tcp_input.c revision 1.92
1 /* $NetBSD: tcp_input.c,v 1.92 1999/08/23 14:14:30 christos Exp $ */ 2 3 /* 4 %%% portions-copyright-nrl-95 5 Portions of this software are Copyright 1995-1998 by Randall Atkinson, 6 Ronald Lee, Daniel McDonald, Bao Phan, and Chris Winters. All Rights 7 Reserved. All rights under this copyright have been assigned to the US 8 Naval Research Laboratory (NRL). The NRL Copyright Notice and License 9 Agreement Version 1.1 (January 17, 1995) applies to these portions of the 10 software. 11 You should have received a copy of the license with this software. If you 12 didn't get a copy, you may request one from <license (at) ipv6.nrl.navy.mil>. 13 14 */ 15 16 /* 17 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. 18 * All rights reserved. 19 * 20 * Redistribution and use in source and binary forms, with or without 21 * modification, are permitted provided that the following conditions 22 * are met: 23 * 1. Redistributions of source code must retain the above copyright 24 * notice, this list of conditions and the following disclaimer. 25 * 2. Redistributions in binary form must reproduce the above copyright 26 * notice, this list of conditions and the following disclaimer in the 27 * documentation and/or other materials provided with the distribution. 28 * 3. Neither the name of the project nor the names of its contributors 29 * may be used to endorse or promote products derived from this software 30 * without specific prior written permission. 31 * 32 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND 33 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 34 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 35 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE 36 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 37 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 38 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 39 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 40 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 41 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 42 * SUCH DAMAGE. 43 */ 44 45 /*- 46 * Copyright (c) 1997, 1998, 1999 The NetBSD Foundation, Inc. 47 * All rights reserved. 48 * 49 * This code is derived from software contributed to The NetBSD Foundation 50 * by Jason R. Thorpe and Kevin M. Lahey of the Numerical Aerospace Simulation 51 * Facility, NASA Ames Research Center. 52 * 53 * Redistribution and use in source and binary forms, with or without 54 * modification, are permitted provided that the following conditions 55 * are met: 56 * 1. Redistributions of source code must retain the above copyright 57 * notice, this list of conditions and the following disclaimer. 58 * 2. Redistributions in binary form must reproduce the above copyright 59 * notice, this list of conditions and the following disclaimer in the 60 * documentation and/or other materials provided with the distribution. 61 * 3. All advertising materials mentioning features or use of this software 62 * must display the following acknowledgement: 63 * This product includes software developed by the NetBSD 64 * Foundation, Inc. and its contributors. 65 * 4. Neither the name of The NetBSD Foundation nor the names of its 66 * contributors may be used to endorse or promote products derived 67 * from this software without specific prior written permission. 68 * 69 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 70 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 71 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 72 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 73 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 74 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 75 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 76 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 77 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 78 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 79 * POSSIBILITY OF SUCH DAMAGE. 80 */ 81 82 /* 83 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995 84 * The Regents of the University of California. All rights reserved. 85 * 86 * Redistribution and use in source and binary forms, with or without 87 * modification, are permitted provided that the following conditions 88 * are met: 89 * 1. Redistributions of source code must retain the above copyright 90 * notice, this list of conditions and the following disclaimer. 91 * 2. Redistributions in binary form must reproduce the above copyright 92 * notice, this list of conditions and the following disclaimer in the 93 * documentation and/or other materials provided with the distribution. 94 * 3. All advertising materials mentioning features or use of this software 95 * must display the following acknowledgement: 96 * This product includes software developed by the University of 97 * California, Berkeley and its contributors. 98 * 4. Neither the name of the University nor the names of its contributors 99 * may be used to endorse or promote products derived from this software 100 * without specific prior written permission. 101 * 102 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 103 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 104 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 105 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 106 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 107 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 108 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 109 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 110 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 111 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 112 * SUCH DAMAGE. 113 * 114 * @(#)tcp_input.c 8.12 (Berkeley) 5/24/95 115 */ 116 117 /* 118 * TODO list for SYN cache stuff: 119 * 120 * Find room for a "state" field, which is needed to keep a 121 * compressed state for TIME_WAIT TCBs. It's been noted already 122 * that this is fairly important for very high-volume web and 123 * mail servers, which use a large number of short-lived 124 * connections. 125 */ 126 127 #include "opt_inet.h" 128 #include "opt_ipsec.h" 129 130 #include <sys/param.h> 131 #include <sys/systm.h> 132 #include <sys/malloc.h> 133 #include <sys/mbuf.h> 134 #include <sys/protosw.h> 135 #include <sys/socket.h> 136 #include <sys/socketvar.h> 137 #include <sys/errno.h> 138 #include <sys/syslog.h> 139 #include <sys/pool.h> 140 #include <sys/domain.h> 141 142 #include <net/if.h> 143 #include <net/route.h> 144 #include <net/if_types.h> 145 146 #include <netinet/in.h> 147 #include <netinet/in_systm.h> 148 #include <netinet/ip.h> 149 #include <netinet/in_pcb.h> 150 #include <netinet/ip_var.h> 151 152 #ifdef INET6 153 #ifndef INET 154 #include <netinet/in.h> 155 #endif 156 #include <netinet/ip6.h> 157 #include <netinet6/in6_pcb.h> 158 #include <netinet6/ip6_var.h> 159 #include <netinet6/in6_var.h> 160 #include <netinet/icmp6.h> 161 #endif 162 163 #include <netinet/tcp.h> 164 #include <netinet/tcp_fsm.h> 165 #include <netinet/tcp_seq.h> 166 #include <netinet/tcp_timer.h> 167 #include <netinet/tcp_var.h> 168 #include <netinet/tcpip.h> 169 #include <netinet/tcp_debug.h> 170 171 #include <machine/stdarg.h> 172 173 #ifdef IPSEC 174 #include <netinet6/ipsec.h> 175 #include <netkey/key.h> 176 #include <netkey/key_debug.h> 177 #endif /*IPSEC*/ 178 #ifdef INET6 179 #include "faith.h" 180 #endif 181 182 int tcprexmtthresh = 3; 183 int tcp_log_refused; 184 185 #define TCP_PAWS_IDLE (24 * 24 * 60 * 60 * PR_SLOWHZ) 186 187 /* for modulo comparisons of timestamps */ 188 #define TSTMP_LT(a,b) ((int)((a)-(b)) < 0) 189 #define TSTMP_GEQ(a,b) ((int)((a)-(b)) >= 0) 190 191 /* 192 * Macro to compute ACK transmission behavior. Delay the ACK unless 193 * we have already delayed an ACK (must send an ACK every two segments). 194 * We also ACK immediately if we received a PUSH and the ACK-on-PUSH 195 * option is enabled. 196 */ 197 #define TCP_SETUP_ACK(tp, th) \ 198 do { \ 199 if ((tp)->t_flags & TF_DELACK || \ 200 (tcp_ack_on_push && (th)->th_flags & TH_PUSH)) \ 201 tp->t_flags |= TF_ACKNOW; \ 202 else \ 203 TCP_SET_DELACK(tp); \ 204 } while (0) 205 206 int 207 tcp_reass(tp, th, m, tlen) 208 register struct tcpcb *tp; 209 register struct tcphdr *th; 210 struct mbuf *m; 211 int *tlen; 212 { 213 register struct ipqent *p, *q, *nq, *tiqe = NULL; 214 struct socket *so = NULL; 215 int pkt_flags; 216 tcp_seq pkt_seq; 217 unsigned pkt_len; 218 u_long rcvpartdupbyte = 0; 219 u_long rcvoobyte; 220 221 if (tp->t_inpcb) 222 so = tp->t_inpcb->inp_socket; 223 #ifdef INET6 224 else if (tp->t_in6pcb) 225 so = tp->t_in6pcb->in6p_socket; 226 #endif 227 228 TCP_REASS_LOCK_CHECK(tp); 229 230 /* 231 * Call with th==0 after become established to 232 * force pre-ESTABLISHED data up to user socket. 233 */ 234 if (th == 0) 235 goto present; 236 237 rcvoobyte = *tlen; 238 /* 239 * Copy these to local variables because the tcpiphdr 240 * gets munged while we are collapsing mbufs. 241 */ 242 pkt_seq = th->th_seq; 243 pkt_len = *tlen; 244 pkt_flags = th->th_flags; 245 /* 246 * Find a segment which begins after this one does. 247 */ 248 for (p = NULL, q = tp->segq.lh_first; q != NULL; q = nq) { 249 nq = q->ipqe_q.le_next; 250 /* 251 * If the received segment is just right after this 252 * fragment, merge the two together and then check 253 * for further overlaps. 254 */ 255 if (q->ipqe_seq + q->ipqe_len == pkt_seq) { 256 #ifdef TCPREASS_DEBUG 257 printf("tcp_reass[%p]: concat %u:%u(%u) to %u:%u(%u)\n", 258 tp, pkt_seq, pkt_seq + pkt_len, pkt_len, 259 q->ipqe_seq, q->ipqe_seq + q->ipqe_len, q->ipqe_len); 260 #endif 261 pkt_len += q->ipqe_len; 262 pkt_flags |= q->ipqe_flags; 263 pkt_seq = q->ipqe_seq; 264 m_cat(q->ipqe_m, m); 265 m = q->ipqe_m; 266 goto free_ipqe; 267 } 268 /* 269 * If the received segment is completely past this 270 * fragment, we need to go the next fragment. 271 */ 272 if (SEQ_LT(q->ipqe_seq + q->ipqe_len, pkt_seq)) { 273 p = q; 274 continue; 275 } 276 /* 277 * If the fragment is past the received segment, 278 * it (or any following) can't be concatenated. 279 */ 280 if (SEQ_GT(q->ipqe_seq, pkt_seq + pkt_len)) 281 break; 282 /* 283 * We've received all the data in this segment before. 284 * mark it as a duplicate and return. 285 */ 286 if (SEQ_LEQ(q->ipqe_seq, pkt_seq) && 287 SEQ_GEQ(q->ipqe_seq + q->ipqe_len, pkt_seq + pkt_len)) { 288 tcpstat.tcps_rcvduppack++; 289 tcpstat.tcps_rcvdupbyte += pkt_len; 290 m_freem(m); 291 if (tiqe != NULL) 292 pool_put(&ipqent_pool, tiqe); 293 return (0); 294 } 295 /* 296 * Received segment completely overlaps this fragment 297 * so we drop the fragment (this keeps the temporal 298 * ordering of segments correct). 299 */ 300 if (SEQ_GEQ(q->ipqe_seq, pkt_seq) && 301 SEQ_LEQ(q->ipqe_seq + q->ipqe_len, pkt_seq + pkt_len)) { 302 rcvpartdupbyte += q->ipqe_len; 303 m_freem(q->ipqe_m); 304 goto free_ipqe; 305 } 306 /* 307 * RX'ed segment extends past the end of the 308 * fragment. Drop the overlapping bytes. Then 309 * merge the fragment and segment then treat as 310 * a longer received packet. 311 */ 312 if (SEQ_LT(q->ipqe_seq, pkt_seq) 313 && SEQ_GT(q->ipqe_seq + q->ipqe_len, pkt_seq)) { 314 int overlap = q->ipqe_seq + q->ipqe_len - pkt_seq; 315 #ifdef TCPREASS_DEBUG 316 printf("tcp_reass[%p]: trim starting %d bytes of %u:%u(%u)\n", 317 tp, overlap, 318 pkt_seq, pkt_seq + pkt_len, pkt_len); 319 #endif 320 m_adj(m, overlap); 321 rcvpartdupbyte += overlap; 322 m_cat(q->ipqe_m, m); 323 m = q->ipqe_m; 324 pkt_seq = q->ipqe_seq; 325 pkt_len += q->ipqe_len - overlap; 326 rcvoobyte -= overlap; 327 goto free_ipqe; 328 } 329 /* 330 * RX'ed segment extends past the front of the 331 * fragment. Drop the overlapping bytes on the 332 * received packet. The packet will then be 333 * contatentated with this fragment a bit later. 334 */ 335 if (SEQ_GT(q->ipqe_seq, pkt_seq) 336 && SEQ_LT(q->ipqe_seq, pkt_seq + pkt_len)) { 337 int overlap = pkt_seq + pkt_len - q->ipqe_seq; 338 #ifdef TCPREASS_DEBUG 339 printf("tcp_reass[%p]: trim trailing %d bytes of %u:%u(%u)\n", 340 tp, overlap, 341 pkt_seq, pkt_seq + pkt_len, pkt_len); 342 #endif 343 m_adj(m, -overlap); 344 pkt_len -= overlap; 345 rcvpartdupbyte += overlap; 346 rcvoobyte -= overlap; 347 } 348 /* 349 * If the received segment immediates precedes this 350 * fragment then tack the fragment onto this segment 351 * and reinsert the data. 352 */ 353 if (q->ipqe_seq == pkt_seq + pkt_len) { 354 #ifdef TCPREASS_DEBUG 355 printf("tcp_reass[%p]: append %u:%u(%u) to %u:%u(%u)\n", 356 tp, q->ipqe_seq, q->ipqe_seq + q->ipqe_len, q->ipqe_len, 357 pkt_seq, pkt_seq + pkt_len, pkt_len); 358 #endif 359 pkt_len += q->ipqe_len; 360 pkt_flags |= q->ipqe_flags; 361 m_cat(m, q->ipqe_m); 362 LIST_REMOVE(q, ipqe_q); 363 LIST_REMOVE(q, ipqe_timeq); 364 if (tiqe == NULL) { 365 tiqe = q; 366 } else { 367 pool_put(&ipqent_pool, q); 368 } 369 break; 370 } 371 /* 372 * If the fragment is before the segment, remember it. 373 * When this loop is terminated, p will contain the 374 * pointer to fragment that is right before the received 375 * segment. 376 */ 377 if (SEQ_LEQ(q->ipqe_seq, pkt_seq)) 378 p = q; 379 380 continue; 381 382 /* 383 * This is a common operation. It also will allow 384 * to save doing a malloc/free in most instances. 385 */ 386 free_ipqe: 387 LIST_REMOVE(q, ipqe_q); 388 LIST_REMOVE(q, ipqe_timeq); 389 if (tiqe == NULL) { 390 tiqe = q; 391 } else { 392 pool_put(&ipqent_pool, q); 393 } 394 } 395 396 /* 397 * Allocate a new queue entry since the received segment did not 398 * collapse onto any other out-of-order block; thus we are allocating 399 * a new block. If it had collapsed, tiqe would not be NULL and 400 * we would be reusing it. 401 * XXX If we can't, just drop the packet. XXX 402 */ 403 if (tiqe == NULL) { 404 tiqe = pool_get(&ipqent_pool, PR_NOWAIT); 405 if (tiqe == NULL) { 406 tcpstat.tcps_rcvmemdrop++; 407 m_freem(m); 408 return (0); 409 } 410 } 411 412 /* 413 * Update the counters. 414 */ 415 tcpstat.tcps_rcvoopack++; 416 tcpstat.tcps_rcvoobyte += rcvoobyte; 417 if (rcvpartdupbyte) { 418 tcpstat.tcps_rcvpartduppack++; 419 tcpstat.tcps_rcvpartdupbyte += rcvpartdupbyte; 420 } 421 422 /* 423 * Insert the new fragment queue entry into both queues. 424 */ 425 tiqe->ipqe_m = m; 426 tiqe->ipqe_seq = pkt_seq; 427 tiqe->ipqe_len = pkt_len; 428 tiqe->ipqe_flags = pkt_flags; 429 if (p == NULL) { 430 LIST_INSERT_HEAD(&tp->segq, tiqe, ipqe_q); 431 #ifdef TCPREASS_DEBUG 432 if (tiqe->ipqe_seq != tp->rcv_nxt) 433 printf("tcp_reass[%p]: insert %u:%u(%u) at front\n", 434 tp, pkt_seq, pkt_seq + pkt_len, pkt_len); 435 #endif 436 } else { 437 LIST_INSERT_AFTER(p, tiqe, ipqe_q); 438 #ifdef TCPREASS_DEBUG 439 printf("tcp_reass[%p]: insert %u:%u(%u) after %u:%u(%u)\n", 440 tp, pkt_seq, pkt_seq + pkt_len, pkt_len, 441 p->ipqe_seq, p->ipqe_seq + p->ipqe_len, p->ipqe_len); 442 #endif 443 } 444 445 LIST_INSERT_HEAD(&tp->timeq, tiqe, ipqe_timeq); 446 447 present: 448 /* 449 * Present data to user, advancing rcv_nxt through 450 * completed sequence space. 451 */ 452 if (TCPS_HAVEESTABLISHED(tp->t_state) == 0) 453 return (0); 454 q = tp->segq.lh_first; 455 if (q == NULL || q->ipqe_seq != tp->rcv_nxt) 456 return (0); 457 if (tp->t_state == TCPS_SYN_RECEIVED && q->ipqe_len) 458 return (0); 459 460 tp->rcv_nxt += q->ipqe_len; 461 pkt_flags = q->ipqe_flags & TH_FIN; 462 463 LIST_REMOVE(q, ipqe_q); 464 LIST_REMOVE(q, ipqe_timeq); 465 if (so->so_state & SS_CANTRCVMORE) 466 m_freem(q->ipqe_m); 467 else 468 sbappend(&so->so_rcv, q->ipqe_m); 469 pool_put(&ipqent_pool, q); 470 sorwakeup(so); 471 return (pkt_flags); 472 } 473 474 #if defined(INET6) && !defined(TCP6) 475 int 476 tcp6_input(mp, offp, proto) 477 struct mbuf **mp; 478 int *offp, proto; 479 { 480 struct mbuf *m = *mp; 481 482 #if defined(NFAITH) && 0 < NFAITH 483 if (m->m_pkthdr.rcvif) { 484 if (m->m_pkthdr.rcvif->if_type == IFT_FAITH) { 485 /* XXX send icmp6 host/port unreach? */ 486 m_freem(m); 487 return IPPROTO_DONE; 488 } 489 } 490 #endif 491 492 /* 493 * draft-itojun-ipv6-tcp-to-anycast 494 * better place to put this in? 495 */ 496 if (m->m_flags & M_ANYCAST6) { 497 if (m->m_len >= sizeof(struct ip6_hdr)) { 498 struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *); 499 icmp6_error(m, ICMP6_DST_UNREACH, 500 ICMP6_DST_UNREACH_ADDR, 501 (caddr_t)&ip6->ip6_dst - (caddr_t)ip6); 502 } else 503 m_freem(m); 504 return IPPROTO_DONE; 505 } 506 507 tcp_input(m, *offp, proto); 508 return IPPROTO_DONE; 509 } 510 #endif 511 512 /* 513 * TCP input routine, follows pages 65-76 of the 514 * protocol specification dated September, 1981 very closely. 515 */ 516 void 517 #if __STDC__ 518 tcp_input(struct mbuf *m, ...) 519 #else 520 tcp_input(m, va_alist) 521 register struct mbuf *m; 522 #endif 523 { 524 int proto; 525 register struct tcphdr *th; 526 struct ip *ip; 527 register struct inpcb *inp; 528 #ifdef INET6 529 struct ip6_hdr *ip6; 530 register struct in6pcb *in6p; 531 #endif 532 caddr_t optp = NULL; 533 int optlen = 0; 534 int len, tlen, toff, hdroptlen = 0; 535 register struct tcpcb *tp = 0; 536 register int tiflags; 537 struct socket *so = NULL; 538 int todrop, acked, ourfinisacked, needoutput = 0; 539 short ostate = 0; 540 int iss = 0; 541 u_long tiwin; 542 struct tcp_opt_info opti; 543 int off, iphlen; 544 va_list ap; 545 int af; /* af on the wire */ 546 struct mbuf *tcp_saveti = NULL; 547 548 va_start(ap, m); 549 toff = va_arg(ap, int); 550 proto = va_arg(ap, int); 551 va_end(ap); 552 553 tcpstat.tcps_rcvtotal++; 554 555 bzero(&opti, sizeof(opti)); 556 opti.ts_present = 0; 557 opti.maxseg = 0; 558 559 /* 560 * Get IP and TCP header together in first mbuf. 561 * Note: IP leaves IP header in first mbuf. 562 */ 563 ip = mtod(m, struct ip *); 564 #ifdef INET6 565 ip6 = NULL; 566 #endif 567 switch (ip->ip_v) { 568 case 4: 569 af = AF_INET; 570 iphlen = sizeof(struct ip); 571 /* would like to get rid of this... */ 572 if (toff > sizeof (struct ip)) { 573 ip_stripoptions(m, (struct mbuf *)0); 574 toff = sizeof(struct ip); 575 } 576 if (m->m_len < toff + sizeof (struct tcphdr)) { 577 if ((m = m_pullup(m, toff + sizeof (struct tcphdr))) == 0) { 578 tcpstat.tcps_rcvshort++; 579 return; 580 } 581 } 582 ip = mtod(m, struct ip *); 583 th = (struct tcphdr *)(mtod(m, caddr_t) + toff); 584 585 /* 586 * Checksum extended TCP header and data. 587 */ 588 len = ip->ip_len; 589 tlen = len - toff; 590 { 591 struct ipovly *ipov; 592 ipov = (struct ipovly *)ip; 593 bzero(ipov->ih_x1, sizeof ipov->ih_x1); 594 ipov->ih_len = htons(tlen); 595 } 596 if (in_cksum(m, len) != 0) { 597 tcpstat.tcps_rcvbadsum++; 598 goto drop; 599 } 600 break; 601 #ifdef INET6 602 case 6: 603 ip = NULL; 604 iphlen = sizeof(struct ip6_hdr); 605 af = AF_INET6; 606 if (m->m_len < toff + sizeof(struct tcphdr)) { 607 m = m_pullup(m, toff + sizeof(struct tcphdr)); /*XXX*/ 608 if (m == NULL) { 609 tcpstat.tcps_rcvshort++; 610 return; 611 } 612 } 613 ip6 = mtod(m, struct ip6_hdr *); 614 th = (struct tcphdr *)(mtod(m, caddr_t) + toff); 615 616 /* 617 * Checksum extended TCP header and data. 618 */ 619 len = m->m_pkthdr.len; 620 tlen = len - toff; 621 if (in6_cksum(m, IPPROTO_TCP, toff, tlen)) { 622 tcpstat.tcps_rcvbadsum++; 623 goto drop; 624 } 625 break; 626 #endif 627 default: 628 m_freem(m); 629 return; 630 } 631 632 /* 633 * Check that TCP offset makes sense, 634 * pull out TCP options and adjust length. XXX 635 */ 636 off = th->th_off << 2; 637 if (off < sizeof (struct tcphdr) || off > tlen) { 638 tcpstat.tcps_rcvbadoff++; 639 goto drop; 640 } 641 tlen -= off; 642 643 /* 644 * tcp_input() has been modified to use tlen to mean the TCP data 645 * length throughout the function. Other functions can use 646 * m->m_pkthdr.len as the basis for calculating the TCP data length. 647 * rja 648 */ 649 650 if (off > sizeof (struct tcphdr)) { 651 if (m->m_len < toff + off) { 652 if ((m = m_pullup(m, toff + off)) == 0) { 653 tcpstat.tcps_rcvshort++; 654 return; 655 } 656 switch (af) { 657 case AF_INET: 658 ip = mtod(m, struct ip *); 659 break; 660 #ifdef INET6 661 case AF_INET6: 662 ip6 = mtod(m, struct ip6_hdr *); 663 break; 664 #endif 665 } 666 th = (struct tcphdr *)(mtod(m, caddr_t) + toff); 667 } 668 optlen = off - sizeof (struct tcphdr); 669 optp = mtod(m, caddr_t) + toff + sizeof (struct tcphdr); 670 /* 671 * Do quick retrieval of timestamp options ("options 672 * prediction?"). If timestamp is the only option and it's 673 * formatted as recommended in RFC 1323 appendix A, we 674 * quickly get the values now and not bother calling 675 * tcp_dooptions(), etc. 676 */ 677 if ((optlen == TCPOLEN_TSTAMP_APPA || 678 (optlen > TCPOLEN_TSTAMP_APPA && 679 optp[TCPOLEN_TSTAMP_APPA] == TCPOPT_EOL)) && 680 *(u_int32_t *)optp == htonl(TCPOPT_TSTAMP_HDR) && 681 (th->th_flags & TH_SYN) == 0) { 682 opti.ts_present = 1; 683 opti.ts_val = ntohl(*(u_int32_t *)(optp + 4)); 684 opti.ts_ecr = ntohl(*(u_int32_t *)(optp + 8)); 685 optp = NULL; /* we've parsed the options */ 686 } 687 } 688 tiflags = th->th_flags; 689 690 /* 691 * Convert TCP protocol specific fields to host format. 692 */ 693 NTOHL(th->th_seq); 694 NTOHL(th->th_ack); 695 NTOHS(th->th_win); 696 NTOHS(th->th_urp); 697 698 /* 699 * Locate pcb for segment. 700 */ 701 findpcb: 702 inp = NULL; 703 #ifdef INET6 704 in6p = NULL; 705 #endif 706 switch (af) { 707 case AF_INET: 708 inp = in_pcblookup_connect(&tcbtable, ip->ip_src, th->th_sport, 709 ip->ip_dst, th->th_dport); 710 if (inp == 0) { 711 ++tcpstat.tcps_pcbhashmiss; 712 inp = in_pcblookup_bind(&tcbtable, ip->ip_dst, th->th_dport); 713 } 714 #if defined(INET6) && !defined(TCP6) 715 if (inp == 0) { 716 struct in6_addr s, d; 717 718 /* mapped addr case */ 719 bzero(&s, sizeof(s)); 720 s.s6_addr16[5] = htons(0xffff); 721 bcopy(&ip->ip_src, &s.s6_addr32[3], sizeof(ip->ip_src)); 722 bzero(&d, sizeof(d)); 723 d.s6_addr16[5] = htons(0xffff); 724 bcopy(&ip->ip_dst, &d.s6_addr32[3], sizeof(ip->ip_dst)); 725 in6p = in6_pcblookup_connect(&tcb6, &s, th->th_sport, 726 &d, th->th_dport, 0); 727 if (in6p == 0) { 728 ++tcpstat.tcps_pcbhashmiss; 729 in6p = in6_pcblookup_bind(&tcb6, &d, 730 th->th_dport, 0); 731 } 732 } 733 #endif 734 #ifndef INET6 735 if (inp == 0) 736 #else 737 if (inp == 0 && in6p == 0) 738 #endif 739 { 740 ++tcpstat.tcps_noport; 741 if (tcp_log_refused && (tiflags & TH_SYN)) { 742 #ifndef INET6 743 char src[4*sizeof "123"]; 744 char dst[4*sizeof "123"]; 745 #else 746 char src[INET6_ADDRSTRLEN]; 747 char dst[INET6_ADDRSTRLEN]; 748 #endif 749 if (ip) { 750 strcpy(src, inet_ntoa(ip->ip_src)); 751 strcpy(dst, inet_ntoa(ip->ip_dst)); 752 } 753 #ifdef INET6 754 else if (ip6) { 755 strcpy(src, ip6_sprintf(&ip6->ip6_src)); 756 strcpy(dst, ip6_sprintf(&ip6->ip6_dst)); 757 } 758 #endif 759 else { 760 strcpy(src, "(unknown)"); 761 strcpy(dst, "(unknown)"); 762 } 763 log(LOG_INFO, 764 "Connection attempt to TCP %s:%d from %s:%d\n", 765 dst, ntohs(th->th_dport), 766 src, ntohs(th->th_sport)); 767 } 768 goto dropwithreset; 769 } 770 #ifdef IPSEC 771 if (inp && ipsec4_in_reject(m, inp)) { 772 ipsecstat.in_polvio++; 773 goto drop; 774 } 775 #ifdef INET6 776 else if (in6p && ipsec4_in_reject_so(m, in6p->in6p_socket)) { 777 ipsecstat.in_polvio++; 778 goto drop; 779 } 780 #endif 781 #endif /*IPSEC*/ 782 break; 783 #if defined(INET6) && !defined(TCP6) 784 case AF_INET6: 785 { 786 int faith; 787 788 #if defined(NFAITH) && NFAITH > 0 789 if (m->m_pkthdr.rcvif 790 && m->m_pkthdr.rcvif->if_type == IFT_FAITH) { 791 faith = 1; 792 } else 793 faith = 0; 794 #else 795 faith = 0; 796 #endif 797 in6p = in6_pcblookup_connect(&tcb6, &ip6->ip6_src, th->th_sport, 798 &ip6->ip6_dst, th->th_dport, faith); 799 if (in6p == NULL) { 800 ++tcpstat.tcps_pcbhashmiss; 801 in6p = in6_pcblookup_bind(&tcb6, &ip6->ip6_dst, 802 th->th_dport, faith); 803 } 804 if (in6p == NULL) { 805 ++tcpstat.tcps_noport; 806 goto dropwithreset; 807 } 808 #ifdef IPSEC 809 if (ipsec6_in_reject(m, in6p)) { 810 ipsec6stat.in_polvio++; 811 goto drop; 812 } 813 #endif /*IPSEC*/ 814 break; 815 } 816 #endif 817 } 818 819 /* 820 * If the state is CLOSED (i.e., TCB does not exist) then 821 * all data in the incoming segment is discarded. 822 * If the TCB exists but is in CLOSED state, it is embryonic, 823 * but should either do a listen or a connect soon. 824 */ 825 tp = NULL; 826 so = NULL; 827 if (inp) { 828 tp = intotcpcb(inp); 829 so = inp->inp_socket; 830 } 831 #ifdef INET6 832 else if (in6p) { 833 tp = in6totcpcb(in6p); 834 so = in6p->in6p_socket; 835 } 836 #endif 837 if (tp == 0) { 838 goto dropwithreset; 839 } 840 if (tp->t_state == TCPS_CLOSED) 841 goto drop; 842 843 /* Unscale the window into a 32-bit value. */ 844 if ((tiflags & TH_SYN) == 0) 845 tiwin = th->th_win << tp->snd_scale; 846 else 847 tiwin = th->th_win; 848 849 #ifdef INET6 850 /* save packet options if user wanted */ 851 if (in6p && (in6p->in6p_flags & IN6P_CONTROLOPTS)) { 852 if (in6p->in6p_options) { 853 m_freem(in6p->in6p_options); 854 in6p->in6p_options = 0; 855 } 856 ip6_savecontrol(in6p, &in6p->in6p_options, ip6, m); 857 } 858 #endif 859 860 if (so->so_options & (SO_DEBUG|SO_ACCEPTCONN)) { 861 union syn_cache_sa src; 862 union syn_cache_sa dst; 863 864 bzero(&src, sizeof(src)); 865 bzero(&dst, sizeof(dst)); 866 switch (af) { 867 case AF_INET: 868 src.sin.sin_len = sizeof(struct sockaddr_in); 869 src.sin.sin_family = AF_INET; 870 src.sin.sin_addr = ip->ip_src; 871 src.sin.sin_port = th->th_sport; 872 873 dst.sin.sin_len = sizeof(struct sockaddr_in); 874 dst.sin.sin_family = AF_INET; 875 dst.sin.sin_addr = ip->ip_dst; 876 dst.sin.sin_port = th->th_dport; 877 break; 878 #ifdef INET6 879 case AF_INET6: 880 src.sin6.sin6_len = sizeof(struct sockaddr_in6); 881 src.sin6.sin6_family = AF_INET6; 882 src.sin6.sin6_addr = ip6->ip6_src; 883 src.sin6.sin6_port = th->th_sport; 884 885 dst.sin6.sin6_len = sizeof(struct sockaddr_in6); 886 dst.sin6.sin6_family = AF_INET6; 887 dst.sin6.sin6_addr = ip6->ip6_dst; 888 dst.sin6.sin6_port = th->th_dport; 889 break; 890 #endif /* INET6 */ 891 default: 892 goto badsyn; /*sanity*/ 893 } 894 895 if (so->so_options & SO_DEBUG) { 896 ostate = tp->t_state; 897 tcp_saveti = m_copym(m, 0, iphlen, M_DONTWAIT); 898 if (M_TRAILINGSPACE(tcp_saveti) < sizeof(struct tcphdr)) { 899 m_freem(tcp_saveti); 900 tcp_saveti = NULL; 901 } else { 902 tcp_saveti->m_len += sizeof(struct tcphdr); 903 bcopy(th, mtod(tcp_saveti, caddr_t) + iphlen, 904 sizeof(struct tcphdr)); 905 } 906 if (tcp_saveti) { 907 /* 908 * need to recover version # field, which was 909 * overwritten on ip_cksum computation. 910 */ 911 struct ip *sip; 912 sip = mtod(tcp_saveti, struct ip *); 913 switch (af) { 914 case AF_INET: 915 sip->ip_v = 4; 916 break; 917 #ifdef INET6 918 case AF_INET6: 919 sip->ip_v = 6; 920 break; 921 #endif 922 } 923 } 924 } 925 if (so->so_options & SO_ACCEPTCONN) { 926 if ((tiflags & (TH_RST|TH_ACK|TH_SYN)) != TH_SYN) { 927 if (tiflags & TH_RST) { 928 syn_cache_reset(&src.sa, &dst.sa, th); 929 } else if ((tiflags & (TH_ACK|TH_SYN)) == 930 (TH_ACK|TH_SYN)) { 931 /* 932 * Received a SYN,ACK. This should 933 * never happen while we are in 934 * LISTEN. Send an RST. 935 */ 936 goto badsyn; 937 } else if (tiflags & TH_ACK) { 938 so = syn_cache_get(&src.sa, &dst.sa, 939 th, toff, tlen, so, m); 940 if (so == NULL) { 941 /* 942 * We don't have a SYN for 943 * this ACK; send an RST. 944 */ 945 goto badsyn; 946 } else if (so == 947 (struct socket *)(-1)) { 948 /* 949 * We were unable to create 950 * the connection. If the 951 * 3-way handshake was 952 * completed, and RST has 953 * been sent to the peer. 954 * Since the mbuf might be 955 * in use for the reply, 956 * do not free it. 957 */ 958 m = NULL; 959 } else { 960 /* 961 * We have created a 962 * full-blown connection. 963 */ 964 tp = NULL; 965 inp = NULL; 966 #ifdef INET6 967 in6p = NULL; 968 #endif 969 switch (so->so_proto->pr_domain->dom_family) { 970 case AF_INET: 971 inp = sotoinpcb(so); 972 tp = intotcpcb(inp); 973 break; 974 #ifdef INET6 975 case AF_INET6: 976 in6p = sotoin6pcb(so); 977 tp = in6totcpcb(in6p); 978 break; 979 #endif 980 } 981 if (tp == NULL) 982 goto badsyn; /*XXX*/ 983 tiwin <<= tp->snd_scale; 984 goto after_listen; 985 } 986 } else { 987 /* 988 * None of RST, SYN or ACK was set. 989 * This is an invalid packet for a 990 * TCB in LISTEN state. Send a RST. 991 */ 992 goto badsyn; 993 } 994 } else { 995 /* 996 * Received a SYN. 997 */ 998 999 /* 1000 * LISTEN socket received a SYN 1001 * from itself? This can't possibly 1002 * be valid; drop the packet. 1003 */ 1004 if (th->th_sport == th->th_dport) { 1005 int i; 1006 1007 switch (af) { 1008 case AF_INET: 1009 i = in_hosteq(ip->ip_src, ip->ip_dst); 1010 break; 1011 #ifdef INET6 1012 case AF_INET6: 1013 i = IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &ip6->ip6_dst); 1014 break; 1015 #endif 1016 default: 1017 i = 1; 1018 } 1019 if (i) { 1020 tcpstat.tcps_badsyn++; 1021 goto drop; 1022 } 1023 } 1024 1025 /* 1026 * SYN looks ok; create compressed TCP 1027 * state for it. 1028 */ 1029 if (so->so_qlen <= so->so_qlimit && 1030 syn_cache_add(&src.sa, &dst.sa, th, tlen, 1031 so, m, optp, optlen, &opti)) 1032 m = NULL; 1033 } 1034 goto drop; 1035 } 1036 } 1037 1038 after_listen: 1039 #ifdef DIAGNOSTIC 1040 /* 1041 * Should not happen now that all embryonic connections 1042 * are handled with compressed state. 1043 */ 1044 if (tp->t_state == TCPS_LISTEN) 1045 panic("tcp_input: TCPS_LISTEN"); 1046 #endif 1047 1048 /* 1049 * Segment received on connection. 1050 * Reset idle time and keep-alive timer. 1051 */ 1052 tp->t_idle = 0; 1053 if (TCPS_HAVEESTABLISHED(tp->t_state)) 1054 TCP_TIMER_ARM(tp, TCPT_KEEP, tcp_keepidle); 1055 1056 /* 1057 * Process options. 1058 */ 1059 if (optp) 1060 tcp_dooptions(tp, optp, optlen, th, &opti); 1061 1062 /* 1063 * Header prediction: check for the two common cases 1064 * of a uni-directional data xfer. If the packet has 1065 * no control flags, is in-sequence, the window didn't 1066 * change and we're not retransmitting, it's a 1067 * candidate. If the length is zero and the ack moved 1068 * forward, we're the sender side of the xfer. Just 1069 * free the data acked & wake any higher level process 1070 * that was blocked waiting for space. If the length 1071 * is non-zero and the ack didn't move, we're the 1072 * receiver side. If we're getting packets in-order 1073 * (the reassembly queue is empty), add the data to 1074 * the socket buffer and note that we need a delayed ack. 1075 */ 1076 if (tp->t_state == TCPS_ESTABLISHED && 1077 (tiflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK && 1078 (!opti.ts_present || TSTMP_GEQ(opti.ts_val, tp->ts_recent)) && 1079 th->th_seq == tp->rcv_nxt && 1080 tiwin && tiwin == tp->snd_wnd && 1081 tp->snd_nxt == tp->snd_max) { 1082 1083 /* 1084 * If last ACK falls within this segment's sequence numbers, 1085 * record the timestamp. 1086 */ 1087 if (opti.ts_present && 1088 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 1089 SEQ_LT(tp->last_ack_sent, th->th_seq + tlen)) { 1090 tp->ts_recent_age = tcp_now; 1091 tp->ts_recent = opti.ts_val; 1092 } 1093 1094 if (tlen == 0) { 1095 if (SEQ_GT(th->th_ack, tp->snd_una) && 1096 SEQ_LEQ(th->th_ack, tp->snd_max) && 1097 tp->snd_cwnd >= tp->snd_wnd && 1098 tp->t_dupacks < tcprexmtthresh) { 1099 /* 1100 * this is a pure ack for outstanding data. 1101 */ 1102 ++tcpstat.tcps_predack; 1103 if (opti.ts_present && opti.ts_ecr) 1104 tcp_xmit_timer(tp, 1105 tcp_now - opti.ts_ecr + 1); 1106 else if (tp->t_rtt && 1107 SEQ_GT(th->th_ack, tp->t_rtseq)) 1108 tcp_xmit_timer(tp, tp->t_rtt); 1109 acked = th->th_ack - tp->snd_una; 1110 tcpstat.tcps_rcvackpack++; 1111 tcpstat.tcps_rcvackbyte += acked; 1112 sbdrop(&so->so_snd, acked); 1113 /* 1114 * We want snd_recover to track snd_una to 1115 * avoid sequence wraparound problems for 1116 * very large transfers. 1117 */ 1118 tp->snd_una = tp->snd_recover = th->th_ack; 1119 m_freem(m); 1120 1121 /* 1122 * If all outstanding data are acked, stop 1123 * retransmit timer, otherwise restart timer 1124 * using current (possibly backed-off) value. 1125 * If process is waiting for space, 1126 * wakeup/selwakeup/signal. If data 1127 * are ready to send, let tcp_output 1128 * decide between more output or persist. 1129 */ 1130 if (tp->snd_una == tp->snd_max) 1131 TCP_TIMER_DISARM(tp, TCPT_REXMT); 1132 else if (TCP_TIMER_ISARMED(tp, 1133 TCPT_PERSIST) == 0) 1134 TCP_TIMER_ARM(tp, TCPT_REXMT, 1135 tp->t_rxtcur); 1136 1137 sowwakeup(so); 1138 if (so->so_snd.sb_cc) 1139 (void) tcp_output(tp); 1140 if (tcp_saveti) 1141 m_freem(tcp_saveti); 1142 return; 1143 } 1144 } else if (th->th_ack == tp->snd_una && 1145 tp->segq.lh_first == NULL && 1146 tlen <= sbspace(&so->so_rcv)) { 1147 /* 1148 * this is a pure, in-sequence data packet 1149 * with nothing on the reassembly queue and 1150 * we have enough buffer space to take it. 1151 */ 1152 ++tcpstat.tcps_preddat; 1153 tp->rcv_nxt += tlen; 1154 tcpstat.tcps_rcvpack++; 1155 tcpstat.tcps_rcvbyte += tlen; 1156 /* 1157 * Drop TCP, IP headers and TCP options then add data 1158 * to socket buffer. 1159 */ 1160 m->m_data += toff + off; 1161 m->m_len -= (toff + off); 1162 sbappend(&so->so_rcv, m); 1163 sorwakeup(so); 1164 TCP_SETUP_ACK(tp, th); 1165 if (tp->t_flags & TF_ACKNOW) 1166 (void) tcp_output(tp); 1167 if (tcp_saveti) 1168 m_freem(tcp_saveti); 1169 return; 1170 } 1171 } 1172 1173 /* 1174 * Drop TCP, IP headers and TCP options. 1175 */ 1176 hdroptlen = toff + off; 1177 m->m_data += hdroptlen; 1178 m->m_len -= hdroptlen; 1179 1180 /* 1181 * Calculate amount of space in receive window, 1182 * and then do TCP input processing. 1183 * Receive window is amount of space in rcv queue, 1184 * but not less than advertised window. 1185 */ 1186 { int win; 1187 1188 win = sbspace(&so->so_rcv); 1189 if (win < 0) 1190 win = 0; 1191 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 1192 } 1193 1194 switch (tp->t_state) { 1195 1196 /* 1197 * If the state is SYN_SENT: 1198 * if seg contains an ACK, but not for our SYN, drop the input. 1199 * if seg contains a RST, then drop the connection. 1200 * if seg does not contain SYN, then drop it. 1201 * Otherwise this is an acceptable SYN segment 1202 * initialize tp->rcv_nxt and tp->irs 1203 * if seg contains ack then advance tp->snd_una 1204 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 1205 * arrange for segment to be acked (eventually) 1206 * continue processing rest of data/controls, beginning with URG 1207 */ 1208 case TCPS_SYN_SENT: 1209 if ((tiflags & TH_ACK) && 1210 (SEQ_LEQ(th->th_ack, tp->iss) || 1211 SEQ_GT(th->th_ack, tp->snd_max))) 1212 goto dropwithreset; 1213 if (tiflags & TH_RST) { 1214 if (tiflags & TH_ACK) 1215 tp = tcp_drop(tp, ECONNREFUSED); 1216 goto drop; 1217 } 1218 if ((tiflags & TH_SYN) == 0) 1219 goto drop; 1220 if (tiflags & TH_ACK) { 1221 tp->snd_una = tp->snd_recover = th->th_ack; 1222 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 1223 tp->snd_nxt = tp->snd_una; 1224 } 1225 TCP_TIMER_DISARM(tp, TCPT_REXMT); 1226 tp->irs = th->th_seq; 1227 tcp_rcvseqinit(tp); 1228 tp->t_flags |= TF_ACKNOW; 1229 tcp_mss_from_peer(tp, opti.maxseg); 1230 1231 /* 1232 * Initialize the initial congestion window. If we 1233 * had to retransmit the SYN, we must initialize cwnd 1234 * to 1 segment (i.e. the Loss Window). 1235 */ 1236 if (tp->t_flags & TF_SYN_REXMT) 1237 tp->snd_cwnd = tp->t_peermss; 1238 else 1239 tp->snd_cwnd = TCP_INITIAL_WINDOW(tcp_init_win, 1240 tp->t_peermss); 1241 1242 tcp_rmx_rtt(tp); 1243 if (tiflags & TH_ACK && SEQ_GT(tp->snd_una, tp->iss)) { 1244 tcpstat.tcps_connects++; 1245 soisconnected(so); 1246 tcp_established(tp); 1247 /* Do window scaling on this connection? */ 1248 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 1249 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 1250 tp->snd_scale = tp->requested_s_scale; 1251 tp->rcv_scale = tp->request_r_scale; 1252 } 1253 TCP_REASS_LOCK(tp); 1254 (void) tcp_reass(tp, NULL, (struct mbuf *)0, &tlen); 1255 TCP_REASS_UNLOCK(tp); 1256 /* 1257 * if we didn't have to retransmit the SYN, 1258 * use its rtt as our initial srtt & rtt var. 1259 */ 1260 if (tp->t_rtt) 1261 tcp_xmit_timer(tp, tp->t_rtt); 1262 } else 1263 tp->t_state = TCPS_SYN_RECEIVED; 1264 1265 /* 1266 * Advance th->th_seq to correspond to first data byte. 1267 * If data, trim to stay within window, 1268 * dropping FIN if necessary. 1269 */ 1270 th->th_seq++; 1271 if (tlen > tp->rcv_wnd) { 1272 todrop = tlen - tp->rcv_wnd; 1273 m_adj(m, -todrop); 1274 tlen = tp->rcv_wnd; 1275 tiflags &= ~TH_FIN; 1276 tcpstat.tcps_rcvpackafterwin++; 1277 tcpstat.tcps_rcvbyteafterwin += todrop; 1278 } 1279 tp->snd_wl1 = th->th_seq - 1; 1280 tp->rcv_up = th->th_seq; 1281 goto step6; 1282 1283 /* 1284 * If the state is SYN_RECEIVED: 1285 * If seg contains an ACK, but not for our SYN, drop the input 1286 * and generate an RST. See page 36, rfc793 1287 */ 1288 case TCPS_SYN_RECEIVED: 1289 if ((tiflags & TH_ACK) && 1290 (SEQ_LEQ(th->th_ack, tp->iss) || 1291 SEQ_GT(th->th_ack, tp->snd_max))) 1292 goto dropwithreset; 1293 break; 1294 } 1295 1296 /* 1297 * States other than LISTEN or SYN_SENT. 1298 * First check timestamp, if present. 1299 * Then check that at least some bytes of segment are within 1300 * receive window. If segment begins before rcv_nxt, 1301 * drop leading data (and SYN); if nothing left, just ack. 1302 * 1303 * RFC 1323 PAWS: If we have a timestamp reply on this segment 1304 * and it's less than ts_recent, drop it. 1305 */ 1306 if (opti.ts_present && (tiflags & TH_RST) == 0 && tp->ts_recent && 1307 TSTMP_LT(opti.ts_val, tp->ts_recent)) { 1308 1309 /* Check to see if ts_recent is over 24 days old. */ 1310 if ((int)(tcp_now - tp->ts_recent_age) > TCP_PAWS_IDLE) { 1311 /* 1312 * Invalidate ts_recent. If this segment updates 1313 * ts_recent, the age will be reset later and ts_recent 1314 * will get a valid value. If it does not, setting 1315 * ts_recent to zero will at least satisfy the 1316 * requirement that zero be placed in the timestamp 1317 * echo reply when ts_recent isn't valid. The 1318 * age isn't reset until we get a valid ts_recent 1319 * because we don't want out-of-order segments to be 1320 * dropped when ts_recent is old. 1321 */ 1322 tp->ts_recent = 0; 1323 } else { 1324 tcpstat.tcps_rcvduppack++; 1325 tcpstat.tcps_rcvdupbyte += tlen; 1326 tcpstat.tcps_pawsdrop++; 1327 goto dropafterack; 1328 } 1329 } 1330 1331 todrop = tp->rcv_nxt - th->th_seq; 1332 if (todrop > 0) { 1333 if (tiflags & TH_SYN) { 1334 tiflags &= ~TH_SYN; 1335 th->th_seq++; 1336 if (th->th_urp > 1) 1337 th->th_urp--; 1338 else { 1339 tiflags &= ~TH_URG; 1340 th->th_urp = 0; 1341 } 1342 todrop--; 1343 } 1344 if (todrop > tlen || 1345 (todrop == tlen && (tiflags & TH_FIN) == 0)) { 1346 /* 1347 * Any valid FIN must be to the left of the window. 1348 * At this point the FIN must be a duplicate or 1349 * out of sequence; drop it. 1350 */ 1351 tiflags &= ~TH_FIN; 1352 /* 1353 * Send an ACK to resynchronize and drop any data. 1354 * But keep on processing for RST or ACK. 1355 */ 1356 tp->t_flags |= TF_ACKNOW; 1357 todrop = tlen; 1358 tcpstat.tcps_rcvdupbyte += todrop; 1359 tcpstat.tcps_rcvduppack++; 1360 } else { 1361 tcpstat.tcps_rcvpartduppack++; 1362 tcpstat.tcps_rcvpartdupbyte += todrop; 1363 } 1364 m_adj(m, todrop); 1365 th->th_seq += todrop; 1366 tlen -= todrop; 1367 if (th->th_urp > todrop) 1368 th->th_urp -= todrop; 1369 else { 1370 tiflags &= ~TH_URG; 1371 th->th_urp = 0; 1372 } 1373 } 1374 1375 /* 1376 * If new data are received on a connection after the 1377 * user processes are gone, then RST the other end. 1378 */ 1379 if ((so->so_state & SS_NOFDREF) && 1380 tp->t_state > TCPS_CLOSE_WAIT && tlen) { 1381 tp = tcp_close(tp); 1382 tcpstat.tcps_rcvafterclose++; 1383 goto dropwithreset; 1384 } 1385 1386 /* 1387 * If segment ends after window, drop trailing data 1388 * (and PUSH and FIN); if nothing left, just ACK. 1389 */ 1390 todrop = (th->th_seq + tlen) - (tp->rcv_nxt+tp->rcv_wnd); 1391 if (todrop > 0) { 1392 tcpstat.tcps_rcvpackafterwin++; 1393 if (todrop >= tlen) { 1394 tcpstat.tcps_rcvbyteafterwin += tlen; 1395 /* 1396 * If a new connection request is received 1397 * while in TIME_WAIT, drop the old connection 1398 * and start over if the sequence numbers 1399 * are above the previous ones. 1400 */ 1401 if (tiflags & TH_SYN && 1402 tp->t_state == TCPS_TIME_WAIT && 1403 SEQ_GT(th->th_seq, tp->rcv_nxt)) { 1404 iss = tcp_new_iss(tp, sizeof(struct tcpcb), 1405 tp->snd_nxt); 1406 tp = tcp_close(tp); 1407 /* 1408 * We have already advanced the mbuf 1409 * pointers past the IP+TCP headers and 1410 * options. Restore those pointers before 1411 * attempting to use the TCP header again. 1412 */ 1413 m->m_data -= hdroptlen; 1414 m->m_len += hdroptlen; 1415 hdroptlen = 0; 1416 goto findpcb; 1417 } 1418 /* 1419 * If window is closed can only take segments at 1420 * window edge, and have to drop data and PUSH from 1421 * incoming segments. Continue processing, but 1422 * remember to ack. Otherwise, drop segment 1423 * and ack. 1424 */ 1425 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 1426 tp->t_flags |= TF_ACKNOW; 1427 tcpstat.tcps_rcvwinprobe++; 1428 } else 1429 goto dropafterack; 1430 } else 1431 tcpstat.tcps_rcvbyteafterwin += todrop; 1432 m_adj(m, -todrop); 1433 tlen -= todrop; 1434 tiflags &= ~(TH_PUSH|TH_FIN); 1435 } 1436 1437 /* 1438 * If last ACK falls within this segment's sequence numbers, 1439 * and the timestamp is newer, record it. 1440 */ 1441 if (opti.ts_present && TSTMP_GEQ(opti.ts_val, tp->ts_recent) && 1442 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 1443 SEQ_LT(tp->last_ack_sent, th->th_seq + tlen + 1444 ((tiflags & (TH_SYN|TH_FIN)) != 0))) { 1445 tp->ts_recent_age = tcp_now; 1446 tp->ts_recent = opti.ts_val; 1447 } 1448 1449 /* 1450 * If the RST bit is set examine the state: 1451 * SYN_RECEIVED STATE: 1452 * If passive open, return to LISTEN state. 1453 * If active open, inform user that connection was refused. 1454 * ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES: 1455 * Inform user that connection was reset, and close tcb. 1456 * CLOSING, LAST_ACK, TIME_WAIT STATES 1457 * Close the tcb. 1458 */ 1459 if (tiflags&TH_RST) switch (tp->t_state) { 1460 1461 case TCPS_SYN_RECEIVED: 1462 so->so_error = ECONNREFUSED; 1463 goto close; 1464 1465 case TCPS_ESTABLISHED: 1466 case TCPS_FIN_WAIT_1: 1467 case TCPS_FIN_WAIT_2: 1468 case TCPS_CLOSE_WAIT: 1469 so->so_error = ECONNRESET; 1470 close: 1471 tp->t_state = TCPS_CLOSED; 1472 tcpstat.tcps_drops++; 1473 tp = tcp_close(tp); 1474 goto drop; 1475 1476 case TCPS_CLOSING: 1477 case TCPS_LAST_ACK: 1478 case TCPS_TIME_WAIT: 1479 tp = tcp_close(tp); 1480 goto drop; 1481 } 1482 1483 /* 1484 * If a SYN is in the window, then this is an 1485 * error and we send an RST and drop the connection. 1486 */ 1487 if (tiflags & TH_SYN) { 1488 tp = tcp_drop(tp, ECONNRESET); 1489 goto dropwithreset; 1490 } 1491 1492 /* 1493 * If the ACK bit is off we drop the segment and return. 1494 */ 1495 if ((tiflags & TH_ACK) == 0) { 1496 if (tp->t_flags & TF_ACKNOW) 1497 goto dropafterack; 1498 else 1499 goto drop; 1500 } 1501 1502 /* 1503 * Ack processing. 1504 */ 1505 switch (tp->t_state) { 1506 1507 /* 1508 * In SYN_RECEIVED state if the ack ACKs our SYN then enter 1509 * ESTABLISHED state and continue processing, otherwise 1510 * send an RST. 1511 */ 1512 case TCPS_SYN_RECEIVED: 1513 if (SEQ_GT(tp->snd_una, th->th_ack) || 1514 SEQ_GT(th->th_ack, tp->snd_max)) 1515 goto dropwithreset; 1516 tcpstat.tcps_connects++; 1517 soisconnected(so); 1518 tcp_established(tp); 1519 /* Do window scaling? */ 1520 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 1521 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 1522 tp->snd_scale = tp->requested_s_scale; 1523 tp->rcv_scale = tp->request_r_scale; 1524 } 1525 TCP_REASS_LOCK(tp); 1526 (void) tcp_reass(tp, NULL, (struct mbuf *)0, &tlen); 1527 TCP_REASS_UNLOCK(tp); 1528 tp->snd_wl1 = th->th_seq - 1; 1529 /* fall into ... */ 1530 1531 /* 1532 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 1533 * ACKs. If the ack is in the range 1534 * tp->snd_una < th->th_ack <= tp->snd_max 1535 * then advance tp->snd_una to th->th_ack and drop 1536 * data from the retransmission queue. If this ACK reflects 1537 * more up to date window information we update our window information. 1538 */ 1539 case TCPS_ESTABLISHED: 1540 case TCPS_FIN_WAIT_1: 1541 case TCPS_FIN_WAIT_2: 1542 case TCPS_CLOSE_WAIT: 1543 case TCPS_CLOSING: 1544 case TCPS_LAST_ACK: 1545 case TCPS_TIME_WAIT: 1546 1547 if (SEQ_LEQ(th->th_ack, tp->snd_una)) { 1548 if (tlen == 0 && tiwin == tp->snd_wnd) { 1549 tcpstat.tcps_rcvdupack++; 1550 /* 1551 * If we have outstanding data (other than 1552 * a window probe), this is a completely 1553 * duplicate ack (ie, window info didn't 1554 * change), the ack is the biggest we've 1555 * seen and we've seen exactly our rexmt 1556 * threshhold of them, assume a packet 1557 * has been dropped and retransmit it. 1558 * Kludge snd_nxt & the congestion 1559 * window so we send only this one 1560 * packet. 1561 * 1562 * We know we're losing at the current 1563 * window size so do congestion avoidance 1564 * (set ssthresh to half the current window 1565 * and pull our congestion window back to 1566 * the new ssthresh). 1567 * 1568 * Dup acks mean that packets have left the 1569 * network (they're now cached at the receiver) 1570 * so bump cwnd by the amount in the receiver 1571 * to keep a constant cwnd packets in the 1572 * network. 1573 */ 1574 if (TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 || 1575 th->th_ack != tp->snd_una) 1576 tp->t_dupacks = 0; 1577 else if (++tp->t_dupacks == tcprexmtthresh) { 1578 tcp_seq onxt = tp->snd_nxt; 1579 u_int win = 1580 min(tp->snd_wnd, tp->snd_cwnd) / 1581 2 / tp->t_segsz; 1582 if (SEQ_LT(th->th_ack, 1583 tp->snd_recover)) { 1584 /* 1585 * False fast retransmit after 1586 * timeout. Do not cut window. 1587 */ 1588 tp->snd_cwnd += tp->t_segsz; 1589 tp->t_dupacks = 0; 1590 (void) tcp_output(tp); 1591 goto drop; 1592 } 1593 1594 if (win < 2) 1595 win = 2; 1596 tp->snd_ssthresh = win * tp->t_segsz; 1597 tp->snd_recover = tp->snd_max; 1598 TCP_TIMER_DISARM(tp, TCPT_REXMT); 1599 tp->t_rtt = 0; 1600 tp->snd_nxt = th->th_ack; 1601 tp->snd_cwnd = tp->t_segsz; 1602 (void) tcp_output(tp); 1603 tp->snd_cwnd = tp->snd_ssthresh + 1604 tp->t_segsz * tp->t_dupacks; 1605 if (SEQ_GT(onxt, tp->snd_nxt)) 1606 tp->snd_nxt = onxt; 1607 goto drop; 1608 } else if (tp->t_dupacks > tcprexmtthresh) { 1609 tp->snd_cwnd += tp->t_segsz; 1610 (void) tcp_output(tp); 1611 goto drop; 1612 } 1613 } else 1614 tp->t_dupacks = 0; 1615 break; 1616 } 1617 /* 1618 * If the congestion window was inflated to account 1619 * for the other side's cached packets, retract it. 1620 */ 1621 if (!tcp_do_newreno) { 1622 if (tp->t_dupacks >= tcprexmtthresh && 1623 tp->snd_cwnd > tp->snd_ssthresh) 1624 tp->snd_cwnd = tp->snd_ssthresh; 1625 tp->t_dupacks = 0; 1626 } else if (tp->t_dupacks >= tcprexmtthresh 1627 && !tcp_newreno(tp, th)) { 1628 tp->snd_cwnd = tp->snd_ssthresh; 1629 /* 1630 * Window inflation should have left us with approx. 1631 * snd_ssthresh outstanding data. But in case we 1632 * would be inclined to send a burst, better to do 1633 * it via the slow start mechanism. 1634 */ 1635 if (SEQ_SUB(tp->snd_max, th->th_ack) < tp->snd_ssthresh) 1636 tp->snd_cwnd = SEQ_SUB(tp->snd_max, th->th_ack) 1637 + tp->t_segsz; 1638 tp->t_dupacks = 0; 1639 } 1640 if (SEQ_GT(th->th_ack, tp->snd_max)) { 1641 tcpstat.tcps_rcvacktoomuch++; 1642 goto dropafterack; 1643 } 1644 acked = th->th_ack - tp->snd_una; 1645 tcpstat.tcps_rcvackpack++; 1646 tcpstat.tcps_rcvackbyte += acked; 1647 1648 /* 1649 * If we have a timestamp reply, update smoothed 1650 * round trip time. If no timestamp is present but 1651 * transmit timer is running and timed sequence 1652 * number was acked, update smoothed round trip time. 1653 * Since we now have an rtt measurement, cancel the 1654 * timer backoff (cf., Phil Karn's retransmit alg.). 1655 * Recompute the initial retransmit timer. 1656 */ 1657 if (opti.ts_present && opti.ts_ecr) 1658 tcp_xmit_timer(tp, tcp_now - opti.ts_ecr + 1); 1659 else if (tp->t_rtt && SEQ_GT(th->th_ack, tp->t_rtseq)) 1660 tcp_xmit_timer(tp,tp->t_rtt); 1661 1662 /* 1663 * If all outstanding data is acked, stop retransmit 1664 * timer and remember to restart (more output or persist). 1665 * If there is more data to be acked, restart retransmit 1666 * timer, using current (possibly backed-off) value. 1667 */ 1668 if (th->th_ack == tp->snd_max) { 1669 TCP_TIMER_DISARM(tp, TCPT_REXMT); 1670 needoutput = 1; 1671 } else if (TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) 1672 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 1673 /* 1674 * When new data is acked, open the congestion window. 1675 * If the window gives us less than ssthresh packets 1676 * in flight, open exponentially (segsz per packet). 1677 * Otherwise open linearly: segsz per window 1678 * (segsz^2 / cwnd per packet), plus a constant 1679 * fraction of a packet (segsz/8) to help larger windows 1680 * open quickly enough. 1681 */ 1682 { 1683 register u_int cw = tp->snd_cwnd; 1684 register u_int incr = tp->t_segsz; 1685 1686 if (cw > tp->snd_ssthresh) 1687 incr = incr * incr / cw; 1688 if (!tcp_do_newreno || SEQ_GEQ(th->th_ack, tp->snd_recover)) 1689 tp->snd_cwnd = min(cw + incr,TCP_MAXWIN<<tp->snd_scale); 1690 } 1691 if (acked > so->so_snd.sb_cc) { 1692 tp->snd_wnd -= so->so_snd.sb_cc; 1693 sbdrop(&so->so_snd, (int)so->so_snd.sb_cc); 1694 ourfinisacked = 1; 1695 } else { 1696 sbdrop(&so->so_snd, acked); 1697 tp->snd_wnd -= acked; 1698 ourfinisacked = 0; 1699 } 1700 sowwakeup(so); 1701 /* 1702 * We want snd_recover to track snd_una to 1703 * avoid sequence wraparound problems for 1704 * very large transfers. 1705 */ 1706 tp->snd_una = tp->snd_recover = th->th_ack; 1707 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 1708 tp->snd_nxt = tp->snd_una; 1709 1710 switch (tp->t_state) { 1711 1712 /* 1713 * In FIN_WAIT_1 STATE in addition to the processing 1714 * for the ESTABLISHED state if our FIN is now acknowledged 1715 * then enter FIN_WAIT_2. 1716 */ 1717 case TCPS_FIN_WAIT_1: 1718 if (ourfinisacked) { 1719 /* 1720 * If we can't receive any more 1721 * data, then closing user can proceed. 1722 * Starting the timer is contrary to the 1723 * specification, but if we don't get a FIN 1724 * we'll hang forever. 1725 */ 1726 if (so->so_state & SS_CANTRCVMORE) { 1727 soisdisconnected(so); 1728 if (tcp_maxidle > 0) 1729 TCP_TIMER_ARM(tp, TCPT_2MSL, 1730 tcp_maxidle); 1731 } 1732 tp->t_state = TCPS_FIN_WAIT_2; 1733 } 1734 break; 1735 1736 /* 1737 * In CLOSING STATE in addition to the processing for 1738 * the ESTABLISHED state if the ACK acknowledges our FIN 1739 * then enter the TIME-WAIT state, otherwise ignore 1740 * the segment. 1741 */ 1742 case TCPS_CLOSING: 1743 if (ourfinisacked) { 1744 tp->t_state = TCPS_TIME_WAIT; 1745 tcp_canceltimers(tp); 1746 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 1747 soisdisconnected(so); 1748 } 1749 break; 1750 1751 /* 1752 * In LAST_ACK, we may still be waiting for data to drain 1753 * and/or to be acked, as well as for the ack of our FIN. 1754 * If our FIN is now acknowledged, delete the TCB, 1755 * enter the closed state and return. 1756 */ 1757 case TCPS_LAST_ACK: 1758 if (ourfinisacked) { 1759 tp = tcp_close(tp); 1760 goto drop; 1761 } 1762 break; 1763 1764 /* 1765 * In TIME_WAIT state the only thing that should arrive 1766 * is a retransmission of the remote FIN. Acknowledge 1767 * it and restart the finack timer. 1768 */ 1769 case TCPS_TIME_WAIT: 1770 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 1771 goto dropafterack; 1772 } 1773 } 1774 1775 step6: 1776 /* 1777 * Update window information. 1778 * Don't look at window if no ACK: TAC's send garbage on first SYN. 1779 */ 1780 if ((tiflags & TH_ACK) && (SEQ_LT(tp->snd_wl1, th->th_seq) || 1781 (tp->snd_wl1 == th->th_seq && SEQ_LT(tp->snd_wl2, th->th_ack)) || 1782 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))) { 1783 /* keep track of pure window updates */ 1784 if (tlen == 0 && 1785 tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) 1786 tcpstat.tcps_rcvwinupd++; 1787 tp->snd_wnd = tiwin; 1788 tp->snd_wl1 = th->th_seq; 1789 tp->snd_wl2 = th->th_ack; 1790 if (tp->snd_wnd > tp->max_sndwnd) 1791 tp->max_sndwnd = tp->snd_wnd; 1792 needoutput = 1; 1793 } 1794 1795 /* 1796 * Process segments with URG. 1797 */ 1798 if ((tiflags & TH_URG) && th->th_urp && 1799 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 1800 /* 1801 * This is a kludge, but if we receive and accept 1802 * random urgent pointers, we'll crash in 1803 * soreceive. It's hard to imagine someone 1804 * actually wanting to send this much urgent data. 1805 */ 1806 if (th->th_urp + so->so_rcv.sb_cc > sb_max) { 1807 th->th_urp = 0; /* XXX */ 1808 tiflags &= ~TH_URG; /* XXX */ 1809 goto dodata; /* XXX */ 1810 } 1811 /* 1812 * If this segment advances the known urgent pointer, 1813 * then mark the data stream. This should not happen 1814 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 1815 * a FIN has been received from the remote side. 1816 * In these states we ignore the URG. 1817 * 1818 * According to RFC961 (Assigned Protocols), 1819 * the urgent pointer points to the last octet 1820 * of urgent data. We continue, however, 1821 * to consider it to indicate the first octet 1822 * of data past the urgent section as the original 1823 * spec states (in one of two places). 1824 */ 1825 if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) { 1826 tp->rcv_up = th->th_seq + th->th_urp; 1827 so->so_oobmark = so->so_rcv.sb_cc + 1828 (tp->rcv_up - tp->rcv_nxt) - 1; 1829 if (so->so_oobmark == 0) 1830 so->so_state |= SS_RCVATMARK; 1831 sohasoutofband(so); 1832 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); 1833 } 1834 /* 1835 * Remove out of band data so doesn't get presented to user. 1836 * This can happen independent of advancing the URG pointer, 1837 * but if two URG's are pending at once, some out-of-band 1838 * data may creep in... ick. 1839 */ 1840 if (th->th_urp <= (u_int16_t) tlen 1841 #ifdef SO_OOBINLINE 1842 && (so->so_options & SO_OOBINLINE) == 0 1843 #endif 1844 ) 1845 tcp_pulloutofband(so, th, m); 1846 } else 1847 /* 1848 * If no out of band data is expected, 1849 * pull receive urgent pointer along 1850 * with the receive window. 1851 */ 1852 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) 1853 tp->rcv_up = tp->rcv_nxt; 1854 dodata: /* XXX */ 1855 1856 /* 1857 * Process the segment text, merging it into the TCP sequencing queue, 1858 * and arranging for acknowledgment of receipt if necessary. 1859 * This process logically involves adjusting tp->rcv_wnd as data 1860 * is presented to the user (this happens in tcp_usrreq.c, 1861 * case PRU_RCVD). If a FIN has already been received on this 1862 * connection then we just ignore the text. 1863 */ 1864 if ((tlen || (tiflags & TH_FIN)) && 1865 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 1866 /* 1867 * Insert segment ti into reassembly queue of tcp with 1868 * control block tp. Return TH_FIN if reassembly now includes 1869 * a segment with FIN. The macro form does the common case 1870 * inline (segment is the next to be received on an 1871 * established connection, and the queue is empty), 1872 * avoiding linkage into and removal from the queue and 1873 * repetition of various conversions. 1874 * Set DELACK for segments received in order, but ack 1875 * immediately when segments are out of order 1876 * (so fast retransmit can work). 1877 */ 1878 /* NOTE: this was TCP_REASS() macro, but used only once */ 1879 TCP_REASS_LOCK(tp); 1880 if (th->th_seq == tp->rcv_nxt && 1881 tp->segq.lh_first == NULL && 1882 tp->t_state == TCPS_ESTABLISHED) { 1883 TCP_SETUP_ACK(tp, th); 1884 tp->rcv_nxt += tlen; 1885 tiflags = th->th_flags & TH_FIN; 1886 tcpstat.tcps_rcvpack++;\ 1887 tcpstat.tcps_rcvbyte += tlen;\ 1888 sbappend(&(so)->so_rcv, m); 1889 sorwakeup(so); 1890 } else { 1891 tiflags = tcp_reass(tp, th, m, &tlen); 1892 tp->t_flags |= TF_ACKNOW; 1893 } 1894 TCP_REASS_UNLOCK(tp); 1895 1896 /* 1897 * Note the amount of data that peer has sent into 1898 * our window, in order to estimate the sender's 1899 * buffer size. 1900 */ 1901 len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); 1902 } else { 1903 m_freem(m); 1904 m = NULL; 1905 tiflags &= ~TH_FIN; 1906 } 1907 1908 /* 1909 * If FIN is received ACK the FIN and let the user know 1910 * that the connection is closing. Ignore a FIN received before 1911 * the connection is fully established. 1912 */ 1913 if ((tiflags & TH_FIN) && TCPS_HAVEESTABLISHED(tp->t_state)) { 1914 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 1915 socantrcvmore(so); 1916 tp->t_flags |= TF_ACKNOW; 1917 tp->rcv_nxt++; 1918 } 1919 switch (tp->t_state) { 1920 1921 /* 1922 * In ESTABLISHED STATE enter the CLOSE_WAIT state. 1923 */ 1924 case TCPS_ESTABLISHED: 1925 tp->t_state = TCPS_CLOSE_WAIT; 1926 break; 1927 1928 /* 1929 * If still in FIN_WAIT_1 STATE FIN has not been acked so 1930 * enter the CLOSING state. 1931 */ 1932 case TCPS_FIN_WAIT_1: 1933 tp->t_state = TCPS_CLOSING; 1934 break; 1935 1936 /* 1937 * In FIN_WAIT_2 state enter the TIME_WAIT state, 1938 * starting the time-wait timer, turning off the other 1939 * standard timers. 1940 */ 1941 case TCPS_FIN_WAIT_2: 1942 tp->t_state = TCPS_TIME_WAIT; 1943 tcp_canceltimers(tp); 1944 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 1945 soisdisconnected(so); 1946 break; 1947 1948 /* 1949 * In TIME_WAIT state restart the 2 MSL time_wait timer. 1950 */ 1951 case TCPS_TIME_WAIT: 1952 TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL); 1953 break; 1954 } 1955 } 1956 if (so->so_options & SO_DEBUG) { 1957 tcp_trace(TA_INPUT, ostate, tp, tcp_saveti, 0); 1958 } 1959 1960 /* 1961 * Return any desired output. 1962 */ 1963 if (needoutput || (tp->t_flags & TF_ACKNOW)) 1964 (void) tcp_output(tp); 1965 if (tcp_saveti) 1966 m_freem(tcp_saveti); 1967 return; 1968 1969 badsyn: 1970 /* 1971 * Received a bad SYN. Increment counters and dropwithreset. 1972 */ 1973 tcpstat.tcps_badsyn++; 1974 tp = NULL; 1975 goto dropwithreset; 1976 1977 dropafterack: 1978 /* 1979 * Generate an ACK dropping incoming segment if it occupies 1980 * sequence space, where the ACK reflects our state. 1981 */ 1982 if (tiflags & TH_RST) 1983 goto drop; 1984 m_freem(m); 1985 tp->t_flags |= TF_ACKNOW; 1986 (void) tcp_output(tp); 1987 if (tcp_saveti) 1988 m_freem(tcp_saveti); 1989 return; 1990 1991 dropwithreset: 1992 /* 1993 * Generate a RST, dropping incoming segment. 1994 * Make ACK acceptable to originator of segment. 1995 * Don't bother to respond if destination was broadcast/multicast. 1996 */ 1997 if ((tiflags & TH_RST) || m->m_flags & (M_BCAST|M_MCAST)) 1998 goto drop; 1999 if (ip && IN_MULTICAST(ip->ip_dst.s_addr)) 2000 goto drop; 2001 #ifdef INET6 2002 if (m->m_flags & M_ANYCAST6) 2003 goto drop; 2004 else if (ip6 && IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) 2005 goto drop; 2006 #endif 2007 /* recover the header if dropped. */ 2008 m->m_data -= hdroptlen; 2009 m->m_len += hdroptlen; 2010 { 2011 /* 2012 * need to recover version # field, which was overwritten on 2013 * ip_cksum computation. 2014 */ 2015 struct ip *sip; 2016 sip = mtod(m, struct ip *); 2017 switch (af) { 2018 case AF_INET: 2019 sip->ip_v = 4; 2020 break; 2021 #ifdef INET6 2022 case AF_INET6: 2023 sip->ip_v = 6; 2024 break; 2025 #endif 2026 } 2027 } 2028 if (tiflags & TH_ACK) 2029 (void)tcp_respond(tp, m, m, th, (tcp_seq)0, th->th_ack, TH_RST); 2030 else { 2031 if (tiflags & TH_SYN) 2032 tlen++; 2033 (void)tcp_respond(tp, m, m, th, th->th_seq + tlen, (tcp_seq)0, 2034 TH_RST|TH_ACK); 2035 } 2036 if (tcp_saveti) 2037 m_freem(tcp_saveti); 2038 return; 2039 2040 drop: 2041 /* 2042 * Drop space held by incoming segment and return. 2043 */ 2044 if (tp) { 2045 if (tp->t_inpcb) 2046 so = tp->t_inpcb->inp_socket; 2047 #ifdef INET6 2048 else if (tp->t_in6pcb) 2049 so = tp->t_in6pcb->in6p_socket; 2050 #endif 2051 else 2052 so = NULL; 2053 if (so && (so->so_options & SO_DEBUG) != 0) 2054 tcp_trace(TA_DROP, ostate, tp, tcp_saveti, 0); 2055 } 2056 if (tcp_saveti) 2057 m_freem(tcp_saveti); 2058 m_freem(m); 2059 return; 2060 } 2061 2062 void 2063 tcp_dooptions(tp, cp, cnt, th, oi) 2064 struct tcpcb *tp; 2065 u_char *cp; 2066 int cnt; 2067 struct tcphdr *th; 2068 struct tcp_opt_info *oi; 2069 { 2070 u_int16_t mss; 2071 int opt, optlen; 2072 2073 for (; cnt > 0; cnt -= optlen, cp += optlen) { 2074 opt = cp[0]; 2075 if (opt == TCPOPT_EOL) 2076 break; 2077 if (opt == TCPOPT_NOP) 2078 optlen = 1; 2079 else { 2080 optlen = cp[1]; 2081 if (optlen <= 0) 2082 break; 2083 } 2084 switch (opt) { 2085 2086 default: 2087 continue; 2088 2089 case TCPOPT_MAXSEG: 2090 if (optlen != TCPOLEN_MAXSEG) 2091 continue; 2092 if (!(th->th_flags & TH_SYN)) 2093 continue; 2094 bcopy(cp + 2, &mss, sizeof(mss)); 2095 oi->maxseg = ntohs(mss); 2096 break; 2097 2098 case TCPOPT_WINDOW: 2099 if (optlen != TCPOLEN_WINDOW) 2100 continue; 2101 if (!(th->th_flags & TH_SYN)) 2102 continue; 2103 tp->t_flags |= TF_RCVD_SCALE; 2104 tp->requested_s_scale = cp[2]; 2105 if (tp->requested_s_scale > TCP_MAX_WINSHIFT) { 2106 #if 0 /*XXX*/ 2107 char *p; 2108 2109 if (ip) 2110 p = ntohl(ip->ip_src); 2111 #ifdef INET6 2112 else if (ip6) 2113 p = ip6_sprintf(&ip6->ip6_src); 2114 #endif 2115 else 2116 p = "(unknown)"; 2117 log(LOG_ERR, "TCP: invalid wscale %d from %s, " 2118 "assuming %d\n", 2119 tp->requested_s_scale, p, 2120 TCP_MAX_WINSHIFT); 2121 #else 2122 log(LOG_ERR, "TCP: invalid wscale %d, " 2123 "assuming %d\n", 2124 tp->requested_s_scale, 2125 TCP_MAX_WINSHIFT); 2126 #endif 2127 tp->requested_s_scale = TCP_MAX_WINSHIFT; 2128 } 2129 break; 2130 2131 case TCPOPT_TIMESTAMP: 2132 if (optlen != TCPOLEN_TIMESTAMP) 2133 continue; 2134 oi->ts_present = 1; 2135 bcopy(cp + 2, &oi->ts_val, sizeof(oi->ts_val)); 2136 NTOHL(oi->ts_val); 2137 bcopy(cp + 6, &oi->ts_ecr, sizeof(oi->ts_ecr)); 2138 NTOHL(oi->ts_ecr); 2139 2140 /* 2141 * A timestamp received in a SYN makes 2142 * it ok to send timestamp requests and replies. 2143 */ 2144 if (th->th_flags & TH_SYN) { 2145 tp->t_flags |= TF_RCVD_TSTMP; 2146 tp->ts_recent = oi->ts_val; 2147 tp->ts_recent_age = tcp_now; 2148 } 2149 break; 2150 case TCPOPT_SACK_PERMITTED: 2151 if (optlen != TCPOLEN_SACK_PERMITTED) 2152 continue; 2153 if (!(th->th_flags & TH_SYN)) 2154 continue; 2155 tp->t_flags &= ~TF_CANT_TXSACK; 2156 break; 2157 2158 case TCPOPT_SACK: 2159 if (tp->t_flags & TF_IGNR_RXSACK) 2160 continue; 2161 if (optlen % 8 != 2 || optlen < 10) 2162 continue; 2163 cp += 2; 2164 optlen -= 2; 2165 for (; optlen > 0; cp -= 8, optlen -= 8) { 2166 tcp_seq lwe, rwe; 2167 bcopy((char *)cp, (char *) &lwe, sizeof(lwe)); 2168 NTOHL(lwe); 2169 bcopy((char *)cp, (char *) &rwe, sizeof(rwe)); 2170 NTOHL(rwe); 2171 /* tcp_mark_sacked(tp, lwe, rwe); */ 2172 } 2173 break; 2174 } 2175 } 2176 } 2177 2178 /* 2179 * Pull out of band byte out of a segment so 2180 * it doesn't appear in the user's data queue. 2181 * It is still reflected in the segment length for 2182 * sequencing purposes. 2183 */ 2184 void 2185 tcp_pulloutofband(so, th, m) 2186 struct socket *so; 2187 struct tcphdr *th; 2188 register struct mbuf *m; 2189 { 2190 int cnt = th->th_urp - 1; 2191 2192 while (cnt >= 0) { 2193 if (m->m_len > cnt) { 2194 char *cp = mtod(m, caddr_t) + cnt; 2195 struct tcpcb *tp = sototcpcb(so); 2196 2197 tp->t_iobc = *cp; 2198 tp->t_oobflags |= TCPOOB_HAVEDATA; 2199 bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); 2200 m->m_len--; 2201 return; 2202 } 2203 cnt -= m->m_len; 2204 m = m->m_next; 2205 if (m == 0) 2206 break; 2207 } 2208 panic("tcp_pulloutofband"); 2209 } 2210 2211 /* 2212 * Collect new round-trip time estimate 2213 * and update averages and current timeout. 2214 */ 2215 void 2216 tcp_xmit_timer(tp, rtt) 2217 register struct tcpcb *tp; 2218 short rtt; 2219 { 2220 register short delta; 2221 short rttmin; 2222 2223 tcpstat.tcps_rttupdated++; 2224 --rtt; 2225 if (tp->t_srtt != 0) { 2226 /* 2227 * srtt is stored as fixed point with 3 bits after the 2228 * binary point (i.e., scaled by 8). The following magic 2229 * is equivalent to the smoothing algorithm in rfc793 with 2230 * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed 2231 * point). Adjust rtt to origin 0. 2232 */ 2233 delta = (rtt << 2) - (tp->t_srtt >> TCP_RTT_SHIFT); 2234 if ((tp->t_srtt += delta) <= 0) 2235 tp->t_srtt = 1 << 2; 2236 /* 2237 * We accumulate a smoothed rtt variance (actually, a 2238 * smoothed mean difference), then set the retransmit 2239 * timer to smoothed rtt + 4 times the smoothed variance. 2240 * rttvar is stored as fixed point with 2 bits after the 2241 * binary point (scaled by 4). The following is 2242 * equivalent to rfc793 smoothing with an alpha of .75 2243 * (rttvar = rttvar*3/4 + |delta| / 4). This replaces 2244 * rfc793's wired-in beta. 2245 */ 2246 if (delta < 0) 2247 delta = -delta; 2248 delta -= (tp->t_rttvar >> TCP_RTTVAR_SHIFT); 2249 if ((tp->t_rttvar += delta) <= 0) 2250 tp->t_rttvar = 1 << 2; 2251 } else { 2252 /* 2253 * No rtt measurement yet - use the unsmoothed rtt. 2254 * Set the variance to half the rtt (so our first 2255 * retransmit happens at 3*rtt). 2256 */ 2257 tp->t_srtt = rtt << (TCP_RTT_SHIFT + 2); 2258 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT + 2 - 1); 2259 } 2260 tp->t_rtt = 0; 2261 tp->t_rxtshift = 0; 2262 2263 /* 2264 * the retransmit should happen at rtt + 4 * rttvar. 2265 * Because of the way we do the smoothing, srtt and rttvar 2266 * will each average +1/2 tick of bias. When we compute 2267 * the retransmit timer, we want 1/2 tick of rounding and 2268 * 1 extra tick because of +-1/2 tick uncertainty in the 2269 * firing of the timer. The bias will give us exactly the 2270 * 1.5 tick we need. But, because the bias is 2271 * statistical, we have to test that we don't drop below 2272 * the minimum feasible timer (which is 2 ticks). 2273 */ 2274 if (tp->t_rttmin > rtt + 2) 2275 rttmin = tp->t_rttmin; 2276 else 2277 rttmin = rtt + 2; 2278 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), rttmin, TCPTV_REXMTMAX); 2279 2280 /* 2281 * We received an ack for a packet that wasn't retransmitted; 2282 * it is probably safe to discard any error indications we've 2283 * received recently. This isn't quite right, but close enough 2284 * for now (a route might have failed after we sent a segment, 2285 * and the return path might not be symmetrical). 2286 */ 2287 tp->t_softerror = 0; 2288 } 2289 2290 /* 2291 * Checks for partial ack. If partial ack arrives, force the retransmission 2292 * of the next unacknowledged segment, do not clear tp->t_dupacks, and return 2293 * 1. By setting snd_nxt to th_ack, this forces retransmission timer to 2294 * be started again. If the ack advances at least to tp->snd_recover, return 0. 2295 */ 2296 int 2297 tcp_newreno(tp, th) 2298 struct tcpcb *tp; 2299 struct tcphdr *th; 2300 { 2301 tcp_seq onxt = tp->snd_nxt; 2302 u_long ocwnd = tp->snd_cwnd; 2303 2304 if (SEQ_LT(th->th_ack, tp->snd_recover)) { 2305 /* 2306 * snd_una has not yet been updated and the socket's send 2307 * buffer has not yet drained off the ACK'd data, so we 2308 * have to leave snd_una as it was to get the correct data 2309 * offset in tcp_output(). 2310 */ 2311 TCP_TIMER_DISARM(tp, TCPT_REXMT); 2312 tp->t_rtt = 0; 2313 tp->snd_nxt = th->th_ack; 2314 /* 2315 * Set snd_cwnd to one segment beyond ACK'd offset. snd_una 2316 * is not yet updated when we're called. 2317 */ 2318 tp->snd_cwnd = tp->t_segsz + (th->th_ack - tp->snd_una); 2319 (void) tcp_output(tp); 2320 tp->snd_cwnd = ocwnd; 2321 if (SEQ_GT(onxt, tp->snd_nxt)) 2322 tp->snd_nxt = onxt; 2323 /* 2324 * Partial window deflation. Relies on fact that tp->snd_una 2325 * not updated yet. 2326 */ 2327 tp->snd_cwnd -= (th->th_ack - tp->snd_una - tp->t_segsz); 2328 return 1; 2329 } 2330 return 0; 2331 } 2332 2333 2334 /* 2335 * TCP compressed state engine. Currently used to hold compressed 2336 * state for SYN_RECEIVED. 2337 */ 2338 2339 u_long syn_cache_count; 2340 u_int32_t syn_hash1, syn_hash2; 2341 2342 #define SYN_HASH(sa, sp, dp) \ 2343 ((((sa)->s_addr^syn_hash1)*(((((u_int32_t)(dp))<<16) + \ 2344 ((u_int32_t)(sp)))^syn_hash2))) 2345 #ifndef INET6 2346 #define SYN_HASHALL(hash, src, dst) \ 2347 do { \ 2348 hash = SYN_HASH(&((struct sockaddr_in *)(src))->sin_addr, \ 2349 ((struct sockaddr_in *)(src))->sin_port, \ 2350 ((struct sockaddr_in *)(dst))->sin_port); \ 2351 } while (0) 2352 #else 2353 #define SYN_HASH6(sa, sp, dp) \ 2354 ((((sa)->s6_addr32[0] ^ (sa)->s6_addr32[3] ^ syn_hash1) * \ 2355 (((((u_int32_t)(dp))<<16) + ((u_int32_t)(sp)))^syn_hash2)) \ 2356 & 0x7fffffff) 2357 2358 #define SYN_HASHALL(hash, src, dst) \ 2359 do { \ 2360 switch ((src)->sa_family) { \ 2361 case AF_INET: \ 2362 hash = SYN_HASH(&((struct sockaddr_in *)(src))->sin_addr, \ 2363 ((struct sockaddr_in *)(src))->sin_port, \ 2364 ((struct sockaddr_in *)(dst))->sin_port); \ 2365 break; \ 2366 case AF_INET6: \ 2367 hash = SYN_HASH6(&((struct sockaddr_in6 *)(src))->sin6_addr, \ 2368 ((struct sockaddr_in6 *)(src))->sin6_port, \ 2369 ((struct sockaddr_in6 *)(dst))->sin6_port); \ 2370 break; \ 2371 default: \ 2372 hash = 0; \ 2373 } \ 2374 } while (0) 2375 #endif /* INET6 */ 2376 2377 #define SYN_CACHE_RM(sc) \ 2378 do { \ 2379 LIST_REMOVE((sc), sc_bucketq); \ 2380 tcp_syn_cache[(sc)->sc_bucketidx].sch_length--; \ 2381 TAILQ_REMOVE(&tcp_syn_cache_timeq[(sc)->sc_rxtshift], (sc), sc_timeq); \ 2382 syn_cache_count--; \ 2383 } while (0) 2384 2385 #define SYN_CACHE_PUT(sc) \ 2386 do { \ 2387 if ((sc)->sc_ipopts) \ 2388 (void) m_free((sc)->sc_ipopts); \ 2389 if ((sc)->sc_route4.ro_rt != NULL) \ 2390 RTFREE((sc)->sc_route4.ro_rt); \ 2391 pool_put(&syn_cache_pool, (sc)); \ 2392 } while (0) 2393 2394 struct pool syn_cache_pool; 2395 2396 /* 2397 * We don't estimate RTT with SYNs, so each packet starts with the default 2398 * RTT and each timer queue has a fixed timeout value. This allows us to 2399 * optimize the timer queues somewhat. 2400 */ 2401 #define SYN_CACHE_TIMER_ARM(sc) \ 2402 do { \ 2403 TCPT_RANGESET((sc)->sc_rxtcur, \ 2404 TCPTV_SRTTDFLT * tcp_backoff[(sc)->sc_rxtshift], TCPTV_MIN, \ 2405 TCPTV_REXMTMAX); \ 2406 PRT_SLOW_ARM((sc)->sc_rexmt, (sc)->sc_rxtcur); \ 2407 } while (0) 2408 2409 TAILQ_HEAD(, syn_cache) tcp_syn_cache_timeq[TCP_MAXRXTSHIFT + 1]; 2410 2411 void 2412 syn_cache_init() 2413 { 2414 int i; 2415 2416 /* Initialize the hash buckets. */ 2417 for (i = 0; i < tcp_syn_cache_size; i++) 2418 LIST_INIT(&tcp_syn_cache[i].sch_bucket); 2419 2420 /* Initialize the timer queues. */ 2421 for (i = 0; i <= TCP_MAXRXTSHIFT; i++) 2422 TAILQ_INIT(&tcp_syn_cache_timeq[i]); 2423 2424 /* Initialize the syn cache pool. */ 2425 pool_init(&syn_cache_pool, sizeof(struct syn_cache), 0, 0, 0, 2426 "synpl", 0, NULL, NULL, M_PCB); 2427 } 2428 2429 void 2430 syn_cache_insert(sc) 2431 struct syn_cache *sc; 2432 { 2433 struct syn_cache_head *scp; 2434 struct syn_cache *sc2; 2435 int s, i; 2436 2437 /* 2438 * If there are no entries in the hash table, reinitialize 2439 * the hash secrets. 2440 */ 2441 if (syn_cache_count == 0) { 2442 struct timeval tv; 2443 microtime(&tv); 2444 syn_hash1 = random() ^ (u_long)≻ 2445 syn_hash2 = random() ^ tv.tv_usec; 2446 } 2447 2448 SYN_HASHALL(sc->sc_hash, &sc->sc_src.sa, &sc->sc_dst.sa); 2449 sc->sc_bucketidx = sc->sc_hash % tcp_syn_cache_size; 2450 scp = &tcp_syn_cache[sc->sc_bucketidx]; 2451 2452 /* 2453 * Make sure that we don't overflow the per-bucket 2454 * limit or the total cache size limit. 2455 */ 2456 s = splsoftnet(); 2457 if (scp->sch_length >= tcp_syn_bucket_limit) { 2458 tcpstat.tcps_sc_bucketoverflow++; 2459 /* 2460 * The bucket is full. Toss the oldest element in the 2461 * bucket. This will be the entry with our bucket 2462 * index closest to the front of the timer queue with 2463 * the largest timeout value. 2464 * 2465 * Note: This timer queue traversal may be expensive, so 2466 * we hope that this doesn't happen very often. It is 2467 * much more likely that we'll overflow the entire 2468 * cache, which is much easier to handle; see below. 2469 */ 2470 for (i = TCP_MAXRXTSHIFT; i >= 0; i--) { 2471 for (sc2 = TAILQ_FIRST(&tcp_syn_cache_timeq[i]); 2472 sc2 != NULL; 2473 sc2 = TAILQ_NEXT(sc2, sc_timeq)) { 2474 if (sc2->sc_bucketidx == sc->sc_bucketidx) { 2475 SYN_CACHE_RM(sc2); 2476 SYN_CACHE_PUT(sc2); 2477 goto insert; /* 2 level break */ 2478 } 2479 } 2480 } 2481 #ifdef DIAGNOSTIC 2482 /* 2483 * This should never happen; we should always find an 2484 * entry in our bucket. 2485 */ 2486 panic("syn_cache_insert: bucketoverflow: impossible"); 2487 #endif 2488 } else if (syn_cache_count >= tcp_syn_cache_limit) { 2489 tcpstat.tcps_sc_overflowed++; 2490 /* 2491 * The cache is full. Toss the oldest entry in the 2492 * entire cache. This is the front entry in the 2493 * first non-empty timer queue with the largest 2494 * timeout value. 2495 */ 2496 for (i = TCP_MAXRXTSHIFT; i >= 0; i--) { 2497 sc2 = TAILQ_FIRST(&tcp_syn_cache_timeq[i]); 2498 if (sc2 == NULL) 2499 continue; 2500 SYN_CACHE_RM(sc2); 2501 SYN_CACHE_PUT(sc2); 2502 goto insert; /* symmetry with above */ 2503 } 2504 #ifdef DIAGNOSTIC 2505 /* 2506 * This should never happen; we should always find an 2507 * entry in the cache. 2508 */ 2509 panic("syn_cache_insert: cache overflow: impossible"); 2510 #endif 2511 } 2512 2513 insert: 2514 /* 2515 * Initialize the entry's timer. 2516 */ 2517 sc->sc_rxttot = 0; 2518 sc->sc_rxtshift = 0; 2519 SYN_CACHE_TIMER_ARM(sc); 2520 TAILQ_INSERT_TAIL(&tcp_syn_cache_timeq[sc->sc_rxtshift], sc, sc_timeq); 2521 2522 /* Put it into the bucket. */ 2523 LIST_INSERT_HEAD(&scp->sch_bucket, sc, sc_bucketq); 2524 scp->sch_length++; 2525 syn_cache_count++; 2526 2527 tcpstat.tcps_sc_added++; 2528 splx(s); 2529 } 2530 2531 /* 2532 * Walk the timer queues, looking for SYN,ACKs that need to be retransmitted. 2533 * If we have retransmitted an entry the maximum number of times, expire 2534 * that entry. 2535 */ 2536 void 2537 syn_cache_timer() 2538 { 2539 struct syn_cache *sc, *nsc; 2540 int i, s; 2541 2542 s = splsoftnet(); 2543 2544 /* 2545 * First, get all the entries that need to be retransmitted, or 2546 * must be expired due to exceeding the initial keepalive time. 2547 */ 2548 for (i = 0; i < TCP_MAXRXTSHIFT; i++) { 2549 for (sc = TAILQ_FIRST(&tcp_syn_cache_timeq[i]); 2550 sc != NULL && PRT_SLOW_ISEXPIRED(sc->sc_rexmt); 2551 sc = nsc) { 2552 nsc = TAILQ_NEXT(sc, sc_timeq); 2553 2554 /* 2555 * Compute the total amount of time this entry has 2556 * been on a queue. If this entry has been on longer 2557 * than the keep alive timer would allow, expire it. 2558 */ 2559 sc->sc_rxttot += sc->sc_rxtcur; 2560 if (sc->sc_rxttot >= TCPTV_KEEP_INIT) { 2561 tcpstat.tcps_sc_timed_out++; 2562 SYN_CACHE_RM(sc); 2563 SYN_CACHE_PUT(sc); 2564 continue; 2565 } 2566 2567 tcpstat.tcps_sc_retransmitted++; 2568 (void) syn_cache_respond(sc, NULL); 2569 2570 /* Advance this entry onto the next timer queue. */ 2571 TAILQ_REMOVE(&tcp_syn_cache_timeq[i], sc, sc_timeq); 2572 sc->sc_rxtshift = i + 1; 2573 SYN_CACHE_TIMER_ARM(sc); 2574 TAILQ_INSERT_TAIL(&tcp_syn_cache_timeq[sc->sc_rxtshift], 2575 sc, sc_timeq); 2576 } 2577 } 2578 2579 /* 2580 * Now get all the entries that are expired due to too many 2581 * retransmissions. 2582 */ 2583 for (sc = TAILQ_FIRST(&tcp_syn_cache_timeq[TCP_MAXRXTSHIFT]); 2584 sc != NULL && PRT_SLOW_ISEXPIRED(sc->sc_rexmt); 2585 sc = nsc) { 2586 nsc = TAILQ_NEXT(sc, sc_timeq); 2587 tcpstat.tcps_sc_timed_out++; 2588 SYN_CACHE_RM(sc); 2589 SYN_CACHE_PUT(sc); 2590 } 2591 splx(s); 2592 } 2593 2594 /* 2595 * Find an entry in the syn cache. 2596 */ 2597 struct syn_cache * 2598 syn_cache_lookup(src, dst, headp) 2599 struct sockaddr *src; 2600 struct sockaddr *dst; 2601 struct syn_cache_head **headp; 2602 { 2603 struct syn_cache *sc; 2604 struct syn_cache_head *scp; 2605 u_int32_t hash; 2606 int s; 2607 2608 SYN_HASHALL(hash, src, dst); 2609 2610 scp = &tcp_syn_cache[hash % tcp_syn_cache_size]; 2611 *headp = scp; 2612 s = splsoftnet(); 2613 for (sc = LIST_FIRST(&scp->sch_bucket); sc != NULL; 2614 sc = LIST_NEXT(sc, sc_bucketq)) { 2615 if (sc->sc_hash != hash) 2616 continue; 2617 if (!bcmp(&sc->sc_src, src, src->sa_len) && 2618 !bcmp(&sc->sc_dst, dst, dst->sa_len)) { 2619 splx(s); 2620 return (sc); 2621 } 2622 } 2623 splx(s); 2624 return (NULL); 2625 } 2626 2627 /* 2628 * This function gets called when we receive an ACK for a 2629 * socket in the LISTEN state. We look up the connection 2630 * in the syn cache, and if its there, we pull it out of 2631 * the cache and turn it into a full-blown connection in 2632 * the SYN-RECEIVED state. 2633 * 2634 * The return values may not be immediately obvious, and their effects 2635 * can be subtle, so here they are: 2636 * 2637 * NULL SYN was not found in cache; caller should drop the 2638 * packet and send an RST. 2639 * 2640 * -1 We were unable to create the new connection, and are 2641 * aborting it. An ACK,RST is being sent to the peer 2642 * (unless we got screwey sequence numbners; see below), 2643 * because the 3-way handshake has been completed. Caller 2644 * should not free the mbuf, since we may be using it. If 2645 * we are not, we will free it. 2646 * 2647 * Otherwise, the return value is a pointer to the new socket 2648 * associated with the connection. 2649 */ 2650 struct socket * 2651 syn_cache_get(src, dst, th, hlen, tlen, so, m) 2652 struct sockaddr *src; 2653 struct sockaddr *dst; 2654 struct tcphdr *th; 2655 unsigned int hlen, tlen; 2656 struct socket *so; 2657 struct mbuf *m; 2658 { 2659 struct syn_cache *sc; 2660 struct syn_cache_head *scp; 2661 register struct inpcb *inp = NULL; 2662 #ifdef INET6 2663 register struct in6pcb *in6p = NULL; 2664 #endif 2665 register struct tcpcb *tp = 0; 2666 struct mbuf *am; 2667 int s; 2668 struct socket *oso; 2669 2670 s = splsoftnet(); 2671 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 2672 splx(s); 2673 return (NULL); 2674 } 2675 2676 /* 2677 * Verify the sequence and ack numbers. Try getting the correct 2678 * response again. 2679 */ 2680 if ((th->th_ack != sc->sc_iss + 1) || 2681 SEQ_LEQ(th->th_seq, sc->sc_irs) || 2682 SEQ_GT(th->th_seq, sc->sc_irs + 1 + sc->sc_win)) { 2683 (void) syn_cache_respond(sc, m); 2684 splx(s); 2685 return ((struct socket *)(-1)); 2686 } 2687 2688 /* Remove this cache entry */ 2689 SYN_CACHE_RM(sc); 2690 splx(s); 2691 2692 /* 2693 * Ok, create the full blown connection, and set things up 2694 * as they would have been set up if we had created the 2695 * connection when the SYN arrived. If we can't create 2696 * the connection, abort it. 2697 */ 2698 /* 2699 * inp still has the OLD in_pcb stuff, set the 2700 * v6-related flags on the new guy, too. This is 2701 * done particularly for the case where an AF_INET6 2702 * socket is bound only to a port, and a v4 connection 2703 * comes in on that port. 2704 * we also copy the flowinfo from the original pcb 2705 * to the new one. 2706 */ 2707 { 2708 struct inpcb *parentinpcb; 2709 2710 parentinpcb = (struct inpcb *)so->so_pcb; 2711 2712 oso = so; 2713 so = sonewconn(so, SS_ISCONNECTED); 2714 if (so == NULL) 2715 goto resetandabort; 2716 2717 switch (so->so_proto->pr_domain->dom_family) { 2718 case AF_INET: 2719 inp = sotoinpcb(so); 2720 break; 2721 #ifdef INET6 2722 case AF_INET6: 2723 in6p = sotoin6pcb(so); 2724 #if 0 /*def INET6*/ 2725 inp->inp_flags |= (parentinpcb->inp_flags & 2726 (INP_IPV6 | INP_IPV6_UNDEC | INP_IPV6_MAPPED)); 2727 if ((inp->inp_flags & INP_IPV6) && 2728 !(inp->inp_flags & INP_IPV6_MAPPED)) { 2729 inp->inp_ipv6.ip6_hlim = parentinpcb->inp_ipv6.ip6_hlim; 2730 inp->inp_ipv6.ip6_vfc = parentinpcb->inp_ipv6.ip6_vfc; 2731 } 2732 #endif 2733 break; 2734 #endif 2735 } 2736 } 2737 switch (src->sa_family) { 2738 case AF_INET: 2739 if (inp) { 2740 inp->inp_laddr = ((struct sockaddr_in *)dst)->sin_addr; 2741 inp->inp_lport = ((struct sockaddr_in *)dst)->sin_port; 2742 inp->inp_options = ip_srcroute(); 2743 in_pcbstate(inp, INP_BOUND); 2744 if (inp->inp_options == NULL) { 2745 inp->inp_options = sc->sc_ipopts; 2746 sc->sc_ipopts = NULL; 2747 } 2748 } 2749 #ifdef INET6 2750 else if (in6p) { 2751 /* IPv4 packet to AF_INET6 socket */ 2752 bzero(&in6p->in6p_laddr, sizeof(in6p->in6p_laddr)); 2753 in6p->in6p_laddr.s6_addr16[5] = htons(0xffff); 2754 bcopy(&((struct sockaddr_in *)dst)->sin_addr, 2755 &in6p->in6p_laddr.s6_addr32[3], 2756 sizeof(((struct sockaddr_in *)dst)->sin_addr)); 2757 in6p->in6p_lport = ((struct sockaddr_in *)dst)->sin_port; 2758 in6totcpcb(in6p)->t_family = AF_INET; 2759 } 2760 #endif 2761 break; 2762 #ifdef INET6 2763 case AF_INET6: 2764 if (in6p) { 2765 in6p->in6p_laddr = ((struct sockaddr_in6 *)dst)->sin6_addr; 2766 in6p->in6p_lport = ((struct sockaddr_in6 *)dst)->sin6_port; 2767 #if 0 2768 in6p->in6p_flowinfo = ip6->ip6_flow & IPV6_FLOWINFO_MASK; 2769 /*inp->inp_options = ip6_srcroute();*/ /* soon. */ 2770 #endif 2771 } 2772 break; 2773 #endif 2774 } 2775 #ifdef INET6 2776 if (in6p && in6totcpcb(in6p)->t_family == AF_INET6 && sotoinpcb(oso)) { 2777 struct in6pcb *oin6p = sotoin6pcb(oso); 2778 /* inherit socket options from the listening socket */ 2779 in6p->in6p_flags |= (oin6p->in6p_flags & IN6P_CONTROLOPTS); 2780 if (in6p->in6p_flags & IN6P_CONTROLOPTS) { 2781 m_freem(in6p->in6p_options); 2782 in6p->in6p_options = 0; 2783 } 2784 ip6_savecontrol(in6p, &in6p->in6p_options, 2785 mtod(m, struct ip6_hdr *), m); 2786 } 2787 #endif 2788 2789 #ifdef IPSEC 2790 { 2791 struct secpolicy *sp; 2792 if (inp) { 2793 sp = ipsec_copy_policy(sotoinpcb(oso)->inp_sp); 2794 if (sp) { 2795 key_freesp(inp->inp_sp); 2796 inp->inp_sp = sp; 2797 } else 2798 printf("tcp_input: could not copy policy\n"); 2799 } 2800 #ifdef INET6 2801 else if (in6p) { 2802 sp = ipsec_copy_policy(sotoin6pcb(oso)->in6p_sp); 2803 if (sp) { 2804 key_freesp(in6p->in6p_sp); 2805 in6p->in6p_sp = sp; 2806 } else 2807 printf("tcp_input: could not copy policy\n"); 2808 } 2809 #endif 2810 } 2811 #endif 2812 2813 /* 2814 * Give the new socket our cached route reference. 2815 */ 2816 if (inp) 2817 inp->inp_route = sc->sc_route4; /* struct assignment */ 2818 #ifdef INET6 2819 else 2820 in6p->in6p_route = sc->sc_route6; 2821 #endif 2822 sc->sc_route4.ro_rt = NULL; 2823 2824 am = m_get(M_DONTWAIT, MT_SONAME); /* XXX */ 2825 if (am == NULL) 2826 goto resetandabort; 2827 am->m_len = src->sa_len; 2828 bcopy(src, mtod(am, caddr_t), src->sa_len); 2829 if (inp) { 2830 if (in_pcbconnect(inp, am)) { 2831 (void) m_free(am); 2832 goto resetandabort; 2833 } 2834 } 2835 #ifdef INET6 2836 else if (in6p) { 2837 if (src->sa_family == AF_INET) { 2838 /* IPv4 packet to AF_INET6 socket */ 2839 struct sockaddr_in6 *sin6; 2840 sin6 = mtod(am, struct sockaddr_in6 *); 2841 am->m_len = sizeof(*sin6); 2842 bzero(sin6, sizeof(*sin6)); 2843 sin6->sin6_family = AF_INET6; 2844 sin6->sin6_len = sizeof(*sin6); 2845 sin6->sin6_port = ((struct sockaddr_in *)src)->sin_port; 2846 sin6->sin6_addr.s6_addr16[5] = htons(0xffff); 2847 bcopy(&((struct sockaddr_in *)src)->sin_addr, 2848 &sin6->sin6_addr.s6_addr32[3], 2849 sizeof(sin6->sin6_addr.s6_addr32[3])); 2850 } 2851 if (in6_pcbconnect(in6p, am)) { 2852 (void) m_free(am); 2853 goto resetandabort; 2854 } 2855 } 2856 #endif 2857 else { 2858 (void) m_free(am); 2859 goto resetandabort; 2860 } 2861 (void) m_free(am); 2862 2863 if (inp) 2864 tp = intotcpcb(inp); 2865 #ifdef INET6 2866 else if (in6p) 2867 tp = in6totcpcb(in6p); 2868 #endif 2869 else 2870 tp = NULL; 2871 if (sc->sc_request_r_scale != 15) { 2872 tp->requested_s_scale = sc->sc_requested_s_scale; 2873 tp->request_r_scale = sc->sc_request_r_scale; 2874 tp->snd_scale = sc->sc_requested_s_scale; 2875 tp->rcv_scale = sc->sc_request_r_scale; 2876 tp->t_flags |= TF_RCVD_SCALE; 2877 } 2878 if (sc->sc_flags & SCF_TIMESTAMP) 2879 tp->t_flags |= TF_RCVD_TSTMP; 2880 2881 tp->t_template = tcp_template(tp); 2882 if (tp->t_template == 0) { 2883 tp = tcp_drop(tp, ENOBUFS); /* destroys socket */ 2884 so = NULL; 2885 m_freem(m); 2886 goto abort; 2887 } 2888 2889 tp->iss = sc->sc_iss; 2890 tp->irs = sc->sc_irs; 2891 tcp_sendseqinit(tp); 2892 tcp_rcvseqinit(tp); 2893 tp->t_state = TCPS_SYN_RECEIVED; 2894 TCP_TIMER_ARM(tp, TCPT_KEEP, TCPTV_KEEP_INIT); 2895 tcpstat.tcps_accepts++; 2896 2897 /* Initialize tp->t_ourmss before we deal with the peer's! */ 2898 tp->t_ourmss = sc->sc_ourmaxseg; 2899 tcp_mss_from_peer(tp, sc->sc_peermaxseg); 2900 2901 /* 2902 * Initialize the initial congestion window. If we 2903 * had to retransmit the SYN,ACK, we must initialize cwnd 2904 * to 1 segment (i.e. the Loss Window). 2905 */ 2906 if (sc->sc_rxtshift) 2907 tp->snd_cwnd = tp->t_peermss; 2908 else 2909 tp->snd_cwnd = TCP_INITIAL_WINDOW(tcp_init_win, tp->t_peermss); 2910 2911 tcp_rmx_rtt(tp); 2912 tp->snd_wl1 = sc->sc_irs; 2913 tp->rcv_up = sc->sc_irs + 1; 2914 2915 /* 2916 * This is what whould have happened in tcp_ouput() when 2917 * the SYN,ACK was sent. 2918 */ 2919 tp->snd_up = tp->snd_una; 2920 tp->snd_max = tp->snd_nxt = tp->iss+1; 2921 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 2922 if (sc->sc_win > 0 && SEQ_GT(tp->rcv_nxt + sc->sc_win, tp->rcv_adv)) 2923 tp->rcv_adv = tp->rcv_nxt + sc->sc_win; 2924 tp->last_ack_sent = tp->rcv_nxt; 2925 2926 tcpstat.tcps_sc_completed++; 2927 SYN_CACHE_PUT(sc); 2928 return (so); 2929 2930 resetandabort: 2931 (void) tcp_respond(NULL, m, m, th, 2932 th->th_seq + tlen, (tcp_seq)0, TH_RST|TH_ACK); 2933 abort: 2934 if (so != NULL) 2935 (void) soabort(so); 2936 SYN_CACHE_PUT(sc); 2937 tcpstat.tcps_sc_aborted++; 2938 return ((struct socket *)(-1)); 2939 } 2940 2941 /* 2942 * This function is called when we get a RST for a 2943 * non-existant connection, so that we can see if the 2944 * connection is in the syn cache. If it is, zap it. 2945 */ 2946 2947 void 2948 syn_cache_reset(src, dst, th) 2949 struct sockaddr *src; 2950 struct sockaddr *dst; 2951 struct tcphdr *th; 2952 { 2953 struct syn_cache *sc; 2954 struct syn_cache_head *scp; 2955 int s = splsoftnet(); 2956 2957 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 2958 splx(s); 2959 return; 2960 } 2961 if (SEQ_LT(th->th_seq, sc->sc_irs) || 2962 SEQ_GT(th->th_seq, sc->sc_irs+1)) { 2963 splx(s); 2964 return; 2965 } 2966 SYN_CACHE_RM(sc); 2967 splx(s); 2968 tcpstat.tcps_sc_reset++; 2969 SYN_CACHE_PUT(sc); 2970 } 2971 2972 void 2973 syn_cache_unreach(src, dst, th) 2974 struct sockaddr *src; 2975 struct sockaddr *dst; 2976 struct tcphdr *th; 2977 { 2978 struct syn_cache *sc; 2979 struct syn_cache_head *scp; 2980 int s; 2981 2982 s = splsoftnet(); 2983 if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) { 2984 splx(s); 2985 return; 2986 } 2987 /* If the sequence number != sc_iss, then it's a bogus ICMP msg */ 2988 if (ntohl (th->th_seq) != sc->sc_iss) { 2989 splx(s); 2990 return; 2991 } 2992 2993 /* 2994 * If we've rertransmitted 3 times and this is our second error, 2995 * we remove the entry. Otherwise, we allow it to continue on. 2996 * This prevents us from incorrectly nuking an entry during a 2997 * spurious network outage. 2998 * 2999 * See tcp_notify(). 3000 */ 3001 if ((sc->sc_flags & SCF_UNREACH) == 0 || sc->sc_rxtshift < 3) { 3002 sc->sc_flags |= SCF_UNREACH; 3003 splx(s); 3004 return; 3005 } 3006 3007 SYN_CACHE_RM(sc); 3008 splx(s); 3009 tcpstat.tcps_sc_unreach++; 3010 SYN_CACHE_PUT(sc); 3011 } 3012 3013 /* 3014 * Given a LISTEN socket and an inbound SYN request, add 3015 * this to the syn cache, and send back a segment: 3016 * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK> 3017 * to the source. 3018 * 3019 * IMPORTANT NOTE: We do _NOT_ ACK data that might accompany the SYN. 3020 * Doing so would require that we hold onto the data and deliver it 3021 * to the application. However, if we are the target of a SYN-flood 3022 * DoS attack, an attacker could send data which would eventually 3023 * consume all available buffer space if it were ACKed. By not ACKing 3024 * the data, we avoid this DoS scenario. 3025 */ 3026 3027 int 3028 syn_cache_add(src, dst, th, hlen, so, m, optp, optlen, oi) 3029 struct sockaddr *src; 3030 struct sockaddr *dst; 3031 struct tcphdr *th; 3032 unsigned int hlen; 3033 struct socket *so; 3034 struct mbuf *m; 3035 u_char *optp; 3036 int optlen; 3037 struct tcp_opt_info *oi; 3038 { 3039 struct tcpcb tb, *tp; 3040 long win; 3041 struct syn_cache *sc; 3042 struct syn_cache_head *scp; 3043 struct mbuf *ipopts; 3044 #ifdef IPSEC 3045 size_t ipsechdrsiz; 3046 #endif 3047 3048 tp = sototcpcb(so); 3049 3050 /* 3051 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN 3052 * in_broadcast() should never return true on a received 3053 * packet with M_BCAST not set. 3054 */ 3055 if (m->m_flags & (M_BCAST|M_MCAST)) 3056 return 0; 3057 #ifdef INET6 3058 if (m->m_flags & M_ANYCAST6) 3059 return 0; 3060 #endif 3061 3062 switch (src->sa_family) { 3063 case AF_INET: 3064 if (IN_MULTICAST(((struct sockaddr_in *)src)->sin_addr.s_addr) 3065 || IN_MULTICAST(((struct sockaddr_in *)dst)->sin_addr.s_addr)) 3066 return 0; 3067 #ifdef IPSEC 3068 ipsechdrsiz = ipsec4_hdrsiz_tcp(tp); 3069 #endif 3070 break; 3071 #ifdef INET6 3072 case AF_INET6: 3073 if (IN6_IS_ADDR_MULTICAST(&((struct sockaddr_in6 *)src)->sin6_addr) 3074 || IN6_IS_ADDR_MULTICAST(&((struct sockaddr_in6 *)dst)->sin6_addr)) 3075 return 0; 3076 #if defined(IPSEC) && !defined(TCP6) 3077 ipsechdrsiz = ipsec6_hdrsiz_tcp(tp); 3078 #endif 3079 break; 3080 #endif 3081 } 3082 3083 /* 3084 * Initialize some local state. 3085 */ 3086 win = sbspace(&so->so_rcv); 3087 if (win > TCP_MAXWIN) 3088 win = TCP_MAXWIN; 3089 3090 if (src->sa_family == AF_INET) { 3091 /* 3092 * Remember the IP options, if any. 3093 */ 3094 ipopts = ip_srcroute(); 3095 } else 3096 ipopts = NULL; 3097 3098 if (optp) { 3099 tb.t_flags = tcp_do_rfc1323 ? (TF_REQ_SCALE|TF_REQ_TSTMP) : 0; 3100 tcp_dooptions(&tb, optp, optlen, th, oi); 3101 } else 3102 tb.t_flags = 0; 3103 3104 /* 3105 * See if we already have an entry for this connection. 3106 * If we do, resend the SYN,ACK. We do not count this 3107 * as a retransmission (XXX though maybe we should). 3108 */ 3109 if ((sc = syn_cache_lookup(src, dst, &scp)) != NULL) { 3110 tcpstat.tcps_sc_dupesyn++; 3111 if (ipopts) { 3112 /* 3113 * If we were remembering a previous source route, 3114 * forget it and use the new one we've been given. 3115 */ 3116 if (sc->sc_ipopts) 3117 (void) m_free(sc->sc_ipopts); 3118 sc->sc_ipopts = ipopts; 3119 } 3120 sc->sc_timestamp = tb.ts_recent; 3121 if (syn_cache_respond(sc, m) == 0) { 3122 tcpstat.tcps_sndacks++; 3123 tcpstat.tcps_sndtotal++; 3124 } 3125 return (1); 3126 } 3127 3128 sc = pool_get(&syn_cache_pool, PR_NOWAIT); 3129 if (sc == NULL) { 3130 if (ipopts) 3131 (void) m_free(ipopts); 3132 return (0); 3133 } 3134 3135 /* 3136 * Fill in the cache, and put the necessary IP and TCP 3137 * options into the reply. 3138 */ 3139 bzero(sc, sizeof(struct syn_cache)); 3140 bcopy(src, &sc->sc_src, src->sa_len); 3141 bcopy(dst, &sc->sc_dst, dst->sa_len); 3142 sc->sc_flags = 0; 3143 sc->sc_ipopts = ipopts; 3144 sc->sc_irs = th->th_seq; 3145 sc->sc_iss = tcp_new_iss(sc, sizeof(struct syn_cache), 0); 3146 sc->sc_peermaxseg = oi->maxseg; 3147 sc->sc_ourmaxseg = tcp_mss_to_advertise(m->m_flags & M_PKTHDR ? 3148 m->m_pkthdr.rcvif : NULL); 3149 #ifdef IPSEC 3150 if (ipsechdrsiz < sc->sc_ourmaxseg) 3151 sc->sc_ourmaxseg -= ipsechdrsiz; 3152 #endif 3153 sc->sc_win = win; 3154 sc->sc_timestamp = tb.ts_recent; 3155 if (tcp_do_rfc1323 && (tb.t_flags & TF_RCVD_TSTMP)) 3156 sc->sc_flags |= SCF_TIMESTAMP; 3157 if ((tb.t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 3158 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 3159 sc->sc_requested_s_scale = tb.requested_s_scale; 3160 sc->sc_request_r_scale = 0; 3161 while (sc->sc_request_r_scale < TCP_MAX_WINSHIFT && 3162 TCP_MAXWIN << sc->sc_request_r_scale < 3163 so->so_rcv.sb_hiwat) 3164 sc->sc_request_r_scale++; 3165 } else { 3166 sc->sc_requested_s_scale = 15; 3167 sc->sc_request_r_scale = 15; 3168 } 3169 sc->sc_so = so; 3170 if (syn_cache_respond(sc, m) == 0) { 3171 syn_cache_insert(sc); 3172 tcpstat.tcps_sndacks++; 3173 tcpstat.tcps_sndtotal++; 3174 } else { 3175 SYN_CACHE_PUT(sc); 3176 tcpstat.tcps_sc_dropped++; 3177 } 3178 return (1); 3179 } 3180 3181 int 3182 syn_cache_respond(sc, m) 3183 struct syn_cache *sc; 3184 struct mbuf *m; 3185 { 3186 struct route *ro = &sc->sc_route4; 3187 struct rtentry *rt; 3188 u_int8_t *optp; 3189 int optlen, error; 3190 u_int16_t tlen; 3191 struct ip *ip = NULL; 3192 #ifdef INET6 3193 struct ip6_hdr *ip6 = NULL; 3194 #endif 3195 struct tcphdr *th; 3196 u_int hlen; 3197 3198 switch (sc->sc_src.sa.sa_family) { 3199 case AF_INET: 3200 hlen = sizeof(struct ip); 3201 break; 3202 #ifdef INET6 3203 case AF_INET6: 3204 hlen = sizeof(struct ip6_hdr); 3205 break; 3206 #endif 3207 default: 3208 if (m) 3209 m_freem(m); 3210 return EAFNOSUPPORT; 3211 } 3212 3213 /* Compute the size of the TCP options. */ 3214 optlen = 4 + (sc->sc_request_r_scale != 15 ? 4 : 0) + 3215 ((sc->sc_flags & SCF_TIMESTAMP) ? TCPOLEN_TSTAMP_APPA : 0); 3216 3217 tlen = hlen + sizeof(struct tcphdr) + optlen; 3218 3219 /* 3220 * Create the IP+TCP header from scratch. Reuse the received mbuf 3221 * if possible. 3222 */ 3223 if (m != NULL) { 3224 m_freem(m->m_next); 3225 m->m_next = NULL; 3226 MRESETDATA(m); 3227 } else { 3228 MGETHDR(m, M_DONTWAIT, MT_DATA); 3229 if (m == NULL) 3230 return (ENOBUFS); 3231 } 3232 3233 /* Fixup the mbuf. */ 3234 m->m_data += max_linkhdr; 3235 m->m_len = m->m_pkthdr.len = tlen; 3236 #ifdef IPSEC 3237 /* use IPsec policy on listening socket, on SYN ACK */ 3238 m->m_pkthdr.rcvif = (struct ifnet *)sc->sc_so; 3239 #else 3240 m->m_pkthdr.rcvif = NULL; 3241 #endif 3242 memset(mtod(m, u_char *), 0, tlen); 3243 3244 switch (sc->sc_src.sa.sa_family) { 3245 case AF_INET: 3246 ip = mtod(m, struct ip *); 3247 ip->ip_dst = sc->sc_src.sin.sin_addr; 3248 ip->ip_src = sc->sc_dst.sin.sin_addr; 3249 ip->ip_p = IPPROTO_TCP; 3250 th = (struct tcphdr *)(ip + 1); 3251 th->th_dport = sc->sc_src.sin.sin_port; 3252 th->th_sport = sc->sc_dst.sin.sin_port; 3253 break; 3254 #ifdef INET6 3255 case AF_INET6: 3256 ip6 = mtod(m, struct ip6_hdr *); 3257 ip6->ip6_dst = sc->sc_src.sin6.sin6_addr; 3258 ip6->ip6_src = sc->sc_dst.sin6.sin6_addr; 3259 ip6->ip6_nxt = IPPROTO_TCP; 3260 /* ip6_plen will be updated in ip6_output() */ 3261 th = (struct tcphdr *)(ip6 + 1); 3262 th->th_dport = sc->sc_src.sin6.sin6_port; 3263 th->th_sport = sc->sc_dst.sin6.sin6_port; 3264 break; 3265 #endif 3266 default: 3267 th = NULL; 3268 } 3269 3270 th->th_seq = htonl(sc->sc_iss); 3271 th->th_ack = htonl(sc->sc_irs + 1); 3272 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2; 3273 th->th_flags = TH_SYN|TH_ACK; 3274 th->th_win = htons(sc->sc_win); 3275 /* th_sum already 0 */ 3276 /* th_urp already 0 */ 3277 3278 /* Tack on the TCP options. */ 3279 optp = (u_int8_t *)(th + 1); 3280 *optp++ = TCPOPT_MAXSEG; 3281 *optp++ = 4; 3282 *optp++ = (sc->sc_ourmaxseg >> 8) & 0xff; 3283 *optp++ = sc->sc_ourmaxseg & 0xff; 3284 3285 if (sc->sc_request_r_scale != 15) { 3286 *((u_int32_t *)optp) = htonl(TCPOPT_NOP << 24 | 3287 TCPOPT_WINDOW << 16 | TCPOLEN_WINDOW << 8 | 3288 sc->sc_request_r_scale); 3289 optp += 4; 3290 } 3291 3292 if (sc->sc_flags & SCF_TIMESTAMP) { 3293 u_int32_t *lp = (u_int32_t *)(optp); 3294 /* Form timestamp option as shown in appendix A of RFC 1323. */ 3295 *lp++ = htonl(TCPOPT_TSTAMP_HDR); 3296 *lp++ = htonl(tcp_now); 3297 *lp = htonl(sc->sc_timestamp); 3298 optp += TCPOLEN_TSTAMP_APPA; 3299 } 3300 3301 /* Compute the packet's checksum. */ 3302 switch (sc->sc_src.sa.sa_family) { 3303 case AF_INET: 3304 ip->ip_len = htons(tlen - hlen); 3305 th->th_sum = 0; 3306 th->th_sum = in_cksum(m, tlen); 3307 break; 3308 #ifdef INET6 3309 case AF_INET6: 3310 ip6->ip6_plen = htons(tlen - hlen); 3311 th->th_sum = 0; 3312 th->th_sum = in6_cksum(m, IPPROTO_TCP, hlen, tlen - hlen); 3313 break; 3314 #endif 3315 } 3316 3317 /* 3318 * Fill in some straggling IP bits. Note the stack expects 3319 * ip_len to be in host order, for convenience. 3320 */ 3321 switch (sc->sc_src.sa.sa_family) { 3322 case AF_INET: 3323 ip->ip_len = tlen; 3324 ip->ip_ttl = ip_defttl; 3325 /* XXX tos? */ 3326 break; 3327 #ifdef INET6 3328 case AF_INET6: 3329 ip6->ip6_vfc = IPV6_VERSION; 3330 ip6->ip6_plen = htons(tlen - hlen); 3331 ip6->ip6_hlim = ip6_defhlim; 3332 /* XXX flowlabel? */ 3333 break; 3334 #endif 3335 } 3336 3337 /* 3338 * If we're doing Path MTU discovery, we need to set DF unless 3339 * the route's MTU is locked. If we don't yet know the route, 3340 * look it up now. We will copy this reference to the inpcb 3341 * when we finish creating the connection. 3342 */ 3343 if ((rt = ro->ro_rt) == NULL || (rt->rt_flags & RTF_UP) == 0) { 3344 if (ro->ro_rt != NULL) { 3345 RTFREE(ro->ro_rt); 3346 ro->ro_rt = NULL; 3347 } 3348 bcopy(&sc->sc_src, &ro->ro_dst, sc->sc_src.sa.sa_len); 3349 rtalloc(ro); 3350 if ((rt = ro->ro_rt) == NULL) { 3351 m_freem(m); 3352 switch (sc->sc_src.sa.sa_family) { 3353 case AF_INET: 3354 ipstat.ips_noroute++; 3355 break; 3356 #ifdef INET6 3357 case AF_INET6: 3358 ip6stat.ip6s_noroute++; 3359 break; 3360 #endif 3361 } 3362 return (EHOSTUNREACH); 3363 } 3364 } 3365 3366 switch (sc->sc_src.sa.sa_family) { 3367 case AF_INET: 3368 if (ip_mtudisc != 0 && (rt->rt_rmx.rmx_locks & RTV_MTU) == 0) 3369 ip->ip_off |= IP_DF; 3370 3371 /* ...and send it off! */ 3372 error = ip_output(m, sc->sc_ipopts, ro, 0, NULL); 3373 break; 3374 #ifdef INET6 3375 case AF_INET6: 3376 error = ip6_output(m, NULL /*XXX*/, (struct route_in6 *)ro, 3377 0, NULL); 3378 break; 3379 #endif 3380 default: 3381 error = EAFNOSUPPORT; 3382 break; 3383 } 3384 return (error); 3385 } 3386
Indexes created Wed Sep 24 05:09:52 GMT 2025