1 /* $NetBSD: tcp_input.c,v 1.279 2008/02/05 09:38:47 yamt 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 1.279 2008/02/05 09:38:47 yamt 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 #include <sys/lwp.h> /* for lwp0 */ 178 179 #include <net/if.h> 180 #include <net/route.h> 181 #include <net/if_types.h> 182 183 #include <netinet/in.h> 184 #include <netinet/in_systm.h> 185 #include <netinet/ip.h> 186 #include <netinet/in_pcb.h> 187 #include <netinet/in_var.h> 188 #include <netinet/ip_var.h> 189 #include <netinet/in_offload.h> 190 191 #ifdef INET6 192 #ifndef INET 193 #include <netinet/in.h> 194 #endif 195 #include <netinet/ip6.h> 196 #include <netinet6/ip6_var.h> 197 #include <netinet6/in6_pcb.h> 198 #include <netinet6/ip6_var.h> 199 #include <netinet6/in6_var.h> 200 #include <netinet/icmp6.h> 201 #include <netinet6/nd6.h> 202 #ifdef TCP_SIGNATURE 203 #include <netinet6/scope6_var.h> 204 #endif 205 #endif 206 207 #ifndef INET6 208 /* always need ip6.h for IP6_EXTHDR_GET */ 209 #include <netinet/ip6.h> 210 #endif 211 212 #include <netinet/tcp.h> 213 #include <netinet/tcp_fsm.h> 214 #include <netinet/tcp_seq.h> 215 #include <netinet/tcp_timer.h> 216 #include <netinet/tcp_var.h> 217 #include <netinet/tcpip.h> 218 #include <netinet/tcp_congctl.h> 219 #include <netinet/tcp_debug.h> 220 221 #include <machine/stdarg.h> 222 223 #ifdef IPSEC 224 #include <netinet6/ipsec.h> 225 #include <netkey/key.h> 226 #endif /*IPSEC*/ 227 #ifdef INET6 228 #include "faith.h" 229 #if defined(NFAITH) && NFAITH > 0 230 #include <net/if_faith.h> 231 #endif 232 #endif /* IPSEC */ 233 234 #ifdef FAST_IPSEC 235 #include <netipsec/ipsec.h> 236 #include <netipsec/ipsec_var.h> /* XXX ipsecstat namespace */ 237 #include <netipsec/key.h> 238 #ifdef INET6 239 #include <netipsec/ipsec6.h> 240 #endif 241 #endif /* FAST_IPSEC*/ 242 243 int tcprexmtthresh = 3; 244 int tcp_log_refused; 245 246 int tcp_do_autorcvbuf = 0; 247 int tcp_autorcvbuf_inc = 16 * 1024; 248 int tcp_autorcvbuf_max = 256 * 1024; 249 250 static int tcp_rst_ppslim_count = 0; 251 static struct timeval tcp_rst_ppslim_last; 252 static int tcp_ackdrop_ppslim_count = 0; 253 static struct timeval tcp_ackdrop_ppslim_last; 254 255 #define TCP_PAWS_IDLE (24U * 24 * 60 * 60 * PR_SLOWHZ) 256 257 /* for modulo comparisons of timestamps */ 258 #define TSTMP_LT(a,b) ((int)((a)-(b)) < 0) 259 #define TSTMP_GEQ(a,b) ((int)((a)-(b)) >= 0) 260 261 /* 262 * Neighbor Discovery, Neighbor Unreachability Detection Upper layer hint. 263 */ 264 #ifdef INET6 265 static inline void 266 nd6_hint(struct tcpcb *tp) 267 { 268 struct rtentry *rt; 269 270 if (tp != NULL && tp->t_in6pcb != NULL && tp->t_family == AF_INET6 && 271 (rt = rtcache_validate(&tp->t_in6pcb->in6p_route)) != NULL) 272 nd6_nud_hint(rt, NULL, 0); 273 } 274 #else 275 static inline void 276 nd6_hint(struct tcpcb *tp) 277 { 278 } 279 #endif 280 281 /* 282 * Macro to compute ACK transmission behavior. Delay the ACK unless 283 * we have already delayed an ACK (must send an ACK every two segments). 284 * We also ACK immediately if we received a PUSH and the ACK-on-PUSH 285 * option is enabled. 286 */ 287 #define TCP_SETUP_ACK(tp, th) \ 288 do { \ 289 if ((tp)->t_flags & TF_DELACK || \ 290 (tcp_ack_on_push && (th)->th_flags & TH_PUSH)) \ 291 tp->t_flags |= TF_ACKNOW; \ 292 else \ 293 TCP_SET_DELACK(tp); \ 294 } while (/*CONSTCOND*/ 0) 295 296 #define ICMP_CHECK(tp, th, acked) \ 297 do { \ 298 /* \ 299 * If we had a pending ICMP message that \ 300 * refers to data that have just been \ 301 * acknowledged, disregard the recorded ICMP \ 302 * message. \ 303 */ \ 304 if (((tp)->t_flags & TF_PMTUD_PEND) && \ 305 SEQ_GT((th)->th_ack, (tp)->t_pmtud_th_seq)) \ 306 (tp)->t_flags &= ~TF_PMTUD_PEND; \ 307 \ 308 /* \ 309 * Keep track of the largest chunk of data \ 310 * acknowledged since last PMTU update \ 311 */ \ 312 if ((tp)->t_pmtud_mss_acked < (acked)) \ 313 (tp)->t_pmtud_mss_acked = (acked); \ 314 } while (/*CONSTCOND*/ 0) 315 316 /* 317 * Convert TCP protocol fields to host order for easier processing. 318 */ 319 #define TCP_FIELDS_TO_HOST(th) \ 320 do { \ 321 NTOHL((th)->th_seq); \ 322 NTOHL((th)->th_ack); \ 323 NTOHS((th)->th_win); \ 324 NTOHS((th)->th_urp); \ 325 } while (/*CONSTCOND*/ 0) 326 327 /* 328 * ... and reverse the above. 329 */ 330 #define TCP_FIELDS_TO_NET(th) \ 331 do { \ 332 HTONL((th)->th_seq); \ 333 HTONL((th)->th_ack); \ 334 HTONS((th)->th_win); \ 335 HTONS((th)->th_urp); \ 336 } while (/*CONSTCOND*/ 0) 337 338 #ifdef TCP_CSUM_COUNTERS 339 #include <sys/device.h> 340 341 #if defined(INET) 342 extern struct evcnt tcp_hwcsum_ok; 343 extern struct evcnt tcp_hwcsum_bad; 344 extern struct evcnt tcp_hwcsum_data; 345 extern struct evcnt tcp_swcsum; 346 #endif /* defined(INET) */ 347 #if defined(INET6) 348 extern struct evcnt tcp6_hwcsum_ok; 349 extern struct evcnt tcp6_hwcsum_bad; 350 extern struct evcnt tcp6_hwcsum_data; 351 extern struct evcnt tcp6_swcsum; 352 #endif /* defined(INET6) */ 353 354 #define TCP_CSUM_COUNTER_INCR(ev) (ev)->ev_count++ 355 356 #else 357 358 #define TCP_CSUM_COUNTER_INCR(ev) /* nothing */ 359 360 #endif /* TCP_CSUM_COUNTERS */ 361 362 #ifdef TCP_REASS_COUNTERS 363 #include <sys/device.h> 364 365 extern struct evcnt tcp_reass_; 366 extern struct evcnt tcp_reass_empty; 367 extern struct evcnt tcp_reass_iteration[8]; 368 extern struct evcnt tcp_reass_prependfirst; 369 extern struct evcnt tcp_reass_prepend; 370 extern struct evcnt tcp_reass_insert; 371 extern struct evcnt tcp_reass_inserttail; 372 extern struct evcnt tcp_reass_append; 373 extern struct evcnt tcp_reass_appendtail; 374 extern struct evcnt tcp_reass_overlaptail; 375 extern struct evcnt tcp_reass_overlapfront; 376 extern struct evcnt tcp_reass_segdup; 377 extern struct evcnt tcp_reass_fragdup; 378 379 #define TCP_REASS_COUNTER_INCR(ev) (ev)->ev_count++ 380 381 #else 382 383 #define TCP_REASS_COUNTER_INCR(ev) /* nothing */ 384 385 #endif /* TCP_REASS_COUNTERS */ 386 387 static int tcp_reass(struct tcpcb *, const struct tcphdr *, struct mbuf *, 388 int *); 389 static int tcp_dooptions(struct tcpcb *, const u_char *, int, 390 struct tcphdr *, struct mbuf *, int, struct tcp_opt_info *); 391 392 #ifdef INET 393 static void tcp4_log_refused(const struct ip *, const struct tcphdr *); 394 #endif 395 #ifdef INET6 396 static void tcp6_log_refused(const struct ip6_hdr *, const struct tcphdr *); 397 #endif 398 399 #define TRAVERSE(x) while ((x)->m_next) (x) = (x)->m_next 400 401 #if defined(MBUFTRACE) 402 struct mowner tcp_reass_mowner = MOWNER_INIT("tcp", "reass"); 403 #endif /* defined(MBUFTRACE) */ 404 405 static POOL_INIT(tcpipqent_pool, sizeof(struct ipqent), 0, 0, 0, "tcpipqepl", 406 NULL, IPL_VM); 407 408 struct ipqent * 409 tcpipqent_alloc() 410 { 411 struct ipqent *ipqe; 412 int s; 413 414 s = splvm(); 415 ipqe = pool_get(&tcpipqent_pool, PR_NOWAIT); 416 splx(s); 417 418 return ipqe; 419 } 420 421 void 422 tcpipqent_free(struct ipqent *ipqe) 423 { 424 int s; 425 426 s = splvm(); 427 pool_put(&tcpipqent_pool, ipqe); 428 splx(s); 429 } 430 431 static int 432 tcp_reass(struct tcpcb *tp, const struct tcphdr *th, struct mbuf *m, int *tlen) 433 { 434 struct ipqent *p, *q, *nq, *tiqe = NULL; 435 struct socket *so = NULL; 436 int pkt_flags; 437 tcp_seq pkt_seq; 438 unsigned pkt_len; 439 u_long rcvpartdupbyte = 0; 440 u_long rcvoobyte; 441 #ifdef TCP_REASS_COUNTERS 442 u_int count = 0; 443 #endif 444 445 if (tp->t_inpcb) 446 so = tp->t_inpcb->inp_socket; 447 #ifdef INET6 448 else if (tp->t_in6pcb) 449 so = tp->t_in6pcb->in6p_socket; 450 #endif 451 452 TCP_REASS_LOCK_CHECK(tp); 453 454 /* 455 * Call with th==0 after become established to 456 * force pre-ESTABLISHED data up to user socket. 457 */ 458 if (th == 0) 459 goto present; 460 461 m_claimm(m, &tcp_reass_mowner); 462 463 rcvoobyte = *tlen; 464 /* 465 * Copy these to local variables because the tcpiphdr 466 * gets munged while we are collapsing mbufs. 467 */ 468 pkt_seq = th->th_seq; 469 pkt_len = *tlen; 470 pkt_flags = th->th_flags; 471 472 TCP_REASS_COUNTER_INCR(&tcp_reass_); 473 474 if ((p = TAILQ_LAST(&tp->segq, ipqehead)) != NULL) { 475 /* 476 * When we miss a packet, the vast majority of time we get 477 * packets that follow it in order. So optimize for that. 478 */ 479 if (pkt_seq == p->ipqe_seq + p->ipqe_len) { 480 p->ipqe_len += pkt_len; 481 p->ipqe_flags |= pkt_flags; 482 m_cat(p->ipre_mlast, m); 483 TRAVERSE(p->ipre_mlast); 484 m = NULL; 485 tiqe = p; 486 TAILQ_REMOVE(&tp->timeq, p, ipqe_timeq); 487 TCP_REASS_COUNTER_INCR(&tcp_reass_appendtail); 488 goto skip_replacement; 489 } 490 /* 491 * While we're here, if the pkt is completely beyond 492 * anything we have, just insert it at the tail. 493 */ 494 if (SEQ_GT(pkt_seq, p->ipqe_seq + p->ipqe_len)) { 495 TCP_REASS_COUNTER_INCR(&tcp_reass_inserttail); 496 goto insert_it; 497 } 498 } 499 500 q = TAILQ_FIRST(&tp->segq); 501 502 if (q != NULL) { 503 /* 504 * If this segment immediately precedes the first out-of-order 505 * block, simply slap the segment in front of it and (mostly) 506 * skip the complicated logic. 507 */ 508 if (pkt_seq + pkt_len == q->ipqe_seq) { 509 q->ipqe_seq = pkt_seq; 510 q->ipqe_len += pkt_len; 511 q->ipqe_flags |= pkt_flags; 512 m_cat(m, q->ipqe_m); 513 q->ipqe_m = m; 514 q->ipre_mlast = m; /* last mbuf may have changed */ 515 TRAVERSE(q->ipre_mlast); 516 tiqe = q; 517 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 518 TCP_REASS_COUNTER_INCR(&tcp_reass_prependfirst); 519 goto skip_replacement; 520 } 521 } else { 522 TCP_REASS_COUNTER_INCR(&tcp_reass_empty); 523 } 524 525 /* 526 * Find a segment which begins after this one does. 527 */ 528 for (p = NULL; q != NULL; q = nq) { 529 nq = TAILQ_NEXT(q, ipqe_q); 530 #ifdef TCP_REASS_COUNTERS 531 count++; 532 #endif 533 /* 534 * If the received segment is just right after this 535 * fragment, merge the two together and then check 536 * for further overlaps. 537 */ 538 if (q->ipqe_seq + q->ipqe_len == pkt_seq) { 539 #ifdef TCPREASS_DEBUG 540 printf("tcp_reass[%p]: concat %u:%u(%u) to %u:%u(%u)\n", 541 tp, pkt_seq, pkt_seq + pkt_len, pkt_len, 542 q->ipqe_seq, q->ipqe_seq + q->ipqe_len, q->ipqe_len); 543 #endif 544 pkt_len += q->ipqe_len; 545 pkt_flags |= q->ipqe_flags; 546 pkt_seq = q->ipqe_seq; 547 m_cat(q->ipre_mlast, m); 548 TRAVERSE(q->ipre_mlast); 549 m = q->ipqe_m; 550 TCP_REASS_COUNTER_INCR(&tcp_reass_append); 551 goto free_ipqe; 552 } 553 /* 554 * If the received segment is completely past this 555 * fragment, we need to go the next fragment. 556 */ 557 if (SEQ_LT(q->ipqe_seq + q->ipqe_len, pkt_seq)) { 558 p = q; 559 continue; 560 } 561 /* 562 * If the fragment is past the received segment, 563 * it (or any following) can't be concatenated. 564 */ 565 if (SEQ_GT(q->ipqe_seq, pkt_seq + pkt_len)) { 566 TCP_REASS_COUNTER_INCR(&tcp_reass_insert); 567 break; 568 } 569 570 /* 571 * We've received all the data in this segment before. 572 * mark it as a duplicate and return. 573 */ 574 if (SEQ_LEQ(q->ipqe_seq, pkt_seq) && 575 SEQ_GEQ(q->ipqe_seq + q->ipqe_len, pkt_seq + pkt_len)) { 576 tcpstat.tcps_rcvduppack++; 577 tcpstat.tcps_rcvdupbyte += pkt_len; 578 tcp_new_dsack(tp, pkt_seq, pkt_len); 579 m_freem(m); 580 if (tiqe != NULL) { 581 tcpipqent_free(tiqe); 582 } 583 TCP_REASS_COUNTER_INCR(&tcp_reass_segdup); 584 return (0); 585 } 586 /* 587 * Received segment completely overlaps this fragment 588 * so we drop the fragment (this keeps the temporal 589 * ordering of segments correct). 590 */ 591 if (SEQ_GEQ(q->ipqe_seq, pkt_seq) && 592 SEQ_LEQ(q->ipqe_seq + q->ipqe_len, pkt_seq + pkt_len)) { 593 rcvpartdupbyte += q->ipqe_len; 594 m_freem(q->ipqe_m); 595 TCP_REASS_COUNTER_INCR(&tcp_reass_fragdup); 596 goto free_ipqe; 597 } 598 /* 599 * RX'ed segment extends past the end of the 600 * fragment. Drop the overlapping bytes. Then 601 * merge the fragment and segment then treat as 602 * a longer received packet. 603 */ 604 if (SEQ_LT(q->ipqe_seq, pkt_seq) && 605 SEQ_GT(q->ipqe_seq + q->ipqe_len, pkt_seq)) { 606 int overlap = q->ipqe_seq + q->ipqe_len - pkt_seq; 607 #ifdef TCPREASS_DEBUG 608 printf("tcp_reass[%p]: trim starting %d bytes of %u:%u(%u)\n", 609 tp, overlap, 610 pkt_seq, pkt_seq + pkt_len, pkt_len); 611 #endif 612 m_adj(m, overlap); 613 rcvpartdupbyte += overlap; 614 m_cat(q->ipre_mlast, m); 615 TRAVERSE(q->ipre_mlast); 616 m = q->ipqe_m; 617 pkt_seq = q->ipqe_seq; 618 pkt_len += q->ipqe_len - overlap; 619 rcvoobyte -= overlap; 620 TCP_REASS_COUNTER_INCR(&tcp_reass_overlaptail); 621 goto free_ipqe; 622 } 623 /* 624 * RX'ed segment extends past the front of the 625 * fragment. Drop the overlapping bytes on the 626 * received packet. The packet will then be 627 * contatentated with this fragment a bit later. 628 */ 629 if (SEQ_GT(q->ipqe_seq, pkt_seq) && 630 SEQ_LT(q->ipqe_seq, pkt_seq + pkt_len)) { 631 int overlap = pkt_seq + pkt_len - q->ipqe_seq; 632 #ifdef TCPREASS_DEBUG 633 printf("tcp_reass[%p]: trim trailing %d bytes of %u:%u(%u)\n", 634 tp, overlap, 635 pkt_seq, pkt_seq + pkt_len, pkt_len); 636 #endif 637 m_adj(m, -overlap); 638 pkt_len -= overlap; 639 rcvpartdupbyte += overlap; 640 TCP_REASS_COUNTER_INCR(&tcp_reass_overlapfront); 641 rcvoobyte -= overlap; 642 } 643 /* 644 * If the received segment immediates precedes this 645 * fragment then tack the fragment onto this segment 646 * and reinsert the data. 647 */ 648 if (q->ipqe_seq == pkt_seq + pkt_len) { 649 #ifdef TCPREASS_DEBUG 650 printf("tcp_reass[%p]: append %u:%u(%u) to %u:%u(%u)\n", 651 tp, q->ipqe_seq, q->ipqe_seq + q->ipqe_len, q->ipqe_len, 652 pkt_seq, pkt_seq + pkt_len, pkt_len); 653 #endif 654 pkt_len += q->ipqe_len; 655 pkt_flags |= q->ipqe_flags; 656 m_cat(m, q->ipqe_m); 657 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 658 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 659 tp->t_segqlen--; 660 KASSERT(tp->t_segqlen >= 0); 661 KASSERT(tp->t_segqlen != 0 || 662 (TAILQ_EMPTY(&tp->segq) && 663 TAILQ_EMPTY(&tp->timeq))); 664 if (tiqe == NULL) { 665 tiqe = q; 666 } else { 667 tcpipqent_free(q); 668 } 669 TCP_REASS_COUNTER_INCR(&tcp_reass_prepend); 670 break; 671 } 672 /* 673 * If the fragment is before the segment, remember it. 674 * When this loop is terminated, p will contain the 675 * pointer to fragment that is right before the received 676 * segment. 677 */ 678 if (SEQ_LEQ(q->ipqe_seq, pkt_seq)) 679 p = q; 680 681 continue; 682 683 /* 684 * This is a common operation. It also will allow 685 * to save doing a malloc/free in most instances. 686 */ 687 free_ipqe: 688 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 689 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 690 tp->t_segqlen--; 691 KASSERT(tp->t_segqlen >= 0); 692 KASSERT(tp->t_segqlen != 0 || 693 (TAILQ_EMPTY(&tp->segq) && TAILQ_EMPTY(&tp->timeq))); 694 if (tiqe == NULL) { 695 tiqe = q; 696 } else { 697 tcpipqent_free(q); 698 } 699 } 700 701 #ifdef TCP_REASS_COUNTERS 702 if (count > 7) 703 TCP_REASS_COUNTER_INCR(&tcp_reass_iteration[0]); 704 else if (count > 0) 705 TCP_REASS_COUNTER_INCR(&tcp_reass_iteration[count]); 706 #endif 707 708 insert_it: 709 710 /* 711 * Allocate a new queue entry since the received segment did not 712 * collapse onto any other out-of-order block; thus we are allocating 713 * a new block. If it had collapsed, tiqe would not be NULL and 714 * we would be reusing it. 715 * XXX If we can't, just drop the packet. XXX 716 */ 717 if (tiqe == NULL) { 718 tiqe = tcpipqent_alloc(); 719 if (tiqe == NULL) { 720 tcpstat.tcps_rcvmemdrop++; 721 m_freem(m); 722 return (0); 723 } 724 } 725 726 /* 727 * Update the counters. 728 */ 729 tcpstat.tcps_rcvoopack++; 730 tcpstat.tcps_rcvoobyte += rcvoobyte; 731 if (rcvpartdupbyte) { 732 tcpstat.tcps_rcvpartduppack++; 733 tcpstat.tcps_rcvpartdupbyte += rcvpartdupbyte; 734 } 735 736 /* 737 * Insert the new fragment queue entry into both queues. 738 */ 739 tiqe->ipqe_m = m; 740 tiqe->ipre_mlast = m; 741 tiqe->ipqe_seq = pkt_seq; 742 tiqe->ipqe_len = pkt_len; 743 tiqe->ipqe_flags = pkt_flags; 744 if (p == NULL) { 745 TAILQ_INSERT_HEAD(&tp->segq, tiqe, ipqe_q); 746 #ifdef TCPREASS_DEBUG 747 if (tiqe->ipqe_seq != tp->rcv_nxt) 748 printf("tcp_reass[%p]: insert %u:%u(%u) at front\n", 749 tp, pkt_seq, pkt_seq + pkt_len, pkt_len); 750 #endif 751 } else { 752 TAILQ_INSERT_AFTER(&tp->segq, p, tiqe, ipqe_q); 753 #ifdef TCPREASS_DEBUG 754 printf("tcp_reass[%p]: insert %u:%u(%u) after %u:%u(%u)\n", 755 tp, pkt_seq, pkt_seq + pkt_len, pkt_len, 756 p->ipqe_seq, p->ipqe_seq + p->ipqe_len, p->ipqe_len); 757 #endif 758 } 759 tp->t_segqlen++; 760 761 skip_replacement: 762 763 TAILQ_INSERT_HEAD(&tp->timeq, tiqe, ipqe_timeq); 764 765 present: 766 /* 767 * Present data to user, advancing rcv_nxt through 768 * completed sequence space. 769 */ 770 if (TCPS_HAVEESTABLISHED(tp->t_state) == 0) 771 return (0); 772 q = TAILQ_FIRST(&tp->segq); 773 if (q == NULL || q->ipqe_seq != tp->rcv_nxt) 774 return (0); 775 if (tp->t_state == TCPS_SYN_RECEIVED && q->ipqe_len) 776 return (0); 777 778 tp->rcv_nxt += q->ipqe_len; 779 pkt_flags = q->ipqe_flags & TH_FIN; 780 nd6_hint(tp); 781 782 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 783 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 784 tp->t_segqlen--; 785 KASSERT(tp->t_segqlen >= 0); 786 KASSERT(tp->t_segqlen != 0 || 787 (TAILQ_EMPTY(&tp->segq) && TAILQ_EMPTY(&tp->timeq))); 788 if (so->so_state & SS_CANTRCVMORE) 789 m_freem(q->ipqe_m); 790 else 791 sbappendstream(&so->so_rcv, q->ipqe_m); 792 tcpipqent_free(q); 793 sorwakeup(so); 794 return (pkt_flags); 795 } 796 797 #ifdef INET6 798 int 799 tcp6_input(struct mbuf **mp, int *offp, int proto) 800 { 801 struct mbuf *m = *mp; 802 803 /* 804 * draft-itojun-ipv6-tcp-to-anycast 805 * better place to put this in? 806 */ 807 if (m->m_flags & M_ANYCAST6) { 808 struct ip6_hdr *ip6; 809 if (m->m_len < sizeof(struct ip6_hdr)) { 810 if ((m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) { 811 tcpstat.tcps_rcvshort++; 812 return IPPROTO_DONE; 813 } 814 } 815 ip6 = mtod(m, struct ip6_hdr *); 816 icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR, 817 (char *)&ip6->ip6_dst - (char *)ip6); 818 return IPPROTO_DONE; 819 } 820 821 tcp_input(m, *offp, proto); 822 return IPPROTO_DONE; 823 } 824 #endif 825 826 #ifdef INET 827 static void 828 tcp4_log_refused(const struct ip *ip, const struct tcphdr *th) 829 { 830 char src[4*sizeof "123"]; 831 char dst[4*sizeof "123"]; 832 833 if (ip) { 834 strlcpy(src, inet_ntoa(ip->ip_src), sizeof(src)); 835 strlcpy(dst, inet_ntoa(ip->ip_dst), sizeof(dst)); 836 } 837 else { 838 strlcpy(src, "(unknown)", sizeof(src)); 839 strlcpy(dst, "(unknown)", sizeof(dst)); 840 } 841 log(LOG_INFO, 842 "Connection attempt to TCP %s:%d from %s:%d\n", 843 dst, ntohs(th->th_dport), 844 src, ntohs(th->th_sport)); 845 } 846 #endif 847 848 #ifdef INET6 849 static void 850 tcp6_log_refused(const struct ip6_hdr *ip6, const struct tcphdr *th) 851 { 852 char src[INET6_ADDRSTRLEN]; 853 char dst[INET6_ADDRSTRLEN]; 854 855 if (ip6) { 856 strlcpy(src, ip6_sprintf(&ip6->ip6_src), sizeof(src)); 857 strlcpy(dst, ip6_sprintf(&ip6->ip6_dst), sizeof(dst)); 858 } 859 else { 860 strlcpy(src, "(unknown v6)", sizeof(src)); 861 strlcpy(dst, "(unknown v6)", sizeof(dst)); 862 } 863 log(LOG_INFO, 864 "Connection attempt to TCP [%s]:%d from [%s]:%d\n", 865 dst, ntohs(th->th_dport), 866 src, ntohs(th->th_sport)); 867 } 868 #endif 869 870 /* 871 * Checksum extended TCP header and data. 872 */ 873 int 874 tcp_input_checksum(int af, struct mbuf *m, const struct tcphdr *th, 875 int toff, int off, int tlen) 876 { 877 878 /* 879 * XXX it's better to record and check if this mbuf is 880 * already checked. 881 */ 882 883 switch (af) { 884 #ifdef INET 885 case AF_INET: 886 switch (m->m_pkthdr.csum_flags & 887 ((m->m_pkthdr.rcvif->if_csum_flags_rx & M_CSUM_TCPv4) | 888 M_CSUM_TCP_UDP_BAD | M_CSUM_DATA)) { 889 case M_CSUM_TCPv4|M_CSUM_TCP_UDP_BAD: 890 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_bad); 891 goto badcsum; 892 893 case M_CSUM_TCPv4|M_CSUM_DATA: { 894 u_int32_t hw_csum = m->m_pkthdr.csum_data; 895 896 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_data); 897 if (m->m_pkthdr.csum_flags & M_CSUM_NO_PSEUDOHDR) { 898 const struct ip *ip = 899 mtod(m, const struct ip *); 900 901 hw_csum = in_cksum_phdr(ip->ip_src.s_addr, 902 ip->ip_dst.s_addr, 903 htons(hw_csum + tlen + off + IPPROTO_TCP)); 904 } 905 if ((hw_csum ^ 0xffff) != 0) 906 goto badcsum; 907 break; 908 } 909 910 case M_CSUM_TCPv4: 911 /* Checksum was okay. */ 912 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_ok); 913 break; 914 915 default: 916 /* 917 * Must compute it ourselves. Maybe skip checksum 918 * on loopback interfaces. 919 */ 920 if (__predict_true(!(m->m_pkthdr.rcvif->if_flags & 921 IFF_LOOPBACK) || 922 tcp_do_loopback_cksum)) { 923 TCP_CSUM_COUNTER_INCR(&tcp_swcsum); 924 if (in4_cksum(m, IPPROTO_TCP, toff, 925 tlen + off) != 0) 926 goto badcsum; 927 } 928 break; 929 } 930 break; 931 #endif /* INET4 */ 932 933 #ifdef INET6 934 case AF_INET6: 935 switch (m->m_pkthdr.csum_flags & 936 ((m->m_pkthdr.rcvif->if_csum_flags_rx & M_CSUM_TCPv6) | 937 M_CSUM_TCP_UDP_BAD | M_CSUM_DATA)) { 938 case M_CSUM_TCPv6|M_CSUM_TCP_UDP_BAD: 939 TCP_CSUM_COUNTER_INCR(&tcp6_hwcsum_bad); 940 goto badcsum; 941 942 #if 0 /* notyet */ 943 case M_CSUM_TCPv6|M_CSUM_DATA: 944 #endif 945 946 case M_CSUM_TCPv6: 947 /* Checksum was okay. */ 948 TCP_CSUM_COUNTER_INCR(&tcp6_hwcsum_ok); 949 break; 950 951 default: 952 /* 953 * Must compute it ourselves. Maybe skip checksum 954 * on loopback interfaces. 955 */ 956 if (__predict_true((m->m_flags & M_LOOP) == 0 || 957 tcp_do_loopback_cksum)) { 958 TCP_CSUM_COUNTER_INCR(&tcp6_swcsum); 959 if (in6_cksum(m, IPPROTO_TCP, toff, 960 tlen + off) != 0) 961 goto badcsum; 962 } 963 } 964 break; 965 #endif /* INET6 */ 966 } 967 968 return 0; 969 970 badcsum: 971 tcpstat.tcps_rcvbadsum++; 972 return -1; 973 } 974 975 /* 976 * TCP input routine, follows pages 65-76 of RFC 793 very closely. 977 */ 978 void 979 tcp_input(struct mbuf *m, ...) 980 { 981 struct tcphdr *th; 982 struct ip *ip; 983 struct inpcb *inp; 984 #ifdef INET6 985 struct ip6_hdr *ip6; 986 struct in6pcb *in6p; 987 #endif 988 u_int8_t *optp = NULL; 989 int optlen = 0; 990 int len, tlen, toff, hdroptlen = 0; 991 struct tcpcb *tp = 0; 992 int tiflags; 993 struct socket *so = NULL; 994 int todrop, dupseg, acked, ourfinisacked, needoutput = 0; 995 #ifdef TCP_DEBUG 996 short ostate = 0; 997 #endif 998 u_long tiwin; 999 struct tcp_opt_info opti; 1000 int off, iphlen; 1001 va_list ap; 1002 int af; /* af on the wire */ 1003 struct mbuf *tcp_saveti = NULL; 1004 uint32_t ts_rtt; 1005 uint8_t iptos; 1006 1007 MCLAIM(m, &tcp_rx_mowner); 1008 va_start(ap, m); 1009 toff = va_arg(ap, int); 1010 (void)va_arg(ap, int); /* ignore value, advance ap */ 1011 va_end(ap); 1012 1013 tcpstat.tcps_rcvtotal++; 1014 1015 bzero(&opti, sizeof(opti)); 1016 opti.ts_present = 0; 1017 opti.maxseg = 0; 1018 1019 /* 1020 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN. 1021 * 1022 * TCP is, by definition, unicast, so we reject all 1023 * multicast outright. 1024 * 1025 * Note, there are additional src/dst address checks in 1026 * the AF-specific code below. 1027 */ 1028 if (m->m_flags & (M_BCAST|M_MCAST)) { 1029 /* XXX stat */ 1030 goto drop; 1031 } 1032 #ifdef INET6 1033 if (m->m_flags & M_ANYCAST6) { 1034 /* XXX stat */ 1035 goto drop; 1036 } 1037 #endif 1038 1039 /* 1040 * Get IP and TCP header. 1041 * Note: IP leaves IP header in first mbuf. 1042 */ 1043 ip = mtod(m, struct ip *); 1044 #ifdef INET6 1045 ip6 = NULL; 1046 #endif 1047 switch (ip->ip_v) { 1048 #ifdef INET 1049 case 4: 1050 af = AF_INET; 1051 iphlen = sizeof(struct ip); 1052 ip = mtod(m, struct ip *); 1053 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, 1054 sizeof(struct tcphdr)); 1055 if (th == NULL) { 1056 tcpstat.tcps_rcvshort++; 1057 return; 1058 } 1059 /* We do the checksum after PCB lookup... */ 1060 len = ntohs(ip->ip_len); 1061 tlen = len - toff; 1062 iptos = ip->ip_tos; 1063 break; 1064 #endif 1065 #ifdef INET6 1066 case 6: 1067 ip = NULL; 1068 iphlen = sizeof(struct ip6_hdr); 1069 af = AF_INET6; 1070 ip6 = mtod(m, struct ip6_hdr *); 1071 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, 1072 sizeof(struct tcphdr)); 1073 if (th == NULL) { 1074 tcpstat.tcps_rcvshort++; 1075 return; 1076 } 1077 1078 /* Be proactive about malicious use of IPv4 mapped address */ 1079 if (IN6_IS_ADDR_V4MAPPED(&ip6->ip6_src) || 1080 IN6_IS_ADDR_V4MAPPED(&ip6->ip6_dst)) { 1081 /* XXX stat */ 1082 goto drop; 1083 } 1084 1085 /* 1086 * Be proactive about unspecified IPv6 address in source. 1087 * As we use all-zero to indicate unbounded/unconnected pcb, 1088 * unspecified IPv6 address can be used to confuse us. 1089 * 1090 * Note that packets with unspecified IPv6 destination is 1091 * already dropped in ip6_input. 1092 */ 1093 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 1094 /* XXX stat */ 1095 goto drop; 1096 } 1097 1098 /* 1099 * Make sure destination address is not multicast. 1100 * Source address checked in ip6_input(). 1101 */ 1102 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) { 1103 /* XXX stat */ 1104 goto drop; 1105 } 1106 1107 /* We do the checksum after PCB lookup... */ 1108 len = m->m_pkthdr.len; 1109 tlen = len - toff; 1110 iptos = (ntohl(ip6->ip6_flow) >> 20) & 0xff; 1111 break; 1112 #endif 1113 default: 1114 m_freem(m); 1115 return; 1116 } 1117 1118 KASSERT(TCP_HDR_ALIGNED_P(th)); 1119 1120 /* 1121 * Check that TCP offset makes sense, 1122 * pull out TCP options and adjust length. XXX 1123 */ 1124 off = th->th_off << 2; 1125 if (off < sizeof (struct tcphdr) || off > tlen) { 1126 tcpstat.tcps_rcvbadoff++; 1127 goto drop; 1128 } 1129 tlen -= off; 1130 1131 /* 1132 * tcp_input() has been modified to use tlen to mean the TCP data 1133 * length throughout the function. Other functions can use 1134 * m->m_pkthdr.len as the basis for calculating the TCP data length. 1135 * rja 1136 */ 1137 1138 if (off > sizeof (struct tcphdr)) { 1139 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, off); 1140 if (th == NULL) { 1141 tcpstat.tcps_rcvshort++; 1142 return; 1143 } 1144 /* 1145 * NOTE: ip/ip6 will not be affected by m_pulldown() 1146 * (as they're before toff) and we don't need to update those. 1147 */ 1148 KASSERT(TCP_HDR_ALIGNED_P(th)); 1149 optlen = off - sizeof (struct tcphdr); 1150 optp = ((u_int8_t *)th) + sizeof(struct tcphdr); 1151 /* 1152 * Do quick retrieval of timestamp options ("options 1153 * prediction?"). If timestamp is the only option and it's 1154 * formatted as recommended in RFC 1323 appendix A, we 1155 * quickly get the values now and not bother calling 1156 * tcp_dooptions(), etc. 1157 */ 1158 if ((optlen == TCPOLEN_TSTAMP_APPA || 1159 (optlen > TCPOLEN_TSTAMP_APPA && 1160 optp[TCPOLEN_TSTAMP_APPA] == TCPOPT_EOL)) && 1161 *(u_int32_t *)optp == htonl(TCPOPT_TSTAMP_HDR) && 1162 (th->th_flags & TH_SYN) == 0) { 1163 opti.ts_present = 1; 1164 opti.ts_val = ntohl(*(u_int32_t *)(optp + 4)); 1165 opti.ts_ecr = ntohl(*(u_int32_t *)(optp + 8)); 1166 optp = NULL; /* we've parsed the options */ 1167 } 1168 } 1169 tiflags = th->th_flags; 1170 1171 /* 1172 * Locate pcb for segment. 1173 */ 1174 findpcb: 1175 inp = NULL; 1176 #ifdef INET6 1177 in6p = NULL; 1178 #endif 1179 switch (af) { 1180 #ifdef INET 1181 case AF_INET: 1182 inp = in_pcblookup_connect(&tcbtable, ip->ip_src, th->th_sport, 1183 ip->ip_dst, th->th_dport); 1184 if (inp == 0) { 1185 ++tcpstat.tcps_pcbhashmiss; 1186 inp = in_pcblookup_bind(&tcbtable, ip->ip_dst, th->th_dport); 1187 } 1188 #ifdef INET6 1189 if (inp == 0) { 1190 struct in6_addr s, d; 1191 1192 /* mapped addr case */ 1193 bzero(&s, sizeof(s)); 1194 s.s6_addr16[5] = htons(0xffff); 1195 bcopy(&ip->ip_src, &s.s6_addr32[3], sizeof(ip->ip_src)); 1196 bzero(&d, sizeof(d)); 1197 d.s6_addr16[5] = htons(0xffff); 1198 bcopy(&ip->ip_dst, &d.s6_addr32[3], sizeof(ip->ip_dst)); 1199 in6p = in6_pcblookup_connect(&tcbtable, &s, 1200 th->th_sport, &d, th->th_dport, 0); 1201 if (in6p == 0) { 1202 ++tcpstat.tcps_pcbhashmiss; 1203 in6p = in6_pcblookup_bind(&tcbtable, &d, 1204 th->th_dport, 0); 1205 } 1206 } 1207 #endif 1208 #ifndef INET6 1209 if (inp == 0) 1210 #else 1211 if (inp == 0 && in6p == 0) 1212 #endif 1213 { 1214 ++tcpstat.tcps_noport; 1215 if (tcp_log_refused && 1216 (tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) { 1217 tcp4_log_refused(ip, th); 1218 } 1219 TCP_FIELDS_TO_HOST(th); 1220 goto dropwithreset_ratelim; 1221 } 1222 #if defined(IPSEC) || defined(FAST_IPSEC) 1223 if (inp && (inp->inp_socket->so_options & SO_ACCEPTCONN) == 0 && 1224 ipsec4_in_reject(m, inp)) { 1225 ipsecstat.in_polvio++; 1226 goto drop; 1227 } 1228 #ifdef INET6 1229 else if (in6p && 1230 (in6p->in6p_socket->so_options & SO_ACCEPTCONN) == 0 && 1231 ipsec6_in_reject_so(m, in6p->in6p_socket)) { 1232 ipsecstat.in_polvio++; 1233 goto drop; 1234 } 1235 #endif 1236 #endif /*IPSEC*/ 1237 break; 1238 #endif /*INET*/ 1239 #ifdef INET6 1240 case AF_INET6: 1241 { 1242 int faith; 1243 1244 #if defined(NFAITH) && NFAITH > 0 1245 faith = faithprefix(&ip6->ip6_dst); 1246 #else 1247 faith = 0; 1248 #endif 1249 in6p = in6_pcblookup_connect(&tcbtable, &ip6->ip6_src, 1250 th->th_sport, &ip6->ip6_dst, th->th_dport, faith); 1251 if (in6p == NULL) { 1252 ++tcpstat.tcps_pcbhashmiss; 1253 in6p = in6_pcblookup_bind(&tcbtable, &ip6->ip6_dst, 1254 th->th_dport, faith); 1255 } 1256 if (in6p == NULL) { 1257 ++tcpstat.tcps_noport; 1258 if (tcp_log_refused && 1259 (tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) { 1260 tcp6_log_refused(ip6, th); 1261 } 1262 TCP_FIELDS_TO_HOST(th); 1263 goto dropwithreset_ratelim; 1264 } 1265 #if defined(IPSEC) || defined(FAST_IPSEC) 1266 if ((in6p->in6p_socket->so_options & SO_ACCEPTCONN) == 0 && 1267 ipsec6_in_reject(m, in6p)) { 1268 ipsec6stat.in_polvio++; 1269 goto drop; 1270 } 1271 #endif /*IPSEC*/ 1272 break; 1273 } 1274 #endif 1275 } 1276 1277 /* 1278 * If the state is CLOSED (i.e., TCB does not exist) then 1279 * all data in the incoming segment is discarded. 1280 * If the TCB exists but is in CLOSED state, it is embryonic, 1281 * but should either do a listen or a connect soon. 1282 */ 1283 tp = NULL; 1284 so = NULL; 1285 if (inp) { 1286 tp = intotcpcb(inp); 1287 so = inp->inp_socket; 1288 } 1289 #ifdef INET6 1290 else if (in6p) { 1291 tp = in6totcpcb(in6p); 1292 so = in6p->in6p_socket; 1293 } 1294 #endif 1295 if (tp == 0) { 1296 TCP_FIELDS_TO_HOST(th); 1297 goto dropwithreset_ratelim; 1298 } 1299 if (tp->t_state == TCPS_CLOSED) 1300 goto drop; 1301 1302 /* 1303 * Checksum extended TCP header and data. 1304 */ 1305 if (tcp_input_checksum(af, m, th, toff, off, tlen)) 1306 goto badcsum; 1307 1308 TCP_FIELDS_TO_HOST(th); 1309 1310 /* Unscale the window into a 32-bit value. */ 1311 if ((tiflags & TH_SYN) == 0) 1312 tiwin = th->th_win << tp->snd_scale; 1313 else 1314 tiwin = th->th_win; 1315 1316 #ifdef INET6 1317 /* save packet options if user wanted */ 1318 if (in6p && (in6p->in6p_flags & IN6P_CONTROLOPTS)) { 1319 if (in6p->in6p_options) { 1320 m_freem(in6p->in6p_options); 1321 in6p->in6p_options = 0; 1322 } 1323 KASSERT(ip6 != NULL); 1324 ip6_savecontrol(in6p, &in6p->in6p_options, ip6, m); 1325 } 1326 #endif 1327 1328 if (so->so_options & (SO_DEBUG|SO_ACCEPTCONN)) { 1329 union syn_cache_sa src; 1330 union syn_cache_sa dst; 1331 1332 bzero(&src, sizeof(src)); 1333 bzero(&dst, sizeof(dst)); 1334 switch (af) { 1335 #ifdef INET 1336 case AF_INET: 1337 src.sin.sin_len = sizeof(struct sockaddr_in); 1338 src.sin.sin_family = AF_INET; 1339 src.sin.sin_addr = ip->ip_src; 1340 src.sin.sin_port = th->th_sport; 1341 1342 dst.sin.sin_len = sizeof(struct sockaddr_in); 1343 dst.sin.sin_family = AF_INET; 1344 dst.sin.sin_addr = ip->ip_dst; 1345 dst.sin.sin_port = th->th_dport; 1346 break; 1347 #endif 1348 #ifdef INET6 1349 case AF_INET6: 1350 src.sin6.sin6_len = sizeof(struct sockaddr_in6); 1351 src.sin6.sin6_family = AF_INET6; 1352 src.sin6.sin6_addr = ip6->ip6_src; 1353 src.sin6.sin6_port = th->th_sport; 1354 1355 dst.sin6.sin6_len = sizeof(struct sockaddr_in6); 1356 dst.sin6.sin6_family = AF_INET6; 1357 dst.sin6.sin6_addr = ip6->ip6_dst; 1358 dst.sin6.sin6_port = th->th_dport; 1359 break; 1360 #endif /* INET6 */ 1361 default: 1362 goto badsyn; /*sanity*/ 1363 } 1364 1365 if (so->so_options & SO_DEBUG) { 1366 #ifdef TCP_DEBUG 1367 ostate = tp->t_state; 1368 #endif 1369 1370 tcp_saveti = NULL; 1371 if (iphlen + sizeof(struct tcphdr) > MHLEN) 1372 goto nosave; 1373 1374 if (m->m_len > iphlen && (m->m_flags & M_EXT) == 0) { 1375 tcp_saveti = m_copym(m, 0, iphlen, M_DONTWAIT); 1376 if (!tcp_saveti) 1377 goto nosave; 1378 } else { 1379 MGETHDR(tcp_saveti, M_DONTWAIT, MT_HEADER); 1380 if (!tcp_saveti) 1381 goto nosave; 1382 MCLAIM(m, &tcp_mowner); 1383 tcp_saveti->m_len = iphlen; 1384 m_copydata(m, 0, iphlen, 1385 mtod(tcp_saveti, void *)); 1386 } 1387 1388 if (M_TRAILINGSPACE(tcp_saveti) < sizeof(struct tcphdr)) { 1389 m_freem(tcp_saveti); 1390 tcp_saveti = NULL; 1391 } else { 1392 tcp_saveti->m_len += sizeof(struct tcphdr); 1393 memcpy(mtod(tcp_saveti, char *) + iphlen, th, 1394 sizeof(struct tcphdr)); 1395 } 1396 nosave:; 1397 } 1398 if (so->so_options & SO_ACCEPTCONN) { 1399 if ((tiflags & (TH_RST|TH_ACK|TH_SYN)) != TH_SYN) { 1400 if (tiflags & TH_RST) { 1401 syn_cache_reset(&src.sa, &dst.sa, th); 1402 } else if ((tiflags & (TH_ACK|TH_SYN)) == 1403 (TH_ACK|TH_SYN)) { 1404 /* 1405 * Received a SYN,ACK. This should 1406 * never happen while we are in 1407 * LISTEN. Send an RST. 1408 */ 1409 goto badsyn; 1410 } else if (tiflags & TH_ACK) { 1411 so = syn_cache_get(&src.sa, &dst.sa, 1412 th, toff, tlen, so, m); 1413 if (so == NULL) { 1414 /* 1415 * We don't have a SYN for 1416 * this ACK; send an RST. 1417 */ 1418 goto badsyn; 1419 } else if (so == 1420 (struct socket *)(-1)) { 1421 /* 1422 * We were unable to create 1423 * the connection. If the 1424 * 3-way handshake was 1425 * completed, and RST has 1426 * been sent to the peer. 1427 * Since the mbuf might be 1428 * in use for the reply, 1429 * do not free it. 1430 */ 1431 m = NULL; 1432 } else { 1433 /* 1434 * We have created a 1435 * full-blown connection. 1436 */ 1437 tp = NULL; 1438 inp = NULL; 1439 #ifdef INET6 1440 in6p = NULL; 1441 #endif 1442 switch (so->so_proto->pr_domain->dom_family) { 1443 #ifdef INET 1444 case AF_INET: 1445 inp = sotoinpcb(so); 1446 tp = intotcpcb(inp); 1447 break; 1448 #endif 1449 #ifdef INET6 1450 case AF_INET6: 1451 in6p = sotoin6pcb(so); 1452 tp = in6totcpcb(in6p); 1453 break; 1454 #endif 1455 } 1456 if (tp == NULL) 1457 goto badsyn; /*XXX*/ 1458 tiwin <<= tp->snd_scale; 1459 goto after_listen; 1460 } 1461 } else { 1462 /* 1463 * None of RST, SYN or ACK was set. 1464 * This is an invalid packet for a 1465 * TCB in LISTEN state. Send a RST. 1466 */ 1467 goto badsyn; 1468 } 1469 } else { 1470 /* 1471 * Received a SYN. 1472 * 1473 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN 1474 */ 1475 if (m->m_flags & (M_BCAST|M_MCAST)) 1476 goto drop; 1477 1478 switch (af) { 1479 #ifdef INET6 1480 case AF_INET6: 1481 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) 1482 goto drop; 1483 break; 1484 #endif /* INET6 */ 1485 case AF_INET: 1486 if (IN_MULTICAST(ip->ip_dst.s_addr) || 1487 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 1488 goto drop; 1489 break; 1490 } 1491 1492 #ifdef INET6 1493 /* 1494 * If deprecated address is forbidden, we do 1495 * not accept SYN to deprecated interface 1496 * address to prevent any new inbound 1497 * connection from getting established. 1498 * When we do not accept SYN, we send a TCP 1499 * RST, with deprecated source address (instead 1500 * of dropping it). We compromise it as it is 1501 * much better for peer to send a RST, and 1502 * RST will be the final packet for the 1503 * exchange. 1504 * 1505 * If we do not forbid deprecated addresses, we 1506 * accept the SYN packet. RFC2462 does not 1507 * suggest dropping SYN in this case. 1508 * If we decipher RFC2462 5.5.4, it says like 1509 * this: 1510 * 1. use of deprecated addr with existing 1511 * communication is okay - "SHOULD continue 1512 * to be used" 1513 * 2. use of it with new communication: 1514 * (2a) "SHOULD NOT be used if alternate 1515 * address with sufficient scope is 1516 * available" 1517 * (2b) nothing mentioned otherwise. 1518 * Here we fall into (2b) case as we have no 1519 * choice in our source address selection - we 1520 * must obey the peer. 1521 * 1522 * The wording in RFC2462 is confusing, and 1523 * there are multiple description text for 1524 * deprecated address handling - worse, they 1525 * are not exactly the same. I believe 5.5.4 1526 * is the best one, so we follow 5.5.4. 1527 */ 1528 if (af == AF_INET6 && !ip6_use_deprecated) { 1529 struct in6_ifaddr *ia6; 1530 if ((ia6 = in6ifa_ifpwithaddr(m->m_pkthdr.rcvif, 1531 &ip6->ip6_dst)) && 1532 (ia6->ia6_flags & IN6_IFF_DEPRECATED)) { 1533 tp = NULL; 1534 goto dropwithreset; 1535 } 1536 } 1537 #endif 1538 1539 #if defined(IPSEC) || defined(FAST_IPSEC) 1540 switch (af) { 1541 #ifdef INET 1542 case AF_INET: 1543 if (ipsec4_in_reject_so(m, so)) { 1544 ipsecstat.in_polvio++; 1545 tp = NULL; 1546 goto dropwithreset; 1547 } 1548 break; 1549 #endif 1550 #ifdef INET6 1551 case AF_INET6: 1552 if (ipsec6_in_reject_so(m, so)) { 1553 ipsec6stat.in_polvio++; 1554 tp = NULL; 1555 goto dropwithreset; 1556 } 1557 break; 1558 #endif /*INET6*/ 1559 } 1560 #endif /*IPSEC*/ 1561 1562 /* 1563 * LISTEN socket received a SYN 1564 * from itself? This can't possibly 1565 * be valid; drop the packet. 1566 */ 1567 if (th->th_sport == th->th_dport) { 1568 int i; 1569 1570 switch (af) { 1571 #ifdef INET 1572 case AF_INET: 1573 i = in_hosteq(ip->ip_src, ip->ip_dst); 1574 break; 1575 #endif 1576 #ifdef INET6 1577 case AF_INET6: 1578 i = IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &ip6->ip6_dst); 1579 break; 1580 #endif 1581 default: 1582 i = 1; 1583 } 1584 if (i) { 1585 tcpstat.tcps_badsyn++; 1586 goto drop; 1587 } 1588 } 1589 1590 /* 1591 * SYN looks ok; create compressed TCP 1592 * state for it. 1593 */ 1594 if (so->so_qlen <= so->so_qlimit && 1595 syn_cache_add(&src.sa, &dst.sa, th, tlen, 1596 so, m, optp, optlen, &opti)) 1597 m = NULL; 1598 } 1599 goto drop; 1600 } 1601 } 1602 1603 after_listen: 1604 #ifdef DIAGNOSTIC 1605 /* 1606 * Should not happen now that all embryonic connections 1607 * are handled with compressed state. 1608 */ 1609 if (tp->t_state == TCPS_LISTEN) 1610 panic("tcp_input: TCPS_LISTEN"); 1611 #endif 1612 1613 /* 1614 * Segment received on connection. 1615 * Reset idle time and keep-alive timer. 1616 */ 1617 tp->t_rcvtime = tcp_now; 1618 if (TCPS_HAVEESTABLISHED(tp->t_state)) 1619 TCP_TIMER_ARM(tp, TCPT_KEEP, tp->t_keepidle); 1620 1621 /* 1622 * Process options. 1623 */ 1624 #ifdef TCP_SIGNATURE 1625 if (optp || (tp->t_flags & TF_SIGNATURE)) 1626 #else 1627 if (optp) 1628 #endif 1629 if (tcp_dooptions(tp, optp, optlen, th, m, toff, &opti) < 0) 1630 goto drop; 1631 1632 if (TCP_SACK_ENABLED(tp)) { 1633 tcp_del_sackholes(tp, th); 1634 } 1635 1636 if (TCP_ECN_ALLOWED(tp)) { 1637 switch (iptos & IPTOS_ECN_MASK) { 1638 case IPTOS_ECN_CE: 1639 tp->t_flags |= TF_ECN_SND_ECE; 1640 tcpstat.tcps_ecn_ce++; 1641 break; 1642 case IPTOS_ECN_ECT0: 1643 tcpstat.tcps_ecn_ect++; 1644 break; 1645 case IPTOS_ECN_ECT1: 1646 /* XXX: ignore for now -- rpaulo */ 1647 break; 1648 } 1649 1650 if (tiflags & TH_CWR) 1651 tp->t_flags &= ~TF_ECN_SND_ECE; 1652 1653 /* 1654 * Congestion experienced. 1655 * Ignore if we are already trying to recover. 1656 */ 1657 if ((tiflags & TH_ECE) && SEQ_GEQ(tp->snd_una, tp->snd_recover)) 1658 tp->t_congctl->cong_exp(tp); 1659 } 1660 1661 if (opti.ts_present && opti.ts_ecr) { 1662 /* 1663 * Calculate the RTT from the returned time stamp and the 1664 * connection's time base. If the time stamp is later than 1665 * the current time, or is extremely old, fall back to non-1323 1666 * RTT calculation. Since ts_ecr is unsigned, we can test both 1667 * at the same time. 1668 */ 1669 ts_rtt = TCP_TIMESTAMP(tp) - opti.ts_ecr + 1; 1670 if (ts_rtt > TCP_PAWS_IDLE) 1671 ts_rtt = 0; 1672 } else { 1673 ts_rtt = 0; 1674 } 1675 1676 /* 1677 * Header prediction: check for the two common cases 1678 * of a uni-directional data xfer. If the packet has 1679 * no control flags, is in-sequence, the window didn't 1680 * change and we're not retransmitting, it's a 1681 * candidate. If the length is zero and the ack moved 1682 * forward, we're the sender side of the xfer. Just 1683 * free the data acked & wake any higher level process 1684 * that was blocked waiting for space. If the length 1685 * is non-zero and the ack didn't move, we're the 1686 * receiver side. If we're getting packets in-order 1687 * (the reassembly queue is empty), add the data to 1688 * the socket buffer and note that we need a delayed ack. 1689 */ 1690 if (tp->t_state == TCPS_ESTABLISHED && 1691 (tiflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ECE|TH_CWR|TH_ACK)) 1692 == TH_ACK && 1693 (!opti.ts_present || TSTMP_GEQ(opti.ts_val, tp->ts_recent)) && 1694 th->th_seq == tp->rcv_nxt && 1695 tiwin && tiwin == tp->snd_wnd && 1696 tp->snd_nxt == tp->snd_max) { 1697 1698 /* 1699 * If last ACK falls within this segment's sequence numbers, 1700 * record the timestamp. 1701 * NOTE that the test is modified according to the latest 1702 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 1703 * 1704 * note that we already know 1705 * TSTMP_GEQ(opti.ts_val, tp->ts_recent) 1706 */ 1707 if (opti.ts_present && 1708 SEQ_LEQ(th->th_seq, tp->last_ack_sent)) { 1709 tp->ts_recent_age = tcp_now; 1710 tp->ts_recent = opti.ts_val; 1711 } 1712 1713 if (tlen == 0) { 1714 /* Ack prediction. */ 1715 if (SEQ_GT(th->th_ack, tp->snd_una) && 1716 SEQ_LEQ(th->th_ack, tp->snd_max) && 1717 tp->snd_cwnd >= tp->snd_wnd && 1718 tp->t_partialacks < 0) { 1719 /* 1720 * this is a pure ack for outstanding data. 1721 */ 1722 ++tcpstat.tcps_predack; 1723 if (ts_rtt) 1724 tcp_xmit_timer(tp, ts_rtt); 1725 else if (tp->t_rtttime && 1726 SEQ_GT(th->th_ack, tp->t_rtseq)) 1727 tcp_xmit_timer(tp, 1728 tcp_now - tp->t_rtttime); 1729 acked = th->th_ack - tp->snd_una; 1730 tcpstat.tcps_rcvackpack++; 1731 tcpstat.tcps_rcvackbyte += acked; 1732 nd6_hint(tp); 1733 1734 if (acked > (tp->t_lastoff - tp->t_inoff)) 1735 tp->t_lastm = NULL; 1736 sbdrop(&so->so_snd, acked); 1737 tp->t_lastoff -= acked; 1738 1739 ICMP_CHECK(tp, th, acked); 1740 1741 tp->snd_una = th->th_ack; 1742 tp->snd_fack = tp->snd_una; 1743 if (SEQ_LT(tp->snd_high, tp->snd_una)) 1744 tp->snd_high = tp->snd_una; 1745 m_freem(m); 1746 1747 /* 1748 * If all outstanding data are acked, stop 1749 * retransmit timer, otherwise restart timer 1750 * using current (possibly backed-off) value. 1751 * If process is waiting for space, 1752 * wakeup/selwakeup/signal. If data 1753 * are ready to send, let tcp_output 1754 * decide between more output or persist. 1755 */ 1756 if (tp->snd_una == tp->snd_max) 1757 TCP_TIMER_DISARM(tp, TCPT_REXMT); 1758 else if (TCP_TIMER_ISARMED(tp, 1759 TCPT_PERSIST) == 0) 1760 TCP_TIMER_ARM(tp, TCPT_REXMT, 1761 tp->t_rxtcur); 1762 1763 sowwakeup(so); 1764 if (so->so_snd.sb_cc) 1765 (void) tcp_output(tp); 1766 if (tcp_saveti) 1767 m_freem(tcp_saveti); 1768 return; 1769 } 1770 } else if (th->th_ack == tp->snd_una && 1771 TAILQ_FIRST(&tp->segq) == NULL && 1772 tlen <= sbspace(&so->so_rcv)) { 1773 int newsize = 0; /* automatic sockbuf scaling */ 1774 1775 /* 1776 * this is a pure, in-sequence data packet 1777 * with nothing on the reassembly queue and 1778 * we have enough buffer space to take it. 1779 */ 1780 ++tcpstat.tcps_preddat; 1781 tp->rcv_nxt += tlen; 1782 tcpstat.tcps_rcvpack++; 1783 tcpstat.tcps_rcvbyte += tlen; 1784 nd6_hint(tp); 1785 1786 /* 1787 * Automatic sizing enables the performance of large buffers 1788 * and most of the efficiency of small ones by only allocating 1789 * space when it is needed. 1790 * 1791 * On the receive side the socket buffer memory is only rarely 1792 * used to any significant extent. This allows us to be much 1793 * more aggressive in scaling the receive socket buffer. For 1794 * the case that the buffer space is actually used to a large 1795 * extent and we run out of kernel memory we can simply drop 1796 * the new segments; TCP on the sender will just retransmit it 1797 * later. Setting the buffer size too big may only consume too 1798 * much kernel memory if the application doesn't read() from 1799 * the socket or packet loss or reordering makes use of the 1800 * reassembly queue. 1801 * 1802 * The criteria to step up the receive buffer one notch are: 1803 * 1. the number of bytes received during the time it takes 1804 * one timestamp to be reflected back to us (the RTT); 1805 * 2. received bytes per RTT is within seven eighth of the 1806 * current socket buffer size; 1807 * 3. receive buffer size has not hit maximal automatic size; 1808 * 1809 * This algorithm does one step per RTT at most and only if 1810 * we receive a bulk stream w/o packet losses or reorderings. 1811 * Shrinking the buffer during idle times is not necessary as 1812 * it doesn't consume any memory when idle. 1813 * 1814 * TODO: Only step up if the application is actually serving 1815 * the buffer to better manage the socket buffer resources. 1816 */ 1817 if (tcp_do_autorcvbuf && 1818 opti.ts_ecr && 1819 (so->so_rcv.sb_flags & SB_AUTOSIZE)) { 1820 if (opti.ts_ecr > tp->rfbuf_ts && 1821 opti.ts_ecr - tp->rfbuf_ts < PR_SLOWHZ) { 1822 if (tp->rfbuf_cnt > 1823 (so->so_rcv.sb_hiwat / 8 * 7) && 1824 so->so_rcv.sb_hiwat < 1825 tcp_autorcvbuf_max) { 1826 newsize = 1827 min(so->so_rcv.sb_hiwat + 1828 tcp_autorcvbuf_inc, 1829 tcp_autorcvbuf_max); 1830 } 1831 /* Start over with next RTT. */ 1832 tp->rfbuf_ts = 0; 1833 tp->rfbuf_cnt = 0; 1834 } else 1835 tp->rfbuf_cnt += tlen; /* add up */ 1836 } 1837 1838 /* 1839 * Drop TCP, IP headers and TCP options then add data 1840 * to socket buffer. 1841 */ 1842 if (so->so_state & SS_CANTRCVMORE) 1843 m_freem(m); 1844 else { 1845 /* 1846 * Set new socket buffer size. 1847 * Give up when limit is reached. 1848 */ 1849 if (newsize) 1850 if (!sbreserve(&so->so_rcv, 1851 newsize, so)) 1852 so->so_rcv.sb_flags &= ~SB_AUTOSIZE; 1853 m_adj(m, toff + off); 1854 sbappendstream(&so->so_rcv, m); 1855 } 1856 sorwakeup(so); 1857 TCP_SETUP_ACK(tp, th); 1858 if (tp->t_flags & TF_ACKNOW) 1859 (void) tcp_output(tp); 1860 if (tcp_saveti) 1861 m_freem(tcp_saveti); 1862 return; 1863 } 1864 } 1865 1866 /* 1867 * Compute mbuf offset to TCP data segment. 1868 */ 1869 hdroptlen = toff + off; 1870 1871 /* 1872 * Calculate amount of space in receive window, 1873 * and then do TCP input processing. 1874 * Receive window is amount of space in rcv queue, 1875 * but not less than advertised window. 1876 */ 1877 { int win; 1878 1879 win = sbspace(&so->so_rcv); 1880 if (win < 0) 1881 win = 0; 1882 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 1883 } 1884 1885 /* Reset receive buffer auto scaling when not in bulk receive mode. */ 1886 tp->rfbuf_ts = 0; 1887 tp->rfbuf_cnt = 0; 1888 1889 switch (tp->t_state) { 1890 /* 1891 * If the state is SYN_SENT: 1892 * if seg contains an ACK, but not for our SYN, drop the input. 1893 * if seg contains a RST, then drop the connection. 1894 * if seg does not contain SYN, then drop it. 1895 * Otherwise this is an acceptable SYN segment 1896 * initialize tp->rcv_nxt and tp->irs 1897 * if seg contains ack then advance tp->snd_una 1898 * if seg contains a ECE and ECN support is enabled, the stream 1899 * is ECN capable. 1900 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 1901 * arrange for segment to be acked (eventually) 1902 * continue processing rest of data/controls, beginning with URG 1903 */ 1904 case TCPS_SYN_SENT: 1905 if ((tiflags & TH_ACK) && 1906 (SEQ_LEQ(th->th_ack, tp->iss) || 1907 SEQ_GT(th->th_ack, tp->snd_max))) 1908 goto dropwithreset; 1909 if (tiflags & TH_RST) { 1910 if (tiflags & TH_ACK) 1911 tp = tcp_drop(tp, ECONNREFUSED); 1912 goto drop; 1913 } 1914 if ((tiflags & TH_SYN) == 0) 1915 goto drop; 1916 if (tiflags & TH_ACK) { 1917 tp->snd_una = th->th_ack; 1918 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 1919 tp->snd_nxt = tp->snd_una; 1920 if (SEQ_LT(tp->snd_high, tp->snd_una)) 1921 tp->snd_high = tp->snd_una; 1922 TCP_TIMER_DISARM(tp, TCPT_REXMT); 1923 1924 if ((tiflags & TH_ECE) && tcp_do_ecn) { 1925 tp->t_flags |= TF_ECN_PERMIT; 1926 tcpstat.tcps_ecn_shs++; 1927 } 1928 1929 } 1930 tp->irs = th->th_seq; 1931 tcp_rcvseqinit(tp); 1932 tp->t_flags |= TF_ACKNOW; 1933 tcp_mss_from_peer(tp, opti.maxseg); 1934 1935 /* 1936 * Initialize the initial congestion window. If we 1937 * had to retransmit the SYN, we must initialize cwnd 1938 * to 1 segment (i.e. the Loss Window). 1939 */ 1940 if (tp->t_flags & TF_SYN_REXMT) 1941 tp->snd_cwnd = tp->t_peermss; 1942 else { 1943 int ss = tcp_init_win; 1944 #ifdef INET 1945 if (inp != NULL && in_localaddr(inp->inp_faddr)) 1946 ss = tcp_init_win_local; 1947 #endif 1948 #ifdef INET6 1949 if (in6p != NULL && in6_localaddr(&in6p->in6p_faddr)) 1950 ss = tcp_init_win_local; 1951 #endif 1952 tp->snd_cwnd = TCP_INITIAL_WINDOW(ss, tp->t_peermss); 1953 } 1954 1955 tcp_rmx_rtt(tp); 1956 if (tiflags & TH_ACK) { 1957 tcpstat.tcps_connects++; 1958 soisconnected(so); 1959 tcp_established(tp); 1960 /* Do window scaling on this connection? */ 1961 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 1962 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 1963 tp->snd_scale = tp->requested_s_scale; 1964 tp->rcv_scale = tp->request_r_scale; 1965 } 1966 TCP_REASS_LOCK(tp); 1967 (void) tcp_reass(tp, NULL, (struct mbuf *)0, &tlen); 1968 TCP_REASS_UNLOCK(tp); 1969 /* 1970 * if we didn't have to retransmit the SYN, 1971 * use its rtt as our initial srtt & rtt var. 1972 */ 1973 if (tp->t_rtttime) 1974 tcp_xmit_timer(tp, tcp_now - tp->t_rtttime); 1975 } else 1976 tp->t_state = TCPS_SYN_RECEIVED; 1977 1978 /* 1979 * Advance th->th_seq to correspond to first data byte. 1980 * If data, trim to stay within window, 1981 * dropping FIN if necessary. 1982 */ 1983 th->th_seq++; 1984 if (tlen > tp->rcv_wnd) { 1985 todrop = tlen - tp->rcv_wnd; 1986 m_adj(m, -todrop); 1987 tlen = tp->rcv_wnd; 1988 tiflags &= ~TH_FIN; 1989 tcpstat.tcps_rcvpackafterwin++; 1990 tcpstat.tcps_rcvbyteafterwin += todrop; 1991 } 1992 tp->snd_wl1 = th->th_seq - 1; 1993 tp->rcv_up = th->th_seq; 1994 goto step6; 1995 1996 /* 1997 * If the state is SYN_RECEIVED: 1998 * If seg contains an ACK, but not for our SYN, drop the input 1999 * and generate an RST. See page 36, rfc793 2000 */ 2001 case TCPS_SYN_RECEIVED: 2002 if ((tiflags & TH_ACK) && 2003 (SEQ_LEQ(th->th_ack, tp->iss) || 2004 SEQ_GT(th->th_ack, tp->snd_max))) 2005 goto dropwithreset; 2006 break; 2007 } 2008 2009 /* 2010 * States other than LISTEN or SYN_SENT. 2011 * First check timestamp, if present. 2012 * Then check that at least some bytes of segment are within 2013 * receive window. If segment begins before rcv_nxt, 2014 * drop leading data (and SYN); if nothing left, just ack. 2015 * 2016 * RFC 1323 PAWS: If we have a timestamp reply on this segment 2017 * and it's less than ts_recent, drop it. 2018 */ 2019 if (opti.ts_present && (tiflags & TH_RST) == 0 && tp->ts_recent && 2020 TSTMP_LT(opti.ts_val, tp->ts_recent)) { 2021 2022 /* Check to see if ts_recent is over 24 days old. */ 2023 if (tcp_now - tp->ts_recent_age > TCP_PAWS_IDLE) { 2024 /* 2025 * Invalidate ts_recent. If this segment updates 2026 * ts_recent, the age will be reset later and ts_recent 2027 * will get a valid value. If it does not, setting 2028 * ts_recent to zero will at least satisfy the 2029 * requirement that zero be placed in the timestamp 2030 * echo reply when ts_recent isn't valid. The 2031 * age isn't reset until we get a valid ts_recent 2032 * because we don't want out-of-order segments to be 2033 * dropped when ts_recent is old. 2034 */ 2035 tp->ts_recent = 0; 2036 } else { 2037 tcpstat.tcps_rcvduppack++; 2038 tcpstat.tcps_rcvdupbyte += tlen; 2039 tcpstat.tcps_pawsdrop++; 2040 tcp_new_dsack(tp, th->th_seq, tlen); 2041 goto dropafterack; 2042 } 2043 } 2044 2045 todrop = tp->rcv_nxt - th->th_seq; 2046 dupseg = false; 2047 if (todrop > 0) { 2048 if (tiflags & TH_SYN) { 2049 tiflags &= ~TH_SYN; 2050 th->th_seq++; 2051 if (th->th_urp > 1) 2052 th->th_urp--; 2053 else { 2054 tiflags &= ~TH_URG; 2055 th->th_urp = 0; 2056 } 2057 todrop--; 2058 } 2059 if (todrop > tlen || 2060 (todrop == tlen && (tiflags & TH_FIN) == 0)) { 2061 /* 2062 * Any valid FIN or RST must be to the left of the 2063 * window. At this point the FIN or RST must be a 2064 * duplicate or out of sequence; drop it. 2065 */ 2066 if (tiflags & TH_RST) 2067 goto drop; 2068 tiflags &= ~(TH_FIN|TH_RST); 2069 /* 2070 * Send an ACK to resynchronize and drop any data. 2071 * But keep on processing for RST or ACK. 2072 */ 2073 tp->t_flags |= TF_ACKNOW; 2074 todrop = tlen; 2075 dupseg = true; 2076 tcpstat.tcps_rcvdupbyte += todrop; 2077 tcpstat.tcps_rcvduppack++; 2078 } else if ((tiflags & TH_RST) && 2079 th->th_seq != tp->last_ack_sent) { 2080 /* 2081 * Test for reset before adjusting the sequence 2082 * number for overlapping data. 2083 */ 2084 goto dropafterack_ratelim; 2085 } else { 2086 tcpstat.tcps_rcvpartduppack++; 2087 tcpstat.tcps_rcvpartdupbyte += todrop; 2088 } 2089 tcp_new_dsack(tp, th->th_seq, todrop); 2090 hdroptlen += todrop; /*drop from head afterwards*/ 2091 th->th_seq += todrop; 2092 tlen -= todrop; 2093 if (th->th_urp > todrop) 2094 th->th_urp -= todrop; 2095 else { 2096 tiflags &= ~TH_URG; 2097 th->th_urp = 0; 2098 } 2099 } 2100 2101 /* 2102 * If new data are received on a connection after the 2103 * user processes are gone, then RST the other end. 2104 */ 2105 if ((so->so_state & SS_NOFDREF) && 2106 tp->t_state > TCPS_CLOSE_WAIT && tlen) { 2107 tp = tcp_close(tp); 2108 tcpstat.tcps_rcvafterclose++; 2109 goto dropwithreset; 2110 } 2111 2112 /* 2113 * If segment ends after window, drop trailing data 2114 * (and PUSH and FIN); if nothing left, just ACK. 2115 */ 2116 todrop = (th->th_seq + tlen) - (tp->rcv_nxt+tp->rcv_wnd); 2117 if (todrop > 0) { 2118 tcpstat.tcps_rcvpackafterwin++; 2119 if (todrop >= tlen) { 2120 /* 2121 * The segment actually starts after the window. 2122 * th->th_seq + tlen - tp->rcv_nxt - tp->rcv_wnd >= tlen 2123 * th->th_seq - tp->rcv_nxt - tp->rcv_wnd >= 0 2124 * th->th_seq >= tp->rcv_nxt + tp->rcv_wnd 2125 */ 2126 tcpstat.tcps_rcvbyteafterwin += tlen; 2127 /* 2128 * If a new connection request is received 2129 * while in TIME_WAIT, drop the old connection 2130 * and start over if the sequence numbers 2131 * are above the previous ones. 2132 * 2133 * NOTE: We will checksum the packet again, and 2134 * so we need to put the header fields back into 2135 * network order! 2136 * XXX This kind of sucks, but we don't expect 2137 * XXX this to happen very often, so maybe it 2138 * XXX doesn't matter so much. 2139 */ 2140 if (tiflags & TH_SYN && 2141 tp->t_state == TCPS_TIME_WAIT && 2142 SEQ_GT(th->th_seq, tp->rcv_nxt)) { 2143 tp = tcp_close(tp); 2144 TCP_FIELDS_TO_NET(th); 2145 goto findpcb; 2146 } 2147 /* 2148 * If window is closed can only take segments at 2149 * window edge, and have to drop data and PUSH from 2150 * incoming segments. Continue processing, but 2151 * remember to ack. Otherwise, drop segment 2152 * and (if not RST) ack. 2153 */ 2154 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 2155 tp->t_flags |= TF_ACKNOW; 2156 tcpstat.tcps_rcvwinprobe++; 2157 } else 2158 goto dropafterack; 2159 } else 2160 tcpstat.tcps_rcvbyteafterwin += todrop; 2161 m_adj(m, -todrop); 2162 tlen -= todrop; 2163 tiflags &= ~(TH_PUSH|TH_FIN); 2164 } 2165 2166 /* 2167 * If last ACK falls within this segment's sequence numbers, 2168 * record the timestamp. 2169 * NOTE: 2170 * 1) That the test incorporates suggestions from the latest 2171 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 2172 * 2) That updating only on newer timestamps interferes with 2173 * our earlier PAWS tests, so this check should be solely 2174 * predicated on the sequence space of this segment. 2175 * 3) That we modify the segment boundary check to be 2176 * Last.ACK.Sent <= SEG.SEQ + SEG.Len 2177 * instead of RFC1323's 2178 * Last.ACK.Sent < SEG.SEQ + SEG.Len, 2179 * This modified check allows us to overcome RFC1323's 2180 * limitations as described in Stevens TCP/IP Illustrated 2181 * Vol. 2 p.869. In such cases, we can still calculate the 2182 * RTT correctly when RCV.NXT == Last.ACK.Sent. 2183 */ 2184 if (opti.ts_present && 2185 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 2186 SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen + 2187 ((tiflags & (TH_SYN|TH_FIN)) != 0))) { 2188 tp->ts_recent_age = tcp_now; 2189 tp->ts_recent = opti.ts_val; 2190 } 2191 2192 /* 2193 * If the RST bit is set examine the state: 2194 * SYN_RECEIVED STATE: 2195 * If passive open, return to LISTEN state. 2196 * If active open, inform user that connection was refused. 2197 * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES: 2198 * Inform user that connection was reset, and close tcb. 2199 * CLOSING, LAST_ACK, TIME_WAIT STATES 2200 * Close the tcb. 2201 */ 2202 if (tiflags & TH_RST) { 2203 if (th->th_seq != tp->last_ack_sent) 2204 goto dropafterack_ratelim; 2205 2206 switch (tp->t_state) { 2207 case TCPS_SYN_RECEIVED: 2208 so->so_error = ECONNREFUSED; 2209 goto close; 2210 2211 case TCPS_ESTABLISHED: 2212 case TCPS_FIN_WAIT_1: 2213 case TCPS_FIN_WAIT_2: 2214 case TCPS_CLOSE_WAIT: 2215 so->so_error = ECONNRESET; 2216 close: 2217 tp->t_state = TCPS_CLOSED; 2218 tcpstat.tcps_drops++; 2219 tp = tcp_close(tp); 2220 goto drop; 2221 2222 case TCPS_CLOSING: 2223 case TCPS_LAST_ACK: 2224 case TCPS_TIME_WAIT: 2225 tp = tcp_close(tp); 2226 goto drop; 2227 } 2228 } 2229 2230 /* 2231 * Since we've covered the SYN-SENT and SYN-RECEIVED states above 2232 * we must be in a synchronized state. RFC791 states (under RST 2233 * generation) that any unacceptable segment (an out-of-order SYN 2234 * qualifies) received in a synchronized state must elicit only an 2235 * empty acknowledgment segment ... and the connection remains in 2236 * the same state. 2237 */ 2238 if (tiflags & TH_SYN) { 2239 if (tp->rcv_nxt == th->th_seq) { 2240 tcp_respond(tp, m, m, th, (tcp_seq)0, th->th_ack - 1, 2241 TH_ACK); 2242 if (tcp_saveti) 2243 m_freem(tcp_saveti); 2244 return; 2245 } 2246 2247 goto dropafterack_ratelim; 2248 } 2249 2250 /* 2251 * If the ACK bit is off we drop the segment and return. 2252 */ 2253 if ((tiflags & TH_ACK) == 0) { 2254 if (tp->t_flags & TF_ACKNOW) 2255 goto dropafterack; 2256 else 2257 goto drop; 2258 } 2259 2260 /* 2261 * Ack processing. 2262 */ 2263 switch (tp->t_state) { 2264 2265 /* 2266 * In SYN_RECEIVED state if the ack ACKs our SYN then enter 2267 * ESTABLISHED state and continue processing, otherwise 2268 * send an RST. 2269 */ 2270 case TCPS_SYN_RECEIVED: 2271 if (SEQ_GT(tp->snd_una, th->th_ack) || 2272 SEQ_GT(th->th_ack, tp->snd_max)) 2273 goto dropwithreset; 2274 tcpstat.tcps_connects++; 2275 soisconnected(so); 2276 tcp_established(tp); 2277 /* Do window scaling? */ 2278 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2279 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2280 tp->snd_scale = tp->requested_s_scale; 2281 tp->rcv_scale = tp->request_r_scale; 2282 } 2283 TCP_REASS_LOCK(tp); 2284 (void) tcp_reass(tp, NULL, (struct mbuf *)0, &tlen); 2285 TCP_REASS_UNLOCK(tp); 2286 tp->snd_wl1 = th->th_seq - 1; 2287 /* fall into ... */ 2288 2289 /* 2290 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 2291 * ACKs. If the ack is in the range 2292 * tp->snd_una < th->th_ack <= tp->snd_max 2293 * then advance tp->snd_una to th->th_ack and drop 2294 * data from the retransmission queue. If this ACK reflects 2295 * more up to date window information we update our window information. 2296 */ 2297 case TCPS_ESTABLISHED: 2298 case TCPS_FIN_WAIT_1: 2299 case TCPS_FIN_WAIT_2: 2300 case TCPS_CLOSE_WAIT: 2301 case TCPS_CLOSING: 2302 case TCPS_LAST_ACK: 2303 case TCPS_TIME_WAIT: 2304 2305 if (SEQ_LEQ(th->th_ack, tp->snd_una)) { 2306 if (tlen == 0 && !dupseg && tiwin == tp->snd_wnd) { 2307 tcpstat.tcps_rcvdupack++; 2308 /* 2309 * If we have outstanding data (other than 2310 * a window probe), this is a completely 2311 * duplicate ack (ie, window info didn't 2312 * change), the ack is the biggest we've 2313 * seen and we've seen exactly our rexmt 2314 * threshhold of them, assume a packet 2315 * has been dropped and retransmit it. 2316 * Kludge snd_nxt & the congestion 2317 * window so we send only this one 2318 * packet. 2319 */ 2320 if (TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 || 2321 th->th_ack != tp->snd_una) 2322 tp->t_dupacks = 0; 2323 else if (tp->t_partialacks < 0 && 2324 (++tp->t_dupacks == tcprexmtthresh || 2325 TCP_FACK_FASTRECOV(tp))) { 2326 /* 2327 * Do the fast retransmit, and adjust 2328 * congestion control paramenters. 2329 */ 2330 if (tp->t_congctl->fast_retransmit(tp, th)) { 2331 /* False fast retransmit */ 2332 break; 2333 } else 2334 goto drop; 2335 } else if (tp->t_dupacks > tcprexmtthresh) { 2336 tp->snd_cwnd += tp->t_segsz; 2337 (void) tcp_output(tp); 2338 goto drop; 2339 } 2340 } else { 2341 /* 2342 * If the ack appears to be very old, only 2343 * allow data that is in-sequence. This 2344 * makes it somewhat more difficult to insert 2345 * forged data by guessing sequence numbers. 2346 * Sent an ack to try to update the send 2347 * sequence number on the other side. 2348 */ 2349 if (tlen && th->th_seq != tp->rcv_nxt && 2350 SEQ_LT(th->th_ack, 2351 tp->snd_una - tp->max_sndwnd)) 2352 goto dropafterack; 2353 } 2354 break; 2355 } 2356 /* 2357 * If the congestion window was inflated to account 2358 * for the other side's cached packets, retract it. 2359 */ 2360 /* XXX: make SACK have his own congestion control 2361 * struct -- rpaulo */ 2362 if (TCP_SACK_ENABLED(tp)) 2363 tcp_sack_newack(tp, th); 2364 else 2365 tp->t_congctl->fast_retransmit_newack(tp, th); 2366 if (SEQ_GT(th->th_ack, tp->snd_max)) { 2367 tcpstat.tcps_rcvacktoomuch++; 2368 goto dropafterack; 2369 } 2370 acked = th->th_ack - tp->snd_una; 2371 tcpstat.tcps_rcvackpack++; 2372 tcpstat.tcps_rcvackbyte += acked; 2373 2374 /* 2375 * If we have a timestamp reply, update smoothed 2376 * round trip time. If no timestamp is present but 2377 * transmit timer is running and timed sequence 2378 * number was acked, update smoothed round trip time. 2379 * Since we now have an rtt measurement, cancel the 2380 * timer backoff (cf., Phil Karn's retransmit alg.). 2381 * Recompute the initial retransmit timer. 2382 */ 2383 if (ts_rtt) 2384 tcp_xmit_timer(tp, ts_rtt); 2385 else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) 2386 tcp_xmit_timer(tp, tcp_now - tp->t_rtttime); 2387 2388 /* 2389 * If all outstanding data is acked, stop retransmit 2390 * timer and remember to restart (more output or persist). 2391 * If there is more data to be acked, restart retransmit 2392 * timer, using current (possibly backed-off) value. 2393 */ 2394 if (th->th_ack == tp->snd_max) { 2395 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2396 needoutput = 1; 2397 } else if (TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) 2398 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 2399 2400 /* 2401 * New data has been acked, adjust the congestion window. 2402 */ 2403 tp->t_congctl->newack(tp, th); 2404 2405 nd6_hint(tp); 2406 if (acked > so->so_snd.sb_cc) { 2407 tp->snd_wnd -= so->so_snd.sb_cc; 2408 sbdrop(&so->so_snd, (int)so->so_snd.sb_cc); 2409 ourfinisacked = 1; 2410 } else { 2411 if (acked > (tp->t_lastoff - tp->t_inoff)) 2412 tp->t_lastm = NULL; 2413 sbdrop(&so->so_snd, acked); 2414 tp->t_lastoff -= acked; 2415 tp->snd_wnd -= acked; 2416 ourfinisacked = 0; 2417 } 2418 sowwakeup(so); 2419 2420 ICMP_CHECK(tp, th, acked); 2421 2422 tp->snd_una = th->th_ack; 2423 if (SEQ_GT(tp->snd_una, tp->snd_fack)) 2424 tp->snd_fack = tp->snd_una; 2425 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2426 tp->snd_nxt = tp->snd_una; 2427 if (SEQ_LT(tp->snd_high, tp->snd_una)) 2428 tp->snd_high = tp->snd_una; 2429 2430 switch (tp->t_state) { 2431 2432 /* 2433 * In FIN_WAIT_1 STATE in addition to the processing 2434 * for the ESTABLISHED state if our FIN is now acknowledged 2435 * then enter FIN_WAIT_2. 2436 */ 2437 case TCPS_FIN_WAIT_1: 2438 if (ourfinisacked) { 2439 /* 2440 * If we can't receive any more 2441 * data, then closing user can proceed. 2442 * Starting the timer is contrary to the 2443 * specification, but if we don't get a FIN 2444 * we'll hang forever. 2445 */ 2446 if (so->so_state & SS_CANTRCVMORE) { 2447 soisdisconnected(so); 2448 if (tp->t_maxidle > 0) 2449 TCP_TIMER_ARM(tp, TCPT_2MSL, 2450 tp->t_maxidle); 2451 } 2452 tp->t_state = TCPS_FIN_WAIT_2; 2453 } 2454 break; 2455 2456 /* 2457 * In CLOSING STATE in addition to the processing for 2458 * the ESTABLISHED state if the ACK acknowledges our FIN 2459 * then enter the TIME-WAIT state, otherwise ignore 2460 * the segment. 2461 */ 2462 case TCPS_CLOSING: 2463 if (ourfinisacked) { 2464 tp->t_state = TCPS_TIME_WAIT; 2465 tcp_canceltimers(tp); 2466 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 2467 soisdisconnected(so); 2468 } 2469 break; 2470 2471 /* 2472 * In LAST_ACK, we may still be waiting for data to drain 2473 * and/or to be acked, as well as for the ack of our FIN. 2474 * If our FIN is now acknowledged, delete the TCB, 2475 * enter the closed state and return. 2476 */ 2477 case TCPS_LAST_ACK: 2478 if (ourfinisacked) { 2479 tp = tcp_close(tp); 2480 goto drop; 2481 } 2482 break; 2483 2484 /* 2485 * In TIME_WAIT state the only thing that should arrive 2486 * is a retransmission of the remote FIN. Acknowledge 2487 * it and restart the finack timer. 2488 */ 2489 case TCPS_TIME_WAIT: 2490 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 2491 goto dropafterack; 2492 } 2493 } 2494 2495 step6: 2496 /* 2497 * Update window information. 2498 * Don't look at window if no ACK: TAC's send garbage on first SYN. 2499 */ 2500 if ((tiflags & TH_ACK) && (SEQ_LT(tp->snd_wl1, th->th_seq) || 2501 (tp->snd_wl1 == th->th_seq && (SEQ_LT(tp->snd_wl2, th->th_ack) || 2502 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))) { 2503 /* keep track of pure window updates */ 2504 if (tlen == 0 && 2505 tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) 2506 tcpstat.tcps_rcvwinupd++; 2507 tp->snd_wnd = tiwin; 2508 tp->snd_wl1 = th->th_seq; 2509 tp->snd_wl2 = th->th_ack; 2510 if (tp->snd_wnd > tp->max_sndwnd) 2511 tp->max_sndwnd = tp->snd_wnd; 2512 needoutput = 1; 2513 } 2514 2515 /* 2516 * Process segments with URG. 2517 */ 2518 if ((tiflags & TH_URG) && th->th_urp && 2519 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2520 /* 2521 * This is a kludge, but if we receive and accept 2522 * random urgent pointers, we'll crash in 2523 * soreceive. It's hard to imagine someone 2524 * actually wanting to send this much urgent data. 2525 */ 2526 if (th->th_urp + so->so_rcv.sb_cc > sb_max) { 2527 th->th_urp = 0; /* XXX */ 2528 tiflags &= ~TH_URG; /* XXX */ 2529 goto dodata; /* XXX */ 2530 } 2531 /* 2532 * If this segment advances the known urgent pointer, 2533 * then mark the data stream. This should not happen 2534 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 2535 * a FIN has been received from the remote side. 2536 * In these states we ignore the URG. 2537 * 2538 * According to RFC961 (Assigned Protocols), 2539 * the urgent pointer points to the last octet 2540 * of urgent data. We continue, however, 2541 * to consider it to indicate the first octet 2542 * of data past the urgent section as the original 2543 * spec states (in one of two places). 2544 */ 2545 if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) { 2546 tp->rcv_up = th->th_seq + th->th_urp; 2547 so->so_oobmark = so->so_rcv.sb_cc + 2548 (tp->rcv_up - tp->rcv_nxt) - 1; 2549 if (so->so_oobmark == 0) 2550 so->so_state |= SS_RCVATMARK; 2551 sohasoutofband(so); 2552 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); 2553 } 2554 /* 2555 * Remove out of band data so doesn't get presented to user. 2556 * This can happen independent of advancing the URG pointer, 2557 * but if two URG's are pending at once, some out-of-band 2558 * data may creep in... ick. 2559 */ 2560 if (th->th_urp <= (u_int16_t) tlen 2561 #ifdef SO_OOBINLINE 2562 && (so->so_options & SO_OOBINLINE) == 0 2563 #endif 2564 ) 2565 tcp_pulloutofband(so, th, m, hdroptlen); 2566 } else 2567 /* 2568 * If no out of band data is expected, 2569 * pull receive urgent pointer along 2570 * with the receive window. 2571 */ 2572 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) 2573 tp->rcv_up = tp->rcv_nxt; 2574 dodata: /* XXX */ 2575 2576 /* 2577 * Process the segment text, merging it into the TCP sequencing queue, 2578 * and arranging for acknowledgement of receipt if necessary. 2579 * This process logically involves adjusting tp->rcv_wnd as data 2580 * is presented to the user (this happens in tcp_usrreq.c, 2581 * case PRU_RCVD). If a FIN has already been received on this 2582 * connection then we just ignore the text. 2583 */ 2584 if ((tlen || (tiflags & TH_FIN)) && 2585 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2586 /* 2587 * Insert segment ti into reassembly queue of tcp with 2588 * control block tp. Return TH_FIN if reassembly now includes 2589 * a segment with FIN. The macro form does the common case 2590 * inline (segment is the next to be received on an 2591 * established connection, and the queue is empty), 2592 * avoiding linkage into and removal from the queue and 2593 * repetition of various conversions. 2594 * Set DELACK for segments received in order, but ack 2595 * immediately when segments are out of order 2596 * (so fast retransmit can work). 2597 */ 2598 /* NOTE: this was TCP_REASS() macro, but used only once */ 2599 TCP_REASS_LOCK(tp); 2600 if (th->th_seq == tp->rcv_nxt && 2601 TAILQ_FIRST(&tp->segq) == NULL && 2602 tp->t_state == TCPS_ESTABLISHED) { 2603 TCP_SETUP_ACK(tp, th); 2604 tp->rcv_nxt += tlen; 2605 tiflags = th->th_flags & TH_FIN; 2606 tcpstat.tcps_rcvpack++; 2607 tcpstat.tcps_rcvbyte += tlen; 2608 nd6_hint(tp); 2609 if (so->so_state & SS_CANTRCVMORE) 2610 m_freem(m); 2611 else { 2612 m_adj(m, hdroptlen); 2613 sbappendstream(&(so)->so_rcv, m); 2614 } 2615 sorwakeup(so); 2616 } else { 2617 m_adj(m, hdroptlen); 2618 tiflags = tcp_reass(tp, th, m, &tlen); 2619 tp->t_flags |= TF_ACKNOW; 2620 } 2621 TCP_REASS_UNLOCK(tp); 2622 2623 /* 2624 * Note the amount of data that peer has sent into 2625 * our window, in order to estimate the sender's 2626 * buffer size. 2627 */ 2628 len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); 2629 } else { 2630 m_freem(m); 2631 m = NULL; 2632 tiflags &= ~TH_FIN; 2633 } 2634 2635 /* 2636 * If FIN is received ACK the FIN and let the user know 2637 * that the connection is closing. Ignore a FIN received before 2638 * the connection is fully established. 2639 */ 2640 if ((tiflags & TH_FIN) && TCPS_HAVEESTABLISHED(tp->t_state)) { 2641 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2642 socantrcvmore(so); 2643 tp->t_flags |= TF_ACKNOW; 2644 tp->rcv_nxt++; 2645 } 2646 switch (tp->t_state) { 2647 2648 /* 2649 * In ESTABLISHED STATE enter the CLOSE_WAIT state. 2650 */ 2651 case TCPS_ESTABLISHED: 2652 tp->t_state = TCPS_CLOSE_WAIT; 2653 break; 2654 2655 /* 2656 * If still in FIN_WAIT_1 STATE FIN has not been acked so 2657 * enter the CLOSING state. 2658 */ 2659 case TCPS_FIN_WAIT_1: 2660 tp->t_state = TCPS_CLOSING; 2661 break; 2662 2663 /* 2664 * In FIN_WAIT_2 state enter the TIME_WAIT state, 2665 * starting the time-wait timer, turning off the other 2666 * standard timers. 2667 */ 2668 case TCPS_FIN_WAIT_2: 2669 tp->t_state = TCPS_TIME_WAIT; 2670 tcp_canceltimers(tp); 2671 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 2672 soisdisconnected(so); 2673 break; 2674 2675 /* 2676 * In TIME_WAIT state restart the 2 MSL time_wait timer. 2677 */ 2678 case TCPS_TIME_WAIT: 2679 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 2680 break; 2681 } 2682 } 2683 #ifdef TCP_DEBUG 2684 if (so->so_options & SO_DEBUG) 2685 tcp_trace(TA_INPUT, ostate, tp, tcp_saveti, 0); 2686 #endif 2687 2688 /* 2689 * Return any desired output. 2690 */ 2691 if (needoutput || (tp->t_flags & TF_ACKNOW)) { 2692 (void) tcp_output(tp); 2693 } 2694 if (tcp_saveti) 2695 m_freem(tcp_saveti); 2696 return; 2697 2698 badsyn: 2699 /* 2700 * Received a bad SYN. Increment counters and dropwithreset. 2701 */ 2702 tcpstat.tcps_badsyn++; 2703 tp = NULL; 2704 goto dropwithreset; 2705 2706 dropafterack: 2707 /* 2708 * Generate an ACK dropping incoming segment if it occupies 2709 * sequence space, where the ACK reflects our state. 2710 */ 2711 if (tiflags & TH_RST) 2712 goto drop; 2713 goto dropafterack2; 2714 2715 dropafterack_ratelim: 2716 /* 2717 * We may want to rate-limit ACKs against SYN/RST attack. 2718 */ 2719 if (ppsratecheck(&tcp_ackdrop_ppslim_last, &tcp_ackdrop_ppslim_count, 2720 tcp_ackdrop_ppslim) == 0) { 2721 /* XXX stat */ 2722 goto drop; 2723 } 2724 /* ...fall into dropafterack2... */ 2725 2726 dropafterack2: 2727 m_freem(m); 2728 tp->t_flags |= TF_ACKNOW; 2729 (void) tcp_output(tp); 2730 if (tcp_saveti) 2731 m_freem(tcp_saveti); 2732 return; 2733 2734 dropwithreset_ratelim: 2735 /* 2736 * We may want to rate-limit RSTs in certain situations, 2737 * particularly if we are sending an RST in response to 2738 * an attempt to connect to or otherwise communicate with 2739 * a port for which we have no socket. 2740 */ 2741 if (ppsratecheck(&tcp_rst_ppslim_last, &tcp_rst_ppslim_count, 2742 tcp_rst_ppslim) == 0) { 2743 /* XXX stat */ 2744 goto drop; 2745 } 2746 /* ...fall into dropwithreset... */ 2747 2748 dropwithreset: 2749 /* 2750 * Generate a RST, dropping incoming segment. 2751 * Make ACK acceptable to originator of segment. 2752 */ 2753 if (tiflags & TH_RST) 2754 goto drop; 2755 2756 switch (af) { 2757 #ifdef INET6 2758 case AF_INET6: 2759 /* For following calls to tcp_respond */ 2760 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) 2761 goto drop; 2762 break; 2763 #endif /* INET6 */ 2764 case AF_INET: 2765 if (IN_MULTICAST(ip->ip_dst.s_addr) || 2766 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 2767 goto drop; 2768 } 2769 2770 if (tiflags & TH_ACK) 2771 (void)tcp_respond(tp, m, m, th, (tcp_seq)0, th->th_ack, TH_RST); 2772 else { 2773 if (tiflags & TH_SYN) 2774 tlen++; 2775 (void)tcp_respond(tp, m, m, th, th->th_seq + tlen, (tcp_seq)0, 2776 TH_RST|TH_ACK); 2777 } 2778 if (tcp_saveti) 2779 m_freem(tcp_saveti); 2780 return; 2781 2782 badcsum: 2783 drop: 2784 /* 2785 * Drop space held by incoming segment and return. 2786 */ 2787 if (tp) { 2788 if (tp->t_inpcb) 2789 so = tp->t_inpcb->inp_socket; 2790 #ifdef INET6 2791 else if (tp->t_in6pcb) 2792 so = tp->t_in6pcb->in6p_socket; 2793 #endif 2794 else 2795 so = NULL; 2796 #ifdef TCP_DEBUG 2797 if (so && (so->so_options & SO_DEBUG) != 0) 2798 tcp_trace(TA_DROP, ostate, tp, tcp_saveti, 0); 2799 #endif 2800 } 2801 if (tcp_saveti) 2802 m_freem(tcp_saveti); 2803 m_freem(m); 2804 return; 2805 } 2806 2807 #ifdef TCP_SIGNATURE 2808 int 2809 tcp_signature_apply(void *fstate, void *data, u_int len) 2810 { 2811 2812 MD5Update(fstate, (u_char *)data, len); 2813 return (0); 2814 } 2815 2816 struct secasvar * 2817 tcp_signature_getsav(struct mbuf *m, struct tcphdr *th) 2818 { 2819 struct secasvar *sav; 2820 #ifdef FAST_IPSEC 2821 union sockaddr_union dst; 2822 #endif 2823 struct ip *ip; 2824 struct ip6_hdr *ip6; 2825 2826 ip = mtod(m, struct ip *); 2827 switch (ip->ip_v) { 2828 case 4: 2829 ip = mtod(m, struct ip *); 2830 ip6 = NULL; 2831 break; 2832 case 6: 2833 ip = NULL; 2834 ip6 = mtod(m, struct ip6_hdr *); 2835 break; 2836 default: 2837 return (NULL); 2838 } 2839 2840 #ifdef FAST_IPSEC 2841 /* Extract the destination from the IP header in the mbuf. */ 2842 bzero(&dst, sizeof(union sockaddr_union)); 2843 if (ip !=NULL) { 2844 dst.sa.sa_len = sizeof(struct sockaddr_in); 2845 dst.sa.sa_family = AF_INET; 2846 dst.sin.sin_addr = ip->ip_dst; 2847 } else { 2848 dst.sa.sa_len = sizeof(struct sockaddr_in6); 2849 dst.sa.sa_family = AF_INET6; 2850 dst.sin6.sin6_addr = ip6->ip6_dst; 2851 } 2852 2853 /* 2854 * Look up an SADB entry which matches the address of the peer. 2855 */ 2856 sav = KEY_ALLOCSA(&dst, IPPROTO_TCP, htonl(TCP_SIG_SPI)); 2857 #else 2858 if (ip) 2859 sav = key_allocsa(AF_INET, (void *)&ip->ip_src, 2860 (void *)&ip->ip_dst, IPPROTO_TCP, 2861 htonl(TCP_SIG_SPI), 0, 0); 2862 else 2863 sav = key_allocsa(AF_INET6, (void *)&ip6->ip6_src, 2864 (void *)&ip6->ip6_dst, IPPROTO_TCP, 2865 htonl(TCP_SIG_SPI), 0, 0); 2866 #endif 2867 2868 return (sav); /* freesav must be performed by caller */ 2869 } 2870 2871 int 2872 tcp_signature(struct mbuf *m, struct tcphdr *th, int thoff, 2873 struct secasvar *sav, char *sig) 2874 { 2875 MD5_CTX ctx; 2876 struct ip *ip; 2877 struct ipovly *ipovly; 2878 struct ip6_hdr *ip6; 2879 struct ippseudo ippseudo; 2880 struct ip6_hdr_pseudo ip6pseudo; 2881 struct tcphdr th0; 2882 int l, tcphdrlen; 2883 2884 if (sav == NULL) 2885 return (-1); 2886 2887 tcphdrlen = th->th_off * 4; 2888 2889 switch (mtod(m, struct ip *)->ip_v) { 2890 case 4: 2891 ip = mtod(m, struct ip *); 2892 ip6 = NULL; 2893 break; 2894 case 6: 2895 ip = NULL; 2896 ip6 = mtod(m, struct ip6_hdr *); 2897 break; 2898 default: 2899 return (-1); 2900 } 2901 2902 MD5Init(&ctx); 2903 2904 if (ip) { 2905 memset(&ippseudo, 0, sizeof(ippseudo)); 2906 ipovly = (struct ipovly *)ip; 2907 ippseudo.ippseudo_src = ipovly->ih_src; 2908 ippseudo.ippseudo_dst = ipovly->ih_dst; 2909 ippseudo.ippseudo_pad = 0; 2910 ippseudo.ippseudo_p = IPPROTO_TCP; 2911 ippseudo.ippseudo_len = htons(m->m_pkthdr.len - thoff); 2912 MD5Update(&ctx, (char *)&ippseudo, sizeof(ippseudo)); 2913 } else { 2914 memset(&ip6pseudo, 0, sizeof(ip6pseudo)); 2915 ip6pseudo.ip6ph_src = ip6->ip6_src; 2916 in6_clearscope(&ip6pseudo.ip6ph_src); 2917 ip6pseudo.ip6ph_dst = ip6->ip6_dst; 2918 in6_clearscope(&ip6pseudo.ip6ph_dst); 2919 ip6pseudo.ip6ph_len = htons(m->m_pkthdr.len - thoff); 2920 ip6pseudo.ip6ph_nxt = IPPROTO_TCP; 2921 MD5Update(&ctx, (char *)&ip6pseudo, sizeof(ip6pseudo)); 2922 } 2923 2924 th0 = *th; 2925 th0.th_sum = 0; 2926 MD5Update(&ctx, (char *)&th0, sizeof(th0)); 2927 2928 l = m->m_pkthdr.len - thoff - tcphdrlen; 2929 if (l > 0) 2930 m_apply(m, thoff + tcphdrlen, 2931 m->m_pkthdr.len - thoff - tcphdrlen, 2932 tcp_signature_apply, &ctx); 2933 2934 MD5Update(&ctx, _KEYBUF(sav->key_auth), _KEYLEN(sav->key_auth)); 2935 MD5Final(sig, &ctx); 2936 2937 return (0); 2938 } 2939 #endif 2940 2941 static int 2942 tcp_dooptions(struct tcpcb *tp, const u_char *cp, int cnt, 2943 struct tcphdr *th, 2944 struct mbuf *m, int toff, struct tcp_opt_info *oi) 2945 { 2946 u_int16_t mss; 2947 int opt, optlen = 0; 2948 #ifdef TCP_SIGNATURE 2949 void *sigp = NULL; 2950 char sigbuf[TCP_SIGLEN]; 2951 struct secasvar *sav = NULL; 2952 #endif 2953 2954 for (; cp && cnt > 0; cnt -= optlen, cp += optlen) { 2955 opt = cp[0]; 2956 if (opt == TCPOPT_EOL) 2957 break; 2958 if (opt == TCPOPT_NOP) 2959 optlen = 1; 2960 else { 2961 if (cnt < 2) 2962 break; 2963 optlen = cp[1]; 2964 if (optlen < 2 || optlen > cnt) 2965 break; 2966 } 2967 switch (opt) { 2968 2969 default: 2970 continue; 2971 2972 case TCPOPT_MAXSEG: 2973 if (optlen != TCPOLEN_MAXSEG) 2974 continue; 2975 if (!(th->th_flags & TH_SYN)) 2976 continue; 2977 if (TCPS_HAVERCVDSYN(tp->t_state)) 2978 continue; 2979 bcopy(cp + 2, &mss, sizeof(mss)); 2980 oi->maxseg = ntohs(mss); 2981 break; 2982 2983 case TCPOPT_WINDOW: 2984 if (optlen != TCPOLEN_WINDOW) 2985 continue; 2986 if (!(th->th_flags & TH_SYN)) 2987 continue; 2988 if (TCPS_HAVERCVDSYN(tp->t_state)) 2989 continue; 2990 tp->t_flags |= TF_RCVD_SCALE; 2991 tp->requested_s_scale = cp[2]; 2992 if (tp->requested_s_scale > TCP_MAX_WINSHIFT) { 2993 #if 0 /*XXX*/ 2994 char *p; 2995 2996 if (ip) 2997 p = ntohl(ip->ip_src); 2998 #ifdef INET6 2999 else if (ip6) 3000 p = ip6_sprintf(&ip6->ip6_src); 3001 #endif 3002 else 3003 p = "(unknown)"; 3004 log(LOG_ERR, "TCP: invalid wscale %d from %s, " 3005 "assuming %d\n", 3006 tp->requested_s_scale, p, 3007 TCP_MAX_WINSHIFT); 3008 #else 3009 log(LOG_ERR, "TCP: invalid wscale %d, " 3010 "assuming %d\n", 3011 tp->requested_s_scale, 3012 TCP_MAX_WINSHIFT); 3013 #endif 3014 tp->requested_s_scale = TCP_MAX_WINSHIFT; 3015 } 3016 break; 3017 3018 case TCPOPT_TIMESTAMP: 3019 if (optlen != TCPOLEN_TIMESTAMP) 3020 continue; 3021 oi->ts_present = 1; 3022 bcopy(cp + 2, &oi->ts_val, sizeof(oi->ts_val)); 3023 NTOHL(oi->ts_val); 3024 bcopy(cp + 6, &oi->ts_ecr, sizeof(oi->ts_ecr)); 3025 NTOHL(oi->ts_ecr); 3026 3027 if (!(th->th_flags & TH_SYN)) 3028 continue; 3029 if (TCPS_HAVERCVDSYN(tp->t_state)) 3030 continue; 3031 /* 3032 * A timestamp received in a SYN makes 3033 * it ok to send timestamp requests and replies. 3034 */ 3035 tp->t_flags |= TF_RCVD_TSTMP; 3036 tp->ts_recent = oi->ts_val; 3037 tp->ts_recent_age = tcp_now; 3038 break; 3039 3040 case TCPOPT_SACK_PERMITTED: 3041 if (optlen != TCPOLEN_SACK_PERMITTED) 3042 continue; 3043 if (!(th->th_flags & TH_SYN)) 3044 continue; 3045 if (TCPS_HAVERCVDSYN(tp->t_state)) 3046 continue; 3047 if (tcp_do_sack) { 3048 tp->t_flags |= TF_SACK_PERMIT; 3049 tp->t_flags |= TF_WILL_SACK; 3050 } 3051 break; 3052 3053 case TCPOPT_SACK: 3054 tcp_sack_option(tp, th, cp, optlen); 3055 break; 3056 #ifdef TCP_SIGNATURE 3057 case TCPOPT_SIGNATURE: 3058 if (optlen != TCPOLEN_SIGNATURE) 3059 continue; 3060 if (sigp && bcmp(sigp, cp + 2, TCP_SIGLEN)) 3061 return (-1); 3062 3063 sigp = sigbuf; 3064 memcpy(sigbuf, cp + 2, TCP_SIGLEN); 3065 tp->t_flags |= TF_SIGNATURE; 3066 break; 3067 #endif 3068 } 3069 } 3070 3071 #ifdef TCP_SIGNATURE 3072 if (tp->t_flags & TF_SIGNATURE) { 3073 3074 sav = tcp_signature_getsav(m, th); 3075 3076 if (sav == NULL && tp->t_state == TCPS_LISTEN) 3077 return (-1); 3078 } 3079 3080 if ((sigp ? TF_SIGNATURE : 0) ^ (tp->t_flags & TF_SIGNATURE)) { 3081 if (sav == NULL) 3082 return (-1); 3083 #ifdef FAST_IPSEC 3084 KEY_FREESAV(&sav); 3085 #else 3086 key_freesav(sav); 3087 #endif 3088 return (-1); 3089 } 3090 3091 if (sigp) { 3092 char sig[TCP_SIGLEN]; 3093 3094 TCP_FIELDS_TO_NET(th); 3095 if (tcp_signature(m, th, toff, sav, sig) < 0) { 3096 TCP_FIELDS_TO_HOST(th); 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 } 3106 TCP_FIELDS_TO_HOST(th); 3107 3108 if (bcmp(sig, sigp, TCP_SIGLEN)) { 3109 tcpstat.tcps_badsig++; 3110 if (sav == NULL) 3111 return (-1); 3112 #ifdef FAST_IPSEC 3113 KEY_FREESAV(&sav); 3114 #else 3115 key_freesav(sav); 3116 #endif 3117 return (-1); 3118 } else 3119 tcpstat.tcps_goodsig++; 3120 3121 key_sa_recordxfer(sav, m); 3122 #ifdef FAST_IPSEC 3123 KEY_FREESAV(&sav); 3124 #else 3125 key_freesav(sav); 3126 #endif 3127 } 3128 #endif 3129 3130 return (0); 3131 } 3132 3133 /* 3134 * Pull out of band byte out of a segment so 3135 * it doesn't appear in the user's data queue. 3136 * It is still reflected in the segment length for 3137 * sequencing purposes. 3138 */ 3139 void 3140 tcp_pulloutofband(struct socket *so, struct tcphdr *th, 3141 struct mbuf *m, int off) 3142 { 3143 int cnt = off + th->th_urp - 1; 3144 3145 while (cnt >= 0) { 3146 if (m->m_len > cnt) { 3147 char *cp = mtod(m, char *) + cnt; 3148 struct tcpcb *tp = sototcpcb(so); 3149 3150 tp->t_iobc = *cp; 3151 tp->t_oobflags |= TCPOOB_HAVEDATA; 3152 bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); 3153 m->m_len--; 3154 return; 3155 } 3156 cnt -= m->m_len; 3157 m = m->m_next; 3158 if (m == 0) 3159 break; 3160 } 3161 panic("tcp_pulloutofband"); 3162 } 3163 3164 /* 3165 * Collect new round-trip time estimate 3166 * and update averages and current timeout. 3167 */ 3168 void 3169 tcp_xmit_timer(struct tcpcb *tp, uint32_t rtt) 3170 { 3171 int32_t delta; 3172 3173 tcpstat.tcps_rttupdated++; 3174 if (tp->t_srtt != 0) { 3175 /* 3176 * srtt is stored as fixed point with 3 bits after the 3177 * binary point (i.e., scaled by 8). The following magic 3178 * is equivalent to the smoothing algorithm in rfc793 with 3179 * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed 3180 * point). Adjust rtt to origin 0. 3181 */ 3182 delta = (rtt << 2) - (tp->t_srtt >> TCP_RTT_SHIFT); 3183 if ((tp->t_srtt += delta) <= 0) 3184 tp->t_srtt = 1 << 2; 3185 /* 3186 * We accumulate a smoothed rtt variance (actually, a 3187 * smoothed mean difference), then set the retransmit 3188 * timer to smoothed rtt + 4 times the smoothed variance. 3189 * rttvar is stored as fixed point with 2 bits after the 3190 * binary point (scaled by 4). The following is 3191 * equivalent to rfc793 smoothing with an alpha of .75 3192 * (rttvar = rttvar*3/4 + |delta| / 4). This replaces 3193 * rfc793's wired-in beta. 3194 */ 3195 if (delta < 0) 3196 delta = -delta; 3197 delta -= (tp->t_rttvar >> TCP_RTTVAR_SHIFT); 3198 if ((tp->t_rttvar += delta) <= 0) 3199 tp->t_rttvar = 1 << 2; 3200 } else { 3201 /* 3202 * No rtt measurement yet - use the unsmoothed rtt. 3203 * Set the variance to half the rtt (so our first 3204 * retransmit happens at 3*rtt). 3205 */ 3206 tp->t_srtt = rtt << (TCP_RTT_SHIFT + 2); 3207 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT + 2 - 1); 3208 } 3209 tp->t_rtttime = 0; 3210 tp->t_rxtshift = 0; 3211 3212 /* 3213 * the retransmit should happen at rtt + 4 * rttvar. 3214 * Because of the way we do the smoothing, srtt and rttvar 3215 * will each average +1/2 tick of bias. When we compute 3216 * the retransmit timer, we want 1/2 tick of rounding and 3217 * 1 extra tick because of +-1/2 tick uncertainty in the 3218 * firing of the timer. The bias will give us exactly the 3219 * 1.5 tick we need. But, because the bias is 3220 * statistical, we have to test that we don't drop below 3221 * the minimum feasible timer (which is 2 ticks). 3222 */ 3223 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), 3224 max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX); 3225 3226 /* 3227 * We received an ack for a packet that wasn't retransmitted; 3228 * it is probably safe to discard any error indications we've 3229 * received recently. This isn't quite right, but close enough 3230 * for now (a route might have failed after we sent a segment, 3231 * and the return path might not be symmetrical). 3232 */ 3233 tp->t_softerror = 0; 3234 } 3235 3236 3237 /* 3238 * TCP compressed state engine. Currently used to hold compressed 3239 * state for SYN_RECEIVED. 3240 */ 3241 3242 u_long syn_cache_count; 3243 u_int32_t syn_hash1, syn_hash2; 3244 3245 #define SYN_HASH(sa, sp, dp) \ 3246 ((((sa)->s_addr^syn_hash1)*(((((u_int32_t)(dp))<<16) + \ 3247 ((u_int32_t)(sp)))^syn_hash2))) 3248 #ifndef INET6 3249 #define SYN_HASHALL(hash, src, dst) \ 3250 do { \ 3251 hash = SYN_HASH(&((const struct sockaddr_in *)(src))->sin_addr, \ 3252 ((const struct sockaddr_in *)(src))->sin_port, \ 3253 ((const struct sockaddr_in *)(dst))->sin_port); \ 3254 } while (/*CONSTCOND*/ 0) 3255 #else 3256 #define SYN_HASH6(sa, sp, dp) \ 3257 ((((sa)->s6_addr32[0] ^ (sa)->s6_addr32[3] ^ syn_hash1) * \ 3258 (((((u_int32_t)(dp))<<16) + ((u_int32_t)(sp)))^syn_hash2)) \ 3259 & 0x7fffffff) 3260 3261 #define SYN_HASHALL(hash, src, dst) \ 3262 do { \ 3263 switch ((src)->sa_family) { \ 3264 case AF_INET: \ 3265 hash = SYN_HASH(&((const struct sockaddr_in *)(src))->sin_addr, \ 3266 ((const struct sockaddr_in *)(src))->sin_port, \ 3267 ((const struct sockaddr_in *)(dst))->sin_port); \ 3268 break; \ 3269 case AF_INET6: \ 3270 hash = SYN_HASH6(&((const struct sockaddr_in6 *)(src))->sin6_addr, \ 3271 ((const struct sockaddr_in6 *)(src))->sin6_port, \ 3272 ((const struct sockaddr_in6 *)(dst))->sin6_port); \ 3273 break; \ 3274 default: \ 3275 hash = 0; \ 3276 } \ 3277 } while (/*CONSTCOND*/0) 3278 #endif /* INET6 */ 3279 3280 POOL_INIT(syn_cache_pool, sizeof(struct syn_cache), 0, 0, 0, "synpl", NULL, 3281 IPL_SOFTNET); 3282 3283 /* 3284 * We don't estimate RTT with SYNs, so each packet starts with the default 3285 * RTT and each timer step has a fixed timeout value. 3286 */ 3287 #define SYN_CACHE_TIMER_ARM(sc) \ 3288 do { \ 3289 TCPT_RANGESET((sc)->sc_rxtcur, \ 3290 TCPTV_SRTTDFLT * tcp_backoff[(sc)->sc_rxtshift], TCPTV_MIN, \ 3291 TCPTV_REXMTMAX); \ 3292 callout_reset(&(sc)->sc_timer, \ 3293 (sc)->sc_rxtcur * (hz / PR_SLOWHZ), syn_cache_timer, (sc)); \ 3294 } while (/*CONSTCOND*/0) 3295 3296 #define SYN_CACHE_TIMESTAMP(sc) (tcp_now - (sc)->sc_timebase) 3297 3298 static inline void 3299 syn_cache_rm(struct syn_cache *sc) 3300 { 3301 TAILQ_REMOVE(&tcp_syn_cache[sc->sc_bucketidx].sch_bucket, 3302 sc, sc_bucketq); 3303 sc->sc_tp = NULL; 3304 LIST_REMOVE(sc, sc_tpq); 3305 tcp_syn_cache[sc->sc_bucketidx].sch_length--; 3306 callout_stop(&sc->sc_timer); 3307 syn_cache_count--; 3308 } 3309 3310 static inline void 3311 syn_cache_put(struct syn_cache *sc) 3312 { 3313 if (sc->sc_ipopts) 3314 (void) m_free(sc->sc_ipopts); 3315 rtcache_free(&sc->sc_route); 3316 if (callout_invoking(&sc->sc_timer)) 3317 sc->sc_flags |= SCF_DEAD; 3318 else { 3319 callout_destroy(&sc->sc_timer); 3320 pool_put(&syn_cache_pool, sc); 3321 } 3322 } 3323 3324 void 3325 syn_cache_init(void) 3326 { 3327 int i; 3328 3329 /* Initialize the hash buckets. */ 3330 for (i = 0; i < tcp_syn_cache_size; i++) 3331 TAILQ_INIT(&tcp_syn_cache[i].sch_bucket); 3332 } 3333 3334 void 3335 syn_cache_insert(struct syn_cache *sc, struct tcpcb *tp) 3336 { 3337 struct syn_cache_head *scp; 3338 struct syn_cache *sc2; 3339 int s; 3340 3341 /* 3342 * If there are no entries in the hash table, reinitialize 3343 * the hash secrets. 3344 */ 3345 if (syn_cache_count == 0) { 3346 syn_hash1 = arc4random(); 3347 syn_hash2 = arc4random(); 3348 } 3349 3350 SYN_HASHALL(sc->sc_hash, &sc->sc_src.sa, &sc->sc_dst.sa); 3351 sc->sc_bucketidx = sc->sc_hash % tcp_syn_cache_size; 3352 scp = &tcp_syn_cache[sc->sc_bucketidx]; 3353 3354 /* 3355 * Make sure that we don't overflow the per-bucket 3356 * limit or the total cache size limit. 3357 */ 3358 s = splsoftnet(); 3359 if (scp->sch_length >= tcp_syn_bucket_limit) { 3360 tcpstat.tcps_sc_bucketoverflow++; 3361 /* 3362 * The bucket is full. Toss the oldest element in the 3363 * bucket. This will be the first entry in the bucket. 3364 */ 3365 sc2 = TAILQ_FIRST(&scp->sch_bucket); 3366 #ifdef DIAGNOSTIC 3367 /* 3368 * This should never happen; we should always find an 3369 * entry in our bucket. 3370 */ 3371 if (sc2 == NULL) 3372 panic("syn_cache_insert: bucketoverflow: impossible"); 3373 #endif 3374 syn_cache_rm(sc2); 3375 syn_cache_put(sc2); /* calls pool_put but see spl above */ 3376 } else if (syn_cache_count >= tcp_syn_cache_limit) { 3377 struct syn_cache_head *scp2, *sce; 3378 3379 tcpstat.tcps_sc_overflowed++; 3380 /* 3381 * The cache is full. Toss the oldest entry in the 3382 * first non-empty bucket we can find. 3383 * 3384 * XXX We would really like to toss the oldest 3385 * entry in the cache, but we hope that this 3386 * condition doesn't happen very often. 3387 */ 3388 scp2 = scp; 3389 if (TAILQ_EMPTY(&scp2->sch_bucket)) { 3390 sce = &tcp_syn_cache[tcp_syn_cache_size]; 3391 for (++scp2; scp2 != scp; scp2++) { 3392 if (scp2 >= sce) 3393 scp2 = &tcp_syn_cache[0]; 3394 if (! TAILQ_EMPTY(&scp2->sch_bucket)) 3395 break; 3396 } 3397 #ifdef DIAGNOSTIC 3398 /* 3399 * This should never happen; we should always find a 3400 * non-empty bucket. 3401 */ 3402 if (scp2 == scp) 3403 panic("syn_cache_insert: cacheoverflow: " 3404 "impossible"); 3405 #endif 3406 } 3407 sc2 = TAILQ_FIRST(&scp2->sch_bucket); 3408 syn_cache_rm(sc2); 3409 syn_cache_put(sc2); /* calls pool_put but see spl above */ 3410 } 3411 3412 /* 3413 * Initialize the entry's timer. 3414 */ 3415 sc->sc_rxttot = 0; 3416 sc->sc_rxtshift = 0; 3417 SYN_CACHE_TIMER_ARM(sc); 3418 3419 /* Link it from tcpcb entry */ 3420 LIST_INSERT_HEAD(&tp->t_sc, sc, sc_tpq); 3421 3422 /* Put it into the bucket. */ 3423 TAILQ_INSERT_TAIL(&scp->sch_bucket, sc, sc_bucketq); 3424 scp->sch_length++; 3425 syn_cache_count++; 3426 3427 tcpstat.tcps_sc_added++; 3428 splx(s); 3429 } 3430 3431 /* 3432 * Walk the timer queues, looking for SYN,ACKs that need to be retransmitted. 3433 * If we have retransmitted an entry the maximum number of times, expire 3434 * that entry. 3435 */ 3436 void 3437 syn_cache_timer(void *arg) 3438 { 3439 struct syn_cache *sc = arg; 3440 int s; 3441 3442 s = splsoftnet(); 3443 callout_ack(&sc->sc_timer); 3444 3445 if (__predict_false(sc->sc_flags & SCF_DEAD)) { 3446 tcpstat.tcps_sc_delayed_free++; 3447 callout_destroy(&sc->sc_timer); 3448 pool_put(&syn_cache_pool, sc); 3449 splx(s); 3450 return; 3451 } 3452 3453 if (__predict_false(sc->sc_rxtshift == TCP_MAXRXTSHIFT)) { 3454 /* Drop it -- too many retransmissions. */ 3455 goto dropit; 3456 } 3457 3458 /* 3459 * Compute the total amount of time this entry has 3460 * been on a queue. If this entry has been on longer 3461 * than the keep alive timer would allow, expire it. 3462 */ 3463 sc->sc_rxttot += sc->sc_rxtcur; 3464 if (sc->sc_rxttot >= tcp_keepinit) 3465 goto dropit; 3466 3467 tcpstat.tcps_sc_retransmitted++; 3468 (void) syn_cache_respond(sc, NULL); 3469 3470 /* Advance the timer back-off. */ 3471 sc->sc_rxtshift++; 3472 SYN_CACHE_TIMER_ARM(sc); 3473 3474 splx(s); 3475 return; 3476 3477 dropit: 3478 tcpstat.tcps_sc_timed_out++; 3479 syn_cache_rm(sc); 3480 syn_cache_put(sc); /* calls pool_put but see spl above */ 3481 splx(s); 3482 } 3483 3484 /* 3485 * Remove syn cache created by the specified tcb entry, 3486 * because this does not make sense to keep them 3487 * (if there's no tcb entry, syn cache entry will never be used) 3488 */ 3489 void 3490 syn_cache_cleanup(struct tcpcb *tp) 3491 { 3492 struct syn_cache *sc, *nsc; 3493 int s; 3494 3495 s = splsoftnet(); 3496 3497 for (sc = LIST_FIRST(&tp->t_sc); sc != NULL; sc = nsc) { 3498 nsc = LIST_NEXT(sc, sc_tpq); 3499 3500 #ifdef DIAGNOSTIC 3501 if (sc->sc_tp != tp) 3502 panic("invalid sc_tp in syn_cache_cleanup"); 3503 #endif 3504 syn_cache_rm(sc); 3505 syn_cache_put(sc); /* calls pool_put but see spl above */ 3506 } 3507 /* just for safety */ 3508 LIST_INIT(&tp->t_sc); 3509 3510 splx(s); 3511 } 3512 3513 /* 3514 * Find an entry in the syn cache. 3515 */ 3516 struct syn_cache * 3517 syn_cache_lookup(const struct sockaddr *src, const struct sockaddr *dst, 3518 struct syn_cache_head **headp) 3519 { 3520 struct syn_cache *sc; 3521 struct syn_cache_head *scp; 3522 u_int32_t hash; 3523 int s; 3524 3525 SYN_HASHALL(hash, src, dst); 3526 3527 scp = &tcp_syn_cache[hash % tcp_syn_cache_size]; 3528 *headp = scp; 3529 s = splsoftnet(); 3530 for (sc = TAILQ_FIRST(&scp->sch_bucket); sc != NULL; 3531 sc = TAILQ_NEXT(sc, sc_bucketq)) { 3532 if (sc->sc_hash != hash) 3533 continue; 3534 if (!bcmp(&sc->sc_src, src, src->sa_len) && 3535 !bcmp(&sc->sc_dst, dst, dst->sa_len)) { 3536 splx(s); 3537 return (sc); 3538 } 3539 } 3540 splx(s); 3541 return (NULL); 3542 } 3543 3544 /* 3545 * This function gets called when we receive an ACK for a 3546 * socket in the LISTEN state. We look up the connection 3547 * in the syn cache, and if its there, we pull it out of 3548 * the cache and turn it into a full-blown connection in 3549 * the SYN-RECEIVED state. 3550 * 3551 * The return values may not be immediately obvious, and their effects 3552 * can be subtle, so here they are: 3553 * 3554 * NULL SYN was not found in cache; caller should drop the 3555 * packet and send an RST. 3556 * 3557 * -1 We were unable to create the new connection, and are 3558 * aborting it. An ACK,RST is being sent to the peer 3559 * (unless we got screwey sequence numbners; see below), 3560 * because the 3-way handshake has been completed. Caller 3561 * should not free the mbuf, since we may be using it. If 3562 * we are not, we will free it. 3563 * 3564 * Otherwise, the return value is a pointer to the new socket 3565 * associated with the connection. 3566 */ 3567 struct socket * 3568 syn_cache_get(struct sockaddr *src, struct sockaddr *dst, 3569 struct tcphdr *th, unsigned int hlen, unsigned int tlen, 3570 struct socket *so, struct mbuf *m) 3571 { 3572 struct syn_cache *sc; 3573 struct syn_cache_head *scp; 3574 struct inpcb *inp = NULL; 3575 #ifdef INET6 3576 struct in6pcb *in6p = NULL; 3577 #endif 3578 struct tcpcb *tp = 0; 3579 struct mbuf *am; 3580 int s; 3581 struct socket *oso; 3582 3583 s = splsoftnet(); 3584 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 3585 splx(s); 3586 return (NULL); 3587 } 3588 3589 /* 3590 * Verify the sequence and ack numbers. Try getting the correct 3591 * response again. 3592 */ 3593 if ((th->th_ack != sc->sc_iss + 1) || 3594 SEQ_LEQ(th->th_seq, sc->sc_irs) || 3595 SEQ_GT(th->th_seq, sc->sc_irs + 1 + sc->sc_win)) { 3596 (void) syn_cache_respond(sc, m); 3597 splx(s); 3598 return ((struct socket *)(-1)); 3599 } 3600 3601 /* Remove this cache entry */ 3602 syn_cache_rm(sc); 3603 splx(s); 3604 3605 /* 3606 * Ok, create the full blown connection, and set things up 3607 * as they would have been set up if we had created the 3608 * connection when the SYN arrived. If we can't create 3609 * the connection, abort it. 3610 */ 3611 /* 3612 * inp still has the OLD in_pcb stuff, set the 3613 * v6-related flags on the new guy, too. This is 3614 * done particularly for the case where an AF_INET6 3615 * socket is bound only to a port, and a v4 connection 3616 * comes in on that port. 3617 * we also copy the flowinfo from the original pcb 3618 * to the new one. 3619 */ 3620 oso = so; 3621 so = sonewconn(so, SS_ISCONNECTED); 3622 if (so == NULL) 3623 goto resetandabort; 3624 3625 switch (so->so_proto->pr_domain->dom_family) { 3626 #ifdef INET 3627 case AF_INET: 3628 inp = sotoinpcb(so); 3629 break; 3630 #endif 3631 #ifdef INET6 3632 case AF_INET6: 3633 in6p = sotoin6pcb(so); 3634 break; 3635 #endif 3636 } 3637 switch (src->sa_family) { 3638 #ifdef INET 3639 case AF_INET: 3640 if (inp) { 3641 inp->inp_laddr = ((struct sockaddr_in *)dst)->sin_addr; 3642 inp->inp_lport = ((struct sockaddr_in *)dst)->sin_port; 3643 inp->inp_options = ip_srcroute(); 3644 in_pcbstate(inp, INP_BOUND); 3645 if (inp->inp_options == NULL) { 3646 inp->inp_options = sc->sc_ipopts; 3647 sc->sc_ipopts = NULL; 3648 } 3649 } 3650 #ifdef INET6 3651 else if (in6p) { 3652 /* IPv4 packet to AF_INET6 socket */ 3653 bzero(&in6p->in6p_laddr, sizeof(in6p->in6p_laddr)); 3654 in6p->in6p_laddr.s6_addr16[5] = htons(0xffff); 3655 bcopy(&((struct sockaddr_in *)dst)->sin_addr, 3656 &in6p->in6p_laddr.s6_addr32[3], 3657 sizeof(((struct sockaddr_in *)dst)->sin_addr)); 3658 in6p->in6p_lport = ((struct sockaddr_in *)dst)->sin_port; 3659 in6totcpcb(in6p)->t_family = AF_INET; 3660 if (sotoin6pcb(oso)->in6p_flags & IN6P_IPV6_V6ONLY) 3661 in6p->in6p_flags |= IN6P_IPV6_V6ONLY; 3662 else 3663 in6p->in6p_flags &= ~IN6P_IPV6_V6ONLY; 3664 in6_pcbstate(in6p, IN6P_BOUND); 3665 } 3666 #endif 3667 break; 3668 #endif 3669 #ifdef INET6 3670 case AF_INET6: 3671 if (in6p) { 3672 in6p->in6p_laddr = ((struct sockaddr_in6 *)dst)->sin6_addr; 3673 in6p->in6p_lport = ((struct sockaddr_in6 *)dst)->sin6_port; 3674 in6_pcbstate(in6p, IN6P_BOUND); 3675 } 3676 break; 3677 #endif 3678 } 3679 #ifdef INET6 3680 if (in6p && in6totcpcb(in6p)->t_family == AF_INET6 && sotoinpcb(oso)) { 3681 struct in6pcb *oin6p = sotoin6pcb(oso); 3682 /* inherit socket options from the listening socket */ 3683 in6p->in6p_flags |= (oin6p->in6p_flags & IN6P_CONTROLOPTS); 3684 if (in6p->in6p_flags & IN6P_CONTROLOPTS) { 3685 m_freem(in6p->in6p_options); 3686 in6p->in6p_options = 0; 3687 } 3688 ip6_savecontrol(in6p, &in6p->in6p_options, 3689 mtod(m, struct ip6_hdr *), m); 3690 } 3691 #endif 3692 3693 #if defined(IPSEC) || defined(FAST_IPSEC) 3694 /* 3695 * we make a copy of policy, instead of sharing the policy, 3696 * for better behavior in terms of SA lookup and dead SA removal. 3697 */ 3698 if (inp) { 3699 /* copy old policy into new socket's */ 3700 if (ipsec_copy_pcbpolicy(sotoinpcb(oso)->inp_sp, inp->inp_sp)) 3701 printf("tcp_input: could not copy policy\n"); 3702 } 3703 #ifdef INET6 3704 else if (in6p) { 3705 /* copy old policy into new socket's */ 3706 if (ipsec_copy_pcbpolicy(sotoin6pcb(oso)->in6p_sp, 3707 in6p->in6p_sp)) 3708 printf("tcp_input: could not copy policy\n"); 3709 } 3710 #endif 3711 #endif 3712 3713 /* 3714 * Give the new socket our cached route reference. 3715 */ 3716 if (inp) { 3717 rtcache_copy(&inp->inp_route, &sc->sc_route); 3718 rtcache_free(&sc->sc_route); 3719 } 3720 #ifdef INET6 3721 else { 3722 rtcache_copy(&in6p->in6p_route, &sc->sc_route); 3723 rtcache_free(&sc->sc_route); 3724 } 3725 #endif 3726 3727 am = m_get(M_DONTWAIT, MT_SONAME); /* XXX */ 3728 if (am == NULL) 3729 goto resetandabort; 3730 MCLAIM(am, &tcp_mowner); 3731 am->m_len = src->sa_len; 3732 bcopy(src, mtod(am, void *), src->sa_len); 3733 if (inp) { 3734 if (in_pcbconnect(inp, am, &lwp0)) { 3735 (void) m_free(am); 3736 goto resetandabort; 3737 } 3738 } 3739 #ifdef INET6 3740 else if (in6p) { 3741 if (src->sa_family == AF_INET) { 3742 /* IPv4 packet to AF_INET6 socket */ 3743 struct sockaddr_in6 *sin6; 3744 sin6 = mtod(am, struct sockaddr_in6 *); 3745 am->m_len = sizeof(*sin6); 3746 bzero(sin6, sizeof(*sin6)); 3747 sin6->sin6_family = AF_INET6; 3748 sin6->sin6_len = sizeof(*sin6); 3749 sin6->sin6_port = ((struct sockaddr_in *)src)->sin_port; 3750 sin6->sin6_addr.s6_addr16[5] = htons(0xffff); 3751 bcopy(&((struct sockaddr_in *)src)->sin_addr, 3752 &sin6->sin6_addr.s6_addr32[3], 3753 sizeof(sin6->sin6_addr.s6_addr32[3])); 3754 } 3755 if (in6_pcbconnect(in6p, am, NULL)) { 3756 (void) m_free(am); 3757 goto resetandabort; 3758 } 3759 } 3760 #endif 3761 else { 3762 (void) m_free(am); 3763 goto resetandabort; 3764 } 3765 (void) m_free(am); 3766 3767 if (inp) 3768 tp = intotcpcb(inp); 3769 #ifdef INET6 3770 else if (in6p) 3771 tp = in6totcpcb(in6p); 3772 #endif 3773 else 3774 tp = NULL; 3775 tp->t_flags = sototcpcb(oso)->t_flags & TF_NODELAY; 3776 if (sc->sc_request_r_scale != 15) { 3777 tp->requested_s_scale = sc->sc_requested_s_scale; 3778 tp->request_r_scale = sc->sc_request_r_scale; 3779 tp->snd_scale = sc->sc_requested_s_scale; 3780 tp->rcv_scale = sc->sc_request_r_scale; 3781 tp->t_flags |= TF_REQ_SCALE|TF_RCVD_SCALE; 3782 } 3783 if (sc->sc_flags & SCF_TIMESTAMP) 3784 tp->t_flags |= TF_REQ_TSTMP|TF_RCVD_TSTMP; 3785 tp->ts_timebase = sc->sc_timebase; 3786 3787 tp->t_template = tcp_template(tp); 3788 if (tp->t_template == 0) { 3789 tp = tcp_drop(tp, ENOBUFS); /* destroys socket */ 3790 so = NULL; 3791 m_freem(m); 3792 goto abort; 3793 } 3794 3795 tp->iss = sc->sc_iss; 3796 tp->irs = sc->sc_irs; 3797 tcp_sendseqinit(tp); 3798 tcp_rcvseqinit(tp); 3799 tp->t_state = TCPS_SYN_RECEIVED; 3800 TCP_TIMER_ARM(tp, TCPT_KEEP, tp->t_keepinit); 3801 tcpstat.tcps_accepts++; 3802 3803 if ((sc->sc_flags & SCF_SACK_PERMIT) && tcp_do_sack) 3804 tp->t_flags |= TF_WILL_SACK; 3805 3806 if ((sc->sc_flags & SCF_ECN_PERMIT) && tcp_do_ecn) 3807 tp->t_flags |= TF_ECN_PERMIT; 3808 3809 #ifdef TCP_SIGNATURE 3810 if (sc->sc_flags & SCF_SIGNATURE) 3811 tp->t_flags |= TF_SIGNATURE; 3812 #endif 3813 3814 /* Initialize tp->t_ourmss before we deal with the peer's! */ 3815 tp->t_ourmss = sc->sc_ourmaxseg; 3816 tcp_mss_from_peer(tp, sc->sc_peermaxseg); 3817 3818 /* 3819 * Initialize the initial congestion window. If we 3820 * had to retransmit the SYN,ACK, we must initialize cwnd 3821 * to 1 segment (i.e. the Loss Window). 3822 */ 3823 if (sc->sc_rxtshift) 3824 tp->snd_cwnd = tp->t_peermss; 3825 else { 3826 int ss = tcp_init_win; 3827 #ifdef INET 3828 if (inp != NULL && in_localaddr(inp->inp_faddr)) 3829 ss = tcp_init_win_local; 3830 #endif 3831 #ifdef INET6 3832 if (in6p != NULL && in6_localaddr(&in6p->in6p_faddr)) 3833 ss = tcp_init_win_local; 3834 #endif 3835 tp->snd_cwnd = TCP_INITIAL_WINDOW(ss, tp->t_peermss); 3836 } 3837 3838 tcp_rmx_rtt(tp); 3839 tp->snd_wl1 = sc->sc_irs; 3840 tp->rcv_up = sc->sc_irs + 1; 3841 3842 /* 3843 * This is what whould have happened in tcp_output() when 3844 * the SYN,ACK was sent. 3845 */ 3846 tp->snd_up = tp->snd_una; 3847 tp->snd_max = tp->snd_nxt = tp->iss+1; 3848 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 3849 if (sc->sc_win > 0 && SEQ_GT(tp->rcv_nxt + sc->sc_win, tp->rcv_adv)) 3850 tp->rcv_adv = tp->rcv_nxt + sc->sc_win; 3851 tp->last_ack_sent = tp->rcv_nxt; 3852 tp->t_partialacks = -1; 3853 tp->t_dupacks = 0; 3854 3855 tcpstat.tcps_sc_completed++; 3856 s = splsoftnet(); 3857 syn_cache_put(sc); 3858 splx(s); 3859 return (so); 3860 3861 resetandabort: 3862 (void)tcp_respond(NULL, m, m, th, (tcp_seq)0, th->th_ack, TH_RST); 3863 abort: 3864 if (so != NULL) 3865 (void) soabort(so); 3866 s = splsoftnet(); 3867 syn_cache_put(sc); 3868 splx(s); 3869 tcpstat.tcps_sc_aborted++; 3870 return ((struct socket *)(-1)); 3871 } 3872 3873 /* 3874 * This function is called when we get a RST for a 3875 * non-existent connection, so that we can see if the 3876 * connection is in the syn cache. If it is, zap it. 3877 */ 3878 3879 void 3880 syn_cache_reset(struct sockaddr *src, struct sockaddr *dst, struct tcphdr *th) 3881 { 3882 struct syn_cache *sc; 3883 struct syn_cache_head *scp; 3884 int s = splsoftnet(); 3885 3886 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 3887 splx(s); 3888 return; 3889 } 3890 if (SEQ_LT(th->th_seq, sc->sc_irs) || 3891 SEQ_GT(th->th_seq, sc->sc_irs+1)) { 3892 splx(s); 3893 return; 3894 } 3895 syn_cache_rm(sc); 3896 tcpstat.tcps_sc_reset++; 3897 syn_cache_put(sc); /* calls pool_put but see spl above */ 3898 splx(s); 3899 } 3900 3901 void 3902 syn_cache_unreach(const struct sockaddr *src, const struct sockaddr *dst, 3903 struct tcphdr *th) 3904 { 3905 struct syn_cache *sc; 3906 struct syn_cache_head *scp; 3907 int s; 3908 3909 s = splsoftnet(); 3910 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 3911 splx(s); 3912 return; 3913 } 3914 /* If the sequence number != sc_iss, then it's a bogus ICMP msg */ 3915 if (ntohl (th->th_seq) != sc->sc_iss) { 3916 splx(s); 3917 return; 3918 } 3919 3920 /* 3921 * If we've retransmitted 3 times and this is our second error, 3922 * we remove the entry. Otherwise, we allow it to continue on. 3923 * This prevents us from incorrectly nuking an entry during a 3924 * spurious network outage. 3925 * 3926 * See tcp_notify(). 3927 */ 3928 if ((sc->sc_flags & SCF_UNREACH) == 0 || sc->sc_rxtshift < 3) { 3929 sc->sc_flags |= SCF_UNREACH; 3930 splx(s); 3931 return; 3932 } 3933 3934 syn_cache_rm(sc); 3935 tcpstat.tcps_sc_unreach++; 3936 syn_cache_put(sc); /* calls pool_put but see spl above */ 3937 splx(s); 3938 } 3939 3940 /* 3941 * Given a LISTEN socket and an inbound SYN request, add 3942 * this to the syn cache, and send back a segment: 3943 * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK> 3944 * to the source. 3945 * 3946 * IMPORTANT NOTE: We do _NOT_ ACK data that might accompany the SYN. 3947 * Doing so would require that we hold onto the data and deliver it 3948 * to the application. However, if we are the target of a SYN-flood 3949 * DoS attack, an attacker could send data which would eventually 3950 * consume all available buffer space if it were ACKed. By not ACKing 3951 * the data, we avoid this DoS scenario. 3952 */ 3953 3954 int 3955 syn_cache_add(struct sockaddr *src, struct sockaddr *dst, struct tcphdr *th, 3956 unsigned int hlen, struct socket *so, struct mbuf *m, u_char *optp, 3957 int optlen, struct tcp_opt_info *oi) 3958 { 3959 struct tcpcb tb, *tp; 3960 long win; 3961 struct syn_cache *sc; 3962 struct syn_cache_head *scp; 3963 struct mbuf *ipopts; 3964 struct tcp_opt_info opti; 3965 int s; 3966 3967 tp = sototcpcb(so); 3968 3969 bzero(&opti, sizeof(opti)); 3970 3971 /* 3972 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN 3973 * 3974 * Note this check is performed in tcp_input() very early on. 3975 */ 3976 3977 /* 3978 * Initialize some local state. 3979 */ 3980 win = sbspace(&so->so_rcv); 3981 if (win > TCP_MAXWIN) 3982 win = TCP_MAXWIN; 3983 3984 switch (src->sa_family) { 3985 #ifdef INET 3986 case AF_INET: 3987 /* 3988 * Remember the IP options, if any. 3989 */ 3990 ipopts = ip_srcroute(); 3991 break; 3992 #endif 3993 default: 3994 ipopts = NULL; 3995 } 3996 3997 #ifdef TCP_SIGNATURE 3998 if (optp || (tp->t_flags & TF_SIGNATURE)) 3999 #else 4000 if (optp) 4001 #endif 4002 { 4003 tb.t_flags = tcp_do_rfc1323 ? (TF_REQ_SCALE|TF_REQ_TSTMP) : 0; 4004 #ifdef TCP_SIGNATURE 4005 tb.t_flags |= (tp->t_flags & TF_SIGNATURE); 4006 #endif 4007 tb.t_state = TCPS_LISTEN; 4008 if (tcp_dooptions(&tb, optp, optlen, th, m, m->m_pkthdr.len - 4009 sizeof(struct tcphdr) - optlen - hlen, oi) < 0) 4010 return (0); 4011 } else 4012 tb.t_flags = 0; 4013 4014 /* 4015 * See if we already have an entry for this connection. 4016 * If we do, resend the SYN,ACK. We do not count this 4017 * as a retransmission (XXX though maybe we should). 4018 */ 4019 if ((sc = syn_cache_lookup(src, dst, &scp)) != NULL) { 4020 tcpstat.tcps_sc_dupesyn++; 4021 if (ipopts) { 4022 /* 4023 * If we were remembering a previous source route, 4024 * forget it and use the new one we've been given. 4025 */ 4026 if (sc->sc_ipopts) 4027 (void) m_free(sc->sc_ipopts); 4028 sc->sc_ipopts = ipopts; 4029 } 4030 sc->sc_timestamp = tb.ts_recent; 4031 if (syn_cache_respond(sc, m) == 0) { 4032 tcpstat.tcps_sndacks++; 4033 tcpstat.tcps_sndtotal++; 4034 } 4035 return (1); 4036 } 4037 4038 s = splsoftnet(); 4039 sc = pool_get(&syn_cache_pool, PR_NOWAIT); 4040 splx(s); 4041 if (sc == NULL) { 4042 if (ipopts) 4043 (void) m_free(ipopts); 4044 return (0); 4045 } 4046 4047 /* 4048 * Fill in the cache, and put the necessary IP and TCP 4049 * options into the reply. 4050 */ 4051 bzero(sc, sizeof(struct syn_cache)); 4052 callout_init(&sc->sc_timer, 0); 4053 bcopy(src, &sc->sc_src, src->sa_len); 4054 bcopy(dst, &sc->sc_dst, dst->sa_len); 4055 sc->sc_flags = 0; 4056 sc->sc_ipopts = ipopts; 4057 sc->sc_irs = th->th_seq; 4058 switch (src->sa_family) { 4059 #ifdef INET 4060 case AF_INET: 4061 { 4062 struct sockaddr_in *srcin = (void *) src; 4063 struct sockaddr_in *dstin = (void *) dst; 4064 4065 sc->sc_iss = tcp_new_iss1(&dstin->sin_addr, 4066 &srcin->sin_addr, dstin->sin_port, 4067 srcin->sin_port, sizeof(dstin->sin_addr), 0); 4068 break; 4069 } 4070 #endif /* INET */ 4071 #ifdef INET6 4072 case AF_INET6: 4073 { 4074 struct sockaddr_in6 *srcin6 = (void *) src; 4075 struct sockaddr_in6 *dstin6 = (void *) dst; 4076 4077 sc->sc_iss = tcp_new_iss1(&dstin6->sin6_addr, 4078 &srcin6->sin6_addr, dstin6->sin6_port, 4079 srcin6->sin6_port, sizeof(dstin6->sin6_addr), 0); 4080 break; 4081 } 4082 #endif /* INET6 */ 4083 } 4084 sc->sc_peermaxseg = oi->maxseg; 4085 sc->sc_ourmaxseg = tcp_mss_to_advertise(m->m_flags & M_PKTHDR ? 4086 m->m_pkthdr.rcvif : NULL, 4087 sc->sc_src.sa.sa_family); 4088 sc->sc_win = win; 4089 sc->sc_timebase = tcp_now - 1; /* see tcp_newtcpcb() */ 4090 sc->sc_timestamp = tb.ts_recent; 4091 if ((tb.t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP)) == 4092 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) 4093 sc->sc_flags |= SCF_TIMESTAMP; 4094 if ((tb.t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 4095 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 4096 sc->sc_requested_s_scale = tb.requested_s_scale; 4097 sc->sc_request_r_scale = 0; 4098 /* 4099 * Pick the smallest possible scaling factor that 4100 * will still allow us to scale up to sb_max. 4101 * 4102 * We do this because there are broken firewalls that 4103 * will corrupt the window scale option, leading to 4104 * the other endpoint believing that our advertised 4105 * window is unscaled. At scale factors larger than 4106 * 5 the unscaled window will drop below 1500 bytes, 4107 * leading to serious problems when traversing these 4108 * broken firewalls. 4109 * 4110 * With the default sbmax of 256K, a scale factor 4111 * of 3 will be chosen by this algorithm. Those who 4112 * choose a larger sbmax should watch out 4113 * for the compatiblity problems mentioned above. 4114 * 4115 * RFC1323: The Window field in a SYN (i.e., a <SYN> 4116 * or <SYN,ACK>) segment itself is never scaled. 4117 */ 4118 while (sc->sc_request_r_scale < TCP_MAX_WINSHIFT && 4119 (TCP_MAXWIN << sc->sc_request_r_scale) < sb_max) 4120 sc->sc_request_r_scale++; 4121 } else { 4122 sc->sc_requested_s_scale = 15; 4123 sc->sc_request_r_scale = 15; 4124 } 4125 if ((tb.t_flags & TF_SACK_PERMIT) && tcp_do_sack) 4126 sc->sc_flags |= SCF_SACK_PERMIT; 4127 4128 /* 4129 * ECN setup packet recieved. 4130 */ 4131 if ((th->th_flags & (TH_ECE|TH_CWR)) && tcp_do_ecn) 4132 sc->sc_flags |= SCF_ECN_PERMIT; 4133 4134 #ifdef TCP_SIGNATURE 4135 if (tb.t_flags & TF_SIGNATURE) 4136 sc->sc_flags |= SCF_SIGNATURE; 4137 #endif 4138 sc->sc_tp = tp; 4139 if (syn_cache_respond(sc, m) == 0) { 4140 syn_cache_insert(sc, tp); 4141 tcpstat.tcps_sndacks++; 4142 tcpstat.tcps_sndtotal++; 4143 } else { 4144 s = splsoftnet(); 4145 syn_cache_put(sc); 4146 splx(s); 4147 tcpstat.tcps_sc_dropped++; 4148 } 4149 return (1); 4150 } 4151 4152 int 4153 syn_cache_respond(struct syn_cache *sc, struct mbuf *m) 4154 { 4155 #ifdef INET6 4156 struct rtentry *rt; 4157 #endif 4158 struct route *ro; 4159 u_int8_t *optp; 4160 int optlen, error; 4161 u_int16_t tlen; 4162 struct ip *ip = NULL; 4163 #ifdef INET6 4164 struct ip6_hdr *ip6 = NULL; 4165 #endif 4166 struct tcpcb *tp = NULL; 4167 struct tcphdr *th; 4168 u_int hlen; 4169 struct socket *so; 4170 4171 ro = &sc->sc_route; 4172 switch (sc->sc_src.sa.sa_family) { 4173 case AF_INET: 4174 hlen = sizeof(struct ip); 4175 break; 4176 #ifdef INET6 4177 case AF_INET6: 4178 hlen = sizeof(struct ip6_hdr); 4179 break; 4180 #endif 4181 default: 4182 if (m) 4183 m_freem(m); 4184 return (EAFNOSUPPORT); 4185 } 4186 4187 /* Compute the size of the TCP options. */ 4188 optlen = 4 + (sc->sc_request_r_scale != 15 ? 4 : 0) + 4189 ((sc->sc_flags & SCF_SACK_PERMIT) ? (TCPOLEN_SACK_PERMITTED + 2) : 0) + 4190 #ifdef TCP_SIGNATURE 4191 ((sc->sc_flags & SCF_SIGNATURE) ? (TCPOLEN_SIGNATURE + 2) : 0) + 4192 #endif 4193 ((sc->sc_flags & SCF_TIMESTAMP) ? TCPOLEN_TSTAMP_APPA : 0); 4194 4195 tlen = hlen + sizeof(struct tcphdr) + optlen; 4196 4197 /* 4198 * Create the IP+TCP header from scratch. 4199 */ 4200 if (m) 4201 m_freem(m); 4202 #ifdef DIAGNOSTIC 4203 if (max_linkhdr + tlen > MCLBYTES) 4204 return (ENOBUFS); 4205 #endif 4206 MGETHDR(m, M_DONTWAIT, MT_DATA); 4207 if (m && tlen > MHLEN) { 4208 MCLGET(m, M_DONTWAIT); 4209 if ((m->m_flags & M_EXT) == 0) { 4210 m_freem(m); 4211 m = NULL; 4212 } 4213 } 4214 if (m == NULL) 4215 return (ENOBUFS); 4216 MCLAIM(m, &tcp_tx_mowner); 4217 4218 /* Fixup the mbuf. */ 4219 m->m_data += max_linkhdr; 4220 m->m_len = m->m_pkthdr.len = tlen; 4221 if (sc->sc_tp) { 4222 tp = sc->sc_tp; 4223 if (tp->t_inpcb) 4224 so = tp->t_inpcb->inp_socket; 4225 #ifdef INET6 4226 else if (tp->t_in6pcb) 4227 so = tp->t_in6pcb->in6p_socket; 4228 #endif 4229 else 4230 so = NULL; 4231 } else 4232 so = NULL; 4233 m->m_pkthdr.rcvif = NULL; 4234 memset(mtod(m, u_char *), 0, tlen); 4235 4236 switch (sc->sc_src.sa.sa_family) { 4237 case AF_INET: 4238 ip = mtod(m, struct ip *); 4239 ip->ip_v = 4; 4240 ip->ip_dst = sc->sc_src.sin.sin_addr; 4241 ip->ip_src = sc->sc_dst.sin.sin_addr; 4242 ip->ip_p = IPPROTO_TCP; 4243 th = (struct tcphdr *)(ip + 1); 4244 th->th_dport = sc->sc_src.sin.sin_port; 4245 th->th_sport = sc->sc_dst.sin.sin_port; 4246 break; 4247 #ifdef INET6 4248 case AF_INET6: 4249 ip6 = mtod(m, struct ip6_hdr *); 4250 ip6->ip6_vfc = IPV6_VERSION; 4251 ip6->ip6_dst = sc->sc_src.sin6.sin6_addr; 4252 ip6->ip6_src = sc->sc_dst.sin6.sin6_addr; 4253 ip6->ip6_nxt = IPPROTO_TCP; 4254 /* ip6_plen will be updated in ip6_output() */ 4255 th = (struct tcphdr *)(ip6 + 1); 4256 th->th_dport = sc->sc_src.sin6.sin6_port; 4257 th->th_sport = sc->sc_dst.sin6.sin6_port; 4258 break; 4259 #endif 4260 default: 4261 th = NULL; 4262 } 4263 4264 th->th_seq = htonl(sc->sc_iss); 4265 th->th_ack = htonl(sc->sc_irs + 1); 4266 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 4267 th->th_flags = TH_SYN|TH_ACK; 4268 th->th_win = htons(sc->sc_win); 4269 /* th_sum already 0 */ 4270 /* th_urp already 0 */ 4271 4272 /* Tack on the TCP options. */ 4273 optp = (u_int8_t *)(th + 1); 4274 *optp++ = TCPOPT_MAXSEG; 4275 *optp++ = 4; 4276 *optp++ = (sc->sc_ourmaxseg >> 8) & 0xff; 4277 *optp++ = sc->sc_ourmaxseg & 0xff; 4278 4279 if (sc->sc_request_r_scale != 15) { 4280 *((u_int32_t *)optp) = htonl(TCPOPT_NOP << 24 | 4281 TCPOPT_WINDOW << 16 | TCPOLEN_WINDOW << 8 | 4282 sc->sc_request_r_scale); 4283 optp += 4; 4284 } 4285 4286 if (sc->sc_flags & SCF_TIMESTAMP) { 4287 u_int32_t *lp = (u_int32_t *)(optp); 4288 /* Form timestamp option as shown in appendix A of RFC 1323. */ 4289 *lp++ = htonl(TCPOPT_TSTAMP_HDR); 4290 *lp++ = htonl(SYN_CACHE_TIMESTAMP(sc)); 4291 *lp = htonl(sc->sc_timestamp); 4292 optp += TCPOLEN_TSTAMP_APPA; 4293 } 4294 4295 if (sc->sc_flags & SCF_SACK_PERMIT) { 4296 u_int8_t *p = optp; 4297 4298 /* Let the peer know that we will SACK. */ 4299 p[0] = TCPOPT_SACK_PERMITTED; 4300 p[1] = 2; 4301 p[2] = TCPOPT_NOP; 4302 p[3] = TCPOPT_NOP; 4303 optp += 4; 4304 } 4305 4306 /* 4307 * Send ECN SYN-ACK setup packet. 4308 * Routes can be asymetric, so, even if we receive a packet 4309 * with ECE and CWR set, we must not assume no one will block 4310 * the ECE packet we are about to send. 4311 */ 4312 if ((sc->sc_flags & SCF_ECN_PERMIT) && tp && 4313 SEQ_GEQ(tp->snd_nxt, tp->snd_max)) { 4314 th->th_flags |= TH_ECE; 4315 tcpstat.tcps_ecn_shs++; 4316 4317 /* 4318 * draft-ietf-tcpm-ecnsyn-00.txt 4319 * 4320 * "[...] a TCP node MAY respond to an ECN-setup 4321 * SYN packet by setting ECT in the responding 4322 * ECN-setup SYN/ACK packet, indicating to routers 4323 * that the SYN/ACK packet is ECN-Capable. 4324 * This allows a congested router along the path 4325 * to mark the packet instead of dropping the 4326 * packet as an indication of congestion." 4327 * 4328 * "[...] There can be a great benefit in setting 4329 * an ECN-capable codepoint in SYN/ACK packets [...] 4330 * Congestion is most likely to occur in 4331 * the server-to-client direction. As a result, 4332 * setting an ECN-capable codepoint in SYN/ACK 4333 * packets can reduce the occurence of three-second 4334 * retransmit timeouts resulting from the drop 4335 * of SYN/ACK packets." 4336 * 4337 * Page 4 and 6, January 2006. 4338 */ 4339 4340 switch (sc->sc_src.sa.sa_family) { 4341 #ifdef INET 4342 case AF_INET: 4343 ip->ip_tos |= IPTOS_ECN_ECT0; 4344 break; 4345 #endif 4346 #ifdef INET6 4347 case AF_INET6: 4348 ip6->ip6_flow |= htonl(IPTOS_ECN_ECT0 << 20); 4349 break; 4350 #endif 4351 } 4352 tcpstat.tcps_ecn_ect++; 4353 } 4354 4355 #ifdef TCP_SIGNATURE 4356 if (sc->sc_flags & SCF_SIGNATURE) { 4357 struct secasvar *sav; 4358 u_int8_t *sigp; 4359 4360 sav = tcp_signature_getsav(m, th); 4361 4362 if (sav == NULL) { 4363 if (m) 4364 m_freem(m); 4365 return (EPERM); 4366 } 4367 4368 *optp++ = TCPOPT_SIGNATURE; 4369 *optp++ = TCPOLEN_SIGNATURE; 4370 sigp = optp; 4371 bzero(optp, TCP_SIGLEN); 4372 optp += TCP_SIGLEN; 4373 *optp++ = TCPOPT_NOP; 4374 *optp++ = TCPOPT_EOL; 4375 4376 (void)tcp_signature(m, th, hlen, sav, sigp); 4377 4378 key_sa_recordxfer(sav, m); 4379 #ifdef FAST_IPSEC 4380 KEY_FREESAV(&sav); 4381 #else 4382 key_freesav(sav); 4383 #endif 4384 } 4385 #endif 4386 4387 /* Compute the packet's checksum. */ 4388 switch (sc->sc_src.sa.sa_family) { 4389 case AF_INET: 4390 ip->ip_len = htons(tlen - hlen); 4391 th->th_sum = 0; 4392 th->th_sum = in4_cksum(m, IPPROTO_TCP, hlen, tlen - hlen); 4393 break; 4394 #ifdef INET6 4395 case AF_INET6: 4396 ip6->ip6_plen = htons(tlen - hlen); 4397 th->th_sum = 0; 4398 th->th_sum = in6_cksum(m, IPPROTO_TCP, hlen, tlen - hlen); 4399 break; 4400 #endif 4401 } 4402 4403 /* 4404 * Fill in some straggling IP bits. Note the stack expects 4405 * ip_len to be in host order, for convenience. 4406 */ 4407 switch (sc->sc_src.sa.sa_family) { 4408 #ifdef INET 4409 case AF_INET: 4410 ip->ip_len = htons(tlen); 4411 ip->ip_ttl = ip_defttl; 4412 /* XXX tos? */ 4413 break; 4414 #endif 4415 #ifdef INET6 4416 case AF_INET6: 4417 ip6->ip6_vfc &= ~IPV6_VERSION_MASK; 4418 ip6->ip6_vfc |= IPV6_VERSION; 4419 ip6->ip6_plen = htons(tlen - hlen); 4420 /* ip6_hlim will be initialized afterwards */ 4421 /* XXX flowlabel? */ 4422 break; 4423 #endif 4424 } 4425 4426 /* XXX use IPsec policy on listening socket, on SYN ACK */ 4427 tp = sc->sc_tp; 4428 4429 switch (sc->sc_src.sa.sa_family) { 4430 #ifdef INET 4431 case AF_INET: 4432 error = ip_output(m, sc->sc_ipopts, ro, 4433 (ip_mtudisc ? IP_MTUDISC : 0), 4434 (struct ip_moptions *)NULL, so); 4435 break; 4436 #endif 4437 #ifdef INET6 4438 case AF_INET6: 4439 ip6->ip6_hlim = in6_selecthlim(NULL, 4440 (rt = rtcache_validate(ro)) != NULL ? rt->rt_ifp 4441 : NULL); 4442 4443 error = ip6_output(m, NULL /*XXX*/, ro, 0, NULL, so, NULL); 4444 break; 4445 #endif 4446 default: 4447 error = EAFNOSUPPORT; 4448 break; 4449 } 4450 return (error); 4451 } 4452