X-Git-Url: https://git.saurik.com/apple/xnu.git/blobdiff_plain/4a3eedf9ecc9bbe3f3a5c6ce5e53ad199d639d32..b0d623f7f2ae71ed96e60569f61f9a9a27016e80:/bsd/netinet/tcp_timer.c diff --git a/bsd/netinet/tcp_timer.c b/bsd/netinet/tcp_timer.c index 833caaf4c..e77c28f86 100644 --- a/bsd/netinet/tcp_timer.c +++ b/bsd/netinet/tcp_timer.c @@ -1,5 +1,5 @@ /* - * Copyright (c) 2000-2007 Apple Inc. All rights reserved. + * Copyright (c) 2000-2008 Apple Inc. All rights reserved. * * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ * @@ -70,6 +70,7 @@ #include #include #include +#include #include #include /* before tcp_seq.h, for tcp_random18() */ @@ -88,6 +89,9 @@ #include #include #include +#if INET6 +#include +#endif #include #if TCPDEBUG #include @@ -151,6 +155,26 @@ static int always_keepalive = 0; SYSCTL_INT(_net_inet_tcp, OID_AUTO, always_keepalive, CTLFLAG_RW, &always_keepalive , 0, "Assume SO_KEEPALIVE on all TCP connections"); +/* + * See tcp_syn_backoff[] for interval values between SYN retransmits; + * the value set below defines the number of retransmits, before we + * disable the timestamp and window scaling options during subsequent + * SYN retransmits. Setting it to 0 disables the dropping off of those + * two options. + */ +static int tcp_broken_peer_syn_rxmit_thres = 7; +SYSCTL_INT(_net_inet_tcp, OID_AUTO, broken_peer_syn_rxmit_thres, CTLFLAG_RW, + &tcp_broken_peer_syn_rxmit_thres, 0, "Number of retransmitted SYNs before " + "TCP disables rfc1323 and rfc1644 during the rest of attempts"); + +int tcp_pmtud_black_hole_detect = 1 ; +SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_detection, CTLFLAG_RW, + &tcp_pmtud_black_hole_detect, 0, "Path MTU Discovery Black Hole Detection"); + +int tcp_pmtud_black_hole_mss = 1200 ; +SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_mss, CTLFLAG_RW, + &tcp_pmtud_black_hole_mss, 0, "Path MTU Discovery Black Hole Detection lowered MSS"); + static int tcp_keepcnt = TCPTV_KEEPCNT; static int tcp_gc_done = FALSE; /* perfromed garbage collection of "used" sockets */ /* max idle probes */ @@ -161,11 +185,12 @@ int tcp_maxidle; struct inpcbhead time_wait_slots[N_TIME_WAIT_SLOTS]; int cur_tw_slot = 0; -u_long *delack_bitmask; +u_int32_t *delack_bitmask; void add_to_time_wait_locked(struct tcpcb *tp); void add_to_time_wait(struct tcpcb *tp) ; +static void tcp_garbage_collect(struct inpcb *, int); void add_to_time_wait_locked(struct tcpcb *tp) { @@ -218,8 +243,9 @@ void add_to_time_wait(struct tcpcb *tp) * Fast timeout routine for processing delayed acks */ void -tcp_fasttimo() +tcp_fasttimo(void *arg) { +#pragma unused(arg) struct inpcb *inp; register struct tcpcb *tp; struct socket *so; @@ -243,9 +269,6 @@ tcp_fasttimo() so = inp->inp_socket; - if (so == &tcbinfo.nat_dummy_socket) - continue; - if (in_pcb_checkstate(inp, WNT_ACQUIRE, 0) == WNT_STOPUSING) continue; @@ -300,63 +323,96 @@ tpgone: timeout(tcp_fasttimo, 0, hz/TCP_RETRANSHZ); } -void -tcp_garbage_collect(inp, istimewait) - struct inpcb *inp; - int istimewait; +static void +tcp_garbage_collect(struct inpcb *inp, int istimewait) { struct socket *so; struct tcpcb *tp; + so = inp->inp_socket; + tp = intotcpcb(inp); - if (inp->inp_socket == &tcbinfo.nat_dummy_socket) - return; - - - if (!lck_mtx_try_lock(inp->inpcb_mtx)) /* skip if still in use */ - return; + /* + * Skip if still in use or busy; it would have been more efficient + * if we were to test so_usecount against 0, but this isn't possible + * due to the current implementation of tcp_dropdropablreq() where + * overflow sockets that are eligible for garbage collection have + * their usecounts set to 1. + */ + if (so->so_usecount > 1 || !lck_mtx_try_lock_spin(inp->inpcb_mtx)) + return; - so = inp->inp_socket; - tp = intotcpcb(inp); + /* Check again under the lock */ + if (so->so_usecount > 1) { + lck_mtx_unlock(inp->inpcb_mtx); + return; + } - if ((so->so_usecount == 1) && - (so->so_flags & SOF_OVERFLOW)) { - in_pcbdetach(inp); - so->so_usecount--; - lck_mtx_unlock(inp->inpcb_mtx); - return; - } - else { - if (inp->inp_wantcnt != WNT_STOPUSING) { - lck_mtx_unlock(inp->inpcb_mtx); - return; - } + /* + * Overflowed socket dropped from the listening queue? Do this + * only if we are called to clean up the time wait slots, since + * tcp_dropdropablreq() considers a socket to have been fully + * dropped after add_to_time_wait() is finished. + * Also handle the case of connections getting closed by the peer while in the queue as + * seen with rdar://6422317 + * + */ + if (so->so_usecount == 1 && + ((istimewait && (so->so_flags & SOF_OVERFLOW)) || + ((tp != NULL) && (tp->t_state == TCPS_CLOSED) && (so->so_head != NULL) + && ((so->so_state & (SS_INCOMP|SS_CANTSENDMORE|SS_CANTRCVMORE)) == + (SS_INCOMP|SS_CANTSENDMORE|SS_CANTRCVMORE))))) { + + if (inp->inp_state != INPCB_STATE_DEAD) { + /* Become a regular mutex */ + lck_mtx_convert_spin(inp->inpcb_mtx); +#if INET6 + if (INP_CHECK_SOCKAF(so, AF_INET6)) + in6_pcbdetach(inp); + else +#endif /* INET6 */ + in_pcbdetach(inp); } + so->so_usecount--; + lck_mtx_unlock(inp->inpcb_mtx); + return; + } else if (inp->inp_wantcnt != WNT_STOPUSING) { + lck_mtx_unlock(inp->inpcb_mtx); + return; + } - - if (so->so_usecount == 0) - in_pcbdispose(inp); - else { - /* Special case: - * - Check for embryonic socket stuck on listener queue (4023660) - * - overflowed socket dropped from the listening queue - * and dispose of remaining reference - */ - if ((so->so_usecount == 1) && - (((tp->t_state == TCPS_CLOSED) && (so->so_head != NULL) && (so->so_state & SS_INCOMP)) || - (istimewait && (so->so_flags & SOF_OVERFLOW)))) { - so->so_usecount--; - in_pcbdispose(inp); - } else - lck_mtx_unlock(inp->inpcb_mtx); + /* + * We get here because the PCB is no longer searchable (WNT_STOPUSING); + * detach (if needed) and dispose if it is dead (usecount is 0). This + * covers all cases, including overflow sockets and those that are + * considered as "embryonic", i.e. created by sonewconn() in TCP input + * path, and have not yet been committed. For the former, we reduce + * the usecount to 0 as done by the code above. For the latter, the + * usecount would have reduced to 0 as part calling soabort() when the + * socket is dropped at the end of tcp_input(). + */ + if (so->so_usecount == 0) { + /* Become a regular mutex */ + lck_mtx_convert_spin(inp->inpcb_mtx); + if (inp->inp_state != INPCB_STATE_DEAD) { +#if INET6 + if (INP_CHECK_SOCKAF(so, AF_INET6)) + in6_pcbdetach(inp); + else +#endif /* INET6 */ + in_pcbdetach(inp); } + in_pcbdispose(inp); + } else { + lck_mtx_unlock(inp->inpcb_mtx); + } } static int bg_cnt = 0; #define BG_COUNTER_MAX 3 void -tcp_slowtimo() +tcp_slowtimo(void) { struct inpcb *inp, *nxt; struct tcpcb *tp; @@ -366,7 +422,9 @@ tcp_slowtimo() int ostate; #endif +#if KDEBUG static int tws_checked = 0; +#endif struct inpcbinfo *pcbinfo = &tcbinfo; @@ -381,9 +439,6 @@ tcp_slowtimo() LIST_FOREACH(inp, &tcb, inp_list) { so = inp->inp_socket; - - if (so == &tcbinfo.nat_dummy_socket) - continue; if (in_pcb_checkstate(inp, WNT_ACQUIRE, 0) == WNT_STOPUSING) continue; @@ -584,8 +639,8 @@ tcp_timers(tp, timer) { register int rexmt; struct socket *so_tmp; - struct inpcbinfo *pcbinfo = &tcbinfo; struct tcptemp *t_template; + int optlen = 0; #if TCPDEBUG int ostate; @@ -612,7 +667,7 @@ tcp_timers(tp, timer) if (tp->t_state != TCPS_TIME_WAIT && tp->t_state != TCPS_FIN_WAIT_2 && tp->t_rcvtime < tcp_maxidle) { - tp->t_timer[TCPT_2MSL] = (unsigned long)tcp_keepintvl; + tp->t_timer[TCPT_2MSL] = (u_int32_t)tcp_keepintvl; } else { tp = tcp_close(tp); @@ -665,14 +720,60 @@ tcp_timers(tp, timer) tp->t_timer[TCPT_REXMT] = tp->t_rxtcur; /* - * Disable rfc1323 and rfc1644 if we havn't got any response to - * our third SYN to work-around some broken terminal servers - * (most of which have hopefully been retired) that have bad VJ - * header compression code which trashes TCP segments containing - * unknown-to-them TCP options. + * Check for potential Path MTU Discovery Black Hole + */ + + if (tcp_pmtud_black_hole_detect && (tp->t_state == TCPS_ESTABLISHED)) { + if (((tp->t_flags & (TF_PMTUD|TF_MAXSEGSNT)) == (TF_PMTUD|TF_MAXSEGSNT)) && (tp->t_rxtshift == 2)) { + /* + * Enter Path MTU Black-hole Detection mechanism: + * - Disable Path MTU Discovery (IP "DF" bit). + * - Reduce MTU to lower value than what we negociated with peer. + */ + + tp->t_flags &= ~TF_PMTUD; /* Disable Path MTU Discovery for now */ + tp->t_flags |= TF_BLACKHOLE; /* Record that we may have found a black hole */ + optlen = tp->t_maxopd - tp->t_maxseg; + tp->t_pmtud_saved_maxopd = tp->t_maxopd; /* Keep track of previous MSS */ + if (tp->t_maxopd > tcp_pmtud_black_hole_mss) + tp->t_maxopd = tcp_pmtud_black_hole_mss; /* Reduce the MSS to intermediary value */ + else { + tp->t_maxopd = /* use the default MSS */ +#if INET6 + isipv6 ? tcp_v6mssdflt : +#endif /* INET6 */ + tcp_mssdflt; + } + tp->t_maxseg = tp->t_maxopd - optlen; + } + /* + * If further retransmissions are still unsuccessful with a lowered MTU, + * maybe this isn't a Black Hole and we restore the previous MSS and + * blackhole detection flags. + */ + else { + + if ((tp->t_flags & TF_BLACKHOLE) && (tp->t_rxtshift > 4)) { + tp->t_flags |= TF_PMTUD; + tp->t_flags &= ~TF_BLACKHOLE; + optlen = tp->t_maxopd - tp->t_maxseg; + tp->t_maxopd = tp->t_pmtud_saved_maxopd; + tp->t_maxseg = tp->t_maxopd - optlen; + } + } + } + + + /* + * Disable rfc1323 and rfc1644 if we haven't got any response to + * our SYN (after we reach the threshold) to work-around some + * broken terminal servers (most of which have hopefully been + * retired) that have bad VJ header compression code which + * trashes TCP segments containing unknown-to-them TCP options. */ - if ((tp->t_state == TCPS_SYN_SENT) && (tp->t_rxtshift == 3)) - tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP|TF_REQ_CC); + if ((tp->t_state == TCPS_SYN_SENT) && + (tp->t_rxtshift == tcp_broken_peer_syn_rxmit_thres)) + tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP|TF_REQ_CC); /* * If losing, let the lower level know and try for * a better route. Also, if we backed off this far, @@ -729,15 +830,15 @@ tcp_timers(tp, timer) * growth is 2 mss. We don't allow the threshhold * to go below this.) */ - { - u_int win = min(tp->snd_wnd, tp->snd_cwnd) / 2 / tp->t_maxseg; - if (win < 2) - win = 2; - tp->snd_cwnd = tp->t_maxseg; - tp->snd_ssthresh = win * tp->t_maxseg; - tp->t_bytes_acked = 0; - tp->t_dupacks = 0; - tp->t_unacksegs = 0; + if (tp->t_state >= TCPS_ESTABLISHED) { + u_int win = min(tp->snd_wnd, tp->snd_cwnd) / 2 / tp->t_maxseg; + if (win < 2) + win = 2; + tp->snd_cwnd = tp->t_maxseg; + tp->snd_ssthresh = win * tp->t_maxseg; + tp->t_bytes_acked = 0; + tp->t_dupacks = 0; + tp->t_unacksegs = 0; } EXIT_FASTRECOVERY(tp); (void) tcp_output(tp); @@ -783,7 +884,7 @@ tcp_timers(tp, timer) if ((always_keepalive || tp->t_inpcb->inp_socket->so_options & SO_KEEPALIVE) && (tp->t_state <= TCPS_CLOSING || tp->t_state == TCPS_FIN_WAIT_2)) { - if (tp->t_rcvtime >= TCP_KEEPIDLE(tp) + (unsigned long)tcp_maxidle) + if (tp->t_rcvtime >= TCP_KEEPIDLE(tp) + (u_int32_t)tcp_maxidle) goto dropit; /* * Send a packet designed to force a response @@ -800,9 +901,16 @@ tcp_timers(tp, timer) tcpstat.tcps_keepprobe++; t_template = tcp_maketemplate(tp); if (t_template) { + unsigned int ifscope; + + if (tp->t_inpcb->inp_flags & INP_BOUND_IF) + ifscope = tp->t_inpcb->inp_boundif; + else + ifscope = IFSCOPE_NONE; + tcp_respond(tp, t_template->tt_ipgen, &t_template->tt_t, (struct mbuf *)NULL, - tp->rcv_nxt, tp->snd_una - 1, 0, NULL); + tp->rcv_nxt, tp->snd_una - 1, 0, ifscope); (void) m_free(dtom(t_template)); } tp->t_timer[TCPT_KEEP] = tcp_keepintvl;