1 /* $NetBSD: tcp_sack.c,v 1.36 2018/05/18 18:58:51 maxv 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 1.36 2018/05/18 18:58:51 maxv 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 #include <netinet/ip6.h> 139 #include <netinet6/ip6_var.h> 140 #include <netinet6/in6_pcb.h> 141 #include <netinet6/ip6_var.h> 142 #include <netinet6/in6_var.h> 143 #include <netinet/icmp6.h> 144 #endif 145 146 #ifndef INET6 147 #include <netinet/ip6.h> 148 #endif 149 150 #include <netinet/tcp.h> 151 #include <netinet/tcp_fsm.h> 152 #include <netinet/tcp_seq.h> 153 #include <netinet/tcp_timer.h> 154 #include <netinet/tcp_var.h> 155 #include <netinet/tcp_debug.h> 156 157 /* SACK block pool. */ 158 static struct pool sackhole_pool; 159 160 void 161 tcp_sack_init(void) 162 { 163 164 pool_init(&sackhole_pool, sizeof(struct sackhole), 0, 0, 0, 165 "sackholepl", NULL, IPL_SOFTNET); 166 } 167 168 static struct sackhole * 169 sack_allochole(struct tcpcb *tp) 170 { 171 struct sackhole *hole; 172 173 if (tp->snd_numholes >= tcp_sack_tp_maxholes || 174 tcp_sack_globalholes >= tcp_sack_globalmaxholes) { 175 return NULL; 176 } 177 hole = pool_get(&sackhole_pool, PR_NOWAIT); 178 if (hole == NULL) { 179 return NULL; 180 } 181 tp->snd_numholes++; 182 tcp_sack_globalholes++; 183 184 return hole; 185 } 186 187 static struct sackhole * 188 sack_inserthole(struct tcpcb *tp, tcp_seq start, tcp_seq end, 189 struct sackhole *prev) 190 { 191 struct sackhole *hole; 192 193 hole = sack_allochole(tp); 194 if (hole == NULL) { 195 return NULL; 196 } 197 hole->start = hole->rxmit = start; 198 hole->end = end; 199 if (prev != NULL) { 200 TAILQ_INSERT_AFTER(&tp->snd_holes, prev, hole, sackhole_q); 201 } else { 202 TAILQ_INSERT_TAIL(&tp->snd_holes, hole, sackhole_q); 203 } 204 return hole; 205 } 206 207 static struct sackhole * 208 sack_removehole(struct tcpcb *tp, struct sackhole *hole) 209 { 210 struct sackhole *next; 211 212 next = TAILQ_NEXT(hole, sackhole_q); 213 tp->snd_numholes--; 214 tcp_sack_globalholes--; 215 TAILQ_REMOVE(&tp->snd_holes, hole, sackhole_q); 216 pool_put(&sackhole_pool, hole); 217 218 return next; 219 } 220 221 /* 222 * tcp_new_dsack: record the reception of a duplicated segment. 223 */ 224 225 void 226 tcp_new_dsack(struct tcpcb *tp, tcp_seq seq, u_int32_t len) 227 { 228 229 if (TCP_SACK_ENABLED(tp)) { 230 tp->rcv_dsack_block.left = seq; 231 tp->rcv_dsack_block.right = seq + len; 232 tp->rcv_sack_flags |= TCPSACK_HAVED; 233 } 234 } 235 236 /* 237 * tcp_sack_option: parse the given SACK option and update the scoreboard. 238 */ 239 240 void 241 tcp_sack_option(struct tcpcb *tp, const struct tcphdr *th, const u_char *cp, 242 int optlen) 243 { 244 struct sackblk 245 t_sack_block[(MAX_TCPOPTLEN - 2) / (sizeof(u_int32_t) * 2)]; 246 struct sackblk *sack = NULL; 247 struct sackhole *cur = NULL; 248 struct sackhole *tmp = NULL; 249 const char *lp = cp + 2; 250 int i, j, num_sack_blks; 251 tcp_seq left, right, acked; 252 253 /* 254 * If we aren't processing SACK responses, this is not an ACK 255 * or the peer sends us a sack option with invalid length, don't 256 * update the scoreboard. 257 */ 258 if (!TCP_SACK_ENABLED(tp) || ((th->th_flags & TH_ACK) == 0) || 259 (optlen % 8 != 2 || optlen < 10)) { 260 return; 261 } 262 263 /* 264 * If we don't want any SACK holes to be allocated, just return. 265 */ 266 if (tcp_sack_globalmaxholes == 0 || tcp_sack_tp_maxholes == 0) { 267 return; 268 } 269 270 /* If the ACK is outside [snd_una, snd_max], ignore the SACK options. */ 271 if (SEQ_LT(th->th_ack, tp->snd_una) || SEQ_GT(th->th_ack, tp->snd_max)) 272 return; 273 274 /* 275 * Extract SACK blocks. 276 * 277 * Note that t_sack_block is sorted so that we only need to do 278 * one pass over the sequence number space. (SACK "fast-path") 279 */ 280 num_sack_blks = optlen / 8; 281 acked = (SEQ_GT(th->th_ack, tp->snd_una)) ? th->th_ack : tp->snd_una; 282 for (i = 0; i < num_sack_blks; i++, lp += sizeof(uint32_t) * 2) { 283 memcpy(&left, lp, sizeof(uint32_t)); 284 memcpy(&right, lp + sizeof(uint32_t), sizeof(uint32_t)); 285 left = ntohl(left); 286 right = ntohl(right); 287 288 if (SEQ_LEQ(right, acked) || SEQ_GT(right, tp->snd_max) || 289 SEQ_GEQ(left, right)) { 290 /* SACK entry that's old, or invalid. */ 291 i--; 292 num_sack_blks--; 293 continue; 294 } 295 296 /* Insertion sort. */ 297 for (j = i; (j > 0) && SEQ_LT(left, t_sack_block[j - 1].left); 298 j--) { 299 t_sack_block[j].left = t_sack_block[j - 1].left; 300 t_sack_block[j].right = t_sack_block[j - 1].right; 301 } 302 t_sack_block[j].left = left; 303 t_sack_block[j].right = right; 304 } 305 306 /* Update the scoreboard. */ 307 cur = TAILQ_FIRST(&tp->snd_holes); 308 for (i = 0; i < num_sack_blks; i++) { 309 sack = &t_sack_block[i]; 310 /* 311 * FACK TCP. Update snd_fack so we can enter Fast 312 * Recovery early. 313 */ 314 if (SEQ_GEQ(sack->right, tp->snd_fack)) 315 tp->snd_fack = sack->right; 316 317 if (TAILQ_EMPTY(&tp->snd_holes)) { 318 /* First hole. */ 319 cur = sack_inserthole(tp, th->th_ack, sack->left, NULL); 320 if (cur == NULL) { 321 /* ENOBUFS, bail out*/ 322 return; 323 } 324 tp->rcv_lastsack = sack->right; 325 continue; /* With next sack block */ 326 } 327 328 /* Go through the list of holes. */ 329 while (cur) { 330 if (SEQ_LEQ(sack->right, cur->start)) 331 /* SACKs data before the current hole */ 332 break; /* No use going through more holes */ 333 334 if (SEQ_GEQ(sack->left, cur->end)) { 335 /* SACKs data beyond the current hole */ 336 cur = TAILQ_NEXT(cur, sackhole_q); 337 continue; 338 } 339 340 if (SEQ_LEQ(sack->left, cur->start)) { 341 /* Data acks at least the beginning of hole */ 342 if (SEQ_GEQ(sack->right, cur->end)) { 343 /* Acks entire hole, so delete hole */ 344 cur = sack_removehole(tp, cur); 345 break; 346 } 347 348 /* Otherwise, move start of hole forward */ 349 cur->start = sack->right; 350 cur->rxmit = SEQ_MAX(cur->rxmit, cur->start); 351 break; 352 } 353 354 if (SEQ_GEQ(sack->right, cur->end)) { 355 /* Move end of hole backward. */ 356 cur->end = sack->left; 357 cur->rxmit = SEQ_MIN(cur->rxmit, cur->end); 358 cur = TAILQ_NEXT(cur, sackhole_q); 359 break; 360 } 361 362 if (SEQ_LT(cur->start, sack->left) && 363 SEQ_GT(cur->end, sack->right)) { 364 /* 365 * ACKs some data in middle of a hole; need to 366 * split current hole 367 */ 368 tmp = sack_inserthole(tp, sack->right, cur->end, 369 cur); 370 if (tmp == NULL) { 371 return; 372 } 373 tmp->rxmit = SEQ_MAX(cur->rxmit, tmp->start); 374 cur->end = sack->left; 375 cur->rxmit = SEQ_MIN(cur->rxmit, cur->end); 376 cur = tmp; 377 break; 378 } 379 } 380 381 /* At this point, we have reached the tail of the list. */ 382 if (SEQ_LT(tp->rcv_lastsack, sack->left)) { 383 /* 384 * Need to append new hole at end. 385 */ 386 cur = sack_inserthole(tp, tp->rcv_lastsack, sack->left, 387 NULL); 388 if (cur == NULL) { 389 return; 390 } 391 } 392 if (SEQ_LT(tp->rcv_lastsack, sack->right)) { 393 tp->rcv_lastsack = sack->right; 394 } 395 } 396 } 397 398 /* 399 * tcp_del_sackholes: remove holes covered by a cumulative ACK. 400 */ 401 402 void 403 tcp_del_sackholes(struct tcpcb *tp, const struct tcphdr *th) 404 { 405 /* Max because this could be an older ack that just arrived. */ 406 tcp_seq lastack = SEQ_GT(th->th_ack, tp->snd_una) ? 407 th->th_ack : tp->snd_una; 408 struct sackhole *cur = TAILQ_FIRST(&tp->snd_holes); 409 410 while (cur) { 411 if (SEQ_LEQ(cur->end, lastack)) { 412 cur = sack_removehole(tp, cur); 413 } else if (SEQ_LT(cur->start, lastack)) { 414 cur->start = lastack; 415 if (SEQ_LT(cur->rxmit, cur->start)) 416 cur->rxmit = cur->start; 417 break; 418 } else 419 break; 420 } 421 } 422 423 /* 424 * tcp_free_sackholes: clear the scoreboard. 425 */ 426 427 void 428 tcp_free_sackholes(struct tcpcb *tp) 429 { 430 struct sackhole *sack; 431 432 /* Free up the SACK hole list. */ 433 while ((sack = TAILQ_FIRST(&tp->snd_holes)) != NULL) { 434 sack_removehole(tp, sack); 435 } 436 KASSERT(tp->snd_numholes == 0); 437 } 438 439 /* 440 * Returns pointer to a sackhole if there are any pending retransmissions; 441 * NULL otherwise. 442 */ 443 struct sackhole * 444 tcp_sack_output(struct tcpcb *tp, int *sack_bytes_rexmt) 445 { 446 struct sackhole *cur = NULL; 447 448 if (!TCP_SACK_ENABLED(tp)) 449 return (NULL); 450 451 *sack_bytes_rexmt = 0; 452 TAILQ_FOREACH(cur, &tp->snd_holes, sackhole_q) { 453 if (SEQ_LT(cur->rxmit, cur->end)) { 454 if (SEQ_LT(cur->rxmit, tp->snd_una)) { 455 /* old SACK hole */ 456 continue; 457 } 458 *sack_bytes_rexmt += (cur->rxmit - cur->start); 459 break; 460 } 461 *sack_bytes_rexmt += (cur->rxmit - cur->start); 462 } 463 464 return (cur); 465 } 466 467 /* 468 * After a timeout, the SACK list may be rebuilt. This SACK information 469 * should be used to avoid retransmitting SACKed data. This function 470 * traverses the SACK list to see if snd_nxt should be moved forward. 471 */ 472 void 473 tcp_sack_adjust(struct tcpcb *tp) 474 { 475 struct sackhole *cur = TAILQ_FIRST(&tp->snd_holes); 476 struct sackhole *n = NULL; 477 478 if (TAILQ_EMPTY(&tp->snd_holes)) 479 return; /* No holes */ 480 if (SEQ_GEQ(tp->snd_nxt, tp->rcv_lastsack)) 481 return; /* We're already beyond any SACKed blocks */ 482 483 /* 484 * Two cases for which we want to advance snd_nxt: 485 * i) snd_nxt lies between end of one hole and beginning of another 486 * ii) snd_nxt lies between end of last hole and rcv_lastsack 487 */ 488 while ((n = TAILQ_NEXT(cur, sackhole_q)) != NULL) { 489 if (SEQ_LT(tp->snd_nxt, cur->end)) 490 return; 491 if (SEQ_GEQ(tp->snd_nxt, n->start)) 492 cur = n; 493 else { 494 tp->snd_nxt = n->start; 495 return; 496 } 497 } 498 if (SEQ_LT(tp->snd_nxt, cur->end)) 499 return; 500 tp->snd_nxt = tp->rcv_lastsack; 501 502 return; 503 } 504 505 /* 506 * tcp_sack_numblks: return the number of SACK blocks to send. 507 */ 508 509 int 510 tcp_sack_numblks(const struct tcpcb *tp) 511 { 512 int numblks; 513 514 if (!TCP_SACK_ENABLED(tp)) { 515 return 0; 516 } 517 518 numblks = (((tp->rcv_sack_flags & TCPSACK_HAVED) != 0) ? 1 : 0) + 519 tp->t_segqlen; 520 521 if (numblks == 0) { 522 return 0; 523 } 524 525 if (numblks > TCP_SACK_MAX) { 526 numblks = TCP_SACK_MAX; 527 } 528 529 return numblks; 530 } 531 532 #if defined(DDB) 533 void sack_dump(const struct tcpcb *); 534 535 void 536 sack_dump(const struct tcpcb *tp) 537 { 538 const struct sackhole *cur; 539 540 printf("snd_una=%" PRIu32 ", snd_max=%" PRIu32 "\n", 541 tp->snd_una, tp->snd_max); 542 printf("rcv_lastsack=%" PRIu32 ", snd_fack=%" PRIu32 "\n", 543 tp->rcv_lastsack, tp->snd_fack); 544 printf("numholes=%d\n", tp->snd_numholes); 545 TAILQ_FOREACH(cur, &tp->snd_holes, sackhole_q) { 546 printf("\t%" PRIu32 "-%" PRIu32 ", rxmit=%" PRIu32 "\n", 547 cur->start, cur->end, cur->rxmit); 548 } 549 } 550 #endif /* defined(DDB) */ 551
Indexes created Sun Sep 21 15:09:59 GMT 2025