tcp_sack.c revision 1.7
1 /* $NetBSD: tcp_sack.c,v 1.7 2005/03/07 10:27:39 yamt Exp $ */ 2 3 /* 4 * Copyright (c) 2005 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Kentaro A. Kurahone. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the NetBSD 21 * Foundation, Inc. and its contributors. 22 * 4. Neither the name of The NetBSD Foundation nor the names of its 23 * contributors may be used to endorse or promote products derived 24 * from this software without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 29 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 36 * POSSIBILITY OF SUCH DAMAGE. 37 */ 38 39 /* 40 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995 41 * The Regents of the University of California. All rights reserved. 42 * 43 * Redistribution and use in source and binary forms, with or without 44 * modification, are permitted provided that the following conditions 45 * are met: 46 * 1. Redistributions of source code must retain the above copyright 47 * notice, this list of conditions and the following disclaimer. 48 * 2. Redistributions in binary form must reproduce the above copyright 49 * notice, this list of conditions and the following disclaimer in the 50 * documentation and/or other materials provided with the distribution. 51 * 4. Neither the name of the University nor the names of its contributors 52 * may be used to endorse or promote products derived from this software 53 * without specific prior written permission. 54 * 55 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 56 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 57 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 58 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 59 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 60 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 61 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 62 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 63 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 64 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 65 * SUCH DAMAGE. 66 * 67 * @(#)tcp_sack.c 8.12 (Berkeley) 5/24/95 68 * $FreeBSD: src/sys/netinet/tcp_sack.c,v 1.3.2.2 2004/12/25 23:02:57 rwatson Exp $ 69 */ 70 71 /* 72 * @@(#)COPYRIGHT 1.1 (NRL) 17 January 1995 73 * 74 * NRL grants permission for redistribution and use in source and binary 75 * forms, with or without modification, of the software and documentation 76 * created at NRL provided that the following conditions are met: 77 * 78 * 1. Redistributions of source code must retain the above copyright 79 * notice, this list of conditions and the following disclaimer. 80 * 2. Redistributions in binary form must reproduce the above copyright 81 * notice, this list of conditions and the following disclaimer in the 82 * documentation and/or other materials provided with the distribution. 83 * 3. All advertising materials mentioning features or use of this software 84 * must display the following acknowledgements: 85 * This product includes software developed by the University of 86 * California, Berkeley and its contributors. 87 * This product includes software developed at the Information 88 * Technology Division, US Naval Research Laboratory. 89 * 4. Neither the name of the NRL nor the names of its contributors 90 * may be used to endorse or promote products derived from this software 91 * without specific prior written permission. 92 * 93 * THE SOFTWARE PROVIDED BY NRL IS PROVIDED BY NRL AND CONTRIBUTORS ``AS 94 * IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 95 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A 96 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL NRL OR 97 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 98 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 99 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 100 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF 101 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 102 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 103 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 104 * 105 * The views and conclusions contained in the software and documentation 106 * are those of the authors and should not be interpreted as representing 107 * official policies, either expressed or implied, of the US Naval 108 * Research Laboratory (NRL). 109 */ 110 111 #include <sys/cdefs.h> 112 __KERNEL_RCSID(0, "$NetBSD: tcp_sack.c,v 1.7 2005/03/07 10:27:39 yamt Exp $"); 113 114 #include "opt_inet.h" 115 #include "opt_ipsec.h" 116 #include "opt_inet_csum.h" 117 #include "opt_tcp_debug.h" 118 119 #include <sys/param.h> 120 #include <sys/systm.h> 121 #include <sys/malloc.h> 122 #include <sys/mbuf.h> 123 #include <sys/protosw.h> 124 #include <sys/socket.h> 125 #include <sys/socketvar.h> 126 #include <sys/errno.h> 127 #include <sys/syslog.h> 128 #include <sys/pool.h> 129 #include <sys/domain.h> 130 #include <sys/kernel.h> 131 132 #include <net/if.h> 133 #include <net/route.h> 134 #include <net/if_types.h> 135 136 #include <netinet/in.h> 137 #include <netinet/in_systm.h> 138 #include <netinet/ip.h> 139 #include <netinet/in_pcb.h> 140 #include <netinet/in_var.h> 141 #include <netinet/ip_var.h> 142 143 #ifdef INET6 144 #ifndef INET 145 #include <netinet/in.h> 146 #endif 147 #include <netinet/ip6.h> 148 #include <netinet6/ip6_var.h> 149 #include <netinet6/in6_pcb.h> 150 #include <netinet6/ip6_var.h> 151 #include <netinet6/in6_var.h> 152 #include <netinet/icmp6.h> 153 #include <netinet6/nd6.h> 154 #endif 155 156 #ifndef INET6 157 /* always need ip6.h for IP6_EXTHDR_GET */ 158 #include <netinet/ip6.h> 159 #endif 160 161 #include <netinet/tcp.h> 162 #include <netinet/tcp_fsm.h> 163 #include <netinet/tcp_seq.h> 164 #include <netinet/tcp_timer.h> 165 #include <netinet/tcp_var.h> 166 #include <netinet/tcpip.h> 167 #include <netinet/tcp_debug.h> 168 169 #include <machine/stdarg.h> 170 171 #define SEQ_MIN(a, b) ((SEQ_LT(a, b)) ? (a) : (b)) 172 #define SEQ_MAX(a, b) ((SEQ_GT(a, b)) ? (a) : (b)) 173 174 /* SACK block pool. */ 175 POOL_INIT(sackhole_pool, sizeof(struct sackhole), 0, 0, 0, "sackholepl", NULL); 176 177 void 178 tcp_update_sack_list(struct tcpcb *tp) 179 { 180 int i = 0; 181 struct ipqent *tiqe = NULL; 182 183 if (!TCP_SACK_ENABLED(tp) || (tp->t_flags & TF_SIGNATURE)) { 184 /* Can't SACK this connection. */ 185 return; 186 } 187 188 /* 189 * If possible, tack on the D-SACK block. (RFC2883) 190 */ 191 if (tp->rcv_sack_flags & TCPSACK_HAVED) { 192 tp->rcv_sack_block[0].left = tp->rcv_dsack_block.left; 193 tp->rcv_sack_block[0].right = tp->rcv_dsack_block.right; 194 tp->rcv_sack_flags &= ~TCPSACK_HAVED; 195 i++; 196 } 197 198 /* 199 * Build up a list of holes in the TCP space. Note that 200 * the first SACK block is always the most recent segment 201 * received. 202 */ 203 TAILQ_FOREACH(tiqe, &tp->timeq, ipqe_timeq) { 204 tp->rcv_sack_block[i].left = tiqe->ipqe_seq; 205 tp->rcv_sack_block[i].right = tiqe->ipqe_seq + tiqe->ipqe_len; 206 i++; 207 if (i >= TCP_SACK_MAX) { 208 break; 209 } 210 } 211 212 /* If we can SACK, do so. */ 213 tp->rcv_sack_num = i; 214 } 215 216 void 217 tcp_new_dsack(struct tcpcb *tp, tcp_seq seq, u_int32_t len) 218 { 219 if (TCP_SACK_ENABLED(tp)) { 220 tp->rcv_dsack_block.left = seq; 221 tp->rcv_dsack_block.right = seq + len; 222 tp->rcv_sack_flags |= TCPSACK_HAVED; 223 } 224 } 225 226 void 227 tcp_sack_option(struct tcpcb *tp, struct tcphdr *th, u_char *cp, int optlen) 228 { 229 struct sackblk 230 t_sack_block[(MAX_TCPOPTLEN - 2) / (sizeof(u_int32_t) * 2)]; 231 struct sackblk *sack = NULL; 232 struct sackhole *cur = NULL; 233 struct sackhole *tmp = NULL; 234 u_int32_t *lp = (u_int32_t *) (cp + 2); 235 int i, j, num_sack_blks; 236 tcp_seq left, right, acked; 237 238 /* 239 * If we aren't processing SACK responses, or the peer 240 * sends us a sack option with invalid length, don't 241 * update the scoreboard. 242 */ 243 if (!TCP_SACK_ENABLED(tp) || (optlen % 8 != 2 || optlen < 10)) { 244 return; 245 } 246 247 /* 248 * Extract SACK blocks. 249 * 250 * Note that t_sack_block is sorted so that we only need to do 251 * one pass over the sequence number space. (SACK "fast-path") 252 */ 253 num_sack_blks = optlen / 8; 254 acked = (SEQ_GT(th->th_ack, tp->snd_una)) ? th->th_ack : tp->snd_una; 255 for (i = 0; i < num_sack_blks; i++, lp += 2) { 256 memcpy(&left, lp, sizeof(*lp)); 257 memcpy(&right, lp + 1, sizeof(*lp)); 258 left = ntohl(left); 259 right = ntohl(right); 260 261 if (SEQ_LEQ(right, acked) || SEQ_GEQ(left, tp->snd_max) || 262 SEQ_GEQ(left, right)) { 263 /* SACK entry that's old, or invalid. */ 264 i--; 265 num_sack_blks--; 266 continue; 267 } 268 269 /* Insertion sort. */ 270 for (j = i; (j > 0) && SEQ_LT(left, t_sack_block[j - 1].left); 271 j--) { 272 t_sack_block[j].left = t_sack_block[j - 1].left; 273 t_sack_block[j].right = t_sack_block[j - 1].right; 274 } 275 t_sack_block[j].left = left; 276 t_sack_block[j].right = right; 277 } 278 279 /* Update the scoreboard. */ 280 cur = TAILQ_FIRST(&tp->snd_holes); 281 for (i = 0; i < num_sack_blks; i++) { 282 sack = &t_sack_block[i]; 283 /* 284 * FACK TCP. Update snd_fack so we can enter Fast 285 * Recovery early. 286 */ 287 if (SEQ_GEQ(sack->right, tp->snd_fack)) 288 tp->snd_fack = sack->right; 289 290 if (TAILQ_EMPTY(&tp->snd_holes)) { 291 /* First hole. */ 292 cur = (struct sackhole *) 293 pool_get(&sackhole_pool, PR_NOWAIT); 294 if (cur == NULL) { 295 /* ENOBUFS, bail out*/ 296 return; 297 } 298 cur->start = th->th_ack; 299 cur->end = sack->left; 300 cur->rxmit = cur->start; 301 tp->rcv_lastsack = sack->right; 302 TAILQ_INSERT_HEAD(&tp->snd_holes, cur, sackhole_q); 303 continue; /* With next sack block */ 304 } 305 306 /* Go through the list of holes. */ 307 while (cur) { 308 if (SEQ_LEQ(sack->right, cur->start)) 309 /* SACKs data before the current hole */ 310 break; /* No use going through more holes */ 311 312 if (SEQ_GEQ(sack->left, cur->end)) { 313 /* SACKs data beyond the current hole */ 314 cur = TAILQ_NEXT(cur, sackhole_q); 315 continue; 316 } 317 318 if (SEQ_LEQ(sack->left, cur->start)) { 319 /* Data acks at least the beginning of hole */ 320 if (SEQ_GEQ(sack->right, cur->end)) { 321 /* Acks entire hole, so delete hole */ 322 tmp = cur; 323 cur = TAILQ_NEXT(cur, sackhole_q); 324 TAILQ_REMOVE(&tp->snd_holes, tmp, 325 sackhole_q); 326 pool_put(&sackhole_pool, tmp); 327 break; 328 } 329 330 /* Otherwise, move start of hole forward */ 331 cur->start = sack->right; 332 cur->rxmit = SEQ_MAX(cur->rxmit, cur->start); 333 break; 334 } 335 336 if (SEQ_GEQ(sack->right, cur->end)) { 337 /* Move end of hole backward. */ 338 cur->end = sack->left; 339 cur->rxmit = SEQ_MIN(cur->rxmit, cur->end); 340 cur = TAILQ_NEXT(cur, sackhole_q); 341 break; 342 } 343 344 if (SEQ_LT(cur->start, sack->left) && 345 SEQ_GT(cur->end, sack->right)) { 346 /* 347 * ACKs some data in middle of a hole; need to 348 * split current hole 349 */ 350 tmp = (struct sackhole *) 351 pool_get(&sackhole_pool, PR_NOWAIT); 352 if (tmp == NULL) { 353 /* ENOBUFS, bail out. */ 354 return; 355 } 356 tmp->start = sack->right; 357 tmp->end = cur->end; 358 tmp->rxmit = SEQ_MAX(cur->rxmit, tmp->start); 359 cur->end = sack->left; 360 cur->rxmit = SEQ_MIN(cur->rxmit, cur->end); 361 TAILQ_INSERT_AFTER(&tp->snd_holes, cur, tmp, 362 sackhole_q); 363 cur = tmp; 364 break; 365 } 366 } 367 368 /* At this point, we have reached the tail of the list. */ 369 if (SEQ_LT(tp->rcv_lastsack, sack->left)) { 370 /* 371 * Need to append new hole at end. 372 */ 373 tmp = (struct sackhole *) 374 pool_get(&sackhole_pool, PR_NOWAIT); 375 if (tmp == NULL) 376 continue; /* ENOBUFS */ 377 tmp->start = tp->rcv_lastsack; 378 tmp->end = sack->left; 379 tmp->rxmit = tmp->start; 380 tp->rcv_lastsack = sack->right; 381 TAILQ_INSERT_TAIL(&tp->snd_holes, tmp, sackhole_q); 382 cur = tmp; 383 } 384 } 385 } 386 387 void 388 tcp_del_sackholes(struct tcpcb *tp, struct tcphdr *th) 389 { 390 /* Max because this could be an older ack that just arrived. */ 391 tcp_seq lastack = SEQ_GT(th->th_ack, tp->snd_una) ? 392 th->th_ack : tp->snd_una; 393 struct sackhole *cur = TAILQ_FIRST(&tp->snd_holes); 394 struct sackhole *tmp; 395 396 while (cur) { 397 if (SEQ_LEQ(cur->end, lastack)) { 398 tmp = cur; 399 cur = TAILQ_NEXT(cur, sackhole_q); 400 TAILQ_REMOVE(&tp->snd_holes, tmp, sackhole_q); 401 pool_put(&sackhole_pool, tmp); 402 } else if (SEQ_LT(cur->start, lastack)) { 403 cur->start = lastack; 404 if (SEQ_LT(cur->rxmit, cur->start)) 405 cur->rxmit = cur->start; 406 break; 407 } else 408 break; 409 410 } 411 } 412 413 void 414 tcp_free_sackholes(struct tcpcb *tp) 415 { 416 struct sackhole *sack; 417 418 /* Free up the SACK hole list. */ 419 while (!TAILQ_EMPTY(&tp->snd_holes)) { 420 sack = TAILQ_FIRST(&tp->snd_holes); 421 TAILQ_REMOVE(&tp->snd_holes, sack, sackhole_q); 422 pool_put(&sackhole_pool, sack); 423 } 424 } 425 426 /* 427 * Implements the SACK response to a new ack, checking for partial acks 428 * in fast recovery. 429 */ 430 void 431 tcp_sack_newack(struct tcpcb *tp, struct tcphdr *th) 432 { 433 if (tp->t_partialacks < 0) { 434 /* 435 * Not in fast recovery. Reset the duplicate ack 436 * counter. 437 */ 438 tp->t_dupacks = 0; 439 } else if (SEQ_LT(th->th_ack, tp->snd_recover)) { 440 /* 441 * Partial ack handling within a sack recovery episode. 442 * Keeping this very simple for now. When a partial ack 443 * is received, force snd_cwnd to a value that will allow 444 * the sender to transmit no more than 2 segments. 445 * If necessary, a fancier scheme can be adopted at a 446 * later point, but for now, the goal is to prevent the 447 * sender from bursting a large amount of data in the midst 448 * of sack recovery. 449 */ 450 int num_segs = 1; 451 int sack_bytes_rxmt = 0; 452 453 tp->t_partialacks++; 454 TCP_TIMER_DISARM(tp, TCPT_REXMT); 455 tp->t_rtttime = 0; 456 457 /* 458 * send one or 2 segments based on how much new data was acked 459 */ 460 if (((th->th_ack - tp->snd_una) / tp->t_segsz) > 2) 461 num_segs = 2; 462 (void)tcp_sack_output(tp, &sack_bytes_rxmt); 463 tp->snd_cwnd = sack_bytes_rxmt + 464 (tp->snd_nxt - tp->sack_newdata) + num_segs * tp->t_segsz; 465 tp->t_flags |= TF_ACKNOW; 466 (void) tcp_output(tp); 467 } else { 468 /* 469 * Complete ack, inflate the congestion window to 470 * ssthresh and exit fast recovery. 471 * 472 * Window inflation should have left us with approx. 473 * snd_ssthresh outstanding data. But in case we 474 * would be inclined to send a burst, better to do 475 * it via the slow start mechanism. 476 */ 477 if (SEQ_SUB(tp->snd_max, th->th_ack) < tp->snd_ssthresh) 478 tp->snd_cwnd = SEQ_SUB(tp->snd_max, th->th_ack) 479 + tp->t_segsz; 480 else 481 tp->snd_cwnd = tp->snd_ssthresh; 482 tp->t_partialacks = -1; 483 tp->t_dupacks = 0; 484 if (SEQ_GT(th->th_ack, tp->snd_fack)) 485 tp->snd_fack = th->th_ack; 486 } 487 } 488 489 /* 490 * Returns pointer to a sackhole if there are any pending retransmissions; 491 * NULL otherwise. 492 */ 493 struct sackhole * 494 tcp_sack_output(struct tcpcb *tp, int *sack_bytes_rexmt) 495 { 496 struct sackhole *cur = NULL; 497 498 if(!TCP_SACK_ENABLED(tp)) 499 return (NULL); 500 501 *sack_bytes_rexmt = 0; 502 TAILQ_FOREACH(cur, &tp->snd_holes, sackhole_q) { 503 if (SEQ_LT(cur->rxmit, cur->end)) { 504 if (SEQ_LT(cur->rxmit, tp->snd_una)) { 505 /* old SACK hole */ 506 continue; 507 } 508 *sack_bytes_rexmt += (cur->rxmit - cur->start); 509 break; 510 } 511 *sack_bytes_rexmt += (cur->rxmit - cur->start); 512 } 513 514 return (cur); 515 } 516 517 /* 518 * After a timeout, the SACK list may be rebuilt. This SACK information 519 * should be used to avoid retransmitting SACKed data. This function 520 * traverses the SACK list to see if snd_nxt should be moved forward. 521 */ 522 void 523 tcp_sack_adjust(struct tcpcb *tp) 524 { 525 struct sackhole *cur = TAILQ_FIRST(&tp->snd_holes); 526 struct sackhole *n = NULL; 527 528 if (TAILQ_EMPTY(&tp->snd_holes)) 529 return; /* No holes */ 530 if (SEQ_GEQ(tp->snd_nxt, tp->rcv_lastsack)) 531 return; /* We're already beyond any SACKed blocks */ 532 533 /* 534 * Two cases for which we want to advance snd_nxt: 535 * i) snd_nxt lies between end of one hole and beginning of another 536 * ii) snd_nxt lies between end of last hole and rcv_lastsack 537 */ 538 while ((n = TAILQ_NEXT(cur, sackhole_q)) != NULL) { 539 if (SEQ_LT(tp->snd_nxt, cur->end)) 540 return; 541 if (SEQ_GEQ(tp->snd_nxt, n->start)) 542 cur = n; 543 else { 544 tp->snd_nxt = n->start; 545 return; 546 } 547 } 548 if (SEQ_LT(tp->snd_nxt, cur->end)) 549 return; 550 tp->snd_nxt = tp->rcv_lastsack; 551 552 return; 553 } 554
Indexes created Wed Sep 24 05:09:52 GMT 2025