1 /* 2 * Copyright (c) 2003, 2004 Jeffrey M. Hsu. All rights reserved. 3 * Copyright (c) 2003, 2004 The DragonFly Project. All rights reserved. 4 * 5 * This code is derived from software contributed to The DragonFly Project 6 * by Jeffrey M. Hsu. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. Neither the name of The DragonFly Project nor the names of its 17 * contributors may be used to endorse or promote products derived 18 * from this software without specific, prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 22 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 23 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 24 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 25 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 26 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 27 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 28 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 29 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 30 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * $DragonFly: src/sys/netinet/tcp_sack.c,v 1.8 2008/08/15 21:37:16 nth Exp $ 34 */ 35 36 #include <sys/param.h> 37 #include <sys/systm.h> 38 #include <sys/kernel.h> 39 #include <sys/malloc.h> 40 #include <sys/queue.h> 41 #include <sys/thread.h> 42 #include <sys/types.h> 43 #include <sys/socket.h> 44 #include <sys/socketvar.h> 45 46 #include <net/if.h> 47 48 #include <netinet/in.h> 49 #include <netinet/in_systm.h> 50 #include <netinet/ip.h> 51 #include <netinet/in_var.h> 52 #include <netinet/in_pcb.h> 53 #include <netinet/ip_var.h> 54 #include <netinet/tcp.h> 55 #include <netinet/tcp_seq.h> 56 #include <netinet/tcp_var.h> 57 58 /* 59 * Implemented: 60 * 61 * RFC 2018 62 * RFC 2883 63 * RFC 3517 64 */ 65 66 struct sackblock { 67 tcp_seq sblk_start; 68 tcp_seq sblk_end; 69 TAILQ_ENTRY(sackblock) sblk_list; 70 }; 71 72 #define MAXSAVEDBLOCKS 8 /* per connection limit */ 73 74 static int insert_block(struct scoreboard *scb, 75 const struct raw_sackblock *raw_sb, boolean_t *update); 76 static void update_lostseq(struct scoreboard *scb, tcp_seq snd_una, 77 u_int maxseg, int rxtthresh); 78 79 static MALLOC_DEFINE(M_SACKBLOCK, "sblk", "sackblock struct"); 80 81 /* 82 * Per-tcpcb initialization. 83 */ 84 void 85 tcp_sack_tcpcb_init(struct tcpcb *tp) 86 { 87 struct scoreboard *scb = &tp->scb; 88 89 scb->nblocks = 0; 90 TAILQ_INIT(&scb->sackblocks); 91 scb->lastfound = NULL; 92 } 93 94 /* 95 * Find the SACK block containing or immediately preceding "seq". 96 * The boolean result indicates whether the sequence is actually 97 * contained in the SACK block. 98 */ 99 static boolean_t 100 sack_block_lookup(struct scoreboard *scb, tcp_seq seq, struct sackblock **sb) 101 { 102 struct sackblock *hint = scb->lastfound; 103 struct sackblock *cur, *last, *prev; 104 105 if (TAILQ_EMPTY(&scb->sackblocks)) { 106 *sb = NULL; 107 return FALSE; 108 } 109 110 if (hint == NULL) { 111 /* No hint. Search from start to end. */ 112 cur = TAILQ_FIRST(&scb->sackblocks); 113 last = NULL; 114 prev = TAILQ_LAST(&scb->sackblocks, sackblock_list); 115 } else { 116 if (SEQ_GEQ(seq, hint->sblk_start)) { 117 /* Search from hint to end of list. */ 118 cur = hint; 119 last = NULL; 120 prev = TAILQ_LAST(&scb->sackblocks, sackblock_list); 121 } else { 122 /* Search from front of list to hint. */ 123 cur = TAILQ_FIRST(&scb->sackblocks); 124 last = hint; 125 prev = TAILQ_PREV(hint, sackblock_list, sblk_list); 126 } 127 } 128 129 do { 130 if (SEQ_GT(cur->sblk_end, seq)) { 131 if (SEQ_GEQ(seq, cur->sblk_start)) { 132 *sb = scb->lastfound = cur; 133 return TRUE; 134 } else { 135 *sb = scb->lastfound = 136 TAILQ_PREV(cur, sackblock_list, sblk_list); 137 return FALSE; 138 } 139 } 140 cur = TAILQ_NEXT(cur, sblk_list); 141 } while (cur != last); 142 143 *sb = scb->lastfound = prev; 144 return FALSE; 145 } 146 147 /* 148 * Allocate a SACK block. 149 */ 150 static __inline struct sackblock * 151 alloc_sackblock(struct scoreboard *scb, const struct raw_sackblock *raw_sb) 152 { 153 struct sackblock *sb; 154 155 if (scb->freecache != NULL) { 156 sb = scb->freecache; 157 scb->freecache = NULL; 158 tcpstat.tcps_sacksbfast++; 159 } else { 160 sb = kmalloc(sizeof(struct sackblock), M_SACKBLOCK, M_NOWAIT); 161 if (sb == NULL) { 162 tcpstat.tcps_sacksbfailed++; 163 return NULL; 164 } 165 } 166 sb->sblk_start = raw_sb->rblk_start; 167 sb->sblk_end = raw_sb->rblk_end; 168 return sb; 169 } 170 171 static __inline struct sackblock * 172 alloc_sackblock_limit(struct scoreboard *scb, 173 const struct raw_sackblock *raw_sb) 174 { 175 if (scb->nblocks == MAXSAVEDBLOCKS) { 176 /* 177 * Should try to kick out older blocks XXX JH 178 * May be able to coalesce with existing block. 179 * Or, go other way and free all blocks if we hit 180 * this limit. 181 */ 182 tcpstat.tcps_sacksboverflow++; 183 return NULL; 184 } 185 return alloc_sackblock(scb, raw_sb); 186 } 187 188 /* 189 * Free a SACK block. 190 */ 191 static __inline void 192 free_sackblock(struct scoreboard *scb, struct sackblock *s) 193 { 194 if (scb->freecache == NULL) { 195 /* YYY Maybe use the latest freed block? */ 196 scb->freecache = s; 197 return; 198 } 199 kfree(s, M_SACKBLOCK); 200 } 201 202 /* 203 * Free up SACK blocks for data that's been acked. 204 */ 205 static void 206 tcp_sack_ack_blocks(struct scoreboard *scb, tcp_seq th_ack) 207 { 208 struct sackblock *sb, *nb; 209 210 sb = TAILQ_FIRST(&scb->sackblocks); 211 while (sb && SEQ_LEQ(sb->sblk_end, th_ack)) { 212 nb = TAILQ_NEXT(sb, sblk_list); 213 if (scb->lastfound == sb) 214 scb->lastfound = NULL; 215 TAILQ_REMOVE(&scb->sackblocks, sb, sblk_list); 216 free_sackblock(scb, sb); 217 --scb->nblocks; 218 KASSERT(scb->nblocks >= 0, 219 ("SACK block count underflow: %d < 0", scb->nblocks)); 220 sb = nb; 221 } 222 if (sb && SEQ_GT(th_ack, sb->sblk_start)) 223 sb->sblk_start = th_ack; /* other side reneged? XXX */ 224 } 225 226 /* 227 * Delete and free SACK blocks saved in scoreboard. 228 */ 229 void 230 tcp_sack_cleanup(struct scoreboard *scb) 231 { 232 struct sackblock *sb, *nb; 233 234 TAILQ_FOREACH_MUTABLE(sb, &scb->sackblocks, sblk_list, nb) { 235 free_sackblock(scb, sb); 236 --scb->nblocks; 237 } 238 KASSERT(scb->nblocks == 0, 239 ("SACK block %d count not zero", scb->nblocks)); 240 TAILQ_INIT(&scb->sackblocks); 241 scb->lastfound = NULL; 242 } 243 244 /* 245 * Delete and free SACK blocks saved in scoreboard. 246 * Delete the one slot block cache. 247 */ 248 void 249 tcp_sack_destroy(struct scoreboard *scb) 250 { 251 tcp_sack_cleanup(scb); 252 if (scb->freecache != NULL) { 253 kfree(scb->freecache, M_SACKBLOCK); 254 scb->freecache = NULL; 255 } 256 } 257 258 /* 259 * Cleanup the reported SACK block information 260 */ 261 void 262 tcp_sack_report_cleanup(struct tcpcb *tp) 263 { 264 tp->sack_flags &= 265 ~(TSACK_F_DUPSEG | TSACK_F_ENCLOSESEG | TSACK_F_SACKLEFT); 266 tp->reportblk.rblk_start = tp->reportblk.rblk_end; 267 } 268 269 /* 270 * Returns 0 if not D-SACK block, 271 * 1 if D-SACK, 272 * 2 if duplicate of out-of-order D-SACK block. 273 */ 274 int 275 tcp_sack_ndsack_blocks(struct raw_sackblock *blocks, const int numblocks, 276 tcp_seq snd_una) 277 { 278 if (numblocks == 0) 279 return 0; 280 281 if (SEQ_LT(blocks[0].rblk_start, snd_una)) 282 return 1; 283 284 /* block 0 inside block 1 */ 285 if (numblocks > 1 && 286 SEQ_GEQ(blocks[0].rblk_start, blocks[1].rblk_start) && 287 SEQ_LEQ(blocks[0].rblk_end, blocks[1].rblk_end)) 288 return 2; 289 290 return 0; 291 } 292 293 /* 294 * Update scoreboard on new incoming ACK. 295 */ 296 static void 297 tcp_sack_add_blocks(struct tcpcb *tp, struct tcpopt *to) 298 { 299 const int numblocks = to->to_nsackblocks; 300 struct raw_sackblock *blocks = to->to_sackblocks; 301 struct scoreboard *scb = &tp->scb; 302 int startblock, i; 303 304 if (tcp_sack_ndsack_blocks(blocks, numblocks, tp->snd_una) > 0) 305 startblock = 1; 306 else 307 startblock = 0; 308 309 to->to_flags |= TOF_SACK_REDUNDANT; 310 for (i = startblock; i < numblocks; i++) { 311 struct raw_sackblock *newsackblock = &blocks[i]; 312 boolean_t update; 313 int error; 314 315 /* Guard against ACK reordering */ 316 if (SEQ_LT(newsackblock->rblk_start, tp->snd_una)) 317 continue; 318 319 /* Don't accept bad SACK blocks */ 320 if (SEQ_GT(newsackblock->rblk_end, tp->snd_max)) { 321 tcpstat.tcps_rcvbadsackopt++; 322 break; /* skip all other blocks */ 323 } 324 tcpstat.tcps_sacksbupdate++; 325 326 error = insert_block(scb, newsackblock, &update); 327 if (update) 328 to->to_flags &= ~TOF_SACK_REDUNDANT; 329 if (error) 330 break; 331 } 332 } 333 334 void 335 tcp_sack_update_scoreboard(struct tcpcb *tp, struct tcpopt *to) 336 { 337 struct scoreboard *scb = &tp->scb; 338 int rexmt_high_update = 0; 339 340 tcp_sack_ack_blocks(scb, tp->snd_una); 341 tcp_sack_add_blocks(tp, to); 342 update_lostseq(scb, tp->snd_una, tp->t_maxseg, tp->t_rxtthresh); 343 if (SEQ_LT(tp->rexmt_high, tp->snd_una)) { 344 tp->rexmt_high = tp->snd_una; 345 rexmt_high_update = 1; 346 } 347 if (tp->sack_flags & TSACK_F_SACKRESCUED) { 348 if (SEQ_LT(tp->rexmt_rescue, tp->snd_una)) { 349 tp->sack_flags &= ~TSACK_F_SACKRESCUED; 350 } else if (tcp_aggressive_rescuesack && rexmt_high_update && 351 SEQ_LT(tp->rexmt_rescue, tp->rexmt_high)) { 352 /* Drag RescueRxt along with HighRxt */ 353 tp->rexmt_rescue = tp->rexmt_high; 354 } 355 } 356 } 357 358 /* 359 * Insert SACK block into sender's scoreboard. 360 */ 361 static int 362 insert_block(struct scoreboard *scb, const struct raw_sackblock *raw_sb, 363 boolean_t *update) 364 { 365 struct sackblock *sb, *workingblock; 366 boolean_t overlap_front; 367 368 *update = TRUE; 369 if (TAILQ_EMPTY(&scb->sackblocks)) { 370 struct sackblock *newblock; 371 372 KASSERT(scb->nblocks == 0, ("emply scb w/ blocks")); 373 374 newblock = alloc_sackblock(scb, raw_sb); 375 if (newblock == NULL) 376 return ENOMEM; 377 TAILQ_INSERT_HEAD(&scb->sackblocks, newblock, sblk_list); 378 scb->nblocks = 1; 379 return 0; 380 } 381 382 KASSERT(scb->nblocks > 0, ("insert_block() called w/ no blocks")); 383 KASSERT(scb->nblocks <= MAXSAVEDBLOCKS, 384 ("too many SACK blocks %d", scb->nblocks)); 385 386 overlap_front = sack_block_lookup(scb, raw_sb->rblk_start, &sb); 387 388 if (sb == NULL) { 389 workingblock = alloc_sackblock_limit(scb, raw_sb); 390 if (workingblock == NULL) 391 return ENOMEM; 392 TAILQ_INSERT_HEAD(&scb->sackblocks, workingblock, sblk_list); 393 ++scb->nblocks; 394 } else { 395 if (overlap_front || sb->sblk_end == raw_sb->rblk_start) { 396 /* Extend old block */ 397 workingblock = sb; 398 if (SEQ_GT(raw_sb->rblk_end, sb->sblk_end)) 399 sb->sblk_end = raw_sb->rblk_end; 400 else 401 *update = FALSE; 402 tcpstat.tcps_sacksbreused++; 403 } else { 404 workingblock = alloc_sackblock_limit(scb, raw_sb); 405 if (workingblock == NULL) 406 return ENOMEM; 407 TAILQ_INSERT_AFTER(&scb->sackblocks, sb, workingblock, 408 sblk_list); 409 ++scb->nblocks; 410 } 411 } 412 413 /* Consolidate right-hand side. */ 414 sb = TAILQ_NEXT(workingblock, sblk_list); 415 while (sb != NULL && 416 SEQ_GEQ(workingblock->sblk_end, sb->sblk_end)) { 417 struct sackblock *nextblock; 418 419 nextblock = TAILQ_NEXT(sb, sblk_list); 420 if (scb->lastfound == sb) 421 scb->lastfound = NULL; 422 /* Remove completely overlapped block */ 423 TAILQ_REMOVE(&scb->sackblocks, sb, sblk_list); 424 free_sackblock(scb, sb); 425 --scb->nblocks; 426 KASSERT(scb->nblocks > 0, 427 ("removed overlapped block: %d blocks left", scb->nblocks)); 428 sb = nextblock; 429 } 430 if (sb != NULL && 431 SEQ_GEQ(workingblock->sblk_end, sb->sblk_start)) { 432 /* Extend new block to cover partially overlapped old block. */ 433 workingblock->sblk_end = sb->sblk_end; 434 if (scb->lastfound == sb) 435 scb->lastfound = NULL; 436 TAILQ_REMOVE(&scb->sackblocks, sb, sblk_list); 437 free_sackblock(scb, sb); 438 --scb->nblocks; 439 KASSERT(scb->nblocks > 0, 440 ("removed partial right: %d blocks left", scb->nblocks)); 441 } 442 return 0; 443 } 444 445 #ifdef DEBUG_SACK_BLOCKS 446 static void 447 tcp_sack_dump_blocks(struct scoreboard *scb) 448 { 449 struct sackblock *sb; 450 451 kprintf("%d blocks:", scb->nblocks); 452 TAILQ_FOREACH(sb, &scb->sackblocks, sblk_list) 453 kprintf(" [%u, %u)", sb->sblk_start, sb->sblk_end); 454 kprintf("\n"); 455 } 456 #else 457 static __inline void 458 tcp_sack_dump_blocks(struct scoreboard *scb) 459 { 460 } 461 #endif 462 463 /* 464 * Optimization to quickly determine which packets are lost. 465 */ 466 static void 467 update_lostseq(struct scoreboard *scb, tcp_seq snd_una, u_int maxseg, 468 int rxtthresh) 469 { 470 struct sackblock *sb; 471 int nsackblocks = 0; 472 int bytes_sacked = 0; 473 int rxtthresh_bytes; 474 475 /* 476 * XXX 477 * The RFC3517bis recommends to reduce the byte threshold. 478 * However, it will cause extra spurious retransmit if 479 * segments are reordered. Before certain DupThresh adaptive 480 * algorithm is implemented, we don't reduce the byte 481 * threshold (tcp_rfc3517bis_rxt is off by default). 482 */ 483 if (tcp_do_rfc3517bis && tcp_rfc3517bis_rxt) 484 rxtthresh_bytes = (rxtthresh - 1) * maxseg; 485 else 486 rxtthresh_bytes = rxtthresh * maxseg; 487 488 sb = TAILQ_LAST(&scb->sackblocks, sackblock_list); 489 while (sb != NULL) { 490 ++nsackblocks; 491 bytes_sacked += sb->sblk_end - sb->sblk_start; 492 if (nsackblocks == rxtthresh || 493 bytes_sacked >= rxtthresh_bytes) { 494 scb->lostseq = sb->sblk_start; 495 return; 496 } 497 sb = TAILQ_PREV(sb, sackblock_list, sblk_list); 498 } 499 scb->lostseq = snd_una; 500 } 501 502 /* 503 * Return whether the given sequence number is considered lost. 504 */ 505 boolean_t 506 tcp_sack_islost(struct scoreboard *scb, tcp_seq seqnum) 507 { 508 return SEQ_LT(seqnum, scb->lostseq); 509 } 510 511 /* 512 * True if at least "amount" has been SACKed. Used by Early Retransmit. 513 */ 514 boolean_t 515 tcp_sack_has_sacked(struct scoreboard *scb, u_int amount) 516 { 517 struct sackblock *sb; 518 int bytes_sacked = 0; 519 520 TAILQ_FOREACH(sb, &scb->sackblocks, sblk_list) { 521 bytes_sacked += sb->sblk_end - sb->sblk_start; 522 if (bytes_sacked >= amount) 523 return TRUE; 524 } 525 return FALSE; 526 } 527 528 /* 529 * Number of bytes SACKed below seq. 530 */ 531 int 532 tcp_sack_bytes_below(struct scoreboard *scb, tcp_seq seq) 533 { 534 struct sackblock *sb; 535 int bytes_sacked = 0; 536 537 sb = TAILQ_FIRST(&scb->sackblocks); 538 while (sb && SEQ_GT(seq, sb->sblk_start)) { 539 bytes_sacked += seq_min(seq, sb->sblk_end) - sb->sblk_start; 540 sb = TAILQ_NEXT(sb, sblk_list); 541 } 542 return bytes_sacked; 543 } 544 545 /* 546 * Return estimate of the number of bytes outstanding in the network. 547 */ 548 uint32_t 549 tcp_sack_compute_pipe(struct tcpcb *tp) 550 { 551 struct scoreboard *scb = &tp->scb; 552 struct sackblock *sb; 553 int nlost, nretransmitted; 554 tcp_seq end; 555 556 nlost = tp->snd_max - scb->lostseq; 557 nretransmitted = tp->rexmt_high - tp->snd_una; 558 559 TAILQ_FOREACH(sb, &scb->sackblocks, sblk_list) { 560 if (SEQ_LT(sb->sblk_start, tp->rexmt_high)) { 561 end = seq_min(sb->sblk_end, tp->rexmt_high); 562 nretransmitted -= end - sb->sblk_start; 563 } 564 if (SEQ_GEQ(sb->sblk_start, scb->lostseq)) 565 nlost -= sb->sblk_end - sb->sblk_start; 566 } 567 568 return (nlost + nretransmitted); 569 } 570 571 /* 572 * Return the sequence number and length of the next segment to transmit 573 * when in Fast Recovery. 574 */ 575 boolean_t 576 tcp_sack_nextseg(struct tcpcb *tp, tcp_seq *nextrexmt, uint32_t *plen, 577 boolean_t *rescue) 578 { 579 struct scoreboard *scb = &tp->scb; 580 struct socket *so = tp->t_inpcb->inp_socket; 581 struct sackblock *sb; 582 const struct sackblock *lastblock = 583 TAILQ_LAST(&scb->sackblocks, sackblock_list); 584 tcp_seq torexmt; 585 long len, off; 586 587 /* skip SACKed data */ 588 tcp_sack_skip_sacked(scb, &tp->rexmt_high); 589 590 /* Look for lost data. */ 591 torexmt = tp->rexmt_high; 592 *rescue = FALSE; 593 if (lastblock != NULL) { 594 if (SEQ_LT(torexmt, lastblock->sblk_end) && 595 tcp_sack_islost(scb, torexmt)) { 596 sendunsacked: 597 *nextrexmt = torexmt; 598 /* If the left-hand edge has been SACKed, pull it in. */ 599 if (sack_block_lookup(scb, torexmt + tp->t_maxseg, &sb)) 600 *plen = sb->sblk_start - torexmt; 601 else 602 *plen = tp->t_maxseg; 603 return TRUE; 604 } 605 } 606 607 /* See if unsent data available within send window. */ 608 off = tp->snd_max - tp->snd_una; 609 len = (long) ulmin(so->so_snd.ssb_cc, tp->snd_wnd) - off; 610 if (len > 0) { 611 *nextrexmt = tp->snd_max; /* Send new data. */ 612 *plen = tp->t_maxseg; 613 return TRUE; 614 } 615 616 /* We're less certain this data has been lost. */ 617 if (lastblock != NULL && SEQ_LT(torexmt, lastblock->sblk_end)) 618 goto sendunsacked; 619 620 /* Rescue retransmission */ 621 if (tcp_do_rescuesack || tcp_do_rfc3517bis) { 622 tcpstat.tcps_sackrescue_try++; 623 if (tp->sack_flags & TSACK_F_SACKRESCUED) { 624 if (!tcp_aggressive_rescuesack) 625 return FALSE; 626 627 /* 628 * Aggressive variant of the rescue retransmission. 629 * 630 * The idea of the rescue retransmission is to sustain 631 * the ACK clock thus to avoid timeout retransmission. 632 * 633 * Under some situations, the conservative approach 634 * suggested in the draft 635 * http://tools.ietf.org/html/ 636 * draft-nishida-tcpm-rescue-retransmission-00 637 * could not sustain ACK clock, since it only allows 638 * one rescue retransmission before a cumulative ACK 639 * covers the segement transmitted by rescue 640 * retransmission. 641 * 642 * We try to locate the next unSACKed segment which 643 * follows the previously sent rescue segment. If 644 * there is no such segment, we loop back to the first 645 * unacknowledged segment. 646 */ 647 648 /* 649 * Skip SACKed data, but here we follow 650 * the last transmitted rescue segment. 651 */ 652 torexmt = tp->rexmt_rescue; 653 tcp_sack_skip_sacked(scb, &torexmt); 654 if (torexmt == tp->snd_max) { 655 /* Nothing left to retransmit; restart */ 656 torexmt = tp->snd_una; 657 } 658 } 659 *rescue = TRUE; 660 goto sendunsacked; 661 } else if (tcp_do_smartsack && lastblock == NULL) { 662 tcpstat.tcps_sackrescue_try++; 663 *rescue = TRUE; 664 goto sendunsacked; 665 } 666 667 return FALSE; 668 } 669 670 /* 671 * Return the next sequence number higher than "*prexmt" that has 672 * not been SACKed. 673 */ 674 void 675 tcp_sack_skip_sacked(struct scoreboard *scb, tcp_seq *prexmt) 676 { 677 struct sackblock *sb; 678 679 /* skip SACKed data */ 680 if (sack_block_lookup(scb, *prexmt, &sb)) 681 *prexmt = sb->sblk_end; 682 } 683 684 #ifdef later 685 void 686 tcp_sack_save_scoreboard(struct scoreboard *scb) 687 { 688 struct scoreboard *scb = &tp->scb; 689 690 scb->sackblocks_prev = scb->sackblocks; 691 TAILQ_INIT(&scb->sackblocks); 692 } 693 694 void 695 tcp_sack_revert_scoreboard(struct scoreboard *scb, tcp_seq snd_una, 696 u_int maxseg) 697 { 698 struct sackblock *sb; 699 700 scb->sackblocks = scb->sackblocks_prev; 701 scb->nblocks = 0; 702 TAILQ_FOREACH(sb, &scb->sackblocks, sblk_list) 703 ++scb->nblocks; 704 tcp_sack_ack_blocks(scb, snd_una); 705 scb->lastfound = NULL; 706 } 707 #endif 708 709 #ifdef DEBUG_SACK_HISTORY 710 static void 711 tcp_sack_dump_history(char *msg, struct tcpcb *tp) 712 { 713 int i; 714 static int ndumped; 715 716 /* only need a couple of these to debug most problems */ 717 if (++ndumped > 900) 718 return; 719 720 kprintf("%s:\tnsackhistory %d: ", msg, tp->nsackhistory); 721 for (i = 0; i < tp->nsackhistory; ++i) 722 kprintf("[%u, %u) ", tp->sackhistory[i].rblk_start, 723 tp->sackhistory[i].rblk_end); 724 kprintf("\n"); 725 } 726 #else 727 static __inline void 728 tcp_sack_dump_history(char *msg, struct tcpcb *tp) 729 { 730 } 731 #endif 732 733 /* 734 * Remove old SACK blocks from the SACK history that have already been ACKed. 735 */ 736 static void 737 tcp_sack_ack_history(struct tcpcb *tp) 738 { 739 int i, nblocks, openslot; 740 741 tcp_sack_dump_history("before tcp_sack_ack_history", tp); 742 nblocks = tp->nsackhistory; 743 for (i = openslot = 0; i < nblocks; ++i) { 744 if (SEQ_LEQ(tp->sackhistory[i].rblk_end, tp->rcv_nxt)) { 745 --tp->nsackhistory; 746 continue; 747 } 748 if (SEQ_LT(tp->sackhistory[i].rblk_start, tp->rcv_nxt)) 749 tp->sackhistory[i].rblk_start = tp->rcv_nxt; 750 if (i == openslot) 751 ++openslot; 752 else 753 tp->sackhistory[openslot++] = tp->sackhistory[i]; 754 } 755 tcp_sack_dump_history("after tcp_sack_ack_history", tp); 756 KASSERT(openslot == tp->nsackhistory, 757 ("tcp_sack_ack_history miscounted: %d != %d", 758 openslot, tp->nsackhistory)); 759 } 760 761 /* 762 * Add or merge newblock into reported history. 763 * Also remove or update SACK blocks that will be acked. 764 */ 765 static void 766 tcp_sack_update_reported_history(struct tcpcb *tp, tcp_seq start, tcp_seq end) 767 { 768 struct raw_sackblock copy[MAX_SACK_REPORT_BLOCKS]; 769 int i, cindex; 770 771 tcp_sack_dump_history("before tcp_sack_update_reported_history", tp); 772 /* 773 * Six cases: 774 * 0) no overlap 775 * 1) newblock == oldblock 776 * 2) oldblock contains newblock 777 * 3) newblock contains oldblock 778 * 4) tail of oldblock overlaps or abuts start of newblock 779 * 5) tail of newblock overlaps or abuts head of oldblock 780 */ 781 for (i = cindex = 0; i < tp->nsackhistory; ++i) { 782 struct raw_sackblock *oldblock = &tp->sackhistory[i]; 783 tcp_seq old_start = oldblock->rblk_start; 784 tcp_seq old_end = oldblock->rblk_end; 785 786 if (SEQ_LT(end, old_start) || SEQ_GT(start, old_end)) { 787 /* Case 0: no overlap. Copy old block. */ 788 copy[cindex++] = *oldblock; 789 continue; 790 } 791 792 if (SEQ_GEQ(start, old_start) && SEQ_LEQ(end, old_end)) { 793 /* Cases 1 & 2. Move block to front of history. */ 794 int j; 795 796 start = old_start; 797 end = old_end; 798 /* no need to check rest of blocks */ 799 for (j = i + 1; j < tp->nsackhistory; ++j) 800 copy[cindex++] = tp->sackhistory[j]; 801 break; 802 } 803 804 if (SEQ_GEQ(old_end, start) && SEQ_LT(old_start, start)) { 805 /* Case 4: extend start of new block. */ 806 start = old_start; 807 } else if (SEQ_GEQ(end, old_start) && SEQ_GT(old_end, end)) { 808 /* Case 5: extend end of new block */ 809 end = old_end; 810 } else { 811 /* Case 3. Delete old block by not copying it. */ 812 KASSERT(SEQ_LEQ(start, old_start) && 813 SEQ_GEQ(end, old_end), 814 ("bad logic: old [%u, %u), new [%u, %u)", 815 old_start, old_end, start, end)); 816 } 817 } 818 819 /* insert new block */ 820 tp->sackhistory[0].rblk_start = start; 821 tp->sackhistory[0].rblk_end = end; 822 cindex = min(cindex, MAX_SACK_REPORT_BLOCKS - 1); 823 for (i = 0; i < cindex; ++i) 824 tp->sackhistory[i + 1] = copy[i]; 825 tp->nsackhistory = cindex + 1; 826 tcp_sack_dump_history("after tcp_sack_update_reported_history", tp); 827 } 828 829 /* 830 * Fill in SACK report to return to data sender. 831 */ 832 void 833 tcp_sack_fill_report(struct tcpcb *tp, u_char *opt, u_int *plen) 834 { 835 u_int optlen = *plen; 836 uint32_t *lp = (uint32_t *)(opt + optlen); 837 uint32_t *olp; 838 tcp_seq hstart = tp->rcv_nxt, hend; 839 int nblocks; 840 841 KASSERT(TCP_MAXOLEN - optlen >= 842 TCPOLEN_SACK_ALIGNED + TCPOLEN_SACK_BLOCK, 843 ("no room for SACK header and one block: optlen %d", optlen)); 844 845 if (tp->sack_flags & TSACK_F_DUPSEG) 846 tcpstat.tcps_snddsackopt++; 847 else 848 tcpstat.tcps_sndsackopt++; 849 850 olp = lp++; 851 optlen += TCPOLEN_SACK_ALIGNED; 852 853 tcp_sack_ack_history(tp); 854 if (tp->reportblk.rblk_start != tp->reportblk.rblk_end) { 855 *lp++ = htonl(tp->reportblk.rblk_start); 856 *lp++ = htonl(tp->reportblk.rblk_end); 857 optlen += TCPOLEN_SACK_BLOCK; 858 hstart = tp->reportblk.rblk_start; 859 hend = tp->reportblk.rblk_end; 860 if (tp->sack_flags & TSACK_F_ENCLOSESEG) { 861 KASSERT(TCP_MAXOLEN - optlen >= TCPOLEN_SACK_BLOCK, 862 ("no room for enclosing SACK block: oplen %d", 863 optlen)); 864 *lp++ = htonl(tp->encloseblk.rblk_start); 865 *lp++ = htonl(tp->encloseblk.rblk_end); 866 optlen += TCPOLEN_SACK_BLOCK; 867 hstart = tp->encloseblk.rblk_start; 868 hend = tp->encloseblk.rblk_end; 869 } 870 if (SEQ_GT(hstart, tp->rcv_nxt)) 871 tcp_sack_update_reported_history(tp, hstart, hend); 872 } 873 if (tcp_do_smartsack && (tp->sack_flags & TSACK_F_SACKLEFT)) { 874 /* Fill in from left! Walk re-assembly queue. */ 875 struct tseg_qent *q; 876 877 q = LIST_FIRST(&tp->t_segq); 878 while (q != NULL && 879 TCP_MAXOLEN - optlen >= TCPOLEN_SACK_BLOCK) { 880 *lp++ = htonl(q->tqe_th->th_seq); 881 *lp++ = htonl(TCP_SACK_BLKEND( 882 q->tqe_th->th_seq + q->tqe_len, 883 q->tqe_th->th_flags)); 884 optlen += TCPOLEN_SACK_BLOCK; 885 q = LIST_NEXT(q, tqe_q); 886 } 887 } else { 888 int n = 0; 889 890 /* Fill in SACK blocks from right side. */ 891 while (n < tp->nsackhistory && 892 TCP_MAXOLEN - optlen >= TCPOLEN_SACK_BLOCK) { 893 if (tp->sackhistory[n].rblk_start != hstart) { 894 *lp++ = htonl(tp->sackhistory[n].rblk_start); 895 *lp++ = htonl(tp->sackhistory[n].rblk_end); 896 optlen += TCPOLEN_SACK_BLOCK; 897 } 898 ++n; 899 } 900 } 901 tp->reportblk.rblk_start = tp->reportblk.rblk_end; 902 tp->sack_flags &= 903 ~(TSACK_F_DUPSEG | TSACK_F_ENCLOSESEG | TSACK_F_SACKLEFT); 904 nblocks = (lp - olp - 1) / 2; 905 *olp = htonl(TCPOPT_SACK_ALIGNED | 906 (TCPOLEN_SACK + nblocks * TCPOLEN_SACK_BLOCK)); 907 *plen = optlen; 908 } 909