1 /* $NetBSD: tcp_input.c,v 1.243 2006/06/07 22:34:01 kardel Exp $ */ 2 3 /* 4 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. Neither the name of the project nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 /* 33 * @(#)COPYRIGHT 1.1 (NRL) 17 January 1995 34 * 35 * NRL grants permission for redistribution and use in source and binary 36 * forms, with or without modification, of the software and documentation 37 * created at NRL provided that the following conditions are met: 38 * 39 * 1. Redistributions of source code must retain the above copyright 40 * notice, this list of conditions and the following disclaimer. 41 * 2. Redistributions in binary form must reproduce the above copyright 42 * notice, this list of conditions and the following disclaimer in the 43 * documentation and/or other materials provided with the distribution. 44 * 3. All advertising materials mentioning features or use of this software 45 * must display the following acknowledgements: 46 * This product includes software developed by the University of 47 * California, Berkeley and its contributors. 48 * This product includes software developed at the Information 49 * Technology Division, US Naval Research Laboratory. 50 * 4. Neither the name of the NRL nor the names of its contributors 51 * may be used to endorse or promote products derived from this software 52 * without specific prior written permission. 53 * 54 * THE SOFTWARE PROVIDED BY NRL IS PROVIDED BY NRL AND CONTRIBUTORS ``AS 55 * IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 56 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A 57 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL NRL OR 58 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 59 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 60 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 61 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF 62 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 63 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 64 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 65 * 66 * The views and conclusions contained in the software and documentation 67 * are those of the authors and should not be interpreted as representing 68 * official policies, either expressed or implied, of the US Naval 69 * Research Laboratory (NRL). 70 */ 71 72 /*- 73 * Copyright (c) 1997, 1998, 1999, 2001, 2005 The NetBSD Foundation, Inc. 74 * All rights reserved. 75 * 76 * This code is derived from software contributed to The NetBSD Foundation 77 * by Jason R. Thorpe and Kevin M. Lahey of the Numerical Aerospace Simulation 78 * Facility, NASA Ames Research Center. 79 * This code is derived from software contributed to The NetBSD Foundation 80 * by Charles M. Hannum. 81 * 82 * Redistribution and use in source and binary forms, with or without 83 * modification, are permitted provided that the following conditions 84 * are met: 85 * 1. Redistributions of source code must retain the above copyright 86 * notice, this list of conditions and the following disclaimer. 87 * 2. Redistributions in binary form must reproduce the above copyright 88 * notice, this list of conditions and the following disclaimer in the 89 * documentation and/or other materials provided with the distribution. 90 * 3. All advertising materials mentioning features or use of this software 91 * must display the following acknowledgement: 92 * This product includes software developed by the NetBSD 93 * Foundation, Inc. and its contributors. 94 * 4. Neither the name of The NetBSD Foundation nor the names of its 95 * contributors may be used to endorse or promote products derived 96 * from this software without specific prior written permission. 97 * 98 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 99 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 100 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 101 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 102 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 103 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 104 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 105 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 106 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 107 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 108 * POSSIBILITY OF SUCH DAMAGE. 109 */ 110 111 /* 112 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995 113 * The Regents of the University of California. All rights reserved. 114 * 115 * Redistribution and use in source and binary forms, with or without 116 * modification, are permitted provided that the following conditions 117 * are met: 118 * 1. Redistributions of source code must retain the above copyright 119 * notice, this list of conditions and the following disclaimer. 120 * 2. Redistributions in binary form must reproduce the above copyright 121 * notice, this list of conditions and the following disclaimer in the 122 * documentation and/or other materials provided with the distribution. 123 * 3. Neither the name of the University nor the names of its contributors 124 * may be used to endorse or promote products derived from this software 125 * without specific prior written permission. 126 * 127 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 128 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 129 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 130 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 131 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 132 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 133 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 134 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 135 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 136 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 137 * SUCH DAMAGE. 138 * 139 * @(#)tcp_input.c 8.12 (Berkeley) 5/24/95 140 */ 141 142 /* 143 * TODO list for SYN cache stuff: 144 * 145 * Find room for a "state" field, which is needed to keep a 146 * compressed state for TIME_WAIT TCBs. It's been noted already 147 * that this is fairly important for very high-volume web and 148 * mail servers, which use a large number of short-lived 149 * connections. 150 */ 151 152 #include <sys/cdefs.h> 153 __KERNEL_RCSID(0, "$NetBSD: tcp_input.c,v 1.243 2006/06/07 22:34:01 kardel Exp $"); 154 155 #include "opt_inet.h" 156 #include "opt_ipsec.h" 157 #include "opt_inet_csum.h" 158 #include "opt_tcp_debug.h" 159 160 #include <sys/param.h> 161 #include <sys/systm.h> 162 #include <sys/malloc.h> 163 #include <sys/mbuf.h> 164 #include <sys/protosw.h> 165 #include <sys/socket.h> 166 #include <sys/socketvar.h> 167 #include <sys/errno.h> 168 #include <sys/syslog.h> 169 #include <sys/pool.h> 170 #include <sys/domain.h> 171 #include <sys/kernel.h> 172 #ifdef TCP_SIGNATURE 173 #include <sys/md5.h> 174 #endif 175 176 #include <net/if.h> 177 #include <net/route.h> 178 #include <net/if_types.h> 179 180 #include <netinet/in.h> 181 #include <netinet/in_systm.h> 182 #include <netinet/ip.h> 183 #include <netinet/in_pcb.h> 184 #include <netinet/in_var.h> 185 #include <netinet/ip_var.h> 186 #include <netinet/in_offload.h> 187 188 #ifdef INET6 189 #ifndef INET 190 #include <netinet/in.h> 191 #endif 192 #include <netinet/ip6.h> 193 #include <netinet6/ip6_var.h> 194 #include <netinet6/in6_pcb.h> 195 #include <netinet6/ip6_var.h> 196 #include <netinet6/in6_var.h> 197 #include <netinet/icmp6.h> 198 #include <netinet6/nd6.h> 199 #ifdef TCP_SIGNATURE 200 #include <netinet6/scope6_var.h> 201 #endif 202 #endif 203 204 #ifndef INET6 205 /* always need ip6.h for IP6_EXTHDR_GET */ 206 #include <netinet/ip6.h> 207 #endif 208 209 #include <netinet/tcp.h> 210 #include <netinet/tcp_fsm.h> 211 #include <netinet/tcp_seq.h> 212 #include <netinet/tcp_timer.h> 213 #include <netinet/tcp_var.h> 214 #include <netinet/tcpip.h> 215 #include <netinet/tcp_debug.h> 216 217 #include <machine/stdarg.h> 218 219 #ifdef IPSEC 220 #include <netinet6/ipsec.h> 221 #include <netkey/key.h> 222 #endif /*IPSEC*/ 223 #ifdef INET6 224 #include "faith.h" 225 #if defined(NFAITH) && NFAITH > 0 226 #include <net/if_faith.h> 227 #endif 228 #endif /* IPSEC */ 229 230 #ifdef FAST_IPSEC 231 #include <netipsec/ipsec.h> 232 #include <netipsec/ipsec_var.h> /* XXX ipsecstat namespace */ 233 #include <netipsec/key.h> 234 #ifdef INET6 235 #include <netipsec/ipsec6.h> 236 #endif 237 #endif /* FAST_IPSEC*/ 238 239 int tcprexmtthresh = 3; 240 int tcp_log_refused; 241 242 static int tcp_rst_ppslim_count = 0; 243 static struct timeval tcp_rst_ppslim_last; 244 static int tcp_ackdrop_ppslim_count = 0; 245 static struct timeval tcp_ackdrop_ppslim_last; 246 247 #define TCP_PAWS_IDLE (24U * 24 * 60 * 60 * PR_SLOWHZ) 248 249 /* for modulo comparisons of timestamps */ 250 #define TSTMP_LT(a,b) ((int)((a)-(b)) < 0) 251 #define TSTMP_GEQ(a,b) ((int)((a)-(b)) >= 0) 252 253 /* 254 * Neighbor Discovery, Neighbor Unreachability Detection Upper layer hint. 255 */ 256 #ifdef INET6 257 #define ND6_HINT(tp) \ 258 do { \ 259 if (tp && tp->t_in6pcb && tp->t_family == AF_INET6 && \ 260 tp->t_in6pcb->in6p_route.ro_rt) { \ 261 nd6_nud_hint(tp->t_in6pcb->in6p_route.ro_rt, NULL, 0); \ 262 } \ 263 } while (/*CONSTCOND*/ 0) 264 #else 265 #define ND6_HINT(tp) 266 #endif 267 268 /* 269 * Macro to compute ACK transmission behavior. Delay the ACK unless 270 * we have already delayed an ACK (must send an ACK every two segments). 271 * We also ACK immediately if we received a PUSH and the ACK-on-PUSH 272 * option is enabled. 273 */ 274 #define TCP_SETUP_ACK(tp, th) \ 275 do { \ 276 if ((tp)->t_flags & TF_DELACK || \ 277 (tcp_ack_on_push && (th)->th_flags & TH_PUSH)) \ 278 tp->t_flags |= TF_ACKNOW; \ 279 else \ 280 TCP_SET_DELACK(tp); \ 281 } while (/*CONSTCOND*/ 0) 282 283 #define ICMP_CHECK(tp, th, acked) \ 284 do { \ 285 /* \ 286 * If we had a pending ICMP message that \ 287 * refers to data that have just been \ 288 * acknowledged, disregard the recorded ICMP \ 289 * message. \ 290 */ \ 291 if (((tp)->t_flags & TF_PMTUD_PEND) && \ 292 SEQ_GT((th)->th_ack, (tp)->t_pmtud_th_seq)) \ 293 (tp)->t_flags &= ~TF_PMTUD_PEND; \ 294 \ 295 /* \ 296 * Keep track of the largest chunk of data \ 297 * acknowledged since last PMTU update \ 298 */ \ 299 if ((tp)->t_pmtud_mss_acked < (acked)) \ 300 (tp)->t_pmtud_mss_acked = (acked); \ 301 } while (/*CONSTCOND*/ 0) 302 303 /* 304 * Convert TCP protocol fields to host order for easier processing. 305 */ 306 #define TCP_FIELDS_TO_HOST(th) \ 307 do { \ 308 NTOHL((th)->th_seq); \ 309 NTOHL((th)->th_ack); \ 310 NTOHS((th)->th_win); \ 311 NTOHS((th)->th_urp); \ 312 } while (/*CONSTCOND*/ 0) 313 314 /* 315 * ... and reverse the above. 316 */ 317 #define TCP_FIELDS_TO_NET(th) \ 318 do { \ 319 HTONL((th)->th_seq); \ 320 HTONL((th)->th_ack); \ 321 HTONS((th)->th_win); \ 322 HTONS((th)->th_urp); \ 323 } while (/*CONSTCOND*/ 0) 324 325 #ifdef TCP_CSUM_COUNTERS 326 #include <sys/device.h> 327 328 #if defined(INET) 329 extern struct evcnt tcp_hwcsum_ok; 330 extern struct evcnt tcp_hwcsum_bad; 331 extern struct evcnt tcp_hwcsum_data; 332 extern struct evcnt tcp_swcsum; 333 #endif /* defined(INET) */ 334 #if defined(INET6) 335 extern struct evcnt tcp6_hwcsum_ok; 336 extern struct evcnt tcp6_hwcsum_bad; 337 extern struct evcnt tcp6_hwcsum_data; 338 extern struct evcnt tcp6_swcsum; 339 #endif /* defined(INET6) */ 340 341 #define TCP_CSUM_COUNTER_INCR(ev) (ev)->ev_count++ 342 343 #else 344 345 #define TCP_CSUM_COUNTER_INCR(ev) /* nothing */ 346 347 #endif /* TCP_CSUM_COUNTERS */ 348 349 #ifdef TCP_REASS_COUNTERS 350 #include <sys/device.h> 351 352 extern struct evcnt tcp_reass_; 353 extern struct evcnt tcp_reass_empty; 354 extern struct evcnt tcp_reass_iteration[8]; 355 extern struct evcnt tcp_reass_prependfirst; 356 extern struct evcnt tcp_reass_prepend; 357 extern struct evcnt tcp_reass_insert; 358 extern struct evcnt tcp_reass_inserttail; 359 extern struct evcnt tcp_reass_append; 360 extern struct evcnt tcp_reass_appendtail; 361 extern struct evcnt tcp_reass_overlaptail; 362 extern struct evcnt tcp_reass_overlapfront; 363 extern struct evcnt tcp_reass_segdup; 364 extern struct evcnt tcp_reass_fragdup; 365 366 #define TCP_REASS_COUNTER_INCR(ev) (ev)->ev_count++ 367 368 #else 369 370 #define TCP_REASS_COUNTER_INCR(ev) /* nothing */ 371 372 #endif /* TCP_REASS_COUNTERS */ 373 374 #ifdef INET 375 static void tcp4_log_refused(const struct ip *, const struct tcphdr *); 376 #endif 377 #ifdef INET6 378 static void tcp6_log_refused(const struct ip6_hdr *, const struct tcphdr *); 379 #endif 380 381 #define TRAVERSE(x) while ((x)->m_next) (x) = (x)->m_next 382 383 POOL_INIT(tcpipqent_pool, sizeof(struct ipqent), 0, 0, 0, "tcpipqepl", NULL); 384 385 struct ipqent * 386 tcpipqent_alloc() 387 { 388 struct ipqent *ipqe; 389 int s; 390 391 s = splvm(); 392 ipqe = pool_get(&tcpipqent_pool, PR_NOWAIT); 393 splx(s); 394 395 return ipqe; 396 } 397 398 void 399 tcpipqent_free(struct ipqent *ipqe) 400 { 401 int s; 402 403 s = splvm(); 404 pool_put(&tcpipqent_pool, ipqe); 405 splx(s); 406 } 407 408 int 409 tcp_reass(struct tcpcb *tp, struct tcphdr *th, struct mbuf *m, int *tlen) 410 { 411 struct ipqent *p, *q, *nq, *tiqe = NULL; 412 struct socket *so = NULL; 413 int pkt_flags; 414 tcp_seq pkt_seq; 415 unsigned pkt_len; 416 u_long rcvpartdupbyte = 0; 417 u_long rcvoobyte; 418 #ifdef TCP_REASS_COUNTERS 419 u_int count = 0; 420 #endif 421 422 if (tp->t_inpcb) 423 so = tp->t_inpcb->inp_socket; 424 #ifdef INET6 425 else if (tp->t_in6pcb) 426 so = tp->t_in6pcb->in6p_socket; 427 #endif 428 429 TCP_REASS_LOCK_CHECK(tp); 430 431 /* 432 * Call with th==0 after become established to 433 * force pre-ESTABLISHED data up to user socket. 434 */ 435 if (th == 0) 436 goto present; 437 438 rcvoobyte = *tlen; 439 /* 440 * Copy these to local variables because the tcpiphdr 441 * gets munged while we are collapsing mbufs. 442 */ 443 pkt_seq = th->th_seq; 444 pkt_len = *tlen; 445 pkt_flags = th->th_flags; 446 447 TCP_REASS_COUNTER_INCR(&tcp_reass_); 448 449 if ((p = TAILQ_LAST(&tp->segq, ipqehead)) != NULL) { 450 /* 451 * When we miss a packet, the vast majority of time we get 452 * packets that follow it in order. So optimize for that. 453 */ 454 if (pkt_seq == p->ipqe_seq + p->ipqe_len) { 455 p->ipqe_len += pkt_len; 456 p->ipqe_flags |= pkt_flags; 457 m_cat(p->ipre_mlast, m); 458 TRAVERSE(p->ipre_mlast); 459 m = NULL; 460 tiqe = p; 461 TAILQ_REMOVE(&tp->timeq, p, ipqe_timeq); 462 TCP_REASS_COUNTER_INCR(&tcp_reass_appendtail); 463 goto skip_replacement; 464 } 465 /* 466 * While we're here, if the pkt is completely beyond 467 * anything we have, just insert it at the tail. 468 */ 469 if (SEQ_GT(pkt_seq, p->ipqe_seq + p->ipqe_len)) { 470 TCP_REASS_COUNTER_INCR(&tcp_reass_inserttail); 471 goto insert_it; 472 } 473 } 474 475 q = TAILQ_FIRST(&tp->segq); 476 477 if (q != NULL) { 478 /* 479 * If this segment immediately precedes the first out-of-order 480 * block, simply slap the segment in front of it and (mostly) 481 * skip the complicated logic. 482 */ 483 if (pkt_seq + pkt_len == q->ipqe_seq) { 484 q->ipqe_seq = pkt_seq; 485 q->ipqe_len += pkt_len; 486 q->ipqe_flags |= pkt_flags; 487 m_cat(m, q->ipqe_m); 488 q->ipqe_m = m; 489 q->ipre_mlast = m; /* last mbuf may have changed */ 490 TRAVERSE(q->ipre_mlast); 491 tiqe = q; 492 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 493 TCP_REASS_COUNTER_INCR(&tcp_reass_prependfirst); 494 goto skip_replacement; 495 } 496 } else { 497 TCP_REASS_COUNTER_INCR(&tcp_reass_empty); 498 } 499 500 /* 501 * Find a segment which begins after this one does. 502 */ 503 for (p = NULL; q != NULL; q = nq) { 504 nq = TAILQ_NEXT(q, ipqe_q); 505 #ifdef TCP_REASS_COUNTERS 506 count++; 507 #endif 508 /* 509 * If the received segment is just right after this 510 * fragment, merge the two together and then check 511 * for further overlaps. 512 */ 513 if (q->ipqe_seq + q->ipqe_len == pkt_seq) { 514 #ifdef TCPREASS_DEBUG 515 printf("tcp_reass[%p]: concat %u:%u(%u) to %u:%u(%u)\n", 516 tp, pkt_seq, pkt_seq + pkt_len, pkt_len, 517 q->ipqe_seq, q->ipqe_seq + q->ipqe_len, q->ipqe_len); 518 #endif 519 pkt_len += q->ipqe_len; 520 pkt_flags |= q->ipqe_flags; 521 pkt_seq = q->ipqe_seq; 522 m_cat(q->ipre_mlast, m); 523 TRAVERSE(q->ipre_mlast); 524 m = q->ipqe_m; 525 TCP_REASS_COUNTER_INCR(&tcp_reass_append); 526 goto free_ipqe; 527 } 528 /* 529 * If the received segment is completely past this 530 * fragment, we need to go the next fragment. 531 */ 532 if (SEQ_LT(q->ipqe_seq + q->ipqe_len, pkt_seq)) { 533 p = q; 534 continue; 535 } 536 /* 537 * If the fragment is past the received segment, 538 * it (or any following) can't be concatenated. 539 */ 540 if (SEQ_GT(q->ipqe_seq, pkt_seq + pkt_len)) { 541 TCP_REASS_COUNTER_INCR(&tcp_reass_insert); 542 break; 543 } 544 545 /* 546 * We've received all the data in this segment before. 547 * mark it as a duplicate and return. 548 */ 549 if (SEQ_LEQ(q->ipqe_seq, pkt_seq) && 550 SEQ_GEQ(q->ipqe_seq + q->ipqe_len, pkt_seq + pkt_len)) { 551 tcpstat.tcps_rcvduppack++; 552 tcpstat.tcps_rcvdupbyte += pkt_len; 553 tcp_new_dsack(tp, pkt_seq, pkt_len); 554 m_freem(m); 555 if (tiqe != NULL) { 556 tcpipqent_free(tiqe); 557 } 558 TCP_REASS_COUNTER_INCR(&tcp_reass_segdup); 559 return (0); 560 } 561 /* 562 * Received segment completely overlaps this fragment 563 * so we drop the fragment (this keeps the temporal 564 * ordering of segments correct). 565 */ 566 if (SEQ_GEQ(q->ipqe_seq, pkt_seq) && 567 SEQ_LEQ(q->ipqe_seq + q->ipqe_len, pkt_seq + pkt_len)) { 568 rcvpartdupbyte += q->ipqe_len; 569 m_freem(q->ipqe_m); 570 TCP_REASS_COUNTER_INCR(&tcp_reass_fragdup); 571 goto free_ipqe; 572 } 573 /* 574 * RX'ed segment extends past the end of the 575 * fragment. Drop the overlapping bytes. Then 576 * merge the fragment and segment then treat as 577 * a longer received packet. 578 */ 579 if (SEQ_LT(q->ipqe_seq, pkt_seq) && 580 SEQ_GT(q->ipqe_seq + q->ipqe_len, pkt_seq)) { 581 int overlap = q->ipqe_seq + q->ipqe_len - pkt_seq; 582 #ifdef TCPREASS_DEBUG 583 printf("tcp_reass[%p]: trim starting %d bytes of %u:%u(%u)\n", 584 tp, overlap, 585 pkt_seq, pkt_seq + pkt_len, pkt_len); 586 #endif 587 m_adj(m, overlap); 588 rcvpartdupbyte += overlap; 589 m_cat(q->ipre_mlast, m); 590 TRAVERSE(q->ipre_mlast); 591 m = q->ipqe_m; 592 pkt_seq = q->ipqe_seq; 593 pkt_len += q->ipqe_len - overlap; 594 rcvoobyte -= overlap; 595 TCP_REASS_COUNTER_INCR(&tcp_reass_overlaptail); 596 goto free_ipqe; 597 } 598 /* 599 * RX'ed segment extends past the front of the 600 * fragment. Drop the overlapping bytes on the 601 * received packet. The packet will then be 602 * contatentated with this fragment a bit later. 603 */ 604 if (SEQ_GT(q->ipqe_seq, pkt_seq) && 605 SEQ_LT(q->ipqe_seq, pkt_seq + pkt_len)) { 606 int overlap = pkt_seq + pkt_len - q->ipqe_seq; 607 #ifdef TCPREASS_DEBUG 608 printf("tcp_reass[%p]: trim trailing %d bytes of %u:%u(%u)\n", 609 tp, overlap, 610 pkt_seq, pkt_seq + pkt_len, pkt_len); 611 #endif 612 m_adj(m, -overlap); 613 pkt_len -= overlap; 614 rcvpartdupbyte += overlap; 615 TCP_REASS_COUNTER_INCR(&tcp_reass_overlapfront); 616 rcvoobyte -= overlap; 617 } 618 /* 619 * If the received segment immediates precedes this 620 * fragment then tack the fragment onto this segment 621 * and reinsert the data. 622 */ 623 if (q->ipqe_seq == pkt_seq + pkt_len) { 624 #ifdef TCPREASS_DEBUG 625 printf("tcp_reass[%p]: append %u:%u(%u) to %u:%u(%u)\n", 626 tp, q->ipqe_seq, q->ipqe_seq + q->ipqe_len, q->ipqe_len, 627 pkt_seq, pkt_seq + pkt_len, pkt_len); 628 #endif 629 pkt_len += q->ipqe_len; 630 pkt_flags |= q->ipqe_flags; 631 m_cat(m, q->ipqe_m); 632 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 633 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 634 tp->t_segqlen--; 635 KASSERT(tp->t_segqlen >= 0); 636 KASSERT(tp->t_segqlen != 0 || 637 (TAILQ_EMPTY(&tp->segq) && 638 TAILQ_EMPTY(&tp->timeq))); 639 if (tiqe == NULL) { 640 tiqe = q; 641 } else { 642 tcpipqent_free(q); 643 } 644 TCP_REASS_COUNTER_INCR(&tcp_reass_prepend); 645 break; 646 } 647 /* 648 * If the fragment is before the segment, remember it. 649 * When this loop is terminated, p will contain the 650 * pointer to fragment that is right before the received 651 * segment. 652 */ 653 if (SEQ_LEQ(q->ipqe_seq, pkt_seq)) 654 p = q; 655 656 continue; 657 658 /* 659 * This is a common operation. It also will allow 660 * to save doing a malloc/free in most instances. 661 */ 662 free_ipqe: 663 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 664 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 665 tp->t_segqlen--; 666 KASSERT(tp->t_segqlen >= 0); 667 KASSERT(tp->t_segqlen != 0 || 668 (TAILQ_EMPTY(&tp->segq) && TAILQ_EMPTY(&tp->timeq))); 669 if (tiqe == NULL) { 670 tiqe = q; 671 } else { 672 tcpipqent_free(q); 673 } 674 } 675 676 #ifdef TCP_REASS_COUNTERS 677 if (count > 7) 678 TCP_REASS_COUNTER_INCR(&tcp_reass_iteration[0]); 679 else if (count > 0) 680 TCP_REASS_COUNTER_INCR(&tcp_reass_iteration[count]); 681 #endif 682 683 insert_it: 684 685 /* 686 * Allocate a new queue entry since the received segment did not 687 * collapse onto any other out-of-order block; thus we are allocating 688 * a new block. If it had collapsed, tiqe would not be NULL and 689 * we would be reusing it. 690 * XXX If we can't, just drop the packet. XXX 691 */ 692 if (tiqe == NULL) { 693 tiqe = tcpipqent_alloc(); 694 if (tiqe == NULL) { 695 tcpstat.tcps_rcvmemdrop++; 696 m_freem(m); 697 return (0); 698 } 699 } 700 701 /* 702 * Update the counters. 703 */ 704 tcpstat.tcps_rcvoopack++; 705 tcpstat.tcps_rcvoobyte += rcvoobyte; 706 if (rcvpartdupbyte) { 707 tcpstat.tcps_rcvpartduppack++; 708 tcpstat.tcps_rcvpartdupbyte += rcvpartdupbyte; 709 } 710 711 /* 712 * Insert the new fragment queue entry into both queues. 713 */ 714 tiqe->ipqe_m = m; 715 tiqe->ipre_mlast = m; 716 tiqe->ipqe_seq = pkt_seq; 717 tiqe->ipqe_len = pkt_len; 718 tiqe->ipqe_flags = pkt_flags; 719 if (p == NULL) { 720 TAILQ_INSERT_HEAD(&tp->segq, tiqe, ipqe_q); 721 #ifdef TCPREASS_DEBUG 722 if (tiqe->ipqe_seq != tp->rcv_nxt) 723 printf("tcp_reass[%p]: insert %u:%u(%u) at front\n", 724 tp, pkt_seq, pkt_seq + pkt_len, pkt_len); 725 #endif 726 } else { 727 TAILQ_INSERT_AFTER(&tp->segq, p, tiqe, ipqe_q); 728 #ifdef TCPREASS_DEBUG 729 printf("tcp_reass[%p]: insert %u:%u(%u) after %u:%u(%u)\n", 730 tp, pkt_seq, pkt_seq + pkt_len, pkt_len, 731 p->ipqe_seq, p->ipqe_seq + p->ipqe_len, p->ipqe_len); 732 #endif 733 } 734 tp->t_segqlen++; 735 736 skip_replacement: 737 738 TAILQ_INSERT_HEAD(&tp->timeq, tiqe, ipqe_timeq); 739 740 present: 741 /* 742 * Present data to user, advancing rcv_nxt through 743 * completed sequence space. 744 */ 745 if (TCPS_HAVEESTABLISHED(tp->t_state) == 0) 746 return (0); 747 q = TAILQ_FIRST(&tp->segq); 748 if (q == NULL || q->ipqe_seq != tp->rcv_nxt) 749 return (0); 750 if (tp->t_state == TCPS_SYN_RECEIVED && q->ipqe_len) 751 return (0); 752 753 tp->rcv_nxt += q->ipqe_len; 754 pkt_flags = q->ipqe_flags & TH_FIN; 755 ND6_HINT(tp); 756 757 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 758 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 759 tp->t_segqlen--; 760 KASSERT(tp->t_segqlen >= 0); 761 KASSERT(tp->t_segqlen != 0 || 762 (TAILQ_EMPTY(&tp->segq) && TAILQ_EMPTY(&tp->timeq))); 763 if (so->so_state & SS_CANTRCVMORE) 764 m_freem(q->ipqe_m); 765 else 766 sbappendstream(&so->so_rcv, q->ipqe_m); 767 tcpipqent_free(q); 768 sorwakeup(so); 769 return (pkt_flags); 770 } 771 772 #ifdef INET6 773 int 774 tcp6_input(struct mbuf **mp, int *offp, int proto) 775 { 776 struct mbuf *m = *mp; 777 778 /* 779 * draft-itojun-ipv6-tcp-to-anycast 780 * better place to put this in? 781 */ 782 if (m->m_flags & M_ANYCAST6) { 783 struct ip6_hdr *ip6; 784 if (m->m_len < sizeof(struct ip6_hdr)) { 785 if ((m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) { 786 tcpstat.tcps_rcvshort++; 787 return IPPROTO_DONE; 788 } 789 } 790 ip6 = mtod(m, struct ip6_hdr *); 791 icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR, 792 (caddr_t)&ip6->ip6_dst - (caddr_t)ip6); 793 return IPPROTO_DONE; 794 } 795 796 tcp_input(m, *offp, proto); 797 return IPPROTO_DONE; 798 } 799 #endif 800 801 #ifdef INET 802 static void 803 tcp4_log_refused(const struct ip *ip, const struct tcphdr *th) 804 { 805 char src[4*sizeof "123"]; 806 char dst[4*sizeof "123"]; 807 808 if (ip) { 809 strlcpy(src, inet_ntoa(ip->ip_src), sizeof(src)); 810 strlcpy(dst, inet_ntoa(ip->ip_dst), sizeof(dst)); 811 } 812 else { 813 strlcpy(src, "(unknown)", sizeof(src)); 814 strlcpy(dst, "(unknown)", sizeof(dst)); 815 } 816 log(LOG_INFO, 817 "Connection attempt to TCP %s:%d from %s:%d\n", 818 dst, ntohs(th->th_dport), 819 src, ntohs(th->th_sport)); 820 } 821 #endif 822 823 #ifdef INET6 824 static void 825 tcp6_log_refused(const struct ip6_hdr *ip6, const struct tcphdr *th) 826 { 827 char src[INET6_ADDRSTRLEN]; 828 char dst[INET6_ADDRSTRLEN]; 829 830 if (ip6) { 831 strlcpy(src, ip6_sprintf(&ip6->ip6_src), sizeof(src)); 832 strlcpy(dst, ip6_sprintf(&ip6->ip6_dst), sizeof(dst)); 833 } 834 else { 835 strlcpy(src, "(unknown v6)", sizeof(src)); 836 strlcpy(dst, "(unknown v6)", sizeof(dst)); 837 } 838 log(LOG_INFO, 839 "Connection attempt to TCP [%s]:%d from [%s]:%d\n", 840 dst, ntohs(th->th_dport), 841 src, ntohs(th->th_sport)); 842 } 843 #endif 844 845 /* 846 * Checksum extended TCP header and data. 847 */ 848 int 849 tcp_input_checksum(int af, struct mbuf *m, const struct tcphdr *th, int toff, 850 int off, int tlen) 851 { 852 853 /* 854 * XXX it's better to record and check if this mbuf is 855 * already checked. 856 */ 857 858 switch (af) { 859 #ifdef INET 860 case AF_INET: 861 switch (m->m_pkthdr.csum_flags & 862 ((m->m_pkthdr.rcvif->if_csum_flags_rx & M_CSUM_TCPv4) | 863 M_CSUM_TCP_UDP_BAD | M_CSUM_DATA)) { 864 case M_CSUM_TCPv4|M_CSUM_TCP_UDP_BAD: 865 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_bad); 866 goto badcsum; 867 868 case M_CSUM_TCPv4|M_CSUM_DATA: { 869 u_int32_t hw_csum = m->m_pkthdr.csum_data; 870 871 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_data); 872 if (m->m_pkthdr.csum_flags & M_CSUM_NO_PSEUDOHDR) { 873 const struct ip *ip = 874 mtod(m, const struct ip *); 875 876 hw_csum = in_cksum_phdr(ip->ip_src.s_addr, 877 ip->ip_dst.s_addr, 878 htons(hw_csum + tlen + off + IPPROTO_TCP)); 879 } 880 if ((hw_csum ^ 0xffff) != 0) 881 goto badcsum; 882 break; 883 } 884 885 case M_CSUM_TCPv4: 886 /* Checksum was okay. */ 887 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_ok); 888 break; 889 890 default: 891 /* 892 * Must compute it ourselves. Maybe skip checksum 893 * on loopback interfaces. 894 */ 895 if (__predict_true(!(m->m_pkthdr.rcvif->if_flags & 896 IFF_LOOPBACK) || 897 tcp_do_loopback_cksum)) { 898 TCP_CSUM_COUNTER_INCR(&tcp_swcsum); 899 if (in4_cksum(m, IPPROTO_TCP, toff, 900 tlen + off) != 0) 901 goto badcsum; 902 } 903 break; 904 } 905 break; 906 #endif /* INET4 */ 907 908 #ifdef INET6 909 case AF_INET6: 910 switch (m->m_pkthdr.csum_flags & 911 ((m->m_pkthdr.rcvif->if_csum_flags_rx & M_CSUM_TCPv6) | 912 M_CSUM_TCP_UDP_BAD | M_CSUM_DATA)) { 913 case M_CSUM_TCPv6|M_CSUM_TCP_UDP_BAD: 914 TCP_CSUM_COUNTER_INCR(&tcp6_hwcsum_bad); 915 goto badcsum; 916 917 #if 0 /* notyet */ 918 case M_CSUM_TCPv6|M_CSUM_DATA: 919 #endif 920 921 case M_CSUM_TCPv6: 922 /* Checksum was okay. */ 923 TCP_CSUM_COUNTER_INCR(&tcp6_hwcsum_ok); 924 break; 925 926 default: 927 /* 928 * Must compute it ourselves. Maybe skip checksum 929 * on loopback interfaces. 930 */ 931 if (__predict_true((m->m_flags & M_LOOP) == 0 || 932 tcp_do_loopback_cksum)) { 933 TCP_CSUM_COUNTER_INCR(&tcp6_swcsum); 934 if (in6_cksum(m, IPPROTO_TCP, toff, 935 tlen + off) != 0) 936 goto badcsum; 937 } 938 } 939 break; 940 #endif /* INET6 */ 941 } 942 943 return 0; 944 945 badcsum: 946 tcpstat.tcps_rcvbadsum++; 947 return -1; 948 } 949 950 /* 951 * TCP input routine, follows pages 65-76 of RFC 793 very closely. 952 */ 953 void 954 tcp_input(struct mbuf *m, ...) 955 { 956 struct tcphdr *th; 957 struct ip *ip; 958 struct inpcb *inp; 959 #ifdef INET6 960 struct ip6_hdr *ip6; 961 struct in6pcb *in6p; 962 #endif 963 u_int8_t *optp = NULL; 964 int optlen = 0; 965 int len, tlen, toff, hdroptlen = 0; 966 struct tcpcb *tp = 0; 967 int tiflags; 968 struct socket *so = NULL; 969 int todrop, dupseg, acked, ourfinisacked, needoutput = 0; 970 #ifdef TCP_DEBUG 971 short ostate = 0; 972 #endif 973 u_long tiwin; 974 struct tcp_opt_info opti; 975 int off, iphlen; 976 va_list ap; 977 int af; /* af on the wire */ 978 struct mbuf *tcp_saveti = NULL; 979 uint32_t ts_rtt; 980 981 MCLAIM(m, &tcp_rx_mowner); 982 va_start(ap, m); 983 toff = va_arg(ap, int); 984 (void)va_arg(ap, int); /* ignore value, advance ap */ 985 va_end(ap); 986 987 tcpstat.tcps_rcvtotal++; 988 989 bzero(&opti, sizeof(opti)); 990 opti.ts_present = 0; 991 opti.maxseg = 0; 992 993 /* 994 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN. 995 * 996 * TCP is, by definition, unicast, so we reject all 997 * multicast outright. 998 * 999 * Note, there are additional src/dst address checks in 1000 * the AF-specific code below. 1001 */ 1002 if (m->m_flags & (M_BCAST|M_MCAST)) { 1003 /* XXX stat */ 1004 goto drop; 1005 } 1006 #ifdef INET6 1007 if (m->m_flags & M_ANYCAST6) { 1008 /* XXX stat */ 1009 goto drop; 1010 } 1011 #endif 1012 1013 /* 1014 * Get IP and TCP header. 1015 * Note: IP leaves IP header in first mbuf. 1016 */ 1017 ip = mtod(m, struct ip *); 1018 #ifdef INET6 1019 ip6 = NULL; 1020 #endif 1021 switch (ip->ip_v) { 1022 #ifdef INET 1023 case 4: 1024 af = AF_INET; 1025 iphlen = sizeof(struct ip); 1026 ip = mtod(m, struct ip *); 1027 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, 1028 sizeof(struct tcphdr)); 1029 if (th == NULL) { 1030 tcpstat.tcps_rcvshort++; 1031 return; 1032 } 1033 /* We do the checksum after PCB lookup... */ 1034 len = ntohs(ip->ip_len); 1035 tlen = len - toff; 1036 break; 1037 #endif 1038 #ifdef INET6 1039 case 6: 1040 ip = NULL; 1041 iphlen = sizeof(struct ip6_hdr); 1042 af = AF_INET6; 1043 ip6 = mtod(m, struct ip6_hdr *); 1044 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, 1045 sizeof(struct tcphdr)); 1046 if (th == NULL) { 1047 tcpstat.tcps_rcvshort++; 1048 return; 1049 } 1050 1051 /* Be proactive about malicious use of IPv4 mapped address */ 1052 if (IN6_IS_ADDR_V4MAPPED(&ip6->ip6_src) || 1053 IN6_IS_ADDR_V4MAPPED(&ip6->ip6_dst)) { 1054 /* XXX stat */ 1055 goto drop; 1056 } 1057 1058 /* 1059 * Be proactive about unspecified IPv6 address in source. 1060 * As we use all-zero to indicate unbounded/unconnected pcb, 1061 * unspecified IPv6 address can be used to confuse us. 1062 * 1063 * Note that packets with unspecified IPv6 destination is 1064 * already dropped in ip6_input. 1065 */ 1066 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 1067 /* XXX stat */ 1068 goto drop; 1069 } 1070 1071 /* 1072 * Make sure destination address is not multicast. 1073 * Source address checked in ip6_input(). 1074 */ 1075 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) { 1076 /* XXX stat */ 1077 goto drop; 1078 } 1079 1080 /* We do the checksum after PCB lookup... */ 1081 len = m->m_pkthdr.len; 1082 tlen = len - toff; 1083 break; 1084 #endif 1085 default: 1086 m_freem(m); 1087 return; 1088 } 1089 1090 KASSERT(TCP_HDR_ALIGNED_P(th)); 1091 1092 /* 1093 * Check that TCP offset makes sense, 1094 * pull out TCP options and adjust length. XXX 1095 */ 1096 off = th->th_off << 2; 1097 if (off < sizeof (struct tcphdr) || off > tlen) { 1098 tcpstat.tcps_rcvbadoff++; 1099 goto drop; 1100 } 1101 tlen -= off; 1102 1103 /* 1104 * tcp_input() has been modified to use tlen to mean the TCP data 1105 * length throughout the function. Other functions can use 1106 * m->m_pkthdr.len as the basis for calculating the TCP data length. 1107 * rja 1108 */ 1109 1110 if (off > sizeof (struct tcphdr)) { 1111 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, off); 1112 if (th == NULL) { 1113 tcpstat.tcps_rcvshort++; 1114 return; 1115 } 1116 /* 1117 * NOTE: ip/ip6 will not be affected by m_pulldown() 1118 * (as they're before toff) and we don't need to update those. 1119 */ 1120 KASSERT(TCP_HDR_ALIGNED_P(th)); 1121 optlen = off - sizeof (struct tcphdr); 1122 optp = ((u_int8_t *)th) + sizeof(struct tcphdr); 1123 /* 1124 * Do quick retrieval of timestamp options ("options 1125 * prediction?"). If timestamp is the only option and it's 1126 * formatted as recommended in RFC 1323 appendix A, we 1127 * quickly get the values now and not bother calling 1128 * tcp_dooptions(), etc. 1129 */ 1130 if ((optlen == TCPOLEN_TSTAMP_APPA || 1131 (optlen > TCPOLEN_TSTAMP_APPA && 1132 optp[TCPOLEN_TSTAMP_APPA] == TCPOPT_EOL)) && 1133 *(u_int32_t *)optp == htonl(TCPOPT_TSTAMP_HDR) && 1134 (th->th_flags & TH_SYN) == 0) { 1135 opti.ts_present = 1; 1136 opti.ts_val = ntohl(*(u_int32_t *)(optp + 4)); 1137 opti.ts_ecr = ntohl(*(u_int32_t *)(optp + 8)); 1138 optp = NULL; /* we've parsed the options */ 1139 } 1140 } 1141 tiflags = th->th_flags; 1142 1143 /* 1144 * Locate pcb for segment. 1145 */ 1146 findpcb: 1147 inp = NULL; 1148 #ifdef INET6 1149 in6p = NULL; 1150 #endif 1151 switch (af) { 1152 #ifdef INET 1153 case AF_INET: 1154 inp = in_pcblookup_connect(&tcbtable, ip->ip_src, th->th_sport, 1155 ip->ip_dst, th->th_dport); 1156 if (inp == 0) { 1157 ++tcpstat.tcps_pcbhashmiss; 1158 inp = in_pcblookup_bind(&tcbtable, ip->ip_dst, th->th_dport); 1159 } 1160 #ifdef INET6 1161 if (inp == 0) { 1162 struct in6_addr s, d; 1163 1164 /* mapped addr case */ 1165 bzero(&s, sizeof(s)); 1166 s.s6_addr16[5] = htons(0xffff); 1167 bcopy(&ip->ip_src, &s.s6_addr32[3], sizeof(ip->ip_src)); 1168 bzero(&d, sizeof(d)); 1169 d.s6_addr16[5] = htons(0xffff); 1170 bcopy(&ip->ip_dst, &d.s6_addr32[3], sizeof(ip->ip_dst)); 1171 in6p = in6_pcblookup_connect(&tcbtable, &s, 1172 th->th_sport, &d, th->th_dport, 0); 1173 if (in6p == 0) { 1174 ++tcpstat.tcps_pcbhashmiss; 1175 in6p = in6_pcblookup_bind(&tcbtable, &d, 1176 th->th_dport, 0); 1177 } 1178 } 1179 #endif 1180 #ifndef INET6 1181 if (inp == 0) 1182 #else 1183 if (inp == 0 && in6p == 0) 1184 #endif 1185 { 1186 ++tcpstat.tcps_noport; 1187 if (tcp_log_refused && 1188 (tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) { 1189 tcp4_log_refused(ip, th); 1190 } 1191 TCP_FIELDS_TO_HOST(th); 1192 goto dropwithreset_ratelim; 1193 } 1194 #if defined(IPSEC) || defined(FAST_IPSEC) 1195 if (inp && (inp->inp_socket->so_options & SO_ACCEPTCONN) == 0 && 1196 ipsec4_in_reject(m, inp)) { 1197 ipsecstat.in_polvio++; 1198 goto drop; 1199 } 1200 #ifdef INET6 1201 else if (in6p && 1202 (in6p->in6p_socket->so_options & SO_ACCEPTCONN) == 0 && 1203 ipsec4_in_reject_so(m, in6p->in6p_socket)) { 1204 ipsecstat.in_polvio++; 1205 goto drop; 1206 } 1207 #endif 1208 #endif /*IPSEC*/ 1209 break; 1210 #endif /*INET*/ 1211 #ifdef INET6 1212 case AF_INET6: 1213 { 1214 int faith; 1215 1216 #if defined(NFAITH) && NFAITH > 0 1217 faith = faithprefix(&ip6->ip6_dst); 1218 #else 1219 faith = 0; 1220 #endif 1221 in6p = in6_pcblookup_connect(&tcbtable, &ip6->ip6_src, 1222 th->th_sport, &ip6->ip6_dst, th->th_dport, faith); 1223 if (in6p == NULL) { 1224 ++tcpstat.tcps_pcbhashmiss; 1225 in6p = in6_pcblookup_bind(&tcbtable, &ip6->ip6_dst, 1226 th->th_dport, faith); 1227 } 1228 if (in6p == NULL) { 1229 ++tcpstat.tcps_noport; 1230 if (tcp_log_refused && 1231 (tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) { 1232 tcp6_log_refused(ip6, th); 1233 } 1234 TCP_FIELDS_TO_HOST(th); 1235 goto dropwithreset_ratelim; 1236 } 1237 #if defined(IPSEC) || defined(FAST_IPSEC) 1238 if ((in6p->in6p_socket->so_options & SO_ACCEPTCONN) == 0 && 1239 ipsec6_in_reject(m, in6p)) { 1240 ipsec6stat.in_polvio++; 1241 goto drop; 1242 } 1243 #endif /*IPSEC*/ 1244 break; 1245 } 1246 #endif 1247 } 1248 1249 /* 1250 * If the state is CLOSED (i.e., TCB does not exist) then 1251 * all data in the incoming segment is discarded. 1252 * If the TCB exists but is in CLOSED state, it is embryonic, 1253 * but should either do a listen or a connect soon. 1254 */ 1255 tp = NULL; 1256 so = NULL; 1257 if (inp) { 1258 tp = intotcpcb(inp); 1259 so = inp->inp_socket; 1260 } 1261 #ifdef INET6 1262 else if (in6p) { 1263 tp = in6totcpcb(in6p); 1264 so = in6p->in6p_socket; 1265 } 1266 #endif 1267 if (tp == 0) { 1268 TCP_FIELDS_TO_HOST(th); 1269 goto dropwithreset_ratelim; 1270 } 1271 if (tp->t_state == TCPS_CLOSED) 1272 goto drop; 1273 1274 /* 1275 * Checksum extended TCP header and data. 1276 */ 1277 if (tcp_input_checksum(af, m, th, toff, off, tlen)) 1278 goto badcsum; 1279 1280 TCP_FIELDS_TO_HOST(th); 1281 1282 /* Unscale the window into a 32-bit value. */ 1283 if ((tiflags & TH_SYN) == 0) 1284 tiwin = th->th_win << tp->snd_scale; 1285 else 1286 tiwin = th->th_win; 1287 1288 #ifdef INET6 1289 /* save packet options if user wanted */ 1290 if (in6p && (in6p->in6p_flags & IN6P_CONTROLOPTS)) { 1291 if (in6p->in6p_options) { 1292 m_freem(in6p->in6p_options); 1293 in6p->in6p_options = 0; 1294 } 1295 KASSERT(ip6 != NULL); 1296 ip6_savecontrol(in6p, &in6p->in6p_options, ip6, m); 1297 } 1298 #endif 1299 1300 if (so->so_options & (SO_DEBUG|SO_ACCEPTCONN)) { 1301 union syn_cache_sa src; 1302 union syn_cache_sa dst; 1303 1304 bzero(&src, sizeof(src)); 1305 bzero(&dst, sizeof(dst)); 1306 switch (af) { 1307 #ifdef INET 1308 case AF_INET: 1309 src.sin.sin_len = sizeof(struct sockaddr_in); 1310 src.sin.sin_family = AF_INET; 1311 src.sin.sin_addr = ip->ip_src; 1312 src.sin.sin_port = th->th_sport; 1313 1314 dst.sin.sin_len = sizeof(struct sockaddr_in); 1315 dst.sin.sin_family = AF_INET; 1316 dst.sin.sin_addr = ip->ip_dst; 1317 dst.sin.sin_port = th->th_dport; 1318 break; 1319 #endif 1320 #ifdef INET6 1321 case AF_INET6: 1322 src.sin6.sin6_len = sizeof(struct sockaddr_in6); 1323 src.sin6.sin6_family = AF_INET6; 1324 src.sin6.sin6_addr = ip6->ip6_src; 1325 src.sin6.sin6_port = th->th_sport; 1326 1327 dst.sin6.sin6_len = sizeof(struct sockaddr_in6); 1328 dst.sin6.sin6_family = AF_INET6; 1329 dst.sin6.sin6_addr = ip6->ip6_dst; 1330 dst.sin6.sin6_port = th->th_dport; 1331 break; 1332 #endif /* INET6 */ 1333 default: 1334 goto badsyn; /*sanity*/ 1335 } 1336 1337 if (so->so_options & SO_DEBUG) { 1338 #ifdef TCP_DEBUG 1339 ostate = tp->t_state; 1340 #endif 1341 1342 tcp_saveti = NULL; 1343 if (iphlen + sizeof(struct tcphdr) > MHLEN) 1344 goto nosave; 1345 1346 if (m->m_len > iphlen && (m->m_flags & M_EXT) == 0) { 1347 tcp_saveti = m_copym(m, 0, iphlen, M_DONTWAIT); 1348 if (!tcp_saveti) 1349 goto nosave; 1350 } else { 1351 MGETHDR(tcp_saveti, M_DONTWAIT, MT_HEADER); 1352 if (!tcp_saveti) 1353 goto nosave; 1354 MCLAIM(m, &tcp_mowner); 1355 tcp_saveti->m_len = iphlen; 1356 m_copydata(m, 0, iphlen, 1357 mtod(tcp_saveti, caddr_t)); 1358 } 1359 1360 if (M_TRAILINGSPACE(tcp_saveti) < sizeof(struct tcphdr)) { 1361 m_freem(tcp_saveti); 1362 tcp_saveti = NULL; 1363 } else { 1364 tcp_saveti->m_len += sizeof(struct tcphdr); 1365 bcopy(th, mtod(tcp_saveti, caddr_t) + iphlen, 1366 sizeof(struct tcphdr)); 1367 } 1368 nosave:; 1369 } 1370 if (so->so_options & SO_ACCEPTCONN) { 1371 if ((tiflags & (TH_RST|TH_ACK|TH_SYN)) != TH_SYN) { 1372 if (tiflags & TH_RST) { 1373 syn_cache_reset(&src.sa, &dst.sa, th); 1374 } else if ((tiflags & (TH_ACK|TH_SYN)) == 1375 (TH_ACK|TH_SYN)) { 1376 /* 1377 * Received a SYN,ACK. This should 1378 * never happen while we are in 1379 * LISTEN. Send an RST. 1380 */ 1381 goto badsyn; 1382 } else if (tiflags & TH_ACK) { 1383 so = syn_cache_get(&src.sa, &dst.sa, 1384 th, toff, tlen, so, m); 1385 if (so == NULL) { 1386 /* 1387 * We don't have a SYN for 1388 * this ACK; send an RST. 1389 */ 1390 goto badsyn; 1391 } else if (so == 1392 (struct socket *)(-1)) { 1393 /* 1394 * We were unable to create 1395 * the connection. If the 1396 * 3-way handshake was 1397 * completed, and RST has 1398 * been sent to the peer. 1399 * Since the mbuf might be 1400 * in use for the reply, 1401 * do not free it. 1402 */ 1403 m = NULL; 1404 } else { 1405 /* 1406 * We have created a 1407 * full-blown connection. 1408 */ 1409 tp = NULL; 1410 inp = NULL; 1411 #ifdef INET6 1412 in6p = NULL; 1413 #endif 1414 switch (so->so_proto->pr_domain->dom_family) { 1415 #ifdef INET 1416 case AF_INET: 1417 inp = sotoinpcb(so); 1418 tp = intotcpcb(inp); 1419 break; 1420 #endif 1421 #ifdef INET6 1422 case AF_INET6: 1423 in6p = sotoin6pcb(so); 1424 tp = in6totcpcb(in6p); 1425 break; 1426 #endif 1427 } 1428 if (tp == NULL) 1429 goto badsyn; /*XXX*/ 1430 tiwin <<= tp->snd_scale; 1431 goto after_listen; 1432 } 1433 } else { 1434 /* 1435 * None of RST, SYN or ACK was set. 1436 * This is an invalid packet for a 1437 * TCB in LISTEN state. Send a RST. 1438 */ 1439 goto badsyn; 1440 } 1441 } else { 1442 /* 1443 * Received a SYN. 1444 */ 1445 1446 #ifdef INET6 1447 /* 1448 * If deprecated address is forbidden, we do 1449 * not accept SYN to deprecated interface 1450 * address to prevent any new inbound 1451 * connection from getting established. 1452 * When we do not accept SYN, we send a TCP 1453 * RST, with deprecated source address (instead 1454 * of dropping it). We compromise it as it is 1455 * much better for peer to send a RST, and 1456 * RST will be the final packet for the 1457 * exchange. 1458 * 1459 * If we do not forbid deprecated addresses, we 1460 * accept the SYN packet. RFC2462 does not 1461 * suggest dropping SYN in this case. 1462 * If we decipher RFC2462 5.5.4, it says like 1463 * this: 1464 * 1. use of deprecated addr with existing 1465 * communication is okay - "SHOULD continue 1466 * to be used" 1467 * 2. use of it with new communication: 1468 * (2a) "SHOULD NOT be used if alternate 1469 * address with sufficient scope is 1470 * available" 1471 * (2b) nothing mentioned otherwise. 1472 * Here we fall into (2b) case as we have no 1473 * choice in our source address selection - we 1474 * must obey the peer. 1475 * 1476 * The wording in RFC2462 is confusing, and 1477 * there are multiple description text for 1478 * deprecated address handling - worse, they 1479 * are not exactly the same. I believe 5.5.4 1480 * is the best one, so we follow 5.5.4. 1481 */ 1482 if (af == AF_INET6 && !ip6_use_deprecated) { 1483 struct in6_ifaddr *ia6; 1484 if ((ia6 = in6ifa_ifpwithaddr(m->m_pkthdr.rcvif, 1485 &ip6->ip6_dst)) && 1486 (ia6->ia6_flags & IN6_IFF_DEPRECATED)) { 1487 tp = NULL; 1488 goto dropwithreset; 1489 } 1490 } 1491 #endif 1492 1493 #ifdef IPSEC 1494 switch (af) { 1495 #ifdef INET 1496 case AF_INET: 1497 if (ipsec4_in_reject_so(m, so)) { 1498 ipsecstat.in_polvio++; 1499 tp = NULL; 1500 goto dropwithreset; 1501 } 1502 break; 1503 #endif 1504 #ifdef INET6 1505 case AF_INET6: 1506 if (ipsec6_in_reject_so(m, so)) { 1507 ipsec6stat.in_polvio++; 1508 tp = NULL; 1509 goto dropwithreset; 1510 } 1511 break; 1512 #endif 1513 } 1514 #endif 1515 1516 /* 1517 * LISTEN socket received a SYN 1518 * from itself? This can't possibly 1519 * be valid; drop the packet. 1520 */ 1521 if (th->th_sport == th->th_dport) { 1522 int i; 1523 1524 switch (af) { 1525 #ifdef INET 1526 case AF_INET: 1527 i = in_hosteq(ip->ip_src, ip->ip_dst); 1528 break; 1529 #endif 1530 #ifdef INET6 1531 case AF_INET6: 1532 i = IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &ip6->ip6_dst); 1533 break; 1534 #endif 1535 default: 1536 i = 1; 1537 } 1538 if (i) { 1539 tcpstat.tcps_badsyn++; 1540 goto drop; 1541 } 1542 } 1543 1544 /* 1545 * SYN looks ok; create compressed TCP 1546 * state for it. 1547 */ 1548 if (so->so_qlen <= so->so_qlimit && 1549 syn_cache_add(&src.sa, &dst.sa, th, tlen, 1550 so, m, optp, optlen, &opti)) 1551 m = NULL; 1552 } 1553 goto drop; 1554 } 1555 } 1556 1557 after_listen: 1558 #ifdef DIAGNOSTIC 1559 /* 1560 * Should not happen now that all embryonic connections 1561 * are handled with compressed state. 1562 */ 1563 if (tp->t_state == TCPS_LISTEN) 1564 panic("tcp_input: TCPS_LISTEN"); 1565 #endif 1566 1567 /* 1568 * Segment received on connection. 1569 * Reset idle time and keep-alive timer. 1570 */ 1571 tp->t_rcvtime = tcp_now; 1572 if (TCPS_HAVEESTABLISHED(tp->t_state)) 1573 TCP_TIMER_ARM(tp, TCPT_KEEP, tcp_keepidle); 1574 1575 /* 1576 * Process options. 1577 */ 1578 #ifdef TCP_SIGNATURE 1579 if (optp || (tp->t_flags & TF_SIGNATURE)) 1580 #else 1581 if (optp) 1582 #endif 1583 if (tcp_dooptions(tp, optp, optlen, th, m, toff, &opti) < 0) 1584 goto drop; 1585 1586 if (TCP_SACK_ENABLED(tp)) { 1587 tcp_del_sackholes(tp, th); 1588 } 1589 1590 if (opti.ts_present && opti.ts_ecr) { 1591 /* 1592 * Calculate the RTT from the returned time stamp and the 1593 * connection's time base. If the time stamp is later than 1594 * the current time, or is extremely old, fall back to non-1323 1595 * RTT calculation. Since ts_ecr is unsigned, we can test both 1596 * at the same time. 1597 */ 1598 ts_rtt = TCP_TIMESTAMP(tp) - opti.ts_ecr + 1; 1599 if (ts_rtt > TCP_PAWS_IDLE) 1600 ts_rtt = 0; 1601 } else { 1602 ts_rtt = 0; 1603 } 1604 1605 /* 1606 * Header prediction: check for the two common cases 1607 * of a uni-directional data xfer. If the packet has 1608 * no control flags, is in-sequence, the window didn't 1609 * change and we're not retransmitting, it's a 1610 * candidate. If the length is zero and the ack moved 1611 * forward, we're the sender side of the xfer. Just 1612 * free the data acked & wake any higher level process 1613 * that was blocked waiting for space. If the length 1614 * is non-zero and the ack didn't move, we're the 1615 * receiver side. If we're getting packets in-order 1616 * (the reassembly queue is empty), add the data to 1617 * the socket buffer and note that we need a delayed ack. 1618 */ 1619 if (tp->t_state == TCPS_ESTABLISHED && 1620 (tiflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK && 1621 (!opti.ts_present || TSTMP_GEQ(opti.ts_val, tp->ts_recent)) && 1622 th->th_seq == tp->rcv_nxt && 1623 tiwin && tiwin == tp->snd_wnd && 1624 tp->snd_nxt == tp->snd_max) { 1625 1626 /* 1627 * If last ACK falls within this segment's sequence numbers, 1628 * record the timestamp. 1629 * NOTE: 1630 * 1) That the test incorporates suggestions from the latest 1631 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 1632 * 2) That updating only on newer timestamps interferes with 1633 * our earlier PAWS tests, so this check should be solely 1634 * predicated on the sequence space of this segment. 1635 * 3) That we modify the segment boundary check to be 1636 * Last.ACK.Sent <= SEG.SEQ + SEG.Len 1637 * instead of RFC1323's 1638 * Last.ACK.Sent < SEG.SEQ + SEG.Len, 1639 * This modified check allows us to overcome RFC1323's 1640 * limitations as described in Stevens TCP/IP Illustrated 1641 * Vol. 2 p.869. In such cases, we can still calculate the 1642 * RTT correctly when RCV.NXT == Last.ACK.Sent. 1643 */ 1644 if (opti.ts_present && 1645 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 1646 SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen + 1647 ((tiflags & (TH_SYN|TH_FIN)) != 0))) { 1648 tp->ts_recent_age = tcp_now; 1649 tp->ts_recent = opti.ts_val; 1650 } 1651 1652 if (tlen == 0) { 1653 /* Ack prediction. */ 1654 if (SEQ_GT(th->th_ack, tp->snd_una) && 1655 SEQ_LEQ(th->th_ack, tp->snd_max) && 1656 tp->snd_cwnd >= tp->snd_wnd && 1657 tp->t_partialacks < 0) { 1658 /* 1659 * this is a pure ack for outstanding data. 1660 */ 1661 ++tcpstat.tcps_predack; 1662 if (ts_rtt) 1663 tcp_xmit_timer(tp, ts_rtt); 1664 else if (tp->t_rtttime && 1665 SEQ_GT(th->th_ack, tp->t_rtseq)) 1666 tcp_xmit_timer(tp, 1667 tcp_now - tp->t_rtttime); 1668 acked = th->th_ack - tp->snd_una; 1669 tcpstat.tcps_rcvackpack++; 1670 tcpstat.tcps_rcvackbyte += acked; 1671 ND6_HINT(tp); 1672 1673 if (acked > (tp->t_lastoff - tp->t_inoff)) 1674 tp->t_lastm = NULL; 1675 sbdrop(&so->so_snd, acked); 1676 tp->t_lastoff -= acked; 1677 1678 ICMP_CHECK(tp, th, acked); 1679 1680 tp->snd_una = th->th_ack; 1681 tp->snd_fack = tp->snd_una; 1682 if (SEQ_LT(tp->snd_high, tp->snd_una)) 1683 tp->snd_high = tp->snd_una; 1684 m_freem(m); 1685 1686 /* 1687 * If all outstanding data are acked, stop 1688 * retransmit timer, otherwise restart timer 1689 * using current (possibly backed-off) value. 1690 * If process is waiting for space, 1691 * wakeup/selwakeup/signal. If data 1692 * are ready to send, let tcp_output 1693 * decide between more output or persist. 1694 */ 1695 if (tp->snd_una == tp->snd_max) 1696 TCP_TIMER_DISARM(tp, TCPT_REXMT); 1697 else if (TCP_TIMER_ISARMED(tp, 1698 TCPT_PERSIST) == 0) 1699 TCP_TIMER_ARM(tp, TCPT_REXMT, 1700 tp->t_rxtcur); 1701 1702 sowwakeup(so); 1703 if (so->so_snd.sb_cc) 1704 (void) tcp_output(tp); 1705 if (tcp_saveti) 1706 m_freem(tcp_saveti); 1707 return; 1708 } 1709 } else if (th->th_ack == tp->snd_una && 1710 TAILQ_FIRST(&tp->segq) == NULL && 1711 tlen <= sbspace(&so->so_rcv)) { 1712 /* 1713 * this is a pure, in-sequence data packet 1714 * with nothing on the reassembly queue and 1715 * we have enough buffer space to take it. 1716 */ 1717 ++tcpstat.tcps_preddat; 1718 tp->rcv_nxt += tlen; 1719 tcpstat.tcps_rcvpack++; 1720 tcpstat.tcps_rcvbyte += tlen; 1721 ND6_HINT(tp); 1722 /* 1723 * Drop TCP, IP headers and TCP options then add data 1724 * to socket buffer. 1725 */ 1726 if (so->so_state & SS_CANTRCVMORE) 1727 m_freem(m); 1728 else { 1729 m_adj(m, toff + off); 1730 sbappendstream(&so->so_rcv, m); 1731 } 1732 sorwakeup(so); 1733 TCP_SETUP_ACK(tp, th); 1734 if (tp->t_flags & TF_ACKNOW) 1735 (void) tcp_output(tp); 1736 if (tcp_saveti) 1737 m_freem(tcp_saveti); 1738 return; 1739 } 1740 } 1741 1742 /* 1743 * Compute mbuf offset to TCP data segment. 1744 */ 1745 hdroptlen = toff + off; 1746 1747 /* 1748 * Calculate amount of space in receive window, 1749 * and then do TCP input processing. 1750 * Receive window is amount of space in rcv queue, 1751 * but not less than advertised window. 1752 */ 1753 { int win; 1754 1755 win = sbspace(&so->so_rcv); 1756 if (win < 0) 1757 win = 0; 1758 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 1759 } 1760 1761 switch (tp->t_state) { 1762 case TCPS_LISTEN: 1763 /* 1764 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN 1765 */ 1766 if (m->m_flags & (M_BCAST|M_MCAST)) 1767 goto drop; 1768 switch (af) { 1769 #ifdef INET6 1770 case AF_INET6: 1771 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) 1772 goto drop; 1773 break; 1774 #endif /* INET6 */ 1775 case AF_INET: 1776 if (IN_MULTICAST(ip->ip_dst.s_addr) || 1777 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 1778 goto drop; 1779 break; 1780 } 1781 break; 1782 1783 /* 1784 * If the state is SYN_SENT: 1785 * if seg contains an ACK, but not for our SYN, drop the input. 1786 * if seg contains a RST, then drop the connection. 1787 * if seg does not contain SYN, then drop it. 1788 * Otherwise this is an acceptable SYN segment 1789 * initialize tp->rcv_nxt and tp->irs 1790 * if seg contains ack then advance tp->snd_una 1791 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 1792 * arrange for segment to be acked (eventually) 1793 * continue processing rest of data/controls, beginning with URG 1794 */ 1795 case TCPS_SYN_SENT: 1796 if ((tiflags & TH_ACK) && 1797 (SEQ_LEQ(th->th_ack, tp->iss) || 1798 SEQ_GT(th->th_ack, tp->snd_max))) 1799 goto dropwithreset; 1800 if (tiflags & TH_RST) { 1801 if (tiflags & TH_ACK) 1802 tp = tcp_drop(tp, ECONNREFUSED); 1803 goto drop; 1804 } 1805 if ((tiflags & TH_SYN) == 0) 1806 goto drop; 1807 if (tiflags & TH_ACK) { 1808 tp->snd_una = th->th_ack; 1809 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 1810 tp->snd_nxt = tp->snd_una; 1811 if (SEQ_LT(tp->snd_high, tp->snd_una)) 1812 tp->snd_high = tp->snd_una; 1813 TCP_TIMER_DISARM(tp, TCPT_REXMT); 1814 } 1815 tp->irs = th->th_seq; 1816 tcp_rcvseqinit(tp); 1817 tp->t_flags |= TF_ACKNOW; 1818 tcp_mss_from_peer(tp, opti.maxseg); 1819 1820 /* 1821 * Initialize the initial congestion window. If we 1822 * had to retransmit the SYN, we must initialize cwnd 1823 * to 1 segment (i.e. the Loss Window). 1824 */ 1825 if (tp->t_flags & TF_SYN_REXMT) 1826 tp->snd_cwnd = tp->t_peermss; 1827 else { 1828 int ss = tcp_init_win; 1829 #ifdef INET 1830 if (inp != NULL && in_localaddr(inp->inp_faddr)) 1831 ss = tcp_init_win_local; 1832 #endif 1833 #ifdef INET6 1834 if (in6p != NULL && in6_localaddr(&in6p->in6p_faddr)) 1835 ss = tcp_init_win_local; 1836 #endif 1837 tp->snd_cwnd = TCP_INITIAL_WINDOW(ss, tp->t_peermss); 1838 } 1839 1840 tcp_rmx_rtt(tp); 1841 if (tiflags & TH_ACK) { 1842 tcpstat.tcps_connects++; 1843 soisconnected(so); 1844 tcp_established(tp); 1845 /* Do window scaling on this connection? */ 1846 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 1847 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 1848 tp->snd_scale = tp->requested_s_scale; 1849 tp->rcv_scale = tp->request_r_scale; 1850 } 1851 TCP_REASS_LOCK(tp); 1852 (void) tcp_reass(tp, NULL, (struct mbuf *)0, &tlen); 1853 TCP_REASS_UNLOCK(tp); 1854 /* 1855 * if we didn't have to retransmit the SYN, 1856 * use its rtt as our initial srtt & rtt var. 1857 */ 1858 if (tp->t_rtttime) 1859 tcp_xmit_timer(tp, tcp_now - tp->t_rtttime); 1860 } else 1861 tp->t_state = TCPS_SYN_RECEIVED; 1862 1863 /* 1864 * Advance th->th_seq to correspond to first data byte. 1865 * If data, trim to stay within window, 1866 * dropping FIN if necessary. 1867 */ 1868 th->th_seq++; 1869 if (tlen > tp->rcv_wnd) { 1870 todrop = tlen - tp->rcv_wnd; 1871 m_adj(m, -todrop); 1872 tlen = tp->rcv_wnd; 1873 tiflags &= ~TH_FIN; 1874 tcpstat.tcps_rcvpackafterwin++; 1875 tcpstat.tcps_rcvbyteafterwin += todrop; 1876 } 1877 tp->snd_wl1 = th->th_seq - 1; 1878 tp->rcv_up = th->th_seq; 1879 goto step6; 1880 1881 /* 1882 * If the state is SYN_RECEIVED: 1883 * If seg contains an ACK, but not for our SYN, drop the input 1884 * and generate an RST. See page 36, rfc793 1885 */ 1886 case TCPS_SYN_RECEIVED: 1887 if ((tiflags & TH_ACK) && 1888 (SEQ_LEQ(th->th_ack, tp->iss) || 1889 SEQ_GT(th->th_ack, tp->snd_max))) 1890 goto dropwithreset; 1891 break; 1892 } 1893 1894 /* 1895 * States other than LISTEN or SYN_SENT. 1896 * First check timestamp, if present. 1897 * Then check that at least some bytes of segment are within 1898 * receive window. If segment begins before rcv_nxt, 1899 * drop leading data (and SYN); if nothing left, just ack. 1900 * 1901 * RFC 1323 PAWS: If we have a timestamp reply on this segment 1902 * and it's less than ts_recent, drop it. 1903 */ 1904 if (opti.ts_present && (tiflags & TH_RST) == 0 && tp->ts_recent && 1905 TSTMP_LT(opti.ts_val, tp->ts_recent)) { 1906 1907 /* Check to see if ts_recent is over 24 days old. */ 1908 if (tcp_now - tp->ts_recent_age > TCP_PAWS_IDLE) { 1909 /* 1910 * Invalidate ts_recent. If this segment updates 1911 * ts_recent, the age will be reset later and ts_recent 1912 * will get a valid value. If it does not, setting 1913 * ts_recent to zero will at least satisfy the 1914 * requirement that zero be placed in the timestamp 1915 * echo reply when ts_recent isn't valid. The 1916 * age isn't reset until we get a valid ts_recent 1917 * because we don't want out-of-order segments to be 1918 * dropped when ts_recent is old. 1919 */ 1920 tp->ts_recent = 0; 1921 } else { 1922 tcpstat.tcps_rcvduppack++; 1923 tcpstat.tcps_rcvdupbyte += tlen; 1924 tcpstat.tcps_pawsdrop++; 1925 tcp_new_dsack(tp, th->th_seq, tlen); 1926 goto dropafterack; 1927 } 1928 } 1929 1930 todrop = tp->rcv_nxt - th->th_seq; 1931 dupseg = FALSE; 1932 if (todrop > 0) { 1933 if (tiflags & TH_SYN) { 1934 tiflags &= ~TH_SYN; 1935 th->th_seq++; 1936 if (th->th_urp > 1) 1937 th->th_urp--; 1938 else { 1939 tiflags &= ~TH_URG; 1940 th->th_urp = 0; 1941 } 1942 todrop--; 1943 } 1944 if (todrop > tlen || 1945 (todrop == tlen && (tiflags & TH_FIN) == 0)) { 1946 /* 1947 * Any valid FIN or RST must be to the left of the 1948 * window. At this point the FIN or RST must be a 1949 * duplicate or out of sequence; drop it. 1950 */ 1951 if (tiflags & TH_RST) 1952 goto drop; 1953 tiflags &= ~(TH_FIN|TH_RST); 1954 /* 1955 * Send an ACK to resynchronize and drop any data. 1956 * But keep on processing for RST or ACK. 1957 */ 1958 tp->t_flags |= TF_ACKNOW; 1959 todrop = tlen; 1960 dupseg = TRUE; 1961 tcpstat.tcps_rcvdupbyte += todrop; 1962 tcpstat.tcps_rcvduppack++; 1963 } else if ((tiflags & TH_RST) && 1964 th->th_seq != tp->last_ack_sent) { 1965 /* 1966 * Test for reset before adjusting the sequence 1967 * number for overlapping data. 1968 */ 1969 goto dropafterack_ratelim; 1970 } else { 1971 tcpstat.tcps_rcvpartduppack++; 1972 tcpstat.tcps_rcvpartdupbyte += todrop; 1973 } 1974 tcp_new_dsack(tp, th->th_seq, todrop); 1975 hdroptlen += todrop; /*drop from head afterwards*/ 1976 th->th_seq += todrop; 1977 tlen -= todrop; 1978 if (th->th_urp > todrop) 1979 th->th_urp -= todrop; 1980 else { 1981 tiflags &= ~TH_URG; 1982 th->th_urp = 0; 1983 } 1984 } 1985 1986 /* 1987 * If new data are received on a connection after the 1988 * user processes are gone, then RST the other end. 1989 */ 1990 if ((so->so_state & SS_NOFDREF) && 1991 tp->t_state > TCPS_CLOSE_WAIT && tlen) { 1992 tp = tcp_close(tp); 1993 tcpstat.tcps_rcvafterclose++; 1994 goto dropwithreset; 1995 } 1996 1997 /* 1998 * If segment ends after window, drop trailing data 1999 * (and PUSH and FIN); if nothing left, just ACK. 2000 */ 2001 todrop = (th->th_seq + tlen) - (tp->rcv_nxt+tp->rcv_wnd); 2002 if (todrop > 0) { 2003 tcpstat.tcps_rcvpackafterwin++; 2004 if (todrop >= tlen) { 2005 /* 2006 * The segment actually starts after the window. 2007 * th->th_seq + tlen - tp->rcv_nxt - tp->rcv_wnd >= tlen 2008 * th->th_seq - tp->rcv_nxt - tp->rcv_wnd >= 0 2009 * th->th_seq >= tp->rcv_nxt + tp->rcv_wnd 2010 */ 2011 tcpstat.tcps_rcvbyteafterwin += tlen; 2012 /* 2013 * If a new connection request is received 2014 * while in TIME_WAIT, drop the old connection 2015 * and start over if the sequence numbers 2016 * are above the previous ones. 2017 * 2018 * NOTE: We will checksum the packet again, and 2019 * so we need to put the header fields back into 2020 * network order! 2021 * XXX This kind of sucks, but we don't expect 2022 * XXX this to happen very often, so maybe it 2023 * XXX doesn't matter so much. 2024 */ 2025 if (tiflags & TH_SYN && 2026 tp->t_state == TCPS_TIME_WAIT && 2027 SEQ_GT(th->th_seq, tp->rcv_nxt)) { 2028 tp = tcp_close(tp); 2029 TCP_FIELDS_TO_NET(th); 2030 goto findpcb; 2031 } 2032 /* 2033 * If window is closed can only take segments at 2034 * window edge, and have to drop data and PUSH from 2035 * incoming segments. Continue processing, but 2036 * remember to ack. Otherwise, drop segment 2037 * and (if not RST) ack. 2038 */ 2039 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 2040 tp->t_flags |= TF_ACKNOW; 2041 tcpstat.tcps_rcvwinprobe++; 2042 } else 2043 goto dropafterack; 2044 } else 2045 tcpstat.tcps_rcvbyteafterwin += todrop; 2046 m_adj(m, -todrop); 2047 tlen -= todrop; 2048 tiflags &= ~(TH_PUSH|TH_FIN); 2049 } 2050 2051 /* 2052 * If last ACK falls within this segment's sequence numbers, 2053 * and the timestamp is newer, record it. 2054 */ 2055 if (opti.ts_present && TSTMP_GEQ(opti.ts_val, tp->ts_recent) && 2056 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 2057 SEQ_LT(tp->last_ack_sent, th->th_seq + tlen + 2058 ((tiflags & (TH_SYN|TH_FIN)) != 0))) { 2059 tp->ts_recent_age = tcp_now; 2060 tp->ts_recent = opti.ts_val; 2061 } 2062 2063 /* 2064 * If the RST bit is set examine the state: 2065 * SYN_RECEIVED STATE: 2066 * If passive open, return to LISTEN state. 2067 * If active open, inform user that connection was refused. 2068 * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES: 2069 * Inform user that connection was reset, and close tcb. 2070 * CLOSING, LAST_ACK, TIME_WAIT STATES 2071 * Close the tcb. 2072 */ 2073 if (tiflags & TH_RST) { 2074 if (th->th_seq != tp->last_ack_sent) 2075 goto dropafterack_ratelim; 2076 2077 switch (tp->t_state) { 2078 case TCPS_SYN_RECEIVED: 2079 so->so_error = ECONNREFUSED; 2080 goto close; 2081 2082 case TCPS_ESTABLISHED: 2083 case TCPS_FIN_WAIT_1: 2084 case TCPS_FIN_WAIT_2: 2085 case TCPS_CLOSE_WAIT: 2086 so->so_error = ECONNRESET; 2087 close: 2088 tp->t_state = TCPS_CLOSED; 2089 tcpstat.tcps_drops++; 2090 tp = tcp_close(tp); 2091 goto drop; 2092 2093 case TCPS_CLOSING: 2094 case TCPS_LAST_ACK: 2095 case TCPS_TIME_WAIT: 2096 tp = tcp_close(tp); 2097 goto drop; 2098 } 2099 } 2100 2101 /* 2102 * Since we've covered the SYN-SENT and SYN-RECEIVED states above 2103 * we must be in a synchronized state. RFC791 states (under RST 2104 * generation) that any unacceptable segment (an out-of-order SYN 2105 * qualifies) received in a synchronized state must elicit only an 2106 * empty acknowledgment segment ... and the connection remains in 2107 * the same state. 2108 */ 2109 if (tiflags & TH_SYN) { 2110 if (tp->rcv_nxt == th->th_seq) { 2111 tcp_respond(tp, m, m, th, (tcp_seq)0, th->th_ack - 1, 2112 TH_ACK); 2113 if (tcp_saveti) 2114 m_freem(tcp_saveti); 2115 return; 2116 } 2117 2118 goto dropafterack_ratelim; 2119 } 2120 2121 /* 2122 * If the ACK bit is off we drop the segment and return. 2123 */ 2124 if ((tiflags & TH_ACK) == 0) { 2125 if (tp->t_flags & TF_ACKNOW) 2126 goto dropafterack; 2127 else 2128 goto drop; 2129 } 2130 2131 /* 2132 * Ack processing. 2133 */ 2134 switch (tp->t_state) { 2135 2136 /* 2137 * In SYN_RECEIVED state if the ack ACKs our SYN then enter 2138 * ESTABLISHED state and continue processing, otherwise 2139 * send an RST. 2140 */ 2141 case TCPS_SYN_RECEIVED: 2142 if (SEQ_GT(tp->snd_una, th->th_ack) || 2143 SEQ_GT(th->th_ack, tp->snd_max)) 2144 goto dropwithreset; 2145 tcpstat.tcps_connects++; 2146 soisconnected(so); 2147 tcp_established(tp); 2148 /* Do window scaling? */ 2149 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2150 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2151 tp->snd_scale = tp->requested_s_scale; 2152 tp->rcv_scale = tp->request_r_scale; 2153 } 2154 TCP_REASS_LOCK(tp); 2155 (void) tcp_reass(tp, NULL, (struct mbuf *)0, &tlen); 2156 TCP_REASS_UNLOCK(tp); 2157 tp->snd_wl1 = th->th_seq - 1; 2158 /* fall into ... */ 2159 2160 /* 2161 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 2162 * ACKs. If the ack is in the range 2163 * tp->snd_una < th->th_ack <= tp->snd_max 2164 * then advance tp->snd_una to th->th_ack and drop 2165 * data from the retransmission queue. If this ACK reflects 2166 * more up to date window information we update our window information. 2167 */ 2168 case TCPS_ESTABLISHED: 2169 case TCPS_FIN_WAIT_1: 2170 case TCPS_FIN_WAIT_2: 2171 case TCPS_CLOSE_WAIT: 2172 case TCPS_CLOSING: 2173 case TCPS_LAST_ACK: 2174 case TCPS_TIME_WAIT: 2175 2176 if (SEQ_LEQ(th->th_ack, tp->snd_una)) { 2177 if (tlen == 0 && !dupseg && tiwin == tp->snd_wnd) { 2178 tcpstat.tcps_rcvdupack++; 2179 /* 2180 * If we have outstanding data (other than 2181 * a window probe), this is a completely 2182 * duplicate ack (ie, window info didn't 2183 * change), the ack is the biggest we've 2184 * seen and we've seen exactly our rexmt 2185 * threshhold of them, assume a packet 2186 * has been dropped and retransmit it. 2187 * Kludge snd_nxt & the congestion 2188 * window so we send only this one 2189 * packet. 2190 * 2191 * We know we're losing at the current 2192 * window size so do congestion avoidance 2193 * (set ssthresh to half the current window 2194 * and pull our congestion window back to 2195 * the new ssthresh). 2196 * 2197 * Dup acks mean that packets have left the 2198 * network (they're now cached at the receiver) 2199 * so bump cwnd by the amount in the receiver 2200 * to keep a constant cwnd packets in the 2201 * network. 2202 * 2203 * If we are using TCP/SACK, then enter 2204 * Fast Recovery if the receiver SACKs 2205 * data that is tcprexmtthresh * MSS 2206 * bytes past the last ACKed segment, 2207 * irrespective of the number of DupAcks. 2208 */ 2209 if (TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 || 2210 th->th_ack != tp->snd_una) 2211 tp->t_dupacks = 0; 2212 else if (tp->t_partialacks < 0 && 2213 (++tp->t_dupacks == tcprexmtthresh || 2214 TCP_FACK_FASTRECOV(tp))) { 2215 tcp_seq onxt; 2216 u_int win; 2217 2218 if (tcp_do_newreno && 2219 SEQ_LT(th->th_ack, tp->snd_high)) { 2220 /* 2221 * False fast retransmit after 2222 * timeout. Do not enter fast 2223 * recovery. 2224 */ 2225 tp->t_dupacks = 0; 2226 break; 2227 } 2228 2229 onxt = tp->snd_nxt; 2230 win = min(tp->snd_wnd, tp->snd_cwnd) / 2231 2 / tp->t_segsz; 2232 if (win < 2) 2233 win = 2; 2234 tp->snd_ssthresh = win * tp->t_segsz; 2235 tp->snd_recover = tp->snd_max; 2236 tp->t_partialacks = 0; 2237 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2238 tp->t_rtttime = 0; 2239 if (TCP_SACK_ENABLED(tp)) { 2240 tp->t_dupacks = tcprexmtthresh; 2241 tp->sack_newdata = tp->snd_nxt; 2242 tp->snd_cwnd = tp->t_segsz; 2243 (void) tcp_output(tp); 2244 goto drop; 2245 } 2246 tp->snd_nxt = th->th_ack; 2247 tp->snd_cwnd = tp->t_segsz; 2248 (void) tcp_output(tp); 2249 tp->snd_cwnd = tp->snd_ssthresh + 2250 tp->t_segsz * tp->t_dupacks; 2251 if (SEQ_GT(onxt, tp->snd_nxt)) 2252 tp->snd_nxt = onxt; 2253 goto drop; 2254 } else if (tp->t_dupacks > tcprexmtthresh) { 2255 tp->snd_cwnd += tp->t_segsz; 2256 (void) tcp_output(tp); 2257 goto drop; 2258 } 2259 } else { 2260 /* 2261 * If the ack appears to be very old, only 2262 * allow data that is in-sequence. This 2263 * makes it somewhat more difficult to insert 2264 * forged data by guessing sequence numbers. 2265 * Sent an ack to try to update the send 2266 * sequence number on the other side. 2267 */ 2268 if (tlen && th->th_seq != tp->rcv_nxt && 2269 SEQ_LT(th->th_ack, 2270 tp->snd_una - tp->max_sndwnd)) 2271 goto dropafterack; 2272 } 2273 break; 2274 } 2275 /* 2276 * If the congestion window was inflated to account 2277 * for the other side's cached packets, retract it. 2278 */ 2279 if (TCP_SACK_ENABLED(tp)) 2280 tcp_sack_newack(tp, th); 2281 else if (tcp_do_newreno) 2282 tcp_newreno_newack(tp, th); 2283 else 2284 tcp_reno_newack(tp, th); 2285 if (SEQ_GT(th->th_ack, tp->snd_max)) { 2286 tcpstat.tcps_rcvacktoomuch++; 2287 goto dropafterack; 2288 } 2289 acked = th->th_ack - tp->snd_una; 2290 tcpstat.tcps_rcvackpack++; 2291 tcpstat.tcps_rcvackbyte += acked; 2292 2293 /* 2294 * If we have a timestamp reply, update smoothed 2295 * round trip time. If no timestamp is present but 2296 * transmit timer is running and timed sequence 2297 * number was acked, update smoothed round trip time. 2298 * Since we now have an rtt measurement, cancel the 2299 * timer backoff (cf., Phil Karn's retransmit alg.). 2300 * Recompute the initial retransmit timer. 2301 */ 2302 if (ts_rtt) 2303 tcp_xmit_timer(tp, ts_rtt); 2304 else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) 2305 tcp_xmit_timer(tp, tcp_now - tp->t_rtttime); 2306 2307 /* 2308 * If all outstanding data is acked, stop retransmit 2309 * timer and remember to restart (more output or persist). 2310 * If there is more data to be acked, restart retransmit 2311 * timer, using current (possibly backed-off) value. 2312 */ 2313 if (th->th_ack == tp->snd_max) { 2314 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2315 needoutput = 1; 2316 } else if (TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) 2317 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 2318 /* 2319 * When new data is acked, open the congestion window. 2320 * If the window gives us less than ssthresh packets 2321 * in flight, open exponentially (segsz per packet). 2322 * Otherwise open linearly: segsz per window 2323 * (segsz^2 / cwnd per packet). 2324 * 2325 * If we are still in fast recovery (meaning we are using 2326 * NewReno and we have only received partial acks), do not 2327 * inflate the window yet. 2328 */ 2329 if (tp->t_partialacks < 0) { 2330 u_int cw = tp->snd_cwnd; 2331 u_int incr = tp->t_segsz; 2332 2333 if (cw >= tp->snd_ssthresh) 2334 incr = incr * incr / cw; 2335 tp->snd_cwnd = min(cw + incr, 2336 TCP_MAXWIN << tp->snd_scale); 2337 } 2338 ND6_HINT(tp); 2339 if (acked > so->so_snd.sb_cc) { 2340 tp->snd_wnd -= so->so_snd.sb_cc; 2341 sbdrop(&so->so_snd, (int)so->so_snd.sb_cc); 2342 ourfinisacked = 1; 2343 } else { 2344 if (acked > (tp->t_lastoff - tp->t_inoff)) 2345 tp->t_lastm = NULL; 2346 sbdrop(&so->so_snd, acked); 2347 tp->t_lastoff -= acked; 2348 tp->snd_wnd -= acked; 2349 ourfinisacked = 0; 2350 } 2351 sowwakeup(so); 2352 2353 ICMP_CHECK(tp, th, acked); 2354 2355 tp->snd_una = th->th_ack; 2356 if (SEQ_GT(tp->snd_una, tp->snd_fack)) 2357 tp->snd_fack = tp->snd_una; 2358 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2359 tp->snd_nxt = tp->snd_una; 2360 if (SEQ_LT(tp->snd_high, tp->snd_una)) 2361 tp->snd_high = tp->snd_una; 2362 2363 switch (tp->t_state) { 2364 2365 /* 2366 * In FIN_WAIT_1 STATE in addition to the processing 2367 * for the ESTABLISHED state if our FIN is now acknowledged 2368 * then enter FIN_WAIT_2. 2369 */ 2370 case TCPS_FIN_WAIT_1: 2371 if (ourfinisacked) { 2372 /* 2373 * If we can't receive any more 2374 * data, then closing user can proceed. 2375 * Starting the timer is contrary to the 2376 * specification, but if we don't get a FIN 2377 * we'll hang forever. 2378 */ 2379 if (so->so_state & SS_CANTRCVMORE) { 2380 soisdisconnected(so); 2381 if (tcp_maxidle > 0) 2382 TCP_TIMER_ARM(tp, TCPT_2MSL, 2383 tcp_maxidle); 2384 } 2385 tp->t_state = TCPS_FIN_WAIT_2; 2386 } 2387 break; 2388 2389 /* 2390 * In CLOSING STATE in addition to the processing for 2391 * the ESTABLISHED state if the ACK acknowledges our FIN 2392 * then enter the TIME-WAIT state, otherwise ignore 2393 * the segment. 2394 */ 2395 case TCPS_CLOSING: 2396 if (ourfinisacked) { 2397 tp->t_state = TCPS_TIME_WAIT; 2398 tcp_canceltimers(tp); 2399 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 2400 soisdisconnected(so); 2401 } 2402 break; 2403 2404 /* 2405 * In LAST_ACK, we may still be waiting for data to drain 2406 * and/or to be acked, as well as for the ack of our FIN. 2407 * If our FIN is now acknowledged, delete the TCB, 2408 * enter the closed state and return. 2409 */ 2410 case TCPS_LAST_ACK: 2411 if (ourfinisacked) { 2412 tp = tcp_close(tp); 2413 goto drop; 2414 } 2415 break; 2416 2417 /* 2418 * In TIME_WAIT state the only thing that should arrive 2419 * is a retransmission of the remote FIN. Acknowledge 2420 * it and restart the finack timer. 2421 */ 2422 case TCPS_TIME_WAIT: 2423 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 2424 goto dropafterack; 2425 } 2426 } 2427 2428 step6: 2429 /* 2430 * Update window information. 2431 * Don't look at window if no ACK: TAC's send garbage on first SYN. 2432 */ 2433 if ((tiflags & TH_ACK) && (SEQ_LT(tp->snd_wl1, th->th_seq) || 2434 (tp->snd_wl1 == th->th_seq && (SEQ_LT(tp->snd_wl2, th->th_ack) || 2435 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))) { 2436 /* keep track of pure window updates */ 2437 if (tlen == 0 && 2438 tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) 2439 tcpstat.tcps_rcvwinupd++; 2440 tp->snd_wnd = tiwin; 2441 tp->snd_wl1 = th->th_seq; 2442 tp->snd_wl2 = th->th_ack; 2443 if (tp->snd_wnd > tp->max_sndwnd) 2444 tp->max_sndwnd = tp->snd_wnd; 2445 needoutput = 1; 2446 } 2447 2448 /* 2449 * Process segments with URG. 2450 */ 2451 if ((tiflags & TH_URG) && th->th_urp && 2452 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2453 /* 2454 * This is a kludge, but if we receive and accept 2455 * random urgent pointers, we'll crash in 2456 * soreceive. It's hard to imagine someone 2457 * actually wanting to send this much urgent data. 2458 */ 2459 if (th->th_urp + so->so_rcv.sb_cc > sb_max) { 2460 th->th_urp = 0; /* XXX */ 2461 tiflags &= ~TH_URG; /* XXX */ 2462 goto dodata; /* XXX */ 2463 } 2464 /* 2465 * If this segment advances the known urgent pointer, 2466 * then mark the data stream. This should not happen 2467 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 2468 * a FIN has been received from the remote side. 2469 * In these states we ignore the URG. 2470 * 2471 * According to RFC961 (Assigned Protocols), 2472 * the urgent pointer points to the last octet 2473 * of urgent data. We continue, however, 2474 * to consider it to indicate the first octet 2475 * of data past the urgent section as the original 2476 * spec states (in one of two places). 2477 */ 2478 if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) { 2479 tp->rcv_up = th->th_seq + th->th_urp; 2480 so->so_oobmark = so->so_rcv.sb_cc + 2481 (tp->rcv_up - tp->rcv_nxt) - 1; 2482 if (so->so_oobmark == 0) 2483 so->so_state |= SS_RCVATMARK; 2484 sohasoutofband(so); 2485 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); 2486 } 2487 /* 2488 * Remove out of band data so doesn't get presented to user. 2489 * This can happen independent of advancing the URG pointer, 2490 * but if two URG's are pending at once, some out-of-band 2491 * data may creep in... ick. 2492 */ 2493 if (th->th_urp <= (u_int16_t) tlen 2494 #ifdef SO_OOBINLINE 2495 && (so->so_options & SO_OOBINLINE) == 0 2496 #endif 2497 ) 2498 tcp_pulloutofband(so, th, m, hdroptlen); 2499 } else 2500 /* 2501 * If no out of band data is expected, 2502 * pull receive urgent pointer along 2503 * with the receive window. 2504 */ 2505 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) 2506 tp->rcv_up = tp->rcv_nxt; 2507 dodata: /* XXX */ 2508 2509 /* 2510 * Process the segment text, merging it into the TCP sequencing queue, 2511 * and arranging for acknowledgement of receipt if necessary. 2512 * This process logically involves adjusting tp->rcv_wnd as data 2513 * is presented to the user (this happens in tcp_usrreq.c, 2514 * case PRU_RCVD). If a FIN has already been received on this 2515 * connection then we just ignore the text. 2516 */ 2517 if ((tlen || (tiflags & TH_FIN)) && 2518 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2519 /* 2520 * Insert segment ti into reassembly queue of tcp with 2521 * control block tp. Return TH_FIN if reassembly now includes 2522 * a segment with FIN. The macro form does the common case 2523 * inline (segment is the next to be received on an 2524 * established connection, and the queue is empty), 2525 * avoiding linkage into and removal from the queue and 2526 * repetition of various conversions. 2527 * Set DELACK for segments received in order, but ack 2528 * immediately when segments are out of order 2529 * (so fast retransmit can work). 2530 */ 2531 /* NOTE: this was TCP_REASS() macro, but used only once */ 2532 TCP_REASS_LOCK(tp); 2533 if (th->th_seq == tp->rcv_nxt && 2534 TAILQ_FIRST(&tp->segq) == NULL && 2535 tp->t_state == TCPS_ESTABLISHED) { 2536 TCP_SETUP_ACK(tp, th); 2537 tp->rcv_nxt += tlen; 2538 tiflags = th->th_flags & TH_FIN; 2539 tcpstat.tcps_rcvpack++; 2540 tcpstat.tcps_rcvbyte += tlen; 2541 ND6_HINT(tp); 2542 if (so->so_state & SS_CANTRCVMORE) 2543 m_freem(m); 2544 else { 2545 m_adj(m, hdroptlen); 2546 sbappendstream(&(so)->so_rcv, m); 2547 } 2548 sorwakeup(so); 2549 } else { 2550 m_adj(m, hdroptlen); 2551 tiflags = tcp_reass(tp, th, m, &tlen); 2552 tp->t_flags |= TF_ACKNOW; 2553 } 2554 TCP_REASS_UNLOCK(tp); 2555 2556 /* 2557 * Note the amount of data that peer has sent into 2558 * our window, in order to estimate the sender's 2559 * buffer size. 2560 */ 2561 len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); 2562 } else { 2563 m_freem(m); 2564 m = NULL; 2565 tiflags &= ~TH_FIN; 2566 } 2567 2568 /* 2569 * If FIN is received ACK the FIN and let the user know 2570 * that the connection is closing. Ignore a FIN received before 2571 * the connection is fully established. 2572 */ 2573 if ((tiflags & TH_FIN) && TCPS_HAVEESTABLISHED(tp->t_state)) { 2574 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2575 socantrcvmore(so); 2576 tp->t_flags |= TF_ACKNOW; 2577 tp->rcv_nxt++; 2578 } 2579 switch (tp->t_state) { 2580 2581 /* 2582 * In ESTABLISHED STATE enter the CLOSE_WAIT state. 2583 */ 2584 case TCPS_ESTABLISHED: 2585 tp->t_state = TCPS_CLOSE_WAIT; 2586 break; 2587 2588 /* 2589 * If still in FIN_WAIT_1 STATE FIN has not been acked so 2590 * enter the CLOSING state. 2591 */ 2592 case TCPS_FIN_WAIT_1: 2593 tp->t_state = TCPS_CLOSING; 2594 break; 2595 2596 /* 2597 * In FIN_WAIT_2 state enter the TIME_WAIT state, 2598 * starting the time-wait timer, turning off the other 2599 * standard timers. 2600 */ 2601 case TCPS_FIN_WAIT_2: 2602 tp->t_state = TCPS_TIME_WAIT; 2603 tcp_canceltimers(tp); 2604 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 2605 soisdisconnected(so); 2606 break; 2607 2608 /* 2609 * In TIME_WAIT state restart the 2 MSL time_wait timer. 2610 */ 2611 case TCPS_TIME_WAIT: 2612 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 2613 break; 2614 } 2615 } 2616 #ifdef TCP_DEBUG 2617 if (so->so_options & SO_DEBUG) 2618 tcp_trace(TA_INPUT, ostate, tp, tcp_saveti, 0); 2619 #endif 2620 2621 /* 2622 * Return any desired output. 2623 */ 2624 if (needoutput || (tp->t_flags & TF_ACKNOW)) { 2625 (void) tcp_output(tp); 2626 } 2627 if (tcp_saveti) 2628 m_freem(tcp_saveti); 2629 return; 2630 2631 badsyn: 2632 /* 2633 * Received a bad SYN. Increment counters and dropwithreset. 2634 */ 2635 tcpstat.tcps_badsyn++; 2636 tp = NULL; 2637 goto dropwithreset; 2638 2639 dropafterack: 2640 /* 2641 * Generate an ACK dropping incoming segment if it occupies 2642 * sequence space, where the ACK reflects our state. 2643 */ 2644 if (tiflags & TH_RST) 2645 goto drop; 2646 goto dropafterack2; 2647 2648 dropafterack_ratelim: 2649 /* 2650 * We may want to rate-limit ACKs against SYN/RST attack. 2651 */ 2652 if (ppsratecheck(&tcp_ackdrop_ppslim_last, &tcp_ackdrop_ppslim_count, 2653 tcp_ackdrop_ppslim) == 0) { 2654 /* XXX stat */ 2655 goto drop; 2656 } 2657 /* ...fall into dropafterack2... */ 2658 2659 dropafterack2: 2660 m_freem(m); 2661 tp->t_flags |= TF_ACKNOW; 2662 (void) tcp_output(tp); 2663 if (tcp_saveti) 2664 m_freem(tcp_saveti); 2665 return; 2666 2667 dropwithreset_ratelim: 2668 /* 2669 * We may want to rate-limit RSTs in certain situations, 2670 * particularly if we are sending an RST in response to 2671 * an attempt to connect to or otherwise communicate with 2672 * a port for which we have no socket. 2673 */ 2674 if (ppsratecheck(&tcp_rst_ppslim_last, &tcp_rst_ppslim_count, 2675 tcp_rst_ppslim) == 0) { 2676 /* XXX stat */ 2677 goto drop; 2678 } 2679 /* ...fall into dropwithreset... */ 2680 2681 dropwithreset: 2682 /* 2683 * Generate a RST, dropping incoming segment. 2684 * Make ACK acceptable to originator of segment. 2685 */ 2686 if (tiflags & TH_RST) 2687 goto drop; 2688 2689 switch (af) { 2690 #ifdef INET6 2691 case AF_INET6: 2692 /* For following calls to tcp_respond */ 2693 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) 2694 goto drop; 2695 break; 2696 #endif /* INET6 */ 2697 case AF_INET: 2698 if (IN_MULTICAST(ip->ip_dst.s_addr) || 2699 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 2700 goto drop; 2701 } 2702 2703 if (tiflags & TH_ACK) 2704 (void)tcp_respond(tp, m, m, th, (tcp_seq)0, th->th_ack, TH_RST); 2705 else { 2706 if (tiflags & TH_SYN) 2707 tlen++; 2708 (void)tcp_respond(tp, m, m, th, th->th_seq + tlen, (tcp_seq)0, 2709 TH_RST|TH_ACK); 2710 } 2711 if (tcp_saveti) 2712 m_freem(tcp_saveti); 2713 return; 2714 2715 badcsum: 2716 drop: 2717 /* 2718 * Drop space held by incoming segment and return. 2719 */ 2720 if (tp) { 2721 if (tp->t_inpcb) 2722 so = tp->t_inpcb->inp_socket; 2723 #ifdef INET6 2724 else if (tp->t_in6pcb) 2725 so = tp->t_in6pcb->in6p_socket; 2726 #endif 2727 else 2728 so = NULL; 2729 #ifdef TCP_DEBUG 2730 if (so && (so->so_options & SO_DEBUG) != 0) 2731 tcp_trace(TA_DROP, ostate, tp, tcp_saveti, 0); 2732 #endif 2733 } 2734 if (tcp_saveti) 2735 m_freem(tcp_saveti); 2736 m_freem(m); 2737 return; 2738 } 2739 2740 #ifdef TCP_SIGNATURE 2741 int 2742 tcp_signature_apply(void *fstate, caddr_t data, u_int len) 2743 { 2744 2745 MD5Update(fstate, (u_char *)data, len); 2746 return (0); 2747 } 2748 2749 struct secasvar * 2750 tcp_signature_getsav(struct mbuf *m, struct tcphdr *th) 2751 { 2752 struct secasvar *sav; 2753 #ifdef FAST_IPSEC 2754 union sockaddr_union dst; 2755 #endif 2756 struct ip *ip; 2757 struct ip6_hdr *ip6; 2758 2759 ip = mtod(m, struct ip *); 2760 switch (ip->ip_v) { 2761 case 4: 2762 ip = mtod(m, struct ip *); 2763 ip6 = NULL; 2764 break; 2765 case 6: 2766 ip = NULL; 2767 ip6 = mtod(m, struct ip6_hdr *); 2768 break; 2769 default: 2770 return (NULL); 2771 } 2772 2773 #ifdef FAST_IPSEC 2774 /* Extract the destination from the IP header in the mbuf. */ 2775 bzero(&dst, sizeof(union sockaddr_union)); 2776 dst.sa.sa_len = sizeof(struct sockaddr_in); 2777 dst.sa.sa_family = AF_INET; 2778 dst.sin.sin_addr = ip->ip_dst; 2779 2780 /* 2781 * Look up an SADB entry which matches the address of the peer. 2782 */ 2783 sav = KEY_ALLOCSA(&dst, IPPROTO_TCP, htonl(TCP_SIG_SPI)); 2784 #else 2785 if (ip) 2786 sav = key_allocsa(AF_INET, (caddr_t)&ip->ip_src, 2787 (caddr_t)&ip->ip_dst, IPPROTO_TCP, 2788 htonl(TCP_SIG_SPI), 0, 0); 2789 else 2790 sav = key_allocsa(AF_INET6, (caddr_t)&ip6->ip6_src, 2791 (caddr_t)&ip6->ip6_dst, IPPROTO_TCP, 2792 htonl(TCP_SIG_SPI), 0, 0); 2793 #endif 2794 2795 return (sav); /* freesav must be performed by caller */ 2796 } 2797 2798 int 2799 tcp_signature(struct mbuf *m, struct tcphdr *th, int thoff, 2800 struct secasvar *sav, char *sig) 2801 { 2802 MD5_CTX ctx; 2803 struct ip *ip; 2804 struct ipovly *ipovly; 2805 struct ip6_hdr *ip6; 2806 struct ippseudo ippseudo; 2807 struct ip6_hdr_pseudo ip6pseudo; 2808 struct tcphdr th0; 2809 int l, tcphdrlen; 2810 2811 if (sav == NULL) 2812 return (-1); 2813 2814 tcphdrlen = th->th_off * 4; 2815 2816 switch (mtod(m, struct ip *)->ip_v) { 2817 case 4: 2818 ip = mtod(m, struct ip *); 2819 ip6 = NULL; 2820 break; 2821 case 6: 2822 ip = NULL; 2823 ip6 = mtod(m, struct ip6_hdr *); 2824 break; 2825 default: 2826 return (-1); 2827 } 2828 2829 MD5Init(&ctx); 2830 2831 if (ip) { 2832 memset(&ippseudo, 0, sizeof(ippseudo)); 2833 ipovly = (struct ipovly *)ip; 2834 ippseudo.ippseudo_src = ipovly->ih_src; 2835 ippseudo.ippseudo_dst = ipovly->ih_dst; 2836 ippseudo.ippseudo_pad = 0; 2837 ippseudo.ippseudo_p = IPPROTO_TCP; 2838 ippseudo.ippseudo_len = htons(m->m_pkthdr.len - thoff); 2839 MD5Update(&ctx, (char *)&ippseudo, sizeof(ippseudo)); 2840 } else { 2841 memset(&ip6pseudo, 0, sizeof(ip6pseudo)); 2842 ip6pseudo.ip6ph_src = ip6->ip6_src; 2843 in6_clearscope(&ip6pseudo.ip6ph_src); 2844 ip6pseudo.ip6ph_dst = ip6->ip6_dst; 2845 in6_clearscope(&ip6pseudo.ip6ph_dst); 2846 ip6pseudo.ip6ph_len = htons(m->m_pkthdr.len - thoff); 2847 ip6pseudo.ip6ph_nxt = IPPROTO_TCP; 2848 MD5Update(&ctx, (char *)&ip6pseudo, sizeof(ip6pseudo)); 2849 } 2850 2851 th0 = *th; 2852 th0.th_sum = 0; 2853 MD5Update(&ctx, (char *)&th0, sizeof(th0)); 2854 2855 l = m->m_pkthdr.len - thoff - tcphdrlen; 2856 if (l > 0) 2857 m_apply(m, thoff + tcphdrlen, 2858 m->m_pkthdr.len - thoff - tcphdrlen, 2859 tcp_signature_apply, &ctx); 2860 2861 MD5Update(&ctx, _KEYBUF(sav->key_auth), _KEYLEN(sav->key_auth)); 2862 MD5Final(sig, &ctx); 2863 2864 return (0); 2865 } 2866 #endif 2867 2868 int 2869 tcp_dooptions(struct tcpcb *tp, u_char *cp, int cnt, struct tcphdr *th, 2870 struct mbuf *m, int toff, struct tcp_opt_info *oi) 2871 { 2872 u_int16_t mss; 2873 int opt, optlen = 0; 2874 #ifdef TCP_SIGNATURE 2875 caddr_t sigp = NULL; 2876 char sigbuf[TCP_SIGLEN]; 2877 struct secasvar *sav = NULL; 2878 #endif 2879 2880 for (; cp && cnt > 0; cnt -= optlen, cp += optlen) { 2881 opt = cp[0]; 2882 if (opt == TCPOPT_EOL) 2883 break; 2884 if (opt == TCPOPT_NOP) 2885 optlen = 1; 2886 else { 2887 if (cnt < 2) 2888 break; 2889 optlen = cp[1]; 2890 if (optlen < 2 || optlen > cnt) 2891 break; 2892 } 2893 switch (opt) { 2894 2895 default: 2896 continue; 2897 2898 case TCPOPT_MAXSEG: 2899 if (optlen != TCPOLEN_MAXSEG) 2900 continue; 2901 if (!(th->th_flags & TH_SYN)) 2902 continue; 2903 if (TCPS_HAVERCVDSYN(tp->t_state)) 2904 continue; 2905 bcopy(cp + 2, &mss, sizeof(mss)); 2906 oi->maxseg = ntohs(mss); 2907 break; 2908 2909 case TCPOPT_WINDOW: 2910 if (optlen != TCPOLEN_WINDOW) 2911 continue; 2912 if (!(th->th_flags & TH_SYN)) 2913 continue; 2914 if (TCPS_HAVERCVDSYN(tp->t_state)) 2915 continue; 2916 tp->t_flags |= TF_RCVD_SCALE; 2917 tp->requested_s_scale = cp[2]; 2918 if (tp->requested_s_scale > TCP_MAX_WINSHIFT) { 2919 #if 0 /*XXX*/ 2920 char *p; 2921 2922 if (ip) 2923 p = ntohl(ip->ip_src); 2924 #ifdef INET6 2925 else if (ip6) 2926 p = ip6_sprintf(&ip6->ip6_src); 2927 #endif 2928 else 2929 p = "(unknown)"; 2930 log(LOG_ERR, "TCP: invalid wscale %d from %s, " 2931 "assuming %d\n", 2932 tp->requested_s_scale, p, 2933 TCP_MAX_WINSHIFT); 2934 #else 2935 log(LOG_ERR, "TCP: invalid wscale %d, " 2936 "assuming %d\n", 2937 tp->requested_s_scale, 2938 TCP_MAX_WINSHIFT); 2939 #endif 2940 tp->requested_s_scale = TCP_MAX_WINSHIFT; 2941 } 2942 break; 2943 2944 case TCPOPT_TIMESTAMP: 2945 if (optlen != TCPOLEN_TIMESTAMP) 2946 continue; 2947 oi->ts_present = 1; 2948 bcopy(cp + 2, &oi->ts_val, sizeof(oi->ts_val)); 2949 NTOHL(oi->ts_val); 2950 bcopy(cp + 6, &oi->ts_ecr, sizeof(oi->ts_ecr)); 2951 NTOHL(oi->ts_ecr); 2952 2953 if (!(th->th_flags & TH_SYN)) 2954 continue; 2955 if (TCPS_HAVERCVDSYN(tp->t_state)) 2956 continue; 2957 /* 2958 * A timestamp received in a SYN makes 2959 * it ok to send timestamp requests and replies. 2960 */ 2961 tp->t_flags |= TF_RCVD_TSTMP; 2962 tp->ts_recent = oi->ts_val; 2963 tp->ts_recent_age = tcp_now; 2964 break; 2965 2966 case TCPOPT_SACK_PERMITTED: 2967 if (optlen != TCPOLEN_SACK_PERMITTED) 2968 continue; 2969 if (!(th->th_flags & TH_SYN)) 2970 continue; 2971 if (TCPS_HAVERCVDSYN(tp->t_state)) 2972 continue; 2973 if (tcp_do_sack) { 2974 tp->t_flags |= TF_SACK_PERMIT; 2975 tp->t_flags |= TF_WILL_SACK; 2976 } 2977 break; 2978 2979 case TCPOPT_SACK: 2980 tcp_sack_option(tp, th, cp, optlen); 2981 break; 2982 #ifdef TCP_SIGNATURE 2983 case TCPOPT_SIGNATURE: 2984 if (optlen != TCPOLEN_SIGNATURE) 2985 continue; 2986 if (sigp && bcmp(sigp, cp + 2, TCP_SIGLEN)) 2987 return (-1); 2988 2989 sigp = sigbuf; 2990 memcpy(sigbuf, cp + 2, TCP_SIGLEN); 2991 memset(cp + 2, 0, TCP_SIGLEN); 2992 tp->t_flags |= TF_SIGNATURE; 2993 break; 2994 #endif 2995 } 2996 } 2997 2998 #ifdef TCP_SIGNATURE 2999 if (tp->t_flags & TF_SIGNATURE) { 3000 3001 sav = tcp_signature_getsav(m, th); 3002 3003 if (sav == NULL && tp->t_state == TCPS_LISTEN) 3004 return (-1); 3005 } 3006 3007 if ((sigp ? TF_SIGNATURE : 0) ^ (tp->t_flags & TF_SIGNATURE)) { 3008 if (sav == NULL) 3009 return (-1); 3010 #ifdef FAST_IPSEC 3011 KEY_FREESAV(&sav); 3012 #else 3013 key_freesav(sav); 3014 #endif 3015 return (-1); 3016 } 3017 3018 if (sigp) { 3019 char sig[TCP_SIGLEN]; 3020 3021 TCP_FIELDS_TO_NET(th); 3022 if (tcp_signature(m, th, toff, sav, sig) < 0) { 3023 TCP_FIELDS_TO_HOST(th); 3024 if (sav == NULL) 3025 return (-1); 3026 #ifdef FAST_IPSEC 3027 KEY_FREESAV(&sav); 3028 #else 3029 key_freesav(sav); 3030 #endif 3031 return (-1); 3032 } 3033 TCP_FIELDS_TO_HOST(th); 3034 3035 if (bcmp(sig, sigp, TCP_SIGLEN)) { 3036 tcpstat.tcps_badsig++; 3037 if (sav == NULL) 3038 return (-1); 3039 #ifdef FAST_IPSEC 3040 KEY_FREESAV(&sav); 3041 #else 3042 key_freesav(sav); 3043 #endif 3044 return (-1); 3045 } else 3046 tcpstat.tcps_goodsig++; 3047 3048 key_sa_recordxfer(sav, m); 3049 #ifdef FAST_IPSEC 3050 KEY_FREESAV(&sav); 3051 #else 3052 key_freesav(sav); 3053 #endif 3054 } 3055 #endif 3056 3057 return (0); 3058 } 3059 3060 /* 3061 * Pull out of band byte out of a segment so 3062 * it doesn't appear in the user's data queue. 3063 * It is still reflected in the segment length for 3064 * sequencing purposes. 3065 */ 3066 void 3067 tcp_pulloutofband(struct socket *so, struct tcphdr *th, 3068 struct mbuf *m, int off) 3069 { 3070 int cnt = off + th->th_urp - 1; 3071 3072 while (cnt >= 0) { 3073 if (m->m_len > cnt) { 3074 char *cp = mtod(m, caddr_t) + cnt; 3075 struct tcpcb *tp = sototcpcb(so); 3076 3077 tp->t_iobc = *cp; 3078 tp->t_oobflags |= TCPOOB_HAVEDATA; 3079 bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); 3080 m->m_len--; 3081 return; 3082 } 3083 cnt -= m->m_len; 3084 m = m->m_next; 3085 if (m == 0) 3086 break; 3087 } 3088 panic("tcp_pulloutofband"); 3089 } 3090 3091 /* 3092 * Collect new round-trip time estimate 3093 * and update averages and current timeout. 3094 */ 3095 void 3096 tcp_xmit_timer(struct tcpcb *tp, uint32_t rtt) 3097 { 3098 int32_t delta; 3099 3100 tcpstat.tcps_rttupdated++; 3101 if (tp->t_srtt != 0) { 3102 /* 3103 * srtt is stored as fixed point with 3 bits after the 3104 * binary point (i.e., scaled by 8). The following magic 3105 * is equivalent to the smoothing algorithm in rfc793 with 3106 * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed 3107 * point). Adjust rtt to origin 0. 3108 */ 3109 delta = (rtt << 2) - (tp->t_srtt >> TCP_RTT_SHIFT); 3110 if ((tp->t_srtt += delta) <= 0) 3111 tp->t_srtt = 1 << 2; 3112 /* 3113 * We accumulate a smoothed rtt variance (actually, a 3114 * smoothed mean difference), then set the retransmit 3115 * timer to smoothed rtt + 4 times the smoothed variance. 3116 * rttvar is stored as fixed point with 2 bits after the 3117 * binary point (scaled by 4). The following is 3118 * equivalent to rfc793 smoothing with an alpha of .75 3119 * (rttvar = rttvar*3/4 + |delta| / 4). This replaces 3120 * rfc793's wired-in beta. 3121 */ 3122 if (delta < 0) 3123 delta = -delta; 3124 delta -= (tp->t_rttvar >> TCP_RTTVAR_SHIFT); 3125 if ((tp->t_rttvar += delta) <= 0) 3126 tp->t_rttvar = 1 << 2; 3127 } else { 3128 /* 3129 * No rtt measurement yet - use the unsmoothed rtt. 3130 * Set the variance to half the rtt (so our first 3131 * retransmit happens at 3*rtt). 3132 */ 3133 tp->t_srtt = rtt << (TCP_RTT_SHIFT + 2); 3134 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT + 2 - 1); 3135 } 3136 tp->t_rtttime = 0; 3137 tp->t_rxtshift = 0; 3138 3139 /* 3140 * the retransmit should happen at rtt + 4 * rttvar. 3141 * Because of the way we do the smoothing, srtt and rttvar 3142 * will each average +1/2 tick of bias. When we compute 3143 * the retransmit timer, we want 1/2 tick of rounding and 3144 * 1 extra tick because of +-1/2 tick uncertainty in the 3145 * firing of the timer. The bias will give us exactly the 3146 * 1.5 tick we need. But, because the bias is 3147 * statistical, we have to test that we don't drop below 3148 * the minimum feasible timer (which is 2 ticks). 3149 */ 3150 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), 3151 max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX); 3152 3153 /* 3154 * We received an ack for a packet that wasn't retransmitted; 3155 * it is probably safe to discard any error indications we've 3156 * received recently. This isn't quite right, but close enough 3157 * for now (a route might have failed after we sent a segment, 3158 * and the return path might not be symmetrical). 3159 */ 3160 tp->t_softerror = 0; 3161 } 3162 3163 void 3164 tcp_reno_newack(struct tcpcb *tp, struct tcphdr *th) 3165 { 3166 if (tp->t_partialacks < 0) { 3167 /* 3168 * We were not in fast recovery. Reset the duplicate ack 3169 * counter. 3170 */ 3171 tp->t_dupacks = 0; 3172 } else { 3173 /* 3174 * Clamp the congestion window to the crossover point and 3175 * exit fast recovery. 3176 */ 3177 if (tp->snd_cwnd > tp->snd_ssthresh) 3178 tp->snd_cwnd = tp->snd_ssthresh; 3179 tp->t_partialacks = -1; 3180 tp->t_dupacks = 0; 3181 } 3182 } 3183 3184 /* 3185 * Implement the NewReno response to a new ack, checking for partial acks in 3186 * fast recovery. 3187 */ 3188 void 3189 tcp_newreno_newack(struct tcpcb *tp, struct tcphdr *th) 3190 { 3191 if (tp->t_partialacks < 0) { 3192 /* 3193 * We were not in fast recovery. Reset the duplicate ack 3194 * counter. 3195 */ 3196 tp->t_dupacks = 0; 3197 } else if (SEQ_LT(th->th_ack, tp->snd_recover)) { 3198 /* 3199 * This is a partial ack. Retransmit the first unacknowledged 3200 * segment and deflate the congestion window by the amount of 3201 * acknowledged data. Do not exit fast recovery. 3202 */ 3203 tcp_seq onxt = tp->snd_nxt; 3204 u_long ocwnd = tp->snd_cwnd; 3205 3206 /* 3207 * snd_una has not yet been updated and the socket's send 3208 * buffer has not yet drained off the ACK'd data, so we 3209 * have to leave snd_una as it was to get the correct data 3210 * offset in tcp_output(). 3211 */ 3212 if (++tp->t_partialacks == 1) 3213 TCP_TIMER_DISARM(tp, TCPT_REXMT); 3214 tp->t_rtttime = 0; 3215 tp->snd_nxt = th->th_ack; 3216 /* 3217 * Set snd_cwnd to one segment beyond ACK'd offset. snd_una 3218 * is not yet updated when we're called. 3219 */ 3220 tp->snd_cwnd = tp->t_segsz + (th->th_ack - tp->snd_una); 3221 (void) tcp_output(tp); 3222 tp->snd_cwnd = ocwnd; 3223 if (SEQ_GT(onxt, tp->snd_nxt)) 3224 tp->snd_nxt = onxt; 3225 /* 3226 * Partial window deflation. Relies on fact that tp->snd_una 3227 * not updated yet. 3228 */ 3229 tp->snd_cwnd -= (th->th_ack - tp->snd_una - tp->t_segsz); 3230 } else { 3231 /* 3232 * Complete ack. Inflate the congestion window to ssthresh 3233 * and exit fast recovery. 3234 * 3235 * Window inflation should have left us with approx. 3236 * snd_ssthresh outstanding data. But in case we 3237 * would be inclined to send a burst, better to do 3238 * it via the slow start mechanism. 3239 */ 3240 if (SEQ_SUB(tp->snd_max, th->th_ack) < tp->snd_ssthresh) 3241 tp->snd_cwnd = SEQ_SUB(tp->snd_max, th->th_ack) 3242 + tp->t_segsz; 3243 else 3244 tp->snd_cwnd = tp->snd_ssthresh; 3245 tp->t_partialacks = -1; 3246 tp->t_dupacks = 0; 3247 } 3248 } 3249 3250 3251 /* 3252 * TCP compressed state engine. Currently used to hold compressed 3253 * state for SYN_RECEIVED. 3254 */ 3255 3256 u_long syn_cache_count; 3257 u_int32_t syn_hash1, syn_hash2; 3258 3259 #define SYN_HASH(sa, sp, dp) \ 3260 ((((sa)->s_addr^syn_hash1)*(((((u_int32_t)(dp))<<16) + \ 3261 ((u_int32_t)(sp)))^syn_hash2))) 3262 #ifndef INET6 3263 #define SYN_HASHALL(hash, src, dst) \ 3264 do { \ 3265 hash = SYN_HASH(&((const struct sockaddr_in *)(src))->sin_addr, \ 3266 ((const struct sockaddr_in *)(src))->sin_port, \ 3267 ((const struct sockaddr_in *)(dst))->sin_port); \ 3268 } while (/*CONSTCOND*/ 0) 3269 #else 3270 #define SYN_HASH6(sa, sp, dp) \ 3271 ((((sa)->s6_addr32[0] ^ (sa)->s6_addr32[3] ^ syn_hash1) * \ 3272 (((((u_int32_t)(dp))<<16) + ((u_int32_t)(sp)))^syn_hash2)) \ 3273 & 0x7fffffff) 3274 3275 #define SYN_HASHALL(hash, src, dst) \ 3276 do { \ 3277 switch ((src)->sa_family) { \ 3278 case AF_INET: \ 3279 hash = SYN_HASH(&((const struct sockaddr_in *)(src))->sin_addr, \ 3280 ((const struct sockaddr_in *)(src))->sin_port, \ 3281 ((const struct sockaddr_in *)(dst))->sin_port); \ 3282 break; \ 3283 case AF_INET6: \ 3284 hash = SYN_HASH6(&((const struct sockaddr_in6 *)(src))->sin6_addr, \ 3285 ((const struct sockaddr_in6 *)(src))->sin6_port, \ 3286 ((const struct sockaddr_in6 *)(dst))->sin6_port); \ 3287 break; \ 3288 default: \ 3289 hash = 0; \ 3290 } \ 3291 } while (/*CONSTCOND*/0) 3292 #endif /* INET6 */ 3293 3294 #define SYN_CACHE_RM(sc) \ 3295 do { \ 3296 TAILQ_REMOVE(&tcp_syn_cache[(sc)->sc_bucketidx].sch_bucket, \ 3297 (sc), sc_bucketq); \ 3298 (sc)->sc_tp = NULL; \ 3299 LIST_REMOVE((sc), sc_tpq); \ 3300 tcp_syn_cache[(sc)->sc_bucketidx].sch_length--; \ 3301 callout_stop(&(sc)->sc_timer); \ 3302 syn_cache_count--; \ 3303 } while (/*CONSTCOND*/0) 3304 3305 #define SYN_CACHE_PUT(sc) \ 3306 do { \ 3307 if ((sc)->sc_ipopts) \ 3308 (void) m_free((sc)->sc_ipopts); \ 3309 if ((sc)->sc_route4.ro_rt != NULL) \ 3310 RTFREE((sc)->sc_route4.ro_rt); \ 3311 if (callout_invoking(&(sc)->sc_timer)) \ 3312 (sc)->sc_flags |= SCF_DEAD; \ 3313 else \ 3314 pool_put(&syn_cache_pool, (sc)); \ 3315 } while (/*CONSTCOND*/0) 3316 3317 POOL_INIT(syn_cache_pool, sizeof(struct syn_cache), 0, 0, 0, "synpl", NULL); 3318 3319 /* 3320 * We don't estimate RTT with SYNs, so each packet starts with the default 3321 * RTT and each timer step has a fixed timeout value. 3322 */ 3323 #define SYN_CACHE_TIMER_ARM(sc) \ 3324 do { \ 3325 TCPT_RANGESET((sc)->sc_rxtcur, \ 3326 TCPTV_SRTTDFLT * tcp_backoff[(sc)->sc_rxtshift], TCPTV_MIN, \ 3327 TCPTV_REXMTMAX); \ 3328 callout_reset(&(sc)->sc_timer, \ 3329 (sc)->sc_rxtcur * (hz / PR_SLOWHZ), syn_cache_timer, (sc)); \ 3330 } while (/*CONSTCOND*/0) 3331 3332 #define SYN_CACHE_TIMESTAMP(sc) (tcp_now - (sc)->sc_timebase) 3333 3334 void 3335 syn_cache_init(void) 3336 { 3337 int i; 3338 3339 /* Initialize the hash buckets. */ 3340 for (i = 0; i < tcp_syn_cache_size; i++) 3341 TAILQ_INIT(&tcp_syn_cache[i].sch_bucket); 3342 } 3343 3344 void 3345 syn_cache_insert(struct syn_cache *sc, struct tcpcb *tp) 3346 { 3347 struct syn_cache_head *scp; 3348 struct syn_cache *sc2; 3349 int s; 3350 3351 /* 3352 * If there are no entries in the hash table, reinitialize 3353 * the hash secrets. 3354 */ 3355 if (syn_cache_count == 0) { 3356 syn_hash1 = arc4random(); 3357 syn_hash2 = arc4random(); 3358 } 3359 3360 SYN_HASHALL(sc->sc_hash, &sc->sc_src.sa, &sc->sc_dst.sa); 3361 sc->sc_bucketidx = sc->sc_hash % tcp_syn_cache_size; 3362 scp = &tcp_syn_cache[sc->sc_bucketidx]; 3363 3364 /* 3365 * Make sure that we don't overflow the per-bucket 3366 * limit or the total cache size limit. 3367 */ 3368 s = splsoftnet(); 3369 if (scp->sch_length >= tcp_syn_bucket_limit) { 3370 tcpstat.tcps_sc_bucketoverflow++; 3371 /* 3372 * The bucket is full. Toss the oldest element in the 3373 * bucket. This will be the first entry in the bucket. 3374 */ 3375 sc2 = TAILQ_FIRST(&scp->sch_bucket); 3376 #ifdef DIAGNOSTIC 3377 /* 3378 * This should never happen; we should always find an 3379 * entry in our bucket. 3380 */ 3381 if (sc2 == NULL) 3382 panic("syn_cache_insert: bucketoverflow: impossible"); 3383 #endif 3384 SYN_CACHE_RM(sc2); 3385 SYN_CACHE_PUT(sc2); 3386 } else if (syn_cache_count >= tcp_syn_cache_limit) { 3387 struct syn_cache_head *scp2, *sce; 3388 3389 tcpstat.tcps_sc_overflowed++; 3390 /* 3391 * The cache is full. Toss the oldest entry in the 3392 * first non-empty bucket we can find. 3393 * 3394 * XXX We would really like to toss the oldest 3395 * entry in the cache, but we hope that this 3396 * condition doesn't happen very often. 3397 */ 3398 scp2 = scp; 3399 if (TAILQ_EMPTY(&scp2->sch_bucket)) { 3400 sce = &tcp_syn_cache[tcp_syn_cache_size]; 3401 for (++scp2; scp2 != scp; scp2++) { 3402 if (scp2 >= sce) 3403 scp2 = &tcp_syn_cache[0]; 3404 if (! TAILQ_EMPTY(&scp2->sch_bucket)) 3405 break; 3406 } 3407 #ifdef DIAGNOSTIC 3408 /* 3409 * This should never happen; we should always find a 3410 * non-empty bucket. 3411 */ 3412 if (scp2 == scp) 3413 panic("syn_cache_insert: cacheoverflow: " 3414 "impossible"); 3415 #endif 3416 } 3417 sc2 = TAILQ_FIRST(&scp2->sch_bucket); 3418 SYN_CACHE_RM(sc2); 3419 SYN_CACHE_PUT(sc2); 3420 } 3421 3422 /* 3423 * Initialize the entry's timer. 3424 */ 3425 sc->sc_rxttot = 0; 3426 sc->sc_rxtshift = 0; 3427 SYN_CACHE_TIMER_ARM(sc); 3428 3429 /* Link it from tcpcb entry */ 3430 LIST_INSERT_HEAD(&tp->t_sc, sc, sc_tpq); 3431 3432 /* Put it into the bucket. */ 3433 TAILQ_INSERT_TAIL(&scp->sch_bucket, sc, sc_bucketq); 3434 scp->sch_length++; 3435 syn_cache_count++; 3436 3437 tcpstat.tcps_sc_added++; 3438 splx(s); 3439 } 3440 3441 /* 3442 * Walk the timer queues, looking for SYN,ACKs that need to be retransmitted. 3443 * If we have retransmitted an entry the maximum number of times, expire 3444 * that entry. 3445 */ 3446 void 3447 syn_cache_timer(void *arg) 3448 { 3449 struct syn_cache *sc = arg; 3450 int s; 3451 3452 s = splsoftnet(); 3453 callout_ack(&sc->sc_timer); 3454 3455 if (__predict_false(sc->sc_flags & SCF_DEAD)) { 3456 tcpstat.tcps_sc_delayed_free++; 3457 pool_put(&syn_cache_pool, sc); 3458 splx(s); 3459 return; 3460 } 3461 3462 if (__predict_false(sc->sc_rxtshift == TCP_MAXRXTSHIFT)) { 3463 /* Drop it -- too many retransmissions. */ 3464 goto dropit; 3465 } 3466 3467 /* 3468 * Compute the total amount of time this entry has 3469 * been on a queue. If this entry has been on longer 3470 * than the keep alive timer would allow, expire it. 3471 */ 3472 sc->sc_rxttot += sc->sc_rxtcur; 3473 if (sc->sc_rxttot >= TCPTV_KEEP_INIT) 3474 goto dropit; 3475 3476 tcpstat.tcps_sc_retransmitted++; 3477 (void) syn_cache_respond(sc, NULL); 3478 3479 /* Advance the timer back-off. */ 3480 sc->sc_rxtshift++; 3481 SYN_CACHE_TIMER_ARM(sc); 3482 3483 splx(s); 3484 return; 3485 3486 dropit: 3487 tcpstat.tcps_sc_timed_out++; 3488 SYN_CACHE_RM(sc); 3489 SYN_CACHE_PUT(sc); 3490 splx(s); 3491 } 3492 3493 /* 3494 * Remove syn cache created by the specified tcb entry, 3495 * because this does not make sense to keep them 3496 * (if there's no tcb entry, syn cache entry will never be used) 3497 */ 3498 void 3499 syn_cache_cleanup(struct tcpcb *tp) 3500 { 3501 struct syn_cache *sc, *nsc; 3502 int s; 3503 3504 s = splsoftnet(); 3505 3506 for (sc = LIST_FIRST(&tp->t_sc); sc != NULL; sc = nsc) { 3507 nsc = LIST_NEXT(sc, sc_tpq); 3508 3509 #ifdef DIAGNOSTIC 3510 if (sc->sc_tp != tp) 3511 panic("invalid sc_tp in syn_cache_cleanup"); 3512 #endif 3513 SYN_CACHE_RM(sc); 3514 SYN_CACHE_PUT(sc); 3515 } 3516 /* just for safety */ 3517 LIST_INIT(&tp->t_sc); 3518 3519 splx(s); 3520 } 3521 3522 /* 3523 * Find an entry in the syn cache. 3524 */ 3525 struct syn_cache * 3526 syn_cache_lookup(const struct sockaddr *src, const struct sockaddr *dst, 3527 struct syn_cache_head **headp) 3528 { 3529 struct syn_cache *sc; 3530 struct syn_cache_head *scp; 3531 u_int32_t hash; 3532 int s; 3533 3534 SYN_HASHALL(hash, src, dst); 3535 3536 scp = &tcp_syn_cache[hash % tcp_syn_cache_size]; 3537 *headp = scp; 3538 s = splsoftnet(); 3539 for (sc = TAILQ_FIRST(&scp->sch_bucket); sc != NULL; 3540 sc = TAILQ_NEXT(sc, sc_bucketq)) { 3541 if (sc->sc_hash != hash) 3542 continue; 3543 if (!bcmp(&sc->sc_src, src, src->sa_len) && 3544 !bcmp(&sc->sc_dst, dst, dst->sa_len)) { 3545 splx(s); 3546 return (sc); 3547 } 3548 } 3549 splx(s); 3550 return (NULL); 3551 } 3552 3553 /* 3554 * This function gets called when we receive an ACK for a 3555 * socket in the LISTEN state. We look up the connection 3556 * in the syn cache, and if its there, we pull it out of 3557 * the cache and turn it into a full-blown connection in 3558 * the SYN-RECEIVED state. 3559 * 3560 * The return values may not be immediately obvious, and their effects 3561 * can be subtle, so here they are: 3562 * 3563 * NULL SYN was not found in cache; caller should drop the 3564 * packet and send an RST. 3565 * 3566 * -1 We were unable to create the new connection, and are 3567 * aborting it. An ACK,RST is being sent to the peer 3568 * (unless we got screwey sequence numbners; see below), 3569 * because the 3-way handshake has been completed. Caller 3570 * should not free the mbuf, since we may be using it. If 3571 * we are not, we will free it. 3572 * 3573 * Otherwise, the return value is a pointer to the new socket 3574 * associated with the connection. 3575 */ 3576 struct socket * 3577 syn_cache_get(struct sockaddr *src, struct sockaddr *dst, 3578 struct tcphdr *th, unsigned int hlen, unsigned int tlen, 3579 struct socket *so, struct mbuf *m) 3580 { 3581 struct syn_cache *sc; 3582 struct syn_cache_head *scp; 3583 struct inpcb *inp = NULL; 3584 #ifdef INET6 3585 struct in6pcb *in6p = NULL; 3586 #endif 3587 struct tcpcb *tp = 0; 3588 struct mbuf *am; 3589 int s; 3590 struct socket *oso; 3591 3592 s = splsoftnet(); 3593 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 3594 splx(s); 3595 return (NULL); 3596 } 3597 3598 /* 3599 * Verify the sequence and ack numbers. Try getting the correct 3600 * response again. 3601 */ 3602 if ((th->th_ack != sc->sc_iss + 1) || 3603 SEQ_LEQ(th->th_seq, sc->sc_irs) || 3604 SEQ_GT(th->th_seq, sc->sc_irs + 1 + sc->sc_win)) { 3605 (void) syn_cache_respond(sc, m); 3606 splx(s); 3607 return ((struct socket *)(-1)); 3608 } 3609 3610 /* Remove this cache entry */ 3611 SYN_CACHE_RM(sc); 3612 splx(s); 3613 3614 /* 3615 * Ok, create the full blown connection, and set things up 3616 * as they would have been set up if we had created the 3617 * connection when the SYN arrived. If we can't create 3618 * the connection, abort it. 3619 */ 3620 /* 3621 * inp still has the OLD in_pcb stuff, set the 3622 * v6-related flags on the new guy, too. This is 3623 * done particularly for the case where an AF_INET6 3624 * socket is bound only to a port, and a v4 connection 3625 * comes in on that port. 3626 * we also copy the flowinfo from the original pcb 3627 * to the new one. 3628 */ 3629 oso = so; 3630 so = sonewconn(so, SS_ISCONNECTED); 3631 if (so == NULL) 3632 goto resetandabort; 3633 3634 switch (so->so_proto->pr_domain->dom_family) { 3635 #ifdef INET 3636 case AF_INET: 3637 inp = sotoinpcb(so); 3638 break; 3639 #endif 3640 #ifdef INET6 3641 case AF_INET6: 3642 in6p = sotoin6pcb(so); 3643 break; 3644 #endif 3645 } 3646 switch (src->sa_family) { 3647 #ifdef INET 3648 case AF_INET: 3649 if (inp) { 3650 inp->inp_laddr = ((struct sockaddr_in *)dst)->sin_addr; 3651 inp->inp_lport = ((struct sockaddr_in *)dst)->sin_port; 3652 inp->inp_options = ip_srcroute(); 3653 in_pcbstate(inp, INP_BOUND); 3654 if (inp->inp_options == NULL) { 3655 inp->inp_options = sc->sc_ipopts; 3656 sc->sc_ipopts = NULL; 3657 } 3658 } 3659 #ifdef INET6 3660 else if (in6p) { 3661 /* IPv4 packet to AF_INET6 socket */ 3662 bzero(&in6p->in6p_laddr, sizeof(in6p->in6p_laddr)); 3663 in6p->in6p_laddr.s6_addr16[5] = htons(0xffff); 3664 bcopy(&((struct sockaddr_in *)dst)->sin_addr, 3665 &in6p->in6p_laddr.s6_addr32[3], 3666 sizeof(((struct sockaddr_in *)dst)->sin_addr)); 3667 in6p->in6p_lport = ((struct sockaddr_in *)dst)->sin_port; 3668 in6totcpcb(in6p)->t_family = AF_INET; 3669 if (sotoin6pcb(oso)->in6p_flags & IN6P_IPV6_V6ONLY) 3670 in6p->in6p_flags |= IN6P_IPV6_V6ONLY; 3671 else 3672 in6p->in6p_flags &= ~IN6P_IPV6_V6ONLY; 3673 in6_pcbstate(in6p, IN6P_BOUND); 3674 } 3675 #endif 3676 break; 3677 #endif 3678 #ifdef INET6 3679 case AF_INET6: 3680 if (in6p) { 3681 in6p->in6p_laddr = ((struct sockaddr_in6 *)dst)->sin6_addr; 3682 in6p->in6p_lport = ((struct sockaddr_in6 *)dst)->sin6_port; 3683 in6_pcbstate(in6p, IN6P_BOUND); 3684 } 3685 break; 3686 #endif 3687 } 3688 #ifdef INET6 3689 if (in6p && in6totcpcb(in6p)->t_family == AF_INET6 && sotoinpcb(oso)) { 3690 struct in6pcb *oin6p = sotoin6pcb(oso); 3691 /* inherit socket options from the listening socket */ 3692 in6p->in6p_flags |= (oin6p->in6p_flags & IN6P_CONTROLOPTS); 3693 if (in6p->in6p_flags & IN6P_CONTROLOPTS) { 3694 m_freem(in6p->in6p_options); 3695 in6p->in6p_options = 0; 3696 } 3697 ip6_savecontrol(in6p, &in6p->in6p_options, 3698 mtod(m, struct ip6_hdr *), m); 3699 } 3700 #endif 3701 3702 #if defined(IPSEC) || defined(FAST_IPSEC) 3703 /* 3704 * we make a copy of policy, instead of sharing the policy, 3705 * for better behavior in terms of SA lookup and dead SA removal. 3706 */ 3707 if (inp) { 3708 /* copy old policy into new socket's */ 3709 if (ipsec_copy_pcbpolicy(sotoinpcb(oso)->inp_sp, inp->inp_sp)) 3710 printf("tcp_input: could not copy policy\n"); 3711 } 3712 #ifdef INET6 3713 else if (in6p) { 3714 /* copy old policy into new socket's */ 3715 if (ipsec_copy_pcbpolicy(sotoin6pcb(oso)->in6p_sp, 3716 in6p->in6p_sp)) 3717 printf("tcp_input: could not copy policy\n"); 3718 } 3719 #endif 3720 #endif 3721 3722 /* 3723 * Give the new socket our cached route reference. 3724 */ 3725 if (inp) 3726 inp->inp_route = sc->sc_route4; /* struct assignment */ 3727 #ifdef INET6 3728 else 3729 in6p->in6p_route = sc->sc_route6; 3730 #endif 3731 sc->sc_route4.ro_rt = NULL; 3732 3733 am = m_get(M_DONTWAIT, MT_SONAME); /* XXX */ 3734 if (am == NULL) 3735 goto resetandabort; 3736 MCLAIM(am, &tcp_mowner); 3737 am->m_len = src->sa_len; 3738 bcopy(src, mtod(am, caddr_t), src->sa_len); 3739 if (inp) { 3740 if (in_pcbconnect(inp, am, NULL)) { 3741 (void) m_free(am); 3742 goto resetandabort; 3743 } 3744 } 3745 #ifdef INET6 3746 else if (in6p) { 3747 if (src->sa_family == AF_INET) { 3748 /* IPv4 packet to AF_INET6 socket */ 3749 struct sockaddr_in6 *sin6; 3750 sin6 = mtod(am, struct sockaddr_in6 *); 3751 am->m_len = sizeof(*sin6); 3752 bzero(sin6, sizeof(*sin6)); 3753 sin6->sin6_family = AF_INET6; 3754 sin6->sin6_len = sizeof(*sin6); 3755 sin6->sin6_port = ((struct sockaddr_in *)src)->sin_port; 3756 sin6->sin6_addr.s6_addr16[5] = htons(0xffff); 3757 bcopy(&((struct sockaddr_in *)src)->sin_addr, 3758 &sin6->sin6_addr.s6_addr32[3], 3759 sizeof(sin6->sin6_addr.s6_addr32[3])); 3760 } 3761 if (in6_pcbconnect(in6p, am, NULL)) { 3762 (void) m_free(am); 3763 goto resetandabort; 3764 } 3765 } 3766 #endif 3767 else { 3768 (void) m_free(am); 3769 goto resetandabort; 3770 } 3771 (void) m_free(am); 3772 3773 if (inp) 3774 tp = intotcpcb(inp); 3775 #ifdef INET6 3776 else if (in6p) 3777 tp = in6totcpcb(in6p); 3778 #endif 3779 else 3780 tp = NULL; 3781 tp->t_flags = sototcpcb(oso)->t_flags & TF_NODELAY; 3782 if (sc->sc_request_r_scale != 15) { 3783 tp->requested_s_scale = sc->sc_requested_s_scale; 3784 tp->request_r_scale = sc->sc_request_r_scale; 3785 tp->snd_scale = sc->sc_requested_s_scale; 3786 tp->rcv_scale = sc->sc_request_r_scale; 3787 tp->t_flags |= TF_REQ_SCALE|TF_RCVD_SCALE; 3788 } 3789 if (sc->sc_flags & SCF_TIMESTAMP) 3790 tp->t_flags |= TF_REQ_TSTMP|TF_RCVD_TSTMP; 3791 tp->ts_timebase = sc->sc_timebase; 3792 3793 tp->t_template = tcp_template(tp); 3794 if (tp->t_template == 0) { 3795 tp = tcp_drop(tp, ENOBUFS); /* destroys socket */ 3796 so = NULL; 3797 m_freem(m); 3798 goto abort; 3799 } 3800 3801 tp->iss = sc->sc_iss; 3802 tp->irs = sc->sc_irs; 3803 tcp_sendseqinit(tp); 3804 tcp_rcvseqinit(tp); 3805 tp->t_state = TCPS_SYN_RECEIVED; 3806 TCP_TIMER_ARM(tp, TCPT_KEEP, TCPTV_KEEP_INIT); 3807 tcpstat.tcps_accepts++; 3808 3809 if ((sc->sc_flags & SCF_SACK_PERMIT) && tcp_do_sack) 3810 tp->t_flags |= TF_WILL_SACK; 3811 3812 #ifdef TCP_SIGNATURE 3813 if (sc->sc_flags & SCF_SIGNATURE) 3814 tp->t_flags |= TF_SIGNATURE; 3815 #endif 3816 3817 /* Initialize tp->t_ourmss before we deal with the peer's! */ 3818 tp->t_ourmss = sc->sc_ourmaxseg; 3819 tcp_mss_from_peer(tp, sc->sc_peermaxseg); 3820 3821 /* 3822 * Initialize the initial congestion window. If we 3823 * had to retransmit the SYN,ACK, we must initialize cwnd 3824 * to 1 segment (i.e. the Loss Window). 3825 */ 3826 if (sc->sc_rxtshift) 3827 tp->snd_cwnd = tp->t_peermss; 3828 else { 3829 int ss = tcp_init_win; 3830 #ifdef INET 3831 if (inp != NULL && in_localaddr(inp->inp_faddr)) 3832 ss = tcp_init_win_local; 3833 #endif 3834 #ifdef INET6 3835 if (in6p != NULL && in6_localaddr(&in6p->in6p_faddr)) 3836 ss = tcp_init_win_local; 3837 #endif 3838 tp->snd_cwnd = TCP_INITIAL_WINDOW(ss, tp->t_peermss); 3839 } 3840 3841 tcp_rmx_rtt(tp); 3842 tp->snd_wl1 = sc->sc_irs; 3843 tp->rcv_up = sc->sc_irs + 1; 3844 3845 /* 3846 * This is what whould have happened in tcp_output() when 3847 * the SYN,ACK was sent. 3848 */ 3849 tp->snd_up = tp->snd_una; 3850 tp->snd_max = tp->snd_nxt = tp->iss+1; 3851 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 3852 if (sc->sc_win > 0 && SEQ_GT(tp->rcv_nxt + sc->sc_win, tp->rcv_adv)) 3853 tp->rcv_adv = tp->rcv_nxt + sc->sc_win; 3854 tp->last_ack_sent = tp->rcv_nxt; 3855 tp->t_partialacks = -1; 3856 tp->t_dupacks = 0; 3857 3858 tcpstat.tcps_sc_completed++; 3859 SYN_CACHE_PUT(sc); 3860 return (so); 3861 3862 resetandabort: 3863 (void)tcp_respond(NULL, m, m, th, (tcp_seq)0, th->th_ack, TH_RST); 3864 abort: 3865 if (so != NULL) 3866 (void) soabort(so); 3867 SYN_CACHE_PUT(sc); 3868 tcpstat.tcps_sc_aborted++; 3869 return ((struct socket *)(-1)); 3870 } 3871 3872 /* 3873 * This function is called when we get a RST for a 3874 * non-existent connection, so that we can see if the 3875 * connection is in the syn cache. If it is, zap it. 3876 */ 3877 3878 void 3879 syn_cache_reset(struct sockaddr *src, struct sockaddr *dst, struct tcphdr *th) 3880 { 3881 struct syn_cache *sc; 3882 struct syn_cache_head *scp; 3883 int s = splsoftnet(); 3884 3885 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 3886 splx(s); 3887 return; 3888 } 3889 if (SEQ_LT(th->th_seq, sc->sc_irs) || 3890 SEQ_GT(th->th_seq, sc->sc_irs+1)) { 3891 splx(s); 3892 return; 3893 } 3894 SYN_CACHE_RM(sc); 3895 splx(s); 3896 tcpstat.tcps_sc_reset++; 3897 SYN_CACHE_PUT(sc); 3898 } 3899 3900 void 3901 syn_cache_unreach(const struct sockaddr *src, const struct sockaddr *dst, 3902 struct tcphdr *th) 3903 { 3904 struct syn_cache *sc; 3905 struct syn_cache_head *scp; 3906 int s; 3907 3908 s = splsoftnet(); 3909 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 3910 splx(s); 3911 return; 3912 } 3913 /* If the sequence number != sc_iss, then it's a bogus ICMP msg */ 3914 if (ntohl (th->th_seq) != sc->sc_iss) { 3915 splx(s); 3916 return; 3917 } 3918 3919 /* 3920 * If we've retransmitted 3 times and this is our second error, 3921 * we remove the entry. Otherwise, we allow it to continue on. 3922 * This prevents us from incorrectly nuking an entry during a 3923 * spurious network outage. 3924 * 3925 * See tcp_notify(). 3926 */ 3927 if ((sc->sc_flags & SCF_UNREACH) == 0 || sc->sc_rxtshift < 3) { 3928 sc->sc_flags |= SCF_UNREACH; 3929 splx(s); 3930 return; 3931 } 3932 3933 SYN_CACHE_RM(sc); 3934 splx(s); 3935 tcpstat.tcps_sc_unreach++; 3936 SYN_CACHE_PUT(sc); 3937 } 3938 3939 /* 3940 * Given a LISTEN socket and an inbound SYN request, add 3941 * this to the syn cache, and send back a segment: 3942 * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK> 3943 * to the source. 3944 * 3945 * IMPORTANT NOTE: We do _NOT_ ACK data that might accompany the SYN. 3946 * Doing so would require that we hold onto the data and deliver it 3947 * to the application. However, if we are the target of a SYN-flood 3948 * DoS attack, an attacker could send data which would eventually 3949 * consume all available buffer space if it were ACKed. By not ACKing 3950 * the data, we avoid this DoS scenario. 3951 */ 3952 3953 int 3954 syn_cache_add(struct sockaddr *src, struct sockaddr *dst, struct tcphdr *th, 3955 unsigned int hlen, struct socket *so, struct mbuf *m, u_char *optp, 3956 int optlen, struct tcp_opt_info *oi) 3957 { 3958 struct tcpcb tb, *tp; 3959 long win; 3960 struct syn_cache *sc; 3961 struct syn_cache_head *scp; 3962 struct mbuf *ipopts; 3963 struct tcp_opt_info opti; 3964 3965 tp = sototcpcb(so); 3966 3967 bzero(&opti, sizeof(opti)); 3968 3969 /* 3970 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN 3971 * 3972 * Note this check is performed in tcp_input() very early on. 3973 */ 3974 3975 /* 3976 * Initialize some local state. 3977 */ 3978 win = sbspace(&so->so_rcv); 3979 if (win > TCP_MAXWIN) 3980 win = TCP_MAXWIN; 3981 3982 switch (src->sa_family) { 3983 #ifdef INET 3984 case AF_INET: 3985 /* 3986 * Remember the IP options, if any. 3987 */ 3988 ipopts = ip_srcroute(); 3989 break; 3990 #endif 3991 default: 3992 ipopts = NULL; 3993 } 3994 3995 #ifdef TCP_SIGNATURE 3996 if (optp || (tp->t_flags & TF_SIGNATURE)) 3997 #else 3998 if (optp) 3999 #endif 4000 { 4001 tb.t_flags = tcp_do_rfc1323 ? (TF_REQ_SCALE|TF_REQ_TSTMP) : 0; 4002 #ifdef TCP_SIGNATURE 4003 tb.t_flags |= (tp->t_flags & TF_SIGNATURE); 4004 #endif 4005 tb.t_state = TCPS_LISTEN; 4006 if (tcp_dooptions(&tb, optp, optlen, th, m, m->m_pkthdr.len - 4007 sizeof(struct tcphdr) - optlen - hlen, oi) < 0) 4008 return (0); 4009 } else 4010 tb.t_flags = 0; 4011 4012 /* 4013 * See if we already have an entry for this connection. 4014 * If we do, resend the SYN,ACK. We do not count this 4015 * as a retransmission (XXX though maybe we should). 4016 */ 4017 if ((sc = syn_cache_lookup(src, dst, &scp)) != NULL) { 4018 tcpstat.tcps_sc_dupesyn++; 4019 if (ipopts) { 4020 /* 4021 * If we were remembering a previous source route, 4022 * forget it and use the new one we've been given. 4023 */ 4024 if (sc->sc_ipopts) 4025 (void) m_free(sc->sc_ipopts); 4026 sc->sc_ipopts = ipopts; 4027 } 4028 sc->sc_timestamp = tb.ts_recent; 4029 if (syn_cache_respond(sc, m) == 0) { 4030 tcpstat.tcps_sndacks++; 4031 tcpstat.tcps_sndtotal++; 4032 } 4033 return (1); 4034 } 4035 4036 sc = pool_get(&syn_cache_pool, PR_NOWAIT); 4037 if (sc == NULL) { 4038 if (ipopts) 4039 (void) m_free(ipopts); 4040 return (0); 4041 } 4042 4043 /* 4044 * Fill in the cache, and put the necessary IP and TCP 4045 * options into the reply. 4046 */ 4047 bzero(sc, sizeof(struct syn_cache)); 4048 callout_init(&sc->sc_timer); 4049 bcopy(src, &sc->sc_src, src->sa_len); 4050 bcopy(dst, &sc->sc_dst, dst->sa_len); 4051 sc->sc_flags = 0; 4052 sc->sc_ipopts = ipopts; 4053 sc->sc_irs = th->th_seq; 4054 switch (src->sa_family) { 4055 #ifdef INET 4056 case AF_INET: 4057 { 4058 struct sockaddr_in *srcin = (void *) src; 4059 struct sockaddr_in *dstin = (void *) dst; 4060 4061 sc->sc_iss = tcp_new_iss1(&dstin->sin_addr, 4062 &srcin->sin_addr, dstin->sin_port, 4063 srcin->sin_port, sizeof(dstin->sin_addr), 0); 4064 break; 4065 } 4066 #endif /* INET */ 4067 #ifdef INET6 4068 case AF_INET6: 4069 { 4070 struct sockaddr_in6 *srcin6 = (void *) src; 4071 struct sockaddr_in6 *dstin6 = (void *) dst; 4072 4073 sc->sc_iss = tcp_new_iss1(&dstin6->sin6_addr, 4074 &srcin6->sin6_addr, dstin6->sin6_port, 4075 srcin6->sin6_port, sizeof(dstin6->sin6_addr), 0); 4076 break; 4077 } 4078 #endif /* INET6 */ 4079 } 4080 sc->sc_peermaxseg = oi->maxseg; 4081 sc->sc_ourmaxseg = tcp_mss_to_advertise(m->m_flags & M_PKTHDR ? 4082 m->m_pkthdr.rcvif : NULL, 4083 sc->sc_src.sa.sa_family); 4084 sc->sc_win = win; 4085 sc->sc_timebase = tcp_now; /* see tcp_newtcpcb() */ 4086 sc->sc_timestamp = tb.ts_recent; 4087 if ((tb.t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP)) == 4088 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) 4089 sc->sc_flags |= SCF_TIMESTAMP; 4090 if ((tb.t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 4091 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 4092 sc->sc_requested_s_scale = tb.requested_s_scale; 4093 sc->sc_request_r_scale = 0; 4094 while (sc->sc_request_r_scale < TCP_MAX_WINSHIFT && 4095 TCP_MAXWIN << sc->sc_request_r_scale < 4096 so->so_rcv.sb_hiwat) 4097 sc->sc_request_r_scale++; 4098 } else { 4099 sc->sc_requested_s_scale = 15; 4100 sc->sc_request_r_scale = 15; 4101 } 4102 if ((tb.t_flags & TF_SACK_PERMIT) && tcp_do_sack) 4103 sc->sc_flags |= SCF_SACK_PERMIT; 4104 #ifdef TCP_SIGNATURE 4105 if (tb.t_flags & TF_SIGNATURE) 4106 sc->sc_flags |= SCF_SIGNATURE; 4107 #endif 4108 sc->sc_tp = tp; 4109 if (syn_cache_respond(sc, m) == 0) { 4110 syn_cache_insert(sc, tp); 4111 tcpstat.tcps_sndacks++; 4112 tcpstat.tcps_sndtotal++; 4113 } else { 4114 SYN_CACHE_PUT(sc); 4115 tcpstat.tcps_sc_dropped++; 4116 } 4117 return (1); 4118 } 4119 4120 int 4121 syn_cache_respond(struct syn_cache *sc, struct mbuf *m) 4122 { 4123 struct route *ro; 4124 u_int8_t *optp; 4125 int optlen, error; 4126 u_int16_t tlen; 4127 struct ip *ip = NULL; 4128 #ifdef INET6 4129 struct ip6_hdr *ip6 = NULL; 4130 #endif 4131 struct tcpcb *tp; 4132 struct tcphdr *th; 4133 u_int hlen; 4134 struct socket *so; 4135 4136 switch (sc->sc_src.sa.sa_family) { 4137 case AF_INET: 4138 hlen = sizeof(struct ip); 4139 ro = &sc->sc_route4; 4140 break; 4141 #ifdef INET6 4142 case AF_INET6: 4143 hlen = sizeof(struct ip6_hdr); 4144 ro = (struct route *)&sc->sc_route6; 4145 break; 4146 #endif 4147 default: 4148 if (m) 4149 m_freem(m); 4150 return (EAFNOSUPPORT); 4151 } 4152 4153 /* Compute the size of the TCP options. */ 4154 optlen = 4 + (sc->sc_request_r_scale != 15 ? 4 : 0) + 4155 ((sc->sc_flags & SCF_SACK_PERMIT) ? (TCPOLEN_SACK_PERMITTED + 2) : 0) + 4156 #ifdef TCP_SIGNATURE 4157 ((sc->sc_flags & SCF_SIGNATURE) ? (TCPOLEN_SIGNATURE + 2) : 0) + 4158 #endif 4159 ((sc->sc_flags & SCF_TIMESTAMP) ? TCPOLEN_TSTAMP_APPA : 0); 4160 4161 tlen = hlen + sizeof(struct tcphdr) + optlen; 4162 4163 /* 4164 * Create the IP+TCP header from scratch. 4165 */ 4166 if (m) 4167 m_freem(m); 4168 #ifdef DIAGNOSTIC 4169 if (max_linkhdr + tlen > MCLBYTES) 4170 return (ENOBUFS); 4171 #endif 4172 MGETHDR(m, M_DONTWAIT, MT_DATA); 4173 if (m && tlen > MHLEN) { 4174 MCLGET(m, M_DONTWAIT); 4175 if ((m->m_flags & M_EXT) == 0) { 4176 m_freem(m); 4177 m = NULL; 4178 } 4179 } 4180 if (m == NULL) 4181 return (ENOBUFS); 4182 MCLAIM(m, &tcp_tx_mowner); 4183 4184 /* Fixup the mbuf. */ 4185 m->m_data += max_linkhdr; 4186 m->m_len = m->m_pkthdr.len = tlen; 4187 if (sc->sc_tp) { 4188 tp = sc->sc_tp; 4189 if (tp->t_inpcb) 4190 so = tp->t_inpcb->inp_socket; 4191 #ifdef INET6 4192 else if (tp->t_in6pcb) 4193 so = tp->t_in6pcb->in6p_socket; 4194 #endif 4195 else 4196 so = NULL; 4197 } else 4198 so = NULL; 4199 m->m_pkthdr.rcvif = NULL; 4200 memset(mtod(m, u_char *), 0, tlen); 4201 4202 switch (sc->sc_src.sa.sa_family) { 4203 case AF_INET: 4204 ip = mtod(m, struct ip *); 4205 ip->ip_v = 4; 4206 ip->ip_dst = sc->sc_src.sin.sin_addr; 4207 ip->ip_src = sc->sc_dst.sin.sin_addr; 4208 ip->ip_p = IPPROTO_TCP; 4209 th = (struct tcphdr *)(ip + 1); 4210 th->th_dport = sc->sc_src.sin.sin_port; 4211 th->th_sport = sc->sc_dst.sin.sin_port; 4212 break; 4213 #ifdef INET6 4214 case AF_INET6: 4215 ip6 = mtod(m, struct ip6_hdr *); 4216 ip6->ip6_vfc = IPV6_VERSION; 4217 ip6->ip6_dst = sc->sc_src.sin6.sin6_addr; 4218 ip6->ip6_src = sc->sc_dst.sin6.sin6_addr; 4219 ip6->ip6_nxt = IPPROTO_TCP; 4220 /* ip6_plen will be updated in ip6_output() */ 4221 th = (struct tcphdr *)(ip6 + 1); 4222 th->th_dport = sc->sc_src.sin6.sin6_port; 4223 th->th_sport = sc->sc_dst.sin6.sin6_port; 4224 break; 4225 #endif 4226 default: 4227 th = NULL; 4228 } 4229 4230 th->th_seq = htonl(sc->sc_iss); 4231 th->th_ack = htonl(sc->sc_irs + 1); 4232 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 4233 th->th_flags = TH_SYN|TH_ACK; 4234 th->th_win = htons(sc->sc_win); 4235 /* th_sum already 0 */ 4236 /* th_urp already 0 */ 4237 4238 /* Tack on the TCP options. */ 4239 optp = (u_int8_t *)(th + 1); 4240 *optp++ = TCPOPT_MAXSEG; 4241 *optp++ = 4; 4242 *optp++ = (sc->sc_ourmaxseg >> 8) & 0xff; 4243 *optp++ = sc->sc_ourmaxseg & 0xff; 4244 4245 if (sc->sc_request_r_scale != 15) { 4246 *((u_int32_t *)optp) = htonl(TCPOPT_NOP << 24 | 4247 TCPOPT_WINDOW << 16 | TCPOLEN_WINDOW << 8 | 4248 sc->sc_request_r_scale); 4249 optp += 4; 4250 } 4251 4252 if (sc->sc_flags & SCF_TIMESTAMP) { 4253 u_int32_t *lp = (u_int32_t *)(optp); 4254 /* Form timestamp option as shown in appendix A of RFC 1323. */ 4255 *lp++ = htonl(TCPOPT_TSTAMP_HDR); 4256 *lp++ = htonl(SYN_CACHE_TIMESTAMP(sc)); 4257 *lp = htonl(sc->sc_timestamp); 4258 optp += TCPOLEN_TSTAMP_APPA; 4259 } 4260 4261 if (sc->sc_flags & SCF_SACK_PERMIT) { 4262 u_int8_t *p = optp; 4263 4264 /* Let the peer know that we will SACK. */ 4265 p[0] = TCPOPT_SACK_PERMITTED; 4266 p[1] = 2; 4267 p[2] = TCPOPT_NOP; 4268 p[3] = TCPOPT_NOP; 4269 optp += 4; 4270 } 4271 4272 #ifdef TCP_SIGNATURE 4273 if (sc->sc_flags & SCF_SIGNATURE) { 4274 struct secasvar *sav; 4275 u_int8_t *sigp; 4276 4277 sav = tcp_signature_getsav(m, th); 4278 4279 if (sav == NULL) { 4280 if (m) 4281 m_freem(m); 4282 return (EPERM); 4283 } 4284 4285 *optp++ = TCPOPT_SIGNATURE; 4286 *optp++ = TCPOLEN_SIGNATURE; 4287 sigp = optp; 4288 bzero(optp, TCP_SIGLEN); 4289 optp += TCP_SIGLEN; 4290 *optp++ = TCPOPT_NOP; 4291 *optp++ = TCPOPT_EOL; 4292 4293 (void)tcp_signature(m, th, hlen, sav, sigp); 4294 4295 key_sa_recordxfer(sav, m); 4296 #ifdef FAST_IPSEC 4297 KEY_FREESAV(&sav); 4298 #else 4299 key_freesav(sav); 4300 #endif 4301 } 4302 #endif 4303 4304 /* Compute the packet's checksum. */ 4305 switch (sc->sc_src.sa.sa_family) { 4306 case AF_INET: 4307 ip->ip_len = htons(tlen - hlen); 4308 th->th_sum = 0; 4309 th->th_sum = in4_cksum(m, IPPROTO_TCP, hlen, tlen - hlen); 4310 break; 4311 #ifdef INET6 4312 case AF_INET6: 4313 ip6->ip6_plen = htons(tlen - hlen); 4314 th->th_sum = 0; 4315 th->th_sum = in6_cksum(m, IPPROTO_TCP, hlen, tlen - hlen); 4316 break; 4317 #endif 4318 } 4319 4320 /* 4321 * Fill in some straggling IP bits. Note the stack expects 4322 * ip_len to be in host order, for convenience. 4323 */ 4324 switch (sc->sc_src.sa.sa_family) { 4325 #ifdef INET 4326 case AF_INET: 4327 ip->ip_len = htons(tlen); 4328 ip->ip_ttl = ip_defttl; 4329 /* XXX tos? */ 4330 break; 4331 #endif 4332 #ifdef INET6 4333 case AF_INET6: 4334 ip6->ip6_vfc &= ~IPV6_VERSION_MASK; 4335 ip6->ip6_vfc |= IPV6_VERSION; 4336 ip6->ip6_plen = htons(tlen - hlen); 4337 /* ip6_hlim will be initialized afterwards */ 4338 /* XXX flowlabel? */ 4339 break; 4340 #endif 4341 } 4342 4343 /* XXX use IPsec policy on listening socket, on SYN ACK */ 4344 tp = sc->sc_tp; 4345 4346 switch (sc->sc_src.sa.sa_family) { 4347 #ifdef INET 4348 case AF_INET: 4349 error = ip_output(m, sc->sc_ipopts, ro, 4350 (ip_mtudisc ? IP_MTUDISC : 0), 4351 (struct ip_moptions *)NULL, so); 4352 break; 4353 #endif 4354 #ifdef INET6 4355 case AF_INET6: 4356 ip6->ip6_hlim = in6_selecthlim(NULL, 4357 ro->ro_rt ? ro->ro_rt->rt_ifp : NULL); 4358 4359 error = ip6_output(m, NULL /*XXX*/, (struct route_in6 *)ro, 0, 4360 (struct ip6_moptions *)0, so, NULL); 4361 break; 4362 #endif 4363 default: 4364 error = EAFNOSUPPORT; 4365 break; 4366 } 4367 return (error); 4368 } 4369