4.3BSD - /usr/src/sys/netinet/tcp_timer.c

   1: /*
   2:  * Copyright (c) 1982, 1986 Regents of the University of California.
   3:  * All rights reserved.  The Berkeley software License Agreement
   4:  * specifies the terms and conditions for redistribution.
   5:  *
   6:  *	@(#)tcp_timer.c	7.1 (Berkeley) 6/5/86
   7:  */
   8: 
   9: #include "param.h"
  10: #include "systm.h"
  11: #include "mbuf.h"
  12: #include "socket.h"
  13: #include "socketvar.h"
  14: #include "protosw.h"
  15: #include "errno.h"
  16: 
  17: #include "../net/if.h"
  18: #include "../net/route.h"
  19: 
  20: #include "in.h"
  21: #include "in_pcb.h"
  22: #include "in_systm.h"
  23: #include "ip.h"
  24: #include "ip_var.h"
  25: #include "tcp.h"
  26: #include "tcp_fsm.h"
  27: #include "tcp_seq.h"
  28: #include "tcp_timer.h"
  29: #include "tcp_var.h"
  30: #include "tcpip.h"
  31: 
  32: int tcpnodelack = 0;
  33: /*
  34:  * Fast timeout routine for processing delayed acks
  35:  */
  36: tcp_fasttimo()
  37: {
  38:     register struct inpcb *inp;
  39:     register struct tcpcb *tp;
  40:     int s = splnet();
  41: 
  42:     inp = tcb.inp_next;
  43:     if (inp)
  44:     for (; inp != &tcb; inp = inp->inp_next)
  45:         if ((tp = (struct tcpcb *)inp->inp_ppcb) &&
  46:             (tp->t_flags & TF_DELACK)) {
  47:             tp->t_flags &= ~TF_DELACK;
  48:             tp->t_flags |= TF_ACKNOW;
  49:             (void) tcp_output(tp);
  50:         }
  51:     splx(s);
  52: }
  53: 
  54: /*
  55:  * Tcp protocol timeout routine called every 500 ms.
  56:  * Updates the timers in all active tcb's and
  57:  * causes finite state machine actions if timers expire.
  58:  */
  59: tcp_slowtimo()
  60: {
  61:     register struct inpcb *ip, *ipnxt;
  62:     register struct tcpcb *tp;
  63:     int s = splnet();
  64:     register int i;
  65: 
  66:     /*
  67: 	 * Search through tcb's and update active timers.
  68: 	 */
  69:     ip = tcb.inp_next;
  70:     if (ip == 0) {
  71:         splx(s);
  72:         return;
  73:     }
  74:     for (; ip != &tcb; ip = ipnxt) {
  75:         ipnxt = ip->inp_next;
  76:         tp = intotcpcb(ip);
  77:         if (tp == 0)
  78:             continue;
  79:         for (i = 0; i < TCPT_NTIMERS; i++) {
  80:             if (tp->t_timer[i] && --tp->t_timer[i] == 0) {
  81:                 (void) tcp_usrreq(tp->t_inpcb->inp_socket,
  82:                     PRU_SLOWTIMO, (struct mbuf *)0,
  83:                     (struct mbuf *)i, (struct mbuf *)0);
  84:                 if (ipnxt->inp_prev != ip)
  85:                     goto tpgone;
  86:             }
  87:         }
  88:         tp->t_idle++;
  89:         if (tp->t_rtt)
  90:             tp->t_rtt++;
  91: tpgone:
  92:         ;
  93:     }
  94:     tcp_iss += TCP_ISSINCR/PR_SLOWHZ;       /* increment iss */
  95: #ifdef TCP_COMPAT_42
  96:     if ((int)tcp_iss < 0)
  97:         tcp_iss = 0;                /* XXX */
  98: #endif
  99:     splx(s);
 100: }
 101: 
 102: /*
 103:  * Cancel all timers for TCP tp.
 104:  */
 105: tcp_canceltimers(tp)
 106:     struct tcpcb *tp;
 107: {
 108:     register int i;
 109: 
 110:     for (i = 0; i < TCPT_NTIMERS; i++)
 111:         tp->t_timer[i] = 0;
 112: }
 113: 
 114: int tcp_backoff[TCP_MAXRXTSHIFT+1] =
 115:     { 1, 2, 4, 6, 8, 10, 15, 20, 30, 30, 30, 30, 30 };
 116: /*
 117:  * TCP timer processing.
 118:  */
 119: struct tcpcb *
 120: tcp_timers(tp, timer)
 121:     register struct tcpcb *tp;
 122:     int timer;
 123: {
 124:     register int rexmt;
 125: 
 126:     switch (timer) {
 127: 
 128:     /*
 129: 	 * 2 MSL timeout in shutdown went off.  If we're closed but
 130: 	 * still waiting for peer to close and connection has been idle
 131: 	 * too long, or if 2MSL time is up from TIME_WAIT, delete connection
 132: 	 * control block.  Otherwise, check again in a bit.
 133: 	 */
 134:     case TCPT_2MSL:
 135:         if (tp->t_state != TCPS_TIME_WAIT &&
 136:             tp->t_idle <= TCPTV_MAXIDLE)
 137:             tp->t_timer[TCPT_2MSL] = TCPTV_KEEP;
 138:         else
 139:             tp = tcp_close(tp);
 140:         break;
 141: 
 142:     /*
 143: 	 * Retransmission timer went off.  Message has not
 144: 	 * been acked within retransmit interval.  Back off
 145: 	 * to a longer retransmit interval and retransmit one segment.
 146: 	 */
 147:     case TCPT_REXMT:
 148:         tp->t_rxtshift++;
 149:         if (tp->t_rxtshift > TCP_MAXRXTSHIFT) {
 150:             tp = tcp_drop(tp, ETIMEDOUT);
 151:             break;
 152:         }
 153:         if (tp->t_srtt == 0)
 154:             rexmt = tcp_beta * TCPTV_SRTTDFLT;
 155:         else
 156:             rexmt = (int)(tcp_beta * tp->t_srtt);
 157:         rexmt *= tcp_backoff[tp->t_rxtshift - 1];
 158:         TCPT_RANGESET(tp->t_timer[TCPT_REXMT], rexmt,
 159:                 TCPTV_MIN, TCPTV_MAX);
 160:         /*
 161: 		 * If losing, let the lower level know
 162: 		 * and try for a better route.
 163: 		 */
 164:         if (tp->t_rxtshift >= TCP_MAXRXTSHIFT / 4 ||
 165:             rexmt >= 10 * PR_SLOWHZ)
 166:             in_losing(tp->t_inpcb);
 167:         tp->snd_nxt = tp->snd_una;
 168:         /*
 169: 		 * If timing a segment in this window,
 170: 		 * and we have already gotten some timing estimate,
 171: 		 * stop the timer.
 172: 		 */
 173:         if (tp->t_rtt && tp->t_srtt)
 174:             tp->t_rtt = 0;
 175:         (void) tcp_output(tp);
 176:         break;
 177: 
 178:     /*
 179: 	 * Persistance timer into zero window.
 180: 	 * Force a byte to be output, if possible.
 181: 	 */
 182:     case TCPT_PERSIST:
 183:         tcp_setpersist(tp);
 184:         tp->t_force = 1;
 185:         (void) tcp_output(tp);
 186:         tp->t_force = 0;
 187:         break;
 188: 
 189:     /*
 190: 	 * Keep-alive timer went off; send something
 191: 	 * or drop connection if idle for too long.
 192: 	 */
 193:     case TCPT_KEEP:
 194:         if (tp->t_state < TCPS_ESTABLISHED)
 195:             goto dropit;
 196:         if (tp->t_inpcb->inp_socket->so_options & SO_KEEPALIVE &&
 197:             tp->t_state <= TCPS_CLOSE_WAIT) {
 198:                 if (tp->t_idle >= TCPTV_MAXIDLE)
 199:                 goto dropit;
 200:             /*
 201: 			 * Saying tp->rcv_nxt-1 lies about what
 202: 			 * we have received, and by the protocol spec
 203: 			 * requires the correspondent TCP to respond.
 204: 			 * Saying tp->snd_una-1 causes the transmitted
 205: 			 * byte to lie outside the receive window; this
 206: 			 * is important because we don't necessarily
 207: 			 * have a byte in the window to send (consider
 208: 			 * a one-way stream!)
 209: 			 */
 210:             tcp_respond(tp,
 211:                 tp->t_template, tp->rcv_nxt-1, tp->snd_una-1, 0);
 212:         }
 213:         tp->t_timer[TCPT_KEEP] = TCPTV_KEEP;
 214:         break;
 215:     dropit:
 216:         tp = tcp_drop(tp, ETIMEDOUT);
 217:         break;
 218:     }
 219:     return (tp);
 220: }

Defined functions

Defined variables