tcp_output.c revision 1.162.12.2
1 /* $NetBSD: tcp_output.c,v 1.162.12.2 2008/01/19 12:15:33 bouyer 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, 2005, 2006 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 * This code is derived from software contributed to The NetBSD Foundation 80 * by Charles M. Hannum. 81 * This code is derived from software contributed to The NetBSD Foundation 82 * by Rui Paulo. 83 * 84 * Redistribution and use in source and binary forms, with or without 85 * modification, are permitted provided that the following conditions 86 * are met: 87 * 1. Redistributions of source code must retain the above copyright 88 * notice, this list of conditions and the following disclaimer. 89 * 2. Redistributions in binary form must reproduce the above copyright 90 * notice, this list of conditions and the following disclaimer in the 91 * documentation and/or other materials provided with the distribution. 92 * 3. All advertising materials mentioning features or use of this software 93 * must display the following acknowledgement: 94 * This product includes software developed by the NetBSD 95 * Foundation, Inc. and its contributors. 96 * 4. Neither the name of The NetBSD Foundation nor the names of its 97 * contributors may be used to endorse or promote products derived 98 * from this software without specific prior written permission. 99 * 100 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 101 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 102 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 103 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 104 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 105 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 106 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 107 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 108 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 109 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 110 * POSSIBILITY OF SUCH DAMAGE. 111 */ 112 113 /* 114 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995 115 * The Regents of the University of California. All rights reserved. 116 * 117 * Redistribution and use in source and binary forms, with or without 118 * modification, are permitted provided that the following conditions 119 * are met: 120 * 1. Redistributions of source code must retain the above copyright 121 * notice, this list of conditions and the following disclaimer. 122 * 2. Redistributions in binary form must reproduce the above copyright 123 * notice, this list of conditions and the following disclaimer in the 124 * documentation and/or other materials provided with the distribution. 125 * 3. Neither the name of the University nor the names of its contributors 126 * may be used to endorse or promote products derived from this software 127 * without specific prior written permission. 128 * 129 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 130 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 131 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 132 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 133 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 134 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 135 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 136 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 137 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 138 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 139 * SUCH DAMAGE. 140 * 141 * @(#)tcp_output.c 8.4 (Berkeley) 5/24/95 142 */ 143 144 #include <sys/cdefs.h> 145 __KERNEL_RCSID(0, "$NetBSD: tcp_output.c,v 1.162.12.2 2008/01/19 12:15:33 bouyer Exp $"); 146 147 #include "opt_inet.h" 148 #include "opt_ipsec.h" 149 #include "opt_tcp_debug.h" 150 151 #include <sys/param.h> 152 #include <sys/systm.h> 153 #include <sys/malloc.h> 154 #include <sys/mbuf.h> 155 #include <sys/protosw.h> 156 #include <sys/socket.h> 157 #include <sys/socketvar.h> 158 #include <sys/errno.h> 159 #include <sys/domain.h> 160 #include <sys/kernel.h> 161 #ifdef TCP_SIGNATURE 162 #include <sys/md5.h> 163 #endif 164 165 #include <net/if.h> 166 #include <net/route.h> 167 168 #include <netinet/in.h> 169 #include <netinet/in_systm.h> 170 #include <netinet/ip.h> 171 #include <netinet/in_pcb.h> 172 #include <netinet/ip_var.h> 173 174 #ifdef INET6 175 #ifndef INET 176 #include <netinet/in.h> 177 #endif 178 #include <netinet/ip6.h> 179 #include <netinet6/in6_var.h> 180 #include <netinet6/ip6_var.h> 181 #include <netinet6/in6_pcb.h> 182 #include <netinet6/nd6.h> 183 #endif 184 185 #ifdef FAST_IPSEC 186 #include <netipsec/ipsec.h> 187 #include <netipsec/key.h> 188 #ifdef INET6 189 #include <netipsec/ipsec6.h> 190 #endif 191 #endif /* FAST_IPSEC*/ 192 #ifdef IPSEC 193 #include <netinet6/ipsec.h> 194 #endif 195 196 #include <netinet/tcp.h> 197 #define TCPOUTFLAGS 198 #include <netinet/tcp_fsm.h> 199 #include <netinet/tcp_seq.h> 200 #include <netinet/tcp_timer.h> 201 #include <netinet/tcp_var.h> 202 #include <netinet/tcp_congctl.h> 203 #include <netinet/tcpip.h> 204 #include <netinet/tcp_debug.h> 205 #include <netinet/in_offload.h> 206 #include <netinet6/in6_offload.h> 207 208 #ifdef IPSEC 209 #include <netkey/key.h> 210 #endif 211 212 #ifdef notyet 213 extern struct mbuf *m_copypack(); 214 #endif 215 216 /* 217 * Knob to enable Congestion Window Monitoring, and control 218 * the burst size it allows. Default burst is 4 packets, per 219 * the Internet draft. 220 */ 221 int tcp_cwm = 0; 222 int tcp_cwm_burstsize = 4; 223 224 int tcp_do_autosndbuf = 0; 225 int tcp_autosndbuf_inc = 8 * 1024; 226 int tcp_autosndbuf_max = 256 * 1024; 227 228 #ifdef TCP_OUTPUT_COUNTERS 229 #include <sys/device.h> 230 231 extern struct evcnt tcp_output_bigheader; 232 extern struct evcnt tcp_output_predict_hit; 233 extern struct evcnt tcp_output_predict_miss; 234 extern struct evcnt tcp_output_copysmall; 235 extern struct evcnt tcp_output_copybig; 236 extern struct evcnt tcp_output_refbig; 237 238 #define TCP_OUTPUT_COUNTER_INCR(ev) (ev)->ev_count++ 239 #else 240 241 #define TCP_OUTPUT_COUNTER_INCR(ev) /* nothing */ 242 243 #endif /* TCP_OUTPUT_COUNTERS */ 244 245 static 246 #ifndef GPROF 247 inline 248 #endif 249 int 250 tcp_segsize(struct tcpcb *tp, int *txsegsizep, int *rxsegsizep, 251 bool *alwaysfragp) 252 { 253 #ifdef INET 254 struct inpcb *inp = tp->t_inpcb; 255 #endif 256 #ifdef INET6 257 struct in6pcb *in6p = tp->t_in6pcb; 258 #endif 259 struct socket *so = NULL; 260 struct rtentry *rt; 261 struct ifnet *ifp; 262 int size; 263 int hdrlen; 264 int optlen; 265 266 *alwaysfragp = false; 267 268 #ifdef DIAGNOSTIC 269 if (tp->t_inpcb && tp->t_in6pcb) 270 panic("tcp_segsize: both t_inpcb and t_in6pcb are set"); 271 #endif 272 switch (tp->t_family) { 273 #ifdef INET 274 case AF_INET: 275 hdrlen = sizeof(struct ip) + sizeof(struct tcphdr); 276 break; 277 #endif 278 #ifdef INET6 279 case AF_INET6: 280 hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 281 break; 282 #endif 283 default: 284 size = tcp_mssdflt; 285 goto out; 286 } 287 288 rt = NULL; 289 #ifdef INET 290 if (inp) { 291 rt = in_pcbrtentry(inp); 292 so = inp->inp_socket; 293 } 294 #endif 295 #ifdef INET6 296 if (in6p) { 297 rt = in6_pcbrtentry(in6p); 298 so = in6p->in6p_socket; 299 } 300 #endif 301 if (rt == NULL) { 302 size = tcp_mssdflt; 303 goto out; 304 } 305 306 ifp = rt->rt_ifp; 307 308 size = tcp_mssdflt; 309 if (tp->t_mtudisc && rt->rt_rmx.rmx_mtu != 0) { 310 #ifdef INET6 311 if (in6p && rt->rt_rmx.rmx_mtu < IPV6_MMTU) { 312 /* 313 * RFC2460 section 5, last paragraph: if path MTU is 314 * smaller than 1280, use 1280 as packet size and 315 * attach fragment header. 316 */ 317 size = IPV6_MMTU - hdrlen - sizeof(struct ip6_frag); 318 *alwaysfragp = true; 319 } else 320 size = rt->rt_rmx.rmx_mtu - hdrlen; 321 #else 322 size = rt->rt_rmx.rmx_mtu - hdrlen; 323 #endif 324 } else if (ifp->if_flags & IFF_LOOPBACK) 325 size = ifp->if_mtu - hdrlen; 326 #ifdef INET 327 else if (inp && tp->t_mtudisc) 328 size = ifp->if_mtu - hdrlen; 329 else if (inp && in_localaddr(inp->inp_faddr)) 330 size = ifp->if_mtu - hdrlen; 331 #endif 332 #ifdef INET6 333 else if (in6p) { 334 #ifdef INET 335 if (IN6_IS_ADDR_V4MAPPED(&in6p->in6p_faddr)) { 336 /* mapped addr case */ 337 struct in_addr d; 338 bcopy(&in6p->in6p_faddr.s6_addr32[3], &d, sizeof(d)); 339 if (tp->t_mtudisc || in_localaddr(d)) 340 size = ifp->if_mtu - hdrlen; 341 } else 342 #endif 343 { 344 /* 345 * for IPv6, path MTU discovery is always turned on, 346 * or the node must use packet size <= 1280. 347 */ 348 size = tp->t_mtudisc ? IN6_LINKMTU(ifp) : IPV6_MMTU; 349 size -= hdrlen; 350 } 351 } 352 #endif 353 out: 354 /* 355 * Now we must make room for whatever extra TCP/IP options are in 356 * the packet. 357 */ 358 optlen = tcp_optlen(tp); 359 360 /* 361 * XXX tp->t_ourmss should have the right size, but without this code 362 * fragmentation will occur... need more investigation 363 */ 364 #ifdef INET 365 if (inp) { 366 #if defined(IPSEC) || defined(FAST_IPSEC) 367 if (! IPSEC_PCB_SKIP_IPSEC(inp->inp_sp, IPSEC_DIR_OUTBOUND)) 368 optlen += ipsec4_hdrsiz_tcp(tp); 369 #endif 370 optlen += ip_optlen(inp); 371 } 372 #endif 373 #ifdef INET6 374 #ifdef INET 375 if (in6p && tp->t_family == AF_INET) { 376 #if defined(IPSEC) || defined(FAST_IPSEC) 377 if (! IPSEC_PCB_SKIP_IPSEC(in6p->in6p_sp, IPSEC_DIR_OUTBOUND)) 378 optlen += ipsec4_hdrsiz_tcp(tp); 379 #endif 380 /* XXX size -= ip_optlen(in6p); */ 381 } else 382 #endif 383 if (in6p && tp->t_family == AF_INET6) { 384 #if defined(IPSEC) || defined(FAST_IPSEC) 385 if (! IPSEC_PCB_SKIP_IPSEC(in6p->in6p_sp, IPSEC_DIR_OUTBOUND)) 386 optlen += ipsec6_hdrsiz_tcp(tp); 387 #endif 388 optlen += ip6_optlen(in6p); 389 } 390 #endif 391 size -= optlen; 392 393 /* there may not be any room for data if mtu is too small */ 394 if (size < 0) 395 return (EMSGSIZE); 396 397 /* 398 * *rxsegsizep holds *estimated* inbound segment size (estimation 399 * assumes that path MTU is the same for both ways). this is only 400 * for silly window avoidance, do not use the value for other purposes. 401 * 402 * ipseclen is subtracted from both sides, this may not be right. 403 * I'm not quite sure about this (could someone comment). 404 */ 405 *txsegsizep = min(tp->t_peermss - optlen, size); 406 /* 407 * Never send more than half a buffer full. This insures that we can 408 * always keep 2 packets on the wire, no matter what SO_SNDBUF is, and 409 * therefore acks will never be delayed unless we run out of data to 410 * transmit. 411 */ 412 if (so) 413 *txsegsizep = min(so->so_snd.sb_hiwat >> 1, *txsegsizep); 414 *rxsegsizep = min(tp->t_ourmss - optlen, size); 415 416 if (*txsegsizep != tp->t_segsz) { 417 /* 418 * If the new segment size is larger, we don't want to 419 * mess up the congestion window, but if it is smaller 420 * we'll have to reduce the congestion window to ensure 421 * that we don't get into trouble with initial windows 422 * and the rest. In any case, if the segment size 423 * has changed, chances are the path has, too, and 424 * our congestion window will be different. 425 */ 426 if (*txsegsizep < tp->t_segsz) { 427 tp->snd_cwnd = max((tp->snd_cwnd / tp->t_segsz) 428 * *txsegsizep, *txsegsizep); 429 tp->snd_ssthresh = max((tp->snd_ssthresh / tp->t_segsz) 430 * *txsegsizep, *txsegsizep); 431 } 432 tp->t_segsz = *txsegsizep; 433 } 434 435 return (0); 436 } 437 438 static 439 #ifndef GPROF 440 inline 441 #endif 442 int 443 tcp_build_datapkt(struct tcpcb *tp, struct socket *so, int off, 444 long len, int hdrlen, struct mbuf **mp) 445 { 446 struct mbuf *m, *m0; 447 448 if (tp->t_force && len == 1) 449 tcpstat.tcps_sndprobe++; 450 else if (SEQ_LT(tp->snd_nxt, tp->snd_max)) { 451 tcpstat.tcps_sndrexmitpack++; 452 tcpstat.tcps_sndrexmitbyte += len; 453 } else { 454 tcpstat.tcps_sndpack++; 455 tcpstat.tcps_sndbyte += len; 456 } 457 #ifdef notyet 458 if ((m = m_copypack(so->so_snd.sb_mb, off, 459 (int)len, max_linkhdr + hdrlen)) == 0) 460 return (ENOBUFS); 461 /* 462 * m_copypack left space for our hdr; use it. 463 */ 464 m->m_len += hdrlen; 465 m->m_data -= hdrlen; 466 #else 467 MGETHDR(m, M_DONTWAIT, MT_HEADER); 468 if (__predict_false(m == NULL)) 469 return (ENOBUFS); 470 MCLAIM(m, &tcp_tx_mowner); 471 472 /* 473 * XXX Because other code assumes headers will fit in 474 * XXX one header mbuf. 475 * 476 * (This code should almost *never* be run.) 477 */ 478 if (__predict_false((max_linkhdr + hdrlen) > MHLEN)) { 479 TCP_OUTPUT_COUNTER_INCR(&tcp_output_bigheader); 480 MCLGET(m, M_DONTWAIT); 481 if ((m->m_flags & M_EXT) == 0) { 482 m_freem(m); 483 return (ENOBUFS); 484 } 485 } 486 487 m->m_data += max_linkhdr; 488 m->m_len = hdrlen; 489 490 /* 491 * To avoid traversing the whole sb_mb chain for correct 492 * data to send, remember last sent mbuf, its offset and 493 * the sent size. When called the next time, see if the 494 * data to send is directly following the previous transfer. 495 * This is important for large TCP windows. 496 */ 497 if (off == 0 || tp->t_lastm == NULL || 498 (tp->t_lastoff + tp->t_lastlen) != off) { 499 TCP_OUTPUT_COUNTER_INCR(&tcp_output_predict_miss); 500 /* 501 * Either a new packet or a retransmit. 502 * Start from the beginning. 503 */ 504 tp->t_lastm = so->so_snd.sb_mb; 505 tp->t_inoff = off; 506 } else { 507 TCP_OUTPUT_COUNTER_INCR(&tcp_output_predict_hit); 508 tp->t_inoff += tp->t_lastlen; 509 } 510 511 /* Traverse forward to next packet */ 512 while (tp->t_inoff > 0) { 513 if (tp->t_lastm == NULL) 514 panic("tp->t_lastm == NULL"); 515 if (tp->t_inoff < tp->t_lastm->m_len) 516 break; 517 tp->t_inoff -= tp->t_lastm->m_len; 518 tp->t_lastm = tp->t_lastm->m_next; 519 } 520 521 tp->t_lastoff = off; 522 tp->t_lastlen = len; 523 m0 = tp->t_lastm; 524 off = tp->t_inoff; 525 526 if (len <= M_TRAILINGSPACE(m)) { 527 m_copydata(m0, off, (int) len, mtod(m, char *) + hdrlen); 528 m->m_len += len; 529 TCP_OUTPUT_COUNTER_INCR(&tcp_output_copysmall); 530 } else { 531 m->m_next = m_copym(m0, off, (int) len, M_DONTWAIT); 532 if (m->m_next == NULL) { 533 m_freem(m); 534 return (ENOBUFS); 535 } 536 #ifdef TCP_OUTPUT_COUNTERS 537 if (m->m_next->m_flags & M_EXT) 538 TCP_OUTPUT_COUNTER_INCR(&tcp_output_refbig); 539 else 540 TCP_OUTPUT_COUNTER_INCR(&tcp_output_copybig); 541 #endif /* TCP_OUTPUT_COUNTERS */ 542 } 543 #endif 544 545 *mp = m; 546 return (0); 547 } 548 549 /* 550 * Tcp output routine: figure out what should be sent and send it. 551 */ 552 int 553 tcp_output(struct tcpcb *tp) 554 { 555 struct rtentry *rt; 556 struct socket *so; 557 struct route *ro; 558 long len, win; 559 int off, flags, error; 560 struct mbuf *m; 561 struct ip *ip; 562 #ifdef INET6 563 struct ip6_hdr *ip6; 564 #endif 565 struct tcphdr *th; 566 u_char opt[MAX_TCPOPTLEN]; 567 unsigned optlen, hdrlen, packetlen; 568 unsigned int sack_numblks; 569 int idle, sendalot, txsegsize, rxsegsize; 570 int txsegsize_nosack; 571 int maxburst = TCP_MAXBURST; 572 int af; /* address family on the wire */ 573 int iphdrlen; 574 int has_tso4, has_tso6; 575 int has_tso, use_tso; 576 bool alwaysfrag; 577 int sack_rxmit; 578 int sack_bytes_rxmt; 579 struct sackhole *p; 580 #ifdef TCP_SIGNATURE 581 int sigoff = 0; 582 #endif 583 584 #ifdef DIAGNOSTIC 585 if (tp->t_inpcb && tp->t_in6pcb) 586 panic("tcp_output: both t_inpcb and t_in6pcb are set"); 587 #endif 588 so = NULL; 589 ro = NULL; 590 if (tp->t_inpcb) { 591 so = tp->t_inpcb->inp_socket; 592 ro = &tp->t_inpcb->inp_route; 593 } 594 #ifdef INET6 595 else if (tp->t_in6pcb) { 596 so = tp->t_in6pcb->in6p_socket; 597 ro = &tp->t_in6pcb->in6p_route; 598 } 599 #endif 600 601 switch (af = tp->t_family) { 602 #ifdef INET 603 case AF_INET: 604 if (tp->t_inpcb) 605 break; 606 #ifdef INET6 607 /* mapped addr case */ 608 if (tp->t_in6pcb) 609 break; 610 #endif 611 return (EINVAL); 612 #endif 613 #ifdef INET6 614 case AF_INET6: 615 if (tp->t_in6pcb) 616 break; 617 return (EINVAL); 618 #endif 619 default: 620 return (EAFNOSUPPORT); 621 } 622 623 if (tcp_segsize(tp, &txsegsize, &rxsegsize, &alwaysfrag)) 624 return (EMSGSIZE); 625 626 idle = (tp->snd_max == tp->snd_una); 627 628 /* 629 * Determine if we can use TCP segmentation offload: 630 * - If we're using IPv4 631 * - If there is not an IPsec policy that prevents it 632 * - If the interface can do it 633 */ 634 has_tso4 = has_tso6 = false; 635 #if defined(INET) 636 has_tso4 = tp->t_inpcb != NULL && 637 #if defined(IPSEC) || defined(FAST_IPSEC) 638 IPSEC_PCB_SKIP_IPSEC(tp->t_inpcb->inp_sp, 639 IPSEC_DIR_OUTBOUND) && 640 #endif 641 (rt = rtcache_validate(&tp->t_inpcb->inp_route)) != NULL && 642 (rt->rt_ifp->if_capenable & IFCAP_TSOv4) != 0; 643 #endif /* defined(INET) */ 644 #if defined(INET6) 645 has_tso6 = tp->t_in6pcb != NULL && 646 #if defined(IPSEC) || defined(FAST_IPSEC) 647 IPSEC_PCB_SKIP_IPSEC(tp->t_in6pcb->in6p_sp, 648 IPSEC_DIR_OUTBOUND) && 649 #endif 650 (rt = rtcache_validate(&tp->t_in6pcb->in6p_route)) != NULL && 651 (rt->rt_ifp->if_capenable & IFCAP_TSOv6) != 0; 652 #endif /* defined(INET6) */ 653 has_tso = (has_tso4 || has_tso6) && !alwaysfrag; 654 655 /* 656 * Restart Window computation. From draft-floyd-incr-init-win-03: 657 * 658 * Optionally, a TCP MAY set the restart window to the 659 * minimum of the value used for the initial window and 660 * the current value of cwnd (in other words, using a 661 * larger value for the restart window should never increase 662 * the size of cwnd). 663 */ 664 if (tcp_cwm) { 665 /* 666 * Hughes/Touch/Heidemann Congestion Window Monitoring. 667 * Count the number of packets currently pending 668 * acknowledgement, and limit our congestion window 669 * to a pre-determined allowed burst size plus that count. 670 * This prevents bursting once all pending packets have 671 * been acknowledged (i.e. transmission is idle). 672 * 673 * XXX Link this to Initial Window? 674 */ 675 tp->snd_cwnd = min(tp->snd_cwnd, 676 (tcp_cwm_burstsize * txsegsize) + 677 (tp->snd_nxt - tp->snd_una)); 678 } else { 679 if (idle && (tcp_now - tp->t_rcvtime) >= tp->t_rxtcur) { 680 /* 681 * We have been idle for "a while" and no acks are 682 * expected to clock out any data we send -- 683 * slow start to get ack "clock" running again. 684 */ 685 int ss = tcp_init_win; 686 #ifdef INET 687 if (tp->t_inpcb && 688 in_localaddr(tp->t_inpcb->inp_faddr)) 689 ss = tcp_init_win_local; 690 #endif 691 #ifdef INET6 692 if (tp->t_in6pcb && 693 in6_localaddr(&tp->t_in6pcb->in6p_faddr)) 694 ss = tcp_init_win_local; 695 #endif 696 tp->snd_cwnd = min(tp->snd_cwnd, 697 TCP_INITIAL_WINDOW(ss, txsegsize)); 698 } 699 } 700 701 txsegsize_nosack = txsegsize; 702 again: 703 use_tso = has_tso; 704 if ((tp->t_flags & (TF_ECN_SND_CWR|TF_ECN_SND_ECE)) != 0) { 705 /* don't duplicate CWR/ECE. */ 706 use_tso = 0; 707 } 708 TCP_REASS_LOCK(tp); 709 sack_numblks = tcp_sack_numblks(tp); 710 if (sack_numblks) { 711 int sackoptlen; 712 713 sackoptlen = TCP_SACK_OPTLEN(sack_numblks); 714 if (sackoptlen > txsegsize_nosack) { 715 sack_numblks = 0; /* give up SACK */ 716 txsegsize = txsegsize_nosack; 717 } else { 718 if ((tp->rcv_sack_flags & TCPSACK_HAVED) != 0) { 719 /* don't duplicate D-SACK. */ 720 use_tso = 0; 721 } 722 txsegsize = txsegsize_nosack - sackoptlen; 723 } 724 } else { 725 txsegsize = txsegsize_nosack; 726 } 727 728 /* 729 * Determine length of data that should be transmitted, and 730 * flags that should be used. If there is some data or critical 731 * controls (SYN, RST) to send, then transmit; otherwise, 732 * investigate further. 733 * 734 * Readjust SACK information to avoid resending duplicate data. 735 */ 736 if (TCP_SACK_ENABLED(tp) && SEQ_LT(tp->snd_nxt, tp->snd_max)) 737 tcp_sack_adjust(tp); 738 sendalot = 0; 739 off = tp->snd_nxt - tp->snd_una; 740 win = min(tp->snd_wnd, tp->snd_cwnd); 741 742 flags = tcp_outflags[tp->t_state]; 743 744 /* 745 * Send any SACK-generated retransmissions. If we're explicitly trying 746 * to send out new data (when sendalot is 1), bypass this function. 747 * If we retransmit in fast recovery mode, decrement snd_cwnd, since 748 * we're replacing a (future) new transmission with a retransmission 749 * now, and we previously incremented snd_cwnd in tcp_input(). 750 */ 751 /* 752 * Still in sack recovery , reset rxmit flag to zero. 753 */ 754 sack_rxmit = 0; 755 sack_bytes_rxmt = 0; 756 len = 0; 757 p = NULL; 758 do { 759 long cwin; 760 if (!TCP_SACK_ENABLED(tp)) 761 break; 762 if (tp->t_partialacks < 0) 763 break; 764 p = tcp_sack_output(tp, &sack_bytes_rxmt); 765 if (p == NULL) 766 break; 767 768 cwin = min(tp->snd_wnd, tp->snd_cwnd) - sack_bytes_rxmt; 769 if (cwin < 0) 770 cwin = 0; 771 /* Do not retransmit SACK segments beyond snd_recover */ 772 if (SEQ_GT(p->end, tp->snd_recover)) { 773 /* 774 * (At least) part of sack hole extends beyond 775 * snd_recover. Check to see if we can rexmit data 776 * for this hole. 777 */ 778 if (SEQ_GEQ(p->rxmit, tp->snd_recover)) { 779 /* 780 * Can't rexmit any more data for this hole. 781 * That data will be rexmitted in the next 782 * sack recovery episode, when snd_recover 783 * moves past p->rxmit. 784 */ 785 p = NULL; 786 break; 787 } 788 /* Can rexmit part of the current hole */ 789 len = ((long)ulmin(cwin, tp->snd_recover - p->rxmit)); 790 } else 791 len = ((long)ulmin(cwin, p->end - p->rxmit)); 792 off = p->rxmit - tp->snd_una; 793 if (off + len > so->so_snd.sb_cc) { 794 /* 1 for TH_FIN */ 795 KASSERT(off + len == so->so_snd.sb_cc + 1); 796 KASSERT(p->rxmit + len == tp->snd_max); 797 len = so->so_snd.sb_cc - off; 798 } 799 if (len > 0) { 800 sack_rxmit = 1; 801 sendalot = 1; 802 } 803 } while (/*CONSTCOND*/0); 804 805 /* 806 * If in persist timeout with window of 0, send 1 byte. 807 * Otherwise, if window is small but nonzero 808 * and timer expired, we will send what we can 809 * and go to transmit state. 810 */ 811 if (tp->t_force) { 812 if (win == 0) { 813 /* 814 * If we still have some data to send, then 815 * clear the FIN bit. Usually this would 816 * happen below when it realizes that we 817 * aren't sending all the data. However, 818 * if we have exactly 1 byte of unset data, 819 * then it won't clear the FIN bit below, 820 * and if we are in persist state, we wind 821 * up sending the packet without recording 822 * that we sent the FIN bit. 823 * 824 * We can't just blindly clear the FIN bit, 825 * because if we don't have any more data 826 * to send then the probe will be the FIN 827 * itself. 828 */ 829 if (off < so->so_snd.sb_cc) 830 flags &= ~TH_FIN; 831 win = 1; 832 } else { 833 TCP_TIMER_DISARM(tp, TCPT_PERSIST); 834 tp->t_rxtshift = 0; 835 } 836 } 837 838 if (sack_rxmit == 0) { 839 if (TCP_SACK_ENABLED(tp) && tp->t_partialacks >= 0) { 840 long cwin; 841 842 /* 843 * We are inside of a SACK recovery episode and are 844 * sending new data, having retransmitted all the 845 * data possible in the scoreboard. 846 */ 847 if (tp->snd_wnd < so->so_snd.sb_cc) { 848 len = tp->snd_wnd - off; 849 flags &= ~TH_FIN; 850 } else { 851 len = so->so_snd.sb_cc - off; 852 } 853 854 /* 855 * From FreeBSD: 856 * Don't remove this (len > 0) check ! 857 * We explicitly check for len > 0 here (although it 858 * isn't really necessary), to work around a gcc 859 * optimization issue - to force gcc to compute 860 * len above. Without this check, the computation 861 * of len is bungled by the optimizer. 862 */ 863 if (len > 0) { 864 cwin = tp->snd_cwnd - 865 (tp->snd_nxt - tp->sack_newdata) - 866 sack_bytes_rxmt; 867 if (cwin < 0) 868 cwin = 0; 869 if (cwin < len) { 870 len = cwin; 871 flags &= ~TH_FIN; 872 } 873 } 874 } else if (win < so->so_snd.sb_cc) { 875 len = win - off; 876 flags &= ~TH_FIN; 877 } else { 878 len = so->so_snd.sb_cc - off; 879 } 880 } 881 882 if (len < 0) { 883 /* 884 * If FIN has been sent but not acked, 885 * but we haven't been called to retransmit, 886 * len will be -1. Otherwise, window shrank 887 * after we sent into it. If window shrank to 0, 888 * cancel pending retransmit, pull snd_nxt back 889 * to (closed) window, and set the persist timer 890 * if it isn't already going. If the window didn't 891 * close completely, just wait for an ACK. 892 * 893 * If we have a pending FIN, either it has already been 894 * transmitted or it is outside the window, so drop it. 895 * If the FIN has been transmitted, but this is not a 896 * retransmission, then len must be -1. Therefore we also 897 * prevent here the sending of `gratuitous FINs'. This 898 * eliminates the need to check for that case below (e.g. 899 * to back up snd_nxt before the FIN so that the sequence 900 * number is correct). 901 */ 902 len = 0; 903 flags &= ~TH_FIN; 904 if (win == 0) { 905 TCP_TIMER_DISARM(tp, TCPT_REXMT); 906 tp->t_rxtshift = 0; 907 tp->snd_nxt = tp->snd_una; 908 if (TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) 909 tcp_setpersist(tp); 910 } 911 } 912 913 /* 914 * Automatic sizing enables the performance of large buffers 915 * and most of the efficiency of small ones by only allocating 916 * space when it is needed. 917 * 918 * The criteria to step up the send buffer one notch are: 919 * 1. receive window of remote host is larger than send buffer 920 * (with a fudge factor of 5/4th); 921 * 2. send buffer is filled to 7/8th with data (so we actually 922 * have data to make use of it); 923 * 3. send buffer fill has not hit maximal automatic size; 924 * 4. our send window (slow start and cogestion controlled) is 925 * larger than sent but unacknowledged data in send buffer. 926 * 927 * The remote host receive window scaling factor may limit the 928 * growing of the send buffer before it reaches its allowed 929 * maximum. 930 * 931 * It scales directly with slow start or congestion window 932 * and does at most one step per received ACK. This fast 933 * scaling has the drawback of growing the send buffer beyond 934 * what is strictly necessary to make full use of a given 935 * delay*bandwith product. However testing has shown this not 936 * to be much of an problem. At worst we are trading wasting 937 * of available bandwith (the non-use of it) for wasting some 938 * socket buffer memory. 939 * 940 * TODO: Shrink send buffer during idle periods together 941 * with congestion window. Requires another timer. 942 */ 943 if (tcp_do_autosndbuf && so->so_snd.sb_flags & SB_AUTOSIZE) { 944 if ((tp->snd_wnd / 4 * 5) >= so->so_snd.sb_hiwat && 945 so->so_snd.sb_cc >= (so->so_snd.sb_hiwat / 8 * 7) && 946 so->so_snd.sb_cc < tcp_autosndbuf_max && 947 win >= (so->so_snd.sb_cc - (tp->snd_nxt - tp->snd_una))) { 948 if (!sbreserve(&so->so_snd, 949 min(so->so_snd.sb_hiwat + tcp_autosndbuf_inc, 950 tcp_autosndbuf_max), so)) 951 so->so_snd.sb_flags &= ~SB_AUTOSIZE; 952 } 953 } 954 955 if (len > txsegsize) { 956 if (use_tso) { 957 /* 958 * Truncate TSO transfers to IP_MAXPACKET, and make 959 * sure that we send equal size transfers down the 960 * stack (rather than big-small-big-small-...). 961 */ 962 #ifdef INET6 963 #if IPV6_MAXPACKET != IP_MAXPACKET 964 #error IPV6_MAXPACKET != IP_MAXPACKET 965 #endif 966 #endif 967 len = (min(len, IP_MAXPACKET) / txsegsize) * txsegsize; 968 if (len <= txsegsize) { 969 use_tso = 0; 970 } 971 } else 972 len = txsegsize; 973 flags &= ~TH_FIN; 974 sendalot = 1; 975 } else 976 use_tso = 0; 977 if (sack_rxmit) { 978 if (SEQ_LT(p->rxmit + len, tp->snd_una + so->so_snd.sb_cc)) 979 flags &= ~TH_FIN; 980 } 981 982 win = sbspace(&so->so_rcv); 983 984 /* 985 * Sender silly window avoidance. If connection is idle 986 * and can send all data, a maximum segment, 987 * at least a maximum default-size segment do it, 988 * or are forced, do it; otherwise don't bother. 989 * If peer's buffer is tiny, then send 990 * when window is at least half open. 991 * If retransmitting (possibly after persist timer forced us 992 * to send into a small window), then must resend. 993 */ 994 if (len) { 995 if (len >= txsegsize) 996 goto send; 997 if ((so->so_state & SS_MORETOCOME) == 0 && 998 ((idle || tp->t_flags & TF_NODELAY) && 999 len + off >= so->so_snd.sb_cc)) 1000 goto send; 1001 if (tp->t_force) 1002 goto send; 1003 if (len >= tp->max_sndwnd / 2) 1004 goto send; 1005 if (SEQ_LT(tp->snd_nxt, tp->snd_max)) 1006 goto send; 1007 if (sack_rxmit) 1008 goto send; 1009 } 1010 1011 /* 1012 * Compare available window to amount of window known to peer 1013 * (as advertised window less next expected input). If the 1014 * difference is at least twice the size of the largest segment 1015 * we expect to receive (i.e. two segments) or at least 50% of 1016 * the maximum possible window, then want to send a window update 1017 * to peer. 1018 */ 1019 if (win > 0) { 1020 /* 1021 * "adv" is the amount we can increase the window, 1022 * taking into account that we are limited by 1023 * TCP_MAXWIN << tp->rcv_scale. 1024 */ 1025 long adv = min(win, (long)TCP_MAXWIN << tp->rcv_scale) - 1026 (tp->rcv_adv - tp->rcv_nxt); 1027 1028 if (adv >= (long) (2 * rxsegsize)) 1029 goto send; 1030 if (2 * adv >= (long) so->so_rcv.sb_hiwat) 1031 goto send; 1032 } 1033 1034 /* 1035 * Send if we owe peer an ACK. 1036 */ 1037 if (tp->t_flags & TF_ACKNOW) 1038 goto send; 1039 if (flags & (TH_SYN|TH_FIN|TH_RST)) 1040 goto send; 1041 if (SEQ_GT(tp->snd_up, tp->snd_una)) 1042 goto send; 1043 /* 1044 * In SACK, it is possible for tcp_output to fail to send a segment 1045 * after the retransmission timer has been turned off. Make sure 1046 * that the retransmission timer is set. 1047 */ 1048 if (TCP_SACK_ENABLED(tp) && SEQ_GT(tp->snd_max, tp->snd_una) && 1049 !TCP_TIMER_ISARMED(tp, TCPT_REXMT) && 1050 !TCP_TIMER_ISARMED(tp, TCPT_PERSIST)) { 1051 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 1052 goto just_return; 1053 } 1054 1055 /* 1056 * TCP window updates are not reliable, rather a polling protocol 1057 * using ``persist'' packets is used to insure receipt of window 1058 * updates. The three ``states'' for the output side are: 1059 * idle not doing retransmits or persists 1060 * persisting to move a small or zero window 1061 * (re)transmitting and thereby not persisting 1062 * 1063 * tp->t_timer[TCPT_PERSIST] 1064 * is set when we are in persist state. 1065 * tp->t_force 1066 * is set when we are called to send a persist packet. 1067 * tp->t_timer[TCPT_REXMT] 1068 * is set when we are retransmitting 1069 * The output side is idle when both timers are zero. 1070 * 1071 * If send window is too small, there is data to transmit, and no 1072 * retransmit or persist is pending, then go to persist state. 1073 * If nothing happens soon, send when timer expires: 1074 * if window is nonzero, transmit what we can, 1075 * otherwise force out a byte. 1076 */ 1077 if (so->so_snd.sb_cc && TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 && 1078 TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) { 1079 tp->t_rxtshift = 0; 1080 tcp_setpersist(tp); 1081 } 1082 1083 /* 1084 * No reason to send a segment, just return. 1085 */ 1086 just_return: 1087 TCP_REASS_UNLOCK(tp); 1088 return (0); 1089 1090 send: 1091 /* 1092 * Before ESTABLISHED, force sending of initial options 1093 * unless TCP set not to do any options. 1094 * NOTE: we assume that the IP/TCP header plus TCP options 1095 * always fit in a single mbuf, leaving room for a maximum 1096 * link header, i.e. 1097 * max_linkhdr + sizeof (struct tcpiphdr) + optlen <= MCLBYTES 1098 */ 1099 optlen = 0; 1100 switch (af) { 1101 #ifdef INET 1102 case AF_INET: 1103 iphdrlen = sizeof(struct ip) + sizeof(struct tcphdr); 1104 break; 1105 #endif 1106 #ifdef INET6 1107 case AF_INET6: 1108 iphdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 1109 break; 1110 #endif 1111 default: /*pacify gcc*/ 1112 iphdrlen = 0; 1113 break; 1114 } 1115 hdrlen = iphdrlen; 1116 if (flags & TH_SYN) { 1117 struct rtentry *synrt; 1118 1119 synrt = NULL; 1120 #ifdef INET 1121 if (tp->t_inpcb) 1122 synrt = in_pcbrtentry(tp->t_inpcb); 1123 #endif 1124 #ifdef INET6 1125 if (tp->t_in6pcb) 1126 synrt = in6_pcbrtentry(tp->t_in6pcb); 1127 #endif 1128 1129 tp->snd_nxt = tp->iss; 1130 tp->t_ourmss = tcp_mss_to_advertise(synrt != NULL ? 1131 synrt->rt_ifp : NULL, af); 1132 if ((tp->t_flags & TF_NOOPT) == 0) { 1133 opt[0] = TCPOPT_MAXSEG; 1134 opt[1] = 4; 1135 opt[2] = (tp->t_ourmss >> 8) & 0xff; 1136 opt[3] = tp->t_ourmss & 0xff; 1137 optlen = 4; 1138 1139 if ((tp->t_flags & TF_REQ_SCALE) && 1140 ((flags & TH_ACK) == 0 || 1141 (tp->t_flags & TF_RCVD_SCALE))) { 1142 *((u_int32_t *) (opt + optlen)) = htonl( 1143 TCPOPT_NOP << 24 | 1144 TCPOPT_WINDOW << 16 | 1145 TCPOLEN_WINDOW << 8 | 1146 tp->request_r_scale); 1147 optlen += 4; 1148 } 1149 if (tcp_do_sack) { 1150 u_int8_t *cp = (u_int8_t *)(opt + optlen); 1151 1152 cp[0] = TCPOPT_SACK_PERMITTED; 1153 cp[1] = 2; 1154 cp[2] = TCPOPT_NOP; 1155 cp[3] = TCPOPT_NOP; 1156 optlen += 4; 1157 } 1158 } 1159 } 1160 1161 /* 1162 * Send a timestamp and echo-reply if this is a SYN and our side 1163 * wants to use timestamps (TF_REQ_TSTMP is set) or both our side 1164 * and our peer have sent timestamps in our SYN's. 1165 */ 1166 if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP && 1167 (flags & TH_RST) == 0 && 1168 ((flags & (TH_SYN|TH_ACK)) == TH_SYN || 1169 (tp->t_flags & TF_RCVD_TSTMP))) { 1170 u_int32_t *lp = (u_int32_t *)(opt + optlen); 1171 1172 /* Form timestamp option as shown in appendix A of RFC 1323. */ 1173 *lp++ = htonl(TCPOPT_TSTAMP_HDR); 1174 *lp++ = htonl(TCP_TIMESTAMP(tp)); 1175 *lp = htonl(tp->ts_recent); 1176 optlen += TCPOLEN_TSTAMP_APPA; 1177 1178 /* Set receive buffer autosizing timestamp. */ 1179 if (tp->rfbuf_ts == 0 && (so->so_rcv.sb_flags & SB_AUTOSIZE)) 1180 tp->rfbuf_ts = TCP_TIMESTAMP(tp); 1181 } 1182 1183 /* 1184 * Tack on the SACK block if it is necessary. 1185 */ 1186 if (sack_numblks) { 1187 int sack_len; 1188 u_char *bp = (u_char *)(opt + optlen); 1189 u_int32_t *lp = (u_int32_t *)(bp + 4); 1190 struct ipqent *tiqe; 1191 1192 sack_len = sack_numblks * 8 + 2; 1193 bp[0] = TCPOPT_NOP; 1194 bp[1] = TCPOPT_NOP; 1195 bp[2] = TCPOPT_SACK; 1196 bp[3] = sack_len; 1197 if ((tp->rcv_sack_flags & TCPSACK_HAVED) != 0) { 1198 sack_numblks--; 1199 *lp++ = htonl(tp->rcv_dsack_block.left); 1200 *lp++ = htonl(tp->rcv_dsack_block.right); 1201 tp->rcv_sack_flags &= ~TCPSACK_HAVED; 1202 } 1203 for (tiqe = TAILQ_FIRST(&tp->timeq); 1204 sack_numblks > 0; tiqe = TAILQ_NEXT(tiqe, ipqe_timeq)) { 1205 KASSERT(tiqe != NULL); 1206 sack_numblks--; 1207 *lp++ = htonl(tiqe->ipqe_seq); 1208 *lp++ = htonl(tiqe->ipqe_seq + tiqe->ipqe_len + 1209 ((tiqe->ipqe_flags & TH_FIN) != 0 ? 1 : 0)); 1210 } 1211 optlen += sack_len + 2; 1212 } 1213 TCP_REASS_UNLOCK(tp); 1214 1215 #ifdef TCP_SIGNATURE 1216 if (tp->t_flags & TF_SIGNATURE) { 1217 u_char *bp; 1218 /* 1219 * Initialize TCP-MD5 option (RFC2385) 1220 */ 1221 bp = (u_char *)opt + optlen; 1222 *bp++ = TCPOPT_SIGNATURE; 1223 *bp++ = TCPOLEN_SIGNATURE; 1224 sigoff = optlen + 2; 1225 bzero(bp, TCP_SIGLEN); 1226 bp += TCP_SIGLEN; 1227 optlen += TCPOLEN_SIGNATURE; 1228 /* 1229 * Terminate options list and maintain 32-bit alignment. 1230 */ 1231 *bp++ = TCPOPT_NOP; 1232 *bp++ = TCPOPT_EOL; 1233 optlen += 2; 1234 } 1235 #endif /* TCP_SIGNATURE */ 1236 1237 hdrlen += optlen; 1238 1239 #ifdef DIAGNOSTIC 1240 if (!use_tso && len > txsegsize) 1241 panic("tcp data to be sent is larger than segment"); 1242 else if (use_tso && len > IP_MAXPACKET) 1243 panic("tcp data to be sent is larger than max TSO size"); 1244 if (max_linkhdr + hdrlen > MCLBYTES) 1245 panic("tcphdr too big"); 1246 #endif 1247 1248 /* 1249 * Grab a header mbuf, attaching a copy of data to 1250 * be transmitted, and initialize the header from 1251 * the template for sends on this connection. 1252 */ 1253 if (len) { 1254 error = tcp_build_datapkt(tp, so, off, len, hdrlen, &m); 1255 if (error) 1256 goto out; 1257 /* 1258 * If we're sending everything we've got, set PUSH. 1259 * (This will keep happy those implementations which only 1260 * give data to the user when a buffer fills or 1261 * a PUSH comes in.) 1262 */ 1263 if (off + len == so->so_snd.sb_cc) 1264 flags |= TH_PUSH; 1265 } else { 1266 if (tp->t_flags & TF_ACKNOW) 1267 tcpstat.tcps_sndacks++; 1268 else if (flags & (TH_SYN|TH_FIN|TH_RST)) 1269 tcpstat.tcps_sndctrl++; 1270 else if (SEQ_GT(tp->snd_up, tp->snd_una)) 1271 tcpstat.tcps_sndurg++; 1272 else 1273 tcpstat.tcps_sndwinup++; 1274 1275 MGETHDR(m, M_DONTWAIT, MT_HEADER); 1276 if (m != NULL && max_linkhdr + hdrlen > MHLEN) { 1277 MCLGET(m, M_DONTWAIT); 1278 if ((m->m_flags & M_EXT) == 0) { 1279 m_freem(m); 1280 m = NULL; 1281 } 1282 } 1283 if (m == NULL) { 1284 error = ENOBUFS; 1285 goto out; 1286 } 1287 MCLAIM(m, &tcp_tx_mowner); 1288 m->m_data += max_linkhdr; 1289 m->m_len = hdrlen; 1290 } 1291 m->m_pkthdr.rcvif = (struct ifnet *)0; 1292 switch (af) { 1293 #ifdef INET 1294 case AF_INET: 1295 ip = mtod(m, struct ip *); 1296 #ifdef INET6 1297 ip6 = NULL; 1298 #endif 1299 th = (struct tcphdr *)(ip + 1); 1300 break; 1301 #endif 1302 #ifdef INET6 1303 case AF_INET6: 1304 ip = NULL; 1305 ip6 = mtod(m, struct ip6_hdr *); 1306 th = (struct tcphdr *)(ip6 + 1); 1307 break; 1308 #endif 1309 default: /*pacify gcc*/ 1310 ip = NULL; 1311 #ifdef INET6 1312 ip6 = NULL; 1313 #endif 1314 th = NULL; 1315 break; 1316 } 1317 if (tp->t_template == 0) 1318 panic("tcp_output"); 1319 if (tp->t_template->m_len < iphdrlen) 1320 panic("tcp_output"); 1321 bcopy(mtod(tp->t_template, void *), mtod(m, void *), iphdrlen); 1322 1323 /* 1324 * If we are starting a connection, send ECN setup 1325 * SYN packet. If we are on a retransmit, we may 1326 * resend those bits a number of times as per 1327 * RFC 3168. 1328 */ 1329 if (tp->t_state == TCPS_SYN_SENT && tcp_do_ecn) { 1330 if (tp->t_flags & TF_SYN_REXMT) { 1331 if (tp->t_ecn_retries--) 1332 flags |= TH_ECE|TH_CWR; 1333 } else { 1334 flags |= TH_ECE|TH_CWR; 1335 tp->t_ecn_retries = tcp_ecn_maxretries; 1336 } 1337 } 1338 1339 if (TCP_ECN_ALLOWED(tp)) { 1340 /* 1341 * If the peer has ECN, mark data packets 1342 * ECN capable. Ignore pure ack packets, retransmissions 1343 * and window probes. 1344 */ 1345 if (len > 0 && SEQ_GEQ(tp->snd_nxt, tp->snd_max) && 1346 !(tp->t_force && len == 1)) { 1347 switch (af) { 1348 #ifdef INET 1349 case AF_INET: 1350 tp->t_inpcb->inp_ip.ip_tos |= IPTOS_ECN_ECT0; 1351 break; 1352 #endif 1353 #ifdef INET6 1354 case AF_INET6: 1355 ip6->ip6_flow |= htonl(IPTOS_ECN_ECT0 << 20); 1356 break; 1357 #endif 1358 } 1359 tcpstat.tcps_ecn_ect++; 1360 } 1361 1362 /* 1363 * Reply with proper ECN notifications. 1364 */ 1365 if (tp->t_flags & TF_ECN_SND_CWR) { 1366 flags |= TH_CWR; 1367 tp->t_flags &= ~TF_ECN_SND_CWR; 1368 } 1369 if (tp->t_flags & TF_ECN_SND_ECE) { 1370 flags |= TH_ECE; 1371 } 1372 } 1373 1374 1375 /* 1376 * If we are doing retransmissions, then snd_nxt will 1377 * not reflect the first unsent octet. For ACK only 1378 * packets, we do not want the sequence number of the 1379 * retransmitted packet, we want the sequence number 1380 * of the next unsent octet. So, if there is no data 1381 * (and no SYN or FIN), use snd_max instead of snd_nxt 1382 * when filling in ti_seq. But if we are in persist 1383 * state, snd_max might reflect one byte beyond the 1384 * right edge of the window, so use snd_nxt in that 1385 * case, since we know we aren't doing a retransmission. 1386 * (retransmit and persist are mutually exclusive...) 1387 */ 1388 if (TCP_SACK_ENABLED(tp) && sack_rxmit) { 1389 th->th_seq = htonl(p->rxmit); 1390 p->rxmit += len; 1391 } else { 1392 if (len || (flags & (TH_SYN|TH_FIN)) || 1393 TCP_TIMER_ISARMED(tp, TCPT_PERSIST)) 1394 th->th_seq = htonl(tp->snd_nxt); 1395 else 1396 th->th_seq = htonl(tp->snd_max); 1397 } 1398 th->th_ack = htonl(tp->rcv_nxt); 1399 if (optlen) { 1400 bcopy((void *)opt, (void *)(th + 1), optlen); 1401 th->th_off = (sizeof (struct tcphdr) + optlen) >> 2; 1402 } 1403 th->th_flags = flags; 1404 /* 1405 * Calculate receive window. Don't shrink window, 1406 * but avoid silly window syndrome. 1407 */ 1408 if (win < (long)(so->so_rcv.sb_hiwat / 4) && win < (long)rxsegsize) 1409 win = 0; 1410 if (win > (long)TCP_MAXWIN << tp->rcv_scale) 1411 win = (long)TCP_MAXWIN << tp->rcv_scale; 1412 if (win < (long)(int32_t)(tp->rcv_adv - tp->rcv_nxt)) 1413 win = (long)(int32_t)(tp->rcv_adv - tp->rcv_nxt); 1414 th->th_win = htons((u_int16_t) (win>>tp->rcv_scale)); 1415 if (SEQ_GT(tp->snd_up, tp->snd_nxt)) { 1416 u_int32_t urp = tp->snd_up - tp->snd_nxt; 1417 if (urp > IP_MAXPACKET) 1418 urp = IP_MAXPACKET; 1419 th->th_urp = htons((u_int16_t)urp); 1420 th->th_flags |= TH_URG; 1421 } else 1422 /* 1423 * If no urgent pointer to send, then we pull 1424 * the urgent pointer to the left edge of the send window 1425 * so that it doesn't drift into the send window on sequence 1426 * number wraparound. 1427 */ 1428 tp->snd_up = tp->snd_una; /* drag it along */ 1429 1430 #ifdef TCP_SIGNATURE 1431 if (sigoff && (tp->t_flags & TF_SIGNATURE)) { 1432 struct secasvar *sav; 1433 u_int8_t *sigp; 1434 1435 sav = tcp_signature_getsav(m, th); 1436 1437 if (sav == NULL) { 1438 if (m) 1439 m_freem(m); 1440 return (EPERM); 1441 } 1442 1443 m->m_pkthdr.len = hdrlen + len; 1444 sigp = (char *)th + sizeof(*th) + sigoff; 1445 tcp_signature(m, th, (char *)th - mtod(m, char *), sav, sigp); 1446 1447 key_sa_recordxfer(sav, m); 1448 #ifdef FAST_IPSEC 1449 KEY_FREESAV(&sav); 1450 #else 1451 key_freesav(sav); 1452 #endif 1453 } 1454 #endif 1455 1456 /* 1457 * Set ourselves up to be checksummed just before the packet 1458 * hits the wire. 1459 */ 1460 switch (af) { 1461 #ifdef INET 1462 case AF_INET: 1463 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 1464 if (use_tso) { 1465 m->m_pkthdr.segsz = txsegsize; 1466 m->m_pkthdr.csum_flags = M_CSUM_TSOv4; 1467 } else { 1468 m->m_pkthdr.csum_flags = M_CSUM_TCPv4; 1469 if (len + optlen) { 1470 /* Fixup the pseudo-header checksum. */ 1471 /* XXXJRT Not IP Jumbogram safe. */ 1472 th->th_sum = in_cksum_addword(th->th_sum, 1473 htons((u_int16_t) (len + optlen))); 1474 } 1475 } 1476 break; 1477 #endif 1478 #ifdef INET6 1479 case AF_INET6: 1480 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 1481 if (use_tso) { 1482 m->m_pkthdr.segsz = txsegsize; 1483 m->m_pkthdr.csum_flags = M_CSUM_TSOv6; 1484 } else { 1485 m->m_pkthdr.csum_flags = M_CSUM_TCPv6; 1486 if (len + optlen) { 1487 /* Fixup the pseudo-header checksum. */ 1488 /* XXXJRT: Not IPv6 Jumbogram safe. */ 1489 th->th_sum = in_cksum_addword(th->th_sum, 1490 htons((u_int16_t) (len + optlen))); 1491 } 1492 } 1493 break; 1494 #endif 1495 } 1496 1497 /* 1498 * In transmit state, time the transmission and arrange for 1499 * the retransmit. In persist state, just set snd_max. 1500 */ 1501 if (tp->t_force == 0 || TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) { 1502 tcp_seq startseq = tp->snd_nxt; 1503 1504 /* 1505 * Advance snd_nxt over sequence space of this segment. 1506 * There are no states in which we send both a SYN and a FIN, 1507 * so we collapse the tests for these flags. 1508 */ 1509 if (flags & (TH_SYN|TH_FIN)) 1510 tp->snd_nxt++; 1511 if (sack_rxmit) 1512 goto timer; 1513 tp->snd_nxt += len; 1514 if (SEQ_GT(tp->snd_nxt, tp->snd_max)) { 1515 tp->snd_max = tp->snd_nxt; 1516 /* 1517 * Time this transmission if not a retransmission and 1518 * not currently timing anything. 1519 */ 1520 if (tp->t_rtttime == 0) { 1521 tp->t_rtttime = tcp_now; 1522 tp->t_rtseq = startseq; 1523 tcpstat.tcps_segstimed++; 1524 } 1525 } 1526 1527 /* 1528 * Set retransmit timer if not currently set, 1529 * and not doing an ack or a keep-alive probe. 1530 * Initial value for retransmit timer is smoothed 1531 * round-trip time + 2 * round-trip time variance. 1532 * Initialize shift counter which is used for backoff 1533 * of retransmit time. 1534 */ 1535 timer: 1536 if (TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 && 1537 ((sack_rxmit && tp->snd_nxt != tp->snd_max) || 1538 tp->snd_nxt != tp->snd_una)) { 1539 if (TCP_TIMER_ISARMED(tp, TCPT_PERSIST)) { 1540 TCP_TIMER_DISARM(tp, TCPT_PERSIST); 1541 tp->t_rxtshift = 0; 1542 } 1543 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 1544 } 1545 } else 1546 if (SEQ_GT(tp->snd_nxt + len, tp->snd_max)) 1547 tp->snd_max = tp->snd_nxt + len; 1548 1549 #ifdef TCP_DEBUG 1550 /* 1551 * Trace. 1552 */ 1553 if (so->so_options & SO_DEBUG) 1554 tcp_trace(TA_OUTPUT, tp->t_state, tp, m, 0); 1555 #endif 1556 1557 /* 1558 * Fill in IP length and desired time to live and 1559 * send to IP level. There should be a better way 1560 * to handle ttl and tos; we could keep them in 1561 * the template, but need a way to checksum without them. 1562 */ 1563 m->m_pkthdr.len = hdrlen + len; 1564 1565 switch (af) { 1566 #ifdef INET 1567 case AF_INET: 1568 ip->ip_len = htons(m->m_pkthdr.len); 1569 packetlen = m->m_pkthdr.len; 1570 if (tp->t_inpcb) { 1571 ip->ip_ttl = tp->t_inpcb->inp_ip.ip_ttl; 1572 ip->ip_tos = tp->t_inpcb->inp_ip.ip_tos; 1573 } 1574 #ifdef INET6 1575 else if (tp->t_in6pcb) { 1576 ip->ip_ttl = in6_selecthlim(tp->t_in6pcb, NULL); /*XXX*/ 1577 ip->ip_tos = 0; /*XXX*/ 1578 } 1579 #endif 1580 break; 1581 #endif 1582 #ifdef INET6 1583 case AF_INET6: 1584 packetlen = m->m_pkthdr.len; 1585 ip6->ip6_nxt = IPPROTO_TCP; 1586 if (tp->t_in6pcb) { 1587 /* 1588 * we separately set hoplimit for every segment, since 1589 * the user might want to change the value via 1590 * setsockopt. Also, desired default hop limit might 1591 * be changed via Neighbor Discovery. 1592 */ 1593 ip6->ip6_hlim = in6_selecthlim(tp->t_in6pcb, 1594 (rt = rtcache_validate(ro)) != NULL ? rt->rt_ifp 1595 : NULL); 1596 } 1597 /* ip6->ip6_flow = ??? */ 1598 /* ip6_plen will be filled in ip6_output(). */ 1599 break; 1600 #endif 1601 default: /*pacify gcc*/ 1602 packetlen = 0; 1603 break; 1604 } 1605 1606 switch (af) { 1607 #ifdef INET 1608 case AF_INET: 1609 { 1610 struct mbuf *opts; 1611 1612 if (tp->t_inpcb) 1613 opts = tp->t_inpcb->inp_options; 1614 else 1615 opts = NULL; 1616 error = ip_output(m, opts, ro, 1617 (tp->t_mtudisc ? IP_MTUDISC : 0) | 1618 (so->so_options & SO_DONTROUTE), 1619 (struct ip_moptions *)0, so); 1620 break; 1621 } 1622 #endif 1623 #ifdef INET6 1624 case AF_INET6: 1625 { 1626 struct ip6_pktopts *opts; 1627 1628 if (tp->t_in6pcb) 1629 opts = tp->t_in6pcb->in6p_outputopts; 1630 else 1631 opts = NULL; 1632 error = ip6_output(m, opts, ro, so->so_options & SO_DONTROUTE, 1633 NULL, so, NULL); 1634 break; 1635 } 1636 #endif 1637 default: 1638 error = EAFNOSUPPORT; 1639 break; 1640 } 1641 if (error) { 1642 out: 1643 if (error == ENOBUFS) { 1644 tcpstat.tcps_selfquench++; 1645 #ifdef INET 1646 if (tp->t_inpcb) 1647 tcp_quench(tp->t_inpcb, 0); 1648 #endif 1649 #ifdef INET6 1650 if (tp->t_in6pcb) 1651 tcp6_quench(tp->t_in6pcb, 0); 1652 #endif 1653 error = 0; 1654 } else if ((error == EHOSTUNREACH || error == ENETDOWN) && 1655 TCPS_HAVERCVDSYN(tp->t_state)) { 1656 tp->t_softerror = error; 1657 error = 0; 1658 } 1659 1660 /* Back out the seqence number advance. */ 1661 if (sack_rxmit) 1662 p->rxmit -= len; 1663 1664 /* Restart the delayed ACK timer, if necessary. */ 1665 if (tp->t_flags & TF_DELACK) 1666 TCP_RESTART_DELACK(tp); 1667 1668 return (error); 1669 } 1670 1671 if (packetlen > tp->t_pmtud_mtu_sent) 1672 tp->t_pmtud_mtu_sent = packetlen; 1673 1674 tcpstat.tcps_sndtotal++; 1675 if (tp->t_flags & TF_DELACK) 1676 tcpstat.tcps_delack++; 1677 1678 /* 1679 * Data sent (as far as we can tell). 1680 * If this advertises a larger window than any other segment, 1681 * then remember the size of the advertised window. 1682 * Any pending ACK has now been sent. 1683 */ 1684 if (win > 0 && SEQ_GT(tp->rcv_nxt+win, tp->rcv_adv)) 1685 tp->rcv_adv = tp->rcv_nxt + win; 1686 tp->last_ack_sent = tp->rcv_nxt; 1687 tp->t_flags &= ~TF_ACKNOW; 1688 TCP_CLEAR_DELACK(tp); 1689 #ifdef DIAGNOSTIC 1690 if (maxburst < 0) 1691 printf("tcp_output: maxburst exceeded by %d\n", -maxburst); 1692 #endif 1693 if (sendalot && (tp->t_congctl == &tcp_reno_ctl || --maxburst)) 1694 goto again; 1695 return (0); 1696 } 1697 1698 void 1699 tcp_setpersist(struct tcpcb *tp) 1700 { 1701 int t = ((tp->t_srtt >> 2) + tp->t_rttvar) >> (1 + 2); 1702 int nticks; 1703 1704 if (TCP_TIMER_ISARMED(tp, TCPT_REXMT)) 1705 panic("tcp_output REXMT"); 1706 /* 1707 * Start/restart persistance timer. 1708 */ 1709 if (t < tp->t_rttmin) 1710 t = tp->t_rttmin; 1711 TCPT_RANGESET(nticks, t * tcp_backoff[tp->t_rxtshift], 1712 TCPTV_PERSMIN, TCPTV_PERSMAX); 1713 TCP_TIMER_ARM(tp, TCPT_PERSIST, nticks); 1714 if (tp->t_rxtshift < TCP_MAXRXTSHIFT) 1715 tp->t_rxtshift++; 1716 } 1717
Indexes created Tue Sep 23 07:09:52 GMT 2025