1 /* $NetBSD: tcp_input.c,v 1.300 2010/01/26 18:09:07 pooka 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 The NetBSD Foundation, Inc. 74 * All rights reserved. 75 * 76 * This code is derived from software contributed to The NetBSD Foundation 77 * by Jason R. Thorpe and Kevin M. Lahey of the Numerical Aerospace Simulation 78 * Facility, NASA Ames Research Center. 79 * This code is derived from software contributed to The NetBSD Foundation 80 * by Charles M. Hannum. 81 * This code is derived from software contributed to The NetBSD Foundation 82 * by Rui Paulo. 83 * 84 * Redistribution and use in source and binary forms, with or without 85 * modification, are permitted provided that the following conditions 86 * are met: 87 * 1. Redistributions of source code must retain the above copyright 88 * notice, this list of conditions and the following disclaimer. 89 * 2. Redistributions in binary form must reproduce the above copyright 90 * notice, this list of conditions and the following disclaimer in the 91 * documentation and/or other materials provided with the distribution. 92 * 93 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 94 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 95 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 96 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 97 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 98 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 99 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 100 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 101 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 102 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 103 * POSSIBILITY OF SUCH DAMAGE. 104 */ 105 106 /* 107 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995 108 * The Regents of the University of California. All rights reserved. 109 * 110 * Redistribution and use in source and binary forms, with or without 111 * modification, are permitted provided that the following conditions 112 * are met: 113 * 1. Redistributions of source code must retain the above copyright 114 * notice, this list of conditions and the following disclaimer. 115 * 2. Redistributions in binary form must reproduce the above copyright 116 * notice, this list of conditions and the following disclaimer in the 117 * documentation and/or other materials provided with the distribution. 118 * 3. Neither the name of the University nor the names of its contributors 119 * may be used to endorse or promote products derived from this software 120 * without specific prior written permission. 121 * 122 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 123 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 124 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 125 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 126 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 127 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 128 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 129 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 130 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 131 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 132 * SUCH DAMAGE. 133 * 134 * @(#)tcp_input.c 8.12 (Berkeley) 5/24/95 135 */ 136 137 /* 138 * TODO list for SYN cache stuff: 139 * 140 * Find room for a "state" field, which is needed to keep a 141 * compressed state for TIME_WAIT TCBs. It's been noted already 142 * that this is fairly important for very high-volume web and 143 * mail servers, which use a large number of short-lived 144 * connections. 145 */ 146 147 #include <sys/cdefs.h> 148 __KERNEL_RCSID(0, "$NetBSD: tcp_input.c,v 1.300 2010/01/26 18:09:07 pooka Exp $"); 149 150 #include "opt_inet.h" 151 #include "opt_ipsec.h" 152 #include "opt_inet_csum.h" 153 #include "opt_tcp_debug.h" 154 155 #include <sys/param.h> 156 #include <sys/systm.h> 157 #include <sys/malloc.h> 158 #include <sys/mbuf.h> 159 #include <sys/protosw.h> 160 #include <sys/socket.h> 161 #include <sys/socketvar.h> 162 #include <sys/errno.h> 163 #include <sys/syslog.h> 164 #include <sys/pool.h> 165 #include <sys/domain.h> 166 #include <sys/kernel.h> 167 #ifdef TCP_SIGNATURE 168 #include <sys/md5.h> 169 #endif 170 #include <sys/lwp.h> /* for lwp0 */ 171 172 #include <net/if.h> 173 #include <net/route.h> 174 #include <net/if_types.h> 175 176 #include <netinet/in.h> 177 #include <netinet/in_systm.h> 178 #include <netinet/ip.h> 179 #include <netinet/in_pcb.h> 180 #include <netinet/in_var.h> 181 #include <netinet/ip_var.h> 182 #include <netinet/in_offload.h> 183 184 #ifdef INET6 185 #ifndef INET 186 #include <netinet/in.h> 187 #endif 188 #include <netinet/ip6.h> 189 #include <netinet6/ip6_var.h> 190 #include <netinet6/in6_pcb.h> 191 #include <netinet6/ip6_var.h> 192 #include <netinet6/in6_var.h> 193 #include <netinet/icmp6.h> 194 #include <netinet6/nd6.h> 195 #ifdef TCP_SIGNATURE 196 #include <netinet6/scope6_var.h> 197 #endif 198 #endif 199 200 #ifndef INET6 201 /* always need ip6.h for IP6_EXTHDR_GET */ 202 #include <netinet/ip6.h> 203 #endif 204 205 #include <netinet/tcp.h> 206 #include <netinet/tcp_fsm.h> 207 #include <netinet/tcp_seq.h> 208 #include <netinet/tcp_timer.h> 209 #include <netinet/tcp_var.h> 210 #include <netinet/tcp_private.h> 211 #include <netinet/tcpip.h> 212 #include <netinet/tcp_congctl.h> 213 #include <netinet/tcp_debug.h> 214 215 #include <machine/stdarg.h> 216 217 #ifdef IPSEC 218 #include <netinet6/ipsec.h> 219 #include <netinet6/ipsec_private.h> 220 #include <netkey/key.h> 221 #endif /*IPSEC*/ 222 #ifdef INET6 223 #include "faith.h" 224 #if defined(NFAITH) && NFAITH > 0 225 #include <net/if_faith.h> 226 #endif 227 #endif /* IPSEC */ 228 229 #ifdef FAST_IPSEC 230 #include <netipsec/ipsec.h> 231 #include <netipsec/ipsec_var.h> 232 #include <netipsec/ipsec_private.h> 233 #include <netipsec/key.h> 234 #ifdef INET6 235 #include <netipsec/ipsec6.h> 236 #endif 237 #endif /* FAST_IPSEC*/ 238 239 int tcprexmtthresh = 3; 240 int tcp_log_refused; 241 242 int tcp_do_autorcvbuf = 1; 243 int tcp_autorcvbuf_inc = 16 * 1024; 244 int tcp_autorcvbuf_max = 256 * 1024; 245 int tcp_msl = (TCPTV_MSL / PR_SLOWHZ); 246 247 static int tcp_rst_ppslim_count = 0; 248 static struct timeval tcp_rst_ppslim_last; 249 static int tcp_ackdrop_ppslim_count = 0; 250 static struct timeval tcp_ackdrop_ppslim_last; 251 252 #define TCP_PAWS_IDLE (24U * 24 * 60 * 60 * PR_SLOWHZ) 253 254 /* for modulo comparisons of timestamps */ 255 #define TSTMP_LT(a,b) ((int)((a)-(b)) < 0) 256 #define TSTMP_GEQ(a,b) ((int)((a)-(b)) >= 0) 257 258 /* 259 * Neighbor Discovery, Neighbor Unreachability Detection Upper layer hint. 260 */ 261 #ifdef INET6 262 static inline void 263 nd6_hint(struct tcpcb *tp) 264 { 265 struct rtentry *rt; 266 267 if (tp != NULL && tp->t_in6pcb != NULL && tp->t_family == AF_INET6 && 268 (rt = rtcache_validate(&tp->t_in6pcb->in6p_route)) != NULL) 269 nd6_nud_hint(rt, NULL, 0); 270 } 271 #else 272 static inline void 273 nd6_hint(struct tcpcb *tp) 274 { 275 } 276 #endif 277 278 /* 279 * Compute ACK transmission behavior. Delay the ACK unless 280 * we have already delayed an ACK (must send an ACK every two segments). 281 * We also ACK immediately if we received a PUSH and the ACK-on-PUSH 282 * option is enabled. 283 */ 284 static void 285 tcp_setup_ack(struct tcpcb *tp, const struct tcphdr *th) 286 { 287 288 if (tp->t_flags & TF_DELACK || 289 (tcp_ack_on_push && th->th_flags & TH_PUSH)) 290 tp->t_flags |= TF_ACKNOW; 291 else 292 TCP_SET_DELACK(tp); 293 } 294 295 static void 296 icmp_check(struct tcpcb *tp, const struct tcphdr *th, int acked) 297 { 298 299 /* 300 * If we had a pending ICMP message that refers to data that have 301 * just been acknowledged, disregard the recorded ICMP message. 302 */ 303 if ((tp->t_flags & TF_PMTUD_PEND) && 304 SEQ_GT(th->th_ack, tp->t_pmtud_th_seq)) 305 tp->t_flags &= ~TF_PMTUD_PEND; 306 307 /* 308 * Keep track of the largest chunk of data 309 * acknowledged since last PMTU update 310 */ 311 if (tp->t_pmtud_mss_acked < acked) 312 tp->t_pmtud_mss_acked = acked; 313 } 314 315 /* 316 * Convert TCP protocol fields to host order for easier processing. 317 */ 318 static void 319 tcp_fields_to_host(struct tcphdr *th) 320 { 321 322 NTOHL(th->th_seq); 323 NTOHL(th->th_ack); 324 NTOHS(th->th_win); 325 NTOHS(th->th_urp); 326 } 327 328 /* 329 * ... and reverse the above. 330 */ 331 static void 332 tcp_fields_to_net(struct tcphdr *th) 333 { 334 335 HTONL(th->th_seq); 336 HTONL(th->th_ack); 337 HTONS(th->th_win); 338 HTONS(th->th_urp); 339 } 340 341 #ifdef TCP_CSUM_COUNTERS 342 #include <sys/device.h> 343 344 #if defined(INET) 345 extern struct evcnt tcp_hwcsum_ok; 346 extern struct evcnt tcp_hwcsum_bad; 347 extern struct evcnt tcp_hwcsum_data; 348 extern struct evcnt tcp_swcsum; 349 #endif /* defined(INET) */ 350 #if defined(INET6) 351 extern struct evcnt tcp6_hwcsum_ok; 352 extern struct evcnt tcp6_hwcsum_bad; 353 extern struct evcnt tcp6_hwcsum_data; 354 extern struct evcnt tcp6_swcsum; 355 #endif /* defined(INET6) */ 356 357 #define TCP_CSUM_COUNTER_INCR(ev) (ev)->ev_count++ 358 359 #else 360 361 #define TCP_CSUM_COUNTER_INCR(ev) /* nothing */ 362 363 #endif /* TCP_CSUM_COUNTERS */ 364 365 #ifdef TCP_REASS_COUNTERS 366 #include <sys/device.h> 367 368 extern struct evcnt tcp_reass_; 369 extern struct evcnt tcp_reass_empty; 370 extern struct evcnt tcp_reass_iteration[8]; 371 extern struct evcnt tcp_reass_prependfirst; 372 extern struct evcnt tcp_reass_prepend; 373 extern struct evcnt tcp_reass_insert; 374 extern struct evcnt tcp_reass_inserttail; 375 extern struct evcnt tcp_reass_append; 376 extern struct evcnt tcp_reass_appendtail; 377 extern struct evcnt tcp_reass_overlaptail; 378 extern struct evcnt tcp_reass_overlapfront; 379 extern struct evcnt tcp_reass_segdup; 380 extern struct evcnt tcp_reass_fragdup; 381 382 #define TCP_REASS_COUNTER_INCR(ev) (ev)->ev_count++ 383 384 #else 385 386 #define TCP_REASS_COUNTER_INCR(ev) /* nothing */ 387 388 #endif /* TCP_REASS_COUNTERS */ 389 390 static int tcp_reass(struct tcpcb *, const struct tcphdr *, struct mbuf *, 391 int *); 392 static int tcp_dooptions(struct tcpcb *, const u_char *, int, 393 struct tcphdr *, struct mbuf *, int, struct tcp_opt_info *); 394 395 #ifdef INET 396 static void tcp4_log_refused(const struct ip *, const struct tcphdr *); 397 #endif 398 #ifdef INET6 399 static void tcp6_log_refused(const struct ip6_hdr *, const struct tcphdr *); 400 #endif 401 402 #define TRAVERSE(x) while ((x)->m_next) (x) = (x)->m_next 403 404 #if defined(MBUFTRACE) 405 struct mowner tcp_reass_mowner = MOWNER_INIT("tcp", "reass"); 406 #endif /* defined(MBUFTRACE) */ 407 408 static struct pool tcpipqent_pool; 409 410 void 411 tcpipqent_init(void) 412 { 413 414 pool_init(&tcpipqent_pool, sizeof(struct ipqent), 0, 0, 0, "tcpipqepl", 415 NULL, IPL_VM); 416 } 417 418 struct ipqent * 419 tcpipqent_alloc(void) 420 { 421 struct ipqent *ipqe; 422 int s; 423 424 s = splvm(); 425 ipqe = pool_get(&tcpipqent_pool, PR_NOWAIT); 426 splx(s); 427 428 return ipqe; 429 } 430 431 void 432 tcpipqent_free(struct ipqent *ipqe) 433 { 434 int s; 435 436 s = splvm(); 437 pool_put(&tcpipqent_pool, ipqe); 438 splx(s); 439 } 440 441 static int 442 tcp_reass(struct tcpcb *tp, const struct tcphdr *th, struct mbuf *m, int *tlen) 443 { 444 struct ipqent *p, *q, *nq, *tiqe = NULL; 445 struct socket *so = NULL; 446 int pkt_flags; 447 tcp_seq pkt_seq; 448 unsigned pkt_len; 449 u_long rcvpartdupbyte = 0; 450 u_long rcvoobyte; 451 #ifdef TCP_REASS_COUNTERS 452 u_int count = 0; 453 #endif 454 uint64_t *tcps; 455 456 if (tp->t_inpcb) 457 so = tp->t_inpcb->inp_socket; 458 #ifdef INET6 459 else if (tp->t_in6pcb) 460 so = tp->t_in6pcb->in6p_socket; 461 #endif 462 463 TCP_REASS_LOCK_CHECK(tp); 464 465 /* 466 * Call with th==0 after become established to 467 * force pre-ESTABLISHED data up to user socket. 468 */ 469 if (th == 0) 470 goto present; 471 472 m_claimm(m, &tcp_reass_mowner); 473 474 rcvoobyte = *tlen; 475 /* 476 * Copy these to local variables because the tcpiphdr 477 * gets munged while we are collapsing mbufs. 478 */ 479 pkt_seq = th->th_seq; 480 pkt_len = *tlen; 481 pkt_flags = th->th_flags; 482 483 TCP_REASS_COUNTER_INCR(&tcp_reass_); 484 485 if ((p = TAILQ_LAST(&tp->segq, ipqehead)) != NULL) { 486 /* 487 * When we miss a packet, the vast majority of time we get 488 * packets that follow it in order. So optimize for that. 489 */ 490 if (pkt_seq == p->ipqe_seq + p->ipqe_len) { 491 p->ipqe_len += pkt_len; 492 p->ipqe_flags |= pkt_flags; 493 m_cat(p->ipre_mlast, m); 494 TRAVERSE(p->ipre_mlast); 495 m = NULL; 496 tiqe = p; 497 TAILQ_REMOVE(&tp->timeq, p, ipqe_timeq); 498 TCP_REASS_COUNTER_INCR(&tcp_reass_appendtail); 499 goto skip_replacement; 500 } 501 /* 502 * While we're here, if the pkt is completely beyond 503 * anything we have, just insert it at the tail. 504 */ 505 if (SEQ_GT(pkt_seq, p->ipqe_seq + p->ipqe_len)) { 506 TCP_REASS_COUNTER_INCR(&tcp_reass_inserttail); 507 goto insert_it; 508 } 509 } 510 511 q = TAILQ_FIRST(&tp->segq); 512 513 if (q != NULL) { 514 /* 515 * If this segment immediately precedes the first out-of-order 516 * block, simply slap the segment in front of it and (mostly) 517 * skip the complicated logic. 518 */ 519 if (pkt_seq + pkt_len == q->ipqe_seq) { 520 q->ipqe_seq = pkt_seq; 521 q->ipqe_len += pkt_len; 522 q->ipqe_flags |= pkt_flags; 523 m_cat(m, q->ipqe_m); 524 q->ipqe_m = m; 525 q->ipre_mlast = m; /* last mbuf may have changed */ 526 TRAVERSE(q->ipre_mlast); 527 tiqe = q; 528 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 529 TCP_REASS_COUNTER_INCR(&tcp_reass_prependfirst); 530 goto skip_replacement; 531 } 532 } else { 533 TCP_REASS_COUNTER_INCR(&tcp_reass_empty); 534 } 535 536 /* 537 * Find a segment which begins after this one does. 538 */ 539 for (p = NULL; q != NULL; q = nq) { 540 nq = TAILQ_NEXT(q, ipqe_q); 541 #ifdef TCP_REASS_COUNTERS 542 count++; 543 #endif 544 /* 545 * If the received segment is just right after this 546 * fragment, merge the two together and then check 547 * for further overlaps. 548 */ 549 if (q->ipqe_seq + q->ipqe_len == pkt_seq) { 550 #ifdef TCPREASS_DEBUG 551 printf("tcp_reass[%p]: concat %u:%u(%u) to %u:%u(%u)\n", 552 tp, pkt_seq, pkt_seq + pkt_len, pkt_len, 553 q->ipqe_seq, q->ipqe_seq + q->ipqe_len, q->ipqe_len); 554 #endif 555 pkt_len += q->ipqe_len; 556 pkt_flags |= q->ipqe_flags; 557 pkt_seq = q->ipqe_seq; 558 m_cat(q->ipre_mlast, m); 559 TRAVERSE(q->ipre_mlast); 560 m = q->ipqe_m; 561 TCP_REASS_COUNTER_INCR(&tcp_reass_append); 562 goto free_ipqe; 563 } 564 /* 565 * If the received segment is completely past this 566 * fragment, we need to go the next fragment. 567 */ 568 if (SEQ_LT(q->ipqe_seq + q->ipqe_len, pkt_seq)) { 569 p = q; 570 continue; 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 return (0); 598 } 599 /* 600 * Received segment completely overlaps this fragment 601 * so we drop the fragment (this keeps the temporal 602 * ordering of segments correct). 603 */ 604 if (SEQ_GEQ(q->ipqe_seq, pkt_seq) && 605 SEQ_LEQ(q->ipqe_seq + q->ipqe_len, pkt_seq + pkt_len)) { 606 rcvpartdupbyte += q->ipqe_len; 607 m_freem(q->ipqe_m); 608 TCP_REASS_COUNTER_INCR(&tcp_reass_fragdup); 609 goto free_ipqe; 610 } 611 /* 612 * RX'ed segment extends past the end of the 613 * fragment. Drop the overlapping bytes. Then 614 * merge the fragment and segment then treat as 615 * a longer received packet. 616 */ 617 if (SEQ_LT(q->ipqe_seq, pkt_seq) && 618 SEQ_GT(q->ipqe_seq + q->ipqe_len, pkt_seq)) { 619 int overlap = q->ipqe_seq + q->ipqe_len - pkt_seq; 620 #ifdef TCPREASS_DEBUG 621 printf("tcp_reass[%p]: trim starting %d bytes of %u:%u(%u)\n", 622 tp, overlap, 623 pkt_seq, pkt_seq + pkt_len, pkt_len); 624 #endif 625 m_adj(m, overlap); 626 rcvpartdupbyte += overlap; 627 m_cat(q->ipre_mlast, m); 628 TRAVERSE(q->ipre_mlast); 629 m = q->ipqe_m; 630 pkt_seq = q->ipqe_seq; 631 pkt_len += q->ipqe_len - overlap; 632 rcvoobyte -= overlap; 633 TCP_REASS_COUNTER_INCR(&tcp_reass_overlaptail); 634 goto free_ipqe; 635 } 636 /* 637 * RX'ed segment extends past the front of the 638 * fragment. Drop the overlapping bytes on the 639 * received packet. The packet will then be 640 * contatentated with this fragment a bit later. 641 */ 642 if (SEQ_GT(q->ipqe_seq, pkt_seq) && 643 SEQ_LT(q->ipqe_seq, pkt_seq + pkt_len)) { 644 int overlap = pkt_seq + pkt_len - q->ipqe_seq; 645 #ifdef TCPREASS_DEBUG 646 printf("tcp_reass[%p]: trim trailing %d bytes of %u:%u(%u)\n", 647 tp, overlap, 648 pkt_seq, pkt_seq + pkt_len, pkt_len); 649 #endif 650 m_adj(m, -overlap); 651 pkt_len -= overlap; 652 rcvpartdupbyte += overlap; 653 TCP_REASS_COUNTER_INCR(&tcp_reass_overlapfront); 654 rcvoobyte -= overlap; 655 } 656 /* 657 * If the received segment immediates precedes this 658 * fragment then tack the fragment onto this segment 659 * and reinsert the data. 660 */ 661 if (q->ipqe_seq == pkt_seq + pkt_len) { 662 #ifdef TCPREASS_DEBUG 663 printf("tcp_reass[%p]: append %u:%u(%u) to %u:%u(%u)\n", 664 tp, q->ipqe_seq, q->ipqe_seq + q->ipqe_len, q->ipqe_len, 665 pkt_seq, pkt_seq + pkt_len, pkt_len); 666 #endif 667 pkt_len += q->ipqe_len; 668 pkt_flags |= q->ipqe_flags; 669 m_cat(m, q->ipqe_m); 670 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 671 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 672 tp->t_segqlen--; 673 KASSERT(tp->t_segqlen >= 0); 674 KASSERT(tp->t_segqlen != 0 || 675 (TAILQ_EMPTY(&tp->segq) && 676 TAILQ_EMPTY(&tp->timeq))); 677 if (tiqe == NULL) { 678 tiqe = q; 679 } else { 680 tcpipqent_free(q); 681 } 682 TCP_REASS_COUNTER_INCR(&tcp_reass_prepend); 683 break; 684 } 685 /* 686 * If the fragment is before the segment, remember it. 687 * When this loop is terminated, p will contain the 688 * pointer to fragment that is right before the received 689 * segment. 690 */ 691 if (SEQ_LEQ(q->ipqe_seq, pkt_seq)) 692 p = q; 693 694 continue; 695 696 /* 697 * This is a common operation. It also will allow 698 * to save doing a malloc/free in most instances. 699 */ 700 free_ipqe: 701 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 702 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 703 tp->t_segqlen--; 704 KASSERT(tp->t_segqlen >= 0); 705 KASSERT(tp->t_segqlen != 0 || 706 (TAILQ_EMPTY(&tp->segq) && TAILQ_EMPTY(&tp->timeq))); 707 if (tiqe == NULL) { 708 tiqe = q; 709 } else { 710 tcpipqent_free(q); 711 } 712 } 713 714 #ifdef TCP_REASS_COUNTERS 715 if (count > 7) 716 TCP_REASS_COUNTER_INCR(&tcp_reass_iteration[0]); 717 else if (count > 0) 718 TCP_REASS_COUNTER_INCR(&tcp_reass_iteration[count]); 719 #endif 720 721 insert_it: 722 723 /* 724 * Allocate a new queue entry since the received segment did not 725 * collapse onto any other out-of-order block; thus we are allocating 726 * a new block. If it had collapsed, tiqe would not be NULL and 727 * we would be reusing it. 728 * XXX If we can't, just drop the packet. XXX 729 */ 730 if (tiqe == NULL) { 731 tiqe = tcpipqent_alloc(); 732 if (tiqe == NULL) { 733 TCP_STATINC(TCP_STAT_RCVMEMDROP); 734 m_freem(m); 735 return (0); 736 } 737 } 738 739 /* 740 * Update the counters. 741 */ 742 tcps = TCP_STAT_GETREF(); 743 tcps[TCP_STAT_RCVOOPACK]++; 744 tcps[TCP_STAT_RCVOOBYTE] += rcvoobyte; 745 if (rcvpartdupbyte) { 746 tcps[TCP_STAT_RCVPARTDUPPACK]++; 747 tcps[TCP_STAT_RCVPARTDUPBYTE] += rcvpartdupbyte; 748 } 749 TCP_STAT_PUTREF(); 750 751 /* 752 * Insert the new fragment queue entry into both queues. 753 */ 754 tiqe->ipqe_m = m; 755 tiqe->ipre_mlast = m; 756 tiqe->ipqe_seq = pkt_seq; 757 tiqe->ipqe_len = pkt_len; 758 tiqe->ipqe_flags = pkt_flags; 759 if (p == NULL) { 760 TAILQ_INSERT_HEAD(&tp->segq, tiqe, ipqe_q); 761 #ifdef TCPREASS_DEBUG 762 if (tiqe->ipqe_seq != tp->rcv_nxt) 763 printf("tcp_reass[%p]: insert %u:%u(%u) at front\n", 764 tp, pkt_seq, pkt_seq + pkt_len, pkt_len); 765 #endif 766 } else { 767 TAILQ_INSERT_AFTER(&tp->segq, p, tiqe, ipqe_q); 768 #ifdef TCPREASS_DEBUG 769 printf("tcp_reass[%p]: insert %u:%u(%u) after %u:%u(%u)\n", 770 tp, pkt_seq, pkt_seq + pkt_len, pkt_len, 771 p->ipqe_seq, p->ipqe_seq + p->ipqe_len, p->ipqe_len); 772 #endif 773 } 774 tp->t_segqlen++; 775 776 skip_replacement: 777 778 TAILQ_INSERT_HEAD(&tp->timeq, tiqe, ipqe_timeq); 779 780 present: 781 /* 782 * Present data to user, advancing rcv_nxt through 783 * completed sequence space. 784 */ 785 if (TCPS_HAVEESTABLISHED(tp->t_state) == 0) 786 return (0); 787 q = TAILQ_FIRST(&tp->segq); 788 if (q == NULL || q->ipqe_seq != tp->rcv_nxt) 789 return (0); 790 if (tp->t_state == TCPS_SYN_RECEIVED && q->ipqe_len) 791 return (0); 792 793 tp->rcv_nxt += q->ipqe_len; 794 pkt_flags = q->ipqe_flags & TH_FIN; 795 nd6_hint(tp); 796 797 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 798 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 799 tp->t_segqlen--; 800 KASSERT(tp->t_segqlen >= 0); 801 KASSERT(tp->t_segqlen != 0 || 802 (TAILQ_EMPTY(&tp->segq) && TAILQ_EMPTY(&tp->timeq))); 803 if (so->so_state & SS_CANTRCVMORE) 804 m_freem(q->ipqe_m); 805 else 806 sbappendstream(&so->so_rcv, q->ipqe_m); 807 tcpipqent_free(q); 808 sorwakeup(so); 809 return (pkt_flags); 810 } 811 812 #ifdef INET6 813 int 814 tcp6_input(struct mbuf **mp, int *offp, int proto) 815 { 816 struct mbuf *m = *mp; 817 818 /* 819 * draft-itojun-ipv6-tcp-to-anycast 820 * better place to put this in? 821 */ 822 if (m->m_flags & M_ANYCAST6) { 823 struct ip6_hdr *ip6; 824 if (m->m_len < sizeof(struct ip6_hdr)) { 825 if ((m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) { 826 TCP_STATINC(TCP_STAT_RCVSHORT); 827 return IPPROTO_DONE; 828 } 829 } 830 ip6 = mtod(m, struct ip6_hdr *); 831 icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR, 832 (char *)&ip6->ip6_dst - (char *)ip6); 833 return IPPROTO_DONE; 834 } 835 836 tcp_input(m, *offp, proto); 837 return IPPROTO_DONE; 838 } 839 #endif 840 841 #ifdef INET 842 static void 843 tcp4_log_refused(const struct ip *ip, const struct tcphdr *th) 844 { 845 char src[4*sizeof "123"]; 846 char dst[4*sizeof "123"]; 847 848 if (ip) { 849 strlcpy(src, inet_ntoa(ip->ip_src), sizeof(src)); 850 strlcpy(dst, inet_ntoa(ip->ip_dst), sizeof(dst)); 851 } 852 else { 853 strlcpy(src, "(unknown)", sizeof(src)); 854 strlcpy(dst, "(unknown)", sizeof(dst)); 855 } 856 log(LOG_INFO, 857 "Connection attempt to TCP %s:%d from %s:%d\n", 858 dst, ntohs(th->th_dport), 859 src, ntohs(th->th_sport)); 860 } 861 #endif 862 863 #ifdef INET6 864 static void 865 tcp6_log_refused(const struct ip6_hdr *ip6, const struct tcphdr *th) 866 { 867 char src[INET6_ADDRSTRLEN]; 868 char dst[INET6_ADDRSTRLEN]; 869 870 if (ip6) { 871 strlcpy(src, ip6_sprintf(&ip6->ip6_src), sizeof(src)); 872 strlcpy(dst, ip6_sprintf(&ip6->ip6_dst), sizeof(dst)); 873 } 874 else { 875 strlcpy(src, "(unknown v6)", sizeof(src)); 876 strlcpy(dst, "(unknown v6)", sizeof(dst)); 877 } 878 log(LOG_INFO, 879 "Connection attempt to TCP [%s]:%d from [%s]:%d\n", 880 dst, ntohs(th->th_dport), 881 src, ntohs(th->th_sport)); 882 } 883 #endif 884 885 /* 886 * Checksum extended TCP header and data. 887 */ 888 int 889 tcp_input_checksum(int af, struct mbuf *m, const struct tcphdr *th, 890 int toff, int off, int tlen) 891 { 892 893 /* 894 * XXX it's better to record and check if this mbuf is 895 * already checked. 896 */ 897 898 switch (af) { 899 #ifdef INET 900 case AF_INET: 901 switch (m->m_pkthdr.csum_flags & 902 ((m->m_pkthdr.rcvif->if_csum_flags_rx & M_CSUM_TCPv4) | 903 M_CSUM_TCP_UDP_BAD | M_CSUM_DATA)) { 904 case M_CSUM_TCPv4|M_CSUM_TCP_UDP_BAD: 905 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_bad); 906 goto badcsum; 907 908 case M_CSUM_TCPv4|M_CSUM_DATA: { 909 u_int32_t hw_csum = m->m_pkthdr.csum_data; 910 911 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_data); 912 if (m->m_pkthdr.csum_flags & M_CSUM_NO_PSEUDOHDR) { 913 const struct ip *ip = 914 mtod(m, const struct ip *); 915 916 hw_csum = in_cksum_phdr(ip->ip_src.s_addr, 917 ip->ip_dst.s_addr, 918 htons(hw_csum + tlen + off + IPPROTO_TCP)); 919 } 920 if ((hw_csum ^ 0xffff) != 0) 921 goto badcsum; 922 break; 923 } 924 925 case M_CSUM_TCPv4: 926 /* Checksum was okay. */ 927 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_ok); 928 break; 929 930 default: 931 /* 932 * Must compute it ourselves. Maybe skip checksum 933 * on loopback interfaces. 934 */ 935 if (__predict_true(!(m->m_pkthdr.rcvif->if_flags & 936 IFF_LOOPBACK) || 937 tcp_do_loopback_cksum)) { 938 TCP_CSUM_COUNTER_INCR(&tcp_swcsum); 939 if (in4_cksum(m, IPPROTO_TCP, toff, 940 tlen + off) != 0) 941 goto badcsum; 942 } 943 break; 944 } 945 break; 946 #endif /* INET4 */ 947 948 #ifdef INET6 949 case AF_INET6: 950 switch (m->m_pkthdr.csum_flags & 951 ((m->m_pkthdr.rcvif->if_csum_flags_rx & M_CSUM_TCPv6) | 952 M_CSUM_TCP_UDP_BAD | M_CSUM_DATA)) { 953 case M_CSUM_TCPv6|M_CSUM_TCP_UDP_BAD: 954 TCP_CSUM_COUNTER_INCR(&tcp6_hwcsum_bad); 955 goto badcsum; 956 957 #if 0 /* notyet */ 958 case M_CSUM_TCPv6|M_CSUM_DATA: 959 #endif 960 961 case M_CSUM_TCPv6: 962 /* Checksum was okay. */ 963 TCP_CSUM_COUNTER_INCR(&tcp6_hwcsum_ok); 964 break; 965 966 default: 967 /* 968 * Must compute it ourselves. Maybe skip checksum 969 * on loopback interfaces. 970 */ 971 if (__predict_true((m->m_flags & M_LOOP) == 0 || 972 tcp_do_loopback_cksum)) { 973 TCP_CSUM_COUNTER_INCR(&tcp6_swcsum); 974 if (in6_cksum(m, IPPROTO_TCP, toff, 975 tlen + off) != 0) 976 goto badcsum; 977 } 978 } 979 break; 980 #endif /* INET6 */ 981 } 982 983 return 0; 984 985 badcsum: 986 TCP_STATINC(TCP_STAT_RCVBADSUM); 987 return -1; 988 } 989 990 /* 991 * TCP input routine, follows pages 65-76 of RFC 793 very closely. 992 */ 993 void 994 tcp_input(struct mbuf *m, ...) 995 { 996 struct tcphdr *th; 997 struct ip *ip; 998 struct inpcb *inp; 999 #ifdef INET6 1000 struct ip6_hdr *ip6; 1001 struct in6pcb *in6p; 1002 #endif 1003 u_int8_t *optp = NULL; 1004 int optlen = 0; 1005 int len, tlen, toff, hdroptlen = 0; 1006 struct tcpcb *tp = 0; 1007 int tiflags; 1008 struct socket *so = NULL; 1009 int todrop, dupseg, acked, ourfinisacked, needoutput = 0; 1010 #ifdef TCP_DEBUG 1011 short ostate = 0; 1012 #endif 1013 u_long tiwin; 1014 struct tcp_opt_info opti; 1015 int off, iphlen; 1016 va_list ap; 1017 int af; /* af on the wire */ 1018 struct mbuf *tcp_saveti = NULL; 1019 uint32_t ts_rtt; 1020 uint8_t iptos; 1021 uint64_t *tcps; 1022 1023 MCLAIM(m, &tcp_rx_mowner); 1024 va_start(ap, m); 1025 toff = va_arg(ap, int); 1026 (void)va_arg(ap, int); /* ignore value, advance ap */ 1027 va_end(ap); 1028 1029 TCP_STATINC(TCP_STAT_RCVTOTAL); 1030 1031 memset(&opti, 0, sizeof(opti)); 1032 opti.ts_present = 0; 1033 opti.maxseg = 0; 1034 1035 /* 1036 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN. 1037 * 1038 * TCP is, by definition, unicast, so we reject all 1039 * multicast outright. 1040 * 1041 * Note, there are additional src/dst address checks in 1042 * the AF-specific code below. 1043 */ 1044 if (m->m_flags & (M_BCAST|M_MCAST)) { 1045 /* XXX stat */ 1046 goto drop; 1047 } 1048 #ifdef INET6 1049 if (m->m_flags & M_ANYCAST6) { 1050 /* XXX stat */ 1051 goto drop; 1052 } 1053 #endif 1054 1055 /* 1056 * Get IP and TCP header. 1057 * Note: IP leaves IP header in first mbuf. 1058 */ 1059 ip = mtod(m, struct ip *); 1060 #ifdef INET6 1061 ip6 = NULL; 1062 #endif 1063 switch (ip->ip_v) { 1064 #ifdef INET 1065 case 4: 1066 af = AF_INET; 1067 iphlen = sizeof(struct ip); 1068 ip = mtod(m, struct ip *); 1069 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, 1070 sizeof(struct tcphdr)); 1071 if (th == NULL) { 1072 TCP_STATINC(TCP_STAT_RCVSHORT); 1073 return; 1074 } 1075 /* We do the checksum after PCB lookup... */ 1076 len = ntohs(ip->ip_len); 1077 tlen = len - toff; 1078 iptos = ip->ip_tos; 1079 break; 1080 #endif 1081 #ifdef INET6 1082 case 6: 1083 ip = NULL; 1084 iphlen = sizeof(struct ip6_hdr); 1085 af = AF_INET6; 1086 ip6 = mtod(m, struct ip6_hdr *); 1087 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, 1088 sizeof(struct tcphdr)); 1089 if (th == NULL) { 1090 TCP_STATINC(TCP_STAT_RCVSHORT); 1091 return; 1092 } 1093 1094 /* Be proactive about malicious use of IPv4 mapped address */ 1095 if (IN6_IS_ADDR_V4MAPPED(&ip6->ip6_src) || 1096 IN6_IS_ADDR_V4MAPPED(&ip6->ip6_dst)) { 1097 /* XXX stat */ 1098 goto drop; 1099 } 1100 1101 /* 1102 * Be proactive about unspecified IPv6 address in source. 1103 * As we use all-zero to indicate unbounded/unconnected pcb, 1104 * unspecified IPv6 address can be used to confuse us. 1105 * 1106 * Note that packets with unspecified IPv6 destination is 1107 * already dropped in ip6_input. 1108 */ 1109 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 1110 /* XXX stat */ 1111 goto drop; 1112 } 1113 1114 /* 1115 * Make sure destination address is not multicast. 1116 * Source address checked in ip6_input(). 1117 */ 1118 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) { 1119 /* XXX stat */ 1120 goto drop; 1121 } 1122 1123 /* We do the checksum after PCB lookup... */ 1124 len = m->m_pkthdr.len; 1125 tlen = len - toff; 1126 iptos = (ntohl(ip6->ip6_flow) >> 20) & 0xff; 1127 break; 1128 #endif 1129 default: 1130 m_freem(m); 1131 return; 1132 } 1133 1134 KASSERT(TCP_HDR_ALIGNED_P(th)); 1135 1136 /* 1137 * Check that TCP offset makes sense, 1138 * pull out TCP options and adjust length. XXX 1139 */ 1140 off = th->th_off << 2; 1141 if (off < sizeof (struct tcphdr) || off > tlen) { 1142 TCP_STATINC(TCP_STAT_RCVBADOFF); 1143 goto drop; 1144 } 1145 tlen -= off; 1146 1147 /* 1148 * tcp_input() has been modified to use tlen to mean the TCP data 1149 * length throughout the function. Other functions can use 1150 * m->m_pkthdr.len as the basis for calculating the TCP data length. 1151 * rja 1152 */ 1153 1154 if (off > sizeof (struct tcphdr)) { 1155 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, off); 1156 if (th == NULL) { 1157 TCP_STATINC(TCP_STAT_RCVSHORT); 1158 return; 1159 } 1160 /* 1161 * NOTE: ip/ip6 will not be affected by m_pulldown() 1162 * (as they're before toff) and we don't need to update those. 1163 */ 1164 KASSERT(TCP_HDR_ALIGNED_P(th)); 1165 optlen = off - sizeof (struct tcphdr); 1166 optp = ((u_int8_t *)th) + sizeof(struct tcphdr); 1167 /* 1168 * Do quick retrieval of timestamp options ("options 1169 * prediction?"). If timestamp is the only option and it's 1170 * formatted as recommended in RFC 1323 appendix A, we 1171 * quickly get the values now and not bother calling 1172 * tcp_dooptions(), etc. 1173 */ 1174 if ((optlen == TCPOLEN_TSTAMP_APPA || 1175 (optlen > TCPOLEN_TSTAMP_APPA && 1176 optp[TCPOLEN_TSTAMP_APPA] == TCPOPT_EOL)) && 1177 *(u_int32_t *)optp == htonl(TCPOPT_TSTAMP_HDR) && 1178 (th->th_flags & TH_SYN) == 0) { 1179 opti.ts_present = 1; 1180 opti.ts_val = ntohl(*(u_int32_t *)(optp + 4)); 1181 opti.ts_ecr = ntohl(*(u_int32_t *)(optp + 8)); 1182 optp = NULL; /* we've parsed the options */ 1183 } 1184 } 1185 tiflags = th->th_flags; 1186 1187 /* 1188 * Locate pcb for segment. 1189 */ 1190 findpcb: 1191 inp = NULL; 1192 #ifdef INET6 1193 in6p = NULL; 1194 #endif 1195 switch (af) { 1196 #ifdef INET 1197 case AF_INET: 1198 inp = in_pcblookup_connect(&tcbtable, ip->ip_src, th->th_sport, 1199 ip->ip_dst, th->th_dport); 1200 if (inp == 0) { 1201 TCP_STATINC(TCP_STAT_PCBHASHMISS); 1202 inp = in_pcblookup_bind(&tcbtable, ip->ip_dst, th->th_dport); 1203 } 1204 #ifdef INET6 1205 if (inp == 0) { 1206 struct in6_addr s, d; 1207 1208 /* mapped addr case */ 1209 memset(&s, 0, sizeof(s)); 1210 s.s6_addr16[5] = htons(0xffff); 1211 bcopy(&ip->ip_src, &s.s6_addr32[3], sizeof(ip->ip_src)); 1212 memset(&d, 0, sizeof(d)); 1213 d.s6_addr16[5] = htons(0xffff); 1214 bcopy(&ip->ip_dst, &d.s6_addr32[3], sizeof(ip->ip_dst)); 1215 in6p = in6_pcblookup_connect(&tcbtable, &s, 1216 th->th_sport, &d, th->th_dport, 0); 1217 if (in6p == 0) { 1218 TCP_STATINC(TCP_STAT_PCBHASHMISS); 1219 in6p = in6_pcblookup_bind(&tcbtable, &d, 1220 th->th_dport, 0); 1221 } 1222 } 1223 #endif 1224 #ifndef INET6 1225 if (inp == 0) 1226 #else 1227 if (inp == 0 && in6p == 0) 1228 #endif 1229 { 1230 TCP_STATINC(TCP_STAT_NOPORT); 1231 if (tcp_log_refused && 1232 (tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) { 1233 tcp4_log_refused(ip, th); 1234 } 1235 tcp_fields_to_host(th); 1236 goto dropwithreset_ratelim; 1237 } 1238 #if defined(IPSEC) || defined(FAST_IPSEC) 1239 if (inp && (inp->inp_socket->so_options & SO_ACCEPTCONN) == 0 && 1240 ipsec4_in_reject(m, inp)) { 1241 IPSEC_STATINC(IPSEC_STAT_IN_POLVIO); 1242 goto drop; 1243 } 1244 #ifdef INET6 1245 else if (in6p && 1246 (in6p->in6p_socket->so_options & SO_ACCEPTCONN) == 0 && 1247 ipsec6_in_reject_so(m, in6p->in6p_socket)) { 1248 IPSEC_STATINC(IPSEC_STAT_IN_POLVIO); 1249 goto drop; 1250 } 1251 #endif 1252 #endif /*IPSEC*/ 1253 break; 1254 #endif /*INET*/ 1255 #ifdef INET6 1256 case AF_INET6: 1257 { 1258 int faith; 1259 1260 #if defined(NFAITH) && NFAITH > 0 1261 faith = faithprefix(&ip6->ip6_dst); 1262 #else 1263 faith = 0; 1264 #endif 1265 in6p = in6_pcblookup_connect(&tcbtable, &ip6->ip6_src, 1266 th->th_sport, &ip6->ip6_dst, th->th_dport, faith); 1267 if (in6p == NULL) { 1268 TCP_STATINC(TCP_STAT_PCBHASHMISS); 1269 in6p = in6_pcblookup_bind(&tcbtable, &ip6->ip6_dst, 1270 th->th_dport, faith); 1271 } 1272 if (in6p == NULL) { 1273 TCP_STATINC(TCP_STAT_NOPORT); 1274 if (tcp_log_refused && 1275 (tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) { 1276 tcp6_log_refused(ip6, th); 1277 } 1278 tcp_fields_to_host(th); 1279 goto dropwithreset_ratelim; 1280 } 1281 #if defined(IPSEC) || defined(FAST_IPSEC) 1282 if ((in6p->in6p_socket->so_options & SO_ACCEPTCONN) == 0 && 1283 ipsec6_in_reject(m, in6p)) { 1284 IPSEC6_STATINC(IPSEC_STAT_IN_POLVIO); 1285 goto drop; 1286 } 1287 #endif /*IPSEC*/ 1288 break; 1289 } 1290 #endif 1291 } 1292 1293 /* 1294 * If the state is CLOSED (i.e., TCB does not exist) then 1295 * all data in the incoming segment is discarded. 1296 * If the TCB exists but is in CLOSED state, it is embryonic, 1297 * but should either do a listen or a connect soon. 1298 */ 1299 tp = NULL; 1300 so = NULL; 1301 if (inp) { 1302 /* Check the minimum TTL for socket. */ 1303 if (ip->ip_ttl < inp->inp_ip_minttl) 1304 goto drop; 1305 1306 tp = intotcpcb(inp); 1307 so = inp->inp_socket; 1308 } 1309 #ifdef INET6 1310 else if (in6p) { 1311 tp = in6totcpcb(in6p); 1312 so = in6p->in6p_socket; 1313 } 1314 #endif 1315 if (tp == 0) { 1316 tcp_fields_to_host(th); 1317 goto dropwithreset_ratelim; 1318 } 1319 if (tp->t_state == TCPS_CLOSED) 1320 goto drop; 1321 1322 KASSERT(so->so_lock == softnet_lock); 1323 KASSERT(solocked(so)); 1324 1325 /* 1326 * Checksum extended TCP header and data. 1327 */ 1328 if (tcp_input_checksum(af, m, th, toff, off, tlen)) 1329 goto badcsum; 1330 1331 tcp_fields_to_host(th); 1332 1333 /* Unscale the window into a 32-bit value. */ 1334 if ((tiflags & TH_SYN) == 0) 1335 tiwin = th->th_win << tp->snd_scale; 1336 else 1337 tiwin = th->th_win; 1338 1339 #ifdef INET6 1340 /* save packet options if user wanted */ 1341 if (in6p && (in6p->in6p_flags & IN6P_CONTROLOPTS)) { 1342 if (in6p->in6p_options) { 1343 m_freem(in6p->in6p_options); 1344 in6p->in6p_options = 0; 1345 } 1346 KASSERT(ip6 != NULL); 1347 ip6_savecontrol(in6p, &in6p->in6p_options, ip6, m); 1348 } 1349 #endif 1350 1351 if (so->so_options & (SO_DEBUG|SO_ACCEPTCONN)) { 1352 union syn_cache_sa src; 1353 union syn_cache_sa dst; 1354 1355 memset(&src, 0, sizeof(src)); 1356 memset(&dst, 0, sizeof(dst)); 1357 switch (af) { 1358 #ifdef INET 1359 case AF_INET: 1360 src.sin.sin_len = sizeof(struct sockaddr_in); 1361 src.sin.sin_family = AF_INET; 1362 src.sin.sin_addr = ip->ip_src; 1363 src.sin.sin_port = th->th_sport; 1364 1365 dst.sin.sin_len = sizeof(struct sockaddr_in); 1366 dst.sin.sin_family = AF_INET; 1367 dst.sin.sin_addr = ip->ip_dst; 1368 dst.sin.sin_port = th->th_dport; 1369 break; 1370 #endif 1371 #ifdef INET6 1372 case AF_INET6: 1373 src.sin6.sin6_len = sizeof(struct sockaddr_in6); 1374 src.sin6.sin6_family = AF_INET6; 1375 src.sin6.sin6_addr = ip6->ip6_src; 1376 src.sin6.sin6_port = th->th_sport; 1377 1378 dst.sin6.sin6_len = sizeof(struct sockaddr_in6); 1379 dst.sin6.sin6_family = AF_INET6; 1380 dst.sin6.sin6_addr = ip6->ip6_dst; 1381 dst.sin6.sin6_port = th->th_dport; 1382 break; 1383 #endif /* INET6 */ 1384 default: 1385 goto badsyn; /*sanity*/ 1386 } 1387 1388 if (so->so_options & SO_DEBUG) { 1389 #ifdef TCP_DEBUG 1390 ostate = tp->t_state; 1391 #endif 1392 1393 tcp_saveti = NULL; 1394 if (iphlen + sizeof(struct tcphdr) > MHLEN) 1395 goto nosave; 1396 1397 if (m->m_len > iphlen && (m->m_flags & M_EXT) == 0) { 1398 tcp_saveti = m_copym(m, 0, iphlen, M_DONTWAIT); 1399 if (!tcp_saveti) 1400 goto nosave; 1401 } else { 1402 MGETHDR(tcp_saveti, M_DONTWAIT, MT_HEADER); 1403 if (!tcp_saveti) 1404 goto nosave; 1405 MCLAIM(m, &tcp_mowner); 1406 tcp_saveti->m_len = iphlen; 1407 m_copydata(m, 0, iphlen, 1408 mtod(tcp_saveti, void *)); 1409 } 1410 1411 if (M_TRAILINGSPACE(tcp_saveti) < sizeof(struct tcphdr)) { 1412 m_freem(tcp_saveti); 1413 tcp_saveti = NULL; 1414 } else { 1415 tcp_saveti->m_len += sizeof(struct tcphdr); 1416 memcpy(mtod(tcp_saveti, char *) + iphlen, th, 1417 sizeof(struct tcphdr)); 1418 } 1419 nosave:; 1420 } 1421 if (so->so_options & SO_ACCEPTCONN) { 1422 if ((tiflags & (TH_RST|TH_ACK|TH_SYN)) != TH_SYN) { 1423 if (tiflags & TH_RST) { 1424 syn_cache_reset(&src.sa, &dst.sa, th); 1425 } else if ((tiflags & (TH_ACK|TH_SYN)) == 1426 (TH_ACK|TH_SYN)) { 1427 /* 1428 * Received a SYN,ACK. This should 1429 * never happen while we are in 1430 * LISTEN. Send an RST. 1431 */ 1432 goto badsyn; 1433 } else if (tiflags & TH_ACK) { 1434 so = syn_cache_get(&src.sa, &dst.sa, 1435 th, toff, tlen, so, m); 1436 if (so == NULL) { 1437 /* 1438 * We don't have a SYN for 1439 * this ACK; send an RST. 1440 */ 1441 goto badsyn; 1442 } else if (so == 1443 (struct socket *)(-1)) { 1444 /* 1445 * We were unable to create 1446 * the connection. If the 1447 * 3-way handshake was 1448 * completed, and RST has 1449 * been sent to the peer. 1450 * Since the mbuf might be 1451 * in use for the reply, 1452 * do not free it. 1453 */ 1454 m = NULL; 1455 } else { 1456 /* 1457 * We have created a 1458 * full-blown connection. 1459 */ 1460 tp = NULL; 1461 inp = NULL; 1462 #ifdef INET6 1463 in6p = NULL; 1464 #endif 1465 switch (so->so_proto->pr_domain->dom_family) { 1466 #ifdef INET 1467 case AF_INET: 1468 inp = sotoinpcb(so); 1469 tp = intotcpcb(inp); 1470 break; 1471 #endif 1472 #ifdef INET6 1473 case AF_INET6: 1474 in6p = sotoin6pcb(so); 1475 tp = in6totcpcb(in6p); 1476 break; 1477 #endif 1478 } 1479 if (tp == NULL) 1480 goto badsyn; /*XXX*/ 1481 tiwin <<= tp->snd_scale; 1482 goto after_listen; 1483 } 1484 } else { 1485 /* 1486 * None of RST, SYN or ACK was set. 1487 * This is an invalid packet for a 1488 * TCB in LISTEN state. Send a RST. 1489 */ 1490 goto badsyn; 1491 } 1492 } else { 1493 /* 1494 * Received a SYN. 1495 * 1496 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN 1497 */ 1498 if (m->m_flags & (M_BCAST|M_MCAST)) 1499 goto drop; 1500 1501 switch (af) { 1502 #ifdef INET6 1503 case AF_INET6: 1504 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) 1505 goto drop; 1506 break; 1507 #endif /* INET6 */ 1508 case AF_INET: 1509 if (IN_MULTICAST(ip->ip_dst.s_addr) || 1510 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 1511 goto drop; 1512 break; 1513 } 1514 1515 #ifdef INET6 1516 /* 1517 * If deprecated address is forbidden, we do 1518 * not accept SYN to deprecated interface 1519 * address to prevent any new inbound 1520 * connection from getting established. 1521 * When we do not accept SYN, we send a TCP 1522 * RST, with deprecated source address (instead 1523 * of dropping it). We compromise it as it is 1524 * much better for peer to send a RST, and 1525 * RST will be the final packet for the 1526 * exchange. 1527 * 1528 * If we do not forbid deprecated addresses, we 1529 * accept the SYN packet. RFC2462 does not 1530 * suggest dropping SYN in this case. 1531 * If we decipher RFC2462 5.5.4, it says like 1532 * this: 1533 * 1. use of deprecated addr with existing 1534 * communication is okay - "SHOULD continue 1535 * to be used" 1536 * 2. use of it with new communication: 1537 * (2a) "SHOULD NOT be used if alternate 1538 * address with sufficient scope is 1539 * available" 1540 * (2b) nothing mentioned otherwise. 1541 * Here we fall into (2b) case as we have no 1542 * choice in our source address selection - we 1543 * must obey the peer. 1544 * 1545 * The wording in RFC2462 is confusing, and 1546 * there are multiple description text for 1547 * deprecated address handling - worse, they 1548 * are not exactly the same. I believe 5.5.4 1549 * is the best one, so we follow 5.5.4. 1550 */ 1551 if (af == AF_INET6 && !ip6_use_deprecated) { 1552 struct in6_ifaddr *ia6; 1553 if ((ia6 = in6ifa_ifpwithaddr(m->m_pkthdr.rcvif, 1554 &ip6->ip6_dst)) && 1555 (ia6->ia6_flags & IN6_IFF_DEPRECATED)) { 1556 tp = NULL; 1557 goto dropwithreset; 1558 } 1559 } 1560 #endif 1561 1562 #if defined(IPSEC) || defined(FAST_IPSEC) 1563 switch (af) { 1564 #ifdef INET 1565 case AF_INET: 1566 if (ipsec4_in_reject_so(m, so)) { 1567 IPSEC_STATINC(IPSEC_STAT_IN_POLVIO); 1568 tp = NULL; 1569 goto dropwithreset; 1570 } 1571 break; 1572 #endif 1573 #ifdef INET6 1574 case AF_INET6: 1575 if (ipsec6_in_reject_so(m, so)) { 1576 IPSEC6_STATINC(IPSEC_STAT_IN_POLVIO); 1577 tp = NULL; 1578 goto dropwithreset; 1579 } 1580 break; 1581 #endif /*INET6*/ 1582 } 1583 #endif /*IPSEC*/ 1584 1585 /* 1586 * LISTEN socket received a SYN 1587 * from itself? This can't possibly 1588 * be valid; drop the packet. 1589 */ 1590 if (th->th_sport == th->th_dport) { 1591 int i; 1592 1593 switch (af) { 1594 #ifdef INET 1595 case AF_INET: 1596 i = in_hosteq(ip->ip_src, ip->ip_dst); 1597 break; 1598 #endif 1599 #ifdef INET6 1600 case AF_INET6: 1601 i = IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &ip6->ip6_dst); 1602 break; 1603 #endif 1604 default: 1605 i = 1; 1606 } 1607 if (i) { 1608 TCP_STATINC(TCP_STAT_BADSYN); 1609 goto drop; 1610 } 1611 } 1612 1613 /* 1614 * SYN looks ok; create compressed TCP 1615 * state for it. 1616 */ 1617 if (so->so_qlen <= so->so_qlimit && 1618 syn_cache_add(&src.sa, &dst.sa, th, tlen, 1619 so, m, optp, optlen, &opti)) 1620 m = NULL; 1621 } 1622 goto drop; 1623 } 1624 } 1625 1626 after_listen: 1627 #ifdef DIAGNOSTIC 1628 /* 1629 * Should not happen now that all embryonic connections 1630 * are handled with compressed state. 1631 */ 1632 if (tp->t_state == TCPS_LISTEN) 1633 panic("tcp_input: TCPS_LISTEN"); 1634 #endif 1635 1636 /* 1637 * Segment received on connection. 1638 * Reset idle time and keep-alive timer. 1639 */ 1640 tp->t_rcvtime = tcp_now; 1641 if (TCPS_HAVEESTABLISHED(tp->t_state)) 1642 TCP_TIMER_ARM(tp, TCPT_KEEP, tp->t_keepidle); 1643 1644 /* 1645 * Process options. 1646 */ 1647 #ifdef TCP_SIGNATURE 1648 if (optp || (tp->t_flags & TF_SIGNATURE)) 1649 #else 1650 if (optp) 1651 #endif 1652 if (tcp_dooptions(tp, optp, optlen, th, m, toff, &opti) < 0) 1653 goto drop; 1654 1655 if (TCP_SACK_ENABLED(tp)) { 1656 tcp_del_sackholes(tp, th); 1657 } 1658 1659 if (TCP_ECN_ALLOWED(tp)) { 1660 switch (iptos & IPTOS_ECN_MASK) { 1661 case IPTOS_ECN_CE: 1662 tp->t_flags |= TF_ECN_SND_ECE; 1663 TCP_STATINC(TCP_STAT_ECN_CE); 1664 break; 1665 case IPTOS_ECN_ECT0: 1666 TCP_STATINC(TCP_STAT_ECN_ECT); 1667 break; 1668 case IPTOS_ECN_ECT1: 1669 /* XXX: ignore for now -- rpaulo */ 1670 break; 1671 } 1672 1673 if (tiflags & TH_CWR) 1674 tp->t_flags &= ~TF_ECN_SND_ECE; 1675 1676 /* 1677 * Congestion experienced. 1678 * Ignore if we are already trying to recover. 1679 */ 1680 if ((tiflags & TH_ECE) && SEQ_GEQ(tp->snd_una, tp->snd_recover)) 1681 tp->t_congctl->cong_exp(tp); 1682 } 1683 1684 if (opti.ts_present && opti.ts_ecr) { 1685 /* 1686 * Calculate the RTT from the returned time stamp and the 1687 * connection's time base. If the time stamp is later than 1688 * the current time, or is extremely old, fall back to non-1323 1689 * RTT calculation. Since ts_ecr is unsigned, we can test both 1690 * at the same time. 1691 */ 1692 ts_rtt = TCP_TIMESTAMP(tp) - opti.ts_ecr + 1; 1693 if (ts_rtt > TCP_PAWS_IDLE) 1694 ts_rtt = 0; 1695 } else { 1696 ts_rtt = 0; 1697 } 1698 1699 /* 1700 * Header prediction: check for the two common cases 1701 * of a uni-directional data xfer. If the packet has 1702 * no control flags, is in-sequence, the window didn't 1703 * change and we're not retransmitting, it's a 1704 * candidate. If the length is zero and the ack moved 1705 * forward, we're the sender side of the xfer. Just 1706 * free the data acked & wake any higher level process 1707 * that was blocked waiting for space. If the length 1708 * is non-zero and the ack didn't move, we're the 1709 * receiver side. If we're getting packets in-order 1710 * (the reassembly queue is empty), add the data to 1711 * the socket buffer and note that we need a delayed ack. 1712 */ 1713 if (tp->t_state == TCPS_ESTABLISHED && 1714 (tiflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ECE|TH_CWR|TH_ACK)) 1715 == TH_ACK && 1716 (!opti.ts_present || TSTMP_GEQ(opti.ts_val, tp->ts_recent)) && 1717 th->th_seq == tp->rcv_nxt && 1718 tiwin && tiwin == tp->snd_wnd && 1719 tp->snd_nxt == tp->snd_max) { 1720 1721 /* 1722 * If last ACK falls within this segment's sequence numbers, 1723 * record the timestamp. 1724 * NOTE that the test is modified according to the latest 1725 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 1726 * 1727 * note that we already know 1728 * TSTMP_GEQ(opti.ts_val, tp->ts_recent) 1729 */ 1730 if (opti.ts_present && 1731 SEQ_LEQ(th->th_seq, tp->last_ack_sent)) { 1732 tp->ts_recent_age = tcp_now; 1733 tp->ts_recent = opti.ts_val; 1734 } 1735 1736 if (tlen == 0) { 1737 /* Ack prediction. */ 1738 if (SEQ_GT(th->th_ack, tp->snd_una) && 1739 SEQ_LEQ(th->th_ack, tp->snd_max) && 1740 tp->snd_cwnd >= tp->snd_wnd && 1741 tp->t_partialacks < 0) { 1742 /* 1743 * this is a pure ack for outstanding data. 1744 */ 1745 if (ts_rtt) 1746 tcp_xmit_timer(tp, ts_rtt); 1747 else if (tp->t_rtttime && 1748 SEQ_GT(th->th_ack, tp->t_rtseq)) 1749 tcp_xmit_timer(tp, 1750 tcp_now - tp->t_rtttime); 1751 acked = th->th_ack - tp->snd_una; 1752 tcps = TCP_STAT_GETREF(); 1753 tcps[TCP_STAT_PREDACK]++; 1754 tcps[TCP_STAT_RCVACKPACK]++; 1755 tcps[TCP_STAT_RCVACKBYTE] += acked; 1756 TCP_STAT_PUTREF(); 1757 nd6_hint(tp); 1758 1759 if (acked > (tp->t_lastoff - tp->t_inoff)) 1760 tp->t_lastm = NULL; 1761 sbdrop(&so->so_snd, acked); 1762 tp->t_lastoff -= acked; 1763 1764 icmp_check(tp, th, acked); 1765 1766 tp->snd_una = th->th_ack; 1767 tp->snd_fack = tp->snd_una; 1768 if (SEQ_LT(tp->snd_high, tp->snd_una)) 1769 tp->snd_high = tp->snd_una; 1770 m_freem(m); 1771 1772 /* 1773 * If all outstanding data are acked, stop 1774 * retransmit timer, otherwise restart timer 1775 * using current (possibly backed-off) value. 1776 * If process is waiting for space, 1777 * wakeup/selnotify/signal. If data 1778 * are ready to send, let tcp_output 1779 * decide between more output or persist. 1780 */ 1781 if (tp->snd_una == tp->snd_max) 1782 TCP_TIMER_DISARM(tp, TCPT_REXMT); 1783 else if (TCP_TIMER_ISARMED(tp, 1784 TCPT_PERSIST) == 0) 1785 TCP_TIMER_ARM(tp, TCPT_REXMT, 1786 tp->t_rxtcur); 1787 1788 sowwakeup(so); 1789 if (so->so_snd.sb_cc) 1790 (void) tcp_output(tp); 1791 if (tcp_saveti) 1792 m_freem(tcp_saveti); 1793 return; 1794 } 1795 } else if (th->th_ack == tp->snd_una && 1796 TAILQ_FIRST(&tp->segq) == NULL && 1797 tlen <= sbspace(&so->so_rcv)) { 1798 int newsize = 0; /* automatic sockbuf scaling */ 1799 1800 /* 1801 * this is a pure, in-sequence data packet 1802 * with nothing on the reassembly queue and 1803 * we have enough buffer space to take it. 1804 */ 1805 tp->rcv_nxt += tlen; 1806 tcps = TCP_STAT_GETREF(); 1807 tcps[TCP_STAT_PREDDAT]++; 1808 tcps[TCP_STAT_RCVPACK]++; 1809 tcps[TCP_STAT_RCVBYTE] += tlen; 1810 TCP_STAT_PUTREF(); 1811 nd6_hint(tp); 1812 1813 /* 1814 * Automatic sizing enables the performance of large buffers 1815 * and most of the efficiency of small ones by only allocating 1816 * space when it is needed. 1817 * 1818 * On the receive side the socket buffer memory is only rarely 1819 * used to any significant extent. This allows us to be much 1820 * more aggressive in scaling the receive socket buffer. For 1821 * the case that the buffer space is actually used to a large 1822 * extent and we run out of kernel memory we can simply drop 1823 * the new segments; TCP on the sender will just retransmit it 1824 * later. Setting the buffer size too big may only consume too 1825 * much kernel memory if the application doesn't read() from 1826 * the socket or packet loss or reordering makes use of the 1827 * reassembly queue. 1828 * 1829 * The criteria to step up the receive buffer one notch are: 1830 * 1. the number of bytes received during the time it takes 1831 * one timestamp to be reflected back to us (the RTT); 1832 * 2. received bytes per RTT is within seven eighth of the 1833 * current socket buffer size; 1834 * 3. receive buffer size has not hit maximal automatic size; 1835 * 1836 * This algorithm does one step per RTT at most and only if 1837 * we receive a bulk stream w/o packet losses or reorderings. 1838 * Shrinking the buffer during idle times is not necessary as 1839 * it doesn't consume any memory when idle. 1840 * 1841 * TODO: Only step up if the application is actually serving 1842 * the buffer to better manage the socket buffer resources. 1843 */ 1844 if (tcp_do_autorcvbuf && 1845 opti.ts_ecr && 1846 (so->so_rcv.sb_flags & SB_AUTOSIZE)) { 1847 if (opti.ts_ecr > tp->rfbuf_ts && 1848 opti.ts_ecr - tp->rfbuf_ts < PR_SLOWHZ) { 1849 if (tp->rfbuf_cnt > 1850 (so->so_rcv.sb_hiwat / 8 * 7) && 1851 so->so_rcv.sb_hiwat < 1852 tcp_autorcvbuf_max) { 1853 newsize = 1854 min(so->so_rcv.sb_hiwat + 1855 tcp_autorcvbuf_inc, 1856 tcp_autorcvbuf_max); 1857 } 1858 /* Start over with next RTT. */ 1859 tp->rfbuf_ts = 0; 1860 tp->rfbuf_cnt = 0; 1861 } else 1862 tp->rfbuf_cnt += tlen; /* add up */ 1863 } 1864 1865 /* 1866 * Drop TCP, IP headers and TCP options then add data 1867 * to socket buffer. 1868 */ 1869 if (so->so_state & SS_CANTRCVMORE) 1870 m_freem(m); 1871 else { 1872 /* 1873 * Set new socket buffer size. 1874 * Give up when limit is reached. 1875 */ 1876 if (newsize) 1877 if (!sbreserve(&so->so_rcv, 1878 newsize, so)) 1879 so->so_rcv.sb_flags &= ~SB_AUTOSIZE; 1880 m_adj(m, toff + off); 1881 sbappendstream(&so->so_rcv, m); 1882 } 1883 sorwakeup(so); 1884 tcp_setup_ack(tp, th); 1885 if (tp->t_flags & TF_ACKNOW) 1886 (void) tcp_output(tp); 1887 if (tcp_saveti) 1888 m_freem(tcp_saveti); 1889 return; 1890 } 1891 } 1892 1893 /* 1894 * Compute mbuf offset to TCP data segment. 1895 */ 1896 hdroptlen = toff + off; 1897 1898 /* 1899 * Calculate amount of space in receive window, 1900 * and then do TCP input processing. 1901 * Receive window is amount of space in rcv queue, 1902 * but not less than advertised window. 1903 */ 1904 { int win; 1905 1906 win = sbspace(&so->so_rcv); 1907 if (win < 0) 1908 win = 0; 1909 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 1910 } 1911 1912 /* Reset receive buffer auto scaling when not in bulk receive mode. */ 1913 tp->rfbuf_ts = 0; 1914 tp->rfbuf_cnt = 0; 1915 1916 switch (tp->t_state) { 1917 /* 1918 * If the state is SYN_SENT: 1919 * if seg contains an ACK, but not for our SYN, drop the input. 1920 * if seg contains a RST, then drop the connection. 1921 * if seg does not contain SYN, then drop it. 1922 * Otherwise this is an acceptable SYN segment 1923 * initialize tp->rcv_nxt and tp->irs 1924 * if seg contains ack then advance tp->snd_una 1925 * if seg contains a ECE and ECN support is enabled, the stream 1926 * is ECN capable. 1927 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 1928 * arrange for segment to be acked (eventually) 1929 * continue processing rest of data/controls, beginning with URG 1930 */ 1931 case TCPS_SYN_SENT: 1932 if ((tiflags & TH_ACK) && 1933 (SEQ_LEQ(th->th_ack, tp->iss) || 1934 SEQ_GT(th->th_ack, tp->snd_max))) 1935 goto dropwithreset; 1936 if (tiflags & TH_RST) { 1937 if (tiflags & TH_ACK) 1938 tp = tcp_drop(tp, ECONNREFUSED); 1939 goto drop; 1940 } 1941 if ((tiflags & TH_SYN) == 0) 1942 goto drop; 1943 if (tiflags & TH_ACK) { 1944 tp->snd_una = th->th_ack; 1945 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 1946 tp->snd_nxt = tp->snd_una; 1947 if (SEQ_LT(tp->snd_high, tp->snd_una)) 1948 tp->snd_high = tp->snd_una; 1949 TCP_TIMER_DISARM(tp, TCPT_REXMT); 1950 1951 if ((tiflags & TH_ECE) && tcp_do_ecn) { 1952 tp->t_flags |= TF_ECN_PERMIT; 1953 TCP_STATINC(TCP_STAT_ECN_SHS); 1954 } 1955 1956 } 1957 tp->irs = th->th_seq; 1958 tcp_rcvseqinit(tp); 1959 tp->t_flags |= TF_ACKNOW; 1960 tcp_mss_from_peer(tp, opti.maxseg); 1961 1962 /* 1963 * Initialize the initial congestion window. If we 1964 * had to retransmit the SYN, we must initialize cwnd 1965 * to 1 segment (i.e. the Loss Window). 1966 */ 1967 if (tp->t_flags & TF_SYN_REXMT) 1968 tp->snd_cwnd = tp->t_peermss; 1969 else { 1970 int ss = tcp_init_win; 1971 #ifdef INET 1972 if (inp != NULL && in_localaddr(inp->inp_faddr)) 1973 ss = tcp_init_win_local; 1974 #endif 1975 #ifdef INET6 1976 if (in6p != NULL && in6_localaddr(&in6p->in6p_faddr)) 1977 ss = tcp_init_win_local; 1978 #endif 1979 tp->snd_cwnd = TCP_INITIAL_WINDOW(ss, tp->t_peermss); 1980 } 1981 1982 tcp_rmx_rtt(tp); 1983 if (tiflags & TH_ACK) { 1984 TCP_STATINC(TCP_STAT_CONNECTS); 1985 soisconnected(so); 1986 tcp_established(tp); 1987 /* Do window scaling on this connection? */ 1988 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 1989 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 1990 tp->snd_scale = tp->requested_s_scale; 1991 tp->rcv_scale = tp->request_r_scale; 1992 } 1993 TCP_REASS_LOCK(tp); 1994 (void) tcp_reass(tp, NULL, (struct mbuf *)0, &tlen); 1995 TCP_REASS_UNLOCK(tp); 1996 /* 1997 * if we didn't have to retransmit the SYN, 1998 * use its rtt as our initial srtt & rtt var. 1999 */ 2000 if (tp->t_rtttime) 2001 tcp_xmit_timer(tp, tcp_now - tp->t_rtttime); 2002 } else 2003 tp->t_state = TCPS_SYN_RECEIVED; 2004 2005 /* 2006 * Advance th->th_seq to correspond to first data byte. 2007 * If data, trim to stay within window, 2008 * dropping FIN if necessary. 2009 */ 2010 th->th_seq++; 2011 if (tlen > tp->rcv_wnd) { 2012 todrop = tlen - tp->rcv_wnd; 2013 m_adj(m, -todrop); 2014 tlen = tp->rcv_wnd; 2015 tiflags &= ~TH_FIN; 2016 tcps = TCP_STAT_GETREF(); 2017 tcps[TCP_STAT_RCVPACKAFTERWIN]++; 2018 tcps[TCP_STAT_RCVBYTEAFTERWIN] += todrop; 2019 TCP_STAT_PUTREF(); 2020 } 2021 tp->snd_wl1 = th->th_seq - 1; 2022 tp->rcv_up = th->th_seq; 2023 goto step6; 2024 2025 /* 2026 * If the state is SYN_RECEIVED: 2027 * If seg contains an ACK, but not for our SYN, drop the input 2028 * and generate an RST. See page 36, rfc793 2029 */ 2030 case TCPS_SYN_RECEIVED: 2031 if ((tiflags & TH_ACK) && 2032 (SEQ_LEQ(th->th_ack, tp->iss) || 2033 SEQ_GT(th->th_ack, tp->snd_max))) 2034 goto dropwithreset; 2035 break; 2036 } 2037 2038 /* 2039 * States other than LISTEN or SYN_SENT. 2040 * First check timestamp, if present. 2041 * Then check that at least some bytes of segment are within 2042 * receive window. If segment begins before rcv_nxt, 2043 * drop leading data (and SYN); if nothing left, just ack. 2044 * 2045 * RFC 1323 PAWS: If we have a timestamp reply on this segment 2046 * and it's less than ts_recent, drop it. 2047 */ 2048 if (opti.ts_present && (tiflags & TH_RST) == 0 && tp->ts_recent && 2049 TSTMP_LT(opti.ts_val, tp->ts_recent)) { 2050 2051 /* Check to see if ts_recent is over 24 days old. */ 2052 if (tcp_now - tp->ts_recent_age > TCP_PAWS_IDLE) { 2053 /* 2054 * Invalidate ts_recent. If this segment updates 2055 * ts_recent, the age will be reset later and ts_recent 2056 * will get a valid value. If it does not, setting 2057 * ts_recent to zero will at least satisfy the 2058 * requirement that zero be placed in the timestamp 2059 * echo reply when ts_recent isn't valid. The 2060 * age isn't reset until we get a valid ts_recent 2061 * because we don't want out-of-order segments to be 2062 * dropped when ts_recent is old. 2063 */ 2064 tp->ts_recent = 0; 2065 } else { 2066 tcps = TCP_STAT_GETREF(); 2067 tcps[TCP_STAT_RCVDUPPACK]++; 2068 tcps[TCP_STAT_RCVDUPBYTE] += tlen; 2069 tcps[TCP_STAT_PAWSDROP]++; 2070 TCP_STAT_PUTREF(); 2071 tcp_new_dsack(tp, th->th_seq, tlen); 2072 goto dropafterack; 2073 } 2074 } 2075 2076 todrop = tp->rcv_nxt - th->th_seq; 2077 dupseg = false; 2078 if (todrop > 0) { 2079 if (tiflags & TH_SYN) { 2080 tiflags &= ~TH_SYN; 2081 th->th_seq++; 2082 if (th->th_urp > 1) 2083 th->th_urp--; 2084 else { 2085 tiflags &= ~TH_URG; 2086 th->th_urp = 0; 2087 } 2088 todrop--; 2089 } 2090 if (todrop > tlen || 2091 (todrop == tlen && (tiflags & TH_FIN) == 0)) { 2092 /* 2093 * Any valid FIN or RST must be to the left of the 2094 * window. At this point the FIN or RST must be a 2095 * duplicate or out of sequence; drop it. 2096 */ 2097 if (tiflags & TH_RST) 2098 goto drop; 2099 tiflags &= ~(TH_FIN|TH_RST); 2100 /* 2101 * Send an ACK to resynchronize and drop any data. 2102 * But keep on processing for RST or ACK. 2103 */ 2104 tp->t_flags |= TF_ACKNOW; 2105 todrop = tlen; 2106 dupseg = true; 2107 tcps = TCP_STAT_GETREF(); 2108 tcps[TCP_STAT_RCVDUPPACK]++; 2109 tcps[TCP_STAT_RCVDUPBYTE] += todrop; 2110 TCP_STAT_PUTREF(); 2111 } else if ((tiflags & TH_RST) && 2112 th->th_seq != tp->rcv_nxt) { 2113 /* 2114 * Test for reset before adjusting the sequence 2115 * number for overlapping data. 2116 */ 2117 goto dropafterack_ratelim; 2118 } else { 2119 tcps = TCP_STAT_GETREF(); 2120 tcps[TCP_STAT_RCVPARTDUPPACK]++; 2121 tcps[TCP_STAT_RCVPARTDUPBYTE] += todrop; 2122 TCP_STAT_PUTREF(); 2123 } 2124 tcp_new_dsack(tp, th->th_seq, todrop); 2125 hdroptlen += todrop; /*drop from head afterwards*/ 2126 th->th_seq += todrop; 2127 tlen -= todrop; 2128 if (th->th_urp > todrop) 2129 th->th_urp -= todrop; 2130 else { 2131 tiflags &= ~TH_URG; 2132 th->th_urp = 0; 2133 } 2134 } 2135 2136 /* 2137 * If new data are received on a connection after the 2138 * user processes are gone, then RST the other end. 2139 */ 2140 if ((so->so_state & SS_NOFDREF) && 2141 tp->t_state > TCPS_CLOSE_WAIT && tlen) { 2142 tp = tcp_close(tp); 2143 TCP_STATINC(TCP_STAT_RCVAFTERCLOSE); 2144 goto dropwithreset; 2145 } 2146 2147 /* 2148 * If segment ends after window, drop trailing data 2149 * (and PUSH and FIN); if nothing left, just ACK. 2150 */ 2151 todrop = (th->th_seq + tlen) - (tp->rcv_nxt+tp->rcv_wnd); 2152 if (todrop > 0) { 2153 TCP_STATINC(TCP_STAT_RCVPACKAFTERWIN); 2154 if (todrop >= tlen) { 2155 /* 2156 * The segment actually starts after the window. 2157 * th->th_seq + tlen - tp->rcv_nxt - tp->rcv_wnd >= tlen 2158 * th->th_seq - tp->rcv_nxt - tp->rcv_wnd >= 0 2159 * th->th_seq >= tp->rcv_nxt + tp->rcv_wnd 2160 */ 2161 TCP_STATADD(TCP_STAT_RCVBYTEAFTERWIN, tlen); 2162 /* 2163 * If a new connection request is received 2164 * while in TIME_WAIT, drop the old connection 2165 * and start over if the sequence numbers 2166 * are above the previous ones. 2167 * 2168 * NOTE: We will checksum the packet again, and 2169 * so we need to put the header fields back into 2170 * network order! 2171 * XXX This kind of sucks, but we don't expect 2172 * XXX this to happen very often, so maybe it 2173 * XXX doesn't matter so much. 2174 */ 2175 if (tiflags & TH_SYN && 2176 tp->t_state == TCPS_TIME_WAIT && 2177 SEQ_GT(th->th_seq, tp->rcv_nxt)) { 2178 tp = tcp_close(tp); 2179 tcp_fields_to_net(th); 2180 goto findpcb; 2181 } 2182 /* 2183 * If window is closed can only take segments at 2184 * window edge, and have to drop data and PUSH from 2185 * incoming segments. Continue processing, but 2186 * remember to ack. Otherwise, drop segment 2187 * and (if not RST) ack. 2188 */ 2189 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 2190 tp->t_flags |= TF_ACKNOW; 2191 TCP_STATINC(TCP_STAT_RCVWINPROBE); 2192 } else 2193 goto dropafterack; 2194 } else 2195 TCP_STATADD(TCP_STAT_RCVBYTEAFTERWIN, todrop); 2196 m_adj(m, -todrop); 2197 tlen -= todrop; 2198 tiflags &= ~(TH_PUSH|TH_FIN); 2199 } 2200 2201 /* 2202 * If last ACK falls within this segment's sequence numbers, 2203 * record the timestamp. 2204 * NOTE: 2205 * 1) That the test incorporates suggestions from the latest 2206 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 2207 * 2) That updating only on newer timestamps interferes with 2208 * our earlier PAWS tests, so this check should be solely 2209 * predicated on the sequence space of this segment. 2210 * 3) That we modify the segment boundary check to be 2211 * Last.ACK.Sent <= SEG.SEQ + SEG.Len 2212 * instead of RFC1323's 2213 * Last.ACK.Sent < SEG.SEQ + SEG.Len, 2214 * This modified check allows us to overcome RFC1323's 2215 * limitations as described in Stevens TCP/IP Illustrated 2216 * Vol. 2 p.869. In such cases, we can still calculate the 2217 * RTT correctly when RCV.NXT == Last.ACK.Sent. 2218 */ 2219 if (opti.ts_present && 2220 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 2221 SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen + 2222 ((tiflags & (TH_SYN|TH_FIN)) != 0))) { 2223 tp->ts_recent_age = tcp_now; 2224 tp->ts_recent = opti.ts_val; 2225 } 2226 2227 /* 2228 * If the RST bit is set examine the state: 2229 * SYN_RECEIVED STATE: 2230 * If passive open, return to LISTEN state. 2231 * If active open, inform user that connection was refused. 2232 * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES: 2233 * Inform user that connection was reset, and close tcb. 2234 * CLOSING, LAST_ACK, TIME_WAIT STATES 2235 * Close the tcb. 2236 */ 2237 if (tiflags & TH_RST) { 2238 if (th->th_seq != tp->rcv_nxt) 2239 goto dropafterack_ratelim; 2240 2241 switch (tp->t_state) { 2242 case TCPS_SYN_RECEIVED: 2243 so->so_error = ECONNREFUSED; 2244 goto close; 2245 2246 case TCPS_ESTABLISHED: 2247 case TCPS_FIN_WAIT_1: 2248 case TCPS_FIN_WAIT_2: 2249 case TCPS_CLOSE_WAIT: 2250 so->so_error = ECONNRESET; 2251 close: 2252 tp->t_state = TCPS_CLOSED; 2253 TCP_STATINC(TCP_STAT_DROPS); 2254 tp = tcp_close(tp); 2255 goto drop; 2256 2257 case TCPS_CLOSING: 2258 case TCPS_LAST_ACK: 2259 case TCPS_TIME_WAIT: 2260 tp = tcp_close(tp); 2261 goto drop; 2262 } 2263 } 2264 2265 /* 2266 * Since we've covered the SYN-SENT and SYN-RECEIVED states above 2267 * we must be in a synchronized state. RFC791 states (under RST 2268 * generation) that any unacceptable segment (an out-of-order SYN 2269 * qualifies) received in a synchronized state must elicit only an 2270 * empty acknowledgment segment ... and the connection remains in 2271 * the same state. 2272 */ 2273 if (tiflags & TH_SYN) { 2274 if (tp->rcv_nxt == th->th_seq) { 2275 tcp_respond(tp, m, m, th, (tcp_seq)0, th->th_ack - 1, 2276 TH_ACK); 2277 if (tcp_saveti) 2278 m_freem(tcp_saveti); 2279 return; 2280 } 2281 2282 goto dropafterack_ratelim; 2283 } 2284 2285 /* 2286 * If the ACK bit is off we drop the segment and return. 2287 */ 2288 if ((tiflags & TH_ACK) == 0) { 2289 if (tp->t_flags & TF_ACKNOW) 2290 goto dropafterack; 2291 else 2292 goto drop; 2293 } 2294 2295 /* 2296 * Ack processing. 2297 */ 2298 switch (tp->t_state) { 2299 2300 /* 2301 * In SYN_RECEIVED state if the ack ACKs our SYN then enter 2302 * ESTABLISHED state and continue processing, otherwise 2303 * send an RST. 2304 */ 2305 case TCPS_SYN_RECEIVED: 2306 if (SEQ_GT(tp->snd_una, th->th_ack) || 2307 SEQ_GT(th->th_ack, tp->snd_max)) 2308 goto dropwithreset; 2309 TCP_STATINC(TCP_STAT_CONNECTS); 2310 soisconnected(so); 2311 tcp_established(tp); 2312 /* Do window scaling? */ 2313 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2314 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2315 tp->snd_scale = tp->requested_s_scale; 2316 tp->rcv_scale = tp->request_r_scale; 2317 } 2318 TCP_REASS_LOCK(tp); 2319 (void) tcp_reass(tp, NULL, (struct mbuf *)0, &tlen); 2320 TCP_REASS_UNLOCK(tp); 2321 tp->snd_wl1 = th->th_seq - 1; 2322 /* fall into ... */ 2323 2324 /* 2325 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 2326 * ACKs. If the ack is in the range 2327 * tp->snd_una < th->th_ack <= tp->snd_max 2328 * then advance tp->snd_una to th->th_ack and drop 2329 * data from the retransmission queue. If this ACK reflects 2330 * more up to date window information we update our window information. 2331 */ 2332 case TCPS_ESTABLISHED: 2333 case TCPS_FIN_WAIT_1: 2334 case TCPS_FIN_WAIT_2: 2335 case TCPS_CLOSE_WAIT: 2336 case TCPS_CLOSING: 2337 case TCPS_LAST_ACK: 2338 case TCPS_TIME_WAIT: 2339 2340 if (SEQ_LEQ(th->th_ack, tp->snd_una)) { 2341 if (tlen == 0 && !dupseg && tiwin == tp->snd_wnd) { 2342 TCP_STATINC(TCP_STAT_RCVDUPPACK); 2343 /* 2344 * If we have outstanding data (other than 2345 * a window probe), this is a completely 2346 * duplicate ack (ie, window info didn't 2347 * change), the ack is the biggest we've 2348 * seen and we've seen exactly our rexmt 2349 * threshhold of them, assume a packet 2350 * has been dropped and retransmit it. 2351 * Kludge snd_nxt & the congestion 2352 * window so we send only this one 2353 * packet. 2354 */ 2355 if (TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 || 2356 th->th_ack != tp->snd_una) 2357 tp->t_dupacks = 0; 2358 else if (tp->t_partialacks < 0 && 2359 (++tp->t_dupacks == tcprexmtthresh || 2360 TCP_FACK_FASTRECOV(tp))) { 2361 /* 2362 * Do the fast retransmit, and adjust 2363 * congestion control paramenters. 2364 */ 2365 if (tp->t_congctl->fast_retransmit(tp, th)) { 2366 /* False fast retransmit */ 2367 break; 2368 } else 2369 goto drop; 2370 } else if (tp->t_dupacks > tcprexmtthresh) { 2371 tp->snd_cwnd += tp->t_segsz; 2372 (void) tcp_output(tp); 2373 goto drop; 2374 } 2375 } else { 2376 /* 2377 * If the ack appears to be very old, only 2378 * allow data that is in-sequence. This 2379 * makes it somewhat more difficult to insert 2380 * forged data by guessing sequence numbers. 2381 * Sent an ack to try to update the send 2382 * sequence number on the other side. 2383 */ 2384 if (tlen && th->th_seq != tp->rcv_nxt && 2385 SEQ_LT(th->th_ack, 2386 tp->snd_una - tp->max_sndwnd)) 2387 goto dropafterack; 2388 } 2389 break; 2390 } 2391 /* 2392 * If the congestion window was inflated to account 2393 * for the other side's cached packets, retract it. 2394 */ 2395 /* XXX: make SACK have his own congestion control 2396 * struct -- rpaulo */ 2397 if (TCP_SACK_ENABLED(tp)) 2398 tcp_sack_newack(tp, th); 2399 else 2400 tp->t_congctl->fast_retransmit_newack(tp, th); 2401 if (SEQ_GT(th->th_ack, tp->snd_max)) { 2402 TCP_STATINC(TCP_STAT_RCVACKTOOMUCH); 2403 goto dropafterack; 2404 } 2405 acked = th->th_ack - tp->snd_una; 2406 tcps = TCP_STAT_GETREF(); 2407 tcps[TCP_STAT_RCVACKPACK]++; 2408 tcps[TCP_STAT_RCVACKBYTE] += acked; 2409 TCP_STAT_PUTREF(); 2410 2411 /* 2412 * If we have a timestamp reply, update smoothed 2413 * round trip time. If no timestamp is present but 2414 * transmit timer is running and timed sequence 2415 * number was acked, update smoothed round trip time. 2416 * Since we now have an rtt measurement, cancel the 2417 * timer backoff (cf., Phil Karn's retransmit alg.). 2418 * Recompute the initial retransmit timer. 2419 */ 2420 if (ts_rtt) 2421 tcp_xmit_timer(tp, ts_rtt); 2422 else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) 2423 tcp_xmit_timer(tp, tcp_now - tp->t_rtttime); 2424 2425 /* 2426 * If all outstanding data is acked, stop retransmit 2427 * timer and remember to restart (more output or persist). 2428 * If there is more data to be acked, restart retransmit 2429 * timer, using current (possibly backed-off) value. 2430 */ 2431 if (th->th_ack == tp->snd_max) { 2432 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2433 needoutput = 1; 2434 } else if (TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) 2435 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 2436 2437 /* 2438 * New data has been acked, adjust the congestion window. 2439 */ 2440 tp->t_congctl->newack(tp, th); 2441 2442 nd6_hint(tp); 2443 if (acked > so->so_snd.sb_cc) { 2444 tp->snd_wnd -= so->so_snd.sb_cc; 2445 sbdrop(&so->so_snd, (int)so->so_snd.sb_cc); 2446 ourfinisacked = 1; 2447 } else { 2448 if (acked > (tp->t_lastoff - tp->t_inoff)) 2449 tp->t_lastm = NULL; 2450 sbdrop(&so->so_snd, acked); 2451 tp->t_lastoff -= acked; 2452 tp->snd_wnd -= acked; 2453 ourfinisacked = 0; 2454 } 2455 sowwakeup(so); 2456 2457 icmp_check(tp, th, acked); 2458 2459 tp->snd_una = th->th_ack; 2460 if (SEQ_GT(tp->snd_una, tp->snd_fack)) 2461 tp->snd_fack = tp->snd_una; 2462 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2463 tp->snd_nxt = tp->snd_una; 2464 if (SEQ_LT(tp->snd_high, tp->snd_una)) 2465 tp->snd_high = tp->snd_una; 2466 2467 switch (tp->t_state) { 2468 2469 /* 2470 * In FIN_WAIT_1 STATE in addition to the processing 2471 * for the ESTABLISHED state if our FIN is now acknowledged 2472 * then enter FIN_WAIT_2. 2473 */ 2474 case TCPS_FIN_WAIT_1: 2475 if (ourfinisacked) { 2476 /* 2477 * If we can't receive any more 2478 * data, then closing user can proceed. 2479 * Starting the timer is contrary to the 2480 * specification, but if we don't get a FIN 2481 * we'll hang forever. 2482 */ 2483 if (so->so_state & SS_CANTRCVMORE) { 2484 soisdisconnected(so); 2485 if (tp->t_maxidle > 0) 2486 TCP_TIMER_ARM(tp, TCPT_2MSL, 2487 tp->t_maxidle); 2488 } 2489 tp->t_state = TCPS_FIN_WAIT_2; 2490 } 2491 break; 2492 2493 /* 2494 * In CLOSING STATE in addition to the processing for 2495 * the ESTABLISHED state if the ACK acknowledges our FIN 2496 * then enter the TIME-WAIT state, otherwise ignore 2497 * the segment. 2498 */ 2499 case TCPS_CLOSING: 2500 if (ourfinisacked) { 2501 tp->t_state = TCPS_TIME_WAIT; 2502 tcp_canceltimers(tp); 2503 TCP_TIMER_ARM(tp, TCPT_2MSL, 2504 2 * PR_SLOWHZ * tcp_msl); 2505 soisdisconnected(so); 2506 } 2507 break; 2508 2509 /* 2510 * In LAST_ACK, we may still be waiting for data to drain 2511 * and/or to be acked, as well as for the ack of our FIN. 2512 * If our FIN is now acknowledged, delete the TCB, 2513 * enter the closed state and return. 2514 */ 2515 case TCPS_LAST_ACK: 2516 if (ourfinisacked) { 2517 tp = tcp_close(tp); 2518 goto drop; 2519 } 2520 break; 2521 2522 /* 2523 * In TIME_WAIT state the only thing that should arrive 2524 * is a retransmission of the remote FIN. Acknowledge 2525 * it and restart the finack timer. 2526 */ 2527 case TCPS_TIME_WAIT: 2528 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * PR_SLOWHZ * tcp_msl); 2529 goto dropafterack; 2530 } 2531 } 2532 2533 step6: 2534 /* 2535 * Update window information. 2536 * Don't look at window if no ACK: TAC's send garbage on first SYN. 2537 */ 2538 if ((tiflags & TH_ACK) && (SEQ_LT(tp->snd_wl1, th->th_seq) || 2539 (tp->snd_wl1 == th->th_seq && (SEQ_LT(tp->snd_wl2, th->th_ack) || 2540 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))) { 2541 /* keep track of pure window updates */ 2542 if (tlen == 0 && 2543 tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) 2544 TCP_STATINC(TCP_STAT_RCVWINUPD); 2545 tp->snd_wnd = tiwin; 2546 tp->snd_wl1 = th->th_seq; 2547 tp->snd_wl2 = th->th_ack; 2548 if (tp->snd_wnd > tp->max_sndwnd) 2549 tp->max_sndwnd = tp->snd_wnd; 2550 needoutput = 1; 2551 } 2552 2553 /* 2554 * Process segments with URG. 2555 */ 2556 if ((tiflags & TH_URG) && th->th_urp && 2557 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2558 /* 2559 * This is a kludge, but if we receive and accept 2560 * random urgent pointers, we'll crash in 2561 * soreceive. It's hard to imagine someone 2562 * actually wanting to send this much urgent data. 2563 */ 2564 if (th->th_urp + so->so_rcv.sb_cc > sb_max) { 2565 th->th_urp = 0; /* XXX */ 2566 tiflags &= ~TH_URG; /* XXX */ 2567 goto dodata; /* XXX */ 2568 } 2569 /* 2570 * If this segment advances the known urgent pointer, 2571 * then mark the data stream. This should not happen 2572 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 2573 * a FIN has been received from the remote side. 2574 * In these states we ignore the URG. 2575 * 2576 * According to RFC961 (Assigned Protocols), 2577 * the urgent pointer points to the last octet 2578 * of urgent data. We continue, however, 2579 * to consider it to indicate the first octet 2580 * of data past the urgent section as the original 2581 * spec states (in one of two places). 2582 */ 2583 if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) { 2584 tp->rcv_up = th->th_seq + th->th_urp; 2585 so->so_oobmark = so->so_rcv.sb_cc + 2586 (tp->rcv_up - tp->rcv_nxt) - 1; 2587 if (so->so_oobmark == 0) 2588 so->so_state |= SS_RCVATMARK; 2589 sohasoutofband(so); 2590 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); 2591 } 2592 /* 2593 * Remove out of band data so doesn't get presented to user. 2594 * This can happen independent of advancing the URG pointer, 2595 * but if two URG's are pending at once, some out-of-band 2596 * data may creep in... ick. 2597 */ 2598 if (th->th_urp <= (u_int16_t) tlen 2599 #ifdef SO_OOBINLINE 2600 && (so->so_options & SO_OOBINLINE) == 0 2601 #endif 2602 ) 2603 tcp_pulloutofband(so, th, m, hdroptlen); 2604 } else 2605 /* 2606 * If no out of band data is expected, 2607 * pull receive urgent pointer along 2608 * with the receive window. 2609 */ 2610 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) 2611 tp->rcv_up = tp->rcv_nxt; 2612 dodata: /* XXX */ 2613 2614 /* 2615 * Process the segment text, merging it into the TCP sequencing queue, 2616 * and arranging for acknowledgement of receipt if necessary. 2617 * This process logically involves adjusting tp->rcv_wnd as data 2618 * is presented to the user (this happens in tcp_usrreq.c, 2619 * case PRU_RCVD). If a FIN has already been received on this 2620 * connection then we just ignore the text. 2621 */ 2622 if ((tlen || (tiflags & TH_FIN)) && 2623 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2624 /* 2625 * Insert segment ti into reassembly queue of tcp with 2626 * control block tp. Return TH_FIN if reassembly now includes 2627 * a segment with FIN. The macro form does the common case 2628 * inline (segment is the next to be received on an 2629 * established connection, and the queue is empty), 2630 * avoiding linkage into and removal from the queue and 2631 * repetition of various conversions. 2632 * Set DELACK for segments received in order, but ack 2633 * immediately when segments are out of order 2634 * (so fast retransmit can work). 2635 */ 2636 /* NOTE: this was TCP_REASS() macro, but used only once */ 2637 TCP_REASS_LOCK(tp); 2638 if (th->th_seq == tp->rcv_nxt && 2639 TAILQ_FIRST(&tp->segq) == NULL && 2640 tp->t_state == TCPS_ESTABLISHED) { 2641 tcp_setup_ack(tp, th); 2642 tp->rcv_nxt += tlen; 2643 tiflags = th->th_flags & TH_FIN; 2644 tcps = TCP_STAT_GETREF(); 2645 tcps[TCP_STAT_RCVPACK]++; 2646 tcps[TCP_STAT_RCVBYTE] += tlen; 2647 TCP_STAT_PUTREF(); 2648 nd6_hint(tp); 2649 if (so->so_state & SS_CANTRCVMORE) 2650 m_freem(m); 2651 else { 2652 m_adj(m, hdroptlen); 2653 sbappendstream(&(so)->so_rcv, m); 2654 } 2655 TCP_REASS_UNLOCK(tp); 2656 sorwakeup(so); 2657 } else { 2658 m_adj(m, hdroptlen); 2659 tiflags = tcp_reass(tp, th, m, &tlen); 2660 tp->t_flags |= TF_ACKNOW; 2661 TCP_REASS_UNLOCK(tp); 2662 } 2663 2664 /* 2665 * Note the amount of data that peer has sent into 2666 * our window, in order to estimate the sender's 2667 * buffer size. 2668 */ 2669 len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); 2670 } else { 2671 m_freem(m); 2672 m = NULL; 2673 tiflags &= ~TH_FIN; 2674 } 2675 2676 /* 2677 * If FIN is received ACK the FIN and let the user know 2678 * that the connection is closing. Ignore a FIN received before 2679 * the connection is fully established. 2680 */ 2681 if ((tiflags & TH_FIN) && TCPS_HAVEESTABLISHED(tp->t_state)) { 2682 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2683 socantrcvmore(so); 2684 tp->t_flags |= TF_ACKNOW; 2685 tp->rcv_nxt++; 2686 } 2687 switch (tp->t_state) { 2688 2689 /* 2690 * In ESTABLISHED STATE enter the CLOSE_WAIT state. 2691 */ 2692 case TCPS_ESTABLISHED: 2693 tp->t_state = TCPS_CLOSE_WAIT; 2694 break; 2695 2696 /* 2697 * If still in FIN_WAIT_1 STATE FIN has not been acked so 2698 * enter the CLOSING state. 2699 */ 2700 case TCPS_FIN_WAIT_1: 2701 tp->t_state = TCPS_CLOSING; 2702 break; 2703 2704 /* 2705 * In FIN_WAIT_2 state enter the TIME_WAIT state, 2706 * starting the time-wait timer, turning off the other 2707 * standard timers. 2708 */ 2709 case TCPS_FIN_WAIT_2: 2710 tp->t_state = TCPS_TIME_WAIT; 2711 tcp_canceltimers(tp); 2712 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * PR_SLOWHZ * tcp_msl); 2713 soisdisconnected(so); 2714 break; 2715 2716 /* 2717 * In TIME_WAIT state restart the 2 MSL time_wait timer. 2718 */ 2719 case TCPS_TIME_WAIT: 2720 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * PR_SLOWHZ * tcp_msl); 2721 break; 2722 } 2723 } 2724 #ifdef TCP_DEBUG 2725 if (so->so_options & SO_DEBUG) 2726 tcp_trace(TA_INPUT, ostate, tp, tcp_saveti, 0); 2727 #endif 2728 2729 /* 2730 * Return any desired output. 2731 */ 2732 if (needoutput || (tp->t_flags & TF_ACKNOW)) { 2733 (void) tcp_output(tp); 2734 } 2735 if (tcp_saveti) 2736 m_freem(tcp_saveti); 2737 return; 2738 2739 badsyn: 2740 /* 2741 * Received a bad SYN. Increment counters and dropwithreset. 2742 */ 2743 TCP_STATINC(TCP_STAT_BADSYN); 2744 tp = NULL; 2745 goto dropwithreset; 2746 2747 dropafterack: 2748 /* 2749 * Generate an ACK dropping incoming segment if it occupies 2750 * sequence space, where the ACK reflects our state. 2751 */ 2752 if (tiflags & TH_RST) 2753 goto drop; 2754 goto dropafterack2; 2755 2756 dropafterack_ratelim: 2757 /* 2758 * We may want to rate-limit ACKs against SYN/RST attack. 2759 */ 2760 if (ppsratecheck(&tcp_ackdrop_ppslim_last, &tcp_ackdrop_ppslim_count, 2761 tcp_ackdrop_ppslim) == 0) { 2762 /* XXX stat */ 2763 goto drop; 2764 } 2765 /* ...fall into dropafterack2... */ 2766 2767 dropafterack2: 2768 m_freem(m); 2769 tp->t_flags |= TF_ACKNOW; 2770 (void) tcp_output(tp); 2771 if (tcp_saveti) 2772 m_freem(tcp_saveti); 2773 return; 2774 2775 dropwithreset_ratelim: 2776 /* 2777 * We may want to rate-limit RSTs in certain situations, 2778 * particularly if we are sending an RST in response to 2779 * an attempt to connect to or otherwise communicate with 2780 * a port for which we have no socket. 2781 */ 2782 if (ppsratecheck(&tcp_rst_ppslim_last, &tcp_rst_ppslim_count, 2783 tcp_rst_ppslim) == 0) { 2784 /* XXX stat */ 2785 goto drop; 2786 } 2787 /* ...fall into dropwithreset... */ 2788 2789 dropwithreset: 2790 /* 2791 * Generate a RST, dropping incoming segment. 2792 * Make ACK acceptable to originator of segment. 2793 */ 2794 if (tiflags & TH_RST) 2795 goto drop; 2796 2797 switch (af) { 2798 #ifdef INET6 2799 case AF_INET6: 2800 /* For following calls to tcp_respond */ 2801 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) 2802 goto drop; 2803 break; 2804 #endif /* INET6 */ 2805 case AF_INET: 2806 if (IN_MULTICAST(ip->ip_dst.s_addr) || 2807 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 2808 goto drop; 2809 } 2810 2811 if (tiflags & TH_ACK) 2812 (void)tcp_respond(tp, m, m, th, (tcp_seq)0, th->th_ack, TH_RST); 2813 else { 2814 if (tiflags & TH_SYN) 2815 tlen++; 2816 (void)tcp_respond(tp, m, m, th, th->th_seq + tlen, (tcp_seq)0, 2817 TH_RST|TH_ACK); 2818 } 2819 if (tcp_saveti) 2820 m_freem(tcp_saveti); 2821 return; 2822 2823 badcsum: 2824 drop: 2825 /* 2826 * Drop space held by incoming segment and return. 2827 */ 2828 if (tp) { 2829 if (tp->t_inpcb) 2830 so = tp->t_inpcb->inp_socket; 2831 #ifdef INET6 2832 else if (tp->t_in6pcb) 2833 so = tp->t_in6pcb->in6p_socket; 2834 #endif 2835 else 2836 so = NULL; 2837 #ifdef TCP_DEBUG 2838 if (so && (so->so_options & SO_DEBUG) != 0) 2839 tcp_trace(TA_DROP, ostate, tp, tcp_saveti, 0); 2840 #endif 2841 } 2842 if (tcp_saveti) 2843 m_freem(tcp_saveti); 2844 m_freem(m); 2845 return; 2846 } 2847 2848 #ifdef TCP_SIGNATURE 2849 int 2850 tcp_signature_apply(void *fstate, void *data, u_int len) 2851 { 2852 2853 MD5Update(fstate, (u_char *)data, len); 2854 return (0); 2855 } 2856 2857 struct secasvar * 2858 tcp_signature_getsav(struct mbuf *m, struct tcphdr *th) 2859 { 2860 struct secasvar *sav; 2861 #ifdef FAST_IPSEC 2862 union sockaddr_union dst; 2863 #endif 2864 struct ip *ip; 2865 struct ip6_hdr *ip6; 2866 2867 ip = mtod(m, struct ip *); 2868 switch (ip->ip_v) { 2869 case 4: 2870 ip = mtod(m, struct ip *); 2871 ip6 = NULL; 2872 break; 2873 case 6: 2874 ip = NULL; 2875 ip6 = mtod(m, struct ip6_hdr *); 2876 break; 2877 default: 2878 return (NULL); 2879 } 2880 2881 #ifdef FAST_IPSEC 2882 /* Extract the destination from the IP header in the mbuf. */ 2883 memset(&dst, 0, sizeof(union sockaddr_union)); 2884 if (ip !=NULL) { 2885 dst.sa.sa_len = sizeof(struct sockaddr_in); 2886 dst.sa.sa_family = AF_INET; 2887 dst.sin.sin_addr = ip->ip_dst; 2888 } else { 2889 dst.sa.sa_len = sizeof(struct sockaddr_in6); 2890 dst.sa.sa_family = AF_INET6; 2891 dst.sin6.sin6_addr = ip6->ip6_dst; 2892 } 2893 2894 /* 2895 * Look up an SADB entry which matches the address of the peer. 2896 */ 2897 sav = KEY_ALLOCSA(&dst, IPPROTO_TCP, htonl(TCP_SIG_SPI)); 2898 #else 2899 if (ip) 2900 sav = key_allocsa(AF_INET, (void *)&ip->ip_src, 2901 (void *)&ip->ip_dst, IPPROTO_TCP, 2902 htonl(TCP_SIG_SPI), 0, 0); 2903 else 2904 sav = key_allocsa(AF_INET6, (void *)&ip6->ip6_src, 2905 (void *)&ip6->ip6_dst, IPPROTO_TCP, 2906 htonl(TCP_SIG_SPI), 0, 0); 2907 #endif 2908 2909 return (sav); /* freesav must be performed by caller */ 2910 } 2911 2912 int 2913 tcp_signature(struct mbuf *m, struct tcphdr *th, int thoff, 2914 struct secasvar *sav, char *sig) 2915 { 2916 MD5_CTX ctx; 2917 struct ip *ip; 2918 struct ipovly *ipovly; 2919 struct ip6_hdr *ip6; 2920 struct ippseudo ippseudo; 2921 struct ip6_hdr_pseudo ip6pseudo; 2922 struct tcphdr th0; 2923 int l, tcphdrlen; 2924 2925 if (sav == NULL) 2926 return (-1); 2927 2928 tcphdrlen = th->th_off * 4; 2929 2930 switch (mtod(m, struct ip *)->ip_v) { 2931 case 4: 2932 ip = mtod(m, struct ip *); 2933 ip6 = NULL; 2934 break; 2935 case 6: 2936 ip = NULL; 2937 ip6 = mtod(m, struct ip6_hdr *); 2938 break; 2939 default: 2940 return (-1); 2941 } 2942 2943 MD5Init(&ctx); 2944 2945 if (ip) { 2946 memset(&ippseudo, 0, sizeof(ippseudo)); 2947 ipovly = (struct ipovly *)ip; 2948 ippseudo.ippseudo_src = ipovly->ih_src; 2949 ippseudo.ippseudo_dst = ipovly->ih_dst; 2950 ippseudo.ippseudo_pad = 0; 2951 ippseudo.ippseudo_p = IPPROTO_TCP; 2952 ippseudo.ippseudo_len = htons(m->m_pkthdr.len - thoff); 2953 MD5Update(&ctx, (char *)&ippseudo, sizeof(ippseudo)); 2954 } else { 2955 memset(&ip6pseudo, 0, sizeof(ip6pseudo)); 2956 ip6pseudo.ip6ph_src = ip6->ip6_src; 2957 in6_clearscope(&ip6pseudo.ip6ph_src); 2958 ip6pseudo.ip6ph_dst = ip6->ip6_dst; 2959 in6_clearscope(&ip6pseudo.ip6ph_dst); 2960 ip6pseudo.ip6ph_len = htons(m->m_pkthdr.len - thoff); 2961 ip6pseudo.ip6ph_nxt = IPPROTO_TCP; 2962 MD5Update(&ctx, (char *)&ip6pseudo, sizeof(ip6pseudo)); 2963 } 2964 2965 th0 = *th; 2966 th0.th_sum = 0; 2967 MD5Update(&ctx, (char *)&th0, sizeof(th0)); 2968 2969 l = m->m_pkthdr.len - thoff - tcphdrlen; 2970 if (l > 0) 2971 m_apply(m, thoff + tcphdrlen, 2972 m->m_pkthdr.len - thoff - tcphdrlen, 2973 tcp_signature_apply, &ctx); 2974 2975 MD5Update(&ctx, _KEYBUF(sav->key_auth), _KEYLEN(sav->key_auth)); 2976 MD5Final(sig, &ctx); 2977 2978 return (0); 2979 } 2980 #endif 2981 2982 static int 2983 tcp_dooptions(struct tcpcb *tp, const u_char *cp, int cnt, 2984 struct tcphdr *th, 2985 struct mbuf *m, int toff, struct tcp_opt_info *oi) 2986 { 2987 u_int16_t mss; 2988 int opt, optlen = 0; 2989 #ifdef TCP_SIGNATURE 2990 void *sigp = NULL; 2991 char sigbuf[TCP_SIGLEN]; 2992 struct secasvar *sav = NULL; 2993 #endif 2994 2995 for (; cp && cnt > 0; cnt -= optlen, cp += optlen) { 2996 opt = cp[0]; 2997 if (opt == TCPOPT_EOL) 2998 break; 2999 if (opt == TCPOPT_NOP) 3000 optlen = 1; 3001 else { 3002 if (cnt < 2) 3003 break; 3004 optlen = cp[1]; 3005 if (optlen < 2 || optlen > cnt) 3006 break; 3007 } 3008 switch (opt) { 3009 3010 default: 3011 continue; 3012 3013 case TCPOPT_MAXSEG: 3014 if (optlen != TCPOLEN_MAXSEG) 3015 continue; 3016 if (!(th->th_flags & TH_SYN)) 3017 continue; 3018 if (TCPS_HAVERCVDSYN(tp->t_state)) 3019 continue; 3020 bcopy(cp + 2, &mss, sizeof(mss)); 3021 oi->maxseg = ntohs(mss); 3022 break; 3023 3024 case TCPOPT_WINDOW: 3025 if (optlen != TCPOLEN_WINDOW) 3026 continue; 3027 if (!(th->th_flags & TH_SYN)) 3028 continue; 3029 if (TCPS_HAVERCVDSYN(tp->t_state)) 3030 continue; 3031 tp->t_flags |= TF_RCVD_SCALE; 3032 tp->requested_s_scale = cp[2]; 3033 if (tp->requested_s_scale > TCP_MAX_WINSHIFT) { 3034 #if 0 /*XXX*/ 3035 char *p; 3036 3037 if (ip) 3038 p = ntohl(ip->ip_src); 3039 #ifdef INET6 3040 else if (ip6) 3041 p = ip6_sprintf(&ip6->ip6_src); 3042 #endif 3043 else 3044 p = "(unknown)"; 3045 log(LOG_ERR, "TCP: invalid wscale %d from %s, " 3046 "assuming %d\n", 3047 tp->requested_s_scale, p, 3048 TCP_MAX_WINSHIFT); 3049 #else 3050 log(LOG_ERR, "TCP: invalid wscale %d, " 3051 "assuming %d\n", 3052 tp->requested_s_scale, 3053 TCP_MAX_WINSHIFT); 3054 #endif 3055 tp->requested_s_scale = TCP_MAX_WINSHIFT; 3056 } 3057 break; 3058 3059 case TCPOPT_TIMESTAMP: 3060 if (optlen != TCPOLEN_TIMESTAMP) 3061 continue; 3062 oi->ts_present = 1; 3063 bcopy(cp + 2, &oi->ts_val, sizeof(oi->ts_val)); 3064 NTOHL(oi->ts_val); 3065 bcopy(cp + 6, &oi->ts_ecr, sizeof(oi->ts_ecr)); 3066 NTOHL(oi->ts_ecr); 3067 3068 if (!(th->th_flags & TH_SYN)) 3069 continue; 3070 if (TCPS_HAVERCVDSYN(tp->t_state)) 3071 continue; 3072 /* 3073 * A timestamp received in a SYN makes 3074 * it ok to send timestamp requests and replies. 3075 */ 3076 tp->t_flags |= TF_RCVD_TSTMP; 3077 tp->ts_recent = oi->ts_val; 3078 tp->ts_recent_age = tcp_now; 3079 break; 3080 3081 case TCPOPT_SACK_PERMITTED: 3082 if (optlen != TCPOLEN_SACK_PERMITTED) 3083 continue; 3084 if (!(th->th_flags & TH_SYN)) 3085 continue; 3086 if (TCPS_HAVERCVDSYN(tp->t_state)) 3087 continue; 3088 if (tcp_do_sack) { 3089 tp->t_flags |= TF_SACK_PERMIT; 3090 tp->t_flags |= TF_WILL_SACK; 3091 } 3092 break; 3093 3094 case TCPOPT_SACK: 3095 tcp_sack_option(tp, th, cp, optlen); 3096 break; 3097 #ifdef TCP_SIGNATURE 3098 case TCPOPT_SIGNATURE: 3099 if (optlen != TCPOLEN_SIGNATURE) 3100 continue; 3101 if (sigp && memcmp(sigp, cp + 2, TCP_SIGLEN)) 3102 return (-1); 3103 3104 sigp = sigbuf; 3105 memcpy(sigbuf, cp + 2, TCP_SIGLEN); 3106 tp->t_flags |= TF_SIGNATURE; 3107 break; 3108 #endif 3109 } 3110 } 3111 3112 #ifdef TCP_SIGNATURE 3113 if (tp->t_flags & TF_SIGNATURE) { 3114 3115 sav = tcp_signature_getsav(m, th); 3116 3117 if (sav == NULL && tp->t_state == TCPS_LISTEN) 3118 return (-1); 3119 } 3120 3121 if ((sigp ? TF_SIGNATURE : 0) ^ (tp->t_flags & TF_SIGNATURE)) { 3122 if (sav == NULL) 3123 return (-1); 3124 #ifdef FAST_IPSEC 3125 KEY_FREESAV(&sav); 3126 #else 3127 key_freesav(sav); 3128 #endif 3129 return (-1); 3130 } 3131 3132 if (sigp) { 3133 char sig[TCP_SIGLEN]; 3134 3135 tcp_fields_to_net(th); 3136 if (tcp_signature(m, th, toff, sav, sig) < 0) { 3137 tcp_fields_to_host(th); 3138 if (sav == NULL) 3139 return (-1); 3140 #ifdef FAST_IPSEC 3141 KEY_FREESAV(&sav); 3142 #else 3143 key_freesav(sav); 3144 #endif 3145 return (-1); 3146 } 3147 tcp_fields_to_host(th); 3148 3149 if (memcmp(sig, sigp, TCP_SIGLEN)) { 3150 TCP_STATINC(TCP_STAT_BADSIG); 3151 if (sav == NULL) 3152 return (-1); 3153 #ifdef FAST_IPSEC 3154 KEY_FREESAV(&sav); 3155 #else 3156 key_freesav(sav); 3157 #endif 3158 return (-1); 3159 } else 3160 TCP_STATINC(TCP_STAT_GOODSIG); 3161 3162 key_sa_recordxfer(sav, m); 3163 #ifdef FAST_IPSEC 3164 KEY_FREESAV(&sav); 3165 #else 3166 key_freesav(sav); 3167 #endif 3168 } 3169 #endif 3170 3171 return (0); 3172 } 3173 3174 /* 3175 * Pull out of band byte out of a segment so 3176 * it doesn't appear in the user's data queue. 3177 * It is still reflected in the segment length for 3178 * sequencing purposes. 3179 */ 3180 void 3181 tcp_pulloutofband(struct socket *so, struct tcphdr *th, 3182 struct mbuf *m, int off) 3183 { 3184 int cnt = off + th->th_urp - 1; 3185 3186 while (cnt >= 0) { 3187 if (m->m_len > cnt) { 3188 char *cp = mtod(m, char *) + cnt; 3189 struct tcpcb *tp = sototcpcb(so); 3190 3191 tp->t_iobc = *cp; 3192 tp->t_oobflags |= TCPOOB_HAVEDATA; 3193 bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); 3194 m->m_len--; 3195 return; 3196 } 3197 cnt -= m->m_len; 3198 m = m->m_next; 3199 if (m == 0) 3200 break; 3201 } 3202 panic("tcp_pulloutofband"); 3203 } 3204 3205 /* 3206 * Collect new round-trip time estimate 3207 * and update averages and current timeout. 3208 */ 3209 void 3210 tcp_xmit_timer(struct tcpcb *tp, uint32_t rtt) 3211 { 3212 int32_t delta; 3213 3214 TCP_STATINC(TCP_STAT_RTTUPDATED); 3215 if (tp->t_srtt != 0) { 3216 /* 3217 * srtt is stored as fixed point with 3 bits after the 3218 * binary point (i.e., scaled by 8). The following magic 3219 * is equivalent to the smoothing algorithm in rfc793 with 3220 * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed 3221 * point). Adjust rtt to origin 0. 3222 */ 3223 delta = (rtt << 2) - (tp->t_srtt >> TCP_RTT_SHIFT); 3224 if ((tp->t_srtt += delta) <= 0) 3225 tp->t_srtt = 1 << 2; 3226 /* 3227 * We accumulate a smoothed rtt variance (actually, a 3228 * smoothed mean difference), then set the retransmit 3229 * timer to smoothed rtt + 4 times the smoothed variance. 3230 * rttvar is stored as fixed point with 2 bits after the 3231 * binary point (scaled by 4). The following is 3232 * equivalent to rfc793 smoothing with an alpha of .75 3233 * (rttvar = rttvar*3/4 + |delta| / 4). This replaces 3234 * rfc793's wired-in beta. 3235 */ 3236 if (delta < 0) 3237 delta = -delta; 3238 delta -= (tp->t_rttvar >> TCP_RTTVAR_SHIFT); 3239 if ((tp->t_rttvar += delta) <= 0) 3240 tp->t_rttvar = 1 << 2; 3241 } else { 3242 /* 3243 * No rtt measurement yet - use the unsmoothed rtt. 3244 * Set the variance to half the rtt (so our first 3245 * retransmit happens at 3*rtt). 3246 */ 3247 tp->t_srtt = rtt << (TCP_RTT_SHIFT + 2); 3248 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT + 2 - 1); 3249 } 3250 tp->t_rtttime = 0; 3251 tp->t_rxtshift = 0; 3252 3253 /* 3254 * the retransmit should happen at rtt + 4 * rttvar. 3255 * Because of the way we do the smoothing, srtt and rttvar 3256 * will each average +1/2 tick of bias. When we compute 3257 * the retransmit timer, we want 1/2 tick of rounding and 3258 * 1 extra tick because of +-1/2 tick uncertainty in the 3259 * firing of the timer. The bias will give us exactly the 3260 * 1.5 tick we need. But, because the bias is 3261 * statistical, we have to test that we don't drop below 3262 * the minimum feasible timer (which is 2 ticks). 3263 */ 3264 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), 3265 max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX); 3266 3267 /* 3268 * We received an ack for a packet that wasn't retransmitted; 3269 * it is probably safe to discard any error indications we've 3270 * received recently. This isn't quite right, but close enough 3271 * for now (a route might have failed after we sent a segment, 3272 * and the return path might not be symmetrical). 3273 */ 3274 tp->t_softerror = 0; 3275 } 3276 3277 3278 /* 3279 * TCP compressed state engine. Currently used to hold compressed 3280 * state for SYN_RECEIVED. 3281 */ 3282 3283 u_long syn_cache_count; 3284 u_int32_t syn_hash1, syn_hash2; 3285 3286 #define SYN_HASH(sa, sp, dp) \ 3287 ((((sa)->s_addr^syn_hash1)*(((((u_int32_t)(dp))<<16) + \ 3288 ((u_int32_t)(sp)))^syn_hash2))) 3289 #ifndef INET6 3290 #define SYN_HASHALL(hash, src, dst) \ 3291 do { \ 3292 hash = SYN_HASH(&((const struct sockaddr_in *)(src))->sin_addr, \ 3293 ((const struct sockaddr_in *)(src))->sin_port, \ 3294 ((const struct sockaddr_in *)(dst))->sin_port); \ 3295 } while (/*CONSTCOND*/ 0) 3296 #else 3297 #define SYN_HASH6(sa, sp, dp) \ 3298 ((((sa)->s6_addr32[0] ^ (sa)->s6_addr32[3] ^ syn_hash1) * \ 3299 (((((u_int32_t)(dp))<<16) + ((u_int32_t)(sp)))^syn_hash2)) \ 3300 & 0x7fffffff) 3301 3302 #define SYN_HASHALL(hash, src, dst) \ 3303 do { \ 3304 switch ((src)->sa_family) { \ 3305 case AF_INET: \ 3306 hash = SYN_HASH(&((const struct sockaddr_in *)(src))->sin_addr, \ 3307 ((const struct sockaddr_in *)(src))->sin_port, \ 3308 ((const struct sockaddr_in *)(dst))->sin_port); \ 3309 break; \ 3310 case AF_INET6: \ 3311 hash = SYN_HASH6(&((const struct sockaddr_in6 *)(src))->sin6_addr, \ 3312 ((const struct sockaddr_in6 *)(src))->sin6_port, \ 3313 ((const struct sockaddr_in6 *)(dst))->sin6_port); \ 3314 break; \ 3315 default: \ 3316 hash = 0; \ 3317 } \ 3318 } while (/*CONSTCOND*/0) 3319 #endif /* INET6 */ 3320 3321 static struct pool syn_cache_pool; 3322 3323 /* 3324 * We don't estimate RTT with SYNs, so each packet starts with the default 3325 * RTT and each timer step has a fixed timeout value. 3326 */ 3327 #define SYN_CACHE_TIMER_ARM(sc) \ 3328 do { \ 3329 TCPT_RANGESET((sc)->sc_rxtcur, \ 3330 TCPTV_SRTTDFLT * tcp_backoff[(sc)->sc_rxtshift], TCPTV_MIN, \ 3331 TCPTV_REXMTMAX); \ 3332 callout_reset(&(sc)->sc_timer, \ 3333 (sc)->sc_rxtcur * (hz / PR_SLOWHZ), syn_cache_timer, (sc)); \ 3334 } while (/*CONSTCOND*/0) 3335 3336 #define SYN_CACHE_TIMESTAMP(sc) (tcp_now - (sc)->sc_timebase) 3337 3338 static inline void 3339 syn_cache_rm(struct syn_cache *sc) 3340 { 3341 TAILQ_REMOVE(&tcp_syn_cache[sc->sc_bucketidx].sch_bucket, 3342 sc, sc_bucketq); 3343 sc->sc_tp = NULL; 3344 LIST_REMOVE(sc, sc_tpq); 3345 tcp_syn_cache[sc->sc_bucketidx].sch_length--; 3346 callout_stop(&sc->sc_timer); 3347 syn_cache_count--; 3348 } 3349 3350 static inline void 3351 syn_cache_put(struct syn_cache *sc) 3352 { 3353 if (sc->sc_ipopts) 3354 (void) m_free(sc->sc_ipopts); 3355 rtcache_free(&sc->sc_route); 3356 if (callout_invoking(&sc->sc_timer)) 3357 sc->sc_flags |= SCF_DEAD; 3358 else { 3359 callout_destroy(&sc->sc_timer); 3360 pool_put(&syn_cache_pool, sc); 3361 } 3362 } 3363 3364 void 3365 syn_cache_init(void) 3366 { 3367 int i; 3368 3369 pool_init(&syn_cache_pool, sizeof(struct syn_cache), 0, 0, 0, 3370 "synpl", NULL, IPL_SOFTNET); 3371 3372 /* Initialize the hash buckets. */ 3373 for (i = 0; i < tcp_syn_cache_size; i++) 3374 TAILQ_INIT(&tcp_syn_cache[i].sch_bucket); 3375 } 3376 3377 void 3378 syn_cache_insert(struct syn_cache *sc, struct tcpcb *tp) 3379 { 3380 struct syn_cache_head *scp; 3381 struct syn_cache *sc2; 3382 int s; 3383 3384 /* 3385 * If there are no entries in the hash table, reinitialize 3386 * the hash secrets. 3387 */ 3388 if (syn_cache_count == 0) { 3389 syn_hash1 = arc4random(); 3390 syn_hash2 = arc4random(); 3391 } 3392 3393 SYN_HASHALL(sc->sc_hash, &sc->sc_src.sa, &sc->sc_dst.sa); 3394 sc->sc_bucketidx = sc->sc_hash % tcp_syn_cache_size; 3395 scp = &tcp_syn_cache[sc->sc_bucketidx]; 3396 3397 /* 3398 * Make sure that we don't overflow the per-bucket 3399 * limit or the total cache size limit. 3400 */ 3401 s = splsoftnet(); 3402 if (scp->sch_length >= tcp_syn_bucket_limit) { 3403 TCP_STATINC(TCP_STAT_SC_BUCKETOVERFLOW); 3404 /* 3405 * The bucket is full. Toss the oldest element in the 3406 * bucket. This will be the first entry in the bucket. 3407 */ 3408 sc2 = TAILQ_FIRST(&scp->sch_bucket); 3409 #ifdef DIAGNOSTIC 3410 /* 3411 * This should never happen; we should always find an 3412 * entry in our bucket. 3413 */ 3414 if (sc2 == NULL) 3415 panic("syn_cache_insert: bucketoverflow: impossible"); 3416 #endif 3417 syn_cache_rm(sc2); 3418 syn_cache_put(sc2); /* calls pool_put but see spl above */ 3419 } else if (syn_cache_count >= tcp_syn_cache_limit) { 3420 struct syn_cache_head *scp2, *sce; 3421 3422 TCP_STATINC(TCP_STAT_SC_OVERFLOWED); 3423 /* 3424 * The cache is full. Toss the oldest entry in the 3425 * first non-empty bucket we can find. 3426 * 3427 * XXX We would really like to toss the oldest 3428 * entry in the cache, but we hope that this 3429 * condition doesn't happen very often. 3430 */ 3431 scp2 = scp; 3432 if (TAILQ_EMPTY(&scp2->sch_bucket)) { 3433 sce = &tcp_syn_cache[tcp_syn_cache_size]; 3434 for (++scp2; scp2 != scp; scp2++) { 3435 if (scp2 >= sce) 3436 scp2 = &tcp_syn_cache[0]; 3437 if (! TAILQ_EMPTY(&scp2->sch_bucket)) 3438 break; 3439 } 3440 #ifdef DIAGNOSTIC 3441 /* 3442 * This should never happen; we should always find a 3443 * non-empty bucket. 3444 */ 3445 if (scp2 == scp) 3446 panic("syn_cache_insert: cacheoverflow: " 3447 "impossible"); 3448 #endif 3449 } 3450 sc2 = TAILQ_FIRST(&scp2->sch_bucket); 3451 syn_cache_rm(sc2); 3452 syn_cache_put(sc2); /* calls pool_put but see spl above */ 3453 } 3454 3455 /* 3456 * Initialize the entry's timer. 3457 */ 3458 sc->sc_rxttot = 0; 3459 sc->sc_rxtshift = 0; 3460 SYN_CACHE_TIMER_ARM(sc); 3461 3462 /* Link it from tcpcb entry */ 3463 LIST_INSERT_HEAD(&tp->t_sc, sc, sc_tpq); 3464 3465 /* Put it into the bucket. */ 3466 TAILQ_INSERT_TAIL(&scp->sch_bucket, sc, sc_bucketq); 3467 scp->sch_length++; 3468 syn_cache_count++; 3469 3470 TCP_STATINC(TCP_STAT_SC_ADDED); 3471 splx(s); 3472 } 3473 3474 /* 3475 * Walk the timer queues, looking for SYN,ACKs that need to be retransmitted. 3476 * If we have retransmitted an entry the maximum number of times, expire 3477 * that entry. 3478 */ 3479 void 3480 syn_cache_timer(void *arg) 3481 { 3482 struct syn_cache *sc = arg; 3483 3484 mutex_enter(softnet_lock); 3485 KERNEL_LOCK(1, NULL); 3486 callout_ack(&sc->sc_timer); 3487 3488 if (__predict_false(sc->sc_flags & SCF_DEAD)) { 3489 TCP_STATINC(TCP_STAT_SC_DELAYED_FREE); 3490 callout_destroy(&sc->sc_timer); 3491 pool_put(&syn_cache_pool, sc); 3492 KERNEL_UNLOCK_ONE(NULL); 3493 mutex_exit(softnet_lock); 3494 return; 3495 } 3496 3497 if (__predict_false(sc->sc_rxtshift == TCP_MAXRXTSHIFT)) { 3498 /* Drop it -- too many retransmissions. */ 3499 goto dropit; 3500 } 3501 3502 /* 3503 * Compute the total amount of time this entry has 3504 * been on a queue. If this entry has been on longer 3505 * than the keep alive timer would allow, expire it. 3506 */ 3507 sc->sc_rxttot += sc->sc_rxtcur; 3508 if (sc->sc_rxttot >= tcp_keepinit) 3509 goto dropit; 3510 3511 TCP_STATINC(TCP_STAT_SC_RETRANSMITTED); 3512 (void) syn_cache_respond(sc, NULL); 3513 3514 /* Advance the timer back-off. */ 3515 sc->sc_rxtshift++; 3516 SYN_CACHE_TIMER_ARM(sc); 3517 3518 KERNEL_UNLOCK_ONE(NULL); 3519 mutex_exit(softnet_lock); 3520 return; 3521 3522 dropit: 3523 TCP_STATINC(TCP_STAT_SC_TIMED_OUT); 3524 syn_cache_rm(sc); 3525 syn_cache_put(sc); /* calls pool_put but see spl above */ 3526 KERNEL_UNLOCK_ONE(NULL); 3527 mutex_exit(softnet_lock); 3528 } 3529 3530 /* 3531 * Remove syn cache created by the specified tcb entry, 3532 * because this does not make sense to keep them 3533 * (if there's no tcb entry, syn cache entry will never be used) 3534 */ 3535 void 3536 syn_cache_cleanup(struct tcpcb *tp) 3537 { 3538 struct syn_cache *sc, *nsc; 3539 int s; 3540 3541 s = splsoftnet(); 3542 3543 for (sc = LIST_FIRST(&tp->t_sc); sc != NULL; sc = nsc) { 3544 nsc = LIST_NEXT(sc, sc_tpq); 3545 3546 #ifdef DIAGNOSTIC 3547 if (sc->sc_tp != tp) 3548 panic("invalid sc_tp in syn_cache_cleanup"); 3549 #endif 3550 syn_cache_rm(sc); 3551 syn_cache_put(sc); /* calls pool_put but see spl above */ 3552 } 3553 /* just for safety */ 3554 LIST_INIT(&tp->t_sc); 3555 3556 splx(s); 3557 } 3558 3559 /* 3560 * Find an entry in the syn cache. 3561 */ 3562 struct syn_cache * 3563 syn_cache_lookup(const struct sockaddr *src, const struct sockaddr *dst, 3564 struct syn_cache_head **headp) 3565 { 3566 struct syn_cache *sc; 3567 struct syn_cache_head *scp; 3568 u_int32_t hash; 3569 int s; 3570 3571 SYN_HASHALL(hash, src, dst); 3572 3573 scp = &tcp_syn_cache[hash % tcp_syn_cache_size]; 3574 *headp = scp; 3575 s = splsoftnet(); 3576 for (sc = TAILQ_FIRST(&scp->sch_bucket); sc != NULL; 3577 sc = TAILQ_NEXT(sc, sc_bucketq)) { 3578 if (sc->sc_hash != hash) 3579 continue; 3580 if (!memcmp(&sc->sc_src, src, src->sa_len) && 3581 !memcmp(&sc->sc_dst, dst, dst->sa_len)) { 3582 splx(s); 3583 return (sc); 3584 } 3585 } 3586 splx(s); 3587 return (NULL); 3588 } 3589 3590 /* 3591 * This function gets called when we receive an ACK for a 3592 * socket in the LISTEN state. We look up the connection 3593 * in the syn cache, and if its there, we pull it out of 3594 * the cache and turn it into a full-blown connection in 3595 * the SYN-RECEIVED state. 3596 * 3597 * The return values may not be immediately obvious, and their effects 3598 * can be subtle, so here they are: 3599 * 3600 * NULL SYN was not found in cache; caller should drop the 3601 * packet and send an RST. 3602 * 3603 * -1 We were unable to create the new connection, and are 3604 * aborting it. An ACK,RST is being sent to the peer 3605 * (unless we got screwey sequence numbners; see below), 3606 * because the 3-way handshake has been completed. Caller 3607 * should not free the mbuf, since we may be using it. If 3608 * we are not, we will free it. 3609 * 3610 * Otherwise, the return value is a pointer to the new socket 3611 * associated with the connection. 3612 */ 3613 struct socket * 3614 syn_cache_get(struct sockaddr *src, struct sockaddr *dst, 3615 struct tcphdr *th, unsigned int hlen, unsigned int tlen, 3616 struct socket *so, struct mbuf *m) 3617 { 3618 struct syn_cache *sc; 3619 struct syn_cache_head *scp; 3620 struct inpcb *inp = NULL; 3621 #ifdef INET6 3622 struct in6pcb *in6p = NULL; 3623 #endif 3624 struct tcpcb *tp = 0; 3625 struct mbuf *am; 3626 int s; 3627 struct socket *oso; 3628 3629 s = splsoftnet(); 3630 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 3631 splx(s); 3632 return (NULL); 3633 } 3634 3635 /* 3636 * Verify the sequence and ack numbers. Try getting the correct 3637 * response again. 3638 */ 3639 if ((th->th_ack != sc->sc_iss + 1) || 3640 SEQ_LEQ(th->th_seq, sc->sc_irs) || 3641 SEQ_GT(th->th_seq, sc->sc_irs + 1 + sc->sc_win)) { 3642 (void) syn_cache_respond(sc, m); 3643 splx(s); 3644 return ((struct socket *)(-1)); 3645 } 3646 3647 /* Remove this cache entry */ 3648 syn_cache_rm(sc); 3649 splx(s); 3650 3651 /* 3652 * Ok, create the full blown connection, and set things up 3653 * as they would have been set up if we had created the 3654 * connection when the SYN arrived. If we can't create 3655 * the connection, abort it. 3656 */ 3657 /* 3658 * inp still has the OLD in_pcb stuff, set the 3659 * v6-related flags on the new guy, too. This is 3660 * done particularly for the case where an AF_INET6 3661 * socket is bound only to a port, and a v4 connection 3662 * comes in on that port. 3663 * we also copy the flowinfo from the original pcb 3664 * to the new one. 3665 */ 3666 oso = so; 3667 so = sonewconn(so, SS_ISCONNECTED); 3668 if (so == NULL) 3669 goto resetandabort; 3670 3671 switch (so->so_proto->pr_domain->dom_family) { 3672 #ifdef INET 3673 case AF_INET: 3674 inp = sotoinpcb(so); 3675 break; 3676 #endif 3677 #ifdef INET6 3678 case AF_INET6: 3679 in6p = sotoin6pcb(so); 3680 break; 3681 #endif 3682 } 3683 switch (src->sa_family) { 3684 #ifdef INET 3685 case AF_INET: 3686 if (inp) { 3687 inp->inp_laddr = ((struct sockaddr_in *)dst)->sin_addr; 3688 inp->inp_lport = ((struct sockaddr_in *)dst)->sin_port; 3689 inp->inp_options = ip_srcroute(); 3690 in_pcbstate(inp, INP_BOUND); 3691 if (inp->inp_options == NULL) { 3692 inp->inp_options = sc->sc_ipopts; 3693 sc->sc_ipopts = NULL; 3694 } 3695 } 3696 #ifdef INET6 3697 else if (in6p) { 3698 /* IPv4 packet to AF_INET6 socket */ 3699 memset(&in6p->in6p_laddr, 0, sizeof(in6p->in6p_laddr)); 3700 in6p->in6p_laddr.s6_addr16[5] = htons(0xffff); 3701 bcopy(&((struct sockaddr_in *)dst)->sin_addr, 3702 &in6p->in6p_laddr.s6_addr32[3], 3703 sizeof(((struct sockaddr_in *)dst)->sin_addr)); 3704 in6p->in6p_lport = ((struct sockaddr_in *)dst)->sin_port; 3705 in6totcpcb(in6p)->t_family = AF_INET; 3706 if (sotoin6pcb(oso)->in6p_flags & IN6P_IPV6_V6ONLY) 3707 in6p->in6p_flags |= IN6P_IPV6_V6ONLY; 3708 else 3709 in6p->in6p_flags &= ~IN6P_IPV6_V6ONLY; 3710 in6_pcbstate(in6p, IN6P_BOUND); 3711 } 3712 #endif 3713 break; 3714 #endif 3715 #ifdef INET6 3716 case AF_INET6: 3717 if (in6p) { 3718 in6p->in6p_laddr = ((struct sockaddr_in6 *)dst)->sin6_addr; 3719 in6p->in6p_lport = ((struct sockaddr_in6 *)dst)->sin6_port; 3720 in6_pcbstate(in6p, IN6P_BOUND); 3721 } 3722 break; 3723 #endif 3724 } 3725 #ifdef INET6 3726 if (in6p && in6totcpcb(in6p)->t_family == AF_INET6 && sotoinpcb(oso)) { 3727 struct in6pcb *oin6p = sotoin6pcb(oso); 3728 /* inherit socket options from the listening socket */ 3729 in6p->in6p_flags |= (oin6p->in6p_flags & IN6P_CONTROLOPTS); 3730 if (in6p->in6p_flags & IN6P_CONTROLOPTS) { 3731 m_freem(in6p->in6p_options); 3732 in6p->in6p_options = 0; 3733 } 3734 ip6_savecontrol(in6p, &in6p->in6p_options, 3735 mtod(m, struct ip6_hdr *), m); 3736 } 3737 #endif 3738 3739 #if defined(IPSEC) || defined(FAST_IPSEC) 3740 /* 3741 * we make a copy of policy, instead of sharing the policy, 3742 * for better behavior in terms of SA lookup and dead SA removal. 3743 */ 3744 if (inp) { 3745 /* copy old policy into new socket's */ 3746 if (ipsec_copy_pcbpolicy(sotoinpcb(oso)->inp_sp, inp->inp_sp)) 3747 printf("tcp_input: could not copy policy\n"); 3748 } 3749 #ifdef INET6 3750 else if (in6p) { 3751 /* copy old policy into new socket's */ 3752 if (ipsec_copy_pcbpolicy(sotoin6pcb(oso)->in6p_sp, 3753 in6p->in6p_sp)) 3754 printf("tcp_input: could not copy policy\n"); 3755 } 3756 #endif 3757 #endif 3758 3759 /* 3760 * Give the new socket our cached route reference. 3761 */ 3762 if (inp) { 3763 rtcache_copy(&inp->inp_route, &sc->sc_route); 3764 rtcache_free(&sc->sc_route); 3765 } 3766 #ifdef INET6 3767 else { 3768 rtcache_copy(&in6p->in6p_route, &sc->sc_route); 3769 rtcache_free(&sc->sc_route); 3770 } 3771 #endif 3772 3773 am = m_get(M_DONTWAIT, MT_SONAME); /* XXX */ 3774 if (am == NULL) 3775 goto resetandabort; 3776 MCLAIM(am, &tcp_mowner); 3777 am->m_len = src->sa_len; 3778 bcopy(src, mtod(am, void *), src->sa_len); 3779 if (inp) { 3780 if (in_pcbconnect(inp, am, &lwp0)) { 3781 (void) m_free(am); 3782 goto resetandabort; 3783 } 3784 } 3785 #ifdef INET6 3786 else if (in6p) { 3787 if (src->sa_family == AF_INET) { 3788 /* IPv4 packet to AF_INET6 socket */ 3789 struct sockaddr_in6 *sin6; 3790 sin6 = mtod(am, struct sockaddr_in6 *); 3791 am->m_len = sizeof(*sin6); 3792 memset(sin6, 0, sizeof(*sin6)); 3793 sin6->sin6_family = AF_INET6; 3794 sin6->sin6_len = sizeof(*sin6); 3795 sin6->sin6_port = ((struct sockaddr_in *)src)->sin_port; 3796 sin6->sin6_addr.s6_addr16[5] = htons(0xffff); 3797 bcopy(&((struct sockaddr_in *)src)->sin_addr, 3798 &sin6->sin6_addr.s6_addr32[3], 3799 sizeof(sin6->sin6_addr.s6_addr32[3])); 3800 } 3801 if (in6_pcbconnect(in6p, am, NULL)) { 3802 (void) m_free(am); 3803 goto resetandabort; 3804 } 3805 } 3806 #endif 3807 else { 3808 (void) m_free(am); 3809 goto resetandabort; 3810 } 3811 (void) m_free(am); 3812 3813 if (inp) 3814 tp = intotcpcb(inp); 3815 #ifdef INET6 3816 else if (in6p) 3817 tp = in6totcpcb(in6p); 3818 #endif 3819 else 3820 tp = NULL; 3821 tp->t_flags = sototcpcb(oso)->t_flags & TF_NODELAY; 3822 if (sc->sc_request_r_scale != 15) { 3823 tp->requested_s_scale = sc->sc_requested_s_scale; 3824 tp->request_r_scale = sc->sc_request_r_scale; 3825 tp->snd_scale = sc->sc_requested_s_scale; 3826 tp->rcv_scale = sc->sc_request_r_scale; 3827 tp->t_flags |= TF_REQ_SCALE|TF_RCVD_SCALE; 3828 } 3829 if (sc->sc_flags & SCF_TIMESTAMP) 3830 tp->t_flags |= TF_REQ_TSTMP|TF_RCVD_TSTMP; 3831 tp->ts_timebase = sc->sc_timebase; 3832 3833 tp->t_template = tcp_template(tp); 3834 if (tp->t_template == 0) { 3835 tp = tcp_drop(tp, ENOBUFS); /* destroys socket */ 3836 so = NULL; 3837 m_freem(m); 3838 goto abort; 3839 } 3840 3841 tp->iss = sc->sc_iss; 3842 tp->irs = sc->sc_irs; 3843 tcp_sendseqinit(tp); 3844 tcp_rcvseqinit(tp); 3845 tp->t_state = TCPS_SYN_RECEIVED; 3846 TCP_TIMER_ARM(tp, TCPT_KEEP, tp->t_keepinit); 3847 TCP_STATINC(TCP_STAT_ACCEPTS); 3848 3849 if ((sc->sc_flags & SCF_SACK_PERMIT) && tcp_do_sack) 3850 tp->t_flags |= TF_WILL_SACK; 3851 3852 if ((sc->sc_flags & SCF_ECN_PERMIT) && tcp_do_ecn) 3853 tp->t_flags |= TF_ECN_PERMIT; 3854 3855 #ifdef TCP_SIGNATURE 3856 if (sc->sc_flags & SCF_SIGNATURE) 3857 tp->t_flags |= TF_SIGNATURE; 3858 #endif 3859 3860 /* Initialize tp->t_ourmss before we deal with the peer's! */ 3861 tp->t_ourmss = sc->sc_ourmaxseg; 3862 tcp_mss_from_peer(tp, sc->sc_peermaxseg); 3863 3864 /* 3865 * Initialize the initial congestion window. If we 3866 * had to retransmit the SYN,ACK, we must initialize cwnd 3867 * to 1 segment (i.e. the Loss Window). 3868 */ 3869 if (sc->sc_rxtshift) 3870 tp->snd_cwnd = tp->t_peermss; 3871 else { 3872 int ss = tcp_init_win; 3873 #ifdef INET 3874 if (inp != NULL && in_localaddr(inp->inp_faddr)) 3875 ss = tcp_init_win_local; 3876 #endif 3877 #ifdef INET6 3878 if (in6p != NULL && in6_localaddr(&in6p->in6p_faddr)) 3879 ss = tcp_init_win_local; 3880 #endif 3881 tp->snd_cwnd = TCP_INITIAL_WINDOW(ss, tp->t_peermss); 3882 } 3883 3884 tcp_rmx_rtt(tp); 3885 tp->snd_wl1 = sc->sc_irs; 3886 tp->rcv_up = sc->sc_irs + 1; 3887 3888 /* 3889 * This is what whould have happened in tcp_output() when 3890 * the SYN,ACK was sent. 3891 */ 3892 tp->snd_up = tp->snd_una; 3893 tp->snd_max = tp->snd_nxt = tp->iss+1; 3894 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 3895 if (sc->sc_win > 0 && SEQ_GT(tp->rcv_nxt + sc->sc_win, tp->rcv_adv)) 3896 tp->rcv_adv = tp->rcv_nxt + sc->sc_win; 3897 tp->last_ack_sent = tp->rcv_nxt; 3898 tp->t_partialacks = -1; 3899 tp->t_dupacks = 0; 3900 3901 TCP_STATINC(TCP_STAT_SC_COMPLETED); 3902 s = splsoftnet(); 3903 syn_cache_put(sc); 3904 splx(s); 3905 return (so); 3906 3907 resetandabort: 3908 (void)tcp_respond(NULL, m, m, th, (tcp_seq)0, th->th_ack, TH_RST); 3909 abort: 3910 if (so != NULL) { 3911 (void) soqremque(so, 1); 3912 (void) soabort(so); 3913 mutex_enter(softnet_lock); 3914 } 3915 s = splsoftnet(); 3916 syn_cache_put(sc); 3917 splx(s); 3918 TCP_STATINC(TCP_STAT_SC_ABORTED); 3919 return ((struct socket *)(-1)); 3920 } 3921 3922 /* 3923 * This function is called when we get a RST for a 3924 * non-existent connection, so that we can see if the 3925 * connection is in the syn cache. If it is, zap it. 3926 */ 3927 3928 void 3929 syn_cache_reset(struct sockaddr *src, struct sockaddr *dst, struct tcphdr *th) 3930 { 3931 struct syn_cache *sc; 3932 struct syn_cache_head *scp; 3933 int s = splsoftnet(); 3934 3935 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 3936 splx(s); 3937 return; 3938 } 3939 if (SEQ_LT(th->th_seq, sc->sc_irs) || 3940 SEQ_GT(th->th_seq, sc->sc_irs+1)) { 3941 splx(s); 3942 return; 3943 } 3944 syn_cache_rm(sc); 3945 TCP_STATINC(TCP_STAT_SC_RESET); 3946 syn_cache_put(sc); /* calls pool_put but see spl above */ 3947 splx(s); 3948 } 3949 3950 void 3951 syn_cache_unreach(const struct sockaddr *src, const struct sockaddr *dst, 3952 struct tcphdr *th) 3953 { 3954 struct syn_cache *sc; 3955 struct syn_cache_head *scp; 3956 int s; 3957 3958 s = splsoftnet(); 3959 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 3960 splx(s); 3961 return; 3962 } 3963 /* If the sequence number != sc_iss, then it's a bogus ICMP msg */ 3964 if (ntohl (th->th_seq) != sc->sc_iss) { 3965 splx(s); 3966 return; 3967 } 3968 3969 /* 3970 * If we've retransmitted 3 times and this is our second error, 3971 * we remove the entry. Otherwise, we allow it to continue on. 3972 * This prevents us from incorrectly nuking an entry during a 3973 * spurious network outage. 3974 * 3975 * See tcp_notify(). 3976 */ 3977 if ((sc->sc_flags & SCF_UNREACH) == 0 || sc->sc_rxtshift < 3) { 3978 sc->sc_flags |= SCF_UNREACH; 3979 splx(s); 3980 return; 3981 } 3982 3983 syn_cache_rm(sc); 3984 TCP_STATINC(TCP_STAT_SC_UNREACH); 3985 syn_cache_put(sc); /* calls pool_put but see spl above */ 3986 splx(s); 3987 } 3988 3989 /* 3990 * Given a LISTEN socket and an inbound SYN request, add 3991 * this to the syn cache, and send back a segment: 3992 * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK> 3993 * to the source. 3994 * 3995 * IMPORTANT NOTE: We do _NOT_ ACK data that might accompany the SYN. 3996 * Doing so would require that we hold onto the data and deliver it 3997 * to the application. However, if we are the target of a SYN-flood 3998 * DoS attack, an attacker could send data which would eventually 3999 * consume all available buffer space if it were ACKed. By not ACKing 4000 * the data, we avoid this DoS scenario. 4001 */ 4002 4003 int 4004 syn_cache_add(struct sockaddr *src, struct sockaddr *dst, struct tcphdr *th, 4005 unsigned int hlen, struct socket *so, struct mbuf *m, u_char *optp, 4006 int optlen, struct tcp_opt_info *oi) 4007 { 4008 struct tcpcb tb, *tp; 4009 long win; 4010 struct syn_cache *sc; 4011 struct syn_cache_head *scp; 4012 struct mbuf *ipopts; 4013 struct tcp_opt_info opti; 4014 int s; 4015 4016 tp = sototcpcb(so); 4017 4018 memset(&opti, 0, sizeof(opti)); 4019 4020 /* 4021 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN 4022 * 4023 * Note this check is performed in tcp_input() very early on. 4024 */ 4025 4026 /* 4027 * Initialize some local state. 4028 */ 4029 win = sbspace(&so->so_rcv); 4030 if (win > TCP_MAXWIN) 4031 win = TCP_MAXWIN; 4032 4033 switch (src->sa_family) { 4034 #ifdef INET 4035 case AF_INET: 4036 /* 4037 * Remember the IP options, if any. 4038 */ 4039 ipopts = ip_srcroute(); 4040 break; 4041 #endif 4042 default: 4043 ipopts = NULL; 4044 } 4045 4046 #ifdef TCP_SIGNATURE 4047 if (optp || (tp->t_flags & TF_SIGNATURE)) 4048 #else 4049 if (optp) 4050 #endif 4051 { 4052 tb.t_flags = tcp_do_rfc1323 ? (TF_REQ_SCALE|TF_REQ_TSTMP) : 0; 4053 #ifdef TCP_SIGNATURE 4054 tb.t_flags |= (tp->t_flags & TF_SIGNATURE); 4055 #endif 4056 tb.t_state = TCPS_LISTEN; 4057 if (tcp_dooptions(&tb, optp, optlen, th, m, m->m_pkthdr.len - 4058 sizeof(struct tcphdr) - optlen - hlen, oi) < 0) 4059 return (0); 4060 } else 4061 tb.t_flags = 0; 4062 4063 /* 4064 * See if we already have an entry for this connection. 4065 * If we do, resend the SYN,ACK. We do not count this 4066 * as a retransmission (XXX though maybe we should). 4067 */ 4068 if ((sc = syn_cache_lookup(src, dst, &scp)) != NULL) { 4069 TCP_STATINC(TCP_STAT_SC_DUPESYN); 4070 if (ipopts) { 4071 /* 4072 * If we were remembering a previous source route, 4073 * forget it and use the new one we've been given. 4074 */ 4075 if (sc->sc_ipopts) 4076 (void) m_free(sc->sc_ipopts); 4077 sc->sc_ipopts = ipopts; 4078 } 4079 sc->sc_timestamp = tb.ts_recent; 4080 if (syn_cache_respond(sc, m) == 0) { 4081 uint64_t *tcps = TCP_STAT_GETREF(); 4082 tcps[TCP_STAT_SNDACKS]++; 4083 tcps[TCP_STAT_SNDTOTAL]++; 4084 TCP_STAT_PUTREF(); 4085 } 4086 return (1); 4087 } 4088 4089 s = splsoftnet(); 4090 sc = pool_get(&syn_cache_pool, PR_NOWAIT); 4091 splx(s); 4092 if (sc == NULL) { 4093 if (ipopts) 4094 (void) m_free(ipopts); 4095 return (0); 4096 } 4097 4098 /* 4099 * Fill in the cache, and put the necessary IP and TCP 4100 * options into the reply. 4101 */ 4102 memset(sc, 0, sizeof(struct syn_cache)); 4103 callout_init(&sc->sc_timer, CALLOUT_MPSAFE); 4104 bcopy(src, &sc->sc_src, src->sa_len); 4105 bcopy(dst, &sc->sc_dst, dst->sa_len); 4106 sc->sc_flags = 0; 4107 sc->sc_ipopts = ipopts; 4108 sc->sc_irs = th->th_seq; 4109 switch (src->sa_family) { 4110 #ifdef INET 4111 case AF_INET: 4112 { 4113 struct sockaddr_in *srcin = (void *) src; 4114 struct sockaddr_in *dstin = (void *) dst; 4115 4116 sc->sc_iss = tcp_new_iss1(&dstin->sin_addr, 4117 &srcin->sin_addr, dstin->sin_port, 4118 srcin->sin_port, sizeof(dstin->sin_addr), 0); 4119 break; 4120 } 4121 #endif /* INET */ 4122 #ifdef INET6 4123 case AF_INET6: 4124 { 4125 struct sockaddr_in6 *srcin6 = (void *) src; 4126 struct sockaddr_in6 *dstin6 = (void *) dst; 4127 4128 sc->sc_iss = tcp_new_iss1(&dstin6->sin6_addr, 4129 &srcin6->sin6_addr, dstin6->sin6_port, 4130 srcin6->sin6_port, sizeof(dstin6->sin6_addr), 0); 4131 break; 4132 } 4133 #endif /* INET6 */ 4134 } 4135 sc->sc_peermaxseg = oi->maxseg; 4136 sc->sc_ourmaxseg = tcp_mss_to_advertise(m->m_flags & M_PKTHDR ? 4137 m->m_pkthdr.rcvif : NULL, 4138 sc->sc_src.sa.sa_family); 4139 sc->sc_win = win; 4140 sc->sc_timebase = tcp_now - 1; /* see tcp_newtcpcb() */ 4141 sc->sc_timestamp = tb.ts_recent; 4142 if ((tb.t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP)) == 4143 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) 4144 sc->sc_flags |= SCF_TIMESTAMP; 4145 if ((tb.t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 4146 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 4147 sc->sc_requested_s_scale = tb.requested_s_scale; 4148 sc->sc_request_r_scale = 0; 4149 /* 4150 * Pick the smallest possible scaling factor that 4151 * will still allow us to scale up to sb_max. 4152 * 4153 * We do this because there are broken firewalls that 4154 * will corrupt the window scale option, leading to 4155 * the other endpoint believing that our advertised 4156 * window is unscaled. At scale factors larger than 4157 * 5 the unscaled window will drop below 1500 bytes, 4158 * leading to serious problems when traversing these 4159 * broken firewalls. 4160 * 4161 * With the default sbmax of 256K, a scale factor 4162 * of 3 will be chosen by this algorithm. Those who 4163 * choose a larger sbmax should watch out 4164 * for the compatiblity problems mentioned above. 4165 * 4166 * RFC1323: The Window field in a SYN (i.e., a <SYN> 4167 * or <SYN,ACK>) segment itself is never scaled. 4168 */ 4169 while (sc->sc_request_r_scale < TCP_MAX_WINSHIFT && 4170 (TCP_MAXWIN << sc->sc_request_r_scale) < sb_max) 4171 sc->sc_request_r_scale++; 4172 } else { 4173 sc->sc_requested_s_scale = 15; 4174 sc->sc_request_r_scale = 15; 4175 } 4176 if ((tb.t_flags & TF_SACK_PERMIT) && tcp_do_sack) 4177 sc->sc_flags |= SCF_SACK_PERMIT; 4178 4179 /* 4180 * ECN setup packet recieved. 4181 */ 4182 if ((th->th_flags & (TH_ECE|TH_CWR)) && tcp_do_ecn) 4183 sc->sc_flags |= SCF_ECN_PERMIT; 4184 4185 #ifdef TCP_SIGNATURE 4186 if (tb.t_flags & TF_SIGNATURE) 4187 sc->sc_flags |= SCF_SIGNATURE; 4188 #endif 4189 sc->sc_tp = tp; 4190 if (syn_cache_respond(sc, m) == 0) { 4191 uint64_t *tcps = TCP_STAT_GETREF(); 4192 tcps[TCP_STAT_SNDACKS]++; 4193 tcps[TCP_STAT_SNDTOTAL]++; 4194 TCP_STAT_PUTREF(); 4195 syn_cache_insert(sc, tp); 4196 } else { 4197 s = splsoftnet(); 4198 syn_cache_put(sc); 4199 splx(s); 4200 TCP_STATINC(TCP_STAT_SC_DROPPED); 4201 } 4202 return (1); 4203 } 4204 4205 int 4206 syn_cache_respond(struct syn_cache *sc, struct mbuf *m) 4207 { 4208 #ifdef INET6 4209 struct rtentry *rt; 4210 #endif 4211 struct route *ro; 4212 u_int8_t *optp; 4213 int optlen, error; 4214 u_int16_t tlen; 4215 struct ip *ip = NULL; 4216 #ifdef INET6 4217 struct ip6_hdr *ip6 = NULL; 4218 #endif 4219 struct tcpcb *tp = NULL; 4220 struct tcphdr *th; 4221 u_int hlen; 4222 struct socket *so; 4223 4224 ro = &sc->sc_route; 4225 switch (sc->sc_src.sa.sa_family) { 4226 case AF_INET: 4227 hlen = sizeof(struct ip); 4228 break; 4229 #ifdef INET6 4230 case AF_INET6: 4231 hlen = sizeof(struct ip6_hdr); 4232 break; 4233 #endif 4234 default: 4235 if (m) 4236 m_freem(m); 4237 return (EAFNOSUPPORT); 4238 } 4239 4240 /* Compute the size of the TCP options. */ 4241 optlen = 4 + (sc->sc_request_r_scale != 15 ? 4 : 0) + 4242 ((sc->sc_flags & SCF_SACK_PERMIT) ? (TCPOLEN_SACK_PERMITTED + 2) : 0) + 4243 #ifdef TCP_SIGNATURE 4244 ((sc->sc_flags & SCF_SIGNATURE) ? (TCPOLEN_SIGNATURE + 2) : 0) + 4245 #endif 4246 ((sc->sc_flags & SCF_TIMESTAMP) ? TCPOLEN_TSTAMP_APPA : 0); 4247 4248 tlen = hlen + sizeof(struct tcphdr) + optlen; 4249 4250 /* 4251 * Create the IP+TCP header from scratch. 4252 */ 4253 if (m) 4254 m_freem(m); 4255 #ifdef DIAGNOSTIC 4256 if (max_linkhdr + tlen > MCLBYTES) 4257 return (ENOBUFS); 4258 #endif 4259 MGETHDR(m, M_DONTWAIT, MT_DATA); 4260 if (m && tlen > MHLEN) { 4261 MCLGET(m, M_DONTWAIT); 4262 if ((m->m_flags & M_EXT) == 0) { 4263 m_freem(m); 4264 m = NULL; 4265 } 4266 } 4267 if (m == NULL) 4268 return (ENOBUFS); 4269 MCLAIM(m, &tcp_tx_mowner); 4270 4271 /* Fixup the mbuf. */ 4272 m->m_data += max_linkhdr; 4273 m->m_len = m->m_pkthdr.len = tlen; 4274 if (sc->sc_tp) { 4275 tp = sc->sc_tp; 4276 if (tp->t_inpcb) 4277 so = tp->t_inpcb->inp_socket; 4278 #ifdef INET6 4279 else if (tp->t_in6pcb) 4280 so = tp->t_in6pcb->in6p_socket; 4281 #endif 4282 else 4283 so = NULL; 4284 } else 4285 so = NULL; 4286 m->m_pkthdr.rcvif = NULL; 4287 memset(mtod(m, u_char *), 0, tlen); 4288 4289 switch (sc->sc_src.sa.sa_family) { 4290 case AF_INET: 4291 ip = mtod(m, struct ip *); 4292 ip->ip_v = 4; 4293 ip->ip_dst = sc->sc_src.sin.sin_addr; 4294 ip->ip_src = sc->sc_dst.sin.sin_addr; 4295 ip->ip_p = IPPROTO_TCP; 4296 th = (struct tcphdr *)(ip + 1); 4297 th->th_dport = sc->sc_src.sin.sin_port; 4298 th->th_sport = sc->sc_dst.sin.sin_port; 4299 break; 4300 #ifdef INET6 4301 case AF_INET6: 4302 ip6 = mtod(m, struct ip6_hdr *); 4303 ip6->ip6_vfc = IPV6_VERSION; 4304 ip6->ip6_dst = sc->sc_src.sin6.sin6_addr; 4305 ip6->ip6_src = sc->sc_dst.sin6.sin6_addr; 4306 ip6->ip6_nxt = IPPROTO_TCP; 4307 /* ip6_plen will be updated in ip6_output() */ 4308 th = (struct tcphdr *)(ip6 + 1); 4309 th->th_dport = sc->sc_src.sin6.sin6_port; 4310 th->th_sport = sc->sc_dst.sin6.sin6_port; 4311 break; 4312 #endif 4313 default: 4314 th = NULL; 4315 } 4316 4317 th->th_seq = htonl(sc->sc_iss); 4318 th->th_ack = htonl(sc->sc_irs + 1); 4319 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 4320 th->th_flags = TH_SYN|TH_ACK; 4321 th->th_win = htons(sc->sc_win); 4322 /* th_sum already 0 */ 4323 /* th_urp already 0 */ 4324 4325 /* Tack on the TCP options. */ 4326 optp = (u_int8_t *)(th + 1); 4327 *optp++ = TCPOPT_MAXSEG; 4328 *optp++ = 4; 4329 *optp++ = (sc->sc_ourmaxseg >> 8) & 0xff; 4330 *optp++ = sc->sc_ourmaxseg & 0xff; 4331 4332 if (sc->sc_request_r_scale != 15) { 4333 *((u_int32_t *)optp) = htonl(TCPOPT_NOP << 24 | 4334 TCPOPT_WINDOW << 16 | TCPOLEN_WINDOW << 8 | 4335 sc->sc_request_r_scale); 4336 optp += 4; 4337 } 4338 4339 if (sc->sc_flags & SCF_TIMESTAMP) { 4340 u_int32_t *lp = (u_int32_t *)(optp); 4341 /* Form timestamp option as shown in appendix A of RFC 1323. */ 4342 *lp++ = htonl(TCPOPT_TSTAMP_HDR); 4343 *lp++ = htonl(SYN_CACHE_TIMESTAMP(sc)); 4344 *lp = htonl(sc->sc_timestamp); 4345 optp += TCPOLEN_TSTAMP_APPA; 4346 } 4347 4348 if (sc->sc_flags & SCF_SACK_PERMIT) { 4349 u_int8_t *p = optp; 4350 4351 /* Let the peer know that we will SACK. */ 4352 p[0] = TCPOPT_SACK_PERMITTED; 4353 p[1] = 2; 4354 p[2] = TCPOPT_NOP; 4355 p[3] = TCPOPT_NOP; 4356 optp += 4; 4357 } 4358 4359 /* 4360 * Send ECN SYN-ACK setup packet. 4361 * Routes can be asymetric, so, even if we receive a packet 4362 * with ECE and CWR set, we must not assume no one will block 4363 * the ECE packet we are about to send. 4364 */ 4365 if ((sc->sc_flags & SCF_ECN_PERMIT) && tp && 4366 SEQ_GEQ(tp->snd_nxt, tp->snd_max)) { 4367 th->th_flags |= TH_ECE; 4368 TCP_STATINC(TCP_STAT_ECN_SHS); 4369 4370 /* 4371 * draft-ietf-tcpm-ecnsyn-00.txt 4372 * 4373 * "[...] a TCP node MAY respond to an ECN-setup 4374 * SYN packet by setting ECT in the responding 4375 * ECN-setup SYN/ACK packet, indicating to routers 4376 * that the SYN/ACK packet is ECN-Capable. 4377 * This allows a congested router along the path 4378 * to mark the packet instead of dropping the 4379 * packet as an indication of congestion." 4380 * 4381 * "[...] There can be a great benefit in setting 4382 * an ECN-capable codepoint in SYN/ACK packets [...] 4383 * Congestion is most likely to occur in 4384 * the server-to-client direction. As a result, 4385 * setting an ECN-capable codepoint in SYN/ACK 4386 * packets can reduce the occurence of three-second 4387 * retransmit timeouts resulting from the drop 4388 * of SYN/ACK packets." 4389 * 4390 * Page 4 and 6, January 2006. 4391 */ 4392 4393 switch (sc->sc_src.sa.sa_family) { 4394 #ifdef INET 4395 case AF_INET: 4396 ip->ip_tos |= IPTOS_ECN_ECT0; 4397 break; 4398 #endif 4399 #ifdef INET6 4400 case AF_INET6: 4401 ip6->ip6_flow |= htonl(IPTOS_ECN_ECT0 << 20); 4402 break; 4403 #endif 4404 } 4405 TCP_STATINC(TCP_STAT_ECN_ECT); 4406 } 4407 4408 #ifdef TCP_SIGNATURE 4409 if (sc->sc_flags & SCF_SIGNATURE) { 4410 struct secasvar *sav; 4411 u_int8_t *sigp; 4412 4413 sav = tcp_signature_getsav(m, th); 4414 4415 if (sav == NULL) { 4416 if (m) 4417 m_freem(m); 4418 return (EPERM); 4419 } 4420 4421 *optp++ = TCPOPT_SIGNATURE; 4422 *optp++ = TCPOLEN_SIGNATURE; 4423 sigp = optp; 4424 memset(optp, 0, TCP_SIGLEN); 4425 optp += TCP_SIGLEN; 4426 *optp++ = TCPOPT_NOP; 4427 *optp++ = TCPOPT_EOL; 4428 4429 (void)tcp_signature(m, th, hlen, sav, sigp); 4430 4431 key_sa_recordxfer(sav, m); 4432 #ifdef FAST_IPSEC 4433 KEY_FREESAV(&sav); 4434 #else 4435 key_freesav(sav); 4436 #endif 4437 } 4438 #endif 4439 4440 /* Compute the packet's checksum. */ 4441 switch (sc->sc_src.sa.sa_family) { 4442 case AF_INET: 4443 ip->ip_len = htons(tlen - hlen); 4444 th->th_sum = 0; 4445 th->th_sum = in4_cksum(m, IPPROTO_TCP, hlen, tlen - hlen); 4446 break; 4447 #ifdef INET6 4448 case AF_INET6: 4449 ip6->ip6_plen = htons(tlen - hlen); 4450 th->th_sum = 0; 4451 th->th_sum = in6_cksum(m, IPPROTO_TCP, hlen, tlen - hlen); 4452 break; 4453 #endif 4454 } 4455 4456 /* 4457 * Fill in some straggling IP bits. Note the stack expects 4458 * ip_len to be in host order, for convenience. 4459 */ 4460 switch (sc->sc_src.sa.sa_family) { 4461 #ifdef INET 4462 case AF_INET: 4463 ip->ip_len = htons(tlen); 4464 ip->ip_ttl = ip_defttl; 4465 /* XXX tos? */ 4466 break; 4467 #endif 4468 #ifdef INET6 4469 case AF_INET6: 4470 ip6->ip6_vfc &= ~IPV6_VERSION_MASK; 4471 ip6->ip6_vfc |= IPV6_VERSION; 4472 ip6->ip6_plen = htons(tlen - hlen); 4473 /* ip6_hlim will be initialized afterwards */ 4474 /* XXX flowlabel? */ 4475 break; 4476 #endif 4477 } 4478 4479 /* XXX use IPsec policy on listening socket, on SYN ACK */ 4480 tp = sc->sc_tp; 4481 4482 switch (sc->sc_src.sa.sa_family) { 4483 #ifdef INET 4484 case AF_INET: 4485 error = ip_output(m, sc->sc_ipopts, ro, 4486 (ip_mtudisc ? IP_MTUDISC : 0), 4487 (struct ip_moptions *)NULL, so); 4488 break; 4489 #endif 4490 #ifdef INET6 4491 case AF_INET6: 4492 ip6->ip6_hlim = in6_selecthlim(NULL, 4493 (rt = rtcache_validate(ro)) != NULL ? rt->rt_ifp 4494 : NULL); 4495 4496 error = ip6_output(m, NULL /*XXX*/, ro, 0, NULL, so, NULL); 4497 break; 4498 #endif 4499 default: 4500 error = EAFNOSUPPORT; 4501 break; 4502 } 4503 return (error); 4504 } 4505