1 /* $NetBSD: tcp_input.c,v 1.188 2004/01/02 12:01:39 itojun 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 1.188 2004/01/02 12:01:39 itojun 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 #ifdef INET6 225 #include <netipsec/ipsec6.h> 226 #endif 227 #endif /* FAST_IPSEC*/ 228 229 230 int tcprexmtthresh = 3; 231 int tcp_log_refused; 232 233 static int tcp_rst_ppslim_count = 0; 234 static struct timeval tcp_rst_ppslim_last; 235 236 #define TCP_PAWS_IDLE (24 * 24 * 60 * 60 * PR_SLOWHZ) 237 238 /* for modulo comparisons of timestamps */ 239 #define TSTMP_LT(a,b) ((int)((a)-(b)) < 0) 240 #define TSTMP_GEQ(a,b) ((int)((a)-(b)) >= 0) 241 242 /* 243 * Neighbor Discovery, Neighbor Unreachability Detection Upper layer hint. 244 */ 245 #ifdef INET6 246 #define ND6_HINT(tp) \ 247 do { \ 248 if (tp && tp->t_in6pcb && tp->t_family == AF_INET6 \ 249 && tp->t_in6pcb->in6p_route.ro_rt) { \ 250 nd6_nud_hint(tp->t_in6pcb->in6p_route.ro_rt, NULL, 0); \ 251 } \ 252 } while (/*CONSTCOND*/ 0) 253 #else 254 #define ND6_HINT(tp) 255 #endif 256 257 /* 258 * Macro to compute ACK transmission behavior. Delay the ACK unless 259 * we have already delayed an ACK (must send an ACK every two segments). 260 * We also ACK immediately if we received a PUSH and the ACK-on-PUSH 261 * option is enabled. 262 */ 263 #define TCP_SETUP_ACK(tp, th) \ 264 do { \ 265 if ((tp)->t_flags & TF_DELACK || \ 266 (tcp_ack_on_push && (th)->th_flags & TH_PUSH)) \ 267 tp->t_flags |= TF_ACKNOW; \ 268 else \ 269 TCP_SET_DELACK(tp); \ 270 } while (/*CONSTCOND*/ 0) 271 272 /* 273 * Convert TCP protocol fields to host order for easier processing. 274 */ 275 #define TCP_FIELDS_TO_HOST(th) \ 276 do { \ 277 NTOHL((th)->th_seq); \ 278 NTOHL((th)->th_ack); \ 279 NTOHS((th)->th_win); \ 280 NTOHS((th)->th_urp); \ 281 } while (/*CONSTCOND*/ 0) 282 283 /* 284 * ... and reverse the above. 285 */ 286 #define TCP_FIELDS_TO_NET(th) \ 287 do { \ 288 HTONL((th)->th_seq); \ 289 HTONL((th)->th_ack); \ 290 HTONS((th)->th_win); \ 291 HTONS((th)->th_urp); \ 292 } while (/*CONSTCOND*/ 0) 293 294 #ifdef TCP_CSUM_COUNTERS 295 #include <sys/device.h> 296 297 extern struct evcnt tcp_hwcsum_ok; 298 extern struct evcnt tcp_hwcsum_bad; 299 extern struct evcnt tcp_hwcsum_data; 300 extern struct evcnt tcp_swcsum; 301 302 #define TCP_CSUM_COUNTER_INCR(ev) (ev)->ev_count++ 303 304 #else 305 306 #define TCP_CSUM_COUNTER_INCR(ev) /* nothing */ 307 308 #endif /* TCP_CSUM_COUNTERS */ 309 310 #ifdef TCP_REASS_COUNTERS 311 #include <sys/device.h> 312 313 extern struct evcnt tcp_reass_; 314 extern struct evcnt tcp_reass_empty; 315 extern struct evcnt tcp_reass_iteration[8]; 316 extern struct evcnt tcp_reass_prependfirst; 317 extern struct evcnt tcp_reass_prepend; 318 extern struct evcnt tcp_reass_insert; 319 extern struct evcnt tcp_reass_inserttail; 320 extern struct evcnt tcp_reass_append; 321 extern struct evcnt tcp_reass_appendtail; 322 extern struct evcnt tcp_reass_overlaptail; 323 extern struct evcnt tcp_reass_overlapfront; 324 extern struct evcnt tcp_reass_segdup; 325 extern struct evcnt tcp_reass_fragdup; 326 327 #define TCP_REASS_COUNTER_INCR(ev) (ev)->ev_count++ 328 329 #else 330 331 #define TCP_REASS_COUNTER_INCR(ev) /* nothing */ 332 333 #endif /* TCP_REASS_COUNTERS */ 334 335 #ifdef INET 336 static void tcp4_log_refused __P((const struct ip *, const struct tcphdr *)); 337 #endif 338 #ifdef INET6 339 static void tcp6_log_refused 340 __P((const struct ip6_hdr *, const struct tcphdr *)); 341 #endif 342 343 int 344 tcp_reass(tp, th, m, tlen) 345 struct tcpcb *tp; 346 struct tcphdr *th; 347 struct mbuf *m; 348 int *tlen; 349 { 350 struct ipqent *p, *q, *nq, *tiqe = NULL; 351 struct socket *so = NULL; 352 int pkt_flags; 353 tcp_seq pkt_seq; 354 unsigned pkt_len; 355 u_long rcvpartdupbyte = 0; 356 u_long rcvoobyte; 357 #ifdef TCP_REASS_COUNTERS 358 u_int count = 0; 359 #endif 360 361 if (tp->t_inpcb) 362 so = tp->t_inpcb->inp_socket; 363 #ifdef INET6 364 else if (tp->t_in6pcb) 365 so = tp->t_in6pcb->in6p_socket; 366 #endif 367 368 TCP_REASS_LOCK_CHECK(tp); 369 370 /* 371 * Call with th==0 after become established to 372 * force pre-ESTABLISHED data up to user socket. 373 */ 374 if (th == 0) 375 goto present; 376 377 rcvoobyte = *tlen; 378 /* 379 * Copy these to local variables because the tcpiphdr 380 * gets munged while we are collapsing mbufs. 381 */ 382 pkt_seq = th->th_seq; 383 pkt_len = *tlen; 384 pkt_flags = th->th_flags; 385 386 TCP_REASS_COUNTER_INCR(&tcp_reass_); 387 388 if ((p = TAILQ_LAST(&tp->segq, ipqehead)) != NULL) { 389 /* 390 * When we miss a packet, the vast majority of time we get 391 * packets that follow it in order. So optimize for that. 392 */ 393 if (pkt_seq == p->ipqe_seq + p->ipqe_len) { 394 p->ipqe_len += pkt_len; 395 p->ipqe_flags |= pkt_flags; 396 m_cat(p->ipqe_m, m); 397 tiqe = p; 398 TAILQ_REMOVE(&tp->timeq, p, ipqe_timeq); 399 TCP_REASS_COUNTER_INCR(&tcp_reass_appendtail); 400 goto skip_replacement; 401 } 402 /* 403 * While we're here, if the pkt is completely beyond 404 * anything we have, just insert it at the tail. 405 */ 406 if (SEQ_GT(pkt_seq, p->ipqe_seq + p->ipqe_len)) { 407 TCP_REASS_COUNTER_INCR(&tcp_reass_inserttail); 408 goto insert_it; 409 } 410 } 411 412 q = TAILQ_FIRST(&tp->segq); 413 414 if (q != NULL) { 415 /* 416 * If this segment immediately precedes the first out-of-order 417 * block, simply slap the segment in front of it and (mostly) 418 * skip the complicated logic. 419 */ 420 if (pkt_seq + pkt_len == q->ipqe_seq) { 421 q->ipqe_seq = pkt_seq; 422 q->ipqe_len += pkt_len; 423 q->ipqe_flags |= pkt_flags; 424 m_cat(m, q->ipqe_m); 425 q->ipqe_m = m; 426 tiqe = q; 427 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 428 TCP_REASS_COUNTER_INCR(&tcp_reass_prependfirst); 429 goto skip_replacement; 430 } 431 } else { 432 TCP_REASS_COUNTER_INCR(&tcp_reass_empty); 433 } 434 435 /* 436 * Find a segment which begins after this one does. 437 */ 438 for (p = NULL; q != NULL; q = nq) { 439 nq = TAILQ_NEXT(q, ipqe_q); 440 #ifdef TCP_REASS_COUNTERS 441 count++; 442 #endif 443 /* 444 * If the received segment is just right after this 445 * fragment, merge the two together and then check 446 * for further overlaps. 447 */ 448 if (q->ipqe_seq + q->ipqe_len == pkt_seq) { 449 #ifdef TCPREASS_DEBUG 450 printf("tcp_reass[%p]: concat %u:%u(%u) to %u:%u(%u)\n", 451 tp, pkt_seq, pkt_seq + pkt_len, pkt_len, 452 q->ipqe_seq, q->ipqe_seq + q->ipqe_len, q->ipqe_len); 453 #endif 454 pkt_len += q->ipqe_len; 455 pkt_flags |= q->ipqe_flags; 456 pkt_seq = q->ipqe_seq; 457 m_cat(q->ipqe_m, m); 458 m = q->ipqe_m; 459 TCP_REASS_COUNTER_INCR(&tcp_reass_append); 460 goto free_ipqe; 461 } 462 /* 463 * If the received segment is completely past this 464 * fragment, we need to go the next fragment. 465 */ 466 if (SEQ_LT(q->ipqe_seq + q->ipqe_len, pkt_seq)) { 467 p = q; 468 continue; 469 } 470 /* 471 * If the fragment is past the received segment, 472 * it (or any following) can't be concatenated. 473 */ 474 if (SEQ_GT(q->ipqe_seq, pkt_seq + pkt_len)) { 475 TCP_REASS_COUNTER_INCR(&tcp_reass_insert); 476 break; 477 } 478 479 /* 480 * We've received all the data in this segment before. 481 * mark it as a duplicate and return. 482 */ 483 if (SEQ_LEQ(q->ipqe_seq, pkt_seq) && 484 SEQ_GEQ(q->ipqe_seq + q->ipqe_len, pkt_seq + pkt_len)) { 485 tcpstat.tcps_rcvduppack++; 486 tcpstat.tcps_rcvdupbyte += pkt_len; 487 m_freem(m); 488 if (tiqe != NULL) 489 pool_put(&ipqent_pool, tiqe); 490 TCP_REASS_COUNTER_INCR(&tcp_reass_segdup); 491 return (0); 492 } 493 /* 494 * Received segment completely overlaps this fragment 495 * so we drop the fragment (this keeps the temporal 496 * ordering of segments correct). 497 */ 498 if (SEQ_GEQ(q->ipqe_seq, pkt_seq) && 499 SEQ_LEQ(q->ipqe_seq + q->ipqe_len, pkt_seq + pkt_len)) { 500 rcvpartdupbyte += q->ipqe_len; 501 m_freem(q->ipqe_m); 502 TCP_REASS_COUNTER_INCR(&tcp_reass_fragdup); 503 goto free_ipqe; 504 } 505 /* 506 * RX'ed segment extends past the end of the 507 * fragment. Drop the overlapping bytes. Then 508 * merge the fragment and segment then treat as 509 * a longer received packet. 510 */ 511 if (SEQ_LT(q->ipqe_seq, pkt_seq) 512 && SEQ_GT(q->ipqe_seq + q->ipqe_len, pkt_seq)) { 513 int overlap = q->ipqe_seq + q->ipqe_len - pkt_seq; 514 #ifdef TCPREASS_DEBUG 515 printf("tcp_reass[%p]: trim starting %d bytes of %u:%u(%u)\n", 516 tp, overlap, 517 pkt_seq, pkt_seq + pkt_len, pkt_len); 518 #endif 519 m_adj(m, overlap); 520 rcvpartdupbyte += overlap; 521 m_cat(q->ipqe_m, m); 522 m = q->ipqe_m; 523 pkt_seq = q->ipqe_seq; 524 pkt_len += q->ipqe_len - overlap; 525 rcvoobyte -= overlap; 526 TCP_REASS_COUNTER_INCR(&tcp_reass_overlaptail); 527 goto free_ipqe; 528 } 529 /* 530 * RX'ed segment extends past the front of the 531 * fragment. Drop the overlapping bytes on the 532 * received packet. The packet will then be 533 * contatentated with this fragment a bit later. 534 */ 535 if (SEQ_GT(q->ipqe_seq, pkt_seq) 536 && SEQ_LT(q->ipqe_seq, pkt_seq + pkt_len)) { 537 int overlap = pkt_seq + pkt_len - q->ipqe_seq; 538 #ifdef TCPREASS_DEBUG 539 printf("tcp_reass[%p]: trim trailing %d bytes of %u:%u(%u)\n", 540 tp, overlap, 541 pkt_seq, pkt_seq + pkt_len, pkt_len); 542 #endif 543 m_adj(m, -overlap); 544 pkt_len -= overlap; 545 rcvpartdupbyte += overlap; 546 TCP_REASS_COUNTER_INCR(&tcp_reass_overlapfront); 547 rcvoobyte -= overlap; 548 } 549 /* 550 * If the received segment immediates precedes this 551 * fragment then tack the fragment onto this segment 552 * and reinsert the data. 553 */ 554 if (q->ipqe_seq == pkt_seq + pkt_len) { 555 #ifdef TCPREASS_DEBUG 556 printf("tcp_reass[%p]: append %u:%u(%u) to %u:%u(%u)\n", 557 tp, q->ipqe_seq, q->ipqe_seq + q->ipqe_len, q->ipqe_len, 558 pkt_seq, pkt_seq + pkt_len, pkt_len); 559 #endif 560 pkt_len += q->ipqe_len; 561 pkt_flags |= q->ipqe_flags; 562 m_cat(m, q->ipqe_m); 563 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 564 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 565 if (tiqe == NULL) { 566 tiqe = q; 567 } else { 568 pool_put(&ipqent_pool, q); 569 } 570 TCP_REASS_COUNTER_INCR(&tcp_reass_prepend); 571 break; 572 } 573 /* 574 * If the fragment is before the segment, remember it. 575 * When this loop is terminated, p will contain the 576 * pointer to fragment that is right before the received 577 * segment. 578 */ 579 if (SEQ_LEQ(q->ipqe_seq, pkt_seq)) 580 p = q; 581 582 continue; 583 584 /* 585 * This is a common operation. It also will allow 586 * to save doing a malloc/free in most instances. 587 */ 588 free_ipqe: 589 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 590 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 591 if (tiqe == NULL) { 592 tiqe = q; 593 } else { 594 pool_put(&ipqent_pool, q); 595 } 596 } 597 598 #ifdef TCP_REASS_COUNTERS 599 if (count > 7) 600 TCP_REASS_COUNTER_INCR(&tcp_reass_iteration[0]); 601 else if (count > 0) 602 TCP_REASS_COUNTER_INCR(&tcp_reass_iteration[count]); 603 #endif 604 605 insert_it: 606 607 /* 608 * Allocate a new queue entry since the received segment did not 609 * collapse onto any other out-of-order block; thus we are allocating 610 * a new block. If it had collapsed, tiqe would not be NULL and 611 * we would be reusing it. 612 * XXX If we can't, just drop the packet. XXX 613 */ 614 if (tiqe == NULL) { 615 tiqe = pool_get(&ipqent_pool, PR_NOWAIT); 616 if (tiqe == NULL) { 617 tcpstat.tcps_rcvmemdrop++; 618 m_freem(m); 619 return (0); 620 } 621 } 622 623 /* 624 * Update the counters. 625 */ 626 tcpstat.tcps_rcvoopack++; 627 tcpstat.tcps_rcvoobyte += rcvoobyte; 628 if (rcvpartdupbyte) { 629 tcpstat.tcps_rcvpartduppack++; 630 tcpstat.tcps_rcvpartdupbyte += rcvpartdupbyte; 631 } 632 633 /* 634 * Insert the new fragment queue entry into both queues. 635 */ 636 tiqe->ipqe_m = m; 637 tiqe->ipqe_seq = pkt_seq; 638 tiqe->ipqe_len = pkt_len; 639 tiqe->ipqe_flags = pkt_flags; 640 if (p == NULL) { 641 TAILQ_INSERT_HEAD(&tp->segq, tiqe, ipqe_q); 642 #ifdef TCPREASS_DEBUG 643 if (tiqe->ipqe_seq != tp->rcv_nxt) 644 printf("tcp_reass[%p]: insert %u:%u(%u) at front\n", 645 tp, pkt_seq, pkt_seq + pkt_len, pkt_len); 646 #endif 647 } else { 648 TAILQ_INSERT_AFTER(&tp->segq, p, tiqe, ipqe_q); 649 #ifdef TCPREASS_DEBUG 650 printf("tcp_reass[%p]: insert %u:%u(%u) after %u:%u(%u)\n", 651 tp, pkt_seq, pkt_seq + pkt_len, pkt_len, 652 p->ipqe_seq, p->ipqe_seq + p->ipqe_len, p->ipqe_len); 653 #endif 654 } 655 656 skip_replacement: 657 658 TAILQ_INSERT_HEAD(&tp->timeq, tiqe, ipqe_timeq); 659 660 present: 661 /* 662 * Present data to user, advancing rcv_nxt through 663 * completed sequence space. 664 */ 665 if (TCPS_HAVEESTABLISHED(tp->t_state) == 0) 666 return (0); 667 q = TAILQ_FIRST(&tp->segq); 668 if (q == NULL || q->ipqe_seq != tp->rcv_nxt) 669 return (0); 670 if (tp->t_state == TCPS_SYN_RECEIVED && q->ipqe_len) 671 return (0); 672 673 tp->rcv_nxt += q->ipqe_len; 674 pkt_flags = q->ipqe_flags & TH_FIN; 675 ND6_HINT(tp); 676 677 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 678 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 679 if (so->so_state & SS_CANTRCVMORE) 680 m_freem(q->ipqe_m); 681 else 682 sbappendstream(&so->so_rcv, q->ipqe_m); 683 pool_put(&ipqent_pool, q); 684 sorwakeup(so); 685 return (pkt_flags); 686 } 687 688 #ifdef INET6 689 int 690 tcp6_input(mp, offp, proto) 691 struct mbuf **mp; 692 int *offp, proto; 693 { 694 struct mbuf *m = *mp; 695 696 /* 697 * draft-itojun-ipv6-tcp-to-anycast 698 * better place to put this in? 699 */ 700 if (m->m_flags & M_ANYCAST6) { 701 struct ip6_hdr *ip6; 702 if (m->m_len < sizeof(struct ip6_hdr)) { 703 if ((m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) { 704 tcpstat.tcps_rcvshort++; 705 return IPPROTO_DONE; 706 } 707 } 708 ip6 = mtod(m, struct ip6_hdr *); 709 icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR, 710 (caddr_t)&ip6->ip6_dst - (caddr_t)ip6); 711 return IPPROTO_DONE; 712 } 713 714 tcp_input(m, *offp, proto); 715 return IPPROTO_DONE; 716 } 717 #endif 718 719 #ifdef INET 720 static void 721 tcp4_log_refused(ip, th) 722 const struct ip *ip; 723 const struct tcphdr *th; 724 { 725 char src[4*sizeof "123"]; 726 char dst[4*sizeof "123"]; 727 728 if (ip) { 729 strlcpy(src, inet_ntoa(ip->ip_src), sizeof(src)); 730 strlcpy(dst, inet_ntoa(ip->ip_dst), sizeof(dst)); 731 } 732 else { 733 strlcpy(src, "(unknown)", sizeof(src)); 734 strlcpy(dst, "(unknown)", sizeof(dst)); 735 } 736 log(LOG_INFO, 737 "Connection attempt to TCP %s:%d from %s:%d\n", 738 dst, ntohs(th->th_dport), 739 src, ntohs(th->th_sport)); 740 } 741 #endif 742 743 #ifdef INET6 744 static void 745 tcp6_log_refused(ip6, th) 746 const struct ip6_hdr *ip6; 747 const struct tcphdr *th; 748 { 749 char src[INET6_ADDRSTRLEN]; 750 char dst[INET6_ADDRSTRLEN]; 751 752 if (ip6) { 753 strlcpy(src, ip6_sprintf(&ip6->ip6_src), sizeof(src)); 754 strlcpy(dst, ip6_sprintf(&ip6->ip6_dst), sizeof(dst)); 755 } 756 else { 757 strlcpy(src, "(unknown v6)", sizeof(src)); 758 strlcpy(dst, "(unknown v6)", sizeof(dst)); 759 } 760 log(LOG_INFO, 761 "Connection attempt to TCP [%s]:%d from [%s]:%d\n", 762 dst, ntohs(th->th_dport), 763 src, ntohs(th->th_sport)); 764 } 765 #endif 766 767 /* 768 * TCP input routine, follows pages 65-76 of the 769 * protocol specification dated September, 1981 very closely. 770 */ 771 void 772 #if __STDC__ 773 tcp_input(struct mbuf *m, ...) 774 #else 775 tcp_input(m, va_alist) 776 struct mbuf *m; 777 #endif 778 { 779 struct tcphdr *th; 780 struct ip *ip; 781 struct inpcb *inp; 782 #ifdef INET6 783 struct ip6_hdr *ip6; 784 struct in6pcb *in6p; 785 #endif 786 u_int8_t *optp = NULL; 787 int optlen = 0; 788 int len, tlen, toff, hdroptlen = 0; 789 struct tcpcb *tp = 0; 790 int tiflags; 791 struct socket *so = NULL; 792 int todrop, acked, ourfinisacked, needoutput = 0; 793 #ifdef TCP_DEBUG 794 short ostate = 0; 795 #endif 796 int iss = 0; 797 u_long tiwin; 798 struct tcp_opt_info opti; 799 int off, iphlen; 800 va_list ap; 801 int af; /* af on the wire */ 802 struct mbuf *tcp_saveti = NULL; 803 804 MCLAIM(m, &tcp_rx_mowner); 805 va_start(ap, m); 806 toff = va_arg(ap, int); 807 (void)va_arg(ap, int); /* ignore value, advance ap */ 808 va_end(ap); 809 810 tcpstat.tcps_rcvtotal++; 811 812 bzero(&opti, sizeof(opti)); 813 opti.ts_present = 0; 814 opti.maxseg = 0; 815 816 /* 817 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN. 818 * 819 * TCP is, by definition, unicast, so we reject all 820 * multicast outright. 821 * 822 * Note, there are additional src/dst address checks in 823 * the AF-specific code below. 824 */ 825 if (m->m_flags & (M_BCAST|M_MCAST)) { 826 /* XXX stat */ 827 goto drop; 828 } 829 #ifdef INET6 830 if (m->m_flags & M_ANYCAST6) { 831 /* XXX stat */ 832 goto drop; 833 } 834 #endif 835 836 /* 837 * Get IP and TCP header together in first mbuf. 838 * Note: IP leaves IP header in first mbuf. 839 */ 840 ip = mtod(m, struct ip *); 841 #ifdef INET6 842 ip6 = NULL; 843 #endif 844 switch (ip->ip_v) { 845 #ifdef INET 846 case 4: 847 af = AF_INET; 848 iphlen = sizeof(struct ip); 849 ip = mtod(m, struct ip *); 850 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, 851 sizeof(struct tcphdr)); 852 if (th == NULL) { 853 tcpstat.tcps_rcvshort++; 854 return; 855 } 856 /* We do the checksum after PCB lookup... */ 857 len = ntohs(ip->ip_len); 858 tlen = len - toff; 859 break; 860 #endif 861 #ifdef INET6 862 case 6: 863 ip = NULL; 864 iphlen = sizeof(struct ip6_hdr); 865 af = AF_INET6; 866 ip6 = mtod(m, struct ip6_hdr *); 867 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, 868 sizeof(struct tcphdr)); 869 if (th == NULL) { 870 tcpstat.tcps_rcvshort++; 871 return; 872 } 873 874 /* Be proactive about malicious use of IPv4 mapped address */ 875 if (IN6_IS_ADDR_V4MAPPED(&ip6->ip6_src) || 876 IN6_IS_ADDR_V4MAPPED(&ip6->ip6_dst)) { 877 /* XXX stat */ 878 goto drop; 879 } 880 881 /* 882 * Be proactive about unspecified IPv6 address in source. 883 * As we use all-zero to indicate unbounded/unconnected pcb, 884 * unspecified IPv6 address can be used to confuse us. 885 * 886 * Note that packets with unspecified IPv6 destination is 887 * already dropped in ip6_input. 888 */ 889 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 890 /* XXX stat */ 891 goto drop; 892 } 893 894 /* 895 * Make sure destination address is not multicast. 896 * Source address checked in ip6_input(). 897 */ 898 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) { 899 /* XXX stat */ 900 goto drop; 901 } 902 903 /* We do the checksum after PCB lookup... */ 904 len = m->m_pkthdr.len; 905 tlen = len - toff; 906 break; 907 #endif 908 default: 909 m_freem(m); 910 return; 911 } 912 913 KASSERT(TCP_HDR_ALIGNED_P(th)); 914 915 /* 916 * Check that TCP offset makes sense, 917 * pull out TCP options and adjust length. XXX 918 */ 919 off = th->th_off << 2; 920 if (off < sizeof (struct tcphdr) || off > tlen) { 921 tcpstat.tcps_rcvbadoff++; 922 goto drop; 923 } 924 tlen -= off; 925 926 /* 927 * tcp_input() has been modified to use tlen to mean the TCP data 928 * length throughout the function. Other functions can use 929 * m->m_pkthdr.len as the basis for calculating the TCP data length. 930 * rja 931 */ 932 933 if (off > sizeof (struct tcphdr)) { 934 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, off); 935 if (th == NULL) { 936 tcpstat.tcps_rcvshort++; 937 return; 938 } 939 /* 940 * NOTE: ip/ip6 will not be affected by m_pulldown() 941 * (as they're before toff) and we don't need to update those. 942 */ 943 KASSERT(TCP_HDR_ALIGNED_P(th)); 944 optlen = off - sizeof (struct tcphdr); 945 optp = ((u_int8_t *)th) + sizeof(struct tcphdr); 946 /* 947 * Do quick retrieval of timestamp options ("options 948 * prediction?"). If timestamp is the only option and it's 949 * formatted as recommended in RFC 1323 appendix A, we 950 * quickly get the values now and not bother calling 951 * tcp_dooptions(), etc. 952 */ 953 if ((optlen == TCPOLEN_TSTAMP_APPA || 954 (optlen > TCPOLEN_TSTAMP_APPA && 955 optp[TCPOLEN_TSTAMP_APPA] == TCPOPT_EOL)) && 956 *(u_int32_t *)optp == htonl(TCPOPT_TSTAMP_HDR) && 957 (th->th_flags & TH_SYN) == 0) { 958 opti.ts_present = 1; 959 opti.ts_val = ntohl(*(u_int32_t *)(optp + 4)); 960 opti.ts_ecr = ntohl(*(u_int32_t *)(optp + 8)); 961 optp = NULL; /* we've parsed the options */ 962 } 963 } 964 tiflags = th->th_flags; 965 966 /* 967 * Locate pcb for segment. 968 */ 969 findpcb: 970 inp = NULL; 971 #ifdef INET6 972 in6p = NULL; 973 #endif 974 switch (af) { 975 #ifdef INET 976 case AF_INET: 977 inp = in_pcblookup_connect(&tcbtable, ip->ip_src, th->th_sport, 978 ip->ip_dst, th->th_dport); 979 if (inp == 0) { 980 ++tcpstat.tcps_pcbhashmiss; 981 inp = in_pcblookup_bind(&tcbtable, ip->ip_dst, th->th_dport); 982 } 983 #ifdef INET6 984 if (inp == 0) { 985 struct in6_addr s, d; 986 987 /* mapped addr case */ 988 bzero(&s, sizeof(s)); 989 s.s6_addr16[5] = htons(0xffff); 990 bcopy(&ip->ip_src, &s.s6_addr32[3], sizeof(ip->ip_src)); 991 bzero(&d, sizeof(d)); 992 d.s6_addr16[5] = htons(0xffff); 993 bcopy(&ip->ip_dst, &d.s6_addr32[3], sizeof(ip->ip_dst)); 994 in6p = in6_pcblookup_connect(&tcbtable, &s, 995 th->th_sport, &d, th->th_dport, 0); 996 if (in6p == 0) { 997 ++tcpstat.tcps_pcbhashmiss; 998 in6p = in6_pcblookup_bind(&tcbtable, &d, 999 th->th_dport, 0); 1000 } 1001 } 1002 #endif 1003 #ifndef INET6 1004 if (inp == 0) 1005 #else 1006 if (inp == 0 && in6p == 0) 1007 #endif 1008 { 1009 ++tcpstat.tcps_noport; 1010 if (tcp_log_refused && 1011 (tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) { 1012 tcp4_log_refused(ip, th); 1013 } 1014 TCP_FIELDS_TO_HOST(th); 1015 goto dropwithreset_ratelim; 1016 } 1017 #if defined(IPSEC) || defined(FAST_IPSEC) 1018 if (inp && (inp->inp_socket->so_options & SO_ACCEPTCONN) == 0 && 1019 ipsec4_in_reject(m, inp)) { 1020 ipsecstat.in_polvio++; 1021 goto drop; 1022 } 1023 #ifdef INET6 1024 else if (in6p && 1025 (in6p->in6p_socket->so_options & SO_ACCEPTCONN) == 0 && 1026 ipsec4_in_reject_so(m, in6p->in6p_socket)) { 1027 ipsecstat.in_polvio++; 1028 goto drop; 1029 } 1030 #endif 1031 #endif /*IPSEC*/ 1032 break; 1033 #endif /*INET*/ 1034 #ifdef INET6 1035 case AF_INET6: 1036 { 1037 int faith; 1038 1039 #if defined(NFAITH) && NFAITH > 0 1040 faith = faithprefix(&ip6->ip6_dst); 1041 #else 1042 faith = 0; 1043 #endif 1044 in6p = in6_pcblookup_connect(&tcbtable, &ip6->ip6_src, 1045 th->th_sport, &ip6->ip6_dst, th->th_dport, faith); 1046 if (in6p == NULL) { 1047 ++tcpstat.tcps_pcbhashmiss; 1048 in6p = in6_pcblookup_bind(&tcbtable, &ip6->ip6_dst, 1049 th->th_dport, faith); 1050 } 1051 if (in6p == NULL) { 1052 ++tcpstat.tcps_noport; 1053 if (tcp_log_refused && 1054 (tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) { 1055 tcp6_log_refused(ip6, th); 1056 } 1057 TCP_FIELDS_TO_HOST(th); 1058 goto dropwithreset_ratelim; 1059 } 1060 #if defined(IPSEC) || defined(FAST_IPSEC) 1061 if ((in6p->in6p_socket->so_options & SO_ACCEPTCONN) == 0 && 1062 ipsec6_in_reject(m, in6p)) { 1063 ipsec6stat.in_polvio++; 1064 goto drop; 1065 } 1066 #endif /*IPSEC*/ 1067 break; 1068 } 1069 #endif 1070 } 1071 1072 /* 1073 * If the state is CLOSED (i.e., TCB does not exist) then 1074 * all data in the incoming segment is discarded. 1075 * If the TCB exists but is in CLOSED state, it is embryonic, 1076 * but should either do a listen or a connect soon. 1077 */ 1078 tp = NULL; 1079 so = NULL; 1080 if (inp) { 1081 tp = intotcpcb(inp); 1082 so = inp->inp_socket; 1083 } 1084 #ifdef INET6 1085 else if (in6p) { 1086 tp = in6totcpcb(in6p); 1087 so = in6p->in6p_socket; 1088 } 1089 #endif 1090 if (tp == 0) { 1091 TCP_FIELDS_TO_HOST(th); 1092 goto dropwithreset_ratelim; 1093 } 1094 if (tp->t_state == TCPS_CLOSED) 1095 goto drop; 1096 1097 /* 1098 * Checksum extended TCP header and data. 1099 */ 1100 switch (af) { 1101 #ifdef INET 1102 case AF_INET: 1103 switch (m->m_pkthdr.csum_flags & 1104 ((m->m_pkthdr.rcvif->if_csum_flags_rx & M_CSUM_TCPv4) | 1105 M_CSUM_TCP_UDP_BAD | M_CSUM_DATA)) { 1106 case M_CSUM_TCPv4|M_CSUM_TCP_UDP_BAD: 1107 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_bad); 1108 goto badcsum; 1109 1110 case M_CSUM_TCPv4|M_CSUM_DATA: { 1111 u_int32_t hw_csum = m->m_pkthdr.csum_data; 1112 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_data); 1113 if (m->m_pkthdr.csum_flags & M_CSUM_NO_PSEUDOHDR) { 1114 hw_csum = in_cksum_phdr(ip->ip_src.s_addr, 1115 ip->ip_dst.s_addr, 1116 htonl(hw_csum + ntohs(ip->ip_len) + 1117 IPPROTO_UDP)); 1118 } 1119 if ((hw_csum ^ 0xffff) != 0) 1120 goto badcsum; 1121 break; 1122 } 1123 1124 case M_CSUM_TCPv4: 1125 /* Checksum was okay. */ 1126 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_ok); 1127 break; 1128 1129 default: 1130 /* Must compute it ourselves. */ 1131 TCP_CSUM_COUNTER_INCR(&tcp_swcsum); 1132 if (in4_cksum(m, IPPROTO_TCP, toff, tlen + off) != 0) 1133 goto badcsum; 1134 break; 1135 } 1136 break; 1137 #endif /* INET4 */ 1138 1139 #ifdef INET6 1140 case AF_INET6: 1141 if (in6_cksum(m, IPPROTO_TCP, toff, tlen + off) != 0) 1142 goto badcsum; 1143 break; 1144 #endif /* INET6 */ 1145 } 1146 1147 TCP_FIELDS_TO_HOST(th); 1148 1149 /* Unscale the window into a 32-bit value. */ 1150 if ((tiflags & TH_SYN) == 0) 1151 tiwin = th->th_win << tp->snd_scale; 1152 else 1153 tiwin = th->th_win; 1154 1155 #ifdef INET6 1156 /* save packet options if user wanted */ 1157 if (in6p && (in6p->in6p_flags & IN6P_CONTROLOPTS)) { 1158 if (in6p->in6p_options) { 1159 m_freem(in6p->in6p_options); 1160 in6p->in6p_options = 0; 1161 } 1162 ip6_savecontrol(in6p, &in6p->in6p_options, ip6, m); 1163 } 1164 #endif 1165 1166 if (so->so_options & (SO_DEBUG|SO_ACCEPTCONN)) { 1167 union syn_cache_sa src; 1168 union syn_cache_sa dst; 1169 1170 bzero(&src, sizeof(src)); 1171 bzero(&dst, sizeof(dst)); 1172 switch (af) { 1173 #ifdef INET 1174 case AF_INET: 1175 src.sin.sin_len = sizeof(struct sockaddr_in); 1176 src.sin.sin_family = AF_INET; 1177 src.sin.sin_addr = ip->ip_src; 1178 src.sin.sin_port = th->th_sport; 1179 1180 dst.sin.sin_len = sizeof(struct sockaddr_in); 1181 dst.sin.sin_family = AF_INET; 1182 dst.sin.sin_addr = ip->ip_dst; 1183 dst.sin.sin_port = th->th_dport; 1184 break; 1185 #endif 1186 #ifdef INET6 1187 case AF_INET6: 1188 src.sin6.sin6_len = sizeof(struct sockaddr_in6); 1189 src.sin6.sin6_family = AF_INET6; 1190 src.sin6.sin6_addr = ip6->ip6_src; 1191 src.sin6.sin6_port = th->th_sport; 1192 1193 dst.sin6.sin6_len = sizeof(struct sockaddr_in6); 1194 dst.sin6.sin6_family = AF_INET6; 1195 dst.sin6.sin6_addr = ip6->ip6_dst; 1196 dst.sin6.sin6_port = th->th_dport; 1197 break; 1198 #endif /* INET6 */ 1199 default: 1200 goto badsyn; /*sanity*/ 1201 } 1202 1203 if (so->so_options & SO_DEBUG) { 1204 #ifdef TCP_DEBUG 1205 ostate = tp->t_state; 1206 #endif 1207 1208 tcp_saveti = NULL; 1209 if (iphlen + sizeof(struct tcphdr) > MHLEN) 1210 goto nosave; 1211 1212 if (m->m_len > iphlen && (m->m_flags & M_EXT) == 0) { 1213 tcp_saveti = m_copym(m, 0, iphlen, M_DONTWAIT); 1214 if (!tcp_saveti) 1215 goto nosave; 1216 } else { 1217 MGETHDR(tcp_saveti, M_DONTWAIT, MT_HEADER); 1218 if (!tcp_saveti) 1219 goto nosave; 1220 MCLAIM(m, &tcp_mowner); 1221 tcp_saveti->m_len = iphlen; 1222 m_copydata(m, 0, iphlen, 1223 mtod(tcp_saveti, caddr_t)); 1224 } 1225 1226 if (M_TRAILINGSPACE(tcp_saveti) < sizeof(struct tcphdr)) { 1227 m_freem(tcp_saveti); 1228 tcp_saveti = NULL; 1229 } else { 1230 tcp_saveti->m_len += sizeof(struct tcphdr); 1231 bcopy(th, mtod(tcp_saveti, caddr_t) + iphlen, 1232 sizeof(struct tcphdr)); 1233 } 1234 nosave:; 1235 } 1236 if (so->so_options & SO_ACCEPTCONN) { 1237 if ((tiflags & (TH_RST|TH_ACK|TH_SYN)) != TH_SYN) { 1238 if (tiflags & TH_RST) { 1239 syn_cache_reset(&src.sa, &dst.sa, th); 1240 } else if ((tiflags & (TH_ACK|TH_SYN)) == 1241 (TH_ACK|TH_SYN)) { 1242 /* 1243 * Received a SYN,ACK. This should 1244 * never happen while we are in 1245 * LISTEN. Send an RST. 1246 */ 1247 goto badsyn; 1248 } else if (tiflags & TH_ACK) { 1249 so = syn_cache_get(&src.sa, &dst.sa, 1250 th, toff, tlen, so, m); 1251 if (so == NULL) { 1252 /* 1253 * We don't have a SYN for 1254 * this ACK; send an RST. 1255 */ 1256 goto badsyn; 1257 } else if (so == 1258 (struct socket *)(-1)) { 1259 /* 1260 * We were unable to create 1261 * the connection. If the 1262 * 3-way handshake was 1263 * completed, and RST has 1264 * been sent to the peer. 1265 * Since the mbuf might be 1266 * in use for the reply, 1267 * do not free it. 1268 */ 1269 m = NULL; 1270 } else { 1271 /* 1272 * We have created a 1273 * full-blown connection. 1274 */ 1275 tp = NULL; 1276 inp = NULL; 1277 #ifdef INET6 1278 in6p = NULL; 1279 #endif 1280 switch (so->so_proto->pr_domain->dom_family) { 1281 #ifdef INET 1282 case AF_INET: 1283 inp = sotoinpcb(so); 1284 tp = intotcpcb(inp); 1285 break; 1286 #endif 1287 #ifdef INET6 1288 case AF_INET6: 1289 in6p = sotoin6pcb(so); 1290 tp = in6totcpcb(in6p); 1291 break; 1292 #endif 1293 } 1294 if (tp == NULL) 1295 goto badsyn; /*XXX*/ 1296 tiwin <<= tp->snd_scale; 1297 goto after_listen; 1298 } 1299 } else { 1300 /* 1301 * None of RST, SYN or ACK was set. 1302 * This is an invalid packet for a 1303 * TCB in LISTEN state. Send a RST. 1304 */ 1305 goto badsyn; 1306 } 1307 } else { 1308 /* 1309 * Received a SYN. 1310 */ 1311 1312 #ifdef INET6 1313 /* 1314 * If deprecated address is forbidden, we do 1315 * not accept SYN to deprecated interface 1316 * address to prevent any new inbound 1317 * connection from getting established. 1318 * When we do not accept SYN, we send a TCP 1319 * RST, with deprecated source address (instead 1320 * of dropping it). We compromise it as it is 1321 * much better for peer to send a RST, and 1322 * RST will be the final packet for the 1323 * exchange. 1324 * 1325 * If we do not forbid deprecated addresses, we 1326 * accept the SYN packet. RFC2462 does not 1327 * suggest dropping SYN in this case. 1328 * If we decipher RFC2462 5.5.4, it says like 1329 * this: 1330 * 1. use of deprecated addr with existing 1331 * communication is okay - "SHOULD continue 1332 * to be used" 1333 * 2. use of it with new communication: 1334 * (2a) "SHOULD NOT be used if alternate 1335 * address with sufficient scope is 1336 * available" 1337 * (2b) nothing mentioned otherwise. 1338 * Here we fall into (2b) case as we have no 1339 * choice in our source address selection - we 1340 * must obey the peer. 1341 * 1342 * The wording in RFC2462 is confusing, and 1343 * there are multiple description text for 1344 * deprecated address handling - worse, they 1345 * are not exactly the same. I believe 5.5.4 1346 * is the best one, so we follow 5.5.4. 1347 */ 1348 if (af == AF_INET6 && !ip6_use_deprecated) { 1349 struct in6_ifaddr *ia6; 1350 if ((ia6 = in6ifa_ifpwithaddr(m->m_pkthdr.rcvif, 1351 &ip6->ip6_dst)) && 1352 (ia6->ia6_flags & IN6_IFF_DEPRECATED)) { 1353 tp = NULL; 1354 goto dropwithreset; 1355 } 1356 } 1357 #endif 1358 1359 #ifdef IPSEC 1360 switch (af) { 1361 case AF_INET: 1362 if (ipsec4_in_reject_so(m, so)) { 1363 ipsecstat.in_polvio++; 1364 tp = NULL; 1365 goto dropwithreset; 1366 } 1367 break; 1368 #ifdef INET6 1369 case AF_INET6: 1370 if (ipsec6_in_reject_so(m, so)) { 1371 ipsec6stat.in_polvio++; 1372 tp = NULL; 1373 goto dropwithreset; 1374 } 1375 break; 1376 #endif 1377 } 1378 #endif 1379 1380 /* 1381 * LISTEN socket received a SYN 1382 * from itself? This can't possibly 1383 * be valid; drop the packet. 1384 */ 1385 if (th->th_sport == th->th_dport) { 1386 int i; 1387 1388 switch (af) { 1389 #ifdef INET 1390 case AF_INET: 1391 i = in_hosteq(ip->ip_src, ip->ip_dst); 1392 break; 1393 #endif 1394 #ifdef INET6 1395 case AF_INET6: 1396 i = IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &ip6->ip6_dst); 1397 break; 1398 #endif 1399 default: 1400 i = 1; 1401 } 1402 if (i) { 1403 tcpstat.tcps_badsyn++; 1404 goto drop; 1405 } 1406 } 1407 1408 /* 1409 * SYN looks ok; create compressed TCP 1410 * state for it. 1411 */ 1412 if (so->so_qlen <= so->so_qlimit && 1413 syn_cache_add(&src.sa, &dst.sa, th, tlen, 1414 so, m, optp, optlen, &opti)) 1415 m = NULL; 1416 } 1417 goto drop; 1418 } 1419 } 1420 1421 after_listen: 1422 #ifdef DIAGNOSTIC 1423 /* 1424 * Should not happen now that all embryonic connections 1425 * are handled with compressed state. 1426 */ 1427 if (tp->t_state == TCPS_LISTEN) 1428 panic("tcp_input: TCPS_LISTEN"); 1429 #endif 1430 1431 /* 1432 * Segment received on connection. 1433 * Reset idle time and keep-alive timer. 1434 */ 1435 tp->t_rcvtime = tcp_now; 1436 if (TCPS_HAVEESTABLISHED(tp->t_state)) 1437 TCP_TIMER_ARM(tp, TCPT_KEEP, tcp_keepidle); 1438 1439 /* 1440 * Process options. 1441 */ 1442 if (optp) 1443 tcp_dooptions(tp, optp, optlen, th, &opti); 1444 1445 /* 1446 * Header prediction: check for the two common cases 1447 * of a uni-directional data xfer. If the packet has 1448 * no control flags, is in-sequence, the window didn't 1449 * change and we're not retransmitting, it's a 1450 * candidate. If the length is zero and the ack moved 1451 * forward, we're the sender side of the xfer. Just 1452 * free the data acked & wake any higher level process 1453 * that was blocked waiting for space. If the length 1454 * is non-zero and the ack didn't move, we're the 1455 * receiver side. If we're getting packets in-order 1456 * (the reassembly queue is empty), add the data to 1457 * the socket buffer and note that we need a delayed ack. 1458 */ 1459 if (tp->t_state == TCPS_ESTABLISHED && 1460 (tiflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK && 1461 (!opti.ts_present || TSTMP_GEQ(opti.ts_val, tp->ts_recent)) && 1462 th->th_seq == tp->rcv_nxt && 1463 tiwin && tiwin == tp->snd_wnd && 1464 tp->snd_nxt == tp->snd_max) { 1465 1466 /* 1467 * If last ACK falls within this segment's sequence numbers, 1468 * record the timestamp. 1469 */ 1470 if (opti.ts_present && 1471 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 1472 SEQ_LT(tp->last_ack_sent, th->th_seq + tlen)) { 1473 tp->ts_recent_age = TCP_TIMESTAMP(tp); 1474 tp->ts_recent = opti.ts_val; 1475 } 1476 1477 if (tlen == 0) { 1478 if (SEQ_GT(th->th_ack, tp->snd_una) && 1479 SEQ_LEQ(th->th_ack, tp->snd_max) && 1480 tp->snd_cwnd >= tp->snd_wnd && 1481 tp->t_dupacks < tcprexmtthresh) { 1482 /* 1483 * this is a pure ack for outstanding data. 1484 */ 1485 ++tcpstat.tcps_predack; 1486 if (opti.ts_present && opti.ts_ecr) 1487 tcp_xmit_timer(tp, 1488 TCP_TIMESTAMP(tp) - opti.ts_ecr + 1); 1489 else if (tp->t_rtttime && 1490 SEQ_GT(th->th_ack, tp->t_rtseq)) 1491 tcp_xmit_timer(tp, 1492 tcp_now - tp->t_rtttime); 1493 acked = th->th_ack - tp->snd_una; 1494 tcpstat.tcps_rcvackpack++; 1495 tcpstat.tcps_rcvackbyte += acked; 1496 ND6_HINT(tp); 1497 1498 if (acked > (tp->t_lastoff - tp->t_inoff)) 1499 tp->t_lastm = NULL; 1500 sbdrop(&so->so_snd, acked); 1501 tp->t_lastoff -= acked; 1502 1503 /* 1504 * We want snd_recover to track snd_una to 1505 * avoid sequence wraparound problems for 1506 * very large transfers. 1507 */ 1508 tp->snd_una = tp->snd_recover = th->th_ack; 1509 m_freem(m); 1510 1511 /* 1512 * If all outstanding data are acked, stop 1513 * retransmit timer, otherwise restart timer 1514 * using current (possibly backed-off) value. 1515 * If process is waiting for space, 1516 * wakeup/selwakeup/signal. If data 1517 * are ready to send, let tcp_output 1518 * decide between more output or persist. 1519 */ 1520 if (tp->snd_una == tp->snd_max) 1521 TCP_TIMER_DISARM(tp, TCPT_REXMT); 1522 else if (TCP_TIMER_ISARMED(tp, 1523 TCPT_PERSIST) == 0) 1524 TCP_TIMER_ARM(tp, TCPT_REXMT, 1525 tp->t_rxtcur); 1526 1527 sowwakeup(so); 1528 if (so->so_snd.sb_cc) 1529 (void) tcp_output(tp); 1530 if (tcp_saveti) 1531 m_freem(tcp_saveti); 1532 return; 1533 } 1534 } else if (th->th_ack == tp->snd_una && 1535 TAILQ_FIRST(&tp->segq) == NULL && 1536 tlen <= sbspace(&so->so_rcv)) { 1537 /* 1538 * this is a pure, in-sequence data packet 1539 * with nothing on the reassembly queue and 1540 * we have enough buffer space to take it. 1541 */ 1542 ++tcpstat.tcps_preddat; 1543 tp->rcv_nxt += tlen; 1544 tcpstat.tcps_rcvpack++; 1545 tcpstat.tcps_rcvbyte += tlen; 1546 ND6_HINT(tp); 1547 /* 1548 * Drop TCP, IP headers and TCP options then add data 1549 * to socket buffer. 1550 */ 1551 if (so->so_state & SS_CANTRCVMORE) 1552 m_freem(m); 1553 else { 1554 m_adj(m, toff + off); 1555 sbappendstream(&so->so_rcv, m); 1556 } 1557 sorwakeup(so); 1558 TCP_SETUP_ACK(tp, th); 1559 if (tp->t_flags & TF_ACKNOW) 1560 (void) tcp_output(tp); 1561 if (tcp_saveti) 1562 m_freem(tcp_saveti); 1563 return; 1564 } 1565 } 1566 1567 /* 1568 * Compute mbuf offset to TCP data segment. 1569 */ 1570 hdroptlen = toff + off; 1571 1572 /* 1573 * Calculate amount of space in receive window, 1574 * and then do TCP input processing. 1575 * Receive window is amount of space in rcv queue, 1576 * but not less than advertised window. 1577 */ 1578 { int win; 1579 1580 win = sbspace(&so->so_rcv); 1581 if (win < 0) 1582 win = 0; 1583 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 1584 } 1585 1586 switch (tp->t_state) { 1587 case TCPS_LISTEN: 1588 /* 1589 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN 1590 */ 1591 if (m->m_flags & (M_BCAST|M_MCAST)) 1592 goto drop; 1593 switch (af) { 1594 #ifdef INET6 1595 case AF_INET6: 1596 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) 1597 goto drop; 1598 break; 1599 #endif /* INET6 */ 1600 case AF_INET: 1601 if (IN_MULTICAST(ip->ip_dst.s_addr) || 1602 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 1603 goto drop; 1604 break; 1605 } 1606 break; 1607 1608 /* 1609 * If the state is SYN_SENT: 1610 * if seg contains an ACK, but not for our SYN, drop the input. 1611 * if seg contains a RST, then drop the connection. 1612 * if seg does not contain SYN, then drop it. 1613 * Otherwise this is an acceptable SYN segment 1614 * initialize tp->rcv_nxt and tp->irs 1615 * if seg contains ack then advance tp->snd_una 1616 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 1617 * arrange for segment to be acked (eventually) 1618 * continue processing rest of data/controls, beginning with URG 1619 */ 1620 case TCPS_SYN_SENT: 1621 if ((tiflags & TH_ACK) && 1622 (SEQ_LEQ(th->th_ack, tp->iss) || 1623 SEQ_GT(th->th_ack, tp->snd_max))) 1624 goto dropwithreset; 1625 if (tiflags & TH_RST) { 1626 if (tiflags & TH_ACK) 1627 tp = tcp_drop(tp, ECONNREFUSED); 1628 goto drop; 1629 } 1630 if ((tiflags & TH_SYN) == 0) 1631 goto drop; 1632 if (tiflags & TH_ACK) { 1633 tp->snd_una = tp->snd_recover = th->th_ack; 1634 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 1635 tp->snd_nxt = tp->snd_una; 1636 TCP_TIMER_DISARM(tp, TCPT_REXMT); 1637 } 1638 tp->irs = th->th_seq; 1639 tcp_rcvseqinit(tp); 1640 tp->t_flags |= TF_ACKNOW; 1641 tcp_mss_from_peer(tp, opti.maxseg); 1642 1643 /* 1644 * Initialize the initial congestion window. If we 1645 * had to retransmit the SYN, we must initialize cwnd 1646 * to 1 segment (i.e. the Loss Window). 1647 */ 1648 if (tp->t_flags & TF_SYN_REXMT) 1649 tp->snd_cwnd = tp->t_peermss; 1650 else { 1651 int ss = tcp_init_win; 1652 #ifdef INET 1653 if (inp != NULL && in_localaddr(inp->inp_faddr)) 1654 ss = tcp_init_win_local; 1655 #endif 1656 #ifdef INET6 1657 if (in6p != NULL && in6_localaddr(&in6p->in6p_faddr)) 1658 ss = tcp_init_win_local; 1659 #endif 1660 tp->snd_cwnd = TCP_INITIAL_WINDOW(ss, tp->t_peermss); 1661 } 1662 1663 tcp_rmx_rtt(tp); 1664 if (tiflags & TH_ACK) { 1665 tcpstat.tcps_connects++; 1666 soisconnected(so); 1667 tcp_established(tp); 1668 /* Do window scaling on this connection? */ 1669 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 1670 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 1671 tp->snd_scale = tp->requested_s_scale; 1672 tp->rcv_scale = tp->request_r_scale; 1673 } 1674 TCP_REASS_LOCK(tp); 1675 (void) tcp_reass(tp, NULL, (struct mbuf *)0, &tlen); 1676 TCP_REASS_UNLOCK(tp); 1677 /* 1678 * if we didn't have to retransmit the SYN, 1679 * use its rtt as our initial srtt & rtt var. 1680 */ 1681 if (tp->t_rtttime) 1682 tcp_xmit_timer(tp, tcp_now - tp->t_rtttime); 1683 } else 1684 tp->t_state = TCPS_SYN_RECEIVED; 1685 1686 /* 1687 * Advance th->th_seq to correspond to first data byte. 1688 * If data, trim to stay within window, 1689 * dropping FIN if necessary. 1690 */ 1691 th->th_seq++; 1692 if (tlen > tp->rcv_wnd) { 1693 todrop = tlen - tp->rcv_wnd; 1694 m_adj(m, -todrop); 1695 tlen = tp->rcv_wnd; 1696 tiflags &= ~TH_FIN; 1697 tcpstat.tcps_rcvpackafterwin++; 1698 tcpstat.tcps_rcvbyteafterwin += todrop; 1699 } 1700 tp->snd_wl1 = th->th_seq - 1; 1701 tp->rcv_up = th->th_seq; 1702 goto step6; 1703 1704 /* 1705 * If the state is SYN_RECEIVED: 1706 * If seg contains an ACK, but not for our SYN, drop the input 1707 * and generate an RST. See page 36, rfc793 1708 */ 1709 case TCPS_SYN_RECEIVED: 1710 if ((tiflags & TH_ACK) && 1711 (SEQ_LEQ(th->th_ack, tp->iss) || 1712 SEQ_GT(th->th_ack, tp->snd_max))) 1713 goto dropwithreset; 1714 break; 1715 } 1716 1717 /* 1718 * States other than LISTEN or SYN_SENT. 1719 * First check timestamp, if present. 1720 * Then check that at least some bytes of segment are within 1721 * receive window. If segment begins before rcv_nxt, 1722 * drop leading data (and SYN); if nothing left, just ack. 1723 * 1724 * RFC 1323 PAWS: If we have a timestamp reply on this segment 1725 * and it's less than ts_recent, drop it. 1726 */ 1727 if (opti.ts_present && (tiflags & TH_RST) == 0 && tp->ts_recent && 1728 TSTMP_LT(opti.ts_val, tp->ts_recent)) { 1729 1730 /* Check to see if ts_recent is over 24 days old. */ 1731 if ((int)(TCP_TIMESTAMP(tp) - tp->ts_recent_age) > 1732 TCP_PAWS_IDLE) { 1733 /* 1734 * Invalidate ts_recent. If this segment updates 1735 * ts_recent, the age will be reset later and ts_recent 1736 * will get a valid value. If it does not, setting 1737 * ts_recent to zero will at least satisfy the 1738 * requirement that zero be placed in the timestamp 1739 * echo reply when ts_recent isn't valid. The 1740 * age isn't reset until we get a valid ts_recent 1741 * because we don't want out-of-order segments to be 1742 * dropped when ts_recent is old. 1743 */ 1744 tp->ts_recent = 0; 1745 } else { 1746 tcpstat.tcps_rcvduppack++; 1747 tcpstat.tcps_rcvdupbyte += tlen; 1748 tcpstat.tcps_pawsdrop++; 1749 goto dropafterack; 1750 } 1751 } 1752 1753 todrop = tp->rcv_nxt - th->th_seq; 1754 if (todrop > 0) { 1755 if (tiflags & TH_SYN) { 1756 tiflags &= ~TH_SYN; 1757 th->th_seq++; 1758 if (th->th_urp > 1) 1759 th->th_urp--; 1760 else { 1761 tiflags &= ~TH_URG; 1762 th->th_urp = 0; 1763 } 1764 todrop--; 1765 } 1766 if (todrop > tlen || 1767 (todrop == tlen && (tiflags & TH_FIN) == 0)) { 1768 /* 1769 * Any valid FIN must be to the left of the window. 1770 * At this point the FIN must be a duplicate or 1771 * out of sequence; drop it. 1772 */ 1773 tiflags &= ~TH_FIN; 1774 /* 1775 * Send an ACK to resynchronize and drop any data. 1776 * But keep on processing for RST or ACK. 1777 */ 1778 tp->t_flags |= TF_ACKNOW; 1779 todrop = tlen; 1780 tcpstat.tcps_rcvdupbyte += todrop; 1781 tcpstat.tcps_rcvduppack++; 1782 } else { 1783 tcpstat.tcps_rcvpartduppack++; 1784 tcpstat.tcps_rcvpartdupbyte += todrop; 1785 } 1786 hdroptlen += todrop; /*drop from head afterwards*/ 1787 th->th_seq += todrop; 1788 tlen -= todrop; 1789 if (th->th_urp > todrop) 1790 th->th_urp -= todrop; 1791 else { 1792 tiflags &= ~TH_URG; 1793 th->th_urp = 0; 1794 } 1795 } 1796 1797 /* 1798 * If new data are received on a connection after the 1799 * user processes are gone, then RST the other end. 1800 */ 1801 if ((so->so_state & SS_NOFDREF) && 1802 tp->t_state > TCPS_CLOSE_WAIT && tlen) { 1803 tp = tcp_close(tp); 1804 tcpstat.tcps_rcvafterclose++; 1805 goto dropwithreset; 1806 } 1807 1808 /* 1809 * If segment ends after window, drop trailing data 1810 * (and PUSH and FIN); if nothing left, just ACK. 1811 */ 1812 todrop = (th->th_seq + tlen) - (tp->rcv_nxt+tp->rcv_wnd); 1813 if (todrop > 0) { 1814 tcpstat.tcps_rcvpackafterwin++; 1815 if (todrop >= tlen) { 1816 tcpstat.tcps_rcvbyteafterwin += tlen; 1817 /* 1818 * If a new connection request is received 1819 * while in TIME_WAIT, drop the old connection 1820 * and start over if the sequence numbers 1821 * are above the previous ones. 1822 * 1823 * NOTE: We will checksum the packet again, and 1824 * so we need to put the header fields back into 1825 * network order! 1826 * XXX This kind of sucks, but we don't expect 1827 * XXX this to happen very often, so maybe it 1828 * XXX doesn't matter so much. 1829 */ 1830 if (tiflags & TH_SYN && 1831 tp->t_state == TCPS_TIME_WAIT && 1832 SEQ_GT(th->th_seq, tp->rcv_nxt)) { 1833 iss = tcp_new_iss(tp, tp->snd_nxt); 1834 tp = tcp_close(tp); 1835 TCP_FIELDS_TO_NET(th); 1836 goto findpcb; 1837 } 1838 /* 1839 * If window is closed can only take segments at 1840 * window edge, and have to drop data and PUSH from 1841 * incoming segments. Continue processing, but 1842 * remember to ack. Otherwise, drop segment 1843 * and ack. 1844 */ 1845 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 1846 tp->t_flags |= TF_ACKNOW; 1847 tcpstat.tcps_rcvwinprobe++; 1848 } else 1849 goto dropafterack; 1850 } else 1851 tcpstat.tcps_rcvbyteafterwin += todrop; 1852 m_adj(m, -todrop); 1853 tlen -= todrop; 1854 tiflags &= ~(TH_PUSH|TH_FIN); 1855 } 1856 1857 /* 1858 * If last ACK falls within this segment's sequence numbers, 1859 * and the timestamp is newer, record it. 1860 */ 1861 if (opti.ts_present && TSTMP_GEQ(opti.ts_val, tp->ts_recent) && 1862 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 1863 SEQ_LT(tp->last_ack_sent, th->th_seq + tlen + 1864 ((tiflags & (TH_SYN|TH_FIN)) != 0))) { 1865 tp->ts_recent_age = TCP_TIMESTAMP(tp); 1866 tp->ts_recent = opti.ts_val; 1867 } 1868 1869 /* 1870 * If the RST bit is set examine the state: 1871 * SYN_RECEIVED STATE: 1872 * If passive open, return to LISTEN state. 1873 * If active open, inform user that connection was refused. 1874 * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES: 1875 * Inform user that connection was reset, and close tcb. 1876 * CLOSING, LAST_ACK, TIME_WAIT STATES 1877 * Close the tcb. 1878 */ 1879 if (tiflags&TH_RST) switch (tp->t_state) { 1880 1881 case TCPS_SYN_RECEIVED: 1882 so->so_error = ECONNREFUSED; 1883 goto close; 1884 1885 case TCPS_ESTABLISHED: 1886 case TCPS_FIN_WAIT_1: 1887 case TCPS_FIN_WAIT_2: 1888 case TCPS_CLOSE_WAIT: 1889 so->so_error = ECONNRESET; 1890 close: 1891 tp->t_state = TCPS_CLOSED; 1892 tcpstat.tcps_drops++; 1893 tp = tcp_close(tp); 1894 goto drop; 1895 1896 case TCPS_CLOSING: 1897 case TCPS_LAST_ACK: 1898 case TCPS_TIME_WAIT: 1899 tp = tcp_close(tp); 1900 goto drop; 1901 } 1902 1903 /* 1904 * If a SYN is in the window, then this is an 1905 * error and we send an RST and drop the connection. 1906 */ 1907 if (tiflags & TH_SYN) { 1908 tp = tcp_drop(tp, ECONNRESET); 1909 goto dropwithreset; 1910 } 1911 1912 /* 1913 * If the ACK bit is off we drop the segment and return. 1914 */ 1915 if ((tiflags & TH_ACK) == 0) { 1916 if (tp->t_flags & TF_ACKNOW) 1917 goto dropafterack; 1918 else 1919 goto drop; 1920 } 1921 1922 /* 1923 * Ack processing. 1924 */ 1925 switch (tp->t_state) { 1926 1927 /* 1928 * In SYN_RECEIVED state if the ack ACKs our SYN then enter 1929 * ESTABLISHED state and continue processing, otherwise 1930 * send an RST. 1931 */ 1932 case TCPS_SYN_RECEIVED: 1933 if (SEQ_GT(tp->snd_una, th->th_ack) || 1934 SEQ_GT(th->th_ack, tp->snd_max)) 1935 goto dropwithreset; 1936 tcpstat.tcps_connects++; 1937 soisconnected(so); 1938 tcp_established(tp); 1939 /* Do window scaling? */ 1940 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 1941 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 1942 tp->snd_scale = tp->requested_s_scale; 1943 tp->rcv_scale = tp->request_r_scale; 1944 } 1945 TCP_REASS_LOCK(tp); 1946 (void) tcp_reass(tp, NULL, (struct mbuf *)0, &tlen); 1947 TCP_REASS_UNLOCK(tp); 1948 tp->snd_wl1 = th->th_seq - 1; 1949 /* fall into ... */ 1950 1951 /* 1952 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 1953 * ACKs. If the ack is in the range 1954 * tp->snd_una < th->th_ack <= tp->snd_max 1955 * then advance tp->snd_una to th->th_ack and drop 1956 * data from the retransmission queue. If this ACK reflects 1957 * more up to date window information we update our window information. 1958 */ 1959 case TCPS_ESTABLISHED: 1960 case TCPS_FIN_WAIT_1: 1961 case TCPS_FIN_WAIT_2: 1962 case TCPS_CLOSE_WAIT: 1963 case TCPS_CLOSING: 1964 case TCPS_LAST_ACK: 1965 case TCPS_TIME_WAIT: 1966 1967 if (SEQ_LEQ(th->th_ack, tp->snd_una)) { 1968 if (tlen == 0 && tiwin == tp->snd_wnd) { 1969 tcpstat.tcps_rcvdupack++; 1970 /* 1971 * If we have outstanding data (other than 1972 * a window probe), this is a completely 1973 * duplicate ack (ie, window info didn't 1974 * change), the ack is the biggest we've 1975 * seen and we've seen exactly our rexmt 1976 * threshhold of them, assume a packet 1977 * has been dropped and retransmit it. 1978 * Kludge snd_nxt & the congestion 1979 * window so we send only this one 1980 * packet. 1981 * 1982 * We know we're losing at the current 1983 * window size so do congestion avoidance 1984 * (set ssthresh to half the current window 1985 * and pull our congestion window back to 1986 * the new ssthresh). 1987 * 1988 * Dup acks mean that packets have left the 1989 * network (they're now cached at the receiver) 1990 * so bump cwnd by the amount in the receiver 1991 * to keep a constant cwnd packets in the 1992 * network. 1993 */ 1994 if (TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 || 1995 th->th_ack != tp->snd_una) 1996 tp->t_dupacks = 0; 1997 else if (++tp->t_dupacks == tcprexmtthresh) { 1998 tcp_seq onxt = tp->snd_nxt; 1999 u_int win = 2000 min(tp->snd_wnd, tp->snd_cwnd) / 2001 2 / tp->t_segsz; 2002 if (tcp_do_newreno && SEQ_LT(th->th_ack, 2003 tp->snd_recover)) { 2004 /* 2005 * False fast retransmit after 2006 * timeout. Do not cut window. 2007 */ 2008 tp->snd_cwnd += tp->t_segsz; 2009 tp->t_dupacks = 0; 2010 (void) tcp_output(tp); 2011 goto drop; 2012 } 2013 2014 if (win < 2) 2015 win = 2; 2016 tp->snd_ssthresh = win * tp->t_segsz; 2017 tp->snd_recover = tp->snd_max; 2018 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2019 tp->t_rtttime = 0; 2020 tp->snd_nxt = th->th_ack; 2021 tp->snd_cwnd = tp->t_segsz; 2022 (void) tcp_output(tp); 2023 tp->snd_cwnd = tp->snd_ssthresh + 2024 tp->t_segsz * tp->t_dupacks; 2025 if (SEQ_GT(onxt, tp->snd_nxt)) 2026 tp->snd_nxt = onxt; 2027 goto drop; 2028 } else if (tp->t_dupacks > tcprexmtthresh) { 2029 tp->snd_cwnd += tp->t_segsz; 2030 (void) tcp_output(tp); 2031 goto drop; 2032 } 2033 } else 2034 tp->t_dupacks = 0; 2035 break; 2036 } 2037 /* 2038 * If the congestion window was inflated to account 2039 * for the other side's cached packets, retract it. 2040 */ 2041 if (tcp_do_newreno == 0) { 2042 if (tp->t_dupacks >= tcprexmtthresh && 2043 tp->snd_cwnd > tp->snd_ssthresh) 2044 tp->snd_cwnd = tp->snd_ssthresh; 2045 tp->t_dupacks = 0; 2046 } else if (tp->t_dupacks >= tcprexmtthresh && 2047 tcp_newreno(tp, th) == 0) { 2048 tp->snd_cwnd = tp->snd_ssthresh; 2049 /* 2050 * Window inflation should have left us with approx. 2051 * snd_ssthresh outstanding data. But in case we 2052 * would be inclined to send a burst, better to do 2053 * it via the slow start mechanism. 2054 */ 2055 if (SEQ_SUB(tp->snd_max, th->th_ack) < tp->snd_ssthresh) 2056 tp->snd_cwnd = SEQ_SUB(tp->snd_max, th->th_ack) 2057 + tp->t_segsz; 2058 tp->t_dupacks = 0; 2059 } 2060 if (SEQ_GT(th->th_ack, tp->snd_max)) { 2061 tcpstat.tcps_rcvacktoomuch++; 2062 goto dropafterack; 2063 } 2064 acked = th->th_ack - tp->snd_una; 2065 tcpstat.tcps_rcvackpack++; 2066 tcpstat.tcps_rcvackbyte += acked; 2067 2068 /* 2069 * If we have a timestamp reply, update smoothed 2070 * round trip time. If no timestamp is present but 2071 * transmit timer is running and timed sequence 2072 * number was acked, update smoothed round trip time. 2073 * Since we now have an rtt measurement, cancel the 2074 * timer backoff (cf., Phil Karn's retransmit alg.). 2075 * Recompute the initial retransmit timer. 2076 */ 2077 if (opti.ts_present && opti.ts_ecr) 2078 tcp_xmit_timer(tp, TCP_TIMESTAMP(tp) - opti.ts_ecr + 1); 2079 else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) 2080 tcp_xmit_timer(tp, tcp_now - tp->t_rtttime); 2081 2082 /* 2083 * If all outstanding data is acked, stop retransmit 2084 * timer and remember to restart (more output or persist). 2085 * If there is more data to be acked, restart retransmit 2086 * timer, using current (possibly backed-off) value. 2087 */ 2088 if (th->th_ack == tp->snd_max) { 2089 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2090 needoutput = 1; 2091 } else if (TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) 2092 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 2093 /* 2094 * When new data is acked, open the congestion window. 2095 * If the window gives us less than ssthresh packets 2096 * in flight, open exponentially (segsz per packet). 2097 * Otherwise open linearly: segsz per window 2098 * (segsz^2 / cwnd per packet), plus a constant 2099 * fraction of a packet (segsz/8) to help larger windows 2100 * open quickly enough. 2101 */ 2102 { 2103 u_int cw = tp->snd_cwnd; 2104 u_int incr = tp->t_segsz; 2105 2106 if (cw > tp->snd_ssthresh) 2107 incr = incr * incr / cw; 2108 if (tcp_do_newreno == 0 || SEQ_GEQ(th->th_ack, tp->snd_recover)) 2109 tp->snd_cwnd = min(cw + incr, 2110 TCP_MAXWIN << tp->snd_scale); 2111 } 2112 ND6_HINT(tp); 2113 if (acked > so->so_snd.sb_cc) { 2114 tp->snd_wnd -= so->so_snd.sb_cc; 2115 sbdrop(&so->so_snd, (int)so->so_snd.sb_cc); 2116 ourfinisacked = 1; 2117 } else { 2118 if (acked > (tp->t_lastoff - tp->t_inoff)) 2119 tp->t_lastm = NULL; 2120 sbdrop(&so->so_snd, acked); 2121 tp->t_lastoff -= acked; 2122 ourfinisacked = 0; 2123 } 2124 sowwakeup(so); 2125 /* 2126 * We want snd_recover to track snd_una to 2127 * avoid sequence wraparound problems for 2128 * very large transfers. 2129 */ 2130 tp->snd_una = tp->snd_recover = th->th_ack; 2131 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2132 tp->snd_nxt = tp->snd_una; 2133 2134 switch (tp->t_state) { 2135 2136 /* 2137 * In FIN_WAIT_1 STATE in addition to the processing 2138 * for the ESTABLISHED state if our FIN is now acknowledged 2139 * then enter FIN_WAIT_2. 2140 */ 2141 case TCPS_FIN_WAIT_1: 2142 if (ourfinisacked) { 2143 /* 2144 * If we can't receive any more 2145 * data, then closing user can proceed. 2146 * Starting the timer is contrary to the 2147 * specification, but if we don't get a FIN 2148 * we'll hang forever. 2149 */ 2150 if (so->so_state & SS_CANTRCVMORE) { 2151 soisdisconnected(so); 2152 if (tcp_maxidle > 0) 2153 TCP_TIMER_ARM(tp, TCPT_2MSL, 2154 tcp_maxidle); 2155 } 2156 tp->t_state = TCPS_FIN_WAIT_2; 2157 } 2158 break; 2159 2160 /* 2161 * In CLOSING STATE in addition to the processing for 2162 * the ESTABLISHED state if the ACK acknowledges our FIN 2163 * then enter the TIME-WAIT state, otherwise ignore 2164 * the segment. 2165 */ 2166 case TCPS_CLOSING: 2167 if (ourfinisacked) { 2168 tp->t_state = TCPS_TIME_WAIT; 2169 tcp_canceltimers(tp); 2170 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 2171 soisdisconnected(so); 2172 } 2173 break; 2174 2175 /* 2176 * In LAST_ACK, we may still be waiting for data to drain 2177 * and/or to be acked, as well as for the ack of our FIN. 2178 * If our FIN is now acknowledged, delete the TCB, 2179 * enter the closed state and return. 2180 */ 2181 case TCPS_LAST_ACK: 2182 if (ourfinisacked) { 2183 tp = tcp_close(tp); 2184 goto drop; 2185 } 2186 break; 2187 2188 /* 2189 * In TIME_WAIT state the only thing that should arrive 2190 * is a retransmission of the remote FIN. Acknowledge 2191 * it and restart the finack timer. 2192 */ 2193 case TCPS_TIME_WAIT: 2194 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 2195 goto dropafterack; 2196 } 2197 } 2198 2199 step6: 2200 /* 2201 * Update window information. 2202 * Don't look at window if no ACK: TAC's send garbage on first SYN. 2203 */ 2204 if ((tiflags & TH_ACK) && (SEQ_LT(tp->snd_wl1, th->th_seq) || 2205 (tp->snd_wl1 == th->th_seq && SEQ_LT(tp->snd_wl2, th->th_ack)) || 2206 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))) { 2207 /* keep track of pure window updates */ 2208 if (tlen == 0 && 2209 tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) 2210 tcpstat.tcps_rcvwinupd++; 2211 tp->snd_wnd = tiwin; 2212 tp->snd_wl1 = th->th_seq; 2213 tp->snd_wl2 = th->th_ack; 2214 if (tp->snd_wnd > tp->max_sndwnd) 2215 tp->max_sndwnd = tp->snd_wnd; 2216 needoutput = 1; 2217 } 2218 2219 /* 2220 * Process segments with URG. 2221 */ 2222 if ((tiflags & TH_URG) && th->th_urp && 2223 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2224 /* 2225 * This is a kludge, but if we receive and accept 2226 * random urgent pointers, we'll crash in 2227 * soreceive. It's hard to imagine someone 2228 * actually wanting to send this much urgent data. 2229 */ 2230 if (th->th_urp + so->so_rcv.sb_cc > sb_max) { 2231 th->th_urp = 0; /* XXX */ 2232 tiflags &= ~TH_URG; /* XXX */ 2233 goto dodata; /* XXX */ 2234 } 2235 /* 2236 * If this segment advances the known urgent pointer, 2237 * then mark the data stream. This should not happen 2238 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 2239 * a FIN has been received from the remote side. 2240 * In these states we ignore the URG. 2241 * 2242 * According to RFC961 (Assigned Protocols), 2243 * the urgent pointer points to the last octet 2244 * of urgent data. We continue, however, 2245 * to consider it to indicate the first octet 2246 * of data past the urgent section as the original 2247 * spec states (in one of two places). 2248 */ 2249 if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) { 2250 tp->rcv_up = th->th_seq + th->th_urp; 2251 so->so_oobmark = so->so_rcv.sb_cc + 2252 (tp->rcv_up - tp->rcv_nxt) - 1; 2253 if (so->so_oobmark == 0) 2254 so->so_state |= SS_RCVATMARK; 2255 sohasoutofband(so); 2256 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); 2257 } 2258 /* 2259 * Remove out of band data so doesn't get presented to user. 2260 * This can happen independent of advancing the URG pointer, 2261 * but if two URG's are pending at once, some out-of-band 2262 * data may creep in... ick. 2263 */ 2264 if (th->th_urp <= (u_int16_t) tlen 2265 #ifdef SO_OOBINLINE 2266 && (so->so_options & SO_OOBINLINE) == 0 2267 #endif 2268 ) 2269 tcp_pulloutofband(so, th, m, hdroptlen); 2270 } else 2271 /* 2272 * If no out of band data is expected, 2273 * pull receive urgent pointer along 2274 * with the receive window. 2275 */ 2276 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) 2277 tp->rcv_up = tp->rcv_nxt; 2278 dodata: /* XXX */ 2279 2280 /* 2281 * Process the segment text, merging it into the TCP sequencing queue, 2282 * and arranging for acknowledgement of receipt if necessary. 2283 * This process logically involves adjusting tp->rcv_wnd as data 2284 * is presented to the user (this happens in tcp_usrreq.c, 2285 * case PRU_RCVD). If a FIN has already been received on this 2286 * connection then we just ignore the text. 2287 */ 2288 if ((tlen || (tiflags & TH_FIN)) && 2289 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2290 /* 2291 * Insert segment ti into reassembly queue of tcp with 2292 * control block tp. Return TH_FIN if reassembly now includes 2293 * a segment with FIN. The macro form does the common case 2294 * inline (segment is the next to be received on an 2295 * established connection, and the queue is empty), 2296 * avoiding linkage into and removal from the queue and 2297 * repetition of various conversions. 2298 * Set DELACK for segments received in order, but ack 2299 * immediately when segments are out of order 2300 * (so fast retransmit can work). 2301 */ 2302 /* NOTE: this was TCP_REASS() macro, but used only once */ 2303 TCP_REASS_LOCK(tp); 2304 if (th->th_seq == tp->rcv_nxt && 2305 TAILQ_FIRST(&tp->segq) == NULL && 2306 tp->t_state == TCPS_ESTABLISHED) { 2307 TCP_SETUP_ACK(tp, th); 2308 tp->rcv_nxt += tlen; 2309 tiflags = th->th_flags & TH_FIN; 2310 tcpstat.tcps_rcvpack++; 2311 tcpstat.tcps_rcvbyte += tlen; 2312 ND6_HINT(tp); 2313 if (so->so_state & SS_CANTRCVMORE) 2314 m_freem(m); 2315 else { 2316 m_adj(m, hdroptlen); 2317 sbappendstream(&(so)->so_rcv, m); 2318 } 2319 sorwakeup(so); 2320 } else { 2321 m_adj(m, hdroptlen); 2322 tiflags = tcp_reass(tp, th, m, &tlen); 2323 tp->t_flags |= TF_ACKNOW; 2324 } 2325 TCP_REASS_UNLOCK(tp); 2326 2327 /* 2328 * Note the amount of data that peer has sent into 2329 * our window, in order to estimate the sender's 2330 * buffer size. 2331 */ 2332 len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); 2333 } else { 2334 m_freem(m); 2335 m = NULL; 2336 tiflags &= ~TH_FIN; 2337 } 2338 2339 /* 2340 * If FIN is received ACK the FIN and let the user know 2341 * that the connection is closing. Ignore a FIN received before 2342 * the connection is fully established. 2343 */ 2344 if ((tiflags & TH_FIN) && TCPS_HAVEESTABLISHED(tp->t_state)) { 2345 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2346 socantrcvmore(so); 2347 tp->t_flags |= TF_ACKNOW; 2348 tp->rcv_nxt++; 2349 } 2350 switch (tp->t_state) { 2351 2352 /* 2353 * In ESTABLISHED STATE enter the CLOSE_WAIT state. 2354 */ 2355 case TCPS_ESTABLISHED: 2356 tp->t_state = TCPS_CLOSE_WAIT; 2357 break; 2358 2359 /* 2360 * If still in FIN_WAIT_1 STATE FIN has not been acked so 2361 * enter the CLOSING state. 2362 */ 2363 case TCPS_FIN_WAIT_1: 2364 tp->t_state = TCPS_CLOSING; 2365 break; 2366 2367 /* 2368 * In FIN_WAIT_2 state enter the TIME_WAIT state, 2369 * starting the time-wait timer, turning off the other 2370 * standard timers. 2371 */ 2372 case TCPS_FIN_WAIT_2: 2373 tp->t_state = TCPS_TIME_WAIT; 2374 tcp_canceltimers(tp); 2375 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 2376 soisdisconnected(so); 2377 break; 2378 2379 /* 2380 * In TIME_WAIT state restart the 2 MSL time_wait timer. 2381 */ 2382 case TCPS_TIME_WAIT: 2383 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 2384 break; 2385 } 2386 } 2387 #ifdef TCP_DEBUG 2388 if (so->so_options & SO_DEBUG) 2389 tcp_trace(TA_INPUT, ostate, tp, tcp_saveti, 0); 2390 #endif 2391 2392 /* 2393 * Return any desired output. 2394 */ 2395 if (needoutput || (tp->t_flags & TF_ACKNOW)) 2396 (void) tcp_output(tp); 2397 if (tcp_saveti) 2398 m_freem(tcp_saveti); 2399 return; 2400 2401 badsyn: 2402 /* 2403 * Received a bad SYN. Increment counters and dropwithreset. 2404 */ 2405 tcpstat.tcps_badsyn++; 2406 tp = NULL; 2407 goto dropwithreset; 2408 2409 dropafterack: 2410 /* 2411 * Generate an ACK dropping incoming segment if it occupies 2412 * sequence space, where the ACK reflects our state. 2413 */ 2414 if (tiflags & TH_RST) 2415 goto drop; 2416 m_freem(m); 2417 tp->t_flags |= TF_ACKNOW; 2418 (void) tcp_output(tp); 2419 if (tcp_saveti) 2420 m_freem(tcp_saveti); 2421 return; 2422 2423 dropwithreset_ratelim: 2424 /* 2425 * We may want to rate-limit RSTs in certain situations, 2426 * particularly if we are sending an RST in response to 2427 * an attempt to connect to or otherwise communicate with 2428 * a port for which we have no socket. 2429 */ 2430 if (ppsratecheck(&tcp_rst_ppslim_last, &tcp_rst_ppslim_count, 2431 tcp_rst_ppslim) == 0) { 2432 /* XXX stat */ 2433 goto drop; 2434 } 2435 /* ...fall into dropwithreset... */ 2436 2437 dropwithreset: 2438 /* 2439 * Generate a RST, dropping incoming segment. 2440 * Make ACK acceptable to originator of segment. 2441 */ 2442 if (tiflags & TH_RST) 2443 goto drop; 2444 2445 switch (af) { 2446 #ifdef INET6 2447 case AF_INET6: 2448 /* For following calls to tcp_respond */ 2449 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) 2450 goto drop; 2451 break; 2452 #endif /* INET6 */ 2453 case AF_INET: 2454 if (IN_MULTICAST(ip->ip_dst.s_addr) || 2455 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 2456 goto drop; 2457 } 2458 2459 if (tiflags & TH_ACK) 2460 (void)tcp_respond(tp, m, m, th, (tcp_seq)0, th->th_ack, TH_RST); 2461 else { 2462 if (tiflags & TH_SYN) 2463 tlen++; 2464 (void)tcp_respond(tp, m, m, th, th->th_seq + tlen, (tcp_seq)0, 2465 TH_RST|TH_ACK); 2466 } 2467 if (tcp_saveti) 2468 m_freem(tcp_saveti); 2469 return; 2470 2471 badcsum: 2472 tcpstat.tcps_rcvbadsum++; 2473 drop: 2474 /* 2475 * Drop space held by incoming segment and return. 2476 */ 2477 if (tp) { 2478 if (tp->t_inpcb) 2479 so = tp->t_inpcb->inp_socket; 2480 #ifdef INET6 2481 else if (tp->t_in6pcb) 2482 so = tp->t_in6pcb->in6p_socket; 2483 #endif 2484 else 2485 so = NULL; 2486 #ifdef TCP_DEBUG 2487 if (so && (so->so_options & SO_DEBUG) != 0) 2488 tcp_trace(TA_DROP, ostate, tp, tcp_saveti, 0); 2489 #endif 2490 } 2491 if (tcp_saveti) 2492 m_freem(tcp_saveti); 2493 m_freem(m); 2494 return; 2495 } 2496 2497 void 2498 tcp_dooptions(tp, cp, cnt, th, oi) 2499 struct tcpcb *tp; 2500 u_char *cp; 2501 int cnt; 2502 struct tcphdr *th; 2503 struct tcp_opt_info *oi; 2504 { 2505 u_int16_t mss; 2506 int opt, optlen; 2507 2508 for (; cnt > 0; cnt -= optlen, cp += optlen) { 2509 opt = cp[0]; 2510 if (opt == TCPOPT_EOL) 2511 break; 2512 if (opt == TCPOPT_NOP) 2513 optlen = 1; 2514 else { 2515 if (cnt < 2) 2516 break; 2517 optlen = cp[1]; 2518 if (optlen < 2 || optlen > cnt) 2519 break; 2520 } 2521 switch (opt) { 2522 2523 default: 2524 continue; 2525 2526 case TCPOPT_MAXSEG: 2527 if (optlen != TCPOLEN_MAXSEG) 2528 continue; 2529 if (!(th->th_flags & TH_SYN)) 2530 continue; 2531 bcopy(cp + 2, &mss, sizeof(mss)); 2532 oi->maxseg = ntohs(mss); 2533 break; 2534 2535 case TCPOPT_WINDOW: 2536 if (optlen != TCPOLEN_WINDOW) 2537 continue; 2538 if (!(th->th_flags & TH_SYN)) 2539 continue; 2540 tp->t_flags |= TF_RCVD_SCALE; 2541 tp->requested_s_scale = cp[2]; 2542 if (tp->requested_s_scale > TCP_MAX_WINSHIFT) { 2543 #if 0 /*XXX*/ 2544 char *p; 2545 2546 if (ip) 2547 p = ntohl(ip->ip_src); 2548 #ifdef INET6 2549 else if (ip6) 2550 p = ip6_sprintf(&ip6->ip6_src); 2551 #endif 2552 else 2553 p = "(unknown)"; 2554 log(LOG_ERR, "TCP: invalid wscale %d from %s, " 2555 "assuming %d\n", 2556 tp->requested_s_scale, p, 2557 TCP_MAX_WINSHIFT); 2558 #else 2559 log(LOG_ERR, "TCP: invalid wscale %d, " 2560 "assuming %d\n", 2561 tp->requested_s_scale, 2562 TCP_MAX_WINSHIFT); 2563 #endif 2564 tp->requested_s_scale = TCP_MAX_WINSHIFT; 2565 } 2566 break; 2567 2568 case TCPOPT_TIMESTAMP: 2569 if (optlen != TCPOLEN_TIMESTAMP) 2570 continue; 2571 oi->ts_present = 1; 2572 bcopy(cp + 2, &oi->ts_val, sizeof(oi->ts_val)); 2573 NTOHL(oi->ts_val); 2574 bcopy(cp + 6, &oi->ts_ecr, sizeof(oi->ts_ecr)); 2575 NTOHL(oi->ts_ecr); 2576 2577 /* 2578 * A timestamp received in a SYN makes 2579 * it ok to send timestamp requests and replies. 2580 */ 2581 if (th->th_flags & TH_SYN) { 2582 tp->t_flags |= TF_RCVD_TSTMP; 2583 tp->ts_recent = oi->ts_val; 2584 tp->ts_recent_age = TCP_TIMESTAMP(tp); 2585 } 2586 break; 2587 case TCPOPT_SACK_PERMITTED: 2588 if (optlen != TCPOLEN_SACK_PERMITTED) 2589 continue; 2590 if (!(th->th_flags & TH_SYN)) 2591 continue; 2592 tp->t_flags &= ~TF_CANT_TXSACK; 2593 break; 2594 2595 case TCPOPT_SACK: 2596 if (tp->t_flags & TF_IGNR_RXSACK) 2597 continue; 2598 if (optlen % 8 != 2 || optlen < 10) 2599 continue; 2600 cp += 2; 2601 optlen -= 2; 2602 for (; optlen > 0; cp -= 8, optlen -= 8) { 2603 tcp_seq lwe, rwe; 2604 bcopy((char *)cp, (char *) &lwe, sizeof(lwe)); 2605 NTOHL(lwe); 2606 bcopy((char *)cp, (char *) &rwe, sizeof(rwe)); 2607 NTOHL(rwe); 2608 /* tcp_mark_sacked(tp, lwe, rwe); */ 2609 } 2610 break; 2611 } 2612 } 2613 } 2614 2615 /* 2616 * Pull out of band byte out of a segment so 2617 * it doesn't appear in the user's data queue. 2618 * It is still reflected in the segment length for 2619 * sequencing purposes. 2620 */ 2621 void 2622 tcp_pulloutofband(so, th, m, off) 2623 struct socket *so; 2624 struct tcphdr *th; 2625 struct mbuf *m; 2626 int off; 2627 { 2628 int cnt = off + th->th_urp - 1; 2629 2630 while (cnt >= 0) { 2631 if (m->m_len > cnt) { 2632 char *cp = mtod(m, caddr_t) + cnt; 2633 struct tcpcb *tp = sototcpcb(so); 2634 2635 tp->t_iobc = *cp; 2636 tp->t_oobflags |= TCPOOB_HAVEDATA; 2637 bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); 2638 m->m_len--; 2639 return; 2640 } 2641 cnt -= m->m_len; 2642 m = m->m_next; 2643 if (m == 0) 2644 break; 2645 } 2646 panic("tcp_pulloutofband"); 2647 } 2648 2649 /* 2650 * Collect new round-trip time estimate 2651 * and update averages and current timeout. 2652 */ 2653 void 2654 tcp_xmit_timer(tp, rtt) 2655 struct tcpcb *tp; 2656 uint32_t rtt; 2657 { 2658 int32_t delta; 2659 2660 tcpstat.tcps_rttupdated++; 2661 if (tp->t_srtt != 0) { 2662 /* 2663 * srtt is stored as fixed point with 3 bits after the 2664 * binary point (i.e., scaled by 8). The following magic 2665 * is equivalent to the smoothing algorithm in rfc793 with 2666 * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed 2667 * point). Adjust rtt to origin 0. 2668 */ 2669 delta = (rtt << 2) - (tp->t_srtt >> TCP_RTT_SHIFT); 2670 if ((tp->t_srtt += delta) <= 0) 2671 tp->t_srtt = 1 << 2; 2672 /* 2673 * We accumulate a smoothed rtt variance (actually, a 2674 * smoothed mean difference), then set the retransmit 2675 * timer to smoothed rtt + 4 times the smoothed variance. 2676 * rttvar is stored as fixed point with 2 bits after the 2677 * binary point (scaled by 4). The following is 2678 * equivalent to rfc793 smoothing with an alpha of .75 2679 * (rttvar = rttvar*3/4 + |delta| / 4). This replaces 2680 * rfc793's wired-in beta. 2681 */ 2682 if (delta < 0) 2683 delta = -delta; 2684 delta -= (tp->t_rttvar >> TCP_RTTVAR_SHIFT); 2685 if ((tp->t_rttvar += delta) <= 0) 2686 tp->t_rttvar = 1 << 2; 2687 } else { 2688 /* 2689 * No rtt measurement yet - use the unsmoothed rtt. 2690 * Set the variance to half the rtt (so our first 2691 * retransmit happens at 3*rtt). 2692 */ 2693 tp->t_srtt = rtt << (TCP_RTT_SHIFT + 2); 2694 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT + 2 - 1); 2695 } 2696 tp->t_rtttime = 0; 2697 tp->t_rxtshift = 0; 2698 2699 /* 2700 * the retransmit should happen at rtt + 4 * rttvar. 2701 * Because of the way we do the smoothing, srtt and rttvar 2702 * will each average +1/2 tick of bias. When we compute 2703 * the retransmit timer, we want 1/2 tick of rounding and 2704 * 1 extra tick because of +-1/2 tick uncertainty in the 2705 * firing of the timer. The bias will give us exactly the 2706 * 1.5 tick we need. But, because the bias is 2707 * statistical, we have to test that we don't drop below 2708 * the minimum feasible timer (which is 2 ticks). 2709 */ 2710 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), 2711 max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX); 2712 2713 /* 2714 * We received an ack for a packet that wasn't retransmitted; 2715 * it is probably safe to discard any error indications we've 2716 * received recently. This isn't quite right, but close enough 2717 * for now (a route might have failed after we sent a segment, 2718 * and the return path might not be symmetrical). 2719 */ 2720 tp->t_softerror = 0; 2721 } 2722 2723 /* 2724 * Checks for partial ack. If partial ack arrives, force the retransmission 2725 * of the next unacknowledged segment, do not clear tp->t_dupacks, and return 2726 * 1. By setting snd_nxt to th_ack, this forces retransmission timer to 2727 * be started again. If the ack advances at least to tp->snd_recover, return 0. 2728 */ 2729 int 2730 tcp_newreno(tp, th) 2731 struct tcpcb *tp; 2732 struct tcphdr *th; 2733 { 2734 tcp_seq onxt = tp->snd_nxt; 2735 u_long ocwnd = tp->snd_cwnd; 2736 2737 if (SEQ_LT(th->th_ack, tp->snd_recover)) { 2738 /* 2739 * snd_una has not yet been updated and the socket's send 2740 * buffer has not yet drained off the ACK'd data, so we 2741 * have to leave snd_una as it was to get the correct data 2742 * offset in tcp_output(). 2743 */ 2744 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2745 tp->t_rtttime = 0; 2746 tp->snd_nxt = th->th_ack; 2747 /* 2748 * Set snd_cwnd to one segment beyond ACK'd offset. snd_una 2749 * is not yet updated when we're called. 2750 */ 2751 tp->snd_cwnd = tp->t_segsz + (th->th_ack - tp->snd_una); 2752 (void) tcp_output(tp); 2753 tp->snd_cwnd = ocwnd; 2754 if (SEQ_GT(onxt, tp->snd_nxt)) 2755 tp->snd_nxt = onxt; 2756 /* 2757 * Partial window deflation. Relies on fact that tp->snd_una 2758 * not updated yet. 2759 */ 2760 tp->snd_cwnd -= (th->th_ack - tp->snd_una - tp->t_segsz); 2761 return 1; 2762 } 2763 return 0; 2764 } 2765 2766 2767 /* 2768 * TCP compressed state engine. Currently used to hold compressed 2769 * state for SYN_RECEIVED. 2770 */ 2771 2772 u_long syn_cache_count; 2773 u_int32_t syn_hash1, syn_hash2; 2774 2775 #define SYN_HASH(sa, sp, dp) \ 2776 ((((sa)->s_addr^syn_hash1)*(((((u_int32_t)(dp))<<16) + \ 2777 ((u_int32_t)(sp)))^syn_hash2))) 2778 #ifndef INET6 2779 #define SYN_HASHALL(hash, src, dst) \ 2780 do { \ 2781 hash = SYN_HASH(&((struct sockaddr_in *)(src))->sin_addr, \ 2782 ((struct sockaddr_in *)(src))->sin_port, \ 2783 ((struct sockaddr_in *)(dst))->sin_port); \ 2784 } while (/*CONSTCOND*/ 0) 2785 #else 2786 #define SYN_HASH6(sa, sp, dp) \ 2787 ((((sa)->s6_addr32[0] ^ (sa)->s6_addr32[3] ^ syn_hash1) * \ 2788 (((((u_int32_t)(dp))<<16) + ((u_int32_t)(sp)))^syn_hash2)) \ 2789 & 0x7fffffff) 2790 2791 #define SYN_HASHALL(hash, src, dst) \ 2792 do { \ 2793 switch ((src)->sa_family) { \ 2794 case AF_INET: \ 2795 hash = SYN_HASH(&((struct sockaddr_in *)(src))->sin_addr, \ 2796 ((struct sockaddr_in *)(src))->sin_port, \ 2797 ((struct sockaddr_in *)(dst))->sin_port); \ 2798 break; \ 2799 case AF_INET6: \ 2800 hash = SYN_HASH6(&((struct sockaddr_in6 *)(src))->sin6_addr, \ 2801 ((struct sockaddr_in6 *)(src))->sin6_port, \ 2802 ((struct sockaddr_in6 *)(dst))->sin6_port); \ 2803 break; \ 2804 default: \ 2805 hash = 0; \ 2806 } \ 2807 } while (/*CONSTCOND*/0) 2808 #endif /* INET6 */ 2809 2810 #define SYN_CACHE_RM(sc) \ 2811 do { \ 2812 TAILQ_REMOVE(&tcp_syn_cache[(sc)->sc_bucketidx].sch_bucket, \ 2813 (sc), sc_bucketq); \ 2814 (sc)->sc_tp = NULL; \ 2815 LIST_REMOVE((sc), sc_tpq); \ 2816 tcp_syn_cache[(sc)->sc_bucketidx].sch_length--; \ 2817 callout_stop(&(sc)->sc_timer); \ 2818 syn_cache_count--; \ 2819 } while (/*CONSTCOND*/0) 2820 2821 #define SYN_CACHE_PUT(sc) \ 2822 do { \ 2823 if ((sc)->sc_ipopts) \ 2824 (void) m_free((sc)->sc_ipopts); \ 2825 if ((sc)->sc_route4.ro_rt != NULL) \ 2826 RTFREE((sc)->sc_route4.ro_rt); \ 2827 if (callout_invoking(&(sc)->sc_timer)) \ 2828 (sc)->sc_flags |= SCF_DEAD; \ 2829 else \ 2830 pool_put(&syn_cache_pool, (sc)); \ 2831 } while (/*CONSTCOND*/0) 2832 2833 struct pool syn_cache_pool; 2834 2835 /* 2836 * We don't estimate RTT with SYNs, so each packet starts with the default 2837 * RTT and each timer step has a fixed timeout value. 2838 */ 2839 #define SYN_CACHE_TIMER_ARM(sc) \ 2840 do { \ 2841 TCPT_RANGESET((sc)->sc_rxtcur, \ 2842 TCPTV_SRTTDFLT * tcp_backoff[(sc)->sc_rxtshift], TCPTV_MIN, \ 2843 TCPTV_REXMTMAX); \ 2844 callout_reset(&(sc)->sc_timer, \ 2845 (sc)->sc_rxtcur * (hz / PR_SLOWHZ), syn_cache_timer, (sc)); \ 2846 } while (/*CONSTCOND*/0) 2847 2848 #define SYN_CACHE_TIMESTAMP(sc) (tcp_now - (sc)->sc_timebase) 2849 2850 void 2851 syn_cache_init() 2852 { 2853 int i; 2854 2855 /* Initialize the hash buckets. */ 2856 for (i = 0; i < tcp_syn_cache_size; i++) 2857 TAILQ_INIT(&tcp_syn_cache[i].sch_bucket); 2858 2859 /* Initialize the syn cache pool. */ 2860 pool_init(&syn_cache_pool, sizeof(struct syn_cache), 0, 0, 0, 2861 "synpl", NULL); 2862 } 2863 2864 void 2865 syn_cache_insert(sc, tp) 2866 struct syn_cache *sc; 2867 struct tcpcb *tp; 2868 { 2869 struct syn_cache_head *scp; 2870 struct syn_cache *sc2; 2871 int s; 2872 2873 /* 2874 * If there are no entries in the hash table, reinitialize 2875 * the hash secrets. 2876 */ 2877 if (syn_cache_count == 0) { 2878 syn_hash1 = arc4random(); 2879 syn_hash2 = arc4random(); 2880 } 2881 2882 SYN_HASHALL(sc->sc_hash, &sc->sc_src.sa, &sc->sc_dst.sa); 2883 sc->sc_bucketidx = sc->sc_hash % tcp_syn_cache_size; 2884 scp = &tcp_syn_cache[sc->sc_bucketidx]; 2885 2886 /* 2887 * Make sure that we don't overflow the per-bucket 2888 * limit or the total cache size limit. 2889 */ 2890 s = splsoftnet(); 2891 if (scp->sch_length >= tcp_syn_bucket_limit) { 2892 tcpstat.tcps_sc_bucketoverflow++; 2893 /* 2894 * The bucket is full. Toss the oldest element in the 2895 * bucket. This will be the first entry in the bucket. 2896 */ 2897 sc2 = TAILQ_FIRST(&scp->sch_bucket); 2898 #ifdef DIAGNOSTIC 2899 /* 2900 * This should never happen; we should always find an 2901 * entry in our bucket. 2902 */ 2903 if (sc2 == NULL) 2904 panic("syn_cache_insert: bucketoverflow: impossible"); 2905 #endif 2906 SYN_CACHE_RM(sc2); 2907 SYN_CACHE_PUT(sc2); 2908 } else if (syn_cache_count >= tcp_syn_cache_limit) { 2909 struct syn_cache_head *scp2, *sce; 2910 2911 tcpstat.tcps_sc_overflowed++; 2912 /* 2913 * The cache is full. Toss the oldest entry in the 2914 * first non-empty bucket we can find. 2915 * 2916 * XXX We would really like to toss the oldest 2917 * entry in the cache, but we hope that this 2918 * condition doesn't happen very often. 2919 */ 2920 scp2 = scp; 2921 if (TAILQ_EMPTY(&scp2->sch_bucket)) { 2922 sce = &tcp_syn_cache[tcp_syn_cache_size]; 2923 for (++scp2; scp2 != scp; scp2++) { 2924 if (scp2 >= sce) 2925 scp2 = &tcp_syn_cache[0]; 2926 if (! TAILQ_EMPTY(&scp2->sch_bucket)) 2927 break; 2928 } 2929 #ifdef DIAGNOSTIC 2930 /* 2931 * This should never happen; we should always find a 2932 * non-empty bucket. 2933 */ 2934 if (scp2 == scp) 2935 panic("syn_cache_insert: cacheoverflow: " 2936 "impossible"); 2937 #endif 2938 } 2939 sc2 = TAILQ_FIRST(&scp2->sch_bucket); 2940 SYN_CACHE_RM(sc2); 2941 SYN_CACHE_PUT(sc2); 2942 } 2943 2944 /* 2945 * Initialize the entry's timer. 2946 */ 2947 sc->sc_rxttot = 0; 2948 sc->sc_rxtshift = 0; 2949 SYN_CACHE_TIMER_ARM(sc); 2950 2951 /* Link it from tcpcb entry */ 2952 LIST_INSERT_HEAD(&tp->t_sc, sc, sc_tpq); 2953 2954 /* Put it into the bucket. */ 2955 TAILQ_INSERT_TAIL(&scp->sch_bucket, sc, sc_bucketq); 2956 scp->sch_length++; 2957 syn_cache_count++; 2958 2959 tcpstat.tcps_sc_added++; 2960 splx(s); 2961 } 2962 2963 /* 2964 * Walk the timer queues, looking for SYN,ACKs that need to be retransmitted. 2965 * If we have retransmitted an entry the maximum number of times, expire 2966 * that entry. 2967 */ 2968 void 2969 syn_cache_timer(void *arg) 2970 { 2971 struct syn_cache *sc = arg; 2972 int s; 2973 2974 s = splsoftnet(); 2975 callout_ack(&sc->sc_timer); 2976 2977 if (__predict_false(sc->sc_flags & SCF_DEAD)) { 2978 tcpstat.tcps_sc_delayed_free++; 2979 pool_put(&syn_cache_pool, sc); 2980 splx(s); 2981 return; 2982 } 2983 2984 if (__predict_false(sc->sc_rxtshift == TCP_MAXRXTSHIFT)) { 2985 /* Drop it -- too many retransmissions. */ 2986 goto dropit; 2987 } 2988 2989 /* 2990 * Compute the total amount of time this entry has 2991 * been on a queue. If this entry has been on longer 2992 * than the keep alive timer would allow, expire it. 2993 */ 2994 sc->sc_rxttot += sc->sc_rxtcur; 2995 if (sc->sc_rxttot >= TCPTV_KEEP_INIT) 2996 goto dropit; 2997 2998 tcpstat.tcps_sc_retransmitted++; 2999 (void) syn_cache_respond(sc, NULL); 3000 3001 /* Advance the timer back-off. */ 3002 sc->sc_rxtshift++; 3003 SYN_CACHE_TIMER_ARM(sc); 3004 3005 splx(s); 3006 return; 3007 3008 dropit: 3009 tcpstat.tcps_sc_timed_out++; 3010 SYN_CACHE_RM(sc); 3011 SYN_CACHE_PUT(sc); 3012 splx(s); 3013 } 3014 3015 /* 3016 * Remove syn cache created by the specified tcb entry, 3017 * because this does not make sense to keep them 3018 * (if there's no tcb entry, syn cache entry will never be used) 3019 */ 3020 void 3021 syn_cache_cleanup(tp) 3022 struct tcpcb *tp; 3023 { 3024 struct syn_cache *sc, *nsc; 3025 int s; 3026 3027 s = splsoftnet(); 3028 3029 for (sc = LIST_FIRST(&tp->t_sc); sc != NULL; sc = nsc) { 3030 nsc = LIST_NEXT(sc, sc_tpq); 3031 3032 #ifdef DIAGNOSTIC 3033 if (sc->sc_tp != tp) 3034 panic("invalid sc_tp in syn_cache_cleanup"); 3035 #endif 3036 SYN_CACHE_RM(sc); 3037 SYN_CACHE_PUT(sc); 3038 } 3039 /* just for safety */ 3040 LIST_INIT(&tp->t_sc); 3041 3042 splx(s); 3043 } 3044 3045 /* 3046 * Find an entry in the syn cache. 3047 */ 3048 struct syn_cache * 3049 syn_cache_lookup(src, dst, headp) 3050 struct sockaddr *src; 3051 struct sockaddr *dst; 3052 struct syn_cache_head **headp; 3053 { 3054 struct syn_cache *sc; 3055 struct syn_cache_head *scp; 3056 u_int32_t hash; 3057 int s; 3058 3059 SYN_HASHALL(hash, src, dst); 3060 3061 scp = &tcp_syn_cache[hash % tcp_syn_cache_size]; 3062 *headp = scp; 3063 s = splsoftnet(); 3064 for (sc = TAILQ_FIRST(&scp->sch_bucket); sc != NULL; 3065 sc = TAILQ_NEXT(sc, sc_bucketq)) { 3066 if (sc->sc_hash != hash) 3067 continue; 3068 if (!bcmp(&sc->sc_src, src, src->sa_len) && 3069 !bcmp(&sc->sc_dst, dst, dst->sa_len)) { 3070 splx(s); 3071 return (sc); 3072 } 3073 } 3074 splx(s); 3075 return (NULL); 3076 } 3077 3078 /* 3079 * This function gets called when we receive an ACK for a 3080 * socket in the LISTEN state. We look up the connection 3081 * in the syn cache, and if its there, we pull it out of 3082 * the cache and turn it into a full-blown connection in 3083 * the SYN-RECEIVED state. 3084 * 3085 * The return values may not be immediately obvious, and their effects 3086 * can be subtle, so here they are: 3087 * 3088 * NULL SYN was not found in cache; caller should drop the 3089 * packet and send an RST. 3090 * 3091 * -1 We were unable to create the new connection, and are 3092 * aborting it. An ACK,RST is being sent to the peer 3093 * (unless we got screwey sequence numbners; see below), 3094 * because the 3-way handshake has been completed. Caller 3095 * should not free the mbuf, since we may be using it. If 3096 * we are not, we will free it. 3097 * 3098 * Otherwise, the return value is a pointer to the new socket 3099 * associated with the connection. 3100 */ 3101 struct socket * 3102 syn_cache_get(src, dst, th, hlen, tlen, so, m) 3103 struct sockaddr *src; 3104 struct sockaddr *dst; 3105 struct tcphdr *th; 3106 unsigned int hlen, tlen; 3107 struct socket *so; 3108 struct mbuf *m; 3109 { 3110 struct syn_cache *sc; 3111 struct syn_cache_head *scp; 3112 struct inpcb *inp = NULL; 3113 #ifdef INET6 3114 struct in6pcb *in6p = NULL; 3115 #endif 3116 struct tcpcb *tp = 0; 3117 struct mbuf *am; 3118 int s; 3119 struct socket *oso; 3120 3121 s = splsoftnet(); 3122 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 3123 splx(s); 3124 return (NULL); 3125 } 3126 3127 /* 3128 * Verify the sequence and ack numbers. Try getting the correct 3129 * response again. 3130 */ 3131 if ((th->th_ack != sc->sc_iss + 1) || 3132 SEQ_LEQ(th->th_seq, sc->sc_irs) || 3133 SEQ_GT(th->th_seq, sc->sc_irs + 1 + sc->sc_win)) { 3134 (void) syn_cache_respond(sc, m); 3135 splx(s); 3136 return ((struct socket *)(-1)); 3137 } 3138 3139 /* Remove this cache entry */ 3140 SYN_CACHE_RM(sc); 3141 splx(s); 3142 3143 /* 3144 * Ok, create the full blown connection, and set things up 3145 * as they would have been set up if we had created the 3146 * connection when the SYN arrived. If we can't create 3147 * the connection, abort it. 3148 */ 3149 /* 3150 * inp still has the OLD in_pcb stuff, set the 3151 * v6-related flags on the new guy, too. This is 3152 * done particularly for the case where an AF_INET6 3153 * socket is bound only to a port, and a v4 connection 3154 * comes in on that port. 3155 * we also copy the flowinfo from the original pcb 3156 * to the new one. 3157 */ 3158 oso = so; 3159 so = sonewconn(so, SS_ISCONNECTED); 3160 if (so == NULL) 3161 goto resetandabort; 3162 3163 switch (so->so_proto->pr_domain->dom_family) { 3164 #ifdef INET 3165 case AF_INET: 3166 inp = sotoinpcb(so); 3167 break; 3168 #endif 3169 #ifdef INET6 3170 case AF_INET6: 3171 in6p = sotoin6pcb(so); 3172 break; 3173 #endif 3174 } 3175 switch (src->sa_family) { 3176 #ifdef INET 3177 case AF_INET: 3178 if (inp) { 3179 inp->inp_laddr = ((struct sockaddr_in *)dst)->sin_addr; 3180 inp->inp_lport = ((struct sockaddr_in *)dst)->sin_port; 3181 inp->inp_options = ip_srcroute(); 3182 in_pcbstate(inp, INP_BOUND); 3183 if (inp->inp_options == NULL) { 3184 inp->inp_options = sc->sc_ipopts; 3185 sc->sc_ipopts = NULL; 3186 } 3187 } 3188 #ifdef INET6 3189 else if (in6p) { 3190 /* IPv4 packet to AF_INET6 socket */ 3191 bzero(&in6p->in6p_laddr, sizeof(in6p->in6p_laddr)); 3192 in6p->in6p_laddr.s6_addr16[5] = htons(0xffff); 3193 bcopy(&((struct sockaddr_in *)dst)->sin_addr, 3194 &in6p->in6p_laddr.s6_addr32[3], 3195 sizeof(((struct sockaddr_in *)dst)->sin_addr)); 3196 in6p->in6p_lport = ((struct sockaddr_in *)dst)->sin_port; 3197 in6totcpcb(in6p)->t_family = AF_INET; 3198 if (sotoin6pcb(oso)->in6p_flags & IN6P_IPV6_V6ONLY) 3199 in6p->in6p_flags |= IN6P_IPV6_V6ONLY; 3200 else 3201 in6p->in6p_flags &= ~IN6P_IPV6_V6ONLY; 3202 in6_pcbstate(in6p, IN6P_BOUND); 3203 } 3204 #endif 3205 break; 3206 #endif 3207 #ifdef INET6 3208 case AF_INET6: 3209 if (in6p) { 3210 in6p->in6p_laddr = ((struct sockaddr_in6 *)dst)->sin6_addr; 3211 in6p->in6p_lport = ((struct sockaddr_in6 *)dst)->sin6_port; 3212 in6_pcbstate(in6p, IN6P_BOUND); 3213 } 3214 break; 3215 #endif 3216 } 3217 #ifdef INET6 3218 if (in6p && in6totcpcb(in6p)->t_family == AF_INET6 && sotoinpcb(oso)) { 3219 struct in6pcb *oin6p = sotoin6pcb(oso); 3220 /* inherit socket options from the listening socket */ 3221 in6p->in6p_flags |= (oin6p->in6p_flags & IN6P_CONTROLOPTS); 3222 if (in6p->in6p_flags & IN6P_CONTROLOPTS) { 3223 m_freem(in6p->in6p_options); 3224 in6p->in6p_options = 0; 3225 } 3226 ip6_savecontrol(in6p, &in6p->in6p_options, 3227 mtod(m, struct ip6_hdr *), m); 3228 } 3229 #endif 3230 3231 #if defined(IPSEC) || defined(FAST_IPSEC) 3232 /* 3233 * we make a copy of policy, instead of sharing the policy, 3234 * for better behavior in terms of SA lookup and dead SA removal. 3235 */ 3236 if (inp) { 3237 /* copy old policy into new socket's */ 3238 if (ipsec_copy_pcbpolicy(sotoinpcb(oso)->inp_sp, inp->inp_sp)) 3239 printf("tcp_input: could not copy policy\n"); 3240 } 3241 #ifdef INET6 3242 else if (in6p) { 3243 /* copy old policy into new socket's */ 3244 if (ipsec_copy_pcbpolicy(sotoin6pcb(oso)->in6p_sp, 3245 in6p->in6p_sp)) 3246 printf("tcp_input: could not copy policy\n"); 3247 } 3248 #endif 3249 #endif 3250 3251 /* 3252 * Give the new socket our cached route reference. 3253 */ 3254 if (inp) 3255 inp->inp_route = sc->sc_route4; /* struct assignment */ 3256 #ifdef INET6 3257 else 3258 in6p->in6p_route = sc->sc_route6; 3259 #endif 3260 sc->sc_route4.ro_rt = NULL; 3261 3262 am = m_get(M_DONTWAIT, MT_SONAME); /* XXX */ 3263 if (am == NULL) 3264 goto resetandabort; 3265 MCLAIM(am, &tcp_mowner); 3266 am->m_len = src->sa_len; 3267 bcopy(src, mtod(am, caddr_t), src->sa_len); 3268 if (inp) { 3269 if (in_pcbconnect(inp, am)) { 3270 (void) m_free(am); 3271 goto resetandabort; 3272 } 3273 } 3274 #ifdef INET6 3275 else if (in6p) { 3276 if (src->sa_family == AF_INET) { 3277 /* IPv4 packet to AF_INET6 socket */ 3278 struct sockaddr_in6 *sin6; 3279 sin6 = mtod(am, struct sockaddr_in6 *); 3280 am->m_len = sizeof(*sin6); 3281 bzero(sin6, sizeof(*sin6)); 3282 sin6->sin6_family = AF_INET6; 3283 sin6->sin6_len = sizeof(*sin6); 3284 sin6->sin6_port = ((struct sockaddr_in *)src)->sin_port; 3285 sin6->sin6_addr.s6_addr16[5] = htons(0xffff); 3286 bcopy(&((struct sockaddr_in *)src)->sin_addr, 3287 &sin6->sin6_addr.s6_addr32[3], 3288 sizeof(sin6->sin6_addr.s6_addr32[3])); 3289 } 3290 if (in6_pcbconnect(in6p, am)) { 3291 (void) m_free(am); 3292 goto resetandabort; 3293 } 3294 } 3295 #endif 3296 else { 3297 (void) m_free(am); 3298 goto resetandabort; 3299 } 3300 (void) m_free(am); 3301 3302 if (inp) 3303 tp = intotcpcb(inp); 3304 #ifdef INET6 3305 else if (in6p) 3306 tp = in6totcpcb(in6p); 3307 #endif 3308 else 3309 tp = NULL; 3310 tp->t_flags = sototcpcb(oso)->t_flags & TF_NODELAY; 3311 if (sc->sc_request_r_scale != 15) { 3312 tp->requested_s_scale = sc->sc_requested_s_scale; 3313 tp->request_r_scale = sc->sc_request_r_scale; 3314 tp->snd_scale = sc->sc_requested_s_scale; 3315 tp->rcv_scale = sc->sc_request_r_scale; 3316 tp->t_flags |= TF_REQ_SCALE|TF_RCVD_SCALE; 3317 } 3318 if (sc->sc_flags & SCF_TIMESTAMP) 3319 tp->t_flags |= TF_REQ_TSTMP|TF_RCVD_TSTMP; 3320 tp->ts_timebase = sc->sc_timebase; 3321 3322 tp->t_template = tcp_template(tp); 3323 if (tp->t_template == 0) { 3324 tp = tcp_drop(tp, ENOBUFS); /* destroys socket */ 3325 so = NULL; 3326 m_freem(m); 3327 goto abort; 3328 } 3329 3330 tp->iss = sc->sc_iss; 3331 tp->irs = sc->sc_irs; 3332 tcp_sendseqinit(tp); 3333 tcp_rcvseqinit(tp); 3334 tp->t_state = TCPS_SYN_RECEIVED; 3335 TCP_TIMER_ARM(tp, TCPT_KEEP, TCPTV_KEEP_INIT); 3336 tcpstat.tcps_accepts++; 3337 3338 /* Initialize tp->t_ourmss before we deal with the peer's! */ 3339 tp->t_ourmss = sc->sc_ourmaxseg; 3340 tcp_mss_from_peer(tp, sc->sc_peermaxseg); 3341 3342 /* 3343 * Initialize the initial congestion window. If we 3344 * had to retransmit the SYN,ACK, we must initialize cwnd 3345 * to 1 segment (i.e. the Loss Window). 3346 */ 3347 if (sc->sc_rxtshift) 3348 tp->snd_cwnd = tp->t_peermss; 3349 else { 3350 int ss = tcp_init_win; 3351 #ifdef INET 3352 if (inp != NULL && in_localaddr(inp->inp_faddr)) 3353 ss = tcp_init_win_local; 3354 #endif 3355 #ifdef INET6 3356 if (in6p != NULL && in6_localaddr(&in6p->in6p_faddr)) 3357 ss = tcp_init_win_local; 3358 #endif 3359 tp->snd_cwnd = TCP_INITIAL_WINDOW(ss, tp->t_peermss); 3360 } 3361 3362 tcp_rmx_rtt(tp); 3363 tp->snd_wl1 = sc->sc_irs; 3364 tp->rcv_up = sc->sc_irs + 1; 3365 3366 /* 3367 * This is what whould have happened in tcp_output() when 3368 * the SYN,ACK was sent. 3369 */ 3370 tp->snd_up = tp->snd_una; 3371 tp->snd_max = tp->snd_nxt = tp->iss+1; 3372 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 3373 if (sc->sc_win > 0 && SEQ_GT(tp->rcv_nxt + sc->sc_win, tp->rcv_adv)) 3374 tp->rcv_adv = tp->rcv_nxt + sc->sc_win; 3375 tp->last_ack_sent = tp->rcv_nxt; 3376 3377 tcpstat.tcps_sc_completed++; 3378 SYN_CACHE_PUT(sc); 3379 return (so); 3380 3381 resetandabort: 3382 (void) tcp_respond(NULL, m, m, th, 3383 th->th_seq + tlen, (tcp_seq)0, TH_RST|TH_ACK); 3384 abort: 3385 if (so != NULL) 3386 (void) soabort(so); 3387 SYN_CACHE_PUT(sc); 3388 tcpstat.tcps_sc_aborted++; 3389 return ((struct socket *)(-1)); 3390 } 3391 3392 /* 3393 * This function is called when we get a RST for a 3394 * non-existent connection, so that we can see if the 3395 * connection is in the syn cache. If it is, zap it. 3396 */ 3397 3398 void 3399 syn_cache_reset(src, dst, th) 3400 struct sockaddr *src; 3401 struct sockaddr *dst; 3402 struct tcphdr *th; 3403 { 3404 struct syn_cache *sc; 3405 struct syn_cache_head *scp; 3406 int s = splsoftnet(); 3407 3408 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 3409 splx(s); 3410 return; 3411 } 3412 if (SEQ_LT(th->th_seq, sc->sc_irs) || 3413 SEQ_GT(th->th_seq, sc->sc_irs+1)) { 3414 splx(s); 3415 return; 3416 } 3417 SYN_CACHE_RM(sc); 3418 splx(s); 3419 tcpstat.tcps_sc_reset++; 3420 SYN_CACHE_PUT(sc); 3421 } 3422 3423 void 3424 syn_cache_unreach(src, dst, th) 3425 struct sockaddr *src; 3426 struct sockaddr *dst; 3427 struct tcphdr *th; 3428 { 3429 struct syn_cache *sc; 3430 struct syn_cache_head *scp; 3431 int s; 3432 3433 s = splsoftnet(); 3434 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 3435 splx(s); 3436 return; 3437 } 3438 /* If the sequence number != sc_iss, then it's a bogus ICMP msg */ 3439 if (ntohl (th->th_seq) != sc->sc_iss) { 3440 splx(s); 3441 return; 3442 } 3443 3444 /* 3445 * If we've retransmitted 3 times and this is our second error, 3446 * we remove the entry. Otherwise, we allow it to continue on. 3447 * This prevents us from incorrectly nuking an entry during a 3448 * spurious network outage. 3449 * 3450 * See tcp_notify(). 3451 */ 3452 if ((sc->sc_flags & SCF_UNREACH) == 0 || sc->sc_rxtshift < 3) { 3453 sc->sc_flags |= SCF_UNREACH; 3454 splx(s); 3455 return; 3456 } 3457 3458 SYN_CACHE_RM(sc); 3459 splx(s); 3460 tcpstat.tcps_sc_unreach++; 3461 SYN_CACHE_PUT(sc); 3462 } 3463 3464 /* 3465 * Given a LISTEN socket and an inbound SYN request, add 3466 * this to the syn cache, and send back a segment: 3467 * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK> 3468 * to the source. 3469 * 3470 * IMPORTANT NOTE: We do _NOT_ ACK data that might accompany the SYN. 3471 * Doing so would require that we hold onto the data and deliver it 3472 * to the application. However, if we are the target of a SYN-flood 3473 * DoS attack, an attacker could send data which would eventually 3474 * consume all available buffer space if it were ACKed. By not ACKing 3475 * the data, we avoid this DoS scenario. 3476 */ 3477 3478 int 3479 syn_cache_add(src, dst, th, hlen, so, m, optp, optlen, oi) 3480 struct sockaddr *src; 3481 struct sockaddr *dst; 3482 struct tcphdr *th; 3483 unsigned int hlen; 3484 struct socket *so; 3485 struct mbuf *m; 3486 u_char *optp; 3487 int optlen; 3488 struct tcp_opt_info *oi; 3489 { 3490 struct tcpcb tb, *tp; 3491 long win; 3492 struct syn_cache *sc; 3493 struct syn_cache_head *scp; 3494 struct mbuf *ipopts; 3495 3496 tp = sototcpcb(so); 3497 3498 /* 3499 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN 3500 * 3501 * Note this check is performed in tcp_input() very early on. 3502 */ 3503 3504 /* 3505 * Initialize some local state. 3506 */ 3507 win = sbspace(&so->so_rcv); 3508 if (win > TCP_MAXWIN) 3509 win = TCP_MAXWIN; 3510 3511 switch (src->sa_family) { 3512 #ifdef INET 3513 case AF_INET: 3514 /* 3515 * Remember the IP options, if any. 3516 */ 3517 ipopts = ip_srcroute(); 3518 break; 3519 #endif 3520 default: 3521 ipopts = NULL; 3522 } 3523 3524 if (optp) { 3525 tb.t_flags = tcp_do_rfc1323 ? (TF_REQ_SCALE|TF_REQ_TSTMP) : 0; 3526 tcp_dooptions(&tb, optp, optlen, th, oi); 3527 } else 3528 tb.t_flags = 0; 3529 3530 /* 3531 * See if we already have an entry for this connection. 3532 * If we do, resend the SYN,ACK. We do not count this 3533 * as a retransmission (XXX though maybe we should). 3534 */ 3535 if ((sc = syn_cache_lookup(src, dst, &scp)) != NULL) { 3536 tcpstat.tcps_sc_dupesyn++; 3537 if (ipopts) { 3538 /* 3539 * If we were remembering a previous source route, 3540 * forget it and use the new one we've been given. 3541 */ 3542 if (sc->sc_ipopts) 3543 (void) m_free(sc->sc_ipopts); 3544 sc->sc_ipopts = ipopts; 3545 } 3546 sc->sc_timestamp = tb.ts_recent; 3547 if (syn_cache_respond(sc, m) == 0) { 3548 tcpstat.tcps_sndacks++; 3549 tcpstat.tcps_sndtotal++; 3550 } 3551 return (1); 3552 } 3553 3554 sc = pool_get(&syn_cache_pool, PR_NOWAIT); 3555 if (sc == NULL) { 3556 if (ipopts) 3557 (void) m_free(ipopts); 3558 return (0); 3559 } 3560 3561 /* 3562 * Fill in the cache, and put the necessary IP and TCP 3563 * options into the reply. 3564 */ 3565 bzero(sc, sizeof(struct syn_cache)); 3566 callout_init(&sc->sc_timer); 3567 bcopy(src, &sc->sc_src, src->sa_len); 3568 bcopy(dst, &sc->sc_dst, dst->sa_len); 3569 sc->sc_flags = 0; 3570 sc->sc_ipopts = ipopts; 3571 sc->sc_irs = th->th_seq; 3572 switch (src->sa_family) { 3573 #ifdef INET 3574 case AF_INET: 3575 { 3576 struct sockaddr_in *srcin = (void *) src; 3577 struct sockaddr_in *dstin = (void *) dst; 3578 3579 sc->sc_iss = tcp_new_iss1(&dstin->sin_addr, 3580 &srcin->sin_addr, dstin->sin_port, 3581 srcin->sin_port, sizeof(dstin->sin_addr), 0); 3582 break; 3583 } 3584 #endif /* INET */ 3585 #ifdef INET6 3586 case AF_INET6: 3587 { 3588 struct sockaddr_in6 *srcin6 = (void *) src; 3589 struct sockaddr_in6 *dstin6 = (void *) dst; 3590 3591 sc->sc_iss = tcp_new_iss1(&dstin6->sin6_addr, 3592 &srcin6->sin6_addr, dstin6->sin6_port, 3593 srcin6->sin6_port, sizeof(dstin6->sin6_addr), 0); 3594 break; 3595 } 3596 #endif /* INET6 */ 3597 } 3598 sc->sc_peermaxseg = oi->maxseg; 3599 sc->sc_ourmaxseg = tcp_mss_to_advertise(m->m_flags & M_PKTHDR ? 3600 m->m_pkthdr.rcvif : NULL, 3601 sc->sc_src.sa.sa_family); 3602 sc->sc_win = win; 3603 sc->sc_timebase = tcp_now; /* see tcp_newtcpcb() */ 3604 sc->sc_timestamp = tb.ts_recent; 3605 if ((tb.t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP)) == 3606 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) 3607 sc->sc_flags |= SCF_TIMESTAMP; 3608 if ((tb.t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 3609 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 3610 sc->sc_requested_s_scale = tb.requested_s_scale; 3611 sc->sc_request_r_scale = 0; 3612 while (sc->sc_request_r_scale < TCP_MAX_WINSHIFT && 3613 TCP_MAXWIN << sc->sc_request_r_scale < 3614 so->so_rcv.sb_hiwat) 3615 sc->sc_request_r_scale++; 3616 } else { 3617 sc->sc_requested_s_scale = 15; 3618 sc->sc_request_r_scale = 15; 3619 } 3620 sc->sc_tp = tp; 3621 if (syn_cache_respond(sc, m) == 0) { 3622 syn_cache_insert(sc, tp); 3623 tcpstat.tcps_sndacks++; 3624 tcpstat.tcps_sndtotal++; 3625 } else { 3626 SYN_CACHE_PUT(sc); 3627 tcpstat.tcps_sc_dropped++; 3628 } 3629 return (1); 3630 } 3631 3632 int 3633 syn_cache_respond(sc, m) 3634 struct syn_cache *sc; 3635 struct mbuf *m; 3636 { 3637 struct route *ro; 3638 u_int8_t *optp; 3639 int optlen, error; 3640 u_int16_t tlen; 3641 struct ip *ip = NULL; 3642 #ifdef INET6 3643 struct ip6_hdr *ip6 = NULL; 3644 #endif 3645 struct tcpcb *tp; 3646 struct tcphdr *th; 3647 u_int hlen; 3648 struct socket *so; 3649 3650 switch (sc->sc_src.sa.sa_family) { 3651 case AF_INET: 3652 hlen = sizeof(struct ip); 3653 ro = &sc->sc_route4; 3654 break; 3655 #ifdef INET6 3656 case AF_INET6: 3657 hlen = sizeof(struct ip6_hdr); 3658 ro = (struct route *)&sc->sc_route6; 3659 break; 3660 #endif 3661 default: 3662 if (m) 3663 m_freem(m); 3664 return (EAFNOSUPPORT); 3665 } 3666 3667 /* Compute the size of the TCP options. */ 3668 optlen = 4 + (sc->sc_request_r_scale != 15 ? 4 : 0) + 3669 ((sc->sc_flags & SCF_TIMESTAMP) ? TCPOLEN_TSTAMP_APPA : 0); 3670 3671 tlen = hlen + sizeof(struct tcphdr) + optlen; 3672 3673 /* 3674 * Create the IP+TCP header from scratch. 3675 */ 3676 if (m) 3677 m_freem(m); 3678 #ifdef DIAGNOSTIC 3679 if (max_linkhdr + tlen > MCLBYTES) 3680 return (ENOBUFS); 3681 #endif 3682 MGETHDR(m, M_DONTWAIT, MT_DATA); 3683 if (m && tlen > MHLEN) { 3684 MCLGET(m, M_DONTWAIT); 3685 if ((m->m_flags & M_EXT) == 0) { 3686 m_freem(m); 3687 m = NULL; 3688 } 3689 } 3690 if (m == NULL) 3691 return (ENOBUFS); 3692 MCLAIM(m, &tcp_tx_mowner); 3693 3694 /* Fixup the mbuf. */ 3695 m->m_data += max_linkhdr; 3696 m->m_len = m->m_pkthdr.len = tlen; 3697 if (sc->sc_tp) { 3698 tp = sc->sc_tp; 3699 if (tp->t_inpcb) 3700 so = tp->t_inpcb->inp_socket; 3701 #ifdef INET6 3702 else if (tp->t_in6pcb) 3703 so = tp->t_in6pcb->in6p_socket; 3704 #endif 3705 else 3706 so = NULL; 3707 } else 3708 so = NULL; 3709 m->m_pkthdr.rcvif = NULL; 3710 memset(mtod(m, u_char *), 0, tlen); 3711 3712 switch (sc->sc_src.sa.sa_family) { 3713 case AF_INET: 3714 ip = mtod(m, struct ip *); 3715 ip->ip_dst = sc->sc_src.sin.sin_addr; 3716 ip->ip_src = sc->sc_dst.sin.sin_addr; 3717 ip->ip_p = IPPROTO_TCP; 3718 th = (struct tcphdr *)(ip + 1); 3719 th->th_dport = sc->sc_src.sin.sin_port; 3720 th->th_sport = sc->sc_dst.sin.sin_port; 3721 break; 3722 #ifdef INET6 3723 case AF_INET6: 3724 ip6 = mtod(m, struct ip6_hdr *); 3725 ip6->ip6_dst = sc->sc_src.sin6.sin6_addr; 3726 ip6->ip6_src = sc->sc_dst.sin6.sin6_addr; 3727 ip6->ip6_nxt = IPPROTO_TCP; 3728 /* ip6_plen will be updated in ip6_output() */ 3729 th = (struct tcphdr *)(ip6 + 1); 3730 th->th_dport = sc->sc_src.sin6.sin6_port; 3731 th->th_sport = sc->sc_dst.sin6.sin6_port; 3732 break; 3733 #endif 3734 default: 3735 th = NULL; 3736 } 3737 3738 th->th_seq = htonl(sc->sc_iss); 3739 th->th_ack = htonl(sc->sc_irs + 1); 3740 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 3741 th->th_flags = TH_SYN|TH_ACK; 3742 th->th_win = htons(sc->sc_win); 3743 /* th_sum already 0 */ 3744 /* th_urp already 0 */ 3745 3746 /* Tack on the TCP options. */ 3747 optp = (u_int8_t *)(th + 1); 3748 *optp++ = TCPOPT_MAXSEG; 3749 *optp++ = 4; 3750 *optp++ = (sc->sc_ourmaxseg >> 8) & 0xff; 3751 *optp++ = sc->sc_ourmaxseg & 0xff; 3752 3753 if (sc->sc_request_r_scale != 15) { 3754 *((u_int32_t *)optp) = htonl(TCPOPT_NOP << 24 | 3755 TCPOPT_WINDOW << 16 | TCPOLEN_WINDOW << 8 | 3756 sc->sc_request_r_scale); 3757 optp += 4; 3758 } 3759 3760 if (sc->sc_flags & SCF_TIMESTAMP) { 3761 u_int32_t *lp = (u_int32_t *)(optp); 3762 /* Form timestamp option as shown in appendix A of RFC 1323. */ 3763 *lp++ = htonl(TCPOPT_TSTAMP_HDR); 3764 *lp++ = htonl(SYN_CACHE_TIMESTAMP(sc)); 3765 *lp = htonl(sc->sc_timestamp); 3766 optp += TCPOLEN_TSTAMP_APPA; 3767 } 3768 3769 /* Compute the packet's checksum. */ 3770 switch (sc->sc_src.sa.sa_family) { 3771 case AF_INET: 3772 ip->ip_len = htons(tlen - hlen); 3773 th->th_sum = 0; 3774 th->th_sum = in_cksum(m, tlen); 3775 break; 3776 #ifdef INET6 3777 case AF_INET6: 3778 ip6->ip6_plen = htons(tlen - hlen); 3779 th->th_sum = 0; 3780 th->th_sum = in6_cksum(m, IPPROTO_TCP, hlen, tlen - hlen); 3781 break; 3782 #endif 3783 } 3784 3785 /* 3786 * Fill in some straggling IP bits. Note the stack expects 3787 * ip_len to be in host order, for convenience. 3788 */ 3789 switch (sc->sc_src.sa.sa_family) { 3790 #ifdef INET 3791 case AF_INET: 3792 ip->ip_len = htons(tlen); 3793 ip->ip_ttl = ip_defttl; 3794 /* XXX tos? */ 3795 break; 3796 #endif 3797 #ifdef INET6 3798 case AF_INET6: 3799 ip6->ip6_vfc &= ~IPV6_VERSION_MASK; 3800 ip6->ip6_vfc |= IPV6_VERSION; 3801 ip6->ip6_plen = htons(tlen - hlen); 3802 /* ip6_hlim will be initialized afterwards */ 3803 /* XXX flowlabel? */ 3804 break; 3805 #endif 3806 } 3807 3808 /* XXX use IPsec policy on listening socket, on SYN ACK */ 3809 tp = sc->sc_tp; 3810 3811 switch (sc->sc_src.sa.sa_family) { 3812 #ifdef INET 3813 case AF_INET: 3814 error = ip_output(m, sc->sc_ipopts, ro, 3815 (ip_mtudisc ? IP_MTUDISC : 0), 3816 (struct ip_moptions *)NULL, so); 3817 break; 3818 #endif 3819 #ifdef INET6 3820 case AF_INET6: 3821 ip6->ip6_hlim = in6_selecthlim(NULL, 3822 ro->ro_rt ? ro->ro_rt->rt_ifp : NULL); 3823 3824 error = ip6_output(m, NULL /*XXX*/, (struct route_in6 *)ro, 0, 3825 (struct ip6_moptions *)0, so, NULL); 3826 break; 3827 #endif 3828 default: 3829 error = EAFNOSUPPORT; 3830 break; 3831 } 3832 return (error); 3833 } 3834