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1 /* $NetBSD: tcp_output.c,v 1.108.2.1 2004/05/11 13:00:20 tron Exp $ */ 2 3 /* 4 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. 5 * 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. Neither the name of the project nor the names of its contributors 16 * may be used to endorse or promote products derived from this software 17 * without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 32 /* 33 * @(#)COPYRIGHT 1.1 (NRL) 17 January 1995 34 * 35 * NRL grants permission for redistribution and use in source and binary 36 * forms, with or without modification, of the software and documentation 37 * created at NRL provided that the following conditions are met: 38 * 39 * 1. Redistributions of source code must retain the above copyright 40 * notice, this list of conditions and the following disclaimer. 41 * 2. Redistributions in binary form must reproduce the above copyright 42 * notice, this list of conditions and the following disclaimer in the 43 * documentation and/or other materials provided with the distribution. 44 * 3. All advertising materials mentioning features or use of this software 45 * must display the following acknowledgements: 46 * This product includes software developed by the University of 47 * California, Berkeley and its contributors. 48 * This product includes software developed at the Information 49 * Technology Division, US Naval Research Laboratory. 50 * 4. Neither the name of the NRL nor the names of its contributors 51 * may be used to endorse or promote products derived from this software 52 * without specific prior written permission. 53 * 54 * THE SOFTWARE PROVIDED BY NRL IS PROVIDED BY NRL AND CONTRIBUTORS ``AS 55 * IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 56 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A 57 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL NRL OR 58 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 59 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 60 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 61 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF 62 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 63 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 64 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 65 * 66 * The views and conclusions contained in the software and documentation 67 * are those of the authors and should not be interpreted as representing 68 * official policies, either expressed or implied, of the US Naval 69 * Research Laboratory (NRL). 70 */ 71 72 /*- 73 * Copyright (c) 1997, 1998, 2001 The NetBSD Foundation, Inc. 74 * All rights reserved. 75 * 76 * This code is derived from software contributed to The NetBSD Foundation 77 * by Jason R. Thorpe and Kevin M. Lahey of the Numerical Aerospace Simulation 78 * Facility, NASA Ames Research Center. 79 * 80 * Redistribution and use in source and binary forms, with or without 81 * modification, are permitted provided that the following conditions 82 * are met: 83 * 1. Redistributions of source code must retain the above copyright 84 * notice, this list of conditions and the following disclaimer. 85 * 2. Redistributions in binary form must reproduce the above copyright 86 * notice, this list of conditions and the following disclaimer in the 87 * documentation and/or other materials provided with the distribution. 88 * 3. All advertising materials mentioning features or use of this software 89 * must display the following acknowledgement: 90 * This product includes software developed by the NetBSD 91 * Foundation, Inc. and its contributors. 92 * 4. Neither the name of The NetBSD Foundation nor the names of its 93 * contributors may be used to endorse or promote products derived 94 * from this software without specific prior written permission. 95 * 96 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 97 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 98 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 99 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 100 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 101 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 102 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 103 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 104 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 105 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 106 * POSSIBILITY OF SUCH DAMAGE. 107 */ 108 109 /* 110 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995 111 * The Regents of the University of California. All rights reserved. 112 * 113 * Redistribution and use in source and binary forms, with or without 114 * modification, are permitted provided that the following conditions 115 * are met: 116 * 1. Redistributions of source code must retain the above copyright 117 * notice, this list of conditions and the following disclaimer. 118 * 2. Redistributions in binary form must reproduce the above copyright 119 * notice, this list of conditions and the following disclaimer in the 120 * documentation and/or other materials provided with the distribution. 121 * 3. Neither the name of the University nor the names of its contributors 122 * may be used to endorse or promote products derived from this software 123 * without specific prior written permission. 124 * 125 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 126 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 127 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 128 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 129 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 130 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 131 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 132 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 133 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 134 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 135 * SUCH DAMAGE. 136 * 137 * @(#)tcp_output.c 8.4 (Berkeley) 5/24/95 138 */ 139 140 #include <sys/cdefs.h> 141 __KERNEL_RCSID(0, "$NetBSD: tcp_output.c,v 1.108.2.1 2004/05/11 13:00:20 tron Exp $"); 142 143 #include "opt_inet.h" 144 #include "opt_ipsec.h" 145 #include "opt_tcp_debug.h" 146 147 #include <sys/param.h> 148 #include <sys/systm.h> 149 #include <sys/malloc.h> 150 #include <sys/mbuf.h> 151 #include <sys/protosw.h> 152 #include <sys/socket.h> 153 #include <sys/socketvar.h> 154 #include <sys/errno.h> 155 #include <sys/domain.h> 156 #include <sys/kernel.h> 157 158 #include <net/if.h> 159 #include <net/route.h> 160 161 #include <netinet/in.h> 162 #include <netinet/in_systm.h> 163 #include <netinet/ip.h> 164 #include <netinet/in_pcb.h> 165 #include <netinet/ip_var.h> 166 167 #ifdef INET6 168 #ifndef INET 169 #include <netinet/in.h> 170 #endif 171 #include <netinet/ip6.h> 172 #include <netinet6/in6_var.h> 173 #include <netinet6/ip6_var.h> 174 #include <netinet6/in6_pcb.h> 175 #include <netinet6/nd6.h> 176 #endif 177 178 #ifdef FAST_IPSEC 179 #include <netipsec/ipsec.h> 180 #endif /* FAST_IPSEC*/ 181 #ifdef IPSEC 182 #include <netinet6/ipsec.h> 183 #endif 184 185 #include <netinet/tcp.h> 186 #define TCPOUTFLAGS 187 #include <netinet/tcp_fsm.h> 188 #include <netinet/tcp_seq.h> 189 #include <netinet/tcp_timer.h> 190 #include <netinet/tcp_var.h> 191 #include <netinet/tcpip.h> 192 #include <netinet/tcp_debug.h> 193 194 #ifdef notyet 195 extern struct mbuf *m_copypack(); 196 #endif 197 198 #define MAX_TCPOPTLEN 32 /* max # bytes that go in options */ 199 200 /* 201 * Knob to enable Congestion Window Monitoring, and control the 202 * the burst size it allows. Default burst is 4 packets, per 203 * the Internet draft. 204 */ 205 int tcp_cwm = 0; 206 int tcp_cwm_burstsize = 4; 207 208 #ifdef TCP_OUTPUT_COUNTERS 209 #include <sys/device.h> 210 211 extern struct evcnt tcp_output_bigheader; 212 extern struct evcnt tcp_output_predict_hit; 213 extern struct evcnt tcp_output_predict_miss; 214 extern struct evcnt tcp_output_copysmall; 215 extern struct evcnt tcp_output_copybig; 216 extern struct evcnt tcp_output_refbig; 217 218 #define TCP_OUTPUT_COUNTER_INCR(ev) (ev)->ev_count++ 219 #else 220 221 #define TCP_OUTPUT_COUNTER_INCR(ev) /* nothing */ 222 223 #endif /* TCP_OUTPUT_COUNTERS */ 224 225 static 226 #ifndef GPROF 227 __inline 228 #endif 229 int 230 tcp_segsize(struct tcpcb *tp, int *txsegsizep, int *rxsegsizep) 231 { 232 #ifdef INET 233 struct inpcb *inp = tp->t_inpcb; 234 #endif 235 #ifdef INET6 236 struct in6pcb *in6p = tp->t_in6pcb; 237 #endif 238 struct socket *so = NULL; 239 struct rtentry *rt; 240 struct ifnet *ifp; 241 int size; 242 int iphlen; 243 int optlen; 244 245 #ifdef DIAGNOSTIC 246 if (tp->t_inpcb && tp->t_in6pcb) 247 panic("tcp_segsize: both t_inpcb and t_in6pcb are set"); 248 #endif 249 switch (tp->t_family) { 250 #ifdef INET 251 case AF_INET: 252 iphlen = sizeof(struct ip); 253 break; 254 #endif 255 #ifdef INET6 256 case AF_INET6: 257 iphlen = sizeof(struct ip6_hdr); 258 break; 259 #endif 260 default: 261 size = tcp_mssdflt; 262 goto out; 263 } 264 265 rt = NULL; 266 #ifdef INET 267 if (inp) { 268 rt = in_pcbrtentry(inp); 269 so = inp->inp_socket; 270 } 271 #endif 272 #ifdef INET6 273 if (in6p) { 274 rt = in6_pcbrtentry(in6p); 275 so = in6p->in6p_socket; 276 } 277 #endif 278 if (rt == NULL) { 279 size = tcp_mssdflt; 280 goto out; 281 } 282 283 ifp = rt->rt_ifp; 284 285 size = tcp_mssdflt; 286 if (tp->t_mtudisc && rt->rt_rmx.rmx_mtu != 0) { 287 #ifdef INET6 288 if (in6p && rt->rt_rmx.rmx_mtu < IPV6_MMTU) { 289 /* 290 * RFC2460 section 5, last paragraph: if path MTU is 291 * smaller than 1280, use 1280 as packet size and 292 * attach fragment header. 293 */ 294 size = IPV6_MMTU - iphlen - sizeof(struct ip6_frag) - 295 sizeof(struct tcphdr); 296 } else 297 size = rt->rt_rmx.rmx_mtu - iphlen - 298 sizeof(struct tcphdr); 299 #else 300 size = rt->rt_rmx.rmx_mtu - iphlen - sizeof(struct tcphdr); 301 #endif 302 } else if (ifp->if_flags & IFF_LOOPBACK) 303 size = ifp->if_mtu - iphlen - sizeof(struct tcphdr); 304 #ifdef INET 305 else if (inp && tp->t_mtudisc) 306 size = ifp->if_mtu - iphlen - sizeof(struct tcphdr); 307 else if (inp && in_localaddr(inp->inp_faddr)) 308 size = ifp->if_mtu - iphlen - sizeof(struct tcphdr); 309 #endif 310 #ifdef INET6 311 else if (in6p) { 312 #ifdef INET 313 if (IN6_IS_ADDR_V4MAPPED(&in6p->in6p_faddr)) { 314 /* mapped addr case */ 315 struct in_addr d; 316 bcopy(&in6p->in6p_faddr.s6_addr32[3], &d, sizeof(d)); 317 if (tp->t_mtudisc || in_localaddr(d)) 318 size = ifp->if_mtu - iphlen - sizeof(struct tcphdr); 319 } else 320 #endif 321 { 322 /* 323 * for IPv6, path MTU discovery is always turned on, 324 * or the node must use packet size <= 1280. 325 */ 326 size = tp->t_mtudisc ? IN6_LINKMTU(ifp) : IPV6_MMTU; 327 size -= (iphlen + sizeof(struct tcphdr)); 328 } 329 } 330 #endif 331 out: 332 /* 333 * Now we must make room for whatever extra TCP/IP options are in 334 * the packet. 335 */ 336 optlen = tcp_optlen(tp); 337 338 /* 339 * XXX tp->t_ourmss should have the right size, but without this code 340 * fragmentation will occur... need more investigation 341 */ 342 #ifdef INET 343 if (inp) { 344 #if defined(IPSEC) || defined(FAST_IPSEC) 345 if (! IPSEC_PCB_SKIP_IPSEC(inp->inp_sp, IPSEC_DIR_OUTBOUND)) 346 optlen += ipsec4_hdrsiz_tcp(tp); 347 #endif 348 optlen += ip_optlen(inp); 349 } 350 #endif 351 #ifdef INET6 352 #ifdef INET 353 if (in6p && tp->t_family == AF_INET) { 354 #if defined(IPSEC) || defined(FAST_IPSEC) 355 if (! IPSEC_PCB_SKIP_IPSEC(in6p->in6p_sp, IPSEC_DIR_OUTBOUND)) 356 optlen += ipsec4_hdrsiz_tcp(tp); 357 #endif 358 /* XXX size -= ip_optlen(in6p); */ 359 } else 360 #endif 361 if (in6p && tp->t_family == AF_INET6) { 362 #ifdef IPSEC 363 if (! IPSEC_PCB_SKIP_IPSEC(in6p->in6p_sp, IPSEC_DIR_OUTBOUND)) 364 optlen += ipsec6_hdrsiz_tcp(tp); 365 #endif 366 optlen += ip6_optlen(in6p); 367 } 368 #endif 369 size -= optlen; 370 371 /* there may not be any room for data if mtu is too small */ 372 if (size < 0) 373 return (EMSGSIZE); 374 375 /* 376 * *rxsegsizep holds *estimated* inbound segment size (estimation 377 * assumes that path MTU is the same for both ways). this is only 378 * for silly window avoidance, do not use the value for other purposes. 379 * 380 * ipseclen is subtracted from both sides, this may not be right. 381 * I'm not quite sure about this (could someone comment). 382 */ 383 *txsegsizep = min(tp->t_peermss - optlen, size); 384 /* 385 * Never send more than half a buffer full. This insures that we can 386 * always keep 2 packets on the wire, no matter what SO_SNDBUF is, and 387 * therefore acks will never be delayed unless we run out of data to 388 * transmit. 389 */ 390 if (so) 391 *txsegsizep = min(so->so_snd.sb_hiwat >> 1, *txsegsizep); 392 *rxsegsizep = min(tp->t_ourmss - optlen, size); 393 394 if (*txsegsizep != tp->t_segsz) { 395 /* 396 * If the new segment size is larger, we don't want to 397 * mess up the congestion window, but if it is smaller 398 * we'll have to reduce the congestion window to ensure 399 * that we don't get into trouble with initial windows 400 * and the rest. In any case, if the segment size 401 * has changed, chances are the path has, too, and 402 * our congestion window will be different. 403 */ 404 if (*txsegsizep < tp->t_segsz) { 405 tp->snd_cwnd = max((tp->snd_cwnd / tp->t_segsz) 406 * *txsegsizep, *txsegsizep); 407 tp->snd_ssthresh = max((tp->snd_ssthresh / tp->t_segsz) 408 * *txsegsizep, *txsegsizep); 409 } 410 tp->t_segsz = *txsegsizep; 411 } 412 413 return (0); 414 } 415 416 static 417 #ifndef GPROF 418 __inline 419 #endif 420 int 421 tcp_build_datapkt(struct tcpcb *tp, struct socket *so, int off, 422 long len, int hdrlen, struct mbuf **mp) 423 { 424 struct mbuf *m, *m0; 425 426 if (tp->t_force && len == 1) 427 tcpstat.tcps_sndprobe++; 428 else if (SEQ_LT(tp->snd_nxt, tp->snd_max)) { 429 tcpstat.tcps_sndrexmitpack++; 430 tcpstat.tcps_sndrexmitbyte += len; 431 } else { 432 tcpstat.tcps_sndpack++; 433 tcpstat.tcps_sndbyte += len; 434 } 435 #ifdef notyet 436 if ((m = m_copypack(so->so_snd.sb_mb, off, 437 (int)len, max_linkhdr + hdrlen)) == 0) 438 return (ENOBUFS); 439 /* 440 * m_copypack left space for our hdr; use it. 441 */ 442 m->m_len += hdrlen; 443 m->m_data -= hdrlen; 444 #else 445 MGETHDR(m, M_DONTWAIT, MT_HEADER); 446 if (__predict_false(m == NULL)) 447 return (ENOBUFS); 448 MCLAIM(m, &tcp_tx_mowner); 449 450 /* 451 * XXX Because other code assumes headers will fit in 452 * XXX one header mbuf. 453 * 454 * (This code should almost *never* be run.) 455 */ 456 if (__predict_false((max_linkhdr + hdrlen) > MHLEN)) { 457 TCP_OUTPUT_COUNTER_INCR(&tcp_output_bigheader); 458 MCLGET(m, M_DONTWAIT); 459 if ((m->m_flags & M_EXT) == 0) { 460 m_freem(m); 461 return (ENOBUFS); 462 } 463 } 464 465 m->m_data += max_linkhdr; 466 m->m_len = hdrlen; 467 468 /* 469 * To avoid traversing the whole sb_mb chain for correct 470 * data to send, remember last sent mbuf, its offset and 471 * the sent size. When called the next time, see if the 472 * data to send is directly following the previous transfer. 473 * This is important for large TCP windows. 474 */ 475 if (off == 0 || tp->t_lastm == NULL || 476 (tp->t_lastoff + tp->t_lastlen) != off) { 477 TCP_OUTPUT_COUNTER_INCR(&tcp_output_predict_miss); 478 /* 479 * Either a new packet or a retransmit. 480 * Start from the beginning. 481 */ 482 tp->t_lastm = so->so_snd.sb_mb; 483 tp->t_inoff = off; 484 } else { 485 TCP_OUTPUT_COUNTER_INCR(&tcp_output_predict_hit); 486 tp->t_inoff += tp->t_lastlen; 487 } 488 489 /* Traverse forward to next packet */ 490 while (tp->t_inoff > 0) { 491 if (tp->t_lastm == NULL) 492 panic("tp->t_lastm == NULL"); 493 if (tp->t_inoff < tp->t_lastm->m_len) 494 break; 495 tp->t_inoff -= tp->t_lastm->m_len; 496 tp->t_lastm = tp->t_lastm->m_next; 497 } 498 499 tp->t_lastoff = off; 500 tp->t_lastlen = len; 501 m0 = tp->t_lastm; 502 off = tp->t_inoff; 503 504 if (len <= M_TRAILINGSPACE(m)) { 505 m_copydata(m0, off, (int) len, mtod(m, caddr_t) + hdrlen); 506 m->m_len += len; 507 TCP_OUTPUT_COUNTER_INCR(&tcp_output_copysmall); 508 } else { 509 m->m_next = m_copy(m0, off, (int) len); 510 if (m->m_next == NULL) { 511 m_freem(m); 512 return (ENOBUFS); 513 } 514 #ifdef TCP_OUTPUT_COUNTERS 515 if (m->m_next->m_flags & M_EXT) 516 TCP_OUTPUT_COUNTER_INCR(&tcp_output_refbig); 517 else 518 TCP_OUTPUT_COUNTER_INCR(&tcp_output_copybig); 519 #endif /* TCP_OUTPUT_COUNTERS */ 520 } 521 #endif 522 523 *mp = m; 524 return (0); 525 } 526 527 /* 528 * Tcp output routine: figure out what should be sent and send it. 529 */ 530 int 531 tcp_output(tp) 532 struct tcpcb *tp; 533 { 534 struct socket *so; 535 struct route *ro; 536 long len, win; 537 int off, flags, error; 538 struct mbuf *m; 539 struct ip *ip; 540 #ifdef INET6 541 struct ip6_hdr *ip6; 542 #endif 543 struct tcphdr *th; 544 u_char opt[MAX_TCPOPTLEN]; 545 unsigned optlen, hdrlen; 546 int idle, sendalot, txsegsize, rxsegsize; 547 int maxburst = TCP_MAXBURST; 548 int af; /* address family on the wire */ 549 int iphdrlen; 550 551 #ifdef DIAGNOSTIC 552 if (tp->t_inpcb && tp->t_in6pcb) 553 panic("tcp_output: both t_inpcb and t_in6pcb are set"); 554 #endif 555 so = NULL; 556 ro = NULL; 557 if (tp->t_inpcb) { 558 so = tp->t_inpcb->inp_socket; 559 ro = &tp->t_inpcb->inp_route; 560 } 561 #ifdef INET6 562 else if (tp->t_in6pcb) { 563 so = tp->t_in6pcb->in6p_socket; 564 ro = (struct route *)&tp->t_in6pcb->in6p_route; 565 } 566 #endif 567 568 switch (af = tp->t_family) { 569 #ifdef INET 570 case AF_INET: 571 if (tp->t_inpcb) 572 break; 573 #ifdef INET6 574 /* mapped addr case */ 575 if (tp->t_in6pcb) 576 break; 577 #endif 578 return (EINVAL); 579 #endif 580 #ifdef INET6 581 case AF_INET6: 582 if (tp->t_in6pcb) 583 break; 584 return (EINVAL); 585 #endif 586 default: 587 return (EAFNOSUPPORT); 588 } 589 590 if (tcp_segsize(tp, &txsegsize, &rxsegsize)) 591 return (EMSGSIZE); 592 593 idle = (tp->snd_max == tp->snd_una); 594 595 /* 596 * Restart Window computation. From draft-floyd-incr-init-win-03: 597 * 598 * Optionally, a TCP MAY set the restart window to the 599 * minimum of the value used for the initial window and 600 * the current value of cwnd (in other words, using a 601 * larger value for the restart window should never increase 602 * the size of cwnd). 603 */ 604 if (tcp_cwm) { 605 /* 606 * Hughes/Touch/Heidemann Congestion Window Monitoring. 607 * Count the number of packets currently pending 608 * acknowledgement, and limit our congestion window 609 * to a pre-determined allowed burst size plus that count. 610 * This prevents bursting once all pending packets have 611 * been acknowledged (i.e. transmission is idle). 612 * 613 * XXX Link this to Initial Window? 614 */ 615 tp->snd_cwnd = min(tp->snd_cwnd, 616 (tcp_cwm_burstsize * txsegsize) + 617 (tp->snd_nxt - tp->snd_una)); 618 } else { 619 if (idle && (tcp_now - tp->t_rcvtime) >= tp->t_rxtcur) { 620 /* 621 * We have been idle for "a while" and no acks are 622 * expected to clock out any data we send -- 623 * slow start to get ack "clock" running again. 624 */ 625 int ss = tcp_init_win; 626 #ifdef INET 627 if (tp->t_inpcb && 628 in_localaddr(tp->t_inpcb->inp_faddr)) 629 ss = tcp_init_win_local; 630 #endif 631 #ifdef INET6 632 if (tp->t_in6pcb && 633 in6_localaddr(&tp->t_in6pcb->in6p_faddr)) 634 ss = tcp_init_win_local; 635 #endif 636 tp->snd_cwnd = min(tp->snd_cwnd, 637 TCP_INITIAL_WINDOW(ss, txsegsize)); 638 } 639 } 640 641 again: 642 /* 643 * Determine length of data that should be transmitted, and 644 * flags that should be used. If there is some data or critical 645 * controls (SYN, RST) to send, then transmit; otherwise, 646 * investigate further. 647 */ 648 sendalot = 0; 649 off = tp->snd_nxt - tp->snd_una; 650 win = min(tp->snd_wnd, tp->snd_cwnd); 651 652 flags = tcp_outflags[tp->t_state]; 653 /* 654 * If in persist timeout with window of 0, send 1 byte. 655 * Otherwise, if window is small but nonzero 656 * and timer expired, we will send what we can 657 * and go to transmit state. 658 */ 659 if (tp->t_force) { 660 if (win == 0) { 661 /* 662 * If we still have some data to send, then 663 * clear the FIN bit. Usually this would 664 * happen below when it realizes that we 665 * aren't sending all the data. However, 666 * if we have exactly 1 byte of unset data, 667 * then it won't clear the FIN bit below, 668 * and if we are in persist state, we wind 669 * up sending the packet without recording 670 * that we sent the FIN bit. 671 * 672 * We can't just blindly clear the FIN bit, 673 * because if we don't have any more data 674 * to send then the probe will be the FIN 675 * itself. 676 */ 677 if (off < so->so_snd.sb_cc) 678 flags &= ~TH_FIN; 679 win = 1; 680 } else { 681 TCP_TIMER_DISARM(tp, TCPT_PERSIST); 682 tp->t_rxtshift = 0; 683 } 684 } 685 686 if (win < so->so_snd.sb_cc) { 687 len = win - off; 688 flags &= ~TH_FIN; 689 } else 690 len = so->so_snd.sb_cc - off; 691 692 if (len < 0) { 693 /* 694 * If FIN has been sent but not acked, 695 * but we haven't been called to retransmit, 696 * len will be -1. Otherwise, window shrank 697 * after we sent into it. If window shrank to 0, 698 * cancel pending retransmit, pull snd_nxt back 699 * to (closed) window, and set the persist timer 700 * if it isn't already going. If the window didn't 701 * close completely, just wait for an ACK. 702 * 703 * If we have a pending FIN, either it has already been 704 * transmitted or it is outside the window, so drop it. 705 * If the FIN has been transmitted, but this is not a 706 * retransmission, then len must be -1. Therefore we also 707 * prevent here the sending of `gratuitous FINs'. This 708 * eliminates the need to check for that case below (e.g. 709 * to back up snd_nxt before the FIN so that the sequence 710 * number is correct). 711 */ 712 len = 0; 713 flags &= ~TH_FIN; 714 if (win == 0) { 715 TCP_TIMER_DISARM(tp, TCPT_REXMT); 716 tp->t_rxtshift = 0; 717 tp->snd_nxt = tp->snd_una; 718 if (TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) 719 tcp_setpersist(tp); 720 } 721 } 722 if (len > txsegsize) { 723 len = txsegsize; 724 flags &= ~TH_FIN; 725 sendalot = 1; 726 } 727 728 win = sbspace(&so->so_rcv); 729 730 /* 731 * Sender silly window avoidance. If connection is idle 732 * and can send all data, a maximum segment, 733 * at least a maximum default-size segment do it, 734 * or are forced, do it; otherwise don't bother. 735 * If peer's buffer is tiny, then send 736 * when window is at least half open. 737 * If retransmitting (possibly after persist timer forced us 738 * to send into a small window), then must resend. 739 */ 740 if (len) { 741 if (len == txsegsize) 742 goto send; 743 if ((so->so_state & SS_MORETOCOME) == 0 && 744 ((idle || tp->t_flags & TF_NODELAY) && 745 len + off >= so->so_snd.sb_cc)) 746 goto send; 747 if (tp->t_force) 748 goto send; 749 if (len >= tp->max_sndwnd / 2) 750 goto send; 751 if (SEQ_LT(tp->snd_nxt, tp->snd_max)) 752 goto send; 753 } 754 755 /* 756 * Compare available window to amount of window known to peer 757 * (as advertised window less next expected input). If the 758 * difference is at least twice the size of the largest segment 759 * we expect to receive (i.e. two segments) or at least 50% of 760 * the maximum possible window, then want to send a window update 761 * to peer. 762 */ 763 if (win > 0) { 764 /* 765 * "adv" is the amount we can increase the window, 766 * taking into account that we are limited by 767 * TCP_MAXWIN << tp->rcv_scale. 768 */ 769 long adv = min(win, (long)TCP_MAXWIN << tp->rcv_scale) - 770 (tp->rcv_adv - tp->rcv_nxt); 771 772 if (adv >= (long) (2 * rxsegsize)) 773 goto send; 774 if (2 * adv >= (long) so->so_rcv.sb_hiwat) 775 goto send; 776 } 777 778 /* 779 * Send if we owe peer an ACK. 780 */ 781 if (tp->t_flags & TF_ACKNOW) 782 goto send; 783 if (flags & (TH_SYN|TH_FIN|TH_RST)) 784 goto send; 785 if (SEQ_GT(tp->snd_up, tp->snd_una)) 786 goto send; 787 788 /* 789 * TCP window updates are not reliable, rather a polling protocol 790 * using ``persist'' packets is used to insure receipt of window 791 * updates. The three ``states'' for the output side are: 792 * idle not doing retransmits or persists 793 * persisting to move a small or zero window 794 * (re)transmitting and thereby not persisting 795 * 796 * tp->t_timer[TCPT_PERSIST] 797 * is set when we are in persist state. 798 * tp->t_force 799 * is set when we are called to send a persist packet. 800 * tp->t_timer[TCPT_REXMT] 801 * is set when we are retransmitting 802 * The output side is idle when both timers are zero. 803 * 804 * If send window is too small, there is data to transmit, and no 805 * retransmit or persist is pending, then go to persist state. 806 * If nothing happens soon, send when timer expires: 807 * if window is nonzero, transmit what we can, 808 * otherwise force out a byte. 809 */ 810 if (so->so_snd.sb_cc && TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 && 811 TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) { 812 tp->t_rxtshift = 0; 813 tcp_setpersist(tp); 814 } 815 816 /* 817 * No reason to send a segment, just return. 818 */ 819 return (0); 820 821 send: 822 /* 823 * Before ESTABLISHED, force sending of initial options 824 * unless TCP set not to do any options. 825 * NOTE: we assume that the IP/TCP header plus TCP options 826 * always fit in a single mbuf, leaving room for a maximum 827 * link header, i.e. 828 * max_linkhdr + sizeof (struct tcpiphdr) + optlen <= MCLBYTES 829 */ 830 optlen = 0; 831 switch (af) { 832 #ifdef INET 833 case AF_INET: 834 iphdrlen = sizeof(struct ip) + sizeof(struct tcphdr); 835 break; 836 #endif 837 #ifdef INET6 838 case AF_INET6: 839 iphdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 840 break; 841 #endif 842 default: /*pacify gcc*/ 843 iphdrlen = 0; 844 break; 845 } 846 hdrlen = iphdrlen; 847 if (flags & TH_SYN) { 848 struct rtentry *rt; 849 850 rt = NULL; 851 #ifdef INET 852 if (tp->t_inpcb) 853 rt = in_pcbrtentry(tp->t_inpcb); 854 #endif 855 #ifdef INET6 856 if (tp->t_in6pcb) 857 rt = in6_pcbrtentry(tp->t_in6pcb); 858 #endif 859 860 tp->snd_nxt = tp->iss; 861 tp->t_ourmss = tcp_mss_to_advertise(rt != NULL ? 862 rt->rt_ifp : NULL, af); 863 if ((tp->t_flags & TF_NOOPT) == 0) { 864 opt[0] = TCPOPT_MAXSEG; 865 opt[1] = 4; 866 opt[2] = (tp->t_ourmss >> 8) & 0xff; 867 opt[3] = tp->t_ourmss & 0xff; 868 optlen = 4; 869 870 if ((tp->t_flags & TF_REQ_SCALE) && 871 ((flags & TH_ACK) == 0 || 872 (tp->t_flags & TF_RCVD_SCALE))) { 873 *((u_int32_t *) (opt + optlen)) = htonl( 874 TCPOPT_NOP << 24 | 875 TCPOPT_WINDOW << 16 | 876 TCPOLEN_WINDOW << 8 | 877 tp->request_r_scale); 878 optlen += 4; 879 } 880 } 881 } 882 883 /* 884 * Send a timestamp and echo-reply if this is a SYN and our side 885 * wants to use timestamps (TF_REQ_TSTMP is set) or both our side 886 * and our peer have sent timestamps in our SYN's. 887 */ 888 if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP && 889 (flags & TH_RST) == 0 && 890 ((flags & (TH_SYN|TH_ACK)) == TH_SYN || 891 (tp->t_flags & TF_RCVD_TSTMP))) { 892 u_int32_t *lp = (u_int32_t *)(opt + optlen); 893 894 /* Form timestamp option as shown in appendix A of RFC 1323. */ 895 *lp++ = htonl(TCPOPT_TSTAMP_HDR); 896 *lp++ = htonl(TCP_TIMESTAMP(tp)); 897 *lp = htonl(tp->ts_recent); 898 optlen += TCPOLEN_TSTAMP_APPA; 899 } 900 901 hdrlen += optlen; 902 903 #ifdef DIAGNOSTIC 904 if (len > txsegsize) 905 panic("tcp data to be sent is larger than segment"); 906 if (max_linkhdr + hdrlen > MCLBYTES) 907 panic("tcphdr too big"); 908 #endif 909 910 /* 911 * Grab a header mbuf, attaching a copy of data to 912 * be transmitted, and initialize the header from 913 * the template for sends on this connection. 914 */ 915 if (len) { 916 error = tcp_build_datapkt(tp, so, off, len, hdrlen, &m); 917 if (error) 918 goto out; 919 /* 920 * If we're sending everything we've got, set PUSH. 921 * (This will keep happy those implementations which only 922 * give data to the user when a buffer fills or 923 * a PUSH comes in.) 924 */ 925 if (off + len == so->so_snd.sb_cc) 926 flags |= TH_PUSH; 927 } else { 928 if (tp->t_flags & TF_ACKNOW) 929 tcpstat.tcps_sndacks++; 930 else if (flags & (TH_SYN|TH_FIN|TH_RST)) 931 tcpstat.tcps_sndctrl++; 932 else if (SEQ_GT(tp->snd_up, tp->snd_una)) 933 tcpstat.tcps_sndurg++; 934 else 935 tcpstat.tcps_sndwinup++; 936 937 MGETHDR(m, M_DONTWAIT, MT_HEADER); 938 if (m != NULL && max_linkhdr + hdrlen > MHLEN) { 939 MCLGET(m, M_DONTWAIT); 940 if ((m->m_flags & M_EXT) == 0) { 941 m_freem(m); 942 m = NULL; 943 } 944 } 945 if (m == NULL) { 946 error = ENOBUFS; 947 goto out; 948 } 949 MCLAIM(m, &tcp_tx_mowner); 950 m->m_data += max_linkhdr; 951 m->m_len = hdrlen; 952 } 953 m->m_pkthdr.rcvif = (struct ifnet *)0; 954 switch (af) { 955 #ifdef INET 956 case AF_INET: 957 ip = mtod(m, struct ip *); 958 #ifdef INET6 959 ip6 = NULL; 960 #endif 961 th = (struct tcphdr *)(ip + 1); 962 break; 963 #endif 964 #ifdef INET6 965 case AF_INET6: 966 ip = NULL; 967 ip6 = mtod(m, struct ip6_hdr *); 968 th = (struct tcphdr *)(ip6 + 1); 969 break; 970 #endif 971 default: /*pacify gcc*/ 972 ip = NULL; 973 #ifdef INET6 974 ip6 = NULL; 975 #endif 976 th = NULL; 977 break; 978 } 979 if (tp->t_template == 0) 980 panic("tcp_output"); 981 if (tp->t_template->m_len < iphdrlen) 982 panic("tcp_output"); 983 bcopy(mtod(tp->t_template, caddr_t), mtod(m, caddr_t), iphdrlen); 984 985 /* 986 * If we are doing retransmissions, then snd_nxt will 987 * not reflect the first unsent octet. For ACK only 988 * packets, we do not want the sequence number of the 989 * retransmitted packet, we want the sequence number 990 * of the next unsent octet. So, if there is no data 991 * (and no SYN or FIN), use snd_max instead of snd_nxt 992 * when filling in ti_seq. But if we are in persist 993 * state, snd_max might reflect one byte beyond the 994 * right edge of the window, so use snd_nxt in that 995 * case, since we know we aren't doing a retransmission. 996 * (retransmit and persist are mutually exclusive...) 997 */ 998 if (len || (flags & (TH_SYN|TH_FIN)) || 999 TCP_TIMER_ISARMED(tp, TCPT_PERSIST)) 1000 th->th_seq = htonl(tp->snd_nxt); 1001 else 1002 th->th_seq = htonl(tp->snd_max); 1003 th->th_ack = htonl(tp->rcv_nxt); 1004 if (optlen) { 1005 bcopy((caddr_t)opt, (caddr_t)(th + 1), optlen); 1006 th->th_off = (sizeof (struct tcphdr) + optlen) >> 2; 1007 } 1008 th->th_flags = flags; 1009 /* 1010 * Calculate receive window. Don't shrink window, 1011 * but avoid silly window syndrome. 1012 */ 1013 if (win < (long)(so->so_rcv.sb_hiwat / 4) && win < (long)rxsegsize) 1014 win = 0; 1015 if (win > (long)TCP_MAXWIN << tp->rcv_scale) 1016 win = (long)TCP_MAXWIN << tp->rcv_scale; 1017 if (win < (long)(int32_t)(tp->rcv_adv - tp->rcv_nxt)) 1018 win = (long)(int32_t)(tp->rcv_adv - tp->rcv_nxt); 1019 th->th_win = htons((u_int16_t) (win>>tp->rcv_scale)); 1020 if (SEQ_GT(tp->snd_up, tp->snd_nxt)) { 1021 u_int32_t urp = tp->snd_up - tp->snd_nxt; 1022 if (urp > IP_MAXPACKET) 1023 urp = IP_MAXPACKET; 1024 th->th_urp = htons((u_int16_t)urp); 1025 th->th_flags |= TH_URG; 1026 } else 1027 /* 1028 * If no urgent pointer to send, then we pull 1029 * the urgent pointer to the left edge of the send window 1030 * so that it doesn't drift into the send window on sequence 1031 * number wraparound. 1032 */ 1033 tp->snd_up = tp->snd_una; /* drag it along */ 1034 1035 /* 1036 * Set ourselves up to be checksummed just before the packet 1037 * hits the wire. 1038 */ 1039 switch (af) { 1040 #ifdef INET 1041 case AF_INET: 1042 m->m_pkthdr.csum_flags = M_CSUM_TCPv4; 1043 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 1044 if (len + optlen) { 1045 /* Fixup the pseudo-header checksum. */ 1046 /* XXXJRT Not IP Jumbogram safe. */ 1047 th->th_sum = in_cksum_addword(th->th_sum, 1048 htons((u_int16_t) (len + optlen))); 1049 } 1050 break; 1051 #endif 1052 #ifdef INET6 1053 case AF_INET6: 1054 /* 1055 * XXX Actually delaying the checksum is Hard 1056 * XXX (well, maybe not for Itojun, but it is 1057 * XXX for me), but we can still take advantage 1058 * XXX of the cached pseudo-header checksum. 1059 */ 1060 /* equals to hdrlen + len */ 1061 m->m_pkthdr.len = sizeof(struct ip6_hdr) 1062 + sizeof(struct tcphdr) + optlen + len; 1063 #ifdef notyet 1064 m->m_pkthdr.csum_flags = M_CSUM_TCPv6; 1065 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 1066 #endif 1067 if (len + optlen) { 1068 /* Fixup the pseudo-header checksum. */ 1069 /* XXXJRT: Not IPv6 Jumbogram safe. */ 1070 th->th_sum = in_cksum_addword(th->th_sum, 1071 htons((u_int16_t) (len + optlen))); 1072 } 1073 #ifndef notyet 1074 th->th_sum = in6_cksum(m, 0, sizeof(struct ip6_hdr), 1075 sizeof(struct tcphdr) + optlen + len); 1076 #endif 1077 break; 1078 #endif 1079 } 1080 1081 /* 1082 * In transmit state, time the transmission and arrange for 1083 * the retransmit. In persist state, just set snd_max. 1084 */ 1085 if (tp->t_force == 0 || TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) { 1086 tcp_seq startseq = tp->snd_nxt; 1087 1088 /* 1089 * Advance snd_nxt over sequence space of this segment. 1090 * There are no states in which we send both a SYN and a FIN, 1091 * so we collapse the tests for these flags. 1092 */ 1093 if (flags & (TH_SYN|TH_FIN)) 1094 tp->snd_nxt++; 1095 tp->snd_nxt += len; 1096 if (SEQ_GT(tp->snd_nxt, tp->snd_max)) { 1097 tp->snd_max = tp->snd_nxt; 1098 /* 1099 * Time this transmission if not a retransmission and 1100 * not currently timing anything. 1101 */ 1102 if (tp->t_rtttime == 0) { 1103 tp->t_rtttime = tcp_now; 1104 tp->t_rtseq = startseq; 1105 tcpstat.tcps_segstimed++; 1106 } 1107 } 1108 1109 /* 1110 * Set retransmit timer if not currently set, 1111 * and not doing an ack or a keep-alive probe. 1112 * Initial value for retransmit timer is smoothed 1113 * round-trip time + 2 * round-trip time variance. 1114 * Initialize shift counter which is used for backoff 1115 * of retransmit time. 1116 */ 1117 if (TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 && 1118 tp->snd_nxt != tp->snd_una) { 1119 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 1120 if (TCP_TIMER_ISARMED(tp, TCPT_PERSIST)) { 1121 TCP_TIMER_DISARM(tp, TCPT_PERSIST); 1122 tp->t_rxtshift = 0; 1123 } 1124 } 1125 } else 1126 if (SEQ_GT(tp->snd_nxt + len, tp->snd_max)) 1127 tp->snd_max = tp->snd_nxt + len; 1128 1129 #ifdef TCP_DEBUG 1130 /* 1131 * Trace. 1132 */ 1133 if (so->so_options & SO_DEBUG) 1134 tcp_trace(TA_OUTPUT, tp->t_state, tp, m, 0); 1135 #endif 1136 1137 /* 1138 * Fill in IP length and desired time to live and 1139 * send to IP level. There should be a better way 1140 * to handle ttl and tos; we could keep them in 1141 * the template, but need a way to checksum without them. 1142 */ 1143 m->m_pkthdr.len = hdrlen + len; 1144 1145 switch (af) { 1146 #ifdef INET 1147 case AF_INET: 1148 ip->ip_len = htons(m->m_pkthdr.len); 1149 if (tp->t_inpcb) { 1150 ip->ip_ttl = tp->t_inpcb->inp_ip.ip_ttl; 1151 ip->ip_tos = tp->t_inpcb->inp_ip.ip_tos; 1152 } 1153 #ifdef INET6 1154 else if (tp->t_in6pcb) { 1155 ip->ip_ttl = in6_selecthlim(tp->t_in6pcb, NULL); /*XXX*/ 1156 ip->ip_tos = 0; /*XXX*/ 1157 } 1158 #endif 1159 break; 1160 #endif 1161 #ifdef INET6 1162 case AF_INET6: 1163 ip6->ip6_nxt = IPPROTO_TCP; 1164 if (tp->t_in6pcb) { 1165 /* 1166 * we separately set hoplimit for every segment, since 1167 * the user might want to change the value via 1168 * setsockopt. Also, desired default hop limit might 1169 * be changed via Neighbor Discovery. 1170 */ 1171 ip6->ip6_hlim = in6_selecthlim(tp->t_in6pcb, 1172 ro->ro_rt ? ro->ro_rt->rt_ifp : NULL); 1173 } 1174 /* ip6->ip6_flow = ??? */ 1175 /* ip6_plen will be filled in ip6_output(). */ 1176 break; 1177 #endif 1178 } 1179 1180 switch (af) { 1181 #ifdef INET 1182 case AF_INET: 1183 { 1184 struct mbuf *opts; 1185 1186 if (tp->t_inpcb) 1187 opts = tp->t_inpcb->inp_options; 1188 else 1189 opts = NULL; 1190 error = ip_output(m, opts, ro, 1191 (tp->t_mtudisc ? IP_MTUDISC : 0) | 1192 (so->so_options & SO_DONTROUTE), 1193 (struct ip_moptions *)0, so); 1194 break; 1195 } 1196 #endif 1197 #ifdef INET6 1198 case AF_INET6: 1199 { 1200 struct ip6_pktopts *opts; 1201 1202 if (tp->t_in6pcb) 1203 opts = tp->t_in6pcb->in6p_outputopts; 1204 else 1205 opts = NULL; 1206 error = ip6_output(m, opts, (struct route_in6 *)ro, 1207 so->so_options & SO_DONTROUTE, 1208 (struct ip6_moptions *)0, so, NULL); 1209 break; 1210 } 1211 #endif 1212 default: 1213 error = EAFNOSUPPORT; 1214 break; 1215 } 1216 if (error) { 1217 out: 1218 if (error == ENOBUFS) { 1219 tcpstat.tcps_selfquench++; 1220 #ifdef INET 1221 if (tp->t_inpcb) 1222 tcp_quench(tp->t_inpcb, 0); 1223 #endif 1224 #ifdef INET6 1225 if (tp->t_in6pcb) 1226 tcp6_quench(tp->t_in6pcb, 0); 1227 #endif 1228 error = 0; 1229 } else if ((error == EHOSTUNREACH || error == ENETDOWN) && 1230 TCPS_HAVERCVDSYN(tp->t_state)) { 1231 tp->t_softerror = error; 1232 error = 0; 1233 } 1234 1235 /* Restart the delayed ACK timer, if necessary. */ 1236 if (tp->t_flags & TF_DELACK) 1237 TCP_RESTART_DELACK(tp); 1238 1239 return (error); 1240 } 1241 tcpstat.tcps_sndtotal++; 1242 if (tp->t_flags & TF_DELACK) 1243 tcpstat.tcps_delack++; 1244 1245 /* 1246 * Data sent (as far as we can tell). 1247 * If this advertises a larger window than any other segment, 1248 * then remember the size of the advertised window. 1249 * Any pending ACK has now been sent. 1250 */ 1251 if (win > 0 && SEQ_GT(tp->rcv_nxt+win, tp->rcv_adv)) 1252 tp->rcv_adv = tp->rcv_nxt + win; 1253 tp->last_ack_sent = tp->rcv_nxt; 1254 tp->t_flags &= ~TF_ACKNOW; 1255 TCP_CLEAR_DELACK(tp); 1256 #ifdef DIAGNOSTIC 1257 if (maxburst < 0) 1258 printf("tcp_output: maxburst exceeded by %d\n", -maxburst); 1259 #endif 1260 if (sendalot && (!tcp_do_newreno || --maxburst)) 1261 goto again; 1262 return (0); 1263 } 1264 1265 void 1266 tcp_setpersist(tp) 1267 struct tcpcb *tp; 1268 { 1269 int t = ((tp->t_srtt >> 2) + tp->t_rttvar) >> (1 + 2); 1270 int nticks; 1271 1272 if (TCP_TIMER_ISARMED(tp, TCPT_REXMT)) 1273 panic("tcp_output REXMT"); 1274 /* 1275 * Start/restart persistance timer. 1276 */ 1277 if (t < tp->t_rttmin) 1278 t = tp->t_rttmin; 1279 TCPT_RANGESET(nticks, t * tcp_backoff[tp->t_rxtshift], 1280 TCPTV_PERSMIN, TCPTV_PERSMAX); 1281 TCP_TIMER_ARM(tp, TCPT_PERSIST, nticks); 1282 if (tp->t_rxtshift < TCP_MAXRXTSHIFT) 1283 tp->t_rxtshift++; 1284 }
Cache object: 9e427b7aa654cf0f4692dda59d4ff25c
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