1 /* $NetBSD: tcp_input.c,v 1.186 2003/10/24 10:25:40 ragge 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 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 * 80 * Redistribution and use in source and binary forms, with or without 81 * modification, are permitted provided that the following conditions 82 * are met: 83 * 1. Redistributions of source code must retain the above copyright 84 * notice, this list of conditions and the following disclaimer. 85 * 2. Redistributions in binary form must reproduce the above copyright 86 * notice, this list of conditions and the following disclaimer in the 87 * documentation and/or other materials provided with the distribution. 88 * 3. All advertising materials mentioning features or use of this software 89 * must display the following acknowledgement: 90 * This product includes software developed by the NetBSD 91 * Foundation, Inc. and its contributors. 92 * 4. Neither the name of The NetBSD Foundation nor the names of its 93 * contributors may be used to endorse or promote products derived 94 * from this software without specific prior written permission. 95 * 96 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 97 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 98 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 99 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 100 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 101 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 102 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 103 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 104 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 105 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 106 * POSSIBILITY OF SUCH DAMAGE. 107 */ 108 109 /* 110 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995 111 * The Regents of the University of California. All rights reserved. 112 * 113 * Redistribution and use in source and binary forms, with or without 114 * modification, are permitted provided that the following conditions 115 * are met: 116 * 1. Redistributions of source code must retain the above copyright 117 * notice, this list of conditions and the following disclaimer. 118 * 2. Redistributions in binary form must reproduce the above copyright 119 * notice, this list of conditions and the following disclaimer in the 120 * documentation and/or other materials provided with the distribution. 121 * 3. Neither the name of the University nor the names of its contributors 122 * may be used to endorse or promote products derived from this software 123 * without specific prior written permission. 124 * 125 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 126 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 127 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 128 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 129 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 130 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 131 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 132 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 133 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 134 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 135 * SUCH DAMAGE. 136 * 137 * @(#)tcp_input.c 8.12 (Berkeley) 5/24/95 138 */ 139 140 /* 141 * TODO list for SYN cache stuff: 142 * 143 * Find room for a "state" field, which is needed to keep a 144 * compressed state for TIME_WAIT TCBs. It's been noted already 145 * that this is fairly important for very high-volume web and 146 * mail servers, which use a large number of short-lived 147 * connections. 148 */ 149 150 #include <sys/cdefs.h> 151 __KERNEL_RCSID(0, "$NetBSD: tcp_input.c,v 1.186 2003/10/24 10:25:40 ragge Exp $"); 152 153 #include "opt_inet.h" 154 #include "opt_ipsec.h" 155 #include "opt_inet_csum.h" 156 #include "opt_tcp_debug.h" 157 158 #include <sys/param.h> 159 #include <sys/systm.h> 160 #include <sys/malloc.h> 161 #include <sys/mbuf.h> 162 #include <sys/protosw.h> 163 #include <sys/socket.h> 164 #include <sys/socketvar.h> 165 #include <sys/errno.h> 166 #include <sys/syslog.h> 167 #include <sys/pool.h> 168 #include <sys/domain.h> 169 #include <sys/kernel.h> 170 171 #include <net/if.h> 172 #include <net/route.h> 173 #include <net/if_types.h> 174 175 #include <netinet/in.h> 176 #include <netinet/in_systm.h> 177 #include <netinet/ip.h> 178 #include <netinet/in_pcb.h> 179 #include <netinet/in_var.h> 180 #include <netinet/ip_var.h> 181 182 #ifdef INET6 183 #ifndef INET 184 #include <netinet/in.h> 185 #endif 186 #include <netinet/ip6.h> 187 #include <netinet6/ip6_var.h> 188 #include <netinet6/in6_pcb.h> 189 #include <netinet6/ip6_var.h> 190 #include <netinet6/in6_var.h> 191 #include <netinet/icmp6.h> 192 #include <netinet6/nd6.h> 193 #endif 194 195 #ifndef INET6 196 /* always need ip6.h for IP6_EXTHDR_GET */ 197 #include <netinet/ip6.h> 198 #endif 199 200 #include <netinet/tcp.h> 201 #include <netinet/tcp_fsm.h> 202 #include <netinet/tcp_seq.h> 203 #include <netinet/tcp_timer.h> 204 #include <netinet/tcp_var.h> 205 #include <netinet/tcpip.h> 206 #include <netinet/tcp_debug.h> 207 208 #include <machine/stdarg.h> 209 210 #ifdef IPSEC 211 #include <netinet6/ipsec.h> 212 #include <netkey/key.h> 213 #endif /*IPSEC*/ 214 #ifdef INET6 215 #include "faith.h" 216 #if defined(NFAITH) && NFAITH > 0 217 #include <net/if_faith.h> 218 #endif 219 #endif /* IPSEC */ 220 221 #ifdef FAST_IPSEC 222 #include <netipsec/ipsec.h> 223 #include <netipsec/key.h> 224 #endif /* FAST_IPSEC*/ 225 226 227 int tcprexmtthresh = 3; 228 int tcp_log_refused; 229 230 static int tcp_rst_ppslim_count = 0; 231 static struct timeval tcp_rst_ppslim_last; 232 233 #define TCP_PAWS_IDLE (24 * 24 * 60 * 60 * PR_SLOWHZ) 234 235 /* for modulo comparisons of timestamps */ 236 #define TSTMP_LT(a,b) ((int)((a)-(b)) < 0) 237 #define TSTMP_GEQ(a,b) ((int)((a)-(b)) >= 0) 238 239 /* 240 * Neighbor Discovery, Neighbor Unreachability Detection Upper layer hint. 241 */ 242 #ifdef INET6 243 #define ND6_HINT(tp) \ 244 do { \ 245 if (tp && tp->t_in6pcb && tp->t_family == AF_INET6 \ 246 && tp->t_in6pcb->in6p_route.ro_rt) { \ 247 nd6_nud_hint(tp->t_in6pcb->in6p_route.ro_rt, NULL, 0); \ 248 } \ 249 } while (/*CONSTCOND*/ 0) 250 #else 251 #define ND6_HINT(tp) 252 #endif 253 254 /* 255 * Macro to compute ACK transmission behavior. Delay the ACK unless 256 * we have already delayed an ACK (must send an ACK every two segments). 257 * We also ACK immediately if we received a PUSH and the ACK-on-PUSH 258 * option is enabled. 259 */ 260 #define TCP_SETUP_ACK(tp, th) \ 261 do { \ 262 if ((tp)->t_flags & TF_DELACK || \ 263 (tcp_ack_on_push && (th)->th_flags & TH_PUSH)) \ 264 tp->t_flags |= TF_ACKNOW; \ 265 else \ 266 TCP_SET_DELACK(tp); \ 267 } while (/*CONSTCOND*/ 0) 268 269 /* 270 * Convert TCP protocol fields to host order for easier processing. 271 */ 272 #define TCP_FIELDS_TO_HOST(th) \ 273 do { \ 274 NTOHL((th)->th_seq); \ 275 NTOHL((th)->th_ack); \ 276 NTOHS((th)->th_win); \ 277 NTOHS((th)->th_urp); \ 278 } while (/*CONSTCOND*/ 0) 279 280 /* 281 * ... and reverse the above. 282 */ 283 #define TCP_FIELDS_TO_NET(th) \ 284 do { \ 285 HTONL((th)->th_seq); \ 286 HTONL((th)->th_ack); \ 287 HTONS((th)->th_win); \ 288 HTONS((th)->th_urp); \ 289 } while (/*CONSTCOND*/ 0) 290 291 #ifdef TCP_CSUM_COUNTERS 292 #include <sys/device.h> 293 294 extern struct evcnt tcp_hwcsum_ok; 295 extern struct evcnt tcp_hwcsum_bad; 296 extern struct evcnt tcp_hwcsum_data; 297 extern struct evcnt tcp_swcsum; 298 299 #define TCP_CSUM_COUNTER_INCR(ev) (ev)->ev_count++ 300 301 #else 302 303 #define TCP_CSUM_COUNTER_INCR(ev) /* nothing */ 304 305 #endif /* TCP_CSUM_COUNTERS */ 306 307 #ifdef TCP_REASS_COUNTERS 308 #include <sys/device.h> 309 310 extern struct evcnt tcp_reass_; 311 extern struct evcnt tcp_reass_empty; 312 extern struct evcnt tcp_reass_iteration[8]; 313 extern struct evcnt tcp_reass_prependfirst; 314 extern struct evcnt tcp_reass_prepend; 315 extern struct evcnt tcp_reass_insert; 316 extern struct evcnt tcp_reass_inserttail; 317 extern struct evcnt tcp_reass_append; 318 extern struct evcnt tcp_reass_appendtail; 319 extern struct evcnt tcp_reass_overlaptail; 320 extern struct evcnt tcp_reass_overlapfront; 321 extern struct evcnt tcp_reass_segdup; 322 extern struct evcnt tcp_reass_fragdup; 323 324 #define TCP_REASS_COUNTER_INCR(ev) (ev)->ev_count++ 325 326 #else 327 328 #define TCP_REASS_COUNTER_INCR(ev) /* nothing */ 329 330 #endif /* TCP_REASS_COUNTERS */ 331 332 #ifdef INET 333 static void tcp4_log_refused __P((const struct ip *, const struct tcphdr *)); 334 #endif 335 #ifdef INET6 336 static void tcp6_log_refused 337 __P((const struct ip6_hdr *, const struct tcphdr *)); 338 #endif 339 340 int 341 tcp_reass(tp, th, m, tlen) 342 struct tcpcb *tp; 343 struct tcphdr *th; 344 struct mbuf *m; 345 int *tlen; 346 { 347 struct ipqent *p, *q, *nq, *tiqe = NULL; 348 struct socket *so = NULL; 349 int pkt_flags; 350 tcp_seq pkt_seq; 351 unsigned pkt_len; 352 u_long rcvpartdupbyte = 0; 353 u_long rcvoobyte; 354 #ifdef TCP_REASS_COUNTERS 355 u_int count = 0; 356 #endif 357 358 if (tp->t_inpcb) 359 so = tp->t_inpcb->inp_socket; 360 #ifdef INET6 361 else if (tp->t_in6pcb) 362 so = tp->t_in6pcb->in6p_socket; 363 #endif 364 365 TCP_REASS_LOCK_CHECK(tp); 366 367 /* 368 * Call with th==0 after become established to 369 * force pre-ESTABLISHED data up to user socket. 370 */ 371 if (th == 0) 372 goto present; 373 374 rcvoobyte = *tlen; 375 /* 376 * Copy these to local variables because the tcpiphdr 377 * gets munged while we are collapsing mbufs. 378 */ 379 pkt_seq = th->th_seq; 380 pkt_len = *tlen; 381 pkt_flags = th->th_flags; 382 383 TCP_REASS_COUNTER_INCR(&tcp_reass_); 384 385 if ((p = TAILQ_LAST(&tp->segq, ipqehead)) != NULL) { 386 /* 387 * When we miss a packet, the vast majority of time we get 388 * packets that follow it in order. So optimize for that. 389 */ 390 if (pkt_seq == p->ipqe_seq + p->ipqe_len) { 391 p->ipqe_len += pkt_len; 392 p->ipqe_flags |= pkt_flags; 393 m_cat(p->ipqe_m, m); 394 tiqe = p; 395 TAILQ_REMOVE(&tp->timeq, p, ipqe_timeq); 396 TCP_REASS_COUNTER_INCR(&tcp_reass_appendtail); 397 goto skip_replacement; 398 } 399 /* 400 * While we're here, if the pkt is completely beyond 401 * anything we have, just insert it at the tail. 402 */ 403 if (SEQ_GT(pkt_seq, p->ipqe_seq + p->ipqe_len)) { 404 TCP_REASS_COUNTER_INCR(&tcp_reass_inserttail); 405 goto insert_it; 406 } 407 } 408 409 q = TAILQ_FIRST(&tp->segq); 410 411 if (q != NULL) { 412 /* 413 * If this segment immediately precedes the first out-of-order 414 * block, simply slap the segment in front of it and (mostly) 415 * skip the complicated logic. 416 */ 417 if (pkt_seq + pkt_len == q->ipqe_seq) { 418 q->ipqe_seq = pkt_seq; 419 q->ipqe_len += pkt_len; 420 q->ipqe_flags |= pkt_flags; 421 m_cat(m, q->ipqe_m); 422 q->ipqe_m = m; 423 tiqe = q; 424 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 425 TCP_REASS_COUNTER_INCR(&tcp_reass_prependfirst); 426 goto skip_replacement; 427 } 428 } else { 429 TCP_REASS_COUNTER_INCR(&tcp_reass_empty); 430 } 431 432 /* 433 * Find a segment which begins after this one does. 434 */ 435 for (p = NULL; q != NULL; q = nq) { 436 nq = TAILQ_NEXT(q, ipqe_q); 437 #ifdef TCP_REASS_COUNTERS 438 count++; 439 #endif 440 /* 441 * If the received segment is just right after this 442 * fragment, merge the two together and then check 443 * for further overlaps. 444 */ 445 if (q->ipqe_seq + q->ipqe_len == pkt_seq) { 446 #ifdef TCPREASS_DEBUG 447 printf("tcp_reass[%p]: concat %u:%u(%u) to %u:%u(%u)\n", 448 tp, pkt_seq, pkt_seq + pkt_len, pkt_len, 449 q->ipqe_seq, q->ipqe_seq + q->ipqe_len, q->ipqe_len); 450 #endif 451 pkt_len += q->ipqe_len; 452 pkt_flags |= q->ipqe_flags; 453 pkt_seq = q->ipqe_seq; 454 m_cat(q->ipqe_m, m); 455 m = q->ipqe_m; 456 TCP_REASS_COUNTER_INCR(&tcp_reass_append); 457 goto free_ipqe; 458 } 459 /* 460 * If the received segment is completely past this 461 * fragment, we need to go the next fragment. 462 */ 463 if (SEQ_LT(q->ipqe_seq + q->ipqe_len, pkt_seq)) { 464 p = q; 465 continue; 466 } 467 /* 468 * If the fragment is past the received segment, 469 * it (or any following) can't be concatenated. 470 */ 471 if (SEQ_GT(q->ipqe_seq, pkt_seq + pkt_len)) { 472 TCP_REASS_COUNTER_INCR(&tcp_reass_insert); 473 break; 474 } 475 476 /* 477 * We've received all the data in this segment before. 478 * mark it as a duplicate and return. 479 */ 480 if (SEQ_LEQ(q->ipqe_seq, pkt_seq) && 481 SEQ_GEQ(q->ipqe_seq + q->ipqe_len, pkt_seq + pkt_len)) { 482 tcpstat.tcps_rcvduppack++; 483 tcpstat.tcps_rcvdupbyte += pkt_len; 484 m_freem(m); 485 if (tiqe != NULL) 486 pool_put(&ipqent_pool, tiqe); 487 TCP_REASS_COUNTER_INCR(&tcp_reass_segdup); 488 return (0); 489 } 490 /* 491 * Received segment completely overlaps this fragment 492 * so we drop the fragment (this keeps the temporal 493 * ordering of segments correct). 494 */ 495 if (SEQ_GEQ(q->ipqe_seq, pkt_seq) && 496 SEQ_LEQ(q->ipqe_seq + q->ipqe_len, pkt_seq + pkt_len)) { 497 rcvpartdupbyte += q->ipqe_len; 498 m_freem(q->ipqe_m); 499 TCP_REASS_COUNTER_INCR(&tcp_reass_fragdup); 500 goto free_ipqe; 501 } 502 /* 503 * RX'ed segment extends past the end of the 504 * fragment. Drop the overlapping bytes. Then 505 * merge the fragment and segment then treat as 506 * a longer received packet. 507 */ 508 if (SEQ_LT(q->ipqe_seq, pkt_seq) 509 && SEQ_GT(q->ipqe_seq + q->ipqe_len, pkt_seq)) { 510 int overlap = q->ipqe_seq + q->ipqe_len - pkt_seq; 511 #ifdef TCPREASS_DEBUG 512 printf("tcp_reass[%p]: trim starting %d bytes of %u:%u(%u)\n", 513 tp, overlap, 514 pkt_seq, pkt_seq + pkt_len, pkt_len); 515 #endif 516 m_adj(m, overlap); 517 rcvpartdupbyte += overlap; 518 m_cat(q->ipqe_m, m); 519 m = q->ipqe_m; 520 pkt_seq = q->ipqe_seq; 521 pkt_len += q->ipqe_len - overlap; 522 rcvoobyte -= overlap; 523 TCP_REASS_COUNTER_INCR(&tcp_reass_overlaptail); 524 goto free_ipqe; 525 } 526 /* 527 * RX'ed segment extends past the front of the 528 * fragment. Drop the overlapping bytes on the 529 * received packet. The packet will then be 530 * contatentated with this fragment a bit later. 531 */ 532 if (SEQ_GT(q->ipqe_seq, pkt_seq) 533 && SEQ_LT(q->ipqe_seq, pkt_seq + pkt_len)) { 534 int overlap = pkt_seq + pkt_len - q->ipqe_seq; 535 #ifdef TCPREASS_DEBUG 536 printf("tcp_reass[%p]: trim trailing %d bytes of %u:%u(%u)\n", 537 tp, overlap, 538 pkt_seq, pkt_seq + pkt_len, pkt_len); 539 #endif 540 m_adj(m, -overlap); 541 pkt_len -= overlap; 542 rcvpartdupbyte += overlap; 543 TCP_REASS_COUNTER_INCR(&tcp_reass_overlapfront); 544 rcvoobyte -= overlap; 545 } 546 /* 547 * If the received segment immediates precedes this 548 * fragment then tack the fragment onto this segment 549 * and reinsert the data. 550 */ 551 if (q->ipqe_seq == pkt_seq + pkt_len) { 552 #ifdef TCPREASS_DEBUG 553 printf("tcp_reass[%p]: append %u:%u(%u) to %u:%u(%u)\n", 554 tp, q->ipqe_seq, q->ipqe_seq + q->ipqe_len, q->ipqe_len, 555 pkt_seq, pkt_seq + pkt_len, pkt_len); 556 #endif 557 pkt_len += q->ipqe_len; 558 pkt_flags |= q->ipqe_flags; 559 m_cat(m, q->ipqe_m); 560 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 561 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 562 if (tiqe == NULL) { 563 tiqe = q; 564 } else { 565 pool_put(&ipqent_pool, q); 566 } 567 TCP_REASS_COUNTER_INCR(&tcp_reass_prepend); 568 break; 569 } 570 /* 571 * If the fragment is before the segment, remember it. 572 * When this loop is terminated, p will contain the 573 * pointer to fragment that is right before the received 574 * segment. 575 */ 576 if (SEQ_LEQ(q->ipqe_seq, pkt_seq)) 577 p = q; 578 579 continue; 580 581 /* 582 * This is a common operation. It also will allow 583 * to save doing a malloc/free in most instances. 584 */ 585 free_ipqe: 586 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 587 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 588 if (tiqe == NULL) { 589 tiqe = q; 590 } else { 591 pool_put(&ipqent_pool, q); 592 } 593 } 594 595 #ifdef TCP_REASS_COUNTERS 596 if (count > 7) 597 TCP_REASS_COUNTER_INCR(&tcp_reass_iteration[0]); 598 else if (count > 0) 599 TCP_REASS_COUNTER_INCR(&tcp_reass_iteration[count]); 600 #endif 601 602 insert_it: 603 604 /* 605 * Allocate a new queue entry since the received segment did not 606 * collapse onto any other out-of-order block; thus we are allocating 607 * a new block. If it had collapsed, tiqe would not be NULL and 608 * we would be reusing it. 609 * XXX If we can't, just drop the packet. XXX 610 */ 611 if (tiqe == NULL) { 612 tiqe = pool_get(&ipqent_pool, PR_NOWAIT); 613 if (tiqe == NULL) { 614 tcpstat.tcps_rcvmemdrop++; 615 m_freem(m); 616 return (0); 617 } 618 } 619 620 /* 621 * Update the counters. 622 */ 623 tcpstat.tcps_rcvoopack++; 624 tcpstat.tcps_rcvoobyte += rcvoobyte; 625 if (rcvpartdupbyte) { 626 tcpstat.tcps_rcvpartduppack++; 627 tcpstat.tcps_rcvpartdupbyte += rcvpartdupbyte; 628 } 629 630 /* 631 * Insert the new fragment queue entry into both queues. 632 */ 633 tiqe->ipqe_m = m; 634 tiqe->ipqe_seq = pkt_seq; 635 tiqe->ipqe_len = pkt_len; 636 tiqe->ipqe_flags = pkt_flags; 637 if (p == NULL) { 638 TAILQ_INSERT_HEAD(&tp->segq, tiqe, ipqe_q); 639 #ifdef TCPREASS_DEBUG 640 if (tiqe->ipqe_seq != tp->rcv_nxt) 641 printf("tcp_reass[%p]: insert %u:%u(%u) at front\n", 642 tp, pkt_seq, pkt_seq + pkt_len, pkt_len); 643 #endif 644 } else { 645 TAILQ_INSERT_AFTER(&tp->segq, p, tiqe, ipqe_q); 646 #ifdef TCPREASS_DEBUG 647 printf("tcp_reass[%p]: insert %u:%u(%u) after %u:%u(%u)\n", 648 tp, pkt_seq, pkt_seq + pkt_len, pkt_len, 649 p->ipqe_seq, p->ipqe_seq + p->ipqe_len, p->ipqe_len); 650 #endif 651 } 652 653 skip_replacement: 654 655 TAILQ_INSERT_HEAD(&tp->timeq, tiqe, ipqe_timeq); 656 657 present: 658 /* 659 * Present data to user, advancing rcv_nxt through 660 * completed sequence space. 661 */ 662 if (TCPS_HAVEESTABLISHED(tp->t_state) == 0) 663 return (0); 664 q = TAILQ_FIRST(&tp->segq); 665 if (q == NULL || q->ipqe_seq != tp->rcv_nxt) 666 return (0); 667 if (tp->t_state == TCPS_SYN_RECEIVED && q->ipqe_len) 668 return (0); 669 670 tp->rcv_nxt += q->ipqe_len; 671 pkt_flags = q->ipqe_flags & TH_FIN; 672 ND6_HINT(tp); 673 674 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 675 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 676 if (so->so_state & SS_CANTRCVMORE) 677 m_freem(q->ipqe_m); 678 else 679 sbappendstream(&so->so_rcv, q->ipqe_m); 680 pool_put(&ipqent_pool, q); 681 sorwakeup(so); 682 return (pkt_flags); 683 } 684 685 #ifdef INET6 686 int 687 tcp6_input(mp, offp, proto) 688 struct mbuf **mp; 689 int *offp, proto; 690 { 691 struct mbuf *m = *mp; 692 693 /* 694 * draft-itojun-ipv6-tcp-to-anycast 695 * better place to put this in? 696 */ 697 if (m->m_flags & M_ANYCAST6) { 698 struct ip6_hdr *ip6; 699 if (m->m_len < sizeof(struct ip6_hdr)) { 700 if ((m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) { 701 tcpstat.tcps_rcvshort++; 702 return IPPROTO_DONE; 703 } 704 } 705 ip6 = mtod(m, struct ip6_hdr *); 706 icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR, 707 (caddr_t)&ip6->ip6_dst - (caddr_t)ip6); 708 return IPPROTO_DONE; 709 } 710 711 tcp_input(m, *offp, proto); 712 return IPPROTO_DONE; 713 } 714 #endif 715 716 #ifdef INET 717 static void 718 tcp4_log_refused(ip, th) 719 const struct ip *ip; 720 const struct tcphdr *th; 721 { 722 char src[4*sizeof "123"]; 723 char dst[4*sizeof "123"]; 724 725 if (ip) { 726 strlcpy(src, inet_ntoa(ip->ip_src), sizeof(src)); 727 strlcpy(dst, inet_ntoa(ip->ip_dst), sizeof(dst)); 728 } 729 else { 730 strlcpy(src, "(unknown)", sizeof(src)); 731 strlcpy(dst, "(unknown)", sizeof(dst)); 732 } 733 log(LOG_INFO, 734 "Connection attempt to TCP %s:%d from %s:%d\n", 735 dst, ntohs(th->th_dport), 736 src, ntohs(th->th_sport)); 737 } 738 #endif 739 740 #ifdef INET6 741 static void 742 tcp6_log_refused(ip6, th) 743 const struct ip6_hdr *ip6; 744 const struct tcphdr *th; 745 { 746 char src[INET6_ADDRSTRLEN]; 747 char dst[INET6_ADDRSTRLEN]; 748 749 if (ip6) { 750 strlcpy(src, ip6_sprintf(&ip6->ip6_src), sizeof(src)); 751 strlcpy(dst, ip6_sprintf(&ip6->ip6_dst), sizeof(dst)); 752 } 753 else { 754 strlcpy(src, "(unknown v6)", sizeof(src)); 755 strlcpy(dst, "(unknown v6)", sizeof(dst)); 756 } 757 log(LOG_INFO, 758 "Connection attempt to TCP [%s]:%d from [%s]:%d\n", 759 dst, ntohs(th->th_dport), 760 src, ntohs(th->th_sport)); 761 } 762 #endif 763 764 /* 765 * TCP input routine, follows pages 65-76 of the 766 * protocol specification dated September, 1981 very closely. 767 */ 768 void 769 #if __STDC__ 770 tcp_input(struct mbuf *m, ...) 771 #else 772 tcp_input(m, va_alist) 773 struct mbuf *m; 774 #endif 775 { 776 struct tcphdr *th; 777 struct ip *ip; 778 struct inpcb *inp; 779 #ifdef INET6 780 struct ip6_hdr *ip6; 781 struct in6pcb *in6p; 782 #endif 783 u_int8_t *optp = NULL; 784 int optlen = 0; 785 int len, tlen, toff, hdroptlen = 0; 786 struct tcpcb *tp = 0; 787 int tiflags; 788 struct socket *so = NULL; 789 int todrop, acked, ourfinisacked, needoutput = 0; 790 #ifdef TCP_DEBUG 791 short ostate = 0; 792 #endif 793 int iss = 0; 794 u_long tiwin; 795 struct tcp_opt_info opti; 796 int off, iphlen; 797 va_list ap; 798 int af; /* af on the wire */ 799 struct mbuf *tcp_saveti = NULL; 800 801 MCLAIM(m, &tcp_rx_mowner); 802 va_start(ap, m); 803 toff = va_arg(ap, int); 804 (void)va_arg(ap, int); /* ignore value, advance ap */ 805 va_end(ap); 806 807 tcpstat.tcps_rcvtotal++; 808 809 bzero(&opti, sizeof(opti)); 810 opti.ts_present = 0; 811 opti.maxseg = 0; 812 813 /* 814 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN. 815 * 816 * TCP is, by definition, unicast, so we reject all 817 * multicast outright. 818 * 819 * Note, there are additional src/dst address checks in 820 * the AF-specific code below. 821 */ 822 if (m->m_flags & (M_BCAST|M_MCAST)) { 823 /* XXX stat */ 824 goto drop; 825 } 826 #ifdef INET6 827 if (m->m_flags & M_ANYCAST6) { 828 /* XXX stat */ 829 goto drop; 830 } 831 #endif 832 833 /* 834 * Get IP and TCP header together in first mbuf. 835 * Note: IP leaves IP header in first mbuf. 836 */ 837 ip = mtod(m, struct ip *); 838 #ifdef INET6 839 ip6 = NULL; 840 #endif 841 switch (ip->ip_v) { 842 #ifdef INET 843 case 4: 844 af = AF_INET; 845 iphlen = sizeof(struct ip); 846 ip = mtod(m, struct ip *); 847 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, 848 sizeof(struct tcphdr)); 849 if (th == NULL) { 850 tcpstat.tcps_rcvshort++; 851 return; 852 } 853 /* We do the checksum after PCB lookup... */ 854 len = ntohs(ip->ip_len); 855 tlen = len - toff; 856 break; 857 #endif 858 #ifdef INET6 859 case 6: 860 ip = NULL; 861 iphlen = sizeof(struct ip6_hdr); 862 af = AF_INET6; 863 ip6 = mtod(m, struct ip6_hdr *); 864 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, 865 sizeof(struct tcphdr)); 866 if (th == NULL) { 867 tcpstat.tcps_rcvshort++; 868 return; 869 } 870 871 /* Be proactive about malicious use of IPv4 mapped address */ 872 if (IN6_IS_ADDR_V4MAPPED(&ip6->ip6_src) || 873 IN6_IS_ADDR_V4MAPPED(&ip6->ip6_dst)) { 874 /* XXX stat */ 875 goto drop; 876 } 877 878 /* 879 * Be proactive about unspecified IPv6 address in source. 880 * As we use all-zero to indicate unbounded/unconnected pcb, 881 * unspecified IPv6 address can be used to confuse us. 882 * 883 * Note that packets with unspecified IPv6 destination is 884 * already dropped in ip6_input. 885 */ 886 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 887 /* XXX stat */ 888 goto drop; 889 } 890 891 /* 892 * Make sure destination address is not multicast. 893 * Source address checked in ip6_input(). 894 */ 895 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) { 896 /* XXX stat */ 897 goto drop; 898 } 899 900 /* We do the checksum after PCB lookup... */ 901 len = m->m_pkthdr.len; 902 tlen = len - toff; 903 break; 904 #endif 905 default: 906 m_freem(m); 907 return; 908 } 909 910 KASSERT(TCP_HDR_ALIGNED_P(th)); 911 912 /* 913 * Check that TCP offset makes sense, 914 * pull out TCP options and adjust length. XXX 915 */ 916 off = th->th_off << 2; 917 if (off < sizeof (struct tcphdr) || off > tlen) { 918 tcpstat.tcps_rcvbadoff++; 919 goto drop; 920 } 921 tlen -= off; 922 923 /* 924 * tcp_input() has been modified to use tlen to mean the TCP data 925 * length throughout the function. Other functions can use 926 * m->m_pkthdr.len as the basis for calculating the TCP data length. 927 * rja 928 */ 929 930 if (off > sizeof (struct tcphdr)) { 931 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, off); 932 if (th == NULL) { 933 tcpstat.tcps_rcvshort++; 934 return; 935 } 936 /* 937 * NOTE: ip/ip6 will not be affected by m_pulldown() 938 * (as they're before toff) and we don't need to update those. 939 */ 940 KASSERT(TCP_HDR_ALIGNED_P(th)); 941 optlen = off - sizeof (struct tcphdr); 942 optp = ((u_int8_t *)th) + sizeof(struct tcphdr); 943 /* 944 * Do quick retrieval of timestamp options ("options 945 * prediction?"). If timestamp is the only option and it's 946 * formatted as recommended in RFC 1323 appendix A, we 947 * quickly get the values now and not bother calling 948 * tcp_dooptions(), etc. 949 */ 950 if ((optlen == TCPOLEN_TSTAMP_APPA || 951 (optlen > TCPOLEN_TSTAMP_APPA && 952 optp[TCPOLEN_TSTAMP_APPA] == TCPOPT_EOL)) && 953 *(u_int32_t *)optp == htonl(TCPOPT_TSTAMP_HDR) && 954 (th->th_flags & TH_SYN) == 0) { 955 opti.ts_present = 1; 956 opti.ts_val = ntohl(*(u_int32_t *)(optp + 4)); 957 opti.ts_ecr = ntohl(*(u_int32_t *)(optp + 8)); 958 optp = NULL; /* we've parsed the options */ 959 } 960 } 961 tiflags = th->th_flags; 962 963 /* 964 * Locate pcb for segment. 965 */ 966 findpcb: 967 inp = NULL; 968 #ifdef INET6 969 in6p = NULL; 970 #endif 971 switch (af) { 972 #ifdef INET 973 case AF_INET: 974 inp = in_pcblookup_connect(&tcbtable, ip->ip_src, th->th_sport, 975 ip->ip_dst, th->th_dport); 976 if (inp == 0) { 977 ++tcpstat.tcps_pcbhashmiss; 978 inp = in_pcblookup_bind(&tcbtable, ip->ip_dst, th->th_dport); 979 } 980 #ifdef INET6 981 if (inp == 0) { 982 struct in6_addr s, d; 983 984 /* mapped addr case */ 985 bzero(&s, sizeof(s)); 986 s.s6_addr16[5] = htons(0xffff); 987 bcopy(&ip->ip_src, &s.s6_addr32[3], sizeof(ip->ip_src)); 988 bzero(&d, sizeof(d)); 989 d.s6_addr16[5] = htons(0xffff); 990 bcopy(&ip->ip_dst, &d.s6_addr32[3], sizeof(ip->ip_dst)); 991 in6p = in6_pcblookup_connect(&tcbtable, &s, 992 th->th_sport, &d, th->th_dport, 0); 993 if (in6p == 0) { 994 ++tcpstat.tcps_pcbhashmiss; 995 in6p = in6_pcblookup_bind(&tcbtable, &d, 996 th->th_dport, 0); 997 } 998 } 999 #endif 1000 #ifndef INET6 1001 if (inp == 0) 1002 #else 1003 if (inp == 0 && in6p == 0) 1004 #endif 1005 { 1006 ++tcpstat.tcps_noport; 1007 if (tcp_log_refused && 1008 (tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) { 1009 tcp4_log_refused(ip, th); 1010 } 1011 TCP_FIELDS_TO_HOST(th); 1012 goto dropwithreset_ratelim; 1013 } 1014 #if defined(IPSEC) || defined(FAST_IPSEC) 1015 if (inp && (inp->inp_socket->so_options & SO_ACCEPTCONN) == 0 && 1016 ipsec4_in_reject(m, inp)) { 1017 ipsecstat.in_polvio++; 1018 goto drop; 1019 } 1020 #ifdef INET6 1021 else if (in6p && 1022 (in6p->in6p_socket->so_options & SO_ACCEPTCONN) == 0 && 1023 ipsec4_in_reject_so(m, in6p->in6p_socket)) { 1024 ipsecstat.in_polvio++; 1025 goto drop; 1026 } 1027 #endif 1028 #endif /*IPSEC*/ 1029 break; 1030 #endif /*INET*/ 1031 #ifdef INET6 1032 case AF_INET6: 1033 { 1034 int faith; 1035 1036 #if defined(NFAITH) && NFAITH > 0 1037 faith = faithprefix(&ip6->ip6_dst); 1038 #else 1039 faith = 0; 1040 #endif 1041 in6p = in6_pcblookup_connect(&tcbtable, &ip6->ip6_src, 1042 th->th_sport, &ip6->ip6_dst, th->th_dport, faith); 1043 if (in6p == NULL) { 1044 ++tcpstat.tcps_pcbhashmiss; 1045 in6p = in6_pcblookup_bind(&tcbtable, &ip6->ip6_dst, 1046 th->th_dport, faith); 1047 } 1048 if (in6p == NULL) { 1049 ++tcpstat.tcps_noport; 1050 if (tcp_log_refused && 1051 (tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) { 1052 tcp6_log_refused(ip6, th); 1053 } 1054 TCP_FIELDS_TO_HOST(th); 1055 goto dropwithreset_ratelim; 1056 } 1057 #if defined(IPSEC) || defined(FAST_IPSEC) 1058 if ((in6p->in6p_socket->so_options & SO_ACCEPTCONN) == 0 && 1059 ipsec6_in_reject(m, in6p)) { 1060 ipsec6stat.in_polvio++; 1061 goto drop; 1062 } 1063 #endif /*IPSEC*/ 1064 break; 1065 } 1066 #endif 1067 } 1068 1069 /* 1070 * If the state is CLOSED (i.e., TCB does not exist) then 1071 * all data in the incoming segment is discarded. 1072 * If the TCB exists but is in CLOSED state, it is embryonic, 1073 * but should either do a listen or a connect soon. 1074 */ 1075 tp = NULL; 1076 so = NULL; 1077 if (inp) { 1078 tp = intotcpcb(inp); 1079 so = inp->inp_socket; 1080 } 1081 #ifdef INET6 1082 else if (in6p) { 1083 tp = in6totcpcb(in6p); 1084 so = in6p->in6p_socket; 1085 } 1086 #endif 1087 if (tp == 0) { 1088 TCP_FIELDS_TO_HOST(th); 1089 goto dropwithreset_ratelim; 1090 } 1091 if (tp->t_state == TCPS_CLOSED) 1092 goto drop; 1093 1094 /* 1095 * Checksum extended TCP header and data. 1096 */ 1097 switch (af) { 1098 #ifdef INET 1099 case AF_INET: 1100 switch (m->m_pkthdr.csum_flags & 1101 ((m->m_pkthdr.rcvif->if_csum_flags_rx & M_CSUM_TCPv4) | 1102 M_CSUM_TCP_UDP_BAD | M_CSUM_DATA)) { 1103 case M_CSUM_TCPv4|M_CSUM_TCP_UDP_BAD: 1104 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_bad); 1105 goto badcsum; 1106 1107 case M_CSUM_TCPv4|M_CSUM_DATA: { 1108 u_int32_t hw_csum = m->m_pkthdr.csum_data; 1109 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_data); 1110 if (m->m_pkthdr.csum_flags & M_CSUM_NO_PSEUDOHDR) { 1111 hw_csum = in_cksum_phdr(ip->ip_src.s_addr, 1112 ip->ip_dst.s_addr, 1113 htonl(hw_csum + ntohs(ip->ip_len) + 1114 IPPROTO_UDP)); 1115 } 1116 if ((hw_csum ^ 0xffff) != 0) 1117 goto badcsum; 1118 break; 1119 } 1120 1121 case M_CSUM_TCPv4: 1122 /* Checksum was okay. */ 1123 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_ok); 1124 break; 1125 1126 default: 1127 /* Must compute it ourselves. */ 1128 TCP_CSUM_COUNTER_INCR(&tcp_swcsum); 1129 if (in4_cksum(m, IPPROTO_TCP, toff, tlen + off) != 0) 1130 goto badcsum; 1131 break; 1132 } 1133 break; 1134 #endif /* INET4 */ 1135 1136 #ifdef INET6 1137 case AF_INET6: 1138 if (in6_cksum(m, IPPROTO_TCP, toff, tlen + off) != 0) 1139 goto badcsum; 1140 break; 1141 #endif /* INET6 */ 1142 } 1143 1144 TCP_FIELDS_TO_HOST(th); 1145 1146 /* Unscale the window into a 32-bit value. */ 1147 if ((tiflags & TH_SYN) == 0) 1148 tiwin = th->th_win << tp->snd_scale; 1149 else 1150 tiwin = th->th_win; 1151 1152 #ifdef INET6 1153 /* save packet options if user wanted */ 1154 if (in6p && (in6p->in6p_flags & IN6P_CONTROLOPTS)) { 1155 if (in6p->in6p_options) { 1156 m_freem(in6p->in6p_options); 1157 in6p->in6p_options = 0; 1158 } 1159 ip6_savecontrol(in6p, &in6p->in6p_options, ip6, m); 1160 } 1161 #endif 1162 1163 if (so->so_options & (SO_DEBUG|SO_ACCEPTCONN)) { 1164 union syn_cache_sa src; 1165 union syn_cache_sa dst; 1166 1167 bzero(&src, sizeof(src)); 1168 bzero(&dst, sizeof(dst)); 1169 switch (af) { 1170 #ifdef INET 1171 case AF_INET: 1172 src.sin.sin_len = sizeof(struct sockaddr_in); 1173 src.sin.sin_family = AF_INET; 1174 src.sin.sin_addr = ip->ip_src; 1175 src.sin.sin_port = th->th_sport; 1176 1177 dst.sin.sin_len = sizeof(struct sockaddr_in); 1178 dst.sin.sin_family = AF_INET; 1179 dst.sin.sin_addr = ip->ip_dst; 1180 dst.sin.sin_port = th->th_dport; 1181 break; 1182 #endif 1183 #ifdef INET6 1184 case AF_INET6: 1185 src.sin6.sin6_len = sizeof(struct sockaddr_in6); 1186 src.sin6.sin6_family = AF_INET6; 1187 src.sin6.sin6_addr = ip6->ip6_src; 1188 src.sin6.sin6_port = th->th_sport; 1189 1190 dst.sin6.sin6_len = sizeof(struct sockaddr_in6); 1191 dst.sin6.sin6_family = AF_INET6; 1192 dst.sin6.sin6_addr = ip6->ip6_dst; 1193 dst.sin6.sin6_port = th->th_dport; 1194 break; 1195 #endif /* INET6 */ 1196 default: 1197 goto badsyn; /*sanity*/ 1198 } 1199 1200 if (so->so_options & SO_DEBUG) { 1201 #ifdef TCP_DEBUG 1202 ostate = tp->t_state; 1203 #endif 1204 1205 tcp_saveti = NULL; 1206 if (iphlen + sizeof(struct tcphdr) > MHLEN) 1207 goto nosave; 1208 1209 if (m->m_len > iphlen && (m->m_flags & M_EXT) == 0) { 1210 tcp_saveti = m_copym(m, 0, iphlen, M_DONTWAIT); 1211 if (!tcp_saveti) 1212 goto nosave; 1213 } else { 1214 MGETHDR(tcp_saveti, M_DONTWAIT, MT_HEADER); 1215 if (!tcp_saveti) 1216 goto nosave; 1217 MCLAIM(m, &tcp_mowner); 1218 tcp_saveti->m_len = iphlen; 1219 m_copydata(m, 0, iphlen, 1220 mtod(tcp_saveti, caddr_t)); 1221 } 1222 1223 if (M_TRAILINGSPACE(tcp_saveti) < sizeof(struct tcphdr)) { 1224 m_freem(tcp_saveti); 1225 tcp_saveti = NULL; 1226 } else { 1227 tcp_saveti->m_len += sizeof(struct tcphdr); 1228 bcopy(th, mtod(tcp_saveti, caddr_t) + iphlen, 1229 sizeof(struct tcphdr)); 1230 } 1231 nosave:; 1232 } 1233 if (so->so_options & SO_ACCEPTCONN) { 1234 if ((tiflags & (TH_RST|TH_ACK|TH_SYN)) != TH_SYN) { 1235 if (tiflags & TH_RST) { 1236 syn_cache_reset(&src.sa, &dst.sa, th); 1237 } else if ((tiflags & (TH_ACK|TH_SYN)) == 1238 (TH_ACK|TH_SYN)) { 1239 /* 1240 * Received a SYN,ACK. This should 1241 * never happen while we are in 1242 * LISTEN. Send an RST. 1243 */ 1244 goto badsyn; 1245 } else if (tiflags & TH_ACK) { 1246 so = syn_cache_get(&src.sa, &dst.sa, 1247 th, toff, tlen, so, m); 1248 if (so == NULL) { 1249 /* 1250 * We don't have a SYN for 1251 * this ACK; send an RST. 1252 */ 1253 goto badsyn; 1254 } else if (so == 1255 (struct socket *)(-1)) { 1256 /* 1257 * We were unable to create 1258 * the connection. If the 1259 * 3-way handshake was 1260 * completed, and RST has 1261 * been sent to the peer. 1262 * Since the mbuf might be 1263 * in use for the reply, 1264 * do not free it. 1265 */ 1266 m = NULL; 1267 } else { 1268 /* 1269 * We have created a 1270 * full-blown connection. 1271 */ 1272 tp = NULL; 1273 inp = NULL; 1274 #ifdef INET6 1275 in6p = NULL; 1276 #endif 1277 switch (so->so_proto->pr_domain->dom_family) { 1278 #ifdef INET 1279 case AF_INET: 1280 inp = sotoinpcb(so); 1281 tp = intotcpcb(inp); 1282 break; 1283 #endif 1284 #ifdef INET6 1285 case AF_INET6: 1286 in6p = sotoin6pcb(so); 1287 tp = in6totcpcb(in6p); 1288 break; 1289 #endif 1290 } 1291 if (tp == NULL) 1292 goto badsyn; /*XXX*/ 1293 tiwin <<= tp->snd_scale; 1294 goto after_listen; 1295 } 1296 } else { 1297 /* 1298 * None of RST, SYN or ACK was set. 1299 * This is an invalid packet for a 1300 * TCB in LISTEN state. Send a RST. 1301 */ 1302 goto badsyn; 1303 } 1304 } else { 1305 /* 1306 * Received a SYN. 1307 */ 1308 1309 #ifdef INET6 1310 /* 1311 * If deprecated address is forbidden, we do 1312 * not accept SYN to deprecated interface 1313 * address to prevent any new inbound 1314 * connection from getting established. 1315 * When we do not accept SYN, we send a TCP 1316 * RST, with deprecated source address (instead 1317 * of dropping it). We compromise it as it is 1318 * much better for peer to send a RST, and 1319 * RST will be the final packet for the 1320 * exchange. 1321 * 1322 * If we do not forbid deprecated addresses, we 1323 * accept the SYN packet. RFC2462 does not 1324 * suggest dropping SYN in this case. 1325 * If we decipher RFC2462 5.5.4, it says like 1326 * this: 1327 * 1. use of deprecated addr with existing 1328 * communication is okay - "SHOULD continue 1329 * to be used" 1330 * 2. use of it with new communication: 1331 * (2a) "SHOULD NOT be used if alternate 1332 * address with sufficient scope is 1333 * available" 1334 * (2b) nothing mentioned otherwise. 1335 * Here we fall into (2b) case as we have no 1336 * choice in our source address selection - we 1337 * must obey the peer. 1338 * 1339 * The wording in RFC2462 is confusing, and 1340 * there are multiple description text for 1341 * deprecated address handling - worse, they 1342 * are not exactly the same. I believe 5.5.4 1343 * is the best one, so we follow 5.5.4. 1344 */ 1345 if (af == AF_INET6 && !ip6_use_deprecated) { 1346 struct in6_ifaddr *ia6; 1347 if ((ia6 = in6ifa_ifpwithaddr(m->m_pkthdr.rcvif, 1348 &ip6->ip6_dst)) && 1349 (ia6->ia6_flags & IN6_IFF_DEPRECATED)) { 1350 tp = NULL; 1351 goto dropwithreset; 1352 } 1353 } 1354 #endif 1355 1356 #ifdef IPSEC 1357 switch (af) { 1358 case AF_INET: 1359 if (ipsec4_in_reject_so(m, so)) { 1360 ipsecstat.in_polvio++; 1361 tp = NULL; 1362 goto dropwithreset; 1363 } 1364 break; 1365 #ifdef INET6 1366 case AF_INET6: 1367 if (ipsec6_in_reject_so(m, so)) { 1368 ipsec6stat.in_polvio++; 1369 tp = NULL; 1370 goto dropwithreset; 1371 } 1372 break; 1373 #endif 1374 } 1375 #endif 1376 1377 /* 1378 * LISTEN socket received a SYN 1379 * from itself? This can't possibly 1380 * be valid; drop the packet. 1381 */ 1382 if (th->th_sport == th->th_dport) { 1383 int i; 1384 1385 switch (af) { 1386 #ifdef INET 1387 case AF_INET: 1388 i = in_hosteq(ip->ip_src, ip->ip_dst); 1389 break; 1390 #endif 1391 #ifdef INET6 1392 case AF_INET6: 1393 i = IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &ip6->ip6_dst); 1394 break; 1395 #endif 1396 default: 1397 i = 1; 1398 } 1399 if (i) { 1400 tcpstat.tcps_badsyn++; 1401 goto drop; 1402 } 1403 } 1404 1405 /* 1406 * SYN looks ok; create compressed TCP 1407 * state for it. 1408 */ 1409 if (so->so_qlen <= so->so_qlimit && 1410 syn_cache_add(&src.sa, &dst.sa, th, tlen, 1411 so, m, optp, optlen, &opti)) 1412 m = NULL; 1413 } 1414 goto drop; 1415 } 1416 } 1417 1418 after_listen: 1419 #ifdef DIAGNOSTIC 1420 /* 1421 * Should not happen now that all embryonic connections 1422 * are handled with compressed state. 1423 */ 1424 if (tp->t_state == TCPS_LISTEN) 1425 panic("tcp_input: TCPS_LISTEN"); 1426 #endif 1427 1428 /* 1429 * Segment received on connection. 1430 * Reset idle time and keep-alive timer. 1431 */ 1432 tp->t_rcvtime = tcp_now; 1433 if (TCPS_HAVEESTABLISHED(tp->t_state)) 1434 TCP_TIMER_ARM(tp, TCPT_KEEP, tcp_keepidle); 1435 1436 /* 1437 * Process options. 1438 */ 1439 if (optp) 1440 tcp_dooptions(tp, optp, optlen, th, &opti); 1441 1442 /* 1443 * Header prediction: check for the two common cases 1444 * of a uni-directional data xfer. If the packet has 1445 * no control flags, is in-sequence, the window didn't 1446 * change and we're not retransmitting, it's a 1447 * candidate. If the length is zero and the ack moved 1448 * forward, we're the sender side of the xfer. Just 1449 * free the data acked & wake any higher level process 1450 * that was blocked waiting for space. If the length 1451 * is non-zero and the ack didn't move, we're the 1452 * receiver side. If we're getting packets in-order 1453 * (the reassembly queue is empty), add the data to 1454 * the socket buffer and note that we need a delayed ack. 1455 */ 1456 if (tp->t_state == TCPS_ESTABLISHED && 1457 (tiflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK && 1458 (!opti.ts_present || TSTMP_GEQ(opti.ts_val, tp->ts_recent)) && 1459 th->th_seq == tp->rcv_nxt && 1460 tiwin && tiwin == tp->snd_wnd && 1461 tp->snd_nxt == tp->snd_max) { 1462 1463 /* 1464 * If last ACK falls within this segment's sequence numbers, 1465 * record the timestamp. 1466 */ 1467 if (opti.ts_present && 1468 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 1469 SEQ_LT(tp->last_ack_sent, th->th_seq + tlen)) { 1470 tp->ts_recent_age = TCP_TIMESTAMP(tp); 1471 tp->ts_recent = opti.ts_val; 1472 } 1473 1474 if (tlen == 0) { 1475 if (SEQ_GT(th->th_ack, tp->snd_una) && 1476 SEQ_LEQ(th->th_ack, tp->snd_max) && 1477 tp->snd_cwnd >= tp->snd_wnd && 1478 tp->t_dupacks < tcprexmtthresh) { 1479 /* 1480 * this is a pure ack for outstanding data. 1481 */ 1482 ++tcpstat.tcps_predack; 1483 if (opti.ts_present && opti.ts_ecr) 1484 tcp_xmit_timer(tp, 1485 TCP_TIMESTAMP(tp) - opti.ts_ecr + 1); 1486 else if (tp->t_rtttime && 1487 SEQ_GT(th->th_ack, tp->t_rtseq)) 1488 tcp_xmit_timer(tp, 1489 tcp_now - tp->t_rtttime); 1490 acked = th->th_ack - tp->snd_una; 1491 tcpstat.tcps_rcvackpack++; 1492 tcpstat.tcps_rcvackbyte += acked; 1493 ND6_HINT(tp); 1494 1495 if (acked > (tp->t_lastoff - tp->t_inoff)) 1496 tp->t_lastm = NULL; 1497 sbdrop(&so->so_snd, acked); 1498 tp->t_lastoff -= acked; 1499 1500 /* 1501 * We want snd_recover to track snd_una to 1502 * avoid sequence wraparound problems for 1503 * very large transfers. 1504 */ 1505 tp->snd_una = tp->snd_recover = th->th_ack; 1506 m_freem(m); 1507 1508 /* 1509 * If all outstanding data are acked, stop 1510 * retransmit timer, otherwise restart timer 1511 * using current (possibly backed-off) value. 1512 * If process is waiting for space, 1513 * wakeup/selwakeup/signal. If data 1514 * are ready to send, let tcp_output 1515 * decide between more output or persist. 1516 */ 1517 if (tp->snd_una == tp->snd_max) 1518 TCP_TIMER_DISARM(tp, TCPT_REXMT); 1519 else if (TCP_TIMER_ISARMED(tp, 1520 TCPT_PERSIST) == 0) 1521 TCP_TIMER_ARM(tp, TCPT_REXMT, 1522 tp->t_rxtcur); 1523 1524 sowwakeup(so); 1525 if (so->so_snd.sb_cc) 1526 (void) tcp_output(tp); 1527 if (tcp_saveti) 1528 m_freem(tcp_saveti); 1529 return; 1530 } 1531 } else if (th->th_ack == tp->snd_una && 1532 TAILQ_FIRST(&tp->segq) == NULL && 1533 tlen <= sbspace(&so->so_rcv)) { 1534 /* 1535 * this is a pure, in-sequence data packet 1536 * with nothing on the reassembly queue and 1537 * we have enough buffer space to take it. 1538 */ 1539 ++tcpstat.tcps_preddat; 1540 tp->rcv_nxt += tlen; 1541 tcpstat.tcps_rcvpack++; 1542 tcpstat.tcps_rcvbyte += tlen; 1543 ND6_HINT(tp); 1544 /* 1545 * Drop TCP, IP headers and TCP options then add data 1546 * to socket buffer. 1547 */ 1548 if (so->so_state & SS_CANTRCVMORE) 1549 m_freem(m); 1550 else { 1551 m_adj(m, toff + off); 1552 sbappendstream(&so->so_rcv, m); 1553 } 1554 sorwakeup(so); 1555 TCP_SETUP_ACK(tp, th); 1556 if (tp->t_flags & TF_ACKNOW) 1557 (void) tcp_output(tp); 1558 if (tcp_saveti) 1559 m_freem(tcp_saveti); 1560 return; 1561 } 1562 } 1563 1564 /* 1565 * Compute mbuf offset to TCP data segment. 1566 */ 1567 hdroptlen = toff + off; 1568 1569 /* 1570 * Calculate amount of space in receive window, 1571 * and then do TCP input processing. 1572 * Receive window is amount of space in rcv queue, 1573 * but not less than advertised window. 1574 */ 1575 { int win; 1576 1577 win = sbspace(&so->so_rcv); 1578 if (win < 0) 1579 win = 0; 1580 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 1581 } 1582 1583 switch (tp->t_state) { 1584 case TCPS_LISTEN: 1585 /* 1586 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN 1587 */ 1588 if (m->m_flags & (M_BCAST|M_MCAST)) 1589 goto drop; 1590 switch (af) { 1591 #ifdef INET6 1592 case AF_INET6: 1593 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) 1594 goto drop; 1595 break; 1596 #endif /* INET6 */ 1597 case AF_INET: 1598 if (IN_MULTICAST(ip->ip_dst.s_addr) || 1599 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 1600 goto drop; 1601 break; 1602 } 1603 break; 1604 1605 /* 1606 * If the state is SYN_SENT: 1607 * if seg contains an ACK, but not for our SYN, drop the input. 1608 * if seg contains a RST, then drop the connection. 1609 * if seg does not contain SYN, then drop it. 1610 * Otherwise this is an acceptable SYN segment 1611 * initialize tp->rcv_nxt and tp->irs 1612 * if seg contains ack then advance tp->snd_una 1613 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 1614 * arrange for segment to be acked (eventually) 1615 * continue processing rest of data/controls, beginning with URG 1616 */ 1617 case TCPS_SYN_SENT: 1618 if ((tiflags & TH_ACK) && 1619 (SEQ_LEQ(th->th_ack, tp->iss) || 1620 SEQ_GT(th->th_ack, tp->snd_max))) 1621 goto dropwithreset; 1622 if (tiflags & TH_RST) { 1623 if (tiflags & TH_ACK) 1624 tp = tcp_drop(tp, ECONNREFUSED); 1625 goto drop; 1626 } 1627 if ((tiflags & TH_SYN) == 0) 1628 goto drop; 1629 if (tiflags & TH_ACK) { 1630 tp->snd_una = tp->snd_recover = th->th_ack; 1631 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 1632 tp->snd_nxt = tp->snd_una; 1633 TCP_TIMER_DISARM(tp, TCPT_REXMT); 1634 } 1635 tp->irs = th->th_seq; 1636 tcp_rcvseqinit(tp); 1637 tp->t_flags |= TF_ACKNOW; 1638 tcp_mss_from_peer(tp, opti.maxseg); 1639 1640 /* 1641 * Initialize the initial congestion window. If we 1642 * had to retransmit the SYN, we must initialize cwnd 1643 * to 1 segment (i.e. the Loss Window). 1644 */ 1645 if (tp->t_flags & TF_SYN_REXMT) 1646 tp->snd_cwnd = tp->t_peermss; 1647 else { 1648 int ss = tcp_init_win; 1649 #ifdef INET 1650 if (inp != NULL && in_localaddr(inp->inp_faddr)) 1651 ss = tcp_init_win_local; 1652 #endif 1653 #ifdef INET6 1654 if (in6p != NULL && in6_localaddr(&in6p->in6p_faddr)) 1655 ss = tcp_init_win_local; 1656 #endif 1657 tp->snd_cwnd = TCP_INITIAL_WINDOW(ss, tp->t_peermss); 1658 } 1659 1660 tcp_rmx_rtt(tp); 1661 if (tiflags & TH_ACK) { 1662 tcpstat.tcps_connects++; 1663 soisconnected(so); 1664 tcp_established(tp); 1665 /* Do window scaling on this connection? */ 1666 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 1667 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 1668 tp->snd_scale = tp->requested_s_scale; 1669 tp->rcv_scale = tp->request_r_scale; 1670 } 1671 TCP_REASS_LOCK(tp); 1672 (void) tcp_reass(tp, NULL, (struct mbuf *)0, &tlen); 1673 TCP_REASS_UNLOCK(tp); 1674 /* 1675 * if we didn't have to retransmit the SYN, 1676 * use its rtt as our initial srtt & rtt var. 1677 */ 1678 if (tp->t_rtttime) 1679 tcp_xmit_timer(tp, tcp_now - tp->t_rtttime); 1680 } else 1681 tp->t_state = TCPS_SYN_RECEIVED; 1682 1683 /* 1684 * Advance th->th_seq to correspond to first data byte. 1685 * If data, trim to stay within window, 1686 * dropping FIN if necessary. 1687 */ 1688 th->th_seq++; 1689 if (tlen > tp->rcv_wnd) { 1690 todrop = tlen - tp->rcv_wnd; 1691 m_adj(m, -todrop); 1692 tlen = tp->rcv_wnd; 1693 tiflags &= ~TH_FIN; 1694 tcpstat.tcps_rcvpackafterwin++; 1695 tcpstat.tcps_rcvbyteafterwin += todrop; 1696 } 1697 tp->snd_wl1 = th->th_seq - 1; 1698 tp->rcv_up = th->th_seq; 1699 goto step6; 1700 1701 /* 1702 * If the state is SYN_RECEIVED: 1703 * If seg contains an ACK, but not for our SYN, drop the input 1704 * and generate an RST. See page 36, rfc793 1705 */ 1706 case TCPS_SYN_RECEIVED: 1707 if ((tiflags & TH_ACK) && 1708 (SEQ_LEQ(th->th_ack, tp->iss) || 1709 SEQ_GT(th->th_ack, tp->snd_max))) 1710 goto dropwithreset; 1711 break; 1712 } 1713 1714 /* 1715 * States other than LISTEN or SYN_SENT. 1716 * First check timestamp, if present. 1717 * Then check that at least some bytes of segment are within 1718 * receive window. If segment begins before rcv_nxt, 1719 * drop leading data (and SYN); if nothing left, just ack. 1720 * 1721 * RFC 1323 PAWS: If we have a timestamp reply on this segment 1722 * and it's less than ts_recent, drop it. 1723 */ 1724 if (opti.ts_present && (tiflags & TH_RST) == 0 && tp->ts_recent && 1725 TSTMP_LT(opti.ts_val, tp->ts_recent)) { 1726 1727 /* Check to see if ts_recent is over 24 days old. */ 1728 if ((int)(TCP_TIMESTAMP(tp) - tp->ts_recent_age) > 1729 TCP_PAWS_IDLE) { 1730 /* 1731 * Invalidate ts_recent. If this segment updates 1732 * ts_recent, the age will be reset later and ts_recent 1733 * will get a valid value. If it does not, setting 1734 * ts_recent to zero will at least satisfy the 1735 * requirement that zero be placed in the timestamp 1736 * echo reply when ts_recent isn't valid. The 1737 * age isn't reset until we get a valid ts_recent 1738 * because we don't want out-of-order segments to be 1739 * dropped when ts_recent is old. 1740 */ 1741 tp->ts_recent = 0; 1742 } else { 1743 tcpstat.tcps_rcvduppack++; 1744 tcpstat.tcps_rcvdupbyte += tlen; 1745 tcpstat.tcps_pawsdrop++; 1746 goto dropafterack; 1747 } 1748 } 1749 1750 todrop = tp->rcv_nxt - th->th_seq; 1751 if (todrop > 0) { 1752 if (tiflags & TH_SYN) { 1753 tiflags &= ~TH_SYN; 1754 th->th_seq++; 1755 if (th->th_urp > 1) 1756 th->th_urp--; 1757 else { 1758 tiflags &= ~TH_URG; 1759 th->th_urp = 0; 1760 } 1761 todrop--; 1762 } 1763 if (todrop > tlen || 1764 (todrop == tlen && (tiflags & TH_FIN) == 0)) { 1765 /* 1766 * Any valid FIN must be to the left of the window. 1767 * At this point the FIN must be a duplicate or 1768 * out of sequence; drop it. 1769 */ 1770 tiflags &= ~TH_FIN; 1771 /* 1772 * Send an ACK to resynchronize and drop any data. 1773 * But keep on processing for RST or ACK. 1774 */ 1775 tp->t_flags |= TF_ACKNOW; 1776 todrop = tlen; 1777 tcpstat.tcps_rcvdupbyte += todrop; 1778 tcpstat.tcps_rcvduppack++; 1779 } else { 1780 tcpstat.tcps_rcvpartduppack++; 1781 tcpstat.tcps_rcvpartdupbyte += todrop; 1782 } 1783 hdroptlen += todrop; /*drop from head afterwards*/ 1784 th->th_seq += todrop; 1785 tlen -= todrop; 1786 if (th->th_urp > todrop) 1787 th->th_urp -= todrop; 1788 else { 1789 tiflags &= ~TH_URG; 1790 th->th_urp = 0; 1791 } 1792 } 1793 1794 /* 1795 * If new data are received on a connection after the 1796 * user processes are gone, then RST the other end. 1797 */ 1798 if ((so->so_state & SS_NOFDREF) && 1799 tp->t_state > TCPS_CLOSE_WAIT && tlen) { 1800 tp = tcp_close(tp); 1801 tcpstat.tcps_rcvafterclose++; 1802 goto dropwithreset; 1803 } 1804 1805 /* 1806 * If segment ends after window, drop trailing data 1807 * (and PUSH and FIN); if nothing left, just ACK. 1808 */ 1809 todrop = (th->th_seq + tlen) - (tp->rcv_nxt+tp->rcv_wnd); 1810 if (todrop > 0) { 1811 tcpstat.tcps_rcvpackafterwin++; 1812 if (todrop >= tlen) { 1813 tcpstat.tcps_rcvbyteafterwin += tlen; 1814 /* 1815 * If a new connection request is received 1816 * while in TIME_WAIT, drop the old connection 1817 * and start over if the sequence numbers 1818 * are above the previous ones. 1819 * 1820 * NOTE: We will checksum the packet again, and 1821 * so we need to put the header fields back into 1822 * network order! 1823 * XXX This kind of sucks, but we don't expect 1824 * XXX this to happen very often, so maybe it 1825 * XXX doesn't matter so much. 1826 */ 1827 if (tiflags & TH_SYN && 1828 tp->t_state == TCPS_TIME_WAIT && 1829 SEQ_GT(th->th_seq, tp->rcv_nxt)) { 1830 iss = tcp_new_iss(tp, tp->snd_nxt); 1831 tp = tcp_close(tp); 1832 TCP_FIELDS_TO_NET(th); 1833 goto findpcb; 1834 } 1835 /* 1836 * If window is closed can only take segments at 1837 * window edge, and have to drop data and PUSH from 1838 * incoming segments. Continue processing, but 1839 * remember to ack. Otherwise, drop segment 1840 * and ack. 1841 */ 1842 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 1843 tp->t_flags |= TF_ACKNOW; 1844 tcpstat.tcps_rcvwinprobe++; 1845 } else 1846 goto dropafterack; 1847 } else 1848 tcpstat.tcps_rcvbyteafterwin += todrop; 1849 m_adj(m, -todrop); 1850 tlen -= todrop; 1851 tiflags &= ~(TH_PUSH|TH_FIN); 1852 } 1853 1854 /* 1855 * If last ACK falls within this segment's sequence numbers, 1856 * and the timestamp is newer, record it. 1857 */ 1858 if (opti.ts_present && TSTMP_GEQ(opti.ts_val, tp->ts_recent) && 1859 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 1860 SEQ_LT(tp->last_ack_sent, th->th_seq + tlen + 1861 ((tiflags & (TH_SYN|TH_FIN)) != 0))) { 1862 tp->ts_recent_age = TCP_TIMESTAMP(tp); 1863 tp->ts_recent = opti.ts_val; 1864 } 1865 1866 /* 1867 * If the RST bit is set examine the state: 1868 * SYN_RECEIVED STATE: 1869 * If passive open, return to LISTEN state. 1870 * If active open, inform user that connection was refused. 1871 * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES: 1872 * Inform user that connection was reset, and close tcb. 1873 * CLOSING, LAST_ACK, TIME_WAIT STATES 1874 * Close the tcb. 1875 */ 1876 if (tiflags&TH_RST) switch (tp->t_state) { 1877 1878 case TCPS_SYN_RECEIVED: 1879 so->so_error = ECONNREFUSED; 1880 goto close; 1881 1882 case TCPS_ESTABLISHED: 1883 case TCPS_FIN_WAIT_1: 1884 case TCPS_FIN_WAIT_2: 1885 case TCPS_CLOSE_WAIT: 1886 so->so_error = ECONNRESET; 1887 close: 1888 tp->t_state = TCPS_CLOSED; 1889 tcpstat.tcps_drops++; 1890 tp = tcp_close(tp); 1891 goto drop; 1892 1893 case TCPS_CLOSING: 1894 case TCPS_LAST_ACK: 1895 case TCPS_TIME_WAIT: 1896 tp = tcp_close(tp); 1897 goto drop; 1898 } 1899 1900 /* 1901 * If a SYN is in the window, then this is an 1902 * error and we send an RST and drop the connection. 1903 */ 1904 if (tiflags & TH_SYN) { 1905 tp = tcp_drop(tp, ECONNRESET); 1906 goto dropwithreset; 1907 } 1908 1909 /* 1910 * If the ACK bit is off we drop the segment and return. 1911 */ 1912 if ((tiflags & TH_ACK) == 0) { 1913 if (tp->t_flags & TF_ACKNOW) 1914 goto dropafterack; 1915 else 1916 goto drop; 1917 } 1918 1919 /* 1920 * Ack processing. 1921 */ 1922 switch (tp->t_state) { 1923 1924 /* 1925 * In SYN_RECEIVED state if the ack ACKs our SYN then enter 1926 * ESTABLISHED state and continue processing, otherwise 1927 * send an RST. 1928 */ 1929 case TCPS_SYN_RECEIVED: 1930 if (SEQ_GT(tp->snd_una, th->th_ack) || 1931 SEQ_GT(th->th_ack, tp->snd_max)) 1932 goto dropwithreset; 1933 tcpstat.tcps_connects++; 1934 soisconnected(so); 1935 tcp_established(tp); 1936 /* Do window scaling? */ 1937 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 1938 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 1939 tp->snd_scale = tp->requested_s_scale; 1940 tp->rcv_scale = tp->request_r_scale; 1941 } 1942 TCP_REASS_LOCK(tp); 1943 (void) tcp_reass(tp, NULL, (struct mbuf *)0, &tlen); 1944 TCP_REASS_UNLOCK(tp); 1945 tp->snd_wl1 = th->th_seq - 1; 1946 /* fall into ... */ 1947 1948 /* 1949 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 1950 * ACKs. If the ack is in the range 1951 * tp->snd_una < th->th_ack <= tp->snd_max 1952 * then advance tp->snd_una to th->th_ack and drop 1953 * data from the retransmission queue. If this ACK reflects 1954 * more up to date window information we update our window information. 1955 */ 1956 case TCPS_ESTABLISHED: 1957 case TCPS_FIN_WAIT_1: 1958 case TCPS_FIN_WAIT_2: 1959 case TCPS_CLOSE_WAIT: 1960 case TCPS_CLOSING: 1961 case TCPS_LAST_ACK: 1962 case TCPS_TIME_WAIT: 1963 1964 if (SEQ_LEQ(th->th_ack, tp->snd_una)) { 1965 if (tlen == 0 && tiwin == tp->snd_wnd) { 1966 tcpstat.tcps_rcvdupack++; 1967 /* 1968 * If we have outstanding data (other than 1969 * a window probe), this is a completely 1970 * duplicate ack (ie, window info didn't 1971 * change), the ack is the biggest we've 1972 * seen and we've seen exactly our rexmt 1973 * threshhold of them, assume a packet 1974 * has been dropped and retransmit it. 1975 * Kludge snd_nxt & the congestion 1976 * window so we send only this one 1977 * packet. 1978 * 1979 * We know we're losing at the current 1980 * window size so do congestion avoidance 1981 * (set ssthresh to half the current window 1982 * and pull our congestion window back to 1983 * the new ssthresh). 1984 * 1985 * Dup acks mean that packets have left the 1986 * network (they're now cached at the receiver) 1987 * so bump cwnd by the amount in the receiver 1988 * to keep a constant cwnd packets in the 1989 * network. 1990 */ 1991 if (TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 || 1992 th->th_ack != tp->snd_una) 1993 tp->t_dupacks = 0; 1994 else if (++tp->t_dupacks == tcprexmtthresh) { 1995 tcp_seq onxt = tp->snd_nxt; 1996 u_int win = 1997 min(tp->snd_wnd, tp->snd_cwnd) / 1998 2 / tp->t_segsz; 1999 if (tcp_do_newreno && SEQ_LT(th->th_ack, 2000 tp->snd_recover)) { 2001 /* 2002 * False fast retransmit after 2003 * timeout. Do not cut window. 2004 */ 2005 tp->snd_cwnd += tp->t_segsz; 2006 tp->t_dupacks = 0; 2007 (void) tcp_output(tp); 2008 goto drop; 2009 } 2010 2011 if (win < 2) 2012 win = 2; 2013 tp->snd_ssthresh = win * tp->t_segsz; 2014 tp->snd_recover = tp->snd_max; 2015 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2016 tp->t_rtttime = 0; 2017 tp->snd_nxt = th->th_ack; 2018 tp->snd_cwnd = tp->t_segsz; 2019 (void) tcp_output(tp); 2020 tp->snd_cwnd = tp->snd_ssthresh + 2021 tp->t_segsz * tp->t_dupacks; 2022 if (SEQ_GT(onxt, tp->snd_nxt)) 2023 tp->snd_nxt = onxt; 2024 goto drop; 2025 } else if (tp->t_dupacks > tcprexmtthresh) { 2026 tp->snd_cwnd += tp->t_segsz; 2027 (void) tcp_output(tp); 2028 goto drop; 2029 } 2030 } else 2031 tp->t_dupacks = 0; 2032 break; 2033 } 2034 /* 2035 * If the congestion window was inflated to account 2036 * for the other side's cached packets, retract it. 2037 */ 2038 if (tcp_do_newreno == 0) { 2039 if (tp->t_dupacks >= tcprexmtthresh && 2040 tp->snd_cwnd > tp->snd_ssthresh) 2041 tp->snd_cwnd = tp->snd_ssthresh; 2042 tp->t_dupacks = 0; 2043 } else if (tp->t_dupacks >= tcprexmtthresh && 2044 tcp_newreno(tp, th) == 0) { 2045 tp->snd_cwnd = tp->snd_ssthresh; 2046 /* 2047 * Window inflation should have left us with approx. 2048 * snd_ssthresh outstanding data. But in case we 2049 * would be inclined to send a burst, better to do 2050 * it via the slow start mechanism. 2051 */ 2052 if (SEQ_SUB(tp->snd_max, th->th_ack) < tp->snd_ssthresh) 2053 tp->snd_cwnd = SEQ_SUB(tp->snd_max, th->th_ack) 2054 + tp->t_segsz; 2055 tp->t_dupacks = 0; 2056 } 2057 if (SEQ_GT(th->th_ack, tp->snd_max)) { 2058 tcpstat.tcps_rcvacktoomuch++; 2059 goto dropafterack; 2060 } 2061 acked = th->th_ack - tp->snd_una; 2062 tcpstat.tcps_rcvackpack++; 2063 tcpstat.tcps_rcvackbyte += acked; 2064 2065 /* 2066 * If we have a timestamp reply, update smoothed 2067 * round trip time. If no timestamp is present but 2068 * transmit timer is running and timed sequence 2069 * number was acked, update smoothed round trip time. 2070 * Since we now have an rtt measurement, cancel the 2071 * timer backoff (cf., Phil Karn's retransmit alg.). 2072 * Recompute the initial retransmit timer. 2073 */ 2074 if (opti.ts_present && opti.ts_ecr) 2075 tcp_xmit_timer(tp, TCP_TIMESTAMP(tp) - opti.ts_ecr + 1); 2076 else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) 2077 tcp_xmit_timer(tp, tcp_now - tp->t_rtttime); 2078 2079 /* 2080 * If all outstanding data is acked, stop retransmit 2081 * timer and remember to restart (more output or persist). 2082 * If there is more data to be acked, restart retransmit 2083 * timer, using current (possibly backed-off) value. 2084 */ 2085 if (th->th_ack == tp->snd_max) { 2086 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2087 needoutput = 1; 2088 } else if (TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) 2089 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 2090 /* 2091 * When new data is acked, open the congestion window. 2092 * If the window gives us less than ssthresh packets 2093 * in flight, open exponentially (segsz per packet). 2094 * Otherwise open linearly: segsz per window 2095 * (segsz^2 / cwnd per packet), plus a constant 2096 * fraction of a packet (segsz/8) to help larger windows 2097 * open quickly enough. 2098 */ 2099 { 2100 u_int cw = tp->snd_cwnd; 2101 u_int incr = tp->t_segsz; 2102 2103 if (cw > tp->snd_ssthresh) 2104 incr = incr * incr / cw; 2105 if (tcp_do_newreno == 0 || SEQ_GEQ(th->th_ack, tp->snd_recover)) 2106 tp->snd_cwnd = min(cw + incr, 2107 TCP_MAXWIN << tp->snd_scale); 2108 } 2109 ND6_HINT(tp); 2110 if (acked > so->so_snd.sb_cc) { 2111 tp->snd_wnd -= so->so_snd.sb_cc; 2112 sbdrop(&so->so_snd, (int)so->so_snd.sb_cc); 2113 ourfinisacked = 1; 2114 } else { 2115 if (acked > (tp->t_lastoff - tp->t_inoff)) 2116 tp->t_lastm = NULL; 2117 sbdrop(&so->so_snd, acked); 2118 tp->t_lastoff -= acked; 2119 ourfinisacked = 0; 2120 } 2121 sowwakeup(so); 2122 /* 2123 * We want snd_recover to track snd_una to 2124 * avoid sequence wraparound problems for 2125 * very large transfers. 2126 */ 2127 tp->snd_una = tp->snd_recover = th->th_ack; 2128 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2129 tp->snd_nxt = tp->snd_una; 2130 2131 switch (tp->t_state) { 2132 2133 /* 2134 * In FIN_WAIT_1 STATE in addition to the processing 2135 * for the ESTABLISHED state if our FIN is now acknowledged 2136 * then enter FIN_WAIT_2. 2137 */ 2138 case TCPS_FIN_WAIT_1: 2139 if (ourfinisacked) { 2140 /* 2141 * If we can't receive any more 2142 * data, then closing user can proceed. 2143 * Starting the timer is contrary to the 2144 * specification, but if we don't get a FIN 2145 * we'll hang forever. 2146 */ 2147 if (so->so_state & SS_CANTRCVMORE) { 2148 soisdisconnected(so); 2149 if (tcp_maxidle > 0) 2150 TCP_TIMER_ARM(tp, TCPT_2MSL, 2151 tcp_maxidle); 2152 } 2153 tp->t_state = TCPS_FIN_WAIT_2; 2154 } 2155 break; 2156 2157 /* 2158 * In CLOSING STATE in addition to the processing for 2159 * the ESTABLISHED state if the ACK acknowledges our FIN 2160 * then enter the TIME-WAIT state, otherwise ignore 2161 * the segment. 2162 */ 2163 case TCPS_CLOSING: 2164 if (ourfinisacked) { 2165 tp->t_state = TCPS_TIME_WAIT; 2166 tcp_canceltimers(tp); 2167 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 2168 soisdisconnected(so); 2169 } 2170 break; 2171 2172 /* 2173 * In LAST_ACK, we may still be waiting for data to drain 2174 * and/or to be acked, as well as for the ack of our FIN. 2175 * If our FIN is now acknowledged, delete the TCB, 2176 * enter the closed state and return. 2177 */ 2178 case TCPS_LAST_ACK: 2179 if (ourfinisacked) { 2180 tp = tcp_close(tp); 2181 goto drop; 2182 } 2183 break; 2184 2185 /* 2186 * In TIME_WAIT state the only thing that should arrive 2187 * is a retransmission of the remote FIN. Acknowledge 2188 * it and restart the finack timer. 2189 */ 2190 case TCPS_TIME_WAIT: 2191 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 2192 goto dropafterack; 2193 } 2194 } 2195 2196 step6: 2197 /* 2198 * Update window information. 2199 * Don't look at window if no ACK: TAC's send garbage on first SYN. 2200 */ 2201 if ((tiflags & TH_ACK) && (SEQ_LT(tp->snd_wl1, th->th_seq) || 2202 (tp->snd_wl1 == th->th_seq && SEQ_LT(tp->snd_wl2, th->th_ack)) || 2203 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))) { 2204 /* keep track of pure window updates */ 2205 if (tlen == 0 && 2206 tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) 2207 tcpstat.tcps_rcvwinupd++; 2208 tp->snd_wnd = tiwin; 2209 tp->snd_wl1 = th->th_seq; 2210 tp->snd_wl2 = th->th_ack; 2211 if (tp->snd_wnd > tp->max_sndwnd) 2212 tp->max_sndwnd = tp->snd_wnd; 2213 needoutput = 1; 2214 } 2215 2216 /* 2217 * Process segments with URG. 2218 */ 2219 if ((tiflags & TH_URG) && th->th_urp && 2220 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2221 /* 2222 * This is a kludge, but if we receive and accept 2223 * random urgent pointers, we'll crash in 2224 * soreceive. It's hard to imagine someone 2225 * actually wanting to send this much urgent data. 2226 */ 2227 if (th->th_urp + so->so_rcv.sb_cc > sb_max) { 2228 th->th_urp = 0; /* XXX */ 2229 tiflags &= ~TH_URG; /* XXX */ 2230 goto dodata; /* XXX */ 2231 } 2232 /* 2233 * If this segment advances the known urgent pointer, 2234 * then mark the data stream. This should not happen 2235 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 2236 * a FIN has been received from the remote side. 2237 * In these states we ignore the URG. 2238 * 2239 * According to RFC961 (Assigned Protocols), 2240 * the urgent pointer points to the last octet 2241 * of urgent data. We continue, however, 2242 * to consider it to indicate the first octet 2243 * of data past the urgent section as the original 2244 * spec states (in one of two places). 2245 */ 2246 if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) { 2247 tp->rcv_up = th->th_seq + th->th_urp; 2248 so->so_oobmark = so->so_rcv.sb_cc + 2249 (tp->rcv_up - tp->rcv_nxt) - 1; 2250 if (so->so_oobmark == 0) 2251 so->so_state |= SS_RCVATMARK; 2252 sohasoutofband(so); 2253 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); 2254 } 2255 /* 2256 * Remove out of band data so doesn't get presented to user. 2257 * This can happen independent of advancing the URG pointer, 2258 * but if two URG's are pending at once, some out-of-band 2259 * data may creep in... ick. 2260 */ 2261 if (th->th_urp <= (u_int16_t) tlen 2262 #ifdef SO_OOBINLINE 2263 && (so->so_options & SO_OOBINLINE) == 0 2264 #endif 2265 ) 2266 tcp_pulloutofband(so, th, m, hdroptlen); 2267 } else 2268 /* 2269 * If no out of band data is expected, 2270 * pull receive urgent pointer along 2271 * with the receive window. 2272 */ 2273 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) 2274 tp->rcv_up = tp->rcv_nxt; 2275 dodata: /* XXX */ 2276 2277 /* 2278 * Process the segment text, merging it into the TCP sequencing queue, 2279 * and arranging for acknowledgement of receipt if necessary. 2280 * This process logically involves adjusting tp->rcv_wnd as data 2281 * is presented to the user (this happens in tcp_usrreq.c, 2282 * case PRU_RCVD). If a FIN has already been received on this 2283 * connection then we just ignore the text. 2284 */ 2285 if ((tlen || (tiflags & TH_FIN)) && 2286 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2287 /* 2288 * Insert segment ti into reassembly queue of tcp with 2289 * control block tp. Return TH_FIN if reassembly now includes 2290 * a segment with FIN. The macro form does the common case 2291 * inline (segment is the next to be received on an 2292 * established connection, and the queue is empty), 2293 * avoiding linkage into and removal from the queue and 2294 * repetition of various conversions. 2295 * Set DELACK for segments received in order, but ack 2296 * immediately when segments are out of order 2297 * (so fast retransmit can work). 2298 */ 2299 /* NOTE: this was TCP_REASS() macro, but used only once */ 2300 TCP_REASS_LOCK(tp); 2301 if (th->th_seq == tp->rcv_nxt && 2302 TAILQ_FIRST(&tp->segq) == NULL && 2303 tp->t_state == TCPS_ESTABLISHED) { 2304 TCP_SETUP_ACK(tp, th); 2305 tp->rcv_nxt += tlen; 2306 tiflags = th->th_flags & TH_FIN; 2307 tcpstat.tcps_rcvpack++; 2308 tcpstat.tcps_rcvbyte += tlen; 2309 ND6_HINT(tp); 2310 if (so->so_state & SS_CANTRCVMORE) 2311 m_freem(m); 2312 else { 2313 m_adj(m, hdroptlen); 2314 sbappendstream(&(so)->so_rcv, m); 2315 } 2316 sorwakeup(so); 2317 } else { 2318 m_adj(m, hdroptlen); 2319 tiflags = tcp_reass(tp, th, m, &tlen); 2320 tp->t_flags |= TF_ACKNOW; 2321 } 2322 TCP_REASS_UNLOCK(tp); 2323 2324 /* 2325 * Note the amount of data that peer has sent into 2326 * our window, in order to estimate the sender's 2327 * buffer size. 2328 */ 2329 len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); 2330 } else { 2331 m_freem(m); 2332 m = NULL; 2333 tiflags &= ~TH_FIN; 2334 } 2335 2336 /* 2337 * If FIN is received ACK the FIN and let the user know 2338 * that the connection is closing. Ignore a FIN received before 2339 * the connection is fully established. 2340 */ 2341 if ((tiflags & TH_FIN) && TCPS_HAVEESTABLISHED(tp->t_state)) { 2342 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2343 socantrcvmore(so); 2344 tp->t_flags |= TF_ACKNOW; 2345 tp->rcv_nxt++; 2346 } 2347 switch (tp->t_state) { 2348 2349 /* 2350 * In ESTABLISHED STATE enter the CLOSE_WAIT state. 2351 */ 2352 case TCPS_ESTABLISHED: 2353 tp->t_state = TCPS_CLOSE_WAIT; 2354 break; 2355 2356 /* 2357 * If still in FIN_WAIT_1 STATE FIN has not been acked so 2358 * enter the CLOSING state. 2359 */ 2360 case TCPS_FIN_WAIT_1: 2361 tp->t_state = TCPS_CLOSING; 2362 break; 2363 2364 /* 2365 * In FIN_WAIT_2 state enter the TIME_WAIT state, 2366 * starting the time-wait timer, turning off the other 2367 * standard timers. 2368 */ 2369 case TCPS_FIN_WAIT_2: 2370 tp->t_state = TCPS_TIME_WAIT; 2371 tcp_canceltimers(tp); 2372 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 2373 soisdisconnected(so); 2374 break; 2375 2376 /* 2377 * In TIME_WAIT state restart the 2 MSL time_wait timer. 2378 */ 2379 case TCPS_TIME_WAIT: 2380 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 2381 break; 2382 } 2383 } 2384 #ifdef TCP_DEBUG 2385 if (so->so_options & SO_DEBUG) 2386 tcp_trace(TA_INPUT, ostate, tp, tcp_saveti, 0); 2387 #endif 2388 2389 /* 2390 * Return any desired output. 2391 */ 2392 if (needoutput || (tp->t_flags & TF_ACKNOW)) 2393 (void) tcp_output(tp); 2394 if (tcp_saveti) 2395 m_freem(tcp_saveti); 2396 return; 2397 2398 badsyn: 2399 /* 2400 * Received a bad SYN. Increment counters and dropwithreset. 2401 */ 2402 tcpstat.tcps_badsyn++; 2403 tp = NULL; 2404 goto dropwithreset; 2405 2406 dropafterack: 2407 /* 2408 * Generate an ACK dropping incoming segment if it occupies 2409 * sequence space, where the ACK reflects our state. 2410 */ 2411 if (tiflags & TH_RST) 2412 goto drop; 2413 m_freem(m); 2414 tp->t_flags |= TF_ACKNOW; 2415 (void) tcp_output(tp); 2416 if (tcp_saveti) 2417 m_freem(tcp_saveti); 2418 return; 2419 2420 dropwithreset_ratelim: 2421 /* 2422 * We may want to rate-limit RSTs in certain situations, 2423 * particularly if we are sending an RST in response to 2424 * an attempt to connect to or otherwise communicate with 2425 * a port for which we have no socket. 2426 */ 2427 if (ppsratecheck(&tcp_rst_ppslim_last, &tcp_rst_ppslim_count, 2428 tcp_rst_ppslim) == 0) { 2429 /* XXX stat */ 2430 goto drop; 2431 } 2432 /* ...fall into dropwithreset... */ 2433 2434 dropwithreset: 2435 /* 2436 * Generate a RST, dropping incoming segment. 2437 * Make ACK acceptable to originator of segment. 2438 */ 2439 if (tiflags & TH_RST) 2440 goto drop; 2441 2442 switch (af) { 2443 #ifdef INET6 2444 case AF_INET6: 2445 /* For following calls to tcp_respond */ 2446 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) 2447 goto drop; 2448 break; 2449 #endif /* INET6 */ 2450 case AF_INET: 2451 if (IN_MULTICAST(ip->ip_dst.s_addr) || 2452 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 2453 goto drop; 2454 } 2455 2456 if (tiflags & TH_ACK) 2457 (void)tcp_respond(tp, m, m, th, (tcp_seq)0, th->th_ack, TH_RST); 2458 else { 2459 if (tiflags & TH_SYN) 2460 tlen++; 2461 (void)tcp_respond(tp, m, m, th, th->th_seq + tlen, (tcp_seq)0, 2462 TH_RST|TH_ACK); 2463 } 2464 if (tcp_saveti) 2465 m_freem(tcp_saveti); 2466 return; 2467 2468 badcsum: 2469 tcpstat.tcps_rcvbadsum++; 2470 drop: 2471 /* 2472 * Drop space held by incoming segment and return. 2473 */ 2474 if (tp) { 2475 if (tp->t_inpcb) 2476 so = tp->t_inpcb->inp_socket; 2477 #ifdef INET6 2478 else if (tp->t_in6pcb) 2479 so = tp->t_in6pcb->in6p_socket; 2480 #endif 2481 else 2482 so = NULL; 2483 #ifdef TCP_DEBUG 2484 if (so && (so->so_options & SO_DEBUG) != 0) 2485 tcp_trace(TA_DROP, ostate, tp, tcp_saveti, 0); 2486 #endif 2487 } 2488 if (tcp_saveti) 2489 m_freem(tcp_saveti); 2490 m_freem(m); 2491 return; 2492 } 2493 2494 void 2495 tcp_dooptions(tp, cp, cnt, th, oi) 2496 struct tcpcb *tp; 2497 u_char *cp; 2498 int cnt; 2499 struct tcphdr *th; 2500 struct tcp_opt_info *oi; 2501 { 2502 u_int16_t mss; 2503 int opt, optlen; 2504 2505 for (; cnt > 0; cnt -= optlen, cp += optlen) { 2506 opt = cp[0]; 2507 if (opt == TCPOPT_EOL) 2508 break; 2509 if (opt == TCPOPT_NOP) 2510 optlen = 1; 2511 else { 2512 if (cnt < 2) 2513 break; 2514 optlen = cp[1]; 2515 if (optlen < 2 || optlen > cnt) 2516 break; 2517 } 2518 switch (opt) { 2519 2520 default: 2521 continue; 2522 2523 case TCPOPT_MAXSEG: 2524 if (optlen != TCPOLEN_MAXSEG) 2525 continue; 2526 if (!(th->th_flags & TH_SYN)) 2527 continue; 2528 bcopy(cp + 2, &mss, sizeof(mss)); 2529 oi->maxseg = ntohs(mss); 2530 break; 2531 2532 case TCPOPT_WINDOW: 2533 if (optlen != TCPOLEN_WINDOW) 2534 continue; 2535 if (!(th->th_flags & TH_SYN)) 2536 continue; 2537 tp->t_flags |= TF_RCVD_SCALE; 2538 tp->requested_s_scale = cp[2]; 2539 if (tp->requested_s_scale > TCP_MAX_WINSHIFT) { 2540 #if 0 /*XXX*/ 2541 char *p; 2542 2543 if (ip) 2544 p = ntohl(ip->ip_src); 2545 #ifdef INET6 2546 else if (ip6) 2547 p = ip6_sprintf(&ip6->ip6_src); 2548 #endif 2549 else 2550 p = "(unknown)"; 2551 log(LOG_ERR, "TCP: invalid wscale %d from %s, " 2552 "assuming %d\n", 2553 tp->requested_s_scale, p, 2554 TCP_MAX_WINSHIFT); 2555 #else 2556 log(LOG_ERR, "TCP: invalid wscale %d, " 2557 "assuming %d\n", 2558 tp->requested_s_scale, 2559 TCP_MAX_WINSHIFT); 2560 #endif 2561 tp->requested_s_scale = TCP_MAX_WINSHIFT; 2562 } 2563 break; 2564 2565 case TCPOPT_TIMESTAMP: 2566 if (optlen != TCPOLEN_TIMESTAMP) 2567 continue; 2568 oi->ts_present = 1; 2569 bcopy(cp + 2, &oi->ts_val, sizeof(oi->ts_val)); 2570 NTOHL(oi->ts_val); 2571 bcopy(cp + 6, &oi->ts_ecr, sizeof(oi->ts_ecr)); 2572 NTOHL(oi->ts_ecr); 2573 2574 /* 2575 * A timestamp received in a SYN makes 2576 * it ok to send timestamp requests and replies. 2577 */ 2578 if (th->th_flags & TH_SYN) { 2579 tp->t_flags |= TF_RCVD_TSTMP; 2580 tp->ts_recent = oi->ts_val; 2581 tp->ts_recent_age = TCP_TIMESTAMP(tp); 2582 } 2583 break; 2584 case TCPOPT_SACK_PERMITTED: 2585 if (optlen != TCPOLEN_SACK_PERMITTED) 2586 continue; 2587 if (!(th->th_flags & TH_SYN)) 2588 continue; 2589 tp->t_flags &= ~TF_CANT_TXSACK; 2590 break; 2591 2592 case TCPOPT_SACK: 2593 if (tp->t_flags & TF_IGNR_RXSACK) 2594 continue; 2595 if (optlen % 8 != 2 || optlen < 10) 2596 continue; 2597 cp += 2; 2598 optlen -= 2; 2599 for (; optlen > 0; cp -= 8, optlen -= 8) { 2600 tcp_seq lwe, rwe; 2601 bcopy((char *)cp, (char *) &lwe, sizeof(lwe)); 2602 NTOHL(lwe); 2603 bcopy((char *)cp, (char *) &rwe, sizeof(rwe)); 2604 NTOHL(rwe); 2605 /* tcp_mark_sacked(tp, lwe, rwe); */ 2606 } 2607 break; 2608 } 2609 } 2610 } 2611 2612 /* 2613 * Pull out of band byte out of a segment so 2614 * it doesn't appear in the user's data queue. 2615 * It is still reflected in the segment length for 2616 * sequencing purposes. 2617 */ 2618 void 2619 tcp_pulloutofband(so, th, m, off) 2620 struct socket *so; 2621 struct tcphdr *th; 2622 struct mbuf *m; 2623 int off; 2624 { 2625 int cnt = off + th->th_urp - 1; 2626 2627 while (cnt >= 0) { 2628 if (m->m_len > cnt) { 2629 char *cp = mtod(m, caddr_t) + cnt; 2630 struct tcpcb *tp = sototcpcb(so); 2631 2632 tp->t_iobc = *cp; 2633 tp->t_oobflags |= TCPOOB_HAVEDATA; 2634 bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); 2635 m->m_len--; 2636 return; 2637 } 2638 cnt -= m->m_len; 2639 m = m->m_next; 2640 if (m == 0) 2641 break; 2642 } 2643 panic("tcp_pulloutofband"); 2644 } 2645 2646 /* 2647 * Collect new round-trip time estimate 2648 * and update averages and current timeout. 2649 */ 2650 void 2651 tcp_xmit_timer(tp, rtt) 2652 struct tcpcb *tp; 2653 uint32_t rtt; 2654 { 2655 int32_t delta; 2656 2657 tcpstat.tcps_rttupdated++; 2658 if (tp->t_srtt != 0) { 2659 /* 2660 * srtt is stored as fixed point with 3 bits after the 2661 * binary point (i.e., scaled by 8). The following magic 2662 * is equivalent to the smoothing algorithm in rfc793 with 2663 * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed 2664 * point). Adjust rtt to origin 0. 2665 */ 2666 delta = (rtt << 2) - (tp->t_srtt >> TCP_RTT_SHIFT); 2667 if ((tp->t_srtt += delta) <= 0) 2668 tp->t_srtt = 1 << 2; 2669 /* 2670 * We accumulate a smoothed rtt variance (actually, a 2671 * smoothed mean difference), then set the retransmit 2672 * timer to smoothed rtt + 4 times the smoothed variance. 2673 * rttvar is stored as fixed point with 2 bits after the 2674 * binary point (scaled by 4). The following is 2675 * equivalent to rfc793 smoothing with an alpha of .75 2676 * (rttvar = rttvar*3/4 + |delta| / 4). This replaces 2677 * rfc793's wired-in beta. 2678 */ 2679 if (delta < 0) 2680 delta = -delta; 2681 delta -= (tp->t_rttvar >> TCP_RTTVAR_SHIFT); 2682 if ((tp->t_rttvar += delta) <= 0) 2683 tp->t_rttvar = 1 << 2; 2684 } else { 2685 /* 2686 * No rtt measurement yet - use the unsmoothed rtt. 2687 * Set the variance to half the rtt (so our first 2688 * retransmit happens at 3*rtt). 2689 */ 2690 tp->t_srtt = rtt << (TCP_RTT_SHIFT + 2); 2691 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT + 2 - 1); 2692 } 2693 tp->t_rtttime = 0; 2694 tp->t_rxtshift = 0; 2695 2696 /* 2697 * the retransmit should happen at rtt + 4 * rttvar. 2698 * Because of the way we do the smoothing, srtt and rttvar 2699 * will each average +1/2 tick of bias. When we compute 2700 * the retransmit timer, we want 1/2 tick of rounding and 2701 * 1 extra tick because of +-1/2 tick uncertainty in the 2702 * firing of the timer. The bias will give us exactly the 2703 * 1.5 tick we need. But, because the bias is 2704 * statistical, we have to test that we don't drop below 2705 * the minimum feasible timer (which is 2 ticks). 2706 */ 2707 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), 2708 max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX); 2709 2710 /* 2711 * We received an ack for a packet that wasn't retransmitted; 2712 * it is probably safe to discard any error indications we've 2713 * received recently. This isn't quite right, but close enough 2714 * for now (a route might have failed after we sent a segment, 2715 * and the return path might not be symmetrical). 2716 */ 2717 tp->t_softerror = 0; 2718 } 2719 2720 /* 2721 * Checks for partial ack. If partial ack arrives, force the retransmission 2722 * of the next unacknowledged segment, do not clear tp->t_dupacks, and return 2723 * 1. By setting snd_nxt to th_ack, this forces retransmission timer to 2724 * be started again. If the ack advances at least to tp->snd_recover, return 0. 2725 */ 2726 int 2727 tcp_newreno(tp, th) 2728 struct tcpcb *tp; 2729 struct tcphdr *th; 2730 { 2731 tcp_seq onxt = tp->snd_nxt; 2732 u_long ocwnd = tp->snd_cwnd; 2733 2734 if (SEQ_LT(th->th_ack, tp->snd_recover)) { 2735 /* 2736 * snd_una has not yet been updated and the socket's send 2737 * buffer has not yet drained off the ACK'd data, so we 2738 * have to leave snd_una as it was to get the correct data 2739 * offset in tcp_output(). 2740 */ 2741 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2742 tp->t_rtttime = 0; 2743 tp->snd_nxt = th->th_ack; 2744 /* 2745 * Set snd_cwnd to one segment beyond ACK'd offset. snd_una 2746 * is not yet updated when we're called. 2747 */ 2748 tp->snd_cwnd = tp->t_segsz + (th->th_ack - tp->snd_una); 2749 (void) tcp_output(tp); 2750 tp->snd_cwnd = ocwnd; 2751 if (SEQ_GT(onxt, tp->snd_nxt)) 2752 tp->snd_nxt = onxt; 2753 /* 2754 * Partial window deflation. Relies on fact that tp->snd_una 2755 * not updated yet. 2756 */ 2757 tp->snd_cwnd -= (th->th_ack - tp->snd_una - tp->t_segsz); 2758 return 1; 2759 } 2760 return 0; 2761 } 2762 2763 2764 /* 2765 * TCP compressed state engine. Currently used to hold compressed 2766 * state for SYN_RECEIVED. 2767 */ 2768 2769 u_long syn_cache_count; 2770 u_int32_t syn_hash1, syn_hash2; 2771 2772 #define SYN_HASH(sa, sp, dp) \ 2773 ((((sa)->s_addr^syn_hash1)*(((((u_int32_t)(dp))<<16) + \ 2774 ((u_int32_t)(sp)))^syn_hash2))) 2775 #ifndef INET6 2776 #define SYN_HASHALL(hash, src, dst) \ 2777 do { \ 2778 hash = SYN_HASH(&((struct sockaddr_in *)(src))->sin_addr, \ 2779 ((struct sockaddr_in *)(src))->sin_port, \ 2780 ((struct sockaddr_in *)(dst))->sin_port); \ 2781 } while (/*CONSTCOND*/ 0) 2782 #else 2783 #define SYN_HASH6(sa, sp, dp) \ 2784 ((((sa)->s6_addr32[0] ^ (sa)->s6_addr32[3] ^ syn_hash1) * \ 2785 (((((u_int32_t)(dp))<<16) + ((u_int32_t)(sp)))^syn_hash2)) \ 2786 & 0x7fffffff) 2787 2788 #define SYN_HASHALL(hash, src, dst) \ 2789 do { \ 2790 switch ((src)->sa_family) { \ 2791 case AF_INET: \ 2792 hash = SYN_HASH(&((struct sockaddr_in *)(src))->sin_addr, \ 2793 ((struct sockaddr_in *)(src))->sin_port, \ 2794 ((struct sockaddr_in *)(dst))->sin_port); \ 2795 break; \ 2796 case AF_INET6: \ 2797 hash = SYN_HASH6(&((struct sockaddr_in6 *)(src))->sin6_addr, \ 2798 ((struct sockaddr_in6 *)(src))->sin6_port, \ 2799 ((struct sockaddr_in6 *)(dst))->sin6_port); \ 2800 break; \ 2801 default: \ 2802 hash = 0; \ 2803 } \ 2804 } while (/*CONSTCOND*/0) 2805 #endif /* INET6 */ 2806 2807 #define SYN_CACHE_RM(sc) \ 2808 do { \ 2809 TAILQ_REMOVE(&tcp_syn_cache[(sc)->sc_bucketidx].sch_bucket, \ 2810 (sc), sc_bucketq); \ 2811 (sc)->sc_tp = NULL; \ 2812 LIST_REMOVE((sc), sc_tpq); \ 2813 tcp_syn_cache[(sc)->sc_bucketidx].sch_length--; \ 2814 callout_stop(&(sc)->sc_timer); \ 2815 syn_cache_count--; \ 2816 } while (/*CONSTCOND*/0) 2817 2818 #define SYN_CACHE_PUT(sc) \ 2819 do { \ 2820 if ((sc)->sc_ipopts) \ 2821 (void) m_free((sc)->sc_ipopts); \ 2822 if ((sc)->sc_route4.ro_rt != NULL) \ 2823 RTFREE((sc)->sc_route4.ro_rt); \ 2824 if (callout_invoking(&(sc)->sc_timer)) \ 2825 (sc)->sc_flags |= SCF_DEAD; \ 2826 else \ 2827 pool_put(&syn_cache_pool, (sc)); \ 2828 } while (/*CONSTCOND*/0) 2829 2830 struct pool syn_cache_pool; 2831 2832 /* 2833 * We don't estimate RTT with SYNs, so each packet starts with the default 2834 * RTT and each timer step has a fixed timeout value. 2835 */ 2836 #define SYN_CACHE_TIMER_ARM(sc) \ 2837 do { \ 2838 TCPT_RANGESET((sc)->sc_rxtcur, \ 2839 TCPTV_SRTTDFLT * tcp_backoff[(sc)->sc_rxtshift], TCPTV_MIN, \ 2840 TCPTV_REXMTMAX); \ 2841 callout_reset(&(sc)->sc_timer, \ 2842 (sc)->sc_rxtcur * (hz / PR_SLOWHZ), syn_cache_timer, (sc)); \ 2843 } while (/*CONSTCOND*/0) 2844 2845 #define SYN_CACHE_TIMESTAMP(sc) (tcp_now - (sc)->sc_timebase) 2846 2847 void 2848 syn_cache_init() 2849 { 2850 int i; 2851 2852 /* Initialize the hash buckets. */ 2853 for (i = 0; i < tcp_syn_cache_size; i++) 2854 TAILQ_INIT(&tcp_syn_cache[i].sch_bucket); 2855 2856 /* Initialize the syn cache pool. */ 2857 pool_init(&syn_cache_pool, sizeof(struct syn_cache), 0, 0, 0, 2858 "synpl", NULL); 2859 } 2860 2861 void 2862 syn_cache_insert(sc, tp) 2863 struct syn_cache *sc; 2864 struct tcpcb *tp; 2865 { 2866 struct syn_cache_head *scp; 2867 struct syn_cache *sc2; 2868 int s; 2869 2870 /* 2871 * If there are no entries in the hash table, reinitialize 2872 * the hash secrets. 2873 */ 2874 if (syn_cache_count == 0) { 2875 struct timeval tv; 2876 microtime(&tv); 2877 syn_hash1 = arc4random() ^ (u_long)≻ 2878 syn_hash2 = arc4random() ^ tv.tv_usec; 2879 } 2880 2881 SYN_HASHALL(sc->sc_hash, &sc->sc_src.sa, &sc->sc_dst.sa); 2882 sc->sc_bucketidx = sc->sc_hash % tcp_syn_cache_size; 2883 scp = &tcp_syn_cache[sc->sc_bucketidx]; 2884 2885 /* 2886 * Make sure that we don't overflow the per-bucket 2887 * limit or the total cache size limit. 2888 */ 2889 s = splsoftnet(); 2890 if (scp->sch_length >= tcp_syn_bucket_limit) { 2891 tcpstat.tcps_sc_bucketoverflow++; 2892 /* 2893 * The bucket is full. Toss the oldest element in the 2894 * bucket. This will be the first entry in the bucket. 2895 */ 2896 sc2 = TAILQ_FIRST(&scp->sch_bucket); 2897 #ifdef DIAGNOSTIC 2898 /* 2899 * This should never happen; we should always find an 2900 * entry in our bucket. 2901 */ 2902 if (sc2 == NULL) 2903 panic("syn_cache_insert: bucketoverflow: impossible"); 2904 #endif 2905 SYN_CACHE_RM(sc2); 2906 SYN_CACHE_PUT(sc2); 2907 } else if (syn_cache_count >= tcp_syn_cache_limit) { 2908 struct syn_cache_head *scp2, *sce; 2909 2910 tcpstat.tcps_sc_overflowed++; 2911 /* 2912 * The cache is full. Toss the oldest entry in the 2913 * first non-empty bucket we can find. 2914 * 2915 * XXX We would really like to toss the oldest 2916 * entry in the cache, but we hope that this 2917 * condition doesn't happen very often. 2918 */ 2919 scp2 = scp; 2920 if (TAILQ_EMPTY(&scp2->sch_bucket)) { 2921 sce = &tcp_syn_cache[tcp_syn_cache_size]; 2922 for (++scp2; scp2 != scp; scp2++) { 2923 if (scp2 >= sce) 2924 scp2 = &tcp_syn_cache[0]; 2925 if (! TAILQ_EMPTY(&scp2->sch_bucket)) 2926 break; 2927 } 2928 #ifdef DIAGNOSTIC 2929 /* 2930 * This should never happen; we should always find a 2931 * non-empty bucket. 2932 */ 2933 if (scp2 == scp) 2934 panic("syn_cache_insert: cacheoverflow: " 2935 "impossible"); 2936 #endif 2937 } 2938 sc2 = TAILQ_FIRST(&scp2->sch_bucket); 2939 SYN_CACHE_RM(sc2); 2940 SYN_CACHE_PUT(sc2); 2941 } 2942 2943 /* 2944 * Initialize the entry's timer. 2945 */ 2946 sc->sc_rxttot = 0; 2947 sc->sc_rxtshift = 0; 2948 SYN_CACHE_TIMER_ARM(sc); 2949 2950 /* Link it from tcpcb entry */ 2951 LIST_INSERT_HEAD(&tp->t_sc, sc, sc_tpq); 2952 2953 /* Put it into the bucket. */ 2954 TAILQ_INSERT_TAIL(&scp->sch_bucket, sc, sc_bucketq); 2955 scp->sch_length++; 2956 syn_cache_count++; 2957 2958 tcpstat.tcps_sc_added++; 2959 splx(s); 2960 } 2961 2962 /* 2963 * Walk the timer queues, looking for SYN,ACKs that need to be retransmitted. 2964 * If we have retransmitted an entry the maximum number of times, expire 2965 * that entry. 2966 */ 2967 void 2968 syn_cache_timer(void *arg) 2969 { 2970 struct syn_cache *sc = arg; 2971 int s; 2972 2973 s = splsoftnet(); 2974 callout_ack(&sc->sc_timer); 2975 2976 if (__predict_false(sc->sc_flags & SCF_DEAD)) { 2977 tcpstat.tcps_sc_delayed_free++; 2978 pool_put(&syn_cache_pool, sc); 2979 splx(s); 2980 return; 2981 } 2982 2983 if (__predict_false(sc->sc_rxtshift == TCP_MAXRXTSHIFT)) { 2984 /* Drop it -- too many retransmissions. */ 2985 goto dropit; 2986 } 2987 2988 /* 2989 * Compute the total amount of time this entry has 2990 * been on a queue. If this entry has been on longer 2991 * than the keep alive timer would allow, expire it. 2992 */ 2993 sc->sc_rxttot += sc->sc_rxtcur; 2994 if (sc->sc_rxttot >= TCPTV_KEEP_INIT) 2995 goto dropit; 2996 2997 tcpstat.tcps_sc_retransmitted++; 2998 (void) syn_cache_respond(sc, NULL); 2999 3000 /* Advance the timer back-off. */ 3001 sc->sc_rxtshift++; 3002 SYN_CACHE_TIMER_ARM(sc); 3003 3004 splx(s); 3005 return; 3006 3007 dropit: 3008 tcpstat.tcps_sc_timed_out++; 3009 SYN_CACHE_RM(sc); 3010 SYN_CACHE_PUT(sc); 3011 splx(s); 3012 } 3013 3014 /* 3015 * Remove syn cache created by the specified tcb entry, 3016 * because this does not make sense to keep them 3017 * (if there's no tcb entry, syn cache entry will never be used) 3018 */ 3019 void 3020 syn_cache_cleanup(tp) 3021 struct tcpcb *tp; 3022 { 3023 struct syn_cache *sc, *nsc; 3024 int s; 3025 3026 s = splsoftnet(); 3027 3028 for (sc = LIST_FIRST(&tp->t_sc); sc != NULL; sc = nsc) { 3029 nsc = LIST_NEXT(sc, sc_tpq); 3030 3031 #ifdef DIAGNOSTIC 3032 if (sc->sc_tp != tp) 3033 panic("invalid sc_tp in syn_cache_cleanup"); 3034 #endif 3035 SYN_CACHE_RM(sc); 3036 SYN_CACHE_PUT(sc); 3037 } 3038 /* just for safety */ 3039 LIST_INIT(&tp->t_sc); 3040 3041 splx(s); 3042 } 3043 3044 /* 3045 * Find an entry in the syn cache. 3046 */ 3047 struct syn_cache * 3048 syn_cache_lookup(src, dst, headp) 3049 struct sockaddr *src; 3050 struct sockaddr *dst; 3051 struct syn_cache_head **headp; 3052 { 3053 struct syn_cache *sc; 3054 struct syn_cache_head *scp; 3055 u_int32_t hash; 3056 int s; 3057 3058 SYN_HASHALL(hash, src, dst); 3059 3060 scp = &tcp_syn_cache[hash % tcp_syn_cache_size]; 3061 *headp = scp; 3062 s = splsoftnet(); 3063 for (sc = TAILQ_FIRST(&scp->sch_bucket); sc != NULL; 3064 sc = TAILQ_NEXT(sc, sc_bucketq)) { 3065 if (sc->sc_hash != hash) 3066 continue; 3067 if (!bcmp(&sc->sc_src, src, src->sa_len) && 3068 !bcmp(&sc->sc_dst, dst, dst->sa_len)) { 3069 splx(s); 3070 return (sc); 3071 } 3072 } 3073 splx(s); 3074 return (NULL); 3075 } 3076 3077 /* 3078 * This function gets called when we receive an ACK for a 3079 * socket in the LISTEN state. We look up the connection 3080 * in the syn cache, and if its there, we pull it out of 3081 * the cache and turn it into a full-blown connection in 3082 * the SYN-RECEIVED state. 3083 * 3084 * The return values may not be immediately obvious, and their effects 3085 * can be subtle, so here they are: 3086 * 3087 * NULL SYN was not found in cache; caller should drop the 3088 * packet and send an RST. 3089 * 3090 * -1 We were unable to create the new connection, and are 3091 * aborting it. An ACK,RST is being sent to the peer 3092 * (unless we got screwey sequence numbners; see below), 3093 * because the 3-way handshake has been completed. Caller 3094 * should not free the mbuf, since we may be using it. If 3095 * we are not, we will free it. 3096 * 3097 * Otherwise, the return value is a pointer to the new socket 3098 * associated with the connection. 3099 */ 3100 struct socket * 3101 syn_cache_get(src, dst, th, hlen, tlen, so, m) 3102 struct sockaddr *src; 3103 struct sockaddr *dst; 3104 struct tcphdr *th; 3105 unsigned int hlen, tlen; 3106 struct socket *so; 3107 struct mbuf *m; 3108 { 3109 struct syn_cache *sc; 3110 struct syn_cache_head *scp; 3111 struct inpcb *inp = NULL; 3112 #ifdef INET6 3113 struct in6pcb *in6p = NULL; 3114 #endif 3115 struct tcpcb *tp = 0; 3116 struct mbuf *am; 3117 int s; 3118 struct socket *oso; 3119 3120 s = splsoftnet(); 3121 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 3122 splx(s); 3123 return (NULL); 3124 } 3125 3126 /* 3127 * Verify the sequence and ack numbers. Try getting the correct 3128 * response again. 3129 */ 3130 if ((th->th_ack != sc->sc_iss + 1) || 3131 SEQ_LEQ(th->th_seq, sc->sc_irs) || 3132 SEQ_GT(th->th_seq, sc->sc_irs + 1 + sc->sc_win)) { 3133 (void) syn_cache_respond(sc, m); 3134 splx(s); 3135 return ((struct socket *)(-1)); 3136 } 3137 3138 /* Remove this cache entry */ 3139 SYN_CACHE_RM(sc); 3140 splx(s); 3141 3142 /* 3143 * Ok, create the full blown connection, and set things up 3144 * as they would have been set up if we had created the 3145 * connection when the SYN arrived. If we can't create 3146 * the connection, abort it. 3147 */ 3148 /* 3149 * inp still has the OLD in_pcb stuff, set the 3150 * v6-related flags on the new guy, too. This is 3151 * done particularly for the case where an AF_INET6 3152 * socket is bound only to a port, and a v4 connection 3153 * comes in on that port. 3154 * we also copy the flowinfo from the original pcb 3155 * to the new one. 3156 */ 3157 oso = so; 3158 so = sonewconn(so, SS_ISCONNECTED); 3159 if (so == NULL) 3160 goto resetandabort; 3161 3162 switch (so->so_proto->pr_domain->dom_family) { 3163 #ifdef INET 3164 case AF_INET: 3165 inp = sotoinpcb(so); 3166 break; 3167 #endif 3168 #ifdef INET6 3169 case AF_INET6: 3170 in6p = sotoin6pcb(so); 3171 break; 3172 #endif 3173 } 3174 switch (src->sa_family) { 3175 #ifdef INET 3176 case AF_INET: 3177 if (inp) { 3178 inp->inp_laddr = ((struct sockaddr_in *)dst)->sin_addr; 3179 inp->inp_lport = ((struct sockaddr_in *)dst)->sin_port; 3180 inp->inp_options = ip_srcroute(); 3181 in_pcbstate(inp, INP_BOUND); 3182 if (inp->inp_options == NULL) { 3183 inp->inp_options = sc->sc_ipopts; 3184 sc->sc_ipopts = NULL; 3185 } 3186 } 3187 #ifdef INET6 3188 else if (in6p) { 3189 /* IPv4 packet to AF_INET6 socket */ 3190 bzero(&in6p->in6p_laddr, sizeof(in6p->in6p_laddr)); 3191 in6p->in6p_laddr.s6_addr16[5] = htons(0xffff); 3192 bcopy(&((struct sockaddr_in *)dst)->sin_addr, 3193 &in6p->in6p_laddr.s6_addr32[3], 3194 sizeof(((struct sockaddr_in *)dst)->sin_addr)); 3195 in6p->in6p_lport = ((struct sockaddr_in *)dst)->sin_port; 3196 in6totcpcb(in6p)->t_family = AF_INET; 3197 if (sotoin6pcb(oso)->in6p_flags & IN6P_IPV6_V6ONLY) 3198 in6p->in6p_flags |= IN6P_IPV6_V6ONLY; 3199 else 3200 in6p->in6p_flags &= ~IN6P_IPV6_V6ONLY; 3201 in6_pcbstate(in6p, IN6P_BOUND); 3202 } 3203 #endif 3204 break; 3205 #endif 3206 #ifdef INET6 3207 case AF_INET6: 3208 if (in6p) { 3209 in6p->in6p_laddr = ((struct sockaddr_in6 *)dst)->sin6_addr; 3210 in6p->in6p_lport = ((struct sockaddr_in6 *)dst)->sin6_port; 3211 in6_pcbstate(in6p, IN6P_BOUND); 3212 } 3213 break; 3214 #endif 3215 } 3216 #ifdef INET6 3217 if (in6p && in6totcpcb(in6p)->t_family == AF_INET6 && sotoinpcb(oso)) { 3218 struct in6pcb *oin6p = sotoin6pcb(oso); 3219 /* inherit socket options from the listening socket */ 3220 in6p->in6p_flags |= (oin6p->in6p_flags & IN6P_CONTROLOPTS); 3221 if (in6p->in6p_flags & IN6P_CONTROLOPTS) { 3222 m_freem(in6p->in6p_options); 3223 in6p->in6p_options = 0; 3224 } 3225 ip6_savecontrol(in6p, &in6p->in6p_options, 3226 mtod(m, struct ip6_hdr *), m); 3227 } 3228 #endif 3229 3230 #if defined(IPSEC) || defined(FAST_IPSEC) 3231 /* 3232 * we make a copy of policy, instead of sharing the policy, 3233 * for better behavior in terms of SA lookup and dead SA removal. 3234 */ 3235 if (inp) { 3236 /* copy old policy into new socket's */ 3237 if (ipsec_copy_pcbpolicy(sotoinpcb(oso)->inp_sp, inp->inp_sp)) 3238 printf("tcp_input: could not copy policy\n"); 3239 } 3240 #ifdef INET6 3241 else if (in6p) { 3242 /* copy old policy into new socket's */ 3243 if (ipsec_copy_pcbpolicy(sotoin6pcb(oso)->in6p_sp, 3244 in6p->in6p_sp)) 3245 printf("tcp_input: could not copy policy\n"); 3246 } 3247 #endif 3248 #endif 3249 3250 /* 3251 * Give the new socket our cached route reference. 3252 */ 3253 if (inp) 3254 inp->inp_route = sc->sc_route4; /* struct assignment */ 3255 #ifdef INET6 3256 else 3257 in6p->in6p_route = sc->sc_route6; 3258 #endif 3259 sc->sc_route4.ro_rt = NULL; 3260 3261 am = m_get(M_DONTWAIT, MT_SONAME); /* XXX */ 3262 if (am == NULL) 3263 goto resetandabort; 3264 MCLAIM(am, &tcp_mowner); 3265 am->m_len = src->sa_len; 3266 bcopy(src, mtod(am, caddr_t), src->sa_len); 3267 if (inp) { 3268 if (in_pcbconnect(inp, am)) { 3269 (void) m_free(am); 3270 goto resetandabort; 3271 } 3272 } 3273 #ifdef INET6 3274 else if (in6p) { 3275 if (src->sa_family == AF_INET) { 3276 /* IPv4 packet to AF_INET6 socket */ 3277 struct sockaddr_in6 *sin6; 3278 sin6 = mtod(am, struct sockaddr_in6 *); 3279 am->m_len = sizeof(*sin6); 3280 bzero(sin6, sizeof(*sin6)); 3281 sin6->sin6_family = AF_INET6; 3282 sin6->sin6_len = sizeof(*sin6); 3283 sin6->sin6_port = ((struct sockaddr_in *)src)->sin_port; 3284 sin6->sin6_addr.s6_addr16[5] = htons(0xffff); 3285 bcopy(&((struct sockaddr_in *)src)->sin_addr, 3286 &sin6->sin6_addr.s6_addr32[3], 3287 sizeof(sin6->sin6_addr.s6_addr32[3])); 3288 } 3289 if (in6_pcbconnect(in6p, am)) { 3290 (void) m_free(am); 3291 goto resetandabort; 3292 } 3293 } 3294 #endif 3295 else { 3296 (void) m_free(am); 3297 goto resetandabort; 3298 } 3299 (void) m_free(am); 3300 3301 if (inp) 3302 tp = intotcpcb(inp); 3303 #ifdef INET6 3304 else if (in6p) 3305 tp = in6totcpcb(in6p); 3306 #endif 3307 else 3308 tp = NULL; 3309 tp->t_flags = sototcpcb(oso)->t_flags & TF_NODELAY; 3310 if (sc->sc_request_r_scale != 15) { 3311 tp->requested_s_scale = sc->sc_requested_s_scale; 3312 tp->request_r_scale = sc->sc_request_r_scale; 3313 tp->snd_scale = sc->sc_requested_s_scale; 3314 tp->rcv_scale = sc->sc_request_r_scale; 3315 tp->t_flags |= TF_REQ_SCALE|TF_RCVD_SCALE; 3316 } 3317 if (sc->sc_flags & SCF_TIMESTAMP) 3318 tp->t_flags |= TF_REQ_TSTMP|TF_RCVD_TSTMP; 3319 tp->ts_timebase = sc->sc_timebase; 3320 3321 tp->t_template = tcp_template(tp); 3322 if (tp->t_template == 0) { 3323 tp = tcp_drop(tp, ENOBUFS); /* destroys socket */ 3324 so = NULL; 3325 m_freem(m); 3326 goto abort; 3327 } 3328 3329 tp->iss = sc->sc_iss; 3330 tp->irs = sc->sc_irs; 3331 tcp_sendseqinit(tp); 3332 tcp_rcvseqinit(tp); 3333 tp->t_state = TCPS_SYN_RECEIVED; 3334 TCP_TIMER_ARM(tp, TCPT_KEEP, TCPTV_KEEP_INIT); 3335 tcpstat.tcps_accepts++; 3336 3337 /* Initialize tp->t_ourmss before we deal with the peer's! */ 3338 tp->t_ourmss = sc->sc_ourmaxseg; 3339 tcp_mss_from_peer(tp, sc->sc_peermaxseg); 3340 3341 /* 3342 * Initialize the initial congestion window. If we 3343 * had to retransmit the SYN,ACK, we must initialize cwnd 3344 * to 1 segment (i.e. the Loss Window). 3345 */ 3346 if (sc->sc_rxtshift) 3347 tp->snd_cwnd = tp->t_peermss; 3348 else { 3349 int ss = tcp_init_win; 3350 #ifdef INET 3351 if (inp != NULL && in_localaddr(inp->inp_faddr)) 3352 ss = tcp_init_win_local; 3353 #endif 3354 #ifdef INET6 3355 if (in6p != NULL && in6_localaddr(&in6p->in6p_faddr)) 3356 ss = tcp_init_win_local; 3357 #endif 3358 tp->snd_cwnd = TCP_INITIAL_WINDOW(ss, tp->t_peermss); 3359 } 3360 3361 tcp_rmx_rtt(tp); 3362 tp->snd_wl1 = sc->sc_irs; 3363 tp->rcv_up = sc->sc_irs + 1; 3364 3365 /* 3366 * This is what whould have happened in tcp_output() when 3367 * the SYN,ACK was sent. 3368 */ 3369 tp->snd_up = tp->snd_una; 3370 tp->snd_max = tp->snd_nxt = tp->iss+1; 3371 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 3372 if (sc->sc_win > 0 && SEQ_GT(tp->rcv_nxt + sc->sc_win, tp->rcv_adv)) 3373 tp->rcv_adv = tp->rcv_nxt + sc->sc_win; 3374 tp->last_ack_sent = tp->rcv_nxt; 3375 3376 tcpstat.tcps_sc_completed++; 3377 SYN_CACHE_PUT(sc); 3378 return (so); 3379 3380 resetandabort: 3381 (void) tcp_respond(NULL, m, m, th, 3382 th->th_seq + tlen, (tcp_seq)0, TH_RST|TH_ACK); 3383 abort: 3384 if (so != NULL) 3385 (void) soabort(so); 3386 SYN_CACHE_PUT(sc); 3387 tcpstat.tcps_sc_aborted++; 3388 return ((struct socket *)(-1)); 3389 } 3390 3391 /* 3392 * This function is called when we get a RST for a 3393 * non-existent connection, so that we can see if the 3394 * connection is in the syn cache. If it is, zap it. 3395 */ 3396 3397 void 3398 syn_cache_reset(src, dst, th) 3399 struct sockaddr *src; 3400 struct sockaddr *dst; 3401 struct tcphdr *th; 3402 { 3403 struct syn_cache *sc; 3404 struct syn_cache_head *scp; 3405 int s = splsoftnet(); 3406 3407 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 3408 splx(s); 3409 return; 3410 } 3411 if (SEQ_LT(th->th_seq, sc->sc_irs) || 3412 SEQ_GT(th->th_seq, sc->sc_irs+1)) { 3413 splx(s); 3414 return; 3415 } 3416 SYN_CACHE_RM(sc); 3417 splx(s); 3418 tcpstat.tcps_sc_reset++; 3419 SYN_CACHE_PUT(sc); 3420 } 3421 3422 void 3423 syn_cache_unreach(src, dst, th) 3424 struct sockaddr *src; 3425 struct sockaddr *dst; 3426 struct tcphdr *th; 3427 { 3428 struct syn_cache *sc; 3429 struct syn_cache_head *scp; 3430 int s; 3431 3432 s = splsoftnet(); 3433 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 3434 splx(s); 3435 return; 3436 } 3437 /* If the sequence number != sc_iss, then it's a bogus ICMP msg */ 3438 if (ntohl (th->th_seq) != sc->sc_iss) { 3439 splx(s); 3440 return; 3441 } 3442 3443 /* 3444 * If we've rertransmitted 3 times and this is our second error, 3445 * we remove the entry. Otherwise, we allow it to continue on. 3446 * This prevents us from incorrectly nuking an entry during a 3447 * spurious network outage. 3448 * 3449 * See tcp_notify(). 3450 */ 3451 if ((sc->sc_flags & SCF_UNREACH) == 0 || sc->sc_rxtshift < 3) { 3452 sc->sc_flags |= SCF_UNREACH; 3453 splx(s); 3454 return; 3455 } 3456 3457 SYN_CACHE_RM(sc); 3458 splx(s); 3459 tcpstat.tcps_sc_unreach++; 3460 SYN_CACHE_PUT(sc); 3461 } 3462 3463 /* 3464 * Given a LISTEN socket and an inbound SYN request, add 3465 * this to the syn cache, and send back a segment: 3466 * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK> 3467 * to the source. 3468 * 3469 * IMPORTANT NOTE: We do _NOT_ ACK data that might accompany the SYN. 3470 * Doing so would require that we hold onto the data and deliver it 3471 * to the application. However, if we are the target of a SYN-flood 3472 * DoS attack, an attacker could send data which would eventually 3473 * consume all available buffer space if it were ACKed. By not ACKing 3474 * the data, we avoid this DoS scenario. 3475 */ 3476 3477 int 3478 syn_cache_add(src, dst, th, hlen, so, m, optp, optlen, oi) 3479 struct sockaddr *src; 3480 struct sockaddr *dst; 3481 struct tcphdr *th; 3482 unsigned int hlen; 3483 struct socket *so; 3484 struct mbuf *m; 3485 u_char *optp; 3486 int optlen; 3487 struct tcp_opt_info *oi; 3488 { 3489 struct tcpcb tb, *tp; 3490 long win; 3491 struct syn_cache *sc; 3492 struct syn_cache_head *scp; 3493 struct mbuf *ipopts; 3494 3495 tp = sototcpcb(so); 3496 3497 /* 3498 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN 3499 * 3500 * Note this check is performed in tcp_input() very early on. 3501 */ 3502 3503 /* 3504 * Initialize some local state. 3505 */ 3506 win = sbspace(&so->so_rcv); 3507 if (win > TCP_MAXWIN) 3508 win = TCP_MAXWIN; 3509 3510 switch (src->sa_family) { 3511 #ifdef INET 3512 case AF_INET: 3513 /* 3514 * Remember the IP options, if any. 3515 */ 3516 ipopts = ip_srcroute(); 3517 break; 3518 #endif 3519 default: 3520 ipopts = NULL; 3521 } 3522 3523 if (optp) { 3524 tb.t_flags = tcp_do_rfc1323 ? (TF_REQ_SCALE|TF_REQ_TSTMP) : 0; 3525 tcp_dooptions(&tb, optp, optlen, th, oi); 3526 } else 3527 tb.t_flags = 0; 3528 3529 /* 3530 * See if we already have an entry for this connection. 3531 * If we do, resend the SYN,ACK. We do not count this 3532 * as a retransmission (XXX though maybe we should). 3533 */ 3534 if ((sc = syn_cache_lookup(src, dst, &scp)) != NULL) { 3535 tcpstat.tcps_sc_dupesyn++; 3536 if (ipopts) { 3537 /* 3538 * If we were remembering a previous source route, 3539 * forget it and use the new one we've been given. 3540 */ 3541 if (sc->sc_ipopts) 3542 (void) m_free(sc->sc_ipopts); 3543 sc->sc_ipopts = ipopts; 3544 } 3545 sc->sc_timestamp = tb.ts_recent; 3546 if (syn_cache_respond(sc, m) == 0) { 3547 tcpstat.tcps_sndacks++; 3548 tcpstat.tcps_sndtotal++; 3549 } 3550 return (1); 3551 } 3552 3553 sc = pool_get(&syn_cache_pool, PR_NOWAIT); 3554 if (sc == NULL) { 3555 if (ipopts) 3556 (void) m_free(ipopts); 3557 return (0); 3558 } 3559 3560 /* 3561 * Fill in the cache, and put the necessary IP and TCP 3562 * options into the reply. 3563 */ 3564 bzero(sc, sizeof(struct syn_cache)); 3565 callout_init(&sc->sc_timer); 3566 bcopy(src, &sc->sc_src, src->sa_len); 3567 bcopy(dst, &sc->sc_dst, dst->sa_len); 3568 sc->sc_flags = 0; 3569 sc->sc_ipopts = ipopts; 3570 sc->sc_irs = th->th_seq; 3571 switch (src->sa_family) { 3572 #ifdef INET 3573 case AF_INET: 3574 { 3575 struct sockaddr_in *srcin = (void *) src; 3576 struct sockaddr_in *dstin = (void *) dst; 3577 3578 sc->sc_iss = tcp_new_iss1(&dstin->sin_addr, 3579 &srcin->sin_addr, dstin->sin_port, 3580 srcin->sin_port, sizeof(dstin->sin_addr), 0); 3581 break; 3582 } 3583 #endif /* INET */ 3584 #ifdef INET6 3585 case AF_INET6: 3586 { 3587 struct sockaddr_in6 *srcin6 = (void *) src; 3588 struct sockaddr_in6 *dstin6 = (void *) dst; 3589 3590 sc->sc_iss = tcp_new_iss1(&dstin6->sin6_addr, 3591 &srcin6->sin6_addr, dstin6->sin6_port, 3592 srcin6->sin6_port, sizeof(dstin6->sin6_addr), 0); 3593 break; 3594 } 3595 #endif /* INET6 */ 3596 } 3597 sc->sc_peermaxseg = oi->maxseg; 3598 sc->sc_ourmaxseg = tcp_mss_to_advertise(m->m_flags & M_PKTHDR ? 3599 m->m_pkthdr.rcvif : NULL, 3600 sc->sc_src.sa.sa_family); 3601 sc->sc_win = win; 3602 sc->sc_timebase = tcp_now; /* see tcp_newtcpcb() */ 3603 sc->sc_timestamp = tb.ts_recent; 3604 if ((tb.t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP)) == 3605 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) 3606 sc->sc_flags |= SCF_TIMESTAMP; 3607 if ((tb.t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 3608 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 3609 sc->sc_requested_s_scale = tb.requested_s_scale; 3610 sc->sc_request_r_scale = 0; 3611 while (sc->sc_request_r_scale < TCP_MAX_WINSHIFT && 3612 TCP_MAXWIN << sc->sc_request_r_scale < 3613 so->so_rcv.sb_hiwat) 3614 sc->sc_request_r_scale++; 3615 } else { 3616 sc->sc_requested_s_scale = 15; 3617 sc->sc_request_r_scale = 15; 3618 } 3619 sc->sc_tp = tp; 3620 if (syn_cache_respond(sc, m) == 0) { 3621 syn_cache_insert(sc, tp); 3622 tcpstat.tcps_sndacks++; 3623 tcpstat.tcps_sndtotal++; 3624 } else { 3625 SYN_CACHE_PUT(sc); 3626 tcpstat.tcps_sc_dropped++; 3627 } 3628 return (1); 3629 } 3630 3631 int 3632 syn_cache_respond(sc, m) 3633 struct syn_cache *sc; 3634 struct mbuf *m; 3635 { 3636 struct route *ro; 3637 u_int8_t *optp; 3638 int optlen, error; 3639 u_int16_t tlen; 3640 struct ip *ip = NULL; 3641 #ifdef INET6 3642 struct ip6_hdr *ip6 = NULL; 3643 #endif 3644 struct tcpcb *tp; 3645 struct tcphdr *th; 3646 u_int hlen; 3647 struct socket *so; 3648 3649 switch (sc->sc_src.sa.sa_family) { 3650 case AF_INET: 3651 hlen = sizeof(struct ip); 3652 ro = &sc->sc_route4; 3653 break; 3654 #ifdef INET6 3655 case AF_INET6: 3656 hlen = sizeof(struct ip6_hdr); 3657 ro = (struct route *)&sc->sc_route6; 3658 break; 3659 #endif 3660 default: 3661 if (m) 3662 m_freem(m); 3663 return EAFNOSUPPORT; 3664 } 3665 3666 /* Compute the size of the TCP options. */ 3667 optlen = 4 + (sc->sc_request_r_scale != 15 ? 4 : 0) + 3668 ((sc->sc_flags & SCF_TIMESTAMP) ? TCPOLEN_TSTAMP_APPA : 0); 3669 3670 tlen = hlen + sizeof(struct tcphdr) + optlen; 3671 3672 /* 3673 * Create the IP+TCP header from scratch. 3674 */ 3675 if (m) 3676 m_freem(m); 3677 #ifdef DIAGNOSTIC 3678 if (max_linkhdr + tlen > MCLBYTES) 3679 return (ENOBUFS); 3680 #endif 3681 MGETHDR(m, M_DONTWAIT, MT_DATA); 3682 if (m && tlen > MHLEN) { 3683 MCLGET(m, M_DONTWAIT); 3684 if ((m->m_flags & M_EXT) == 0) { 3685 m_freem(m); 3686 m = NULL; 3687 } 3688 } 3689 if (m == NULL) 3690 return (ENOBUFS); 3691 MCLAIM(m, &tcp_tx_mowner); 3692 3693 /* Fixup the mbuf. */ 3694 m->m_data += max_linkhdr; 3695 m->m_len = m->m_pkthdr.len = tlen; 3696 if (sc->sc_tp) { 3697 tp = sc->sc_tp; 3698 if (tp->t_inpcb) 3699 so = tp->t_inpcb->inp_socket; 3700 #ifdef INET6 3701 else if (tp->t_in6pcb) 3702 so = tp->t_in6pcb->in6p_socket; 3703 #endif 3704 else 3705 so = NULL; 3706 } else 3707 so = NULL; 3708 m->m_pkthdr.rcvif = NULL; 3709 memset(mtod(m, u_char *), 0, tlen); 3710 3711 switch (sc->sc_src.sa.sa_family) { 3712 case AF_INET: 3713 ip = mtod(m, struct ip *); 3714 ip->ip_dst = sc->sc_src.sin.sin_addr; 3715 ip->ip_src = sc->sc_dst.sin.sin_addr; 3716 ip->ip_p = IPPROTO_TCP; 3717 th = (struct tcphdr *)(ip + 1); 3718 th->th_dport = sc->sc_src.sin.sin_port; 3719 th->th_sport = sc->sc_dst.sin.sin_port; 3720 break; 3721 #ifdef INET6 3722 case AF_INET6: 3723 ip6 = mtod(m, struct ip6_hdr *); 3724 ip6->ip6_dst = sc->sc_src.sin6.sin6_addr; 3725 ip6->ip6_src = sc->sc_dst.sin6.sin6_addr; 3726 ip6->ip6_nxt = IPPROTO_TCP; 3727 /* ip6_plen will be updated in ip6_output() */ 3728 th = (struct tcphdr *)(ip6 + 1); 3729 th->th_dport = sc->sc_src.sin6.sin6_port; 3730 th->th_sport = sc->sc_dst.sin6.sin6_port; 3731 break; 3732 #endif 3733 default: 3734 th = NULL; 3735 } 3736 3737 th->th_seq = htonl(sc->sc_iss); 3738 th->th_ack = htonl(sc->sc_irs + 1); 3739 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 3740 th->th_flags = TH_SYN|TH_ACK; 3741 th->th_win = htons(sc->sc_win); 3742 /* th_sum already 0 */ 3743 /* th_urp already 0 */ 3744 3745 /* Tack on the TCP options. */ 3746 optp = (u_int8_t *)(th + 1); 3747 *optp++ = TCPOPT_MAXSEG; 3748 *optp++ = 4; 3749 *optp++ = (sc->sc_ourmaxseg >> 8) & 0xff; 3750 *optp++ = sc->sc_ourmaxseg & 0xff; 3751 3752 if (sc->sc_request_r_scale != 15) { 3753 *((u_int32_t *)optp) = htonl(TCPOPT_NOP << 24 | 3754 TCPOPT_WINDOW << 16 | TCPOLEN_WINDOW << 8 | 3755 sc->sc_request_r_scale); 3756 optp += 4; 3757 } 3758 3759 if (sc->sc_flags & SCF_TIMESTAMP) { 3760 u_int32_t *lp = (u_int32_t *)(optp); 3761 /* Form timestamp option as shown in appendix A of RFC 1323. */ 3762 *lp++ = htonl(TCPOPT_TSTAMP_HDR); 3763 *lp++ = htonl(SYN_CACHE_TIMESTAMP(sc)); 3764 *lp = htonl(sc->sc_timestamp); 3765 optp += TCPOLEN_TSTAMP_APPA; 3766 } 3767 3768 /* Compute the packet's checksum. */ 3769 switch (sc->sc_src.sa.sa_family) { 3770 case AF_INET: 3771 ip->ip_len = htons(tlen - hlen); 3772 th->th_sum = 0; 3773 th->th_sum = in_cksum(m, tlen); 3774 break; 3775 #ifdef INET6 3776 case AF_INET6: 3777 ip6->ip6_plen = htons(tlen - hlen); 3778 th->th_sum = 0; 3779 th->th_sum = in6_cksum(m, IPPROTO_TCP, hlen, tlen - hlen); 3780 break; 3781 #endif 3782 } 3783 3784 /* 3785 * Fill in some straggling IP bits. Note the stack expects 3786 * ip_len to be in host order, for convenience. 3787 */ 3788 switch (sc->sc_src.sa.sa_family) { 3789 #ifdef INET 3790 case AF_INET: 3791 ip->ip_len = htons(tlen); 3792 ip->ip_ttl = ip_defttl; 3793 /* XXX tos? */ 3794 break; 3795 #endif 3796 #ifdef INET6 3797 case AF_INET6: 3798 ip6->ip6_vfc &= ~IPV6_VERSION_MASK; 3799 ip6->ip6_vfc |= IPV6_VERSION; 3800 ip6->ip6_plen = htons(tlen - hlen); 3801 /* ip6_hlim will be initialized afterwards */ 3802 /* XXX flowlabel? */ 3803 break; 3804 #endif 3805 } 3806 3807 /* XXX use IPsec policy on listening socket, on SYN ACK */ 3808 tp = sc->sc_tp; 3809 3810 switch (sc->sc_src.sa.sa_family) { 3811 #ifdef INET 3812 case AF_INET: 3813 error = ip_output(m, sc->sc_ipopts, ro, 3814 (ip_mtudisc ? IP_MTUDISC : 0), 3815 (struct ip_moptions *)NULL, so); 3816 break; 3817 #endif 3818 #ifdef INET6 3819 case AF_INET6: 3820 ip6->ip6_hlim = in6_selecthlim(NULL, 3821 ro->ro_rt ? ro->ro_rt->rt_ifp : NULL); 3822 3823 error = ip6_output(m, NULL /*XXX*/, (struct route_in6 *)ro, 0, 3824 (struct ip6_moptions *)0, so, NULL); 3825 break; 3826 #endif 3827 default: 3828 error = EAFNOSUPPORT; 3829 break; 3830 } 3831 return (error); 3832 } 3833