1 /* $NetBSD: tcp_input.c,v 1.407 2018/05/03 07:13:48 maxv 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, 2006, 74 * 2011 The NetBSD Foundation, Inc. 75 * All rights reserved. 76 * 77 * This code is derived from software contributed to The NetBSD Foundation 78 * by Coyote Point Systems, Inc. 79 * This code is derived from software contributed to The NetBSD Foundation 80 * by Jason R. Thorpe and Kevin M. Lahey of the Numerical Aerospace Simulation 81 * Facility, NASA Ames Research Center. 82 * This code is derived from software contributed to The NetBSD Foundation 83 * by Charles M. Hannum. 84 * This code is derived from software contributed to The NetBSD Foundation 85 * by Rui Paulo. 86 * 87 * Redistribution and use in source and binary forms, with or without 88 * modification, are permitted provided that the following conditions 89 * are met: 90 * 1. Redistributions of source code must retain the above copyright 91 * notice, this list of conditions and the following disclaimer. 92 * 2. Redistributions in binary form must reproduce the above copyright 93 * notice, this list of conditions and the following disclaimer in the 94 * documentation and/or other materials provided with the distribution. 95 * 96 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 97 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 98 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 99 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 100 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 101 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 102 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 103 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 104 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 105 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 106 * POSSIBILITY OF SUCH DAMAGE. 107 */ 108 109 /* 110 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995 111 * The Regents of the University of California. All rights reserved. 112 * 113 * Redistribution and use in source and binary forms, with or without 114 * modification, are permitted provided that the following conditions 115 * are met: 116 * 1. Redistributions of source code must retain the above copyright 117 * notice, this list of conditions and the following disclaimer. 118 * 2. Redistributions in binary form must reproduce the above copyright 119 * notice, this list of conditions and the following disclaimer in the 120 * documentation and/or other materials provided with the distribution. 121 * 3. Neither the name of the University nor the names of its contributors 122 * may be used to endorse or promote products derived from this software 123 * without specific prior written permission. 124 * 125 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 126 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 127 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 128 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 129 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 130 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 131 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 132 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 133 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 134 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 135 * SUCH DAMAGE. 136 * 137 * @(#)tcp_input.c 8.12 (Berkeley) 5/24/95 138 */ 139 140 /* 141 * TODO list for SYN cache stuff: 142 * 143 * Find room for a "state" field, which is needed to keep a 144 * compressed state for TIME_WAIT TCBs. It's been noted already 145 * that this is fairly important for very high-volume web and 146 * mail servers, which use a large number of short-lived 147 * connections. 148 */ 149 150 #include <sys/cdefs.h> 151 __KERNEL_RCSID(0, "$NetBSD: tcp_input.c,v 1.407 2018/05/03 07:13:48 maxv Exp $"); 152 153 #ifdef _KERNEL_OPT 154 #include "opt_inet.h" 155 #include "opt_ipsec.h" 156 #include "opt_inet_csum.h" 157 #include "opt_tcp_debug.h" 158 #endif 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 #include <sys/lwp.h> /* for lwp0 */ 176 #include <sys/cprng.h> 177 178 #include <net/if.h> 179 #include <net/if_types.h> 180 181 #include <netinet/in.h> 182 #include <netinet/in_systm.h> 183 #include <netinet/ip.h> 184 #include <netinet/in_pcb.h> 185 #include <netinet/in_var.h> 186 #include <netinet/ip_var.h> 187 #include <netinet/in_offload.h> 188 189 #ifdef INET6 190 #include <netinet/ip6.h> 191 #include <netinet6/ip6_var.h> 192 #include <netinet6/in6_pcb.h> 193 #include <netinet6/ip6_var.h> 194 #include <netinet6/in6_var.h> 195 #include <netinet/icmp6.h> 196 #include <netinet6/nd6.h> 197 #ifdef TCP_SIGNATURE 198 #include <netinet6/scope6_var.h> 199 #endif 200 #endif 201 202 #ifndef INET6 203 /* always need ip6.h for IP6_EXTHDR_GET */ 204 #include <netinet/ip6.h> 205 #endif 206 207 #include <netinet/tcp.h> 208 #include <netinet/tcp_fsm.h> 209 #include <netinet/tcp_seq.h> 210 #include <netinet/tcp_timer.h> 211 #include <netinet/tcp_var.h> 212 #include <netinet/tcp_private.h> 213 #include <netinet/tcp_congctl.h> 214 #include <netinet/tcp_debug.h> 215 216 #ifdef INET6 217 #include "faith.h" 218 #if defined(NFAITH) && NFAITH > 0 219 #include <net/if_faith.h> 220 #endif 221 #endif 222 223 #ifdef IPSEC 224 #include <netipsec/ipsec.h> 225 #include <netipsec/key.h> 226 #ifdef INET6 227 #include <netipsec/ipsec6.h> 228 #endif 229 #endif /* IPSEC*/ 230 231 #include <netinet/tcp_vtw.h> 232 233 int tcprexmtthresh = 3; 234 int tcp_log_refused; 235 236 int tcp_do_autorcvbuf = 1; 237 int tcp_autorcvbuf_inc = 16 * 1024; 238 int tcp_autorcvbuf_max = 256 * 1024; 239 int tcp_msl = (TCPTV_MSL / PR_SLOWHZ); 240 241 static int tcp_rst_ppslim_count = 0; 242 static struct timeval tcp_rst_ppslim_last; 243 static int tcp_ackdrop_ppslim_count = 0; 244 static struct timeval tcp_ackdrop_ppslim_last; 245 246 static void syn_cache_timer(void *); 247 248 #define TCP_PAWS_IDLE (24U * 24 * 60 * 60 * PR_SLOWHZ) 249 250 /* for modulo comparisons of timestamps */ 251 #define TSTMP_LT(a,b) ((int)((a)-(b)) < 0) 252 #define TSTMP_GEQ(a,b) ((int)((a)-(b)) >= 0) 253 254 /* 255 * Neighbor Discovery, Neighbor Unreachability Detection Upper layer hint. 256 */ 257 #ifdef INET6 258 static inline void 259 nd6_hint(struct tcpcb *tp) 260 { 261 struct rtentry *rt = NULL; 262 263 if (tp != NULL && tp->t_in6pcb != NULL && tp->t_family == AF_INET6 && 264 (rt = rtcache_validate(&tp->t_in6pcb->in6p_route)) != NULL) 265 nd6_nud_hint(rt); 266 rtcache_unref(rt, &tp->t_in6pcb->in6p_route); 267 } 268 #else 269 static inline void 270 nd6_hint(struct tcpcb *tp) 271 { 272 } 273 #endif 274 275 /* 276 * Compute ACK transmission behavior. Delay the ACK unless 277 * we have already delayed an ACK (must send an ACK every two segments). 278 * We also ACK immediately if we received a PUSH and the ACK-on-PUSH 279 * option is enabled. 280 */ 281 static void 282 tcp_setup_ack(struct tcpcb *tp, const struct tcphdr *th) 283 { 284 285 if (tp->t_flags & TF_DELACK || 286 (tcp_ack_on_push && th->th_flags & TH_PUSH)) 287 tp->t_flags |= TF_ACKNOW; 288 else 289 TCP_SET_DELACK(tp); 290 } 291 292 static void 293 icmp_check(struct tcpcb *tp, const struct tcphdr *th, int acked) 294 { 295 296 /* 297 * If we had a pending ICMP message that refers to data that have 298 * just been acknowledged, disregard the recorded ICMP message. 299 */ 300 if ((tp->t_flags & TF_PMTUD_PEND) && 301 SEQ_GT(th->th_ack, tp->t_pmtud_th_seq)) 302 tp->t_flags &= ~TF_PMTUD_PEND; 303 304 /* 305 * Keep track of the largest chunk of data 306 * acknowledged since last PMTU update 307 */ 308 if (tp->t_pmtud_mss_acked < acked) 309 tp->t_pmtud_mss_acked = acked; 310 } 311 312 /* 313 * Convert TCP protocol fields to host order for easier processing. 314 */ 315 static void 316 tcp_fields_to_host(struct tcphdr *th) 317 { 318 319 NTOHL(th->th_seq); 320 NTOHL(th->th_ack); 321 NTOHS(th->th_win); 322 NTOHS(th->th_urp); 323 } 324 325 /* 326 * ... and reverse the above. 327 */ 328 static void 329 tcp_fields_to_net(struct tcphdr *th) 330 { 331 332 HTONL(th->th_seq); 333 HTONL(th->th_ack); 334 HTONS(th->th_win); 335 HTONS(th->th_urp); 336 } 337 338 static void 339 tcp_urp_drop(struct tcphdr *th, int todrop, int *tiflags) 340 { 341 if (th->th_urp > todrop) { 342 th->th_urp -= todrop; 343 } else { 344 *tiflags &= ~TH_URG; 345 th->th_urp = 0; 346 } 347 } 348 349 #ifdef TCP_CSUM_COUNTERS 350 #include <sys/device.h> 351 352 extern struct evcnt tcp_hwcsum_ok; 353 extern struct evcnt tcp_hwcsum_bad; 354 extern struct evcnt tcp_hwcsum_data; 355 extern struct evcnt tcp_swcsum; 356 #if defined(INET6) 357 extern struct evcnt tcp6_hwcsum_ok; 358 extern struct evcnt tcp6_hwcsum_bad; 359 extern struct evcnt tcp6_hwcsum_data; 360 extern struct evcnt tcp6_swcsum; 361 #endif /* defined(INET6) */ 362 363 #define TCP_CSUM_COUNTER_INCR(ev) (ev)->ev_count++ 364 365 #else 366 367 #define TCP_CSUM_COUNTER_INCR(ev) /* nothing */ 368 369 #endif /* TCP_CSUM_COUNTERS */ 370 371 #ifdef TCP_REASS_COUNTERS 372 #include <sys/device.h> 373 374 extern struct evcnt tcp_reass_; 375 extern struct evcnt tcp_reass_empty; 376 extern struct evcnt tcp_reass_iteration[8]; 377 extern struct evcnt tcp_reass_prependfirst; 378 extern struct evcnt tcp_reass_prepend; 379 extern struct evcnt tcp_reass_insert; 380 extern struct evcnt tcp_reass_inserttail; 381 extern struct evcnt tcp_reass_append; 382 extern struct evcnt tcp_reass_appendtail; 383 extern struct evcnt tcp_reass_overlaptail; 384 extern struct evcnt tcp_reass_overlapfront; 385 extern struct evcnt tcp_reass_segdup; 386 extern struct evcnt tcp_reass_fragdup; 387 388 #define TCP_REASS_COUNTER_INCR(ev) (ev)->ev_count++ 389 390 #else 391 392 #define TCP_REASS_COUNTER_INCR(ev) /* nothing */ 393 394 #endif /* TCP_REASS_COUNTERS */ 395 396 static int tcp_reass(struct tcpcb *, const struct tcphdr *, struct mbuf *, 397 int); 398 static int tcp_dooptions(struct tcpcb *, const u_char *, int, 399 struct tcphdr *, struct mbuf *, int, struct tcp_opt_info *); 400 401 static void tcp4_log_refused(const struct ip *, const struct tcphdr *); 402 #ifdef INET6 403 static void tcp6_log_refused(const struct ip6_hdr *, const struct tcphdr *); 404 #endif 405 406 #if defined(MBUFTRACE) 407 struct mowner tcp_reass_mowner = MOWNER_INIT("tcp", "reass"); 408 #endif /* defined(MBUFTRACE) */ 409 410 static struct pool tcpipqent_pool; 411 412 void 413 tcpipqent_init(void) 414 { 415 416 pool_init(&tcpipqent_pool, sizeof(struct ipqent), 0, 0, 0, "tcpipqepl", 417 NULL, IPL_VM); 418 } 419 420 struct ipqent * 421 tcpipqent_alloc(void) 422 { 423 struct ipqent *ipqe; 424 int s; 425 426 s = splvm(); 427 ipqe = pool_get(&tcpipqent_pool, PR_NOWAIT); 428 splx(s); 429 430 return ipqe; 431 } 432 433 void 434 tcpipqent_free(struct ipqent *ipqe) 435 { 436 int s; 437 438 s = splvm(); 439 pool_put(&tcpipqent_pool, ipqe); 440 splx(s); 441 } 442 443 /* 444 * Insert segment ti into reassembly queue of tcp with 445 * control block tp. Return TH_FIN if reassembly now includes 446 * a segment with FIN. 447 */ 448 static int 449 tcp_reass(struct tcpcb *tp, const struct tcphdr *th, struct mbuf *m, int tlen) 450 { 451 struct ipqent *p, *q, *nq, *tiqe = NULL; 452 struct socket *so = NULL; 453 int pkt_flags; 454 tcp_seq pkt_seq; 455 unsigned pkt_len; 456 u_long rcvpartdupbyte = 0; 457 u_long rcvoobyte; 458 #ifdef TCP_REASS_COUNTERS 459 u_int count = 0; 460 #endif 461 uint64_t *tcps; 462 463 if (tp->t_inpcb) 464 so = tp->t_inpcb->inp_socket; 465 #ifdef INET6 466 else if (tp->t_in6pcb) 467 so = tp->t_in6pcb->in6p_socket; 468 #endif 469 470 TCP_REASS_LOCK_CHECK(tp); 471 472 /* 473 * Call with th==NULL after become established to 474 * force pre-ESTABLISHED data up to user socket. 475 */ 476 if (th == NULL) 477 goto present; 478 479 m_claimm(m, &tcp_reass_mowner); 480 481 rcvoobyte = tlen; 482 /* 483 * Copy these to local variables because the TCP header gets munged 484 * while we are collapsing mbufs. 485 */ 486 pkt_seq = th->th_seq; 487 pkt_len = tlen; 488 pkt_flags = th->th_flags; 489 490 TCP_REASS_COUNTER_INCR(&tcp_reass_); 491 492 if ((p = TAILQ_LAST(&tp->segq, ipqehead)) != NULL) { 493 /* 494 * When we miss a packet, the vast majority of time we get 495 * packets that follow it in order. So optimize for that. 496 */ 497 if (pkt_seq == p->ipqe_seq + p->ipqe_len) { 498 p->ipqe_len += pkt_len; 499 p->ipqe_flags |= pkt_flags; 500 m_cat(p->ipqe_m, m); 501 m = NULL; 502 tiqe = p; 503 TAILQ_REMOVE(&tp->timeq, p, ipqe_timeq); 504 TCP_REASS_COUNTER_INCR(&tcp_reass_appendtail); 505 goto skip_replacement; 506 } 507 /* 508 * While we're here, if the pkt is completely beyond 509 * anything we have, just insert it at the tail. 510 */ 511 if (SEQ_GT(pkt_seq, p->ipqe_seq + p->ipqe_len)) { 512 TCP_REASS_COUNTER_INCR(&tcp_reass_inserttail); 513 goto insert_it; 514 } 515 } 516 517 q = TAILQ_FIRST(&tp->segq); 518 519 if (q != NULL) { 520 /* 521 * If this segment immediately precedes the first out-of-order 522 * block, simply slap the segment in front of it and (mostly) 523 * skip the complicated logic. 524 */ 525 if (pkt_seq + pkt_len == q->ipqe_seq) { 526 q->ipqe_seq = pkt_seq; 527 q->ipqe_len += pkt_len; 528 q->ipqe_flags |= pkt_flags; 529 m_cat(m, q->ipqe_m); 530 q->ipqe_m = m; 531 tiqe = q; 532 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 533 TCP_REASS_COUNTER_INCR(&tcp_reass_prependfirst); 534 goto skip_replacement; 535 } 536 } else { 537 TCP_REASS_COUNTER_INCR(&tcp_reass_empty); 538 } 539 540 /* 541 * Find a segment which begins after this one does. 542 */ 543 for (p = NULL; q != NULL; q = nq) { 544 nq = TAILQ_NEXT(q, ipqe_q); 545 #ifdef TCP_REASS_COUNTERS 546 count++; 547 #endif 548 549 /* 550 * If the received segment is just right after this 551 * fragment, merge the two together and then check 552 * for further overlaps. 553 */ 554 if (q->ipqe_seq + q->ipqe_len == pkt_seq) { 555 pkt_len += q->ipqe_len; 556 pkt_flags |= q->ipqe_flags; 557 pkt_seq = q->ipqe_seq; 558 m_cat(q->ipqe_m, m); 559 m = q->ipqe_m; 560 TCP_REASS_COUNTER_INCR(&tcp_reass_append); 561 goto free_ipqe; 562 } 563 564 /* 565 * If the received segment is completely past this 566 * fragment, we need to go to the next fragment. 567 */ 568 if (SEQ_LT(q->ipqe_seq + q->ipqe_len, pkt_seq)) { 569 p = q; 570 continue; 571 } 572 573 /* 574 * If the fragment is past the received segment, 575 * it (or any following) can't be concatenated. 576 */ 577 if (SEQ_GT(q->ipqe_seq, pkt_seq + pkt_len)) { 578 TCP_REASS_COUNTER_INCR(&tcp_reass_insert); 579 break; 580 } 581 582 /* 583 * We've received all the data in this segment before. 584 * Mark it as a duplicate and return. 585 */ 586 if (SEQ_LEQ(q->ipqe_seq, pkt_seq) && 587 SEQ_GEQ(q->ipqe_seq + q->ipqe_len, pkt_seq + pkt_len)) { 588 tcps = TCP_STAT_GETREF(); 589 tcps[TCP_STAT_RCVDUPPACK]++; 590 tcps[TCP_STAT_RCVDUPBYTE] += pkt_len; 591 TCP_STAT_PUTREF(); 592 tcp_new_dsack(tp, pkt_seq, pkt_len); 593 m_freem(m); 594 if (tiqe != NULL) { 595 tcpipqent_free(tiqe); 596 } 597 TCP_REASS_COUNTER_INCR(&tcp_reass_segdup); 598 goto out; 599 } 600 601 /* 602 * Received segment completely overlaps this fragment 603 * so we drop the fragment (this keeps the temporal 604 * ordering of segments correct). 605 */ 606 if (SEQ_GEQ(q->ipqe_seq, pkt_seq) && 607 SEQ_LEQ(q->ipqe_seq + q->ipqe_len, pkt_seq + pkt_len)) { 608 rcvpartdupbyte += q->ipqe_len; 609 m_freem(q->ipqe_m); 610 TCP_REASS_COUNTER_INCR(&tcp_reass_fragdup); 611 goto free_ipqe; 612 } 613 614 /* 615 * Received segment extends past the end of the fragment. 616 * Drop the overlapping bytes, merge the fragment and 617 * segment, and treat as a longer received packet. 618 */ 619 if (SEQ_LT(q->ipqe_seq, pkt_seq) && 620 SEQ_GT(q->ipqe_seq + q->ipqe_len, pkt_seq)) { 621 int overlap = q->ipqe_seq + q->ipqe_len - pkt_seq; 622 m_adj(m, overlap); 623 rcvpartdupbyte += overlap; 624 m_cat(q->ipqe_m, m); 625 m = q->ipqe_m; 626 pkt_seq = q->ipqe_seq; 627 pkt_len += q->ipqe_len - overlap; 628 rcvoobyte -= overlap; 629 TCP_REASS_COUNTER_INCR(&tcp_reass_overlaptail); 630 goto free_ipqe; 631 } 632 633 /* 634 * Received segment extends past the front of the fragment. 635 * Drop the overlapping bytes on the received packet. The 636 * packet will then be concatenated with this fragment a 637 * bit later. 638 */ 639 if (SEQ_GT(q->ipqe_seq, pkt_seq) && 640 SEQ_LT(q->ipqe_seq, pkt_seq + pkt_len)) { 641 int overlap = pkt_seq + pkt_len - q->ipqe_seq; 642 m_adj(m, -overlap); 643 pkt_len -= overlap; 644 rcvpartdupbyte += overlap; 645 TCP_REASS_COUNTER_INCR(&tcp_reass_overlapfront); 646 rcvoobyte -= overlap; 647 } 648 649 /* 650 * If the received segment immediately precedes this 651 * fragment then tack the fragment onto this segment 652 * and reinsert the data. 653 */ 654 if (q->ipqe_seq == pkt_seq + pkt_len) { 655 pkt_len += q->ipqe_len; 656 pkt_flags |= q->ipqe_flags; 657 m_cat(m, q->ipqe_m); 658 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 659 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 660 tp->t_segqlen--; 661 KASSERT(tp->t_segqlen >= 0); 662 KASSERT(tp->t_segqlen != 0 || 663 (TAILQ_EMPTY(&tp->segq) && 664 TAILQ_EMPTY(&tp->timeq))); 665 if (tiqe == NULL) { 666 tiqe = q; 667 } else { 668 tcpipqent_free(q); 669 } 670 TCP_REASS_COUNTER_INCR(&tcp_reass_prepend); 671 break; 672 } 673 674 /* 675 * If the fragment is before the segment, remember it. 676 * When this loop is terminated, p will contain the 677 * pointer to the fragment that is right before the 678 * received segment. 679 */ 680 if (SEQ_LEQ(q->ipqe_seq, pkt_seq)) 681 p = q; 682 683 continue; 684 685 /* 686 * This is a common operation. It also will allow 687 * to save doing a malloc/free in most instances. 688 */ 689 free_ipqe: 690 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 691 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 692 tp->t_segqlen--; 693 KASSERT(tp->t_segqlen >= 0); 694 KASSERT(tp->t_segqlen != 0 || 695 (TAILQ_EMPTY(&tp->segq) && TAILQ_EMPTY(&tp->timeq))); 696 if (tiqe == NULL) { 697 tiqe = q; 698 } else { 699 tcpipqent_free(q); 700 } 701 } 702 703 #ifdef TCP_REASS_COUNTERS 704 if (count > 7) 705 TCP_REASS_COUNTER_INCR(&tcp_reass_iteration[0]); 706 else if (count > 0) 707 TCP_REASS_COUNTER_INCR(&tcp_reass_iteration[count]); 708 #endif 709 710 insert_it: 711 /* 712 * Allocate a new queue entry (block) since the received segment 713 * did not collapse onto any other out-of-order block. If it had 714 * collapsed, tiqe would not be NULL and we would be reusing it. 715 * 716 * If the allocation fails, drop the packet. 717 */ 718 if (tiqe == NULL) { 719 tiqe = tcpipqent_alloc(); 720 if (tiqe == NULL) { 721 TCP_STATINC(TCP_STAT_RCVMEMDROP); 722 m_freem(m); 723 goto out; 724 } 725 } 726 727 /* 728 * Update the counters. 729 */ 730 tp->t_rcvoopack++; 731 tcps = TCP_STAT_GETREF(); 732 tcps[TCP_STAT_RCVOOPACK]++; 733 tcps[TCP_STAT_RCVOOBYTE] += rcvoobyte; 734 if (rcvpartdupbyte) { 735 tcps[TCP_STAT_RCVPARTDUPPACK]++; 736 tcps[TCP_STAT_RCVPARTDUPBYTE] += rcvpartdupbyte; 737 } 738 TCP_STAT_PUTREF(); 739 740 /* 741 * Insert the new fragment queue entry into both queues. 742 */ 743 tiqe->ipqe_m = m; 744 tiqe->ipqe_seq = pkt_seq; 745 tiqe->ipqe_len = pkt_len; 746 tiqe->ipqe_flags = pkt_flags; 747 if (p == NULL) { 748 TAILQ_INSERT_HEAD(&tp->segq, tiqe, ipqe_q); 749 } else { 750 TAILQ_INSERT_AFTER(&tp->segq, p, tiqe, ipqe_q); 751 } 752 tp->t_segqlen++; 753 754 skip_replacement: 755 TAILQ_INSERT_HEAD(&tp->timeq, tiqe, ipqe_timeq); 756 757 present: 758 /* 759 * Present data to user, advancing rcv_nxt through 760 * completed sequence space. 761 */ 762 if (TCPS_HAVEESTABLISHED(tp->t_state) == 0) 763 goto out; 764 q = TAILQ_FIRST(&tp->segq); 765 if (q == NULL || q->ipqe_seq != tp->rcv_nxt) 766 goto out; 767 if (tp->t_state == TCPS_SYN_RECEIVED && q->ipqe_len) 768 goto out; 769 770 tp->rcv_nxt += q->ipqe_len; 771 pkt_flags = q->ipqe_flags & TH_FIN; 772 nd6_hint(tp); 773 774 TAILQ_REMOVE(&tp->segq, q, ipqe_q); 775 TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq); 776 tp->t_segqlen--; 777 KASSERT(tp->t_segqlen >= 0); 778 KASSERT(tp->t_segqlen != 0 || 779 (TAILQ_EMPTY(&tp->segq) && TAILQ_EMPTY(&tp->timeq))); 780 if (so->so_state & SS_CANTRCVMORE) 781 m_freem(q->ipqe_m); 782 else 783 sbappendstream(&so->so_rcv, q->ipqe_m); 784 tcpipqent_free(q); 785 TCP_REASS_UNLOCK(tp); 786 sorwakeup(so); 787 return pkt_flags; 788 789 out: 790 TCP_REASS_UNLOCK(tp); 791 return 0; 792 } 793 794 #ifdef INET6 795 int 796 tcp6_input(struct mbuf **mp, int *offp, int proto) 797 { 798 struct mbuf *m = *mp; 799 800 /* 801 * draft-itojun-ipv6-tcp-to-anycast 802 * better place to put this in? 803 */ 804 if (m->m_flags & M_ANYCAST6) { 805 struct ip6_hdr *ip6; 806 if (m->m_len < sizeof(struct ip6_hdr)) { 807 if ((m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) { 808 TCP_STATINC(TCP_STAT_RCVSHORT); 809 return IPPROTO_DONE; 810 } 811 } 812 ip6 = mtod(m, struct ip6_hdr *); 813 icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR, 814 (char *)&ip6->ip6_dst - (char *)ip6); 815 return IPPROTO_DONE; 816 } 817 818 tcp_input(m, *offp, proto); 819 return IPPROTO_DONE; 820 } 821 #endif 822 823 static void 824 tcp4_log_refused(const struct ip *ip, const struct tcphdr *th) 825 { 826 char src[INET_ADDRSTRLEN]; 827 char dst[INET_ADDRSTRLEN]; 828 829 if (ip) { 830 in_print(src, sizeof(src), &ip->ip_src); 831 in_print(dst, sizeof(dst), &ip->ip_dst); 832 } else { 833 strlcpy(src, "(unknown)", sizeof(src)); 834 strlcpy(dst, "(unknown)", sizeof(dst)); 835 } 836 log(LOG_INFO, 837 "Connection attempt to TCP %s:%d from %s:%d\n", 838 dst, ntohs(th->th_dport), 839 src, ntohs(th->th_sport)); 840 } 841 842 #ifdef INET6 843 static void 844 tcp6_log_refused(const struct ip6_hdr *ip6, const struct tcphdr *th) 845 { 846 char src[INET6_ADDRSTRLEN]; 847 char dst[INET6_ADDRSTRLEN]; 848 849 if (ip6) { 850 in6_print(src, sizeof(src), &ip6->ip6_src); 851 in6_print(dst, sizeof(dst), &ip6->ip6_dst); 852 } else { 853 strlcpy(src, "(unknown v6)", sizeof(src)); 854 strlcpy(dst, "(unknown v6)", sizeof(dst)); 855 } 856 log(LOG_INFO, 857 "Connection attempt to TCP [%s]:%d from [%s]:%d\n", 858 dst, ntohs(th->th_dport), 859 src, ntohs(th->th_sport)); 860 } 861 #endif 862 863 /* 864 * Checksum extended TCP header and data. 865 */ 866 int 867 tcp_input_checksum(int af, struct mbuf *m, const struct tcphdr *th, 868 int toff, int off, int tlen) 869 { 870 struct ifnet *rcvif; 871 int s; 872 873 /* 874 * XXX it's better to record and check if this mbuf is 875 * already checked. 876 */ 877 878 rcvif = m_get_rcvif(m, &s); 879 if (__predict_false(rcvif == NULL)) 880 goto badcsum; /* XXX */ 881 882 switch (af) { 883 case AF_INET: 884 switch (m->m_pkthdr.csum_flags & 885 ((rcvif->if_csum_flags_rx & M_CSUM_TCPv4) | 886 M_CSUM_TCP_UDP_BAD | M_CSUM_DATA)) { 887 case M_CSUM_TCPv4|M_CSUM_TCP_UDP_BAD: 888 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_bad); 889 goto badcsum; 890 891 case M_CSUM_TCPv4|M_CSUM_DATA: { 892 u_int32_t hw_csum = m->m_pkthdr.csum_data; 893 894 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_data); 895 if (m->m_pkthdr.csum_flags & M_CSUM_NO_PSEUDOHDR) { 896 const struct ip *ip = 897 mtod(m, const struct ip *); 898 899 hw_csum = in_cksum_phdr(ip->ip_src.s_addr, 900 ip->ip_dst.s_addr, 901 htons(hw_csum + tlen + off + IPPROTO_TCP)); 902 } 903 if ((hw_csum ^ 0xffff) != 0) 904 goto badcsum; 905 break; 906 } 907 908 case M_CSUM_TCPv4: 909 /* Checksum was okay. */ 910 TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_ok); 911 break; 912 913 default: 914 /* 915 * Must compute it ourselves. Maybe skip checksum 916 * on loopback interfaces. 917 */ 918 if (__predict_true(!(rcvif->if_flags & IFF_LOOPBACK) || 919 tcp_do_loopback_cksum)) { 920 TCP_CSUM_COUNTER_INCR(&tcp_swcsum); 921 if (in4_cksum(m, IPPROTO_TCP, toff, 922 tlen + off) != 0) 923 goto badcsum; 924 } 925 break; 926 } 927 break; 928 929 #ifdef INET6 930 case AF_INET6: 931 switch (m->m_pkthdr.csum_flags & 932 ((rcvif->if_csum_flags_rx & M_CSUM_TCPv6) | 933 M_CSUM_TCP_UDP_BAD | M_CSUM_DATA)) { 934 case M_CSUM_TCPv6|M_CSUM_TCP_UDP_BAD: 935 TCP_CSUM_COUNTER_INCR(&tcp6_hwcsum_bad); 936 goto badcsum; 937 938 #if 0 /* notyet */ 939 case M_CSUM_TCPv6|M_CSUM_DATA: 940 #endif 941 942 case M_CSUM_TCPv6: 943 /* Checksum was okay. */ 944 TCP_CSUM_COUNTER_INCR(&tcp6_hwcsum_ok); 945 break; 946 947 default: 948 /* 949 * Must compute it ourselves. Maybe skip checksum 950 * on loopback interfaces. 951 */ 952 if (__predict_true((m->m_flags & M_LOOP) == 0 || 953 tcp_do_loopback_cksum)) { 954 TCP_CSUM_COUNTER_INCR(&tcp6_swcsum); 955 if (in6_cksum(m, IPPROTO_TCP, toff, 956 tlen + off) != 0) 957 goto badcsum; 958 } 959 } 960 break; 961 #endif /* INET6 */ 962 } 963 m_put_rcvif(rcvif, &s); 964 965 return 0; 966 967 badcsum: 968 m_put_rcvif(rcvif, &s); 969 TCP_STATINC(TCP_STAT_RCVBADSUM); 970 return -1; 971 } 972 973 /* 974 * When a packet arrives addressed to a vestigial tcpbp, we 975 * nevertheless have to respond to it per the spec. 976 * 977 * This code is duplicated from the one in tcp_input(). 978 */ 979 static void tcp_vtw_input(struct tcphdr *th, vestigial_inpcb_t *vp, 980 struct mbuf *m, int tlen) 981 { 982 int tiflags; 983 int todrop; 984 uint32_t t_flags = 0; 985 uint64_t *tcps; 986 987 tiflags = th->th_flags; 988 todrop = vp->rcv_nxt - th->th_seq; 989 990 if (todrop > 0) { 991 if (tiflags & TH_SYN) { 992 tiflags &= ~TH_SYN; 993 th->th_seq++; 994 tcp_urp_drop(th, 1, &tiflags); 995 todrop--; 996 } 997 if (todrop > tlen || 998 (todrop == tlen && (tiflags & TH_FIN) == 0)) { 999 /* 1000 * Any valid FIN or RST must be to the left of the 1001 * window. At this point the FIN or RST must be a 1002 * duplicate or out of sequence; drop it. 1003 */ 1004 if (tiflags & TH_RST) 1005 goto drop; 1006 tiflags &= ~(TH_FIN|TH_RST); 1007 1008 /* 1009 * Send an ACK to resynchronize and drop any data. 1010 * But keep on processing for RST or ACK. 1011 */ 1012 t_flags |= TF_ACKNOW; 1013 todrop = tlen; 1014 tcps = TCP_STAT_GETREF(); 1015 tcps[TCP_STAT_RCVDUPPACK] += 1; 1016 tcps[TCP_STAT_RCVDUPBYTE] += todrop; 1017 TCP_STAT_PUTREF(); 1018 } else if ((tiflags & TH_RST) && 1019 th->th_seq != vp->rcv_nxt) { 1020 /* 1021 * Test for reset before adjusting the sequence 1022 * number for overlapping data. 1023 */ 1024 goto dropafterack_ratelim; 1025 } else { 1026 tcps = TCP_STAT_GETREF(); 1027 tcps[TCP_STAT_RCVPARTDUPPACK] += 1; 1028 tcps[TCP_STAT_RCVPARTDUPBYTE] += todrop; 1029 TCP_STAT_PUTREF(); 1030 } 1031 1032 // tcp_new_dsack(tp, th->th_seq, todrop); 1033 // hdroptlen += todrop; /*drop from head afterwards*/ 1034 1035 th->th_seq += todrop; 1036 tlen -= todrop; 1037 tcp_urp_drop(th, todrop, &tiflags); 1038 } 1039 1040 /* 1041 * If new data are received on a connection after the 1042 * user processes are gone, then RST the other end. 1043 */ 1044 if (tlen) { 1045 TCP_STATINC(TCP_STAT_RCVAFTERCLOSE); 1046 goto dropwithreset; 1047 } 1048 1049 /* 1050 * If segment ends after window, drop trailing data 1051 * (and PUSH and FIN); if nothing left, just ACK. 1052 */ 1053 todrop = (th->th_seq + tlen) - (vp->rcv_nxt + vp->rcv_wnd); 1054 1055 if (todrop > 0) { 1056 TCP_STATINC(TCP_STAT_RCVPACKAFTERWIN); 1057 if (todrop >= tlen) { 1058 /* 1059 * The segment actually starts after the window. 1060 * th->th_seq + tlen - vp->rcv_nxt - vp->rcv_wnd >= tlen 1061 * th->th_seq - vp->rcv_nxt - vp->rcv_wnd >= 0 1062 * th->th_seq >= vp->rcv_nxt + vp->rcv_wnd 1063 */ 1064 TCP_STATADD(TCP_STAT_RCVBYTEAFTERWIN, tlen); 1065 1066 /* 1067 * If a new connection request is received 1068 * while in TIME_WAIT, drop the old connection 1069 * and start over if the sequence numbers 1070 * are above the previous ones. 1071 */ 1072 if ((tiflags & TH_SYN) && 1073 SEQ_GT(th->th_seq, vp->rcv_nxt)) { 1074 /* 1075 * We only support this in the !NOFDREF case, which 1076 * is to say: not here. 1077 */ 1078 goto dropwithreset; 1079 } 1080 1081 /* 1082 * If window is closed can only take segments at 1083 * window edge, and have to drop data and PUSH from 1084 * incoming segments. Continue processing, but 1085 * remember to ack. Otherwise, drop segment 1086 * and (if not RST) ack. 1087 */ 1088 if (vp->rcv_wnd == 0 && th->th_seq == vp->rcv_nxt) { 1089 t_flags |= TF_ACKNOW; 1090 TCP_STATINC(TCP_STAT_RCVWINPROBE); 1091 } else { 1092 goto dropafterack; 1093 } 1094 } else { 1095 TCP_STATADD(TCP_STAT_RCVBYTEAFTERWIN, todrop); 1096 } 1097 m_adj(m, -todrop); 1098 tlen -= todrop; 1099 tiflags &= ~(TH_PUSH|TH_FIN); 1100 } 1101 1102 if (tiflags & TH_RST) { 1103 if (th->th_seq != vp->rcv_nxt) 1104 goto dropafterack_ratelim; 1105 1106 vtw_del(vp->ctl, vp->vtw); 1107 goto drop; 1108 } 1109 1110 /* 1111 * If the ACK bit is off we drop the segment and return. 1112 */ 1113 if ((tiflags & TH_ACK) == 0) { 1114 if (t_flags & TF_ACKNOW) 1115 goto dropafterack; 1116 goto drop; 1117 } 1118 1119 /* 1120 * In TIME_WAIT state the only thing that should arrive 1121 * is a retransmission of the remote FIN. Acknowledge 1122 * it and restart the finack timer. 1123 */ 1124 vtw_restart(vp); 1125 goto dropafterack; 1126 1127 dropafterack: 1128 /* 1129 * Generate an ACK dropping incoming segment if it occupies 1130 * sequence space, where the ACK reflects our state. 1131 */ 1132 if (tiflags & TH_RST) 1133 goto drop; 1134 goto dropafterack2; 1135 1136 dropafterack_ratelim: 1137 /* 1138 * We may want to rate-limit ACKs against SYN/RST attack. 1139 */ 1140 if (ppsratecheck(&tcp_ackdrop_ppslim_last, &tcp_ackdrop_ppslim_count, 1141 tcp_ackdrop_ppslim) == 0) { 1142 /* XXX stat */ 1143 goto drop; 1144 } 1145 /* ...fall into dropafterack2... */ 1146 1147 dropafterack2: 1148 (void)tcp_respond(0, m, m, th, th->th_seq + tlen, th->th_ack, TH_ACK); 1149 return; 1150 1151 dropwithreset: 1152 /* 1153 * Generate a RST, dropping incoming segment. 1154 * Make ACK acceptable to originator of segment. 1155 */ 1156 if (tiflags & TH_RST) 1157 goto drop; 1158 1159 if (tiflags & TH_ACK) { 1160 tcp_respond(0, m, m, th, (tcp_seq)0, th->th_ack, TH_RST); 1161 } else { 1162 if (tiflags & TH_SYN) 1163 ++tlen; 1164 (void)tcp_respond(0, m, m, th, th->th_seq + tlen, (tcp_seq)0, 1165 TH_RST|TH_ACK); 1166 } 1167 return; 1168 drop: 1169 m_freem(m); 1170 } 1171 1172 /* 1173 * TCP input routine, follows pages 65-76 of RFC 793 very closely. 1174 */ 1175 void 1176 tcp_input(struct mbuf *m, ...) 1177 { 1178 struct tcphdr *th; 1179 struct ip *ip; 1180 struct inpcb *inp; 1181 #ifdef INET6 1182 struct ip6_hdr *ip6; 1183 struct in6pcb *in6p; 1184 #endif 1185 u_int8_t *optp = NULL; 1186 int optlen = 0; 1187 int len, tlen, toff, hdroptlen = 0; 1188 struct tcpcb *tp = NULL; 1189 int tiflags; 1190 struct socket *so = NULL; 1191 int todrop, acked, ourfinisacked, needoutput = 0; 1192 bool dupseg; 1193 #ifdef TCP_DEBUG 1194 short ostate = 0; 1195 #endif 1196 u_long tiwin; 1197 struct tcp_opt_info opti; 1198 int off, iphlen; 1199 va_list ap; 1200 int af; /* af on the wire */ 1201 struct mbuf *tcp_saveti = NULL; 1202 uint32_t ts_rtt; 1203 uint8_t iptos; 1204 uint64_t *tcps; 1205 vestigial_inpcb_t vestige; 1206 1207 vestige.valid = 0; 1208 1209 MCLAIM(m, &tcp_rx_mowner); 1210 va_start(ap, m); 1211 toff = va_arg(ap, int); 1212 (void)va_arg(ap, int); /* ignore value, advance ap */ 1213 va_end(ap); 1214 1215 TCP_STATINC(TCP_STAT_RCVTOTAL); 1216 1217 memset(&opti, 0, sizeof(opti)); 1218 opti.ts_present = 0; 1219 opti.maxseg = 0; 1220 1221 /* 1222 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN. 1223 * 1224 * TCP is, by definition, unicast, so we reject all 1225 * multicast outright. 1226 * 1227 * Note, there are additional src/dst address checks in 1228 * the AF-specific code below. 1229 */ 1230 if (m->m_flags & (M_BCAST|M_MCAST)) { 1231 /* XXX stat */ 1232 goto drop; 1233 } 1234 #ifdef INET6 1235 if (m->m_flags & M_ANYCAST6) { 1236 /* XXX stat */ 1237 goto drop; 1238 } 1239 #endif 1240 1241 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, sizeof(struct tcphdr)); 1242 if (th == NULL) { 1243 TCP_STATINC(TCP_STAT_RCVSHORT); 1244 return; 1245 } 1246 1247 /* 1248 * Get IP and TCP header. 1249 * Note: IP leaves IP header in first mbuf. 1250 */ 1251 ip = mtod(m, struct ip *); 1252 switch (ip->ip_v) { 1253 case 4: 1254 #ifdef INET6 1255 ip6 = NULL; 1256 #endif 1257 af = AF_INET; 1258 iphlen = sizeof(struct ip); 1259 1260 if (IN_MULTICAST(ip->ip_dst.s_addr) || 1261 in_broadcast(ip->ip_dst, m_get_rcvif_NOMPSAFE(m))) 1262 goto drop; 1263 1264 /* We do the checksum after PCB lookup... */ 1265 len = ntohs(ip->ip_len); 1266 tlen = len - toff; 1267 iptos = ip->ip_tos; 1268 break; 1269 #ifdef INET6 1270 case 6: 1271 ip = NULL; 1272 iphlen = sizeof(struct ip6_hdr); 1273 af = AF_INET6; 1274 ip6 = mtod(m, struct ip6_hdr *); 1275 1276 /* 1277 * Be proactive about unspecified IPv6 address in source. 1278 * As we use all-zero to indicate unbounded/unconnected pcb, 1279 * unspecified IPv6 address can be used to confuse us. 1280 * 1281 * Note that packets with unspecified IPv6 destination is 1282 * already dropped in ip6_input. 1283 */ 1284 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 1285 /* XXX stat */ 1286 goto drop; 1287 } 1288 1289 /* 1290 * Make sure destination address is not multicast. 1291 * Source address checked in ip6_input(). 1292 */ 1293 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) { 1294 /* XXX stat */ 1295 goto drop; 1296 } 1297 1298 /* We do the checksum after PCB lookup... */ 1299 len = m->m_pkthdr.len; 1300 tlen = len - toff; 1301 iptos = (ntohl(ip6->ip6_flow) >> 20) & 0xff; 1302 break; 1303 #endif 1304 default: 1305 m_freem(m); 1306 return; 1307 } 1308 1309 /* 1310 * Enforce alignment requirements that are violated in 1311 * some cases, see kern/50766 for details. 1312 */ 1313 if (TCP_HDR_ALIGNED_P(th) == 0) { 1314 m = m_copyup(m, toff + sizeof(struct tcphdr), 0); 1315 if (m == NULL) { 1316 TCP_STATINC(TCP_STAT_RCVSHORT); 1317 return; 1318 } 1319 ip = mtod(m, struct ip *); 1320 #ifdef INET6 1321 ip6 = mtod(m, struct ip6_hdr *); 1322 #endif 1323 th = (struct tcphdr *)(mtod(m, char *) + toff); 1324 } 1325 KASSERT(TCP_HDR_ALIGNED_P(th)); 1326 1327 /* 1328 * Check that TCP offset makes sense, pull out TCP options and 1329 * adjust length. 1330 */ 1331 off = th->th_off << 2; 1332 if (off < sizeof(struct tcphdr) || off > tlen) { 1333 TCP_STATINC(TCP_STAT_RCVBADOFF); 1334 goto drop; 1335 } 1336 tlen -= off; 1337 1338 if (off > sizeof(struct tcphdr)) { 1339 IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, off); 1340 if (th == NULL) { 1341 TCP_STATINC(TCP_STAT_RCVSHORT); 1342 return; 1343 } 1344 KASSERT(TCP_HDR_ALIGNED_P(th)); 1345 optlen = off - sizeof(struct tcphdr); 1346 optp = ((u_int8_t *)th) + sizeof(struct tcphdr); 1347 1348 /* 1349 * Do quick retrieval of timestamp options. 1350 * 1351 * If timestamp is the only option and it's formatted as 1352 * recommended in RFC 1323 appendix A, we quickly get the 1353 * values now and don't bother calling tcp_dooptions(), 1354 * etc. 1355 */ 1356 if ((optlen == TCPOLEN_TSTAMP_APPA || 1357 (optlen > TCPOLEN_TSTAMP_APPA && 1358 optp[TCPOLEN_TSTAMP_APPA] == TCPOPT_EOL)) && 1359 *(u_int32_t *)optp == htonl(TCPOPT_TSTAMP_HDR) && 1360 (th->th_flags & TH_SYN) == 0) { 1361 opti.ts_present = 1; 1362 opti.ts_val = ntohl(*(u_int32_t *)(optp + 4)); 1363 opti.ts_ecr = ntohl(*(u_int32_t *)(optp + 8)); 1364 optp = NULL; /* we've parsed the options */ 1365 } 1366 } 1367 tiflags = th->th_flags; 1368 1369 /* 1370 * Checksum extended TCP header and data 1371 */ 1372 if (tcp_input_checksum(af, m, th, toff, off, tlen)) 1373 goto badcsum; 1374 1375 /* 1376 * Locate pcb for segment. 1377 */ 1378 findpcb: 1379 inp = NULL; 1380 #ifdef INET6 1381 in6p = NULL; 1382 #endif 1383 switch (af) { 1384 case AF_INET: 1385 inp = in_pcblookup_connect(&tcbtable, ip->ip_src, th->th_sport, 1386 ip->ip_dst, th->th_dport, &vestige); 1387 if (inp == NULL && !vestige.valid) { 1388 TCP_STATINC(TCP_STAT_PCBHASHMISS); 1389 inp = in_pcblookup_bind(&tcbtable, ip->ip_dst, 1390 th->th_dport); 1391 } 1392 #ifdef INET6 1393 if (inp == NULL && !vestige.valid) { 1394 struct in6_addr s, d; 1395 1396 /* mapped addr case */ 1397 in6_in_2_v4mapin6(&ip->ip_src, &s); 1398 in6_in_2_v4mapin6(&ip->ip_dst, &d); 1399 in6p = in6_pcblookup_connect(&tcbtable, &s, 1400 th->th_sport, &d, th->th_dport, 0, &vestige); 1401 if (in6p == 0 && !vestige.valid) { 1402 TCP_STATINC(TCP_STAT_PCBHASHMISS); 1403 in6p = in6_pcblookup_bind(&tcbtable, &d, 1404 th->th_dport, 0); 1405 } 1406 } 1407 #endif 1408 #ifndef INET6 1409 if (inp == NULL && !vestige.valid) 1410 #else 1411 if (inp == NULL && in6p == NULL && !vestige.valid) 1412 #endif 1413 { 1414 TCP_STATINC(TCP_STAT_NOPORT); 1415 if (tcp_log_refused && 1416 (tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) { 1417 tcp4_log_refused(ip, th); 1418 } 1419 tcp_fields_to_host(th); 1420 goto dropwithreset_ratelim; 1421 } 1422 #if defined(IPSEC) 1423 if (ipsec_used) { 1424 if (inp && ipsec_in_reject(m, inp)) { 1425 goto drop; 1426 } 1427 #ifdef INET6 1428 else if (in6p && ipsec_in_reject(m, in6p)) { 1429 goto drop; 1430 } 1431 #endif 1432 } 1433 #endif /*IPSEC*/ 1434 break; 1435 #ifdef INET6 1436 case AF_INET6: 1437 { 1438 int faith; 1439 1440 #if defined(NFAITH) && NFAITH > 0 1441 faith = faithprefix(&ip6->ip6_dst); 1442 #else 1443 faith = 0; 1444 #endif 1445 in6p = in6_pcblookup_connect(&tcbtable, &ip6->ip6_src, 1446 th->th_sport, &ip6->ip6_dst, th->th_dport, faith, &vestige); 1447 if (!in6p && !vestige.valid) { 1448 TCP_STATINC(TCP_STAT_PCBHASHMISS); 1449 in6p = in6_pcblookup_bind(&tcbtable, &ip6->ip6_dst, 1450 th->th_dport, faith); 1451 } 1452 if (!in6p && !vestige.valid) { 1453 TCP_STATINC(TCP_STAT_NOPORT); 1454 if (tcp_log_refused && 1455 (tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) { 1456 tcp6_log_refused(ip6, th); 1457 } 1458 tcp_fields_to_host(th); 1459 goto dropwithreset_ratelim; 1460 } 1461 #if defined(IPSEC) 1462 if (ipsec_used && in6p && ipsec_in_reject(m, in6p)) { 1463 goto drop; 1464 } 1465 #endif 1466 break; 1467 } 1468 #endif 1469 } 1470 1471 tcp_fields_to_host(th); 1472 1473 /* 1474 * If the state is CLOSED (i.e., TCB does not exist) then 1475 * all data in the incoming segment is discarded. 1476 * If the TCB exists but is in CLOSED state, it is embryonic, 1477 * but should either do a listen or a connect soon. 1478 */ 1479 tp = NULL; 1480 so = NULL; 1481 if (inp) { 1482 /* Check the minimum TTL for socket. */ 1483 if (ip->ip_ttl < inp->inp_ip_minttl) 1484 goto drop; 1485 1486 tp = intotcpcb(inp); 1487 so = inp->inp_socket; 1488 } 1489 #ifdef INET6 1490 else if (in6p) { 1491 tp = in6totcpcb(in6p); 1492 so = in6p->in6p_socket; 1493 } 1494 #endif 1495 else if (vestige.valid) { 1496 /* We do not support the resurrection of vtw tcpcps. */ 1497 tcp_vtw_input(th, &vestige, m, tlen); 1498 m = NULL; 1499 goto drop; 1500 } 1501 1502 if (tp == NULL) 1503 goto dropwithreset_ratelim; 1504 if (tp->t_state == TCPS_CLOSED) 1505 goto drop; 1506 1507 KASSERT(so->so_lock == softnet_lock); 1508 KASSERT(solocked(so)); 1509 1510 /* Unscale the window into a 32-bit value. */ 1511 if ((tiflags & TH_SYN) == 0) 1512 tiwin = th->th_win << tp->snd_scale; 1513 else 1514 tiwin = th->th_win; 1515 1516 #ifdef INET6 1517 /* save packet options if user wanted */ 1518 if (in6p && (in6p->in6p_flags & IN6P_CONTROLOPTS)) { 1519 if (in6p->in6p_options) { 1520 m_freem(in6p->in6p_options); 1521 in6p->in6p_options = NULL; 1522 } 1523 KASSERT(ip6 != NULL); 1524 ip6_savecontrol(in6p, &in6p->in6p_options, ip6, m); 1525 } 1526 #endif 1527 1528 if (so->so_options & SO_DEBUG) { 1529 #ifdef TCP_DEBUG 1530 ostate = tp->t_state; 1531 #endif 1532 1533 tcp_saveti = NULL; 1534 if (iphlen + sizeof(struct tcphdr) > MHLEN) 1535 goto nosave; 1536 1537 if (m->m_len > iphlen && (m->m_flags & M_EXT) == 0) { 1538 tcp_saveti = m_copym(m, 0, iphlen, M_DONTWAIT); 1539 if (tcp_saveti == NULL) 1540 goto nosave; 1541 } else { 1542 MGETHDR(tcp_saveti, M_DONTWAIT, MT_HEADER); 1543 if (tcp_saveti == NULL) 1544 goto nosave; 1545 MCLAIM(m, &tcp_mowner); 1546 tcp_saveti->m_len = iphlen; 1547 m_copydata(m, 0, iphlen, 1548 mtod(tcp_saveti, void *)); 1549 } 1550 1551 if (M_TRAILINGSPACE(tcp_saveti) < sizeof(struct tcphdr)) { 1552 m_freem(tcp_saveti); 1553 tcp_saveti = NULL; 1554 } else { 1555 tcp_saveti->m_len += sizeof(struct tcphdr); 1556 memcpy(mtod(tcp_saveti, char *) + iphlen, th, 1557 sizeof(struct tcphdr)); 1558 } 1559 nosave:; 1560 } 1561 1562 if (so->so_options & SO_ACCEPTCONN) { 1563 union syn_cache_sa src; 1564 union syn_cache_sa dst; 1565 1566 KASSERT(tp->t_state == TCPS_LISTEN); 1567 1568 memset(&src, 0, sizeof(src)); 1569 memset(&dst, 0, sizeof(dst)); 1570 switch (af) { 1571 case AF_INET: 1572 src.sin.sin_len = sizeof(struct sockaddr_in); 1573 src.sin.sin_family = AF_INET; 1574 src.sin.sin_addr = ip->ip_src; 1575 src.sin.sin_port = th->th_sport; 1576 1577 dst.sin.sin_len = sizeof(struct sockaddr_in); 1578 dst.sin.sin_family = AF_INET; 1579 dst.sin.sin_addr = ip->ip_dst; 1580 dst.sin.sin_port = th->th_dport; 1581 break; 1582 #ifdef INET6 1583 case AF_INET6: 1584 src.sin6.sin6_len = sizeof(struct sockaddr_in6); 1585 src.sin6.sin6_family = AF_INET6; 1586 src.sin6.sin6_addr = ip6->ip6_src; 1587 src.sin6.sin6_port = th->th_sport; 1588 1589 dst.sin6.sin6_len = sizeof(struct sockaddr_in6); 1590 dst.sin6.sin6_family = AF_INET6; 1591 dst.sin6.sin6_addr = ip6->ip6_dst; 1592 dst.sin6.sin6_port = th->th_dport; 1593 break; 1594 #endif 1595 } 1596 1597 if ((tiflags & (TH_RST|TH_ACK|TH_SYN)) != TH_SYN) { 1598 if (tiflags & TH_RST) { 1599 syn_cache_reset(&src.sa, &dst.sa, th); 1600 } else if ((tiflags & (TH_ACK|TH_SYN)) == 1601 (TH_ACK|TH_SYN)) { 1602 /* 1603 * Received a SYN,ACK. This should never 1604 * happen while we are in LISTEN. Send an RST. 1605 */ 1606 goto badsyn; 1607 } else if (tiflags & TH_ACK) { 1608 so = syn_cache_get(&src.sa, &dst.sa, th, so, m); 1609 if (so == NULL) { 1610 /* 1611 * We don't have a SYN for this ACK; 1612 * send an RST. 1613 */ 1614 goto badsyn; 1615 } else if (so == (struct socket *)(-1)) { 1616 /* 1617 * We were unable to create the 1618 * connection. If the 3-way handshake 1619 * was completed, and RST has been 1620 * sent to the peer. Since the mbuf 1621 * might be in use for the reply, do 1622 * not free it. 1623 */ 1624 m = NULL; 1625 } else { 1626 /* 1627 * We have created a full-blown 1628 * connection. 1629 */ 1630 tp = NULL; 1631 inp = NULL; 1632 #ifdef INET6 1633 in6p = NULL; 1634 #endif 1635 switch (so->so_proto->pr_domain->dom_family) { 1636 case AF_INET: 1637 inp = sotoinpcb(so); 1638 tp = intotcpcb(inp); 1639 break; 1640 #ifdef INET6 1641 case AF_INET6: 1642 in6p = sotoin6pcb(so); 1643 tp = in6totcpcb(in6p); 1644 break; 1645 #endif 1646 } 1647 if (tp == NULL) 1648 goto badsyn; /*XXX*/ 1649 tiwin <<= tp->snd_scale; 1650 goto after_listen; 1651 } 1652 } else { 1653 /* 1654 * None of RST, SYN or ACK was set. 1655 * This is an invalid packet for a 1656 * TCB in LISTEN state. Send a RST. 1657 */ 1658 goto badsyn; 1659 } 1660 } else { 1661 /* 1662 * Received a SYN. 1663 */ 1664 1665 #ifdef INET6 1666 /* 1667 * If deprecated address is forbidden, we do 1668 * not accept SYN to deprecated interface 1669 * address to prevent any new inbound 1670 * connection from getting established. 1671 * When we do not accept SYN, we send a TCP 1672 * RST, with deprecated source address (instead 1673 * of dropping it). We compromise it as it is 1674 * much better for peer to send a RST, and 1675 * RST will be the final packet for the 1676 * exchange. 1677 * 1678 * If we do not forbid deprecated addresses, we 1679 * accept the SYN packet. RFC2462 does not 1680 * suggest dropping SYN in this case. 1681 * If we decipher RFC2462 5.5.4, it says like 1682 * this: 1683 * 1. use of deprecated addr with existing 1684 * communication is okay - "SHOULD continue 1685 * to be used" 1686 * 2. use of it with new communication: 1687 * (2a) "SHOULD NOT be used if alternate 1688 * address with sufficient scope is 1689 * available" 1690 * (2b) nothing mentioned otherwise. 1691 * Here we fall into (2b) case as we have no 1692 * choice in our source address selection - we 1693 * must obey the peer. 1694 * 1695 * The wording in RFC2462 is confusing, and 1696 * there are multiple description text for 1697 * deprecated address handling - worse, they 1698 * are not exactly the same. I believe 5.5.4 1699 * is the best one, so we follow 5.5.4. 1700 */ 1701 if (af == AF_INET6 && !ip6_use_deprecated) { 1702 struct in6_ifaddr *ia6; 1703 int s; 1704 struct ifnet *rcvif = m_get_rcvif(m, &s); 1705 if (rcvif == NULL) 1706 goto dropwithreset; /* XXX */ 1707 if ((ia6 = in6ifa_ifpwithaddr(rcvif, 1708 &ip6->ip6_dst)) && 1709 (ia6->ia6_flags & IN6_IFF_DEPRECATED)) { 1710 tp = NULL; 1711 m_put_rcvif(rcvif, &s); 1712 goto dropwithreset; 1713 } 1714 m_put_rcvif(rcvif, &s); 1715 } 1716 #endif 1717 1718 /* 1719 * LISTEN socket received a SYN from itself? This 1720 * can't possibly be valid; drop the packet. 1721 */ 1722 if (th->th_sport == th->th_dport) { 1723 int eq = 0; 1724 1725 switch (af) { 1726 case AF_INET: 1727 eq = in_hosteq(ip->ip_src, ip->ip_dst); 1728 break; 1729 #ifdef INET6 1730 case AF_INET6: 1731 eq = IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, 1732 &ip6->ip6_dst); 1733 break; 1734 #endif 1735 } 1736 if (eq) { 1737 TCP_STATINC(TCP_STAT_BADSYN); 1738 goto drop; 1739 } 1740 } 1741 1742 /* 1743 * SYN looks ok; create compressed TCP 1744 * state for it. 1745 */ 1746 if (so->so_qlen <= so->so_qlimit && 1747 syn_cache_add(&src.sa, &dst.sa, th, toff, 1748 so, m, optp, optlen, &opti)) 1749 m = NULL; 1750 } 1751 1752 goto drop; 1753 } 1754 1755 after_listen: 1756 /* 1757 * From here on, we're dealing with !LISTEN. 1758 */ 1759 KASSERT(tp->t_state != TCPS_LISTEN); 1760 1761 /* 1762 * Segment received on connection. 1763 * Reset idle time and keep-alive timer. 1764 */ 1765 tp->t_rcvtime = tcp_now; 1766 if (TCPS_HAVEESTABLISHED(tp->t_state)) 1767 TCP_TIMER_ARM(tp, TCPT_KEEP, tp->t_keepidle); 1768 1769 /* 1770 * Process options. 1771 */ 1772 #ifdef TCP_SIGNATURE 1773 if (optp || (tp->t_flags & TF_SIGNATURE)) 1774 #else 1775 if (optp) 1776 #endif 1777 if (tcp_dooptions(tp, optp, optlen, th, m, toff, &opti) < 0) 1778 goto drop; 1779 1780 if (TCP_SACK_ENABLED(tp)) { 1781 tcp_del_sackholes(tp, th); 1782 } 1783 1784 if (TCP_ECN_ALLOWED(tp)) { 1785 if (tiflags & TH_CWR) { 1786 tp->t_flags &= ~TF_ECN_SND_ECE; 1787 } 1788 switch (iptos & IPTOS_ECN_MASK) { 1789 case IPTOS_ECN_CE: 1790 tp->t_flags |= TF_ECN_SND_ECE; 1791 TCP_STATINC(TCP_STAT_ECN_CE); 1792 break; 1793 case IPTOS_ECN_ECT0: 1794 TCP_STATINC(TCP_STAT_ECN_ECT); 1795 break; 1796 case IPTOS_ECN_ECT1: 1797 /* XXX: ignore for now -- rpaulo */ 1798 break; 1799 } 1800 /* 1801 * Congestion experienced. 1802 * Ignore if we are already trying to recover. 1803 */ 1804 if ((tiflags & TH_ECE) && SEQ_GEQ(tp->snd_una, tp->snd_recover)) 1805 tp->t_congctl->cong_exp(tp); 1806 } 1807 1808 if (opti.ts_present && opti.ts_ecr) { 1809 /* 1810 * Calculate the RTT from the returned time stamp and the 1811 * connection's time base. If the time stamp is later than 1812 * the current time, or is extremely old, fall back to non-1323 1813 * RTT calculation. Since ts_rtt is unsigned, we can test both 1814 * at the same time. 1815 * 1816 * Note that ts_rtt is in units of slow ticks (500 1817 * ms). Since most earthbound RTTs are < 500 ms, 1818 * observed values will have large quantization noise. 1819 * Our smoothed RTT is then the fraction of observed 1820 * samples that are 1 tick instead of 0 (times 500 1821 * ms). 1822 * 1823 * ts_rtt is increased by 1 to denote a valid sample, 1824 * with 0 indicating an invalid measurement. This 1825 * extra 1 must be removed when ts_rtt is used, or 1826 * else an an erroneous extra 500 ms will result. 1827 */ 1828 ts_rtt = TCP_TIMESTAMP(tp) - opti.ts_ecr + 1; 1829 if (ts_rtt > TCP_PAWS_IDLE) 1830 ts_rtt = 0; 1831 } else { 1832 ts_rtt = 0; 1833 } 1834 1835 /* 1836 * Fast path: check for the two common cases of a uni-directional 1837 * data transfer. If: 1838 * o We are in the ESTABLISHED state, and 1839 * o The packet has no control flags, and 1840 * o The packet is in-sequence, and 1841 * o The window didn't change, and 1842 * o We are not retransmitting 1843 * It's a candidate. 1844 * 1845 * If the length (tlen) is zero and the ack moved forward, we're 1846 * the sender side of the transfer. Just free the data acked and 1847 * wake any higher level process that was blocked waiting for 1848 * space. 1849 * 1850 * If the length is non-zero and the ack didn't move, we're the 1851 * receiver side. If we're getting packets in-order (the reassembly 1852 * queue is empty), add the data to the socket buffer and note 1853 * that we need a delayed ack. 1854 */ 1855 if (tp->t_state == TCPS_ESTABLISHED && 1856 (tiflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ECE|TH_CWR|TH_ACK)) 1857 == TH_ACK && 1858 (!opti.ts_present || TSTMP_GEQ(opti.ts_val, tp->ts_recent)) && 1859 th->th_seq == tp->rcv_nxt && 1860 tiwin && tiwin == tp->snd_wnd && 1861 tp->snd_nxt == tp->snd_max) { 1862 1863 /* 1864 * If last ACK falls within this segment's sequence numbers, 1865 * record the timestamp. 1866 * NOTE that the test is modified according to the latest 1867 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 1868 * 1869 * note that we already know 1870 * TSTMP_GEQ(opti.ts_val, tp->ts_recent) 1871 */ 1872 if (opti.ts_present && SEQ_LEQ(th->th_seq, tp->last_ack_sent)) { 1873 tp->ts_recent_age = tcp_now; 1874 tp->ts_recent = opti.ts_val; 1875 } 1876 1877 if (tlen == 0) { 1878 /* Ack prediction. */ 1879 if (SEQ_GT(th->th_ack, tp->snd_una) && 1880 SEQ_LEQ(th->th_ack, tp->snd_max) && 1881 tp->snd_cwnd >= tp->snd_wnd && 1882 tp->t_partialacks < 0) { 1883 /* 1884 * this is a pure ack for outstanding data. 1885 */ 1886 if (ts_rtt) 1887 tcp_xmit_timer(tp, ts_rtt - 1); 1888 else if (tp->t_rtttime && 1889 SEQ_GT(th->th_ack, tp->t_rtseq)) 1890 tcp_xmit_timer(tp, 1891 tcp_now - tp->t_rtttime); 1892 acked = th->th_ack - tp->snd_una; 1893 tcps = TCP_STAT_GETREF(); 1894 tcps[TCP_STAT_PREDACK]++; 1895 tcps[TCP_STAT_RCVACKPACK]++; 1896 tcps[TCP_STAT_RCVACKBYTE] += acked; 1897 TCP_STAT_PUTREF(); 1898 nd6_hint(tp); 1899 1900 if (acked > (tp->t_lastoff - tp->t_inoff)) 1901 tp->t_lastm = NULL; 1902 sbdrop(&so->so_snd, acked); 1903 tp->t_lastoff -= acked; 1904 1905 icmp_check(tp, th, acked); 1906 1907 tp->snd_una = th->th_ack; 1908 tp->snd_fack = tp->snd_una; 1909 if (SEQ_LT(tp->snd_high, tp->snd_una)) 1910 tp->snd_high = tp->snd_una; 1911 m_freem(m); 1912 1913 /* 1914 * If all outstanding data are acked, stop 1915 * retransmit timer, otherwise restart timer 1916 * using current (possibly backed-off) value. 1917 * If process is waiting for space, 1918 * wakeup/selnotify/signal. If data 1919 * are ready to send, let tcp_output 1920 * decide between more output or persist. 1921 */ 1922 if (tp->snd_una == tp->snd_max) 1923 TCP_TIMER_DISARM(tp, TCPT_REXMT); 1924 else if (TCP_TIMER_ISARMED(tp, 1925 TCPT_PERSIST) == 0) 1926 TCP_TIMER_ARM(tp, TCPT_REXMT, 1927 tp->t_rxtcur); 1928 1929 sowwakeup(so); 1930 if (so->so_snd.sb_cc) { 1931 KERNEL_LOCK(1, NULL); 1932 (void)tcp_output(tp); 1933 KERNEL_UNLOCK_ONE(NULL); 1934 } 1935 if (tcp_saveti) 1936 m_freem(tcp_saveti); 1937 return; 1938 } 1939 } else if (th->th_ack == tp->snd_una && 1940 TAILQ_FIRST(&tp->segq) == NULL && 1941 tlen <= sbspace(&so->so_rcv)) { 1942 int newsize = 0; 1943 1944 /* 1945 * this is a pure, in-sequence data packet 1946 * with nothing on the reassembly queue and 1947 * we have enough buffer space to take it. 1948 */ 1949 tp->rcv_nxt += tlen; 1950 tcps = TCP_STAT_GETREF(); 1951 tcps[TCP_STAT_PREDDAT]++; 1952 tcps[TCP_STAT_RCVPACK]++; 1953 tcps[TCP_STAT_RCVBYTE] += tlen; 1954 TCP_STAT_PUTREF(); 1955 nd6_hint(tp); 1956 1957 /* 1958 * Automatic sizing enables the performance of large buffers 1959 * and most of the efficiency of small ones by only allocating 1960 * space when it is needed. 1961 * 1962 * On the receive side the socket buffer memory is only rarely 1963 * used to any significant extent. This allows us to be much 1964 * more aggressive in scaling the receive socket buffer. For 1965 * the case that the buffer space is actually used to a large 1966 * extent and we run out of kernel memory we can simply drop 1967 * the new segments; TCP on the sender will just retransmit it 1968 * later. Setting the buffer size too big may only consume too 1969 * much kernel memory if the application doesn't read() from 1970 * the socket or packet loss or reordering makes use of the 1971 * reassembly queue. 1972 * 1973 * The criteria to step up the receive buffer one notch are: 1974 * 1. the number of bytes received during the time it takes 1975 * one timestamp to be reflected back to us (the RTT); 1976 * 2. received bytes per RTT is within seven eighth of the 1977 * current socket buffer size; 1978 * 3. receive buffer size has not hit maximal automatic size; 1979 * 1980 * This algorithm does one step per RTT at most and only if 1981 * we receive a bulk stream w/o packet losses or reorderings. 1982 * Shrinking the buffer during idle times is not necessary as 1983 * it doesn't consume any memory when idle. 1984 * 1985 * TODO: Only step up if the application is actually serving 1986 * the buffer to better manage the socket buffer resources. 1987 */ 1988 if (tcp_do_autorcvbuf && 1989 opti.ts_ecr && 1990 (so->so_rcv.sb_flags & SB_AUTOSIZE)) { 1991 if (opti.ts_ecr > tp->rfbuf_ts && 1992 opti.ts_ecr - tp->rfbuf_ts < PR_SLOWHZ) { 1993 if (tp->rfbuf_cnt > 1994 (so->so_rcv.sb_hiwat / 8 * 7) && 1995 so->so_rcv.sb_hiwat < 1996 tcp_autorcvbuf_max) { 1997 newsize = 1998 min(so->so_rcv.sb_hiwat + 1999 tcp_autorcvbuf_inc, 2000 tcp_autorcvbuf_max); 2001 } 2002 /* Start over with next RTT. */ 2003 tp->rfbuf_ts = 0; 2004 tp->rfbuf_cnt = 0; 2005 } else 2006 tp->rfbuf_cnt += tlen; /* add up */ 2007 } 2008 2009 /* 2010 * Drop TCP, IP headers and TCP options then add data 2011 * to socket buffer. 2012 */ 2013 if (so->so_state & SS_CANTRCVMORE) { 2014 m_freem(m); 2015 } else { 2016 /* 2017 * Set new socket buffer size. 2018 * Give up when limit is reached. 2019 */ 2020 if (newsize) 2021 if (!sbreserve(&so->so_rcv, 2022 newsize, so)) 2023 so->so_rcv.sb_flags &= ~SB_AUTOSIZE; 2024 m_adj(m, toff + off); 2025 sbappendstream(&so->so_rcv, m); 2026 } 2027 sorwakeup(so); 2028 tcp_setup_ack(tp, th); 2029 if (tp->t_flags & TF_ACKNOW) { 2030 KERNEL_LOCK(1, NULL); 2031 (void)tcp_output(tp); 2032 KERNEL_UNLOCK_ONE(NULL); 2033 } 2034 if (tcp_saveti) 2035 m_freem(tcp_saveti); 2036 return; 2037 } 2038 } 2039 2040 /* 2041 * Compute mbuf offset to TCP data segment. 2042 */ 2043 hdroptlen = toff + off; 2044 2045 /* 2046 * Calculate amount of space in receive window. Receive window is 2047 * amount of space in rcv queue, but not less than advertised 2048 * window. 2049 */ 2050 { 2051 int win; 2052 win = sbspace(&so->so_rcv); 2053 if (win < 0) 2054 win = 0; 2055 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 2056 } 2057 2058 /* Reset receive buffer auto scaling when not in bulk receive mode. */ 2059 tp->rfbuf_ts = 0; 2060 tp->rfbuf_cnt = 0; 2061 2062 switch (tp->t_state) { 2063 /* 2064 * If the state is SYN_SENT: 2065 * if seg contains an ACK, but not for our SYN, drop the input. 2066 * if seg contains a RST, then drop the connection. 2067 * if seg does not contain SYN, then drop it. 2068 * Otherwise this is an acceptable SYN segment 2069 * initialize tp->rcv_nxt and tp->irs 2070 * if seg contains ack then advance tp->snd_una 2071 * if seg contains a ECE and ECN support is enabled, the stream 2072 * is ECN capable. 2073 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 2074 * arrange for segment to be acked (eventually) 2075 * continue processing rest of data/controls, beginning with URG 2076 */ 2077 case TCPS_SYN_SENT: 2078 if ((tiflags & TH_ACK) && 2079 (SEQ_LEQ(th->th_ack, tp->iss) || 2080 SEQ_GT(th->th_ack, tp->snd_max))) 2081 goto dropwithreset; 2082 if (tiflags & TH_RST) { 2083 if (tiflags & TH_ACK) 2084 tp = tcp_drop(tp, ECONNREFUSED); 2085 goto drop; 2086 } 2087 if ((tiflags & TH_SYN) == 0) 2088 goto drop; 2089 if (tiflags & TH_ACK) { 2090 tp->snd_una = th->th_ack; 2091 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2092 tp->snd_nxt = tp->snd_una; 2093 if (SEQ_LT(tp->snd_high, tp->snd_una)) 2094 tp->snd_high = tp->snd_una; 2095 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2096 2097 if ((tiflags & TH_ECE) && tcp_do_ecn) { 2098 tp->t_flags |= TF_ECN_PERMIT; 2099 TCP_STATINC(TCP_STAT_ECN_SHS); 2100 } 2101 } 2102 tp->irs = th->th_seq; 2103 tcp_rcvseqinit(tp); 2104 tp->t_flags |= TF_ACKNOW; 2105 tcp_mss_from_peer(tp, opti.maxseg); 2106 2107 /* 2108 * Initialize the initial congestion window. If we 2109 * had to retransmit the SYN, we must initialize cwnd 2110 * to 1 segment (i.e. the Loss Window). 2111 */ 2112 if (tp->t_flags & TF_SYN_REXMT) 2113 tp->snd_cwnd = tp->t_peermss; 2114 else { 2115 int ss = tcp_init_win; 2116 if (inp != NULL && in_localaddr(inp->inp_faddr)) 2117 ss = tcp_init_win_local; 2118 #ifdef INET6 2119 if (in6p != NULL && in6_localaddr(&in6p->in6p_faddr)) 2120 ss = tcp_init_win_local; 2121 #endif 2122 tp->snd_cwnd = TCP_INITIAL_WINDOW(ss, tp->t_peermss); 2123 } 2124 2125 tcp_rmx_rtt(tp); 2126 if (tiflags & TH_ACK) { 2127 TCP_STATINC(TCP_STAT_CONNECTS); 2128 /* 2129 * move tcp_established before soisconnected 2130 * because upcall handler can drive tcp_output 2131 * functionality. 2132 * XXX we might call soisconnected at the end of 2133 * all processing 2134 */ 2135 tcp_established(tp); 2136 soisconnected(so); 2137 /* Do window scaling on this connection? */ 2138 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2139 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2140 tp->snd_scale = tp->requested_s_scale; 2141 tp->rcv_scale = tp->request_r_scale; 2142 } 2143 TCP_REASS_LOCK(tp); 2144 (void)tcp_reass(tp, NULL, NULL, tlen); 2145 /* 2146 * if we didn't have to retransmit the SYN, 2147 * use its rtt as our initial srtt & rtt var. 2148 */ 2149 if (tp->t_rtttime) 2150 tcp_xmit_timer(tp, tcp_now - tp->t_rtttime); 2151 } else { 2152 tp->t_state = TCPS_SYN_RECEIVED; 2153 } 2154 2155 /* 2156 * Advance th->th_seq to correspond to first data byte. 2157 * If data, trim to stay within window, 2158 * dropping FIN if necessary. 2159 */ 2160 th->th_seq++; 2161 if (tlen > tp->rcv_wnd) { 2162 todrop = tlen - tp->rcv_wnd; 2163 m_adj(m, -todrop); 2164 tlen = tp->rcv_wnd; 2165 tiflags &= ~TH_FIN; 2166 tcps = TCP_STAT_GETREF(); 2167 tcps[TCP_STAT_RCVPACKAFTERWIN]++; 2168 tcps[TCP_STAT_RCVBYTEAFTERWIN] += todrop; 2169 TCP_STAT_PUTREF(); 2170 } 2171 tp->snd_wl1 = th->th_seq - 1; 2172 tp->rcv_up = th->th_seq; 2173 goto step6; 2174 2175 /* 2176 * If the state is SYN_RECEIVED: 2177 * If seg contains an ACK, but not for our SYN, drop the input 2178 * and generate an RST. See page 36, rfc793 2179 */ 2180 case TCPS_SYN_RECEIVED: 2181 if ((tiflags & TH_ACK) && 2182 (SEQ_LEQ(th->th_ack, tp->iss) || 2183 SEQ_GT(th->th_ack, tp->snd_max))) 2184 goto dropwithreset; 2185 break; 2186 } 2187 2188 /* 2189 * From here on, we're dealing with !LISTEN and !SYN_SENT. 2190 */ 2191 KASSERT(tp->t_state != TCPS_LISTEN && 2192 tp->t_state != TCPS_SYN_SENT); 2193 2194 /* 2195 * RFC1323 PAWS: if we have a timestamp reply on this segment and 2196 * it's less than ts_recent, drop it. 2197 */ 2198 if (opti.ts_present && (tiflags & TH_RST) == 0 && tp->ts_recent && 2199 TSTMP_LT(opti.ts_val, tp->ts_recent)) { 2200 /* Check to see if ts_recent is over 24 days old. */ 2201 if (tcp_now - tp->ts_recent_age > TCP_PAWS_IDLE) { 2202 /* 2203 * Invalidate ts_recent. If this segment updates 2204 * ts_recent, the age will be reset later and ts_recent 2205 * will get a valid value. If it does not, setting 2206 * ts_recent to zero will at least satisfy the 2207 * requirement that zero be placed in the timestamp 2208 * echo reply when ts_recent isn't valid. The 2209 * age isn't reset until we get a valid ts_recent 2210 * because we don't want out-of-order segments to be 2211 * dropped when ts_recent is old. 2212 */ 2213 tp->ts_recent = 0; 2214 } else { 2215 tcps = TCP_STAT_GETREF(); 2216 tcps[TCP_STAT_RCVDUPPACK]++; 2217 tcps[TCP_STAT_RCVDUPBYTE] += tlen; 2218 tcps[TCP_STAT_PAWSDROP]++; 2219 TCP_STAT_PUTREF(); 2220 tcp_new_dsack(tp, th->th_seq, tlen); 2221 goto dropafterack; 2222 } 2223 } 2224 2225 /* 2226 * Check that at least some bytes of the segment are within the 2227 * receive window. If segment begins before rcv_nxt, drop leading 2228 * data (and SYN); if nothing left, just ack. 2229 */ 2230 todrop = tp->rcv_nxt - th->th_seq; 2231 dupseg = false; 2232 if (todrop > 0) { 2233 if (tiflags & TH_SYN) { 2234 tiflags &= ~TH_SYN; 2235 th->th_seq++; 2236 tcp_urp_drop(th, 1, &tiflags); 2237 todrop--; 2238 } 2239 if (todrop > tlen || 2240 (todrop == tlen && (tiflags & TH_FIN) == 0)) { 2241 /* 2242 * Any valid FIN or RST must be to the left of the 2243 * window. At this point the FIN or RST must be a 2244 * duplicate or out of sequence; drop it. 2245 */ 2246 if (tiflags & TH_RST) 2247 goto drop; 2248 tiflags &= ~(TH_FIN|TH_RST); 2249 2250 /* 2251 * Send an ACK to resynchronize and drop any data. 2252 * But keep on processing for RST or ACK. 2253 */ 2254 tp->t_flags |= TF_ACKNOW; 2255 todrop = tlen; 2256 dupseg = true; 2257 tcps = TCP_STAT_GETREF(); 2258 tcps[TCP_STAT_RCVDUPPACK]++; 2259 tcps[TCP_STAT_RCVDUPBYTE] += todrop; 2260 TCP_STAT_PUTREF(); 2261 } else if ((tiflags & TH_RST) && th->th_seq != tp->rcv_nxt) { 2262 /* 2263 * Test for reset before adjusting the sequence 2264 * number for overlapping data. 2265 */ 2266 goto dropafterack_ratelim; 2267 } else { 2268 tcps = TCP_STAT_GETREF(); 2269 tcps[TCP_STAT_RCVPARTDUPPACK]++; 2270 tcps[TCP_STAT_RCVPARTDUPBYTE] += todrop; 2271 TCP_STAT_PUTREF(); 2272 } 2273 tcp_new_dsack(tp, th->th_seq, todrop); 2274 hdroptlen += todrop; /* drop from head afterwards (m_adj) */ 2275 th->th_seq += todrop; 2276 tlen -= todrop; 2277 tcp_urp_drop(th, todrop, &tiflags); 2278 } 2279 2280 /* 2281 * If new data is received on a connection after the user processes 2282 * are gone, then RST the other end. 2283 */ 2284 if ((so->so_state & SS_NOFDREF) && 2285 tp->t_state > TCPS_CLOSE_WAIT && tlen) { 2286 tp = tcp_close(tp); 2287 TCP_STATINC(TCP_STAT_RCVAFTERCLOSE); 2288 goto dropwithreset; 2289 } 2290 2291 /* 2292 * If the segment ends after the window, drop trailing data (and 2293 * PUSH and FIN); if nothing left, just ACK. 2294 */ 2295 todrop = (th->th_seq + tlen) - (tp->rcv_nxt + tp->rcv_wnd); 2296 if (todrop > 0) { 2297 TCP_STATINC(TCP_STAT_RCVPACKAFTERWIN); 2298 if (todrop >= tlen) { 2299 /* 2300 * The segment actually starts after the window. 2301 * th->th_seq + tlen - tp->rcv_nxt - tp->rcv_wnd >= tlen 2302 * th->th_seq - tp->rcv_nxt - tp->rcv_wnd >= 0 2303 * th->th_seq >= tp->rcv_nxt + tp->rcv_wnd 2304 */ 2305 TCP_STATADD(TCP_STAT_RCVBYTEAFTERWIN, tlen); 2306 2307 /* 2308 * If a new connection request is received while in 2309 * TIME_WAIT, drop the old connection and start over 2310 * if the sequence numbers are above the previous 2311 * ones. 2312 * 2313 * NOTE: We need to put the header fields back into 2314 * network order. 2315 */ 2316 if ((tiflags & TH_SYN) && 2317 tp->t_state == TCPS_TIME_WAIT && 2318 SEQ_GT(th->th_seq, tp->rcv_nxt)) { 2319 tp = tcp_close(tp); 2320 tcp_fields_to_net(th); 2321 m_freem(tcp_saveti); 2322 tcp_saveti = NULL; 2323 goto findpcb; 2324 } 2325 2326 /* 2327 * If window is closed can only take segments at 2328 * window edge, and have to drop data and PUSH from 2329 * incoming segments. Continue processing, but 2330 * remember to ack. Otherwise, drop segment 2331 * and (if not RST) ack. 2332 */ 2333 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 2334 KASSERT(todrop == tlen); 2335 tp->t_flags |= TF_ACKNOW; 2336 TCP_STATINC(TCP_STAT_RCVWINPROBE); 2337 } else { 2338 goto dropafterack; 2339 } 2340 } else { 2341 TCP_STATADD(TCP_STAT_RCVBYTEAFTERWIN, todrop); 2342 } 2343 m_adj(m, -todrop); 2344 tlen -= todrop; 2345 tiflags &= ~(TH_PUSH|TH_FIN); 2346 } 2347 2348 /* 2349 * If last ACK falls within this segment's sequence numbers, 2350 * record the timestamp. 2351 * NOTE: 2352 * 1) That the test incorporates suggestions from the latest 2353 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 2354 * 2) That updating only on newer timestamps interferes with 2355 * our earlier PAWS tests, so this check should be solely 2356 * predicated on the sequence space of this segment. 2357 * 3) That we modify the segment boundary check to be 2358 * Last.ACK.Sent <= SEG.SEQ + SEG.Len 2359 * instead of RFC1323's 2360 * Last.ACK.Sent < SEG.SEQ + SEG.Len, 2361 * This modified check allows us to overcome RFC1323's 2362 * limitations as described in Stevens TCP/IP Illustrated 2363 * Vol. 2 p.869. In such cases, we can still calculate the 2364 * RTT correctly when RCV.NXT == Last.ACK.Sent. 2365 */ 2366 if (opti.ts_present && 2367 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 2368 SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen + 2369 ((tiflags & (TH_SYN|TH_FIN)) != 0))) { 2370 tp->ts_recent_age = tcp_now; 2371 tp->ts_recent = opti.ts_val; 2372 } 2373 2374 /* 2375 * If the RST bit is set examine the state: 2376 * RECEIVED state: 2377 * If passive open, return to LISTEN state. 2378 * If active open, inform user that connection was refused. 2379 * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT states: 2380 * Inform user that connection was reset, and close tcb. 2381 * CLOSING, LAST_ACK, TIME_WAIT states: 2382 * Close the tcb. 2383 */ 2384 if (tiflags & TH_RST) { 2385 if (th->th_seq != tp->rcv_nxt) 2386 goto dropafterack_ratelim; 2387 2388 switch (tp->t_state) { 2389 case TCPS_SYN_RECEIVED: 2390 so->so_error = ECONNREFUSED; 2391 goto close; 2392 2393 case TCPS_ESTABLISHED: 2394 case TCPS_FIN_WAIT_1: 2395 case TCPS_FIN_WAIT_2: 2396 case TCPS_CLOSE_WAIT: 2397 so->so_error = ECONNRESET; 2398 close: 2399 tp->t_state = TCPS_CLOSED; 2400 TCP_STATINC(TCP_STAT_DROPS); 2401 tp = tcp_close(tp); 2402 goto drop; 2403 2404 case TCPS_CLOSING: 2405 case TCPS_LAST_ACK: 2406 case TCPS_TIME_WAIT: 2407 tp = tcp_close(tp); 2408 goto drop; 2409 } 2410 } 2411 2412 /* 2413 * Since we've covered the SYN-SENT and SYN-RECEIVED states above 2414 * we must be in a synchronized state. RFC791 states (under RST 2415 * generation) that any unacceptable segment (an out-of-order SYN 2416 * qualifies) received in a synchronized state must elicit only an 2417 * empty acknowledgment segment ... and the connection remains in 2418 * the same state. 2419 */ 2420 if (tiflags & TH_SYN) { 2421 if (tp->rcv_nxt == th->th_seq) { 2422 tcp_respond(tp, m, m, th, (tcp_seq)0, th->th_ack - 1, 2423 TH_ACK); 2424 if (tcp_saveti) 2425 m_freem(tcp_saveti); 2426 return; 2427 } 2428 2429 goto dropafterack_ratelim; 2430 } 2431 2432 /* 2433 * If the ACK bit is off we drop the segment and return. 2434 */ 2435 if ((tiflags & TH_ACK) == 0) { 2436 if (tp->t_flags & TF_ACKNOW) 2437 goto dropafterack; 2438 goto drop; 2439 } 2440 2441 /* 2442 * From here on, we're doing ACK processing. 2443 */ 2444 2445 switch (tp->t_state) { 2446 /* 2447 * In SYN_RECEIVED state if the ack ACKs our SYN then enter 2448 * ESTABLISHED state and continue processing, otherwise 2449 * send an RST. 2450 */ 2451 case TCPS_SYN_RECEIVED: 2452 if (SEQ_GT(tp->snd_una, th->th_ack) || 2453 SEQ_GT(th->th_ack, tp->snd_max)) 2454 goto dropwithreset; 2455 TCP_STATINC(TCP_STAT_CONNECTS); 2456 soisconnected(so); 2457 tcp_established(tp); 2458 /* Do window scaling? */ 2459 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2460 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2461 tp->snd_scale = tp->requested_s_scale; 2462 tp->rcv_scale = tp->request_r_scale; 2463 } 2464 TCP_REASS_LOCK(tp); 2465 (void)tcp_reass(tp, NULL, NULL, tlen); 2466 tp->snd_wl1 = th->th_seq - 1; 2467 /* FALLTHROUGH */ 2468 2469 /* 2470 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 2471 * ACKs. If the ack is in the range 2472 * tp->snd_una < th->th_ack <= tp->snd_max 2473 * then advance tp->snd_una to th->th_ack and drop 2474 * data from the retransmission queue. If this ACK reflects 2475 * more up to date window information we update our window information. 2476 */ 2477 case TCPS_ESTABLISHED: 2478 case TCPS_FIN_WAIT_1: 2479 case TCPS_FIN_WAIT_2: 2480 case TCPS_CLOSE_WAIT: 2481 case TCPS_CLOSING: 2482 case TCPS_LAST_ACK: 2483 case TCPS_TIME_WAIT: 2484 if (SEQ_LEQ(th->th_ack, tp->snd_una)) { 2485 if (tlen == 0 && !dupseg && tiwin == tp->snd_wnd) { 2486 TCP_STATINC(TCP_STAT_RCVDUPACK); 2487 /* 2488 * If we have outstanding data (other than 2489 * a window probe), this is a completely 2490 * duplicate ack (ie, window info didn't 2491 * change), the ack is the biggest we've 2492 * seen and we've seen exactly our rexmt 2493 * threshhold of them, assume a packet 2494 * has been dropped and retransmit it. 2495 * Kludge snd_nxt & the congestion 2496 * window so we send only this one 2497 * packet. 2498 */ 2499 if (TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 || 2500 th->th_ack != tp->snd_una) 2501 tp->t_dupacks = 0; 2502 else if (tp->t_partialacks < 0 && 2503 (++tp->t_dupacks == tcprexmtthresh || 2504 TCP_FACK_FASTRECOV(tp))) { 2505 /* 2506 * Do the fast retransmit, and adjust 2507 * congestion control paramenters. 2508 */ 2509 if (tp->t_congctl->fast_retransmit(tp, th)) { 2510 /* False fast retransmit */ 2511 break; 2512 } 2513 goto drop; 2514 } else if (tp->t_dupacks > tcprexmtthresh) { 2515 tp->snd_cwnd += tp->t_segsz; 2516 KERNEL_LOCK(1, NULL); 2517 (void)tcp_output(tp); 2518 KERNEL_UNLOCK_ONE(NULL); 2519 goto drop; 2520 } 2521 } else { 2522 /* 2523 * If the ack appears to be very old, only 2524 * allow data that is in-sequence. This 2525 * makes it somewhat more difficult to insert 2526 * forged data by guessing sequence numbers. 2527 * Sent an ack to try to update the send 2528 * sequence number on the other side. 2529 */ 2530 if (tlen && th->th_seq != tp->rcv_nxt && 2531 SEQ_LT(th->th_ack, 2532 tp->snd_una - tp->max_sndwnd)) 2533 goto dropafterack; 2534 } 2535 break; 2536 } 2537 /* 2538 * If the congestion window was inflated to account 2539 * for the other side's cached packets, retract it. 2540 */ 2541 tp->t_congctl->fast_retransmit_newack(tp, th); 2542 2543 if (SEQ_GT(th->th_ack, tp->snd_max)) { 2544 TCP_STATINC(TCP_STAT_RCVACKTOOMUCH); 2545 goto dropafterack; 2546 } 2547 acked = th->th_ack - tp->snd_una; 2548 tcps = TCP_STAT_GETREF(); 2549 tcps[TCP_STAT_RCVACKPACK]++; 2550 tcps[TCP_STAT_RCVACKBYTE] += acked; 2551 TCP_STAT_PUTREF(); 2552 2553 /* 2554 * If we have a timestamp reply, update smoothed 2555 * round trip time. If no timestamp is present but 2556 * transmit timer is running and timed sequence 2557 * number was acked, update smoothed round trip time. 2558 * Since we now have an rtt measurement, cancel the 2559 * timer backoff (cf., Phil Karn's retransmit alg.). 2560 * Recompute the initial retransmit timer. 2561 */ 2562 if (ts_rtt) 2563 tcp_xmit_timer(tp, ts_rtt - 1); 2564 else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) 2565 tcp_xmit_timer(tp, tcp_now - tp->t_rtttime); 2566 2567 /* 2568 * If all outstanding data is acked, stop retransmit 2569 * timer and remember to restart (more output or persist). 2570 * If there is more data to be acked, restart retransmit 2571 * timer, using current (possibly backed-off) value. 2572 */ 2573 if (th->th_ack == tp->snd_max) { 2574 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2575 needoutput = 1; 2576 } else if (TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) 2577 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 2578 2579 /* 2580 * New data has been acked, adjust the congestion window. 2581 */ 2582 tp->t_congctl->newack(tp, th); 2583 2584 nd6_hint(tp); 2585 if (acked > so->so_snd.sb_cc) { 2586 tp->snd_wnd -= so->so_snd.sb_cc; 2587 sbdrop(&so->so_snd, (int)so->so_snd.sb_cc); 2588 ourfinisacked = 1; 2589 } else { 2590 if (acked > (tp->t_lastoff - tp->t_inoff)) 2591 tp->t_lastm = NULL; 2592 sbdrop(&so->so_snd, acked); 2593 tp->t_lastoff -= acked; 2594 if (tp->snd_wnd > acked) 2595 tp->snd_wnd -= acked; 2596 else 2597 tp->snd_wnd = 0; 2598 ourfinisacked = 0; 2599 } 2600 sowwakeup(so); 2601 2602 icmp_check(tp, th, acked); 2603 2604 tp->snd_una = th->th_ack; 2605 if (SEQ_GT(tp->snd_una, tp->snd_fack)) 2606 tp->snd_fack = tp->snd_una; 2607 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2608 tp->snd_nxt = tp->snd_una; 2609 if (SEQ_LT(tp->snd_high, tp->snd_una)) 2610 tp->snd_high = tp->snd_una; 2611 2612 switch (tp->t_state) { 2613 2614 /* 2615 * In FIN_WAIT_1 STATE in addition to the processing 2616 * for the ESTABLISHED state if our FIN is now acknowledged 2617 * then enter FIN_WAIT_2. 2618 */ 2619 case TCPS_FIN_WAIT_1: 2620 if (ourfinisacked) { 2621 /* 2622 * If we can't receive any more 2623 * data, then closing user can proceed. 2624 * Starting the timer is contrary to the 2625 * specification, but if we don't get a FIN 2626 * we'll hang forever. 2627 */ 2628 if (so->so_state & SS_CANTRCVMORE) { 2629 soisdisconnected(so); 2630 if (tp->t_maxidle > 0) 2631 TCP_TIMER_ARM(tp, TCPT_2MSL, 2632 tp->t_maxidle); 2633 } 2634 tp->t_state = TCPS_FIN_WAIT_2; 2635 } 2636 break; 2637 2638 /* 2639 * In CLOSING STATE in addition to the processing for 2640 * the ESTABLISHED state if the ACK acknowledges our FIN 2641 * then enter the TIME-WAIT state, otherwise ignore 2642 * the segment. 2643 */ 2644 case TCPS_CLOSING: 2645 if (ourfinisacked) { 2646 tp->t_state = TCPS_TIME_WAIT; 2647 tcp_canceltimers(tp); 2648 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * tp->t_msl); 2649 soisdisconnected(so); 2650 } 2651 break; 2652 2653 /* 2654 * In LAST_ACK, we may still be waiting for data to drain 2655 * and/or to be acked, as well as for the ack of our FIN. 2656 * If our FIN is now acknowledged, delete the TCB, 2657 * enter the closed state and return. 2658 */ 2659 case TCPS_LAST_ACK: 2660 if (ourfinisacked) { 2661 tp = tcp_close(tp); 2662 goto drop; 2663 } 2664 break; 2665 2666 /* 2667 * In TIME_WAIT state the only thing that should arrive 2668 * is a retransmission of the remote FIN. Acknowledge 2669 * it and restart the finack timer. 2670 */ 2671 case TCPS_TIME_WAIT: 2672 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * tp->t_msl); 2673 goto dropafterack; 2674 } 2675 } 2676 2677 step6: 2678 /* 2679 * Update window information. 2680 * Don't look at window if no ACK: TAC's send garbage on first SYN. 2681 */ 2682 if ((tiflags & TH_ACK) && (SEQ_LT(tp->snd_wl1, th->th_seq) || 2683 (tp->snd_wl1 == th->th_seq && (SEQ_LT(tp->snd_wl2, th->th_ack) || 2684 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))) { 2685 /* keep track of pure window updates */ 2686 if (tlen == 0 && 2687 tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) 2688 TCP_STATINC(TCP_STAT_RCVWINUPD); 2689 tp->snd_wnd = tiwin; 2690 tp->snd_wl1 = th->th_seq; 2691 tp->snd_wl2 = th->th_ack; 2692 if (tp->snd_wnd > tp->max_sndwnd) 2693 tp->max_sndwnd = tp->snd_wnd; 2694 needoutput = 1; 2695 } 2696 2697 /* 2698 * Process segments with URG. 2699 */ 2700 if ((tiflags & TH_URG) && th->th_urp && 2701 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2702 /* 2703 * This is a kludge, but if we receive and accept 2704 * random urgent pointers, we'll crash in 2705 * soreceive. It's hard to imagine someone 2706 * actually wanting to send this much urgent data. 2707 */ 2708 if (th->th_urp + so->so_rcv.sb_cc > sb_max) { 2709 th->th_urp = 0; /* XXX */ 2710 tiflags &= ~TH_URG; /* XXX */ 2711 goto dodata; /* XXX */ 2712 } 2713 2714 /* 2715 * If this segment advances the known urgent pointer, 2716 * then mark the data stream. This should not happen 2717 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 2718 * a FIN has been received from the remote side. 2719 * In these states we ignore the URG. 2720 * 2721 * According to RFC961 (Assigned Protocols), 2722 * the urgent pointer points to the last octet 2723 * of urgent data. We continue, however, 2724 * to consider it to indicate the first octet 2725 * of data past the urgent section as the original 2726 * spec states (in one of two places). 2727 */ 2728 if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) { 2729 tp->rcv_up = th->th_seq + th->th_urp; 2730 so->so_oobmark = so->so_rcv.sb_cc + 2731 (tp->rcv_up - tp->rcv_nxt) - 1; 2732 if (so->so_oobmark == 0) 2733 so->so_state |= SS_RCVATMARK; 2734 sohasoutofband(so); 2735 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); 2736 } 2737 2738 /* 2739 * Remove out of band data so doesn't get presented to user. 2740 * This can happen independent of advancing the URG pointer, 2741 * but if two URG's are pending at once, some out-of-band 2742 * data may creep in... ick. 2743 */ 2744 if (th->th_urp <= (u_int16_t)tlen && 2745 (so->so_options & SO_OOBINLINE) == 0) 2746 tcp_pulloutofband(so, th, m, hdroptlen); 2747 } else { 2748 /* 2749 * If no out of band data is expected, 2750 * pull receive urgent pointer along 2751 * with the receive window. 2752 */ 2753 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) 2754 tp->rcv_up = tp->rcv_nxt; 2755 } 2756 dodata: 2757 2758 /* 2759 * Process the segment text, merging it into the TCP sequencing queue, 2760 * and arranging for acknowledgement of receipt if necessary. 2761 * This process logically involves adjusting tp->rcv_wnd as data 2762 * is presented to the user (this happens in tcp_usrreq.c, 2763 * tcp_rcvd()). If a FIN has already been received on this 2764 * connection then we just ignore the text. 2765 */ 2766 if ((tlen || (tiflags & TH_FIN)) && 2767 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2768 /* 2769 * Handle the common case: 2770 * o Segment is the next to be received, and 2771 * o The queue is empty, and 2772 * o The connection is established 2773 * In this case, we avoid calling tcp_reass. 2774 * 2775 * tcp_setup_ack: set DELACK for segments received in order, 2776 * but ack immediately when segments are out of order (so that 2777 * fast retransmit can work). 2778 */ 2779 TCP_REASS_LOCK(tp); 2780 if (th->th_seq == tp->rcv_nxt && 2781 TAILQ_FIRST(&tp->segq) == NULL && 2782 tp->t_state == TCPS_ESTABLISHED) { 2783 tcp_setup_ack(tp, th); 2784 tp->rcv_nxt += tlen; 2785 tiflags = th->th_flags & TH_FIN; 2786 tcps = TCP_STAT_GETREF(); 2787 tcps[TCP_STAT_RCVPACK]++; 2788 tcps[TCP_STAT_RCVBYTE] += tlen; 2789 TCP_STAT_PUTREF(); 2790 nd6_hint(tp); 2791 if (so->so_state & SS_CANTRCVMORE) { 2792 m_freem(m); 2793 } else { 2794 m_adj(m, hdroptlen); 2795 sbappendstream(&(so)->so_rcv, m); 2796 } 2797 TCP_REASS_UNLOCK(tp); 2798 sorwakeup(so); 2799 } else { 2800 m_adj(m, hdroptlen); 2801 tiflags = tcp_reass(tp, th, m, tlen); 2802 tp->t_flags |= TF_ACKNOW; 2803 } 2804 2805 /* 2806 * Note the amount of data that peer has sent into 2807 * our window, in order to estimate the sender's 2808 * buffer size. 2809 */ 2810 len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); 2811 } else { 2812 m_freem(m); 2813 m = NULL; 2814 tiflags &= ~TH_FIN; 2815 } 2816 2817 /* 2818 * If FIN is received ACK the FIN and let the user know 2819 * that the connection is closing. Ignore a FIN received before 2820 * the connection is fully established. 2821 */ 2822 if ((tiflags & TH_FIN) && TCPS_HAVEESTABLISHED(tp->t_state)) { 2823 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2824 socantrcvmore(so); 2825 tp->t_flags |= TF_ACKNOW; 2826 tp->rcv_nxt++; 2827 } 2828 switch (tp->t_state) { 2829 2830 /* 2831 * In ESTABLISHED STATE enter the CLOSE_WAIT state. 2832 */ 2833 case TCPS_ESTABLISHED: 2834 tp->t_state = TCPS_CLOSE_WAIT; 2835 break; 2836 2837 /* 2838 * If still in FIN_WAIT_1 STATE FIN has not been acked so 2839 * enter the CLOSING state. 2840 */ 2841 case TCPS_FIN_WAIT_1: 2842 tp->t_state = TCPS_CLOSING; 2843 break; 2844 2845 /* 2846 * In FIN_WAIT_2 state enter the TIME_WAIT state, 2847 * starting the time-wait timer, turning off the other 2848 * standard timers. 2849 */ 2850 case TCPS_FIN_WAIT_2: 2851 tp->t_state = TCPS_TIME_WAIT; 2852 tcp_canceltimers(tp); 2853 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * tp->t_msl); 2854 soisdisconnected(so); 2855 break; 2856 2857 /* 2858 * In TIME_WAIT state restart the 2 MSL time_wait timer. 2859 */ 2860 case TCPS_TIME_WAIT: 2861 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * tp->t_msl); 2862 break; 2863 } 2864 } 2865 #ifdef TCP_DEBUG 2866 if (so->so_options & SO_DEBUG) 2867 tcp_trace(TA_INPUT, ostate, tp, tcp_saveti, 0); 2868 #endif 2869 2870 /* 2871 * Return any desired output. 2872 */ 2873 if (needoutput || (tp->t_flags & TF_ACKNOW)) { 2874 KERNEL_LOCK(1, NULL); 2875 (void)tcp_output(tp); 2876 KERNEL_UNLOCK_ONE(NULL); 2877 } 2878 if (tcp_saveti) 2879 m_freem(tcp_saveti); 2880 2881 if (tp->t_state == TCPS_TIME_WAIT 2882 && (so->so_state & SS_NOFDREF) 2883 && (tp->t_inpcb || af != AF_INET) 2884 && (tp->t_in6pcb || af != AF_INET6) 2885 && ((af == AF_INET ? tcp4_vtw_enable : tcp6_vtw_enable) & 1) != 0 2886 && TAILQ_EMPTY(&tp->segq) 2887 && vtw_add(af, tp)) { 2888 ; 2889 } 2890 return; 2891 2892 badsyn: 2893 /* 2894 * Received a bad SYN. Increment counters and dropwithreset. 2895 */ 2896 TCP_STATINC(TCP_STAT_BADSYN); 2897 tp = NULL; 2898 goto dropwithreset; 2899 2900 dropafterack: 2901 /* 2902 * Generate an ACK dropping incoming segment if it occupies 2903 * sequence space, where the ACK reflects our state. 2904 */ 2905 if (tiflags & TH_RST) 2906 goto drop; 2907 goto dropafterack2; 2908 2909 dropafterack_ratelim: 2910 /* 2911 * We may want to rate-limit ACKs against SYN/RST attack. 2912 */ 2913 if (ppsratecheck(&tcp_ackdrop_ppslim_last, &tcp_ackdrop_ppslim_count, 2914 tcp_ackdrop_ppslim) == 0) { 2915 /* XXX stat */ 2916 goto drop; 2917 } 2918 2919 dropafterack2: 2920 m_freem(m); 2921 tp->t_flags |= TF_ACKNOW; 2922 KERNEL_LOCK(1, NULL); 2923 (void)tcp_output(tp); 2924 KERNEL_UNLOCK_ONE(NULL); 2925 if (tcp_saveti) 2926 m_freem(tcp_saveti); 2927 return; 2928 2929 dropwithreset_ratelim: 2930 /* 2931 * We may want to rate-limit RSTs in certain situations, 2932 * particularly if we are sending an RST in response to 2933 * an attempt to connect to or otherwise communicate with 2934 * a port for which we have no socket. 2935 */ 2936 if (ppsratecheck(&tcp_rst_ppslim_last, &tcp_rst_ppslim_count, 2937 tcp_rst_ppslim) == 0) { 2938 /* XXX stat */ 2939 goto drop; 2940 } 2941 2942 dropwithreset: 2943 /* 2944 * Generate a RST, dropping incoming segment. 2945 * Make ACK acceptable to originator of segment. 2946 */ 2947 if (tiflags & TH_RST) 2948 goto drop; 2949 if (tiflags & TH_ACK) { 2950 (void)tcp_respond(tp, m, m, th, (tcp_seq)0, th->th_ack, TH_RST); 2951 } else { 2952 if (tiflags & TH_SYN) 2953 tlen++; 2954 (void)tcp_respond(tp, m, m, th, th->th_seq + tlen, (tcp_seq)0, 2955 TH_RST|TH_ACK); 2956 } 2957 if (tcp_saveti) 2958 m_freem(tcp_saveti); 2959 return; 2960 2961 badcsum: 2962 drop: 2963 /* 2964 * Drop space held by incoming segment and return. 2965 */ 2966 if (tp) { 2967 if (tp->t_inpcb) 2968 so = tp->t_inpcb->inp_socket; 2969 #ifdef INET6 2970 else if (tp->t_in6pcb) 2971 so = tp->t_in6pcb->in6p_socket; 2972 #endif 2973 else 2974 so = NULL; 2975 #ifdef TCP_DEBUG 2976 if (so && (so->so_options & SO_DEBUG) != 0) 2977 tcp_trace(TA_DROP, ostate, tp, tcp_saveti, 0); 2978 #endif 2979 } 2980 if (tcp_saveti) 2981 m_freem(tcp_saveti); 2982 m_freem(m); 2983 return; 2984 } 2985 2986 #ifdef TCP_SIGNATURE 2987 int 2988 tcp_signature_apply(void *fstate, void *data, u_int len) 2989 { 2990 2991 MD5Update(fstate, (u_char *)data, len); 2992 return (0); 2993 } 2994 2995 struct secasvar * 2996 tcp_signature_getsav(struct mbuf *m) 2997 { 2998 struct ip *ip; 2999 struct ip6_hdr *ip6; 3000 3001 ip = mtod(m, struct ip *); 3002 switch (ip->ip_v) { 3003 case 4: 3004 ip = mtod(m, struct ip *); 3005 ip6 = NULL; 3006 break; 3007 case 6: 3008 ip = NULL; 3009 ip6 = mtod(m, struct ip6_hdr *); 3010 break; 3011 default: 3012 return (NULL); 3013 } 3014 3015 #ifdef IPSEC 3016 union sockaddr_union dst; 3017 3018 /* Extract the destination from the IP header in the mbuf. */ 3019 memset(&dst, 0, sizeof(union sockaddr_union)); 3020 if (ip != NULL) { 3021 dst.sa.sa_len = sizeof(struct sockaddr_in); 3022 dst.sa.sa_family = AF_INET; 3023 dst.sin.sin_addr = ip->ip_dst; 3024 } else { 3025 dst.sa.sa_len = sizeof(struct sockaddr_in6); 3026 dst.sa.sa_family = AF_INET6; 3027 dst.sin6.sin6_addr = ip6->ip6_dst; 3028 } 3029 3030 /* 3031 * Look up an SADB entry which matches the address of the peer. 3032 */ 3033 return KEY_LOOKUP_SA(&dst, IPPROTO_TCP, htonl(TCP_SIG_SPI), 0, 0); 3034 #else 3035 return NULL; 3036 #endif 3037 } 3038 3039 int 3040 tcp_signature(struct mbuf *m, struct tcphdr *th, int thoff, 3041 struct secasvar *sav, char *sig) 3042 { 3043 MD5_CTX ctx; 3044 struct ip *ip; 3045 struct ipovly *ipovly; 3046 #ifdef INET6 3047 struct ip6_hdr *ip6; 3048 struct ip6_hdr_pseudo ip6pseudo; 3049 #endif 3050 struct ippseudo ippseudo; 3051 struct tcphdr th0; 3052 int l, tcphdrlen; 3053 3054 if (sav == NULL) 3055 return (-1); 3056 3057 tcphdrlen = th->th_off * 4; 3058 3059 switch (mtod(m, struct ip *)->ip_v) { 3060 case 4: 3061 MD5Init(&ctx); 3062 ip = mtod(m, struct ip *); 3063 memset(&ippseudo, 0, sizeof(ippseudo)); 3064 ipovly = (struct ipovly *)ip; 3065 ippseudo.ippseudo_src = ipovly->ih_src; 3066 ippseudo.ippseudo_dst = ipovly->ih_dst; 3067 ippseudo.ippseudo_pad = 0; 3068 ippseudo.ippseudo_p = IPPROTO_TCP; 3069 ippseudo.ippseudo_len = htons(m->m_pkthdr.len - thoff); 3070 MD5Update(&ctx, (char *)&ippseudo, sizeof(ippseudo)); 3071 break; 3072 #if INET6 3073 case 6: 3074 MD5Init(&ctx); 3075 ip6 = mtod(m, struct ip6_hdr *); 3076 memset(&ip6pseudo, 0, sizeof(ip6pseudo)); 3077 ip6pseudo.ip6ph_src = ip6->ip6_src; 3078 in6_clearscope(&ip6pseudo.ip6ph_src); 3079 ip6pseudo.ip6ph_dst = ip6->ip6_dst; 3080 in6_clearscope(&ip6pseudo.ip6ph_dst); 3081 ip6pseudo.ip6ph_len = htons(m->m_pkthdr.len - thoff); 3082 ip6pseudo.ip6ph_nxt = IPPROTO_TCP; 3083 MD5Update(&ctx, (char *)&ip6pseudo, sizeof(ip6pseudo)); 3084 break; 3085 #endif 3086 default: 3087 return (-1); 3088 } 3089 3090 th0 = *th; 3091 th0.th_sum = 0; 3092 MD5Update(&ctx, (char *)&th0, sizeof(th0)); 3093 3094 l = m->m_pkthdr.len - thoff - tcphdrlen; 3095 if (l > 0) 3096 m_apply(m, thoff + tcphdrlen, 3097 m->m_pkthdr.len - thoff - tcphdrlen, 3098 tcp_signature_apply, &ctx); 3099 3100 MD5Update(&ctx, _KEYBUF(sav->key_auth), _KEYLEN(sav->key_auth)); 3101 MD5Final(sig, &ctx); 3102 3103 return (0); 3104 } 3105 #endif 3106 3107 /* 3108 * Parse and process tcp options. 3109 * 3110 * Returns -1 if this segment should be dropped. (eg. wrong signature) 3111 * Otherwise returns 0. 3112 */ 3113 static int 3114 tcp_dooptions(struct tcpcb *tp, const u_char *cp, int cnt, struct tcphdr *th, 3115 struct mbuf *m, int toff, struct tcp_opt_info *oi) 3116 { 3117 u_int16_t mss; 3118 int opt, optlen = 0; 3119 #ifdef TCP_SIGNATURE 3120 void *sigp = NULL; 3121 char sigbuf[TCP_SIGLEN]; 3122 struct secasvar *sav = NULL; 3123 #endif 3124 3125 for (; cp && cnt > 0; cnt -= optlen, cp += optlen) { 3126 opt = cp[0]; 3127 if (opt == TCPOPT_EOL) 3128 break; 3129 if (opt == TCPOPT_NOP) 3130 optlen = 1; 3131 else { 3132 if (cnt < 2) 3133 break; 3134 optlen = cp[1]; 3135 if (optlen < 2 || optlen > cnt) 3136 break; 3137 } 3138 switch (opt) { 3139 3140 default: 3141 continue; 3142 3143 case TCPOPT_MAXSEG: 3144 if (optlen != TCPOLEN_MAXSEG) 3145 continue; 3146 if (!(th->th_flags & TH_SYN)) 3147 continue; 3148 if (TCPS_HAVERCVDSYN(tp->t_state)) 3149 continue; 3150 memcpy(&mss, cp + 2, sizeof(mss)); 3151 oi->maxseg = ntohs(mss); 3152 break; 3153 3154 case TCPOPT_WINDOW: 3155 if (optlen != TCPOLEN_WINDOW) 3156 continue; 3157 if (!(th->th_flags & TH_SYN)) 3158 continue; 3159 if (TCPS_HAVERCVDSYN(tp->t_state)) 3160 continue; 3161 tp->t_flags |= TF_RCVD_SCALE; 3162 tp->requested_s_scale = cp[2]; 3163 if (tp->requested_s_scale > TCP_MAX_WINSHIFT) { 3164 char buf[INET6_ADDRSTRLEN]; 3165 struct ip *ip = mtod(m, struct ip *); 3166 #ifdef INET6 3167 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *); 3168 #endif 3169 3170 switch (ip->ip_v) { 3171 case 4: 3172 in_print(buf, sizeof(buf), 3173 &ip->ip_src); 3174 break; 3175 #ifdef INET6 3176 case 6: 3177 in6_print(buf, sizeof(buf), 3178 &ip6->ip6_src); 3179 break; 3180 #endif 3181 default: 3182 strlcpy(buf, "(unknown)", sizeof(buf)); 3183 break; 3184 } 3185 3186 log(LOG_ERR, "TCP: invalid wscale %d from %s, " 3187 "assuming %d\n", 3188 tp->requested_s_scale, buf, 3189 TCP_MAX_WINSHIFT); 3190 tp->requested_s_scale = TCP_MAX_WINSHIFT; 3191 } 3192 break; 3193 3194 case TCPOPT_TIMESTAMP: 3195 if (optlen != TCPOLEN_TIMESTAMP) 3196 continue; 3197 oi->ts_present = 1; 3198 memcpy(&oi->ts_val, cp + 2, sizeof(oi->ts_val)); 3199 NTOHL(oi->ts_val); 3200 memcpy(&oi->ts_ecr, cp + 6, sizeof(oi->ts_ecr)); 3201 NTOHL(oi->ts_ecr); 3202 3203 if (!(th->th_flags & TH_SYN)) 3204 continue; 3205 if (TCPS_HAVERCVDSYN(tp->t_state)) 3206 continue; 3207 /* 3208 * A timestamp received in a SYN makes 3209 * it ok to send timestamp requests and replies. 3210 */ 3211 tp->t_flags |= TF_RCVD_TSTMP; 3212 tp->ts_recent = oi->ts_val; 3213 tp->ts_recent_age = tcp_now; 3214 break; 3215 3216 case TCPOPT_SACK_PERMITTED: 3217 if (optlen != TCPOLEN_SACK_PERMITTED) 3218 continue; 3219 if (!(th->th_flags & TH_SYN)) 3220 continue; 3221 if (TCPS_HAVERCVDSYN(tp->t_state)) 3222 continue; 3223 if (tcp_do_sack) { 3224 tp->t_flags |= TF_SACK_PERMIT; 3225 tp->t_flags |= TF_WILL_SACK; 3226 } 3227 break; 3228 3229 case TCPOPT_SACK: 3230 tcp_sack_option(tp, th, cp, optlen); 3231 break; 3232 #ifdef TCP_SIGNATURE 3233 case TCPOPT_SIGNATURE: 3234 if (optlen != TCPOLEN_SIGNATURE) 3235 continue; 3236 if (sigp && 3237 !consttime_memequal(sigp, cp + 2, TCP_SIGLEN)) 3238 return (-1); 3239 3240 sigp = sigbuf; 3241 memcpy(sigbuf, cp + 2, TCP_SIGLEN); 3242 tp->t_flags |= TF_SIGNATURE; 3243 break; 3244 #endif 3245 } 3246 } 3247 3248 #ifndef TCP_SIGNATURE 3249 return 0; 3250 #else 3251 if (tp->t_flags & TF_SIGNATURE) { 3252 sav = tcp_signature_getsav(m); 3253 if (sav == NULL && tp->t_state == TCPS_LISTEN) 3254 return (-1); 3255 } 3256 3257 if ((sigp ? TF_SIGNATURE : 0) ^ (tp->t_flags & TF_SIGNATURE)) 3258 goto out; 3259 3260 if (sigp) { 3261 char sig[TCP_SIGLEN]; 3262 3263 tcp_fields_to_net(th); 3264 if (tcp_signature(m, th, toff, sav, sig) < 0) { 3265 tcp_fields_to_host(th); 3266 goto out; 3267 } 3268 tcp_fields_to_host(th); 3269 3270 if (!consttime_memequal(sig, sigp, TCP_SIGLEN)) { 3271 TCP_STATINC(TCP_STAT_BADSIG); 3272 goto out; 3273 } else 3274 TCP_STATINC(TCP_STAT_GOODSIG); 3275 3276 key_sa_recordxfer(sav, m); 3277 KEY_SA_UNREF(&sav); 3278 } 3279 return 0; 3280 out: 3281 if (sav != NULL) 3282 KEY_SA_UNREF(&sav); 3283 return -1; 3284 #endif 3285 } 3286 3287 /* 3288 * Pull out of band byte out of a segment so 3289 * it doesn't appear in the user's data queue. 3290 * It is still reflected in the segment length for 3291 * sequencing purposes. 3292 */ 3293 void 3294 tcp_pulloutofband(struct socket *so, struct tcphdr *th, 3295 struct mbuf *m, int off) 3296 { 3297 int cnt = off + th->th_urp - 1; 3298 3299 while (cnt >= 0) { 3300 if (m->m_len > cnt) { 3301 char *cp = mtod(m, char *) + cnt; 3302 struct tcpcb *tp = sototcpcb(so); 3303 3304 tp->t_iobc = *cp; 3305 tp->t_oobflags |= TCPOOB_HAVEDATA; 3306 memmove(cp, cp + 1, (unsigned)(m->m_len - cnt - 1)); 3307 m->m_len--; 3308 return; 3309 } 3310 cnt -= m->m_len; 3311 m = m->m_next; 3312 if (m == NULL) 3313 break; 3314 } 3315 panic("tcp_pulloutofband"); 3316 } 3317 3318 /* 3319 * Collect new round-trip time estimate 3320 * and update averages and current timeout. 3321 * 3322 * rtt is in units of slow ticks (typically 500 ms) -- essentially the 3323 * difference of two timestamps. 3324 */ 3325 void 3326 tcp_xmit_timer(struct tcpcb *tp, uint32_t rtt) 3327 { 3328 int32_t delta; 3329 3330 TCP_STATINC(TCP_STAT_RTTUPDATED); 3331 if (tp->t_srtt != 0) { 3332 /* 3333 * Compute the amount to add to srtt for smoothing, 3334 * *alpha, or 2^(-TCP_RTT_SHIFT). Because 3335 * srtt is stored in 1/32 slow ticks, we conceptually 3336 * shift left 5 bits, subtract srtt to get the 3337 * diference, and then shift right by TCP_RTT_SHIFT 3338 * (3) to obtain 1/8 of the difference. 3339 */ 3340 delta = (rtt << 2) - (tp->t_srtt >> TCP_RTT_SHIFT); 3341 /* 3342 * This can never happen, because delta's lowest 3343 * possible value is 1/8 of t_srtt. But if it does, 3344 * set srtt to some reasonable value, here chosen 3345 * as 1/8 tick. 3346 */ 3347 if ((tp->t_srtt += delta) <= 0) 3348 tp->t_srtt = 1 << 2; 3349 /* 3350 * RFC2988 requires that rttvar be updated first. 3351 * This code is compliant because "delta" is the old 3352 * srtt minus the new observation (scaled). 3353 * 3354 * RFC2988 says: 3355 * rttvar = (1-beta) * rttvar + beta * |srtt-observed| 3356 * 3357 * delta is in units of 1/32 ticks, and has then been 3358 * divided by 8. This is equivalent to being in 1/16s 3359 * units and divided by 4. Subtract from it 1/4 of 3360 * the existing rttvar to form the (signed) amount to 3361 * adjust. 3362 */ 3363 if (delta < 0) 3364 delta = -delta; 3365 delta -= (tp->t_rttvar >> TCP_RTTVAR_SHIFT); 3366 /* 3367 * As with srtt, this should never happen. There is 3368 * no support in RFC2988 for this operation. But 1/4s 3369 * as rttvar when faced with something arguably wrong 3370 * is ok. 3371 */ 3372 if ((tp->t_rttvar += delta) <= 0) 3373 tp->t_rttvar = 1 << 2; 3374 3375 /* 3376 * If srtt exceeds .01 second, ensure we use the 'remote' MSL 3377 * Problem is: it doesn't work. Disabled by defaulting 3378 * tcp_rttlocal to 0; see corresponding code in 3379 * tcp_subr that selects local vs remote in a different way. 3380 * 3381 * The static branch prediction hint here should be removed 3382 * when the rtt estimator is fixed and the rtt_enable code 3383 * is turned back on. 3384 */ 3385 if (__predict_false(tcp_rttlocal) && tcp_msl_enable 3386 && tp->t_srtt > tcp_msl_remote_threshold 3387 && tp->t_msl < tcp_msl_remote) { 3388 tp->t_msl = tcp_msl_remote; 3389 } 3390 } else { 3391 /* 3392 * This is the first measurement. Per RFC2988, 2.2, 3393 * set rtt=R and srtt=R/2. 3394 * For srtt, storage representation is 1/32 ticks, 3395 * so shift left by 5. 3396 * For rttvar, storage representation is 1/16 ticks, 3397 * So shift left by 4, but then right by 1 to halve. 3398 */ 3399 tp->t_srtt = rtt << (TCP_RTT_SHIFT + 2); 3400 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT + 2 - 1); 3401 } 3402 tp->t_rtttime = 0; 3403 tp->t_rxtshift = 0; 3404 3405 /* 3406 * the retransmit should happen at rtt + 4 * rttvar. 3407 * Because of the way we do the smoothing, srtt and rttvar 3408 * will each average +1/2 tick of bias. When we compute 3409 * the retransmit timer, we want 1/2 tick of rounding and 3410 * 1 extra tick because of +-1/2 tick uncertainty in the 3411 * firing of the timer. The bias will give us exactly the 3412 * 1.5 tick we need. But, because the bias is 3413 * statistical, we have to test that we don't drop below 3414 * the minimum feasible timer (which is 2 ticks). 3415 */ 3416 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), 3417 max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX); 3418 3419 /* 3420 * We received an ack for a packet that wasn't retransmitted; 3421 * it is probably safe to discard any error indications we've 3422 * received recently. This isn't quite right, but close enough 3423 * for now (a route might have failed after we sent a segment, 3424 * and the return path might not be symmetrical). 3425 */ 3426 tp->t_softerror = 0; 3427 } 3428 3429 3430 /* 3431 * TCP compressed state engine. Currently used to hold compressed 3432 * state for SYN_RECEIVED. 3433 */ 3434 3435 u_long syn_cache_count; 3436 u_int32_t syn_hash1, syn_hash2; 3437 3438 #define SYN_HASH(sa, sp, dp) \ 3439 ((((sa)->s_addr^syn_hash1)*(((((u_int32_t)(dp))<<16) + \ 3440 ((u_int32_t)(sp)))^syn_hash2))) 3441 #ifndef INET6 3442 #define SYN_HASHALL(hash, src, dst) \ 3443 do { \ 3444 hash = SYN_HASH(&((const struct sockaddr_in *)(src))->sin_addr, \ 3445 ((const struct sockaddr_in *)(src))->sin_port, \ 3446 ((const struct sockaddr_in *)(dst))->sin_port); \ 3447 } while (/*CONSTCOND*/ 0) 3448 #else 3449 #define SYN_HASH6(sa, sp, dp) \ 3450 ((((sa)->s6_addr32[0] ^ (sa)->s6_addr32[3] ^ syn_hash1) * \ 3451 (((((u_int32_t)(dp))<<16) + ((u_int32_t)(sp)))^syn_hash2)) \ 3452 & 0x7fffffff) 3453 3454 #define SYN_HASHALL(hash, src, dst) \ 3455 do { \ 3456 switch ((src)->sa_family) { \ 3457 case AF_INET: \ 3458 hash = SYN_HASH(&((const struct sockaddr_in *)(src))->sin_addr, \ 3459 ((const struct sockaddr_in *)(src))->sin_port, \ 3460 ((const struct sockaddr_in *)(dst))->sin_port); \ 3461 break; \ 3462 case AF_INET6: \ 3463 hash = SYN_HASH6(&((const struct sockaddr_in6 *)(src))->sin6_addr, \ 3464 ((const struct sockaddr_in6 *)(src))->sin6_port, \ 3465 ((const struct sockaddr_in6 *)(dst))->sin6_port); \ 3466 break; \ 3467 default: \ 3468 hash = 0; \ 3469 } \ 3470 } while (/*CONSTCOND*/0) 3471 #endif /* INET6 */ 3472 3473 static struct pool syn_cache_pool; 3474 3475 /* 3476 * We don't estimate RTT with SYNs, so each packet starts with the default 3477 * RTT and each timer step has a fixed timeout value. 3478 */ 3479 static inline void 3480 syn_cache_timer_arm(struct syn_cache *sc) 3481 { 3482 3483 TCPT_RANGESET(sc->sc_rxtcur, 3484 TCPTV_SRTTDFLT * tcp_backoff[sc->sc_rxtshift], TCPTV_MIN, 3485 TCPTV_REXMTMAX); 3486 callout_reset(&sc->sc_timer, 3487 sc->sc_rxtcur * (hz / PR_SLOWHZ), syn_cache_timer, sc); 3488 } 3489 3490 #define SYN_CACHE_TIMESTAMP(sc) (tcp_now - (sc)->sc_timebase) 3491 3492 static inline void 3493 syn_cache_rm(struct syn_cache *sc) 3494 { 3495 TAILQ_REMOVE(&tcp_syn_cache[sc->sc_bucketidx].sch_bucket, 3496 sc, sc_bucketq); 3497 sc->sc_tp = NULL; 3498 LIST_REMOVE(sc, sc_tpq); 3499 tcp_syn_cache[sc->sc_bucketidx].sch_length--; 3500 callout_stop(&sc->sc_timer); 3501 syn_cache_count--; 3502 } 3503 3504 static inline void 3505 syn_cache_put(struct syn_cache *sc) 3506 { 3507 if (sc->sc_ipopts) 3508 (void) m_free(sc->sc_ipopts); 3509 rtcache_free(&sc->sc_route); 3510 sc->sc_flags |= SCF_DEAD; 3511 if (!callout_invoking(&sc->sc_timer)) 3512 callout_schedule(&(sc)->sc_timer, 1); 3513 } 3514 3515 void 3516 syn_cache_init(void) 3517 { 3518 int i; 3519 3520 pool_init(&syn_cache_pool, sizeof(struct syn_cache), 0, 0, 0, 3521 "synpl", NULL, IPL_SOFTNET); 3522 3523 /* Initialize the hash buckets. */ 3524 for (i = 0; i < tcp_syn_cache_size; i++) 3525 TAILQ_INIT(&tcp_syn_cache[i].sch_bucket); 3526 } 3527 3528 void 3529 syn_cache_insert(struct syn_cache *sc, struct tcpcb *tp) 3530 { 3531 struct syn_cache_head *scp; 3532 struct syn_cache *sc2; 3533 int s; 3534 3535 /* 3536 * If there are no entries in the hash table, reinitialize 3537 * the hash secrets. 3538 */ 3539 if (syn_cache_count == 0) { 3540 syn_hash1 = cprng_fast32(); 3541 syn_hash2 = cprng_fast32(); 3542 } 3543 3544 SYN_HASHALL(sc->sc_hash, &sc->sc_src.sa, &sc->sc_dst.sa); 3545 sc->sc_bucketidx = sc->sc_hash % tcp_syn_cache_size; 3546 scp = &tcp_syn_cache[sc->sc_bucketidx]; 3547 3548 /* 3549 * Make sure that we don't overflow the per-bucket 3550 * limit or the total cache size limit. 3551 */ 3552 s = splsoftnet(); 3553 if (scp->sch_length >= tcp_syn_bucket_limit) { 3554 TCP_STATINC(TCP_STAT_SC_BUCKETOVERFLOW); 3555 /* 3556 * The bucket is full. Toss the oldest element in the 3557 * bucket. This will be the first entry in the bucket. 3558 */ 3559 sc2 = TAILQ_FIRST(&scp->sch_bucket); 3560 #ifdef DIAGNOSTIC 3561 /* 3562 * This should never happen; we should always find an 3563 * entry in our bucket. 3564 */ 3565 if (sc2 == NULL) 3566 panic("syn_cache_insert: bucketoverflow: impossible"); 3567 #endif 3568 syn_cache_rm(sc2); 3569 syn_cache_put(sc2); /* calls pool_put but see spl above */ 3570 } else if (syn_cache_count >= tcp_syn_cache_limit) { 3571 struct syn_cache_head *scp2, *sce; 3572 3573 TCP_STATINC(TCP_STAT_SC_OVERFLOWED); 3574 /* 3575 * The cache is full. Toss the oldest entry in the 3576 * first non-empty bucket we can find. 3577 * 3578 * XXX We would really like to toss the oldest 3579 * entry in the cache, but we hope that this 3580 * condition doesn't happen very often. 3581 */ 3582 scp2 = scp; 3583 if (TAILQ_EMPTY(&scp2->sch_bucket)) { 3584 sce = &tcp_syn_cache[tcp_syn_cache_size]; 3585 for (++scp2; scp2 != scp; scp2++) { 3586 if (scp2 >= sce) 3587 scp2 = &tcp_syn_cache[0]; 3588 if (! TAILQ_EMPTY(&scp2->sch_bucket)) 3589 break; 3590 } 3591 #ifdef DIAGNOSTIC 3592 /* 3593 * This should never happen; we should always find a 3594 * non-empty bucket. 3595 */ 3596 if (scp2 == scp) 3597 panic("syn_cache_insert: cacheoverflow: " 3598 "impossible"); 3599 #endif 3600 } 3601 sc2 = TAILQ_FIRST(&scp2->sch_bucket); 3602 syn_cache_rm(sc2); 3603 syn_cache_put(sc2); /* calls pool_put but see spl above */ 3604 } 3605 3606 /* 3607 * Initialize the entry's timer. 3608 */ 3609 sc->sc_rxttot = 0; 3610 sc->sc_rxtshift = 0; 3611 syn_cache_timer_arm(sc); 3612 3613 /* Link it from tcpcb entry */ 3614 LIST_INSERT_HEAD(&tp->t_sc, sc, sc_tpq); 3615 3616 /* Put it into the bucket. */ 3617 TAILQ_INSERT_TAIL(&scp->sch_bucket, sc, sc_bucketq); 3618 scp->sch_length++; 3619 syn_cache_count++; 3620 3621 TCP_STATINC(TCP_STAT_SC_ADDED); 3622 splx(s); 3623 } 3624 3625 /* 3626 * Walk the timer queues, looking for SYN,ACKs that need to be retransmitted. 3627 * If we have retransmitted an entry the maximum number of times, expire 3628 * that entry. 3629 */ 3630 static void 3631 syn_cache_timer(void *arg) 3632 { 3633 struct syn_cache *sc = arg; 3634 3635 mutex_enter(softnet_lock); 3636 KERNEL_LOCK(1, NULL); 3637 3638 callout_ack(&sc->sc_timer); 3639 3640 if (__predict_false(sc->sc_flags & SCF_DEAD)) { 3641 TCP_STATINC(TCP_STAT_SC_DELAYED_FREE); 3642 goto free; 3643 } 3644 3645 if (__predict_false(sc->sc_rxtshift == TCP_MAXRXTSHIFT)) { 3646 /* Drop it -- too many retransmissions. */ 3647 goto dropit; 3648 } 3649 3650 /* 3651 * Compute the total amount of time this entry has 3652 * been on a queue. If this entry has been on longer 3653 * than the keep alive timer would allow, expire it. 3654 */ 3655 sc->sc_rxttot += sc->sc_rxtcur; 3656 if (sc->sc_rxttot >= tcp_keepinit) 3657 goto dropit; 3658 3659 TCP_STATINC(TCP_STAT_SC_RETRANSMITTED); 3660 (void)syn_cache_respond(sc); 3661 3662 /* Advance the timer back-off. */ 3663 sc->sc_rxtshift++; 3664 syn_cache_timer_arm(sc); 3665 3666 goto out; 3667 3668 dropit: 3669 TCP_STATINC(TCP_STAT_SC_TIMED_OUT); 3670 syn_cache_rm(sc); 3671 if (sc->sc_ipopts) 3672 (void) m_free(sc->sc_ipopts); 3673 rtcache_free(&sc->sc_route); 3674 3675 free: 3676 callout_destroy(&sc->sc_timer); 3677 pool_put(&syn_cache_pool, sc); 3678 3679 out: 3680 KERNEL_UNLOCK_ONE(NULL); 3681 mutex_exit(softnet_lock); 3682 } 3683 3684 /* 3685 * Remove syn cache created by the specified tcb entry, 3686 * because this does not make sense to keep them 3687 * (if there's no tcb entry, syn cache entry will never be used) 3688 */ 3689 void 3690 syn_cache_cleanup(struct tcpcb *tp) 3691 { 3692 struct syn_cache *sc, *nsc; 3693 int s; 3694 3695 s = splsoftnet(); 3696 3697 for (sc = LIST_FIRST(&tp->t_sc); sc != NULL; sc = nsc) { 3698 nsc = LIST_NEXT(sc, sc_tpq); 3699 3700 #ifdef DIAGNOSTIC 3701 if (sc->sc_tp != tp) 3702 panic("invalid sc_tp in syn_cache_cleanup"); 3703 #endif 3704 syn_cache_rm(sc); 3705 syn_cache_put(sc); /* calls pool_put but see spl above */ 3706 } 3707 /* just for safety */ 3708 LIST_INIT(&tp->t_sc); 3709 3710 splx(s); 3711 } 3712 3713 /* 3714 * Find an entry in the syn cache. 3715 */ 3716 struct syn_cache * 3717 syn_cache_lookup(const struct sockaddr *src, const struct sockaddr *dst, 3718 struct syn_cache_head **headp) 3719 { 3720 struct syn_cache *sc; 3721 struct syn_cache_head *scp; 3722 u_int32_t hash; 3723 int s; 3724 3725 SYN_HASHALL(hash, src, dst); 3726 3727 scp = &tcp_syn_cache[hash % tcp_syn_cache_size]; 3728 *headp = scp; 3729 s = splsoftnet(); 3730 for (sc = TAILQ_FIRST(&scp->sch_bucket); sc != NULL; 3731 sc = TAILQ_NEXT(sc, sc_bucketq)) { 3732 if (sc->sc_hash != hash) 3733 continue; 3734 if (!memcmp(&sc->sc_src, src, src->sa_len) && 3735 !memcmp(&sc->sc_dst, dst, dst->sa_len)) { 3736 splx(s); 3737 return (sc); 3738 } 3739 } 3740 splx(s); 3741 return (NULL); 3742 } 3743 3744 /* 3745 * This function gets called when we receive an ACK for a socket in the 3746 * LISTEN state. We look up the connection in the syn cache, and if it's 3747 * there, we pull it out of the cache and turn it into a full-blown 3748 * connection in the SYN-RECEIVED state. 3749 * 3750 * The return values may not be immediately obvious, and their effects 3751 * can be subtle, so here they are: 3752 * 3753 * NULL SYN was not found in cache; caller should drop the 3754 * packet and send an RST. 3755 * 3756 * -1 We were unable to create the new connection, and are 3757 * aborting it. An ACK,RST is being sent to the peer 3758 * (unless we got screwey sequence numbers; see below), 3759 * because the 3-way handshake has been completed. Caller 3760 * should not free the mbuf, since we may be using it. If 3761 * we are not, we will free it. 3762 * 3763 * Otherwise, the return value is a pointer to the new socket 3764 * associated with the connection. 3765 */ 3766 struct socket * 3767 syn_cache_get(struct sockaddr *src, struct sockaddr *dst, 3768 struct tcphdr *th, struct socket *so, struct mbuf *m) 3769 { 3770 struct syn_cache *sc; 3771 struct syn_cache_head *scp; 3772 struct inpcb *inp = NULL; 3773 #ifdef INET6 3774 struct in6pcb *in6p = NULL; 3775 #endif 3776 struct tcpcb *tp; 3777 int s; 3778 struct socket *oso; 3779 3780 s = splsoftnet(); 3781 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 3782 splx(s); 3783 return NULL; 3784 } 3785 3786 /* 3787 * Verify the sequence and ack numbers. Try getting the correct 3788 * response again. 3789 */ 3790 if ((th->th_ack != sc->sc_iss + 1) || 3791 SEQ_LEQ(th->th_seq, sc->sc_irs) || 3792 SEQ_GT(th->th_seq, sc->sc_irs + 1 + sc->sc_win)) { 3793 m_freem(m); 3794 (void)syn_cache_respond(sc); 3795 splx(s); 3796 return ((struct socket *)(-1)); 3797 } 3798 3799 /* Remove this cache entry */ 3800 syn_cache_rm(sc); 3801 splx(s); 3802 3803 /* 3804 * Ok, create the full blown connection, and set things up 3805 * as they would have been set up if we had created the 3806 * connection when the SYN arrived. If we can't create 3807 * the connection, abort it. 3808 */ 3809 /* 3810 * inp still has the OLD in_pcb stuff, set the 3811 * v6-related flags on the new guy, too. This is 3812 * done particularly for the case where an AF_INET6 3813 * socket is bound only to a port, and a v4 connection 3814 * comes in on that port. 3815 * we also copy the flowinfo from the original pcb 3816 * to the new one. 3817 */ 3818 oso = so; 3819 so = sonewconn(so, true); 3820 if (so == NULL) 3821 goto resetandabort; 3822 3823 switch (so->so_proto->pr_domain->dom_family) { 3824 case AF_INET: 3825 inp = sotoinpcb(so); 3826 break; 3827 #ifdef INET6 3828 case AF_INET6: 3829 in6p = sotoin6pcb(so); 3830 break; 3831 #endif 3832 } 3833 3834 switch (src->sa_family) { 3835 case AF_INET: 3836 if (inp) { 3837 inp->inp_laddr = ((struct sockaddr_in *)dst)->sin_addr; 3838 inp->inp_lport = ((struct sockaddr_in *)dst)->sin_port; 3839 inp->inp_options = ip_srcroute(m); 3840 in_pcbstate(inp, INP_BOUND); 3841 if (inp->inp_options == NULL) { 3842 inp->inp_options = sc->sc_ipopts; 3843 sc->sc_ipopts = NULL; 3844 } 3845 } 3846 #ifdef INET6 3847 else if (in6p) { 3848 /* IPv4 packet to AF_INET6 socket */ 3849 memset(&in6p->in6p_laddr, 0, sizeof(in6p->in6p_laddr)); 3850 in6p->in6p_laddr.s6_addr16[5] = htons(0xffff); 3851 bcopy(&((struct sockaddr_in *)dst)->sin_addr, 3852 &in6p->in6p_laddr.s6_addr32[3], 3853 sizeof(((struct sockaddr_in *)dst)->sin_addr)); 3854 in6p->in6p_lport = ((struct sockaddr_in *)dst)->sin_port; 3855 in6totcpcb(in6p)->t_family = AF_INET; 3856 if (sotoin6pcb(oso)->in6p_flags & IN6P_IPV6_V6ONLY) 3857 in6p->in6p_flags |= IN6P_IPV6_V6ONLY; 3858 else 3859 in6p->in6p_flags &= ~IN6P_IPV6_V6ONLY; 3860 in6_pcbstate(in6p, IN6P_BOUND); 3861 } 3862 #endif 3863 break; 3864 #ifdef INET6 3865 case AF_INET6: 3866 if (in6p) { 3867 in6p->in6p_laddr = ((struct sockaddr_in6 *)dst)->sin6_addr; 3868 in6p->in6p_lport = ((struct sockaddr_in6 *)dst)->sin6_port; 3869 in6_pcbstate(in6p, IN6P_BOUND); 3870 } 3871 break; 3872 #endif 3873 } 3874 3875 #ifdef INET6 3876 if (in6p && in6totcpcb(in6p)->t_family == AF_INET6 && sotoinpcb(oso)) { 3877 struct in6pcb *oin6p = sotoin6pcb(oso); 3878 /* inherit socket options from the listening socket */ 3879 in6p->in6p_flags |= (oin6p->in6p_flags & IN6P_CONTROLOPTS); 3880 if (in6p->in6p_flags & IN6P_CONTROLOPTS) { 3881 m_freem(in6p->in6p_options); 3882 in6p->in6p_options = NULL; 3883 } 3884 ip6_savecontrol(in6p, &in6p->in6p_options, 3885 mtod(m, struct ip6_hdr *), m); 3886 } 3887 #endif 3888 3889 /* 3890 * Give the new socket our cached route reference. 3891 */ 3892 if (inp) { 3893 rtcache_copy(&inp->inp_route, &sc->sc_route); 3894 rtcache_free(&sc->sc_route); 3895 } 3896 #ifdef INET6 3897 else { 3898 rtcache_copy(&in6p->in6p_route, &sc->sc_route); 3899 rtcache_free(&sc->sc_route); 3900 } 3901 #endif 3902 3903 if (inp) { 3904 struct sockaddr_in sin; 3905 memcpy(&sin, src, src->sa_len); 3906 if (in_pcbconnect(inp, &sin, &lwp0)) { 3907 goto resetandabort; 3908 } 3909 } 3910 #ifdef INET6 3911 else if (in6p) { 3912 struct sockaddr_in6 sin6; 3913 memcpy(&sin6, src, src->sa_len); 3914 if (src->sa_family == AF_INET) { 3915 /* IPv4 packet to AF_INET6 socket */ 3916 in6_sin_2_v4mapsin6((struct sockaddr_in *)src, &sin6); 3917 } 3918 if (in6_pcbconnect(in6p, &sin6, NULL)) { 3919 goto resetandabort; 3920 } 3921 } 3922 #endif 3923 else { 3924 goto resetandabort; 3925 } 3926 3927 if (inp) 3928 tp = intotcpcb(inp); 3929 #ifdef INET6 3930 else if (in6p) 3931 tp = in6totcpcb(in6p); 3932 #endif 3933 else 3934 tp = NULL; 3935 3936 tp->t_flags = sototcpcb(oso)->t_flags & TF_NODELAY; 3937 if (sc->sc_request_r_scale != 15) { 3938 tp->requested_s_scale = sc->sc_requested_s_scale; 3939 tp->request_r_scale = sc->sc_request_r_scale; 3940 tp->snd_scale = sc->sc_requested_s_scale; 3941 tp->rcv_scale = sc->sc_request_r_scale; 3942 tp->t_flags |= TF_REQ_SCALE|TF_RCVD_SCALE; 3943 } 3944 if (sc->sc_flags & SCF_TIMESTAMP) 3945 tp->t_flags |= TF_REQ_TSTMP|TF_RCVD_TSTMP; 3946 tp->ts_timebase = sc->sc_timebase; 3947 3948 tp->t_template = tcp_template(tp); 3949 if (tp->t_template == 0) { 3950 tp = tcp_drop(tp, ENOBUFS); /* destroys socket */ 3951 so = NULL; 3952 m_freem(m); 3953 goto abort; 3954 } 3955 3956 tp->iss = sc->sc_iss; 3957 tp->irs = sc->sc_irs; 3958 tcp_sendseqinit(tp); 3959 tcp_rcvseqinit(tp); 3960 tp->t_state = TCPS_SYN_RECEIVED; 3961 TCP_TIMER_ARM(tp, TCPT_KEEP, tp->t_keepinit); 3962 TCP_STATINC(TCP_STAT_ACCEPTS); 3963 3964 if ((sc->sc_flags & SCF_SACK_PERMIT) && tcp_do_sack) 3965 tp->t_flags |= TF_WILL_SACK; 3966 3967 if ((sc->sc_flags & SCF_ECN_PERMIT) && tcp_do_ecn) 3968 tp->t_flags |= TF_ECN_PERMIT; 3969 3970 #ifdef TCP_SIGNATURE 3971 if (sc->sc_flags & SCF_SIGNATURE) 3972 tp->t_flags |= TF_SIGNATURE; 3973 #endif 3974 3975 /* Initialize tp->t_ourmss before we deal with the peer's! */ 3976 tp->t_ourmss = sc->sc_ourmaxseg; 3977 tcp_mss_from_peer(tp, sc->sc_peermaxseg); 3978 3979 /* 3980 * Initialize the initial congestion window. If we 3981 * had to retransmit the SYN,ACK, we must initialize cwnd 3982 * to 1 segment (i.e. the Loss Window). 3983 */ 3984 if (sc->sc_rxtshift) 3985 tp->snd_cwnd = tp->t_peermss; 3986 else { 3987 int ss = tcp_init_win; 3988 if (inp != NULL && in_localaddr(inp->inp_faddr)) 3989 ss = tcp_init_win_local; 3990 #ifdef INET6 3991 if (in6p != NULL && in6_localaddr(&in6p->in6p_faddr)) 3992 ss = tcp_init_win_local; 3993 #endif 3994 tp->snd_cwnd = TCP_INITIAL_WINDOW(ss, tp->t_peermss); 3995 } 3996 3997 tcp_rmx_rtt(tp); 3998 tp->snd_wl1 = sc->sc_irs; 3999 tp->rcv_up = sc->sc_irs + 1; 4000 4001 /* 4002 * This is what whould have happened in tcp_output() when 4003 * the SYN,ACK was sent. 4004 */ 4005 tp->snd_up = tp->snd_una; 4006 tp->snd_max = tp->snd_nxt = tp->iss+1; 4007 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 4008 if (sc->sc_win > 0 && SEQ_GT(tp->rcv_nxt + sc->sc_win, tp->rcv_adv)) 4009 tp->rcv_adv = tp->rcv_nxt + sc->sc_win; 4010 tp->last_ack_sent = tp->rcv_nxt; 4011 tp->t_partialacks = -1; 4012 tp->t_dupacks = 0; 4013 4014 TCP_STATINC(TCP_STAT_SC_COMPLETED); 4015 s = splsoftnet(); 4016 syn_cache_put(sc); 4017 splx(s); 4018 return so; 4019 4020 resetandabort: 4021 (void)tcp_respond(NULL, m, m, th, (tcp_seq)0, th->th_ack, TH_RST); 4022 abort: 4023 if (so != NULL) { 4024 (void) soqremque(so, 1); 4025 (void) soabort(so); 4026 mutex_enter(softnet_lock); 4027 } 4028 s = splsoftnet(); 4029 syn_cache_put(sc); 4030 splx(s); 4031 TCP_STATINC(TCP_STAT_SC_ABORTED); 4032 return ((struct socket *)(-1)); 4033 } 4034 4035 /* 4036 * This function is called when we get a RST for a 4037 * non-existent connection, so that we can see if the 4038 * connection is in the syn cache. If it is, zap it. 4039 */ 4040 4041 void 4042 syn_cache_reset(struct sockaddr *src, struct sockaddr *dst, struct tcphdr *th) 4043 { 4044 struct syn_cache *sc; 4045 struct syn_cache_head *scp; 4046 int s = splsoftnet(); 4047 4048 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 4049 splx(s); 4050 return; 4051 } 4052 if (SEQ_LT(th->th_seq, sc->sc_irs) || 4053 SEQ_GT(th->th_seq, sc->sc_irs+1)) { 4054 splx(s); 4055 return; 4056 } 4057 syn_cache_rm(sc); 4058 TCP_STATINC(TCP_STAT_SC_RESET); 4059 syn_cache_put(sc); /* calls pool_put but see spl above */ 4060 splx(s); 4061 } 4062 4063 void 4064 syn_cache_unreach(const struct sockaddr *src, const struct sockaddr *dst, 4065 struct tcphdr *th) 4066 { 4067 struct syn_cache *sc; 4068 struct syn_cache_head *scp; 4069 int s; 4070 4071 s = splsoftnet(); 4072 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 4073 splx(s); 4074 return; 4075 } 4076 /* If the sequence number != sc_iss, then it's a bogus ICMP msg */ 4077 if (ntohl(th->th_seq) != sc->sc_iss) { 4078 splx(s); 4079 return; 4080 } 4081 4082 /* 4083 * If we've retransmitted 3 times and this is our second error, 4084 * we remove the entry. Otherwise, we allow it to continue on. 4085 * This prevents us from incorrectly nuking an entry during a 4086 * spurious network outage. 4087 * 4088 * See tcp_notify(). 4089 */ 4090 if ((sc->sc_flags & SCF_UNREACH) == 0 || sc->sc_rxtshift < 3) { 4091 sc->sc_flags |= SCF_UNREACH; 4092 splx(s); 4093 return; 4094 } 4095 4096 syn_cache_rm(sc); 4097 TCP_STATINC(TCP_STAT_SC_UNREACH); 4098 syn_cache_put(sc); /* calls pool_put but see spl above */ 4099 splx(s); 4100 } 4101 4102 /* 4103 * Given a LISTEN socket and an inbound SYN request, add this to the syn 4104 * cache, and send back a segment: 4105 * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK> 4106 * to the source. 4107 * 4108 * IMPORTANT NOTE: We do _NOT_ ACK data that might accompany the SYN. 4109 * Doing so would require that we hold onto the data and deliver it 4110 * to the application. However, if we are the target of a SYN-flood 4111 * DoS attack, an attacker could send data which would eventually 4112 * consume all available buffer space if it were ACKed. By not ACKing 4113 * the data, we avoid this DoS scenario. 4114 */ 4115 int 4116 syn_cache_add(struct sockaddr *src, struct sockaddr *dst, struct tcphdr *th, 4117 unsigned int toff, struct socket *so, struct mbuf *m, u_char *optp, 4118 int optlen, struct tcp_opt_info *oi) 4119 { 4120 struct tcpcb tb, *tp; 4121 long win; 4122 struct syn_cache *sc; 4123 struct syn_cache_head *scp; 4124 struct mbuf *ipopts; 4125 int s; 4126 4127 tp = sototcpcb(so); 4128 4129 /* 4130 * Initialize some local state. 4131 */ 4132 win = sbspace(&so->so_rcv); 4133 if (win > TCP_MAXWIN) 4134 win = TCP_MAXWIN; 4135 4136 #ifdef TCP_SIGNATURE 4137 if (optp || (tp->t_flags & TF_SIGNATURE)) 4138 #else 4139 if (optp) 4140 #endif 4141 { 4142 tb.t_flags = tcp_do_rfc1323 ? (TF_REQ_SCALE|TF_REQ_TSTMP) : 0; 4143 #ifdef TCP_SIGNATURE 4144 tb.t_flags |= (tp->t_flags & TF_SIGNATURE); 4145 #endif 4146 tb.t_state = TCPS_LISTEN; 4147 if (tcp_dooptions(&tb, optp, optlen, th, m, toff, oi) < 0) 4148 return 0; 4149 } else 4150 tb.t_flags = 0; 4151 4152 switch (src->sa_family) { 4153 case AF_INET: 4154 /* Remember the IP options, if any. */ 4155 ipopts = ip_srcroute(m); 4156 break; 4157 default: 4158 ipopts = NULL; 4159 } 4160 4161 /* 4162 * See if we already have an entry for this connection. 4163 * If we do, resend the SYN,ACK. We do not count this 4164 * as a retransmission (XXX though maybe we should). 4165 */ 4166 if ((sc = syn_cache_lookup(src, dst, &scp)) != NULL) { 4167 TCP_STATINC(TCP_STAT_SC_DUPESYN); 4168 if (ipopts) { 4169 /* 4170 * If we were remembering a previous source route, 4171 * forget it and use the new one we've been given. 4172 */ 4173 if (sc->sc_ipopts) 4174 (void)m_free(sc->sc_ipopts); 4175 sc->sc_ipopts = ipopts; 4176 } 4177 sc->sc_timestamp = tb.ts_recent; 4178 m_freem(m); 4179 if (syn_cache_respond(sc) == 0) { 4180 uint64_t *tcps = TCP_STAT_GETREF(); 4181 tcps[TCP_STAT_SNDACKS]++; 4182 tcps[TCP_STAT_SNDTOTAL]++; 4183 TCP_STAT_PUTREF(); 4184 } 4185 return 1; 4186 } 4187 4188 s = splsoftnet(); 4189 sc = pool_get(&syn_cache_pool, PR_NOWAIT); 4190 splx(s); 4191 if (sc == NULL) { 4192 if (ipopts) 4193 (void)m_free(ipopts); 4194 return 0; 4195 } 4196 4197 /* 4198 * Fill in the cache, and put the necessary IP and TCP 4199 * options into the reply. 4200 */ 4201 memset(sc, 0, sizeof(struct syn_cache)); 4202 callout_init(&sc->sc_timer, CALLOUT_MPSAFE); 4203 memcpy(&sc->sc_src, src, src->sa_len); 4204 memcpy(&sc->sc_dst, dst, dst->sa_len); 4205 sc->sc_flags = 0; 4206 sc->sc_ipopts = ipopts; 4207 sc->sc_irs = th->th_seq; 4208 switch (src->sa_family) { 4209 case AF_INET: 4210 { 4211 struct sockaddr_in *srcin = (void *)src; 4212 struct sockaddr_in *dstin = (void *)dst; 4213 4214 sc->sc_iss = tcp_new_iss1(&dstin->sin_addr, 4215 &srcin->sin_addr, dstin->sin_port, 4216 srcin->sin_port, sizeof(dstin->sin_addr), 0); 4217 break; 4218 } 4219 #ifdef INET6 4220 case AF_INET6: 4221 { 4222 struct sockaddr_in6 *srcin6 = (void *)src; 4223 struct sockaddr_in6 *dstin6 = (void *)dst; 4224 4225 sc->sc_iss = tcp_new_iss1(&dstin6->sin6_addr, 4226 &srcin6->sin6_addr, dstin6->sin6_port, 4227 srcin6->sin6_port, sizeof(dstin6->sin6_addr), 0); 4228 break; 4229 } 4230 #endif 4231 } 4232 sc->sc_peermaxseg = oi->maxseg; 4233 sc->sc_ourmaxseg = tcp_mss_to_advertise(m->m_flags & M_PKTHDR ? 4234 m_get_rcvif_NOMPSAFE(m) : NULL, sc->sc_src.sa.sa_family); 4235 sc->sc_win = win; 4236 sc->sc_timebase = tcp_now - 1; /* see tcp_newtcpcb() */ 4237 sc->sc_timestamp = tb.ts_recent; 4238 if ((tb.t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP)) == 4239 (TF_REQ_TSTMP|TF_RCVD_TSTMP)) 4240 sc->sc_flags |= SCF_TIMESTAMP; 4241 if ((tb.t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 4242 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 4243 sc->sc_requested_s_scale = tb.requested_s_scale; 4244 sc->sc_request_r_scale = 0; 4245 /* 4246 * Pick the smallest possible scaling factor that 4247 * will still allow us to scale up to sb_max. 4248 * 4249 * We do this because there are broken firewalls that 4250 * will corrupt the window scale option, leading to 4251 * the other endpoint believing that our advertised 4252 * window is unscaled. At scale factors larger than 4253 * 5 the unscaled window will drop below 1500 bytes, 4254 * leading to serious problems when traversing these 4255 * broken firewalls. 4256 * 4257 * With the default sbmax of 256K, a scale factor 4258 * of 3 will be chosen by this algorithm. Those who 4259 * choose a larger sbmax should watch out 4260 * for the compatiblity problems mentioned above. 4261 * 4262 * RFC1323: The Window field in a SYN (i.e., a <SYN> 4263 * or <SYN,ACK>) segment itself is never scaled. 4264 */ 4265 while (sc->sc_request_r_scale < TCP_MAX_WINSHIFT && 4266 (TCP_MAXWIN << sc->sc_request_r_scale) < sb_max) 4267 sc->sc_request_r_scale++; 4268 } else { 4269 sc->sc_requested_s_scale = 15; 4270 sc->sc_request_r_scale = 15; 4271 } 4272 if ((tb.t_flags & TF_SACK_PERMIT) && tcp_do_sack) 4273 sc->sc_flags |= SCF_SACK_PERMIT; 4274 4275 /* 4276 * ECN setup packet received. 4277 */ 4278 if ((th->th_flags & (TH_ECE|TH_CWR)) && tcp_do_ecn) 4279 sc->sc_flags |= SCF_ECN_PERMIT; 4280 4281 #ifdef TCP_SIGNATURE 4282 if (tb.t_flags & TF_SIGNATURE) 4283 sc->sc_flags |= SCF_SIGNATURE; 4284 #endif 4285 sc->sc_tp = tp; 4286 m_freem(m); 4287 if (syn_cache_respond(sc) == 0) { 4288 uint64_t *tcps = TCP_STAT_GETREF(); 4289 tcps[TCP_STAT_SNDACKS]++; 4290 tcps[TCP_STAT_SNDTOTAL]++; 4291 TCP_STAT_PUTREF(); 4292 syn_cache_insert(sc, tp); 4293 } else { 4294 s = splsoftnet(); 4295 /* 4296 * syn_cache_put() will try to schedule the timer, so 4297 * we need to initialize it 4298 */ 4299 syn_cache_timer_arm(sc); 4300 syn_cache_put(sc); 4301 splx(s); 4302 TCP_STATINC(TCP_STAT_SC_DROPPED); 4303 } 4304 return 1; 4305 } 4306 4307 /* 4308 * syn_cache_respond: (re)send SYN+ACK. 4309 * 4310 * Returns 0 on success. 4311 */ 4312 4313 int 4314 syn_cache_respond(struct syn_cache *sc) 4315 { 4316 #ifdef INET6 4317 struct rtentry *rt = NULL; 4318 #endif 4319 struct route *ro; 4320 u_int8_t *optp; 4321 int optlen, error; 4322 u_int16_t tlen; 4323 struct ip *ip = NULL; 4324 #ifdef INET6 4325 struct ip6_hdr *ip6 = NULL; 4326 #endif 4327 struct tcpcb *tp; 4328 struct tcphdr *th; 4329 struct mbuf *m; 4330 u_int hlen; 4331 #ifdef TCP_SIGNATURE 4332 struct secasvar *sav = NULL; 4333 u_int8_t *sigp = NULL; 4334 #endif 4335 4336 ro = &sc->sc_route; 4337 switch (sc->sc_src.sa.sa_family) { 4338 case AF_INET: 4339 hlen = sizeof(struct ip); 4340 break; 4341 #ifdef INET6 4342 case AF_INET6: 4343 hlen = sizeof(struct ip6_hdr); 4344 break; 4345 #endif 4346 default: 4347 return EAFNOSUPPORT; 4348 } 4349 4350 /* Worst case scanario, since we don't know the option size yet. */ 4351 tlen = hlen + sizeof(struct tcphdr) + MAX_TCPOPTLEN; 4352 KASSERT(max_linkhdr + tlen <= MCLBYTES); 4353 4354 /* 4355 * Create the IP+TCP header from scratch. 4356 */ 4357 MGETHDR(m, M_DONTWAIT, MT_DATA); 4358 if (m && (max_linkhdr + tlen) > MHLEN) { 4359 MCLGET(m, M_DONTWAIT); 4360 if ((m->m_flags & M_EXT) == 0) { 4361 m_freem(m); 4362 m = NULL; 4363 } 4364 } 4365 if (m == NULL) 4366 return ENOBUFS; 4367 MCLAIM(m, &tcp_tx_mowner); 4368 4369 tp = sc->sc_tp; 4370 4371 /* Fixup the mbuf. */ 4372 m->m_data += max_linkhdr; 4373 m_reset_rcvif(m); 4374 memset(mtod(m, void *), 0, tlen); 4375 4376 switch (sc->sc_src.sa.sa_family) { 4377 case AF_INET: 4378 ip = mtod(m, struct ip *); 4379 ip->ip_v = 4; 4380 ip->ip_dst = sc->sc_src.sin.sin_addr; 4381 ip->ip_src = sc->sc_dst.sin.sin_addr; 4382 ip->ip_p = IPPROTO_TCP; 4383 th = (struct tcphdr *)(ip + 1); 4384 th->th_dport = sc->sc_src.sin.sin_port; 4385 th->th_sport = sc->sc_dst.sin.sin_port; 4386 break; 4387 #ifdef INET6 4388 case AF_INET6: 4389 ip6 = mtod(m, struct ip6_hdr *); 4390 ip6->ip6_vfc = IPV6_VERSION; 4391 ip6->ip6_dst = sc->sc_src.sin6.sin6_addr; 4392 ip6->ip6_src = sc->sc_dst.sin6.sin6_addr; 4393 ip6->ip6_nxt = IPPROTO_TCP; 4394 /* ip6_plen will be updated in ip6_output() */ 4395 th = (struct tcphdr *)(ip6 + 1); 4396 th->th_dport = sc->sc_src.sin6.sin6_port; 4397 th->th_sport = sc->sc_dst.sin6.sin6_port; 4398 break; 4399 #endif 4400 default: 4401 panic("%s: impossible (1)", __func__); 4402 } 4403 4404 th->th_seq = htonl(sc->sc_iss); 4405 th->th_ack = htonl(sc->sc_irs + 1); 4406 th->th_flags = TH_SYN|TH_ACK; 4407 th->th_win = htons(sc->sc_win); 4408 /* th_x2, th_sum, th_urp already 0 from memset */ 4409 4410 /* Tack on the TCP options. */ 4411 optp = (u_int8_t *)(th + 1); 4412 optlen = 0; 4413 *optp++ = TCPOPT_MAXSEG; 4414 *optp++ = TCPOLEN_MAXSEG; 4415 *optp++ = (sc->sc_ourmaxseg >> 8) & 0xff; 4416 *optp++ = sc->sc_ourmaxseg & 0xff; 4417 optlen += TCPOLEN_MAXSEG; 4418 4419 if (sc->sc_request_r_scale != 15) { 4420 *((u_int32_t *)optp) = htonl(TCPOPT_NOP << 24 | 4421 TCPOPT_WINDOW << 16 | TCPOLEN_WINDOW << 8 | 4422 sc->sc_request_r_scale); 4423 optp += TCPOLEN_WINDOW + TCPOLEN_NOP; 4424 optlen += TCPOLEN_WINDOW + TCPOLEN_NOP; 4425 } 4426 4427 if (sc->sc_flags & SCF_SACK_PERMIT) { 4428 /* Let the peer know that we will SACK. */ 4429 *optp++ = TCPOPT_SACK_PERMITTED; 4430 *optp++ = TCPOLEN_SACK_PERMITTED; 4431 optlen += TCPOLEN_SACK_PERMITTED; 4432 } 4433 4434 if (sc->sc_flags & SCF_TIMESTAMP) { 4435 while (optlen % 4 != 2) { 4436 optlen += TCPOLEN_NOP; 4437 *optp++ = TCPOPT_NOP; 4438 } 4439 *optp++ = TCPOPT_TIMESTAMP; 4440 *optp++ = TCPOLEN_TIMESTAMP; 4441 u_int32_t *lp = (u_int32_t *)(optp); 4442 /* Form timestamp option as shown in appendix A of RFC 1323. */ 4443 *lp++ = htonl(SYN_CACHE_TIMESTAMP(sc)); 4444 *lp = htonl(sc->sc_timestamp); 4445 optp += TCPOLEN_TIMESTAMP - 2; 4446 optlen += TCPOLEN_TIMESTAMP; 4447 } 4448 4449 #ifdef TCP_SIGNATURE 4450 if (sc->sc_flags & SCF_SIGNATURE) { 4451 sav = tcp_signature_getsav(m); 4452 if (sav == NULL) { 4453 m_freem(m); 4454 return EPERM; 4455 } 4456 4457 *optp++ = TCPOPT_SIGNATURE; 4458 *optp++ = TCPOLEN_SIGNATURE; 4459 sigp = optp; 4460 memset(optp, 0, TCP_SIGLEN); 4461 optp += TCP_SIGLEN; 4462 optlen += TCPOLEN_SIGNATURE; 4463 } 4464 #endif 4465 4466 /* 4467 * Terminate and pad TCP options to a 4 byte boundary. 4468 * 4469 * According to RFC793: "The content of the header beyond the 4470 * End-of-Option option must be header padding (i.e., zero)." 4471 * And later: "The padding is composed of zeros." 4472 */ 4473 if (optlen % 4) { 4474 optlen += TCPOLEN_EOL; 4475 *optp++ = TCPOPT_EOL; 4476 } 4477 while (optlen % 4) { 4478 optlen += TCPOLEN_PAD; 4479 *optp++ = TCPOPT_PAD; 4480 } 4481 4482 /* Compute the actual values now that we've added the options. */ 4483 tlen = hlen + sizeof(struct tcphdr) + optlen; 4484 m->m_len = m->m_pkthdr.len = tlen; 4485 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 4486 4487 #ifdef TCP_SIGNATURE 4488 if (sav) { 4489 (void)tcp_signature(m, th, hlen, sav, sigp); 4490 key_sa_recordxfer(sav, m); 4491 KEY_SA_UNREF(&sav); 4492 } 4493 #endif 4494 4495 /* 4496 * Send ECN SYN-ACK setup packet. 4497 * Routes can be asymetric, so, even if we receive a packet 4498 * with ECE and CWR set, we must not assume no one will block 4499 * the ECE packet we are about to send. 4500 */ 4501 if ((sc->sc_flags & SCF_ECN_PERMIT) && tp && 4502 SEQ_GEQ(tp->snd_nxt, tp->snd_max)) { 4503 th->th_flags |= TH_ECE; 4504 TCP_STATINC(TCP_STAT_ECN_SHS); 4505 4506 /* 4507 * draft-ietf-tcpm-ecnsyn-00.txt 4508 * 4509 * "[...] a TCP node MAY respond to an ECN-setup 4510 * SYN packet by setting ECT in the responding 4511 * ECN-setup SYN/ACK packet, indicating to routers 4512 * that the SYN/ACK packet is ECN-Capable. 4513 * This allows a congested router along the path 4514 * to mark the packet instead of dropping the 4515 * packet as an indication of congestion." 4516 * 4517 * "[...] There can be a great benefit in setting 4518 * an ECN-capable codepoint in SYN/ACK packets [...] 4519 * Congestion is most likely to occur in 4520 * the server-to-client direction. As a result, 4521 * setting an ECN-capable codepoint in SYN/ACK 4522 * packets can reduce the occurence of three-second 4523 * retransmit timeouts resulting from the drop 4524 * of SYN/ACK packets." 4525 * 4526 * Page 4 and 6, January 2006. 4527 */ 4528 4529 switch (sc->sc_src.sa.sa_family) { 4530 case AF_INET: 4531 ip->ip_tos |= IPTOS_ECN_ECT0; 4532 break; 4533 #ifdef INET6 4534 case AF_INET6: 4535 ip6->ip6_flow |= htonl(IPTOS_ECN_ECT0 << 20); 4536 break; 4537 #endif 4538 } 4539 TCP_STATINC(TCP_STAT_ECN_ECT); 4540 } 4541 4542 4543 /* 4544 * Compute the packet's checksum. 4545 * 4546 * Fill in some straggling IP bits. Note the stack expects 4547 * ip_len to be in host order, for convenience. 4548 */ 4549 switch (sc->sc_src.sa.sa_family) { 4550 case AF_INET: 4551 ip->ip_len = htons(tlen - hlen); 4552 th->th_sum = 0; 4553 th->th_sum = in4_cksum(m, IPPROTO_TCP, hlen, tlen - hlen); 4554 ip->ip_len = htons(tlen); 4555 ip->ip_ttl = ip_defttl; 4556 /* XXX tos? */ 4557 break; 4558 #ifdef INET6 4559 case AF_INET6: 4560 ip6->ip6_plen = htons(tlen - hlen); 4561 th->th_sum = 0; 4562 th->th_sum = in6_cksum(m, IPPROTO_TCP, hlen, tlen - hlen); 4563 ip6->ip6_vfc &= ~IPV6_VERSION_MASK; 4564 ip6->ip6_vfc |= IPV6_VERSION; 4565 ip6->ip6_plen = htons(tlen - hlen); 4566 /* ip6_hlim will be initialized afterwards */ 4567 /* XXX flowlabel? */ 4568 break; 4569 #endif 4570 } 4571 4572 /* XXX use IPsec policy on listening socket, on SYN ACK */ 4573 tp = sc->sc_tp; 4574 4575 switch (sc->sc_src.sa.sa_family) { 4576 case AF_INET: 4577 error = ip_output(m, sc->sc_ipopts, ro, 4578 (ip_mtudisc ? IP_MTUDISC : 0), 4579 NULL, tp ? tp->t_inpcb : NULL); 4580 break; 4581 #ifdef INET6 4582 case AF_INET6: 4583 ip6->ip6_hlim = in6_selecthlim(NULL, 4584 (rt = rtcache_validate(ro)) != NULL ? rt->rt_ifp : NULL); 4585 rtcache_unref(rt, ro); 4586 4587 error = ip6_output(m, NULL /*XXX*/, ro, 0, NULL, 4588 tp ? tp->t_in6pcb : NULL, NULL); 4589 break; 4590 #endif 4591 default: 4592 panic("%s: impossible (2)", __func__); 4593 } 4594 4595 return error; 4596 } 4597