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_kdtrace.h>
  61 #include <netinet/in_pcb.h>
  62 #include <netinet/in_rss.h>
  63 #include <netinet/in_systm.h>
  64 #ifdef INET6
  65 #include <netinet6/in6_pcb.h>
  66 #endif
  67 #include <netinet/ip_var.h>
  68 #include <netinet/tcp_fsm.h>
  69 #include <netinet/tcp_timer.h>
  70 #include <netinet/tcp_var.h>
  71 #ifdef INET6
  72 #include <netinet6/tcp6_var.h>
  73 #endif
  74 #include <netinet/tcpip.h>
  75 #ifdef TCPDEBUG
  76 #include <netinet/tcp_debug.h>
  77 #endif
  78
  79 int     tcp_keepinit;
  80 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINIT, keepinit, CTLTYPE_INT|CTLFLAG_RW,
  81     &tcp_keepinit, 0, sysctl_msec_to_ticks, "I", "time to establish connection");
  82
  83 int     tcp_keepidle;
  84 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPIDLE, keepidle, CTLTYPE_INT|CTLFLAG_RW,
  85     &tcp_keepidle, 0, sysctl_msec_to_ticks, "I", "time before keepalive probes begin");
  86
  87 int     tcp_keepintvl;
  88 SYSCTL_PROC(_net_inet_tcp, TCPCTL_KEEPINTVL, keepintvl, CTLTYPE_INT|CTLFLAG_RW,
  89     &tcp_keepintvl, 0, sysctl_msec_to_ticks, "I", "time between keepalive probes");
  90
  91 int     tcp_delacktime;
  92 SYSCTL_PROC(_net_inet_tcp, TCPCTL_DELACKTIME, delacktime, CTLTYPE_INT|CTLFLAG_RW,
  93     &tcp_delacktime, 0, sysctl_msec_to_ticks, "I",
  94     "Time before a delayed ACK is sent");
  95
  96 int     tcp_msl;
  97 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, msl, CTLTYPE_INT|CTLFLAG_RW,
  98     &tcp_msl, 0, sysctl_msec_to_ticks, "I", "Maximum segment lifetime");
  99
 100 int     tcp_rexmit_min;
 101 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_min, CTLTYPE_INT|CTLFLAG_RW,
 102     &tcp_rexmit_min, 0, sysctl_msec_to_ticks, "I",
 103     "Minimum Retransmission Timeout");
 104
 105 int     tcp_rexmit_slop;
 106 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, rexmit_slop, CTLTYPE_INT|CTLFLAG_RW,
 107     &tcp_rexmit_slop, 0, sysctl_msec_to_ticks, "I",
 108     "Retransmission Timer Slop");
 109
 110 static int      always_keepalive = 1;
 111 SYSCTL_INT(_net_inet_tcp, OID_AUTO, always_keepalive, CTLFLAG_RW,
 112     &always_keepalive , 0, "Assume SO_KEEPALIVE on all TCP connections");
 113
 114 int    tcp_fast_finwait2_recycle = 0;
 115 SYSCTL_INT(_net_inet_tcp, OID_AUTO, fast_finwait2_recycle, CTLFLAG_RW,
 116     &tcp_fast_finwait2_recycle, 0,
 117     "Recycle closed FIN_WAIT_2 connections faster");
 118
 119 int    tcp_finwait2_timeout;
 120 SYSCTL_PROC(_net_inet_tcp, OID_AUTO, finwait2_timeout, CTLTYPE_INT|CTLFLAG_RW,
 121     &tcp_finwait2_timeout, 0, sysctl_msec_to_ticks, "I", "FIN-WAIT2 timeout");
 122
 123 int     tcp_keepcnt = TCPTV_KEEPCNT;
 124 SYSCTL_INT(_net_inet_tcp, OID_AUTO, keepcnt, CTLFLAG_RW, &tcp_keepcnt, 0,
 125     "Number of keepalive probes to send");
 126
 127         /* max idle probes */
 128 int     tcp_maxpersistidle;
 129
 130 static int      tcp_rexmit_drop_options = 0;
 131 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rexmit_drop_options, CTLFLAG_RW,
 132     &tcp_rexmit_drop_options, 0,
 133     "Drop TCP options from 3rd and later retransmitted SYN");
 134
 135 static VNET_DEFINE(int, tcp_pmtud_blackhole_detect);
 136 #define V_tcp_pmtud_blackhole_detect    VNET(tcp_pmtud_blackhole_detect)
 137 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_detection,
 138     CTLFLAG_RW|CTLFLAG_VNET,
 139     &VNET_NAME(tcp_pmtud_blackhole_detect), 0,
 140     "Path MTU Discovery Black Hole Detection Enabled");
 141
 142 static VNET_DEFINE(int, tcp_pmtud_blackhole_activated);
 143 #define V_tcp_pmtud_blackhole_activated \
 144     VNET(tcp_pmtud_blackhole_activated)
 145 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_activated,
 146     CTLFLAG_RD|CTLFLAG_VNET,
 147     &VNET_NAME(tcp_pmtud_blackhole_activated), 0,
 148     "Path MTU Discovery Black Hole Detection, Activation Count");
 149
 150 static VNET_DEFINE(int, tcp_pmtud_blackhole_activated_min_mss);
 151 #define V_tcp_pmtud_blackhole_activated_min_mss \
 152     VNET(tcp_pmtud_blackhole_activated_min_mss)
 153 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_activated_min_mss,
 154     CTLFLAG_RD|CTLFLAG_VNET,
 155     &VNET_NAME(tcp_pmtud_blackhole_activated_min_mss), 0,
 156     "Path MTU Discovery Black Hole Detection, Activation Count at min MSS");
 157
 158 static VNET_DEFINE(int, tcp_pmtud_blackhole_failed);
 159 #define V_tcp_pmtud_blackhole_failed    VNET(tcp_pmtud_blackhole_failed)
 160 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_failed,
 161     CTLFLAG_RD|CTLFLAG_VNET,
 162     &VNET_NAME(tcp_pmtud_blackhole_failed), 0,
 163     "Path MTU Discovery Black Hole Detection, Failure Count");
 164
 165 #ifdef INET
 166 static VNET_DEFINE(int, tcp_pmtud_blackhole_mss) = 1200;
 167 #define V_tcp_pmtud_blackhole_mss       VNET(tcp_pmtud_blackhole_mss)
 168 SYSCTL_INT(_net_inet_tcp, OID_AUTO, pmtud_blackhole_mss,
 169     CTLFLAG_RW|CTLFLAG_VNET,
 170     &VNET_NAME(tcp_pmtud_blackhole_mss), 0,
 171     "Path MTU Discovery Black Hole Detection lowered MSS");
 172 #endif
 173
 174 #ifdef INET6
 175 static VNET_DEFINE(int, tcp_v6pmtud_blackhole_mss) = 1220;
 176 #define V_tcp_v6pmtud_blackhole_mss     VNET(tcp_v6pmtud_blackhole_mss)
 177 SYSCTL_INT(_net_inet_tcp, OID_AUTO, v6pmtud_blackhole_mss,
 178     CTLFLAG_RW|CTLFLAG_VNET,
 179     &VNET_NAME(tcp_v6pmtud_blackhole_mss), 0,
 180     "Path MTU Discovery IPv6 Black Hole Detection lowered MSS");
 181 #endif
 182
 183 #ifdef  RSS
 184 static int      per_cpu_timers = 1;
 185 #else
 186 static int      per_cpu_timers = 0;
 187 #endif
 188 SYSCTL_INT(_net_inet_tcp, OID_AUTO, per_cpu_timers, CTLFLAG_RW,
 189     &per_cpu_timers , 0, "run tcp timers on all cpus");
 190
 191 #if 0
 192 #define INP_CPU(inp)    (per_cpu_timers ? (!CPU_ABSENT(((inp)->inp_flowid % (mp_maxid+1))) ? \
 193                 ((inp)->inp_flowid % (mp_maxid+1)) : curcpu) : 0)
 194 #endif
 195
 196 /*
 197  * Map the given inp to a CPU id.
 198  *
 199  * This queries RSS if it's compiled in, else it defaults to the current
 200  * CPU ID.
 201  */
 202 static inline int
 203 inp_to_cpuid(struct inpcb *inp)
 204 {
 205         u_int cpuid;
 206
 207 #ifdef  RSS
 208         if (per_cpu_timers) {
 209                 cpuid = rss_hash2cpuid(inp->inp_flowid, inp->inp_flowtype);
 210                 if (cpuid == NETISR_CPUID_NONE)
 211                         return (curcpu);        /* XXX */
 212                 else
 213                         return (cpuid);
 214         }
 215 #else
 216         /* Legacy, pre-RSS behaviour */
 217         if (per_cpu_timers) {
 218                 /*
 219                  * We don't have a flowid -> cpuid mapping, so cheat and
 220                  * just map unknown cpuids to curcpu.  Not the best, but
 221                  * apparently better than defaulting to swi 0.
 222                  */
 223                 cpuid = inp->inp_flowid % (mp_maxid + 1);
 224                 if (! CPU_ABSENT(cpuid))
 225                         return (cpuid);
 226                 return (curcpu);
 227         }
 228 #endif
 229         /* Default for RSS and non-RSS - cpuid 0 */
 230         else {
 231                 return (0);
 232         }
 233 }
 234
 235 /*
 236  * Tcp protocol timeout routine called every 500 ms.
 237  * Updates timestamps used for TCP
 238  * causes finite state machine actions if timers expire.
 239  */
 240 void
 241 tcp_slowtimo(void)
 242 {
 243         VNET_ITERATOR_DECL(vnet_iter);
 244
 245         VNET_LIST_RLOCK_NOSLEEP();
 246         VNET_FOREACH(vnet_iter) {
 247                 CURVNET_SET(vnet_iter);
 248                 (void) tcp_tw_2msl_scan(0);
 249                 CURVNET_RESTORE();
 250         }
 251         VNET_LIST_RUNLOCK_NOSLEEP();
 252 }
 253
 254 int     tcp_syn_backoff[TCP_MAXRXTSHIFT + 1] =
 255     { 1, 1, 1, 1, 1, 2, 4, 8, 16, 32, 64, 64, 64 };
 256
 257 int     tcp_backoff[TCP_MAXRXTSHIFT + 1] =
 258     { 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 512, 512, 512 };
 259
 260 static int tcp_totbackoff = 2559;       /* sum of tcp_backoff[] */
 261
 262 /*
 263  * TCP timer processing.
 264  */
 265
 266 void
 267 tcp_timer_delack(void *xtp)
 268 {
 269         struct tcpcb *tp = xtp;
 270         struct inpcb *inp;
 271         CURVNET_SET(tp->t_vnet);
 272
 273         inp = tp->t_inpcb;
 274         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 275         INP_WLOCK(inp);
 276         if (callout_pending(&tp->t_timers->tt_delack) ||
 277             !callout_active(&tp->t_timers->tt_delack)) {
 278                 INP_WUNLOCK(inp);
 279                 CURVNET_RESTORE();
 280                 return;
 281         }
 282         callout_deactivate(&tp->t_timers->tt_delack);
 283         if ((inp->inp_flags & INP_DROPPED) != 0) {
 284                 INP_WUNLOCK(inp);
 285                 CURVNET_RESTORE();
 286                 return;
 287         }
 288         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
 289                 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
 290         KASSERT((tp->t_timers->tt_flags & TT_DELACK) != 0,
 291                 ("%s: tp %p delack callout should be running", __func__, tp));
 292
 293         tp->t_flags |= TF_ACKNOW;
 294         TCPSTAT_INC(tcps_delack);
 295         (void) tp->t_fb->tfb_tcp_output(tp);
 296         INP_WUNLOCK(inp);
 297         CURVNET_RESTORE();
 298 }
 299
 300 void
 301 tcp_timer_2msl(void *xtp)
 302 {
 303         struct tcpcb *tp = xtp;
 304         struct inpcb *inp;
 305         CURVNET_SET(tp->t_vnet);
 306 #ifdef TCPDEBUG
 307         int ostate;
 308
 309         ostate = tp->t_state;
 310 #endif
 311         INP_INFO_RLOCK(&V_tcbinfo);
 312         inp = tp->t_inpcb;
 313         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 314         INP_WLOCK(inp);
 315         tcp_free_sackholes(tp);
 316         if (callout_pending(&tp->t_timers->tt_2msl) ||
 317             !callout_active(&tp->t_timers->tt_2msl)) {
 318                 INP_WUNLOCK(tp->t_inpcb);
 319                 INP_INFO_RUNLOCK(&V_tcbinfo);
 320                 CURVNET_RESTORE();
 321                 return;
 322         }
 323         callout_deactivate(&tp->t_timers->tt_2msl);
 324         if ((inp->inp_flags & INP_DROPPED) != 0) {
 325                 INP_WUNLOCK(inp);
 326                 INP_INFO_RUNLOCK(&V_tcbinfo);
 327                 CURVNET_RESTORE();
 328                 return;
 329         }
 330         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
 331                 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
 332         KASSERT((tp->t_timers->tt_flags & TT_2MSL) != 0,
 333                 ("%s: tp %p 2msl callout should be running", __func__, tp));
 334         /*
 335          * 2 MSL timeout in shutdown went off.  If we're closed but
 336          * still waiting for peer to close and connection has been idle
 337          * too long delete connection control block.  Otherwise, check
 338          * again in a bit.
 339          *
 340          * If in TIME_WAIT state just ignore as this timeout is handled in
 341          * tcp_tw_2msl_scan().
 342          *
 343          * If fastrecycle of FIN_WAIT_2, in FIN_WAIT_2 and receiver has closed,
 344          * there's no point in hanging onto FIN_WAIT_2 socket. Just close it.
 345          * Ignore fact that there were recent incoming segments.
 346          */
 347         if ((inp->inp_flags & INP_TIMEWAIT) != 0) {
 348                 INP_WUNLOCK(inp);
 349                 INP_INFO_RUNLOCK(&V_tcbinfo);
 350                 CURVNET_RESTORE();
 351                 return;
 352         }
 353         if (tcp_fast_finwait2_recycle && tp->t_state == TCPS_FIN_WAIT_2 &&
 354             tp->t_inpcb && tp->t_inpcb->inp_socket &&
 355             (tp->t_inpcb->inp_socket->so_rcv.sb_state & SBS_CANTRCVMORE)) {
 356                 TCPSTAT_INC(tcps_finwait2_drops);
 357                 tp = tcp_close(tp);
 358         } else {
 359                 if (ticks - tp->t_rcvtime <= TP_MAXIDLE(tp)) {
 360                         if (!callout_reset(&tp->t_timers->tt_2msl,
 361                            TP_KEEPINTVL(tp), tcp_timer_2msl, tp)) {
 362                                 tp->t_timers->tt_flags &= ~TT_2MSL_RST;
 363                         }
 364                 } else
 365                        tp = tcp_close(tp);
 366        }
 367
 368 #ifdef TCPDEBUG
 369         if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
 370                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 371                           PRU_SLOWTIMO);
 372 #endif
 373         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 374
 375         if (tp != NULL)
 376                 INP_WUNLOCK(inp);
 377         INP_INFO_RUNLOCK(&V_tcbinfo);
 378         CURVNET_RESTORE();
 379 }
 380
 381 void
 382 tcp_timer_keep(void *xtp)
 383 {
 384         struct tcpcb *tp = xtp;
 385         struct tcptemp *t_template;
 386         struct inpcb *inp;
 387         CURVNET_SET(tp->t_vnet);
 388 #ifdef TCPDEBUG
 389         int ostate;
 390
 391         ostate = tp->t_state;
 392 #endif
 393         INP_INFO_RLOCK(&V_tcbinfo);
 394         inp = tp->t_inpcb;
 395         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 396         INP_WLOCK(inp);
 397         if (callout_pending(&tp->t_timers->tt_keep) ||
 398             !callout_active(&tp->t_timers->tt_keep)) {
 399                 INP_WUNLOCK(inp);
 400                 INP_INFO_RUNLOCK(&V_tcbinfo);
 401                 CURVNET_RESTORE();
 402                 return;
 403         }
 404         callout_deactivate(&tp->t_timers->tt_keep);
 405         if ((inp->inp_flags & INP_DROPPED) != 0) {
 406                 INP_WUNLOCK(inp);
 407                 INP_INFO_RUNLOCK(&V_tcbinfo);
 408                 CURVNET_RESTORE();
 409                 return;
 410         }
 411         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
 412                 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
 413         KASSERT((tp->t_timers->tt_flags & TT_KEEP) != 0,
 414                 ("%s: tp %p keep callout should be running", __func__, tp));
 415         /*
 416          * Keep-alive timer went off; send something
 417          * or drop connection if idle for too long.
 418          */
 419         TCPSTAT_INC(tcps_keeptimeo);
 420         if (tp->t_state < TCPS_ESTABLISHED)
 421                 goto dropit;
 422         if ((always_keepalive || inp->inp_socket->so_options & SO_KEEPALIVE) &&
 423             tp->t_state <= TCPS_CLOSING) {
 424                 if (ticks - tp->t_rcvtime >= TP_KEEPIDLE(tp) + TP_MAXIDLE(tp))
 425                         goto dropit;
 426                 /*
 427                  * Send a packet designed to force a response
 428                  * if the peer is up and reachable:
 429                  * either an ACK if the connection is still alive,
 430                  * or an RST if the peer has closed the connection
 431                  * due to timeout or reboot.
 432                  * Using sequence number tp->snd_una-1
 433                  * causes the transmitted zero-length segment
 434                  * to lie outside the receive window;
 435                  * by the protocol spec, this requires the
 436                  * correspondent TCP to respond.
 437                  */
 438                 TCPSTAT_INC(tcps_keepprobe);
 439                 t_template = tcpip_maketemplate(inp);
 440                 if (t_template) {
 441                         tcp_respond(tp, t_template->tt_ipgen,
 442                                     &t_template->tt_t, (struct mbuf *)NULL,
 443                                     tp->rcv_nxt, tp->snd_una - 1, 0);
 444                         free(t_template, M_TEMP);
 445                 }
 446                 if (!callout_reset(&tp->t_timers->tt_keep, TP_KEEPINTVL(tp),
 447                     tcp_timer_keep, tp)) {
 448                         tp->t_timers->tt_flags &= ~TT_KEEP_RST;
 449                 }
 450         } else if (!callout_reset(&tp->t_timers->tt_keep, TP_KEEPIDLE(tp),
 451                     tcp_timer_keep, tp)) {
 452                         tp->t_timers->tt_flags &= ~TT_KEEP_RST;
 453                 }
 454
 455 #ifdef TCPDEBUG
 456         if (inp->inp_socket->so_options & SO_DEBUG)
 457                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 458                           PRU_SLOWTIMO);
 459 #endif
 460         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 461         INP_WUNLOCK(inp);
 462         INP_INFO_RUNLOCK(&V_tcbinfo);
 463         CURVNET_RESTORE();
 464         return;
 465
 466 dropit:
 467         TCPSTAT_INC(tcps_keepdrops);
 468         tp = tcp_drop(tp, ETIMEDOUT);
 469
 470 #ifdef TCPDEBUG
 471         if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
 472                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 473                           PRU_SLOWTIMO);
 474 #endif
 475         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 476         if (tp != NULL)
 477                 INP_WUNLOCK(tp->t_inpcb);
 478         INP_INFO_RUNLOCK(&V_tcbinfo);
 479         CURVNET_RESTORE();
 480 }
 481
 482 void
 483 tcp_timer_persist(void *xtp)
 484 {
 485         struct tcpcb *tp = xtp;
 486         struct inpcb *inp;
 487         CURVNET_SET(tp->t_vnet);
 488 #ifdef TCPDEBUG
 489         int ostate;
 490
 491         ostate = tp->t_state;
 492 #endif
 493         INP_INFO_RLOCK(&V_tcbinfo);
 494         inp = tp->t_inpcb;
 495         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 496         INP_WLOCK(inp);
 497         if (callout_pending(&tp->t_timers->tt_persist) ||
 498             !callout_active(&tp->t_timers->tt_persist)) {
 499                 INP_WUNLOCK(inp);
 500                 INP_INFO_RUNLOCK(&V_tcbinfo);
 501                 CURVNET_RESTORE();
 502                 return;
 503         }
 504         callout_deactivate(&tp->t_timers->tt_persist);
 505         if ((inp->inp_flags & INP_DROPPED) != 0) {
 506                 INP_WUNLOCK(inp);
 507                 INP_INFO_RUNLOCK(&V_tcbinfo);
 508                 CURVNET_RESTORE();
 509                 return;
 510         }
 511         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
 512                 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
 513         KASSERT((tp->t_timers->tt_flags & TT_PERSIST) != 0,
 514                 ("%s: tp %p persist callout should be running", __func__, tp));
 515         /*
 516          * Persistance timer into zero window.
 517          * Force a byte to be output, if possible.
 518          */
 519         TCPSTAT_INC(tcps_persisttimeo);
 520         /*
 521          * Hack: if the peer is dead/unreachable, we do not
 522          * time out if the window is closed.  After a full
 523          * backoff, drop the connection if the idle time
 524          * (no responses to probes) reaches the maximum
 525          * backoff that we would use if retransmitting.
 526          */
 527         if (tp->t_rxtshift == TCP_MAXRXTSHIFT &&
 528             (ticks - tp->t_rcvtime >= tcp_maxpersistidle ||
 529              ticks - tp->t_rcvtime >= TCP_REXMTVAL(tp) * tcp_totbackoff)) {
 530                 TCPSTAT_INC(tcps_persistdrop);
 531                 tp = tcp_drop(tp, ETIMEDOUT);
 532                 goto out;
 533         }
 534         /*
 535          * If the user has closed the socket then drop a persisting
 536          * connection after a much reduced timeout.
 537          */
 538         if (tp->t_state > TCPS_CLOSE_WAIT &&
 539             (ticks - tp->t_rcvtime) >= TCPTV_PERSMAX) {
 540                 TCPSTAT_INC(tcps_persistdrop);
 541                 tp = tcp_drop(tp, ETIMEDOUT);
 542                 goto out;
 543         }
 544         tcp_setpersist(tp);
 545         tp->t_flags |= TF_FORCEDATA;
 546         (void) tp->t_fb->tfb_tcp_output(tp);
 547         tp->t_flags &= ~TF_FORCEDATA;
 548
 549 out:
 550 #ifdef TCPDEBUG
 551         if (tp != NULL && tp->t_inpcb->inp_socket->so_options & SO_DEBUG)
 552                 tcp_trace(TA_USER, ostate, tp, NULL, NULL, PRU_SLOWTIMO);
 553 #endif
 554         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 555         if (tp != NULL)
 556                 INP_WUNLOCK(inp);
 557         INP_INFO_RUNLOCK(&V_tcbinfo);
 558         CURVNET_RESTORE();
 559 }
 560
 561 void
 562 tcp_timer_rexmt(void * xtp)
 563 {
 564         struct tcpcb *tp = xtp;
 565         CURVNET_SET(tp->t_vnet);
 566         int rexmt;
 567         int headlocked;
 568         struct inpcb *inp;
 569 #ifdef TCPDEBUG
 570         int ostate;
 571
 572         ostate = tp->t_state;
 573 #endif
 574
 575         INP_INFO_RLOCK(&V_tcbinfo);
 576         inp = tp->t_inpcb;
 577         KASSERT(inp != NULL, ("%s: tp %p tp->t_inpcb == NULL", __func__, tp));
 578         INP_WLOCK(inp);
 579         if (callout_pending(&tp->t_timers->tt_rexmt) ||
 580             !callout_active(&tp->t_timers->tt_rexmt)) {
 581                 INP_WUNLOCK(inp);
 582                 INP_INFO_RUNLOCK(&V_tcbinfo);
 583                 CURVNET_RESTORE();
 584                 return;
 585         }
 586         callout_deactivate(&tp->t_timers->tt_rexmt);
 587         if ((inp->inp_flags & INP_DROPPED) != 0) {
 588                 INP_WUNLOCK(inp);
 589                 INP_INFO_RUNLOCK(&V_tcbinfo);
 590                 CURVNET_RESTORE();
 591                 return;
 592         }
 593         KASSERT((tp->t_timers->tt_flags & TT_STOPPED) == 0,
 594                 ("%s: tp %p tcpcb can't be stopped here", __func__, tp));
 595         KASSERT((tp->t_timers->tt_flags & TT_REXMT) != 0,
 596                 ("%s: tp %p rexmt callout should be running", __func__, tp));
 597         tcp_free_sackholes(tp);
 598         /*
 599          * Retransmission timer went off.  Message has not
 600          * been acked within retransmit interval.  Back off
 601          * to a longer retransmit interval and retransmit one segment.
 602          */
 603         if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) {
 604                 tp->t_rxtshift = TCP_MAXRXTSHIFT;
 605                 TCPSTAT_INC(tcps_timeoutdrop);
 606
 607                 tp = tcp_drop(tp, tp->t_softerror ?
 608                               tp->t_softerror : ETIMEDOUT);
 609                 headlocked = 1;
 610                 goto out;
 611         }
 612         INP_INFO_RUNLOCK(&V_tcbinfo);
 613         headlocked = 0;
 614         if (tp->t_state == TCPS_SYN_SENT) {
 615                 /*
 616                  * If the SYN was retransmitted, indicate CWND to be
 617                  * limited to 1 segment in cc_conn_init().
 618                  */
 619                 tp->snd_cwnd = 1;
 620         } else if (tp->t_rxtshift == 1) {
 621                 /*
 622                  * first retransmit; record ssthresh and cwnd so they can
 623                  * be recovered if this turns out to be a "bad" retransmit.
 624                  * A retransmit is considered "bad" if an ACK for this
 625                  * segment is received within RTT/2 interval; the assumption
 626                  * here is that the ACK was already in flight.  See
 627                  * "On Estimating End-to-End Network Path Properties" by
 628                  * Allman and Paxson for more details.
 629                  */
 630                 tp->snd_cwnd_prev = tp->snd_cwnd;
 631                 tp->snd_ssthresh_prev = tp->snd_ssthresh;
 632                 tp->snd_recover_prev = tp->snd_recover;
 633                 if (IN_FASTRECOVERY(tp->t_flags))
 634                         tp->t_flags |= TF_WASFRECOVERY;
 635                 else
 636                         tp->t_flags &= ~TF_WASFRECOVERY;
 637                 if (IN_CONGRECOVERY(tp->t_flags))
 638                         tp->t_flags |= TF_WASCRECOVERY;
 639                 else
 640                         tp->t_flags &= ~TF_WASCRECOVERY;
 641                 tp->t_badrxtwin = ticks + (tp->t_srtt >> (TCP_RTT_SHIFT + 1));
 642                 tp->t_flags |= TF_PREVVALID;
 643         } else
 644                 tp->t_flags &= ~TF_PREVVALID;
 645         TCPSTAT_INC(tcps_rexmttimeo);
 646         if ((tp->t_state == TCPS_SYN_SENT) ||
 647             (tp->t_state == TCPS_SYN_RECEIVED))
 648                 rexmt = TCPTV_RTOBASE * tcp_syn_backoff[tp->t_rxtshift];
 649         else
 650                 rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift];
 651         TCPT_RANGESET(tp->t_rxtcur, rexmt,
 652                       tp->t_rttmin, TCPTV_REXMTMAX);
 653
 654         /*
 655          * We enter the path for PLMTUD if connection is established or, if
 656          * connection is FIN_WAIT_1 status, reason for the last is that if
 657          * amount of data we send is very small, we could send it in couple of
 658          * packets and process straight to FIN. In that case we won't catch
 659          * ESTABLISHED state.
 660          */
 661         if (V_tcp_pmtud_blackhole_detect && (((tp->t_state == TCPS_ESTABLISHED))
 662             || (tp->t_state == TCPS_FIN_WAIT_1))) {
 663 #ifdef INET6
 664                 int isipv6;
 665 #endif
 666
 667                 /*
 668                  * Idea here is that at each stage of mtu probe (usually, 1448
 669                  * -> 1188 -> 524) should be given 2 chances to recover before
 670                  *  further clamping down. 'tp->t_rxtshift % 2 == 0' should
 671                  *  take care of that.
 672                  */
 673                 if (((tp->t_flags2 & (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) ==
 674                     (TF2_PLPMTU_PMTUD|TF2_PLPMTU_MAXSEGSNT)) &&
 675                     (tp->t_rxtshift >= 2 && tp->t_rxtshift % 2 == 0)) {
 676                         /*
 677                          * Enter Path MTU Black-hole Detection mechanism:
 678                          * - Disable Path MTU Discovery (IP "DF" bit).
 679                          * - Reduce MTU to lower value than what we
 680                          *   negotiated with peer.
 681                          */
 682                         /* Record that we may have found a black hole. */
 683                         tp->t_flags2 |= TF2_PLPMTU_BLACKHOLE;
 684
 685                         /* Keep track of previous MSS. */
 686                         tp->t_pmtud_saved_maxseg = tp->t_maxseg;
 687
 688                         /*
 689                          * Reduce the MSS to blackhole value or to the default
 690                          * in an attempt to retransmit.
 691                          */
 692 #ifdef INET6
 693                         isipv6 = (tp->t_inpcb->inp_vflag & INP_IPV6) ? 1 : 0;
 694                         if (isipv6 &&
 695                             tp->t_maxseg > V_tcp_v6pmtud_blackhole_mss) {
 696                                 /* Use the sysctl tuneable blackhole MSS. */
 697                                 tp->t_maxseg = V_tcp_v6pmtud_blackhole_mss;
 698                                 V_tcp_pmtud_blackhole_activated++;
 699                         } else if (isipv6) {
 700                                 /* Use the default MSS. */
 701                                 tp->t_maxseg = V_tcp_v6mssdflt;
 702                                 /*
 703                                  * Disable Path MTU Discovery when we switch to
 704                                  * minmss.
 705                                  */
 706                                 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
 707                                 V_tcp_pmtud_blackhole_activated_min_mss++;
 708                         }
 709 #endif
 710 #if defined(INET6) && defined(INET)
 711                         else
 712 #endif
 713 #ifdef INET
 714                         if (tp->t_maxseg > V_tcp_pmtud_blackhole_mss) {
 715                                 /* Use the sysctl tuneable blackhole MSS. */
 716                                 tp->t_maxseg = V_tcp_pmtud_blackhole_mss;
 717                                 V_tcp_pmtud_blackhole_activated++;
 718                         } else {
 719                                 /* Use the default MSS. */
 720                                 tp->t_maxseg = V_tcp_mssdflt;
 721                                 /*
 722                                  * Disable Path MTU Discovery when we switch to
 723                                  * minmss.
 724                                  */
 725                                 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD;
 726                                 V_tcp_pmtud_blackhole_activated_min_mss++;
 727                         }
 728 #endif
 729                         /*
 730                          * Reset the slow-start flight size
 731                          * as it may depend on the new MSS.
 732                          */
 733                         if (CC_ALGO(tp)->conn_init != NULL)
 734                                 CC_ALGO(tp)->conn_init(tp->ccv);
 735                 } else {
 736                         /*
 737                          * If further retransmissions are still unsuccessful
 738                          * with a lowered MTU, maybe this isn't a blackhole and
 739                          * we restore the previous MSS and blackhole detection
 740                          * flags.
 741                          * The limit '6' is determined by giving each probe
 742                          * stage (1448, 1188, 524) 2 chances to recover.
 743                          */
 744                         if ((tp->t_flags2 & TF2_PLPMTU_BLACKHOLE) &&
 745                             (tp->t_rxtshift > 6)) {
 746                                 tp->t_flags2 |= TF2_PLPMTU_PMTUD;
 747                                 tp->t_flags2 &= ~TF2_PLPMTU_BLACKHOLE;
 748                                 tp->t_maxseg = tp->t_pmtud_saved_maxseg;
 749                                 V_tcp_pmtud_blackhole_failed++;
 750                                 /*
 751                                  * Reset the slow-start flight size as it
 752                                  * may depend on the new MSS.
 753                                  */
 754                                 if (CC_ALGO(tp)->conn_init != NULL)
 755                                         CC_ALGO(tp)->conn_init(tp->ccv);
 756                         }
 757                 }
 758         }
 759
 760         /*
 761          * Disable RFC1323 and SACK if we haven't got any response to
 762          * our third SYN to work-around some broken terminal servers
 763          * (most of which have hopefully been retired) that have bad VJ
 764          * header compression code which trashes TCP segments containing
 765          * unknown-to-them TCP options.
 766          */
 767         if (tcp_rexmit_drop_options && (tp->t_state == TCPS_SYN_SENT) &&
 768             (tp->t_rxtshift == 3))
 769                 tp->t_flags &= ~(TF_REQ_SCALE|TF_REQ_TSTMP|TF_SACK_PERMIT);
 770         /*
 771          * If we backed off this far, our srtt estimate is probably bogus.
 772          * Clobber it so we'll take the next rtt measurement as our srtt;
 773          * move the current srtt into rttvar to keep the current
 774          * retransmit times until then.
 775          */
 776         if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) {
 777 #ifdef INET6
 778                 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0)
 779                         in6_losing(tp->t_inpcb);
 780 #endif
 781                 tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT);
 782                 tp->t_srtt = 0;
 783         }
 784         tp->snd_nxt = tp->snd_una;
 785         tp->snd_recover = tp->snd_max;
 786         /*
 787          * Force a segment to be sent.
 788          */
 789         tp->t_flags |= TF_ACKNOW;
 790         /*
 791          * If timing a segment in this window, stop the timer.
 792          */
 793         tp->t_rtttime = 0;
 794
 795         cc_cong_signal(tp, NULL, CC_RTO);
 796
 797         (void) tp->t_fb->tfb_tcp_output(tp);
 798
 799 out:
 800 #ifdef TCPDEBUG
 801         if (tp != NULL && (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
 802                 tcp_trace(TA_USER, ostate, tp, (void *)0, (struct tcphdr *)0,
 803                           PRU_SLOWTIMO);
 804 #endif
 805         TCP_PROBE2(debug__user, tp, PRU_SLOWTIMO);
 806         if (tp != NULL)
 807                 INP_WUNLOCK(inp);
 808         if (headlocked)
 809                 INP_INFO_RUNLOCK(&V_tcbinfo);
 810         CURVNET_RESTORE();
 811 }
 812
 813 void
 814 tcp_timer_activate(struct tcpcb *tp, uint32_t timer_type, u_int delta)
 815 {
 816         struct callout *t_callout;
 817         timeout_t *f_callout;
 818         struct inpcb *inp = tp->t_inpcb;
 819         int cpu = inp_to_cpuid(inp);
 820         uint32_t f_reset;
 821
 822 #ifdef TCP_OFFLOAD
 823         if (tp->t_flags & TF_TOE)
 824                 return;
 825 #endif
 826
 827         if (tp->t_timers->tt_flags & TT_STOPPED)
 828                 return;
 829
 830         switch (timer_type) {
 831                 case TT_DELACK:
 832                         t_callout = &tp->t_timers->tt_delack;
 833                         f_callout = tcp_timer_delack;
 834                         f_reset = TT_DELACK_RST;
 835                         break;
 836                 case TT_REXMT:
 837                         t_callout = &tp->t_timers->tt_rexmt;
 838                         f_callout = tcp_timer_rexmt;
 839                         f_reset = TT_REXMT_RST;
 840                         break;
 841                 case TT_PERSIST:
 842                         t_callout = &tp->t_timers->tt_persist;
 843                         f_callout = tcp_timer_persist;
 844                         f_reset = TT_PERSIST_RST;
 845                         break;
 846                 case TT_KEEP:
 847                         t_callout = &tp->t_timers->tt_keep;
 848                         f_callout = tcp_timer_keep;
 849                         f_reset = TT_KEEP_RST;
 850                         break;
 851                 case TT_2MSL:
 852                         t_callout = &tp->t_timers->tt_2msl;
 853                         f_callout = tcp_timer_2msl;
 854                         f_reset = TT_2MSL_RST;
 855                         break;
 856                 default:
 857                         if (tp->t_fb->tfb_tcp_timer_activate) {
 858                                 tp->t_fb->tfb_tcp_timer_activate(tp, timer_type, delta);
 859                                 return;
 860                         }
 861                         panic("tp %p bad timer_type %#x", tp, timer_type);
 862                 }
 863         if (delta == 0) {
 864                 if ((tp->t_timers->tt_flags & timer_type) &&
 865                     (callout_stop(t_callout) > 0) &&
 866                     (tp->t_timers->tt_flags & f_reset)) {
 867                         tp->t_timers->tt_flags &= ~(timer_type | f_reset);
 868                 }
 869         } else {
 870                 if ((tp->t_timers->tt_flags & timer_type) == 0) {
 871                         tp->t_timers->tt_flags |= (timer_type | f_reset);
 872                         callout_reset_on(t_callout, delta, f_callout, tp, cpu);
 873                 } else {
 874                         /* Reset already running callout on the same CPU. */
 875                         if (!callout_reset(t_callout, delta, f_callout, tp)) {
 876                                 /*
 877                                  * Callout not cancelled, consider it as not
 878                                  * properly restarted. */
 879                                 tp->t_timers->tt_flags &= ~f_reset;
 880                         }
 881                 }
 882         }
 883 }
 884
 885 int
 886 tcp_timer_active(struct tcpcb *tp, uint32_t timer_type)
 887 {
 888         struct callout *t_callout;
 889
 890         switch (timer_type) {
 891                 case TT_DELACK:
 892                         t_callout = &tp->t_timers->tt_delack;
 893                         break;
 894                 case TT_REXMT:
 895                         t_callout = &tp->t_timers->tt_rexmt;
 896                         break;
 897                 case TT_PERSIST:
 898                         t_callout = &tp->t_timers->tt_persist;
 899                         break;
 900                 case TT_KEEP:
 901                         t_callout = &tp->t_timers->tt_keep;
 902                         break;
 903                 case TT_2MSL:
 904                         t_callout = &tp->t_timers->tt_2msl;
 905                         break;
 906                 default:
 907                         if (tp->t_fb->tfb_tcp_timer_active) {
 908                                 return(tp->t_fb->tfb_tcp_timer_active(tp, timer_type));
 909                         }
 910                         panic("tp %p bad timer_type %#x", tp, timer_type);
 911                 }
 912         return callout_active(t_callout);
 913 }
 914
 915 void
 916 tcp_timer_stop(struct tcpcb *tp, uint32_t timer_type)
 917 {
 918         struct callout *t_callout;
 919         timeout_t *f_callout;
 920         uint32_t f_reset;
 921
 922         tp->t_timers->tt_flags |= TT_STOPPED;
 923
 924         switch (timer_type) {
 925                 case TT_DELACK:
 926                         t_callout = &tp->t_timers->tt_delack;
 927                         f_callout = tcp_timer_delack_discard;
 928                         f_reset = TT_DELACK_RST;
 929                         break;
 930                 case TT_REXMT:
 931                         t_callout = &tp->t_timers->tt_rexmt;
 932                         f_callout = tcp_timer_rexmt_discard;
 933                         f_reset = TT_REXMT_RST;
 934                         break;
 935                 case TT_PERSIST:
 936                         t_callout = &tp->t_timers->tt_persist;
 937                         f_callout = tcp_timer_persist_discard;
 938                         f_reset = TT_PERSIST_RST;
 939                         break;
 940                 case TT_KEEP:
 941                         t_callout = &tp->t_timers->tt_keep;
 942                         f_callout = tcp_timer_keep_discard;
 943                         f_reset = TT_KEEP_RST;
 944                         break;
 945                 case TT_2MSL:
 946                         t_callout = &tp->t_timers->tt_2msl;
 947                         f_callout = tcp_timer_2msl_discard;
 948                         f_reset = TT_2MSL_RST;
 949                         break;
 950                 default:
 951                         if (tp->t_fb->tfb_tcp_timer_stop) {
 952                                 /*
 953                                  * XXXrrs we need to look at this with the
 954                                  * stop case below (flags).
 955                                  */
 956                                 tp->t_fb->tfb_tcp_timer_stop(tp, timer_type);
 957                                 return;
 958                         }
 959                         panic("tp %p bad timer_type %#x", tp, timer_type);
 960                 }
 961
 962         if (tp->t_timers->tt_flags & timer_type) {
 963                 if ((callout_stop(t_callout) > 0) &&
 964                     (tp->t_timers->tt_flags & f_reset)) {
 965                         tp->t_timers->tt_flags &= ~(timer_type | f_reset);
 966                 } else {
 967                         /*
 968                          * Can't stop the callout, defer tcpcb actual deletion
 969                          * to the last tcp timer discard callout.
 970                          * The TT_STOPPED flag will ensure that no tcp timer
 971                          * callouts can be restarted on our behalf, and
 972                          * past this point currently running callouts waiting
 973                          * on inp lock will return right away after the
 974                          * classical check for callout reset/stop events:
 975                          * callout_pending() || !callout_active()
 976                          */
 977                         callout_reset(t_callout, 1, f_callout, tp);
 978                 }
 979         }
 980 }
 981
 982 #define ticks_to_msecs(t)       (1000*(t) / hz)
 983
 984 void
 985 tcp_timer_to_xtimer(struct tcpcb *tp, struct tcp_timer *timer,
 986     struct xtcp_timer *xtimer)
 987 {
 988         sbintime_t now;
 989
 990         bzero(xtimer, sizeof(*xtimer));
 991         if (timer == NULL)
 992                 return;
 993         now = getsbinuptime();
 994         if (callout_active(&timer->tt_delack))
 995                 xtimer->tt_delack = (timer->tt_delack.c_time - now) / SBT_1MS;
 996         if (callout_active(&timer->tt_rexmt))
 997                 xtimer->tt_rexmt = (timer->tt_rexmt.c_time - now) / SBT_1MS;
 998         if (callout_active(&timer->tt_persist))
 999                 xtimer->tt_persist = (timer->tt_persist.c_time - now) / SBT_1MS;
1000         if (callout_active(&timer->tt_keep))
1001                 xtimer->tt_keep = (timer->tt_keep.c_time - now) / SBT_1MS;
1002         if (callout_active(&timer->tt_2msl))
1003                 xtimer->tt_2msl = (timer->tt_2msl.c_time - now) / SBT_1MS;
1004         xtimer->t_rcvtime = ticks_to_msecs(ticks - tp->t_rcvtime);
1005 }