1 /* $NetBSD: tcp_input.c,v 1.173 2003/07/20 16:35:07 he 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 1.173 2003/07/20 16:35:07 he 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/in_var.h> 184 #include <netinet/ip_var.h> 185 186 #ifdef INET6 187 #ifndef INET 188 #include <netinet/in.h> 189 #endif 190 #include <netinet/ip6.h> 191 #include <netinet6/ip6_var.h> 192 #include <netinet6/in6_pcb.h> 193 #include <netinet6/ip6_var.h> 194 #include <netinet6/in6_var.h> 195 #include <netinet/icmp6.h> 196 #include <netinet6/nd6.h> 197 #endif 198 199 #ifndef INET6 200 /* always need ip6.h for IP6_EXTHDR_GET */ 201 #include <netinet/ip6.h> 202 #endif 203 204 #include <netinet/tcp.h> 205 #include <netinet/tcp_fsm.h> 206 #include <netinet/tcp_seq.h> 207 #include <netinet/tcp_timer.h> 208 #include <netinet/tcp_var.h> 209 #include <netinet/tcpip.h> 210 #include <netinet/tcp_debug.h> 211 212 #include <machine/stdarg.h> 213 214 #ifdef IPSEC 215 #include <netinet6/ipsec.h> 216 #include <netkey/key.h> 217 #endif /*IPSEC*/ 218 #ifdef INET6 219 #include "faith.h" 220 #if defined(NFAITH) && NFAITH > 0 221 #include <net/if_faith.h> 222 #endif 223 #endif 224 225 int tcprexmtthresh = 3; 226 int tcp_log_refused; 227 228 static int tcp_rst_ppslim_count = 0; 229 static struct timeval tcp_rst_ppslim_last; 230 231 #define TCP_PAWS_IDLE (24 * 24 * 60 * 60 * PR_SLOWHZ) 232 233 /* for modulo comparisons of timestamps */ 234 #define TSTMP_LT(a,b) ((int)((a)-(b)) < 0) 235 #define TSTMP_GEQ(a,b) ((int)((a)-(b)) >= 0) 236 237 /* 238 * Neighbor Discovery, Neighbor Unreachability Detection Upper layer hint. 239 */ 240 #ifdef INET6 241 #define ND6_HINT(tp) \ 242 do { \ 243 if (tp && tp->t_in6pcb && tp->t_family == AF_INET6 \ 244 && tp->t_in6pcb->in6p_route.ro_rt) { \ 245 nd6_nud_hint(tp->t_in6pcb->in6p_route.ro_rt, NULL, 0); \ 246 } \ 247 } while (/*CONSTCOND*/ 0) 248 #else 249 #define ND6_HINT(tp) 250 #endif 251 252 /* 253 * Macro to compute ACK transmission behavior. Delay the ACK unless 254 * we have already delayed an ACK (must send an ACK every two segments). 255 * We also ACK immediately if we received a PUSH and the ACK-on-PUSH 256 * option is enabled. 257 */ 258 #define TCP_SETUP_ACK(tp, th) \ 259 do { \ 260 if ((tp)->t_flags & TF_DELACK || \ 261 (tcp_ack_on_push && (th)->th_flags & TH_PUSH)) \ 262 tp->t_flags |= TF_ACKNOW; \ 263 else \ 264 TCP_SET_DELACK(tp); \ 265 } while (/*CONSTCOND*/ 0) 266 267 /* 268 * Convert TCP protocol fields to host order for easier processing. 269 */ 270 #define TCP_FIELDS_TO_HOST(th) \ 271 do { \ 272 NTOHL((th)->th_seq); \ 273 NTOHL((th)->th_ack); \ 274 NTOHS((th)->th_win); \ 275 NTOHS((th)->th_urp); \ 276 } while (/*CONSTCOND*/ 0) 277 278 /* 279 * ... and reverse the above. 280 */ 281 #define TCP_FIELDS_TO_NET(th) \ 282 do { \ 283 HTONL((th)->th_seq); \ 284 HTONL((th)->th_ack); \ 285 HTONS((th)->th_win); \ 286 HTONS((th)->th_urp); \ 287 } while (/*CONSTCOND*/ 0) 288 289 #ifdef TCP_CSUM_COUNTERS 290 #include <sys/device.h> 291 292 extern struct evcnt tcp_hwcsum_ok; 293 extern struct evcnt tcp_hwcsum_bad; 294 extern struct evcnt tcp_hwcsum_data; 295 extern struct evcnt tcp_swcsum; 296 297 #define TCP_CSUM_COUNTER_INCR(ev) (ev)->ev_count++ 298 299 #else 300 301 #define TCP_CSUM_COUNTER_INCR(ev) /* nothing */ 302 303 #endif /* TCP_CSUM_COUNTERS */ 304 305 #ifdef TCP_REASS_COUNTERS 306 #include <sys/device.h> 307 308 extern struct evcnt tcp_reass_; 309 extern struct evcnt tcp_reass_empty; 310 extern struct evcnt tcp_reass_iteration[8]; 311 extern struct evcnt tcp_reass_prependfirst; 312 extern struct evcnt tcp_reass_prepend; 313 extern struct evcnt tcp_reass_insert; 314 extern struct evcnt tcp_reass_inserttail; 315 extern struct evcnt tcp_reass_append; 316 extern struct evcnt tcp_reass_appendtail; 317 extern struct evcnt tcp_reass_overlaptail; 318 extern struct evcnt tcp_reass_overlapfront; 319 extern struct evcnt tcp_reass_segdup; 320 extern struct evcnt tcp_reass_fragdup; 321 322 #define TCP_REASS_COUNTER_INCR(ev) (ev)->ev_count++ 323 324 #else 325 326 #define TCP_REASS_COUNTER_INCR(ev) /* nothing */ 327 328 #endif /* TCP_REASS_COUNTERS */ 329 330 #ifdef INET 331 static void tcp4_log_refused __P((const struct ip *, const struct tcphdr *)); 332 #endif 333 #ifdef INET6 334 static void tcp6_log_refused 335 __P((const struct ip6_hdr *, const struct tcphdr *)); 336 #endif 337 338 int 339 tcp_reass(tp, th, m, tlen) 340 struct tcpcb *tp; 341 struct tcphdr *th; 342 struct mbuf *m; 343 int *tlen; 344 { 345 struct ipqent *p, *q, *nq, *tiqe = NULL; 346 struct socket *so = NULL; 347 int pkt_flags; 348 tcp_seq pkt_seq; 349 unsigned pkt_len; 350 u_long rcvpartdupbyte = 0; 351 u_long rcvoobyte; 352 #ifdef TCP_REASS_COUNTERS 353 u_int count = 0; 354 #endif 355 356 if (tp->t_inpcb) 357 so = tp->t_inpcb->inp_socket; 358 #ifdef INET6 359 else if (tp->t_in6pcb) 360 so = tp->t_in6pcb->in6p_socket; 361 #endif 362 363 TCP_REASS_LOCK_CHECK(tp); 364 365 /* 366 * Call with th==0 after become established to 367 * force pre-ESTABLISHED data up to user socket. 368 */ 369 if (th == 0) 370 goto present; 371 372 rcvoobyte = *tlen; 373 /* 374 * Copy these to local variables because the tcpiphdr 375 * gets munged while we are collapsing mbufs. 376 */ 377 pkt_seq = th->th_seq; 378 pkt_len = *tlen; 379 pkt_flags = th->th_flags; 380 381 TCP_REASS_COUNTER_INCR(&tcp_reass_); 382 383 if ((p = TAILQ_LAST(&tp->segq, ipqehead)) != NULL) { 384 /* 385 * When we miss a packet, the vast majority of time we get 386 * packets that follow it in order. So optimize for that. 387 */ 388 if (pkt_seq == p->ipqe_seq + p->ipqe_len) { 389 p->ipqe_len += pkt_len; 390 p->ipqe_flags |= pkt_flags; 391 m_cat(p->ipqe_m, m); 392 tiqe = p; 393 TAILQ_REMOVE(&tp->timeq, p, ipqe_timeq); 394 TCP_REASS_COUNTER_INCR(&tcp_reass_appendtail); 395 goto skip_replacement; 396 } 397 /* 398 * While we're here, if the pkt is completely beyond 399 * anything we have, just insert it at the tail. 400 */ 401 if (SEQ_GT(pkt_seq, p->ipqe_seq + p->ipqe_len)) { 402 TCP_REASS_COUNTER_INCR(&tcp_reass_inserttail); 403 goto insert_it; 404 } 405 } 406 407 q = TAILQ_FIRST(&tp->segq); 408 409 if (q != NULL) { 410 /* 411 * If this segment immediately precedes the first out-of-order 412 * block, simply slap the segment in front of it and (mostly) 413 * skip the complicated logic. 414 */ 415 if (pkt_seq + pkt_len == q->ipqe_seq) { 416 q->ipqe_seq = pkt_seq; 417 q->ipqe_len += pkt_len; 418 q->ipqe_flags |= pkt_flags; 419 m_cat(m, q->ipqe_m); 420 q->ipqe_m = m; 421 tiqe = q; 422 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 423 TCP_REASS_COUNTER_INCR(&tcp_reass_prependfirst); 424 goto skip_replacement; 425 } 426 } else { 427 TCP_REASS_COUNTER_INCR(&tcp_reass_empty); 428 } 429 430 /* 431 * Find a segment which begins after this one does. 432 */ 433 for (p = NULL; q != NULL; q = nq) { 434 nq = TAILQ_NEXT(q, ipqe_q); 435 #ifdef TCP_REASS_COUNTERS 436 count++; 437 #endif 438 /* 439 * If the received segment is just right after this 440 * fragment, merge the two together and then check 441 * for further overlaps. 442 */ 443 if (q->ipqe_seq + q->ipqe_len == pkt_seq) { 444 #ifdef TCPREASS_DEBUG 445 printf("tcp_reass[%p]: concat %u:%u(%u) to %u:%u(%u)\n", 446 tp, pkt_seq, pkt_seq + pkt_len, pkt_len, 447 q->ipqe_seq, q->ipqe_seq + q->ipqe_len, q->ipqe_len); 448 #endif 449 pkt_len += q->ipqe_len; 450 pkt_flags |= q->ipqe_flags; 451 pkt_seq = q->ipqe_seq; 452 m_cat(q->ipqe_m, m); 453 m = q->ipqe_m; 454 TCP_REASS_COUNTER_INCR(&tcp_reass_append); 455 goto free_ipqe; 456 } 457 /* 458 * If the received segment is completely past this 459 * fragment, we need to go the next fragment. 460 */ 461 if (SEQ_LT(q->ipqe_seq + q->ipqe_len, pkt_seq)) { 462 p = q; 463 continue; 464 } 465 /* 466 * If the fragment is past the received segment, 467 * it (or any following) can't be concatenated. 468 */ 469 if (SEQ_GT(q->ipqe_seq, pkt_seq + pkt_len)) { 470 TCP_REASS_COUNTER_INCR(&tcp_reass_insert); 471 break; 472 } 473 474 /* 475 * We've received all the data in this segment before. 476 * mark it as a duplicate and return. 477 */ 478 if (SEQ_LEQ(q->ipqe_seq, pkt_seq) && 479 SEQ_GEQ(q->ipqe_seq + q->ipqe_len, pkt_seq + pkt_len)) { 480 tcpstat.tcps_rcvduppack++; 481 tcpstat.tcps_rcvdupbyte += pkt_len; 482 m_freem(m); 483 if (tiqe != NULL) 484 pool_put(&ipqent_pool, tiqe); 485 TCP_REASS_COUNTER_INCR(&tcp_reass_segdup); 486 return (0); 487 } 488 /* 489 * Received segment completely overlaps this fragment 490 * so we drop the fragment (this keeps the temporal 491 * ordering of segments correct). 492 */ 493 if (SEQ_GEQ(q->ipqe_seq, pkt_seq) && 494 SEQ_LEQ(q->ipqe_seq + q->ipqe_len, pkt_seq + pkt_len)) { 495 rcvpartdupbyte += q->ipqe_len; 496 m_freem(q->ipqe_m); 497 TCP_REASS_COUNTER_INCR(&tcp_reass_fragdup); 498 goto free_ipqe; 499 } 500 /* 501 * RX'ed segment extends past the end of the 502 * fragment. Drop the overlapping bytes. Then 503 * merge the fragment and segment then treat as 504 * a longer received packet. 505 */ 506 if (SEQ_LT(q->ipqe_seq, pkt_seq) 507 && SEQ_GT(q->ipqe_seq + q->ipqe_len, pkt_seq)) { 508 int overlap = q->ipqe_seq + q->ipqe_len - pkt_seq; 509 #ifdef TCPREASS_DEBUG 510 printf("tcp_reass[%p]: trim starting %d bytes of %u:%u(%u)\n", 511 tp, overlap, 512 pkt_seq, pkt_seq + pkt_len, pkt_len); 513 #endif 514 m_adj(m, overlap); 515 rcvpartdupbyte += overlap; 516 m_cat(q->ipqe_m, m); 517 m = q->ipqe_m; 518 pkt_seq = q->ipqe_seq; 519 pkt_len += q->ipqe_len - overlap; 520 rcvoobyte -= overlap; 521 TCP_REASS_COUNTER_INCR(&tcp_reass_overlaptail); 522 goto free_ipqe; 523 } 524 /* 525 * RX'ed segment extends past the front of the 526 * fragment. Drop the overlapping bytes on the 527 * received packet. The packet will then be 528 * contatentated with this fragment a bit later. 529 */ 530 if (SEQ_GT(q->ipqe_seq, pkt_seq) 531 && SEQ_LT(q->ipqe_seq, pkt_seq + pkt_len)) { 532 int overlap = pkt_seq + pkt_len - q->ipqe_seq; 533 #ifdef TCPREASS_DEBUG 534 printf("tcp_reass[%p]: trim trailing %d bytes of %u:%u(%u)\n", 535 tp, overlap, 536 pkt_seq, pkt_seq + pkt_len, pkt_len); 537 #endif 538 m_adj(m, -overlap); 539 pkt_len -= overlap; 540 rcvpartdupbyte += overlap; 541 TCP_REASS_COUNTER_INCR(&tcp_reass_overlapfront); 542 rcvoobyte -= overlap; 543 } 544 /* 545 * If the received segment immediates precedes this 546 * fragment then tack the fragment onto this segment 547 * and reinsert the data. 548 */ 549 if (q->ipqe_seq == pkt_seq + pkt_len) { 550 #ifdef TCPREASS_DEBUG 551 printf("tcp_reass[%p]: append %u:%u(%u) to %u:%u(%u)\n", 552 tp, q->ipqe_seq, q->ipqe_seq + q->ipqe_len, q->ipqe_len, 553 pkt_seq, pkt_seq + pkt_len, pkt_len); 554 #endif 555 pkt_len += q->ipqe_len; 556 pkt_flags |= q->ipqe_flags; 557 m_cat(m, q->ipqe_m); 558 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 559 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 560 if (tiqe == NULL) { 561 tiqe = q; 562 } else { 563 pool_put(&ipqent_pool, q); 564 } 565 TCP_REASS_COUNTER_INCR(&tcp_reass_prepend); 566 break; 567 } 568 /* 569 * If the fragment is before the segment, remember it. 570 * When this loop is terminated, p will contain the 571 * pointer to fragment that is right before the received 572 * segment. 573 */ 574 if (SEQ_LEQ(q->ipqe_seq, pkt_seq)) 575 p = q; 576 577 continue; 578 579 /* 580 * This is a common operation. It also will allow 581 * to save doing a malloc/free in most instances. 582 */ 583 free_ipqe: 584 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 585 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 586 if (tiqe == NULL) { 587 tiqe = q; 588 } else { 589 pool_put(&ipqent_pool, q); 590 } 591 } 592 593 #ifdef TCP_REASS_COUNTERS 594 if (count > 7) 595 TCP_REASS_COUNTER_INCR(&tcp_reass_iteration[0]); 596 else if (count > 0) 597 TCP_REASS_COUNTER_INCR(&tcp_reass_iteration[count]); 598 #endif 599 600 insert_it: 601 602 /* 603 * Allocate a new queue entry since the received segment did not 604 * collapse onto any other out-of-order block; thus we are allocating 605 * a new block. If it had collapsed, tiqe would not be NULL and 606 * we would be reusing it. 607 * XXX If we can't, just drop the packet. XXX 608 */ 609 if (tiqe == NULL) { 610 tiqe = pool_get(&ipqent_pool, PR_NOWAIT); 611 if (tiqe == NULL) { 612 tcpstat.tcps_rcvmemdrop++; 613 m_freem(m); 614 return (0); 615 } 616 } 617 618 /* 619 * Update the counters. 620 */ 621 tcpstat.tcps_rcvoopack++; 622 tcpstat.tcps_rcvoobyte += rcvoobyte; 623 if (rcvpartdupbyte) { 624 tcpstat.tcps_rcvpartduppack++; 625 tcpstat.tcps_rcvpartdupbyte += rcvpartdupbyte; 626 } 627 628 /* 629 * Insert the new fragment queue entry into both queues. 630 */ 631 tiqe->ipqe_m = m; 632 tiqe->ipqe_seq = pkt_seq; 633 tiqe->ipqe_len = pkt_len; 634 tiqe->ipqe_flags = pkt_flags; 635 if (p == NULL) { 636 TAILQ_INSERT_HEAD(&tp->segq, tiqe, ipqe_q); 637 #ifdef TCPREASS_DEBUG 638 if (tiqe->ipqe_seq != tp->rcv_nxt) 639 printf("tcp_reass[%p]: insert %u:%u(%u) at front\n", 640 tp, pkt_seq, pkt_seq + pkt_len, pkt_len); 641 #endif 642 } else { 643 TAILQ_INSERT_AFTER(&tp->segq, p, tiqe, ipqe_q); 644 #ifdef TCPREASS_DEBUG 645 printf("tcp_reass[%p]: insert %u:%u(%u) after %u:%u(%u)\n", 646 tp, pkt_seq, pkt_seq + pkt_len, pkt_len, 647 p->ipqe_seq, p->ipqe_seq + p->ipqe_len, p->ipqe_len); 648 #endif 649 } 650 651 skip_replacement: 652 653 TAILQ_INSERT_HEAD(&tp->timeq, tiqe, ipqe_timeq); 654 655 present: 656 /* 657 * Present data to user, advancing rcv_nxt through 658 * completed sequence space. 659 */ 660 if (TCPS_HAVEESTABLISHED(tp->t_state) == 0) 661 return (0); 662 q = TAILQ_FIRST(&tp->segq); 663 if (q == NULL || q->ipqe_seq != tp->rcv_nxt) 664 return (0); 665 if (tp->t_state == TCPS_SYN_RECEIVED && q->ipqe_len) 666 return (0); 667 668 tp->rcv_nxt += q->ipqe_len; 669 pkt_flags = q->ipqe_flags & TH_FIN; 670 ND6_HINT(tp); 671 672 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 673 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 674 if (so->so_state & SS_CANTRCVMORE) 675 m_freem(q->ipqe_m); 676 else 677 sbappendstream(&so->so_rcv, q->ipqe_m); 678 pool_put(&ipqent_pool, q); 679 sorwakeup(so); 680 return (pkt_flags); 681 } 682 683 #ifdef INET6 684 int 685 tcp6_input(mp, offp, proto) 686 struct mbuf **mp; 687 int *offp, proto; 688 { 689 struct mbuf *m = *mp; 690 691 /* 692 * draft-itojun-ipv6-tcp-to-anycast 693 * better place to put this in? 694 */ 695 if (m->m_flags & M_ANYCAST6) { 696 struct ip6_hdr *ip6; 697 if (m->m_len < sizeof(struct ip6_hdr)) { 698 if ((m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) { 699 tcpstat.tcps_rcvshort++; 700 return IPPROTO_DONE; 701 } 702 } 703 ip6 = mtod(m, struct ip6_hdr *); 704 icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR, 705 (caddr_t)&ip6->ip6_dst - (caddr_t)ip6); 706 return IPPROTO_DONE; 707 } 708 709 tcp_input(m, *offp, proto); 710 return IPPROTO_DONE; 711 } 712 #endif 713 714 #ifdef INET 715 static void 716 tcp4_log_refused(ip, th) 717 const struct ip *ip; 718 const struct tcphdr *th; 719 { 720 char src[4*sizeof "123"]; 721 char dst[4*sizeof "123"]; 722 723 if (ip) { 724 strlcpy(src, inet_ntoa(ip->ip_src), sizeof(src)); 725 strlcpy(dst, inet_ntoa(ip->ip_dst), sizeof(dst)); 726 } 727 else { 728 strlcpy(src, "(unknown)", sizeof(src)); 729 strlcpy(dst, "(unknown)", sizeof(dst)); 730 } 731 log(LOG_INFO, 732 "Connection attempt to TCP %s:%d from %s:%d\n", 733 dst, ntohs(th->th_dport), 734 src, ntohs(th->th_sport)); 735 } 736 #endif 737 738 #ifdef INET6 739 static void 740 tcp6_log_refused(ip6, th) 741 const struct ip6_hdr *ip6; 742 const struct tcphdr *th; 743 { 744 char src[INET6_ADDRSTRLEN]; 745 char dst[INET6_ADDRSTRLEN]; 746 747 if (ip6) { 748 strlcpy(src, ip6_sprintf(&ip6->ip6_src), sizeof(src)); 749 strlcpy(dst, ip6_sprintf(&ip6->ip6_dst), sizeof(dst)); 750 } 751 else { 752 strlcpy(src, "(unknown v6)", sizeof(src)); 753 strlcpy(dst, "(unknown v6)", sizeof(dst)); 754 } 755 log(LOG_INFO, 756 "Connection attempt to TCP [%s]:%d from [%s]:%d\n", 757 dst, ntohs(th->th_dport), 758 src, ntohs(th->th_sport)); 759 } 760 #endif 761 762 /* 763 * TCP input routine, follows pages 65-76 of the 764 * protocol specification dated September, 1981 very closely. 765 */ 766 void 767 #if __STDC__ 768 tcp_input(struct mbuf *m, ...) 769 #else 770 tcp_input(m, va_alist) 771 struct mbuf *m; 772 #endif 773 { 774 struct tcphdr *th; 775 struct ip *ip; 776 struct inpcb *inp; 777 #ifdef INET6 778 struct ip6_hdr *ip6; 779 struct in6pcb *in6p; 780 #endif 781 u_int8_t *optp = NULL; 782 int optlen = 0; 783 int len, tlen, toff, hdroptlen = 0; 784 struct tcpcb *tp = 0; 785 int tiflags; 786 struct socket *so = NULL; 787 int todrop, acked, ourfinisacked, needoutput = 0; 788 #ifdef TCP_DEBUG 789 short ostate = 0; 790 #endif 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 MCLAIM(m, &tcp_rx_mowner); 800 va_start(ap, m); 801 toff = va_arg(ap, int); 802 (void)va_arg(ap, int); /* ignore value, advance ap */ 803 va_end(ap); 804 805 tcpstat.tcps_rcvtotal++; 806 807 bzero(&opti, sizeof(opti)); 808 opti.ts_present = 0; 809 opti.maxseg = 0; 810 811 /* 812 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN. 813 * 814 * TCP is, by definition, unicast, so we reject all 815 * multicast outright. 816 * 817 * Note, there are additional src/dst address checks in 818 * the AF-specific code below. 819 */ 820 if (m->m_flags & (M_BCAST|M_MCAST)) { 821 /* XXX stat */ 822 goto drop; 823 } 824 #ifdef INET6 825 if (m->m_flags & M_ANYCAST6) { 826 /* XXX stat */ 827 goto drop; 828 } 829 #endif 830 831 /* 832 * Get IP and TCP header together in first mbuf. 833 * Note: IP leaves IP header in first mbuf. 834 */ 835 ip = mtod(m, struct ip *); 836 #ifdef INET6 837 ip6 = NULL; 838 #endif 839 switch (ip->ip_v) { 840 #ifdef INET 841 case 4: 842 af = AF_INET; 843 iphlen = sizeof(struct ip); 844 ip = mtod(m, struct ip *); 845 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, 846 sizeof(struct tcphdr)); 847 if (th == NULL) { 848 tcpstat.tcps_rcvshort++; 849 return; 850 } 851 /* We do the checksum after PCB lookup... */ 852 len = ntohs(ip->ip_len); 853 tlen = len - toff; 854 break; 855 #endif 856 #ifdef INET6 857 case 6: 858 ip = NULL; 859 iphlen = sizeof(struct ip6_hdr); 860 af = AF_INET6; 861 ip6 = mtod(m, struct ip6_hdr *); 862 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, 863 sizeof(struct tcphdr)); 864 if (th == NULL) { 865 tcpstat.tcps_rcvshort++; 866 return; 867 } 868 869 /* Be proactive about malicious use of IPv4 mapped address */ 870 if (IN6_IS_ADDR_V4MAPPED(&ip6->ip6_src) || 871 IN6_IS_ADDR_V4MAPPED(&ip6->ip6_dst)) { 872 /* XXX stat */ 873 goto drop; 874 } 875 876 /* 877 * Be proactive about unspecified IPv6 address in source. 878 * As we use all-zero to indicate unbounded/unconnected pcb, 879 * unspecified IPv6 address can be used to confuse us. 880 * 881 * Note that packets with unspecified IPv6 destination is 882 * already dropped in ip6_input. 883 */ 884 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 885 /* XXX stat */ 886 goto drop; 887 } 888 889 /* 890 * Make sure destination address is not multicast. 891 * Source address checked in ip6_input(). 892 */ 893 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) { 894 /* XXX stat */ 895 goto drop; 896 } 897 898 /* We do the checksum after PCB lookup... */ 899 len = m->m_pkthdr.len; 900 tlen = len - toff; 901 break; 902 #endif 903 default: 904 m_freem(m); 905 return; 906 } 907 908 KASSERT(TCP_HDR_ALIGNED_P(th)); 909 910 /* 911 * Check that TCP offset makes sense, 912 * pull out TCP options and adjust length. XXX 913 */ 914 off = th->th_off << 2; 915 if (off < sizeof (struct tcphdr) || off > tlen) { 916 tcpstat.tcps_rcvbadoff++; 917 goto drop; 918 } 919 tlen -= off; 920 921 /* 922 * tcp_input() has been modified to use tlen to mean the TCP data 923 * length throughout the function. Other functions can use 924 * m->m_pkthdr.len as the basis for calculating the TCP data length. 925 * rja 926 */ 927 928 if (off > sizeof (struct tcphdr)) { 929 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, off); 930 if (th == NULL) { 931 tcpstat.tcps_rcvshort++; 932 return; 933 } 934 /* 935 * NOTE: ip/ip6 will not be affected by m_pulldown() 936 * (as they're before toff) and we don't need to update those. 937 */ 938 KASSERT(TCP_HDR_ALIGNED_P(th)); 939 optlen = off - sizeof (struct tcphdr); 940 optp = ((u_int8_t *)th) + sizeof(struct tcphdr); 941 /* 942 * Do quick retrieval of timestamp options ("options 943 * prediction?"). If timestamp is the only option and it's 944 * formatted as recommended in RFC 1323 appendix A, we 945 * quickly get the values now and not bother calling 946 * tcp_dooptions(), etc. 947 */ 948 if ((optlen == TCPOLEN_TSTAMP_APPA || 949 (optlen > TCPOLEN_TSTAMP_APPA && 950 optp[TCPOLEN_TSTAMP_APPA] == TCPOPT_EOL)) && 951 *(u_int32_t *)optp == htonl(TCPOPT_TSTAMP_HDR) && 952 (th->th_flags & TH_SYN) == 0) { 953 opti.ts_present = 1; 954 opti.ts_val = ntohl(*(u_int32_t *)(optp + 4)); 955 opti.ts_ecr = ntohl(*(u_int32_t *)(optp + 8)); 956 optp = NULL; /* we've parsed the options */ 957 } 958 } 959 tiflags = th->th_flags; 960 961 /* 962 * Locate pcb for segment. 963 */ 964 findpcb: 965 inp = NULL; 966 #ifdef INET6 967 in6p = NULL; 968 #endif 969 switch (af) { 970 #ifdef INET 971 case AF_INET: 972 inp = in_pcblookup_connect(&tcbtable, ip->ip_src, th->th_sport, 973 ip->ip_dst, th->th_dport); 974 if (inp == 0) { 975 ++tcpstat.tcps_pcbhashmiss; 976 inp = in_pcblookup_bind(&tcbtable, ip->ip_dst, th->th_dport); 977 } 978 #ifdef INET6 979 if (inp == 0) { 980 struct in6_addr s, d; 981 982 /* mapped addr case */ 983 bzero(&s, sizeof(s)); 984 s.s6_addr16[5] = htons(0xffff); 985 bcopy(&ip->ip_src, &s.s6_addr32[3], sizeof(ip->ip_src)); 986 bzero(&d, sizeof(d)); 987 d.s6_addr16[5] = htons(0xffff); 988 bcopy(&ip->ip_dst, &d.s6_addr32[3], sizeof(ip->ip_dst)); 989 in6p = in6_pcblookup_connect(&tcb6, &s, th->th_sport, 990 &d, th->th_dport, 0); 991 if (in6p == 0) { 992 ++tcpstat.tcps_pcbhashmiss; 993 in6p = in6_pcblookup_bind(&tcb6, &d, 994 th->th_dport, 0); 995 } 996 } 997 #endif 998 #ifndef INET6 999 if (inp == 0) 1000 #else 1001 if (inp == 0 && in6p == 0) 1002 #endif 1003 { 1004 ++tcpstat.tcps_noport; 1005 if (tcp_log_refused && 1006 (tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) { 1007 tcp4_log_refused(ip, th); 1008 } 1009 TCP_FIELDS_TO_HOST(th); 1010 goto dropwithreset_ratelim; 1011 } 1012 #ifdef IPSEC 1013 if (inp && ipsec4_in_reject(m, inp)) { 1014 ipsecstat.in_polvio++; 1015 goto drop; 1016 } 1017 #ifdef INET6 1018 else if (in6p && ipsec4_in_reject_so(m, in6p->in6p_socket)) { 1019 ipsecstat.in_polvio++; 1020 goto drop; 1021 } 1022 #endif 1023 #endif /*IPSEC*/ 1024 break; 1025 #endif /*INET*/ 1026 #ifdef INET6 1027 case AF_INET6: 1028 { 1029 int faith; 1030 1031 #if defined(NFAITH) && NFAITH > 0 1032 faith = faithprefix(&ip6->ip6_dst); 1033 #else 1034 faith = 0; 1035 #endif 1036 in6p = in6_pcblookup_connect(&tcb6, &ip6->ip6_src, th->th_sport, 1037 &ip6->ip6_dst, th->th_dport, faith); 1038 if (in6p == NULL) { 1039 ++tcpstat.tcps_pcbhashmiss; 1040 in6p = in6_pcblookup_bind(&tcb6, &ip6->ip6_dst, 1041 th->th_dport, faith); 1042 } 1043 if (in6p == NULL) { 1044 ++tcpstat.tcps_noport; 1045 if (tcp_log_refused && 1046 (tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) { 1047 tcp6_log_refused(ip6, th); 1048 } 1049 TCP_FIELDS_TO_HOST(th); 1050 goto dropwithreset_ratelim; 1051 } 1052 #ifdef IPSEC 1053 if (ipsec6_in_reject(m, in6p)) { 1054 ipsec6stat.in_polvio++; 1055 goto drop; 1056 } 1057 #endif /*IPSEC*/ 1058 break; 1059 } 1060 #endif 1061 } 1062 1063 /* 1064 * If the state is CLOSED (i.e., TCB does not exist) then 1065 * all data in the incoming segment is discarded. 1066 * If the TCB exists but is in CLOSED state, it is embryonic, 1067 * but should either do a listen or a connect soon. 1068 */ 1069 tp = NULL; 1070 so = NULL; 1071 if (inp) { 1072 tp = intotcpcb(inp); 1073 so = inp->inp_socket; 1074 } 1075 #ifdef INET6 1076 else if (in6p) { 1077 tp = in6totcpcb(in6p); 1078 so = in6p->in6p_socket; 1079 } 1080 #endif 1081 if (tp == 0) { 1082 TCP_FIELDS_TO_HOST(th); 1083 goto dropwithreset_ratelim; 1084 } 1085 if (tp->t_state == TCPS_CLOSED) 1086 goto drop; 1087 1088 /* 1089 * Checksum extended TCP header and data. 1090 */ 1091 switch (af) { 1092 #ifdef INET 1093 case AF_INET: 1094 switch (m->m_pkthdr.csum_flags & 1095 ((m->m_pkthdr.rcvif->if_csum_flags_rx & M_CSUM_TCPv4) | 1096 M_CSUM_TCP_UDP_BAD | M_CSUM_DATA)) { 1097 case M_CSUM_TCPv4|M_CSUM_TCP_UDP_BAD: 1098 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_bad); 1099 goto badcsum; 1100 1101 case M_CSUM_TCPv4|M_CSUM_DATA: 1102 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_data); 1103 if ((m->m_pkthdr.csum_data ^ 0xffff) != 0) 1104 goto badcsum; 1105 break; 1106 1107 case M_CSUM_TCPv4: 1108 /* Checksum was okay. */ 1109 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_ok); 1110 break; 1111 1112 default: 1113 /* Must compute it ourselves. */ 1114 TCP_CSUM_COUNTER_INCR(&tcp_swcsum); 1115 if (in4_cksum(m, IPPROTO_TCP, toff, tlen + off) != 0) 1116 goto badcsum; 1117 break; 1118 } 1119 break; 1120 #endif /* INET4 */ 1121 1122 #ifdef INET6 1123 case AF_INET6: 1124 if (in6_cksum(m, IPPROTO_TCP, toff, tlen + off) != 0) 1125 goto badcsum; 1126 break; 1127 #endif /* INET6 */ 1128 } 1129 1130 TCP_FIELDS_TO_HOST(th); 1131 1132 /* Unscale the window into a 32-bit value. */ 1133 if ((tiflags & TH_SYN) == 0) 1134 tiwin = th->th_win << tp->snd_scale; 1135 else 1136 tiwin = th->th_win; 1137 1138 #ifdef INET6 1139 /* save packet options if user wanted */ 1140 if (in6p && (in6p->in6p_flags & IN6P_CONTROLOPTS)) { 1141 if (in6p->in6p_options) { 1142 m_freem(in6p->in6p_options); 1143 in6p->in6p_options = 0; 1144 } 1145 ip6_savecontrol(in6p, &in6p->in6p_options, ip6, m); 1146 } 1147 #endif 1148 1149 if (so->so_options & (SO_DEBUG|SO_ACCEPTCONN)) { 1150 union syn_cache_sa src; 1151 union syn_cache_sa dst; 1152 1153 bzero(&src, sizeof(src)); 1154 bzero(&dst, sizeof(dst)); 1155 switch (af) { 1156 #ifdef INET 1157 case AF_INET: 1158 src.sin.sin_len = sizeof(struct sockaddr_in); 1159 src.sin.sin_family = AF_INET; 1160 src.sin.sin_addr = ip->ip_src; 1161 src.sin.sin_port = th->th_sport; 1162 1163 dst.sin.sin_len = sizeof(struct sockaddr_in); 1164 dst.sin.sin_family = AF_INET; 1165 dst.sin.sin_addr = ip->ip_dst; 1166 dst.sin.sin_port = th->th_dport; 1167 break; 1168 #endif 1169 #ifdef INET6 1170 case AF_INET6: 1171 src.sin6.sin6_len = sizeof(struct sockaddr_in6); 1172 src.sin6.sin6_family = AF_INET6; 1173 src.sin6.sin6_addr = ip6->ip6_src; 1174 src.sin6.sin6_port = th->th_sport; 1175 1176 dst.sin6.sin6_len = sizeof(struct sockaddr_in6); 1177 dst.sin6.sin6_family = AF_INET6; 1178 dst.sin6.sin6_addr = ip6->ip6_dst; 1179 dst.sin6.sin6_port = th->th_dport; 1180 break; 1181 #endif /* INET6 */ 1182 default: 1183 goto badsyn; /*sanity*/ 1184 } 1185 1186 if (so->so_options & SO_DEBUG) { 1187 #ifdef TCP_DEBUG 1188 ostate = tp->t_state; 1189 #endif 1190 1191 tcp_saveti = NULL; 1192 if (iphlen + sizeof(struct tcphdr) > MHLEN) 1193 goto nosave; 1194 1195 if (m->m_len > iphlen && (m->m_flags & M_EXT) == 0) { 1196 tcp_saveti = m_copym(m, 0, iphlen, M_DONTWAIT); 1197 if (!tcp_saveti) 1198 goto nosave; 1199 } else { 1200 MGETHDR(tcp_saveti, M_DONTWAIT, MT_HEADER); 1201 if (!tcp_saveti) 1202 goto nosave; 1203 MCLAIM(m, &tcp_mowner); 1204 tcp_saveti->m_len = iphlen; 1205 m_copydata(m, 0, iphlen, 1206 mtod(tcp_saveti, caddr_t)); 1207 } 1208 1209 if (M_TRAILINGSPACE(tcp_saveti) < sizeof(struct tcphdr)) { 1210 m_freem(tcp_saveti); 1211 tcp_saveti = NULL; 1212 } else { 1213 tcp_saveti->m_len += sizeof(struct tcphdr); 1214 bcopy(th, mtod(tcp_saveti, caddr_t) + iphlen, 1215 sizeof(struct tcphdr)); 1216 } 1217 nosave:; 1218 } 1219 if (so->so_options & SO_ACCEPTCONN) { 1220 if ((tiflags & (TH_RST|TH_ACK|TH_SYN)) != TH_SYN) { 1221 if (tiflags & TH_RST) { 1222 syn_cache_reset(&src.sa, &dst.sa, th); 1223 } else if ((tiflags & (TH_ACK|TH_SYN)) == 1224 (TH_ACK|TH_SYN)) { 1225 /* 1226 * Received a SYN,ACK. This should 1227 * never happen while we are in 1228 * LISTEN. Send an RST. 1229 */ 1230 goto badsyn; 1231 } else if (tiflags & TH_ACK) { 1232 so = syn_cache_get(&src.sa, &dst.sa, 1233 th, toff, tlen, so, m); 1234 if (so == NULL) { 1235 /* 1236 * We don't have a SYN for 1237 * this ACK; send an RST. 1238 */ 1239 goto badsyn; 1240 } else if (so == 1241 (struct socket *)(-1)) { 1242 /* 1243 * We were unable to create 1244 * the connection. If the 1245 * 3-way handshake was 1246 * completed, and RST has 1247 * been sent to the peer. 1248 * Since the mbuf might be 1249 * in use for the reply, 1250 * do not free it. 1251 */ 1252 m = NULL; 1253 } else { 1254 /* 1255 * We have created a 1256 * full-blown connection. 1257 */ 1258 tp = NULL; 1259 inp = NULL; 1260 #ifdef INET6 1261 in6p = NULL; 1262 #endif 1263 switch (so->so_proto->pr_domain->dom_family) { 1264 #ifdef INET 1265 case AF_INET: 1266 inp = sotoinpcb(so); 1267 tp = intotcpcb(inp); 1268 break; 1269 #endif 1270 #ifdef INET6 1271 case AF_INET6: 1272 in6p = sotoin6pcb(so); 1273 tp = in6totcpcb(in6p); 1274 break; 1275 #endif 1276 } 1277 if (tp == NULL) 1278 goto badsyn; /*XXX*/ 1279 tiwin <<= tp->snd_scale; 1280 goto after_listen; 1281 } 1282 } else { 1283 /* 1284 * None of RST, SYN or ACK was set. 1285 * This is an invalid packet for a 1286 * TCB in LISTEN state. Send a RST. 1287 */ 1288 goto badsyn; 1289 } 1290 } else { 1291 /* 1292 * Received a SYN. 1293 */ 1294 1295 #ifdef INET6 1296 /* 1297 * If deprecated address is forbidden, we do 1298 * not accept SYN to deprecated interface 1299 * address to prevent any new inbound 1300 * connection from getting established. 1301 * When we do not accept SYN, we send a TCP 1302 * RST, with deprecated source address (instead 1303 * of dropping it). We compromise it as it is 1304 * much better for peer to send a RST, and 1305 * RST will be the final packet for the 1306 * exchange. 1307 * 1308 * If we do not forbid deprecated addresses, we 1309 * accept the SYN packet. RFC2462 does not 1310 * suggest dropping SYN in this case. 1311 * If we decipher RFC2462 5.5.4, it says like 1312 * this: 1313 * 1. use of deprecated addr with existing 1314 * communication is okay - "SHOULD continue 1315 * to be used" 1316 * 2. use of it with new communication: 1317 * (2a) "SHOULD NOT be used if alternate 1318 * address with sufficient scope is 1319 * available" 1320 * (2b) nothing mentioned otherwise. 1321 * Here we fall into (2b) case as we have no 1322 * choice in our source address selection - we 1323 * must obey the peer. 1324 * 1325 * The wording in RFC2462 is confusing, and 1326 * there are multiple description text for 1327 * deprecated address handling - worse, they 1328 * are not exactly the same. I believe 5.5.4 1329 * is the best one, so we follow 5.5.4. 1330 */ 1331 if (af == AF_INET6 && !ip6_use_deprecated) { 1332 struct in6_ifaddr *ia6; 1333 if ((ia6 = in6ifa_ifpwithaddr(m->m_pkthdr.rcvif, 1334 &ip6->ip6_dst)) && 1335 (ia6->ia6_flags & IN6_IFF_DEPRECATED)) { 1336 tp = NULL; 1337 goto dropwithreset; 1338 } 1339 } 1340 #endif 1341 1342 /* 1343 * LISTEN socket received a SYN 1344 * from itself? This can't possibly 1345 * be valid; drop the packet. 1346 */ 1347 if (th->th_sport == th->th_dport) { 1348 int i; 1349 1350 switch (af) { 1351 #ifdef INET 1352 case AF_INET: 1353 i = in_hosteq(ip->ip_src, ip->ip_dst); 1354 break; 1355 #endif 1356 #ifdef INET6 1357 case AF_INET6: 1358 i = IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &ip6->ip6_dst); 1359 break; 1360 #endif 1361 default: 1362 i = 1; 1363 } 1364 if (i) { 1365 tcpstat.tcps_badsyn++; 1366 goto drop; 1367 } 1368 } 1369 1370 /* 1371 * SYN looks ok; create compressed TCP 1372 * state for it. 1373 */ 1374 if (so->so_qlen <= so->so_qlimit && 1375 syn_cache_add(&src.sa, &dst.sa, th, tlen, 1376 so, m, optp, optlen, &opti)) 1377 m = NULL; 1378 } 1379 goto drop; 1380 } 1381 } 1382 1383 after_listen: 1384 #ifdef DIAGNOSTIC 1385 /* 1386 * Should not happen now that all embryonic connections 1387 * are handled with compressed state. 1388 */ 1389 if (tp->t_state == TCPS_LISTEN) 1390 panic("tcp_input: TCPS_LISTEN"); 1391 #endif 1392 1393 /* 1394 * Segment received on connection. 1395 * Reset idle time and keep-alive timer. 1396 */ 1397 tp->t_rcvtime = tcp_now; 1398 if (TCPS_HAVEESTABLISHED(tp->t_state)) 1399 TCP_TIMER_ARM(tp, TCPT_KEEP, tcp_keepidle); 1400 1401 /* 1402 * Process options. 1403 */ 1404 if (optp) 1405 tcp_dooptions(tp, optp, optlen, th, &opti); 1406 1407 /* 1408 * Header prediction: check for the two common cases 1409 * of a uni-directional data xfer. If the packet has 1410 * no control flags, is in-sequence, the window didn't 1411 * change and we're not retransmitting, it's a 1412 * candidate. If the length is zero and the ack moved 1413 * forward, we're the sender side of the xfer. Just 1414 * free the data acked & wake any higher level process 1415 * that was blocked waiting for space. If the length 1416 * is non-zero and the ack didn't move, we're the 1417 * receiver side. If we're getting packets in-order 1418 * (the reassembly queue is empty), add the data to 1419 * the socket buffer and note that we need a delayed ack. 1420 */ 1421 if (tp->t_state == TCPS_ESTABLISHED && 1422 (tiflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK && 1423 (!opti.ts_present || TSTMP_GEQ(opti.ts_val, tp->ts_recent)) && 1424 th->th_seq == tp->rcv_nxt && 1425 tiwin && tiwin == tp->snd_wnd && 1426 tp->snd_nxt == tp->snd_max) { 1427 1428 /* 1429 * If last ACK falls within this segment's sequence numbers, 1430 * record the timestamp. 1431 */ 1432 if (opti.ts_present && 1433 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 1434 SEQ_LT(tp->last_ack_sent, th->th_seq + tlen)) { 1435 tp->ts_recent_age = TCP_TIMESTAMP(tp); 1436 tp->ts_recent = opti.ts_val; 1437 } 1438 1439 if (tlen == 0) { 1440 if (SEQ_GT(th->th_ack, tp->snd_una) && 1441 SEQ_LEQ(th->th_ack, tp->snd_max) && 1442 tp->snd_cwnd >= tp->snd_wnd && 1443 tp->t_dupacks < tcprexmtthresh) { 1444 int slen; 1445 1446 /* 1447 * this is a pure ack for outstanding data. 1448 */ 1449 ++tcpstat.tcps_predack; 1450 if (opti.ts_present && opti.ts_ecr) 1451 tcp_xmit_timer(tp, 1452 TCP_TIMESTAMP(tp) - opti.ts_ecr + 1); 1453 else if (tp->t_rtttime && 1454 SEQ_GT(th->th_ack, tp->t_rtseq)) 1455 tcp_xmit_timer(tp, 1456 tcp_now - tp->t_rtttime); 1457 acked = th->th_ack - tp->snd_una; 1458 tcpstat.tcps_rcvackpack++; 1459 tcpstat.tcps_rcvackbyte += acked; 1460 ND6_HINT(tp); 1461 1462 slen = tp->t_lastm->m_len; 1463 sbdrop(&so->so_snd, acked); 1464 if (so->so_snd.sb_cc != 0) { 1465 tp->t_lastoff -= acked; 1466 if (tp->t_lastm->m_len < slen) 1467 tp->t_inoff -= 1468 (slen - tp->t_lastm->m_len); 1469 } 1470 1471 /* 1472 * We want snd_recover to track snd_una to 1473 * avoid sequence wraparound problems for 1474 * very large transfers. 1475 */ 1476 tp->snd_una = tp->snd_recover = th->th_ack; 1477 m_freem(m); 1478 1479 /* 1480 * If all outstanding data are acked, stop 1481 * retransmit timer, otherwise restart timer 1482 * using current (possibly backed-off) value. 1483 * If process is waiting for space, 1484 * wakeup/selwakeup/signal. If data 1485 * are ready to send, let tcp_output 1486 * decide between more output or persist. 1487 */ 1488 if (tp->snd_una == tp->snd_max) 1489 TCP_TIMER_DISARM(tp, TCPT_REXMT); 1490 else if (TCP_TIMER_ISARMED(tp, 1491 TCPT_PERSIST) == 0) 1492 TCP_TIMER_ARM(tp, TCPT_REXMT, 1493 tp->t_rxtcur); 1494 1495 sowwakeup(so); 1496 if (so->so_snd.sb_cc) 1497 (void) tcp_output(tp); 1498 if (tcp_saveti) 1499 m_freem(tcp_saveti); 1500 return; 1501 } 1502 } else if (th->th_ack == tp->snd_una && 1503 TAILQ_FIRST(&tp->segq) == NULL && 1504 tlen <= sbspace(&so->so_rcv)) { 1505 /* 1506 * this is a pure, in-sequence data packet 1507 * with nothing on the reassembly queue and 1508 * we have enough buffer space to take it. 1509 */ 1510 ++tcpstat.tcps_preddat; 1511 tp->rcv_nxt += tlen; 1512 tcpstat.tcps_rcvpack++; 1513 tcpstat.tcps_rcvbyte += tlen; 1514 ND6_HINT(tp); 1515 /* 1516 * Drop TCP, IP headers and TCP options then add data 1517 * to socket buffer. 1518 */ 1519 if (so->so_state & SS_CANTRCVMORE) 1520 m_freem(m); 1521 else { 1522 m_adj(m, toff + off); 1523 sbappendstream(&so->so_rcv, m); 1524 } 1525 sorwakeup(so); 1526 TCP_SETUP_ACK(tp, th); 1527 if (tp->t_flags & TF_ACKNOW) 1528 (void) tcp_output(tp); 1529 if (tcp_saveti) 1530 m_freem(tcp_saveti); 1531 return; 1532 } 1533 } 1534 1535 /* 1536 * Compute mbuf offset to TCP data segment. 1537 */ 1538 hdroptlen = toff + off; 1539 1540 /* 1541 * Calculate amount of space in receive window, 1542 * and then do TCP input processing. 1543 * Receive window is amount of space in rcv queue, 1544 * but not less than advertised window. 1545 */ 1546 { int win; 1547 1548 win = sbspace(&so->so_rcv); 1549 if (win < 0) 1550 win = 0; 1551 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 1552 } 1553 1554 switch (tp->t_state) { 1555 case TCPS_LISTEN: 1556 /* 1557 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN 1558 */ 1559 if (m->m_flags & (M_BCAST|M_MCAST)) 1560 goto drop; 1561 switch (af) { 1562 #ifdef INET6 1563 case AF_INET6: 1564 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) 1565 goto drop; 1566 break; 1567 #endif /* INET6 */ 1568 case AF_INET: 1569 if (IN_MULTICAST(ip->ip_dst.s_addr) || 1570 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 1571 goto drop; 1572 break; 1573 } 1574 break; 1575 1576 /* 1577 * If the state is SYN_SENT: 1578 * if seg contains an ACK, but not for our SYN, drop the input. 1579 * if seg contains a RST, then drop the connection. 1580 * if seg does not contain SYN, then drop it. 1581 * Otherwise this is an acceptable SYN segment 1582 * initialize tp->rcv_nxt and tp->irs 1583 * if seg contains ack then advance tp->snd_una 1584 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 1585 * arrange for segment to be acked (eventually) 1586 * continue processing rest of data/controls, beginning with URG 1587 */ 1588 case TCPS_SYN_SENT: 1589 if ((tiflags & TH_ACK) && 1590 (SEQ_LEQ(th->th_ack, tp->iss) || 1591 SEQ_GT(th->th_ack, tp->snd_max))) 1592 goto dropwithreset; 1593 if (tiflags & TH_RST) { 1594 if (tiflags & TH_ACK) 1595 tp = tcp_drop(tp, ECONNREFUSED); 1596 goto drop; 1597 } 1598 if ((tiflags & TH_SYN) == 0) 1599 goto drop; 1600 if (tiflags & TH_ACK) { 1601 tp->snd_una = tp->snd_recover = th->th_ack; 1602 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 1603 tp->snd_nxt = tp->snd_una; 1604 TCP_TIMER_DISARM(tp, TCPT_REXMT); 1605 } 1606 tp->irs = th->th_seq; 1607 tcp_rcvseqinit(tp); 1608 tp->t_flags |= TF_ACKNOW; 1609 tcp_mss_from_peer(tp, opti.maxseg); 1610 1611 /* 1612 * Initialize the initial congestion window. If we 1613 * had to retransmit the SYN, we must initialize cwnd 1614 * to 1 segment (i.e. the Loss Window). 1615 */ 1616 if (tp->t_flags & TF_SYN_REXMT) 1617 tp->snd_cwnd = tp->t_peermss; 1618 else { 1619 int ss = tcp_init_win; 1620 #ifdef INET 1621 if (inp != NULL && in_localaddr(inp->inp_faddr)) 1622 ss = tcp_init_win_local; 1623 #endif 1624 #ifdef INET6 1625 if (in6p != NULL && in6_localaddr(&in6p->in6p_faddr)) 1626 ss = tcp_init_win_local; 1627 #endif 1628 tp->snd_cwnd = TCP_INITIAL_WINDOW(ss, tp->t_peermss); 1629 } 1630 1631 tcp_rmx_rtt(tp); 1632 if (tiflags & TH_ACK) { 1633 tcpstat.tcps_connects++; 1634 soisconnected(so); 1635 tcp_established(tp); 1636 /* Do window scaling on this connection? */ 1637 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 1638 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 1639 tp->snd_scale = tp->requested_s_scale; 1640 tp->rcv_scale = tp->request_r_scale; 1641 } 1642 TCP_REASS_LOCK(tp); 1643 (void) tcp_reass(tp, NULL, (struct mbuf *)0, &tlen); 1644 TCP_REASS_UNLOCK(tp); 1645 /* 1646 * if we didn't have to retransmit the SYN, 1647 * use its rtt as our initial srtt & rtt var. 1648 */ 1649 if (tp->t_rtttime) 1650 tcp_xmit_timer(tp, tcp_now - tp->t_rtttime); 1651 } else 1652 tp->t_state = TCPS_SYN_RECEIVED; 1653 1654 /* 1655 * Advance th->th_seq to correspond to first data byte. 1656 * If data, trim to stay within window, 1657 * dropping FIN if necessary. 1658 */ 1659 th->th_seq++; 1660 if (tlen > tp->rcv_wnd) { 1661 todrop = tlen - tp->rcv_wnd; 1662 m_adj(m, -todrop); 1663 tlen = tp->rcv_wnd; 1664 tiflags &= ~TH_FIN; 1665 tcpstat.tcps_rcvpackafterwin++; 1666 tcpstat.tcps_rcvbyteafterwin += todrop; 1667 } 1668 tp->snd_wl1 = th->th_seq - 1; 1669 tp->rcv_up = th->th_seq; 1670 goto step6; 1671 1672 /* 1673 * If the state is SYN_RECEIVED: 1674 * If seg contains an ACK, but not for our SYN, drop the input 1675 * and generate an RST. See page 36, rfc793 1676 */ 1677 case TCPS_SYN_RECEIVED: 1678 if ((tiflags & TH_ACK) && 1679 (SEQ_LEQ(th->th_ack, tp->iss) || 1680 SEQ_GT(th->th_ack, tp->snd_max))) 1681 goto dropwithreset; 1682 break; 1683 } 1684 1685 /* 1686 * States other than LISTEN or SYN_SENT. 1687 * First check timestamp, if present. 1688 * Then check that at least some bytes of segment are within 1689 * receive window. If segment begins before rcv_nxt, 1690 * drop leading data (and SYN); if nothing left, just ack. 1691 * 1692 * RFC 1323 PAWS: If we have a timestamp reply on this segment 1693 * and it's less than ts_recent, drop it. 1694 */ 1695 if (opti.ts_present && (tiflags & TH_RST) == 0 && tp->ts_recent && 1696 TSTMP_LT(opti.ts_val, tp->ts_recent)) { 1697 1698 /* Check to see if ts_recent is over 24 days old. */ 1699 if ((int)(TCP_TIMESTAMP(tp) - tp->ts_recent_age) > 1700 TCP_PAWS_IDLE) { 1701 /* 1702 * Invalidate ts_recent. If this segment updates 1703 * ts_recent, the age will be reset later and ts_recent 1704 * will get a valid value. If it does not, setting 1705 * ts_recent to zero will at least satisfy the 1706 * requirement that zero be placed in the timestamp 1707 * echo reply when ts_recent isn't valid. The 1708 * age isn't reset until we get a valid ts_recent 1709 * because we don't want out-of-order segments to be 1710 * dropped when ts_recent is old. 1711 */ 1712 tp->ts_recent = 0; 1713 } else { 1714 tcpstat.tcps_rcvduppack++; 1715 tcpstat.tcps_rcvdupbyte += tlen; 1716 tcpstat.tcps_pawsdrop++; 1717 goto dropafterack; 1718 } 1719 } 1720 1721 todrop = tp->rcv_nxt - th->th_seq; 1722 if (todrop > 0) { 1723 if (tiflags & TH_SYN) { 1724 tiflags &= ~TH_SYN; 1725 th->th_seq++; 1726 if (th->th_urp > 1) 1727 th->th_urp--; 1728 else { 1729 tiflags &= ~TH_URG; 1730 th->th_urp = 0; 1731 } 1732 todrop--; 1733 } 1734 if (todrop > tlen || 1735 (todrop == tlen && (tiflags & TH_FIN) == 0)) { 1736 /* 1737 * Any valid FIN must be to the left of the window. 1738 * At this point the FIN must be a duplicate or 1739 * out of sequence; drop it. 1740 */ 1741 tiflags &= ~TH_FIN; 1742 /* 1743 * Send an ACK to resynchronize and drop any data. 1744 * But keep on processing for RST or ACK. 1745 */ 1746 tp->t_flags |= TF_ACKNOW; 1747 todrop = tlen; 1748 tcpstat.tcps_rcvdupbyte += todrop; 1749 tcpstat.tcps_rcvduppack++; 1750 } else { 1751 tcpstat.tcps_rcvpartduppack++; 1752 tcpstat.tcps_rcvpartdupbyte += todrop; 1753 } 1754 hdroptlen += todrop; /*drop from head afterwards*/ 1755 th->th_seq += todrop; 1756 tlen -= todrop; 1757 if (th->th_urp > todrop) 1758 th->th_urp -= todrop; 1759 else { 1760 tiflags &= ~TH_URG; 1761 th->th_urp = 0; 1762 } 1763 } 1764 1765 /* 1766 * If new data are received on a connection after the 1767 * user processes are gone, then RST the other end. 1768 */ 1769 if ((so->so_state & SS_NOFDREF) && 1770 tp->t_state > TCPS_CLOSE_WAIT && tlen) { 1771 tp = tcp_close(tp); 1772 tcpstat.tcps_rcvafterclose++; 1773 goto dropwithreset; 1774 } 1775 1776 /* 1777 * If segment ends after window, drop trailing data 1778 * (and PUSH and FIN); if nothing left, just ACK. 1779 */ 1780 todrop = (th->th_seq + tlen) - (tp->rcv_nxt+tp->rcv_wnd); 1781 if (todrop > 0) { 1782 tcpstat.tcps_rcvpackafterwin++; 1783 if (todrop >= tlen) { 1784 tcpstat.tcps_rcvbyteafterwin += tlen; 1785 /* 1786 * If a new connection request is received 1787 * while in TIME_WAIT, drop the old connection 1788 * and start over if the sequence numbers 1789 * are above the previous ones. 1790 * 1791 * NOTE: We will checksum the packet again, and 1792 * so we need to put the header fields back into 1793 * network order! 1794 * XXX This kind of sucks, but we don't expect 1795 * XXX this to happen very often, so maybe it 1796 * XXX doesn't matter so much. 1797 */ 1798 if (tiflags & TH_SYN && 1799 tp->t_state == TCPS_TIME_WAIT && 1800 SEQ_GT(th->th_seq, tp->rcv_nxt)) { 1801 iss = tcp_new_iss(tp, tp->snd_nxt); 1802 tp = tcp_close(tp); 1803 TCP_FIELDS_TO_NET(th); 1804 goto findpcb; 1805 } 1806 /* 1807 * If window is closed can only take segments at 1808 * window edge, and have to drop data and PUSH from 1809 * incoming segments. Continue processing, but 1810 * remember to ack. Otherwise, drop segment 1811 * and ack. 1812 */ 1813 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 1814 tp->t_flags |= TF_ACKNOW; 1815 tcpstat.tcps_rcvwinprobe++; 1816 } else 1817 goto dropafterack; 1818 } else 1819 tcpstat.tcps_rcvbyteafterwin += todrop; 1820 m_adj(m, -todrop); 1821 tlen -= todrop; 1822 tiflags &= ~(TH_PUSH|TH_FIN); 1823 } 1824 1825 /* 1826 * If last ACK falls within this segment's sequence numbers, 1827 * and the timestamp is newer, record it. 1828 */ 1829 if (opti.ts_present && TSTMP_GEQ(opti.ts_val, tp->ts_recent) && 1830 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 1831 SEQ_LT(tp->last_ack_sent, th->th_seq + tlen + 1832 ((tiflags & (TH_SYN|TH_FIN)) != 0))) { 1833 tp->ts_recent_age = TCP_TIMESTAMP(tp); 1834 tp->ts_recent = opti.ts_val; 1835 } 1836 1837 /* 1838 * If the RST bit is set examine the state: 1839 * SYN_RECEIVED STATE: 1840 * If passive open, return to LISTEN state. 1841 * If active open, inform user that connection was refused. 1842 * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES: 1843 * Inform user that connection was reset, and close tcb. 1844 * CLOSING, LAST_ACK, TIME_WAIT STATES 1845 * Close the tcb. 1846 */ 1847 if (tiflags&TH_RST) switch (tp->t_state) { 1848 1849 case TCPS_SYN_RECEIVED: 1850 so->so_error = ECONNREFUSED; 1851 goto close; 1852 1853 case TCPS_ESTABLISHED: 1854 case TCPS_FIN_WAIT_1: 1855 case TCPS_FIN_WAIT_2: 1856 case TCPS_CLOSE_WAIT: 1857 so->so_error = ECONNRESET; 1858 close: 1859 tp->t_state = TCPS_CLOSED; 1860 tcpstat.tcps_drops++; 1861 tp = tcp_close(tp); 1862 goto drop; 1863 1864 case TCPS_CLOSING: 1865 case TCPS_LAST_ACK: 1866 case TCPS_TIME_WAIT: 1867 tp = tcp_close(tp); 1868 goto drop; 1869 } 1870 1871 /* 1872 * If a SYN is in the window, then this is an 1873 * error and we send an RST and drop the connection. 1874 */ 1875 if (tiflags & TH_SYN) { 1876 tp = tcp_drop(tp, ECONNRESET); 1877 goto dropwithreset; 1878 } 1879 1880 /* 1881 * If the ACK bit is off we drop the segment and return. 1882 */ 1883 if ((tiflags & TH_ACK) == 0) { 1884 if (tp->t_flags & TF_ACKNOW) 1885 goto dropafterack; 1886 else 1887 goto drop; 1888 } 1889 1890 /* 1891 * Ack processing. 1892 */ 1893 switch (tp->t_state) { 1894 1895 /* 1896 * In SYN_RECEIVED state if the ack ACKs our SYN then enter 1897 * ESTABLISHED state and continue processing, otherwise 1898 * send an RST. 1899 */ 1900 case TCPS_SYN_RECEIVED: 1901 if (SEQ_GT(tp->snd_una, th->th_ack) || 1902 SEQ_GT(th->th_ack, tp->snd_max)) 1903 goto dropwithreset; 1904 tcpstat.tcps_connects++; 1905 soisconnected(so); 1906 tcp_established(tp); 1907 /* Do window scaling? */ 1908 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 1909 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 1910 tp->snd_scale = tp->requested_s_scale; 1911 tp->rcv_scale = tp->request_r_scale; 1912 } 1913 TCP_REASS_LOCK(tp); 1914 (void) tcp_reass(tp, NULL, (struct mbuf *)0, &tlen); 1915 TCP_REASS_UNLOCK(tp); 1916 tp->snd_wl1 = th->th_seq - 1; 1917 /* fall into ... */ 1918 1919 /* 1920 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 1921 * ACKs. If the ack is in the range 1922 * tp->snd_una < th->th_ack <= tp->snd_max 1923 * then advance tp->snd_una to th->th_ack and drop 1924 * data from the retransmission queue. If this ACK reflects 1925 * more up to date window information we update our window information. 1926 */ 1927 case TCPS_ESTABLISHED: 1928 case TCPS_FIN_WAIT_1: 1929 case TCPS_FIN_WAIT_2: 1930 case TCPS_CLOSE_WAIT: 1931 case TCPS_CLOSING: 1932 case TCPS_LAST_ACK: 1933 case TCPS_TIME_WAIT: 1934 1935 if (SEQ_LEQ(th->th_ack, tp->snd_una)) { 1936 if (tlen == 0 && tiwin == tp->snd_wnd) { 1937 tcpstat.tcps_rcvdupack++; 1938 /* 1939 * If we have outstanding data (other than 1940 * a window probe), this is a completely 1941 * duplicate ack (ie, window info didn't 1942 * change), the ack is the biggest we've 1943 * seen and we've seen exactly our rexmt 1944 * threshhold of them, assume a packet 1945 * has been dropped and retransmit it. 1946 * Kludge snd_nxt & the congestion 1947 * window so we send only this one 1948 * packet. 1949 * 1950 * We know we're losing at the current 1951 * window size so do congestion avoidance 1952 * (set ssthresh to half the current window 1953 * and pull our congestion window back to 1954 * the new ssthresh). 1955 * 1956 * Dup acks mean that packets have left the 1957 * network (they're now cached at the receiver) 1958 * so bump cwnd by the amount in the receiver 1959 * to keep a constant cwnd packets in the 1960 * network. 1961 */ 1962 if (TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 || 1963 th->th_ack != tp->snd_una) 1964 tp->t_dupacks = 0; 1965 else if (++tp->t_dupacks == tcprexmtthresh) { 1966 tcp_seq onxt = tp->snd_nxt; 1967 u_int win = 1968 min(tp->snd_wnd, tp->snd_cwnd) / 1969 2 / tp->t_segsz; 1970 if (tcp_do_newreno && SEQ_LT(th->th_ack, 1971 tp->snd_recover)) { 1972 /* 1973 * False fast retransmit after 1974 * timeout. Do not cut window. 1975 */ 1976 tp->snd_cwnd += tp->t_segsz; 1977 tp->t_dupacks = 0; 1978 (void) tcp_output(tp); 1979 goto drop; 1980 } 1981 1982 if (win < 2) 1983 win = 2; 1984 tp->snd_ssthresh = win * tp->t_segsz; 1985 tp->snd_recover = tp->snd_max; 1986 TCP_TIMER_DISARM(tp, TCPT_REXMT); 1987 tp->t_rtttime = 0; 1988 tp->snd_nxt = th->th_ack; 1989 tp->snd_cwnd = tp->t_segsz; 1990 (void) tcp_output(tp); 1991 tp->snd_cwnd = tp->snd_ssthresh + 1992 tp->t_segsz * tp->t_dupacks; 1993 if (SEQ_GT(onxt, tp->snd_nxt)) 1994 tp->snd_nxt = onxt; 1995 goto drop; 1996 } else if (tp->t_dupacks > tcprexmtthresh) { 1997 tp->snd_cwnd += tp->t_segsz; 1998 (void) tcp_output(tp); 1999 goto drop; 2000 } 2001 } else 2002 tp->t_dupacks = 0; 2003 break; 2004 } 2005 /* 2006 * If the congestion window was inflated to account 2007 * for the other side's cached packets, retract it. 2008 */ 2009 if (tcp_do_newreno == 0) { 2010 if (tp->t_dupacks >= tcprexmtthresh && 2011 tp->snd_cwnd > tp->snd_ssthresh) 2012 tp->snd_cwnd = tp->snd_ssthresh; 2013 tp->t_dupacks = 0; 2014 } else if (tp->t_dupacks >= tcprexmtthresh && 2015 tcp_newreno(tp, th) == 0) { 2016 tp->snd_cwnd = tp->snd_ssthresh; 2017 /* 2018 * Window inflation should have left us with approx. 2019 * snd_ssthresh outstanding data. But in case we 2020 * would be inclined to send a burst, better to do 2021 * it via the slow start mechanism. 2022 */ 2023 if (SEQ_SUB(tp->snd_max, th->th_ack) < tp->snd_ssthresh) 2024 tp->snd_cwnd = SEQ_SUB(tp->snd_max, th->th_ack) 2025 + tp->t_segsz; 2026 tp->t_dupacks = 0; 2027 } 2028 if (SEQ_GT(th->th_ack, tp->snd_max)) { 2029 tcpstat.tcps_rcvacktoomuch++; 2030 goto dropafterack; 2031 } 2032 acked = th->th_ack - tp->snd_una; 2033 tcpstat.tcps_rcvackpack++; 2034 tcpstat.tcps_rcvackbyte += acked; 2035 2036 /* 2037 * If we have a timestamp reply, update smoothed 2038 * round trip time. If no timestamp is present but 2039 * transmit timer is running and timed sequence 2040 * number was acked, update smoothed round trip time. 2041 * Since we now have an rtt measurement, cancel the 2042 * timer backoff (cf., Phil Karn's retransmit alg.). 2043 * Recompute the initial retransmit timer. 2044 */ 2045 if (opti.ts_present && opti.ts_ecr) 2046 tcp_xmit_timer(tp, TCP_TIMESTAMP(tp) - opti.ts_ecr + 1); 2047 else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) 2048 tcp_xmit_timer(tp, tcp_now - tp->t_rtttime); 2049 2050 /* 2051 * If all outstanding data is acked, stop retransmit 2052 * timer and remember to restart (more output or persist). 2053 * If there is more data to be acked, restart retransmit 2054 * timer, using current (possibly backed-off) value. 2055 */ 2056 if (th->th_ack == tp->snd_max) { 2057 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2058 needoutput = 1; 2059 } else if (TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) 2060 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 2061 /* 2062 * When new data is acked, open the congestion window. 2063 * If the window gives us less than ssthresh packets 2064 * in flight, open exponentially (segsz per packet). 2065 * Otherwise open linearly: segsz per window 2066 * (segsz^2 / cwnd per packet), plus a constant 2067 * fraction of a packet (segsz/8) to help larger windows 2068 * open quickly enough. 2069 */ 2070 { 2071 u_int cw = tp->snd_cwnd; 2072 u_int incr = tp->t_segsz; 2073 2074 if (cw > tp->snd_ssthresh) 2075 incr = incr * incr / cw; 2076 if (tcp_do_newreno == 0 || SEQ_GEQ(th->th_ack, tp->snd_recover)) 2077 tp->snd_cwnd = min(cw + incr, 2078 TCP_MAXWIN << tp->snd_scale); 2079 } 2080 ND6_HINT(tp); 2081 if (acked > so->so_snd.sb_cc) { 2082 tp->snd_wnd -= so->so_snd.sb_cc; 2083 sbdrop(&so->so_snd, (int)so->so_snd.sb_cc); 2084 ourfinisacked = 1; 2085 } else { 2086 int slen; 2087 2088 slen = tp->t_lastm->m_len; 2089 sbdrop(&so->so_snd, acked); 2090 tp->snd_wnd -= acked; 2091 if (so->so_snd.sb_cc != 0) { 2092 tp->t_lastoff -= acked; 2093 if (tp->t_lastm->m_len != slen) 2094 tp->t_inoff -= 2095 (slen - tp->t_lastm->m_len); 2096 } 2097 ourfinisacked = 0; 2098 } 2099 sowwakeup(so); 2100 /* 2101 * We want snd_recover to track snd_una to 2102 * avoid sequence wraparound problems for 2103 * very large transfers. 2104 */ 2105 tp->snd_una = tp->snd_recover = th->th_ack; 2106 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2107 tp->snd_nxt = tp->snd_una; 2108 2109 switch (tp->t_state) { 2110 2111 /* 2112 * In FIN_WAIT_1 STATE in addition to the processing 2113 * for the ESTABLISHED state if our FIN is now acknowledged 2114 * then enter FIN_WAIT_2. 2115 */ 2116 case TCPS_FIN_WAIT_1: 2117 if (ourfinisacked) { 2118 /* 2119 * If we can't receive any more 2120 * data, then closing user can proceed. 2121 * Starting the timer is contrary to the 2122 * specification, but if we don't get a FIN 2123 * we'll hang forever. 2124 */ 2125 if (so->so_state & SS_CANTRCVMORE) { 2126 soisdisconnected(so); 2127 if (tcp_maxidle > 0) 2128 TCP_TIMER_ARM(tp, TCPT_2MSL, 2129 tcp_maxidle); 2130 } 2131 tp->t_state = TCPS_FIN_WAIT_2; 2132 } 2133 break; 2134 2135 /* 2136 * In CLOSING STATE in addition to the processing for 2137 * the ESTABLISHED state if the ACK acknowledges our FIN 2138 * then enter the TIME-WAIT state, otherwise ignore 2139 * the segment. 2140 */ 2141 case TCPS_CLOSING: 2142 if (ourfinisacked) { 2143 tp->t_state = TCPS_TIME_WAIT; 2144 tcp_canceltimers(tp); 2145 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 2146 soisdisconnected(so); 2147 } 2148 break; 2149 2150 /* 2151 * In LAST_ACK, we may still be waiting for data to drain 2152 * and/or to be acked, as well as for the ack of our FIN. 2153 * If our FIN is now acknowledged, delete the TCB, 2154 * enter the closed state and return. 2155 */ 2156 case TCPS_LAST_ACK: 2157 if (ourfinisacked) { 2158 tp = tcp_close(tp); 2159 goto drop; 2160 } 2161 break; 2162 2163 /* 2164 * In TIME_WAIT state the only thing that should arrive 2165 * is a retransmission of the remote FIN. Acknowledge 2166 * it and restart the finack timer. 2167 */ 2168 case TCPS_TIME_WAIT: 2169 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 2170 goto dropafterack; 2171 } 2172 } 2173 2174 step6: 2175 /* 2176 * Update window information. 2177 * Don't look at window if no ACK: TAC's send garbage on first SYN. 2178 */ 2179 if ((tiflags & TH_ACK) && (SEQ_LT(tp->snd_wl1, th->th_seq) || 2180 (tp->snd_wl1 == th->th_seq && SEQ_LT(tp->snd_wl2, th->th_ack)) || 2181 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))) { 2182 /* keep track of pure window updates */ 2183 if (tlen == 0 && 2184 tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) 2185 tcpstat.tcps_rcvwinupd++; 2186 tp->snd_wnd = tiwin; 2187 tp->snd_wl1 = th->th_seq; 2188 tp->snd_wl2 = th->th_ack; 2189 if (tp->snd_wnd > tp->max_sndwnd) 2190 tp->max_sndwnd = tp->snd_wnd; 2191 needoutput = 1; 2192 } 2193 2194 /* 2195 * Process segments with URG. 2196 */ 2197 if ((tiflags & TH_URG) && th->th_urp && 2198 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2199 /* 2200 * This is a kludge, but if we receive and accept 2201 * random urgent pointers, we'll crash in 2202 * soreceive. It's hard to imagine someone 2203 * actually wanting to send this much urgent data. 2204 */ 2205 if (th->th_urp + so->so_rcv.sb_cc > sb_max) { 2206 th->th_urp = 0; /* XXX */ 2207 tiflags &= ~TH_URG; /* XXX */ 2208 goto dodata; /* XXX */ 2209 } 2210 /* 2211 * If this segment advances the known urgent pointer, 2212 * then mark the data stream. This should not happen 2213 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 2214 * a FIN has been received from the remote side. 2215 * In these states we ignore the URG. 2216 * 2217 * According to RFC961 (Assigned Protocols), 2218 * the urgent pointer points to the last octet 2219 * of urgent data. We continue, however, 2220 * to consider it to indicate the first octet 2221 * of data past the urgent section as the original 2222 * spec states (in one of two places). 2223 */ 2224 if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) { 2225 tp->rcv_up = th->th_seq + th->th_urp; 2226 so->so_oobmark = so->so_rcv.sb_cc + 2227 (tp->rcv_up - tp->rcv_nxt) - 1; 2228 if (so->so_oobmark == 0) 2229 so->so_state |= SS_RCVATMARK; 2230 sohasoutofband(so); 2231 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); 2232 } 2233 /* 2234 * Remove out of band data so doesn't get presented to user. 2235 * This can happen independent of advancing the URG pointer, 2236 * but if two URG's are pending at once, some out-of-band 2237 * data may creep in... ick. 2238 */ 2239 if (th->th_urp <= (u_int16_t) tlen 2240 #ifdef SO_OOBINLINE 2241 && (so->so_options & SO_OOBINLINE) == 0 2242 #endif 2243 ) 2244 tcp_pulloutofband(so, th, m, hdroptlen); 2245 } else 2246 /* 2247 * If no out of band data is expected, 2248 * pull receive urgent pointer along 2249 * with the receive window. 2250 */ 2251 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) 2252 tp->rcv_up = tp->rcv_nxt; 2253 dodata: /* XXX */ 2254 2255 /* 2256 * Process the segment text, merging it into the TCP sequencing queue, 2257 * and arranging for acknowledgement of receipt if necessary. 2258 * This process logically involves adjusting tp->rcv_wnd as data 2259 * is presented to the user (this happens in tcp_usrreq.c, 2260 * case PRU_RCVD). If a FIN has already been received on this 2261 * connection then we just ignore the text. 2262 */ 2263 if ((tlen || (tiflags & TH_FIN)) && 2264 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2265 /* 2266 * Insert segment ti into reassembly queue of tcp with 2267 * control block tp. Return TH_FIN if reassembly now includes 2268 * a segment with FIN. The macro form does the common case 2269 * inline (segment is the next to be received on an 2270 * established connection, and the queue is empty), 2271 * avoiding linkage into and removal from the queue and 2272 * repetition of various conversions. 2273 * Set DELACK for segments received in order, but ack 2274 * immediately when segments are out of order 2275 * (so fast retransmit can work). 2276 */ 2277 /* NOTE: this was TCP_REASS() macro, but used only once */ 2278 TCP_REASS_LOCK(tp); 2279 if (th->th_seq == tp->rcv_nxt && 2280 TAILQ_FIRST(&tp->segq) == NULL && 2281 tp->t_state == TCPS_ESTABLISHED) { 2282 TCP_SETUP_ACK(tp, th); 2283 tp->rcv_nxt += tlen; 2284 tiflags = th->th_flags & TH_FIN; 2285 tcpstat.tcps_rcvpack++; 2286 tcpstat.tcps_rcvbyte += tlen; 2287 ND6_HINT(tp); 2288 if (so->so_state & SS_CANTRCVMORE) 2289 m_freem(m); 2290 else { 2291 m_adj(m, hdroptlen); 2292 sbappendstream(&(so)->so_rcv, m); 2293 } 2294 sorwakeup(so); 2295 } else { 2296 m_adj(m, hdroptlen); 2297 tiflags = tcp_reass(tp, th, m, &tlen); 2298 tp->t_flags |= TF_ACKNOW; 2299 } 2300 TCP_REASS_UNLOCK(tp); 2301 2302 /* 2303 * Note the amount of data that peer has sent into 2304 * our window, in order to estimate the sender's 2305 * buffer size. 2306 */ 2307 len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); 2308 } else { 2309 m_freem(m); 2310 m = NULL; 2311 tiflags &= ~TH_FIN; 2312 } 2313 2314 /* 2315 * If FIN is received ACK the FIN and let the user know 2316 * that the connection is closing. Ignore a FIN received before 2317 * the connection is fully established. 2318 */ 2319 if ((tiflags & TH_FIN) && TCPS_HAVEESTABLISHED(tp->t_state)) { 2320 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2321 socantrcvmore(so); 2322 tp->t_flags |= TF_ACKNOW; 2323 tp->rcv_nxt++; 2324 } 2325 switch (tp->t_state) { 2326 2327 /* 2328 * In ESTABLISHED STATE enter the CLOSE_WAIT state. 2329 */ 2330 case TCPS_ESTABLISHED: 2331 tp->t_state = TCPS_CLOSE_WAIT; 2332 break; 2333 2334 /* 2335 * If still in FIN_WAIT_1 STATE FIN has not been acked so 2336 * enter the CLOSING state. 2337 */ 2338 case TCPS_FIN_WAIT_1: 2339 tp->t_state = TCPS_CLOSING; 2340 break; 2341 2342 /* 2343 * In FIN_WAIT_2 state enter the TIME_WAIT state, 2344 * starting the time-wait timer, turning off the other 2345 * standard timers. 2346 */ 2347 case TCPS_FIN_WAIT_2: 2348 tp->t_state = TCPS_TIME_WAIT; 2349 tcp_canceltimers(tp); 2350 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 2351 soisdisconnected(so); 2352 break; 2353 2354 /* 2355 * In TIME_WAIT state restart the 2 MSL time_wait timer. 2356 */ 2357 case TCPS_TIME_WAIT: 2358 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 2359 break; 2360 } 2361 } 2362 #ifdef TCP_DEBUG 2363 if (so->so_options & SO_DEBUG) 2364 tcp_trace(TA_INPUT, ostate, tp, tcp_saveti, 0); 2365 #endif 2366 2367 /* 2368 * Return any desired output. 2369 */ 2370 if (needoutput || (tp->t_flags & TF_ACKNOW)) 2371 (void) tcp_output(tp); 2372 if (tcp_saveti) 2373 m_freem(tcp_saveti); 2374 return; 2375 2376 badsyn: 2377 /* 2378 * Received a bad SYN. Increment counters and dropwithreset. 2379 */ 2380 tcpstat.tcps_badsyn++; 2381 tp = NULL; 2382 goto dropwithreset; 2383 2384 dropafterack: 2385 /* 2386 * Generate an ACK dropping incoming segment if it occupies 2387 * sequence space, where the ACK reflects our state. 2388 */ 2389 if (tiflags & TH_RST) 2390 goto drop; 2391 m_freem(m); 2392 tp->t_flags |= TF_ACKNOW; 2393 (void) tcp_output(tp); 2394 if (tcp_saveti) 2395 m_freem(tcp_saveti); 2396 return; 2397 2398 dropwithreset_ratelim: 2399 /* 2400 * We may want to rate-limit RSTs in certain situations, 2401 * particularly if we are sending an RST in response to 2402 * an attempt to connect to or otherwise communicate with 2403 * a port for which we have no socket. 2404 */ 2405 if (ppsratecheck(&tcp_rst_ppslim_last, &tcp_rst_ppslim_count, 2406 tcp_rst_ppslim) == 0) { 2407 /* XXX stat */ 2408 goto drop; 2409 } 2410 /* ...fall into dropwithreset... */ 2411 2412 dropwithreset: 2413 /* 2414 * Generate a RST, dropping incoming segment. 2415 * Make ACK acceptable to originator of segment. 2416 */ 2417 if (tiflags & TH_RST) 2418 goto drop; 2419 2420 switch (af) { 2421 #ifdef INET6 2422 case AF_INET6: 2423 /* For following calls to tcp_respond */ 2424 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) 2425 goto drop; 2426 break; 2427 #endif /* INET6 */ 2428 case AF_INET: 2429 if (IN_MULTICAST(ip->ip_dst.s_addr) || 2430 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 2431 goto drop; 2432 } 2433 2434 if (tiflags & TH_ACK) 2435 (void)tcp_respond(tp, m, m, th, (tcp_seq)0, th->th_ack, TH_RST); 2436 else { 2437 if (tiflags & TH_SYN) 2438 tlen++; 2439 (void)tcp_respond(tp, m, m, th, th->th_seq + tlen, (tcp_seq)0, 2440 TH_RST|TH_ACK); 2441 } 2442 if (tcp_saveti) 2443 m_freem(tcp_saveti); 2444 return; 2445 2446 badcsum: 2447 tcpstat.tcps_rcvbadsum++; 2448 drop: 2449 /* 2450 * Drop space held by incoming segment and return. 2451 */ 2452 if (tp) { 2453 if (tp->t_inpcb) 2454 so = tp->t_inpcb->inp_socket; 2455 #ifdef INET6 2456 else if (tp->t_in6pcb) 2457 so = tp->t_in6pcb->in6p_socket; 2458 #endif 2459 else 2460 so = NULL; 2461 #ifdef TCP_DEBUG 2462 if (so && (so->so_options & SO_DEBUG) != 0) 2463 tcp_trace(TA_DROP, ostate, tp, tcp_saveti, 0); 2464 #endif 2465 } 2466 if (tcp_saveti) 2467 m_freem(tcp_saveti); 2468 m_freem(m); 2469 return; 2470 } 2471 2472 void 2473 tcp_dooptions(tp, cp, cnt, th, oi) 2474 struct tcpcb *tp; 2475 u_char *cp; 2476 int cnt; 2477 struct tcphdr *th; 2478 struct tcp_opt_info *oi; 2479 { 2480 u_int16_t mss; 2481 int opt, optlen; 2482 2483 for (; cnt > 0; cnt -= optlen, cp += optlen) { 2484 opt = cp[0]; 2485 if (opt == TCPOPT_EOL) 2486 break; 2487 if (opt == TCPOPT_NOP) 2488 optlen = 1; 2489 else { 2490 if (cnt < 2) 2491 break; 2492 optlen = cp[1]; 2493 if (optlen < 2 || optlen > cnt) 2494 break; 2495 } 2496 switch (opt) { 2497 2498 default: 2499 continue; 2500 2501 case TCPOPT_MAXSEG: 2502 if (optlen != TCPOLEN_MAXSEG) 2503 continue; 2504 if (!(th->th_flags & TH_SYN)) 2505 continue; 2506 bcopy(cp + 2, &mss, sizeof(mss)); 2507 oi->maxseg = ntohs(mss); 2508 break; 2509 2510 case TCPOPT_WINDOW: 2511 if (optlen != TCPOLEN_WINDOW) 2512 continue; 2513 if (!(th->th_flags & TH_SYN)) 2514 continue; 2515 tp->t_flags |= TF_RCVD_SCALE; 2516 tp->requested_s_scale = cp[2]; 2517 if (tp->requested_s_scale > TCP_MAX_WINSHIFT) { 2518 #if 0 /*XXX*/ 2519 char *p; 2520 2521 if (ip) 2522 p = ntohl(ip->ip_src); 2523 #ifdef INET6 2524 else if (ip6) 2525 p = ip6_sprintf(&ip6->ip6_src); 2526 #endif 2527 else 2528 p = "(unknown)"; 2529 log(LOG_ERR, "TCP: invalid wscale %d from %s, " 2530 "assuming %d\n", 2531 tp->requested_s_scale, p, 2532 TCP_MAX_WINSHIFT); 2533 #else 2534 log(LOG_ERR, "TCP: invalid wscale %d, " 2535 "assuming %d\n", 2536 tp->requested_s_scale, 2537 TCP_MAX_WINSHIFT); 2538 #endif 2539 tp->requested_s_scale = TCP_MAX_WINSHIFT; 2540 } 2541 break; 2542 2543 case TCPOPT_TIMESTAMP: 2544 if (optlen != TCPOLEN_TIMESTAMP) 2545 continue; 2546 oi->ts_present = 1; 2547 bcopy(cp + 2, &oi->ts_val, sizeof(oi->ts_val)); 2548 NTOHL(oi->ts_val); 2549 bcopy(cp + 6, &oi->ts_ecr, sizeof(oi->ts_ecr)); 2550 NTOHL(oi->ts_ecr); 2551 2552 /* 2553 * A timestamp received in a SYN makes 2554 * it ok to send timestamp requests and replies. 2555 */ 2556 if (th->th_flags & TH_SYN) { 2557 tp->t_flags |= TF_RCVD_TSTMP; 2558 tp->ts_recent = oi->ts_val; 2559 tp->ts_recent_age = TCP_TIMESTAMP(tp); 2560 } 2561 break; 2562 case TCPOPT_SACK_PERMITTED: 2563 if (optlen != TCPOLEN_SACK_PERMITTED) 2564 continue; 2565 if (!(th->th_flags & TH_SYN)) 2566 continue; 2567 tp->t_flags &= ~TF_CANT_TXSACK; 2568 break; 2569 2570 case TCPOPT_SACK: 2571 if (tp->t_flags & TF_IGNR_RXSACK) 2572 continue; 2573 if (optlen % 8 != 2 || optlen < 10) 2574 continue; 2575 cp += 2; 2576 optlen -= 2; 2577 for (; optlen > 0; cp -= 8, optlen -= 8) { 2578 tcp_seq lwe, rwe; 2579 bcopy((char *)cp, (char *) &lwe, sizeof(lwe)); 2580 NTOHL(lwe); 2581 bcopy((char *)cp, (char *) &rwe, sizeof(rwe)); 2582 NTOHL(rwe); 2583 /* tcp_mark_sacked(tp, lwe, rwe); */ 2584 } 2585 break; 2586 } 2587 } 2588 } 2589 2590 /* 2591 * Pull out of band byte out of a segment so 2592 * it doesn't appear in the user's data queue. 2593 * It is still reflected in the segment length for 2594 * sequencing purposes. 2595 */ 2596 void 2597 tcp_pulloutofband(so, th, m, off) 2598 struct socket *so; 2599 struct tcphdr *th; 2600 struct mbuf *m; 2601 int off; 2602 { 2603 int cnt = off + th->th_urp - 1; 2604 2605 while (cnt >= 0) { 2606 if (m->m_len > cnt) { 2607 char *cp = mtod(m, caddr_t) + cnt; 2608 struct tcpcb *tp = sototcpcb(so); 2609 2610 tp->t_iobc = *cp; 2611 tp->t_oobflags |= TCPOOB_HAVEDATA; 2612 bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); 2613 m->m_len--; 2614 return; 2615 } 2616 cnt -= m->m_len; 2617 m = m->m_next; 2618 if (m == 0) 2619 break; 2620 } 2621 panic("tcp_pulloutofband"); 2622 } 2623 2624 /* 2625 * Collect new round-trip time estimate 2626 * and update averages and current timeout. 2627 */ 2628 void 2629 tcp_xmit_timer(tp, rtt) 2630 struct tcpcb *tp; 2631 uint32_t rtt; 2632 { 2633 int32_t delta; 2634 2635 tcpstat.tcps_rttupdated++; 2636 if (tp->t_srtt != 0) { 2637 /* 2638 * srtt is stored as fixed point with 3 bits after the 2639 * binary point (i.e., scaled by 8). The following magic 2640 * is equivalent to the smoothing algorithm in rfc793 with 2641 * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed 2642 * point). Adjust rtt to origin 0. 2643 */ 2644 delta = (rtt << 2) - (tp->t_srtt >> TCP_RTT_SHIFT); 2645 if ((tp->t_srtt += delta) <= 0) 2646 tp->t_srtt = 1 << 2; 2647 /* 2648 * We accumulate a smoothed rtt variance (actually, a 2649 * smoothed mean difference), then set the retransmit 2650 * timer to smoothed rtt + 4 times the smoothed variance. 2651 * rttvar is stored as fixed point with 2 bits after the 2652 * binary point (scaled by 4). The following is 2653 * equivalent to rfc793 smoothing with an alpha of .75 2654 * (rttvar = rttvar*3/4 + |delta| / 4). This replaces 2655 * rfc793's wired-in beta. 2656 */ 2657 if (delta < 0) 2658 delta = -delta; 2659 delta -= (tp->t_rttvar >> TCP_RTTVAR_SHIFT); 2660 if ((tp->t_rttvar += delta) <= 0) 2661 tp->t_rttvar = 1 << 2; 2662 } else { 2663 /* 2664 * No rtt measurement yet - use the unsmoothed rtt. 2665 * Set the variance to half the rtt (so our first 2666 * retransmit happens at 3*rtt). 2667 */ 2668 tp->t_srtt = rtt << (TCP_RTT_SHIFT + 2); 2669 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT + 2 - 1); 2670 } 2671 tp->t_rtttime = 0; 2672 tp->t_rxtshift = 0; 2673 2674 /* 2675 * the retransmit should happen at rtt + 4 * rttvar. 2676 * Because of the way we do the smoothing, srtt and rttvar 2677 * will each average +1/2 tick of bias. When we compute 2678 * the retransmit timer, we want 1/2 tick of rounding and 2679 * 1 extra tick because of +-1/2 tick uncertainty in the 2680 * firing of the timer. The bias will give us exactly the 2681 * 1.5 tick we need. But, because the bias is 2682 * statistical, we have to test that we don't drop below 2683 * the minimum feasible timer (which is 2 ticks). 2684 */ 2685 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), 2686 max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX); 2687 2688 /* 2689 * We received an ack for a packet that wasn't retransmitted; 2690 * it is probably safe to discard any error indications we've 2691 * received recently. This isn't quite right, but close enough 2692 * for now (a route might have failed after we sent a segment, 2693 * and the return path might not be symmetrical). 2694 */ 2695 tp->t_softerror = 0; 2696 } 2697 2698 /* 2699 * Checks for partial ack. If partial ack arrives, force the retransmission 2700 * of the next unacknowledged segment, do not clear tp->t_dupacks, and return 2701 * 1. By setting snd_nxt to th_ack, this forces retransmission timer to 2702 * be started again. If the ack advances at least to tp->snd_recover, return 0. 2703 */ 2704 int 2705 tcp_newreno(tp, th) 2706 struct tcpcb *tp; 2707 struct tcphdr *th; 2708 { 2709 tcp_seq onxt = tp->snd_nxt; 2710 u_long ocwnd = tp->snd_cwnd; 2711 2712 if (SEQ_LT(th->th_ack, tp->snd_recover)) { 2713 /* 2714 * snd_una has not yet been updated and the socket's send 2715 * buffer has not yet drained off the ACK'd data, so we 2716 * have to leave snd_una as it was to get the correct data 2717 * offset in tcp_output(). 2718 */ 2719 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2720 tp->t_rtttime = 0; 2721 tp->snd_nxt = th->th_ack; 2722 /* 2723 * Set snd_cwnd to one segment beyond ACK'd offset. snd_una 2724 * is not yet updated when we're called. 2725 */ 2726 tp->snd_cwnd = tp->t_segsz + (th->th_ack - tp->snd_una); 2727 (void) tcp_output(tp); 2728 tp->snd_cwnd = ocwnd; 2729 if (SEQ_GT(onxt, tp->snd_nxt)) 2730 tp->snd_nxt = onxt; 2731 /* 2732 * Partial window deflation. Relies on fact that tp->snd_una 2733 * not updated yet. 2734 */ 2735 tp->snd_cwnd -= (th->th_ack - tp->snd_una - tp->t_segsz); 2736 return 1; 2737 } 2738 return 0; 2739 } 2740 2741 2742 /* 2743 * TCP compressed state engine. Currently used to hold compressed 2744 * state for SYN_RECEIVED. 2745 */ 2746 2747 u_long syn_cache_count; 2748 u_int32_t syn_hash1, syn_hash2; 2749 2750 #define SYN_HASH(sa, sp, dp) \ 2751 ((((sa)->s_addr^syn_hash1)*(((((u_int32_t)(dp))<<16) + \ 2752 ((u_int32_t)(sp)))^syn_hash2))) 2753 #ifndef INET6 2754 #define SYN_HASHALL(hash, src, dst) \ 2755 do { \ 2756 hash = SYN_HASH(&((struct sockaddr_in *)(src))->sin_addr, \ 2757 ((struct sockaddr_in *)(src))->sin_port, \ 2758 ((struct sockaddr_in *)(dst))->sin_port); \ 2759 } while (/*CONSTCOND*/ 0) 2760 #else 2761 #define SYN_HASH6(sa, sp, dp) \ 2762 ((((sa)->s6_addr32[0] ^ (sa)->s6_addr32[3] ^ syn_hash1) * \ 2763 (((((u_int32_t)(dp))<<16) + ((u_int32_t)(sp)))^syn_hash2)) \ 2764 & 0x7fffffff) 2765 2766 #define SYN_HASHALL(hash, src, dst) \ 2767 do { \ 2768 switch ((src)->sa_family) { \ 2769 case AF_INET: \ 2770 hash = SYN_HASH(&((struct sockaddr_in *)(src))->sin_addr, \ 2771 ((struct sockaddr_in *)(src))->sin_port, \ 2772 ((struct sockaddr_in *)(dst))->sin_port); \ 2773 break; \ 2774 case AF_INET6: \ 2775 hash = SYN_HASH6(&((struct sockaddr_in6 *)(src))->sin6_addr, \ 2776 ((struct sockaddr_in6 *)(src))->sin6_port, \ 2777 ((struct sockaddr_in6 *)(dst))->sin6_port); \ 2778 break; \ 2779 default: \ 2780 hash = 0; \ 2781 } \ 2782 } while (/*CONSTCOND*/0) 2783 #endif /* INET6 */ 2784 2785 #define SYN_CACHE_RM(sc) \ 2786 do { \ 2787 TAILQ_REMOVE(&tcp_syn_cache[(sc)->sc_bucketidx].sch_bucket, \ 2788 (sc), sc_bucketq); \ 2789 (sc)->sc_tp = NULL; \ 2790 LIST_REMOVE((sc), sc_tpq); \ 2791 tcp_syn_cache[(sc)->sc_bucketidx].sch_length--; \ 2792 callout_stop(&(sc)->sc_timer); \ 2793 syn_cache_count--; \ 2794 } while (/*CONSTCOND*/0) 2795 2796 #define SYN_CACHE_PUT(sc) \ 2797 do { \ 2798 if ((sc)->sc_ipopts) \ 2799 (void) m_free((sc)->sc_ipopts); \ 2800 if ((sc)->sc_route4.ro_rt != NULL) \ 2801 RTFREE((sc)->sc_route4.ro_rt); \ 2802 if (callout_invoking(&(sc)->sc_timer)) \ 2803 (sc)->sc_flags |= SCF_DEAD; \ 2804 else \ 2805 pool_put(&syn_cache_pool, (sc)); \ 2806 } while (/*CONSTCOND*/0) 2807 2808 struct pool syn_cache_pool; 2809 2810 /* 2811 * We don't estimate RTT with SYNs, so each packet starts with the default 2812 * RTT and each timer step has a fixed timeout value. 2813 */ 2814 #define SYN_CACHE_TIMER_ARM(sc) \ 2815 do { \ 2816 TCPT_RANGESET((sc)->sc_rxtcur, \ 2817 TCPTV_SRTTDFLT * tcp_backoff[(sc)->sc_rxtshift], TCPTV_MIN, \ 2818 TCPTV_REXMTMAX); \ 2819 callout_reset(&(sc)->sc_timer, \ 2820 (sc)->sc_rxtcur * (hz / PR_SLOWHZ), syn_cache_timer, (sc)); \ 2821 } while (/*CONSTCOND*/0) 2822 2823 #define SYN_CACHE_TIMESTAMP(sc) (tcp_now - (sc)->sc_timebase) 2824 2825 void 2826 syn_cache_init() 2827 { 2828 int i; 2829 2830 /* Initialize the hash buckets. */ 2831 for (i = 0; i < tcp_syn_cache_size; i++) 2832 TAILQ_INIT(&tcp_syn_cache[i].sch_bucket); 2833 2834 /* Initialize the syn cache pool. */ 2835 pool_init(&syn_cache_pool, sizeof(struct syn_cache), 0, 0, 0, 2836 "synpl", NULL); 2837 } 2838 2839 void 2840 syn_cache_insert(sc, tp) 2841 struct syn_cache *sc; 2842 struct tcpcb *tp; 2843 { 2844 struct syn_cache_head *scp; 2845 struct syn_cache *sc2; 2846 int s; 2847 2848 /* 2849 * If there are no entries in the hash table, reinitialize 2850 * the hash secrets. 2851 */ 2852 if (syn_cache_count == 0) { 2853 struct timeval tv; 2854 microtime(&tv); 2855 syn_hash1 = arc4random() ^ (u_long)≻ 2856 syn_hash2 = arc4random() ^ tv.tv_usec; 2857 } 2858 2859 SYN_HASHALL(sc->sc_hash, &sc->sc_src.sa, &sc->sc_dst.sa); 2860 sc->sc_bucketidx = sc->sc_hash % tcp_syn_cache_size; 2861 scp = &tcp_syn_cache[sc->sc_bucketidx]; 2862 2863 /* 2864 * Make sure that we don't overflow the per-bucket 2865 * limit or the total cache size limit. 2866 */ 2867 s = splsoftnet(); 2868 if (scp->sch_length >= tcp_syn_bucket_limit) { 2869 tcpstat.tcps_sc_bucketoverflow++; 2870 /* 2871 * The bucket is full. Toss the oldest element in the 2872 * bucket. This will be the first entry in the bucket. 2873 */ 2874 sc2 = TAILQ_FIRST(&scp->sch_bucket); 2875 #ifdef DIAGNOSTIC 2876 /* 2877 * This should never happen; we should always find an 2878 * entry in our bucket. 2879 */ 2880 if (sc2 == NULL) 2881 panic("syn_cache_insert: bucketoverflow: impossible"); 2882 #endif 2883 SYN_CACHE_RM(sc2); 2884 SYN_CACHE_PUT(sc2); 2885 } else if (syn_cache_count >= tcp_syn_cache_limit) { 2886 struct syn_cache_head *scp2, *sce; 2887 2888 tcpstat.tcps_sc_overflowed++; 2889 /* 2890 * The cache is full. Toss the oldest entry in the 2891 * first non-empty bucket we can find. 2892 * 2893 * XXX We would really like to toss the oldest 2894 * entry in the cache, but we hope that this 2895 * condition doesn't happen very often. 2896 */ 2897 scp2 = scp; 2898 if (TAILQ_EMPTY(&scp2->sch_bucket)) { 2899 sce = &tcp_syn_cache[tcp_syn_cache_size]; 2900 for (++scp2; scp2 != scp; scp2++) { 2901 if (scp2 >= sce) 2902 scp2 = &tcp_syn_cache[0]; 2903 if (! TAILQ_EMPTY(&scp2->sch_bucket)) 2904 break; 2905 } 2906 #ifdef DIAGNOSTIC 2907 /* 2908 * This should never happen; we should always find a 2909 * non-empty bucket. 2910 */ 2911 if (scp2 == scp) 2912 panic("syn_cache_insert: cacheoverflow: " 2913 "impossible"); 2914 #endif 2915 } 2916 sc2 = TAILQ_FIRST(&scp2->sch_bucket); 2917 SYN_CACHE_RM(sc2); 2918 SYN_CACHE_PUT(sc2); 2919 } 2920 2921 /* 2922 * Initialize the entry's timer. 2923 */ 2924 sc->sc_rxttot = 0; 2925 sc->sc_rxtshift = 0; 2926 SYN_CACHE_TIMER_ARM(sc); 2927 2928 /* Link it from tcpcb entry */ 2929 LIST_INSERT_HEAD(&tp->t_sc, sc, sc_tpq); 2930 2931 /* Put it into the bucket. */ 2932 TAILQ_INSERT_TAIL(&scp->sch_bucket, sc, sc_bucketq); 2933 scp->sch_length++; 2934 syn_cache_count++; 2935 2936 tcpstat.tcps_sc_added++; 2937 splx(s); 2938 } 2939 2940 /* 2941 * Walk the timer queues, looking for SYN,ACKs that need to be retransmitted. 2942 * If we have retransmitted an entry the maximum number of times, expire 2943 * that entry. 2944 */ 2945 void 2946 syn_cache_timer(void *arg) 2947 { 2948 struct syn_cache *sc = arg; 2949 int s; 2950 2951 s = splsoftnet(); 2952 callout_ack(&sc->sc_timer); 2953 2954 if (__predict_false(sc->sc_flags & SCF_DEAD)) { 2955 tcpstat.tcps_sc_delayed_free++; 2956 pool_put(&syn_cache_pool, sc); 2957 splx(s); 2958 return; 2959 } 2960 2961 if (__predict_false(sc->sc_rxtshift == TCP_MAXRXTSHIFT)) { 2962 /* Drop it -- too many retransmissions. */ 2963 goto dropit; 2964 } 2965 2966 /* 2967 * Compute the total amount of time this entry has 2968 * been on a queue. If this entry has been on longer 2969 * than the keep alive timer would allow, expire it. 2970 */ 2971 sc->sc_rxttot += sc->sc_rxtcur; 2972 if (sc->sc_rxttot >= TCPTV_KEEP_INIT) 2973 goto dropit; 2974 2975 tcpstat.tcps_sc_retransmitted++; 2976 (void) syn_cache_respond(sc, NULL); 2977 2978 /* Advance the timer back-off. */ 2979 sc->sc_rxtshift++; 2980 SYN_CACHE_TIMER_ARM(sc); 2981 2982 splx(s); 2983 return; 2984 2985 dropit: 2986 tcpstat.tcps_sc_timed_out++; 2987 SYN_CACHE_RM(sc); 2988 SYN_CACHE_PUT(sc); 2989 splx(s); 2990 } 2991 2992 /* 2993 * Remove syn cache created by the specified tcb entry, 2994 * because this does not make sense to keep them 2995 * (if there's no tcb entry, syn cache entry will never be used) 2996 */ 2997 void 2998 syn_cache_cleanup(tp) 2999 struct tcpcb *tp; 3000 { 3001 struct syn_cache *sc, *nsc; 3002 int s; 3003 3004 s = splsoftnet(); 3005 3006 for (sc = LIST_FIRST(&tp->t_sc); sc != NULL; sc = nsc) { 3007 nsc = LIST_NEXT(sc, sc_tpq); 3008 3009 #ifdef DIAGNOSTIC 3010 if (sc->sc_tp != tp) 3011 panic("invalid sc_tp in syn_cache_cleanup"); 3012 #endif 3013 SYN_CACHE_RM(sc); 3014 SYN_CACHE_PUT(sc); 3015 } 3016 /* just for safety */ 3017 LIST_INIT(&tp->t_sc); 3018 3019 splx(s); 3020 } 3021 3022 /* 3023 * Find an entry in the syn cache. 3024 */ 3025 struct syn_cache * 3026 syn_cache_lookup(src, dst, headp) 3027 struct sockaddr *src; 3028 struct sockaddr *dst; 3029 struct syn_cache_head **headp; 3030 { 3031 struct syn_cache *sc; 3032 struct syn_cache_head *scp; 3033 u_int32_t hash; 3034 int s; 3035 3036 SYN_HASHALL(hash, src, dst); 3037 3038 scp = &tcp_syn_cache[hash % tcp_syn_cache_size]; 3039 *headp = scp; 3040 s = splsoftnet(); 3041 for (sc = TAILQ_FIRST(&scp->sch_bucket); sc != NULL; 3042 sc = TAILQ_NEXT(sc, sc_bucketq)) { 3043 if (sc->sc_hash != hash) 3044 continue; 3045 if (!bcmp(&sc->sc_src, src, src->sa_len) && 3046 !bcmp(&sc->sc_dst, dst, dst->sa_len)) { 3047 splx(s); 3048 return (sc); 3049 } 3050 } 3051 splx(s); 3052 return (NULL); 3053 } 3054 3055 /* 3056 * This function gets called when we receive an ACK for a 3057 * socket in the LISTEN state. We look up the connection 3058 * in the syn cache, and if its there, we pull it out of 3059 * the cache and turn it into a full-blown connection in 3060 * the SYN-RECEIVED state. 3061 * 3062 * The return values may not be immediately obvious, and their effects 3063 * can be subtle, so here they are: 3064 * 3065 * NULL SYN was not found in cache; caller should drop the 3066 * packet and send an RST. 3067 * 3068 * -1 We were unable to create the new connection, and are 3069 * aborting it. An ACK,RST is being sent to the peer 3070 * (unless we got screwey sequence numbners; see below), 3071 * because the 3-way handshake has been completed. Caller 3072 * should not free the mbuf, since we may be using it. If 3073 * we are not, we will free it. 3074 * 3075 * Otherwise, the return value is a pointer to the new socket 3076 * associated with the connection. 3077 */ 3078 struct socket * 3079 syn_cache_get(src, dst, th, hlen, tlen, so, m) 3080 struct sockaddr *src; 3081 struct sockaddr *dst; 3082 struct tcphdr *th; 3083 unsigned int hlen, tlen; 3084 struct socket *so; 3085 struct mbuf *m; 3086 { 3087 struct syn_cache *sc; 3088 struct syn_cache_head *scp; 3089 struct inpcb *inp = NULL; 3090 #ifdef INET6 3091 struct in6pcb *in6p = NULL; 3092 #endif 3093 struct tcpcb *tp = 0; 3094 struct mbuf *am; 3095 int s; 3096 struct socket *oso; 3097 3098 s = splsoftnet(); 3099 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 3100 splx(s); 3101 return (NULL); 3102 } 3103 3104 /* 3105 * Verify the sequence and ack numbers. Try getting the correct 3106 * response again. 3107 */ 3108 if ((th->th_ack != sc->sc_iss + 1) || 3109 SEQ_LEQ(th->th_seq, sc->sc_irs) || 3110 SEQ_GT(th->th_seq, sc->sc_irs + 1 + sc->sc_win)) { 3111 (void) syn_cache_respond(sc, m); 3112 splx(s); 3113 return ((struct socket *)(-1)); 3114 } 3115 3116 /* Remove this cache entry */ 3117 SYN_CACHE_RM(sc); 3118 splx(s); 3119 3120 /* 3121 * Ok, create the full blown connection, and set things up 3122 * as they would have been set up if we had created the 3123 * connection when the SYN arrived. If we can't create 3124 * the connection, abort it. 3125 */ 3126 /* 3127 * inp still has the OLD in_pcb stuff, set the 3128 * v6-related flags on the new guy, too. This is 3129 * done particularly for the case where an AF_INET6 3130 * socket is bound only to a port, and a v4 connection 3131 * comes in on that port. 3132 * we also copy the flowinfo from the original pcb 3133 * to the new one. 3134 */ 3135 oso = so; 3136 so = sonewconn(so, SS_ISCONNECTED); 3137 if (so == NULL) 3138 goto resetandabort; 3139 3140 switch (so->so_proto->pr_domain->dom_family) { 3141 #ifdef INET 3142 case AF_INET: 3143 inp = sotoinpcb(so); 3144 break; 3145 #endif 3146 #ifdef INET6 3147 case AF_INET6: 3148 in6p = sotoin6pcb(so); 3149 break; 3150 #endif 3151 } 3152 switch (src->sa_family) { 3153 #ifdef INET 3154 case AF_INET: 3155 if (inp) { 3156 struct in_ifaddr *ia; 3157 inp->inp_laddr = ((struct sockaddr_in *)dst)->sin_addr; 3158 inp->inp_lport = ((struct sockaddr_in *)dst)->sin_port; 3159 inp->inp_options = ip_srcroute(); 3160 INADDR_TO_IA(inp->inp_laddr, ia); 3161 KASSERT(ia != NULL); 3162 KASSERT(inp->inp_ia == NULL); 3163 inp->inp_ia = ia; 3164 LIST_INSERT_HEAD(&ia->ia_inpcbs, inp, inp_ialink); 3165 IFAREF(&ia->ia_ifa); 3166 in_pcbstate(inp, INP_BOUND); 3167 if (inp->inp_options == NULL) { 3168 inp->inp_options = sc->sc_ipopts; 3169 sc->sc_ipopts = NULL; 3170 } 3171 } 3172 #ifdef INET6 3173 else if (in6p) { 3174 /* IPv4 packet to AF_INET6 socket */ 3175 bzero(&in6p->in6p_laddr, sizeof(in6p->in6p_laddr)); 3176 in6p->in6p_laddr.s6_addr16[5] = htons(0xffff); 3177 bcopy(&((struct sockaddr_in *)dst)->sin_addr, 3178 &in6p->in6p_laddr.s6_addr32[3], 3179 sizeof(((struct sockaddr_in *)dst)->sin_addr)); 3180 in6p->in6p_lport = ((struct sockaddr_in *)dst)->sin_port; 3181 in6totcpcb(in6p)->t_family = AF_INET; 3182 if (sotoin6pcb(oso)->in6p_flags & IN6P_IPV6_V6ONLY) 3183 in6p->in6p_flags |= IN6P_IPV6_V6ONLY; 3184 else 3185 in6p->in6p_flags &= ~IN6P_IPV6_V6ONLY; 3186 } 3187 #endif 3188 break; 3189 #endif 3190 #ifdef INET6 3191 case AF_INET6: 3192 if (in6p) { 3193 in6p->in6p_laddr = ((struct sockaddr_in6 *)dst)->sin6_addr; 3194 in6p->in6p_lport = ((struct sockaddr_in6 *)dst)->sin6_port; 3195 #if 0 3196 in6p->in6p_flowinfo = ip6->ip6_flow & IPV6_FLOWINFO_MASK; 3197 /*inp->inp_options = ip6_srcroute();*/ /* soon. */ 3198 #endif 3199 } 3200 break; 3201 #endif 3202 } 3203 #ifdef INET6 3204 if (in6p && in6totcpcb(in6p)->t_family == AF_INET6 && sotoinpcb(oso)) { 3205 struct in6pcb *oin6p = sotoin6pcb(oso); 3206 /* inherit socket options from the listening socket */ 3207 in6p->in6p_flags |= (oin6p->in6p_flags & IN6P_CONTROLOPTS); 3208 if (in6p->in6p_flags & IN6P_CONTROLOPTS) { 3209 m_freem(in6p->in6p_options); 3210 in6p->in6p_options = 0; 3211 } 3212 ip6_savecontrol(in6p, &in6p->in6p_options, 3213 mtod(m, struct ip6_hdr *), m); 3214 } 3215 #endif 3216 3217 #ifdef IPSEC 3218 /* 3219 * we make a copy of policy, instead of sharing the policy, 3220 * for better behavior in terms of SA lookup and dead SA removal. 3221 */ 3222 if (inp) { 3223 /* copy old policy into new socket's */ 3224 if (ipsec_copy_pcbpolicy(sotoinpcb(oso)->inp_sp, inp->inp_sp)) 3225 printf("tcp_input: could not copy policy\n"); 3226 } 3227 #ifdef INET6 3228 else if (in6p) { 3229 /* copy old policy into new socket's */ 3230 if (ipsec_copy_pcbpolicy(sotoin6pcb(oso)->in6p_sp, 3231 in6p->in6p_sp)) 3232 printf("tcp_input: could not copy policy\n"); 3233 } 3234 #endif 3235 #endif 3236 3237 /* 3238 * Give the new socket our cached route reference. 3239 */ 3240 if (inp) 3241 inp->inp_route = sc->sc_route4; /* struct assignment */ 3242 #ifdef INET6 3243 else 3244 in6p->in6p_route = sc->sc_route6; 3245 #endif 3246 sc->sc_route4.ro_rt = NULL; 3247 3248 am = m_get(M_DONTWAIT, MT_SONAME); /* XXX */ 3249 if (am == NULL) 3250 goto resetandabort; 3251 MCLAIM(am, &tcp_mowner); 3252 am->m_len = src->sa_len; 3253 bcopy(src, mtod(am, caddr_t), src->sa_len); 3254 if (inp) { 3255 if (in_pcbconnect(inp, am)) { 3256 (void) m_free(am); 3257 goto resetandabort; 3258 } 3259 } 3260 #ifdef INET6 3261 else if (in6p) { 3262 if (src->sa_family == AF_INET) { 3263 /* IPv4 packet to AF_INET6 socket */ 3264 struct sockaddr_in6 *sin6; 3265 sin6 = mtod(am, struct sockaddr_in6 *); 3266 am->m_len = sizeof(*sin6); 3267 bzero(sin6, sizeof(*sin6)); 3268 sin6->sin6_family = AF_INET6; 3269 sin6->sin6_len = sizeof(*sin6); 3270 sin6->sin6_port = ((struct sockaddr_in *)src)->sin_port; 3271 sin6->sin6_addr.s6_addr16[5] = htons(0xffff); 3272 bcopy(&((struct sockaddr_in *)src)->sin_addr, 3273 &sin6->sin6_addr.s6_addr32[3], 3274 sizeof(sin6->sin6_addr.s6_addr32[3])); 3275 } 3276 if (in6_pcbconnect(in6p, am)) { 3277 (void) m_free(am); 3278 goto resetandabort; 3279 } 3280 } 3281 #endif 3282 else { 3283 (void) m_free(am); 3284 goto resetandabort; 3285 } 3286 (void) m_free(am); 3287 3288 if (inp) 3289 tp = intotcpcb(inp); 3290 #ifdef INET6 3291 else if (in6p) 3292 tp = in6totcpcb(in6p); 3293 #endif 3294 else 3295 tp = NULL; 3296 tp->t_flags = sototcpcb(oso)->t_flags & TF_NODELAY; 3297 if (sc->sc_request_r_scale != 15) { 3298 tp->requested_s_scale = sc->sc_requested_s_scale; 3299 tp->request_r_scale = sc->sc_request_r_scale; 3300 tp->snd_scale = sc->sc_requested_s_scale; 3301 tp->rcv_scale = sc->sc_request_r_scale; 3302 tp->t_flags |= TF_REQ_SCALE|TF_RCVD_SCALE; 3303 } 3304 if (sc->sc_flags & SCF_TIMESTAMP) 3305 tp->t_flags |= TF_REQ_TSTMP|TF_RCVD_TSTMP; 3306 tp->ts_timebase = sc->sc_timebase; 3307 3308 tp->t_template = tcp_template(tp); 3309 if (tp->t_template == 0) { 3310 tp = tcp_drop(tp, ENOBUFS); /* destroys socket */ 3311 so = NULL; 3312 m_freem(m); 3313 goto abort; 3314 } 3315 3316 tp->iss = sc->sc_iss; 3317 tp->irs = sc->sc_irs; 3318 tcp_sendseqinit(tp); 3319 tcp_rcvseqinit(tp); 3320 tp->t_state = TCPS_SYN_RECEIVED; 3321 TCP_TIMER_ARM(tp, TCPT_KEEP, TCPTV_KEEP_INIT); 3322 tcpstat.tcps_accepts++; 3323 3324 /* Initialize tp->t_ourmss before we deal with the peer's! */ 3325 tp->t_ourmss = sc->sc_ourmaxseg; 3326 tcp_mss_from_peer(tp, sc->sc_peermaxseg); 3327 3328 /* 3329 * Initialize the initial congestion window. If we 3330 * had to retransmit the SYN,ACK, we must initialize cwnd 3331 * to 1 segment (i.e. the Loss Window). 3332 */ 3333 if (sc->sc_rxtshift) 3334 tp->snd_cwnd = tp->t_peermss; 3335 else { 3336 int ss = tcp_init_win; 3337 #ifdef INET 3338 if (inp != NULL && in_localaddr(inp->inp_faddr)) 3339 ss = tcp_init_win_local; 3340 #endif 3341 #ifdef INET6 3342 if (in6p != NULL && in6_localaddr(&in6p->in6p_faddr)) 3343 ss = tcp_init_win_local; 3344 #endif 3345 tp->snd_cwnd = TCP_INITIAL_WINDOW(ss, tp->t_peermss); 3346 } 3347 3348 tcp_rmx_rtt(tp); 3349 tp->snd_wl1 = sc->sc_irs; 3350 tp->rcv_up = sc->sc_irs + 1; 3351 3352 /* 3353 * This is what whould have happened in tcp_output() when 3354 * the SYN,ACK was sent. 3355 */ 3356 tp->snd_up = tp->snd_una; 3357 tp->snd_max = tp->snd_nxt = tp->iss+1; 3358 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 3359 if (sc->sc_win > 0 && SEQ_GT(tp->rcv_nxt + sc->sc_win, tp->rcv_adv)) 3360 tp->rcv_adv = tp->rcv_nxt + sc->sc_win; 3361 tp->last_ack_sent = tp->rcv_nxt; 3362 3363 tcpstat.tcps_sc_completed++; 3364 SYN_CACHE_PUT(sc); 3365 return (so); 3366 3367 resetandabort: 3368 (void) tcp_respond(NULL, m, m, th, 3369 th->th_seq + tlen, (tcp_seq)0, TH_RST|TH_ACK); 3370 abort: 3371 if (so != NULL) 3372 (void) soabort(so); 3373 SYN_CACHE_PUT(sc); 3374 tcpstat.tcps_sc_aborted++; 3375 return ((struct socket *)(-1)); 3376 } 3377 3378 /* 3379 * This function is called when we get a RST for a 3380 * non-existent connection, so that we can see if the 3381 * connection is in the syn cache. If it is, zap it. 3382 */ 3383 3384 void 3385 syn_cache_reset(src, dst, th) 3386 struct sockaddr *src; 3387 struct sockaddr *dst; 3388 struct tcphdr *th; 3389 { 3390 struct syn_cache *sc; 3391 struct syn_cache_head *scp; 3392 int s = splsoftnet(); 3393 3394 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 3395 splx(s); 3396 return; 3397 } 3398 if (SEQ_LT(th->th_seq, sc->sc_irs) || 3399 SEQ_GT(th->th_seq, sc->sc_irs+1)) { 3400 splx(s); 3401 return; 3402 } 3403 SYN_CACHE_RM(sc); 3404 splx(s); 3405 tcpstat.tcps_sc_reset++; 3406 SYN_CACHE_PUT(sc); 3407 } 3408 3409 void 3410 syn_cache_unreach(src, dst, th) 3411 struct sockaddr *src; 3412 struct sockaddr *dst; 3413 struct tcphdr *th; 3414 { 3415 struct syn_cache *sc; 3416 struct syn_cache_head *scp; 3417 int s; 3418 3419 s = splsoftnet(); 3420 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 3421 splx(s); 3422 return; 3423 } 3424 /* If the sequence number != sc_iss, then it's a bogus ICMP msg */ 3425 if (ntohl (th->th_seq) != sc->sc_iss) { 3426 splx(s); 3427 return; 3428 } 3429 3430 /* 3431 * If we've rertransmitted 3 times and this is our second error, 3432 * we remove the entry. Otherwise, we allow it to continue on. 3433 * This prevents us from incorrectly nuking an entry during a 3434 * spurious network outage. 3435 * 3436 * See tcp_notify(). 3437 */ 3438 if ((sc->sc_flags & SCF_UNREACH) == 0 || sc->sc_rxtshift < 3) { 3439 sc->sc_flags |= SCF_UNREACH; 3440 splx(s); 3441 return; 3442 } 3443 3444 SYN_CACHE_RM(sc); 3445 splx(s); 3446 tcpstat.tcps_sc_unreach++; 3447 SYN_CACHE_PUT(sc); 3448 } 3449 3450 /* 3451 * Given a LISTEN socket and an inbound SYN request, add 3452 * this to the syn cache, and send back a segment: 3453 * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK> 3454 * to the source. 3455 * 3456 * IMPORTANT NOTE: We do _NOT_ ACK data that might accompany the SYN. 3457 * Doing so would require that we hold onto the data and deliver it 3458 * to the application. However, if we are the target of a SYN-flood 3459 * DoS attack, an attacker could send data which would eventually 3460 * consume all available buffer space if it were ACKed. By not ACKing 3461 * the data, we avoid this DoS scenario. 3462 */ 3463 3464 int 3465 syn_cache_add(src, dst, th, hlen, so, m, optp, optlen, oi) 3466 struct sockaddr *src; 3467 struct sockaddr *dst; 3468 struct tcphdr *th; 3469 unsigned int hlen; 3470 struct socket *so; 3471 struct mbuf *m; 3472 u_char *optp; 3473 int optlen; 3474 struct tcp_opt_info *oi; 3475 { 3476 struct tcpcb tb, *tp; 3477 long win; 3478 struct syn_cache *sc; 3479 struct syn_cache_head *scp; 3480 struct mbuf *ipopts; 3481 3482 tp = sototcpcb(so); 3483 3484 /* 3485 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN 3486 * 3487 * Note this check is performed in tcp_input() very early on. 3488 */ 3489 3490 /* 3491 * Initialize some local state. 3492 */ 3493 win = sbspace(&so->so_rcv); 3494 if (win > TCP_MAXWIN) 3495 win = TCP_MAXWIN; 3496 3497 switch (src->sa_family) { 3498 #ifdef INET 3499 case AF_INET: 3500 /* 3501 * Remember the IP options, if any. 3502 */ 3503 ipopts = ip_srcroute(); 3504 break; 3505 #endif 3506 default: 3507 ipopts = NULL; 3508 } 3509 3510 if (optp) { 3511 tb.t_flags = tcp_do_rfc1323 ? (TF_REQ_SCALE|TF_REQ_TSTMP) : 0; 3512 tcp_dooptions(&tb, optp, optlen, th, oi); 3513 } else 3514 tb.t_flags = 0; 3515 3516 /* 3517 * See if we already have an entry for this connection. 3518 * If we do, resend the SYN,ACK. We do not count this 3519 * as a retransmission (XXX though maybe we should). 3520 */ 3521 if ((sc = syn_cache_lookup(src, dst, &scp)) != NULL) { 3522 tcpstat.tcps_sc_dupesyn++; 3523 if (ipopts) { 3524 /* 3525 * If we were remembering a previous source route, 3526 * forget it and use the new one we've been given. 3527 */ 3528 if (sc->sc_ipopts) 3529 (void) m_free(sc->sc_ipopts); 3530 sc->sc_ipopts = ipopts; 3531 } 3532 sc->sc_timestamp = tb.ts_recent; 3533 if (syn_cache_respond(sc, m) == 0) { 3534 tcpstat.tcps_sndacks++; 3535 tcpstat.tcps_sndtotal++; 3536 } 3537 return (1); 3538 } 3539 3540 sc = pool_get(&syn_cache_pool, PR_NOWAIT); 3541 if (sc == NULL) { 3542 if (ipopts) 3543 (void) m_free(ipopts); 3544 return (0); 3545 } 3546 3547 /* 3548 * Fill in the cache, and put the necessary IP and TCP 3549 * options into the reply. 3550 */ 3551 bzero(sc, sizeof(struct syn_cache)); 3552 callout_init(&sc->sc_timer); 3553 bcopy(src, &sc->sc_src, src->sa_len); 3554 bcopy(dst, &sc->sc_dst, dst->sa_len); 3555 sc->sc_flags = 0; 3556 sc->sc_ipopts = ipopts; 3557 sc->sc_irs = th->th_seq; 3558 switch (src->sa_family) { 3559 #ifdef INET 3560 case AF_INET: 3561 { 3562 struct sockaddr_in *srcin = (void *) src; 3563 struct sockaddr_in *dstin = (void *) dst; 3564 3565 sc->sc_iss = tcp_new_iss1(&dstin->sin_addr, 3566 &srcin->sin_addr, dstin->sin_port, 3567 srcin->sin_port, sizeof(dstin->sin_addr), 0); 3568 break; 3569 } 3570 #endif /* INET */ 3571 #ifdef INET6 3572 case AF_INET6: 3573 { 3574 struct sockaddr_in6 *srcin6 = (void *) src; 3575 struct sockaddr_in6 *dstin6 = (void *) dst; 3576 3577 sc->sc_iss = tcp_new_iss1(&dstin6->sin6_addr, 3578 &srcin6->sin6_addr, dstin6->sin6_port, 3579 srcin6->sin6_port, sizeof(dstin6->sin6_addr), 0); 3580 break; 3581 } 3582 #endif /* INET6 */ 3583 } 3584 sc->sc_peermaxseg = oi->maxseg; 3585 sc->sc_ourmaxseg = tcp_mss_to_advertise(m->m_flags & M_PKTHDR ? 3586 m->m_pkthdr.rcvif : NULL, 3587 sc->sc_src.sa.sa_family); 3588 sc->sc_win = win; 3589 sc->sc_timebase = tcp_now; /* see tcp_newtcpcb() */ 3590 sc->sc_timestamp = tb.ts_recent; 3591 if ((tb.t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP)) == 3592 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) 3593 sc->sc_flags |= SCF_TIMESTAMP; 3594 if ((tb.t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 3595 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 3596 sc->sc_requested_s_scale = tb.requested_s_scale; 3597 sc->sc_request_r_scale = 0; 3598 while (sc->sc_request_r_scale < TCP_MAX_WINSHIFT && 3599 TCP_MAXWIN << sc->sc_request_r_scale < 3600 so->so_rcv.sb_hiwat) 3601 sc->sc_request_r_scale++; 3602 } else { 3603 sc->sc_requested_s_scale = 15; 3604 sc->sc_request_r_scale = 15; 3605 } 3606 sc->sc_tp = tp; 3607 if (syn_cache_respond(sc, m) == 0) { 3608 syn_cache_insert(sc, tp); 3609 tcpstat.tcps_sndacks++; 3610 tcpstat.tcps_sndtotal++; 3611 } else { 3612 SYN_CACHE_PUT(sc); 3613 tcpstat.tcps_sc_dropped++; 3614 } 3615 return (1); 3616 } 3617 3618 int 3619 syn_cache_respond(sc, m) 3620 struct syn_cache *sc; 3621 struct mbuf *m; 3622 { 3623 struct route *ro; 3624 u_int8_t *optp; 3625 int optlen, error; 3626 u_int16_t tlen; 3627 struct ip *ip = NULL; 3628 #ifdef INET6 3629 struct ip6_hdr *ip6 = NULL; 3630 #endif 3631 struct tcphdr *th; 3632 u_int hlen; 3633 3634 switch (sc->sc_src.sa.sa_family) { 3635 case AF_INET: 3636 hlen = sizeof(struct ip); 3637 ro = &sc->sc_route4; 3638 break; 3639 #ifdef INET6 3640 case AF_INET6: 3641 hlen = sizeof(struct ip6_hdr); 3642 ro = (struct route *)&sc->sc_route6; 3643 break; 3644 #endif 3645 default: 3646 if (m) 3647 m_freem(m); 3648 return EAFNOSUPPORT; 3649 } 3650 3651 /* Compute the size of the TCP options. */ 3652 optlen = 4 + (sc->sc_request_r_scale != 15 ? 4 : 0) + 3653 ((sc->sc_flags & SCF_TIMESTAMP) ? TCPOLEN_TSTAMP_APPA : 0); 3654 3655 tlen = hlen + sizeof(struct tcphdr) + optlen; 3656 3657 /* 3658 * Create the IP+TCP header from scratch. 3659 */ 3660 if (m) 3661 m_freem(m); 3662 #ifdef DIAGNOSTIC 3663 if (max_linkhdr + tlen > MCLBYTES) 3664 return (ENOBUFS); 3665 #endif 3666 MGETHDR(m, M_DONTWAIT, MT_DATA); 3667 if (m && tlen > MHLEN) { 3668 MCLGET(m, M_DONTWAIT); 3669 if ((m->m_flags & M_EXT) == 0) { 3670 m_freem(m); 3671 m = NULL; 3672 } 3673 } 3674 if (m == NULL) 3675 return (ENOBUFS); 3676 MCLAIM(m, &tcp_tx_mowner); 3677 3678 /* Fixup the mbuf. */ 3679 m->m_data += max_linkhdr; 3680 m->m_len = m->m_pkthdr.len = tlen; 3681 #ifdef IPSEC 3682 if (sc->sc_tp) { 3683 struct tcpcb *tp; 3684 struct socket *so; 3685 3686 tp = sc->sc_tp; 3687 if (tp->t_inpcb) 3688 so = tp->t_inpcb->inp_socket; 3689 #ifdef INET6 3690 else if (tp->t_in6pcb) 3691 so = tp->t_in6pcb->in6p_socket; 3692 #endif 3693 else 3694 so = NULL; 3695 /* use IPsec policy on listening socket, on SYN ACK */ 3696 if (ipsec_setsocket(m, so) != 0) { 3697 m_freem(m); 3698 return ENOBUFS; 3699 } 3700 } 3701 #endif 3702 m->m_pkthdr.rcvif = NULL; 3703 memset(mtod(m, u_char *), 0, tlen); 3704 3705 switch (sc->sc_src.sa.sa_family) { 3706 case AF_INET: 3707 ip = mtod(m, struct ip *); 3708 ip->ip_dst = sc->sc_src.sin.sin_addr; 3709 ip->ip_src = sc->sc_dst.sin.sin_addr; 3710 ip->ip_p = IPPROTO_TCP; 3711 th = (struct tcphdr *)(ip + 1); 3712 th->th_dport = sc->sc_src.sin.sin_port; 3713 th->th_sport = sc->sc_dst.sin.sin_port; 3714 break; 3715 #ifdef INET6 3716 case AF_INET6: 3717 ip6 = mtod(m, struct ip6_hdr *); 3718 ip6->ip6_dst = sc->sc_src.sin6.sin6_addr; 3719 ip6->ip6_src = sc->sc_dst.sin6.sin6_addr; 3720 ip6->ip6_nxt = IPPROTO_TCP; 3721 /* ip6_plen will be updated in ip6_output() */ 3722 th = (struct tcphdr *)(ip6 + 1); 3723 th->th_dport = sc->sc_src.sin6.sin6_port; 3724 th->th_sport = sc->sc_dst.sin6.sin6_port; 3725 break; 3726 #endif 3727 default: 3728 th = NULL; 3729 } 3730 3731 th->th_seq = htonl(sc->sc_iss); 3732 th->th_ack = htonl(sc->sc_irs + 1); 3733 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 3734 th->th_flags = TH_SYN|TH_ACK; 3735 th->th_win = htons(sc->sc_win); 3736 /* th_sum already 0 */ 3737 /* th_urp already 0 */ 3738 3739 /* Tack on the TCP options. */ 3740 optp = (u_int8_t *)(th + 1); 3741 *optp++ = TCPOPT_MAXSEG; 3742 *optp++ = 4; 3743 *optp++ = (sc->sc_ourmaxseg >> 8) & 0xff; 3744 *optp++ = sc->sc_ourmaxseg & 0xff; 3745 3746 if (sc->sc_request_r_scale != 15) { 3747 *((u_int32_t *)optp) = htonl(TCPOPT_NOP << 24 | 3748 TCPOPT_WINDOW << 16 | TCPOLEN_WINDOW << 8 | 3749 sc->sc_request_r_scale); 3750 optp += 4; 3751 } 3752 3753 if (sc->sc_flags & SCF_TIMESTAMP) { 3754 u_int32_t *lp = (u_int32_t *)(optp); 3755 /* Form timestamp option as shown in appendix A of RFC 1323. */ 3756 *lp++ = htonl(TCPOPT_TSTAMP_HDR); 3757 *lp++ = htonl(SYN_CACHE_TIMESTAMP(sc)); 3758 *lp = htonl(sc->sc_timestamp); 3759 optp += TCPOLEN_TSTAMP_APPA; 3760 } 3761 3762 /* Compute the packet's checksum. */ 3763 switch (sc->sc_src.sa.sa_family) { 3764 case AF_INET: 3765 ip->ip_len = htons(tlen - hlen); 3766 th->th_sum = 0; 3767 th->th_sum = in_cksum(m, tlen); 3768 break; 3769 #ifdef INET6 3770 case AF_INET6: 3771 ip6->ip6_plen = htons(tlen - hlen); 3772 th->th_sum = 0; 3773 th->th_sum = in6_cksum(m, IPPROTO_TCP, hlen, tlen - hlen); 3774 break; 3775 #endif 3776 } 3777 3778 /* 3779 * Fill in some straggling IP bits. Note the stack expects 3780 * ip_len to be in host order, for convenience. 3781 */ 3782 switch (sc->sc_src.sa.sa_family) { 3783 #ifdef INET 3784 case AF_INET: 3785 ip->ip_len = htons(tlen); 3786 ip->ip_ttl = ip_defttl; 3787 /* XXX tos? */ 3788 break; 3789 #endif 3790 #ifdef INET6 3791 case AF_INET6: 3792 ip6->ip6_vfc &= ~IPV6_VERSION_MASK; 3793 ip6->ip6_vfc |= IPV6_VERSION; 3794 ip6->ip6_plen = htons(tlen - hlen); 3795 /* ip6_hlim will be initialized afterwards */ 3796 /* XXX flowlabel? */ 3797 break; 3798 #endif 3799 } 3800 3801 switch (sc->sc_src.sa.sa_family) { 3802 #ifdef INET 3803 case AF_INET: 3804 error = ip_output(m, sc->sc_ipopts, ro, 3805 (ip_mtudisc ? IP_MTUDISC : 0), 3806 NULL); 3807 break; 3808 #endif 3809 #ifdef INET6 3810 case AF_INET6: 3811 ip6->ip6_hlim = in6_selecthlim(NULL, 3812 ro->ro_rt ? ro->ro_rt->rt_ifp : NULL); 3813 3814 error = ip6_output(m, NULL /*XXX*/, (struct route_in6 *)ro, 3815 0, NULL, NULL); 3816 break; 3817 #endif 3818 default: 3819 error = EAFNOSUPPORT; 3820 break; 3821 } 3822 return (error); 3823 } 3824