1 /* $NetBSD: tcp_input.c,v 1.244 2006/09/05 00:29:36 rpaulo 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 * 3. All advertising materials mentioning features or use of this software 93 * must display the following acknowledgement: 94 * This product includes software developed by the NetBSD 95 * Foundation, Inc. and its contributors. 96 * 4. Neither the name of The NetBSD Foundation nor the names of its 97 * contributors may be used to endorse or promote products derived 98 * from this software without specific prior written permission. 99 * 100 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 101 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 102 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 103 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 104 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 105 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 106 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 107 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 108 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 109 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 110 * POSSIBILITY OF SUCH DAMAGE. 111 */ 112 113 /* 114 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995 115 * The Regents of the University of California. All rights reserved. 116 * 117 * Redistribution and use in source and binary forms, with or without 118 * modification, are permitted provided that the following conditions 119 * are met: 120 * 1. Redistributions of source code must retain the above copyright 121 * notice, this list of conditions and the following disclaimer. 122 * 2. Redistributions in binary form must reproduce the above copyright 123 * notice, this list of conditions and the following disclaimer in the 124 * documentation and/or other materials provided with the distribution. 125 * 3. Neither the name of the University nor the names of its contributors 126 * may be used to endorse or promote products derived from this software 127 * without specific prior written permission. 128 * 129 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 130 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 131 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 132 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 133 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 134 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 135 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 136 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 137 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 138 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 139 * SUCH DAMAGE. 140 * 141 * @(#)tcp_input.c 8.12 (Berkeley) 5/24/95 142 */ 143 144 /* 145 * TODO list for SYN cache stuff: 146 * 147 * Find room for a "state" field, which is needed to keep a 148 * compressed state for TIME_WAIT TCBs. It's been noted already 149 * that this is fairly important for very high-volume web and 150 * mail servers, which use a large number of short-lived 151 * connections. 152 */ 153 154 #include <sys/cdefs.h> 155 __KERNEL_RCSID(0, "$NetBSD: tcp_input.c,v 1.244 2006/09/05 00:29:36 rpaulo Exp $"); 156 157 #include "opt_inet.h" 158 #include "opt_ipsec.h" 159 #include "opt_inet_csum.h" 160 #include "opt_tcp_debug.h" 161 162 #include <sys/param.h> 163 #include <sys/systm.h> 164 #include <sys/malloc.h> 165 #include <sys/mbuf.h> 166 #include <sys/protosw.h> 167 #include <sys/socket.h> 168 #include <sys/socketvar.h> 169 #include <sys/errno.h> 170 #include <sys/syslog.h> 171 #include <sys/pool.h> 172 #include <sys/domain.h> 173 #include <sys/kernel.h> 174 #ifdef TCP_SIGNATURE 175 #include <sys/md5.h> 176 #endif 177 178 #include <net/if.h> 179 #include <net/route.h> 180 #include <net/if_types.h> 181 182 #include <netinet/in.h> 183 #include <netinet/in_systm.h> 184 #include <netinet/ip.h> 185 #include <netinet/in_pcb.h> 186 #include <netinet/in_var.h> 187 #include <netinet/ip_var.h> 188 #include <netinet/in_offload.h> 189 190 #ifdef INET6 191 #ifndef INET 192 #include <netinet/in.h> 193 #endif 194 #include <netinet/ip6.h> 195 #include <netinet6/ip6_var.h> 196 #include <netinet6/in6_pcb.h> 197 #include <netinet6/ip6_var.h> 198 #include <netinet6/in6_var.h> 199 #include <netinet/icmp6.h> 200 #include <netinet6/nd6.h> 201 #ifdef TCP_SIGNATURE 202 #include <netinet6/scope6_var.h> 203 #endif 204 #endif 205 206 #ifndef INET6 207 /* always need ip6.h for IP6_EXTHDR_GET */ 208 #include <netinet/ip6.h> 209 #endif 210 211 #include <netinet/tcp.h> 212 #include <netinet/tcp_fsm.h> 213 #include <netinet/tcp_seq.h> 214 #include <netinet/tcp_timer.h> 215 #include <netinet/tcp_var.h> 216 #include <netinet/tcpip.h> 217 #include <netinet/tcp_debug.h> 218 219 #include <machine/stdarg.h> 220 221 #ifdef IPSEC 222 #include <netinet6/ipsec.h> 223 #include <netkey/key.h> 224 #endif /*IPSEC*/ 225 #ifdef INET6 226 #include "faith.h" 227 #if defined(NFAITH) && NFAITH > 0 228 #include <net/if_faith.h> 229 #endif 230 #endif /* IPSEC */ 231 232 #ifdef FAST_IPSEC 233 #include <netipsec/ipsec.h> 234 #include <netipsec/ipsec_var.h> /* XXX ipsecstat namespace */ 235 #include <netipsec/key.h> 236 #ifdef INET6 237 #include <netipsec/ipsec6.h> 238 #endif 239 #endif /* FAST_IPSEC*/ 240 241 static inline void tcp_congestion_exp(struct tcpcb *); 242 243 int tcprexmtthresh = 3; 244 int tcp_log_refused; 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 #define ND6_HINT(tp) \ 262 do { \ 263 if (tp && tp->t_in6pcb && tp->t_family == AF_INET6 && \ 264 tp->t_in6pcb->in6p_route.ro_rt) { \ 265 nd6_nud_hint(tp->t_in6pcb->in6p_route.ro_rt, NULL, 0); \ 266 } \ 267 } while (/*CONSTCOND*/ 0) 268 #else 269 #define ND6_HINT(tp) 270 #endif 271 272 /* 273 * Macro to compute ACK transmission behavior. Delay the ACK unless 274 * we have already delayed an ACK (must send an ACK every two segments). 275 * We also ACK immediately if we received a PUSH and the ACK-on-PUSH 276 * option is enabled. 277 */ 278 #define TCP_SETUP_ACK(tp, th) \ 279 do { \ 280 if ((tp)->t_flags & TF_DELACK || \ 281 (tcp_ack_on_push && (th)->th_flags & TH_PUSH)) \ 282 tp->t_flags |= TF_ACKNOW; \ 283 else \ 284 TCP_SET_DELACK(tp); \ 285 } while (/*CONSTCOND*/ 0) 286 287 #define ICMP_CHECK(tp, th, acked) \ 288 do { \ 289 /* \ 290 * If we had a pending ICMP message that \ 291 * refers to data that have just been \ 292 * acknowledged, disregard the recorded ICMP \ 293 * message. \ 294 */ \ 295 if (((tp)->t_flags & TF_PMTUD_PEND) && \ 296 SEQ_GT((th)->th_ack, (tp)->t_pmtud_th_seq)) \ 297 (tp)->t_flags &= ~TF_PMTUD_PEND; \ 298 \ 299 /* \ 300 * Keep track of the largest chunk of data \ 301 * acknowledged since last PMTU update \ 302 */ \ 303 if ((tp)->t_pmtud_mss_acked < (acked)) \ 304 (tp)->t_pmtud_mss_acked = (acked); \ 305 } while (/*CONSTCOND*/ 0) 306 307 /* 308 * Convert TCP protocol fields to host order for easier processing. 309 */ 310 #define TCP_FIELDS_TO_HOST(th) \ 311 do { \ 312 NTOHL((th)->th_seq); \ 313 NTOHL((th)->th_ack); \ 314 NTOHS((th)->th_win); \ 315 NTOHS((th)->th_urp); \ 316 } while (/*CONSTCOND*/ 0) 317 318 /* 319 * ... and reverse the above. 320 */ 321 #define TCP_FIELDS_TO_NET(th) \ 322 do { \ 323 HTONL((th)->th_seq); \ 324 HTONL((th)->th_ack); \ 325 HTONS((th)->th_win); \ 326 HTONS((th)->th_urp); \ 327 } while (/*CONSTCOND*/ 0) 328 329 #ifdef TCP_CSUM_COUNTERS 330 #include <sys/device.h> 331 332 #if defined(INET) 333 extern struct evcnt tcp_hwcsum_ok; 334 extern struct evcnt tcp_hwcsum_bad; 335 extern struct evcnt tcp_hwcsum_data; 336 extern struct evcnt tcp_swcsum; 337 #endif /* defined(INET) */ 338 #if defined(INET6) 339 extern struct evcnt tcp6_hwcsum_ok; 340 extern struct evcnt tcp6_hwcsum_bad; 341 extern struct evcnt tcp6_hwcsum_data; 342 extern struct evcnt tcp6_swcsum; 343 #endif /* defined(INET6) */ 344 345 #define TCP_CSUM_COUNTER_INCR(ev) (ev)->ev_count++ 346 347 #else 348 349 #define TCP_CSUM_COUNTER_INCR(ev) /* nothing */ 350 351 #endif /* TCP_CSUM_COUNTERS */ 352 353 #ifdef TCP_REASS_COUNTERS 354 #include <sys/device.h> 355 356 extern struct evcnt tcp_reass_; 357 extern struct evcnt tcp_reass_empty; 358 extern struct evcnt tcp_reass_iteration[8]; 359 extern struct evcnt tcp_reass_prependfirst; 360 extern struct evcnt tcp_reass_prepend; 361 extern struct evcnt tcp_reass_insert; 362 extern struct evcnt tcp_reass_inserttail; 363 extern struct evcnt tcp_reass_append; 364 extern struct evcnt tcp_reass_appendtail; 365 extern struct evcnt tcp_reass_overlaptail; 366 extern struct evcnt tcp_reass_overlapfront; 367 extern struct evcnt tcp_reass_segdup; 368 extern struct evcnt tcp_reass_fragdup; 369 370 #define TCP_REASS_COUNTER_INCR(ev) (ev)->ev_count++ 371 372 #else 373 374 #define TCP_REASS_COUNTER_INCR(ev) /* nothing */ 375 376 #endif /* TCP_REASS_COUNTERS */ 377 378 #ifdef INET 379 static void tcp4_log_refused(const struct ip *, const struct tcphdr *); 380 #endif 381 #ifdef INET6 382 static void tcp6_log_refused(const struct ip6_hdr *, const struct tcphdr *); 383 #endif 384 385 #define TRAVERSE(x) while ((x)->m_next) (x) = (x)->m_next 386 387 POOL_INIT(tcpipqent_pool, sizeof(struct ipqent), 0, 0, 0, "tcpipqepl", NULL); 388 389 struct ipqent * 390 tcpipqent_alloc() 391 { 392 struct ipqent *ipqe; 393 int s; 394 395 s = splvm(); 396 ipqe = pool_get(&tcpipqent_pool, PR_NOWAIT); 397 splx(s); 398 399 return ipqe; 400 } 401 402 void 403 tcpipqent_free(struct ipqent *ipqe) 404 { 405 int s; 406 407 s = splvm(); 408 pool_put(&tcpipqent_pool, ipqe); 409 splx(s); 410 } 411 412 /* 413 * Halve the congestion window and reduce the 414 * slow start threshold. 415 * 416 * Optionally, mark the packet. 417 */ 418 static inline void 419 tcp_congestion_exp(struct tcpcb *tp) 420 { 421 u_int win; 422 423 win = min(tp->snd_wnd, tp->snd_cwnd) / 2 / tp->t_segsz; 424 if (win < 2) 425 win = 2; 426 427 tp->snd_ssthresh = win * tp->t_segsz; 428 tp->snd_recover = tp->snd_max; 429 tp->snd_cwnd = tp->snd_ssthresh; 430 if (TCP_ECN_ALLOWED(tp)) 431 tp->t_flags |= TF_ECN_SND_CWR; 432 } 433 434 int 435 tcp_reass(struct tcpcb *tp, struct tcphdr *th, struct mbuf *m, int *tlen) 436 { 437 struct ipqent *p, *q, *nq, *tiqe = NULL; 438 struct socket *so = NULL; 439 int pkt_flags; 440 tcp_seq pkt_seq; 441 unsigned pkt_len; 442 u_long rcvpartdupbyte = 0; 443 u_long rcvoobyte; 444 #ifdef TCP_REASS_COUNTERS 445 u_int count = 0; 446 #endif 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 rcvoobyte = *tlen; 465 /* 466 * Copy these to local variables because the tcpiphdr 467 * gets munged while we are collapsing mbufs. 468 */ 469 pkt_seq = th->th_seq; 470 pkt_len = *tlen; 471 pkt_flags = th->th_flags; 472 473 TCP_REASS_COUNTER_INCR(&tcp_reass_); 474 475 if ((p = TAILQ_LAST(&tp->segq, ipqehead)) != NULL) { 476 /* 477 * When we miss a packet, the vast majority of time we get 478 * packets that follow it in order. So optimize for that. 479 */ 480 if (pkt_seq == p->ipqe_seq + p->ipqe_len) { 481 p->ipqe_len += pkt_len; 482 p->ipqe_flags |= pkt_flags; 483 m_cat(p->ipre_mlast, m); 484 TRAVERSE(p->ipre_mlast); 485 m = NULL; 486 tiqe = p; 487 TAILQ_REMOVE(&tp->timeq, p, ipqe_timeq); 488 TCP_REASS_COUNTER_INCR(&tcp_reass_appendtail); 489 goto skip_replacement; 490 } 491 /* 492 * While we're here, if the pkt is completely beyond 493 * anything we have, just insert it at the tail. 494 */ 495 if (SEQ_GT(pkt_seq, p->ipqe_seq + p->ipqe_len)) { 496 TCP_REASS_COUNTER_INCR(&tcp_reass_inserttail); 497 goto insert_it; 498 } 499 } 500 501 q = TAILQ_FIRST(&tp->segq); 502 503 if (q != NULL) { 504 /* 505 * If this segment immediately precedes the first out-of-order 506 * block, simply slap the segment in front of it and (mostly) 507 * skip the complicated logic. 508 */ 509 if (pkt_seq + pkt_len == q->ipqe_seq) { 510 q->ipqe_seq = pkt_seq; 511 q->ipqe_len += pkt_len; 512 q->ipqe_flags |= pkt_flags; 513 m_cat(m, q->ipqe_m); 514 q->ipqe_m = m; 515 q->ipre_mlast = m; /* last mbuf may have changed */ 516 TRAVERSE(q->ipre_mlast); 517 tiqe = q; 518 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 519 TCP_REASS_COUNTER_INCR(&tcp_reass_prependfirst); 520 goto skip_replacement; 521 } 522 } else { 523 TCP_REASS_COUNTER_INCR(&tcp_reass_empty); 524 } 525 526 /* 527 * Find a segment which begins after this one does. 528 */ 529 for (p = NULL; q != NULL; q = nq) { 530 nq = TAILQ_NEXT(q, ipqe_q); 531 #ifdef TCP_REASS_COUNTERS 532 count++; 533 #endif 534 /* 535 * If the received segment is just right after this 536 * fragment, merge the two together and then check 537 * for further overlaps. 538 */ 539 if (q->ipqe_seq + q->ipqe_len == pkt_seq) { 540 #ifdef TCPREASS_DEBUG 541 printf("tcp_reass[%p]: concat %u:%u(%u) to %u:%u(%u)\n", 542 tp, pkt_seq, pkt_seq + pkt_len, pkt_len, 543 q->ipqe_seq, q->ipqe_seq + q->ipqe_len, q->ipqe_len); 544 #endif 545 pkt_len += q->ipqe_len; 546 pkt_flags |= q->ipqe_flags; 547 pkt_seq = q->ipqe_seq; 548 m_cat(q->ipre_mlast, m); 549 TRAVERSE(q->ipre_mlast); 550 m = q->ipqe_m; 551 TCP_REASS_COUNTER_INCR(&tcp_reass_append); 552 goto free_ipqe; 553 } 554 /* 555 * If the received segment is completely past this 556 * fragment, we need to go the next fragment. 557 */ 558 if (SEQ_LT(q->ipqe_seq + q->ipqe_len, pkt_seq)) { 559 p = q; 560 continue; 561 } 562 /* 563 * If the fragment is past the received segment, 564 * it (or any following) can't be concatenated. 565 */ 566 if (SEQ_GT(q->ipqe_seq, pkt_seq + pkt_len)) { 567 TCP_REASS_COUNTER_INCR(&tcp_reass_insert); 568 break; 569 } 570 571 /* 572 * We've received all the data in this segment before. 573 * mark it as a duplicate and return. 574 */ 575 if (SEQ_LEQ(q->ipqe_seq, pkt_seq) && 576 SEQ_GEQ(q->ipqe_seq + q->ipqe_len, pkt_seq + pkt_len)) { 577 tcpstat.tcps_rcvduppack++; 578 tcpstat.tcps_rcvdupbyte += pkt_len; 579 tcp_new_dsack(tp, pkt_seq, pkt_len); 580 m_freem(m); 581 if (tiqe != NULL) { 582 tcpipqent_free(tiqe); 583 } 584 TCP_REASS_COUNTER_INCR(&tcp_reass_segdup); 585 return (0); 586 } 587 /* 588 * Received segment completely overlaps this fragment 589 * so we drop the fragment (this keeps the temporal 590 * ordering of segments correct). 591 */ 592 if (SEQ_GEQ(q->ipqe_seq, pkt_seq) && 593 SEQ_LEQ(q->ipqe_seq + q->ipqe_len, pkt_seq + pkt_len)) { 594 rcvpartdupbyte += q->ipqe_len; 595 m_freem(q->ipqe_m); 596 TCP_REASS_COUNTER_INCR(&tcp_reass_fragdup); 597 goto free_ipqe; 598 } 599 /* 600 * RX'ed segment extends past the end of the 601 * fragment. Drop the overlapping bytes. Then 602 * merge the fragment and segment then treat as 603 * a longer received packet. 604 */ 605 if (SEQ_LT(q->ipqe_seq, pkt_seq) && 606 SEQ_GT(q->ipqe_seq + q->ipqe_len, pkt_seq)) { 607 int overlap = q->ipqe_seq + q->ipqe_len - pkt_seq; 608 #ifdef TCPREASS_DEBUG 609 printf("tcp_reass[%p]: trim starting %d bytes of %u:%u(%u)\n", 610 tp, overlap, 611 pkt_seq, pkt_seq + pkt_len, pkt_len); 612 #endif 613 m_adj(m, overlap); 614 rcvpartdupbyte += overlap; 615 m_cat(q->ipre_mlast, m); 616 TRAVERSE(q->ipre_mlast); 617 m = q->ipqe_m; 618 pkt_seq = q->ipqe_seq; 619 pkt_len += q->ipqe_len - overlap; 620 rcvoobyte -= overlap; 621 TCP_REASS_COUNTER_INCR(&tcp_reass_overlaptail); 622 goto free_ipqe; 623 } 624 /* 625 * RX'ed segment extends past the front of the 626 * fragment. Drop the overlapping bytes on the 627 * received packet. The packet will then be 628 * contatentated with this fragment a bit later. 629 */ 630 if (SEQ_GT(q->ipqe_seq, pkt_seq) && 631 SEQ_LT(q->ipqe_seq, pkt_seq + pkt_len)) { 632 int overlap = pkt_seq + pkt_len - q->ipqe_seq; 633 #ifdef TCPREASS_DEBUG 634 printf("tcp_reass[%p]: trim trailing %d bytes of %u:%u(%u)\n", 635 tp, overlap, 636 pkt_seq, pkt_seq + pkt_len, pkt_len); 637 #endif 638 m_adj(m, -overlap); 639 pkt_len -= overlap; 640 rcvpartdupbyte += overlap; 641 TCP_REASS_COUNTER_INCR(&tcp_reass_overlapfront); 642 rcvoobyte -= overlap; 643 } 644 /* 645 * If the received segment immediates precedes this 646 * fragment then tack the fragment onto this segment 647 * and reinsert the data. 648 */ 649 if (q->ipqe_seq == pkt_seq + pkt_len) { 650 #ifdef TCPREASS_DEBUG 651 printf("tcp_reass[%p]: append %u:%u(%u) to %u:%u(%u)\n", 652 tp, q->ipqe_seq, q->ipqe_seq + q->ipqe_len, q->ipqe_len, 653 pkt_seq, pkt_seq + pkt_len, pkt_len); 654 #endif 655 pkt_len += q->ipqe_len; 656 pkt_flags |= q->ipqe_flags; 657 m_cat(m, q->ipqe_m); 658 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 659 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 660 tp->t_segqlen--; 661 KASSERT(tp->t_segqlen >= 0); 662 KASSERT(tp->t_segqlen != 0 || 663 (TAILQ_EMPTY(&tp->segq) && 664 TAILQ_EMPTY(&tp->timeq))); 665 if (tiqe == NULL) { 666 tiqe = q; 667 } else { 668 tcpipqent_free(q); 669 } 670 TCP_REASS_COUNTER_INCR(&tcp_reass_prepend); 671 break; 672 } 673 /* 674 * If the fragment is before the segment, remember it. 675 * When this loop is terminated, p will contain the 676 * pointer to fragment that is right before the received 677 * segment. 678 */ 679 if (SEQ_LEQ(q->ipqe_seq, pkt_seq)) 680 p = q; 681 682 continue; 683 684 /* 685 * This is a common operation. It also will allow 686 * to save doing a malloc/free in most instances. 687 */ 688 free_ipqe: 689 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 690 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 691 tp->t_segqlen--; 692 KASSERT(tp->t_segqlen >= 0); 693 KASSERT(tp->t_segqlen != 0 || 694 (TAILQ_EMPTY(&tp->segq) && TAILQ_EMPTY(&tp->timeq))); 695 if (tiqe == NULL) { 696 tiqe = q; 697 } else { 698 tcpipqent_free(q); 699 } 700 } 701 702 #ifdef TCP_REASS_COUNTERS 703 if (count > 7) 704 TCP_REASS_COUNTER_INCR(&tcp_reass_iteration[0]); 705 else if (count > 0) 706 TCP_REASS_COUNTER_INCR(&tcp_reass_iteration[count]); 707 #endif 708 709 insert_it: 710 711 /* 712 * Allocate a new queue entry since the received segment did not 713 * collapse onto any other out-of-order block; thus we are allocating 714 * a new block. If it had collapsed, tiqe would not be NULL and 715 * we would be reusing it. 716 * XXX If we can't, just drop the packet. XXX 717 */ 718 if (tiqe == NULL) { 719 tiqe = tcpipqent_alloc(); 720 if (tiqe == NULL) { 721 tcpstat.tcps_rcvmemdrop++; 722 m_freem(m); 723 return (0); 724 } 725 } 726 727 /* 728 * Update the counters. 729 */ 730 tcpstat.tcps_rcvoopack++; 731 tcpstat.tcps_rcvoobyte += rcvoobyte; 732 if (rcvpartdupbyte) { 733 tcpstat.tcps_rcvpartduppack++; 734 tcpstat.tcps_rcvpartdupbyte += rcvpartdupbyte; 735 } 736 737 /* 738 * Insert the new fragment queue entry into both queues. 739 */ 740 tiqe->ipqe_m = m; 741 tiqe->ipre_mlast = m; 742 tiqe->ipqe_seq = pkt_seq; 743 tiqe->ipqe_len = pkt_len; 744 tiqe->ipqe_flags = pkt_flags; 745 if (p == NULL) { 746 TAILQ_INSERT_HEAD(&tp->segq, tiqe, ipqe_q); 747 #ifdef TCPREASS_DEBUG 748 if (tiqe->ipqe_seq != tp->rcv_nxt) 749 printf("tcp_reass[%p]: insert %u:%u(%u) at front\n", 750 tp, pkt_seq, pkt_seq + pkt_len, pkt_len); 751 #endif 752 } else { 753 TAILQ_INSERT_AFTER(&tp->segq, p, tiqe, ipqe_q); 754 #ifdef TCPREASS_DEBUG 755 printf("tcp_reass[%p]: insert %u:%u(%u) after %u:%u(%u)\n", 756 tp, pkt_seq, pkt_seq + pkt_len, pkt_len, 757 p->ipqe_seq, p->ipqe_seq + p->ipqe_len, p->ipqe_len); 758 #endif 759 } 760 tp->t_segqlen++; 761 762 skip_replacement: 763 764 TAILQ_INSERT_HEAD(&tp->timeq, tiqe, ipqe_timeq); 765 766 present: 767 /* 768 * Present data to user, advancing rcv_nxt through 769 * completed sequence space. 770 */ 771 if (TCPS_HAVEESTABLISHED(tp->t_state) == 0) 772 return (0); 773 q = TAILQ_FIRST(&tp->segq); 774 if (q == NULL || q->ipqe_seq != tp->rcv_nxt) 775 return (0); 776 if (tp->t_state == TCPS_SYN_RECEIVED && q->ipqe_len) 777 return (0); 778 779 tp->rcv_nxt += q->ipqe_len; 780 pkt_flags = q->ipqe_flags & TH_FIN; 781 ND6_HINT(tp); 782 783 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 784 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 785 tp->t_segqlen--; 786 KASSERT(tp->t_segqlen >= 0); 787 KASSERT(tp->t_segqlen != 0 || 788 (TAILQ_EMPTY(&tp->segq) && TAILQ_EMPTY(&tp->timeq))); 789 if (so->so_state & SS_CANTRCVMORE) 790 m_freem(q->ipqe_m); 791 else 792 sbappendstream(&so->so_rcv, q->ipqe_m); 793 tcpipqent_free(q); 794 sorwakeup(so); 795 return (pkt_flags); 796 } 797 798 #ifdef INET6 799 int 800 tcp6_input(struct mbuf **mp, int *offp, int proto) 801 { 802 struct mbuf *m = *mp; 803 804 /* 805 * draft-itojun-ipv6-tcp-to-anycast 806 * better place to put this in? 807 */ 808 if (m->m_flags & M_ANYCAST6) { 809 struct ip6_hdr *ip6; 810 if (m->m_len < sizeof(struct ip6_hdr)) { 811 if ((m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) { 812 tcpstat.tcps_rcvshort++; 813 return IPPROTO_DONE; 814 } 815 } 816 ip6 = mtod(m, struct ip6_hdr *); 817 icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR, 818 (caddr_t)&ip6->ip6_dst - (caddr_t)ip6); 819 return IPPROTO_DONE; 820 } 821 822 tcp_input(m, *offp, proto); 823 return IPPROTO_DONE; 824 } 825 #endif 826 827 #ifdef INET 828 static void 829 tcp4_log_refused(const struct ip *ip, const struct tcphdr *th) 830 { 831 char src[4*sizeof "123"]; 832 char dst[4*sizeof "123"]; 833 834 if (ip) { 835 strlcpy(src, inet_ntoa(ip->ip_src), sizeof(src)); 836 strlcpy(dst, inet_ntoa(ip->ip_dst), sizeof(dst)); 837 } 838 else { 839 strlcpy(src, "(unknown)", sizeof(src)); 840 strlcpy(dst, "(unknown)", sizeof(dst)); 841 } 842 log(LOG_INFO, 843 "Connection attempt to TCP %s:%d from %s:%d\n", 844 dst, ntohs(th->th_dport), 845 src, ntohs(th->th_sport)); 846 } 847 #endif 848 849 #ifdef INET6 850 static void 851 tcp6_log_refused(const struct ip6_hdr *ip6, const struct tcphdr *th) 852 { 853 char src[INET6_ADDRSTRLEN]; 854 char dst[INET6_ADDRSTRLEN]; 855 856 if (ip6) { 857 strlcpy(src, ip6_sprintf(&ip6->ip6_src), sizeof(src)); 858 strlcpy(dst, ip6_sprintf(&ip6->ip6_dst), sizeof(dst)); 859 } 860 else { 861 strlcpy(src, "(unknown v6)", sizeof(src)); 862 strlcpy(dst, "(unknown v6)", sizeof(dst)); 863 } 864 log(LOG_INFO, 865 "Connection attempt to TCP [%s]:%d from [%s]:%d\n", 866 dst, ntohs(th->th_dport), 867 src, ntohs(th->th_sport)); 868 } 869 #endif 870 871 /* 872 * Checksum extended TCP header and data. 873 */ 874 int 875 tcp_input_checksum(int af, struct mbuf *m, const struct tcphdr *th, int toff, 876 int off, int tlen) 877 { 878 879 /* 880 * XXX it's better to record and check if this mbuf is 881 * already checked. 882 */ 883 884 switch (af) { 885 #ifdef INET 886 case AF_INET: 887 switch (m->m_pkthdr.csum_flags & 888 ((m->m_pkthdr.rcvif->if_csum_flags_rx & M_CSUM_TCPv4) | 889 M_CSUM_TCP_UDP_BAD | M_CSUM_DATA)) { 890 case M_CSUM_TCPv4|M_CSUM_TCP_UDP_BAD: 891 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_bad); 892 goto badcsum; 893 894 case M_CSUM_TCPv4|M_CSUM_DATA: { 895 u_int32_t hw_csum = m->m_pkthdr.csum_data; 896 897 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_data); 898 if (m->m_pkthdr.csum_flags & M_CSUM_NO_PSEUDOHDR) { 899 const struct ip *ip = 900 mtod(m, const struct ip *); 901 902 hw_csum = in_cksum_phdr(ip->ip_src.s_addr, 903 ip->ip_dst.s_addr, 904 htons(hw_csum + tlen + off + IPPROTO_TCP)); 905 } 906 if ((hw_csum ^ 0xffff) != 0) 907 goto badcsum; 908 break; 909 } 910 911 case M_CSUM_TCPv4: 912 /* Checksum was okay. */ 913 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_ok); 914 break; 915 916 default: 917 /* 918 * Must compute it ourselves. Maybe skip checksum 919 * on loopback interfaces. 920 */ 921 if (__predict_true(!(m->m_pkthdr.rcvif->if_flags & 922 IFF_LOOPBACK) || 923 tcp_do_loopback_cksum)) { 924 TCP_CSUM_COUNTER_INCR(&tcp_swcsum); 925 if (in4_cksum(m, IPPROTO_TCP, toff, 926 tlen + off) != 0) 927 goto badcsum; 928 } 929 break; 930 } 931 break; 932 #endif /* INET4 */ 933 934 #ifdef INET6 935 case AF_INET6: 936 switch (m->m_pkthdr.csum_flags & 937 ((m->m_pkthdr.rcvif->if_csum_flags_rx & M_CSUM_TCPv6) | 938 M_CSUM_TCP_UDP_BAD | M_CSUM_DATA)) { 939 case M_CSUM_TCPv6|M_CSUM_TCP_UDP_BAD: 940 TCP_CSUM_COUNTER_INCR(&tcp6_hwcsum_bad); 941 goto badcsum; 942 943 #if 0 /* notyet */ 944 case M_CSUM_TCPv6|M_CSUM_DATA: 945 #endif 946 947 case M_CSUM_TCPv6: 948 /* Checksum was okay. */ 949 TCP_CSUM_COUNTER_INCR(&tcp6_hwcsum_ok); 950 break; 951 952 default: 953 /* 954 * Must compute it ourselves. Maybe skip checksum 955 * on loopback interfaces. 956 */ 957 if (__predict_true((m->m_flags & M_LOOP) == 0 || 958 tcp_do_loopback_cksum)) { 959 TCP_CSUM_COUNTER_INCR(&tcp6_swcsum); 960 if (in6_cksum(m, IPPROTO_TCP, toff, 961 tlen + off) != 0) 962 goto badcsum; 963 } 964 } 965 break; 966 #endif /* INET6 */ 967 } 968 969 return 0; 970 971 badcsum: 972 tcpstat.tcps_rcvbadsum++; 973 return -1; 974 } 975 976 /* 977 * TCP input routine, follows pages 65-76 of RFC 793 very closely. 978 */ 979 void 980 tcp_input(struct mbuf *m, ...) 981 { 982 struct tcphdr *th; 983 struct ip *ip; 984 struct inpcb *inp; 985 #ifdef INET6 986 struct ip6_hdr *ip6; 987 struct in6pcb *in6p; 988 #endif 989 u_int8_t *optp = NULL; 990 int optlen = 0; 991 int len, tlen, toff, hdroptlen = 0; 992 struct tcpcb *tp = 0; 993 int tiflags; 994 struct socket *so = NULL; 995 int todrop, dupseg, acked, ourfinisacked, needoutput = 0; 996 #ifdef TCP_DEBUG 997 short ostate = 0; 998 #endif 999 u_long tiwin; 1000 struct tcp_opt_info opti; 1001 int off, iphlen; 1002 va_list ap; 1003 int af; /* af on the wire */ 1004 struct mbuf *tcp_saveti = NULL; 1005 uint32_t ts_rtt; 1006 uint8_t iptos; 1007 1008 MCLAIM(m, &tcp_rx_mowner); 1009 va_start(ap, m); 1010 toff = va_arg(ap, int); 1011 (void)va_arg(ap, int); /* ignore value, advance ap */ 1012 va_end(ap); 1013 1014 tcpstat.tcps_rcvtotal++; 1015 1016 bzero(&opti, sizeof(opti)); 1017 opti.ts_present = 0; 1018 opti.maxseg = 0; 1019 1020 /* 1021 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN. 1022 * 1023 * TCP is, by definition, unicast, so we reject all 1024 * multicast outright. 1025 * 1026 * Note, there are additional src/dst address checks in 1027 * the AF-specific code below. 1028 */ 1029 if (m->m_flags & (M_BCAST|M_MCAST)) { 1030 /* XXX stat */ 1031 goto drop; 1032 } 1033 #ifdef INET6 1034 if (m->m_flags & M_ANYCAST6) { 1035 /* XXX stat */ 1036 goto drop; 1037 } 1038 #endif 1039 1040 /* 1041 * Get IP and TCP header. 1042 * Note: IP leaves IP header in first mbuf. 1043 */ 1044 ip = mtod(m, struct ip *); 1045 #ifdef INET6 1046 ip6 = NULL; 1047 #endif 1048 switch (ip->ip_v) { 1049 #ifdef INET 1050 case 4: 1051 af = AF_INET; 1052 iphlen = sizeof(struct ip); 1053 ip = mtod(m, struct ip *); 1054 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, 1055 sizeof(struct tcphdr)); 1056 if (th == NULL) { 1057 tcpstat.tcps_rcvshort++; 1058 return; 1059 } 1060 /* We do the checksum after PCB lookup... */ 1061 len = ntohs(ip->ip_len); 1062 tlen = len - toff; 1063 iptos = ip->ip_tos; 1064 break; 1065 #endif 1066 #ifdef INET6 1067 case 6: 1068 ip = NULL; 1069 iphlen = sizeof(struct ip6_hdr); 1070 af = AF_INET6; 1071 ip6 = mtod(m, struct ip6_hdr *); 1072 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, 1073 sizeof(struct tcphdr)); 1074 if (th == NULL) { 1075 tcpstat.tcps_rcvshort++; 1076 return; 1077 } 1078 1079 /* Be proactive about malicious use of IPv4 mapped address */ 1080 if (IN6_IS_ADDR_V4MAPPED(&ip6->ip6_src) || 1081 IN6_IS_ADDR_V4MAPPED(&ip6->ip6_dst)) { 1082 /* XXX stat */ 1083 goto drop; 1084 } 1085 1086 /* 1087 * Be proactive about unspecified IPv6 address in source. 1088 * As we use all-zero to indicate unbounded/unconnected pcb, 1089 * unspecified IPv6 address can be used to confuse us. 1090 * 1091 * Note that packets with unspecified IPv6 destination is 1092 * already dropped in ip6_input. 1093 */ 1094 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 1095 /* XXX stat */ 1096 goto drop; 1097 } 1098 1099 /* 1100 * Make sure destination address is not multicast. 1101 * Source address checked in ip6_input(). 1102 */ 1103 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) { 1104 /* XXX stat */ 1105 goto drop; 1106 } 1107 1108 /* We do the checksum after PCB lookup... */ 1109 len = m->m_pkthdr.len; 1110 tlen = len - toff; 1111 iptos = (ntohl(ip6->ip6_flow) >> 20) & 0xff; 1112 break; 1113 #endif 1114 default: 1115 m_freem(m); 1116 return; 1117 } 1118 1119 KASSERT(TCP_HDR_ALIGNED_P(th)); 1120 1121 /* 1122 * Check that TCP offset makes sense, 1123 * pull out TCP options and adjust length. XXX 1124 */ 1125 off = th->th_off << 2; 1126 if (off < sizeof (struct tcphdr) || off > tlen) { 1127 tcpstat.tcps_rcvbadoff++; 1128 goto drop; 1129 } 1130 tlen -= off; 1131 1132 /* 1133 * tcp_input() has been modified to use tlen to mean the TCP data 1134 * length throughout the function. Other functions can use 1135 * m->m_pkthdr.len as the basis for calculating the TCP data length. 1136 * rja 1137 */ 1138 1139 if (off > sizeof (struct tcphdr)) { 1140 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, off); 1141 if (th == NULL) { 1142 tcpstat.tcps_rcvshort++; 1143 return; 1144 } 1145 /* 1146 * NOTE: ip/ip6 will not be affected by m_pulldown() 1147 * (as they're before toff) and we don't need to update those. 1148 */ 1149 KASSERT(TCP_HDR_ALIGNED_P(th)); 1150 optlen = off - sizeof (struct tcphdr); 1151 optp = ((u_int8_t *)th) + sizeof(struct tcphdr); 1152 /* 1153 * Do quick retrieval of timestamp options ("options 1154 * prediction?"). If timestamp is the only option and it's 1155 * formatted as recommended in RFC 1323 appendix A, we 1156 * quickly get the values now and not bother calling 1157 * tcp_dooptions(), etc. 1158 */ 1159 if ((optlen == TCPOLEN_TSTAMP_APPA || 1160 (optlen > TCPOLEN_TSTAMP_APPA && 1161 optp[TCPOLEN_TSTAMP_APPA] == TCPOPT_EOL)) && 1162 *(u_int32_t *)optp == htonl(TCPOPT_TSTAMP_HDR) && 1163 (th->th_flags & TH_SYN) == 0) { 1164 opti.ts_present = 1; 1165 opti.ts_val = ntohl(*(u_int32_t *)(optp + 4)); 1166 opti.ts_ecr = ntohl(*(u_int32_t *)(optp + 8)); 1167 optp = NULL; /* we've parsed the options */ 1168 } 1169 } 1170 tiflags = th->th_flags; 1171 1172 /* 1173 * Locate pcb for segment. 1174 */ 1175 findpcb: 1176 inp = NULL; 1177 #ifdef INET6 1178 in6p = NULL; 1179 #endif 1180 switch (af) { 1181 #ifdef INET 1182 case AF_INET: 1183 inp = in_pcblookup_connect(&tcbtable, ip->ip_src, th->th_sport, 1184 ip->ip_dst, th->th_dport); 1185 if (inp == 0) { 1186 ++tcpstat.tcps_pcbhashmiss; 1187 inp = in_pcblookup_bind(&tcbtable, ip->ip_dst, th->th_dport); 1188 } 1189 #ifdef INET6 1190 if (inp == 0) { 1191 struct in6_addr s, d; 1192 1193 /* mapped addr case */ 1194 bzero(&s, sizeof(s)); 1195 s.s6_addr16[5] = htons(0xffff); 1196 bcopy(&ip->ip_src, &s.s6_addr32[3], sizeof(ip->ip_src)); 1197 bzero(&d, sizeof(d)); 1198 d.s6_addr16[5] = htons(0xffff); 1199 bcopy(&ip->ip_dst, &d.s6_addr32[3], sizeof(ip->ip_dst)); 1200 in6p = in6_pcblookup_connect(&tcbtable, &s, 1201 th->th_sport, &d, th->th_dport, 0); 1202 if (in6p == 0) { 1203 ++tcpstat.tcps_pcbhashmiss; 1204 in6p = in6_pcblookup_bind(&tcbtable, &d, 1205 th->th_dport, 0); 1206 } 1207 } 1208 #endif 1209 #ifndef INET6 1210 if (inp == 0) 1211 #else 1212 if (inp == 0 && in6p == 0) 1213 #endif 1214 { 1215 ++tcpstat.tcps_noport; 1216 if (tcp_log_refused && 1217 (tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) { 1218 tcp4_log_refused(ip, th); 1219 } 1220 TCP_FIELDS_TO_HOST(th); 1221 goto dropwithreset_ratelim; 1222 } 1223 #if defined(IPSEC) || defined(FAST_IPSEC) 1224 if (inp && (inp->inp_socket->so_options & SO_ACCEPTCONN) == 0 && 1225 ipsec4_in_reject(m, inp)) { 1226 ipsecstat.in_polvio++; 1227 goto drop; 1228 } 1229 #ifdef INET6 1230 else if (in6p && 1231 (in6p->in6p_socket->so_options & SO_ACCEPTCONN) == 0 && 1232 ipsec4_in_reject_so(m, in6p->in6p_socket)) { 1233 ipsecstat.in_polvio++; 1234 goto drop; 1235 } 1236 #endif 1237 #endif /*IPSEC*/ 1238 break; 1239 #endif /*INET*/ 1240 #ifdef INET6 1241 case AF_INET6: 1242 { 1243 int faith; 1244 1245 #if defined(NFAITH) && NFAITH > 0 1246 faith = faithprefix(&ip6->ip6_dst); 1247 #else 1248 faith = 0; 1249 #endif 1250 in6p = in6_pcblookup_connect(&tcbtable, &ip6->ip6_src, 1251 th->th_sport, &ip6->ip6_dst, th->th_dport, faith); 1252 if (in6p == NULL) { 1253 ++tcpstat.tcps_pcbhashmiss; 1254 in6p = in6_pcblookup_bind(&tcbtable, &ip6->ip6_dst, 1255 th->th_dport, faith); 1256 } 1257 if (in6p == NULL) { 1258 ++tcpstat.tcps_noport; 1259 if (tcp_log_refused && 1260 (tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) { 1261 tcp6_log_refused(ip6, th); 1262 } 1263 TCP_FIELDS_TO_HOST(th); 1264 goto dropwithreset_ratelim; 1265 } 1266 #if defined(IPSEC) || defined(FAST_IPSEC) 1267 if ((in6p->in6p_socket->so_options & SO_ACCEPTCONN) == 0 && 1268 ipsec6_in_reject(m, in6p)) { 1269 ipsec6stat.in_polvio++; 1270 goto drop; 1271 } 1272 #endif /*IPSEC*/ 1273 break; 1274 } 1275 #endif 1276 } 1277 1278 /* 1279 * If the state is CLOSED (i.e., TCB does not exist) then 1280 * all data in the incoming segment is discarded. 1281 * If the TCB exists but is in CLOSED state, it is embryonic, 1282 * but should either do a listen or a connect soon. 1283 */ 1284 tp = NULL; 1285 so = NULL; 1286 if (inp) { 1287 tp = intotcpcb(inp); 1288 so = inp->inp_socket; 1289 } 1290 #ifdef INET6 1291 else if (in6p) { 1292 tp = in6totcpcb(in6p); 1293 so = in6p->in6p_socket; 1294 } 1295 #endif 1296 if (tp == 0) { 1297 TCP_FIELDS_TO_HOST(th); 1298 goto dropwithreset_ratelim; 1299 } 1300 if (tp->t_state == TCPS_CLOSED) 1301 goto drop; 1302 1303 /* 1304 * Checksum extended TCP header and data. 1305 */ 1306 if (tcp_input_checksum(af, m, th, toff, off, tlen)) 1307 goto badcsum; 1308 1309 TCP_FIELDS_TO_HOST(th); 1310 1311 /* Unscale the window into a 32-bit value. */ 1312 if ((tiflags & TH_SYN) == 0) 1313 tiwin = th->th_win << tp->snd_scale; 1314 else 1315 tiwin = th->th_win; 1316 1317 #ifdef INET6 1318 /* save packet options if user wanted */ 1319 if (in6p && (in6p->in6p_flags & IN6P_CONTROLOPTS)) { 1320 if (in6p->in6p_options) { 1321 m_freem(in6p->in6p_options); 1322 in6p->in6p_options = 0; 1323 } 1324 KASSERT(ip6 != NULL); 1325 ip6_savecontrol(in6p, &in6p->in6p_options, ip6, m); 1326 } 1327 #endif 1328 1329 if (so->so_options & (SO_DEBUG|SO_ACCEPTCONN)) { 1330 union syn_cache_sa src; 1331 union syn_cache_sa dst; 1332 1333 bzero(&src, sizeof(src)); 1334 bzero(&dst, sizeof(dst)); 1335 switch (af) { 1336 #ifdef INET 1337 case AF_INET: 1338 src.sin.sin_len = sizeof(struct sockaddr_in); 1339 src.sin.sin_family = AF_INET; 1340 src.sin.sin_addr = ip->ip_src; 1341 src.sin.sin_port = th->th_sport; 1342 1343 dst.sin.sin_len = sizeof(struct sockaddr_in); 1344 dst.sin.sin_family = AF_INET; 1345 dst.sin.sin_addr = ip->ip_dst; 1346 dst.sin.sin_port = th->th_dport; 1347 break; 1348 #endif 1349 #ifdef INET6 1350 case AF_INET6: 1351 src.sin6.sin6_len = sizeof(struct sockaddr_in6); 1352 src.sin6.sin6_family = AF_INET6; 1353 src.sin6.sin6_addr = ip6->ip6_src; 1354 src.sin6.sin6_port = th->th_sport; 1355 1356 dst.sin6.sin6_len = sizeof(struct sockaddr_in6); 1357 dst.sin6.sin6_family = AF_INET6; 1358 dst.sin6.sin6_addr = ip6->ip6_dst; 1359 dst.sin6.sin6_port = th->th_dport; 1360 break; 1361 #endif /* INET6 */ 1362 default: 1363 goto badsyn; /*sanity*/ 1364 } 1365 1366 if (so->so_options & SO_DEBUG) { 1367 #ifdef TCP_DEBUG 1368 ostate = tp->t_state; 1369 #endif 1370 1371 tcp_saveti = NULL; 1372 if (iphlen + sizeof(struct tcphdr) > MHLEN) 1373 goto nosave; 1374 1375 if (m->m_len > iphlen && (m->m_flags & M_EXT) == 0) { 1376 tcp_saveti = m_copym(m, 0, iphlen, M_DONTWAIT); 1377 if (!tcp_saveti) 1378 goto nosave; 1379 } else { 1380 MGETHDR(tcp_saveti, M_DONTWAIT, MT_HEADER); 1381 if (!tcp_saveti) 1382 goto nosave; 1383 MCLAIM(m, &tcp_mowner); 1384 tcp_saveti->m_len = iphlen; 1385 m_copydata(m, 0, iphlen, 1386 mtod(tcp_saveti, caddr_t)); 1387 } 1388 1389 if (M_TRAILINGSPACE(tcp_saveti) < sizeof(struct tcphdr)) { 1390 m_freem(tcp_saveti); 1391 tcp_saveti = NULL; 1392 } else { 1393 tcp_saveti->m_len += sizeof(struct tcphdr); 1394 bcopy(th, mtod(tcp_saveti, caddr_t) + iphlen, 1395 sizeof(struct tcphdr)); 1396 } 1397 nosave:; 1398 } 1399 if (so->so_options & SO_ACCEPTCONN) { 1400 if ((tiflags & (TH_RST|TH_ACK|TH_SYN)) != TH_SYN) { 1401 if (tiflags & TH_RST) { 1402 syn_cache_reset(&src.sa, &dst.sa, th); 1403 } else if ((tiflags & (TH_ACK|TH_SYN)) == 1404 (TH_ACK|TH_SYN)) { 1405 /* 1406 * Received a SYN,ACK. This should 1407 * never happen while we are in 1408 * LISTEN. Send an RST. 1409 */ 1410 goto badsyn; 1411 } else if (tiflags & TH_ACK) { 1412 so = syn_cache_get(&src.sa, &dst.sa, 1413 th, toff, tlen, so, m); 1414 if (so == NULL) { 1415 /* 1416 * We don't have a SYN for 1417 * this ACK; send an RST. 1418 */ 1419 goto badsyn; 1420 } else if (so == 1421 (struct socket *)(-1)) { 1422 /* 1423 * We were unable to create 1424 * the connection. If the 1425 * 3-way handshake was 1426 * completed, and RST has 1427 * been sent to the peer. 1428 * Since the mbuf might be 1429 * in use for the reply, 1430 * do not free it. 1431 */ 1432 m = NULL; 1433 } else { 1434 /* 1435 * We have created a 1436 * full-blown connection. 1437 */ 1438 tp = NULL; 1439 inp = NULL; 1440 #ifdef INET6 1441 in6p = NULL; 1442 #endif 1443 switch (so->so_proto->pr_domain->dom_family) { 1444 #ifdef INET 1445 case AF_INET: 1446 inp = sotoinpcb(so); 1447 tp = intotcpcb(inp); 1448 break; 1449 #endif 1450 #ifdef INET6 1451 case AF_INET6: 1452 in6p = sotoin6pcb(so); 1453 tp = in6totcpcb(in6p); 1454 break; 1455 #endif 1456 } 1457 if (tp == NULL) 1458 goto badsyn; /*XXX*/ 1459 tiwin <<= tp->snd_scale; 1460 goto after_listen; 1461 } 1462 } else { 1463 /* 1464 * None of RST, SYN or ACK was set. 1465 * This is an invalid packet for a 1466 * TCB in LISTEN state. Send a RST. 1467 */ 1468 goto badsyn; 1469 } 1470 } else { 1471 /* 1472 * Received a SYN. 1473 */ 1474 1475 #ifdef INET6 1476 /* 1477 * If deprecated address is forbidden, we do 1478 * not accept SYN to deprecated interface 1479 * address to prevent any new inbound 1480 * connection from getting established. 1481 * When we do not accept SYN, we send a TCP 1482 * RST, with deprecated source address (instead 1483 * of dropping it). We compromise it as it is 1484 * much better for peer to send a RST, and 1485 * RST will be the final packet for the 1486 * exchange. 1487 * 1488 * If we do not forbid deprecated addresses, we 1489 * accept the SYN packet. RFC2462 does not 1490 * suggest dropping SYN in this case. 1491 * If we decipher RFC2462 5.5.4, it says like 1492 * this: 1493 * 1. use of deprecated addr with existing 1494 * communication is okay - "SHOULD continue 1495 * to be used" 1496 * 2. use of it with new communication: 1497 * (2a) "SHOULD NOT be used if alternate 1498 * address with sufficient scope is 1499 * available" 1500 * (2b) nothing mentioned otherwise. 1501 * Here we fall into (2b) case as we have no 1502 * choice in our source address selection - we 1503 * must obey the peer. 1504 * 1505 * The wording in RFC2462 is confusing, and 1506 * there are multiple description text for 1507 * deprecated address handling - worse, they 1508 * are not exactly the same. I believe 5.5.4 1509 * is the best one, so we follow 5.5.4. 1510 */ 1511 if (af == AF_INET6 && !ip6_use_deprecated) { 1512 struct in6_ifaddr *ia6; 1513 if ((ia6 = in6ifa_ifpwithaddr(m->m_pkthdr.rcvif, 1514 &ip6->ip6_dst)) && 1515 (ia6->ia6_flags & IN6_IFF_DEPRECATED)) { 1516 tp = NULL; 1517 goto dropwithreset; 1518 } 1519 } 1520 #endif 1521 1522 #ifdef IPSEC 1523 switch (af) { 1524 #ifdef INET 1525 case AF_INET: 1526 if (ipsec4_in_reject_so(m, so)) { 1527 ipsecstat.in_polvio++; 1528 tp = NULL; 1529 goto dropwithreset; 1530 } 1531 break; 1532 #endif 1533 #ifdef INET6 1534 case AF_INET6: 1535 if (ipsec6_in_reject_so(m, so)) { 1536 ipsec6stat.in_polvio++; 1537 tp = NULL; 1538 goto dropwithreset; 1539 } 1540 break; 1541 #endif 1542 } 1543 #endif 1544 1545 /* 1546 * LISTEN socket received a SYN 1547 * from itself? This can't possibly 1548 * be valid; drop the packet. 1549 */ 1550 if (th->th_sport == th->th_dport) { 1551 int i; 1552 1553 switch (af) { 1554 #ifdef INET 1555 case AF_INET: 1556 i = in_hosteq(ip->ip_src, ip->ip_dst); 1557 break; 1558 #endif 1559 #ifdef INET6 1560 case AF_INET6: 1561 i = IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &ip6->ip6_dst); 1562 break; 1563 #endif 1564 default: 1565 i = 1; 1566 } 1567 if (i) { 1568 tcpstat.tcps_badsyn++; 1569 goto drop; 1570 } 1571 } 1572 1573 /* 1574 * SYN looks ok; create compressed TCP 1575 * state for it. 1576 */ 1577 if (so->so_qlen <= so->so_qlimit && 1578 syn_cache_add(&src.sa, &dst.sa, th, tlen, 1579 so, m, optp, optlen, &opti)) 1580 m = NULL; 1581 } 1582 goto drop; 1583 } 1584 } 1585 1586 after_listen: 1587 #ifdef DIAGNOSTIC 1588 /* 1589 * Should not happen now that all embryonic connections 1590 * are handled with compressed state. 1591 */ 1592 if (tp->t_state == TCPS_LISTEN) 1593 panic("tcp_input: TCPS_LISTEN"); 1594 #endif 1595 1596 /* 1597 * Segment received on connection. 1598 * Reset idle time and keep-alive timer. 1599 */ 1600 tp->t_rcvtime = tcp_now; 1601 if (TCPS_HAVEESTABLISHED(tp->t_state)) 1602 TCP_TIMER_ARM(tp, TCPT_KEEP, tcp_keepidle); 1603 1604 /* 1605 * Process options. 1606 */ 1607 #ifdef TCP_SIGNATURE 1608 if (optp || (tp->t_flags & TF_SIGNATURE)) 1609 #else 1610 if (optp) 1611 #endif 1612 if (tcp_dooptions(tp, optp, optlen, th, m, toff, &opti) < 0) 1613 goto drop; 1614 1615 if (TCP_SACK_ENABLED(tp)) { 1616 tcp_del_sackholes(tp, th); 1617 } 1618 1619 if (TCP_ECN_ALLOWED(tp)) { 1620 switch (iptos & IPTOS_ECN_MASK) { 1621 case IPTOS_ECN_CE: 1622 tp->t_flags |= TF_ECN_SND_ECE; 1623 tcpstat.tcps_ecn_ce++; 1624 break; 1625 case IPTOS_ECN_ECT0: 1626 tcpstat.tcps_ecn_ect++; 1627 break; 1628 case IPTOS_ECN_ECT1: 1629 /* XXX: ignore for now -- rpaulo */ 1630 break; 1631 } 1632 1633 if (tiflags & TH_CWR) 1634 tp->t_flags &= ~TF_ECN_SND_ECE; 1635 1636 /* 1637 * Congestion experienced. 1638 * Ignore if we are already trying to recover. 1639 */ 1640 if ((tiflags & TH_ECE) && SEQ_GEQ(tp->snd_una, tp->snd_recover)) 1641 tcp_congestion_exp(tp); 1642 } 1643 1644 if (opti.ts_present && opti.ts_ecr) { 1645 /* 1646 * Calculate the RTT from the returned time stamp and the 1647 * connection's time base. If the time stamp is later than 1648 * the current time, or is extremely old, fall back to non-1323 1649 * RTT calculation. Since ts_ecr is unsigned, we can test both 1650 * at the same time. 1651 */ 1652 ts_rtt = TCP_TIMESTAMP(tp) - opti.ts_ecr + 1; 1653 if (ts_rtt > TCP_PAWS_IDLE) 1654 ts_rtt = 0; 1655 } else { 1656 ts_rtt = 0; 1657 } 1658 1659 /* 1660 * Header prediction: check for the two common cases 1661 * of a uni-directional data xfer. If the packet has 1662 * no control flags, is in-sequence, the window didn't 1663 * change and we're not retransmitting, it's a 1664 * candidate. If the length is zero and the ack moved 1665 * forward, we're the sender side of the xfer. Just 1666 * free the data acked & wake any higher level process 1667 * that was blocked waiting for space. If the length 1668 * is non-zero and the ack didn't move, we're the 1669 * receiver side. If we're getting packets in-order 1670 * (the reassembly queue is empty), add the data to 1671 * the socket buffer and note that we need a delayed ack. 1672 */ 1673 if (tp->t_state == TCPS_ESTABLISHED && 1674 (tiflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ECE|TH_CWR|TH_ACK)) 1675 == TH_ACK && 1676 (!opti.ts_present || TSTMP_GEQ(opti.ts_val, tp->ts_recent)) && 1677 th->th_seq == tp->rcv_nxt && 1678 tiwin && tiwin == tp->snd_wnd && 1679 tp->snd_nxt == tp->snd_max) { 1680 1681 /* 1682 * If last ACK falls within this segment's sequence numbers, 1683 * record the timestamp. 1684 * NOTE: 1685 * 1) That the test incorporates suggestions from the latest 1686 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 1687 * 2) That updating only on newer timestamps interferes with 1688 * our earlier PAWS tests, so this check should be solely 1689 * predicated on the sequence space of this segment. 1690 * 3) That we modify the segment boundary check to be 1691 * Last.ACK.Sent <= SEG.SEQ + SEG.Len 1692 * instead of RFC1323's 1693 * Last.ACK.Sent < SEG.SEQ + SEG.Len, 1694 * This modified check allows us to overcome RFC1323's 1695 * limitations as described in Stevens TCP/IP Illustrated 1696 * Vol. 2 p.869. In such cases, we can still calculate the 1697 * RTT correctly when RCV.NXT == Last.ACK.Sent. 1698 */ 1699 if (opti.ts_present && 1700 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 1701 SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen + 1702 ((tiflags & (TH_SYN|TH_FIN)) != 0))) { 1703 tp->ts_recent_age = tcp_now; 1704 tp->ts_recent = opti.ts_val; 1705 } 1706 1707 if (tlen == 0) { 1708 /* Ack prediction. */ 1709 if (SEQ_GT(th->th_ack, tp->snd_una) && 1710 SEQ_LEQ(th->th_ack, tp->snd_max) && 1711 tp->snd_cwnd >= tp->snd_wnd && 1712 tp->t_partialacks < 0) { 1713 /* 1714 * this is a pure ack for outstanding data. 1715 */ 1716 ++tcpstat.tcps_predack; 1717 if (ts_rtt) 1718 tcp_xmit_timer(tp, ts_rtt); 1719 else if (tp->t_rtttime && 1720 SEQ_GT(th->th_ack, tp->t_rtseq)) 1721 tcp_xmit_timer(tp, 1722 tcp_now - tp->t_rtttime); 1723 acked = th->th_ack - tp->snd_una; 1724 tcpstat.tcps_rcvackpack++; 1725 tcpstat.tcps_rcvackbyte += acked; 1726 ND6_HINT(tp); 1727 1728 if (acked > (tp->t_lastoff - tp->t_inoff)) 1729 tp->t_lastm = NULL; 1730 sbdrop(&so->so_snd, acked); 1731 tp->t_lastoff -= acked; 1732 1733 ICMP_CHECK(tp, th, acked); 1734 1735 tp->snd_una = th->th_ack; 1736 tp->snd_fack = tp->snd_una; 1737 if (SEQ_LT(tp->snd_high, tp->snd_una)) 1738 tp->snd_high = tp->snd_una; 1739 m_freem(m); 1740 1741 /* 1742 * If all outstanding data are acked, stop 1743 * retransmit timer, otherwise restart timer 1744 * using current (possibly backed-off) value. 1745 * If process is waiting for space, 1746 * wakeup/selwakeup/signal. If data 1747 * are ready to send, let tcp_output 1748 * decide between more output or persist. 1749 */ 1750 if (tp->snd_una == tp->snd_max) 1751 TCP_TIMER_DISARM(tp, TCPT_REXMT); 1752 else if (TCP_TIMER_ISARMED(tp, 1753 TCPT_PERSIST) == 0) 1754 TCP_TIMER_ARM(tp, TCPT_REXMT, 1755 tp->t_rxtcur); 1756 1757 sowwakeup(so); 1758 if (so->so_snd.sb_cc) 1759 (void) tcp_output(tp); 1760 if (tcp_saveti) 1761 m_freem(tcp_saveti); 1762 return; 1763 } 1764 } else if (th->th_ack == tp->snd_una && 1765 TAILQ_FIRST(&tp->segq) == NULL && 1766 tlen <= sbspace(&so->so_rcv)) { 1767 /* 1768 * this is a pure, in-sequence data packet 1769 * with nothing on the reassembly queue and 1770 * we have enough buffer space to take it. 1771 */ 1772 ++tcpstat.tcps_preddat; 1773 tp->rcv_nxt += tlen; 1774 tcpstat.tcps_rcvpack++; 1775 tcpstat.tcps_rcvbyte += tlen; 1776 ND6_HINT(tp); 1777 /* 1778 * Drop TCP, IP headers and TCP options then add data 1779 * to socket buffer. 1780 */ 1781 if (so->so_state & SS_CANTRCVMORE) 1782 m_freem(m); 1783 else { 1784 m_adj(m, toff + off); 1785 sbappendstream(&so->so_rcv, m); 1786 } 1787 sorwakeup(so); 1788 TCP_SETUP_ACK(tp, th); 1789 if (tp->t_flags & TF_ACKNOW) 1790 (void) tcp_output(tp); 1791 if (tcp_saveti) 1792 m_freem(tcp_saveti); 1793 return; 1794 } 1795 } 1796 1797 /* 1798 * Compute mbuf offset to TCP data segment. 1799 */ 1800 hdroptlen = toff + off; 1801 1802 /* 1803 * Calculate amount of space in receive window, 1804 * and then do TCP input processing. 1805 * Receive window is amount of space in rcv queue, 1806 * but not less than advertised window. 1807 */ 1808 { int win; 1809 1810 win = sbspace(&so->so_rcv); 1811 if (win < 0) 1812 win = 0; 1813 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 1814 } 1815 1816 switch (tp->t_state) { 1817 case TCPS_LISTEN: 1818 /* 1819 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN 1820 */ 1821 if (m->m_flags & (M_BCAST|M_MCAST)) 1822 goto drop; 1823 switch (af) { 1824 #ifdef INET6 1825 case AF_INET6: 1826 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) 1827 goto drop; 1828 break; 1829 #endif /* INET6 */ 1830 case AF_INET: 1831 if (IN_MULTICAST(ip->ip_dst.s_addr) || 1832 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 1833 goto drop; 1834 break; 1835 } 1836 break; 1837 1838 /* 1839 * If the state is SYN_SENT: 1840 * if seg contains an ACK, but not for our SYN, drop the input. 1841 * if seg contains a RST, then drop the connection. 1842 * if seg does not contain SYN, then drop it. 1843 * Otherwise this is an acceptable SYN segment 1844 * initialize tp->rcv_nxt and tp->irs 1845 * if seg contains ack then advance tp->snd_una 1846 * if seg contains a ECE and ECN support is enabled, the stream 1847 * is ECN capable. 1848 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 1849 * arrange for segment to be acked (eventually) 1850 * continue processing rest of data/controls, beginning with URG 1851 */ 1852 case TCPS_SYN_SENT: 1853 if ((tiflags & TH_ACK) && 1854 (SEQ_LEQ(th->th_ack, tp->iss) || 1855 SEQ_GT(th->th_ack, tp->snd_max))) 1856 goto dropwithreset; 1857 if (tiflags & TH_RST) { 1858 if (tiflags & TH_ACK) 1859 tp = tcp_drop(tp, ECONNREFUSED); 1860 goto drop; 1861 } 1862 if ((tiflags & TH_SYN) == 0) 1863 goto drop; 1864 if (tiflags & TH_ACK) { 1865 tp->snd_una = th->th_ack; 1866 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 1867 tp->snd_nxt = tp->snd_una; 1868 if (SEQ_LT(tp->snd_high, tp->snd_una)) 1869 tp->snd_high = tp->snd_una; 1870 TCP_TIMER_DISARM(tp, TCPT_REXMT); 1871 1872 if ((tiflags & TH_ECE) && tcp_do_ecn) { 1873 tp->t_flags |= TF_ECN_PERMIT; 1874 tcpstat.tcps_ecn_shs++; 1875 } 1876 1877 } 1878 tp->irs = th->th_seq; 1879 tcp_rcvseqinit(tp); 1880 tp->t_flags |= TF_ACKNOW; 1881 tcp_mss_from_peer(tp, opti.maxseg); 1882 1883 /* 1884 * Initialize the initial congestion window. If we 1885 * had to retransmit the SYN, we must initialize cwnd 1886 * to 1 segment (i.e. the Loss Window). 1887 */ 1888 if (tp->t_flags & TF_SYN_REXMT) 1889 tp->snd_cwnd = tp->t_peermss; 1890 else { 1891 int ss = tcp_init_win; 1892 #ifdef INET 1893 if (inp != NULL && in_localaddr(inp->inp_faddr)) 1894 ss = tcp_init_win_local; 1895 #endif 1896 #ifdef INET6 1897 if (in6p != NULL && in6_localaddr(&in6p->in6p_faddr)) 1898 ss = tcp_init_win_local; 1899 #endif 1900 tp->snd_cwnd = TCP_INITIAL_WINDOW(ss, tp->t_peermss); 1901 } 1902 1903 tcp_rmx_rtt(tp); 1904 if (tiflags & TH_ACK) { 1905 tcpstat.tcps_connects++; 1906 soisconnected(so); 1907 tcp_established(tp); 1908 /* Do window scaling on this connection? */ 1909 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 1910 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 1911 tp->snd_scale = tp->requested_s_scale; 1912 tp->rcv_scale = tp->request_r_scale; 1913 } 1914 TCP_REASS_LOCK(tp); 1915 (void) tcp_reass(tp, NULL, (struct mbuf *)0, &tlen); 1916 TCP_REASS_UNLOCK(tp); 1917 /* 1918 * if we didn't have to retransmit the SYN, 1919 * use its rtt as our initial srtt & rtt var. 1920 */ 1921 if (tp->t_rtttime) 1922 tcp_xmit_timer(tp, tcp_now - tp->t_rtttime); 1923 } else 1924 tp->t_state = TCPS_SYN_RECEIVED; 1925 1926 /* 1927 * Advance th->th_seq to correspond to first data byte. 1928 * If data, trim to stay within window, 1929 * dropping FIN if necessary. 1930 */ 1931 th->th_seq++; 1932 if (tlen > tp->rcv_wnd) { 1933 todrop = tlen - tp->rcv_wnd; 1934 m_adj(m, -todrop); 1935 tlen = tp->rcv_wnd; 1936 tiflags &= ~TH_FIN; 1937 tcpstat.tcps_rcvpackafterwin++; 1938 tcpstat.tcps_rcvbyteafterwin += todrop; 1939 } 1940 tp->snd_wl1 = th->th_seq - 1; 1941 tp->rcv_up = th->th_seq; 1942 goto step6; 1943 1944 /* 1945 * If the state is SYN_RECEIVED: 1946 * If seg contains an ACK, but not for our SYN, drop the input 1947 * and generate an RST. See page 36, rfc793 1948 */ 1949 case TCPS_SYN_RECEIVED: 1950 if ((tiflags & TH_ACK) && 1951 (SEQ_LEQ(th->th_ack, tp->iss) || 1952 SEQ_GT(th->th_ack, tp->snd_max))) 1953 goto dropwithreset; 1954 break; 1955 } 1956 1957 /* 1958 * States other than LISTEN or SYN_SENT. 1959 * First check timestamp, if present. 1960 * Then check that at least some bytes of segment are within 1961 * receive window. If segment begins before rcv_nxt, 1962 * drop leading data (and SYN); if nothing left, just ack. 1963 * 1964 * RFC 1323 PAWS: If we have a timestamp reply on this segment 1965 * and it's less than ts_recent, drop it. 1966 */ 1967 if (opti.ts_present && (tiflags & TH_RST) == 0 && tp->ts_recent && 1968 TSTMP_LT(opti.ts_val, tp->ts_recent)) { 1969 1970 /* Check to see if ts_recent is over 24 days old. */ 1971 if (tcp_now - tp->ts_recent_age > TCP_PAWS_IDLE) { 1972 /* 1973 * Invalidate ts_recent. If this segment updates 1974 * ts_recent, the age will be reset later and ts_recent 1975 * will get a valid value. If it does not, setting 1976 * ts_recent to zero will at least satisfy the 1977 * requirement that zero be placed in the timestamp 1978 * echo reply when ts_recent isn't valid. The 1979 * age isn't reset until we get a valid ts_recent 1980 * because we don't want out-of-order segments to be 1981 * dropped when ts_recent is old. 1982 */ 1983 tp->ts_recent = 0; 1984 } else { 1985 tcpstat.tcps_rcvduppack++; 1986 tcpstat.tcps_rcvdupbyte += tlen; 1987 tcpstat.tcps_pawsdrop++; 1988 tcp_new_dsack(tp, th->th_seq, tlen); 1989 goto dropafterack; 1990 } 1991 } 1992 1993 todrop = tp->rcv_nxt - th->th_seq; 1994 dupseg = FALSE; 1995 if (todrop > 0) { 1996 if (tiflags & TH_SYN) { 1997 tiflags &= ~TH_SYN; 1998 th->th_seq++; 1999 if (th->th_urp > 1) 2000 th->th_urp--; 2001 else { 2002 tiflags &= ~TH_URG; 2003 th->th_urp = 0; 2004 } 2005 todrop--; 2006 } 2007 if (todrop > tlen || 2008 (todrop == tlen && (tiflags & TH_FIN) == 0)) { 2009 /* 2010 * Any valid FIN or RST must be to the left of the 2011 * window. At this point the FIN or RST must be a 2012 * duplicate or out of sequence; drop it. 2013 */ 2014 if (tiflags & TH_RST) 2015 goto drop; 2016 tiflags &= ~(TH_FIN|TH_RST); 2017 /* 2018 * Send an ACK to resynchronize and drop any data. 2019 * But keep on processing for RST or ACK. 2020 */ 2021 tp->t_flags |= TF_ACKNOW; 2022 todrop = tlen; 2023 dupseg = TRUE; 2024 tcpstat.tcps_rcvdupbyte += todrop; 2025 tcpstat.tcps_rcvduppack++; 2026 } else if ((tiflags & TH_RST) && 2027 th->th_seq != tp->last_ack_sent) { 2028 /* 2029 * Test for reset before adjusting the sequence 2030 * number for overlapping data. 2031 */ 2032 goto dropafterack_ratelim; 2033 } else { 2034 tcpstat.tcps_rcvpartduppack++; 2035 tcpstat.tcps_rcvpartdupbyte += todrop; 2036 } 2037 tcp_new_dsack(tp, th->th_seq, todrop); 2038 hdroptlen += todrop; /*drop from head afterwards*/ 2039 th->th_seq += todrop; 2040 tlen -= todrop; 2041 if (th->th_urp > todrop) 2042 th->th_urp -= todrop; 2043 else { 2044 tiflags &= ~TH_URG; 2045 th->th_urp = 0; 2046 } 2047 } 2048 2049 /* 2050 * If new data are received on a connection after the 2051 * user processes are gone, then RST the other end. 2052 */ 2053 if ((so->so_state & SS_NOFDREF) && 2054 tp->t_state > TCPS_CLOSE_WAIT && tlen) { 2055 tp = tcp_close(tp); 2056 tcpstat.tcps_rcvafterclose++; 2057 goto dropwithreset; 2058 } 2059 2060 /* 2061 * If segment ends after window, drop trailing data 2062 * (and PUSH and FIN); if nothing left, just ACK. 2063 */ 2064 todrop = (th->th_seq + tlen) - (tp->rcv_nxt+tp->rcv_wnd); 2065 if (todrop > 0) { 2066 tcpstat.tcps_rcvpackafterwin++; 2067 if (todrop >= tlen) { 2068 /* 2069 * The segment actually starts after the window. 2070 * th->th_seq + tlen - tp->rcv_nxt - tp->rcv_wnd >= tlen 2071 * th->th_seq - tp->rcv_nxt - tp->rcv_wnd >= 0 2072 * th->th_seq >= tp->rcv_nxt + tp->rcv_wnd 2073 */ 2074 tcpstat.tcps_rcvbyteafterwin += tlen; 2075 /* 2076 * If a new connection request is received 2077 * while in TIME_WAIT, drop the old connection 2078 * and start over if the sequence numbers 2079 * are above the previous ones. 2080 * 2081 * NOTE: We will checksum the packet again, and 2082 * so we need to put the header fields back into 2083 * network order! 2084 * XXX This kind of sucks, but we don't expect 2085 * XXX this to happen very often, so maybe it 2086 * XXX doesn't matter so much. 2087 */ 2088 if (tiflags & TH_SYN && 2089 tp->t_state == TCPS_TIME_WAIT && 2090 SEQ_GT(th->th_seq, tp->rcv_nxt)) { 2091 tp = tcp_close(tp); 2092 TCP_FIELDS_TO_NET(th); 2093 goto findpcb; 2094 } 2095 /* 2096 * If window is closed can only take segments at 2097 * window edge, and have to drop data and PUSH from 2098 * incoming segments. Continue processing, but 2099 * remember to ack. Otherwise, drop segment 2100 * and (if not RST) ack. 2101 */ 2102 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 2103 tp->t_flags |= TF_ACKNOW; 2104 tcpstat.tcps_rcvwinprobe++; 2105 } else 2106 goto dropafterack; 2107 } else 2108 tcpstat.tcps_rcvbyteafterwin += todrop; 2109 m_adj(m, -todrop); 2110 tlen -= todrop; 2111 tiflags &= ~(TH_PUSH|TH_FIN); 2112 } 2113 2114 /* 2115 * If last ACK falls within this segment's sequence numbers, 2116 * and the timestamp is newer, record it. 2117 */ 2118 if (opti.ts_present && TSTMP_GEQ(opti.ts_val, tp->ts_recent) && 2119 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 2120 SEQ_LT(tp->last_ack_sent, th->th_seq + tlen + 2121 ((tiflags & (TH_SYN|TH_FIN)) != 0))) { 2122 tp->ts_recent_age = tcp_now; 2123 tp->ts_recent = opti.ts_val; 2124 } 2125 2126 /* 2127 * If the RST bit is set examine the state: 2128 * SYN_RECEIVED STATE: 2129 * If passive open, return to LISTEN state. 2130 * If active open, inform user that connection was refused. 2131 * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES: 2132 * Inform user that connection was reset, and close tcb. 2133 * CLOSING, LAST_ACK, TIME_WAIT STATES 2134 * Close the tcb. 2135 */ 2136 if (tiflags & TH_RST) { 2137 if (th->th_seq != tp->last_ack_sent) 2138 goto dropafterack_ratelim; 2139 2140 switch (tp->t_state) { 2141 case TCPS_SYN_RECEIVED: 2142 so->so_error = ECONNREFUSED; 2143 goto close; 2144 2145 case TCPS_ESTABLISHED: 2146 case TCPS_FIN_WAIT_1: 2147 case TCPS_FIN_WAIT_2: 2148 case TCPS_CLOSE_WAIT: 2149 so->so_error = ECONNRESET; 2150 close: 2151 tp->t_state = TCPS_CLOSED; 2152 tcpstat.tcps_drops++; 2153 tp = tcp_close(tp); 2154 goto drop; 2155 2156 case TCPS_CLOSING: 2157 case TCPS_LAST_ACK: 2158 case TCPS_TIME_WAIT: 2159 tp = tcp_close(tp); 2160 goto drop; 2161 } 2162 } 2163 2164 /* 2165 * Since we've covered the SYN-SENT and SYN-RECEIVED states above 2166 * we must be in a synchronized state. RFC791 states (under RST 2167 * generation) that any unacceptable segment (an out-of-order SYN 2168 * qualifies) received in a synchronized state must elicit only an 2169 * empty acknowledgment segment ... and the connection remains in 2170 * the same state. 2171 */ 2172 if (tiflags & TH_SYN) { 2173 if (tp->rcv_nxt == th->th_seq) { 2174 tcp_respond(tp, m, m, th, (tcp_seq)0, th->th_ack - 1, 2175 TH_ACK); 2176 if (tcp_saveti) 2177 m_freem(tcp_saveti); 2178 return; 2179 } 2180 2181 goto dropafterack_ratelim; 2182 } 2183 2184 /* 2185 * If the ACK bit is off we drop the segment and return. 2186 */ 2187 if ((tiflags & TH_ACK) == 0) { 2188 if (tp->t_flags & TF_ACKNOW) 2189 goto dropafterack; 2190 else 2191 goto drop; 2192 } 2193 2194 /* 2195 * Ack processing. 2196 */ 2197 switch (tp->t_state) { 2198 2199 /* 2200 * In SYN_RECEIVED state if the ack ACKs our SYN then enter 2201 * ESTABLISHED state and continue processing, otherwise 2202 * send an RST. 2203 */ 2204 case TCPS_SYN_RECEIVED: 2205 if (SEQ_GT(tp->snd_una, th->th_ack) || 2206 SEQ_GT(th->th_ack, tp->snd_max)) 2207 goto dropwithreset; 2208 tcpstat.tcps_connects++; 2209 soisconnected(so); 2210 tcp_established(tp); 2211 /* Do window scaling? */ 2212 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2213 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2214 tp->snd_scale = tp->requested_s_scale; 2215 tp->rcv_scale = tp->request_r_scale; 2216 } 2217 TCP_REASS_LOCK(tp); 2218 (void) tcp_reass(tp, NULL, (struct mbuf *)0, &tlen); 2219 TCP_REASS_UNLOCK(tp); 2220 tp->snd_wl1 = th->th_seq - 1; 2221 /* fall into ... */ 2222 2223 /* 2224 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 2225 * ACKs. If the ack is in the range 2226 * tp->snd_una < th->th_ack <= tp->snd_max 2227 * then advance tp->snd_una to th->th_ack and drop 2228 * data from the retransmission queue. If this ACK reflects 2229 * more up to date window information we update our window information. 2230 */ 2231 case TCPS_ESTABLISHED: 2232 case TCPS_FIN_WAIT_1: 2233 case TCPS_FIN_WAIT_2: 2234 case TCPS_CLOSE_WAIT: 2235 case TCPS_CLOSING: 2236 case TCPS_LAST_ACK: 2237 case TCPS_TIME_WAIT: 2238 2239 if (SEQ_LEQ(th->th_ack, tp->snd_una)) { 2240 if (tlen == 0 && !dupseg && tiwin == tp->snd_wnd) { 2241 tcpstat.tcps_rcvdupack++; 2242 /* 2243 * If we have outstanding data (other than 2244 * a window probe), this is a completely 2245 * duplicate ack (ie, window info didn't 2246 * change), the ack is the biggest we've 2247 * seen and we've seen exactly our rexmt 2248 * threshhold of them, assume a packet 2249 * has been dropped and retransmit it. 2250 * Kludge snd_nxt & the congestion 2251 * window so we send only this one 2252 * packet. 2253 * 2254 * We know we're losing at the current 2255 * window size so do congestion avoidance 2256 * (set ssthresh to half the current window 2257 * and pull our congestion window back to 2258 * the new ssthresh). 2259 * 2260 * Dup acks mean that packets have left the 2261 * network (they're now cached at the receiver) 2262 * so bump cwnd by the amount in the receiver 2263 * to keep a constant cwnd packets in the 2264 * network. 2265 * 2266 * When using TCP ECN, notify the peer that 2267 * we reduced the cwnd. 2268 * 2269 * If we are using TCP/SACK, then enter 2270 * Fast Recovery if the receiver SACKs 2271 * data that is tcprexmtthresh * MSS 2272 * bytes past the last ACKed segment, 2273 * irrespective of the number of DupAcks. 2274 */ 2275 if (TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 || 2276 th->th_ack != tp->snd_una) 2277 tp->t_dupacks = 0; 2278 else if (tp->t_partialacks < 0 && 2279 (++tp->t_dupacks == tcprexmtthresh || 2280 TCP_FACK_FASTRECOV(tp))) { 2281 tcp_seq onxt; 2282 2283 if ((tcp_do_newreno || tcp_do_ecn) && 2284 SEQ_LT(th->th_ack, tp->snd_high)) { 2285 /* 2286 * False fast retransmit after 2287 * timeout. Do not enter fast 2288 * recovery. 2289 */ 2290 tp->t_dupacks = 0; 2291 break; 2292 } 2293 2294 onxt = tp->snd_nxt; 2295 tcp_congestion_exp(tp); 2296 tp->t_partialacks = 0; 2297 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2298 tp->t_rtttime = 0; 2299 if (TCP_SACK_ENABLED(tp)) { 2300 tp->t_dupacks = tcprexmtthresh; 2301 tp->sack_newdata = tp->snd_nxt; 2302 tp->snd_cwnd = tp->t_segsz; 2303 (void) tcp_output(tp); 2304 goto drop; 2305 } 2306 tp->snd_nxt = th->th_ack; 2307 tp->snd_cwnd = tp->t_segsz; 2308 (void) tcp_output(tp); 2309 tp->snd_cwnd = tp->snd_ssthresh + 2310 tp->t_segsz * tp->t_dupacks; 2311 if (SEQ_GT(onxt, tp->snd_nxt)) 2312 tp->snd_nxt = onxt; 2313 goto drop; 2314 } else if (tp->t_dupacks > tcprexmtthresh) { 2315 tp->snd_cwnd += tp->t_segsz; 2316 (void) tcp_output(tp); 2317 goto drop; 2318 } 2319 } else { 2320 /* 2321 * If the ack appears to be very old, only 2322 * allow data that is in-sequence. This 2323 * makes it somewhat more difficult to insert 2324 * forged data by guessing sequence numbers. 2325 * Sent an ack to try to update the send 2326 * sequence number on the other side. 2327 */ 2328 if (tlen && th->th_seq != tp->rcv_nxt && 2329 SEQ_LT(th->th_ack, 2330 tp->snd_una - tp->max_sndwnd)) 2331 goto dropafterack; 2332 } 2333 break; 2334 } 2335 /* 2336 * If the congestion window was inflated to account 2337 * for the other side's cached packets, retract it. 2338 */ 2339 if (TCP_SACK_ENABLED(tp)) 2340 tcp_sack_newack(tp, th); 2341 else if (tcp_do_newreno) 2342 tcp_newreno_newack(tp, th); 2343 else 2344 tcp_reno_newack(tp, th); 2345 if (SEQ_GT(th->th_ack, tp->snd_max)) { 2346 tcpstat.tcps_rcvacktoomuch++; 2347 goto dropafterack; 2348 } 2349 acked = th->th_ack - tp->snd_una; 2350 tcpstat.tcps_rcvackpack++; 2351 tcpstat.tcps_rcvackbyte += acked; 2352 2353 /* 2354 * If we have a timestamp reply, update smoothed 2355 * round trip time. If no timestamp is present but 2356 * transmit timer is running and timed sequence 2357 * number was acked, update smoothed round trip time. 2358 * Since we now have an rtt measurement, cancel the 2359 * timer backoff (cf., Phil Karn's retransmit alg.). 2360 * Recompute the initial retransmit timer. 2361 */ 2362 if (ts_rtt) 2363 tcp_xmit_timer(tp, ts_rtt); 2364 else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) 2365 tcp_xmit_timer(tp, tcp_now - tp->t_rtttime); 2366 2367 /* 2368 * If all outstanding data is acked, stop retransmit 2369 * timer and remember to restart (more output or persist). 2370 * If there is more data to be acked, restart retransmit 2371 * timer, using current (possibly backed-off) value. 2372 */ 2373 if (th->th_ack == tp->snd_max) { 2374 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2375 needoutput = 1; 2376 } else if (TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) 2377 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 2378 /* 2379 * When new data is acked, open the congestion window. 2380 * If the window gives us less than ssthresh packets 2381 * in flight, open exponentially (segsz per packet). 2382 * Otherwise open linearly: segsz per window 2383 * (segsz^2 / cwnd per packet). 2384 * 2385 * If we are still in fast recovery (meaning we are using 2386 * NewReno and we have only received partial acks), do not 2387 * inflate the window yet. 2388 */ 2389 if (tp->t_partialacks < 0) { 2390 u_int cw = tp->snd_cwnd; 2391 u_int incr = tp->t_segsz; 2392 2393 if (cw >= tp->snd_ssthresh) 2394 incr = incr * incr / cw; 2395 tp->snd_cwnd = min(cw + incr, 2396 TCP_MAXWIN << tp->snd_scale); 2397 } 2398 ND6_HINT(tp); 2399 if (acked > so->so_snd.sb_cc) { 2400 tp->snd_wnd -= so->so_snd.sb_cc; 2401 sbdrop(&so->so_snd, (int)so->so_snd.sb_cc); 2402 ourfinisacked = 1; 2403 } else { 2404 if (acked > (tp->t_lastoff - tp->t_inoff)) 2405 tp->t_lastm = NULL; 2406 sbdrop(&so->so_snd, acked); 2407 tp->t_lastoff -= acked; 2408 tp->snd_wnd -= acked; 2409 ourfinisacked = 0; 2410 } 2411 sowwakeup(so); 2412 2413 ICMP_CHECK(tp, th, acked); 2414 2415 tp->snd_una = th->th_ack; 2416 if (SEQ_GT(tp->snd_una, tp->snd_fack)) 2417 tp->snd_fack = tp->snd_una; 2418 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2419 tp->snd_nxt = tp->snd_una; 2420 if (SEQ_LT(tp->snd_high, tp->snd_una)) 2421 tp->snd_high = tp->snd_una; 2422 2423 switch (tp->t_state) { 2424 2425 /* 2426 * In FIN_WAIT_1 STATE in addition to the processing 2427 * for the ESTABLISHED state if our FIN is now acknowledged 2428 * then enter FIN_WAIT_2. 2429 */ 2430 case TCPS_FIN_WAIT_1: 2431 if (ourfinisacked) { 2432 /* 2433 * If we can't receive any more 2434 * data, then closing user can proceed. 2435 * Starting the timer is contrary to the 2436 * specification, but if we don't get a FIN 2437 * we'll hang forever. 2438 */ 2439 if (so->so_state & SS_CANTRCVMORE) { 2440 soisdisconnected(so); 2441 if (tcp_maxidle > 0) 2442 TCP_TIMER_ARM(tp, TCPT_2MSL, 2443 tcp_maxidle); 2444 } 2445 tp->t_state = TCPS_FIN_WAIT_2; 2446 } 2447 break; 2448 2449 /* 2450 * In CLOSING STATE in addition to the processing for 2451 * the ESTABLISHED state if the ACK acknowledges our FIN 2452 * then enter the TIME-WAIT state, otherwise ignore 2453 * the segment. 2454 */ 2455 case TCPS_CLOSING: 2456 if (ourfinisacked) { 2457 tp->t_state = TCPS_TIME_WAIT; 2458 tcp_canceltimers(tp); 2459 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 2460 soisdisconnected(so); 2461 } 2462 break; 2463 2464 /* 2465 * In LAST_ACK, we may still be waiting for data to drain 2466 * and/or to be acked, as well as for the ack of our FIN. 2467 * If our FIN is now acknowledged, delete the TCB, 2468 * enter the closed state and return. 2469 */ 2470 case TCPS_LAST_ACK: 2471 if (ourfinisacked) { 2472 tp = tcp_close(tp); 2473 goto drop; 2474 } 2475 break; 2476 2477 /* 2478 * In TIME_WAIT state the only thing that should arrive 2479 * is a retransmission of the remote FIN. Acknowledge 2480 * it and restart the finack timer. 2481 */ 2482 case TCPS_TIME_WAIT: 2483 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 2484 goto dropafterack; 2485 } 2486 } 2487 2488 step6: 2489 /* 2490 * Update window information. 2491 * Don't look at window if no ACK: TAC's send garbage on first SYN. 2492 */ 2493 if ((tiflags & TH_ACK) && (SEQ_LT(tp->snd_wl1, th->th_seq) || 2494 (tp->snd_wl1 == th->th_seq && (SEQ_LT(tp->snd_wl2, th->th_ack) || 2495 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))) { 2496 /* keep track of pure window updates */ 2497 if (tlen == 0 && 2498 tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) 2499 tcpstat.tcps_rcvwinupd++; 2500 tp->snd_wnd = tiwin; 2501 tp->snd_wl1 = th->th_seq; 2502 tp->snd_wl2 = th->th_ack; 2503 if (tp->snd_wnd > tp->max_sndwnd) 2504 tp->max_sndwnd = tp->snd_wnd; 2505 needoutput = 1; 2506 } 2507 2508 /* 2509 * Process segments with URG. 2510 */ 2511 if ((tiflags & TH_URG) && th->th_urp && 2512 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2513 /* 2514 * This is a kludge, but if we receive and accept 2515 * random urgent pointers, we'll crash in 2516 * soreceive. It's hard to imagine someone 2517 * actually wanting to send this much urgent data. 2518 */ 2519 if (th->th_urp + so->so_rcv.sb_cc > sb_max) { 2520 th->th_urp = 0; /* XXX */ 2521 tiflags &= ~TH_URG; /* XXX */ 2522 goto dodata; /* XXX */ 2523 } 2524 /* 2525 * If this segment advances the known urgent pointer, 2526 * then mark the data stream. This should not happen 2527 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 2528 * a FIN has been received from the remote side. 2529 * In these states we ignore the URG. 2530 * 2531 * According to RFC961 (Assigned Protocols), 2532 * the urgent pointer points to the last octet 2533 * of urgent data. We continue, however, 2534 * to consider it to indicate the first octet 2535 * of data past the urgent section as the original 2536 * spec states (in one of two places). 2537 */ 2538 if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) { 2539 tp->rcv_up = th->th_seq + th->th_urp; 2540 so->so_oobmark = so->so_rcv.sb_cc + 2541 (tp->rcv_up - tp->rcv_nxt) - 1; 2542 if (so->so_oobmark == 0) 2543 so->so_state |= SS_RCVATMARK; 2544 sohasoutofband(so); 2545 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); 2546 } 2547 /* 2548 * Remove out of band data so doesn't get presented to user. 2549 * This can happen independent of advancing the URG pointer, 2550 * but if two URG's are pending at once, some out-of-band 2551 * data may creep in... ick. 2552 */ 2553 if (th->th_urp <= (u_int16_t) tlen 2554 #ifdef SO_OOBINLINE 2555 && (so->so_options & SO_OOBINLINE) == 0 2556 #endif 2557 ) 2558 tcp_pulloutofband(so, th, m, hdroptlen); 2559 } else 2560 /* 2561 * If no out of band data is expected, 2562 * pull receive urgent pointer along 2563 * with the receive window. 2564 */ 2565 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) 2566 tp->rcv_up = tp->rcv_nxt; 2567 dodata: /* XXX */ 2568 2569 /* 2570 * Process the segment text, merging it into the TCP sequencing queue, 2571 * and arranging for acknowledgement of receipt if necessary. 2572 * This process logically involves adjusting tp->rcv_wnd as data 2573 * is presented to the user (this happens in tcp_usrreq.c, 2574 * case PRU_RCVD). If a FIN has already been received on this 2575 * connection then we just ignore the text. 2576 */ 2577 if ((tlen || (tiflags & TH_FIN)) && 2578 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2579 /* 2580 * Insert segment ti into reassembly queue of tcp with 2581 * control block tp. Return TH_FIN if reassembly now includes 2582 * a segment with FIN. The macro form does the common case 2583 * inline (segment is the next to be received on an 2584 * established connection, and the queue is empty), 2585 * avoiding linkage into and removal from the queue and 2586 * repetition of various conversions. 2587 * Set DELACK for segments received in order, but ack 2588 * immediately when segments are out of order 2589 * (so fast retransmit can work). 2590 */ 2591 /* NOTE: this was TCP_REASS() macro, but used only once */ 2592 TCP_REASS_LOCK(tp); 2593 if (th->th_seq == tp->rcv_nxt && 2594 TAILQ_FIRST(&tp->segq) == NULL && 2595 tp->t_state == TCPS_ESTABLISHED) { 2596 TCP_SETUP_ACK(tp, th); 2597 tp->rcv_nxt += tlen; 2598 tiflags = th->th_flags & TH_FIN; 2599 tcpstat.tcps_rcvpack++; 2600 tcpstat.tcps_rcvbyte += tlen; 2601 ND6_HINT(tp); 2602 if (so->so_state & SS_CANTRCVMORE) 2603 m_freem(m); 2604 else { 2605 m_adj(m, hdroptlen); 2606 sbappendstream(&(so)->so_rcv, m); 2607 } 2608 sorwakeup(so); 2609 } else { 2610 m_adj(m, hdroptlen); 2611 tiflags = tcp_reass(tp, th, m, &tlen); 2612 tp->t_flags |= TF_ACKNOW; 2613 } 2614 TCP_REASS_UNLOCK(tp); 2615 2616 /* 2617 * Note the amount of data that peer has sent into 2618 * our window, in order to estimate the sender's 2619 * buffer size. 2620 */ 2621 len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); 2622 } else { 2623 m_freem(m); 2624 m = NULL; 2625 tiflags &= ~TH_FIN; 2626 } 2627 2628 /* 2629 * If FIN is received ACK the FIN and let the user know 2630 * that the connection is closing. Ignore a FIN received before 2631 * the connection is fully established. 2632 */ 2633 if ((tiflags & TH_FIN) && TCPS_HAVEESTABLISHED(tp->t_state)) { 2634 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2635 socantrcvmore(so); 2636 tp->t_flags |= TF_ACKNOW; 2637 tp->rcv_nxt++; 2638 } 2639 switch (tp->t_state) { 2640 2641 /* 2642 * In ESTABLISHED STATE enter the CLOSE_WAIT state. 2643 */ 2644 case TCPS_ESTABLISHED: 2645 tp->t_state = TCPS_CLOSE_WAIT; 2646 break; 2647 2648 /* 2649 * If still in FIN_WAIT_1 STATE FIN has not been acked so 2650 * enter the CLOSING state. 2651 */ 2652 case TCPS_FIN_WAIT_1: 2653 tp->t_state = TCPS_CLOSING; 2654 break; 2655 2656 /* 2657 * In FIN_WAIT_2 state enter the TIME_WAIT state, 2658 * starting the time-wait timer, turning off the other 2659 * standard timers. 2660 */ 2661 case TCPS_FIN_WAIT_2: 2662 tp->t_state = TCPS_TIME_WAIT; 2663 tcp_canceltimers(tp); 2664 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 2665 soisdisconnected(so); 2666 break; 2667 2668 /* 2669 * In TIME_WAIT state restart the 2 MSL time_wait timer. 2670 */ 2671 case TCPS_TIME_WAIT: 2672 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 2673 break; 2674 } 2675 } 2676 #ifdef TCP_DEBUG 2677 if (so->so_options & SO_DEBUG) 2678 tcp_trace(TA_INPUT, ostate, tp, tcp_saveti, 0); 2679 #endif 2680 2681 /* 2682 * Return any desired output. 2683 */ 2684 if (needoutput || (tp->t_flags & TF_ACKNOW)) { 2685 (void) tcp_output(tp); 2686 } 2687 if (tcp_saveti) 2688 m_freem(tcp_saveti); 2689 return; 2690 2691 badsyn: 2692 /* 2693 * Received a bad SYN. Increment counters and dropwithreset. 2694 */ 2695 tcpstat.tcps_badsyn++; 2696 tp = NULL; 2697 goto dropwithreset; 2698 2699 dropafterack: 2700 /* 2701 * Generate an ACK dropping incoming segment if it occupies 2702 * sequence space, where the ACK reflects our state. 2703 */ 2704 if (tiflags & TH_RST) 2705 goto drop; 2706 goto dropafterack2; 2707 2708 dropafterack_ratelim: 2709 /* 2710 * We may want to rate-limit ACKs against SYN/RST attack. 2711 */ 2712 if (ppsratecheck(&tcp_ackdrop_ppslim_last, &tcp_ackdrop_ppslim_count, 2713 tcp_ackdrop_ppslim) == 0) { 2714 /* XXX stat */ 2715 goto drop; 2716 } 2717 /* ...fall into dropafterack2... */ 2718 2719 dropafterack2: 2720 m_freem(m); 2721 tp->t_flags |= TF_ACKNOW; 2722 (void) tcp_output(tp); 2723 if (tcp_saveti) 2724 m_freem(tcp_saveti); 2725 return; 2726 2727 dropwithreset_ratelim: 2728 /* 2729 * We may want to rate-limit RSTs in certain situations, 2730 * particularly if we are sending an RST in response to 2731 * an attempt to connect to or otherwise communicate with 2732 * a port for which we have no socket. 2733 */ 2734 if (ppsratecheck(&tcp_rst_ppslim_last, &tcp_rst_ppslim_count, 2735 tcp_rst_ppslim) == 0) { 2736 /* XXX stat */ 2737 goto drop; 2738 } 2739 /* ...fall into dropwithreset... */ 2740 2741 dropwithreset: 2742 /* 2743 * Generate a RST, dropping incoming segment. 2744 * Make ACK acceptable to originator of segment. 2745 */ 2746 if (tiflags & TH_RST) 2747 goto drop; 2748 2749 switch (af) { 2750 #ifdef INET6 2751 case AF_INET6: 2752 /* For following calls to tcp_respond */ 2753 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) 2754 goto drop; 2755 break; 2756 #endif /* INET6 */ 2757 case AF_INET: 2758 if (IN_MULTICAST(ip->ip_dst.s_addr) || 2759 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 2760 goto drop; 2761 } 2762 2763 if (tiflags & TH_ACK) 2764 (void)tcp_respond(tp, m, m, th, (tcp_seq)0, th->th_ack, TH_RST); 2765 else { 2766 if (tiflags & TH_SYN) 2767 tlen++; 2768 (void)tcp_respond(tp, m, m, th, th->th_seq + tlen, (tcp_seq)0, 2769 TH_RST|TH_ACK); 2770 } 2771 if (tcp_saveti) 2772 m_freem(tcp_saveti); 2773 return; 2774 2775 badcsum: 2776 drop: 2777 /* 2778 * Drop space held by incoming segment and return. 2779 */ 2780 if (tp) { 2781 if (tp->t_inpcb) 2782 so = tp->t_inpcb->inp_socket; 2783 #ifdef INET6 2784 else if (tp->t_in6pcb) 2785 so = tp->t_in6pcb->in6p_socket; 2786 #endif 2787 else 2788 so = NULL; 2789 #ifdef TCP_DEBUG 2790 if (so && (so->so_options & SO_DEBUG) != 0) 2791 tcp_trace(TA_DROP, ostate, tp, tcp_saveti, 0); 2792 #endif 2793 } 2794 if (tcp_saveti) 2795 m_freem(tcp_saveti); 2796 m_freem(m); 2797 return; 2798 } 2799 2800 #ifdef TCP_SIGNATURE 2801 int 2802 tcp_signature_apply(void *fstate, caddr_t data, u_int len) 2803 { 2804 2805 MD5Update(fstate, (u_char *)data, len); 2806 return (0); 2807 } 2808 2809 struct secasvar * 2810 tcp_signature_getsav(struct mbuf *m, struct tcphdr *th) 2811 { 2812 struct secasvar *sav; 2813 #ifdef FAST_IPSEC 2814 union sockaddr_union dst; 2815 #endif 2816 struct ip *ip; 2817 struct ip6_hdr *ip6; 2818 2819 ip = mtod(m, struct ip *); 2820 switch (ip->ip_v) { 2821 case 4: 2822 ip = mtod(m, struct ip *); 2823 ip6 = NULL; 2824 break; 2825 case 6: 2826 ip = NULL; 2827 ip6 = mtod(m, struct ip6_hdr *); 2828 break; 2829 default: 2830 return (NULL); 2831 } 2832 2833 #ifdef FAST_IPSEC 2834 /* Extract the destination from the IP header in the mbuf. */ 2835 bzero(&dst, sizeof(union sockaddr_union)); 2836 dst.sa.sa_len = sizeof(struct sockaddr_in); 2837 dst.sa.sa_family = AF_INET; 2838 dst.sin.sin_addr = ip->ip_dst; 2839 2840 /* 2841 * Look up an SADB entry which matches the address of the peer. 2842 */ 2843 sav = KEY_ALLOCSA(&dst, IPPROTO_TCP, htonl(TCP_SIG_SPI)); 2844 #else 2845 if (ip) 2846 sav = key_allocsa(AF_INET, (caddr_t)&ip->ip_src, 2847 (caddr_t)&ip->ip_dst, IPPROTO_TCP, 2848 htonl(TCP_SIG_SPI), 0, 0); 2849 else 2850 sav = key_allocsa(AF_INET6, (caddr_t)&ip6->ip6_src, 2851 (caddr_t)&ip6->ip6_dst, IPPROTO_TCP, 2852 htonl(TCP_SIG_SPI), 0, 0); 2853 #endif 2854 2855 return (sav); /* freesav must be performed by caller */ 2856 } 2857 2858 int 2859 tcp_signature(struct mbuf *m, struct tcphdr *th, int thoff, 2860 struct secasvar *sav, char *sig) 2861 { 2862 MD5_CTX ctx; 2863 struct ip *ip; 2864 struct ipovly *ipovly; 2865 struct ip6_hdr *ip6; 2866 struct ippseudo ippseudo; 2867 struct ip6_hdr_pseudo ip6pseudo; 2868 struct tcphdr th0; 2869 int l, tcphdrlen; 2870 2871 if (sav == NULL) 2872 return (-1); 2873 2874 tcphdrlen = th->th_off * 4; 2875 2876 switch (mtod(m, struct ip *)->ip_v) { 2877 case 4: 2878 ip = mtod(m, struct ip *); 2879 ip6 = NULL; 2880 break; 2881 case 6: 2882 ip = NULL; 2883 ip6 = mtod(m, struct ip6_hdr *); 2884 break; 2885 default: 2886 return (-1); 2887 } 2888 2889 MD5Init(&ctx); 2890 2891 if (ip) { 2892 memset(&ippseudo, 0, sizeof(ippseudo)); 2893 ipovly = (struct ipovly *)ip; 2894 ippseudo.ippseudo_src = ipovly->ih_src; 2895 ippseudo.ippseudo_dst = ipovly->ih_dst; 2896 ippseudo.ippseudo_pad = 0; 2897 ippseudo.ippseudo_p = IPPROTO_TCP; 2898 ippseudo.ippseudo_len = htons(m->m_pkthdr.len - thoff); 2899 MD5Update(&ctx, (char *)&ippseudo, sizeof(ippseudo)); 2900 } else { 2901 memset(&ip6pseudo, 0, sizeof(ip6pseudo)); 2902 ip6pseudo.ip6ph_src = ip6->ip6_src; 2903 in6_clearscope(&ip6pseudo.ip6ph_src); 2904 ip6pseudo.ip6ph_dst = ip6->ip6_dst; 2905 in6_clearscope(&ip6pseudo.ip6ph_dst); 2906 ip6pseudo.ip6ph_len = htons(m->m_pkthdr.len - thoff); 2907 ip6pseudo.ip6ph_nxt = IPPROTO_TCP; 2908 MD5Update(&ctx, (char *)&ip6pseudo, sizeof(ip6pseudo)); 2909 } 2910 2911 th0 = *th; 2912 th0.th_sum = 0; 2913 MD5Update(&ctx, (char *)&th0, sizeof(th0)); 2914 2915 l = m->m_pkthdr.len - thoff - tcphdrlen; 2916 if (l > 0) 2917 m_apply(m, thoff + tcphdrlen, 2918 m->m_pkthdr.len - thoff - tcphdrlen, 2919 tcp_signature_apply, &ctx); 2920 2921 MD5Update(&ctx, _KEYBUF(sav->key_auth), _KEYLEN(sav->key_auth)); 2922 MD5Final(sig, &ctx); 2923 2924 return (0); 2925 } 2926 #endif 2927 2928 int 2929 tcp_dooptions(struct tcpcb *tp, u_char *cp, int cnt, struct tcphdr *th, 2930 struct mbuf *m, int toff, struct tcp_opt_info *oi) 2931 { 2932 u_int16_t mss; 2933 int opt, optlen = 0; 2934 #ifdef TCP_SIGNATURE 2935 caddr_t sigp = NULL; 2936 char sigbuf[TCP_SIGLEN]; 2937 struct secasvar *sav = NULL; 2938 #endif 2939 2940 for (; cp && cnt > 0; cnt -= optlen, cp += optlen) { 2941 opt = cp[0]; 2942 if (opt == TCPOPT_EOL) 2943 break; 2944 if (opt == TCPOPT_NOP) 2945 optlen = 1; 2946 else { 2947 if (cnt < 2) 2948 break; 2949 optlen = cp[1]; 2950 if (optlen < 2 || optlen > cnt) 2951 break; 2952 } 2953 switch (opt) { 2954 2955 default: 2956 continue; 2957 2958 case TCPOPT_MAXSEG: 2959 if (optlen != TCPOLEN_MAXSEG) 2960 continue; 2961 if (!(th->th_flags & TH_SYN)) 2962 continue; 2963 if (TCPS_HAVERCVDSYN(tp->t_state)) 2964 continue; 2965 bcopy(cp + 2, &mss, sizeof(mss)); 2966 oi->maxseg = ntohs(mss); 2967 break; 2968 2969 case TCPOPT_WINDOW: 2970 if (optlen != TCPOLEN_WINDOW) 2971 continue; 2972 if (!(th->th_flags & TH_SYN)) 2973 continue; 2974 if (TCPS_HAVERCVDSYN(tp->t_state)) 2975 continue; 2976 tp->t_flags |= TF_RCVD_SCALE; 2977 tp->requested_s_scale = cp[2]; 2978 if (tp->requested_s_scale > TCP_MAX_WINSHIFT) { 2979 #if 0 /*XXX*/ 2980 char *p; 2981 2982 if (ip) 2983 p = ntohl(ip->ip_src); 2984 #ifdef INET6 2985 else if (ip6) 2986 p = ip6_sprintf(&ip6->ip6_src); 2987 #endif 2988 else 2989 p = "(unknown)"; 2990 log(LOG_ERR, "TCP: invalid wscale %d from %s, " 2991 "assuming %d\n", 2992 tp->requested_s_scale, p, 2993 TCP_MAX_WINSHIFT); 2994 #else 2995 log(LOG_ERR, "TCP: invalid wscale %d, " 2996 "assuming %d\n", 2997 tp->requested_s_scale, 2998 TCP_MAX_WINSHIFT); 2999 #endif 3000 tp->requested_s_scale = TCP_MAX_WINSHIFT; 3001 } 3002 break; 3003 3004 case TCPOPT_TIMESTAMP: 3005 if (optlen != TCPOLEN_TIMESTAMP) 3006 continue; 3007 oi->ts_present = 1; 3008 bcopy(cp + 2, &oi->ts_val, sizeof(oi->ts_val)); 3009 NTOHL(oi->ts_val); 3010 bcopy(cp + 6, &oi->ts_ecr, sizeof(oi->ts_ecr)); 3011 NTOHL(oi->ts_ecr); 3012 3013 if (!(th->th_flags & TH_SYN)) 3014 continue; 3015 if (TCPS_HAVERCVDSYN(tp->t_state)) 3016 continue; 3017 /* 3018 * A timestamp received in a SYN makes 3019 * it ok to send timestamp requests and replies. 3020 */ 3021 tp->t_flags |= TF_RCVD_TSTMP; 3022 tp->ts_recent = oi->ts_val; 3023 tp->ts_recent_age = tcp_now; 3024 break; 3025 3026 case TCPOPT_SACK_PERMITTED: 3027 if (optlen != TCPOLEN_SACK_PERMITTED) 3028 continue; 3029 if (!(th->th_flags & TH_SYN)) 3030 continue; 3031 if (TCPS_HAVERCVDSYN(tp->t_state)) 3032 continue; 3033 if (tcp_do_sack) { 3034 tp->t_flags |= TF_SACK_PERMIT; 3035 tp->t_flags |= TF_WILL_SACK; 3036 } 3037 break; 3038 3039 case TCPOPT_SACK: 3040 tcp_sack_option(tp, th, cp, optlen); 3041 break; 3042 #ifdef TCP_SIGNATURE 3043 case TCPOPT_SIGNATURE: 3044 if (optlen != TCPOLEN_SIGNATURE) 3045 continue; 3046 if (sigp && bcmp(sigp, cp + 2, TCP_SIGLEN)) 3047 return (-1); 3048 3049 sigp = sigbuf; 3050 memcpy(sigbuf, cp + 2, TCP_SIGLEN); 3051 memset(cp + 2, 0, TCP_SIGLEN); 3052 tp->t_flags |= TF_SIGNATURE; 3053 break; 3054 #endif 3055 } 3056 } 3057 3058 #ifdef TCP_SIGNATURE 3059 if (tp->t_flags & TF_SIGNATURE) { 3060 3061 sav = tcp_signature_getsav(m, th); 3062 3063 if (sav == NULL && tp->t_state == TCPS_LISTEN) 3064 return (-1); 3065 } 3066 3067 if ((sigp ? TF_SIGNATURE : 0) ^ (tp->t_flags & TF_SIGNATURE)) { 3068 if (sav == NULL) 3069 return (-1); 3070 #ifdef FAST_IPSEC 3071 KEY_FREESAV(&sav); 3072 #else 3073 key_freesav(sav); 3074 #endif 3075 return (-1); 3076 } 3077 3078 if (sigp) { 3079 char sig[TCP_SIGLEN]; 3080 3081 TCP_FIELDS_TO_NET(th); 3082 if (tcp_signature(m, th, toff, sav, sig) < 0) { 3083 TCP_FIELDS_TO_HOST(th); 3084 if (sav == NULL) 3085 return (-1); 3086 #ifdef FAST_IPSEC 3087 KEY_FREESAV(&sav); 3088 #else 3089 key_freesav(sav); 3090 #endif 3091 return (-1); 3092 } 3093 TCP_FIELDS_TO_HOST(th); 3094 3095 if (bcmp(sig, sigp, TCP_SIGLEN)) { 3096 tcpstat.tcps_badsig++; 3097 if (sav == NULL) 3098 return (-1); 3099 #ifdef FAST_IPSEC 3100 KEY_FREESAV(&sav); 3101 #else 3102 key_freesav(sav); 3103 #endif 3104 return (-1); 3105 } else 3106 tcpstat.tcps_goodsig++; 3107 3108 key_sa_recordxfer(sav, m); 3109 #ifdef FAST_IPSEC 3110 KEY_FREESAV(&sav); 3111 #else 3112 key_freesav(sav); 3113 #endif 3114 } 3115 #endif 3116 3117 return (0); 3118 } 3119 3120 /* 3121 * Pull out of band byte out of a segment so 3122 * it doesn't appear in the user's data queue. 3123 * It is still reflected in the segment length for 3124 * sequencing purposes. 3125 */ 3126 void 3127 tcp_pulloutofband(struct socket *so, struct tcphdr *th, 3128 struct mbuf *m, int off) 3129 { 3130 int cnt = off + th->th_urp - 1; 3131 3132 while (cnt >= 0) { 3133 if (m->m_len > cnt) { 3134 char *cp = mtod(m, caddr_t) + cnt; 3135 struct tcpcb *tp = sototcpcb(so); 3136 3137 tp->t_iobc = *cp; 3138 tp->t_oobflags |= TCPOOB_HAVEDATA; 3139 bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); 3140 m->m_len--; 3141 return; 3142 } 3143 cnt -= m->m_len; 3144 m = m->m_next; 3145 if (m == 0) 3146 break; 3147 } 3148 panic("tcp_pulloutofband"); 3149 } 3150 3151 /* 3152 * Collect new round-trip time estimate 3153 * and update averages and current timeout. 3154 */ 3155 void 3156 tcp_xmit_timer(struct tcpcb *tp, uint32_t rtt) 3157 { 3158 int32_t delta; 3159 3160 tcpstat.tcps_rttupdated++; 3161 if (tp->t_srtt != 0) { 3162 /* 3163 * srtt is stored as fixed point with 3 bits after the 3164 * binary point (i.e., scaled by 8). The following magic 3165 * is equivalent to the smoothing algorithm in rfc793 with 3166 * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed 3167 * point). Adjust rtt to origin 0. 3168 */ 3169 delta = (rtt << 2) - (tp->t_srtt >> TCP_RTT_SHIFT); 3170 if ((tp->t_srtt += delta) <= 0) 3171 tp->t_srtt = 1 << 2; 3172 /* 3173 * We accumulate a smoothed rtt variance (actually, a 3174 * smoothed mean difference), then set the retransmit 3175 * timer to smoothed rtt + 4 times the smoothed variance. 3176 * rttvar is stored as fixed point with 2 bits after the 3177 * binary point (scaled by 4). The following is 3178 * equivalent to rfc793 smoothing with an alpha of .75 3179 * (rttvar = rttvar*3/4 + |delta| / 4). This replaces 3180 * rfc793's wired-in beta. 3181 */ 3182 if (delta < 0) 3183 delta = -delta; 3184 delta -= (tp->t_rttvar >> TCP_RTTVAR_SHIFT); 3185 if ((tp->t_rttvar += delta) <= 0) 3186 tp->t_rttvar = 1 << 2; 3187 } else { 3188 /* 3189 * No rtt measurement yet - use the unsmoothed rtt. 3190 * Set the variance to half the rtt (so our first 3191 * retransmit happens at 3*rtt). 3192 */ 3193 tp->t_srtt = rtt << (TCP_RTT_SHIFT + 2); 3194 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT + 2 - 1); 3195 } 3196 tp->t_rtttime = 0; 3197 tp->t_rxtshift = 0; 3198 3199 /* 3200 * the retransmit should happen at rtt + 4 * rttvar. 3201 * Because of the way we do the smoothing, srtt and rttvar 3202 * will each average +1/2 tick of bias. When we compute 3203 * the retransmit timer, we want 1/2 tick of rounding and 3204 * 1 extra tick because of +-1/2 tick uncertainty in the 3205 * firing of the timer. The bias will give us exactly the 3206 * 1.5 tick we need. But, because the bias is 3207 * statistical, we have to test that we don't drop below 3208 * the minimum feasible timer (which is 2 ticks). 3209 */ 3210 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), 3211 max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX); 3212 3213 /* 3214 * We received an ack for a packet that wasn't retransmitted; 3215 * it is probably safe to discard any error indications we've 3216 * received recently. This isn't quite right, but close enough 3217 * for now (a route might have failed after we sent a segment, 3218 * and the return path might not be symmetrical). 3219 */ 3220 tp->t_softerror = 0; 3221 } 3222 3223 void 3224 tcp_reno_newack(struct tcpcb *tp, struct tcphdr *th) 3225 { 3226 if (tp->t_partialacks < 0) { 3227 /* 3228 * We were not in fast recovery. Reset the duplicate ack 3229 * counter. 3230 */ 3231 tp->t_dupacks = 0; 3232 } else { 3233 /* 3234 * Clamp the congestion window to the crossover point and 3235 * exit fast recovery. 3236 */ 3237 if (tp->snd_cwnd > tp->snd_ssthresh) 3238 tp->snd_cwnd = tp->snd_ssthresh; 3239 tp->t_partialacks = -1; 3240 tp->t_dupacks = 0; 3241 } 3242 } 3243 3244 /* 3245 * Implement the NewReno response to a new ack, checking for partial acks in 3246 * fast recovery. 3247 */ 3248 void 3249 tcp_newreno_newack(struct tcpcb *tp, struct tcphdr *th) 3250 { 3251 if (tp->t_partialacks < 0) { 3252 /* 3253 * We were not in fast recovery. Reset the duplicate ack 3254 * counter. 3255 */ 3256 tp->t_dupacks = 0; 3257 } else if (SEQ_LT(th->th_ack, tp->snd_recover)) { 3258 /* 3259 * This is a partial ack. Retransmit the first unacknowledged 3260 * segment and deflate the congestion window by the amount of 3261 * acknowledged data. Do not exit fast recovery. 3262 */ 3263 tcp_seq onxt = tp->snd_nxt; 3264 u_long ocwnd = tp->snd_cwnd; 3265 3266 /* 3267 * snd_una has not yet been updated and the socket's send 3268 * buffer has not yet drained off the ACK'd data, so we 3269 * have to leave snd_una as it was to get the correct data 3270 * offset in tcp_output(). 3271 */ 3272 if (++tp->t_partialacks == 1) 3273 TCP_TIMER_DISARM(tp, TCPT_REXMT); 3274 tp->t_rtttime = 0; 3275 tp->snd_nxt = th->th_ack; 3276 /* 3277 * Set snd_cwnd to one segment beyond ACK'd offset. snd_una 3278 * is not yet updated when we're called. 3279 */ 3280 tp->snd_cwnd = tp->t_segsz + (th->th_ack - tp->snd_una); 3281 (void) tcp_output(tp); 3282 tp->snd_cwnd = ocwnd; 3283 if (SEQ_GT(onxt, tp->snd_nxt)) 3284 tp->snd_nxt = onxt; 3285 /* 3286 * Partial window deflation. Relies on fact that tp->snd_una 3287 * not updated yet. 3288 */ 3289 tp->snd_cwnd -= (th->th_ack - tp->snd_una - tp->t_segsz); 3290 } else { 3291 /* 3292 * Complete ack. Inflate the congestion window to ssthresh 3293 * and exit fast recovery. 3294 * 3295 * Window inflation should have left us with approx. 3296 * snd_ssthresh outstanding data. But in case we 3297 * would be inclined to send a burst, better to do 3298 * it via the slow start mechanism. 3299 */ 3300 if (SEQ_SUB(tp->snd_max, th->th_ack) < tp->snd_ssthresh) 3301 tp->snd_cwnd = SEQ_SUB(tp->snd_max, th->th_ack) 3302 + tp->t_segsz; 3303 else 3304 tp->snd_cwnd = tp->snd_ssthresh; 3305 tp->t_partialacks = -1; 3306 tp->t_dupacks = 0; 3307 } 3308 } 3309 3310 3311 /* 3312 * TCP compressed state engine. Currently used to hold compressed 3313 * state for SYN_RECEIVED. 3314 */ 3315 3316 u_long syn_cache_count; 3317 u_int32_t syn_hash1, syn_hash2; 3318 3319 #define SYN_HASH(sa, sp, dp) \ 3320 ((((sa)->s_addr^syn_hash1)*(((((u_int32_t)(dp))<<16) + \ 3321 ((u_int32_t)(sp)))^syn_hash2))) 3322 #ifndef INET6 3323 #define SYN_HASHALL(hash, src, dst) \ 3324 do { \ 3325 hash = SYN_HASH(&((const struct sockaddr_in *)(src))->sin_addr, \ 3326 ((const struct sockaddr_in *)(src))->sin_port, \ 3327 ((const struct sockaddr_in *)(dst))->sin_port); \ 3328 } while (/*CONSTCOND*/ 0) 3329 #else 3330 #define SYN_HASH6(sa, sp, dp) \ 3331 ((((sa)->s6_addr32[0] ^ (sa)->s6_addr32[3] ^ syn_hash1) * \ 3332 (((((u_int32_t)(dp))<<16) + ((u_int32_t)(sp)))^syn_hash2)) \ 3333 & 0x7fffffff) 3334 3335 #define SYN_HASHALL(hash, src, dst) \ 3336 do { \ 3337 switch ((src)->sa_family) { \ 3338 case AF_INET: \ 3339 hash = SYN_HASH(&((const struct sockaddr_in *)(src))->sin_addr, \ 3340 ((const struct sockaddr_in *)(src))->sin_port, \ 3341 ((const struct sockaddr_in *)(dst))->sin_port); \ 3342 break; \ 3343 case AF_INET6: \ 3344 hash = SYN_HASH6(&((const struct sockaddr_in6 *)(src))->sin6_addr, \ 3345 ((const struct sockaddr_in6 *)(src))->sin6_port, \ 3346 ((const struct sockaddr_in6 *)(dst))->sin6_port); \ 3347 break; \ 3348 default: \ 3349 hash = 0; \ 3350 } \ 3351 } while (/*CONSTCOND*/0) 3352 #endif /* INET6 */ 3353 3354 #define SYN_CACHE_RM(sc) \ 3355 do { \ 3356 TAILQ_REMOVE(&tcp_syn_cache[(sc)->sc_bucketidx].sch_bucket, \ 3357 (sc), sc_bucketq); \ 3358 (sc)->sc_tp = NULL; \ 3359 LIST_REMOVE((sc), sc_tpq); \ 3360 tcp_syn_cache[(sc)->sc_bucketidx].sch_length--; \ 3361 callout_stop(&(sc)->sc_timer); \ 3362 syn_cache_count--; \ 3363 } while (/*CONSTCOND*/0) 3364 3365 #define SYN_CACHE_PUT(sc) \ 3366 do { \ 3367 if ((sc)->sc_ipopts) \ 3368 (void) m_free((sc)->sc_ipopts); \ 3369 if ((sc)->sc_route4.ro_rt != NULL) \ 3370 RTFREE((sc)->sc_route4.ro_rt); \ 3371 if (callout_invoking(&(sc)->sc_timer)) \ 3372 (sc)->sc_flags |= SCF_DEAD; \ 3373 else \ 3374 pool_put(&syn_cache_pool, (sc)); \ 3375 } while (/*CONSTCOND*/0) 3376 3377 POOL_INIT(syn_cache_pool, sizeof(struct syn_cache), 0, 0, 0, "synpl", NULL); 3378 3379 /* 3380 * We don't estimate RTT with SYNs, so each packet starts with the default 3381 * RTT and each timer step has a fixed timeout value. 3382 */ 3383 #define SYN_CACHE_TIMER_ARM(sc) \ 3384 do { \ 3385 TCPT_RANGESET((sc)->sc_rxtcur, \ 3386 TCPTV_SRTTDFLT * tcp_backoff[(sc)->sc_rxtshift], TCPTV_MIN, \ 3387 TCPTV_REXMTMAX); \ 3388 callout_reset(&(sc)->sc_timer, \ 3389 (sc)->sc_rxtcur * (hz / PR_SLOWHZ), syn_cache_timer, (sc)); \ 3390 } while (/*CONSTCOND*/0) 3391 3392 #define SYN_CACHE_TIMESTAMP(sc) (tcp_now - (sc)->sc_timebase) 3393 3394 void 3395 syn_cache_init(void) 3396 { 3397 int i; 3398 3399 /* Initialize the hash buckets. */ 3400 for (i = 0; i < tcp_syn_cache_size; i++) 3401 TAILQ_INIT(&tcp_syn_cache[i].sch_bucket); 3402 } 3403 3404 void 3405 syn_cache_insert(struct syn_cache *sc, struct tcpcb *tp) 3406 { 3407 struct syn_cache_head *scp; 3408 struct syn_cache *sc2; 3409 int s; 3410 3411 /* 3412 * If there are no entries in the hash table, reinitialize 3413 * the hash secrets. 3414 */ 3415 if (syn_cache_count == 0) { 3416 syn_hash1 = arc4random(); 3417 syn_hash2 = arc4random(); 3418 } 3419 3420 SYN_HASHALL(sc->sc_hash, &sc->sc_src.sa, &sc->sc_dst.sa); 3421 sc->sc_bucketidx = sc->sc_hash % tcp_syn_cache_size; 3422 scp = &tcp_syn_cache[sc->sc_bucketidx]; 3423 3424 /* 3425 * Make sure that we don't overflow the per-bucket 3426 * limit or the total cache size limit. 3427 */ 3428 s = splsoftnet(); 3429 if (scp->sch_length >= tcp_syn_bucket_limit) { 3430 tcpstat.tcps_sc_bucketoverflow++; 3431 /* 3432 * The bucket is full. Toss the oldest element in the 3433 * bucket. This will be the first entry in the bucket. 3434 */ 3435 sc2 = TAILQ_FIRST(&scp->sch_bucket); 3436 #ifdef DIAGNOSTIC 3437 /* 3438 * This should never happen; we should always find an 3439 * entry in our bucket. 3440 */ 3441 if (sc2 == NULL) 3442 panic("syn_cache_insert: bucketoverflow: impossible"); 3443 #endif 3444 SYN_CACHE_RM(sc2); 3445 SYN_CACHE_PUT(sc2); 3446 } else if (syn_cache_count >= tcp_syn_cache_limit) { 3447 struct syn_cache_head *scp2, *sce; 3448 3449 tcpstat.tcps_sc_overflowed++; 3450 /* 3451 * The cache is full. Toss the oldest entry in the 3452 * first non-empty bucket we can find. 3453 * 3454 * XXX We would really like to toss the oldest 3455 * entry in the cache, but we hope that this 3456 * condition doesn't happen very often. 3457 */ 3458 scp2 = scp; 3459 if (TAILQ_EMPTY(&scp2->sch_bucket)) { 3460 sce = &tcp_syn_cache[tcp_syn_cache_size]; 3461 for (++scp2; scp2 != scp; scp2++) { 3462 if (scp2 >= sce) 3463 scp2 = &tcp_syn_cache[0]; 3464 if (! TAILQ_EMPTY(&scp2->sch_bucket)) 3465 break; 3466 } 3467 #ifdef DIAGNOSTIC 3468 /* 3469 * This should never happen; we should always find a 3470 * non-empty bucket. 3471 */ 3472 if (scp2 == scp) 3473 panic("syn_cache_insert: cacheoverflow: " 3474 "impossible"); 3475 #endif 3476 } 3477 sc2 = TAILQ_FIRST(&scp2->sch_bucket); 3478 SYN_CACHE_RM(sc2); 3479 SYN_CACHE_PUT(sc2); 3480 } 3481 3482 /* 3483 * Initialize the entry's timer. 3484 */ 3485 sc->sc_rxttot = 0; 3486 sc->sc_rxtshift = 0; 3487 SYN_CACHE_TIMER_ARM(sc); 3488 3489 /* Link it from tcpcb entry */ 3490 LIST_INSERT_HEAD(&tp->t_sc, sc, sc_tpq); 3491 3492 /* Put it into the bucket. */ 3493 TAILQ_INSERT_TAIL(&scp->sch_bucket, sc, sc_bucketq); 3494 scp->sch_length++; 3495 syn_cache_count++; 3496 3497 tcpstat.tcps_sc_added++; 3498 splx(s); 3499 } 3500 3501 /* 3502 * Walk the timer queues, looking for SYN,ACKs that need to be retransmitted. 3503 * If we have retransmitted an entry the maximum number of times, expire 3504 * that entry. 3505 */ 3506 void 3507 syn_cache_timer(void *arg) 3508 { 3509 struct syn_cache *sc = arg; 3510 int s; 3511 3512 s = splsoftnet(); 3513 callout_ack(&sc->sc_timer); 3514 3515 if (__predict_false(sc->sc_flags & SCF_DEAD)) { 3516 tcpstat.tcps_sc_delayed_free++; 3517 pool_put(&syn_cache_pool, sc); 3518 splx(s); 3519 return; 3520 } 3521 3522 if (__predict_false(sc->sc_rxtshift == TCP_MAXRXTSHIFT)) { 3523 /* Drop it -- too many retransmissions. */ 3524 goto dropit; 3525 } 3526 3527 /* 3528 * Compute the total amount of time this entry has 3529 * been on a queue. If this entry has been on longer 3530 * than the keep alive timer would allow, expire it. 3531 */ 3532 sc->sc_rxttot += sc->sc_rxtcur; 3533 if (sc->sc_rxttot >= TCPTV_KEEP_INIT) 3534 goto dropit; 3535 3536 tcpstat.tcps_sc_retransmitted++; 3537 (void) syn_cache_respond(sc, NULL); 3538 3539 /* Advance the timer back-off. */ 3540 sc->sc_rxtshift++; 3541 SYN_CACHE_TIMER_ARM(sc); 3542 3543 splx(s); 3544 return; 3545 3546 dropit: 3547 tcpstat.tcps_sc_timed_out++; 3548 SYN_CACHE_RM(sc); 3549 SYN_CACHE_PUT(sc); 3550 splx(s); 3551 } 3552 3553 /* 3554 * Remove syn cache created by the specified tcb entry, 3555 * because this does not make sense to keep them 3556 * (if there's no tcb entry, syn cache entry will never be used) 3557 */ 3558 void 3559 syn_cache_cleanup(struct tcpcb *tp) 3560 { 3561 struct syn_cache *sc, *nsc; 3562 int s; 3563 3564 s = splsoftnet(); 3565 3566 for (sc = LIST_FIRST(&tp->t_sc); sc != NULL; sc = nsc) { 3567 nsc = LIST_NEXT(sc, sc_tpq); 3568 3569 #ifdef DIAGNOSTIC 3570 if (sc->sc_tp != tp) 3571 panic("invalid sc_tp in syn_cache_cleanup"); 3572 #endif 3573 SYN_CACHE_RM(sc); 3574 SYN_CACHE_PUT(sc); 3575 } 3576 /* just for safety */ 3577 LIST_INIT(&tp->t_sc); 3578 3579 splx(s); 3580 } 3581 3582 /* 3583 * Find an entry in the syn cache. 3584 */ 3585 struct syn_cache * 3586 syn_cache_lookup(const struct sockaddr *src, const struct sockaddr *dst, 3587 struct syn_cache_head **headp) 3588 { 3589 struct syn_cache *sc; 3590 struct syn_cache_head *scp; 3591 u_int32_t hash; 3592 int s; 3593 3594 SYN_HASHALL(hash, src, dst); 3595 3596 scp = &tcp_syn_cache[hash % tcp_syn_cache_size]; 3597 *headp = scp; 3598 s = splsoftnet(); 3599 for (sc = TAILQ_FIRST(&scp->sch_bucket); sc != NULL; 3600 sc = TAILQ_NEXT(sc, sc_bucketq)) { 3601 if (sc->sc_hash != hash) 3602 continue; 3603 if (!bcmp(&sc->sc_src, src, src->sa_len) && 3604 !bcmp(&sc->sc_dst, dst, dst->sa_len)) { 3605 splx(s); 3606 return (sc); 3607 } 3608 } 3609 splx(s); 3610 return (NULL); 3611 } 3612 3613 /* 3614 * This function gets called when we receive an ACK for a 3615 * socket in the LISTEN state. We look up the connection 3616 * in the syn cache, and if its there, we pull it out of 3617 * the cache and turn it into a full-blown connection in 3618 * the SYN-RECEIVED state. 3619 * 3620 * The return values may not be immediately obvious, and their effects 3621 * can be subtle, so here they are: 3622 * 3623 * NULL SYN was not found in cache; caller should drop the 3624 * packet and send an RST. 3625 * 3626 * -1 We were unable to create the new connection, and are 3627 * aborting it. An ACK,RST is being sent to the peer 3628 * (unless we got screwey sequence numbners; see below), 3629 * because the 3-way handshake has been completed. Caller 3630 * should not free the mbuf, since we may be using it. If 3631 * we are not, we will free it. 3632 * 3633 * Otherwise, the return value is a pointer to the new socket 3634 * associated with the connection. 3635 */ 3636 struct socket * 3637 syn_cache_get(struct sockaddr *src, struct sockaddr *dst, 3638 struct tcphdr *th, unsigned int hlen, unsigned int tlen, 3639 struct socket *so, struct mbuf *m) 3640 { 3641 struct syn_cache *sc; 3642 struct syn_cache_head *scp; 3643 struct inpcb *inp = NULL; 3644 #ifdef INET6 3645 struct in6pcb *in6p = NULL; 3646 #endif 3647 struct tcpcb *tp = 0; 3648 struct mbuf *am; 3649 int s; 3650 struct socket *oso; 3651 3652 s = splsoftnet(); 3653 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 3654 splx(s); 3655 return (NULL); 3656 } 3657 3658 /* 3659 * Verify the sequence and ack numbers. Try getting the correct 3660 * response again. 3661 */ 3662 if ((th->th_ack != sc->sc_iss + 1) || 3663 SEQ_LEQ(th->th_seq, sc->sc_irs) || 3664 SEQ_GT(th->th_seq, sc->sc_irs + 1 + sc->sc_win)) { 3665 (void) syn_cache_respond(sc, m); 3666 splx(s); 3667 return ((struct socket *)(-1)); 3668 } 3669 3670 /* Remove this cache entry */ 3671 SYN_CACHE_RM(sc); 3672 splx(s); 3673 3674 /* 3675 * Ok, create the full blown connection, and set things up 3676 * as they would have been set up if we had created the 3677 * connection when the SYN arrived. If we can't create 3678 * the connection, abort it. 3679 */ 3680 /* 3681 * inp still has the OLD in_pcb stuff, set the 3682 * v6-related flags on the new guy, too. This is 3683 * done particularly for the case where an AF_INET6 3684 * socket is bound only to a port, and a v4 connection 3685 * comes in on that port. 3686 * we also copy the flowinfo from the original pcb 3687 * to the new one. 3688 */ 3689 oso = so; 3690 so = sonewconn(so, SS_ISCONNECTED); 3691 if (so == NULL) 3692 goto resetandabort; 3693 3694 switch (so->so_proto->pr_domain->dom_family) { 3695 #ifdef INET 3696 case AF_INET: 3697 inp = sotoinpcb(so); 3698 break; 3699 #endif 3700 #ifdef INET6 3701 case AF_INET6: 3702 in6p = sotoin6pcb(so); 3703 break; 3704 #endif 3705 } 3706 switch (src->sa_family) { 3707 #ifdef INET 3708 case AF_INET: 3709 if (inp) { 3710 inp->inp_laddr = ((struct sockaddr_in *)dst)->sin_addr; 3711 inp->inp_lport = ((struct sockaddr_in *)dst)->sin_port; 3712 inp->inp_options = ip_srcroute(); 3713 in_pcbstate(inp, INP_BOUND); 3714 if (inp->inp_options == NULL) { 3715 inp->inp_options = sc->sc_ipopts; 3716 sc->sc_ipopts = NULL; 3717 } 3718 } 3719 #ifdef INET6 3720 else if (in6p) { 3721 /* IPv4 packet to AF_INET6 socket */ 3722 bzero(&in6p->in6p_laddr, sizeof(in6p->in6p_laddr)); 3723 in6p->in6p_laddr.s6_addr16[5] = htons(0xffff); 3724 bcopy(&((struct sockaddr_in *)dst)->sin_addr, 3725 &in6p->in6p_laddr.s6_addr32[3], 3726 sizeof(((struct sockaddr_in *)dst)->sin_addr)); 3727 in6p->in6p_lport = ((struct sockaddr_in *)dst)->sin_port; 3728 in6totcpcb(in6p)->t_family = AF_INET; 3729 if (sotoin6pcb(oso)->in6p_flags & IN6P_IPV6_V6ONLY) 3730 in6p->in6p_flags |= IN6P_IPV6_V6ONLY; 3731 else 3732 in6p->in6p_flags &= ~IN6P_IPV6_V6ONLY; 3733 in6_pcbstate(in6p, IN6P_BOUND); 3734 } 3735 #endif 3736 break; 3737 #endif 3738 #ifdef INET6 3739 case AF_INET6: 3740 if (in6p) { 3741 in6p->in6p_laddr = ((struct sockaddr_in6 *)dst)->sin6_addr; 3742 in6p->in6p_lport = ((struct sockaddr_in6 *)dst)->sin6_port; 3743 in6_pcbstate(in6p, IN6P_BOUND); 3744 } 3745 break; 3746 #endif 3747 } 3748 #ifdef INET6 3749 if (in6p && in6totcpcb(in6p)->t_family == AF_INET6 && sotoinpcb(oso)) { 3750 struct in6pcb *oin6p = sotoin6pcb(oso); 3751 /* inherit socket options from the listening socket */ 3752 in6p->in6p_flags |= (oin6p->in6p_flags & IN6P_CONTROLOPTS); 3753 if (in6p->in6p_flags & IN6P_CONTROLOPTS) { 3754 m_freem(in6p->in6p_options); 3755 in6p->in6p_options = 0; 3756 } 3757 ip6_savecontrol(in6p, &in6p->in6p_options, 3758 mtod(m, struct ip6_hdr *), m); 3759 } 3760 #endif 3761 3762 #if defined(IPSEC) || defined(FAST_IPSEC) 3763 /* 3764 * we make a copy of policy, instead of sharing the policy, 3765 * for better behavior in terms of SA lookup and dead SA removal. 3766 */ 3767 if (inp) { 3768 /* copy old policy into new socket's */ 3769 if (ipsec_copy_pcbpolicy(sotoinpcb(oso)->inp_sp, inp->inp_sp)) 3770 printf("tcp_input: could not copy policy\n"); 3771 } 3772 #ifdef INET6 3773 else if (in6p) { 3774 /* copy old policy into new socket's */ 3775 if (ipsec_copy_pcbpolicy(sotoin6pcb(oso)->in6p_sp, 3776 in6p->in6p_sp)) 3777 printf("tcp_input: could not copy policy\n"); 3778 } 3779 #endif 3780 #endif 3781 3782 /* 3783 * Give the new socket our cached route reference. 3784 */ 3785 if (inp) 3786 inp->inp_route = sc->sc_route4; /* struct assignment */ 3787 #ifdef INET6 3788 else 3789 in6p->in6p_route = sc->sc_route6; 3790 #endif 3791 sc->sc_route4.ro_rt = NULL; 3792 3793 am = m_get(M_DONTWAIT, MT_SONAME); /* XXX */ 3794 if (am == NULL) 3795 goto resetandabort; 3796 MCLAIM(am, &tcp_mowner); 3797 am->m_len = src->sa_len; 3798 bcopy(src, mtod(am, caddr_t), src->sa_len); 3799 if (inp) { 3800 if (in_pcbconnect(inp, am, NULL)) { 3801 (void) m_free(am); 3802 goto resetandabort; 3803 } 3804 } 3805 #ifdef INET6 3806 else if (in6p) { 3807 if (src->sa_family == AF_INET) { 3808 /* IPv4 packet to AF_INET6 socket */ 3809 struct sockaddr_in6 *sin6; 3810 sin6 = mtod(am, struct sockaddr_in6 *); 3811 am->m_len = sizeof(*sin6); 3812 bzero(sin6, sizeof(*sin6)); 3813 sin6->sin6_family = AF_INET6; 3814 sin6->sin6_len = sizeof(*sin6); 3815 sin6->sin6_port = ((struct sockaddr_in *)src)->sin_port; 3816 sin6->sin6_addr.s6_addr16[5] = htons(0xffff); 3817 bcopy(&((struct sockaddr_in *)src)->sin_addr, 3818 &sin6->sin6_addr.s6_addr32[3], 3819 sizeof(sin6->sin6_addr.s6_addr32[3])); 3820 } 3821 if (in6_pcbconnect(in6p, am, NULL)) { 3822 (void) m_free(am); 3823 goto resetandabort; 3824 } 3825 } 3826 #endif 3827 else { 3828 (void) m_free(am); 3829 goto resetandabort; 3830 } 3831 (void) m_free(am); 3832 3833 if (inp) 3834 tp = intotcpcb(inp); 3835 #ifdef INET6 3836 else if (in6p) 3837 tp = in6totcpcb(in6p); 3838 #endif 3839 else 3840 tp = NULL; 3841 tp->t_flags = sototcpcb(oso)->t_flags & TF_NODELAY; 3842 if (sc->sc_request_r_scale != 15) { 3843 tp->requested_s_scale = sc->sc_requested_s_scale; 3844 tp->request_r_scale = sc->sc_request_r_scale; 3845 tp->snd_scale = sc->sc_requested_s_scale; 3846 tp->rcv_scale = sc->sc_request_r_scale; 3847 tp->t_flags |= TF_REQ_SCALE|TF_RCVD_SCALE; 3848 } 3849 if (sc->sc_flags & SCF_TIMESTAMP) 3850 tp->t_flags |= TF_REQ_TSTMP|TF_RCVD_TSTMP; 3851 tp->ts_timebase = sc->sc_timebase; 3852 3853 tp->t_template = tcp_template(tp); 3854 if (tp->t_template == 0) { 3855 tp = tcp_drop(tp, ENOBUFS); /* destroys socket */ 3856 so = NULL; 3857 m_freem(m); 3858 goto abort; 3859 } 3860 3861 tp->iss = sc->sc_iss; 3862 tp->irs = sc->sc_irs; 3863 tcp_sendseqinit(tp); 3864 tcp_rcvseqinit(tp); 3865 tp->t_state = TCPS_SYN_RECEIVED; 3866 TCP_TIMER_ARM(tp, TCPT_KEEP, TCPTV_KEEP_INIT); 3867 tcpstat.tcps_accepts++; 3868 3869 if ((sc->sc_flags & SCF_SACK_PERMIT) && tcp_do_sack) 3870 tp->t_flags |= TF_WILL_SACK; 3871 3872 if ((sc->sc_flags & SCF_ECN_PERMIT) && tcp_do_ecn) 3873 tp->t_flags |= TF_ECN_PERMIT; 3874 3875 #ifdef TCP_SIGNATURE 3876 if (sc->sc_flags & SCF_SIGNATURE) 3877 tp->t_flags |= TF_SIGNATURE; 3878 #endif 3879 3880 /* Initialize tp->t_ourmss before we deal with the peer's! */ 3881 tp->t_ourmss = sc->sc_ourmaxseg; 3882 tcp_mss_from_peer(tp, sc->sc_peermaxseg); 3883 3884 /* 3885 * Initialize the initial congestion window. If we 3886 * had to retransmit the SYN,ACK, we must initialize cwnd 3887 * to 1 segment (i.e. the Loss Window). 3888 */ 3889 if (sc->sc_rxtshift) 3890 tp->snd_cwnd = tp->t_peermss; 3891 else { 3892 int ss = tcp_init_win; 3893 #ifdef INET 3894 if (inp != NULL && in_localaddr(inp->inp_faddr)) 3895 ss = tcp_init_win_local; 3896 #endif 3897 #ifdef INET6 3898 if (in6p != NULL && in6_localaddr(&in6p->in6p_faddr)) 3899 ss = tcp_init_win_local; 3900 #endif 3901 tp->snd_cwnd = TCP_INITIAL_WINDOW(ss, tp->t_peermss); 3902 } 3903 3904 tcp_rmx_rtt(tp); 3905 tp->snd_wl1 = sc->sc_irs; 3906 tp->rcv_up = sc->sc_irs + 1; 3907 3908 /* 3909 * This is what whould have happened in tcp_output() when 3910 * the SYN,ACK was sent. 3911 */ 3912 tp->snd_up = tp->snd_una; 3913 tp->snd_max = tp->snd_nxt = tp->iss+1; 3914 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 3915 if (sc->sc_win > 0 && SEQ_GT(tp->rcv_nxt + sc->sc_win, tp->rcv_adv)) 3916 tp->rcv_adv = tp->rcv_nxt + sc->sc_win; 3917 tp->last_ack_sent = tp->rcv_nxt; 3918 tp->t_partialacks = -1; 3919 tp->t_dupacks = 0; 3920 3921 tcpstat.tcps_sc_completed++; 3922 SYN_CACHE_PUT(sc); 3923 return (so); 3924 3925 resetandabort: 3926 (void)tcp_respond(NULL, m, m, th, (tcp_seq)0, th->th_ack, TH_RST); 3927 abort: 3928 if (so != NULL) 3929 (void) soabort(so); 3930 SYN_CACHE_PUT(sc); 3931 tcpstat.tcps_sc_aborted++; 3932 return ((struct socket *)(-1)); 3933 } 3934 3935 /* 3936 * This function is called when we get a RST for a 3937 * non-existent connection, so that we can see if the 3938 * connection is in the syn cache. If it is, zap it. 3939 */ 3940 3941 void 3942 syn_cache_reset(struct sockaddr *src, struct sockaddr *dst, struct tcphdr *th) 3943 { 3944 struct syn_cache *sc; 3945 struct syn_cache_head *scp; 3946 int s = splsoftnet(); 3947 3948 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 3949 splx(s); 3950 return; 3951 } 3952 if (SEQ_LT(th->th_seq, sc->sc_irs) || 3953 SEQ_GT(th->th_seq, sc->sc_irs+1)) { 3954 splx(s); 3955 return; 3956 } 3957 SYN_CACHE_RM(sc); 3958 splx(s); 3959 tcpstat.tcps_sc_reset++; 3960 SYN_CACHE_PUT(sc); 3961 } 3962 3963 void 3964 syn_cache_unreach(const struct sockaddr *src, const struct sockaddr *dst, 3965 struct tcphdr *th) 3966 { 3967 struct syn_cache *sc; 3968 struct syn_cache_head *scp; 3969 int s; 3970 3971 s = splsoftnet(); 3972 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 3973 splx(s); 3974 return; 3975 } 3976 /* If the sequence number != sc_iss, then it's a bogus ICMP msg */ 3977 if (ntohl (th->th_seq) != sc->sc_iss) { 3978 splx(s); 3979 return; 3980 } 3981 3982 /* 3983 * If we've retransmitted 3 times and this is our second error, 3984 * we remove the entry. Otherwise, we allow it to continue on. 3985 * This prevents us from incorrectly nuking an entry during a 3986 * spurious network outage. 3987 * 3988 * See tcp_notify(). 3989 */ 3990 if ((sc->sc_flags & SCF_UNREACH) == 0 || sc->sc_rxtshift < 3) { 3991 sc->sc_flags |= SCF_UNREACH; 3992 splx(s); 3993 return; 3994 } 3995 3996 SYN_CACHE_RM(sc); 3997 splx(s); 3998 tcpstat.tcps_sc_unreach++; 3999 SYN_CACHE_PUT(sc); 4000 } 4001 4002 /* 4003 * Given a LISTEN socket and an inbound SYN request, add 4004 * this to the syn cache, and send back a segment: 4005 * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK> 4006 * to the source. 4007 * 4008 * IMPORTANT NOTE: We do _NOT_ ACK data that might accompany the SYN. 4009 * Doing so would require that we hold onto the data and deliver it 4010 * to the application. However, if we are the target of a SYN-flood 4011 * DoS attack, an attacker could send data which would eventually 4012 * consume all available buffer space if it were ACKed. By not ACKing 4013 * the data, we avoid this DoS scenario. 4014 */ 4015 4016 int 4017 syn_cache_add(struct sockaddr *src, struct sockaddr *dst, struct tcphdr *th, 4018 unsigned int hlen, struct socket *so, struct mbuf *m, u_char *optp, 4019 int optlen, struct tcp_opt_info *oi) 4020 { 4021 struct tcpcb tb, *tp; 4022 long win; 4023 struct syn_cache *sc; 4024 struct syn_cache_head *scp; 4025 struct mbuf *ipopts; 4026 struct tcp_opt_info opti; 4027 4028 tp = sototcpcb(so); 4029 4030 bzero(&opti, sizeof(opti)); 4031 4032 /* 4033 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN 4034 * 4035 * Note this check is performed in tcp_input() very early on. 4036 */ 4037 4038 /* 4039 * Initialize some local state. 4040 */ 4041 win = sbspace(&so->so_rcv); 4042 if (win > TCP_MAXWIN) 4043 win = TCP_MAXWIN; 4044 4045 switch (src->sa_family) { 4046 #ifdef INET 4047 case AF_INET: 4048 /* 4049 * Remember the IP options, if any. 4050 */ 4051 ipopts = ip_srcroute(); 4052 break; 4053 #endif 4054 default: 4055 ipopts = NULL; 4056 } 4057 4058 #ifdef TCP_SIGNATURE 4059 if (optp || (tp->t_flags & TF_SIGNATURE)) 4060 #else 4061 if (optp) 4062 #endif 4063 { 4064 tb.t_flags = tcp_do_rfc1323 ? (TF_REQ_SCALE|TF_REQ_TSTMP) : 0; 4065 #ifdef TCP_SIGNATURE 4066 tb.t_flags |= (tp->t_flags & TF_SIGNATURE); 4067 #endif 4068 tb.t_state = TCPS_LISTEN; 4069 if (tcp_dooptions(&tb, optp, optlen, th, m, m->m_pkthdr.len - 4070 sizeof(struct tcphdr) - optlen - hlen, oi) < 0) 4071 return (0); 4072 } else 4073 tb.t_flags = 0; 4074 4075 /* 4076 * See if we already have an entry for this connection. 4077 * If we do, resend the SYN,ACK. We do not count this 4078 * as a retransmission (XXX though maybe we should). 4079 */ 4080 if ((sc = syn_cache_lookup(src, dst, &scp)) != NULL) { 4081 tcpstat.tcps_sc_dupesyn++; 4082 if (ipopts) { 4083 /* 4084 * If we were remembering a previous source route, 4085 * forget it and use the new one we've been given. 4086 */ 4087 if (sc->sc_ipopts) 4088 (void) m_free(sc->sc_ipopts); 4089 sc->sc_ipopts = ipopts; 4090 } 4091 sc->sc_timestamp = tb.ts_recent; 4092 if (syn_cache_respond(sc, m) == 0) { 4093 tcpstat.tcps_sndacks++; 4094 tcpstat.tcps_sndtotal++; 4095 } 4096 return (1); 4097 } 4098 4099 sc = pool_get(&syn_cache_pool, PR_NOWAIT); 4100 if (sc == NULL) { 4101 if (ipopts) 4102 (void) m_free(ipopts); 4103 return (0); 4104 } 4105 4106 /* 4107 * Fill in the cache, and put the necessary IP and TCP 4108 * options into the reply. 4109 */ 4110 bzero(sc, sizeof(struct syn_cache)); 4111 callout_init(&sc->sc_timer); 4112 bcopy(src, &sc->sc_src, src->sa_len); 4113 bcopy(dst, &sc->sc_dst, dst->sa_len); 4114 sc->sc_flags = 0; 4115 sc->sc_ipopts = ipopts; 4116 sc->sc_irs = th->th_seq; 4117 switch (src->sa_family) { 4118 #ifdef INET 4119 case AF_INET: 4120 { 4121 struct sockaddr_in *srcin = (void *) src; 4122 struct sockaddr_in *dstin = (void *) dst; 4123 4124 sc->sc_iss = tcp_new_iss1(&dstin->sin_addr, 4125 &srcin->sin_addr, dstin->sin_port, 4126 srcin->sin_port, sizeof(dstin->sin_addr), 0); 4127 break; 4128 } 4129 #endif /* INET */ 4130 #ifdef INET6 4131 case AF_INET6: 4132 { 4133 struct sockaddr_in6 *srcin6 = (void *) src; 4134 struct sockaddr_in6 *dstin6 = (void *) dst; 4135 4136 sc->sc_iss = tcp_new_iss1(&dstin6->sin6_addr, 4137 &srcin6->sin6_addr, dstin6->sin6_port, 4138 srcin6->sin6_port, sizeof(dstin6->sin6_addr), 0); 4139 break; 4140 } 4141 #endif /* INET6 */ 4142 } 4143 sc->sc_peermaxseg = oi->maxseg; 4144 sc->sc_ourmaxseg = tcp_mss_to_advertise(m->m_flags & M_PKTHDR ? 4145 m->m_pkthdr.rcvif : NULL, 4146 sc->sc_src.sa.sa_family); 4147 sc->sc_win = win; 4148 sc->sc_timebase = tcp_now; /* see tcp_newtcpcb() */ 4149 sc->sc_timestamp = tb.ts_recent; 4150 if ((tb.t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP)) == 4151 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) 4152 sc->sc_flags |= SCF_TIMESTAMP; 4153 if ((tb.t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 4154 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 4155 sc->sc_requested_s_scale = tb.requested_s_scale; 4156 sc->sc_request_r_scale = 0; 4157 while (sc->sc_request_r_scale < TCP_MAX_WINSHIFT && 4158 TCP_MAXWIN << sc->sc_request_r_scale < 4159 so->so_rcv.sb_hiwat) 4160 sc->sc_request_r_scale++; 4161 } else { 4162 sc->sc_requested_s_scale = 15; 4163 sc->sc_request_r_scale = 15; 4164 } 4165 if ((tb.t_flags & TF_SACK_PERMIT) && tcp_do_sack) 4166 sc->sc_flags |= SCF_SACK_PERMIT; 4167 4168 /* 4169 * ECN setup packet recieved. 4170 */ 4171 if ((th->th_flags & (TH_ECE|TH_CWR)) && tcp_do_ecn) 4172 sc->sc_flags |= SCF_ECN_PERMIT; 4173 4174 #ifdef TCP_SIGNATURE 4175 if (tb.t_flags & TF_SIGNATURE) 4176 sc->sc_flags |= SCF_SIGNATURE; 4177 #endif 4178 sc->sc_tp = tp; 4179 if (syn_cache_respond(sc, m) == 0) { 4180 syn_cache_insert(sc, tp); 4181 tcpstat.tcps_sndacks++; 4182 tcpstat.tcps_sndtotal++; 4183 } else { 4184 SYN_CACHE_PUT(sc); 4185 tcpstat.tcps_sc_dropped++; 4186 } 4187 return (1); 4188 } 4189 4190 int 4191 syn_cache_respond(struct syn_cache *sc, struct mbuf *m) 4192 { 4193 struct route *ro; 4194 u_int8_t *optp; 4195 int optlen, error; 4196 u_int16_t tlen; 4197 struct ip *ip = NULL; 4198 #ifdef INET6 4199 struct ip6_hdr *ip6 = NULL; 4200 #endif 4201 struct tcpcb *tp = NULL; 4202 struct tcphdr *th; 4203 u_int hlen; 4204 struct socket *so; 4205 4206 switch (sc->sc_src.sa.sa_family) { 4207 case AF_INET: 4208 hlen = sizeof(struct ip); 4209 ro = &sc->sc_route4; 4210 break; 4211 #ifdef INET6 4212 case AF_INET6: 4213 hlen = sizeof(struct ip6_hdr); 4214 ro = (struct route *)&sc->sc_route6; 4215 break; 4216 #endif 4217 default: 4218 if (m) 4219 m_freem(m); 4220 return (EAFNOSUPPORT); 4221 } 4222 4223 /* Compute the size of the TCP options. */ 4224 optlen = 4 + (sc->sc_request_r_scale != 15 ? 4 : 0) + 4225 ((sc->sc_flags & SCF_SACK_PERMIT) ? (TCPOLEN_SACK_PERMITTED + 2) : 0) + 4226 #ifdef TCP_SIGNATURE 4227 ((sc->sc_flags & SCF_SIGNATURE) ? (TCPOLEN_SIGNATURE + 2) : 0) + 4228 #endif 4229 ((sc->sc_flags & SCF_TIMESTAMP) ? TCPOLEN_TSTAMP_APPA : 0); 4230 4231 tlen = hlen + sizeof(struct tcphdr) + optlen; 4232 4233 /* 4234 * Create the IP+TCP header from scratch. 4235 */ 4236 if (m) 4237 m_freem(m); 4238 #ifdef DIAGNOSTIC 4239 if (max_linkhdr + tlen > MCLBYTES) 4240 return (ENOBUFS); 4241 #endif 4242 MGETHDR(m, M_DONTWAIT, MT_DATA); 4243 if (m && tlen > MHLEN) { 4244 MCLGET(m, M_DONTWAIT); 4245 if ((m->m_flags & M_EXT) == 0) { 4246 m_freem(m); 4247 m = NULL; 4248 } 4249 } 4250 if (m == NULL) 4251 return (ENOBUFS); 4252 MCLAIM(m, &tcp_tx_mowner); 4253 4254 /* Fixup the mbuf. */ 4255 m->m_data += max_linkhdr; 4256 m->m_len = m->m_pkthdr.len = tlen; 4257 if (sc->sc_tp) { 4258 tp = sc->sc_tp; 4259 if (tp->t_inpcb) 4260 so = tp->t_inpcb->inp_socket; 4261 #ifdef INET6 4262 else if (tp->t_in6pcb) 4263 so = tp->t_in6pcb->in6p_socket; 4264 #endif 4265 else 4266 so = NULL; 4267 } else 4268 so = NULL; 4269 m->m_pkthdr.rcvif = NULL; 4270 memset(mtod(m, u_char *), 0, tlen); 4271 4272 switch (sc->sc_src.sa.sa_family) { 4273 case AF_INET: 4274 ip = mtod(m, struct ip *); 4275 ip->ip_v = 4; 4276 ip->ip_dst = sc->sc_src.sin.sin_addr; 4277 ip->ip_src = sc->sc_dst.sin.sin_addr; 4278 ip->ip_p = IPPROTO_TCP; 4279 th = (struct tcphdr *)(ip + 1); 4280 th->th_dport = sc->sc_src.sin.sin_port; 4281 th->th_sport = sc->sc_dst.sin.sin_port; 4282 break; 4283 #ifdef INET6 4284 case AF_INET6: 4285 ip6 = mtod(m, struct ip6_hdr *); 4286 ip6->ip6_vfc = IPV6_VERSION; 4287 ip6->ip6_dst = sc->sc_src.sin6.sin6_addr; 4288 ip6->ip6_src = sc->sc_dst.sin6.sin6_addr; 4289 ip6->ip6_nxt = IPPROTO_TCP; 4290 /* ip6_plen will be updated in ip6_output() */ 4291 th = (struct tcphdr *)(ip6 + 1); 4292 th->th_dport = sc->sc_src.sin6.sin6_port; 4293 th->th_sport = sc->sc_dst.sin6.sin6_port; 4294 break; 4295 #endif 4296 default: 4297 th = NULL; 4298 } 4299 4300 th->th_seq = htonl(sc->sc_iss); 4301 th->th_ack = htonl(sc->sc_irs + 1); 4302 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 4303 th->th_flags = TH_SYN|TH_ACK; 4304 th->th_win = htons(sc->sc_win); 4305 /* th_sum already 0 */ 4306 /* th_urp already 0 */ 4307 4308 /* Tack on the TCP options. */ 4309 optp = (u_int8_t *)(th + 1); 4310 *optp++ = TCPOPT_MAXSEG; 4311 *optp++ = 4; 4312 *optp++ = (sc->sc_ourmaxseg >> 8) & 0xff; 4313 *optp++ = sc->sc_ourmaxseg & 0xff; 4314 4315 if (sc->sc_request_r_scale != 15) { 4316 *((u_int32_t *)optp) = htonl(TCPOPT_NOP << 24 | 4317 TCPOPT_WINDOW << 16 | TCPOLEN_WINDOW << 8 | 4318 sc->sc_request_r_scale); 4319 optp += 4; 4320 } 4321 4322 if (sc->sc_flags & SCF_TIMESTAMP) { 4323 u_int32_t *lp = (u_int32_t *)(optp); 4324 /* Form timestamp option as shown in appendix A of RFC 1323. */ 4325 *lp++ = htonl(TCPOPT_TSTAMP_HDR); 4326 *lp++ = htonl(SYN_CACHE_TIMESTAMP(sc)); 4327 *lp = htonl(sc->sc_timestamp); 4328 optp += TCPOLEN_TSTAMP_APPA; 4329 } 4330 4331 if (sc->sc_flags & SCF_SACK_PERMIT) { 4332 u_int8_t *p = optp; 4333 4334 /* Let the peer know that we will SACK. */ 4335 p[0] = TCPOPT_SACK_PERMITTED; 4336 p[1] = 2; 4337 p[2] = TCPOPT_NOP; 4338 p[3] = TCPOPT_NOP; 4339 optp += 4; 4340 } 4341 4342 /* 4343 * Send ECN SYN-ACK setup packet. 4344 * Routes can be asymetric, so, even if we receive a packet 4345 * with ECE and CWR set, we must not assume no one will block 4346 * the ECE packet we are about to send. 4347 */ 4348 if ((sc->sc_flags & SCF_ECN_PERMIT) && tp && 4349 SEQ_GEQ(tp->snd_nxt, tp->snd_max)) { 4350 th->th_flags |= TH_ECE; 4351 tcpstat.tcps_ecn_shs++; 4352 4353 /* 4354 * draft-ietf-tcpm-ecnsyn-00.txt 4355 * 4356 * "[...] a TCP node MAY respond to an ECN-setup 4357 * SYN packet by setting ECT in the responding 4358 * ECN-setup SYN/ACK packet, indicating to routers 4359 * that the SYN/ACK packet is ECN-Capable. 4360 * This allows a congested router along the path 4361 * to mark the packet instead of dropping the 4362 * packet as an indication of congestion." 4363 * 4364 * "[...] There can be a great benefit in setting 4365 * an ECN-capable codepoint in SYN/ACK packets [...] 4366 * Congestion is most likely to occur in 4367 * the server-to-client direction. As a result, 4368 * setting an ECN-capable codepoint in SYN/ACK 4369 * packets can reduce the occurence of three-second 4370 * retransmit timeouts resulting from the drop 4371 * of SYN/ACK packets." 4372 * 4373 * Page 4 and 6, January 2006. 4374 */ 4375 4376 switch (sc->sc_src.sa.sa_family) { 4377 #ifdef INET 4378 case AF_INET: 4379 ip->ip_tos |= IPTOS_ECN_ECT0; 4380 break; 4381 #endif 4382 #ifdef INET6 4383 case AF_INET6: 4384 ip6->ip6_flow |= htonl(IPTOS_ECN_ECT0 << 20); 4385 break; 4386 #endif 4387 } 4388 tcpstat.tcps_ecn_ect++; 4389 } 4390 4391 #ifdef TCP_SIGNATURE 4392 if (sc->sc_flags & SCF_SIGNATURE) { 4393 struct secasvar *sav; 4394 u_int8_t *sigp; 4395 4396 sav = tcp_signature_getsav(m, th); 4397 4398 if (sav == NULL) { 4399 if (m) 4400 m_freem(m); 4401 return (EPERM); 4402 } 4403 4404 *optp++ = TCPOPT_SIGNATURE; 4405 *optp++ = TCPOLEN_SIGNATURE; 4406 sigp = optp; 4407 bzero(optp, TCP_SIGLEN); 4408 optp += TCP_SIGLEN; 4409 *optp++ = TCPOPT_NOP; 4410 *optp++ = TCPOPT_EOL; 4411 4412 (void)tcp_signature(m, th, hlen, sav, sigp); 4413 4414 key_sa_recordxfer(sav, m); 4415 #ifdef FAST_IPSEC 4416 KEY_FREESAV(&sav); 4417 #else 4418 key_freesav(sav); 4419 #endif 4420 } 4421 #endif 4422 4423 /* Compute the packet's checksum. */ 4424 switch (sc->sc_src.sa.sa_family) { 4425 case AF_INET: 4426 ip->ip_len = htons(tlen - hlen); 4427 th->th_sum = 0; 4428 th->th_sum = in4_cksum(m, IPPROTO_TCP, hlen, tlen - hlen); 4429 break; 4430 #ifdef INET6 4431 case AF_INET6: 4432 ip6->ip6_plen = htons(tlen - hlen); 4433 th->th_sum = 0; 4434 th->th_sum = in6_cksum(m, IPPROTO_TCP, hlen, tlen - hlen); 4435 break; 4436 #endif 4437 } 4438 4439 /* 4440 * Fill in some straggling IP bits. Note the stack expects 4441 * ip_len to be in host order, for convenience. 4442 */ 4443 switch (sc->sc_src.sa.sa_family) { 4444 #ifdef INET 4445 case AF_INET: 4446 ip->ip_len = htons(tlen); 4447 ip->ip_ttl = ip_defttl; 4448 /* XXX tos? */ 4449 break; 4450 #endif 4451 #ifdef INET6 4452 case AF_INET6: 4453 ip6->ip6_vfc &= ~IPV6_VERSION_MASK; 4454 ip6->ip6_vfc |= IPV6_VERSION; 4455 ip6->ip6_plen = htons(tlen - hlen); 4456 /* ip6_hlim will be initialized afterwards */ 4457 /* XXX flowlabel? */ 4458 break; 4459 #endif 4460 } 4461 4462 /* XXX use IPsec policy on listening socket, on SYN ACK */ 4463 tp = sc->sc_tp; 4464 4465 switch (sc->sc_src.sa.sa_family) { 4466 #ifdef INET 4467 case AF_INET: 4468 error = ip_output(m, sc->sc_ipopts, ro, 4469 (ip_mtudisc ? IP_MTUDISC : 0), 4470 (struct ip_moptions *)NULL, so); 4471 break; 4472 #endif 4473 #ifdef INET6 4474 case AF_INET6: 4475 ip6->ip6_hlim = in6_selecthlim(NULL, 4476 ro->ro_rt ? ro->ro_rt->rt_ifp : NULL); 4477 4478 error = ip6_output(m, NULL /*XXX*/, (struct route_in6 *)ro, 0, 4479 (struct ip6_moptions *)0, so, NULL); 4480 break; 4481 #endif 4482 default: 4483 error = EAFNOSUPPORT; 4484 break; 4485 } 4486 return (error); 4487 } 4488