1 /* $NetBSD: tcp_output.c,v 1.62 2000/11/06 00:50:12 itojun Exp $ */ 2 3 /* 4 %%% portions-copyright-nrl-95 5 Portions of this software are Copyright 1995-1998 by Randall Atkinson, 6 Ronald Lee, Daniel McDonald, Bao Phan, and Chris Winters. All Rights 7 Reserved. All rights under this copyright have been assigned to the US 8 Naval Research Laboratory (NRL). The NRL Copyright Notice and License 9 Agreement Version 1.1 (January 17, 1995) applies to these portions of the 10 software. 11 You should have received a copy of the license with this software. If you 12 didn't get a copy, you may request one from <license@ipv6.nrl.navy.mil>. 13 14 */ 15 16 /* 17 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. 18 * All rights reserved. 19 * 20 * Redistribution and use in source and binary forms, with or without 21 * modification, are permitted provided that the following conditions 22 * are met: 23 * 1. Redistributions of source code must retain the above copyright 24 * notice, this list of conditions and the following disclaimer. 25 * 2. Redistributions in binary form must reproduce the above copyright 26 * notice, this list of conditions and the following disclaimer in the 27 * documentation and/or other materials provided with the distribution. 28 * 3. Neither the name of the project nor the names of its contributors 29 * may be used to endorse or promote products derived from this software 30 * without specific prior written permission. 31 * 32 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND 33 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 34 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 35 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE 36 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 37 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 38 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 39 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 40 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 41 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 42 * SUCH DAMAGE. 43 */ 44 45 /*- 46 * Copyright (c) 1997, 1998 The NetBSD Foundation, Inc. 47 * All rights reserved. 48 * 49 * This code is derived from software contributed to The NetBSD Foundation 50 * by Jason R. Thorpe and Kevin M. Lahey of the Numerical Aerospace Simulation 51 * Facility, NASA Ames Research Center. 52 * 53 * Redistribution and use in source and binary forms, with or without 54 * modification, are permitted provided that the following conditions 55 * are met: 56 * 1. Redistributions of source code must retain the above copyright 57 * notice, this list of conditions and the following disclaimer. 58 * 2. Redistributions in binary form must reproduce the above copyright 59 * notice, this list of conditions and the following disclaimer in the 60 * documentation and/or other materials provided with the distribution. 61 * 3. All advertising materials mentioning features or use of this software 62 * must display the following acknowledgement: 63 * This product includes software developed by the NetBSD 64 * Foundation, Inc. and its contributors. 65 * 4. Neither the name of The NetBSD Foundation nor the names of its 66 * contributors may be used to endorse or promote products derived 67 * from this software without specific prior written permission. 68 * 69 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 70 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 71 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 72 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 73 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 74 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 75 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 76 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 77 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 78 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 79 * POSSIBILITY OF SUCH DAMAGE. 80 */ 81 82 /* 83 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995 84 * The Regents of the University of California. All rights reserved. 85 * 86 * Redistribution and use in source and binary forms, with or without 87 * modification, are permitted provided that the following conditions 88 * are met: 89 * 1. Redistributions of source code must retain the above copyright 90 * notice, this list of conditions and the following disclaimer. 91 * 2. Redistributions in binary form must reproduce the above copyright 92 * notice, this list of conditions and the following disclaimer in the 93 * documentation and/or other materials provided with the distribution. 94 * 3. All advertising materials mentioning features or use of this software 95 * must display the following acknowledgement: 96 * This product includes software developed by the University of 97 * California, Berkeley and its contributors. 98 * 4. Neither the name of the University nor the names of its contributors 99 * may be used to endorse or promote products derived from this software 100 * without specific prior written permission. 101 * 102 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 103 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 104 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 105 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 106 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 107 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 108 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 109 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 110 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 111 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 112 * SUCH DAMAGE. 113 * 114 * @(#)tcp_output.c 8.4 (Berkeley) 5/24/95 115 */ 116 117 #include "opt_inet.h" 118 #include "opt_ipsec.h" 119 120 #include <sys/param.h> 121 #include <sys/systm.h> 122 #include <sys/malloc.h> 123 #include <sys/mbuf.h> 124 #include <sys/protosw.h> 125 #include <sys/socket.h> 126 #include <sys/socketvar.h> 127 #include <sys/errno.h> 128 #include <sys/domain.h> 129 130 #include <net/if.h> 131 #include <net/route.h> 132 133 #include <netinet/in.h> 134 #include <netinet/in_systm.h> 135 #include <netinet/ip.h> 136 #include <netinet/in_pcb.h> 137 #include <netinet/ip_var.h> 138 139 #ifdef INET6 140 #ifndef INET 141 #include <netinet/in.h> 142 #endif 143 #include <netinet/ip6.h> 144 #include <netinet6/in6_pcb.h> 145 #include <netinet6/ip6_var.h> 146 #endif 147 148 #include <netinet/tcp.h> 149 #define TCPOUTFLAGS 150 #include <netinet/tcp_fsm.h> 151 #include <netinet/tcp_seq.h> 152 #include <netinet/tcp_timer.h> 153 #include <netinet/tcp_var.h> 154 #include <netinet/tcpip.h> 155 #include <netinet/tcp_debug.h> 156 157 #ifdef notyet 158 extern struct mbuf *m_copypack(); 159 #endif 160 161 #define MAX_TCPOPTLEN 32 /* max # bytes that go in options */ 162 163 /* 164 * Knob to enable Congestion Window Monitoring, and control the 165 * the burst size it allows. Default burst is 4 packets, per 166 * the Internet draft. 167 */ 168 int tcp_cwm = 0; 169 int tcp_cwm_burstsize = 4; 170 171 static __inline void tcp_segsize __P((struct tcpcb *, int *, int *)); 172 static __inline void 173 tcp_segsize(tp, txsegsizep, rxsegsizep) 174 struct tcpcb *tp; 175 int *txsegsizep, *rxsegsizep; 176 { 177 #ifdef INET 178 struct inpcb *inp = tp->t_inpcb; 179 #endif 180 #ifdef INET6 181 struct in6pcb *in6p = tp->t_in6pcb; 182 #endif 183 struct rtentry *rt; 184 struct ifnet *ifp; 185 int size; 186 int iphlen; 187 188 #ifdef DIAGNOSTIC 189 if (tp->t_inpcb && tp->t_in6pcb) 190 panic("tcp_segsize: both t_inpcb and t_in6pcb are set"); 191 #endif 192 switch (tp->t_family) { 193 #ifdef INET 194 case AF_INET: 195 iphlen = sizeof(struct ip); 196 break; 197 #endif 198 #ifdef INET6 199 case AF_INET6: 200 iphlen = sizeof(struct ip6_hdr); 201 break; 202 #endif 203 default: 204 size = tcp_mssdflt; 205 goto out; 206 } 207 208 rt = NULL; 209 #ifdef INET 210 if (inp) 211 rt = in_pcbrtentry(inp); 212 #endif 213 #ifdef INET6 214 if (in6p) 215 rt = in6_pcbrtentry(in6p); 216 #endif 217 if (rt == NULL) { 218 size = tcp_mssdflt; 219 goto out; 220 } 221 222 ifp = rt->rt_ifp; 223 224 size = tcp_mssdflt; 225 if (rt->rt_rmx.rmx_mtu != 0) 226 size = rt->rt_rmx.rmx_mtu - iphlen - sizeof(struct tcphdr); 227 else if (ifp->if_flags & IFF_LOOPBACK) 228 size = ifp->if_mtu - iphlen - sizeof(struct tcphdr); 229 #ifdef INET 230 else if (ip_mtudisc) 231 size = ifp->if_mtu - iphlen - sizeof(struct tcphdr); 232 else if (inp && in_localaddr(inp->inp_faddr)) 233 size = ifp->if_mtu - iphlen - sizeof(struct tcphdr); 234 #endif 235 #ifdef INET6 236 else if (in6p) { 237 #ifdef INET 238 if (IN6_IS_ADDR_V4MAPPED(&in6p->in6p_faddr)) { 239 /* mapped addr case */ 240 struct in_addr d; 241 bcopy(&in6p->in6p_faddr.s6_addr32[3], &d, sizeof(d)); 242 if (in_localaddr(d)) 243 size = ifp->if_mtu - iphlen - sizeof(struct tcphdr); 244 } else 245 #endif 246 { 247 if (in6_localaddr(&in6p->in6p_faddr)) 248 size = ifp->if_mtu - iphlen - sizeof(struct tcphdr); 249 } 250 } 251 #endif 252 size -= tcp_optlen(tp); 253 /* 254 * XXX tp->t_ourmss should have the right size, but without this code 255 * fragmentation will occur... need more investigation 256 */ 257 #ifdef INET 258 if (inp) { 259 #ifdef IPSEC 260 size -= ipsec4_hdrsiz_tcp(tp); 261 #endif 262 size -= ip_optlen(inp); 263 } 264 #endif 265 #ifdef INET6 266 #ifdef INET 267 if (in6p && tp->t_family == AF_INET) { 268 #ifdef IPSEC 269 size -= ipsec4_hdrsiz_tcp(tp); 270 #endif 271 /* XXX size -= ip_optlen(in6p); */ 272 } else 273 #endif 274 if (in6p && tp->t_family == AF_INET6) { 275 #ifdef IPSEC 276 size -= ipsec6_hdrsiz_tcp(tp); 277 #endif 278 size -= ip6_optlen(in6p); 279 } 280 #endif 281 282 out: 283 /* 284 * *rxsegsizep holds *estimated* inbound segment size (estimation 285 * assumes that path MTU is the same for both ways). this is only 286 * for silly window avoidance, do not use the value for other purposes. 287 * 288 * ipseclen is subtracted from both sides, this may not be right. 289 * I'm not quite sure about this (could someone comment). 290 */ 291 *txsegsizep = min(tp->t_peermss, size); 292 *rxsegsizep = min(tp->t_ourmss, size); 293 294 if (*txsegsizep != tp->t_segsz) { 295 /* 296 * If the new segment size is larger, we don't want to 297 * mess up the congestion window, but if it is smaller 298 * we'll have to reduce the congestion window to ensure 299 * that we don't get into trouble with initial windows 300 * and the rest. In any case, if the segment size 301 * has changed, chances are the path has, too, and 302 * our congestion window will be different. 303 */ 304 if (*txsegsizep < tp->t_segsz) { 305 tp->snd_cwnd = max((tp->snd_cwnd / tp->t_segsz) 306 * *txsegsizep, *txsegsizep); 307 tp->snd_ssthresh = max((tp->snd_ssthresh / tp->t_segsz) 308 * *txsegsizep, *txsegsizep); 309 } 310 tp->t_segsz = *txsegsizep; 311 } 312 } 313 314 /* 315 * Tcp output routine: figure out what should be sent and send it. 316 */ 317 int 318 tcp_output(tp) 319 struct tcpcb *tp; 320 { 321 struct socket *so; 322 struct route *ro; 323 long len, win; 324 int off, flags, error; 325 struct mbuf *m; 326 struct ip *ip; 327 #ifdef INET6 328 struct ip6_hdr *ip6; 329 #endif 330 struct tcphdr *th; 331 u_char opt[MAX_TCPOPTLEN]; 332 unsigned optlen, hdrlen; 333 int idle, sendalot, txsegsize, rxsegsize; 334 int maxburst = TCP_MAXBURST; 335 int af; /* address family on the wire */ 336 int iphdrlen; 337 338 #ifdef DIAGNOSTIC 339 if (tp->t_inpcb && tp->t_in6pcb) 340 panic("tcp_output: both t_inpcb and t_in6pcb are set"); 341 #endif 342 so = NULL; 343 ro = NULL; 344 if (tp->t_inpcb) { 345 so = tp->t_inpcb->inp_socket; 346 ro = &tp->t_inpcb->inp_route; 347 } 348 #ifdef INET6 349 else if (tp->t_in6pcb) { 350 so = tp->t_in6pcb->in6p_socket; 351 ro = (struct route *)&tp->t_in6pcb->in6p_route; 352 } 353 #endif 354 355 switch (af = tp->t_family) { 356 #ifdef INET 357 case AF_INET: 358 if (tp->t_inpcb) 359 break; 360 #ifdef INET6 361 /* mapped addr case */ 362 if (tp->t_in6pcb) 363 break; 364 #endif 365 return EINVAL; 366 #endif 367 #ifdef INET6 368 case AF_INET6: 369 if (tp->t_in6pcb) 370 break; 371 return EINVAL; 372 #endif 373 default: 374 return EAFNOSUPPORT; 375 } 376 377 tcp_segsize(tp, &txsegsize, &rxsegsize); 378 379 idle = (tp->snd_max == tp->snd_una); 380 381 /* 382 * Restart Window computation. From draft-floyd-incr-init-win-03: 383 * 384 * Optionally, a TCP MAY set the restart window to the 385 * minimum of the value used for the initial window and 386 * the current value of cwnd (in other words, using a 387 * larger value for the restart window should never increase 388 * the size of cwnd). 389 */ 390 if (tcp_cwm) { 391 /* 392 * Hughes/Touch/Heidemann Congestion Window Monitoring. 393 * Count the number of packets currently pending 394 * acknowledgement, and limit our congestion window 395 * to a pre-determined allowed burst size plus that count. 396 * This prevents bursting once all pending packets have 397 * been acknowledged (i.e. transmission is idle). 398 * 399 * XXX Link this to Initial Window? 400 */ 401 tp->snd_cwnd = min(tp->snd_cwnd, 402 (tcp_cwm_burstsize * txsegsize) + 403 (tp->snd_nxt - tp->snd_una)); 404 } else { 405 if (idle && tp->t_idle >= tp->t_rxtcur) { 406 /* 407 * We have been idle for "a while" and no acks are 408 * expected to clock out any data we send -- 409 * slow start to get ack "clock" running again. 410 */ 411 tp->snd_cwnd = min(tp->snd_cwnd, 412 TCP_INITIAL_WINDOW(tcp_init_win, txsegsize)); 413 } 414 } 415 416 again: 417 /* 418 * Determine length of data that should be transmitted, and 419 * flags that should be used. If there is some data or critical 420 * controls (SYN, RST) to send, then transmit; otherwise, 421 * investigate further. 422 */ 423 sendalot = 0; 424 off = tp->snd_nxt - tp->snd_una; 425 win = min(tp->snd_wnd, tp->snd_cwnd); 426 427 flags = tcp_outflags[tp->t_state]; 428 /* 429 * If in persist timeout with window of 0, send 1 byte. 430 * Otherwise, if window is small but nonzero 431 * and timer expired, we will send what we can 432 * and go to transmit state. 433 */ 434 if (tp->t_force) { 435 if (win == 0) { 436 /* 437 * If we still have some data to send, then 438 * clear the FIN bit. Usually this would 439 * happen below when it realizes that we 440 * aren't sending all the data. However, 441 * if we have exactly 1 byte of unset data, 442 * then it won't clear the FIN bit below, 443 * and if we are in persist state, we wind 444 * up sending the packet without recording 445 * that we sent the FIN bit. 446 * 447 * We can't just blindly clear the FIN bit, 448 * because if we don't have any more data 449 * to send then the probe will be the FIN 450 * itself. 451 */ 452 if (off < so->so_snd.sb_cc) 453 flags &= ~TH_FIN; 454 win = 1; 455 } else { 456 TCP_TIMER_DISARM(tp, TCPT_PERSIST); 457 tp->t_rxtshift = 0; 458 } 459 } 460 461 if (win < so->so_snd.sb_cc) { 462 len = win - off; 463 flags &= ~TH_FIN; 464 } else 465 len = so->so_snd.sb_cc - off; 466 467 if (len < 0) { 468 /* 469 * If FIN has been sent but not acked, 470 * but we haven't been called to retransmit, 471 * len will be -1. Otherwise, window shrank 472 * after we sent into it. If window shrank to 0, 473 * cancel pending retransmit, pull snd_nxt back 474 * to (closed) window, and set the persist timer 475 * if it isn't already going. If the window didn't 476 * close completely, just wait for an ACK. 477 * 478 * If we have a pending FIN, either it has already been 479 * transmitted or it is outside the window, so drop it. 480 * If the FIN has been transmitted, but this is not a 481 * retransmission, then len must be -1. Therefore we also 482 * prevent here the sending of `gratuitous FINs'. This 483 * eliminates the need to check for that case below (e.g. 484 * to back up snd_nxt before the FIN so that the sequence 485 * number is correct). 486 */ 487 len = 0; 488 flags &= ~TH_FIN; 489 if (win == 0) { 490 TCP_TIMER_DISARM(tp, TCPT_REXMT); 491 tp->t_rxtshift = 0; 492 tp->snd_nxt = tp->snd_una; 493 if (TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) 494 tcp_setpersist(tp); 495 } 496 } 497 if (len > txsegsize) { 498 len = txsegsize; 499 flags &= ~TH_FIN; 500 sendalot = 1; 501 } 502 503 win = sbspace(&so->so_rcv); 504 505 /* 506 * Sender silly window avoidance. If connection is idle 507 * and can send all data, a maximum segment, 508 * at least a maximum default-size segment do it, 509 * or are forced, do it; otherwise don't bother. 510 * If peer's buffer is tiny, then send 511 * when window is at least half open. 512 * If retransmitting (possibly after persist timer forced us 513 * to send into a small window), then must resend. 514 */ 515 if (len) { 516 if (len == txsegsize) 517 goto send; 518 if ((so->so_state & SS_MORETOCOME) == 0 && 519 ((idle || tp->t_flags & TF_NODELAY) && 520 len + off >= so->so_snd.sb_cc)) 521 goto send; 522 if (tp->t_force) 523 goto send; 524 if (len >= tp->max_sndwnd / 2) 525 goto send; 526 if (SEQ_LT(tp->snd_nxt, tp->snd_max)) 527 goto send; 528 } 529 530 /* 531 * Compare available window to amount of window known to peer 532 * (as advertised window less next expected input). If the 533 * difference is at least twice the size of the largest segment 534 * we expect to receive (i.e. two segments) or at least 50% of 535 * the maximum possible window, then want to send a window update 536 * to peer. 537 */ 538 if (win > 0) { 539 /* 540 * "adv" is the amount we can increase the window, 541 * taking into account that we are limited by 542 * TCP_MAXWIN << tp->rcv_scale. 543 */ 544 long adv = min(win, (long)TCP_MAXWIN << tp->rcv_scale) - 545 (tp->rcv_adv - tp->rcv_nxt); 546 547 if (adv >= (long) (2 * rxsegsize)) 548 goto send; 549 if (2 * adv >= (long) so->so_rcv.sb_hiwat) 550 goto send; 551 } 552 553 /* 554 * Send if we owe peer an ACK. 555 */ 556 if (tp->t_flags & TF_ACKNOW) 557 goto send; 558 if (flags & (TH_SYN|TH_FIN|TH_RST)) 559 goto send; 560 if (SEQ_GT(tp->snd_up, tp->snd_una)) 561 goto send; 562 563 /* 564 * TCP window updates are not reliable, rather a polling protocol 565 * using ``persist'' packets is used to insure receipt of window 566 * updates. The three ``states'' for the output side are: 567 * idle not doing retransmits or persists 568 * persisting to move a small or zero window 569 * (re)transmitting and thereby not persisting 570 * 571 * tp->t_timer[TCPT_PERSIST] 572 * is set when we are in persist state. 573 * tp->t_force 574 * is set when we are called to send a persist packet. 575 * tp->t_timer[TCPT_REXMT] 576 * is set when we are retransmitting 577 * The output side is idle when both timers are zero. 578 * 579 * If send window is too small, there is data to transmit, and no 580 * retransmit or persist is pending, then go to persist state. 581 * If nothing happens soon, send when timer expires: 582 * if window is nonzero, transmit what we can, 583 * otherwise force out a byte. 584 */ 585 if (so->so_snd.sb_cc && TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 && 586 TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) { 587 tp->t_rxtshift = 0; 588 tcp_setpersist(tp); 589 } 590 591 /* 592 * No reason to send a segment, just return. 593 */ 594 return (0); 595 596 send: 597 /* 598 * Before ESTABLISHED, force sending of initial options 599 * unless TCP set not to do any options. 600 * NOTE: we assume that the IP/TCP header plus TCP options 601 * always fit in a single mbuf, leaving room for a maximum 602 * link header, i.e. 603 * max_linkhdr + sizeof (struct tcpiphdr) + optlen <= MCLBYTES 604 */ 605 optlen = 0; 606 switch (af) { 607 #ifdef INET 608 case AF_INET: 609 iphdrlen = sizeof(struct ip) + sizeof(struct tcphdr); 610 break; 611 #endif 612 #ifdef INET6 613 case AF_INET6: 614 iphdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 615 break; 616 #endif 617 default: /*pacify gcc*/ 618 iphdrlen = 0; 619 break; 620 } 621 hdrlen = iphdrlen; 622 if (flags & TH_SYN) { 623 struct rtentry *rt; 624 625 rt = NULL; 626 #ifdef INET 627 if (tp->t_inpcb) 628 rt = in_pcbrtentry(tp->t_inpcb); 629 #endif 630 #ifdef INET6 631 if (tp->t_in6pcb) 632 rt = in6_pcbrtentry(tp->t_in6pcb); 633 #endif 634 635 tp->snd_nxt = tp->iss; 636 tp->t_ourmss = tcp_mss_to_advertise(rt != NULL ? 637 rt->rt_ifp : NULL, af); 638 if ((tp->t_flags & TF_NOOPT) == 0) { 639 opt[0] = TCPOPT_MAXSEG; 640 opt[1] = 4; 641 opt[2] = (tp->t_ourmss >> 8) & 0xff; 642 opt[3] = tp->t_ourmss & 0xff; 643 optlen = 4; 644 645 if ((tp->t_flags & TF_REQ_SCALE) && 646 ((flags & TH_ACK) == 0 || 647 (tp->t_flags & TF_RCVD_SCALE))) { 648 *((u_int32_t *) (opt + optlen)) = htonl( 649 TCPOPT_NOP << 24 | 650 TCPOPT_WINDOW << 16 | 651 TCPOLEN_WINDOW << 8 | 652 tp->request_r_scale); 653 optlen += 4; 654 } 655 } 656 } 657 658 /* 659 * Send a timestamp and echo-reply if this is a SYN and our side 660 * wants to use timestamps (TF_REQ_TSTMP is set) or both our side 661 * and our peer have sent timestamps in our SYN's. 662 */ 663 if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP && 664 (flags & TH_RST) == 0 && 665 ((flags & (TH_SYN|TH_ACK)) == TH_SYN || 666 (tp->t_flags & TF_RCVD_TSTMP))) { 667 u_int32_t *lp = (u_int32_t *)(opt + optlen); 668 669 /* Form timestamp option as shown in appendix A of RFC 1323. */ 670 *lp++ = htonl(TCPOPT_TSTAMP_HDR); 671 *lp++ = htonl(tcp_now); 672 *lp = htonl(tp->ts_recent); 673 optlen += TCPOLEN_TSTAMP_APPA; 674 } 675 676 hdrlen += optlen; 677 678 #ifdef DIAGNOSTIC 679 if (len > txsegsize) 680 panic("tcp data to be sent is larger than segment"); 681 if (max_linkhdr + hdrlen > MCLBYTES) 682 panic("tcphdr too big"); 683 #endif 684 685 /* 686 * Grab a header mbuf, attaching a copy of data to 687 * be transmitted, and initialize the header from 688 * the template for sends on this connection. 689 */ 690 if (len) { 691 if (tp->t_force && len == 1) 692 tcpstat.tcps_sndprobe++; 693 else if (SEQ_LT(tp->snd_nxt, tp->snd_max)) { 694 tcpstat.tcps_sndrexmitpack++; 695 tcpstat.tcps_sndrexmitbyte += len; 696 } else { 697 tcpstat.tcps_sndpack++; 698 tcpstat.tcps_sndbyte += len; 699 } 700 #ifdef notyet 701 if ((m = m_copypack(so->so_snd.sb_mb, off, 702 (int)len, max_linkhdr + hdrlen)) == 0) { 703 error = ENOBUFS; 704 goto out; 705 } 706 /* 707 * m_copypack left space for our hdr; use it. 708 */ 709 m->m_len += hdrlen; 710 m->m_data -= hdrlen; 711 #else 712 MGETHDR(m, M_DONTWAIT, MT_HEADER); 713 if (m != NULL && 714 (max_linkhdr + hdrlen > MHLEN || 715 max_linkhdr + hdrlen + len <= MCLBYTES)) { 716 MCLGET(m, M_DONTWAIT); 717 if ((m->m_flags & M_EXT) == 0) { 718 m_freem(m); 719 m = NULL; 720 } 721 } 722 if (m == NULL) { 723 error = ENOBUFS; 724 goto out; 725 } 726 m->m_data += max_linkhdr; 727 m->m_len = hdrlen; 728 if (len <= M_TRAILINGSPACE(m)) { 729 m_copydata(so->so_snd.sb_mb, off, (int) len, 730 mtod(m, caddr_t) + hdrlen); 731 m->m_len += len; 732 } else { 733 m->m_next = m_copy(so->so_snd.sb_mb, off, (int) len); 734 if (m->m_next == NULL) { 735 m_freem(m); 736 error = ENOBUFS; 737 goto out; 738 } 739 } 740 #endif 741 /* 742 * If we're sending everything we've got, set PUSH. 743 * (This will keep happy those implementations which only 744 * give data to the user when a buffer fills or 745 * a PUSH comes in.) 746 */ 747 if (off + len == so->so_snd.sb_cc) 748 flags |= TH_PUSH; 749 } else { 750 if (tp->t_flags & TF_ACKNOW) 751 tcpstat.tcps_sndacks++; 752 else if (flags & (TH_SYN|TH_FIN|TH_RST)) 753 tcpstat.tcps_sndctrl++; 754 else if (SEQ_GT(tp->snd_up, tp->snd_una)) 755 tcpstat.tcps_sndurg++; 756 else 757 tcpstat.tcps_sndwinup++; 758 759 MGETHDR(m, M_DONTWAIT, MT_HEADER); 760 if (m != NULL && max_linkhdr + hdrlen > MHLEN) { 761 MCLGET(m, M_DONTWAIT); 762 if ((m->m_flags & M_EXT) == 0) { 763 m_freem(m); 764 m = NULL; 765 } 766 } 767 if (m == NULL) { 768 error = ENOBUFS; 769 goto out; 770 } 771 m->m_data += max_linkhdr; 772 m->m_len = hdrlen; 773 } 774 m->m_pkthdr.rcvif = (struct ifnet *)0; 775 switch (af) { 776 #ifdef INET 777 case AF_INET: 778 ip = mtod(m, struct ip *); 779 #ifdef INET6 780 ip6 = NULL; 781 #endif 782 th = (struct tcphdr *)(ip + 1); 783 break; 784 #endif 785 #ifdef INET6 786 case AF_INET6: 787 ip = NULL; 788 ip6 = mtod(m, struct ip6_hdr *); 789 th = (struct tcphdr *)(ip6 + 1); 790 break; 791 #endif 792 default: /*pacify gcc*/ 793 ip = NULL; 794 #ifdef INET6 795 ip6 = NULL; 796 #endif 797 th = NULL; 798 break; 799 } 800 if (tp->t_template == 0) 801 panic("tcp_output"); 802 if (tp->t_template->m_len < iphdrlen) 803 panic("tcp_output"); 804 bcopy(mtod(tp->t_template, caddr_t), mtod(m, caddr_t), iphdrlen); 805 806 /* 807 * If we are doing retransmissions, then snd_nxt will 808 * not reflect the first unsent octet. For ACK only 809 * packets, we do not want the sequence number of the 810 * retransmitted packet, we want the sequence number 811 * of the next unsent octet. So, if there is no data 812 * (and no SYN or FIN), use snd_max instead of snd_nxt 813 * when filling in ti_seq. But if we are in persist 814 * state, snd_max might reflect one byte beyond the 815 * right edge of the window, so use snd_nxt in that 816 * case, since we know we aren't doing a retransmission. 817 * (retransmit and persist are mutually exclusive...) 818 */ 819 if (len || (flags & (TH_SYN|TH_FIN)) || 820 TCP_TIMER_ISARMED(tp, TCPT_PERSIST)) 821 th->th_seq = htonl(tp->snd_nxt); 822 else 823 th->th_seq = htonl(tp->snd_max); 824 th->th_ack = htonl(tp->rcv_nxt); 825 if (optlen) { 826 bcopy((caddr_t)opt, (caddr_t)(th + 1), optlen); 827 th->th_off = (sizeof (struct tcphdr) + optlen) >> 2; 828 } 829 th->th_flags = flags; 830 /* 831 * Calculate receive window. Don't shrink window, 832 * but avoid silly window syndrome. 833 */ 834 if (win < (long)(so->so_rcv.sb_hiwat / 4) && win < (long)rxsegsize) 835 win = 0; 836 if (win > (long)TCP_MAXWIN << tp->rcv_scale) 837 win = (long)TCP_MAXWIN << tp->rcv_scale; 838 if (win < (long)(tp->rcv_adv - tp->rcv_nxt)) 839 win = (long)(tp->rcv_adv - tp->rcv_nxt); 840 th->th_win = htons((u_int16_t) (win>>tp->rcv_scale)); 841 if (SEQ_GT(tp->snd_up, tp->snd_nxt)) { 842 u_int32_t urp = tp->snd_up - tp->snd_nxt; 843 if (urp > IP_MAXPACKET) 844 urp = IP_MAXPACKET; 845 th->th_urp = htons((u_int16_t)urp); 846 th->th_flags |= TH_URG; 847 } else 848 /* 849 * If no urgent pointer to send, then we pull 850 * the urgent pointer to the left edge of the send window 851 * so that it doesn't drift into the send window on sequence 852 * number wraparound. 853 */ 854 tp->snd_up = tp->snd_una; /* drag it along */ 855 856 /* 857 * Put TCP length in extended header, and then 858 * checksum extended header and data. 859 */ 860 switch (af) { 861 #ifdef INET 862 case AF_INET: 863 { 864 struct ipovly *ipov = (struct ipovly *)ip; 865 if (len + optlen) 866 ipov->ih_len = htons((u_int16_t)(sizeof(struct tcphdr) + 867 optlen + len)); 868 bzero(ipov->ih_x1, sizeof(ipov->ih_x1)); 869 th->th_sum = 0; 870 th->th_sum = in_cksum(m, (int)(hdrlen + len)); 871 break; 872 } 873 #endif 874 #ifdef INET6 875 case AF_INET6: 876 /* equals to hdrlen + len */ 877 m->m_pkthdr.len = sizeof(struct ip6_hdr) 878 + sizeof(struct tcphdr) + optlen + len; 879 th->th_sum = 0; 880 th->th_sum = in6_cksum(m, IPPROTO_TCP, 881 sizeof(struct ip6_hdr), 882 sizeof(struct tcphdr) + optlen + len); 883 break; 884 #endif 885 } 886 887 /* 888 * In transmit state, time the transmission and arrange for 889 * the retransmit. In persist state, just set snd_max. 890 */ 891 if (tp->t_force == 0 || TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) { 892 tcp_seq startseq = tp->snd_nxt; 893 894 /* 895 * Advance snd_nxt over sequence space of this segment. 896 * There are no states in which we send both a SYN and a FIN, 897 * so we collapse the tests for these flags. 898 */ 899 if (flags & (TH_SYN|TH_FIN)) 900 tp->snd_nxt++; 901 tp->snd_nxt += len; 902 if (SEQ_GT(tp->snd_nxt, tp->snd_max)) { 903 tp->snd_max = tp->snd_nxt; 904 /* 905 * Time this transmission if not a retransmission and 906 * not currently timing anything. 907 */ 908 if (tp->t_rtt == 0) { 909 tp->t_rtt = 1; 910 tp->t_rtseq = startseq; 911 tcpstat.tcps_segstimed++; 912 } 913 } 914 915 /* 916 * Set retransmit timer if not currently set, 917 * and not doing an ack or a keep-alive probe. 918 * Initial value for retransmit timer is smoothed 919 * round-trip time + 2 * round-trip time variance. 920 * Initialize shift counter which is used for backoff 921 * of retransmit time. 922 */ 923 if (TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 && 924 tp->snd_nxt != tp->snd_una) { 925 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 926 if (TCP_TIMER_ISARMED(tp, TCPT_PERSIST)) { 927 TCP_TIMER_DISARM(tp, TCPT_PERSIST); 928 tp->t_rxtshift = 0; 929 } 930 } 931 } else 932 if (SEQ_GT(tp->snd_nxt + len, tp->snd_max)) 933 tp->snd_max = tp->snd_nxt + len; 934 935 /* 936 * Trace. 937 */ 938 if (so->so_options & SO_DEBUG) { 939 /* 940 * need to recover version # field, which was overwritten 941 * on ip_cksum computation. 942 */ 943 struct ip *sip; 944 sip = mtod(m, struct ip *); 945 switch (af) { 946 #ifdef INET 947 case AF_INET: 948 sip->ip_v = 4; 949 break; 950 #endif 951 #ifdef INET6 952 case AF_INET6: 953 sip->ip_v = 6; 954 break; 955 #endif 956 } 957 tcp_trace(TA_OUTPUT, tp->t_state, tp, m, 0); 958 } 959 960 /* 961 * Fill in IP length and desired time to live and 962 * send to IP level. There should be a better way 963 * to handle ttl and tos; we could keep them in 964 * the template, but need a way to checksum without them. 965 */ 966 m->m_pkthdr.len = hdrlen + len; 967 968 switch (af) { 969 #ifdef INET 970 case AF_INET: 971 ip->ip_len = m->m_pkthdr.len; 972 if (tp->t_inpcb) { 973 ip->ip_ttl = tp->t_inpcb->inp_ip.ip_ttl; 974 ip->ip_tos = tp->t_inpcb->inp_ip.ip_tos; 975 } 976 #ifdef INET6 977 else if (tp->t_in6pcb) { 978 ip->ip_ttl = in6_selecthlim(tp->t_in6pcb, NULL); /*XXX*/ 979 ip->ip_tos = 0; /*XXX*/ 980 } 981 #endif 982 break; 983 #endif 984 #ifdef INET6 985 case AF_INET6: 986 ip6->ip6_nxt = IPPROTO_TCP; 987 if (tp->t_in6pcb) { 988 /* 989 * we separately set hoplimit for every segment, since 990 * the user might want to change the value via 991 * setsockopt. Also, desired default hop limit might 992 * be changed via Neighbor Discovery. 993 */ 994 ip6->ip6_hlim = in6_selecthlim(tp->t_in6pcb, 995 ro->ro_rt ? ro->ro_rt->rt_ifp : NULL); 996 } 997 /* ip6->ip6_flow = ??? */ 998 /* ip6_plen will be filled in ip6_output(). */ 999 break; 1000 #endif 1001 } 1002 1003 #ifdef IPSEC 1004 ipsec_setsocket(m, so); 1005 #endif /*IPSEC*/ 1006 1007 switch (af) { 1008 #ifdef INET 1009 case AF_INET: 1010 { 1011 struct mbuf *opts; 1012 1013 if (tp->t_inpcb) 1014 opts = tp->t_inpcb->inp_options; 1015 else 1016 opts = NULL; 1017 error = ip_output(m, opts, ro, 1018 (ip_mtudisc ? IP_MTUDISC : 0) | 1019 (so->so_options & SO_DONTROUTE), 1020 0); 1021 break; 1022 } 1023 #endif 1024 #ifdef INET6 1025 case AF_INET6: 1026 { 1027 struct ip6_pktopts *opts; 1028 1029 if (tp->t_in6pcb) 1030 opts = tp->t_in6pcb->in6p_outputopts; 1031 else 1032 opts = NULL; 1033 error = ip6_output(m, opts, (struct route_in6 *)ro, 1034 so->so_options & SO_DONTROUTE, 0, NULL); 1035 break; 1036 } 1037 #endif 1038 default: 1039 error = EAFNOSUPPORT; 1040 break; 1041 } 1042 if (error) { 1043 out: 1044 if (error == ENOBUFS) { 1045 #ifdef INET 1046 if (tp->t_inpcb) 1047 tcp_quench(tp->t_inpcb, 0); 1048 #endif 1049 #ifdef INET6 1050 if (tp->t_in6pcb) 1051 tcp6_quench(tp->t_in6pcb, 0); 1052 #endif 1053 return (0); 1054 } 1055 if ((error == EHOSTUNREACH || error == ENETDOWN) 1056 && TCPS_HAVERCVDSYN(tp->t_state)) { 1057 tp->t_softerror = error; 1058 return (0); 1059 } 1060 return (error); 1061 } 1062 tcpstat.tcps_sndtotal++; 1063 if (tp->t_flags & TF_DELACK) 1064 tcpstat.tcps_delack++; 1065 1066 /* 1067 * Data sent (as far as we can tell). 1068 * If this advertises a larger window than any other segment, 1069 * then remember the size of the advertised window. 1070 * Any pending ACK has now been sent. 1071 */ 1072 if (win > 0 && SEQ_GT(tp->rcv_nxt+win, tp->rcv_adv)) 1073 tp->rcv_adv = tp->rcv_nxt + win; 1074 tp->last_ack_sent = tp->rcv_nxt; 1075 tp->t_flags &= ~TF_ACKNOW; 1076 TCP_CLEAR_DELACK(tp); 1077 #ifdef DIAGNOSTIC 1078 if (maxburst < 0) 1079 printf("tcp_output: maxburst exceeded by %d\n", -maxburst); 1080 #endif 1081 if (sendalot && (!tcp_do_newreno || --maxburst)) 1082 goto again; 1083 return (0); 1084 } 1085 1086 void 1087 tcp_setpersist(tp) 1088 struct tcpcb *tp; 1089 { 1090 int t = ((tp->t_srtt >> 2) + tp->t_rttvar) >> (1 + 2); 1091 int nticks; 1092 1093 if (TCP_TIMER_ISARMED(tp, TCPT_REXMT)) 1094 panic("tcp_output REXMT"); 1095 /* 1096 * Start/restart persistance timer. 1097 */ 1098 if (t < tp->t_rttmin) 1099 t = tp->t_rttmin; 1100 TCPT_RANGESET(nticks, t * tcp_backoff[tp->t_rxtshift], 1101 TCPTV_PERSMIN, TCPTV_PERSMAX); 1102 TCP_TIMER_ARM(tp, TCPT_PERSIST, nticks); 1103 if (tp->t_rxtshift < TCP_MAXRXTSHIFT) 1104 tp->t_rxtshift++; 1105 } 1106