18b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project/* 28b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * Copyright (c) 1982, 1986, 1988, 1990, 1993 38b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * The Regents of the University of California. All rights reserved. 48b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * 58b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * Redistribution and use in source and binary forms, with or without 68b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * modification, are permitted provided that the following conditions 78b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * are met: 88b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * 1. Redistributions of source code must retain the above copyright 98b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * notice, this list of conditions and the following disclaimer. 108b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * 2. Redistributions in binary form must reproduce the above copyright 118b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * notice, this list of conditions and the following disclaimer in the 128b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * documentation and/or other materials provided with the distribution. 135d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turner * 3. Neither the name of the University nor the names of its contributors 148b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * may be used to endorse or promote products derived from this software 158b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * without specific prior written permission. 168b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * 178b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 188b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 198b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 208b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 218b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 228b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 238b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 248b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 258b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 268b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 278b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * SUCH DAMAGE. 288b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * 298b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * @(#)tcp_timer.c 8.1 (Berkeley) 6/10/93 308b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * tcp_timer.c,v 1.2 1994/08/02 07:49:10 davidg Exp 318b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project */ 328b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project 338b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project#include <slirp.h> 348b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project 355d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turner#ifdef LOG_ENABLED 368b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Projectstruct tcpstat tcpstat; /* tcp statistics */ 375d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turner#endif 385d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turner 398b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Projectu_int32_t tcp_now; /* for RFC 1323 timestamps */ 408b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project 415d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turnerstatic struct tcpcb *tcp_timers(register struct tcpcb *tp, int timer); 425d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turner 438b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project/* 448b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * Fast timeout routine for processing delayed acks 458b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project */ 468b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Projectvoid 475d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turnertcp_fasttimo(void) 488b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project{ 498b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project register struct socket *so; 508b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project register struct tcpcb *tp; 518b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project 528b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project DEBUG_CALL("tcp_fasttimo"); 535d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turner 548b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project so = tcb.so_next; 558b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project if (so) 568b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project for (; so != &tcb; so = so->so_next) 578b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project if ((tp = (struct tcpcb *)so->so_tcpcb) && 588b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project (tp->t_flags & TF_DELACK)) { 598b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project tp->t_flags &= ~TF_DELACK; 608b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project tp->t_flags |= TF_ACKNOW; 615d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turner STAT(tcpstat.tcps_delack++); 628b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project (void) tcp_output(tp); 638b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project } 648b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project} 658b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project 668b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project/* 678b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * Tcp protocol timeout routine called every 500 ms. 688b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * Updates the timers in all active tcb's and 698b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * causes finite state machine actions if timers expire. 708b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project */ 718b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Projectvoid 725d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turnertcp_slowtimo(void) 738b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project{ 748b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project register struct socket *ip, *ipnxt; 758b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project register struct tcpcb *tp; 768b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project register int i; 778b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project 788b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project DEBUG_CALL("tcp_slowtimo"); 795d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turner 808b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project /* 818b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * Search through tcb's and update active timers. 828b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project */ 838b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project ip = tcb.so_next; 848b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project if (ip == 0) 858b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project return; 868b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project for (; ip != &tcb; ip = ipnxt) { 878b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project ipnxt = ip->so_next; 888b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project tp = sototcpcb(ip); 898b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project if (tp == 0) 908b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project continue; 918b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project for (i = 0; i < TCPT_NTIMERS; i++) { 928b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project if (tp->t_timer[i] && --tp->t_timer[i] == 0) { 938b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project tcp_timers(tp,i); 948b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project if (ipnxt->so_prev != ip) 958b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project goto tpgone; 968b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project } 978b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project } 988b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project tp->t_idle++; 998b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project if (tp->t_rtt) 1008b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project tp->t_rtt++; 1018b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Projecttpgone: 1028b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project ; 1038b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project } 1048b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project tcp_iss += TCP_ISSINCR/PR_SLOWHZ; /* increment iss */ 1058b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project#ifdef TCP_COMPAT_42 1068b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project if ((int)tcp_iss < 0) 1078b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project tcp_iss = 0; /* XXX */ 1088b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project#endif 1098b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project tcp_now++; /* for timestamps */ 1108b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project} 1118b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project 1128b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project/* 1138b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * Cancel all timers for TCP tp. 1148b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project */ 1158b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Projectvoid 1165d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turnertcp_canceltimers(struct tcpcb *tp) 1178b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project{ 1188b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project register int i; 1198b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project 1208b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project for (i = 0; i < TCPT_NTIMERS; i++) 1218b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project tp->t_timer[i] = 0; 1228b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project} 1238b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project 1245d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turnerconst int tcp_backoff[TCP_MAXRXTSHIFT + 1] = 1258b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project { 1, 2, 4, 8, 16, 32, 64, 64, 64, 64, 64, 64, 64 }; 1268b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project 1278b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project/* 1288b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * TCP timer processing. 1298b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project */ 1305d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turnerstatic struct tcpcb * 1315d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turnertcp_timers(register struct tcpcb *tp, int timer) 1328b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project{ 1338b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project register int rexmt; 1345d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turner 1358b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project DEBUG_CALL("tcp_timers"); 1365d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turner 1378b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project switch (timer) { 1388b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project 1398b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project /* 1408b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * 2 MSL timeout in shutdown went off. If we're closed but 1418b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * still waiting for peer to close and connection has been idle 1428b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * too long, or if 2MSL time is up from TIME_WAIT, delete connection 1438b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * control block. Otherwise, check again in a bit. 1448b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project */ 1458b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project case TCPT_2MSL: 1468b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project if (tp->t_state != TCPS_TIME_WAIT && 1475d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turner tp->t_idle <= TCP_MAXIDLE) 1485d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turner tp->t_timer[TCPT_2MSL] = TCPTV_KEEPINTVL; 1498b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project else 1508b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project tp = tcp_close(tp); 1518b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project break; 1528b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project 1538b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project /* 1548b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * Retransmission timer went off. Message has not 1558b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * been acked within retransmit interval. Back off 1568b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * to a longer retransmit interval and retransmit one segment. 1578b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project */ 1588b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project case TCPT_REXMT: 1595d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turner 1608b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project /* 1618b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * XXXXX If a packet has timed out, then remove all the queued 1628b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * packets for that session. 1638b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project */ 1645d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turner 1658b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) { 1668b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project /* 1678b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * This is a hack to suit our terminal server here at the uni of canberra 1688b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * since they have trouble with zeroes... It usually lets them through 1698b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * unharmed, but under some conditions, it'll eat the zeros. If we 1708b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * keep retransmitting it, it'll keep eating the zeroes, so we keep 1718b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * retransmitting, and eventually the connection dies... 1728b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * (this only happens on incoming data) 1735d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turner * 1748b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * So, if we were gonna drop the connection from too many retransmits, 1758b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * don't... instead halve the t_maxseg, which might break up the NULLs and 1768b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * let them through 1775d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turner * 1788b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * *sigh* 1798b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project */ 1805d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turner 1818b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project tp->t_maxseg >>= 1; 1828b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project if (tp->t_maxseg < 32) { 1838b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project /* 1848b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * We tried our best, now the connection must die! 1858b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project */ 1868b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project tp->t_rxtshift = TCP_MAXRXTSHIFT; 1875d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turner STAT(tcpstat.tcps_timeoutdrop++); 1888b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project tp = tcp_drop(tp, tp->t_softerror); 1898b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project /* tp->t_softerror : ETIMEDOUT); */ /* XXX */ 1908b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project return (tp); /* XXX */ 1918b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project } 1925d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turner 1938b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project /* 1948b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * Set rxtshift to 6, which is still at the maximum 1958b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * backoff time 1968b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project */ 1978b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project tp->t_rxtshift = 6; 1988b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project } 1995d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turner STAT(tcpstat.tcps_rexmttimeo++); 2008b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift]; 2018b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project TCPT_RANGESET(tp->t_rxtcur, rexmt, 2028b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project (short)tp->t_rttmin, TCPTV_REXMTMAX); /* XXX */ 2038b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project tp->t_timer[TCPT_REXMT] = tp->t_rxtcur; 2048b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project /* 2058b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * If losing, let the lower level know and try for 2068b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * a better route. Also, if we backed off this far, 2078b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * our srtt estimate is probably bogus. Clobber it 2088b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * so we'll take the next rtt measurement as our srtt; 2098b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * move the current srtt into rttvar to keep the current 2108b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * retransmit times until then. 2118b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project */ 2128b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) { 2138b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project/* in_losing(tp->t_inpcb); */ 2148b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT); 2158b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project tp->t_srtt = 0; 2168b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project } 2178b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project tp->snd_nxt = tp->snd_una; 2188b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project /* 2198b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * If timing a segment in this window, stop the timer. 2208b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project */ 2218b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project tp->t_rtt = 0; 2228b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project /* 2238b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * Close the congestion window down to one segment 2248b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * (we'll open it by one segment for each ack we get). 2258b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * Since we probably have a window's worth of unacked 2268b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * data accumulated, this "slow start" keeps us from 2278b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * dumping all that data as back-to-back packets (which 2288b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * might overwhelm an intermediate gateway). 2298b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * 2308b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * There are two phases to the opening: Initially we 2318b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * open by one mss on each ack. This makes the window 2328b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * size increase exponentially with time. If the 2338b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * window is larger than the path can handle, this 2348b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * exponential growth results in dropped packet(s) 2355d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turner * almost immediately. To get more time between 2368b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * drops but still "push" the network to take advantage 2378b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * of improving conditions, we switch from exponential 2388b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * to linear window opening at some threshold size. 2398b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * For a threshold, we use half the current window 2408b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * size, truncated to a multiple of the mss. 2418b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * 2428b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * (the minimum cwnd that will give us exponential 2438b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * growth is 2 mss. We don't allow the threshold 2448b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * to go below this.) 2458b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project */ 2468b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project { 2478b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project u_int win = min(tp->snd_wnd, tp->snd_cwnd) / 2 / tp->t_maxseg; 2488b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project if (win < 2) 2498b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project win = 2; 2508b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project tp->snd_cwnd = tp->t_maxseg; 2518b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project tp->snd_ssthresh = win * tp->t_maxseg; 2528b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project tp->t_dupacks = 0; 2538b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project } 2548b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project (void) tcp_output(tp); 2558b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project break; 2568b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project 2578b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project /* 2588b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * Persistence timer into zero window. 2598b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * Force a byte to be output, if possible. 2608b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project */ 2618b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project case TCPT_PERSIST: 2625d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turner STAT(tcpstat.tcps_persisttimeo++); 2638b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project tcp_setpersist(tp); 2648b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project tp->t_force = 1; 2658b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project (void) tcp_output(tp); 2668b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project tp->t_force = 0; 2678b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project break; 2688b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project 2698b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project /* 2708b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * Keep-alive timer went off; send something 2718b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * or drop connection if idle for too long. 2728b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project */ 2738b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project case TCPT_KEEP: 2745d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turner STAT(tcpstat.tcps_keeptimeo++); 2758b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project if (tp->t_state < TCPS_ESTABLISHED) 2768b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project goto dropit; 2778b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project 2788b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project/* if (tp->t_socket->so_options & SO_KEEPALIVE && */ 2795d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turner if ((SO_OPTIONS) && tp->t_state <= TCPS_CLOSE_WAIT) { 2805d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turner if (tp->t_idle >= TCPTV_KEEP_IDLE + TCP_MAXIDLE) 2818b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project goto dropit; 2828b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project /* 2838b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * Send a packet designed to force a response 2848b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * if the peer is up and reachable: 2858b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * either an ACK if the connection is still alive, 2868b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * or an RST if the peer has closed the connection 2878b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * due to timeout or reboot. 2888b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * Using sequence number tp->snd_una-1 2898b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * causes the transmitted zero-length segment 2908b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * to lie outside the receive window; 2918b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * by the protocol spec, this requires the 2928b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * correspondent TCP to respond. 2938b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project */ 2945d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turner STAT(tcpstat.tcps_keepprobe++); 2958b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project#ifdef TCP_COMPAT_42 2968b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project /* 2978b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * The keepalive packet must have nonzero length 2988b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project * to get a 4.2 host to respond. 2998b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project */ 3005d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turner tcp_respond(tp, &tp->t_template, (struct mbuf *)NULL, 3018b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project tp->rcv_nxt - 1, tp->snd_una - 1, 0); 3028b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project#else 3035d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turner tcp_respond(tp, &tp->t_template, (struct mbuf *)NULL, 3048b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project tp->rcv_nxt, tp->snd_una - 1, 0); 3058b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project#endif 3065d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turner tp->t_timer[TCPT_KEEP] = TCPTV_KEEPINTVL; 3078b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project } else 3085d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turner tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_IDLE; 3098b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project break; 3108b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project 3118b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project dropit: 3125d8f37ad78fc66901af50c762029a501561f3b23David 'Digit' Turner STAT(tcpstat.tcps_keepdrops++); 3138b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project tp = tcp_drop(tp, 0); /* ETIMEDOUT); */ 3148b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project break; 3158b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project } 3168b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project 3178b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project return (tp); 3188b23a6c7e1aee255004dd19098d4c2462b61b849The Android Open Source Project} 319