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sys/netinet/tcp_input.c
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1 /* 2 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * @(#)tcp_input.c 8.12 (Berkeley) 5/24/95 34 * $FreeBSD: releng/5.1/sys/netinet/tcp_input.c 127036 2004-03-15 20:02:07Z fjoe $ 35 */ 36 37 #include "opt_ipfw.h" /* for ipfw_fwd */ 38 #include "opt_inet6.h" 39 #include "opt_ipsec.h" 40 #include "opt_mac.h" 41 #include "opt_tcpdebug.h" 42 #include "opt_tcp_input.h" 43 44 #include <sys/param.h> 45 #include <sys/kernel.h> 46 #include <sys/mac.h> 47 #include <sys/malloc.h> 48 #include <sys/mbuf.h> 49 #include <sys/proc.h> /* for proc0 declaration */ 50 #include <sys/protosw.h> 51 #include <sys/signalvar.h> 52 #include <sys/socket.h> 53 #include <sys/socketvar.h> 54 #include <sys/sysctl.h> 55 #include <sys/syslog.h> 56 #include <sys/systm.h> 57 58 #include <machine/cpu.h> /* before tcp_seq.h, for tcp_random18() */ 59 60 #include <vm/uma.h> 61 62 #include <net/if.h> 63 #include <net/route.h> 64 65 #include <netinet/in.h> 66 #include <netinet/in_pcb.h> 67 #include <netinet/in_systm.h> 68 #include <netinet/in_var.h> 69 #include <netinet/ip.h> 70 #include <netinet/ip_icmp.h> /* for ICMP_BANDLIM */ 71 #include <netinet/icmp_var.h> /* for ICMP_BANDLIM */ 72 #include <netinet/ip_var.h> 73 #include <netinet/ip6.h> 74 #include <netinet/icmp6.h> 75 #include <netinet6/in6_pcb.h> 76 #include <netinet6/ip6_var.h> 77 #include <netinet6/nd6.h> 78 #include <netinet/tcp.h> 79 #include <netinet/tcp_fsm.h> 80 #include <netinet/tcp_seq.h> 81 #include <netinet/tcp_timer.h> 82 #include <netinet/tcp_var.h> 83 #include <netinet6/tcp6_var.h> 84 #include <netinet/tcpip.h> 85 #ifdef TCPDEBUG 86 #include <netinet/tcp_debug.h> 87 #endif /* TCPDEBUG */ 88 89 #ifdef FAST_IPSEC 90 #include <netipsec/ipsec.h> 91 #include <netipsec/ipsec6.h> 92 #endif /*FAST_IPSEC*/ 93 94 #ifdef IPSEC 95 #include <netinet6/ipsec.h> 96 #include <netinet6/ipsec6.h> 97 #include <netkey/key.h> 98 #endif /*IPSEC*/ 99 100 #include <machine/in_cksum.h> 101 102 static const int tcprexmtthresh = 3; 103 tcp_cc tcp_ccgen; 104 105 struct tcpstat tcpstat; 106 SYSCTL_STRUCT(_net_inet_tcp, TCPCTL_STATS, stats, CTLFLAG_RW, 107 &tcpstat , tcpstat, "TCP statistics (struct tcpstat, netinet/tcp_var.h)"); 108 109 static int log_in_vain = 0; 110 SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_in_vain, CTLFLAG_RW, 111 &log_in_vain, 0, "Log all incoming TCP connections"); 112 113 static int blackhole = 0; 114 SYSCTL_INT(_net_inet_tcp, OID_AUTO, blackhole, CTLFLAG_RW, 115 &blackhole, 0, "Do not send RST when dropping refused connections"); 116 117 int tcp_delack_enabled = 1; 118 SYSCTL_INT(_net_inet_tcp, OID_AUTO, delayed_ack, CTLFLAG_RW, 119 &tcp_delack_enabled, 0, 120 "Delay ACK to try and piggyback it onto a data packet"); 121 122 #ifdef TCP_DROP_SYNFIN 123 static int drop_synfin = 0; 124 SYSCTL_INT(_net_inet_tcp, OID_AUTO, drop_synfin, CTLFLAG_RW, 125 &drop_synfin, 0, "Drop TCP packets with SYN+FIN set"); 126 #endif 127 128 static int tcp_do_rfc3042 = 0; 129 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3042, CTLFLAG_RW, 130 &tcp_do_rfc3042, 0, "Enable RFC 3042 (Limited Transmit)"); 131 132 static int tcp_do_rfc3390 = 0; 133 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3390, CTLFLAG_RW, 134 &tcp_do_rfc3390, 0, 135 "Enable RFC 3390 (Increasing TCP's Initial Congestion Window)"); 136 137 SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass, CTLFLAG_RW, 0, 138 "TCP Segment Reassembly Queue"); 139 140 static int tcp_reass_maxseg = 0; 141 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RD, 142 &tcp_reass_maxseg, 0, 143 "Global maximum number of TCP Segments in Reassembly Queue"); 144 145 int tcp_reass_qsize = 0; 146 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, cursegments, CTLFLAG_RD, 147 &tcp_reass_qsize, 0, 148 "Global number of TCP Segments currently in Reassembly Queue"); 149 150 static int tcp_reass_overflows = 0; 151 SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, overflows, CTLFLAG_RD, 152 &tcp_reass_overflows, 0, 153 "Global number of TCP Segment Reassembly Queue Overflows"); 154 155 struct inpcbhead tcb; 156 #define tcb6 tcb /* for KAME src sync over BSD*'s */ 157 struct inpcbinfo tcbinfo; 158 struct mtx *tcbinfo_mtx; 159 160 static void tcp_dooptions(struct tcpopt *, u_char *, int, int); 161 static void tcp_pulloutofband(struct socket *, 162 struct tcphdr *, struct mbuf *, int); 163 static int tcp_reass(struct tcpcb *, struct tcphdr *, int *, 164 struct mbuf *); 165 static void tcp_xmit_timer(struct tcpcb *, int); 166 static void tcp_newreno_partial_ack(struct tcpcb *, struct tcphdr *); 167 static int tcp_timewait(struct tcptw *, struct tcpopt *, 168 struct tcphdr *, struct mbuf *, int); 169 170 /* Neighbor Discovery, Neighbor Unreachability Detection Upper layer hint. */ 171 #ifdef INET6 172 #define ND6_HINT(tp) \ 173 do { \ 174 if ((tp) && (tp)->t_inpcb && \ 175 ((tp)->t_inpcb->inp_vflag & INP_IPV6) != 0 && \ 176 (tp)->t_inpcb->in6p_route.ro_rt) \ 177 nd6_nud_hint((tp)->t_inpcb->in6p_route.ro_rt, NULL, 0); \ 178 } while (0) 179 #else 180 #define ND6_HINT(tp) 181 #endif 182 183 /* 184 * Indicate whether this ack should be delayed. We can delay the ack if 185 * - there is no delayed ack timer in progress and 186 * - our last ack wasn't a 0-sized window. We never want to delay 187 * the ack that opens up a 0-sized window and 188 * - delayed acks are enabled or 189 * - this is a half-synchronized T/TCP connection. 190 */ 191 #define DELAY_ACK(tp) \ 192 ((!callout_active(tp->tt_delack) && \ 193 (tp->t_flags & TF_RXWIN0SENT) == 0) && \ 194 (tcp_delack_enabled || (tp->t_flags & TF_NEEDSYN))) 195 196 /* Initialize TCP reassembly queue */ 197 uma_zone_t tcp_reass_zone; 198 void 199 tcp_reass_init() 200 { 201 tcp_reass_maxseg = nmbclusters / 16; 202 TUNABLE_INT_FETCH("net.inet.tcp.reass.maxsegments", 203 &tcp_reass_maxseg); 204 tcp_reass_zone = uma_zcreate("tcpreass", sizeof (struct tseg_qent), 205 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_NOFREE); 206 uma_zone_set_max(tcp_reass_zone, tcp_reass_maxseg); 207 } 208 209 static int 210 tcp_reass(tp, th, tlenp, m) 211 register struct tcpcb *tp; 212 register struct tcphdr *th; 213 int *tlenp; 214 struct mbuf *m; 215 { 216 struct tseg_qent *q; 217 struct tseg_qent *p = NULL; 218 struct tseg_qent *nq; 219 struct tseg_qent *te = NULL; 220 struct socket *so = tp->t_inpcb->inp_socket; 221 int flags; 222 223 /* 224 * Call with th==0 after become established to 225 * force pre-ESTABLISHED data up to user socket. 226 */ 227 if (th == 0) 228 goto present; 229 230 /* 231 * Limit the number of segments in the reassembly queue to prevent 232 * holding on to too many segments (and thus running out of mbufs). 233 * Make sure to let the missing segment through which caused this 234 * queue. Always keep one global queue entry spare to be able to 235 * process the missing segment. 236 */ 237 if (th->th_seq != tp->rcv_nxt && 238 tcp_reass_qsize + 1 >= tcp_reass_maxseg) { 239 tcp_reass_overflows++; 240 tcpstat.tcps_rcvmemdrop++; 241 m_freem(m); 242 return (0); 243 } 244 245 /* 246 * Allocate a new queue entry. If we can't, or hit the zone limit 247 * just drop the pkt. 248 */ 249 te = uma_zalloc(tcp_reass_zone, M_NOWAIT); 250 if (te == NULL) { 251 tcpstat.tcps_rcvmemdrop++; 252 m_freem(m); 253 return (0); 254 } 255 tcp_reass_qsize++; 256 257 /* 258 * Find a segment which begins after this one does. 259 */ 260 LIST_FOREACH(q, &tp->t_segq, tqe_q) { 261 if (SEQ_GT(q->tqe_th->th_seq, th->th_seq)) 262 break; 263 p = q; 264 } 265 266 /* 267 * If there is a preceding segment, it may provide some of 268 * our data already. If so, drop the data from the incoming 269 * segment. If it provides all of our data, drop us. 270 */ 271 if (p != NULL) { 272 register int i; 273 /* conversion to int (in i) handles seq wraparound */ 274 i = p->tqe_th->th_seq + p->tqe_len - th->th_seq; 275 if (i > 0) { 276 if (i >= *tlenp) { 277 tcpstat.tcps_rcvduppack++; 278 tcpstat.tcps_rcvdupbyte += *tlenp; 279 m_freem(m); 280 uma_zfree(tcp_reass_zone, te); 281 tcp_reass_qsize--; 282 /* 283 * Try to present any queued data 284 * at the left window edge to the user. 285 * This is needed after the 3-WHS 286 * completes. 287 */ 288 goto present; /* ??? */ 289 } 290 m_adj(m, i); 291 *tlenp -= i; 292 th->th_seq += i; 293 } 294 } 295 tcpstat.tcps_rcvoopack++; 296 tcpstat.tcps_rcvoobyte += *tlenp; 297 298 /* 299 * While we overlap succeeding segments trim them or, 300 * if they are completely covered, dequeue them. 301 */ 302 while (q) { 303 register int i = (th->th_seq + *tlenp) - q->tqe_th->th_seq; 304 if (i <= 0) 305 break; 306 if (i < q->tqe_len) { 307 q->tqe_th->th_seq += i; 308 q->tqe_len -= i; 309 m_adj(q->tqe_m, i); 310 break; 311 } 312 313 nq = LIST_NEXT(q, tqe_q); 314 LIST_REMOVE(q, tqe_q); 315 m_freem(q->tqe_m); 316 uma_zfree(tcp_reass_zone, q); 317 tcp_reass_qsize--; 318 q = nq; 319 } 320 321 /* Insert the new segment queue entry into place. */ 322 te->tqe_m = m; 323 te->tqe_th = th; 324 te->tqe_len = *tlenp; 325 326 if (p == NULL) { 327 LIST_INSERT_HEAD(&tp->t_segq, te, tqe_q); 328 } else { 329 LIST_INSERT_AFTER(p, te, tqe_q); 330 } 331 332 present: 333 /* 334 * Present data to user, advancing rcv_nxt through 335 * completed sequence space. 336 */ 337 if (!TCPS_HAVEESTABLISHED(tp->t_state)) 338 return (0); 339 q = LIST_FIRST(&tp->t_segq); 340 if (!q || q->tqe_th->th_seq != tp->rcv_nxt) 341 return (0); 342 do { 343 tp->rcv_nxt += q->tqe_len; 344 flags = q->tqe_th->th_flags & TH_FIN; 345 nq = LIST_NEXT(q, tqe_q); 346 LIST_REMOVE(q, tqe_q); 347 if (so->so_state & SS_CANTRCVMORE) 348 m_freem(q->tqe_m); 349 else 350 sbappend(&so->so_rcv, q->tqe_m); 351 uma_zfree(tcp_reass_zone, q); 352 tcp_reass_qsize--; 353 q = nq; 354 } while (q && q->tqe_th->th_seq == tp->rcv_nxt); 355 ND6_HINT(tp); 356 sorwakeup(so); 357 return (flags); 358 } 359 360 /* 361 * TCP input routine, follows pages 65-76 of the 362 * protocol specification dated September, 1981 very closely. 363 */ 364 #ifdef INET6 365 int 366 tcp6_input(mp, offp, proto) 367 struct mbuf **mp; 368 int *offp, proto; 369 { 370 register struct mbuf *m = *mp; 371 struct in6_ifaddr *ia6; 372 373 IP6_EXTHDR_CHECK(m, *offp, sizeof(struct tcphdr), IPPROTO_DONE); 374 375 /* 376 * draft-itojun-ipv6-tcp-to-anycast 377 * better place to put this in? 378 */ 379 ia6 = ip6_getdstifaddr(m); 380 if (ia6 && (ia6->ia6_flags & IN6_IFF_ANYCAST)) { 381 struct ip6_hdr *ip6; 382 383 ip6 = mtod(m, struct ip6_hdr *); 384 icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR, 385 (caddr_t)&ip6->ip6_dst - (caddr_t)ip6); 386 return IPPROTO_DONE; 387 } 388 389 tcp_input(m, *offp); 390 return IPPROTO_DONE; 391 } 392 #endif 393 394 void 395 tcp_input(m, off0) 396 register struct mbuf *m; 397 int off0; 398 { 399 register struct tcphdr *th; 400 register struct ip *ip = NULL; 401 register struct ipovly *ipov; 402 register struct inpcb *inp = NULL; 403 u_char *optp = NULL; 404 int optlen = 0; 405 int len, tlen, off; 406 int drop_hdrlen; 407 register struct tcpcb *tp = 0; 408 register int thflags; 409 struct socket *so = 0; 410 int todrop, acked, ourfinisacked, needoutput = 0; 411 u_long tiwin; 412 struct tcpopt to; /* options in this segment */ 413 struct rmxp_tao *taop; /* pointer to our TAO cache entry */ 414 struct rmxp_tao tao_noncached; /* in case there's no cached entry */ 415 int headlocked = 0; 416 struct sockaddr_in *next_hop = NULL; 417 int rstreason; /* For badport_bandlim accounting purposes */ 418 419 struct ip6_hdr *ip6 = NULL; 420 #ifdef INET6 421 int isipv6; 422 #else 423 const int isipv6 = 0; 424 #endif 425 426 #ifdef TCPDEBUG 427 /* 428 * The size of tcp_saveipgen must be the size of the max ip header, 429 * now IPv6. 430 */ 431 u_char tcp_saveipgen[40]; 432 struct tcphdr tcp_savetcp; 433 short ostate = 0; 434 #endif 435 436 /* Grab info from MT_TAG mbufs prepended to the chain. */ 437 for (;m && m->m_type == MT_TAG; m = m->m_next) { 438 if (m->_m_tag_id == PACKET_TAG_IPFORWARD) 439 next_hop = (struct sockaddr_in *)m->m_hdr.mh_data; 440 } 441 #ifdef INET6 442 isipv6 = (mtod(m, struct ip *)->ip_v == 6) ? 1 : 0; 443 #endif 444 bzero((char *)&to, sizeof(to)); 445 446 tcpstat.tcps_rcvtotal++; 447 448 if (isipv6) { 449 /* IP6_EXTHDR_CHECK() is already done at tcp6_input() */ 450 ip6 = mtod(m, struct ip6_hdr *); 451 tlen = sizeof(*ip6) + ntohs(ip6->ip6_plen) - off0; 452 if (in6_cksum(m, IPPROTO_TCP, off0, tlen)) { 453 tcpstat.tcps_rcvbadsum++; 454 goto drop; 455 } 456 th = (struct tcphdr *)((caddr_t)ip6 + off0); 457 458 /* 459 * Be proactive about unspecified IPv6 address in source. 460 * As we use all-zero to indicate unbounded/unconnected pcb, 461 * unspecified IPv6 address can be used to confuse us. 462 * 463 * Note that packets with unspecified IPv6 destination is 464 * already dropped in ip6_input. 465 */ 466 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 467 /* XXX stat */ 468 goto drop; 469 } 470 } else { 471 /* 472 * Get IP and TCP header together in first mbuf. 473 * Note: IP leaves IP header in first mbuf. 474 */ 475 if (off0 > sizeof (struct ip)) { 476 ip_stripoptions(m, (struct mbuf *)0); 477 off0 = sizeof(struct ip); 478 } 479 if (m->m_len < sizeof (struct tcpiphdr)) { 480 if ((m = m_pullup(m, sizeof (struct tcpiphdr))) == 0) { 481 tcpstat.tcps_rcvshort++; 482 return; 483 } 484 } 485 ip = mtod(m, struct ip *); 486 ipov = (struct ipovly *)ip; 487 th = (struct tcphdr *)((caddr_t)ip + off0); 488 tlen = ip->ip_len; 489 490 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) { 491 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 492 th->th_sum = m->m_pkthdr.csum_data; 493 else 494 th->th_sum = in_pseudo(ip->ip_src.s_addr, 495 ip->ip_dst.s_addr, 496 htonl(m->m_pkthdr.csum_data + 497 ip->ip_len + 498 IPPROTO_TCP)); 499 th->th_sum ^= 0xffff; 500 } else { 501 /* 502 * Checksum extended TCP header and data. 503 */ 504 len = sizeof (struct ip) + tlen; 505 bzero(ipov->ih_x1, sizeof(ipov->ih_x1)); 506 ipov->ih_len = (u_short)tlen; 507 ipov->ih_len = htons(ipov->ih_len); 508 th->th_sum = in_cksum(m, len); 509 } 510 if (th->th_sum) { 511 tcpstat.tcps_rcvbadsum++; 512 goto drop; 513 } 514 #ifdef INET6 515 /* Re-initialization for later version check */ 516 ip->ip_v = IPVERSION; 517 #endif 518 } 519 520 /* 521 * Check that TCP offset makes sense, 522 * pull out TCP options and adjust length. XXX 523 */ 524 off = th->th_off << 2; 525 if (off < sizeof (struct tcphdr) || off > tlen) { 526 tcpstat.tcps_rcvbadoff++; 527 goto drop; 528 } 529 tlen -= off; /* tlen is used instead of ti->ti_len */ 530 if (off > sizeof (struct tcphdr)) { 531 if (isipv6) { 532 IP6_EXTHDR_CHECK(m, off0, off, ); 533 ip6 = mtod(m, struct ip6_hdr *); 534 th = (struct tcphdr *)((caddr_t)ip6 + off0); 535 } else { 536 if (m->m_len < sizeof(struct ip) + off) { 537 if ((m = m_pullup(m, sizeof (struct ip) + off)) 538 == 0) { 539 tcpstat.tcps_rcvshort++; 540 return; 541 } 542 ip = mtod(m, struct ip *); 543 ipov = (struct ipovly *)ip; 544 th = (struct tcphdr *)((caddr_t)ip + off0); 545 } 546 } 547 optlen = off - sizeof (struct tcphdr); 548 optp = (u_char *)(th + 1); 549 } 550 thflags = th->th_flags; 551 552 #ifdef TCP_DROP_SYNFIN 553 /* 554 * If the drop_synfin option is enabled, drop all packets with 555 * both the SYN and FIN bits set. This prevents e.g. nmap from 556 * identifying the TCP/IP stack. 557 * 558 * This is a violation of the TCP specification. 559 */ 560 if (drop_synfin && (thflags & (TH_SYN|TH_FIN)) == (TH_SYN|TH_FIN)) 561 goto drop; 562 #endif 563 564 /* 565 * Convert TCP protocol specific fields to host format. 566 */ 567 th->th_seq = ntohl(th->th_seq); 568 th->th_ack = ntohl(th->th_ack); 569 th->th_win = ntohs(th->th_win); 570 th->th_urp = ntohs(th->th_urp); 571 572 /* 573 * Delay dropping TCP, IP headers, IPv6 ext headers, and TCP options, 574 * until after ip6_savecontrol() is called and before other functions 575 * which don't want those proto headers. 576 * Because ip6_savecontrol() is going to parse the mbuf to 577 * search for data to be passed up to user-land, it wants mbuf 578 * parameters to be unchanged. 579 * XXX: the call of ip6_savecontrol() has been obsoleted based on 580 * latest version of the advanced API (20020110). 581 */ 582 drop_hdrlen = off0 + off; 583 584 /* 585 * Locate pcb for segment. 586 */ 587 INP_INFO_WLOCK(&tcbinfo); 588 headlocked = 1; 589 findpcb: 590 /* IPFIREWALL_FORWARD section */ 591 if (next_hop != NULL && isipv6 == 0) { /* IPv6 support is not yet */ 592 /* 593 * Transparently forwarded. Pretend to be the destination. 594 * already got one like this? 595 */ 596 inp = in_pcblookup_hash(&tcbinfo, ip->ip_src, th->th_sport, 597 ip->ip_dst, th->th_dport, 598 0, m->m_pkthdr.rcvif); 599 if (!inp) { 600 /* It's new. Try find the ambushing socket. */ 601 inp = in_pcblookup_hash(&tcbinfo, 602 ip->ip_src, th->th_sport, 603 next_hop->sin_addr, 604 next_hop->sin_port ? 605 ntohs(next_hop->sin_port) : 606 th->th_dport, 607 1, m->m_pkthdr.rcvif); 608 } 609 } else { 610 if (isipv6) 611 inp = in6_pcblookup_hash(&tcbinfo, 612 &ip6->ip6_src, th->th_sport, 613 &ip6->ip6_dst, th->th_dport, 614 1, m->m_pkthdr.rcvif); 615 else 616 inp = in_pcblookup_hash(&tcbinfo, 617 ip->ip_src, th->th_sport, 618 ip->ip_dst, th->th_dport, 619 1, m->m_pkthdr.rcvif); 620 } 621 622 #ifdef IPSEC 623 if (isipv6) { 624 if (inp != NULL && ipsec6_in_reject_so(m, inp->inp_socket)) { 625 ipsec6stat.in_polvio++; 626 goto drop; 627 } 628 } else { 629 if (inp != NULL && ipsec4_in_reject_so(m, inp->inp_socket)) { 630 ipsecstat.in_polvio++; 631 goto drop; 632 } 633 } 634 #endif 635 #ifdef FAST_IPSEC 636 if (isipv6) { 637 if (inp != NULL && ipsec6_in_reject(m, inp)) { 638 goto drop; 639 } 640 } else 641 if (inp != NULL && ipsec4_in_reject(m, inp)) { 642 goto drop; 643 } 644 #endif /*FAST_IPSEC*/ 645 646 /* 647 * If the state is CLOSED (i.e., TCB does not exist) then 648 * all data in the incoming segment is discarded. 649 * If the TCB exists but is in CLOSED state, it is embryonic, 650 * but should either do a listen or a connect soon. 651 */ 652 if (inp == NULL) { 653 if (log_in_vain) { 654 #ifdef INET6 655 char dbuf[INET6_ADDRSTRLEN+2], sbuf[INET6_ADDRSTRLEN+2]; 656 #else 657 char dbuf[4*sizeof "123"], sbuf[4*sizeof "123"]; 658 #endif 659 660 if (isipv6) { 661 strcpy(dbuf, "["); 662 strcpy(sbuf, "["); 663 strcat(dbuf, ip6_sprintf(&ip6->ip6_dst)); 664 strcat(sbuf, ip6_sprintf(&ip6->ip6_src)); 665 strcat(dbuf, "]"); 666 strcat(sbuf, "]"); 667 } else { 668 strcpy(dbuf, inet_ntoa(ip->ip_dst)); 669 strcpy(sbuf, inet_ntoa(ip->ip_src)); 670 } 671 switch (log_in_vain) { 672 case 1: 673 if ((thflags & TH_SYN) == 0) 674 break; 675 case 2: 676 log(LOG_INFO, 677 "Connection attempt to TCP %s:%d " 678 "from %s:%d flags:0x%02x\n", 679 dbuf, ntohs(th->th_dport), sbuf, 680 ntohs(th->th_sport), thflags); 681 break; 682 default: 683 break; 684 } 685 } 686 if (blackhole) { 687 switch (blackhole) { 688 case 1: 689 if (thflags & TH_SYN) 690 goto drop; 691 break; 692 case 2: 693 goto drop; 694 default: 695 goto drop; 696 } 697 } 698 rstreason = BANDLIM_RST_CLOSEDPORT; 699 goto dropwithreset; 700 } 701 INP_LOCK(inp); 702 if (inp->inp_vflag & INP_TIMEWAIT) { 703 /* 704 * The only option of relevance is TOF_CC, and only if 705 * present in a SYN segment. See tcp_timewait(). 706 */ 707 if (thflags & TH_SYN) 708 tcp_dooptions(&to, optp, optlen, 1); 709 if (tcp_timewait((struct tcptw *)inp->inp_ppcb, 710 &to, th, m, tlen)) 711 goto findpcb; 712 /* 713 * tcp_timewait unlocks inp. 714 */ 715 INP_INFO_WUNLOCK(&tcbinfo); 716 return; 717 } 718 tp = intotcpcb(inp); 719 if (tp == 0) { 720 INP_UNLOCK(inp); 721 rstreason = BANDLIM_RST_CLOSEDPORT; 722 goto dropwithreset; 723 } 724 if (tp->t_state == TCPS_CLOSED) 725 goto drop; 726 727 /* Unscale the window into a 32-bit value. */ 728 if ((thflags & TH_SYN) == 0) 729 tiwin = th->th_win << tp->snd_scale; 730 else 731 tiwin = th->th_win; 732 733 so = inp->inp_socket; 734 #ifdef MAC 735 if (mac_check_socket_deliver(so, m)) 736 goto drop; 737 #endif 738 #ifdef TCPDEBUG 739 if (so->so_options & SO_DEBUG) { 740 ostate = tp->t_state; 741 if (isipv6) 742 bcopy((char *)ip6, (char *)tcp_saveipgen, sizeof(*ip6)); 743 else 744 bcopy((char *)ip, (char *)tcp_saveipgen, sizeof(*ip)); 745 tcp_savetcp = *th; 746 } 747 #endif 748 if (so->so_options & SO_ACCEPTCONN) { 749 struct in_conninfo inc; 750 751 #ifdef INET6 752 inc.inc_isipv6 = isipv6; 753 #endif 754 if (isipv6) { 755 inc.inc6_faddr = ip6->ip6_src; 756 inc.inc6_laddr = ip6->ip6_dst; 757 inc.inc6_route.ro_rt = NULL; /* XXX */ 758 } else { 759 inc.inc_faddr = ip->ip_src; 760 inc.inc_laddr = ip->ip_dst; 761 inc.inc_route.ro_rt = NULL; /* XXX */ 762 } 763 inc.inc_fport = th->th_sport; 764 inc.inc_lport = th->th_dport; 765 766 /* 767 * If the state is LISTEN then ignore segment if it contains 768 * a RST. If the segment contains an ACK then it is bad and 769 * send a RST. If it does not contain a SYN then it is not 770 * interesting; drop it. 771 * 772 * If the state is SYN_RECEIVED (syncache) and seg contains 773 * an ACK, but not for our SYN/ACK, send a RST. If the seg 774 * contains a RST, check the sequence number to see if it 775 * is a valid reset segment. 776 */ 777 if ((thflags & (TH_RST|TH_ACK|TH_SYN)) != TH_SYN) { 778 if ((thflags & (TH_RST|TH_ACK|TH_SYN)) == TH_ACK) { 779 if (!syncache_expand(&inc, th, &so, m)) { 780 /* 781 * No syncache entry, or ACK was not 782 * for our SYN/ACK. Send a RST. 783 */ 784 tcpstat.tcps_badsyn++; 785 rstreason = BANDLIM_RST_OPENPORT; 786 goto dropwithreset; 787 } 788 if (so == NULL) { 789 /* 790 * Could not complete 3-way handshake, 791 * connection is being closed down, and 792 * syncache will free mbuf. 793 */ 794 INP_UNLOCK(inp); 795 INP_INFO_WUNLOCK(&tcbinfo); 796 return; 797 } 798 /* 799 * Socket is created in state SYN_RECEIVED. 800 * Continue processing segment. 801 */ 802 INP_UNLOCK(inp); 803 inp = sotoinpcb(so); 804 INP_LOCK(inp); 805 tp = intotcpcb(inp); 806 /* 807 * This is what would have happened in 808 * tcp_output() when the SYN,ACK was sent. 809 */ 810 tp->snd_up = tp->snd_una; 811 tp->snd_max = tp->snd_nxt = tp->iss + 1; 812 tp->last_ack_sent = tp->rcv_nxt; 813 /* 814 * RFC1323: The window in SYN & SYN/ACK 815 * segments is never scaled. 816 */ 817 tp->snd_wnd = tiwin; /* unscaled */ 818 goto after_listen; 819 } 820 if (thflags & TH_RST) { 821 syncache_chkrst(&inc, th); 822 goto drop; 823 } 824 if (thflags & TH_ACK) { 825 syncache_badack(&inc); 826 tcpstat.tcps_badsyn++; 827 rstreason = BANDLIM_RST_OPENPORT; 828 goto dropwithreset; 829 } 830 goto drop; 831 } 832 833 /* 834 * Segment's flags are (SYN) or (SYN|FIN). 835 */ 836 #ifdef INET6 837 /* 838 * If deprecated address is forbidden, 839 * we do not accept SYN to deprecated interface 840 * address to prevent any new inbound connection from 841 * getting established. 842 * When we do not accept SYN, we send a TCP RST, 843 * with deprecated source address (instead of dropping 844 * it). We compromise it as it is much better for peer 845 * to send a RST, and RST will be the final packet 846 * for the exchange. 847 * 848 * If we do not forbid deprecated addresses, we accept 849 * the SYN packet. RFC2462 does not suggest dropping 850 * SYN in this case. 851 * If we decipher RFC2462 5.5.4, it says like this: 852 * 1. use of deprecated addr with existing 853 * communication is okay - "SHOULD continue to be 854 * used" 855 * 2. use of it with new communication: 856 * (2a) "SHOULD NOT be used if alternate address 857 * with sufficient scope is available" 858 * (2b) nothing mentioned otherwise. 859 * Here we fall into (2b) case as we have no choice in 860 * our source address selection - we must obey the peer. 861 * 862 * The wording in RFC2462 is confusing, and there are 863 * multiple description text for deprecated address 864 * handling - worse, they are not exactly the same. 865 * I believe 5.5.4 is the best one, so we follow 5.5.4. 866 */ 867 if (isipv6 && !ip6_use_deprecated) { 868 struct in6_ifaddr *ia6; 869 870 if ((ia6 = ip6_getdstifaddr(m)) && 871 (ia6->ia6_flags & IN6_IFF_DEPRECATED)) { 872 INP_UNLOCK(inp); 873 tp = NULL; 874 rstreason = BANDLIM_RST_OPENPORT; 875 goto dropwithreset; 876 } 877 } 878 #endif 879 /* 880 * If it is from this socket, drop it, it must be forged. 881 * Don't bother responding if the destination was a broadcast. 882 */ 883 if (th->th_dport == th->th_sport) { 884 if (isipv6) { 885 if (IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, 886 &ip6->ip6_src)) 887 goto drop; 888 } else { 889 if (ip->ip_dst.s_addr == ip->ip_src.s_addr) 890 goto drop; 891 } 892 } 893 /* 894 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN 895 * 896 * Note that it is quite possible to receive unicast 897 * link-layer packets with a broadcast IP address. Use 898 * in_broadcast() to find them. 899 */ 900 if (m->m_flags & (M_BCAST|M_MCAST)) 901 goto drop; 902 if (isipv6) { 903 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 904 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) 905 goto drop; 906 } else { 907 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || 908 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 909 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || 910 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 911 goto drop; 912 } 913 /* 914 * SYN appears to be valid; create compressed TCP state 915 * for syncache, or perform t/tcp connection. 916 */ 917 if (so->so_qlen <= so->so_qlimit) { 918 tcp_dooptions(&to, optp, optlen, 1); 919 if (!syncache_add(&inc, &to, th, &so, m)) 920 goto drop; 921 if (so == NULL) { 922 /* 923 * Entry added to syncache, mbuf used to 924 * send SYN,ACK packet. 925 */ 926 KASSERT(headlocked, ("headlocked")); 927 INP_UNLOCK(inp); 928 INP_INFO_WUNLOCK(&tcbinfo); 929 return; 930 } 931 /* 932 * Segment passed TAO tests. 933 */ 934 INP_UNLOCK(inp); 935 inp = sotoinpcb(so); 936 INP_LOCK(inp); 937 tp = intotcpcb(inp); 938 tp->snd_wnd = tiwin; 939 tp->t_starttime = ticks; 940 tp->t_state = TCPS_ESTABLISHED; 941 942 /* 943 * T/TCP logic: 944 * If there is a FIN or if there is data, then 945 * delay SYN,ACK(SYN) in the hope of piggy-backing 946 * it on a response segment. Otherwise must send 947 * ACK now in case the other side is slow starting. 948 */ 949 if (thflags & TH_FIN || tlen != 0) 950 tp->t_flags |= (TF_DELACK | TF_NEEDSYN); 951 else 952 tp->t_flags |= (TF_ACKNOW | TF_NEEDSYN); 953 tcpstat.tcps_connects++; 954 soisconnected(so); 955 goto trimthenstep6; 956 } 957 goto drop; 958 } 959 after_listen: 960 961 /* XXX temp debugging */ 962 /* should not happen - syncache should pick up these connections */ 963 if (tp->t_state == TCPS_LISTEN) 964 panic("tcp_input: TCPS_LISTEN"); 965 966 /* 967 * Segment received on connection. 968 * Reset idle time and keep-alive timer. 969 */ 970 tp->t_rcvtime = ticks; 971 if (TCPS_HAVEESTABLISHED(tp->t_state)) 972 callout_reset(tp->tt_keep, tcp_keepidle, tcp_timer_keep, tp); 973 974 /* 975 * Process options. 976 * XXX this is tradtitional behavior, may need to be cleaned up. 977 */ 978 tcp_dooptions(&to, optp, optlen, thflags & TH_SYN); 979 if (thflags & TH_SYN) { 980 if (to.to_flags & TOF_SCALE) { 981 tp->t_flags |= TF_RCVD_SCALE; 982 tp->requested_s_scale = to.to_requested_s_scale; 983 } 984 if (to.to_flags & TOF_TS) { 985 tp->t_flags |= TF_RCVD_TSTMP; 986 tp->ts_recent = to.to_tsval; 987 tp->ts_recent_age = ticks; 988 } 989 if (to.to_flags & (TOF_CC|TOF_CCNEW)) 990 tp->t_flags |= TF_RCVD_CC; 991 if (to.to_flags & TOF_MSS) 992 tcp_mss(tp, to.to_mss); 993 } 994 995 /* 996 * Header prediction: check for the two common cases 997 * of a uni-directional data xfer. If the packet has 998 * no control flags, is in-sequence, the window didn't 999 * change and we're not retransmitting, it's a 1000 * candidate. If the length is zero and the ack moved 1001 * forward, we're the sender side of the xfer. Just 1002 * free the data acked & wake any higher level process 1003 * that was blocked waiting for space. If the length 1004 * is non-zero and the ack didn't move, we're the 1005 * receiver side. If we're getting packets in-order 1006 * (the reassembly queue is empty), add the data to 1007 * the socket buffer and note that we need a delayed ack. 1008 * Make sure that the hidden state-flags are also off. 1009 * Since we check for TCPS_ESTABLISHED above, it can only 1010 * be TH_NEEDSYN. 1011 */ 1012 if (tp->t_state == TCPS_ESTABLISHED && 1013 (thflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK && 1014 ((tp->t_flags & (TF_NEEDSYN|TF_NEEDFIN)) == 0) && 1015 ((to.to_flags & TOF_TS) == 0 || 1016 TSTMP_GEQ(to.to_tsval, tp->ts_recent)) && 1017 /* 1018 * Using the CC option is compulsory if once started: 1019 * the segment is OK if no T/TCP was negotiated or 1020 * if the segment has a CC option equal to CCrecv 1021 */ 1022 ((tp->t_flags & (TF_REQ_CC|TF_RCVD_CC)) != (TF_REQ_CC|TF_RCVD_CC) || 1023 ((to.to_flags & TOF_CC) != 0 && to.to_cc == tp->cc_recv)) && 1024 th->th_seq == tp->rcv_nxt && 1025 tiwin && tiwin == tp->snd_wnd && 1026 tp->snd_nxt == tp->snd_max) { 1027 1028 /* 1029 * If last ACK falls within this segment's sequence numbers, 1030 * record the timestamp. 1031 * NOTE that the test is modified according to the latest 1032 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 1033 */ 1034 if ((to.to_flags & TOF_TS) != 0 && 1035 SEQ_LEQ(th->th_seq, tp->last_ack_sent)) { 1036 tp->ts_recent_age = ticks; 1037 tp->ts_recent = to.to_tsval; 1038 } 1039 1040 if (tlen == 0) { 1041 if (SEQ_GT(th->th_ack, tp->snd_una) && 1042 SEQ_LEQ(th->th_ack, tp->snd_max) && 1043 tp->snd_cwnd >= tp->snd_wnd && 1044 ((!tcp_do_newreno && 1045 tp->t_dupacks < tcprexmtthresh) || 1046 (tcp_do_newreno && 1047 !SEQ_LT(tp->snd_una, tp->snd_recover)))) { 1048 KASSERT(headlocked, ("headlocked")); 1049 INP_INFO_WUNLOCK(&tcbinfo); 1050 /* 1051 * this is a pure ack for outstanding data. 1052 */ 1053 ++tcpstat.tcps_predack; 1054 /* 1055 * "bad retransmit" recovery 1056 */ 1057 if (tp->t_rxtshift == 1 && 1058 ticks < tp->t_badrxtwin) { 1059 ++tcpstat.tcps_sndrexmitbad; 1060 tp->snd_cwnd = tp->snd_cwnd_prev; 1061 tp->snd_ssthresh = 1062 tp->snd_ssthresh_prev; 1063 tp->snd_high = tp->snd_high_prev; 1064 tp->snd_nxt = tp->snd_max; 1065 tp->t_badrxtwin = 0; 1066 } 1067 1068 /* 1069 * Recalculate the transmit timer / rtt. 1070 * 1071 * Some boxes send broken timestamp replies 1072 * during the SYN+ACK phase, ignore 1073 * timestamps of 0 or we could calculate a 1074 * huge RTT and blow up the retransmit timer. 1075 */ 1076 if ((to.to_flags & TOF_TS) != 0 && 1077 to.to_tsecr) { 1078 tcp_xmit_timer(tp, 1079 ticks - to.to_tsecr + 1); 1080 } else if (tp->t_rtttime && 1081 SEQ_GT(th->th_ack, tp->t_rtseq)) { 1082 tcp_xmit_timer(tp, 1083 ticks - tp->t_rtttime); 1084 } 1085 tcp_xmit_bandwidth_limit(tp, th->th_ack); 1086 acked = th->th_ack - tp->snd_una; 1087 tcpstat.tcps_rcvackpack++; 1088 tcpstat.tcps_rcvackbyte += acked; 1089 sbdrop(&so->so_snd, acked); 1090 if (SEQ_GT(tp->snd_una, tp->snd_high) && 1091 SEQ_LEQ(th->th_ack, tp->snd_high)) 1092 tp->snd_high = th->th_ack - 1; 1093 tp->snd_una = tp->snd_recover = th->th_ack; 1094 /* 1095 * pull snd_wl2 up to prevent seq wrap relative 1096 * to th_ack. 1097 */ 1098 tp->snd_wl2 = th->th_ack; 1099 tp->t_dupacks = 0; 1100 m_freem(m); 1101 ND6_HINT(tp); /* some progress has been done */ 1102 1103 /* 1104 * If all outstanding data are acked, stop 1105 * retransmit timer, otherwise restart timer 1106 * using current (possibly backed-off) value. 1107 * If process is waiting for space, 1108 * wakeup/selwakeup/signal. If data 1109 * are ready to send, let tcp_output 1110 * decide between more output or persist. 1111 */ 1112 if (tp->snd_una == tp->snd_max) 1113 callout_stop(tp->tt_rexmt); 1114 else if (!callout_active(tp->tt_persist)) 1115 callout_reset(tp->tt_rexmt, 1116 tp->t_rxtcur, 1117 tcp_timer_rexmt, tp); 1118 1119 sowwakeup(so); 1120 if (so->so_snd.sb_cc) 1121 (void) tcp_output(tp); 1122 goto check_delack; 1123 } 1124 } else if (th->th_ack == tp->snd_una && 1125 LIST_EMPTY(&tp->t_segq) && 1126 tlen <= sbspace(&so->so_rcv)) { 1127 KASSERT(headlocked, ("headlocked")); 1128 INP_INFO_WUNLOCK(&tcbinfo); 1129 /* 1130 * this is a pure, in-sequence data packet 1131 * with nothing on the reassembly queue and 1132 * we have enough buffer space to take it. 1133 */ 1134 ++tcpstat.tcps_preddat; 1135 tp->rcv_nxt += tlen; 1136 /* 1137 * Pull snd_wl1 up to prevent seq wrap relative to 1138 * th_seq. 1139 */ 1140 tp->snd_wl1 = th->th_seq; 1141 /* 1142 * Pull rcv_up up to prevent seq wrap relative to 1143 * rcv_nxt. 1144 */ 1145 tp->rcv_up = tp->rcv_nxt; 1146 tcpstat.tcps_rcvpack++; 1147 tcpstat.tcps_rcvbyte += tlen; 1148 ND6_HINT(tp); /* some progress has been done */ 1149 /* 1150 * Add data to socket buffer. 1151 */ 1152 if (so->so_state & SS_CANTRCVMORE) { 1153 m_freem(m); 1154 } else { 1155 m_adj(m, drop_hdrlen); /* delayed header drop */ 1156 sbappend(&so->so_rcv, m); 1157 } 1158 sorwakeup(so); 1159 if (DELAY_ACK(tp)) { 1160 tp->t_flags |= TF_DELACK; 1161 } else { 1162 tp->t_flags |= TF_ACKNOW; 1163 tcp_output(tp); 1164 } 1165 goto check_delack; 1166 } 1167 } 1168 1169 /* 1170 * Calculate amount of space in receive window, 1171 * and then do TCP input processing. 1172 * Receive window is amount of space in rcv queue, 1173 * but not less than advertised window. 1174 */ 1175 { int win; 1176 1177 win = sbspace(&so->so_rcv); 1178 if (win < 0) 1179 win = 0; 1180 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 1181 } 1182 1183 switch (tp->t_state) { 1184 1185 /* 1186 * If the state is SYN_RECEIVED: 1187 * if seg contains an ACK, but not for our SYN/ACK, send a RST. 1188 */ 1189 case TCPS_SYN_RECEIVED: 1190 if ((thflags & TH_ACK) && 1191 (SEQ_LEQ(th->th_ack, tp->snd_una) || 1192 SEQ_GT(th->th_ack, tp->snd_max))) { 1193 rstreason = BANDLIM_RST_OPENPORT; 1194 goto dropwithreset; 1195 } 1196 break; 1197 1198 /* 1199 * If the state is SYN_SENT: 1200 * if seg contains an ACK, but not for our SYN, drop the input. 1201 * if seg contains a RST, then drop the connection. 1202 * if seg does not contain SYN, then drop it. 1203 * Otherwise this is an acceptable SYN segment 1204 * initialize tp->rcv_nxt and tp->irs 1205 * if seg contains ack then advance tp->snd_una 1206 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 1207 * arrange for segment to be acked (eventually) 1208 * continue processing rest of data/controls, beginning with URG 1209 */ 1210 case TCPS_SYN_SENT: 1211 if ((taop = tcp_gettaocache(&inp->inp_inc)) == NULL) { 1212 taop = &tao_noncached; 1213 bzero(taop, sizeof(*taop)); 1214 } 1215 1216 if ((thflags & TH_ACK) && 1217 (SEQ_LEQ(th->th_ack, tp->iss) || 1218 SEQ_GT(th->th_ack, tp->snd_max))) { 1219 /* 1220 * If we have a cached CCsent for the remote host, 1221 * hence we haven't just crashed and restarted, 1222 * do not send a RST. This may be a retransmission 1223 * from the other side after our earlier ACK was lost. 1224 * Our new SYN, when it arrives, will serve as the 1225 * needed ACK. 1226 */ 1227 if (taop->tao_ccsent != 0) 1228 goto drop; 1229 else { 1230 rstreason = BANDLIM_UNLIMITED; 1231 goto dropwithreset; 1232 } 1233 } 1234 if (thflags & TH_RST) { 1235 if (thflags & TH_ACK) 1236 tp = tcp_drop(tp, ECONNREFUSED); 1237 goto drop; 1238 } 1239 if ((thflags & TH_SYN) == 0) 1240 goto drop; 1241 tp->snd_wnd = th->th_win; /* initial send window */ 1242 tp->cc_recv = to.to_cc; /* foreign CC */ 1243 1244 tp->irs = th->th_seq; 1245 tcp_rcvseqinit(tp); 1246 if (thflags & TH_ACK) { 1247 /* 1248 * Our SYN was acked. If segment contains CC.ECHO 1249 * option, check it to make sure this segment really 1250 * matches our SYN. If not, just drop it as old 1251 * duplicate, but send an RST if we're still playing 1252 * by the old rules. If no CC.ECHO option, make sure 1253 * we don't get fooled into using T/TCP. 1254 */ 1255 if (to.to_flags & TOF_CCECHO) { 1256 if (tp->cc_send != to.to_ccecho) { 1257 if (taop->tao_ccsent != 0) 1258 goto drop; 1259 else { 1260 rstreason = BANDLIM_UNLIMITED; 1261 goto dropwithreset; 1262 } 1263 } 1264 } else 1265 tp->t_flags &= ~TF_RCVD_CC; 1266 tcpstat.tcps_connects++; 1267 soisconnected(so); 1268 #ifdef MAC 1269 mac_set_socket_peer_from_mbuf(m, so); 1270 #endif 1271 /* Do window scaling on this connection? */ 1272 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 1273 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 1274 tp->snd_scale = tp->requested_s_scale; 1275 tp->rcv_scale = tp->request_r_scale; 1276 } 1277 /* Segment is acceptable, update cache if undefined. */ 1278 if (taop->tao_ccsent == 0) 1279 taop->tao_ccsent = to.to_ccecho; 1280 1281 tp->rcv_adv += tp->rcv_wnd; 1282 tp->snd_una++; /* SYN is acked */ 1283 /* 1284 * If there's data, delay ACK; if there's also a FIN 1285 * ACKNOW will be turned on later. 1286 */ 1287 if (DELAY_ACK(tp) && tlen != 0) 1288 callout_reset(tp->tt_delack, tcp_delacktime, 1289 tcp_timer_delack, tp); 1290 else 1291 tp->t_flags |= TF_ACKNOW; 1292 /* 1293 * Received <SYN,ACK> in SYN_SENT[*] state. 1294 * Transitions: 1295 * SYN_SENT --> ESTABLISHED 1296 * SYN_SENT* --> FIN_WAIT_1 1297 */ 1298 tp->t_starttime = ticks; 1299 if (tp->t_flags & TF_NEEDFIN) { 1300 tp->t_state = TCPS_FIN_WAIT_1; 1301 tp->t_flags &= ~TF_NEEDFIN; 1302 thflags &= ~TH_SYN; 1303 } else { 1304 tp->t_state = TCPS_ESTABLISHED; 1305 callout_reset(tp->tt_keep, tcp_keepidle, 1306 tcp_timer_keep, tp); 1307 } 1308 } else { 1309 /* 1310 * Received initial SYN in SYN-SENT[*] state => 1311 * simultaneous open. If segment contains CC option 1312 * and there is a cached CC, apply TAO test. 1313 * If it succeeds, connection is * half-synchronized. 1314 * Otherwise, do 3-way handshake: 1315 * SYN-SENT -> SYN-RECEIVED 1316 * SYN-SENT* -> SYN-RECEIVED* 1317 * If there was no CC option, clear cached CC value. 1318 */ 1319 tp->t_flags |= TF_ACKNOW; 1320 callout_stop(tp->tt_rexmt); 1321 if (to.to_flags & TOF_CC) { 1322 if (taop->tao_cc != 0 && 1323 CC_GT(to.to_cc, taop->tao_cc)) { 1324 /* 1325 * update cache and make transition: 1326 * SYN-SENT -> ESTABLISHED* 1327 * SYN-SENT* -> FIN-WAIT-1* 1328 */ 1329 taop->tao_cc = to.to_cc; 1330 tp->t_starttime = ticks; 1331 if (tp->t_flags & TF_NEEDFIN) { 1332 tp->t_state = TCPS_FIN_WAIT_1; 1333 tp->t_flags &= ~TF_NEEDFIN; 1334 } else { 1335 tp->t_state = TCPS_ESTABLISHED; 1336 callout_reset(tp->tt_keep, 1337 tcp_keepidle, 1338 tcp_timer_keep, 1339 tp); 1340 } 1341 tp->t_flags |= TF_NEEDSYN; 1342 } else 1343 tp->t_state = TCPS_SYN_RECEIVED; 1344 } else { 1345 /* CC.NEW or no option => invalidate cache */ 1346 taop->tao_cc = 0; 1347 tp->t_state = TCPS_SYN_RECEIVED; 1348 } 1349 } 1350 1351 trimthenstep6: 1352 /* 1353 * Advance th->th_seq to correspond to first data byte. 1354 * If data, trim to stay within window, 1355 * dropping FIN if necessary. 1356 */ 1357 th->th_seq++; 1358 if (tlen > tp->rcv_wnd) { 1359 todrop = tlen - tp->rcv_wnd; 1360 m_adj(m, -todrop); 1361 tlen = tp->rcv_wnd; 1362 thflags &= ~TH_FIN; 1363 tcpstat.tcps_rcvpackafterwin++; 1364 tcpstat.tcps_rcvbyteafterwin += todrop; 1365 } 1366 tp->snd_wl1 = th->th_seq - 1; 1367 tp->rcv_up = th->th_seq; 1368 /* 1369 * Client side of transaction: already sent SYN and data. 1370 * If the remote host used T/TCP to validate the SYN, 1371 * our data will be ACK'd; if so, enter normal data segment 1372 * processing in the middle of step 5, ack processing. 1373 * Otherwise, goto step 6. 1374 */ 1375 if (thflags & TH_ACK) 1376 goto process_ACK; 1377 1378 goto step6; 1379 1380 /* 1381 * If the state is LAST_ACK or CLOSING or TIME_WAIT: 1382 * if segment contains a SYN and CC [not CC.NEW] option: 1383 * if state == TIME_WAIT and connection duration > MSL, 1384 * drop packet and send RST; 1385 * 1386 * if SEG.CC > CCrecv then is new SYN, and can implicitly 1387 * ack the FIN (and data) in retransmission queue. 1388 * Complete close and delete TCPCB. Then reprocess 1389 * segment, hoping to find new TCPCB in LISTEN state; 1390 * 1391 * else must be old SYN; drop it. 1392 * else do normal processing. 1393 */ 1394 case TCPS_LAST_ACK: 1395 case TCPS_CLOSING: 1396 case TCPS_TIME_WAIT: 1397 KASSERT(tp->t_state != TCPS_TIME_WAIT, ("timewait")); 1398 if ((thflags & TH_SYN) && 1399 (to.to_flags & TOF_CC) && tp->cc_recv != 0) { 1400 if (tp->t_state == TCPS_TIME_WAIT && 1401 (ticks - tp->t_starttime) > tcp_msl) { 1402 rstreason = BANDLIM_UNLIMITED; 1403 goto dropwithreset; 1404 } 1405 if (CC_GT(to.to_cc, tp->cc_recv)) { 1406 tp = tcp_close(tp); 1407 goto findpcb; 1408 } 1409 else 1410 goto drop; 1411 } 1412 break; /* continue normal processing */ 1413 } 1414 1415 /* 1416 * States other than LISTEN or SYN_SENT. 1417 * First check the RST flag and sequence number since reset segments 1418 * are exempt from the timestamp and connection count tests. This 1419 * fixes a bug introduced by the Stevens, vol. 2, p. 960 bugfix 1420 * below which allowed reset segments in half the sequence space 1421 * to fall though and be processed (which gives forged reset 1422 * segments with a random sequence number a 50 percent chance of 1423 * killing a connection). 1424 * Then check timestamp, if present. 1425 * Then check the connection count, if present. 1426 * Then check that at least some bytes of segment are within 1427 * receive window. If segment begins before rcv_nxt, 1428 * drop leading data (and SYN); if nothing left, just ack. 1429 * 1430 * 1431 * If the RST bit is set, check the sequence number to see 1432 * if this is a valid reset segment. 1433 * RFC 793 page 37: 1434 * In all states except SYN-SENT, all reset (RST) segments 1435 * are validated by checking their SEQ-fields. A reset is 1436 * valid if its sequence number is in the window. 1437 * Note: this does not take into account delayed ACKs, so 1438 * we should test against last_ack_sent instead of rcv_nxt. 1439 * The sequence number in the reset segment is normally an 1440 * echo of our outgoing acknowlegement numbers, but some hosts 1441 * send a reset with the sequence number at the rightmost edge 1442 * of our receive window, and we have to handle this case. 1443 * If we have multiple segments in flight, the intial reset 1444 * segment sequence numbers will be to the left of last_ack_sent, 1445 * but they will eventually catch up. 1446 * In any case, it never made sense to trim reset segments to 1447 * fit the receive window since RFC 1122 says: 1448 * 4.2.2.12 RST Segment: RFC-793 Section 3.4 1449 * 1450 * A TCP SHOULD allow a received RST segment to include data. 1451 * 1452 * DISCUSSION 1453 * It has been suggested that a RST segment could contain 1454 * ASCII text that encoded and explained the cause of the 1455 * RST. No standard has yet been established for such 1456 * data. 1457 * 1458 * If the reset segment passes the sequence number test examine 1459 * the state: 1460 * SYN_RECEIVED STATE: 1461 * If passive open, return to LISTEN state. 1462 * If active open, inform user that connection was refused. 1463 * ESTABLISHED, FIN_WAIT_1, FIN_WAIT_2, CLOSE_WAIT STATES: 1464 * Inform user that connection was reset, and close tcb. 1465 * CLOSING, LAST_ACK STATES: 1466 * Close the tcb. 1467 * TIME_WAIT STATE: 1468 * Drop the segment - see Stevens, vol. 2, p. 964 and 1469 * RFC 1337. 1470 */ 1471 if (thflags & TH_RST) { 1472 if (SEQ_GEQ(th->th_seq, tp->last_ack_sent) && 1473 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) { 1474 switch (tp->t_state) { 1475 1476 case TCPS_SYN_RECEIVED: 1477 so->so_error = ECONNREFUSED; 1478 goto close; 1479 1480 case TCPS_ESTABLISHED: 1481 case TCPS_FIN_WAIT_1: 1482 case TCPS_FIN_WAIT_2: 1483 case TCPS_CLOSE_WAIT: 1484 so->so_error = ECONNRESET; 1485 close: 1486 tp->t_state = TCPS_CLOSED; 1487 tcpstat.tcps_drops++; 1488 tp = tcp_close(tp); 1489 break; 1490 1491 case TCPS_CLOSING: 1492 case TCPS_LAST_ACK: 1493 tp = tcp_close(tp); 1494 break; 1495 1496 case TCPS_TIME_WAIT: 1497 KASSERT(tp->t_state != TCPS_TIME_WAIT, 1498 ("timewait")); 1499 break; 1500 } 1501 } 1502 goto drop; 1503 } 1504 1505 /* 1506 * RFC 1323 PAWS: If we have a timestamp reply on this segment 1507 * and it's less than ts_recent, drop it. 1508 */ 1509 if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent && 1510 TSTMP_LT(to.to_tsval, tp->ts_recent)) { 1511 1512 /* Check to see if ts_recent is over 24 days old. */ 1513 if ((int)(ticks - tp->ts_recent_age) > TCP_PAWS_IDLE) { 1514 /* 1515 * Invalidate ts_recent. If this segment updates 1516 * ts_recent, the age will be reset later and ts_recent 1517 * will get a valid value. If it does not, setting 1518 * ts_recent to zero will at least satisfy the 1519 * requirement that zero be placed in the timestamp 1520 * echo reply when ts_recent isn't valid. The 1521 * age isn't reset until we get a valid ts_recent 1522 * because we don't want out-of-order segments to be 1523 * dropped when ts_recent is old. 1524 */ 1525 tp->ts_recent = 0; 1526 } else { 1527 tcpstat.tcps_rcvduppack++; 1528 tcpstat.tcps_rcvdupbyte += tlen; 1529 tcpstat.tcps_pawsdrop++; 1530 if (tlen) 1531 goto dropafterack; 1532 goto drop; 1533 } 1534 } 1535 1536 /* 1537 * T/TCP mechanism 1538 * If T/TCP was negotiated and the segment doesn't have CC, 1539 * or if its CC is wrong then drop the segment. 1540 * RST segments do not have to comply with this. 1541 */ 1542 if ((tp->t_flags & (TF_REQ_CC|TF_RCVD_CC)) == (TF_REQ_CC|TF_RCVD_CC) && 1543 ((to.to_flags & TOF_CC) == 0 || tp->cc_recv != to.to_cc)) 1544 goto dropafterack; 1545 1546 /* 1547 * In the SYN-RECEIVED state, validate that the packet belongs to 1548 * this connection before trimming the data to fit the receive 1549 * window. Check the sequence number versus IRS since we know 1550 * the sequence numbers haven't wrapped. This is a partial fix 1551 * for the "LAND" DoS attack. 1552 */ 1553 if (tp->t_state == TCPS_SYN_RECEIVED && SEQ_LT(th->th_seq, tp->irs)) { 1554 rstreason = BANDLIM_RST_OPENPORT; 1555 goto dropwithreset; 1556 } 1557 1558 todrop = tp->rcv_nxt - th->th_seq; 1559 if (todrop > 0) { 1560 if (thflags & TH_SYN) { 1561 thflags &= ~TH_SYN; 1562 th->th_seq++; 1563 if (th->th_urp > 1) 1564 th->th_urp--; 1565 else 1566 thflags &= ~TH_URG; 1567 todrop--; 1568 } 1569 /* 1570 * Following if statement from Stevens, vol. 2, p. 960. 1571 */ 1572 if (todrop > tlen 1573 || (todrop == tlen && (thflags & TH_FIN) == 0)) { 1574 /* 1575 * Any valid FIN must be to the left of the window. 1576 * At this point the FIN must be a duplicate or out 1577 * of sequence; drop it. 1578 */ 1579 thflags &= ~TH_FIN; 1580 1581 /* 1582 * Send an ACK to resynchronize and drop any data. 1583 * But keep on processing for RST or ACK. 1584 */ 1585 tp->t_flags |= TF_ACKNOW; 1586 todrop = tlen; 1587 tcpstat.tcps_rcvduppack++; 1588 tcpstat.tcps_rcvdupbyte += todrop; 1589 } else { 1590 tcpstat.tcps_rcvpartduppack++; 1591 tcpstat.tcps_rcvpartdupbyte += todrop; 1592 } 1593 drop_hdrlen += todrop; /* drop from the top afterwards */ 1594 th->th_seq += todrop; 1595 tlen -= todrop; 1596 if (th->th_urp > todrop) 1597 th->th_urp -= todrop; 1598 else { 1599 thflags &= ~TH_URG; 1600 th->th_urp = 0; 1601 } 1602 } 1603 1604 /* 1605 * If new data are received on a connection after the 1606 * user processes are gone, then RST the other end. 1607 */ 1608 if ((so->so_state & SS_NOFDREF) && 1609 tp->t_state > TCPS_CLOSE_WAIT && tlen) { 1610 tp = tcp_close(tp); 1611 tcpstat.tcps_rcvafterclose++; 1612 rstreason = BANDLIM_UNLIMITED; 1613 goto dropwithreset; 1614 } 1615 1616 /* 1617 * If segment ends after window, drop trailing data 1618 * (and PUSH and FIN); if nothing left, just ACK. 1619 */ 1620 todrop = (th->th_seq+tlen) - (tp->rcv_nxt+tp->rcv_wnd); 1621 if (todrop > 0) { 1622 tcpstat.tcps_rcvpackafterwin++; 1623 if (todrop >= tlen) { 1624 tcpstat.tcps_rcvbyteafterwin += tlen; 1625 /* 1626 * If a new connection request is received 1627 * while in TIME_WAIT, drop the old connection 1628 * and start over if the sequence numbers 1629 * are above the previous ones. 1630 */ 1631 KASSERT(tp->t_state != TCPS_TIME_WAIT, ("timewait")); 1632 if (thflags & TH_SYN && 1633 tp->t_state == TCPS_TIME_WAIT && 1634 SEQ_GT(th->th_seq, tp->rcv_nxt)) { 1635 tp = tcp_close(tp); 1636 goto findpcb; 1637 } 1638 /* 1639 * If window is closed can only take segments at 1640 * window edge, and have to drop data and PUSH from 1641 * incoming segments. Continue processing, but 1642 * remember to ack. Otherwise, drop segment 1643 * and ack. 1644 */ 1645 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 1646 tp->t_flags |= TF_ACKNOW; 1647 tcpstat.tcps_rcvwinprobe++; 1648 } else 1649 goto dropafterack; 1650 } else 1651 tcpstat.tcps_rcvbyteafterwin += todrop; 1652 m_adj(m, -todrop); 1653 tlen -= todrop; 1654 thflags &= ~(TH_PUSH|TH_FIN); 1655 } 1656 1657 /* 1658 * If last ACK falls within this segment's sequence numbers, 1659 * record its timestamp. 1660 * NOTE that the test is modified according to the latest 1661 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 1662 */ 1663 if ((to.to_flags & TOF_TS) != 0 && 1664 SEQ_LEQ(th->th_seq, tp->last_ack_sent)) { 1665 tp->ts_recent_age = ticks; 1666 tp->ts_recent = to.to_tsval; 1667 } 1668 1669 /* 1670 * If a SYN is in the window, then this is an 1671 * error and we send an RST and drop the connection. 1672 */ 1673 if (thflags & TH_SYN) { 1674 tp = tcp_drop(tp, ECONNRESET); 1675 rstreason = BANDLIM_UNLIMITED; 1676 goto dropwithreset; 1677 } 1678 1679 /* 1680 * If the ACK bit is off: if in SYN-RECEIVED state or SENDSYN 1681 * flag is on (half-synchronized state), then queue data for 1682 * later processing; else drop segment and return. 1683 */ 1684 if ((thflags & TH_ACK) == 0) { 1685 if (tp->t_state == TCPS_SYN_RECEIVED || 1686 (tp->t_flags & TF_NEEDSYN)) 1687 goto step6; 1688 else 1689 goto drop; 1690 } 1691 1692 /* 1693 * Ack processing. 1694 */ 1695 switch (tp->t_state) { 1696 1697 /* 1698 * In SYN_RECEIVED state, the ack ACKs our SYN, so enter 1699 * ESTABLISHED state and continue processing. 1700 * The ACK was checked above. 1701 */ 1702 case TCPS_SYN_RECEIVED: 1703 1704 tcpstat.tcps_connects++; 1705 soisconnected(so); 1706 /* Do window scaling? */ 1707 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 1708 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 1709 tp->snd_scale = tp->requested_s_scale; 1710 tp->rcv_scale = tp->request_r_scale; 1711 } 1712 /* 1713 * Upon successful completion of 3-way handshake, 1714 * update cache.CC if it was undefined, pass any queued 1715 * data to the user, and advance state appropriately. 1716 */ 1717 if ((taop = tcp_gettaocache(&inp->inp_inc)) != NULL && 1718 taop->tao_cc == 0) 1719 taop->tao_cc = tp->cc_recv; 1720 1721 /* 1722 * Make transitions: 1723 * SYN-RECEIVED -> ESTABLISHED 1724 * SYN-RECEIVED* -> FIN-WAIT-1 1725 */ 1726 tp->t_starttime = ticks; 1727 if (tp->t_flags & TF_NEEDFIN) { 1728 tp->t_state = TCPS_FIN_WAIT_1; 1729 tp->t_flags &= ~TF_NEEDFIN; 1730 } else { 1731 tp->t_state = TCPS_ESTABLISHED; 1732 callout_reset(tp->tt_keep, tcp_keepidle, 1733 tcp_timer_keep, tp); 1734 } 1735 /* 1736 * If segment contains data or ACK, will call tcp_reass() 1737 * later; if not, do so now to pass queued data to user. 1738 */ 1739 if (tlen == 0 && (thflags & TH_FIN) == 0) 1740 (void) tcp_reass(tp, (struct tcphdr *)0, 0, 1741 (struct mbuf *)0); 1742 tp->snd_wl1 = th->th_seq - 1; 1743 /* FALLTHROUGH */ 1744 1745 /* 1746 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 1747 * ACKs. If the ack is in the range 1748 * tp->snd_una < th->th_ack <= tp->snd_max 1749 * then advance tp->snd_una to th->th_ack and drop 1750 * data from the retransmission queue. If this ACK reflects 1751 * more up to date window information we update our window information. 1752 */ 1753 case TCPS_ESTABLISHED: 1754 case TCPS_FIN_WAIT_1: 1755 case TCPS_FIN_WAIT_2: 1756 case TCPS_CLOSE_WAIT: 1757 case TCPS_CLOSING: 1758 case TCPS_LAST_ACK: 1759 case TCPS_TIME_WAIT: 1760 KASSERT(tp->t_state != TCPS_TIME_WAIT, ("timewait")); 1761 if (SEQ_LEQ(th->th_ack, tp->snd_una)) { 1762 if (tlen == 0 && tiwin == tp->snd_wnd) { 1763 tcpstat.tcps_rcvdupack++; 1764 /* 1765 * If we have outstanding data (other than 1766 * a window probe), this is a completely 1767 * duplicate ack (ie, window info didn't 1768 * change), the ack is the biggest we've 1769 * seen and we've seen exactly our rexmt 1770 * threshhold of them, assume a packet 1771 * has been dropped and retransmit it. 1772 * Kludge snd_nxt & the congestion 1773 * window so we send only this one 1774 * packet. 1775 * 1776 * We know we're losing at the current 1777 * window size so do congestion avoidance 1778 * (set ssthresh to half the current window 1779 * and pull our congestion window back to 1780 * the new ssthresh). 1781 * 1782 * Dup acks mean that packets have left the 1783 * network (they're now cached at the receiver) 1784 * so bump cwnd by the amount in the receiver 1785 * to keep a constant cwnd packets in the 1786 * network. 1787 */ 1788 if (!callout_active(tp->tt_rexmt) || 1789 th->th_ack != tp->snd_una) 1790 tp->t_dupacks = 0; 1791 else if (++tp->t_dupacks > tcprexmtthresh || 1792 (tcp_do_newreno && 1793 SEQ_LT(tp->snd_una, 1794 tp->snd_recover))) { 1795 tp->snd_cwnd += tp->t_maxseg; 1796 (void) tcp_output(tp); 1797 goto drop; 1798 } else if (tp->t_dupacks == tcprexmtthresh) { 1799 tcp_seq onxt = tp->snd_nxt; 1800 u_int win; 1801 if (tcp_do_newreno && 1802 SEQ_LEQ(th->th_ack, tp->snd_high)) { 1803 tp->t_dupacks = 0; 1804 break; 1805 } 1806 win = min(tp->snd_wnd, tp->snd_cwnd) / 1807 2 / tp->t_maxseg; 1808 if (win < 2) 1809 win = 2; 1810 tp->snd_ssthresh = win * tp->t_maxseg; 1811 tp->snd_recover = tp->snd_max; 1812 callout_stop(tp->tt_rexmt); 1813 tp->t_rtttime = 0; 1814 tp->snd_nxt = th->th_ack; 1815 tp->snd_cwnd = tp->t_maxseg; 1816 (void) tcp_output(tp); 1817 KASSERT(tp->snd_limited <= 2, 1818 ("tp->snd_limited too big")); 1819 tp->snd_cwnd = tp->snd_ssthresh + 1820 tp->t_maxseg * 1821 (tp->t_dupacks - tp->snd_limited); 1822 if (SEQ_GT(onxt, tp->snd_nxt)) 1823 tp->snd_nxt = onxt; 1824 goto drop; 1825 } else if (tcp_do_rfc3042) { 1826 u_long oldcwnd = tp->snd_cwnd; 1827 tcp_seq oldsndmax = tp->snd_max; 1828 u_int sent; 1829 KASSERT(tp->t_dupacks == 1 || 1830 tp->t_dupacks == 2, 1831 ("dupacks not 1 or 2")); 1832 if (tp->t_dupacks == 1) { 1833 tp->snd_limited = 0; 1834 tp->snd_cwnd += tp->t_maxseg; 1835 } else { 1836 tp->snd_cwnd += 1837 tp->t_maxseg * 2; 1838 } 1839 (void) tcp_output(tp); 1840 sent = tp->snd_max - oldsndmax; 1841 if (sent > tp->t_maxseg) { 1842 KASSERT(tp->snd_limited == 0 && 1843 tp->t_dupacks == 2, 1844 ("sent too much")); 1845 tp->snd_limited = 2; 1846 } else if (sent > 0) 1847 ++tp->snd_limited; 1848 tp->snd_cwnd = oldcwnd; 1849 goto drop; 1850 } 1851 } else 1852 tp->t_dupacks = 0; 1853 break; 1854 } 1855 1856 KASSERT(SEQ_GT(th->th_ack, tp->snd_una), ("th_ack <= snd_una")); 1857 1858 /* 1859 * If the congestion window was inflated to account 1860 * for the other side's cached packets, retract it. 1861 */ 1862 if (tcp_do_newreno) { 1863 if (SEQ_LT(tp->snd_una, tp->snd_recover)) { 1864 if (SEQ_LT(th->th_ack, tp->snd_recover)) { 1865 tcp_newreno_partial_ack(tp, th); 1866 } else { 1867 /* 1868 * Window inflation should have left us 1869 * with approximately snd_ssthresh 1870 * outstanding data. 1871 * But in case we would be inclined to 1872 * send a burst, better to do it via 1873 * the slow start mechanism. 1874 */ 1875 if (SEQ_GT(th->th_ack + 1876 tp->snd_ssthresh, 1877 tp->snd_max)) 1878 tp->snd_cwnd = tp->snd_max - 1879 th->th_ack + 1880 tp->t_maxseg; 1881 else 1882 tp->snd_cwnd = tp->snd_ssthresh; 1883 } 1884 } 1885 } else { 1886 if (tp->t_dupacks >= tcprexmtthresh && 1887 tp->snd_cwnd > tp->snd_ssthresh) 1888 tp->snd_cwnd = tp->snd_ssthresh; 1889 } 1890 tp->t_dupacks = 0; 1891 if (SEQ_GT(th->th_ack, tp->snd_max)) { 1892 tcpstat.tcps_rcvacktoomuch++; 1893 goto dropafterack; 1894 } 1895 /* 1896 * If we reach this point, ACK is not a duplicate, 1897 * i.e., it ACKs something we sent. 1898 */ 1899 if (tp->t_flags & TF_NEEDSYN) { 1900 /* 1901 * T/TCP: Connection was half-synchronized, and our 1902 * SYN has been ACK'd (so connection is now fully 1903 * synchronized). Go to non-starred state, 1904 * increment snd_una for ACK of SYN, and check if 1905 * we can do window scaling. 1906 */ 1907 tp->t_flags &= ~TF_NEEDSYN; 1908 tp->snd_una++; 1909 /* Do window scaling? */ 1910 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 1911 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 1912 tp->snd_scale = tp->requested_s_scale; 1913 tp->rcv_scale = tp->request_r_scale; 1914 } 1915 } 1916 1917 process_ACK: 1918 acked = th->th_ack - tp->snd_una; 1919 tcpstat.tcps_rcvackpack++; 1920 tcpstat.tcps_rcvackbyte += acked; 1921 1922 /* 1923 * If we just performed our first retransmit, and the ACK 1924 * arrives within our recovery window, then it was a mistake 1925 * to do the retransmit in the first place. Recover our 1926 * original cwnd and ssthresh, and proceed to transmit where 1927 * we left off. 1928 */ 1929 if (tp->t_rxtshift == 1 && ticks < tp->t_badrxtwin) { 1930 ++tcpstat.tcps_sndrexmitbad; 1931 tp->snd_cwnd = tp->snd_cwnd_prev; 1932 tp->snd_ssthresh = tp->snd_ssthresh_prev; 1933 tp->snd_high = tp->snd_high_prev; 1934 tp->snd_nxt = tp->snd_max; 1935 tp->t_badrxtwin = 0; /* XXX probably not required */ 1936 } 1937 1938 /* 1939 * If we have a timestamp reply, update smoothed 1940 * round trip time. If no timestamp is present but 1941 * transmit timer is running and timed sequence 1942 * number was acked, update smoothed round trip time. 1943 * Since we now have an rtt measurement, cancel the 1944 * timer backoff (cf., Phil Karn's retransmit alg.). 1945 * Recompute the initial retransmit timer. 1946 * 1947 * Some boxes send broken timestamp replies 1948 * during the SYN+ACK phase, ignore 1949 * timestamps of 0 or we could calculate a 1950 * huge RTT and blow up the retransmit timer. 1951 */ 1952 if ((to.to_flags & TOF_TS) != 0 && 1953 to.to_tsecr) { 1954 tcp_xmit_timer(tp, ticks - to.to_tsecr + 1); 1955 } else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) { 1956 tcp_xmit_timer(tp, ticks - tp->t_rtttime); 1957 } 1958 tcp_xmit_bandwidth_limit(tp, th->th_ack); 1959 1960 /* 1961 * If all outstanding data is acked, stop retransmit 1962 * timer and remember to restart (more output or persist). 1963 * If there is more data to be acked, restart retransmit 1964 * timer, using current (possibly backed-off) value. 1965 */ 1966 if (th->th_ack == tp->snd_max) { 1967 callout_stop(tp->tt_rexmt); 1968 needoutput = 1; 1969 } else if (!callout_active(tp->tt_persist)) 1970 callout_reset(tp->tt_rexmt, tp->t_rxtcur, 1971 tcp_timer_rexmt, tp); 1972 1973 /* 1974 * If no data (only SYN) was ACK'd, 1975 * skip rest of ACK processing. 1976 */ 1977 if (acked == 0) 1978 goto step6; 1979 1980 /* 1981 * When new data is acked, open the congestion window. 1982 * If the window gives us less than ssthresh packets 1983 * in flight, open exponentially (maxseg per packet). 1984 * Otherwise open linearly: maxseg per window 1985 * (maxseg^2 / cwnd per packet). 1986 */ 1987 if (!tcp_do_newreno || SEQ_GEQ(tp->snd_una, tp->snd_recover)) { 1988 register u_int cw = tp->snd_cwnd; 1989 register u_int incr = tp->t_maxseg; 1990 if (cw > tp->snd_ssthresh) 1991 incr = incr * incr / cw; 1992 tp->snd_cwnd = min(cw+incr, TCP_MAXWIN<<tp->snd_scale); 1993 } 1994 if (acked > so->so_snd.sb_cc) { 1995 tp->snd_wnd -= so->so_snd.sb_cc; 1996 sbdrop(&so->so_snd, (int)so->so_snd.sb_cc); 1997 ourfinisacked = 1; 1998 } else { 1999 sbdrop(&so->so_snd, acked); 2000 tp->snd_wnd -= acked; 2001 ourfinisacked = 0; 2002 } 2003 sowwakeup(so); 2004 /* detect una wraparound */ 2005 if (SEQ_GEQ(tp->snd_una, tp->snd_recover) && 2006 SEQ_LT(th->th_ack, tp->snd_recover)) 2007 tp->snd_recover = th->th_ack; 2008 if (SEQ_GT(tp->snd_una, tp->snd_high) && 2009 SEQ_LEQ(th->th_ack, tp->snd_high)) 2010 tp->snd_high = th->th_ack - 1; 2011 tp->snd_una = th->th_ack; 2012 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2013 tp->snd_nxt = tp->snd_una; 2014 2015 switch (tp->t_state) { 2016 2017 /* 2018 * In FIN_WAIT_1 STATE in addition to the processing 2019 * for the ESTABLISHED state if our FIN is now acknowledged 2020 * then enter FIN_WAIT_2. 2021 */ 2022 case TCPS_FIN_WAIT_1: 2023 if (ourfinisacked) { 2024 /* 2025 * If we can't receive any more 2026 * data, then closing user can proceed. 2027 * Starting the timer is contrary to the 2028 * specification, but if we don't get a FIN 2029 * we'll hang forever. 2030 */ 2031 /* XXXjl 2032 * we should release the tp also, and use a 2033 * compressed state. 2034 */ 2035 if (so->so_state & SS_CANTRCVMORE) { 2036 soisdisconnected(so); 2037 callout_reset(tp->tt_2msl, tcp_maxidle, 2038 tcp_timer_2msl, tp); 2039 } 2040 tp->t_state = TCPS_FIN_WAIT_2; 2041 } 2042 break; 2043 2044 /* 2045 * In CLOSING STATE in addition to the processing for 2046 * the ESTABLISHED state if the ACK acknowledges our FIN 2047 * then enter the TIME-WAIT state, otherwise ignore 2048 * the segment. 2049 */ 2050 case TCPS_CLOSING: 2051 if (ourfinisacked) { 2052 KASSERT(headlocked, ("headlocked")); 2053 tcp_twstart(tp); 2054 INP_INFO_WUNLOCK(&tcbinfo); 2055 m_freem(m); 2056 return; 2057 } 2058 break; 2059 2060 /* 2061 * In LAST_ACK, we may still be waiting for data to drain 2062 * and/or to be acked, as well as for the ack of our FIN. 2063 * If our FIN is now acknowledged, delete the TCB, 2064 * enter the closed state and return. 2065 */ 2066 case TCPS_LAST_ACK: 2067 if (ourfinisacked) { 2068 tp = tcp_close(tp); 2069 goto drop; 2070 } 2071 break; 2072 2073 /* 2074 * In TIME_WAIT state the only thing that should arrive 2075 * is a retransmission of the remote FIN. Acknowledge 2076 * it and restart the finack timer. 2077 */ 2078 case TCPS_TIME_WAIT: 2079 KASSERT(tp->t_state != TCPS_TIME_WAIT, ("timewait")); 2080 callout_reset(tp->tt_2msl, 2 * tcp_msl, 2081 tcp_timer_2msl, tp); 2082 goto dropafterack; 2083 } 2084 } 2085 2086 step6: 2087 /* 2088 * Update window information. 2089 * Don't look at window if no ACK: TAC's send garbage on first SYN. 2090 */ 2091 if ((thflags & TH_ACK) && 2092 (SEQ_LT(tp->snd_wl1, th->th_seq) || 2093 (tp->snd_wl1 == th->th_seq && (SEQ_LT(tp->snd_wl2, th->th_ack) || 2094 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))) { 2095 /* keep track of pure window updates */ 2096 if (tlen == 0 && 2097 tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) 2098 tcpstat.tcps_rcvwinupd++; 2099 tp->snd_wnd = tiwin; 2100 tp->snd_wl1 = th->th_seq; 2101 tp->snd_wl2 = th->th_ack; 2102 if (tp->snd_wnd > tp->max_sndwnd) 2103 tp->max_sndwnd = tp->snd_wnd; 2104 needoutput = 1; 2105 } 2106 2107 /* 2108 * Process segments with URG. 2109 */ 2110 if ((thflags & TH_URG) && th->th_urp && 2111 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2112 /* 2113 * This is a kludge, but if we receive and accept 2114 * random urgent pointers, we'll crash in 2115 * soreceive. It's hard to imagine someone 2116 * actually wanting to send this much urgent data. 2117 */ 2118 if (th->th_urp + so->so_rcv.sb_cc > sb_max) { 2119 th->th_urp = 0; /* XXX */ 2120 thflags &= ~TH_URG; /* XXX */ 2121 goto dodata; /* XXX */ 2122 } 2123 /* 2124 * If this segment advances the known urgent pointer, 2125 * then mark the data stream. This should not happen 2126 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 2127 * a FIN has been received from the remote side. 2128 * In these states we ignore the URG. 2129 * 2130 * According to RFC961 (Assigned Protocols), 2131 * the urgent pointer points to the last octet 2132 * of urgent data. We continue, however, 2133 * to consider it to indicate the first octet 2134 * of data past the urgent section as the original 2135 * spec states (in one of two places). 2136 */ 2137 if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) { 2138 tp->rcv_up = th->th_seq + th->th_urp; 2139 so->so_oobmark = so->so_rcv.sb_cc + 2140 (tp->rcv_up - tp->rcv_nxt) - 1; 2141 if (so->so_oobmark == 0) 2142 so->so_state |= SS_RCVATMARK; 2143 sohasoutofband(so); 2144 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); 2145 } 2146 /* 2147 * Remove out of band data so doesn't get presented to user. 2148 * This can happen independent of advancing the URG pointer, 2149 * but if two URG's are pending at once, some out-of-band 2150 * data may creep in... ick. 2151 */ 2152 if (th->th_urp <= (u_long)tlen && 2153 !(so->so_options & SO_OOBINLINE)) { 2154 /* hdr drop is delayed */ 2155 tcp_pulloutofband(so, th, m, drop_hdrlen); 2156 } 2157 } else { 2158 /* 2159 * If no out of band data is expected, 2160 * pull receive urgent pointer along 2161 * with the receive window. 2162 */ 2163 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) 2164 tp->rcv_up = tp->rcv_nxt; 2165 } 2166 dodata: /* XXX */ 2167 KASSERT(headlocked, ("headlocked")); 2168 /* 2169 * Process the segment text, merging it into the TCP sequencing queue, 2170 * and arranging for acknowledgment of receipt if necessary. 2171 * This process logically involves adjusting tp->rcv_wnd as data 2172 * is presented to the user (this happens in tcp_usrreq.c, 2173 * case PRU_RCVD). If a FIN has already been received on this 2174 * connection then we just ignore the text. 2175 */ 2176 if ((tlen || (thflags & TH_FIN)) && 2177 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2178 m_adj(m, drop_hdrlen); /* delayed header drop */ 2179 /* 2180 * Insert segment which includes th into TCP reassembly queue 2181 * with control block tp. Set thflags to whether reassembly now 2182 * includes a segment with FIN. This handles the common case 2183 * inline (segment is the next to be received on an established 2184 * connection, and the queue is empty), avoiding linkage into 2185 * and removal from the queue and repetition of various 2186 * conversions. 2187 * Set DELACK for segments received in order, but ack 2188 * immediately when segments are out of order (so 2189 * fast retransmit can work). 2190 */ 2191 if (th->th_seq == tp->rcv_nxt && 2192 LIST_EMPTY(&tp->t_segq) && 2193 TCPS_HAVEESTABLISHED(tp->t_state)) { 2194 if (DELAY_ACK(tp)) 2195 tp->t_flags |= TF_DELACK; 2196 else 2197 tp->t_flags |= TF_ACKNOW; 2198 tp->rcv_nxt += tlen; 2199 thflags = th->th_flags & TH_FIN; 2200 tcpstat.tcps_rcvpack++; 2201 tcpstat.tcps_rcvbyte += tlen; 2202 ND6_HINT(tp); 2203 if (so->so_state & SS_CANTRCVMORE) 2204 m_freem(m); 2205 else 2206 sbappend(&so->so_rcv, m); 2207 sorwakeup(so); 2208 } else { 2209 thflags = tcp_reass(tp, th, &tlen, m); 2210 tp->t_flags |= TF_ACKNOW; 2211 } 2212 2213 /* 2214 * Note the amount of data that peer has sent into 2215 * our window, in order to estimate the sender's 2216 * buffer size. 2217 */ 2218 len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); 2219 } else { 2220 m_freem(m); 2221 thflags &= ~TH_FIN; 2222 } 2223 2224 /* 2225 * If FIN is received ACK the FIN and let the user know 2226 * that the connection is closing. 2227 */ 2228 if (thflags & TH_FIN) { 2229 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2230 socantrcvmore(so); 2231 /* 2232 * If connection is half-synchronized 2233 * (ie NEEDSYN flag on) then delay ACK, 2234 * so it may be piggybacked when SYN is sent. 2235 * Otherwise, since we received a FIN then no 2236 * more input can be expected, send ACK now. 2237 */ 2238 if (tp->t_flags & TF_NEEDSYN) 2239 tp->t_flags |= TF_DELACK; 2240 else 2241 tp->t_flags |= TF_ACKNOW; 2242 tp->rcv_nxt++; 2243 } 2244 switch (tp->t_state) { 2245 2246 /* 2247 * In SYN_RECEIVED and ESTABLISHED STATES 2248 * enter the CLOSE_WAIT state. 2249 */ 2250 case TCPS_SYN_RECEIVED: 2251 tp->t_starttime = ticks; 2252 /*FALLTHROUGH*/ 2253 case TCPS_ESTABLISHED: 2254 tp->t_state = TCPS_CLOSE_WAIT; 2255 break; 2256 2257 /* 2258 * If still in FIN_WAIT_1 STATE FIN has not been acked so 2259 * enter the CLOSING state. 2260 */ 2261 case TCPS_FIN_WAIT_1: 2262 tp->t_state = TCPS_CLOSING; 2263 break; 2264 2265 /* 2266 * In FIN_WAIT_2 state enter the TIME_WAIT state, 2267 * starting the time-wait timer, turning off the other 2268 * standard timers. 2269 */ 2270 case TCPS_FIN_WAIT_2: 2271 KASSERT(headlocked == 1, ("headlocked should be 1")); 2272 tcp_twstart(tp); 2273 INP_INFO_WUNLOCK(&tcbinfo); 2274 return; 2275 2276 /* 2277 * In TIME_WAIT state restart the 2 MSL time_wait timer. 2278 */ 2279 case TCPS_TIME_WAIT: 2280 KASSERT(tp->t_state != TCPS_TIME_WAIT, ("timewait")); 2281 callout_reset(tp->tt_2msl, 2 * tcp_msl, 2282 tcp_timer_2msl, tp); 2283 break; 2284 } 2285 } 2286 INP_INFO_WUNLOCK(&tcbinfo); 2287 #ifdef TCPDEBUG 2288 if (so->so_options & SO_DEBUG) 2289 tcp_trace(TA_INPUT, ostate, tp, (void *)tcp_saveipgen, 2290 &tcp_savetcp, 0); 2291 #endif 2292 2293 /* 2294 * Return any desired output. 2295 */ 2296 if (needoutput || (tp->t_flags & TF_ACKNOW)) 2297 (void) tcp_output(tp); 2298 2299 check_delack: 2300 if (tp->t_flags & TF_DELACK) { 2301 tp->t_flags &= ~TF_DELACK; 2302 callout_reset(tp->tt_delack, tcp_delacktime, 2303 tcp_timer_delack, tp); 2304 } 2305 INP_UNLOCK(inp); 2306 return; 2307 2308 dropafterack: 2309 /* 2310 * Generate an ACK dropping incoming segment if it occupies 2311 * sequence space, where the ACK reflects our state. 2312 * 2313 * We can now skip the test for the RST flag since all 2314 * paths to this code happen after packets containing 2315 * RST have been dropped. 2316 * 2317 * In the SYN-RECEIVED state, don't send an ACK unless the 2318 * segment we received passes the SYN-RECEIVED ACK test. 2319 * If it fails send a RST. This breaks the loop in the 2320 * "LAND" DoS attack, and also prevents an ACK storm 2321 * between two listening ports that have been sent forged 2322 * SYN segments, each with the source address of the other. 2323 */ 2324 if (tp->t_state == TCPS_SYN_RECEIVED && (thflags & TH_ACK) && 2325 (SEQ_GT(tp->snd_una, th->th_ack) || 2326 SEQ_GT(th->th_ack, tp->snd_max)) ) { 2327 rstreason = BANDLIM_RST_OPENPORT; 2328 goto dropwithreset; 2329 } 2330 #ifdef TCPDEBUG 2331 if (so->so_options & SO_DEBUG) 2332 tcp_trace(TA_DROP, ostate, tp, (void *)tcp_saveipgen, 2333 &tcp_savetcp, 0); 2334 #endif 2335 KASSERT(headlocked, ("headlocked should be 1")); 2336 INP_INFO_WUNLOCK(&tcbinfo); 2337 m_freem(m); 2338 tp->t_flags |= TF_ACKNOW; 2339 (void) tcp_output(tp); 2340 INP_UNLOCK(inp); 2341 return; 2342 2343 dropwithreset: 2344 /* 2345 * Generate a RST, dropping incoming segment. 2346 * Make ACK acceptable to originator of segment. 2347 * Don't bother to respond if destination was broadcast/multicast. 2348 */ 2349 if ((thflags & TH_RST) || m->m_flags & (M_BCAST|M_MCAST)) 2350 goto drop; 2351 if (isipv6) { 2352 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 2353 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) 2354 goto drop; 2355 } else { 2356 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || 2357 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 2358 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || 2359 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 2360 goto drop; 2361 } 2362 /* IPv6 anycast check is done at tcp6_input() */ 2363 2364 /* 2365 * Perform bandwidth limiting. 2366 */ 2367 if (badport_bandlim(rstreason) < 0) 2368 goto drop; 2369 2370 #ifdef TCPDEBUG 2371 if (tp == 0 || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 2372 tcp_trace(TA_DROP, ostate, tp, (void *)tcp_saveipgen, 2373 &tcp_savetcp, 0); 2374 #endif 2375 2376 if (tp) 2377 INP_UNLOCK(inp); 2378 2379 if (thflags & TH_ACK) 2380 /* mtod() below is safe as long as hdr dropping is delayed */ 2381 tcp_respond(tp, mtod(m, void *), th, m, (tcp_seq)0, th->th_ack, 2382 TH_RST); 2383 else { 2384 if (thflags & TH_SYN) 2385 tlen++; 2386 /* mtod() below is safe as long as hdr dropping is delayed */ 2387 tcp_respond(tp, mtod(m, void *), th, m, th->th_seq+tlen, 2388 (tcp_seq)0, TH_RST|TH_ACK); 2389 } 2390 if (headlocked) 2391 INP_INFO_WUNLOCK(&tcbinfo); 2392 return; 2393 2394 drop: 2395 /* 2396 * Drop space held by incoming segment and return. 2397 */ 2398 #ifdef TCPDEBUG 2399 if (tp == 0 || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 2400 tcp_trace(TA_DROP, ostate, tp, (void *)tcp_saveipgen, 2401 &tcp_savetcp, 0); 2402 #endif 2403 if (tp) 2404 INP_UNLOCK(inp); 2405 m_freem(m); 2406 if (headlocked) 2407 INP_INFO_WUNLOCK(&tcbinfo); 2408 return; 2409 } 2410 2411 /* 2412 * Parse TCP options and place in tcpopt. 2413 */ 2414 static void 2415 tcp_dooptions(to, cp, cnt, is_syn) 2416 struct tcpopt *to; 2417 u_char *cp; 2418 int cnt; 2419 int is_syn; 2420 { 2421 int opt, optlen; 2422 2423 to->to_flags = 0; 2424 for (; cnt > 0; cnt -= optlen, cp += optlen) { 2425 opt = cp[0]; 2426 if (opt == TCPOPT_EOL) 2427 break; 2428 if (opt == TCPOPT_NOP) 2429 optlen = 1; 2430 else { 2431 if (cnt < 2) 2432 break; 2433 optlen = cp[1]; 2434 if (optlen < 2 || optlen > cnt) 2435 break; 2436 } 2437 switch (opt) { 2438 case TCPOPT_MAXSEG: 2439 if (optlen != TCPOLEN_MAXSEG) 2440 continue; 2441 if (!is_syn) 2442 continue; 2443 to->to_flags |= TOF_MSS; 2444 bcopy((char *)cp + 2, 2445 (char *)&to->to_mss, sizeof(to->to_mss)); 2446 to->to_mss = ntohs(to->to_mss); 2447 break; 2448 case TCPOPT_WINDOW: 2449 if (optlen != TCPOLEN_WINDOW) 2450 continue; 2451 if (! is_syn) 2452 continue; 2453 to->to_flags |= TOF_SCALE; 2454 to->to_requested_s_scale = min(cp[2], TCP_MAX_WINSHIFT); 2455 break; 2456 case TCPOPT_TIMESTAMP: 2457 if (optlen != TCPOLEN_TIMESTAMP) 2458 continue; 2459 to->to_flags |= TOF_TS; 2460 bcopy((char *)cp + 2, 2461 (char *)&to->to_tsval, sizeof(to->to_tsval)); 2462 to->to_tsval = ntohl(to->to_tsval); 2463 bcopy((char *)cp + 6, 2464 (char *)&to->to_tsecr, sizeof(to->to_tsecr)); 2465 to->to_tsecr = ntohl(to->to_tsecr); 2466 break; 2467 case TCPOPT_CC: 2468 if (optlen != TCPOLEN_CC) 2469 continue; 2470 to->to_flags |= TOF_CC; 2471 bcopy((char *)cp + 2, 2472 (char *)&to->to_cc, sizeof(to->to_cc)); 2473 to->to_cc = ntohl(to->to_cc); 2474 break; 2475 case TCPOPT_CCNEW: 2476 if (optlen != TCPOLEN_CC) 2477 continue; 2478 if (!is_syn) 2479 continue; 2480 to->to_flags |= TOF_CCNEW; 2481 bcopy((char *)cp + 2, 2482 (char *)&to->to_cc, sizeof(to->to_cc)); 2483 to->to_cc = ntohl(to->to_cc); 2484 break; 2485 case TCPOPT_CCECHO: 2486 if (optlen != TCPOLEN_CC) 2487 continue; 2488 if (!is_syn) 2489 continue; 2490 to->to_flags |= TOF_CCECHO; 2491 bcopy((char *)cp + 2, 2492 (char *)&to->to_ccecho, sizeof(to->to_ccecho)); 2493 to->to_ccecho = ntohl(to->to_ccecho); 2494 break; 2495 default: 2496 continue; 2497 } 2498 } 2499 } 2500 2501 /* 2502 * Pull out of band byte out of a segment so 2503 * it doesn't appear in the user's data queue. 2504 * It is still reflected in the segment length for 2505 * sequencing purposes. 2506 */ 2507 static void 2508 tcp_pulloutofband(so, th, m, off) 2509 struct socket *so; 2510 struct tcphdr *th; 2511 register struct mbuf *m; 2512 int off; /* delayed to be droped hdrlen */ 2513 { 2514 int cnt = off + th->th_urp - 1; 2515 2516 while (cnt >= 0) { 2517 if (m->m_len > cnt) { 2518 char *cp = mtod(m, caddr_t) + cnt; 2519 struct tcpcb *tp = sototcpcb(so); 2520 2521 tp->t_iobc = *cp; 2522 tp->t_oobflags |= TCPOOB_HAVEDATA; 2523 bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); 2524 m->m_len--; 2525 if (m->m_flags & M_PKTHDR) 2526 m->m_pkthdr.len--; 2527 return; 2528 } 2529 cnt -= m->m_len; 2530 m = m->m_next; 2531 if (m == 0) 2532 break; 2533 } 2534 panic("tcp_pulloutofband"); 2535 } 2536 2537 /* 2538 * Collect new round-trip time estimate 2539 * and update averages and current timeout. 2540 */ 2541 static void 2542 tcp_xmit_timer(tp, rtt) 2543 register struct tcpcb *tp; 2544 int rtt; 2545 { 2546 register int delta; 2547 2548 tcpstat.tcps_rttupdated++; 2549 tp->t_rttupdated++; 2550 if (tp->t_srtt != 0) { 2551 /* 2552 * srtt is stored as fixed point with 5 bits after the 2553 * binary point (i.e., scaled by 8). The following magic 2554 * is equivalent to the smoothing algorithm in rfc793 with 2555 * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed 2556 * point). Adjust rtt to origin 0. 2557 */ 2558 delta = ((rtt - 1) << TCP_DELTA_SHIFT) 2559 - (tp->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT)); 2560 2561 if ((tp->t_srtt += delta) <= 0) 2562 tp->t_srtt = 1; 2563 2564 /* 2565 * We accumulate a smoothed rtt variance (actually, a 2566 * smoothed mean difference), then set the retransmit 2567 * timer to smoothed rtt + 4 times the smoothed variance. 2568 * rttvar is stored as fixed point with 4 bits after the 2569 * binary point (scaled by 16). The following is 2570 * equivalent to rfc793 smoothing with an alpha of .75 2571 * (rttvar = rttvar*3/4 + |delta| / 4). This replaces 2572 * rfc793's wired-in beta. 2573 */ 2574 if (delta < 0) 2575 delta = -delta; 2576 delta -= tp->t_rttvar >> (TCP_RTTVAR_SHIFT - TCP_DELTA_SHIFT); 2577 if ((tp->t_rttvar += delta) <= 0) 2578 tp->t_rttvar = 1; 2579 if (tp->t_rttbest > tp->t_srtt + tp->t_rttvar) 2580 tp->t_rttbest = tp->t_srtt + tp->t_rttvar; 2581 } else { 2582 /* 2583 * No rtt measurement yet - use the unsmoothed rtt. 2584 * Set the variance to half the rtt (so our first 2585 * retransmit happens at 3*rtt). 2586 */ 2587 tp->t_srtt = rtt << TCP_RTT_SHIFT; 2588 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1); 2589 tp->t_rttbest = tp->t_srtt + tp->t_rttvar; 2590 } 2591 tp->t_rtttime = 0; 2592 tp->t_rxtshift = 0; 2593 2594 /* 2595 * the retransmit should happen at rtt + 4 * rttvar. 2596 * Because of the way we do the smoothing, srtt and rttvar 2597 * will each average +1/2 tick of bias. When we compute 2598 * the retransmit timer, we want 1/2 tick of rounding and 2599 * 1 extra tick because of +-1/2 tick uncertainty in the 2600 * firing of the timer. The bias will give us exactly the 2601 * 1.5 tick we need. But, because the bias is 2602 * statistical, we have to test that we don't drop below 2603 * the minimum feasible timer (which is 2 ticks). 2604 */ 2605 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), 2606 max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX); 2607 2608 /* 2609 * We received an ack for a packet that wasn't retransmitted; 2610 * it is probably safe to discard any error indications we've 2611 * received recently. This isn't quite right, but close enough 2612 * for now (a route might have failed after we sent a segment, 2613 * and the return path might not be symmetrical). 2614 */ 2615 tp->t_softerror = 0; 2616 } 2617 2618 /* 2619 * Determine a reasonable value for maxseg size. 2620 * If the route is known, check route for mtu. 2621 * If none, use an mss that can be handled on the outgoing 2622 * interface without forcing IP to fragment; if bigger than 2623 * an mbuf cluster (MCLBYTES), round down to nearest multiple of MCLBYTES 2624 * to utilize large mbufs. If no route is found, route has no mtu, 2625 * or the destination isn't local, use a default, hopefully conservative 2626 * size (usually 512 or the default IP max size, but no more than the mtu 2627 * of the interface), as we can't discover anything about intervening 2628 * gateways or networks. We also initialize the congestion/slow start 2629 * window to be a single segment if the destination isn't local. 2630 * While looking at the routing entry, we also initialize other path-dependent 2631 * parameters from pre-set or cached values in the routing entry. 2632 * 2633 * Also take into account the space needed for options that we 2634 * send regularly. Make maxseg shorter by that amount to assure 2635 * that we can send maxseg amount of data even when the options 2636 * are present. Store the upper limit of the length of options plus 2637 * data in maxopd. 2638 * 2639 * NOTE that this routine is only called when we process an incoming 2640 * segment, for outgoing segments only tcp_mssopt is called. 2641 * 2642 * In case of T/TCP, we call this routine during implicit connection 2643 * setup as well (offer = -1), to initialize maxseg from the cached 2644 * MSS of our peer. 2645 */ 2646 void 2647 tcp_mss(tp, offer) 2648 struct tcpcb *tp; 2649 int offer; 2650 { 2651 register struct rtentry *rt; 2652 struct ifnet *ifp; 2653 register int rtt, mss; 2654 u_long bufsize; 2655 struct inpcb *inp = tp->t_inpcb; 2656 struct socket *so; 2657 struct rmxp_tao *taop; 2658 int origoffer = offer; 2659 #ifdef INET6 2660 int isipv6 = ((inp->inp_vflag & INP_IPV6) != 0) ? 1 : 0; 2661 size_t min_protoh = isipv6 ? 2662 sizeof (struct ip6_hdr) + sizeof (struct tcphdr) : 2663 sizeof (struct tcpiphdr); 2664 #else 2665 const int isipv6 = 0; 2666 const size_t min_protoh = sizeof (struct tcpiphdr); 2667 #endif 2668 2669 if (isipv6) 2670 rt = tcp_rtlookup6(&inp->inp_inc); 2671 else 2672 rt = tcp_rtlookup(&inp->inp_inc); 2673 if (rt == NULL) { 2674 tp->t_maxopd = tp->t_maxseg = 2675 isipv6 ? tcp_v6mssdflt : tcp_mssdflt; 2676 return; 2677 } 2678 ifp = rt->rt_ifp; 2679 so = inp->inp_socket; 2680 2681 taop = rmx_taop(rt->rt_rmx); 2682 /* 2683 * Offer == -1 means that we didn't receive SYN yet, 2684 * use cached value in that case; 2685 */ 2686 if (offer == -1) 2687 offer = taop->tao_mssopt; 2688 /* 2689 * Offer == 0 means that there was no MSS on the SYN segment, 2690 * in this case we use tcp_mssdflt. 2691 */ 2692 if (offer == 0) 2693 offer = isipv6 ? tcp_v6mssdflt : tcp_mssdflt; 2694 else 2695 /* 2696 * Sanity check: make sure that maxopd will be large 2697 * enough to allow some data on segments even is the 2698 * all the option space is used (40bytes). Otherwise 2699 * funny things may happen in tcp_output. 2700 */ 2701 offer = max(offer, 64); 2702 taop->tao_mssopt = offer; 2703 2704 /* 2705 * While we're here, check if there's an initial rtt 2706 * or rttvar. Convert from the route-table units 2707 * to scaled multiples of the slow timeout timer. 2708 */ 2709 if (tp->t_srtt == 0 && (rtt = rt->rt_rmx.rmx_rtt)) { 2710 /* 2711 * XXX the lock bit for RTT indicates that the value 2712 * is also a minimum value; this is subject to time. 2713 */ 2714 if (rt->rt_rmx.rmx_locks & RTV_RTT) 2715 tp->t_rttmin = rtt / (RTM_RTTUNIT / hz); 2716 tp->t_srtt = rtt / (RTM_RTTUNIT / (hz * TCP_RTT_SCALE)); 2717 tp->t_rttbest = tp->t_srtt + TCP_RTT_SCALE; 2718 tcpstat.tcps_usedrtt++; 2719 if (rt->rt_rmx.rmx_rttvar) { 2720 tp->t_rttvar = rt->rt_rmx.rmx_rttvar / 2721 (RTM_RTTUNIT / (hz * TCP_RTTVAR_SCALE)); 2722 tcpstat.tcps_usedrttvar++; 2723 } else { 2724 /* default variation is +- 1 rtt */ 2725 tp->t_rttvar = 2726 tp->t_srtt * TCP_RTTVAR_SCALE / TCP_RTT_SCALE; 2727 } 2728 TCPT_RANGESET(tp->t_rxtcur, 2729 ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1, 2730 tp->t_rttmin, TCPTV_REXMTMAX); 2731 } 2732 /* 2733 * if there's an mtu associated with the route, use it 2734 * else, use the link mtu. 2735 */ 2736 if (rt->rt_rmx.rmx_mtu) 2737 mss = rt->rt_rmx.rmx_mtu - min_protoh; 2738 else { 2739 if (isipv6) { 2740 mss = nd_ifinfo[rt->rt_ifp->if_index].linkmtu - 2741 min_protoh; 2742 if (!in6_localaddr(&inp->in6p_faddr)) 2743 mss = min(mss, tcp_v6mssdflt); 2744 } else { 2745 mss = ifp->if_mtu - min_protoh; 2746 if (!in_localaddr(inp->inp_faddr)) 2747 mss = min(mss, tcp_mssdflt); 2748 } 2749 } 2750 mss = min(mss, offer); 2751 /* 2752 * maxopd stores the maximum length of data AND options 2753 * in a segment; maxseg is the amount of data in a normal 2754 * segment. We need to store this value (maxopd) apart 2755 * from maxseg, because now every segment carries options 2756 * and thus we normally have somewhat less data in segments. 2757 */ 2758 tp->t_maxopd = mss; 2759 2760 /* 2761 * In case of T/TCP, origoffer==-1 indicates, that no segments 2762 * were received yet. In this case we just guess, otherwise 2763 * we do the same as before T/TCP. 2764 */ 2765 if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP && 2766 (origoffer == -1 || 2767 (tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP)) 2768 mss -= TCPOLEN_TSTAMP_APPA; 2769 if ((tp->t_flags & (TF_REQ_CC|TF_NOOPT)) == TF_REQ_CC && 2770 (origoffer == -1 || 2771 (tp->t_flags & TF_RCVD_CC) == TF_RCVD_CC)) 2772 mss -= TCPOLEN_CC_APPA; 2773 2774 #if (MCLBYTES & (MCLBYTES - 1)) == 0 2775 if (mss > MCLBYTES) 2776 mss &= ~(MCLBYTES-1); 2777 #else 2778 if (mss > MCLBYTES) 2779 mss = mss / MCLBYTES * MCLBYTES; 2780 #endif 2781 /* 2782 * If there's a pipesize, change the socket buffer 2783 * to that size. Make the socket buffers an integral 2784 * number of mss units; if the mss is larger than 2785 * the socket buffer, decrease the mss. 2786 */ 2787 #ifdef RTV_SPIPE 2788 if ((bufsize = rt->rt_rmx.rmx_sendpipe) == 0) 2789 #endif 2790 bufsize = so->so_snd.sb_hiwat; 2791 if (bufsize < mss) 2792 mss = bufsize; 2793 else { 2794 bufsize = roundup(bufsize, mss); 2795 if (bufsize > sb_max) 2796 bufsize = sb_max; 2797 if (bufsize > so->so_snd.sb_hiwat) 2798 (void)sbreserve(&so->so_snd, bufsize, so, NULL); 2799 } 2800 tp->t_maxseg = mss; 2801 2802 #ifdef RTV_RPIPE 2803 if ((bufsize = rt->rt_rmx.rmx_recvpipe) == 0) 2804 #endif 2805 bufsize = so->so_rcv.sb_hiwat; 2806 if (bufsize > mss) { 2807 bufsize = roundup(bufsize, mss); 2808 if (bufsize > sb_max) 2809 bufsize = sb_max; 2810 if (bufsize > so->so_rcv.sb_hiwat) 2811 (void)sbreserve(&so->so_rcv, bufsize, so, NULL); 2812 } 2813 2814 /* 2815 * Set the slow-start flight size depending on whether this 2816 * is a local network or not. 2817 */ 2818 if (tcp_do_rfc3390) 2819 tp->snd_cwnd = min(4 * mss, max(2 * mss, 4380)); 2820 else if ((isipv6 && in6_localaddr(&inp->in6p_faddr)) || 2821 (!isipv6 && in_localaddr(inp->inp_faddr))) 2822 tp->snd_cwnd = mss * ss_fltsz_local; 2823 else 2824 tp->snd_cwnd = mss * ss_fltsz; 2825 2826 if (rt->rt_rmx.rmx_ssthresh) { 2827 /* 2828 * There's some sort of gateway or interface 2829 * buffer limit on the path. Use this to set 2830 * the slow start threshhold, but set the 2831 * threshold to no less than 2*mss. 2832 */ 2833 tp->snd_ssthresh = max(2 * mss, rt->rt_rmx.rmx_ssthresh); 2834 tcpstat.tcps_usedssthresh++; 2835 } 2836 } 2837 2838 /* 2839 * Determine the MSS option to send on an outgoing SYN. 2840 */ 2841 int 2842 tcp_mssopt(tp) 2843 struct tcpcb *tp; 2844 { 2845 struct rtentry *rt; 2846 #ifdef INET6 2847 int isipv6 = ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) ? 1 : 0; 2848 size_t min_protoh = isipv6 ? 2849 sizeof (struct ip6_hdr) + sizeof (struct tcphdr) : 2850 sizeof (struct tcpiphdr); 2851 #else 2852 const int isipv6 = 0; 2853 const size_t min_protoh = sizeof (struct tcpiphdr); 2854 #endif 2855 2856 if (isipv6) 2857 rt = tcp_rtlookup6(&tp->t_inpcb->inp_inc); 2858 else 2859 rt = tcp_rtlookup(&tp->t_inpcb->inp_inc); 2860 if (rt == NULL) 2861 return (isipv6 ? tcp_v6mssdflt : tcp_mssdflt); 2862 2863 return (rt->rt_ifp->if_mtu - min_protoh); 2864 } 2865 2866 2867 /* 2868 * On a partial ack arrives, force the retransmission of the 2869 * next unacknowledged segment. Do not clear tp->t_dupacks. 2870 * By setting snd_nxt to ti_ack, this forces retransmission timer to 2871 * be started again. 2872 */ 2873 static void 2874 tcp_newreno_partial_ack(tp, th) 2875 struct tcpcb *tp; 2876 struct tcphdr *th; 2877 { 2878 tcp_seq onxt = tp->snd_nxt; 2879 u_long ocwnd = tp->snd_cwnd; 2880 2881 callout_stop(tp->tt_rexmt); 2882 tp->t_rtttime = 0; 2883 tp->snd_nxt = th->th_ack; 2884 /* 2885 * Set snd_cwnd to one segment beyond acknowledged offset. 2886 * (tp->snd_una has not yet been updated when this function is called.) 2887 */ 2888 tp->snd_cwnd = tp->t_maxseg + (th->th_ack - tp->snd_una); 2889 tp->t_flags |= TF_ACKNOW; 2890 (void) tcp_output(tp); 2891 tp->snd_cwnd = ocwnd; 2892 if (SEQ_GT(onxt, tp->snd_nxt)) 2893 tp->snd_nxt = onxt; 2894 /* 2895 * Partial window deflation. Relies on fact that tp->snd_una 2896 * not updated yet. 2897 */ 2898 tp->snd_cwnd -= (th->th_ack - tp->snd_una - tp->t_maxseg); 2899 } 2900 2901 /* 2902 * Returns 1 if the TIME_WAIT state was killed and we should start over, 2903 * looking for a pcb in the listen state. Returns 0 otherwise. 2904 */ 2905 static int 2906 tcp_timewait(tw, to, th, m, tlen) 2907 struct tcptw *tw; 2908 struct tcpopt *to; 2909 struct tcphdr *th; 2910 struct mbuf *m; 2911 int tlen; 2912 { 2913 int thflags; 2914 tcp_seq seq; 2915 #ifdef INET6 2916 int isipv6 = (mtod(m, struct ip *)->ip_v == 6) ? 1 : 0; 2917 #else 2918 const int isipv6 = 0; 2919 #endif 2920 2921 thflags = th->th_flags; 2922 2923 /* 2924 * NOTE: for FIN_WAIT_2 (to be added later), 2925 * must validate sequence number before accepting RST 2926 */ 2927 2928 /* 2929 * If the segment contains RST: 2930 * Drop the segment - see Stevens, vol. 2, p. 964 and 2931 * RFC 1337. 2932 */ 2933 if (thflags & TH_RST) 2934 goto drop; 2935 2936 /* 2937 * If segment contains a SYN and CC [not CC.NEW] option: 2938 * if connection duration > MSL, drop packet and send RST; 2939 * 2940 * if SEG.CC > CCrecv then is new SYN. 2941 * Complete close and delete TCPCB. Then reprocess 2942 * segment, hoping to find new TCPCB in LISTEN state; 2943 * 2944 * else must be old SYN; drop it. 2945 * else do normal processing. 2946 */ 2947 if ((thflags & TH_SYN) && (to->to_flags & TOF_CC) && tw->cc_recv != 0) { 2948 if ((ticks - tw->t_starttime) > tcp_msl) 2949 goto reset; 2950 if (CC_GT(to->to_cc, tw->cc_recv)) { 2951 (void) tcp_twclose(tw, 0); 2952 return (1); 2953 } 2954 goto drop; 2955 } 2956 2957 #if 0 2958 /* PAWS not needed at the moment */ 2959 /* 2960 * RFC 1323 PAWS: If we have a timestamp reply on this segment 2961 * and it's less than ts_recent, drop it. 2962 */ 2963 if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent && 2964 TSTMP_LT(to.to_tsval, tp->ts_recent)) { 2965 if ((thflags & TH_ACK) == 0) 2966 goto drop; 2967 goto ack; 2968 } 2969 /* 2970 * ts_recent is never updated because we never accept new segments. 2971 */ 2972 #endif 2973 2974 /* 2975 * If a new connection request is received 2976 * while in TIME_WAIT, drop the old connection 2977 * and start over if the sequence numbers 2978 * are above the previous ones. 2979 */ 2980 if ((thflags & TH_SYN) && SEQ_GT(th->th_seq, tw->rcv_nxt)) { 2981 (void) tcp_twclose(tw, 0); 2982 return (1); 2983 } 2984 2985 /* 2986 * Drop the the segment if it does not contain an ACK. 2987 */ 2988 if ((thflags & TH_ACK) == 0) 2989 goto drop; 2990 2991 /* 2992 * Reset the 2MSL timer if this is a duplicate FIN. 2993 */ 2994 if (thflags & TH_FIN) { 2995 seq = th->th_seq + tlen + (thflags & TH_SYN ? 1 : 0); 2996 if (seq + 1 == tw->rcv_nxt) 2997 tcp_timer_2msl_reset(tw, 2 * tcp_msl); 2998 } 2999 3000 /* 3001 * Acknowledge the segment if it has data or is not a duplicate ACK. 3002 */ 3003 if (thflags != TH_ACK || tlen != 0 || 3004 th->th_seq != tw->rcv_nxt || th->th_ack != tw->snd_nxt) 3005 tcp_twrespond(tw, NULL, m, TH_ACK); 3006 goto drop; 3007 3008 reset: 3009 /* 3010 * Generate a RST, dropping incoming segment. 3011 * Make ACK acceptable to originator of segment. 3012 * Don't bother to respond if destination was broadcast/multicast. 3013 */ 3014 if (m->m_flags & (M_BCAST|M_MCAST)) 3015 goto drop; 3016 if (isipv6) { 3017 struct ip6_hdr *ip6; 3018 3019 /* IPv6 anycast check is done at tcp6_input() */ 3020 ip6 = mtod(m, struct ip6_hdr *); 3021 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 3022 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) 3023 goto drop; 3024 } else { 3025 struct ip *ip; 3026 3027 ip = mtod(m, struct ip *); 3028 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || 3029 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 3030 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || 3031 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 3032 goto drop; 3033 } 3034 if (thflags & TH_ACK) { 3035 tcp_respond(NULL, 3036 mtod(m, void *), th, m, 0, th->th_ack, TH_RST); 3037 } else { 3038 seq = th->th_seq + (thflags & TH_SYN ? 1 : 0); 3039 tcp_respond(NULL, 3040 mtod(m, void *), th, m, seq, 0, TH_RST|TH_ACK); 3041 } 3042 INP_UNLOCK(tw->tw_inpcb); 3043 return (0); 3044 3045 drop: 3046 INP_UNLOCK(tw->tw_inpcb); 3047 m_freem(m); 3048 return (0); 3049 }
Cache object: 286152bd9de601da3ef0a16b80f42a10
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