X-Git-Url: https://git.saurik.com/apple/xnu.git/blobdiff_plain/de355530ae67247cbd0da700edb3a2a1dae884c2..060df5ea7c632b1ac8cc8aac1fb59758165c2084:/bsd/netinet/tcp_input.c diff --git a/bsd/netinet/tcp_input.c b/bsd/netinet/tcp_input.c index eb294a6a2..b65e9d5c6 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) 2000-2008 Apple Inc. All rights reserved. * - * @APPLE_LICENSE_HEADER_START@ + * @APPLE_OSREFERENCE_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 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. * - * This Original Code and all software distributed under the License are - * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER + * 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. + * 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_LICENSE_HEADER_END@ + * @APPLE_OSREFERENCE_LICENSE_HEADER_END@ */ /* * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995 @@ -54,7 +60,12 @@ * @(#)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. + */ #include #include @@ -70,7 +81,10 @@ #include /* before tcp_seq.h, for tcp_random18() */ +#include + #include +#include #include #include @@ -111,6 +125,10 @@ struct tcphdr tcp_savetcp; #include #endif /*IPSEC*/ +#if CONFIG_MACF_NET || CONFIG_MACF_SOCKET +#include +#endif /* CONFIG_MACF_NET || CONFIG_MACF_SOCKET */ + #include #ifndef __APPLE__ @@ -122,17 +140,14 @@ MALLOC_DEFINE(M_TSEGQ, "tseg_qent", "TCP segment queue entry"); #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; +static int tcprexmtthresh = 2; tcp_cc tcp_ccgen; -extern int apple_hwcksum_rx; #if IPSEC extern int ipsec_bypass; #endif struct tcpstat tcpstat; -SYSCTL_STRUCT(_net_inet_tcp, TCPCTL_STATS, stats, CTLFLAG_RD, - &tcpstat , tcpstat, "TCP statistics (struct tcpstat, netinet/tcp_var.h)"); static int log_in_vain = 0; SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_in_vain, CTLFLAG_RW, @@ -142,7 +157,7 @@ static int blackhole = 0; SYSCTL_INT(_net_inet_tcp, OID_AUTO, blackhole, CTLFLAG_RW, &blackhole, 0, "Do not send RST when dropping refused connections"); -int tcp_delack_enabled = 1; +int tcp_delack_enabled = 3; SYSCTL_INT(_net_inet_tcp, OID_AUTO, delayed_ack, CTLFLAG_RW, &tcp_delack_enabled, 0, "Delay ACK to try and piggyback it onto a data packet"); @@ -153,24 +168,71 @@ SYSCTL_INT(_net_inet_tcp, OID_AUTO, tcp_lq_overflow, CTLFLAG_RW, "Listen Queue Overflow"); #if TCP_DROP_SYNFIN -static int drop_synfin = 0; +static int drop_synfin = 1; SYSCTL_INT(_net_inet_tcp, OID_AUTO, drop_synfin, CTLFLAG_RW, &drop_synfin, 0, "Drop TCP packets with SYN+FIN set"); #endif -u_long tcp_now; +SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass, CTLFLAG_RW|CTLFLAG_LOCKED, 0, + "TCP Segment Reassembly Queue"); + +__private_extern__ int tcp_reass_maxseg = 0; +SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RW, + &tcp_reass_maxseg, 0, + "Global maximum number of TCP Segments in Reassembly Queue"); + +__private_extern__ int tcp_reass_qsize = 0; +SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, cursegments, CTLFLAG_RD, + &tcp_reass_qsize, 0, + "Global number of TCP Segments currently in Reassembly Queue"); + +static int tcp_reass_overflows = 0; +SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, overflows, CTLFLAG_RD, + &tcp_reass_overflows, 0, + "Global number of TCP Segment Reassembly Queue Overflows"); + + +__private_extern__ int slowlink_wsize = 8192; +SYSCTL_INT(_net_inet_tcp, OID_AUTO, slowlink_wsize, CTLFLAG_RW, + &slowlink_wsize, 0, "Maximum advertised window size for slowlink"); + +static int maxseg_unacked = 8; +SYSCTL_INT(_net_inet_tcp, OID_AUTO, maxseg_unacked, CTLFLAG_RW, + &maxseg_unacked, 0, "Maximum number of outstanding segments left unacked"); + +static int tcp_do_rfc3465 = 1; +SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3465, CTLFLAG_RW, + &tcp_do_rfc3465, 0, ""); + +static int tcp_do_rfc3465_lim2 = 1; +SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3465_lim2, CTLFLAG_RW, + &tcp_do_rfc3465_lim2, 0, "Appropriate bytes counting w/ L=2*SMSS"); + +#if CONFIG_IFEF_NOWINDOWSCALE +int tcp_obey_ifef_nowindowscale = 0; +SYSCTL_INT(_net_inet_tcp, OID_AUTO, obey_ifef_nowindowscale, CTLFLAG_RW, + &tcp_obey_ifef_nowindowscale, 0, ""); +#endif + +extern int tcp_TCPTV_MIN; + +u_int32_t tcp_now; + struct inpcbhead tcb; #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 *, int)); -static int tcp_reass __P((struct tcpcb *, struct tcphdr *, int *, - struct mbuf *)); -static void tcp_xmit_timer __P((struct tcpcb *, int)); -static int tcp_newreno __P((struct tcpcb *, struct tcphdr *)); +static void tcp_dooptions(struct tcpcb *, + u_char *, int, struct tcphdr *, struct tcpopt *, unsigned int); +static void tcp_pulloutofband(struct socket *, + struct tcphdr *, struct mbuf *, int); +static int tcp_reass(struct tcpcb *, struct tcphdr *, int *, + struct mbuf *); +static void tcp_xmit_timer(struct tcpcb *, int); +static inline unsigned int tcp_maxmtu(struct rtentry *); +#if INET6 +static inline unsigned int tcp_maxmtu6(struct rtentry *); +#endif /* Neighbor Discovery, Neighbor Unreachability Detection Upper layer hint. */ #if INET6 @@ -185,18 +247,58 @@ do { \ #define ND6_HINT(tp) #endif -extern u_long *delack_bitmask; +extern u_int32_t *delack_bitmask; + +extern void add_to_time_wait(struct tcpcb *); +extern void postevent(struct socket *, struct sockbuf *, int); + +extern void ipfwsyslog( int level, const char *format,...); +extern int ChkAddressOK( __uint32_t dstaddr, __uint32_t srcaddr ); +extern int fw_verbose; +__private_extern__ int tcp_sockthreshold; +__private_extern__ int tcp_win_scale; + +#if IPFIREWALL +#define log_in_vain_log( a ) { \ + if ( (log_in_vain == 3 ) && (fw_verbose == 2)) { /* Apple logging, log to ipfw.log */ \ + ipfwsyslog a ; \ + } \ + else log a ; \ +} +#else +#define log_in_vain_log( a ) { log a; } +#endif + /* - * Indicate whether this ack should be delayed. We can delay the ack if - * - delayed acks are enabled and - * - there is no delayed ack timer in progress and + * Indicate whether this ack should be delayed. + * We can delay the ack if: + * - delayed acks are enabled (set to 1) and * - our last ack wasn't a 0-sized window. We never want to delay - * the ack that opens up a 0-sized window. + * the ack that opens up a 0-sized window. + * - delayed acks are enabled (set to 2, "more compatible") and + * - our last ack wasn't a 0-sized window. + * - if the peer hasn't sent us a TH_PUSH data packet (this solves 3649245) + * - the peer hasn't sent us a TH_PUSH data packet, if he did, take this as a clue that we + * need to ACK with no delay. This helps higher level protocols who won't send + * us more data even if the window is open because their last "segment" hasn't been ACKed + * - delayed acks are enabled (set to 3, "streaming detection") and + * - if we receive more than "maxseg_unacked" full packets per second on this socket + * - if we don't have more than "maxseg_unacked" delayed so far + * - if those criteria aren't met, acts like "2". Allowing faster acking while browsing for example. + * */ #define DELAY_ACK(tp) \ - (tcp_delack_enabled && !callout_pending(tp->tt_delack) && \ - (tp->t_flags & TF_RXWIN0SENT) == 0) + (((tcp_delack_enabled == 1) && ((tp->t_flags & TF_RXWIN0SENT) == 0)) || \ + (((tcp_delack_enabled == 2) && (tp->t_flags & TF_RXWIN0SENT) == 0) && \ + ((thflags & TH_PUSH) == 0) && ((tp->t_flags & TF_DELACK) == 0)) || \ + (((tcp_delack_enabled == 3) && (tp->t_flags & TF_RXWIN0SENT) == 0) && \ + (tp->t_rcvtime == 0) && ((thflags & TH_PUSH) == 0) && \ + (((tp->t_unacksegs == 0)) || \ + ((tp->rcv_byps > (maxseg_unacked * tp->t_maxseg)) && (tp->t_unacksegs < maxseg_unacked))))) + +static int tcp_dropdropablreq(struct socket *head); +static void tcp_newreno_partial_ack(struct tcpcb *tp, struct tcphdr *th); static int @@ -209,17 +311,34 @@ tcp_reass(tp, th, tlenp, m) struct tseg_qent *q; struct tseg_qent *p = NULL; struct tseg_qent *nq; - struct tseg_qent *te; + struct tseg_qent *te = NULL; struct socket *so = tp->t_inpcb->inp_socket; int flags; + int dowakeup = 0; /* * Call with th==0 after become established to * force pre-ESTABLISHED data up to user socket. */ - if (th == 0) + if (th == NULL) goto present; + /* + * 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. + */ + if (th->th_seq != tp->rcv_nxt && + tcp_reass_qsize + 1 >= tcp_reass_maxseg) { + 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 */ MALLOC(te, struct tseg_qent *, sizeof (struct tseg_qent), M_TSEGQ, M_NOWAIT); @@ -228,6 +347,7 @@ tcp_reass(tp, th, tlenp, m) m_freem(m); return (0); } + tcp_reass_qsize++; /* * Find a segment which begins after this one does. @@ -253,6 +373,7 @@ tcp_reass(tp, th, tlenp, m) tcpstat.tcps_rcvdupbyte += *tlenp; m_freem(m); FREE(te, M_TSEGQ); + tcp_reass_qsize--; /* * Try to present any queued data * at the left window edge to the user. @@ -288,6 +409,7 @@ tcp_reass(tp, th, tlenp, m) LIST_REMOVE(q, tqe_q); m_freem(q->tqe_m); FREE(q, M_TSEGQ); + tcp_reass_qsize--; q = nq; } @@ -319,9 +441,12 @@ present: LIST_REMOVE(q, tqe_q); if (so->so_state & SS_CANTRCVMORE) m_freem(q->tqe_m); - else - sbappend(&so->so_rcv, q->tqe_m); + else { + if (sbappendstream(&so->so_rcv, q->tqe_m)) + dowakeup = 1; + } FREE(q, M_TSEGQ); + tcp_reass_qsize--; q = nq; } while (q && q->tqe_th->th_seq == tp->rcv_nxt); ND6_HINT(tp); @@ -343,12 +468,36 @@ present: (((tp->t_inpcb->inp_laddr.s_addr & 0xffff) << 16) | (tp->t_inpcb->inp_faddr.s_addr & 0xffff)), 0,0,0); - } - sorwakeup(so); + } + if (dowakeup) + sorwakeup(so); /* done with socket lock held */ return (flags); } +/* + * Reduce congestion window. + */ +static void +tcp_reduce_congestion_window( + struct tcpcb *tp) +{ + u_int win; + + win = min(tp->snd_wnd, tp->snd_cwnd) / + 2 / tp->t_maxseg; + if (win < 2) + win = 2; + tp->snd_ssthresh = win * tp->t_maxseg; + ENTER_FASTRECOVERY(tp); + tp->snd_recover = tp->snd_max; + tp->t_timer[TCPT_REXMT] = 0; + tp->t_rtttime = 0; + tp->ecn_flags |= TE_SENDCWR; + tp->snd_cwnd = tp->snd_ssthresh + + tp->t_maxseg * tcprexmtthresh; +} + /* * TCP input routine, follows pages 65-76 of the @@ -356,14 +505,14 @@ present: */ #if INET6 int -tcp6_input(mp, offp, proto) +tcp6_input(mp, offp) struct mbuf **mp; - int *offp, proto; + int *offp; { register struct mbuf *m = *mp; struct in6_ifaddr *ia6; - IP6_EXTHDR_CHECK(m, *offp, sizeof(struct tcphdr), IPPROTO_DONE); + IP6_EXTHDR_CHECK(m, *offp, sizeof(struct tcphdr), return IPPROTO_DONE); /* * draft-itojun-ipv6-tcp-to-anycast @@ -407,13 +556,43 @@ tcp_input(m, off0) #endif int dropsocket = 0; int iss = 0; - u_long tiwin; + int nosock = 0; + u_int32_t 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 */ + struct sockaddr_in *next_hop = NULL; #if TCPDEBUG short ostate = 0; #endif + struct m_tag *fwd_tag; + u_char ip_ecn = IPTOS_ECN_NOTECT; + unsigned int ifscope; + + /* + * 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_flags & M_PKTHDR) && m->m_pkthdr.rcvif != NULL) + ifscope = m->m_pkthdr.rcvif->if_index; + else + ifscope = IFSCOPE_NONE; + + /* 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); + } + #if INET6 struct ip6_hdr *ip6 = NULL; int isipv6; @@ -439,7 +618,7 @@ tcp_input(m, off0) tlen = sizeof(*ip6) + ntohs(ip6->ip6_plen) - off0; if (in6_cksum(m, IPPROTO_TCP, off0, tlen)) { tcpstat.tcps_rcvbadsum++; - goto drop; + goto dropnosock; } th = (struct tcphdr *)((caddr_t)ip6 + off0); @@ -456,11 +635,11 @@ tcp_input(m, off0) */ if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { /* XXX stat */ - goto drop; + goto dropnosock; } } else #endif /* INET6 */ - { + { /* * Get IP and TCP header together in first mbuf. * Note: IP leaves IP header in first mbuf. @@ -488,12 +667,26 @@ tcp_input(m, off0) th->th_seq, th->th_ack, th->th_win); if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) { - if (apple_hwcksum_rx && (m->m_pkthdr.csum_flags & CSUM_TCP_SUM16)) { + if (m->m_pkthdr.csum_flags & CSUM_TCP_SUM16) { u_short pseudo; + char b[9]; + *(uint32_t*)&b[0] = *(uint32_t*)&ipov->ih_x1[0]; + *(uint32_t*)&b[4] = *(uint32_t*)&ipov->ih_x1[4]; + *(uint8_t*)&b[8] = *(uint8_t*)&ipov->ih_x1[8]; + bzero(ipov->ih_x1, sizeof(ipov->ih_x1)); ipov->ih_len = (u_short)tlen; + +#if BYTE_ORDER != BIG_ENDIAN HTONS(ipov->ih_len); +#endif + pseudo = in_cksum(m, sizeof (struct ip)); + + *(uint32_t*)&ipov->ih_x1[0] = *(uint32_t*)&b[0]; + *(uint32_t*)&ipov->ih_x1[4] = *(uint32_t*)&b[4]; + *(uint8_t*)&ipov->ih_x1[8] = *(uint8_t*)&b[8]; + th->th_sum = in_addword(pseudo, (m->m_pkthdr.csum_data & 0xFFFF)); } else { if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) @@ -505,24 +698,40 @@ tcp_input(m, off0) } th->th_sum ^= 0xffff; } else { + char b[9]; /* * Checksum extended TCP header and data. */ + *(uint32_t*)&b[0] = *(uint32_t*)&ipov->ih_x1[0]; + *(uint32_t*)&b[4] = *(uint32_t*)&ipov->ih_x1[4]; + *(uint8_t*)&b[8] = *(uint8_t*)&ipov->ih_x1[8]; + len = sizeof (struct ip) + tlen; bzero(ipov->ih_x1, sizeof(ipov->ih_x1)); ipov->ih_len = (u_short)tlen; + +#if BYTE_ORDER != BIG_ENDIAN HTONS(ipov->ih_len); +#endif + th->th_sum = in_cksum(m, len); + + *(uint32_t*)&ipov->ih_x1[0] = *(uint32_t*)&b[0]; + *(uint32_t*)&ipov->ih_x1[4] = *(uint32_t*)&b[4]; + *(uint8_t*)&ipov->ih_x1[8] = *(uint8_t*)&b[8]; + + tcp_in_cksum_stats(len); } if (th->th_sum) { tcpstat.tcps_rcvbadsum++; - goto drop; + goto dropnosock; } #if INET6 /* Re-initialization for later version check */ ip->ip_v = IPVERSION; #endif - } + ip_ecn = (ip->ip_tos & IPTOS_ECN_MASK); + } /* * Check that TCP offset makes sense, @@ -531,28 +740,28 @@ tcp_input(m, off0) off = th->th_off << 2; if (off < sizeof (struct tcphdr) || off > tlen) { tcpstat.tcps_rcvbadoff++; - goto drop; + 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, ); + IP6_EXTHDR_CHECK(m, off0, off, return); ip6 = mtod(m, struct ip6_hdr *); th = (struct tcphdr *)((caddr_t)ip6 + off0); } else #endif /* INET6 */ - { - if (m->m_len < sizeof(struct ip) + off) { - if ((m = m_pullup(m, sizeof (struct ip) + off)) == 0) { - tcpstat.tcps_rcvshort++; - return; + { + 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 *); + ipov = (struct ipovly *)ip; + th = (struct tcphdr *)((caddr_t)ip + off0); } - ip = mtod(m, struct ip *); - ipov = (struct ipovly *)ip; - th = (struct tcphdr *)((caddr_t)ip + off0); } - } optlen = off - sizeof (struct tcphdr); optp = (u_char *)(th + 1); /* @@ -563,11 +772,11 @@ tcp_input(m, off0) * tcp_dooptions(), etc. */ if ((optlen == TCPOLEN_TSTAMP_APPA || - (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; + *(u_int32_t *)optp == htonl(TCPOPT_TSTAMP_HDR) && + (th->th_flags & TH_SYN) == 0) { + to.to_flags |= 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 */ @@ -581,22 +790,25 @@ tcp_input(m, off0) * both the SYN and FIN bits set. This prevents e.g. nmap from * identifying the TCP/IP stack. * - * This is incompatible with RFC1644 extensions (T/TCP). + * This is a violation of the TCP specification. */ if (drop_synfin && (thflags & (TH_SYN|TH_FIN)) == (TH_SYN|TH_FIN)) - goto drop; + goto dropnosock; #endif /* * 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 /* - * Delay droping TCP, IP headers, IPv6 ext headers, and TCP options, + * 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 @@ -610,9 +822,9 @@ tcp_input(m, off0) */ findpcb: #if IPFIREWALL_FORWARD - if (ip_fw_fwd_addr != NULL + if (next_hop != NULL #if INET6 - && isipv6 == NULL /* IPv6 support is not yet */ + && isipv6 == 0 /* IPv6 support is not yet */ #endif /* INET6 */ ) { /* @@ -625,19 +837,18 @@ findpcb: /* * No, then it's new. Try find the ambushing socket */ - if (!ip_fw_fwd_addr->sin_port) { + if (!next_hop->sin_port) { inp = in_pcblookup_hash(&tcbinfo, ip->ip_src, - th->th_sport, ip_fw_fwd_addr->sin_addr, + th->th_sport, next_hop->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, + next_hop->sin_addr, + ntohs(next_hop->sin_port), 1, m->m_pkthdr.rcvif); } } - ip_fw_fwd_addr = NULL; } else #endif /* IPFIREWALL_FORWARD */ { @@ -652,18 +863,32 @@ findpcb: ip->ip_dst, th->th_dport, 1, m->m_pkthdr.rcvif); } + /* + * 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. + */ + if (inp != NULL && (inp->inp_flags & INP_BOUND_IF)) + ifscope = inp->inp_boundif; #if IPSEC + if (ipsec_bypass == 0) { #if INET6 - if (isipv6) { - if (ipsec_bypass == 0 && inp != NULL && ipsec6_in_reject_so(m, inp->inp_socket)) { - ipsec6stat.in_polvio++; - goto drop; - } - } else + if (isipv6) { + if (inp != NULL && ipsec6_in_reject_so(m, inp->inp_socket)) { + IPSEC_STAT_INCREMENT(ipsec6stat.in_polvio); + if (in_pcb_checkstate(inp, WNT_RELEASE, 0) == WNT_STOPUSING) + inp = NULL; // pretend we didn't find it + goto dropnosock; + } + } else #endif /* INET6 */ - if (ipsec_bypass == 0 && inp != NULL && ipsec4_in_reject_so(m, inp->inp_socket)) { - ipsecstat.in_polvio++; - goto drop; + if (inp != NULL && ipsec4_in_reject_so(m, inp->inp_socket)) { + IPSEC_STAT_INCREMENT(ipsecstat.in_polvio); + if (in_pcb_checkstate(inp, WNT_RELEASE, 0) == WNT_STOPUSING) + inp = NULL; // pretend we didn't find it + goto dropnosock; + } } #endif /*IPSEC*/ @@ -676,55 +901,93 @@ findpcb: if (inp == NULL) { if (log_in_vain) { #if INET6 - char dbuf[INET6_ADDRSTRLEN], sbuf[INET6_ADDRSTRLEN]; + char dbuf[MAX_IPv6_STR_LEN], sbuf[MAX_IPv6_STR_LEN]; #else /* INET6 */ - char dbuf[4*sizeof "123"], sbuf[4*sizeof "123"]; + char dbuf[MAX_IPv4_STR_LEN], sbuf[MAX_IPv4_STR_LEN]; #endif /* INET6 */ #if INET6 if (isipv6) { - strcpy(dbuf, ip6_sprintf(&ip6->ip6_dst)); - strcpy(sbuf, ip6_sprintf(&ip6->ip6_src)); + inet_ntop(AF_INET6, &ip6->ip6_dst, dbuf, sizeof(dbuf)); + inet_ntop(AF_INET6, &ip6->ip6_src, sbuf, sizeof(sbuf)); } else #endif - { - strcpy(dbuf, inet_ntoa(ip->ip_dst)); - strcpy(sbuf, inet_ntoa(ip->ip_src)); - } + { + 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)); + "Connection attempt to TCP %s:%d from %s:%d\n", + dbuf, ntohs(th->th_dport), + sbuf, + ntohs(th->th_sport)); break; 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); + "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 3: + if ((thflags & TH_SYN) && + !(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; } } if (blackhole) { - switch (blackhole) { - case 1: - if (thflags & TH_SYN) - goto drop; - break; - case 2: - goto drop; - default: - goto drop; - } + if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_type != IFT_LOOP) + switch (blackhole) { + case 1: + if (thflags & TH_SYN) + goto dropnosock; + break; + case 2: + goto dropnosock; + default: + goto dropnosock; + } } rstreason = BANDLIM_RST_CLOSEDPORT; - goto dropwithreset; + 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 + goto dropnosock; + } + + tcp_lock(so, 1, (void *)2); + if (in_pcb_checkstate(inp, WNT_RELEASE, 1) == WNT_STOPUSING) { + tcp_unlock(so, 1, (void *)2); + inp = NULL; // pretend we didn't find it + goto dropnosock; + } + tp = intotcpcb(inp); if (tp == 0) { rstreason = BANDLIM_RST_CLOSEDPORT; @@ -733,22 +996,21 @@ findpcb: if (tp->t_state == TCPS_CLOSED) goto drop; -#ifdef __APPLE__ - /* - * 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; -#endif - /* 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 CONFIG_MACF_NET + if (mac_inpcb_check_deliver(inp, m, AF_INET, SOCK_STREAM)) + goto drop; +#endif + + /* Radar 7377561: Avoid processing packets while closing a listen socket */ + if (tp->t_state == TCPS_LISTEN && (so->so_options & SO_ACCEPTCONN) == 0) + goto drop; + if (so->so_options & (SO_DEBUG|SO_ACCEPTCONN)) { #if TCPDEBUG if (so->so_options & SO_DEBUG) { @@ -764,35 +1026,75 @@ findpcb: } #endif if (so->so_options & SO_ACCEPTCONN) { - register struct tcpcb *tp0 = tp; + register struct tcpcb *tp0 = tp; struct socket *so2; -#if IPSEC struct socket *oso; -#endif + struct sockaddr_storage from; #if INET6 struct inpcb *oinp = sotoinpcb(so); #endif /* INET6 */ + unsigned int head_ifscope; + + /* Get listener's bound-to-interface, if any */ + head_ifscope = (inp->inp_flags & INP_BOUND_IF) ? + inp->inp_boundif : IFSCOPE_NONE; -#if !IPSEC /* - * Current IPsec implementation makes incorrect IPsec - * cache if this check is done here. - * So delay this until duplicated socket is created. + * 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_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_RST) { + goto drop; + } if (thflags & TH_ACK) { + tp = NULL; tcpstat.tcps_badsyn++; rstreason = BANDLIM_RST_OPENPORT; goto dropwithreset; } + + /* We come here if there is no SYN set */ + tcpstat.tcps_badsyn++; goto drop; } -#endif 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)) + goto drop; + } else +#endif /* INET6 */ + if (ip->ip_dst.s_addr == ip->ip_src.s_addr) + goto drop; + } + /* + * 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 (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 + 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; + #if INET6 /* @@ -836,28 +1138,54 @@ findpcb: } } #endif - - so2 = sonewconn(so, 0); + if (so->so_filt) { +#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; + } + 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; + } + so2 = sonewconn(so, 0, (struct sockaddr*)&from); + } else { + so2 = sonewconn(so, 0, NULL); + } if (so2 == 0) { tcpstat.tcps_listendrop++; - so2 = sodropablereq(so); - if (so2) { - if (tcp_lq_overflow) - sototcpcb(so2)->t_flags |= - TF_LQ_OVERFLOW; - tcp_drop(sototcpcb(so2), ETIMEDOUT); - so2 = sonewconn(so, 0); + if (tcp_dropdropablreq(so)) { + if (so->so_filt) + so2 = sonewconn(so, 0, (struct sockaddr*)&from); + else + so2 = sonewconn(so, 0, NULL); } - if (!so2) + if (!so2) goto drop; } -#if IPSEC + + /* Point "inp" and "tp" in tandem to new socket */ + inp = (struct inpcb *)so2->so_pcb; + tp = intotcpcb(inp); + oso = so; -#endif + tcp_unlock(so, 0, 0); /* Unlock but keep a reference on listener for now */ + so = so2; + tcp_lock(so, 1, 0); /* - * This is ugly, but .... - * * Mark socket as temporary until we're * committed to keeping it. The code at * ``drop'' and ``dropwithreset'' check the @@ -865,9 +1193,24 @@ findpcb: * 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++; - inp = (struct inpcb *)so->so_pcb; + /* + * Inherit INP_BOUND_IF from listener; testing if + * head_ifscope is non-zero is sufficient, since it + * can only be set to a non-zero value earlier if + * the listener has such a flag set. + */ +#if INET6 + if (head_ifscope != IFSCOPE_NONE && !isipv6) { +#else + if (head_ifscope != IFSCOPE_NONE) { +#endif /* INET6 */ + inp->inp_flags |= INP_BOUND_IF; + inp->inp_boundif = head_ifscope; + } #if INET6 if (isipv6) inp->in6p_laddr = ip6->ip6_dst; @@ -875,12 +1218,12 @@ findpcb: inp->inp_vflag &= ~INP_IPV6; inp->inp_vflag |= INP_IPV4; #endif /* INET6 */ - inp->inp_laddr = ip->ip_dst; + inp->inp_laddr = ip->ip_dst; #if INET6 } #endif /* INET6 */ inp->inp_lport = th->th_dport; - if (in_pcbinshash(inp) != 0) { + if (in_pcbinshash(inp, 0) != 0) { /* * Undo the assignments above if we failed to * put the PCB on the hash lists. @@ -892,30 +1235,10 @@ findpcb: #endif /* INET6 */ inp->inp_laddr.s_addr = INADDR_ANY; inp->inp_lport = 0; + tcp_lock(oso, 0, 0); /* release ref on parent */ + tcp_unlock(oso, 1, 0); goto drop; } -#if IPSEC - /* - * To avoid creating incorrectly cached IPsec - * association, this is need to be done here. - * - * Subject: (KAME-snap 748) - * From: Wayne Knowles - * ftp://ftp.kame.net/pub/mail-list/snap-users/748 - */ - 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++; - rstreason = BANDLIM_RST_OPENPORT; - goto dropwithreset; - } - goto drop; - } -#endif #if INET6 if (isipv6) { /* @@ -940,6 +1263,7 @@ findpcb: } else #endif /* INET6 */ inp->inp_options = ip_srcroute(); + tcp_lock(oso, 0, 0); #if IPSEC /* copy old policy into new socket's */ if (sotoinpcb(oso)->inp_sp) @@ -952,34 +1276,180 @@ findpcb: printf("tcp_input: could not copy policy\n"); } #endif - tp = intotcpcb(inp); + /* inherit states from the listener */ tp->t_state = TCPS_LISTEN; tp->t_flags |= tp0->t_flags & (TF_NOPUSH|TF_NOOPT|TF_NODELAY); + tp->t_keepinit = tp0->t_keepinit; + tp->t_inpcb->inp_ip_ttl = tp0->t_inpcb->inp_ip_ttl; + + /* now drop the reference on the listener */ + tcp_unlock(oso, 1, 0); /* 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 (inp->inp_pcbinfo->ipi_count < tcp_sockthreshold) { + tp->request_r_scale = max(tcp_win_scale, tp->request_r_scale); + so->so_rcv.sb_hiwat = imin(TCP_MAXWIN << tp->request_r_scale, (sb_max / (MSIZE+MCLBYTES)) * MCLBYTES); + } + else { + while (tp->request_r_scale < TCP_MAX_WINSHIFT && + TCP_MAXWIN << tp->request_r_scale < + so->so_rcv.sb_hiwat) + tp->request_r_scale++; + } KERNEL_DEBUG(DBG_FNC_TCP_NEWCONN | DBG_FUNC_END,0,0,0,0,0); } } +#if 1 + lck_mtx_assert(((struct inpcb *)so->so_pcb)->inpcb_mtx, LCK_MTX_ASSERT_OWNED); +#endif + /* + * Radar 3529618 + * This is the second part of the MSS DoS prevention code (after + * minmss on the sending side) and it deals with too many too small + * tcp packets in a too short timeframe (1 second). + * + * For every full second we count the number of received packets + * and bytes. If we get a lot of packets per second for this connection + * (tcp_minmssoverload) we take a closer look at it and compute the + * average packet size for the past second. If that is less than + * tcp_minmss we get too many packets with very small payload which + * is not good and burdens our system (and every packet generates + * a wakeup to the process connected to our socket). We can reasonable + * expect this to be small packet DoS attack to exhaust our CPU + * cycles. + * + * Care has to be taken for the minimum packet overload value. This + * value defines the minimum number of packets per second before we + * start to worry. This must not be too low to avoid killing for + * example interactive connections with many small packets like + * telnet or SSH. + * + * Setting either tcp_minmssoverload or tcp_minmss to "0" disables + * this check. + * + * Account for packet if payload packet, skip over ACK, etc. + * + * The packet per second count is done all the time and is also used + * by "DELAY_ACK" to detect streaming situations. + * + */ + if (tp->t_state == TCPS_ESTABLISHED && tlen > 0) { + if (tp->rcv_reset > tcp_now) { + tp->rcv_pps++; + tp->rcv_byps += tlen + off; + if (tp->rcv_byps > tp->rcv_maxbyps) + tp->rcv_maxbyps = tp->rcv_byps; + /* + * Setting either tcp_minmssoverload or tcp_minmss to "0" disables + * the check. + */ + if (tcp_minmss && tcp_minmssoverload && tp->rcv_pps > tcp_minmssoverload) { + if ((tp->rcv_byps / tp->rcv_pps) < tcp_minmss) { + char ipstrbuf[MAX_IPv6_STR_LEN]; + printf("too many small tcp packets from " + "%s:%u, av. %ubyte/packet, " + "dropping connection\n", +#if INET6 + isipv6 ? + inet_ntop(AF_INET6, &inp->in6p_faddr, ipstrbuf, + sizeof(ipstrbuf)) : +#endif + inet_ntop(AF_INET, &inp->inp_faddr, ipstrbuf, + sizeof(ipstrbuf)), + inp->inp_fport, + tp->rcv_byps / tp->rcv_pps); + tp = tcp_drop(tp, ECONNRESET); +/* tcpstat.tcps_minmssdrops++; */ + goto drop; + } + } + } else { + tp->rcv_reset = tcp_now + TCP_RETRANSHZ; + tp->rcv_pps = 1; + tp->rcv_byps = tlen + off; + } + } + +#if TRAFFIC_MGT + if (so->so_traffic_mgt_flags & TRAFFIC_MGT_SO_BG_REGULATE) { + tcpstat.tcps_bg_rcvtotal++; + + /* Take snapshots of pkts recv; + * tcpcb should have been initialized to 0 when allocated, + * so if 0 then this is the first time we're doing this + */ + if (!tp->tot_recv_snapshot) { + tp->tot_recv_snapshot = tcpstat.tcps_rcvtotal; + } + if (!tp->bg_recv_snapshot) { + tp->bg_recv_snapshot = tcpstat.tcps_bg_rcvtotal; + } + } +#endif /* TRAFFIC_MGT */ + /* + 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 (ip_ecn == IPTOS_ECN_CE && tp->t_state == TCPS_ESTABLISHED && + (tp->ecn_flags & (TE_SETUPSENT | TE_SETUPRECEIVED)) == + (TE_SETUPSENT | TE_SETUPRECEIVED) && tlen > 0 && + SEQ_GEQ(th->th_seq, tp->last_ack_sent) && + SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) { + tp->ecn_flags |= TE_SENDECE; + } + + /* + 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_CWR) == TH_CWR) { + tp->ecn_flags &= ~TE_SENDECE; + } + /* * Segment received on connection. * Reset idle time and keep-alive timer. */ tp->t_rcvtime = 0; if (TCPS_HAVEESTABLISHED(tp->t_state)) - tp->t_timer[TCPT_KEEP] = tcp_keepidle; + tp->t_timer[TCPT_KEEP] = TCP_KEEPIDLE(tp); /* * 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); + tcp_dooptions(tp, optp, optlen, th, &to, ifscope); + + if (tp->t_state == TCPS_SYN_SENT && (thflags & TH_SYN)) { + if (to.to_flags & TOF_SCALE) { + tp->t_flags |= TF_RCVD_SCALE; + tp->requested_s_scale = to.to_requested_s_scale; + tp->snd_wnd = th->th_win << tp->snd_scale; + tiwin = tp->snd_wnd; + } + 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 (tp->sack_enable) { + if (!(to.to_flags & TOF_SACK)) + tp->sack_enable = 0; + else + tp->t_flags |= TF_SACK_PERMIT; + } + } /* * Header prediction: check for the two common cases @@ -999,17 +1469,10 @@ findpcb: * be TH_NEEDSYN. */ if (tp->t_state == TCPS_ESTABLISHED && - (thflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK && + (thflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK|TH_ECE)) == TH_ACK && ((tp->t_flags & (TF_NEEDSYN|TF_NEEDFIN)) == 0) && - ((to.to_flag & TOF_TS) == 0 || + ((to.to_flags & 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) { @@ -1020,17 +1483,26 @@ findpcb: * NOTE that the test is modified according to the latest * proposal of the tcplw@cray.com list (Braden 1993/04/26). */ - if ((to.to_flag & TOF_TS) != 0 && + 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; } + /* Force acknowledgment if we received a FIN */ + + if (thflags & TH_FIN) + tp->t_flags |= TF_ACKNOW; + 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_wnd && - tp->t_dupacks < tcprexmtthresh) { + tp->snd_cwnd >= tp->snd_ssthresh && + ((!tcp_do_newreno && !tp->sack_enable && + tp->t_dupacks < tcprexmtthresh) || + ((tcp_do_newreno || tp->sack_enable) && + !IN_FASTRECOVERY(tp) && to.to_nsacks == 0 && + TAILQ_EMPTY(&tp->snd_holes)))) { /* * this is a pure ack for outstanding data. */ @@ -1039,24 +1511,63 @@ findpcb: * "bad retransmit" recovery */ if (tp->t_rxtshift == 1 && - tcp_now < tp->t_badrxtwin) { + tcp_now < tp->t_badrxtwin) { + ++tcpstat.tcps_sndrexmitbad; tp->snd_cwnd = tp->snd_cwnd_prev; tp->snd_ssthresh = tp->snd_ssthresh_prev; + tp->snd_recover = tp->snd_recover_prev; + if (tp->t_flags & TF_WASFRECOVERY) + ENTER_FASTRECOVERY(tp); tp->snd_nxt = tp->snd_max; tp->t_badrxtwin = 0; } - if (((to.to_flag & TOF_TS) != 0) && (to.to_tsecr != 0)) /* Makes sure we already have a TS */ + /* + * Recalculate the transmit timer / rtt. + * + * Some boxes send broken timestamp replies + * during the SYN+ACK phase, ignore + * timestamps of 0 or we could calculate a + * huge RTT and blow up the retransmit timer. + */ + if (((to.to_flags & TOF_TS) != 0) && (to.to_tsecr != 0)) { /* Makes sure we already have a TS */ + if (!tp->t_rttlow || + tp->t_rttlow > tcp_now - to.to_tsecr) + tp->t_rttlow = tcp_now - to.to_tsecr; tcp_xmit_timer(tp, - tcp_now - to.to_tsecr + 1); - else if (tp->t_rtttime && - SEQ_GT(th->th_ack, tp->t_rtseq)) + tcp_now - to.to_tsecr); + } else if (tp->t_rtttime && + SEQ_GT(th->th_ack, tp->t_rtseq)) { + if (!tp->t_rttlow || + tp->t_rttlow > tcp_now - tp->t_rtttime) + tp->t_rttlow = tcp_now - tp->t_rtttime; tcp_xmit_timer(tp, tp->t_rtttime); + } acked = th->th_ack - tp->snd_una; tcpstat.tcps_rcvackpack++; tcpstat.tcps_rcvackbyte += acked; + /* + * Grow the congestion window, if the + * connection is cwnd bound. + */ + if (tp->snd_cwnd < tp->snd_wnd) { + tp->t_bytes_acked += acked; + if (tp->t_bytes_acked > tp->snd_cwnd) { + tp->t_bytes_acked -= tp->snd_cwnd; + tp->snd_cwnd += tp->t_maxseg; + } + } sbdrop(&so->so_snd, acked); + 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; + /* + * pull snd_wl2 up to prevent seq wrap relative + * to th_ack. + */ + tp->snd_wl2 = th->th_ack; + tp->t_dupacks = 0; m_freem(m); ND6_HINT(tp); /* some progress has been done */ @@ -1074,22 +1585,38 @@ findpcb: else if (tp->t_timer[TCPT_PERSIST] == 0) tp->t_timer[TCPT_REXMT] = tp->t_rxtcur; - if (so->so_snd.sb_cc) + sowwakeup(so); /* has to be done with socket lock held */ + if ((so->so_snd.sb_cc) || (tp->t_flags & TF_ACKNOW)) { + tp->t_unacksegs = 0; (void) tcp_output(tp); - sowwakeup(so); + } + tcp_unlock(so, 1, 0); KERNEL_DEBUG(DBG_FNC_TCP_INPUT | DBG_FUNC_END,0,0,0,0,0); return; } } else if (th->th_ack == tp->snd_una && LIST_EMPTY(&tp->t_segq) && - tlen <= sbspace(&so->so_rcv)) { + 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. */ + /* Clean receiver SACK report if present */ + if (tp->sack_enable && 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; tcpstat.tcps_rcvpack++; tcpstat.tcps_rcvbyte += tlen; ND6_HINT(tp); /* some progress has been done */ @@ -1097,7 +1624,8 @@ findpcb: * Add data to socket buffer. */ m_adj(m, drop_hdrlen); /* delayed header drop */ - sbappend(&so->so_rcv, m); + if (sbappendstream(&so->so_rcv, m)) + sorwakeup(so); #if INET6 if (isipv6) { KERNEL_DEBUG(DBG_LAYER_END, ((th->th_dport << 16) | th->th_sport), @@ -1111,14 +1639,15 @@ findpcb: (((ip->ip_src.s_addr & 0xffff) << 16) | (ip->ip_dst.s_addr & 0xffff)), th->th_seq, th->th_ack, th->th_win); } - if (tcp_delack_enabled) { - TCP_DELACK_BITSET(tp->t_inpcb->hash_element); - tp->t_flags |= TF_DELACK; + if (DELAY_ACK(tp)) { + tp->t_flags |= TF_DELACK; + tp->t_unacksegs++; } else { + tp->t_unacksegs = 0; tp->t_flags |= TF_ACKNOW; tcp_output(tp); } - sorwakeup(so); + tcp_unlock(so, 1, 0); KERNEL_DEBUG(DBG_FNC_TCP_INPUT | DBG_FUNC_END,0,0,0,0,0); return; } @@ -1130,23 +1659,26 @@ findpcb: * Receive window is amount of space in rcv queue, * but not less than advertised window. */ +#if 1 + lck_mtx_assert(((struct inpcb *)so->so_pcb)->inpcb_mtx, LCK_MTX_ASSERT_OWNED); +#endif { int win; - win = sbspace(&so->so_rcv); + 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)); } switch (tp->t_state) { /* - * 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 + * 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. @@ -1160,47 +1692,9 @@ findpcb: register struct sockaddr_in6 *sin6; #endif - if (thflags & TH_RST) - goto drop; - if (thflags & TH_ACK) { - rstreason = BANDLIM_RST_OPENPORT; - 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; - } - /* - * 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 (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 +#if 1 + lck_mtx_assert(((struct inpcb *)so->so_pcb)->inpcb_mtx, LCK_MTX_ASSERT_OWNED); #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)) - goto drop; #if INET6 if (isipv6) { MALLOC(sin6, struct sockaddr_in6 *, sizeof *sin6, @@ -1225,6 +1719,9 @@ findpcb: } else #endif { +#if 0 + lck_mtx_assert(((struct inpcb *)so->so_pcb)->inpcb_mtx, LCK_MTX_ASSERT_OWNED); +#endif MALLOC(sin, struct sockaddr_in *, sizeof *sin, M_SONAME, M_NOWAIT); if (sin == NULL) @@ -1244,11 +1741,16 @@ findpcb: } FREE(sin, M_SONAME); } - if ((taop = tcp_gettaocache(inp)) == NULL) { - taop = &tao_noncached; - bzero(taop, sizeof(*taop)); + + tcp_dooptions(tp, optp, optlen, th, &to, ifscope); + + if (tp->sack_enable) { + if (!(to.to_flags & TOF_SACK)) + tp->sack_enable = 0; + else + tp->t_flags |= TF_SACK_PERMIT; } - tcp_dooptions(tp, optp, optlen, th, &to); + if (iss) tp->iss = iss; else { @@ -1264,84 +1766,23 @@ findpcb: * initialize CCsend and CCrecv. */ tp->snd_wnd = tiwin; /* initial send-window */ - tp->cc_send = CC_INC(tcp_ccgen); - tp->cc_recv = to.to_cc; - /* - * 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; - - tp->t_state = TCPS_ESTABLISHED; - - /* - * 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) || - (tlen != 0 && -#if INET6 - (isipv6 && in6_localaddr(&inp->in6p_faddr)) - || - (!isipv6 && -#endif /* INET6 */ - in_localaddr(inp->inp_faddr) -#if INET6 - ) -#endif /* INET6 */ - ))) { - TCP_DELACK_BITSET(tp->t_inpcb->hash_element); - tp->t_flags |= (TF_DELACK | TF_NEEDSYN); - } - 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; - } - /* - * TAO test failed or there was no CC option, - * do a standard 3-way handshake. - */ tp->t_flags |= TF_ACKNOW; + tp->t_unacksegs = 0; tp->t_state = TCPS_SYN_RECEIVED; - tp->t_timer[TCPT_KEEP] = tcp_keepinit; + tp->t_timer[TCPT_KEEP] = tp->t_keepinit ? tp->t_keepinit : tcp_keepinit; dropsocket = 0; /* committed to socket */ tcpstat.tcps_accepts++; + if ((thflags & (TH_ECE | TH_CWR)) == (TH_ECE | TH_CWR)) { + /* ECN-setup SYN */ + tp->ecn_flags |= (TE_SETUPRECEIVED | TE_SENDIPECT); + } +#if CONFIG_IFEF_NOWINDOWSCALE + if (tcp_obey_ifef_nowindowscale && m->m_pkthdr.rcvif != NULL && + (m->m_pkthdr.rcvif->if_eflags & IFEF_NOWINDOWSCALE)) { + /* Window scaling is not enabled on this interface */ + tp->t_flags &= ~TF_REQ_SCALE; + } +#endif goto trimthenstep6; } @@ -1371,101 +1812,81 @@ findpcb: * continue processing rest of data/controls, beginning with URG */ case TCPS_SYN_SENT: - if ((taop = tcp_gettaocache(inp)) == NULL) { - taop = &tao_noncached; - bzero(taop, sizeof(*taop)); - } - 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 { - rstreason = BANDLIM_UNLIMITED; - goto dropwithreset; - } + rstreason = BANDLIM_UNLIMITED; + goto dropwithreset; } if (thflags & TH_RST) { - if (thflags & TH_ACK) { + if ((thflags & TH_ACK) != 0) { 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 */ 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 { - rstreason = BANDLIM_UNLIMITED; - goto dropwithreset; - } - } - } else - tp->t_flags &= ~TF_RCVD_CC; tcpstat.tcps_connects++; - soisconnected(so); + + if ((thflags & (TH_ECE | TH_CWR)) == (TH_ECE)) { + /* ECN-setup SYN-ACK */ + tp->ecn_flags |= TE_SETUPRECEIVED; + } + else { + /* 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 ((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; - tp->rcv_adv += tp->rcv_wnd; tp->snd_una++; /* SYN is acked */ /* * If there's data, delay ACK; if there's also a FIN * ACKNOW will be turned on later. */ - if (tcp_delack_enabled && tlen != 0) { - TCP_DELACK_BITSET(tp->t_inpcb->hash_element); + if (DELAY_ACK(tp) && tlen != 0) { tp->t_flags |= TF_DELACK; + tp->t_unacksegs++; } - else + else { tp->t_flags |= TF_ACKNOW; + tp->t_unacksegs = 0; + } /* * Received in SYN_SENT[*] state. * Transitions: * SYN_SENT --> ESTABLISHED * SYN_SENT* --> FIN_WAIT_1 */ + tp->t_starttime = 0; if (tp->t_flags & TF_NEEDFIN) { tp->t_state = TCPS_FIN_WAIT_1; tp->t_flags &= ~TF_NEEDFIN; thflags &= ~TH_SYN; } else { tp->t_state = TCPS_ESTABLISHED; - tp->t_timer[TCPT_KEEP] = tcp_keepidle; + tp->t_timer[TCPT_KEEP] = TCP_KEEPIDLE(tp); } + /* soisconnected may lead to socket_unlock in case of upcalls, + * make sure this is done when everything is setup. + */ + soisconnected(so); } else { /* * Received initial SYN in SYN-SENT[*] state => simul- @@ -1474,34 +1895,11 @@ findpcb: * 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 { - tp->t_state = TCPS_ESTABLISHED; - tp->t_timer[TCPT_KEEP] = tcp_keepidle; - } - tp->t_flags |= TF_NEEDSYN; - } else - tp->t_state = TCPS_SYN_RECEIVED; - } else { - /* CC.NEW or no option => invalidate cache */ - taop->tao_cc = 0; - tp->t_state = TCPS_SYN_RECEIVED; - } + tp->t_state = TCPS_SYN_RECEIVED; + } trimthenstep6: @@ -1533,36 +1931,24 @@ trimthenstep6: 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; + * do normal processing. * - * else must be old SYN; drop it. - * else 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: - if ((thflags & TH_SYN) && - (to.to_flag & TOF_CC) && tp->cc_recv != 0) { - if (tp->t_state == TCPS_TIME_WAIT && - tp->t_starttime > tcp_msl) { - rstreason = BANDLIM_UNLIMITED; - goto dropwithreset; - } - if (CC_GT(to.to_cc, tp->cc_recv)) { - tp = tcp_close(tp); - goto findpcb; - } - else - goto drop; - } 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 numberering + */ + case TCPS_ESTABLISHED: + if (thflags & TH_SYN) + goto dropafterack; + break; } /* @@ -1593,6 +1979,12 @@ trimthenstep6: * 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. * 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. @@ -1613,17 +2005,25 @@ trimthenstep6: * 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: + * 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)) { + 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)))) { switch (tp->t_state) { case TCPS_SYN_RECEIVED: @@ -1631,6 +2031,10 @@ trimthenstep6: goto close; case TCPS_ESTABLISHED: + if (tp->last_ack_sent != th->th_seq) { + tcpstat.tcps_badrst++; + goto drop; + } case TCPS_FIN_WAIT_1: case TCPS_CLOSE_WAIT: /* @@ -1657,11 +2061,15 @@ trimthenstep6: goto drop; } +#if 0 + lck_mtx_assert(((struct inpcb *)so->so_pcb)->inpcb_mtx, LCK_MTX_ASSERT_OWNED); +#endif + /* * 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 && + 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. */ @@ -1682,20 +2090,12 @@ trimthenstep6: tcpstat.tcps_rcvduppack++; tcpstat.tcps_rcvdupbyte += tlen; tcpstat.tcps_pawsdrop++; - goto dropafterack; + if (tlen) + goto dropafterack; + goto drop; } } - /* - * 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 @@ -1736,6 +2136,7 @@ trimthenstep6: * But keep on processing for RST or ACK. */ tp->t_flags |= TF_ACKNOW; + tp->t_unacksegs = 0; todrop = tlen; tcpstat.tcps_rcvduppack++; tcpstat.tcps_rcvdupbyte += todrop; @@ -1786,6 +2187,7 @@ trimthenstep6: SEQ_GT(th->th_seq, tp->rcv_nxt)) { iss = tcp_new_isn(tp); tp = tcp_close(tp); + tcp_unlock(so, 1, 0); goto findpcb; } /* @@ -1797,6 +2199,7 @@ trimthenstep6: */ if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { tp->t_flags |= TF_ACKNOW; + tp->t_unacksegs = 0; tcpstat.tcps_rcvwinprobe++; } else goto dropafterack; @@ -1810,11 +2213,25 @@ trimthenstep6: /* * 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). + * 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_flag & TOF_TS) != 0 && - SEQ_LEQ(th->th_seq, tp->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; } @@ -1839,6 +2256,8 @@ trimthenstep6: if (tp->t_state == TCPS_SYN_RECEIVED || (tp->t_flags & TF_NEEDSYN)) goto step6; + else if (tp->t_flags & TF_ACKNOW) + goto dropafterack; else goto drop; } @@ -1856,7 +2275,6 @@ trimthenstep6: case TCPS_SYN_RECEIVED: tcpstat.tcps_connects++; - soisconnected(so); /* Do window scaling? */ if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == @@ -1864,36 +2282,34 @@ trimthenstep6: tp->snd_scale = tp->requested_s_scale; tp->rcv_scale = tp->request_r_scale; } - /* - * 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 */ + tp->t_starttime = 0; 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; + tp->t_timer[TCPT_KEEP] = TCP_KEEPIDLE(tp); } /* * 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) - (void) tcp_reass(tp, (struct tcphdr *)0, 0, + (void) tcp_reass(tp, (struct tcphdr *)0, &tlen, (struct mbuf *)0); tp->snd_wl1 = th->th_seq - 1; - /* fall into ... */ + + /* FALLTHROUGH */ + + /* soisconnected may lead to socket_unlock in case of upcalls, + * make sure this is done when everything is setup. + */ + soisconnected(so); /* * In ESTABLISHED state: drop duplicate ACKs; ACK out of range @@ -1910,7 +2326,13 @@ trimthenstep6: case TCPS_CLOSING: case TCPS_LAST_ACK: case TCPS_TIME_WAIT: - + if (SEQ_GT(th->th_ack, tp->snd_max)) { + tcpstat.tcps_rcvacktoomuch++; + goto dropafterack; + } + if (tp->sack_enable && + (to.to_nsacks > 0 || !TAILQ_EMPTY(&tp->snd_holes))) + tcp_sack_doack(tp, &to, th->th_ack); if (SEQ_LEQ(th->th_ack, tp->snd_una)) { if (tlen == 0 && tiwin == tp->snd_wnd) { tcpstat.tcps_rcvdupack++; @@ -1941,39 +2363,80 @@ trimthenstep6: 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 (tcp_do_newreno && SEQ_LT(th->th_ack, - tp->snd_recover)) { - /* False retransmit, should not - * cut window + else if (++tp->t_dupacks > tcprexmtthresh || + ((tcp_do_newreno || tp->sack_enable) && + IN_FASTRECOVERY(tp))) { + if (tp->sack_enable && 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; - tp->t_dupacks = 0; - (void) tcp_output(tp); - goto drop; + tp->t_unacksegs = 0; + (void) tcp_output(tp); + goto drop; + } else if (tp->t_dupacks == tcprexmtthresh) { + tcp_seq onxt = tp->snd_nxt; + u_int win; + + /* + * 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 (tp->sack_enable) { + if (IN_FASTRECOVERY(tp)) { + tp->t_dupacks = 0; + break; + } + } else if (tcp_do_newreno) { + if (SEQ_LEQ(th->th_ack, + tp->snd_recover)) { + tp->t_dupacks = 0; + break; + } } + win = min(tp->snd_wnd, tp->snd_cwnd) / + 2 / tp->t_maxseg; if (win < 2) win = 2; tp->snd_ssthresh = win * tp->t_maxseg; + ENTER_FASTRECOVERY(tp); tp->snd_recover = tp->snd_max; tp->t_timer[TCPT_REXMT] = 0; tp->t_rtttime = 0; + tp->ecn_flags |= TE_SENDCWR; + if (tp->sack_enable) { + tcpstat.tcps_sack_recovery_episode++; + tp->sack_newdata = tp->snd_nxt; + tp->snd_cwnd = tp->t_maxseg; + tp->t_unacksegs = 0; + (void) tcp_output(tp); + goto drop; + } tp->snd_nxt = th->th_ack; tp->snd_cwnd = tp->t_maxseg; + tp->t_unacksegs = 0; (void) tcp_output(tp); tp->snd_cwnd = tp->snd_ssthresh + - tp->t_maxseg * tp->t_dupacks; + 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; } } else tp->t_dupacks = 0; @@ -1983,36 +2446,73 @@ trimthenstep6: * If the congestion window was inflated to account * for the other side's cached packets, retract it. */ - if (tcp_do_newreno == 0) { - if (tp->t_dupacks >= tcprexmtthresh && - tp->snd_cwnd > tp->snd_ssthresh) - tp->snd_cwnd = tp->snd_ssthresh; - tp->t_dupacks = 0; - } else if (tp->t_dupacks >= tcprexmtthresh && - !tcp_newreno(tp, th)) { - /* - * Window inflation should have left us with approx. - * snd_ssthresh outstanding data. But in case we - * would be inclined to send a burst, better to do - * it via the slow start mechanism. - */ - if (SEQ_GT(th->th_ack + tp->snd_ssthresh, tp->snd_max)) - tp->snd_cwnd = - tp->snd_max - th->th_ack + tp->t_maxseg; - else - tp->snd_cwnd = tp->snd_ssthresh; - tp->t_dupacks = 0; - } - - if (tp->t_dupacks < tcprexmtthresh) + if (!IN_FASTRECOVERY(tp)) { + /* + * We were not in fast recovery. Reset the duplicate ack + * counter. + */ tp->t_dupacks = 0; - - if (SEQ_GT(th->th_ack, tp->snd_max)) { - tcpstat.tcps_rcvacktoomuch++; - goto dropafterack; } /* - * If we reach this point, ACK is not a duplicate, + * If the congestion window was inflated to account + * for the other side's cached packets, retract it. + */ + else { + if (tcp_do_newreno || tp->sack_enable) { + if (SEQ_LT(th->th_ack, tp->snd_recover)) { + if (tp->sack_enable) + tcp_sack_partialack(tp, th); + else + tcp_newreno_partial_ack(tp, th); + } + else { + if (tcp_do_newreno) { + int32_t ss = tp->snd_max - th->th_ack; + + /* + * Complete ack. Inflate the congestion window to + * ssthresh and exit fast recovery. + * + * Window inflation should have left us with approx. + * snd_ssthresh outstanding data. But in case we + * would be inclined to send a burst, better to do + * it via the slow start mechanism. + */ + if (ss < tp->snd_ssthresh) + tp->snd_cwnd = ss + tp->t_maxseg; + else + tp->snd_cwnd = tp->snd_ssthresh; + } + else { + /* + * Clamp the congestion window to the crossover point + * and exit fast recovery. + */ + if (tp->snd_cwnd > tp->snd_ssthresh) + tp->snd_cwnd = tp->snd_ssthresh; + } + + EXIT_FASTRECOVERY(tp); + tp->t_dupacks = 0; + tp->t_bytes_acked = 0; + } + } + else { + /* + * Clamp the congestion window to the crossover point + * and exit fast recovery in non-newreno and non-SACK case. + */ + if (tp->snd_cwnd > tp->snd_ssthresh) + tp->snd_cwnd = tp->snd_ssthresh; + EXIT_FASTRECOVERY(tp); + tp->t_dupacks = 0; + tp->t_bytes_acked = 0; + } + } + + + /* + * If we reach this point, ACK is not a duplicate, * i.e., it ACKs something we sent. */ if (tp->t_flags & TF_NEEDSYN) { @@ -2046,8 +2546,12 @@ process_ACK: * we left off. */ if (tp->t_rxtshift == 1 && tcp_now < tp->t_badrxtwin) { + ++tcpstat.tcps_sndrexmitbad; tp->snd_cwnd = tp->snd_cwnd_prev; tp->snd_ssthresh = tp->snd_ssthresh_prev; + tp->snd_recover = tp->snd_recover_prev; + if (tp->t_flags & TF_WASFRECOVERY) + ENTER_FASTRECOVERY(tp); tp->snd_nxt = tp->snd_max; tp->t_badrxtwin = 0; /* XXX probably not required */ } @@ -2061,11 +2565,21 @@ process_ACK: * timer backoff (cf., Phil Karn's retransmit alg.). * Recompute the initial retransmit timer. * Also makes sure we have a valid time stamp in hand + * + * Some boxes send broken timestamp replies + * during the SYN+ACK phase, ignore + * timestamps of 0 or we could calculate a + * huge RTT and blow up the retransmit timer. */ - if (((to.to_flag & TOF_TS) != 0) && (to.to_tsecr != 0)) - tcp_xmit_timer(tp, tcp_now - to.to_tsecr + 1); - else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) + if (((to.to_flags & TOF_TS) != 0) && (to.to_tsecr != 0)) { + if (!tp->t_rttlow || tp->t_rttlow > tcp_now - to.to_tsecr) + tp->t_rttlow = tcp_now - to.to_tsecr; + tcp_xmit_timer(tp, tcp_now - to.to_tsecr); + } else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) { + if (!tp->t_rttlow || tp->t_rttlow > tcp_now - tp->t_rtttime) + tp->t_rttlow = tcp_now - tp->t_rtttime; tcp_xmit_timer(tp, tp->t_rtttime); + } /* * If all outstanding data is acked, stop retransmit @@ -2088,24 +2602,76 @@ process_ACK: /* * 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; + if ((thflags & TH_ECE) != 0 && + (tp->ecn_flags & TE_SETUPSENT) != 0) { + /* + * Reduce the congestion window if we haven't done so. + */ + if (!(tp->sack_enable && IN_FASTRECOVERY(tp)) && + !(tcp_do_newreno && SEQ_LEQ(th->th_ack, tp->snd_recover))) { + tcp_reduce_congestion_window(tp); + } + } else if ((!tcp_do_newreno && !tp->sack_enable) || + !IN_FASTRECOVERY(tp)) { + /* + * RFC 3465 - Appropriate Byte Counting. + * + * If the window is currently less than ssthresh, + * open the window by the number of bytes ACKed by + * the last ACK, however clamp the window increase + * to an upper limit "L". + * + * In congestion avoidance phase, open the window by + * one segment each time "bytes_acked" grows to be + * greater than or equal to the congestion window. + */ - if (cw > tp->snd_ssthresh) - incr = incr * incr / cw; - /* - * If t_dupacks != 0 here, it indicates that we are still - * in NewReno fast recovery mode, so we leave the congestion - * window alone. - */ - if (tcp_do_newreno == 0 || tp->t_dupacks == 0) - tp->snd_cwnd = min(cw + incr,TCP_MAXWIN<snd_scale); + register u_int cw = tp->snd_cwnd; + register u_int incr = tp->t_maxseg; + + if (tcp_do_rfc3465) { + + if (cw >= tp->snd_ssthresh) { + tp->t_bytes_acked += acked; + if (tp->t_bytes_acked >= cw) { + /* Time to increase the window. */ + tp->t_bytes_acked -= cw; + } else { + /* No need to increase yet. */ + incr = 0; + } + } else { + /* + * If the user explicitly enables RFC3465 + * use 2*SMSS for the "L" param. Otherwise + * use the more conservative 1*SMSS. + * + * (See RFC 3465 2.3 Choosing the Limit) + */ + u_int abc_lim; + + abc_lim = (tcp_do_rfc3465_lim2 && + tp->snd_nxt == tp->snd_max) ? incr * 2 : incr; + + incr = lmin(acked, abc_lim); + } + } + else { + /* + * If the window gives us less than ssthresh packets + * in flight, open exponentially (segsz per packet). + * Otherwise open linearly: segsz per window + * (segsz^2 / cwnd per packet). + */ + + if (cw >= tp->snd_ssthresh) { + incr = max((incr * incr / cw), 1); + } + } + + + 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; @@ -2116,10 +2682,29 @@ process_ACK: tp->snd_wnd -= acked; ourfinisacked = 0; } - sowwakeup(so); + /* detect una wraparound */ + if ((tcp_do_newreno || tp->sack_enable) && + !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 ((tcp_do_newreno || tp->sack_enable) && + IN_FASTRECOVERY(tp) && + SEQ_GEQ(th->th_ack, tp->snd_recover)) + EXIT_FASTRECOVERY(tp); tp->snd_una = th->th_ack; + if (tp->sack_enable) { + 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; + + /* + * sowwakeup must happen after snd_una, et al. are updated so that + * the sequence numbers are in sync with so_snd + */ + sowwakeup(so); switch (tp->t_state) { @@ -2138,12 +2723,14 @@ process_ACK: * we'll hang forever. */ if (so->so_state & SS_CANTRCVMORE) { - soisdisconnected(so); tp->t_timer[TCPT_2MSL] = tcp_maxidle; + add_to_time_wait(tp); + soisdisconnected(so); } - add_to_time_wait(tp); tp->t_state = TCPS_FIN_WAIT_2; + /* fall through and make sure we also recognize data ACKed with the FIN */ } + tp->t_flags |= TF_ACKNOW; break; /* @@ -2158,7 +2745,7 @@ process_ACK: tcp_canceltimers(tp); /* Shorten TIME_WAIT [RFC-1644, p.28] */ if (tp->cc_recv != 0 && - tp->t_starttime < tcp_msl) + tp->t_starttime < (u_int32_t)tcp_msl) tp->t_timer[TCPT_2MSL] = tp->t_rxtcur * TCPTV_TWTRUNC; else @@ -2166,6 +2753,7 @@ process_ACK: add_to_time_wait(tp); soisdisconnected(so); } + tp->t_flags |= TF_ACKNOW; break; /* @@ -2261,7 +2849,7 @@ step6: * but if two URG's are pending at once, some out-of-band * data may creep in... ick. */ - if (th->th_urp <= (u_long)tlen + if (th->th_urp <= (u_int32_t)tlen #if SO_OOBINLINE && (so->so_options & SO_OOBINLINE) == 0 #endif @@ -2286,46 +2874,50 @@ dodata: /* XXX */ * case PRU_RCVD). If a FIN has already been received on this * connection then we just ignore the text. */ - if ((tlen || (thflags&TH_FIN)) && + if ((tlen || (thflags & TH_FIN)) && TCPS_HAVERCVDFIN(tp->t_state) == 0) { + 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 inludes th into reassembly queue of tcp with - * control block tp. Return TH_FIN if reassembly now includes - * a segment with FIN. This handle 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). + * 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) && TCPS_HAVEESTABLISHED(tp->t_state)) { -#ifdef __APPLE__ - if (tcp_delack_enabled) { - TCP_DELACK_BITSET(tp->t_inpcb->hash_element); + if (DELAY_ACK(tp) && ((tp->t_flags & TF_ACKNOW) == 0)) { tp->t_flags |= TF_DELACK; + tp->t_unacksegs++; } -#else - if (DELAY_ACK(tp)) - callout_reset(tp->tt_delack, tcp_delacktime, - tcp_timer_delack, tp); -#endif - else + else { + tp->t_unacksegs = 0; tp->t_flags |= TF_ACKNOW; + } tp->rcv_nxt += tlen; thflags = th->th_flags & TH_FIN; tcpstat.tcps_rcvpack++; tcpstat.tcps_rcvbyte += tlen; ND6_HINT(tp); - sbappend(&so->so_rcv, m); - sorwakeup(so); + if (sbappendstream(&so->so_rcv, m)) + sorwakeup(so); } else { thflags = tcp_reass(tp, th, &tlen, m); tp->t_flags |= TF_ACKNOW; + tp->t_unacksegs = 0; } + if (tlen > 0 && tp->sack_enable) + tcp_update_sack_list(tp, save_start, save_end); + if (tp->t_flags & TF_DELACK) { #if INET6 @@ -2348,7 +2940,9 @@ dodata: /* XXX */ * our window, in order to estimate the sender's * buffer size. */ - len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); + len = (u_int)(so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt)); + if (len > so->so_rcv.sb_maxused) + so->so_rcv.sb_maxused = len; } else { m_freem(m); thflags &= ~TH_FIN; @@ -2365,16 +2959,20 @@ dodata: /* XXX */ /* * 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 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)) { - TCP_DELACK_BITSET(tp->t_inpcb->hash_element); + if (DELAY_ACK(tp) && (tp->t_flags & TF_NEEDSYN)) { tp->t_flags |= TF_DELACK; + tp->t_unacksegs++; } - else + else { tp->t_flags |= TF_ACKNOW; + tp->t_unacksegs = 0; + } tp->rcv_nxt++; } switch (tp->t_state) { @@ -2384,7 +2982,7 @@ dodata: /* XXX */ * enter the CLOSE_WAIT state. */ case TCPS_SYN_RECEIVED: - /*FALLTHROUGH*/ + tp->t_starttime = 0; case TCPS_ESTABLISHED: tp->t_state = TCPS_CLOSE_WAIT; break; @@ -2407,11 +3005,12 @@ dodata: /* XXX */ tcp_canceltimers(tp); /* Shorten TIME_WAIT [RFC-1644, p.28] */ if (tp->cc_recv != 0 && - tp->t_starttime < tcp_msl) { + tp->t_starttime < (u_int32_t)tcp_msl) { tp->t_timer[TCPT_2MSL] = tp->t_rxtcur * TCPTV_TWTRUNC; /* For transaction client, force ACK now. */ tp->t_flags |= TF_ACKNOW; + tp->t_unacksegs = 0; } else tp->t_timer[TCPT_2MSL] = 2 * tcp_msl; @@ -2438,8 +3037,11 @@ dodata: /* XXX */ /* * Return any desired output. */ - if (needoutput || (tp->t_flags & TF_ACKNOW)) + if (needoutput || (tp->t_flags & TF_ACKNOW)) { + tp->t_unacksegs = 0; (void) tcp_output(tp); + } + tcp_unlock(so, 1, 0); KERNEL_DEBUG(DBG_FNC_TCP_INPUT | DBG_FUNC_END,0,0,0,0,0); return; @@ -2472,10 +3074,13 @@ dropafterack: #endif m_freem(m); tp->t_flags |= TF_ACKNOW; + tp->t_unacksegs = 0; (void) tcp_output(tp); + tcp_unlock(so, 1, 0); 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. @@ -2514,20 +3119,26 @@ dropwithreset: 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); + TH_RST, ifscope); 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); + (tcp_seq)0, TH_RST|TH_ACK, ifscope); } /* destroy temporarily created socket */ - if (dropsocket) - (void) soabort(so); + if (dropsocket) { + (void) soabort(so); + tcp_unlock(so, 1, 0); + } + else + if ((inp != NULL) && (nosock == 0)) + tcp_unlock(so, 1, 0); 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. @@ -2539,19 +3150,28 @@ drop: #endif m_freem(m); /* destroy temporarily created socket */ - if (dropsocket) - (void) soabort(so); + if (dropsocket) { + (void) soabort(so); + tcp_unlock(so, 1, 0); + } + else + if (nosock == 0) + tcp_unlock(so, 1, 0); KERNEL_DEBUG(DBG_FNC_TCP_INPUT | DBG_FUNC_END,0,0,0,0,0); return; } static void -tcp_dooptions(tp, cp, cnt, th, to) +tcp_dooptions(tp, cp, cnt, th, to, input_ifscope) +/* + * Parse TCP options and place in tcpopt. + */ struct tcpcb *tp; u_char *cp; int cnt; struct tcphdr *th; struct tcpopt *to; + unsigned int input_ifscope; { u_short mss = 0; int opt, optlen; @@ -2580,7 +3200,11 @@ tcp_dooptions(tp, cp, cnt, th, to) if (!(th->th_flags & TH_SYN)) continue; bcopy((char *) cp + 2, (char *) &mss, sizeof(mss)); + +#if BYTE_ORDER != BIG_ENDIAN NTOHS(mss); +#endif + break; case TCPOPT_WINDOW: @@ -2595,13 +3219,20 @@ tcp_dooptions(tp, cp, cnt, th, to) case TCPOPT_TIMESTAMP: if (optlen != TCPOLEN_TIMESTAMP) continue; - to->to_flag |= TOF_TS; + to->to_flags |= TOF_TS; bcopy((char *)cp + 2, (char *)&to->to_tsval, sizeof(to->to_tsval)); + +#if BYTE_ORDER != BIG_ENDIAN NTOHL(to->to_tsval); +#endif + bcopy((char *)cp + 6, (char *)&to->to_tsecr, sizeof(to->to_tsecr)); + +#if BYTE_ORDER != BIG_ENDIAN NTOHL(to->to_tsecr); +#endif /* * A timestamp received in a SYN makes @@ -2613,49 +3244,25 @@ tcp_dooptions(tp, cp, cnt, th, to) tp->ts_recent_age = tcp_now; } break; - case TCPOPT_CC: - if (optlen != TCPOLEN_CC) + case TCPOPT_SACK_PERMITTED: + if (!tcp_do_sack || + optlen != TCPOLEN_SACK_PERMITTED) 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. - */ - tp->t_flags |= TF_RCVD_CC; + to->to_flags |= TOF_SACK; break; - case TCPOPT_CCECHO: - if (optlen != TCPOLEN_CC) - continue; - if (!(th->th_flags & TH_SYN)) + case TCPOPT_SACK: + if (optlen <= 2 || (optlen - 2) % TCPOLEN_SACK != 0) continue; - to->to_flag |= TOF_CCECHO; - bcopy((char *)cp + 2, - (char *)&to->to_ccecho, sizeof(to->to_ccecho)); - NTOHL(to->to_ccecho); + to->to_nsacks = (optlen - 2) / TCPOLEN_SACK; + to->to_sacks = cp + 2; + tcpstat.tcps_sack_rcv_blocks++; + break; } } if (th->th_flags & TH_SYN) - tcp_mss(tp, mss); /* sets t_maxseg */ + tcp_mss(tp, mss, input_ifscope); /* sets t_maxseg */ } /* @@ -2736,6 +3343,8 @@ tcp_xmit_timer(tp, rtt) delta -= tp->t_rttvar >> (TCP_RTTVAR_SHIFT - TCP_DELTA_SHIFT); if ((tp->t_rttvar += delta) <= 0) tp->t_rttvar = 1; + if (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. @@ -2744,6 +3353,7 @@ tcp_xmit_timer(tp, rtt) */ tp->t_srtt = rtt << TCP_RTT_SHIFT; tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1); + tp->t_rttbest = tp->t_srtt + tp->t_rttvar; } tp->t_rtttime = 0; tp->t_rxtshift = 0; @@ -2772,6 +3382,38 @@ tcp_xmit_timer(tp, rtt) tp->t_softerror = 0; } +static inline unsigned int +tcp_maxmtu(struct rtentry *rt) +{ + unsigned int maxmtu; + + RT_LOCK_ASSERT_HELD(rt); + if (rt->rt_rmx.rmx_mtu == 0) + maxmtu = rt->rt_ifp->if_mtu; + else + maxmtu = MIN(rt->rt_rmx.rmx_mtu, rt->rt_ifp->if_mtu); + + return (maxmtu); +} + +#if INET6 +static inline unsigned int +tcp_maxmtu6(struct rtentry *rt) +{ + unsigned int maxmtu; + + RT_LOCK_ASSERT_HELD(rt); + lck_rw_lock_shared(nd_if_rwlock); + 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)); + lck_rw_done(nd_if_rwlock); + + return (maxmtu); +} +#endif + /* * Determine a reasonable value for maxseg size. * If the route is known, check route for mtu. @@ -2796,23 +3438,23 @@ tcp_xmit_timer(tp, rtt) * 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) +tcp_mss(tp, offer, input_ifscope) struct tcpcb *tp; int offer; + unsigned int input_ifscope; { register struct rtentry *rt; struct ifnet *ifp; register int rtt, mss; - u_long bufsize; + 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; @@ -2826,12 +3468,25 @@ tcp_mss(tp, offer) #else #define min_protoh (sizeof (struct tcpiphdr)) #endif + #if INET6 - if (isipv6) + if (isipv6) { rt = tcp_rtlookup6(inp); + if (rt != NULL && + (IN6_IS_ADDR_LOOPBACK(&inp->in6p_faddr) || + IN6_IS_ADDR_LINKLOCAL(&inp->in6p_faddr) || + rt->rt_gateway->sa_family == AF_LINK)) + isnetlocal = TRUE; + } else #endif /* INET6 */ - rt = tcp_rtlookup(inp); + { + rt = tcp_rtlookup(inp, input_ifscope); + if (rt != NULL && + (rt->rt_gateway->sa_family == AF_LINK || + rt->rt_ifp->if_flags & IFF_LOOPBACK)) + isnetlocal = TRUE; + } if (rt == NULL) { tp->t_maxopd = tp->t_maxseg = #if INET6 @@ -2841,6 +3496,16 @@ tcp_mss(tp, offer) return; } ifp = rt->rt_ifp; + /* + * 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 (ifp->if_type == IFT_PPP && slowlink_wsize > 0 && + ifp->if_baudrate > 9600 && ifp->if_baudrate <= 128000) { + tp->t_flags |= TF_SLOWLINK; + } so = inp->inp_socket; taop = rmx_taop(rt->rt_rmx); @@ -2860,7 +3525,12 @@ tcp_mss(tp, offer) isipv6 ? tcp_v6mssdflt : #endif /* INET6 */ tcp_mssdflt; - else + else { + /* + * Prevent DoS attack with too small MSS. Round up + * to at least minmss. + */ + offer = max(offer, tcp_minmss); /* * Sanity check: make sure that maxopd will be large * enough to allow some data on segments even is the @@ -2868,6 +3538,7 @@ tcp_mss(tp, offer) * funny things may happen in tcp_output. */ offer = max(offer, 64); + } taop->tao_mssopt = offer; /* @@ -2881,12 +3552,14 @@ tcp_mss(tp, offer) * 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)); + tp->t_rttmin = rtt / (RTM_RTTUNIT / TCP_RETRANSHZ); + else + tp->t_rttmin = isnetlocal ? tcp_TCPTV_MIN : TCP_RETRANSHZ; + tp->t_srtt = rtt / (RTM_RTTUNIT / (TCP_RETRANSHZ * 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)); + (RTM_RTTUNIT / (TCP_RETRANSHZ * TCP_RTTVAR_SCALE)); tcpstat.tcps_usedrttvar++; } else { /* default variation is +- 1 rtt */ @@ -2897,32 +3570,27 @@ tcp_mss(tp, offer) ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1, tp->t_rttmin, TCPTV_REXMTMAX); } - /* - * 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 - min_protoh; else - { - mss = -#if INET6 - (isipv6 ? nd_ifinfo[rt->rt_ifp->if_index].linkmtu : -#endif - ifp->if_mtu + tp->t_rttmin = isnetlocal ? tcp_TCPTV_MIN : TCP_RETRANSHZ; + #if INET6 - ) + mss = (isipv6 ? tcp_maxmtu6(rt) : tcp_maxmtu(rt)); +#else + mss = tcp_maxmtu(rt); #endif - - min_protoh; + mss -= min_protoh; + + if (rt->rt_rmx.rmx_mtu == 0) { #if INET6 if (isipv6) { - if (!in6_localaddr(&inp->in6p_faddr)) + if (!isnetlocal) mss = min(mss, tcp_v6mssdflt); } else #endif /* INET6 */ - if (!in_localaddr(inp->inp_faddr)) + if (!isnetlocal) mss = min(mss, tcp_mssdflt); } + mss = min(mss, offer); /* * maxopd stores the maximum length of data AND options @@ -2934,54 +3602,52 @@ tcp_mss(tp, offer) tp->t_maxopd = mss; /* - * 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. + * 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 && + 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; + tp->t_maxseg = mss; + + /* + * Calculate corrected value for sb_max; ensure to upgrade the + * numerator for large sb_max values else it will overflow. + */ + sb_max_corrected = (sb_max * (u_int64_t)MCLBYTES) / (MSIZE + MCLBYTES); -#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 + * 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 - if ((bufsize = rt->rt_rmx.rmx_sendpipe) == 0) + 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 = roundup(bufsize, mss); - if (bufsize > sb_max) - bufsize = sb_max; + 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_snd, bufsize); } tp->t_maxseg = mss; #if RTV_RPIPE - if ((bufsize = rt->rt_rmx.rmx_recvpipe) == 0) + bufsize = rt->rt_rmx.rmx_recvpipe; + if (bufsize < so->so_rcv.sb_hiwat) #endif bufsize = so->so_rcv.sb_hiwat; if (bufsize > mss) { - bufsize = roundup(bufsize, mss); - if (bufsize > sb_max) - bufsize = sb_max; + 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); } @@ -2989,16 +3655,7 @@ tcp_mss(tp, offer) * Set the slow-start flight size depending on whether this * is a local network or not. */ - if ( -#if INET6 - (isipv6 && in6_localaddr(&inp->in6p_faddr)) || - (!isipv6 && -#endif - in_localaddr(inp->inp_faddr) -#if INET6 - ) -#endif - ) + if (isnetlocal) tp->snd_cwnd = mss * ss_fltsz_local; else tp->snd_cwnd = mss * ss_fltsz; @@ -3012,7 +3669,12 @@ tcp_mss(tp, offer) */ tp->snd_ssthresh = max(2 * mss, rt->rt_rmx.rmx_ssthresh); tcpstat.tcps_usedssthresh++; + } else { + tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT; } + + /* Route locked during lookup above */ + RT_UNLOCK(rt); } /* @@ -3023,6 +3685,7 @@ tcp_mssopt(tp) struct tcpcb *tp; { struct rtentry *rt; + int mss; #if INET6 int isipv6; int min_protoh; @@ -3035,42 +3698,55 @@ tcp_mssopt(tp) #else #define min_protoh (sizeof (struct tcpiphdr)) #endif + #if INET6 if (isipv6) rt = tcp_rtlookup6(tp->t_inpcb); else #endif /* INET6 */ - rt = tcp_rtlookup(tp->t_inpcb); - if (rt == NULL) - return + rt = tcp_rtlookup(tp->t_inpcb, IFSCOPE_NONE); + if (rt == NULL) { + return ( #if INET6 isipv6 ? tcp_v6mssdflt : #endif /* INET6 */ - tcp_mssdflt; + tcp_mssdflt); + } + /* + * 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 (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; + } - return rt->rt_ifp->if_mtu - min_protoh; +#if INET6 + mss = (isipv6 ? tcp_maxmtu6(rt) : tcp_maxmtu(rt)); +#else + mss = tcp_maxmtu(rt); +#endif + /* Route locked during lookup above */ + RT_UNLOCK(rt); + return (mss - min_protoh); } - /* - * Checks for partial ack. If partial ack arrives, force the retransmission - * of the next unacknowledged segment, do not clear tp->t_dupacks, and return - * 1. By setting snd_nxt to ti_ack, this forces retransmission timer to - * be started again. If the ack advances at least to tp->snd_recover, return 0. + * On a partial ack arrives, force the retransmission of the + * next unacknowledged segment. Do not clear tp->t_dupacks. + * By setting snd_nxt to ti_ack, this forces retransmission timer to + * be started again. */ -static int -tcp_newreno(tp, th) +static void +tcp_newreno_partial_ack(tp, th) struct tcpcb *tp; struct tcphdr *th; { - if (SEQ_LT(th->th_ack, tp->snd_recover)) { tcp_seq onxt = tp->snd_nxt; - u_long ocwnd = tp->snd_cwnd; -#ifdef __APPLE__ + u_int32_t ocwnd = tp->snd_cwnd; tp->t_timer[TCPT_REXMT] = 0; -#else - callout_stop(tp->tt_rexmt); -#endif tp->t_rtttime = 0; tp->snd_nxt = th->th_ack; /* @@ -3079,6 +3755,8 @@ tcp_newreno(tp, th) * is called) */ tp->snd_cwnd = tp->t_maxseg + (th->th_ack - tp->snd_una); + tp->t_flags |= TF_ACKNOW; + tp->t_unacksegs = 0; (void) tcp_output(tp); tp->snd_cwnd = ocwnd; if (SEQ_GT(onxt, tp->snd_nxt)) @@ -3087,8 +3765,176 @@ tcp_newreno(tp, th) * Partial window deflation. Relies on fact that tp->snd_una * not updated yet. */ - tp->snd_cwnd -= (th->th_ack - tp->snd_una - tp->t_maxseg); - return (1); + if (tp->snd_cwnd > th->th_ack - tp->snd_una) + tp->snd_cwnd -= th->th_ack - tp->snd_una; + else + tp->snd_cwnd = 0; + tp->snd_cwnd += tp->t_maxseg; + +} + +/* + * 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 int rnd; + static struct timeval old_runtime; + static unsigned int cur_cnt, old_cnt; + struct timeval tv; + struct inpcb *inp = NULL; + struct tcpcb *tp; + + if ((head->so_options & SO_ACCEPTCONN) == 0) + return 0; + + so = TAILQ_FIRST(&head->so_incomp); + if (!so) + return 0; + + microtime(&tv); + if ((i = (tv.tv_sec - old_runtime.tv_sec)) != 0) { + old_runtime = tv; + old_cnt = cur_cnt / i; + cur_cnt = 0; + } + + + qlen = head->so_incqlen; + 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); + } + /* Find a connection that is not already closing (or being served) */ + while (so) { + inp = (struct inpcb *)so->so_pcb; + + sonext = TAILQ_NEXT(so, so_list); + + 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 (lck_mtx_try_lock(inp->inpcb_mtx)) { + so->so_usecount++; + if ((so->so_usecount == 2) && so->so_state & SS_INCOMP) + break; + else {/* don't use if beeing accepted or used in any other way */ + in_pcb_checkstate(inp, WNT_RELEASE, 1); + tcp_unlock(so, 1, 0); + } + } + 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) + return 0; + + TAILQ_REMOVE(&head->so_incomp, so, so_list); + tcp_unlock(head, 0, 0); + + /* Makes sure socket is still in the right state to be discarded */ + + if (in_pcb_checkstate(inp, WNT_RELEASE, 1) == WNT_STOPUSING) { + tcp_unlock(so, 1, 0); + tcp_lock(head, 0, 0); + return 0; + } + + if (so->so_usecount != 2 || !(so->so_state & SS_INCOMP)) { + /* do not discard: that socket is beeing accepted */ + tcp_unlock(so, 1, 0); + tcp_lock(head, 0, 0); + return 0; + } + + so->so_head = NULL; + + /* + * We do not want to lose track of the PCB right away in case we receive + * more segments from the peer + */ + tp = sototcpcb(so); + so->so_flags |= SOF_OVERFLOW; + tp->t_state = TCPS_TIME_WAIT; + (void) tcp_close(tp); + tp->t_unacksegs = 0; + tcpstat.tcps_drops++; + tcp_canceltimers(tp); + add_to_time_wait(tp); + + tcp_unlock(so, 1, 0); + tcp_lock(head, 0, 0); + head->so_incqlen--; + head->so_qlen--; + return 1; +} + +static int +tcp_getstat SYSCTL_HANDLER_ARGS +{ +#pragma unused(oidp, arg1, arg2) + + int error; + + if (req->oldptr == 0) { + req->oldlen= (size_t)sizeof(struct tcpstat); } + + error = SYSCTL_OUT(req, &tcpstat, MIN(sizeof (tcpstat), req->oldlen)); + + return (error); + +} + +SYSCTL_PROC(_net_inet_tcp, TCPCTL_STATS, stats, CTLFLAG_RD, 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; + + 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 + */ + + if (val < 2 || val > 3) + return (EINVAL); + + tcprexmtthresh = val; + return (0); } + +SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmt_thresh, CTLTYPE_INT|CTLFLAG_RW, + &tcprexmtthresh, 0, &sysctl_rexmtthresh, "I", "Duplicate ACK Threshold for Fast Retransmit");