1 /* tcp_timer.c 4.24 82/06/26 */ 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 34 inp = tcb.inp_next; 35 if (inp) 36 for (; inp != &tcb; inp = inp->inp_next) 37 if ((tp = (struct tcpcb *)inp->inp_ppcb) && 38 (tp->t_flags & TF_DELACK)) { 39 tp->t_flags &= ~TF_DELACK; 40 tp->t_flags |= TF_ACKNOW; 41 (void) tcp_output(tp); 42 } 43 splx(s); 44 } 45 46 /* 47 * Tcp protocol timeout routine called every 500 ms. 48 * Updates the timers in all active tcb's and 49 * causes finite state machine actions if timers expire. 50 */ 51 tcp_slowtimo() 52 { 53 register struct inpcb *ip, *ipnxt; 54 register struct tcpcb *tp; 55 int s = splnet(); 56 register int i; 57 58 /* 59 * Search through tcb's and update active timers. 60 */ 61 ip = tcb.inp_next; 62 if (ip == 0) { 63 splx(s); 64 return; 65 } 66 while (ip != &tcb) { 67 tp = intotcpcb(ip); 68 if (tp == 0) 69 continue; 70 ipnxt = ip->inp_next; 71 for (i = 0; i < TCPT_NTIMERS; i++) { 72 if (tp->t_timer[i] && --tp->t_timer[i] == 0) { 73 (void) tcp_usrreq(tp->t_inpcb->inp_socket, 74 PRU_SLOWTIMO, (struct mbuf *)0, 75 (caddr_t)i); 76 if (ipnxt->inp_prev != ip) 77 goto tpgone; 78 } 79 } 80 tp->t_idle++; 81 if (tp->t_rtt) 82 tp->t_rtt++; 83 tpgone: 84 ip = ipnxt; 85 } 86 tcp_iss += TCP_ISSINCR/PR_SLOWHZ; /* increment iss */ 87 splx(s); 88 } 89 90 /* 91 * Cancel all timers for TCP tp. 92 */ 93 tcp_canceltimers(tp) 94 struct tcpcb *tp; 95 { 96 register int i; 97 98 for (i = 0; i < TCPT_NTIMERS; i++) 99 tp->t_timer[i] = 0; 100 } 101 102 float tcp_backoff[TCP_MAXRXTSHIFT] = 103 { 1.0, 1.2, 1.4, 1.7, 2.0, 3.0, 5.0, 8.0, 16.0, 32.0 }; 104 int tcprexmtprint = 0; 105 int tcpexprexmtbackoff = 0; 106 /* 107 * TCP timer processing. 108 */ 109 tcp_timers(tp, timer) 110 register struct tcpcb *tp; 111 int timer; 112 { 113 114 switch (timer) { 115 116 /* 117 * 2 MSL timeout in shutdown went off. Delete connection 118 * control block. 119 */ 120 case TCPT_2MSL: 121 tcp_close(tp); 122 return; 123 124 /* 125 * Retransmission timer went off. Message has not 126 * been acked within retransmit interval. Back off 127 * to a longer retransmit interval and retransmit all 128 * unacknowledged messages in the window. 129 */ 130 case TCPT_REXMT: 131 tp->t_rxtshift++; 132 if (tp->t_rxtshift > TCP_MAXRXTSHIFT) { 133 tcp_drop(tp, ETIMEDOUT); 134 return; 135 } 136 TCPT_RANGESET(tp->t_timer[TCPT_REXMT], 137 (int)tp->t_srtt, TCPTV_MIN, TCPTV_MAX); 138 if (tcpexprexmtbackoff) { 139 TCPT_RANGESET(tp->t_timer[TCPT_REXMT], 140 tp->t_timer[TCPT_REXMT] << tp->t_rxtshift, 141 TCPTV_MIN, TCPTV_MAX); 142 } else { 143 TCPT_RANGESET(tp->t_timer[TCPT_REXMT], 144 tp->t_timer[TCPT_REXMT] * 145 tcp_backoff[tp->t_rxtshift - 1], 146 TCPTV_MIN, TCPTV_MAX); 147 } 148 if (tcprexmtprint) 149 printf("rexmt set to %d\n", tp->t_timer[TCPT_REXMT]); 150 tp->snd_nxt = tp->snd_una; 151 /* this only transmits one segment! */ 152 (void) tcp_output(tp); 153 return; 154 155 /* 156 * Persistance timer into zero window. 157 * Force a byte to be output, if possible. 158 */ 159 case TCPT_PERSIST: 160 tcp_setpersist(tp); 161 tp->t_force = 1; 162 (void) tcp_output(tp); 163 tp->t_force = 0; 164 return; 165 166 /* 167 * Keep-alive timer went off; send something 168 * or drop connection if idle for too long. 169 */ 170 case TCPT_KEEP: 171 if (tp->t_state < TCPS_ESTABLISHED) 172 goto dropit; 173 if (tp->t_inpcb->inp_socket->so_options & SO_KEEPALIVE) { 174 if (tp->t_idle >= TCPTV_MAXIDLE) 175 goto dropit; 176 /* 177 * Saying tp->rcv_nxt-1 lies about what 178 * we have received, and by the protocol spec 179 * requires the correspondent TCP to respond. 180 * Saying tp->snd_una-1 causes the transmitted 181 * byte to lie outside the receive window; this 182 * is important because we don't necessarily 183 * have a byte in the window to send (consider 184 * a one-way stream!) 185 */ 186 tcp_respond(tp, 187 tp->t_template, tp->rcv_nxt-1, tp->snd_una-1, 0); 188 } else 189 tp->t_idle = 0; 190 tp->t_timer[TCPT_KEEP] = TCPTV_KEEP; 191 return; 192 dropit: 193 tcp_drop(tp, ETIMEDOUT); 194 return; 195 196 #ifdef TCPTRUEOOB 197 /* 198 * Out-of-band data retransmit timer. 199 */ 200 case TCPT_OOBREXMT: 201 if (tp->t_flags & TF_NOOPT) 202 return; 203 (void) tcp_output(tp); 204 TCPT_RANGESET(tp->t_timer[TCPT_OOBREXMT], 205 2 * tp->t_srtt, TCPTV_MIN, TCPTV_MAX); 206 return; 207 #endif 208 } 209 } 210