tcp_timewait.c revision 32752
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 1.40 1997/12/19 03:36:14 julian Exp $ 35 */ 36 37#include "opt_compat.h" 38#include "opt_tcpdebug.h" 39 40#include <sys/param.h> 41#include <sys/systm.h> 42#include <sys/kernel.h> 43#include <sys/sysctl.h> 44#include <sys/malloc.h> 45#include <sys/mbuf.h> 46#include <sys/socket.h> 47#include <sys/socketvar.h> 48#include <sys/protosw.h> 49 50#include <net/route.h> 51#include <net/if.h> 52 53#define _IP_VHL 54#include <netinet/in.h> 55#include <netinet/in_systm.h> 56#include <netinet/ip.h> 57#include <netinet/in_pcb.h> 58#include <netinet/in_var.h> 59#include <netinet/ip_var.h> 60#include <netinet/tcp.h> 61#include <netinet/tcp_fsm.h> 62#include <netinet/tcp_seq.h> 63#include <netinet/tcp_timer.h> 64#include <netinet/tcp_var.h> 65#include <netinet/tcpip.h> 66#ifdef TCPDEBUG 67#include <netinet/tcp_debug.h> 68#endif 69 70int tcp_mssdflt = TCP_MSS; 71SYSCTL_INT(_net_inet_tcp, TCPCTL_MSSDFLT, mssdflt, 72 CTLFLAG_RW, &tcp_mssdflt , 0, ""); 73 74static int tcp_rttdflt = TCPTV_SRTTDFLT / PR_SLOWHZ; 75SYSCTL_INT(_net_inet_tcp, TCPCTL_RTTDFLT, rttdflt, 76 CTLFLAG_RW, &tcp_rttdflt , 0, ""); 77 78static int tcp_do_rfc1323 = 1; 79SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323, 80 CTLFLAG_RW, &tcp_do_rfc1323 , 0, ""); 81 82static int tcp_do_rfc1644 = 1; 83SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1644, rfc1644, 84 CTLFLAG_RW, &tcp_do_rfc1644 , 0, ""); 85 86static void tcp_cleartaocache __P((void)); 87static void tcp_notify __P((struct inpcb *, int)); 88 89/* 90 * Target size of TCP PCB hash table. Will be rounded down to a prime 91 * number. 92 */ 93#ifndef TCBHASHSIZE 94#define TCBHASHSIZE 128 95#endif 96 97/* 98 * Tcp initialization 99 */ 100void 101tcp_init() 102{ 103 104 tcp_iss = random(); /* wrong, but better than a constant */ 105 tcp_ccgen = 1; 106 tcp_cleartaocache(); 107 LIST_INIT(&tcb); 108 tcbinfo.listhead = &tcb; 109 tcbinfo.hashbase = hashinit(TCBHASHSIZE, M_PCB, &tcbinfo.hashmask); 110 if (max_protohdr < sizeof(struct tcpiphdr)) 111 max_protohdr = sizeof(struct tcpiphdr); 112 if (max_linkhdr + sizeof(struct tcpiphdr) > MHLEN) 113 panic("tcp_init"); 114} 115 116/* 117 * Create template to be used to send tcp packets on a connection. 118 * Call after host entry created, allocates an mbuf and fills 119 * in a skeletal tcp/ip header, minimizing the amount of work 120 * necessary when the connection is used. 121 */ 122struct tcpiphdr * 123tcp_template(tp) 124 struct tcpcb *tp; 125{ 126 register struct inpcb *inp = tp->t_inpcb; 127 register struct mbuf *m; 128 register struct tcpiphdr *n; 129 130 if ((n = tp->t_template) == 0) { 131 m = m_get(M_DONTWAIT, MT_HEADER); 132 if (m == NULL) 133 return (0); 134 m->m_len = sizeof (struct tcpiphdr); 135 n = mtod(m, struct tcpiphdr *); 136 } 137 n->ti_next = n->ti_prev = 0; 138 n->ti_x1 = 0; 139 n->ti_pr = IPPROTO_TCP; 140 n->ti_len = htons(sizeof (struct tcpiphdr) - sizeof (struct ip)); 141 n->ti_src = inp->inp_laddr; 142 n->ti_dst = inp->inp_faddr; 143 n->ti_sport = inp->inp_lport; 144 n->ti_dport = inp->inp_fport; 145 n->ti_seq = 0; 146 n->ti_ack = 0; 147 n->ti_x2 = 0; 148 n->ti_off = 5; 149 n->ti_flags = 0; 150 n->ti_win = 0; 151 n->ti_sum = 0; 152 n->ti_urp = 0; 153 return (n); 154} 155 156/* 157 * Send a single message to the TCP at address specified by 158 * the given TCP/IP header. If m == 0, then we make a copy 159 * of the tcpiphdr at ti and send directly to the addressed host. 160 * This is used to force keep alive messages out using the TCP 161 * template for a connection tp->t_template. If flags are given 162 * then we send a message back to the TCP which originated the 163 * segment ti, and discard the mbuf containing it and any other 164 * attached mbufs. 165 * 166 * In any case the ack and sequence number of the transmitted 167 * segment are as specified by the parameters. 168 * 169 * NOTE: If m != NULL, then ti must point to *inside* the mbuf. 170 */ 171void 172tcp_respond(tp, ti, m, ack, seq, flags) 173 struct tcpcb *tp; 174 register struct tcpiphdr *ti; 175 register struct mbuf *m; 176 tcp_seq ack, seq; 177 int flags; 178{ 179 register int tlen; 180 int win = 0; 181 struct route *ro = 0; 182 struct route sro; 183 184 if (tp) { 185 win = sbspace(&tp->t_inpcb->inp_socket->so_rcv); 186 ro = &tp->t_inpcb->inp_route; 187 } else { 188 ro = &sro; 189 bzero(ro, sizeof *ro); 190 } 191 if (m == 0) { 192 m = m_gethdr(M_DONTWAIT, MT_HEADER); 193 if (m == NULL) 194 return; 195#ifdef TCP_COMPAT_42 196 tlen = 1; 197#else 198 tlen = 0; 199#endif 200 m->m_data += max_linkhdr; 201 *mtod(m, struct tcpiphdr *) = *ti; 202 ti = mtod(m, struct tcpiphdr *); 203 flags = TH_ACK; 204 } else { 205 m_freem(m->m_next); 206 m->m_next = 0; 207 m->m_data = (caddr_t)ti; 208 m->m_len = sizeof (struct tcpiphdr); 209 tlen = 0; 210#define xchg(a,b,type) { type t; t=a; a=b; b=t; } 211 xchg(ti->ti_dst.s_addr, ti->ti_src.s_addr, u_long); 212 xchg(ti->ti_dport, ti->ti_sport, u_short); 213#undef xchg 214 } 215 ti->ti_len = htons((u_short)(sizeof (struct tcphdr) + tlen)); 216 tlen += sizeof (struct tcpiphdr); 217 m->m_len = tlen; 218 m->m_pkthdr.len = tlen; 219 m->m_pkthdr.rcvif = (struct ifnet *) 0; 220 ti->ti_next = ti->ti_prev = 0; 221 ti->ti_x1 = 0; 222 ti->ti_seq = htonl(seq); 223 ti->ti_ack = htonl(ack); 224 ti->ti_x2 = 0; 225 ti->ti_off = sizeof (struct tcphdr) >> 2; 226 ti->ti_flags = flags; 227 if (tp) 228 ti->ti_win = htons((u_short) (win >> tp->rcv_scale)); 229 else 230 ti->ti_win = htons((u_short)win); 231 ti->ti_urp = 0; 232 ti->ti_sum = 0; 233 ti->ti_sum = in_cksum(m, tlen); 234 ((struct ip *)ti)->ip_len = tlen; 235 ((struct ip *)ti)->ip_ttl = ip_defttl; 236#ifdef TCPDEBUG 237 if (tp == NULL || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 238 tcp_trace(TA_OUTPUT, 0, tp, ti, 0); 239#endif 240 (void) ip_output(m, NULL, ro, 0, NULL); 241 if (ro == &sro && ro->ro_rt) { 242 RTFREE(ro->ro_rt); 243 } 244} 245 246/* 247 * Create a new TCP control block, making an 248 * empty reassembly queue and hooking it to the argument 249 * protocol control block. 250 */ 251struct tcpcb * 252tcp_newtcpcb(inp) 253 struct inpcb *inp; 254{ 255 register struct tcpcb *tp; 256 257 tp = malloc(sizeof(*tp), M_PCB, M_NOWAIT); 258 if (tp == NULL) 259 return ((struct tcpcb *)0); 260 bzero((char *) tp, sizeof(struct tcpcb)); 261 tp->seg_next = tp->seg_prev = (struct tcpiphdr *)tp; 262 tp->t_maxseg = tp->t_maxopd = tcp_mssdflt; 263 264 if (tcp_do_rfc1323) 265 tp->t_flags = (TF_REQ_SCALE|TF_REQ_TSTMP); 266 if (tcp_do_rfc1644) 267 tp->t_flags |= TF_REQ_CC; 268 tp->t_inpcb = inp; 269 /* 270 * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no 271 * rtt estimate. Set rttvar so that srtt + 4 * rttvar gives 272 * reasonable initial retransmit time. 273 */ 274 tp->t_srtt = TCPTV_SRTTBASE; 275 tp->t_rttvar = ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4; 276 tp->t_rttmin = TCPTV_MIN; 277 tp->t_rxtcur = TCPTV_RTOBASE; 278 tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 279 tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT; 280 inp->inp_ip_ttl = ip_defttl; 281 inp->inp_ppcb = (caddr_t)tp; 282 return (tp); 283} 284 285/* 286 * Drop a TCP connection, reporting 287 * the specified error. If connection is synchronized, 288 * then send a RST to peer. 289 */ 290struct tcpcb * 291tcp_drop(tp, errno) 292 register struct tcpcb *tp; 293 int errno; 294{ 295 struct socket *so = tp->t_inpcb->inp_socket; 296 297 if (TCPS_HAVERCVDSYN(tp->t_state)) { 298 tp->t_state = TCPS_CLOSED; 299 (void) tcp_output(tp); 300 tcpstat.tcps_drops++; 301 } else 302 tcpstat.tcps_conndrops++; 303 if (errno == ETIMEDOUT && tp->t_softerror) 304 errno = tp->t_softerror; 305 so->so_error = errno; 306 return (tcp_close(tp)); 307} 308 309/* 310 * Close a TCP control block: 311 * discard all space held by the tcp 312 * discard internet protocol block 313 * wake up any sleepers 314 */ 315struct tcpcb * 316tcp_close(tp) 317 register struct tcpcb *tp; 318{ 319 register struct tcpiphdr *t; 320 struct inpcb *inp = tp->t_inpcb; 321 struct socket *so = inp->inp_socket; 322 register struct mbuf *m; 323 register struct rtentry *rt; 324 int dosavessthresh; 325 326 /* 327 * If we got enough samples through the srtt filter, 328 * save the rtt and rttvar in the routing entry. 329 * 'Enough' is arbitrarily defined as the 16 samples. 330 * 16 samples is enough for the srtt filter to converge 331 * to within 5% of the correct value; fewer samples and 332 * we could save a very bogus rtt. 333 * 334 * Don't update the default route's characteristics and don't 335 * update anything that the user "locked". 336 */ 337 if (tp->t_rttupdated >= 16 && 338 (rt = inp->inp_route.ro_rt) && 339 ((struct sockaddr_in *)rt_key(rt))->sin_addr.s_addr != INADDR_ANY) { 340 register u_long i = 0; 341 342 if ((rt->rt_rmx.rmx_locks & RTV_RTT) == 0) { 343 i = tp->t_srtt * 344 (RTM_RTTUNIT / (PR_SLOWHZ * TCP_RTT_SCALE)); 345 if (rt->rt_rmx.rmx_rtt && i) 346 /* 347 * filter this update to half the old & half 348 * the new values, converting scale. 349 * See route.h and tcp_var.h for a 350 * description of the scaling constants. 351 */ 352 rt->rt_rmx.rmx_rtt = 353 (rt->rt_rmx.rmx_rtt + i) / 2; 354 else 355 rt->rt_rmx.rmx_rtt = i; 356 tcpstat.tcps_cachedrtt++; 357 } 358 if ((rt->rt_rmx.rmx_locks & RTV_RTTVAR) == 0) { 359 i = tp->t_rttvar * 360 (RTM_RTTUNIT / (PR_SLOWHZ * TCP_RTTVAR_SCALE)); 361 if (rt->rt_rmx.rmx_rttvar && i) 362 rt->rt_rmx.rmx_rttvar = 363 (rt->rt_rmx.rmx_rttvar + i) / 2; 364 else 365 rt->rt_rmx.rmx_rttvar = i; 366 tcpstat.tcps_cachedrttvar++; 367 } 368 /* 369 * The old comment here said: 370 * update the pipelimit (ssthresh) if it has been updated 371 * already or if a pipesize was specified & the threshhold 372 * got below half the pipesize. I.e., wait for bad news 373 * before we start updating, then update on both good 374 * and bad news. 375 * 376 * But we want to save the ssthresh even if no pipesize is 377 * specified explicitly in the route, because such 378 * connections still have an implicit pipesize specified 379 * by the global tcp_sendspace. In the absence of a reliable 380 * way to calculate the pipesize, it will have to do. 381 */ 382 i = tp->snd_ssthresh; 383#if 1 384 if (rt->rt_rmx.rmx_sendpipe != 0) 385 dosavessthresh = (i < rt->rt_rmx.rmx_sendpipe / 2); 386 else 387 dosavessthresh = (i < so->so_snd.sb_hiwat / 2); 388#else 389 dosavessthresh = (i < rt->rt_rmx.rmx_sendpipe / 2); 390#endif 391 if (((rt->rt_rmx.rmx_locks & RTV_SSTHRESH) == 0 && 392 i != 0 && rt->rt_rmx.rmx_ssthresh != 0) 393 || dosavessthresh) { 394 /* 395 * convert the limit from user data bytes to 396 * packets then to packet data bytes. 397 */ 398 i = (i + tp->t_maxseg / 2) / tp->t_maxseg; 399 if (i < 2) 400 i = 2; 401 i *= (u_long)(tp->t_maxseg + sizeof (struct tcpiphdr)); 402 if (rt->rt_rmx.rmx_ssthresh) 403 rt->rt_rmx.rmx_ssthresh = 404 (rt->rt_rmx.rmx_ssthresh + i) / 2; 405 else 406 rt->rt_rmx.rmx_ssthresh = i; 407 tcpstat.tcps_cachedssthresh++; 408 } 409 } 410 /* free the reassembly queue, if any */ 411 t = tp->seg_next; 412 while (t != (struct tcpiphdr *)tp) { 413 t = (struct tcpiphdr *)t->ti_next; 414 m = REASS_MBUF((struct tcpiphdr *)t->ti_prev); 415 remque(t->ti_prev); 416 m_freem(m); 417 } 418 if (tp->t_template) 419 (void) m_free(dtom(tp->t_template)); 420 free(tp, M_PCB); 421 inp->inp_ppcb = 0; 422 soisdisconnected(so); 423 in_pcbdetach(inp); 424 tcpstat.tcps_closed++; 425 return ((struct tcpcb *)0); 426} 427 428void 429tcp_drain() 430{ 431 432} 433 434/* 435 * Notify a tcp user of an asynchronous error; 436 * store error as soft error, but wake up user 437 * (for now, won't do anything until can select for soft error). 438 */ 439static void 440tcp_notify(inp, error) 441 struct inpcb *inp; 442 int error; 443{ 444 register struct tcpcb *tp = (struct tcpcb *)inp->inp_ppcb; 445 register struct socket *so = inp->inp_socket; 446 447 /* 448 * Ignore some errors if we are hooked up. 449 * If connection hasn't completed, has retransmitted several times, 450 * and receives a second error, give up now. This is better 451 * than waiting a long time to establish a connection that 452 * can never complete. 453 */ 454 if (tp->t_state == TCPS_ESTABLISHED && 455 (error == EHOSTUNREACH || error == ENETUNREACH || 456 error == EHOSTDOWN)) { 457 return; 458 } else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 && 459 tp->t_softerror) 460 so->so_error = error; 461 else 462 tp->t_softerror = error; 463 wakeup((caddr_t) &so->so_timeo); 464 sorwakeup(so); 465 sowwakeup(so); 466} 467 468void 469tcp_ctlinput(cmd, sa, vip) 470 int cmd; 471 struct sockaddr *sa; 472 void *vip; 473{ 474 register struct ip *ip = vip; 475 register struct tcphdr *th; 476 void (*notify) __P((struct inpcb *, int)) = tcp_notify; 477 478 if (cmd == PRC_QUENCH) 479 notify = tcp_quench; 480#if 1 481 else if (cmd == PRC_MSGSIZE) 482 notify = tcp_mtudisc; 483#endif 484 else if (!PRC_IS_REDIRECT(cmd) && 485 ((unsigned)cmd > PRC_NCMDS || inetctlerrmap[cmd] == 0)) 486 return; 487 if (ip) { 488 th = (struct tcphdr *)((caddr_t)ip 489 + (IP_VHL_HL(ip->ip_vhl) << 2)); 490 in_pcbnotify(&tcb, sa, th->th_dport, ip->ip_src, th->th_sport, 491 cmd, notify); 492 } else 493 in_pcbnotify(&tcb, sa, 0, zeroin_addr, 0, cmd, notify); 494} 495 496/* 497 * When a source quench is received, close congestion window 498 * to one segment. We will gradually open it again as we proceed. 499 */ 500void 501tcp_quench(inp, errno) 502 struct inpcb *inp; 503 int errno; 504{ 505 struct tcpcb *tp = intotcpcb(inp); 506 507 if (tp) 508 tp->snd_cwnd = tp->t_maxseg; 509} 510 511#if 1 512/* 513 * When `need fragmentation' ICMP is received, update our idea of the MSS 514 * based on the new value in the route. Also nudge TCP to send something, 515 * since we know the packet we just sent was dropped. 516 * This duplicates some code in the tcp_mss() function in tcp_input.c. 517 */ 518void 519tcp_mtudisc(inp, errno) 520 struct inpcb *inp; 521 int errno; 522{ 523 struct tcpcb *tp = intotcpcb(inp); 524 struct rtentry *rt; 525 struct rmxp_tao *taop; 526 struct socket *so = inp->inp_socket; 527 int offered; 528 int mss; 529 530 if (tp) { 531 rt = tcp_rtlookup(inp); 532 if (!rt || !rt->rt_rmx.rmx_mtu) { 533 tp->t_maxopd = tp->t_maxseg = tcp_mssdflt; 534 return; 535 } 536 taop = rmx_taop(rt->rt_rmx); 537 offered = taop->tao_mssopt; 538 mss = rt->rt_rmx.rmx_mtu - sizeof(struct tcpiphdr); 539 if (offered) 540 mss = min(mss, offered); 541 /* 542 * XXX - The above conditional probably violates the TCP 543 * spec. The problem is that, since we don't know the 544 * other end's MSS, we are supposed to use a conservative 545 * default. But, if we do that, then MTU discovery will 546 * never actually take place, because the conservative 547 * default is much less than the MTUs typically seen 548 * on the Internet today. For the moment, we'll sweep 549 * this under the carpet. 550 * 551 * The conservative default might not actually be a problem 552 * if the only case this occurs is when sending an initial 553 * SYN with options and data to a host we've never talked 554 * to before. Then, they will reply with an MSS value which 555 * will get recorded and the new parameters should get 556 * recomputed. For Further Study. 557 */ 558 if (tp->t_maxopd <= mss) 559 return; 560 tp->t_maxopd = mss; 561 562 if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP && 563 (tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP) 564 mss -= TCPOLEN_TSTAMP_APPA; 565 if ((tp->t_flags & (TF_REQ_CC|TF_NOOPT)) == TF_REQ_CC && 566 (tp->t_flags & TF_RCVD_CC) == TF_RCVD_CC) 567 mss -= TCPOLEN_CC_APPA; 568#if (MCLBYTES & (MCLBYTES - 1)) == 0 569 if (mss > MCLBYTES) 570 mss &= ~(MCLBYTES-1); 571#else 572 if (mss > MCLBYTES) 573 mss = mss / MCLBYTES * MCLBYTES; 574#endif 575 if (so->so_snd.sb_hiwat < mss) 576 mss = so->so_snd.sb_hiwat; 577 578 tp->t_maxseg = mss; 579 580 tcpstat.tcps_mturesent++; 581 tp->t_rtt = 0; 582 tp->snd_nxt = tp->snd_una; 583 tcp_output(tp); 584 } 585} 586#endif 587 588/* 589 * Look-up the routing entry to the peer of this inpcb. If no route 590 * is found and it cannot be allocated the return NULL. This routine 591 * is called by TCP routines that access the rmx structure and by tcp_mss 592 * to get the interface MTU. 593 */ 594struct rtentry * 595tcp_rtlookup(inp) 596 struct inpcb *inp; 597{ 598 struct route *ro; 599 struct rtentry *rt; 600 601 ro = &inp->inp_route; 602 rt = ro->ro_rt; 603 if (rt == NULL || !(rt->rt_flags & RTF_UP)) { 604 /* No route yet, so try to acquire one */ 605 if (inp->inp_faddr.s_addr != INADDR_ANY) { 606 ro->ro_dst.sa_family = AF_INET; 607 ro->ro_dst.sa_len = sizeof(ro->ro_dst); 608 ((struct sockaddr_in *) &ro->ro_dst)->sin_addr = 609 inp->inp_faddr; 610 rtalloc(ro); 611 rt = ro->ro_rt; 612 } 613 } 614 return rt; 615} 616 617/* 618 * Return a pointer to the cached information about the remote host. 619 * The cached information is stored in the protocol specific part of 620 * the route metrics. 621 */ 622struct rmxp_tao * 623tcp_gettaocache(inp) 624 struct inpcb *inp; 625{ 626 struct rtentry *rt = tcp_rtlookup(inp); 627 628 /* Make sure this is a host route and is up. */ 629 if (rt == NULL || 630 (rt->rt_flags & (RTF_UP|RTF_HOST)) != (RTF_UP|RTF_HOST)) 631 return NULL; 632 633 return rmx_taop(rt->rt_rmx); 634} 635 636/* 637 * Clear all the TAO cache entries, called from tcp_init. 638 * 639 * XXX 640 * This routine is just an empty one, because we assume that the routing 641 * routing tables are initialized at the same time when TCP, so there is 642 * nothing in the cache left over. 643 */ 644static void 645tcp_cleartaocache() 646{ 647} 648