1 /* $NetBSD: tcp_output.c,v 1.131 2005/04/18 21:55:06 yamt 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 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 * 82 * Redistribution and use in source and binary forms, with or without 83 * modification, are permitted provided that the following conditions 84 * are met: 85 * 1. Redistributions of source code must retain the above copyright 86 * notice, this list of conditions and the following disclaimer. 87 * 2. Redistributions in binary form must reproduce the above copyright 88 * notice, this list of conditions and the following disclaimer in the 89 * documentation and/or other materials provided with the distribution. 90 * 3. All advertising materials mentioning features or use of this software 91 * must display the following acknowledgement: 92 * This product includes software developed by the NetBSD 93 * Foundation, Inc. and its contributors. 94 * 4. Neither the name of The NetBSD Foundation nor the names of its 95 * contributors may be used to endorse or promote products derived 96 * from this software without specific prior written permission. 97 * 98 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 99 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 100 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 101 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 102 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 103 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 104 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 105 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 106 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 107 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 108 * POSSIBILITY OF SUCH DAMAGE. 109 */ 110 111 /* 112 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995 113 * The Regents of the University of California. All rights reserved. 114 * 115 * Redistribution and use in source and binary forms, with or without 116 * modification, are permitted provided that the following conditions 117 * are met: 118 * 1. Redistributions of source code must retain the above copyright 119 * notice, this list of conditions and the following disclaimer. 120 * 2. Redistributions in binary form must reproduce the above copyright 121 * notice, this list of conditions and the following disclaimer in the 122 * documentation and/or other materials provided with the distribution. 123 * 3. Neither the name of the University nor the names of its contributors 124 * may be used to endorse or promote products derived from this software 125 * without specific prior written permission. 126 * 127 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 128 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 129 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 130 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 131 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 132 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 133 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 134 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 135 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 136 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 137 * SUCH DAMAGE. 138 * 139 * @(#)tcp_output.c 8.4 (Berkeley) 5/24/95 140 */ 141 142 #include <sys/cdefs.h> 143 __KERNEL_RCSID(0, "$NetBSD: tcp_output.c,v 1.131 2005/04/18 21:55:06 yamt Exp $"); 144 145 #include "opt_inet.h" 146 #include "opt_ipsec.h" 147 #include "opt_tcp_debug.h" 148 149 #include <sys/param.h> 150 #include <sys/systm.h> 151 #include <sys/malloc.h> 152 #include <sys/mbuf.h> 153 #include <sys/protosw.h> 154 #include <sys/socket.h> 155 #include <sys/socketvar.h> 156 #include <sys/errno.h> 157 #include <sys/domain.h> 158 #include <sys/kernel.h> 159 #ifdef TCP_SIGNATURE 160 #include <sys/md5.h> 161 #endif 162 163 #include <net/if.h> 164 #include <net/route.h> 165 166 #include <netinet/in.h> 167 #include <netinet/in_systm.h> 168 #include <netinet/ip.h> 169 #include <netinet/in_pcb.h> 170 #include <netinet/ip_var.h> 171 172 #ifdef INET6 173 #ifndef INET 174 #include <netinet/in.h> 175 #endif 176 #include <netinet/ip6.h> 177 #include <netinet6/in6_var.h> 178 #include <netinet6/ip6_var.h> 179 #include <netinet6/in6_pcb.h> 180 #include <netinet6/nd6.h> 181 #endif 182 183 #ifdef FAST_IPSEC 184 #include <netipsec/ipsec.h> 185 #include <netipsec/key.h> 186 #endif /* FAST_IPSEC*/ 187 #ifdef IPSEC 188 #include <netinet6/ipsec.h> 189 #endif 190 191 #include <netinet/tcp.h> 192 #define TCPOUTFLAGS 193 #include <netinet/tcp_fsm.h> 194 #include <netinet/tcp_seq.h> 195 #include <netinet/tcp_timer.h> 196 #include <netinet/tcp_var.h> 197 #include <netinet/tcpip.h> 198 #include <netinet/tcp_debug.h> 199 #include <netinet/in_offload.h> 200 201 #ifdef IPSEC 202 #include <netkey/key.h> 203 #endif 204 205 #ifdef notyet 206 extern struct mbuf *m_copypack(); 207 #endif 208 209 /* 210 * Knob to enable Congestion Window Monitoring, and control the 211 * the burst size it allows. Default burst is 4 packets, per 212 * the Internet draft. 213 */ 214 int tcp_cwm = 0; 215 int tcp_cwm_burstsize = 4; 216 217 #ifdef TCP_OUTPUT_COUNTERS 218 #include <sys/device.h> 219 220 extern struct evcnt tcp_output_bigheader; 221 extern struct evcnt tcp_output_predict_hit; 222 extern struct evcnt tcp_output_predict_miss; 223 extern struct evcnt tcp_output_copysmall; 224 extern struct evcnt tcp_output_copybig; 225 extern struct evcnt tcp_output_refbig; 226 227 #define TCP_OUTPUT_COUNTER_INCR(ev) (ev)->ev_count++ 228 #else 229 230 #define TCP_OUTPUT_COUNTER_INCR(ev) /* nothing */ 231 232 #endif /* TCP_OUTPUT_COUNTERS */ 233 234 static 235 #ifndef GPROF 236 __inline 237 #endif 238 int 239 tcp_segsize(struct tcpcb *tp, int *txsegsizep, int *rxsegsizep) 240 { 241 #ifdef INET 242 struct inpcb *inp = tp->t_inpcb; 243 #endif 244 #ifdef INET6 245 struct in6pcb *in6p = tp->t_in6pcb; 246 #endif 247 struct socket *so = NULL; 248 struct rtentry *rt; 249 struct ifnet *ifp; 250 int size; 251 int iphlen; 252 int optlen; 253 254 #ifdef DIAGNOSTIC 255 if (tp->t_inpcb && tp->t_in6pcb) 256 panic("tcp_segsize: both t_inpcb and t_in6pcb are set"); 257 #endif 258 switch (tp->t_family) { 259 #ifdef INET 260 case AF_INET: 261 iphlen = sizeof(struct ip); 262 break; 263 #endif 264 #ifdef INET6 265 case AF_INET6: 266 iphlen = sizeof(struct ip6_hdr); 267 break; 268 #endif 269 default: 270 size = tcp_mssdflt; 271 goto out; 272 } 273 274 rt = NULL; 275 #ifdef INET 276 if (inp) { 277 rt = in_pcbrtentry(inp); 278 so = inp->inp_socket; 279 } 280 #endif 281 #ifdef INET6 282 if (in6p) { 283 rt = in6_pcbrtentry(in6p); 284 so = in6p->in6p_socket; 285 } 286 #endif 287 if (rt == NULL) { 288 size = tcp_mssdflt; 289 goto out; 290 } 291 292 ifp = rt->rt_ifp; 293 294 size = tcp_mssdflt; 295 if (tp->t_mtudisc && rt->rt_rmx.rmx_mtu != 0) { 296 #ifdef INET6 297 if (in6p && rt->rt_rmx.rmx_mtu < IPV6_MMTU) { 298 /* 299 * RFC2460 section 5, last paragraph: if path MTU is 300 * smaller than 1280, use 1280 as packet size and 301 * attach fragment header. 302 */ 303 size = IPV6_MMTU - iphlen - sizeof(struct ip6_frag) - 304 sizeof(struct tcphdr); 305 } else 306 size = rt->rt_rmx.rmx_mtu - iphlen - 307 sizeof(struct tcphdr); 308 #else 309 size = rt->rt_rmx.rmx_mtu - iphlen - sizeof(struct tcphdr); 310 #endif 311 } else if (ifp->if_flags & IFF_LOOPBACK) 312 size = ifp->if_mtu - iphlen - sizeof(struct tcphdr); 313 #ifdef INET 314 else if (inp && tp->t_mtudisc) 315 size = ifp->if_mtu - iphlen - sizeof(struct tcphdr); 316 else if (inp && in_localaddr(inp->inp_faddr)) 317 size = ifp->if_mtu - iphlen - sizeof(struct tcphdr); 318 #endif 319 #ifdef INET6 320 else if (in6p) { 321 #ifdef INET 322 if (IN6_IS_ADDR_V4MAPPED(&in6p->in6p_faddr)) { 323 /* mapped addr case */ 324 struct in_addr d; 325 bcopy(&in6p->in6p_faddr.s6_addr32[3], &d, sizeof(d)); 326 if (tp->t_mtudisc || in_localaddr(d)) 327 size = ifp->if_mtu - iphlen - sizeof(struct tcphdr); 328 } else 329 #endif 330 { 331 /* 332 * for IPv6, path MTU discovery is always turned on, 333 * or the node must use packet size <= 1280. 334 */ 335 size = tp->t_mtudisc ? IN6_LINKMTU(ifp) : IPV6_MMTU; 336 size -= (iphlen + sizeof(struct tcphdr)); 337 } 338 } 339 #endif 340 out: 341 /* 342 * Now we must make room for whatever extra TCP/IP options are in 343 * the packet. 344 */ 345 optlen = tcp_optlen(tp); 346 347 /* 348 * XXX tp->t_ourmss should have the right size, but without this code 349 * fragmentation will occur... need more investigation 350 */ 351 #ifdef INET 352 if (inp) { 353 #if defined(IPSEC) || defined(FAST_IPSEC) 354 if (! IPSEC_PCB_SKIP_IPSEC(inp->inp_sp, IPSEC_DIR_OUTBOUND)) 355 optlen += ipsec4_hdrsiz_tcp(tp); 356 #endif 357 optlen += ip_optlen(inp); 358 } 359 #endif 360 #ifdef INET6 361 #ifdef INET 362 if (in6p && tp->t_family == AF_INET) { 363 #if defined(IPSEC) || defined(FAST_IPSEC) 364 if (! IPSEC_PCB_SKIP_IPSEC(in6p->in6p_sp, IPSEC_DIR_OUTBOUND)) 365 optlen += ipsec4_hdrsiz_tcp(tp); 366 #endif 367 /* XXX size -= ip_optlen(in6p); */ 368 } else 369 #endif 370 if (in6p && tp->t_family == AF_INET6) { 371 #ifdef IPSEC 372 if (! IPSEC_PCB_SKIP_IPSEC(in6p->in6p_sp, IPSEC_DIR_OUTBOUND)) 373 optlen += ipsec6_hdrsiz_tcp(tp); 374 #endif 375 optlen += ip6_optlen(in6p); 376 } 377 #endif 378 size -= optlen; 379 380 /* there may not be any room for data if mtu is too small */ 381 if (size < 0) 382 return (EMSGSIZE); 383 384 /* 385 * *rxsegsizep holds *estimated* inbound segment size (estimation 386 * assumes that path MTU is the same for both ways). this is only 387 * for silly window avoidance, do not use the value for other purposes. 388 * 389 * ipseclen is subtracted from both sides, this may not be right. 390 * I'm not quite sure about this (could someone comment). 391 */ 392 *txsegsizep = min(tp->t_peermss - optlen, size); 393 /* 394 * Never send more than half a buffer full. This insures that we can 395 * always keep 2 packets on the wire, no matter what SO_SNDBUF is, and 396 * therefore acks will never be delayed unless we run out of data to 397 * transmit. 398 */ 399 if (so) 400 *txsegsizep = min(so->so_snd.sb_hiwat >> 1, *txsegsizep); 401 *rxsegsizep = min(tp->t_ourmss - optlen, size); 402 403 if (*txsegsizep != tp->t_segsz) { 404 /* 405 * If the new segment size is larger, we don't want to 406 * mess up the congestion window, but if it is smaller 407 * we'll have to reduce the congestion window to ensure 408 * that we don't get into trouble with initial windows 409 * and the rest. In any case, if the segment size 410 * has changed, chances are the path has, too, and 411 * our congestion window will be different. 412 */ 413 if (*txsegsizep < tp->t_segsz) { 414 tp->snd_cwnd = max((tp->snd_cwnd / tp->t_segsz) 415 * *txsegsizep, *txsegsizep); 416 tp->snd_ssthresh = max((tp->snd_ssthresh / tp->t_segsz) 417 * *txsegsizep, *txsegsizep); 418 } 419 tp->t_segsz = *txsegsizep; 420 } 421 422 return (0); 423 } 424 425 static 426 #ifndef GPROF 427 __inline 428 #endif 429 int 430 tcp_build_datapkt(struct tcpcb *tp, struct socket *so, int off, 431 long len, int hdrlen, struct mbuf **mp) 432 { 433 struct mbuf *m, *m0; 434 435 if (tp->t_force && len == 1) 436 tcpstat.tcps_sndprobe++; 437 else if (SEQ_LT(tp->snd_nxt, tp->snd_max)) { 438 tcpstat.tcps_sndrexmitpack++; 439 tcpstat.tcps_sndrexmitbyte += len; 440 } else { 441 tcpstat.tcps_sndpack++; 442 tcpstat.tcps_sndbyte += len; 443 } 444 #ifdef notyet 445 if ((m = m_copypack(so->so_snd.sb_mb, off, 446 (int)len, max_linkhdr + hdrlen)) == 0) 447 return (ENOBUFS); 448 /* 449 * m_copypack left space for our hdr; use it. 450 */ 451 m->m_len += hdrlen; 452 m->m_data -= hdrlen; 453 #else 454 MGETHDR(m, M_DONTWAIT, MT_HEADER); 455 if (__predict_false(m == NULL)) 456 return (ENOBUFS); 457 MCLAIM(m, &tcp_tx_mowner); 458 459 /* 460 * XXX Because other code assumes headers will fit in 461 * XXX one header mbuf. 462 * 463 * (This code should almost *never* be run.) 464 */ 465 if (__predict_false((max_linkhdr + hdrlen) > MHLEN)) { 466 TCP_OUTPUT_COUNTER_INCR(&tcp_output_bigheader); 467 MCLGET(m, M_DONTWAIT); 468 if ((m->m_flags & M_EXT) == 0) { 469 m_freem(m); 470 return (ENOBUFS); 471 } 472 } 473 474 m->m_data += max_linkhdr; 475 m->m_len = hdrlen; 476 477 /* 478 * To avoid traversing the whole sb_mb chain for correct 479 * data to send, remember last sent mbuf, its offset and 480 * the sent size. When called the next time, see if the 481 * data to send is directly following the previous transfer. 482 * This is important for large TCP windows. 483 */ 484 if (off == 0 || tp->t_lastm == NULL || 485 (tp->t_lastoff + tp->t_lastlen) != off) { 486 TCP_OUTPUT_COUNTER_INCR(&tcp_output_predict_miss); 487 /* 488 * Either a new packet or a retransmit. 489 * Start from the beginning. 490 */ 491 tp->t_lastm = so->so_snd.sb_mb; 492 tp->t_inoff = off; 493 } else { 494 TCP_OUTPUT_COUNTER_INCR(&tcp_output_predict_hit); 495 tp->t_inoff += tp->t_lastlen; 496 } 497 498 /* Traverse forward to next packet */ 499 while (tp->t_inoff > 0) { 500 if (tp->t_lastm == NULL) 501 panic("tp->t_lastm == NULL"); 502 if (tp->t_inoff < tp->t_lastm->m_len) 503 break; 504 tp->t_inoff -= tp->t_lastm->m_len; 505 tp->t_lastm = tp->t_lastm->m_next; 506 } 507 508 tp->t_lastoff = off; 509 tp->t_lastlen = len; 510 m0 = tp->t_lastm; 511 off = tp->t_inoff; 512 513 if (len <= M_TRAILINGSPACE(m)) { 514 m_copydata(m0, off, (int) len, mtod(m, caddr_t) + hdrlen); 515 m->m_len += len; 516 TCP_OUTPUT_COUNTER_INCR(&tcp_output_copysmall); 517 } else { 518 m->m_next = m_copy(m0, off, (int) len); 519 if (m->m_next == NULL) { 520 m_freem(m); 521 return (ENOBUFS); 522 } 523 #ifdef TCP_OUTPUT_COUNTERS 524 if (m->m_next->m_flags & M_EXT) 525 TCP_OUTPUT_COUNTER_INCR(&tcp_output_refbig); 526 else 527 TCP_OUTPUT_COUNTER_INCR(&tcp_output_copybig); 528 #endif /* TCP_OUTPUT_COUNTERS */ 529 } 530 #endif 531 532 *mp = m; 533 return (0); 534 } 535 536 /* 537 * Tcp output routine: figure out what should be sent and send it. 538 */ 539 int 540 tcp_output(struct tcpcb *tp) 541 { 542 struct socket *so; 543 struct route *ro; 544 long len, win; 545 int off, flags, error; 546 struct mbuf *m; 547 struct ip *ip; 548 #ifdef INET6 549 struct ip6_hdr *ip6; 550 #endif 551 struct tcphdr *th; 552 u_char opt[MAX_TCPOPTLEN]; 553 unsigned optlen, hdrlen; 554 unsigned int sack_numblks; 555 int idle, sendalot, txsegsize, rxsegsize; 556 int txsegsize_nosack; 557 int maxburst = TCP_MAXBURST; 558 int af; /* address family on the wire */ 559 int iphdrlen; 560 int has_tso, use_tso; 561 int sack_rxmit; 562 int sack_bytes_rxmt; 563 struct sackhole *p; 564 #ifdef TCP_SIGNATURE 565 int sigoff = 0; 566 #endif 567 568 #ifdef DIAGNOSTIC 569 if (tp->t_inpcb && tp->t_in6pcb) 570 panic("tcp_output: both t_inpcb and t_in6pcb are set"); 571 #endif 572 so = NULL; 573 ro = NULL; 574 if (tp->t_inpcb) { 575 so = tp->t_inpcb->inp_socket; 576 ro = &tp->t_inpcb->inp_route; 577 } 578 #ifdef INET6 579 else if (tp->t_in6pcb) { 580 so = tp->t_in6pcb->in6p_socket; 581 ro = (struct route *)&tp->t_in6pcb->in6p_route; 582 } 583 #endif 584 585 switch (af = tp->t_family) { 586 #ifdef INET 587 case AF_INET: 588 if (tp->t_inpcb) 589 break; 590 #ifdef INET6 591 /* mapped addr case */ 592 if (tp->t_in6pcb) 593 break; 594 #endif 595 return (EINVAL); 596 #endif 597 #ifdef INET6 598 case AF_INET6: 599 if (tp->t_in6pcb) 600 break; 601 return (EINVAL); 602 #endif 603 default: 604 return (EAFNOSUPPORT); 605 } 606 607 if (tcp_segsize(tp, &txsegsize, &rxsegsize)) 608 return (EMSGSIZE); 609 610 idle = (tp->snd_max == tp->snd_una); 611 612 /* 613 * Determine if we can use TCP segmentation offload: 614 * - If we're using IPv4 615 * - If there is not an IPsec policy that prevents it 616 * - If the interface can do it 617 */ 618 has_tso = tp->t_inpcb != NULL && 619 #if defined(IPSEC) || defined(FAST_IPSEC) 620 IPSEC_PCB_SKIP_IPSEC(tp->t_inpcb->inp_sp, 621 IPSEC_DIR_OUTBOUND) && 622 #endif 623 tp->t_inpcb->inp_route.ro_rt != NULL && 624 (tp->t_inpcb->inp_route.ro_rt->rt_ifp->if_capenable & 625 IFCAP_TSOv4) != 0; 626 627 /* 628 * Restart Window computation. From draft-floyd-incr-init-win-03: 629 * 630 * Optionally, a TCP MAY set the restart window to the 631 * minimum of the value used for the initial window and 632 * the current value of cwnd (in other words, using a 633 * larger value for the restart window should never increase 634 * the size of cwnd). 635 */ 636 if (tcp_cwm) { 637 /* 638 * Hughes/Touch/Heidemann Congestion Window Monitoring. 639 * Count the number of packets currently pending 640 * acknowledgement, and limit our congestion window 641 * to a pre-determined allowed burst size plus that count. 642 * This prevents bursting once all pending packets have 643 * been acknowledged (i.e. transmission is idle). 644 * 645 * XXX Link this to Initial Window? 646 */ 647 tp->snd_cwnd = min(tp->snd_cwnd, 648 (tcp_cwm_burstsize * txsegsize) + 649 (tp->snd_nxt - tp->snd_una)); 650 } else { 651 if (idle && (tcp_now - tp->t_rcvtime) >= tp->t_rxtcur) { 652 /* 653 * We have been idle for "a while" and no acks are 654 * expected to clock out any data we send -- 655 * slow start to get ack "clock" running again. 656 */ 657 int ss = tcp_init_win; 658 #ifdef INET 659 if (tp->t_inpcb && 660 in_localaddr(tp->t_inpcb->inp_faddr)) 661 ss = tcp_init_win_local; 662 #endif 663 #ifdef INET6 664 if (tp->t_in6pcb && 665 in6_localaddr(&tp->t_in6pcb->in6p_faddr)) 666 ss = tcp_init_win_local; 667 #endif 668 tp->snd_cwnd = min(tp->snd_cwnd, 669 TCP_INITIAL_WINDOW(ss, txsegsize)); 670 } 671 } 672 673 txsegsize_nosack = txsegsize; 674 again: 675 use_tso = has_tso; 676 TCP_REASS_LOCK(tp); 677 sack_numblks = tcp_sack_numblks(tp); 678 if (sack_numblks) { 679 if ((tp->rcv_sack_flags & TCPSACK_HAVED) != 0) { 680 /* don't duplicate D-SACK. */ 681 use_tso = 0; 682 } 683 txsegsize = txsegsize_nosack - TCP_SACK_OPTLEN(sack_numblks); 684 } else { 685 txsegsize = txsegsize_nosack; 686 } 687 688 /* 689 * Determine length of data that should be transmitted, and 690 * flags that should be used. If there is some data or critical 691 * controls (SYN, RST) to send, then transmit; otherwise, 692 * investigate further. 693 * 694 * Readjust SACK information to avoid resending duplicate data. 695 */ 696 if (TCP_SACK_ENABLED(tp) && SEQ_LT(tp->snd_nxt, tp->snd_max)) 697 tcp_sack_adjust(tp); 698 sendalot = 0; 699 off = tp->snd_nxt - tp->snd_una; 700 win = min(tp->snd_wnd, tp->snd_cwnd); 701 702 flags = tcp_outflags[tp->t_state]; 703 704 /* 705 * Send any SACK-generated retransmissions. If we're explicitly trying 706 * to send out new data (when sendalot is 1), bypass this function. 707 * If we retransmit in fast recovery mode, decrement snd_cwnd, since 708 * we're replacing a (future) new transmission with a retransmission 709 * now, and we previously incremented snd_cwnd in tcp_input(). 710 */ 711 /* 712 * Still in sack recovery , reset rxmit flag to zero. 713 */ 714 sack_rxmit = 0; 715 sack_bytes_rxmt = 0; 716 len = 0; 717 p = NULL; 718 do { 719 long cwin; 720 if (!TCP_SACK_ENABLED(tp)) 721 break; 722 if (tp->t_partialacks < 0) 723 break; 724 p = tcp_sack_output(tp, &sack_bytes_rxmt); 725 if (p == NULL) 726 break; 727 728 cwin = min(tp->snd_wnd, tp->snd_cwnd) - sack_bytes_rxmt; 729 if (cwin < 0) 730 cwin = 0; 731 /* Do not retransmit SACK segments beyond snd_recover */ 732 if (SEQ_GT(p->end, tp->snd_recover)) { 733 /* 734 * (At least) part of sack hole extends beyond 735 * snd_recover. Check to see if we can rexmit data 736 * for this hole. 737 */ 738 if (SEQ_GEQ(p->rxmit, tp->snd_recover)) { 739 /* 740 * Can't rexmit any more data for this hole. 741 * That data will be rexmitted in the next 742 * sack recovery episode, when snd_recover 743 * moves past p->rxmit. 744 */ 745 p = NULL; 746 break; 747 } 748 /* Can rexmit part of the current hole */ 749 len = ((long)ulmin(cwin, tp->snd_recover - p->rxmit)); 750 } else 751 len = ((long)ulmin(cwin, p->end - p->rxmit)); 752 off = p->rxmit - tp->snd_una; 753 if (len > 0) { 754 sack_rxmit = 1; 755 sendalot = 1; 756 } 757 } while (/*CONSTCOND*/0); 758 759 /* 760 * If in persist timeout with window of 0, send 1 byte. 761 * Otherwise, if window is small but nonzero 762 * and timer expired, we will send what we can 763 * and go to transmit state. 764 */ 765 if (tp->t_force) { 766 if (win == 0) { 767 /* 768 * If we still have some data to send, then 769 * clear the FIN bit. Usually this would 770 * happen below when it realizes that we 771 * aren't sending all the data. However, 772 * if we have exactly 1 byte of unset data, 773 * then it won't clear the FIN bit below, 774 * and if we are in persist state, we wind 775 * up sending the packet without recording 776 * that we sent the FIN bit. 777 * 778 * We can't just blindly clear the FIN bit, 779 * because if we don't have any more data 780 * to send then the probe will be the FIN 781 * itself. 782 */ 783 if (off < so->so_snd.sb_cc) 784 flags &= ~TH_FIN; 785 win = 1; 786 } else { 787 TCP_TIMER_DISARM(tp, TCPT_PERSIST); 788 tp->t_rxtshift = 0; 789 } 790 } 791 792 if (!TCP_SACK_ENABLED(tp)) { 793 if (win < so->so_snd.sb_cc) { 794 len = win - off; 795 flags &= ~TH_FIN; 796 } else 797 len = so->so_snd.sb_cc - off; 798 } else if (sack_rxmit == 0) { 799 if (sack_bytes_rxmt != 0) { 800 long cwin; 801 802 /* 803 * We are inside of a SACK recovery episode and are 804 * sending new data, having retransmitted all the 805 * data possible in the scoreboard. 806 */ 807 len = ((long)ulmin(so->so_snd.sb_cc, tp->snd_wnd) 808 - off); 809 /* 810 * From FreeBSD: 811 * Don't remove this (len > 0) check ! 812 * We explicitly check for len > 0 here (although it 813 * isn't really necessary), to work around a gcc 814 * optimization issue - to force gcc to compute 815 * len above. Without this check, the computation 816 * of len is bungled by the optimizer. 817 */ 818 if (len > 0) { 819 cwin = tp->snd_cwnd - 820 (tp->snd_nxt - tp->sack_newdata) - 821 sack_bytes_rxmt; 822 if (cwin < 0) 823 cwin = 0; 824 len = lmin(len, cwin); 825 } 826 } else if (win < so->so_snd.sb_cc) { 827 len = win - off; 828 flags &= ~TH_FIN; 829 } else 830 len = so->so_snd.sb_cc - off; 831 } 832 833 if (len < 0) { 834 /* 835 * If FIN has been sent but not acked, 836 * but we haven't been called to retransmit, 837 * len will be -1. Otherwise, window shrank 838 * after we sent into it. If window shrank to 0, 839 * cancel pending retransmit, pull snd_nxt back 840 * to (closed) window, and set the persist timer 841 * if it isn't already going. If the window didn't 842 * close completely, just wait for an ACK. 843 * 844 * If we have a pending FIN, either it has already been 845 * transmitted or it is outside the window, so drop it. 846 * If the FIN has been transmitted, but this is not a 847 * retransmission, then len must be -1. Therefore we also 848 * prevent here the sending of `gratuitous FINs'. This 849 * eliminates the need to check for that case below (e.g. 850 * to back up snd_nxt before the FIN so that the sequence 851 * number is correct). 852 */ 853 len = 0; 854 flags &= ~TH_FIN; 855 if (win == 0) { 856 TCP_TIMER_DISARM(tp, TCPT_REXMT); 857 tp->t_rxtshift = 0; 858 tp->snd_nxt = tp->snd_una; 859 if (TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) 860 tcp_setpersist(tp); 861 } 862 } 863 if (len > txsegsize) { 864 if (use_tso) { 865 /* 866 * Truncate TSO transfers to IP_MAXPACKET, and make 867 * sure that we send equal size transfers down the 868 * stack (rather than big-small-big-small-...). 869 */ 870 len = (min(len, IP_MAXPACKET) / txsegsize) * txsegsize; 871 if (len <= txsegsize) { 872 use_tso = 0; 873 } 874 } else 875 len = txsegsize; 876 flags &= ~TH_FIN; 877 sendalot = 1; 878 } else 879 use_tso = 0; 880 if (sack_rxmit) { 881 if (SEQ_LT(p->rxmit + len, tp->snd_una + so->so_snd.sb_cc)) 882 flags &= ~TH_FIN; 883 } 884 885 win = sbspace(&so->so_rcv); 886 887 /* 888 * Sender silly window avoidance. If connection is idle 889 * and can send all data, a maximum segment, 890 * at least a maximum default-size segment do it, 891 * or are forced, do it; otherwise don't bother. 892 * If peer's buffer is tiny, then send 893 * when window is at least half open. 894 * If retransmitting (possibly after persist timer forced us 895 * to send into a small window), then must resend. 896 */ 897 if (len) { 898 if (len >= txsegsize) 899 goto send; 900 if ((so->so_state & SS_MORETOCOME) == 0 && 901 ((idle || tp->t_flags & TF_NODELAY) && 902 len + off >= so->so_snd.sb_cc)) 903 goto send; 904 if (tp->t_force) 905 goto send; 906 if (len >= tp->max_sndwnd / 2) 907 goto send; 908 if (SEQ_LT(tp->snd_nxt, tp->snd_max)) 909 goto send; 910 if (sack_rxmit) 911 goto send; 912 } 913 914 /* 915 * Compare available window to amount of window known to peer 916 * (as advertised window less next expected input). If the 917 * difference is at least twice the size of the largest segment 918 * we expect to receive (i.e. two segments) or at least 50% of 919 * the maximum possible window, then want to send a window update 920 * to peer. 921 */ 922 if (win > 0) { 923 /* 924 * "adv" is the amount we can increase the window, 925 * taking into account that we are limited by 926 * TCP_MAXWIN << tp->rcv_scale. 927 */ 928 long adv = min(win, (long)TCP_MAXWIN << tp->rcv_scale) - 929 (tp->rcv_adv - tp->rcv_nxt); 930 931 if (adv >= (long) (2 * rxsegsize)) 932 goto send; 933 if (2 * adv >= (long) so->so_rcv.sb_hiwat) 934 goto send; 935 } 936 937 /* 938 * Send if we owe peer an ACK. 939 */ 940 if (tp->t_flags & TF_ACKNOW) 941 goto send; 942 if (flags & (TH_SYN|TH_FIN|TH_RST)) 943 goto send; 944 if (SEQ_GT(tp->snd_up, tp->snd_una)) 945 goto send; 946 /* 947 * In SACK, it is possible for tcp_output to fail to send a segment 948 * after the retransmission timer has been turned off. Make sure 949 * that the retransmission timer is set. 950 */ 951 if (TCP_SACK_ENABLED(tp) && SEQ_GT(tp->snd_max, tp->snd_una) && 952 !TCP_TIMER_ISARMED(tp, TCPT_REXMT) && 953 !TCP_TIMER_ISARMED(tp, TCPT_PERSIST)) { 954 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 955 goto just_return; 956 } 957 958 /* 959 * TCP window updates are not reliable, rather a polling protocol 960 * using ``persist'' packets is used to insure receipt of window 961 * updates. The three ``states'' for the output side are: 962 * idle not doing retransmits or persists 963 * persisting to move a small or zero window 964 * (re)transmitting and thereby not persisting 965 * 966 * tp->t_timer[TCPT_PERSIST] 967 * is set when we are in persist state. 968 * tp->t_force 969 * is set when we are called to send a persist packet. 970 * tp->t_timer[TCPT_REXMT] 971 * is set when we are retransmitting 972 * The output side is idle when both timers are zero. 973 * 974 * If send window is too small, there is data to transmit, and no 975 * retransmit or persist is pending, then go to persist state. 976 * If nothing happens soon, send when timer expires: 977 * if window is nonzero, transmit what we can, 978 * otherwise force out a byte. 979 */ 980 if (so->so_snd.sb_cc && TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 && 981 TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) { 982 tp->t_rxtshift = 0; 983 tcp_setpersist(tp); 984 } 985 986 /* 987 * No reason to send a segment, just return. 988 */ 989 just_return: 990 TCP_REASS_UNLOCK(tp); 991 return (0); 992 993 send: 994 /* 995 * Before ESTABLISHED, force sending of initial options 996 * unless TCP set not to do any options. 997 * NOTE: we assume that the IP/TCP header plus TCP options 998 * always fit in a single mbuf, leaving room for a maximum 999 * link header, i.e. 1000 * max_linkhdr + sizeof (struct tcpiphdr) + optlen <= MCLBYTES 1001 */ 1002 optlen = 0; 1003 switch (af) { 1004 #ifdef INET 1005 case AF_INET: 1006 iphdrlen = sizeof(struct ip) + sizeof(struct tcphdr); 1007 break; 1008 #endif 1009 #ifdef INET6 1010 case AF_INET6: 1011 iphdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 1012 break; 1013 #endif 1014 default: /*pacify gcc*/ 1015 iphdrlen = 0; 1016 break; 1017 } 1018 hdrlen = iphdrlen; 1019 if (flags & TH_SYN) { 1020 struct rtentry *rt; 1021 1022 rt = NULL; 1023 #ifdef INET 1024 if (tp->t_inpcb) 1025 rt = in_pcbrtentry(tp->t_inpcb); 1026 #endif 1027 #ifdef INET6 1028 if (tp->t_in6pcb) 1029 rt = in6_pcbrtentry(tp->t_in6pcb); 1030 #endif 1031 1032 tp->snd_nxt = tp->iss; 1033 tp->t_ourmss = tcp_mss_to_advertise(rt != NULL ? 1034 rt->rt_ifp : NULL, af); 1035 if ((tp->t_flags & TF_NOOPT) == 0) { 1036 opt[0] = TCPOPT_MAXSEG; 1037 opt[1] = 4; 1038 opt[2] = (tp->t_ourmss >> 8) & 0xff; 1039 opt[3] = tp->t_ourmss & 0xff; 1040 optlen = 4; 1041 1042 if ((tp->t_flags & TF_REQ_SCALE) && 1043 ((flags & TH_ACK) == 0 || 1044 (tp->t_flags & TF_RCVD_SCALE))) { 1045 *((u_int32_t *) (opt + optlen)) = htonl( 1046 TCPOPT_NOP << 24 | 1047 TCPOPT_WINDOW << 16 | 1048 TCPOLEN_WINDOW << 8 | 1049 tp->request_r_scale); 1050 optlen += 4; 1051 } 1052 if (tcp_do_sack) { 1053 u_int8_t *p = (u_int8_t *)(opt + optlen); 1054 1055 p[0] = TCPOPT_SACK_PERMITTED; 1056 p[1] = 2; 1057 p[2] = TCPOPT_NOP; 1058 p[3] = TCPOPT_NOP; 1059 optlen += 4; 1060 } 1061 } 1062 } 1063 1064 /* 1065 * Send a timestamp and echo-reply if this is a SYN and our side 1066 * wants to use timestamps (TF_REQ_TSTMP is set) or both our side 1067 * and our peer have sent timestamps in our SYN's. 1068 */ 1069 if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP && 1070 (flags & TH_RST) == 0 && 1071 ((flags & (TH_SYN|TH_ACK)) == TH_SYN || 1072 (tp->t_flags & TF_RCVD_TSTMP))) { 1073 u_int32_t *lp = (u_int32_t *)(opt + optlen); 1074 1075 /* Form timestamp option as shown in appendix A of RFC 1323. */ 1076 *lp++ = htonl(TCPOPT_TSTAMP_HDR); 1077 *lp++ = htonl(TCP_TIMESTAMP(tp)); 1078 *lp = htonl(tp->ts_recent); 1079 optlen += TCPOLEN_TSTAMP_APPA; 1080 } 1081 1082 /* 1083 * Tack on the SACK block if it is necessary. 1084 */ 1085 if (sack_numblks) { 1086 int sack_len; 1087 u_char *bp = (u_char *)(opt + optlen); 1088 u_int32_t *lp = (u_int32_t *)(bp + 4); 1089 struct ipqent *tiqe; 1090 1091 sack_len = sack_numblks * 8 + 2; 1092 bp[0] = TCPOPT_NOP; 1093 bp[1] = TCPOPT_NOP; 1094 bp[2] = TCPOPT_SACK; 1095 bp[3] = sack_len; 1096 if ((tp->rcv_sack_flags & TCPSACK_HAVED) != 0) { 1097 sack_numblks--; 1098 *lp++ = htonl(tp->rcv_dsack_block.left); 1099 *lp++ = htonl(tp->rcv_dsack_block.right); 1100 tp->rcv_sack_flags &= ~TCPSACK_HAVED; 1101 } 1102 for (tiqe = TAILQ_FIRST(&tp->timeq); 1103 sack_numblks > 0; tiqe = TAILQ_NEXT(tiqe, ipqe_timeq)) { 1104 KASSERT(tiqe != NULL); 1105 sack_numblks--; 1106 *lp++ = htonl(tiqe->ipqe_seq); 1107 *lp++ = htonl(tiqe->ipqe_seq + tiqe->ipqe_len); 1108 } 1109 optlen += sack_len + 2; 1110 } 1111 TCP_REASS_UNLOCK(tp); 1112 1113 #ifdef TCP_SIGNATURE 1114 #if defined(INET6) && defined(FAST_IPSEC) 1115 if (tp->t_family == AF_INET) 1116 #endif 1117 if (tp->t_flags & TF_SIGNATURE) { 1118 u_char *bp; 1119 /* 1120 * Initialize TCP-MD5 option (RFC2385) 1121 */ 1122 bp = (u_char *)opt + optlen; 1123 *bp++ = TCPOPT_SIGNATURE; 1124 *bp++ = TCPOLEN_SIGNATURE; 1125 sigoff = optlen + 2; 1126 bzero(bp, TCP_SIGLEN); 1127 bp += TCP_SIGLEN; 1128 optlen += TCPOLEN_SIGNATURE; 1129 /* 1130 * Terminate options list and maintain 32-bit alignment. 1131 */ 1132 *bp++ = TCPOPT_NOP; 1133 *bp++ = TCPOPT_EOL; 1134 optlen += 2; 1135 } 1136 #endif /* TCP_SIGNATURE */ 1137 1138 hdrlen += optlen; 1139 1140 #ifdef DIAGNOSTIC 1141 if (!use_tso && len > txsegsize) 1142 panic("tcp data to be sent is larger than segment"); 1143 else if (use_tso && len > IP_MAXPACKET) 1144 panic("tcp data to be sent is larger than max TSO size"); 1145 if (max_linkhdr + hdrlen > MCLBYTES) 1146 panic("tcphdr too big"); 1147 #endif 1148 1149 /* 1150 * Grab a header mbuf, attaching a copy of data to 1151 * be transmitted, and initialize the header from 1152 * the template for sends on this connection. 1153 */ 1154 if (len) { 1155 error = tcp_build_datapkt(tp, so, off, len, hdrlen, &m); 1156 if (error) 1157 goto out; 1158 /* 1159 * If we're sending everything we've got, set PUSH. 1160 * (This will keep happy those implementations which only 1161 * give data to the user when a buffer fills or 1162 * a PUSH comes in.) 1163 */ 1164 if (off + len == so->so_snd.sb_cc) 1165 flags |= TH_PUSH; 1166 } else { 1167 if (tp->t_flags & TF_ACKNOW) 1168 tcpstat.tcps_sndacks++; 1169 else if (flags & (TH_SYN|TH_FIN|TH_RST)) 1170 tcpstat.tcps_sndctrl++; 1171 else if (SEQ_GT(tp->snd_up, tp->snd_una)) 1172 tcpstat.tcps_sndurg++; 1173 else 1174 tcpstat.tcps_sndwinup++; 1175 1176 MGETHDR(m, M_DONTWAIT, MT_HEADER); 1177 if (m != NULL && max_linkhdr + hdrlen > MHLEN) { 1178 MCLGET(m, M_DONTWAIT); 1179 if ((m->m_flags & M_EXT) == 0) { 1180 m_freem(m); 1181 m = NULL; 1182 } 1183 } 1184 if (m == NULL) { 1185 error = ENOBUFS; 1186 goto out; 1187 } 1188 MCLAIM(m, &tcp_tx_mowner); 1189 m->m_data += max_linkhdr; 1190 m->m_len = hdrlen; 1191 } 1192 m->m_pkthdr.rcvif = (struct ifnet *)0; 1193 switch (af) { 1194 #ifdef INET 1195 case AF_INET: 1196 ip = mtod(m, struct ip *); 1197 #ifdef INET6 1198 ip6 = NULL; 1199 #endif 1200 th = (struct tcphdr *)(ip + 1); 1201 break; 1202 #endif 1203 #ifdef INET6 1204 case AF_INET6: 1205 ip = NULL; 1206 ip6 = mtod(m, struct ip6_hdr *); 1207 th = (struct tcphdr *)(ip6 + 1); 1208 break; 1209 #endif 1210 default: /*pacify gcc*/ 1211 ip = NULL; 1212 #ifdef INET6 1213 ip6 = NULL; 1214 #endif 1215 th = NULL; 1216 break; 1217 } 1218 if (tp->t_template == 0) 1219 panic("tcp_output"); 1220 if (tp->t_template->m_len < iphdrlen) 1221 panic("tcp_output"); 1222 bcopy(mtod(tp->t_template, caddr_t), mtod(m, caddr_t), iphdrlen); 1223 1224 /* 1225 * If we are doing retransmissions, then snd_nxt will 1226 * not reflect the first unsent octet. For ACK only 1227 * packets, we do not want the sequence number of the 1228 * retransmitted packet, we want the sequence number 1229 * of the next unsent octet. So, if there is no data 1230 * (and no SYN or FIN), use snd_max instead of snd_nxt 1231 * when filling in ti_seq. But if we are in persist 1232 * state, snd_max might reflect one byte beyond the 1233 * right edge of the window, so use snd_nxt in that 1234 * case, since we know we aren't doing a retransmission. 1235 * (retransmit and persist are mutually exclusive...) 1236 */ 1237 if (TCP_SACK_ENABLED(tp) && sack_rxmit) { 1238 th->th_seq = htonl(p->rxmit); 1239 p->rxmit += len; 1240 } else { 1241 if (len || (flags & (TH_SYN|TH_FIN)) || 1242 TCP_TIMER_ISARMED(tp, TCPT_PERSIST)) 1243 th->th_seq = htonl(tp->snd_nxt); 1244 else 1245 th->th_seq = htonl(tp->snd_max); 1246 } 1247 th->th_ack = htonl(tp->rcv_nxt); 1248 if (optlen) { 1249 bcopy((caddr_t)opt, (caddr_t)(th + 1), optlen); 1250 th->th_off = (sizeof (struct tcphdr) + optlen) >> 2; 1251 } 1252 th->th_flags = flags; 1253 /* 1254 * Calculate receive window. Don't shrink window, 1255 * but avoid silly window syndrome. 1256 */ 1257 if (win < (long)(so->so_rcv.sb_hiwat / 4) && win < (long)rxsegsize) 1258 win = 0; 1259 if (win > (long)TCP_MAXWIN << tp->rcv_scale) 1260 win = (long)TCP_MAXWIN << tp->rcv_scale; 1261 if (win < (long)(int32_t)(tp->rcv_adv - tp->rcv_nxt)) 1262 win = (long)(int32_t)(tp->rcv_adv - tp->rcv_nxt); 1263 th->th_win = htons((u_int16_t) (win>>tp->rcv_scale)); 1264 if (SEQ_GT(tp->snd_up, tp->snd_nxt)) { 1265 u_int32_t urp = tp->snd_up - tp->snd_nxt; 1266 if (urp > IP_MAXPACKET) 1267 urp = IP_MAXPACKET; 1268 th->th_urp = htons((u_int16_t)urp); 1269 th->th_flags |= TH_URG; 1270 } else 1271 /* 1272 * If no urgent pointer to send, then we pull 1273 * the urgent pointer to the left edge of the send window 1274 * so that it doesn't drift into the send window on sequence 1275 * number wraparound. 1276 */ 1277 tp->snd_up = tp->snd_una; /* drag it along */ 1278 1279 #ifdef TCP_SIGNATURE 1280 #if defined(INET6) && defined(FAST_IPSEC) 1281 if (tp->t_family == AF_INET) /* XXX */ 1282 #endif 1283 if (sigoff && (tp->t_flags & TF_SIGNATURE)) { 1284 struct secasvar *sav; 1285 u_int8_t *sigp; 1286 1287 sav = tcp_signature_getsav(m, th); 1288 1289 if (sav == NULL) { 1290 if (m) 1291 m_freem(m); 1292 return (EPERM); 1293 } 1294 1295 m->m_pkthdr.len = hdrlen + len; 1296 sigp = (caddr_t)th + sizeof(*th) + sigoff; 1297 tcp_signature(m, th, (caddr_t)th - mtod(m, caddr_t), sav, sigp); 1298 1299 key_sa_recordxfer(sav, m); 1300 #ifdef FAST_IPSEC 1301 KEY_FREESAV(&sav); 1302 #else 1303 key_freesav(sav); 1304 #endif 1305 } 1306 #endif 1307 1308 /* 1309 * Set ourselves up to be checksummed just before the packet 1310 * hits the wire. 1311 */ 1312 switch (af) { 1313 #ifdef INET 1314 case AF_INET: 1315 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 1316 if (use_tso) { 1317 m->m_pkthdr.segsz = txsegsize; 1318 m->m_pkthdr.csum_flags = M_CSUM_TSOv4; 1319 } else { 1320 m->m_pkthdr.csum_flags = M_CSUM_TCPv4; 1321 if (len + optlen) { 1322 /* Fixup the pseudo-header checksum. */ 1323 /* XXXJRT Not IP Jumbogram safe. */ 1324 th->th_sum = in_cksum_addword(th->th_sum, 1325 htons((u_int16_t) (len + optlen))); 1326 } 1327 } 1328 break; 1329 #endif 1330 #ifdef INET6 1331 case AF_INET6: 1332 /* 1333 * XXX Actually delaying the checksum is Hard 1334 * XXX (well, maybe not for Itojun, but it is 1335 * XXX for me), but we can still take advantage 1336 * XXX of the cached pseudo-header checksum. 1337 */ 1338 /* equals to hdrlen + len */ 1339 m->m_pkthdr.len = sizeof(struct ip6_hdr) 1340 + sizeof(struct tcphdr) + optlen + len; 1341 #ifdef notyet 1342 m->m_pkthdr.csum_flags = M_CSUM_TCPv6; 1343 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 1344 #endif 1345 if (len + optlen) { 1346 /* Fixup the pseudo-header checksum. */ 1347 /* XXXJRT: Not IPv6 Jumbogram safe. */ 1348 th->th_sum = in_cksum_addword(th->th_sum, 1349 htons((u_int16_t) (len + optlen))); 1350 } 1351 th->th_sum = in6_cksum(m, 0, sizeof(struct ip6_hdr), 1352 sizeof(struct tcphdr) + optlen + len); 1353 break; 1354 #endif 1355 } 1356 1357 /* 1358 * In transmit state, time the transmission and arrange for 1359 * the retransmit. In persist state, just set snd_max. 1360 */ 1361 if (tp->t_force == 0 || TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) { 1362 tcp_seq startseq = tp->snd_nxt; 1363 1364 /* 1365 * Advance snd_nxt over sequence space of this segment. 1366 * There are no states in which we send both a SYN and a FIN, 1367 * so we collapse the tests for these flags. 1368 */ 1369 if (flags & (TH_SYN|TH_FIN)) 1370 tp->snd_nxt++; 1371 if (sack_rxmit) 1372 goto timer; 1373 tp->snd_nxt += len; 1374 if (SEQ_GT(tp->snd_nxt, tp->snd_max)) { 1375 tp->snd_max = tp->snd_nxt; 1376 /* 1377 * Time this transmission if not a retransmission and 1378 * not currently timing anything. 1379 */ 1380 if (tp->t_rtttime == 0) { 1381 tp->t_rtttime = tcp_now; 1382 tp->t_rtseq = startseq; 1383 tcpstat.tcps_segstimed++; 1384 } 1385 } 1386 1387 /* 1388 * Set retransmit timer if not currently set, 1389 * and not doing an ack or a keep-alive probe. 1390 * Initial value for retransmit timer is smoothed 1391 * round-trip time + 2 * round-trip time variance. 1392 * Initialize shift counter which is used for backoff 1393 * of retransmit time. 1394 */ 1395 timer: 1396 if (TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 && 1397 ((sack_rxmit && tp->snd_nxt != tp->snd_max) || 1398 tp->snd_nxt != tp->snd_una)) { 1399 if (TCP_TIMER_ISARMED(tp, TCPT_PERSIST)) { 1400 TCP_TIMER_DISARM(tp, TCPT_PERSIST); 1401 tp->t_rxtshift = 0; 1402 } 1403 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 1404 } 1405 } else 1406 if (SEQ_GT(tp->snd_nxt + len, tp->snd_max)) 1407 tp->snd_max = tp->snd_nxt + len; 1408 1409 #ifdef TCP_DEBUG 1410 /* 1411 * Trace. 1412 */ 1413 if (so->so_options & SO_DEBUG) 1414 tcp_trace(TA_OUTPUT, tp->t_state, tp, m, 0); 1415 #endif 1416 1417 /* 1418 * Fill in IP length and desired time to live and 1419 * send to IP level. There should be a better way 1420 * to handle ttl and tos; we could keep them in 1421 * the template, but need a way to checksum without them. 1422 */ 1423 m->m_pkthdr.len = hdrlen + len; 1424 1425 switch (af) { 1426 #ifdef INET 1427 case AF_INET: 1428 ip->ip_len = htons(m->m_pkthdr.len); 1429 if (tp->t_inpcb) { 1430 ip->ip_ttl = tp->t_inpcb->inp_ip.ip_ttl; 1431 ip->ip_tos = tp->t_inpcb->inp_ip.ip_tos; 1432 } 1433 #ifdef INET6 1434 else if (tp->t_in6pcb) { 1435 ip->ip_ttl = in6_selecthlim(tp->t_in6pcb, NULL); /*XXX*/ 1436 ip->ip_tos = 0; /*XXX*/ 1437 } 1438 #endif 1439 break; 1440 #endif 1441 #ifdef INET6 1442 case AF_INET6: 1443 ip6->ip6_nxt = IPPROTO_TCP; 1444 if (tp->t_in6pcb) { 1445 /* 1446 * we separately set hoplimit for every segment, since 1447 * the user might want to change the value via 1448 * setsockopt. Also, desired default hop limit might 1449 * be changed via Neighbor Discovery. 1450 */ 1451 ip6->ip6_hlim = in6_selecthlim(tp->t_in6pcb, 1452 ro->ro_rt ? ro->ro_rt->rt_ifp : NULL); 1453 } 1454 /* ip6->ip6_flow = ??? */ 1455 /* ip6_plen will be filled in ip6_output(). */ 1456 break; 1457 #endif 1458 } 1459 1460 switch (af) { 1461 #ifdef INET 1462 case AF_INET: 1463 { 1464 struct mbuf *opts; 1465 1466 if (tp->t_inpcb) 1467 opts = tp->t_inpcb->inp_options; 1468 else 1469 opts = NULL; 1470 error = ip_output(m, opts, ro, 1471 (tp->t_mtudisc ? IP_MTUDISC : 0) | 1472 (so->so_options & SO_DONTROUTE), 1473 (struct ip_moptions *)0, so); 1474 break; 1475 } 1476 #endif 1477 #ifdef INET6 1478 case AF_INET6: 1479 { 1480 struct ip6_pktopts *opts; 1481 1482 if (tp->t_in6pcb) 1483 opts = tp->t_in6pcb->in6p_outputopts; 1484 else 1485 opts = NULL; 1486 error = ip6_output(m, opts, (struct route_in6 *)ro, 1487 so->so_options & SO_DONTROUTE, 1488 (struct ip6_moptions *)0, so, NULL); 1489 break; 1490 } 1491 #endif 1492 default: 1493 error = EAFNOSUPPORT; 1494 break; 1495 } 1496 if (error) { 1497 out: 1498 if (error == ENOBUFS) { 1499 tcpstat.tcps_selfquench++; 1500 #ifdef INET 1501 if (tp->t_inpcb) 1502 tcp_quench(tp->t_inpcb, 0); 1503 #endif 1504 #ifdef INET6 1505 if (tp->t_in6pcb) 1506 tcp6_quench(tp->t_in6pcb, 0); 1507 #endif 1508 error = 0; 1509 } else if ((error == EHOSTUNREACH || error == ENETDOWN) && 1510 TCPS_HAVERCVDSYN(tp->t_state)) { 1511 tp->t_softerror = error; 1512 error = 0; 1513 } 1514 1515 /* Back out the seqence number advance. */ 1516 if (sack_rxmit) 1517 p->rxmit -= len; 1518 1519 /* Restart the delayed ACK timer, if necessary. */ 1520 if (tp->t_flags & TF_DELACK) 1521 TCP_RESTART_DELACK(tp); 1522 1523 return (error); 1524 } 1525 tcpstat.tcps_sndtotal++; 1526 if (tp->t_flags & TF_DELACK) 1527 tcpstat.tcps_delack++; 1528 1529 /* 1530 * Data sent (as far as we can tell). 1531 * If this advertises a larger window than any other segment, 1532 * then remember the size of the advertised window. 1533 * Any pending ACK has now been sent. 1534 */ 1535 if (win > 0 && SEQ_GT(tp->rcv_nxt+win, tp->rcv_adv)) 1536 tp->rcv_adv = tp->rcv_nxt + win; 1537 tp->last_ack_sent = tp->rcv_nxt; 1538 tp->t_flags &= ~TF_ACKNOW; 1539 TCP_CLEAR_DELACK(tp); 1540 #ifdef DIAGNOSTIC 1541 if (maxburst < 0) 1542 printf("tcp_output: maxburst exceeded by %d\n", -maxburst); 1543 #endif 1544 if (sendalot && (!tcp_do_newreno || --maxburst)) 1545 goto again; 1546 return (0); 1547 } 1548 1549 void 1550 tcp_setpersist(struct tcpcb *tp) 1551 { 1552 int t = ((tp->t_srtt >> 2) + tp->t_rttvar) >> (1 + 2); 1553 int nticks; 1554 1555 if (TCP_TIMER_ISARMED(tp, TCPT_REXMT)) 1556 panic("tcp_output REXMT"); 1557 /* 1558 * Start/restart persistance timer. 1559 */ 1560 if (t < tp->t_rttmin) 1561 t = tp->t_rttmin; 1562 TCPT_RANGESET(nticks, t * tcp_backoff[tp->t_rxtshift], 1563 TCPTV_PERSMIN, TCPTV_PERSMAX); 1564 TCP_TIMER_ARM(tp, TCPT_PERSIST, nticks); 1565 if (tp->t_rxtshift < TCP_MAXRXTSHIFT) 1566 tp->t_rxtshift++; 1567 } 1568 1569 /* 1570 * tcp4_segment: handle M_CSUM_TSOv4 by software. 1571 * 1572 * => always consume m. 1573 * => call output_func with output_arg for each segments. 1574 */ 1575 1576 int 1577 tcp4_segment(struct mbuf *m, int (*output_func)(void *, struct mbuf *), 1578 void *output_arg) 1579 { 1580 int mss; 1581 int iphlen; 1582 int thlen; 1583 int hlen; 1584 int len; 1585 struct ip *iph; 1586 struct tcphdr *th; 1587 uint16_t ipid; 1588 uint32_t tcpseq; 1589 struct mbuf *hdr = NULL; 1590 struct mbuf *t; 1591 int error = 0; 1592 1593 KASSERT((m->m_flags & M_PKTHDR) != 0); 1594 KASSERT((m->m_pkthdr.csum_flags & M_CSUM_TSOv4) != 0); 1595 1596 m->m_pkthdr.csum_flags = 0; 1597 1598 len = m->m_pkthdr.len; 1599 KASSERT(len >= sizeof(*iph) + sizeof(*th)); 1600 1601 if (m->m_len < sizeof(*iph)) { 1602 m = m_pullup(m, sizeof(*iph)); 1603 if (m == NULL) { 1604 error = ENOMEM; 1605 goto quit; 1606 } 1607 } 1608 iph = mtod(m, struct ip *); 1609 iphlen = iph->ip_hl * 4; 1610 KASSERT(iph->ip_v == IPVERSION); 1611 KASSERT(iphlen >= sizeof(*iph)); 1612 KASSERT(iph->ip_p == IPPROTO_TCP); 1613 ipid = ntohs(iph->ip_id); 1614 1615 hlen = iphlen + sizeof(*th); 1616 if (m->m_len < hlen) { 1617 m = m_pullup(m, hlen); 1618 if (m == NULL) { 1619 error = ENOMEM; 1620 goto quit; 1621 } 1622 } 1623 th = (void *)(mtod(m, char *) + iphlen); 1624 tcpseq = ntohl(th->th_seq); 1625 thlen = th->th_off * 4; 1626 hlen = iphlen + thlen; 1627 1628 mss = m->m_pkthdr.segsz; 1629 KASSERT(mss != 0); 1630 KASSERT(len > hlen); 1631 1632 t = m_split(m, hlen, M_NOWAIT); 1633 if (t == NULL) { 1634 error = ENOMEM; 1635 goto quit; 1636 } 1637 hdr = m; 1638 m = t; 1639 len -= hlen; 1640 KASSERT(len % mss == 0); 1641 while (len > 0) { 1642 struct mbuf *n; 1643 1644 n = m_dup(hdr, 0, hlen, M_NOWAIT); 1645 if (n == NULL) { 1646 error = ENOMEM; 1647 goto quit; 1648 } 1649 KASSERT(n->m_len == hlen); /* XXX */ 1650 1651 t = m_split(m, mss, M_NOWAIT); 1652 if (t == NULL) { 1653 m_freem(n); 1654 error = ENOMEM; 1655 goto quit; 1656 } 1657 m_cat(n, m); 1658 m = t; 1659 1660 KASSERT(n->m_len >= hlen); /* XXX */ 1661 1662 n->m_pkthdr.len = hlen + mss; 1663 iph = mtod(n, struct ip *); 1664 KASSERT(iph->ip_v == IPVERSION); 1665 iph->ip_len = htons(n->m_pkthdr.len); 1666 iph->ip_id = htons(ipid); 1667 th = (void *)(mtod(n, char *) + iphlen); 1668 th->th_seq = htonl(tcpseq); 1669 iph->ip_sum = 0; 1670 iph->ip_sum = in_cksum(n, iphlen); 1671 th->th_sum = 0; 1672 th->th_sum = in4_cksum(n, IPPROTO_TCP, iphlen, thlen + mss); 1673 1674 error = (*output_func)(output_arg, n); 1675 if (error) { 1676 goto quit; 1677 } 1678 1679 tcpseq += mss; 1680 ipid++; 1681 len -= mss; 1682 } 1683 1684 quit: 1685 if (hdr != NULL) { 1686 m_freem(hdr); 1687 } 1688 if (m != NULL) { 1689 m_freem(m); 1690 } 1691 1692 return error; 1693 } 1694