tcp_input.c revision 1.440
1 /* $NetBSD: tcp_input.c,v 1.440 2024/07/05 04:31:54 rin Exp $ */ 2 3 /* 4 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. 5 * 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 project 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 PROJECT 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 PROJECT 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 32 /* 33 * @(#)COPYRIGHT 1.1 (NRL) 17 January 1995 34 * 35 * NRL grants permission for redistribution and use in source and binary 36 * forms, with or without modification, of the software and documentation 37 * created at NRL provided that the following conditions are met: 38 * 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 * 3. All advertising materials mentioning features or use of this software 45 * must display the following acknowledgements: 46 * This product includes software developed by the University of 47 * California, Berkeley and its contributors. 48 * This product includes software developed at the Information 49 * Technology Division, US Naval Research Laboratory. 50 * 4. Neither the name of the NRL nor the names of its contributors 51 * may be used to endorse or promote products derived from this software 52 * without specific prior written permission. 53 * 54 * THE SOFTWARE PROVIDED BY NRL IS PROVIDED BY NRL AND CONTRIBUTORS ``AS 55 * IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 56 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A 57 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL NRL OR 58 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 59 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 60 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 61 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF 62 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 63 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 64 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 65 * 66 * The views and conclusions contained in the software and documentation 67 * are those of the authors and should not be interpreted as representing 68 * official policies, either expressed or implied, of the US Naval 69 * Research Laboratory (NRL). 70 */ 71 72 /*- 73 * Copyright (c) 1997, 1998, 1999, 2001, 2005, 2006, 74 * 2011 The NetBSD Foundation, Inc. 75 * All rights reserved. 76 * 77 * This code is derived from software contributed to The NetBSD Foundation 78 * by Coyote Point Systems, Inc. 79 * This code is derived from software contributed to The NetBSD Foundation 80 * by Jason R. Thorpe and Kevin M. Lahey of the Numerical Aerospace Simulation 81 * Facility, NASA Ames Research Center. 82 * This code is derived from software contributed to The NetBSD Foundation 83 * by Charles M. Hannum. 84 * This code is derived from software contributed to The NetBSD Foundation 85 * by Rui Paulo. 86 * 87 * Redistribution and use in source and binary forms, with or without 88 * modification, are permitted provided that the following conditions 89 * are met: 90 * 1. Redistributions of source code must retain the above copyright 91 * notice, this list of conditions and the following disclaimer. 92 * 2. Redistributions in binary form must reproduce the above copyright 93 * notice, this list of conditions and the following disclaimer in the 94 * documentation and/or other materials provided with the distribution. 95 * 96 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 97 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 98 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 99 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 100 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 101 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 102 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 103 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 104 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 105 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 106 * POSSIBILITY OF SUCH DAMAGE. 107 */ 108 109 /* 110 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995 111 * The Regents of the University of California. All rights reserved. 112 * 113 * Redistribution and use in source and binary forms, with or without 114 * modification, are permitted provided that the following conditions 115 * are met: 116 * 1. Redistributions of source code must retain the above copyright 117 * notice, this list of conditions and the following disclaimer. 118 * 2. Redistributions in binary form must reproduce the above copyright 119 * notice, this list of conditions and the following disclaimer in the 120 * documentation and/or other materials provided with the distribution. 121 * 3. Neither the name of the University nor the names of its contributors 122 * may be used to endorse or promote products derived from this software 123 * without specific prior written permission. 124 * 125 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 126 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 127 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 128 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 129 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 130 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 131 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 132 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 133 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 134 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 135 * SUCH DAMAGE. 136 * 137 * @(#)tcp_input.c 8.12 (Berkeley) 5/24/95 138 */ 139 140 #include <sys/cdefs.h> 141 __KERNEL_RCSID(0, "$NetBSD: tcp_input.c,v 1.440 2024/07/05 04:31:54 rin Exp $"); 142 143 #ifdef _KERNEL_OPT 144 #include "opt_inet.h" 145 #include "opt_ipsec.h" 146 #include "opt_inet_csum.h" 147 #include "opt_tcp_debug.h" 148 #endif 149 150 #include <sys/param.h> 151 #include <sys/systm.h> 152 #include <sys/malloc.h> 153 #include <sys/mbuf.h> 154 #include <sys/protosw.h> 155 #include <sys/socket.h> 156 #include <sys/socketvar.h> 157 #include <sys/errno.h> 158 #include <sys/syslog.h> 159 #include <sys/pool.h> 160 #include <sys/domain.h> 161 #include <sys/kernel.h> 162 #ifdef TCP_SIGNATURE 163 #include <sys/md5.h> 164 #endif 165 #include <sys/lwp.h> /* for lwp0 */ 166 #include <sys/cprng.h> 167 168 #include <net/if.h> 169 #include <net/if_types.h> 170 171 #include <netinet/in.h> 172 #include <netinet/in_systm.h> 173 #include <netinet/ip.h> 174 #include <netinet/in_pcb.h> 175 #include <netinet/in_var.h> 176 #include <netinet/ip_var.h> 177 #include <netinet/in_offload.h> 178 179 #if NARP > 0 180 #include <netinet/if_inarp.h> 181 #endif 182 #ifdef INET6 183 #include <netinet/ip6.h> 184 #include <netinet6/ip6_var.h> 185 #include <netinet6/in6_pcb.h> 186 #include <netinet6/ip6_var.h> 187 #include <netinet6/in6_var.h> 188 #include <netinet/icmp6.h> 189 #include <netinet6/nd6.h> 190 #ifdef TCP_SIGNATURE 191 #include <netinet6/scope6_var.h> 192 #endif 193 #endif 194 195 #ifndef INET6 196 #include <netinet/ip6.h> 197 #endif 198 199 #include <netinet/tcp.h> 200 #include <netinet/tcp_fsm.h> 201 #include <netinet/tcp_seq.h> 202 #include <netinet/tcp_timer.h> 203 #include <netinet/tcp_var.h> 204 #include <netinet/tcp_private.h> 205 #include <netinet/tcp_congctl.h> 206 #include <netinet/tcp_debug.h> 207 #include <netinet/tcp_syncache.h> 208 209 #ifdef INET6 210 #include "faith.h" 211 #if defined(NFAITH) && NFAITH > 0 212 #include <net/if_faith.h> 213 #endif 214 #endif 215 216 #ifdef IPSEC 217 #include <netipsec/ipsec.h> 218 #include <netipsec/key.h> 219 #ifdef INET6 220 #include <netipsec/ipsec6.h> 221 #endif 222 #endif /* IPSEC*/ 223 224 #include <netinet/tcp_vtw.h> 225 226 int tcprexmtthresh = 3; 227 int tcp_log_refused; 228 229 int tcp_do_autorcvbuf = 1; 230 int tcp_autorcvbuf_inc = 16 * 1024; 231 int tcp_autorcvbuf_max = 256 * 1024; 232 int tcp_msl = (TCPTV_MSL / PR_SLOWHZ); 233 234 static int tcp_rst_ppslim_count = 0; 235 static struct timeval tcp_rst_ppslim_last; 236 static int tcp_ackdrop_ppslim_count = 0; 237 static struct timeval tcp_ackdrop_ppslim_last; 238 239 #define TCP_PAWS_IDLE (24U * 24 * 60 * 60 * PR_SLOWHZ) 240 241 /* for modulo comparisons of timestamps */ 242 #define TSTMP_LT(a,b) ((int)((a)-(b)) < 0) 243 #define TSTMP_GEQ(a,b) ((int)((a)-(b)) >= 0) 244 245 /* 246 * Neighbor Discovery, Neighbor Unreachability Detection Upper layer hint. 247 */ 248 static void 249 nd_hint(struct tcpcb *tp) 250 { 251 struct route *ro = NULL; 252 struct rtentry *rt; 253 254 if (tp == NULL) 255 return; 256 257 ro = &tp->t_inpcb->inp_route; 258 if (ro == NULL) 259 return; 260 261 rt = rtcache_validate(ro); 262 if (rt == NULL) 263 return; 264 265 switch (tp->t_family) { 266 #if NARP > 0 267 case AF_INET: 268 arp_nud_hint(rt); 269 break; 270 #endif 271 #ifdef INET6 272 case AF_INET6: 273 nd6_nud_hint(rt); 274 break; 275 #endif 276 } 277 278 rtcache_unref(rt, ro); 279 } 280 281 /* 282 * Compute ACK transmission behavior. Delay the ACK unless 283 * we have already delayed an ACK (must send an ACK every two segments). 284 * We also ACK immediately if we received a PUSH and the ACK-on-PUSH 285 * option is enabled. 286 */ 287 static void 288 tcp_setup_ack(struct tcpcb *tp, const struct tcphdr *th) 289 { 290 291 if (tp->t_flags & TF_DELACK || 292 (tcp_ack_on_push && th->th_flags & TH_PUSH)) 293 tp->t_flags |= TF_ACKNOW; 294 else 295 TCP_SET_DELACK(tp); 296 } 297 298 static void 299 icmp_check(struct tcpcb *tp, const struct tcphdr *th, int acked) 300 { 301 302 /* 303 * If we had a pending ICMP message that refers to data that have 304 * just been acknowledged, disregard the recorded ICMP message. 305 */ 306 if ((tp->t_flags & TF_PMTUD_PEND) && 307 SEQ_GT(th->th_ack, tp->t_pmtud_th_seq)) 308 tp->t_flags &= ~TF_PMTUD_PEND; 309 310 /* 311 * Keep track of the largest chunk of data 312 * acknowledged since last PMTU update 313 */ 314 if (tp->t_pmtud_mss_acked < acked) 315 tp->t_pmtud_mss_acked = acked; 316 } 317 318 /* 319 * Convert TCP protocol fields to host order for easier processing. 320 */ 321 static void 322 tcp_fields_to_host(struct tcphdr *th) 323 { 324 325 NTOHL(th->th_seq); 326 NTOHL(th->th_ack); 327 NTOHS(th->th_win); 328 NTOHS(th->th_urp); 329 } 330 331 /* 332 * ... and reverse the above. 333 */ 334 static void 335 tcp_fields_to_net(struct tcphdr *th) 336 { 337 338 HTONL(th->th_seq); 339 HTONL(th->th_ack); 340 HTONS(th->th_win); 341 HTONS(th->th_urp); 342 } 343 344 static void 345 tcp_urp_drop(struct tcphdr *th, int todrop, int *tiflags) 346 { 347 if (th->th_urp > todrop) { 348 th->th_urp -= todrop; 349 } else { 350 *tiflags &= ~TH_URG; 351 th->th_urp = 0; 352 } 353 } 354 355 #ifdef TCP_CSUM_COUNTERS 356 #include <sys/device.h> 357 358 extern struct evcnt tcp_hwcsum_ok; 359 extern struct evcnt tcp_hwcsum_bad; 360 extern struct evcnt tcp_hwcsum_data; 361 extern struct evcnt tcp_swcsum; 362 #if defined(INET6) 363 extern struct evcnt tcp6_hwcsum_ok; 364 extern struct evcnt tcp6_hwcsum_bad; 365 extern struct evcnt tcp6_hwcsum_data; 366 extern struct evcnt tcp6_swcsum; 367 #endif /* defined(INET6) */ 368 369 #define TCP_CSUM_COUNTER_INCR(ev) (ev)->ev_count++ 370 371 #else 372 373 #define TCP_CSUM_COUNTER_INCR(ev) /* nothing */ 374 375 #endif /* TCP_CSUM_COUNTERS */ 376 377 #ifdef TCP_REASS_COUNTERS 378 #include <sys/device.h> 379 380 extern struct evcnt tcp_reass_; 381 extern struct evcnt tcp_reass_empty; 382 extern struct evcnt tcp_reass_iteration[8]; 383 extern struct evcnt tcp_reass_prependfirst; 384 extern struct evcnt tcp_reass_prepend; 385 extern struct evcnt tcp_reass_insert; 386 extern struct evcnt tcp_reass_inserttail; 387 extern struct evcnt tcp_reass_append; 388 extern struct evcnt tcp_reass_appendtail; 389 extern struct evcnt tcp_reass_overlaptail; 390 extern struct evcnt tcp_reass_overlapfront; 391 extern struct evcnt tcp_reass_segdup; 392 extern struct evcnt tcp_reass_fragdup; 393 394 #define TCP_REASS_COUNTER_INCR(ev) (ev)->ev_count++ 395 396 #else 397 398 #define TCP_REASS_COUNTER_INCR(ev) /* nothing */ 399 400 #endif /* TCP_REASS_COUNTERS */ 401 402 static int tcp_reass(struct tcpcb *, const struct tcphdr *, struct mbuf *, 403 int); 404 405 static void tcp4_log_refused(const struct ip *, const struct tcphdr *); 406 #ifdef INET6 407 static void tcp6_log_refused(const struct ip6_hdr *, const struct tcphdr *); 408 #endif 409 410 #if defined(MBUFTRACE) 411 struct mowner tcp_reass_mowner = MOWNER_INIT("tcp", "reass"); 412 #endif /* defined(MBUFTRACE) */ 413 414 static struct pool tcpipqent_pool; 415 416 void 417 tcpipqent_init(void) 418 { 419 420 pool_init(&tcpipqent_pool, sizeof(struct ipqent), 0, 0, 0, "tcpipqepl", 421 NULL, IPL_VM); 422 } 423 424 struct ipqent * 425 tcpipqent_alloc(void) 426 { 427 struct ipqent *ipqe; 428 int s; 429 430 s = splvm(); 431 ipqe = pool_get(&tcpipqent_pool, PR_NOWAIT); 432 splx(s); 433 434 return ipqe; 435 } 436 437 void 438 tcpipqent_free(struct ipqent *ipqe) 439 { 440 int s; 441 442 s = splvm(); 443 pool_put(&tcpipqent_pool, ipqe); 444 splx(s); 445 } 446 447 /* 448 * Insert segment ti into reassembly queue of tcp with 449 * control block tp. Return TH_FIN if reassembly now includes 450 * a segment with FIN. 451 */ 452 static int 453 tcp_reass(struct tcpcb *tp, const struct tcphdr *th, struct mbuf *m, int tlen) 454 { 455 struct ipqent *p, *q, *nq, *tiqe = NULL; 456 struct socket *so = NULL; 457 int pkt_flags; 458 tcp_seq pkt_seq; 459 unsigned pkt_len; 460 u_long rcvpartdupbyte = 0; 461 u_long rcvoobyte; 462 #ifdef TCP_REASS_COUNTERS 463 u_int count = 0; 464 #endif 465 net_stat_ref_t tcps; 466 467 so = tp->t_inpcb->inp_socket; 468 469 TCP_REASS_LOCK_CHECK(tp); 470 471 /* 472 * Call with th==NULL after become established to 473 * force pre-ESTABLISHED data up to user socket. 474 */ 475 if (th == NULL) 476 goto present; 477 478 m_claimm(m, &tcp_reass_mowner); 479 480 rcvoobyte = tlen; 481 /* 482 * Copy these to local variables because the TCP header gets munged 483 * while we are collapsing mbufs. 484 */ 485 pkt_seq = th->th_seq; 486 pkt_len = tlen; 487 pkt_flags = th->th_flags; 488 489 TCP_REASS_COUNTER_INCR(&tcp_reass_); 490 491 if ((p = TAILQ_LAST(&tp->segq, ipqehead)) != NULL) { 492 /* 493 * When we miss a packet, the vast majority of time we get 494 * packets that follow it in order. So optimize for that. 495 */ 496 if (pkt_seq == p->ipqe_seq + p->ipqe_len) { 497 p->ipqe_len += pkt_len; 498 p->ipqe_flags |= pkt_flags; 499 m_cat(p->ipqe_m, m); 500 m = NULL; 501 tiqe = p; 502 TAILQ_REMOVE(&tp->timeq, p, ipqe_timeq); 503 TCP_REASS_COUNTER_INCR(&tcp_reass_appendtail); 504 goto skip_replacement; 505 } 506 /* 507 * While we're here, if the pkt is completely beyond 508 * anything we have, just insert it at the tail. 509 */ 510 if (SEQ_GT(pkt_seq, p->ipqe_seq + p->ipqe_len)) { 511 TCP_REASS_COUNTER_INCR(&tcp_reass_inserttail); 512 goto insert_it; 513 } 514 } 515 516 q = TAILQ_FIRST(&tp->segq); 517 518 if (q != NULL) { 519 /* 520 * If this segment immediately precedes the first out-of-order 521 * block, simply slap the segment in front of it and (mostly) 522 * skip the complicated logic. 523 */ 524 if (pkt_seq + pkt_len == q->ipqe_seq) { 525 q->ipqe_seq = pkt_seq; 526 q->ipqe_len += pkt_len; 527 q->ipqe_flags |= pkt_flags; 528 m_cat(m, q->ipqe_m); 529 q->ipqe_m = m; 530 tiqe = q; 531 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 532 TCP_REASS_COUNTER_INCR(&tcp_reass_prependfirst); 533 goto skip_replacement; 534 } 535 } else { 536 TCP_REASS_COUNTER_INCR(&tcp_reass_empty); 537 } 538 539 /* 540 * Find a segment which begins after this one does. 541 */ 542 for (p = NULL; q != NULL; q = nq) { 543 nq = TAILQ_NEXT(q, ipqe_q); 544 #ifdef TCP_REASS_COUNTERS 545 count++; 546 #endif 547 548 /* 549 * If the received segment is just right after this 550 * fragment, merge the two together and then check 551 * for further overlaps. 552 */ 553 if (q->ipqe_seq + q->ipqe_len == pkt_seq) { 554 pkt_len += q->ipqe_len; 555 pkt_flags |= q->ipqe_flags; 556 pkt_seq = q->ipqe_seq; 557 m_cat(q->ipqe_m, m); 558 m = q->ipqe_m; 559 TCP_REASS_COUNTER_INCR(&tcp_reass_append); 560 goto free_ipqe; 561 } 562 563 /* 564 * If the received segment is completely past this 565 * fragment, we need to go to the next fragment. 566 */ 567 if (SEQ_LT(q->ipqe_seq + q->ipqe_len, pkt_seq)) { 568 p = q; 569 continue; 570 } 571 572 /* 573 * If the fragment is past the received segment, 574 * it (or any following) can't be concatenated. 575 */ 576 if (SEQ_GT(q->ipqe_seq, pkt_seq + pkt_len)) { 577 TCP_REASS_COUNTER_INCR(&tcp_reass_insert); 578 break; 579 } 580 581 /* 582 * We've received all the data in this segment before. 583 * Mark it as a duplicate and return. 584 */ 585 if (SEQ_LEQ(q->ipqe_seq, pkt_seq) && 586 SEQ_GEQ(q->ipqe_seq + q->ipqe_len, pkt_seq + pkt_len)) { 587 tcps = TCP_STAT_GETREF(); 588 _NET_STATINC_REF(tcps, TCP_STAT_RCVDUPPACK); 589 _NET_STATADD_REF(tcps, TCP_STAT_RCVDUPBYTE, pkt_len); 590 TCP_STAT_PUTREF(); 591 tcp_new_dsack(tp, pkt_seq, pkt_len); 592 m_freem(m); 593 if (tiqe != NULL) { 594 tcpipqent_free(tiqe); 595 } 596 TCP_REASS_COUNTER_INCR(&tcp_reass_segdup); 597 goto out; 598 } 599 600 /* 601 * Received segment completely overlaps this fragment 602 * so we drop the fragment (this keeps the temporal 603 * ordering of segments correct). 604 */ 605 if (SEQ_GEQ(q->ipqe_seq, pkt_seq) && 606 SEQ_LEQ(q->ipqe_seq + q->ipqe_len, pkt_seq + pkt_len)) { 607 rcvpartdupbyte += q->ipqe_len; 608 m_freem(q->ipqe_m); 609 TCP_REASS_COUNTER_INCR(&tcp_reass_fragdup); 610 goto free_ipqe; 611 } 612 613 /* 614 * Received segment extends past the end of the fragment. 615 * Drop the overlapping bytes, merge the fragment and 616 * segment, and treat as a longer received packet. 617 */ 618 if (SEQ_LT(q->ipqe_seq, pkt_seq) && 619 SEQ_GT(q->ipqe_seq + q->ipqe_len, pkt_seq)) { 620 int overlap = q->ipqe_seq + q->ipqe_len - pkt_seq; 621 m_adj(m, overlap); 622 rcvpartdupbyte += overlap; 623 m_cat(q->ipqe_m, m); 624 m = q->ipqe_m; 625 pkt_seq = q->ipqe_seq; 626 pkt_len += q->ipqe_len - overlap; 627 rcvoobyte -= overlap; 628 TCP_REASS_COUNTER_INCR(&tcp_reass_overlaptail); 629 goto free_ipqe; 630 } 631 632 /* 633 * Received segment extends past the front of the fragment. 634 * Drop the overlapping bytes on the received packet. The 635 * packet will then be concatenated with this fragment a 636 * bit later. 637 */ 638 if (SEQ_GT(q->ipqe_seq, pkt_seq) && 639 SEQ_LT(q->ipqe_seq, pkt_seq + pkt_len)) { 640 int overlap = pkt_seq + pkt_len - q->ipqe_seq; 641 m_adj(m, -overlap); 642 pkt_len -= overlap; 643 rcvpartdupbyte += overlap; 644 TCP_REASS_COUNTER_INCR(&tcp_reass_overlapfront); 645 rcvoobyte -= overlap; 646 } 647 648 /* 649 * If the received segment immediately precedes this 650 * fragment then tack the fragment onto this segment 651 * and reinsert the data. 652 */ 653 if (q->ipqe_seq == pkt_seq + pkt_len) { 654 pkt_len += q->ipqe_len; 655 pkt_flags |= q->ipqe_flags; 656 m_cat(m, q->ipqe_m); 657 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 658 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 659 tp->t_segqlen--; 660 KASSERT(tp->t_segqlen >= 0); 661 KASSERT(tp->t_segqlen != 0 || 662 (TAILQ_EMPTY(&tp->segq) && 663 TAILQ_EMPTY(&tp->timeq))); 664 if (tiqe == NULL) { 665 tiqe = q; 666 } else { 667 tcpipqent_free(q); 668 } 669 TCP_REASS_COUNTER_INCR(&tcp_reass_prepend); 670 break; 671 } 672 673 /* 674 * If the fragment is before the segment, remember it. 675 * When this loop is terminated, p will contain the 676 * pointer to the fragment that is right before the 677 * received segment. 678 */ 679 if (SEQ_LEQ(q->ipqe_seq, pkt_seq)) 680 p = q; 681 682 continue; 683 684 /* 685 * This is a common operation. It also will allow 686 * to save doing a malloc/free in most instances. 687 */ 688 free_ipqe: 689 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 690 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 691 tp->t_segqlen--; 692 KASSERT(tp->t_segqlen >= 0); 693 KASSERT(tp->t_segqlen != 0 || 694 (TAILQ_EMPTY(&tp->segq) && TAILQ_EMPTY(&tp->timeq))); 695 if (tiqe == NULL) { 696 tiqe = q; 697 } else { 698 tcpipqent_free(q); 699 } 700 } 701 702 #ifdef TCP_REASS_COUNTERS 703 if (count > 7) 704 TCP_REASS_COUNTER_INCR(&tcp_reass_iteration[0]); 705 else if (count > 0) 706 TCP_REASS_COUNTER_INCR(&tcp_reass_iteration[count]); 707 #endif 708 709 insert_it: 710 /* 711 * Allocate a new queue entry (block) since the received segment 712 * did not collapse onto any other out-of-order block. If it had 713 * collapsed, tiqe would not be NULL and we would be reusing it. 714 * 715 * If the allocation fails, drop the packet. 716 */ 717 if (tiqe == NULL) { 718 tiqe = tcpipqent_alloc(); 719 if (tiqe == NULL) { 720 TCP_STATINC(TCP_STAT_RCVMEMDROP); 721 m_freem(m); 722 goto out; 723 } 724 } 725 726 /* 727 * Update the counters. 728 */ 729 tp->t_rcvoopack++; 730 tcps = TCP_STAT_GETREF(); 731 _NET_STATINC_REF(tcps, TCP_STAT_RCVOOPACK); 732 _NET_STATADD_REF(tcps, TCP_STAT_RCVOOBYTE, rcvoobyte); 733 if (rcvpartdupbyte) { 734 _NET_STATINC_REF(tcps, TCP_STAT_RCVPARTDUPPACK); 735 _NET_STATADD_REF(tcps, TCP_STAT_RCVPARTDUPBYTE, 736 rcvpartdupbyte); 737 } 738 TCP_STAT_PUTREF(); 739 740 /* 741 * Insert the new fragment queue entry into both queues. 742 */ 743 tiqe->ipqe_m = m; 744 tiqe->ipqe_seq = pkt_seq; 745 tiqe->ipqe_len = pkt_len; 746 tiqe->ipqe_flags = pkt_flags; 747 if (p == NULL) { 748 TAILQ_INSERT_HEAD(&tp->segq, tiqe, ipqe_q); 749 } else { 750 TAILQ_INSERT_AFTER(&tp->segq, p, tiqe, ipqe_q); 751 } 752 tp->t_segqlen++; 753 754 skip_replacement: 755 TAILQ_INSERT_HEAD(&tp->timeq, tiqe, ipqe_timeq); 756 757 present: 758 /* 759 * Present data to user, advancing rcv_nxt through 760 * completed sequence space. 761 */ 762 if (TCPS_HAVEESTABLISHED(tp->t_state) == 0) 763 goto out; 764 q = TAILQ_FIRST(&tp->segq); 765 if (q == NULL || q->ipqe_seq != tp->rcv_nxt) 766 goto out; 767 if (tp->t_state == TCPS_SYN_RECEIVED && q->ipqe_len) 768 goto out; 769 770 tp->rcv_nxt += q->ipqe_len; 771 pkt_flags = q->ipqe_flags & TH_FIN; 772 nd_hint(tp); 773 774 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 775 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 776 tp->t_segqlen--; 777 KASSERT(tp->t_segqlen >= 0); 778 KASSERT(tp->t_segqlen != 0 || 779 (TAILQ_EMPTY(&tp->segq) && TAILQ_EMPTY(&tp->timeq))); 780 if (so->so_state & SS_CANTRCVMORE) 781 m_freem(q->ipqe_m); 782 else 783 sbappendstream(&so->so_rcv, q->ipqe_m); 784 tcpipqent_free(q); 785 TCP_REASS_UNLOCK(tp); 786 sorwakeup(so); 787 return pkt_flags; 788 789 out: 790 TCP_REASS_UNLOCK(tp); 791 return 0; 792 } 793 794 #ifdef INET6 795 int 796 tcp6_input(struct mbuf **mp, int *offp, int proto) 797 { 798 struct mbuf *m = *mp; 799 800 /* 801 * draft-itojun-ipv6-tcp-to-anycast 802 * better place to put this in? 803 */ 804 if (m->m_flags & M_ANYCAST6) { 805 struct ip6_hdr *ip6; 806 if (m->m_len < sizeof(struct ip6_hdr)) { 807 if ((m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) { 808 TCP_STATINC(TCP_STAT_RCVSHORT); 809 return IPPROTO_DONE; 810 } 811 } 812 ip6 = mtod(m, struct ip6_hdr *); 813 icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR, 814 (char *)&ip6->ip6_dst - (char *)ip6); 815 return IPPROTO_DONE; 816 } 817 818 tcp_input(m, *offp, proto); 819 return IPPROTO_DONE; 820 } 821 #endif 822 823 static void 824 tcp4_log_refused(const struct ip *ip, const struct tcphdr *th) 825 { 826 char src[INET_ADDRSTRLEN]; 827 char dst[INET_ADDRSTRLEN]; 828 829 if (ip) { 830 in_print(src, sizeof(src), &ip->ip_src); 831 in_print(dst, sizeof(dst), &ip->ip_dst); 832 } else { 833 strlcpy(src, "(unknown)", sizeof(src)); 834 strlcpy(dst, "(unknown)", sizeof(dst)); 835 } 836 log(LOG_INFO, 837 "Connection attempt to TCP %s:%d from %s:%d\n", 838 dst, ntohs(th->th_dport), 839 src, ntohs(th->th_sport)); 840 } 841 842 #ifdef INET6 843 static void 844 tcp6_log_refused(const struct ip6_hdr *ip6, const struct tcphdr *th) 845 { 846 char src[INET6_ADDRSTRLEN]; 847 char dst[INET6_ADDRSTRLEN]; 848 849 if (ip6) { 850 in6_print(src, sizeof(src), &ip6->ip6_src); 851 in6_print(dst, sizeof(dst), &ip6->ip6_dst); 852 } else { 853 strlcpy(src, "(unknown v6)", sizeof(src)); 854 strlcpy(dst, "(unknown v6)", sizeof(dst)); 855 } 856 log(LOG_INFO, 857 "Connection attempt to TCP [%s]:%d from [%s]:%d\n", 858 dst, ntohs(th->th_dport), 859 src, ntohs(th->th_sport)); 860 } 861 #endif 862 863 /* 864 * Checksum extended TCP header and data. 865 */ 866 int 867 tcp_input_checksum(int af, struct mbuf *m, const struct tcphdr *th, 868 int toff, int off, int tlen) 869 { 870 struct ifnet *rcvif; 871 int s; 872 873 /* 874 * XXX it's better to record and check if this mbuf is 875 * already checked. 876 */ 877 878 rcvif = m_get_rcvif(m, &s); 879 if (__predict_false(rcvif == NULL)) 880 goto badcsum; /* XXX */ 881 882 switch (af) { 883 case AF_INET: 884 switch (m->m_pkthdr.csum_flags & 885 ((rcvif->if_csum_flags_rx & M_CSUM_TCPv4) | 886 M_CSUM_TCP_UDP_BAD | M_CSUM_DATA)) { 887 case M_CSUM_TCPv4|M_CSUM_TCP_UDP_BAD: 888 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_bad); 889 goto badcsum; 890 891 case M_CSUM_TCPv4|M_CSUM_DATA: { 892 u_int32_t hw_csum = m->m_pkthdr.csum_data; 893 894 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_data); 895 if (m->m_pkthdr.csum_flags & M_CSUM_NO_PSEUDOHDR) { 896 const struct ip *ip = 897 mtod(m, const struct ip *); 898 899 hw_csum = in_cksum_phdr(ip->ip_src.s_addr, 900 ip->ip_dst.s_addr, 901 htons(hw_csum + tlen + off + IPPROTO_TCP)); 902 } 903 if ((hw_csum ^ 0xffff) != 0) 904 goto badcsum; 905 break; 906 } 907 908 case M_CSUM_TCPv4: 909 /* Checksum was okay. */ 910 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_ok); 911 break; 912 913 default: 914 /* 915 * Must compute it ourselves. Maybe skip checksum 916 * on loopback interfaces. 917 */ 918 if (__predict_true(!(rcvif->if_flags & IFF_LOOPBACK) || 919 tcp_do_loopback_cksum)) { 920 TCP_CSUM_COUNTER_INCR(&tcp_swcsum); 921 if (in4_cksum(m, IPPROTO_TCP, toff, 922 tlen + off) != 0) 923 goto badcsum; 924 } 925 break; 926 } 927 break; 928 929 #ifdef INET6 930 case AF_INET6: 931 switch (m->m_pkthdr.csum_flags & 932 ((rcvif->if_csum_flags_rx & M_CSUM_TCPv6) | 933 M_CSUM_TCP_UDP_BAD | M_CSUM_DATA)) { 934 case M_CSUM_TCPv6|M_CSUM_TCP_UDP_BAD: 935 TCP_CSUM_COUNTER_INCR(&tcp6_hwcsum_bad); 936 goto badcsum; 937 938 #if 0 /* notyet */ 939 case M_CSUM_TCPv6|M_CSUM_DATA: 940 #endif 941 942 case M_CSUM_TCPv6: 943 /* Checksum was okay. */ 944 TCP_CSUM_COUNTER_INCR(&tcp6_hwcsum_ok); 945 break; 946 947 default: 948 /* 949 * Must compute it ourselves. Maybe skip checksum 950 * on loopback interfaces. 951 */ 952 if (__predict_true((m->m_flags & M_LOOP) == 0 || 953 tcp_do_loopback_cksum)) { 954 TCP_CSUM_COUNTER_INCR(&tcp6_swcsum); 955 if (in6_cksum(m, IPPROTO_TCP, toff, 956 tlen + off) != 0) 957 goto badcsum; 958 } 959 } 960 break; 961 #endif /* INET6 */ 962 } 963 m_put_rcvif(rcvif, &s); 964 965 return 0; 966 967 badcsum: 968 m_put_rcvif(rcvif, &s); 969 TCP_STATINC(TCP_STAT_RCVBADSUM); 970 return -1; 971 } 972 973 /* 974 * When a packet arrives addressed to a vestigial tcpbp, we 975 * nevertheless have to respond to it per the spec. 976 * 977 * This code is duplicated from the one in tcp_input(). 978 */ 979 static void tcp_vtw_input(struct tcphdr *th, vestigial_inpcb_t *vp, 980 struct mbuf *m, int tlen) 981 { 982 int tiflags; 983 int todrop; 984 uint32_t t_flags = 0; 985 net_stat_ref_t tcps; 986 987 tiflags = th->th_flags; 988 todrop = vp->rcv_nxt - th->th_seq; 989 990 if (todrop > 0) { 991 if (tiflags & TH_SYN) { 992 tiflags &= ~TH_SYN; 993 th->th_seq++; 994 tcp_urp_drop(th, 1, &tiflags); 995 todrop--; 996 } 997 if (todrop > tlen || 998 (todrop == tlen && (tiflags & TH_FIN) == 0)) { 999 /* 1000 * Any valid FIN or RST must be to the left of the 1001 * window. At this point the FIN or RST must be a 1002 * duplicate or out of sequence; drop it. 1003 */ 1004 if (tiflags & TH_RST) 1005 goto drop; 1006 tiflags &= ~(TH_FIN|TH_RST); 1007 1008 /* 1009 * Send an ACK to resynchronize and drop any data. 1010 * But keep on processing for RST or ACK. 1011 */ 1012 t_flags |= TF_ACKNOW; 1013 todrop = tlen; 1014 tcps = TCP_STAT_GETREF(); 1015 _NET_STATINC_REF(tcps, TCP_STAT_RCVDUPPACK); 1016 _NET_STATADD_REF(tcps, TCP_STAT_RCVDUPBYTE, todrop); 1017 TCP_STAT_PUTREF(); 1018 } else if ((tiflags & TH_RST) && 1019 th->th_seq != vp->rcv_nxt) { 1020 /* 1021 * Test for reset before adjusting the sequence 1022 * number for overlapping data. 1023 */ 1024 goto dropafterack_ratelim; 1025 } else { 1026 tcps = TCP_STAT_GETREF(); 1027 _NET_STATINC_REF(tcps, TCP_STAT_RCVPARTDUPPACK); 1028 _NET_STATADD_REF(tcps, TCP_STAT_RCVPARTDUPBYTE, 1029 todrop); 1030 TCP_STAT_PUTREF(); 1031 } 1032 1033 // tcp_new_dsack(tp, th->th_seq, todrop); 1034 // hdroptlen += todrop; /*drop from head afterwards*/ 1035 1036 th->th_seq += todrop; 1037 tlen -= todrop; 1038 tcp_urp_drop(th, todrop, &tiflags); 1039 } 1040 1041 /* 1042 * If new data are received on a connection after the 1043 * user processes are gone, then RST the other end. 1044 */ 1045 if (tlen) { 1046 TCP_STATINC(TCP_STAT_RCVAFTERCLOSE); 1047 goto dropwithreset; 1048 } 1049 1050 /* 1051 * If segment ends after window, drop trailing data 1052 * (and PUSH and FIN); if nothing left, just ACK. 1053 */ 1054 todrop = (th->th_seq + tlen) - (vp->rcv_nxt + vp->rcv_wnd); 1055 1056 if (todrop > 0) { 1057 TCP_STATINC(TCP_STAT_RCVPACKAFTERWIN); 1058 if (todrop >= tlen) { 1059 /* 1060 * The segment actually starts after the window. 1061 * th->th_seq + tlen - vp->rcv_nxt - vp->rcv_wnd >= tlen 1062 * th->th_seq - vp->rcv_nxt - vp->rcv_wnd >= 0 1063 * th->th_seq >= vp->rcv_nxt + vp->rcv_wnd 1064 */ 1065 TCP_STATADD(TCP_STAT_RCVBYTEAFTERWIN, tlen); 1066 1067 /* 1068 * If a new connection request is received 1069 * while in TIME_WAIT, drop the old connection 1070 * and start over if the sequence numbers 1071 * are above the previous ones. 1072 */ 1073 if ((tiflags & TH_SYN) && 1074 SEQ_GT(th->th_seq, vp->rcv_nxt)) { 1075 /* 1076 * We only support this in the !NOFDREF case, which 1077 * is to say: not here. 1078 */ 1079 goto dropwithreset; 1080 } 1081 1082 /* 1083 * If window is closed can only take segments at 1084 * window edge, and have to drop data and PUSH from 1085 * incoming segments. Continue processing, but 1086 * remember to ack. Otherwise, drop segment 1087 * and (if not RST) ack. 1088 */ 1089 if (vp->rcv_wnd == 0 && th->th_seq == vp->rcv_nxt) { 1090 t_flags |= TF_ACKNOW; 1091 TCP_STATINC(TCP_STAT_RCVWINPROBE); 1092 } else { 1093 goto dropafterack; 1094 } 1095 } else { 1096 TCP_STATADD(TCP_STAT_RCVBYTEAFTERWIN, todrop); 1097 } 1098 m_adj(m, -todrop); 1099 tlen -= todrop; 1100 tiflags &= ~(TH_PUSH|TH_FIN); 1101 } 1102 1103 if (tiflags & TH_RST) { 1104 if (th->th_seq != vp->rcv_nxt) 1105 goto dropafterack_ratelim; 1106 1107 vtw_del(vp->ctl, vp->vtw); 1108 goto drop; 1109 } 1110 1111 /* 1112 * If the ACK bit is off we drop the segment and return. 1113 */ 1114 if ((tiflags & TH_ACK) == 0) { 1115 if (t_flags & TF_ACKNOW) 1116 goto dropafterack; 1117 goto drop; 1118 } 1119 1120 /* 1121 * In TIME_WAIT state the only thing that should arrive 1122 * is a retransmission of the remote FIN. Acknowledge 1123 * it and restart the finack timer. 1124 */ 1125 vtw_restart(vp); 1126 goto dropafterack; 1127 1128 dropafterack: 1129 /* 1130 * Generate an ACK dropping incoming segment if it occupies 1131 * sequence space, where the ACK reflects our state. 1132 */ 1133 if (tiflags & TH_RST) 1134 goto drop; 1135 goto dropafterack2; 1136 1137 dropafterack_ratelim: 1138 /* 1139 * We may want to rate-limit ACKs against SYN/RST attack. 1140 */ 1141 if (ppsratecheck(&tcp_ackdrop_ppslim_last, &tcp_ackdrop_ppslim_count, 1142 tcp_ackdrop_ppslim) == 0) { 1143 /* XXX stat */ 1144 goto drop; 1145 } 1146 /* ...fall into dropafterack2... */ 1147 1148 dropafterack2: 1149 (void)tcp_respond(0, m, m, th, th->th_seq + tlen, th->th_ack, TH_ACK); 1150 return; 1151 1152 dropwithreset: 1153 /* 1154 * Generate a RST, dropping incoming segment. 1155 * Make ACK acceptable to originator of segment. 1156 */ 1157 if (tiflags & TH_RST) 1158 goto drop; 1159 1160 if (tiflags & TH_ACK) { 1161 tcp_respond(0, m, m, th, (tcp_seq)0, th->th_ack, TH_RST); 1162 } else { 1163 if (tiflags & TH_SYN) 1164 ++tlen; 1165 (void)tcp_respond(0, m, m, th, th->th_seq + tlen, (tcp_seq)0, 1166 TH_RST|TH_ACK); 1167 } 1168 return; 1169 drop: 1170 m_freem(m); 1171 } 1172 1173 /* 1174 * TCP input routine, follows pages 65-76 of RFC 793 very closely. 1175 */ 1176 void 1177 tcp_input(struct mbuf *m, int off, int proto) 1178 { 1179 struct tcphdr *th; 1180 struct ip *ip; 1181 struct inpcb *inp; 1182 #ifdef INET6 1183 struct ip6_hdr *ip6; 1184 #endif 1185 u_int8_t *optp = NULL; 1186 int optlen = 0; 1187 int len, tlen, hdroptlen = 0; 1188 struct tcpcb *tp = NULL; 1189 int tiflags; 1190 struct socket *so = NULL; 1191 int todrop, acked, ourfinisacked, needoutput = 0; 1192 bool dupseg; 1193 #ifdef TCP_DEBUG 1194 short ostate = 0; 1195 #endif 1196 u_long tiwin; 1197 struct tcp_opt_info opti; 1198 int thlen, iphlen; 1199 int af; /* af on the wire */ 1200 struct mbuf *tcp_saveti = NULL; 1201 uint32_t ts_rtt; 1202 uint8_t iptos; 1203 net_stat_ref_t tcps; 1204 vestigial_inpcb_t vestige; 1205 1206 vestige.valid = 0; 1207 1208 MCLAIM(m, &tcp_rx_mowner); 1209 1210 TCP_STATINC(TCP_STAT_RCVTOTAL); 1211 1212 memset(&opti, 0, sizeof(opti)); 1213 opti.ts_present = 0; 1214 opti.maxseg = 0; 1215 1216 /* 1217 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN. 1218 * 1219 * TCP is, by definition, unicast, so we reject all 1220 * multicast outright. 1221 * 1222 * Note, there are additional src/dst address checks in 1223 * the AF-specific code below. 1224 */ 1225 if (m->m_flags & (M_BCAST|M_MCAST)) { 1226 /* XXX stat */ 1227 goto drop; 1228 } 1229 #ifdef INET6 1230 if (m->m_flags & M_ANYCAST6) { 1231 /* XXX stat */ 1232 goto drop; 1233 } 1234 #endif 1235 1236 M_REGION_GET(th, struct tcphdr *, m, off, sizeof(struct tcphdr)); 1237 if (th == NULL) { 1238 TCP_STATINC(TCP_STAT_RCVSHORT); 1239 return; 1240 } 1241 1242 /* 1243 * Enforce alignment requirements that are violated in 1244 * some cases, see kern/50766 for details. 1245 */ 1246 if (ACCESSIBLE_POINTER(th, struct tcphdr) == 0) { 1247 m = m_copyup(m, off + sizeof(struct tcphdr), 0); 1248 if (m == NULL) { 1249 TCP_STATINC(TCP_STAT_RCVSHORT); 1250 return; 1251 } 1252 th = (struct tcphdr *)(mtod(m, char *) + off); 1253 } 1254 KASSERT(ACCESSIBLE_POINTER(th, struct tcphdr)); 1255 1256 /* 1257 * Get IP and TCP header. 1258 * Note: IP leaves IP header in first mbuf. 1259 */ 1260 ip = mtod(m, struct ip *); 1261 #ifdef INET6 1262 ip6 = mtod(m, struct ip6_hdr *); 1263 #endif 1264 switch (ip->ip_v) { 1265 case 4: 1266 af = AF_INET; 1267 iphlen = sizeof(struct ip); 1268 1269 if (IN_MULTICAST(ip->ip_dst.s_addr) || 1270 in_broadcast(ip->ip_dst, m_get_rcvif_NOMPSAFE(m))) 1271 goto drop; 1272 1273 /* We do the checksum after PCB lookup... */ 1274 len = ntohs(ip->ip_len); 1275 tlen = len - off; 1276 iptos = ip->ip_tos; 1277 break; 1278 #ifdef INET6 1279 case 6: 1280 iphlen = sizeof(struct ip6_hdr); 1281 af = AF_INET6; 1282 1283 /* 1284 * Be proactive about unspecified IPv6 address in source. 1285 * As we use all-zero to indicate unbounded/unconnected pcb, 1286 * unspecified IPv6 address can be used to confuse us. 1287 * 1288 * Note that packets with unspecified IPv6 destination is 1289 * already dropped in ip6_input. 1290 */ 1291 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 1292 /* XXX stat */ 1293 goto drop; 1294 } 1295 1296 /* 1297 * Make sure destination address is not multicast. 1298 * Source address checked in ip6_input(). 1299 */ 1300 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) { 1301 /* XXX stat */ 1302 goto drop; 1303 } 1304 1305 /* We do the checksum after PCB lookup... */ 1306 len = m->m_pkthdr.len; 1307 tlen = len - off; 1308 iptos = (ntohl(ip6->ip6_flow) >> 20) & 0xff; 1309 break; 1310 #endif 1311 default: 1312 m_freem(m); 1313 return; 1314 } 1315 1316 1317 /* 1318 * Check that TCP offset makes sense, pull out TCP options and 1319 * adjust length. 1320 */ 1321 thlen = th->th_off << 2; 1322 if (thlen < sizeof(struct tcphdr) || thlen > tlen) { 1323 TCP_STATINC(TCP_STAT_RCVBADOFF); 1324 goto drop; 1325 } 1326 tlen -= thlen; 1327 1328 if (thlen > sizeof(struct tcphdr)) { 1329 M_REGION_GET(th, struct tcphdr *, m, off, thlen); 1330 if (th == NULL) { 1331 TCP_STATINC(TCP_STAT_RCVSHORT); 1332 return; 1333 } 1334 KASSERT(ACCESSIBLE_POINTER(th, struct tcphdr)); 1335 optlen = thlen - sizeof(struct tcphdr); 1336 optp = ((u_int8_t *)th) + sizeof(struct tcphdr); 1337 1338 /* 1339 * Do quick retrieval of timestamp options. 1340 * 1341 * If timestamp is the only option and it's formatted as 1342 * recommended in RFC 1323 appendix A, we quickly get the 1343 * values now and don't bother calling tcp_dooptions(), 1344 * etc. 1345 */ 1346 if ((optlen == TCPOLEN_TSTAMP_APPA || 1347 (optlen > TCPOLEN_TSTAMP_APPA && 1348 optp[TCPOLEN_TSTAMP_APPA] == TCPOPT_EOL)) && 1349 be32dec(optp) == TCPOPT_TSTAMP_HDR && 1350 (th->th_flags & TH_SYN) == 0) { 1351 opti.ts_present = 1; 1352 opti.ts_val = be32dec(optp + 4); 1353 opti.ts_ecr = be32dec(optp + 8); 1354 optp = NULL; /* we've parsed the options */ 1355 } 1356 } 1357 tiflags = th->th_flags; 1358 1359 /* 1360 * Checksum extended TCP header and data 1361 */ 1362 if (tcp_input_checksum(af, m, th, off, thlen, tlen)) 1363 goto badcsum; 1364 1365 /* 1366 * Locate pcb for segment. 1367 */ 1368 findpcb: 1369 inp = NULL; 1370 switch (af) { 1371 case AF_INET: 1372 inp = inpcb_lookup(&tcbtable, ip->ip_src, th->th_sport, 1373 ip->ip_dst, th->th_dport, &vestige); 1374 if (inp == NULL && !vestige.valid) { 1375 TCP_STATINC(TCP_STAT_PCBHASHMISS); 1376 inp = inpcb_lookup_bound(&tcbtable, ip->ip_dst, 1377 th->th_dport); 1378 } 1379 #ifdef INET6 1380 if (inp == NULL && !vestige.valid) { 1381 struct in6_addr s, d; 1382 1383 /* mapped addr case */ 1384 in6_in_2_v4mapin6(&ip->ip_src, &s); 1385 in6_in_2_v4mapin6(&ip->ip_dst, &d); 1386 inp = in6pcb_lookup(&tcbtable, &s, 1387 th->th_sport, &d, th->th_dport, 0, &vestige); 1388 if (inp == NULL && !vestige.valid) { 1389 TCP_STATINC(TCP_STAT_PCBHASHMISS); 1390 inp = in6pcb_lookup_bound(&tcbtable, &d, 1391 th->th_dport, 0); 1392 } 1393 } 1394 #endif 1395 if (inp == NULL && !vestige.valid) { 1396 TCP_STATINC(TCP_STAT_NOPORT); 1397 if (tcp_log_refused && 1398 (tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) { 1399 tcp4_log_refused(ip, th); 1400 } 1401 tcp_fields_to_host(th); 1402 goto dropwithreset_ratelim; 1403 } 1404 #if defined(IPSEC) 1405 if (ipsec_used) { 1406 if (inp && ipsec_in_reject(m, inp)) 1407 goto drop; 1408 } 1409 #endif /*IPSEC*/ 1410 break; 1411 #ifdef INET6 1412 case AF_INET6: 1413 { 1414 int faith; 1415 1416 #if defined(NFAITH) && NFAITH > 0 1417 faith = faithprefix(&ip6->ip6_dst); 1418 #else 1419 faith = 0; 1420 #endif 1421 inp = in6pcb_lookup(&tcbtable, &ip6->ip6_src, 1422 th->th_sport, &ip6->ip6_dst, th->th_dport, faith, &vestige); 1423 if (inp == NULL && !vestige.valid) { 1424 TCP_STATINC(TCP_STAT_PCBHASHMISS); 1425 inp = in6pcb_lookup_bound(&tcbtable, &ip6->ip6_dst, 1426 th->th_dport, faith); 1427 } 1428 if (inp == NULL && !vestige.valid) { 1429 TCP_STATINC(TCP_STAT_NOPORT); 1430 if (tcp_log_refused && 1431 (tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) { 1432 tcp6_log_refused(ip6, th); 1433 } 1434 tcp_fields_to_host(th); 1435 goto dropwithreset_ratelim; 1436 } 1437 #if defined(IPSEC) 1438 if (ipsec_used && inp && ipsec_in_reject(m, inp)) 1439 goto drop; 1440 #endif 1441 break; 1442 } 1443 #endif 1444 } 1445 1446 tcp_fields_to_host(th); 1447 1448 /* 1449 * If the state is CLOSED (i.e., TCB does not exist) then 1450 * all data in the incoming segment is discarded. 1451 * If the TCB exists but is in CLOSED state, it is embryonic, 1452 * but should either do a listen or a connect soon. 1453 */ 1454 tp = NULL; 1455 so = NULL; 1456 if (inp) { 1457 /* Check the minimum TTL for socket. */ 1458 if (inp->inp_af == AF_INET && ip->ip_ttl < in4p_ip_minttl(inp)) 1459 goto drop; 1460 1461 tp = intotcpcb(inp); 1462 so = inp->inp_socket; 1463 } else if (vestige.valid) { 1464 /* We do not support the resurrection of vtw tcpcps. */ 1465 tcp_vtw_input(th, &vestige, m, tlen); 1466 m = NULL; 1467 goto drop; 1468 } 1469 1470 if (tp == NULL) 1471 goto dropwithreset_ratelim; 1472 if (tp->t_state == TCPS_CLOSED) 1473 goto drop; 1474 1475 KASSERT(so->so_lock == softnet_lock); 1476 KASSERT(solocked(so)); 1477 1478 /* Unscale the window into a 32-bit value. */ 1479 if ((tiflags & TH_SYN) == 0) 1480 tiwin = th->th_win << tp->snd_scale; 1481 else 1482 tiwin = th->th_win; 1483 1484 #ifdef INET6 1485 /* save packet options if user wanted */ 1486 if (inp->inp_af == AF_INET6 && (inp->inp_flags & IN6P_CONTROLOPTS)) { 1487 m_freem(inp->inp_options); 1488 inp->inp_options = NULL; 1489 ip6_savecontrol(inp, &inp->inp_options, ip6, m); 1490 } 1491 #endif 1492 1493 if (so->so_options & SO_DEBUG) { 1494 #ifdef TCP_DEBUG 1495 ostate = tp->t_state; 1496 #endif 1497 1498 tcp_saveti = NULL; 1499 if (iphlen + sizeof(struct tcphdr) > MHLEN) 1500 goto nosave; 1501 1502 if (m->m_len > iphlen && (m->m_flags & M_EXT) == 0) { 1503 tcp_saveti = m_copym(m, 0, iphlen, M_DONTWAIT); 1504 if (tcp_saveti == NULL) 1505 goto nosave; 1506 } else { 1507 MGETHDR(tcp_saveti, M_DONTWAIT, MT_HEADER); 1508 if (tcp_saveti == NULL) 1509 goto nosave; 1510 MCLAIM(m, &tcp_mowner); 1511 tcp_saveti->m_len = iphlen; 1512 m_copydata(m, 0, iphlen, 1513 mtod(tcp_saveti, void *)); 1514 } 1515 1516 if (M_TRAILINGSPACE(tcp_saveti) < sizeof(struct tcphdr)) { 1517 m_freem(tcp_saveti); 1518 tcp_saveti = NULL; 1519 } else { 1520 tcp_saveti->m_len += sizeof(struct tcphdr); 1521 memcpy(mtod(tcp_saveti, char *) + iphlen, th, 1522 sizeof(struct tcphdr)); 1523 } 1524 nosave:; 1525 } 1526 1527 if (so->so_options & SO_ACCEPTCONN) { 1528 union syn_cache_sa src; 1529 union syn_cache_sa dst; 1530 1531 KASSERT(tp->t_state == TCPS_LISTEN); 1532 1533 memset(&src, 0, sizeof(src)); 1534 memset(&dst, 0, sizeof(dst)); 1535 switch (af) { 1536 case AF_INET: 1537 src.sin.sin_len = sizeof(struct sockaddr_in); 1538 src.sin.sin_family = AF_INET; 1539 src.sin.sin_addr = ip->ip_src; 1540 src.sin.sin_port = th->th_sport; 1541 1542 dst.sin.sin_len = sizeof(struct sockaddr_in); 1543 dst.sin.sin_family = AF_INET; 1544 dst.sin.sin_addr = ip->ip_dst; 1545 dst.sin.sin_port = th->th_dport; 1546 break; 1547 #ifdef INET6 1548 case AF_INET6: 1549 src.sin6.sin6_len = sizeof(struct sockaddr_in6); 1550 src.sin6.sin6_family = AF_INET6; 1551 src.sin6.sin6_addr = ip6->ip6_src; 1552 src.sin6.sin6_port = th->th_sport; 1553 1554 dst.sin6.sin6_len = sizeof(struct sockaddr_in6); 1555 dst.sin6.sin6_family = AF_INET6; 1556 dst.sin6.sin6_addr = ip6->ip6_dst; 1557 dst.sin6.sin6_port = th->th_dport; 1558 break; 1559 #endif 1560 } 1561 1562 if ((tiflags & (TH_RST|TH_ACK|TH_SYN)) != TH_SYN) { 1563 if (tiflags & TH_RST) { 1564 syn_cache_reset(&src.sa, &dst.sa, th); 1565 } else if ((tiflags & (TH_ACK|TH_SYN)) == 1566 (TH_ACK|TH_SYN)) { 1567 /* 1568 * Received a SYN,ACK. This should never 1569 * happen while we are in LISTEN. Send an RST. 1570 */ 1571 goto badsyn; 1572 } else if (tiflags & TH_ACK) { 1573 so = syn_cache_get(&src.sa, &dst.sa, th, so, m); 1574 if (so == NULL) { 1575 /* 1576 * We don't have a SYN for this ACK; 1577 * send an RST. 1578 */ 1579 goto badsyn; 1580 } else if (so == (struct socket *)(-1)) { 1581 /* 1582 * We were unable to create the 1583 * connection. If the 3-way handshake 1584 * was completed, and RST has been 1585 * sent to the peer. Since the mbuf 1586 * might be in use for the reply, do 1587 * not free it. 1588 */ 1589 m = NULL; 1590 } else { 1591 /* 1592 * We have created a full-blown 1593 * connection. 1594 */ 1595 inp = sotoinpcb(so); 1596 tp = intotcpcb(inp); 1597 if (tp == NULL) 1598 goto badsyn; /*XXX*/ 1599 tiwin <<= tp->snd_scale; 1600 goto after_listen; 1601 } 1602 } else { 1603 /* 1604 * None of RST, SYN or ACK was set. 1605 * This is an invalid packet for a 1606 * TCB in LISTEN state. Send a RST. 1607 */ 1608 goto badsyn; 1609 } 1610 } else { 1611 /* 1612 * Received a SYN. 1613 */ 1614 1615 #ifdef INET6 1616 /* 1617 * If deprecated address is forbidden, we do 1618 * not accept SYN to deprecated interface 1619 * address to prevent any new inbound 1620 * connection from getting established. 1621 * When we do not accept SYN, we send a TCP 1622 * RST, with deprecated source address (instead 1623 * of dropping it). We compromise it as it is 1624 * much better for peer to send a RST, and 1625 * RST will be the final packet for the 1626 * exchange. 1627 * 1628 * If we do not forbid deprecated addresses, we 1629 * accept the SYN packet. RFC2462 does not 1630 * suggest dropping SYN in this case. 1631 * If we decipher RFC2462 5.5.4, it says like 1632 * this: 1633 * 1. use of deprecated addr with existing 1634 * communication is okay - "SHOULD continue 1635 * to be used" 1636 * 2. use of it with new communication: 1637 * (2a) "SHOULD NOT be used if alternate 1638 * address with sufficient scope is 1639 * available" 1640 * (2b) nothing mentioned otherwise. 1641 * Here we fall into (2b) case as we have no 1642 * choice in our source address selection - we 1643 * must obey the peer. 1644 * 1645 * The wording in RFC2462 is confusing, and 1646 * there are multiple description text for 1647 * deprecated address handling - worse, they 1648 * are not exactly the same. I believe 5.5.4 1649 * is the best one, so we follow 5.5.4. 1650 */ 1651 if (af == AF_INET6 && !ip6_use_deprecated) { 1652 struct in6_ifaddr *ia6; 1653 int s; 1654 struct ifnet *rcvif = m_get_rcvif(m, &s); 1655 if (rcvif == NULL) 1656 goto dropwithreset; /* XXX */ 1657 if ((ia6 = in6ifa_ifpwithaddr(rcvif, 1658 &ip6->ip6_dst)) && 1659 (ia6->ia6_flags & IN6_IFF_DEPRECATED)) { 1660 tp = NULL; 1661 m_put_rcvif(rcvif, &s); 1662 goto dropwithreset; 1663 } 1664 m_put_rcvif(rcvif, &s); 1665 } 1666 #endif 1667 1668 /* 1669 * LISTEN socket received a SYN from itself? This 1670 * can't possibly be valid; drop the packet. 1671 */ 1672 if (th->th_sport == th->th_dport) { 1673 int eq = 0; 1674 1675 switch (af) { 1676 case AF_INET: 1677 eq = in_hosteq(ip->ip_src, ip->ip_dst); 1678 break; 1679 #ifdef INET6 1680 case AF_INET6: 1681 eq = IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, 1682 &ip6->ip6_dst); 1683 break; 1684 #endif 1685 } 1686 if (eq) { 1687 TCP_STATINC(TCP_STAT_BADSYN); 1688 goto drop; 1689 } 1690 } 1691 1692 /* 1693 * SYN looks ok; create compressed TCP 1694 * state for it. 1695 */ 1696 if (so->so_qlen <= so->so_qlimit && 1697 syn_cache_add(&src.sa, &dst.sa, th, off, 1698 so, m, optp, optlen, &opti)) 1699 m = NULL; 1700 } 1701 1702 goto drop; 1703 } 1704 1705 after_listen: 1706 /* 1707 * From here on, we're dealing with !LISTEN. 1708 */ 1709 KASSERT(tp->t_state != TCPS_LISTEN); 1710 1711 /* 1712 * Segment received on connection. 1713 * Reset idle time and keep-alive timer. 1714 */ 1715 tp->t_rcvtime = tcp_now; 1716 if (TCPS_HAVEESTABLISHED(tp->t_state)) 1717 TCP_TIMER_ARM(tp, TCPT_KEEP, tp->t_keepidle); 1718 1719 /* 1720 * Process options. 1721 */ 1722 #ifdef TCP_SIGNATURE 1723 if (optp || (tp->t_flags & TF_SIGNATURE)) 1724 #else 1725 if (optp) 1726 #endif 1727 if (tcp_dooptions(tp, optp, optlen, th, m, off, &opti) < 0) 1728 goto drop; 1729 1730 if (TCP_SACK_ENABLED(tp)) { 1731 tcp_del_sackholes(tp, th); 1732 } 1733 1734 if (TCP_ECN_ALLOWED(tp)) { 1735 if (tiflags & TH_CWR) { 1736 tp->t_flags &= ~TF_ECN_SND_ECE; 1737 } 1738 switch (iptos & IPTOS_ECN_MASK) { 1739 case IPTOS_ECN_CE: 1740 tp->t_flags |= TF_ECN_SND_ECE; 1741 TCP_STATINC(TCP_STAT_ECN_CE); 1742 break; 1743 case IPTOS_ECN_ECT0: 1744 TCP_STATINC(TCP_STAT_ECN_ECT); 1745 break; 1746 case IPTOS_ECN_ECT1: 1747 /* XXX: ignore for now -- rpaulo */ 1748 break; 1749 } 1750 /* 1751 * Congestion experienced. 1752 * Ignore if we are already trying to recover. 1753 */ 1754 if ((tiflags & TH_ECE) && SEQ_GEQ(tp->snd_una, tp->snd_recover)) 1755 tp->t_congctl->cong_exp(tp); 1756 } 1757 1758 if (opti.ts_present && opti.ts_ecr) { 1759 /* 1760 * Calculate the RTT from the returned time stamp and the 1761 * connection's time base. If the time stamp is later than 1762 * the current time, or is extremely old, fall back to non-1323 1763 * RTT calculation. Since ts_rtt is unsigned, we can test both 1764 * at the same time. 1765 * 1766 * Note that ts_rtt is in units of slow ticks (500 1767 * ms). Since most earthbound RTTs are < 500 ms, 1768 * observed values will have large quantization noise. 1769 * Our smoothed RTT is then the fraction of observed 1770 * samples that are 1 tick instead of 0 (times 500 1771 * ms). 1772 * 1773 * ts_rtt is increased by 1 to denote a valid sample, 1774 * with 0 indicating an invalid measurement. This 1775 * extra 1 must be removed when ts_rtt is used, or 1776 * else an erroneous extra 500 ms will result. 1777 */ 1778 ts_rtt = TCP_TIMESTAMP(tp) - opti.ts_ecr + 1; 1779 if (ts_rtt > TCP_PAWS_IDLE) 1780 ts_rtt = 0; 1781 } else { 1782 ts_rtt = 0; 1783 } 1784 1785 /* 1786 * Fast path: check for the two common cases of a uni-directional 1787 * data transfer. If: 1788 * o We are in the ESTABLISHED state, and 1789 * o The packet has no control flags, and 1790 * o The packet is in-sequence, and 1791 * o The window didn't change, and 1792 * o We are not retransmitting 1793 * It's a candidate. 1794 * 1795 * If the length (tlen) is zero and the ack moved forward, we're 1796 * the sender side of the transfer. Just free the data acked and 1797 * wake any higher level process that was blocked waiting for 1798 * space. 1799 * 1800 * If the length is non-zero and the ack didn't move, we're the 1801 * receiver side. If we're getting packets in-order (the reassembly 1802 * queue is empty), add the data to the socket buffer and note 1803 * that we need a delayed ack. 1804 */ 1805 if (tp->t_state == TCPS_ESTABLISHED && 1806 (tiflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ECE|TH_CWR|TH_ACK)) 1807 == TH_ACK && 1808 (!opti.ts_present || TSTMP_GEQ(opti.ts_val, tp->ts_recent)) && 1809 th->th_seq == tp->rcv_nxt && 1810 tiwin && tiwin == tp->snd_wnd && 1811 tp->snd_nxt == tp->snd_max) { 1812 1813 /* 1814 * If last ACK falls within this segment's sequence numbers, 1815 * record the timestamp. 1816 * NOTE that the test is modified according to the latest 1817 * proposal of the tcplw (at) cray.com list (Braden 1993/04/26). 1818 * 1819 * note that we already know 1820 * TSTMP_GEQ(opti.ts_val, tp->ts_recent) 1821 */ 1822 if (opti.ts_present && SEQ_LEQ(th->th_seq, tp->last_ack_sent)) { 1823 tp->ts_recent_age = tcp_now; 1824 tp->ts_recent = opti.ts_val; 1825 } 1826 1827 if (tlen == 0) { 1828 /* Ack prediction. */ 1829 if (SEQ_GT(th->th_ack, tp->snd_una) && 1830 SEQ_LEQ(th->th_ack, tp->snd_max) && 1831 tp->snd_cwnd >= tp->snd_wnd && 1832 tp->t_partialacks < 0) { 1833 /* 1834 * this is a pure ack for outstanding data. 1835 */ 1836 if (ts_rtt) 1837 tcp_xmit_timer(tp, ts_rtt - 1); 1838 else if (tp->t_rtttime && 1839 SEQ_GT(th->th_ack, tp->t_rtseq)) 1840 tcp_xmit_timer(tp, 1841 tcp_now - tp->t_rtttime); 1842 acked = th->th_ack - tp->snd_una; 1843 tcps = TCP_STAT_GETREF(); 1844 _NET_STATINC_REF(tcps, TCP_STAT_PREDACK); 1845 _NET_STATINC_REF(tcps, TCP_STAT_RCVACKPACK); 1846 _NET_STATADD_REF(tcps, TCP_STAT_RCVACKBYTE, 1847 acked); 1848 TCP_STAT_PUTREF(); 1849 nd_hint(tp); 1850 1851 if (acked > (tp->t_lastoff - tp->t_inoff)) 1852 tp->t_lastm = NULL; 1853 sbdrop(&so->so_snd, acked); 1854 tp->t_lastoff -= acked; 1855 1856 icmp_check(tp, th, acked); 1857 1858 tp->snd_una = th->th_ack; 1859 tp->snd_fack = tp->snd_una; 1860 if (SEQ_LT(tp->snd_high, tp->snd_una)) 1861 tp->snd_high = tp->snd_una; 1862 /* 1863 * drag snd_wl2 along so only newer 1864 * ACKs can update the window size. 1865 * also avoids the state where snd_wl2 1866 * is eventually larger than th_ack and thus 1867 * blocking the window update mechanism and 1868 * the connection gets stuck for a loooong 1869 * time in the zero sized send window state. 1870 * 1871 * see PR/kern 55567 1872 */ 1873 tp->snd_wl2 = tp->snd_una; 1874 1875 m_freem(m); 1876 1877 /* 1878 * If all outstanding data are acked, stop 1879 * retransmit timer, otherwise restart timer 1880 * using current (possibly backed-off) value. 1881 * If process is waiting for space, 1882 * wakeup/selnotify/signal. If data 1883 * are ready to send, let tcp_output 1884 * decide between more output or persist. 1885 */ 1886 if (tp->snd_una == tp->snd_max) 1887 TCP_TIMER_DISARM(tp, TCPT_REXMT); 1888 else if (TCP_TIMER_ISARMED(tp, 1889 TCPT_PERSIST) == 0) 1890 TCP_TIMER_ARM(tp, TCPT_REXMT, 1891 tp->t_rxtcur); 1892 1893 sowwakeup(so); 1894 if (so->so_snd.sb_cc) { 1895 KERNEL_LOCK(1, NULL); 1896 (void)tcp_output(tp); 1897 KERNEL_UNLOCK_ONE(NULL); 1898 } 1899 m_freem(tcp_saveti); 1900 return; 1901 } 1902 } else if (th->th_ack == tp->snd_una && 1903 TAILQ_FIRST(&tp->segq) == NULL && 1904 tlen <= sbspace(&so->so_rcv)) { 1905 int newsize = 0; 1906 1907 /* 1908 * this is a pure, in-sequence data packet 1909 * with nothing on the reassembly queue and 1910 * we have enough buffer space to take it. 1911 */ 1912 tp->rcv_nxt += tlen; 1913 1914 /* 1915 * Pull rcv_up up to prevent seq wrap relative to 1916 * rcv_nxt. 1917 */ 1918 tp->rcv_up = tp->rcv_nxt; 1919 1920 /* 1921 * Pull snd_wl1 up to prevent seq wrap relative to 1922 * th_seq. 1923 */ 1924 tp->snd_wl1 = th->th_seq; 1925 1926 tcps = TCP_STAT_GETREF(); 1927 _NET_STATINC_REF(tcps, TCP_STAT_PREDDAT); 1928 _NET_STATINC_REF(tcps, TCP_STAT_RCVPACK); 1929 _NET_STATADD_REF(tcps, TCP_STAT_RCVBYTE, tlen); 1930 TCP_STAT_PUTREF(); 1931 nd_hint(tp); 1932 /* 1933 * Automatic sizing enables the performance of large buffers 1934 * and most of the efficiency of small ones by only allocating 1935 * space when it is needed. 1936 * 1937 * On the receive side the socket buffer memory is only rarely 1938 * used to any significant extent. This allows us to be much 1939 * more aggressive in scaling the receive socket buffer. For 1940 * the case that the buffer space is actually used to a large 1941 * extent and we run out of kernel memory we can simply drop 1942 * the new segments; TCP on the sender will just retransmit it 1943 * later. Setting the buffer size too big may only consume too 1944 * much kernel memory if the application doesn't read() from 1945 * the socket or packet loss or reordering makes use of the 1946 * reassembly queue. 1947 * 1948 * The criteria to step up the receive buffer one notch are: 1949 * 1. the number of bytes received during the time it takes 1950 * one timestamp to be reflected back to us (the RTT); 1951 * 2. received bytes per RTT is within seven eighth of the 1952 * current socket buffer size; 1953 * 3. receive buffer size has not hit maximal automatic size; 1954 * 1955 * This algorithm does one step per RTT at most and only if 1956 * we receive a bulk stream w/o packet losses or reorderings. 1957 * Shrinking the buffer during idle times is not necessary as 1958 * it doesn't consume any memory when idle. 1959 * 1960 * TODO: Only step up if the application is actually serving 1961 * the buffer to better manage the socket buffer resources. 1962 */ 1963 if (tcp_do_autorcvbuf && 1964 opti.ts_ecr && 1965 (so->so_rcv.sb_flags & SB_AUTOSIZE)) { 1966 if (opti.ts_ecr > tp->rfbuf_ts && 1967 opti.ts_ecr - tp->rfbuf_ts < PR_SLOWHZ) { 1968 if (tp->rfbuf_cnt > 1969 (so->so_rcv.sb_hiwat / 8 * 7) && 1970 so->so_rcv.sb_hiwat < 1971 tcp_autorcvbuf_max) { 1972 newsize = 1973 uimin(so->so_rcv.sb_hiwat + 1974 tcp_autorcvbuf_inc, 1975 tcp_autorcvbuf_max); 1976 } 1977 /* Start over with next RTT. */ 1978 tp->rfbuf_ts = 0; 1979 tp->rfbuf_cnt = 0; 1980 } else 1981 tp->rfbuf_cnt += tlen; /* add up */ 1982 } 1983 1984 /* 1985 * Drop TCP, IP headers and TCP options then add data 1986 * to socket buffer. 1987 */ 1988 if (so->so_state & SS_CANTRCVMORE) { 1989 m_freem(m); 1990 } else { 1991 /* 1992 * Set new socket buffer size. 1993 * Give up when limit is reached. 1994 */ 1995 if (newsize) 1996 if (!sbreserve(&so->so_rcv, 1997 newsize, so)) 1998 so->so_rcv.sb_flags &= ~SB_AUTOSIZE; 1999 m_adj(m, off + thlen); 2000 sbappendstream(&so->so_rcv, m); 2001 } 2002 sorwakeup(so); 2003 tcp_setup_ack(tp, th); 2004 if (tp->t_flags & TF_ACKNOW) { 2005 KERNEL_LOCK(1, NULL); 2006 (void)tcp_output(tp); 2007 KERNEL_UNLOCK_ONE(NULL); 2008 } 2009 m_freem(tcp_saveti); 2010 return; 2011 } 2012 } 2013 2014 /* 2015 * Compute mbuf offset to TCP data segment. 2016 */ 2017 hdroptlen = off + thlen; 2018 2019 /* 2020 * Calculate amount of space in receive window. Receive window is 2021 * amount of space in rcv queue, but not less than advertised 2022 * window. 2023 */ 2024 { 2025 int win; 2026 win = sbspace(&so->so_rcv); 2027 if (win < 0) 2028 win = 0; 2029 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 2030 } 2031 2032 /* Reset receive buffer auto scaling when not in bulk receive mode. */ 2033 tp->rfbuf_ts = 0; 2034 tp->rfbuf_cnt = 0; 2035 2036 switch (tp->t_state) { 2037 /* 2038 * If the state is SYN_SENT: 2039 * if seg contains an ACK, but not for our SYN, drop the input. 2040 * if seg contains a RST, then drop the connection. 2041 * if seg does not contain SYN, then drop it. 2042 * Otherwise this is an acceptable SYN segment 2043 * initialize tp->rcv_nxt and tp->irs 2044 * if seg contains ack then advance tp->snd_una 2045 * if seg contains a ECE and ECN support is enabled, the stream 2046 * is ECN capable. 2047 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 2048 * arrange for segment to be acked (eventually) 2049 * continue processing rest of data/controls, beginning with URG 2050 */ 2051 case TCPS_SYN_SENT: 2052 if ((tiflags & TH_ACK) && 2053 (SEQ_LEQ(th->th_ack, tp->iss) || 2054 SEQ_GT(th->th_ack, tp->snd_max))) 2055 goto dropwithreset; 2056 if (tiflags & TH_RST) { 2057 if (tiflags & TH_ACK) 2058 tp = tcp_drop(tp, ECONNREFUSED); 2059 goto drop; 2060 } 2061 if ((tiflags & TH_SYN) == 0) 2062 goto drop; 2063 if (tiflags & TH_ACK) { 2064 tp->snd_una = th->th_ack; 2065 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2066 tp->snd_nxt = tp->snd_una; 2067 if (SEQ_LT(tp->snd_high, tp->snd_una)) 2068 tp->snd_high = tp->snd_una; 2069 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2070 2071 if ((tiflags & TH_ECE) && tcp_do_ecn) { 2072 tp->t_flags |= TF_ECN_PERMIT; 2073 TCP_STATINC(TCP_STAT_ECN_SHS); 2074 } 2075 } 2076 tp->irs = th->th_seq; 2077 tcp_rcvseqinit(tp); 2078 tp->t_flags |= TF_ACKNOW; 2079 tcp_mss_from_peer(tp, opti.maxseg); 2080 2081 /* 2082 * Initialize the initial congestion window. If we 2083 * had to retransmit the SYN, we must initialize cwnd 2084 * to 1 segment (i.e. the Loss Window). 2085 */ 2086 if (tp->t_flags & TF_SYN_REXMT) 2087 tp->snd_cwnd = tp->t_peermss; 2088 else { 2089 int ss = tcp_init_win; 2090 if (inp->inp_af == AF_INET && in_localaddr(in4p_faddr(inp))) 2091 ss = tcp_init_win_local; 2092 #ifdef INET6 2093 else if (inp->inp_af == AF_INET6 && in6_localaddr(&in6p_faddr(inp))) 2094 ss = tcp_init_win_local; 2095 #endif 2096 tp->snd_cwnd = TCP_INITIAL_WINDOW(ss, tp->t_peermss); 2097 } 2098 2099 tcp_rmx_rtt(tp); 2100 if (tiflags & TH_ACK) { 2101 TCP_STATINC(TCP_STAT_CONNECTS); 2102 /* 2103 * move tcp_established before soisconnected 2104 * because upcall handler can drive tcp_output 2105 * functionality. 2106 * XXX we might call soisconnected at the end of 2107 * all processing 2108 */ 2109 tcp_established(tp); 2110 soisconnected(so); 2111 /* Do window scaling on this connection? */ 2112 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2113 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2114 tp->snd_scale = tp->requested_s_scale; 2115 tp->rcv_scale = tp->request_r_scale; 2116 } 2117 TCP_REASS_LOCK(tp); 2118 (void)tcp_reass(tp, NULL, NULL, tlen); 2119 /* 2120 * if we didn't have to retransmit the SYN, 2121 * use its rtt as our initial srtt & rtt var. 2122 */ 2123 if (tp->t_rtttime) 2124 tcp_xmit_timer(tp, tcp_now - tp->t_rtttime); 2125 } else { 2126 tp->t_state = TCPS_SYN_RECEIVED; 2127 } 2128 2129 /* 2130 * Advance th->th_seq to correspond to first data byte. 2131 * If data, trim to stay within window, 2132 * dropping FIN if necessary. 2133 */ 2134 th->th_seq++; 2135 if (tlen > tp->rcv_wnd) { 2136 todrop = tlen - tp->rcv_wnd; 2137 m_adj(m, -todrop); 2138 tlen = tp->rcv_wnd; 2139 tiflags &= ~TH_FIN; 2140 tcps = TCP_STAT_GETREF(); 2141 _NET_STATINC_REF(tcps, TCP_STAT_RCVPACKAFTERWIN); 2142 _NET_STATADD_REF(tcps, TCP_STAT_RCVBYTEAFTERWIN, 2143 todrop); 2144 TCP_STAT_PUTREF(); 2145 } 2146 tp->snd_wl1 = th->th_seq - 1; 2147 tp->rcv_up = th->th_seq; 2148 goto step6; 2149 2150 /* 2151 * If the state is SYN_RECEIVED: 2152 * If seg contains an ACK, but not for our SYN, drop the input 2153 * and generate an RST. See page 36, rfc793 2154 */ 2155 case TCPS_SYN_RECEIVED: 2156 if ((tiflags & TH_ACK) && 2157 (SEQ_LEQ(th->th_ack, tp->iss) || 2158 SEQ_GT(th->th_ack, tp->snd_max))) 2159 goto dropwithreset; 2160 break; 2161 } 2162 2163 /* 2164 * From here on, we're dealing with !LISTEN and !SYN_SENT. 2165 */ 2166 KASSERT(tp->t_state != TCPS_LISTEN && 2167 tp->t_state != TCPS_SYN_SENT); 2168 2169 /* 2170 * RFC1323 PAWS: if we have a timestamp reply on this segment and 2171 * it's less than ts_recent, drop it. 2172 */ 2173 if (opti.ts_present && (tiflags & TH_RST) == 0 && tp->ts_recent && 2174 TSTMP_LT(opti.ts_val, tp->ts_recent)) { 2175 /* Check to see if ts_recent is over 24 days old. */ 2176 if (tcp_now - tp->ts_recent_age > TCP_PAWS_IDLE) { 2177 /* 2178 * Invalidate ts_recent. If this segment updates 2179 * ts_recent, the age will be reset later and ts_recent 2180 * will get a valid value. If it does not, setting 2181 * ts_recent to zero will at least satisfy the 2182 * requirement that zero be placed in the timestamp 2183 * echo reply when ts_recent isn't valid. The 2184 * age isn't reset until we get a valid ts_recent 2185 * because we don't want out-of-order segments to be 2186 * dropped when ts_recent is old. 2187 */ 2188 tp->ts_recent = 0; 2189 } else { 2190 tcps = TCP_STAT_GETREF(); 2191 _NET_STATINC_REF(tcps, TCP_STAT_RCVDUPPACK); 2192 _NET_STATADD_REF(tcps, TCP_STAT_RCVDUPBYTE, tlen); 2193 _NET_STATINC_REF(tcps, TCP_STAT_PAWSDROP); 2194 TCP_STAT_PUTREF(); 2195 tcp_new_dsack(tp, th->th_seq, tlen); 2196 goto dropafterack; 2197 } 2198 } 2199 2200 /* 2201 * Check that at least some bytes of the segment are within the 2202 * receive window. If segment begins before rcv_nxt, drop leading 2203 * data (and SYN); if nothing left, just ack. 2204 */ 2205 todrop = tp->rcv_nxt - th->th_seq; 2206 dupseg = false; 2207 if (todrop > 0) { 2208 if (tiflags & TH_SYN) { 2209 tiflags &= ~TH_SYN; 2210 th->th_seq++; 2211 tcp_urp_drop(th, 1, &tiflags); 2212 todrop--; 2213 } 2214 if (todrop > tlen || 2215 (todrop == tlen && (tiflags & TH_FIN) == 0)) { 2216 /* 2217 * Any valid FIN or RST must be to the left of the 2218 * window. At this point the FIN or RST must be a 2219 * duplicate or out of sequence; drop it. 2220 */ 2221 if (tiflags & TH_RST) 2222 goto drop; 2223 tiflags &= ~(TH_FIN|TH_RST); 2224 2225 /* 2226 * Send an ACK to resynchronize and drop any data. 2227 * But keep on processing for RST or ACK. 2228 */ 2229 tp->t_flags |= TF_ACKNOW; 2230 todrop = tlen; 2231 dupseg = true; 2232 tcps = TCP_STAT_GETREF(); 2233 _NET_STATINC_REF(tcps, TCP_STAT_RCVDUPPACK); 2234 _NET_STATADD_REF(tcps, TCP_STAT_RCVDUPBYTE, todrop); 2235 TCP_STAT_PUTREF(); 2236 } else if ((tiflags & TH_RST) && th->th_seq != tp->rcv_nxt) { 2237 /* 2238 * Test for reset before adjusting the sequence 2239 * number for overlapping data. 2240 */ 2241 goto dropafterack_ratelim; 2242 } else { 2243 tcps = TCP_STAT_GETREF(); 2244 _NET_STATINC_REF(tcps, TCP_STAT_RCVPARTDUPPACK); 2245 _NET_STATADD_REF(tcps, TCP_STAT_RCVPARTDUPBYTE, 2246 todrop); 2247 TCP_STAT_PUTREF(); 2248 } 2249 tcp_new_dsack(tp, th->th_seq, todrop); 2250 hdroptlen += todrop; /* drop from head afterwards (m_adj) */ 2251 th->th_seq += todrop; 2252 tlen -= todrop; 2253 tcp_urp_drop(th, todrop, &tiflags); 2254 } 2255 2256 /* 2257 * If new data is received on a connection after the user processes 2258 * are gone, then RST the other end. 2259 */ 2260 if ((so->so_state & SS_NOFDREF) && 2261 tp->t_state > TCPS_CLOSE_WAIT && tlen) { 2262 tp = tcp_close(tp); 2263 TCP_STATINC(TCP_STAT_RCVAFTERCLOSE); 2264 goto dropwithreset; 2265 } 2266 2267 /* 2268 * If the segment ends after the window, drop trailing data (and 2269 * PUSH and FIN); if nothing left, just ACK. 2270 */ 2271 todrop = (th->th_seq + tlen) - (tp->rcv_nxt + tp->rcv_wnd); 2272 if (todrop > 0) { 2273 TCP_STATINC(TCP_STAT_RCVPACKAFTERWIN); 2274 if (todrop >= tlen) { 2275 /* 2276 * The segment actually starts after the window. 2277 * th->th_seq + tlen - tp->rcv_nxt - tp->rcv_wnd >= tlen 2278 * th->th_seq - tp->rcv_nxt - tp->rcv_wnd >= 0 2279 * th->th_seq >= tp->rcv_nxt + tp->rcv_wnd 2280 */ 2281 TCP_STATADD(TCP_STAT_RCVBYTEAFTERWIN, tlen); 2282 2283 /* 2284 * If a new connection request is received while in 2285 * TIME_WAIT, drop the old connection and start over 2286 * if the sequence numbers are above the previous 2287 * ones. 2288 * 2289 * NOTE: We need to put the header fields back into 2290 * network order. 2291 */ 2292 if ((tiflags & TH_SYN) && 2293 tp->t_state == TCPS_TIME_WAIT && 2294 SEQ_GT(th->th_seq, tp->rcv_nxt)) { 2295 tp = tcp_close(tp); 2296 tcp_fields_to_net(th); 2297 m_freem(tcp_saveti); 2298 tcp_saveti = NULL; 2299 goto findpcb; 2300 } 2301 2302 /* 2303 * If window is closed can only take segments at 2304 * window edge, and have to drop data and PUSH from 2305 * incoming segments. Continue processing, but 2306 * remember to ack. Otherwise, drop segment 2307 * and (if not RST) ack. 2308 */ 2309 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 2310 KASSERT(todrop == tlen); 2311 tp->t_flags |= TF_ACKNOW; 2312 TCP_STATINC(TCP_STAT_RCVWINPROBE); 2313 } else { 2314 goto dropafterack; 2315 } 2316 } else { 2317 TCP_STATADD(TCP_STAT_RCVBYTEAFTERWIN, todrop); 2318 } 2319 m_adj(m, -todrop); 2320 tlen -= todrop; 2321 tiflags &= ~(TH_PUSH|TH_FIN); 2322 } 2323 2324 /* 2325 * If last ACK falls within this segment's sequence numbers, 2326 * record the timestamp. 2327 * NOTE: 2328 * 1) That the test incorporates suggestions from the latest 2329 * proposal of the tcplw (at) cray.com list (Braden 1993/04/26). 2330 * 2) That updating only on newer timestamps interferes with 2331 * our earlier PAWS tests, so this check should be solely 2332 * predicated on the sequence space of this segment. 2333 * 3) That we modify the segment boundary check to be 2334 * Last.ACK.Sent <= SEG.SEQ + SEG.Len 2335 * instead of RFC1323's 2336 * Last.ACK.Sent < SEG.SEQ + SEG.Len, 2337 * This modified check allows us to overcome RFC1323's 2338 * limitations as described in Stevens TCP/IP Illustrated 2339 * Vol. 2 p.869. In such cases, we can still calculate the 2340 * RTT correctly when RCV.NXT == Last.ACK.Sent. 2341 */ 2342 if (opti.ts_present && 2343 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 2344 SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen + 2345 ((tiflags & (TH_SYN|TH_FIN)) != 0))) { 2346 tp->ts_recent_age = tcp_now; 2347 tp->ts_recent = opti.ts_val; 2348 } 2349 2350 /* 2351 * If the RST bit is set examine the state: 2352 * RECEIVED state: 2353 * If passive open, return to LISTEN state. 2354 * If active open, inform user that connection was refused. 2355 * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT states: 2356 * Inform user that connection was reset, and close tcb. 2357 * CLOSING, LAST_ACK, TIME_WAIT states: 2358 * Close the tcb. 2359 */ 2360 if (tiflags & TH_RST) { 2361 if (th->th_seq != tp->rcv_nxt) 2362 goto dropafterack_ratelim; 2363 2364 switch (tp->t_state) { 2365 case TCPS_SYN_RECEIVED: 2366 so->so_error = ECONNREFUSED; 2367 goto close; 2368 2369 case TCPS_ESTABLISHED: 2370 case TCPS_FIN_WAIT_1: 2371 case TCPS_FIN_WAIT_2: 2372 case TCPS_CLOSE_WAIT: 2373 so->so_error = ECONNRESET; 2374 close: 2375 tp->t_state = TCPS_CLOSED; 2376 TCP_STATINC(TCP_STAT_DROPS); 2377 tp = tcp_close(tp); 2378 goto drop; 2379 2380 case TCPS_CLOSING: 2381 case TCPS_LAST_ACK: 2382 case TCPS_TIME_WAIT: 2383 tp = tcp_close(tp); 2384 goto drop; 2385 } 2386 } 2387 2388 /* 2389 * Since we've covered the SYN-SENT and SYN-RECEIVED states above 2390 * we must be in a synchronized state. RFC793 states (under Reset 2391 * Generation) that any unacceptable segment (an out-of-order SYN 2392 * qualifies) received in a synchronized state must elicit only an 2393 * empty acknowledgment segment ... and the connection remains in 2394 * the same state. 2395 */ 2396 if (tiflags & TH_SYN) { 2397 if (tp->rcv_nxt == th->th_seq) { 2398 tcp_respond(tp, m, m, th, (tcp_seq)0, th->th_ack - 1, 2399 TH_ACK); 2400 m_freem(tcp_saveti); 2401 return; 2402 } 2403 2404 goto dropafterack_ratelim; 2405 } 2406 2407 /* 2408 * If the ACK bit is off we drop the segment and return. 2409 */ 2410 if ((tiflags & TH_ACK) == 0) { 2411 if (tp->t_flags & TF_ACKNOW) 2412 goto dropafterack; 2413 goto drop; 2414 } 2415 2416 /* 2417 * From here on, we're doing ACK processing. 2418 */ 2419 2420 switch (tp->t_state) { 2421 /* 2422 * In SYN_RECEIVED state if the ack ACKs our SYN then enter 2423 * ESTABLISHED state and continue processing, otherwise 2424 * send an RST. 2425 */ 2426 case TCPS_SYN_RECEIVED: 2427 if (SEQ_GT(tp->snd_una, th->th_ack) || 2428 SEQ_GT(th->th_ack, tp->snd_max)) 2429 goto dropwithreset; 2430 TCP_STATINC(TCP_STAT_CONNECTS); 2431 soisconnected(so); 2432 tcp_established(tp); 2433 /* Do window scaling? */ 2434 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2435 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2436 tp->snd_scale = tp->requested_s_scale; 2437 tp->rcv_scale = tp->request_r_scale; 2438 } 2439 TCP_REASS_LOCK(tp); 2440 (void)tcp_reass(tp, NULL, NULL, tlen); 2441 tp->snd_wl1 = th->th_seq - 1; 2442 /* FALLTHROUGH */ 2443 2444 /* 2445 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 2446 * ACKs. If the ack is in the range 2447 * tp->snd_una < th->th_ack <= tp->snd_max 2448 * then advance tp->snd_una to th->th_ack and drop 2449 * data from the retransmission queue. If this ACK reflects 2450 * more up to date window information we update our window information. 2451 */ 2452 case TCPS_ESTABLISHED: 2453 case TCPS_FIN_WAIT_1: 2454 case TCPS_FIN_WAIT_2: 2455 case TCPS_CLOSE_WAIT: 2456 case TCPS_CLOSING: 2457 case TCPS_LAST_ACK: 2458 case TCPS_TIME_WAIT: 2459 if (SEQ_LEQ(th->th_ack, tp->snd_una)) { 2460 if (tlen == 0 && !dupseg && tiwin == tp->snd_wnd) { 2461 TCP_STATINC(TCP_STAT_RCVDUPACK); 2462 /* 2463 * If we have outstanding data (other than 2464 * a window probe), this is a completely 2465 * duplicate ack (ie, window info didn't 2466 * change), the ack is the biggest we've 2467 * seen and we've seen exactly our rexmt 2468 * threshold of them, assume a packet 2469 * has been dropped and retransmit it. 2470 * Kludge snd_nxt & the congestion 2471 * window so we send only this one 2472 * packet. 2473 */ 2474 if (TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 || 2475 th->th_ack != tp->snd_una) 2476 tp->t_dupacks = 0; 2477 else if (tp->t_partialacks < 0 && 2478 (++tp->t_dupacks == tcprexmtthresh || 2479 TCP_FACK_FASTRECOV(tp))) { 2480 /* 2481 * Do the fast retransmit, and adjust 2482 * congestion control parameters. 2483 */ 2484 if (tp->t_congctl->fast_retransmit(tp, th)) { 2485 /* False fast retransmit */ 2486 break; 2487 } 2488 goto drop; 2489 } else if (tp->t_dupacks > tcprexmtthresh) { 2490 tp->snd_cwnd += tp->t_segsz; 2491 KERNEL_LOCK(1, NULL); 2492 (void)tcp_output(tp); 2493 KERNEL_UNLOCK_ONE(NULL); 2494 goto drop; 2495 } 2496 } else { 2497 /* 2498 * If the ack appears to be very old, only 2499 * allow data that is in-sequence. This 2500 * makes it somewhat more difficult to insert 2501 * forged data by guessing sequence numbers. 2502 * Sent an ack to try to update the send 2503 * sequence number on the other side. 2504 */ 2505 if (tlen && th->th_seq != tp->rcv_nxt && 2506 SEQ_LT(th->th_ack, 2507 tp->snd_una - tp->max_sndwnd)) 2508 goto dropafterack; 2509 } 2510 break; 2511 } 2512 /* 2513 * If the congestion window was inflated to account 2514 * for the other side's cached packets, retract it. 2515 */ 2516 tp->t_congctl->fast_retransmit_newack(tp, th); 2517 2518 if (SEQ_GT(th->th_ack, tp->snd_max)) { 2519 TCP_STATINC(TCP_STAT_RCVACKTOOMUCH); 2520 goto dropafterack; 2521 } 2522 acked = th->th_ack - tp->snd_una; 2523 tcps = TCP_STAT_GETREF(); 2524 _NET_STATINC_REF(tcps, TCP_STAT_RCVACKPACK); 2525 _NET_STATADD_REF(tcps, TCP_STAT_RCVACKBYTE, acked); 2526 TCP_STAT_PUTREF(); 2527 2528 /* 2529 * If we have a timestamp reply, update smoothed 2530 * round trip time. If no timestamp is present but 2531 * transmit timer is running and timed sequence 2532 * number was acked, update smoothed round trip time. 2533 * Since we now have an rtt measurement, cancel the 2534 * timer backoff (cf., Phil Karn's retransmit alg.). 2535 * Recompute the initial retransmit timer. 2536 */ 2537 if (ts_rtt) 2538 tcp_xmit_timer(tp, ts_rtt - 1); 2539 else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) 2540 tcp_xmit_timer(tp, tcp_now - tp->t_rtttime); 2541 2542 /* 2543 * If all outstanding data is acked, stop retransmit 2544 * timer and remember to restart (more output or persist). 2545 * If there is more data to be acked, restart retransmit 2546 * timer, using current (possibly backed-off) value. 2547 */ 2548 if (th->th_ack == tp->snd_max) { 2549 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2550 needoutput = 1; 2551 } else if (TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) 2552 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 2553 2554 /* 2555 * New data has been acked, adjust the congestion window. 2556 */ 2557 tp->t_congctl->newack(tp, th); 2558 2559 nd_hint(tp); 2560 if (acked > so->so_snd.sb_cc) { 2561 tp->snd_wnd -= so->so_snd.sb_cc; 2562 sbdrop(&so->so_snd, (int)so->so_snd.sb_cc); 2563 ourfinisacked = 1; 2564 } else { 2565 if (acked > (tp->t_lastoff - tp->t_inoff)) 2566 tp->t_lastm = NULL; 2567 sbdrop(&so->so_snd, acked); 2568 tp->t_lastoff -= acked; 2569 if (tp->snd_wnd > acked) 2570 tp->snd_wnd -= acked; 2571 else 2572 tp->snd_wnd = 0; 2573 ourfinisacked = 0; 2574 } 2575 sowwakeup(so); 2576 2577 icmp_check(tp, th, acked); 2578 2579 tp->snd_una = th->th_ack; 2580 if (SEQ_GT(tp->snd_una, tp->snd_fack)) 2581 tp->snd_fack = tp->snd_una; 2582 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2583 tp->snd_nxt = tp->snd_una; 2584 if (SEQ_LT(tp->snd_high, tp->snd_una)) 2585 tp->snd_high = tp->snd_una; 2586 2587 switch (tp->t_state) { 2588 2589 /* 2590 * In FIN_WAIT_1 STATE in addition to the processing 2591 * for the ESTABLISHED state if our FIN is now acknowledged 2592 * then enter FIN_WAIT_2. 2593 */ 2594 case TCPS_FIN_WAIT_1: 2595 if (ourfinisacked) { 2596 /* 2597 * If we can't receive any more 2598 * data, then closing user can proceed. 2599 * Starting the timer is contrary to the 2600 * specification, but if we don't get a FIN 2601 * we'll hang forever. 2602 */ 2603 if (so->so_state & SS_CANTRCVMORE) { 2604 soisdisconnected(so); 2605 if (tp->t_maxidle > 0) 2606 TCP_TIMER_ARM(tp, TCPT_2MSL, 2607 tp->t_maxidle); 2608 } 2609 tp->t_state = TCPS_FIN_WAIT_2; 2610 } 2611 break; 2612 2613 /* 2614 * In CLOSING STATE in addition to the processing for 2615 * the ESTABLISHED state if the ACK acknowledges our FIN 2616 * then enter the TIME-WAIT state, otherwise ignore 2617 * the segment. 2618 */ 2619 case TCPS_CLOSING: 2620 if (ourfinisacked) { 2621 tp->t_state = TCPS_TIME_WAIT; 2622 tcp_canceltimers(tp); 2623 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * tp->t_msl); 2624 soisdisconnected(so); 2625 } 2626 break; 2627 2628 /* 2629 * In LAST_ACK, we may still be waiting for data to drain 2630 * and/or to be acked, as well as for the ack of our FIN. 2631 * If our FIN is now acknowledged, delete the TCB, 2632 * enter the closed state and return. 2633 */ 2634 case TCPS_LAST_ACK: 2635 if (ourfinisacked) { 2636 tp = tcp_close(tp); 2637 goto drop; 2638 } 2639 break; 2640 2641 /* 2642 * In TIME_WAIT state the only thing that should arrive 2643 * is a retransmission of the remote FIN. Acknowledge 2644 * it and restart the finack timer. 2645 */ 2646 case TCPS_TIME_WAIT: 2647 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * tp->t_msl); 2648 goto dropafterack; 2649 } 2650 } 2651 2652 step6: 2653 /* 2654 * Update window information. 2655 * Don't look at window if no ACK: TAC's send garbage on first SYN. 2656 */ 2657 if ((tiflags & TH_ACK) && (SEQ_LT(tp->snd_wl1, th->th_seq) || 2658 (tp->snd_wl1 == th->th_seq && (SEQ_LT(tp->snd_wl2, th->th_ack) || 2659 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))) { 2660 /* keep track of pure window updates */ 2661 if (tlen == 0 && 2662 tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) 2663 TCP_STATINC(TCP_STAT_RCVWINUPD); 2664 tp->snd_wnd = tiwin; 2665 tp->snd_wl1 = th->th_seq; 2666 tp->snd_wl2 = th->th_ack; 2667 if (tp->snd_wnd > tp->max_sndwnd) 2668 tp->max_sndwnd = tp->snd_wnd; 2669 needoutput = 1; 2670 } 2671 2672 /* 2673 * Process segments with URG. 2674 */ 2675 if ((tiflags & TH_URG) && th->th_urp && 2676 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2677 /* 2678 * This is a kludge, but if we receive and accept 2679 * random urgent pointers, we'll crash in 2680 * soreceive. It's hard to imagine someone 2681 * actually wanting to send this much urgent data. 2682 */ 2683 if (th->th_urp + so->so_rcv.sb_cc > sb_max) { 2684 th->th_urp = 0; /* XXX */ 2685 tiflags &= ~TH_URG; /* XXX */ 2686 goto dodata; /* XXX */ 2687 } 2688 2689 /* 2690 * If this segment advances the known urgent pointer, 2691 * then mark the data stream. This should not happen 2692 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 2693 * a FIN has been received from the remote side. 2694 * In these states we ignore the URG. 2695 * 2696 * According to RFC961 (Assigned Protocols), 2697 * the urgent pointer points to the last octet 2698 * of urgent data. We continue, however, 2699 * to consider it to indicate the first octet 2700 * of data past the urgent section as the original 2701 * spec states (in one of two places). 2702 */ 2703 if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) { 2704 tp->rcv_up = th->th_seq + th->th_urp; 2705 so->so_oobmark = so->so_rcv.sb_cc + 2706 (tp->rcv_up - tp->rcv_nxt) - 1; 2707 if (so->so_oobmark == 0) 2708 so->so_state |= SS_RCVATMARK; 2709 sohasoutofband(so); 2710 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); 2711 } 2712 2713 /* 2714 * Remove out of band data so doesn't get presented to user. 2715 * This can happen independent of advancing the URG pointer, 2716 * but if two URG's are pending at once, some out-of-band 2717 * data may creep in... ick. 2718 */ 2719 if (th->th_urp <= (u_int16_t)tlen && 2720 (so->so_options & SO_OOBINLINE) == 0) 2721 tcp_pulloutofband(so, th, m, hdroptlen); 2722 } else { 2723 /* 2724 * If no out of band data is expected, 2725 * pull receive urgent pointer along 2726 * with the receive window. 2727 */ 2728 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) 2729 tp->rcv_up = tp->rcv_nxt; 2730 } 2731 dodata: 2732 2733 /* 2734 * Process the segment text, merging it into the TCP sequencing queue, 2735 * and arranging for acknowledgement of receipt if necessary. 2736 * This process logically involves adjusting tp->rcv_wnd as data 2737 * is presented to the user (this happens in tcp_usrreq.c, 2738 * tcp_rcvd()). If a FIN has already been received on this 2739 * connection then we just ignore the text. 2740 */ 2741 if ((tlen || (tiflags & TH_FIN)) && 2742 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2743 /* 2744 * Handle the common case: 2745 * o Segment is the next to be received, and 2746 * o The queue is empty, and 2747 * o The connection is established 2748 * In this case, we avoid calling tcp_reass. 2749 * 2750 * tcp_setup_ack: set DELACK for segments received in order, 2751 * but ack immediately when segments are out of order (so that 2752 * fast retransmit can work). 2753 */ 2754 TCP_REASS_LOCK(tp); 2755 if (th->th_seq == tp->rcv_nxt && 2756 TAILQ_FIRST(&tp->segq) == NULL && 2757 tp->t_state == TCPS_ESTABLISHED) { 2758 tcp_setup_ack(tp, th); 2759 tp->rcv_nxt += tlen; 2760 tiflags = th->th_flags & TH_FIN; 2761 tcps = TCP_STAT_GETREF(); 2762 _NET_STATINC_REF(tcps, TCP_STAT_RCVPACK); 2763 _NET_STATADD_REF(tcps, TCP_STAT_RCVBYTE, tlen); 2764 TCP_STAT_PUTREF(); 2765 nd_hint(tp); 2766 if (so->so_state & SS_CANTRCVMORE) { 2767 m_freem(m); 2768 } else { 2769 m_adj(m, hdroptlen); 2770 sbappendstream(&(so)->so_rcv, m); 2771 } 2772 TCP_REASS_UNLOCK(tp); 2773 sorwakeup(so); 2774 } else { 2775 m_adj(m, hdroptlen); 2776 tiflags = tcp_reass(tp, th, m, tlen); 2777 tp->t_flags |= TF_ACKNOW; 2778 } 2779 2780 /* 2781 * Note the amount of data that peer has sent into 2782 * our window, in order to estimate the sender's 2783 * buffer size. 2784 */ 2785 len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); 2786 } else { 2787 m_freem(m); 2788 m = NULL; 2789 tiflags &= ~TH_FIN; 2790 } 2791 2792 /* 2793 * If FIN is received ACK the FIN and let the user know 2794 * that the connection is closing. Ignore a FIN received before 2795 * the connection is fully established. 2796 */ 2797 if ((tiflags & TH_FIN) && TCPS_HAVEESTABLISHED(tp->t_state)) { 2798 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2799 socantrcvmore(so); 2800 tp->t_flags |= TF_ACKNOW; 2801 tp->rcv_nxt++; 2802 } 2803 switch (tp->t_state) { 2804 2805 /* 2806 * In ESTABLISHED STATE enter the CLOSE_WAIT state. 2807 */ 2808 case TCPS_ESTABLISHED: 2809 tp->t_state = TCPS_CLOSE_WAIT; 2810 break; 2811 2812 /* 2813 * If still in FIN_WAIT_1 STATE FIN has not been acked so 2814 * enter the CLOSING state. 2815 */ 2816 case TCPS_FIN_WAIT_1: 2817 tp->t_state = TCPS_CLOSING; 2818 break; 2819 2820 /* 2821 * In FIN_WAIT_2 state enter the TIME_WAIT state, 2822 * starting the time-wait timer, turning off the other 2823 * standard timers. 2824 */ 2825 case TCPS_FIN_WAIT_2: 2826 tp->t_state = TCPS_TIME_WAIT; 2827 tcp_canceltimers(tp); 2828 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * tp->t_msl); 2829 soisdisconnected(so); 2830 break; 2831 2832 /* 2833 * In TIME_WAIT state restart the 2 MSL time_wait timer. 2834 */ 2835 case TCPS_TIME_WAIT: 2836 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * tp->t_msl); 2837 break; 2838 } 2839 } 2840 #ifdef TCP_DEBUG 2841 if (so->so_options & SO_DEBUG) 2842 tcp_trace(TA_INPUT, ostate, tp, tcp_saveti, 0); 2843 #endif 2844 2845 /* 2846 * Return any desired output. 2847 */ 2848 if (needoutput || (tp->t_flags & TF_ACKNOW)) { 2849 KERNEL_LOCK(1, NULL); 2850 (void)tcp_output(tp); 2851 KERNEL_UNLOCK_ONE(NULL); 2852 } 2853 m_freem(tcp_saveti); 2854 2855 if (tp->t_state == TCPS_TIME_WAIT 2856 && (so->so_state & SS_NOFDREF) 2857 && (tp->t_inpcb || af != AF_INET || af != AF_INET6) 2858 && ((af == AF_INET ? tcp4_vtw_enable : tcp6_vtw_enable) & 1) != 0 2859 && TAILQ_EMPTY(&tp->segq) 2860 && vtw_add(af, tp)) { 2861 ; 2862 } 2863 return; 2864 2865 badsyn: 2866 /* 2867 * Received a bad SYN. Increment counters and dropwithreset. 2868 */ 2869 TCP_STATINC(TCP_STAT_BADSYN); 2870 tp = NULL; 2871 goto dropwithreset; 2872 2873 dropafterack: 2874 /* 2875 * Generate an ACK dropping incoming segment if it occupies 2876 * sequence space, where the ACK reflects our state. 2877 */ 2878 if (tiflags & TH_RST) 2879 goto drop; 2880 goto dropafterack2; 2881 2882 dropafterack_ratelim: 2883 /* 2884 * We may want to rate-limit ACKs against SYN/RST attack. 2885 */ 2886 if (ppsratecheck(&tcp_ackdrop_ppslim_last, &tcp_ackdrop_ppslim_count, 2887 tcp_ackdrop_ppslim) == 0) { 2888 /* XXX stat */ 2889 goto drop; 2890 } 2891 2892 dropafterack2: 2893 m_freem(m); 2894 tp->t_flags |= TF_ACKNOW; 2895 KERNEL_LOCK(1, NULL); 2896 (void)tcp_output(tp); 2897 KERNEL_UNLOCK_ONE(NULL); 2898 m_freem(tcp_saveti); 2899 return; 2900 2901 dropwithreset_ratelim: 2902 /* 2903 * We may want to rate-limit RSTs in certain situations, 2904 * particularly if we are sending an RST in response to 2905 * an attempt to connect to or otherwise communicate with 2906 * a port for which we have no socket. 2907 */ 2908 if (ppsratecheck(&tcp_rst_ppslim_last, &tcp_rst_ppslim_count, 2909 tcp_rst_ppslim) == 0) { 2910 /* XXX stat */ 2911 goto drop; 2912 } 2913 2914 dropwithreset: 2915 /* 2916 * Generate a RST, dropping incoming segment. 2917 * Make ACK acceptable to originator of segment. 2918 */ 2919 if (tiflags & TH_RST) 2920 goto drop; 2921 if (tiflags & TH_ACK) { 2922 (void)tcp_respond(tp, m, m, th, (tcp_seq)0, th->th_ack, TH_RST); 2923 } else { 2924 if (tiflags & TH_SYN) 2925 tlen++; 2926 (void)tcp_respond(tp, m, m, th, th->th_seq + tlen, (tcp_seq)0, 2927 TH_RST|TH_ACK); 2928 } 2929 m_freem(tcp_saveti); 2930 return; 2931 2932 badcsum: 2933 drop: 2934 /* 2935 * Drop space held by incoming segment and return. 2936 */ 2937 if (tp) { 2938 so = tp->t_inpcb->inp_socket; 2939 #ifdef TCP_DEBUG 2940 if (so && (so->so_options & SO_DEBUG) != 0) 2941 tcp_trace(TA_DROP, ostate, tp, tcp_saveti, 0); 2942 #endif 2943 } 2944 m_freem(tcp_saveti); 2945 m_freem(m); 2946 return; 2947 } 2948 2949 #ifdef TCP_SIGNATURE 2950 int 2951 tcp_signature_apply(void *fstate, void *data, u_int len) 2952 { 2953 2954 MD5Update(fstate, (u_char *)data, len); 2955 return (0); 2956 } 2957 2958 struct secasvar * 2959 tcp_signature_getsav(struct mbuf *m) 2960 { 2961 struct ip *ip; 2962 struct ip6_hdr *ip6; 2963 2964 ip = mtod(m, struct ip *); 2965 switch (ip->ip_v) { 2966 case 4: 2967 ip = mtod(m, struct ip *); 2968 ip6 = NULL; 2969 break; 2970 case 6: 2971 ip = NULL; 2972 ip6 = mtod(m, struct ip6_hdr *); 2973 break; 2974 default: 2975 return (NULL); 2976 } 2977 2978 #ifdef IPSEC 2979 union sockaddr_union dst; 2980 2981 /* Extract the destination from the IP header in the mbuf. */ 2982 memset(&dst, 0, sizeof(union sockaddr_union)); 2983 if (ip != NULL) { 2984 dst.sa.sa_len = sizeof(struct sockaddr_in); 2985 dst.sa.sa_family = AF_INET; 2986 dst.sin.sin_addr = ip->ip_dst; 2987 } else { 2988 dst.sa.sa_len = sizeof(struct sockaddr_in6); 2989 dst.sa.sa_family = AF_INET6; 2990 dst.sin6.sin6_addr = ip6->ip6_dst; 2991 } 2992 2993 /* 2994 * Look up an SADB entry which matches the address of the peer. 2995 */ 2996 return KEY_LOOKUP_SA(&dst, IPPROTO_TCP, htonl(TCP_SIG_SPI), 0, 0); 2997 #else 2998 return NULL; 2999 #endif 3000 } 3001 3002 int 3003 tcp_signature(struct mbuf *m, struct tcphdr *th, int thoff, 3004 struct secasvar *sav, char *sig) 3005 { 3006 MD5_CTX ctx; 3007 struct ip *ip; 3008 struct ipovly *ipovly; 3009 #ifdef INET6 3010 struct ip6_hdr *ip6; 3011 struct ip6_hdr_pseudo ip6pseudo; 3012 #endif 3013 struct ippseudo ippseudo; 3014 struct tcphdr th0; 3015 int l, tcphdrlen; 3016 3017 if (sav == NULL) 3018 return (-1); 3019 3020 tcphdrlen = th->th_off * 4; 3021 3022 switch (mtod(m, struct ip *)->ip_v) { 3023 case 4: 3024 MD5Init(&ctx); 3025 ip = mtod(m, struct ip *); 3026 memset(&ippseudo, 0, sizeof(ippseudo)); 3027 ipovly = (struct ipovly *)ip; 3028 ippseudo.ippseudo_src = ipovly->ih_src; 3029 ippseudo.ippseudo_dst = ipovly->ih_dst; 3030 ippseudo.ippseudo_pad = 0; 3031 ippseudo.ippseudo_p = IPPROTO_TCP; 3032 ippseudo.ippseudo_len = htons(m->m_pkthdr.len - thoff); 3033 MD5Update(&ctx, (char *)&ippseudo, sizeof(ippseudo)); 3034 break; 3035 #if INET6 3036 case 6: 3037 MD5Init(&ctx); 3038 ip6 = mtod(m, struct ip6_hdr *); 3039 memset(&ip6pseudo, 0, sizeof(ip6pseudo)); 3040 ip6pseudo.ip6ph_src = ip6->ip6_src; 3041 in6_clearscope(&ip6pseudo.ip6ph_src); 3042 ip6pseudo.ip6ph_dst = ip6->ip6_dst; 3043 in6_clearscope(&ip6pseudo.ip6ph_dst); 3044 ip6pseudo.ip6ph_len = htons(m->m_pkthdr.len - thoff); 3045 ip6pseudo.ip6ph_nxt = IPPROTO_TCP; 3046 MD5Update(&ctx, (char *)&ip6pseudo, sizeof(ip6pseudo)); 3047 break; 3048 #endif 3049 default: 3050 return (-1); 3051 } 3052 3053 th0 = *th; 3054 th0.th_sum = 0; 3055 MD5Update(&ctx, (char *)&th0, sizeof(th0)); 3056 3057 l = m->m_pkthdr.len - thoff - tcphdrlen; 3058 if (l > 0) 3059 m_apply(m, thoff + tcphdrlen, 3060 m->m_pkthdr.len - thoff - tcphdrlen, 3061 tcp_signature_apply, &ctx); 3062 3063 MD5Update(&ctx, _KEYBUF(sav->key_auth), _KEYLEN(sav->key_auth)); 3064 MD5Final(sig, &ctx); 3065 3066 return (0); 3067 } 3068 #endif 3069 3070 /* 3071 * Parse and process tcp options. 3072 * 3073 * Returns -1 if this segment should be dropped. (eg. wrong signature) 3074 * Otherwise returns 0. 3075 */ 3076 int 3077 tcp_dooptions(struct tcpcb *tp, const u_char *cp, int cnt, struct tcphdr *th, 3078 struct mbuf *m, int toff, struct tcp_opt_info *oi) 3079 { 3080 u_int16_t mss; 3081 int opt, optlen = 0; 3082 #ifdef TCP_SIGNATURE 3083 void *sigp = NULL; 3084 char sigbuf[TCP_SIGLEN]; 3085 struct secasvar *sav = NULL; 3086 #endif 3087 3088 for (; cp && cnt > 0; cnt -= optlen, cp += optlen) { 3089 opt = cp[0]; 3090 if (opt == TCPOPT_EOL) 3091 break; 3092 if (opt == TCPOPT_NOP) 3093 optlen = 1; 3094 else { 3095 if (cnt < 2) 3096 break; 3097 optlen = cp[1]; 3098 if (optlen < 2 || optlen > cnt) 3099 break; 3100 } 3101 switch (opt) { 3102 3103 default: 3104 continue; 3105 3106 case TCPOPT_MAXSEG: 3107 if (optlen != TCPOLEN_MAXSEG) 3108 continue; 3109 if (!(th->th_flags & TH_SYN)) 3110 continue; 3111 if (TCPS_HAVERCVDSYN(tp->t_state)) 3112 continue; 3113 memcpy(&mss, cp + 2, sizeof(mss)); 3114 oi->maxseg = ntohs(mss); 3115 break; 3116 3117 case TCPOPT_WINDOW: 3118 if (optlen != TCPOLEN_WINDOW) 3119 continue; 3120 if (!(th->th_flags & TH_SYN)) 3121 continue; 3122 if (TCPS_HAVERCVDSYN(tp->t_state)) 3123 continue; 3124 tp->t_flags |= TF_RCVD_SCALE; 3125 tp->requested_s_scale = cp[2]; 3126 if (tp->requested_s_scale > TCP_MAX_WINSHIFT) { 3127 char buf[INET6_ADDRSTRLEN]; 3128 struct ip *ip = mtod(m, struct ip *); 3129 #ifdef INET6 3130 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *); 3131 #endif 3132 3133 switch (ip->ip_v) { 3134 case 4: 3135 in_print(buf, sizeof(buf), 3136 &ip->ip_src); 3137 break; 3138 #ifdef INET6 3139 case 6: 3140 in6_print(buf, sizeof(buf), 3141 &ip6->ip6_src); 3142 break; 3143 #endif 3144 default: 3145 strlcpy(buf, "(unknown)", sizeof(buf)); 3146 break; 3147 } 3148 3149 log(LOG_ERR, "TCP: invalid wscale %d from %s, " 3150 "assuming %d\n", 3151 tp->requested_s_scale, buf, 3152 TCP_MAX_WINSHIFT); 3153 tp->requested_s_scale = TCP_MAX_WINSHIFT; 3154 } 3155 break; 3156 3157 case TCPOPT_TIMESTAMP: 3158 if (optlen != TCPOLEN_TIMESTAMP) 3159 continue; 3160 oi->ts_present = 1; 3161 memcpy(&oi->ts_val, cp + 2, sizeof(oi->ts_val)); 3162 NTOHL(oi->ts_val); 3163 memcpy(&oi->ts_ecr, cp + 6, sizeof(oi->ts_ecr)); 3164 NTOHL(oi->ts_ecr); 3165 3166 if (!(th->th_flags & TH_SYN)) 3167 continue; 3168 if (TCPS_HAVERCVDSYN(tp->t_state)) 3169 continue; 3170 /* 3171 * A timestamp received in a SYN makes 3172 * it ok to send timestamp requests and replies. 3173 */ 3174 tp->t_flags |= TF_RCVD_TSTMP; 3175 tp->ts_recent = oi->ts_val; 3176 tp->ts_recent_age = tcp_now; 3177 break; 3178 3179 case TCPOPT_SACK_PERMITTED: 3180 if (optlen != TCPOLEN_SACK_PERMITTED) 3181 continue; 3182 if (!(th->th_flags & TH_SYN)) 3183 continue; 3184 if (TCPS_HAVERCVDSYN(tp->t_state)) 3185 continue; 3186 if (tcp_do_sack) { 3187 tp->t_flags |= TF_SACK_PERMIT; 3188 tp->t_flags |= TF_WILL_SACK; 3189 } 3190 break; 3191 3192 case TCPOPT_SACK: 3193 tcp_sack_option(tp, th, cp, optlen); 3194 break; 3195 #ifdef TCP_SIGNATURE 3196 case TCPOPT_SIGNATURE: 3197 if (optlen != TCPOLEN_SIGNATURE) 3198 continue; 3199 if (sigp && 3200 !consttime_memequal(sigp, cp + 2, TCP_SIGLEN)) 3201 return (-1); 3202 3203 sigp = sigbuf; 3204 memcpy(sigbuf, cp + 2, TCP_SIGLEN); 3205 tp->t_flags |= TF_SIGNATURE; 3206 break; 3207 #endif 3208 } 3209 } 3210 3211 #ifndef TCP_SIGNATURE 3212 return 0; 3213 #else 3214 if (tp->t_flags & TF_SIGNATURE) { 3215 sav = tcp_signature_getsav(m); 3216 if (sav == NULL && tp->t_state == TCPS_LISTEN) 3217 return (-1); 3218 } 3219 3220 if ((sigp ? TF_SIGNATURE : 0) ^ (tp->t_flags & TF_SIGNATURE)) 3221 goto out; 3222 3223 if (sigp) { 3224 char sig[TCP_SIGLEN]; 3225 3226 tcp_fields_to_net(th); 3227 if (tcp_signature(m, th, toff, sav, sig) < 0) { 3228 tcp_fields_to_host(th); 3229 goto out; 3230 } 3231 tcp_fields_to_host(th); 3232 3233 if (!consttime_memequal(sig, sigp, TCP_SIGLEN)) { 3234 TCP_STATINC(TCP_STAT_BADSIG); 3235 goto out; 3236 } else 3237 TCP_STATINC(TCP_STAT_GOODSIG); 3238 3239 key_sa_recordxfer(sav, m); 3240 KEY_SA_UNREF(&sav); 3241 } 3242 return 0; 3243 out: 3244 if (sav != NULL) 3245 KEY_SA_UNREF(&sav); 3246 return -1; 3247 #endif 3248 } 3249 3250 /* 3251 * Pull out of band byte out of a segment so 3252 * it doesn't appear in the user's data queue. 3253 * It is still reflected in the segment length for 3254 * sequencing purposes. 3255 */ 3256 void 3257 tcp_pulloutofband(struct socket *so, struct tcphdr *th, 3258 struct mbuf *m, int off) 3259 { 3260 int cnt = off + th->th_urp - 1; 3261 3262 while (cnt >= 0) { 3263 if (m->m_len > cnt) { 3264 char *cp = mtod(m, char *) + cnt; 3265 struct tcpcb *tp = sototcpcb(so); 3266 3267 tp->t_iobc = *cp; 3268 tp->t_oobflags |= TCPOOB_HAVEDATA; 3269 memmove(cp, cp + 1, (unsigned)(m->m_len - cnt - 1)); 3270 m->m_len--; 3271 return; 3272 } 3273 cnt -= m->m_len; 3274 m = m->m_next; 3275 if (m == NULL) 3276 break; 3277 } 3278 panic("tcp_pulloutofband"); 3279 } 3280 3281 /* 3282 * Collect new round-trip time estimate 3283 * and update averages and current timeout. 3284 * 3285 * rtt is in units of slow ticks (typically 500 ms) -- essentially the 3286 * difference of two timestamps. 3287 */ 3288 void 3289 tcp_xmit_timer(struct tcpcb *tp, uint32_t rtt) 3290 { 3291 int32_t delta; 3292 3293 TCP_STATINC(TCP_STAT_RTTUPDATED); 3294 if (tp->t_srtt != 0) { 3295 /* 3296 * Compute the amount to add to srtt for smoothing, 3297 * *alpha, or 2^(-TCP_RTT_SHIFT). Because 3298 * srtt is stored in 1/32 slow ticks, we conceptually 3299 * shift left 5 bits, subtract srtt to get the 3300 * difference, and then shift right by TCP_RTT_SHIFT 3301 * (3) to obtain 1/8 of the difference. 3302 */ 3303 delta = (rtt << 2) - (tp->t_srtt >> TCP_RTT_SHIFT); 3304 /* 3305 * This can never happen, because delta's lowest 3306 * possible value is 1/8 of t_srtt. But if it does, 3307 * set srtt to some reasonable value, here chosen 3308 * as 1/8 tick. 3309 */ 3310 if ((tp->t_srtt += delta) <= 0) 3311 tp->t_srtt = 1 << 2; 3312 /* 3313 * RFC2988 requires that rttvar be updated first. 3314 * This code is compliant because "delta" is the old 3315 * srtt minus the new observation (scaled). 3316 * 3317 * RFC2988 says: 3318 * rttvar = (1-beta) * rttvar + beta * |srtt-observed| 3319 * 3320 * delta is in units of 1/32 ticks, and has then been 3321 * divided by 8. This is equivalent to being in 1/16s 3322 * units and divided by 4. Subtract from it 1/4 of 3323 * the existing rttvar to form the (signed) amount to 3324 * adjust. 3325 */ 3326 if (delta < 0) 3327 delta = -delta; 3328 delta -= (tp->t_rttvar >> TCP_RTTVAR_SHIFT); 3329 /* 3330 * As with srtt, this should never happen. There is 3331 * no support in RFC2988 for this operation. But 1/4s 3332 * as rttvar when faced with something arguably wrong 3333 * is ok. 3334 */ 3335 if ((tp->t_rttvar += delta) <= 0) 3336 tp->t_rttvar = 1 << 2; 3337 3338 /* 3339 * If srtt exceeds .01 second, ensure we use the 'remote' MSL 3340 * Problem is: it doesn't work. Disabled by defaulting 3341 * tcp_rttlocal to 0; see corresponding code in 3342 * tcp_subr that selects local vs remote in a different way. 3343 * 3344 * The static branch prediction hint here should be removed 3345 * when the rtt estimator is fixed and the rtt_enable code 3346 * is turned back on. 3347 */ 3348 if (__predict_false(tcp_rttlocal) && tcp_msl_enable 3349 && tp->t_srtt > tcp_msl_remote_threshold 3350 && tp->t_msl < tcp_msl_remote) { 3351 tp->t_msl = MIN(tcp_msl_remote, TCP_MAXMSL); 3352 } 3353 } else { 3354 /* 3355 * This is the first measurement. Per RFC2988, 2.2, 3356 * set rtt=R and srtt=R/2. 3357 * For srtt, storage representation is 1/32 ticks, 3358 * so shift left by 5. 3359 * For rttvar, storage representation is 1/16 ticks, 3360 * So shift left by 4, but then right by 1 to halve. 3361 */ 3362 tp->t_srtt = rtt << (TCP_RTT_SHIFT + 2); 3363 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT + 2 - 1); 3364 } 3365 tp->t_rtttime = 0; 3366 tp->t_rxtshift = 0; 3367 3368 /* 3369 * the retransmit should happen at rtt + 4 * rttvar. 3370 * Because of the way we do the smoothing, srtt and rttvar 3371 * will each average +1/2 tick of bias. When we compute 3372 * the retransmit timer, we want 1/2 tick of rounding and 3373 * 1 extra tick because of +-1/2 tick uncertainty in the 3374 * firing of the timer. The bias will give us exactly the 3375 * 1.5 tick we need. But, because the bias is 3376 * statistical, we have to test that we don't drop below 3377 * the minimum feasible timer (which is 2 ticks). 3378 */ 3379 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), 3380 uimax(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX); 3381 3382 /* 3383 * We received an ack for a packet that wasn't retransmitted; 3384 * it is probably safe to discard any error indications we've 3385 * received recently. This isn't quite right, but close enough 3386 * for now (a route might have failed after we sent a segment, 3387 * and the return path might not be symmetrical). 3388 */ 3389 tp->t_softerror = 0; 3390 } 3391
Indexes created Tue Sep 23 14:10:03 GMT 2025