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1 /* $NetBSD: tcp_output.c,v 1.153.2.2 2011/04/03 15:05:13 riz 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 1.153.2.2 2011/04/03 15:05:13 riz 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 #ifdef TCP_OUTPUT_COUNTERS 225 #include <sys/device.h> 226 227 extern struct evcnt tcp_output_bigheader; 228 extern struct evcnt tcp_output_predict_hit; 229 extern struct evcnt tcp_output_predict_miss; 230 extern struct evcnt tcp_output_copysmall; 231 extern struct evcnt tcp_output_copybig; 232 extern struct evcnt tcp_output_refbig; 233 234 #define TCP_OUTPUT_COUNTER_INCR(ev) (ev)->ev_count++ 235 #else 236 237 #define TCP_OUTPUT_COUNTER_INCR(ev) /* nothing */ 238 239 #endif /* TCP_OUTPUT_COUNTERS */ 240 241 static 242 #ifndef GPROF 243 inline 244 #endif 245 int 246 tcp_segsize(struct tcpcb *tp, int *txsegsizep, int *rxsegsizep, 247 boolean_t *alwaysfragp) 248 { 249 #ifdef INET 250 struct inpcb *inp = tp->t_inpcb; 251 #endif 252 #ifdef INET6 253 struct in6pcb *in6p = tp->t_in6pcb; 254 #endif 255 struct socket *so = NULL; 256 struct rtentry *rt; 257 struct ifnet *ifp; 258 int size; 259 int hdrlen; 260 int optlen; 261 262 *alwaysfragp = FALSE; 263 264 #ifdef DIAGNOSTIC 265 if (tp->t_inpcb && tp->t_in6pcb) 266 panic("tcp_segsize: both t_inpcb and t_in6pcb are set"); 267 #endif 268 switch (tp->t_family) { 269 #ifdef INET 270 case AF_INET: 271 hdrlen = sizeof(struct ip) + sizeof(struct tcphdr); 272 break; 273 #endif 274 #ifdef INET6 275 case AF_INET6: 276 hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 277 break; 278 #endif 279 default: 280 size = tcp_mssdflt; 281 goto out; 282 } 283 284 rt = NULL; 285 #ifdef INET 286 if (inp) { 287 rt = in_pcbrtentry(inp); 288 so = inp->inp_socket; 289 } 290 #endif 291 #ifdef INET6 292 if (in6p) { 293 rt = in6_pcbrtentry(in6p); 294 so = in6p->in6p_socket; 295 } 296 #endif 297 if (rt == NULL) { 298 size = tcp_mssdflt; 299 goto out; 300 } 301 302 ifp = rt->rt_ifp; 303 304 size = tcp_mssdflt; 305 if (tp->t_mtudisc && rt->rt_rmx.rmx_mtu != 0) { 306 #ifdef INET6 307 if (in6p && rt->rt_rmx.rmx_mtu < IPV6_MMTU) { 308 /* 309 * RFC2460 section 5, last paragraph: if path MTU is 310 * smaller than 1280, use 1280 as packet size and 311 * attach fragment header. 312 */ 313 size = IPV6_MMTU - hdrlen - sizeof(struct ip6_frag); 314 *alwaysfragp = TRUE; 315 } else 316 size = rt->rt_rmx.rmx_mtu - hdrlen; 317 #else 318 size = rt->rt_rmx.rmx_mtu - hdrlen; 319 #endif 320 } else if (ifp->if_flags & IFF_LOOPBACK) 321 size = ifp->if_mtu - hdrlen; 322 #ifdef INET 323 else if (inp && tp->t_mtudisc) 324 size = ifp->if_mtu - hdrlen; 325 else if (inp && in_localaddr(inp->inp_faddr)) 326 size = ifp->if_mtu - hdrlen; 327 #endif 328 #ifdef INET6 329 else if (in6p) { 330 #ifdef INET 331 if (IN6_IS_ADDR_V4MAPPED(&in6p->in6p_faddr)) { 332 /* mapped addr case */ 333 struct in_addr d; 334 bcopy(&in6p->in6p_faddr.s6_addr32[3], &d, sizeof(d)); 335 if (tp->t_mtudisc || in_localaddr(d)) 336 size = ifp->if_mtu - hdrlen; 337 } else 338 #endif 339 { 340 /* 341 * for IPv6, path MTU discovery is always turned on, 342 * or the node must use packet size <= 1280. 343 */ 344 size = tp->t_mtudisc ? IN6_LINKMTU(ifp) : IPV6_MMTU; 345 size -= hdrlen; 346 } 347 } 348 #endif 349 out: 350 /* 351 * Now we must make room for whatever extra TCP/IP options are in 352 * the packet. 353 */ 354 optlen = tcp_optlen(tp); 355 356 /* 357 * XXX tp->t_ourmss should have the right size, but without this code 358 * fragmentation will occur... need more investigation 359 */ 360 #ifdef INET 361 if (inp) { 362 #if defined(IPSEC) || defined(FAST_IPSEC) 363 if (! IPSEC_PCB_SKIP_IPSEC(inp->inp_sp, IPSEC_DIR_OUTBOUND)) 364 optlen += ipsec4_hdrsiz_tcp(tp); 365 #endif 366 optlen += ip_optlen(inp); 367 } 368 #endif 369 #ifdef INET6 370 #ifdef INET 371 if (in6p && tp->t_family == AF_INET) { 372 #if defined(IPSEC) || defined(FAST_IPSEC) 373 if (! IPSEC_PCB_SKIP_IPSEC(in6p->in6p_sp, IPSEC_DIR_OUTBOUND)) 374 optlen += ipsec4_hdrsiz_tcp(tp); 375 #endif 376 /* XXX size -= ip_optlen(in6p); */ 377 } else 378 #endif 379 if (in6p && tp->t_family == AF_INET6) { 380 #if defined(IPSEC) || defined(FAST_IPSEC) 381 if (! IPSEC_PCB_SKIP_IPSEC(in6p->in6p_sp, IPSEC_DIR_OUTBOUND)) 382 optlen += ipsec6_hdrsiz_tcp(tp); 383 #endif 384 optlen += ip6_optlen(in6p); 385 } 386 #endif 387 size -= optlen; 388 389 /* there may not be any room for data if mtu is too small */ 390 if (size < 0) 391 return (EMSGSIZE); 392 393 /* 394 * *rxsegsizep holds *estimated* inbound segment size (estimation 395 * assumes that path MTU is the same for both ways). this is only 396 * for silly window avoidance, do not use the value for other purposes. 397 * 398 * ipseclen is subtracted from both sides, this may not be right. 399 * I'm not quite sure about this (could someone comment). 400 */ 401 *txsegsizep = min(tp->t_peermss - optlen, size); 402 /* 403 * Never send more than half a buffer full. This insures that we can 404 * always keep 2 packets on the wire, no matter what SO_SNDBUF is, and 405 * therefore acks will never be delayed unless we run out of data to 406 * transmit. 407 */ 408 if (so) 409 *txsegsizep = min(so->so_snd.sb_hiwat >> 1, *txsegsizep); 410 *rxsegsizep = min(tp->t_ourmss - optlen, size); 411 412 if (*txsegsizep != tp->t_segsz) { 413 /* 414 * If the new segment size is larger, we don't want to 415 * mess up the congestion window, but if it is smaller 416 * we'll have to reduce the congestion window to ensure 417 * that we don't get into trouble with initial windows 418 * and the rest. In any case, if the segment size 419 * has changed, chances are the path has, too, and 420 * our congestion window will be different. 421 */ 422 if (*txsegsizep < tp->t_segsz) { 423 tp->snd_cwnd = max((tp->snd_cwnd / tp->t_segsz) 424 * *txsegsizep, *txsegsizep); 425 tp->snd_ssthresh = max((tp->snd_ssthresh / tp->t_segsz) 426 * *txsegsizep, *txsegsizep); 427 } 428 tp->t_segsz = *txsegsizep; 429 } 430 431 return (0); 432 } 433 434 static 435 #ifndef GPROF 436 inline 437 #endif 438 int 439 tcp_build_datapkt(struct tcpcb *tp, struct socket *so, int off, 440 long len, int hdrlen, struct mbuf **mp) 441 { 442 struct mbuf *m, *m0; 443 444 if (tp->t_force && len == 1) 445 tcpstat.tcps_sndprobe++; 446 else if (SEQ_LT(tp->snd_nxt, tp->snd_max)) { 447 tcpstat.tcps_sndrexmitpack++; 448 tcpstat.tcps_sndrexmitbyte += len; 449 } else { 450 tcpstat.tcps_sndpack++; 451 tcpstat.tcps_sndbyte += len; 452 } 453 #ifdef notyet 454 if ((m = m_copypack(so->so_snd.sb_mb, off, 455 (int)len, max_linkhdr + hdrlen)) == 0) 456 return (ENOBUFS); 457 /* 458 * m_copypack left space for our hdr; use it. 459 */ 460 m->m_len += hdrlen; 461 m->m_data -= hdrlen; 462 #else 463 MGETHDR(m, M_DONTWAIT, MT_HEADER); 464 if (__predict_false(m == NULL)) 465 return (ENOBUFS); 466 MCLAIM(m, &tcp_tx_mowner); 467 468 /* 469 * XXX Because other code assumes headers will fit in 470 * XXX one header mbuf. 471 * 472 * (This code should almost *never* be run.) 473 */ 474 if (__predict_false((max_linkhdr + hdrlen) > MHLEN)) { 475 TCP_OUTPUT_COUNTER_INCR(&tcp_output_bigheader); 476 MCLGET(m, M_DONTWAIT); 477 if ((m->m_flags & M_EXT) == 0) { 478 m_freem(m); 479 return (ENOBUFS); 480 } 481 } 482 483 m->m_data += max_linkhdr; 484 m->m_len = hdrlen; 485 486 /* 487 * To avoid traversing the whole sb_mb chain for correct 488 * data to send, remember last sent mbuf, its offset and 489 * the sent size. When called the next time, see if the 490 * data to send is directly following the previous transfer. 491 * This is important for large TCP windows. 492 */ 493 if (off == 0 || tp->t_lastm == NULL || 494 (tp->t_lastoff + tp->t_lastlen) != off) { 495 TCP_OUTPUT_COUNTER_INCR(&tcp_output_predict_miss); 496 /* 497 * Either a new packet or a retransmit. 498 * Start from the beginning. 499 */ 500 tp->t_lastm = so->so_snd.sb_mb; 501 tp->t_inoff = off; 502 } else { 503 TCP_OUTPUT_COUNTER_INCR(&tcp_output_predict_hit); 504 tp->t_inoff += tp->t_lastlen; 505 } 506 507 /* Traverse forward to next packet */ 508 while (tp->t_inoff > 0) { 509 if (tp->t_lastm == NULL) 510 panic("tp->t_lastm == NULL"); 511 if (tp->t_inoff < tp->t_lastm->m_len) 512 break; 513 tp->t_inoff -= tp->t_lastm->m_len; 514 tp->t_lastm = tp->t_lastm->m_next; 515 } 516 517 tp->t_lastoff = off; 518 tp->t_lastlen = len; 519 m0 = tp->t_lastm; 520 off = tp->t_inoff; 521 522 if (len <= M_TRAILINGSPACE(m)) { 523 m_copydata(m0, off, (int) len, mtod(m, caddr_t) + hdrlen); 524 m->m_len += len; 525 TCP_OUTPUT_COUNTER_INCR(&tcp_output_copysmall); 526 } else { 527 m->m_next = m_copy(m0, off, (int) len); 528 if (m->m_next == NULL) { 529 m_freem(m); 530 return (ENOBUFS); 531 } 532 #ifdef TCP_OUTPUT_COUNTERS 533 if (m->m_next->m_flags & M_EXT) 534 TCP_OUTPUT_COUNTER_INCR(&tcp_output_refbig); 535 else 536 TCP_OUTPUT_COUNTER_INCR(&tcp_output_copybig); 537 #endif /* TCP_OUTPUT_COUNTERS */ 538 } 539 #endif 540 541 *mp = m; 542 return (0); 543 } 544 545 /* 546 * Tcp output routine: figure out what should be sent and send it. 547 */ 548 int 549 tcp_output(struct tcpcb *tp) 550 { 551 struct socket *so; 552 struct route *ro; 553 long len, win; 554 int off, flags, error; 555 struct mbuf *m; 556 struct ip *ip; 557 #ifdef INET6 558 struct ip6_hdr *ip6; 559 #endif 560 struct tcphdr *th; 561 u_char opt[MAX_TCPOPTLEN]; 562 unsigned optlen, hdrlen, packetlen; 563 unsigned int sack_numblks; 564 int idle, sendalot, txsegsize, rxsegsize; 565 int txsegsize_nosack; 566 int maxburst = TCP_MAXBURST; 567 int af; /* address family on the wire */ 568 int iphdrlen; 569 int has_tso4, has_tso6; 570 int has_tso, use_tso; 571 boolean_t alwaysfrag; 572 int sack_rxmit; 573 int sack_bytes_rxmt; 574 int ecn_tos; 575 struct sackhole *p; 576 #ifdef TCP_SIGNATURE 577 int sigoff = 0; 578 #endif 579 580 #ifdef DIAGNOSTIC 581 if (tp->t_inpcb && tp->t_in6pcb) 582 panic("tcp_output: both t_inpcb and t_in6pcb are set"); 583 #endif 584 so = NULL; 585 ro = NULL; 586 if (tp->t_inpcb) { 587 so = tp->t_inpcb->inp_socket; 588 ro = &tp->t_inpcb->inp_route; 589 } 590 #ifdef INET6 591 else if (tp->t_in6pcb) { 592 so = tp->t_in6pcb->in6p_socket; 593 ro = (struct route *)&tp->t_in6pcb->in6p_route; 594 } 595 #endif 596 597 switch (af = tp->t_family) { 598 #ifdef INET 599 case AF_INET: 600 if (tp->t_inpcb) 601 break; 602 #ifdef INET6 603 /* mapped addr case */ 604 if (tp->t_in6pcb) 605 break; 606 #endif 607 return (EINVAL); 608 #endif 609 #ifdef INET6 610 case AF_INET6: 611 if (tp->t_in6pcb) 612 break; 613 return (EINVAL); 614 #endif 615 default: 616 return (EAFNOSUPPORT); 617 } 618 619 if (tcp_segsize(tp, &txsegsize, &rxsegsize, &alwaysfrag)) 620 return (EMSGSIZE); 621 622 idle = (tp->snd_max == tp->snd_una); 623 624 /* 625 * Determine if we can use TCP segmentation offload: 626 * - If we're using IPv4 627 * - If there is not an IPsec policy that prevents it 628 * - If the interface can do it 629 */ 630 has_tso4 = has_tso6 = FALSE; 631 #if defined(INET) 632 has_tso4 = tp->t_inpcb != NULL && 633 #if defined(IPSEC) || defined(FAST_IPSEC) 634 IPSEC_PCB_SKIP_IPSEC(tp->t_inpcb->inp_sp, 635 IPSEC_DIR_OUTBOUND) && 636 #endif 637 tp->t_inpcb->inp_route.ro_rt != NULL && 638 (tp->t_inpcb->inp_route.ro_rt->rt_ifp->if_capenable & 639 IFCAP_TSOv4) != 0; 640 #endif /* defined(INET) */ 641 #if defined(INET6) 642 has_tso6 = tp->t_in6pcb != NULL && 643 #if defined(IPSEC) || defined(FAST_IPSEC) 644 IPSEC_PCB_SKIP_IPSEC(tp->t_in6pcb->in6p_sp, 645 IPSEC_DIR_OUTBOUND) && 646 #endif 647 tp->t_in6pcb->in6p_route.ro_rt != NULL && 648 (tp->t_in6pcb->in6p_route.ro_rt->rt_ifp->if_capenable & 649 IFCAP_TSOv6) != 0; 650 #endif /* defined(INET6) */ 651 has_tso = (has_tso4 || has_tso6) && !alwaysfrag; 652 653 /* 654 * Restart Window computation. From draft-floyd-incr-init-win-03: 655 * 656 * Optionally, a TCP MAY set the restart window to the 657 * minimum of the value used for the initial window and 658 * the current value of cwnd (in other words, using a 659 * larger value for the restart window should never increase 660 * the size of cwnd). 661 */ 662 if (tcp_cwm) { 663 /* 664 * Hughes/Touch/Heidemann Congestion Window Monitoring. 665 * Count the number of packets currently pending 666 * acknowledgement, and limit our congestion window 667 * to a pre-determined allowed burst size plus that count. 668 * This prevents bursting once all pending packets have 669 * been acknowledged (i.e. transmission is idle). 670 * 671 * XXX Link this to Initial Window? 672 */ 673 tp->snd_cwnd = min(tp->snd_cwnd, 674 (tcp_cwm_burstsize * txsegsize) + 675 (tp->snd_nxt - tp->snd_una)); 676 } else { 677 if (idle && (tcp_now - tp->t_rcvtime) >= tp->t_rxtcur) { 678 /* 679 * We have been idle for "a while" and no acks are 680 * expected to clock out any data we send -- 681 * slow start to get ack "clock" running again. 682 */ 683 int ss = tcp_init_win; 684 #ifdef INET 685 if (tp->t_inpcb && 686 in_localaddr(tp->t_inpcb->inp_faddr)) 687 ss = tcp_init_win_local; 688 #endif 689 #ifdef INET6 690 if (tp->t_in6pcb && 691 in6_localaddr(&tp->t_in6pcb->in6p_faddr)) 692 ss = tcp_init_win_local; 693 #endif 694 tp->snd_cwnd = min(tp->snd_cwnd, 695 TCP_INITIAL_WINDOW(ss, txsegsize)); 696 } 697 } 698 699 txsegsize_nosack = txsegsize; 700 again: 701 ecn_tos = 0; 702 use_tso = has_tso; 703 if ((tp->t_flags & (TF_ECN_SND_CWR|TF_ECN_SND_ECE)) != 0) { 704 /* don't duplicate CWR/ECE. */ 705 use_tso = 0; 706 } 707 TCP_REASS_LOCK(tp); 708 sack_numblks = tcp_sack_numblks(tp); 709 if (sack_numblks) { 710 int sackoptlen; 711 712 sackoptlen = TCP_SACK_OPTLEN(sack_numblks); 713 if (sackoptlen > txsegsize_nosack) { 714 sack_numblks = 0; /* give up SACK */ 715 txsegsize = txsegsize_nosack; 716 } else { 717 if ((tp->rcv_sack_flags & TCPSACK_HAVED) != 0) { 718 /* don't duplicate D-SACK. */ 719 use_tso = 0; 720 } 721 txsegsize = txsegsize_nosack - sackoptlen; 722 } 723 } else { 724 txsegsize = txsegsize_nosack; 725 } 726 727 /* 728 * Determine length of data that should be transmitted, and 729 * flags that should be used. If there is some data or critical 730 * controls (SYN, RST) to send, then transmit; otherwise, 731 * investigate further. 732 * 733 * Readjust SACK information to avoid resending duplicate data. 734 */ 735 if (TCP_SACK_ENABLED(tp) && SEQ_LT(tp->snd_nxt, tp->snd_max)) 736 tcp_sack_adjust(tp); 737 sendalot = 0; 738 off = tp->snd_nxt - tp->snd_una; 739 win = min(tp->snd_wnd, tp->snd_cwnd); 740 741 flags = tcp_outflags[tp->t_state]; 742 743 /* 744 * Send any SACK-generated retransmissions. If we're explicitly trying 745 * to send out new data (when sendalot is 1), bypass this function. 746 * If we retransmit in fast recovery mode, decrement snd_cwnd, since 747 * we're replacing a (future) new transmission with a retransmission 748 * now, and we previously incremented snd_cwnd in tcp_input(). 749 */ 750 /* 751 * Still in sack recovery , reset rxmit flag to zero. 752 */ 753 sack_rxmit = 0; 754 sack_bytes_rxmt = 0; 755 len = 0; 756 p = NULL; 757 do { 758 long cwin; 759 if (!TCP_SACK_ENABLED(tp)) 760 break; 761 if (tp->t_partialacks < 0) 762 break; 763 p = tcp_sack_output(tp, &sack_bytes_rxmt); 764 if (p == NULL) 765 break; 766 767 cwin = min(tp->snd_wnd, tp->snd_cwnd) - sack_bytes_rxmt; 768 if (cwin < 0) 769 cwin = 0; 770 /* Do not retransmit SACK segments beyond snd_recover */ 771 if (SEQ_GT(p->end, tp->snd_recover)) { 772 /* 773 * (At least) part of sack hole extends beyond 774 * snd_recover. Check to see if we can rexmit data 775 * for this hole. 776 */ 777 if (SEQ_GEQ(p->rxmit, tp->snd_recover)) { 778 /* 779 * Can't rexmit any more data for this hole. 780 * That data will be rexmitted in the next 781 * sack recovery episode, when snd_recover 782 * moves past p->rxmit. 783 */ 784 p = NULL; 785 break; 786 } 787 /* Can rexmit part of the current hole */ 788 len = ((long)ulmin(cwin, tp->snd_recover - p->rxmit)); 789 } else 790 len = ((long)ulmin(cwin, p->end - p->rxmit)); 791 off = p->rxmit - tp->snd_una; 792 if (off + len > so->so_snd.sb_cc) { 793 /* 1 for TH_FIN */ 794 KASSERT(off + len == so->so_snd.sb_cc + 1); 795 KASSERT(p->rxmit + len == tp->snd_max); 796 len = so->so_snd.sb_cc - off; 797 } 798 if (len > 0) { 799 sack_rxmit = 1; 800 sendalot = 1; 801 } 802 } while (/*CONSTCOND*/0); 803 804 /* 805 * If in persist timeout with window of 0, send 1 byte. 806 * Otherwise, if window is small but nonzero 807 * and timer expired, we will send what we can 808 * and go to transmit state. 809 */ 810 if (tp->t_force) { 811 if (win == 0) { 812 /* 813 * If we still have some data to send, then 814 * clear the FIN bit. Usually this would 815 * happen below when it realizes that we 816 * aren't sending all the data. However, 817 * if we have exactly 1 byte of unset data, 818 * then it won't clear the FIN bit below, 819 * and if we are in persist state, we wind 820 * up sending the packet without recording 821 * that we sent the FIN bit. 822 * 823 * We can't just blindly clear the FIN bit, 824 * because if we don't have any more data 825 * to send then the probe will be the FIN 826 * itself. 827 */ 828 if (off < so->so_snd.sb_cc) 829 flags &= ~TH_FIN; 830 win = 1; 831 } else { 832 TCP_TIMER_DISARM(tp, TCPT_PERSIST); 833 tp->t_rxtshift = 0; 834 } 835 } 836 837 if (sack_rxmit == 0) { 838 if (TCP_SACK_ENABLED(tp) && tp->t_partialacks >= 0) { 839 long cwin; 840 841 /* 842 * We are inside of a SACK recovery episode and are 843 * sending new data, having retransmitted all the 844 * data possible in the scoreboard. 845 */ 846 if (tp->snd_wnd < so->so_snd.sb_cc) { 847 len = tp->snd_wnd - off; 848 flags &= ~TH_FIN; 849 } else { 850 len = so->so_snd.sb_cc - off; 851 } 852 853 /* 854 * From FreeBSD: 855 * Don't remove this (len > 0) check ! 856 * We explicitly check for len > 0 here (although it 857 * isn't really necessary), to work around a gcc 858 * optimization issue - to force gcc to compute 859 * len above. Without this check, the computation 860 * of len is bungled by the optimizer. 861 */ 862 if (len > 0) { 863 cwin = tp->snd_cwnd - 864 (tp->snd_nxt - tp->sack_newdata) - 865 sack_bytes_rxmt; 866 if (cwin < 0) 867 cwin = 0; 868 if (cwin < len) { 869 len = cwin; 870 flags &= ~TH_FIN; 871 } 872 } 873 } else if (win < so->so_snd.sb_cc) { 874 len = win - off; 875 flags &= ~TH_FIN; 876 } else { 877 len = so->so_snd.sb_cc - off; 878 } 879 } 880 881 if (len < 0) { 882 /* 883 * If FIN has been sent but not acked, 884 * but we haven't been called to retransmit, 885 * len will be -1. Otherwise, window shrank 886 * after we sent into it. If window shrank to 0, 887 * cancel pending retransmit, pull snd_nxt back 888 * to (closed) window, and set the persist timer 889 * if it isn't already going. If the window didn't 890 * close completely, just wait for an ACK. 891 * 892 * If we have a pending FIN, either it has already been 893 * transmitted or it is outside the window, so drop it. 894 * If the FIN has been transmitted, but this is not a 895 * retransmission, then len must be -1. Therefore we also 896 * prevent here the sending of `gratuitous FINs'. This 897 * eliminates the need to check for that case below (e.g. 898 * to back up snd_nxt before the FIN so that the sequence 899 * number is correct). 900 */ 901 len = 0; 902 flags &= ~TH_FIN; 903 if (win == 0) { 904 TCP_TIMER_DISARM(tp, TCPT_REXMT); 905 tp->t_rxtshift = 0; 906 tp->snd_nxt = tp->snd_una; 907 if (TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) 908 tcp_setpersist(tp); 909 } 910 } 911 if (len > txsegsize) { 912 if (use_tso) { 913 /* 914 * Truncate TSO transfers to IP_MAXPACKET, and make 915 * sure that we send equal size transfers down the 916 * stack (rather than big-small-big-small-...). 917 */ 918 #ifdef INET6 919 #if IPV6_MAXPACKET != IP_MAXPACKET 920 #error IPV6_MAXPACKET != IP_MAXPACKET 921 #endif 922 #endif 923 len = (min(len, IP_MAXPACKET) / txsegsize) * txsegsize; 924 if (len <= txsegsize) { 925 use_tso = 0; 926 } 927 } else 928 len = txsegsize; 929 flags &= ~TH_FIN; 930 sendalot = 1; 931 } else 932 use_tso = 0; 933 if (sack_rxmit) { 934 if (SEQ_LT(p->rxmit + len, tp->snd_una + so->so_snd.sb_cc)) 935 flags &= ~TH_FIN; 936 } 937 938 win = sbspace(&so->so_rcv); 939 940 /* 941 * Sender silly window avoidance. If connection is idle 942 * and can send all data, a maximum segment, 943 * at least a maximum default-size segment do it, 944 * or are forced, do it; otherwise don't bother. 945 * If peer's buffer is tiny, then send 946 * when window is at least half open. 947 * If retransmitting (possibly after persist timer forced us 948 * to send into a small window), then must resend. 949 */ 950 if (len) { 951 if (len >= txsegsize) 952 goto send; 953 if ((so->so_state & SS_MORETOCOME) == 0 && 954 ((idle || tp->t_flags & TF_NODELAY) && 955 len + off >= so->so_snd.sb_cc)) 956 goto send; 957 if (tp->t_force) 958 goto send; 959 if (len >= tp->max_sndwnd / 2) 960 goto send; 961 if (SEQ_LT(tp->snd_nxt, tp->snd_max)) 962 goto send; 963 if (sack_rxmit) 964 goto send; 965 } 966 967 /* 968 * Compare available window to amount of window known to peer 969 * (as advertised window less next expected input). If the 970 * difference is at least twice the size of the largest segment 971 * we expect to receive (i.e. two segments) or at least 50% of 972 * the maximum possible window, then want to send a window update 973 * to peer. 974 */ 975 if (win > 0) { 976 /* 977 * "adv" is the amount we can increase the window, 978 * taking into account that we are limited by 979 * TCP_MAXWIN << tp->rcv_scale. 980 */ 981 long adv = min(win, (long)TCP_MAXWIN << tp->rcv_scale) - 982 (tp->rcv_adv - tp->rcv_nxt); 983 984 if (adv >= (long) (2 * rxsegsize)) 985 goto send; 986 if (2 * adv >= (long) so->so_rcv.sb_hiwat) 987 goto send; 988 } 989 990 /* 991 * Send if we owe peer an ACK. 992 */ 993 if (tp->t_flags & TF_ACKNOW) 994 goto send; 995 if (flags & (TH_SYN|TH_FIN|TH_RST)) 996 goto send; 997 if (SEQ_GT(tp->snd_up, tp->snd_una)) 998 goto send; 999 /* 1000 * In SACK, it is possible for tcp_output to fail to send a segment 1001 * after the retransmission timer has been turned off. Make sure 1002 * that the retransmission timer is set. 1003 */ 1004 if (TCP_SACK_ENABLED(tp) && SEQ_GT(tp->snd_max, tp->snd_una) && 1005 !TCP_TIMER_ISARMED(tp, TCPT_REXMT) && 1006 !TCP_TIMER_ISARMED(tp, TCPT_PERSIST)) { 1007 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 1008 goto just_return; 1009 } 1010 1011 /* 1012 * TCP window updates are not reliable, rather a polling protocol 1013 * using ``persist'' packets is used to insure receipt of window 1014 * updates. The three ``states'' for the output side are: 1015 * idle not doing retransmits or persists 1016 * persisting to move a small or zero window 1017 * (re)transmitting and thereby not persisting 1018 * 1019 * tp->t_timer[TCPT_PERSIST] 1020 * is set when we are in persist state. 1021 * tp->t_force 1022 * is set when we are called to send a persist packet. 1023 * tp->t_timer[TCPT_REXMT] 1024 * is set when we are retransmitting 1025 * The output side is idle when both timers are zero. 1026 * 1027 * If send window is too small, there is data to transmit, and no 1028 * retransmit or persist is pending, then go to persist state. 1029 * If nothing happens soon, send when timer expires: 1030 * if window is nonzero, transmit what we can, 1031 * otherwise force out a byte. 1032 */ 1033 if (so->so_snd.sb_cc && TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 && 1034 TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) { 1035 tp->t_rxtshift = 0; 1036 tcp_setpersist(tp); 1037 } 1038 1039 /* 1040 * No reason to send a segment, just return. 1041 */ 1042 just_return: 1043 TCP_REASS_UNLOCK(tp); 1044 return (0); 1045 1046 send: 1047 /* 1048 * Before ESTABLISHED, force sending of initial options 1049 * unless TCP set not to do any options. 1050 * NOTE: we assume that the IP/TCP header plus TCP options 1051 * always fit in a single mbuf, leaving room for a maximum 1052 * link header, i.e. 1053 * max_linkhdr + sizeof (struct tcpiphdr) + optlen <= MCLBYTES 1054 */ 1055 optlen = 0; 1056 switch (af) { 1057 #ifdef INET 1058 case AF_INET: 1059 iphdrlen = sizeof(struct ip) + sizeof(struct tcphdr); 1060 break; 1061 #endif 1062 #ifdef INET6 1063 case AF_INET6: 1064 iphdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 1065 break; 1066 #endif 1067 default: /*pacify gcc*/ 1068 iphdrlen = 0; 1069 break; 1070 } 1071 hdrlen = iphdrlen; 1072 if (flags & TH_SYN) { 1073 struct rtentry *rt; 1074 1075 rt = NULL; 1076 #ifdef INET 1077 if (tp->t_inpcb) 1078 rt = in_pcbrtentry(tp->t_inpcb); 1079 #endif 1080 #ifdef INET6 1081 if (tp->t_in6pcb) 1082 rt = in6_pcbrtentry(tp->t_in6pcb); 1083 #endif 1084 1085 tp->snd_nxt = tp->iss; 1086 tp->t_ourmss = tcp_mss_to_advertise(rt != NULL ? 1087 rt->rt_ifp : NULL, af); 1088 if ((tp->t_flags & TF_NOOPT) == 0) { 1089 opt[0] = TCPOPT_MAXSEG; 1090 opt[1] = 4; 1091 opt[2] = (tp->t_ourmss >> 8) & 0xff; 1092 opt[3] = tp->t_ourmss & 0xff; 1093 optlen = 4; 1094 1095 if ((tp->t_flags & TF_REQ_SCALE) && 1096 ((flags & TH_ACK) == 0 || 1097 (tp->t_flags & TF_RCVD_SCALE))) { 1098 *((u_int32_t *) (opt + optlen)) = htonl( 1099 TCPOPT_NOP << 24 | 1100 TCPOPT_WINDOW << 16 | 1101 TCPOLEN_WINDOW << 8 | 1102 tp->request_r_scale); 1103 optlen += 4; 1104 } 1105 if (tcp_do_sack) { 1106 u_int8_t *cp = (u_int8_t *)(opt + optlen); 1107 1108 cp[0] = TCPOPT_SACK_PERMITTED; 1109 cp[1] = 2; 1110 cp[2] = TCPOPT_NOP; 1111 cp[3] = TCPOPT_NOP; 1112 optlen += 4; 1113 } 1114 } 1115 } 1116 1117 /* 1118 * Send a timestamp and echo-reply if this is a SYN and our side 1119 * wants to use timestamps (TF_REQ_TSTMP is set) or both our side 1120 * and our peer have sent timestamps in our SYN's. 1121 */ 1122 if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP && 1123 (flags & TH_RST) == 0 && 1124 ((flags & (TH_SYN|TH_ACK)) == TH_SYN || 1125 (tp->t_flags & TF_RCVD_TSTMP))) { 1126 u_int32_t *lp = (u_int32_t *)(opt + optlen); 1127 1128 /* Form timestamp option as shown in appendix A of RFC 1323. */ 1129 *lp++ = htonl(TCPOPT_TSTAMP_HDR); 1130 *lp++ = htonl(TCP_TIMESTAMP(tp)); 1131 *lp = htonl(tp->ts_recent); 1132 optlen += TCPOLEN_TSTAMP_APPA; 1133 } 1134 1135 /* 1136 * Tack on the SACK block if it is necessary. 1137 */ 1138 if (sack_numblks) { 1139 int sack_len; 1140 u_char *bp = (u_char *)(opt + optlen); 1141 u_int32_t *lp = (u_int32_t *)(bp + 4); 1142 struct ipqent *tiqe; 1143 1144 sack_len = sack_numblks * 8 + 2; 1145 bp[0] = TCPOPT_NOP; 1146 bp[1] = TCPOPT_NOP; 1147 bp[2] = TCPOPT_SACK; 1148 bp[3] = sack_len; 1149 if ((tp->rcv_sack_flags & TCPSACK_HAVED) != 0) { 1150 sack_numblks--; 1151 *lp++ = htonl(tp->rcv_dsack_block.left); 1152 *lp++ = htonl(tp->rcv_dsack_block.right); 1153 tp->rcv_sack_flags &= ~TCPSACK_HAVED; 1154 } 1155 for (tiqe = TAILQ_FIRST(&tp->timeq); 1156 sack_numblks > 0; tiqe = TAILQ_NEXT(tiqe, ipqe_timeq)) { 1157 KASSERT(tiqe != NULL); 1158 sack_numblks--; 1159 *lp++ = htonl(tiqe->ipqe_seq); 1160 *lp++ = htonl(tiqe->ipqe_seq + tiqe->ipqe_len + 1161 ((tiqe->ipqe_flags & TH_FIN) != 0 ? 1 : 0)); 1162 } 1163 optlen += sack_len + 2; 1164 } 1165 TCP_REASS_UNLOCK(tp); 1166 1167 #ifdef TCP_SIGNATURE 1168 if (tp->t_flags & TF_SIGNATURE) { 1169 u_char *bp; 1170 /* 1171 * Initialize TCP-MD5 option (RFC2385) 1172 */ 1173 bp = (u_char *)opt + optlen; 1174 *bp++ = TCPOPT_SIGNATURE; 1175 *bp++ = TCPOLEN_SIGNATURE; 1176 sigoff = optlen + 2; 1177 bzero(bp, TCP_SIGLEN); 1178 bp += TCP_SIGLEN; 1179 optlen += TCPOLEN_SIGNATURE; 1180 /* 1181 * Terminate options list and maintain 32-bit alignment. 1182 */ 1183 *bp++ = TCPOPT_NOP; 1184 *bp++ = TCPOPT_EOL; 1185 optlen += 2; 1186 } 1187 #endif /* TCP_SIGNATURE */ 1188 1189 hdrlen += optlen; 1190 1191 #ifdef DIAGNOSTIC 1192 if (!use_tso && len > txsegsize) 1193 panic("tcp data to be sent is larger than segment"); 1194 else if (use_tso && len > IP_MAXPACKET) 1195 panic("tcp data to be sent is larger than max TSO size"); 1196 if (max_linkhdr + hdrlen > MCLBYTES) 1197 panic("tcphdr too big"); 1198 #endif 1199 1200 /* 1201 * Grab a header mbuf, attaching a copy of data to 1202 * be transmitted, and initialize the header from 1203 * the template for sends on this connection. 1204 */ 1205 if (len) { 1206 error = tcp_build_datapkt(tp, so, off, len, hdrlen, &m); 1207 if (error) 1208 goto out; 1209 /* 1210 * If we're sending everything we've got, set PUSH. 1211 * (This will keep happy those implementations which only 1212 * give data to the user when a buffer fills or 1213 * a PUSH comes in.) 1214 */ 1215 if (off + len == so->so_snd.sb_cc) 1216 flags |= TH_PUSH; 1217 } else { 1218 if (tp->t_flags & TF_ACKNOW) 1219 tcpstat.tcps_sndacks++; 1220 else if (flags & (TH_SYN|TH_FIN|TH_RST)) 1221 tcpstat.tcps_sndctrl++; 1222 else if (SEQ_GT(tp->snd_up, tp->snd_una)) 1223 tcpstat.tcps_sndurg++; 1224 else 1225 tcpstat.tcps_sndwinup++; 1226 1227 MGETHDR(m, M_DONTWAIT, MT_HEADER); 1228 if (m != NULL && max_linkhdr + hdrlen > MHLEN) { 1229 MCLGET(m, M_DONTWAIT); 1230 if ((m->m_flags & M_EXT) == 0) { 1231 m_freem(m); 1232 m = NULL; 1233 } 1234 } 1235 if (m == NULL) { 1236 error = ENOBUFS; 1237 goto out; 1238 } 1239 MCLAIM(m, &tcp_tx_mowner); 1240 m->m_data += max_linkhdr; 1241 m->m_len = hdrlen; 1242 } 1243 m->m_pkthdr.rcvif = (struct ifnet *)0; 1244 switch (af) { 1245 #ifdef INET 1246 case AF_INET: 1247 ip = mtod(m, struct ip *); 1248 #ifdef INET6 1249 ip6 = NULL; 1250 #endif 1251 th = (struct tcphdr *)(ip + 1); 1252 break; 1253 #endif 1254 #ifdef INET6 1255 case AF_INET6: 1256 ip = NULL; 1257 ip6 = mtod(m, struct ip6_hdr *); 1258 th = (struct tcphdr *)(ip6 + 1); 1259 break; 1260 #endif 1261 default: /*pacify gcc*/ 1262 ip = NULL; 1263 #ifdef INET6 1264 ip6 = NULL; 1265 #endif 1266 th = NULL; 1267 break; 1268 } 1269 if (tp->t_template == 0) 1270 panic("tcp_output"); 1271 if (tp->t_template->m_len < iphdrlen) 1272 panic("tcp_output"); 1273 bcopy(mtod(tp->t_template, caddr_t), mtod(m, caddr_t), iphdrlen); 1274 1275 /* 1276 * If we are starting a connection, send ECN setup 1277 * SYN packet. If we are on a retransmit, we may 1278 * resend those bits a number of times as per 1279 * RFC 3168. 1280 */ 1281 if (tp->t_state == TCPS_SYN_SENT && tcp_do_ecn) { 1282 if (tp->t_flags & TF_SYN_REXMT) { 1283 if (tp->t_ecn_retries--) 1284 flags |= TH_ECE|TH_CWR; 1285 } else { 1286 flags |= TH_ECE|TH_CWR; 1287 tp->t_ecn_retries = tcp_ecn_maxretries; 1288 } 1289 } 1290 1291 if (TCP_ECN_ALLOWED(tp)) { 1292 /* 1293 * If the peer has ECN, mark data packets 1294 * ECN capable. Ignore pure ack packets, retransmissions 1295 * and window probes. 1296 */ 1297 if (len > 0 && SEQ_GEQ(tp->snd_nxt, tp->snd_max) && 1298 !(tp->t_force && len == 1)) { 1299 ecn_tos = IPTOS_ECN_ECT0; 1300 tcpstat.tcps_ecn_ect++; 1301 } 1302 1303 /* 1304 * Reply with proper ECN notifications. 1305 */ 1306 if (tp->t_flags & TF_ECN_SND_CWR) { 1307 flags |= TH_CWR; 1308 tp->t_flags &= ~TF_ECN_SND_CWR; 1309 } 1310 if (tp->t_flags & TF_ECN_SND_ECE) { 1311 flags |= TH_ECE; 1312 } 1313 } 1314 1315 1316 /* 1317 * If we are doing retransmissions, then snd_nxt will 1318 * not reflect the first unsent octet. For ACK only 1319 * packets, we do not want the sequence number of the 1320 * retransmitted packet, we want the sequence number 1321 * of the next unsent octet. So, if there is no data 1322 * (and no SYN or FIN), use snd_max instead of snd_nxt 1323 * when filling in ti_seq. But if we are in persist 1324 * state, snd_max might reflect one byte beyond the 1325 * right edge of the window, so use snd_nxt in that 1326 * case, since we know we aren't doing a retransmission. 1327 * (retransmit and persist are mutually exclusive...) 1328 */ 1329 if (TCP_SACK_ENABLED(tp) && sack_rxmit) { 1330 th->th_seq = htonl(p->rxmit); 1331 p->rxmit += len; 1332 } else { 1333 if (len || (flags & (TH_SYN|TH_FIN)) || 1334 TCP_TIMER_ISARMED(tp, TCPT_PERSIST)) 1335 th->th_seq = htonl(tp->snd_nxt); 1336 else 1337 th->th_seq = htonl(tp->snd_max); 1338 } 1339 th->th_ack = htonl(tp->rcv_nxt); 1340 if (optlen) { 1341 bcopy((caddr_t)opt, (caddr_t)(th + 1), optlen); 1342 th->th_off = (sizeof (struct tcphdr) + optlen) >> 2; 1343 } 1344 th->th_flags = flags; 1345 /* 1346 * Calculate receive window. Don't shrink window, 1347 * but avoid silly window syndrome. 1348 */ 1349 if (win < (long)(so->so_rcv.sb_hiwat / 4) && win < (long)rxsegsize) 1350 win = 0; 1351 if (win > (long)TCP_MAXWIN << tp->rcv_scale) 1352 win = (long)TCP_MAXWIN << tp->rcv_scale; 1353 if (win < (long)(int32_t)(tp->rcv_adv - tp->rcv_nxt)) 1354 win = (long)(int32_t)(tp->rcv_adv - tp->rcv_nxt); 1355 th->th_win = htons((u_int16_t) (win>>tp->rcv_scale)); 1356 if (SEQ_GT(tp->snd_up, tp->snd_nxt)) { 1357 u_int32_t urp = tp->snd_up - tp->snd_nxt; 1358 if (urp > IP_MAXPACKET) 1359 urp = IP_MAXPACKET; 1360 th->th_urp = htons((u_int16_t)urp); 1361 th->th_flags |= TH_URG; 1362 } else 1363 /* 1364 * If no urgent pointer to send, then we pull 1365 * the urgent pointer to the left edge of the send window 1366 * so that it doesn't drift into the send window on sequence 1367 * number wraparound. 1368 */ 1369 tp->snd_up = tp->snd_una; /* drag it along */ 1370 1371 #ifdef TCP_SIGNATURE 1372 if (sigoff && (tp->t_flags & TF_SIGNATURE)) { 1373 struct secasvar *sav; 1374 u_int8_t *sigp; 1375 1376 sav = tcp_signature_getsav(m, th); 1377 1378 if (sav == NULL) { 1379 if (m) 1380 m_freem(m); 1381 return (EPERM); 1382 } 1383 1384 m->m_pkthdr.len = hdrlen + len; 1385 sigp = (caddr_t)th + sizeof(*th) + sigoff; 1386 tcp_signature(m, th, (caddr_t)th - mtod(m, caddr_t), sav, sigp); 1387 1388 key_sa_recordxfer(sav, m); 1389 #ifdef FAST_IPSEC 1390 KEY_FREESAV(&sav); 1391 #else 1392 key_freesav(sav); 1393 #endif 1394 } 1395 #endif 1396 1397 /* 1398 * Set ourselves up to be checksummed just before the packet 1399 * hits the wire. 1400 */ 1401 switch (af) { 1402 #ifdef INET 1403 case AF_INET: 1404 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 1405 if (use_tso) { 1406 m->m_pkthdr.segsz = txsegsize; 1407 m->m_pkthdr.csum_flags = M_CSUM_TSOv4; 1408 } else { 1409 m->m_pkthdr.csum_flags = M_CSUM_TCPv4; 1410 if (len + optlen) { 1411 /* Fixup the pseudo-header checksum. */ 1412 /* XXXJRT Not IP Jumbogram safe. */ 1413 th->th_sum = in_cksum_addword(th->th_sum, 1414 htons((u_int16_t) (len + optlen))); 1415 } 1416 } 1417 break; 1418 #endif 1419 #ifdef INET6 1420 case AF_INET6: 1421 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 1422 if (use_tso) { 1423 m->m_pkthdr.segsz = txsegsize; 1424 m->m_pkthdr.csum_flags = M_CSUM_TSOv6; 1425 } else { 1426 m->m_pkthdr.csum_flags = M_CSUM_TCPv6; 1427 if (len + optlen) { 1428 /* Fixup the pseudo-header checksum. */ 1429 /* XXXJRT: Not IPv6 Jumbogram safe. */ 1430 th->th_sum = in_cksum_addword(th->th_sum, 1431 htons((u_int16_t) (len + optlen))); 1432 } 1433 } 1434 break; 1435 #endif 1436 } 1437 1438 /* 1439 * In transmit state, time the transmission and arrange for 1440 * the retransmit. In persist state, just set snd_max. 1441 */ 1442 if (tp->t_force == 0 || TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) { 1443 tcp_seq startseq = tp->snd_nxt; 1444 1445 /* 1446 * Advance snd_nxt over sequence space of this segment. 1447 * There are no states in which we send both a SYN and a FIN, 1448 * so we collapse the tests for these flags. 1449 */ 1450 if (flags & (TH_SYN|TH_FIN)) 1451 tp->snd_nxt++; 1452 if (sack_rxmit) 1453 goto timer; 1454 tp->snd_nxt += len; 1455 if (SEQ_GT(tp->snd_nxt, tp->snd_max)) { 1456 tp->snd_max = tp->snd_nxt; 1457 /* 1458 * Time this transmission if not a retransmission and 1459 * not currently timing anything. 1460 */ 1461 if (tp->t_rtttime == 0) { 1462 tp->t_rtttime = tcp_now; 1463 tp->t_rtseq = startseq; 1464 tcpstat.tcps_segstimed++; 1465 } 1466 } 1467 1468 /* 1469 * Set retransmit timer if not currently set, 1470 * and not doing an ack or a keep-alive probe. 1471 * Initial value for retransmit timer is smoothed 1472 * round-trip time + 2 * round-trip time variance. 1473 * Initialize shift counter which is used for backoff 1474 * of retransmit time. 1475 */ 1476 timer: 1477 if (TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 && 1478 ((sack_rxmit && tp->snd_nxt != tp->snd_max) || 1479 tp->snd_nxt != tp->snd_una)) { 1480 if (TCP_TIMER_ISARMED(tp, TCPT_PERSIST)) { 1481 TCP_TIMER_DISARM(tp, TCPT_PERSIST); 1482 tp->t_rxtshift = 0; 1483 } 1484 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 1485 } 1486 } else 1487 if (SEQ_GT(tp->snd_nxt + len, tp->snd_max)) 1488 tp->snd_max = tp->snd_nxt + len; 1489 1490 #ifdef TCP_DEBUG 1491 /* 1492 * Trace. 1493 */ 1494 if (so->so_options & SO_DEBUG) 1495 tcp_trace(TA_OUTPUT, tp->t_state, tp, m, 0); 1496 #endif 1497 1498 /* 1499 * Fill in IP length and desired time to live and 1500 * send to IP level. There should be a better way 1501 * to handle ttl and tos; we could keep them in 1502 * the template, but need a way to checksum without them. 1503 */ 1504 m->m_pkthdr.len = hdrlen + len; 1505 1506 switch (af) { 1507 #ifdef INET 1508 case AF_INET: 1509 ip->ip_len = htons(m->m_pkthdr.len); 1510 packetlen = m->m_pkthdr.len; 1511 if (tp->t_inpcb) { 1512 ip->ip_ttl = tp->t_inpcb->inp_ip.ip_ttl; 1513 ip->ip_tos = tp->t_inpcb->inp_ip.ip_tos | ecn_tos; 1514 } 1515 #ifdef INET6 1516 else if (tp->t_in6pcb) { 1517 ip->ip_ttl = in6_selecthlim(tp->t_in6pcb, NULL); /*XXX*/ 1518 ip->ip_tos = ecn_tos; /*XXX*/ 1519 } 1520 #endif 1521 break; 1522 #endif 1523 #ifdef INET6 1524 case AF_INET6: 1525 packetlen = m->m_pkthdr.len; 1526 ip6->ip6_nxt = IPPROTO_TCP; 1527 if (tp->t_in6pcb) { 1528 /* 1529 * we separately set hoplimit for every segment, since 1530 * the user might want to change the value via 1531 * setsockopt. Also, desired default hop limit might 1532 * be changed via Neighbor Discovery. 1533 */ 1534 ip6->ip6_hlim = in6_selecthlim(tp->t_in6pcb, 1535 ro->ro_rt ? ro->ro_rt->rt_ifp : NULL); 1536 } 1537 ip6->ip6_flow |= htonl(ecn_tos << 20); 1538 /* ip6->ip6_flow = ??? (from template) */ 1539 /* ip6_plen will be filled in ip6_output(). */ 1540 break; 1541 #endif 1542 default: /*pacify gcc*/ 1543 packetlen = 0; 1544 break; 1545 } 1546 1547 switch (af) { 1548 #ifdef INET 1549 case AF_INET: 1550 { 1551 struct mbuf *opts; 1552 1553 if (tp->t_inpcb) 1554 opts = tp->t_inpcb->inp_options; 1555 else 1556 opts = NULL; 1557 error = ip_output(m, opts, ro, 1558 (tp->t_mtudisc ? IP_MTUDISC : 0) | 1559 (so->so_options & SO_DONTROUTE), 1560 (struct ip_moptions *)0, so); 1561 break; 1562 } 1563 #endif 1564 #ifdef INET6 1565 case AF_INET6: 1566 { 1567 struct ip6_pktopts *opts; 1568 1569 if (tp->t_in6pcb) 1570 opts = tp->t_in6pcb->in6p_outputopts; 1571 else 1572 opts = NULL; 1573 error = ip6_output(m, opts, (struct route_in6 *)ro, 1574 so->so_options & SO_DONTROUTE, 1575 (struct ip6_moptions *)0, so, NULL); 1576 break; 1577 } 1578 #endif 1579 default: 1580 error = EAFNOSUPPORT; 1581 break; 1582 } 1583 if (error) { 1584 out: 1585 if (error == ENOBUFS) { 1586 tcpstat.tcps_selfquench++; 1587 #ifdef INET 1588 if (tp->t_inpcb) 1589 tcp_quench(tp->t_inpcb, 0); 1590 #endif 1591 #ifdef INET6 1592 if (tp->t_in6pcb) 1593 tcp6_quench(tp->t_in6pcb, 0); 1594 #endif 1595 error = 0; 1596 } else if ((error == EHOSTUNREACH || error == ENETDOWN) && 1597 TCPS_HAVERCVDSYN(tp->t_state)) { 1598 tp->t_softerror = error; 1599 error = 0; 1600 } 1601 1602 /* Back out the seqence number advance. */ 1603 if (sack_rxmit) 1604 p->rxmit -= len; 1605 1606 /* Restart the delayed ACK timer, if necessary. */ 1607 if (tp->t_flags & TF_DELACK) 1608 TCP_RESTART_DELACK(tp); 1609 1610 return (error); 1611 } 1612 1613 if (packetlen > tp->t_pmtud_mtu_sent) 1614 tp->t_pmtud_mtu_sent = packetlen; 1615 1616 tcpstat.tcps_sndtotal++; 1617 if (tp->t_flags & TF_DELACK) 1618 tcpstat.tcps_delack++; 1619 1620 /* 1621 * Data sent (as far as we can tell). 1622 * If this advertises a larger window than any other segment, 1623 * then remember the size of the advertised window. 1624 * Any pending ACK has now been sent. 1625 */ 1626 if (win > 0 && SEQ_GT(tp->rcv_nxt+win, tp->rcv_adv)) 1627 tp->rcv_adv = tp->rcv_nxt + win; 1628 tp->last_ack_sent = tp->rcv_nxt; 1629 tp->t_flags &= ~TF_ACKNOW; 1630 TCP_CLEAR_DELACK(tp); 1631 #ifdef DIAGNOSTIC 1632 if (maxburst < 0) 1633 printf("tcp_output: maxburst exceeded by %d\n", -maxburst); 1634 #endif 1635 if (sendalot && (tp->t_congctl == &tcp_reno_ctl || --maxburst)) 1636 goto again; 1637 return (0); 1638 } 1639 1640 void 1641 tcp_setpersist(struct tcpcb *tp) 1642 { 1643 int t = ((tp->t_srtt >> 2) + tp->t_rttvar) >> (1 + 2); 1644 int nticks; 1645 1646 if (TCP_TIMER_ISARMED(tp, TCPT_REXMT)) 1647 panic("tcp_output REXMT"); 1648 /* 1649 * Start/restart persistance timer. 1650 */ 1651 if (t < tp->t_rttmin) 1652 t = tp->t_rttmin; 1653 TCPT_RANGESET(nticks, t * tcp_backoff[tp->t_rxtshift], 1654 TCPTV_PERSMIN, TCPTV_PERSMAX); 1655 TCP_TIMER_ARM(tp, TCPT_PERSIST, nticks); 1656 if (tp->t_rxtshift < TCP_MAXRXTSHIFT) 1657 tp->t_rxtshift++; 1658 }
Cache object: 1f537d6a529ac49f76c6fd5c7df5491c
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