tcp_input.c revision 1.291
1 /* $NetBSD: tcp_input.c,v 1.291 2008/08/04 04:08:47 tls 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 1.291 2008/08/04 04:08:47 tls 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 = 0; 243 int tcp_autorcvbuf_inc = 16 * 1024; 244 int tcp_autorcvbuf_max = 256 * 1024; 245 246 static int tcp_rst_ppslim_count = 0; 247 static struct timeval tcp_rst_ppslim_last; 248 static int tcp_ackdrop_ppslim_count = 0; 249 static struct timeval tcp_ackdrop_ppslim_last; 250 251 #define TCP_PAWS_IDLE (24U * 24 * 60 * 60 * PR_SLOWHZ) 252 253 /* for modulo comparisons of timestamps */ 254 #define TSTMP_LT(a,b) ((int)((a)-(b)) < 0) 255 #define TSTMP_GEQ(a,b) ((int)((a)-(b)) >= 0) 256 257 /* 258 * Neighbor Discovery, Neighbor Unreachability Detection Upper layer hint. 259 */ 260 #ifdef INET6 261 static inline void 262 nd6_hint(struct tcpcb *tp) 263 { 264 struct rtentry *rt; 265 266 if (tp != NULL && tp->t_in6pcb != NULL && tp->t_family == AF_INET6 && 267 (rt = rtcache_validate(&tp->t_in6pcb->in6p_route)) != NULL) 268 nd6_nud_hint(rt, NULL, 0); 269 } 270 #else 271 static inline void 272 nd6_hint(struct tcpcb *tp) 273 { 274 } 275 #endif 276 277 /* 278 * Compute ACK transmission behavior. Delay the ACK unless 279 * we have already delayed an ACK (must send an ACK every two segments). 280 * We also ACK immediately if we received a PUSH and the ACK-on-PUSH 281 * option is enabled. 282 */ 283 static void 284 tcp_setup_ack(struct tcpcb *tp, const struct tcphdr *th) 285 { 286 287 if (tp->t_flags & TF_DELACK || 288 (tcp_ack_on_push && th->th_flags & TH_PUSH)) 289 tp->t_flags |= TF_ACKNOW; 290 else 291 TCP_SET_DELACK(tp); 292 } 293 294 static void 295 icmp_check(struct tcpcb *tp, const struct tcphdr *th, int acked) 296 { 297 298 /* 299 * If we had a pending ICMP message that refers to data that have 300 * just been acknowledged, disregard the recorded ICMP message. 301 */ 302 if ((tp->t_flags & TF_PMTUD_PEND) && 303 SEQ_GT(th->th_ack, tp->t_pmtud_th_seq)) 304 tp->t_flags &= ~TF_PMTUD_PEND; 305 306 /* 307 * Keep track of the largest chunk of data 308 * acknowledged since last PMTU update 309 */ 310 if (tp->t_pmtud_mss_acked < acked) 311 tp->t_pmtud_mss_acked = acked; 312 } 313 314 /* 315 * Convert TCP protocol fields to host order for easier processing. 316 */ 317 static void 318 tcp_fields_to_host(struct tcphdr *th) 319 { 320 321 NTOHL(th->th_seq); 322 NTOHL(th->th_ack); 323 NTOHS(th->th_win); 324 NTOHS(th->th_urp); 325 } 326 327 /* 328 * ... and reverse the above. 329 */ 330 static void 331 tcp_fields_to_net(struct tcphdr *th) 332 { 333 334 HTONL(th->th_seq); 335 HTONL(th->th_ack); 336 HTONS(th->th_win); 337 HTONS(th->th_urp); 338 } 339 340 #ifdef TCP_CSUM_COUNTERS 341 #include <sys/device.h> 342 343 #if defined(INET) 344 extern struct evcnt tcp_hwcsum_ok; 345 extern struct evcnt tcp_hwcsum_bad; 346 extern struct evcnt tcp_hwcsum_data; 347 extern struct evcnt tcp_swcsum; 348 #endif /* defined(INET) */ 349 #if defined(INET6) 350 extern struct evcnt tcp6_hwcsum_ok; 351 extern struct evcnt tcp6_hwcsum_bad; 352 extern struct evcnt tcp6_hwcsum_data; 353 extern struct evcnt tcp6_swcsum; 354 #endif /* defined(INET6) */ 355 356 #define TCP_CSUM_COUNTER_INCR(ev) (ev)->ev_count++ 357 358 #else 359 360 #define TCP_CSUM_COUNTER_INCR(ev) /* nothing */ 361 362 #endif /* TCP_CSUM_COUNTERS */ 363 364 #ifdef TCP_REASS_COUNTERS 365 #include <sys/device.h> 366 367 extern struct evcnt tcp_reass_; 368 extern struct evcnt tcp_reass_empty; 369 extern struct evcnt tcp_reass_iteration[8]; 370 extern struct evcnt tcp_reass_prependfirst; 371 extern struct evcnt tcp_reass_prepend; 372 extern struct evcnt tcp_reass_insert; 373 extern struct evcnt tcp_reass_inserttail; 374 extern struct evcnt tcp_reass_append; 375 extern struct evcnt tcp_reass_appendtail; 376 extern struct evcnt tcp_reass_overlaptail; 377 extern struct evcnt tcp_reass_overlapfront; 378 extern struct evcnt tcp_reass_segdup; 379 extern struct evcnt tcp_reass_fragdup; 380 381 #define TCP_REASS_COUNTER_INCR(ev) (ev)->ev_count++ 382 383 #else 384 385 #define TCP_REASS_COUNTER_INCR(ev) /* nothing */ 386 387 #endif /* TCP_REASS_COUNTERS */ 388 389 static int tcp_reass(struct tcpcb *, const struct tcphdr *, struct mbuf *, 390 int *); 391 static int tcp_dooptions(struct tcpcb *, const u_char *, int, 392 struct tcphdr *, struct mbuf *, int, struct tcp_opt_info *); 393 394 #ifdef INET 395 static void tcp4_log_refused(const struct ip *, const struct tcphdr *); 396 #endif 397 #ifdef INET6 398 static void tcp6_log_refused(const struct ip6_hdr *, const struct tcphdr *); 399 #endif 400 401 #define TRAVERSE(x) while ((x)->m_next) (x) = (x)->m_next 402 403 #if defined(MBUFTRACE) 404 struct mowner tcp_reass_mowner = MOWNER_INIT("tcp", "reass"); 405 #endif /* defined(MBUFTRACE) */ 406 407 static POOL_INIT(tcpipqent_pool, sizeof(struct ipqent), 0, 0, 0, "tcpipqepl", 408 NULL, IPL_VM); 409 410 struct ipqent * 411 tcpipqent_alloc(void) 412 { 413 struct ipqent *ipqe; 414 int s; 415 416 s = splvm(); 417 ipqe = pool_get(&tcpipqent_pool, PR_NOWAIT); 418 splx(s); 419 420 return ipqe; 421 } 422 423 void 424 tcpipqent_free(struct ipqent *ipqe) 425 { 426 int s; 427 428 s = splvm(); 429 pool_put(&tcpipqent_pool, ipqe); 430 splx(s); 431 } 432 433 static int 434 tcp_reass(struct tcpcb *tp, const struct tcphdr *th, struct mbuf *m, int *tlen) 435 { 436 struct ipqent *p, *q, *nq, *tiqe = NULL; 437 struct socket *so = NULL; 438 int pkt_flags; 439 tcp_seq pkt_seq; 440 unsigned pkt_len; 441 u_long rcvpartdupbyte = 0; 442 u_long rcvoobyte; 443 #ifdef TCP_REASS_COUNTERS 444 u_int count = 0; 445 #endif 446 uint64_t *tcps; 447 448 if (tp->t_inpcb) 449 so = tp->t_inpcb->inp_socket; 450 #ifdef INET6 451 else if (tp->t_in6pcb) 452 so = tp->t_in6pcb->in6p_socket; 453 #endif 454 455 TCP_REASS_LOCK_CHECK(tp); 456 457 /* 458 * Call with th==0 after become established to 459 * force pre-ESTABLISHED data up to user socket. 460 */ 461 if (th == 0) 462 goto present; 463 464 m_claimm(m, &tcp_reass_mowner); 465 466 rcvoobyte = *tlen; 467 /* 468 * Copy these to local variables because the tcpiphdr 469 * gets munged while we are collapsing mbufs. 470 */ 471 pkt_seq = th->th_seq; 472 pkt_len = *tlen; 473 pkt_flags = th->th_flags; 474 475 TCP_REASS_COUNTER_INCR(&tcp_reass_); 476 477 if ((p = TAILQ_LAST(&tp->segq, ipqehead)) != NULL) { 478 /* 479 * When we miss a packet, the vast majority of time we get 480 * packets that follow it in order. So optimize for that. 481 */ 482 if (pkt_seq == p->ipqe_seq + p->ipqe_len) { 483 p->ipqe_len += pkt_len; 484 p->ipqe_flags |= pkt_flags; 485 m_cat(p->ipre_mlast, m); 486 TRAVERSE(p->ipre_mlast); 487 m = NULL; 488 tiqe = p; 489 TAILQ_REMOVE(&tp->timeq, p, ipqe_timeq); 490 TCP_REASS_COUNTER_INCR(&tcp_reass_appendtail); 491 goto skip_replacement; 492 } 493 /* 494 * While we're here, if the pkt is completely beyond 495 * anything we have, just insert it at the tail. 496 */ 497 if (SEQ_GT(pkt_seq, p->ipqe_seq + p->ipqe_len)) { 498 TCP_REASS_COUNTER_INCR(&tcp_reass_inserttail); 499 goto insert_it; 500 } 501 } 502 503 q = TAILQ_FIRST(&tp->segq); 504 505 if (q != NULL) { 506 /* 507 * If this segment immediately precedes the first out-of-order 508 * block, simply slap the segment in front of it and (mostly) 509 * skip the complicated logic. 510 */ 511 if (pkt_seq + pkt_len == q->ipqe_seq) { 512 q->ipqe_seq = pkt_seq; 513 q->ipqe_len += pkt_len; 514 q->ipqe_flags |= pkt_flags; 515 m_cat(m, q->ipqe_m); 516 q->ipqe_m = m; 517 q->ipre_mlast = m; /* last mbuf may have changed */ 518 TRAVERSE(q->ipre_mlast); 519 tiqe = q; 520 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 521 TCP_REASS_COUNTER_INCR(&tcp_reass_prependfirst); 522 goto skip_replacement; 523 } 524 } else { 525 TCP_REASS_COUNTER_INCR(&tcp_reass_empty); 526 } 527 528 /* 529 * Find a segment which begins after this one does. 530 */ 531 for (p = NULL; q != NULL; q = nq) { 532 nq = TAILQ_NEXT(q, ipqe_q); 533 #ifdef TCP_REASS_COUNTERS 534 count++; 535 #endif 536 /* 537 * If the received segment is just right after this 538 * fragment, merge the two together and then check 539 * for further overlaps. 540 */ 541 if (q->ipqe_seq + q->ipqe_len == pkt_seq) { 542 #ifdef TCPREASS_DEBUG 543 printf("tcp_reass[%p]: concat %u:%u(%u) to %u:%u(%u)\n", 544 tp, pkt_seq, pkt_seq + pkt_len, pkt_len, 545 q->ipqe_seq, q->ipqe_seq + q->ipqe_len, q->ipqe_len); 546 #endif 547 pkt_len += q->ipqe_len; 548 pkt_flags |= q->ipqe_flags; 549 pkt_seq = q->ipqe_seq; 550 m_cat(q->ipre_mlast, m); 551 TRAVERSE(q->ipre_mlast); 552 m = q->ipqe_m; 553 TCP_REASS_COUNTER_INCR(&tcp_reass_append); 554 goto free_ipqe; 555 } 556 /* 557 * If the received segment is completely past this 558 * fragment, we need to go the next fragment. 559 */ 560 if (SEQ_LT(q->ipqe_seq + q->ipqe_len, pkt_seq)) { 561 p = q; 562 continue; 563 } 564 /* 565 * If the fragment is past the received segment, 566 * it (or any following) can't be concatenated. 567 */ 568 if (SEQ_GT(q->ipqe_seq, pkt_seq + pkt_len)) { 569 TCP_REASS_COUNTER_INCR(&tcp_reass_insert); 570 break; 571 } 572 573 /* 574 * We've received all the data in this segment before. 575 * mark it as a duplicate and return. 576 */ 577 if (SEQ_LEQ(q->ipqe_seq, pkt_seq) && 578 SEQ_GEQ(q->ipqe_seq + q->ipqe_len, pkt_seq + pkt_len)) { 579 tcps = TCP_STAT_GETREF(); 580 tcps[TCP_STAT_RCVDUPPACK]++; 581 tcps[TCP_STAT_RCVDUPBYTE] += pkt_len; 582 TCP_STAT_PUTREF(); 583 tcp_new_dsack(tp, pkt_seq, pkt_len); 584 m_freem(m); 585 if (tiqe != NULL) { 586 tcpipqent_free(tiqe); 587 } 588 TCP_REASS_COUNTER_INCR(&tcp_reass_segdup); 589 return (0); 590 } 591 /* 592 * Received segment completely overlaps this fragment 593 * so we drop the fragment (this keeps the temporal 594 * ordering of segments correct). 595 */ 596 if (SEQ_GEQ(q->ipqe_seq, pkt_seq) && 597 SEQ_LEQ(q->ipqe_seq + q->ipqe_len, pkt_seq + pkt_len)) { 598 rcvpartdupbyte += q->ipqe_len; 599 m_freem(q->ipqe_m); 600 TCP_REASS_COUNTER_INCR(&tcp_reass_fragdup); 601 goto free_ipqe; 602 } 603 /* 604 * RX'ed segment extends past the end of the 605 * fragment. Drop the overlapping bytes. Then 606 * merge the fragment and segment then treat as 607 * a longer received packet. 608 */ 609 if (SEQ_LT(q->ipqe_seq, pkt_seq) && 610 SEQ_GT(q->ipqe_seq + q->ipqe_len, pkt_seq)) { 611 int overlap = q->ipqe_seq + q->ipqe_len - pkt_seq; 612 #ifdef TCPREASS_DEBUG 613 printf("tcp_reass[%p]: trim starting %d bytes of %u:%u(%u)\n", 614 tp, overlap, 615 pkt_seq, pkt_seq + pkt_len, pkt_len); 616 #endif 617 m_adj(m, overlap); 618 rcvpartdupbyte += overlap; 619 m_cat(q->ipre_mlast, m); 620 TRAVERSE(q->ipre_mlast); 621 m = q->ipqe_m; 622 pkt_seq = q->ipqe_seq; 623 pkt_len += q->ipqe_len - overlap; 624 rcvoobyte -= overlap; 625 TCP_REASS_COUNTER_INCR(&tcp_reass_overlaptail); 626 goto free_ipqe; 627 } 628 /* 629 * RX'ed segment extends past the front of the 630 * fragment. Drop the overlapping bytes on the 631 * received packet. The packet will then be 632 * contatentated with this fragment a bit later. 633 */ 634 if (SEQ_GT(q->ipqe_seq, pkt_seq) && 635 SEQ_LT(q->ipqe_seq, pkt_seq + pkt_len)) { 636 int overlap = pkt_seq + pkt_len - q->ipqe_seq; 637 #ifdef TCPREASS_DEBUG 638 printf("tcp_reass[%p]: trim trailing %d bytes of %u:%u(%u)\n", 639 tp, overlap, 640 pkt_seq, pkt_seq + pkt_len, pkt_len); 641 #endif 642 m_adj(m, -overlap); 643 pkt_len -= overlap; 644 rcvpartdupbyte += overlap; 645 TCP_REASS_COUNTER_INCR(&tcp_reass_overlapfront); 646 rcvoobyte -= overlap; 647 } 648 /* 649 * If the received segment immediates precedes this 650 * fragment then tack the fragment onto this segment 651 * and reinsert the data. 652 */ 653 if (q->ipqe_seq == pkt_seq + pkt_len) { 654 #ifdef TCPREASS_DEBUG 655 printf("tcp_reass[%p]: append %u:%u(%u) to %u:%u(%u)\n", 656 tp, q->ipqe_seq, q->ipqe_seq + q->ipqe_len, q->ipqe_len, 657 pkt_seq, pkt_seq + pkt_len, pkt_len); 658 #endif 659 pkt_len += q->ipqe_len; 660 pkt_flags |= q->ipqe_flags; 661 m_cat(m, q->ipqe_m); 662 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 663 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 664 tp->t_segqlen--; 665 KASSERT(tp->t_segqlen >= 0); 666 KASSERT(tp->t_segqlen != 0 || 667 (TAILQ_EMPTY(&tp->segq) && 668 TAILQ_EMPTY(&tp->timeq))); 669 if (tiqe == NULL) { 670 tiqe = q; 671 } else { 672 tcpipqent_free(q); 673 } 674 TCP_REASS_COUNTER_INCR(&tcp_reass_prepend); 675 break; 676 } 677 /* 678 * If the fragment is before the segment, remember it. 679 * When this loop is terminated, p will contain the 680 * pointer to fragment that is right before the received 681 * segment. 682 */ 683 if (SEQ_LEQ(q->ipqe_seq, pkt_seq)) 684 p = q; 685 686 continue; 687 688 /* 689 * This is a common operation. It also will allow 690 * to save doing a malloc/free in most instances. 691 */ 692 free_ipqe: 693 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 694 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 695 tp->t_segqlen--; 696 KASSERT(tp->t_segqlen >= 0); 697 KASSERT(tp->t_segqlen != 0 || 698 (TAILQ_EMPTY(&tp->segq) && TAILQ_EMPTY(&tp->timeq))); 699 if (tiqe == NULL) { 700 tiqe = q; 701 } else { 702 tcpipqent_free(q); 703 } 704 } 705 706 #ifdef TCP_REASS_COUNTERS 707 if (count > 7) 708 TCP_REASS_COUNTER_INCR(&tcp_reass_iteration[0]); 709 else if (count > 0) 710 TCP_REASS_COUNTER_INCR(&tcp_reass_iteration[count]); 711 #endif 712 713 insert_it: 714 715 /* 716 * Allocate a new queue entry since the received segment did not 717 * collapse onto any other out-of-order block; thus we are allocating 718 * a new block. If it had collapsed, tiqe would not be NULL and 719 * we would be reusing it. 720 * XXX If we can't, just drop the packet. XXX 721 */ 722 if (tiqe == NULL) { 723 tiqe = tcpipqent_alloc(); 724 if (tiqe == NULL) { 725 TCP_STATINC(TCP_STAT_RCVMEMDROP); 726 m_freem(m); 727 return (0); 728 } 729 } 730 731 /* 732 * Update the counters. 733 */ 734 tcps = TCP_STAT_GETREF(); 735 tcps[TCP_STAT_RCVOOPACK]++; 736 tcps[TCP_STAT_RCVOOBYTE] += rcvoobyte; 737 if (rcvpartdupbyte) { 738 tcps[TCP_STAT_RCVPARTDUPPACK]++; 739 tcps[TCP_STAT_RCVPARTDUPBYTE] += rcvpartdupbyte; 740 } 741 TCP_STAT_PUTREF(); 742 743 /* 744 * Insert the new fragment queue entry into both queues. 745 */ 746 tiqe->ipqe_m = m; 747 tiqe->ipre_mlast = m; 748 tiqe->ipqe_seq = pkt_seq; 749 tiqe->ipqe_len = pkt_len; 750 tiqe->ipqe_flags = pkt_flags; 751 if (p == NULL) { 752 TAILQ_INSERT_HEAD(&tp->segq, tiqe, ipqe_q); 753 #ifdef TCPREASS_DEBUG 754 if (tiqe->ipqe_seq != tp->rcv_nxt) 755 printf("tcp_reass[%p]: insert %u:%u(%u) at front\n", 756 tp, pkt_seq, pkt_seq + pkt_len, pkt_len); 757 #endif 758 } else { 759 TAILQ_INSERT_AFTER(&tp->segq, p, tiqe, ipqe_q); 760 #ifdef TCPREASS_DEBUG 761 printf("tcp_reass[%p]: insert %u:%u(%u) after %u:%u(%u)\n", 762 tp, pkt_seq, pkt_seq + pkt_len, pkt_len, 763 p->ipqe_seq, p->ipqe_seq + p->ipqe_len, p->ipqe_len); 764 #endif 765 } 766 tp->t_segqlen++; 767 768 skip_replacement: 769 770 TAILQ_INSERT_HEAD(&tp->timeq, tiqe, ipqe_timeq); 771 772 present: 773 /* 774 * Present data to user, advancing rcv_nxt through 775 * completed sequence space. 776 */ 777 if (TCPS_HAVEESTABLISHED(tp->t_state) == 0) 778 return (0); 779 q = TAILQ_FIRST(&tp->segq); 780 if (q == NULL || q->ipqe_seq != tp->rcv_nxt) 781 return (0); 782 if (tp->t_state == TCPS_SYN_RECEIVED && q->ipqe_len) 783 return (0); 784 785 tp->rcv_nxt += q->ipqe_len; 786 pkt_flags = q->ipqe_flags & TH_FIN; 787 nd6_hint(tp); 788 789 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 790 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 791 tp->t_segqlen--; 792 KASSERT(tp->t_segqlen >= 0); 793 KASSERT(tp->t_segqlen != 0 || 794 (TAILQ_EMPTY(&tp->segq) && TAILQ_EMPTY(&tp->timeq))); 795 if (so->so_state & SS_CANTRCVMORE) 796 m_freem(q->ipqe_m); 797 else 798 sbappendstream(&so->so_rcv, q->ipqe_m); 799 tcpipqent_free(q); 800 sorwakeup(so); 801 return (pkt_flags); 802 } 803 804 #ifdef INET6 805 int 806 tcp6_input(struct mbuf **mp, int *offp, int proto) 807 { 808 struct mbuf *m = *mp; 809 810 /* 811 * draft-itojun-ipv6-tcp-to-anycast 812 * better place to put this in? 813 */ 814 if (m->m_flags & M_ANYCAST6) { 815 struct ip6_hdr *ip6; 816 if (m->m_len < sizeof(struct ip6_hdr)) { 817 if ((m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) { 818 TCP_STATINC(TCP_STAT_RCVSHORT); 819 return IPPROTO_DONE; 820 } 821 } 822 ip6 = mtod(m, struct ip6_hdr *); 823 icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR, 824 (char *)&ip6->ip6_dst - (char *)ip6); 825 return IPPROTO_DONE; 826 } 827 828 tcp_input(m, *offp, proto); 829 return IPPROTO_DONE; 830 } 831 #endif 832 833 #ifdef INET 834 static void 835 tcp4_log_refused(const struct ip *ip, const struct tcphdr *th) 836 { 837 char src[4*sizeof "123"]; 838 char dst[4*sizeof "123"]; 839 840 if (ip) { 841 strlcpy(src, inet_ntoa(ip->ip_src), sizeof(src)); 842 strlcpy(dst, inet_ntoa(ip->ip_dst), sizeof(dst)); 843 } 844 else { 845 strlcpy(src, "(unknown)", sizeof(src)); 846 strlcpy(dst, "(unknown)", sizeof(dst)); 847 } 848 log(LOG_INFO, 849 "Connection attempt to TCP %s:%d from %s:%d\n", 850 dst, ntohs(th->th_dport), 851 src, ntohs(th->th_sport)); 852 } 853 #endif 854 855 #ifdef INET6 856 static void 857 tcp6_log_refused(const struct ip6_hdr *ip6, const struct tcphdr *th) 858 { 859 char src[INET6_ADDRSTRLEN]; 860 char dst[INET6_ADDRSTRLEN]; 861 862 if (ip6) { 863 strlcpy(src, ip6_sprintf(&ip6->ip6_src), sizeof(src)); 864 strlcpy(dst, ip6_sprintf(&ip6->ip6_dst), sizeof(dst)); 865 } 866 else { 867 strlcpy(src, "(unknown v6)", sizeof(src)); 868 strlcpy(dst, "(unknown v6)", sizeof(dst)); 869 } 870 log(LOG_INFO, 871 "Connection attempt to TCP [%s]:%d from [%s]:%d\n", 872 dst, ntohs(th->th_dport), 873 src, ntohs(th->th_sport)); 874 } 875 #endif 876 877 /* 878 * Checksum extended TCP header and data. 879 */ 880 int 881 tcp_input_checksum(int af, struct mbuf *m, const struct tcphdr *th, 882 int toff, int off, int tlen) 883 { 884 885 /* 886 * XXX it's better to record and check if this mbuf is 887 * already checked. 888 */ 889 890 switch (af) { 891 #ifdef INET 892 case AF_INET: 893 switch (m->m_pkthdr.csum_flags & 894 ((m->m_pkthdr.rcvif->if_csum_flags_rx & M_CSUM_TCPv4) | 895 M_CSUM_TCP_UDP_BAD | M_CSUM_DATA)) { 896 case M_CSUM_TCPv4|M_CSUM_TCP_UDP_BAD: 897 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_bad); 898 goto badcsum; 899 900 case M_CSUM_TCPv4|M_CSUM_DATA: { 901 u_int32_t hw_csum = m->m_pkthdr.csum_data; 902 903 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_data); 904 if (m->m_pkthdr.csum_flags & M_CSUM_NO_PSEUDOHDR) { 905 const struct ip *ip = 906 mtod(m, const struct ip *); 907 908 hw_csum = in_cksum_phdr(ip->ip_src.s_addr, 909 ip->ip_dst.s_addr, 910 htons(hw_csum + tlen + off + IPPROTO_TCP)); 911 } 912 if ((hw_csum ^ 0xffff) != 0) 913 goto badcsum; 914 break; 915 } 916 917 case M_CSUM_TCPv4: 918 /* Checksum was okay. */ 919 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_ok); 920 break; 921 922 default: 923 /* 924 * Must compute it ourselves. Maybe skip checksum 925 * on loopback interfaces. 926 */ 927 if (__predict_true(!(m->m_pkthdr.rcvif->if_flags & 928 IFF_LOOPBACK) || 929 tcp_do_loopback_cksum)) { 930 TCP_CSUM_COUNTER_INCR(&tcp_swcsum); 931 if (in4_cksum(m, IPPROTO_TCP, toff, 932 tlen + off) != 0) 933 goto badcsum; 934 } 935 break; 936 } 937 break; 938 #endif /* INET4 */ 939 940 #ifdef INET6 941 case AF_INET6: 942 switch (m->m_pkthdr.csum_flags & 943 ((m->m_pkthdr.rcvif->if_csum_flags_rx & M_CSUM_TCPv6) | 944 M_CSUM_TCP_UDP_BAD | M_CSUM_DATA)) { 945 case M_CSUM_TCPv6|M_CSUM_TCP_UDP_BAD: 946 TCP_CSUM_COUNTER_INCR(&tcp6_hwcsum_bad); 947 goto badcsum; 948 949 #if 0 /* notyet */ 950 case M_CSUM_TCPv6|M_CSUM_DATA: 951 #endif 952 953 case M_CSUM_TCPv6: 954 /* Checksum was okay. */ 955 TCP_CSUM_COUNTER_INCR(&tcp6_hwcsum_ok); 956 break; 957 958 default: 959 /* 960 * Must compute it ourselves. Maybe skip checksum 961 * on loopback interfaces. 962 */ 963 if (__predict_true((m->m_flags & M_LOOP) == 0 || 964 tcp_do_loopback_cksum)) { 965 TCP_CSUM_COUNTER_INCR(&tcp6_swcsum); 966 if (in6_cksum(m, IPPROTO_TCP, toff, 967 tlen + off) != 0) 968 goto badcsum; 969 } 970 } 971 break; 972 #endif /* INET6 */ 973 } 974 975 return 0; 976 977 badcsum: 978 TCP_STATINC(TCP_STAT_RCVBADSUM); 979 return -1; 980 } 981 982 /* 983 * TCP input routine, follows pages 65-76 of RFC 793 very closely. 984 */ 985 void 986 tcp_input(struct mbuf *m, ...) 987 { 988 struct tcphdr *th; 989 struct ip *ip; 990 struct inpcb *inp; 991 #ifdef INET6 992 struct ip6_hdr *ip6; 993 struct in6pcb *in6p; 994 #endif 995 u_int8_t *optp = NULL; 996 int optlen = 0; 997 int len, tlen, toff, hdroptlen = 0; 998 struct tcpcb *tp = 0; 999 int tiflags; 1000 struct socket *so = NULL; 1001 int todrop, dupseg, acked, ourfinisacked, needoutput = 0; 1002 #ifdef TCP_DEBUG 1003 short ostate = 0; 1004 #endif 1005 u_long tiwin; 1006 struct tcp_opt_info opti; 1007 int off, iphlen; 1008 va_list ap; 1009 int af; /* af on the wire */ 1010 struct mbuf *tcp_saveti = NULL; 1011 uint32_t ts_rtt; 1012 uint8_t iptos; 1013 uint64_t *tcps; 1014 1015 MCLAIM(m, &tcp_rx_mowner); 1016 va_start(ap, m); 1017 toff = va_arg(ap, int); 1018 (void)va_arg(ap, int); /* ignore value, advance ap */ 1019 va_end(ap); 1020 1021 TCP_STATINC(TCP_STAT_RCVTOTAL); 1022 1023 bzero(&opti, sizeof(opti)); 1024 opti.ts_present = 0; 1025 opti.maxseg = 0; 1026 1027 /* 1028 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN. 1029 * 1030 * TCP is, by definition, unicast, so we reject all 1031 * multicast outright. 1032 * 1033 * Note, there are additional src/dst address checks in 1034 * the AF-specific code below. 1035 */ 1036 if (m->m_flags & (M_BCAST|M_MCAST)) { 1037 /* XXX stat */ 1038 goto drop; 1039 } 1040 #ifdef INET6 1041 if (m->m_flags & M_ANYCAST6) { 1042 /* XXX stat */ 1043 goto drop; 1044 } 1045 #endif 1046 1047 /* 1048 * Get IP and TCP header. 1049 * Note: IP leaves IP header in first mbuf. 1050 */ 1051 ip = mtod(m, struct ip *); 1052 #ifdef INET6 1053 ip6 = NULL; 1054 #endif 1055 switch (ip->ip_v) { 1056 #ifdef INET 1057 case 4: 1058 af = AF_INET; 1059 iphlen = sizeof(struct ip); 1060 ip = mtod(m, struct ip *); 1061 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, 1062 sizeof(struct tcphdr)); 1063 if (th == NULL) { 1064 TCP_STATINC(TCP_STAT_RCVSHORT); 1065 return; 1066 } 1067 /* We do the checksum after PCB lookup... */ 1068 len = ntohs(ip->ip_len); 1069 tlen = len - toff; 1070 iptos = ip->ip_tos; 1071 break; 1072 #endif 1073 #ifdef INET6 1074 case 6: 1075 ip = NULL; 1076 iphlen = sizeof(struct ip6_hdr); 1077 af = AF_INET6; 1078 ip6 = mtod(m, struct ip6_hdr *); 1079 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, 1080 sizeof(struct tcphdr)); 1081 if (th == NULL) { 1082 TCP_STATINC(TCP_STAT_RCVSHORT); 1083 return; 1084 } 1085 1086 /* Be proactive about malicious use of IPv4 mapped address */ 1087 if (IN6_IS_ADDR_V4MAPPED(&ip6->ip6_src) || 1088 IN6_IS_ADDR_V4MAPPED(&ip6->ip6_dst)) { 1089 /* XXX stat */ 1090 goto drop; 1091 } 1092 1093 /* 1094 * Be proactive about unspecified IPv6 address in source. 1095 * As we use all-zero to indicate unbounded/unconnected pcb, 1096 * unspecified IPv6 address can be used to confuse us. 1097 * 1098 * Note that packets with unspecified IPv6 destination is 1099 * already dropped in ip6_input. 1100 */ 1101 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 1102 /* XXX stat */ 1103 goto drop; 1104 } 1105 1106 /* 1107 * Make sure destination address is not multicast. 1108 * Source address checked in ip6_input(). 1109 */ 1110 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) { 1111 /* XXX stat */ 1112 goto drop; 1113 } 1114 1115 /* We do the checksum after PCB lookup... */ 1116 len = m->m_pkthdr.len; 1117 tlen = len - toff; 1118 iptos = (ntohl(ip6->ip6_flow) >> 20) & 0xff; 1119 break; 1120 #endif 1121 default: 1122 m_freem(m); 1123 return; 1124 } 1125 1126 KASSERT(TCP_HDR_ALIGNED_P(th)); 1127 1128 /* 1129 * Check that TCP offset makes sense, 1130 * pull out TCP options and adjust length. XXX 1131 */ 1132 off = th->th_off << 2; 1133 if (off < sizeof (struct tcphdr) || off > tlen) { 1134 TCP_STATINC(TCP_STAT_RCVBADOFF); 1135 goto drop; 1136 } 1137 tlen -= off; 1138 1139 /* 1140 * tcp_input() has been modified to use tlen to mean the TCP data 1141 * length throughout the function. Other functions can use 1142 * m->m_pkthdr.len as the basis for calculating the TCP data length. 1143 * rja 1144 */ 1145 1146 if (off > sizeof (struct tcphdr)) { 1147 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, off); 1148 if (th == NULL) { 1149 TCP_STATINC(TCP_STAT_RCVSHORT); 1150 return; 1151 } 1152 /* 1153 * NOTE: ip/ip6 will not be affected by m_pulldown() 1154 * (as they're before toff) and we don't need to update those. 1155 */ 1156 KASSERT(TCP_HDR_ALIGNED_P(th)); 1157 optlen = off - sizeof (struct tcphdr); 1158 optp = ((u_int8_t *)th) + sizeof(struct tcphdr); 1159 /* 1160 * Do quick retrieval of timestamp options ("options 1161 * prediction?"). If timestamp is the only option and it's 1162 * formatted as recommended in RFC 1323 appendix A, we 1163 * quickly get the values now and not bother calling 1164 * tcp_dooptions(), etc. 1165 */ 1166 if ((optlen == TCPOLEN_TSTAMP_APPA || 1167 (optlen > TCPOLEN_TSTAMP_APPA && 1168 optp[TCPOLEN_TSTAMP_APPA] == TCPOPT_EOL)) && 1169 *(u_int32_t *)optp == htonl(TCPOPT_TSTAMP_HDR) && 1170 (th->th_flags & TH_SYN) == 0) { 1171 opti.ts_present = 1; 1172 opti.ts_val = ntohl(*(u_int32_t *)(optp + 4)); 1173 opti.ts_ecr = ntohl(*(u_int32_t *)(optp + 8)); 1174 optp = NULL; /* we've parsed the options */ 1175 } 1176 } 1177 tiflags = th->th_flags; 1178 1179 /* 1180 * Locate pcb for segment. 1181 */ 1182 findpcb: 1183 inp = NULL; 1184 #ifdef INET6 1185 in6p = NULL; 1186 #endif 1187 switch (af) { 1188 #ifdef INET 1189 case AF_INET: 1190 inp = in_pcblookup_connect(&tcbtable, ip->ip_src, th->th_sport, 1191 ip->ip_dst, th->th_dport); 1192 if (inp == 0) { 1193 TCP_STATINC(TCP_STAT_PCBHASHMISS); 1194 inp = in_pcblookup_bind(&tcbtable, ip->ip_dst, th->th_dport); 1195 } 1196 #ifdef INET6 1197 if (inp == 0) { 1198 struct in6_addr s, d; 1199 1200 /* mapped addr case */ 1201 bzero(&s, sizeof(s)); 1202 s.s6_addr16[5] = htons(0xffff); 1203 bcopy(&ip->ip_src, &s.s6_addr32[3], sizeof(ip->ip_src)); 1204 bzero(&d, sizeof(d)); 1205 d.s6_addr16[5] = htons(0xffff); 1206 bcopy(&ip->ip_dst, &d.s6_addr32[3], sizeof(ip->ip_dst)); 1207 in6p = in6_pcblookup_connect(&tcbtable, &s, 1208 th->th_sport, &d, th->th_dport, 0); 1209 if (in6p == 0) { 1210 TCP_STATINC(TCP_STAT_PCBHASHMISS); 1211 in6p = in6_pcblookup_bind(&tcbtable, &d, 1212 th->th_dport, 0); 1213 } 1214 } 1215 #endif 1216 #ifndef INET6 1217 if (inp == 0) 1218 #else 1219 if (inp == 0 && in6p == 0) 1220 #endif 1221 { 1222 TCP_STATINC(TCP_STAT_NOPORT); 1223 if (tcp_log_refused && 1224 (tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) { 1225 tcp4_log_refused(ip, th); 1226 } 1227 tcp_fields_to_host(th); 1228 goto dropwithreset_ratelim; 1229 } 1230 #if defined(IPSEC) || defined(FAST_IPSEC) 1231 if (inp && (inp->inp_socket->so_options & SO_ACCEPTCONN) == 0 && 1232 ipsec4_in_reject(m, inp)) { 1233 IPSEC_STATINC(IPSEC_STAT_IN_POLVIO); 1234 goto drop; 1235 } 1236 #ifdef INET6 1237 else if (in6p && 1238 (in6p->in6p_socket->so_options & SO_ACCEPTCONN) == 0 && 1239 ipsec6_in_reject_so(m, in6p->in6p_socket)) { 1240 IPSEC_STATINC(IPSEC_STAT_IN_POLVIO); 1241 goto drop; 1242 } 1243 #endif 1244 #endif /*IPSEC*/ 1245 break; 1246 #endif /*INET*/ 1247 #ifdef INET6 1248 case AF_INET6: 1249 { 1250 int faith; 1251 1252 #if defined(NFAITH) && NFAITH > 0 1253 faith = faithprefix(&ip6->ip6_dst); 1254 #else 1255 faith = 0; 1256 #endif 1257 in6p = in6_pcblookup_connect(&tcbtable, &ip6->ip6_src, 1258 th->th_sport, &ip6->ip6_dst, th->th_dport, faith); 1259 if (in6p == NULL) { 1260 TCP_STATINC(TCP_STAT_PCBHASHMISS); 1261 in6p = in6_pcblookup_bind(&tcbtable, &ip6->ip6_dst, 1262 th->th_dport, faith); 1263 } 1264 if (in6p == NULL) { 1265 TCP_STATINC(TCP_STAT_NOPORT); 1266 if (tcp_log_refused && 1267 (tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) { 1268 tcp6_log_refused(ip6, th); 1269 } 1270 tcp_fields_to_host(th); 1271 goto dropwithreset_ratelim; 1272 } 1273 #if defined(IPSEC) || defined(FAST_IPSEC) 1274 if ((in6p->in6p_socket->so_options & SO_ACCEPTCONN) == 0 && 1275 ipsec6_in_reject(m, in6p)) { 1276 IPSEC6_STATINC(IPSEC_STAT_IN_POLVIO); 1277 goto drop; 1278 } 1279 #endif /*IPSEC*/ 1280 break; 1281 } 1282 #endif 1283 } 1284 1285 /* 1286 * If the state is CLOSED (i.e., TCB does not exist) then 1287 * all data in the incoming segment is discarded. 1288 * If the TCB exists but is in CLOSED state, it is embryonic, 1289 * but should either do a listen or a connect soon. 1290 */ 1291 tp = NULL; 1292 so = NULL; 1293 if (inp) { 1294 tp = intotcpcb(inp); 1295 so = inp->inp_socket; 1296 } 1297 #ifdef INET6 1298 else if (in6p) { 1299 tp = in6totcpcb(in6p); 1300 so = in6p->in6p_socket; 1301 } 1302 #endif 1303 if (tp == 0) { 1304 tcp_fields_to_host(th); 1305 goto dropwithreset_ratelim; 1306 } 1307 if (tp->t_state == TCPS_CLOSED) 1308 goto drop; 1309 1310 KASSERT(so->so_lock == softnet_lock); 1311 KASSERT(solocked(so)); 1312 1313 /* 1314 * Checksum extended TCP header and data. 1315 */ 1316 if (tcp_input_checksum(af, m, th, toff, off, tlen)) 1317 goto badcsum; 1318 1319 tcp_fields_to_host(th); 1320 1321 /* Unscale the window into a 32-bit value. */ 1322 if ((tiflags & TH_SYN) == 0) 1323 tiwin = th->th_win << tp->snd_scale; 1324 else 1325 tiwin = th->th_win; 1326 1327 #ifdef INET6 1328 /* save packet options if user wanted */ 1329 if (in6p && (in6p->in6p_flags & IN6P_CONTROLOPTS)) { 1330 if (in6p->in6p_options) { 1331 m_freem(in6p->in6p_options); 1332 in6p->in6p_options = 0; 1333 } 1334 KASSERT(ip6 != NULL); 1335 ip6_savecontrol(in6p, &in6p->in6p_options, ip6, m); 1336 } 1337 #endif 1338 1339 if (so->so_options & (SO_DEBUG|SO_ACCEPTCONN)) { 1340 union syn_cache_sa src; 1341 union syn_cache_sa dst; 1342 1343 bzero(&src, sizeof(src)); 1344 bzero(&dst, sizeof(dst)); 1345 switch (af) { 1346 #ifdef INET 1347 case AF_INET: 1348 src.sin.sin_len = sizeof(struct sockaddr_in); 1349 src.sin.sin_family = AF_INET; 1350 src.sin.sin_addr = ip->ip_src; 1351 src.sin.sin_port = th->th_sport; 1352 1353 dst.sin.sin_len = sizeof(struct sockaddr_in); 1354 dst.sin.sin_family = AF_INET; 1355 dst.sin.sin_addr = ip->ip_dst; 1356 dst.sin.sin_port = th->th_dport; 1357 break; 1358 #endif 1359 #ifdef INET6 1360 case AF_INET6: 1361 src.sin6.sin6_len = sizeof(struct sockaddr_in6); 1362 src.sin6.sin6_family = AF_INET6; 1363 src.sin6.sin6_addr = ip6->ip6_src; 1364 src.sin6.sin6_port = th->th_sport; 1365 1366 dst.sin6.sin6_len = sizeof(struct sockaddr_in6); 1367 dst.sin6.sin6_family = AF_INET6; 1368 dst.sin6.sin6_addr = ip6->ip6_dst; 1369 dst.sin6.sin6_port = th->th_dport; 1370 break; 1371 #endif /* INET6 */ 1372 default: 1373 goto badsyn; /*sanity*/ 1374 } 1375 1376 if (so->so_options & SO_DEBUG) { 1377 #ifdef TCP_DEBUG 1378 ostate = tp->t_state; 1379 #endif 1380 1381 tcp_saveti = NULL; 1382 if (iphlen + sizeof(struct tcphdr) > MHLEN) 1383 goto nosave; 1384 1385 if (m->m_len > iphlen && (m->m_flags & M_EXT) == 0) { 1386 tcp_saveti = m_copym(m, 0, iphlen, M_DONTWAIT); 1387 if (!tcp_saveti) 1388 goto nosave; 1389 } else { 1390 MGETHDR(tcp_saveti, M_DONTWAIT, MT_HEADER); 1391 if (!tcp_saveti) 1392 goto nosave; 1393 MCLAIM(m, &tcp_mowner); 1394 tcp_saveti->m_len = iphlen; 1395 m_copydata(m, 0, iphlen, 1396 mtod(tcp_saveti, void *)); 1397 } 1398 1399 if (M_TRAILINGSPACE(tcp_saveti) < sizeof(struct tcphdr)) { 1400 m_freem(tcp_saveti); 1401 tcp_saveti = NULL; 1402 } else { 1403 tcp_saveti->m_len += sizeof(struct tcphdr); 1404 memcpy(mtod(tcp_saveti, char *) + iphlen, th, 1405 sizeof(struct tcphdr)); 1406 } 1407 nosave:; 1408 } 1409 if (so->so_options & SO_ACCEPTCONN) { 1410 if ((tiflags & (TH_RST|TH_ACK|TH_SYN)) != TH_SYN) { 1411 if (tiflags & TH_RST) { 1412 syn_cache_reset(&src.sa, &dst.sa, th); 1413 } else if ((tiflags & (TH_ACK|TH_SYN)) == 1414 (TH_ACK|TH_SYN)) { 1415 /* 1416 * Received a SYN,ACK. This should 1417 * never happen while we are in 1418 * LISTEN. Send an RST. 1419 */ 1420 goto badsyn; 1421 } else if (tiflags & TH_ACK) { 1422 so = syn_cache_get(&src.sa, &dst.sa, 1423 th, toff, tlen, so, m); 1424 if (so == NULL) { 1425 /* 1426 * We don't have a SYN for 1427 * this ACK; send an RST. 1428 */ 1429 goto badsyn; 1430 } else if (so == 1431 (struct socket *)(-1)) { 1432 /* 1433 * We were unable to create 1434 * the connection. If the 1435 * 3-way handshake was 1436 * completed, and RST has 1437 * been sent to the peer. 1438 * Since the mbuf might be 1439 * in use for the reply, 1440 * do not free it. 1441 */ 1442 m = NULL; 1443 } else { 1444 /* 1445 * We have created a 1446 * full-blown connection. 1447 */ 1448 tp = NULL; 1449 inp = NULL; 1450 #ifdef INET6 1451 in6p = NULL; 1452 #endif 1453 switch (so->so_proto->pr_domain->dom_family) { 1454 #ifdef INET 1455 case AF_INET: 1456 inp = sotoinpcb(so); 1457 tp = intotcpcb(inp); 1458 break; 1459 #endif 1460 #ifdef INET6 1461 case AF_INET6: 1462 in6p = sotoin6pcb(so); 1463 tp = in6totcpcb(in6p); 1464 break; 1465 #endif 1466 } 1467 if (tp == NULL) 1468 goto badsyn; /*XXX*/ 1469 tiwin <<= tp->snd_scale; 1470 goto after_listen; 1471 } 1472 } else { 1473 /* 1474 * None of RST, SYN or ACK was set. 1475 * This is an invalid packet for a 1476 * TCB in LISTEN state. Send a RST. 1477 */ 1478 goto badsyn; 1479 } 1480 } else { 1481 /* 1482 * Received a SYN. 1483 * 1484 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN 1485 */ 1486 if (m->m_flags & (M_BCAST|M_MCAST)) 1487 goto drop; 1488 1489 switch (af) { 1490 #ifdef INET6 1491 case AF_INET6: 1492 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) 1493 goto drop; 1494 break; 1495 #endif /* INET6 */ 1496 case AF_INET: 1497 if (IN_MULTICAST(ip->ip_dst.s_addr) || 1498 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 1499 goto drop; 1500 break; 1501 } 1502 1503 #ifdef INET6 1504 /* 1505 * If deprecated address is forbidden, we do 1506 * not accept SYN to deprecated interface 1507 * address to prevent any new inbound 1508 * connection from getting established. 1509 * When we do not accept SYN, we send a TCP 1510 * RST, with deprecated source address (instead 1511 * of dropping it). We compromise it as it is 1512 * much better for peer to send a RST, and 1513 * RST will be the final packet for the 1514 * exchange. 1515 * 1516 * If we do not forbid deprecated addresses, we 1517 * accept the SYN packet. RFC2462 does not 1518 * suggest dropping SYN in this case. 1519 * If we decipher RFC2462 5.5.4, it says like 1520 * this: 1521 * 1. use of deprecated addr with existing 1522 * communication is okay - "SHOULD continue 1523 * to be used" 1524 * 2. use of it with new communication: 1525 * (2a) "SHOULD NOT be used if alternate 1526 * address with sufficient scope is 1527 * available" 1528 * (2b) nothing mentioned otherwise. 1529 * Here we fall into (2b) case as we have no 1530 * choice in our source address selection - we 1531 * must obey the peer. 1532 * 1533 * The wording in RFC2462 is confusing, and 1534 * there are multiple description text for 1535 * deprecated address handling - worse, they 1536 * are not exactly the same. I believe 5.5.4 1537 * is the best one, so we follow 5.5.4. 1538 */ 1539 if (af == AF_INET6 && !ip6_use_deprecated) { 1540 struct in6_ifaddr *ia6; 1541 if ((ia6 = in6ifa_ifpwithaddr(m->m_pkthdr.rcvif, 1542 &ip6->ip6_dst)) && 1543 (ia6->ia6_flags & IN6_IFF_DEPRECATED)) { 1544 tp = NULL; 1545 goto dropwithreset; 1546 } 1547 } 1548 #endif 1549 1550 #if defined(IPSEC) || defined(FAST_IPSEC) 1551 switch (af) { 1552 #ifdef INET 1553 case AF_INET: 1554 if (ipsec4_in_reject_so(m, so)) { 1555 IPSEC_STATINC(IPSEC_STAT_IN_POLVIO); 1556 tp = NULL; 1557 goto dropwithreset; 1558 } 1559 break; 1560 #endif 1561 #ifdef INET6 1562 case AF_INET6: 1563 if (ipsec6_in_reject_so(m, so)) { 1564 IPSEC6_STATINC(IPSEC_STAT_IN_POLVIO); 1565 tp = NULL; 1566 goto dropwithreset; 1567 } 1568 break; 1569 #endif /*INET6*/ 1570 } 1571 #endif /*IPSEC*/ 1572 1573 /* 1574 * LISTEN socket received a SYN 1575 * from itself? This can't possibly 1576 * be valid; drop the packet. 1577 */ 1578 if (th->th_sport == th->th_dport) { 1579 int i; 1580 1581 switch (af) { 1582 #ifdef INET 1583 case AF_INET: 1584 i = in_hosteq(ip->ip_src, ip->ip_dst); 1585 break; 1586 #endif 1587 #ifdef INET6 1588 case AF_INET6: 1589 i = IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &ip6->ip6_dst); 1590 break; 1591 #endif 1592 default: 1593 i = 1; 1594 } 1595 if (i) { 1596 TCP_STATINC(TCP_STAT_BADSYN); 1597 goto drop; 1598 } 1599 } 1600 1601 /* 1602 * SYN looks ok; create compressed TCP 1603 * state for it. 1604 */ 1605 if (so->so_qlen <= so->so_qlimit && 1606 syn_cache_add(&src.sa, &dst.sa, th, tlen, 1607 so, m, optp, optlen, &opti)) 1608 m = NULL; 1609 } 1610 goto drop; 1611 } 1612 } 1613 1614 after_listen: 1615 #ifdef DIAGNOSTIC 1616 /* 1617 * Should not happen now that all embryonic connections 1618 * are handled with compressed state. 1619 */ 1620 if (tp->t_state == TCPS_LISTEN) 1621 panic("tcp_input: TCPS_LISTEN"); 1622 #endif 1623 1624 /* 1625 * Segment received on connection. 1626 * Reset idle time and keep-alive timer. 1627 */ 1628 tp->t_rcvtime = tcp_now; 1629 if (TCPS_HAVEESTABLISHED(tp->t_state)) 1630 TCP_TIMER_ARM(tp, TCPT_KEEP, tp->t_keepidle); 1631 1632 /* 1633 * Process options. 1634 */ 1635 #ifdef TCP_SIGNATURE 1636 if (optp || (tp->t_flags & TF_SIGNATURE)) 1637 #else 1638 if (optp) 1639 #endif 1640 if (tcp_dooptions(tp, optp, optlen, th, m, toff, &opti) < 0) 1641 goto drop; 1642 1643 if (TCP_SACK_ENABLED(tp)) { 1644 tcp_del_sackholes(tp, th); 1645 } 1646 1647 if (TCP_ECN_ALLOWED(tp)) { 1648 switch (iptos & IPTOS_ECN_MASK) { 1649 case IPTOS_ECN_CE: 1650 tp->t_flags |= TF_ECN_SND_ECE; 1651 TCP_STATINC(TCP_STAT_ECN_CE); 1652 break; 1653 case IPTOS_ECN_ECT0: 1654 TCP_STATINC(TCP_STAT_ECN_ECT); 1655 break; 1656 case IPTOS_ECN_ECT1: 1657 /* XXX: ignore for now -- rpaulo */ 1658 break; 1659 } 1660 1661 if (tiflags & TH_CWR) 1662 tp->t_flags &= ~TF_ECN_SND_ECE; 1663 1664 /* 1665 * Congestion experienced. 1666 * Ignore if we are already trying to recover. 1667 */ 1668 if ((tiflags & TH_ECE) && SEQ_GEQ(tp->snd_una, tp->snd_recover)) 1669 tp->t_congctl->cong_exp(tp); 1670 } 1671 1672 if (opti.ts_present && opti.ts_ecr) { 1673 /* 1674 * Calculate the RTT from the returned time stamp and the 1675 * connection's time base. If the time stamp is later than 1676 * the current time, or is extremely old, fall back to non-1323 1677 * RTT calculation. Since ts_ecr is unsigned, we can test both 1678 * at the same time. 1679 */ 1680 ts_rtt = TCP_TIMESTAMP(tp) - opti.ts_ecr + 1; 1681 if (ts_rtt > TCP_PAWS_IDLE) 1682 ts_rtt = 0; 1683 } else { 1684 ts_rtt = 0; 1685 } 1686 1687 /* 1688 * Header prediction: check for the two common cases 1689 * of a uni-directional data xfer. If the packet has 1690 * no control flags, is in-sequence, the window didn't 1691 * change and we're not retransmitting, it's a 1692 * candidate. If the length is zero and the ack moved 1693 * forward, we're the sender side of the xfer. Just 1694 * free the data acked & wake any higher level process 1695 * that was blocked waiting for space. If the length 1696 * is non-zero and the ack didn't move, we're the 1697 * receiver side. If we're getting packets in-order 1698 * (the reassembly queue is empty), add the data to 1699 * the socket buffer and note that we need a delayed ack. 1700 */ 1701 if (tp->t_state == TCPS_ESTABLISHED && 1702 (tiflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ECE|TH_CWR|TH_ACK)) 1703 == TH_ACK && 1704 (!opti.ts_present || TSTMP_GEQ(opti.ts_val, tp->ts_recent)) && 1705 th->th_seq == tp->rcv_nxt && 1706 tiwin && tiwin == tp->snd_wnd && 1707 tp->snd_nxt == tp->snd_max) { 1708 1709 /* 1710 * If last ACK falls within this segment's sequence numbers, 1711 * record the timestamp. 1712 * NOTE that the test is modified according to the latest 1713 * proposal of the tcplw (at) cray.com list (Braden 1993/04/26). 1714 * 1715 * note that we already know 1716 * TSTMP_GEQ(opti.ts_val, tp->ts_recent) 1717 */ 1718 if (opti.ts_present && 1719 SEQ_LEQ(th->th_seq, tp->last_ack_sent)) { 1720 tp->ts_recent_age = tcp_now; 1721 tp->ts_recent = opti.ts_val; 1722 } 1723 1724 if (tlen == 0) { 1725 /* Ack prediction. */ 1726 if (SEQ_GT(th->th_ack, tp->snd_una) && 1727 SEQ_LEQ(th->th_ack, tp->snd_max) && 1728 tp->snd_cwnd >= tp->snd_wnd && 1729 tp->t_partialacks < 0) { 1730 /* 1731 * this is a pure ack for outstanding data. 1732 */ 1733 if (ts_rtt) 1734 tcp_xmit_timer(tp, ts_rtt); 1735 else if (tp->t_rtttime && 1736 SEQ_GT(th->th_ack, tp->t_rtseq)) 1737 tcp_xmit_timer(tp, 1738 tcp_now - tp->t_rtttime); 1739 acked = th->th_ack - tp->snd_una; 1740 tcps = TCP_STAT_GETREF(); 1741 tcps[TCP_STAT_PREDACK]++; 1742 tcps[TCP_STAT_RCVACKPACK]++; 1743 tcps[TCP_STAT_RCVACKBYTE] += acked; 1744 TCP_STAT_PUTREF(); 1745 nd6_hint(tp); 1746 1747 if (acked > (tp->t_lastoff - tp->t_inoff)) 1748 tp->t_lastm = NULL; 1749 sbdrop(&so->so_snd, acked); 1750 tp->t_lastoff -= acked; 1751 1752 icmp_check(tp, th, acked); 1753 1754 tp->snd_una = th->th_ack; 1755 tp->snd_fack = tp->snd_una; 1756 if (SEQ_LT(tp->snd_high, tp->snd_una)) 1757 tp->snd_high = tp->snd_una; 1758 m_freem(m); 1759 1760 /* 1761 * If all outstanding data are acked, stop 1762 * retransmit timer, otherwise restart timer 1763 * using current (possibly backed-off) value. 1764 * If process is waiting for space, 1765 * wakeup/selnotify/signal. If data 1766 * are ready to send, let tcp_output 1767 * decide between more output or persist. 1768 */ 1769 if (tp->snd_una == tp->snd_max) 1770 TCP_TIMER_DISARM(tp, TCPT_REXMT); 1771 else if (TCP_TIMER_ISARMED(tp, 1772 TCPT_PERSIST) == 0) 1773 TCP_TIMER_ARM(tp, TCPT_REXMT, 1774 tp->t_rxtcur); 1775 1776 sowwakeup(so); 1777 if (so->so_snd.sb_cc) 1778 (void) tcp_output(tp); 1779 if (tcp_saveti) 1780 m_freem(tcp_saveti); 1781 return; 1782 } 1783 } else if (th->th_ack == tp->snd_una && 1784 TAILQ_FIRST(&tp->segq) == NULL && 1785 tlen <= sbspace(&so->so_rcv)) { 1786 int newsize = 0; /* automatic sockbuf scaling */ 1787 1788 /* 1789 * this is a pure, in-sequence data packet 1790 * with nothing on the reassembly queue and 1791 * we have enough buffer space to take it. 1792 */ 1793 tp->rcv_nxt += tlen; 1794 tcps = TCP_STAT_GETREF(); 1795 tcps[TCP_STAT_PREDDAT]++; 1796 tcps[TCP_STAT_RCVPACK]++; 1797 tcps[TCP_STAT_RCVBYTE] += tlen; 1798 TCP_STAT_PUTREF(); 1799 nd6_hint(tp); 1800 1801 /* 1802 * Automatic sizing enables the performance of large buffers 1803 * and most of the efficiency of small ones by only allocating 1804 * space when it is needed. 1805 * 1806 * On the receive side the socket buffer memory is only rarely 1807 * used to any significant extent. This allows us to be much 1808 * more aggressive in scaling the receive socket buffer. For 1809 * the case that the buffer space is actually used to a large 1810 * extent and we run out of kernel memory we can simply drop 1811 * the new segments; TCP on the sender will just retransmit it 1812 * later. Setting the buffer size too big may only consume too 1813 * much kernel memory if the application doesn't read() from 1814 * the socket or packet loss or reordering makes use of the 1815 * reassembly queue. 1816 * 1817 * The criteria to step up the receive buffer one notch are: 1818 * 1. the number of bytes received during the time it takes 1819 * one timestamp to be reflected back to us (the RTT); 1820 * 2. received bytes per RTT is within seven eighth of the 1821 * current socket buffer size; 1822 * 3. receive buffer size has not hit maximal automatic size; 1823 * 1824 * This algorithm does one step per RTT at most and only if 1825 * we receive a bulk stream w/o packet losses or reorderings. 1826 * Shrinking the buffer during idle times is not necessary as 1827 * it doesn't consume any memory when idle. 1828 * 1829 * TODO: Only step up if the application is actually serving 1830 * the buffer to better manage the socket buffer resources. 1831 */ 1832 if (tcp_do_autorcvbuf && 1833 opti.ts_ecr && 1834 (so->so_rcv.sb_flags & SB_AUTOSIZE)) { 1835 if (opti.ts_ecr > tp->rfbuf_ts && 1836 opti.ts_ecr - tp->rfbuf_ts < PR_SLOWHZ) { 1837 if (tp->rfbuf_cnt > 1838 (so->so_rcv.sb_hiwat / 8 * 7) && 1839 so->so_rcv.sb_hiwat < 1840 tcp_autorcvbuf_max) { 1841 newsize = 1842 min(so->so_rcv.sb_hiwat + 1843 tcp_autorcvbuf_inc, 1844 tcp_autorcvbuf_max); 1845 } 1846 /* Start over with next RTT. */ 1847 tp->rfbuf_ts = 0; 1848 tp->rfbuf_cnt = 0; 1849 } else 1850 tp->rfbuf_cnt += tlen; /* add up */ 1851 } 1852 1853 /* 1854 * Drop TCP, IP headers and TCP options then add data 1855 * to socket buffer. 1856 */ 1857 if (so->so_state & SS_CANTRCVMORE) 1858 m_freem(m); 1859 else { 1860 /* 1861 * Set new socket buffer size. 1862 * Give up when limit is reached. 1863 */ 1864 if (newsize) 1865 if (!sbreserve(&so->so_rcv, 1866 newsize, so)) 1867 so->so_rcv.sb_flags &= ~SB_AUTOSIZE; 1868 m_adj(m, toff + off); 1869 sbappendstream(&so->so_rcv, m); 1870 } 1871 sorwakeup(so); 1872 tcp_setup_ack(tp, th); 1873 if (tp->t_flags & TF_ACKNOW) 1874 (void) tcp_output(tp); 1875 if (tcp_saveti) 1876 m_freem(tcp_saveti); 1877 return; 1878 } 1879 } 1880 1881 /* 1882 * Compute mbuf offset to TCP data segment. 1883 */ 1884 hdroptlen = toff + off; 1885 1886 /* 1887 * Calculate amount of space in receive window, 1888 * and then do TCP input processing. 1889 * Receive window is amount of space in rcv queue, 1890 * but not less than advertised window. 1891 */ 1892 { int win; 1893 1894 win = sbspace(&so->so_rcv); 1895 if (win < 0) 1896 win = 0; 1897 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 1898 } 1899 1900 /* Reset receive buffer auto scaling when not in bulk receive mode. */ 1901 tp->rfbuf_ts = 0; 1902 tp->rfbuf_cnt = 0; 1903 1904 switch (tp->t_state) { 1905 /* 1906 * If the state is SYN_SENT: 1907 * if seg contains an ACK, but not for our SYN, drop the input. 1908 * if seg contains a RST, then drop the connection. 1909 * if seg does not contain SYN, then drop it. 1910 * Otherwise this is an acceptable SYN segment 1911 * initialize tp->rcv_nxt and tp->irs 1912 * if seg contains ack then advance tp->snd_una 1913 * if seg contains a ECE and ECN support is enabled, the stream 1914 * is ECN capable. 1915 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 1916 * arrange for segment to be acked (eventually) 1917 * continue processing rest of data/controls, beginning with URG 1918 */ 1919 case TCPS_SYN_SENT: 1920 if ((tiflags & TH_ACK) && 1921 (SEQ_LEQ(th->th_ack, tp->iss) || 1922 SEQ_GT(th->th_ack, tp->snd_max))) 1923 goto dropwithreset; 1924 if (tiflags & TH_RST) { 1925 if (tiflags & TH_ACK) 1926 tp = tcp_drop(tp, ECONNREFUSED); 1927 goto drop; 1928 } 1929 if ((tiflags & TH_SYN) == 0) 1930 goto drop; 1931 if (tiflags & TH_ACK) { 1932 tp->snd_una = th->th_ack; 1933 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 1934 tp->snd_nxt = tp->snd_una; 1935 if (SEQ_LT(tp->snd_high, tp->snd_una)) 1936 tp->snd_high = tp->snd_una; 1937 TCP_TIMER_DISARM(tp, TCPT_REXMT); 1938 1939 if ((tiflags & TH_ECE) && tcp_do_ecn) { 1940 tp->t_flags |= TF_ECN_PERMIT; 1941 TCP_STATINC(TCP_STAT_ECN_SHS); 1942 } 1943 1944 } 1945 tp->irs = th->th_seq; 1946 tcp_rcvseqinit(tp); 1947 tp->t_flags |= TF_ACKNOW; 1948 tcp_mss_from_peer(tp, opti.maxseg); 1949 1950 /* 1951 * Initialize the initial congestion window. If we 1952 * had to retransmit the SYN, we must initialize cwnd 1953 * to 1 segment (i.e. the Loss Window). 1954 */ 1955 if (tp->t_flags & TF_SYN_REXMT) 1956 tp->snd_cwnd = tp->t_peermss; 1957 else { 1958 int ss = tcp_init_win; 1959 #ifdef INET 1960 if (inp != NULL && in_localaddr(inp->inp_faddr)) 1961 ss = tcp_init_win_local; 1962 #endif 1963 #ifdef INET6 1964 if (in6p != NULL && in6_localaddr(&in6p->in6p_faddr)) 1965 ss = tcp_init_win_local; 1966 #endif 1967 tp->snd_cwnd = TCP_INITIAL_WINDOW(ss, tp->t_peermss); 1968 } 1969 1970 tcp_rmx_rtt(tp); 1971 if (tiflags & TH_ACK) { 1972 TCP_STATINC(TCP_STAT_CONNECTS); 1973 soisconnected(so); 1974 tcp_established(tp); 1975 /* Do window scaling on this connection? */ 1976 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 1977 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 1978 tp->snd_scale = tp->requested_s_scale; 1979 tp->rcv_scale = tp->request_r_scale; 1980 } 1981 TCP_REASS_LOCK(tp); 1982 (void) tcp_reass(tp, NULL, (struct mbuf *)0, &tlen); 1983 TCP_REASS_UNLOCK(tp); 1984 /* 1985 * if we didn't have to retransmit the SYN, 1986 * use its rtt as our initial srtt & rtt var. 1987 */ 1988 if (tp->t_rtttime) 1989 tcp_xmit_timer(tp, tcp_now - tp->t_rtttime); 1990 } else 1991 tp->t_state = TCPS_SYN_RECEIVED; 1992 1993 /* 1994 * Advance th->th_seq to correspond to first data byte. 1995 * If data, trim to stay within window, 1996 * dropping FIN if necessary. 1997 */ 1998 th->th_seq++; 1999 if (tlen > tp->rcv_wnd) { 2000 todrop = tlen - tp->rcv_wnd; 2001 m_adj(m, -todrop); 2002 tlen = tp->rcv_wnd; 2003 tiflags &= ~TH_FIN; 2004 tcps = TCP_STAT_GETREF(); 2005 tcps[TCP_STAT_RCVPACKAFTERWIN]++; 2006 tcps[TCP_STAT_RCVBYTEAFTERWIN] += todrop; 2007 TCP_STAT_PUTREF(); 2008 } 2009 tp->snd_wl1 = th->th_seq - 1; 2010 tp->rcv_up = th->th_seq; 2011 goto step6; 2012 2013 /* 2014 * If the state is SYN_RECEIVED: 2015 * If seg contains an ACK, but not for our SYN, drop the input 2016 * and generate an RST. See page 36, rfc793 2017 */ 2018 case TCPS_SYN_RECEIVED: 2019 if ((tiflags & TH_ACK) && 2020 (SEQ_LEQ(th->th_ack, tp->iss) || 2021 SEQ_GT(th->th_ack, tp->snd_max))) 2022 goto dropwithreset; 2023 break; 2024 } 2025 2026 /* 2027 * States other than LISTEN or SYN_SENT. 2028 * First check timestamp, if present. 2029 * Then check that at least some bytes of segment are within 2030 * receive window. If segment begins before rcv_nxt, 2031 * drop leading data (and SYN); if nothing left, just ack. 2032 * 2033 * RFC 1323 PAWS: If we have a timestamp reply on this segment 2034 * and it's less than ts_recent, drop it. 2035 */ 2036 if (opti.ts_present && (tiflags & TH_RST) == 0 && tp->ts_recent && 2037 TSTMP_LT(opti.ts_val, tp->ts_recent)) { 2038 2039 /* Check to see if ts_recent is over 24 days old. */ 2040 if (tcp_now - tp->ts_recent_age > TCP_PAWS_IDLE) { 2041 /* 2042 * Invalidate ts_recent. If this segment updates 2043 * ts_recent, the age will be reset later and ts_recent 2044 * will get a valid value. If it does not, setting 2045 * ts_recent to zero will at least satisfy the 2046 * requirement that zero be placed in the timestamp 2047 * echo reply when ts_recent isn't valid. The 2048 * age isn't reset until we get a valid ts_recent 2049 * because we don't want out-of-order segments to be 2050 * dropped when ts_recent is old. 2051 */ 2052 tp->ts_recent = 0; 2053 } else { 2054 tcps = TCP_STAT_GETREF(); 2055 tcps[TCP_STAT_RCVDUPPACK]++; 2056 tcps[TCP_STAT_RCVDUPBYTE] += tlen; 2057 tcps[TCP_STAT_PAWSDROP]++; 2058 TCP_STAT_PUTREF(); 2059 tcp_new_dsack(tp, th->th_seq, tlen); 2060 goto dropafterack; 2061 } 2062 } 2063 2064 todrop = tp->rcv_nxt - th->th_seq; 2065 dupseg = false; 2066 if (todrop > 0) { 2067 if (tiflags & TH_SYN) { 2068 tiflags &= ~TH_SYN; 2069 th->th_seq++; 2070 if (th->th_urp > 1) 2071 th->th_urp--; 2072 else { 2073 tiflags &= ~TH_URG; 2074 th->th_urp = 0; 2075 } 2076 todrop--; 2077 } 2078 if (todrop > tlen || 2079 (todrop == tlen && (tiflags & TH_FIN) == 0)) { 2080 /* 2081 * Any valid FIN or RST must be to the left of the 2082 * window. At this point the FIN or RST must be a 2083 * duplicate or out of sequence; drop it. 2084 */ 2085 if (tiflags & TH_RST) 2086 goto drop; 2087 tiflags &= ~(TH_FIN|TH_RST); 2088 /* 2089 * Send an ACK to resynchronize and drop any data. 2090 * But keep on processing for RST or ACK. 2091 */ 2092 tp->t_flags |= TF_ACKNOW; 2093 todrop = tlen; 2094 dupseg = true; 2095 tcps = TCP_STAT_GETREF(); 2096 tcps[TCP_STAT_RCVDUPPACK]++; 2097 tcps[TCP_STAT_RCVDUPBYTE] += todrop; 2098 TCP_STAT_PUTREF(); 2099 } else if ((tiflags & TH_RST) && 2100 th->th_seq != tp->last_ack_sent) { 2101 /* 2102 * Test for reset before adjusting the sequence 2103 * number for overlapping data. 2104 */ 2105 goto dropafterack_ratelim; 2106 } else { 2107 tcps = TCP_STAT_GETREF(); 2108 tcps[TCP_STAT_RCVPARTDUPPACK]++; 2109 tcps[TCP_STAT_RCVPARTDUPBYTE] += todrop; 2110 TCP_STAT_PUTREF(); 2111 } 2112 tcp_new_dsack(tp, th->th_seq, todrop); 2113 hdroptlen += todrop; /*drop from head afterwards*/ 2114 th->th_seq += todrop; 2115 tlen -= todrop; 2116 if (th->th_urp > todrop) 2117 th->th_urp -= todrop; 2118 else { 2119 tiflags &= ~TH_URG; 2120 th->th_urp = 0; 2121 } 2122 } 2123 2124 /* 2125 * If new data are received on a connection after the 2126 * user processes are gone, then RST the other end. 2127 */ 2128 if ((so->so_state & SS_NOFDREF) && 2129 tp->t_state > TCPS_CLOSE_WAIT && tlen) { 2130 tp = tcp_close(tp); 2131 TCP_STATINC(TCP_STAT_RCVAFTERCLOSE); 2132 goto dropwithreset; 2133 } 2134 2135 /* 2136 * If segment ends after window, drop trailing data 2137 * (and PUSH and FIN); if nothing left, just ACK. 2138 */ 2139 todrop = (th->th_seq + tlen) - (tp->rcv_nxt+tp->rcv_wnd); 2140 if (todrop > 0) { 2141 TCP_STATINC(TCP_STAT_RCVPACKAFTERWIN); 2142 if (todrop >= tlen) { 2143 /* 2144 * The segment actually starts after the window. 2145 * th->th_seq + tlen - tp->rcv_nxt - tp->rcv_wnd >= tlen 2146 * th->th_seq - tp->rcv_nxt - tp->rcv_wnd >= 0 2147 * th->th_seq >= tp->rcv_nxt + tp->rcv_wnd 2148 */ 2149 TCP_STATADD(TCP_STAT_RCVBYTEAFTERWIN, tlen); 2150 /* 2151 * If a new connection request is received 2152 * while in TIME_WAIT, drop the old connection 2153 * and start over if the sequence numbers 2154 * are above the previous ones. 2155 * 2156 * NOTE: We will checksum the packet again, and 2157 * so we need to put the header fields back into 2158 * network order! 2159 * XXX This kind of sucks, but we don't expect 2160 * XXX this to happen very often, so maybe it 2161 * XXX doesn't matter so much. 2162 */ 2163 if (tiflags & TH_SYN && 2164 tp->t_state == TCPS_TIME_WAIT && 2165 SEQ_GT(th->th_seq, tp->rcv_nxt)) { 2166 tp = tcp_close(tp); 2167 tcp_fields_to_net(th); 2168 goto findpcb; 2169 } 2170 /* 2171 * If window is closed can only take segments at 2172 * window edge, and have to drop data and PUSH from 2173 * incoming segments. Continue processing, but 2174 * remember to ack. Otherwise, drop segment 2175 * and (if not RST) ack. 2176 */ 2177 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 2178 tp->t_flags |= TF_ACKNOW; 2179 TCP_STATINC(TCP_STAT_RCVWINPROBE); 2180 } else 2181 goto dropafterack; 2182 } else 2183 TCP_STATADD(TCP_STAT_RCVBYTEAFTERWIN, todrop); 2184 m_adj(m, -todrop); 2185 tlen -= todrop; 2186 tiflags &= ~(TH_PUSH|TH_FIN); 2187 } 2188 2189 /* 2190 * If last ACK falls within this segment's sequence numbers, 2191 * record the timestamp. 2192 * NOTE: 2193 * 1) That the test incorporates suggestions from the latest 2194 * proposal of the tcplw (at) cray.com list (Braden 1993/04/26). 2195 * 2) That updating only on newer timestamps interferes with 2196 * our earlier PAWS tests, so this check should be solely 2197 * predicated on the sequence space of this segment. 2198 * 3) That we modify the segment boundary check to be 2199 * Last.ACK.Sent <= SEG.SEQ + SEG.Len 2200 * instead of RFC1323's 2201 * Last.ACK.Sent < SEG.SEQ + SEG.Len, 2202 * This modified check allows us to overcome RFC1323's 2203 * limitations as described in Stevens TCP/IP Illustrated 2204 * Vol. 2 p.869. In such cases, we can still calculate the 2205 * RTT correctly when RCV.NXT == Last.ACK.Sent. 2206 */ 2207 if (opti.ts_present && 2208 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 2209 SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen + 2210 ((tiflags & (TH_SYN|TH_FIN)) != 0))) { 2211 tp->ts_recent_age = tcp_now; 2212 tp->ts_recent = opti.ts_val; 2213 } 2214 2215 /* 2216 * If the RST bit is set examine the state: 2217 * SYN_RECEIVED STATE: 2218 * If passive open, return to LISTEN state. 2219 * If active open, inform user that connection was refused. 2220 * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES: 2221 * Inform user that connection was reset, and close tcb. 2222 * CLOSING, LAST_ACK, TIME_WAIT STATES 2223 * Close the tcb. 2224 */ 2225 if (tiflags & TH_RST) { 2226 if (th->th_seq != tp->last_ack_sent) 2227 goto dropafterack_ratelim; 2228 2229 switch (tp->t_state) { 2230 case TCPS_SYN_RECEIVED: 2231 so->so_error = ECONNREFUSED; 2232 goto close; 2233 2234 case TCPS_ESTABLISHED: 2235 case TCPS_FIN_WAIT_1: 2236 case TCPS_FIN_WAIT_2: 2237 case TCPS_CLOSE_WAIT: 2238 so->so_error = ECONNRESET; 2239 close: 2240 tp->t_state = TCPS_CLOSED; 2241 TCP_STATINC(TCP_STAT_DROPS); 2242 tp = tcp_close(tp); 2243 goto drop; 2244 2245 case TCPS_CLOSING: 2246 case TCPS_LAST_ACK: 2247 case TCPS_TIME_WAIT: 2248 tp = tcp_close(tp); 2249 goto drop; 2250 } 2251 } 2252 2253 /* 2254 * Since we've covered the SYN-SENT and SYN-RECEIVED states above 2255 * we must be in a synchronized state. RFC791 states (under RST 2256 * generation) that any unacceptable segment (an out-of-order SYN 2257 * qualifies) received in a synchronized state must elicit only an 2258 * empty acknowledgment segment ... and the connection remains in 2259 * the same state. 2260 */ 2261 if (tiflags & TH_SYN) { 2262 if (tp->rcv_nxt == th->th_seq) { 2263 tcp_respond(tp, m, m, th, (tcp_seq)0, th->th_ack - 1, 2264 TH_ACK); 2265 if (tcp_saveti) 2266 m_freem(tcp_saveti); 2267 return; 2268 } 2269 2270 goto dropafterack_ratelim; 2271 } 2272 2273 /* 2274 * If the ACK bit is off we drop the segment and return. 2275 */ 2276 if ((tiflags & TH_ACK) == 0) { 2277 if (tp->t_flags & TF_ACKNOW) 2278 goto dropafterack; 2279 else 2280 goto drop; 2281 } 2282 2283 /* 2284 * Ack processing. 2285 */ 2286 switch (tp->t_state) { 2287 2288 /* 2289 * In SYN_RECEIVED state if the ack ACKs our SYN then enter 2290 * ESTABLISHED state and continue processing, otherwise 2291 * send an RST. 2292 */ 2293 case TCPS_SYN_RECEIVED: 2294 if (SEQ_GT(tp->snd_una, th->th_ack) || 2295 SEQ_GT(th->th_ack, tp->snd_max)) 2296 goto dropwithreset; 2297 TCP_STATINC(TCP_STAT_CONNECTS); 2298 soisconnected(so); 2299 tcp_established(tp); 2300 /* Do window scaling? */ 2301 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2302 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2303 tp->snd_scale = tp->requested_s_scale; 2304 tp->rcv_scale = tp->request_r_scale; 2305 } 2306 TCP_REASS_LOCK(tp); 2307 (void) tcp_reass(tp, NULL, (struct mbuf *)0, &tlen); 2308 TCP_REASS_UNLOCK(tp); 2309 tp->snd_wl1 = th->th_seq - 1; 2310 /* fall into ... */ 2311 2312 /* 2313 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 2314 * ACKs. If the ack is in the range 2315 * tp->snd_una < th->th_ack <= tp->snd_max 2316 * then advance tp->snd_una to th->th_ack and drop 2317 * data from the retransmission queue. If this ACK reflects 2318 * more up to date window information we update our window information. 2319 */ 2320 case TCPS_ESTABLISHED: 2321 case TCPS_FIN_WAIT_1: 2322 case TCPS_FIN_WAIT_2: 2323 case TCPS_CLOSE_WAIT: 2324 case TCPS_CLOSING: 2325 case TCPS_LAST_ACK: 2326 case TCPS_TIME_WAIT: 2327 2328 if (SEQ_LEQ(th->th_ack, tp->snd_una)) { 2329 if (tlen == 0 && !dupseg && tiwin == tp->snd_wnd) { 2330 TCP_STATINC(TCP_STAT_RCVDUPPACK); 2331 /* 2332 * If we have outstanding data (other than 2333 * a window probe), this is a completely 2334 * duplicate ack (ie, window info didn't 2335 * change), the ack is the biggest we've 2336 * seen and we've seen exactly our rexmt 2337 * threshhold of them, assume a packet 2338 * has been dropped and retransmit it. 2339 * Kludge snd_nxt & the congestion 2340 * window so we send only this one 2341 * packet. 2342 */ 2343 if (TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 || 2344 th->th_ack != tp->snd_una) 2345 tp->t_dupacks = 0; 2346 else if (tp->t_partialacks < 0 && 2347 (++tp->t_dupacks == tcprexmtthresh || 2348 TCP_FACK_FASTRECOV(tp))) { 2349 /* 2350 * Do the fast retransmit, and adjust 2351 * congestion control paramenters. 2352 */ 2353 if (tp->t_congctl->fast_retransmit(tp, th)) { 2354 /* False fast retransmit */ 2355 break; 2356 } else 2357 goto drop; 2358 } else if (tp->t_dupacks > tcprexmtthresh) { 2359 tp->snd_cwnd += tp->t_segsz; 2360 (void) tcp_output(tp); 2361 goto drop; 2362 } 2363 } else { 2364 /* 2365 * If the ack appears to be very old, only 2366 * allow data that is in-sequence. This 2367 * makes it somewhat more difficult to insert 2368 * forged data by guessing sequence numbers. 2369 * Sent an ack to try to update the send 2370 * sequence number on the other side. 2371 */ 2372 if (tlen && th->th_seq != tp->rcv_nxt && 2373 SEQ_LT(th->th_ack, 2374 tp->snd_una - tp->max_sndwnd)) 2375 goto dropafterack; 2376 } 2377 break; 2378 } 2379 /* 2380 * If the congestion window was inflated to account 2381 * for the other side's cached packets, retract it. 2382 */ 2383 /* XXX: make SACK have his own congestion control 2384 * struct -- rpaulo */ 2385 if (TCP_SACK_ENABLED(tp)) 2386 tcp_sack_newack(tp, th); 2387 else 2388 tp->t_congctl->fast_retransmit_newack(tp, th); 2389 if (SEQ_GT(th->th_ack, tp->snd_max)) { 2390 TCP_STATINC(TCP_STAT_RCVACKTOOMUCH); 2391 goto dropafterack; 2392 } 2393 acked = th->th_ack - tp->snd_una; 2394 tcps = TCP_STAT_GETREF(); 2395 tcps[TCP_STAT_RCVACKPACK]++; 2396 tcps[TCP_STAT_RCVACKBYTE] += acked; 2397 TCP_STAT_PUTREF(); 2398 2399 /* 2400 * If we have a timestamp reply, update smoothed 2401 * round trip time. If no timestamp is present but 2402 * transmit timer is running and timed sequence 2403 * number was acked, update smoothed round trip time. 2404 * Since we now have an rtt measurement, cancel the 2405 * timer backoff (cf., Phil Karn's retransmit alg.). 2406 * Recompute the initial retransmit timer. 2407 */ 2408 if (ts_rtt) 2409 tcp_xmit_timer(tp, ts_rtt); 2410 else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) 2411 tcp_xmit_timer(tp, tcp_now - tp->t_rtttime); 2412 2413 /* 2414 * If all outstanding data is acked, stop retransmit 2415 * timer and remember to restart (more output or persist). 2416 * If there is more data to be acked, restart retransmit 2417 * timer, using current (possibly backed-off) value. 2418 */ 2419 if (th->th_ack == tp->snd_max) { 2420 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2421 needoutput = 1; 2422 } else if (TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) 2423 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 2424 2425 /* 2426 * New data has been acked, adjust the congestion window. 2427 */ 2428 tp->t_congctl->newack(tp, th); 2429 2430 nd6_hint(tp); 2431 if (acked > so->so_snd.sb_cc) { 2432 tp->snd_wnd -= so->so_snd.sb_cc; 2433 sbdrop(&so->so_snd, (int)so->so_snd.sb_cc); 2434 ourfinisacked = 1; 2435 } else { 2436 if (acked > (tp->t_lastoff - tp->t_inoff)) 2437 tp->t_lastm = NULL; 2438 sbdrop(&so->so_snd, acked); 2439 tp->t_lastoff -= acked; 2440 tp->snd_wnd -= acked; 2441 ourfinisacked = 0; 2442 } 2443 sowwakeup(so); 2444 2445 icmp_check(tp, th, acked); 2446 2447 tp->snd_una = th->th_ack; 2448 if (SEQ_GT(tp->snd_una, tp->snd_fack)) 2449 tp->snd_fack = tp->snd_una; 2450 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2451 tp->snd_nxt = tp->snd_una; 2452 if (SEQ_LT(tp->snd_high, tp->snd_una)) 2453 tp->snd_high = tp->snd_una; 2454 2455 switch (tp->t_state) { 2456 2457 /* 2458 * In FIN_WAIT_1 STATE in addition to the processing 2459 * for the ESTABLISHED state if our FIN is now acknowledged 2460 * then enter FIN_WAIT_2. 2461 */ 2462 case TCPS_FIN_WAIT_1: 2463 if (ourfinisacked) { 2464 /* 2465 * If we can't receive any more 2466 * data, then closing user can proceed. 2467 * Starting the timer is contrary to the 2468 * specification, but if we don't get a FIN 2469 * we'll hang forever. 2470 */ 2471 if (so->so_state & SS_CANTRCVMORE) { 2472 soisdisconnected(so); 2473 if (tp->t_maxidle > 0) 2474 TCP_TIMER_ARM(tp, TCPT_2MSL, 2475 tp->t_maxidle); 2476 } 2477 tp->t_state = TCPS_FIN_WAIT_2; 2478 } 2479 break; 2480 2481 /* 2482 * In CLOSING STATE in addition to the processing for 2483 * the ESTABLISHED state if the ACK acknowledges our FIN 2484 * then enter the TIME-WAIT state, otherwise ignore 2485 * the segment. 2486 */ 2487 case TCPS_CLOSING: 2488 if (ourfinisacked) { 2489 tp->t_state = TCPS_TIME_WAIT; 2490 tcp_canceltimers(tp); 2491 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 2492 soisdisconnected(so); 2493 } 2494 break; 2495 2496 /* 2497 * In LAST_ACK, we may still be waiting for data to drain 2498 * and/or to be acked, as well as for the ack of our FIN. 2499 * If our FIN is now acknowledged, delete the TCB, 2500 * enter the closed state and return. 2501 */ 2502 case TCPS_LAST_ACK: 2503 if (ourfinisacked) { 2504 tp = tcp_close(tp); 2505 goto drop; 2506 } 2507 break; 2508 2509 /* 2510 * In TIME_WAIT state the only thing that should arrive 2511 * is a retransmission of the remote FIN. Acknowledge 2512 * it and restart the finack timer. 2513 */ 2514 case TCPS_TIME_WAIT: 2515 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 2516 goto dropafterack; 2517 } 2518 } 2519 2520 step6: 2521 /* 2522 * Update window information. 2523 * Don't look at window if no ACK: TAC's send garbage on first SYN. 2524 */ 2525 if ((tiflags & TH_ACK) && (SEQ_LT(tp->snd_wl1, th->th_seq) || 2526 (tp->snd_wl1 == th->th_seq && (SEQ_LT(tp->snd_wl2, th->th_ack) || 2527 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))) { 2528 /* keep track of pure window updates */ 2529 if (tlen == 0 && 2530 tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) 2531 TCP_STATINC(TCP_STAT_RCVWINUPD); 2532 tp->snd_wnd = tiwin; 2533 tp->snd_wl1 = th->th_seq; 2534 tp->snd_wl2 = th->th_ack; 2535 if (tp->snd_wnd > tp->max_sndwnd) 2536 tp->max_sndwnd = tp->snd_wnd; 2537 needoutput = 1; 2538 } 2539 2540 /* 2541 * Process segments with URG. 2542 */ 2543 if ((tiflags & TH_URG) && th->th_urp && 2544 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2545 /* 2546 * This is a kludge, but if we receive and accept 2547 * random urgent pointers, we'll crash in 2548 * soreceive. It's hard to imagine someone 2549 * actually wanting to send this much urgent data. 2550 */ 2551 if (th->th_urp + so->so_rcv.sb_cc > sb_max) { 2552 th->th_urp = 0; /* XXX */ 2553 tiflags &= ~TH_URG; /* XXX */ 2554 goto dodata; /* XXX */ 2555 } 2556 /* 2557 * If this segment advances the known urgent pointer, 2558 * then mark the data stream. This should not happen 2559 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 2560 * a FIN has been received from the remote side. 2561 * In these states we ignore the URG. 2562 * 2563 * According to RFC961 (Assigned Protocols), 2564 * the urgent pointer points to the last octet 2565 * of urgent data. We continue, however, 2566 * to consider it to indicate the first octet 2567 * of data past the urgent section as the original 2568 * spec states (in one of two places). 2569 */ 2570 if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) { 2571 tp->rcv_up = th->th_seq + th->th_urp; 2572 so->so_oobmark = so->so_rcv.sb_cc + 2573 (tp->rcv_up - tp->rcv_nxt) - 1; 2574 if (so->so_oobmark == 0) 2575 so->so_state |= SS_RCVATMARK; 2576 sohasoutofband(so); 2577 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); 2578 } 2579 /* 2580 * Remove out of band data so doesn't get presented to user. 2581 * This can happen independent of advancing the URG pointer, 2582 * but if two URG's are pending at once, some out-of-band 2583 * data may creep in... ick. 2584 */ 2585 if (th->th_urp <= (u_int16_t) tlen 2586 #ifdef SO_OOBINLINE 2587 && (so->so_options & SO_OOBINLINE) == 0 2588 #endif 2589 ) 2590 tcp_pulloutofband(so, th, m, hdroptlen); 2591 } else 2592 /* 2593 * If no out of band data is expected, 2594 * pull receive urgent pointer along 2595 * with the receive window. 2596 */ 2597 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) 2598 tp->rcv_up = tp->rcv_nxt; 2599 dodata: /* XXX */ 2600 2601 /* 2602 * Process the segment text, merging it into the TCP sequencing queue, 2603 * and arranging for acknowledgement of receipt if necessary. 2604 * This process logically involves adjusting tp->rcv_wnd as data 2605 * is presented to the user (this happens in tcp_usrreq.c, 2606 * case PRU_RCVD). If a FIN has already been received on this 2607 * connection then we just ignore the text. 2608 */ 2609 if ((tlen || (tiflags & TH_FIN)) && 2610 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2611 /* 2612 * Insert segment ti into reassembly queue of tcp with 2613 * control block tp. Return TH_FIN if reassembly now includes 2614 * a segment with FIN. The macro form does the common case 2615 * inline (segment is the next to be received on an 2616 * established connection, and the queue is empty), 2617 * avoiding linkage into and removal from the queue and 2618 * repetition of various conversions. 2619 * Set DELACK for segments received in order, but ack 2620 * immediately when segments are out of order 2621 * (so fast retransmit can work). 2622 */ 2623 /* NOTE: this was TCP_REASS() macro, but used only once */ 2624 TCP_REASS_LOCK(tp); 2625 if (th->th_seq == tp->rcv_nxt && 2626 TAILQ_FIRST(&tp->segq) == NULL && 2627 tp->t_state == TCPS_ESTABLISHED) { 2628 tcp_setup_ack(tp, th); 2629 tp->rcv_nxt += tlen; 2630 tiflags = th->th_flags & TH_FIN; 2631 tcps = TCP_STAT_GETREF(); 2632 tcps[TCP_STAT_RCVPACK]++; 2633 tcps[TCP_STAT_RCVBYTE] += tlen; 2634 TCP_STAT_PUTREF(); 2635 nd6_hint(tp); 2636 if (so->so_state & SS_CANTRCVMORE) 2637 m_freem(m); 2638 else { 2639 m_adj(m, hdroptlen); 2640 sbappendstream(&(so)->so_rcv, m); 2641 } 2642 TCP_REASS_UNLOCK(tp); 2643 sorwakeup(so); 2644 } else { 2645 m_adj(m, hdroptlen); 2646 tiflags = tcp_reass(tp, th, m, &tlen); 2647 tp->t_flags |= TF_ACKNOW; 2648 TCP_REASS_UNLOCK(tp); 2649 } 2650 2651 /* 2652 * Note the amount of data that peer has sent into 2653 * our window, in order to estimate the sender's 2654 * buffer size. 2655 */ 2656 len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); 2657 } else { 2658 m_freem(m); 2659 m = NULL; 2660 tiflags &= ~TH_FIN; 2661 } 2662 2663 /* 2664 * If FIN is received ACK the FIN and let the user know 2665 * that the connection is closing. Ignore a FIN received before 2666 * the connection is fully established. 2667 */ 2668 if ((tiflags & TH_FIN) && TCPS_HAVEESTABLISHED(tp->t_state)) { 2669 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2670 socantrcvmore(so); 2671 tp->t_flags |= TF_ACKNOW; 2672 tp->rcv_nxt++; 2673 } 2674 switch (tp->t_state) { 2675 2676 /* 2677 * In ESTABLISHED STATE enter the CLOSE_WAIT state. 2678 */ 2679 case TCPS_ESTABLISHED: 2680 tp->t_state = TCPS_CLOSE_WAIT; 2681 break; 2682 2683 /* 2684 * If still in FIN_WAIT_1 STATE FIN has not been acked so 2685 * enter the CLOSING state. 2686 */ 2687 case TCPS_FIN_WAIT_1: 2688 tp->t_state = TCPS_CLOSING; 2689 break; 2690 2691 /* 2692 * In FIN_WAIT_2 state enter the TIME_WAIT state, 2693 * starting the time-wait timer, turning off the other 2694 * standard timers. 2695 */ 2696 case TCPS_FIN_WAIT_2: 2697 tp->t_state = TCPS_TIME_WAIT; 2698 tcp_canceltimers(tp); 2699 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 2700 soisdisconnected(so); 2701 break; 2702 2703 /* 2704 * In TIME_WAIT state restart the 2 MSL time_wait timer. 2705 */ 2706 case TCPS_TIME_WAIT: 2707 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 2708 break; 2709 } 2710 } 2711 #ifdef TCP_DEBUG 2712 if (so->so_options & SO_DEBUG) 2713 tcp_trace(TA_INPUT, ostate, tp, tcp_saveti, 0); 2714 #endif 2715 2716 /* 2717 * Return any desired output. 2718 */ 2719 if (needoutput || (tp->t_flags & TF_ACKNOW)) { 2720 (void) tcp_output(tp); 2721 } 2722 if (tcp_saveti) 2723 m_freem(tcp_saveti); 2724 return; 2725 2726 badsyn: 2727 /* 2728 * Received a bad SYN. Increment counters and dropwithreset. 2729 */ 2730 TCP_STATINC(TCP_STAT_BADSYN); 2731 tp = NULL; 2732 goto dropwithreset; 2733 2734 dropafterack: 2735 /* 2736 * Generate an ACK dropping incoming segment if it occupies 2737 * sequence space, where the ACK reflects our state. 2738 */ 2739 if (tiflags & TH_RST) 2740 goto drop; 2741 goto dropafterack2; 2742 2743 dropafterack_ratelim: 2744 /* 2745 * We may want to rate-limit ACKs against SYN/RST attack. 2746 */ 2747 if (ppsratecheck(&tcp_ackdrop_ppslim_last, &tcp_ackdrop_ppslim_count, 2748 tcp_ackdrop_ppslim) == 0) { 2749 /* XXX stat */ 2750 goto drop; 2751 } 2752 /* ...fall into dropafterack2... */ 2753 2754 dropafterack2: 2755 m_freem(m); 2756 tp->t_flags |= TF_ACKNOW; 2757 (void) tcp_output(tp); 2758 if (tcp_saveti) 2759 m_freem(tcp_saveti); 2760 return; 2761 2762 dropwithreset_ratelim: 2763 /* 2764 * We may want to rate-limit RSTs in certain situations, 2765 * particularly if we are sending an RST in response to 2766 * an attempt to connect to or otherwise communicate with 2767 * a port for which we have no socket. 2768 */ 2769 if (ppsratecheck(&tcp_rst_ppslim_last, &tcp_rst_ppslim_count, 2770 tcp_rst_ppslim) == 0) { 2771 /* XXX stat */ 2772 goto drop; 2773 } 2774 /* ...fall into dropwithreset... */ 2775 2776 dropwithreset: 2777 /* 2778 * Generate a RST, dropping incoming segment. 2779 * Make ACK acceptable to originator of segment. 2780 */ 2781 if (tiflags & TH_RST) 2782 goto drop; 2783 2784 switch (af) { 2785 #ifdef INET6 2786 case AF_INET6: 2787 /* For following calls to tcp_respond */ 2788 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) 2789 goto drop; 2790 break; 2791 #endif /* INET6 */ 2792 case AF_INET: 2793 if (IN_MULTICAST(ip->ip_dst.s_addr) || 2794 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 2795 goto drop; 2796 } 2797 2798 if (tiflags & TH_ACK) 2799 (void)tcp_respond(tp, m, m, th, (tcp_seq)0, th->th_ack, TH_RST); 2800 else { 2801 if (tiflags & TH_SYN) 2802 tlen++; 2803 (void)tcp_respond(tp, m, m, th, th->th_seq + tlen, (tcp_seq)0, 2804 TH_RST|TH_ACK); 2805 } 2806 if (tcp_saveti) 2807 m_freem(tcp_saveti); 2808 return; 2809 2810 badcsum: 2811 drop: 2812 /* 2813 * Drop space held by incoming segment and return. 2814 */ 2815 if (tp) { 2816 if (tp->t_inpcb) 2817 so = tp->t_inpcb->inp_socket; 2818 #ifdef INET6 2819 else if (tp->t_in6pcb) 2820 so = tp->t_in6pcb->in6p_socket; 2821 #endif 2822 else 2823 so = NULL; 2824 #ifdef TCP_DEBUG 2825 if (so && (so->so_options & SO_DEBUG) != 0) 2826 tcp_trace(TA_DROP, ostate, tp, tcp_saveti, 0); 2827 #endif 2828 } 2829 if (tcp_saveti) 2830 m_freem(tcp_saveti); 2831 m_freem(m); 2832 return; 2833 } 2834 2835 #ifdef TCP_SIGNATURE 2836 int 2837 tcp_signature_apply(void *fstate, void *data, u_int len) 2838 { 2839 2840 MD5Update(fstate, (u_char *)data, len); 2841 return (0); 2842 } 2843 2844 struct secasvar * 2845 tcp_signature_getsav(struct mbuf *m, struct tcphdr *th) 2846 { 2847 struct secasvar *sav; 2848 #ifdef FAST_IPSEC 2849 union sockaddr_union dst; 2850 #endif 2851 struct ip *ip; 2852 struct ip6_hdr *ip6; 2853 2854 ip = mtod(m, struct ip *); 2855 switch (ip->ip_v) { 2856 case 4: 2857 ip = mtod(m, struct ip *); 2858 ip6 = NULL; 2859 break; 2860 case 6: 2861 ip = NULL; 2862 ip6 = mtod(m, struct ip6_hdr *); 2863 break; 2864 default: 2865 return (NULL); 2866 } 2867 2868 #ifdef FAST_IPSEC 2869 /* Extract the destination from the IP header in the mbuf. */ 2870 bzero(&dst, sizeof(union sockaddr_union)); 2871 if (ip !=NULL) { 2872 dst.sa.sa_len = sizeof(struct sockaddr_in); 2873 dst.sa.sa_family = AF_INET; 2874 dst.sin.sin_addr = ip->ip_dst; 2875 } else { 2876 dst.sa.sa_len = sizeof(struct sockaddr_in6); 2877 dst.sa.sa_family = AF_INET6; 2878 dst.sin6.sin6_addr = ip6->ip6_dst; 2879 } 2880 2881 /* 2882 * Look up an SADB entry which matches the address of the peer. 2883 */ 2884 sav = KEY_ALLOCSA(&dst, IPPROTO_TCP, htonl(TCP_SIG_SPI)); 2885 #else 2886 if (ip) 2887 sav = key_allocsa(AF_INET, (void *)&ip->ip_src, 2888 (void *)&ip->ip_dst, IPPROTO_TCP, 2889 htonl(TCP_SIG_SPI), 0, 0); 2890 else 2891 sav = key_allocsa(AF_INET6, (void *)&ip6->ip6_src, 2892 (void *)&ip6->ip6_dst, IPPROTO_TCP, 2893 htonl(TCP_SIG_SPI), 0, 0); 2894 #endif 2895 2896 return (sav); /* freesav must be performed by caller */ 2897 } 2898 2899 int 2900 tcp_signature(struct mbuf *m, struct tcphdr *th, int thoff, 2901 struct secasvar *sav, char *sig) 2902 { 2903 MD5_CTX ctx; 2904 struct ip *ip; 2905 struct ipovly *ipovly; 2906 struct ip6_hdr *ip6; 2907 struct ippseudo ippseudo; 2908 struct ip6_hdr_pseudo ip6pseudo; 2909 struct tcphdr th0; 2910 int l, tcphdrlen; 2911 2912 if (sav == NULL) 2913 return (-1); 2914 2915 tcphdrlen = th->th_off * 4; 2916 2917 switch (mtod(m, struct ip *)->ip_v) { 2918 case 4: 2919 ip = mtod(m, struct ip *); 2920 ip6 = NULL; 2921 break; 2922 case 6: 2923 ip = NULL; 2924 ip6 = mtod(m, struct ip6_hdr *); 2925 break; 2926 default: 2927 return (-1); 2928 } 2929 2930 MD5Init(&ctx); 2931 2932 if (ip) { 2933 memset(&ippseudo, 0, sizeof(ippseudo)); 2934 ipovly = (struct ipovly *)ip; 2935 ippseudo.ippseudo_src = ipovly->ih_src; 2936 ippseudo.ippseudo_dst = ipovly->ih_dst; 2937 ippseudo.ippseudo_pad = 0; 2938 ippseudo.ippseudo_p = IPPROTO_TCP; 2939 ippseudo.ippseudo_len = htons(m->m_pkthdr.len - thoff); 2940 MD5Update(&ctx, (char *)&ippseudo, sizeof(ippseudo)); 2941 } else { 2942 memset(&ip6pseudo, 0, sizeof(ip6pseudo)); 2943 ip6pseudo.ip6ph_src = ip6->ip6_src; 2944 in6_clearscope(&ip6pseudo.ip6ph_src); 2945 ip6pseudo.ip6ph_dst = ip6->ip6_dst; 2946 in6_clearscope(&ip6pseudo.ip6ph_dst); 2947 ip6pseudo.ip6ph_len = htons(m->m_pkthdr.len - thoff); 2948 ip6pseudo.ip6ph_nxt = IPPROTO_TCP; 2949 MD5Update(&ctx, (char *)&ip6pseudo, sizeof(ip6pseudo)); 2950 } 2951 2952 th0 = *th; 2953 th0.th_sum = 0; 2954 MD5Update(&ctx, (char *)&th0, sizeof(th0)); 2955 2956 l = m->m_pkthdr.len - thoff - tcphdrlen; 2957 if (l > 0) 2958 m_apply(m, thoff + tcphdrlen, 2959 m->m_pkthdr.len - thoff - tcphdrlen, 2960 tcp_signature_apply, &ctx); 2961 2962 MD5Update(&ctx, _KEYBUF(sav->key_auth), _KEYLEN(sav->key_auth)); 2963 MD5Final(sig, &ctx); 2964 2965 return (0); 2966 } 2967 #endif 2968 2969 static int 2970 tcp_dooptions(struct tcpcb *tp, const u_char *cp, int cnt, 2971 struct tcphdr *th, 2972 struct mbuf *m, int toff, struct tcp_opt_info *oi) 2973 { 2974 u_int16_t mss; 2975 int opt, optlen = 0; 2976 #ifdef TCP_SIGNATURE 2977 void *sigp = NULL; 2978 char sigbuf[TCP_SIGLEN]; 2979 struct secasvar *sav = NULL; 2980 #endif 2981 2982 for (; cp && cnt > 0; cnt -= optlen, cp += optlen) { 2983 opt = cp[0]; 2984 if (opt == TCPOPT_EOL) 2985 break; 2986 if (opt == TCPOPT_NOP) 2987 optlen = 1; 2988 else { 2989 if (cnt < 2) 2990 break; 2991 optlen = cp[1]; 2992 if (optlen < 2 || optlen > cnt) 2993 break; 2994 } 2995 switch (opt) { 2996 2997 default: 2998 continue; 2999 3000 case TCPOPT_MAXSEG: 3001 if (optlen != TCPOLEN_MAXSEG) 3002 continue; 3003 if (!(th->th_flags & TH_SYN)) 3004 continue; 3005 if (TCPS_HAVERCVDSYN(tp->t_state)) 3006 continue; 3007 bcopy(cp + 2, &mss, sizeof(mss)); 3008 oi->maxseg = ntohs(mss); 3009 break; 3010 3011 case TCPOPT_WINDOW: 3012 if (optlen != TCPOLEN_WINDOW) 3013 continue; 3014 if (!(th->th_flags & TH_SYN)) 3015 continue; 3016 if (TCPS_HAVERCVDSYN(tp->t_state)) 3017 continue; 3018 tp->t_flags |= TF_RCVD_SCALE; 3019 tp->requested_s_scale = cp[2]; 3020 if (tp->requested_s_scale > TCP_MAX_WINSHIFT) { 3021 #if 0 /*XXX*/ 3022 char *p; 3023 3024 if (ip) 3025 p = ntohl(ip->ip_src); 3026 #ifdef INET6 3027 else if (ip6) 3028 p = ip6_sprintf(&ip6->ip6_src); 3029 #endif 3030 else 3031 p = "(unknown)"; 3032 log(LOG_ERR, "TCP: invalid wscale %d from %s, " 3033 "assuming %d\n", 3034 tp->requested_s_scale, p, 3035 TCP_MAX_WINSHIFT); 3036 #else 3037 log(LOG_ERR, "TCP: invalid wscale %d, " 3038 "assuming %d\n", 3039 tp->requested_s_scale, 3040 TCP_MAX_WINSHIFT); 3041 #endif 3042 tp->requested_s_scale = TCP_MAX_WINSHIFT; 3043 } 3044 break; 3045 3046 case TCPOPT_TIMESTAMP: 3047 if (optlen != TCPOLEN_TIMESTAMP) 3048 continue; 3049 oi->ts_present = 1; 3050 bcopy(cp + 2, &oi->ts_val, sizeof(oi->ts_val)); 3051 NTOHL(oi->ts_val); 3052 bcopy(cp + 6, &oi->ts_ecr, sizeof(oi->ts_ecr)); 3053 NTOHL(oi->ts_ecr); 3054 3055 if (!(th->th_flags & TH_SYN)) 3056 continue; 3057 if (TCPS_HAVERCVDSYN(tp->t_state)) 3058 continue; 3059 /* 3060 * A timestamp received in a SYN makes 3061 * it ok to send timestamp requests and replies. 3062 */ 3063 tp->t_flags |= TF_RCVD_TSTMP; 3064 tp->ts_recent = oi->ts_val; 3065 tp->ts_recent_age = tcp_now; 3066 break; 3067 3068 case TCPOPT_SACK_PERMITTED: 3069 if (optlen != TCPOLEN_SACK_PERMITTED) 3070 continue; 3071 if (!(th->th_flags & TH_SYN)) 3072 continue; 3073 if (TCPS_HAVERCVDSYN(tp->t_state)) 3074 continue; 3075 if (tcp_do_sack) { 3076 tp->t_flags |= TF_SACK_PERMIT; 3077 tp->t_flags |= TF_WILL_SACK; 3078 } 3079 break; 3080 3081 case TCPOPT_SACK: 3082 tcp_sack_option(tp, th, cp, optlen); 3083 break; 3084 #ifdef TCP_SIGNATURE 3085 case TCPOPT_SIGNATURE: 3086 if (optlen != TCPOLEN_SIGNATURE) 3087 continue; 3088 if (sigp && bcmp(sigp, cp + 2, TCP_SIGLEN)) 3089 return (-1); 3090 3091 sigp = sigbuf; 3092 memcpy(sigbuf, cp + 2, TCP_SIGLEN); 3093 tp->t_flags |= TF_SIGNATURE; 3094 break; 3095 #endif 3096 } 3097 } 3098 3099 #ifdef TCP_SIGNATURE 3100 if (tp->t_flags & TF_SIGNATURE) { 3101 3102 sav = tcp_signature_getsav(m, th); 3103 3104 if (sav == NULL && tp->t_state == TCPS_LISTEN) 3105 return (-1); 3106 } 3107 3108 if ((sigp ? TF_SIGNATURE : 0) ^ (tp->t_flags & TF_SIGNATURE)) { 3109 if (sav == NULL) 3110 return (-1); 3111 #ifdef FAST_IPSEC 3112 KEY_FREESAV(&sav); 3113 #else 3114 key_freesav(sav); 3115 #endif 3116 return (-1); 3117 } 3118 3119 if (sigp) { 3120 char sig[TCP_SIGLEN]; 3121 3122 tcp_fields_to_net(th); 3123 if (tcp_signature(m, th, toff, sav, sig) < 0) { 3124 tcp_fields_to_host(th); 3125 if (sav == NULL) 3126 return (-1); 3127 #ifdef FAST_IPSEC 3128 KEY_FREESAV(&sav); 3129 #else 3130 key_freesav(sav); 3131 #endif 3132 return (-1); 3133 } 3134 tcp_fields_to_host(th); 3135 3136 if (bcmp(sig, sigp, TCP_SIGLEN)) { 3137 TCP_STATINC(TCP_STAT_BADSIG); 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 } else 3147 TCP_STATINC(TCP_STAT_GOODSIG); 3148 3149 key_sa_recordxfer(sav, m); 3150 #ifdef FAST_IPSEC 3151 KEY_FREESAV(&sav); 3152 #else 3153 key_freesav(sav); 3154 #endif 3155 } 3156 #endif 3157 3158 return (0); 3159 } 3160 3161 /* 3162 * Pull out of band byte out of a segment so 3163 * it doesn't appear in the user's data queue. 3164 * It is still reflected in the segment length for 3165 * sequencing purposes. 3166 */ 3167 void 3168 tcp_pulloutofband(struct socket *so, struct tcphdr *th, 3169 struct mbuf *m, int off) 3170 { 3171 int cnt = off + th->th_urp - 1; 3172 3173 while (cnt >= 0) { 3174 if (m->m_len > cnt) { 3175 char *cp = mtod(m, char *) + cnt; 3176 struct tcpcb *tp = sototcpcb(so); 3177 3178 tp->t_iobc = *cp; 3179 tp->t_oobflags |= TCPOOB_HAVEDATA; 3180 bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); 3181 m->m_len--; 3182 return; 3183 } 3184 cnt -= m->m_len; 3185 m = m->m_next; 3186 if (m == 0) 3187 break; 3188 } 3189 panic("tcp_pulloutofband"); 3190 } 3191 3192 /* 3193 * Collect new round-trip time estimate 3194 * and update averages and current timeout. 3195 */ 3196 void 3197 tcp_xmit_timer(struct tcpcb *tp, uint32_t rtt) 3198 { 3199 int32_t delta; 3200 3201 TCP_STATINC(TCP_STAT_RTTUPDATED); 3202 if (tp->t_srtt != 0) { 3203 /* 3204 * srtt is stored as fixed point with 3 bits after the 3205 * binary point (i.e., scaled by 8). The following magic 3206 * is equivalent to the smoothing algorithm in rfc793 with 3207 * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed 3208 * point). Adjust rtt to origin 0. 3209 */ 3210 delta = (rtt << 2) - (tp->t_srtt >> TCP_RTT_SHIFT); 3211 if ((tp->t_srtt += delta) <= 0) 3212 tp->t_srtt = 1 << 2; 3213 /* 3214 * We accumulate a smoothed rtt variance (actually, a 3215 * smoothed mean difference), then set the retransmit 3216 * timer to smoothed rtt + 4 times the smoothed variance. 3217 * rttvar is stored as fixed point with 2 bits after the 3218 * binary point (scaled by 4). The following is 3219 * equivalent to rfc793 smoothing with an alpha of .75 3220 * (rttvar = rttvar*3/4 + |delta| / 4). This replaces 3221 * rfc793's wired-in beta. 3222 */ 3223 if (delta < 0) 3224 delta = -delta; 3225 delta -= (tp->t_rttvar >> TCP_RTTVAR_SHIFT); 3226 if ((tp->t_rttvar += delta) <= 0) 3227 tp->t_rttvar = 1 << 2; 3228 } else { 3229 /* 3230 * No rtt measurement yet - use the unsmoothed rtt. 3231 * Set the variance to half the rtt (so our first 3232 * retransmit happens at 3*rtt). 3233 */ 3234 tp->t_srtt = rtt << (TCP_RTT_SHIFT + 2); 3235 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT + 2 - 1); 3236 } 3237 tp->t_rtttime = 0; 3238 tp->t_rxtshift = 0; 3239 3240 /* 3241 * the retransmit should happen at rtt + 4 * rttvar. 3242 * Because of the way we do the smoothing, srtt and rttvar 3243 * will each average +1/2 tick of bias. When we compute 3244 * the retransmit timer, we want 1/2 tick of rounding and 3245 * 1 extra tick because of +-1/2 tick uncertainty in the 3246 * firing of the timer. The bias will give us exactly the 3247 * 1.5 tick we need. But, because the bias is 3248 * statistical, we have to test that we don't drop below 3249 * the minimum feasible timer (which is 2 ticks). 3250 */ 3251 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), 3252 max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX); 3253 3254 /* 3255 * We received an ack for a packet that wasn't retransmitted; 3256 * it is probably safe to discard any error indications we've 3257 * received recently. This isn't quite right, but close enough 3258 * for now (a route might have failed after we sent a segment, 3259 * and the return path might not be symmetrical). 3260 */ 3261 tp->t_softerror = 0; 3262 } 3263 3264 3265 /* 3266 * TCP compressed state engine. Currently used to hold compressed 3267 * state for SYN_RECEIVED. 3268 */ 3269 3270 u_long syn_cache_count; 3271 u_int32_t syn_hash1, syn_hash2; 3272 3273 #define SYN_HASH(sa, sp, dp) \ 3274 ((((sa)->s_addr^syn_hash1)*(((((u_int32_t)(dp))<<16) + \ 3275 ((u_int32_t)(sp)))^syn_hash2))) 3276 #ifndef INET6 3277 #define SYN_HASHALL(hash, src, dst) \ 3278 do { \ 3279 hash = SYN_HASH(&((const struct sockaddr_in *)(src))->sin_addr, \ 3280 ((const struct sockaddr_in *)(src))->sin_port, \ 3281 ((const struct sockaddr_in *)(dst))->sin_port); \ 3282 } while (/*CONSTCOND*/ 0) 3283 #else 3284 #define SYN_HASH6(sa, sp, dp) \ 3285 ((((sa)->s6_addr32[0] ^ (sa)->s6_addr32[3] ^ syn_hash1) * \ 3286 (((((u_int32_t)(dp))<<16) + ((u_int32_t)(sp)))^syn_hash2)) \ 3287 & 0x7fffffff) 3288 3289 #define SYN_HASHALL(hash, src, dst) \ 3290 do { \ 3291 switch ((src)->sa_family) { \ 3292 case AF_INET: \ 3293 hash = SYN_HASH(&((const struct sockaddr_in *)(src))->sin_addr, \ 3294 ((const struct sockaddr_in *)(src))->sin_port, \ 3295 ((const struct sockaddr_in *)(dst))->sin_port); \ 3296 break; \ 3297 case AF_INET6: \ 3298 hash = SYN_HASH6(&((const struct sockaddr_in6 *)(src))->sin6_addr, \ 3299 ((const struct sockaddr_in6 *)(src))->sin6_port, \ 3300 ((const struct sockaddr_in6 *)(dst))->sin6_port); \ 3301 break; \ 3302 default: \ 3303 hash = 0; \ 3304 } \ 3305 } while (/*CONSTCOND*/0) 3306 #endif /* INET6 */ 3307 3308 POOL_INIT(syn_cache_pool, sizeof(struct syn_cache), 0, 0, 0, "synpl", NULL, 3309 IPL_SOFTNET); 3310 3311 /* 3312 * We don't estimate RTT with SYNs, so each packet starts with the default 3313 * RTT and each timer step has a fixed timeout value. 3314 */ 3315 #define SYN_CACHE_TIMER_ARM(sc) \ 3316 do { \ 3317 TCPT_RANGESET((sc)->sc_rxtcur, \ 3318 TCPTV_SRTTDFLT * tcp_backoff[(sc)->sc_rxtshift], TCPTV_MIN, \ 3319 TCPTV_REXMTMAX); \ 3320 callout_reset(&(sc)->sc_timer, \ 3321 (sc)->sc_rxtcur * (hz / PR_SLOWHZ), syn_cache_timer, (sc)); \ 3322 } while (/*CONSTCOND*/0) 3323 3324 #define SYN_CACHE_TIMESTAMP(sc) (tcp_now - (sc)->sc_timebase) 3325 3326 static inline void 3327 syn_cache_rm(struct syn_cache *sc) 3328 { 3329 TAILQ_REMOVE(&tcp_syn_cache[sc->sc_bucketidx].sch_bucket, 3330 sc, sc_bucketq); 3331 sc->sc_tp = NULL; 3332 LIST_REMOVE(sc, sc_tpq); 3333 tcp_syn_cache[sc->sc_bucketidx].sch_length--; 3334 callout_stop(&sc->sc_timer); 3335 syn_cache_count--; 3336 } 3337 3338 static inline void 3339 syn_cache_put(struct syn_cache *sc) 3340 { 3341 if (sc->sc_ipopts) 3342 (void) m_free(sc->sc_ipopts); 3343 rtcache_free(&sc->sc_route); 3344 if (callout_invoking(&sc->sc_timer)) 3345 sc->sc_flags |= SCF_DEAD; 3346 else { 3347 callout_destroy(&sc->sc_timer); 3348 pool_put(&syn_cache_pool, sc); 3349 } 3350 } 3351 3352 void 3353 syn_cache_init(void) 3354 { 3355 int i; 3356 3357 /* Initialize the hash buckets. */ 3358 for (i = 0; i < tcp_syn_cache_size; i++) 3359 TAILQ_INIT(&tcp_syn_cache[i].sch_bucket); 3360 } 3361 3362 void 3363 syn_cache_insert(struct syn_cache *sc, struct tcpcb *tp) 3364 { 3365 struct syn_cache_head *scp; 3366 struct syn_cache *sc2; 3367 int s; 3368 3369 /* 3370 * If there are no entries in the hash table, reinitialize 3371 * the hash secrets. 3372 */ 3373 if (syn_cache_count == 0) { 3374 syn_hash1 = arc4random(); 3375 syn_hash2 = arc4random(); 3376 } 3377 3378 SYN_HASHALL(sc->sc_hash, &sc->sc_src.sa, &sc->sc_dst.sa); 3379 sc->sc_bucketidx = sc->sc_hash % tcp_syn_cache_size; 3380 scp = &tcp_syn_cache[sc->sc_bucketidx]; 3381 3382 /* 3383 * Make sure that we don't overflow the per-bucket 3384 * limit or the total cache size limit. 3385 */ 3386 s = splsoftnet(); 3387 if (scp->sch_length >= tcp_syn_bucket_limit) { 3388 TCP_STATINC(TCP_STAT_SC_BUCKETOVERFLOW); 3389 /* 3390 * The bucket is full. Toss the oldest element in the 3391 * bucket. This will be the first entry in the bucket. 3392 */ 3393 sc2 = TAILQ_FIRST(&scp->sch_bucket); 3394 #ifdef DIAGNOSTIC 3395 /* 3396 * This should never happen; we should always find an 3397 * entry in our bucket. 3398 */ 3399 if (sc2 == NULL) 3400 panic("syn_cache_insert: bucketoverflow: impossible"); 3401 #endif 3402 syn_cache_rm(sc2); 3403 syn_cache_put(sc2); /* calls pool_put but see spl above */ 3404 } else if (syn_cache_count >= tcp_syn_cache_limit) { 3405 struct syn_cache_head *scp2, *sce; 3406 3407 TCP_STATINC(TCP_STAT_SC_OVERFLOWED); 3408 /* 3409 * The cache is full. Toss the oldest entry in the 3410 * first non-empty bucket we can find. 3411 * 3412 * XXX We would really like to toss the oldest 3413 * entry in the cache, but we hope that this 3414 * condition doesn't happen very often. 3415 */ 3416 scp2 = scp; 3417 if (TAILQ_EMPTY(&scp2->sch_bucket)) { 3418 sce = &tcp_syn_cache[tcp_syn_cache_size]; 3419 for (++scp2; scp2 != scp; scp2++) { 3420 if (scp2 >= sce) 3421 scp2 = &tcp_syn_cache[0]; 3422 if (! TAILQ_EMPTY(&scp2->sch_bucket)) 3423 break; 3424 } 3425 #ifdef DIAGNOSTIC 3426 /* 3427 * This should never happen; we should always find a 3428 * non-empty bucket. 3429 */ 3430 if (scp2 == scp) 3431 panic("syn_cache_insert: cacheoverflow: " 3432 "impossible"); 3433 #endif 3434 } 3435 sc2 = TAILQ_FIRST(&scp2->sch_bucket); 3436 syn_cache_rm(sc2); 3437 syn_cache_put(sc2); /* calls pool_put but see spl above */ 3438 } 3439 3440 /* 3441 * Initialize the entry's timer. 3442 */ 3443 sc->sc_rxttot = 0; 3444 sc->sc_rxtshift = 0; 3445 SYN_CACHE_TIMER_ARM(sc); 3446 3447 /* Link it from tcpcb entry */ 3448 LIST_INSERT_HEAD(&tp->t_sc, sc, sc_tpq); 3449 3450 /* Put it into the bucket. */ 3451 TAILQ_INSERT_TAIL(&scp->sch_bucket, sc, sc_bucketq); 3452 scp->sch_length++; 3453 syn_cache_count++; 3454 3455 TCP_STATINC(TCP_STAT_SC_ADDED); 3456 splx(s); 3457 } 3458 3459 /* 3460 * Walk the timer queues, looking for SYN,ACKs that need to be retransmitted. 3461 * If we have retransmitted an entry the maximum number of times, expire 3462 * that entry. 3463 */ 3464 void 3465 syn_cache_timer(void *arg) 3466 { 3467 struct syn_cache *sc = arg; 3468 3469 mutex_enter(softnet_lock); 3470 KERNEL_LOCK(1, NULL); 3471 callout_ack(&sc->sc_timer); 3472 3473 if (__predict_false(sc->sc_flags & SCF_DEAD)) { 3474 TCP_STATINC(TCP_STAT_SC_DELAYED_FREE); 3475 callout_destroy(&sc->sc_timer); 3476 pool_put(&syn_cache_pool, sc); 3477 KERNEL_UNLOCK_ONE(NULL); 3478 mutex_exit(softnet_lock); 3479 return; 3480 } 3481 3482 if (__predict_false(sc->sc_rxtshift == TCP_MAXRXTSHIFT)) { 3483 /* Drop it -- too many retransmissions. */ 3484 goto dropit; 3485 } 3486 3487 /* 3488 * Compute the total amount of time this entry has 3489 * been on a queue. If this entry has been on longer 3490 * than the keep alive timer would allow, expire it. 3491 */ 3492 sc->sc_rxttot += sc->sc_rxtcur; 3493 if (sc->sc_rxttot >= tcp_keepinit) 3494 goto dropit; 3495 3496 TCP_STATINC(TCP_STAT_SC_RETRANSMITTED); 3497 (void) syn_cache_respond(sc, NULL); 3498 3499 /* Advance the timer back-off. */ 3500 sc->sc_rxtshift++; 3501 SYN_CACHE_TIMER_ARM(sc); 3502 3503 KERNEL_UNLOCK_ONE(NULL); 3504 mutex_exit(softnet_lock); 3505 return; 3506 3507 dropit: 3508 TCP_STATINC(TCP_STAT_SC_TIMED_OUT); 3509 syn_cache_rm(sc); 3510 syn_cache_put(sc); /* calls pool_put but see spl above */ 3511 KERNEL_UNLOCK_ONE(NULL); 3512 mutex_exit(softnet_lock); 3513 } 3514 3515 /* 3516 * Remove syn cache created by the specified tcb entry, 3517 * because this does not make sense to keep them 3518 * (if there's no tcb entry, syn cache entry will never be used) 3519 */ 3520 void 3521 syn_cache_cleanup(struct tcpcb *tp) 3522 { 3523 struct syn_cache *sc, *nsc; 3524 int s; 3525 3526 s = splsoftnet(); 3527 3528 for (sc = LIST_FIRST(&tp->t_sc); sc != NULL; sc = nsc) { 3529 nsc = LIST_NEXT(sc, sc_tpq); 3530 3531 #ifdef DIAGNOSTIC 3532 if (sc->sc_tp != tp) 3533 panic("invalid sc_tp in syn_cache_cleanup"); 3534 #endif 3535 syn_cache_rm(sc); 3536 syn_cache_put(sc); /* calls pool_put but see spl above */ 3537 } 3538 /* just for safety */ 3539 LIST_INIT(&tp->t_sc); 3540 3541 splx(s); 3542 } 3543 3544 /* 3545 * Find an entry in the syn cache. 3546 */ 3547 struct syn_cache * 3548 syn_cache_lookup(const struct sockaddr *src, const struct sockaddr *dst, 3549 struct syn_cache_head **headp) 3550 { 3551 struct syn_cache *sc; 3552 struct syn_cache_head *scp; 3553 u_int32_t hash; 3554 int s; 3555 3556 SYN_HASHALL(hash, src, dst); 3557 3558 scp = &tcp_syn_cache[hash % tcp_syn_cache_size]; 3559 *headp = scp; 3560 s = splsoftnet(); 3561 for (sc = TAILQ_FIRST(&scp->sch_bucket); sc != NULL; 3562 sc = TAILQ_NEXT(sc, sc_bucketq)) { 3563 if (sc->sc_hash != hash) 3564 continue; 3565 if (!bcmp(&sc->sc_src, src, src->sa_len) && 3566 !bcmp(&sc->sc_dst, dst, dst->sa_len)) { 3567 splx(s); 3568 return (sc); 3569 } 3570 } 3571 splx(s); 3572 return (NULL); 3573 } 3574 3575 /* 3576 * This function gets called when we receive an ACK for a 3577 * socket in the LISTEN state. We look up the connection 3578 * in the syn cache, and if its there, we pull it out of 3579 * the cache and turn it into a full-blown connection in 3580 * the SYN-RECEIVED state. 3581 * 3582 * The return values may not be immediately obvious, and their effects 3583 * can be subtle, so here they are: 3584 * 3585 * NULL SYN was not found in cache; caller should drop the 3586 * packet and send an RST. 3587 * 3588 * -1 We were unable to create the new connection, and are 3589 * aborting it. An ACK,RST is being sent to the peer 3590 * (unless we got screwey sequence numbners; see below), 3591 * because the 3-way handshake has been completed. Caller 3592 * should not free the mbuf, since we may be using it. If 3593 * we are not, we will free it. 3594 * 3595 * Otherwise, the return value is a pointer to the new socket 3596 * associated with the connection. 3597 */ 3598 struct socket * 3599 syn_cache_get(struct sockaddr *src, struct sockaddr *dst, 3600 struct tcphdr *th, unsigned int hlen, unsigned int tlen, 3601 struct socket *so, struct mbuf *m) 3602 { 3603 struct syn_cache *sc; 3604 struct syn_cache_head *scp; 3605 struct inpcb *inp = NULL; 3606 #ifdef INET6 3607 struct in6pcb *in6p = NULL; 3608 #endif 3609 struct tcpcb *tp = 0; 3610 struct mbuf *am; 3611 int s; 3612 struct socket *oso; 3613 3614 s = splsoftnet(); 3615 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 3616 splx(s); 3617 return (NULL); 3618 } 3619 3620 /* 3621 * Verify the sequence and ack numbers. Try getting the correct 3622 * response again. 3623 */ 3624 if ((th->th_ack != sc->sc_iss + 1) || 3625 SEQ_LEQ(th->th_seq, sc->sc_irs) || 3626 SEQ_GT(th->th_seq, sc->sc_irs + 1 + sc->sc_win)) { 3627 (void) syn_cache_respond(sc, m); 3628 splx(s); 3629 return ((struct socket *)(-1)); 3630 } 3631 3632 /* Remove this cache entry */ 3633 syn_cache_rm(sc); 3634 splx(s); 3635 3636 /* 3637 * Ok, create the full blown connection, and set things up 3638 * as they would have been set up if we had created the 3639 * connection when the SYN arrived. If we can't create 3640 * the connection, abort it. 3641 */ 3642 /* 3643 * inp still has the OLD in_pcb stuff, set the 3644 * v6-related flags on the new guy, too. This is 3645 * done particularly for the case where an AF_INET6 3646 * socket is bound only to a port, and a v4 connection 3647 * comes in on that port. 3648 * we also copy the flowinfo from the original pcb 3649 * to the new one. 3650 */ 3651 oso = so; 3652 so = sonewconn(so, SS_ISCONNECTED); 3653 if (so == NULL) 3654 goto resetandabort; 3655 3656 switch (so->so_proto->pr_domain->dom_family) { 3657 #ifdef INET 3658 case AF_INET: 3659 inp = sotoinpcb(so); 3660 break; 3661 #endif 3662 #ifdef INET6 3663 case AF_INET6: 3664 in6p = sotoin6pcb(so); 3665 break; 3666 #endif 3667 } 3668 switch (src->sa_family) { 3669 #ifdef INET 3670 case AF_INET: 3671 if (inp) { 3672 inp->inp_laddr = ((struct sockaddr_in *)dst)->sin_addr; 3673 inp->inp_lport = ((struct sockaddr_in *)dst)->sin_port; 3674 inp->inp_options = ip_srcroute(); 3675 in_pcbstate(inp, INP_BOUND); 3676 if (inp->inp_options == NULL) { 3677 inp->inp_options = sc->sc_ipopts; 3678 sc->sc_ipopts = NULL; 3679 } 3680 } 3681 #ifdef INET6 3682 else if (in6p) { 3683 /* IPv4 packet to AF_INET6 socket */ 3684 bzero(&in6p->in6p_laddr, sizeof(in6p->in6p_laddr)); 3685 in6p->in6p_laddr.s6_addr16[5] = htons(0xffff); 3686 bcopy(&((struct sockaddr_in *)dst)->sin_addr, 3687 &in6p->in6p_laddr.s6_addr32[3], 3688 sizeof(((struct sockaddr_in *)dst)->sin_addr)); 3689 in6p->in6p_lport = ((struct sockaddr_in *)dst)->sin_port; 3690 in6totcpcb(in6p)->t_family = AF_INET; 3691 if (sotoin6pcb(oso)->in6p_flags & IN6P_IPV6_V6ONLY) 3692 in6p->in6p_flags |= IN6P_IPV6_V6ONLY; 3693 else 3694 in6p->in6p_flags &= ~IN6P_IPV6_V6ONLY; 3695 in6_pcbstate(in6p, IN6P_BOUND); 3696 } 3697 #endif 3698 break; 3699 #endif 3700 #ifdef INET6 3701 case AF_INET6: 3702 if (in6p) { 3703 in6p->in6p_laddr = ((struct sockaddr_in6 *)dst)->sin6_addr; 3704 in6p->in6p_lport = ((struct sockaddr_in6 *)dst)->sin6_port; 3705 in6_pcbstate(in6p, IN6P_BOUND); 3706 } 3707 break; 3708 #endif 3709 } 3710 #ifdef INET6 3711 if (in6p && in6totcpcb(in6p)->t_family == AF_INET6 && sotoinpcb(oso)) { 3712 struct in6pcb *oin6p = sotoin6pcb(oso); 3713 /* inherit socket options from the listening socket */ 3714 in6p->in6p_flags |= (oin6p->in6p_flags & IN6P_CONTROLOPTS); 3715 if (in6p->in6p_flags & IN6P_CONTROLOPTS) { 3716 m_freem(in6p->in6p_options); 3717 in6p->in6p_options = 0; 3718 } 3719 ip6_savecontrol(in6p, &in6p->in6p_options, 3720 mtod(m, struct ip6_hdr *), m); 3721 } 3722 #endif 3723 3724 #if defined(IPSEC) || defined(FAST_IPSEC) 3725 /* 3726 * we make a copy of policy, instead of sharing the policy, 3727 * for better behavior in terms of SA lookup and dead SA removal. 3728 */ 3729 if (inp) { 3730 /* copy old policy into new socket's */ 3731 if (ipsec_copy_pcbpolicy(sotoinpcb(oso)->inp_sp, inp->inp_sp)) 3732 printf("tcp_input: could not copy policy\n"); 3733 } 3734 #ifdef INET6 3735 else if (in6p) { 3736 /* copy old policy into new socket's */ 3737 if (ipsec_copy_pcbpolicy(sotoin6pcb(oso)->in6p_sp, 3738 in6p->in6p_sp)) 3739 printf("tcp_input: could not copy policy\n"); 3740 } 3741 #endif 3742 #endif 3743 3744 /* 3745 * Give the new socket our cached route reference. 3746 */ 3747 if (inp) { 3748 rtcache_copy(&inp->inp_route, &sc->sc_route); 3749 rtcache_free(&sc->sc_route); 3750 } 3751 #ifdef INET6 3752 else { 3753 rtcache_copy(&in6p->in6p_route, &sc->sc_route); 3754 rtcache_free(&sc->sc_route); 3755 } 3756 #endif 3757 3758 am = m_get(M_DONTWAIT, MT_SONAME); /* XXX */ 3759 if (am == NULL) 3760 goto resetandabort; 3761 MCLAIM(am, &tcp_mowner); 3762 am->m_len = src->sa_len; 3763 bcopy(src, mtod(am, void *), src->sa_len); 3764 if (inp) { 3765 if (in_pcbconnect(inp, am, &lwp0)) { 3766 (void) m_free(am); 3767 goto resetandabort; 3768 } 3769 } 3770 #ifdef INET6 3771 else if (in6p) { 3772 if (src->sa_family == AF_INET) { 3773 /* IPv4 packet to AF_INET6 socket */ 3774 struct sockaddr_in6 *sin6; 3775 sin6 = mtod(am, struct sockaddr_in6 *); 3776 am->m_len = sizeof(*sin6); 3777 bzero(sin6, sizeof(*sin6)); 3778 sin6->sin6_family = AF_INET6; 3779 sin6->sin6_len = sizeof(*sin6); 3780 sin6->sin6_port = ((struct sockaddr_in *)src)->sin_port; 3781 sin6->sin6_addr.s6_addr16[5] = htons(0xffff); 3782 bcopy(&((struct sockaddr_in *)src)->sin_addr, 3783 &sin6->sin6_addr.s6_addr32[3], 3784 sizeof(sin6->sin6_addr.s6_addr32[3])); 3785 } 3786 if (in6_pcbconnect(in6p, am, NULL)) { 3787 (void) m_free(am); 3788 goto resetandabort; 3789 } 3790 } 3791 #endif 3792 else { 3793 (void) m_free(am); 3794 goto resetandabort; 3795 } 3796 (void) m_free(am); 3797 3798 if (inp) 3799 tp = intotcpcb(inp); 3800 #ifdef INET6 3801 else if (in6p) 3802 tp = in6totcpcb(in6p); 3803 #endif 3804 else 3805 tp = NULL; 3806 tp->t_flags = sototcpcb(oso)->t_flags & TF_NODELAY; 3807 if (sc->sc_request_r_scale != 15) { 3808 tp->requested_s_scale = sc->sc_requested_s_scale; 3809 tp->request_r_scale = sc->sc_request_r_scale; 3810 tp->snd_scale = sc->sc_requested_s_scale; 3811 tp->rcv_scale = sc->sc_request_r_scale; 3812 tp->t_flags |= TF_REQ_SCALE|TF_RCVD_SCALE; 3813 } 3814 if (sc->sc_flags & SCF_TIMESTAMP) 3815 tp->t_flags |= TF_REQ_TSTMP|TF_RCVD_TSTMP; 3816 tp->ts_timebase = sc->sc_timebase; 3817 3818 tp->t_template = tcp_template(tp); 3819 if (tp->t_template == 0) { 3820 tp = tcp_drop(tp, ENOBUFS); /* destroys socket */ 3821 so = NULL; 3822 m_freem(m); 3823 goto abort; 3824 } 3825 3826 tp->iss = sc->sc_iss; 3827 tp->irs = sc->sc_irs; 3828 tcp_sendseqinit(tp); 3829 tcp_rcvseqinit(tp); 3830 tp->t_state = TCPS_SYN_RECEIVED; 3831 TCP_TIMER_ARM(tp, TCPT_KEEP, tp->t_keepinit); 3832 TCP_STATINC(TCP_STAT_ACCEPTS); 3833 3834 if ((sc->sc_flags & SCF_SACK_PERMIT) && tcp_do_sack) 3835 tp->t_flags |= TF_WILL_SACK; 3836 3837 if ((sc->sc_flags & SCF_ECN_PERMIT) && tcp_do_ecn) 3838 tp->t_flags |= TF_ECN_PERMIT; 3839 3840 #ifdef TCP_SIGNATURE 3841 if (sc->sc_flags & SCF_SIGNATURE) 3842 tp->t_flags |= TF_SIGNATURE; 3843 #endif 3844 3845 /* Initialize tp->t_ourmss before we deal with the peer's! */ 3846 tp->t_ourmss = sc->sc_ourmaxseg; 3847 tcp_mss_from_peer(tp, sc->sc_peermaxseg); 3848 3849 /* 3850 * Initialize the initial congestion window. If we 3851 * had to retransmit the SYN,ACK, we must initialize cwnd 3852 * to 1 segment (i.e. the Loss Window). 3853 */ 3854 if (sc->sc_rxtshift) 3855 tp->snd_cwnd = tp->t_peermss; 3856 else { 3857 int ss = tcp_init_win; 3858 #ifdef INET 3859 if (inp != NULL && in_localaddr(inp->inp_faddr)) 3860 ss = tcp_init_win_local; 3861 #endif 3862 #ifdef INET6 3863 if (in6p != NULL && in6_localaddr(&in6p->in6p_faddr)) 3864 ss = tcp_init_win_local; 3865 #endif 3866 tp->snd_cwnd = TCP_INITIAL_WINDOW(ss, tp->t_peermss); 3867 } 3868 3869 tcp_rmx_rtt(tp); 3870 tp->snd_wl1 = sc->sc_irs; 3871 tp->rcv_up = sc->sc_irs + 1; 3872 3873 /* 3874 * This is what whould have happened in tcp_output() when 3875 * the SYN,ACK was sent. 3876 */ 3877 tp->snd_up = tp->snd_una; 3878 tp->snd_max = tp->snd_nxt = tp->iss+1; 3879 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 3880 if (sc->sc_win > 0 && SEQ_GT(tp->rcv_nxt + sc->sc_win, tp->rcv_adv)) 3881 tp->rcv_adv = tp->rcv_nxt + sc->sc_win; 3882 tp->last_ack_sent = tp->rcv_nxt; 3883 tp->t_partialacks = -1; 3884 tp->t_dupacks = 0; 3885 3886 TCP_STATINC(TCP_STAT_SC_COMPLETED); 3887 s = splsoftnet(); 3888 syn_cache_put(sc); 3889 splx(s); 3890 return (so); 3891 3892 resetandabort: 3893 (void)tcp_respond(NULL, m, m, th, (tcp_seq)0, th->th_ack, TH_RST); 3894 abort: 3895 if (so != NULL) { 3896 (void) soqremque(so, 1); 3897 (void) soabort(so); 3898 mutex_enter(softnet_lock); 3899 } 3900 s = splsoftnet(); 3901 syn_cache_put(sc); 3902 splx(s); 3903 TCP_STATINC(TCP_STAT_SC_ABORTED); 3904 return ((struct socket *)(-1)); 3905 } 3906 3907 /* 3908 * This function is called when we get a RST for a 3909 * non-existent connection, so that we can see if the 3910 * connection is in the syn cache. If it is, zap it. 3911 */ 3912 3913 void 3914 syn_cache_reset(struct sockaddr *src, struct sockaddr *dst, struct tcphdr *th) 3915 { 3916 struct syn_cache *sc; 3917 struct syn_cache_head *scp; 3918 int s = splsoftnet(); 3919 3920 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 3921 splx(s); 3922 return; 3923 } 3924 if (SEQ_LT(th->th_seq, sc->sc_irs) || 3925 SEQ_GT(th->th_seq, sc->sc_irs+1)) { 3926 splx(s); 3927 return; 3928 } 3929 syn_cache_rm(sc); 3930 TCP_STATINC(TCP_STAT_SC_RESET); 3931 syn_cache_put(sc); /* calls pool_put but see spl above */ 3932 splx(s); 3933 } 3934 3935 void 3936 syn_cache_unreach(const struct sockaddr *src, const struct sockaddr *dst, 3937 struct tcphdr *th) 3938 { 3939 struct syn_cache *sc; 3940 struct syn_cache_head *scp; 3941 int s; 3942 3943 s = splsoftnet(); 3944 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 3945 splx(s); 3946 return; 3947 } 3948 /* If the sequence number != sc_iss, then it's a bogus ICMP msg */ 3949 if (ntohl (th->th_seq) != sc->sc_iss) { 3950 splx(s); 3951 return; 3952 } 3953 3954 /* 3955 * If we've retransmitted 3 times and this is our second error, 3956 * we remove the entry. Otherwise, we allow it to continue on. 3957 * This prevents us from incorrectly nuking an entry during a 3958 * spurious network outage. 3959 * 3960 * See tcp_notify(). 3961 */ 3962 if ((sc->sc_flags & SCF_UNREACH) == 0 || sc->sc_rxtshift < 3) { 3963 sc->sc_flags |= SCF_UNREACH; 3964 splx(s); 3965 return; 3966 } 3967 3968 syn_cache_rm(sc); 3969 TCP_STATINC(TCP_STAT_SC_UNREACH); 3970 syn_cache_put(sc); /* calls pool_put but see spl above */ 3971 splx(s); 3972 } 3973 3974 /* 3975 * Given a LISTEN socket and an inbound SYN request, add 3976 * this to the syn cache, and send back a segment: 3977 * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK> 3978 * to the source. 3979 * 3980 * IMPORTANT NOTE: We do _NOT_ ACK data that might accompany the SYN. 3981 * Doing so would require that we hold onto the data and deliver it 3982 * to the application. However, if we are the target of a SYN-flood 3983 * DoS attack, an attacker could send data which would eventually 3984 * consume all available buffer space if it were ACKed. By not ACKing 3985 * the data, we avoid this DoS scenario. 3986 */ 3987 3988 int 3989 syn_cache_add(struct sockaddr *src, struct sockaddr *dst, struct tcphdr *th, 3990 unsigned int hlen, struct socket *so, struct mbuf *m, u_char *optp, 3991 int optlen, struct tcp_opt_info *oi) 3992 { 3993 struct tcpcb tb, *tp; 3994 long win; 3995 struct syn_cache *sc; 3996 struct syn_cache_head *scp; 3997 struct mbuf *ipopts; 3998 struct tcp_opt_info opti; 3999 int s; 4000 4001 tp = sototcpcb(so); 4002 4003 bzero(&opti, sizeof(opti)); 4004 4005 /* 4006 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN 4007 * 4008 * Note this check is performed in tcp_input() very early on. 4009 */ 4010 4011 /* 4012 * Initialize some local state. 4013 */ 4014 win = sbspace(&so->so_rcv); 4015 if (win > TCP_MAXWIN) 4016 win = TCP_MAXWIN; 4017 4018 switch (src->sa_family) { 4019 #ifdef INET 4020 case AF_INET: 4021 /* 4022 * Remember the IP options, if any. 4023 */ 4024 ipopts = ip_srcroute(); 4025 break; 4026 #endif 4027 default: 4028 ipopts = NULL; 4029 } 4030 4031 #ifdef TCP_SIGNATURE 4032 if (optp || (tp->t_flags & TF_SIGNATURE)) 4033 #else 4034 if (optp) 4035 #endif 4036 { 4037 tb.t_flags = tcp_do_rfc1323 ? (TF_REQ_SCALE|TF_REQ_TSTMP) : 0; 4038 #ifdef TCP_SIGNATURE 4039 tb.t_flags |= (tp->t_flags & TF_SIGNATURE); 4040 #endif 4041 tb.t_state = TCPS_LISTEN; 4042 if (tcp_dooptions(&tb, optp, optlen, th, m, m->m_pkthdr.len - 4043 sizeof(struct tcphdr) - optlen - hlen, oi) < 0) 4044 return (0); 4045 } else 4046 tb.t_flags = 0; 4047 4048 /* 4049 * See if we already have an entry for this connection. 4050 * If we do, resend the SYN,ACK. We do not count this 4051 * as a retransmission (XXX though maybe we should). 4052 */ 4053 if ((sc = syn_cache_lookup(src, dst, &scp)) != NULL) { 4054 TCP_STATINC(TCP_STAT_SC_DUPESYN); 4055 if (ipopts) { 4056 /* 4057 * If we were remembering a previous source route, 4058 * forget it and use the new one we've been given. 4059 */ 4060 if (sc->sc_ipopts) 4061 (void) m_free(sc->sc_ipopts); 4062 sc->sc_ipopts = ipopts; 4063 } 4064 sc->sc_timestamp = tb.ts_recent; 4065 if (syn_cache_respond(sc, m) == 0) { 4066 uint64_t *tcps = TCP_STAT_GETREF(); 4067 tcps[TCP_STAT_SNDACKS]++; 4068 tcps[TCP_STAT_SNDTOTAL]++; 4069 TCP_STAT_PUTREF(); 4070 } 4071 return (1); 4072 } 4073 4074 s = splsoftnet(); 4075 sc = pool_get(&syn_cache_pool, PR_NOWAIT); 4076 splx(s); 4077 if (sc == NULL) { 4078 if (ipopts) 4079 (void) m_free(ipopts); 4080 return (0); 4081 } 4082 4083 /* 4084 * Fill in the cache, and put the necessary IP and TCP 4085 * options into the reply. 4086 */ 4087 bzero(sc, sizeof(struct syn_cache)); 4088 callout_init(&sc->sc_timer, CALLOUT_MPSAFE); 4089 bcopy(src, &sc->sc_src, src->sa_len); 4090 bcopy(dst, &sc->sc_dst, dst->sa_len); 4091 sc->sc_flags = 0; 4092 sc->sc_ipopts = ipopts; 4093 sc->sc_irs = th->th_seq; 4094 switch (src->sa_family) { 4095 #ifdef INET 4096 case AF_INET: 4097 { 4098 struct sockaddr_in *srcin = (void *) src; 4099 struct sockaddr_in *dstin = (void *) dst; 4100 4101 sc->sc_iss = tcp_new_iss1(&dstin->sin_addr, 4102 &srcin->sin_addr, dstin->sin_port, 4103 srcin->sin_port, sizeof(dstin->sin_addr), 0); 4104 break; 4105 } 4106 #endif /* INET */ 4107 #ifdef INET6 4108 case AF_INET6: 4109 { 4110 struct sockaddr_in6 *srcin6 = (void *) src; 4111 struct sockaddr_in6 *dstin6 = (void *) dst; 4112 4113 sc->sc_iss = tcp_new_iss1(&dstin6->sin6_addr, 4114 &srcin6->sin6_addr, dstin6->sin6_port, 4115 srcin6->sin6_port, sizeof(dstin6->sin6_addr), 0); 4116 break; 4117 } 4118 #endif /* INET6 */ 4119 } 4120 sc->sc_peermaxseg = oi->maxseg; 4121 sc->sc_ourmaxseg = tcp_mss_to_advertise(m->m_flags & M_PKTHDR ? 4122 m->m_pkthdr.rcvif : NULL, 4123 sc->sc_src.sa.sa_family); 4124 sc->sc_win = win; 4125 sc->sc_timebase = tcp_now - 1; /* see tcp_newtcpcb() */ 4126 sc->sc_timestamp = tb.ts_recent; 4127 if ((tb.t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP)) == 4128 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) 4129 sc->sc_flags |= SCF_TIMESTAMP; 4130 if ((tb.t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 4131 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 4132 sc->sc_requested_s_scale = tb.requested_s_scale; 4133 sc->sc_request_r_scale = 0; 4134 /* 4135 * Pick the smallest possible scaling factor that 4136 * will still allow us to scale up to sb_max. 4137 * 4138 * We do this because there are broken firewalls that 4139 * will corrupt the window scale option, leading to 4140 * the other endpoint believing that our advertised 4141 * window is unscaled. At scale factors larger than 4142 * 5 the unscaled window will drop below 1500 bytes, 4143 * leading to serious problems when traversing these 4144 * broken firewalls. 4145 * 4146 * With the default sbmax of 256K, a scale factor 4147 * of 3 will be chosen by this algorithm. Those who 4148 * choose a larger sbmax should watch out 4149 * for the compatiblity problems mentioned above. 4150 * 4151 * RFC1323: The Window field in a SYN (i.e., a <SYN> 4152 * or <SYN,ACK>) segment itself is never scaled. 4153 */ 4154 while (sc->sc_request_r_scale < TCP_MAX_WINSHIFT && 4155 (TCP_MAXWIN << sc->sc_request_r_scale) < sb_max) 4156 sc->sc_request_r_scale++; 4157 } else { 4158 sc->sc_requested_s_scale = 15; 4159 sc->sc_request_r_scale = 15; 4160 } 4161 if ((tb.t_flags & TF_SACK_PERMIT) && tcp_do_sack) 4162 sc->sc_flags |= SCF_SACK_PERMIT; 4163 4164 /* 4165 * ECN setup packet recieved. 4166 */ 4167 if ((th->th_flags & (TH_ECE|TH_CWR)) && tcp_do_ecn) 4168 sc->sc_flags |= SCF_ECN_PERMIT; 4169 4170 #ifdef TCP_SIGNATURE 4171 if (tb.t_flags & TF_SIGNATURE) 4172 sc->sc_flags |= SCF_SIGNATURE; 4173 #endif 4174 sc->sc_tp = tp; 4175 if (syn_cache_respond(sc, m) == 0) { 4176 uint64_t *tcps = TCP_STAT_GETREF(); 4177 tcps[TCP_STAT_SNDACKS]++; 4178 tcps[TCP_STAT_SNDTOTAL]++; 4179 TCP_STAT_PUTREF(); 4180 syn_cache_insert(sc, tp); 4181 } else { 4182 s = splsoftnet(); 4183 syn_cache_put(sc); 4184 splx(s); 4185 TCP_STATINC(TCP_STAT_SC_DROPPED); 4186 } 4187 return (1); 4188 } 4189 4190 int 4191 syn_cache_respond(struct syn_cache *sc, struct mbuf *m) 4192 { 4193 #ifdef INET6 4194 struct rtentry *rt; 4195 #endif 4196 struct route *ro; 4197 u_int8_t *optp; 4198 int optlen, error; 4199 u_int16_t tlen; 4200 struct ip *ip = NULL; 4201 #ifdef INET6 4202 struct ip6_hdr *ip6 = NULL; 4203 #endif 4204 struct tcpcb *tp = NULL; 4205 struct tcphdr *th; 4206 u_int hlen; 4207 struct socket *so; 4208 4209 ro = &sc->sc_route; 4210 switch (sc->sc_src.sa.sa_family) { 4211 case AF_INET: 4212 hlen = sizeof(struct ip); 4213 break; 4214 #ifdef INET6 4215 case AF_INET6: 4216 hlen = sizeof(struct ip6_hdr); 4217 break; 4218 #endif 4219 default: 4220 if (m) 4221 m_freem(m); 4222 return (EAFNOSUPPORT); 4223 } 4224 4225 /* Compute the size of the TCP options. */ 4226 optlen = 4 + (sc->sc_request_r_scale != 15 ? 4 : 0) + 4227 ((sc->sc_flags & SCF_SACK_PERMIT) ? (TCPOLEN_SACK_PERMITTED + 2) : 0) + 4228 #ifdef TCP_SIGNATURE 4229 ((sc->sc_flags & SCF_SIGNATURE) ? (TCPOLEN_SIGNATURE + 2) : 0) + 4230 #endif 4231 ((sc->sc_flags & SCF_TIMESTAMP) ? TCPOLEN_TSTAMP_APPA : 0); 4232 4233 tlen = hlen + sizeof(struct tcphdr) + optlen; 4234 4235 /* 4236 * Create the IP+TCP header from scratch. 4237 */ 4238 if (m) 4239 m_freem(m); 4240 #ifdef DIAGNOSTIC 4241 if (max_linkhdr + tlen > MCLBYTES) 4242 return (ENOBUFS); 4243 #endif 4244 MGETHDR(m, M_DONTWAIT, MT_DATA); 4245 if (m && tlen > MHLEN) { 4246 MCLGET(m, M_DONTWAIT); 4247 if ((m->m_flags & M_EXT) == 0) { 4248 m_freem(m); 4249 m = NULL; 4250 } 4251 } 4252 if (m == NULL) 4253 return (ENOBUFS); 4254 MCLAIM(m, &tcp_tx_mowner); 4255 4256 /* Fixup the mbuf. */ 4257 m->m_data += max_linkhdr; 4258 m->m_len = m->m_pkthdr.len = tlen; 4259 if (sc->sc_tp) { 4260 tp = sc->sc_tp; 4261 if (tp->t_inpcb) 4262 so = tp->t_inpcb->inp_socket; 4263 #ifdef INET6 4264 else if (tp->t_in6pcb) 4265 so = tp->t_in6pcb->in6p_socket; 4266 #endif 4267 else 4268 so = NULL; 4269 } else 4270 so = NULL; 4271 m->m_pkthdr.rcvif = NULL; 4272 memset(mtod(m, u_char *), 0, tlen); 4273 4274 switch (sc->sc_src.sa.sa_family) { 4275 case AF_INET: 4276 ip = mtod(m, struct ip *); 4277 ip->ip_v = 4; 4278 ip->ip_dst = sc->sc_src.sin.sin_addr; 4279 ip->ip_src = sc->sc_dst.sin.sin_addr; 4280 ip->ip_p = IPPROTO_TCP; 4281 th = (struct tcphdr *)(ip + 1); 4282 th->th_dport = sc->sc_src.sin.sin_port; 4283 th->th_sport = sc->sc_dst.sin.sin_port; 4284 break; 4285 #ifdef INET6 4286 case AF_INET6: 4287 ip6 = mtod(m, struct ip6_hdr *); 4288 ip6->ip6_vfc = IPV6_VERSION; 4289 ip6->ip6_dst = sc->sc_src.sin6.sin6_addr; 4290 ip6->ip6_src = sc->sc_dst.sin6.sin6_addr; 4291 ip6->ip6_nxt = IPPROTO_TCP; 4292 /* ip6_plen will be updated in ip6_output() */ 4293 th = (struct tcphdr *)(ip6 + 1); 4294 th->th_dport = sc->sc_src.sin6.sin6_port; 4295 th->th_sport = sc->sc_dst.sin6.sin6_port; 4296 break; 4297 #endif 4298 default: 4299 th = NULL; 4300 } 4301 4302 th->th_seq = htonl(sc->sc_iss); 4303 th->th_ack = htonl(sc->sc_irs + 1); 4304 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 4305 th->th_flags = TH_SYN|TH_ACK; 4306 th->th_win = htons(sc->sc_win); 4307 /* th_sum already 0 */ 4308 /* th_urp already 0 */ 4309 4310 /* Tack on the TCP options. */ 4311 optp = (u_int8_t *)(th + 1); 4312 *optp++ = TCPOPT_MAXSEG; 4313 *optp++ = 4; 4314 *optp++ = (sc->sc_ourmaxseg >> 8) & 0xff; 4315 *optp++ = sc->sc_ourmaxseg & 0xff; 4316 4317 if (sc->sc_request_r_scale != 15) { 4318 *((u_int32_t *)optp) = htonl(TCPOPT_NOP << 24 | 4319 TCPOPT_WINDOW << 16 | TCPOLEN_WINDOW << 8 | 4320 sc->sc_request_r_scale); 4321 optp += 4; 4322 } 4323 4324 if (sc->sc_flags & SCF_TIMESTAMP) { 4325 u_int32_t *lp = (u_int32_t *)(optp); 4326 /* Form timestamp option as shown in appendix A of RFC 1323. */ 4327 *lp++ = htonl(TCPOPT_TSTAMP_HDR); 4328 *lp++ = htonl(SYN_CACHE_TIMESTAMP(sc)); 4329 *lp = htonl(sc->sc_timestamp); 4330 optp += TCPOLEN_TSTAMP_APPA; 4331 } 4332 4333 if (sc->sc_flags & SCF_SACK_PERMIT) { 4334 u_int8_t *p = optp; 4335 4336 /* Let the peer know that we will SACK. */ 4337 p[0] = TCPOPT_SACK_PERMITTED; 4338 p[1] = 2; 4339 p[2] = TCPOPT_NOP; 4340 p[3] = TCPOPT_NOP; 4341 optp += 4; 4342 } 4343 4344 /* 4345 * Send ECN SYN-ACK setup packet. 4346 * Routes can be asymetric, so, even if we receive a packet 4347 * with ECE and CWR set, we must not assume no one will block 4348 * the ECE packet we are about to send. 4349 */ 4350 if ((sc->sc_flags & SCF_ECN_PERMIT) && tp && 4351 SEQ_GEQ(tp->snd_nxt, tp->snd_max)) { 4352 th->th_flags |= TH_ECE; 4353 TCP_STATINC(TCP_STAT_ECN_SHS); 4354 4355 /* 4356 * draft-ietf-tcpm-ecnsyn-00.txt 4357 * 4358 * "[...] a TCP node MAY respond to an ECN-setup 4359 * SYN packet by setting ECT in the responding 4360 * ECN-setup SYN/ACK packet, indicating to routers 4361 * that the SYN/ACK packet is ECN-Capable. 4362 * This allows a congested router along the path 4363 * to mark the packet instead of dropping the 4364 * packet as an indication of congestion." 4365 * 4366 * "[...] There can be a great benefit in setting 4367 * an ECN-capable codepoint in SYN/ACK packets [...] 4368 * Congestion is most likely to occur in 4369 * the server-to-client direction. As a result, 4370 * setting an ECN-capable codepoint in SYN/ACK 4371 * packets can reduce the occurence of three-second 4372 * retransmit timeouts resulting from the drop 4373 * of SYN/ACK packets." 4374 * 4375 * Page 4 and 6, January 2006. 4376 */ 4377 4378 switch (sc->sc_src.sa.sa_family) { 4379 #ifdef INET 4380 case AF_INET: 4381 ip->ip_tos |= IPTOS_ECN_ECT0; 4382 break; 4383 #endif 4384 #ifdef INET6 4385 case AF_INET6: 4386 ip6->ip6_flow |= htonl(IPTOS_ECN_ECT0 << 20); 4387 break; 4388 #endif 4389 } 4390 TCP_STATINC(TCP_STAT_ECN_ECT); 4391 } 4392 4393 #ifdef TCP_SIGNATURE 4394 if (sc->sc_flags & SCF_SIGNATURE) { 4395 struct secasvar *sav; 4396 u_int8_t *sigp; 4397 4398 sav = tcp_signature_getsav(m, th); 4399 4400 if (sav == NULL) { 4401 if (m) 4402 m_freem(m); 4403 return (EPERM); 4404 } 4405 4406 *optp++ = TCPOPT_SIGNATURE; 4407 *optp++ = TCPOLEN_SIGNATURE; 4408 sigp = optp; 4409 bzero(optp, TCP_SIGLEN); 4410 optp += TCP_SIGLEN; 4411 *optp++ = TCPOPT_NOP; 4412 *optp++ = TCPOPT_EOL; 4413 4414 (void)tcp_signature(m, th, hlen, sav, sigp); 4415 4416 key_sa_recordxfer(sav, m); 4417 #ifdef FAST_IPSEC 4418 KEY_FREESAV(&sav); 4419 #else 4420 key_freesav(sav); 4421 #endif 4422 } 4423 #endif 4424 4425 /* Compute the packet's checksum. */ 4426 switch (sc->sc_src.sa.sa_family) { 4427 case AF_INET: 4428 ip->ip_len = htons(tlen - hlen); 4429 th->th_sum = 0; 4430 th->th_sum = in4_cksum(m, IPPROTO_TCP, hlen, tlen - hlen); 4431 break; 4432 #ifdef INET6 4433 case AF_INET6: 4434 ip6->ip6_plen = htons(tlen - hlen); 4435 th->th_sum = 0; 4436 th->th_sum = in6_cksum(m, IPPROTO_TCP, hlen, tlen - hlen); 4437 break; 4438 #endif 4439 } 4440 4441 /* 4442 * Fill in some straggling IP bits. Note the stack expects 4443 * ip_len to be in host order, for convenience. 4444 */ 4445 switch (sc->sc_src.sa.sa_family) { 4446 #ifdef INET 4447 case AF_INET: 4448 ip->ip_len = htons(tlen); 4449 ip->ip_ttl = ip_defttl; 4450 /* XXX tos? */ 4451 break; 4452 #endif 4453 #ifdef INET6 4454 case AF_INET6: 4455 ip6->ip6_vfc &= ~IPV6_VERSION_MASK; 4456 ip6->ip6_vfc |= IPV6_VERSION; 4457 ip6->ip6_plen = htons(tlen - hlen); 4458 /* ip6_hlim will be initialized afterwards */ 4459 /* XXX flowlabel? */ 4460 break; 4461 #endif 4462 } 4463 4464 /* XXX use IPsec policy on listening socket, on SYN ACK */ 4465 tp = sc->sc_tp; 4466 4467 switch (sc->sc_src.sa.sa_family) { 4468 #ifdef INET 4469 case AF_INET: 4470 error = ip_output(m, sc->sc_ipopts, ro, 4471 (ip_mtudisc ? IP_MTUDISC : 0), 4472 (struct ip_moptions *)NULL, so); 4473 break; 4474 #endif 4475 #ifdef INET6 4476 case AF_INET6: 4477 ip6->ip6_hlim = in6_selecthlim(NULL, 4478 (rt = rtcache_validate(ro)) != NULL ? rt->rt_ifp 4479 : NULL); 4480 4481 error = ip6_output(m, NULL /*XXX*/, ro, 0, NULL, so, NULL); 4482 break; 4483 #endif 4484 default: 4485 error = EAFNOSUPPORT; 4486 break; 4487 } 4488 return (error); 4489 } 4490
Indexes created Wed Sep 24 05:09:52 GMT 2025