tcp_timewait.c revision 30813
1/* 2 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 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_subr.c 8.2 (Berkeley) 5/24/95 34 * $Id: tcp_subr.c,v 1.38 1997/09/16 18:36:06 joerg Exp $ 35 */ 36 37#include "opt_tcpdebug.h" 38 39#include <sys/param.h> 40#include <sys/systm.h> 41#include <sys/kernel.h> 42#include <sys/sysctl.h> 43#include <sys/malloc.h> 44#include <sys/mbuf.h> 45#include <sys/socket.h> 46#include <sys/socketvar.h> 47#include <sys/protosw.h> 48 49#include <net/route.h> 50#include <net/if.h> 51 52#define _IP_VHL 53#include <netinet/in.h> 54#include <netinet/in_systm.h> 55#include <netinet/ip.h> 56#include <netinet/in_pcb.h> 57#include <netinet/in_var.h> 58#include <netinet/ip_var.h> 59#include <netinet/tcp.h> 60#include <netinet/tcp_fsm.h> 61#include <netinet/tcp_seq.h> 62#include <netinet/tcp_timer.h> 63#include <netinet/tcp_var.h> 64#include <netinet/tcpip.h> 65#ifdef TCPDEBUG 66#include <netinet/tcp_debug.h> 67#endif 68 69int tcp_mssdflt = TCP_MSS; 70SYSCTL_INT(_net_inet_tcp, TCPCTL_MSSDFLT, mssdflt, 71 CTLFLAG_RW, &tcp_mssdflt , 0, ""); 72 73static int tcp_rttdflt = TCPTV_SRTTDFLT / PR_SLOWHZ; 74SYSCTL_INT(_net_inet_tcp, TCPCTL_RTTDFLT, rttdflt, 75 CTLFLAG_RW, &tcp_rttdflt , 0, ""); 76 77static int tcp_do_rfc1323 = 1; 78SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323, 79 CTLFLAG_RW, &tcp_do_rfc1323 , 0, ""); 80 81static int tcp_do_rfc1644 = 1; 82SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1644, rfc1644, 83 CTLFLAG_RW, &tcp_do_rfc1644 , 0, ""); 84 85static void tcp_cleartaocache __P((void)); 86static void tcp_notify __P((struct inpcb *, int)); 87 88/* 89 * Target size of TCP PCB hash table. Will be rounded down to a prime 90 * number. 91 */ 92#ifndef TCBHASHSIZE 93#define TCBHASHSIZE 128 94#endif 95 96/* 97 * Tcp initialization 98 */ 99void 100tcp_init() 101{ 102 103 tcp_iss = random(); /* wrong, but better than a constant */ 104 tcp_ccgen = 1; 105 tcp_cleartaocache(); 106 LIST_INIT(&tcb); 107 tcbinfo.listhead = &tcb; 108 tcbinfo.hashbase = hashinit(TCBHASHSIZE, M_PCB, &tcbinfo.hashmask); 109 if (max_protohdr < sizeof(struct tcpiphdr)) 110 max_protohdr = sizeof(struct tcpiphdr); 111 if (max_linkhdr + sizeof(struct tcpiphdr) > MHLEN) 112 panic("tcp_init"); 113} 114 115/* 116 * Create template to be used to send tcp packets on a connection. 117 * Call after host entry created, allocates an mbuf and fills 118 * in a skeletal tcp/ip header, minimizing the amount of work 119 * necessary when the connection is used. 120 */ 121struct tcpiphdr * 122tcp_template(tp) 123 struct tcpcb *tp; 124{ 125 register struct inpcb *inp = tp->t_inpcb; 126 register struct mbuf *m; 127 register struct tcpiphdr *n; 128 129 if ((n = tp->t_template) == 0) { 130 m = m_get(M_DONTWAIT, MT_HEADER); 131 if (m == NULL) 132 return (0); 133 m->m_len = sizeof (struct tcpiphdr); 134 n = mtod(m, struct tcpiphdr *); 135 } 136 n->ti_next = n->ti_prev = 0; 137 n->ti_x1 = 0; 138 n->ti_pr = IPPROTO_TCP; 139 n->ti_len = htons(sizeof (struct tcpiphdr) - sizeof (struct ip)); 140 n->ti_src = inp->inp_laddr; 141 n->ti_dst = inp->inp_faddr; 142 n->ti_sport = inp->inp_lport; 143 n->ti_dport = inp->inp_fport; 144 n->ti_seq = 0; 145 n->ti_ack = 0; 146 n->ti_x2 = 0; 147 n->ti_off = 5; 148 n->ti_flags = 0; 149 n->ti_win = 0; 150 n->ti_sum = 0; 151 n->ti_urp = 0; 152 return (n); 153} 154 155/* 156 * Send a single message to the TCP at address specified by 157 * the given TCP/IP header. If m == 0, then we make a copy 158 * of the tcpiphdr at ti and send directly to the addressed host. 159 * This is used to force keep alive messages out using the TCP 160 * template for a connection tp->t_template. If flags are given 161 * then we send a message back to the TCP which originated the 162 * segment ti, and discard the mbuf containing it and any other 163 * attached mbufs. 164 * 165 * In any case the ack and sequence number of the transmitted 166 * segment are as specified by the parameters. 167 */ 168void 169tcp_respond(tp, ti, m, ack, seq, flags) 170 struct tcpcb *tp; 171 register struct tcpiphdr *ti; 172 register struct mbuf *m; 173 tcp_seq ack, seq; 174 int flags; 175{ 176 register int tlen; 177 int win = 0; 178 struct route *ro = 0; 179 struct route sro; 180 181 if (tp) { 182 win = sbspace(&tp->t_inpcb->inp_socket->so_rcv); 183 ro = &tp->t_inpcb->inp_route; 184 } else { 185 ro = &sro; 186 bzero(ro, sizeof *ro); 187 } 188 if (m == 0) { 189 m = m_gethdr(M_DONTWAIT, MT_HEADER); 190 if (m == NULL) 191 return; 192#ifdef TCP_COMPAT_42 193 tlen = 1; 194#else 195 tlen = 0; 196#endif 197 m->m_data += max_linkhdr; 198 *mtod(m, struct tcpiphdr *) = *ti; 199 ti = mtod(m, struct tcpiphdr *); 200 flags = TH_ACK; 201 } else { 202 m_freem(m->m_next); 203 m->m_next = 0; 204 m->m_data = (caddr_t)ti; 205 m->m_len = sizeof (struct tcpiphdr); 206 tlen = 0; 207#define xchg(a,b,type) { type t; t=a; a=b; b=t; } 208 xchg(ti->ti_dst.s_addr, ti->ti_src.s_addr, u_long); 209 xchg(ti->ti_dport, ti->ti_sport, u_short); 210#undef xchg 211 } 212 ti->ti_len = htons((u_short)(sizeof (struct tcphdr) + tlen)); 213 tlen += sizeof (struct tcpiphdr); 214 m->m_len = tlen; 215 m->m_pkthdr.len = tlen; 216 m->m_pkthdr.rcvif = (struct ifnet *) 0; 217 ti->ti_next = ti->ti_prev = 0; 218 ti->ti_x1 = 0; 219 ti->ti_seq = htonl(seq); 220 ti->ti_ack = htonl(ack); 221 ti->ti_x2 = 0; 222 ti->ti_off = sizeof (struct tcphdr) >> 2; 223 ti->ti_flags = flags; 224 if (tp) 225 ti->ti_win = htons((u_short) (win >> tp->rcv_scale)); 226 else 227 ti->ti_win = htons((u_short)win); 228 ti->ti_urp = 0; 229 ti->ti_sum = 0; 230 ti->ti_sum = in_cksum(m, tlen); 231 ((struct ip *)ti)->ip_len = tlen; 232 ((struct ip *)ti)->ip_ttl = ip_defttl; 233#ifdef TCPDEBUG 234 if (tp == NULL || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 235 tcp_trace(TA_OUTPUT, 0, tp, ti, 0); 236#endif 237 (void) ip_output(m, NULL, ro, 0, NULL); 238 if (ro == &sro && ro->ro_rt) { 239 RTFREE(ro->ro_rt); 240 } 241} 242 243/* 244 * Create a new TCP control block, making an 245 * empty reassembly queue and hooking it to the argument 246 * protocol control block. 247 */ 248struct tcpcb * 249tcp_newtcpcb(inp) 250 struct inpcb *inp; 251{ 252 register struct tcpcb *tp; 253 254 tp = malloc(sizeof(*tp), M_PCB, M_NOWAIT); 255 if (tp == NULL) 256 return ((struct tcpcb *)0); 257 bzero((char *) tp, sizeof(struct tcpcb)); 258 tp->seg_next = tp->seg_prev = (struct tcpiphdr *)tp; 259 tp->t_maxseg = tp->t_maxopd = tcp_mssdflt; 260 261 if (tcp_do_rfc1323) 262 tp->t_flags = (TF_REQ_SCALE|TF_REQ_TSTMP); 263 if (tcp_do_rfc1644) 264 tp->t_flags |= TF_REQ_CC; 265 tp->t_inpcb = inp; 266 /* 267 * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no 268 * rtt estimate. Set rttvar so that srtt + 4 * rttvar gives 269 * reasonable initial retransmit time. 270 */ 271 tp->t_srtt = TCPTV_SRTTBASE; 272 tp->t_rttvar = ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4; 273 tp->t_rttmin = TCPTV_MIN; 274 tp->t_rxtcur = TCPTV_RTOBASE; 275 tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 276 tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT; 277 inp->inp_ip_ttl = ip_defttl; 278 inp->inp_ppcb = (caddr_t)tp; 279 return (tp); 280} 281 282/* 283 * Drop a TCP connection, reporting 284 * the specified error. If connection is synchronized, 285 * then send a RST to peer. 286 */ 287struct tcpcb * 288tcp_drop(tp, errno) 289 register struct tcpcb *tp; 290 int errno; 291{ 292 struct socket *so = tp->t_inpcb->inp_socket; 293 294 if (TCPS_HAVERCVDSYN(tp->t_state)) { 295 tp->t_state = TCPS_CLOSED; 296 (void) tcp_output(tp); 297 tcpstat.tcps_drops++; 298 } else 299 tcpstat.tcps_conndrops++; 300 if (errno == ETIMEDOUT && tp->t_softerror) 301 errno = tp->t_softerror; 302 so->so_error = errno; 303 return (tcp_close(tp)); 304} 305 306/* 307 * Close a TCP control block: 308 * discard all space held by the tcp 309 * discard internet protocol block 310 * wake up any sleepers 311 */ 312struct tcpcb * 313tcp_close(tp) 314 register struct tcpcb *tp; 315{ 316 register struct tcpiphdr *t; 317 struct inpcb *inp = tp->t_inpcb; 318 struct socket *so = inp->inp_socket; 319 register struct mbuf *m; 320 register struct rtentry *rt; 321 int dosavessthresh; 322 323 /* 324 * If we got enough samples through the srtt filter, 325 * save the rtt and rttvar in the routing entry. 326 * 'Enough' is arbitrarily defined as the 16 samples. 327 * 16 samples is enough for the srtt filter to converge 328 * to within 5% of the correct value; fewer samples and 329 * we could save a very bogus rtt. 330 * 331 * Don't update the default route's characteristics and don't 332 * update anything that the user "locked". 333 */ 334 if (tp->t_rttupdated >= 16 && 335 (rt = inp->inp_route.ro_rt) && 336 ((struct sockaddr_in *)rt_key(rt))->sin_addr.s_addr != INADDR_ANY) { 337 register u_long i = 0; 338 339 if ((rt->rt_rmx.rmx_locks & RTV_RTT) == 0) { 340 i = tp->t_srtt * 341 (RTM_RTTUNIT / (PR_SLOWHZ * TCP_RTT_SCALE)); 342 if (rt->rt_rmx.rmx_rtt && i) 343 /* 344 * filter this update to half the old & half 345 * the new values, converting scale. 346 * See route.h and tcp_var.h for a 347 * description of the scaling constants. 348 */ 349 rt->rt_rmx.rmx_rtt = 350 (rt->rt_rmx.rmx_rtt + i) / 2; 351 else 352 rt->rt_rmx.rmx_rtt = i; 353 tcpstat.tcps_cachedrtt++; 354 } 355 if ((rt->rt_rmx.rmx_locks & RTV_RTTVAR) == 0) { 356 i = tp->t_rttvar * 357 (RTM_RTTUNIT / (PR_SLOWHZ * TCP_RTTVAR_SCALE)); 358 if (rt->rt_rmx.rmx_rttvar && i) 359 rt->rt_rmx.rmx_rttvar = 360 (rt->rt_rmx.rmx_rttvar + i) / 2; 361 else 362 rt->rt_rmx.rmx_rttvar = i; 363 tcpstat.tcps_cachedrttvar++; 364 } 365 /* 366 * The old comment here said: 367 * update the pipelimit (ssthresh) if it has been updated 368 * already or if a pipesize was specified & the threshhold 369 * got below half the pipesize. I.e., wait for bad news 370 * before we start updating, then update on both good 371 * and bad news. 372 * 373 * But we want to save the ssthresh even if no pipesize is 374 * specified explicitly in the route, because such 375 * connections still have an implicit pipesize specified 376 * by the global tcp_sendspace. In the absence of a reliable 377 * way to calculate the pipesize, it will have to do. 378 */ 379 i = tp->snd_ssthresh; 380#if 1 381 if (rt->rt_rmx.rmx_sendpipe != 0) 382 dosavessthresh = (i < rt->rt_rmx.rmx_sendpipe / 2); 383 else 384 dosavessthresh = (i < so->so_snd.sb_hiwat / 2); 385#else 386 dosavessthresh = (i < rt->rt_rmx.rmx_sendpipe / 2); 387#endif 388 if (((rt->rt_rmx.rmx_locks & RTV_SSTHRESH) == 0 && 389 i != 0 && rt->rt_rmx.rmx_ssthresh != 0) 390 || dosavessthresh) { 391 /* 392 * convert the limit from user data bytes to 393 * packets then to packet data bytes. 394 */ 395 i = (i + tp->t_maxseg / 2) / tp->t_maxseg; 396 if (i < 2) 397 i = 2; 398 i *= (u_long)(tp->t_maxseg + sizeof (struct tcpiphdr)); 399 if (rt->rt_rmx.rmx_ssthresh) 400 rt->rt_rmx.rmx_ssthresh = 401 (rt->rt_rmx.rmx_ssthresh + i) / 2; 402 else 403 rt->rt_rmx.rmx_ssthresh = i; 404 tcpstat.tcps_cachedssthresh++; 405 } 406 } 407 /* free the reassembly queue, if any */ 408 t = tp->seg_next; 409 while (t != (struct tcpiphdr *)tp) { 410 t = (struct tcpiphdr *)t->ti_next; 411 m = REASS_MBUF((struct tcpiphdr *)t->ti_prev); 412 remque(t->ti_prev); 413 m_freem(m); 414 } 415 if (tp->t_template) 416 (void) m_free(dtom(tp->t_template)); 417 free(tp, M_PCB); 418 inp->inp_ppcb = 0; 419 soisdisconnected(so); 420 in_pcbdetach(inp); 421 tcpstat.tcps_closed++; 422 return ((struct tcpcb *)0); 423} 424 425void 426tcp_drain() 427{ 428 429} 430 431/* 432 * Notify a tcp user of an asynchronous error; 433 * store error as soft error, but wake up user 434 * (for now, won't do anything until can select for soft error). 435 */ 436static void 437tcp_notify(inp, error) 438 struct inpcb *inp; 439 int error; 440{ 441 register struct tcpcb *tp = (struct tcpcb *)inp->inp_ppcb; 442 register struct socket *so = inp->inp_socket; 443 444 /* 445 * Ignore some errors if we are hooked up. 446 * If connection hasn't completed, has retransmitted several times, 447 * and receives a second error, give up now. This is better 448 * than waiting a long time to establish a connection that 449 * can never complete. 450 */ 451 if (tp->t_state == TCPS_ESTABLISHED && 452 (error == EHOSTUNREACH || error == ENETUNREACH || 453 error == EHOSTDOWN)) { 454 return; 455 } else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 && 456 tp->t_softerror) 457 so->so_error = error; 458 else 459 tp->t_softerror = error; 460 wakeup((caddr_t) &so->so_timeo); 461 sorwakeup(so); 462 sowwakeup(so); 463} 464 465void 466tcp_ctlinput(cmd, sa, vip) 467 int cmd; 468 struct sockaddr *sa; 469 void *vip; 470{ 471 register struct ip *ip = vip; 472 register struct tcphdr *th; 473 void (*notify) __P((struct inpcb *, int)) = tcp_notify; 474 475 if (cmd == PRC_QUENCH) 476 notify = tcp_quench; 477#if 1 478 else if (cmd == PRC_MSGSIZE) 479 notify = tcp_mtudisc; 480#endif 481 else if (!PRC_IS_REDIRECT(cmd) && 482 ((unsigned)cmd > PRC_NCMDS || inetctlerrmap[cmd] == 0)) 483 return; 484 if (ip) { 485 th = (struct tcphdr *)((caddr_t)ip 486 + (IP_VHL_HL(ip->ip_vhl) << 2)); 487 in_pcbnotify(&tcb, sa, th->th_dport, ip->ip_src, th->th_sport, 488 cmd, notify); 489 } else 490 in_pcbnotify(&tcb, sa, 0, zeroin_addr, 0, cmd, notify); 491} 492 493/* 494 * When a source quench is received, close congestion window 495 * to one segment. We will gradually open it again as we proceed. 496 */ 497void 498tcp_quench(inp, errno) 499 struct inpcb *inp; 500 int errno; 501{ 502 struct tcpcb *tp = intotcpcb(inp); 503 504 if (tp) 505 tp->snd_cwnd = tp->t_maxseg; 506} 507 508#if 1 509/* 510 * When `need fragmentation' ICMP is received, update our idea of the MSS 511 * based on the new value in the route. Also nudge TCP to send something, 512 * since we know the packet we just sent was dropped. 513 * This duplicates some code in the tcp_mss() function in tcp_input.c. 514 */ 515void 516tcp_mtudisc(inp, errno) 517 struct inpcb *inp; 518 int errno; 519{ 520 struct tcpcb *tp = intotcpcb(inp); 521 struct rtentry *rt; 522 struct rmxp_tao *taop; 523 struct socket *so = inp->inp_socket; 524 int offered; 525 int mss; 526 527 if (tp) { 528 rt = tcp_rtlookup(inp); 529 if (!rt || !rt->rt_rmx.rmx_mtu) { 530 tp->t_maxopd = tp->t_maxseg = tcp_mssdflt; 531 return; 532 } 533 taop = rmx_taop(rt->rt_rmx); 534 offered = taop->tao_mssopt; 535 mss = rt->rt_rmx.rmx_mtu - sizeof(struct tcpiphdr); 536 if (offered) 537 mss = min(mss, offered); 538 /* 539 * XXX - The above conditional probably violates the TCP 540 * spec. The problem is that, since we don't know the 541 * other end's MSS, we are supposed to use a conservative 542 * default. But, if we do that, then MTU discovery will 543 * never actually take place, because the conservative 544 * default is much less than the MTUs typically seen 545 * on the Internet today. For the moment, we'll sweep 546 * this under the carpet. 547 * 548 * The conservative default might not actually be a problem 549 * if the only case this occurs is when sending an initial 550 * SYN with options and data to a host we've never talked 551 * to before. Then, they will reply with an MSS value which 552 * will get recorded and the new parameters should get 553 * recomputed. For Further Study. 554 */ 555 if (tp->t_maxopd <= mss) 556 return; 557 tp->t_maxopd = mss; 558 559 if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP && 560 (tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP) 561 mss -= TCPOLEN_TSTAMP_APPA; 562 if ((tp->t_flags & (TF_REQ_CC|TF_NOOPT)) == TF_REQ_CC && 563 (tp->t_flags & TF_RCVD_CC) == TF_RCVD_CC) 564 mss -= TCPOLEN_CC_APPA; 565#if (MCLBYTES & (MCLBYTES - 1)) == 0 566 if (mss > MCLBYTES) 567 mss &= ~(MCLBYTES-1); 568#else 569 if (mss > MCLBYTES) 570 mss = mss / MCLBYTES * MCLBYTES; 571#endif 572 if (so->so_snd.sb_hiwat < mss) 573 mss = so->so_snd.sb_hiwat; 574 575 tp->t_maxseg = mss; 576 577 tcpstat.tcps_mturesent++; 578 tp->t_rtt = 0; 579 tp->snd_nxt = tp->snd_una; 580 tcp_output(tp); 581 } 582} 583#endif 584 585/* 586 * Look-up the routing entry to the peer of this inpcb. If no route 587 * is found and it cannot be allocated the return NULL. This routine 588 * is called by TCP routines that access the rmx structure and by tcp_mss 589 * to get the interface MTU. 590 */ 591struct rtentry * 592tcp_rtlookup(inp) 593 struct inpcb *inp; 594{ 595 struct route *ro; 596 struct rtentry *rt; 597 598 ro = &inp->inp_route; 599 rt = ro->ro_rt; 600 if (rt == NULL || !(rt->rt_flags & RTF_UP)) { 601 /* No route yet, so try to acquire one */ 602 if (inp->inp_faddr.s_addr != INADDR_ANY) { 603 ro->ro_dst.sa_family = AF_INET; 604 ro->ro_dst.sa_len = sizeof(ro->ro_dst); 605 ((struct sockaddr_in *) &ro->ro_dst)->sin_addr = 606 inp->inp_faddr; 607 rtalloc(ro); 608 rt = ro->ro_rt; 609 } 610 } 611 return rt; 612} 613 614/* 615 * Return a pointer to the cached information about the remote host. 616 * The cached information is stored in the protocol specific part of 617 * the route metrics. 618 */ 619struct rmxp_tao * 620tcp_gettaocache(inp) 621 struct inpcb *inp; 622{ 623 struct rtentry *rt = tcp_rtlookup(inp); 624 625 /* Make sure this is a host route and is up. */ 626 if (rt == NULL || 627 (rt->rt_flags & (RTF_UP|RTF_HOST)) != (RTF_UP|RTF_HOST)) 628 return NULL; 629 630 return rmx_taop(rt->rt_rmx); 631} 632 633/* 634 * Clear all the TAO cache entries, called from tcp_init. 635 * 636 * XXX 637 * This routine is just an empty one, because we assume that the routing 638 * routing tables are initialized at the same time when TCP, so there is 639 * nothing in the cache left over. 640 */ 641static void 642tcp_cleartaocache() 643{ 644} 645