1 /* tcp_timer.c 4.27 82/10/17 */ 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 "../netinet/in.h" 10 #include "../net/route.h" 11 #include "../netinet/in_pcb.h" 12 #include "../netinet/in_systm.h" 13 #include "../net/if.h" 14 #include "../netinet/ip.h" 15 #include "../netinet/ip_var.h" 16 #include "../netinet/tcp.h" 17 #include "../netinet/tcp_fsm.h" 18 #include "../netinet/tcp_seq.h" 19 #include "../netinet/tcp_timer.h" 20 #include "../netinet/tcp_var.h" 21 #include "../netinet/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 (struct mbuf *)i, 76 (struct sockopt *)0); 77 if (ipnxt->inp_prev != ip) 78 goto tpgone; 79 } 80 } 81 tp->t_idle++; 82 if (tp->t_rtt) 83 tp->t_rtt++; 84 tpgone: 85 ip = ipnxt; 86 } 87 tcp_iss += TCP_ISSINCR/PR_SLOWHZ; /* increment iss */ 88 splx(s); 89 } 90 91 /* 92 * Cancel all timers for TCP tp. 93 */ 94 tcp_canceltimers(tp) 95 struct tcpcb *tp; 96 { 97 register int i; 98 99 for (i = 0; i < TCPT_NTIMERS; i++) 100 tp->t_timer[i] = 0; 101 } 102 103 float tcp_backoff[TCP_MAXRXTSHIFT] = 104 { 1.0, 1.2, 1.4, 1.7, 2.0, 3.0, 5.0, 8.0, 16.0, 32.0 }; 105 int tcprexmtprint = 0; 106 int tcpexprexmtbackoff = 0; 107 /* 108 * TCP timer processing. 109 */ 110 tcp_timers(tp, timer) 111 register struct tcpcb *tp; 112 int timer; 113 { 114 115 switch (timer) { 116 117 /* 118 * 2 MSL timeout in shutdown went off. Delete connection 119 * control block. 120 */ 121 case TCPT_2MSL: 122 tcp_close(tp); 123 return; 124 125 /* 126 * Retransmission timer went off. Message has not 127 * been acked within retransmit interval. Back off 128 * to a longer retransmit interval and retransmit all 129 * unacknowledged messages in the window. 130 */ 131 case TCPT_REXMT: 132 tp->t_rxtshift++; 133 if (tp->t_rxtshift > TCP_MAXRXTSHIFT) { 134 tcp_drop(tp, ETIMEDOUT); 135 return; 136 } 137 TCPT_RANGESET(tp->t_timer[TCPT_REXMT], 138 (int)tp->t_srtt, TCPTV_MIN, TCPTV_MAX); 139 if (tcpexprexmtbackoff) { 140 TCPT_RANGESET(tp->t_timer[TCPT_REXMT], 141 tp->t_timer[TCPT_REXMT] << tp->t_rxtshift, 142 TCPTV_MIN, TCPTV_MAX); 143 } else { 144 TCPT_RANGESET(tp->t_timer[TCPT_REXMT], 145 tp->t_timer[TCPT_REXMT] * 146 tcp_backoff[tp->t_rxtshift - 1], 147 TCPTV_MIN, TCPTV_MAX); 148 } 149 if (tcprexmtprint) 150 printf("rexmt set to %d\n", tp->t_timer[TCPT_REXMT]); 151 tp->snd_nxt = tp->snd_una; 152 /* this only transmits one segment! */ 153 (void) tcp_output(tp); 154 return; 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 return; 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 return; 193 dropit: 194 tcp_drop(tp, ETIMEDOUT); 195 return; 196 } 197 } 198