tcp_input.c revision 1.438
1 /* $NetBSD: tcp_input.c,v 1.438 2022/11/04 09:01:53 ozaki-r 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 1.438 2022/11/04 09:01:53 ozaki-r 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 uint64_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 tcps[TCP_STAT_RCVDUPPACK]++; 589 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 tcps[TCP_STAT_RCVOOPACK]++; 732 tcps[TCP_STAT_RCVOOBYTE] += rcvoobyte; 733 if (rcvpartdupbyte) { 734 tcps[TCP_STAT_RCVPARTDUPPACK]++; 735 tcps[TCP_STAT_RCVPARTDUPBYTE] += rcvpartdupbyte; 736 } 737 TCP_STAT_PUTREF(); 738 739 /* 740 * Insert the new fragment queue entry into both queues. 741 */ 742 tiqe->ipqe_m = m; 743 tiqe->ipqe_seq = pkt_seq; 744 tiqe->ipqe_len = pkt_len; 745 tiqe->ipqe_flags = pkt_flags; 746 if (p == NULL) { 747 TAILQ_INSERT_HEAD(&tp->segq, tiqe, ipqe_q); 748 } else { 749 TAILQ_INSERT_AFTER(&tp->segq, p, tiqe, ipqe_q); 750 } 751 tp->t_segqlen++; 752 753 skip_replacement: 754 TAILQ_INSERT_HEAD(&tp->timeq, tiqe, ipqe_timeq); 755 756 present: 757 /* 758 * Present data to user, advancing rcv_nxt through 759 * completed sequence space. 760 */ 761 if (TCPS_HAVEESTABLISHED(tp->t_state) == 0) 762 goto out; 763 q = TAILQ_FIRST(&tp->segq); 764 if (q == NULL || q->ipqe_seq != tp->rcv_nxt) 765 goto out; 766 if (tp->t_state == TCPS_SYN_RECEIVED && q->ipqe_len) 767 goto out; 768 769 tp->rcv_nxt += q->ipqe_len; 770 pkt_flags = q->ipqe_flags & TH_FIN; 771 nd_hint(tp); 772 773 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 774 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 775 tp->t_segqlen--; 776 KASSERT(tp->t_segqlen >= 0); 777 KASSERT(tp->t_segqlen != 0 || 778 (TAILQ_EMPTY(&tp->segq) && TAILQ_EMPTY(&tp->timeq))); 779 if (so->so_state & SS_CANTRCVMORE) 780 m_freem(q->ipqe_m); 781 else 782 sbappendstream(&so->so_rcv, q->ipqe_m); 783 tcpipqent_free(q); 784 TCP_REASS_UNLOCK(tp); 785 sorwakeup(so); 786 return pkt_flags; 787 788 out: 789 TCP_REASS_UNLOCK(tp); 790 return 0; 791 } 792 793 #ifdef INET6 794 int 795 tcp6_input(struct mbuf **mp, int *offp, int proto) 796 { 797 struct mbuf *m = *mp; 798 799 /* 800 * draft-itojun-ipv6-tcp-to-anycast 801 * better place to put this in? 802 */ 803 if (m->m_flags & M_ANYCAST6) { 804 struct ip6_hdr *ip6; 805 if (m->m_len < sizeof(struct ip6_hdr)) { 806 if ((m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) { 807 TCP_STATINC(TCP_STAT_RCVSHORT); 808 return IPPROTO_DONE; 809 } 810 } 811 ip6 = mtod(m, struct ip6_hdr *); 812 icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR, 813 (char *)&ip6->ip6_dst - (char *)ip6); 814 return IPPROTO_DONE; 815 } 816 817 tcp_input(m, *offp, proto); 818 return IPPROTO_DONE; 819 } 820 #endif 821 822 static void 823 tcp4_log_refused(const struct ip *ip, const struct tcphdr *th) 824 { 825 char src[INET_ADDRSTRLEN]; 826 char dst[INET_ADDRSTRLEN]; 827 828 if (ip) { 829 in_print(src, sizeof(src), &ip->ip_src); 830 in_print(dst, sizeof(dst), &ip->ip_dst); 831 } else { 832 strlcpy(src, "(unknown)", sizeof(src)); 833 strlcpy(dst, "(unknown)", sizeof(dst)); 834 } 835 log(LOG_INFO, 836 "Connection attempt to TCP %s:%d from %s:%d\n", 837 dst, ntohs(th->th_dport), 838 src, ntohs(th->th_sport)); 839 } 840 841 #ifdef INET6 842 static void 843 tcp6_log_refused(const struct ip6_hdr *ip6, const struct tcphdr *th) 844 { 845 char src[INET6_ADDRSTRLEN]; 846 char dst[INET6_ADDRSTRLEN]; 847 848 if (ip6) { 849 in6_print(src, sizeof(src), &ip6->ip6_src); 850 in6_print(dst, sizeof(dst), &ip6->ip6_dst); 851 } else { 852 strlcpy(src, "(unknown v6)", sizeof(src)); 853 strlcpy(dst, "(unknown v6)", sizeof(dst)); 854 } 855 log(LOG_INFO, 856 "Connection attempt to TCP [%s]:%d from [%s]:%d\n", 857 dst, ntohs(th->th_dport), 858 src, ntohs(th->th_sport)); 859 } 860 #endif 861 862 /* 863 * Checksum extended TCP header and data. 864 */ 865 int 866 tcp_input_checksum(int af, struct mbuf *m, const struct tcphdr *th, 867 int toff, int off, int tlen) 868 { 869 struct ifnet *rcvif; 870 int s; 871 872 /* 873 * XXX it's better to record and check if this mbuf is 874 * already checked. 875 */ 876 877 rcvif = m_get_rcvif(m, &s); 878 if (__predict_false(rcvif == NULL)) 879 goto badcsum; /* XXX */ 880 881 switch (af) { 882 case AF_INET: 883 switch (m->m_pkthdr.csum_flags & 884 ((rcvif->if_csum_flags_rx & M_CSUM_TCPv4) | 885 M_CSUM_TCP_UDP_BAD | M_CSUM_DATA)) { 886 case M_CSUM_TCPv4|M_CSUM_TCP_UDP_BAD: 887 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_bad); 888 goto badcsum; 889 890 case M_CSUM_TCPv4|M_CSUM_DATA: { 891 u_int32_t hw_csum = m->m_pkthdr.csum_data; 892 893 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_data); 894 if (m->m_pkthdr.csum_flags & M_CSUM_NO_PSEUDOHDR) { 895 const struct ip *ip = 896 mtod(m, const struct ip *); 897 898 hw_csum = in_cksum_phdr(ip->ip_src.s_addr, 899 ip->ip_dst.s_addr, 900 htons(hw_csum + tlen + off + IPPROTO_TCP)); 901 } 902 if ((hw_csum ^ 0xffff) != 0) 903 goto badcsum; 904 break; 905 } 906 907 case M_CSUM_TCPv4: 908 /* Checksum was okay. */ 909 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_ok); 910 break; 911 912 default: 913 /* 914 * Must compute it ourselves. Maybe skip checksum 915 * on loopback interfaces. 916 */ 917 if (__predict_true(!(rcvif->if_flags & IFF_LOOPBACK) || 918 tcp_do_loopback_cksum)) { 919 TCP_CSUM_COUNTER_INCR(&tcp_swcsum); 920 if (in4_cksum(m, IPPROTO_TCP, toff, 921 tlen + off) != 0) 922 goto badcsum; 923 } 924 break; 925 } 926 break; 927 928 #ifdef INET6 929 case AF_INET6: 930 switch (m->m_pkthdr.csum_flags & 931 ((rcvif->if_csum_flags_rx & M_CSUM_TCPv6) | 932 M_CSUM_TCP_UDP_BAD | M_CSUM_DATA)) { 933 case M_CSUM_TCPv6|M_CSUM_TCP_UDP_BAD: 934 TCP_CSUM_COUNTER_INCR(&tcp6_hwcsum_bad); 935 goto badcsum; 936 937 #if 0 /* notyet */ 938 case M_CSUM_TCPv6|M_CSUM_DATA: 939 #endif 940 941 case M_CSUM_TCPv6: 942 /* Checksum was okay. */ 943 TCP_CSUM_COUNTER_INCR(&tcp6_hwcsum_ok); 944 break; 945 946 default: 947 /* 948 * Must compute it ourselves. Maybe skip checksum 949 * on loopback interfaces. 950 */ 951 if (__predict_true((m->m_flags & M_LOOP) == 0 || 952 tcp_do_loopback_cksum)) { 953 TCP_CSUM_COUNTER_INCR(&tcp6_swcsum); 954 if (in6_cksum(m, IPPROTO_TCP, toff, 955 tlen + off) != 0) 956 goto badcsum; 957 } 958 } 959 break; 960 #endif /* INET6 */ 961 } 962 m_put_rcvif(rcvif, &s); 963 964 return 0; 965 966 badcsum: 967 m_put_rcvif(rcvif, &s); 968 TCP_STATINC(TCP_STAT_RCVBADSUM); 969 return -1; 970 } 971 972 /* 973 * When a packet arrives addressed to a vestigial tcpbp, we 974 * nevertheless have to respond to it per the spec. 975 * 976 * This code is duplicated from the one in tcp_input(). 977 */ 978 static void tcp_vtw_input(struct tcphdr *th, vestigial_inpcb_t *vp, 979 struct mbuf *m, int tlen) 980 { 981 int tiflags; 982 int todrop; 983 uint32_t t_flags = 0; 984 uint64_t *tcps; 985 986 tiflags = th->th_flags; 987 todrop = vp->rcv_nxt - th->th_seq; 988 989 if (todrop > 0) { 990 if (tiflags & TH_SYN) { 991 tiflags &= ~TH_SYN; 992 th->th_seq++; 993 tcp_urp_drop(th, 1, &tiflags); 994 todrop--; 995 } 996 if (todrop > tlen || 997 (todrop == tlen && (tiflags & TH_FIN) == 0)) { 998 /* 999 * Any valid FIN or RST must be to the left of the 1000 * window. At this point the FIN or RST must be a 1001 * duplicate or out of sequence; drop it. 1002 */ 1003 if (tiflags & TH_RST) 1004 goto drop; 1005 tiflags &= ~(TH_FIN|TH_RST); 1006 1007 /* 1008 * Send an ACK to resynchronize and drop any data. 1009 * But keep on processing for RST or ACK. 1010 */ 1011 t_flags |= TF_ACKNOW; 1012 todrop = tlen; 1013 tcps = TCP_STAT_GETREF(); 1014 tcps[TCP_STAT_RCVDUPPACK] += 1; 1015 tcps[TCP_STAT_RCVDUPBYTE] += todrop; 1016 TCP_STAT_PUTREF(); 1017 } else if ((tiflags & TH_RST) && 1018 th->th_seq != vp->rcv_nxt) { 1019 /* 1020 * Test for reset before adjusting the sequence 1021 * number for overlapping data. 1022 */ 1023 goto dropafterack_ratelim; 1024 } else { 1025 tcps = TCP_STAT_GETREF(); 1026 tcps[TCP_STAT_RCVPARTDUPPACK] += 1; 1027 tcps[TCP_STAT_RCVPARTDUPBYTE] += todrop; 1028 TCP_STAT_PUTREF(); 1029 } 1030 1031 // tcp_new_dsack(tp, th->th_seq, todrop); 1032 // hdroptlen += todrop; /*drop from head afterwards*/ 1033 1034 th->th_seq += todrop; 1035 tlen -= todrop; 1036 tcp_urp_drop(th, todrop, &tiflags); 1037 } 1038 1039 /* 1040 * If new data are received on a connection after the 1041 * user processes are gone, then RST the other end. 1042 */ 1043 if (tlen) { 1044 TCP_STATINC(TCP_STAT_RCVAFTERCLOSE); 1045 goto dropwithreset; 1046 } 1047 1048 /* 1049 * If segment ends after window, drop trailing data 1050 * (and PUSH and FIN); if nothing left, just ACK. 1051 */ 1052 todrop = (th->th_seq + tlen) - (vp->rcv_nxt + vp->rcv_wnd); 1053 1054 if (todrop > 0) { 1055 TCP_STATINC(TCP_STAT_RCVPACKAFTERWIN); 1056 if (todrop >= tlen) { 1057 /* 1058 * The segment actually starts after the window. 1059 * th->th_seq + tlen - vp->rcv_nxt - vp->rcv_wnd >= tlen 1060 * th->th_seq - vp->rcv_nxt - vp->rcv_wnd >= 0 1061 * th->th_seq >= vp->rcv_nxt + vp->rcv_wnd 1062 */ 1063 TCP_STATADD(TCP_STAT_RCVBYTEAFTERWIN, tlen); 1064 1065 /* 1066 * If a new connection request is received 1067 * while in TIME_WAIT, drop the old connection 1068 * and start over if the sequence numbers 1069 * are above the previous ones. 1070 */ 1071 if ((tiflags & TH_SYN) && 1072 SEQ_GT(th->th_seq, vp->rcv_nxt)) { 1073 /* 1074 * We only support this in the !NOFDREF case, which 1075 * is to say: not here. 1076 */ 1077 goto dropwithreset; 1078 } 1079 1080 /* 1081 * If window is closed can only take segments at 1082 * window edge, and have to drop data and PUSH from 1083 * incoming segments. Continue processing, but 1084 * remember to ack. Otherwise, drop segment 1085 * and (if not RST) ack. 1086 */ 1087 if (vp->rcv_wnd == 0 && th->th_seq == vp->rcv_nxt) { 1088 t_flags |= TF_ACKNOW; 1089 TCP_STATINC(TCP_STAT_RCVWINPROBE); 1090 } else { 1091 goto dropafterack; 1092 } 1093 } else { 1094 TCP_STATADD(TCP_STAT_RCVBYTEAFTERWIN, todrop); 1095 } 1096 m_adj(m, -todrop); 1097 tlen -= todrop; 1098 tiflags &= ~(TH_PUSH|TH_FIN); 1099 } 1100 1101 if (tiflags & TH_RST) { 1102 if (th->th_seq != vp->rcv_nxt) 1103 goto dropafterack_ratelim; 1104 1105 vtw_del(vp->ctl, vp->vtw); 1106 goto drop; 1107 } 1108 1109 /* 1110 * If the ACK bit is off we drop the segment and return. 1111 */ 1112 if ((tiflags & TH_ACK) == 0) { 1113 if (t_flags & TF_ACKNOW) 1114 goto dropafterack; 1115 goto drop; 1116 } 1117 1118 /* 1119 * In TIME_WAIT state the only thing that should arrive 1120 * is a retransmission of the remote FIN. Acknowledge 1121 * it and restart the finack timer. 1122 */ 1123 vtw_restart(vp); 1124 goto dropafterack; 1125 1126 dropafterack: 1127 /* 1128 * Generate an ACK dropping incoming segment if it occupies 1129 * sequence space, where the ACK reflects our state. 1130 */ 1131 if (tiflags & TH_RST) 1132 goto drop; 1133 goto dropafterack2; 1134 1135 dropafterack_ratelim: 1136 /* 1137 * We may want to rate-limit ACKs against SYN/RST attack. 1138 */ 1139 if (ppsratecheck(&tcp_ackdrop_ppslim_last, &tcp_ackdrop_ppslim_count, 1140 tcp_ackdrop_ppslim) == 0) { 1141 /* XXX stat */ 1142 goto drop; 1143 } 1144 /* ...fall into dropafterack2... */ 1145 1146 dropafterack2: 1147 (void)tcp_respond(0, m, m, th, th->th_seq + tlen, th->th_ack, TH_ACK); 1148 return; 1149 1150 dropwithreset: 1151 /* 1152 * Generate a RST, dropping incoming segment. 1153 * Make ACK acceptable to originator of segment. 1154 */ 1155 if (tiflags & TH_RST) 1156 goto drop; 1157 1158 if (tiflags & TH_ACK) { 1159 tcp_respond(0, m, m, th, (tcp_seq)0, th->th_ack, TH_RST); 1160 } else { 1161 if (tiflags & TH_SYN) 1162 ++tlen; 1163 (void)tcp_respond(0, m, m, th, th->th_seq + tlen, (tcp_seq)0, 1164 TH_RST|TH_ACK); 1165 } 1166 return; 1167 drop: 1168 m_freem(m); 1169 } 1170 1171 /* 1172 * TCP input routine, follows pages 65-76 of RFC 793 very closely. 1173 */ 1174 void 1175 tcp_input(struct mbuf *m, int off, int proto) 1176 { 1177 struct tcphdr *th; 1178 struct ip *ip; 1179 struct inpcb *inp; 1180 #ifdef INET6 1181 struct ip6_hdr *ip6; 1182 #endif 1183 u_int8_t *optp = NULL; 1184 int optlen = 0; 1185 int len, tlen, hdroptlen = 0; 1186 struct tcpcb *tp = NULL; 1187 int tiflags; 1188 struct socket *so = NULL; 1189 int todrop, acked, ourfinisacked, needoutput = 0; 1190 bool dupseg; 1191 #ifdef TCP_DEBUG 1192 short ostate = 0; 1193 #endif 1194 u_long tiwin; 1195 struct tcp_opt_info opti; 1196 int thlen, iphlen; 1197 int af; /* af on the wire */ 1198 struct mbuf *tcp_saveti = NULL; 1199 uint32_t ts_rtt; 1200 uint8_t iptos; 1201 uint64_t *tcps; 1202 vestigial_inpcb_t vestige; 1203 1204 vestige.valid = 0; 1205 1206 MCLAIM(m, &tcp_rx_mowner); 1207 1208 TCP_STATINC(TCP_STAT_RCVTOTAL); 1209 1210 memset(&opti, 0, sizeof(opti)); 1211 opti.ts_present = 0; 1212 opti.maxseg = 0; 1213 1214 /* 1215 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN. 1216 * 1217 * TCP is, by definition, unicast, so we reject all 1218 * multicast outright. 1219 * 1220 * Note, there are additional src/dst address checks in 1221 * the AF-specific code below. 1222 */ 1223 if (m->m_flags & (M_BCAST|M_MCAST)) { 1224 /* XXX stat */ 1225 goto drop; 1226 } 1227 #ifdef INET6 1228 if (m->m_flags & M_ANYCAST6) { 1229 /* XXX stat */ 1230 goto drop; 1231 } 1232 #endif 1233 1234 M_REGION_GET(th, struct tcphdr *, m, off, sizeof(struct tcphdr)); 1235 if (th == NULL) { 1236 TCP_STATINC(TCP_STAT_RCVSHORT); 1237 return; 1238 } 1239 1240 /* 1241 * Enforce alignment requirements that are violated in 1242 * some cases, see kern/50766 for details. 1243 */ 1244 if (ACCESSIBLE_POINTER(th, struct tcphdr) == 0) { 1245 m = m_copyup(m, off + sizeof(struct tcphdr), 0); 1246 if (m == NULL) { 1247 TCP_STATINC(TCP_STAT_RCVSHORT); 1248 return; 1249 } 1250 th = (struct tcphdr *)(mtod(m, char *) + off); 1251 } 1252 KASSERT(ACCESSIBLE_POINTER(th, struct tcphdr)); 1253 1254 /* 1255 * Get IP and TCP header. 1256 * Note: IP leaves IP header in first mbuf. 1257 */ 1258 ip = mtod(m, struct ip *); 1259 #ifdef INET6 1260 ip6 = mtod(m, struct ip6_hdr *); 1261 #endif 1262 switch (ip->ip_v) { 1263 case 4: 1264 af = AF_INET; 1265 iphlen = sizeof(struct ip); 1266 1267 if (IN_MULTICAST(ip->ip_dst.s_addr) || 1268 in_broadcast(ip->ip_dst, m_get_rcvif_NOMPSAFE(m))) 1269 goto drop; 1270 1271 /* We do the checksum after PCB lookup... */ 1272 len = ntohs(ip->ip_len); 1273 tlen = len - off; 1274 iptos = ip->ip_tos; 1275 break; 1276 #ifdef INET6 1277 case 6: 1278 iphlen = sizeof(struct ip6_hdr); 1279 af = AF_INET6; 1280 1281 /* 1282 * Be proactive about unspecified IPv6 address in source. 1283 * As we use all-zero to indicate unbounded/unconnected pcb, 1284 * unspecified IPv6 address can be used to confuse us. 1285 * 1286 * Note that packets with unspecified IPv6 destination is 1287 * already dropped in ip6_input. 1288 */ 1289 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 1290 /* XXX stat */ 1291 goto drop; 1292 } 1293 1294 /* 1295 * Make sure destination address is not multicast. 1296 * Source address checked in ip6_input(). 1297 */ 1298 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) { 1299 /* XXX stat */ 1300 goto drop; 1301 } 1302 1303 /* We do the checksum after PCB lookup... */ 1304 len = m->m_pkthdr.len; 1305 tlen = len - off; 1306 iptos = (ntohl(ip6->ip6_flow) >> 20) & 0xff; 1307 break; 1308 #endif 1309 default: 1310 m_freem(m); 1311 return; 1312 } 1313 1314 1315 /* 1316 * Check that TCP offset makes sense, pull out TCP options and 1317 * adjust length. 1318 */ 1319 thlen = th->th_off << 2; 1320 if (thlen < sizeof(struct tcphdr) || thlen > tlen) { 1321 TCP_STATINC(TCP_STAT_RCVBADOFF); 1322 goto drop; 1323 } 1324 tlen -= thlen; 1325 1326 if (thlen > sizeof(struct tcphdr)) { 1327 M_REGION_GET(th, struct tcphdr *, m, off, thlen); 1328 if (th == NULL) { 1329 TCP_STATINC(TCP_STAT_RCVSHORT); 1330 return; 1331 } 1332 KASSERT(ACCESSIBLE_POINTER(th, struct tcphdr)); 1333 optlen = thlen - sizeof(struct tcphdr); 1334 optp = ((u_int8_t *)th) + sizeof(struct tcphdr); 1335 1336 /* 1337 * Do quick retrieval of timestamp options. 1338 * 1339 * If timestamp is the only option and it's formatted as 1340 * recommended in RFC 1323 appendix A, we quickly get the 1341 * values now and don't bother calling tcp_dooptions(), 1342 * etc. 1343 */ 1344 if ((optlen == TCPOLEN_TSTAMP_APPA || 1345 (optlen > TCPOLEN_TSTAMP_APPA && 1346 optp[TCPOLEN_TSTAMP_APPA] == TCPOPT_EOL)) && 1347 be32dec(optp) == TCPOPT_TSTAMP_HDR && 1348 (th->th_flags & TH_SYN) == 0) { 1349 opti.ts_present = 1; 1350 opti.ts_val = be32dec(optp + 4); 1351 opti.ts_ecr = be32dec(optp + 8); 1352 optp = NULL; /* we've parsed the options */ 1353 } 1354 } 1355 tiflags = th->th_flags; 1356 1357 /* 1358 * Checksum extended TCP header and data 1359 */ 1360 if (tcp_input_checksum(af, m, th, off, thlen, tlen)) 1361 goto badcsum; 1362 1363 /* 1364 * Locate pcb for segment. 1365 */ 1366 findpcb: 1367 inp = NULL; 1368 switch (af) { 1369 case AF_INET: 1370 inp = inpcb_lookup(&tcbtable, ip->ip_src, th->th_sport, 1371 ip->ip_dst, th->th_dport, &vestige); 1372 if (inp == NULL && !vestige.valid) { 1373 TCP_STATINC(TCP_STAT_PCBHASHMISS); 1374 inp = inpcb_lookup_bound(&tcbtable, ip->ip_dst, 1375 th->th_dport); 1376 } 1377 #ifdef INET6 1378 if (inp == NULL && !vestige.valid) { 1379 struct in6_addr s, d; 1380 1381 /* mapped addr case */ 1382 in6_in_2_v4mapin6(&ip->ip_src, &s); 1383 in6_in_2_v4mapin6(&ip->ip_dst, &d); 1384 inp = in6pcb_lookup(&tcbtable, &s, 1385 th->th_sport, &d, th->th_dport, 0, &vestige); 1386 if (inp == NULL && !vestige.valid) { 1387 TCP_STATINC(TCP_STAT_PCBHASHMISS); 1388 inp = in6pcb_lookup_bound(&tcbtable, &d, 1389 th->th_dport, 0); 1390 } 1391 } 1392 #endif 1393 if (inp == NULL && !vestige.valid) { 1394 TCP_STATINC(TCP_STAT_NOPORT); 1395 if (tcp_log_refused && 1396 (tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) { 1397 tcp4_log_refused(ip, th); 1398 } 1399 tcp_fields_to_host(th); 1400 goto dropwithreset_ratelim; 1401 } 1402 #if defined(IPSEC) 1403 if (ipsec_used) { 1404 if (inp && ipsec_in_reject(m, inp)) 1405 goto drop; 1406 } 1407 #endif /*IPSEC*/ 1408 break; 1409 #ifdef INET6 1410 case AF_INET6: 1411 { 1412 int faith; 1413 1414 #if defined(NFAITH) && NFAITH > 0 1415 faith = faithprefix(&ip6->ip6_dst); 1416 #else 1417 faith = 0; 1418 #endif 1419 inp = in6pcb_lookup(&tcbtable, &ip6->ip6_src, 1420 th->th_sport, &ip6->ip6_dst, th->th_dport, faith, &vestige); 1421 if (inp == NULL && !vestige.valid) { 1422 TCP_STATINC(TCP_STAT_PCBHASHMISS); 1423 inp = in6pcb_lookup_bound(&tcbtable, &ip6->ip6_dst, 1424 th->th_dport, faith); 1425 } 1426 if (inp == NULL && !vestige.valid) { 1427 TCP_STATINC(TCP_STAT_NOPORT); 1428 if (tcp_log_refused && 1429 (tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) { 1430 tcp6_log_refused(ip6, th); 1431 } 1432 tcp_fields_to_host(th); 1433 goto dropwithreset_ratelim; 1434 } 1435 #if defined(IPSEC) 1436 if (ipsec_used && inp && ipsec_in_reject(m, inp)) 1437 goto drop; 1438 #endif 1439 break; 1440 } 1441 #endif 1442 } 1443 1444 tcp_fields_to_host(th); 1445 1446 /* 1447 * If the state is CLOSED (i.e., TCB does not exist) then 1448 * all data in the incoming segment is discarded. 1449 * If the TCB exists but is in CLOSED state, it is embryonic, 1450 * but should either do a listen or a connect soon. 1451 */ 1452 tp = NULL; 1453 so = NULL; 1454 if (inp) { 1455 /* Check the minimum TTL for socket. */ 1456 if (inp->inp_af == AF_INET && ip->ip_ttl < in4p_ip_minttl(inp)) 1457 goto drop; 1458 1459 tp = intotcpcb(inp); 1460 so = inp->inp_socket; 1461 } else if (vestige.valid) { 1462 /* We do not support the resurrection of vtw tcpcps. */ 1463 tcp_vtw_input(th, &vestige, m, tlen); 1464 m = NULL; 1465 goto drop; 1466 } 1467 1468 if (tp == NULL) 1469 goto dropwithreset_ratelim; 1470 if (tp->t_state == TCPS_CLOSED) 1471 goto drop; 1472 1473 KASSERT(so->so_lock == softnet_lock); 1474 KASSERT(solocked(so)); 1475 1476 /* Unscale the window into a 32-bit value. */ 1477 if ((tiflags & TH_SYN) == 0) 1478 tiwin = th->th_win << tp->snd_scale; 1479 else 1480 tiwin = th->th_win; 1481 1482 #ifdef INET6 1483 /* save packet options if user wanted */ 1484 if (inp->inp_af == AF_INET6 && (inp->inp_flags & IN6P_CONTROLOPTS)) { 1485 if (inp->inp_options) { 1486 m_freem(inp->inp_options); 1487 inp->inp_options = NULL; 1488 } 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 tcps[TCP_STAT_PREDACK]++; 1845 tcps[TCP_STAT_RCVACKPACK]++; 1846 tcps[TCP_STAT_RCVACKBYTE] += acked; 1847 TCP_STAT_PUTREF(); 1848 nd_hint(tp); 1849 1850 if (acked > (tp->t_lastoff - tp->t_inoff)) 1851 tp->t_lastm = NULL; 1852 sbdrop(&so->so_snd, acked); 1853 tp->t_lastoff -= acked; 1854 1855 icmp_check(tp, th, acked); 1856 1857 tp->snd_una = th->th_ack; 1858 tp->snd_fack = tp->snd_una; 1859 if (SEQ_LT(tp->snd_high, tp->snd_una)) 1860 tp->snd_high = tp->snd_una; 1861 /* 1862 * drag snd_wl2 along so only newer 1863 * ACKs can update the window size. 1864 * also avoids the state where snd_wl2 1865 * is eventually larger than th_ack and thus 1866 * blocking the window update mechanism and 1867 * the connection gets stuck for a loooong 1868 * time in the zero sized send window state. 1869 * 1870 * see PR/kern 55567 1871 */ 1872 tp->snd_wl2 = tp->snd_una; 1873 1874 m_freem(m); 1875 1876 /* 1877 * If all outstanding data are acked, stop 1878 * retransmit timer, otherwise restart timer 1879 * using current (possibly backed-off) value. 1880 * If process is waiting for space, 1881 * wakeup/selnotify/signal. If data 1882 * are ready to send, let tcp_output 1883 * decide between more output or persist. 1884 */ 1885 if (tp->snd_una == tp->snd_max) 1886 TCP_TIMER_DISARM(tp, TCPT_REXMT); 1887 else if (TCP_TIMER_ISARMED(tp, 1888 TCPT_PERSIST) == 0) 1889 TCP_TIMER_ARM(tp, TCPT_REXMT, 1890 tp->t_rxtcur); 1891 1892 sowwakeup(so); 1893 if (so->so_snd.sb_cc) { 1894 KERNEL_LOCK(1, NULL); 1895 (void)tcp_output(tp); 1896 KERNEL_UNLOCK_ONE(NULL); 1897 } 1898 if (tcp_saveti) 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 tcps[TCP_STAT_PREDDAT]++; 1928 tcps[TCP_STAT_RCVPACK]++; 1929 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 if (tcp_saveti) 2010 m_freem(tcp_saveti); 2011 return; 2012 } 2013 } 2014 2015 /* 2016 * Compute mbuf offset to TCP data segment. 2017 */ 2018 hdroptlen = off + thlen; 2019 2020 /* 2021 * Calculate amount of space in receive window. Receive window is 2022 * amount of space in rcv queue, but not less than advertised 2023 * window. 2024 */ 2025 { 2026 int win; 2027 win = sbspace(&so->so_rcv); 2028 if (win < 0) 2029 win = 0; 2030 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 2031 } 2032 2033 /* Reset receive buffer auto scaling when not in bulk receive mode. */ 2034 tp->rfbuf_ts = 0; 2035 tp->rfbuf_cnt = 0; 2036 2037 switch (tp->t_state) { 2038 /* 2039 * If the state is SYN_SENT: 2040 * if seg contains an ACK, but not for our SYN, drop the input. 2041 * if seg contains a RST, then drop the connection. 2042 * if seg does not contain SYN, then drop it. 2043 * Otherwise this is an acceptable SYN segment 2044 * initialize tp->rcv_nxt and tp->irs 2045 * if seg contains ack then advance tp->snd_una 2046 * if seg contains a ECE and ECN support is enabled, the stream 2047 * is ECN capable. 2048 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 2049 * arrange for segment to be acked (eventually) 2050 * continue processing rest of data/controls, beginning with URG 2051 */ 2052 case TCPS_SYN_SENT: 2053 if ((tiflags & TH_ACK) && 2054 (SEQ_LEQ(th->th_ack, tp->iss) || 2055 SEQ_GT(th->th_ack, tp->snd_max))) 2056 goto dropwithreset; 2057 if (tiflags & TH_RST) { 2058 if (tiflags & TH_ACK) 2059 tp = tcp_drop(tp, ECONNREFUSED); 2060 goto drop; 2061 } 2062 if ((tiflags & TH_SYN) == 0) 2063 goto drop; 2064 if (tiflags & TH_ACK) { 2065 tp->snd_una = th->th_ack; 2066 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2067 tp->snd_nxt = tp->snd_una; 2068 if (SEQ_LT(tp->snd_high, tp->snd_una)) 2069 tp->snd_high = tp->snd_una; 2070 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2071 2072 if ((tiflags & TH_ECE) && tcp_do_ecn) { 2073 tp->t_flags |= TF_ECN_PERMIT; 2074 TCP_STATINC(TCP_STAT_ECN_SHS); 2075 } 2076 } 2077 tp->irs = th->th_seq; 2078 tcp_rcvseqinit(tp); 2079 tp->t_flags |= TF_ACKNOW; 2080 tcp_mss_from_peer(tp, opti.maxseg); 2081 2082 /* 2083 * Initialize the initial congestion window. If we 2084 * had to retransmit the SYN, we must initialize cwnd 2085 * to 1 segment (i.e. the Loss Window). 2086 */ 2087 if (tp->t_flags & TF_SYN_REXMT) 2088 tp->snd_cwnd = tp->t_peermss; 2089 else { 2090 int ss = tcp_init_win; 2091 if (inp->inp_af == AF_INET && in_localaddr(in4p_faddr(inp))) 2092 ss = tcp_init_win_local; 2093 #ifdef INET6 2094 else if (inp->inp_af == AF_INET6 && in6_localaddr(&in6p_faddr(inp))) 2095 ss = tcp_init_win_local; 2096 #endif 2097 tp->snd_cwnd = TCP_INITIAL_WINDOW(ss, tp->t_peermss); 2098 } 2099 2100 tcp_rmx_rtt(tp); 2101 if (tiflags & TH_ACK) { 2102 TCP_STATINC(TCP_STAT_CONNECTS); 2103 /* 2104 * move tcp_established before soisconnected 2105 * because upcall handler can drive tcp_output 2106 * functionality. 2107 * XXX we might call soisconnected at the end of 2108 * all processing 2109 */ 2110 tcp_established(tp); 2111 soisconnected(so); 2112 /* Do window scaling on this connection? */ 2113 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2114 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2115 tp->snd_scale = tp->requested_s_scale; 2116 tp->rcv_scale = tp->request_r_scale; 2117 } 2118 TCP_REASS_LOCK(tp); 2119 (void)tcp_reass(tp, NULL, NULL, tlen); 2120 /* 2121 * if we didn't have to retransmit the SYN, 2122 * use its rtt as our initial srtt & rtt var. 2123 */ 2124 if (tp->t_rtttime) 2125 tcp_xmit_timer(tp, tcp_now - tp->t_rtttime); 2126 } else { 2127 tp->t_state = TCPS_SYN_RECEIVED; 2128 } 2129 2130 /* 2131 * Advance th->th_seq to correspond to first data byte. 2132 * If data, trim to stay within window, 2133 * dropping FIN if necessary. 2134 */ 2135 th->th_seq++; 2136 if (tlen > tp->rcv_wnd) { 2137 todrop = tlen - tp->rcv_wnd; 2138 m_adj(m, -todrop); 2139 tlen = tp->rcv_wnd; 2140 tiflags &= ~TH_FIN; 2141 tcps = TCP_STAT_GETREF(); 2142 tcps[TCP_STAT_RCVPACKAFTERWIN]++; 2143 tcps[TCP_STAT_RCVBYTEAFTERWIN] += 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 tcps[TCP_STAT_RCVDUPPACK]++; 2192 tcps[TCP_STAT_RCVDUPBYTE] += tlen; 2193 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 tcps[TCP_STAT_RCVDUPPACK]++; 2234 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 tcps[TCP_STAT_RCVPARTDUPPACK]++; 2245 tcps[TCP_STAT_RCVPARTDUPBYTE] += todrop; 2246 TCP_STAT_PUTREF(); 2247 } 2248 tcp_new_dsack(tp, th->th_seq, todrop); 2249 hdroptlen += todrop; /* drop from head afterwards (m_adj) */ 2250 th->th_seq += todrop; 2251 tlen -= todrop; 2252 tcp_urp_drop(th, todrop, &tiflags); 2253 } 2254 2255 /* 2256 * If new data is received on a connection after the user processes 2257 * are gone, then RST the other end. 2258 */ 2259 if ((so->so_state & SS_NOFDREF) && 2260 tp->t_state > TCPS_CLOSE_WAIT && tlen) { 2261 tp = tcp_close(tp); 2262 TCP_STATINC(TCP_STAT_RCVAFTERCLOSE); 2263 goto dropwithreset; 2264 } 2265 2266 /* 2267 * If the segment ends after the window, drop trailing data (and 2268 * PUSH and FIN); if nothing left, just ACK. 2269 */ 2270 todrop = (th->th_seq + tlen) - (tp->rcv_nxt + tp->rcv_wnd); 2271 if (todrop > 0) { 2272 TCP_STATINC(TCP_STAT_RCVPACKAFTERWIN); 2273 if (todrop >= tlen) { 2274 /* 2275 * The segment actually starts after the window. 2276 * th->th_seq + tlen - tp->rcv_nxt - tp->rcv_wnd >= tlen 2277 * th->th_seq - tp->rcv_nxt - tp->rcv_wnd >= 0 2278 * th->th_seq >= tp->rcv_nxt + tp->rcv_wnd 2279 */ 2280 TCP_STATADD(TCP_STAT_RCVBYTEAFTERWIN, tlen); 2281 2282 /* 2283 * If a new connection request is received while in 2284 * TIME_WAIT, drop the old connection and start over 2285 * if the sequence numbers are above the previous 2286 * ones. 2287 * 2288 * NOTE: We need to put the header fields back into 2289 * network order. 2290 */ 2291 if ((tiflags & TH_SYN) && 2292 tp->t_state == TCPS_TIME_WAIT && 2293 SEQ_GT(th->th_seq, tp->rcv_nxt)) { 2294 tp = tcp_close(tp); 2295 tcp_fields_to_net(th); 2296 m_freem(tcp_saveti); 2297 tcp_saveti = NULL; 2298 goto findpcb; 2299 } 2300 2301 /* 2302 * If window is closed can only take segments at 2303 * window edge, and have to drop data and PUSH from 2304 * incoming segments. Continue processing, but 2305 * remember to ack. Otherwise, drop segment 2306 * and (if not RST) ack. 2307 */ 2308 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 2309 KASSERT(todrop == tlen); 2310 tp->t_flags |= TF_ACKNOW; 2311 TCP_STATINC(TCP_STAT_RCVWINPROBE); 2312 } else { 2313 goto dropafterack; 2314 } 2315 } else { 2316 TCP_STATADD(TCP_STAT_RCVBYTEAFTERWIN, todrop); 2317 } 2318 m_adj(m, -todrop); 2319 tlen -= todrop; 2320 tiflags &= ~(TH_PUSH|TH_FIN); 2321 } 2322 2323 /* 2324 * If last ACK falls within this segment's sequence numbers, 2325 * record the timestamp. 2326 * NOTE: 2327 * 1) That the test incorporates suggestions from the latest 2328 * proposal of the tcplw (at) cray.com list (Braden 1993/04/26). 2329 * 2) That updating only on newer timestamps interferes with 2330 * our earlier PAWS tests, so this check should be solely 2331 * predicated on the sequence space of this segment. 2332 * 3) That we modify the segment boundary check to be 2333 * Last.ACK.Sent <= SEG.SEQ + SEG.Len 2334 * instead of RFC1323's 2335 * Last.ACK.Sent < SEG.SEQ + SEG.Len, 2336 * This modified check allows us to overcome RFC1323's 2337 * limitations as described in Stevens TCP/IP Illustrated 2338 * Vol. 2 p.869. In such cases, we can still calculate the 2339 * RTT correctly when RCV.NXT == Last.ACK.Sent. 2340 */ 2341 if (opti.ts_present && 2342 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 2343 SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen + 2344 ((tiflags & (TH_SYN|TH_FIN)) != 0))) { 2345 tp->ts_recent_age = tcp_now; 2346 tp->ts_recent = opti.ts_val; 2347 } 2348 2349 /* 2350 * If the RST bit is set examine the state: 2351 * RECEIVED state: 2352 * If passive open, return to LISTEN state. 2353 * If active open, inform user that connection was refused. 2354 * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT states: 2355 * Inform user that connection was reset, and close tcb. 2356 * CLOSING, LAST_ACK, TIME_WAIT states: 2357 * Close the tcb. 2358 */ 2359 if (tiflags & TH_RST) { 2360 if (th->th_seq != tp->rcv_nxt) 2361 goto dropafterack_ratelim; 2362 2363 switch (tp->t_state) { 2364 case TCPS_SYN_RECEIVED: 2365 so->so_error = ECONNREFUSED; 2366 goto close; 2367 2368 case TCPS_ESTABLISHED: 2369 case TCPS_FIN_WAIT_1: 2370 case TCPS_FIN_WAIT_2: 2371 case TCPS_CLOSE_WAIT: 2372 so->so_error = ECONNRESET; 2373 close: 2374 tp->t_state = TCPS_CLOSED; 2375 TCP_STATINC(TCP_STAT_DROPS); 2376 tp = tcp_close(tp); 2377 goto drop; 2378 2379 case TCPS_CLOSING: 2380 case TCPS_LAST_ACK: 2381 case TCPS_TIME_WAIT: 2382 tp = tcp_close(tp); 2383 goto drop; 2384 } 2385 } 2386 2387 /* 2388 * Since we've covered the SYN-SENT and SYN-RECEIVED states above 2389 * we must be in a synchronized state. RFC793 states (under Reset 2390 * Generation) that any unacceptable segment (an out-of-order SYN 2391 * qualifies) received in a synchronized state must elicit only an 2392 * empty acknowledgment segment ... and the connection remains in 2393 * the same state. 2394 */ 2395 if (tiflags & TH_SYN) { 2396 if (tp->rcv_nxt == th->th_seq) { 2397 tcp_respond(tp, m, m, th, (tcp_seq)0, th->th_ack - 1, 2398 TH_ACK); 2399 if (tcp_saveti) 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 tcps[TCP_STAT_RCVACKPACK]++; 2525 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 tcps[TCP_STAT_RCVPACK]++; 2763 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 if (tcp_saveti) 2854 m_freem(tcp_saveti); 2855 2856 if (tp->t_state == TCPS_TIME_WAIT 2857 && (so->so_state & SS_NOFDREF) 2858 && (tp->t_inpcb || af != AF_INET || af != AF_INET6) 2859 && ((af == AF_INET ? tcp4_vtw_enable : tcp6_vtw_enable) & 1) != 0 2860 && TAILQ_EMPTY(&tp->segq) 2861 && vtw_add(af, tp)) { 2862 ; 2863 } 2864 return; 2865 2866 badsyn: 2867 /* 2868 * Received a bad SYN. Increment counters and dropwithreset. 2869 */ 2870 TCP_STATINC(TCP_STAT_BADSYN); 2871 tp = NULL; 2872 goto dropwithreset; 2873 2874 dropafterack: 2875 /* 2876 * Generate an ACK dropping incoming segment if it occupies 2877 * sequence space, where the ACK reflects our state. 2878 */ 2879 if (tiflags & TH_RST) 2880 goto drop; 2881 goto dropafterack2; 2882 2883 dropafterack_ratelim: 2884 /* 2885 * We may want to rate-limit ACKs against SYN/RST attack. 2886 */ 2887 if (ppsratecheck(&tcp_ackdrop_ppslim_last, &tcp_ackdrop_ppslim_count, 2888 tcp_ackdrop_ppslim) == 0) { 2889 /* XXX stat */ 2890 goto drop; 2891 } 2892 2893 dropafterack2: 2894 m_freem(m); 2895 tp->t_flags |= TF_ACKNOW; 2896 KERNEL_LOCK(1, NULL); 2897 (void)tcp_output(tp); 2898 KERNEL_UNLOCK_ONE(NULL); 2899 if (tcp_saveti) 2900 m_freem(tcp_saveti); 2901 return; 2902 2903 dropwithreset_ratelim: 2904 /* 2905 * We may want to rate-limit RSTs in certain situations, 2906 * particularly if we are sending an RST in response to 2907 * an attempt to connect to or otherwise communicate with 2908 * a port for which we have no socket. 2909 */ 2910 if (ppsratecheck(&tcp_rst_ppslim_last, &tcp_rst_ppslim_count, 2911 tcp_rst_ppslim) == 0) { 2912 /* XXX stat */ 2913 goto drop; 2914 } 2915 2916 dropwithreset: 2917 /* 2918 * Generate a RST, dropping incoming segment. 2919 * Make ACK acceptable to originator of segment. 2920 */ 2921 if (tiflags & TH_RST) 2922 goto drop; 2923 if (tiflags & TH_ACK) { 2924 (void)tcp_respond(tp, m, m, th, (tcp_seq)0, th->th_ack, TH_RST); 2925 } else { 2926 if (tiflags & TH_SYN) 2927 tlen++; 2928 (void)tcp_respond(tp, m, m, th, th->th_seq + tlen, (tcp_seq)0, 2929 TH_RST|TH_ACK); 2930 } 2931 if (tcp_saveti) 2932 m_freem(tcp_saveti); 2933 return; 2934 2935 badcsum: 2936 drop: 2937 /* 2938 * Drop space held by incoming segment and return. 2939 */ 2940 if (tp) { 2941 so = tp->t_inpcb->inp_socket; 2942 #ifdef TCP_DEBUG 2943 if (so && (so->so_options & SO_DEBUG) != 0) 2944 tcp_trace(TA_DROP, ostate, tp, tcp_saveti, 0); 2945 #endif 2946 } 2947 if (tcp_saveti) 2948 m_freem(tcp_saveti); 2949 m_freem(m); 2950 return; 2951 } 2952 2953 #ifdef TCP_SIGNATURE 2954 int 2955 tcp_signature_apply(void *fstate, void *data, u_int len) 2956 { 2957 2958 MD5Update(fstate, (u_char *)data, len); 2959 return (0); 2960 } 2961 2962 struct secasvar * 2963 tcp_signature_getsav(struct mbuf *m) 2964 { 2965 struct ip *ip; 2966 struct ip6_hdr *ip6; 2967 2968 ip = mtod(m, struct ip *); 2969 switch (ip->ip_v) { 2970 case 4: 2971 ip = mtod(m, struct ip *); 2972 ip6 = NULL; 2973 break; 2974 case 6: 2975 ip = NULL; 2976 ip6 = mtod(m, struct ip6_hdr *); 2977 break; 2978 default: 2979 return (NULL); 2980 } 2981 2982 #ifdef IPSEC 2983 union sockaddr_union dst; 2984 2985 /* Extract the destination from the IP header in the mbuf. */ 2986 memset(&dst, 0, sizeof(union sockaddr_union)); 2987 if (ip != NULL) { 2988 dst.sa.sa_len = sizeof(struct sockaddr_in); 2989 dst.sa.sa_family = AF_INET; 2990 dst.sin.sin_addr = ip->ip_dst; 2991 } else { 2992 dst.sa.sa_len = sizeof(struct sockaddr_in6); 2993 dst.sa.sa_family = AF_INET6; 2994 dst.sin6.sin6_addr = ip6->ip6_dst; 2995 } 2996 2997 /* 2998 * Look up an SADB entry which matches the address of the peer. 2999 */ 3000 return KEY_LOOKUP_SA(&dst, IPPROTO_TCP, htonl(TCP_SIG_SPI), 0, 0); 3001 #else 3002 return NULL; 3003 #endif 3004 } 3005 3006 int 3007 tcp_signature(struct mbuf *m, struct tcphdr *th, int thoff, 3008 struct secasvar *sav, char *sig) 3009 { 3010 MD5_CTX ctx; 3011 struct ip *ip; 3012 struct ipovly *ipovly; 3013 #ifdef INET6 3014 struct ip6_hdr *ip6; 3015 struct ip6_hdr_pseudo ip6pseudo; 3016 #endif 3017 struct ippseudo ippseudo; 3018 struct tcphdr th0; 3019 int l, tcphdrlen; 3020 3021 if (sav == NULL) 3022 return (-1); 3023 3024 tcphdrlen = th->th_off * 4; 3025 3026 switch (mtod(m, struct ip *)->ip_v) { 3027 case 4: 3028 MD5Init(&ctx); 3029 ip = mtod(m, struct ip *); 3030 memset(&ippseudo, 0, sizeof(ippseudo)); 3031 ipovly = (struct ipovly *)ip; 3032 ippseudo.ippseudo_src = ipovly->ih_src; 3033 ippseudo.ippseudo_dst = ipovly->ih_dst; 3034 ippseudo.ippseudo_pad = 0; 3035 ippseudo.ippseudo_p = IPPROTO_TCP; 3036 ippseudo.ippseudo_len = htons(m->m_pkthdr.len - thoff); 3037 MD5Update(&ctx, (char *)&ippseudo, sizeof(ippseudo)); 3038 break; 3039 #if INET6 3040 case 6: 3041 MD5Init(&ctx); 3042 ip6 = mtod(m, struct ip6_hdr *); 3043 memset(&ip6pseudo, 0, sizeof(ip6pseudo)); 3044 ip6pseudo.ip6ph_src = ip6->ip6_src; 3045 in6_clearscope(&ip6pseudo.ip6ph_src); 3046 ip6pseudo.ip6ph_dst = ip6->ip6_dst; 3047 in6_clearscope(&ip6pseudo.ip6ph_dst); 3048 ip6pseudo.ip6ph_len = htons(m->m_pkthdr.len - thoff); 3049 ip6pseudo.ip6ph_nxt = IPPROTO_TCP; 3050 MD5Update(&ctx, (char *)&ip6pseudo, sizeof(ip6pseudo)); 3051 break; 3052 #endif 3053 default: 3054 return (-1); 3055 } 3056 3057 th0 = *th; 3058 th0.th_sum = 0; 3059 MD5Update(&ctx, (char *)&th0, sizeof(th0)); 3060 3061 l = m->m_pkthdr.len - thoff - tcphdrlen; 3062 if (l > 0) 3063 m_apply(m, thoff + tcphdrlen, 3064 m->m_pkthdr.len - thoff - tcphdrlen, 3065 tcp_signature_apply, &ctx); 3066 3067 MD5Update(&ctx, _KEYBUF(sav->key_auth), _KEYLEN(sav->key_auth)); 3068 MD5Final(sig, &ctx); 3069 3070 return (0); 3071 } 3072 #endif 3073 3074 /* 3075 * Parse and process tcp options. 3076 * 3077 * Returns -1 if this segment should be dropped. (eg. wrong signature) 3078 * Otherwise returns 0. 3079 */ 3080 int 3081 tcp_dooptions(struct tcpcb *tp, const u_char *cp, int cnt, struct tcphdr *th, 3082 struct mbuf *m, int toff, struct tcp_opt_info *oi) 3083 { 3084 u_int16_t mss; 3085 int opt, optlen = 0; 3086 #ifdef TCP_SIGNATURE 3087 void *sigp = NULL; 3088 char sigbuf[TCP_SIGLEN]; 3089 struct secasvar *sav = NULL; 3090 #endif 3091 3092 for (; cp && cnt > 0; cnt -= optlen, cp += optlen) { 3093 opt = cp[0]; 3094 if (opt == TCPOPT_EOL) 3095 break; 3096 if (opt == TCPOPT_NOP) 3097 optlen = 1; 3098 else { 3099 if (cnt < 2) 3100 break; 3101 optlen = cp[1]; 3102 if (optlen < 2 || optlen > cnt) 3103 break; 3104 } 3105 switch (opt) { 3106 3107 default: 3108 continue; 3109 3110 case TCPOPT_MAXSEG: 3111 if (optlen != TCPOLEN_MAXSEG) 3112 continue; 3113 if (!(th->th_flags & TH_SYN)) 3114 continue; 3115 if (TCPS_HAVERCVDSYN(tp->t_state)) 3116 continue; 3117 memcpy(&mss, cp + 2, sizeof(mss)); 3118 oi->maxseg = ntohs(mss); 3119 break; 3120 3121 case TCPOPT_WINDOW: 3122 if (optlen != TCPOLEN_WINDOW) 3123 continue; 3124 if (!(th->th_flags & TH_SYN)) 3125 continue; 3126 if (TCPS_HAVERCVDSYN(tp->t_state)) 3127 continue; 3128 tp->t_flags |= TF_RCVD_SCALE; 3129 tp->requested_s_scale = cp[2]; 3130 if (tp->requested_s_scale > TCP_MAX_WINSHIFT) { 3131 char buf[INET6_ADDRSTRLEN]; 3132 struct ip *ip = mtod(m, struct ip *); 3133 #ifdef INET6 3134 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *); 3135 #endif 3136 3137 switch (ip->ip_v) { 3138 case 4: 3139 in_print(buf, sizeof(buf), 3140 &ip->ip_src); 3141 break; 3142 #ifdef INET6 3143 case 6: 3144 in6_print(buf, sizeof(buf), 3145 &ip6->ip6_src); 3146 break; 3147 #endif 3148 default: 3149 strlcpy(buf, "(unknown)", sizeof(buf)); 3150 break; 3151 } 3152 3153 log(LOG_ERR, "TCP: invalid wscale %d from %s, " 3154 "assuming %d\n", 3155 tp->requested_s_scale, buf, 3156 TCP_MAX_WINSHIFT); 3157 tp->requested_s_scale = TCP_MAX_WINSHIFT; 3158 } 3159 break; 3160 3161 case TCPOPT_TIMESTAMP: 3162 if (optlen != TCPOLEN_TIMESTAMP) 3163 continue; 3164 oi->ts_present = 1; 3165 memcpy(&oi->ts_val, cp + 2, sizeof(oi->ts_val)); 3166 NTOHL(oi->ts_val); 3167 memcpy(&oi->ts_ecr, cp + 6, sizeof(oi->ts_ecr)); 3168 NTOHL(oi->ts_ecr); 3169 3170 if (!(th->th_flags & TH_SYN)) 3171 continue; 3172 if (TCPS_HAVERCVDSYN(tp->t_state)) 3173 continue; 3174 /* 3175 * A timestamp received in a SYN makes 3176 * it ok to send timestamp requests and replies. 3177 */ 3178 tp->t_flags |= TF_RCVD_TSTMP; 3179 tp->ts_recent = oi->ts_val; 3180 tp->ts_recent_age = tcp_now; 3181 break; 3182 3183 case TCPOPT_SACK_PERMITTED: 3184 if (optlen != TCPOLEN_SACK_PERMITTED) 3185 continue; 3186 if (!(th->th_flags & TH_SYN)) 3187 continue; 3188 if (TCPS_HAVERCVDSYN(tp->t_state)) 3189 continue; 3190 if (tcp_do_sack) { 3191 tp->t_flags |= TF_SACK_PERMIT; 3192 tp->t_flags |= TF_WILL_SACK; 3193 } 3194 break; 3195 3196 case TCPOPT_SACK: 3197 tcp_sack_option(tp, th, cp, optlen); 3198 break; 3199 #ifdef TCP_SIGNATURE 3200 case TCPOPT_SIGNATURE: 3201 if (optlen != TCPOLEN_SIGNATURE) 3202 continue; 3203 if (sigp && 3204 !consttime_memequal(sigp, cp + 2, TCP_SIGLEN)) 3205 return (-1); 3206 3207 sigp = sigbuf; 3208 memcpy(sigbuf, cp + 2, TCP_SIGLEN); 3209 tp->t_flags |= TF_SIGNATURE; 3210 break; 3211 #endif 3212 } 3213 } 3214 3215 #ifndef TCP_SIGNATURE 3216 return 0; 3217 #else 3218 if (tp->t_flags & TF_SIGNATURE) { 3219 sav = tcp_signature_getsav(m); 3220 if (sav == NULL && tp->t_state == TCPS_LISTEN) 3221 return (-1); 3222 } 3223 3224 if ((sigp ? TF_SIGNATURE : 0) ^ (tp->t_flags & TF_SIGNATURE)) 3225 goto out; 3226 3227 if (sigp) { 3228 char sig[TCP_SIGLEN]; 3229 3230 tcp_fields_to_net(th); 3231 if (tcp_signature(m, th, toff, sav, sig) < 0) { 3232 tcp_fields_to_host(th); 3233 goto out; 3234 } 3235 tcp_fields_to_host(th); 3236 3237 if (!consttime_memequal(sig, sigp, TCP_SIGLEN)) { 3238 TCP_STATINC(TCP_STAT_BADSIG); 3239 goto out; 3240 } else 3241 TCP_STATINC(TCP_STAT_GOODSIG); 3242 3243 key_sa_recordxfer(sav, m); 3244 KEY_SA_UNREF(&sav); 3245 } 3246 return 0; 3247 out: 3248 if (sav != NULL) 3249 KEY_SA_UNREF(&sav); 3250 return -1; 3251 #endif 3252 } 3253 3254 /* 3255 * Pull out of band byte out of a segment so 3256 * it doesn't appear in the user's data queue. 3257 * It is still reflected in the segment length for 3258 * sequencing purposes. 3259 */ 3260 void 3261 tcp_pulloutofband(struct socket *so, struct tcphdr *th, 3262 struct mbuf *m, int off) 3263 { 3264 int cnt = off + th->th_urp - 1; 3265 3266 while (cnt >= 0) { 3267 if (m->m_len > cnt) { 3268 char *cp = mtod(m, char *) + cnt; 3269 struct tcpcb *tp = sototcpcb(so); 3270 3271 tp->t_iobc = *cp; 3272 tp->t_oobflags |= TCPOOB_HAVEDATA; 3273 memmove(cp, cp + 1, (unsigned)(m->m_len - cnt - 1)); 3274 m->m_len--; 3275 return; 3276 } 3277 cnt -= m->m_len; 3278 m = m->m_next; 3279 if (m == NULL) 3280 break; 3281 } 3282 panic("tcp_pulloutofband"); 3283 } 3284 3285 /* 3286 * Collect new round-trip time estimate 3287 * and update averages and current timeout. 3288 * 3289 * rtt is in units of slow ticks (typically 500 ms) -- essentially the 3290 * difference of two timestamps. 3291 */ 3292 void 3293 tcp_xmit_timer(struct tcpcb *tp, uint32_t rtt) 3294 { 3295 int32_t delta; 3296 3297 TCP_STATINC(TCP_STAT_RTTUPDATED); 3298 if (tp->t_srtt != 0) { 3299 /* 3300 * Compute the amount to add to srtt for smoothing, 3301 * *alpha, or 2^(-TCP_RTT_SHIFT). Because 3302 * srtt is stored in 1/32 slow ticks, we conceptually 3303 * shift left 5 bits, subtract srtt to get the 3304 * difference, and then shift right by TCP_RTT_SHIFT 3305 * (3) to obtain 1/8 of the difference. 3306 */ 3307 delta = (rtt << 2) - (tp->t_srtt >> TCP_RTT_SHIFT); 3308 /* 3309 * This can never happen, because delta's lowest 3310 * possible value is 1/8 of t_srtt. But if it does, 3311 * set srtt to some reasonable value, here chosen 3312 * as 1/8 tick. 3313 */ 3314 if ((tp->t_srtt += delta) <= 0) 3315 tp->t_srtt = 1 << 2; 3316 /* 3317 * RFC2988 requires that rttvar be updated first. 3318 * This code is compliant because "delta" is the old 3319 * srtt minus the new observation (scaled). 3320 * 3321 * RFC2988 says: 3322 * rttvar = (1-beta) * rttvar + beta * |srtt-observed| 3323 * 3324 * delta is in units of 1/32 ticks, and has then been 3325 * divided by 8. This is equivalent to being in 1/16s 3326 * units and divided by 4. Subtract from it 1/4 of 3327 * the existing rttvar to form the (signed) amount to 3328 * adjust. 3329 */ 3330 if (delta < 0) 3331 delta = -delta; 3332 delta -= (tp->t_rttvar >> TCP_RTTVAR_SHIFT); 3333 /* 3334 * As with srtt, this should never happen. There is 3335 * no support in RFC2988 for this operation. But 1/4s 3336 * as rttvar when faced with something arguably wrong 3337 * is ok. 3338 */ 3339 if ((tp->t_rttvar += delta) <= 0) 3340 tp->t_rttvar = 1 << 2; 3341 3342 /* 3343 * If srtt exceeds .01 second, ensure we use the 'remote' MSL 3344 * Problem is: it doesn't work. Disabled by defaulting 3345 * tcp_rttlocal to 0; see corresponding code in 3346 * tcp_subr that selects local vs remote in a different way. 3347 * 3348 * The static branch prediction hint here should be removed 3349 * when the rtt estimator is fixed and the rtt_enable code 3350 * is turned back on. 3351 */ 3352 if (__predict_false(tcp_rttlocal) && tcp_msl_enable 3353 && tp->t_srtt > tcp_msl_remote_threshold 3354 && tp->t_msl < tcp_msl_remote) { 3355 tp->t_msl = MIN(tcp_msl_remote, TCP_MAXMSL); 3356 } 3357 } else { 3358 /* 3359 * This is the first measurement. Per RFC2988, 2.2, 3360 * set rtt=R and srtt=R/2. 3361 * For srtt, storage representation is 1/32 ticks, 3362 * so shift left by 5. 3363 * For rttvar, storage representation is 1/16 ticks, 3364 * So shift left by 4, but then right by 1 to halve. 3365 */ 3366 tp->t_srtt = rtt << (TCP_RTT_SHIFT + 2); 3367 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT + 2 - 1); 3368 } 3369 tp->t_rtttime = 0; 3370 tp->t_rxtshift = 0; 3371 3372 /* 3373 * the retransmit should happen at rtt + 4 * rttvar. 3374 * Because of the way we do the smoothing, srtt and rttvar 3375 * will each average +1/2 tick of bias. When we compute 3376 * the retransmit timer, we want 1/2 tick of rounding and 3377 * 1 extra tick because of +-1/2 tick uncertainty in the 3378 * firing of the timer. The bias will give us exactly the 3379 * 1.5 tick we need. But, because the bias is 3380 * statistical, we have to test that we don't drop below 3381 * the minimum feasible timer (which is 2 ticks). 3382 */ 3383 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), 3384 uimax(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX); 3385 3386 /* 3387 * We received an ack for a packet that wasn't retransmitted; 3388 * it is probably safe to discard any error indications we've 3389 * received recently. This isn't quite right, but close enough 3390 * for now (a route might have failed after we sent a segment, 3391 * and the return path might not be symmetrical). 3392 */ 3393 tp->t_softerror = 0; 3394 } 3395
Indexes created Sun Sep 21 19:09:51 GMT 2025