1 /* tcp_timer.c 4.8 81/12/19 */ 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/in_pcb.h" 11 #include "../net/in_systm.h" 12 #include "../net/if.h" 13 #include "../net/ip.h" 14 #include "../net/ip_var.h" 15 #include "../net/tcp.h" 16 #include "../net/tcp_fsm.h" 17 #include "../net/tcp_seq.h" 18 #include "../net/tcp_timer.h" 19 #include "../net/tcp_var.h" 20 #include "../net/tcpip.h" 21 #include "../errno.h" 22 23 /* 24 * Fast timeout routine for processing delayed acks 25 */ 26 tcp_fasttimo() 27 { 28 29 COUNT(TCP_FASTTIMO); 30 } 31 32 /* 33 * Tcp protocol timeout routine called every 500 ms. 34 * Updates the timers in all active tcb's and 35 * causes finite state machine actions if timers expire. 36 */ 37 tcp_slowtimo() 38 { 39 register struct inpcb *ip; 40 register struct tcpcb *tp; 41 int s = splnet(); 42 register int i; 43 COUNT(TCP_SLOWTIMO); 44 45 /* 46 * Search through tcb's and update active timers. 47 */ 48 ip = tcb.inp_next; 49 if (ip == 0) { 50 splx(s); 51 return; 52 } 53 for (; ip != &tcb; ip = ip->inp_next) { 54 tp = intotcpcb(ip); 55 if (tp == 0) 56 continue; 57 for (i = 0; i < TCPT_NTIMERS; i++) { 58 if (tp->t_timer[i] && --tp->t_timer[i] == 0) 59 (void) tcp_usrreq(tp->t_inpcb->inp_socket, 60 PRU_SLOWTIMO, (struct mbuf *)0, 61 (caddr_t)i); 62 } 63 tp->t_idle++; 64 if (tp->t_rtt) 65 tp->t_rtt++; 66 } 67 tcp_iss += TCP_ISSINCR/PR_SLOWHZ; /* increment iss */ 68 splx(s); 69 } 70 71 /* 72 * Cancel all timers for TCP tp. 73 */ 74 tcp_canceltimers(tp) 75 struct tcpcb *tp; 76 { 77 register int i; 78 79 COUNT(TCP_CANCELTIMERS); 80 for (i = 0; i < TCPT_NTIMERS; i++) 81 tp->t_timer[i] = 0; 82 } 83 84 /* 85 * TCP timer processing. 86 */ 87 tcp_timers(tp, timer) 88 register struct tcpcb *tp; 89 int timer; 90 { 91 92 COUNT(TCP_TIMERS); 93 switch (timer) { 94 95 /* 96 * 2 MSL timeout in shutdown went off. Delete connection 97 * control block. 98 */ 99 case TCPT_2MSL: 100 tcp_close(tp); 101 return; 102 103 /* 104 * Retransmission timer went off. Message has not 105 * been acked within retransmit interval. Back off 106 * to a longer retransmit interval and retransmit all 107 * unacknowledged messages in the window. 108 */ 109 case TCPT_REXMT: 110 tp->t_rxtshift++; 111 TCPT_RANGESET(tp->t_timer[TCPT_REXMT], 112 ((int)(2 * tp->t_srtt)) << tp->t_rxtshift, 113 TCPTV_MIN, TCPTV_MAX); 114 tp->snd_nxt = tp->snd_una; 115 /* this only transmits one segment! */ 116 (void) tcp_output(tp); 117 return; 118 119 /* 120 * Persistance timer into zero window. 121 * Force a byte to be output, if possible. 122 */ 123 case TCPT_PERSIST: 124 tp->t_force = 1; 125 (void) tcp_output(tp); 126 tp->t_force = 0; 127 TCPT_RANGESET(tp->t_timer[TCPT_PERSIST], 128 2 * tp->t_srtt, TCPTV_PERSMIN, TCPTV_MAX); 129 return; 130 131 /* 132 * Keep-alive timer went off; send something 133 * or drop connection if idle for too long. 134 */ 135 case TCPT_KEEP: 136 if (tp->t_state < TCPS_ESTABLISHED || 137 tp->t_idle >= TCPTV_MAXIDLE) { 138 tcp_drop(tp, ETIMEDOUT); 139 return; 140 } 141 tcp_respond(tp->t_template, tp->rcv_nxt, tp->snd_una-1, 0); 142 tp->t_timer[TCPT_KEEP] = TCPTV_KEEP; 143 return; 144 } 145 } 146