1 /* tcp_timer.c 4.31 83/02/10 */ 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 "../h/errno.h" 10 11 #include "../net/if.h" 12 #include "../net/route.h" 13 14 #include "../netinet/in.h" 15 #include "../netinet/in_pcb.h" 16 #include "../netinet/in_systm.h" 17 #include "../netinet/ip.h" 18 #include "../netinet/ip_var.h" 19 #include "../netinet/tcp.h" 20 #include "../netinet/tcp_fsm.h" 21 #include "../netinet/tcp_seq.h" 22 #include "../netinet/tcp_timer.h" 23 #include "../netinet/tcp_var.h" 24 #include "../netinet/tcpip.h" 25 26 int tcpnodelack = 0; 27 /* 28 * Fast timeout routine for processing delayed acks 29 */ 30 tcp_fasttimo() 31 { 32 register struct inpcb *inp; 33 register struct tcpcb *tp; 34 int s = splnet(); 35 36 inp = tcb.inp_next; 37 if (inp) 38 for (; inp != &tcb; inp = inp->inp_next) 39 if ((tp = (struct tcpcb *)inp->inp_ppcb) && 40 (tp->t_flags & TF_DELACK)) { 41 tp->t_flags &= ~TF_DELACK; 42 tp->t_flags |= TF_ACKNOW; 43 (void) tcp_output(tp); 44 } 45 splx(s); 46 } 47 48 /* 49 * Tcp protocol timeout routine called every 500 ms. 50 * Updates the timers in all active tcb's and 51 * causes finite state machine actions if timers expire. 52 */ 53 tcp_slowtimo() 54 { 55 register struct inpcb *ip, *ipnxt; 56 register struct tcpcb *tp; 57 int s = splnet(); 58 register int i; 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 (struct mbuf *)i, 78 (struct socketopt *)0); 79 if (ipnxt->inp_prev != ip) 80 goto tpgone; 81 } 82 } 83 tp->t_idle++; 84 if (tp->t_rtt) 85 tp->t_rtt++; 86 tpgone: 87 ip = ipnxt; 88 } 89 tcp_iss += TCP_ISSINCR/PR_SLOWHZ; /* increment iss */ 90 splx(s); 91 } 92 93 /* 94 * Cancel all timers for TCP tp. 95 */ 96 tcp_canceltimers(tp) 97 struct tcpcb *tp; 98 { 99 register int i; 100 101 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 tcpexprexmtbackoff = 0; 108 /* 109 * TCP timer processing. 110 */ 111 struct tcpcb * 112 tcp_timers(tp, timer) 113 register struct tcpcb *tp; 114 int timer; 115 { 116 117 switch (timer) { 118 119 /* 120 * 2 MSL timeout in shutdown went off. Delete connection 121 * control block. 122 */ 123 case TCPT_2MSL: 124 tp = tcp_close(tp); 125 break; 126 127 /* 128 * Retransmission timer went off. Message has not 129 * been acked within retransmit interval. Back off 130 * to a longer retransmit interval and retransmit all 131 * unacknowledged messages in the window. 132 */ 133 case TCPT_REXMT: 134 tp->t_rxtshift++; 135 if (tp->t_rxtshift > TCP_MAXRXTSHIFT) { 136 tp = tcp_drop(tp, ETIMEDOUT); 137 break; 138 } 139 TCPT_RANGESET(tp->t_timer[TCPT_REXMT], 140 (int)tp->t_srtt, TCPTV_MIN, TCPTV_MAX); 141 if (tcpexprexmtbackoff) { 142 TCPT_RANGESET(tp->t_timer[TCPT_REXMT], 143 tp->t_timer[TCPT_REXMT] << tp->t_rxtshift, 144 TCPTV_MIN, TCPTV_MAX); 145 } else { 146 TCPT_RANGESET(tp->t_timer[TCPT_REXMT], 147 tp->t_timer[TCPT_REXMT] * 148 tcp_backoff[tp->t_rxtshift - 1], 149 TCPTV_MIN, TCPTV_MAX); 150 } 151 tp->snd_nxt = tp->snd_una; 152 /* this only transmits one segment! */ 153 (void) tcp_output(tp); 154 break; 155 156 /* 157 * Persistance timer into zero window. 158 * Force a byte to be output, if possible. 159 */ 160 case TCPT_PERSIST: 161 tcp_setpersist(tp); 162 tp->t_force = 1; 163 (void) tcp_output(tp); 164 tp->t_force = 0; 165 break; 166 167 /* 168 * Keep-alive timer went off; send something 169 * or drop connection if idle for too long. 170 */ 171 case TCPT_KEEP: 172 if (tp->t_state < TCPS_ESTABLISHED) 173 goto dropit; 174 if (tp->t_inpcb->inp_socket->so_options & SO_KEEPALIVE) { 175 if (tp->t_idle >= TCPTV_MAXIDLE) 176 goto dropit; 177 /* 178 * Saying tp->rcv_nxt-1 lies about what 179 * we have received, and by the protocol spec 180 * requires the correspondent TCP to respond. 181 * Saying tp->snd_una-1 causes the transmitted 182 * byte to lie outside the receive window; this 183 * is important because we don't necessarily 184 * have a byte in the window to send (consider 185 * a one-way stream!) 186 */ 187 tcp_respond(tp, 188 tp->t_template, tp->rcv_nxt-1, tp->snd_una-1, 0); 189 } else 190 tp->t_idle = 0; 191 tp->t_timer[TCPT_KEEP] = TCPTV_KEEP; 192 break; 193 dropit: 194 tp = tcp_drop(tp, ETIMEDOUT); 195 break; 196 } 197 return (tp); 198 } 199