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1.1 root 1: /* tcp_timer.c 6.1 83/07/29 */
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, (struct mbuf *)0);
78: if (ipnxt->inp_prev != ip)
79: goto tpgone;
80: }
81: }
82: tp->t_idle++;
83: if (tp->t_rtt)
84: tp->t_rtt++;
85: tpgone:
86: ip = ipnxt;
87: }
88: tcp_iss += TCP_ISSINCR/PR_SLOWHZ; /* increment iss */
89: splx(s);
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 };
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: switch (timer) {
117:
118: /*
119: * 2 MSL timeout in shutdown went off. Delete connection
120: * control block.
121: */
122: case TCPT_2MSL:
123: tp = tcp_close(tp);
124: break;
125:
126: /*
127: * Retransmission timer went off. Message has not
128: * been acked within retransmit interval. Back off
129: * to a longer retransmit interval and retransmit all
130: * unacknowledged messages in the window.
131: */
132: case TCPT_REXMT:
133: tp->t_rxtshift++;
134: if (tp->t_rxtshift > TCP_MAXRXTSHIFT) {
135: tp = tcp_drop(tp, ETIMEDOUT);
136: break;
137: }
138: TCPT_RANGESET(tp->t_timer[TCPT_REXMT],
139: (int)tp->t_srtt, TCPTV_MIN, TCPTV_MAX);
140: if (tcpexprexmtbackoff) {
141: TCPT_RANGESET(tp->t_timer[TCPT_REXMT],
142: tp->t_timer[TCPT_REXMT] << tp->t_rxtshift,
143: TCPTV_MIN, TCPTV_MAX);
144: } else {
145: TCPT_RANGESET(tp->t_timer[TCPT_REXMT],
146: tp->t_timer[TCPT_REXMT] *
147: tcp_backoff[tp->t_rxtshift - 1],
148: TCPTV_MIN, TCPTV_MAX);
149: }
150: tp->snd_nxt = tp->snd_una;
151: /* this only transmits one segment! */
152: (void) tcp_output(tp);
153: break;
154:
155: /*
156: * Persistance timer into zero window.
157: * Force a byte to be output, if possible.
158: */
159: case TCPT_PERSIST:
160: tcp_setpersist(tp);
161: tp->t_force = 1;
162: (void) tcp_output(tp);
163: tp->t_force = 0;
164: break;
165:
166: /*
167: * Keep-alive timer went off; send something
168: * or drop connection if idle for too long.
169: */
170: case TCPT_KEEP:
171: if (tp->t_state < TCPS_ESTABLISHED)
172: goto dropit;
173: if (tp->t_inpcb->inp_socket->so_options & SO_KEEPALIVE) {
174: if (tp->t_idle >= TCPTV_MAXIDLE)
175: goto dropit;
176: /*
177: * Saying tp->rcv_nxt-1 lies about what
178: * we have received, and by the protocol spec
179: * requires the correspondent TCP to respond.
180: * Saying tp->snd_una-1 causes the transmitted
181: * byte to lie outside the receive window; this
182: * is important because we don't necessarily
183: * have a byte in the window to send (consider
184: * a one-way stream!)
185: */
186: tcp_respond(tp,
187: tp->t_template, tp->rcv_nxt-1, tp->snd_una-1, 0);
188: } else
189: tp->t_idle = 0;
190: tp->t_timer[TCPT_KEEP] = TCPTV_KEEP;
191: break;
192: dropit:
193: tp = tcp_drop(tp, ETIMEDOUT);
194: break;
195: }
196: return (tp);
197: }
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