1 /* 2 * Copyright (c) 1982, 1986 Regents of the University of California. 3 * All rights reserved. The Berkeley software License Agreement 4 * specifies the terms and conditions for redistribution. 5 * 6 * @(#)tcp_timer.c 7.1 (Berkeley) 06/05/86 7 */ 8 9 #include "param.h" 10 #include "systm.h" 11 #include "mbuf.h" 12 #include "socket.h" 13 #include "socketvar.h" 14 #include "protosw.h" 15 #include "errno.h" 16 17 #include "../net/if.h" 18 #include "../net/route.h" 19 20 #include "in.h" 21 #include "in_pcb.h" 22 #include "in_systm.h" 23 #include "ip.h" 24 #include "ip_var.h" 25 #include "tcp.h" 26 #include "tcp_fsm.h" 27 #include "tcp_seq.h" 28 #include "tcp_timer.h" 29 #include "tcp_var.h" 30 #include "tcpip.h" 31 32 int tcpnodelack = 0; 33 /* 34 * Fast timeout routine for processing delayed acks 35 */ 36 tcp_fasttimo() 37 { 38 register struct inpcb *inp; 39 register struct tcpcb *tp; 40 int s = splnet(); 41 42 inp = tcb.inp_next; 43 if (inp) 44 for (; inp != &tcb; inp = inp->inp_next) 45 if ((tp = (struct tcpcb *)inp->inp_ppcb) && 46 (tp->t_flags & TF_DELACK)) { 47 tp->t_flags &= ~TF_DELACK; 48 tp->t_flags |= TF_ACKNOW; 49 (void) tcp_output(tp); 50 } 51 splx(s); 52 } 53 54 /* 55 * Tcp protocol timeout routine called every 500 ms. 56 * Updates the timers in all active tcb's and 57 * causes finite state machine actions if timers expire. 58 */ 59 tcp_slowtimo() 60 { 61 register struct inpcb *ip, *ipnxt; 62 register struct tcpcb *tp; 63 int s = splnet(); 64 register int i; 65 66 /* 67 * Search through tcb's and update active timers. 68 */ 69 ip = tcb.inp_next; 70 if (ip == 0) { 71 splx(s); 72 return; 73 } 74 for (; ip != &tcb; ip = ipnxt) { 75 ipnxt = ip->inp_next; 76 tp = intotcpcb(ip); 77 if (tp == 0) 78 continue; 79 for (i = 0; i < TCPT_NTIMERS; i++) { 80 if (tp->t_timer[i] && --tp->t_timer[i] == 0) { 81 (void) tcp_usrreq(tp->t_inpcb->inp_socket, 82 PRU_SLOWTIMO, (struct mbuf *)0, 83 (struct mbuf *)i, (struct mbuf *)0); 84 if (ipnxt->inp_prev != ip) 85 goto tpgone; 86 } 87 } 88 tp->t_idle++; 89 if (tp->t_rtt) 90 tp->t_rtt++; 91 tpgone: 92 ; 93 } 94 tcp_iss += TCP_ISSINCR/PR_SLOWHZ; /* increment iss */ 95 #ifdef TCP_COMPAT_42 96 if ((int)tcp_iss < 0) 97 tcp_iss = 0; /* XXX */ 98 #endif 99 splx(s); 100 } 101 102 /* 103 * Cancel all timers for TCP tp. 104 */ 105 tcp_canceltimers(tp) 106 struct tcpcb *tp; 107 { 108 register int i; 109 110 for (i = 0; i < TCPT_NTIMERS; i++) 111 tp->t_timer[i] = 0; 112 } 113 114 int tcp_backoff[TCP_MAXRXTSHIFT+1] = 115 { 1, 2, 4, 6, 8, 10, 15, 20, 30, 30, 30, 30, 30 }; 116 /* 117 * TCP timer processing. 118 */ 119 struct tcpcb * 120 tcp_timers(tp, timer) 121 register struct tcpcb *tp; 122 int timer; 123 { 124 register int rexmt; 125 126 switch (timer) { 127 128 /* 129 * 2 MSL timeout in shutdown went off. If we're closed but 130 * still waiting for peer to close and connection has been idle 131 * too long, or if 2MSL time is up from TIME_WAIT, delete connection 132 * control block. Otherwise, check again in a bit. 133 */ 134 case TCPT_2MSL: 135 if (tp->t_state != TCPS_TIME_WAIT && 136 tp->t_idle <= TCPTV_MAXIDLE) 137 tp->t_timer[TCPT_2MSL] = TCPTV_KEEP; 138 else 139 tp = tcp_close(tp); 140 break; 141 142 /* 143 * Retransmission timer went off. Message has not 144 * been acked within retransmit interval. Back off 145 * to a longer retransmit interval and retransmit one segment. 146 */ 147 case TCPT_REXMT: 148 tp->t_rxtshift++; 149 if (tp->t_rxtshift > TCP_MAXRXTSHIFT) { 150 tp = tcp_drop(tp, ETIMEDOUT); 151 break; 152 } 153 if (tp->t_srtt == 0) 154 rexmt = tcp_beta * TCPTV_SRTTDFLT; 155 else 156 rexmt = (int)(tcp_beta * tp->t_srtt); 157 rexmt *= tcp_backoff[tp->t_rxtshift - 1]; 158 TCPT_RANGESET(tp->t_timer[TCPT_REXMT], rexmt, 159 TCPTV_MIN, TCPTV_MAX); 160 /* 161 * If losing, let the lower level know 162 * and try for a better route. 163 */ 164 if (tp->t_rxtshift >= TCP_MAXRXTSHIFT / 4 || 165 rexmt >= 10 * PR_SLOWHZ) 166 in_losing(tp->t_inpcb); 167 tp->snd_nxt = tp->snd_una; 168 /* 169 * If timing a segment in this window, 170 * and we have already gotten some timing estimate, 171 * stop the timer. 172 */ 173 if (tp->t_rtt && tp->t_srtt) 174 tp->t_rtt = 0; 175 (void) tcp_output(tp); 176 break; 177 178 /* 179 * Persistance timer into zero window. 180 * Force a byte to be output, if possible. 181 */ 182 case TCPT_PERSIST: 183 tcp_setpersist(tp); 184 tp->t_force = 1; 185 (void) tcp_output(tp); 186 tp->t_force = 0; 187 break; 188 189 /* 190 * Keep-alive timer went off; send something 191 * or drop connection if idle for too long. 192 */ 193 case TCPT_KEEP: 194 if (tp->t_state < TCPS_ESTABLISHED) 195 goto dropit; 196 if (tp->t_inpcb->inp_socket->so_options & SO_KEEPALIVE && 197 tp->t_state <= TCPS_CLOSE_WAIT) { 198 if (tp->t_idle >= TCPTV_MAXIDLE) 199 goto dropit; 200 /* 201 * Saying tp->rcv_nxt-1 lies about what 202 * we have received, and by the protocol spec 203 * requires the correspondent TCP to respond. 204 * Saying tp->snd_una-1 causes the transmitted 205 * byte to lie outside the receive window; this 206 * is important because we don't necessarily 207 * have a byte in the window to send (consider 208 * a one-way stream!) 209 */ 210 tcp_respond(tp, 211 tp->t_template, tp->rcv_nxt-1, tp->snd_una-1, 0); 212 } 213 tp->t_timer[TCPT_KEEP] = TCPTV_KEEP; 214 break; 215 dropit: 216 tp = tcp_drop(tp, ETIMEDOUT); 217 break; 218 } 219 return (tp); 220 } 221