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1.1 root 1: /* tcp_timer.c 6.1 83/07/29 */
2: #include "tcp.h"
3: #if NTCP > 0
4:
5: #include "../h/param.h"
6: #include "../h/systm.h"
7: #include "../h/stream.h"
8: #include "../h/inet/mbuf.h"
9: #include "../h/inet/in.h"
10: #include "../h/inet/ip.h"
11: #include "../h/inet/ip_var.h"
12: #include "../h/inet/tcp.h"
13: #include "../h/inet/tcp_fsm.h"
14: #include "../h/inet/tcp_seq.h"
15: #include "../h/inet/tcp_timer.h"
16: #include "../h/inet/tcp_var.h"
17: #include "../h/inet/tcpip.h"
18: #include "../h/inet/socket.h"
19:
20: int tcpnodelack = 0;
21: /*
22: * Fast timeout routine for processing delayed acks
23: */
24: tcp_fasttimo()
25: {
26: register struct socket *so;
27: extern struct socket tcpsocks[];
28: extern Ntcp;
29: register struct tcpcb *tp;
30: int s = spl6();
31: extern tcp_busy;
32:
33: if(tcp_busy)
34: goto busy;
35: tcp_busy++;
36: for(so = tcpsocks; so < &tcpsocks[Ntcp]; so++)
37: if ((tp = so->so_tcpcb) &&
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: --tcp_busy;
44: busy:
45: timeout(tcp_fasttimo, (caddr_t) 0, hz / 5);
46: splx(s);
47: }
48:
49: /*
50: * Tcp protocol timeout routine called every 500 ms.
51: * Updates the timers in all active tcb's and
52: * causes finite state machine actions if timers expire.
53: */
54: tcp_slowtimo()
55: {
56: extern int tcp_busy;
57: register struct socket *so;
58: register struct tcpcb *tp;
59: extern struct socket tcpsocks[];
60: extern Ntcp;
61: int s = spl6();
62: register int i;
63:
64: if(tcp_busy)
65: goto busy;
66: /*
67: * Search through tcb's and update active timers.
68: */
69: tcp_busy++;
70: for(so = tcpsocks; so < &tcpsocks[Ntcp]; so++){
71: if((so->so_state&SS_ACTIVE) == 0)
72: continue;
73: tp = sototcpcb(so);
74: if (tp == 0)
75: continue;
76: for (i = 0; i < TCPT_NTIMERS; i++) {
77: if (tp->t_timer[i] && --tp->t_timer[i] == 0) {
78: tcp_timers(tp, i);
79: }
80: }
81: tp->t_idle++;
82: if (tp->t_rtt)
83: tp->t_rtt++;
84: }
85: --tcp_busy;
86: busy:
87: tcp_iss += TCP_ISSINCR/PR_SLOWHZ;
88: splx(s);
89: timeout(tcp_slowtimo, (caddr_t)0, hz/PR_SLOWHZ);
90: }
91:
92: /*
93: * Cancel all timers for TCP tp.
94: */
95: tcp_canceltimers(tp)
96: struct tcpcb *tp;
97: {
98: register int i;
99:
100: for (i = 0; i < TCPT_NTIMERS; i++)
101: tp->t_timer[i] = 0;
102: }
103:
104: float tcp_backoff[TCP_MAXRXTSHIFT] =
105: { 1.0, 1.2, 1.4, 1.7, 2.0, 3.0, 5.0, 8.0, 16.0, 32.0, 64.0, 128.0 };
106: int tcpexprexmtbackoff = 0;
107: /*
108: * TCP timer processing.
109: */
110: struct tcpcb *
111: tcp_timers(tp, timer)
112: register struct tcpcb *tp;
113: int timer;
114: {
115:
116: if(tp->t_state == TCPS_ESTABLISHED)
117: tcpstat.tcps_timeouts[timer]++;
118: switch (timer) {
119:
120: /*
121: * 2 MSL timeout in shutdown went off. Delete connection
122: * control block.
123: */
124: case TCPT_2MSL:
125: tp = tcp_close(tp);
126: break;
127:
128: /*
129: * Retransmission timer went off. Message has not
130: * been acked within retransmit interval. Back off
131: * to a longer retransmit interval and retransmit all
132: * unacknowledged messages in the window.
133: */
134: case TCPT_REXMT:
135: tp->t_rxtshift++;
136: if (tp->t_rxtshift > TCP_MAXRXTSHIFT) {
137: tp = tcp_drop(tp);
138: break;
139: }
140: TCPT_RANGESET(tp->t_timer[TCPT_REXMT],
141: (int)tp->t_srtt, TCPTV_MIN, TCPTV_MAX);
142: if (tcpexprexmtbackoff) {
143: TCPT_RANGESET(tp->t_timer[TCPT_REXMT],
144: tp->t_timer[TCPT_REXMT] << tp->t_rxtshift,
145: TCPTV_MIN, TCPTV_MAX);
146: } else {
147: TCPT_RANGESET(tp->t_timer[TCPT_REXMT],
148: tp->t_timer[TCPT_REXMT] *
149: tcp_backoff[tp->t_rxtshift - 1],
150: TCPTV_MIN, TCPTV_MAX);
151: }
152: tp->snd_nxt = tp->snd_una;
153: /* this only transmits one segment! */
154: (void) tcp_output(tp);
155: break;
156:
157: /*
158: * Persistance timer into zero window.
159: * Force a byte to be output, if possible.
160: */
161: case TCPT_PERSIST:
162: tcp_setpersist(tp);
163: tp->t_force = 1;
164: (void) tcp_output(tp);
165: tp->t_force = 0;
166: break;
167:
168: /*
169: * Keep-alive timer went off; send something
170: * or drop connection if idle for too long.
171: */
172: case TCPT_KEEP:
173: if (tp->t_state < TCPS_ESTABLISHED)
174: goto dropit;
175: if (tp->t_socket->so_options & SO_KEEPALIVE) {
176: if (tp->t_idle >= TCPTV_MAXIDLE)
177: goto dropit;
178: /*
179: * Saying tp->rcv_nxt-1 lies about what
180: * we have received, and by the protocol spec
181: * requires the correspondent TCP to respond.
182: * Saying tp->snd_una-1 causes the transmitted
183: * byte to lie outside the receive window; this
184: * is important because we don't necessarily
185: * have a byte in the window to send (consider
186: * a one-way stream!)
187: */
188: tcp_respond(tp,
189: tp->t_template, tp->rcv_nxt-1, tp->snd_una-1, 0);
190: } else
191: tp->t_idle = 0;
192: tp->t_timer[TCPT_KEEP] = TCPTV_KEEP;
193: break;
194: dropit:
195: tp = tcp_drop(tp);
196: break;
197: }
198: return (tp);
199: }
200: #endif
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