tcp_sack.c revision 1.32
1 /* $NetBSD: tcp_sack.c,v 1.32 2015/08/24 22:21:26 pooka 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 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 /* 33 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995 34 * The Regents of the University of California. All rights reserved. 35 * 36 * Redistribution and use in source and binary forms, with or without 37 * modification, are permitted provided that the following conditions 38 * are met: 39 * 1. Redistributions of source code must retain the above copyright 40 * notice, this list of conditions and the following disclaimer. 41 * 2. Redistributions in binary form must reproduce the above copyright 42 * notice, this list of conditions and the following disclaimer in the 43 * documentation and/or other materials provided with the distribution. 44 * 4. Neither the name of the University nor the names of its contributors 45 * may be used to endorse or promote products derived from this software 46 * without specific prior written permission. 47 * 48 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 49 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 50 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 51 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 52 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 53 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 54 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 55 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 56 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 57 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 58 * SUCH DAMAGE. 59 * 60 * @(#)tcp_sack.c 8.12 (Berkeley) 5/24/95 61 * $FreeBSD: src/sys/netinet/tcp_sack.c,v 1.3.2.2 2004/12/25 23:02:57 rwatson Exp $ 62 */ 63 64 /* 65 * @@(#)COPYRIGHT 1.1 (NRL) 17 January 1995 66 * 67 * NRL grants permission for redistribution and use in source and binary 68 * forms, with or without modification, of the software and documentation 69 * created at NRL provided that the following conditions are met: 70 * 71 * 1. Redistributions of source code must retain the above copyright 72 * notice, this list of conditions and the following disclaimer. 73 * 2. Redistributions in binary form must reproduce the above copyright 74 * notice, this list of conditions and the following disclaimer in the 75 * documentation and/or other materials provided with the distribution. 76 * 3. All advertising materials mentioning features or use of this software 77 * must display the following acknowledgements: 78 * This product includes software developed by the University of 79 * California, Berkeley and its contributors. 80 * This product includes software developed at the Information 81 * Technology Division, US Naval Research Laboratory. 82 * 4. Neither the name of the NRL nor the names of its contributors 83 * may be used to endorse or promote products derived from this software 84 * without specific prior written permission. 85 * 86 * THE SOFTWARE PROVIDED BY NRL IS PROVIDED BY NRL AND CONTRIBUTORS ``AS 87 * IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 88 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A 89 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL NRL OR 90 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 91 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 92 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 93 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF 94 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 95 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 96 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 97 * 98 * The views and conclusions contained in the software and documentation 99 * are those of the authors and should not be interpreted as representing 100 * official policies, either expressed or implied, of the US Naval 101 * Research Laboratory (NRL). 102 */ 103 104 #include <sys/cdefs.h> 105 __KERNEL_RCSID(0, "$NetBSD: tcp_sack.c,v 1.32 2015/08/24 22:21:26 pooka Exp $"); 106 107 #ifdef _KERNEL_OPT 108 #include "opt_inet.h" 109 #include "opt_inet_csum.h" 110 #include "opt_tcp_debug.h" 111 #include "opt_ddb.h" 112 #endif 113 114 #include <sys/param.h> 115 #include <sys/systm.h> 116 #include <sys/mbuf.h> 117 #include <sys/protosw.h> 118 #include <sys/socket.h> 119 #include <sys/socketvar.h> 120 #include <sys/errno.h> 121 #include <sys/syslog.h> 122 #include <sys/pool.h> 123 #include <sys/domain.h> 124 #include <sys/kernel.h> 125 126 #include <net/if.h> 127 #include <net/route.h> 128 #include <net/if_types.h> 129 130 #include <netinet/in.h> 131 #include <netinet/in_systm.h> 132 #include <netinet/ip.h> 133 #include <netinet/in_pcb.h> 134 #include <netinet/in_var.h> 135 #include <netinet/ip_var.h> 136 137 #ifdef INET6 138 #ifndef INET 139 #include <netinet/in.h> 140 #endif 141 #include <netinet/ip6.h> 142 #include <netinet6/ip6_var.h> 143 #include <netinet6/in6_pcb.h> 144 #include <netinet6/ip6_var.h> 145 #include <netinet6/in6_var.h> 146 #include <netinet/icmp6.h> 147 #include <netinet6/nd6.h> 148 #endif 149 150 #ifndef INET6 151 /* always need ip6.h for IP6_EXTHDR_GET */ 152 #include <netinet/ip6.h> 153 #endif 154 155 #include <netinet/tcp.h> 156 #include <netinet/tcp_fsm.h> 157 #include <netinet/tcp_seq.h> 158 #include <netinet/tcp_timer.h> 159 #include <netinet/tcp_var.h> 160 #include <netinet/tcpip.h> 161 #include <netinet/tcp_debug.h> 162 163 /* SACK block pool. */ 164 static struct pool sackhole_pool; 165 166 void 167 tcp_sack_init(void) 168 { 169 170 pool_init(&sackhole_pool, sizeof(struct sackhole), 0, 0, 0, 171 "sackholepl", NULL, IPL_SOFTNET); 172 } 173 174 static struct sackhole * 175 sack_allochole(struct tcpcb *tp) 176 { 177 struct sackhole *hole; 178 179 if (tp->snd_numholes >= tcp_sack_tp_maxholes || 180 tcp_sack_globalholes >= tcp_sack_globalmaxholes) { 181 return NULL; 182 } 183 hole = pool_get(&sackhole_pool, PR_NOWAIT); 184 if (hole == NULL) { 185 return NULL; 186 } 187 tp->snd_numholes++; 188 tcp_sack_globalholes++; 189 190 return hole; 191 } 192 193 static struct sackhole * 194 sack_inserthole(struct tcpcb *tp, tcp_seq start, tcp_seq end, 195 struct sackhole *prev) 196 { 197 struct sackhole *hole; 198 199 hole = sack_allochole(tp); 200 if (hole == NULL) { 201 return NULL; 202 } 203 hole->start = hole->rxmit = start; 204 hole->end = end; 205 if (prev != NULL) { 206 TAILQ_INSERT_AFTER(&tp->snd_holes, prev, hole, sackhole_q); 207 } else { 208 TAILQ_INSERT_TAIL(&tp->snd_holes, hole, sackhole_q); 209 } 210 return hole; 211 } 212 213 static struct sackhole * 214 sack_removehole(struct tcpcb *tp, struct sackhole *hole) 215 { 216 struct sackhole *next; 217 218 next = TAILQ_NEXT(hole, sackhole_q); 219 tp->snd_numholes--; 220 tcp_sack_globalholes--; 221 TAILQ_REMOVE(&tp->snd_holes, hole, sackhole_q); 222 pool_put(&sackhole_pool, hole); 223 224 return next; 225 } 226 227 /* 228 * tcp_new_dsack: record the reception of a duplicated segment. 229 */ 230 231 void 232 tcp_new_dsack(struct tcpcb *tp, tcp_seq seq, u_int32_t len) 233 { 234 235 if (TCP_SACK_ENABLED(tp)) { 236 tp->rcv_dsack_block.left = seq; 237 tp->rcv_dsack_block.right = seq + len; 238 tp->rcv_sack_flags |= TCPSACK_HAVED; 239 } 240 } 241 242 /* 243 * tcp_sack_option: parse the given SACK option and update the scoreboard. 244 */ 245 246 void 247 tcp_sack_option(struct tcpcb *tp, const struct tcphdr *th, const u_char *cp, 248 int optlen) 249 { 250 struct sackblk 251 t_sack_block[(MAX_TCPOPTLEN - 2) / (sizeof(u_int32_t) * 2)]; 252 struct sackblk *sack = NULL; 253 struct sackhole *cur = NULL; 254 struct sackhole *tmp = NULL; 255 const char *lp = cp + 2; 256 int i, j, num_sack_blks; 257 tcp_seq left, right, acked; 258 259 /* 260 * If we aren't processing SACK responses, this is not an ACK 261 * or the peer sends us a sack option with invalid length, don't 262 * update the scoreboard. 263 */ 264 if (!TCP_SACK_ENABLED(tp) || ((th->th_flags & TH_ACK) == 0) || 265 (optlen % 8 != 2 || optlen < 10)) { 266 return; 267 } 268 269 /* 270 * If we don't want any SACK holes to be allocated, just return. 271 */ 272 if (tcp_sack_globalmaxholes == 0 || tcp_sack_tp_maxholes == 0) { 273 return; 274 } 275 276 /* If the ACK is outside [snd_una, snd_max], ignore the SACK options. */ 277 if (SEQ_LT(th->th_ack, tp->snd_una) || SEQ_GT(th->th_ack, tp->snd_max)) 278 return; 279 280 /* 281 * Extract SACK blocks. 282 * 283 * Note that t_sack_block is sorted so that we only need to do 284 * one pass over the sequence number space. (SACK "fast-path") 285 */ 286 num_sack_blks = optlen / 8; 287 acked = (SEQ_GT(th->th_ack, tp->snd_una)) ? th->th_ack : tp->snd_una; 288 for (i = 0; i < num_sack_blks; i++, lp += sizeof(uint32_t) * 2) { 289 memcpy(&left, lp, sizeof(uint32_t)); 290 memcpy(&right, lp + sizeof(uint32_t), sizeof(uint32_t)); 291 left = ntohl(left); 292 right = ntohl(right); 293 294 if (SEQ_LEQ(right, acked) || SEQ_GT(right, tp->snd_max) || 295 SEQ_GEQ(left, right)) { 296 /* SACK entry that's old, or invalid. */ 297 i--; 298 num_sack_blks--; 299 continue; 300 } 301 302 /* Insertion sort. */ 303 for (j = i; (j > 0) && SEQ_LT(left, t_sack_block[j - 1].left); 304 j--) { 305 t_sack_block[j].left = t_sack_block[j - 1].left; 306 t_sack_block[j].right = t_sack_block[j - 1].right; 307 } 308 t_sack_block[j].left = left; 309 t_sack_block[j].right = right; 310 } 311 312 /* Update the scoreboard. */ 313 cur = TAILQ_FIRST(&tp->snd_holes); 314 for (i = 0; i < num_sack_blks; i++) { 315 sack = &t_sack_block[i]; 316 /* 317 * FACK TCP. Update snd_fack so we can enter Fast 318 * Recovery early. 319 */ 320 if (SEQ_GEQ(sack->right, tp->snd_fack)) 321 tp->snd_fack = sack->right; 322 323 if (TAILQ_EMPTY(&tp->snd_holes)) { 324 /* First hole. */ 325 cur = sack_inserthole(tp, th->th_ack, sack->left, NULL); 326 if (cur == NULL) { 327 /* ENOBUFS, bail out*/ 328 return; 329 } 330 tp->rcv_lastsack = sack->right; 331 continue; /* With next sack block */ 332 } 333 334 /* Go through the list of holes. */ 335 while (cur) { 336 if (SEQ_LEQ(sack->right, cur->start)) 337 /* SACKs data before the current hole */ 338 break; /* No use going through more holes */ 339 340 if (SEQ_GEQ(sack->left, cur->end)) { 341 /* SACKs data beyond the current hole */ 342 cur = TAILQ_NEXT(cur, sackhole_q); 343 continue; 344 } 345 346 if (SEQ_LEQ(sack->left, cur->start)) { 347 /* Data acks at least the beginning of hole */ 348 if (SEQ_GEQ(sack->right, cur->end)) { 349 /* Acks entire hole, so delete hole */ 350 cur = sack_removehole(tp, cur); 351 break; 352 } 353 354 /* Otherwise, move start of hole forward */ 355 cur->start = sack->right; 356 cur->rxmit = SEQ_MAX(cur->rxmit, cur->start); 357 break; 358 } 359 360 if (SEQ_GEQ(sack->right, cur->end)) { 361 /* Move end of hole backward. */ 362 cur->end = sack->left; 363 cur->rxmit = SEQ_MIN(cur->rxmit, cur->end); 364 cur = TAILQ_NEXT(cur, sackhole_q); 365 break; 366 } 367 368 if (SEQ_LT(cur->start, sack->left) && 369 SEQ_GT(cur->end, sack->right)) { 370 /* 371 * ACKs some data in middle of a hole; need to 372 * split current hole 373 */ 374 tmp = sack_inserthole(tp, sack->right, cur->end, 375 cur); 376 if (tmp == NULL) { 377 return; 378 } 379 tmp->rxmit = SEQ_MAX(cur->rxmit, tmp->start); 380 cur->end = sack->left; 381 cur->rxmit = SEQ_MIN(cur->rxmit, cur->end); 382 cur = tmp; 383 break; 384 } 385 } 386 387 /* At this point, we have reached the tail of the list. */ 388 if (SEQ_LT(tp->rcv_lastsack, sack->left)) { 389 /* 390 * Need to append new hole at end. 391 */ 392 cur = sack_inserthole(tp, tp->rcv_lastsack, sack->left, 393 NULL); 394 if (cur == NULL) { 395 return; 396 } 397 } 398 if (SEQ_LT(tp->rcv_lastsack, sack->right)) { 399 tp->rcv_lastsack = sack->right; 400 } 401 } 402 } 403 404 /* 405 * tcp_del_sackholes: remove holes covered by a cumulative ACK. 406 */ 407 408 void 409 tcp_del_sackholes(struct tcpcb *tp, const struct tcphdr *th) 410 { 411 /* Max because this could be an older ack that just arrived. */ 412 tcp_seq lastack = SEQ_GT(th->th_ack, tp->snd_una) ? 413 th->th_ack : tp->snd_una; 414 struct sackhole *cur = TAILQ_FIRST(&tp->snd_holes); 415 416 while (cur) { 417 if (SEQ_LEQ(cur->end, lastack)) { 418 cur = sack_removehole(tp, cur); 419 } else if (SEQ_LT(cur->start, lastack)) { 420 cur->start = lastack; 421 if (SEQ_LT(cur->rxmit, cur->start)) 422 cur->rxmit = cur->start; 423 break; 424 } else 425 break; 426 } 427 } 428 429 /* 430 * tcp_free_sackholes: clear the scoreboard. 431 */ 432 433 void 434 tcp_free_sackholes(struct tcpcb *tp) 435 { 436 struct sackhole *sack; 437 438 /* Free up the SACK hole list. */ 439 while ((sack = TAILQ_FIRST(&tp->snd_holes)) != NULL) { 440 sack_removehole(tp, sack); 441 } 442 KASSERT(tp->snd_numholes == 0); 443 } 444 445 /* 446 * Returns pointer to a sackhole if there are any pending retransmissions; 447 * NULL otherwise. 448 */ 449 struct sackhole * 450 tcp_sack_output(struct tcpcb *tp, int *sack_bytes_rexmt) 451 { 452 struct sackhole *cur = NULL; 453 454 if (!TCP_SACK_ENABLED(tp)) 455 return (NULL); 456 457 *sack_bytes_rexmt = 0; 458 TAILQ_FOREACH(cur, &tp->snd_holes, sackhole_q) { 459 if (SEQ_LT(cur->rxmit, cur->end)) { 460 if (SEQ_LT(cur->rxmit, tp->snd_una)) { 461 /* old SACK hole */ 462 continue; 463 } 464 *sack_bytes_rexmt += (cur->rxmit - cur->start); 465 break; 466 } 467 *sack_bytes_rexmt += (cur->rxmit - cur->start); 468 } 469 470 return (cur); 471 } 472 473 /* 474 * After a timeout, the SACK list may be rebuilt. This SACK information 475 * should be used to avoid retransmitting SACKed data. This function 476 * traverses the SACK list to see if snd_nxt should be moved forward. 477 */ 478 void 479 tcp_sack_adjust(struct tcpcb *tp) 480 { 481 struct sackhole *cur = TAILQ_FIRST(&tp->snd_holes); 482 struct sackhole *n = NULL; 483 484 if (TAILQ_EMPTY(&tp->snd_holes)) 485 return; /* No holes */ 486 if (SEQ_GEQ(tp->snd_nxt, tp->rcv_lastsack)) 487 return; /* We're already beyond any SACKed blocks */ 488 489 /* 490 * Two cases for which we want to advance snd_nxt: 491 * i) snd_nxt lies between end of one hole and beginning of another 492 * ii) snd_nxt lies between end of last hole and rcv_lastsack 493 */ 494 while ((n = TAILQ_NEXT(cur, sackhole_q)) != NULL) { 495 if (SEQ_LT(tp->snd_nxt, cur->end)) 496 return; 497 if (SEQ_GEQ(tp->snd_nxt, n->start)) 498 cur = n; 499 else { 500 tp->snd_nxt = n->start; 501 return; 502 } 503 } 504 if (SEQ_LT(tp->snd_nxt, cur->end)) 505 return; 506 tp->snd_nxt = tp->rcv_lastsack; 507 508 return; 509 } 510 511 /* 512 * tcp_sack_numblks: return the number of SACK blocks to send. 513 */ 514 515 int 516 tcp_sack_numblks(const struct tcpcb *tp) 517 { 518 int numblks; 519 520 if (!TCP_SACK_ENABLED(tp)) { 521 return 0; 522 } 523 524 numblks = (((tp->rcv_sack_flags & TCPSACK_HAVED) != 0) ? 1 : 0) + 525 tp->t_segqlen; 526 527 if (numblks == 0) { 528 return 0; 529 } 530 531 if (numblks > TCP_SACK_MAX) { 532 numblks = TCP_SACK_MAX; 533 } 534 535 return numblks; 536 } 537 538 #if defined(DDB) 539 void sack_dump(const struct tcpcb *); 540 541 void 542 sack_dump(const struct tcpcb *tp) 543 { 544 const struct sackhole *cur; 545 546 printf("snd_una=%" PRIu32 ", snd_max=%" PRIu32 "\n", 547 tp->snd_una, tp->snd_max); 548 printf("rcv_lastsack=%" PRIu32 ", snd_fack=%" PRIu32 "\n", 549 tp->rcv_lastsack, tp->snd_fack); 550 printf("numholes=%d\n", tp->snd_numholes); 551 TAILQ_FOREACH(cur, &tp->snd_holes, sackhole_q) { 552 printf("\t%" PRIu32 "-%" PRIu32 ", rxmit=%" PRIu32 "\n", 553 cur->start, cur->end, cur->rxmit); 554 } 555 } 556 #endif /* defined(DDB) */ 557
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