1 /* $OpenBSD: tcp_output.c,v 1.151 2025/01/05 12:18:48 bluhm Exp $ */ 2 /* $NetBSD: tcp_output.c,v 1.16 1997/06/03 16:17:09 kml Exp $ */ 3 4 /* 5 * Copyright (c) 1982, 1986, 1988, 1990, 1993 6 * The Regents of the University of California. All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * @(#)COPYRIGHT 1.1 (NRL) 17 January 1995 33 * 34 * NRL grants permission for redistribution and use in source and binary 35 * forms, with or without modification, of the software and documentation 36 * created at NRL provided that the following conditions are met: 37 * 38 * 1. Redistributions of source code must retain the above copyright 39 * notice, this list of conditions and the following disclaimer. 40 * 2. Redistributions in binary form must reproduce the above copyright 41 * notice, this list of conditions and the following disclaimer in the 42 * documentation and/or other materials provided with the distribution. 43 * 3. All advertising materials mentioning features or use of this software 44 * must display the following acknowledgements: 45 * This product includes software developed by the University of 46 * California, Berkeley and its contributors. 47 * This product includes software developed at the Information 48 * Technology Division, US Naval Research Laboratory. 49 * 4. Neither the name of the NRL nor the names of its contributors 50 * may be used to endorse or promote products derived from this software 51 * without specific prior written permission. 52 * 53 * THE SOFTWARE PROVIDED BY NRL IS PROVIDED BY NRL AND CONTRIBUTORS ``AS 54 * IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 55 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A 56 * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL NRL OR 57 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 58 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 59 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 60 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF 61 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 62 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 63 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 64 * 65 * The views and conclusions contained in the software and documentation 66 * are those of the authors and should not be interpreted as representing 67 * official policies, either expressed or implied, of the US Naval 68 * Research Laboratory (NRL). 69 */ 70 71 #include "pf.h" 72 #include "stoeplitz.h" 73 74 #include <sys/param.h> 75 #include <sys/systm.h> 76 #include <sys/mbuf.h> 77 #include <sys/protosw.h> 78 #include <sys/socket.h> 79 #include <sys/socketvar.h> 80 #include <sys/kernel.h> 81 82 #include <net/if.h> 83 #include <net/if_var.h> 84 #include <net/route.h> 85 #if NPF > 0 86 #include <net/pfvar.h> 87 #endif 88 89 #include <netinet/in.h> 90 #include <netinet/ip.h> 91 #include <netinet/in_pcb.h> 92 #include <netinet/ip_var.h> 93 #include <netinet6/ip6_var.h> 94 #include <netinet/tcp.h> 95 #define TCPOUTFLAGS 96 #include <netinet/tcp_fsm.h> 97 #include <netinet/tcp_seq.h> 98 #include <netinet/tcp_timer.h> 99 #include <netinet/tcp_var.h> 100 #include <netinet/tcp_debug.h> 101 102 #ifdef notyet 103 extern struct mbuf *m_copypack(); 104 #endif 105 106 #ifdef TCP_SACK_DEBUG 107 void tcp_print_holes(struct tcpcb *tp); 108 109 void 110 tcp_print_holes(struct tcpcb *tp) 111 { 112 struct sackhole *p = tp->snd_holes; 113 if (p == NULL) 114 return; 115 printf("Hole report: start--end dups rxmit\n"); 116 while (p) { 117 printf("%x--%x d %d r %x\n", p->start, p->end, p->dups, 118 p->rxmit); 119 p = p->next; 120 } 121 printf("\n"); 122 } 123 #endif /* TCP_SACK_DEBUG */ 124 125 /* 126 * Returns pointer to a sackhole if there are any pending retransmissions; 127 * NULL otherwise. 128 */ 129 struct sackhole * 130 tcp_sack_output(struct tcpcb *tp) 131 { 132 struct sackhole *p; 133 134 if (!tp->sack_enable) 135 return (NULL); 136 p = tp->snd_holes; 137 while (p) { 138 if (p->dups >= tcprexmtthresh && SEQ_LT(p->rxmit, p->end)) { 139 if (SEQ_LT(p->rxmit, tp->snd_una)) {/* old SACK hole */ 140 p = p->next; 141 continue; 142 } 143 #ifdef TCP_SACK_DEBUG 144 if (p) 145 tcp_print_holes(tp); 146 #endif 147 return (p); 148 } 149 p = p->next; 150 } 151 return (NULL); 152 } 153 154 /* 155 * After a timeout, the SACK list may be rebuilt. This SACK information 156 * should be used to avoid retransmitting SACKed data. This function 157 * traverses the SACK list to see if snd_nxt should be moved forward. 158 */ 159 160 void 161 tcp_sack_adjust(struct tcpcb *tp) 162 { 163 struct sackhole *cur = tp->snd_holes; 164 if (cur == NULL) 165 return; /* No holes */ 166 if (SEQ_GEQ(tp->snd_nxt, tp->rcv_lastsack)) 167 return; /* We're already beyond any SACKed blocks */ 168 /* 169 * Two cases for which we want to advance snd_nxt: 170 * i) snd_nxt lies between end of one hole and beginning of another 171 * ii) snd_nxt lies between end of last hole and rcv_lastsack 172 */ 173 while (cur->next) { 174 if (SEQ_LT(tp->snd_nxt, cur->end)) 175 return; 176 if (SEQ_GEQ(tp->snd_nxt, cur->next->start)) 177 cur = cur->next; 178 else { 179 tp->snd_nxt = cur->next->start; 180 return; 181 } 182 } 183 if (SEQ_LT(tp->snd_nxt, cur->end)) 184 return; 185 tp->snd_nxt = tp->rcv_lastsack; 186 return; 187 } 188 189 /* 190 * Tcp output routine: figure out what should be sent and send it. 191 */ 192 int 193 tcp_output(struct tcpcb *tp) 194 { 195 struct socket *so = tp->t_inpcb->inp_socket; 196 long len, win, rcv_hiwat, txmaxseg; 197 int off, flags, error; 198 struct mbuf *m; 199 struct tcphdr *th; 200 u_int32_t optbuf[howmany(MAX_TCPOPTLEN, sizeof(u_int32_t))]; 201 u_char *opt = (u_char *)optbuf; 202 unsigned int optlen, hdrlen, packetlen; 203 int doing_sosend, idle, sendalot = 0; 204 int i, sack_rxmit = 0; 205 struct sackhole *p; 206 uint64_t now; 207 #ifdef TCP_SIGNATURE 208 unsigned int sigoff; 209 #endif /* TCP_SIGNATURE */ 210 #ifdef TCP_ECN 211 int do_ecn = atomic_load_int(&tcp_do_ecn); 212 int needect; 213 #endif 214 int tso; 215 216 if (tp->t_flags & TF_BLOCKOUTPUT) { 217 tp->t_flags |= TF_NEEDOUTPUT; 218 return (0); 219 } else 220 tp->t_flags &= ~TF_NEEDOUTPUT; 221 222 #if defined(TCP_SIGNATURE) && defined(DIAGNOSTIC) 223 if (tp->sack_enable && (tp->t_flags & TF_SIGNATURE)) 224 return (EINVAL); 225 #endif /* defined(TCP_SIGNATURE) && defined(DIAGNOSTIC) */ 226 227 now = tcp_now(); 228 229 mtx_enter(&so->so_snd.sb_mtx); 230 doing_sosend = soissending(so); 231 mtx_leave(&so->so_snd.sb_mtx); 232 233 /* 234 * Determine length of data that should be transmitted, 235 * and flags that will be used. 236 * If there is some data or critical controls (SYN, RST) 237 * to send, then transmit; otherwise, investigate further. 238 */ 239 idle = (tp->t_flags & TF_LASTIDLE) || (tp->snd_max == tp->snd_una); 240 if (idle && (now - tp->t_rcvtime) >= tp->t_rxtcur) 241 /* 242 * We have been idle for "a while" and no acks are 243 * expected to clock out any data we send -- 244 * slow start to get ack "clock" running again. 245 */ 246 tp->snd_cwnd = 2 * tp->t_maxseg; 247 248 /* remember 'idle' for next invocation of tcp_output */ 249 if (idle && doing_sosend) { 250 tp->t_flags |= TF_LASTIDLE; 251 idle = 0; 252 } else 253 tp->t_flags &= ~TF_LASTIDLE; 254 255 again: 256 /* 257 * If we've recently taken a timeout, snd_max will be greater than 258 * snd_nxt. There may be SACK information that allows us to avoid 259 * resending already delivered data. Adjust snd_nxt accordingly. 260 */ 261 if (tp->sack_enable && SEQ_LT(tp->snd_nxt, tp->snd_max)) 262 tcp_sack_adjust(tp); 263 off = tp->snd_nxt - tp->snd_una; 264 win = ulmin(tp->snd_wnd, tp->snd_cwnd); 265 266 flags = tcp_outflags[tp->t_state]; 267 268 /* 269 * Send any SACK-generated retransmissions. If we're explicitly trying 270 * to send out new data (when sendalot is 1), bypass this function. 271 * If we retransmit in fast recovery mode, decrement snd_cwnd, since 272 * we're replacing a (future) new transmission with a retransmission 273 * now, and we previously incremented snd_cwnd in tcp_input(). 274 */ 275 if (tp->sack_enable && !sendalot) { 276 if (tp->t_dupacks >= tcprexmtthresh && 277 (p = tcp_sack_output(tp))) { 278 off = p->rxmit - tp->snd_una; 279 sack_rxmit = 1; 280 /* Coalesce holes into a single retransmission */ 281 len = min(tp->t_maxseg, p->end - p->rxmit); 282 if (SEQ_LT(tp->snd_una, tp->snd_last)) 283 tp->snd_cwnd -= tp->t_maxseg; 284 } 285 } 286 287 sendalot = 0; 288 tso = 0; 289 /* 290 * If in persist timeout with window of 0, send 1 byte. 291 * Otherwise, if window is small but nonzero 292 * and timer expired, we will send what we can 293 * and go to transmit state. 294 */ 295 if (tp->t_force) { 296 if (win == 0) { 297 /* 298 * If we still have some data to send, then 299 * clear the FIN bit. Usually this would 300 * happen below when it realizes that we 301 * aren't sending all the data. However, 302 * if we have exactly 1 byte of unset data, 303 * then it won't clear the FIN bit below, 304 * and if we are in persist state, we wind 305 * up sending the packet without recording 306 * that we sent the FIN bit. 307 * 308 * We can't just blindly clear the FIN bit, 309 * because if we don't have any more data 310 * to send then the probe will be the FIN 311 * itself. 312 */ 313 if (off < so->so_snd.sb_cc) 314 flags &= ~TH_FIN; 315 win = 1; 316 } else { 317 TCP_TIMER_DISARM(tp, TCPT_PERSIST); 318 tp->t_rxtshift = 0; 319 } 320 } 321 322 if (!sack_rxmit) { 323 len = ulmin(so->so_snd.sb_cc, win) - off; 324 } 325 326 if (len < 0) { 327 /* 328 * If FIN has been sent but not acked, 329 * but we haven't been called to retransmit, 330 * len will be -1. Otherwise, window shrank 331 * after we sent into it. If window shrank to 0, 332 * cancel pending retransmit, pull snd_nxt back 333 * to (closed) window, and set the persist timer 334 * if it isn't already going. If the window didn't 335 * close completely, just wait for an ACK. 336 */ 337 len = 0; 338 if (win == 0) { 339 TCP_TIMER_DISARM(tp, TCPT_REXMT); 340 tp->t_rxtshift = 0; 341 tp->snd_nxt = tp->snd_una; 342 if (TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) 343 tcp_setpersist(tp); 344 } 345 } 346 347 /* 348 * Never send more than half a buffer full. This insures that we can 349 * always keep 2 packets on the wire, no matter what SO_SNDBUF is, and 350 * therefore acks will never be delayed unless we run out of data to 351 * transmit. 352 */ 353 txmaxseg = ulmin(so->so_snd.sb_hiwat / 2, tp->t_maxseg); 354 355 if (len > txmaxseg) { 356 if (atomic_load_int(&tcp_do_tso) && 357 tp->t_inpcb->inp_options == NULL && 358 tp->t_inpcb->inp_outputopts6 == NULL && 359 #ifdef TCP_SIGNATURE 360 ((tp->t_flags & TF_SIGNATURE) == 0) && 361 #endif 362 len >= 2 * tp->t_maxseg && 363 tp->rcv_numsacks == 0 && sack_rxmit == 0 && 364 !(flags & (TH_SYN|TH_RST|TH_FIN))) { 365 tso = 1; 366 /* avoid small chopped packets */ 367 if (len > (len / tp->t_maxseg) * tp->t_maxseg) { 368 len = (len / tp->t_maxseg) * tp->t_maxseg; 369 sendalot = 1; 370 } 371 } else { 372 len = txmaxseg; 373 sendalot = 1; 374 } 375 } 376 if (off + len < so->so_snd.sb_cc) 377 flags &= ~TH_FIN; 378 379 mtx_enter(&so->so_rcv.sb_mtx); 380 win = sbspace_locked(so, &so->so_rcv); 381 rcv_hiwat = (long) so->so_rcv.sb_hiwat; 382 mtx_leave(&so->so_rcv.sb_mtx); 383 384 /* 385 * Sender silly window avoidance. If connection is idle 386 * and can send all data, a maximum segment, 387 * at least a maximum default-size segment do it, 388 * or are forced, do it; otherwise don't bother. 389 * If peer's buffer is tiny, then send 390 * when window is at least half open. 391 * If retransmitting (possibly after persist timer forced us 392 * to send into a small window), then must resend. 393 */ 394 if (len) { 395 if (len >= txmaxseg) 396 goto send; 397 if ((idle || (tp->t_flags & TF_NODELAY)) && 398 len + off >= so->so_snd.sb_cc && !doing_sosend && 399 (tp->t_flags & TF_NOPUSH) == 0) 400 goto send; 401 if (tp->t_force) 402 goto send; 403 if (len >= tp->max_sndwnd / 2 && tp->max_sndwnd > 0) 404 goto send; 405 if (SEQ_LT(tp->snd_nxt, tp->snd_max)) 406 goto send; 407 if (sack_rxmit) 408 goto send; 409 } 410 411 /* 412 * Compare available window to amount of window 413 * known to peer (as advertised window less 414 * next expected input). If the difference is at least two 415 * max size segments, or at least 50% of the maximum possible 416 * window, then want to send a window update to peer. 417 */ 418 if (win > 0) { 419 /* 420 * "adv" is the amount we can increase the window, 421 * taking into account that we are limited by 422 * TCP_MAXWIN << tp->rcv_scale. 423 */ 424 long adv = lmin(win, (long)TCP_MAXWIN << tp->rcv_scale) - 425 (tp->rcv_adv - tp->rcv_nxt); 426 427 if (adv >= (long) (2 * tp->t_maxseg)) 428 goto send; 429 if (2 * adv >= rcv_hiwat) 430 goto send; 431 } 432 433 /* 434 * Send if we owe peer an ACK. 435 */ 436 if (tp->t_flags & TF_ACKNOW) 437 goto send; 438 if (flags & (TH_SYN|TH_RST)) 439 goto send; 440 if (SEQ_GT(tp->snd_up, tp->snd_una)) 441 goto send; 442 /* 443 * If our state indicates that FIN should be sent 444 * and we have not yet done so, or we're retransmitting the FIN, 445 * then we need to send. 446 */ 447 if (flags & TH_FIN && 448 ((tp->t_flags & TF_SENTFIN) == 0 || tp->snd_nxt == tp->snd_una)) 449 goto send; 450 /* 451 * In SACK, it is possible for tcp_output to fail to send a segment 452 * after the retransmission timer has been turned off. Make sure 453 * that the retransmission timer is set. 454 */ 455 if (SEQ_GT(tp->snd_max, tp->snd_una) && 456 TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 && 457 TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) { 458 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 459 return (0); 460 } 461 462 /* 463 * TCP window updates are not reliable, rather a polling protocol 464 * using ``persist'' packets is used to insure receipt of window 465 * updates. The three ``states'' for the output side are: 466 * idle not doing retransmits or persists 467 * persisting to move a small or zero window 468 * (re)transmitting and thereby not persisting 469 * 470 * tp->t_timer[TCPT_PERSIST] 471 * is set when we are in persist state. 472 * tp->t_force 473 * is set when we are called to send a persist packet. 474 * tp->t_timer[TCPT_REXMT] 475 * is set when we are retransmitting 476 * The output side is idle when both timers are zero. 477 * 478 * If send window is too small, there is data to transmit, and no 479 * retransmit or persist is pending, then go to persist state. 480 * If nothing happens soon, send when timer expires: 481 * if window is nonzero, transmit what we can, 482 * otherwise force out a byte. 483 */ 484 if (so->so_snd.sb_cc && TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 && 485 TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) { 486 tp->t_rxtshift = 0; 487 tcp_setpersist(tp); 488 } 489 490 /* 491 * No reason to send a segment, just return. 492 */ 493 return (0); 494 495 send: 496 /* 497 * Before ESTABLISHED, force sending of initial options 498 * unless TCP set not to do any options. 499 * NOTE: we assume that the IP/TCP header plus TCP options 500 * always fit in a single mbuf, leaving room for a maximum 501 * link header, i.e. 502 * max_linkhdr + sizeof(network header) + sizeof(struct tcphdr + 503 * optlen <= MHLEN 504 */ 505 optlen = 0; 506 507 switch (tp->pf) { 508 case 0: /*default to PF_INET*/ 509 case PF_INET: 510 hdrlen = sizeof(struct ip) + sizeof(struct tcphdr); 511 break; 512 #ifdef INET6 513 case PF_INET6: 514 hdrlen = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 515 break; 516 #endif /* INET6 */ 517 default: 518 return (EPFNOSUPPORT); 519 } 520 521 if (flags & TH_SYN) { 522 tp->snd_nxt = tp->iss; 523 if ((tp->t_flags & TF_NOOPT) == 0) { 524 u_int16_t mss; 525 526 opt[0] = TCPOPT_MAXSEG; 527 opt[1] = 4; 528 mss = htons((u_int16_t) tcp_mss(tp, 0)); 529 memcpy(opt + 2, &mss, sizeof(mss)); 530 optlen = 4; 531 532 if (flags & TH_ACK) 533 tcp_mss_update(tp); 534 /* 535 * If this is the first SYN of connection (not a SYN 536 * ACK), include SACK_PERMIT_HDR option. If this is a 537 * SYN ACK, include SACK_PERMIT_HDR option if peer has 538 * already done so. 539 */ 540 if (tp->sack_enable && ((flags & TH_ACK) == 0 || 541 (tp->t_flags & TF_SACK_PERMIT))) { 542 *((u_int32_t *) (opt + optlen)) = 543 htonl(TCPOPT_SACK_PERMIT_HDR); 544 optlen += 4; 545 } 546 if ((tp->t_flags & TF_REQ_SCALE) && 547 ((flags & TH_ACK) == 0 || 548 (tp->t_flags & TF_RCVD_SCALE))) { 549 *((u_int32_t *) (opt + optlen)) = htonl( 550 TCPOPT_NOP << 24 | 551 TCPOPT_WINDOW << 16 | 552 TCPOLEN_WINDOW << 8 | 553 tp->request_r_scale); 554 optlen += 4; 555 } 556 } 557 } 558 559 /* 560 * Send a timestamp and echo-reply if this is a SYN and our side 561 * wants to use timestamps (TF_REQ_TSTMP is set) or both our side 562 * and our peer have sent timestamps in our SYN's. 563 */ 564 if ((tp->t_flags & (TF_REQ_TSTMP|TF_NOOPT)) == TF_REQ_TSTMP && 565 (flags & TH_RST) == 0 && 566 ((flags & (TH_SYN|TH_ACK)) == TH_SYN || 567 (tp->t_flags & TF_RCVD_TSTMP))) { 568 u_int32_t *lp = (u_int32_t *)(opt + optlen); 569 570 /* Form timestamp option as shown in appendix A of RFC 1323. */ 571 *lp++ = htonl(TCPOPT_TSTAMP_HDR); 572 *lp++ = htonl(now + tp->ts_modulate); 573 *lp = htonl(tp->ts_recent); 574 optlen += TCPOLEN_TSTAMP_APPA; 575 } 576 /* Set receive buffer autosizing timestamp. */ 577 if (tp->rfbuf_ts == 0) { 578 tp->rfbuf_ts = now; 579 tp->rfbuf_cnt = 0; 580 } 581 582 #ifdef TCP_SIGNATURE 583 if (tp->t_flags & TF_SIGNATURE) { 584 u_int8_t *bp = (u_int8_t *)(opt + optlen); 585 586 /* Send signature option */ 587 *(bp++) = TCPOPT_SIGNATURE; 588 *(bp++) = TCPOLEN_SIGNATURE; 589 sigoff = optlen + 2; 590 591 { 592 unsigned int i; 593 594 for (i = 0; i < 16; i++) 595 *(bp++) = 0; 596 } 597 598 599 /* Pad options list to the next 32 bit boundary and 600 * terminate it. 601 */ 602 *bp++ = TCPOPT_NOP; 603 *bp++ = TCPOPT_NOP; 604 605 optlen += TCPOLEN_SIGLEN; 606 } 607 #endif /* TCP_SIGNATURE */ 608 609 /* 610 * Send SACKs if necessary. This should be the last option processed. 611 * Only as many SACKs are sent as are permitted by the maximum options 612 * size. No more than three SACKs are sent. 613 */ 614 if (tp->sack_enable && tp->t_state == TCPS_ESTABLISHED && 615 (tp->t_flags & (TF_SACK_PERMIT|TF_NOOPT)) == TF_SACK_PERMIT && 616 tp->rcv_numsacks) { 617 u_int32_t *lp = (u_int32_t *)(opt + optlen); 618 u_int32_t *olp = lp++; 619 int count = 0; /* actual number of SACKs inserted */ 620 int maxsack = (MAX_TCPOPTLEN - (optlen + 4))/TCPOLEN_SACK; 621 622 tcpstat_inc(tcps_sack_snd_opts); 623 maxsack = min(maxsack, TCP_MAX_SACK); 624 for (i = 0; (i < tp->rcv_numsacks && count < maxsack); i++) { 625 struct sackblk sack = tp->sackblks[i]; 626 if (sack.start == 0 && sack.end == 0) 627 continue; 628 *lp++ = htonl(sack.start); 629 *lp++ = htonl(sack.end); 630 count++; 631 } 632 *olp = htonl(TCPOPT_SACK_HDR|(TCPOLEN_SACK*count+2)); 633 optlen += TCPOLEN_SACK*count + 4; /* including leading NOPs */ 634 } 635 636 #ifdef DIAGNOSTIC 637 if (optlen > MAX_TCPOPTLEN) 638 panic("tcp_output: options too long"); 639 #endif /* DIAGNOSTIC */ 640 641 hdrlen += optlen; 642 643 /* 644 * Adjust data length if insertion of options will 645 * bump the packet length beyond the t_maxopd length. 646 * Clear the FIN bit because we cut off the tail of 647 * the segment. 648 */ 649 if (len > tp->t_maxopd - optlen) { 650 if (tso) { 651 if (len + hdrlen + max_linkhdr > MAXMCLBYTES) { 652 len = MAXMCLBYTES - hdrlen - max_linkhdr; 653 sendalot = 1; 654 } 655 } else { 656 len = tp->t_maxopd - optlen; 657 sendalot = 1; 658 } 659 flags &= ~TH_FIN; 660 } 661 662 #ifdef DIAGNOSTIC 663 if (max_linkhdr + hdrlen > MCLBYTES) 664 panic("tcphdr too big"); 665 #endif 666 667 /* 668 * Grab a header mbuf, attaching a copy of data to 669 * be transmitted, and initialize the header from 670 * the template for sends on this connection. 671 */ 672 if (len) { 673 if (tp->t_force && len == 1) 674 tcpstat_inc(tcps_sndprobe); 675 else if (SEQ_LT(tp->snd_nxt, tp->snd_max)) { 676 tcpstat_pkt(tcps_sndrexmitpack, tcps_sndrexmitbyte, 677 len); 678 tp->t_sndrexmitpack++; 679 } else { 680 tcpstat_pkt(tcps_sndpack, tcps_sndbyte, len); 681 } 682 #ifdef notyet 683 if ((m = m_copypack(so->so_snd.sb_mb, off, 684 (int)len, max_linkhdr + hdrlen)) == 0) { 685 error = ENOBUFS; 686 goto out; 687 } 688 /* 689 * m_copypack left space for our hdr; use it. 690 */ 691 m->m_len += hdrlen; 692 m->m_data -= hdrlen; 693 #else 694 MGETHDR(m, M_DONTWAIT, MT_HEADER); 695 if (m != NULL && max_linkhdr + hdrlen > MHLEN) { 696 MCLGET(m, M_DONTWAIT); 697 if ((m->m_flags & M_EXT) == 0) { 698 m_freem(m); 699 m = NULL; 700 } 701 } 702 if (m == NULL) { 703 error = ENOBUFS; 704 goto out; 705 } 706 m->m_data += max_linkhdr; 707 m->m_len = hdrlen; 708 if (len <= m_trailingspace(m)) { 709 m_copydata(so->so_snd.sb_mb, off, (int) len, 710 mtod(m, caddr_t) + hdrlen); 711 m->m_len += len; 712 } else { 713 m->m_next = m_copym(so->so_snd.sb_mb, off, (int) len, 714 M_NOWAIT); 715 if (m->m_next == 0) { 716 (void) m_free(m); 717 error = ENOBUFS; 718 goto out; 719 } 720 } 721 if (so->so_snd.sb_mb->m_flags & M_PKTHDR) 722 m->m_pkthdr.ph_loopcnt = 723 so->so_snd.sb_mb->m_pkthdr.ph_loopcnt; 724 #endif 725 /* 726 * If we're sending everything we've got, set PUSH. 727 * (This will keep happy those implementations which only 728 * give data to the user when a buffer fills or 729 * a PUSH comes in.) 730 */ 731 if (off + len == so->so_snd.sb_cc && !doing_sosend) 732 flags |= TH_PUSH; 733 tp->t_sndtime = now; 734 } else { 735 if (tp->t_flags & TF_ACKNOW) 736 tcpstat_inc(tcps_sndacks); 737 else if (flags & (TH_SYN|TH_FIN|TH_RST)) 738 tcpstat_inc(tcps_sndctrl); 739 else if (SEQ_GT(tp->snd_up, tp->snd_una)) 740 tcpstat_inc(tcps_sndurg); 741 else 742 tcpstat_inc(tcps_sndwinup); 743 744 MGETHDR(m, M_DONTWAIT, MT_HEADER); 745 if (m != NULL && max_linkhdr + hdrlen > MHLEN) { 746 MCLGET(m, M_DONTWAIT); 747 if ((m->m_flags & M_EXT) == 0) { 748 m_freem(m); 749 m = NULL; 750 } 751 } 752 if (m == NULL) { 753 error = ENOBUFS; 754 goto out; 755 } 756 m->m_data += max_linkhdr; 757 m->m_len = hdrlen; 758 } 759 m->m_pkthdr.ph_ifidx = 0; 760 m->m_pkthdr.len = hdrlen + len; 761 762 /* Enable TSO and specify the size of the resulting segments. */ 763 if (tso) { 764 SET(m->m_pkthdr.csum_flags, M_TCP_TSO); 765 m->m_pkthdr.ph_mss = tp->t_maxseg; 766 } 767 768 if (!tp->t_template) 769 panic("tcp_output"); 770 #ifdef DIAGNOSTIC 771 if (tp->t_template->m_len != hdrlen - optlen) 772 panic("tcp_output: template len != hdrlen - optlen"); 773 #endif /* DIAGNOSTIC */ 774 memcpy(mtod(m, caddr_t), mtod(tp->t_template, caddr_t), 775 tp->t_template->m_len); 776 th = (struct tcphdr *)(mtod(m, caddr_t) + tp->t_template->m_len - 777 sizeof(struct tcphdr)); 778 779 /* 780 * Fill in fields, remembering maximum advertised 781 * window for use in delaying messages about window sizes. 782 * If resending a FIN, be sure not to use a new sequence number. 783 */ 784 if ((flags & TH_FIN) && (tp->t_flags & TF_SENTFIN) && 785 (tp->snd_nxt == tp->snd_max)) 786 tp->snd_nxt--; 787 /* 788 * If we are doing retransmissions, then snd_nxt will 789 * not reflect the first unsent octet. For ACK only 790 * packets, we do not want the sequence number of the 791 * retransmitted packet, we want the sequence number 792 * of the next unsent octet. So, if there is no data 793 * (and no SYN or FIN), use snd_max instead of snd_nxt 794 * when filling in ti_seq. But if we are in persist 795 * state, snd_max might reflect one byte beyond the 796 * right edge of the window, so use snd_nxt in that 797 * case, since we know we aren't doing a retransmission. 798 * (retransmit and persist are mutually exclusive...) 799 */ 800 if (len || (flags & (TH_SYN|TH_FIN)) || 801 TCP_TIMER_ISARMED(tp, TCPT_PERSIST)) 802 th->th_seq = htonl(tp->snd_nxt); 803 else 804 th->th_seq = htonl(tp->snd_max); 805 806 if (sack_rxmit) { 807 /* 808 * If sendalot was turned on (due to option stuffing), turn it 809 * off. Properly set th_seq field. Advance the ret'x pointer 810 * by len. 811 */ 812 if (sendalot) 813 sendalot = 0; 814 th->th_seq = htonl(p->rxmit); 815 p->rxmit += len; 816 tcpstat_pkt(tcps_sack_rexmits, tcps_sack_rexmit_bytes, len); 817 } 818 819 th->th_ack = htonl(tp->rcv_nxt); 820 if (optlen) { 821 memcpy(th + 1, opt, optlen); 822 th->th_off = (sizeof (struct tcphdr) + optlen) >> 2; 823 } 824 #ifdef TCP_ECN 825 if (do_ecn) { 826 /* 827 * if we have received congestion experienced segs, 828 * set ECE bit. 829 */ 830 if (tp->t_flags & TF_RCVD_CE) { 831 flags |= TH_ECE; 832 tcpstat_inc(tcps_ecn_sndece); 833 } 834 if (!(tp->t_flags & TF_DISABLE_ECN)) { 835 /* 836 * if this is a SYN seg, set ECE and CWR. 837 * set only ECE for SYN-ACK if peer supports ECN. 838 */ 839 if ((flags & (TH_SYN|TH_ACK)) == TH_SYN) 840 flags |= (TH_ECE|TH_CWR); 841 else if ((tp->t_flags & TF_ECN_PERMIT) && 842 (flags & (TH_SYN|TH_ACK)) == (TH_SYN|TH_ACK)) 843 flags |= TH_ECE; 844 } 845 /* 846 * if we have reduced the congestion window, notify 847 * the peer by setting CWR bit. 848 */ 849 if ((tp->t_flags & TF_ECN_PERMIT) && 850 (tp->t_flags & TF_SEND_CWR)) { 851 flags |= TH_CWR; 852 tp->t_flags &= ~TF_SEND_CWR; 853 tcpstat_inc(tcps_ecn_sndcwr); 854 } 855 } 856 #endif 857 th->th_flags = flags; 858 859 /* 860 * Calculate receive window. Don't shrink window, 861 * but avoid silly window syndrome. 862 */ 863 if (win < (rcv_hiwat / 4) && win < (long)tp->t_maxseg) 864 win = 0; 865 if (win > (long)TCP_MAXWIN << tp->rcv_scale) 866 win = (long)TCP_MAXWIN << tp->rcv_scale; 867 if (win < (long)(int32_t)(tp->rcv_adv - tp->rcv_nxt)) 868 win = (long)(int32_t)(tp->rcv_adv - tp->rcv_nxt); 869 if (flags & TH_RST) 870 win = 0; 871 th->th_win = htons((u_int16_t) (win>>tp->rcv_scale)); 872 if (th->th_win == 0) 873 tp->t_sndzerowin++; 874 if (SEQ_GT(tp->snd_up, tp->snd_nxt)) { 875 u_int32_t urp = tp->snd_up - tp->snd_nxt; 876 if (urp > IP_MAXPACKET) 877 urp = IP_MAXPACKET; 878 th->th_urp = htons((u_int16_t)urp); 879 th->th_flags |= TH_URG; 880 } else 881 /* 882 * If no urgent pointer to send, then we pull 883 * the urgent pointer to the left edge of the send window 884 * so that it doesn't drift into the send window on sequence 885 * number wraparound. 886 */ 887 tp->snd_up = tp->snd_una; /* drag it along */ 888 889 #ifdef TCP_SIGNATURE 890 if (tp->t_flags & TF_SIGNATURE) { 891 int iphlen; 892 union sockaddr_union src, dst; 893 struct tdb *tdb; 894 895 bzero(&src, sizeof(union sockaddr_union)); 896 bzero(&dst, sizeof(union sockaddr_union)); 897 898 switch (tp->pf) { 899 case 0: /*default to PF_INET*/ 900 case AF_INET: 901 iphlen = sizeof(struct ip); 902 src.sa.sa_len = sizeof(struct sockaddr_in); 903 src.sa.sa_family = AF_INET; 904 src.sin.sin_addr = mtod(m, struct ip *)->ip_src; 905 dst.sa.sa_len = sizeof(struct sockaddr_in); 906 dst.sa.sa_family = AF_INET; 907 dst.sin.sin_addr = mtod(m, struct ip *)->ip_dst; 908 break; 909 #ifdef INET6 910 case AF_INET6: 911 iphlen = sizeof(struct ip6_hdr); 912 src.sa.sa_len = sizeof(struct sockaddr_in6); 913 src.sa.sa_family = AF_INET6; 914 src.sin6.sin6_addr = mtod(m, struct ip6_hdr *)->ip6_src; 915 dst.sa.sa_len = sizeof(struct sockaddr_in6); 916 dst.sa.sa_family = AF_INET6; 917 dst.sin6.sin6_addr = mtod(m, struct ip6_hdr *)->ip6_dst; 918 break; 919 #endif /* INET6 */ 920 } 921 922 tdb = gettdbbysrcdst(rtable_l2(tp->t_inpcb->inp_rtableid), 923 0, &src, &dst, IPPROTO_TCP); 924 if (tdb == NULL) { 925 m_freem(m); 926 return (EPERM); 927 } 928 929 if (tcp_signature(tdb, tp->pf, m, th, iphlen, 0, 930 mtod(m, caddr_t) + hdrlen - optlen + sigoff) < 0) { 931 m_freem(m); 932 tdb_unref(tdb); 933 return (EINVAL); 934 } 935 tdb_unref(tdb); 936 } 937 #endif /* TCP_SIGNATURE */ 938 939 /* Defer checksumming until later (ip_output() or hardware) */ 940 m->m_pkthdr.csum_flags |= M_TCP_CSUM_OUT; 941 942 /* 943 * In transmit state, time the transmission and arrange for 944 * the retransmit. In persist state, just set snd_max. 945 */ 946 if (tp->t_force == 0 || TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) { 947 tcp_seq startseq = tp->snd_nxt; 948 949 /* 950 * Advance snd_nxt over sequence space of this segment. 951 */ 952 if (flags & (TH_SYN|TH_FIN)) { 953 if (flags & TH_SYN) 954 tp->snd_nxt++; 955 if (flags & TH_FIN) { 956 tp->snd_nxt++; 957 tp->t_flags |= TF_SENTFIN; 958 } 959 } 960 if (tp->sack_enable) { 961 if (sack_rxmit && (p->rxmit != tp->snd_nxt)) { 962 goto timer; 963 } 964 } 965 tp->snd_nxt += len; 966 if (SEQ_GT(tp->snd_nxt, tp->snd_max)) { 967 tp->snd_max = tp->snd_nxt; 968 /* 969 * Time this transmission if not a retransmission and 970 * not currently timing anything. 971 */ 972 if (tp->t_rtttime == 0) { 973 tp->t_rtttime = now; 974 tp->t_rtseq = startseq; 975 tcpstat_inc(tcps_segstimed); 976 } 977 } 978 979 /* 980 * Set retransmit timer if not currently set, 981 * and not doing an ack or a keep-alive probe. 982 * Initial value for retransmit timer is smoothed 983 * round-trip time + 2 * round-trip time variance. 984 * Initialize shift counter which is used for backoff 985 * of retransmit time. 986 */ 987 timer: 988 if (tp->sack_enable && sack_rxmit && 989 TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 && 990 tp->snd_nxt != tp->snd_max) { 991 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 992 if (TCP_TIMER_ISARMED(tp, TCPT_PERSIST)) { 993 TCP_TIMER_DISARM(tp, TCPT_PERSIST); 994 tp->t_rxtshift = 0; 995 } 996 } 997 998 if (TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 && 999 tp->snd_nxt != tp->snd_una) { 1000 TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur); 1001 if (TCP_TIMER_ISARMED(tp, TCPT_PERSIST)) { 1002 TCP_TIMER_DISARM(tp, TCPT_PERSIST); 1003 tp->t_rxtshift = 0; 1004 } 1005 } 1006 1007 if (len == 0 && so->so_snd.sb_cc && 1008 TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 && 1009 TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0) { 1010 /* 1011 * Avoid a situation where we do not set persist timer 1012 * after a zero window condition. For example: 1013 * 1) A -> B: packet with enough data to fill the window 1014 * 2) B -> A: ACK for #1 + new data (0 window 1015 * advertisement) 1016 * 3) A -> B: ACK for #2, 0 len packet 1017 * 1018 * In this case, A will not activate the persist timer, 1019 * because it chose to send a packet. Unless tcp_output 1020 * is called for some other reason (delayed ack timer, 1021 * another input packet from B, socket syscall), A will 1022 * not send zero window probes. 1023 * 1024 * So, if you send a 0-length packet, but there is data 1025 * in the socket buffer, and neither the rexmt or 1026 * persist timer is already set, then activate the 1027 * persist timer. 1028 */ 1029 tp->t_rxtshift = 0; 1030 tcp_setpersist(tp); 1031 } 1032 } else 1033 if (SEQ_GT(tp->snd_nxt + len, tp->snd_max)) 1034 tp->snd_max = tp->snd_nxt + len; 1035 1036 tcp_update_sndspace(tp); 1037 1038 /* 1039 * Trace. 1040 */ 1041 if (so->so_options & SO_DEBUG) 1042 tcp_trace(TA_OUTPUT, tp->t_state, tp, tp, mtod(m, caddr_t), 0, 1043 len); 1044 1045 /* 1046 * Fill in IP length and desired time to live and 1047 * send to IP level. There should be a better way 1048 * to handle ttl and tos; we could keep them in 1049 * the template, but need a way to checksum without them. 1050 */ 1051 1052 #ifdef TCP_ECN 1053 /* 1054 * if peer is ECN capable, set the ECT bit in the IP header. 1055 * but don't set ECT for a pure ack, a retransmit or a window probe. 1056 */ 1057 needect = 0; 1058 if (do_ecn && (tp->t_flags & TF_ECN_PERMIT)) { 1059 if (len == 0 || SEQ_LT(tp->snd_nxt, tp->snd_max) || 1060 (tp->t_force && len == 1)) { 1061 /* don't set ECT */ 1062 } else { 1063 needect = 1; 1064 tcpstat_inc(tcps_ecn_sndect); 1065 } 1066 } 1067 #endif 1068 1069 /* force routing table */ 1070 m->m_pkthdr.ph_rtableid = tp->t_inpcb->inp_rtableid; 1071 1072 #if NPF > 0 1073 pf_mbuf_link_inpcb(m, tp->t_inpcb); 1074 #endif 1075 1076 switch (tp->pf) { 1077 case 0: /*default to PF_INET*/ 1078 case AF_INET: 1079 { 1080 struct ip *ip; 1081 1082 ip = mtod(m, struct ip *); 1083 ip->ip_len = htons(m->m_pkthdr.len); 1084 packetlen = m->m_pkthdr.len; 1085 ip->ip_ttl = tp->t_inpcb->inp_ip.ip_ttl; 1086 ip->ip_tos = tp->t_inpcb->inp_ip.ip_tos; 1087 #ifdef TCP_ECN 1088 if (needect) 1089 ip->ip_tos |= IPTOS_ECN_ECT0; 1090 #endif 1091 } 1092 #if NSTOEPLITZ > 0 1093 m->m_pkthdr.ph_flowid = tp->t_inpcb->inp_flowid; 1094 SET(m->m_pkthdr.csum_flags, M_FLOWID); 1095 #endif 1096 error = ip_output(m, tp->t_inpcb->inp_options, 1097 &tp->t_inpcb->inp_route, 1098 (ip_mtudisc ? IP_MTUDISC : 0), NULL, 1099 &tp->t_inpcb->inp_seclevel, 0); 1100 break; 1101 #ifdef INET6 1102 case AF_INET6: 1103 { 1104 struct ip6_hdr *ip6; 1105 1106 ip6 = mtod(m, struct ip6_hdr *); 1107 ip6->ip6_plen = m->m_pkthdr.len - 1108 sizeof(struct ip6_hdr); 1109 packetlen = m->m_pkthdr.len; 1110 ip6->ip6_nxt = IPPROTO_TCP; 1111 ip6->ip6_hlim = in6_selecthlim(tp->t_inpcb); 1112 #ifdef TCP_ECN 1113 if (needect) 1114 ip6->ip6_flow |= htonl(IPTOS_ECN_ECT0 << 20); 1115 #endif 1116 } 1117 error = ip6_output(m, tp->t_inpcb->inp_outputopts6, 1118 &tp->t_inpcb->inp_route, 0, NULL, 1119 &tp->t_inpcb->inp_seclevel); 1120 break; 1121 #endif /* INET6 */ 1122 } 1123 1124 if (error) { 1125 out: 1126 if (error == ENOBUFS) { 1127 /* 1128 * If the interface queue is full, or IP cannot 1129 * get an mbuf, trigger TCP slow start. 1130 */ 1131 tp->snd_cwnd = tp->t_maxseg; 1132 return (0); 1133 } 1134 if (error == EMSGSIZE) { 1135 /* 1136 * ip_output() will have already fixed the route 1137 * for us. tcp_mtudisc() will, as its last action, 1138 * initiate retransmission, so it is important to 1139 * not do so here. 1140 */ 1141 tcp_mtudisc(tp->t_inpcb, -1); 1142 return (0); 1143 } 1144 if ((error == EHOSTUNREACH || error == ENETDOWN) && 1145 TCPS_HAVERCVDSYN(tp->t_state)) { 1146 tp->t_softerror = error; 1147 return (0); 1148 } 1149 1150 /* Restart the delayed ACK timer, if necessary. */ 1151 if (TCP_TIMER_ISARMED(tp, TCPT_DELACK)) 1152 TCP_TIMER_ARM(tp, TCPT_DELACK, tcp_delack_msecs); 1153 1154 return (error); 1155 } 1156 1157 if (packetlen > tp->t_pmtud_mtu_sent) 1158 tp->t_pmtud_mtu_sent = packetlen; 1159 1160 tcpstat_inc(tcps_sndtotal); 1161 if (TCP_TIMER_ISARMED(tp, TCPT_DELACK)) 1162 tcpstat_inc(tcps_delack); 1163 1164 /* 1165 * Data sent (as far as we can tell). 1166 * If this advertises a larger window than any other segment, 1167 * then remember the size of the advertised window. 1168 * Any pending ACK has now been sent. 1169 */ 1170 if (win > 0 && SEQ_GT(tp->rcv_nxt+win, tp->rcv_adv)) 1171 tp->rcv_adv = tp->rcv_nxt + win; 1172 tp->last_ack_sent = tp->rcv_nxt; 1173 tp->t_sndacktime = now; 1174 tp->t_flags &= ~TF_ACKNOW; 1175 TCP_TIMER_DISARM(tp, TCPT_DELACK); 1176 if (sendalot) 1177 goto again; 1178 return (0); 1179 } 1180 1181 void 1182 tcp_setpersist(struct tcpcb *tp) 1183 { 1184 int t = ((tp->t_srtt >> 2) + tp->t_rttvar) >> (1 + TCP_RTT_BASE_SHIFT); 1185 int msec; 1186 1187 if (TCP_TIMER_ISARMED(tp, TCPT_REXMT)) 1188 panic("tcp_output REXMT"); 1189 /* 1190 * Start/restart persistence timer. 1191 */ 1192 if (t < tp->t_rttmin) 1193 t = tp->t_rttmin; 1194 TCPT_RANGESET(msec, t * tcp_backoff[tp->t_rxtshift], 1195 TCPTV_PERSMIN, TCPTV_PERSMAX); 1196 TCP_TIMER_ARM(tp, TCPT_PERSIST, msec); 1197 if (tp->t_rxtshift < TCP_MAXRXTSHIFT) 1198 tp->t_rxtshift++; 1199 } 1200 1201 int 1202 tcp_chopper(struct mbuf *m0, struct mbuf_list *ml, struct ifnet *ifp, 1203 u_int mss) 1204 { 1205 struct ip *ip = NULL; 1206 #ifdef INET6 1207 struct ip6_hdr *ip6 = NULL; 1208 #endif 1209 struct tcphdr *th; 1210 int firstlen, iphlen, hlen, tlen, off; 1211 int error; 1212 1213 ml_init(ml); 1214 ml_enqueue(ml, m0); 1215 1216 if (mss == 0) { 1217 error = EINVAL; 1218 goto bad; 1219 } 1220 1221 ip = mtod(m0, struct ip *); 1222 switch (ip->ip_v) { 1223 case 4: 1224 iphlen = ip->ip_hl << 2; 1225 if (ISSET(ip->ip_off, htons(IP_OFFMASK | IP_MF)) || 1226 iphlen != sizeof(struct ip) || ip->ip_p != IPPROTO_TCP) { 1227 /* only TCP without fragment or IP option supported */ 1228 error = EPROTOTYPE; 1229 goto bad; 1230 } 1231 break; 1232 #ifdef INET6 1233 case 6: 1234 ip = NULL; 1235 ip6 = mtod(m0, struct ip6_hdr *); 1236 iphlen = sizeof(struct ip6_hdr); 1237 if (ip6->ip6_nxt != IPPROTO_TCP) { 1238 /* only TCP without IPv6 header chain supported */ 1239 error = EPROTOTYPE; 1240 goto bad; 1241 } 1242 break; 1243 #endif 1244 default: 1245 panic("%s: unknown ip version %d", __func__, ip->ip_v); 1246 } 1247 1248 tlen = m0->m_pkthdr.len; 1249 if (tlen < iphlen + sizeof(struct tcphdr)) { 1250 error = ENOPROTOOPT; 1251 goto bad; 1252 } 1253 /* IP and TCP header should be contiguous, this check is paranoia */ 1254 if (m0->m_len < iphlen + sizeof(*th)) { 1255 ml_dequeue(ml); 1256 if ((m0 = m_pullup(m0, iphlen + sizeof(*th))) == NULL) { 1257 error = ENOBUFS; 1258 goto bad; 1259 } 1260 ml_enqueue(ml, m0); 1261 } 1262 th = (struct tcphdr *)(mtod(m0, caddr_t) + iphlen); 1263 hlen = iphlen + (th->th_off << 2); 1264 if (tlen < hlen) { 1265 error = ENOPROTOOPT; 1266 goto bad; 1267 } 1268 firstlen = MIN(tlen - hlen, mss); 1269 1270 CLR(m0->m_pkthdr.csum_flags, M_TCP_TSO); 1271 1272 /* 1273 * Loop through length of payload after first segment, 1274 * make new header and copy data of each part and link onto chain. 1275 */ 1276 for (off = hlen + firstlen; off < tlen; off += mss) { 1277 struct mbuf *m; 1278 struct tcphdr *mhth; 1279 int len; 1280 1281 len = MIN(tlen - off, mss); 1282 1283 MGETHDR(m, M_DONTWAIT, MT_HEADER); 1284 if (m == NULL) { 1285 error = ENOBUFS; 1286 goto bad; 1287 } 1288 ml_enqueue(ml, m); 1289 if ((error = m_dup_pkthdr(m, m0, M_DONTWAIT)) != 0) 1290 goto bad; 1291 1292 /* IP and TCP header to the end, space for link layer header */ 1293 m->m_len = hlen; 1294 m_align(m, hlen); 1295 1296 /* copy and adjust TCP header */ 1297 mhth = (struct tcphdr *)(mtod(m, caddr_t) + iphlen); 1298 memcpy(mhth, th, hlen - iphlen); 1299 mhth->th_seq = htonl(ntohl(th->th_seq) + (off - hlen)); 1300 if (off + len < tlen) 1301 CLR(mhth->th_flags, TH_PUSH|TH_FIN); 1302 1303 /* add mbuf chain with payload */ 1304 m->m_pkthdr.len = hlen + len; 1305 if ((m->m_next = m_copym(m0, off, len, M_DONTWAIT)) == NULL) { 1306 error = ENOBUFS; 1307 goto bad; 1308 } 1309 1310 /* copy and adjust IP header, calculate checksum */ 1311 SET(m->m_pkthdr.csum_flags, M_TCP_CSUM_OUT); 1312 if (ip) { 1313 struct ip *mhip; 1314 1315 mhip = mtod(m, struct ip *); 1316 *mhip = *ip; 1317 mhip->ip_len = htons(hlen + len); 1318 mhip->ip_id = htons(ip_randomid()); 1319 in_hdr_cksum_out(m, ifp); 1320 in_proto_cksum_out(m, ifp); 1321 } 1322 #ifdef INET6 1323 if (ip6) { 1324 struct ip6_hdr *mhip6; 1325 1326 mhip6 = mtod(m, struct ip6_hdr *); 1327 *mhip6 = *ip6; 1328 mhip6->ip6_plen = htons(hlen - iphlen + len); 1329 in6_proto_cksum_out(m, ifp); 1330 } 1331 #endif 1332 } 1333 1334 /* 1335 * Update first segment by trimming what's been copied out 1336 * and updating header, then send each segment (in order). 1337 */ 1338 if (hlen + firstlen < tlen) { 1339 m_adj(m0, hlen + firstlen - tlen); 1340 CLR(th->th_flags, TH_PUSH|TH_FIN); 1341 } 1342 /* adjust IP header, calculate checksum */ 1343 SET(m0->m_pkthdr.csum_flags, M_TCP_CSUM_OUT); 1344 if (ip) { 1345 ip->ip_len = htons(m0->m_pkthdr.len); 1346 in_hdr_cksum_out(m0, ifp); 1347 in_proto_cksum_out(m0, ifp); 1348 } 1349 #ifdef INET6 1350 if (ip6) { 1351 ip6->ip6_plen = htons(m0->m_pkthdr.len - iphlen); 1352 in6_proto_cksum_out(m0, ifp); 1353 } 1354 #endif 1355 1356 tcpstat_add(tcps_outpkttso, ml_len(ml)); 1357 return 0; 1358 1359 bad: 1360 tcpstat_inc(tcps_outbadtso); 1361 ml_purge(ml); 1362 return error; 1363 } 1364 1365 int 1366 tcp_if_output_tso(struct ifnet *ifp, struct mbuf **mp, struct sockaddr *dst, 1367 struct rtentry *rt, uint32_t ifcap, u_int mtu) 1368 { 1369 struct mbuf_list ml; 1370 int error; 1371 1372 /* caller must fail later or fragment */ 1373 if (!ISSET((*mp)->m_pkthdr.csum_flags, M_TCP_TSO)) 1374 return 0; 1375 if ((*mp)->m_pkthdr.ph_mss > mtu) { 1376 CLR((*mp)->m_pkthdr.csum_flags, M_TCP_TSO); 1377 return 0; 1378 } 1379 1380 /* network interface hardware will do TSO */ 1381 if (in_ifcap_cksum(*mp, ifp, ifcap)) { 1382 if (ISSET(ifcap, IFCAP_TSOv4)) { 1383 in_hdr_cksum_out(*mp, ifp); 1384 in_proto_cksum_out(*mp, ifp); 1385 } 1386 #ifdef INET6 1387 if (ISSET(ifcap, IFCAP_TSOv6)) 1388 in6_proto_cksum_out(*mp, ifp); 1389 #endif 1390 error = ifp->if_output(ifp, *mp, dst, rt); 1391 if (!error) 1392 tcpstat_inc(tcps_outhwtso); 1393 goto done; 1394 } 1395 1396 /* as fallback do TSO in software */ 1397 if ((error = tcp_chopper(*mp, &ml, ifp, (*mp)->m_pkthdr.ph_mss)) || 1398 (error = if_output_ml(ifp, &ml, dst, rt))) 1399 goto done; 1400 tcpstat_inc(tcps_outswtso); 1401 1402 done: 1403 *mp = NULL; 1404 return error; 1405 } 1406