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Annotation of kernel/bsd/netinet/tcp_timer.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
        !             3:  *
        !             4:  * @APPLE_LICENSE_HEADER_START@
        !             5:  * 
        !             6:  * Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
        !             7:  * Reserved.  This file contains Original Code and/or Modifications of
        !             8:  * Original Code as defined in and that are subject to the Apple Public
        !             9:  * Source License Version 1.1 (the "License").  You may not use this file
        !            10:  * except in compliance with the License.  Please obtain a copy of the
        !            11:  * License at http://www.apple.com/publicsource and read it before using
        !            12:  * this file.
        !            13:  * 
        !            14:  * The Original Code and all software distributed under the License are
        !            15:  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
        !            16:  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
        !            17:  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
        !            18:  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
        !            19:  * License for the specific language governing rights and limitations
        !            20:  * under the License.
        !            21:  * 
        !            22:  * @APPLE_LICENSE_HEADER_END@
        !            23:  */
        !            24: 
        !            25: /* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
        !            26: /*
        !            27:  * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995
        !            28:  *     The Regents of the University of California.  All rights reserved.
        !            29:  *
        !            30:  * Redistribution and use in source and binary forms, with or without
        !            31:  * modification, are permitted provided that the following conditions
        !            32:  * are met:
        !            33:  * 1. Redistributions of source code must retain the above copyright
        !            34:  *    notice, this list of conditions and the following disclaimer.
        !            35:  * 2. Redistributions in binary form must reproduce the above copyright
        !            36:  *    notice, this list of conditions and the following disclaimer in the
        !            37:  *    documentation and/or other materials provided with the distribution.
        !            38:  * 3. All advertising materials mentioning features or use of this software
        !            39:  *    must display the following acknowledgement:
        !            40:  *     This product includes software developed by the University of
        !            41:  *     California, Berkeley and its contributors.
        !            42:  * 4. Neither the name of the University nor the names of its contributors
        !            43:  *    may be used to endorse or promote products derived from this software
        !            44:  *    without specific prior written permission.
        !            45:  *
        !            46:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
        !            47:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
        !            48:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
        !            49:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
        !            50:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
        !            51:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
        !            52:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
        !            53:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
        !            54:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
        !            55:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
        !            56:  * SUCH DAMAGE.
        !            57:  *
        !            58:  *     @(#)tcp_timer.c 8.2 (Berkeley) 5/24/95
        !            59:  */
        !            60: 
        !            61: #ifndef TUBA_INCLUDE
        !            62: #include <sys/param.h>
        !            63: #include <sys/systm.h>
        !            64: #include <sys/malloc.h>
        !            65: #include <sys/mbuf.h>
        !            66: #include <sys/socket.h>
        !            67: #include <sys/socketvar.h>
        !            68: #include <sys/protosw.h>
        !            69: #include <sys/errno.h>
        !            70: 
        !            71: #include <net/if.h>
        !            72: #include <net/route.h>
        !            73: 
        !            74: #include <netinet/in.h>
        !            75: #include <netinet/in_systm.h>
        !            76: #include <netinet/ip.h>
        !            77: #include <netinet/in_pcb.h>
        !            78: #include <netinet/ip_var.h>
        !            79: #include <netinet/tcp.h>
        !            80: #include <netinet/tcp_fsm.h>
        !            81: #include <netinet/tcp_seq.h>
        !            82: #include <netinet/tcp_timer.h>
        !            83: #include <netinet/tcp_var.h>
        !            84: #include <netinet/tcpip.h>
        !            85: 
        !            86: #include <kern/kdebug.h>
        !            87: 
        !            88: #if KDEBUG
        !            89: 
        !            90: #define DBG_FNC_TCP_FAST       NETDBG_CODE(DBG_NETTCP, (5 << 8))
        !            91: #define DBG_FNC_TCP_SLOW       NETDBG_CODE(DBG_NETTCP, (5 << 8) | 1)
        !            92: 
        !            93: #endif
        !            94: 
        !            95: int    tcp_keepidle = TCPTV_KEEP_IDLE;
        !            96: int    tcp_keepintvl = TCPTV_KEEPINTVL;
        !            97: int    tcp_keepcnt = TCPTV_KEEPCNT;            /* max idle probes */
        !            98: int    tcp_maxpersistidle = TCPTV_KEEP_IDLE;   /* max idle time in persist */
        !            99: int    tcp_maxidle;
        !           100: #else /* TUBA_INCLUDE */
        !           101: 
        !           102: extern int tcp_maxpersistidle;
        !           103: #endif /* TUBA_INCLUDE */
        !           104: 
        !           105: extern struct  inpcb   *tcp_hash_array[];
        !           106: 
        !           107: struct inpcb   time_wait_slots[N_TIME_WAIT_SLOTS];
        !           108: int            cur_tw_slot = 0;
        !           109: 
        !           110: #if DELACK_BITMASK_ON
        !           111: u_long         delack_bitmask[N_TCP_HASH_ELEMENTS / 32];
        !           112: u_long         current_active_connections = 0;
        !           113: u_long         last_active_conn_count = 0;
        !           114: 
        !           115: #endif
        !           116: 
        !           117: void   add_to_time_wait(tp) 
        !           118:        struct tcpcb    *tp;
        !           119: {
        !           120:        int             tw_slot;
        !           121: 
        !           122:        remque((queue_t) tp->t_inpcb);
        !           123: 
        !           124:        if (tp->t_timer[TCPT_2MSL] == 0) 
        !           125:            tp->t_timer[TCPT_2MSL] = 1;
        !           126:        else 
        !           127:            if (tp->t_timer[TCPT_2MSL] >= N_TIME_WAIT_SLOTS)
        !           128:                tp->t_timer[TCPT_2MSL] = N_TIME_WAIT_SLOTS -1;
        !           129: 
        !           130:        tw_slot = tp->t_timer[TCPT_2MSL] - 1 + cur_tw_slot; 
        !           131: 
        !           132:        if (tw_slot >= N_TIME_WAIT_SLOTS) 
        !           133:                tw_slot -=  N_TIME_WAIT_SLOTS; 
        !           134: 
        !           135:        insque((queue_t) tp->t_inpcb, (queue_t) &time_wait_slots[tw_slot]);
        !           136: 
        !           137: }
        !           138: 
        !           139: 
        !           140: 
        !           141: 
        !           142: /*
        !           143:  * Fast timeout routine for processing delayed acks
        !           144:  */
        !           145: void
        !           146: tcp_fasttimo()
        !           147: {
        !           148:     register struct inpcb *inp;
        !           149:     register struct tcpcb *tp;
        !           150: 
        !           151: #if DELACK_BITMASK_ON
        !           152:     register u_long                    i,j;
        !           153:     register u_long                    temp_mask;
        !           154:     register u_long                    elem_base = 0;
        !           155: #endif
        !           156:     int s = splnet();
        !           157: 
        !           158: 
        !           159: #if KDEBUG
        !           160:     register int checked = 0;
        !           161: #endif
        !           162:     KERNEL_DEBUG(DBG_FNC_TCP_FAST | DBG_FUNC_START, 0,0,0,0,0);
        !           163: 
        !           164: #if DELACK_BITMASK_ON
        !           165: 
        !           166:     if ((current_active_connections > DELACK_BITMASK_THRESH) &&
        !           167:        (last_active_conn_count > DELACK_BITMASK_THRESH)) {
        !           168:        for (i=0; i < (N_TCP_HASH_ELEMENTS / 32); i++) {
        !           169:            if (delack_bitmask[i]) {
        !           170:                temp_mask = 1;
        !           171:                for (j=0; j < 32; j++) {
        !           172:                    if (temp_mask & delack_bitmask[i]) {
        !           173:                        inp = tcp_hash_array[elem_base + j];
        !           174:                        for (; inp != 0; inp = inp->hash_next) {
        !           175: #if KDEBUG
        !           176:                            checked++;
        !           177: #endif
        !           178:                            if ((tp = (struct tcpcb *)inp->inp_ppcb) && (tp->t_flags & TF_DELACK)) {
        !           179:                                tp->t_flags &= ~TF_DELACK;
        !           180:                                tp->t_flags |= TF_ACKNOW;
        !           181:                                tcpstat.tcps_delack++;
        !           182:                                (void) tcp_output(tp);
        !           183:                            }
        !           184:                        }
        !           185:                    }
        !           186:                    temp_mask <<=  1;
        !           187:                }
        !           188:                delack_bitmask[i] = 0;
        !           189:            }
        !           190:            elem_base += 32;
        !           191:        }
        !           192:     }
        !           193:     else 
        !           194: #endif
        !           195:     {
        !           196:        inp = tcb.inp_next;
        !           197:        if (inp)
        !           198:            for (; inp != &tcb; inp = inp->inp_next)
        !           199:                if ((tp = (struct tcpcb *)inp->inp_ppcb) &&
        !           200:                    (tp->t_flags & TF_DELACK)) {
        !           201:                    tp->t_flags &= ~TF_DELACK;
        !           202:                    tp->t_flags |= TF_ACKNOW;
        !           203:                    tcpstat.tcps_delack++;
        !           204:                    (void) tcp_output(tp);
        !           205:                }
        !           206: 
        !           207:     }
        !           208: 
        !           209: #if DELACK_BITMASK_ON
        !           210:     last_active_conn_count = current_active_connections;
        !           211: #endif
        !           212: 
        !           213:     splx(s);
        !           214: #if KDEBUG
        !           215:     KERNEL_DEBUG(DBG_FNC_TCP_FAST | DBG_FUNC_END, checked,tcpstat.tcps_delack,0,0,0);
        !           216: #endif
        !           217: }
        !           218: 
        !           219: /*
        !           220:  * Tcp protocol timeout routine called every 500 ms.
        !           221:  * Updates the timers in all active tcb's and
        !           222:  * causes finite state machine actions if timers expire.
        !           223:  */
        !           224: void
        !           225: tcp_slowtimo()
        !           226: {
        !           227:        register struct inpcb *ip, *ipnxt;
        !           228:        register struct tcpcb *tp;
        !           229:        int s = splnet();
        !           230:        register int i;
        !           231: #if KDEBUG
        !           232:        register int checked = 0;
        !           233: #endif
        !           234:        KERNEL_DEBUG(DBG_FNC_TCP_SLOW | DBG_FUNC_START, 0,0,0,0,0);
        !           235: 
        !           236:        tcp_maxidle = tcp_keepcnt * tcp_keepintvl;
        !           237:        /*
        !           238:         * Search through tcb's and update active timers.
        !           239:         */
        !           240:        if (ip = tcb.inp_next) {
        !           241:          for (; ip != &tcb; ip = ipnxt) {
        !           242: #if KDEBUG
        !           243:                checked++;
        !           244: #endif
        !           245:                ipnxt = ip->inp_next;
        !           246:                tp = intotcpcb(ip);
        !           247:                if (tp == 0 || tp->t_state == TCPS_LISTEN)
        !           248:                    continue;
        !           249:                for (i = 0; i < TCPT_NTIMERS; i++) {
        !           250:                    if (tp->t_timer[i] && --tp->t_timer[i] == 0) {
        !           251:                        (void) tcp_usrreq(tp->t_inpcb->inp_socket,
        !           252:                                          PRU_SLOWTIMO, (struct mbuf *)0,
        !           253:                                          (struct mbuf *)i, (struct mbuf *)0);
        !           254:                        if (ipnxt->inp_prev != ip)
        !           255:                            goto tpgone;
        !           256:                    }
        !           257:                }
        !           258:                tp->t_idle++;
        !           259:                if (tp->t_rtt)
        !           260:                    tp->t_rtt++;
        !           261:            tpgone:
        !           262:                ;
        !           263:          }
        !           264:        }
        !           265: #if KDEBUG
        !           266:        KERNEL_DEBUG(DBG_FNC_TCP_SLOW | DBG_FUNC_NONE, checked,0,0,0,0);
        !           267: 
        !           268:        checked = 0;
        !           269: #endif
        !           270:        /*
        !           271:         * Process the items in the current time-wait slot
        !           272:         */
        !           273: 
        !           274:        for (ip = time_wait_slots[cur_tw_slot].inp_next;
        !           275:             ip != &time_wait_slots[cur_tw_slot];
        !           276:             ip = ipnxt)
        !           277:        {
        !           278: #if KDEBUG
        !           279:                checked++;
        !           280: #endif
        !           281:                ipnxt = ip->inp_next;
        !           282:                tp = intotcpcb(ip);
        !           283:                tp->t_timer[TCPT_2MSL] = 0;
        !           284:                (void) tcp_usrreq(ip->inp_socket,
        !           285:                                  PRU_SLOWTIMO, (struct mbuf *)0,
        !           286:                                  (struct mbuf *) TCPT_2MSL, (struct mbuf *)0);
        !           287:        }
        !           288: 
        !           289:        time_wait_slots[cur_tw_slot].inp_next = &time_wait_slots[cur_tw_slot];
        !           290:        time_wait_slots[cur_tw_slot].inp_prev = &time_wait_slots[cur_tw_slot];
        !           291:        if (++cur_tw_slot >= N_TIME_WAIT_SLOTS)
        !           292:                cur_tw_slot = 0;
        !           293: 
        !           294:        tcp_iss += TCP_ISSINCR/PR_SLOWHZ;               /* increment iss */
        !           295: #ifdef TCP_COMPAT_42
        !           296:        if ((int)tcp_iss < 0)
        !           297:                tcp_iss = TCP_ISSINCR;                  /* XXX */
        !           298: #endif
        !           299:        tcp_now++;                                      /* for timestamps */
        !           300:        splx(s);
        !           301: 
        !           302: #if KDEBUG
        !           303:        KERNEL_DEBUG(DBG_FNC_TCP_SLOW | DBG_FUNC_END, checked, cur_tw_slot,0,0,0);
        !           304: #endif
        !           305: }
        !           306: #ifndef TUBA_INCLUDE
        !           307: 
        !           308: /*
        !           309:  * Cancel all timers for TCP tp.
        !           310:  */
        !           311: void
        !           312: tcp_canceltimers(tp)
        !           313:        struct tcpcb *tp;
        !           314: {
        !           315:        register int i;
        !           316: 
        !           317:        for (i = 0; i < TCPT_NTIMERS; i++)
        !           318:                tp->t_timer[i] = 0;
        !           319: }
        !           320: 
        !           321: int    tcp_backoff[TCP_MAXRXTSHIFT + 1] =
        !           322:     { 1, 2, 4, 8, 16, 32, 64, 64, 64, 64, 64, 64, 64 };
        !           323: 
        !           324: int tcp_totbackoff = 511;      /* sum of tcp_backoff[] */
        !           325: 
        !           326: /*
        !           327:  * TCP timer processing.
        !           328:  */
        !           329: struct tcpcb *
        !           330: tcp_timers(tp, timer)
        !           331:        register struct tcpcb *tp;
        !           332:        int timer;
        !           333: {
        !           334:        register int rexmt;
        !           335: 
        !           336:        switch (timer) {
        !           337: 
        !           338:        /*
        !           339:         * 2 MSL timeout in shutdown went off.  If we're closed but
        !           340:         * still waiting for peer to close and connection has been idle
        !           341:         * too long, or if 2MSL time is up from TIME_WAIT, delete connection
        !           342:         * control block.  Otherwise, check again in a bit.
        !           343:         */
        !           344:        case TCPT_2MSL:
        !           345:                if (tp->t_state != TCPS_TIME_WAIT &&
        !           346:                    tp->t_idle <= tcp_maxidle) {
        !           347:                        tp->t_timer[TCPT_2MSL] = tcp_keepintvl;
        !           348: 
        !           349:                        add_to_time_wait(tp);
        !           350:                }
        !           351:                else
        !           352:                        tp = tcp_close(tp);
        !           353:                break;
        !           354: 
        !           355:        /*
        !           356:         * Retransmission timer went off.  Message has not
        !           357:         * been acked within retransmit interval.  Back off
        !           358:         * to a longer retransmit interval and retransmit one segment.
        !           359:         */
        !           360:        case TCPT_REXMT:
        !           361:                if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) {
        !           362:                        tp->t_rxtshift = TCP_MAXRXTSHIFT;
        !           363:                        tcpstat.tcps_timeoutdrop++;
        !           364:                        tp = tcp_drop(tp, tp->t_softerror ?
        !           365:                            tp->t_softerror : ETIMEDOUT);
        !           366:                        break;
        !           367:                }
        !           368:                tcpstat.tcps_rexmttimeo++;
        !           369:                rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift];
        !           370:                TCPT_RANGESET(tp->t_rxtcur, rexmt,
        !           371:                    tp->t_rttmin, TCPTV_REXMTMAX);
        !           372:                tp->t_timer[TCPT_REXMT] = tp->t_rxtcur;
        !           373:                /*
        !           374:                 * If losing, let the lower level know and try for
        !           375:                 * a better route.  Also, if we backed off this far,
        !           376:                 * our srtt estimate is probably bogus.  Clobber it
        !           377:                 * so we'll take the next rtt measurement as our srtt;
        !           378:                 * move the current srtt into rttvar to keep the current
        !           379:                 * retransmit times until then.
        !           380:                 */
        !           381:                if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) {
        !           382:                        in_losing(tp->t_inpcb);
        !           383:                        tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT);
        !           384:                        tp->t_srtt = 0;
        !           385:                }
        !           386:                tp->snd_nxt = tp->snd_una;
        !           387:                /*
        !           388:                 * If timing a segment in this window, stop the timer.
        !           389:                 */
        !           390:                tp->t_rtt = 0;
        !           391:                /*
        !           392:                 * Close the congestion window down to one segment
        !           393:                 * (we'll open it by one segment for each ack we get).
        !           394:                 * Since we probably have a window's worth of unacked
        !           395:                 * data accumulated, this "slow start" keeps us from
        !           396:                 * dumping all that data as back-to-back packets (which
        !           397:                 * might overwhelm an intermediate gateway).
        !           398:                 *
        !           399:                 * There are two phases to the opening: Initially we
        !           400:                 * open by one mss on each ack.  This makes the window
        !           401:                 * size increase exponentially with time.  If the
        !           402:                 * window is larger than the path can handle, this
        !           403:                 * exponential growth results in dropped packet(s)
        !           404:                 * almost immediately.  To get more time between 
        !           405:                 * drops but still "push" the network to take advantage
        !           406:                 * of improving conditions, we switch from exponential
        !           407:                 * to linear window opening at some threshhold size.
        !           408:                 * For a threshhold, we use half the current window
        !           409:                 * size, truncated to a multiple of the mss.
        !           410:                 *
        !           411:                 * (the minimum cwnd that will give us exponential
        !           412:                 * growth is 2 mss.  We don't allow the threshhold
        !           413:                 * to go below this.)
        !           414:                 */
        !           415:                {
        !           416:                u_int win = min(tp->snd_wnd, tp->snd_cwnd) / 2 / tp->t_maxseg;
        !           417:                if (win < 2)
        !           418:                        win = 2;
        !           419:                tp->snd_cwnd = tp->t_maxseg;
        !           420:                tp->snd_ssthresh = win * tp->t_maxseg;
        !           421:                tp->t_dupacks = 0;
        !           422:                }
        !           423:                (void) tcp_output(tp);
        !           424:                break;
        !           425: 
        !           426:        /*
        !           427:         * Persistance timer into zero window.
        !           428:         * Force a byte to be output, if possible.
        !           429:         */
        !           430:        case TCPT_PERSIST:
        !           431:                tcpstat.tcps_persisttimeo++;
        !           432:                /*
        !           433:                 * Hack: if the peer is dead/unreachable, we do not
        !           434:                 * time out if the window is closed.  After a full
        !           435:                 * backoff, drop the connection if the idle time
        !           436:                 * (no responses to probes) reaches the maximum
        !           437:                 * backoff that we would use if retransmitting.
        !           438:                 */
        !           439:                if (tp->t_rxtshift == TCP_MAXRXTSHIFT &&
        !           440:                    (tp->t_idle >= tcp_maxpersistidle ||
        !           441:                    tp->t_idle >= TCP_REXMTVAL(tp) * tcp_totbackoff)) {
        !           442:                        tcpstat.tcps_persistdrop++;
        !           443:                        tp = tcp_drop(tp, ETIMEDOUT);
        !           444:                        break;
        !           445:                }
        !           446:                tcp_setpersist(tp);
        !           447:                tp->t_force = 1;
        !           448:                (void) tcp_output(tp);
        !           449:                tp->t_force = 0;
        !           450:                break;
        !           451: 
        !           452:        /*
        !           453:         * Keep-alive timer went off; send something
        !           454:         * or drop connection if idle for too long.
        !           455:         */
        !           456:        case TCPT_KEEP:
        !           457:                tcpstat.tcps_keeptimeo++;
        !           458:                if (tp->t_state < TCPS_ESTABLISHED)
        !           459:                        goto dropit;
        !           460:                if (tp->t_inpcb->inp_socket->so_options & SO_KEEPALIVE &&
        !           461:                    tp->t_state <= TCPS_CLOSE_WAIT) {
        !           462:                        if (tp->t_idle >= tcp_keepidle + tcp_maxidle)
        !           463:                                goto dropit;
        !           464:                        /*
        !           465:                         * Send a packet designed to force a response
        !           466:                         * if the peer is up and reachable:
        !           467:                         * either an ACK if the connection is still alive,
        !           468:                         * or an RST if the peer has closed the connection
        !           469:                         * due to timeout or reboot.
        !           470:                         * Using sequence number tp->snd_una-1
        !           471:                         * causes the transmitted zero-length segment
        !           472:                         * to lie outside the receive window;
        !           473:                         * by the protocol spec, this requires the
        !           474:                         * correspondent TCP to respond.
        !           475:                         */
        !           476:                        tcpstat.tcps_keepprobe++;
        !           477: #ifdef TCP_COMPAT_42
        !           478:                        /*
        !           479:                         * The keepalive packet must have nonzero length
        !           480:                         * to get a 4.2 host to respond.
        !           481:                         */
        !           482:                        tcp_respond(tp, tp->t_template, (struct mbuf *)NULL,
        !           483:                            tp->rcv_nxt - 1, tp->snd_una - 1, 0);
        !           484: #else
        !           485:                        tcp_respond(tp, tp->t_template, (struct mbuf *)NULL,
        !           486:                            tp->rcv_nxt, tp->snd_una - 1, 0);
        !           487: #endif
        !           488:                        tp->t_timer[TCPT_KEEP] = tcp_keepintvl;
        !           489:                } else
        !           490:                        tp->t_timer[TCPT_KEEP] = tcp_keepidle;
        !           491:                break;
        !           492:        dropit:
        !           493:                tcpstat.tcps_keepdrops++;
        !           494:                tp = tcp_drop(tp, ETIMEDOUT);
        !           495:                break;
        !           496:        }
        !           497:        return (tp);
        !           498: }
        !           499: #endif /* TUBA_INCLUDE */

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