Commit | Line | Data |
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8ae0e4b4 | 1 | /* |
7d999c60 | 2 | * Copyright (c) 1982, 1986, 1988, 1990 Regents of the University of California. |
2b6b6284 | 3 | * All rights reserved. |
8ae0e4b4 | 4 | * |
1c15e888 C |
5 | * Redistribution is only permitted until one year after the first shipment |
6 | * of 4.4BSD by the Regents. Otherwise, redistribution and use in source and | |
7 | * binary forms are permitted provided that: (1) source distributions retain | |
8 | * this entire copyright notice and comment, and (2) distributions including | |
9 | * binaries display the following acknowledgement: This product includes | |
10 | * software developed by the University of California, Berkeley and its | |
11 | * contributors'' in the documentation or other materials provided with the | |
12 | * distribution and in all advertising materials mentioning features or use | |
13 | * of this software. Neither the name of the University nor the names of | |
14 | * its contributors may be used to endorse or promote products derived from | |
15 | * this software without specific prior written permission. | |
16 | * THIS SOFTWARE IS PROVIDED AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED | |
17 | * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF | |
18 | * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. | |
2b6b6284 | 19 | * |
1c15e888 | 20 | * @(#)tcp_timer.c 7.18 (Berkeley) 6/28/90 |
8ae0e4b4 | 21 | */ |
f03530e6 | 22 | |
20666ad3 JB |
23 | #include "param.h" |
24 | #include "systm.h" | |
cc072043 | 25 | #include "malloc.h" |
20666ad3 JB |
26 | #include "mbuf.h" |
27 | #include "socket.h" | |
28 | #include "socketvar.h" | |
29 | #include "protosw.h" | |
30 | #include "errno.h" | |
6e7edb25 BJ |
31 | |
32 | #include "../net/if.h" | |
c124e997 | 33 | #include "../net/route.h" |
f4d55810 | 34 | |
20666ad3 | 35 | #include "in.h" |
20666ad3 JB |
36 | #include "in_systm.h" |
37 | #include "ip.h" | |
2b25f79c | 38 | #include "in_pcb.h" |
20666ad3 JB |
39 | #include "ip_var.h" |
40 | #include "tcp.h" | |
41 | #include "tcp_fsm.h" | |
42 | #include "tcp_seq.h" | |
43 | #include "tcp_timer.h" | |
44 | #include "tcp_var.h" | |
45 | #include "tcpip.h" | |
f03530e6 | 46 | |
8a36cf82 MK |
47 | int tcp_keepidle = TCPTV_KEEP_IDLE; |
48 | int tcp_keepintvl = TCPTV_KEEPINTVL; | |
49 | int tcp_maxidle; | |
f03530e6 BJ |
50 | /* |
51 | * Fast timeout routine for processing delayed acks | |
52 | */ | |
53 | tcp_fasttimo() | |
54 | { | |
b8b9174f BJ |
55 | register struct inpcb *inp; |
56 | register struct tcpcb *tp; | |
57 | int s = splnet(); | |
b8b9174f | 58 | |
fd5dc5f0 BJ |
59 | inp = tcb.inp_next; |
60 | if (inp) | |
61 | for (; inp != &tcb; inp = inp->inp_next) | |
b8b9174f BJ |
62 | if ((tp = (struct tcpcb *)inp->inp_ppcb) && |
63 | (tp->t_flags & TF_DELACK)) { | |
64 | tp->t_flags &= ~TF_DELACK; | |
65 | tp->t_flags |= TF_ACKNOW; | |
35f3fc10 | 66 | tcpstat.tcps_delack++; |
b8b9174f BJ |
67 | (void) tcp_output(tp); |
68 | } | |
69 | splx(s); | |
f03530e6 BJ |
70 | } |
71 | ||
72 | /* | |
73 | * Tcp protocol timeout routine called every 500 ms. | |
74 | * Updates the timers in all active tcb's and | |
75 | * causes finite state machine actions if timers expire. | |
76 | */ | |
77 | tcp_slowtimo() | |
78 | { | |
1e977657 | 79 | register struct inpcb *ip, *ipnxt; |
f03530e6 BJ |
80 | register struct tcpcb *tp; |
81 | int s = splnet(); | |
f03530e6 | 82 | register int i; |
f03530e6 | 83 | |
8a36cf82 | 84 | tcp_maxidle = TCPTV_KEEPCNT * tcp_keepintvl; |
f03530e6 BJ |
85 | /* |
86 | * Search through tcb's and update active timers. | |
87 | */ | |
4aed14e3 BJ |
88 | ip = tcb.inp_next; |
89 | if (ip == 0) { | |
90 | splx(s); | |
91 | return; | |
92 | } | |
039b88d5 MK |
93 | for (; ip != &tcb; ip = ipnxt) { |
94 | ipnxt = ip->inp_next; | |
f03530e6 | 95 | tp = intotcpcb(ip); |
37de812c BJ |
96 | if (tp == 0) |
97 | continue; | |
a6503abf | 98 | for (i = 0; i < TCPT_NTIMERS; i++) { |
1e977657 | 99 | if (tp->t_timer[i] && --tp->t_timer[i] == 0) { |
f03530e6 BJ |
100 | (void) tcp_usrreq(tp->t_inpcb->inp_socket, |
101 | PRU_SLOWTIMO, (struct mbuf *)0, | |
755d8841 | 102 | (struct mbuf *)i, (struct mbuf *)0); |
1e977657 BJ |
103 | if (ipnxt->inp_prev != ip) |
104 | goto tpgone; | |
105 | } | |
f03530e6 | 106 | } |
405c9168 BJ |
107 | tp->t_idle++; |
108 | if (tp->t_rtt) | |
109 | tp->t_rtt++; | |
1e977657 | 110 | tpgone: |
039b88d5 | 111 | ; |
f03530e6 | 112 | } |
a6503abf | 113 | tcp_iss += TCP_ISSINCR/PR_SLOWHZ; /* increment iss */ |
367bed15 | 114 | #ifdef TCP_COMPAT_42 |
c50542f3 MK |
115 | if ((int)tcp_iss < 0) |
116 | tcp_iss = 0; /* XXX */ | |
117 | #endif | |
f03530e6 BJ |
118 | splx(s); |
119 | } | |
120 | ||
121 | /* | |
a6503abf | 122 | * Cancel all timers for TCP tp. |
f03530e6 | 123 | */ |
0974b45c | 124 | tcp_canceltimers(tp) |
f03530e6 BJ |
125 | struct tcpcb *tp; |
126 | { | |
f03530e6 BJ |
127 | register int i; |
128 | ||
a6503abf BJ |
129 | for (i = 0; i < TCPT_NTIMERS; i++) |
130 | tp->t_timer[i] = 0; | |
f03530e6 BJ |
131 | } |
132 | ||
a6bbda13 MK |
133 | int tcp_backoff[TCP_MAXRXTSHIFT + 1] = |
134 | { 1, 2, 4, 8, 16, 32, 64, 64, 64, 64, 64, 64, 64 }; | |
8b6ad229 | 135 | |
f03530e6 | 136 | /* |
405c9168 | 137 | * TCP timer processing. |
f03530e6 | 138 | */ |
0e3936fa | 139 | struct tcpcb * |
a6503abf | 140 | tcp_timers(tp, timer) |
f03530e6 | 141 | register struct tcpcb *tp; |
a6503abf | 142 | int timer; |
f03530e6 | 143 | { |
2a89e5a6 | 144 | register int rexmt; |
f03530e6 | 145 | |
0974b45c | 146 | switch (timer) { |
f03530e6 | 147 | |
405c9168 | 148 | /* |
6209c5c4 MK |
149 | * 2 MSL timeout in shutdown went off. If we're closed but |
150 | * still waiting for peer to close and connection has been idle | |
151 | * too long, or if 2MSL time is up from TIME_WAIT, delete connection | |
152 | * control block. Otherwise, check again in a bit. | |
405c9168 | 153 | */ |
a6503abf | 154 | case TCPT_2MSL: |
6209c5c4 | 155 | if (tp->t_state != TCPS_TIME_WAIT && |
8a36cf82 MK |
156 | tp->t_idle <= tcp_maxidle) |
157 | tp->t_timer[TCPT_2MSL] = tcp_keepintvl; | |
6209c5c4 MK |
158 | else |
159 | tp = tcp_close(tp); | |
0e3936fa | 160 | break; |
f03530e6 | 161 | |
405c9168 BJ |
162 | /* |
163 | * Retransmission timer went off. Message has not | |
164 | * been acked within retransmit interval. Back off | |
eeaf00e3 | 165 | * to a longer retransmit interval and retransmit one segment. |
405c9168 | 166 | */ |
a6503abf | 167 | case TCPT_REXMT: |
a6bbda13 MK |
168 | if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) { |
169 | tp->t_rxtshift = TCP_MAXRXTSHIFT; | |
35f3fc10 | 170 | tcpstat.tcps_timeoutdrop++; |
7d999c60 MK |
171 | tp = tcp_drop(tp, tp->t_softerror ? |
172 | tp->t_softerror : ETIMEDOUT); | |
0e3936fa | 173 | break; |
fd5dc5f0 | 174 | } |
35f3fc10 | 175 | tcpstat.tcps_rexmttimeo++; |
7d999c60 MK |
176 | rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift]; |
177 | TCPT_RANGESET(tp->t_rxtcur, rexmt, | |
178 | tp->t_rttmin, TCPTV_REXMTMAX); | |
a6bbda13 | 179 | tp->t_timer[TCPT_REXMT] = tp->t_rxtcur; |
6a4fd140 | 180 | /* |
a6bbda13 MK |
181 | * If losing, let the lower level know and try for |
182 | * a better route. Also, if we backed off this far, | |
183 | * our srtt estimate is probably bogus. Clobber it | |
184 | * so we'll take the next rtt measurement as our srtt; | |
185 | * move the current srtt into rttvar to keep the current | |
186 | * retransmit times until then. | |
6a4fd140 | 187 | */ |
a6bbda13 | 188 | if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) { |
6a4fd140 | 189 | in_losing(tp->t_inpcb); |
7d999c60 | 190 | tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT); |
a6bbda13 MK |
191 | tp->t_srtt = 0; |
192 | } | |
405c9168 | 193 | tp->snd_nxt = tp->snd_una; |
7872cc0a | 194 | /* |
7cc62c26 | 195 | * If timing a segment in this window, stop the timer. |
7872cc0a | 196 | */ |
7cc62c26 | 197 | tp->t_rtt = 0; |
2e5a76f2 MK |
198 | /* |
199 | * Close the congestion window down to one segment | |
200 | * (we'll open it by one segment for each ack we get). | |
201 | * Since we probably have a window's worth of unacked | |
202 | * data accumulated, this "slow start" keeps us from | |
203 | * dumping all that data as back-to-back packets (which | |
204 | * might overwhelm an intermediate gateway). | |
6f854ef4 MK |
205 | * |
206 | * There are two phases to the opening: Initially we | |
207 | * open by one mss on each ack. This makes the window | |
208 | * size increase exponentially with time. If the | |
209 | * window is larger than the path can handle, this | |
210 | * exponential growth results in dropped packet(s) | |
211 | * almost immediately. To get more time between | |
212 | * drops but still "push" the network to take advantage | |
213 | * of improving conditions, we switch from exponential | |
214 | * to linear window opening at some threshhold size. | |
215 | * For a threshhold, we use half the current window | |
216 | * size, truncated to a multiple of the mss. | |
217 | * | |
218 | * (the minimum cwnd that will give us exponential | |
219 | * growth is 2 mss. We don't allow the threshhold | |
220 | * to go below this.) | |
2e5a76f2 | 221 | */ |
6f854ef4 | 222 | { |
7d999c60 | 223 | u_int win = min(tp->snd_wnd, tp->snd_cwnd) / 2 / tp->t_maxseg; |
6f854ef4 MK |
224 | if (win < 2) |
225 | win = 2; | |
2e5a76f2 | 226 | tp->snd_cwnd = tp->t_maxseg; |
6f854ef4 | 227 | tp->snd_ssthresh = win * tp->t_maxseg; |
7d999c60 | 228 | tp->t_dupacks = 0; |
6f854ef4 | 229 | } |
405c9168 | 230 | (void) tcp_output(tp); |
0e3936fa | 231 | break; |
f03530e6 | 232 | |
405c9168 BJ |
233 | /* |
234 | * Persistance timer into zero window. | |
235 | * Force a byte to be output, if possible. | |
236 | */ | |
a6503abf | 237 | case TCPT_PERSIST: |
35f3fc10 | 238 | tcpstat.tcps_persisttimeo++; |
a13c006d | 239 | tcp_setpersist(tp); |
405c9168 BJ |
240 | tp->t_force = 1; |
241 | (void) tcp_output(tp); | |
242 | tp->t_force = 0; | |
0e3936fa | 243 | break; |
f03530e6 | 244 | |
405c9168 BJ |
245 | /* |
246 | * Keep-alive timer went off; send something | |
247 | * or drop connection if idle for too long. | |
248 | */ | |
a6503abf | 249 | case TCPT_KEEP: |
35f3fc10 | 250 | tcpstat.tcps_keeptimeo++; |
f3cdd721 BJ |
251 | if (tp->t_state < TCPS_ESTABLISHED) |
252 | goto dropit; | |
c0200c65 MK |
253 | if (tp->t_inpcb->inp_socket->so_options & SO_KEEPALIVE && |
254 | tp->t_state <= TCPS_CLOSE_WAIT) { | |
8a36cf82 | 255 | if (tp->t_idle >= tcp_keepidle + tcp_maxidle) |
f3cdd721 | 256 | goto dropit; |
3bd14c98 | 257 | /* |
35f3fc10 MK |
258 | * Send a packet designed to force a response |
259 | * if the peer is up and reachable: | |
260 | * either an ACK if the connection is still alive, | |
261 | * or an RST if the peer has closed the connection | |
262 | * due to timeout or reboot. | |
263 | * Using sequence number tp->snd_una-1 | |
264 | * causes the transmitted zero-length segment | |
265 | * to lie outside the receive window; | |
266 | * by the protocol spec, this requires the | |
267 | * correspondent TCP to respond. | |
3bd14c98 | 268 | */ |
35f3fc10 | 269 | tcpstat.tcps_keepprobe++; |
eeef4ac3 MK |
270 | #ifdef TCP_COMPAT_42 |
271 | /* | |
272 | * The keepalive packet must have nonzero length | |
273 | * to get a 4.2 host to respond. | |
274 | */ | |
cc072043 | 275 | tcp_respond(tp, tp->t_template, (struct mbuf *)NULL, |
eeef4ac3 MK |
276 | tp->rcv_nxt - 1, tp->snd_una - 1, 0); |
277 | #else | |
cc072043 | 278 | tcp_respond(tp, tp->t_template, (struct mbuf *)NULL, |
eeef4ac3 MK |
279 | tp->rcv_nxt, tp->snd_una - 1, 0); |
280 | #endif | |
8a36cf82 MK |
281 | tp->t_timer[TCPT_KEEP] = tcp_keepintvl; |
282 | } else | |
283 | tp->t_timer[TCPT_KEEP] = tcp_keepidle; | |
0e3936fa | 284 | break; |
f3cdd721 | 285 | dropit: |
35f3fc10 | 286 | tcpstat.tcps_keepdrops++; |
0e3936fa SL |
287 | tp = tcp_drop(tp, ETIMEDOUT); |
288 | break; | |
f03530e6 | 289 | } |
0e3936fa | 290 | return (tp); |
f03530e6 | 291 | } |