tcp_timewait.c revision 46381
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 1.53 1999/04/28 11:37:49 phk 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 <vm/vm_zone.h> 51 52#include <net/route.h> 53#include <net/if.h> 54 55#define _IP_VHL 56#include <netinet/in.h> 57#include <netinet/in_systm.h> 58#include <netinet/ip.h> 59#include <netinet/in_pcb.h> 60#include <netinet/in_var.h> 61#include <netinet/ip_var.h> 62#include <netinet/tcp.h> 63#include <netinet/tcp_fsm.h> 64#include <netinet/tcp_seq.h> 65#include <netinet/tcp_timer.h> 66#include <netinet/tcp_var.h> 67#include <netinet/tcpip.h> 68#ifdef TCPDEBUG 69#include <netinet/tcp_debug.h> 70#endif 71 72int tcp_mssdflt = TCP_MSS; 73SYSCTL_INT(_net_inet_tcp, TCPCTL_MSSDFLT, mssdflt, CTLFLAG_RW, 74 &tcp_mssdflt , 0, "Default TCP Maximum Segment Size"); 75 76static int tcp_rttdflt = TCPTV_SRTTDFLT / PR_SLOWHZ; 77SYSCTL_INT(_net_inet_tcp, TCPCTL_RTTDFLT, rttdflt, CTLFLAG_RW, 78 &tcp_rttdflt , 0, "Default maximum TCP Round Trip Time"); 79 80static int tcp_do_rfc1323 = 1; 81SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1323, rfc1323, CTLFLAG_RW, 82 &tcp_do_rfc1323 , 0, "Enable rfc1323 (high performance TCP) extensions"); 83 84static int tcp_do_rfc1644 = 0; 85SYSCTL_INT(_net_inet_tcp, TCPCTL_DO_RFC1644, rfc1644, CTLFLAG_RW, 86 &tcp_do_rfc1644 , 0, "Enable rfc1644 (TTCP) extensions"); 87 88SYSCTL_INT(_net_inet_tcp, OID_AUTO, pcbcount, CTLFLAG_RD, 89 &tcbinfo.ipi_count, 0, "Number of active PCBs"); 90 91static void tcp_cleartaocache __P((void)); 92static void tcp_notify __P((struct inpcb *, int)); 93 94/* 95 * Target size of TCP PCB hash tables. Must be a power of two. 96 * 97 * Note that this can be overridden by the kernel environment 98 * variable net.inet.tcp.tcbhashsize 99 */ 100#ifndef TCBHASHSIZE 101#define TCBHASHSIZE 512 102#endif 103 104/* 105 * This is the actual shape of what we allocate using the zone 106 * allocator. Doing it this way allows us to protect both structures 107 * using the same generation count, and also eliminates the overhead 108 * of allocating tcpcbs separately. By hiding the structure here, 109 * we avoid changing most of the rest of the code (although it needs 110 * to be changed, eventually, for greater efficiency). 111 */ 112#define ALIGNMENT 32 113#define ALIGNM1 (ALIGNMENT - 1) 114struct inp_tp { 115 union { 116 struct inpcb inp; 117 char align[(sizeof(struct inpcb) + ALIGNM1) & ~ALIGNM1]; 118 } inp_tp_u; 119 struct tcpcb tcb; 120}; 121#undef ALIGNMENT 122#undef ALIGNM1 123 124/* 125 * Tcp initialization 126 */ 127void 128tcp_init() 129{ 130 int hashsize; 131 132 tcp_iss = random(); /* wrong, but better than a constant */ 133 tcp_ccgen = 1; 134 tcp_cleartaocache(); 135 LIST_INIT(&tcb); 136 tcbinfo.listhead = &tcb; 137 if (!(getenv_int("net.inet.tcp.tcbhashsize", &hashsize))) 138 hashsize = TCBHASHSIZE; 139 if (!powerof2(hashsize)) { 140 printf("WARNING: TCB hash size not a power of 2\n"); 141 hashsize = 512; /* safe default */ 142 } 143 tcbinfo.hashbase = hashinit(hashsize, M_PCB, &tcbinfo.hashmask); 144 tcbinfo.porthashbase = hashinit(hashsize, M_PCB, 145 &tcbinfo.porthashmask); 146 tcbinfo.ipi_zone = zinit("tcpcb", sizeof(struct inp_tp), maxsockets, 147 ZONE_INTERRUPT, 0); 148 if (max_protohdr < sizeof(struct tcpiphdr)) 149 max_protohdr = sizeof(struct tcpiphdr); 150 if (max_linkhdr + sizeof(struct tcpiphdr) > MHLEN) 151 panic("tcp_init"); 152} 153 154/* 155 * Create template to be used to send tcp packets on a connection. 156 * Call after host entry created, allocates an mbuf and fills 157 * in a skeletal tcp/ip header, minimizing the amount of work 158 * necessary when the connection is used. 159 */ 160struct tcpiphdr * 161tcp_template(tp) 162 struct tcpcb *tp; 163{ 164 register struct inpcb *inp = tp->t_inpcb; 165 register struct mbuf *m; 166 register struct tcpiphdr *n; 167 168 if ((n = tp->t_template) == 0) { 169 m = m_get(M_DONTWAIT, MT_HEADER); 170 if (m == NULL) 171 return (0); 172 m->m_len = sizeof (struct tcpiphdr); 173 n = mtod(m, struct tcpiphdr *); 174 } 175 bzero(n->ti_x1, sizeof(n->ti_x1)); 176 n->ti_pr = IPPROTO_TCP; 177 n->ti_len = htons(sizeof (struct tcpiphdr) - sizeof (struct ip)); 178 n->ti_src = inp->inp_laddr; 179 n->ti_dst = inp->inp_faddr; 180 n->ti_sport = inp->inp_lport; 181 n->ti_dport = inp->inp_fport; 182 n->ti_seq = 0; 183 n->ti_ack = 0; 184 n->ti_x2 = 0; 185 n->ti_off = 5; 186 n->ti_flags = 0; 187 n->ti_win = 0; 188 n->ti_sum = 0; 189 n->ti_urp = 0; 190 return (n); 191} 192 193/* 194 * Send a single message to the TCP at address specified by 195 * the given TCP/IP header. If m == 0, then we make a copy 196 * of the tcpiphdr at ti and send directly to the addressed host. 197 * This is used to force keep alive messages out using the TCP 198 * template for a connection tp->t_template. If flags are given 199 * then we send a message back to the TCP which originated the 200 * segment ti, and discard the mbuf containing it and any other 201 * attached mbufs. 202 * 203 * In any case the ack and sequence number of the transmitted 204 * segment are as specified by the parameters. 205 * 206 * NOTE: If m != NULL, then ti must point to *inside* the mbuf. 207 */ 208void 209tcp_respond(tp, ti, m, ack, seq, flags) 210 struct tcpcb *tp; 211 register struct tcpiphdr *ti; 212 register struct mbuf *m; 213 tcp_seq ack, seq; 214 int flags; 215{ 216 register int tlen; 217 int win = 0; 218 struct route *ro = 0; 219 struct route sro; 220 221 if (tp) { 222 if (!(flags & TH_RST)) 223 win = sbspace(&tp->t_inpcb->inp_socket->so_rcv); 224 ro = &tp->t_inpcb->inp_route; 225 } else { 226 ro = &sro; 227 bzero(ro, sizeof *ro); 228 } 229 if (m == 0) { 230 m = m_gethdr(M_DONTWAIT, MT_HEADER); 231 if (m == NULL) 232 return; 233#ifdef TCP_COMPAT_42 234 tlen = 1; 235#else 236 tlen = 0; 237#endif 238 m->m_data += max_linkhdr; 239 *mtod(m, struct tcpiphdr *) = *ti; 240 ti = mtod(m, struct tcpiphdr *); 241 flags = TH_ACK; 242 } else { 243 m_freem(m->m_next); 244 m->m_next = 0; 245 m->m_data = (caddr_t)ti; 246 m->m_len = sizeof (struct tcpiphdr); 247 tlen = 0; 248#define xchg(a,b,type) { type t; t=a; a=b; b=t; } 249 xchg(ti->ti_dst.s_addr, ti->ti_src.s_addr, n_long); 250 xchg(ti->ti_dport, ti->ti_sport, n_short); 251#undef xchg 252 } 253 ti->ti_len = htons((u_short)(sizeof (struct tcphdr) + tlen)); 254 tlen += sizeof (struct tcpiphdr); 255 m->m_len = tlen; 256 m->m_pkthdr.len = tlen; 257 m->m_pkthdr.rcvif = (struct ifnet *) 0; 258 bzero(ti->ti_x1, sizeof(ti->ti_x1)); 259 ti->ti_seq = htonl(seq); 260 ti->ti_ack = htonl(ack); 261 ti->ti_x2 = 0; 262 ti->ti_off = sizeof (struct tcphdr) >> 2; 263 ti->ti_flags = flags; 264 if (tp) 265 ti->ti_win = htons((u_short) (win >> tp->rcv_scale)); 266 else 267 ti->ti_win = htons((u_short)win); 268 ti->ti_urp = 0; 269 ti->ti_sum = 0; 270 ti->ti_sum = in_cksum(m, tlen); 271 ((struct ip *)ti)->ip_len = tlen; 272 ((struct ip *)ti)->ip_ttl = ip_defttl; 273#ifdef TCPDEBUG 274 if (tp == NULL || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 275 tcp_trace(TA_OUTPUT, 0, tp, ti, 0); 276#endif 277 (void) ip_output(m, NULL, ro, 0, NULL); 278 if (ro == &sro && ro->ro_rt) { 279 RTFREE(ro->ro_rt); 280 } 281} 282 283/* 284 * Create a new TCP control block, making an 285 * empty reassembly queue and hooking it to the argument 286 * protocol control block. The `inp' parameter must have 287 * come from the zone allocator set up in tcp_init(). 288 */ 289struct tcpcb * 290tcp_newtcpcb(inp) 291 struct inpcb *inp; 292{ 293 struct inp_tp *it; 294 register struct tcpcb *tp; 295 296 it = (struct inp_tp *)inp; 297 tp = &it->tcb; 298 bzero((char *) tp, sizeof(struct tcpcb)); 299 tp->t_segq = NULL; 300 tp->t_maxseg = tp->t_maxopd = tcp_mssdflt; 301 302 if (tcp_do_rfc1323) 303 tp->t_flags = (TF_REQ_SCALE|TF_REQ_TSTMP); 304 if (tcp_do_rfc1644) 305 tp->t_flags |= TF_REQ_CC; 306 tp->t_inpcb = inp; /* XXX */ 307 /* 308 * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no 309 * rtt estimate. Set rttvar so that srtt + 4 * rttvar gives 310 * reasonable initial retransmit time. 311 */ 312 tp->t_srtt = TCPTV_SRTTBASE; 313 tp->t_rttvar = ((TCPTV_RTOBASE - TCPTV_SRTTBASE) << TCP_RTTVAR_SHIFT) / 4; 314 tp->t_rttmin = TCPTV_MIN; 315 tp->t_rxtcur = TCPTV_RTOBASE; 316 tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 317 tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT; 318 inp->inp_ip_ttl = ip_defttl; 319 inp->inp_ppcb = (caddr_t)tp; 320 return (tp); /* XXX */ 321} 322 323/* 324 * Drop a TCP connection, reporting 325 * the specified error. If connection is synchronized, 326 * then send a RST to peer. 327 */ 328struct tcpcb * 329tcp_drop(tp, errno) 330 register struct tcpcb *tp; 331 int errno; 332{ 333 struct socket *so = tp->t_inpcb->inp_socket; 334 335 if (TCPS_HAVERCVDSYN(tp->t_state)) { 336 tp->t_state = TCPS_CLOSED; 337 (void) tcp_output(tp); 338 tcpstat.tcps_drops++; 339 } else 340 tcpstat.tcps_conndrops++; 341 if (errno == ETIMEDOUT && tp->t_softerror) 342 errno = tp->t_softerror; 343 so->so_error = errno; 344 return (tcp_close(tp)); 345} 346 347/* 348 * Close a TCP control block: 349 * discard all space held by the tcp 350 * discard internet protocol block 351 * wake up any sleepers 352 */ 353struct tcpcb * 354tcp_close(tp) 355 register struct tcpcb *tp; 356{ 357 register struct mbuf *q; 358 register struct mbuf *nq; 359 struct inpcb *inp = tp->t_inpcb; 360 struct socket *so = inp->inp_socket; 361 register struct rtentry *rt; 362 int dosavessthresh; 363 364 /* 365 * If we got enough samples through the srtt filter, 366 * save the rtt and rttvar in the routing entry. 367 * 'Enough' is arbitrarily defined as the 16 samples. 368 * 16 samples is enough for the srtt filter to converge 369 * to within 5% of the correct value; fewer samples and 370 * we could save a very bogus rtt. 371 * 372 * Don't update the default route's characteristics and don't 373 * update anything that the user "locked". 374 */ 375 if (tp->t_rttupdated >= 16 && 376 (rt = inp->inp_route.ro_rt) && 377 ((struct sockaddr_in *)rt_key(rt))->sin_addr.s_addr != INADDR_ANY) { 378 register u_long i = 0; 379 380 if ((rt->rt_rmx.rmx_locks & RTV_RTT) == 0) { 381 i = tp->t_srtt * 382 (RTM_RTTUNIT / (PR_SLOWHZ * TCP_RTT_SCALE)); 383 if (rt->rt_rmx.rmx_rtt && i) 384 /* 385 * filter this update to half the old & half 386 * the new values, converting scale. 387 * See route.h and tcp_var.h for a 388 * description of the scaling constants. 389 */ 390 rt->rt_rmx.rmx_rtt = 391 (rt->rt_rmx.rmx_rtt + i) / 2; 392 else 393 rt->rt_rmx.rmx_rtt = i; 394 tcpstat.tcps_cachedrtt++; 395 } 396 if ((rt->rt_rmx.rmx_locks & RTV_RTTVAR) == 0) { 397 i = tp->t_rttvar * 398 (RTM_RTTUNIT / (PR_SLOWHZ * TCP_RTTVAR_SCALE)); 399 if (rt->rt_rmx.rmx_rttvar && i) 400 rt->rt_rmx.rmx_rttvar = 401 (rt->rt_rmx.rmx_rttvar + i) / 2; 402 else 403 rt->rt_rmx.rmx_rttvar = i; 404 tcpstat.tcps_cachedrttvar++; 405 } 406 /* 407 * The old comment here said: 408 * update the pipelimit (ssthresh) if it has been updated 409 * already or if a pipesize was specified & the threshhold 410 * got below half the pipesize. I.e., wait for bad news 411 * before we start updating, then update on both good 412 * and bad news. 413 * 414 * But we want to save the ssthresh even if no pipesize is 415 * specified explicitly in the route, because such 416 * connections still have an implicit pipesize specified 417 * by the global tcp_sendspace. In the absence of a reliable 418 * way to calculate the pipesize, it will have to do. 419 */ 420 i = tp->snd_ssthresh; 421 if (rt->rt_rmx.rmx_sendpipe != 0) 422 dosavessthresh = (i < rt->rt_rmx.rmx_sendpipe / 2); 423 else 424 dosavessthresh = (i < so->so_snd.sb_hiwat / 2); 425 if (((rt->rt_rmx.rmx_locks & RTV_SSTHRESH) == 0 && 426 i != 0 && rt->rt_rmx.rmx_ssthresh != 0) 427 || dosavessthresh) { 428 /* 429 * convert the limit from user data bytes to 430 * packets then to packet data bytes. 431 */ 432 i = (i + tp->t_maxseg / 2) / tp->t_maxseg; 433 if (i < 2) 434 i = 2; 435 i *= (u_long)(tp->t_maxseg + sizeof (struct tcpiphdr)); 436 if (rt->rt_rmx.rmx_ssthresh) 437 rt->rt_rmx.rmx_ssthresh = 438 (rt->rt_rmx.rmx_ssthresh + i) / 2; 439 else 440 rt->rt_rmx.rmx_ssthresh = i; 441 tcpstat.tcps_cachedssthresh++; 442 } 443 } 444 /* free the reassembly queue, if any */ 445 for (q = tp->t_segq; q; q = nq) { 446 nq = q->m_nextpkt; 447 tp->t_segq = nq; 448 m_freem(q); 449 } 450 if (tp->t_template) 451 (void) m_free(dtom(tp->t_template)); 452 inp->inp_ppcb = NULL; 453 soisdisconnected(so); 454 in_pcbdetach(inp); 455 tcpstat.tcps_closed++; 456 return ((struct tcpcb *)0); 457} 458 459void 460tcp_drain() 461{ 462 463} 464 465/* 466 * Notify a tcp user of an asynchronous error; 467 * store error as soft error, but wake up user 468 * (for now, won't do anything until can select for soft error). 469 */ 470static void 471tcp_notify(inp, error) 472 struct inpcb *inp; 473 int error; 474{ 475 register struct tcpcb *tp = (struct tcpcb *)inp->inp_ppcb; 476 register struct socket *so = inp->inp_socket; 477 478 /* 479 * Ignore some errors if we are hooked up. 480 * If connection hasn't completed, has retransmitted several times, 481 * and receives a second error, give up now. This is better 482 * than waiting a long time to establish a connection that 483 * can never complete. 484 */ 485 if (tp->t_state == TCPS_ESTABLISHED && 486 (error == EHOSTUNREACH || error == ENETUNREACH || 487 error == EHOSTDOWN)) { 488 return; 489 } else if (tp->t_state < TCPS_ESTABLISHED && tp->t_rxtshift > 3 && 490 tp->t_softerror) 491 so->so_error = error; 492 else 493 tp->t_softerror = error; 494 wakeup((caddr_t) &so->so_timeo); 495 sorwakeup(so); 496 sowwakeup(so); 497} 498 499static int 500tcp_pcblist SYSCTL_HANDLER_ARGS 501{ 502 int error, i, n, s; 503 struct inpcb *inp, **inp_list; 504 inp_gen_t gencnt; 505 struct xinpgen xig; 506 507 /* 508 * The process of preparing the TCB list is too time-consuming and 509 * resource-intensive to repeat twice on every request. 510 */ 511 if (req->oldptr == 0) { 512 n = tcbinfo.ipi_count; 513 req->oldidx = 2 * (sizeof xig) 514 + (n + n/8) * sizeof(struct xtcpcb); 515 return 0; 516 } 517 518 if (req->newptr != 0) 519 return EPERM; 520 521 /* 522 * OK, now we're committed to doing something. 523 */ 524 s = splnet(); 525 gencnt = tcbinfo.ipi_gencnt; 526 n = tcbinfo.ipi_count; 527 splx(s); 528 529 xig.xig_len = sizeof xig; 530 xig.xig_count = n; 531 xig.xig_gen = gencnt; 532 xig.xig_sogen = so_gencnt; 533 error = SYSCTL_OUT(req, &xig, sizeof xig); 534 if (error) 535 return error; 536 537 inp_list = malloc(n * sizeof *inp_list, M_TEMP, M_WAITOK); 538 if (inp_list == 0) 539 return ENOMEM; 540 541 s = splnet(); 542 for (inp = tcbinfo.listhead->lh_first, i = 0; inp && i < n; 543 inp = inp->inp_list.le_next) { 544 if (inp->inp_gencnt <= gencnt && !prison_xinpcb(req->p, inp)) 545 inp_list[i++] = inp; 546 } 547 splx(s); 548 n = i; 549 550 error = 0; 551 for (i = 0; i < n; i++) { 552 inp = inp_list[i]; 553 if (inp->inp_gencnt <= gencnt) { 554 struct xtcpcb xt; 555 xt.xt_len = sizeof xt; 556 /* XXX should avoid extra copy */ 557 bcopy(inp, &xt.xt_inp, sizeof *inp); 558 bcopy(inp->inp_ppcb, &xt.xt_tp, sizeof xt.xt_tp); 559 if (inp->inp_socket) 560 sotoxsocket(inp->inp_socket, &xt.xt_socket); 561 error = SYSCTL_OUT(req, &xt, sizeof xt); 562 } 563 } 564 if (!error) { 565 /* 566 * Give the user an updated idea of our state. 567 * If the generation differs from what we told 568 * her before, she knows that something happened 569 * while we were processing this request, and it 570 * might be necessary to retry. 571 */ 572 s = splnet(); 573 xig.xig_gen = tcbinfo.ipi_gencnt; 574 xig.xig_sogen = so_gencnt; 575 xig.xig_count = tcbinfo.ipi_count; 576 splx(s); 577 error = SYSCTL_OUT(req, &xig, sizeof xig); 578 } 579 free(inp_list, M_TEMP); 580 return error; 581} 582 583SYSCTL_PROC(_net_inet_tcp, TCPCTL_PCBLIST, pcblist, CTLFLAG_RD, 0, 0, 584 tcp_pcblist, "S,xtcpcb", "List of active TCP connections"); 585 586void 587tcp_ctlinput(cmd, sa, vip) 588 int cmd; 589 struct sockaddr *sa; 590 void *vip; 591{ 592 register struct ip *ip = vip; 593 register struct tcphdr *th; 594 void (*notify) __P((struct inpcb *, int)) = tcp_notify; 595 596 if (cmd == PRC_QUENCH) 597 notify = tcp_quench; 598 else if (cmd == PRC_MSGSIZE) 599 notify = tcp_mtudisc; 600 else if (!PRC_IS_REDIRECT(cmd) && 601 ((unsigned)cmd > PRC_NCMDS || inetctlerrmap[cmd] == 0)) 602 return; 603 if (ip) { 604 th = (struct tcphdr *)((caddr_t)ip 605 + (IP_VHL_HL(ip->ip_vhl) << 2)); 606 in_pcbnotify(&tcb, sa, th->th_dport, ip->ip_src, th->th_sport, 607 cmd, notify); 608 } else 609 in_pcbnotify(&tcb, sa, 0, zeroin_addr, 0, cmd, notify); 610} 611 612/* 613 * When a source quench is received, close congestion window 614 * to one segment. We will gradually open it again as we proceed. 615 */ 616void 617tcp_quench(inp, errno) 618 struct inpcb *inp; 619 int errno; 620{ 621 struct tcpcb *tp = intotcpcb(inp); 622 623 if (tp) 624 tp->snd_cwnd = tp->t_maxseg; 625} 626 627/* 628 * When `need fragmentation' ICMP is received, update our idea of the MSS 629 * based on the new value in the route. Also nudge TCP to send something, 630 * since we know the packet we just sent was dropped. 631 * This duplicates some code in the tcp_mss() function in tcp_input.c. 632 */ 633void 634tcp_mtudisc(inp, errno) 635 struct inpcb *inp; 636 int errno; 637{ 638 struct tcpcb *tp = intotcpcb(inp); 639 struct rtentry *rt; 640 struct rmxp_tao *taop; 641 struct socket *so = inp->inp_socket; 642 int offered; 643 int mss; 644 645 if (tp) { 646 rt = tcp_rtlookup(inp); 647 if (!rt || !rt->rt_rmx.rmx_mtu) { 648 tp->t_maxopd = tp->t_maxseg = tcp_mssdflt; 649 return; 650 } 651 taop = rmx_taop(rt->rt_rmx); 652 offered = taop->tao_mssopt; 653 mss = rt->rt_rmx.rmx_mtu - sizeof(struct tcpiphdr); 654 if (offered) 655 mss = min(mss, offered); 656 /* 657 * XXX - The above conditional probably violates the TCP 658 * spec. The problem is that, since we don't know the 659 * other end's MSS, we are supposed to use a conservative 660 * default. But, if we do that, then MTU discovery will 661 * never actually take place, because the conservative 662 * default is much less than the MTUs typically seen 663 * on the Internet today. For the moment, we'll sweep 664 * this under the carpet. 665 * 666 * The conservative default might not actually be a problem 667 * if the only case this occurs is when sending an initial 668 * SYN with options and data to a host we've never talked 669 * to before. Then, they will reply with an MSS value which 670 * will get recorded and the new parameters should get 671 * recomputed. For Further Study. 672 */ 673 if (tp->t_maxopd <= mss) 674 return; 675 tp->t_maxopd = mss; 676 677 if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP && 678 (tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP) 679 mss -= TCPOLEN_TSTAMP_APPA; 680 if ((tp->t_flags & (TF_REQ_CC|TF_NOOPT)) == TF_REQ_CC && 681 (tp->t_flags & TF_RCVD_CC) == TF_RCVD_CC) 682 mss -= TCPOLEN_CC_APPA; 683#if (MCLBYTES & (MCLBYTES - 1)) == 0 684 if (mss > MCLBYTES) 685 mss &= ~(MCLBYTES-1); 686#else 687 if (mss > MCLBYTES) 688 mss = mss / MCLBYTES * MCLBYTES; 689#endif 690 if (so->so_snd.sb_hiwat < mss) 691 mss = so->so_snd.sb_hiwat; 692 693 tp->t_maxseg = mss; 694 695 tcpstat.tcps_mturesent++; 696 tp->t_rtt = 0; 697 tp->snd_nxt = tp->snd_una; 698 tcp_output(tp); 699 } 700} 701 702/* 703 * Look-up the routing entry to the peer of this inpcb. If no route 704 * is found and it cannot be allocated the return NULL. This routine 705 * is called by TCP routines that access the rmx structure and by tcp_mss 706 * to get the interface MTU. 707 */ 708struct rtentry * 709tcp_rtlookup(inp) 710 struct inpcb *inp; 711{ 712 struct route *ro; 713 struct rtentry *rt; 714 715 ro = &inp->inp_route; 716 rt = ro->ro_rt; 717 if (rt == NULL || !(rt->rt_flags & RTF_UP)) { 718 /* No route yet, so try to acquire one */ 719 if (inp->inp_faddr.s_addr != INADDR_ANY) { 720 ro->ro_dst.sa_family = AF_INET; 721 ro->ro_dst.sa_len = sizeof(ro->ro_dst); 722 ((struct sockaddr_in *) &ro->ro_dst)->sin_addr = 723 inp->inp_faddr; 724 rtalloc(ro); 725 rt = ro->ro_rt; 726 } 727 } 728 return rt; 729} 730 731/* 732 * Return a pointer to the cached information about the remote host. 733 * The cached information is stored in the protocol specific part of 734 * the route metrics. 735 */ 736struct rmxp_tao * 737tcp_gettaocache(inp) 738 struct inpcb *inp; 739{ 740 struct rtentry *rt = tcp_rtlookup(inp); 741 742 /* Make sure this is a host route and is up. */ 743 if (rt == NULL || 744 (rt->rt_flags & (RTF_UP|RTF_HOST)) != (RTF_UP|RTF_HOST)) 745 return NULL; 746 747 return rmx_taop(rt->rt_rmx); 748} 749 750/* 751 * Clear all the TAO cache entries, called from tcp_init. 752 * 753 * XXX 754 * This routine is just an empty one, because we assume that the routing 755 * routing tables are initialized at the same time when TCP, so there is 756 * nothing in the cache left over. 757 */ 758static void 759tcp_cleartaocache() 760{ 761} 762