1 /* $NetBSD: tcp_subr.c,v 1.38 1998/01/05 10:32:09 thorpej Exp $ */ 2 3 /* 4 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed by the University of 18 * California, Berkeley and its contributors. 19 * 4. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 * 35 * @(#)tcp_subr.c 8.2 (Berkeley) 5/24/95 36 */ 37 38 #include "rnd.h" 39 40 #include <sys/param.h> 41 #include <sys/proc.h> 42 #include <sys/systm.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 #include <sys/errno.h> 49 #include <sys/kernel.h> 50 #if NRND > 0 51 #include <sys/rnd.h> 52 #endif 53 54 #include <net/route.h> 55 #include <net/if.h> 56 57 #include <netinet/in.h> 58 #include <netinet/in_systm.h> 59 #include <netinet/ip.h> 60 #include <netinet/in_pcb.h> 61 #include <netinet/ip_var.h> 62 #include <netinet/ip_icmp.h> 63 #include <netinet/tcp.h> 64 #include <netinet/tcp_fsm.h> 65 #include <netinet/tcp_seq.h> 66 #include <netinet/tcp_timer.h> 67 #include <netinet/tcp_var.h> 68 #include <netinet/tcpip.h> 69 70 /* patchable/settable parameters for tcp */ 71 int tcp_mssdflt = TCP_MSS; 72 int tcp_rttdflt = TCPTV_SRTTDFLT / PR_SLOWHZ; 73 int tcp_do_rfc1323 = 1; 74 int tcp_init_win = 1; 75 76 #ifndef TCBHASHSIZE 77 #define TCBHASHSIZE 128 78 #endif 79 int tcbhashsize = TCBHASHSIZE; 80 81 int tcp_freeq __P((struct tcpcb *)); 82 83 /* 84 * Tcp initialization 85 */ 86 void 87 tcp_init() 88 { 89 90 in_pcbinit(&tcbtable, tcbhashsize, tcbhashsize); 91 LIST_INIT(&tcp_delacks); 92 if (max_protohdr < sizeof(struct tcpiphdr)) 93 max_protohdr = sizeof(struct tcpiphdr); 94 if (max_linkhdr + sizeof(struct tcpiphdr) > MHLEN) 95 panic("tcp_init"); 96 } 97 98 /* 99 * Create template to be used to send tcp packets on a connection. 100 * Call after host entry created, allocates an mbuf and fills 101 * in a skeletal tcp/ip header, minimizing the amount of work 102 * necessary when the connection is used. 103 */ 104 struct tcpiphdr * 105 tcp_template(tp) 106 struct tcpcb *tp; 107 { 108 register struct inpcb *inp = tp->t_inpcb; 109 register struct tcpiphdr *n; 110 111 if ((n = tp->t_template) == 0) { 112 MALLOC(n, struct tcpiphdr *, sizeof (struct tcpiphdr), 113 M_MBUF, M_NOWAIT); 114 if (n == NULL) 115 return (0); 116 } 117 bzero(n->ti_x1, sizeof n->ti_x1); 118 n->ti_pr = IPPROTO_TCP; 119 n->ti_len = htons(sizeof (struct tcpiphdr) - sizeof (struct ip)); 120 n->ti_src = inp->inp_laddr; 121 n->ti_dst = inp->inp_faddr; 122 n->ti_sport = inp->inp_lport; 123 n->ti_dport = inp->inp_fport; 124 n->ti_seq = 0; 125 n->ti_ack = 0; 126 n->ti_x2 = 0; 127 n->ti_off = 5; 128 n->ti_flags = 0; 129 n->ti_win = 0; 130 n->ti_sum = 0; 131 n->ti_urp = 0; 132 return (n); 133 } 134 135 /* 136 * Send a single message to the TCP at address specified by 137 * the given TCP/IP header. If m == 0, then we make a copy 138 * of the tcpiphdr at ti and send directly to the addressed host. 139 * This is used to force keep alive messages out using the TCP 140 * template for a connection tp->t_template. If flags are given 141 * then we send a message back to the TCP which originated the 142 * segment ti, and discard the mbuf containing it and any other 143 * attached mbufs. 144 * 145 * In any case the ack and sequence number of the transmitted 146 * segment are as specified by the parameters. 147 */ 148 int 149 tcp_respond(tp, ti, m, ack, seq, flags) 150 struct tcpcb *tp; 151 register struct tcpiphdr *ti; 152 register struct mbuf *m; 153 tcp_seq ack, seq; 154 int flags; 155 { 156 register int tlen; 157 int win = 0; 158 struct route *ro = 0; 159 160 if (tp) { 161 win = sbspace(&tp->t_inpcb->inp_socket->so_rcv); 162 ro = &tp->t_inpcb->inp_route; 163 } 164 if (m == 0) { 165 m = m_gethdr(M_DONTWAIT, MT_HEADER); 166 if (m == NULL) 167 return (ENOBUFS); 168 #ifdef TCP_COMPAT_42 169 tlen = 1; 170 #else 171 tlen = 0; 172 #endif 173 m->m_data += max_linkhdr; 174 *mtod(m, struct tcpiphdr *) = *ti; 175 ti = mtod(m, struct tcpiphdr *); 176 flags = TH_ACK; 177 } else { 178 m_freem(m->m_next); 179 m->m_next = 0; 180 m->m_data = (caddr_t)ti; 181 m->m_len = sizeof (struct tcpiphdr); 182 tlen = 0; 183 #define xchg(a,b,type) { type t; t=a; a=b; b=t; } 184 xchg(ti->ti_dst.s_addr, ti->ti_src.s_addr, u_int32_t); 185 xchg(ti->ti_dport, ti->ti_sport, u_int16_t); 186 #undef xchg 187 } 188 bzero(ti->ti_x1, sizeof ti->ti_x1); 189 ti->ti_seq = htonl(seq); 190 ti->ti_ack = htonl(ack); 191 ti->ti_x2 = 0; 192 if ((flags & TH_SYN) == 0) { 193 if (tp) 194 ti->ti_win = htons((u_int16_t) (win >> tp->rcv_scale)); 195 else 196 ti->ti_win = htons((u_int16_t)win); 197 ti->ti_off = sizeof (struct tcphdr) >> 2; 198 tlen += sizeof (struct tcphdr); 199 } else 200 tlen += ti->ti_off << 2; 201 ti->ti_len = htons((u_int16_t)tlen); 202 tlen += sizeof (struct ip); 203 m->m_len = tlen; 204 m->m_pkthdr.len = tlen; 205 m->m_pkthdr.rcvif = (struct ifnet *) 0; 206 ti->ti_flags = flags; 207 ti->ti_urp = 0; 208 ti->ti_sum = 0; 209 ti->ti_sum = in_cksum(m, tlen); 210 ((struct ip *)ti)->ip_len = tlen; 211 ((struct ip *)ti)->ip_ttl = ip_defttl; 212 return ip_output(m, NULL, ro, 0, NULL); 213 } 214 215 /* 216 * Create a new TCP control block, making an 217 * empty reassembly queue and hooking it to the argument 218 * protocol control block. 219 */ 220 struct tcpcb * 221 tcp_newtcpcb(inp) 222 struct inpcb *inp; 223 { 224 register struct tcpcb *tp; 225 226 tp = malloc(sizeof(*tp), M_PCB, M_NOWAIT); 227 if (tp == NULL) 228 return ((struct tcpcb *)0); 229 bzero((caddr_t)tp, sizeof(struct tcpcb)); 230 LIST_INIT(&tp->segq); 231 tp->t_peermss = tcp_mssdflt; 232 tp->t_ourmss = tcp_mssdflt; 233 tp->t_segsz = tcp_mssdflt; 234 235 tp->t_flags = tcp_do_rfc1323 ? (TF_REQ_SCALE|TF_REQ_TSTMP) : 0; 236 tp->t_inpcb = inp; 237 /* 238 * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no 239 * rtt estimate. Set rttvar so that srtt + 2 * rttvar gives 240 * reasonable initial retransmit time. 241 */ 242 tp->t_srtt = TCPTV_SRTTBASE; 243 tp->t_rttvar = tcp_rttdflt * PR_SLOWHZ << (TCP_RTTVAR_SHIFT + 2 - 1); 244 tp->t_rttmin = TCPTV_MIN; 245 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), 246 TCPTV_MIN, TCPTV_REXMTMAX); 247 tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT; 248 tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT; 249 inp->inp_ip.ip_ttl = ip_defttl; 250 inp->inp_ppcb = (caddr_t)tp; 251 return (tp); 252 } 253 254 /* 255 * Drop a TCP connection, reporting 256 * the specified error. If connection is synchronized, 257 * then send a RST to peer. 258 */ 259 struct tcpcb * 260 tcp_drop(tp, errno) 261 register struct tcpcb *tp; 262 int errno; 263 { 264 struct socket *so = tp->t_inpcb->inp_socket; 265 266 if (TCPS_HAVERCVDSYN(tp->t_state)) { 267 tp->t_state = TCPS_CLOSED; 268 (void) tcp_output(tp); 269 tcpstat.tcps_drops++; 270 } else 271 tcpstat.tcps_conndrops++; 272 if (errno == ETIMEDOUT && tp->t_softerror) 273 errno = tp->t_softerror; 274 so->so_error = errno; 275 return (tcp_close(tp)); 276 } 277 278 /* 279 * Close a TCP control block: 280 * discard all space held by the tcp 281 * discard internet protocol block 282 * wake up any sleepers 283 */ 284 struct tcpcb * 285 tcp_close(tp) 286 register struct tcpcb *tp; 287 { 288 struct inpcb *inp = tp->t_inpcb; 289 struct socket *so = inp->inp_socket; 290 #ifdef RTV_RTT 291 register struct rtentry *rt; 292 293 /* 294 * If we sent enough data to get some meaningful characteristics, 295 * save them in the routing entry. 'Enough' is arbitrarily 296 * defined as the sendpipesize (default 4K) * 16. This would 297 * give us 16 rtt samples assuming we only get one sample per 298 * window (the usual case on a long haul net). 16 samples is 299 * enough for the srtt filter to converge to within 5% of the correct 300 * value; fewer samples and we could save a very bogus rtt. 301 * 302 * Don't update the default route's characteristics and don't 303 * update anything that the user "locked". 304 */ 305 if (SEQ_LT(tp->iss + so->so_snd.sb_hiwat * 16, tp->snd_max) && 306 (rt = inp->inp_route.ro_rt) && 307 !in_nullhost(satosin(rt_key(rt))->sin_addr)) { 308 register u_long i = 0; 309 310 if ((rt->rt_rmx.rmx_locks & RTV_RTT) == 0) { 311 i = tp->t_srtt * 312 ((RTM_RTTUNIT / PR_SLOWHZ) >> (TCP_RTT_SHIFT + 2)); 313 if (rt->rt_rmx.rmx_rtt && i) 314 /* 315 * filter this update to half the old & half 316 * the new values, converting scale. 317 * See route.h and tcp_var.h for a 318 * description of the scaling constants. 319 */ 320 rt->rt_rmx.rmx_rtt = 321 (rt->rt_rmx.rmx_rtt + i) / 2; 322 else 323 rt->rt_rmx.rmx_rtt = i; 324 } 325 if ((rt->rt_rmx.rmx_locks & RTV_RTTVAR) == 0) { 326 i = tp->t_rttvar * 327 ((RTM_RTTUNIT / PR_SLOWHZ) >> (TCP_RTTVAR_SHIFT + 2)); 328 if (rt->rt_rmx.rmx_rttvar && i) 329 rt->rt_rmx.rmx_rttvar = 330 (rt->rt_rmx.rmx_rttvar + i) / 2; 331 else 332 rt->rt_rmx.rmx_rttvar = i; 333 } 334 /* 335 * update the pipelimit (ssthresh) if it has been updated 336 * already or if a pipesize was specified & the threshhold 337 * got below half the pipesize. I.e., wait for bad news 338 * before we start updating, then update on both good 339 * and bad news. 340 */ 341 if (((rt->rt_rmx.rmx_locks & RTV_SSTHRESH) == 0 && 342 (i = tp->snd_ssthresh) && rt->rt_rmx.rmx_ssthresh) || 343 i < (rt->rt_rmx.rmx_sendpipe / 2)) { 344 /* 345 * convert the limit from user data bytes to 346 * packets then to packet data bytes. 347 */ 348 i = (i + tp->t_segsz / 2) / tp->t_segsz; 349 if (i < 2) 350 i = 2; 351 i *= (u_long)(tp->t_segsz + sizeof (struct tcpiphdr)); 352 if (rt->rt_rmx.rmx_ssthresh) 353 rt->rt_rmx.rmx_ssthresh = 354 (rt->rt_rmx.rmx_ssthresh + i) / 2; 355 else 356 rt->rt_rmx.rmx_ssthresh = i; 357 } 358 } 359 #endif /* RTV_RTT */ 360 /* free the reassembly queue, if any */ 361 (void) tcp_freeq(tp); 362 363 if (tp->t_template) 364 FREE(tp->t_template, M_MBUF); 365 free(tp, M_PCB); 366 inp->inp_ppcb = 0; 367 soisdisconnected(so); 368 in_pcbdetach(inp); 369 tcpstat.tcps_closed++; 370 return ((struct tcpcb *)0); 371 } 372 373 int 374 tcp_freeq(tp) 375 struct tcpcb *tp; 376 { 377 register struct ipqent *qe; 378 int rv = 0; 379 380 while ((qe = tp->segq.lh_first) != NULL) { 381 LIST_REMOVE(qe, ipqe_q); 382 m_freem(qe->ipqe_m); 383 FREE(qe, M_IPQ); 384 rv = 1; 385 } 386 return (rv); 387 } 388 389 /* 390 * Protocol drain routine. Called when memory is in short supply. 391 */ 392 void 393 tcp_drain() 394 { 395 register struct inpcb *inp; 396 register struct tcpcb *tp; 397 398 /* 399 * Free the sequence queue of all TCP connections. 400 */ 401 inp = tcbtable.inpt_queue.cqh_first; 402 if (inp) /* XXX */ 403 for (; inp != (struct inpcb *)&tcbtable.inpt_queue; 404 inp = inp->inp_queue.cqe_next) { 405 if ((tp = intotcpcb(inp)) != NULL) { 406 if (tcp_freeq(tp)) 407 tcpstat.tcps_connsdrained++; 408 } 409 } 410 } 411 412 /* 413 * Notify a tcp user of an asynchronous error; 414 * store error as soft error, but wake up user 415 * (for now, won't do anything until can select for soft error). 416 */ 417 void 418 tcp_notify(inp, error) 419 struct inpcb *inp; 420 int error; 421 { 422 register struct tcpcb *tp = (struct tcpcb *)inp->inp_ppcb; 423 register struct socket *so = inp->inp_socket; 424 425 /* 426 * Ignore some errors if we are hooked up. 427 * If connection hasn't completed, has retransmitted several times, 428 * and receives a second error, give up now. This is better 429 * than waiting a long time to establish a connection that 430 * can never complete. 431 */ 432 if (tp->t_state == TCPS_ESTABLISHED && 433 (error == EHOSTUNREACH || error == ENETUNREACH || 434 error == EHOSTDOWN)) { 435 return; 436 } else if (TCPS_HAVEESTABLISHED(tp->t_state) == 0 && 437 tp->t_rxtshift > 3 && tp->t_softerror) 438 so->so_error = error; 439 else 440 tp->t_softerror = error; 441 wakeup((caddr_t) &so->so_timeo); 442 sorwakeup(so); 443 sowwakeup(so); 444 } 445 446 void * 447 tcp_ctlinput(cmd, sa, v) 448 int cmd; 449 struct sockaddr *sa; 450 register void *v; 451 { 452 register struct ip *ip = v; 453 register struct tcphdr *th; 454 extern int inetctlerrmap[]; 455 void (*notify) __P((struct inpcb *, int)) = tcp_notify; 456 int errno; 457 int nmatch; 458 459 if ((unsigned)cmd >= PRC_NCMDS) 460 return NULL; 461 errno = inetctlerrmap[cmd]; 462 if (cmd == PRC_QUENCH) 463 notify = tcp_quench; 464 else if (PRC_IS_REDIRECT(cmd)) 465 notify = in_rtchange, ip = 0; 466 else if (cmd == PRC_MSGSIZE && ip_mtudisc) 467 notify = tcp_mtudisc, ip = 0; 468 else if (cmd == PRC_HOSTDEAD) 469 ip = 0; 470 else if (errno == 0) 471 return NULL; 472 if (ip) { 473 th = (struct tcphdr *)((caddr_t)ip + (ip->ip_hl << 2)); 474 nmatch = in_pcbnotify(&tcbtable, satosin(sa)->sin_addr, 475 th->th_dport, ip->ip_src, th->th_sport, errno, notify); 476 if (nmatch == 0 && syn_cache_count && 477 (inetctlerrmap[cmd] == EHOSTUNREACH || 478 inetctlerrmap[cmd] == ENETUNREACH || 479 inetctlerrmap[cmd] == EHOSTDOWN)) 480 syn_cache_unreach(ip, th); 481 } else 482 (void)in_pcbnotifyall(&tcbtable, satosin(sa)->sin_addr, errno, 483 notify); 484 return NULL; 485 } 486 487 /* 488 * When a source quench is received, close congestion window 489 * to one segment. We will gradually open it again as we proceed. 490 */ 491 void 492 tcp_quench(inp, errno) 493 struct inpcb *inp; 494 int errno; 495 { 496 struct tcpcb *tp = intotcpcb(inp); 497 498 if (tp) 499 tp->snd_cwnd = tp->t_segsz; 500 } 501 502 /* 503 * On receipt of path MTU corrections, flush old route and replace it 504 * with the new one. Retransmit all unacknowledged packets, to ensure 505 * that all packets will be received. 506 */ 507 void 508 tcp_mtudisc(inp, errno) 509 struct inpcb *inp; 510 int errno; 511 { 512 struct tcpcb *tp = intotcpcb(inp); 513 struct rtentry *rt = in_pcbrtentry(inp); 514 515 if (tp != 0) { 516 if (rt != 0) { 517 /* 518 * If this was not a host route, remove and realloc. 519 */ 520 if ((rt->rt_flags & RTF_HOST) == 0) { 521 in_rtchange(inp, errno); 522 if ((rt = in_pcbrtentry(inp)) == 0) 523 return; 524 } 525 526 /* 527 * Slow start out of the error condition. We 528 * use the MTU because we know it's smaller 529 * than the previously transmitted segment. 530 */ 531 if (rt->rt_rmx.rmx_mtu != 0) 532 tp->snd_cwnd = 533 TCP_INITIAL_WINDOW(rt->rt_rmx.rmx_mtu); 534 } 535 536 /* 537 * Resend unacknowledged packets. 538 */ 539 tp->snd_nxt = tp->snd_una; 540 tcp_output(tp); 541 } 542 } 543 544 545 /* 546 * Compute the MSS to advertise to the peer. Called only during 547 * the 3-way handshake. If we are the server (peer initiated 548 * connection), we are called with the TCPCB for the listen 549 * socket. If we are the client (we initiated connection), we 550 * are called witht he TCPCB for the actual connection. 551 */ 552 int 553 tcp_mss_to_advertise(tp) 554 const struct tcpcb *tp; 555 { 556 extern u_long in_maxmtu; 557 struct inpcb *inp; 558 struct socket *so; 559 int mss; 560 561 inp = tp->t_inpcb; 562 so = inp->inp_socket; 563 564 /* 565 * In order to avoid defeating path MTU discovery on the peer, 566 * we advertise the max MTU of all attached networks as our MSS, 567 * per RFC 1191, section 3.1. 568 * 569 * XXX Should we allow room for the timestamp option if 570 * XXX rfc1323 is enabled? 571 */ 572 mss = in_maxmtu - sizeof(struct tcpiphdr); 573 574 return (mss); 575 } 576 577 /* 578 * Set connection variables based on the peer's advertised MSS. 579 * We are passed the TCPCB for the actual connection. If we 580 * are the server, we are called by the compressed state engine 581 * when the 3-way handshake is complete. If we are the client, 582 * we are called when we recieve the SYN,ACK from the server. 583 * 584 * NOTE: Our advertised MSS value must be initialized in the TCPCB 585 * before this routine is called! 586 */ 587 void 588 tcp_mss_from_peer(tp, offer) 589 struct tcpcb *tp; 590 int offer; 591 { 592 struct inpcb *inp = tp->t_inpcb; 593 struct socket *so = inp->inp_socket; 594 #if defined(RTV_SPIPE) || defined(RTV_SSTHRESH) 595 struct rtentry *rt = in_pcbrtentry(inp); 596 #endif 597 u_long bufsize; 598 int mss; 599 600 /* 601 * Assume our MSS is the MSS of the peer, unless they sent us 602 * an offer. Do not accept offers less than 32 bytes. 603 */ 604 mss = tp->t_ourmss; 605 if (offer) 606 mss = offer; 607 mss = max(mss, 32); /* sanity */ 608 609 /* 610 * If there's a pipesize, change the socket buffer to that size. 611 * Make the socket buffer an integral number of MSS units. If 612 * the MSS is larger than the socket buffer, artificially decrease 613 * the MSS. 614 */ 615 #ifdef RTV_SPIPE 616 if (rt != NULL && rt->rt_rmx.rmx_sendpipe != 0) 617 bufsize = rt->rt_rmx.rmx_sendpipe; 618 else 619 #endif 620 bufsize = so->so_snd.sb_hiwat; 621 if (bufsize < mss) 622 mss = bufsize; 623 else { 624 bufsize = roundup(bufsize, mss); 625 if (bufsize > sb_max) 626 bufsize = sb_max; 627 (void) sbreserve(&so->so_snd, bufsize); 628 } 629 tp->t_peermss = mss; 630 tp->t_segsz = mss; 631 632 /* Initialize the initial congestion window. */ 633 tp->snd_cwnd = TCP_INITIAL_WINDOW(mss); 634 635 #ifdef RTV_SSTHRESH 636 if (rt != NULL && rt->rt_rmx.rmx_ssthresh) { 637 /* 638 * There's some sort of gateway or interface buffer 639 * limit on the path. Use this to set the slow 640 * start threshold, but set the threshold to no less 641 * than 2 * MSS. 642 */ 643 tp->snd_ssthresh = max(2 * mss, rt->rt_rmx.rmx_ssthresh); 644 } 645 #endif 646 } 647 648 /* 649 * Processing necessary when a TCP connection is established. 650 */ 651 void 652 tcp_established(tp) 653 struct tcpcb *tp; 654 { 655 struct inpcb *inp = tp->t_inpcb; 656 struct socket *so = inp->inp_socket; 657 #ifdef RTV_RPIPE 658 struct rtentry *rt = in_pcbrtentry(inp); 659 #endif 660 u_long bufsize; 661 662 tp->t_state = TCPS_ESTABLISHED; 663 tp->t_timer[TCPT_KEEP] = tcp_keepidle; 664 665 #ifdef RTV_RPIPE 666 if (rt != NULL && rt->rt_rmx.rmx_recvpipe != 0) 667 bufsize = rt->rt_rmx.rmx_recvpipe; 668 else 669 #endif 670 bufsize = so->so_rcv.sb_hiwat; 671 if (bufsize > tp->t_ourmss) { 672 bufsize = roundup(bufsize, tp->t_ourmss); 673 if (bufsize > sb_max) 674 bufsize = sb_max; 675 (void) sbreserve(&so->so_rcv, bufsize); 676 } 677 } 678 679 /* 680 * Check if there's an initial rtt or rttvar. Convert from the 681 * route-table units to scaled multiples of the slow timeout timer. 682 * Called only during the 3-way handshake. 683 */ 684 void 685 tcp_rmx_rtt(tp) 686 struct tcpcb *tp; 687 { 688 #ifdef RTV_RTT 689 struct rtentry *rt; 690 int rtt; 691 692 if ((rt = in_pcbrtentry(tp->t_inpcb)) == NULL) 693 return; 694 695 if (tp->t_srtt == 0 && (rtt = rt->rt_rmx.rmx_rtt)) { 696 /* 697 * XXX The lock bit for MTU indicates that the value 698 * is also a minimum value; this is subject to time. 699 */ 700 if (rt->rt_rmx.rmx_locks & RTV_RTT) 701 tp->t_rttmin = rtt / (RTM_RTTUNIT / PR_SLOWHZ); 702 tp->t_srtt = rtt / 703 ((RTM_RTTUNIT / PR_SLOWHZ) >> (TCP_RTT_SHIFT + 2)); 704 if (rt->rt_rmx.rmx_rttvar) { 705 tp->t_rttvar = rt->rt_rmx.rmx_rttvar / 706 ((RTM_RTTUNIT / PR_SLOWHZ) >> 707 (TCP_RTTVAR_SHIFT + 2)); 708 } else { 709 /* Default variation is +- 1 rtt */ 710 tp->t_rttvar = 711 tp->t_srtt >> (TCP_RTT_SHIFT - TCP_RTTVAR_SHIFT); 712 } 713 TCPT_RANGESET(tp->t_rxtcur, 714 ((tp->t_srtt >> 2) + tp->t_rttvar) >> (1 + 2), 715 tp->t_rttmin, TCPTV_REXMTMAX); 716 } 717 #endif 718 } 719 720 tcp_seq tcp_iss_seq = 0; /* tcp initial seq # */ 721 722 /* 723 * Get a new sequence value given a tcp control block 724 */ 725 tcp_seq 726 tcp_new_iss(tp, len, addin) 727 void *tp; 728 u_long len; 729 tcp_seq addin; 730 { 731 tcp_seq tcp_iss; 732 733 /* 734 * add randomness about this connection, but do not estimate 735 * entropy from the timing, since the physical device driver would 736 * have done that for us. 737 */ 738 #if NRND > 0 739 if (tp != NULL) 740 rnd_add_data(NULL, tp, len, 0); 741 #endif 742 743 /* 744 * randomize. 745 */ 746 #if NRND > 0 747 rnd_extract_data(&tcp_iss, sizeof(tcp_iss), RND_EXTRACT_ANY); 748 #else 749 tcp_iss = random(); 750 #endif 751 752 /* 753 * If we were asked to add some amount to a known value, 754 * we will take a random value obtained above, mask off the upper 755 * bits, and add in the known value. We also add in a constant to 756 * ensure that we are at least a certain distance from the original 757 * value. 758 * 759 * This is used when an old connection is in timed wait 760 * and we have a new one coming in, for instance. 761 */ 762 if (addin != 0) { 763 #ifdef TCPISS_DEBUG 764 printf("Random %08x, ", tcp_iss); 765 #endif 766 tcp_iss &= TCP_ISS_RANDOM_MASK; 767 tcp_iss = tcp_iss + addin + TCP_ISSINCR; 768 tcp_iss_seq += TCP_ISSINCR; 769 tcp_iss += tcp_iss_seq; 770 #ifdef TCPISS_DEBUG 771 printf("Old ISS %08x, ISS %08x\n", addin, tcp_iss); 772 #endif 773 } else { 774 tcp_iss &= TCP_ISS_RANDOM_MASK; 775 tcp_iss_seq += TCP_ISSINCR; 776 tcp_iss += tcp_iss_seq; 777 #ifdef TCPISS_DEBUG 778 printf("ISS %08x\n", tcp_iss); 779 #endif 780 } 781 782 #ifdef TCP_COMPAT_42 783 /* 784 * limit it to the positive range for really old TCP implementations 785 */ 786 if ((int)tcp_iss < 0) 787 tcp_iss &= 0x7fffffff; /* XXX */ 788 #endif 789 790 return tcp_iss; 791 } 792