X-Git-Url: https://git.saurik.com/apple/xnu.git/blobdiff_plain/fa4905b191e0d16b0fffd53bd565eca71d01fae0..cb3231590a3c94ab4375e2228bd5e86b0cf1ad7e:/bsd/netinet/tcp_input.c diff --git a/bsd/netinet/tcp_input.c b/bsd/netinet/tcp_input.c index 92f3697c2..d7d04516a 100644 --- a/bsd/netinet/tcp_input.c +++ b/bsd/netinet/tcp_input.c @@ -1,23 +1,29 @@ /* - * Copyright (c) 2000 Apple Computer, Inc. All rights reserved. + * Copyright (c) 2000-2019 Apple Inc. All rights reserved. * - * @APPLE_LICENSE_HEADER_START@ - * - * The contents of this file constitute Original Code as defined in and - * are subject to the Apple Public Source License Version 1.1 (the - * "License"). You may not use this file except in compliance with the - * License. Please obtain a copy of the License at - * http://www.apple.com/publicsource and read it before using this file. - * - * This Original Code and all software distributed under the License are - * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER + * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ + * + * This file contains Original Code and/or Modifications of Original Code + * as defined in and that are subject to the Apple Public Source License + * Version 2.0 (the 'License'). You may not use this file except in + * compliance with the License. The rights granted to you under the License + * may not be used to create, or enable the creation or redistribution of, + * unlawful or unlicensed copies of an Apple operating system, or to + * circumvent, violate, or enable the circumvention or violation of, any + * terms of an Apple operating system software license agreement. + * + * Please obtain a copy of the License at + * http://www.opensource.apple.com/apsl/ and read it before using this file. + * + * The Original Code and all software distributed under the License are + * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, - * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the - * License for the specific language governing rights and limitations - * under the License. - * - * @APPLE_LICENSE_HEADER_END@ + * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. + * Please see the License for the specific language governing rights and + * limitations under the License. + * + * @APPLE_OSREFERENCE_LICENSE_HEADER_END@ */ /* * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995 @@ -52,12 +58,14 @@ * SUCH DAMAGE. * * @(#)tcp_input.c 8.12 (Berkeley) 5/24/95 + * $FreeBSD: src/sys/netinet/tcp_input.c,v 1.107.2.16 2001/08/22 00:59:12 silby Exp $ + */ +/* + * NOTICE: This file was modified by SPARTA, Inc. in 2005 to introduce + * support for mandatory and extensible security protections. This notice + * is included in support of clause 2.2 (b) of the Apple Public License, + * Version 2.0. */ - -#if ISFB31 -#include "opt_ipfw.h" /* for ipfw_fwd */ -#include "opt_tcpdebug.h" -#endif #include #include @@ -65,25 +73,37 @@ #include #include #include -#include /* for proc0 declaration */ +#include /* for proc0 declaration */ #include #include #include #include +#include +#if !CONFIG_EMBEDDED +#include +#endif +#include +#include /* before tcp_seq.h, for tcp_random18() */ -#include /* before tcp_seq.h, for tcp_random18() */ +#include #include +#include #include +#include +#include +#include +#include #include #include #include -#include /* for ICMP_BANDLIM */ +#include /* for ICMP_BANDLIM */ #include -#include -#include /* for ICMP_BANDLIM */ +#include /* for ICMP_BANDLIM */ #include +#include +#include #if INET6 #include #include @@ -92,168 +112,605 @@ #include #endif #include +#include #include #include #include #include +#include +#include +#include +#if INET6 +#include +#endif #include #if TCPDEBUG #include -#if INET6 -union { - struct ip _tcp_si4; - struct ip6_hdr _tcp_si6; -} tcp_saveip; -#else -struct ip tcp_saveip; -#endif /* INET6 */ +u_char tcp_saveipgen[40]; /* the size must be of max ip header, now IPv6 */ struct tcphdr tcp_savetcp; #endif /* TCPDEBUG */ +#include #if IPSEC #include +#if INET6 +#include +#endif #include #endif /*IPSEC*/ +#if CONFIG_MACF_NET || CONFIG_MACF_SOCKET +#include +#endif /* CONFIG_MACF_NET || CONFIG_MACF_SOCKET */ + #include +#include +#if MPTCP +#include +#include +#include +#endif /* MPTCP */ + +#include -#define DBG_LAYER_BEG NETDBG_CODE(DBG_NETTCP, 0) -#define DBG_LAYER_END NETDBG_CODE(DBG_NETTCP, 2) +#define DBG_LAYER_BEG NETDBG_CODE(DBG_NETTCP, 0) +#define DBG_LAYER_END NETDBG_CODE(DBG_NETTCP, 2) #define DBG_FNC_TCP_INPUT NETDBG_CODE(DBG_NETTCP, (3 << 8)) #define DBG_FNC_TCP_NEWCONN NETDBG_CODE(DBG_NETTCP, (7 << 8)) -static int tcprexmtthresh = 3; -tcp_seq tcp_iss; -tcp_cc tcp_ccgen; -extern int apple_hwcksum_rx; +#define TCP_RTT_HISTORY_EXPIRE_TIME (60 * TCP_RETRANSHZ) +#define TCP_RECV_THROTTLE_WIN (5 * TCP_RETRANSHZ) +#define TCP_STRETCHACK_ENABLE_PKTCNT 2000 + +struct tcpstat tcpstat; + +static int log_in_vain = 0; +SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_in_vain, + CTLFLAG_RW | CTLFLAG_LOCKED, &log_in_vain, 0, + "Log all incoming TCP connections"); + +static int blackhole = 0; +SYSCTL_INT(_net_inet_tcp, OID_AUTO, blackhole, + CTLFLAG_RW | CTLFLAG_LOCKED, &blackhole, 0, + "Do not send RST when dropping refused connections"); + +SYSCTL_SKMEM_TCP_INT(OID_AUTO, delayed_ack, + CTLFLAG_RW | CTLFLAG_LOCKED, int, tcp_delack_enabled, 3, + "Delay ACK to try and piggyback it onto a data packet"); + +SYSCTL_SKMEM_TCP_INT(OID_AUTO, tcp_lq_overflow, + CTLFLAG_RW | CTLFLAG_LOCKED, int, tcp_lq_overflow, 1, + "Listen Queue Overflow"); + +SYSCTL_SKMEM_TCP_INT(OID_AUTO, recvbg, CTLFLAG_RW | CTLFLAG_LOCKED, + int, tcp_recv_bg, 0, "Receive background"); + +#if TCP_DROP_SYNFIN +SYSCTL_SKMEM_TCP_INT(OID_AUTO, drop_synfin, + CTLFLAG_RW | CTLFLAG_LOCKED, static int, drop_synfin, 1, + "Drop TCP packets with SYN+FIN set"); +#endif + +SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass, CTLFLAG_RW | CTLFLAG_LOCKED, 0, + "TCP Segment Reassembly Queue"); + +static int tcp_reass_overflows = 0; +SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, overflows, + CTLFLAG_RD | CTLFLAG_LOCKED, &tcp_reass_overflows, 0, + "Global number of TCP Segment Reassembly Queue Overflows"); + + +SYSCTL_SKMEM_TCP_INT(OID_AUTO, slowlink_wsize, CTLFLAG_RW | CTLFLAG_LOCKED, + __private_extern__ int, slowlink_wsize, 8192, + "Maximum advertised window size for slowlink"); -struct tcpstat tcpstat; -SYSCTL_STRUCT(_net_inet_tcp, TCPCTL_STATS, stats, - CTLFLAG_RD, &tcpstat , tcpstat, ""); +SYSCTL_SKMEM_TCP_INT(OID_AUTO, maxseg_unacked, + CTLFLAG_RW | CTLFLAG_LOCKED, int, maxseg_unacked, 8, + "Maximum number of outstanding segments left unacked"); -int log_in_vain = 0; -SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_in_vain, CTLFLAG_RW, - &log_in_vain, 0, ""); +SYSCTL_SKMEM_TCP_INT(OID_AUTO, rfc3465, CTLFLAG_RW | CTLFLAG_LOCKED, + int, tcp_do_rfc3465, 1, ""); -int tcp_delack_enabled = 1; -SYSCTL_INT(_net_inet_tcp, OID_AUTO, delayed_ack, CTLFLAG_RW, - &tcp_delack_enabled, 0, ""); +SYSCTL_SKMEM_TCP_INT(OID_AUTO, rfc3465_lim2, + CTLFLAG_RW | CTLFLAG_LOCKED, int, tcp_do_rfc3465_lim2, 1, + "Appropriate bytes counting w/ L=2*SMSS"); + +int rtt_samples_per_slot = 20; + +int tcp_acc_iaj_high_thresh = ACC_IAJ_HIGH_THRESH; +u_int32_t tcp_autorcvbuf_inc_shift = 3; +SYSCTL_SKMEM_TCP_INT(OID_AUTO, recv_allowed_iaj, + CTLFLAG_RW | CTLFLAG_LOCKED, int, tcp_allowed_iaj, ALLOWED_IAJ, + "Allowed inter-packet arrival jiter"); +#if (DEVELOPMENT || DEBUG) +SYSCTL_INT(_net_inet_tcp, OID_AUTO, acc_iaj_high_thresh, + CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_acc_iaj_high_thresh, 0, + "Used in calculating maximum accumulated IAJ"); + +SYSCTL_INT(_net_inet_tcp, OID_AUTO, autorcvbufincshift, + CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_autorcvbuf_inc_shift, 0, + "Shift for increment in receive socket buffer size"); +#endif /* (DEVELOPMENT || DEBUG) */ + +SYSCTL_SKMEM_TCP_INT(OID_AUTO, doautorcvbuf, + CTLFLAG_RW | CTLFLAG_LOCKED, u_int32_t, tcp_do_autorcvbuf, 1, + "Enable automatic socket buffer tuning"); + +SYSCTL_SKMEM_TCP_INT(OID_AUTO, autorcvbufmax, + CTLFLAG_RW | CTLFLAG_LOCKED, u_int32_t, tcp_autorcvbuf_max, 512 * 1024, + "Maximum receive socket buffer size"); + +#if CONFIG_EMBEDDED +int sw_lro = 1; +#else +int sw_lro = 0; +#endif /* !CONFIG_EMBEDDED */ +SYSCTL_INT(_net_inet_tcp, OID_AUTO, lro, CTLFLAG_RW | CTLFLAG_LOCKED, + &sw_lro, 0, "Used to coalesce TCP packets"); + +int lrodebug = 0; +SYSCTL_INT(_net_inet_tcp, OID_AUTO, lrodbg, + CTLFLAG_RW | CTLFLAG_LOCKED, &lrodebug, 0, + "Used to debug SW LRO"); + +int lro_start = 4; +SYSCTL_INT(_net_inet_tcp, OID_AUTO, lro_startcnt, + CTLFLAG_RW | CTLFLAG_LOCKED, &lro_start, 0, + "Segments for starting LRO computed as power of 2"); + +int limited_txmt = 1; +int early_rexmt = 1; +int sack_ackadv = 1; +int tcp_dsack_enable = 1; + +#if (DEVELOPMENT || DEBUG) +SYSCTL_INT(_net_inet_tcp, OID_AUTO, limited_transmit, + CTLFLAG_RW | CTLFLAG_LOCKED, &limited_txmt, 0, + "Enable limited transmit"); + +SYSCTL_INT(_net_inet_tcp, OID_AUTO, early_rexmt, + CTLFLAG_RW | CTLFLAG_LOCKED, &early_rexmt, 0, + "Enable Early Retransmit"); + +SYSCTL_INT(_net_inet_tcp, OID_AUTO, sack_ackadv, + CTLFLAG_RW | CTLFLAG_LOCKED, &sack_ackadv, 0, + "Use SACK with cumulative ack advancement as a dupack"); + +SYSCTL_INT(_net_inet_tcp, OID_AUTO, dsack_enable, + CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_dsack_enable, 0, + "use DSACK TCP option to report duplicate segments"); + +#endif /* (DEVELOPMENT || DEBUG) */ +int tcp_disable_access_to_stats = 1; +SYSCTL_INT(_net_inet_tcp, OID_AUTO, disable_access_to_stats, + CTLFLAG_RW | CTLFLAG_LOCKED, &tcp_disable_access_to_stats, 0, + "Disable access to tcpstat"); + +SYSCTL_SKMEM_TCP_INT(OID_AUTO, challengeack_limit, + CTLFLAG_RW | CTLFLAG_LOCKED, uint32_t, tcp_challengeack_limit, 10, + "Maximum number of challenge ACKs per connection per second"); + +SYSCTL_SKMEM_TCP_INT(OID_AUTO, do_rfc5961, + CTLFLAG_RW | CTLFLAG_LOCKED, static int, tcp_do_rfc5961, 1, + "Enable/Disable full RFC 5961 compliance"); + +extern int tcp_acc_iaj_high; +extern int tcp_acc_iaj_react_limit; + +int tcprexmtthresh = 3; + +u_int32_t tcp_now; +struct timeval tcp_uptime; /* uptime when tcp_now was last updated */ +lck_spin_t *tcp_uptime_lock; /* Used to sychronize updates to tcp_now */ -u_long tcp_now; struct inpcbhead tcb; -#define tcb6 tcb /* for KAME src sync over BSD*'s */ +#define tcb6 tcb /* for KAME src sync over BSD*'s */ struct inpcbinfo tcbinfo; -static void tcp_dooptions __P((struct tcpcb *, - u_char *, int, struct tcphdr *, struct tcpopt *)); -static void tcp_pulloutofband __P((struct socket *, - struct tcphdr *, struct mbuf *)); -static void tcp_xmit_timer __P((struct tcpcb *, int)); +static void tcp_dooptions(struct tcpcb *, u_char *, int, struct tcphdr *, + struct tcpopt *); +static void tcp_finalize_options(struct tcpcb *, struct tcpopt *, unsigned int); +static void tcp_pulloutofband(struct socket *, + struct tcphdr *, struct mbuf *, int); +static void tcp_xmit_timer(struct tcpcb *, int, u_int32_t, tcp_seq); +static inline unsigned int tcp_maxmtu(struct rtentry *); +static inline int tcp_stretch_ack_enable(struct tcpcb *tp, int thflags); +static inline void tcp_adaptive_rwtimo_check(struct tcpcb *, int); + +#if TRAFFIC_MGT +static inline void update_iaj_state(struct tcpcb *tp, uint32_t tlen, + int reset_size); +void compute_iaj(struct tcpcb *tp, int nlropkts, int lro_delay_factor); +static void compute_iaj_meat(struct tcpcb *tp, uint32_t cur_iaj); +#endif /* TRAFFIC_MGT */ + +#if INET6 +static inline unsigned int tcp_maxmtu6(struct rtentry *); +#endif + +unsigned int get_maxmtu(struct rtentry *); + +static void tcp_sbrcv_grow(struct tcpcb *tp, struct sockbuf *sb, + struct tcpopt *to, u_int32_t tlen, u_int32_t rcvbuf_max); +void tcp_sbrcv_trim(struct tcpcb *tp, struct sockbuf *sb); +static void tcp_sbsnd_trim(struct sockbuf *sbsnd); +static inline void tcp_sbrcv_tstmp_check(struct tcpcb *tp); +static inline void tcp_sbrcv_reserve(struct tcpcb *tp, struct sockbuf *sb, + u_int32_t newsize, u_int32_t idealsize, u_int32_t rcvbuf_max); +static void tcp_bad_rexmt_restore_state(struct tcpcb *tp, struct tcphdr *th); +static void tcp_compute_rtt(struct tcpcb *tp, struct tcpopt *to, + struct tcphdr *th); +static void tcp_early_rexmt_check(struct tcpcb *tp, struct tcphdr *th); +static void tcp_bad_rexmt_check(struct tcpcb *tp, struct tcphdr *th, + struct tcpopt *to); +/* + * Constants used for resizing receive socket buffer + * when timestamps are not supported + */ +#define TCPTV_RCVNOTS_QUANTUM 100 +#define TCP_RCVNOTS_BYTELEVEL 204800 /* - * Neighbor Discovery, Neighbor Unreachability Detection - * Upper layer hint. + * Constants used for limiting early retransmits + * to 10 per minute. */ -#define ND6_HINT(tp) { \ - if ((tp) && (tp)->t_inpcb && (tp)->t_inpcb->in6p_route.ro_rt) \ - nd6_nud_hint((tp)->t_inpcb->in6p_route.ro_rt, NULL); \ +#define TCP_EARLY_REXMT_WIN (60 * TCP_RETRANSHZ) /* 60 seconds */ +#define TCP_EARLY_REXMT_LIMIT 10 + +extern void ipfwsyslog( int level, const char *format, ...); +extern int fw_verbose; + +#if IPFIREWALL +extern void ipfw_stealth_stats_incr_tcp(void); + +#define log_in_vain_log( a ) { \ + if ( (log_in_vain == 3 ) && (fw_verbose == 2)) { /* Apple logging, log to ipfw.log */ \ + ipfwsyslog a ; \ + } else if ( (log_in_vain == 4 ) && (fw_verbose == 2)) { \ + ipfw_stealth_stats_incr_tcp(); \ + } \ + else log a ; \ } +#else +#define log_in_vain_log( a ) { log a; } +#endif +int tcp_rcvunackwin = TCPTV_UNACKWIN; +int tcp_maxrcvidle = TCPTV_MAXRCVIDLE; +SYSCTL_SKMEM_TCP_INT(OID_AUTO, rcvsspktcnt, CTLFLAG_RW | CTLFLAG_LOCKED, + int, tcp_rcvsspktcnt, TCP_RCV_SS_PKTCOUNT, "packets to be seen before receiver stretches acks"); -extern u_long current_active_connections; -extern u_long last_active_conn_count; +#define DELAY_ACK(tp, th) \ + (CC_ALGO(tp)->delay_ack != NULL && CC_ALGO(tp)->delay_ack(tp, th)) -extern u_long *delack_bitmask; +static int tcp_dropdropablreq(struct socket *head); +static void tcp_newreno_partial_ack(struct tcpcb *tp, struct tcphdr *th); +static void update_base_rtt(struct tcpcb *tp, uint32_t rtt); +void tcp_set_background_cc(struct socket *so); +void tcp_set_foreground_cc(struct socket *so); +static void tcp_set_new_cc(struct socket *so, uint16_t cc_index); +static void tcp_bwmeas_check(struct tcpcb *tp); +#if TRAFFIC_MGT +void +reset_acc_iaj(struct tcpcb *tp) +{ + tp->acc_iaj = 0; + CLEAR_IAJ_STATE(tp); +} +static inline void +update_iaj_state(struct tcpcb *tp, uint32_t size, int rst_size) +{ + if (rst_size > 0) { + tp->iaj_size = 0; + } + if (tp->iaj_size == 0 || size >= tp->iaj_size) { + tp->iaj_size = size; + tp->iaj_rcv_ts = tcp_now; + tp->iaj_small_pkt = 0; + } +} +/* For every 32 bit unsigned integer(v), this function will find the + * largest integer n such that (n*n <= v). This takes at most 16 iterations + * irrespective of the value of v and does not involve multiplications. + */ +static inline int +isqrt(unsigned int val) +{ + unsigned int sqrt_cache[11] = {0, 1, 4, 9, 16, 25, 36, 49, 64, 81, 100}; + unsigned int temp, g = 0, b = 0x8000, bshft = 15; + if (val <= 100) { + for (g = 0; g <= 10; ++g) { + if (sqrt_cache[g] > val) { + g--; + break; + } else if (sqrt_cache[g] == val) { + break; + } + } + } else { + do { + temp = (((g << 1) + b) << (bshft--)); + if (val >= temp) { + g += b; + val -= temp; + } + b >>= 1; + } while (b > 0 && val > 0); + } + return g; +} /* - * Insert segment ti into reassembly queue of tcp with - * control block tp. Return TH_FIN if reassembly now includes - * a segment with FIN. The macro form does the common case inline - * (segment is the next to be received on an established connection, - * and the queue is empty), avoiding linkage into and removal - * from the queue and repetition of various conversions. - * Set DELACK for segments received in order, but ack immediately - * when segments are out of order (so fast retransmit can work). + * With LRO, roughly estimate the inter arrival time between + * each sub coalesced packet as an average. Count the delay + * cur_iaj to be the delay between the last packet received + * and the first packet of the LRO stream. Due to round off errors + * cur_iaj may be the same as lro_delay_factor. Averaging has + * round off errors too. lro_delay_factor may be close to 0 + * in steady state leading to lower values fed to compute_iaj_meat. */ -#if INET6 -#define _ONLY_IF_INET6_(x) x -#else -#define _ONLY_IF_INET6_(x) -#endif -#define TCP_REASS(tp, th, tilen, m, so, flags, isipv6, needwakeup) { \ - if ((th)->th_seq == (tp)->rcv_nxt && \ - (tp)->segq.lh_first == NULL && \ - (tp)->t_state == TCPS_ESTABLISHED) { \ - if (tcp_delack_enabled) {\ - if (last_active_conn_count > DELACK_BITMASK_THRESH) \ - TCP_DELACK_BITSET(tp->t_inpcb->hash_element); \ - tp->t_flags |= TF_DELACK; \ - } \ - else \ - tp->t_flags |= TF_ACKNOW; \ - (tp)->rcv_nxt += (tilen); \ - flags = (th)->th_flags & TH_FIN; \ - tcpstat.tcps_rcvpack++;\ - tcpstat.tcps_rcvbyte += (tilen);\ - _ONLY_IF_INET6_(ND6_HINT(tp);) \ - sbappend(&(so)->so_rcv, (m)); \ - needwakeup++; \ - } else { \ - (flags) = tcp_reass((tp), (th), (tilen), (m), (isipv6)); \ - tp->t_flags |= TF_ACKNOW; \ - } \ +void +compute_iaj(struct tcpcb *tp, int nlropkts, int lro_delay_factor) +{ + uint32_t cur_iaj = tcp_now - tp->iaj_rcv_ts; + uint32_t timediff = 0; + + if (cur_iaj >= lro_delay_factor) { + cur_iaj = cur_iaj - lro_delay_factor; + } + + compute_iaj_meat(tp, cur_iaj); + + if (nlropkts <= 1) { + return; + } + + nlropkts--; + + timediff = lro_delay_factor / nlropkts; + + while (nlropkts > 0) { + compute_iaj_meat(tp, timediff); + nlropkts--; + } +} + +static +void +compute_iaj_meat(struct tcpcb *tp, uint32_t cur_iaj) +{ + /* When accumulated IAJ reaches MAX_ACC_IAJ in milliseconds, + * throttle the receive window to a minimum of MIN_IAJ_WIN packets + */ +#define MAX_ACC_IAJ (tcp_acc_iaj_high_thresh + tcp_acc_iaj_react_limit) +#define IAJ_DIV_SHIFT 4 +#define IAJ_ROUNDUP_CONST (1 << (IAJ_DIV_SHIFT - 1)) + + uint32_t allowed_iaj, acc_iaj = 0; + + uint32_t mean, temp; + int32_t cur_iaj_dev; + + cur_iaj_dev = (cur_iaj - tp->avg_iaj); + + /* Allow a jitter of "allowed_iaj" milliseconds. Some connections + * may have a constant jitter more than that. We detect this by + * using standard deviation. + */ + allowed_iaj = tp->avg_iaj + tp->std_dev_iaj; + if (allowed_iaj < tcp_allowed_iaj) { + allowed_iaj = tcp_allowed_iaj; + } + + /* Initially when the connection starts, the senders congestion + * window is small. During this period we avoid throttling a + * connection because we do not have a good starting point for + * allowed_iaj. IAJ_IGNORE_PKTCNT is used to quietly gloss over + * the first few packets. + */ + if (tp->iaj_pktcnt > IAJ_IGNORE_PKTCNT) { + if (cur_iaj <= allowed_iaj) { + if (tp->acc_iaj >= 2) { + acc_iaj = tp->acc_iaj - 2; + } else { + acc_iaj = 0; + } + } else { + acc_iaj = tp->acc_iaj + (cur_iaj - allowed_iaj); + } + + if (acc_iaj > MAX_ACC_IAJ) { + acc_iaj = MAX_ACC_IAJ; + } + tp->acc_iaj = acc_iaj; + } + + /* Compute weighted average where the history has a weight of + * 15 out of 16 and the current value has a weight of 1 out of 16. + * This will make the short-term measurements have more weight. + * + * The addition of 8 will help to round-up the value + * instead of round-down + */ + tp->avg_iaj = (((tp->avg_iaj << IAJ_DIV_SHIFT) - tp->avg_iaj) + + cur_iaj + IAJ_ROUNDUP_CONST) >> IAJ_DIV_SHIFT; + + /* Compute Root-mean-square of deviation where mean is a weighted + * average as described above. + */ + temp = tp->std_dev_iaj * tp->std_dev_iaj; + mean = (((temp << IAJ_DIV_SHIFT) - temp) + + (cur_iaj_dev * cur_iaj_dev) + + IAJ_ROUNDUP_CONST) >> IAJ_DIV_SHIFT; + + tp->std_dev_iaj = isqrt(mean); + + DTRACE_TCP3(iaj, struct tcpcb *, tp, uint32_t, cur_iaj, + uint32_t, allowed_iaj); + + return; } +#endif /* TRAFFIC_MGT */ /* - * Note: - * in the ip header part of the ipqe_tcp structure only the length is used. + * Perform rate limit check per connection per second + * tp->t_challengeack_last is the last_time diff was greater than 1sec + * tp->t_challengeack_count is the number of ACKs sent (within 1sec) + * Return TRUE if we shouldn't send the ACK due to rate limitation + * Return FALSE if it is still ok to send challenge ACK */ -int -tcp_reass(tp, th, tilen, m, isipv6) - register struct tcpcb *tp; - register struct tcphdr *th; - u_int16_t tilen; - struct mbuf *m; -#if INET6 - int isipv6; -#endif +static boolean_t +tcp_is_ack_ratelimited(struct tcpcb *tp) { - register struct ipqent *p, *q, *nq, *tiqe; - struct socket *so = tp->t_inpcb->inp_socket; - int flags; + boolean_t ret = TRUE; + uint32_t now = tcp_now; + int32_t diff = 0; + + diff = timer_diff(now, 0, tp->t_challengeack_last, 0); + /* If it is first time or diff > 1000ms, + * update the challengeack_last and reset the + * current count of ACKs + */ + if (tp->t_challengeack_last == 0 || diff >= 1000) { + tp->t_challengeack_last = now; + tp->t_challengeack_count = 0; + ret = FALSE; + } else if (tp->t_challengeack_count < tcp_challengeack_limit) { + ret = FALSE; + } + + /* Careful about wrap-around */ + if (ret == FALSE && (tp->t_challengeack_count + 1 > 0)) { + tp->t_challengeack_count++; + } + + return ret; +} + +/* Check if enough amount of data has been acknowledged since + * bw measurement was started + */ +static void +tcp_bwmeas_check(struct tcpcb *tp) +{ + int32_t bw_meas_bytes; + uint32_t bw, bytes, elapsed_time; + + if (SEQ_LEQ(tp->snd_una, tp->t_bwmeas->bw_start)) { + return; + } + + bw_meas_bytes = tp->snd_una - tp->t_bwmeas->bw_start; + if ((tp->t_flagsext & TF_BWMEAS_INPROGRESS) && + bw_meas_bytes >= (int32_t)(tp->t_bwmeas->bw_size)) { + bytes = bw_meas_bytes; + elapsed_time = tcp_now - tp->t_bwmeas->bw_ts; + if (elapsed_time > 0) { + bw = bytes / elapsed_time; + if (bw > 0) { + if (tp->t_bwmeas->bw_sndbw > 0) { + tp->t_bwmeas->bw_sndbw = + (((tp->t_bwmeas->bw_sndbw << 3) + - tp->t_bwmeas->bw_sndbw) + + bw) >> 3; + } else { + tp->t_bwmeas->bw_sndbw = bw; + } + + /* Store the maximum value */ + if (tp->t_bwmeas->bw_sndbw_max == 0) { + tp->t_bwmeas->bw_sndbw_max = + tp->t_bwmeas->bw_sndbw; + } else { + tp->t_bwmeas->bw_sndbw_max = + max(tp->t_bwmeas->bw_sndbw, + tp->t_bwmeas->bw_sndbw_max); + } + } + } + tp->t_flagsext &= ~(TF_BWMEAS_INPROGRESS); + } +} + +static int +tcp_reass(struct tcpcb *tp, struct tcphdr *th, int *tlenp, struct mbuf *m, + struct ifnet *ifp, int *dowakeup) +{ + struct tseg_qent *q; + struct tseg_qent *p = NULL; + struct tseg_qent *nq; + struct tseg_qent *te = NULL; + struct inpcb *inp = tp->t_inpcb; + struct socket *so = inp->inp_socket; + int flags = 0; + struct mbuf *oodata = NULL; + int copy_oodata = 0; + u_int16_t qlimit; + boolean_t cell = IFNET_IS_CELLULAR(ifp); + boolean_t wifi = (!cell && IFNET_IS_WIFI(ifp)); + boolean_t wired = (!wifi && IFNET_IS_WIRED(ifp)); + boolean_t dsack_set = FALSE; /* * Call with th==0 after become established to * force pre-ESTABLISHED data up to user socket. */ - if (th == 0) + if (th == NULL) { goto present; + } -#if 0 /* Not using GETTCP(m) macro */ - m->m_pkthdr.header = ti; -#endif + /* + * If the reassembly queue already has entries or if we are going + * to add a new one, then the connection has reached a loss state. + * Reset the stretch-ack algorithm at this point. + */ + tcp_reset_stretch_ack(tp); + +#if TRAFFIC_MGT + if (tp->acc_iaj > 0) { + reset_acc_iaj(tp); + } +#endif /* TRAFFIC_MGT */ /* - * Allocate a new queue entry, before we throw away any data. - * If we can't, just drop the packet. XXX + * Limit the number of segments in the reassembly queue to prevent + * holding on to too many segments (and thus running out of mbufs). + * Make sure to let the missing segment through which caused this + * queue. Always keep one global queue entry spare to be able to + * process the missing segment. */ - MALLOC(tiqe, struct ipqent *, sizeof (struct ipqent), M_SONAME, M_NOWAIT); - if (tiqe == NULL) { + qlimit = min(max(100, so->so_rcv.sb_hiwat >> 10), + (TCP_AUTORCVBUF_MAX(ifp) >> 10)); + if (th->th_seq != tp->rcv_nxt && + (tp->t_reassqlen + 1) >= qlimit) { + tcp_reass_overflows++; + tcpstat.tcps_rcvmemdrop++; + m_freem(m); + *tlenp = 0; + return 0; + } + + /* Allocate a new queue entry. If we can't, just drop the pkt. XXX */ + te = (struct tseg_qent *) zalloc(tcp_reass_zone); + if (te == NULL) { tcpstat.tcps_rcvmemdrop++; m_freem(m); - return (0); + return 0; } + tp->t_reassqlen++; /* * Find a segment which begins after this one does. */ - for (p = NULL, q = tp->segq.lh_first; q != NULL; - p = q, q = q->ipqe_q.le_next) - if (SEQ_GT(q->ipqe_tcp->ti_seq, th->th_seq)) + LIST_FOREACH(q, &tp->t_segq, tqe_q) { + if (SEQ_GT(q->tqe_th->th_seq, th->th_seq)) { break; + } + p = q; + } /* * If there is a preceding segment, it may provide some of @@ -261,74 +718,133 @@ tcp_reass(tp, th, tilen, m, isipv6) * segment. If it provides all of our data, drop us. */ if (p != NULL) { - register struct tcpiphdr *phdr = p->ipqe_tcp; - register int i; - + int i; /* conversion to int (in i) handles seq wraparound */ - i = phdr->ti_seq + phdr->ti_len - th->th_seq; + i = p->tqe_th->th_seq + p->tqe_len - th->th_seq; if (i > 0) { - if (i >= tilen) { + if (TCP_DSACK_ENABLED(tp) && i > 1) { + /* + * Note duplicate data sequnce numbers + * to report in DSACK option + */ + tp->t_dsack_lseq = th->th_seq; + tp->t_dsack_rseq = th->th_seq + + min(i, *tlenp); + + /* + * Report only the first part of partial/ + * non-contiguous duplicate sequence space + */ + dsack_set = TRUE; + } + if (i >= *tlenp) { tcpstat.tcps_rcvduppack++; - tcpstat.tcps_rcvdupbyte += tilen; + tcpstat.tcps_rcvdupbyte += *tlenp; + if (nstat_collect) { + nstat_route_rx(inp->inp_route.ro_rt, + 1, *tlenp, + NSTAT_RX_FLAG_DUPLICATE); + INP_ADD_STAT(inp, cell, wifi, wired, + rxpackets, 1); + INP_ADD_STAT(inp, cell, wifi, wired, + rxbytes, *tlenp); + tp->t_stat.rxduplicatebytes += *tlenp; + inp_set_activity_bitmap(inp); + } m_freem(m); - FREE(tiqe, M_SONAME); - -#if 1 /* XXX: NetBSD just return 0 here */ + zfree(tcp_reass_zone, te); + te = NULL; + tp->t_reassqlen--; /* * Try to present any queued data * at the left window edge to the user. * This is needed after the 3-WHS * completes. */ - goto present; /* ??? */ -#endif + goto present; } m_adj(m, i); - tilen -= i; + *tlenp -= i; th->th_seq += i; } } + tp->t_rcvoopack++; tcpstat.tcps_rcvoopack++; - tcpstat.tcps_rcvoobyte += tilen; + tcpstat.tcps_rcvoobyte += *tlenp; + if (nstat_collect) { + nstat_route_rx(inp->inp_route.ro_rt, 1, *tlenp, + NSTAT_RX_FLAG_OUT_OF_ORDER); + INP_ADD_STAT(inp, cell, wifi, wired, rxpackets, 1); + INP_ADD_STAT(inp, cell, wifi, wired, rxbytes, *tlenp); + tp->t_stat.rxoutoforderbytes += *tlenp; + inp_set_activity_bitmap(inp); + } /* * While we overlap succeeding segments trim them or, * if they are completely covered, dequeue them. */ while (q) { - register struct tcpiphdr *qhdr = q->ipqe_tcp; - register int i = (th->th_seq + tilen) - qhdr->ti_seq; - - if (i <= 0) + int i = (th->th_seq + *tlenp) - q->tqe_th->th_seq; + if (i <= 0) { break; - if (i < qhdr->ti_len) { - qhdr->ti_seq += i; - qhdr->ti_len -= i; - m_adj(q->ipqe_m, i); + } + + /* + * Report only the first part of partial/non-contiguous + * duplicate segment in dsack option. The variable + * dsack_set will be true if a previous entry has some of + * the duplicate sequence space. + */ + if (TCP_DSACK_ENABLED(tp) && i > 1 && !dsack_set) { + if (tp->t_dsack_lseq == 0) { + tp->t_dsack_lseq = q->tqe_th->th_seq; + tp->t_dsack_rseq = + tp->t_dsack_lseq + min(i, q->tqe_len); + } else { + /* + * this segment overlaps data in multple + * entries in the reassembly queue, move + * the right sequence number further. + */ + tp->t_dsack_rseq = + tp->t_dsack_rseq + min(i, q->tqe_len); + } + } + if (i < q->tqe_len) { + q->tqe_th->th_seq += i; + q->tqe_len -= i; + m_adj(q->tqe_m, i); break; } - nq = q->ipqe_q.le_next; - m_freem(q->ipqe_m); - LIST_REMOVE(q, ipqe_q); - FREE(q, M_SONAME); + + nq = LIST_NEXT(q, tqe_q); + LIST_REMOVE(q, tqe_q); + m_freem(q->tqe_m); + zfree(tcp_reass_zone, q); + tp->t_reassqlen--; q = nq; } - /* Insert the new fragment queue entry into place. */ - tiqe->ipqe_m = m; - /* - * There is a IP or IPv6 header in the mbuf before th - * so there is space for an ip header (for the length field) - */ -#define thtoti(x) \ - ((struct tcpiphdr *)(((char *)(x)) - (sizeof (struct ip)))) + /* Insert the new segment queue entry into place. */ + te->tqe_m = m; + te->tqe_th = th; + te->tqe_len = *tlenp; - tiqe->ipqe_tcp = thtoti(th); - tiqe->ipqe_tcp->ti_len = tilen; if (p == NULL) { - LIST_INSERT_HEAD(&tp->segq, tiqe, ipqe_q); + LIST_INSERT_HEAD(&tp->t_segq, te, tqe_q); } else { - LIST_INSERT_AFTER(p, tiqe, ipqe_q); + LIST_INSERT_AFTER(p, te, tqe_q); + } + + /* + * New out-of-order data exists, and is pointed to by + * queue entry te. Set copy_oodata to 1 so out-of-order data + * can be copied off to sockbuf after in-order data + * is copied off. + */ + if (!(so->so_state & SS_CANTRCVMORE)) { + copy_oodata = 1; } present: @@ -336,42 +852,197 @@ present: * Present data to user, advancing rcv_nxt through * completed sequence space. */ - if (!TCPS_HAVEESTABLISHED(tp->t_state)) - return (0); - q = tp->segq.lh_first; - if (!q || q->ipqe_tcp->ti_seq != tp->rcv_nxt) - return (0); -#if 0 - /* - * XXX from INRIA for NetBSD, but should not happen because - * TCPS_HAVEESTABLISHED(tp->t_state) should be true here. - */ - if (tp->t_state == TCPS_SYN_RECEIVED && q->ipqe_tcp->ti_len) - return (0); -#endif + if (!TCPS_HAVEESTABLISHED(tp->t_state)) { + return 0; + } + q = LIST_FIRST(&tp->t_segq); + if (!q || q->tqe_th->th_seq != tp->rcv_nxt) { + /* Stop using LRO once out of order packets arrive */ + if (tp->t_flagsext & TF_LRO_OFFLOADED) { + tcp_lro_remove_state(inp->inp_laddr, inp->inp_faddr, + th->th_dport, th->th_sport); + tp->t_flagsext &= ~TF_LRO_OFFLOADED; + } + + /* + * continue processing if out-of-order data + * can be delivered + */ + if (q && (so->so_flags & SOF_ENABLE_MSGS)) { + goto msg_unordered_delivery; + } + + return 0; + } + + /* + * If there is already another thread doing reassembly for this + * connection, it is better to let it finish the job -- + * (radar 16316196) + */ + if (tp->t_flagsext & TF_REASS_INPROG) { + return 0; + } + + tp->t_flagsext |= TF_REASS_INPROG; + /* lost packet was recovered, so ooo data can be returned */ + tcpstat.tcps_recovered_pkts++; + do { - tp->rcv_nxt += q->ipqe_tcp->ti_len; - flags = q->ipqe_tcp->ti_flags & TH_FIN; - nq = q->ipqe_q.le_next; - LIST_REMOVE(q, ipqe_q); - if (so->so_state & SS_CANTRCVMORE) - m_freem(q->ipqe_m); - else - sbappend(&so->so_rcv, q->ipqe_m); - FREE(q, M_SONAME); - q = nq; - } while (q && q->ipqe_tcp->ti_seq == tp->rcv_nxt); + tp->rcv_nxt += q->tqe_len; + flags = q->tqe_th->th_flags & TH_FIN; + LIST_REMOVE(q, tqe_q); + if (so->so_state & SS_CANTRCVMORE) { + m_freem(q->tqe_m); + } else { + /* + * The mbuf may be freed after it has been added to the + * receive socket buffer so we reinitialize th to point + * to a safe copy of the TCP header + */ + struct tcphdr saved_tcphdr = {}; + + so_recv_data_stat(so, q->tqe_m, 0); /* XXXX */ + if (so->so_flags & SOF_ENABLE_MSGS) { + /* + * Append the inorder data as a message to the + * receive socket buffer. Also check to see if + * the data we are about to deliver is the same + * data that we wanted to pass up to the user + * out of order. If so, reset copy_oodata -- + * the received data filled a gap, and + * is now in order! + */ + if (q == te) { + copy_oodata = 0; + } + } + memcpy(&saved_tcphdr, th, sizeof(struct tcphdr)); + if (sbappendstream_rcvdemux(so, q->tqe_m, + q->tqe_th->th_seq - (tp->irs + 1), 0)) { + *dowakeup = 1; + } + th = &saved_tcphdr; + + if (tp->t_flagsext & TF_LRO_OFFLOADED) { + tcp_update_lro_seq(tp->rcv_nxt, + inp->inp_laddr, inp->inp_faddr, + th->th_dport, th->th_sport); + } + } + zfree(tcp_reass_zone, q); + tp->t_reassqlen--; + q = LIST_FIRST(&tp->t_segq); + } while (q && q->tqe_th->th_seq == tp->rcv_nxt); + tp->t_flagsext &= ~TF_REASS_INPROG; + #if INET6 - if (isipv6) - ND6_HINT(tp); + if ((inp->inp_vflag & INP_IPV6) != 0) { + KERNEL_DEBUG(DBG_LAYER_BEG, + ((inp->inp_fport << 16) | inp->inp_lport), + (((inp->in6p_laddr.s6_addr16[0] & 0xffff) << 16) | + (inp->in6p_faddr.s6_addr16[0] & 0xffff)), + 0, 0, 0); + } else #endif + { + KERNEL_DEBUG(DBG_LAYER_BEG, + ((inp->inp_fport << 16) | inp->inp_lport), + (((inp->inp_laddr.s_addr & 0xffff) << 16) | + (inp->inp_faddr.s_addr & 0xffff)), + 0, 0, 0); + } + +msg_unordered_delivery: + /* Deliver out-of-order data as a message */ + if (te && (so->so_flags & SOF_ENABLE_MSGS) && copy_oodata && te->tqe_len) { + /* + * make a copy of the mbuf to be delivered up to + * the user, and add it to the sockbuf + */ + oodata = m_copym(te->tqe_m, 0, M_COPYALL, M_DONTWAIT); + if (oodata != NULL) { + if (sbappendmsgstream_rcv(&so->so_rcv, oodata, + te->tqe_th->th_seq - (tp->irs + 1), 1)) { + *dowakeup = 1; + tcpstat.tcps_msg_unopkts++; + } else { + tcpstat.tcps_msg_unoappendfail++; + } + } + } + + return flags; +} + +/* + * Reduce congestion window -- used when ECN is seen or when a tail loss + * probe recovers the last packet. + */ +static void +tcp_reduce_congestion_window( + struct tcpcb *tp) +{ + /* + * If the current tcp cc module has + * defined a hook for tasks to run + * before entering FR, call it + */ + if (CC_ALGO(tp)->pre_fr != NULL) { + CC_ALGO(tp)->pre_fr(tp); + } + ENTER_FASTRECOVERY(tp); + if (tp->t_flags & TF_SENTFIN) { + tp->snd_recover = tp->snd_max - 1; + } else { + tp->snd_recover = tp->snd_max; + } + tp->t_timer[TCPT_REXMT] = 0; + tp->t_timer[TCPT_PTO] = 0; + tp->t_rtttime = 0; + if (tp->t_flagsext & TF_CWND_NONVALIDATED) { + tcp_cc_adjust_nonvalidated_cwnd(tp); + } else { + tp->snd_cwnd = tp->snd_ssthresh + + tp->t_maxseg * tcprexmtthresh; + } +} - KERNEL_DEBUG(DBG_LAYER_END, ((th->th_dport << 16) | th->th_sport), - (((thtoti(th)->ti_src.s_addr & 0xffff) << 16) | (thtoti(th)->ti_dst.s_addr & 0xffff)), - th->th_seq, th->th_ack, th->th_win); +/* + * This function is called upon reception of data on a socket. It's purpose is + * to handle the adaptive keepalive timers that monitor whether the connection + * is making progress. First the adaptive read-timer, second the TFO probe-timer. + * + * The application wants to get an event if there is a stall during read. + * Set the initial keepalive timeout to be equal to twice RTO. + * + * If the outgoing interface is in marginal conditions, we need to + * enable read probes for that too. + */ +static inline void +tcp_adaptive_rwtimo_check(struct tcpcb *tp, int tlen) +{ + struct ifnet *outifp = tp->t_inpcb->inp_last_outifp; + + if ((tp->t_adaptive_rtimo > 0 || + (outifp != NULL && + (outifp->if_eflags & IFEF_PROBE_CONNECTIVITY))) + && tlen > 0 && + tp->t_state == TCPS_ESTABLISHED) { + tp->t_timer[TCPT_KEEP] = OFFSET_FROM_START(tp, + (TCP_REXMTVAL(tp) << 1)); + tp->t_flagsext |= TF_DETECT_READSTALL; + tp->t_rtimo_probes = 0; + } +} - sorwakeup(so); - return (flags); +inline void +tcp_keepalive_reset(struct tcpcb *tp) +{ + tp->t_timer[TCPT_KEEP] = OFFSET_FROM_START(tp, + TCP_CONN_KEEPIDLE(tp)); + tp->t_flagsext &= ~(TF_DETECT_READSTALL); + tp->t_rtimo_probes = 0; } /* @@ -380,2605 +1051,6119 @@ present: */ #if INET6 int -tcp6_input(mp, offp, proto) - struct mbuf **mp; - int *offp, proto; +tcp6_input(struct mbuf **mp, int *offp, int proto) { - tcp_input(*mp, *offp); +#pragma unused(proto) + struct mbuf *m = *mp; + uint32_t ia6_flags; + struct ifnet *ifp = m->m_pkthdr.rcvif; + + IP6_EXTHDR_CHECK(m, *offp, sizeof(struct tcphdr), return IPPROTO_DONE); + + /* Expect 32-bit aligned data pointer on strict-align platforms */ + MBUF_STRICT_DATA_ALIGNMENT_CHECK_32(m); + + /* + * draft-itojun-ipv6-tcp-to-anycast + * better place to put this in? + */ + if (ip6_getdstifaddr_info(m, NULL, &ia6_flags) == 0) { + if (ia6_flags & IN6_IFF_ANYCAST) { + struct ip6_hdr *ip6; + + ip6 = mtod(m, struct ip6_hdr *); + icmp6_error(m, ICMP6_DST_UNREACH, + ICMP6_DST_UNREACH_ADDR, + (caddr_t)&ip6->ip6_dst - (caddr_t)ip6); + + IF_TCP_STATINC(ifp, icmp6unreach); + + return IPPROTO_DONE; + } + } + + tcp_input(m, *offp); return IPPROTO_DONE; } #endif -void -tcp_input(m, off) - struct mbuf *m; - int off; +/* Depending on the usage of mbuf space in the system, this function + * will return true or false. This is used to determine if a socket + * buffer can take more memory from the system for auto-tuning or not. + */ +u_int8_t +tcp_cansbgrow(struct sockbuf *sb) { - register struct tcphdr *th; - register struct ip *ip = NULL; - register struct ipovly *ipov; - register struct inpcb *inp; - u_char *optp = NULL; - int optlen = 0; - int len, toff; - int hdroptlen; - u_int16_t tilen; - register struct tcpcb *tp = 0; - register int thflags; - struct socket *so = 0; - int todrop, acked, ourfinisacked, needoutput = 0; - struct in_addr laddr; -#if 0 - struct in6_addr laddr6; -#endif - int dropsocket = 0; - int iss = 0; - u_long tiwin; - struct tcpopt to; /* options in this segment */ - struct rmxp_tao *taop; /* pointer to our TAO cache entry */ - struct rmxp_tao tao_noncached; /* in case there's no cached entry */ - int need_sowwakeup = 0; - int need_sorwakeup = 0; -#if TCPDEBUG - short ostate = 0; -#endif -#if INET6 - struct ip6_hdr *ip6 = NULL; - int lgminh; -#else /* INET6 */ -#define lgminh (sizeof (struct tcpiphdr)) -#endif /* INET6 */ - int isipv6 = (mtod(m, struct ip *)->ip_v == 6) ? 1 : 0; + /* Calculate the host level space limit in terms of MSIZE buffers. + * We can use a maximum of half of the available mbuf space for + * socket buffers. + */ + u_int32_t mblim = ((nmbclusters >> 1) << (MCLSHIFT - MSIZESHIFT)); - struct proc *proc0=current_proc(); + /* Calculate per sb limit in terms of bytes. We optimize this limit + * for upto 16 socket buffers. + */ - KERNEL_DEBUG(DBG_FNC_TCP_INPUT | DBG_FUNC_START,0,0,0,0,0); + u_int32_t sbspacelim = ((nmbclusters >> 4) << MCLSHIFT); - bzero((char *)&to, sizeof(to)); + if ((total_sbmb_cnt < mblim) && + (sb->sb_hiwat < sbspacelim)) { + return 1; + } else { + OSIncrementAtomic64(&sbmb_limreached); + } + return 0; +} - tcpstat.tcps_rcvtotal++; - /* - * Get IP and TCP header together in first mbuf. - * Note: IP leaves IP header in first mbuf. +static void +tcp_sbrcv_reserve(struct tcpcb *tp, struct sockbuf *sbrcv, + u_int32_t newsize, u_int32_t idealsize, u_int32_t rcvbuf_max) +{ + /* newsize should not exceed max */ + newsize = min(newsize, rcvbuf_max); + + /* The receive window scale negotiated at the + * beginning of the connection will also set a + * limit on the socket buffer size */ - th = mtod(m, struct tcpiphdr *); + newsize = min(newsize, TCP_MAXWIN << tp->rcv_scale); - KERNEL_DEBUG(DBG_LAYER_BEG, ((th->th_dport << 16) | th->th_sport), - (((thtoti(th)->ti_src.s_addr & 0xffff) << 16) | (thtoti(th)->ti_dst.s_addr & 0xffff)), - th->th_seq, th->th_ack, th->th_win); + /* Set new socket buffer size */ + if (newsize > sbrcv->sb_hiwat && + (sbreserve(sbrcv, newsize) == 1)) { + sbrcv->sb_idealsize = min(max(sbrcv->sb_idealsize, + (idealsize != 0) ? idealsize : newsize), rcvbuf_max); -#if INET6 - if (isipv6) { - ip6 = mtod(m, struct ip6_hdr *); - lgminh = sizeof(struct tcpip6hdr); - } else { - lgminh = sizeof(struct tcpiphdr); -#endif /* INET6 */ - ip = mtod(m, struct ip *); - ipov = (struct ipovly *)ip; -#if INET6 + /* Again check the limit set by the advertised + * window scale + */ + sbrcv->sb_idealsize = min(sbrcv->sb_idealsize, + TCP_MAXWIN << tp->rcv_scale); } -#endif /* INET6 */ +} -#if INET6 - /* XXX not a good place to put this into... */ - if (isipv6 && - m && (m->m_flags & M_ANYCAST6)) { - icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR, - (caddr_t)&ip6->ip6_dst - (caddr_t)ip6); - return; +/* + * This function is used to grow a receive socket buffer. It + * will take into account system-level memory usage and the + * bandwidth available on the link to make a decision. + */ +static void +tcp_sbrcv_grow(struct tcpcb *tp, struct sockbuf *sbrcv, + struct tcpopt *to, u_int32_t pktlen, u_int32_t rcvbuf_max) +{ + struct socket *so = sbrcv->sb_so; + + /* + * Do not grow the receive socket buffer if + * - auto resizing is disabled, globally or on this socket + * - the high water mark already reached the maximum + * - the stream is in background and receive side is being + * throttled + * - if there are segments in reassembly queue indicating loss, + * do not need to increase recv window during recovery as more + * data is not going to be sent. A duplicate ack sent during + * recovery should not change the receive window + */ + if (tcp_do_autorcvbuf == 0 || + (sbrcv->sb_flags & SB_AUTOSIZE) == 0 || + tcp_cansbgrow(sbrcv) == 0 || + sbrcv->sb_hiwat >= rcvbuf_max || + (tp->t_flagsext & TF_RECV_THROTTLE) || + (so->so_flags1 & SOF1_EXTEND_BK_IDLE_WANTED) || + !LIST_EMPTY(&tp->t_segq)) { + /* Can not resize the socket buffer, just return */ + goto out; } -#endif /* INET6 */ -#if INET6 - if (isipv6) { - IP6_EXTHDR_CHECK(m, off, sizeof(struct tcphdr), ); - ip6 = mtod(m, struct ip6_hdr *); - tilen = ntohs(ip6->ip6_plen) - off + sizeof(*ip6); + if (TSTMP_GT(tcp_now, + tp->rfbuf_ts + TCPTV_RCVBUFIDLE)) { + /* If there has been an idle period in the + * connection, just restart the measurement + */ + goto out; + } - if (in6_cksum(m, IPPROTO_TCP, off, tilen)) { - tcpstat.tcps_rcvbadsum++; - goto drop; - } - th = (struct tcphdr *)((caddr_t)ip6 + off); - } else -#endif /* INET6 */ - { + if (!TSTMP_SUPPORTED(tp)) { /* - * Get IP and TCP header together in first mbuf. - * Note: IP leaves IP header in first mbuf. + * Timestamp option is not supported on this connection. + * If the connection reached a state to indicate that + * the receive socket buffer needs to grow, increase + * the high water mark. */ - /* XXX: should we still require this for IPv4? */ - if (off > sizeof (struct ip)) { - ip_stripoptions(m, (struct mbuf *)0); - off = sizeof(struct ip); - if (m->m_pkthdr.csum_flags & CSUM_TCP_SUM16) - m->m_pkthdr.csum_flags = 0; /* invalidate hwcksuming */ + if (TSTMP_GEQ(tcp_now, + tp->rfbuf_ts + TCPTV_RCVNOTS_QUANTUM)) { + if (tp->rfbuf_cnt + pktlen >= TCP_RCVNOTS_BYTELEVEL) { + tcp_sbrcv_reserve(tp, sbrcv, + tcp_autorcvbuf_max, 0, + tcp_autorcvbuf_max); + } + goto out; + } else { + tp->rfbuf_cnt += pktlen; + return; } - if (m->m_len < lgminh) { - if ((m = m_pullup(m, lgminh)) == 0) { - tcpstat.tcps_rcvshort++; - return; + } else if (to->to_tsecr != 0) { + /* + * If the timestamp shows that one RTT has + * completed, we can stop counting the + * bytes. Here we consider increasing + * the socket buffer if the bandwidth measured in + * last rtt, is more than half of sb_hiwat, this will + * help to scale the buffer according to the bandwidth + * on the link. + */ + if (TSTMP_GEQ(to->to_tsecr, tp->rfbuf_ts)) { + if (tp->rfbuf_cnt + pktlen > (sbrcv->sb_hiwat - + (sbrcv->sb_hiwat >> 1))) { + tp->rfbuf_cnt += pktlen; + int32_t rcvbuf_inc, min_incr; + /* + * Increment the receive window by a + * multiple of maximum sized segments. + * This will prevent a connection from + * sending smaller segments on wire if it + * is limited by the receive window. + * + * Set the ideal size based on current + * bandwidth measurements. We set the + * ideal size on receive socket buffer to + * be twice the bandwidth delay product. + */ + rcvbuf_inc = (tp->rfbuf_cnt << 1) + - sbrcv->sb_hiwat; + + /* + * Make the increment equal to 8 segments + * at least + */ + min_incr = tp->t_maxseg << tcp_autorcvbuf_inc_shift; + if (rcvbuf_inc < min_incr) { + rcvbuf_inc = min_incr; + } + + rcvbuf_inc = + (rcvbuf_inc / tp->t_maxseg) * tp->t_maxseg; + tcp_sbrcv_reserve(tp, sbrcv, + sbrcv->sb_hiwat + rcvbuf_inc, + (tp->rfbuf_cnt << 1), rcvbuf_max); } + /* Measure instantaneous receive bandwidth */ + if (tp->t_bwmeas != NULL && tp->rfbuf_cnt > 0 && + TSTMP_GT(tcp_now, tp->rfbuf_ts)) { + u_int32_t rcv_bw; + rcv_bw = tp->rfbuf_cnt / + (int)(tcp_now - tp->rfbuf_ts); + if (tp->t_bwmeas->bw_rcvbw_max == 0) { + tp->t_bwmeas->bw_rcvbw_max = rcv_bw; + } else { + tp->t_bwmeas->bw_rcvbw_max = max( + tp->t_bwmeas->bw_rcvbw_max, rcv_bw); + } + } + goto out; + } else { + tp->rfbuf_cnt += pktlen; + return; } - ip = mtod(m, struct ip *); - ipov = (struct ipovly *)ip; - th = (struct tcphdr *)((caddr_t)ip + off); - tilen = ip->ip_len; - len = sizeof (struct ip) + tilen; - - if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) { - - if (apple_hwcksum_rx && (m->m_pkthdr.csum_flags & CSUM_TCP_SUM16)) { - u_short pseudo; - bzero(ipov->ih_x1, sizeof(ipov->ih_x1)); - ipov->ih_len = (u_short)tilen; - HTONS(ipov->ih_len); - pseudo = in_cksum(m, sizeof (struct ip)); - th->th_sum = in_addword(pseudo, (m->m_pkthdr.csum_data & 0xFFFF)); - } - else { - if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) - th->th_sum = m->m_pkthdr.csum_data; - else goto dotcpcksum; - } - th->th_sum ^= 0xffff; - - } else { - /* - * Checksum extended TCP header and data. - */ -dotcpcksum: - if (th->th_sum) { - len = sizeof (struct ip) + tilen; - bzero(ipov->ih_x1, sizeof(ipov->ih_x1)); - ipov->ih_len = (u_short)tilen; - HTONS(ipov->ih_len); - th = (struct tcphdr *)((caddr_t)ip + off); - th->th_sum = in_cksum(m, len); - } - } - - if (th->th_sum) { - tcpstat.tcps_rcvbadsum++; - goto drop; + } +out: + /* Restart the measurement */ + tp->rfbuf_ts = 0; + tp->rfbuf_cnt = 0; + return; +} + +/* This function will trim the excess space added to the socket buffer + * to help a slow-reading app. The ideal-size of a socket buffer depends + * on the link bandwidth or it is set by an application and we aim to + * reach that size. + */ +void +tcp_sbrcv_trim(struct tcpcb *tp, struct sockbuf *sbrcv) +{ + if (tcp_do_autorcvbuf == 1 && sbrcv->sb_idealsize > 0 && + sbrcv->sb_hiwat > sbrcv->sb_idealsize) { + int32_t trim; + /* compute the difference between ideal and current sizes */ + u_int32_t diff = sbrcv->sb_hiwat - sbrcv->sb_idealsize; + + /* Compute the maximum advertised window for + * this connection. + */ + u_int32_t advwin = tp->rcv_adv - tp->rcv_nxt; + + /* How much can we trim the receive socket buffer? + * 1. it can not be trimmed beyond the max rcv win advertised + * 2. if possible, leave 1/16 of bandwidth*delay to + * avoid closing the win completely + */ + u_int32_t leave = max(advwin, (sbrcv->sb_idealsize >> 4)); + + /* Sometimes leave can be zero, in that case leave at least + * a few segments worth of space. + */ + if (leave == 0) { + leave = tp->t_maxseg << tcp_autorcvbuf_inc_shift; + } + + trim = sbrcv->sb_hiwat - (sbrcv->sb_cc + leave); + trim = imin(trim, (int32_t)diff); + + if (trim > 0) { + sbreserve(sbrcv, (sbrcv->sb_hiwat - trim)); + } + } +} + +/* We may need to trim the send socket buffer size for two reasons: + * 1. if the rtt seen on the connection is climbing up, we do not + * want to fill the buffers any more. + * 2. if the congestion win on the socket backed off, there is no need + * to hold more mbufs for that connection than what the cwnd will allow. + */ +void +tcp_sbsnd_trim(struct sockbuf *sbsnd) +{ + if (tcp_do_autosendbuf == 1 && + ((sbsnd->sb_flags & (SB_AUTOSIZE | SB_TRIM)) == + (SB_AUTOSIZE | SB_TRIM)) && + (sbsnd->sb_idealsize > 0) && + (sbsnd->sb_hiwat > sbsnd->sb_idealsize)) { + u_int32_t trim = 0; + if (sbsnd->sb_cc <= sbsnd->sb_idealsize) { + trim = sbsnd->sb_hiwat - sbsnd->sb_idealsize; + } else { + trim = sbsnd->sb_hiwat - sbsnd->sb_cc; } + sbreserve(sbsnd, (sbsnd->sb_hiwat - trim)); + } + if (sbsnd->sb_hiwat <= sbsnd->sb_idealsize) { + sbsnd->sb_flags &= ~(SB_TRIM); + } +} + +/* + * If timestamp option was not negotiated on this connection + * and this connection is on the receiving side of a stream + * then we can not measure the delay on the link accurately. + * Instead of enabling automatic receive socket buffer + * resizing, just give more space to the receive socket buffer. + */ +static inline void +tcp_sbrcv_tstmp_check(struct tcpcb *tp) +{ + struct socket *so = tp->t_inpcb->inp_socket; + u_int32_t newsize = 2 * tcp_recvspace; + struct sockbuf *sbrcv = &so->so_rcv; + + if ((tp->t_flags & (TF_REQ_TSTMP | TF_RCVD_TSTMP)) != + (TF_REQ_TSTMP | TF_RCVD_TSTMP) && + (sbrcv->sb_flags & SB_AUTOSIZE) != 0) { + tcp_sbrcv_reserve(tp, sbrcv, newsize, 0, newsize); + } +} + +/* A receiver will evaluate the flow of packets on a connection + * to see if it can reduce ack traffic. The receiver will start + * stretching acks if all of the following conditions are met: + * 1. tcp_delack_enabled is set to 3 + * 2. If the bytes received in the last 100ms is greater than a threshold + * defined by maxseg_unacked + * 3. If the connection has not been idle for tcp_maxrcvidle period. + * 4. If the connection has seen enough packets to let the slow-start + * finish after connection establishment or after some packet loss. + * + * The receiver will stop stretching acks if there is congestion/reordering + * as indicated by packets on reassembly queue or an ECN. If the delayed-ack + * timer fires while stretching acks, it means that the packet flow has gone + * below the threshold defined by maxseg_unacked and the receiver will stop + * stretching acks. The receiver gets no indication when slow-start is completed + * or when the connection reaches an idle state. That is why we use + * tcp_rcvsspktcnt to cover slow-start and tcp_maxrcvidle to identify idle + * state. + */ +static inline int +tcp_stretch_ack_enable(struct tcpcb *tp, int thflags) +{ + if (tp->rcv_by_unackwin >= (maxseg_unacked * tp->t_maxseg) && + TSTMP_GEQ(tp->rcv_unackwin, tcp_now)) { + tp->t_flags |= TF_STREAMING_ON; + } else { + tp->t_flags &= ~TF_STREAMING_ON; + } + + /* If there has been an idle time, reset streaming detection */ + if (TSTMP_GT(tcp_now, tp->rcv_unackwin + tcp_maxrcvidle)) { + tp->t_flags &= ~TF_STREAMING_ON; } /* - * Check that TCP offset makes sense, - * pull out TCP options and adjust length. XXX + * If there are flags other than TH_ACK set, reset streaming + * detection */ - toff = th->th_off << 2; - if (toff < sizeof (struct tcphdr) || toff > tilen) { - tcpstat.tcps_rcvbadoff++; - goto drop; + if (thflags & ~TH_ACK) { + tp->t_flags &= ~TF_STREAMING_ON; } - tilen -= toff; - if (toff > sizeof (struct tcphdr)) { -#if INET6 - if (isipv6) { - IP6_EXTHDR_CHECK(m, off, toff, ); - ip6 = mtod(m, struct ip6_hdr *); - th = (struct tcphdr *)((caddr_t)ip6 + off); - } else -#endif /* INET6 */ - { - if (m->m_len < sizeof(struct ip) + toff) { - if ((m = m_pullup(m, sizeof (struct ip) + toff)) == 0) { - tcpstat.tcps_rcvshort++; - return; - } - ip = mtod(m, struct ip *); - ipov = (struct ipovly *)ip; - th = (struct tcphdr *)((caddr_t)ip + off); + + if (tp->t_flagsext & TF_DISABLE_STRETCHACK) { + if (tp->rcv_nostrack_pkts >= TCP_STRETCHACK_ENABLE_PKTCNT) { + tp->t_flagsext &= ~TF_DISABLE_STRETCHACK; + tp->rcv_nostrack_pkts = 0; + tp->rcv_nostrack_ts = 0; + } else { + tp->rcv_nostrack_pkts++; + } + } + + if (!(tp->t_flagsext & (TF_NOSTRETCHACK | TF_DISABLE_STRETCHACK)) && + (tp->t_flags & TF_STREAMING_ON) && + (!(tp->t_flagsext & TF_RCVUNACK_WAITSS) || + (tp->rcv_waitforss >= tcp_rcvsspktcnt))) { + return 1; + } + + return 0; +} + +/* + * Reset the state related to stretch-ack algorithm. This will make + * the receiver generate an ack every other packet. The receiver + * will start re-evaluating the rate at which packets come to decide + * if it can benefit by lowering the ack traffic. + */ +void +tcp_reset_stretch_ack(struct tcpcb *tp) +{ + tp->t_flags &= ~(TF_STRETCHACK | TF_STREAMING_ON); + tp->rcv_by_unackwin = 0; + tp->rcv_by_unackhalfwin = 0; + tp->rcv_unackwin = tcp_now + tcp_rcvunackwin; + + /* + * When there is packet loss or packet re-ordering or CWR due to + * ECN, the sender's congestion window is reduced. In these states, + * generate an ack for every other packet for some time to allow + * the sender's congestion window to grow. + */ + tp->t_flagsext |= TF_RCVUNACK_WAITSS; + tp->rcv_waitforss = 0; +} + +/* + * The last packet was a retransmission, check if this ack + * indicates that the retransmission was spurious. + * + * If the connection supports timestamps, we could use it to + * detect if the last retransmit was not needed. Otherwise, + * we check if the ACK arrived within RTT/2 window, then it + * was a mistake to do the retransmit in the first place. + * + * This function will return 1 if it is a spurious retransmit, + * 0 otherwise. + */ +int +tcp_detect_bad_rexmt(struct tcpcb *tp, struct tcphdr *th, + struct tcpopt *to, u_int32_t rxtime) +{ + int32_t tdiff, bad_rexmt_win; + bad_rexmt_win = (tp->t_srtt >> (TCP_RTT_SHIFT + 1)); + + /* If the ack has ECN CE bit, then cwnd has to be adjusted */ + if (TCP_ECN_ENABLED(tp) && (th->th_flags & TH_ECE)) { + return 0; + } + if (TSTMP_SUPPORTED(tp)) { + if (rxtime > 0 && (to->to_flags & TOF_TS) + && to->to_tsecr != 0 + && TSTMP_LT(to->to_tsecr, rxtime)) { + return 1; + } + } else { + if ((tp->t_rxtshift == 1 + || (tp->t_flagsext & TF_SENT_TLPROBE)) + && rxtime > 0) { + tdiff = (int32_t)(tcp_now - rxtime); + if (tdiff < bad_rexmt_win) { + return 1; } } - optlen = toff - sizeof (struct tcphdr); - optp = (u_char *)(th + 1); - /* - * Do quick retrieval of timestamp options ("options - * prediction?"). If timestamp is the only option and it's - * formatted as recommended in RFC 1323 appendix A, we - * quickly get the values now and not bother calling - * tcp_dooptions(), etc. + } + return 0; +} + + +/* + * Restore congestion window state if a spurious timeout + * was detected. + */ +static void +tcp_bad_rexmt_restore_state(struct tcpcb *tp, struct tcphdr *th) +{ + if (TSTMP_SUPPORTED(tp)) { + u_int32_t fsize, acked; + fsize = tp->snd_max - th->th_ack; + acked = BYTES_ACKED(th, tp); + + /* + * Implement bad retransmit recovery as + * described in RFC 4015. */ - if ((optlen == TCPOLEN_TSTAMP_APPA || - (optlen > TCPOLEN_TSTAMP_APPA && - optp[TCPOLEN_TSTAMP_APPA] == TCPOPT_EOL)) && - *(u_int32_t *)optp == htonl(TCPOPT_TSTAMP_HDR) && - (th->th_flags & TH_SYN) == 0) { - to.to_flag |= TOF_TS; - to.to_tsval = ntohl(*(u_int32_t *)(optp + 4)); - to.to_tsecr = ntohl(*(u_int32_t *)(optp + 8)); - optp = NULL; /* we've parsed the options */ + tp->snd_ssthresh = tp->snd_ssthresh_prev; + + /* Initialize cwnd to the initial window */ + if (CC_ALGO(tp)->cwnd_init != NULL) { + CC_ALGO(tp)->cwnd_init(tp); + } + + tp->snd_cwnd = fsize + min(acked, tp->snd_cwnd); + } else { + tp->snd_cwnd = tp->snd_cwnd_prev; + tp->snd_ssthresh = tp->snd_ssthresh_prev; + if (tp->t_flags & TF_WASFRECOVERY) { + ENTER_FASTRECOVERY(tp); } + + /* Do not use the loss flight size in this case */ + tp->t_lossflightsize = 0; } - thflags = th->th_flags; + tp->snd_cwnd = max(tp->snd_cwnd, TCP_CC_CWND_INIT_BYTES); + tp->snd_recover = tp->snd_recover_prev; + tp->snd_nxt = tp->snd_max; - /* - * Convert TCP protocol specific fields to host format. - */ - NTOHL(th->th_seq); - NTOHL(th->th_ack); - NTOHS(th->th_win); - NTOHS(th->th_urp); + /* Fix send socket buffer to reflect the change in cwnd */ + tcp_bad_rexmt_fix_sndbuf(tp); /* - * Drop TCP, IP headers and TCP options. + * This RTT might reflect the extra delay induced + * by the network. Skip using this sample for RTO + * calculation and mark the connection so we can + * recompute RTT when the next eligible sample is + * found. */ - hdroptlen = off+toff; - m->m_data += hdroptlen; - m->m_len -= hdroptlen; + tp->t_flagsext |= TF_RECOMPUTE_RTT; + tp->t_badrexmt_time = tcp_now; + tp->t_rtttime = 0; +} - /* - * Locate pcb for segment. - */ -findpcb: -#if IPFIREWALL_FORWARD - if (ip_fw_fwd_addr != NULL -#if INET6 - && isipv6 == NULL -#endif /* INET6 */ - ) { +/* + * If the previous packet was sent in retransmission timer, and it was + * not needed, then restore the congestion window to the state before that + * transmission. + * + * If the last packet was sent in tail loss probe timeout, check if that + * recovered the last packet. If so, that will indicate a real loss and + * the congestion window needs to be lowered. + */ +static void +tcp_bad_rexmt_check(struct tcpcb *tp, struct tcphdr *th, struct tcpopt *to) +{ + if (tp->t_rxtshift > 0 && + tcp_detect_bad_rexmt(tp, th, to, tp->t_rxtstart)) { + ++tcpstat.tcps_sndrexmitbad; + tcp_bad_rexmt_restore_state(tp, th); + tcp_ccdbg_trace(tp, th, TCP_CC_BAD_REXMT_RECOVERY); + } else if ((tp->t_flagsext & TF_SENT_TLPROBE) + && tp->t_tlphighrxt > 0 + && SEQ_GEQ(th->th_ack, tp->t_tlphighrxt) + && !tcp_detect_bad_rexmt(tp, th, to, tp->t_tlpstart)) { /* - * Diverted. Pretend to be the destination. - * already got one like this? + * check DSACK information also to make sure that + * the TLP was indeed needed */ - inp = in_pcblookup_hash(&tcbinfo, ip->ip_src, th->th_sport, - ip->ip_dst, th->th_dport, 0, m->m_pkthdr.rcvif); - if (!inp) { - /* - * No, then it's new. Try find the ambushing socket + if (tcp_rxtseg_dsack_for_tlp(tp)) { + /* + * received a DSACK to indicate that TLP was + * not needed */ - if (!ip_fw_fwd_addr->sin_port) { - inp = in_pcblookup_hash(&tcbinfo, ip->ip_src, - th->th_sport, ip_fw_fwd_addr->sin_addr, - th->th_dport, 1, m->m_pkthdr.rcvif); - } else { - inp = in_pcblookup_hash(&tcbinfo, - ip->ip_src, th->th_sport, - ip_fw_fwd_addr->sin_addr, - ntohs(ip_fw_fwd_addr->sin_port), 1, - m->m_pkthdr.rcvif); - } + tcp_rxtseg_clean(tp); + goto out; } - ip_fw_fwd_addr = NULL; - } else -#endif /* IPFIREWALL_FORWARD */ - -#if INET6 - if (isipv6) - inp = in6_pcblookup_hash(&tcbinfo, &ip6->ip6_src, th->th_sport, - &ip6->ip6_dst, th->th_dport, 1, - m->m_pkthdr.rcvif); - else -#endif /* INET6 */ - inp = in_pcblookup_hash(&tcbinfo, ip->ip_src, th->th_sport, - ip->ip_dst, th->th_dport, 1, m->m_pkthdr.rcvif); -#if IPSEC - /* due to difference from other BSD stacks */ - m->m_data -= hdroptlen; - m->m_len += hdroptlen; -#if INET6 - if (isipv6) { - if (inp != NULL && ipsec6_in_reject_so(m, inp->inp_socket)) { - ipsec6stat.in_polvio++; - goto drop; + /* + * The tail loss probe recovered the last packet and + * we need to adjust the congestion window to take + * this loss into account. + */ + ++tcpstat.tcps_tlp_recoverlastpkt; + if (!IN_FASTRECOVERY(tp)) { + tcp_reduce_congestion_window(tp); + EXIT_FASTRECOVERY(tp); } - } else -#endif /* INET6 */ - if (inp != NULL && ipsec4_in_reject_so(m, inp->inp_socket)) { - ipsecstat.in_polvio++; - goto drop; + tcp_ccdbg_trace(tp, th, TCP_CC_TLP_RECOVER_LASTPACKET); + } else if (tcp_rxtseg_detect_bad_rexmt(tp, th->th_ack)) { + /* + * All of the retransmitted segments were duplicated, this + * can be an indication of bad fast retransmit. + */ + tcpstat.tcps_dsack_badrexmt++; + tcp_bad_rexmt_restore_state(tp, th); + tcp_ccdbg_trace(tp, th, TCP_CC_DSACK_BAD_REXMT); + tcp_rxtseg_clean(tp); } - m->m_data += hdroptlen; - m->m_len -= hdroptlen; -#endif /*IPSEC*/ +out: + tp->t_flagsext &= ~(TF_SENT_TLPROBE); + tp->t_tlphighrxt = 0; + tp->t_tlpstart = 0; /* - * If the state is CLOSED (i.e., TCB does not exist) then - * all data in the incoming segment is discarded. - * If the TCB exists but is in CLOSED state, it is embryonic, - * but should either do a listen or a connect soon. + * check if the latest ack was for a segment sent during PMTU + * blackhole detection. If the timestamp on the ack is before + * PMTU blackhole detection, then revert the size of the max + * segment to previous size. */ - if (inp == NULL) { - if (log_in_vain && thflags & TH_SYN) { -#if INET6 - char buf[INET6_ADDRSTRLEN]; -#else /* INET6 */ - char buf[4*sizeof "123"]; -#endif /* INET6 */ - -#if INET6 - if (isipv6) { - strcpy(buf, ip6_sprintf(&ip6->ip6_dst)); - log(LOG_INFO, - "Connection attempt to TCP %s:%d from %s:%d\n", - buf, ntohs(th->th_dport), - ip6_sprintf(&ip6->ip6_src), - ntohs(th->th_sport)); - } else { -#endif - strcpy(buf, inet_ntoa(ip->ip_dst)); - log(LOG_INFO, - "Connection attempt to TCP %s:%d from %s:%d\n", - buf, ntohs(th->th_dport), inet_ntoa(ip->ip_src), - ntohs(th->th_sport)); -#if INET6 - } -#endif /* INET6 */ + if (tp->t_rxtshift > 0 && (tp->t_flags & TF_BLACKHOLE) && + tp->t_pmtud_start_ts > 0 && TSTMP_SUPPORTED(tp)) { + if ((to->to_flags & TOF_TS) && to->to_tsecr != 0 + && TSTMP_LT(to->to_tsecr, tp->t_pmtud_start_ts)) { + tcp_pmtud_revert_segment_size(tp); } -#if ICMP_BANDLIM - if (badport_bandlim(1) < 0) - goto drop; -#endif - goto dropwithreset; } - tp = intotcpcb(inp); - if (tp == 0) - goto dropwithreset; - if (tp->t_state == TCPS_CLOSED) - goto drop; - /* - * Bogus state when listening port owned by SharedIP with loopback as the - * only configured interface: BlueBox does not filters loopback - */ - if (tp->t_state == TCP_NSTATES) - goto drop; + if (tp->t_pmtud_start_ts > 0) { + tp->t_pmtud_start_ts = 0; + } +} - /* Unscale the window into a 32-bit value. */ - if ((thflags & TH_SYN) == 0) - tiwin = th->th_win << tp->snd_scale; - else - tiwin = th->th_win; - - so = inp->inp_socket; - if (so->so_options & (SO_DEBUG|SO_ACCEPTCONN)) { -#if TCPDEBUG - if (so->so_options & SO_DEBUG) { - ostate = tp->t_state; -#if INET6 - if (isipv6) - tcp_saveip._tcp_si6 = *ip6; - else - tcp_saveip._tcp_si4 = *ip; -#else /* INET6 */ - tcp_saveip = *ip; -#endif /* INET6 */ +/* + * Check if early retransmit can be attempted according to RFC 5827. + * + * If packet reordering is detected on a connection, fast recovery will + * be delayed until it is clear that the packet was lost and not reordered. + * But reordering detection is done only when SACK is enabled. + * + * On connections that do not support SACK, there is a limit on the number + * of early retransmits that can be done per minute. This limit is needed + * to make sure that too many packets are not retransmitted when there is + * packet reordering. + */ +static void +tcp_early_rexmt_check(struct tcpcb *tp, struct tcphdr *th) +{ + u_int32_t obytes, snd_off; + int32_t snd_len; + struct socket *so = tp->t_inpcb->inp_socket; - tcp_savetcp = *th; + if (early_rexmt && (SACK_ENABLED(tp) || + tp->t_early_rexmt_count < TCP_EARLY_REXMT_LIMIT) && + SEQ_GT(tp->snd_max, tp->snd_una) && + (tp->t_dupacks == 1 || + (SACK_ENABLED(tp) && + !TAILQ_EMPTY(&tp->snd_holes)))) { + /* + * If there are only a few outstanding + * segments on the connection, we might need + * to lower the retransmit threshold. This + * will allow us to do Early Retransmit as + * described in RFC 5827. + */ + if (SACK_ENABLED(tp) && + !TAILQ_EMPTY(&tp->snd_holes)) { + obytes = (tp->snd_max - tp->snd_fack) + + tp->sackhint.sack_bytes_rexmit; + } else { + obytes = (tp->snd_max - tp->snd_una); } -#endif - if (so->so_options & SO_ACCEPTCONN) { - register struct tcpcb *tp0 = tp; - struct socket *so2; -#if IPSEC - struct socket *oso; -#endif -#if INET6 - struct inpcb *oinp = sotoinpcb(so); -#endif /* INET6 */ -#if !IPSEC - if ((thflags & (TH_RST|TH_ACK|TH_SYN)) != TH_SYN) { - /* - * Note: dropwithreset makes sure we don't - * send a RST in response to a RST. - */ - if (thflags & TH_ACK) { - tcpstat.tcps_badsyn++; - goto dropwithreset; - } - goto drop; + /* + * In order to lower retransmit threshold the + * following two conditions must be met. + * 1. the amount of outstanding data is less + * than 4*SMSS bytes + * 2. there is no unsent data ready for + * transmission or the advertised window + * will limit sending new segments. + */ + snd_off = tp->snd_max - tp->snd_una; + snd_len = min(so->so_snd.sb_cc, tp->snd_wnd) - snd_off; + if (obytes < (tp->t_maxseg << 2) && + snd_len <= 0) { + u_int32_t osegs; + + osegs = obytes / tp->t_maxseg; + if ((osegs * tp->t_maxseg) < obytes) { + osegs++; } -#endif - KERNEL_DEBUG(DBG_FNC_TCP_NEWCONN | DBG_FUNC_START,0,0,0,0,0); - so2 = sonewconn(so, 0); - - if (so2 == 0) { - tcpstat.tcps_listendrop++; - so2 = sodropablereq(so); - if (so2) { - tcp_drop(sototcpcb(so2), ETIMEDOUT); - so2 = sonewconn(so, 0); - } - if (!so2) - goto drop; - } -#if IPSEC - oso = so; -#endif - so = so2; /* - * This is ugly, but .... + * Since the connection might have already + * received some dupacks, we add them to + * to the outstanding segments count to get + * the correct retransmit threshold. * - * Mark socket as temporary until we're - * committed to keeping it. The code at - * ``drop'' and ``dropwithreset'' check the - * flag dropsocket to see if the temporary - * socket created here should be discarded. - * We mark the socket as discardable until - * we're committed to it below in TCPS_LISTEN. + * By checking for early retransmit after + * receiving some duplicate acks when SACK + * is supported, the connection will + * enter fast recovery even if multiple + * segments are lost in the same window. */ - dropsocket++; - inp = (struct inpcb *)so->so_pcb; -#if INET6 - if (isipv6) - inp->in6p_laddr = ip6->ip6_dst; - else { - if (ip6_mapped_addr_on) { - inp->inp_vflag &= ~INP_IPV6; - inp->inp_vflag |= INP_IPV4; + osegs += tp->t_dupacks; + if (osegs < 4) { + tp->t_rexmtthresh = + ((osegs - 1) > 1) ? (osegs - 1) : 1; + tp->t_rexmtthresh = + min(tp->t_rexmtthresh, tcprexmtthresh); + tp->t_rexmtthresh = + max(tp->t_rexmtthresh, tp->t_dupacks); + + if (tp->t_early_rexmt_count == 0) { + tp->t_early_rexmt_win = tcp_now; } -#endif /* INET6 */ - inp->inp_laddr = ip->ip_dst; -#if INET6 - } -#endif /* INET6 */ - inp->inp_lport = th->th_dport; - if (in_pcbinshash(inp) != 0) { - /* - * Undo the assignments above if we failed to put - * the PCB on the hash lists. - */ -#if INET6 - if (isipv6) - inp->in6p_laddr = in6addr_any; - else -#endif /* INET6 */ - inp->inp_laddr.s_addr = INADDR_ANY; - inp->inp_lport = 0; - goto drop; - } -#if IPSEC - /* - * from IPsec perspective, it is important to do it - * after making actual listening socket. - * otherwise, cached security association will bark. - * - * Subject: (KAME-snap 748) - * From: Wayne Knowles - */ - if ((thflags & (TH_RST|TH_ACK|TH_SYN)) != TH_SYN) { - /* - * Note: dropwithreset makes sure we don't - * send a RST in response to a RST. - */ - if (thflags & TH_ACK) { - tcpstat.tcps_badsyn++; - goto dropwithreset; + if (tp->t_flagsext & TF_SENT_TLPROBE) { + tcpstat.tcps_tlp_recovery++; + tcp_ccdbg_trace(tp, th, + TCP_CC_TLP_RECOVERY); + } else { + tcpstat.tcps_early_rexmt++; + tp->t_early_rexmt_count++; + tcp_ccdbg_trace(tp, th, + TCP_CC_EARLY_RETRANSMIT); } - goto drop; } -#endif -#if INET6 - if (isipv6) { - struct ip6_recvpktopts newopts; + } + } - /* - * Inherit socket options from the listening - * socket. - * Note that in6p_inputopts are not (even - * should not be) copied, since it stores - * previously received options and is used to - * detect if each new option is different than - * the previous one and hence should be passed - * to a user. - * If we copied in6p_inputopts, a user would - * not be able to receive options just after - * calling the accept system call. - */ - inp->inp_flags |= - oinp->inp_flags & INP_CONTROLOPTS; - if (oinp->in6p_outputopts) - inp->in6p_outputopts = - ip6_copypktopts(oinp->in6p_outputopts, - M_NOWAIT); - } else -#endif /* INET6 */ - inp->inp_options = ip_srcroute(); -#if IPSEC - /* copy old policy into new socket's */ - if (ipsec_copy_policy(sotoinpcb(oso)->inp_sp, - inp->inp_sp)) - printf("tcp_input: could not copy policy\n"); -#endif + /* + * If we ever sent a TLP probe, the acknowledgement will trigger + * early retransmit because the value of snd_fack will be close + * to snd_max. This will take care of adjustments to the + * congestion window. So we can reset TF_SENT_PROBE flag. + */ + tp->t_flagsext &= ~(TF_SENT_TLPROBE); + tp->t_tlphighrxt = 0; + tp->t_tlpstart = 0; +} - tp = intotcpcb(inp); - tp->t_state = TCPS_LISTEN; - tp->t_flags |= tp0->t_flags & (TF_NOPUSH|TF_NOOPT); +static boolean_t +tcp_tfo_syn(struct tcpcb *tp, struct tcpopt *to) +{ + u_char out[CCAES_BLOCK_SIZE]; + unsigned char len; - /* Compute proper scaling value from buffer space */ - while (tp->request_r_scale < TCP_MAX_WINSHIFT && - TCP_MAXWIN << tp->request_r_scale < so->so_rcv.sb_hiwat) - tp->request_r_scale++; + if (!(to->to_flags & (TOF_TFO | TOF_TFOREQ)) || + !(tcp_fastopen & TCP_FASTOPEN_SERVER)) { + return FALSE; + } - KERNEL_DEBUG(DBG_FNC_TCP_NEWCONN | DBG_FUNC_END,0,0,0,0,0); - } + if ((to->to_flags & TOF_TFOREQ)) { + tp->t_tfo_flags |= TFO_F_OFFER_COOKIE; + + tp->t_tfo_stats |= TFO_S_COOKIEREQ_RECV; + tcpstat.tcps_tfo_cookie_req_rcv++; + return FALSE; } -#if INET6 - /* save packet options if user wanted */ - if (isipv6 && (inp->in6p_flags & INP_CONTROLOPTS) != 0) { - struct ip6_recvpktopts opts6; + /* Ok, then it must be an offered cookie. We need to check that ... */ + tcp_tfo_gen_cookie(tp->t_inpcb, out, sizeof(out)); - /* - * Temporarily re-adjusting the mbuf before ip6_savecontrol(), - * which is necessary for FreeBSD only due to difference from - * other BSD stacks. - * XXX: we'll soon make a more natural fix after getting a - * consensus. - */ -#ifndef DEFER_MADJ - m->m_data -= hdroptlen; - m->m_len += hdroptlen; -#endif - ip6_savecontrol(inp, ip6, m, &opts6, &inp->in6p_inputopts); - if (inp->in6p_inputopts) - ip6_update_recvpcbopt(inp->in6p_inputopts, &opts6); - if (opts6.head) { - if (sbappendcontrol(&inp->in6p_socket->so_rcv, - NULL, opts6.head) - == 0) - m_freem(opts6.head); - } -#ifndef DEFER_MADJ - m->m_data += hdroptlen; /* XXX */ - m->m_len -= hdroptlen; /* XXX */ -#endif + len = *to->to_tfo - TCPOLEN_FASTOPEN_REQ; + to->to_tfo++; + if (memcmp(out, to->to_tfo, len)) { + /* Cookies are different! Let's return and offer a new cookie */ + tp->t_tfo_flags |= TFO_F_OFFER_COOKIE; + + tp->t_tfo_stats |= TFO_S_COOKIE_INVALID; + tcpstat.tcps_tfo_cookie_invalid++; + return FALSE; } -#endif /* INET6 */ - /* - * Segment received on connection. - * Reset idle time and keep-alive timer. - */ - tp->t_idle = 0; - if (TCPS_HAVEESTABLISHED(tp->t_state)) - tp->t_timer[TCPT_KEEP] = tcp_keepidle; + if (OSIncrementAtomic(&tcp_tfo_halfcnt) >= tcp_tfo_backlog) { + /* Need to decrement again as we just increased it... */ + OSDecrementAtomic(&tcp_tfo_halfcnt); + return FALSE; + } - /* - * Process options if not in LISTEN state, - * else do it below (after getting remote address). - */ - if (tp->t_state != TCPS_LISTEN && optp) - tcp_dooptions(tp, optp, optlen, th, &to); - if (th->th_flags & TH_SYN) - tcp_mss(tp, to.to_maxseg, isipv6); /* sets t_maxseg */ + tp->t_tfo_flags |= TFO_F_COOKIE_VALID; - /* - * Header prediction: check for the two common cases - * of a uni-directional data xfer. If the packet has - * no control flags, is in-sequence, the window didn't - * change and we're not retransmitting, it's a - * candidate. If the length is zero and the ack moved - * forward, we're the sender side of the xfer. Just - * free the data acked & wake any higher level process - * that was blocked waiting for space. If the length - * is non-zero and the ack didn't move, we're the - * receiver side. If we're getting packets in-order - * (the reassembly queue is empty), add the data to - * the socket buffer and note that we need a delayed ack. - * Make sure that the hidden state-flags are also off. - * Since we check for TCPS_ESTABLISHED above, it can only - * be TH_NEEDSYN. - */ - if (tp->t_state == TCPS_ESTABLISHED && - (thflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK && - ((tp->t_flags & (TF_NEEDSYN|TF_NEEDFIN)) == 0) && - ((to.to_flag & TOF_TS) == 0 || - TSTMP_GEQ(to.to_tsval, tp->ts_recent)) && - /* - * Using the CC option is compulsory if once started: - * the segment is OK if no T/TCP was negotiated or - * if the segment has a CC option equal to CCrecv - */ - ((tp->t_flags & (TF_REQ_CC|TF_RCVD_CC)) != (TF_REQ_CC|TF_RCVD_CC) || - ((to.to_flag & TOF_CC) != 0 && to.to_cc == tp->cc_recv)) && - th->th_seq == tp->rcv_nxt && - tiwin && tiwin == tp->snd_wnd && - tp->snd_nxt == tp->snd_max) { + tp->t_tfo_stats |= TFO_S_SYNDATA_RCV; + tcpstat.tcps_tfo_syn_data_rcv++; + + return TRUE; +} + +static void +tcp_tfo_synack(struct tcpcb *tp, struct tcpopt *to) +{ + if (to->to_flags & TOF_TFO) { + unsigned char len = *to->to_tfo - TCPOLEN_FASTOPEN_REQ; /* - * If last ACK falls within this segment's sequence numbers, - * record the timestamp. - * NOTE that the test is modified according to the latest - * proposal of the tcplw@cray.com list (Braden 1993/04/26). + * If this happens, things have gone terribly wrong. len should + * have been checked in tcp_dooptions. */ - if ((to.to_flag & TOF_TS) != 0 && - SEQ_LEQ(th->th_seq, tp->last_ack_sent)) { - tp->ts_recent_age = tcp_now; - tp->ts_recent = to.to_tsval; - } + VERIFY(len <= TFO_COOKIE_LEN_MAX); - if (tilen == 0) { - if (SEQ_GT(th->th_ack, tp->snd_una) && - SEQ_LEQ(th->th_ack, tp->snd_max) && - tp->snd_cwnd >= tp->snd_wnd && - tp->t_dupacks < tcprexmtthresh) { - /* - * this is a pure ack for outstanding data. - */ - ++tcpstat.tcps_predack; - if ((to.to_flag & TOF_TS) != 0) - tcp_xmit_timer(tp, - tcp_now - to.to_tsecr + 1); - else if (tp->t_rtt && - SEQ_GT(th->th_ack, tp->t_rtseq)) - tcp_xmit_timer(tp, tp->t_rtt); - acked = th->th_ack - tp->snd_una; - tcpstat.tcps_rcvackpack++; - tcpstat.tcps_rcvackbyte += acked; - sbdrop(&so->so_snd, acked); - tp->snd_una = th->th_ack; - m_freem(m); -#if INET6 - /* some progress has been done */ - if (isipv6) - ND6_HINT(tp); -#endif + to->to_tfo++; - /* - * If all outstanding data are acked, stop - * retransmit timer, otherwise restart timer - * using current (possibly backed-off) value. - * If process is waiting for space, - * wakeup/selwakeup/signal. If data - * are ready to send, let tcp_output - * decide between more output or persist. - */ - if (tp->snd_una == tp->snd_max) - tp->t_timer[TCPT_REXMT] = 0; - else if (tp->t_timer[TCPT_PERSIST] == 0) - tp->t_timer[TCPT_REXMT] = tp->t_rxtcur; + tcp_cache_set_cookie(tp, to->to_tfo, len); + tcp_heuristic_tfo_success(tp); - if (so->so_snd.sb_cc) - (void) tcp_output(tp); - sowwakeup(so); - KERNEL_DEBUG(DBG_FNC_TCP_INPUT | DBG_FUNC_END,0,0,0,0,0); - return; - } - } else if (th->th_ack == tp->snd_una && - tp->segq.lh_first == NULL && - tilen <= sbspace(&so->so_rcv)) { - /* - * this is a pure, in-sequence data packet - * with nothing on the reassembly queue and - * we have enough buffer space to take it. - */ - ++tcpstat.tcps_preddat; - tp->rcv_nxt += tilen; - tcpstat.tcps_rcvpack++; - tcpstat.tcps_rcvbyte += tilen; -#if INET6 - /* some progress has been done */ - if (isipv6) - ND6_HINT(tp); -#endif - sbappend(&so->so_rcv, m); - KERNEL_DEBUG(DBG_LAYER_END, ((th->th_dport << 16) | th->th_sport), - (((thtoti(th)->ti_src.s_addr & 0xffff) << 16) | (thtoti(th)->ti_dst.s_addr & 0xffff)), - th->th_seq, th->th_ack, th->th_win); - if (tcp_delack_enabled) { - if (last_active_conn_count > DELACK_BITMASK_THRESH) - TCP_DELACK_BITSET(tp->t_inpcb->hash_element); - tp->t_flags |= TF_DELACK; - } else { - tp->t_flags |= TF_ACKNOW; - tcp_output(tp); + tp->t_tfo_stats |= TFO_S_COOKIE_RCV; + tcpstat.tcps_tfo_cookie_rcv++; + if (tp->t_tfo_flags & TFO_F_COOKIE_SENT) { + tcpstat.tcps_tfo_cookie_wrong++; + tp->t_tfo_stats |= TFO_S_COOKIE_WRONG; + } + } else { + /* + * Thus, no cookie in the response, but we either asked for one + * or sent SYN+DATA. Now, we need to check whether we had to + * rexmit the SYN. If that's the case, it's better to start + * backing of TFO-cookie requests. + */ + if (!(tp->t_flagsext & TF_FASTOPEN_FORCE_ENABLE) && + tp->t_tfo_flags & TFO_F_SYN_LOSS) { + tp->t_tfo_stats |= TFO_S_SYN_LOSS; + tcpstat.tcps_tfo_syn_loss++; + + tcp_heuristic_tfo_loss(tp); + } else { + if (tp->t_tfo_flags & TFO_F_COOKIE_REQ) { + tp->t_tfo_stats |= TFO_S_NO_COOKIE_RCV; + tcpstat.tcps_tfo_no_cookie_rcv++; } - sorwakeup(so); - KERNEL_DEBUG(DBG_FNC_TCP_INPUT | DBG_FUNC_END,0,0,0,0,0); - return; + + tcp_heuristic_tfo_success(tp); } } +} - /* - * Calculate amount of space in receive window, - * and then do TCP input processing. - * Receive window is amount of space in rcv queue, - * but not less than advertised window. - */ - { int win; - - win = sbspace(&so->so_rcv); - if (win < 0) - win = 0; - tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); +static void +tcp_tfo_rcv_probe(struct tcpcb *tp, int tlen) +{ + if (tlen != 0) { + return; } - switch (tp->t_state) { + tp->t_tfo_probe_state = TFO_PROBE_PROBING; /* - * If the state is LISTEN then ignore segment if it contains an RST. - * If the segment contains an ACK then it is bad and send a RST. - * If it does not contain a SYN then it is not interesting; drop it. - * If it is from this socket, drop it, it must be forged. - * Don't bother responding if the destination was a broadcast. - * Otherwise initialize tp->rcv_nxt, and tp->irs, select an initial - * tp->iss, and send a segment: - * - * Also initialize tp->snd_nxt to tp->iss+1 and tp->snd_una to tp->iss. - * Fill in remote peer address fields if not previously specified. - * Enter SYN_RECEIVED state, and process any other fields of this - * segment in this state. + * We send the probe out rather quickly (after one RTO). It does not + * really hurt that much, it's only one additional segment on the wire. */ - case TCPS_LISTEN: { - register struct sockaddr_in *sin; -#if 0 - register struct sockaddr_in6 *sin6; -#endif + tp->t_timer[TCPT_KEEP] = OFFSET_FROM_START(tp, (TCP_REXMTVAL(tp))); +} - if (thflags & TH_RST) - goto drop; - if (thflags & TH_ACK) - goto dropwithreset; - if ((thflags & TH_SYN) == 0) - goto drop; - if (th->th_dport == th->th_sport) { -#if INET6 - if (isipv6) { - if (IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, - &ip6->ip6_src)) - goto drop; - } else -#endif /* INET6 */ - if (ip->ip_dst.s_addr == ip->ip_src.s_addr) - goto drop; +static void +tcp_tfo_rcv_data(struct tcpcb *tp) +{ + /* Transition from PROBING to NONE as data has been received */ + if (tp->t_tfo_probe_state >= TFO_PROBE_PROBING) { + tp->t_tfo_probe_state = TFO_PROBE_NONE; + } +} + +static void +tcp_tfo_rcv_ack(struct tcpcb *tp, struct tcphdr *th) +{ + if (tp->t_tfo_probe_state == TFO_PROBE_PROBING && + tp->t_tfo_probes > 0) { + if (th->th_seq == tp->rcv_nxt) { + /* No hole, so stop probing */ + tp->t_tfo_probe_state = TFO_PROBE_NONE; + } else if (SEQ_GT(th->th_seq, tp->rcv_nxt)) { + /* There is a hole! Wait a bit for data... */ + tp->t_tfo_probe_state = TFO_PROBE_WAIT_DATA; + tp->t_timer[TCPT_KEEP] = OFFSET_FROM_START(tp, + TCP_REXMTVAL(tp)); } + } +} -#if INET6 - if (isipv6) { - if (m->m_flags & (M_BCAST|M_MCAST) || - IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) - goto drop; -#if 1 - /* - * Perhaps this should be a call/macro - * to a function like in6_pcbconnect(), but almost - * all of the checks have been done: we know - * that the association is unique, and the - * local address is always set here. - */ - if (IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_laddr)) - inp->in6p_laddr = ip6->ip6_dst; - inp->in6p_faddr = ip6->ip6_src; - inp->inp_fport = th->th_sport; +/* + * Update snd_wnd information. + */ +static inline bool +tcp_update_window(struct tcpcb *tp, int thflags, struct tcphdr * th, + u_int32_t tiwin, int tlen) +{ + /* Don't look at the window if there is no ACK flag */ + if ((thflags & TH_ACK) && + (SEQ_LT(tp->snd_wl1, th->th_seq) || + (tp->snd_wl1 == th->th_seq && (SEQ_LT(tp->snd_wl2, th->th_ack) || + (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))) { + /* keep track of pure window updates */ + if (tlen == 0 && + tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) { + tcpstat.tcps_rcvwinupd++; + } + tp->snd_wnd = tiwin; + tp->snd_wl1 = th->th_seq; + tp->snd_wl2 = th->th_ack; + if (tp->snd_wnd > tp->max_sndwnd) { + tp->max_sndwnd = tp->snd_wnd; + } - /* TODO: flowinfo initialization */ + if (tp->t_inpcb->inp_socket->so_flags & SOF_MP_SUBFLOW) { + mptcp_update_window_wakeup(tp); + } + return true; + } + return false; +} - in_pcbrehash(inp); -#else - MALLOC(sin6, struct sockaddr_in6 *, sizeof *sin6, - M_SONAME, M_NOWAIT); - if (sin6 == NULL) - goto drop; - bzero(sin6, sizeof(*sin6)); - sin6->sin6_family = AF_INET6; - sin6->sin6_len = sizeof(*sin6); - sin6->sin6_addr = ip6->ip6_src; - sin6->sin6_port = th->th_sport; - laddr6 = inp->in6p_laddr; - if (IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_laddr)) - inp->in6p_laddr = ip6->ip6_dst; - if (in6_pcbconnect(inp, (struct sockaddr *)sin6, - &proc0)) { - inp->in6p_laddr = laddr6; - FREE(sin6, M_SONAME); - goto drop; - } - FREE(sin6, M_SONAME); +static void +tcp_handle_wakeup(struct socket *so, int read_wakeup, int write_wakeup) +{ + if (read_wakeup != 0) { + sorwakeup(so); + } + if (write_wakeup != 0) { + sowwakeup(so); + } +} + +void +tcp_input(struct mbuf *m, int off0) +{ + struct tcphdr *th; + struct ip *ip = NULL; + struct inpcb *inp; + u_char *optp = NULL; + int optlen = 0; + int tlen, off; + int drop_hdrlen; + struct tcpcb *tp = 0; + int thflags; + struct socket *so = 0; + int todrop, acked, ourfinisacked, needoutput = 0; + int read_wakeup = 0; + int write_wakeup = 0; + struct in_addr laddr; +#if INET6 + struct in6_addr laddr6; #endif - } - else { -#endif /* INET6 */ - /* - * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN - * in_broadcast() should never return true on a received - * packet with M_BCAST not set. - */ - if (m->m_flags & (M_BCAST|M_MCAST) || - IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) - goto drop; - MALLOC(sin, struct sockaddr_in *, sizeof *sin, M_SONAME, - M_NOWAIT); - if (sin == NULL) - goto drop; - sin->sin_family = AF_INET; - sin->sin_len = sizeof(*sin); - sin->sin_addr = ip->ip_src; - sin->sin_port = th->th_sport; - bzero((caddr_t)sin->sin_zero, sizeof(sin->sin_zero)); - laddr = inp->inp_laddr; - if (inp->inp_laddr.s_addr == INADDR_ANY) - inp->inp_laddr = ip->ip_dst; - if (in_pcbconnect(inp, (struct sockaddr *)sin, &proc0)) { - inp->inp_laddr = laddr; - FREE(sin, M_SONAME); - goto drop; - } - FREE(sin, M_SONAME); + int dropsocket = 0; + int iss = 0, nosock = 0; + u_int32_t tiwin, sack_bytes_acked = 0; + struct tcpopt to; /* options in this segment */ +#if TCPDEBUG + short ostate = 0; +#endif +#if IPFIREWALL + struct sockaddr_in *next_hop = NULL; + struct m_tag *fwd_tag; +#endif /* IPFIREWALL */ + u_char ip_ecn = IPTOS_ECN_NOTECT; + unsigned int ifscope; + uint8_t isconnected, isdisconnected; + struct ifnet *ifp = m->m_pkthdr.rcvif; + int pktf_sw_lro_pkt = (m->m_pkthdr.pkt_flags & PKTF_SW_LRO_PKT) ? 1 : 0; + int nlropkts = (pktf_sw_lro_pkt == 1) ? m->m_pkthdr.lro_npkts : 1; + int turnoff_lro = 0, win; +#if MPTCP + struct mptcb *mp_tp = NULL; +#endif /* MPTCP */ + boolean_t cell = IFNET_IS_CELLULAR(ifp); + boolean_t wifi = (!cell && IFNET_IS_WIFI(ifp)); + boolean_t wired = (!wifi && IFNET_IS_WIRED(ifp)); + boolean_t recvd_dsack = FALSE; + struct tcp_respond_args tra; + int prev_t_state; + boolean_t check_cfil = cfil_filter_present(); + bool findpcb_iterated = false; + /* + * The mbuf may be freed after it has been added to the receive socket + * buffer or the reassembly queue, so we reinitialize th to point to a + * safe copy of the TCP header + */ + struct tcphdr saved_tcphdr = {}; + /* + * Save copy of the IPv4/IPv6 header. + * Note: use array of uint32_t to silence compiler warning when casting + * to a struct ip6_hdr pointer. + */ +#define MAX_IPWORDS ((sizeof(struct ip) + MAX_IPOPTLEN) / sizeof(uint32_t)) + uint32_t saved_hdr[MAX_IPWORDS]; + +#define TCP_INC_VAR(stat, npkts) do { \ + stat += npkts; \ +} while (0) + + TCP_INC_VAR(tcpstat.tcps_rcvtotal, nlropkts); +#if IPFIREWALL + /* Grab info from PACKET_TAG_IPFORWARD tag prepended to the chain. */ + if (!SLIST_EMPTY(&m->m_pkthdr.tags)) { + fwd_tag = m_tag_locate(m, KERNEL_MODULE_TAG_ID, + KERNEL_TAG_TYPE_IPFORWARD, NULL); + } else { + fwd_tag = NULL; + } + if (fwd_tag != NULL) { + struct ip_fwd_tag *ipfwd_tag = + (struct ip_fwd_tag *)(fwd_tag + 1); + + next_hop = ipfwd_tag->next_hop; + m_tag_delete(m, fwd_tag); + } +#endif /* IPFIREWALL */ + #if INET6 - } + struct ip6_hdr *ip6 = NULL; + int isipv6; #endif /* INET6 */ + int rstreason; /* For badport_bandlim accounting purposes */ + struct proc *proc0 = current_proc(); - tp->t_template = tcp_template(tp); - if (tp->t_template == 0) { - tp = tcp_drop(tp, ENOBUFS); - dropsocket = 0; /* socket is already gone */ - goto drop; - } - if ((taop = tcp_gettaocache(inp)) == NULL) { - taop = &tao_noncached; - bzero(taop, sizeof(*taop)); + KERNEL_DEBUG(DBG_FNC_TCP_INPUT | DBG_FUNC_START, 0, 0, 0, 0, 0); + +#if INET6 + isipv6 = (mtod(m, struct ip *)->ip_v == 6) ? 1 : 0; +#endif + bzero((char *)&to, sizeof(to)); + +#if INET6 + if (isipv6) { + /* + * Expect 32-bit aligned data pointer on + * strict-align platforms + */ + MBUF_STRICT_DATA_ALIGNMENT_CHECK_32(m); + + /* IP6_EXTHDR_CHECK() is already done at tcp6_input() */ + ip6 = mtod(m, struct ip6_hdr *); + tlen = sizeof(*ip6) + ntohs(ip6->ip6_plen) - off0; + th = (struct tcphdr *)(void *)((caddr_t)ip6 + off0); + + if (tcp_input_checksum(AF_INET6, m, th, off0, tlen)) { + TCP_LOG_DROP_PKT(ip6, th, ifp, "IPv6 bad tcp checksum"); + goto dropnosock; } - tcp_dooptions(tp, optp, optlen, th, &to); - if (th->th_flags & TH_SYN) - tcp_mss(tp, to.to_maxseg, isipv6); /* sets t_maxseg */ - if (iss) - tp->iss = iss; - else { -#ifdef TCP_COMPAT_42 - tcp_iss += TCP_ISSINCR/2; - tp->iss = tcp_iss; -#else - tp->iss = tcp_rndiss_next(); -#endif /* TCP_COMPAT_42 */ - } - tp->irs = th->th_seq; - tcp_sendseqinit(tp); - tcp_rcvseqinit(tp); + + KERNEL_DEBUG(DBG_LAYER_BEG, ((th->th_dport << 16) | th->th_sport), + (((ip6->ip6_src.s6_addr16[0]) << 16) | (ip6->ip6_dst.s6_addr16[0])), + th->th_seq, th->th_ack, th->th_win); /* - * Initialization of the tcpcb for transaction; - * set SND.WND = SEG.WND, - * initialize CCsend and CCrecv. + * Be proactive about unspecified IPv6 address in source. + * As we use all-zero to indicate unbounded/unconnected pcb, + * unspecified IPv6 address can be used to confuse us. + * + * Note that packets with unspecified IPv6 destination is + * already dropped in ip6_input. */ - tp->snd_wnd = tiwin; /* initial send-window */ - tp->cc_send = CC_INC(tcp_ccgen); - tp->cc_recv = to.to_cc; + if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { + /* XXX stat */ + IF_TCP_STATINC(ifp, unspecv6); + TCP_LOG_DROP_PKT(ip6, th, ifp, "src IPv6 address unspecified"); + goto dropnosock; + } + DTRACE_TCP5(receive, struct mbuf *, m, struct inpcb *, NULL, + struct ip6_hdr *, ip6, struct tcpcb *, NULL, + struct tcphdr *, th); + + ip_ecn = (ntohl(ip6->ip6_flow) >> 20) & IPTOS_ECN_MASK; + } else +#endif /* INET6 */ + { /* - * Perform TAO test on incoming CC (SEG.CC) option, if any. - * - compare SEG.CC against cached CC from the same host, - * if any. - * - if SEG.CC > chached value, SYN must be new and is accepted - * immediately: save new CC in the cache, mark the socket - * connected, enter ESTABLISHED state, turn on flag to - * send a SYN in the next segment. - * A virtual advertised window is set in rcv_adv to - * initialize SWS prevention. Then enter normal segment - * processing: drop SYN, process data and FIN. - * - otherwise do a normal 3-way handshake. - */ - if ((to.to_flag & TOF_CC) != 0) { - if (((tp->t_flags & TF_NOPUSH) != 0) && - taop->tao_cc != 0 && CC_GT(to.to_cc, taop->tao_cc)) { - - taop->tao_cc = to.to_cc; - if (tp->t_state != TCPS_ESTABLISHED) - current_active_connections++; + * Get IP and TCP header together in first mbuf. + * Note: IP leaves IP header in first mbuf. + */ + if (off0 > sizeof(struct ip)) { + ip_stripoptions(m); + off0 = sizeof(struct ip); + } + if (m->m_len < sizeof(struct tcpiphdr)) { + if ((m = m_pullup(m, sizeof(struct tcpiphdr))) == 0) { + tcpstat.tcps_rcvshort++; + return; + } + } - tp->t_state = TCPS_ESTABLISHED; + /* Expect 32-bit aligned data pointer on strict-align platforms */ + MBUF_STRICT_DATA_ALIGNMENT_CHECK_32(m); + + ip = mtod(m, struct ip *); + th = (struct tcphdr *)(void *)((caddr_t)ip + off0); + tlen = ip->ip_len; + + if (tcp_input_checksum(AF_INET, m, th, off0, tlen)) { + TCP_LOG_DROP_PKT(ip, th, ifp, "IPv4 bad tcp checksum"); + goto dropnosock; + } - /* - * If there is a FIN, or if there is data and the - * connection is local, then delay SYN,ACK(SYN) in - * the hope of piggy-backing it on a response - * segment. Otherwise must send ACK now in case - * the other side is slow starting. - */ - if (tcp_delack_enabled && - ((thflags & TH_FIN) || - (tilen != 0 && #if INET6 - (isipv6 && in6_localaddr(&inp->in6p_faddr)) - || - (!isipv6 && -#endif /* INET6 */ - in_localaddr(inp->inp_faddr) + /* Re-initialization for later version check */ + ip->ip_v = IPVERSION; +#endif + ip_ecn = (ip->ip_tos & IPTOS_ECN_MASK); + + DTRACE_TCP5(receive, struct mbuf *, m, struct inpcb *, NULL, + struct ip *, ip, struct tcpcb *, NULL, struct tcphdr *, th); + + KERNEL_DEBUG(DBG_LAYER_BEG, ((th->th_dport << 16) | th->th_sport), + (((ip->ip_src.s_addr & 0xffff) << 16) | (ip->ip_dst.s_addr & 0xffff)), + th->th_seq, th->th_ack, th->th_win); + } + +#define TCP_LOG_HDR (isipv6 ? (void *)ip6 : (void *)ip) + + /* + * Check that TCP offset makes sense, + * pull out TCP options and adjust length. + */ + off = th->th_off << 2; + if (off < sizeof(struct tcphdr) || off > tlen) { + tcpstat.tcps_rcvbadoff++; + IF_TCP_STATINC(ifp, badformat); + TCP_LOG_DROP_PKT(TCP_LOG_HDR, th, ifp, "bad tcp offset"); + goto dropnosock; + } + tlen -= off; /* tlen is used instead of ti->ti_len */ + if (off > sizeof(struct tcphdr)) { #if INET6 - ) + if (isipv6) { + IP6_EXTHDR_CHECK(m, off0, off, return ); + ip6 = mtod(m, struct ip6_hdr *); + th = (struct tcphdr *)(void *)((caddr_t)ip6 + off0); + } else #endif /* INET6 */ - ))) { - if (last_active_conn_count > DELACK_BITMASK_THRESH) - TCP_DELACK_BITSET(tp->t_inpcb->hash_element); - - tp->t_flags |= (TF_DELACK | TF_NEEDSYN); + { + if (m->m_len < sizeof(struct ip) + off) { + if ((m = m_pullup(m, sizeof(struct ip) + off)) == 0) { + tcpstat.tcps_rcvshort++; + return; + } + ip = mtod(m, struct ip *); + th = (struct tcphdr *)(void *)((caddr_t)ip + off0); } - else - tp->t_flags |= (TF_ACKNOW | TF_NEEDSYN); - - /* - * Limit the `virtual advertised window' to TCP_MAXWIN - * here. Even if we requested window scaling, it will - * become effective only later when our SYN is acked. - */ - tp->rcv_adv += min(tp->rcv_wnd, TCP_MAXWIN); - tcpstat.tcps_connects++; - soisconnected(so); - tp->t_timer[TCPT_KEEP] = tcp_keepinit; - dropsocket = 0; /* committed to socket */ - tcpstat.tcps_accepts++; - goto trimthenstep6; - } - /* else do standard 3-way handshake */ - } else { - /* - * No CC option, but maybe CC.NEW: - * invalidate cached value. - */ - taop->tao_cc = 0; } + optlen = off - sizeof(struct tcphdr); + optp = (u_char *)(th + 1); /* - * TAO test failed or there was no CC option, - * do a standard 3-way handshake. + * Do quick retrieval of timestamp options ("options + * prediction?"). If timestamp is the only option and it's + * formatted as recommended in RFC 1323 appendix A, we + * quickly get the values now and not bother calling + * tcp_dooptions(), etc. */ - tp->t_flags |= TF_ACKNOW; - tp->t_state = TCPS_SYN_RECEIVED; - tp->t_timer[TCPT_KEEP] = tcp_keepinit; - dropsocket = 0; /* committed to socket */ - tcpstat.tcps_accepts++; - goto trimthenstep6; + if ((optlen == TCPOLEN_TSTAMP_APPA || + (optlen > TCPOLEN_TSTAMP_APPA && + optp[TCPOLEN_TSTAMP_APPA] == TCPOPT_EOL)) && + *(u_int32_t *)(void *)optp == htonl(TCPOPT_TSTAMP_HDR) && + (th->th_flags & TH_SYN) == 0) { + to.to_flags |= TOF_TS; + to.to_tsval = ntohl(*(u_int32_t *)(void *)(optp + 4)); + to.to_tsecr = ntohl(*(u_int32_t *)(void *)(optp + 8)); + optp = NULL; /* we've parsed the options */ } + } + thflags = th->th_flags; +#if TCP_DROP_SYNFIN /* - * If the state is SYN_RECEIVED: - * if seg contains an ACK, but not for our SYN/ACK, send a RST. + * If the drop_synfin option is enabled, drop all packets with + * both the SYN and FIN bits set. This prevents e.g. nmap from + * identifying the TCP/IP stack. + * + * This is a violation of the TCP specification. */ - case TCPS_SYN_RECEIVED: - if ((thflags & TH_ACK) && - (SEQ_LEQ(th->th_ack, tp->snd_una) || - SEQ_GT(th->th_ack, tp->snd_max))) - goto dropwithreset; - break; + if (drop_synfin && (thflags & (TH_SYN | TH_FIN)) == (TH_SYN | TH_FIN)) { + IF_TCP_STATINC(ifp, synfin); + TCP_LOG_DROP_PKT(TCP_LOG_HDR, th, ifp, "drop SYN FIN"); + goto dropnosock; + } +#endif /* - * If the state is SYN_SENT: - * if seg contains an ACK, but not for our SYN, drop the input. - * if seg contains a RST, then drop the connection. - * if seg does not contain SYN, then drop it. - * Otherwise this is an acceptable SYN segment - * initialize tp->rcv_nxt and tp->irs - * if seg contains ack then advance tp->snd_una - * if SYN has been acked change to ESTABLISHED else SYN_RCVD state - * arrange for segment to be acked (eventually) - * continue processing rest of data/controls, beginning with URG + * Delay dropping TCP, IP headers, IPv6 ext headers, and TCP options, + * until after ip6_savecontrol() is called and before other functions + * which don't want those proto headers. + * Because ip6_savecontrol() is going to parse the mbuf to + * search for data to be passed up to user-land, it wants mbuf + * parameters to be unchanged. */ - case TCPS_SYN_SENT: - if ((taop = tcp_gettaocache(inp)) == NULL) { - taop = &tao_noncached; - bzero(taop, sizeof(*taop)); - } + drop_hdrlen = off0 + off; - if ((thflags & TH_ACK) && - (SEQ_LEQ(th->th_ack, tp->iss) || - SEQ_GT(th->th_ack, tp->snd_max))) { - /* - * If we have a cached CCsent for the remote host, - * hence we haven't just crashed and restarted, - * do not send a RST. This may be a retransmission - * from the other side after our earlier ACK was lost. - * Our new SYN, when it arrives, will serve as the - * needed ACK. - */ - if (taop->tao_ccsent != 0) - goto drop; - else - goto dropwithreset; - } - if (thflags & TH_RST) { - if (thflags & TH_ACK) { - tp = tcp_drop(tp, ECONNREFUSED); - postevent(so, 0, EV_RESET); - } - goto drop; - } - if ((thflags & TH_SYN) == 0) - goto drop; - tp->snd_wnd = th->th_win; /* initial send window */ - tp->cc_recv = to.to_cc; /* foreign CC */ + /* Since this is an entry point for input processing of tcp packets, we + * can update the tcp clock here. + */ + calculate_tcp_clock(); - tp->irs = th->th_seq; - tcp_rcvseqinit(tp); - if (thflags & TH_ACK) { - /* - * Our SYN was acked. If segment contains CC.ECHO - * option, check it to make sure this segment really - * matches our SYN. If not, just drop it as old - * duplicate, but send an RST if we're still playing - * by the old rules. If no CC.ECHO option, make sure - * we don't get fooled into using T/TCP. - */ - if (to.to_flag & TOF_CCECHO) { - if (tp->cc_send != to.to_ccecho) - if (taop->tao_ccsent != 0) - goto drop; - else - goto dropwithreset; - } else - tp->t_flags &= ~TF_RCVD_CC; - tcpstat.tcps_connects++; - soisconnected(so); - /* Do window scaling on this connection? */ - if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == - (TF_RCVD_SCALE|TF_REQ_SCALE)) { - tp->snd_scale = tp->requested_s_scale; - tp->rcv_scale = tp->request_r_scale; - } - /* Segment is acceptable, update cache if undefined. */ - if (taop->tao_ccsent == 0) - taop->tao_ccsent = to.to_ccecho; + /* + * Record the interface where this segment arrived on; this does not + * affect normal data output (for non-detached TCP) as it provides a + * hint about which route and interface to use for sending in the + * absence of a PCB, when scoped routing (and thus source interface + * selection) are enabled. + */ + if ((m->m_pkthdr.pkt_flags & PKTF_LOOP) || m->m_pkthdr.rcvif == NULL) { + ifscope = IFSCOPE_NONE; + } else { + ifscope = m->m_pkthdr.rcvif->if_index; + } + + /* + * Convert TCP protocol specific fields to host format. + */ + +#if BYTE_ORDER != BIG_ENDIAN + NTOHL(th->th_seq); + NTOHL(th->th_ack); + NTOHS(th->th_win); + NTOHS(th->th_urp); +#endif + + /* + * Locate pcb for segment. + */ +findpcb: + + isconnected = FALSE; + isdisconnected = FALSE; - tp->rcv_adv += tp->rcv_wnd; - tp->snd_una++; /* SYN is acked */ +#if IPFIREWALL_FORWARD + if (next_hop != NULL +#if INET6 + && isipv6 == 0 /* IPv6 support is not yet */ +#endif /* INET6 */ + ) { + /* + * Diverted. Pretend to be the destination. + * already got one like this? + */ + inp = in_pcblookup_hash(&tcbinfo, ip->ip_src, th->th_sport, + ip->ip_dst, th->th_dport, 0, m->m_pkthdr.rcvif); + if (!inp) { /* - * If there's data, delay ACK; if there's also a FIN - * ACKNOW will be turned on later. + * No, then it's new. Try find the ambushing socket */ - if (tcp_delack_enabled && tilen != 0) { - if (last_active_conn_count > DELACK_BITMASK_THRESH) - TCP_DELACK_BITSET(tp->t_inpcb->hash_element); - tp->t_flags |= TF_DELACK; - } - else - tp->t_flags |= TF_ACKNOW; - /* - * Received in SYN_SENT[*] state. - * Transitions: - * SYN_SENT --> ESTABLISHED - * SYN_SENT* --> FIN_WAIT_1 - */ - if (tp->t_flags & TF_NEEDFIN) { - tp->t_state = TCPS_FIN_WAIT_1; - tp->t_flags &= ~TF_NEEDFIN; - thflags &= ~TH_SYN; - } else { - if (tp->t_state != TCPS_ESTABLISHED) - current_active_connections++; - tp->t_state = TCPS_ESTABLISHED; - tp->t_timer[TCPT_KEEP] = tcp_keepidle; - } - } else { - /* - * Received initial SYN in SYN-SENT[*] state => simul- - * taneous open. If segment contains CC option and there is - * a cached CC, apply TAO test; if it succeeds, connection is - * half-synchronized. Otherwise, do 3-way handshake: - * SYN-SENT -> SYN-RECEIVED - * SYN-SENT* -> SYN-RECEIVED* - * If there was no CC option, clear cached CC value. - */ - tp->t_flags |= TF_ACKNOW; - tp->t_timer[TCPT_REXMT] = 0; - if (to.to_flag & TOF_CC) { - if (taop->tao_cc != 0 && - CC_GT(to.to_cc, taop->tao_cc)) { - /* - * update cache and make transition: - * SYN-SENT -> ESTABLISHED* - * SYN-SENT* -> FIN-WAIT-1* - */ - taop->tao_cc = to.to_cc; - if (tp->t_flags & TF_NEEDFIN) { - tp->t_state = TCPS_FIN_WAIT_1; - tp->t_flags &= ~TF_NEEDFIN; - } else { - if (tp->t_state != TCPS_ESTABLISHED) - current_active_connections++; - tp->t_state = TCPS_ESTABLISHED; - tp->t_timer[TCPT_KEEP] = tcp_keepidle; - } - tp->t_flags |= TF_NEEDSYN; - } else - tp->t_state = TCPS_SYN_RECEIVED; + if (!next_hop->sin_port) { + inp = in_pcblookup_hash(&tcbinfo, ip->ip_src, + th->th_sport, next_hop->sin_addr, + th->th_dport, 1, m->m_pkthdr.rcvif); } else { - /* CC.NEW or no option => invalidate cache */ - taop->tao_cc = 0; - tp->t_state = TCPS_SYN_RECEIVED; + inp = in_pcblookup_hash(&tcbinfo, + ip->ip_src, th->th_sport, + next_hop->sin_addr, + ntohs(next_hop->sin_port), 1, + m->m_pkthdr.rcvif); } } + } else +#endif /* IPFIREWALL_FORWARD */ + { +#if INET6 + if (isipv6) { + inp = in6_pcblookup_hash(&tcbinfo, &ip6->ip6_src, th->th_sport, + &ip6->ip6_dst, th->th_dport, 1, + m->m_pkthdr.rcvif); + } else +#endif /* INET6 */ + inp = in_pcblookup_hash(&tcbinfo, ip->ip_src, th->th_sport, + ip->ip_dst, th->th_dport, 1, m->m_pkthdr.rcvif); + } -trimthenstep6: - /* - * Advance th->th_seq to correspond to first data byte. - * If data, trim to stay within window, - * dropping FIN if necessary. - */ - th->th_seq++; - if (tilen > tp->rcv_wnd) { - todrop = tilen - tp->rcv_wnd; - m_adj(m, -todrop); - tilen = tp->rcv_wnd; - thflags &= ~TH_FIN; - tcpstat.tcps_rcvpackafterwin++; - tcpstat.tcps_rcvbyteafterwin += todrop; - } - tp->snd_wl1 = th->th_seq - 1; - tp->rcv_up = th->th_seq; - /* - * Client side of transaction: already sent SYN and data. - * If the remote host used T/TCP to validate the SYN, - * our data will be ACK'd; if so, enter normal data segment - * processing in the middle of step 5, ack processing. - * Otherwise, goto step 6. - */ - if (thflags & TH_ACK) - goto process_ACK; - goto step6; /* - * If the state is LAST_ACK or CLOSING or TIME_WAIT: - * if segment contains a SYN and CC [not CC.NEW] option: - * if state == TIME_WAIT and connection duration > MSL, - * drop packet and send RST; - * - * if SEG.CC > CCrecv then is new SYN, and can implicitly - * ack the FIN (and data) in retransmission queue. - * Complete close and delete TCPCB. Then reprocess - * segment, hoping to find new TCPCB in LISTEN state; - * - * else must be old SYN; drop it. - * else do normal processing. + * Use the interface scope information from the PCB for outbound + * segments. If the PCB isn't present and if scoped routing is + * enabled, tcp_respond will use the scope of the interface where + * the segment arrived on. */ - case TCPS_LAST_ACK: - case TCPS_CLOSING: - case TCPS_TIME_WAIT: - if ((thflags & TH_SYN) && - (to.to_flag & TOF_CC) && tp->cc_recv != 0) { - if (tp->t_state == TCPS_TIME_WAIT && - tp->t_duration > TCPTV_MSL) - goto dropwithreset; - if (CC_GT(to.to_cc, tp->cc_recv)) { - tp = tcp_close(tp); - goto findpcb; - } - else - goto drop; - } - break; /* continue normal processing */ + if (inp != NULL && (inp->inp_flags & INP_BOUND_IF)) { + ifscope = inp->inp_boundifp->if_index; } /* - * States other than LISTEN or SYN_SENT. - * First check the RST flag and sequence number since reset segments - * are exempt from the timestamp and connection count tests. This - * fixes a bug introduced by the Stevens, vol. 2, p. 960 bugfix - * below which allowed reset segments in half the sequence space - * to fall though and be processed (which gives forged reset - * segments with a random sequence number a 50 percent chance of - * killing a connection). - * Then check timestamp, if present. - * Then check the connection count, if present. - * Then check that at least some bytes of segment are within - * receive window. If segment begins before rcv_nxt, - * drop leading data (and SYN); if nothing left, just ack. - * - * - * If the RST bit is set, check the sequence number to see - * if this is a valid reset segment. - * RFC 793 page 37: - * In all states except SYN-SENT, all reset (RST) segments - * are validated by checking their SEQ-fields. A reset is - * valid if its sequence number is in the window. - * Note: this does not take into account delayed ACKs, so - * we should test against last_ack_sent instead of rcv_nxt. - * Also, it does not make sense to allow reset segments with - * sequence numbers greater than last_ack_sent to be processed - * since these sequence numbers are just the acknowledgement - * numbers in our outgoing packets being echoed back at us, - * and these acknowledgement numbers are monotonically - * increasing. - * If we have multiple segments in flight, the intial reset - * segment sequence numbers will be to the left of last_ack_sent, - * but they will eventually catch up. - * In any case, it never made sense to trim reset segments to - * fit the receive window since RFC 1122 says: - * 4.2.2.12 RST Segment: RFC-793 Section 3.4 - * - * A TCP SHOULD allow a received RST segment to include data. - * - * DISCUSSION - * It has been suggested that a RST segment could contain - * ASCII text that encoded and explained the cause of the - * RST. No standard has yet been established for such - * data. - * - * If the reset segment passes the sequence number test examine - * the state: - * SYN_RECEIVED STATE: - * If passive open, return to LISTEN state. - * If active open, inform user that connection was refused. - * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES: - * Inform user that connection was reset, and close tcb. - * CLOSING, LAST_ACK, TIME_WAIT STATES - * Close the tcb. - * TIME_WAIT state: - * Drop the segment - see Stevens, vol. 2, p. 964 and - * RFC 1337. + * If the state is CLOSED (i.e., TCB does not exist) then + * all data in the incoming segment is discarded. + * If the TCB exists but is in CLOSED state, it is embryonic, + * but should either do a listen or a connect soon. */ - if (thflags & TH_RST) { - if (tp->last_ack_sent == th->th_seq) { - switch (tp->t_state) { - - case TCPS_SYN_RECEIVED: - so->so_error = ECONNREFUSED; - goto close; + if (inp == NULL) { + if (log_in_vain) { +#if INET6 + char dbuf[MAX_IPv6_STR_LEN], sbuf[MAX_IPv6_STR_LEN]; +#else /* INET6 */ + char dbuf[MAX_IPv4_STR_LEN], sbuf[MAX_IPv4_STR_LEN]; +#endif /* INET6 */ - case TCPS_ESTABLISHED: - case TCPS_FIN_WAIT_1: - case TCPS_CLOSE_WAIT: - current_active_connections--; - /* - Drop through ... - */ - case TCPS_FIN_WAIT_2: - so->so_error = ECONNRESET; - close: - postevent(so, 0, EV_RESET); - tp->t_state = TCPS_CLOSED; - tcpstat.tcps_drops++; - tp = tcp_close(tp); +#if INET6 + if (isipv6) { + inet_ntop(AF_INET6, &ip6->ip6_dst, dbuf, sizeof(dbuf)); + inet_ntop(AF_INET6, &ip6->ip6_src, sbuf, sizeof(sbuf)); + } else +#endif + { + inet_ntop(AF_INET, &ip->ip_dst, dbuf, sizeof(dbuf)); + inet_ntop(AF_INET, &ip->ip_src, sbuf, sizeof(sbuf)); + } + switch (log_in_vain) { + case 1: + if (thflags & TH_SYN) { + log(LOG_INFO, + "Connection attempt to TCP %s:%d from %s:%d\n", + dbuf, ntohs(th->th_dport), + sbuf, + ntohs(th->th_sport)); + } break; - - case TCPS_CLOSING: - case TCPS_LAST_ACK: - current_active_connections--; - tp = tcp_close(tp); + case 2: + log(LOG_INFO, + "Connection attempt to TCP %s:%d from %s:%d flags:0x%x\n", + dbuf, ntohs(th->th_dport), sbuf, + ntohs(th->th_sport), thflags); break; - - case TCPS_TIME_WAIT: + case 3: + case 4: + if ((thflags & TH_SYN) && !(thflags & TH_ACK) && + !(m->m_flags & (M_BCAST | M_MCAST)) && +#if INET6 + ((isipv6 && !IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &ip6->ip6_src)) || + (!isipv6 && ip->ip_dst.s_addr != ip->ip_src.s_addr)) +#else + ip->ip_dst.s_addr != ip->ip_src.s_addr +#endif + ) { + log_in_vain_log((LOG_INFO, + "Stealth Mode connection attempt to TCP %s:%d from %s:%d\n", + dbuf, ntohs(th->th_dport), + sbuf, + ntohs(th->th_sport))); + } + break; + default: break; } } - goto drop; + if (blackhole) { + if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type != IFT_LOOP) { + switch (blackhole) { + case 1: + if (thflags & TH_SYN) { + TCP_LOG_DROP_PKT(TCP_LOG_HDR, th, ifp, "blackhole 1 syn for closed port"); + goto dropnosock; + } + break; + case 2: + TCP_LOG_DROP_PKT(TCP_LOG_HDR, th, ifp, "blackhole 2 closed port"); + goto dropnosock; + default: + TCP_LOG_DROP_PKT(TCP_LOG_HDR, th, ifp, "blackhole closed port"); + goto dropnosock; + } + } + } + rstreason = BANDLIM_RST_CLOSEDPORT; + IF_TCP_STATINC(ifp, noconnnolist); + TCP_LOG_DROP_PKT(TCP_LOG_HDR, th, ifp, "closed port"); + goto dropwithresetnosock; + } + so = inp->inp_socket; + if (so == NULL) { + /* This case shouldn't happen as the socket shouldn't be null + * if inp_state isn't set to INPCB_STATE_DEAD + * But just in case, we pretend we didn't find the socket if we hit this case + * as this isn't cause for a panic (the socket might be leaked however)... + */ + inp = NULL; +#if TEMPDEBUG + printf("tcp_input: no more socket for inp=%x. This shouldn't happen\n", inp); +#endif + TCP_LOG_DROP_PKT(TCP_LOG_HDR, th, ifp, "inp_socket NULL"); + goto dropnosock; } - /* - * RFC 1323 PAWS: If we have a timestamp reply on this segment - * and it's less than ts_recent, drop it. - */ - if ((to.to_flag & TOF_TS) != 0 && tp->ts_recent && - TSTMP_LT(to.to_tsval, tp->ts_recent)) { + socket_lock(so, 1); + if (in_pcb_checkstate(inp, WNT_RELEASE, 1) == WNT_STOPUSING) { + socket_unlock(so, 1); + inp = NULL; // pretend we didn't find it + TCP_LOG_DROP_PKT(TCP_LOG_HDR, th, ifp, "inp state WNT_STOPUSING"); + goto dropnosock; + } - /* Check to see if ts_recent is over 24 days old. */ - if ((int)(tcp_now - tp->ts_recent_age) > TCP_PAWS_IDLE) { - /* - * Invalidate ts_recent. If this segment updates - * ts_recent, the age will be reset later and ts_recent - * will get a valid value. If it does not, setting - * ts_recent to zero will at least satisfy the - * requirement that zero be placed in the timestamp - * echo reply when ts_recent isn't valid. The - * age isn't reset until we get a valid ts_recent - * because we don't want out-of-order segments to be - * dropped when ts_recent is old. - */ - tp->ts_recent = 0; - } else { - tcpstat.tcps_rcvduppack++; - tcpstat.tcps_rcvdupbyte += tilen; - tcpstat.tcps_pawsdrop++; - goto dropafterack; + if (!isipv6 && inp->inp_faddr.s_addr != INADDR_ANY) { + if (inp->inp_faddr.s_addr != ip->ip_src.s_addr || + inp->inp_laddr.s_addr != ip->ip_dst.s_addr || + inp->inp_fport != th->th_sport || + inp->inp_lport != th->th_dport) { + os_log_error(OS_LOG_DEFAULT, "%s 5-tuple does not match: %u:%u %u:%u\n", + __func__, + ntohs(inp->inp_fport), ntohs(th->th_sport), + ntohs(inp->inp_lport), ntohs(th->th_dport)); + if (findpcb_iterated) { + goto drop; + } + findpcb_iterated = true; + socket_unlock(so, 1); + inp = NULL; + goto findpcb; + } + } else if (isipv6 && !IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_faddr)) { + if (!IN6_ARE_ADDR_EQUAL(&inp->in6p_faddr, &ip6->ip6_src) || + !IN6_ARE_ADDR_EQUAL(&inp->in6p_laddr, &ip6->ip6_dst) || + inp->inp_fport != th->th_sport || + inp->inp_lport != th->th_dport) { + os_log_error(OS_LOG_DEFAULT, "%s 5-tuple does not match: %u:%u %u:%u\n", + __func__, + ntohs(inp->inp_fport), ntohs(th->th_sport), + ntohs(inp->inp_lport), ntohs(th->th_dport)); + if (findpcb_iterated) { + goto drop; + } + findpcb_iterated = true; + socket_unlock(so, 1); + inp = NULL; + goto findpcb; } } - /* - * T/TCP mechanism - * If T/TCP was negotiated and the segment doesn't have CC, - * or if its CC is wrong then drop the segment. - * RST segments do not have to comply with this. - */ - if ((tp->t_flags & (TF_REQ_CC|TF_RCVD_CC)) == (TF_REQ_CC|TF_RCVD_CC) && - ((to.to_flag & TOF_CC) == 0 || tp->cc_recv != to.to_cc)) - goto dropafterack; - - /* - * In the SYN-RECEIVED state, validate that the packet belongs to - * this connection before trimming the data to fit the receive - * window. Check the sequence number versus IRS since we know - * the sequence numbers haven't wrapped. This is a partial fix - * for the "LAND" DoS attack. - */ - if (tp->t_state == TCPS_SYN_RECEIVED && SEQ_LT(th->th_seq, tp->irs)) + tp = intotcpcb(inp); + if (tp == NULL) { + rstreason = BANDLIM_RST_CLOSEDPORT; + IF_TCP_STATINC(ifp, noconnlist); + TCP_LOG_DROP_PKT(TCP_LOG_HDR, th, ifp, "tp is NULL"); goto dropwithreset; + } - todrop = tp->rcv_nxt - th->th_seq; - if (todrop > 0) { - if (thflags & TH_SYN) { - thflags &= ~TH_SYN; - th->th_seq++; - if (th->th_urp > 1) - th->th_urp--; - else - thflags &= ~TH_URG; - todrop--; + TCP_LOG_TH_FLAGS(TCP_LOG_HDR, th, tp, false, ifp); + + if (tp->t_state == TCPS_CLOSED) { + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "tp state TCPS_CLOSED"); + goto drop; + } + +#if NECP + if (so->so_state & SS_ISCONNECTED) { + // Connected TCP sockets have a fully-bound local and remote, + // so the policy check doesn't need to override addresses + if (!necp_socket_is_allowed_to_send_recv(inp, ifp, NULL, NULL, NULL)) { + TCP_LOG_DROP_NECP(TCP_LOG_HDR, th, intotcpcb(inp), false); + IF_TCP_STATINC(ifp, badformat); + goto drop; } + } else { /* - * Following if statement from Stevens, vol. 2, p. 960. + * If the proc_uuid_policy table has been updated since the last use + * of the listening socket (i.e., the proc_uuid_policy_table_gencount + * has been updated), the flags in the socket may be out of date. + * If INP2_WANT_APP_POLICY is stale, inbound packets may + * be dropped by NECP if the socket should now match a per-app + * exception policy. + * In order to avoid this refresh the proc_uuid_policy state to + * potentially recalculate the socket's flags before checking + * with NECP. */ - if (todrop > tilen - || (todrop == tilen && (thflags & TH_FIN) == 0)) { - /* - * Any valid FIN must be to the left of the window. - * At this point the FIN must be a duplicate or out - * of sequence; drop it. - */ - thflags &= ~TH_FIN; - - /* - * Send an ACK to resynchronize and drop any data. - * But keep on processing for RST or ACK. - */ - tp->t_flags |= TF_ACKNOW; - todrop = tilen; - tcpstat.tcps_rcvduppack++; - tcpstat.tcps_rcvdupbyte += todrop; - } else { - tcpstat.tcps_rcvpartduppack++; - tcpstat.tcps_rcvpartdupbyte += todrop; - } - m_adj(m, todrop); - th->th_seq += todrop; - tilen -= todrop; - if (th->th_urp > todrop) - th->th_urp -= todrop; - else { - thflags &= ~TH_URG; - th->th_urp = 0; + (void) inp_update_policy(inp); +#if INET6 + if (isipv6) { + if (!necp_socket_is_allowed_to_send_recv_v6(inp, + th->th_dport, th->th_sport, &ip6->ip6_dst, + &ip6->ip6_src, ifp, NULL, NULL, NULL)) { + TCP_LOG_DROP_NECP(TCP_LOG_HDR, th, intotcpcb(inp), false); + IF_TCP_STATINC(ifp, badformat); + goto drop; + } + } else +#endif + { + if (!necp_socket_is_allowed_to_send_recv_v4(inp, + th->th_dport, th->th_sport, &ip->ip_dst, &ip->ip_src, + ifp, NULL, NULL, NULL)) { + TCP_LOG_DROP_NECP(TCP_LOG_HDR, th, intotcpcb(inp), false); + IF_TCP_STATINC(ifp, badformat); + goto drop; + } } } +#endif /* NECP */ - /* - * If new data are received on a connection after the - * user processes are gone, then RST the other end. - */ - if ((so->so_state & SS_NOFDREF) && - tp->t_state > TCPS_CLOSE_WAIT && tilen) { - tp = tcp_close(tp); - tcpstat.tcps_rcvafterclose++; - goto dropwithreset; + prev_t_state = tp->t_state; + + /* If none of the FIN|SYN|RST|ACK flag is set, drop */ + if (tcp_do_rfc5961 && (thflags & TH_ACCEPT) == 0) { + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "rfc5961 TH_ACCEPT == 0"); + goto drop; } - /* - * If segment ends after window, drop trailing data - * (and PUSH and FIN); if nothing left, just ACK. - */ - todrop = (th->th_seq+tilen) - (tp->rcv_nxt+tp->rcv_wnd); - if (todrop > 0) { - tcpstat.tcps_rcvpackafterwin++; - if (todrop >= tilen) { - tcpstat.tcps_rcvbyteafterwin += tilen; - /* - * If a new connection request is received - * while in TIME_WAIT, drop the old connection - * and start over if the sequence numbers - * are above the previous ones. + /* Unscale the window into a 32-bit value. */ + if ((thflags & TH_SYN) == 0) { + tiwin = th->th_win << tp->snd_scale; + } else { + tiwin = th->th_win; + } + + +#if CONFIG_MACF_NET + if (mac_inpcb_check_deliver(inp, m, AF_INET, SOCK_STREAM)) { + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "mac_inpcb_check_deliver failed"); + goto drop; + } +#endif + + /* Avoid processing packets while closing a listen socket */ + if (tp->t_state == TCPS_LISTEN && + (so->so_options & SO_ACCEPTCONN) == 0) { + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "closing a listening socket"); + goto drop; + } + + if (so->so_options & (SO_DEBUG | SO_ACCEPTCONN)) { +#if TCPDEBUG + if (so->so_options & SO_DEBUG) { + ostate = tp->t_state; +#if INET6 + if (isipv6) { + bcopy((char *)ip6, (char *)tcp_saveipgen, + sizeof(*ip6)); + } else +#endif /* INET6 */ + bcopy((char *)ip, (char *)tcp_saveipgen, sizeof(*ip)); + tcp_savetcp = *th; + } +#endif + if (so->so_options & SO_ACCEPTCONN) { + struct tcpcb *tp0 = tp; + struct socket *so2; + struct socket *oso; + struct sockaddr_storage from; + struct sockaddr_storage to2; +#if INET6 + struct inpcb *oinp = sotoinpcb(so); +#endif /* INET6 */ + struct ifnet *head_ifscope; + unsigned int head_nocell, head_recvanyif, + head_noexpensive, head_awdl_unrestricted, + head_intcoproc_allowed, head_external_port, + head_noconstrained; + + /* Get listener's bound-to-interface, if any */ + head_ifscope = (inp->inp_flags & INP_BOUND_IF) ? + inp->inp_boundifp : NULL; + /* Get listener's no-cellular information, if any */ + head_nocell = INP_NO_CELLULAR(inp); + /* Get listener's recv-any-interface, if any */ + head_recvanyif = (inp->inp_flags & INP_RECV_ANYIF); + /* Get listener's no-expensive information, if any */ + head_noexpensive = INP_NO_EXPENSIVE(inp); + head_noconstrained = INP_NO_CONSTRAINED(inp); + head_awdl_unrestricted = INP_AWDL_UNRESTRICTED(inp); + head_intcoproc_allowed = INP_INTCOPROC_ALLOWED(inp); + head_external_port = (inp->inp_flags2 & INP2_EXTERNAL_PORT); + + /* + * If the state is LISTEN then ignore segment if it contains an RST. + * If the segment contains an ACK then it is bad and send a RST. + * If it does not contain a SYN then it is not interesting; drop it. + * If it is from this socket, drop it, it must be forged. */ - if (thflags & TH_SYN && - tp->t_state == TCPS_TIME_WAIT && - SEQ_GT(th->th_seq, tp->rcv_nxt)) { -#ifdef TCP_COMPAT_42 - iss = tp->rcv_nxt + TCP_ISSINCR; -#else - iss = tcp_rndiss_next(); -#endif /* TCP_COMPAT_42 */ - tp = tcp_close(tp); - goto findpcb; + if ((thflags & (TH_RST | TH_ACK | TH_SYN)) != TH_SYN) { + IF_TCP_STATINC(ifp, listbadsyn); + + if (thflags & TH_RST) { + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "SYN with RST"); + goto drop; + } + if (thflags & TH_ACK) { + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "SYN with ACK"); + tp = NULL; + tcpstat.tcps_badsyn++; + rstreason = BANDLIM_RST_OPENPORT; + goto dropwithreset; + } + + /* We come here if there is no SYN set */ + tcpstat.tcps_badsyn++; + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "bad SYN"); + goto drop; + } + KERNEL_DEBUG(DBG_FNC_TCP_NEWCONN | DBG_FUNC_START, 0, 0, 0, 0, 0); + if (th->th_dport == th->th_sport) { +#if INET6 + if (isipv6) { + if (IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, + &ip6->ip6_src)) { + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "bad tuple same port"); + goto drop; + } + } else +#endif /* INET6 */ + if (ip->ip_dst.s_addr == ip->ip_src.s_addr) { + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "bad tuple same IPv4 address"); + goto drop; + } } /* - * If window is closed can only take segments at - * window edge, and have to drop data and PUSH from - * incoming segments. Continue processing, but - * remember to ack. Otherwise, drop segment - * and ack. + * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN + * in_broadcast() should never return true on a received + * packet with M_BCAST not set. + * + * Packets with a multicast source address should also + * be discarded. */ - if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { - tp->t_flags |= TF_ACKNOW; - tcpstat.tcps_rcvwinprobe++; + if (m->m_flags & (M_BCAST | M_MCAST)) { + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "mbuf M_BCAST | M_MCAST"); + goto drop; + } +#if INET6 + if (isipv6) { + if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || + IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) { + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "IN6_IS_ADDR_MULTICAST"); + goto drop; + } } else - goto dropafterack; - } else - tcpstat.tcps_rcvbyteafterwin += todrop; - m_adj(m, -todrop); - tilen -= todrop; - thflags &= ~(TH_PUSH|TH_FIN); +#endif + if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || + IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || + ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || + in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) { + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "multicast or broadcast address"); + goto drop; + } + + +#if INET6 + /* + * If deprecated address is forbidden, + * we do not accept SYN to deprecated interface + * address to prevent any new inbound connection from + * getting established. + * When we do not accept SYN, we send a TCP RST, + * with deprecated source address (instead of dropping + * it). We compromise it as it is much better for peer + * to send a RST, and RST will be the final packet + * for the exchange. + * + * If we do not forbid deprecated addresses, we accept + * the SYN packet. RFC 4862 forbids dropping SYN in + * this case. + */ + if (isipv6 && !ip6_use_deprecated) { + uint32_t ia6_flags; + + if (ip6_getdstifaddr_info(m, NULL, + &ia6_flags) == 0) { + if (ia6_flags & IN6_IFF_DEPRECATED) { + tp = NULL; + rstreason = BANDLIM_RST_OPENPORT; + IF_TCP_STATINC(ifp, deprecate6); + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "deprecated IPv6 address"); + goto dropwithreset; + } + } + } +#endif + if (so->so_filt || check_cfil) { +#if INET6 + if (isipv6) { + struct sockaddr_in6 *sin6 = (struct sockaddr_in6*)&from; + + sin6->sin6_len = sizeof(*sin6); + sin6->sin6_family = AF_INET6; + sin6->sin6_port = th->th_sport; + sin6->sin6_flowinfo = 0; + sin6->sin6_addr = ip6->ip6_src; + sin6->sin6_scope_id = 0; + + sin6 = (struct sockaddr_in6*)&to2; + + sin6->sin6_len = sizeof(struct sockaddr_in6); + sin6->sin6_family = AF_INET6; + sin6->sin6_port = th->th_dport; + sin6->sin6_flowinfo = 0; + sin6->sin6_addr = ip6->ip6_dst; + sin6->sin6_scope_id = 0; + } else +#endif + { + struct sockaddr_in *sin = (struct sockaddr_in*)&from; + + sin->sin_len = sizeof(*sin); + sin->sin_family = AF_INET; + sin->sin_port = th->th_sport; + sin->sin_addr = ip->ip_src; + + sin = (struct sockaddr_in*)&to2; + + sin->sin_len = sizeof(struct sockaddr_in); + sin->sin_family = AF_INET; + sin->sin_port = th->th_dport; + sin->sin_addr = ip->ip_dst; + } + } + + if (so->so_filt) { + so2 = sonewconn(so, 0, (struct sockaddr*)&from); + } else { + so2 = sonewconn(so, 0, NULL); + } + if (so2 == 0) { + tcpstat.tcps_listendrop++; + if (tcp_dropdropablreq(so)) { + if (so->so_filt) { + so2 = sonewconn(so, 0, (struct sockaddr*)&from); + } else { + so2 = sonewconn(so, 0, NULL); + } + } + if (!so2) { + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, " listen drop"); + goto drop; + } + } + + /* Point "inp" and "tp" in tandem to new socket */ + inp = (struct inpcb *)so2->so_pcb; + tp = intotcpcb(inp); + + oso = so; + socket_unlock(so, 0); /* Unlock but keep a reference on listener for now */ + + so = so2; + socket_lock(so, 1); + /* + * Mark socket as temporary until we're + * committed to keeping it. The code at + * ``drop'' and ``dropwithreset'' check the + * flag dropsocket to see if the temporary + * socket created here should be discarded. + * We mark the socket as discardable until + * we're committed to it below in TCPS_LISTEN. + * There are some error conditions in which we + * have to drop the temporary socket. + */ + dropsocket++; + /* + * Inherit INP_BOUND_IF from listener; testing if + * head_ifscope is non-NULL is sufficient, since it + * can only be set to a non-zero value earlier if + * the listener has such a flag set. + */ + if (head_ifscope != NULL) { + inp->inp_flags |= INP_BOUND_IF; + inp->inp_boundifp = head_ifscope; + } else { + inp->inp_flags &= ~INP_BOUND_IF; + } + /* + * Inherit restrictions from listener. + */ + if (head_nocell) { + inp_set_nocellular(inp); + } + if (head_noexpensive) { + inp_set_noexpensive(inp); + } + if (head_noconstrained) { + inp_set_noconstrained(inp); + } + if (head_awdl_unrestricted) { + inp_set_awdl_unrestricted(inp); + } + if (head_intcoproc_allowed) { + inp_set_intcoproc_allowed(inp); + } + /* + * Inherit {IN,IN6}_RECV_ANYIF from listener. + */ + if (head_recvanyif) { + inp->inp_flags |= INP_RECV_ANYIF; + } else { + inp->inp_flags &= ~INP_RECV_ANYIF; + } + + if (head_external_port) { + inp->inp_flags2 |= INP2_EXTERNAL_PORT; + } +#if INET6 + if (isipv6) { + inp->in6p_laddr = ip6->ip6_dst; + } else { + inp->inp_vflag &= ~INP_IPV6; + inp->inp_vflag |= INP_IPV4; +#endif /* INET6 */ + inp->inp_laddr = ip->ip_dst; +#if INET6 + } +#endif /* INET6 */ + inp->inp_lport = th->th_dport; + if (in_pcbinshash(inp, 0) != 0) { + /* + * Undo the assignments above if we failed to + * put the PCB on the hash lists. + */ +#if INET6 + if (isipv6) { + inp->in6p_laddr = in6addr_any; + } else +#endif /* INET6 */ + inp->inp_laddr.s_addr = INADDR_ANY; + inp->inp_lport = 0; + socket_lock(oso, 0); /* release ref on parent */ + socket_unlock(oso, 1); + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, " in_pcbinshash failed"); + goto drop; + } +#if INET6 + if (isipv6) { + /* + * Inherit socket options from the listening + * socket. + * Note that in6p_inputopts are not (even + * should not be) copied, since it stores + * previously received options and is used to + * detect if each new option is different than + * the previous one and hence should be passed + * to a user. + * If we copied in6p_inputopts, a user would + * not be able to receive options just after + * calling the accept system call. + */ + inp->inp_flags |= + oinp->inp_flags & INP_CONTROLOPTS; + if (oinp->in6p_outputopts) { + inp->in6p_outputopts = + ip6_copypktopts(oinp->in6p_outputopts, + M_NOWAIT); + } + } else +#endif /* INET6 */ + { + inp->inp_options = ip_srcroute(); + inp->inp_ip_tos = oinp->inp_ip_tos; + } + socket_lock(oso, 0); +#if IPSEC + /* copy old policy into new socket's */ + if (sotoinpcb(oso)->inp_sp) { + int error = 0; + /* Is it a security hole here to silently fail to copy the policy? */ + if (inp->inp_sp != NULL) { + error = ipsec_init_policy(so, &inp->inp_sp); + } + if (error != 0 || ipsec_copy_policy(sotoinpcb(oso)->inp_sp, inp->inp_sp)) { + printf("tcp_input: could not copy policy\n"); + } + } +#endif + /* inherit states from the listener */ + DTRACE_TCP4(state__change, void, NULL, struct inpcb *, inp, + struct tcpcb *, tp, int32_t, TCPS_LISTEN); + tp->t_state = TCPS_LISTEN; + tp->t_flags |= tp0->t_flags & (TF_NOPUSH | TF_NOOPT | TF_NODELAY); + tp->t_flagsext |= (tp0->t_flagsext & (TF_RXTFINDROP | TF_NOTIMEWAIT | TF_FASTOPEN)); + tp->t_keepinit = tp0->t_keepinit; + tp->t_keepcnt = tp0->t_keepcnt; + tp->t_keepintvl = tp0->t_keepintvl; + tp->t_adaptive_wtimo = tp0->t_adaptive_wtimo; + tp->t_adaptive_rtimo = tp0->t_adaptive_rtimo; + tp->t_inpcb->inp_ip_ttl = tp0->t_inpcb->inp_ip_ttl; + if ((so->so_flags & SOF_NOTSENT_LOWAT) != 0) { + tp->t_notsent_lowat = tp0->t_notsent_lowat; + } + tp->t_inpcb->inp_flags2 |= + tp0->t_inpcb->inp_flags2 & INP2_KEEPALIVE_OFFLOAD; + + /* now drop the reference on the listener */ + socket_unlock(oso, 1); + + tcp_set_max_rwinscale(tp, so, ifp); + +#if CONTENT_FILTER + if (check_cfil) { + int error = cfil_sock_attach(so2, (struct sockaddr*)&to2, (struct sockaddr*)&from, + CFS_CONNECTION_DIR_IN); + if (error != 0) { + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, " cfil_sock_attach failed"); + goto drop; + } + } +#endif /* CONTENT_FILTER */ + + KERNEL_DEBUG(DBG_FNC_TCP_NEWCONN | DBG_FUNC_END, 0, 0, 0, 0, 0); + } + } + socket_lock_assert_owned(so); + + if (net_mpklog_enabled && (m->m_pkthdr.rcvif->if_xflags & IFXF_MPK_LOG)) { + MPKL_TCP_INPUT(tcp_mpkl_log_object, + ntohs(tp->t_inpcb->inp_lport), ntohs(tp->t_inpcb->inp_fport), + th->th_seq, th->th_ack, tlen, thflags, + so->last_pid, so->so_log_seqn++); + } + + if (tp->t_state == TCPS_ESTABLISHED && tlen > 0) { + /* + * Evaluate the rate of arrival of packets to see if the + * receiver can reduce the ack traffic. The algorithm to + * stretch acks will be enabled if the connection meets + * certain criteria defined in tcp_stretch_ack_enable function. + */ + if ((tp->t_flagsext & TF_RCVUNACK_WAITSS) != 0) { + TCP_INC_VAR(tp->rcv_waitforss, nlropkts); + } + if (tcp_stretch_ack_enable(tp, thflags)) { + tp->t_flags |= TF_STRETCHACK; + tp->t_flagsext &= ~(TF_RCVUNACK_WAITSS); + tp->rcv_waitforss = 0; + } else { + tp->t_flags &= ~(TF_STRETCHACK); + } + if (TSTMP_GT(tp->rcv_unackwin - (tcp_rcvunackwin >> 1), tcp_now)) { + tp->rcv_by_unackhalfwin += (tlen + off); + tp->rcv_by_unackwin += (tlen + off); + } else { + tp->rcv_unackwin = tcp_now + tcp_rcvunackwin; + tp->rcv_by_unackwin = tp->rcv_by_unackhalfwin + tlen + off; + tp->rcv_by_unackhalfwin = tlen + off; + } } /* - * If last ACK falls within this segment's sequence numbers, - * record its timestamp. - * NOTE that the test is modified according to the latest - * proposal of the tcplw@cray.com list (Braden 1993/04/26). + * Keep track of how many bytes were received in the LRO packet */ - if ((to.to_flag & TOF_TS) != 0 && - SEQ_LEQ(th->th_seq, tp->last_ack_sent)) { - tp->ts_recent_age = tcp_now; - tp->ts_recent = to.to_tsval; + if ((pktf_sw_lro_pkt) && (nlropkts > 2)) { + tp->t_lropktlen += tlen; } - /* - * If a SYN is in the window, then this is an - * error and we send an RST and drop the connection. + * Explicit Congestion Notification - Flag that we need to send ECT if + * + The IP Congestion experienced flag was set. + * + Socket is in established state + * + We negotiated ECN in the TCP setup + * + This isn't a pure ack (tlen > 0) + * + The data is in the valid window + * + * TE_SENDECE will be cleared when we receive a packet with TH_CWR set. */ - if (thflags & TH_SYN) { - tp = tcp_drop(tp, ECONNRESET); - postevent(so, 0, EV_RESET); - goto dropwithreset; + if (ip_ecn == IPTOS_ECN_CE && tp->t_state == TCPS_ESTABLISHED && + TCP_ECN_ENABLED(tp) && tlen > 0 && + SEQ_GEQ(th->th_seq, tp->last_ack_sent) && + SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) { + tp->t_ecn_recv_ce++; + tcpstat.tcps_ecn_recv_ce++; + INP_INC_IFNET_STAT(inp, ecn_recv_ce); + /* Mark this connection as it received CE from network */ + tp->ecn_flags |= TE_RECV_ECN_CE; + tp->ecn_flags |= TE_SENDECE; } /* - * If the ACK bit is off: if in SYN-RECEIVED state or SENDSYN - * flag is on (half-synchronized state), then queue data for - * later processing; else drop segment and return. + * Clear TE_SENDECE if TH_CWR is set. This is harmless, so we don't + * bother doing extensive checks for state and whatnot. */ - if ((thflags & TH_ACK) == 0) { - if (tp->t_state == TCPS_SYN_RECEIVED || - (tp->t_flags & TF_NEEDSYN)) - goto step6; - else - goto drop; + if (thflags & TH_CWR) { + tp->ecn_flags &= ~TE_SENDECE; + tp->t_ecn_recv_cwr++; } /* - * Ack processing. + * If we received an explicit notification of congestion in + * ip tos ecn bits or by the CWR bit in TCP header flags, reset + * the ack-strteching state. We need to handle ECN notification if + * an ECN setup SYN was sent even once. */ - switch (tp->t_state) { + if (tp->t_state == TCPS_ESTABLISHED + && (tp->ecn_flags & TE_SETUPSENT) + && (ip_ecn == IPTOS_ECN_CE || (thflags & TH_CWR))) { + tcp_reset_stretch_ack(tp); + CLEAR_IAJ_STATE(tp); + } + + if (ip_ecn == IPTOS_ECN_CE && tp->t_state == TCPS_ESTABLISHED && + !TCP_ECN_ENABLED(tp) && !(tp->ecn_flags & TE_CEHEURI_SET)) { + tcpstat.tcps_ecn_fallback_ce++; + tcp_heuristic_ecn_aggressive(tp); + tp->ecn_flags |= TE_CEHEURI_SET; + } + + if (tp->t_state == TCPS_ESTABLISHED && TCP_ECN_ENABLED(tp) && + ip_ecn == IPTOS_ECN_CE && !(tp->ecn_flags & TE_CEHEURI_SET)) { + if (inp->inp_stat->rxpackets < ECN_MIN_CE_PROBES) { + tp->t_ecn_recv_ce_pkt++; + } else if (tp->t_ecn_recv_ce_pkt > ECN_MAX_CE_RATIO) { + tcpstat.tcps_ecn_fallback_ce++; + tcp_heuristic_ecn_aggressive(tp); + tp->ecn_flags |= TE_CEHEURI_SET; + INP_INC_IFNET_STAT(inp, ecn_fallback_ce); + } else { + /* We tracked the first ECN_MIN_CE_PROBES segments, we + * now know that the path is good. + */ + tp->ecn_flags |= TE_CEHEURI_SET; + } + } /* - * In SYN_RECEIVED state, the ack ACKs our SYN, so enter - * ESTABLISHED state and continue processing. - * The ACK was checked above. + * Try to determine if we are receiving a packet after a long time. + * Use our own approximation of idletime to roughly measure remote + * end's idle time. Since slowstart is used after an idle period + * we want to avoid doing LRO if the remote end is not up to date + * on initial window support and starts with 1 or 2 packets as its IW. */ - case TCPS_SYN_RECEIVED: + if (sw_lro && (tp->t_flagsext & TF_LRO_OFFLOADED) && + ((tcp_now - tp->t_rcvtime) >= (TCP_IDLETIMEOUT(tp)))) { + turnoff_lro = 1; + } - tcpstat.tcps_connects++; - soisconnected(so); - current_active_connections++; + /* Update rcvtime as a new segment was received on the connection */ + tp->t_rcvtime = tcp_now; - /* Do window scaling? */ - if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == - (TF_RCVD_SCALE|TF_REQ_SCALE)) { - tp->snd_scale = tp->requested_s_scale; - tp->rcv_scale = tp->request_r_scale; + /* + * Segment received on connection. + * Reset idle time and keep-alive timer. + */ + if (TCPS_HAVEESTABLISHED(tp->t_state)) { + tcp_keepalive_reset(tp); + + if (tp->t_mpsub) { + mptcp_reset_keepalive(tp); } - /* - * Upon successful completion of 3-way handshake, - * update cache.CC if it was undefined, pass any queued - * data to the user, and advance state appropriately. - */ - if ((taop = tcp_gettaocache(inp)) != NULL && - taop->tao_cc == 0) - taop->tao_cc = tp->cc_recv; + } - /* - * Make transitions: - * SYN-RECEIVED -> ESTABLISHED - * SYN-RECEIVED* -> FIN-WAIT-1 - */ - if (tp->t_flags & TF_NEEDFIN) { - tp->t_state = TCPS_FIN_WAIT_1; - tp->t_flags &= ~TF_NEEDFIN; - } else { - tp->t_state = TCPS_ESTABLISHED; - tp->t_timer[TCPT_KEEP] = tcp_keepidle; + /* + * Process options if not in LISTEN state, + * else do it below (after getting remote address). + */ + if (tp->t_state != TCPS_LISTEN && optp) { + tcp_dooptions(tp, optp, optlen, th, &to); + } +#if MPTCP + if (tp->t_state != TCPS_LISTEN && (so->so_flags & SOF_MP_SUBFLOW) && + mptcp_input_preproc(tp, m, th, drop_hdrlen) != 0) { + tp->t_flags |= TF_ACKNOW; + (void) tcp_output(tp); + tcp_check_timer_state(tp); + socket_unlock(so, 1); + KERNEL_DEBUG(DBG_FNC_TCP_INPUT | + DBG_FUNC_END, 0, 0, 0, 0, 0); + return; + } +#endif /* MPTCP */ + if (tp->t_state == TCPS_SYN_SENT && (thflags & TH_SYN)) { + if (!(thflags & TH_ACK) || + (SEQ_GT(th->th_ack, tp->iss) && + SEQ_LEQ(th->th_ack, tp->snd_max))) { + tcp_finalize_options(tp, &to, ifscope); } - /* - * If segment contains data or ACK, will call tcp_reass() - * later; if not, do so now to pass queued data to user. - */ - if (tilen == 0 && (thflags & TH_FIN) == 0) - (void) tcp_reass(tp, (struct tcphdr *)0, 0, - (struct mbuf *)0, isipv6); - tp->snd_wl1 = th->th_seq - 1; - /* fall into ... */ + } +#if TRAFFIC_MGT /* - * In ESTABLISHED state: drop duplicate ACKs; ACK out of range - * ACKs. If the ack is in the range - * tp->snd_una < th->th_ack <= tp->snd_max - * then advance tp->snd_una to th->th_ack and drop - * data from the retransmission queue. If this ACK reflects - * more up to date window information we update our window information. + * Compute inter-packet arrival jitter. According to RFC 3550, + * inter-packet arrival jitter is defined as the difference in + * packet spacing at the receiver compared to the sender for a + * pair of packets. When two packets of maximum segment size come + * one after the other with consecutive sequence numbers, we + * consider them as packets sent together at the sender and use + * them as a pair to compute inter-packet arrival jitter. This + * metric indicates the delay induced by the network components due + * to queuing in edge/access routers. */ - case TCPS_ESTABLISHED: - case TCPS_FIN_WAIT_1: - case TCPS_FIN_WAIT_2: - case TCPS_CLOSE_WAIT: - case TCPS_CLOSING: - case TCPS_LAST_ACK: - case TCPS_TIME_WAIT: + if (tp->t_state == TCPS_ESTABLISHED && + (thflags & (TH_SYN | TH_FIN | TH_RST | TH_URG | TH_ACK | TH_ECE | TH_PUSH)) == TH_ACK && + ((tp->t_flags & (TF_NEEDSYN | TF_NEEDFIN)) == 0) && + ((to.to_flags & TOF_TS) == 0 || + TSTMP_GEQ(to.to_tsval, tp->ts_recent)) && + th->th_seq == tp->rcv_nxt && LIST_EMPTY(&tp->t_segq)) { + int seg_size = tlen; + if (tp->iaj_pktcnt <= IAJ_IGNORE_PKTCNT) { + TCP_INC_VAR(tp->iaj_pktcnt, nlropkts); + } - if (SEQ_LEQ(th->th_ack, tp->snd_una)) { - if (tilen == 0 && tiwin == tp->snd_wnd) { - tcpstat.tcps_rcvdupack++; + if (m->m_pkthdr.pkt_flags & PKTF_SW_LRO_PKT) { + seg_size = m->m_pkthdr.lro_pktlen; + } + if (tp->iaj_size == 0 || seg_size > tp->iaj_size || + (seg_size == tp->iaj_size && tp->iaj_rcv_ts == 0)) { + /* + * State related to inter-arrival jitter is + * uninitialized or we are trying to find a good + * first packet to start computing the metric + */ + update_iaj_state(tp, seg_size, 0); + } else { + if (seg_size == tp->iaj_size) { /* - * If we have outstanding data (other than - * a window probe), this is a completely - * duplicate ack (ie, window info didn't - * change), the ack is the biggest we've - * seen and we've seen exactly our rexmt - * threshhold of them, assume a packet - * has been dropped and retransmit it. - * Kludge snd_nxt & the congestion - * window so we send only this one - * packet. - * - * We know we're losing at the current - * window size so do congestion avoidance - * (set ssthresh to half the current window - * and pull our congestion window back to - * the new ssthresh). - * - * Dup acks mean that packets have left the - * network (they're now cached at the receiver) - * so bump cwnd by the amount in the receiver - * to keep a constant cwnd packets in the - * network. + * Compute inter-arrival jitter taking + * this packet as the second packet */ - if (tp->t_timer[TCPT_REXMT] == 0 || - th->th_ack != tp->snd_una) - tp->t_dupacks = 0; - else if (++tp->t_dupacks == tcprexmtthresh) { - tcp_seq onxt = tp->snd_nxt; - u_int win = - min(tp->snd_wnd, tp->snd_cwnd) / 2 / - tp->t_maxseg; - - if (win < 2) - win = 2; - tp->snd_ssthresh = win * tp->t_maxseg; - tp->t_timer[TCPT_REXMT] = 0; - tp->t_rtt = 0; - tp->snd_nxt = th->th_ack; - tp->snd_cwnd = tp->t_maxseg; - (void) tcp_output(tp); - tp->snd_cwnd = tp->snd_ssthresh + - tp->t_maxseg * tp->t_dupacks; - if (SEQ_GT(onxt, tp->snd_nxt)) - tp->snd_nxt = onxt; - goto drop; - } else if (tp->t_dupacks > tcprexmtthresh) { - tp->snd_cwnd += tp->t_maxseg; - (void) tcp_output(tp); - goto drop; + if (pktf_sw_lro_pkt) { + compute_iaj(tp, nlropkts, + m->m_pkthdr.lro_elapsed); + } else { + compute_iaj(tp, 1, 0); } - } else - tp->t_dupacks = 0; - break; - } - /* - * If the congestion window was inflated to account - * for the other side's cached packets, retract it. - */ - if (tp->t_dupacks >= tcprexmtthresh && - tp->snd_cwnd > tp->snd_ssthresh) - tp->snd_cwnd = tp->snd_ssthresh; - tp->t_dupacks = 0; - if (SEQ_GT(th->th_ack, tp->snd_max)) { - tcpstat.tcps_rcvacktoomuch++; - goto dropafterack; + } + if (seg_size < tp->iaj_size) { + /* + * There is a smaller packet in the stream. + * Some times the maximum size supported + * on a path can change if there is a new + * link with smaller MTU. The receiver will + * not know about this change. If there + * are too many packets smaller than + * iaj_size, we try to learn the iaj_size + * again. + */ + TCP_INC_VAR(tp->iaj_small_pkt, nlropkts); + if (tp->iaj_small_pkt > RESET_IAJ_SIZE_THRESH) { + update_iaj_state(tp, seg_size, 1); + } else { + CLEAR_IAJ_STATE(tp); + } + } else { + update_iaj_state(tp, seg_size, 0); + } } + } else { + CLEAR_IAJ_STATE(tp); + } +#endif /* TRAFFIC_MGT */ + + /* + * Header prediction: check for the two common cases + * of a uni-directional data xfer. If the packet has + * no control flags, is in-sequence, the window didn't + * change and we're not retransmitting, it's a + * candidate. If the length is zero and the ack moved + * forward, we're the sender side of the xfer. Just + * free the data acked & wake any higher level process + * that was blocked waiting for space. If the length + * is non-zero and the ack didn't move, we're the + * receiver side. If we're getting packets in-order + * (the reassembly queue is empty), add the data to + * the socket buffer and note that we need a delayed ack. + * Make sure that the hidden state-flags are also off. + * Since we check for TCPS_ESTABLISHED above, it can only + * be TH_NEEDSYN. + */ + if (tp->t_state == TCPS_ESTABLISHED && + (thflags & (TH_SYN | TH_FIN | TH_RST | TH_URG | TH_ACK | TH_ECE | TH_CWR)) == TH_ACK && + ((tp->t_flags & (TF_NEEDSYN | TF_NEEDFIN)) == 0) && + ((to.to_flags & TOF_TS) == 0 || + TSTMP_GEQ(to.to_tsval, tp->ts_recent)) && + th->th_seq == tp->rcv_nxt && + tiwin && tiwin == tp->snd_wnd && + tp->snd_nxt == tp->snd_max) { /* - * If we reach this point, ACK is not a duplicate, - * i.e., it ACKs something we sent. + * If last ACK falls within this segment's sequence numbers, + * record the timestamp. + * NOTE that the test is modified according to the latest + * proposal of the tcplw@cray.com list (Braden 1993/04/26). */ - if (tp->t_flags & TF_NEEDSYN) { - /* - * T/TCP: Connection was half-synchronized, and our - * SYN has been ACK'd (so connection is now fully - * synchronized). Go to non-starred state, - * increment snd_una for ACK of SYN, and check if - * we can do window scaling. - */ - tp->t_flags &= ~TF_NEEDSYN; - tp->snd_una++; - /* Do window scaling? */ - if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == - (TF_RCVD_SCALE|TF_REQ_SCALE)) { - tp->snd_scale = tp->requested_s_scale; - tp->rcv_scale = tp->request_r_scale; - } + if ((to.to_flags & TOF_TS) != 0 && + SEQ_LEQ(th->th_seq, tp->last_ack_sent)) { + tp->ts_recent_age = tcp_now; + tp->ts_recent = to.to_tsval; } -process_ACK: - acked = th->th_ack - tp->snd_una; - tcpstat.tcps_rcvackpack++; - tcpstat.tcps_rcvackbyte += acked; + if (tlen == 0) { + if (SEQ_GT(th->th_ack, tp->snd_una) && + SEQ_LEQ(th->th_ack, tp->snd_max) && + tp->snd_cwnd >= tp->snd_ssthresh && + (!IN_FASTRECOVERY(tp) && + ((!(SACK_ENABLED(tp)) && + tp->t_dupacks < tp->t_rexmtthresh) || + (SACK_ENABLED(tp) && to.to_nsacks == 0 && + TAILQ_EMPTY(&tp->snd_holes))))) { + /* + * this is a pure ack for outstanding data. + */ + ++tcpstat.tcps_predack; - /* - * If we have a timestamp reply, update smoothed - * round trip time. If no timestamp is present but - * transmit timer is running and timed sequence - * number was acked, update smoothed round trip time. - * Since we now have an rtt measurement, cancel the - * timer backoff (cf., Phil Karn's retransmit alg.). - * Recompute the initial retransmit timer. - */ - if (to.to_flag & TOF_TS) - tcp_xmit_timer(tp, tcp_now - to.to_tsecr + 1); - else if (tp->t_rtt && SEQ_GT(th->th_ack, tp->t_rtseq)) - tcp_xmit_timer(tp,tp->t_rtt); + tcp_bad_rexmt_check(tp, th, &to); - /* - * If all outstanding data is acked, stop retransmit - * timer and remember to restart (more output or persist). - * If there is more data to be acked, restart retransmit - * timer, using current (possibly backed-off) value. - */ - if (th->th_ack == tp->snd_max) { - tp->t_timer[TCPT_REXMT] = 0; - needoutput = 1; - } else if (tp->t_timer[TCPT_PERSIST] == 0) - tp->t_timer[TCPT_REXMT] = tp->t_rxtcur; + /* Recalculate the RTT */ + tcp_compute_rtt(tp, &to, th); - /* - * If no data (only SYN) was ACK'd, - * skip rest of ACK processing. - */ - if (acked == 0) - goto step6; + VERIFY(SEQ_GEQ(th->th_ack, tp->snd_una)); + acked = BYTES_ACKED(th, tp); + tcpstat.tcps_rcvackpack++; + tcpstat.tcps_rcvackbyte += acked; - /* - * When new data is acked, open the congestion window. - * If the window gives us less than ssthresh packets - * in flight, open exponentially (maxseg per packet). - * Otherwise open linearly: maxseg per window - * (maxseg^2 / cwnd per packet). - */ - { - register u_int cw = tp->snd_cwnd; - register u_int incr = tp->t_maxseg; + /* + * Handle an ack that is in sequence during + * congestion avoidance phase. The + * calculations in this function + * assume that snd_una is not updated yet. + */ + if (CC_ALGO(tp)->congestion_avd != NULL) { + CC_ALGO(tp)->congestion_avd(tp, th); + } + tcp_ccdbg_trace(tp, th, TCP_CC_INSEQ_ACK_RCVD); + sbdrop(&so->so_snd, acked); + if (so->so_flags & SOF_ENABLE_MSGS) { + VERIFY(acked <= so->so_msg_state->msg_serial_bytes); + so->so_msg_state->msg_serial_bytes -= acked; + } + tcp_sbsnd_trim(&so->so_snd); - if (cw > tp->snd_ssthresh) - incr = incr * incr / cw; - tp->snd_cwnd = min(cw + incr, TCP_MAXWIN<snd_scale); - } - if (acked > so->so_snd.sb_cc) { - tp->snd_wnd -= so->so_snd.sb_cc; - sbdrop(&so->so_snd, (int)so->so_snd.sb_cc); - ourfinisacked = 1; - } else { - sbdrop(&so->so_snd, acked); - tp->snd_wnd -= acked; - ourfinisacked = 0; - } - need_sowwakeup++; - tp->snd_una = th->th_ack; - if (SEQ_LT(tp->snd_nxt, tp->snd_una)) - tp->snd_nxt = tp->snd_una; + if (SEQ_GT(tp->snd_una, tp->snd_recover) && + SEQ_LEQ(th->th_ack, tp->snd_recover)) { + tp->snd_recover = th->th_ack - 1; + } + tp->snd_una = th->th_ack; - switch (tp->t_state) { + TCP_RESET_REXMT_STATE(tp); - /* - * In FIN_WAIT_1 STATE in addition to the processing - * for the ESTABLISHED state if our FIN is now acknowledged - * then enter FIN_WAIT_2. - */ - case TCPS_FIN_WAIT_1: - if (ourfinisacked) { /* - * If we can't receive any more - * data, then closing user can proceed. - * Starting the timer is contrary to the - * specification, but if we don't get a FIN - * we'll hang forever. + * pull snd_wl2 up to prevent seq wrap relative + * to th_ack. */ - if (so->so_state & SS_CANTRCVMORE) { - soisdisconnected(so); - tp->t_timer[TCPT_2MSL] = tcp_maxidle; + tp->snd_wl2 = th->th_ack; + + if (tp->t_dupacks > 0) { + tp->t_dupacks = 0; + tp->t_rexmtthresh = tcprexmtthresh; } - add_to_time_wait(tp); - current_active_connections--; - tp->t_state = TCPS_FIN_WAIT_2; + + m_freem(m); + + /* + * If all outstanding data are acked, stop + * retransmit timer, otherwise restart timer + * using current (possibly backed-off) value. + * If process is waiting for space, + * wakeup/selwakeup/signal. If data + * are ready to send, let tcp_output + * decide between more output or persist. + */ + if (tp->snd_una == tp->snd_max) { + tp->t_timer[TCPT_REXMT] = 0; + tp->t_timer[TCPT_PTO] = 0; + } else if (tp->t_timer[TCPT_PERSIST] == 0) { + tp->t_timer[TCPT_REXMT] = + OFFSET_FROM_START(tp, + tp->t_rxtcur); + } + if (!SLIST_EMPTY(&tp->t_rxt_segments) && + !TCP_DSACK_SEQ_IN_WINDOW(tp, + tp->t_dsack_lastuna, tp->snd_una)) { + tcp_rxtseg_clean(tp); + } + + if ((tp->t_flagsext & TF_MEASURESNDBW) != 0 && + tp->t_bwmeas != NULL) { + tcp_bwmeas_check(tp); + } + + write_wakeup = 1; + if (!SLIST_EMPTY(&tp->t_notify_ack)) { + tcp_notify_acknowledgement(tp, so); + } + + if ((so->so_snd.sb_cc) || (tp->t_flags & TF_ACKNOW)) { + (void) tcp_output(tp); + } + + tcp_tfo_rcv_ack(tp, th); + + tcp_check_timer_state(tp); + + tcp_handle_wakeup(so, read_wakeup, write_wakeup); + + socket_unlock(so, 1); + KERNEL_DEBUG(DBG_FNC_TCP_INPUT | DBG_FUNC_END, 0, 0, 0, 0, 0); + return; } - break; + } else if (th->th_ack == tp->snd_una && + LIST_EMPTY(&tp->t_segq) && + tlen <= tcp_sbspace(tp)) { + /* + * this is a pure, in-sequence data packet + * with nothing on the reassembly queue and + * we have enough buffer space to take it. + */ + + /* + * If this is a connection in steady state, start + * coalescing packets belonging to this flow. + */ + if (turnoff_lro) { + tcp_lro_remove_state(tp->t_inpcb->inp_laddr, + tp->t_inpcb->inp_faddr, + tp->t_inpcb->inp_lport, + tp->t_inpcb->inp_fport); + tp->t_flagsext &= ~TF_LRO_OFFLOADED; + tp->t_idleat = tp->rcv_nxt; + } else if (sw_lro && !pktf_sw_lro_pkt && !isipv6 && + (so->so_flags & SOF_USELRO) && + !IFNET_IS_CELLULAR(m->m_pkthdr.rcvif) && + (m->m_pkthdr.rcvif->if_type != IFT_LOOP) && + ((th->th_seq - tp->irs) > + (tp->t_maxseg << lro_start)) && + ((tp->t_idleat == 0) || ((th->th_seq - + tp->t_idleat) > (tp->t_maxseg << lro_start)))) { + tp->t_flagsext |= TF_LRO_OFFLOADED; + tcp_start_coalescing(ip, th, tlen); + tp->t_idleat = 0; + } + + /* Clean receiver SACK report if present */ + if (SACK_ENABLED(tp) && tp->rcv_numsacks) { + tcp_clean_sackreport(tp); + } + ++tcpstat.tcps_preddat; + tp->rcv_nxt += tlen; + /* + * Pull snd_wl1 up to prevent seq wrap relative to + * th_seq. + */ + tp->snd_wl1 = th->th_seq; + /* + * Pull rcv_up up to prevent seq wrap relative to + * rcv_nxt. + */ + tp->rcv_up = tp->rcv_nxt; + TCP_INC_VAR(tcpstat.tcps_rcvpack, nlropkts); + tcpstat.tcps_rcvbyte += tlen; + if (nstat_collect) { + if (m->m_pkthdr.pkt_flags & PKTF_SW_LRO_PKT) { + INP_ADD_STAT(inp, cell, wifi, wired, + rxpackets, m->m_pkthdr.lro_npkts); + } else { + INP_ADD_STAT(inp, cell, wifi, wired, + rxpackets, 1); + } + INP_ADD_STAT(inp, cell, wifi, wired, rxbytes, + tlen); + inp_set_activity_bitmap(inp); + } + + /* + * Calculate the RTT on the receiver only if the + * connection is in streaming mode and the last + * packet was not an end-of-write + */ + if (tp->t_flags & TF_STREAMING_ON) { + tcp_compute_rtt(tp, &to, th); + } + + tcp_sbrcv_grow(tp, &so->so_rcv, &to, tlen, + TCP_AUTORCVBUF_MAX(ifp)); + + /* + * Add data to socket buffer. + */ + so_recv_data_stat(so, m, 0); + m_adj(m, drop_hdrlen); /* delayed header drop */ + + /* + * If message delivery (SOF_ENABLE_MSGS) is enabled on + * this socket, deliver the packet received as an + * in-order message with sequence number attached to it. + */ + if (isipv6) { + memcpy(&saved_hdr, ip6, sizeof(struct ip6_hdr)); + ip6 = (struct ip6_hdr *)&saved_hdr[0]; + } else { + memcpy(&saved_hdr, ip, ip->ip_hl << 2); + ip = (struct ip *)&saved_hdr[0]; + } + memcpy(&saved_tcphdr, th, sizeof(struct tcphdr)); + if (sbappendstream_rcvdemux(so, m, + th->th_seq - (tp->irs + 1), 0)) { + mptcp_handle_input(so); + read_wakeup = 1; + } + th = &saved_tcphdr; + +#if INET6 + if (isipv6) { + KERNEL_DEBUG(DBG_LAYER_END, ((th->th_dport << 16) | th->th_sport), + (((ip6->ip6_src.s6_addr16[0]) << 16) | (ip6->ip6_dst.s6_addr16[0])), + th->th_seq, th->th_ack, th->th_win); + } else +#endif + { + KERNEL_DEBUG(DBG_LAYER_END, ((th->th_dport << 16) | th->th_sport), + (((ip->ip_src.s_addr & 0xffff) << 16) | (ip->ip_dst.s_addr & 0xffff)), + th->th_seq, th->th_ack, th->th_win); + } + TCP_INC_VAR(tp->t_unacksegs, nlropkts); + if (DELAY_ACK(tp, th)) { + if ((tp->t_flags & TF_DELACK) == 0) { + tp->t_flags |= TF_DELACK; + tp->t_timer[TCPT_DELACK] = OFFSET_FROM_START(tp, tcp_delack); + } + } else { + tp->t_flags |= TF_ACKNOW; + tcp_output(tp); + } + + tcp_adaptive_rwtimo_check(tp, tlen); + + if (tlen > 0) { + tcp_tfo_rcv_data(tp); + } + + tcp_check_timer_state(tp); + + tcp_handle_wakeup(so, read_wakeup, write_wakeup); + + socket_unlock(so, 1); + KERNEL_DEBUG(DBG_FNC_TCP_INPUT | DBG_FUNC_END, 0, 0, 0, 0, 0); + return; + } + } + + /* + * Calculate amount of space in receive window, + * and then do TCP input processing. + * Receive window is amount of space in rcv queue, + * but not less than advertised window. + */ + socket_lock_assert_owned(so); + win = tcp_sbspace(tp); + if (win < 0) { + win = 0; + } else { /* clip rcv window to 4K for modems */ + if (tp->t_flags & TF_SLOWLINK && slowlink_wsize > 0) { + win = min(win, slowlink_wsize); + } + } + tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); +#if MPTCP + /* + * Ensure that the subflow receive window isn't greater + * than the connection level receive window. + */ + if ((tp->t_mpflags & TMPF_MPTCP_TRUE) && + (mp_tp = tptomptp(tp))) { + socket_lock_assert_owned(mptetoso(mp_tp->mpt_mpte)); + + if (tp->rcv_wnd > (int)(mp_tp->mpt_rcvadv - (uint32_t)mp_tp->mpt_rcvnxt)) { + tp->rcv_wnd = mp_tp->mpt_rcvadv - (uint32_t)mp_tp->mpt_rcvnxt; + tcpstat.tcps_mp_reducedwin++; + } + } +#endif /* MPTCP */ + + switch (tp->t_state) { + /* + * Initialize tp->rcv_nxt, and tp->irs, select an initial + * tp->iss, and send a segment: + * + * Also initialize tp->snd_nxt to tp->iss+1 and tp->snd_una to tp->iss. + * Fill in remote peer address fields if not previously specified. + * Enter SYN_RECEIVED state, and process any other fields of this + * segment in this state. + */ + case TCPS_LISTEN: { + struct sockaddr_in *sin; +#if INET6 + struct sockaddr_in6 *sin6; +#endif + + socket_lock_assert_owned(so); + + /* Clear the logging flags inherited from the listening socket */ + tp->t_log_flags = 0; + tp->t_flagsext &= ~TF_LOGGED_CONN_SUMMARY; + +#if INET6 + if (isipv6) { + MALLOC(sin6, struct sockaddr_in6 *, sizeof *sin6, + M_SONAME, M_NOWAIT); + if (sin6 == NULL) { + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "LISTEN malloc M_SONAME failed"); + goto drop; + } + bzero(sin6, sizeof(*sin6)); + sin6->sin6_family = AF_INET6; + sin6->sin6_len = sizeof(*sin6); + sin6->sin6_addr = ip6->ip6_src; + sin6->sin6_port = th->th_sport; + laddr6 = inp->in6p_laddr; + if (IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_laddr)) { + inp->in6p_laddr = ip6->ip6_dst; + } + if (in6_pcbconnect(inp, (struct sockaddr *)sin6, + proc0)) { + inp->in6p_laddr = laddr6; + FREE(sin6, M_SONAME); + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, " LISTEN in6_pcbconnect failed"); + goto drop; + } + FREE(sin6, M_SONAME); + } else +#endif + { + socket_lock_assert_owned(so); + MALLOC(sin, struct sockaddr_in *, sizeof *sin, M_SONAME, + M_NOWAIT); + if (sin == NULL) { + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "LISTEN malloc M_SONAME failed"); + goto drop; + } + sin->sin_family = AF_INET; + sin->sin_len = sizeof(*sin); + sin->sin_addr = ip->ip_src; + sin->sin_port = th->th_sport; + bzero((caddr_t)sin->sin_zero, sizeof(sin->sin_zero)); + laddr = inp->inp_laddr; + if (inp->inp_laddr.s_addr == INADDR_ANY) { + inp->inp_laddr = ip->ip_dst; + } + if (in_pcbconnect(inp, (struct sockaddr *)sin, proc0, + IFSCOPE_NONE, NULL)) { + inp->inp_laddr = laddr; + FREE(sin, M_SONAME); + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, " LISTEN in_pcbconnect failed"); + goto drop; + } + FREE(sin, M_SONAME); + } + + tcp_dooptions(tp, optp, optlen, th, &to); + tcp_finalize_options(tp, &to, ifscope); + + if (tfo_enabled(tp) && tcp_tfo_syn(tp, &to)) { + isconnected = TRUE; + } + + if (iss) { + tp->iss = iss; + } else { + tp->iss = tcp_new_isn(tp); + } + tp->irs = th->th_seq; + tcp_sendseqinit(tp); + tcp_rcvseqinit(tp); + tp->snd_recover = tp->snd_una; + /* + * Initialization of the tcpcb for transaction; + * set SND.WND = SEG.WND, + * initialize CCsend and CCrecv. + */ + tp->snd_wnd = tiwin; /* initial send-window */ + tp->max_sndwnd = tp->snd_wnd; + tp->t_flags |= TF_ACKNOW; + tp->t_unacksegs = 0; + DTRACE_TCP4(state__change, void, NULL, struct inpcb *, inp, + struct tcpcb *, tp, int32_t, TCPS_SYN_RECEIVED); + tp->t_state = TCPS_SYN_RECEIVED; + tp->t_timer[TCPT_KEEP] = OFFSET_FROM_START(tp, + TCP_CONN_KEEPINIT(tp)); + tp->t_connect_time = tcp_now; + dropsocket = 0; /* committed to socket */ + + if (inp->inp_flowhash == 0) { + inp->inp_flowhash = inp_calc_flowhash(inp); + } +#if INET6 + /* update flowinfo - RFC 6437 */ + if (inp->inp_flow == 0 && + inp->in6p_flags & IN6P_AUTOFLOWLABEL) { + inp->inp_flow &= ~IPV6_FLOWLABEL_MASK; + inp->inp_flow |= + (htonl(inp->inp_flowhash) & IPV6_FLOWLABEL_MASK); + } +#endif /* INET6 */ + + /* reset the incomp processing flag */ + so->so_flags &= ~(SOF_INCOMP_INPROGRESS); + tcpstat.tcps_accepts++; + if ((thflags & (TH_ECE | TH_CWR)) == (TH_ECE | TH_CWR)) { + /* ECN-setup SYN */ + tp->ecn_flags |= (TE_SETUPRECEIVED | TE_SENDIPECT); + } + + /* + * The address and connection state are finalized + */ + TCP_LOG_CONNECT(tp, false, 0); + + goto trimthenstep6; + } + + /* + * If the state is SYN_RECEIVED and the seg contains an ACK, + * but not for our SYN/ACK, send a RST. + */ + case TCPS_SYN_RECEIVED: + if ((thflags & TH_ACK) && + (SEQ_LEQ(th->th_ack, tp->snd_una) || + SEQ_GT(th->th_ack, tp->snd_max))) { + rstreason = BANDLIM_RST_OPENPORT; + IF_TCP_STATINC(ifp, ooopacket); + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "SYN_RECEIVED bad ACK"); + goto dropwithreset; + } + + /* + * In SYN_RECEIVED state, if we recv some SYNS with + * window scale and others without, window scaling should + * be disabled. Otherwise the window advertised will be + * lower if we assume scaling and the other end does not. + */ + if ((thflags & TH_SYN) && + (tp->irs == th->th_seq) && + !(to.to_flags & TOF_SCALE)) { + tp->t_flags &= ~TF_RCVD_SCALE; + } + break; + + /* + * If the state is SYN_SENT: + * if seg contains an ACK, but not for our SYN, drop the input. + * if seg contains a RST, then drop the connection. + * if seg does not contain SYN, then drop it. + * Otherwise this is an acceptable SYN segment + * initialize tp->rcv_nxt and tp->irs + * if seg contains ack then advance tp->snd_una + * if SYN has been acked change to ESTABLISHED else SYN_RCVD state + * arrange for segment to be acked (eventually) + * continue processing rest of data/controls, beginning with URG + */ + case TCPS_SYN_SENT: + if ((thflags & TH_ACK) && + (SEQ_LEQ(th->th_ack, tp->iss) || + SEQ_GT(th->th_ack, tp->snd_max))) { + rstreason = BANDLIM_UNLIMITED; + IF_TCP_STATINC(ifp, ooopacket); + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "SYN_SENT bad ACK"); + goto dropwithreset; + } + if (thflags & TH_RST) { + if ((thflags & TH_ACK) != 0) { + if (tfo_enabled(tp) && + !(tp->t_flagsext & TF_FASTOPEN_FORCE_ENABLE)) { + tcp_heuristic_tfo_rst(tp); + } + if ((tp->ecn_flags & (TE_SETUPSENT | TE_RCVD_SYN_RST)) == TE_SETUPSENT) { + /* + * On local connections, send + * non-ECN syn one time before + * dropping the connection + */ + if (tp->t_flags & TF_LOCAL) { + tp->ecn_flags |= TE_RCVD_SYN_RST; + goto drop; + } else { + tcp_heuristic_ecn_synrst(tp); + } + } + soevent(so, + (SO_FILT_HINT_LOCKED | + SO_FILT_HINT_CONNRESET)); + tp = tcp_drop(tp, ECONNREFUSED); + postevent(so, 0, EV_RESET); + } + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "SYN_SENT got RST"); + goto drop; + } + if ((thflags & TH_SYN) == 0) { + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "SYN_SENT no SYN"); + goto drop; + } + tp->snd_wnd = th->th_win; /* initial send window */ + tp->max_sndwnd = tp->snd_wnd; + + tp->irs = th->th_seq; + tcp_rcvseqinit(tp); + if (thflags & TH_ACK) { + tcpstat.tcps_connects++; + + if ((thflags & (TH_ECE | TH_CWR)) == (TH_ECE)) { + /* ECN-setup SYN-ACK */ + tp->ecn_flags |= TE_SETUPRECEIVED; + if (TCP_ECN_ENABLED(tp)) { + tcp_heuristic_ecn_success(tp); + tcpstat.tcps_ecn_client_success++; + } + } else { + if (tp->ecn_flags & TE_SETUPSENT && + tp->t_rxtshift == 0) { + tcp_heuristic_ecn_success(tp); + tcpstat.tcps_ecn_not_supported++; + } + if (tp->ecn_flags & TE_SETUPSENT && + tp->t_rxtshift > 0) { + tcp_heuristic_ecn_loss(tp); + } + + /* non-ECN-setup SYN-ACK */ + tp->ecn_flags &= ~TE_SENDIPECT; + } + +#if CONFIG_MACF_NET && CONFIG_MACF_SOCKET + /* XXXMAC: recursive lock: SOCK_LOCK(so); */ + mac_socketpeer_label_associate_mbuf(m, so); + /* XXXMAC: SOCK_UNLOCK(so); */ +#endif + /* Do window scaling on this connection? */ + if (TCP_WINDOW_SCALE_ENABLED(tp)) { + tp->snd_scale = tp->requested_s_scale; + tp->rcv_scale = tp->request_r_scale; + } + + tp->rcv_adv += min(tp->rcv_wnd, TCP_MAXWIN << tp->rcv_scale); + tp->snd_una++; /* SYN is acked */ + if (SEQ_LT(tp->snd_nxt, tp->snd_una)) { + tp->snd_nxt = tp->snd_una; + } + + /* + * We have sent more in the SYN than what is being + * acked. (e.g., TFO) + * We should restart the sending from what the receiver + * has acknowledged immediately. + */ + if (SEQ_GT(tp->snd_nxt, th->th_ack)) { + /* + * rdar://problem/33214601 + * There is a middlebox that acks all but one + * byte and still drops the data. + */ + if (!(tp->t_flagsext & TF_FASTOPEN_FORCE_ENABLE) && + (tp->t_tfo_stats & TFO_S_SYN_DATA_SENT) && + tp->snd_max == th->th_ack + 1 && + tp->snd_max > tp->snd_una + 1) { + tcp_heuristic_tfo_middlebox(tp); + + so->so_error = ENODATA; + soevent(so, + (SO_FILT_HINT_LOCKED | SO_FILT_HINT_MP_SUB_ERROR)); + + tp->t_tfo_stats |= TFO_S_ONE_BYTE_PROXY; + } + + tp->snd_max = tp->snd_nxt = th->th_ack; + } + + /* + * If there's data, delay ACK; if there's also a FIN + * ACKNOW will be turned on later. + */ + TCP_INC_VAR(tp->t_unacksegs, nlropkts); + if (DELAY_ACK(tp, th) && tlen != 0) { + if ((tp->t_flags & TF_DELACK) == 0) { + tp->t_flags |= TF_DELACK; + tp->t_timer[TCPT_DELACK] = OFFSET_FROM_START(tp, tcp_delack); + } + } else { + tp->t_flags |= TF_ACKNOW; + } + /* + * Received in SYN_SENT[*] state. + * Transitions: + * SYN_SENT --> ESTABLISHED + * SYN_SENT* --> FIN_WAIT_1 + */ + tp->t_starttime = tcp_now; + tcp_sbrcv_tstmp_check(tp); + if (tp->t_flags & TF_NEEDFIN) { + DTRACE_TCP4(state__change, void, NULL, + struct inpcb *, inp, + struct tcpcb *, tp, int32_t, + TCPS_FIN_WAIT_1); + tp->t_state = TCPS_FIN_WAIT_1; + tp->t_flags &= ~TF_NEEDFIN; + thflags &= ~TH_SYN; + + TCP_LOG_CONNECTION_SUMMARY(tp); + } else { + DTRACE_TCP4(state__change, void, NULL, + struct inpcb *, inp, struct tcpcb *, + tp, int32_t, TCPS_ESTABLISHED); + tp->t_state = TCPS_ESTABLISHED; + tp->t_timer[TCPT_KEEP] = + OFFSET_FROM_START(tp, + TCP_CONN_KEEPIDLE(tp)); + if (nstat_collect) { + nstat_route_connect_success( + inp->inp_route.ro_rt); + } + /* + * The SYN is acknowledged but una is not + * updated yet. So pass the value of + * ack to compute sndbytes correctly + */ + inp_count_sndbytes(inp, th->th_ack); + } +#if MPTCP + /* + * Do not send the connect notification for additional + * subflows until ACK for 3-way handshake arrives. + */ + if ((!(tp->t_mpflags & TMPF_MPTCP_TRUE)) && + (tp->t_mpflags & TMPF_SENT_JOIN)) { + isconnected = FALSE; + } else +#endif /* MPTCP */ + isconnected = TRUE; + + if ((tp->t_tfo_flags & (TFO_F_COOKIE_REQ | TFO_F_COOKIE_SENT)) || + (tp->t_tfo_stats & TFO_S_SYN_DATA_SENT)) { + tcp_tfo_synack(tp, &to); + + if ((tp->t_tfo_stats & TFO_S_SYN_DATA_SENT) && + SEQ_LT(tp->snd_una, th->th_ack)) { + tp->t_tfo_stats |= TFO_S_SYN_DATA_ACKED; + tcpstat.tcps_tfo_syn_data_acked++; +#if MPTCP + if (so->so_flags & SOF_MP_SUBFLOW) { + so->so_flags1 |= SOF1_TFO_REWIND; + } +#endif + tcp_tfo_rcv_probe(tp, tlen); + } + } + } else { + /* + * Received initial SYN in SYN-SENT[*] state => simul- + * taneous open. If segment contains CC option and there is + * a cached CC, apply TAO test; if it succeeds, connection is + * half-synchronized. Otherwise, do 3-way handshake: + * SYN-SENT -> SYN-RECEIVED + * SYN-SENT* -> SYN-RECEIVED* + */ + tp->t_flags |= TF_ACKNOW; + tp->t_timer[TCPT_REXMT] = 0; + DTRACE_TCP4(state__change, void, NULL, struct inpcb *, inp, + struct tcpcb *, tp, int32_t, TCPS_SYN_RECEIVED); + tp->t_state = TCPS_SYN_RECEIVED; + + /* + * During simultaneous open, TFO should not be used. + * So, we disable it here, to prevent that data gets + * sent on the SYN/ACK. + */ + tcp_disable_tfo(tp); + } + +trimthenstep6: + /* + * Advance th->th_seq to correspond to first data byte. + * If data, trim to stay within window, + * dropping FIN if necessary. + */ + th->th_seq++; + if (tlen > tp->rcv_wnd) { + todrop = tlen - tp->rcv_wnd; + m_adj(m, -todrop); + tlen = tp->rcv_wnd; + thflags &= ~TH_FIN; + tcpstat.tcps_rcvpackafterwin++; + tcpstat.tcps_rcvbyteafterwin += todrop; + } + tp->snd_wl1 = th->th_seq - 1; + tp->rcv_up = th->th_seq; + /* + * Client side of transaction: already sent SYN and data. + * If the remote host used T/TCP to validate the SYN, + * our data will be ACK'd; if so, enter normal data segment + * processing in the middle of step 5, ack processing. + * Otherwise, goto step 6. + */ + if (thflags & TH_ACK) { + goto process_ACK; + } + goto step6; + /* + * If the state is LAST_ACK or CLOSING or TIME_WAIT: + * do normal processing. + * + * NB: Leftover from RFC1644 T/TCP. Cases to be reused later. + */ + case TCPS_LAST_ACK: + case TCPS_CLOSING: + case TCPS_TIME_WAIT: + break; /* continue normal processing */ + + /* Received a SYN while connection is already established. + * This is a "half open connection and other anomalies" described + * in RFC793 page 34, send an ACK so the remote reset the connection + * or recovers by adjusting its sequence numbering. Sending an ACK is + * in accordance with RFC 5961 Section 4.2 + */ + case TCPS_ESTABLISHED: + if (thflags & TH_SYN) { + /* Drop the packet silently if we have reached the limit */ + if (tcp_do_rfc5961 && tcp_is_ack_ratelimited(tp)) { + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "ESTABLISHED rfc5961 rate limited"); + goto drop; + } else { + /* Send challenge ACK */ + tcpstat.tcps_synchallenge++; + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "ESTABLISHED rfc5961 challenge ACK"); + goto dropafterack; + } + } + break; + } + + /* + * States other than LISTEN or SYN_SENT. + * First check the RST flag and sequence number since reset segments + * are exempt from the timestamp and connection count tests. This + * fixes a bug introduced by the Stevens, vol. 2, p. 960 bugfix + * below which allowed reset segments in half the sequence space + * to fall though and be processed (which gives forged reset + * segments with a random sequence number a 50 percent chance of + * killing a connection). + * Then check timestamp, if present. + * Then check the connection count, if present. + * Then check that at least some bytes of segment are within + * receive window. If segment begins before rcv_nxt, + * drop leading data (and SYN); if nothing left, just ack. + * + * + * If the RST bit is set, check the sequence number to see + * if this is a valid reset segment. + * RFC 793 page 37: + * In all states except SYN-SENT, all reset (RST) segments + * are validated by checking their SEQ-fields. A reset is + * valid if its sequence number is in the window. + * Note: this does not take into account delayed ACKs, so + * we should test against last_ack_sent instead of rcv_nxt. + * The sequence number in the reset segment is normally an + * echo of our outgoing acknowlegement numbers, but some hosts + * send a reset with the sequence number at the rightmost edge + * of our receive window, and we have to handle this case. + * Note 2: Paul Watson's paper "Slipping in the Window" has shown + * that brute force RST attacks are possible. To combat this, + * we use a much stricter check while in the ESTABLISHED state, + * only accepting RSTs where the sequence number is equal to + * last_ack_sent. In all other states (the states in which a + * RST is more likely), the more permissive check is used. + * RFC 5961 Section 3.2: if the RST bit is set, sequence # is + * within the receive window and last_ack_sent == seq, + * then reset the connection. Otherwise if the seq doesn't + * match last_ack_sent, TCP must send challenge ACK. Perform + * rate limitation when sending the challenge ACK. + * If we have multiple segments in flight, the intial reset + * segment sequence numbers will be to the left of last_ack_sent, + * but they will eventually catch up. + * In any case, it never made sense to trim reset segments to + * fit the receive window since RFC 1122 says: + * 4.2.2.12 RST Segment: RFC-793 Section 3.4 + * + * A TCP SHOULD allow a received RST segment to include data. + * + * DISCUSSION + * It has been suggested that a RST segment could contain + * ASCII text that encoded and explained the cause of the + * RST. No standard has yet been established for such + * data. + * + * If the reset segment passes the sequence number test examine + * the state: + * SYN_RECEIVED STATE: + * If passive open, return to LISTEN state. + * If active open, inform user that connection was refused. + * ESTABLISHED, FIN_WAIT_1, FIN_WAIT_2, CLOSE_WAIT STATES: + * Inform user that connection was reset, and close tcb. + * CLOSING, LAST_ACK STATES: + * Close the tcb. + * TIME_WAIT STATE: + * Drop the segment - see Stevens, vol. 2, p. 964 and + * RFC 1337. + * + * Radar 4803931: Allows for the case where we ACKed the FIN but + * there is already a RST in flight from the peer. + * In that case, accept the RST for non-established + * state if it's one off from last_ack_sent. + * + */ + if (thflags & TH_RST) { + if ((SEQ_GEQ(th->th_seq, tp->last_ack_sent) && + SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) || + (tp->rcv_wnd == 0 && + ((tp->last_ack_sent == th->th_seq) || + ((tp->last_ack_sent - 1) == th->th_seq)))) { + if (tcp_do_rfc5961 == 0 || tp->last_ack_sent == th->th_seq) { + switch (tp->t_state) { + case TCPS_SYN_RECEIVED: + IF_TCP_STATINC(ifp, rstinsynrcv); + so->so_error = ECONNREFUSED; + goto close; + + case TCPS_ESTABLISHED: + if (tcp_do_rfc5961 == 0 && tp->last_ack_sent != th->th_seq) { + tcpstat.tcps_badrst++; + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "ESTABLISHED rfc5961 bad RST"); + goto drop; + } + if (TCP_ECN_ENABLED(tp) && + tp->snd_una == tp->iss + 1 && + SEQ_GT(tp->snd_max, tp->snd_una)) { + /* + * If the first data packet on an + * ECN connection, receives a RST + * increment the heuristic + */ + tcp_heuristic_ecn_droprst(tp); + } + case TCPS_FIN_WAIT_1: + case TCPS_CLOSE_WAIT: + /* + * Drop through ... + */ + case TCPS_FIN_WAIT_2: + so->so_error = ECONNRESET; +close: + postevent(so, 0, EV_RESET); + soevent(so, + (SO_FILT_HINT_LOCKED | + SO_FILT_HINT_CONNRESET)); + + tcpstat.tcps_drops++; + tp = tcp_close(tp); + break; + + case TCPS_CLOSING: + case TCPS_LAST_ACK: + tp = tcp_close(tp); + break; + + case TCPS_TIME_WAIT: + break; + } + } else if (tcp_do_rfc5961) { + tcpstat.tcps_badrst++; + /* Drop if we have reached the ACK limit */ + if (tcp_is_ack_ratelimited(tp)) { + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "ESTABLISHED rfc5961 rate limited"); + goto drop; + } else { + /* Send challenge ACK */ + tcpstat.tcps_rstchallenge++; + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "ESTABLISHED rfc5961 challenge ACK"); + goto dropafterack; + } + } + } + goto drop; + } + + /* + * RFC 1323 PAWS: If we have a timestamp reply on this segment + * and it's less than ts_recent, drop it. + */ + if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent && + TSTMP_LT(to.to_tsval, tp->ts_recent)) { + /* Check to see if ts_recent is over 24 days old. */ + if ((int)(tcp_now - tp->ts_recent_age) > TCP_PAWS_IDLE) { + /* + * Invalidate ts_recent. If this segment updates + * ts_recent, the age will be reset later and ts_recent + * will get a valid value. If it does not, setting + * ts_recent to zero will at least satisfy the + * requirement that zero be placed in the timestamp + * echo reply when ts_recent isn't valid. The + * age isn't reset until we get a valid ts_recent + * because we don't want out-of-order segments to be + * dropped when ts_recent is old. + */ + tp->ts_recent = 0; + } else { + tcpstat.tcps_rcvduppack++; + tcpstat.tcps_rcvdupbyte += tlen; + tp->t_pawsdrop++; + tcpstat.tcps_pawsdrop++; + + /* + * PAWS-drop when ECN is being used? That indicates + * that ECT-marked packets take a different path, with + * different congestion-characteristics. + * + * Only fallback when we did send less than 2GB as PAWS + * really has no reason to kick in earlier. + */ + if (TCP_ECN_ENABLED(tp) && + inp->inp_stat->rxbytes < 2147483648) { + INP_INC_IFNET_STAT(inp, ecn_fallback_reorder); + tcpstat.tcps_ecn_fallback_reorder++; + tcp_heuristic_ecn_aggressive(tp); + } + + if (nstat_collect) { + nstat_route_rx(tp->t_inpcb->inp_route.ro_rt, + 1, tlen, NSTAT_RX_FLAG_DUPLICATE); + INP_ADD_STAT(inp, cell, wifi, wired, + rxpackets, 1); + INP_ADD_STAT(inp, cell, wifi, wired, + rxbytes, tlen); + tp->t_stat.rxduplicatebytes += tlen; + inp_set_activity_bitmap(inp); + } + if (tlen > 0) { + goto dropafterack; + } + goto drop; + } + } + + /* + * In the SYN-RECEIVED state, validate that the packet belongs to + * this connection before trimming the data to fit the receive + * window. Check the sequence number versus IRS since we know + * the sequence numbers haven't wrapped. This is a partial fix + * for the "LAND" DoS attack. + */ + if (tp->t_state == TCPS_SYN_RECEIVED && SEQ_LT(th->th_seq, tp->irs)) { + rstreason = BANDLIM_RST_OPENPORT; + IF_TCP_STATINC(ifp, dospacket); + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "SYN_RECEIVED bad SEQ"); + goto dropwithreset; + } + + /* + * Check if there is old data at the beginning of the window + * i.e. the sequence number is before rcv_nxt + */ + todrop = tp->rcv_nxt - th->th_seq; + if (todrop > 0) { + boolean_t is_syn_set = FALSE; + + if (thflags & TH_SYN) { + is_syn_set = TRUE; + thflags &= ~TH_SYN; + th->th_seq++; + if (th->th_urp > 1) { + th->th_urp--; + } else { + thflags &= ~TH_URG; + } + todrop--; + } + /* + * Following if statement from Stevens, vol. 2, p. 960. + * The amount of duplicate data is greater than or equal + * to the size of the segment - entire segment is duplicate + */ + if (todrop > tlen + || (todrop == tlen && (thflags & TH_FIN) == 0)) { + /* + * Any valid FIN must be to the left of the window. + * At this point the FIN must be a duplicate or out + * of sequence; drop it. + */ + thflags &= ~TH_FIN; + + /* + * Send an ACK to resynchronize and drop any data. + * But keep on processing for RST or ACK. + * + * If the SYN bit was originally set, then only send + * an ACK if we are not rate-limiting this connection. + */ + if (tcp_do_rfc5961 && is_syn_set) { + if (!tcp_is_ack_ratelimited(tp)) { + tcpstat.tcps_synchallenge++; + tp->t_flags |= TF_ACKNOW; + } + } else { + tp->t_flags |= TF_ACKNOW; + } + + if (todrop == 1) { + /* This could be a keepalive */ + soevent(so, SO_FILT_HINT_LOCKED | + SO_FILT_HINT_KEEPALIVE); + } + todrop = tlen; + tcpstat.tcps_rcvduppack++; + tcpstat.tcps_rcvdupbyte += todrop; + } else { + tcpstat.tcps_rcvpartduppack++; + tcpstat.tcps_rcvpartdupbyte += todrop; + } + + if (TCP_DSACK_ENABLED(tp) && todrop > 1) { + /* + * Note the duplicate data sequence space so that + * it can be reported in DSACK option. + */ + tp->t_dsack_lseq = th->th_seq; + tp->t_dsack_rseq = th->th_seq + todrop; + tp->t_flags |= TF_ACKNOW; + } + if (nstat_collect) { + nstat_route_rx(tp->t_inpcb->inp_route.ro_rt, 1, + todrop, NSTAT_RX_FLAG_DUPLICATE); + INP_ADD_STAT(inp, cell, wifi, wired, rxpackets, 1); + INP_ADD_STAT(inp, cell, wifi, wired, rxbytes, todrop); + tp->t_stat.rxduplicatebytes += todrop; + inp_set_activity_bitmap(inp); + } + drop_hdrlen += todrop; /* drop from the top afterwards */ + th->th_seq += todrop; + tlen -= todrop; + if (th->th_urp > todrop) { + th->th_urp -= todrop; + } else { + thflags &= ~TH_URG; + th->th_urp = 0; + } + } + + /* + * If new data are received on a connection after the user + * processes are gone, then RST the other end. + * Send also a RST when we received a data segment after we've + * sent our FIN when the socket is defunct. + * Note that an MPTCP subflow socket would have SS_NOFDREF set + * by default. So, if it's an MPTCP-subflow we rather check the + * MPTCP-level's socket state for SS_NOFDREF. + */ + if (tlen) { + boolean_t close_it = FALSE; + + if (!(so->so_flags & SOF_MP_SUBFLOW) && (so->so_state & SS_NOFDREF) && + tp->t_state > TCPS_CLOSE_WAIT) { + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "SS_NOFDREF"); + close_it = TRUE; + } + + if ((so->so_flags & SOF_MP_SUBFLOW) && (mptetoso(tptomptp(tp)->mpt_mpte)->so_state & SS_NOFDREF) && + tp->t_state > TCPS_CLOSE_WAIT) { + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "SOF_MP_SUBFLOW SS_NOFDREF"); + close_it = TRUE; + } + + if ((so->so_flags & SOF_DEFUNCT) && tp->t_state > TCPS_FIN_WAIT_1) { + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "SOF_DEFUNCT"); + close_it = TRUE; + } + + if (close_it) { + tp = tcp_close(tp); + tcpstat.tcps_rcvafterclose++; + rstreason = BANDLIM_UNLIMITED; + IF_TCP_STATINC(ifp, cleanup); + goto dropwithreset; + } + } + + /* + * If segment ends after window, drop trailing data + * (and PUSH and FIN); if nothing left, just ACK. + */ + todrop = (th->th_seq + tlen) - (tp->rcv_nxt + tp->rcv_wnd); + if (todrop > 0) { + tcpstat.tcps_rcvpackafterwin++; + if (todrop >= tlen) { + tcpstat.tcps_rcvbyteafterwin += tlen; + /* + * If a new connection request is received + * while in TIME_WAIT, drop the old connection + * and start over if the sequence numbers + * are above the previous ones. + */ + if (thflags & TH_SYN && + tp->t_state == TCPS_TIME_WAIT && + SEQ_GT(th->th_seq, tp->rcv_nxt)) { + iss = tcp_new_isn(tp); + tp = tcp_close(tp); + socket_unlock(so, 1); + goto findpcb; + } + /* + * If window is closed can only take segments at + * window edge, and have to drop data and PUSH from + * incoming segments. Continue processing, but + * remember to ack. Otherwise, drop segment + * and ack. + */ + if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { + tp->t_flags |= TF_ACKNOW; + tcpstat.tcps_rcvwinprobe++; + } else { + goto dropafterack; + } + } else { + tcpstat.tcps_rcvbyteafterwin += todrop; + } + m_adj(m, -todrop); + tlen -= todrop; + thflags &= ~(TH_PUSH | TH_FIN); + } + + /* + * If last ACK falls within this segment's sequence numbers, + * record its timestamp. + * NOTE: + * 1) That the test incorporates suggestions from the latest + * proposal of the tcplw@cray.com list (Braden 1993/04/26). + * 2) That updating only on newer timestamps interferes with + * our earlier PAWS tests, so this check should be solely + * predicated on the sequence space of this segment. + * 3) That we modify the segment boundary check to be + * Last.ACK.Sent <= SEG.SEQ + SEG.Len + * instead of RFC1323's + * Last.ACK.Sent < SEG.SEQ + SEG.Len, + * This modified check allows us to overcome RFC1323's + * limitations as described in Stevens TCP/IP Illustrated + * Vol. 2 p.869. In such cases, we can still calculate the + * RTT correctly when RCV.NXT == Last.ACK.Sent. + */ + if ((to.to_flags & TOF_TS) != 0 && + SEQ_LEQ(th->th_seq, tp->last_ack_sent) && + SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen + + ((thflags & (TH_SYN | TH_FIN)) != 0))) { + tp->ts_recent_age = tcp_now; + tp->ts_recent = to.to_tsval; + } + + /* + * Stevens: If a SYN is in the window, then this is an + * error and we send an RST and drop the connection. + * + * RFC 5961 Section 4.2 + * Send challenge ACK for any SYN in synchronized state + * Perform rate limitation in doing so. + */ + if (thflags & TH_SYN) { + if (tcp_do_rfc5961) { + tcpstat.tcps_badsyn++; + /* Drop if we have reached ACK limit */ + if (tcp_is_ack_ratelimited(tp)) { + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "rfc5961 bad SYN rate limited"); + goto drop; + } else { + /* Send challenge ACK */ + tcpstat.tcps_synchallenge++; + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "rfc5961 bad SYN challenge ack"); + goto dropafterack; + } + } else { + tp = tcp_drop(tp, ECONNRESET); + rstreason = BANDLIM_UNLIMITED; + postevent(so, 0, EV_RESET); + IF_TCP_STATINC(ifp, synwindow); + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "bad SYN"); + goto dropwithreset; + } + } + + /* + * If the ACK bit is off: if in SYN-RECEIVED state or SENDSYN + * flag is on (half-synchronized state), then queue data for + * later processing; else drop segment and return. + */ + if ((thflags & TH_ACK) == 0) { + if (tp->t_state == TCPS_SYN_RECEIVED || + (tp->t_flags & TF_NEEDSYN)) { + if ((tfo_enabled(tp))) { + /* + * So, we received a valid segment while in + * SYN-RECEIVED (TF_NEEDSYN is actually never + * set, so this is dead code). + * As this cannot be an RST (see that if a bit + * higher), and it does not have the ACK-flag + * set, we want to retransmit the SYN/ACK. + * Thus, we have to reset snd_nxt to snd_una to + * trigger the going back to sending of the + * SYN/ACK. This is more consistent with the + * behavior of tcp_output(), which expects + * to send the segment that is pointed to by + * snd_nxt. + */ + tp->snd_nxt = tp->snd_una; + + /* + * We need to make absolutely sure that we are + * going to reply upon a duplicate SYN-segment. + */ + if (th->th_flags & TH_SYN) { + needoutput = 1; + } + } + + goto step6; + } else if (tp->t_flags & TF_ACKNOW) { + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "bad ACK"); + goto dropafterack; + } else { + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "bad ACK"); + goto drop; + } + } + + /* + * Ack processing. + */ + + switch (tp->t_state) { + /* + * In SYN_RECEIVED state, the ack ACKs our SYN, so enter + * ESTABLISHED state and continue processing. + * The ACK was checked above. + */ + case TCPS_SYN_RECEIVED: + + tcpstat.tcps_connects++; + + /* Do window scaling? */ + if (TCP_WINDOW_SCALE_ENABLED(tp)) { + tp->snd_scale = tp->requested_s_scale; + tp->rcv_scale = tp->request_r_scale; + tp->snd_wnd = th->th_win << tp->snd_scale; + tp->max_sndwnd = tp->snd_wnd; + tiwin = tp->snd_wnd; + } + /* + * Make transitions: + * SYN-RECEIVED -> ESTABLISHED + * SYN-RECEIVED* -> FIN-WAIT-1 + */ + tp->t_starttime = tcp_now; + tcp_sbrcv_tstmp_check(tp); + if (tp->t_flags & TF_NEEDFIN) { + DTRACE_TCP4(state__change, void, NULL, + struct inpcb *, inp, + struct tcpcb *, tp, int32_t, TCPS_FIN_WAIT_1); + tp->t_state = TCPS_FIN_WAIT_1; + tp->t_flags &= ~TF_NEEDFIN; + + TCP_LOG_CONNECTION_SUMMARY(tp); + } else { + DTRACE_TCP4(state__change, void, NULL, + struct inpcb *, inp, + struct tcpcb *, tp, int32_t, TCPS_ESTABLISHED); + tp->t_state = TCPS_ESTABLISHED; + tp->t_timer[TCPT_KEEP] = OFFSET_FROM_START(tp, + TCP_CONN_KEEPIDLE(tp)); + if (nstat_collect) { + nstat_route_connect_success( + tp->t_inpcb->inp_route.ro_rt); + } + /* + * The SYN is acknowledged but una is not updated + * yet. So pass the value of ack to compute + * sndbytes correctly + */ + inp_count_sndbytes(inp, th->th_ack); + } + /* + * If segment contains data or ACK, will call tcp_reass() + * later; if not, do so now to pass queued data to user. + */ + if (tlen == 0 && (thflags & TH_FIN) == 0) { + if (isipv6) { + memcpy(&saved_hdr, ip6, sizeof(struct ip6_hdr)); + ip6 = (struct ip6_hdr *)&saved_hdr[0]; + } else { + memcpy(&saved_hdr, ip, ip->ip_hl << 2); + ip = (struct ip *)&saved_hdr[0]; + } + memcpy(&saved_tcphdr, th, sizeof(struct tcphdr)); + (void) tcp_reass(tp, (struct tcphdr *)0, &tlen, + NULL, ifp, &read_wakeup); + th = &saved_tcphdr; + } + tp->snd_wl1 = th->th_seq - 1; + +#if MPTCP + /* + * Do not send the connect notification for additional subflows + * until ACK for 3-way handshake arrives. + */ + if ((!(tp->t_mpflags & TMPF_MPTCP_TRUE)) && + (tp->t_mpflags & TMPF_SENT_JOIN)) { + isconnected = FALSE; + } else +#endif /* MPTCP */ + isconnected = TRUE; + if ((tp->t_tfo_flags & TFO_F_COOKIE_VALID)) { + /* Done this when receiving the SYN */ + isconnected = FALSE; + + OSDecrementAtomic(&tcp_tfo_halfcnt); + + /* Panic if something has gone terribly wrong. */ + VERIFY(tcp_tfo_halfcnt >= 0); + + tp->t_tfo_flags &= ~TFO_F_COOKIE_VALID; + } + + /* + * In case there is data in the send-queue (e.g., TFO is being + * used, or connectx+data has been done), then if we would + * "FALLTHROUGH", we would handle this ACK as if data has been + * acknowledged. But, we have to prevent this. And this + * can be prevented by increasing snd_una by 1, so that the + * SYN is not considered as data (snd_una++ is actually also + * done in SYN_SENT-state as part of the regular TCP stack). + * + * In case there is data on this ack as well, the data will be + * handled by the label "dodata" right after step6. + */ + if (so->so_snd.sb_cc) { + tp->snd_una++; /* SYN is acked */ + if (SEQ_LT(tp->snd_nxt, tp->snd_una)) { + tp->snd_nxt = tp->snd_una; + } + + /* + * No duplicate-ACK handling is needed. So, we + * directly advance to processing the ACK (aka, + * updating the RTT estimation,...) + * + * But, we first need to handle eventual SACKs, + * because TFO will start sending data with the + * SYN/ACK, so it might be that the client + * includes a SACK with its ACK. + */ + if (SACK_ENABLED(tp) && + (to.to_nsacks > 0 || + !TAILQ_EMPTY(&tp->snd_holes))) { + tcp_sack_doack(tp, &to, th, + &sack_bytes_acked); + } + + goto process_ACK; + } + + /* FALLTHROUGH */ + + /* + * In ESTABLISHED state: drop duplicate ACKs; ACK out of range + * ACKs. If the ack is in the range + * tp->snd_una < th->th_ack <= tp->snd_max + * then advance tp->snd_una to th->th_ack and drop + * data from the retransmission queue. If this ACK reflects + * more up to date window information we update our window information. + */ + case TCPS_ESTABLISHED: + case TCPS_FIN_WAIT_1: + case TCPS_FIN_WAIT_2: + case TCPS_CLOSE_WAIT: + case TCPS_CLOSING: + case TCPS_LAST_ACK: + case TCPS_TIME_WAIT: + if (SEQ_GT(th->th_ack, tp->snd_max)) { + tcpstat.tcps_rcvacktoomuch++; + if (tcp_do_rfc5961 && tcp_is_ack_ratelimited(tp)) { + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "rfc5961 rcvacktoomuch"); + goto drop; + } else { + goto dropafterack; + } + } + if (tcp_do_rfc5961 && SEQ_LT(th->th_ack, tp->snd_una - tp->max_sndwnd)) { + if (tcp_is_ack_ratelimited(tp)) { + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "rfc5961 bad ACK"); + goto drop; + } else { + goto dropafterack; + } + } + if (SACK_ENABLED(tp) && to.to_nsacks > 0) { + recvd_dsack = tcp_sack_process_dsack(tp, &to, th); + /* + * If DSACK is received and this packet has no + * other SACK information, it can be dropped. + * We do not want to treat it as a duplicate ack. + */ + if (recvd_dsack && + SEQ_LEQ(th->th_ack, tp->snd_una) && + to.to_nsacks == 0) { + tcp_bad_rexmt_check(tp, th, &to); + goto drop; + } + } + + if (SACK_ENABLED(tp) && + (to.to_nsacks > 0 || !TAILQ_EMPTY(&tp->snd_holes))) { + tcp_sack_doack(tp, &to, th, &sack_bytes_acked); + } + +#if MPTCP + if (tp->t_mpuna && SEQ_GEQ(th->th_ack, tp->t_mpuna)) { + if (tp->t_mpflags & TMPF_PREESTABLISHED) { + /* MP TCP establishment succeeded */ + tp->t_mpuna = 0; + if (tp->t_mpflags & TMPF_JOINED_FLOW) { + if (tp->t_mpflags & TMPF_SENT_JOIN) { + tp->t_mpflags &= + ~TMPF_PREESTABLISHED; + tp->t_mpflags |= + TMPF_MPTCP_TRUE; + + tp->t_timer[TCPT_JACK_RXMT] = 0; + tp->t_mprxtshift = 0; + isconnected = TRUE; + } else { + isconnected = FALSE; + } + } else { + isconnected = TRUE; + } + } + } +#endif /* MPTCP */ + + tcp_tfo_rcv_ack(tp, th); + + /* + * If we have outstanding data (other than + * a window probe), this is a completely + * duplicate ack and the ack is the biggest we've seen. + * + * Need to accommodate a change in window on duplicate acks + * to allow operating systems that update window during + * recovery with SACK + */ + if (SEQ_LEQ(th->th_ack, tp->snd_una)) { + if (tlen == 0 && (tiwin == tp->snd_wnd || + (to.to_nsacks > 0 && sack_bytes_acked > 0))) { + /* + * If both ends send FIN at the same time, + * then the ack will be a duplicate ack + * but we have to process the FIN. Check + * for this condition and process the FIN + * instead of the dupack + */ + if ((thflags & TH_FIN) && + !TCPS_HAVERCVDFIN(tp->t_state)) { + break; + } +process_dupack: +#if MPTCP + /* + * MPTCP options that are ignored must + * not be treated as duplicate ACKs. + */ + if (to.to_flags & TOF_MPTCP) { + goto drop; + } + + if ((isconnected) && (tp->t_mpflags & TMPF_JOINED_FLOW)) { + mptcplog((LOG_DEBUG, "MPTCP " + "Sockets: bypass ack recovery\n"), + MPTCP_SOCKET_DBG, + MPTCP_LOGLVL_VERBOSE); + break; + } +#endif /* MPTCP */ + /* + * If a duplicate acknowledgement was seen + * after ECN, it indicates packet loss in + * addition to ECN. Reset INRECOVERY flag + * so that we can process partial acks + * correctly + */ + if (tp->ecn_flags & TE_INRECOVERY) { + tp->ecn_flags &= ~TE_INRECOVERY; + } + + tcpstat.tcps_rcvdupack++; + ++tp->t_dupacks; + + /* + * Check if we need to reset the limit on + * early retransmit + */ + if (tp->t_early_rexmt_count > 0 && + TSTMP_GEQ(tcp_now, + (tp->t_early_rexmt_win + + TCP_EARLY_REXMT_WIN))) { + tp->t_early_rexmt_count = 0; + } + + /* + * Is early retransmit needed? We check for + * this when the connection is waiting for + * duplicate acks to enter fast recovery. + */ + if (!IN_FASTRECOVERY(tp)) { + tcp_early_rexmt_check(tp, th); + } + + /* + * If we've seen exactly rexmt threshold + * of duplicate acks, assume a packet + * has been dropped and retransmit it. + * Kludge snd_nxt & the congestion + * window so we send only this one + * packet. + * + * We know we're losing at the current + * window size so do congestion avoidance + * (set ssthresh to half the current window + * and pull our congestion window back to + * the new ssthresh). + * + * Dup acks mean that packets have left the + * network (they're now cached at the receiver) + * so bump cwnd by the amount in the receiver + * to keep a constant cwnd packets in the + * network. + */ + if (tp->t_timer[TCPT_REXMT] == 0 || + (th->th_ack != tp->snd_una + && sack_bytes_acked == 0)) { + tp->t_dupacks = 0; + tp->t_rexmtthresh = tcprexmtthresh; + } else if (tp->t_dupacks > tp->t_rexmtthresh || + IN_FASTRECOVERY(tp)) { + /* + * If this connection was seeing packet + * reordering, then recovery might be + * delayed to disambiguate between + * reordering and loss + */ + if (SACK_ENABLED(tp) && !IN_FASTRECOVERY(tp) && + (tp->t_flagsext & + (TF_PKTS_REORDERED | TF_DELAY_RECOVERY)) == + (TF_PKTS_REORDERED | TF_DELAY_RECOVERY)) { + /* + * Since the SACK information is already + * updated, this ACK will be dropped + */ + break; + } + + if (SACK_ENABLED(tp) + && IN_FASTRECOVERY(tp)) { + int awnd; + + /* + * Compute the amount of data in flight first. + * We can inject new data into the pipe iff + * we have less than 1/2 the original window's + * worth of data in flight. + */ + awnd = (tp->snd_nxt - tp->snd_fack) + + tp->sackhint.sack_bytes_rexmit; + if (awnd < tp->snd_ssthresh) { + tp->snd_cwnd += tp->t_maxseg; + if (tp->snd_cwnd > tp->snd_ssthresh) { + tp->snd_cwnd = tp->snd_ssthresh; + } + } + } else { + tp->snd_cwnd += tp->t_maxseg; + } + + /* Process any window updates */ + if (tiwin > tp->snd_wnd) { + tcp_update_window(tp, thflags, + th, tiwin, tlen); + } + tcp_ccdbg_trace(tp, th, + TCP_CC_IN_FASTRECOVERY); + + (void) tcp_output(tp); + + goto drop; + } else if (tp->t_dupacks == tp->t_rexmtthresh) { + tcp_seq onxt = tp->snd_nxt; + + /* + * If we're doing sack, check to + * see if we're already in sack + * recovery. If we're not doing sack, + * check to see if we're in newreno + * recovery. + */ + if (SACK_ENABLED(tp)) { + if (IN_FASTRECOVERY(tp)) { + tp->t_dupacks = 0; + break; + } else if (tp->t_flagsext & TF_DELAY_RECOVERY) { + break; + } + } else { + if (SEQ_LEQ(th->th_ack, + tp->snd_recover)) { + tp->t_dupacks = 0; + break; + } + } + if (tp->t_flags & TF_SENTFIN) { + tp->snd_recover = tp->snd_max - 1; + } else { + tp->snd_recover = tp->snd_max; + } + tp->t_timer[TCPT_PTO] = 0; + tp->t_rtttime = 0; + + /* + * If the connection has seen pkt + * reordering, delay recovery until + * it is clear that the packet + * was lost. + */ + if (SACK_ENABLED(tp) && + (tp->t_flagsext & + (TF_PKTS_REORDERED | TF_DELAY_RECOVERY)) + == TF_PKTS_REORDERED && + !IN_FASTRECOVERY(tp) && + tp->t_reorderwin > 0 && + (tp->t_state == TCPS_ESTABLISHED || + tp->t_state == TCPS_FIN_WAIT_1)) { + tp->t_timer[TCPT_DELAYFR] = + OFFSET_FROM_START(tp, + tp->t_reorderwin); + tp->t_flagsext |= TF_DELAY_RECOVERY; + tcpstat.tcps_delay_recovery++; + tcp_ccdbg_trace(tp, th, + TCP_CC_DELAY_FASTRECOVERY); + break; + } + + tcp_rexmt_save_state(tp); + /* + * If the current tcp cc module has + * defined a hook for tasks to run + * before entering FR, call it + */ + if (CC_ALGO(tp)->pre_fr != NULL) { + CC_ALGO(tp)->pre_fr(tp); + } + ENTER_FASTRECOVERY(tp); + tp->t_timer[TCPT_REXMT] = 0; + if (TCP_ECN_ENABLED(tp)) { + tp->ecn_flags |= TE_SENDCWR; + } + + if (SACK_ENABLED(tp)) { + tcpstat.tcps_sack_recovery_episode++; + tp->t_sack_recovery_episode++; + tp->sack_newdata = tp->snd_nxt; + tp->snd_cwnd = tp->t_maxseg; + tp->t_flagsext &= + ~TF_CWND_NONVALIDATED; + + /* Process any window updates */ + if (tiwin > tp->snd_wnd) { + tcp_update_window( + tp, thflags, + th, tiwin, tlen); + } + + tcp_ccdbg_trace(tp, th, + TCP_CC_ENTER_FASTRECOVERY); + (void) tcp_output(tp); + goto drop; + } + tp->snd_nxt = th->th_ack; + tp->snd_cwnd = tp->t_maxseg; + + /* Process any window updates */ + if (tiwin > tp->snd_wnd) { + tcp_update_window(tp, + thflags, + th, tiwin, tlen); + } + + (void) tcp_output(tp); + if (tp->t_flagsext & TF_CWND_NONVALIDATED) { + tcp_cc_adjust_nonvalidated_cwnd(tp); + } else { + tp->snd_cwnd = tp->snd_ssthresh + + tp->t_maxseg * tp->t_dupacks; + } + if (SEQ_GT(onxt, tp->snd_nxt)) { + tp->snd_nxt = onxt; + } + + tcp_ccdbg_trace(tp, th, + TCP_CC_ENTER_FASTRECOVERY); + goto drop; + } else if (limited_txmt && + ALLOW_LIMITED_TRANSMIT(tp) && + (!(SACK_ENABLED(tp)) || sack_bytes_acked > 0) && + (so->so_snd.sb_cc - (tp->snd_max - tp->snd_una)) > 0) { + u_int32_t incr = (tp->t_maxseg * tp->t_dupacks); + + /* Use Limited Transmit algorithm on the first two + * duplicate acks when there is new data to transmit + */ + tp->snd_cwnd += incr; + tcpstat.tcps_limited_txt++; + (void) tcp_output(tp); + + tcp_ccdbg_trace(tp, th, TCP_CC_LIMITED_TRANSMIT); + + /* Reset snd_cwnd back to normal */ + tp->snd_cwnd -= incr; + } + } + break; + } + /* + * If the congestion window was inflated to account + * for the other side's cached packets, retract it. + */ + if (IN_FASTRECOVERY(tp)) { + if (SEQ_LT(th->th_ack, tp->snd_recover)) { + /* + * If we received an ECE and entered + * recovery, the subsequent ACKs should + * not be treated as partial acks. + */ + if (tp->ecn_flags & TE_INRECOVERY) { + goto process_ACK; + } + + if (SACK_ENABLED(tp)) { + tcp_sack_partialack(tp, th); + } else { + tcp_newreno_partial_ack(tp, th); + } + tcp_ccdbg_trace(tp, th, TCP_CC_PARTIAL_ACK); + } else { + EXIT_FASTRECOVERY(tp); + if (CC_ALGO(tp)->post_fr != NULL) { + CC_ALGO(tp)->post_fr(tp, th); + } + tp->t_pipeack = 0; + tcp_clear_pipeack_state(tp); + tcp_ccdbg_trace(tp, th, + TCP_CC_EXIT_FASTRECOVERY); + } + } else if ((tp->t_flagsext & + (TF_PKTS_REORDERED | TF_DELAY_RECOVERY)) + == (TF_PKTS_REORDERED | TF_DELAY_RECOVERY)) { + /* + * If the ack acknowledges upto snd_recover or if + * it acknowledges all the snd holes, exit + * recovery and cancel the timer. Otherwise, + * this is a partial ack. Wait for recovery timer + * to enter recovery. The snd_holes have already + * been updated. + */ + if (SEQ_GEQ(th->th_ack, tp->snd_recover) || + TAILQ_EMPTY(&tp->snd_holes)) { + tp->t_timer[TCPT_DELAYFR] = 0; + tp->t_flagsext &= ~TF_DELAY_RECOVERY; + EXIT_FASTRECOVERY(tp); + tcp_ccdbg_trace(tp, th, + TCP_CC_EXIT_FASTRECOVERY); + } + } else { + /* + * We were not in fast recovery. Reset the + * duplicate ack counter. + */ + tp->t_dupacks = 0; + tp->t_rexmtthresh = tcprexmtthresh; + } + + + /* + * If we reach this point, ACK is not a duplicate, + * i.e., it ACKs something we sent. + */ + if (tp->t_flags & TF_NEEDSYN) { + /* + * T/TCP: Connection was half-synchronized, and our + * SYN has been ACK'd (so connection is now fully + * synchronized). Go to non-starred state, + * increment snd_una for ACK of SYN, and check if + * we can do window scaling. + */ + tp->t_flags &= ~TF_NEEDSYN; + tp->snd_una++; + /* Do window scaling? */ + if (TCP_WINDOW_SCALE_ENABLED(tp)) { + tp->snd_scale = tp->requested_s_scale; + tp->rcv_scale = tp->request_r_scale; + } + } + +process_ACK: + VERIFY(SEQ_GEQ(th->th_ack, tp->snd_una)); + acked = BYTES_ACKED(th, tp); + tcpstat.tcps_rcvackpack++; + tcpstat.tcps_rcvackbyte += acked; + + /* + * If the last packet was a retransmit, make sure + * it was not spurious. + * + * This will also take care of congestion window + * adjustment if a last packet was recovered due to a + * tail loss probe. + */ + tcp_bad_rexmt_check(tp, th, &to); + + /* Recalculate the RTT */ + tcp_compute_rtt(tp, &to, th); + + /* + * If all outstanding data is acked, stop retransmit + * timer and remember to restart (more output or persist). + * If there is more data to be acked, restart retransmit + * timer, using current (possibly backed-off) value. + */ + TCP_RESET_REXMT_STATE(tp); + TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), + tp->t_rttmin, TCPTV_REXMTMAX, + TCP_ADD_REXMTSLOP(tp)); + if (th->th_ack == tp->snd_max) { + tp->t_timer[TCPT_REXMT] = 0; + tp->t_timer[TCPT_PTO] = 0; + needoutput = 1; + } else if (tp->t_timer[TCPT_PERSIST] == 0) { + tp->t_timer[TCPT_REXMT] = OFFSET_FROM_START(tp, + tp->t_rxtcur); + } + + if ((prev_t_state == TCPS_SYN_SENT || + prev_t_state == TCPS_SYN_RECEIVED) && + tp->t_state == TCPS_ESTABLISHED) { + TCP_LOG_RTT_INFO(tp); + } + + /* + * If no data (only SYN) was ACK'd, skip rest of ACK + * processing. + */ + if (acked == 0) { + goto step6; + } + + /* + * When outgoing data has been acked (except the SYN+data), we + * mark this connection as "sending good" for TFO. + */ + if ((tp->t_tfo_stats & TFO_S_SYN_DATA_SENT) && + !(tp->t_tfo_flags & TFO_F_NO_SNDPROBING) && + !(th->th_flags & TH_SYN)) { + tp->t_tfo_flags |= TFO_F_NO_SNDPROBING; + } + + /* + * If TH_ECE is received, make sure that ECN is enabled + * on that connection and we have sent ECT on data packets. + */ + if ((thflags & TH_ECE) != 0 && TCP_ECN_ENABLED(tp) && + (tp->ecn_flags & TE_SENDIPECT)) { + /* + * Reduce the congestion window if we haven't + * done so. + */ + if (!IN_FASTRECOVERY(tp)) { + tcp_reduce_congestion_window(tp); + tp->ecn_flags |= (TE_INRECOVERY | TE_SENDCWR); + /* + * Also note that the connection received + * ECE atleast once + */ + tp->ecn_flags |= TE_RECV_ECN_ECE; + INP_INC_IFNET_STAT(inp, ecn_recv_ece); + tcpstat.tcps_ecn_recv_ece++; + tcp_ccdbg_trace(tp, th, TCP_CC_ECN_RCVD); + } + } + + /* + * When new data is acked, open the congestion window. + * The specifics of how this is achieved are up to the + * congestion control algorithm in use for this connection. + * + * The calculations in this function assume that snd_una is + * not updated yet. + */ + if (!IN_FASTRECOVERY(tp)) { + if (CC_ALGO(tp)->ack_rcvd != NULL) { + CC_ALGO(tp)->ack_rcvd(tp, th); + } + tcp_ccdbg_trace(tp, th, TCP_CC_ACK_RCVD); + } + if (acked > so->so_snd.sb_cc) { + tp->snd_wnd -= so->so_snd.sb_cc; + sbdrop(&so->so_snd, (int)so->so_snd.sb_cc); + if (so->so_flags & SOF_ENABLE_MSGS) { + so->so_msg_state->msg_serial_bytes -= + (int)so->so_snd.sb_cc; + } + ourfinisacked = 1; + } else { + sbdrop(&so->so_snd, acked); + if (so->so_flags & SOF_ENABLE_MSGS) { + so->so_msg_state->msg_serial_bytes -= + acked; + } + tcp_sbsnd_trim(&so->so_snd); + tp->snd_wnd -= acked; + ourfinisacked = 0; + } + /* detect una wraparound */ + if (!IN_FASTRECOVERY(tp) && + SEQ_GT(tp->snd_una, tp->snd_recover) && + SEQ_LEQ(th->th_ack, tp->snd_recover)) { + tp->snd_recover = th->th_ack - 1; + } + + if (IN_FASTRECOVERY(tp) && + SEQ_GEQ(th->th_ack, tp->snd_recover)) { + EXIT_FASTRECOVERY(tp); + } + + tp->snd_una = th->th_ack; + + if (SACK_ENABLED(tp)) { + if (SEQ_GT(tp->snd_una, tp->snd_recover)) { + tp->snd_recover = tp->snd_una; + } + } + if (SEQ_LT(tp->snd_nxt, tp->snd_una)) { + tp->snd_nxt = tp->snd_una; + } + if (!SLIST_EMPTY(&tp->t_rxt_segments) && + !TCP_DSACK_SEQ_IN_WINDOW(tp, tp->t_dsack_lastuna, + tp->snd_una)) { + tcp_rxtseg_clean(tp); + } + if ((tp->t_flagsext & TF_MEASURESNDBW) != 0 && + tp->t_bwmeas != NULL) { + tcp_bwmeas_check(tp); + } + + write_wakeup = 1; + + if (!SLIST_EMPTY(&tp->t_notify_ack)) { + tcp_notify_acknowledgement(tp, so); + } + + switch (tp->t_state) { + /* + * In FIN_WAIT_1 STATE in addition to the processing + * for the ESTABLISHED state if our FIN is now acknowledged + * then enter FIN_WAIT_2. + */ + case TCPS_FIN_WAIT_1: + if (ourfinisacked) { + /* + * If we can't receive any more + * data, then closing user can proceed. + * Starting the TCPT_2MSL timer is contrary to the + * specification, but if we don't get a FIN + * we'll hang forever. + */ + if (so->so_state & SS_CANTRCVMORE) { + tp->t_timer[TCPT_2MSL] = OFFSET_FROM_START(tp, + TCP_CONN_MAXIDLE(tp)); + isconnected = FALSE; + isdisconnected = TRUE; + } + DTRACE_TCP4(state__change, void, NULL, + struct inpcb *, inp, + struct tcpcb *, tp, + int32_t, TCPS_FIN_WAIT_2); + tp->t_state = TCPS_FIN_WAIT_2; + /* fall through and make sure we also recognize + * data ACKed with the FIN + */ + } + break; + + /* + * In CLOSING STATE in addition to the processing for + * the ESTABLISHED state if the ACK acknowledges our FIN + * then enter the TIME-WAIT state, otherwise ignore + * the segment. + */ + case TCPS_CLOSING: + if (ourfinisacked) { + DTRACE_TCP4(state__change, void, NULL, + struct inpcb *, inp, + struct tcpcb *, tp, + int32_t, TCPS_TIME_WAIT); + tp->t_state = TCPS_TIME_WAIT; + tcp_canceltimers(tp); + if (tp->t_flagsext & TF_NOTIMEWAIT) { + tp->t_flags |= TF_CLOSING; + } else { + add_to_time_wait(tp, 2 * tcp_msl); + } + isconnected = FALSE; + isdisconnected = TRUE; + } + break; + + /* + * In LAST_ACK, we may still be waiting for data to drain + * and/or to be acked, as well as for the ack of our FIN. + * If our FIN is now acknowledged, delete the TCB, + * enter the closed state and return. + */ + case TCPS_LAST_ACK: + if (ourfinisacked) { + tp = tcp_close(tp); + goto drop; + } + break; + + /* + * In TIME_WAIT state the only thing that should arrive + * is a retransmission of the remote FIN. Acknowledge + * it and restart the finack timer. + */ + case TCPS_TIME_WAIT: + add_to_time_wait(tp, 2 * tcp_msl); + goto dropafterack; + } + + /* + * If there is a SACK option on the ACK and we + * haven't seen any duplicate acks before, count + * it as a duplicate ack even if the cumulative + * ack is advanced. If the receiver delayed an + * ack and detected loss afterwards, then the ack + * will advance cumulative ack and will also have + * a SACK option. So counting it as one duplicate + * ack is ok. + */ + if (sack_ackadv == 1 && + tp->t_state == TCPS_ESTABLISHED && + SACK_ENABLED(tp) && sack_bytes_acked > 0 && + to.to_nsacks > 0 && tp->t_dupacks == 0 && + SEQ_LEQ(th->th_ack, tp->snd_una) && tlen == 0 && + !(tp->t_flagsext & TF_PKTS_REORDERED)) { + tcpstat.tcps_sack_ackadv++; + goto process_dupack; + } + } + +step6: + /* + * Update window information. + */ + if (tcp_update_window(tp, thflags, th, tiwin, tlen)) { + needoutput = 1; + } + + /* + * Process segments with URG. + */ + if ((thflags & TH_URG) && th->th_urp && + TCPS_HAVERCVDFIN(tp->t_state) == 0) { + /* + * This is a kludge, but if we receive and accept + * random urgent pointers, we'll crash in + * soreceive. It's hard to imagine someone + * actually wanting to send this much urgent data. + */ + if (th->th_urp + so->so_rcv.sb_cc > sb_max) { + th->th_urp = 0; /* XXX */ + thflags &= ~TH_URG; /* XXX */ + goto dodata; /* XXX */ + } + /* + * If this segment advances the known urgent pointer, + * then mark the data stream. This should not happen + * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since + * a FIN has been received from the remote side. + * In these states we ignore the URG. + * + * According to RFC961 (Assigned Protocols), + * the urgent pointer points to the last octet + * of urgent data. We continue, however, + * to consider it to indicate the first octet + * of data past the urgent section as the original + * spec states (in one of two places). + */ + if (SEQ_GT(th->th_seq + th->th_urp, tp->rcv_up)) { + tp->rcv_up = th->th_seq + th->th_urp; + so->so_oobmark = so->so_rcv.sb_cc + + (tp->rcv_up - tp->rcv_nxt) - 1; + if (so->so_oobmark == 0) { + so->so_state |= SS_RCVATMARK; + postevent(so, 0, EV_OOB); + } + sohasoutofband(so); + tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); + } + /* + * Remove out of band data so doesn't get presented to user. + * This can happen independent of advancing the URG pointer, + * but if two URG's are pending at once, some out-of-band + * data may creep in... ick. + */ + if (th->th_urp <= (u_int32_t)tlen +#if SO_OOBINLINE + && (so->so_options & SO_OOBINLINE) == 0 +#endif + ) { + tcp_pulloutofband(so, th, m, + drop_hdrlen); /* hdr drop is delayed */ + } + } else { + /* + * If no out of band data is expected, + * pull receive urgent pointer along + * with the receive window. + */ + if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) { + tp->rcv_up = tp->rcv_nxt; + } + } +dodata: + + /* Set socket's connect or disconnect state correcly before doing data. + * The following might unlock the socket if there is an upcall or a socket + * filter. + */ + if (isconnected) { + soisconnected(so); + } else if (isdisconnected) { + soisdisconnected(so); + } + + /* Let's check the state of pcb just to make sure that it did not get closed + * when we unlocked above + */ + if (inp->inp_state == INPCB_STATE_DEAD) { + /* Just drop the packet that we are processing and return */ + TCP_LOG_DROP_PCB(TCP_LOG_HDR, th, tp, false, "INPCB_STATE_DEAD"); + goto drop; + } + + /* + * Process the segment text, merging it into the TCP sequencing queue, + * and arranging for acknowledgment of receipt if necessary. + * This process logically involves adjusting tp->rcv_wnd as data + * is presented to the user (this happens in tcp_usrreq.c, + * case PRU_RCVD). If a FIN has already been received on this + * connection then we just ignore the text. + * + * If we are in SYN-received state and got a valid TFO cookie, we want + * to process the data. + */ + if ((tlen || (thflags & TH_FIN)) && + TCPS_HAVERCVDFIN(tp->t_state) == 0 && + (TCPS_HAVEESTABLISHED(tp->t_state) || + (tp->t_state == TCPS_SYN_RECEIVED && + (tp->t_tfo_flags & TFO_F_COOKIE_VALID)))) { + tcp_seq save_start = th->th_seq; + tcp_seq save_end = th->th_seq + tlen; + m_adj(m, drop_hdrlen); /* delayed header drop */ + /* + * Insert segment which includes th into TCP reassembly queue + * with control block tp. Set thflags to whether reassembly now + * includes a segment with FIN. This handles the common case + * inline (segment is the next to be received on an established + * connection, and the queue is empty), avoiding linkage into + * and removal from the queue and repetition of various + * conversions. + * Set DELACK for segments received in order, but ack + * immediately when segments are out of order (so + * fast retransmit can work). + */ + if (th->th_seq == tp->rcv_nxt && LIST_EMPTY(&tp->t_segq)) { + TCP_INC_VAR(tp->t_unacksegs, nlropkts); + /* + * Calculate the RTT on the receiver only if the + * connection is in streaming mode and the last + * packet was not an end-of-write + */ + if (tp->t_flags & TF_STREAMING_ON) { + tcp_compute_rtt(tp, &to, th); + } + + if (DELAY_ACK(tp, th) && + ((tp->t_flags & TF_ACKNOW) == 0)) { + if ((tp->t_flags & TF_DELACK) == 0) { + tp->t_flags |= TF_DELACK; + tp->t_timer[TCPT_DELACK] = + OFFSET_FROM_START(tp, tcp_delack); + } + } else { + tp->t_flags |= TF_ACKNOW; + } + tp->rcv_nxt += tlen; + thflags = th->th_flags & TH_FIN; + TCP_INC_VAR(tcpstat.tcps_rcvpack, nlropkts); + tcpstat.tcps_rcvbyte += tlen; + if (nstat_collect) { + if (m->m_pkthdr.pkt_flags & PKTF_SW_LRO_PKT) { + INP_ADD_STAT(inp, cell, wifi, wired, + rxpackets, m->m_pkthdr.lro_npkts); + } else { + INP_ADD_STAT(inp, cell, wifi, wired, + rxpackets, 1); + } + INP_ADD_STAT(inp, cell, wifi, wired, + rxbytes, tlen); + inp_set_activity_bitmap(inp); + } + tcp_sbrcv_grow(tp, &so->so_rcv, &to, tlen, + TCP_AUTORCVBUF_MAX(ifp)); + so_recv_data_stat(so, m, drop_hdrlen); + + if (isipv6) { + memcpy(&saved_hdr, ip6, sizeof(struct ip6_hdr)); + ip6 = (struct ip6_hdr *)&saved_hdr[0]; + } else { + memcpy(&saved_hdr, ip, ip->ip_hl << 2); + ip = (struct ip *)&saved_hdr[0]; + } + memcpy(&saved_tcphdr, th, sizeof(struct tcphdr)); + if (sbappendstream_rcvdemux(so, m, + th->th_seq - (tp->irs + 1), 0)) { + read_wakeup = 1; + } + th = &saved_tcphdr; + } else { + if (isipv6) { + memcpy(&saved_hdr, ip6, sizeof(struct ip6_hdr)); + ip6 = (struct ip6_hdr *)&saved_hdr[0]; + } else { + memcpy(&saved_hdr, ip, ip->ip_hl << 2); + ip = (struct ip *)&saved_hdr[0]; + } + memcpy(&saved_tcphdr, th, sizeof(struct tcphdr)); + thflags = tcp_reass(tp, th, &tlen, m, ifp, &read_wakeup); + th = &saved_tcphdr; + tp->t_flags |= TF_ACKNOW; + } + + if ((tlen > 0 || (th->th_flags & TH_FIN)) && SACK_ENABLED(tp)) { + if (th->th_flags & TH_FIN) { + save_end++; + } + tcp_update_sack_list(tp, save_start, save_end); + } + + tcp_adaptive_rwtimo_check(tp, tlen); + + if (tlen > 0) { + tcp_tfo_rcv_data(tp); + } + + if (tp->t_flags & TF_DELACK) { +#if INET6 + if (isipv6) { + KERNEL_DEBUG(DBG_LAYER_END, ((th->th_dport << 16) | th->th_sport), + (((ip6->ip6_src.s6_addr16[0]) << 16) | (ip6->ip6_dst.s6_addr16[0])), + th->th_seq, th->th_ack, th->th_win); + } else +#endif + { + KERNEL_DEBUG(DBG_LAYER_END, ((th->th_dport << 16) | th->th_sport), + (((ip->ip_src.s_addr & 0xffff) << 16) | (ip->ip_dst.s_addr & 0xffff)), + th->th_seq, th->th_ack, th->th_win); + } + } + } else { + if ((so->so_flags & SOF_MP_SUBFLOW) && tlen == 0 && + (m->m_pkthdr.pkt_flags & PKTF_MPTCP_DFIN) && + (m->m_pkthdr.pkt_flags & PKTF_MPTCP)) { + m_adj(m, drop_hdrlen); /* delayed header drop */ + mptcp_input(tptomptp(tp)->mpt_mpte, m); + tp->t_flags |= TF_ACKNOW; + } else { + m_freem(m); + } + thflags &= ~TH_FIN; + } + + /* + * If FIN is received ACK the FIN and let the user know + * that the connection is closing. + */ + if (thflags & TH_FIN) { + if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { + socantrcvmore(so); + postevent(so, 0, EV_FIN); + /* + * If connection is half-synchronized + * (ie NEEDSYN flag on) then delay ACK, + * so it may be piggybacked when SYN is sent. + * Otherwise, since we received a FIN then no + * more input can be expected, send ACK now. + */ + TCP_INC_VAR(tp->t_unacksegs, nlropkts); + if (DELAY_ACK(tp, th) && (tp->t_flags & TF_NEEDSYN)) { + if ((tp->t_flags & TF_DELACK) == 0) { + tp->t_flags |= TF_DELACK; + tp->t_timer[TCPT_DELACK] = OFFSET_FROM_START(tp, tcp_delack); + } + } else { + tp->t_flags |= TF_ACKNOW; + } + tp->rcv_nxt++; + } + switch (tp->t_state) { + /* + * In SYN_RECEIVED and ESTABLISHED STATES + * enter the CLOSE_WAIT state. + */ + case TCPS_SYN_RECEIVED: + tp->t_starttime = tcp_now; + case TCPS_ESTABLISHED: + DTRACE_TCP4(state__change, void, NULL, struct inpcb *, inp, + struct tcpcb *, tp, int32_t, TCPS_CLOSE_WAIT); + tp->t_state = TCPS_CLOSE_WAIT; + break; + + /* + * If still in FIN_WAIT_1 STATE FIN has not been acked so + * enter the CLOSING state. + */ + case TCPS_FIN_WAIT_1: + DTRACE_TCP4(state__change, void, NULL, struct inpcb *, inp, + struct tcpcb *, tp, int32_t, TCPS_CLOSING); + tp->t_state = TCPS_CLOSING; + break; + + /* + * In FIN_WAIT_2 state enter the TIME_WAIT state, + * starting the time-wait timer, turning off the other + * standard timers. + */ + case TCPS_FIN_WAIT_2: + DTRACE_TCP4(state__change, void, NULL, + struct inpcb *, inp, + struct tcpcb *, tp, + int32_t, TCPS_TIME_WAIT); + tp->t_state = TCPS_TIME_WAIT; + tcp_canceltimers(tp); + tp->t_flags |= TF_ACKNOW; + if (tp->t_flagsext & TF_NOTIMEWAIT) { + tp->t_flags |= TF_CLOSING; + } else { + add_to_time_wait(tp, 2 * tcp_msl); + } + soisdisconnected(so); + break; + + /* + * In TIME_WAIT state restart the 2 MSL time_wait timer. + */ + case TCPS_TIME_WAIT: + add_to_time_wait(tp, 2 * tcp_msl); + break; + } + } +#if TCPDEBUG + if (so->so_options & SO_DEBUG) { + tcp_trace(TA_INPUT, ostate, tp, (void *)tcp_saveipgen, + &tcp_savetcp, 0); + } +#endif + + if (read_wakeup) { + mptcp_handle_input(so); + } + + /* + * Return any desired output. + */ + if (needoutput || (tp->t_flags & TF_ACKNOW)) { + (void) tcp_output(tp); + } + + tcp_check_timer_state(tp); + + tcp_handle_wakeup(so, read_wakeup, write_wakeup); + + socket_unlock(so, 1); + KERNEL_DEBUG(DBG_FNC_TCP_INPUT | DBG_FUNC_END, 0, 0, 0, 0, 0); + return; + +dropafterack: + /* + * Generate an ACK dropping incoming segment if it occupies + * sequence space, where the ACK reflects our state. + * + * We can now skip the test for the RST flag since all + * paths to this code happen after packets containing + * RST have been dropped. + * + * In the SYN-RECEIVED state, don't send an ACK unless the + * segment we received passes the SYN-RECEIVED ACK test. + * If it fails send a RST. This breaks the loop in the + * "LAND" DoS attack, and also prevents an ACK storm + * between two listening ports that have been sent forged + * SYN segments, each with the source address of the other. + */ + if (tp->t_state == TCPS_SYN_RECEIVED && (thflags & TH_ACK) && + (SEQ_GT(tp->snd_una, th->th_ack) || + SEQ_GT(th->th_ack, tp->snd_max))) { + rstreason = BANDLIM_RST_OPENPORT; + IF_TCP_STATINC(ifp, dospacket); + goto dropwithreset; + } +#if TCPDEBUG + if (so->so_options & SO_DEBUG) { + tcp_trace(TA_DROP, ostate, tp, (void *)tcp_saveipgen, + &tcp_savetcp, 0); + } +#endif + m_freem(m); + tp->t_flags |= TF_ACKNOW; + + (void) tcp_output(tp); + + tcp_handle_wakeup(so, read_wakeup, write_wakeup); + + /* Don't need to check timer state as we should have done it during tcp_output */ + socket_unlock(so, 1); + KERNEL_DEBUG(DBG_FNC_TCP_INPUT | DBG_FUNC_END, 0, 0, 0, 0, 0); + return; +dropwithresetnosock: + nosock = 1; +dropwithreset: + /* + * Generate a RST, dropping incoming segment. + * Make ACK acceptable to originator of segment. + * Don't bother to respond if destination was broadcast/multicast. + */ + if ((thflags & TH_RST) || m->m_flags & (M_BCAST | M_MCAST)) { + goto drop; + } +#if INET6 + if (isipv6) { + if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || + IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) { + goto drop; + } + } else +#endif /* INET6 */ + if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || + IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || + ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || + in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) { + goto drop; + } + /* IPv6 anycast check is done at tcp6_input() */ + + /* + * Perform bandwidth limiting. + */ +#if ICMP_BANDLIM + if (badport_bandlim(rstreason) < 0) { + goto drop; + } +#endif + +#if TCPDEBUG + if (tp == 0 || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) { + tcp_trace(TA_DROP, ostate, tp, (void *)tcp_saveipgen, + &tcp_savetcp, 0); + } +#endif + bzero(&tra, sizeof(tra)); + tra.ifscope = ifscope; + tra.awdl_unrestricted = 1; + tra.intcoproc_allowed = 1; + if (thflags & TH_ACK) { + /* mtod() below is safe as long as hdr dropping is delayed */ + tcp_respond(tp, mtod(m, void *), th, m, (tcp_seq)0, th->th_ack, + TH_RST, &tra); + } else { + if (thflags & TH_SYN) { + tlen++; + } + /* mtod() below is safe as long as hdr dropping is delayed */ + tcp_respond(tp, mtod(m, void *), th, m, th->th_seq + tlen, + (tcp_seq)0, TH_RST | TH_ACK, &tra); + } + /* destroy temporarily created socket */ + if (dropsocket) { + (void) soabort(so); + socket_unlock(so, 1); + } else if ((inp != NULL) && (nosock == 0)) { + tcp_handle_wakeup(so, read_wakeup, write_wakeup); + + socket_unlock(so, 1); + } + KERNEL_DEBUG(DBG_FNC_TCP_INPUT | DBG_FUNC_END, 0, 0, 0, 0, 0); + return; +dropnosock: + nosock = 1; +drop: + /* + * Drop space held by incoming segment and return. + */ +#if TCPDEBUG + if (tp == 0 || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) { + tcp_trace(TA_DROP, ostate, tp, (void *)tcp_saveipgen, + &tcp_savetcp, 0); + } +#endif + m_freem(m); + /* destroy temporarily created socket */ + if (dropsocket) { + (void) soabort(so); + socket_unlock(so, 1); + } else if (nosock == 0) { + tcp_handle_wakeup(so, read_wakeup, write_wakeup); + + socket_unlock(so, 1); + } + KERNEL_DEBUG(DBG_FNC_TCP_INPUT | DBG_FUNC_END, 0, 0, 0, 0, 0); + return; +} + +/* + * Parse TCP options and place in tcpopt. + */ +static void +tcp_dooptions(struct tcpcb *tp, u_char *cp, int cnt, struct tcphdr *th, + struct tcpopt *to) +{ + u_short mss = 0; + int opt, optlen; + + for (; cnt > 0; cnt -= optlen, cp += optlen) { + opt = cp[0]; + if (opt == TCPOPT_EOL) { + break; + } + if (opt == TCPOPT_NOP) { + optlen = 1; + } else { + if (cnt < 2) { + break; + } + optlen = cp[1]; + if (optlen < 2 || optlen > cnt) { + break; + } + } + switch (opt) { + default: + continue; + + case TCPOPT_MAXSEG: + if (optlen != TCPOLEN_MAXSEG) { + continue; + } + if (!(th->th_flags & TH_SYN)) { + continue; + } + bcopy((char *) cp + 2, (char *) &mss, sizeof(mss)); + NTOHS(mss); + to->to_mss = mss; + to->to_flags |= TOF_MSS; + break; + + case TCPOPT_WINDOW: + if (optlen != TCPOLEN_WINDOW) { + continue; + } + if (!(th->th_flags & TH_SYN)) { + continue; + } + to->to_flags |= TOF_SCALE; + to->to_requested_s_scale = min(cp[2], TCP_MAX_WINSHIFT); + break; + + case TCPOPT_TIMESTAMP: + if (optlen != TCPOLEN_TIMESTAMP) { + continue; + } + to->to_flags |= TOF_TS; + bcopy((char *)cp + 2, + (char *)&to->to_tsval, sizeof(to->to_tsval)); + NTOHL(to->to_tsval); + bcopy((char *)cp + 6, + (char *)&to->to_tsecr, sizeof(to->to_tsecr)); + NTOHL(to->to_tsecr); + /* Re-enable sending Timestamps if we received them */ + if (!(tp->t_flags & TF_REQ_TSTMP) && + tcp_do_rfc1323 == 1) { + tp->t_flags |= TF_REQ_TSTMP; + } + break; + case TCPOPT_SACK_PERMITTED: + if (!tcp_do_sack || + optlen != TCPOLEN_SACK_PERMITTED) { + continue; + } + if (th->th_flags & TH_SYN) { + to->to_flags |= TOF_SACK; + } + break; + case TCPOPT_SACK: + if (optlen <= 2 || (optlen - 2) % TCPOLEN_SACK != 0) { + continue; + } + to->to_nsacks = (optlen - 2) / TCPOLEN_SACK; + to->to_sacks = cp + 2; + tcpstat.tcps_sack_rcv_blocks++; + + break; + case TCPOPT_FASTOPEN: + if (optlen == TCPOLEN_FASTOPEN_REQ) { + if (tp->t_state != TCPS_LISTEN) { + continue; + } + + to->to_flags |= TOF_TFOREQ; + } else { + if (optlen < TCPOLEN_FASTOPEN_REQ || + (optlen - TCPOLEN_FASTOPEN_REQ) > TFO_COOKIE_LEN_MAX || + (optlen - TCPOLEN_FASTOPEN_REQ) < TFO_COOKIE_LEN_MIN) { + continue; + } + if (tp->t_state != TCPS_LISTEN && + tp->t_state != TCPS_SYN_SENT) { + continue; + } + + to->to_flags |= TOF_TFO; + to->to_tfo = cp + 1; + } + + break; +#if MPTCP + case TCPOPT_MULTIPATH: + tcp_do_mptcp_options(tp, cp, th, to, optlen); + break; +#endif /* MPTCP */ + } + } +} + +static void +tcp_finalize_options(struct tcpcb *tp, struct tcpopt *to, unsigned int ifscope) +{ + if (to->to_flags & TOF_TS) { + tp->t_flags |= TF_RCVD_TSTMP; + tp->ts_recent = to->to_tsval; + tp->ts_recent_age = tcp_now; + } + if (to->to_flags & TOF_MSS) { + tcp_mss(tp, to->to_mss, ifscope); + } + if (SACK_ENABLED(tp)) { + if (!(to->to_flags & TOF_SACK)) { + tp->t_flagsext &= ~(TF_SACK_ENABLE); + } else { + tp->t_flags |= TF_SACK_PERMIT; + } + } + if (to->to_flags & TOF_SCALE) { + tp->t_flags |= TF_RCVD_SCALE; + tp->requested_s_scale = to->to_requested_s_scale; + + /* Re-enable window scaling, if the option is received */ + if (tp->request_r_scale > 0) { + tp->t_flags |= TF_REQ_SCALE; + } + } +} + +/* + * Pull out of band byte out of a segment so + * it doesn't appear in the user's data queue. + * It is still reflected in the segment length for + * sequencing purposes. + * + * @param off delayed to be droped hdrlen + */ +static void +tcp_pulloutofband(struct socket *so, struct tcphdr *th, struct mbuf *m, int off) +{ + int cnt = off + th->th_urp - 1; + + while (cnt >= 0) { + if (m->m_len > cnt) { + char *cp = mtod(m, caddr_t) + cnt; + struct tcpcb *tp = sototcpcb(so); + + tp->t_iobc = *cp; + tp->t_oobflags |= TCPOOB_HAVEDATA; + bcopy(cp + 1, cp, (unsigned)(m->m_len - cnt - 1)); + m->m_len--; + if (m->m_flags & M_PKTHDR) { + m->m_pkthdr.len--; + } + return; + } + cnt -= m->m_len; + m = m->m_next; + if (m == 0) { + break; + } + } + panic("tcp_pulloutofband"); +} + +uint32_t +get_base_rtt(struct tcpcb *tp) +{ + struct rtentry *rt = tp->t_inpcb->inp_route.ro_rt; + return (rt == NULL) ? 0 : rt->rtt_min; +} + +/* Each value of RTT base represents the minimum RTT seen in a minute. + * We keep upto N_RTT_BASE minutes worth of history. + */ +void +update_base_rtt(struct tcpcb *tp, uint32_t rtt) +{ + u_int32_t base_rtt, i; + struct rtentry *rt; + + if ((rt = tp->t_inpcb->inp_route.ro_rt) == NULL) { + return; + } + if (rt->rtt_expire_ts == 0) { + RT_LOCK_SPIN(rt); + if (rt->rtt_expire_ts != 0) { + RT_UNLOCK(rt); + goto update; + } + rt->rtt_expire_ts = tcp_now; + rt->rtt_index = 0; + rt->rtt_hist[0] = rtt; + rt->rtt_min = rtt; + RT_UNLOCK(rt); + return; + } +update: +#if TRAFFIC_MGT + /* + * If the recv side is being throttled, check if the + * current RTT is closer to the base RTT seen in + * first (recent) two slots. If so, unthrottle the stream. + */ + if ((tp->t_flagsext & TF_RECV_THROTTLE) && + (int)(tcp_now - tp->t_recv_throttle_ts) >= TCP_RECV_THROTTLE_WIN) { + base_rtt = rt->rtt_min; + if (tp->t_rttcur <= (base_rtt + target_qdelay)) { + tp->t_flagsext &= ~TF_RECV_THROTTLE; + tp->t_recv_throttle_ts = 0; + } + } +#endif /* TRAFFIC_MGT */ + if ((int)(tcp_now - rt->rtt_expire_ts) >= + TCP_RTT_HISTORY_EXPIRE_TIME) { + RT_LOCK_SPIN(rt); + /* check the condition again to avoid race */ + if ((int)(tcp_now - rt->rtt_expire_ts) >= + TCP_RTT_HISTORY_EXPIRE_TIME) { + rt->rtt_index++; + if (rt->rtt_index >= NRTT_HIST) { + rt->rtt_index = 0; + } + rt->rtt_hist[rt->rtt_index] = rtt; + rt->rtt_expire_ts = tcp_now; + } else { + rt->rtt_hist[rt->rtt_index] = + min(rt->rtt_hist[rt->rtt_index], rtt); + } + /* forget the old value and update minimum */ + rt->rtt_min = 0; + for (i = 0; i < NRTT_HIST; ++i) { + if (rt->rtt_hist[i] != 0 && + (rt->rtt_min == 0 || + rt->rtt_hist[i] < rt->rtt_min)) { + rt->rtt_min = rt->rtt_hist[i]; + } + } + RT_UNLOCK(rt); + } else { + rt->rtt_hist[rt->rtt_index] = + min(rt->rtt_hist[rt->rtt_index], rtt); + if (rt->rtt_min == 0) { + rt->rtt_min = rtt; + } else { + rt->rtt_min = min(rt->rtt_min, rtt); + } + } +} + +/* + * If we have a timestamp reply, update smoothed RTT. If no timestamp is + * present but transmit timer is running and timed sequence number was + * acked, update smoothed RTT. + * + * If timestamps are supported, a receiver can update RTT even if + * there is no outstanding data. + * + * Some boxes send broken timestamp replies during the SYN+ACK phase, + * ignore timestamps of 0or we could calculate a huge RTT and blow up + * the retransmit timer. + */ +static void +tcp_compute_rtt(struct tcpcb *tp, struct tcpopt *to, struct tcphdr *th) +{ + int rtt = 0; + VERIFY(to != NULL && th != NULL); + if (tp->t_rtttime != 0 && SEQ_GT(th->th_ack, tp->t_rtseq)) { + u_int32_t pipe_ack_val; + rtt = tcp_now - tp->t_rtttime; + /* + * Compute pipe ack -- the amount of data acknowledged + * in the last RTT + */ + if (SEQ_GT(th->th_ack, tp->t_pipeack_lastuna)) { + pipe_ack_val = th->th_ack - tp->t_pipeack_lastuna; + /* Update the sample */ + tp->t_pipeack_sample[tp->t_pipeack_ind++] = + pipe_ack_val; + tp->t_pipeack_ind %= TCP_PIPEACK_SAMPLE_COUNT; + + /* Compute the max of the pipeack samples */ + pipe_ack_val = tcp_get_max_pipeack(tp); + tp->t_pipeack = (pipe_ack_val > + TCP_CC_CWND_INIT_BYTES) ? + pipe_ack_val : 0; + } + /* start another measurement */ + tp->t_rtttime = 0; + } + if (((to->to_flags & TOF_TS) != 0) && + (to->to_tsecr != 0) && + TSTMP_GEQ(tcp_now, to->to_tsecr)) { + tcp_xmit_timer(tp, (tcp_now - to->to_tsecr), + to->to_tsecr, th->th_ack); + } else if (rtt > 0) { + tcp_xmit_timer(tp, rtt, 0, th->th_ack); + } +} + +/* + * Collect new round-trip time estimate and update averages and + * current timeout. + */ +static void +tcp_xmit_timer(struct tcpcb *tp, int rtt, + u_int32_t tsecr, tcp_seq th_ack) +{ + int delta; + int old_srtt = tp->t_srtt; + int old_rttvar = tp->t_rttvar; + bool log_rtt = false; + + /* + * On AWDL interface, the initial RTT measurement on SYN + * can be wrong due to peer caching. Avoid the first RTT + * measurement as it might skew up the RTO. + * + */ + if (tp->t_inpcb->inp_last_outifp != NULL && + (tp->t_inpcb->inp_last_outifp->if_eflags & IFEF_AWDL) && + th_ack == tp->iss + 1) { + return; + } + + if (tp->t_flagsext & TF_RECOMPUTE_RTT) { + if (SEQ_GT(th_ack, tp->snd_una) && + SEQ_LEQ(th_ack, tp->snd_max) && + (tsecr == 0 || + TSTMP_GEQ(tsecr, tp->t_badrexmt_time))) { + /* + * We received a new ACk after a + * spurious timeout. Adapt retransmission + * timer as described in rfc 4015. + */ + tp->t_flagsext &= ~(TF_RECOMPUTE_RTT); + tp->t_badrexmt_time = 0; + tp->t_srtt = max(tp->t_srtt_prev, rtt); + tp->t_srtt = tp->t_srtt << TCP_RTT_SHIFT; + tp->t_rttvar = max(tp->t_rttvar_prev, (rtt >> 1)); + tp->t_rttvar = tp->t_rttvar << TCP_RTTVAR_SHIFT; + + if (tp->t_rttbest > (tp->t_srtt + tp->t_rttvar)) { + tp->t_rttbest = tp->t_srtt + tp->t_rttvar; + } + + goto compute_rto; + } else { + return; + } + } + + tcpstat.tcps_rttupdated++; + tp->t_rttupdated++; + + if (rtt > 0) { + tp->t_rttcur = rtt; + update_base_rtt(tp, rtt); + } + + if (tp->t_srtt != 0) { + /* + * srtt is stored as fixed point with 5 bits after the + * binary point (i.e., scaled by 32). The following magic + * is equivalent to the smoothing algorithm in rfc793 with + * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed + * point). + * + * Freebsd adjusts rtt to origin 0 by subtracting 1 + * from the provided rtt value. This was required because + * of the way t_rtttime was initiailised to 1 before. + * Since we changed t_rtttime to be based on + * tcp_now, this extra adjustment is not needed. + */ + delta = (rtt << TCP_DELTA_SHIFT) + - (tp->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT)); + + if ((tp->t_srtt += delta) <= 0) { + tp->t_srtt = 1; + } + + /* + * We accumulate a smoothed rtt variance (actually, a + * smoothed mean difference), then set the retransmit + * timer to smoothed rtt + 4 times the smoothed variance. + * rttvar is stored as fixed point with 4 bits after the + * binary point (scaled by 16). The following is + * equivalent to rfc793 smoothing with an alpha of .75 + * (rttvar = rttvar*3/4 + |delta| / 4). This replaces + * rfc793's wired-in beta. + */ + if (delta < 0) { + delta = -delta; + } + delta -= tp->t_rttvar >> (TCP_RTTVAR_SHIFT - TCP_DELTA_SHIFT); + if ((tp->t_rttvar += delta) <= 0) { + tp->t_rttvar = 1; + } + if (tp->t_rttbest == 0 || + tp->t_rttbest > (tp->t_srtt + tp->t_rttvar)) { + tp->t_rttbest = tp->t_srtt + tp->t_rttvar; + } + } else { + /* + * No rtt measurement yet - use the unsmoothed rtt. + * Set the variance to half the rtt (so our first + * retransmit happens at 3*rtt). + */ + tp->t_srtt = rtt << TCP_RTT_SHIFT; + tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1); + } + +compute_rto: + nstat_route_rtt(tp->t_inpcb->inp_route.ro_rt, tp->t_srtt, + tp->t_rttvar); + + /* + * the retransmit should happen at rtt + 4 * rttvar. + * Because of the way we do the smoothing, srtt and rttvar + * will each average +1/2 tick of bias. When we compute + * the retransmit timer, we want 1/2 tick of rounding and + * 1 extra tick because of +-1/2 tick uncertainty in the + * firing of the timer. The bias will give us exactly the + * 1.5 tick we need. But, because the bias is + * statistical, we have to test that we don't drop below + * the minimum feasible timer (which is 2 ticks). + */ + TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), + max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX, + TCP_ADD_REXMTSLOP(tp)); + + /* + * We received an ack for a packet that wasn't retransmitted; + * it is probably safe to discard any error indications we've + * received recently. This isn't quite right, but close enough + * for now (a route might have failed after we sent a segment, + * and the return path might not be symmetrical). + */ + tp->t_softerror = 0; + + if (log_rtt) { + TCP_LOG_RTT_INFO(tp); + } + + TCP_LOG_RTT_CHANGE(tp, old_srtt, old_rttvar); +} + +static inline unsigned int +tcp_maxmtu(struct rtentry *rt) +{ + unsigned int maxmtu; + int interface_mtu = 0; + + RT_LOCK_ASSERT_HELD(rt); + interface_mtu = rt->rt_ifp->if_mtu; + + if (rt_key(rt)->sa_family == AF_INET && + INTF_ADJUST_MTU_FOR_CLAT46(rt->rt_ifp)) { + interface_mtu = IN6_LINKMTU(rt->rt_ifp); + /* Further adjust the size for CLAT46 expansion */ + interface_mtu -= CLAT46_HDR_EXPANSION_OVERHD; + } + + if (rt->rt_rmx.rmx_mtu == 0) { + maxmtu = interface_mtu; + } else { + maxmtu = MIN(rt->rt_rmx.rmx_mtu, interface_mtu); + } + + return maxmtu; +} + +#if INET6 +static inline unsigned int +tcp_maxmtu6(struct rtentry *rt) +{ + unsigned int maxmtu; + struct nd_ifinfo *ndi = NULL; + + RT_LOCK_ASSERT_HELD(rt); + if ((ndi = ND_IFINFO(rt->rt_ifp)) != NULL && !ndi->initialized) { + ndi = NULL; + } + if (ndi != NULL) { + lck_mtx_lock(&ndi->lock); + } + if (rt->rt_rmx.rmx_mtu == 0) { + maxmtu = IN6_LINKMTU(rt->rt_ifp); + } else { + maxmtu = MIN(rt->rt_rmx.rmx_mtu, IN6_LINKMTU(rt->rt_ifp)); + } + if (ndi != NULL) { + lck_mtx_unlock(&ndi->lock); + } + + return maxmtu; +} +#endif + +unsigned int +get_maxmtu(struct rtentry *rt) +{ + unsigned int maxmtu = 0; + + RT_LOCK_ASSERT_NOTHELD(rt); + + RT_LOCK(rt); + + if (rt_key(rt)->sa_family == AF_INET6) { + maxmtu = tcp_maxmtu6(rt); + } else { + maxmtu = tcp_maxmtu(rt); + } + + RT_UNLOCK(rt); + + return maxmtu; +} + +/* + * Determine a reasonable value for maxseg size. + * If the route is known, check route for mtu. + * If none, use an mss that can be handled on the outgoing + * interface without forcing IP to fragment; if bigger than + * an mbuf cluster (MCLBYTES), round down to nearest multiple of MCLBYTES + * to utilize large mbufs. If no route is found, route has no mtu, + * or the destination isn't local, use a default, hopefully conservative + * size (usually 512 or the default IP max size, but no more than the mtu + * of the interface), as we can't discover anything about intervening + * gateways or networks. We also initialize the congestion/slow start + * window. While looking at the routing entry, we also initialize + * other path-dependent parameters from pre-set or cached values + * in the routing entry. + * + * Also take into account the space needed for options that we + * send regularly. Make maxseg shorter by that amount to assure + * that we can send maxseg amount of data even when the options + * are present. Store the upper limit of the length of options plus + * data in maxopd. + * + * NOTE that this routine is only called when we process an incoming + * segment, for outgoing segments only tcp_mssopt is called. + * + */ +void +tcp_mss(struct tcpcb *tp, int offer, unsigned int input_ifscope) +{ + struct rtentry *rt; + struct ifnet *ifp; + int rtt, mss; + u_int32_t bufsize; + struct inpcb *inp; + struct socket *so; + struct rmxp_tao *taop; + int origoffer = offer; + u_int32_t sb_max_corrected; + int isnetlocal = 0; +#if INET6 + int isipv6; + int min_protoh; +#endif - /* - * In CLOSING STATE in addition to the processing for - * the ESTABLISHED state if the ACK acknowledges our FIN - * then enter the TIME-WAIT state, otherwise ignore - * the segment. - */ - case TCPS_CLOSING: - if (ourfinisacked) { - tp->t_state = TCPS_TIME_WAIT; - tcp_canceltimers(tp); - /* Shorten TIME_WAIT [RFC-1644, p.28] */ - if (tp->cc_recv != 0 && - tp->t_duration < TCPTV_MSL) - tp->t_timer[TCPT_2MSL] = - tp->t_rxtcur * TCPTV_TWTRUNC; - else - tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; - add_to_time_wait(tp); - current_active_connections--; - soisdisconnected(so); - } - break; + inp = tp->t_inpcb; - /* - * In LAST_ACK, we may still be waiting for data to drain - * and/or to be acked, as well as for the ack of our FIN. - * If our FIN is now acknowledged, delete the TCB, - * enter the closed state and return. - */ - case TCPS_LAST_ACK: - if (ourfinisacked) { - tp = tcp_close(tp); - goto drop; - } - break; + so = inp->inp_socket; + /* + * Nothing left to send after the socket is defunct or TCP is in the closed state + */ + if ((so->so_state & SS_DEFUNCT) || tp->t_state == TCPS_CLOSED) { + return; + } - /* - * In TIME_WAIT state the only thing that should arrive - * is a retransmission of the remote FIN. Acknowledge - * it and restart the finack timer. - */ - case TCPS_TIME_WAIT: - tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; - add_to_time_wait(tp); - goto dropafterack; - } +#if INET6 + isipv6 = ((inp->inp_vflag & INP_IPV6) != 0) ? 1 : 0; + min_protoh = isipv6 ? sizeof(struct ip6_hdr) + sizeof(struct tcphdr) + : sizeof(struct tcpiphdr); +#else +#define min_protoh (sizeof (struct tcpiphdr)) +#endif + +#if INET6 + if (isipv6) { + rt = tcp_rtlookup6(inp, input_ifscope); + } else +#endif /* INET6 */ + { + rt = tcp_rtlookup(inp, input_ifscope); } + isnetlocal = (tp->t_flags & TF_LOCAL); -step6: + if (rt == NULL) { + tp->t_maxopd = tp->t_maxseg = +#if INET6 + isipv6 ? tcp_v6mssdflt : +#endif /* INET6 */ + tcp_mssdflt; + return; + } + ifp = rt->rt_ifp; /* - * Update window information. - * Don't look at window if no ACK: TAC's send garbage on first SYN. + * Slower link window correction: + * If a value is specificied for slowlink_wsize use it for + * PPP links believed to be on a serial modem (speed <128Kbps). + * Excludes 9600bps as it is the default value adversized + * by pseudo-devices over ppp. */ - if ((thflags & TH_ACK) && - (SEQ_LT(tp->snd_wl1, th->th_seq) || - (tp->snd_wl1 == th->th_seq && (SEQ_LT(tp->snd_wl2, th->th_ack) || - (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))) { - /* keep track of pure window updates */ - if (tilen == 0 && - tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) - tcpstat.tcps_rcvwinupd++; - tp->snd_wnd = tiwin; - tp->snd_wl1 = th->th_seq; - tp->snd_wl2 = th->th_ack; - if (tp->snd_wnd > tp->max_sndwnd) - tp->max_sndwnd = tp->snd_wnd; - needoutput = 1; + if (ifp->if_type == IFT_PPP && slowlink_wsize > 0 && + ifp->if_baudrate > 9600 && ifp->if_baudrate <= 128000) { + tp->t_flags |= TF_SLOWLINK; } + taop = rmx_taop(rt->rt_rmx); /* - * Process segments with URG. + * Offer == -1 means that we didn't receive SYN yet, + * use cached value in that case; */ - if ((thflags & TH_URG) && th->th_urp && - TCPS_HAVERCVDFIN(tp->t_state) == 0) { + if (offer == -1) { + offer = taop->tao_mssopt; + } + /* + * Offer == 0 means that there was no MSS on the SYN segment, + * in this case we use tcp_mssdflt. + */ + if (offer == 0) { + offer = +#if INET6 + isipv6 ? tcp_v6mssdflt : +#endif /* INET6 */ + tcp_mssdflt; + } else { /* - * This is a kludge, but if we receive and accept - * random urgent pointers, we'll crash in - * soreceive. It's hard to imagine someone - * actually wanting to send this much urgent data. + * Prevent DoS attack with too small MSS. Round up + * to at least minmss. */ - if (th->th_urp + so->so_rcv.sb_cc > sb_max) { - th->th_urp = 0; /* XXX */ - thflags &= ~TH_URG; /* XXX */ - goto dodata; /* XXX */ - } + offer = max(offer, tcp_minmss); /* - * If this segment advances the known urgent pointer, - * then mark the data stream. This should not happen - * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since - * a FIN has been received from the remote side. - * In these states we ignore the URG. - * - * According to RFC961 (Assigned Protocols), - * the urgent pointer points to the last octet - * of urgent data. We continue, however, - * to consider it to indicate the first octet - * of data past the urgent section as the original - * spec states (in one of two places). + * Sanity check: make sure that maxopd will be large + * enough to allow some data on segments even is the + * all the option space is used (40bytes). Otherwise + * funny things may happen in tcp_output. */ - if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) { - tp->rcv_up = th->th_seq + th->th_urp; - so->so_oobmark = so->so_rcv.sb_cc + - (tp->rcv_up - tp->rcv_nxt) - 1; - if (so->so_oobmark == 0) { - so->so_state |= SS_RCVATMARK; - postevent(so, 0, EV_OOB); + offer = max(offer, 64); + } + taop->tao_mssopt = offer; + + /* + * While we're here, check if there's an initial rtt + * or rttvar. Convert from the route-table units + * to scaled multiples of the slow timeout timer. + */ + if (tp->t_srtt == 0 && (rtt = rt->rt_rmx.rmx_rtt) != 0) { + tcp_getrt_rtt(tp, rt); + } else { + tp->t_rttmin = isnetlocal ? tcp_TCPTV_MIN : TCPTV_REXMTMIN; + } + +#if INET6 + mss = (isipv6 ? tcp_maxmtu6(rt) : tcp_maxmtu(rt)); +#else + mss = tcp_maxmtu(rt); +#endif + +#if NECP + // At this point, the mss is just the MTU. Adjust if necessary. + mss = necp_socket_get_effective_mtu(inp, mss); +#endif /* NECP */ + + mss -= min_protoh; + + if (rt->rt_rmx.rmx_mtu == 0) { +#if INET6 + if (isipv6) { + if (!isnetlocal) { + mss = min(mss, tcp_v6mssdflt); } - sohasoutofband(so); - tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); + } else +#endif /* INET6 */ + if (!isnetlocal) { + mss = min(mss, tcp_mssdflt); } - /* - * Remove out of band data so doesn't get presented to user. - * This can happen independent of advancing the URG pointer, - * but if two URG's are pending at once, some out-of-band - * data may creep in... ick. - */ - if (th->th_urp <= (u_long)tilen -#if SO_OOBINLINE - && (so->so_options & SO_OOBINLINE) == 0 -#endif - ) - tcp_pulloutofband(so, th, m); - } else - /* - * If no out of band data is expected, - * pull receive urgent pointer along - * with the receive window. - */ - if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) - tp->rcv_up = tp->rcv_nxt; -dodata: /* XXX */ + } + mss = min(mss, offer); /* - * Process the segment text, merging it into the TCP sequencing queue, - * and arranging for acknowledgment of receipt if necessary. - * This process logically involves adjusting tp->rcv_wnd as data - * is presented to the user (this happens in tcp_usrreq.c, - * case PRU_RCVD). If a FIN has already been received on this - * connection then we just ignore the text. + * maxopd stores the maximum length of data AND options + * in a segment; maxseg is the amount of data in a normal + * segment. We need to store this value (maxopd) apart + * from maxseg, because now every segment carries options + * and thus we normally have somewhat less data in segments. */ - if ((tilen || (thflags&TH_FIN)) && - TCPS_HAVERCVDFIN(tp->t_state) == 0) { - TCP_REASS(tp, th, tilen, m, so, thflags, isipv6, need_sorwakeup); + tp->t_maxopd = mss; - if (tp->t_flags & TF_DELACK) - { - KERNEL_DEBUG(DBG_LAYER_END, ((th->th_dport << 16) | th->th_sport), - (((thtoti(th)->ti_src.s_addr & 0xffff) << 16) | (thtoti(th)->ti_dst.s_addr & 0xffff)), - th->th_seq, th->th_ack, th->th_win); - } - /* - * Note the amount of data that peer has sent into - * our window, in order to estimate the sender's - * buffer size. - */ - len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); - } else { - m_freem(m); - thflags &= ~TH_FIN; + /* + * origoffer==-1 indicates, that no segments were received yet. + * In this case we just guess. + */ + if ((tp->t_flags & (TF_REQ_TSTMP | TF_NOOPT)) == TF_REQ_TSTMP && + (origoffer == -1 || + (tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP)) { + mss -= TCPOLEN_TSTAMP_APPA; } +#if MPTCP + mss -= mptcp_adj_mss(tp, FALSE); +#endif /* MPTCP */ + tp->t_maxseg = mss; + /* - * If FIN is received ACK the FIN and let the user know - * that the connection is closing. + * Calculate corrected value for sb_max; ensure to upgrade the + * numerator for large sb_max values else it will overflow. */ - if (thflags & TH_FIN) { - if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { - socantrcvmore(so); - postevent(so, 0, EV_FIN); - /* - * If connection is half-synchronized - * (ie NEEDSYN flag on) then delay ACK, - * so it may be piggybacked when SYN is sent. - * Otherwise, since we received a FIN then no - * more input can be expected, send ACK now. - */ - if (tcp_delack_enabled && (tp->t_flags & TF_NEEDSYN)) { - if (last_active_conn_count > DELACK_BITMASK_THRESH) - TCP_DELACK_BITSET(tp->t_inpcb->hash_element); + sb_max_corrected = (sb_max * (u_int64_t)MCLBYTES) / (MSIZE + MCLBYTES); - tp->t_flags |= TF_DELACK; - } - else - tp->t_flags |= TF_ACKNOW; - tp->rcv_nxt++; + /* + * If there's a pipesize (ie loopback), change the socket + * buffer to that size only if it's bigger than the current + * sockbuf size. Make the socket buffers an integral + * number of mss units; if the mss is larger than + * the socket buffer, decrease the mss. + */ +#if RTV_SPIPE + bufsize = rt->rt_rmx.rmx_sendpipe; + if (bufsize < so->so_snd.sb_hiwat) +#endif + bufsize = so->so_snd.sb_hiwat; + if (bufsize < mss) { + mss = bufsize; + } else { + bufsize = (((bufsize + (u_int64_t)mss - 1) / (u_int64_t)mss) * (u_int64_t)mss); + if (bufsize > sb_max_corrected) { + bufsize = sb_max_corrected; } - switch (tp->t_state) { + (void)sbreserve(&so->so_snd, bufsize); + } + tp->t_maxseg = mss; - /* - * In SYN_RECEIVED and ESTABLISHED STATES - * enter the CLOSE_WAIT state. - */ - case TCPS_SYN_RECEIVED: - case TCPS_ESTABLISHED: - tp->t_state = TCPS_CLOSE_WAIT; - break; + ASSERT(tp->t_maxseg); - /* - * If still in FIN_WAIT_1 STATE FIN has not been acked so - * enter the CLOSING state. - */ - case TCPS_FIN_WAIT_1: - tp->t_state = TCPS_CLOSING; - break; + /* + * Update MSS using recommendation from link status report. This is + * temporary + */ + tcp_update_mss_locked(so, ifp); - /* - * In FIN_WAIT_2 state enter the TIME_WAIT state, - * starting the time-wait timer, turning off the other - * standard timers. - */ - case TCPS_FIN_WAIT_2: - tp->t_state = TCPS_TIME_WAIT; - tcp_canceltimers(tp); - /* Shorten TIME_WAIT [RFC-1644, p.28] */ - if (tp->cc_recv != 0 && - tp->t_duration < TCPTV_MSL) { - tp->t_timer[TCPT_2MSL] = - tp->t_rxtcur * TCPTV_TWTRUNC; - /* For transaction client, force ACK now. */ - tp->t_flags |= TF_ACKNOW; - } - else - tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; +#if RTV_RPIPE + bufsize = rt->rt_rmx.rmx_recvpipe; + if (bufsize < so->so_rcv.sb_hiwat) +#endif + bufsize = so->so_rcv.sb_hiwat; + if (bufsize > mss) { + bufsize = (((bufsize + (u_int64_t)mss - 1) / (u_int64_t)mss) * (u_int64_t)mss); + if (bufsize > sb_max_corrected) { + bufsize = sb_max_corrected; + } + (void)sbreserve(&so->so_rcv, bufsize); + } - add_to_time_wait(tp); - soisdisconnected(so); - break; + set_tcp_stream_priority(so); + if (rt->rt_rmx.rmx_ssthresh) { /* - * In TIME_WAIT state restart the 2 MSL time_wait timer. + * There's some sort of gateway or interface + * buffer limit on the path. Use this to set + * slow-start threshold, but set the threshold to + * no less than 2*mss. */ - case TCPS_TIME_WAIT: - tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL; - add_to_time_wait(tp); - break; - } - } -#if TCPDEBUG - if (so->so_options & SO_DEBUG) { -#if INET6 - if (isipv6) - tcp_saveip._tcp_si6.ip6_plen = tilen; - else - tcp_saveip._tcp_si4.ip_len = tilen; -#else /* INET6 */ - tcp_saveip.ip_len = tilen; -#endif /* INET6 */ - - tcp_trace(TA_INPUT, ostate, tp, (void *)&tcp_saveip, - &tcp_savetcp, 0); + tp->snd_ssthresh = max(2 * mss, rt->rt_rmx.rmx_ssthresh); + tcpstat.tcps_usedssthresh++; + } else { + tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT; } -#endif /* - * Return any desired output. + * Set the slow-start flight size depending on whether this + * is a local network or not. */ - if (needoutput || (tp->t_flags & TF_ACKNOW)) - (void) tcp_output(tp); - if (need_sorwakeup) - sorwakeup(so); - if (need_sowwakeup) - sowwakeup(so); - KERNEL_DEBUG(DBG_FNC_TCP_INPUT | DBG_FUNC_END,0,0,0,0,0); - return; + if (CC_ALGO(tp)->cwnd_init != NULL) { + CC_ALGO(tp)->cwnd_init(tp); + } -dropafterack: - /* - * Generate an ACK dropping incoming segment if it occupies - * sequence space, where the ACK reflects our state. - * - * We can now skip the test for the RST flag since all - * paths to this code happen after packets containing - * RST have been dropped. - * - * In the SYN-RECEIVED state, don't send an ACK unless the - * segment we received passes the SYN-RECEIVED ACK test. - * If it fails send a RST. This breaks the loop in the - * "LAND" DoS attack, and also prevents an ACK storm - * between two listening ports that have been sent forged - * SYN segments, each with the source address of the other. - */ - if (tp->t_state == TCPS_SYN_RECEIVED && (thflags & TH_ACK) && - (SEQ_GT(tp->snd_una, th->th_ack) || - SEQ_GT(th->th_ack, tp->snd_max)) ) - goto dropwithreset; -#if TCPDEBUG - if (so->so_options & SO_DEBUG) { + tcp_ccdbg_trace(tp, NULL, TCP_CC_CWND_INIT); + + /* Route locked during lookup above */ + RT_UNLOCK(rt); +} + +/* + * Determine the MSS option to send on an outgoing SYN. + */ +int +tcp_mssopt(struct tcpcb *tp) +{ + struct rtentry *rt; + int mss; #if INET6 - if (isipv6) - tcp_saveip._tcp_si6.ip6_plen = tilen; - else - tcp_saveip._tcp_si4.ip_len = tilen; -#else /* INET6 */ - tcp_saveip.ip_len = tilen; -#endif /* INET6 */ - tcp_trace(TA_DROP, ostate, tp, (void *)&tcp_saveip, - &tcp_savetcp, 0); - } + int isipv6; + int min_protoh; #endif - m_freem(m); - tp->t_flags |= TF_ACKNOW; - (void) tcp_output(tp); - if (need_sorwakeup) - sorwakeup(so); - if (need_sowwakeup) - sowwakeup(so); - KERNEL_DEBUG(DBG_FNC_TCP_INPUT | DBG_FUNC_END,0,0,0,0,0); - return; -dropwithreset: - /* - * Generate a RST, dropping incoming segment. - * Make ACK acceptable to originator of segment. - * Don't bother to respond if destination was broadcast/multicast. - */ - if ((thflags & TH_RST) || m->m_flags & (M_BCAST|M_MCAST)) - goto drop; -#if INET6 - if (isipv6) { - if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) - goto drop; /* anycast check is done at the top */ - } else -#endif /* INET6 */ - if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr))) - goto drop; -#if TCPDEBUG - if (tp == 0 || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) { - if (tp == 0) { -#if INET6 - if (isipv6) - tcp_saveip._tcp_si6 = *ip6; - else - tcp_saveip._tcp_si4 = *ip; -#else /* INET6 */ - tcp_saveip = *ip; -#endif /* INET6 */ - } #if INET6 - if (isipv6) - tcp_saveip._tcp_si6.ip6_plen = tilen; - else - tcp_saveip._tcp_si4.ip_len = tilen; -#else /* INET6 */ - tcp_saveip.ip_len = tilen; -#endif /* INET6 */ - tcp_trace(TA_DROP, ostate, tp, (void *)&tcp_saveip, - &tcp_savetcp, 0); - } + isipv6 = ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) ? 1 : 0; + min_protoh = isipv6 ? sizeof(struct ip6_hdr) + sizeof(struct tcphdr) + : sizeof(struct tcpiphdr); +#else +#define min_protoh (sizeof (struct tcpiphdr)) #endif - if (thflags & TH_ACK) + #if INET6 - tcp_respond(tp, isipv6 ? (void *)ip6 : (void *)ip, th, m, - (tcp_seq)0, th->th_ack, TH_RST, isipv6); -#else /* INET6 */ - tcp_respond(tp, (void *)ip, th, m, - (tcp_seq)0, th->th_ack, TH_RST, isipv6); + if (isipv6) { + rt = tcp_rtlookup6(tp->t_inpcb, IFSCOPE_NONE); + } else #endif /* INET6 */ - else { - if (thflags & TH_SYN) - tilen++; + rt = tcp_rtlookup(tp->t_inpcb, IFSCOPE_NONE); + if (rt == NULL) { + return #if INET6 - tcp_respond(tp, isipv6 ? (void *)ip6 : (void *)ip, th, m, - th->th_seq+tilen, (tcp_seq)0, TH_RST|TH_ACK, - isipv6); -#else /* INET6 */ - tcp_respond(tp, (void *)ip, th, m, - th->th_seq+tilen, (tcp_seq)0, TH_RST|TH_ACK, - isipv6); + isipv6 ? tcp_v6mssdflt : #endif /* INET6 */ + tcp_mssdflt; } - /* destroy temporarily created socket */ - if (need_sorwakeup) - sorwakeup(so); - if (need_sowwakeup) - sowwakeup(so); - if (dropsocket) - (void) soabort(so); - KERNEL_DEBUG(DBG_FNC_TCP_INPUT | DBG_FUNC_END,0,0,0,0,0); - return; - -drop: /* - * Drop space held by incoming segment and return. + * Slower link window correction: + * If a value is specificied for slowlink_wsize use it for PPP links + * believed to be on a serial modem (speed <128Kbps). Excludes 9600bps as + * it is the default value adversized by pseudo-devices over ppp. */ -#if TCPDEBUG - if (tp == 0 || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) { - if (tp == 0) { -#if INET6 - if (isipv6) - tcp_saveip._tcp_si6 = *ip6; - else - tcp_saveip._tcp_si4 = *ip; -#else /* INET6 */ - tcp_saveip = *ip; -#endif /* INET6 */ - } -#if INET6 - if (isipv6) - tcp_saveip._tcp_si6.ip6_plen = tilen; - else - tcp_saveip._tcp_si4.ip_len = tilen; -#else /* INET6 */ - tcp_saveip.ip_len = tilen; -#endif /* INET6 */ - tcp_trace(TA_DROP, ostate, tp, (void *)&tcp_saveip, - &tcp_savetcp, 0); + if (rt->rt_ifp->if_type == IFT_PPP && slowlink_wsize > 0 && + rt->rt_ifp->if_baudrate > 9600 && rt->rt_ifp->if_baudrate <= 128000) { + tp->t_flags |= TF_SLOWLINK; } + +#if INET6 + mss = (isipv6 ? tcp_maxmtu6(rt) : tcp_maxmtu(rt)); +#else + mss = tcp_maxmtu(rt); #endif - m_freem(m); - if (need_sorwakeup) - sorwakeup(so); - if (need_sowwakeup) - sowwakeup(so); - /* destroy temporarily created socket */ - if (dropsocket) - (void) soabort(so); - KERNEL_DEBUG(DBG_FNC_TCP_INPUT | DBG_FUNC_END,0,0,0,0,0); - return; + /* Route locked during lookup above */ + RT_UNLOCK(rt); + +#if NECP + // At this point, the mss is just the MTU. Adjust if necessary. + mss = necp_socket_get_effective_mtu(tp->t_inpcb, mss); +#endif /* NECP */ + + return mss - min_protoh; } +/* + * On a partial ack arrives, force the retransmission of the + * next unacknowledged segment. Do not clear tp->t_dupacks. + * By setting snd_nxt to th_ack, this forces retransmission timer to + * be started again. + */ static void -tcp_dooptions(tp, cp, cnt, th, to) - struct tcpcb *tp; - u_char *cp; - int cnt; - struct tcphdr *th; - struct tcpopt *to; +tcp_newreno_partial_ack(struct tcpcb *tp, struct tcphdr *th) { - u_short mss = 0; - int opt, optlen; - - for (; cnt > 0; cnt -= optlen, cp += optlen) { - opt = cp[0]; - if (opt == TCPOPT_EOL) - break; - if (opt == TCPOPT_NOP) - optlen = 1; - else { - optlen = cp[1]; - if (optlen <= 0) - break; - } - switch (opt) { + tcp_seq onxt = tp->snd_nxt; + u_int32_t ocwnd = tp->snd_cwnd; + tp->t_timer[TCPT_REXMT] = 0; + tp->t_timer[TCPT_PTO] = 0; + tp->t_rtttime = 0; + tp->snd_nxt = th->th_ack; + /* + * Set snd_cwnd to one segment beyond acknowledged offset + * (tp->snd_una has not yet been updated when this function + * is called) + */ + tp->snd_cwnd = tp->t_maxseg + BYTES_ACKED(th, tp); + tp->t_flags |= TF_ACKNOW; + (void) tcp_output(tp); + tp->snd_cwnd = ocwnd; + if (SEQ_GT(onxt, tp->snd_nxt)) { + tp->snd_nxt = onxt; + } + /* + * Partial window deflation. Relies on fact that tp->snd_una + * not updated yet. + */ + if (tp->snd_cwnd > BYTES_ACKED(th, tp)) { + tp->snd_cwnd -= BYTES_ACKED(th, tp); + } else { + tp->snd_cwnd = 0; + } + tp->snd_cwnd += tp->t_maxseg; +} - default: - continue; +/* + * Drop a random TCP connection that hasn't been serviced yet and + * is eligible for discard. There is a one in qlen chance that + * we will return a null, saying that there are no dropable + * requests. In this case, the protocol specific code should drop + * the new request. This insures fairness. + * + * The listening TCP socket "head" must be locked + */ +static int +tcp_dropdropablreq(struct socket *head) +{ + struct socket *so, *sonext; + unsigned int i, j, qlen; + static u_int32_t rnd = 0; + static u_int64_t old_runtime; + static unsigned int cur_cnt, old_cnt; + u_int64_t now_sec; + struct inpcb *inp = NULL; + struct tcpcb *tp; - case TCPOPT_MAXSEG: - if (optlen != TCPOLEN_MAXSEG) - continue; - if (!(th->th_flags & TH_SYN)) - continue; - bcopy((char *) cp + 2, (char *) &mss, sizeof(mss)); - to->to_maxseg = ntohs(mss); - break; + if ((head->so_options & SO_ACCEPTCONN) == 0) { + return 0; + } - case TCPOPT_WINDOW: - if (optlen != TCPOLEN_WINDOW) - continue; - if (!(th->th_flags & TH_SYN)) - continue; - tp->t_flags |= TF_RCVD_SCALE; - tp->requested_s_scale = min(cp[2], TCP_MAX_WINSHIFT); - break; + if (TAILQ_EMPTY(&head->so_incomp)) { + return 0; + } - case TCPOPT_TIMESTAMP: - if (optlen != TCPOLEN_TIMESTAMP) - continue; - to->to_flag |= TOF_TS; - bcopy((char *)cp + 2, - (char *)&to->to_tsval, sizeof(to->to_tsval)); - NTOHL(to->to_tsval); - bcopy((char *)cp + 6, - (char *)&to->to_tsecr, sizeof(to->to_tsecr)); - NTOHL(to->to_tsecr); + so_acquire_accept_list(head, NULL); + socket_unlock(head, 0); + /* + * Check if there is any socket in the incomp queue + * that is closed because of a reset from the peer and is + * waiting to be garbage collected. If so, pick that as + * the victim + */ + TAILQ_FOREACH_SAFE(so, &head->so_incomp, so_list, sonext) { + inp = sotoinpcb(so); + tp = intotcpcb(inp); + if (tp != NULL && tp->t_state == TCPS_CLOSED && + so->so_head != NULL && + (so->so_state & (SS_INCOMP | SS_CANTSENDMORE | SS_CANTRCVMORE)) == + (SS_INCOMP | SS_CANTSENDMORE | SS_CANTRCVMORE)) { /* - * A timestamp received in a SYN makes - * it ok to send timestamp requests and replies. - */ - if (th->th_flags & TH_SYN) { - tp->t_flags |= TF_RCVD_TSTMP; - tp->ts_recent = to->to_tsval; - tp->ts_recent_age = tcp_now; - } - break; - case TCPOPT_CC: - if (optlen != TCPOLEN_CC) - continue; - to->to_flag |= TOF_CC; - bcopy((char *)cp + 2, - (char *)&to->to_cc, sizeof(to->to_cc)); - NTOHL(to->to_cc); - /* - * A CC or CC.new option received in a SYN makes - * it ok to send CC in subsequent segments. - */ - if (th->th_flags & TH_SYN) - tp->t_flags |= TF_RCVD_CC; - break; - case TCPOPT_CCNEW: - if (optlen != TCPOLEN_CC) - continue; - if (!(th->th_flags & TH_SYN)) - continue; - to->to_flag |= TOF_CCNEW; - bcopy((char *)cp + 2, - (char *)&to->to_cc, sizeof(to->to_cc)); - NTOHL(to->to_cc); - /* - * A CC or CC.new option received in a SYN makes - * it ok to send CC in subsequent segments. + * The listen socket is already locked but we + * can lock this socket here without lock ordering + * issues because it is in the incomp queue and + * is not visible to others. */ - tp->t_flags |= TF_RCVD_CC; - break; - case TCPOPT_CCECHO: - if (optlen != TCPOLEN_CC) - continue; - if (!(th->th_flags & TH_SYN)) + if (socket_try_lock(so)) { + so->so_usecount++; + goto found_victim; + } else { continue; - to->to_flag |= TOF_CCECHO; - bcopy((char *)cp + 2, - (char *)&to->to_ccecho, sizeof(to->to_ccecho)); - NTOHL(to->to_ccecho); - break; + } } } -} -/* - * Pull out of band byte out of a segment so - * it doesn't appear in the user's data queue. - * It is still reflected in the segment length for - * sequencing purposes. - */ -static void -tcp_pulloutofband(so, th, m) - struct socket *so; - struct tcphdr *th; - register struct mbuf *m; -{ - int cnt = th->th_urp - 1; + so = TAILQ_FIRST(&head->so_incomp); - while (cnt >= 0) { - if (m->m_len > cnt) { - char *cp = mtod(m, caddr_t) + cnt; - struct tcpcb *tp = sototcpcb(so); + now_sec = net_uptime(); + if ((i = (now_sec - old_runtime)) != 0) { + old_runtime = now_sec; + old_cnt = cur_cnt / i; + cur_cnt = 0; + } - tp->t_iobc = *cp; - tp->t_oobflags |= TCPOOB_HAVEDATA; - bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); - m->m_len--; - return; + qlen = head->so_incqlen; + if (rnd == 0) { + rnd = RandomULong(); + } + + if (++cur_cnt > qlen || old_cnt > qlen) { + rnd = (314159 * rnd + 66329) & 0xffff; + j = ((qlen + 1) * rnd) >> 16; + + while (j-- && so) { + so = TAILQ_NEXT(so, so_list); } - cnt -= m->m_len; - m = m->m_next; - if (m == 0) - break; } - panic("tcp_pulloutofband"); -} + /* Find a connection that is not already closing (or being served) */ + while (so) { + inp = (struct inpcb *)so->so_pcb; -/* - * Collect new round-trip time estimate - * and update averages and current timeout. - */ -static void -tcp_xmit_timer(tp, rtt) - register struct tcpcb *tp; - short rtt; -{ - register int delta; + sonext = TAILQ_NEXT(so, so_list); - tcpstat.tcps_rttupdated++; - tp->t_rttupdated++; - if (tp->t_srtt != 0) { - /* - * srtt is stored as fixed point with 5 bits after the - * binary point (i.e., scaled by 8). The following magic - * is equivalent to the smoothing algorithm in rfc793 with - * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed - * point). Adjust rtt to origin 0. - */ - delta = ((rtt - 1) << TCP_DELTA_SHIFT) - - (tp->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT)); + if (in_pcb_checkstate(inp, WNT_ACQUIRE, 0) != WNT_STOPUSING) { + /* + * Avoid the issue of a socket being accepted + * by one input thread and being dropped by + * another input thread. If we can't get a hold + * on this mutex, then grab the next socket in + * line. + */ + if (socket_try_lock(so)) { + so->so_usecount++; + if ((so->so_usecount == 2) && + (so->so_state & SS_INCOMP) && + !(so->so_flags & SOF_INCOMP_INPROGRESS)) { + break; + } else { + /* + * don't use if being accepted or + * used in any other way + */ + in_pcb_checkstate(inp, WNT_RELEASE, 1); + socket_unlock(so, 1); + } + } else { + /* + * do not try to lock the inp in + * in_pcb_checkstate because the lock + * is already held in some other thread. + * Only drop the inp_wntcnt reference. + */ + in_pcb_checkstate(inp, WNT_RELEASE, 1); + } + } + so = sonext; + } + if (so == NULL) { + socket_lock(head, 0); + so_release_accept_list(head); + return 0; + } - if ((tp->t_srtt += delta) <= 0) - tp->t_srtt = 1; + /* Makes sure socket is still in the right state to be discarded */ + + if (in_pcb_checkstate(inp, WNT_RELEASE, 1) == WNT_STOPUSING) { + socket_unlock(so, 1); + socket_lock(head, 0); + so_release_accept_list(head); + return 0; + } + +found_victim: + if (so->so_usecount != 2 || !(so->so_state & SS_INCOMP)) { + /* do not discard: that socket is being accepted */ + socket_unlock(so, 1); + socket_lock(head, 0); + so_release_accept_list(head); + return 0; + } + socket_lock(head, 0); + TAILQ_REMOVE(&head->so_incomp, so, so_list); + head->so_incqlen--; + head->so_qlen--; + so->so_state &= ~SS_INCOMP; + so->so_flags |= SOF_OVERFLOW; + so->so_head = NULL; + so_release_accept_list(head); + socket_unlock(head, 0); + + socket_lock_assert_owned(so); + tp = sototcpcb(so); + + tcp_close(tp); + if (inp->inp_wantcnt > 0 && inp->inp_wantcnt != WNT_STOPUSING) { /* - * We accumulate a smoothed rtt variance (actually, a - * smoothed mean difference), then set the retransmit - * timer to smoothed rtt + 4 times the smoothed variance. - * rttvar is stored as fixed point with 4 bits after the - * binary point (scaled by 16). The following is - * equivalent to rfc793 smoothing with an alpha of .75 - * (rttvar = rttvar*3/4 + |delta| / 4). This replaces - * rfc793's wired-in beta. + * Some one has a wantcnt on this pcb. Since WNT_ACQUIRE + * doesn't require a lock, it could have happened while + * we are holding the lock. This pcb will have to + * be garbage collected later. + * Release the reference held for so_incomp queue */ - if (delta < 0) - delta = -delta; - delta -= tp->t_rttvar >> (TCP_RTTVAR_SHIFT - TCP_DELTA_SHIFT); - if ((tp->t_rttvar += delta) <= 0) - tp->t_rttvar = 1; + VERIFY(so->so_usecount > 0); + so->so_usecount--; + socket_unlock(so, 1); + } else { + /* + * Unlock this socket and leave the reference on. + * We need to acquire the pcbinfo lock in order to + * fully dispose it off + */ + socket_unlock(so, 0); + + lck_rw_lock_exclusive(tcbinfo.ipi_lock); + + socket_lock(so, 0); + /* Release the reference held for so_incomp queue */ + VERIFY(so->so_usecount > 0); + so->so_usecount--; + + if (so->so_usecount != 1 || + (inp->inp_wantcnt > 0 && + inp->inp_wantcnt != WNT_STOPUSING)) { + /* + * There is an extra wantcount or usecount + * that must have been added when the socket + * was unlocked. This socket will have to be + * garbage collected later + */ + socket_unlock(so, 1); + } else { + /* Drop the reference held for this function */ + VERIFY(so->so_usecount > 0); + so->so_usecount--; + + in_pcbdispose(inp); + } + lck_rw_done(tcbinfo.ipi_lock); + } + tcpstat.tcps_drops++; + + socket_lock(head, 0); + return 1; +} + +/* Set background congestion control on a socket */ +void +tcp_set_background_cc(struct socket *so) +{ + tcp_set_new_cc(so, TCP_CC_ALGO_BACKGROUND_INDEX); +} + +/* Set foreground congestion control on a socket */ +void +tcp_set_foreground_cc(struct socket *so) +{ + if (tcp_use_newreno) { + tcp_set_new_cc(so, TCP_CC_ALGO_NEWRENO_INDEX); } else { - /* - * No rtt measurement yet - use the unsmoothed rtt. - * Set the variance to half the rtt (so our first - * retransmit happens at 3*rtt). - */ - tp->t_srtt = rtt << TCP_RTT_SHIFT; - tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1); + tcp_set_new_cc(so, TCP_CC_ALGO_CUBIC_INDEX); } - tp->t_rtt = 0; - tp->t_rxtshift = 0; +} - /* - * the retransmit should happen at rtt + 4 * rttvar. - * Because of the way we do the smoothing, srtt and rttvar - * will each average +1/2 tick of bias. When we compute - * the retransmit timer, we want 1/2 tick of rounding and - * 1 extra tick because of +-1/2 tick uncertainty in the - * firing of the timer. The bias will give us exactly the - * 1.5 tick we need. But, because the bias is - * statistical, we have to test that we don't drop below - * the minimum feasible timer (which is 2 ticks). - */ - TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), - max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX); +static void +tcp_set_new_cc(struct socket *so, uint16_t cc_index) +{ + struct inpcb *inp = sotoinpcb(so); + struct tcpcb *tp = intotcpcb(inp); + u_char old_cc_index = 0; + if (tp->tcp_cc_index != cc_index) { + old_cc_index = tp->tcp_cc_index; + + if (CC_ALGO(tp)->cleanup != NULL) { + CC_ALGO(tp)->cleanup(tp); + } + tp->tcp_cc_index = cc_index; - /* - * We received an ack for a packet that wasn't retransmitted; - * it is probably safe to discard any error indications we've - * received recently. This isn't quite right, but close enough - * for now (a route might have failed after we sent a segment, - * and the return path might not be symmetrical). - */ - tp->t_softerror = 0; + tcp_cc_allocate_state(tp); + + if (CC_ALGO(tp)->switch_to != NULL) { + CC_ALGO(tp)->switch_to(tp, old_cc_index); + } + + tcp_ccdbg_trace(tp, NULL, TCP_CC_CHANGE_ALGO); + } } -/* - * Determine a reasonable value for maxseg size. - * If the route is known, check route for mtu. - * If none, use an mss that can be handled on the outgoing - * interface without forcing IP to fragment; if bigger than - * an mbuf cluster (MCLBYTES), round down to nearest multiple of MCLBYTES - * to utilize large mbufs. If no route is found, route has no mtu, - * or the destination isn't local, use a default, hopefully conservative - * size (usually 512 or the default IP max size, but no more than the mtu - * of the interface), as we can't discover anything about intervening - * gateways or networks. We also initialize the congestion/slow start - * window to be a single segment if the destination isn't local. - * While looking at the routing entry, we also initialize other path-dependent - * parameters from pre-set or cached values in the routing entry. - * - * Also take into account the space needed for options that we - * send regularly. Make maxseg shorter by that amount to assure - * that we can send maxseg amount of data even when the options - * are present. Store the upper limit of the length of options plus - * data in maxopd. - * - * NOTE that this routine is only called when we process an incoming - * segment, for outgoing segments only tcp_mssopt is called. - * - * In case of T/TCP, we call this routine during implicit connection - * setup as well (offer = -1), to initialize maxseg from the cached - * MSS of our peer. - */ void -tcp_mss(tp, offer, isipv6) - struct tcpcb *tp; - int offer; -#if INET6 - int isipv6; -#endif +tcp_set_recv_bg(struct socket *so) { - register struct rtentry *rt; - struct ifnet *ifp; - register int rtt, mss; - u_long bufsize; - struct inpcb *inp; - struct socket *so; - struct rmxp_tao *taop; - int origoffer = offer; -#if INET6 - int lgminh = isipv6 ? sizeof (struct tcpip6hdr) : - sizeof (struct tcpiphdr); -#else /* INET6 */ -#define lgminh (sizeof (struct tcpiphdr)) -#endif /* INET6 */ + if (!IS_TCP_RECV_BG(so)) { + so->so_flags1 |= SOF1_TRAFFIC_MGT_TCP_RECVBG; + } - inp = tp->t_inpcb; -#if INET6 - if (isipv6) - rt = tcp_rtlookup6(inp); - else -#endif /* INET6 */ - rt = tcp_rtlookup(inp); - if (rt == NULL) { - tp->t_maxopd = tp->t_maxseg = -#if INET6 - isipv6 ? tcp_v6mssdflt : -#endif /* INET6 */ - tcp_mssdflt; - return; + /* Unset Large Receive Offload on background sockets */ + so_set_lro(so, SO_TC_BK); +} + +void +tcp_clear_recv_bg(struct socket *so) +{ + if (IS_TCP_RECV_BG(so)) { + so->so_flags1 &= ~(SOF1_TRAFFIC_MGT_TCP_RECVBG); } - ifp = rt->rt_ifp; - so = inp->inp_socket; - taop = rmx_taop(rt->rt_rmx); - /* - * Offer == -1 means that we didn't receive SYN yet, - * use cached value in that case; - */ - if (offer == -1) - offer = taop->tao_mssopt; /* - * Offer == 0 means that there was no MSS on the SYN segment, - * in this case we use tcp_mssdflt. + * Set/unset use of Large Receive Offload depending on + * the traffic class */ - if (offer == 0) - offer = -#if INET6 - isipv6 ? tcp_v6mssdflt : -#endif /* INET6 */ - tcp_mssdflt; - else - /* - * Sanity check: make sure that maxopd will be large - * enough to allow some data on segments even is the - * all the option space is used (40bytes). Otherwise - * funny things may happen in tcp_output. - */ - offer = max(offer, 64); - taop->tao_mssopt = offer; + so_set_lro(so, so->so_traffic_class); +} +void +inp_fc_unthrottle_tcp(struct inpcb *inp) +{ + struct tcpcb *tp = inp->inp_ppcb; /* - * While we're here, check if there's an initial rtt - * or rttvar. Convert from the route-table units - * to scaled multiples of the slow timeout timer. + * Back off the slow-start threshold and enter + * congestion avoidance phase */ - if (tp->t_srtt == 0 && (rtt = rt->rt_rmx.rmx_rtt)) { - /* - * XXX the lock bit for RTT indicates that the value - * is also a minimum value; this is subject to time. - */ - if (rt->rt_rmx.rmx_locks & RTV_RTT) - tp->t_rttmin = rtt / (RTM_RTTUNIT / PR_SLOWHZ); - tp->t_srtt = rtt / (RTM_RTTUNIT / (PR_SLOWHZ * TCP_RTT_SCALE)); - tcpstat.tcps_usedrtt++; - if (rt->rt_rmx.rmx_rttvar) { - tp->t_rttvar = rt->rt_rmx.rmx_rttvar / - (RTM_RTTUNIT / (PR_SLOWHZ * TCP_RTTVAR_SCALE)); - tcpstat.tcps_usedrttvar++; - } else { - /* default variation is +- 1 rtt */ - tp->t_rttvar = - tp->t_srtt * TCP_RTTVAR_SCALE / TCP_RTT_SCALE; - } - TCPT_RANGESET(tp->t_rxtcur, - ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1, - tp->t_rttmin, TCPTV_REXMTMAX); + if (CC_ALGO(tp)->pre_fr != NULL) { + CC_ALGO(tp)->pre_fr(tp); } - /* - * if there's an mtu associated with the route, use it - * else, use the link mtu. - */ - if (rt->rt_rmx.rmx_mtu) - mss = rt->rt_rmx.rmx_mtu - lgminh; - else - mss = -#if INET6 - isipv6 ? nd_ifinfo[rt->rt_ifp->if_index].linkmtu : -#endif - ifp->if_mtu - lgminh; - if (rt->rt_rmx.rmx_mtu == 0) { -#if INET6 - if (isipv6) { - if (!in6_localaddr(&inp->in6p_faddr)) - mss = min(mss, tcp_v6mssdflt); - } else -#endif /* INET6 */ - if (!in_localaddr(inp->inp_faddr)) - mss = min(mss, tcp_mssdflt); - } - mss = min(mss, offer); + tp->snd_cwnd = tp->snd_ssthresh; + tp->t_flagsext &= ~TF_CWND_NONVALIDATED; /* - * maxopd stores the maximum length of data AND options - * in a segment; maxseg is the amount of data in a normal - * segment. We need to store this value (maxopd) apart - * from maxseg, because now every segment carries options - * and thus we normally have somewhat less data in segments. + * Restart counting for ABC as we changed the + * congestion window just now. */ - tp->t_maxopd = mss; + tp->t_bytes_acked = 0; - /* - * In case of T/TCP, origoffer==-1 indicates, that no segments - * were received yet. In this case we just guess, otherwise - * we do the same as before T/TCP. + /* Reset retransmit shift as we know that the reason + * for delay in sending a packet is due to flow + * control on the outgoing interface. There is no need + * to backoff retransmit timer. */ - if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP && - (origoffer == -1 || - (tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP)) - mss -= TCPOLEN_TSTAMP_APPA; - if ((tp->t_flags & (TF_REQ_CC|TF_NOOPT)) == TF_REQ_CC && - (origoffer == -1 || - (tp->t_flags & TF_RCVD_CC) == TF_RCVD_CC)) - mss -= TCPOLEN_CC_APPA; + TCP_RESET_REXMT_STATE(tp); -#if (MCLBYTES & (MCLBYTES - 1)) == 0 - if (mss > MCLBYTES) - mss &= ~(MCLBYTES-1); -#else - if (mss > MCLBYTES) - mss = mss / MCLBYTES * MCLBYTES; -#endif /* - * If there's a pipesize, change the socket buffer - * to that size. Make the socket buffers an integral - * number of mss units; if the mss is larger than - * the socket buffer, decrease the mss. + * Start the output stream again. Since we are + * not retransmitting data, do not reset the + * retransmit timer or rtt calculation. */ -#if RTV_SPIPE - if ((bufsize = rt->rt_rmx.rmx_sendpipe) == 0) -#endif - bufsize = so->so_snd.sb_hiwat; - if (bufsize < mss) - mss = bufsize; - else { - bufsize = roundup(bufsize, mss); - if (bufsize > sb_max) - bufsize = sb_max; - (void)sbreserve(&so->so_snd, bufsize); - } - tp->t_maxseg = mss; + tcp_output(tp); +} -#if RTV_RPIPE - if ((bufsize = rt->rt_rmx.rmx_recvpipe) == 0) -#endif - bufsize = so->so_rcv.sb_hiwat; - if (bufsize > mss) { - bufsize = roundup(bufsize, mss); - if (bufsize > sb_max) - bufsize = sb_max; - (void)sbreserve(&so->so_rcv, bufsize); +static int +tcp_getstat SYSCTL_HANDLER_ARGS +{ +#pragma unused(oidp, arg1, arg2) + + int error; + struct tcpstat *stat; + stat = &tcpstat; +#if !CONFIG_EMBEDDED + struct tcpstat zero_stat; + + if (tcp_disable_access_to_stats && + !kauth_cred_issuser(kauth_cred_get())) { + bzero(&zero_stat, sizeof(zero_stat)); + stat = &zero_stat; } - /* - * Don't force slow-start on local network. - */ -#if INET6 - if (isipv6) { - if (!in6_localaddr(&inp->in6p_faddr)) - tp->snd_cwnd = mss; - } else -#endif /* INET6 */ - if (!in_localaddr(inp->inp_faddr)) - tp->snd_cwnd = mss; - if (rt->rt_rmx.rmx_ssthresh) { - /* - * There's some sort of gateway or interface - * buffer limit on the path. Use this to set - * the slow start threshhold, but set the - * threshold to no less than 2*mss. - */ - tp->snd_ssthresh = max(2 * mss, rt->rt_rmx.rmx_ssthresh); - tcpstat.tcps_usedssthresh++; +#endif /* !CONFIG_EMBEDDED */ + + if (req->oldptr == 0) { + req->oldlen = (size_t)sizeof(struct tcpstat); } + + error = SYSCTL_OUT(req, stat, MIN(sizeof(tcpstat), req->oldlen)); + + return error; } /* - * Determine the MSS option to send on an outgoing SYN. + * Checksum extended TCP header and data. */ int -tcp_mssopt(tp, isipv6) - struct tcpcb *tp; -#if INET6 - int isipv6; -#endif +tcp_input_checksum(int af, struct mbuf *m, struct tcphdr *th, int off, int tlen) { - struct rtentry *rt; - int mss; -#if INET6 - int lgminh = isipv6 ? sizeof (struct tcpip6hdr) : - sizeof (struct tcpiphdr); -#else /* INET6 */ -#define lgminh (sizeof (struct tcpiphdr)) -#endif /* INET6 */ + struct ifnet *ifp = m->m_pkthdr.rcvif; + switch (af) { + case AF_INET: { + struct ip *ip = mtod(m, struct ip *); + struct ipovly *ipov = (struct ipovly *)ip; + + if (m->m_pkthdr.pkt_flags & PKTF_SW_LRO_DID_CSUM) { + return 0; + } + + /* ip_stripoptions() must have been called before we get here */ + ASSERT((ip->ip_hl << 2) == sizeof(*ip)); + + if ((hwcksum_rx || (ifp->if_flags & IFF_LOOPBACK) || + (m->m_pkthdr.pkt_flags & PKTF_LOOP)) && + (m->m_pkthdr.csum_flags & CSUM_DATA_VALID)) { + if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) { + th->th_sum = m->m_pkthdr.csum_rx_val; + } else { + uint32_t sum = m->m_pkthdr.csum_rx_val; + uint32_t start = m->m_pkthdr.csum_rx_start; + int32_t trailer = (m_pktlen(m) - (off + tlen)); + + /* + * Perform 1's complement adjustment of octets + * that got included/excluded in the hardware- + * calculated checksum value. Ignore cases + * where the value already includes the entire + * IP header span, as the sum for those octets + * would already be 0 by the time we get here; + * IP has already performed its header checksum + * checks. If we do need to adjust, restore + * the original fields in the IP header when + * computing the adjustment value. Also take + * care of any trailing bytes and subtract out + * their partial sum. + */ + ASSERT(trailer >= 0); + if ((m->m_pkthdr.csum_flags & CSUM_PARTIAL) && + ((start != 0 && start != off) || trailer)) { + uint32_t swbytes = (uint32_t)trailer; + + if (start < off) { + ip->ip_len += sizeof(*ip); +#if BYTE_ORDER != BIG_ENDIAN + HTONS(ip->ip_len); + HTONS(ip->ip_off); +#endif /* BYTE_ORDER != BIG_ENDIAN */ + } + /* callee folds in sum */ + sum = m_adj_sum16(m, start, off, + tlen, sum); + if (off > start) { + swbytes += (off - start); + } else { + swbytes += (start - off); + } + + if (start < off) { +#if BYTE_ORDER != BIG_ENDIAN + NTOHS(ip->ip_off); + NTOHS(ip->ip_len); +#endif /* BYTE_ORDER != BIG_ENDIAN */ + ip->ip_len -= sizeof(*ip); + } + + if (swbytes != 0) { + tcp_in_cksum_stats(swbytes); + } + if (trailer != 0) { + m_adj(m, -trailer); + } + } + + /* callee folds in sum */ + th->th_sum = in_pseudo(ip->ip_src.s_addr, + ip->ip_dst.s_addr, + sum + htonl(tlen + IPPROTO_TCP)); + } + th->th_sum ^= 0xffff; + } else { + uint16_t ip_sum; + int len; + char b[9]; + + bcopy(ipov->ih_x1, b, sizeof(ipov->ih_x1)); + bzero(ipov->ih_x1, sizeof(ipov->ih_x1)); + ip_sum = ipov->ih_len; + ipov->ih_len = (u_short)tlen; +#if BYTE_ORDER != BIG_ENDIAN + HTONS(ipov->ih_len); +#endif + len = sizeof(struct ip) + tlen; + th->th_sum = in_cksum(m, len); + bcopy(b, ipov->ih_x1, sizeof(ipov->ih_x1)); + ipov->ih_len = ip_sum; + + tcp_in_cksum_stats(len); + } + break; + } #if INET6 - if (isipv6) - rt = tcp_rtlookup6(tp->t_inpcb); - else -#endif /* INET6 */ - rt = tcp_rtlookup(tp->t_inpcb); - if (rt == NULL) - return -#if INET6 - isipv6 ? tcp_v6mssdflt : + case AF_INET6: { + struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *); + + if (m->m_pkthdr.pkt_flags & PKTF_SW_LRO_DID_CSUM) { + return 0; + } + + if ((hwcksum_rx || (ifp->if_flags & IFF_LOOPBACK) || + (m->m_pkthdr.pkt_flags & PKTF_LOOP)) && + (m->m_pkthdr.csum_flags & CSUM_DATA_VALID)) { + if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) { + th->th_sum = m->m_pkthdr.csum_rx_val; + } else { + uint32_t sum = m->m_pkthdr.csum_rx_val; + uint32_t start = m->m_pkthdr.csum_rx_start; + int32_t trailer = (m_pktlen(m) - (off + tlen)); + + /* + * Perform 1's complement adjustment of octets + * that got included/excluded in the hardware- + * calculated checksum value. Also take care + * of any trailing bytes and subtract out their + * partial sum. + */ + ASSERT(trailer >= 0); + if ((m->m_pkthdr.csum_flags & CSUM_PARTIAL) && + (start != off || trailer != 0)) { + uint16_t s = 0, d = 0; + uint32_t swbytes = (uint32_t)trailer; + + if (IN6_IS_SCOPE_EMBED(&ip6->ip6_src)) { + s = ip6->ip6_src.s6_addr16[1]; + ip6->ip6_src.s6_addr16[1] = 0; + } + if (IN6_IS_SCOPE_EMBED(&ip6->ip6_dst)) { + d = ip6->ip6_dst.s6_addr16[1]; + ip6->ip6_dst.s6_addr16[1] = 0; + } + + /* callee folds in sum */ + sum = m_adj_sum16(m, start, off, + tlen, sum); + if (off > start) { + swbytes += (off - start); + } else { + swbytes += (start - off); + } + + if (IN6_IS_SCOPE_EMBED(&ip6->ip6_src)) { + ip6->ip6_src.s6_addr16[1] = s; + } + if (IN6_IS_SCOPE_EMBED(&ip6->ip6_dst)) { + ip6->ip6_dst.s6_addr16[1] = d; + } + + if (swbytes != 0) { + tcp_in6_cksum_stats(swbytes); + } + if (trailer != 0) { + m_adj(m, -trailer); + } + } + + th->th_sum = in6_pseudo( + &ip6->ip6_src, &ip6->ip6_dst, + sum + htonl(tlen + IPPROTO_TCP)); + } + th->th_sum ^= 0xffff; + } else { + tcp_in6_cksum_stats(tlen); + th->th_sum = in6_cksum(m, IPPROTO_TCP, off, tlen); + } + break; + } #endif /* INET6 */ - tcp_mssdflt; + default: + VERIFY(0); + /* NOTREACHED */ + } + + if (th->th_sum != 0) { + tcpstat.tcps_rcvbadsum++; + IF_TCP_STATINC(ifp, badformat); + return -1; + } + + return 0; +} + + +SYSCTL_PROC(_net_inet_tcp, TCPCTL_STATS, stats, + CTLTYPE_STRUCT | CTLFLAG_RD | CTLFLAG_LOCKED, 0, 0, tcp_getstat, + "S,tcpstat", "TCP statistics (struct tcpstat, netinet/tcp_var.h)"); + +static int +sysctl_rexmtthresh SYSCTL_HANDLER_ARGS +{ +#pragma unused(arg1, arg2) + + int error, val = tcprexmtthresh; - mss = rt->rt_ifp->if_mtu - lgminh; + error = sysctl_handle_int(oidp, &val, 0, req); + if (error || !req->newptr) { + return error; + } + + /* + * Constrain the number of duplicate ACKs + * to consider for TCP fast retransmit + * to either 2 or 3 + */ - return mss; + if (val < 2 || val > 3) { + return EINVAL; + } + + tcprexmtthresh = val; + + return 0; } + +SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmt_thresh, CTLTYPE_INT | CTLFLAG_RW | + CTLFLAG_LOCKED, &tcprexmtthresh, 0, &sysctl_rexmtthresh, "I", + "Duplicate ACK Threshold for Fast Retransmit");