1 /* $NetBSD: tcp_input.c,v 1.156 2002/10/16 15:15:28 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. All advertising materials mentioning features or use of this software 122 * must display the following acknowledgement: 123 * This product includes software developed by the University of 124 * California, Berkeley and its contributors. 125 * 4. Neither the name of the University nor the names of its contributors 126 * may be used to endorse or promote products derived from this software 127 * without specific prior written permission. 128 * 129 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 130 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 131 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 132 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 133 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 134 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 135 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 136 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 137 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 138 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 139 * SUCH DAMAGE. 140 * 141 * @(#)tcp_input.c 8.12 (Berkeley) 5/24/95 142 */ 143 144 /* 145 * TODO list for SYN cache stuff: 146 * 147 * Find room for a "state" field, which is needed to keep a 148 * compressed state for TIME_WAIT TCBs. It's been noted already 149 * that this is fairly important for very high-volume web and 150 * mail servers, which use a large number of short-lived 151 * connections. 152 */ 153 154 #include <sys/cdefs.h> 155 __KERNEL_RCSID(0, "$NetBSD: tcp_input.c,v 1.156 2002/10/16 15:15:28 itojun Exp $"); 156 157 #include "opt_inet.h" 158 #include "opt_ipsec.h" 159 #include "opt_inet_csum.h" 160 #include "opt_tcp_debug.h" 161 162 #include <sys/param.h> 163 #include <sys/systm.h> 164 #include <sys/malloc.h> 165 #include <sys/mbuf.h> 166 #include <sys/protosw.h> 167 #include <sys/socket.h> 168 #include <sys/socketvar.h> 169 #include <sys/errno.h> 170 #include <sys/syslog.h> 171 #include <sys/pool.h> 172 #include <sys/domain.h> 173 #include <sys/kernel.h> 174 175 #include <net/if.h> 176 #include <net/route.h> 177 #include <net/if_types.h> 178 179 #include <netinet/in.h> 180 #include <netinet/in_systm.h> 181 #include <netinet/ip.h> 182 #include <netinet/in_pcb.h> 183 #include <netinet/ip_var.h> 184 185 #ifdef INET6 186 #ifndef INET 187 #include <netinet/in.h> 188 #endif 189 #include <netinet/ip6.h> 190 #include <netinet6/ip6_var.h> 191 #include <netinet6/in6_pcb.h> 192 #include <netinet6/ip6_var.h> 193 #include <netinet6/in6_var.h> 194 #include <netinet/icmp6.h> 195 #include <netinet6/nd6.h> 196 #endif 197 198 #ifdef PULLDOWN_TEST 199 #ifndef INET6 200 /* always need ip6.h for IP6_EXTHDR_GET */ 201 #include <netinet/ip6.h> 202 #endif 203 #endif 204 205 #include <netinet/tcp.h> 206 #include <netinet/tcp_fsm.h> 207 #include <netinet/tcp_seq.h> 208 #include <netinet/tcp_timer.h> 209 #include <netinet/tcp_var.h> 210 #include <netinet/tcpip.h> 211 #include <netinet/tcp_debug.h> 212 213 #include <machine/stdarg.h> 214 215 #ifdef IPSEC 216 #include <netinet6/ipsec.h> 217 #include <netkey/key.h> 218 #endif /*IPSEC*/ 219 #ifdef INET6 220 #include "faith.h" 221 #if defined(NFAITH) && NFAITH > 0 222 #include <net/if_faith.h> 223 #endif 224 #endif 225 226 int tcprexmtthresh = 3; 227 int tcp_log_refused; 228 229 static int tcp_rst_ppslim_count = 0; 230 static struct timeval tcp_rst_ppslim_last; 231 232 #define TCP_PAWS_IDLE (24 * 24 * 60 * 60 * PR_SLOWHZ) 233 234 /* for modulo comparisons of timestamps */ 235 #define TSTMP_LT(a,b) ((int)((a)-(b)) < 0) 236 #define TSTMP_GEQ(a,b) ((int)((a)-(b)) >= 0) 237 238 /* 239 * Neighbor Discovery, Neighbor Unreachability Detection Upper layer hint. 240 */ 241 #ifdef INET6 242 #define ND6_HINT(tp) \ 243 do { \ 244 if (tp && tp->t_in6pcb && tp->t_family == AF_INET6 \ 245 && tp->t_in6pcb->in6p_route.ro_rt) { \ 246 nd6_nud_hint(tp->t_in6pcb->in6p_route.ro_rt, NULL, 0); \ 247 } \ 248 } while (0) 249 #else 250 #define ND6_HINT(tp) 251 #endif 252 253 /* 254 * Macro to compute ACK transmission behavior. Delay the ACK unless 255 * we have already delayed an ACK (must send an ACK every two segments). 256 * We also ACK immediately if we received a PUSH and the ACK-on-PUSH 257 * option is enabled. 258 */ 259 #define TCP_SETUP_ACK(tp, th) \ 260 do { \ 261 if ((tp)->t_flags & TF_DELACK || \ 262 (tcp_ack_on_push && (th)->th_flags & TH_PUSH)) \ 263 tp->t_flags |= TF_ACKNOW; \ 264 else \ 265 TCP_SET_DELACK(tp); \ 266 } while (0) 267 268 /* 269 * Convert TCP protocol fields to host order for easier processing. 270 */ 271 #define TCP_FIELDS_TO_HOST(th) \ 272 do { \ 273 NTOHL((th)->th_seq); \ 274 NTOHL((th)->th_ack); \ 275 NTOHS((th)->th_win); \ 276 NTOHS((th)->th_urp); \ 277 } while (0) 278 279 /* 280 * ... and reverse the above. 281 */ 282 #define TCP_FIELDS_TO_NET(th) \ 283 do { \ 284 HTONL((th)->th_seq); \ 285 HTONL((th)->th_ack); \ 286 HTONS((th)->th_win); \ 287 HTONS((th)->th_urp); \ 288 } while (0) 289 290 #ifdef TCP_CSUM_COUNTERS 291 #include <sys/device.h> 292 293 extern struct evcnt tcp_hwcsum_ok; 294 extern struct evcnt tcp_hwcsum_bad; 295 extern struct evcnt tcp_hwcsum_data; 296 extern struct evcnt tcp_swcsum; 297 298 #define TCP_CSUM_COUNTER_INCR(ev) (ev)->ev_count++ 299 300 #else 301 302 #define TCP_CSUM_COUNTER_INCR(ev) /* nothing */ 303 304 #endif /* TCP_CSUM_COUNTERS */ 305 306 #ifdef TCP_REASS_COUNTERS 307 #include <sys/device.h> 308 309 extern struct evcnt tcp_reass_; 310 extern struct evcnt tcp_reass_empty; 311 extern struct evcnt tcp_reass_iteration[8]; 312 extern struct evcnt tcp_reass_prependfirst; 313 extern struct evcnt tcp_reass_prepend; 314 extern struct evcnt tcp_reass_insert; 315 extern struct evcnt tcp_reass_inserttail; 316 extern struct evcnt tcp_reass_append; 317 extern struct evcnt tcp_reass_appendtail; 318 extern struct evcnt tcp_reass_overlaptail; 319 extern struct evcnt tcp_reass_overlapfront; 320 extern struct evcnt tcp_reass_segdup; 321 extern struct evcnt tcp_reass_fragdup; 322 323 #define TCP_REASS_COUNTER_INCR(ev) (ev)->ev_count++ 324 325 #else 326 327 #define TCP_REASS_COUNTER_INCR(ev) /* nothing */ 328 329 #endif /* TCP_REASS_COUNTERS */ 330 331 #ifdef INET 332 static void tcp4_log_refused __P((const struct ip *, const struct tcphdr *)); 333 #endif 334 #ifdef INET6 335 static void tcp6_log_refused 336 __P((const struct ip6_hdr *, const struct tcphdr *)); 337 #endif 338 339 int 340 tcp_reass(tp, th, m, tlen) 341 struct tcpcb *tp; 342 struct tcphdr *th; 343 struct mbuf *m; 344 int *tlen; 345 { 346 struct ipqent *p, *q, *nq, *tiqe = NULL; 347 struct socket *so = NULL; 348 int pkt_flags; 349 tcp_seq pkt_seq; 350 unsigned pkt_len; 351 u_long rcvpartdupbyte = 0; 352 u_long rcvoobyte; 353 #ifdef TCP_REASS_COUNTERS 354 u_int count = 0; 355 #endif 356 357 if (tp->t_inpcb) 358 so = tp->t_inpcb->inp_socket; 359 #ifdef INET6 360 else if (tp->t_in6pcb) 361 so = tp->t_in6pcb->in6p_socket; 362 #endif 363 364 TCP_REASS_LOCK_CHECK(tp); 365 366 /* 367 * Call with th==0 after become established to 368 * force pre-ESTABLISHED data up to user socket. 369 */ 370 if (th == 0) 371 goto present; 372 373 rcvoobyte = *tlen; 374 /* 375 * Copy these to local variables because the tcpiphdr 376 * gets munged while we are collapsing mbufs. 377 */ 378 pkt_seq = th->th_seq; 379 pkt_len = *tlen; 380 pkt_flags = th->th_flags; 381 382 TCP_REASS_COUNTER_INCR(&tcp_reass_); 383 384 if ((p = TAILQ_LAST(&tp->segq, ipqehead)) != NULL) { 385 /* 386 * When we miss a packet, the vast majority of time we get 387 * packets that follow it in order. So optimize for that. 388 */ 389 if (pkt_seq == p->ipqe_seq + p->ipqe_len) { 390 p->ipqe_len += pkt_len; 391 p->ipqe_flags |= pkt_flags; 392 m_cat(p->ipqe_m, m); 393 tiqe = p; 394 TAILQ_REMOVE(&tp->timeq, p, ipqe_timeq); 395 TCP_REASS_COUNTER_INCR(&tcp_reass_appendtail); 396 goto skip_replacement; 397 } 398 /* 399 * While we're here, if the pkt is completely beyond 400 * anything we have, just insert it at the tail. 401 */ 402 if (SEQ_GT(pkt_seq, p->ipqe_seq + p->ipqe_len)) { 403 TCP_REASS_COUNTER_INCR(&tcp_reass_inserttail); 404 goto insert_it; 405 } 406 } 407 408 q = TAILQ_FIRST(&tp->segq); 409 410 if (q != NULL) { 411 /* 412 * If this segment immediately precedes the first out-of-order 413 * block, simply slap the segment in front of it and (mostly) 414 * skip the complicated logic. 415 */ 416 if (pkt_seq + pkt_len == q->ipqe_seq) { 417 q->ipqe_seq = pkt_seq; 418 q->ipqe_len += pkt_len; 419 q->ipqe_flags |= pkt_flags; 420 m_cat(m, q->ipqe_m); 421 q->ipqe_m = m; 422 tiqe = q; 423 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 424 TCP_REASS_COUNTER_INCR(&tcp_reass_prependfirst); 425 goto skip_replacement; 426 } 427 } else { 428 TCP_REASS_COUNTER_INCR(&tcp_reass_empty); 429 } 430 431 /* 432 * Find a segment which begins after this one does. 433 */ 434 for (p = NULL; q != NULL; q = nq) { 435 nq = TAILQ_NEXT(q, ipqe_q); 436 #ifdef TCP_REASS_COUNTERS 437 count++; 438 #endif 439 /* 440 * If the received segment is just right after this 441 * fragment, merge the two together and then check 442 * for further overlaps. 443 */ 444 if (q->ipqe_seq + q->ipqe_len == pkt_seq) { 445 #ifdef TCPREASS_DEBUG 446 printf("tcp_reass[%p]: concat %u:%u(%u) to %u:%u(%u)\n", 447 tp, pkt_seq, pkt_seq + pkt_len, pkt_len, 448 q->ipqe_seq, q->ipqe_seq + q->ipqe_len, q->ipqe_len); 449 #endif 450 pkt_len += q->ipqe_len; 451 pkt_flags |= q->ipqe_flags; 452 pkt_seq = q->ipqe_seq; 453 m_cat(q->ipqe_m, m); 454 m = q->ipqe_m; 455 TCP_REASS_COUNTER_INCR(&tcp_reass_append); 456 goto free_ipqe; 457 } 458 /* 459 * If the received segment is completely past this 460 * fragment, we need to go the next fragment. 461 */ 462 if (SEQ_LT(q->ipqe_seq + q->ipqe_len, pkt_seq)) { 463 p = q; 464 continue; 465 } 466 /* 467 * If the fragment is past the received segment, 468 * it (or any following) can't be concatenated. 469 */ 470 if (SEQ_GT(q->ipqe_seq, pkt_seq + pkt_len)) { 471 TCP_REASS_COUNTER_INCR(&tcp_reass_insert); 472 break; 473 } 474 475 /* 476 * We've received all the data in this segment before. 477 * mark it as a duplicate and return. 478 */ 479 if (SEQ_LEQ(q->ipqe_seq, pkt_seq) && 480 SEQ_GEQ(q->ipqe_seq + q->ipqe_len, pkt_seq + pkt_len)) { 481 tcpstat.tcps_rcvduppack++; 482 tcpstat.tcps_rcvdupbyte += pkt_len; 483 m_freem(m); 484 if (tiqe != NULL) 485 pool_put(&ipqent_pool, tiqe); 486 TCP_REASS_COUNTER_INCR(&tcp_reass_segdup); 487 return (0); 488 } 489 /* 490 * Received segment completely overlaps this fragment 491 * so we drop the fragment (this keeps the temporal 492 * ordering of segments correct). 493 */ 494 if (SEQ_GEQ(q->ipqe_seq, pkt_seq) && 495 SEQ_LEQ(q->ipqe_seq + q->ipqe_len, pkt_seq + pkt_len)) { 496 rcvpartdupbyte += q->ipqe_len; 497 m_freem(q->ipqe_m); 498 TCP_REASS_COUNTER_INCR(&tcp_reass_fragdup); 499 goto free_ipqe; 500 } 501 /* 502 * RX'ed segment extends past the end of the 503 * fragment. Drop the overlapping bytes. Then 504 * merge the fragment and segment then treat as 505 * a longer received packet. 506 */ 507 if (SEQ_LT(q->ipqe_seq, pkt_seq) 508 && SEQ_GT(q->ipqe_seq + q->ipqe_len, pkt_seq)) { 509 int overlap = q->ipqe_seq + q->ipqe_len - pkt_seq; 510 #ifdef TCPREASS_DEBUG 511 printf("tcp_reass[%p]: trim starting %d bytes of %u:%u(%u)\n", 512 tp, overlap, 513 pkt_seq, pkt_seq + pkt_len, pkt_len); 514 #endif 515 m_adj(m, overlap); 516 rcvpartdupbyte += overlap; 517 m_cat(q->ipqe_m, m); 518 m = q->ipqe_m; 519 pkt_seq = q->ipqe_seq; 520 pkt_len += q->ipqe_len - overlap; 521 rcvoobyte -= overlap; 522 TCP_REASS_COUNTER_INCR(&tcp_reass_overlaptail); 523 goto free_ipqe; 524 } 525 /* 526 * RX'ed segment extends past the front of the 527 * fragment. Drop the overlapping bytes on the 528 * received packet. The packet will then be 529 * contatentated with this fragment a bit later. 530 */ 531 if (SEQ_GT(q->ipqe_seq, pkt_seq) 532 && SEQ_LT(q->ipqe_seq, pkt_seq + pkt_len)) { 533 int overlap = pkt_seq + pkt_len - q->ipqe_seq; 534 #ifdef TCPREASS_DEBUG 535 printf("tcp_reass[%p]: trim trailing %d bytes of %u:%u(%u)\n", 536 tp, overlap, 537 pkt_seq, pkt_seq + pkt_len, pkt_len); 538 #endif 539 m_adj(m, -overlap); 540 pkt_len -= overlap; 541 rcvpartdupbyte += overlap; 542 TCP_REASS_COUNTER_INCR(&tcp_reass_overlapfront); 543 rcvoobyte -= overlap; 544 } 545 /* 546 * If the received segment immediates precedes this 547 * fragment then tack the fragment onto this segment 548 * and reinsert the data. 549 */ 550 if (q->ipqe_seq == pkt_seq + pkt_len) { 551 #ifdef TCPREASS_DEBUG 552 printf("tcp_reass[%p]: append %u:%u(%u) to %u:%u(%u)\n", 553 tp, q->ipqe_seq, q->ipqe_seq + q->ipqe_len, q->ipqe_len, 554 pkt_seq, pkt_seq + pkt_len, pkt_len); 555 #endif 556 pkt_len += q->ipqe_len; 557 pkt_flags |= q->ipqe_flags; 558 m_cat(m, q->ipqe_m); 559 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 560 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 561 if (tiqe == NULL) { 562 tiqe = q; 563 } else { 564 pool_put(&ipqent_pool, q); 565 } 566 TCP_REASS_COUNTER_INCR(&tcp_reass_prepend); 567 break; 568 } 569 /* 570 * If the fragment is before the segment, remember it. 571 * When this loop is terminated, p will contain the 572 * pointer to fragment that is right before the received 573 * segment. 574 */ 575 if (SEQ_LEQ(q->ipqe_seq, pkt_seq)) 576 p = q; 577 578 continue; 579 580 /* 581 * This is a common operation. It also will allow 582 * to save doing a malloc/free in most instances. 583 */ 584 free_ipqe: 585 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 586 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 587 if (tiqe == NULL) { 588 tiqe = q; 589 } else { 590 pool_put(&ipqent_pool, q); 591 } 592 } 593 594 #ifdef TCP_REASS_COUNTERS 595 if (count > 7) 596 TCP_REASS_COUNTER_INCR(&tcp_reass_iteration[0]); 597 else if (count > 0) 598 TCP_REASS_COUNTER_INCR(&tcp_reass_iteration[count]); 599 #endif 600 601 insert_it: 602 603 /* 604 * Allocate a new queue entry since the received segment did not 605 * collapse onto any other out-of-order block; thus we are allocating 606 * a new block. If it had collapsed, tiqe would not be NULL and 607 * we would be reusing it. 608 * XXX If we can't, just drop the packet. XXX 609 */ 610 if (tiqe == NULL) { 611 tiqe = pool_get(&ipqent_pool, PR_NOWAIT); 612 if (tiqe == NULL) { 613 tcpstat.tcps_rcvmemdrop++; 614 m_freem(m); 615 return (0); 616 } 617 } 618 619 /* 620 * Update the counters. 621 */ 622 tcpstat.tcps_rcvoopack++; 623 tcpstat.tcps_rcvoobyte += rcvoobyte; 624 if (rcvpartdupbyte) { 625 tcpstat.tcps_rcvpartduppack++; 626 tcpstat.tcps_rcvpartdupbyte += rcvpartdupbyte; 627 } 628 629 /* 630 * Insert the new fragment queue entry into both queues. 631 */ 632 tiqe->ipqe_m = m; 633 tiqe->ipqe_seq = pkt_seq; 634 tiqe->ipqe_len = pkt_len; 635 tiqe->ipqe_flags = pkt_flags; 636 if (p == NULL) { 637 TAILQ_INSERT_HEAD(&tp->segq, tiqe, ipqe_q); 638 #ifdef TCPREASS_DEBUG 639 if (tiqe->ipqe_seq != tp->rcv_nxt) 640 printf("tcp_reass[%p]: insert %u:%u(%u) at front\n", 641 tp, pkt_seq, pkt_seq + pkt_len, pkt_len); 642 #endif 643 } else { 644 TAILQ_INSERT_AFTER(&tp->segq, p, tiqe, ipqe_q); 645 #ifdef TCPREASS_DEBUG 646 printf("tcp_reass[%p]: insert %u:%u(%u) after %u:%u(%u)\n", 647 tp, pkt_seq, pkt_seq + pkt_len, pkt_len, 648 p->ipqe_seq, p->ipqe_seq + p->ipqe_len, p->ipqe_len); 649 #endif 650 } 651 652 skip_replacement: 653 654 TAILQ_INSERT_HEAD(&tp->timeq, tiqe, ipqe_timeq); 655 656 present: 657 /* 658 * Present data to user, advancing rcv_nxt through 659 * completed sequence space. 660 */ 661 if (TCPS_HAVEESTABLISHED(tp->t_state) == 0) 662 return (0); 663 q = TAILQ_FIRST(&tp->segq); 664 if (q == NULL || q->ipqe_seq != tp->rcv_nxt) 665 return (0); 666 if (tp->t_state == TCPS_SYN_RECEIVED && q->ipqe_len) 667 return (0); 668 669 tp->rcv_nxt += q->ipqe_len; 670 pkt_flags = q->ipqe_flags & TH_FIN; 671 ND6_HINT(tp); 672 673 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 674 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 675 if (so->so_state & SS_CANTRCVMORE) 676 m_freem(q->ipqe_m); 677 else 678 sbappendstream(&so->so_rcv, q->ipqe_m); 679 pool_put(&ipqent_pool, q); 680 sorwakeup(so); 681 return (pkt_flags); 682 } 683 684 #ifdef INET6 685 int 686 tcp6_input(mp, offp, proto) 687 struct mbuf **mp; 688 int *offp, proto; 689 { 690 struct mbuf *m = *mp; 691 692 /* 693 * draft-itojun-ipv6-tcp-to-anycast 694 * better place to put this in? 695 */ 696 if (m->m_flags & M_ANYCAST6) { 697 struct ip6_hdr *ip6; 698 if (m->m_len < sizeof(struct ip6_hdr)) { 699 if ((m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) { 700 tcpstat.tcps_rcvshort++; 701 return IPPROTO_DONE; 702 } 703 } 704 ip6 = mtod(m, struct ip6_hdr *); 705 icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR, 706 (caddr_t)&ip6->ip6_dst - (caddr_t)ip6); 707 return IPPROTO_DONE; 708 } 709 710 tcp_input(m, *offp, proto); 711 return IPPROTO_DONE; 712 } 713 #endif 714 715 #ifdef INET 716 static void 717 tcp4_log_refused(ip, th) 718 const struct ip *ip; 719 const struct tcphdr *th; 720 { 721 char src[4*sizeof "123"]; 722 char dst[4*sizeof "123"]; 723 724 if (ip) { 725 strcpy(src, inet_ntoa(ip->ip_src)); 726 strcpy(dst, inet_ntoa(ip->ip_dst)); 727 } 728 else { 729 strcpy(src, "(unknown)"); 730 strcpy(dst, "(unknown)"); 731 } 732 log(LOG_INFO, 733 "Connection attempt to TCP %s:%d from %s:%d\n", 734 dst, ntohs(th->th_dport), 735 src, ntohs(th->th_sport)); 736 } 737 #endif 738 739 #ifdef INET6 740 static void 741 tcp6_log_refused(ip6, th) 742 const struct ip6_hdr *ip6; 743 const struct tcphdr *th; 744 { 745 char src[INET6_ADDRSTRLEN]; 746 char dst[INET6_ADDRSTRLEN]; 747 748 if (ip6) { 749 strcpy(src, ip6_sprintf(&ip6->ip6_src)); 750 strcpy(dst, ip6_sprintf(&ip6->ip6_dst)); 751 } 752 else { 753 strcpy(src, "(unknown v6)"); 754 strcpy(dst, "(unknown v6)"); 755 } 756 log(LOG_INFO, 757 "Connection attempt to TCP [%s]:%d from [%s]:%d\n", 758 dst, ntohs(th->th_dport), 759 src, ntohs(th->th_sport)); 760 } 761 #endif 762 763 /* 764 * TCP input routine, follows pages 65-76 of the 765 * protocol specification dated September, 1981 very closely. 766 */ 767 void 768 #if __STDC__ 769 tcp_input(struct mbuf *m, ...) 770 #else 771 tcp_input(m, va_alist) 772 struct mbuf *m; 773 #endif 774 { 775 int proto; 776 struct tcphdr *th; 777 struct ip *ip; 778 struct inpcb *inp; 779 #ifdef INET6 780 struct ip6_hdr *ip6; 781 struct in6pcb *in6p; 782 #endif 783 u_int8_t *optp = NULL; 784 int optlen = 0; 785 int len, tlen, toff, hdroptlen = 0; 786 struct tcpcb *tp = 0; 787 int tiflags; 788 struct socket *so = NULL; 789 int todrop, acked, ourfinisacked, needoutput = 0; 790 short ostate = 0; 791 int iss = 0; 792 u_long tiwin; 793 struct tcp_opt_info opti; 794 int off, iphlen; 795 va_list ap; 796 int af; /* af on the wire */ 797 struct mbuf *tcp_saveti = NULL; 798 799 va_start(ap, m); 800 toff = va_arg(ap, int); 801 proto = va_arg(ap, int); 802 va_end(ap); 803 804 tcpstat.tcps_rcvtotal++; 805 806 bzero(&opti, sizeof(opti)); 807 opti.ts_present = 0; 808 opti.maxseg = 0; 809 810 /* 811 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN. 812 * 813 * TCP is, by definition, unicast, so we reject all 814 * multicast outright. 815 * 816 * Note, there are additional src/dst address checks in 817 * the AF-specific code below. 818 */ 819 if (m->m_flags & (M_BCAST|M_MCAST)) { 820 /* XXX stat */ 821 goto drop; 822 } 823 #ifdef INET6 824 if (m->m_flags & M_ANYCAST6) { 825 /* XXX stat */ 826 goto drop; 827 } 828 #endif 829 830 /* 831 * Get IP and TCP header together in first mbuf. 832 * Note: IP leaves IP header in first mbuf. 833 */ 834 ip = mtod(m, struct ip *); 835 #ifdef INET6 836 ip6 = NULL; 837 #endif 838 switch (ip->ip_v) { 839 #ifdef INET 840 case 4: 841 af = AF_INET; 842 iphlen = sizeof(struct ip); 843 #ifndef PULLDOWN_TEST 844 /* would like to get rid of this... */ 845 if (toff > sizeof (struct ip)) { 846 ip_stripoptions(m, (struct mbuf *)0); 847 toff = sizeof(struct ip); 848 } 849 if (m->m_len < toff + sizeof (struct tcphdr)) { 850 if ((m = m_pullup(m, toff + sizeof (struct tcphdr))) == 0) { 851 tcpstat.tcps_rcvshort++; 852 return; 853 } 854 } 855 ip = mtod(m, struct ip *); 856 th = (struct tcphdr *)(mtod(m, caddr_t) + toff); 857 #else 858 ip = mtod(m, struct ip *); 859 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, 860 sizeof(struct tcphdr)); 861 if (th == NULL) { 862 tcpstat.tcps_rcvshort++; 863 return; 864 } 865 #endif 866 /* We do the checksum after PCB lookup... */ 867 len = ntohs(ip->ip_len); 868 tlen = len - toff; 869 break; 870 #endif 871 #ifdef INET6 872 case 6: 873 ip = NULL; 874 iphlen = sizeof(struct ip6_hdr); 875 af = AF_INET6; 876 #ifndef PULLDOWN_TEST 877 if (m->m_len < toff + sizeof(struct tcphdr)) { 878 m = m_pullup(m, toff + sizeof(struct tcphdr)); /*XXX*/ 879 if (m == NULL) { 880 tcpstat.tcps_rcvshort++; 881 return; 882 } 883 } 884 ip6 = mtod(m, struct ip6_hdr *); 885 th = (struct tcphdr *)(mtod(m, caddr_t) + toff); 886 #else 887 ip6 = mtod(m, struct ip6_hdr *); 888 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, 889 sizeof(struct tcphdr)); 890 if (th == NULL) { 891 tcpstat.tcps_rcvshort++; 892 return; 893 } 894 #endif 895 896 /* Be proactive about malicious use of IPv4 mapped address */ 897 if (IN6_IS_ADDR_V4MAPPED(&ip6->ip6_src) || 898 IN6_IS_ADDR_V4MAPPED(&ip6->ip6_dst)) { 899 /* XXX stat */ 900 goto drop; 901 } 902 903 /* 904 * Be proactive about unspecified IPv6 address in source. 905 * As we use all-zero to indicate unbounded/unconnected pcb, 906 * unspecified IPv6 address can be used to confuse us. 907 * 908 * Note that packets with unspecified IPv6 destination is 909 * already dropped in ip6_input. 910 */ 911 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 912 /* XXX stat */ 913 goto drop; 914 } 915 916 /* 917 * Make sure destination address is not multicast. 918 * Source address checked in ip6_input(). 919 */ 920 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) { 921 /* XXX stat */ 922 goto drop; 923 } 924 925 /* We do the checksum after PCB lookup... */ 926 len = m->m_pkthdr.len; 927 tlen = len - toff; 928 break; 929 #endif 930 default: 931 m_freem(m); 932 return; 933 } 934 935 KASSERT(TCP_HDR_ALIGNED_P(th)); 936 937 /* 938 * Check that TCP offset makes sense, 939 * pull out TCP options and adjust length. XXX 940 */ 941 off = th->th_off << 2; 942 if (off < sizeof (struct tcphdr) || off > tlen) { 943 tcpstat.tcps_rcvbadoff++; 944 goto drop; 945 } 946 tlen -= off; 947 948 /* 949 * tcp_input() has been modified to use tlen to mean the TCP data 950 * length throughout the function. Other functions can use 951 * m->m_pkthdr.len as the basis for calculating the TCP data length. 952 * rja 953 */ 954 955 if (off > sizeof (struct tcphdr)) { 956 #ifndef PULLDOWN_TEST 957 if (m->m_len < toff + off) { 958 if ((m = m_pullup(m, toff + off)) == 0) { 959 tcpstat.tcps_rcvshort++; 960 return; 961 } 962 switch (af) { 963 #ifdef INET 964 case AF_INET: 965 ip = mtod(m, struct ip *); 966 break; 967 #endif 968 #ifdef INET6 969 case AF_INET6: 970 ip6 = mtod(m, struct ip6_hdr *); 971 break; 972 #endif 973 } 974 th = (struct tcphdr *)(mtod(m, caddr_t) + toff); 975 } 976 #else 977 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, off); 978 if (th == NULL) { 979 tcpstat.tcps_rcvshort++; 980 return; 981 } 982 /* 983 * NOTE: ip/ip6 will not be affected by m_pulldown() 984 * (as they're before toff) and we don't need to update those. 985 */ 986 #endif 987 KASSERT(TCP_HDR_ALIGNED_P(th)); 988 optlen = off - sizeof (struct tcphdr); 989 optp = ((u_int8_t *)th) + sizeof(struct tcphdr); 990 /* 991 * Do quick retrieval of timestamp options ("options 992 * prediction?"). If timestamp is the only option and it's 993 * formatted as recommended in RFC 1323 appendix A, we 994 * quickly get the values now and not bother calling 995 * tcp_dooptions(), etc. 996 */ 997 if ((optlen == TCPOLEN_TSTAMP_APPA || 998 (optlen > TCPOLEN_TSTAMP_APPA && 999 optp[TCPOLEN_TSTAMP_APPA] == TCPOPT_EOL)) && 1000 *(u_int32_t *)optp == htonl(TCPOPT_TSTAMP_HDR) && 1001 (th->th_flags & TH_SYN) == 0) { 1002 opti.ts_present = 1; 1003 opti.ts_val = ntohl(*(u_int32_t *)(optp + 4)); 1004 opti.ts_ecr = ntohl(*(u_int32_t *)(optp + 8)); 1005 optp = NULL; /* we've parsed the options */ 1006 } 1007 } 1008 tiflags = th->th_flags; 1009 1010 /* 1011 * Locate pcb for segment. 1012 */ 1013 findpcb: 1014 inp = NULL; 1015 #ifdef INET6 1016 in6p = NULL; 1017 #endif 1018 switch (af) { 1019 #ifdef INET 1020 case AF_INET: 1021 inp = in_pcblookup_connect(&tcbtable, ip->ip_src, th->th_sport, 1022 ip->ip_dst, th->th_dport); 1023 if (inp == 0) { 1024 ++tcpstat.tcps_pcbhashmiss; 1025 inp = in_pcblookup_bind(&tcbtable, ip->ip_dst, th->th_dport); 1026 } 1027 #ifdef INET6 1028 if (inp == 0) { 1029 struct in6_addr s, d; 1030 1031 /* mapped addr case */ 1032 bzero(&s, sizeof(s)); 1033 s.s6_addr16[5] = htons(0xffff); 1034 bcopy(&ip->ip_src, &s.s6_addr32[3], sizeof(ip->ip_src)); 1035 bzero(&d, sizeof(d)); 1036 d.s6_addr16[5] = htons(0xffff); 1037 bcopy(&ip->ip_dst, &d.s6_addr32[3], sizeof(ip->ip_dst)); 1038 in6p = in6_pcblookup_connect(&tcb6, &s, th->th_sport, 1039 &d, th->th_dport, 0); 1040 if (in6p == 0) { 1041 ++tcpstat.tcps_pcbhashmiss; 1042 in6p = in6_pcblookup_bind(&tcb6, &d, 1043 th->th_dport, 0); 1044 } 1045 } 1046 #endif 1047 #ifndef INET6 1048 if (inp == 0) 1049 #else 1050 if (inp == 0 && in6p == 0) 1051 #endif 1052 { 1053 ++tcpstat.tcps_noport; 1054 if (tcp_log_refused && 1055 (tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) { 1056 tcp4_log_refused(ip, th); 1057 } 1058 TCP_FIELDS_TO_HOST(th); 1059 goto dropwithreset_ratelim; 1060 } 1061 #ifdef IPSEC 1062 if (inp && ipsec4_in_reject(m, inp)) { 1063 ipsecstat.in_polvio++; 1064 goto drop; 1065 } 1066 #ifdef INET6 1067 else if (in6p && ipsec4_in_reject_so(m, in6p->in6p_socket)) { 1068 ipsecstat.in_polvio++; 1069 goto drop; 1070 } 1071 #endif 1072 #endif /*IPSEC*/ 1073 break; 1074 #endif /*INET*/ 1075 #ifdef INET6 1076 case AF_INET6: 1077 { 1078 int faith; 1079 1080 #if defined(NFAITH) && NFAITH > 0 1081 faith = faithprefix(&ip6->ip6_dst); 1082 #else 1083 faith = 0; 1084 #endif 1085 in6p = in6_pcblookup_connect(&tcb6, &ip6->ip6_src, th->th_sport, 1086 &ip6->ip6_dst, th->th_dport, faith); 1087 if (in6p == NULL) { 1088 ++tcpstat.tcps_pcbhashmiss; 1089 in6p = in6_pcblookup_bind(&tcb6, &ip6->ip6_dst, 1090 th->th_dport, faith); 1091 } 1092 if (in6p == NULL) { 1093 ++tcpstat.tcps_noport; 1094 if (tcp_log_refused && 1095 (tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) { 1096 tcp6_log_refused(ip6, th); 1097 } 1098 TCP_FIELDS_TO_HOST(th); 1099 goto dropwithreset_ratelim; 1100 } 1101 #ifdef IPSEC 1102 if (ipsec6_in_reject(m, in6p)) { 1103 ipsec6stat.in_polvio++; 1104 goto drop; 1105 } 1106 #endif /*IPSEC*/ 1107 break; 1108 } 1109 #endif 1110 } 1111 1112 /* 1113 * If the state is CLOSED (i.e., TCB does not exist) then 1114 * all data in the incoming segment is discarded. 1115 * If the TCB exists but is in CLOSED state, it is embryonic, 1116 * but should either do a listen or a connect soon. 1117 */ 1118 tp = NULL; 1119 so = NULL; 1120 if (inp) { 1121 tp = intotcpcb(inp); 1122 so = inp->inp_socket; 1123 } 1124 #ifdef INET6 1125 else if (in6p) { 1126 tp = in6totcpcb(in6p); 1127 so = in6p->in6p_socket; 1128 } 1129 #endif 1130 if (tp == 0) { 1131 TCP_FIELDS_TO_HOST(th); 1132 goto dropwithreset_ratelim; 1133 } 1134 if (tp->t_state == TCPS_CLOSED) 1135 goto drop; 1136 1137 /* 1138 * Checksum extended TCP header and data. 1139 */ 1140 switch (af) { 1141 #ifdef INET 1142 case AF_INET: 1143 switch (m->m_pkthdr.csum_flags & 1144 ((m->m_pkthdr.rcvif->if_csum_flags_rx & M_CSUM_TCPv4) | 1145 M_CSUM_TCP_UDP_BAD | M_CSUM_DATA)) { 1146 case M_CSUM_TCPv4|M_CSUM_TCP_UDP_BAD: 1147 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_bad); 1148 goto badcsum; 1149 1150 case M_CSUM_TCPv4|M_CSUM_DATA: 1151 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_data); 1152 if ((m->m_pkthdr.csum_data ^ 0xffff) != 0) 1153 goto badcsum; 1154 break; 1155 1156 case M_CSUM_TCPv4: 1157 /* Checksum was okay. */ 1158 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_ok); 1159 break; 1160 1161 default: 1162 /* Must compute it ourselves. */ 1163 TCP_CSUM_COUNTER_INCR(&tcp_swcsum); 1164 #ifndef PULLDOWN_TEST 1165 { 1166 struct ipovly *ipov; 1167 ipov = (struct ipovly *)ip; 1168 bzero(ipov->ih_x1, sizeof ipov->ih_x1); 1169 ipov->ih_len = htons(tlen + off); 1170 1171 if (in_cksum(m, len) != 0) 1172 goto badcsum; 1173 } 1174 #else 1175 if (in4_cksum(m, IPPROTO_TCP, toff, tlen + off) != 0) 1176 goto badcsum; 1177 #endif /* ! PULLDOWN_TEST */ 1178 break; 1179 } 1180 break; 1181 #endif /* INET4 */ 1182 1183 #ifdef INET6 1184 case AF_INET6: 1185 if (in6_cksum(m, IPPROTO_TCP, toff, tlen + off) != 0) 1186 goto badcsum; 1187 break; 1188 #endif /* INET6 */ 1189 } 1190 1191 TCP_FIELDS_TO_HOST(th); 1192 1193 /* Unscale the window into a 32-bit value. */ 1194 if ((tiflags & TH_SYN) == 0) 1195 tiwin = th->th_win << tp->snd_scale; 1196 else 1197 tiwin = th->th_win; 1198 1199 #ifdef INET6 1200 /* save packet options if user wanted */ 1201 if (in6p && (in6p->in6p_flags & IN6P_CONTROLOPTS)) { 1202 if (in6p->in6p_options) { 1203 m_freem(in6p->in6p_options); 1204 in6p->in6p_options = 0; 1205 } 1206 ip6_savecontrol(in6p, &in6p->in6p_options, ip6, m); 1207 } 1208 #endif 1209 1210 if (so->so_options & (SO_DEBUG|SO_ACCEPTCONN)) { 1211 union syn_cache_sa src; 1212 union syn_cache_sa dst; 1213 1214 bzero(&src, sizeof(src)); 1215 bzero(&dst, sizeof(dst)); 1216 switch (af) { 1217 #ifdef INET 1218 case AF_INET: 1219 src.sin.sin_len = sizeof(struct sockaddr_in); 1220 src.sin.sin_family = AF_INET; 1221 src.sin.sin_addr = ip->ip_src; 1222 src.sin.sin_port = th->th_sport; 1223 1224 dst.sin.sin_len = sizeof(struct sockaddr_in); 1225 dst.sin.sin_family = AF_INET; 1226 dst.sin.sin_addr = ip->ip_dst; 1227 dst.sin.sin_port = th->th_dport; 1228 break; 1229 #endif 1230 #ifdef INET6 1231 case AF_INET6: 1232 src.sin6.sin6_len = sizeof(struct sockaddr_in6); 1233 src.sin6.sin6_family = AF_INET6; 1234 src.sin6.sin6_addr = ip6->ip6_src; 1235 src.sin6.sin6_port = th->th_sport; 1236 1237 dst.sin6.sin6_len = sizeof(struct sockaddr_in6); 1238 dst.sin6.sin6_family = AF_INET6; 1239 dst.sin6.sin6_addr = ip6->ip6_dst; 1240 dst.sin6.sin6_port = th->th_dport; 1241 break; 1242 #endif /* INET6 */ 1243 default: 1244 goto badsyn; /*sanity*/ 1245 } 1246 1247 if (so->so_options & SO_DEBUG) { 1248 ostate = tp->t_state; 1249 1250 tcp_saveti = NULL; 1251 if (iphlen + sizeof(struct tcphdr) > MHLEN) 1252 goto nosave; 1253 1254 if (m->m_len > iphlen && (m->m_flags & M_EXT) == 0) { 1255 tcp_saveti = m_copym(m, 0, iphlen, M_DONTWAIT); 1256 if (!tcp_saveti) 1257 goto nosave; 1258 } else { 1259 MGETHDR(tcp_saveti, M_DONTWAIT, MT_HEADER); 1260 if (!tcp_saveti) 1261 goto nosave; 1262 tcp_saveti->m_len = iphlen; 1263 m_copydata(m, 0, iphlen, 1264 mtod(tcp_saveti, caddr_t)); 1265 } 1266 1267 if (M_TRAILINGSPACE(tcp_saveti) < sizeof(struct tcphdr)) { 1268 m_freem(tcp_saveti); 1269 tcp_saveti = NULL; 1270 } else { 1271 tcp_saveti->m_len += sizeof(struct tcphdr); 1272 bcopy(th, mtod(tcp_saveti, caddr_t) + iphlen, 1273 sizeof(struct tcphdr)); 1274 } 1275 if (tcp_saveti) { 1276 /* 1277 * need to recover version # field, which was 1278 * overwritten on ip_cksum computation. 1279 */ 1280 struct ip *sip; 1281 sip = mtod(tcp_saveti, struct ip *); 1282 switch (af) { 1283 #ifdef INET 1284 case AF_INET: 1285 sip->ip_v = 4; 1286 break; 1287 #endif 1288 #ifdef INET6 1289 case AF_INET6: 1290 sip->ip_v = 6; 1291 break; 1292 #endif 1293 } 1294 } 1295 nosave:; 1296 } 1297 if (so->so_options & SO_ACCEPTCONN) { 1298 if ((tiflags & (TH_RST|TH_ACK|TH_SYN)) != TH_SYN) { 1299 if (tiflags & TH_RST) { 1300 syn_cache_reset(&src.sa, &dst.sa, th); 1301 } else if ((tiflags & (TH_ACK|TH_SYN)) == 1302 (TH_ACK|TH_SYN)) { 1303 /* 1304 * Received a SYN,ACK. This should 1305 * never happen while we are in 1306 * LISTEN. Send an RST. 1307 */ 1308 goto badsyn; 1309 } else if (tiflags & TH_ACK) { 1310 so = syn_cache_get(&src.sa, &dst.sa, 1311 th, toff, tlen, so, m); 1312 if (so == NULL) { 1313 /* 1314 * We don't have a SYN for 1315 * this ACK; send an RST. 1316 */ 1317 goto badsyn; 1318 } else if (so == 1319 (struct socket *)(-1)) { 1320 /* 1321 * We were unable to create 1322 * the connection. If the 1323 * 3-way handshake was 1324 * completed, and RST has 1325 * been sent to the peer. 1326 * Since the mbuf might be 1327 * in use for the reply, 1328 * do not free it. 1329 */ 1330 m = NULL; 1331 } else { 1332 /* 1333 * We have created a 1334 * full-blown connection. 1335 */ 1336 tp = NULL; 1337 inp = NULL; 1338 #ifdef INET6 1339 in6p = NULL; 1340 #endif 1341 switch (so->so_proto->pr_domain->dom_family) { 1342 #ifdef INET 1343 case AF_INET: 1344 inp = sotoinpcb(so); 1345 tp = intotcpcb(inp); 1346 break; 1347 #endif 1348 #ifdef INET6 1349 case AF_INET6: 1350 in6p = sotoin6pcb(so); 1351 tp = in6totcpcb(in6p); 1352 break; 1353 #endif 1354 } 1355 if (tp == NULL) 1356 goto badsyn; /*XXX*/ 1357 tiwin <<= tp->snd_scale; 1358 goto after_listen; 1359 } 1360 } else { 1361 /* 1362 * None of RST, SYN or ACK was set. 1363 * This is an invalid packet for a 1364 * TCB in LISTEN state. Send a RST. 1365 */ 1366 goto badsyn; 1367 } 1368 } else { 1369 /* 1370 * Received a SYN. 1371 */ 1372 1373 #ifdef INET6 1374 /* 1375 * If deprecated address is forbidden, we do 1376 * not accept SYN to deprecated interface 1377 * address to prevent any new inbound 1378 * connection from getting established. 1379 * When we do not accept SYN, we send a TCP 1380 * RST, with deprecated source address (instead 1381 * of dropping it). We compromise it as it is 1382 * much better for peer to send a RST, and 1383 * RST will be the final packet for the 1384 * exchange. 1385 * 1386 * If we do not forbid deprecated addresses, we 1387 * accept the SYN packet. RFC2462 does not 1388 * suggest dropping SYN in this case. 1389 * If we decipher RFC2462 5.5.4, it says like 1390 * this: 1391 * 1. use of deprecated addr with existing 1392 * communication is okay - "SHOULD continue 1393 * to be used" 1394 * 2. use of it with new communication: 1395 * (2a) "SHOULD NOT be used if alternate 1396 * address with sufficient scope is 1397 * available" 1398 * (2b) nothing mentioned otherwise. 1399 * Here we fall into (2b) case as we have no 1400 * choice in our source address selection - we 1401 * must obey the peer. 1402 * 1403 * The wording in RFC2462 is confusing, and 1404 * there are multiple description text for 1405 * deprecated address handling - worse, they 1406 * are not exactly the same. I believe 5.5.4 1407 * is the best one, so we follow 5.5.4. 1408 */ 1409 if (af == AF_INET6 && !ip6_use_deprecated) { 1410 struct in6_ifaddr *ia6; 1411 if ((ia6 = in6ifa_ifpwithaddr(m->m_pkthdr.rcvif, 1412 &ip6->ip6_dst)) && 1413 (ia6->ia6_flags & IN6_IFF_DEPRECATED)) { 1414 tp = NULL; 1415 goto dropwithreset; 1416 } 1417 } 1418 #endif 1419 1420 /* 1421 * LISTEN socket received a SYN 1422 * from itself? This can't possibly 1423 * be valid; drop the packet. 1424 */ 1425 if (th->th_sport == th->th_dport) { 1426 int i; 1427 1428 switch (af) { 1429 #ifdef INET 1430 case AF_INET: 1431 i = in_hosteq(ip->ip_src, ip->ip_dst); 1432 break; 1433 #endif 1434 #ifdef INET6 1435 case AF_INET6: 1436 i = IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &ip6->ip6_dst); 1437 break; 1438 #endif 1439 default: 1440 i = 1; 1441 } 1442 if (i) { 1443 tcpstat.tcps_badsyn++; 1444 goto drop; 1445 } 1446 } 1447 1448 /* 1449 * SYN looks ok; create compressed TCP 1450 * state for it. 1451 */ 1452 if (so->so_qlen <= so->so_qlimit && 1453 syn_cache_add(&src.sa, &dst.sa, th, tlen, 1454 so, m, optp, optlen, &opti)) 1455 m = NULL; 1456 } 1457 goto drop; 1458 } 1459 } 1460 1461 after_listen: 1462 #ifdef DIAGNOSTIC 1463 /* 1464 * Should not happen now that all embryonic connections 1465 * are handled with compressed state. 1466 */ 1467 if (tp->t_state == TCPS_LISTEN) 1468 panic("tcp_input: TCPS_LISTEN"); 1469 #endif 1470 1471 /* 1472 * Segment received on connection. 1473 * Reset idle time and keep-alive timer. 1474 */ 1475 tp->t_rcvtime = tcp_now; 1476 if (TCPS_HAVEESTABLISHED(tp->t_state)) 1477 TCP_TIMER_ARM(tp, TCPT_KEEP, tcp_keepidle); 1478 1479 /* 1480 * Process options. 1481 */ 1482 if (optp) 1483 tcp_dooptions(tp, optp, optlen, th, &opti); 1484 1485 /* 1486 * Header prediction: check for the two common cases 1487 * of a uni-directional data xfer. If the packet has 1488 * no control flags, is in-sequence, the window didn't 1489 * change and we're not retransmitting, it's a 1490 * candidate. If the length is zero and the ack moved 1491 * forward, we're the sender side of the xfer. Just 1492 * free the data acked & wake any higher level process 1493 * that was blocked waiting for space. If the length 1494 * is non-zero and the ack didn't move, we're the 1495 * receiver side. If we're getting packets in-order 1496 * (the reassembly queue is empty), add the data to 1497 * the socket buffer and note that we need a delayed ack. 1498 */ 1499 if (tp->t_state == TCPS_ESTABLISHED && 1500 (tiflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK && 1501 (!opti.ts_present || TSTMP_GEQ(opti.ts_val, tp->ts_recent)) && 1502 th->th_seq == tp->rcv_nxt && 1503 tiwin && tiwin == tp->snd_wnd && 1504 tp->snd_nxt == tp->snd_max) { 1505 1506 /* 1507 * If last ACK falls within this segment's sequence numbers, 1508 * record the timestamp. 1509 */ 1510 if (opti.ts_present && 1511 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 1512 SEQ_LT(tp->last_ack_sent, th->th_seq + tlen)) { 1513 tp->ts_recent_age = TCP_TIMESTAMP(tp); 1514 tp->ts_recent = opti.ts_val; 1515 } 1516 1517 if (tlen == 0) { 1518 if (SEQ_GT(th->th_ack, tp->snd_una) && 1519 SEQ_LEQ(th->th_ack, tp->snd_max) && 1520 tp->snd_cwnd >= tp->snd_wnd && 1521 tp->t_dupacks < tcprexmtthresh) { 1522 /* 1523 * this is a pure ack for outstanding data. 1524 */ 1525 ++tcpstat.tcps_predack; 1526 if (opti.ts_present && opti.ts_ecr) 1527 tcp_xmit_timer(tp, 1528 TCP_TIMESTAMP(tp) - opti.ts_ecr + 1); 1529 else if (tp->t_rtttime && 1530 SEQ_GT(th->th_ack, tp->t_rtseq)) 1531 tcp_xmit_timer(tp, 1532 tcp_now - tp->t_rtttime); 1533 acked = th->th_ack - tp->snd_una; 1534 tcpstat.tcps_rcvackpack++; 1535 tcpstat.tcps_rcvackbyte += acked; 1536 ND6_HINT(tp); 1537 sbdrop(&so->so_snd, acked); 1538 /* 1539 * We want snd_recover to track snd_una to 1540 * avoid sequence wraparound problems for 1541 * very large transfers. 1542 */ 1543 tp->snd_una = tp->snd_recover = th->th_ack; 1544 m_freem(m); 1545 1546 /* 1547 * If all outstanding data are acked, stop 1548 * retransmit timer, otherwise restart timer 1549 * using current (possibly backed-off) value. 1550 * If process is waiting for space, 1551 * wakeup/selwakeup/signal. If data 1552 * are ready to send, let tcp_output 1553 * decide between more output or persist. 1554 */ 1555 if (tp->snd_una == tp->snd_max) 1556 TCP_TIMER_DISARM(tp, TCPT_REXMT); 1557 else if (TCP_TIMER_ISARMED(tp, 1558 TCPT_PERSIST) == 0) 1559 TCP_TIMER_ARM(tp, TCPT_REXMT, 1560 tp->t_rxtcur); 1561 1562 sowwakeup(so); 1563 if (so->so_snd.sb_cc) 1564 (void) tcp_output(tp); 1565 if (tcp_saveti) 1566 m_freem(tcp_saveti); 1567 return; 1568 } 1569 } else if (th->th_ack == tp->snd_una && 1570 TAILQ_FIRST(&tp->segq) == NULL && 1571 tlen <= sbspace(&so->so_rcv)) { 1572 /* 1573 * this is a pure, in-sequence data packet 1574 * with nothing on the reassembly queue and 1575 * we have enough buffer space to take it. 1576 */ 1577 ++tcpstat.tcps_preddat; 1578 tp->rcv_nxt += tlen; 1579 tcpstat.tcps_rcvpack++; 1580 tcpstat.tcps_rcvbyte += tlen; 1581 ND6_HINT(tp); 1582 /* 1583 * Drop TCP, IP headers and TCP options then add data 1584 * to socket buffer. 1585 */ 1586 if (so->so_state & SS_CANTRCVMORE) 1587 m_freem(m); 1588 else { 1589 m_adj(m, toff + off); 1590 sbappendstream(&so->so_rcv, m); 1591 } 1592 sorwakeup(so); 1593 TCP_SETUP_ACK(tp, th); 1594 if (tp->t_flags & TF_ACKNOW) 1595 (void) tcp_output(tp); 1596 if (tcp_saveti) 1597 m_freem(tcp_saveti); 1598 return; 1599 } 1600 } 1601 1602 /* 1603 * Compute mbuf offset to TCP data segment. 1604 */ 1605 hdroptlen = toff + off; 1606 1607 /* 1608 * Calculate amount of space in receive window, 1609 * and then do TCP input processing. 1610 * Receive window is amount of space in rcv queue, 1611 * but not less than advertised window. 1612 */ 1613 { int win; 1614 1615 win = sbspace(&so->so_rcv); 1616 if (win < 0) 1617 win = 0; 1618 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 1619 } 1620 1621 switch (tp->t_state) { 1622 case TCPS_LISTEN: 1623 /* 1624 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN 1625 */ 1626 if (m->m_flags & (M_BCAST|M_MCAST)) 1627 goto drop; 1628 switch (af) { 1629 #ifdef INET6 1630 case AF_INET6: 1631 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) 1632 goto drop; 1633 break; 1634 #endif /* INET6 */ 1635 case AF_INET: 1636 if (IN_MULTICAST(ip->ip_dst.s_addr) || 1637 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 1638 goto drop; 1639 break; 1640 } 1641 break; 1642 1643 /* 1644 * If the state is SYN_SENT: 1645 * if seg contains an ACK, but not for our SYN, drop the input. 1646 * if seg contains a RST, then drop the connection. 1647 * if seg does not contain SYN, then drop it. 1648 * Otherwise this is an acceptable SYN segment 1649 * initialize tp->rcv_nxt and tp->irs 1650 * if seg contains ack then advance tp->snd_una 1651 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 1652 * arrange for segment to be acked (eventually) 1653 * continue processing rest of data/controls, beginning with URG 1654 */ 1655 case TCPS_SYN_SENT: 1656 if ((tiflags & TH_ACK) && 1657 (SEQ_LEQ(th->th_ack, tp->iss) || 1658 SEQ_GT(th->th_ack, tp->snd_max))) 1659 goto dropwithreset; 1660 if (tiflags & TH_RST) { 1661 if (tiflags & TH_ACK) 1662 tp = tcp_drop(tp, ECONNREFUSED); 1663 goto drop; 1664 } 1665 if ((tiflags & TH_SYN) == 0) 1666 goto drop; 1667 if (tiflags & TH_ACK) { 1668 tp->snd_una = tp->snd_recover = th->th_ack; 1669 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 1670 tp->snd_nxt = tp->snd_una; 1671 TCP_TIMER_DISARM(tp, TCPT_REXMT); 1672 } 1673 tp->irs = th->th_seq; 1674 tcp_rcvseqinit(tp); 1675 tp->t_flags |= TF_ACKNOW; 1676 tcp_mss_from_peer(tp, opti.maxseg); 1677 1678 /* 1679 * Initialize the initial congestion window. If we 1680 * had to retransmit the SYN, we must initialize cwnd 1681 * to 1 segment (i.e. the Loss Window). 1682 */ 1683 if (tp->t_flags & TF_SYN_REXMT) 1684 tp->snd_cwnd = tp->t_peermss; 1685 else 1686 tp->snd_cwnd = TCP_INITIAL_WINDOW(tcp_init_win, 1687 tp->t_peermss); 1688 1689 tcp_rmx_rtt(tp); 1690 if (tiflags & TH_ACK) { 1691 tcpstat.tcps_connects++; 1692 soisconnected(so); 1693 tcp_established(tp); 1694 /* Do window scaling on this connection? */ 1695 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 1696 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 1697 tp->snd_scale = tp->requested_s_scale; 1698 tp->rcv_scale = tp->request_r_scale; 1699 } 1700 TCP_REASS_LOCK(tp); 1701 (void) tcp_reass(tp, NULL, (struct mbuf *)0, &tlen); 1702 TCP_REASS_UNLOCK(tp); 1703 /* 1704 * if we didn't have to retransmit the SYN, 1705 * use its rtt as our initial srtt & rtt var. 1706 */ 1707 if (tp->t_rtttime) 1708 tcp_xmit_timer(tp, tcp_now - tp->t_rtttime); 1709 } else 1710 tp->t_state = TCPS_SYN_RECEIVED; 1711 1712 /* 1713 * Advance th->th_seq to correspond to first data byte. 1714 * If data, trim to stay within window, 1715 * dropping FIN if necessary. 1716 */ 1717 th->th_seq++; 1718 if (tlen > tp->rcv_wnd) { 1719 todrop = tlen - tp->rcv_wnd; 1720 m_adj(m, -todrop); 1721 tlen = tp->rcv_wnd; 1722 tiflags &= ~TH_FIN; 1723 tcpstat.tcps_rcvpackafterwin++; 1724 tcpstat.tcps_rcvbyteafterwin += todrop; 1725 } 1726 tp->snd_wl1 = th->th_seq - 1; 1727 tp->rcv_up = th->th_seq; 1728 goto step6; 1729 1730 /* 1731 * If the state is SYN_RECEIVED: 1732 * If seg contains an ACK, but not for our SYN, drop the input 1733 * and generate an RST. See page 36, rfc793 1734 */ 1735 case TCPS_SYN_RECEIVED: 1736 if ((tiflags & TH_ACK) && 1737 (SEQ_LEQ(th->th_ack, tp->iss) || 1738 SEQ_GT(th->th_ack, tp->snd_max))) 1739 goto dropwithreset; 1740 break; 1741 } 1742 1743 /* 1744 * States other than LISTEN or SYN_SENT. 1745 * First check timestamp, if present. 1746 * Then check that at least some bytes of segment are within 1747 * receive window. If segment begins before rcv_nxt, 1748 * drop leading data (and SYN); if nothing left, just ack. 1749 * 1750 * RFC 1323 PAWS: If we have a timestamp reply on this segment 1751 * and it's less than ts_recent, drop it. 1752 */ 1753 if (opti.ts_present && (tiflags & TH_RST) == 0 && tp->ts_recent && 1754 TSTMP_LT(opti.ts_val, tp->ts_recent)) { 1755 1756 /* Check to see if ts_recent is over 24 days old. */ 1757 if ((int)(TCP_TIMESTAMP(tp) - tp->ts_recent_age) > 1758 TCP_PAWS_IDLE) { 1759 /* 1760 * Invalidate ts_recent. If this segment updates 1761 * ts_recent, the age will be reset later and ts_recent 1762 * will get a valid value. If it does not, setting 1763 * ts_recent to zero will at least satisfy the 1764 * requirement that zero be placed in the timestamp 1765 * echo reply when ts_recent isn't valid. The 1766 * age isn't reset until we get a valid ts_recent 1767 * because we don't want out-of-order segments to be 1768 * dropped when ts_recent is old. 1769 */ 1770 tp->ts_recent = 0; 1771 } else { 1772 tcpstat.tcps_rcvduppack++; 1773 tcpstat.tcps_rcvdupbyte += tlen; 1774 tcpstat.tcps_pawsdrop++; 1775 goto dropafterack; 1776 } 1777 } 1778 1779 todrop = tp->rcv_nxt - th->th_seq; 1780 if (todrop > 0) { 1781 if (tiflags & TH_SYN) { 1782 tiflags &= ~TH_SYN; 1783 th->th_seq++; 1784 if (th->th_urp > 1) 1785 th->th_urp--; 1786 else { 1787 tiflags &= ~TH_URG; 1788 th->th_urp = 0; 1789 } 1790 todrop--; 1791 } 1792 if (todrop > tlen || 1793 (todrop == tlen && (tiflags & TH_FIN) == 0)) { 1794 /* 1795 * Any valid FIN must be to the left of the window. 1796 * At this point the FIN must be a duplicate or 1797 * out of sequence; drop it. 1798 */ 1799 tiflags &= ~TH_FIN; 1800 /* 1801 * Send an ACK to resynchronize and drop any data. 1802 * But keep on processing for RST or ACK. 1803 */ 1804 tp->t_flags |= TF_ACKNOW; 1805 todrop = tlen; 1806 tcpstat.tcps_rcvdupbyte += todrop; 1807 tcpstat.tcps_rcvduppack++; 1808 } else { 1809 tcpstat.tcps_rcvpartduppack++; 1810 tcpstat.tcps_rcvpartdupbyte += todrop; 1811 } 1812 hdroptlen += todrop; /*drop from head afterwards*/ 1813 th->th_seq += todrop; 1814 tlen -= todrop; 1815 if (th->th_urp > todrop) 1816 th->th_urp -= todrop; 1817 else { 1818 tiflags &= ~TH_URG; 1819 th->th_urp = 0; 1820 } 1821 } 1822 1823 /* 1824 * If new data are received on a connection after the 1825 * user processes are gone, then RST the other end. 1826 */ 1827 if ((so->so_state & SS_NOFDREF) && 1828 tp->t_state > TCPS_CLOSE_WAIT && tlen) { 1829 tp = tcp_close(tp); 1830 tcpstat.tcps_rcvafterclose++; 1831 goto dropwithreset; 1832 } 1833 1834 /* 1835 * If segment ends after window, drop trailing data 1836 * (and PUSH and FIN); if nothing left, just ACK. 1837 */ 1838 todrop = (th->th_seq + tlen) - (tp->rcv_nxt+tp->rcv_wnd); 1839 if (todrop > 0) { 1840 tcpstat.tcps_rcvpackafterwin++; 1841 if (todrop >= tlen) { 1842 tcpstat.tcps_rcvbyteafterwin += tlen; 1843 /* 1844 * If a new connection request is received 1845 * while in TIME_WAIT, drop the old connection 1846 * and start over if the sequence numbers 1847 * are above the previous ones. 1848 * 1849 * NOTE: We will checksum the packet again, and 1850 * so we need to put the header fields back into 1851 * network order! 1852 * XXX This kind of sucks, but we don't expect 1853 * XXX this to happen very often, so maybe it 1854 * XXX doesn't matter so much. 1855 */ 1856 if (tiflags & TH_SYN && 1857 tp->t_state == TCPS_TIME_WAIT && 1858 SEQ_GT(th->th_seq, tp->rcv_nxt)) { 1859 iss = tcp_new_iss(tp, tp->snd_nxt); 1860 tp = tcp_close(tp); 1861 TCP_FIELDS_TO_NET(th); 1862 goto findpcb; 1863 } 1864 /* 1865 * If window is closed can only take segments at 1866 * window edge, and have to drop data and PUSH from 1867 * incoming segments. Continue processing, but 1868 * remember to ack. Otherwise, drop segment 1869 * and ack. 1870 */ 1871 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 1872 tp->t_flags |= TF_ACKNOW; 1873 tcpstat.tcps_rcvwinprobe++; 1874 } else 1875 goto dropafterack; 1876 } else 1877 tcpstat.tcps_rcvbyteafterwin += todrop; 1878 m_adj(m, -todrop); 1879 tlen -= todrop; 1880 tiflags &= ~(TH_PUSH|TH_FIN); 1881 } 1882 1883 /* 1884 * If last ACK falls within this segment's sequence numbers, 1885 * and the timestamp is newer, record it. 1886 */ 1887 if (opti.ts_present && TSTMP_GEQ(opti.ts_val, tp->ts_recent) && 1888 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 1889 SEQ_LT(tp->last_ack_sent, th->th_seq + tlen + 1890 ((tiflags & (TH_SYN|TH_FIN)) != 0))) { 1891 tp->ts_recent_age = TCP_TIMESTAMP(tp); 1892 tp->ts_recent = opti.ts_val; 1893 } 1894 1895 /* 1896 * If the RST bit is set examine the state: 1897 * SYN_RECEIVED STATE: 1898 * If passive open, return to LISTEN state. 1899 * If active open, inform user that connection was refused. 1900 * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES: 1901 * Inform user that connection was reset, and close tcb. 1902 * CLOSING, LAST_ACK, TIME_WAIT STATES 1903 * Close the tcb. 1904 */ 1905 if (tiflags&TH_RST) switch (tp->t_state) { 1906 1907 case TCPS_SYN_RECEIVED: 1908 so->so_error = ECONNREFUSED; 1909 goto close; 1910 1911 case TCPS_ESTABLISHED: 1912 case TCPS_FIN_WAIT_1: 1913 case TCPS_FIN_WAIT_2: 1914 case TCPS_CLOSE_WAIT: 1915 so->so_error = ECONNRESET; 1916 close: 1917 tp->t_state = TCPS_CLOSED; 1918 tcpstat.tcps_drops++; 1919 tp = tcp_close(tp); 1920 goto drop; 1921 1922 case TCPS_CLOSING: 1923 case TCPS_LAST_ACK: 1924 case TCPS_TIME_WAIT: 1925 tp = tcp_close(tp); 1926 goto drop; 1927 } 1928 1929 /* 1930 * If a SYN is in the window, then this is an 1931 * error and we send an RST and drop the connection. 1932 */ 1933 if (tiflags & TH_SYN) { 1934 tp = tcp_drop(tp, ECONNRESET); 1935 goto dropwithreset; 1936 } 1937 1938 /* 1939 * If the ACK bit is off we drop the segment and return. 1940 */ 1941 if ((tiflags & TH_ACK) == 0) { 1942 if (tp->t_flags & TF_ACKNOW) 1943 goto dropafterack; 1944 else 1945 goto drop; 1946 } 1947 1948 /* 1949 * Ack processing. 1950 */ 1951 switch (tp->t_state) { 1952 1953 /* 1954 * In SYN_RECEIVED state if the ack ACKs our SYN then enter 1955 * ESTABLISHED state and continue processing, otherwise 1956 * send an RST. 1957 */ 1958 case TCPS_SYN_RECEIVED: 1959 if (SEQ_GT(tp->snd_una, th->th_ack) || 1960 SEQ_GT(th->th_ack, tp->snd_max)) 1961 goto dropwithreset; 1962 tcpstat.tcps_connects++; 1963 soisconnected(so); 1964 tcp_established(tp); 1965 /* Do window scaling? */ 1966 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 1967 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 1968 tp->snd_scale = tp->requested_s_scale; 1969 tp->rcv_scale = tp->request_r_scale; 1970 } 1971 TCP_REASS_LOCK(tp); 1972 (void) tcp_reass(tp, NULL, (struct mbuf *)0, &tlen); 1973 TCP_REASS_UNLOCK(tp); 1974 tp->snd_wl1 = th->th_seq - 1; 1975 /* fall into ... */ 1976 1977 /* 1978 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 1979 * ACKs. If the ack is in the range 1980 * tp->snd_una < th->th_ack <= tp->snd_max 1981 * then advance tp->snd_una to th->th_ack and drop 1982 * data from the retransmission queue. If this ACK reflects 1983 * more up to date window information we update our window information. 1984 */ 1985 case TCPS_ESTABLISHED: 1986 case TCPS_FIN_WAIT_1: 1987 case TCPS_FIN_WAIT_2: 1988 case TCPS_CLOSE_WAIT: 1989 case TCPS_CLOSING: 1990 case TCPS_LAST_ACK: 1991 case TCPS_TIME_WAIT: 1992 1993 if (SEQ_LEQ(th->th_ack, tp->snd_una)) { 1994 if (tlen == 0 && tiwin == tp->snd_wnd) { 1995 tcpstat.tcps_rcvdupack++; 1996 /* 1997 * If we have outstanding data (other than 1998 * a window probe), this is a completely 1999 * duplicate ack (ie, window info didn't 2000 * change), the ack is the biggest we've 2001 * seen and we've seen exactly our rexmt 2002 * threshhold of them, assume a packet 2003 * has been dropped and retransmit it. 2004 * Kludge snd_nxt & the congestion 2005 * window so we send only this one 2006 * packet. 2007 * 2008 * We know we're losing at the current 2009 * window size so do congestion avoidance 2010 * (set ssthresh to half the current window 2011 * and pull our congestion window back to 2012 * the new ssthresh). 2013 * 2014 * Dup acks mean that packets have left the 2015 * network (they're now cached at the receiver) 2016 * so bump cwnd by the amount in the receiver 2017 * to keep a constant cwnd packets in the 2018 * network. 2019 */ 2020 if (TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 || 2021 th->th_ack != tp->snd_una) 2022 tp->t_dupacks = 0; 2023 else if (++tp->t_dupacks == tcprexmtthresh) { 2024 tcp_seq onxt = tp->snd_nxt; 2025 u_int win = 2026 min(tp->snd_wnd, tp->snd_cwnd) / 2027 2 / tp->t_segsz; 2028 if (tcp_do_newreno && SEQ_LT(th->th_ack, 2029 tp->snd_recover)) { 2030 /* 2031 * False fast retransmit after 2032 * timeout. Do not cut window. 2033 */ 2034 tp->snd_cwnd += tp->t_segsz; 2035 tp->t_dupacks = 0; 2036 (void) tcp_output(tp); 2037 goto drop; 2038 } 2039 2040 if (win < 2) 2041 win = 2; 2042 tp->snd_ssthresh = win * tp->t_segsz; 2043 tp->snd_recover = tp->snd_max; 2044 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2045 tp->t_rtttime = 0; 2046 tp->snd_nxt = th->th_ack; 2047 tp->snd_cwnd = tp->t_segsz; 2048 (void) tcp_output(tp); 2049 tp->snd_cwnd = tp->snd_ssthresh + 2050 tp->t_segsz * tp->t_dupacks; 2051 if (SEQ_GT(onxt, tp->snd_nxt)) 2052 tp->snd_nxt = onxt; 2053 goto drop; 2054 } else if (tp->t_dupacks > tcprexmtthresh) { 2055 tp->snd_cwnd += tp->t_segsz; 2056 (void) tcp_output(tp); 2057 goto drop; 2058 } 2059 } else 2060 tp->t_dupacks = 0; 2061 break; 2062 } 2063 /* 2064 * If the congestion window was inflated to account 2065 * for the other side's cached packets, retract it. 2066 */ 2067 if (tcp_do_newreno == 0) { 2068 if (tp->t_dupacks >= tcprexmtthresh && 2069 tp->snd_cwnd > tp->snd_ssthresh) 2070 tp->snd_cwnd = tp->snd_ssthresh; 2071 tp->t_dupacks = 0; 2072 } else if (tp->t_dupacks >= tcprexmtthresh && 2073 tcp_newreno(tp, th) == 0) { 2074 tp->snd_cwnd = tp->snd_ssthresh; 2075 /* 2076 * Window inflation should have left us with approx. 2077 * snd_ssthresh outstanding data. But in case we 2078 * would be inclined to send a burst, better to do 2079 * it via the slow start mechanism. 2080 */ 2081 if (SEQ_SUB(tp->snd_max, th->th_ack) < tp->snd_ssthresh) 2082 tp->snd_cwnd = SEQ_SUB(tp->snd_max, th->th_ack) 2083 + tp->t_segsz; 2084 tp->t_dupacks = 0; 2085 } 2086 if (SEQ_GT(th->th_ack, tp->snd_max)) { 2087 tcpstat.tcps_rcvacktoomuch++; 2088 goto dropafterack; 2089 } 2090 acked = th->th_ack - tp->snd_una; 2091 tcpstat.tcps_rcvackpack++; 2092 tcpstat.tcps_rcvackbyte += acked; 2093 2094 /* 2095 * If we have a timestamp reply, update smoothed 2096 * round trip time. If no timestamp is present but 2097 * transmit timer is running and timed sequence 2098 * number was acked, update smoothed round trip time. 2099 * Since we now have an rtt measurement, cancel the 2100 * timer backoff (cf., Phil Karn's retransmit alg.). 2101 * Recompute the initial retransmit timer. 2102 */ 2103 if (opti.ts_present && opti.ts_ecr) 2104 tcp_xmit_timer(tp, TCP_TIMESTAMP(tp) - opti.ts_ecr + 1); 2105 else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) 2106 tcp_xmit_timer(tp, tcp_now - tp->t_rtttime); 2107 2108 /* 2109 * If all outstanding data is acked, stop retransmit 2110 * timer and remember to restart (more output or persist). 2111 * If there is more data to be acked, restart retransmit 2112 * timer, using current (possibly backed-off) value. 2113 */ 2114 if (th->th_ack == tp->snd_max) { 2115 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2116 needoutput = 1; 2117 } else if (TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) 2118 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 2119 /* 2120 * When new data is acked, open the congestion window. 2121 * If the window gives us less than ssthresh packets 2122 * in flight, open exponentially (segsz per packet). 2123 * Otherwise open linearly: segsz per window 2124 * (segsz^2 / cwnd per packet), plus a constant 2125 * fraction of a packet (segsz/8) to help larger windows 2126 * open quickly enough. 2127 */ 2128 { 2129 u_int cw = tp->snd_cwnd; 2130 u_int incr = tp->t_segsz; 2131 2132 if (cw > tp->snd_ssthresh) 2133 incr = incr * incr / cw; 2134 if (tcp_do_newreno == 0 || SEQ_GEQ(th->th_ack, tp->snd_recover)) 2135 tp->snd_cwnd = min(cw + incr, 2136 TCP_MAXWIN << tp->snd_scale); 2137 } 2138 ND6_HINT(tp); 2139 if (acked > so->so_snd.sb_cc) { 2140 tp->snd_wnd -= so->so_snd.sb_cc; 2141 sbdrop(&so->so_snd, (int)so->so_snd.sb_cc); 2142 ourfinisacked = 1; 2143 } else { 2144 sbdrop(&so->so_snd, acked); 2145 tp->snd_wnd -= acked; 2146 ourfinisacked = 0; 2147 } 2148 sowwakeup(so); 2149 /* 2150 * We want snd_recover to track snd_una to 2151 * avoid sequence wraparound problems for 2152 * very large transfers. 2153 */ 2154 tp->snd_una = tp->snd_recover = th->th_ack; 2155 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2156 tp->snd_nxt = tp->snd_una; 2157 2158 switch (tp->t_state) { 2159 2160 /* 2161 * In FIN_WAIT_1 STATE in addition to the processing 2162 * for the ESTABLISHED state if our FIN is now acknowledged 2163 * then enter FIN_WAIT_2. 2164 */ 2165 case TCPS_FIN_WAIT_1: 2166 if (ourfinisacked) { 2167 /* 2168 * If we can't receive any more 2169 * data, then closing user can proceed. 2170 * Starting the timer is contrary to the 2171 * specification, but if we don't get a FIN 2172 * we'll hang forever. 2173 */ 2174 if (so->so_state & SS_CANTRCVMORE) { 2175 soisdisconnected(so); 2176 if (tcp_maxidle > 0) 2177 TCP_TIMER_ARM(tp, TCPT_2MSL, 2178 tcp_maxidle); 2179 } 2180 tp->t_state = TCPS_FIN_WAIT_2; 2181 } 2182 break; 2183 2184 /* 2185 * In CLOSING STATE in addition to the processing for 2186 * the ESTABLISHED state if the ACK acknowledges our FIN 2187 * then enter the TIME-WAIT state, otherwise ignore 2188 * the segment. 2189 */ 2190 case TCPS_CLOSING: 2191 if (ourfinisacked) { 2192 tp->t_state = TCPS_TIME_WAIT; 2193 tcp_canceltimers(tp); 2194 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 2195 soisdisconnected(so); 2196 } 2197 break; 2198 2199 /* 2200 * In LAST_ACK, we may still be waiting for data to drain 2201 * and/or to be acked, as well as for the ack of our FIN. 2202 * If our FIN is now acknowledged, delete the TCB, 2203 * enter the closed state and return. 2204 */ 2205 case TCPS_LAST_ACK: 2206 if (ourfinisacked) { 2207 tp = tcp_close(tp); 2208 goto drop; 2209 } 2210 break; 2211 2212 /* 2213 * In TIME_WAIT state the only thing that should arrive 2214 * is a retransmission of the remote FIN. Acknowledge 2215 * it and restart the finack timer. 2216 */ 2217 case TCPS_TIME_WAIT: 2218 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 2219 goto dropafterack; 2220 } 2221 } 2222 2223 step6: 2224 /* 2225 * Update window information. 2226 * Don't look at window if no ACK: TAC's send garbage on first SYN. 2227 */ 2228 if ((tiflags & TH_ACK) && (SEQ_LT(tp->snd_wl1, th->th_seq) || 2229 (tp->snd_wl1 == th->th_seq && SEQ_LT(tp->snd_wl2, th->th_ack)) || 2230 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))) { 2231 /* keep track of pure window updates */ 2232 if (tlen == 0 && 2233 tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) 2234 tcpstat.tcps_rcvwinupd++; 2235 tp->snd_wnd = tiwin; 2236 tp->snd_wl1 = th->th_seq; 2237 tp->snd_wl2 = th->th_ack; 2238 if (tp->snd_wnd > tp->max_sndwnd) 2239 tp->max_sndwnd = tp->snd_wnd; 2240 needoutput = 1; 2241 } 2242 2243 /* 2244 * Process segments with URG. 2245 */ 2246 if ((tiflags & TH_URG) && th->th_urp && 2247 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2248 /* 2249 * This is a kludge, but if we receive and accept 2250 * random urgent pointers, we'll crash in 2251 * soreceive. It's hard to imagine someone 2252 * actually wanting to send this much urgent data. 2253 */ 2254 if (th->th_urp + so->so_rcv.sb_cc > sb_max) { 2255 th->th_urp = 0; /* XXX */ 2256 tiflags &= ~TH_URG; /* XXX */ 2257 goto dodata; /* XXX */ 2258 } 2259 /* 2260 * If this segment advances the known urgent pointer, 2261 * then mark the data stream. This should not happen 2262 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 2263 * a FIN has been received from the remote side. 2264 * In these states we ignore the URG. 2265 * 2266 * According to RFC961 (Assigned Protocols), 2267 * the urgent pointer points to the last octet 2268 * of urgent data. We continue, however, 2269 * to consider it to indicate the first octet 2270 * of data past the urgent section as the original 2271 * spec states (in one of two places). 2272 */ 2273 if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) { 2274 tp->rcv_up = th->th_seq + th->th_urp; 2275 so->so_oobmark = so->so_rcv.sb_cc + 2276 (tp->rcv_up - tp->rcv_nxt) - 1; 2277 if (so->so_oobmark == 0) 2278 so->so_state |= SS_RCVATMARK; 2279 sohasoutofband(so); 2280 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); 2281 } 2282 /* 2283 * Remove out of band data so doesn't get presented to user. 2284 * This can happen independent of advancing the URG pointer, 2285 * but if two URG's are pending at once, some out-of-band 2286 * data may creep in... ick. 2287 */ 2288 if (th->th_urp <= (u_int16_t) tlen 2289 #ifdef SO_OOBINLINE 2290 && (so->so_options & SO_OOBINLINE) == 0 2291 #endif 2292 ) 2293 tcp_pulloutofband(so, th, m, hdroptlen); 2294 } else 2295 /* 2296 * If no out of band data is expected, 2297 * pull receive urgent pointer along 2298 * with the receive window. 2299 */ 2300 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) 2301 tp->rcv_up = tp->rcv_nxt; 2302 dodata: /* XXX */ 2303 2304 /* 2305 * Process the segment text, merging it into the TCP sequencing queue, 2306 * and arranging for acknowledgement of receipt if necessary. 2307 * This process logically involves adjusting tp->rcv_wnd as data 2308 * is presented to the user (this happens in tcp_usrreq.c, 2309 * case PRU_RCVD). If a FIN has already been received on this 2310 * connection then we just ignore the text. 2311 */ 2312 if ((tlen || (tiflags & TH_FIN)) && 2313 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2314 /* 2315 * Insert segment ti into reassembly queue of tcp with 2316 * control block tp. Return TH_FIN if reassembly now includes 2317 * a segment with FIN. The macro form does the common case 2318 * inline (segment is the next to be received on an 2319 * established connection, and the queue is empty), 2320 * avoiding linkage into and removal from the queue and 2321 * repetition of various conversions. 2322 * Set DELACK for segments received in order, but ack 2323 * immediately when segments are out of order 2324 * (so fast retransmit can work). 2325 */ 2326 /* NOTE: this was TCP_REASS() macro, but used only once */ 2327 TCP_REASS_LOCK(tp); 2328 if (th->th_seq == tp->rcv_nxt && 2329 TAILQ_FIRST(&tp->segq) == NULL && 2330 tp->t_state == TCPS_ESTABLISHED) { 2331 TCP_SETUP_ACK(tp, th); 2332 tp->rcv_nxt += tlen; 2333 tiflags = th->th_flags & TH_FIN; 2334 tcpstat.tcps_rcvpack++; 2335 tcpstat.tcps_rcvbyte += tlen; 2336 ND6_HINT(tp); 2337 if (so->so_state & SS_CANTRCVMORE) 2338 m_freem(m); 2339 else { 2340 m_adj(m, hdroptlen); 2341 sbappendstream(&(so)->so_rcv, m); 2342 } 2343 sorwakeup(so); 2344 } else { 2345 m_adj(m, hdroptlen); 2346 tiflags = tcp_reass(tp, th, m, &tlen); 2347 tp->t_flags |= TF_ACKNOW; 2348 } 2349 TCP_REASS_UNLOCK(tp); 2350 2351 /* 2352 * Note the amount of data that peer has sent into 2353 * our window, in order to estimate the sender's 2354 * buffer size. 2355 */ 2356 len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); 2357 } else { 2358 m_freem(m); 2359 m = NULL; 2360 tiflags &= ~TH_FIN; 2361 } 2362 2363 /* 2364 * If FIN is received ACK the FIN and let the user know 2365 * that the connection is closing. Ignore a FIN received before 2366 * the connection is fully established. 2367 */ 2368 if ((tiflags & TH_FIN) && TCPS_HAVEESTABLISHED(tp->t_state)) { 2369 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2370 socantrcvmore(so); 2371 tp->t_flags |= TF_ACKNOW; 2372 tp->rcv_nxt++; 2373 } 2374 switch (tp->t_state) { 2375 2376 /* 2377 * In ESTABLISHED STATE enter the CLOSE_WAIT state. 2378 */ 2379 case TCPS_ESTABLISHED: 2380 tp->t_state = TCPS_CLOSE_WAIT; 2381 break; 2382 2383 /* 2384 * If still in FIN_WAIT_1 STATE FIN has not been acked so 2385 * enter the CLOSING state. 2386 */ 2387 case TCPS_FIN_WAIT_1: 2388 tp->t_state = TCPS_CLOSING; 2389 break; 2390 2391 /* 2392 * In FIN_WAIT_2 state enter the TIME_WAIT state, 2393 * starting the time-wait timer, turning off the other 2394 * standard timers. 2395 */ 2396 case TCPS_FIN_WAIT_2: 2397 tp->t_state = TCPS_TIME_WAIT; 2398 tcp_canceltimers(tp); 2399 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 2400 soisdisconnected(so); 2401 break; 2402 2403 /* 2404 * In TIME_WAIT state restart the 2 MSL time_wait timer. 2405 */ 2406 case TCPS_TIME_WAIT: 2407 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 2408 break; 2409 } 2410 } 2411 #ifdef TCP_DEBUG 2412 if (so->so_options & SO_DEBUG) 2413 tcp_trace(TA_INPUT, ostate, tp, tcp_saveti, 0); 2414 #endif 2415 2416 /* 2417 * Return any desired output. 2418 */ 2419 if (needoutput || (tp->t_flags & TF_ACKNOW)) 2420 (void) tcp_output(tp); 2421 if (tcp_saveti) 2422 m_freem(tcp_saveti); 2423 return; 2424 2425 badsyn: 2426 /* 2427 * Received a bad SYN. Increment counters and dropwithreset. 2428 */ 2429 tcpstat.tcps_badsyn++; 2430 tp = NULL; 2431 goto dropwithreset; 2432 2433 dropafterack: 2434 /* 2435 * Generate an ACK dropping incoming segment if it occupies 2436 * sequence space, where the ACK reflects our state. 2437 */ 2438 if (tiflags & TH_RST) 2439 goto drop; 2440 m_freem(m); 2441 tp->t_flags |= TF_ACKNOW; 2442 (void) tcp_output(tp); 2443 if (tcp_saveti) 2444 m_freem(tcp_saveti); 2445 return; 2446 2447 dropwithreset_ratelim: 2448 /* 2449 * We may want to rate-limit RSTs in certain situations, 2450 * particularly if we are sending an RST in response to 2451 * an attempt to connect to or otherwise communicate with 2452 * a port for which we have no socket. 2453 */ 2454 if (ppsratecheck(&tcp_rst_ppslim_last, &tcp_rst_ppslim_count, 2455 tcp_rst_ppslim) == 0) { 2456 /* XXX stat */ 2457 goto drop; 2458 } 2459 /* ...fall into dropwithreset... */ 2460 2461 dropwithreset: 2462 /* 2463 * Generate a RST, dropping incoming segment. 2464 * Make ACK acceptable to originator of segment. 2465 */ 2466 if (tiflags & TH_RST) 2467 goto drop; 2468 2469 switch (af) { 2470 #ifdef INET6 2471 case AF_INET6: 2472 /* For following calls to tcp_respond */ 2473 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) 2474 goto drop; 2475 break; 2476 #endif /* INET6 */ 2477 case AF_INET: 2478 if (IN_MULTICAST(ip->ip_dst.s_addr) || 2479 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 2480 goto drop; 2481 } 2482 2483 { 2484 /* 2485 * need to recover version # field, which was overwritten on 2486 * ip_cksum computation. 2487 */ 2488 struct ip *sip; 2489 sip = mtod(m, struct ip *); 2490 switch (af) { 2491 #ifdef INET 2492 case AF_INET: 2493 sip->ip_v = 4; 2494 break; 2495 #endif 2496 #ifdef INET6 2497 case AF_INET6: 2498 sip->ip_v = 6; 2499 break; 2500 #endif 2501 } 2502 } 2503 if (tiflags & TH_ACK) 2504 (void)tcp_respond(tp, m, m, th, (tcp_seq)0, th->th_ack, TH_RST); 2505 else { 2506 if (tiflags & TH_SYN) 2507 tlen++; 2508 (void)tcp_respond(tp, m, m, th, th->th_seq + tlen, (tcp_seq)0, 2509 TH_RST|TH_ACK); 2510 } 2511 if (tcp_saveti) 2512 m_freem(tcp_saveti); 2513 return; 2514 2515 badcsum: 2516 tcpstat.tcps_rcvbadsum++; 2517 drop: 2518 /* 2519 * Drop space held by incoming segment and return. 2520 */ 2521 if (tp) { 2522 if (tp->t_inpcb) 2523 so = tp->t_inpcb->inp_socket; 2524 #ifdef INET6 2525 else if (tp->t_in6pcb) 2526 so = tp->t_in6pcb->in6p_socket; 2527 #endif 2528 else 2529 so = NULL; 2530 #ifdef TCP_DEBUG 2531 if (so && (so->so_options & SO_DEBUG) != 0) 2532 tcp_trace(TA_DROP, ostate, tp, tcp_saveti, 0); 2533 #endif 2534 } 2535 if (tcp_saveti) 2536 m_freem(tcp_saveti); 2537 m_freem(m); 2538 return; 2539 } 2540 2541 void 2542 tcp_dooptions(tp, cp, cnt, th, oi) 2543 struct tcpcb *tp; 2544 u_char *cp; 2545 int cnt; 2546 struct tcphdr *th; 2547 struct tcp_opt_info *oi; 2548 { 2549 u_int16_t mss; 2550 int opt, optlen; 2551 2552 for (; cnt > 0; cnt -= optlen, cp += optlen) { 2553 opt = cp[0]; 2554 if (opt == TCPOPT_EOL) 2555 break; 2556 if (opt == TCPOPT_NOP) 2557 optlen = 1; 2558 else { 2559 if (cnt < 2) 2560 break; 2561 optlen = cp[1]; 2562 if (optlen < 2 || optlen > cnt) 2563 break; 2564 } 2565 switch (opt) { 2566 2567 default: 2568 continue; 2569 2570 case TCPOPT_MAXSEG: 2571 if (optlen != TCPOLEN_MAXSEG) 2572 continue; 2573 if (!(th->th_flags & TH_SYN)) 2574 continue; 2575 bcopy(cp + 2, &mss, sizeof(mss)); 2576 oi->maxseg = ntohs(mss); 2577 break; 2578 2579 case TCPOPT_WINDOW: 2580 if (optlen != TCPOLEN_WINDOW) 2581 continue; 2582 if (!(th->th_flags & TH_SYN)) 2583 continue; 2584 tp->t_flags |= TF_RCVD_SCALE; 2585 tp->requested_s_scale = cp[2]; 2586 if (tp->requested_s_scale > TCP_MAX_WINSHIFT) { 2587 #if 0 /*XXX*/ 2588 char *p; 2589 2590 if (ip) 2591 p = ntohl(ip->ip_src); 2592 #ifdef INET6 2593 else if (ip6) 2594 p = ip6_sprintf(&ip6->ip6_src); 2595 #endif 2596 else 2597 p = "(unknown)"; 2598 log(LOG_ERR, "TCP: invalid wscale %d from %s, " 2599 "assuming %d\n", 2600 tp->requested_s_scale, p, 2601 TCP_MAX_WINSHIFT); 2602 #else 2603 log(LOG_ERR, "TCP: invalid wscale %d, " 2604 "assuming %d\n", 2605 tp->requested_s_scale, 2606 TCP_MAX_WINSHIFT); 2607 #endif 2608 tp->requested_s_scale = TCP_MAX_WINSHIFT; 2609 } 2610 break; 2611 2612 case TCPOPT_TIMESTAMP: 2613 if (optlen != TCPOLEN_TIMESTAMP) 2614 continue; 2615 oi->ts_present = 1; 2616 bcopy(cp + 2, &oi->ts_val, sizeof(oi->ts_val)); 2617 NTOHL(oi->ts_val); 2618 bcopy(cp + 6, &oi->ts_ecr, sizeof(oi->ts_ecr)); 2619 NTOHL(oi->ts_ecr); 2620 2621 /* 2622 * A timestamp received in a SYN makes 2623 * it ok to send timestamp requests and replies. 2624 */ 2625 if (th->th_flags & TH_SYN) { 2626 tp->t_flags |= TF_RCVD_TSTMP; 2627 tp->ts_recent = oi->ts_val; 2628 tp->ts_recent_age = TCP_TIMESTAMP(tp); 2629 } 2630 break; 2631 case TCPOPT_SACK_PERMITTED: 2632 if (optlen != TCPOLEN_SACK_PERMITTED) 2633 continue; 2634 if (!(th->th_flags & TH_SYN)) 2635 continue; 2636 tp->t_flags &= ~TF_CANT_TXSACK; 2637 break; 2638 2639 case TCPOPT_SACK: 2640 if (tp->t_flags & TF_IGNR_RXSACK) 2641 continue; 2642 if (optlen % 8 != 2 || optlen < 10) 2643 continue; 2644 cp += 2; 2645 optlen -= 2; 2646 for (; optlen > 0; cp -= 8, optlen -= 8) { 2647 tcp_seq lwe, rwe; 2648 bcopy((char *)cp, (char *) &lwe, sizeof(lwe)); 2649 NTOHL(lwe); 2650 bcopy((char *)cp, (char *) &rwe, sizeof(rwe)); 2651 NTOHL(rwe); 2652 /* tcp_mark_sacked(tp, lwe, rwe); */ 2653 } 2654 break; 2655 } 2656 } 2657 } 2658 2659 /* 2660 * Pull out of band byte out of a segment so 2661 * it doesn't appear in the user's data queue. 2662 * It is still reflected in the segment length for 2663 * sequencing purposes. 2664 */ 2665 void 2666 tcp_pulloutofband(so, th, m, off) 2667 struct socket *so; 2668 struct tcphdr *th; 2669 struct mbuf *m; 2670 int off; 2671 { 2672 int cnt = off + th->th_urp - 1; 2673 2674 while (cnt >= 0) { 2675 if (m->m_len > cnt) { 2676 char *cp = mtod(m, caddr_t) + cnt; 2677 struct tcpcb *tp = sototcpcb(so); 2678 2679 tp->t_iobc = *cp; 2680 tp->t_oobflags |= TCPOOB_HAVEDATA; 2681 bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); 2682 m->m_len--; 2683 return; 2684 } 2685 cnt -= m->m_len; 2686 m = m->m_next; 2687 if (m == 0) 2688 break; 2689 } 2690 panic("tcp_pulloutofband"); 2691 } 2692 2693 /* 2694 * Collect new round-trip time estimate 2695 * and update averages and current timeout. 2696 */ 2697 void 2698 tcp_xmit_timer(tp, rtt) 2699 struct tcpcb *tp; 2700 uint32_t rtt; 2701 { 2702 int32_t delta; 2703 2704 tcpstat.tcps_rttupdated++; 2705 if (tp->t_srtt != 0) { 2706 /* 2707 * srtt is stored as fixed point with 3 bits after the 2708 * binary point (i.e., scaled by 8). The following magic 2709 * is equivalent to the smoothing algorithm in rfc793 with 2710 * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed 2711 * point). Adjust rtt to origin 0. 2712 */ 2713 delta = (rtt << 2) - (tp->t_srtt >> TCP_RTT_SHIFT); 2714 if ((tp->t_srtt += delta) <= 0) 2715 tp->t_srtt = 1 << 2; 2716 /* 2717 * We accumulate a smoothed rtt variance (actually, a 2718 * smoothed mean difference), then set the retransmit 2719 * timer to smoothed rtt + 4 times the smoothed variance. 2720 * rttvar is stored as fixed point with 2 bits after the 2721 * binary point (scaled by 4). The following is 2722 * equivalent to rfc793 smoothing with an alpha of .75 2723 * (rttvar = rttvar*3/4 + |delta| / 4). This replaces 2724 * rfc793's wired-in beta. 2725 */ 2726 if (delta < 0) 2727 delta = -delta; 2728 delta -= (tp->t_rttvar >> TCP_RTTVAR_SHIFT); 2729 if ((tp->t_rttvar += delta) <= 0) 2730 tp->t_rttvar = 1 << 2; 2731 } else { 2732 /* 2733 * No rtt measurement yet - use the unsmoothed rtt. 2734 * Set the variance to half the rtt (so our first 2735 * retransmit happens at 3*rtt). 2736 */ 2737 tp->t_srtt = rtt << (TCP_RTT_SHIFT + 2); 2738 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT + 2 - 1); 2739 } 2740 tp->t_rtttime = 0; 2741 tp->t_rxtshift = 0; 2742 2743 /* 2744 * the retransmit should happen at rtt + 4 * rttvar. 2745 * Because of the way we do the smoothing, srtt and rttvar 2746 * will each average +1/2 tick of bias. When we compute 2747 * the retransmit timer, we want 1/2 tick of rounding and 2748 * 1 extra tick because of +-1/2 tick uncertainty in the 2749 * firing of the timer. The bias will give us exactly the 2750 * 1.5 tick we need. But, because the bias is 2751 * statistical, we have to test that we don't drop below 2752 * the minimum feasible timer (which is 2 ticks). 2753 */ 2754 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), 2755 max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX); 2756 2757 /* 2758 * We received an ack for a packet that wasn't retransmitted; 2759 * it is probably safe to discard any error indications we've 2760 * received recently. This isn't quite right, but close enough 2761 * for now (a route might have failed after we sent a segment, 2762 * and the return path might not be symmetrical). 2763 */ 2764 tp->t_softerror = 0; 2765 } 2766 2767 /* 2768 * Checks for partial ack. If partial ack arrives, force the retransmission 2769 * of the next unacknowledged segment, do not clear tp->t_dupacks, and return 2770 * 1. By setting snd_nxt to th_ack, this forces retransmission timer to 2771 * be started again. If the ack advances at least to tp->snd_recover, return 0. 2772 */ 2773 int 2774 tcp_newreno(tp, th) 2775 struct tcpcb *tp; 2776 struct tcphdr *th; 2777 { 2778 tcp_seq onxt = tp->snd_nxt; 2779 u_long ocwnd = tp->snd_cwnd; 2780 2781 if (SEQ_LT(th->th_ack, tp->snd_recover)) { 2782 /* 2783 * snd_una has not yet been updated and the socket's send 2784 * buffer has not yet drained off the ACK'd data, so we 2785 * have to leave snd_una as it was to get the correct data 2786 * offset in tcp_output(). 2787 */ 2788 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2789 tp->t_rtttime = 0; 2790 tp->snd_nxt = th->th_ack; 2791 /* 2792 * Set snd_cwnd to one segment beyond ACK'd offset. snd_una 2793 * is not yet updated when we're called. 2794 */ 2795 tp->snd_cwnd = tp->t_segsz + (th->th_ack - tp->snd_una); 2796 (void) tcp_output(tp); 2797 tp->snd_cwnd = ocwnd; 2798 if (SEQ_GT(onxt, tp->snd_nxt)) 2799 tp->snd_nxt = onxt; 2800 /* 2801 * Partial window deflation. Relies on fact that tp->snd_una 2802 * not updated yet. 2803 */ 2804 tp->snd_cwnd -= (th->th_ack - tp->snd_una - tp->t_segsz); 2805 return 1; 2806 } 2807 return 0; 2808 } 2809 2810 2811 /* 2812 * TCP compressed state engine. Currently used to hold compressed 2813 * state for SYN_RECEIVED. 2814 */ 2815 2816 u_long syn_cache_count; 2817 u_int32_t syn_hash1, syn_hash2; 2818 2819 #define SYN_HASH(sa, sp, dp) \ 2820 ((((sa)->s_addr^syn_hash1)*(((((u_int32_t)(dp))<<16) + \ 2821 ((u_int32_t)(sp)))^syn_hash2))) 2822 #ifndef INET6 2823 #define SYN_HASHALL(hash, src, dst) \ 2824 do { \ 2825 hash = SYN_HASH(&((struct sockaddr_in *)(src))->sin_addr, \ 2826 ((struct sockaddr_in *)(src))->sin_port, \ 2827 ((struct sockaddr_in *)(dst))->sin_port); \ 2828 } while (0) 2829 #else 2830 #define SYN_HASH6(sa, sp, dp) \ 2831 ((((sa)->s6_addr32[0] ^ (sa)->s6_addr32[3] ^ syn_hash1) * \ 2832 (((((u_int32_t)(dp))<<16) + ((u_int32_t)(sp)))^syn_hash2)) \ 2833 & 0x7fffffff) 2834 2835 #define SYN_HASHALL(hash, src, dst) \ 2836 do { \ 2837 switch ((src)->sa_family) { \ 2838 case AF_INET: \ 2839 hash = SYN_HASH(&((struct sockaddr_in *)(src))->sin_addr, \ 2840 ((struct sockaddr_in *)(src))->sin_port, \ 2841 ((struct sockaddr_in *)(dst))->sin_port); \ 2842 break; \ 2843 case AF_INET6: \ 2844 hash = SYN_HASH6(&((struct sockaddr_in6 *)(src))->sin6_addr, \ 2845 ((struct sockaddr_in6 *)(src))->sin6_port, \ 2846 ((struct sockaddr_in6 *)(dst))->sin6_port); \ 2847 break; \ 2848 default: \ 2849 hash = 0; \ 2850 } \ 2851 } while (/*CONSTCOND*/0) 2852 #endif /* INET6 */ 2853 2854 #define SYN_CACHE_RM(sc) \ 2855 do { \ 2856 TAILQ_REMOVE(&tcp_syn_cache[(sc)->sc_bucketidx].sch_bucket, \ 2857 (sc), sc_bucketq); \ 2858 (sc)->sc_tp = NULL; \ 2859 LIST_REMOVE((sc), sc_tpq); \ 2860 tcp_syn_cache[(sc)->sc_bucketidx].sch_length--; \ 2861 callout_stop(&(sc)->sc_timer); \ 2862 syn_cache_count--; \ 2863 } while (/*CONSTCOND*/0) 2864 2865 #define SYN_CACHE_PUT(sc) \ 2866 do { \ 2867 if ((sc)->sc_ipopts) \ 2868 (void) m_free((sc)->sc_ipopts); \ 2869 if ((sc)->sc_route4.ro_rt != NULL) \ 2870 RTFREE((sc)->sc_route4.ro_rt); \ 2871 pool_put(&syn_cache_pool, (sc)); \ 2872 } while (/*CONSTCOND*/0) 2873 2874 struct pool syn_cache_pool; 2875 2876 /* 2877 * We don't estimate RTT with SYNs, so each packet starts with the default 2878 * RTT and each timer step has a fixed timeout value. 2879 */ 2880 #define SYN_CACHE_TIMER_ARM(sc) \ 2881 do { \ 2882 TCPT_RANGESET((sc)->sc_rxtcur, \ 2883 TCPTV_SRTTDFLT * tcp_backoff[(sc)->sc_rxtshift], TCPTV_MIN, \ 2884 TCPTV_REXMTMAX); \ 2885 callout_reset(&(sc)->sc_timer, \ 2886 (sc)->sc_rxtcur * (hz / PR_SLOWHZ), syn_cache_timer, (sc)); \ 2887 } while (/*CONSTCOND*/0) 2888 2889 #define SYN_CACHE_TIMESTAMP(sc) (tcp_now - (sc)->sc_timebase) 2890 2891 void 2892 syn_cache_init() 2893 { 2894 int i; 2895 2896 /* Initialize the hash buckets. */ 2897 for (i = 0; i < tcp_syn_cache_size; i++) 2898 TAILQ_INIT(&tcp_syn_cache[i].sch_bucket); 2899 2900 /* Initialize the syn cache pool. */ 2901 pool_init(&syn_cache_pool, sizeof(struct syn_cache), 0, 0, 0, 2902 "synpl", NULL); 2903 } 2904 2905 void 2906 syn_cache_insert(sc, tp) 2907 struct syn_cache *sc; 2908 struct tcpcb *tp; 2909 { 2910 struct syn_cache_head *scp; 2911 struct syn_cache *sc2; 2912 int s; 2913 2914 /* 2915 * If there are no entries in the hash table, reinitialize 2916 * the hash secrets. 2917 */ 2918 if (syn_cache_count == 0) { 2919 struct timeval tv; 2920 microtime(&tv); 2921 syn_hash1 = arc4random() ^ (u_long)≻ 2922 syn_hash2 = arc4random() ^ tv.tv_usec; 2923 } 2924 2925 SYN_HASHALL(sc->sc_hash, &sc->sc_src.sa, &sc->sc_dst.sa); 2926 sc->sc_bucketidx = sc->sc_hash % tcp_syn_cache_size; 2927 scp = &tcp_syn_cache[sc->sc_bucketidx]; 2928 2929 /* 2930 * Make sure that we don't overflow the per-bucket 2931 * limit or the total cache size limit. 2932 */ 2933 s = splsoftnet(); 2934 if (scp->sch_length >= tcp_syn_bucket_limit) { 2935 tcpstat.tcps_sc_bucketoverflow++; 2936 /* 2937 * The bucket is full. Toss the oldest element in the 2938 * bucket. This will be the first entry in the bucket. 2939 */ 2940 sc2 = TAILQ_FIRST(&scp->sch_bucket); 2941 #ifdef DIAGNOSTIC 2942 /* 2943 * This should never happen; we should always find an 2944 * entry in our bucket. 2945 */ 2946 if (sc2 == NULL) 2947 panic("syn_cache_insert: bucketoverflow: impossible"); 2948 #endif 2949 SYN_CACHE_RM(sc2); 2950 SYN_CACHE_PUT(sc2); 2951 } else if (syn_cache_count >= tcp_syn_cache_limit) { 2952 struct syn_cache_head *scp2, *sce; 2953 2954 tcpstat.tcps_sc_overflowed++; 2955 /* 2956 * The cache is full. Toss the oldest entry in the 2957 * first non-empty bucket we can find. 2958 * 2959 * XXX We would really like to toss the oldest 2960 * entry in the cache, but we hope that this 2961 * condition doesn't happen very often. 2962 */ 2963 scp2 = scp; 2964 if (TAILQ_EMPTY(&scp2->sch_bucket)) { 2965 sce = &tcp_syn_cache[tcp_syn_cache_size]; 2966 for (++scp2; scp2 != scp; scp2++) { 2967 if (scp2 >= sce) 2968 scp2 = &tcp_syn_cache[0]; 2969 if (! TAILQ_EMPTY(&scp2->sch_bucket)) 2970 break; 2971 } 2972 #ifdef DIAGNOSTIC 2973 /* 2974 * This should never happen; we should always find a 2975 * non-empty bucket. 2976 */ 2977 if (scp2 == scp) 2978 panic("syn_cache_insert: cacheoverflow: " 2979 "impossible"); 2980 #endif 2981 } 2982 sc2 = TAILQ_FIRST(&scp2->sch_bucket); 2983 SYN_CACHE_RM(sc2); 2984 SYN_CACHE_PUT(sc2); 2985 } 2986 2987 /* 2988 * Initialize the entry's timer. 2989 */ 2990 sc->sc_rxttot = 0; 2991 sc->sc_rxtshift = 0; 2992 SYN_CACHE_TIMER_ARM(sc); 2993 2994 /* Link it from tcpcb entry */ 2995 LIST_INSERT_HEAD(&tp->t_sc, sc, sc_tpq); 2996 2997 /* Put it into the bucket. */ 2998 TAILQ_INSERT_TAIL(&scp->sch_bucket, sc, sc_bucketq); 2999 scp->sch_length++; 3000 syn_cache_count++; 3001 3002 tcpstat.tcps_sc_added++; 3003 splx(s); 3004 } 3005 3006 /* 3007 * Walk the timer queues, looking for SYN,ACKs that need to be retransmitted. 3008 * If we have retransmitted an entry the maximum number of times, expire 3009 * that entry. 3010 */ 3011 void 3012 syn_cache_timer(void *arg) 3013 { 3014 struct syn_cache *sc = arg; 3015 int s; 3016 3017 s = splsoftnet(); 3018 3019 if (__predict_false(sc->sc_rxtshift == TCP_MAXRXTSHIFT)) { 3020 /* Drop it -- too many retransmissions. */ 3021 goto dropit; 3022 } 3023 3024 /* 3025 * Compute the total amount of time this entry has 3026 * been on a queue. If this entry has been on longer 3027 * than the keep alive timer would allow, expire it. 3028 */ 3029 sc->sc_rxttot += sc->sc_rxtcur; 3030 if (sc->sc_rxttot >= TCPTV_KEEP_INIT) 3031 goto dropit; 3032 3033 tcpstat.tcps_sc_retransmitted++; 3034 (void) syn_cache_respond(sc, NULL); 3035 3036 /* Advance the timer back-off. */ 3037 sc->sc_rxtshift++; 3038 SYN_CACHE_TIMER_ARM(sc); 3039 3040 splx(s); 3041 return; 3042 3043 dropit: 3044 tcpstat.tcps_sc_timed_out++; 3045 SYN_CACHE_RM(sc); 3046 SYN_CACHE_PUT(sc); 3047 splx(s); 3048 } 3049 3050 /* 3051 * Remove syn cache created by the specified tcb entry, 3052 * because this does not make sense to keep them 3053 * (if there's no tcb entry, syn cache entry will never be used) 3054 */ 3055 void 3056 syn_cache_cleanup(tp) 3057 struct tcpcb *tp; 3058 { 3059 struct syn_cache *sc, *nsc; 3060 int s; 3061 3062 s = splsoftnet(); 3063 3064 for (sc = LIST_FIRST(&tp->t_sc); sc != NULL; sc = nsc) { 3065 nsc = LIST_NEXT(sc, sc_tpq); 3066 3067 #ifdef DIAGNOSTIC 3068 if (sc->sc_tp != tp) 3069 panic("invalid sc_tp in syn_cache_cleanup"); 3070 #endif 3071 SYN_CACHE_RM(sc); 3072 SYN_CACHE_PUT(sc); 3073 } 3074 /* just for safety */ 3075 LIST_INIT(&tp->t_sc); 3076 3077 splx(s); 3078 } 3079 3080 /* 3081 * Find an entry in the syn cache. 3082 */ 3083 struct syn_cache * 3084 syn_cache_lookup(src, dst, headp) 3085 struct sockaddr *src; 3086 struct sockaddr *dst; 3087 struct syn_cache_head **headp; 3088 { 3089 struct syn_cache *sc; 3090 struct syn_cache_head *scp; 3091 u_int32_t hash; 3092 int s; 3093 3094 SYN_HASHALL(hash, src, dst); 3095 3096 scp = &tcp_syn_cache[hash % tcp_syn_cache_size]; 3097 *headp = scp; 3098 s = splsoftnet(); 3099 for (sc = TAILQ_FIRST(&scp->sch_bucket); sc != NULL; 3100 sc = TAILQ_NEXT(sc, sc_bucketq)) { 3101 if (sc->sc_hash != hash) 3102 continue; 3103 if (!bcmp(&sc->sc_src, src, src->sa_len) && 3104 !bcmp(&sc->sc_dst, dst, dst->sa_len)) { 3105 splx(s); 3106 return (sc); 3107 } 3108 } 3109 splx(s); 3110 return (NULL); 3111 } 3112 3113 /* 3114 * This function gets called when we receive an ACK for a 3115 * socket in the LISTEN state. We look up the connection 3116 * in the syn cache, and if its there, we pull it out of 3117 * the cache and turn it into a full-blown connection in 3118 * the SYN-RECEIVED state. 3119 * 3120 * The return values may not be immediately obvious, and their effects 3121 * can be subtle, so here they are: 3122 * 3123 * NULL SYN was not found in cache; caller should drop the 3124 * packet and send an RST. 3125 * 3126 * -1 We were unable to create the new connection, and are 3127 * aborting it. An ACK,RST is being sent to the peer 3128 * (unless we got screwey sequence numbners; see below), 3129 * because the 3-way handshake has been completed. Caller 3130 * should not free the mbuf, since we may be using it. If 3131 * we are not, we will free it. 3132 * 3133 * Otherwise, the return value is a pointer to the new socket 3134 * associated with the connection. 3135 */ 3136 struct socket * 3137 syn_cache_get(src, dst, th, hlen, tlen, so, m) 3138 struct sockaddr *src; 3139 struct sockaddr *dst; 3140 struct tcphdr *th; 3141 unsigned int hlen, tlen; 3142 struct socket *so; 3143 struct mbuf *m; 3144 { 3145 struct syn_cache *sc; 3146 struct syn_cache_head *scp; 3147 struct inpcb *inp = NULL; 3148 #ifdef INET6 3149 struct in6pcb *in6p = NULL; 3150 #endif 3151 struct tcpcb *tp = 0; 3152 struct mbuf *am; 3153 int s; 3154 struct socket *oso; 3155 3156 s = splsoftnet(); 3157 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 3158 splx(s); 3159 return (NULL); 3160 } 3161 3162 /* 3163 * Verify the sequence and ack numbers. Try getting the correct 3164 * response again. 3165 */ 3166 if ((th->th_ack != sc->sc_iss + 1) || 3167 SEQ_LEQ(th->th_seq, sc->sc_irs) || 3168 SEQ_GT(th->th_seq, sc->sc_irs + 1 + sc->sc_win)) { 3169 (void) syn_cache_respond(sc, m); 3170 splx(s); 3171 return ((struct socket *)(-1)); 3172 } 3173 3174 /* Remove this cache entry */ 3175 SYN_CACHE_RM(sc); 3176 splx(s); 3177 3178 /* 3179 * Ok, create the full blown connection, and set things up 3180 * as they would have been set up if we had created the 3181 * connection when the SYN arrived. If we can't create 3182 * the connection, abort it. 3183 */ 3184 /* 3185 * inp still has the OLD in_pcb stuff, set the 3186 * v6-related flags on the new guy, too. This is 3187 * done particularly for the case where an AF_INET6 3188 * socket is bound only to a port, and a v4 connection 3189 * comes in on that port. 3190 * we also copy the flowinfo from the original pcb 3191 * to the new one. 3192 */ 3193 { 3194 struct inpcb *parentinpcb; 3195 3196 parentinpcb = (struct inpcb *)so->so_pcb; 3197 3198 oso = so; 3199 so = sonewconn(so, SS_ISCONNECTED); 3200 if (so == NULL) 3201 goto resetandabort; 3202 3203 switch (so->so_proto->pr_domain->dom_family) { 3204 #ifdef INET 3205 case AF_INET: 3206 inp = sotoinpcb(so); 3207 break; 3208 #endif 3209 #ifdef INET6 3210 case AF_INET6: 3211 in6p = sotoin6pcb(so); 3212 break; 3213 #endif 3214 } 3215 } 3216 switch (src->sa_family) { 3217 #ifdef INET 3218 case AF_INET: 3219 if (inp) { 3220 inp->inp_laddr = ((struct sockaddr_in *)dst)->sin_addr; 3221 inp->inp_lport = ((struct sockaddr_in *)dst)->sin_port; 3222 inp->inp_options = ip_srcroute(); 3223 in_pcbstate(inp, INP_BOUND); 3224 if (inp->inp_options == NULL) { 3225 inp->inp_options = sc->sc_ipopts; 3226 sc->sc_ipopts = NULL; 3227 } 3228 } 3229 #ifdef INET6 3230 else if (in6p) { 3231 /* IPv4 packet to AF_INET6 socket */ 3232 bzero(&in6p->in6p_laddr, sizeof(in6p->in6p_laddr)); 3233 in6p->in6p_laddr.s6_addr16[5] = htons(0xffff); 3234 bcopy(&((struct sockaddr_in *)dst)->sin_addr, 3235 &in6p->in6p_laddr.s6_addr32[3], 3236 sizeof(((struct sockaddr_in *)dst)->sin_addr)); 3237 in6p->in6p_lport = ((struct sockaddr_in *)dst)->sin_port; 3238 in6totcpcb(in6p)->t_family = AF_INET; 3239 } 3240 #endif 3241 break; 3242 #endif 3243 #ifdef INET6 3244 case AF_INET6: 3245 if (in6p) { 3246 in6p->in6p_laddr = ((struct sockaddr_in6 *)dst)->sin6_addr; 3247 in6p->in6p_lport = ((struct sockaddr_in6 *)dst)->sin6_port; 3248 #if 0 3249 in6p->in6p_flowinfo = ip6->ip6_flow & IPV6_FLOWINFO_MASK; 3250 /*inp->inp_options = ip6_srcroute();*/ /* soon. */ 3251 #endif 3252 } 3253 break; 3254 #endif 3255 } 3256 #ifdef INET6 3257 if (in6p && in6totcpcb(in6p)->t_family == AF_INET6 && sotoinpcb(oso)) { 3258 struct in6pcb *oin6p = sotoin6pcb(oso); 3259 /* inherit socket options from the listening socket */ 3260 in6p->in6p_flags |= (oin6p->in6p_flags & IN6P_CONTROLOPTS); 3261 if (in6p->in6p_flags & IN6P_CONTROLOPTS) { 3262 m_freem(in6p->in6p_options); 3263 in6p->in6p_options = 0; 3264 } 3265 ip6_savecontrol(in6p, &in6p->in6p_options, 3266 mtod(m, struct ip6_hdr *), m); 3267 } 3268 #endif 3269 3270 #ifdef IPSEC 3271 /* 3272 * we make a copy of policy, instead of sharing the policy, 3273 * for better behavior in terms of SA lookup and dead SA removal. 3274 */ 3275 if (inp) { 3276 /* copy old policy into new socket's */ 3277 if (ipsec_copy_pcbpolicy(sotoinpcb(oso)->inp_sp, inp->inp_sp)) 3278 printf("tcp_input: could not copy policy\n"); 3279 } 3280 #ifdef INET6 3281 else if (in6p) { 3282 /* copy old policy into new socket's */ 3283 if (ipsec_copy_pcbpolicy(sotoin6pcb(oso)->in6p_sp, 3284 in6p->in6p_sp)) 3285 printf("tcp_input: could not copy policy\n"); 3286 } 3287 #endif 3288 #endif 3289 3290 /* 3291 * Give the new socket our cached route reference. 3292 */ 3293 if (inp) 3294 inp->inp_route = sc->sc_route4; /* struct assignment */ 3295 #ifdef INET6 3296 else 3297 in6p->in6p_route = sc->sc_route6; 3298 #endif 3299 sc->sc_route4.ro_rt = NULL; 3300 3301 am = m_get(M_DONTWAIT, MT_SONAME); /* XXX */ 3302 if (am == NULL) 3303 goto resetandabort; 3304 am->m_len = src->sa_len; 3305 bcopy(src, mtod(am, caddr_t), src->sa_len); 3306 if (inp) { 3307 if (in_pcbconnect(inp, am)) { 3308 (void) m_free(am); 3309 goto resetandabort; 3310 } 3311 } 3312 #ifdef INET6 3313 else if (in6p) { 3314 if (src->sa_family == AF_INET) { 3315 /* IPv4 packet to AF_INET6 socket */ 3316 struct sockaddr_in6 *sin6; 3317 sin6 = mtod(am, struct sockaddr_in6 *); 3318 am->m_len = sizeof(*sin6); 3319 bzero(sin6, sizeof(*sin6)); 3320 sin6->sin6_family = AF_INET6; 3321 sin6->sin6_len = sizeof(*sin6); 3322 sin6->sin6_port = ((struct sockaddr_in *)src)->sin_port; 3323 sin6->sin6_addr.s6_addr16[5] = htons(0xffff); 3324 bcopy(&((struct sockaddr_in *)src)->sin_addr, 3325 &sin6->sin6_addr.s6_addr32[3], 3326 sizeof(sin6->sin6_addr.s6_addr32[3])); 3327 } 3328 if (in6_pcbconnect(in6p, am)) { 3329 (void) m_free(am); 3330 goto resetandabort; 3331 } 3332 } 3333 #endif 3334 else { 3335 (void) m_free(am); 3336 goto resetandabort; 3337 } 3338 (void) m_free(am); 3339 3340 if (inp) 3341 tp = intotcpcb(inp); 3342 #ifdef INET6 3343 else if (in6p) 3344 tp = in6totcpcb(in6p); 3345 #endif 3346 else 3347 tp = NULL; 3348 tp->t_flags = sototcpcb(oso)->t_flags & TF_NODELAY; 3349 if (sc->sc_request_r_scale != 15) { 3350 tp->requested_s_scale = sc->sc_requested_s_scale; 3351 tp->request_r_scale = sc->sc_request_r_scale; 3352 tp->snd_scale = sc->sc_requested_s_scale; 3353 tp->rcv_scale = sc->sc_request_r_scale; 3354 tp->t_flags |= TF_RCVD_SCALE; 3355 } 3356 if (sc->sc_flags & SCF_TIMESTAMP) 3357 tp->t_flags |= TF_RCVD_TSTMP; 3358 tp->ts_timebase = sc->sc_timebase; 3359 3360 tp->t_template = tcp_template(tp); 3361 if (tp->t_template == 0) { 3362 tp = tcp_drop(tp, ENOBUFS); /* destroys socket */ 3363 so = NULL; 3364 m_freem(m); 3365 goto abort; 3366 } 3367 3368 tp->iss = sc->sc_iss; 3369 tp->irs = sc->sc_irs; 3370 tcp_sendseqinit(tp); 3371 tcp_rcvseqinit(tp); 3372 tp->t_state = TCPS_SYN_RECEIVED; 3373 TCP_TIMER_ARM(tp, TCPT_KEEP, TCPTV_KEEP_INIT); 3374 tcpstat.tcps_accepts++; 3375 3376 /* Initialize tp->t_ourmss before we deal with the peer's! */ 3377 tp->t_ourmss = sc->sc_ourmaxseg; 3378 tcp_mss_from_peer(tp, sc->sc_peermaxseg); 3379 3380 /* 3381 * Initialize the initial congestion window. If we 3382 * had to retransmit the SYN,ACK, we must initialize cwnd 3383 * to 1 segment (i.e. the Loss Window). 3384 */ 3385 if (sc->sc_rxtshift) 3386 tp->snd_cwnd = tp->t_peermss; 3387 else 3388 tp->snd_cwnd = TCP_INITIAL_WINDOW(tcp_init_win, tp->t_peermss); 3389 3390 tcp_rmx_rtt(tp); 3391 tp->snd_wl1 = sc->sc_irs; 3392 tp->rcv_up = sc->sc_irs + 1; 3393 3394 /* 3395 * This is what whould have happened in tcp_ouput() when 3396 * the SYN,ACK was sent. 3397 */ 3398 tp->snd_up = tp->snd_una; 3399 tp->snd_max = tp->snd_nxt = tp->iss+1; 3400 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 3401 if (sc->sc_win > 0 && SEQ_GT(tp->rcv_nxt + sc->sc_win, tp->rcv_adv)) 3402 tp->rcv_adv = tp->rcv_nxt + sc->sc_win; 3403 tp->last_ack_sent = tp->rcv_nxt; 3404 3405 tcpstat.tcps_sc_completed++; 3406 SYN_CACHE_PUT(sc); 3407 return (so); 3408 3409 resetandabort: 3410 (void) tcp_respond(NULL, m, m, th, 3411 th->th_seq + tlen, (tcp_seq)0, TH_RST|TH_ACK); 3412 abort: 3413 if (so != NULL) 3414 (void) soabort(so); 3415 SYN_CACHE_PUT(sc); 3416 tcpstat.tcps_sc_aborted++; 3417 return ((struct socket *)(-1)); 3418 } 3419 3420 /* 3421 * This function is called when we get a RST for a 3422 * non-existent connection, so that we can see if the 3423 * connection is in the syn cache. If it is, zap it. 3424 */ 3425 3426 void 3427 syn_cache_reset(src, dst, th) 3428 struct sockaddr *src; 3429 struct sockaddr *dst; 3430 struct tcphdr *th; 3431 { 3432 struct syn_cache *sc; 3433 struct syn_cache_head *scp; 3434 int s = splsoftnet(); 3435 3436 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 3437 splx(s); 3438 return; 3439 } 3440 if (SEQ_LT(th->th_seq, sc->sc_irs) || 3441 SEQ_GT(th->th_seq, sc->sc_irs+1)) { 3442 splx(s); 3443 return; 3444 } 3445 SYN_CACHE_RM(sc); 3446 splx(s); 3447 tcpstat.tcps_sc_reset++; 3448 SYN_CACHE_PUT(sc); 3449 } 3450 3451 void 3452 syn_cache_unreach(src, dst, th) 3453 struct sockaddr *src; 3454 struct sockaddr *dst; 3455 struct tcphdr *th; 3456 { 3457 struct syn_cache *sc; 3458 struct syn_cache_head *scp; 3459 int s; 3460 3461 s = splsoftnet(); 3462 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 3463 splx(s); 3464 return; 3465 } 3466 /* If the sequence number != sc_iss, then it's a bogus ICMP msg */ 3467 if (ntohl (th->th_seq) != sc->sc_iss) { 3468 splx(s); 3469 return; 3470 } 3471 3472 /* 3473 * If we've rertransmitted 3 times and this is our second error, 3474 * we remove the entry. Otherwise, we allow it to continue on. 3475 * This prevents us from incorrectly nuking an entry during a 3476 * spurious network outage. 3477 * 3478 * See tcp_notify(). 3479 */ 3480 if ((sc->sc_flags & SCF_UNREACH) == 0 || sc->sc_rxtshift < 3) { 3481 sc->sc_flags |= SCF_UNREACH; 3482 splx(s); 3483 return; 3484 } 3485 3486 SYN_CACHE_RM(sc); 3487 splx(s); 3488 tcpstat.tcps_sc_unreach++; 3489 SYN_CACHE_PUT(sc); 3490 } 3491 3492 /* 3493 * Given a LISTEN socket and an inbound SYN request, add 3494 * this to the syn cache, and send back a segment: 3495 * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK> 3496 * to the source. 3497 * 3498 * IMPORTANT NOTE: We do _NOT_ ACK data that might accompany the SYN. 3499 * Doing so would require that we hold onto the data and deliver it 3500 * to the application. However, if we are the target of a SYN-flood 3501 * DoS attack, an attacker could send data which would eventually 3502 * consume all available buffer space if it were ACKed. By not ACKing 3503 * the data, we avoid this DoS scenario. 3504 */ 3505 3506 int 3507 syn_cache_add(src, dst, th, hlen, so, m, optp, optlen, oi) 3508 struct sockaddr *src; 3509 struct sockaddr *dst; 3510 struct tcphdr *th; 3511 unsigned int hlen; 3512 struct socket *so; 3513 struct mbuf *m; 3514 u_char *optp; 3515 int optlen; 3516 struct tcp_opt_info *oi; 3517 { 3518 struct tcpcb tb, *tp; 3519 long win; 3520 struct syn_cache *sc; 3521 struct syn_cache_head *scp; 3522 struct mbuf *ipopts; 3523 3524 tp = sototcpcb(so); 3525 3526 /* 3527 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN 3528 * 3529 * Note this check is performed in tcp_input() very early on. 3530 */ 3531 3532 /* 3533 * Initialize some local state. 3534 */ 3535 win = sbspace(&so->so_rcv); 3536 if (win > TCP_MAXWIN) 3537 win = TCP_MAXWIN; 3538 3539 switch (src->sa_family) { 3540 #ifdef INET 3541 case AF_INET: 3542 /* 3543 * Remember the IP options, if any. 3544 */ 3545 ipopts = ip_srcroute(); 3546 break; 3547 #endif 3548 default: 3549 ipopts = NULL; 3550 } 3551 3552 if (optp) { 3553 tb.t_flags = tcp_do_rfc1323 ? (TF_REQ_SCALE|TF_REQ_TSTMP) : 0; 3554 tcp_dooptions(&tb, optp, optlen, th, oi); 3555 } else 3556 tb.t_flags = 0; 3557 3558 /* 3559 * See if we already have an entry for this connection. 3560 * If we do, resend the SYN,ACK. We do not count this 3561 * as a retransmission (XXX though maybe we should). 3562 */ 3563 if ((sc = syn_cache_lookup(src, dst, &scp)) != NULL) { 3564 tcpstat.tcps_sc_dupesyn++; 3565 if (ipopts) { 3566 /* 3567 * If we were remembering a previous source route, 3568 * forget it and use the new one we've been given. 3569 */ 3570 if (sc->sc_ipopts) 3571 (void) m_free(sc->sc_ipopts); 3572 sc->sc_ipopts = ipopts; 3573 } 3574 sc->sc_timestamp = tb.ts_recent; 3575 if (syn_cache_respond(sc, m) == 0) { 3576 tcpstat.tcps_sndacks++; 3577 tcpstat.tcps_sndtotal++; 3578 } 3579 return (1); 3580 } 3581 3582 sc = pool_get(&syn_cache_pool, PR_NOWAIT); 3583 if (sc == NULL) { 3584 if (ipopts) 3585 (void) m_free(ipopts); 3586 return (0); 3587 } 3588 3589 /* 3590 * Fill in the cache, and put the necessary IP and TCP 3591 * options into the reply. 3592 */ 3593 callout_init(&sc->sc_timer); 3594 bzero(sc, sizeof(struct syn_cache)); 3595 bcopy(src, &sc->sc_src, src->sa_len); 3596 bcopy(dst, &sc->sc_dst, dst->sa_len); 3597 sc->sc_flags = 0; 3598 sc->sc_ipopts = ipopts; 3599 sc->sc_irs = th->th_seq; 3600 switch (src->sa_family) { 3601 #ifdef INET 3602 case AF_INET: 3603 { 3604 struct sockaddr_in *srcin = (void *) src; 3605 struct sockaddr_in *dstin = (void *) dst; 3606 3607 sc->sc_iss = tcp_new_iss1(&dstin->sin_addr, 3608 &srcin->sin_addr, dstin->sin_port, 3609 srcin->sin_port, sizeof(dstin->sin_addr), 0); 3610 break; 3611 } 3612 #endif /* INET */ 3613 #ifdef INET6 3614 case AF_INET6: 3615 { 3616 struct sockaddr_in6 *srcin6 = (void *) src; 3617 struct sockaddr_in6 *dstin6 = (void *) dst; 3618 3619 sc->sc_iss = tcp_new_iss1(&dstin6->sin6_addr, 3620 &srcin6->sin6_addr, dstin6->sin6_port, 3621 srcin6->sin6_port, sizeof(dstin6->sin6_addr), 0); 3622 break; 3623 } 3624 #endif /* INET6 */ 3625 } 3626 sc->sc_peermaxseg = oi->maxseg; 3627 sc->sc_ourmaxseg = tcp_mss_to_advertise(m->m_flags & M_PKTHDR ? 3628 m->m_pkthdr.rcvif : NULL, 3629 sc->sc_src.sa.sa_family); 3630 sc->sc_win = win; 3631 sc->sc_timebase = tcp_now; /* see tcp_newtcpcb() */ 3632 sc->sc_timestamp = tb.ts_recent; 3633 if (tcp_do_rfc1323 && (tb.t_flags & TF_RCVD_TSTMP)) 3634 sc->sc_flags |= SCF_TIMESTAMP; 3635 if ((tb.t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 3636 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 3637 sc->sc_requested_s_scale = tb.requested_s_scale; 3638 sc->sc_request_r_scale = 0; 3639 while (sc->sc_request_r_scale < TCP_MAX_WINSHIFT && 3640 TCP_MAXWIN << sc->sc_request_r_scale < 3641 so->so_rcv.sb_hiwat) 3642 sc->sc_request_r_scale++; 3643 } else { 3644 sc->sc_requested_s_scale = 15; 3645 sc->sc_request_r_scale = 15; 3646 } 3647 sc->sc_tp = tp; 3648 if (syn_cache_respond(sc, m) == 0) { 3649 syn_cache_insert(sc, tp); 3650 tcpstat.tcps_sndacks++; 3651 tcpstat.tcps_sndtotal++; 3652 } else { 3653 SYN_CACHE_PUT(sc); 3654 tcpstat.tcps_sc_dropped++; 3655 } 3656 return (1); 3657 } 3658 3659 int 3660 syn_cache_respond(sc, m) 3661 struct syn_cache *sc; 3662 struct mbuf *m; 3663 { 3664 struct route *ro; 3665 u_int8_t *optp; 3666 int optlen, error; 3667 u_int16_t tlen; 3668 struct ip *ip = NULL; 3669 #ifdef INET6 3670 struct ip6_hdr *ip6 = NULL; 3671 #endif 3672 struct tcphdr *th; 3673 u_int hlen; 3674 3675 switch (sc->sc_src.sa.sa_family) { 3676 case AF_INET: 3677 hlen = sizeof(struct ip); 3678 ro = &sc->sc_route4; 3679 break; 3680 #ifdef INET6 3681 case AF_INET6: 3682 hlen = sizeof(struct ip6_hdr); 3683 ro = (struct route *)&sc->sc_route6; 3684 break; 3685 #endif 3686 default: 3687 if (m) 3688 m_freem(m); 3689 return EAFNOSUPPORT; 3690 } 3691 3692 /* Compute the size of the TCP options. */ 3693 optlen = 4 + (sc->sc_request_r_scale != 15 ? 4 : 0) + 3694 ((sc->sc_flags & SCF_TIMESTAMP) ? TCPOLEN_TSTAMP_APPA : 0); 3695 3696 tlen = hlen + sizeof(struct tcphdr) + optlen; 3697 3698 /* 3699 * Create the IP+TCP header from scratch. 3700 */ 3701 if (m) 3702 m_freem(m); 3703 #ifdef DIAGNOSTIC 3704 if (max_linkhdr + tlen > MCLBYTES) 3705 return (ENOBUFS); 3706 #endif 3707 MGETHDR(m, M_DONTWAIT, MT_DATA); 3708 if (m && tlen > MHLEN) { 3709 MCLGET(m, M_DONTWAIT); 3710 if ((m->m_flags & M_EXT) == 0) { 3711 m_freem(m); 3712 m = NULL; 3713 } 3714 } 3715 if (m == NULL) 3716 return (ENOBUFS); 3717 3718 /* Fixup the mbuf. */ 3719 m->m_data += max_linkhdr; 3720 m->m_len = m->m_pkthdr.len = tlen; 3721 #ifdef IPSEC 3722 if (sc->sc_tp) { 3723 struct tcpcb *tp; 3724 struct socket *so; 3725 3726 tp = sc->sc_tp; 3727 if (tp->t_inpcb) 3728 so = tp->t_inpcb->inp_socket; 3729 #ifdef INET6 3730 else if (tp->t_in6pcb) 3731 so = tp->t_in6pcb->in6p_socket; 3732 #endif 3733 else 3734 so = NULL; 3735 /* use IPsec policy on listening socket, on SYN ACK */ 3736 if (ipsec_setsocket(m, so) != 0) { 3737 m_freem(m); 3738 return ENOBUFS; 3739 } 3740 } 3741 #endif 3742 m->m_pkthdr.rcvif = NULL; 3743 memset(mtod(m, u_char *), 0, tlen); 3744 3745 switch (sc->sc_src.sa.sa_family) { 3746 case AF_INET: 3747 ip = mtod(m, struct ip *); 3748 ip->ip_dst = sc->sc_src.sin.sin_addr; 3749 ip->ip_src = sc->sc_dst.sin.sin_addr; 3750 ip->ip_p = IPPROTO_TCP; 3751 th = (struct tcphdr *)(ip + 1); 3752 th->th_dport = sc->sc_src.sin.sin_port; 3753 th->th_sport = sc->sc_dst.sin.sin_port; 3754 break; 3755 #ifdef INET6 3756 case AF_INET6: 3757 ip6 = mtod(m, struct ip6_hdr *); 3758 ip6->ip6_dst = sc->sc_src.sin6.sin6_addr; 3759 ip6->ip6_src = sc->sc_dst.sin6.sin6_addr; 3760 ip6->ip6_nxt = IPPROTO_TCP; 3761 /* ip6_plen will be updated in ip6_output() */ 3762 th = (struct tcphdr *)(ip6 + 1); 3763 th->th_dport = sc->sc_src.sin6.sin6_port; 3764 th->th_sport = sc->sc_dst.sin6.sin6_port; 3765 break; 3766 #endif 3767 default: 3768 th = NULL; 3769 } 3770 3771 th->th_seq = htonl(sc->sc_iss); 3772 th->th_ack = htonl(sc->sc_irs + 1); 3773 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 3774 th->th_flags = TH_SYN|TH_ACK; 3775 th->th_win = htons(sc->sc_win); 3776 /* th_sum already 0 */ 3777 /* th_urp already 0 */ 3778 3779 /* Tack on the TCP options. */ 3780 optp = (u_int8_t *)(th + 1); 3781 *optp++ = TCPOPT_MAXSEG; 3782 *optp++ = 4; 3783 *optp++ = (sc->sc_ourmaxseg >> 8) & 0xff; 3784 *optp++ = sc->sc_ourmaxseg & 0xff; 3785 3786 if (sc->sc_request_r_scale != 15) { 3787 *((u_int32_t *)optp) = htonl(TCPOPT_NOP << 24 | 3788 TCPOPT_WINDOW << 16 | TCPOLEN_WINDOW << 8 | 3789 sc->sc_request_r_scale); 3790 optp += 4; 3791 } 3792 3793 if (sc->sc_flags & SCF_TIMESTAMP) { 3794 u_int32_t *lp = (u_int32_t *)(optp); 3795 /* Form timestamp option as shown in appendix A of RFC 1323. */ 3796 *lp++ = htonl(TCPOPT_TSTAMP_HDR); 3797 *lp++ = htonl(SYN_CACHE_TIMESTAMP(sc)); 3798 *lp = htonl(sc->sc_timestamp); 3799 optp += TCPOLEN_TSTAMP_APPA; 3800 } 3801 3802 /* Compute the packet's checksum. */ 3803 switch (sc->sc_src.sa.sa_family) { 3804 case AF_INET: 3805 ip->ip_len = htons(tlen - hlen); 3806 th->th_sum = 0; 3807 th->th_sum = in_cksum(m, tlen); 3808 break; 3809 #ifdef INET6 3810 case AF_INET6: 3811 ip6->ip6_plen = htons(tlen - hlen); 3812 th->th_sum = 0; 3813 th->th_sum = in6_cksum(m, IPPROTO_TCP, hlen, tlen - hlen); 3814 break; 3815 #endif 3816 } 3817 3818 /* 3819 * Fill in some straggling IP bits. Note the stack expects 3820 * ip_len to be in host order, for convenience. 3821 */ 3822 switch (sc->sc_src.sa.sa_family) { 3823 #ifdef INET 3824 case AF_INET: 3825 ip->ip_len = htons(tlen); 3826 ip->ip_ttl = ip_defttl; 3827 /* XXX tos? */ 3828 break; 3829 #endif 3830 #ifdef INET6 3831 case AF_INET6: 3832 ip6->ip6_vfc &= ~IPV6_VERSION_MASK; 3833 ip6->ip6_vfc |= IPV6_VERSION; 3834 ip6->ip6_plen = htons(tlen - hlen); 3835 /* ip6_hlim will be initialized afterwards */ 3836 /* XXX flowlabel? */ 3837 break; 3838 #endif 3839 } 3840 3841 switch (sc->sc_src.sa.sa_family) { 3842 #ifdef INET 3843 case AF_INET: 3844 error = ip_output(m, sc->sc_ipopts, ro, 3845 (ip_mtudisc ? IP_MTUDISC : 0), 3846 NULL); 3847 break; 3848 #endif 3849 #ifdef INET6 3850 case AF_INET6: 3851 ip6->ip6_hlim = in6_selecthlim(NULL, 3852 ro->ro_rt ? ro->ro_rt->rt_ifp : NULL); 3853 3854 error = ip6_output(m, NULL /*XXX*/, (struct route_in6 *)ro, 3855 0, NULL, NULL); 3856 break; 3857 #endif 3858 default: 3859 error = EAFNOSUPPORT; 3860 break; 3861 } 3862 return (error); 3863 } 3864