| 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 | |