The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (c) 1982, 1986, 1988, 1990, 1993 |
| 3 | * The Regents of the University of California. All rights reserved. |
| 4 | * |
| 5 | * Redistribution and use in source and binary forms, with or without |
| 6 | * modification, are permitted provided that the following conditions |
| 7 | * are met: |
| 8 | * 1. Redistributions of source code must retain the above copyright |
| 9 | * notice, this list of conditions and the following disclaimer. |
| 10 | * 2. Redistributions in binary form must reproduce the above copyright |
| 11 | * notice, this list of conditions and the following disclaimer in the |
| 12 | * documentation and/or other materials provided with the distribution. |
David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 13 | * 3. Neither the name of the University nor the names of its contributors |
The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 14 | * may be used to endorse or promote products derived from this software |
| 15 | * without specific prior written permission. |
| 16 | * |
| 17 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
| 18 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 19 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 20 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
| 21 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| 22 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| 23 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 24 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| 25 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| 26 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 27 | * SUCH DAMAGE. |
| 28 | * |
| 29 | * @(#)tcp_timer.c 8.1 (Berkeley) 6/10/93 |
| 30 | * tcp_timer.c,v 1.2 1994/08/02 07:49:10 davidg Exp |
| 31 | */ |
| 32 | |
| 33 | #include <slirp.h> |
| 34 | |
David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 35 | #ifdef LOG_ENABLED |
The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 36 | struct tcpstat tcpstat; /* tcp statistics */ |
David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 37 | #endif |
| 38 | |
The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 39 | u_int32_t tcp_now; /* for RFC 1323 timestamps */ |
| 40 | |
David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 41 | static struct tcpcb *tcp_timers(register struct tcpcb *tp, int timer); |
| 42 | |
The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 43 | /* |
| 44 | * Fast timeout routine for processing delayed acks |
| 45 | */ |
| 46 | void |
David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 47 | tcp_fasttimo(void) |
The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 48 | { |
| 49 | register struct socket *so; |
| 50 | register struct tcpcb *tp; |
| 51 | |
| 52 | DEBUG_CALL("tcp_fasttimo"); |
David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 53 | |
The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 54 | so = tcb.so_next; |
| 55 | if (so) |
| 56 | for (; so != &tcb; so = so->so_next) |
| 57 | if ((tp = (struct tcpcb *)so->so_tcpcb) && |
| 58 | (tp->t_flags & TF_DELACK)) { |
| 59 | tp->t_flags &= ~TF_DELACK; |
| 60 | tp->t_flags |= TF_ACKNOW; |
David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 61 | STAT(tcpstat.tcps_delack++); |
The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 62 | (void) tcp_output(tp); |
| 63 | } |
| 64 | } |
| 65 | |
| 66 | /* |
| 67 | * Tcp protocol timeout routine called every 500 ms. |
| 68 | * Updates the timers in all active tcb's and |
| 69 | * causes finite state machine actions if timers expire. |
| 70 | */ |
| 71 | void |
David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 72 | tcp_slowtimo(void) |
The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 73 | { |
| 74 | register struct socket *ip, *ipnxt; |
| 75 | register struct tcpcb *tp; |
| 76 | register int i; |
| 77 | |
| 78 | DEBUG_CALL("tcp_slowtimo"); |
David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 79 | |
The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 80 | /* |
| 81 | * Search through tcb's and update active timers. |
| 82 | */ |
| 83 | ip = tcb.so_next; |
| 84 | if (ip == 0) |
| 85 | return; |
| 86 | for (; ip != &tcb; ip = ipnxt) { |
| 87 | ipnxt = ip->so_next; |
| 88 | tp = sototcpcb(ip); |
| 89 | if (tp == 0) |
| 90 | continue; |
| 91 | for (i = 0; i < TCPT_NTIMERS; i++) { |
| 92 | if (tp->t_timer[i] && --tp->t_timer[i] == 0) { |
| 93 | tcp_timers(tp,i); |
| 94 | if (ipnxt->so_prev != ip) |
| 95 | goto tpgone; |
| 96 | } |
| 97 | } |
| 98 | tp->t_idle++; |
| 99 | if (tp->t_rtt) |
| 100 | tp->t_rtt++; |
| 101 | tpgone: |
| 102 | ; |
| 103 | } |
| 104 | tcp_iss += TCP_ISSINCR/PR_SLOWHZ; /* increment iss */ |
| 105 | #ifdef TCP_COMPAT_42 |
| 106 | if ((int)tcp_iss < 0) |
| 107 | tcp_iss = 0; /* XXX */ |
| 108 | #endif |
| 109 | tcp_now++; /* for timestamps */ |
| 110 | } |
| 111 | |
| 112 | /* |
| 113 | * Cancel all timers for TCP tp. |
| 114 | */ |
| 115 | void |
David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 116 | tcp_canceltimers(struct tcpcb *tp) |
The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 117 | { |
| 118 | register int i; |
| 119 | |
| 120 | for (i = 0; i < TCPT_NTIMERS; i++) |
| 121 | tp->t_timer[i] = 0; |
| 122 | } |
| 123 | |
David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 124 | const int tcp_backoff[TCP_MAXRXTSHIFT + 1] = |
The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 125 | { 1, 2, 4, 8, 16, 32, 64, 64, 64, 64, 64, 64, 64 }; |
| 126 | |
| 127 | /* |
| 128 | * TCP timer processing. |
| 129 | */ |
David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 130 | static struct tcpcb * |
| 131 | tcp_timers(register struct tcpcb *tp, int timer) |
The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 132 | { |
| 133 | register int rexmt; |
David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 134 | |
The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 135 | DEBUG_CALL("tcp_timers"); |
David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 136 | |
The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 137 | switch (timer) { |
| 138 | |
| 139 | /* |
| 140 | * 2 MSL timeout in shutdown went off. If we're closed but |
| 141 | * still waiting for peer to close and connection has been idle |
| 142 | * too long, or if 2MSL time is up from TIME_WAIT, delete connection |
| 143 | * control block. Otherwise, check again in a bit. |
| 144 | */ |
| 145 | case TCPT_2MSL: |
| 146 | if (tp->t_state != TCPS_TIME_WAIT && |
David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 147 | tp->t_idle <= TCP_MAXIDLE) |
| 148 | tp->t_timer[TCPT_2MSL] = TCPTV_KEEPINTVL; |
The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 149 | else |
| 150 | tp = tcp_close(tp); |
| 151 | break; |
| 152 | |
| 153 | /* |
| 154 | * Retransmission timer went off. Message has not |
| 155 | * been acked within retransmit interval. Back off |
| 156 | * to a longer retransmit interval and retransmit one segment. |
| 157 | */ |
| 158 | case TCPT_REXMT: |
David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 159 | |
The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 160 | /* |
| 161 | * XXXXX If a packet has timed out, then remove all the queued |
| 162 | * packets for that session. |
| 163 | */ |
David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 164 | |
The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 165 | if (++tp->t_rxtshift > TCP_MAXRXTSHIFT) { |
| 166 | /* |
| 167 | * This is a hack to suit our terminal server here at the uni of canberra |
| 168 | * since they have trouble with zeroes... It usually lets them through |
| 169 | * unharmed, but under some conditions, it'll eat the zeros. If we |
| 170 | * keep retransmitting it, it'll keep eating the zeroes, so we keep |
| 171 | * retransmitting, and eventually the connection dies... |
| 172 | * (this only happens on incoming data) |
David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 173 | * |
The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 174 | * So, if we were gonna drop the connection from too many retransmits, |
| 175 | * don't... instead halve the t_maxseg, which might break up the NULLs and |
| 176 | * let them through |
David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 177 | * |
The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 178 | * *sigh* |
| 179 | */ |
David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 180 | |
The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 181 | tp->t_maxseg >>= 1; |
| 182 | if (tp->t_maxseg < 32) { |
| 183 | /* |
| 184 | * We tried our best, now the connection must die! |
| 185 | */ |
| 186 | tp->t_rxtshift = TCP_MAXRXTSHIFT; |
David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 187 | STAT(tcpstat.tcps_timeoutdrop++); |
The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 188 | tp = tcp_drop(tp, tp->t_softerror); |
| 189 | /* tp->t_softerror : ETIMEDOUT); */ /* XXX */ |
| 190 | return (tp); /* XXX */ |
| 191 | } |
David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 192 | |
The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 193 | /* |
| 194 | * Set rxtshift to 6, which is still at the maximum |
| 195 | * backoff time |
| 196 | */ |
| 197 | tp->t_rxtshift = 6; |
| 198 | } |
David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 199 | STAT(tcpstat.tcps_rexmttimeo++); |
The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 200 | rexmt = TCP_REXMTVAL(tp) * tcp_backoff[tp->t_rxtshift]; |
| 201 | TCPT_RANGESET(tp->t_rxtcur, rexmt, |
| 202 | (short)tp->t_rttmin, TCPTV_REXMTMAX); /* XXX */ |
| 203 | tp->t_timer[TCPT_REXMT] = tp->t_rxtcur; |
| 204 | /* |
| 205 | * If losing, let the lower level know and try for |
| 206 | * a better route. Also, if we backed off this far, |
| 207 | * our srtt estimate is probably bogus. Clobber it |
| 208 | * so we'll take the next rtt measurement as our srtt; |
| 209 | * move the current srtt into rttvar to keep the current |
| 210 | * retransmit times until then. |
| 211 | */ |
| 212 | if (tp->t_rxtshift > TCP_MAXRXTSHIFT / 4) { |
| 213 | /* in_losing(tp->t_inpcb); */ |
| 214 | tp->t_rttvar += (tp->t_srtt >> TCP_RTT_SHIFT); |
| 215 | tp->t_srtt = 0; |
| 216 | } |
| 217 | tp->snd_nxt = tp->snd_una; |
| 218 | /* |
| 219 | * If timing a segment in this window, stop the timer. |
| 220 | */ |
| 221 | tp->t_rtt = 0; |
| 222 | /* |
| 223 | * Close the congestion window down to one segment |
| 224 | * (we'll open it by one segment for each ack we get). |
| 225 | * Since we probably have a window's worth of unacked |
| 226 | * data accumulated, this "slow start" keeps us from |
| 227 | * dumping all that data as back-to-back packets (which |
| 228 | * might overwhelm an intermediate gateway). |
| 229 | * |
| 230 | * There are two phases to the opening: Initially we |
| 231 | * open by one mss on each ack. This makes the window |
| 232 | * size increase exponentially with time. If the |
| 233 | * window is larger than the path can handle, this |
| 234 | * exponential growth results in dropped packet(s) |
David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 235 | * almost immediately. To get more time between |
The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 236 | * drops but still "push" the network to take advantage |
| 237 | * of improving conditions, we switch from exponential |
| 238 | * to linear window opening at some threshold size. |
| 239 | * For a threshold, we use half the current window |
| 240 | * size, truncated to a multiple of the mss. |
| 241 | * |
| 242 | * (the minimum cwnd that will give us exponential |
| 243 | * growth is 2 mss. We don't allow the threshold |
| 244 | * to go below this.) |
| 245 | */ |
| 246 | { |
| 247 | u_int win = min(tp->snd_wnd, tp->snd_cwnd) / 2 / tp->t_maxseg; |
| 248 | if (win < 2) |
| 249 | win = 2; |
| 250 | tp->snd_cwnd = tp->t_maxseg; |
| 251 | tp->snd_ssthresh = win * tp->t_maxseg; |
| 252 | tp->t_dupacks = 0; |
| 253 | } |
| 254 | (void) tcp_output(tp); |
| 255 | break; |
| 256 | |
| 257 | /* |
| 258 | * Persistence timer into zero window. |
| 259 | * Force a byte to be output, if possible. |
| 260 | */ |
| 261 | case TCPT_PERSIST: |
David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 262 | STAT(tcpstat.tcps_persisttimeo++); |
The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 263 | tcp_setpersist(tp); |
| 264 | tp->t_force = 1; |
| 265 | (void) tcp_output(tp); |
| 266 | tp->t_force = 0; |
| 267 | break; |
| 268 | |
| 269 | /* |
| 270 | * Keep-alive timer went off; send something |
| 271 | * or drop connection if idle for too long. |
| 272 | */ |
| 273 | case TCPT_KEEP: |
David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 274 | STAT(tcpstat.tcps_keeptimeo++); |
The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 275 | if (tp->t_state < TCPS_ESTABLISHED) |
| 276 | goto dropit; |
| 277 | |
| 278 | /* if (tp->t_socket->so_options & SO_KEEPALIVE && */ |
David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 279 | if ((SO_OPTIONS) && tp->t_state <= TCPS_CLOSE_WAIT) { |
| 280 | if (tp->t_idle >= TCPTV_KEEP_IDLE + TCP_MAXIDLE) |
The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 281 | goto dropit; |
| 282 | /* |
| 283 | * Send a packet designed to force a response |
| 284 | * if the peer is up and reachable: |
| 285 | * either an ACK if the connection is still alive, |
| 286 | * or an RST if the peer has closed the connection |
| 287 | * due to timeout or reboot. |
| 288 | * Using sequence number tp->snd_una-1 |
| 289 | * causes the transmitted zero-length segment |
| 290 | * to lie outside the receive window; |
| 291 | * by the protocol spec, this requires the |
| 292 | * correspondent TCP to respond. |
| 293 | */ |
David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 294 | STAT(tcpstat.tcps_keepprobe++); |
The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 295 | #ifdef TCP_COMPAT_42 |
| 296 | /* |
| 297 | * The keepalive packet must have nonzero length |
| 298 | * to get a 4.2 host to respond. |
| 299 | */ |
David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 300 | tcp_respond(tp, &tp->t_template, (struct mbuf *)NULL, |
The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 301 | tp->rcv_nxt - 1, tp->snd_una - 1, 0); |
| 302 | #else |
David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 303 | tcp_respond(tp, &tp->t_template, (struct mbuf *)NULL, |
The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 304 | tp->rcv_nxt, tp->snd_una - 1, 0); |
| 305 | #endif |
David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 306 | tp->t_timer[TCPT_KEEP] = TCPTV_KEEPINTVL; |
The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 307 | } else |
David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 308 | tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_IDLE; |
The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 309 | break; |
| 310 | |
| 311 | dropit: |
David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 312 | STAT(tcpstat.tcps_keepdrops++); |
The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 313 | tp = tcp_drop(tp, 0); /* ETIMEDOUT); */ |
| 314 | break; |
| 315 | } |
| 316 | |
| 317 | return (tp); |
| 318 | } |