sys/netinet/tcp_timer.c

   1 /*-
   2  * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 4. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  *      @(#)tcp_timer.c 8.2 (Berkeley) 5/24/95
  30  */
  31
  32 #include <sys/cdefs.h>
  33 __FBSDID("$FreeBSD$");
  34
  35 #include "opt_inet.h"
  36 #include "opt_inet6.h"
  37 #include "opt_tcpdebug.h"
  38 #include "opt_rss.h"
  39
  40 #include <sys/param.h>
  41 #include <sys/kernel.h>
  42 #include <sys/lock.h>
  43 #include <sys/mbuf.h>
  44 #include <sys/mutex.h>
  45 #include <sys/protosw.h>
  46 #include <sys/smp.h>
  47 #include <sys/socket.h>
  48 #include <sys/socketvar.h>
  49 #include <sys/sysctl.h>
  50 #include <sys/systm.h>
  51
  52 #include <net/if.h>
  53 #include <net/route.h>
  54 #include <net/rss_config.h>
  55 #include <net/vnet.h>
  56 #include <net/netisr.h>
  57
  58 #include <netinet/cc.h>
  59 #include <netinet/in.h>
  60 #include <netinet/in_pcb.h>
  61 #include <netinet/in_rss.h>
  62 #include <netinet/in_systm.h>
  63 #ifdef INET6
  64 #include <netinet6/in6_pcb.h>
  65 #endif
  66 #include <netinet/ip_var.h>
  67 #include <netinet/tcp_fsm.h>
  68 #include <netinet/tcp_timer.h>
  69 #include <netinet/tcp_var.h>
  70 #ifdef INET6
  71 #include <netinet6/tcp6_var.h>
  72 #endif
  73 #include <netinet/tcpip.h>
  74 #ifdef TCPDEBUG
  75 #include <netinet/tcp_debug.h>
  76 #endif
  77
  78 int     tcp_keepinit;
  79 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINIT, keepinit, CTLTYPE_INT|CTLFLAG_RW,
  80     &tcp_keepinit, 0, sysctl_msec_to_ticks, "I", "time to establish connection");
  81
  82 int     tcp_keepidle;
  83 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPIDLE, keepidle, CTLTYPE_INT|CTLFLAG_RW,
  84     &tcp_keepidle, 0, sysctl_msec_to_ticks, "I", "time before keepalive probes begin");
  85
  86 int     tcp_keepintvl;
  87 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINTVL, keepintvl, CTLTYPE_INT|CTLFLAG_RW,
  88     &tcp_keepintvl, 0, sysctl_msec_to_ticks, "I", "time between keepalive probes");
  89
  90 int     tcp_delacktime;
  91 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DELACKTIME, delacktime, CTLTYPE_INT|CTLFLAG_RW,
  92     &tcp_delacktime, 0, sysctl_msec_to_ticks, "I",
  93     "Time before a delayed ACK is sent");
  94
  95 int     tcp_msl;
  96 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, msl, CTLTYPE_INT|CTLFLAG_RW,
  97     &tcp_msl, 0, sysctl_msec_to_ticks, "I", "Maximum segment lifetime");
  98
  99 int     tcp_rexmit_min;
 100 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_min, CTLTYPE_INT|CTLFLAG_RW,
 101     &tcp_rexmit_min, 0, sysctl_msec_to_ticks, "I",
 102     "Minimum Retransmission Timeout");
 103
 104 int     tcp_rexmit_slop;
 105 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_slop, CTLTYPE_INT|CTLFLAG_RW,
 106     &tcp_rexmit_slop, 0, sysctl_msec_to_ticks, "I",
 107     "Retransmission Timer Slop");
 108
 109 static int      always_keepalive = 1;
 110 SYSCTL_INT(_net_inet_tcp, OID_AUTO, always_keepalive, CTLFLAG_RW,
 111     &always_keepalive , 0, "Assume SO_KEEPALIVE on all TCP connections");
 112
 113 int    tcp_fast_finwait2_recycle = 0;
 114 SYSCTL_INT(_net_inet_tcp, OID_AUTO, fast_finwait2_recycle, CTLFLAG_RW,
 115     &tcp_fast_finwait2_recycle, 0,
 116     "Recycle closed FIN_WAIT_2 connections faster");
 117
 118 int    tcp_finwait2_timeout;
 119 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, finwait2_timeout, CTLTYPE_INT|CTLFLAG_RW,
 120     &tcp_finwait2_timeout, 0, sysctl_msec_to_ticks, "I", "FIN-WAIT2 timeout");
 121
 122 int     tcp_keepcnt = TCPTV_KEEPCNT;
 123 SYSCTL_INT(_net_inet_tcp, OID_AUTO, keepcnt, CTLFLAG_RW, &tcp_keepcnt, 0,
 124     "Number of keepalive probes to send");
 125
 126         /* max idle probes */
 127 int     tcp_maxpersistidle;
 128
 129 static int      tcp_rexmit_drop_options = 0;
 130 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rexmit_drop_options, CTLFLAG_RW,
 131     &tcp_rexmit_drop_options, 0,
 132     "Drop TCP options from 3rd and later retransmitted SYN");
 133
 134 static VNET_DEFINE(int, tcp_pmtud_blackhole_detect);
 135 #define V_tcp_pmtud_blackhole_detect    VNET(tcp_pmtud_blackhole_detect)
 136 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_detection,
 137     CTLFLAG_RW|CTLFLAG_VNET,
 138     &VNET_NAME(tcp_pmtud_blackhole_detect), 0,
 139     "Path MTU Discovery Black Hole Detection Enabled");
 140
 141 static VNET_DEFINE(int, tcp_pmtud_blackhole_activated);
 142 #define V_tcp_pmtud_blackhole_activated \
 143     VNET(tcp_pmtud_blackhole_activated)
 144 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_activated,
 145     CTLFLAG_RD|CTLFLAG_VNET,
 146     &VNET_NAME(tcp_pmtud_blackhole_activated), 0,
 147     "Path MTU Discovery Black Hole Detection, Activation Count");
 148
 149 static VNET_DEFINE(int, tcp_pmtud_blackhole_activated_min_mss);
 150 #define V_tcp_pmtud_blackhole_activated_min_mss \
 151     VNET(tcp_pmtud_blackhole_activated_min_mss)
 152 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_activated_min_mss,
 153     CTLFLAG_RD|CTLFLAG_VNET,
 154     &VNET_NAME(tcp_pmtud_blackhole_activated_min_mss), 0,
 155     "Path MTU Discovery Black Hole Detection, Activation Count at min MSS");
 156
 157 static VNET_DEFINE(int, tcp_pmtud_blackhole_failed);
 158 #define V_tcp_pmtud_blackhole_failed    VNET(tcp_pmtud_blackhole_failed)
 159 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_failed,
 160     CTLFLAG_RD|CTLFLAG_VNET,
 161     &VNET_NAME(tcp_pmtud_blackhole_failed), 0,
 162     "Path MTU Discovery Black Hole Detection, Failure Count");
 163
 164 #ifdef INET
 165 static VNET_DEFINE(int, tcp_pmtud_blackhole_mss) = 1200;
 166 #define V_tcp_pmtud_blackhole_mss       VNET(tcp_pmtud_blackhole_mss)
 167 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_mss,
 168     CTLFLAG_RW|CTLFLAG_VNET,
 169     &VNET_NAME(tcp_pmtud_blackhole_mss), 0,
 170     "Path MTU Discovery Black Hole Detection lowered MSS");
 171 #endif
 172
 173 #ifdef INET6
 174 static VNET_DEFINE(int, tcp_v6pmtud_blackhole_mss) = 1220;
 175 #define V_tcp_v6pmtud_blackhole_mss     VNET(tcp_v6pmtud_blackhole_mss)
 176 SYSCTL_INT(_net_inet_tcp, OID_AUTO, v6pmtud_blackhole_mss,
 177     CTLFLAG_RW|CTLFLAG_VNET,
 178     &VNET_NAME(tcp_v6pmtud_blackhole_mss), 0,
 179     "Path MTU Discovery IPv6 Black Hole Detection lowered MSS");
 180 #endif
 181
 182 #ifdef  RSS
 183 static int      per_cpu_timers = 1;
 184 #else
 185 static int      per_cpu_timers = 0;
 186 #endif
 187 SYSCTL_INT(_net_inet_tcp, OID_AUTO, per_cpu_timers, CTLFLAG_RW,
 188     &per_cpu_timers , 0, "run tcp timers on all cpus");
 189
 190 #if 0
 191 #define INP_CPU(inp)    (per_cpu_timers ? (!CPU_ABSENT(((inp)->inp_flowid % (mp_maxid+1))) ? \
 192                 ((inp)->inp_flowid % (mp_maxid+1)) : curcpu) : 0)
 193 #endif
 194
 195 /*
 196  * Map the given inp to a CPU id.
 197  *
 198  * This queries RSS if it's compiled in, else it defaults to the current
 199  * CPU ID.
 200  */
 201 static inline int
 202 inp_to_cpuid(struct inpcb *inp)
 203 {
 204         u_int cpuid;
 205
 206 #ifdef  RSS
 207         if (per_cpu_timers) {
 208                 cpuid = rss_hash2cpuid(inp->inp_flowid, inp->inp_flowtype);
 209                 if (cpuid == NETISR_CPUID_NONE)
 210                         return (curcpu);        /* XXX */
 211                 else
 212                         return (cpuid);
 213         }
 214 #else
 215         /* Legacy, pre-RSS behaviour */
 216         if (per_cpu_timers) {
 217                 /*
 218                  * We don't have a flowid -> cpuid mapping, so cheat and
 219                  * just map unknown cpuids to curcpu.  Not the best, but
 220                  * apparently better than defaulting to swi 0.
 221                  */
 222                 cpuid = inp->inp_flowid % (mp_maxid + 1);
 223                 if (! CPU_ABSENT(cpuid))
 224                         return (cpuid);
 225                 return (curcpu);
 226         }
 227 #endif
 228         /* Default for RSS and non-RSS - cpuid 0 */
 229         else {
 230                 return (0);
 231         }
 232 }
 233
 234 /*
 235  * Tcp protocol timeout routine called every 500 ms.
 236  * Updates timestamps used for TCP
 237  * causes finite state machine actions if timers expire.
 238  */
 239 void
 240 tcp_slowtimo(void)
 241 {
 242         VNET_ITERATOR_DECL(vnet_iter);
 243
 244         VNET_LIST_RLOCK_NOSLEEP();
 245         VNET_FOREACH(vnet_iter) {
 246                 CURVNET_SET(vnet_iter);
 247                 (void) tcp_tw_2msl_scan(0);
 248                 CURVNET_RESTORE();
 249         }
 250         VNET_LIST_RUNLOCK_NOSLEEP();
 251 }
 252
 253 int     tcp_syn_backoff[TCP_MAXRXTSHIFT + 1] =
 254     { 1, 1, 1, 1, 1, 2, 4, 8, 16, 32, 64, 64, 64 };
 255
 256 int     tcp_backoff[TCP_MAXRXTSHIFT + 1] =
 257     { 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 512, 512, 512 };
 258
 259 static int tcp_totbackoff = 2559;       /* sum of tcp_backoff[] */
 260
 261 /*
 262  * TCP timer processing.
 263  */
 264
 265 void
 266 tcp_timer_delack(void *xtp)
 267 {
 268         struct tcpcb *tp = xtp;
 269         struct inpcb *inp;
 270         CURVNET_SET(tp->t_vnet);
 271
 272         inp = tp->t_inpcb;
 273         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 274         INP_WLOCK(inp);
 275         if (callout_pending(&tp->t_timers->tt_delack) ||
 276             !callout_active(&tp->t_timers->tt_delack)) {
 277                 INP_WUNLOCK(inp);
 278                 CURVNET_RESTORE();
 279                 return;
 280         }
 281         callout_deactivate(&tp->t_timers->tt_delack);
 282         if ((inp->inp_flags & INP_DROPPED) != 0) {
 283                 INP_WUNLOCK(inp);
 284                 CURVNET_RESTORE();
 285                 return;
 286         }
 287         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
 288                 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
 289         KASSERT((tp->t_timers->tt_flags & TT_DELACK) != 0,
 290                 ("%s: tp %p delack callout should be running", __func__, tp));
 291
 292         tp->t_flags |= TF_ACKNOW;
 293         TCPSTAT_INC(tcps_delack);
 294         (void) tcp_output(tp);
 295         INP_WUNLOCK(inp);
 296         CURVNET_RESTORE();
 297 }
 298
 299 void
 300 tcp_timer_2msl(void *xtp)
 301 {
 302         struct tcpcb *tp = xtp;
 303         struct inpcb *inp;
 304         CURVNET_SET(tp->t_vnet);
 305 #ifdef TCPDEBUG
 306         int ostate;
 307
 308         ostate = tp->t_state;
 309 #endif
 310         INP_INFO_RLOCK(&V_tcbinfo);
 311         inp = tp->t_inpcb;
 312         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 313         INP_WLOCK(inp);
 314         tcp_free_sackholes(tp);
 315         if (callout_pending(&tp->t_timers->tt_2msl) ||
 316             !callout_active(&tp->t_timers->tt_2msl)) {
 317                 INP_WUNLOCK(tp->t_inpcb);
 318                 INP_INFO_RUNLOCK(&V_tcbinfo);
 319                 CURVNET_RESTORE();
 320                 return;
 321         }
 322         callout_deactivate(&tp->t_timers->tt_2msl);
 323         if ((inp->inp_flags & INP_DROPPED) != 0) {
 324                 INP_WUNLOCK(inp);
 325                 INP_INFO_RUNLOCK(&V_tcbinfo);
 326                 CURVNET_RESTORE();
 327                 return;
 328         }
 329         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
 330                 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
 331         KASSERT((tp->t_timers->tt_flags & TT_2MSL) != 0,
 332                 ("%s: tp %p 2msl callout should be running", __func__, tp));
 333         /*
 334          * 2 MSL timeout in shutdown went off.  If we're closed but
 335          * still waiting for peer to close and connection has been idle
 336          * too long delete connection control block.  Otherwise, check
 337          * again in a bit.
 338          *
 339          * If in TIME_WAIT state just ignore as this timeout is handled in
 340          * tcp_tw_2msl_scan().
 341          *
 342          * If fastrecycle of FIN_WAIT_2, in FIN_WAIT_2 and receiver has closed,
 343          * there's no point in hanging onto FIN_WAIT_2 socket. Just close it.
 344          * Ignore fact that there were recent incoming segments.
 345          */
 346         if ((inp->inp_flags & INP_TIMEWAIT) != 0) {
 347                 INP_WUNLOCK(inp);
 348                 INP_INFO_RUNLOCK(&V_tcbinfo);
 349                 CURVNET_RESTORE();
 350                 return;
 351         }
 352         if (tcp_fast_finwait2_recycle && tp->t_state == TCPS_FIN_WAIT_2 &&
 353             tp->t_inpcb && tp->t_inpcb->inp_socket &&
 354             (tp->t_inpcb->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE)) {
 355                 TCPSTAT_INC(tcps_finwait2_drops);
 356                 tp = tcp_close(tp);
 357         } else {
 358                 if (ticks - tp->t_rcvtime <= TP_MAXIDLE(tp))
 359                        callout_reset(&tp->t_timers->tt_2msl,
 360                            TP_KEEPINTVL(tp), tcp_timer_2msl, tp);
 361                 else
 362                        tp = tcp_close(tp);
 363        }
 364
 365 #ifdef TCPDEBUG
 366         if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
 367                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 368                           PRU_SLOWTIMO);
 369 #endif
 370         if (tp != NULL)
 371                 INP_WUNLOCK(inp);
 372         INP_INFO_RUNLOCK(&V_tcbinfo);
 373         CURVNET_RESTORE();
 374 }
 375
 376 void
 377 tcp_timer_keep(void *xtp)
 378 {
 379         struct tcpcb *tp = xtp;
 380         struct tcptemp *t_template;
 381         struct inpcb *inp;
 382         CURVNET_SET(tp->t_vnet);
 383 #ifdef TCPDEBUG
 384         int ostate;
 385
 386         ostate = tp->t_state;
 387 #endif
 388         INP_INFO_RLOCK(&V_tcbinfo);
 389         inp = tp->t_inpcb;
 390         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 391         INP_WLOCK(inp);
 392         if (callout_pending(&tp->t_timers->tt_keep) ||
 393             !callout_active(&tp->t_timers->tt_keep)) {
 394                 INP_WUNLOCK(inp);
 395                 INP_INFO_RUNLOCK(&V_tcbinfo);
 396                 CURVNET_RESTORE();
 397                 return;
 398         }
 399         callout_deactivate(&tp->t_timers->tt_keep);
 400         if ((inp->inp_flags & INP_DROPPED) != 0) {
 401                 INP_WUNLOCK(inp);
 402                 INP_INFO_RUNLOCK(&V_tcbinfo);
 403                 CURVNET_RESTORE();
 404                 return;
 405         }
 406         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
 407                 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
 408         KASSERT((tp->t_timers->tt_flags & TT_KEEP) != 0,
 409                 ("%s: tp %p keep callout should be running", __func__, tp));
 410         /*
 411          * Keep-alive timer went off; send something
 412          * or drop connection if idle for too long.
 413          */
 414         TCPSTAT_INC(tcps_keeptimeo);
 415         if (tp->t_state < TCPS_ESTABLISHED)
 416                 goto dropit;
 417         if ((always_keepalive || inp->inp_socket->so_options & SO_KEEPALIVE) &&
 418             tp->t_state <= TCPS_CLOSING) {
 419                 if (ticks - tp->t_rcvtime >= TP_KEEPIDLE(tp) + TP_MAXIDLE(tp))
 420                         goto dropit;
 421                 /*
 422                  * Send a packet designed to force a response
 423                  * if the peer is up and reachable:
 424                  * either an ACK if the connection is still alive,
 425                  * or an RST if the peer has closed the connection
 426                  * due to timeout or reboot.
 427                  * Using sequence number tp->snd_una-1
 428                  * causes the transmitted zero-length segment
 429                  * to lie outside the receive window;
 430                  * by the protocol spec, this requires the
 431                  * correspondent TCP to respond.
 432                  */
 433                 TCPSTAT_INC(tcps_keepprobe);
 434                 t_template = tcpip_maketemplate(inp);
 435                 if (t_template) {
 436                         tcp_respond(tp, t_template->tt_ipgen,
 437                                     &t_template->tt_t, (struct mbuf *)NULL,
 438                                     tp->rcv_nxt, tp->snd_una - 1, 0);
 439                         free(t_template, M_TEMP);
 440                 }
 441                 callout_reset(&tp->t_timers->tt_keep, TP_KEEPINTVL(tp),
 442                     tcp_timer_keep, tp);
 443         } else
 444                 callout_reset(&tp->t_timers->tt_keep, TP_KEEPIDLE(tp),
 445                     tcp_timer_keep, tp);
 446
 447 #ifdef TCPDEBUG
 448         if (inp->inp_socket->so_options & SO_DEBUG)
 449                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 450                           PRU_SLOWTIMO);
 451 #endif
 452         INP_WUNLOCK(inp);
 453         INP_INFO_RUNLOCK(&V_tcbinfo);
 454         CURVNET_RESTORE();
 455         return;
 456
 457 dropit:
 458         TCPSTAT_INC(tcps_keepdrops);
 459         tp = tcp_drop(tp, ETIMEDOUT);
 460
 461 #ifdef TCPDEBUG
 462         if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
 463                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 464                           PRU_SLOWTIMO);
 465 #endif
 466         if (tp != NULL)
 467                 INP_WUNLOCK(tp->t_inpcb);
 468         INP_INFO_RUNLOCK(&V_tcbinfo);
 469         CURVNET_RESTORE();
 470 }
 471
 472 void
 473 tcp_timer_persist(void *xtp)
 474 {
 475         struct tcpcb *tp = xtp;
 476         struct inpcb *inp;
 477         CURVNET_SET(tp->t_vnet);
 478 #ifdef TCPDEBUG
 479         int ostate;
 480
 481         ostate = tp->t_state;
 482 #endif
 483         INP_INFO_RLOCK(&V_tcbinfo);
 484         inp = tp->t_inpcb;
 485         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 486         INP_WLOCK(inp);
 487         if (callout_pending(&tp->t_timers->tt_persist) ||
 488             !callout_active(&tp->t_timers->tt_persist)) {
 489                 INP_WUNLOCK(inp);
 490                 INP_INFO_RUNLOCK(&V_tcbinfo);
 491                 CURVNET_RESTORE();
 492                 return;
 493         }
 494         callout_deactivate(&tp->t_timers->tt_persist);
 495         if ((inp->inp_flags & INP_DROPPED) != 0) {
 496                 INP_WUNLOCK(inp);
 497                 INP_INFO_RUNLOCK(&V_tcbinfo);
 498                 CURVNET_RESTORE();
 499                 return;
 500         }
 501         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
 502                 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
 503         KASSERT((tp->t_timers->tt_flags & TT_PERSIST) != 0,
 504                 ("%s: tp %p persist callout should be running", __func__, tp));
 505         /*
 506          * Persistance timer into zero window.
 507          * Force a byte to be output, if possible.
 508          */
 509         TCPSTAT_INC(tcps_persisttimeo);
 510         /*
 511          * Hack: if the peer is dead/unreachable, we do not
 512          * time out if the window is closed.  After a full
 513          * backoff, drop the connection if the idle time
 514          * (no responses to probes) reaches the maximum
 515          * backoff that we would use if retransmitting.
 516          */
 517         if (tp->t_rxtshift == TCP_MAXRXTSHIFT &&
 518             (ticks - tp->t_rcvtime >= tcp_maxpersistidle ||
 519              ticks - tp->t_rcvtime >= TCP_REXMTVAL(tp) * tcp_totbackoff)) {
 520                 TCPSTAT_INC(tcps_persistdrop);
 521                 tp = tcp_drop(tp, ETIMEDOUT);
 522                 goto out;
 523         }
 524         /*
 525          * If the user has closed the socket then drop a persisting
 526          * connection after a much reduced timeout.
 527          */
 528         if (tp->t_state > TCPS_CLOSE_WAIT &&
 529             (ticks - tp->t_rcvtime) >= TCPTV_PERSMAX) {
 530                 TCPSTAT_INC(tcps_persistdrop);
 531                 tp = tcp_drop(tp, ETIMEDOUT);
 532                 goto out;
 533         }
 534         tcp_setpersist(tp);
 535         tp->t_flags |= TF_FORCEDATA;
 536         (void) tcp_output(tp);
 537         tp->t_flags &= ~TF_FORCEDATA;
 538
 539 out:
 540 #ifdef TCPDEBUG
 541         if (tp != NULL && tp->t_inpcb->inp_socket->so_options & SO_DEBUG)
 542                 tcp_trace(TA_USER, ostate, tp, NULL, NULL, PRU_SLOWTIMO);
 543 #endif
 544         if (tp != NULL)
 545                 INP_WUNLOCK(inp);
 546         INP_INFO_RUNLOCK(&V_tcbinfo);
 547         CURVNET_RESTORE();
 548 }
 549
 550 void
 551 tcp_timer_rexmt(void * xtp)
 552 {
 553         struct tcpcb *tp = xtp;
 554         CURVNET_SET(tp->t_vnet);
 555         int rexmt;
 556         int headlocked;
 557         struct inpcb *inp;
 558 #ifdef TCPDEBUG
 559         int ostate;
 560
 561         ostate = tp->t_state;
 562 #endif
 563
 564         INP_INFO_RLOCK(&V_tcbinfo);
 565         inp = tp->t_inpcb;
 566         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 567         INP_WLOCK(inp);
 568         if (callout_pending(&tp->t_timers->tt_rexmt) ||
 569             !callout_active(&tp->t_timers->tt_rexmt)) {
 570                 INP_WUNLOCK(inp);
 571                 INP_INFO_RUNLOCK(&V_tcbinfo);
 572                 CURVNET_RESTORE();
 573                 return;
 574         }
 575         callout_deactivate(&tp->t_timers->tt_rexmt);
 576         if ((inp->inp_flags & INP_DROPPED) != 0) {
 577                 INP_WUNLOCK(inp);
 578                 INP_INFO_RUNLOCK(&V_tcbinfo);
 579                 CURVNET_RESTORE();
 580                 return;
 581         }
 582         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
 583                 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
 584         KASSERT((tp->t_timers->tt_flags & TT_REXMT) != 0,
 585                 ("%s: tp %p rexmt callout should be running", __func__, tp));
 586         tcp_free_sackholes(tp);
 587         /*
 588          * Retransmission timer went off.  Message has not
 589          * been acked within retransmit interval.  Back off
 590          * to a longer retransmit interval and retransmit one segment.
 591          */
 592         if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) {
 593                 tp->t_rxtshift = TCP_MAXRXTSHIFT;
 594                 TCPSTAT_INC(tcps_timeoutdrop);
 595
 596                 tp = tcp_drop(tp, tp->t_softerror ?
 597                               tp->t_softerror : ETIMEDOUT);
 598                 headlocked = 1;
 599                 goto out;
 600         }
 601         INP_INFO_RUNLOCK(&V_tcbinfo);
 602         headlocked = 0;
 603         if (tp->t_state == TCPS_SYN_SENT) {
 604                 /*
 605                  * If the SYN was retransmitted, indicate CWND to be
 606                  * limited to 1 segment in cc_conn_init().
 607                  */
 608                 tp->snd_cwnd = 1;
 609         } else if (tp->t_rxtshift == 1) {
 610                 /*
 611                  * first retransmit; record ssthresh and cwnd so they can
 612                  * be recovered if this turns out to be a "bad" retransmit.
 613                  * A retransmit is considered "bad" if an ACK for this
 614                  * segment is received within RTT/2 interval; the assumption
 615                  * here is that the ACK was already in flight.  See
 616                  * "On Estimating End-to-End Network Path Properties" by
 617                  * Allman and Paxson for more details.
 618                  */
 619                 tp->snd_cwnd_prev = tp->snd_cwnd;
 620                 tp->snd_ssthresh_prev = tp->snd_ssthresh;
 621                 tp->snd_recover_prev = tp->snd_recover;
 622                 if (IN_FASTRECOVERY(tp->t_flags))
 623                         tp->t_flags |= TF_WASFRECOVERY;
 624                 else
 625                         tp->t_flags &= ~TF_WASFRECOVERY;
 626                 if (IN_CONGRECOVERY(tp->t_flags))
 627                         tp->t_flags |= TF_WASCRECOVERY;
 628                 else
 629                         tp->t_flags &= ~TF_WASCRECOVERY;
 630                 tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1));
 631                 tp->t_flags |= TF_PREVVALID;
 632         } else
 633                 tp->t_flags &= ~TF_PREVVALID;
 634         TCPSTAT_INC(tcps_rexmttimeo);
 635         if (tp->t_state == TCPS_SYN_SENT)
 636                 rexmt = TCPTV_RTOBASE * tcp_syn_backoff[tp->t_rxtshift];
 637         else
 638                 rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift];
 639         TCPT_RANGESET(tp->t_rxtcur, rexmt,
 640                       tp->t_rttmin, TCPTV_REXMTMAX);
 641
 642         /*
 643          * We enter the path for PLMTUD if connection is established or, if
 644          * connection is FIN_WAIT_1 status, reason for the last is that if
 645          * amount of data we send is very small, we could send it in couple of
 646          * packets and process straight to FIN. In that case we won't catch
 647          * ESTABLISHED state.
 648          */
 649         if (V_tcp_pmtud_blackhole_detect && (((tp->t_state == TCPS_ESTABLISHED))
 650             || (tp->t_state == TCPS_FIN_WAIT_1))) {
 651                 int optlen;
 652 #ifdef INET6
 653                 int isipv6;
 654 #endif
 655
 656                 if (((tp->t_flags2 & (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) ==
 657                     (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) &&
 658                     (tp->t_rxtshift <= 2)) {
 659                         /*
 660                          * Enter Path MTU Black-hole Detection mechanism:
 661                          * - Disable Path MTU Discovery (IP "DF" bit).
 662                          * - Reduce MTU to lower value than what we
 663                          *   negotiated with peer.
 664                          */
 665                         /* Record that we may have found a black hole. */
 666                         tp->t_flags2 |= TF2_PLPMTU_BLACKHOLE;
 667
 668                         /* Keep track of previous MSS. */
 669                         optlen = tp->t_maxopd - tp->t_maxseg;
 670                         tp->t_pmtud_saved_maxopd = tp->t_maxopd;
 671
 672                         /*
 673                          * Reduce the MSS to blackhole value or to the default
 674                          * in an attempt to retransmit.
 675                          */
 676 #ifdef INET6
 677                         isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) ? 1 : 0;
 678                         if (isipv6 &&
 679                             tp->t_maxopd > V_tcp_v6pmtud_blackhole_mss) {
 680                                 /* Use the sysctl tuneable blackhole MSS. */
 681                                 tp->t_maxopd = V_tcp_v6pmtud_blackhole_mss;
 682                                 V_tcp_pmtud_blackhole_activated++;
 683                         } else if (isipv6) {
 684                                 /* Use the default MSS. */
 685                                 tp->t_maxopd = V_tcp_v6mssdflt;
 686                                 /*
 687                                  * Disable Path MTU Discovery when we switch to
 688                                  * minmss.
 689                                  */
 690                                 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
 691                                 V_tcp_pmtud_blackhole_activated_min_mss++;
 692                         }
 693 #endif
 694 #if defined(INET6) && defined(INET)
 695                         else
 696 #endif
 697 #ifdef INET
 698                         if (tp->t_maxopd > V_tcp_pmtud_blackhole_mss) {
 699                                 /* Use the sysctl tuneable blackhole MSS. */
 700                                 tp->t_maxopd = V_tcp_pmtud_blackhole_mss;
 701                                 V_tcp_pmtud_blackhole_activated++;
 702                         } else {
 703                                 /* Use the default MSS. */
 704                                 tp->t_maxopd = V_tcp_mssdflt;
 705                                 /*
 706                                  * Disable Path MTU Discovery when we switch to
 707                                  * minmss.
 708                                  */
 709                                 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
 710                                 V_tcp_pmtud_blackhole_activated_min_mss++;
 711                         }
 712 #endif
 713                         tp->t_maxseg = tp->t_maxopd - optlen;
 714                         /*
 715                          * Reset the slow-start flight size
 716                          * as it may depend on the new MSS.
 717                          */
 718                         if (CC_ALGO(tp)->conn_init != NULL)
 719                                 CC_ALGO(tp)->conn_init(tp->ccv);
 720                 } else {
 721                         /*
 722                          * If further retransmissions are still unsuccessful
 723                          * with a lowered MTU, maybe this isn't a blackhole and
 724                          * we restore the previous MSS and blackhole detection
 725                          * flags.
 726                          */
 727                         if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) &&
 728                             (tp->t_rxtshift > 4)) {
 729                                 tp->t_flags2 |= TF2_PLPMTU_PMTUD;
 730                                 tp->t_flags2 &= ~TF2_PLPMTU_BLACKHOLE;
 731                                 optlen = tp->t_maxopd - tp->t_maxseg;
 732                                 tp->t_maxopd = tp->t_pmtud_saved_maxopd;
 733                                 tp->t_maxseg = tp->t_maxopd - optlen;
 734                                 V_tcp_pmtud_blackhole_failed++;
 735                                 /*
 736                                  * Reset the slow-start flight size as it
 737                                  * may depend on the new MSS.
 738                                  */
 739                                 if (CC_ALGO(tp)->conn_init != NULL)
 740                                         CC_ALGO(tp)->conn_init(tp->ccv);
 741                         }
 742                 }
 743         }
 744
 745         /*
 746          * Disable RFC1323 and SACK if we haven't got any response to
 747          * our third SYN to work-around some broken terminal servers
 748          * (most of which have hopefully been retired) that have bad VJ
 749          * header compression code which trashes TCP segments containing
 750          * unknown-to-them TCP options.
 751          */
 752         if (tcp_rexmit_drop_options && (tp->t_state == TCPS_SYN_SENT) &&
 753             (tp->t_rxtshift == 3))
 754                 tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP|TF_SACK_PERMIT);
 755         /*
 756          * If we backed off this far, our srtt estimate is probably bogus.
 757          * Clobber it so we'll take the next rtt measurement as our srtt;
 758          * move the current srtt into rttvar to keep the current
 759          * retransmit times until then.
 760          */
 761         if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) {
 762 #ifdef INET6
 763                 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0)
 764                         in6_losing(tp->t_inpcb);
 765 #endif
 766                 tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT);
 767                 tp->t_srtt = 0;
 768         }
 769         tp->snd_nxt = tp->snd_una;
 770         tp->snd_recover = tp->snd_max;
 771         /*
 772          * Force a segment to be sent.
 773          */
 774         tp->t_flags |= TF_ACKNOW;
 775         /*
 776          * If timing a segment in this window, stop the timer.
 777          */
 778         tp->t_rtttime = 0;
 779
 780         cc_cong_signal(tp, NULL, CC_RTO);
 781
 782         (void) tcp_output(tp);
 783
 784 out:
 785 #ifdef TCPDEBUG
 786         if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
 787                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 788                           PRU_SLOWTIMO);
 789 #endif
 790         if (tp != NULL)
 791                 INP_WUNLOCK(inp);
 792         if (headlocked)
 793                 INP_INFO_RUNLOCK(&V_tcbinfo);
 794         CURVNET_RESTORE();
 795 }
 796
 797 void
 798 tcp_timer_activate(struct tcpcb *tp, uint32_t timer_type, u_int delta)
 799 {
 800         struct callout *t_callout;
 801         timeout_t *f_callout;
 802         struct inpcb *inp = tp->t_inpcb;
 803         int cpu = inp_to_cpuid(inp);
 804
 805 #ifdef TCP_OFFLOAD
 806         if (tp->t_flags & TF_TOE)
 807                 return;
 808 #endif
 809
 810         if (tp->t_timers->tt_flags & TT_STOPPED)
 811                 return;
 812
 813         switch (timer_type) {
 814                 case TT_DELACK:
 815                         t_callout = &tp->t_timers->tt_delack;
 816                         f_callout = tcp_timer_delack;
 817                         break;
 818                 case TT_REXMT:
 819                         t_callout = &tp->t_timers->tt_rexmt;
 820                         f_callout = tcp_timer_rexmt;
 821                         break;
 822                 case TT_PERSIST:
 823                         t_callout = &tp->t_timers->tt_persist;
 824                         f_callout = tcp_timer_persist;
 825                         break;
 826                 case TT_KEEP:
 827                         t_callout = &tp->t_timers->tt_keep;
 828                         f_callout = tcp_timer_keep;
 829                         break;
 830                 case TT_2MSL:
 831                         t_callout = &tp->t_timers->tt_2msl;
 832                         f_callout = tcp_timer_2msl;
 833                         break;
 834                 default:
 835                         panic("tp %p bad timer_type %#x", tp, timer_type);
 836                 }
 837         if (delta == 0) {
 838                 if ((tp->t_timers->tt_flags & timer_type) &&
 839                     callout_stop(t_callout)) {
 840                         tp->t_timers->tt_flags &= ~timer_type;
 841                 }
 842         } else {
 843                 if ((tp->t_timers->tt_flags & timer_type) == 0) {
 844                         tp->t_timers->tt_flags |= timer_type;
 845                         callout_reset_on(t_callout, delta, f_callout, tp, cpu);
 846                 } else {
 847                         /* Reset already running callout on the same CPU. */
 848                         callout_reset(t_callout, delta, f_callout, tp);
 849                 }
 850         }
 851 }
 852
 853 int
 854 tcp_timer_active(struct tcpcb *tp, uint32_t timer_type)
 855 {
 856         struct callout *t_callout;
 857
 858         switch (timer_type) {
 859                 case TT_DELACK:
 860                         t_callout = &tp->t_timers->tt_delack;
 861                         break;
 862                 case TT_REXMT:
 863                         t_callout = &tp->t_timers->tt_rexmt;
 864                         break;
 865                 case TT_PERSIST:
 866                         t_callout = &tp->t_timers->tt_persist;
 867                         break;
 868                 case TT_KEEP:
 869                         t_callout = &tp->t_timers->tt_keep;
 870                         break;
 871                 case TT_2MSL:
 872                         t_callout = &tp->t_timers->tt_2msl;
 873                         break;
 874                 default:
 875                         panic("tp %p bad timer_type %#x", tp, timer_type);
 876                 }
 877         return callout_active(t_callout);
 878 }
 879
 880 void
 881 tcp_timer_stop(struct tcpcb *tp, uint32_t timer_type)
 882 {
 883         struct callout *t_callout;
 884         timeout_t *f_callout;
 885
 886         tp->t_timers->tt_flags |= TT_STOPPED;
 887
 888         switch (timer_type) {
 889                 case TT_DELACK:
 890                         t_callout = &tp->t_timers->tt_delack;
 891                         f_callout = tcp_timer_delack_discard;
 892                         break;
 893                 case TT_REXMT:
 894                         t_callout = &tp->t_timers->tt_rexmt;
 895                         f_callout = tcp_timer_rexmt_discard;
 896                         break;
 897                 case TT_PERSIST:
 898                         t_callout = &tp->t_timers->tt_persist;
 899                         f_callout = tcp_timer_persist_discard;
 900                         break;
 901                 case TT_KEEP:
 902                         t_callout = &tp->t_timers->tt_keep;
 903                         f_callout = tcp_timer_keep_discard;
 904                         break;
 905                 case TT_2MSL:
 906                         t_callout = &tp->t_timers->tt_2msl;
 907                         f_callout = tcp_timer_2msl_discard;
 908                         break;
 909                 default:
 910                         panic("tp %p bad timer_type %#x", tp, timer_type);
 911                 }
 912
 913         if (tp->t_timers->tt_flags & timer_type) {
 914                 if (callout_stop(t_callout)) {
 915                         tp->t_timers->tt_flags &= ~timer_type;
 916                 } else {
 917                         /*
 918                          * Can't stop the callout, defer tcpcb actual deletion
 919                          * to the last tcp timer discard callout.
 920                          * The TT_STOPPED flag will ensure that no tcp timer
 921                          * callouts can be restarted on our behalf, and
 922                          * past this point currently running callouts waiting
 923                          * on inp lock will return right away after the
 924                          * classical check for callout reset/stop events:
 925                          * callout_pending() || !callout_active()
 926                          */
 927                         callout_reset(t_callout, 1, f_callout, tp);
 928                 }
 929         }
 930 }
 931
 932 #define ticks_to_msecs(t)       (1000*(t) / hz)
 933
 934 void
 935 tcp_timer_to_xtimer(struct tcpcb *tp, struct tcp_timer *timer,
 936     struct xtcp_timer *xtimer)
 937 {
 938         sbintime_t now;
 939
 940         bzero(xtimer, sizeof(*xtimer));
 941         if (timer == NULL)
 942                 return;
 943         now = getsbinuptime();
 944         if (callout_active(&timer->tt_delack))
 945                 xtimer->tt_delack = (timer->tt_delack.c_time - now) / SBT_1MS;
 946         if (callout_active(&timer->tt_rexmt))
 947                 xtimer->tt_rexmt = (timer->tt_rexmt.c_time - now) / SBT_1MS;
 948         if (callout_active(&timer->tt_persist))
 949                 xtimer->tt_persist = (timer->tt_persist.c_time - now) / SBT_1MS;
 950         if (callout_active(&timer->tt_keep))
 951                 xtimer->tt_keep = (timer->tt_keep.c_time - now) / SBT_1MS;
 952         if (callout_active(&timer->tt_2msl))
 953                 xtimer->tt_2msl = (timer->tt_2msl.c_time - now) / SBT_1MS;
 954         xtimer->t_rcvtime = ticks_to_msecs(ticks - tp->t_rcvtime);
 955 }