1 /* tcp_timer.c 4.20 82/04/04 */ 2 3 #include "../h/param.h" 4 #include "../h/systm.h" 5 #include "../h/mbuf.h" 6 #include "../h/socket.h" 7 #include "../h/socketvar.h" 8 #include "../h/protosw.h" 9 #include "../net/in.h" 10 #include "../net/route.h" 11 #include "../net/in_pcb.h" 12 #include "../net/in_systm.h" 13 #include "../net/if.h" 14 #include "../net/ip.h" 15 #include "../net/ip_var.h" 16 #include "../net/tcp.h" 17 #include "../net/tcp_fsm.h" 18 #include "../net/tcp_seq.h" 19 #include "../net/tcp_timer.h" 20 #include "../net/tcp_var.h" 21 #include "../net/tcpip.h" 22 #include "../errno.h" 23 24 int tcpnodelack = 0; 25 /* 26 * Fast timeout routine for processing delayed acks 27 */ 28 tcp_fasttimo() 29 { 30 register struct inpcb *inp; 31 register struct tcpcb *tp; 32 int s = splnet(); 33 COUNT(TCP_FASTTIMO); 34 35 inp = tcb.inp_next; 36 if (inp) 37 for (; inp != &tcb; inp = inp->inp_next) 38 if ((tp = (struct tcpcb *)inp->inp_ppcb) && 39 (tp->t_flags & TF_DELACK)) { 40 tp->t_flags &= ~TF_DELACK; 41 tp->t_flags |= TF_ACKNOW; 42 (void) tcp_output(tp); 43 } 44 splx(s); 45 } 46 47 /* 48 * Tcp protocol timeout routine called every 500 ms. 49 * Updates the timers in all active tcb's and 50 * causes finite state machine actions if timers expire. 51 */ 52 tcp_slowtimo() 53 { 54 register struct inpcb *ip, *ipnxt; 55 register struct tcpcb *tp; 56 int s = splnet(); 57 register int i; 58 COUNT(TCP_SLOWTIMO); 59 60 /* 61 * Search through tcb's and update active timers. 62 */ 63 ip = tcb.inp_next; 64 if (ip == 0) { 65 splx(s); 66 return; 67 } 68 while (ip != &tcb) { 69 tp = intotcpcb(ip); 70 if (tp == 0) 71 continue; 72 ipnxt = ip->inp_next; 73 for (i = 0; i < TCPT_NTIMERS; i++) { 74 if (tp->t_timer[i] && --tp->t_timer[i] == 0) { 75 (void) tcp_usrreq(tp->t_inpcb->inp_socket, 76 PRU_SLOWTIMO, (struct mbuf *)0, 77 (caddr_t)i); 78 if (ipnxt->inp_prev != ip) 79 goto tpgone; 80 } 81 } 82 tp->t_idle++; 83 if (tp->t_rtt) 84 tp->t_rtt++; 85 tpgone: 86 ip = ipnxt; 87 } 88 tcp_iss += TCP_ISSINCR/PR_SLOWHZ; /* increment iss */ 89 splx(s); 90 } 91 92 /* 93 * Cancel all timers for TCP tp. 94 */ 95 tcp_canceltimers(tp) 96 struct tcpcb *tp; 97 { 98 register int i; 99 100 COUNT(TCP_CANCELTIMERS); 101 for (i = 0; i < TCPT_NTIMERS; i++) 102 tp->t_timer[i] = 0; 103 } 104 105 float tcp_backoff[TCP_MAXRXTSHIFT] = 106 { 1.0, 1.2, 1.4, 1.7, 2.0, 3.0, 5.0, 8.0, 16.0, 32.0 }; 107 int tcprexmtprint = 0; 108 int tcpexprexmtbackoff = 0; 109 /* 110 * TCP timer processing. 111 */ 112 tcp_timers(tp, timer) 113 register struct tcpcb *tp; 114 int timer; 115 { 116 117 COUNT(TCP_TIMERS); 118 switch (timer) { 119 120 /* 121 * 2 MSL timeout in shutdown went off. Delete connection 122 * control block. 123 */ 124 case TCPT_2MSL: 125 tcp_close(tp); 126 return; 127 128 /* 129 * Retransmission timer went off. Message has not 130 * been acked within retransmit interval. Back off 131 * to a longer retransmit interval and retransmit all 132 * unacknowledged messages in the window. 133 */ 134 case TCPT_REXMT: 135 tp->t_rxtshift++; 136 if (tp->t_rxtshift > TCP_MAXRXTSHIFT) { 137 tcp_drop(tp, ETIMEDOUT); 138 return; 139 } 140 TCPT_RANGESET(tp->t_timer[TCPT_REXMT], 141 (int)tp->t_srtt, TCPTV_MIN, TCPTV_MAX); 142 if (tcpexprexmtbackoff) { 143 TCPT_RANGESET(tp->t_timer[TCPT_REXMT], 144 tp->t_timer[TCPT_REXMT] << tp->t_rxtshift, 145 TCPTV_MIN, TCPTV_MAX); 146 } else { 147 TCPT_RANGESET(tp->t_timer[TCPT_REXMT], 148 tp->t_timer[TCPT_REXMT] * 149 tcp_backoff[tp->t_rxtshift - 1], 150 TCPTV_MIN, TCPTV_MAX); 151 } 152 if (tcprexmtprint) 153 printf("rexmt set to %d\n", tp->t_timer[TCPT_REXMT]); 154 tp->snd_nxt = tp->snd_una; 155 /* this only transmits one segment! */ 156 (void) tcp_output(tp); 157 return; 158 159 /* 160 * Persistance timer into zero window. 161 * Force a byte to be output, if possible. 162 */ 163 case TCPT_PERSIST: 164 tp->t_force = 1; 165 (void) tcp_output(tp); 166 tp->t_force = 0; 167 TCPT_RANGESET(tp->t_timer[TCPT_PERSIST], 168 tcp_beta * tp->t_srtt, TCPTV_PERSMIN, TCPTV_MAX); 169 return; 170 171 /* 172 * Keep-alive timer went off; send something 173 * or drop connection if idle for too long. 174 */ 175 case TCPT_KEEP: 176 if (tp->t_state < TCPS_ESTABLISHED) 177 goto dropit; 178 if (tp->t_inpcb->inp_socket->so_options & SO_KEEPALIVE) { 179 if (tp->t_idle >= TCPTV_MAXIDLE) 180 goto dropit; 181 /* 182 * Saying tp->rcv_nxt-1 lies about what 183 * we have received, and by the protocol spec 184 * requires the correspondent TCP to respond. 185 * Saying tp->snd_una-1 causes the transmitted 186 * byte to lie outside the receive window; this 187 * is important because we don't necessarily 188 * have a byte in the window to send (consider 189 * a one-way stream!) 190 */ 191 tcp_respond(tp, 192 tp->t_template, tp->rcv_nxt-1, tp->snd_una-1, 0); 193 } else 194 tp->t_idle = 0; 195 tp->t_timer[TCPT_KEEP] = TCPTV_KEEP; 196 return; 197 dropit: 198 tcp_drop(tp, ETIMEDOUT); 199 return; 200 201 #ifdef TCPTRUEOOB 202 /* 203 * Out-of-band data retransmit timer. 204 */ 205 case TCPT_OOBREXMT: 206 if (tp->t_flags & TF_NOOPT) 207 return; 208 (void) tcp_output(tp); 209 TCPT_RANGESET(tp->t_timer[TCPT_OOBREXMT], 210 2 * tp->t_srtt, TCPTV_MIN, TCPTV_MAX); 211 return; 212 #endif 213 } 214 } 215