| 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 | } |