Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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sys/netinet/tcp_reass.c
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1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the University nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 * 31 * @(#)tcp_input.c 8.12 (Berkeley) 5/24/95 32 */ 33 34 #include <sys/cdefs.h> 35 __FBSDID("$FreeBSD$"); 36 37 #include "opt_inet.h" 38 #include "opt_inet6.h" 39 #include "opt_tcpdebug.h" 40 41 /* For debugging we want counters and BB logging */ 42 /* #define TCP_REASS_COUNTERS 1 */ 43 /* #define TCP_REASS_LOGGING 1 */ 44 45 #include <sys/param.h> 46 #include <sys/kernel.h> 47 #include <sys/eventhandler.h> 48 #include <sys/malloc.h> 49 #include <sys/mbuf.h> 50 #include <sys/socket.h> 51 #include <sys/socketvar.h> 52 #include <sys/sysctl.h> 53 #include <sys/syslog.h> 54 #include <sys/systm.h> 55 56 #include <vm/uma.h> 57 58 #include <net/if.h> 59 #include <net/if_var.h> 60 #include <net/route.h> 61 #include <net/vnet.h> 62 63 #include <netinet/in.h> 64 #include <netinet/in_pcb.h> 65 #include <netinet/in_systm.h> 66 #include <netinet/in_var.h> 67 #include <netinet/ip.h> 68 #include <netinet/ip_var.h> 69 #include <netinet/ip_options.h> 70 #include <netinet/ip6.h> 71 #include <netinet6/in6_pcb.h> 72 #include <netinet6/ip6_var.h> 73 #include <netinet6/nd6.h> 74 #include <netinet/tcp.h> 75 #include <netinet/tcp_fsm.h> 76 #include <netinet/tcp_seq.h> 77 #include <netinet/tcp_timer.h> 78 #include <netinet/tcp_var.h> 79 #ifdef TCP_REASS_LOGGING 80 #include <netinet/tcp_log_buf.h> 81 #include <netinet/tcp_hpts.h> 82 #endif 83 #include <netinet6/tcp6_var.h> 84 #include <netinet/tcpip.h> 85 #ifdef TCPDEBUG 86 #include <netinet/tcp_debug.h> 87 #endif /* TCPDEBUG */ 88 89 #define TCP_R_LOG_ADD 1 90 #define TCP_R_LOG_LIMIT_REACHED 2 91 #define TCP_R_LOG_APPEND 3 92 #define TCP_R_LOG_PREPEND 4 93 #define TCP_R_LOG_REPLACE 5 94 #define TCP_R_LOG_MERGE_INTO 6 95 #define TCP_R_LOG_NEW_ENTRY 7 96 #define TCP_R_LOG_READ 8 97 #define TCP_R_LOG_ZERO 9 98 #define TCP_R_LOG_DUMP 10 99 #define TCP_R_LOG_TRIM 11 100 101 static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass, CTLFLAG_RW, 0, 102 "TCP Segment Reassembly Queue"); 103 104 static SYSCTL_NODE(_net_inet_tcp_reass, OID_AUTO, stats, CTLFLAG_RW, 0, 105 "TCP Segment Reassembly stats"); 106 107 108 static int tcp_reass_maxseg = 0; 109 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RDTUN, 110 &tcp_reass_maxseg, 0, 111 "Global maximum number of TCP Segments in Reassembly Queue"); 112 113 static uma_zone_t tcp_reass_zone; 114 SYSCTL_UMA_CUR(_net_inet_tcp_reass, OID_AUTO, cursegments, 0, 115 &tcp_reass_zone, 116 "Global number of TCP Segments currently in Reassembly Queue"); 117 118 static u_int tcp_reass_maxqueuelen = 100; 119 SYSCTL_UINT(_net_inet_tcp_reass, OID_AUTO, maxqueuelen, CTLFLAG_RWTUN, 120 &tcp_reass_maxqueuelen, 0, 121 "Maximum number of TCP Segments per Reassembly Queue"); 122 123 static int tcp_new_limits = 0; 124 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, new_limit, CTLFLAG_RWTUN, 125 &tcp_new_limits, 0, 126 "Do we use the new limit method we are discussing?"); 127 128 static u_int tcp_reass_queue_guard = 16; 129 SYSCTL_UINT(_net_inet_tcp_reass, OID_AUTO, queueguard, CTLFLAG_RWTUN, 130 &tcp_reass_queue_guard, 16, 131 "Number of TCP Segments in Reassembly Queue where we flip over to guard mode"); 132 133 #ifdef TCP_REASS_COUNTERS 134 135 counter_u64_t reass_entry; 136 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, entry, CTLFLAG_RD, 137 &reass_entry, "A segment entered reassembly "); 138 139 counter_u64_t reass_path1; 140 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path1, CTLFLAG_RD, 141 &reass_path1, "Took path 1"); 142 143 counter_u64_t reass_path2; 144 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path2, CTLFLAG_RD, 145 &reass_path2, "Took path 2"); 146 147 counter_u64_t reass_path3; 148 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path3, CTLFLAG_RD, 149 &reass_path3, "Took path 3"); 150 151 counter_u64_t reass_path4; 152 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path4, CTLFLAG_RD, 153 &reass_path4, "Took path 4"); 154 155 counter_u64_t reass_path5; 156 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path5, CTLFLAG_RD, 157 &reass_path5, "Took path 5"); 158 159 counter_u64_t reass_path6; 160 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path6, CTLFLAG_RD, 161 &reass_path6, "Took path 6"); 162 163 counter_u64_t reass_path7; 164 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, path7, CTLFLAG_RD, 165 &reass_path7, "Took path 7"); 166 167 counter_u64_t reass_fullwalk; 168 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, fullwalk, CTLFLAG_RD, 169 &reass_fullwalk, "Took a full walk "); 170 171 counter_u64_t reass_nospace; 172 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, nospace, CTLFLAG_RD, 173 &reass_nospace, "Had no mbuf capacity "); 174 175 counter_u64_t merge_fwd; 176 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, merge_fwd, CTLFLAG_RD, 177 &merge_fwd, "Ran merge fwd"); 178 179 counter_u64_t merge_into; 180 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, merge_into, CTLFLAG_RD, 181 &merge_into, "Ran merge into"); 182 183 counter_u64_t tcp_zero_input; 184 SYSCTL_COUNTER_U64(_net_inet_tcp_reass_stats, OID_AUTO, zero_input, CTLFLAG_RD, 185 &tcp_zero_input, "The reassembly buffer saw a zero len segment etc"); 186 187 #endif 188 189 /* Initialize TCP reassembly queue */ 190 static void 191 tcp_reass_zone_change(void *tag) 192 { 193 194 /* Set the zone limit and read back the effective value. */ 195 tcp_reass_maxseg = nmbclusters / 16; 196 tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone, 197 tcp_reass_maxseg); 198 } 199 200 #ifdef TCP_REASS_LOGGING 201 202 static void 203 tcp_log_reassm(struct tcpcb *tp, struct tseg_qent *q, struct tseg_qent *p, 204 tcp_seq seq, int len, uint8_t action, int instance) 205 { 206 uint32_t cts; 207 struct timeval tv; 208 209 if (tp->t_logstate != TCP_LOG_STATE_OFF) { 210 union tcp_log_stackspecific log; 211 212 memset(&log, 0, sizeof(log)); 213 cts = tcp_get_usecs(&tv); 214 log.u_bbr.flex1 = seq; 215 log.u_bbr.cur_del_rate = (uint64_t)q; 216 log.u_bbr.delRate = (uint64_t)p; 217 if (q != NULL) { 218 log.u_bbr.flex2 = q->tqe_start; 219 log.u_bbr.flex3 = q->tqe_len; 220 log.u_bbr.flex4 = q->tqe_mbuf_cnt; 221 log.u_bbr.hptsi_gain = q->tqe_flags; 222 } 223 if (p != NULL) { 224 log.u_bbr.flex5 = p->tqe_start; 225 log.u_bbr.pkts_out = p->tqe_len; 226 log.u_bbr.epoch = p->tqe_mbuf_cnt; 227 log.u_bbr.cwnd_gain = p->tqe_flags; 228 } 229 log.u_bbr.flex6 = tp->t_segqmbuflen; 230 log.u_bbr.flex7 = instance; 231 log.u_bbr.flex8 = action; 232 log.u_bbr.timeStamp = cts; 233 TCP_LOG_EVENTP(tp, NULL, 234 &tp->t_inpcb->inp_socket->so_rcv, 235 &tp->t_inpcb->inp_socket->so_snd, 236 TCP_LOG_REASS, 0, 237 len, &log, false, &tv); 238 } 239 } 240 241 static void 242 tcp_reass_log_dump(struct tcpcb *tp) 243 { 244 struct tseg_qent *q; 245 246 if (tp->t_logstate != TCP_LOG_STATE_OFF) { 247 TAILQ_FOREACH(q, &tp->t_segq, tqe_q) { 248 tcp_log_reassm(tp, q, NULL, q->tqe_start, q->tqe_len, TCP_R_LOG_DUMP, 0); 249 } 250 }; 251 } 252 253 static void 254 tcp_reass_log_new_in(struct tcpcb *tp, tcp_seq seq, int len, struct mbuf *m, 255 int logval, struct tseg_qent *q) 256 { 257 int cnt; 258 struct mbuf *t; 259 260 cnt = 0; 261 t = m; 262 while (t) { 263 cnt += t->m_len; 264 t = t->m_next; 265 } 266 tcp_log_reassm(tp, q, NULL, seq, len, logval, cnt); 267 } 268 269 #endif 270 271 void 272 tcp_reass_global_init(void) 273 { 274 275 tcp_reass_maxseg = nmbclusters / 16; 276 TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments", 277 &tcp_reass_maxseg); 278 tcp_reass_zone = uma_zcreate("tcpreass", sizeof (struct tseg_qent), 279 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 280 /* Set the zone limit and read back the effective value. */ 281 tcp_reass_maxseg = uma_zone_set_max(tcp_reass_zone, 282 tcp_reass_maxseg); 283 #ifdef TCP_REASS_COUNTERS 284 reass_path1 = counter_u64_alloc(M_WAITOK); 285 reass_path2 = counter_u64_alloc(M_WAITOK); 286 reass_path3 = counter_u64_alloc(M_WAITOK); 287 reass_path4 = counter_u64_alloc(M_WAITOK); 288 reass_path5 = counter_u64_alloc(M_WAITOK); 289 reass_path6 = counter_u64_alloc(M_WAITOK); 290 reass_path7 = counter_u64_alloc(M_WAITOK); 291 reass_fullwalk = counter_u64_alloc(M_WAITOK); 292 reass_nospace = counter_u64_alloc(M_WAITOK); 293 reass_entry = counter_u64_alloc(M_WAITOK); 294 merge_fwd = counter_u64_alloc(M_WAITOK); 295 merge_into = counter_u64_alloc(M_WAITOK); 296 tcp_zero_input = counter_u64_alloc(M_WAITOK); 297 #endif 298 EVENTHANDLER_REGISTER(nmbclusters_change, 299 tcp_reass_zone_change, NULL, EVENTHANDLER_PRI_ANY); 300 301 } 302 303 void 304 tcp_reass_flush(struct tcpcb *tp) 305 { 306 struct tseg_qent *qe; 307 308 INP_WLOCK_ASSERT(tp->t_inpcb); 309 310 while ((qe = TAILQ_FIRST(&tp->t_segq)) != NULL) { 311 TAILQ_REMOVE(&tp->t_segq, qe, tqe_q); 312 m_freem(qe->tqe_m); 313 uma_zfree(tcp_reass_zone, qe); 314 tp->t_segqlen--; 315 } 316 tp->t_segqmbuflen = 0; 317 KASSERT((tp->t_segqlen == 0), 318 ("TCP reass queue %p segment count is %d instead of 0 after flush.", 319 tp, tp->t_segqlen)); 320 } 321 322 static void 323 tcp_reass_append(struct tcpcb *tp, struct tseg_qent *last, 324 struct mbuf *m, struct tcphdr *th, int tlen, 325 struct mbuf *mlast, int lenofoh) 326 { 327 328 #ifdef TCP_REASS_LOGGING 329 tcp_log_reassm(tp, last, NULL, th->th_seq, tlen, TCP_R_LOG_APPEND, 0); 330 #endif 331 last->tqe_len += tlen; 332 last->tqe_m->m_pkthdr.len += tlen; 333 /* Preserve the FIN bit if its there */ 334 last->tqe_flags |= (th->th_flags & TH_FIN); 335 last->tqe_last->m_next = m; 336 last->tqe_last = mlast; 337 last->tqe_mbuf_cnt += lenofoh; 338 tp->t_rcvoopack++; 339 TCPSTAT_INC(tcps_rcvoopack); 340 TCPSTAT_ADD(tcps_rcvoobyte, tlen); 341 #ifdef TCP_REASS_LOGGING 342 tcp_reass_log_new_in(tp, last->tqe_start, lenofoh, last->tqe_m, 343 TCP_R_LOG_APPEND, 344 last); 345 #endif 346 } 347 348 static void 349 tcp_reass_prepend(struct tcpcb *tp, struct tseg_qent *first, struct mbuf *m, struct tcphdr *th, 350 int tlen, struct mbuf *mlast, int lenofoh) 351 { 352 int i; 353 354 #ifdef TCP_REASS_LOGGING 355 tcp_log_reassm(tp, first, NULL, th->th_seq, tlen, TCP_R_LOG_PREPEND, 0); 356 #endif 357 if (SEQ_GT((th->th_seq + tlen), first->tqe_start)) { 358 /* The new data overlaps into the old */ 359 i = (th->th_seq + tlen) - first->tqe_start; 360 #ifdef TCP_REASS_LOGGING 361 tcp_log_reassm(tp, first, NULL, 0, i, TCP_R_LOG_TRIM, 1); 362 #endif 363 m_adj(first->tqe_m, i); 364 first->tqe_len -= i; 365 first->tqe_start += i; 366 } 367 /* Ok now setup our chain to point to the old first */ 368 mlast->m_next = first->tqe_m; 369 first->tqe_m = m; 370 first->tqe_len += tlen; 371 first->tqe_start = th->th_seq; 372 first->tqe_m->m_pkthdr.len = first->tqe_len; 373 first->tqe_mbuf_cnt += lenofoh; 374 tp->t_rcvoopack++; 375 TCPSTAT_INC(tcps_rcvoopack); 376 TCPSTAT_ADD(tcps_rcvoobyte, tlen); 377 #ifdef TCP_REASS_LOGGING 378 tcp_reass_log_new_in(tp, first->tqe_start, lenofoh, first->tqe_m, 379 TCP_R_LOG_PREPEND, 380 first); 381 #endif 382 } 383 384 static void 385 tcp_reass_replace(struct tcpcb *tp, struct tseg_qent *q, struct mbuf *m, 386 tcp_seq seq, int len, struct mbuf *mlast, int mbufoh, uint8_t flags) 387 { 388 /* 389 * Free the data in q, and replace 390 * it with the new segment. 391 */ 392 int len_dif; 393 394 #ifdef TCP_REASS_LOGGING 395 tcp_log_reassm(tp, q, NULL, seq, len, TCP_R_LOG_REPLACE, 0); 396 #endif 397 m_freem(q->tqe_m); 398 KASSERT(tp->t_segqmbuflen >= q->tqe_mbuf_cnt, 399 ("Tp:%p seg queue goes negative", tp)); 400 tp->t_segqmbuflen -= q->tqe_mbuf_cnt; 401 q->tqe_mbuf_cnt = mbufoh; 402 q->tqe_m = m; 403 q->tqe_last = mlast; 404 q->tqe_start = seq; 405 if (len > q->tqe_len) 406 len_dif = len - q->tqe_len; 407 else 408 len_dif = 0; 409 tp->t_rcvoopack++; 410 TCPSTAT_INC(tcps_rcvoopack); 411 TCPSTAT_ADD(tcps_rcvoobyte, len_dif); 412 q->tqe_len = len; 413 q->tqe_flags = (flags & TH_FIN); 414 q->tqe_m->m_pkthdr.len = q->tqe_len; 415 tp->t_segqmbuflen += mbufoh; 416 417 } 418 419 static void 420 tcp_reass_merge_into(struct tcpcb *tp, struct tseg_qent *ent, 421 struct tseg_qent *q) 422 { 423 /* 424 * Merge q into ent and free q from the list. 425 */ 426 #ifdef TCP_REASS_LOGGING 427 tcp_log_reassm(tp, q, ent, 0, 0, TCP_R_LOG_MERGE_INTO, 0); 428 #endif 429 #ifdef TCP_REASS_COUNTERS 430 counter_u64_add(merge_into, 1); 431 #endif 432 ent->tqe_last->m_next = q->tqe_m; 433 ent->tqe_last = q->tqe_last; 434 ent->tqe_len += q->tqe_len; 435 ent->tqe_mbuf_cnt += q->tqe_mbuf_cnt; 436 ent->tqe_m->m_pkthdr.len += q->tqe_len; 437 ent->tqe_flags |= (q->tqe_flags & TH_FIN); 438 TAILQ_REMOVE(&tp->t_segq, q, tqe_q); 439 uma_zfree(tcp_reass_zone, q); 440 tp->t_segqlen--; 441 442 } 443 444 static void 445 tcp_reass_merge_forward(struct tcpcb *tp, struct tseg_qent *ent) 446 { 447 struct tseg_qent *q, *qtmp; 448 int i; 449 tcp_seq max; 450 /* 451 * Given an entry merge forward anyplace 452 * that ent overlaps forward. 453 */ 454 455 max = ent->tqe_start + ent->tqe_len; 456 q = TAILQ_NEXT(ent, tqe_q); 457 if (q == NULL) { 458 /* Nothing left */ 459 return; 460 } 461 TAILQ_FOREACH_FROM_SAFE(q, &tp->t_segq, tqe_q, qtmp) { 462 if (SEQ_GT(q->tqe_start, max)) { 463 /* Beyond q */ 464 break; 465 } 466 /* We have some or all that are overlapping */ 467 if (SEQ_GEQ(max, (q->tqe_start + q->tqe_len))) { 468 /* It consumes it all */ 469 tp->t_segqmbuflen -= q->tqe_mbuf_cnt; 470 m_freem(q->tqe_m); 471 TAILQ_REMOVE(&tp->t_segq, q, tqe_q); 472 uma_zfree(tcp_reass_zone, q); 473 tp->t_segqlen--; 474 continue; 475 } 476 /* 477 * Trim the q entry to dovetail to this one 478 * and then merge q into ent updating max 479 * in the process. 480 */ 481 i = max - q->tqe_start; 482 #ifdef TCP_REASS_LOGGING 483 tcp_log_reassm(tp, q, NULL, 0, i, TCP_R_LOG_TRIM, 2); 484 #endif 485 m_adj(q->tqe_m, i); 486 q->tqe_len -= i; 487 q->tqe_start += i; 488 tcp_reass_merge_into(tp, ent, q); 489 max = ent->tqe_start + ent->tqe_len; 490 } 491 #ifdef TCP_REASS_COUNTERS 492 counter_u64_add(merge_fwd, 1); 493 #endif 494 } 495 496 static int 497 tcp_reass_overhead_of_chain(struct mbuf *m, struct mbuf **mlast) 498 { 499 int len = MSIZE; 500 501 if (m->m_flags & M_EXT) 502 len += m->m_ext.ext_size; 503 while (m->m_next != NULL) { 504 m = m->m_next; 505 len += MSIZE; 506 if (m->m_flags & M_EXT) 507 len += m->m_ext.ext_size; 508 } 509 *mlast = m; 510 return (len); 511 } 512 513 514 /* 515 * NOTE!!! the new tcp-reassembly code *must not* use 516 * m_adj() with a negative index. That alters the chain 517 * of mbufs (by possibly chopping trailing mbufs). At 518 * the front of tcp_reass we count the mbuf overhead 519 * and setup the tail pointer. If we use m_adj(m, -5) 520 * we could corrupt the tail pointer. Currently the 521 * code only uses m_adj(m, postive-num). If this 522 * changes appropriate changes to update mlast would 523 * be needed. 524 */ 525 int 526 tcp_reass(struct tcpcb *tp, struct tcphdr *th, tcp_seq *seq_start, 527 int *tlenp, struct mbuf *m) 528 { 529 struct tseg_qent *q, *last, *first; 530 struct tseg_qent *p = NULL; 531 struct tseg_qent *nq = NULL; 532 struct tseg_qent *te = NULL; 533 struct mbuf *mlast = NULL; 534 struct sockbuf *sb; 535 struct socket *so = tp->t_inpcb->inp_socket; 536 char *s = NULL; 537 int flags, i, lenofoh; 538 539 INP_WLOCK_ASSERT(tp->t_inpcb); 540 /* 541 * XXX: tcp_reass() is rather inefficient with its data structures 542 * and should be rewritten (see NetBSD for optimizations). 543 */ 544 545 KASSERT(th == NULL || (seq_start != NULL && tlenp != NULL), 546 ("tcp_reass called with illegal parameter combination " 547 "(tp=%p, th=%p, seq_start=%p, tlenp=%p, m=%p)", 548 tp, th, seq_start, tlenp, m)); 549 /* 550 * Call with th==NULL after become established to 551 * force pre-ESTABLISHED data up to user socket. 552 */ 553 if (th == NULL) 554 goto present; 555 KASSERT(SEQ_GEQ(th->th_seq, tp->rcv_nxt), 556 ("Attempt to add old entry to reassembly queue (th=%p, tp=%p)", 557 th, tp)); 558 #ifdef TCP_REASS_LOGGING 559 tcp_reass_log_new_in(tp, th->th_seq, *tlenp, m, TCP_R_LOG_ADD, NULL); 560 #endif 561 #ifdef TCP_REASS_COUNTERS 562 counter_u64_add(reass_entry, 1); 563 #endif 564 /* 565 * Check for zero length data. 566 */ 567 if ((*tlenp == 0) && ((th->th_flags & TH_FIN) == 0)) { 568 /* 569 * A zero length segment does no 570 * one any good. We could check 571 * the rcv_nxt <-> rcv_wnd but thats 572 * already done for us by the caller. 573 */ 574 #ifdef TCP_REASS_COUNTERS 575 counter_u64_add(tcp_zero_input, 1); 576 #endif 577 m_freem(m); 578 #ifdef TCP_REASS_LOGGING 579 tcp_reass_log_dump(tp); 580 #endif 581 return (0); 582 } 583 /* 584 * Will it fit? 585 */ 586 lenofoh = tcp_reass_overhead_of_chain(m, &mlast); 587 sb = &tp->t_inpcb->inp_socket->so_rcv; 588 if ((th->th_seq != tp->rcv_nxt || !TCPS_HAVEESTABLISHED(tp->t_state)) && 589 (sb->sb_mbcnt + tp->t_segqmbuflen + lenofoh) > sb->sb_mbmax) { 590 /* No room */ 591 TCPSTAT_INC(tcps_rcvreassfull); 592 #ifdef TCP_REASS_COUNTERS 593 counter_u64_add(reass_nospace, 1); 594 #endif 595 #ifdef TCP_REASS_LOGGING 596 tcp_log_reassm(tp, NULL, NULL, th->th_seq, lenofoh, TCP_R_LOG_LIMIT_REACHED, 0); 597 #endif 598 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) { 599 log(LOG_DEBUG, "%s; %s: mbuf count limit reached, " 600 "segment dropped\n", s, __func__); 601 free(s, M_TCPLOG); 602 } 603 m_freem(m); 604 *tlenp = 0; 605 #ifdef TCP_REASS_LOGGING 606 tcp_reass_log_dump(tp); 607 #endif 608 return (0); 609 } 610 /* 611 * First lets deal with two common cases, the 612 * segment appends to the back of our collected 613 * segments. Or the segment is the next in line. 614 */ 615 last = TAILQ_LAST_FAST(&tp->t_segq, tseg_qent, tqe_q); 616 if (last != NULL) { 617 if ((th->th_flags & TH_FIN) && 618 SEQ_LT((th->th_seq + *tlenp), (last->tqe_start + last->tqe_len))) { 619 /* 620 * Someone is trying to game us, dump 621 * the segment. 622 */ 623 *tlenp = 0; 624 m_freem(m); 625 return (0); 626 } 627 if ((SEQ_GEQ(th->th_seq, last->tqe_start)) && 628 (SEQ_GEQ((last->tqe_start + last->tqe_len), th->th_seq))) { 629 /* Common case, trailing segment is added */ 630 /** 631 * +--last 632 * v 633 * reassembly buffer |---| |---| |---| 634 * new segment |---| 635 */ 636 #ifdef TCP_REASS_COUNTERS 637 counter_u64_add(reass_path1, 1); 638 #endif 639 if (SEQ_GT((last->tqe_start + last->tqe_len), th->th_seq)) { 640 i = (last->tqe_start + last->tqe_len) - th->th_seq; 641 if (i < *tlenp) { 642 #ifdef TCP_REASS_LOGGING 643 tcp_log_reassm(tp, last, NULL, 0, i, TCP_R_LOG_TRIM, 3); 644 th->th_seq += i; 645 #endif 646 m_adj(m, i); 647 *tlenp -= i; 648 } else { 649 /* Complete overlap */ 650 TCPSTAT_INC(tcps_rcvduppack); 651 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp); 652 m_freem(m); 653 *tlenp = last->tqe_len; 654 *seq_start = last->tqe_start; 655 return (0); 656 } 657 } 658 if (last->tqe_flags & TH_FIN) { 659 /* 660 * We have data after the FIN on the last? 661 */ 662 *tlenp = 0; 663 m_freem(m); 664 return(0); 665 } 666 tcp_reass_append(tp, last, m, th, *tlenp, mlast, lenofoh); 667 tp->t_segqmbuflen += lenofoh; 668 *seq_start = last->tqe_start; 669 *tlenp = last->tqe_len; 670 return (0); 671 } else if (SEQ_GT(th->th_seq, (last->tqe_start + last->tqe_len))) { 672 /* 673 * Second common case, we missed 674 * another one and have something more 675 * for the end. 676 */ 677 /** 678 * +--last 679 * v 680 * reassembly buffer |---| |---| |---| 681 * new segment |---| 682 */ 683 if (last->tqe_flags & TH_FIN) { 684 /* 685 * We have data after the FIN on the last? 686 */ 687 *tlenp = 0; 688 m_freem(m); 689 return(0); 690 } 691 #ifdef TCP_REASS_COUNTERS 692 counter_u64_add(reass_path2, 1); 693 #endif 694 p = last; 695 goto new_entry; 696 } 697 } else { 698 /* First segment (it's NULL). */ 699 goto new_entry; 700 } 701 first = TAILQ_FIRST(&tp->t_segq); 702 if (SEQ_LT(th->th_seq, first->tqe_start) && 703 SEQ_GEQ((th->th_seq + *tlenp),first->tqe_start) && 704 SEQ_LT((th->th_seq + *tlenp), (first->tqe_start + first->tqe_len))) { 705 /* 706 * The head of the queue is prepended by this and 707 * it may be the one I want most. 708 */ 709 /** 710 * first-------+ 711 * v 712 * rea: |---| |---| |---| 713 * new: |---| 714 * Note the case we do not deal with here is: 715 * rea= |---| |---| |---| 716 * new= |----| 717 * Due to the fact that it could be 718 * new |--------------------| 719 * And we might need to merge forward. 720 */ 721 #ifdef INVARIANTS 722 struct mbuf *firstmbuf; 723 #endif 724 725 #ifdef TCP_REASS_COUNTERS 726 counter_u64_add(reass_path3, 1); 727 #endif 728 if (SEQ_LT(th->th_seq, tp->rcv_nxt)) { 729 /* 730 * The resend was even before 731 * what we have. We need to trim it. 732 * Note TSNH (it should be trimmed 733 * before the call to tcp_reass()). 734 */ 735 #ifdef INVARIANTS 736 panic("th->th_seq:%u rcv_nxt:%u tp:%p not pre-trimmed", 737 th->th_seq, tp->rcv_nxt, tp); 738 #else 739 i = tp->rcv_nxt - th->th_seq; 740 #ifdef TCP_REASS_LOGGING 741 tcp_log_reassm(tp, first, NULL, 0, i, TCP_R_LOG_TRIM, 4); 742 #endif 743 m_adj(m, i); 744 th->th_seq += i; 745 *tlenp -= i; 746 #endif 747 } 748 #ifdef INVARIANTS 749 firstmbuf = first->tqe_m; 750 #endif 751 tcp_reass_prepend(tp, first, m, th, *tlenp, mlast, lenofoh); 752 #ifdef INVARIANTS 753 if (firstmbuf == first->tqe_m) { 754 panic("First stayed same m:%p foobar:%p first->tqe_m:%p tp:%p first:%p", 755 m, firstmbuf, first->tqe_m, tp, first); 756 } else if (first->tqe_m != m) { 757 panic("First did not change to m:%p foobar:%p first->tqe_m:%p tp:%p first:%p", 758 m, firstmbuf, first->tqe_m, tp, first); 759 } 760 #endif 761 tp->t_segqmbuflen += lenofoh; 762 *seq_start = first->tqe_start; 763 *tlenp = first->tqe_len; 764 goto present; 765 } else if (SEQ_LT((th->th_seq + *tlenp), first->tqe_start)) { 766 /* New segment is before our earliest segment. */ 767 /** 768 * first---->+ 769 * v 770 * rea= |---| .... 771 * new" |---| 772 * 773 */ 774 goto new_entry; 775 } 776 /* 777 * Find a segment which begins after this one does. 778 */ 779 #ifdef TCP_REASS_COUNTERS 780 counter_u64_add(reass_fullwalk, 1); 781 #endif 782 TAILQ_FOREACH(q, &tp->t_segq, tqe_q) { 783 if (SEQ_GT(q->tqe_start, th->th_seq)) 784 break; 785 } 786 p = TAILQ_PREV(q, tsegqe_head, tqe_q); 787 /** 788 * Now is this fit just in-between only? 789 * i.e.: 790 * p---+ +----q 791 * v v 792 * res= |--| |--| |--| 793 * nee |-| 794 */ 795 if (SEQ_LT((th->th_seq + *tlenp), q->tqe_start) && 796 ((p == NULL) || (SEQ_GT(th->th_seq, (p->tqe_start + p->tqe_len))))) { 797 /* Yep no overlap */ 798 goto new_entry; 799 } 800 /** 801 * If we reach here we have some (possibly all) overlap 802 * such as: 803 * res= |--| |--| |--| 804 * new= |----| 805 * or new= |-----------------| 806 * or new= |--------| 807 * or new= |---| 808 * or new= |-----------| 809 */ 810 if ((p != NULL) && 811 (SEQ_LEQ(th->th_seq, (p->tqe_start + p->tqe_len)))) { 812 /* conversion to int (in i) handles seq wraparound */ 813 814 #ifdef TCP_REASS_COUNTERS 815 counter_u64_add(reass_path4, 1); 816 #endif 817 i = p->tqe_start + p->tqe_len - th->th_seq; 818 if (i >= 0) { 819 if (i >= *tlenp) { 820 /** 821 * prev seg---->+ 822 * v 823 * reassembly buffer |---| 824 * new segment |-| 825 */ 826 TCPSTAT_INC(tcps_rcvduppack); 827 TCPSTAT_ADD(tcps_rcvdupbyte, *tlenp); 828 *tlenp = p->tqe_len; 829 *seq_start = p->tqe_start; 830 m_freem(m); 831 /* 832 * Try to present any queued data 833 * at the left window edge to the user. 834 * This is needed after the 3-WHS 835 * completes. Note this probably 836 * will not work and we will return. 837 */ 838 return (0); 839 } 840 if (i > 0) { 841 /** 842 * prev seg---->+ 843 * v 844 * reassembly buffer |---| 845 * new segment |-----| 846 */ 847 #ifdef TCP_REASS_COUNTERS 848 counter_u64_add(reass_path5, 1); 849 #endif 850 #ifdef TCP_REASS_LOGGING 851 tcp_log_reassm(tp, p, NULL, 0, i, TCP_R_LOG_TRIM, 5); 852 #endif 853 m_adj(m, i); 854 *tlenp -= i; 855 th->th_seq += i; 856 } 857 } 858 if (th->th_seq == (p->tqe_start + p->tqe_len)) { 859 /* 860 * If dovetails in with this one 861 * append it. 862 */ 863 /** 864 * prev seg---->+ 865 * v 866 * reassembly buffer |--| |---| 867 * new segment |--| 868 * (note: it was trimmed above if it overlapped) 869 */ 870 tcp_reass_append(tp, p, m, th, *tlenp, mlast, lenofoh); 871 tp->t_segqmbuflen += lenofoh; 872 } else { 873 #ifdef INVARIANTS 874 panic("Impossible cut th_seq:%u p->seq:%u(%d) p:%p tp:%p", 875 th->th_seq, p->tqe_start, p->tqe_len, 876 p, tp); 877 #endif 878 *tlenp = 0; 879 m_freem(m); 880 return (0); 881 } 882 q = p; 883 } else { 884 /* 885 * The new data runs over the 886 * top of previously sack'd data (in q). 887 * It may be partially overlapping, or 888 * it may overlap the entire segment. 889 */ 890 #ifdef TCP_REASS_COUNTERS 891 counter_u64_add(reass_path6, 1); 892 #endif 893 if (SEQ_GEQ((th->th_seq + *tlenp), (q->tqe_start + q->tqe_len))) { 894 /* It consumes it all */ 895 /** 896 * next seg---->+ 897 * v 898 * reassembly buffer |--| |---| 899 * new segment |----------| 900 */ 901 #ifdef TCP_REASS_COUNTERS 902 counter_u64_add(reass_path7, 1); 903 #endif 904 tcp_reass_replace(tp, q, m, th->th_seq, *tlenp, mlast, lenofoh, th->th_flags); 905 } else { 906 /* 907 * We just need to prepend the data 908 * to this. It does not overrun 909 * the end. 910 */ 911 /** 912 * next seg---->+ 913 * v 914 * reassembly buffer |--| |---| 915 * new segment |----------| 916 */ 917 tcp_reass_prepend(tp, q, m, th, *tlenp, mlast, lenofoh); 918 tp->t_segqmbuflen += lenofoh; 919 } 920 } 921 /* Now does it go further than that? */ 922 tcp_reass_merge_forward(tp, q); 923 *seq_start = q->tqe_start; 924 *tlenp = q->tqe_len; 925 goto present; 926 927 /* 928 * When we reach here we can't combine it 929 * with any existing segment. 930 * 931 * Limit the number of segments that can be queued to reduce the 932 * potential for mbuf exhaustion. For best performance, we want to be 933 * able to queue a full window's worth of segments. The size of the 934 * socket receive buffer determines our advertised window and grows 935 * automatically when socket buffer autotuning is enabled. Use it as the 936 * basis for our queue limit. 937 * 938 * However, allow the user to specify a ceiling for the number of 939 * segments in each queue. 940 * 941 * Always let the missing segment through which caused this queue. 942 * NB: Access to the socket buffer is left intentionally unlocked as we 943 * can tolerate stale information here. 944 * 945 * XXXLAS: Using sbspace(so->so_rcv) instead of so->so_rcv.sb_hiwat 946 * should work but causes packets to be dropped when they shouldn't. 947 * Investigate why and re-evaluate the below limit after the behaviour 948 * is understood. 949 */ 950 new_entry: 951 if (th->th_seq == tp->rcv_nxt && TCPS_HAVEESTABLISHED(tp->t_state)) { 952 tp->rcv_nxt += *tlenp; 953 flags = th->th_flags & TH_FIN; 954 TCPSTAT_INC(tcps_rcvoopack); 955 TCPSTAT_ADD(tcps_rcvoobyte, *tlenp); 956 SOCKBUF_LOCK(&so->so_rcv); 957 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 958 m_freem(m); 959 } else { 960 sbappendstream_locked(&so->so_rcv, m, 0); 961 } 962 sorwakeup_locked(so); 963 return (flags); 964 } 965 if (tcp_new_limits) { 966 if ((tp->t_segqlen > tcp_reass_queue_guard) && 967 (*tlenp < MSIZE)) { 968 /* 969 * This is really a lie, we are not full but 970 * are getting a segment that is above 971 * guard threshold. If it is and its below 972 * a mbuf size (256) we drop it if it 973 * can't fill in some place. 974 */ 975 TCPSTAT_INC(tcps_rcvreassfull); 976 *tlenp = 0; 977 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) { 978 log(LOG_DEBUG, "%s; %s: queue limit reached, " 979 "segment dropped\n", s, __func__); 980 free(s, M_TCPLOG); 981 } 982 m_freem(m); 983 #ifdef TCP_REASS_LOGGING 984 tcp_reass_log_dump(tp); 985 #endif 986 return (0); 987 } 988 } else { 989 if (tp->t_segqlen >= min((so->so_rcv.sb_hiwat / tp->t_maxseg) + 1, 990 tcp_reass_maxqueuelen)) { 991 TCPSTAT_INC(tcps_rcvreassfull); 992 *tlenp = 0; 993 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, NULL))) { 994 log(LOG_DEBUG, "%s; %s: queue limit reached, " 995 "segment dropped\n", s, __func__); 996 free(s, M_TCPLOG); 997 } 998 m_freem(m); 999 #ifdef TCP_REASS_LOGGING 1000 tcp_reass_log_dump(tp); 1001 #endif 1002 return (0); 1003 } 1004 } 1005 /* 1006 * Allocate a new queue entry. If we can't, or hit the zone limit 1007 * just drop the pkt. 1008 */ 1009 te = uma_zalloc(tcp_reass_zone, M_NOWAIT); 1010 if (te == NULL) { 1011 TCPSTAT_INC(tcps_rcvmemdrop); 1012 m_freem(m); 1013 *tlenp = 0; 1014 if ((s = tcp_log_addrs(&tp->t_inpcb->inp_inc, th, NULL, 1015 NULL))) { 1016 log(LOG_DEBUG, "%s; %s: global zone limit " 1017 "reached, segment dropped\n", s, __func__); 1018 free(s, M_TCPLOG); 1019 } 1020 return (0); 1021 } 1022 tp->t_segqlen++; 1023 tp->t_rcvoopack++; 1024 TCPSTAT_INC(tcps_rcvoopack); 1025 TCPSTAT_ADD(tcps_rcvoobyte, *tlenp); 1026 /* Insert the new segment queue entry into place. */ 1027 te->tqe_m = m; 1028 te->tqe_flags = th->th_flags; 1029 te->tqe_len = *tlenp; 1030 te->tqe_start = th->th_seq; 1031 te->tqe_last = mlast; 1032 te->tqe_mbuf_cnt = lenofoh; 1033 tp->t_segqmbuflen += te->tqe_mbuf_cnt; 1034 if (p == NULL) { 1035 TAILQ_INSERT_HEAD(&tp->t_segq, te, tqe_q); 1036 } else { 1037 TAILQ_INSERT_AFTER(&tp->t_segq, p, te, tqe_q); 1038 } 1039 #ifdef TCP_REASS_LOGGING 1040 tcp_reass_log_new_in(tp, th->th_seq, *tlenp, m, TCP_R_LOG_NEW_ENTRY, te); 1041 #endif 1042 present: 1043 /* 1044 * Present data to user, advancing rcv_nxt through 1045 * completed sequence space. 1046 */ 1047 if (!TCPS_HAVEESTABLISHED(tp->t_state)) 1048 return (0); 1049 q = TAILQ_FIRST(&tp->t_segq); 1050 KASSERT(q == NULL || SEQ_GEQ(q->tqe_start, tp->rcv_nxt), 1051 ("Reassembly queue for %p has stale entry at head", tp)); 1052 if (!q || q->tqe_start != tp->rcv_nxt) { 1053 #ifdef TCP_REASS_LOGGING 1054 tcp_reass_log_dump(tp); 1055 #endif 1056 return (0); 1057 } 1058 SOCKBUF_LOCK(&so->so_rcv); 1059 do { 1060 tp->rcv_nxt += q->tqe_len; 1061 flags = q->tqe_flags & TH_FIN; 1062 nq = TAILQ_NEXT(q, tqe_q); 1063 TAILQ_REMOVE(&tp->t_segq, q, tqe_q); 1064 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 1065 m_freem(q->tqe_m); 1066 } else { 1067 #ifdef TCP_REASS_LOGGING 1068 tcp_reass_log_new_in(tp, q->tqe_start, q->tqe_len, q->tqe_m, TCP_R_LOG_READ, q); 1069 if (th != NULL) { 1070 tcp_log_reassm(tp, q, NULL, th->th_seq, *tlenp, TCP_R_LOG_READ, 1); 1071 } else { 1072 tcp_log_reassm(tp, q, NULL, 0, 0, TCP_R_LOG_READ, 1); 1073 } 1074 #endif 1075 sbappendstream_locked(&so->so_rcv, q->tqe_m, 0); 1076 } 1077 #ifdef TCP_REASS_LOGGING 1078 if (th != NULL) { 1079 tcp_log_reassm(tp, q, NULL, th->th_seq, *tlenp, TCP_R_LOG_READ, 2); 1080 } else { 1081 tcp_log_reassm(tp, q, NULL, 0, 0, TCP_R_LOG_READ, 2); 1082 } 1083 #endif 1084 KASSERT(tp->t_segqmbuflen >= q->tqe_mbuf_cnt, 1085 ("tp:%p seg queue goes negative", tp)); 1086 tp->t_segqmbuflen -= q->tqe_mbuf_cnt; 1087 uma_zfree(tcp_reass_zone, q); 1088 tp->t_segqlen--; 1089 q = nq; 1090 } while (q && q->tqe_start == tp->rcv_nxt); 1091 if (TAILQ_EMPTY(&tp->t_segq) && 1092 (tp->t_segqmbuflen != 0)) { 1093 #ifdef INVARIANTS 1094 panic("tp:%p segq:%p len:%d queue empty", 1095 tp, &tp->t_segq, tp->t_segqmbuflen); 1096 #else 1097 #ifdef TCP_REASS_LOGGING 1098 if (th != NULL) { 1099 tcp_log_reassm(tp, NULL, NULL, th->th_seq, *tlenp, TCP_R_LOG_ZERO, 0); 1100 } else { 1101 tcp_log_reassm(tp, NULL, NULL, 0, 0, TCP_R_LOG_ZERO, 0); 1102 } 1103 #endif 1104 tp->t_segqmbuflen = 0; 1105 #endif 1106 } 1107 #ifdef TCP_REASS_LOGGING 1108 tcp_reass_log_dump(tp); 1109 #endif 1110 sorwakeup_locked(so); 1111 return (flags); 1112 }
Cache object: 23c9e28a68c31b275a51c4258dca2a06
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