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8ae0e4b4 | 1 | /* |
e7a3707f KB |
2 | * Copyright (c) 1982, 1986, 1988, 1990, 1993 |
3 | * The Regents of the University of California. All rights reserved. | |
8ae0e4b4 | 4 | * |
dbf0c423 | 5 | * %sccs.include.redist.c% |
2b6b6284 | 6 | * |
e7a3707f | 7 | * @(#)tcp_timer.c 8.1 (Berkeley) %G% |
8ae0e4b4 | 8 | */ |
f03530e6 | 9 | |
55ad7758 | 10 | #ifndef TUBA_INCLUDE |
5548a02f KB |
11 | #include <sys/param.h> |
12 | #include <sys/systm.h> | |
13 | #include <sys/malloc.h> | |
14 | #include <sys/mbuf.h> | |
15 | #include <sys/socket.h> | |
16 | #include <sys/socketvar.h> | |
17 | #include <sys/protosw.h> | |
18 | #include <sys/errno.h> | |
6e7edb25 | 19 | |
5548a02f KB |
20 | #include <net/if.h> |
21 | #include <net/route.h> | |
f4d55810 | 22 | |
5548a02f KB |
23 | #include <netinet/in.h> |
24 | #include <netinet/in_systm.h> | |
25 | #include <netinet/ip.h> | |
26 | #include <netinet/in_pcb.h> | |
27 | #include <netinet/ip_var.h> | |
28 | #include <netinet/tcp.h> | |
29 | #include <netinet/tcp_fsm.h> | |
30 | #include <netinet/tcp_seq.h> | |
31 | #include <netinet/tcp_timer.h> | |
32 | #include <netinet/tcp_var.h> | |
33 | #include <netinet/tcpip.h> | |
f03530e6 | 34 | |
8a36cf82 MK |
35 | int tcp_keepidle = TCPTV_KEEP_IDLE; |
36 | int tcp_keepintvl = TCPTV_KEEPINTVL; | |
37 | int tcp_maxidle; | |
55ad7758 | 38 | #endif /* TUBA_INCLUDE */ |
f03530e6 BJ |
39 | /* |
40 | * Fast timeout routine for processing delayed acks | |
41 | */ | |
c46785cb | 42 | void |
f03530e6 BJ |
43 | tcp_fasttimo() |
44 | { | |
b8b9174f BJ |
45 | register struct inpcb *inp; |
46 | register struct tcpcb *tp; | |
47 | int s = splnet(); | |
b8b9174f | 48 | |
fd5dc5f0 BJ |
49 | inp = tcb.inp_next; |
50 | if (inp) | |
51 | for (; inp != &tcb; inp = inp->inp_next) | |
b8b9174f BJ |
52 | if ((tp = (struct tcpcb *)inp->inp_ppcb) && |
53 | (tp->t_flags & TF_DELACK)) { | |
54 | tp->t_flags &= ~TF_DELACK; | |
55 | tp->t_flags |= TF_ACKNOW; | |
35f3fc10 | 56 | tcpstat.tcps_delack++; |
b8b9174f BJ |
57 | (void) tcp_output(tp); |
58 | } | |
59 | splx(s); | |
f03530e6 BJ |
60 | } |
61 | ||
62 | /* | |
63 | * Tcp protocol timeout routine called every 500 ms. | |
64 | * Updates the timers in all active tcb's and | |
65 | * causes finite state machine actions if timers expire. | |
66 | */ | |
c46785cb | 67 | void |
f03530e6 BJ |
68 | tcp_slowtimo() |
69 | { | |
1e977657 | 70 | register struct inpcb *ip, *ipnxt; |
f03530e6 BJ |
71 | register struct tcpcb *tp; |
72 | int s = splnet(); | |
f03530e6 | 73 | register int i; |
f03530e6 | 74 | |
8a36cf82 | 75 | tcp_maxidle = TCPTV_KEEPCNT * tcp_keepintvl; |
f03530e6 BJ |
76 | /* |
77 | * Search through tcb's and update active timers. | |
78 | */ | |
4aed14e3 BJ |
79 | ip = tcb.inp_next; |
80 | if (ip == 0) { | |
81 | splx(s); | |
82 | return; | |
83 | } | |
039b88d5 MK |
84 | for (; ip != &tcb; ip = ipnxt) { |
85 | ipnxt = ip->inp_next; | |
f03530e6 | 86 | tp = intotcpcb(ip); |
37de812c BJ |
87 | if (tp == 0) |
88 | continue; | |
a6503abf | 89 | for (i = 0; i < TCPT_NTIMERS; i++) { |
1e977657 | 90 | if (tp->t_timer[i] && --tp->t_timer[i] == 0) { |
f03530e6 BJ |
91 | (void) tcp_usrreq(tp->t_inpcb->inp_socket, |
92 | PRU_SLOWTIMO, (struct mbuf *)0, | |
755d8841 | 93 | (struct mbuf *)i, (struct mbuf *)0); |
1e977657 BJ |
94 | if (ipnxt->inp_prev != ip) |
95 | goto tpgone; | |
96 | } | |
f03530e6 | 97 | } |
405c9168 BJ |
98 | tp->t_idle++; |
99 | if (tp->t_rtt) | |
100 | tp->t_rtt++; | |
1e977657 | 101 | tpgone: |
039b88d5 | 102 | ; |
f03530e6 | 103 | } |
a6503abf | 104 | tcp_iss += TCP_ISSINCR/PR_SLOWHZ; /* increment iss */ |
367bed15 | 105 | #ifdef TCP_COMPAT_42 |
c50542f3 MK |
106 | if ((int)tcp_iss < 0) |
107 | tcp_iss = 0; /* XXX */ | |
108 | #endif | |
69d96ae2 | 109 | tcp_now++; /* for timestamps */ |
f03530e6 BJ |
110 | splx(s); |
111 | } | |
55ad7758 | 112 | #ifndef TUBA_INCLUDE |
f03530e6 BJ |
113 | |
114 | /* | |
a6503abf | 115 | * Cancel all timers for TCP tp. |
f03530e6 | 116 | */ |
c46785cb | 117 | void |
0974b45c | 118 | tcp_canceltimers(tp) |
f03530e6 BJ |
119 | struct tcpcb *tp; |
120 | { | |
f03530e6 BJ |
121 | register int i; |
122 | ||
a6503abf BJ |
123 | for (i = 0; i < TCPT_NTIMERS; i++) |
124 | tp->t_timer[i] = 0; | |
f03530e6 BJ |
125 | } |
126 | ||
a6bbda13 MK |
127 | int tcp_backoff[TCP_MAXRXTSHIFT + 1] = |
128 | { 1, 2, 4, 8, 16, 32, 64, 64, 64, 64, 64, 64, 64 }; | |
8b6ad229 | 129 | |
f03530e6 | 130 | /* |
405c9168 | 131 | * TCP timer processing. |
f03530e6 | 132 | */ |
0e3936fa | 133 | struct tcpcb * |
a6503abf | 134 | tcp_timers(tp, timer) |
f03530e6 | 135 | register struct tcpcb *tp; |
a6503abf | 136 | int timer; |
f03530e6 | 137 | { |
2a89e5a6 | 138 | register int rexmt; |
f03530e6 | 139 | |
0974b45c | 140 | switch (timer) { |
f03530e6 | 141 | |
405c9168 | 142 | /* |
6209c5c4 MK |
143 | * 2 MSL timeout in shutdown went off. If we're closed but |
144 | * still waiting for peer to close and connection has been idle | |
145 | * too long, or if 2MSL time is up from TIME_WAIT, delete connection | |
146 | * control block. Otherwise, check again in a bit. | |
405c9168 | 147 | */ |
a6503abf | 148 | case TCPT_2MSL: |
6209c5c4 | 149 | if (tp->t_state != TCPS_TIME_WAIT && |
8a36cf82 MK |
150 | tp->t_idle <= tcp_maxidle) |
151 | tp->t_timer[TCPT_2MSL] = tcp_keepintvl; | |
6209c5c4 MK |
152 | else |
153 | tp = tcp_close(tp); | |
0e3936fa | 154 | break; |
f03530e6 | 155 | |
405c9168 BJ |
156 | /* |
157 | * Retransmission timer went off. Message has not | |
158 | * been acked within retransmit interval. Back off | |
eeaf00e3 | 159 | * to a longer retransmit interval and retransmit one segment. |
405c9168 | 160 | */ |
a6503abf | 161 | case TCPT_REXMT: |
a6bbda13 MK |
162 | if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) { |
163 | tp->t_rxtshift = TCP_MAXRXTSHIFT; | |
35f3fc10 | 164 | tcpstat.tcps_timeoutdrop++; |
7d999c60 MK |
165 | tp = tcp_drop(tp, tp->t_softerror ? |
166 | tp->t_softerror : ETIMEDOUT); | |
0e3936fa | 167 | break; |
fd5dc5f0 | 168 | } |
35f3fc10 | 169 | tcpstat.tcps_rexmttimeo++; |
7d999c60 MK |
170 | rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift]; |
171 | TCPT_RANGESET(tp->t_rxtcur, rexmt, | |
172 | tp->t_rttmin, TCPTV_REXMTMAX); | |
a6bbda13 | 173 | tp->t_timer[TCPT_REXMT] = tp->t_rxtcur; |
6a4fd140 | 174 | /* |
a6bbda13 MK |
175 | * If losing, let the lower level know and try for |
176 | * a better route. Also, if we backed off this far, | |
177 | * our srtt estimate is probably bogus. Clobber it | |
178 | * so we'll take the next rtt measurement as our srtt; | |
179 | * move the current srtt into rttvar to keep the current | |
180 | * retransmit times until then. | |
6a4fd140 | 181 | */ |
a6bbda13 | 182 | if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) { |
9d866d2f | 183 | #if BSD>=43 |
6a4fd140 | 184 | in_losing(tp->t_inpcb); |
9d866d2f | 185 | #endif |
7d999c60 | 186 | tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT); |
a6bbda13 MK |
187 | tp->t_srtt = 0; |
188 | } | |
405c9168 | 189 | tp->snd_nxt = tp->snd_una; |
7872cc0a | 190 | /* |
7cc62c26 | 191 | * If timing a segment in this window, stop the timer. |
7872cc0a | 192 | */ |
7cc62c26 | 193 | tp->t_rtt = 0; |
2e5a76f2 MK |
194 | /* |
195 | * Close the congestion window down to one segment | |
196 | * (we'll open it by one segment for each ack we get). | |
197 | * Since we probably have a window's worth of unacked | |
198 | * data accumulated, this "slow start" keeps us from | |
199 | * dumping all that data as back-to-back packets (which | |
200 | * might overwhelm an intermediate gateway). | |
6f854ef4 MK |
201 | * |
202 | * There are two phases to the opening: Initially we | |
203 | * open by one mss on each ack. This makes the window | |
204 | * size increase exponentially with time. If the | |
205 | * window is larger than the path can handle, this | |
206 | * exponential growth results in dropped packet(s) | |
207 | * almost immediately. To get more time between | |
208 | * drops but still "push" the network to take advantage | |
209 | * of improving conditions, we switch from exponential | |
210 | * to linear window opening at some threshhold size. | |
211 | * For a threshhold, we use half the current window | |
212 | * size, truncated to a multiple of the mss. | |
213 | * | |
214 | * (the minimum cwnd that will give us exponential | |
215 | * growth is 2 mss. We don't allow the threshhold | |
216 | * to go below this.) | |
2e5a76f2 | 217 | */ |
6f854ef4 | 218 | { |
7d999c60 | 219 | u_int win = min(tp->snd_wnd, tp->snd_cwnd) / 2 / tp->t_maxseg; |
6f854ef4 MK |
220 | if (win < 2) |
221 | win = 2; | |
2e5a76f2 | 222 | tp->snd_cwnd = tp->t_maxseg; |
6f854ef4 | 223 | tp->snd_ssthresh = win * tp->t_maxseg; |
7d999c60 | 224 | tp->t_dupacks = 0; |
6f854ef4 | 225 | } |
405c9168 | 226 | (void) tcp_output(tp); |
0e3936fa | 227 | break; |
f03530e6 | 228 | |
405c9168 BJ |
229 | /* |
230 | * Persistance timer into zero window. | |
231 | * Force a byte to be output, if possible. | |
232 | */ | |
a6503abf | 233 | case TCPT_PERSIST: |
35f3fc10 | 234 | tcpstat.tcps_persisttimeo++; |
a13c006d | 235 | tcp_setpersist(tp); |
405c9168 BJ |
236 | tp->t_force = 1; |
237 | (void) tcp_output(tp); | |
238 | tp->t_force = 0; | |
0e3936fa | 239 | break; |
f03530e6 | 240 | |
405c9168 BJ |
241 | /* |
242 | * Keep-alive timer went off; send something | |
243 | * or drop connection if idle for too long. | |
244 | */ | |
a6503abf | 245 | case TCPT_KEEP: |
35f3fc10 | 246 | tcpstat.tcps_keeptimeo++; |
f3cdd721 BJ |
247 | if (tp->t_state < TCPS_ESTABLISHED) |
248 | goto dropit; | |
c0200c65 MK |
249 | if (tp->t_inpcb->inp_socket->so_options & SO_KEEPALIVE && |
250 | tp->t_state <= TCPS_CLOSE_WAIT) { | |
8a36cf82 | 251 | if (tp->t_idle >= tcp_keepidle + tcp_maxidle) |
f3cdd721 | 252 | goto dropit; |
3bd14c98 | 253 | /* |
35f3fc10 MK |
254 | * Send a packet designed to force a response |
255 | * if the peer is up and reachable: | |
256 | * either an ACK if the connection is still alive, | |
257 | * or an RST if the peer has closed the connection | |
258 | * due to timeout or reboot. | |
259 | * Using sequence number tp->snd_una-1 | |
260 | * causes the transmitted zero-length segment | |
261 | * to lie outside the receive window; | |
262 | * by the protocol spec, this requires the | |
263 | * correspondent TCP to respond. | |
3bd14c98 | 264 | */ |
35f3fc10 | 265 | tcpstat.tcps_keepprobe++; |
eeef4ac3 MK |
266 | #ifdef TCP_COMPAT_42 |
267 | /* | |
268 | * The keepalive packet must have nonzero length | |
269 | * to get a 4.2 host to respond. | |
270 | */ | |
cc072043 | 271 | tcp_respond(tp, tp->t_template, (struct mbuf *)NULL, |
eeef4ac3 MK |
272 | tp->rcv_nxt - 1, tp->snd_una - 1, 0); |
273 | #else | |
cc072043 | 274 | tcp_respond(tp, tp->t_template, (struct mbuf *)NULL, |
eeef4ac3 MK |
275 | tp->rcv_nxt, tp->snd_una - 1, 0); |
276 | #endif | |
8a36cf82 MK |
277 | tp->t_timer[TCPT_KEEP] = tcp_keepintvl; |
278 | } else | |
279 | tp->t_timer[TCPT_KEEP] = tcp_keepidle; | |
0e3936fa | 280 | break; |
f3cdd721 | 281 | dropit: |
35f3fc10 | 282 | tcpstat.tcps_keepdrops++; |
0e3936fa SL |
283 | tp = tcp_drop(tp, ETIMEDOUT); |
284 | break; | |
f03530e6 | 285 | } |
0e3936fa | 286 | return (tp); |
f03530e6 | 287 | } |
55ad7758 | 288 | #endif /* TUBA_INCLUDE */ |