tcp_output.c revision 1.201
1 /* $NetBSD: tcp_output.c,v 1.201 2018/03/30 08:53:51 maxv 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 * 93 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 94 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 95 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 96 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 97 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 98 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 99 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 100 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 101 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 102 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 103 * POSSIBILITY OF SUCH DAMAGE. 104 */ 105 106 /* 107 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995 108 * The Regents of the University of California. All rights reserved. 109 * 110 * Redistribution and use in source and binary forms, with or without 111 * modification, are permitted provided that the following conditions 112 * are met: 113 * 1. Redistributions of source code must retain the above copyright 114 * notice, this list of conditions and the following disclaimer. 115 * 2. Redistributions in binary form must reproduce the above copyright 116 * notice, this list of conditions and the following disclaimer in the 117 * documentation and/or other materials provided with the distribution. 118 * 3. Neither the name of the University nor the names of its contributors 119 * may be used to endorse or promote products derived from this software 120 * without specific prior written permission. 121 * 122 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 123 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 124 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 125 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 126 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 127 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 128 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 129 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 130 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 131 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 132 * SUCH DAMAGE. 133 * 134 * @(#)tcp_output.c 8.4 (Berkeley) 5/24/95 135 */ 136 137 #include <sys/cdefs.h> 138 __KERNEL_RCSID(0, "$NetBSD: tcp_output.c,v 1.201 2018/03/30 08:53:51 maxv Exp $"); 139 140 #ifdef _KERNEL_OPT 141 #include "opt_inet.h" 142 #include "opt_ipsec.h" 143 #include "opt_tcp_debug.h" 144 #endif 145 146 #include <sys/param.h> 147 #include <sys/systm.h> 148 #include <sys/mbuf.h> 149 #include <sys/protosw.h> 150 #include <sys/socket.h> 151 #include <sys/socketvar.h> 152 #include <sys/errno.h> 153 #include <sys/domain.h> 154 #include <sys/kernel.h> 155 #ifdef TCP_SIGNATURE 156 #include <sys/md5.h> 157 #endif 158 159 #include <net/if.h> 160 #include <net/route.h> 161 162 #include <netinet/in.h> 163 #include <netinet/in_systm.h> 164 #include <netinet/ip.h> 165 #include <netinet/in_pcb.h> 166 #include <netinet/ip_var.h> 167 168 #ifdef INET6 169 #include <netinet/ip6.h> 170 #include <netinet6/in6_var.h> 171 #include <netinet6/ip6_var.h> 172 #include <netinet6/in6_pcb.h> 173 #include <netinet6/nd6.h> 174 #endif 175 176 #ifdef IPSEC 177 #include <netipsec/ipsec.h> 178 #include <netipsec/key.h> 179 #ifdef INET6 180 #include <netipsec/ipsec6.h> 181 #endif 182 #endif 183 184 #include <netinet/tcp.h> 185 #define TCPOUTFLAGS 186 #include <netinet/tcp_fsm.h> 187 #include <netinet/tcp_seq.h> 188 #include <netinet/tcp_timer.h> 189 #include <netinet/tcp_var.h> 190 #include <netinet/tcp_private.h> 191 #include <netinet/tcp_congctl.h> 192 #include <netinet/tcpip.h> 193 #include <netinet/tcp_debug.h> 194 #include <netinet/in_offload.h> 195 #include <netinet6/in6_offload.h> 196 197 #ifdef notyet 198 extern struct mbuf *m_copypack(); 199 #endif 200 201 /* 202 * Knob to enable Congestion Window Monitoring, and control 203 * the burst size it allows. Default burst is 4 packets, per 204 * the Internet draft. 205 */ 206 int tcp_cwm = 0; 207 int tcp_cwm_burstsize = 4; 208 209 int tcp_do_autosndbuf = 1; 210 int tcp_autosndbuf_inc = 8 * 1024; 211 int tcp_autosndbuf_max = 256 * 1024; 212 213 #ifdef TCP_OUTPUT_COUNTERS 214 #include <sys/device.h> 215 216 extern struct evcnt tcp_output_bigheader; 217 extern struct evcnt tcp_output_predict_hit; 218 extern struct evcnt tcp_output_predict_miss; 219 extern struct evcnt tcp_output_copysmall; 220 extern struct evcnt tcp_output_copybig; 221 extern struct evcnt tcp_output_refbig; 222 223 #define TCP_OUTPUT_COUNTER_INCR(ev) (ev)->ev_count++ 224 #else 225 226 #define TCP_OUTPUT_COUNTER_INCR(ev) /* nothing */ 227 228 #endif /* TCP_OUTPUT_COUNTERS */ 229 230 static int 231 tcp_segsize(struct tcpcb *tp, int *txsegsizep, int *rxsegsizep, 232 bool *alwaysfragp) 233 { 234 struct inpcb *inp = tp->t_inpcb; 235 #ifdef INET6 236 struct in6pcb *in6p = tp->t_in6pcb; 237 #endif 238 struct socket *so = NULL; 239 struct rtentry *rt; 240 struct ifnet *ifp; 241 int size; 242 int hdrlen; 243 int optlen; 244 245 *alwaysfragp = false; 246 247 KASSERT(!(tp->t_inpcb && tp->t_in6pcb)); 248 249 switch (tp->t_family) { 250 case AF_INET: 251 hdrlen = sizeof(struct ip) + sizeof(struct tcphdr); 252 break; 253 #ifdef INET6 254 case AF_INET6: 255 hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 256 break; 257 #endif 258 default: 259 size = tcp_mssdflt; 260 goto out; 261 } 262 263 rt = NULL; 264 if (inp) { 265 rt = in_pcbrtentry(inp); 266 so = inp->inp_socket; 267 } 268 #ifdef INET6 269 if (in6p) { 270 rt = in6_pcbrtentry(in6p); 271 so = in6p->in6p_socket; 272 } 273 #endif 274 if (rt == NULL) { 275 size = tcp_mssdflt; 276 goto out; 277 } 278 279 ifp = rt->rt_ifp; 280 281 size = tcp_mssdflt; 282 if (tp->t_mtudisc && rt->rt_rmx.rmx_mtu != 0) { 283 #ifdef INET6 284 if (in6p && rt->rt_rmx.rmx_mtu < IPV6_MMTU) { 285 /* 286 * RFC2460 section 5, last paragraph: if path MTU is 287 * smaller than 1280, use 1280 as packet size and 288 * attach fragment header. 289 */ 290 size = IPV6_MMTU - hdrlen - sizeof(struct ip6_frag); 291 *alwaysfragp = true; 292 } else 293 size = rt->rt_rmx.rmx_mtu - hdrlen; 294 #else 295 size = rt->rt_rmx.rmx_mtu - hdrlen; 296 #endif 297 } else if (ifp->if_flags & IFF_LOOPBACK) 298 size = ifp->if_mtu - hdrlen; 299 else if (inp && tp->t_mtudisc) 300 size = ifp->if_mtu - hdrlen; 301 else if (inp && in_localaddr(inp->inp_faddr)) 302 size = ifp->if_mtu - hdrlen; 303 #ifdef INET6 304 else if (in6p) { 305 if (IN6_IS_ADDR_V4MAPPED(&in6p->in6p_faddr)) { 306 /* mapped addr case */ 307 struct in_addr d; 308 bcopy(&in6p->in6p_faddr.s6_addr32[3], &d, sizeof(d)); 309 if (tp->t_mtudisc || in_localaddr(d)) 310 size = ifp->if_mtu - hdrlen; 311 } else { 312 /* 313 * for IPv6, path MTU discovery is always turned on, 314 * or the node must use packet size <= 1280. 315 */ 316 size = tp->t_mtudisc ? IN6_LINKMTU(ifp) : IPV6_MMTU; 317 size -= hdrlen; 318 } 319 } 320 #endif 321 if (inp) 322 in_pcbrtentry_unref(rt, inp); 323 #ifdef INET6 324 if (in6p) 325 in6_pcbrtentry_unref(rt, in6p); 326 #endif 327 out: 328 /* 329 * Now we must make room for whatever extra TCP/IP options are in 330 * the packet. 331 */ 332 optlen = tcp_optlen(tp); 333 334 /* 335 * XXX tp->t_ourmss should have the right size, but without this code 336 * fragmentation will occur... need more investigation 337 */ 338 339 if (inp) { 340 #if defined(IPSEC) 341 if (ipsec_used && 342 !ipsec_pcb_skip_ipsec(inp->inp_sp, IPSEC_DIR_OUTBOUND)) 343 optlen += ipsec4_hdrsiz_tcp(tp); 344 #endif 345 optlen += ip_optlen(inp); 346 } 347 348 #ifdef INET6 349 if (in6p && tp->t_family == AF_INET) { 350 #if defined(IPSEC) 351 if (ipsec_used && 352 !ipsec_pcb_skip_ipsec(in6p->in6p_sp, IPSEC_DIR_OUTBOUND)) 353 optlen += ipsec4_hdrsiz_tcp(tp); 354 #endif 355 /* XXX size -= ip_optlen(in6p); */ 356 } else if (in6p && tp->t_family == AF_INET6) { 357 #if defined(IPSEC) 358 if (ipsec_used && 359 !ipsec_pcb_skip_ipsec(in6p->in6p_sp, IPSEC_DIR_OUTBOUND)) 360 optlen += ipsec6_hdrsiz_tcp(tp); 361 #endif 362 optlen += ip6_optlen(in6p); 363 } 364 #endif 365 size -= optlen; 366 367 /* there may not be any room for data if mtu is too small */ 368 if (size < 0) 369 return EMSGSIZE; 370 371 /* 372 * *rxsegsizep holds *estimated* inbound segment size (estimation 373 * assumes that path MTU is the same for both ways). this is only 374 * for silly window avoidance, do not use the value for other purposes. 375 * 376 * ipseclen is subtracted from both sides, this may not be right. 377 * I'm not quite sure about this (could someone comment). 378 */ 379 *txsegsizep = min(tp->t_peermss - optlen, size); 380 /* 381 * Never send more than half a buffer full. This insures that we can 382 * always keep 2 packets on the wire, no matter what SO_SNDBUF is, and 383 * therefore acks will never be delayed unless we run out of data to 384 * transmit. 385 */ 386 if (so) 387 *txsegsizep = min(so->so_snd.sb_hiwat >> 1, *txsegsizep); 388 *rxsegsizep = min(tp->t_ourmss - optlen, size); 389 390 if (*txsegsizep != tp->t_segsz) { 391 /* 392 * If the new segment size is larger, we don't want to 393 * mess up the congestion window, but if it is smaller 394 * we'll have to reduce the congestion window to ensure 395 * that we don't get into trouble with initial windows 396 * and the rest. In any case, if the segment size 397 * has changed, chances are the path has, too, and 398 * our congestion window will be different. 399 */ 400 if (*txsegsizep < tp->t_segsz) { 401 tp->snd_cwnd = max((tp->snd_cwnd / tp->t_segsz) 402 * *txsegsizep, *txsegsizep); 403 tp->snd_ssthresh = max((tp->snd_ssthresh / tp->t_segsz) 404 * *txsegsizep, *txsegsizep); 405 } 406 tp->t_segsz = *txsegsizep; 407 } 408 409 return 0; 410 } 411 412 static int 413 tcp_build_datapkt(struct tcpcb *tp, struct socket *so, int off, 414 long len, int hdrlen, struct mbuf **mp) 415 { 416 struct mbuf *m, *m0; 417 uint64_t *tcps; 418 419 tcps = TCP_STAT_GETREF(); 420 if (tp->t_force && len == 1) 421 tcps[TCP_STAT_SNDPROBE]++; 422 else if (SEQ_LT(tp->snd_nxt, tp->snd_max)) { 423 tp->t_sndrexmitpack++; 424 tcps[TCP_STAT_SNDREXMITPACK]++; 425 tcps[TCP_STAT_SNDREXMITBYTE] += len; 426 } else { 427 tcps[TCP_STAT_SNDPACK]++; 428 tcps[TCP_STAT_SNDBYTE] += len; 429 } 430 TCP_STAT_PUTREF(); 431 #ifdef notyet 432 if ((m = m_copypack(so->so_snd.sb_mb, off, 433 (int)len, max_linkhdr + hdrlen)) == 0) 434 return ENOBUFS; 435 /* 436 * m_copypack left space for our hdr; use it. 437 */ 438 m->m_len += hdrlen; 439 m->m_data -= hdrlen; 440 #else 441 MGETHDR(m, M_DONTWAIT, MT_HEADER); 442 if (__predict_false(m == NULL)) 443 return ENOBUFS; 444 MCLAIM(m, &tcp_tx_mowner); 445 446 /* 447 * XXX Because other code assumes headers will fit in 448 * XXX one header mbuf. 449 * 450 * (This code should almost *never* be run.) 451 */ 452 if (__predict_false((max_linkhdr + hdrlen) > MHLEN)) { 453 TCP_OUTPUT_COUNTER_INCR(&tcp_output_bigheader); 454 MCLGET(m, M_DONTWAIT); 455 if ((m->m_flags & M_EXT) == 0) { 456 m_freem(m); 457 return ENOBUFS; 458 } 459 } 460 461 m->m_data += max_linkhdr; 462 m->m_len = hdrlen; 463 464 /* 465 * To avoid traversing the whole sb_mb chain for correct 466 * data to send, remember last sent mbuf, its offset and 467 * the sent size. When called the next time, see if the 468 * data to send is directly following the previous transfer. 469 * This is important for large TCP windows. 470 */ 471 if (off == 0 || tp->t_lastm == NULL || 472 (tp->t_lastoff + tp->t_lastlen) != off) { 473 TCP_OUTPUT_COUNTER_INCR(&tcp_output_predict_miss); 474 /* 475 * Either a new packet or a retransmit. 476 * Start from the beginning. 477 */ 478 tp->t_lastm = so->so_snd.sb_mb; 479 tp->t_inoff = off; 480 } else { 481 TCP_OUTPUT_COUNTER_INCR(&tcp_output_predict_hit); 482 tp->t_inoff += tp->t_lastlen; 483 } 484 485 /* Traverse forward to next packet */ 486 while (tp->t_inoff > 0) { 487 if (tp->t_lastm == NULL) 488 panic("tp->t_lastm == NULL"); 489 if (tp->t_inoff < tp->t_lastm->m_len) 490 break; 491 tp->t_inoff -= tp->t_lastm->m_len; 492 tp->t_lastm = tp->t_lastm->m_next; 493 } 494 495 tp->t_lastoff = off; 496 tp->t_lastlen = len; 497 m0 = tp->t_lastm; 498 off = tp->t_inoff; 499 500 if (len <= M_TRAILINGSPACE(m)) { 501 m_copydata(m0, off, (int)len, mtod(m, char *) + hdrlen); 502 m->m_len += len; 503 TCP_OUTPUT_COUNTER_INCR(&tcp_output_copysmall); 504 } else { 505 m->m_next = m_copym(m0, off, (int)len, M_DONTWAIT); 506 if (m->m_next == NULL) { 507 m_freem(m); 508 return ENOBUFS; 509 } 510 #ifdef TCP_OUTPUT_COUNTERS 511 if (m->m_next->m_flags & M_EXT) 512 TCP_OUTPUT_COUNTER_INCR(&tcp_output_refbig); 513 else 514 TCP_OUTPUT_COUNTER_INCR(&tcp_output_copybig); 515 #endif 516 } 517 #endif 518 519 *mp = m; 520 return 0; 521 } 522 523 /* 524 * Tcp output routine: figure out what should be sent and send it. 525 */ 526 int 527 tcp_output(struct tcpcb *tp) 528 { 529 struct rtentry *rt = NULL; 530 struct socket *so; 531 struct route *ro; 532 long len, win; 533 int off, flags, error; 534 struct mbuf *m; 535 struct ip *ip; 536 #ifdef INET6 537 struct ip6_hdr *ip6; 538 #endif 539 struct tcphdr *th; 540 u_char opt[MAX_TCPOPTLEN], *optp; 541 #define OPT_FITS(more) ((optlen + (more)) <= sizeof(opt)) 542 unsigned optlen, hdrlen, packetlen; 543 unsigned int sack_numblks; 544 int idle, sendalot, txsegsize, rxsegsize; 545 int txsegsize_nosack; 546 int maxburst = TCP_MAXBURST; 547 int af; /* address family on the wire */ 548 int iphdrlen; 549 int has_tso4, has_tso6; 550 int has_tso, use_tso; 551 bool alwaysfrag; 552 int sack_rxmit; 553 int sack_bytes_rxmt; 554 int ecn_tos; 555 struct sackhole *p; 556 #ifdef TCP_SIGNATURE 557 int sigoff = 0; 558 #endif 559 uint64_t *tcps; 560 561 KASSERT(!(tp->t_inpcb && tp->t_in6pcb)); 562 563 so = NULL; 564 ro = NULL; 565 if (tp->t_inpcb) { 566 so = tp->t_inpcb->inp_socket; 567 ro = &tp->t_inpcb->inp_route; 568 } 569 #ifdef INET6 570 else if (tp->t_in6pcb) { 571 so = tp->t_in6pcb->in6p_socket; 572 ro = &tp->t_in6pcb->in6p_route; 573 } 574 #endif 575 576 switch (af = tp->t_family) { 577 case AF_INET: 578 if (tp->t_inpcb) 579 break; 580 #ifdef INET6 581 /* mapped addr case */ 582 if (tp->t_in6pcb) 583 break; 584 #endif 585 return EINVAL; 586 #ifdef INET6 587 case AF_INET6: 588 if (tp->t_in6pcb) 589 break; 590 return EINVAL; 591 #endif 592 default: 593 return EAFNOSUPPORT; 594 } 595 596 if (tcp_segsize(tp, &txsegsize, &rxsegsize, &alwaysfrag)) 597 return EMSGSIZE; 598 599 idle = (tp->snd_max == tp->snd_una); 600 601 /* 602 * Determine if we can use TCP segmentation offload: 603 * - If we're using IPv4 604 * - If there is not an IPsec policy that prevents it 605 * - If the interface can do it 606 */ 607 has_tso4 = has_tso6 = false; 608 609 has_tso4 = tp->t_inpcb != NULL && 610 #if defined(IPSEC) 611 (!ipsec_used || ipsec_pcb_skip_ipsec(tp->t_inpcb->inp_sp, 612 IPSEC_DIR_OUTBOUND)) && 613 #endif 614 (rt = rtcache_validate(&tp->t_inpcb->inp_route)) != NULL && 615 (rt->rt_ifp->if_capenable & IFCAP_TSOv4) != 0; 616 if (rt != NULL) { 617 rtcache_unref(rt, &tp->t_inpcb->inp_route); 618 rt = NULL; 619 } 620 621 #if defined(INET6) 622 has_tso6 = tp->t_in6pcb != NULL && 623 #if defined(IPSEC) 624 (!ipsec_used || ipsec_pcb_skip_ipsec(tp->t_in6pcb->in6p_sp, 625 IPSEC_DIR_OUTBOUND)) && 626 #endif 627 (rt = rtcache_validate(&tp->t_in6pcb->in6p_route)) != NULL && 628 (rt->rt_ifp->if_capenable & IFCAP_TSOv6) != 0; 629 if (rt != NULL) 630 rtcache_unref(rt, &tp->t_in6pcb->in6p_route); 631 #endif /* defined(INET6) */ 632 has_tso = (has_tso4 || has_tso6) && !alwaysfrag; 633 634 /* 635 * Restart Window computation. From draft-floyd-incr-init-win-03: 636 * 637 * Optionally, a TCP MAY set the restart window to the 638 * minimum of the value used for the initial window and 639 * the current value of cwnd (in other words, using a 640 * larger value for the restart window should never increase 641 * the size of cwnd). 642 */ 643 if (tcp_cwm) { 644 /* 645 * Hughes/Touch/Heidemann Congestion Window Monitoring. 646 * Count the number of packets currently pending 647 * acknowledgement, and limit our congestion window 648 * to a pre-determined allowed burst size plus that count. 649 * This prevents bursting once all pending packets have 650 * been acknowledged (i.e. transmission is idle). 651 * 652 * XXX Link this to Initial Window? 653 */ 654 tp->snd_cwnd = min(tp->snd_cwnd, 655 (tcp_cwm_burstsize * txsegsize) + 656 (tp->snd_nxt - tp->snd_una)); 657 } else { 658 if (idle && (tcp_now - tp->t_rcvtime) >= tp->t_rxtcur) { 659 /* 660 * We have been idle for "a while" and no acks are 661 * expected to clock out any data we send -- 662 * slow start to get ack "clock" running again. 663 */ 664 int ss = tcp_init_win; 665 if (tp->t_inpcb && 666 in_localaddr(tp->t_inpcb->inp_faddr)) 667 ss = tcp_init_win_local; 668 #ifdef INET6 669 if (tp->t_in6pcb && 670 in6_localaddr(&tp->t_in6pcb->in6p_faddr)) 671 ss = tcp_init_win_local; 672 #endif 673 tp->snd_cwnd = min(tp->snd_cwnd, 674 TCP_INITIAL_WINDOW(ss, txsegsize)); 675 } 676 } 677 678 txsegsize_nosack = txsegsize; 679 again: 680 ecn_tos = 0; 681 use_tso = has_tso; 682 if ((tp->t_flags & (TF_ECN_SND_CWR|TF_ECN_SND_ECE)) != 0) { 683 /* don't duplicate CWR/ECE. */ 684 use_tso = 0; 685 } 686 TCP_REASS_LOCK(tp); 687 sack_numblks = tcp_sack_numblks(tp); 688 if (sack_numblks) { 689 int sackoptlen; 690 691 sackoptlen = TCP_SACK_OPTLEN(sack_numblks); 692 if (sackoptlen > txsegsize_nosack) { 693 sack_numblks = 0; /* give up SACK */ 694 txsegsize = txsegsize_nosack; 695 } else { 696 if ((tp->rcv_sack_flags & TCPSACK_HAVED) != 0) { 697 /* don't duplicate D-SACK. */ 698 use_tso = 0; 699 } 700 txsegsize = txsegsize_nosack - sackoptlen; 701 } 702 } else { 703 txsegsize = txsegsize_nosack; 704 } 705 706 /* 707 * Determine length of data that should be transmitted, and 708 * flags that should be used. If there is some data or critical 709 * controls (SYN, RST) to send, then transmit; otherwise, 710 * investigate further. 711 * 712 * Readjust SACK information to avoid resending duplicate data. 713 */ 714 if (TCP_SACK_ENABLED(tp) && SEQ_LT(tp->snd_nxt, tp->snd_max)) 715 tcp_sack_adjust(tp); 716 sendalot = 0; 717 off = tp->snd_nxt - tp->snd_una; 718 win = min(tp->snd_wnd, tp->snd_cwnd); 719 720 flags = tcp_outflags[tp->t_state]; 721 722 /* 723 * Send any SACK-generated retransmissions. If we're explicitly trying 724 * to send out new data (when sendalot is 1), bypass this function. 725 * If we retransmit in fast recovery mode, decrement snd_cwnd, since 726 * we're replacing a (future) new transmission with a retransmission 727 * now, and we previously incremented snd_cwnd in tcp_input(). 728 */ 729 /* 730 * Still in sack recovery, reset rxmit flag to zero. 731 */ 732 sack_rxmit = 0; 733 sack_bytes_rxmt = 0; 734 len = 0; 735 p = NULL; 736 do { 737 long cwin; 738 if (!TCP_SACK_ENABLED(tp)) 739 break; 740 if (tp->t_partialacks < 0) 741 break; 742 p = tcp_sack_output(tp, &sack_bytes_rxmt); 743 if (p == NULL) 744 break; 745 746 cwin = min(tp->snd_wnd, tp->snd_cwnd) - sack_bytes_rxmt; 747 if (cwin < 0) 748 cwin = 0; 749 /* Do not retransmit SACK segments beyond snd_recover */ 750 if (SEQ_GT(p->end, tp->snd_recover)) { 751 /* 752 * (At least) part of sack hole extends beyond 753 * snd_recover. Check to see if we can rexmit data 754 * for this hole. 755 */ 756 if (SEQ_GEQ(p->rxmit, tp->snd_recover)) { 757 /* 758 * Can't rexmit any more data for this hole. 759 * That data will be rexmitted in the next 760 * sack recovery episode, when snd_recover 761 * moves past p->rxmit. 762 */ 763 p = NULL; 764 break; 765 } 766 /* Can rexmit part of the current hole */ 767 len = ((long)ulmin(cwin, tp->snd_recover - p->rxmit)); 768 } else 769 len = ((long)ulmin(cwin, p->end - p->rxmit)); 770 off = p->rxmit - tp->snd_una; 771 if (off + len > so->so_snd.sb_cc) { 772 /* 1 for TH_FIN */ 773 KASSERT(off + len == so->so_snd.sb_cc + 1); 774 KASSERT(p->rxmit + len == tp->snd_max); 775 len = so->so_snd.sb_cc - off; 776 } 777 if (len > 0) { 778 sack_rxmit = 1; 779 sendalot = 1; 780 } 781 } while (/*CONSTCOND*/0); 782 783 /* 784 * If in persist timeout with window of 0, send 1 byte. 785 * Otherwise, if window is small but nonzero 786 * and timer expired, we will send what we can 787 * and go to transmit state. 788 */ 789 if (tp->t_force) { 790 if (win == 0) { 791 /* 792 * If we still have some data to send, then 793 * clear the FIN bit. Usually this would 794 * happen below when it realizes that we 795 * aren't sending all the data. However, 796 * if we have exactly 1 byte of unset data, 797 * then it won't clear the FIN bit below, 798 * and if we are in persist state, we wind 799 * up sending the packet without recording 800 * that we sent the FIN bit. 801 * 802 * We can't just blindly clear the FIN bit, 803 * because if we don't have any more data 804 * to send then the probe will be the FIN 805 * itself. 806 */ 807 if (off < so->so_snd.sb_cc) 808 flags &= ~TH_FIN; 809 win = 1; 810 } else { 811 TCP_TIMER_DISARM(tp, TCPT_PERSIST); 812 tp->t_rxtshift = 0; 813 } 814 } 815 816 if (sack_rxmit == 0) { 817 if (TCP_SACK_ENABLED(tp) && tp->t_partialacks >= 0) { 818 long cwin; 819 820 /* 821 * We are inside of a SACK recovery episode and are 822 * sending new data, having retransmitted all the 823 * data possible in the scoreboard. 824 */ 825 if (tp->snd_wnd < so->so_snd.sb_cc) { 826 len = tp->snd_wnd - off; 827 flags &= ~TH_FIN; 828 } else { 829 len = so->so_snd.sb_cc - off; 830 } 831 832 /* 833 * From FreeBSD: 834 * Don't remove this (len > 0) check ! 835 * We explicitly check for len > 0 here (although it 836 * isn't really necessary), to work around a gcc 837 * optimization issue - to force gcc to compute 838 * len above. Without this check, the computation 839 * of len is bungled by the optimizer. 840 */ 841 if (len > 0) { 842 cwin = tp->snd_cwnd - 843 (tp->snd_nxt - tp->sack_newdata) - 844 sack_bytes_rxmt; 845 if (cwin < 0) 846 cwin = 0; 847 if (cwin < len) { 848 len = cwin; 849 flags &= ~TH_FIN; 850 } 851 } 852 } else if (win < so->so_snd.sb_cc) { 853 len = win - off; 854 flags &= ~TH_FIN; 855 } else { 856 len = so->so_snd.sb_cc - off; 857 } 858 } 859 860 if (len < 0) { 861 /* 862 * If FIN has been sent but not acked, 863 * but we haven't been called to retransmit, 864 * len will be -1. Otherwise, window shrank 865 * after we sent into it. If window shrank to 0, 866 * cancel pending retransmit, pull snd_nxt back 867 * to (closed) window, and set the persist timer 868 * if it isn't already going. If the window didn't 869 * close completely, just wait for an ACK. 870 * 871 * If we have a pending FIN, either it has already been 872 * transmitted or it is outside the window, so drop it. 873 * If the FIN has been transmitted, but this is not a 874 * retransmission, then len must be -1. Therefore we also 875 * prevent here the sending of `gratuitous FINs'. This 876 * eliminates the need to check for that case below (e.g. 877 * to back up snd_nxt before the FIN so that the sequence 878 * number is correct). 879 */ 880 len = 0; 881 flags &= ~TH_FIN; 882 if (win == 0) { 883 TCP_TIMER_DISARM(tp, TCPT_REXMT); 884 tp->t_rxtshift = 0; 885 tp->snd_nxt = tp->snd_una; 886 if (TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) 887 tcp_setpersist(tp); 888 } 889 } 890 891 /* 892 * Automatic sizing enables the performance of large buffers 893 * and most of the efficiency of small ones by only allocating 894 * space when it is needed. 895 * 896 * The criteria to step up the send buffer one notch are: 897 * 1. receive window of remote host is larger than send buffer 898 * (with a fudge factor of 5/4th); 899 * 2. send buffer is filled to 7/8th with data (so we actually 900 * have data to make use of it); 901 * 3. send buffer fill has not hit maximal automatic size; 902 * 4. our send window (slow start and cogestion controlled) is 903 * larger than sent but unacknowledged data in send buffer. 904 * 905 * The remote host receive window scaling factor may limit the 906 * growing of the send buffer before it reaches its allowed 907 * maximum. 908 * 909 * It scales directly with slow start or congestion window 910 * and does at most one step per received ACK. This fast 911 * scaling has the drawback of growing the send buffer beyond 912 * what is strictly necessary to make full use of a given 913 * delay*bandwith product. However testing has shown this not 914 * to be much of an problem. At worst we are trading wasting 915 * of available bandwith (the non-use of it) for wasting some 916 * socket buffer memory. 917 * 918 * TODO: Shrink send buffer during idle periods together 919 * with congestion window. Requires another timer. 920 */ 921 if (tcp_do_autosndbuf && so->so_snd.sb_flags & SB_AUTOSIZE) { 922 if ((tp->snd_wnd / 4 * 5) >= so->so_snd.sb_hiwat && 923 so->so_snd.sb_cc >= (so->so_snd.sb_hiwat / 8 * 7) && 924 so->so_snd.sb_cc < tcp_autosndbuf_max && 925 win >= (so->so_snd.sb_cc - (tp->snd_nxt - tp->snd_una))) { 926 if (!sbreserve(&so->so_snd, 927 min(so->so_snd.sb_hiwat + tcp_autosndbuf_inc, 928 tcp_autosndbuf_max), so)) 929 so->so_snd.sb_flags &= ~SB_AUTOSIZE; 930 } 931 } 932 933 if (len > txsegsize) { 934 if (use_tso) { 935 /* 936 * Truncate TSO transfers to IP_MAXPACKET, and make 937 * sure that we send equal size transfers down the 938 * stack (rather than big-small-big-small-...). 939 */ 940 #ifdef INET6 941 CTASSERT(IPV6_MAXPACKET == IP_MAXPACKET); 942 #endif 943 len = (min(len, IP_MAXPACKET) / txsegsize) * txsegsize; 944 if (len <= txsegsize) { 945 use_tso = 0; 946 } 947 } else 948 len = txsegsize; 949 flags &= ~TH_FIN; 950 sendalot = 1; 951 } else 952 use_tso = 0; 953 if (sack_rxmit) { 954 if (SEQ_LT(p->rxmit + len, tp->snd_una + so->so_snd.sb_cc)) 955 flags &= ~TH_FIN; 956 } 957 958 win = sbspace(&so->so_rcv); 959 960 /* 961 * Sender silly window avoidance. If connection is idle 962 * and can send all data, a maximum segment, 963 * at least a maximum default-size segment do it, 964 * or are forced, do it; otherwise don't bother. 965 * If peer's buffer is tiny, then send 966 * when window is at least half open. 967 * If retransmitting (possibly after persist timer forced us 968 * to send into a small window), then must resend. 969 */ 970 if (len) { 971 if (len >= txsegsize) 972 goto send; 973 if ((so->so_state & SS_MORETOCOME) == 0 && 974 ((idle || tp->t_flags & TF_NODELAY) && 975 len + off >= so->so_snd.sb_cc)) 976 goto send; 977 if (tp->t_force) 978 goto send; 979 if (len >= tp->max_sndwnd / 2) 980 goto send; 981 if (SEQ_LT(tp->snd_nxt, tp->snd_max)) 982 goto send; 983 if (sack_rxmit) 984 goto send; 985 } 986 987 /* 988 * Compare available window to amount of window known to peer 989 * (as advertised window less next expected input). If the 990 * difference is at least twice the size of the largest segment 991 * we expect to receive (i.e. two segments) or at least 50% of 992 * the maximum possible window, then want to send a window update 993 * to peer. 994 */ 995 if (win > 0) { 996 /* 997 * "adv" is the amount we can increase the window, 998 * taking into account that we are limited by 999 * TCP_MAXWIN << tp->rcv_scale. 1000 */ 1001 long adv = min(win, (long)TCP_MAXWIN << tp->rcv_scale) - 1002 (tp->rcv_adv - tp->rcv_nxt); 1003 1004 /* 1005 * If the new window size ends up being the same as the old 1006 * size when it is scaled, then don't force a window update. 1007 */ 1008 if ((tp->rcv_adv - tp->rcv_nxt) >> tp->rcv_scale == 1009 (adv + tp->rcv_adv - tp->rcv_nxt) >> tp->rcv_scale) 1010 goto dontupdate; 1011 if (adv >= (long) (2 * rxsegsize)) 1012 goto send; 1013 if (2 * adv >= (long) so->so_rcv.sb_hiwat) 1014 goto send; 1015 } 1016 dontupdate: 1017 1018 /* 1019 * Send if we owe peer an ACK. 1020 */ 1021 if (tp->t_flags & TF_ACKNOW) 1022 goto send; 1023 if (flags & (TH_SYN|TH_FIN|TH_RST)) 1024 goto send; 1025 if (SEQ_GT(tp->snd_up, tp->snd_una)) 1026 goto send; 1027 /* 1028 * In SACK, it is possible for tcp_output to fail to send a segment 1029 * after the retransmission timer has been turned off. Make sure 1030 * that the retransmission timer is set. 1031 */ 1032 if (TCP_SACK_ENABLED(tp) && SEQ_GT(tp->snd_max, tp->snd_una) && 1033 !TCP_TIMER_ISARMED(tp, TCPT_REXMT) && 1034 !TCP_TIMER_ISARMED(tp, TCPT_PERSIST)) { 1035 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 1036 goto just_return; 1037 } 1038 1039 /* 1040 * TCP window updates are not reliable, rather a polling protocol 1041 * using ``persist'' packets is used to insure receipt of window 1042 * updates. The three ``states'' for the output side are: 1043 * idle not doing retransmits or persists 1044 * persisting to move a small or zero window 1045 * (re)transmitting and thereby not persisting 1046 * 1047 * tp->t_timer[TCPT_PERSIST] 1048 * is set when we are in persist state. 1049 * tp->t_force 1050 * is set when we are called to send a persist packet. 1051 * tp->t_timer[TCPT_REXMT] 1052 * is set when we are retransmitting 1053 * The output side is idle when both timers are zero. 1054 * 1055 * If send window is too small, there is data to transmit, and no 1056 * retransmit or persist is pending, then go to persist state. 1057 * If nothing happens soon, send when timer expires: 1058 * if window is nonzero, transmit what we can, 1059 * otherwise force out a byte. 1060 */ 1061 if (so->so_snd.sb_cc && TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 && 1062 TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) { 1063 tp->t_rxtshift = 0; 1064 tcp_setpersist(tp); 1065 } 1066 1067 /* 1068 * No reason to send a segment, just return. 1069 */ 1070 just_return: 1071 TCP_REASS_UNLOCK(tp); 1072 return 0; 1073 1074 send: 1075 /* 1076 * Before ESTABLISHED, force sending of initial options 1077 * unless TCP set not to do any options. 1078 * NOTE: we assume that the IP/TCP header plus TCP options 1079 * always fit in a single mbuf, leaving room for a maximum 1080 * link header, i.e. 1081 * max_linkhdr + sizeof (struct tcpiphdr) + optlen <= MCLBYTES 1082 */ 1083 optlen = 0; 1084 optp = opt; 1085 switch (af) { 1086 case AF_INET: 1087 iphdrlen = sizeof(struct ip) + sizeof(struct tcphdr); 1088 break; 1089 #ifdef INET6 1090 case AF_INET6: 1091 iphdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 1092 break; 1093 #endif 1094 default: /*pacify gcc*/ 1095 iphdrlen = 0; 1096 break; 1097 } 1098 hdrlen = iphdrlen; 1099 if (flags & TH_SYN) { 1100 struct rtentry *synrt; 1101 1102 synrt = NULL; 1103 if (tp->t_inpcb) 1104 synrt = in_pcbrtentry(tp->t_inpcb); 1105 #ifdef INET6 1106 if (tp->t_in6pcb) 1107 synrt = in6_pcbrtentry(tp->t_in6pcb); 1108 #endif 1109 1110 tp->snd_nxt = tp->iss; 1111 tp->t_ourmss = tcp_mss_to_advertise(synrt != NULL ? 1112 synrt->rt_ifp : NULL, af); 1113 if (tp->t_inpcb) 1114 in_pcbrtentry_unref(synrt, tp->t_inpcb); 1115 #ifdef INET6 1116 if (tp->t_in6pcb) 1117 in6_pcbrtentry_unref(synrt, tp->t_in6pcb); 1118 #endif 1119 if ((tp->t_flags & TF_NOOPT) == 0 && OPT_FITS(TCPOLEN_MAXSEG)) { 1120 *optp++ = TCPOPT_MAXSEG; 1121 *optp++ = TCPOLEN_MAXSEG; 1122 *optp++ = (tp->t_ourmss >> 8) & 0xff; 1123 *optp++ = tp->t_ourmss & 0xff; 1124 optlen += TCPOLEN_MAXSEG; 1125 1126 if ((tp->t_flags & TF_REQ_SCALE) && 1127 ((flags & TH_ACK) == 0 || 1128 (tp->t_flags & TF_RCVD_SCALE)) && 1129 OPT_FITS(TCPOLEN_WINDOW + TCPOLEN_NOP)) { 1130 *((uint32_t *)optp) = htonl( 1131 TCPOPT_NOP << 24 | 1132 TCPOPT_WINDOW << 16 | 1133 TCPOLEN_WINDOW << 8 | 1134 tp->request_r_scale); 1135 optp += TCPOLEN_WINDOW + TCPOLEN_NOP; 1136 optlen += TCPOLEN_WINDOW + TCPOLEN_NOP; 1137 } 1138 if (tcp_do_sack && OPT_FITS(TCPOLEN_SACK_PERMITTED)) { 1139 *optp++ = TCPOPT_SACK_PERMITTED; 1140 *optp++ = TCPOLEN_SACK_PERMITTED; 1141 optlen += TCPOLEN_SACK_PERMITTED; 1142 } 1143 } 1144 } 1145 1146 /* 1147 * Send a timestamp and echo-reply if this is a SYN and our side 1148 * wants to use timestamps (TF_REQ_TSTMP is set) or both our side 1149 * and our peer have sent timestamps in our SYN's. 1150 */ 1151 if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP && 1152 (flags & TH_RST) == 0 && 1153 ((flags & (TH_SYN|TH_ACK)) == TH_SYN || 1154 (tp->t_flags & TF_RCVD_TSTMP))) { 1155 int alen = 0; 1156 while (optlen % 4 != 2) { 1157 optlen += TCPOLEN_NOP; 1158 *optp++ = TCPOPT_NOP; 1159 alen++; 1160 } 1161 if (OPT_FITS(TCPOLEN_TIMESTAMP)) { 1162 *optp++ = TCPOPT_TIMESTAMP; 1163 *optp++ = TCPOLEN_TIMESTAMP; 1164 uint32_t *lp = (uint32_t *)optp; 1165 /* Form timestamp option (appendix A of RFC 1323) */ 1166 *lp++ = htonl(TCP_TIMESTAMP(tp)); 1167 *lp = htonl(tp->ts_recent); 1168 optp += TCPOLEN_TIMESTAMP - 2; 1169 optlen += TCPOLEN_TIMESTAMP; 1170 1171 /* Set receive buffer autosizing timestamp. */ 1172 if (tp->rfbuf_ts == 0 && 1173 (so->so_rcv.sb_flags & SB_AUTOSIZE)) 1174 tp->rfbuf_ts = TCP_TIMESTAMP(tp); 1175 } else { 1176 optp -= alen; 1177 optlen -= alen; 1178 } 1179 } 1180 1181 #ifdef TCP_SIGNATURE 1182 if (tp->t_flags & TF_SIGNATURE) { 1183 /* 1184 * Initialize TCP-MD5 option (RFC2385) 1185 */ 1186 if (!OPT_FITS(TCPOLEN_SIGNATURE)) 1187 goto reset; 1188 1189 *optp++ = TCPOPT_SIGNATURE; 1190 *optp++ = TCPOLEN_SIGNATURE; 1191 sigoff = optlen + 2; 1192 memset(optp, 0, TCP_SIGLEN); 1193 optlen += TCPOLEN_SIGNATURE; 1194 optp += TCP_SIGLEN; 1195 } 1196 #endif 1197 1198 /* 1199 * Tack on the SACK block if it is necessary. 1200 */ 1201 if (sack_numblks) { 1202 int alen = 0; 1203 int sack_len = sack_numblks * 8; 1204 while (optlen % 4 != 2) { 1205 optlen += TCPOLEN_NOP; 1206 *optp++ = TCPOPT_NOP; 1207 alen++; 1208 } 1209 if (OPT_FITS(sack_len + 2)) { 1210 struct ipqent *tiqe; 1211 *optp++ = TCPOPT_SACK; 1212 *optp++ = sack_len + 2; 1213 uint32_t *lp = (uint32_t *)optp; 1214 if ((tp->rcv_sack_flags & TCPSACK_HAVED) != 0) { 1215 sack_numblks--; 1216 *lp++ = htonl(tp->rcv_dsack_block.left); 1217 *lp++ = htonl(tp->rcv_dsack_block.right); 1218 tp->rcv_sack_flags &= ~TCPSACK_HAVED; 1219 } 1220 for (tiqe = TAILQ_FIRST(&tp->timeq); 1221 sack_numblks > 0; 1222 tiqe = TAILQ_NEXT(tiqe, ipqe_timeq)) { 1223 KASSERT(tiqe != NULL); 1224 sack_numblks--; 1225 *lp++ = htonl(tiqe->ipqe_seq); 1226 *lp++ = htonl(tiqe->ipqe_seq + tiqe->ipqe_len + 1227 ((tiqe->ipqe_flags & TH_FIN) != 0 ? 1 : 0)); 1228 } 1229 optlen += sack_len + 2; 1230 optp += sack_len; 1231 } else { 1232 optp -= alen; 1233 optlen -= alen; 1234 } 1235 } 1236 1237 /* Terminate and pad TCP options to a 4 byte boundary. */ 1238 if (optlen % 4) { 1239 if (!OPT_FITS(TCPOLEN_EOL)) { 1240 reset: TCP_REASS_UNLOCK(tp); 1241 error = ECONNABORTED; 1242 goto out; 1243 } 1244 optlen += TCPOLEN_EOL; 1245 *optp++ = TCPOPT_EOL; 1246 } 1247 /* 1248 * According to RFC 793 (STD0007): 1249 * "The content of the header beyond the End-of-Option option 1250 * must be header padding (i.e., zero)." 1251 * and later: "The padding is composed of zeros." 1252 */ 1253 while (optlen % 4) { 1254 if (!OPT_FITS(TCPOLEN_PAD)) 1255 goto reset; 1256 optlen += TCPOLEN_PAD; 1257 *optp++ = TCPOPT_PAD; 1258 } 1259 1260 TCP_REASS_UNLOCK(tp); 1261 1262 hdrlen += optlen; 1263 1264 #ifdef DIAGNOSTIC 1265 if (!use_tso && len > txsegsize) 1266 panic("tcp data to be sent is larger than segment"); 1267 else if (use_tso && len > IP_MAXPACKET) 1268 panic("tcp data to be sent is larger than max TSO size"); 1269 if (max_linkhdr + hdrlen > MCLBYTES) 1270 panic("tcphdr too big"); 1271 #endif 1272 1273 /* 1274 * Grab a header mbuf, attaching a copy of data to 1275 * be transmitted, and initialize the header from 1276 * the template for sends on this connection. 1277 */ 1278 if (len) { 1279 error = tcp_build_datapkt(tp, so, off, len, hdrlen, &m); 1280 if (error) 1281 goto out; 1282 /* 1283 * If we're sending everything we've got, set PUSH. 1284 * (This will keep happy those implementations which only 1285 * give data to the user when a buffer fills or 1286 * a PUSH comes in.) 1287 */ 1288 if (off + len == so->so_snd.sb_cc) 1289 flags |= TH_PUSH; 1290 } else { 1291 tcps = TCP_STAT_GETREF(); 1292 if (tp->t_flags & TF_ACKNOW) 1293 tcps[TCP_STAT_SNDACKS]++; 1294 else if (flags & (TH_SYN|TH_FIN|TH_RST)) 1295 tcps[TCP_STAT_SNDCTRL]++; 1296 else if (SEQ_GT(tp->snd_up, tp->snd_una)) 1297 tcps[TCP_STAT_SNDURG]++; 1298 else 1299 tcps[TCP_STAT_SNDWINUP]++; 1300 TCP_STAT_PUTREF(); 1301 1302 MGETHDR(m, M_DONTWAIT, MT_HEADER); 1303 if (m != NULL && max_linkhdr + hdrlen > MHLEN) { 1304 MCLGET(m, M_DONTWAIT); 1305 if ((m->m_flags & M_EXT) == 0) { 1306 m_freem(m); 1307 m = NULL; 1308 } 1309 } 1310 if (m == NULL) { 1311 error = ENOBUFS; 1312 goto out; 1313 } 1314 MCLAIM(m, &tcp_tx_mowner); 1315 m->m_data += max_linkhdr; 1316 m->m_len = hdrlen; 1317 } 1318 m_reset_rcvif(m); 1319 switch (af) { 1320 case AF_INET: 1321 ip = mtod(m, struct ip *); 1322 #ifdef INET6 1323 ip6 = NULL; 1324 #endif 1325 th = (struct tcphdr *)(ip + 1); 1326 break; 1327 #ifdef INET6 1328 case AF_INET6: 1329 ip = NULL; 1330 ip6 = mtod(m, struct ip6_hdr *); 1331 th = (struct tcphdr *)(ip6 + 1); 1332 break; 1333 #endif 1334 default: /*pacify gcc*/ 1335 ip = NULL; 1336 #ifdef INET6 1337 ip6 = NULL; 1338 #endif 1339 th = NULL; 1340 break; 1341 } 1342 if (tp->t_template == NULL) 1343 panic("tcp_output"); 1344 if (tp->t_template->m_len < iphdrlen) 1345 panic("tcp_output"); 1346 bcopy(mtod(tp->t_template, void *), mtod(m, void *), iphdrlen); 1347 1348 /* 1349 * If we are starting a connection, send ECN setup 1350 * SYN packet. If we are on a retransmit, we may 1351 * resend those bits a number of times as per 1352 * RFC 3168. 1353 */ 1354 if (tp->t_state == TCPS_SYN_SENT && tcp_do_ecn) { 1355 if (tp->t_flags & TF_SYN_REXMT) { 1356 if (tp->t_ecn_retries--) 1357 flags |= TH_ECE|TH_CWR; 1358 } else { 1359 flags |= TH_ECE|TH_CWR; 1360 tp->t_ecn_retries = tcp_ecn_maxretries; 1361 } 1362 } 1363 1364 if (TCP_ECN_ALLOWED(tp)) { 1365 /* 1366 * If the peer has ECN, mark data packets 1367 * ECN capable. Ignore pure ack packets, retransmissions 1368 * and window probes. 1369 */ 1370 if (len > 0 && SEQ_GEQ(tp->snd_nxt, tp->snd_max) && 1371 !(tp->t_force && len == 1)) { 1372 ecn_tos = IPTOS_ECN_ECT0; 1373 TCP_STATINC(TCP_STAT_ECN_ECT); 1374 } 1375 1376 /* 1377 * Reply with proper ECN notifications. 1378 */ 1379 if (tp->t_flags & TF_ECN_SND_CWR) { 1380 flags |= TH_CWR; 1381 tp->t_flags &= ~TF_ECN_SND_CWR; 1382 } 1383 if (tp->t_flags & TF_ECN_SND_ECE) { 1384 flags |= TH_ECE; 1385 } 1386 } 1387 1388 /* 1389 * If we are doing retransmissions, then snd_nxt will 1390 * not reflect the first unsent octet. For ACK only 1391 * packets, we do not want the sequence number of the 1392 * retransmitted packet, we want the sequence number 1393 * of the next unsent octet. So, if there is no data 1394 * (and no SYN or FIN), use snd_max instead of snd_nxt 1395 * when filling in ti_seq. But if we are in persist 1396 * state, snd_max might reflect one byte beyond the 1397 * right edge of the window, so use snd_nxt in that 1398 * case, since we know we aren't doing a retransmission. 1399 * (retransmit and persist are mutually exclusive...) 1400 */ 1401 if (TCP_SACK_ENABLED(tp) && sack_rxmit) { 1402 th->th_seq = htonl(p->rxmit); 1403 p->rxmit += len; 1404 } else { 1405 if (len || (flags & (TH_SYN|TH_FIN)) || 1406 TCP_TIMER_ISARMED(tp, TCPT_PERSIST)) 1407 th->th_seq = htonl(tp->snd_nxt); 1408 else 1409 th->th_seq = htonl(tp->snd_max); 1410 } 1411 th->th_ack = htonl(tp->rcv_nxt); 1412 if (optlen) { 1413 bcopy((void *)opt, (void *)(th + 1), optlen); 1414 th->th_off = (sizeof (struct tcphdr) + optlen) >> 2; 1415 } 1416 th->th_flags = flags; 1417 /* 1418 * Calculate receive window. Don't shrink window, 1419 * but avoid silly window syndrome. 1420 */ 1421 if (win < (long)(so->so_rcv.sb_hiwat / 4) && win < (long)rxsegsize) 1422 win = 0; 1423 if (win > (long)TCP_MAXWIN << tp->rcv_scale) 1424 win = (long)TCP_MAXWIN << tp->rcv_scale; 1425 if (win < (long)(int32_t)(tp->rcv_adv - tp->rcv_nxt)) 1426 win = (long)(int32_t)(tp->rcv_adv - tp->rcv_nxt); 1427 th->th_win = htons((u_int16_t) (win>>tp->rcv_scale)); 1428 if (th->th_win == 0) { 1429 tp->t_sndzerowin++; 1430 } 1431 if (SEQ_GT(tp->snd_up, tp->snd_nxt)) { 1432 u_int32_t urp = tp->snd_up - tp->snd_nxt; 1433 if (urp > IP_MAXPACKET) 1434 urp = IP_MAXPACKET; 1435 th->th_urp = htons((u_int16_t)urp); 1436 th->th_flags |= TH_URG; 1437 } else 1438 /* 1439 * If no urgent pointer to send, then we pull 1440 * the urgent pointer to the left edge of the send window 1441 * so that it doesn't drift into the send window on sequence 1442 * number wraparound. 1443 */ 1444 tp->snd_up = tp->snd_una; /* drag it along */ 1445 1446 #ifdef TCP_SIGNATURE 1447 if (sigoff && (tp->t_flags & TF_SIGNATURE)) { 1448 struct secasvar *sav; 1449 u_int8_t *sigp; 1450 1451 sav = tcp_signature_getsav(m); 1452 if (sav == NULL) { 1453 if (m) 1454 m_freem(m); 1455 return EPERM; 1456 } 1457 1458 m->m_pkthdr.len = hdrlen + len; 1459 sigp = (char *)th + sizeof(*th) + sigoff; 1460 tcp_signature(m, th, (char *)th - mtod(m, char *), sav, sigp); 1461 1462 key_sa_recordxfer(sav, m); 1463 KEY_SA_UNREF(&sav); 1464 } 1465 #endif 1466 1467 /* 1468 * Set ourselves up to be checksummed just before the packet 1469 * hits the wire. 1470 */ 1471 switch (af) { 1472 case AF_INET: 1473 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 1474 if (use_tso) { 1475 m->m_pkthdr.segsz = txsegsize; 1476 m->m_pkthdr.csum_flags = M_CSUM_TSOv4; 1477 } else { 1478 m->m_pkthdr.csum_flags = M_CSUM_TCPv4; 1479 if (len + optlen) { 1480 /* Fixup the pseudo-header checksum. */ 1481 /* XXXJRT Not IP Jumbogram safe. */ 1482 th->th_sum = in_cksum_addword(th->th_sum, 1483 htons((u_int16_t) (len + optlen))); 1484 } 1485 } 1486 break; 1487 #ifdef INET6 1488 case AF_INET6: 1489 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 1490 if (use_tso) { 1491 m->m_pkthdr.segsz = txsegsize; 1492 m->m_pkthdr.csum_flags = M_CSUM_TSOv6; 1493 } else { 1494 m->m_pkthdr.csum_flags = M_CSUM_TCPv6; 1495 if (len + optlen) { 1496 /* Fixup the pseudo-header checksum. */ 1497 /* XXXJRT: Not IPv6 Jumbogram safe. */ 1498 th->th_sum = in_cksum_addword(th->th_sum, 1499 htons((u_int16_t) (len + optlen))); 1500 } 1501 } 1502 break; 1503 #endif 1504 } 1505 1506 /* 1507 * In transmit state, time the transmission and arrange for 1508 * the retransmit. In persist state, just set snd_max. 1509 */ 1510 if (tp->t_force == 0 || TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) { 1511 tcp_seq startseq = tp->snd_nxt; 1512 1513 /* 1514 * Advance snd_nxt over sequence space of this segment. 1515 * There are no states in which we send both a SYN and a FIN, 1516 * so we collapse the tests for these flags. 1517 */ 1518 if (flags & (TH_SYN|TH_FIN)) 1519 tp->snd_nxt++; 1520 if (sack_rxmit) 1521 goto timer; 1522 tp->snd_nxt += len; 1523 if (SEQ_GT(tp->snd_nxt, tp->snd_max)) { 1524 tp->snd_max = tp->snd_nxt; 1525 /* 1526 * Time this transmission if not a retransmission and 1527 * not currently timing anything. 1528 */ 1529 if (tp->t_rtttime == 0) { 1530 tp->t_rtttime = tcp_now; 1531 tp->t_rtseq = startseq; 1532 TCP_STATINC(TCP_STAT_SEGSTIMED); 1533 } 1534 } 1535 1536 /* 1537 * Set retransmit timer if not currently set, 1538 * and not doing an ack or a keep-alive probe. 1539 * Initial value for retransmit timer is smoothed 1540 * round-trip time + 2 * round-trip time variance. 1541 * Initialize shift counter which is used for backoff 1542 * of retransmit time. 1543 */ 1544 timer: 1545 if (TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0) { 1546 if ((sack_rxmit && tp->snd_nxt != tp->snd_max) 1547 || tp->snd_nxt != tp->snd_una) { 1548 if (TCP_TIMER_ISARMED(tp, TCPT_PERSIST)) { 1549 TCP_TIMER_DISARM(tp, TCPT_PERSIST); 1550 tp->t_rxtshift = 0; 1551 } 1552 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 1553 } else if (len == 0 && so->so_snd.sb_cc > 0 1554 && TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) { 1555 /* 1556 * If we are sending a window probe and there's 1557 * unacked data in the socket, make sure at 1558 * least the persist timer is running. 1559 */ 1560 tp->t_rxtshift = 0; 1561 tcp_setpersist(tp); 1562 } 1563 } 1564 } else 1565 if (SEQ_GT(tp->snd_nxt + len, tp->snd_max)) 1566 tp->snd_max = tp->snd_nxt + len; 1567 1568 #ifdef TCP_DEBUG 1569 /* 1570 * Trace. 1571 */ 1572 if (so->so_options & SO_DEBUG) 1573 tcp_trace(TA_OUTPUT, tp->t_state, tp, m, 0); 1574 #endif 1575 1576 /* 1577 * Fill in IP length and desired time to live and 1578 * send to IP level. There should be a better way 1579 * to handle ttl and tos; we could keep them in 1580 * the template, but need a way to checksum without them. 1581 */ 1582 m->m_pkthdr.len = hdrlen + len; 1583 1584 switch (af) { 1585 case AF_INET: 1586 ip->ip_len = htons(m->m_pkthdr.len); 1587 packetlen = m->m_pkthdr.len; 1588 if (tp->t_inpcb) { 1589 ip->ip_ttl = tp->t_inpcb->inp_ip.ip_ttl; 1590 ip->ip_tos = tp->t_inpcb->inp_ip.ip_tos | ecn_tos; 1591 } 1592 #ifdef INET6 1593 else if (tp->t_in6pcb) { 1594 ip->ip_ttl = in6_selecthlim(tp->t_in6pcb, NULL); /*XXX*/ 1595 ip->ip_tos = ecn_tos; /*XXX*/ 1596 } 1597 #endif 1598 break; 1599 #ifdef INET6 1600 case AF_INET6: 1601 packetlen = m->m_pkthdr.len; 1602 ip6->ip6_nxt = IPPROTO_TCP; 1603 if (tp->t_in6pcb) { 1604 /* 1605 * we separately set hoplimit for every segment, since 1606 * the user might want to change the value via 1607 * setsockopt. Also, desired default hop limit might 1608 * be changed via Neighbor Discovery. 1609 */ 1610 ip6->ip6_hlim = in6_selecthlim_rt(tp->t_in6pcb); 1611 } 1612 ip6->ip6_flow |= htonl(ecn_tos << 20); 1613 /* ip6->ip6_flow = ??? (from template) */ 1614 /* ip6_plen will be filled in ip6_output(). */ 1615 break; 1616 #endif 1617 default: /*pacify gcc*/ 1618 packetlen = 0; 1619 break; 1620 } 1621 1622 switch (af) { 1623 case AF_INET: 1624 { 1625 struct mbuf *opts; 1626 1627 if (tp->t_inpcb) 1628 opts = tp->t_inpcb->inp_options; 1629 else 1630 opts = NULL; 1631 error = ip_output(m, opts, ro, 1632 (tp->t_mtudisc ? IP_MTUDISC : 0) | 1633 (so->so_options & SO_DONTROUTE), NULL, tp->t_inpcb); 1634 break; 1635 } 1636 #ifdef INET6 1637 case AF_INET6: 1638 { 1639 struct ip6_pktopts *opts; 1640 1641 if (tp->t_in6pcb) 1642 opts = tp->t_in6pcb->in6p_outputopts; 1643 else 1644 opts = NULL; 1645 error = ip6_output(m, opts, ro, so->so_options & SO_DONTROUTE, 1646 NULL, tp->t_in6pcb, NULL); 1647 break; 1648 } 1649 #endif 1650 default: 1651 error = EAFNOSUPPORT; 1652 break; 1653 } 1654 if (error) { 1655 out: 1656 if (error == ENOBUFS) { 1657 TCP_STATINC(TCP_STAT_SELFQUENCH); 1658 if (tp->t_inpcb) 1659 tcp_quench(tp->t_inpcb, 0); 1660 #ifdef INET6 1661 if (tp->t_in6pcb) 1662 tcp6_quench(tp->t_in6pcb, 0); 1663 #endif 1664 error = 0; 1665 } else if ((error == EHOSTUNREACH || error == ENETDOWN) && 1666 TCPS_HAVERCVDSYN(tp->t_state)) { 1667 tp->t_softerror = error; 1668 error = 0; 1669 } 1670 1671 /* Back out the sequence number advance. */ 1672 if (sack_rxmit) 1673 p->rxmit -= len; 1674 1675 /* Restart the delayed ACK timer, if necessary. */ 1676 if (tp->t_flags & TF_DELACK) 1677 TCP_RESTART_DELACK(tp); 1678 1679 return error; 1680 } 1681 1682 if (packetlen > tp->t_pmtud_mtu_sent) 1683 tp->t_pmtud_mtu_sent = packetlen; 1684 1685 tcps = TCP_STAT_GETREF(); 1686 tcps[TCP_STAT_SNDTOTAL]++; 1687 if (tp->t_flags & TF_DELACK) 1688 tcps[TCP_STAT_DELACK]++; 1689 TCP_STAT_PUTREF(); 1690 1691 /* 1692 * Data sent (as far as we can tell). 1693 * If this advertises a larger window than any other segment, 1694 * then remember the size of the advertised window. 1695 * Any pending ACK has now been sent. 1696 */ 1697 if (win > 0 && SEQ_GT(tp->rcv_nxt+win, tp->rcv_adv)) 1698 tp->rcv_adv = tp->rcv_nxt + win; 1699 tp->last_ack_sent = tp->rcv_nxt; 1700 tp->t_flags &= ~TF_ACKNOW; 1701 TCP_CLEAR_DELACK(tp); 1702 #ifdef DIAGNOSTIC 1703 if (maxburst < 0) 1704 printf("tcp_output: maxburst exceeded by %d\n", -maxburst); 1705 #endif 1706 if (sendalot && (tp->t_congctl == &tcp_reno_ctl || --maxburst)) 1707 goto again; 1708 return 0; 1709 } 1710 1711 void 1712 tcp_setpersist(struct tcpcb *tp) 1713 { 1714 int t = ((tp->t_srtt >> 2) + tp->t_rttvar) >> (1 + 2); 1715 int nticks; 1716 1717 if (TCP_TIMER_ISARMED(tp, TCPT_REXMT)) 1718 panic("tcp_output REXMT"); 1719 /* 1720 * Start/restart persistance timer. 1721 */ 1722 if (t < tp->t_rttmin) 1723 t = tp->t_rttmin; 1724 TCPT_RANGESET(nticks, t * tcp_backoff[tp->t_rxtshift], 1725 TCPTV_PERSMIN, TCPTV_PERSMAX); 1726 TCP_TIMER_ARM(tp, TCPT_PERSIST, nticks); 1727 if (tp->t_rxtshift < TCP_MAXRXTSHIFT) 1728 tp->t_rxtshift++; 1729 } 1730
Indexes created Tue Sep 23 14:10:03 GMT 2025