1/*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1995 5 * The Regents of the University of California. 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 University 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 REGENTS 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 REGENTS 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#include <sys/cdefs.h> 33#include "opt_inet.h" 34#include "opt_inet6.h" 35#include "opt_ipsec.h" 36#include "opt_kern_tls.h" 37 38#include <sys/param.h> 39#include <sys/systm.h> 40#include <sys/arb.h> 41#include <sys/domain.h> 42#ifdef TCP_HHOOK 43#include <sys/hhook.h> 44#endif 45#include <sys/kernel.h> 46#ifdef KERN_TLS 47#include <sys/ktls.h> 48#endif 49#include <sys/lock.h> 50#include <sys/mbuf.h> 51#include <sys/mutex.h> 52#include <sys/protosw.h> 53#include <sys/qmath.h> 54#include <sys/sdt.h> 55#include <sys/socket.h> 56#include <sys/socketvar.h> 57#include <sys/sysctl.h> 58#include <sys/stats.h> 59 60#include <net/if.h> 61#include <net/route.h> 62#include <net/route/nhop.h> 63#include <net/vnet.h> 64 65#include <netinet/in.h> 66#include <netinet/in_kdtrace.h> 67#include <netinet/in_systm.h> 68#include <netinet/ip.h> 69#include <netinet/in_pcb.h> 70#include <netinet/ip_var.h> 71#include <netinet/ip_options.h> 72#ifdef INET6 73#include <netinet6/in6_pcb.h> 74#include <netinet/ip6.h> 75#include <netinet6/ip6_var.h> 76#endif 77#include <netinet/tcp.h> 78#define TCPOUTFLAGS 79#include <netinet/tcp_fsm.h> 80#include <netinet/tcp_seq.h> 81#include <netinet/tcp_var.h> 82#include <netinet/tcp_log_buf.h> 83#include <netinet/tcp_syncache.h> 84#include <netinet/tcp_timer.h> 85#include <netinet/tcpip.h> 86#include <netinet/cc/cc.h> 87#include <netinet/tcp_fastopen.h> 88#ifdef TCPPCAP 89#include <netinet/tcp_pcap.h> 90#endif 91#ifdef TCP_OFFLOAD 92#include <netinet/tcp_offload.h> 93#endif 94#include <netinet/tcp_ecn.h> 95 96#include <netipsec/ipsec_support.h> 97 98#include <netinet/udp.h> 99#include <netinet/udp_var.h> 100#include <machine/in_cksum.h> 101 102#include <security/mac/mac_framework.h> 103 104VNET_DEFINE(int, path_mtu_discovery) = 1; 105SYSCTL_INT(_net_inet_tcp, OID_AUTO, path_mtu_discovery, CTLFLAG_VNET | CTLFLAG_RW, 106 &VNET_NAME(path_mtu_discovery), 1, 107 "Enable Path MTU Discovery"); 108 109VNET_DEFINE(int, tcp_do_tso) = 1; 110SYSCTL_INT(_net_inet_tcp, OID_AUTO, tso, CTLFLAG_VNET | CTLFLAG_RW, 111 &VNET_NAME(tcp_do_tso), 0, 112 "Enable TCP Segmentation Offload"); 113 114VNET_DEFINE(int, tcp_sendspace) = 1024*32; 115#define V_tcp_sendspace VNET(tcp_sendspace) 116SYSCTL_INT(_net_inet_tcp, TCPCTL_SENDSPACE, sendspace, CTLFLAG_VNET | CTLFLAG_RW, 117 &VNET_NAME(tcp_sendspace), 0, "Initial send socket buffer size"); 118 119VNET_DEFINE(int, tcp_do_autosndbuf) = 1; 120SYSCTL_INT(_net_inet_tcp, OID_AUTO, sendbuf_auto, CTLFLAG_VNET | CTLFLAG_RW, 121 &VNET_NAME(tcp_do_autosndbuf), 0, 122 "Enable automatic send buffer sizing"); 123 124VNET_DEFINE(int, tcp_autosndbuf_inc) = 8*1024; 125SYSCTL_INT(_net_inet_tcp, OID_AUTO, sendbuf_inc, CTLFLAG_VNET | CTLFLAG_RW, 126 &VNET_NAME(tcp_autosndbuf_inc), 0, 127 "Incrementor step size of automatic send buffer"); 128 129VNET_DEFINE(int, tcp_autosndbuf_max) = 2*1024*1024; 130SYSCTL_INT(_net_inet_tcp, OID_AUTO, sendbuf_max, CTLFLAG_VNET | CTLFLAG_RW, 131 &VNET_NAME(tcp_autosndbuf_max), 0, 132 "Max size of automatic send buffer"); 133 134VNET_DEFINE(int, tcp_sendbuf_auto_lowat) = 0; 135#define V_tcp_sendbuf_auto_lowat VNET(tcp_sendbuf_auto_lowat) 136SYSCTL_INT(_net_inet_tcp, OID_AUTO, sendbuf_auto_lowat, CTLFLAG_VNET | CTLFLAG_RW, 137 &VNET_NAME(tcp_sendbuf_auto_lowat), 0, 138 "Modify threshold for auto send buffer growth to account for SO_SNDLOWAT"); 139 140/* 141 * Make sure that either retransmit or persist timer is set for SYN, FIN and 142 * non-ACK. 143 */ 144#define TCP_XMIT_TIMER_ASSERT(tp, len, th_flags) \ 145 KASSERT(((len) == 0 && ((th_flags) & (TH_SYN | TH_FIN)) == 0) ||\ 146 tcp_timer_active((tp), TT_REXMT) || \ 147 tcp_timer_active((tp), TT_PERSIST), \ 148 ("neither rexmt nor persist timer is set")) 149 150#ifdef TCP_HHOOK 151/* 152 * Wrapper for the TCP established output helper hook. 153 */ 154void 155hhook_run_tcp_est_out(struct tcpcb *tp, struct tcphdr *th, 156 struct tcpopt *to, uint32_t len, int tso) 157{ 158 struct tcp_hhook_data hhook_data; 159 160 if (V_tcp_hhh[HHOOK_TCP_EST_OUT]->hhh_nhooks > 0) { 161 hhook_data.tp = tp; 162 hhook_data.th = th; 163 hhook_data.to = to; 164 hhook_data.len = len; 165 hhook_data.tso = tso; 166 167 hhook_run_hooks(V_tcp_hhh[HHOOK_TCP_EST_OUT], &hhook_data, 168 &tp->t_osd); 169 } 170} 171#endif 172 173/* 174 * CC wrapper hook functions 175 */ 176void 177cc_after_idle(struct tcpcb *tp) 178{ 179 INP_WLOCK_ASSERT(tptoinpcb(tp)); 180 181 if (CC_ALGO(tp)->after_idle != NULL) 182 CC_ALGO(tp)->after_idle(&tp->t_ccv); 183} 184 185/* 186 * Tcp output routine: figure out what should be sent and send it. 187 */ 188int 189tcp_default_output(struct tcpcb *tp) 190{ 191 struct socket *so = tptosocket(tp); 192 struct inpcb *inp = tptoinpcb(tp); 193 int32_t len; 194 uint32_t recwin, sendwin; 195 uint16_t flags; 196 int off, error = 0; /* Keep compiler happy */ 197 u_int if_hw_tsomaxsegcount = 0; 198 u_int if_hw_tsomaxsegsize = 0; 199 struct mbuf *m; 200 struct ip *ip = NULL; 201 struct tcphdr *th; 202 u_char opt[TCP_MAXOLEN]; 203 unsigned ipoptlen, optlen, hdrlen, ulen; 204#if defined(IPSEC) || defined(IPSEC_SUPPORT) 205 unsigned ipsec_optlen = 0; 206#endif 207 int idle, sendalot, curticks; 208 int sack_rxmit, sack_bytes_rxmt; 209 struct sackhole *p; 210 int tso, mtu; 211 struct tcpopt to; 212 struct udphdr *udp = NULL; 213 struct tcp_log_buffer *lgb; 214 unsigned int wanted_cookie = 0; 215 unsigned int dont_sendalot = 0; 216#if 0 217 int maxburst = TCP_MAXBURST; 218#endif 219#ifdef INET6 220 struct ip6_hdr *ip6 = NULL; 221 const bool isipv6 = (inp->inp_vflag & INP_IPV6) != 0; 222#endif 223#ifdef KERN_TLS 224 const bool hw_tls = tp->t_nic_ktls_xmit != 0; 225#else 226 const bool hw_tls = false; 227#endif 228 229 NET_EPOCH_ASSERT(); 230 INP_WLOCK_ASSERT(inp); 231 232#ifdef TCP_OFFLOAD 233 if (tp->t_flags & TF_TOE) 234 return (tcp_offload_output(tp)); 235#endif 236 237 /* 238 * For TFO connections in SYN_SENT or SYN_RECEIVED, 239 * only allow the initial SYN or SYN|ACK and those sent 240 * by the retransmit timer. 241 */ 242 if ((tp->t_flags & TF_FASTOPEN) && 243 ((tp->t_state == TCPS_SYN_SENT) || 244 (tp->t_state == TCPS_SYN_RECEIVED)) && 245 SEQ_GT(tp->snd_max, tp->snd_una) && /* SYN or SYN|ACK sent */ 246 (tp->snd_nxt != tp->snd_una)) /* not a retransmit */ 247 return (0); 248 249 /* 250 * Determine length of data that should be transmitted, 251 * and flags that will be used. 252 * If there is some data or critical controls (SYN, RST) 253 * to send, then transmit; otherwise, investigate further. 254 */ 255 idle = (tp->t_flags & TF_LASTIDLE) || (tp->snd_max == tp->snd_una); 256 if (idle && (((ticks - tp->t_rcvtime) >= tp->t_rxtcur) || 257 (tp->t_sndtime && ((ticks - tp->t_sndtime) >= tp->t_rxtcur)))) 258 cc_after_idle(tp); 259 tp->t_flags &= ~TF_LASTIDLE; 260 if (idle) { 261 if (tp->t_flags & TF_MORETOCOME) { 262 tp->t_flags |= TF_LASTIDLE; 263 idle = 0; 264 } 265 } 266again: 267 /* 268 * If we've recently taken a timeout, snd_max will be greater than 269 * snd_nxt. There may be SACK information that allows us to avoid 270 * resending already delivered data. Adjust snd_nxt accordingly. 271 */ 272 if ((tp->t_flags & TF_SACK_PERMIT) && 273 SEQ_LT(tp->snd_nxt, tp->snd_max)) 274 tcp_sack_adjust(tp); 275 sendalot = 0; 276 tso = 0; 277 mtu = 0; 278 off = tp->snd_nxt - tp->snd_una; 279 sendwin = min(tp->snd_wnd, tp->snd_cwnd); 280 281 flags = tcp_outflags[tp->t_state]; 282 /* 283 * Send any SACK-generated retransmissions. If we're explicitly trying 284 * to send out new data (when sendalot is 1), bypass this function. 285 * If we retransmit in fast recovery mode, decrement snd_cwnd, since 286 * we're replacing a (future) new transmission with a retransmission 287 * now, and we previously incremented snd_cwnd in tcp_input(). 288 */ 289 /* 290 * Still in sack recovery , reset rxmit flag to zero. 291 */ 292 sack_rxmit = 0; 293 sack_bytes_rxmt = 0; 294 len = 0; 295 p = NULL; 296 if ((tp->t_flags & TF_SACK_PERMIT) && IN_FASTRECOVERY(tp->t_flags) && 297 (p = tcp_sack_output(tp, &sack_bytes_rxmt))) { 298 uint32_t cwin; 299 300 cwin = 301 imax(min(tp->snd_wnd, tp->snd_cwnd) - sack_bytes_rxmt, 0); 302 /* Do not retransmit SACK segments beyond snd_recover */ 303 if (SEQ_GT(p->end, tp->snd_recover)) { 304 /* 305 * (At least) part of sack hole extends beyond 306 * snd_recover. Check to see if we can rexmit data 307 * for this hole. 308 */ 309 if (SEQ_GEQ(p->rxmit, tp->snd_recover)) { 310 /* 311 * Can't rexmit any more data for this hole. 312 * That data will be rexmitted in the next 313 * sack recovery episode, when snd_recover 314 * moves past p->rxmit. 315 */ 316 p = NULL; 317 goto after_sack_rexmit; 318 } else { 319 /* Can rexmit part of the current hole */ 320 len = ((int32_t)ulmin(cwin, 321 SEQ_SUB(tp->snd_recover, p->rxmit))); 322 } 323 } else { 324 len = ((int32_t)ulmin(cwin, 325 SEQ_SUB(p->end, p->rxmit))); 326 } 327 if (len > 0) { 328 off = SEQ_SUB(p->rxmit, tp->snd_una); 329 KASSERT(off >= 0,("%s: sack block to the left of una : %d", 330 __func__, off)); 331 sack_rxmit = 1; 332 sendalot = 1; 333 } 334 } 335after_sack_rexmit: 336 /* 337 * Get standard flags, and add SYN or FIN if requested by 'hidden' 338 * state flags. 339 */ 340 if (tp->t_flags & TF_NEEDFIN) 341 flags |= TH_FIN; 342 if (tp->t_flags & TF_NEEDSYN) 343 flags |= TH_SYN; 344 345 SOCKBUF_LOCK(&so->so_snd); 346 /* 347 * If in persist timeout with window of 0, send 1 byte. 348 * Otherwise, if window is small but nonzero 349 * and timer expired, we will send what we can 350 * and go to transmit state. 351 */ 352 if (tp->t_flags & TF_FORCEDATA) { 353 if (sendwin == 0) { 354 /* 355 * If we still have some data to send, then 356 * clear the FIN bit. Usually this would 357 * happen below when it realizes that we 358 * aren't sending all the data. However, 359 * if we have exactly 1 byte of unsent data, 360 * then it won't clear the FIN bit below, 361 * and if we are in persist state, we wind 362 * up sending the packet without recording 363 * that we sent the FIN bit. 364 * 365 * We can't just blindly clear the FIN bit, 366 * because if we don't have any more data 367 * to send then the probe will be the FIN 368 * itself. 369 */ 370 if (off < sbused(&so->so_snd)) 371 flags &= ~TH_FIN; 372 sendwin = 1; 373 } else { 374 tcp_timer_activate(tp, TT_PERSIST, 0); 375 tp->t_rxtshift = 0; 376 } 377 } 378 379 /* 380 * If snd_nxt == snd_max and we have transmitted a FIN, the 381 * offset will be > 0 even if so_snd.sb_cc is 0, resulting in 382 * a negative length. This can also occur when TCP opens up 383 * its congestion window while receiving additional duplicate 384 * acks after fast-retransmit because TCP will reset snd_nxt 385 * to snd_max after the fast-retransmit. 386 * 387 * In the normal retransmit-FIN-only case, however, snd_nxt will 388 * be set to snd_una, the offset will be 0, and the length may 389 * wind up 0. 390 * 391 * If sack_rxmit is true we are retransmitting from the scoreboard 392 * in which case len is already set. 393 */ 394 if (sack_rxmit == 0) { 395 if (sack_bytes_rxmt == 0) { 396 len = ((int32_t)min(sbavail(&so->so_snd), sendwin) - 397 off); 398 } else { 399 int32_t cwin; 400 401 /* 402 * We are inside of a SACK recovery episode and are 403 * sending new data, having retransmitted all the 404 * data possible in the scoreboard. 405 */ 406 len = ((int32_t)min(sbavail(&so->so_snd), tp->snd_wnd) - 407 off); 408 /* 409 * Don't remove this (len > 0) check ! 410 * We explicitly check for len > 0 here (although it 411 * isn't really necessary), to work around a gcc 412 * optimization issue - to force gcc to compute 413 * len above. Without this check, the computation 414 * of len is bungled by the optimizer. 415 */ 416 if (len > 0) { 417 cwin = tp->snd_cwnd - imax(0, (int32_t) 418 (tp->snd_nxt - tp->snd_recover)) - 419 sack_bytes_rxmt; 420 if (cwin < 0) 421 cwin = 0; 422 len = imin(len, cwin); 423 } 424 } 425 } 426 427 /* 428 * Lop off SYN bit if it has already been sent. However, if this 429 * is SYN-SENT state and if segment contains data and if we don't 430 * know that foreign host supports TAO, suppress sending segment. 431 */ 432 if ((flags & TH_SYN) && SEQ_GT(tp->snd_nxt, tp->snd_una)) { 433 if (tp->t_state != TCPS_SYN_RECEIVED) 434 flags &= ~TH_SYN; 435 /* 436 * When sending additional segments following a TFO SYN|ACK, 437 * do not include the SYN bit. 438 */ 439 if ((tp->t_flags & TF_FASTOPEN) && 440 (tp->t_state == TCPS_SYN_RECEIVED)) 441 flags &= ~TH_SYN; 442 off--, len++; 443 } 444 445 /* 446 * Be careful not to send data and/or FIN on SYN segments. 447 * This measure is needed to prevent interoperability problems 448 * with not fully conformant TCP implementations. 449 */ 450 if ((flags & TH_SYN) && (tp->t_flags & TF_NOOPT)) { 451 len = 0; 452 flags &= ~TH_FIN; 453 } 454 455 /* 456 * On TFO sockets, ensure no data is sent in the following cases: 457 * 458 * - When retransmitting SYN|ACK on a passively-created socket 459 * 460 * - When retransmitting SYN on an actively created socket 461 * 462 * - When sending a zero-length cookie (cookie request) on an 463 * actively created socket 464 * 465 * - When the socket is in the CLOSED state (RST is being sent) 466 */ 467 if ((tp->t_flags & TF_FASTOPEN) && 468 (((flags & TH_SYN) && (tp->t_rxtshift > 0)) || 469 ((tp->t_state == TCPS_SYN_SENT) && 470 (tp->t_tfo_client_cookie_len == 0)) || 471 (flags & TH_RST))) 472 len = 0; 473 474 /* Without fast-open there should never be data sent on a SYN. */ 475 if ((flags & TH_SYN) && !(tp->t_flags & TF_FASTOPEN)) { 476 len = 0; 477 } 478 479 if (len <= 0) { 480 /* 481 * If FIN has been sent but not acked, 482 * but we haven't been called to retransmit, 483 * len will be < 0. Otherwise, window shrank 484 * after we sent into it. If window shrank to 0, 485 * cancel pending retransmit, pull snd_nxt back 486 * to (closed) window, and set the persist timer 487 * if it isn't already going. If the window didn't 488 * close completely, just wait for an ACK. 489 * 490 * We also do a general check here to ensure that 491 * we will set the persist timer when we have data 492 * to send, but a 0-byte window. This makes sure 493 * the persist timer is set even if the packet 494 * hits one of the "goto send" lines below. 495 */ 496 len = 0; 497 if ((sendwin == 0) && (TCPS_HAVEESTABLISHED(tp->t_state)) && 498 (off < (int) sbavail(&so->so_snd)) && 499 !tcp_timer_active(tp, TT_PERSIST)) { 500 tcp_timer_activate(tp, TT_REXMT, 0); 501 tp->t_rxtshift = 0; 502 tp->snd_nxt = tp->snd_una; 503 if (!tcp_timer_active(tp, TT_PERSIST)) 504 tcp_setpersist(tp); 505 } 506 } 507 508 /* len will be >= 0 after this point. */ 509 KASSERT(len >= 0, ("[%s:%d]: len < 0", __func__, __LINE__)); 510 511 tcp_sndbuf_autoscale(tp, so, sendwin); 512 513 /* 514 * Decide if we can use TCP Segmentation Offloading (if supported by 515 * hardware). 516 * 517 * TSO may only be used if we are in a pure bulk sending state. The 518 * presence of TCP-MD5, SACK retransmits, SACK advertizements and 519 * IP options prevent using TSO. With TSO the TCP header is the same 520 * (except for the sequence number) for all generated packets. This 521 * makes it impossible to transmit any options which vary per generated 522 * segment or packet. 523 * 524 * IPv4 handling has a clear separation of ip options and ip header 525 * flags while IPv6 combines both in in6p_outputopts. ip6_optlen() does 526 * the right thing below to provide length of just ip options and thus 527 * checking for ipoptlen is enough to decide if ip options are present. 528 */ 529#if defined(IPSEC) || defined(IPSEC_SUPPORT) 530 /* 531 * Pre-calculate here as we save another lookup into the darknesses 532 * of IPsec that way and can actually decide if TSO is ok. 533 */ 534#ifdef INET6 535 if (isipv6 && IPSEC_ENABLED(ipv6)) 536 ipsec_optlen = IPSEC_HDRSIZE(ipv6, inp); 537#ifdef INET 538 else 539#endif 540#endif /* INET6 */ 541#ifdef INET 542 if (IPSEC_ENABLED(ipv4)) 543 ipsec_optlen = IPSEC_HDRSIZE(ipv4, inp); 544#endif /* INET */ 545#endif /* IPSEC */ 546#ifdef INET6 547 if (isipv6) 548 ipoptlen = ip6_optlen(inp); 549 else 550#endif 551 if (inp->inp_options) 552 ipoptlen = inp->inp_options->m_len - 553 offsetof(struct ipoption, ipopt_list); 554 else 555 ipoptlen = 0; 556#if defined(IPSEC) || defined(IPSEC_SUPPORT) 557 ipoptlen += ipsec_optlen; 558#endif 559 560 if ((tp->t_flags & TF_TSO) && V_tcp_do_tso && len > tp->t_maxseg && 561 (tp->t_port == 0) && 562 ((tp->t_flags & TF_SIGNATURE) == 0) && 563 tp->rcv_numsacks == 0 && ((sack_rxmit == 0) || V_tcp_sack_tso) && 564 ipoptlen == 0 && !(flags & TH_SYN)) 565 tso = 1; 566 567 if (SEQ_LT((sack_rxmit ? p->rxmit : tp->snd_nxt) + len, 568 tp->snd_una + sbused(&so->so_snd))) { 569 flags &= ~TH_FIN; 570 } 571 572 recwin = lmin(lmax(sbspace(&so->so_rcv), 0), 573 (long)TCP_MAXWIN << tp->rcv_scale); 574 575 /* 576 * Sender silly window avoidance. We transmit under the following 577 * conditions when len is non-zero: 578 * 579 * - We have a full segment (or more with TSO) 580 * - This is the last buffer in a write()/send() and we are 581 * either idle or running NODELAY 582 * - we've timed out (e.g. persist timer) 583 * - we have more then 1/2 the maximum send window's worth of 584 * data (receiver may be limited the window size) 585 * - we need to retransmit 586 */ 587 if (len) { 588 if (len >= tp->t_maxseg) 589 goto send; 590 /* 591 * As the TCP header options are now 592 * considered when setting up the initial 593 * window, we would not send the last segment 594 * if we skip considering the option length here. 595 * Note: this may not work when tcp headers change 596 * very dynamically in the future. 597 */ 598 if ((((tp->t_flags & TF_SIGNATURE) ? 599 PADTCPOLEN(TCPOLEN_SIGNATURE) : 0) + 600 ((tp->t_flags & TF_RCVD_TSTMP) ? 601 PADTCPOLEN(TCPOLEN_TIMESTAMP) : 0) + 602 len) >= tp->t_maxseg) 603 goto send; 604 /* 605 * NOTE! on localhost connections an 'ack' from the remote 606 * end may occur synchronously with the output and cause 607 * us to flush a buffer queued with moretocome. XXX 608 * 609 * note: the len + off check is almost certainly unnecessary. 610 */ 611 if (!(tp->t_flags & TF_MORETOCOME) && /* normal case */ 612 (idle || (tp->t_flags & TF_NODELAY)) && 613 (uint32_t)len + (uint32_t)off >= sbavail(&so->so_snd) && 614 (tp->t_flags & TF_NOPUSH) == 0) { 615 goto send; 616 } 617 if (tp->t_flags & TF_FORCEDATA) /* typ. timeout case */ 618 goto send; 619 if (len >= tp->max_sndwnd / 2 && tp->max_sndwnd > 0) 620 goto send; 621 if (SEQ_LT(tp->snd_nxt, tp->snd_max)) /* retransmit case */ 622 goto send; 623 if (sack_rxmit) 624 goto send; 625 } 626 627 /* 628 * Sending of standalone window updates. 629 * 630 * Window updates are important when we close our window due to a 631 * full socket buffer and are opening it again after the application 632 * reads data from it. Once the window has opened again and the 633 * remote end starts to send again the ACK clock takes over and 634 * provides the most current window information. 635 * 636 * We must avoid the silly window syndrome whereas every read 637 * from the receive buffer, no matter how small, causes a window 638 * update to be sent. We also should avoid sending a flurry of 639 * window updates when the socket buffer had queued a lot of data 640 * and the application is doing small reads. 641 * 642 * Prevent a flurry of pointless window updates by only sending 643 * an update when we can increase the advertized window by more 644 * than 1/4th of the socket buffer capacity. When the buffer is 645 * getting full or is very small be more aggressive and send an 646 * update whenever we can increase by two mss sized segments. 647 * In all other situations the ACK's to new incoming data will 648 * carry further window increases. 649 * 650 * Don't send an independent window update if a delayed 651 * ACK is pending (it will get piggy-backed on it) or the 652 * remote side already has done a half-close and won't send 653 * more data. 654 */ 655 if (recwin > 0 && !(tp->t_flags & TF_NEEDSYN) && 656 !(tp->t_flags & TF_DELACK) && 657 !TCPS_HAVERCVDFIN(tp->t_state)) { 658 /* 659 * "adv" is the amount we could increase the window, 660 * taking into account that we are limited by 661 * TCP_MAXWIN << tp->rcv_scale. 662 */ 663 int32_t adv; 664 int oldwin; 665 666 adv = recwin; 667 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt)) { 668 oldwin = (tp->rcv_adv - tp->rcv_nxt); 669 if (adv > oldwin) 670 adv -= oldwin; 671 else 672 adv = 0; 673 } else 674 oldwin = 0; 675 676 /* 677 * If the new window size ends up being the same as or less 678 * than the old size when it is scaled, then don't force 679 * a window update. 680 */ 681 if (oldwin >> tp->rcv_scale >= (adv + oldwin) >> tp->rcv_scale) 682 goto dontupdate; 683 684 if (adv >= (int32_t)(2 * tp->t_maxseg) && 685 (adv >= (int32_t)(so->so_rcv.sb_hiwat / 4) || 686 recwin <= (so->so_rcv.sb_hiwat / 8) || 687 so->so_rcv.sb_hiwat <= 8 * tp->t_maxseg || 688 adv >= TCP_MAXWIN << tp->rcv_scale)) 689 goto send; 690 if (2 * adv >= (int32_t)so->so_rcv.sb_hiwat) 691 goto send; 692 } 693dontupdate: 694 695 /* 696 * Send if we owe the peer an ACK, RST, SYN, or urgent data. ACKNOW 697 * is also a catch-all for the retransmit timer timeout case. 698 */ 699 if (tp->t_flags & TF_ACKNOW) 700 goto send; 701 if ((flags & TH_RST) || 702 ((flags & TH_SYN) && (tp->t_flags & TF_NEEDSYN) == 0)) 703 goto send; 704 if (SEQ_GT(tp->snd_up, tp->snd_una)) 705 goto send; 706 /* 707 * If our state indicates that FIN should be sent 708 * and we have not yet done so, then we need to send. 709 */ 710 if (flags & TH_FIN && 711 ((tp->t_flags & TF_SENTFIN) == 0 || tp->snd_nxt == tp->snd_una)) 712 goto send; 713 /* 714 * In SACK, it is possible for tcp_output to fail to send a segment 715 * after the retransmission timer has been turned off. Make sure 716 * that the retransmission timer is set. 717 */ 718 if ((tp->t_flags & TF_SACK_PERMIT) && 719 SEQ_GT(tp->snd_max, tp->snd_una) && 720 !tcp_timer_active(tp, TT_REXMT) && 721 !tcp_timer_active(tp, TT_PERSIST)) { 722 tcp_timer_activate(tp, TT_REXMT, TP_RXTCUR(tp)); 723 goto just_return; 724 } 725 /* 726 * TCP window updates are not reliable, rather a polling protocol 727 * using ``persist'' packets is used to insure receipt of window 728 * updates. The three ``states'' for the output side are: 729 * idle not doing retransmits or persists 730 * persisting to move a small or zero window 731 * (re)transmitting and thereby not persisting 732 * 733 * tcp_timer_active(tp, TT_PERSIST) 734 * is true when we are in persist state. 735 * (tp->t_flags & TF_FORCEDATA) 736 * is set when we are called to send a persist packet. 737 * tcp_timer_active(tp, TT_REXMT) 738 * is set when we are retransmitting 739 * The output side is idle when both timers are zero. 740 * 741 * If send window is too small, there is data to transmit, and no 742 * retransmit or persist is pending, then go to persist state. 743 * If nothing happens soon, send when timer expires: 744 * if window is nonzero, transmit what we can, 745 * otherwise force out a byte. 746 */ 747 if (sbavail(&so->so_snd) && !tcp_timer_active(tp, TT_REXMT) && 748 !tcp_timer_active(tp, TT_PERSIST)) { 749 tp->t_rxtshift = 0; 750 tcp_setpersist(tp); 751 } 752 753 /* 754 * No reason to send a segment, just return. 755 */ 756just_return: 757 SOCKBUF_UNLOCK(&so->so_snd); 758 return (0); 759 760send: 761 SOCKBUF_LOCK_ASSERT(&so->so_snd); 762 if (len > 0) { 763 if (len >= tp->t_maxseg) 764 tp->t_flags2 |= TF2_PLPMTU_MAXSEGSNT; 765 else 766 tp->t_flags2 &= ~TF2_PLPMTU_MAXSEGSNT; 767 } 768 /* 769 * Before ESTABLISHED, force sending of initial options 770 * unless TCP set not to do any options. 771 * NOTE: we assume that the IP/TCP header plus TCP options 772 * always fit in a single mbuf, leaving room for a maximum 773 * link header, i.e. 774 * max_linkhdr + sizeof (struct tcpiphdr) + optlen <= MCLBYTES 775 */ 776 optlen = 0; 777#ifdef INET6 778 if (isipv6) 779 hdrlen = sizeof (struct ip6_hdr) + sizeof (struct tcphdr); 780 else 781#endif 782 hdrlen = sizeof (struct tcpiphdr); 783 784 if (flags & TH_SYN) { 785 tp->snd_nxt = tp->iss; 786 } 787 788 /* 789 * Compute options for segment. 790 * We only have to care about SYN and established connection 791 * segments. Options for SYN-ACK segments are handled in TCP 792 * syncache. 793 */ 794 to.to_flags = 0; 795 if ((tp->t_flags & TF_NOOPT) == 0) { 796 /* Maximum segment size. */ 797 if (flags & TH_SYN) { 798 to.to_mss = tcp_mssopt(&inp->inp_inc); 799 if (tp->t_port) 800 to.to_mss -= V_tcp_udp_tunneling_overhead; 801 to.to_flags |= TOF_MSS; 802 803 /* 804 * On SYN or SYN|ACK transmits on TFO connections, 805 * only include the TFO option if it is not a 806 * retransmit, as the presence of the TFO option may 807 * have caused the original SYN or SYN|ACK to have 808 * been dropped by a middlebox. 809 */ 810 if ((tp->t_flags & TF_FASTOPEN) && 811 (tp->t_rxtshift == 0)) { 812 if (tp->t_state == TCPS_SYN_RECEIVED) { 813 to.to_tfo_len = TCP_FASTOPEN_COOKIE_LEN; 814 to.to_tfo_cookie = 815 (u_int8_t *)&tp->t_tfo_cookie.server; 816 to.to_flags |= TOF_FASTOPEN; 817 wanted_cookie = 1; 818 } else if (tp->t_state == TCPS_SYN_SENT) { 819 to.to_tfo_len = 820 tp->t_tfo_client_cookie_len; 821 to.to_tfo_cookie = 822 tp->t_tfo_cookie.client; 823 to.to_flags |= TOF_FASTOPEN; 824 wanted_cookie = 1; 825 /* 826 * If we wind up having more data to 827 * send with the SYN than can fit in 828 * one segment, don't send any more 829 * until the SYN|ACK comes back from 830 * the other end. 831 */ 832 dont_sendalot = 1; 833 } 834 } 835 } 836 /* Window scaling. */ 837 if ((flags & TH_SYN) && (tp->t_flags & TF_REQ_SCALE)) { 838 to.to_wscale = tp->request_r_scale; 839 to.to_flags |= TOF_SCALE; 840 } 841 /* Timestamps. */ 842 if ((tp->t_flags & TF_RCVD_TSTMP) || 843 ((flags & TH_SYN) && (tp->t_flags & TF_REQ_TSTMP))) { 844 curticks = tcp_ts_getticks(); 845 to.to_tsval = curticks + tp->ts_offset; 846 to.to_tsecr = tp->ts_recent; 847 to.to_flags |= TOF_TS; 848 if (tp->t_rxtshift == 1) 849 tp->t_badrxtwin = curticks; 850 } 851 852 /* Set receive buffer autosizing timestamp. */ 853 if (tp->rfbuf_ts == 0 && 854 (so->so_rcv.sb_flags & SB_AUTOSIZE)) 855 tp->rfbuf_ts = tcp_ts_getticks(); 856 857 /* Selective ACK's. */ 858 if (tp->t_flags & TF_SACK_PERMIT) { 859 if (flags & TH_SYN) 860 to.to_flags |= TOF_SACKPERM; 861 else if (TCPS_HAVEESTABLISHED(tp->t_state) && 862 tp->rcv_numsacks > 0) { 863 to.to_flags |= TOF_SACK; 864 to.to_nsacks = tp->rcv_numsacks; 865 to.to_sacks = (u_char *)tp->sackblks; 866 } 867 } 868#if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 869 /* TCP-MD5 (RFC2385). */ 870 /* 871 * Check that TCP_MD5SIG is enabled in tcpcb to 872 * account the size needed to set this TCP option. 873 */ 874 if (tp->t_flags & TF_SIGNATURE) 875 to.to_flags |= TOF_SIGNATURE; 876#endif /* TCP_SIGNATURE */ 877 878 /* Processing the options. */ 879 hdrlen += optlen = tcp_addoptions(&to, opt); 880 /* 881 * If we wanted a TFO option to be added, but it was unable 882 * to fit, ensure no data is sent. 883 */ 884 if ((tp->t_flags & TF_FASTOPEN) && wanted_cookie && 885 !(to.to_flags & TOF_FASTOPEN)) 886 len = 0; 887 } 888 if (tp->t_port) { 889 if (V_tcp_udp_tunneling_port == 0) { 890 /* The port was removed?? */ 891 SOCKBUF_UNLOCK(&so->so_snd); 892 return (EHOSTUNREACH); 893 } 894 hdrlen += sizeof(struct udphdr); 895 } 896 /* 897 * Adjust data length if insertion of options will 898 * bump the packet length beyond the t_maxseg length. 899 * Clear the FIN bit because we cut off the tail of 900 * the segment. 901 */ 902 if (len + optlen + ipoptlen > tp->t_maxseg) { 903 flags &= ~TH_FIN; 904 905 if (tso) { 906 u_int if_hw_tsomax; 907 u_int moff; 908 int max_len; 909 910 /* extract TSO information */ 911 if_hw_tsomax = tp->t_tsomax; 912 if_hw_tsomaxsegcount = tp->t_tsomaxsegcount; 913 if_hw_tsomaxsegsize = tp->t_tsomaxsegsize; 914 915 /* 916 * Limit a TSO burst to prevent it from 917 * overflowing or exceeding the maximum length 918 * allowed by the network interface: 919 */ 920 KASSERT(ipoptlen == 0, 921 ("%s: TSO can't do IP options", __func__)); 922 923 /* 924 * Check if we should limit by maximum payload 925 * length: 926 */ 927 if (if_hw_tsomax != 0) { 928 /* compute maximum TSO length */ 929 max_len = (if_hw_tsomax - hdrlen - 930 max_linkhdr); 931 if (max_len <= 0) { 932 len = 0; 933 } else if (len > max_len) { 934 sendalot = 1; 935 len = max_len; 936 } 937 } 938 939 /* 940 * Prevent the last segment from being 941 * fractional unless the send sockbuf can be 942 * emptied: 943 */ 944 max_len = (tp->t_maxseg - optlen); 945 if (((uint32_t)off + (uint32_t)len) < 946 sbavail(&so->so_snd)) { 947 moff = len % max_len; 948 if (moff != 0) { 949 len -= moff; 950 sendalot = 1; 951 } 952 } 953 954 /* 955 * In case there are too many small fragments 956 * don't use TSO: 957 */ 958 if (len <= max_len) { 959 len = max_len; 960 sendalot = 1; 961 tso = 0; 962 } 963 964 /* 965 * Send the FIN in a separate segment 966 * after the bulk sending is done. 967 * We don't trust the TSO implementations 968 * to clear the FIN flag on all but the 969 * last segment. 970 */ 971 if (tp->t_flags & TF_NEEDFIN) 972 sendalot = 1; 973 } else { 974 if (optlen + ipoptlen >= tp->t_maxseg) { 975 /* 976 * Since we don't have enough space to put 977 * the IP header chain and the TCP header in 978 * one packet as required by RFC 7112, don't 979 * send it. Also ensure that at least one 980 * byte of the payload can be put into the 981 * TCP segment. 982 */ 983 SOCKBUF_UNLOCK(&so->so_snd); 984 error = EMSGSIZE; 985 sack_rxmit = 0; 986 goto out; 987 } 988 len = tp->t_maxseg - optlen - ipoptlen; 989 sendalot = 1; 990 if (dont_sendalot) 991 sendalot = 0; 992 } 993 } else 994 tso = 0; 995 996 KASSERT(len + hdrlen + ipoptlen <= IP_MAXPACKET, 997 ("%s: len > IP_MAXPACKET", __func__)); 998 999/*#ifdef DIAGNOSTIC*/ 1000#ifdef INET6 1001 if (max_linkhdr + hdrlen > MCLBYTES) 1002#else 1003 if (max_linkhdr + hdrlen > MHLEN) 1004#endif 1005 panic("tcphdr too big"); 1006/*#endif*/ 1007 1008 /* 1009 * This KASSERT is here to catch edge cases at a well defined place. 1010 * Before, those had triggered (random) panic conditions further down. 1011 */ 1012 KASSERT(len >= 0, ("[%s:%d]: len < 0", __func__, __LINE__)); 1013 1014 /* 1015 * Grab a header mbuf, attaching a copy of data to 1016 * be transmitted, and initialize the header from 1017 * the template for sends on this connection. 1018 */ 1019 if (len) { 1020 struct mbuf *mb; 1021 struct sockbuf *msb; 1022 u_int moff; 1023 1024 if ((tp->t_flags & TF_FORCEDATA) && len == 1) { 1025 TCPSTAT_INC(tcps_sndprobe); 1026#ifdef STATS 1027 if (SEQ_LT(tp->snd_nxt, tp->snd_max)) 1028 stats_voi_update_abs_u32(tp->t_stats, 1029 VOI_TCP_RETXPB, len); 1030 else 1031 stats_voi_update_abs_u64(tp->t_stats, 1032 VOI_TCP_TXPB, len); 1033#endif /* STATS */ 1034 } else if (SEQ_LT(tp->snd_nxt, tp->snd_max) || sack_rxmit) { 1035 tp->t_sndrexmitpack++; 1036 TCPSTAT_INC(tcps_sndrexmitpack); 1037 TCPSTAT_ADD(tcps_sndrexmitbyte, len); 1038 if (sack_rxmit) { 1039 TCPSTAT_INC(tcps_sack_rexmits); 1040 if (tso) { 1041 TCPSTAT_INC(tcps_sack_rexmits_tso); 1042 } 1043 TCPSTAT_ADD(tcps_sack_rexmit_bytes, len); 1044 } 1045#ifdef STATS 1046 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_RETXPB, 1047 len); 1048#endif /* STATS */ 1049 } else { 1050 TCPSTAT_INC(tcps_sndpack); 1051 TCPSTAT_ADD(tcps_sndbyte, len); 1052#ifdef STATS 1053 stats_voi_update_abs_u64(tp->t_stats, VOI_TCP_TXPB, 1054 len); 1055#endif /* STATS */ 1056 } 1057#ifdef INET6 1058 if (MHLEN < hdrlen + max_linkhdr) 1059 m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR); 1060 else 1061#endif 1062 m = m_gethdr(M_NOWAIT, MT_DATA); 1063 1064 if (m == NULL) { 1065 SOCKBUF_UNLOCK(&so->so_snd); 1066 error = ENOBUFS; 1067 sack_rxmit = 0; 1068 goto out; 1069 } 1070 1071 m->m_data += max_linkhdr; 1072 m->m_len = hdrlen; 1073 1074 /* 1075 * Start the m_copy functions from the closest mbuf 1076 * to the offset in the socket buffer chain. 1077 */ 1078 mb = sbsndptr_noadv(&so->so_snd, off, &moff); 1079 if (len <= MHLEN - hdrlen - max_linkhdr && !hw_tls) { 1080 m_copydata(mb, moff, len, 1081 mtod(m, caddr_t) + hdrlen); 1082 if (SEQ_LT(tp->snd_nxt, tp->snd_max)) 1083 sbsndptr_adv(&so->so_snd, mb, len); 1084 m->m_len += len; 1085 } else { 1086 if (SEQ_LT(tp->snd_nxt, tp->snd_max)) 1087 msb = NULL; 1088 else 1089 msb = &so->so_snd; 1090 m->m_next = tcp_m_copym(mb, moff, 1091 &len, if_hw_tsomaxsegcount, 1092 if_hw_tsomaxsegsize, msb, hw_tls); 1093 if (len <= (tp->t_maxseg - optlen)) { 1094 /* 1095 * Must have ran out of mbufs for the copy 1096 * shorten it to no longer need tso. Lets 1097 * not put on sendalot since we are low on 1098 * mbufs. 1099 */ 1100 tso = 0; 1101 } 1102 if (m->m_next == NULL) { 1103 SOCKBUF_UNLOCK(&so->so_snd); 1104 (void) m_free(m); 1105 error = ENOBUFS; 1106 sack_rxmit = 0; 1107 goto out; 1108 } 1109 } 1110 1111 /* 1112 * If we're sending everything we've got, set PUSH. 1113 * (This will keep happy those implementations which only 1114 * give data to the user when a buffer fills or 1115 * a PUSH comes in.) 1116 */ 1117 if (((uint32_t)off + (uint32_t)len == sbused(&so->so_snd)) && 1118 !(flags & TH_SYN)) 1119 flags |= TH_PUSH; 1120 SOCKBUF_UNLOCK(&so->so_snd); 1121 } else { 1122 SOCKBUF_UNLOCK(&so->so_snd); 1123 if (tp->t_flags & TF_ACKNOW) 1124 TCPSTAT_INC(tcps_sndacks); 1125 else if (flags & (TH_SYN|TH_FIN|TH_RST)) 1126 TCPSTAT_INC(tcps_sndctrl); 1127 else if (SEQ_GT(tp->snd_up, tp->snd_una)) 1128 TCPSTAT_INC(tcps_sndurg); 1129 else 1130 TCPSTAT_INC(tcps_sndwinup); 1131 1132 m = m_gethdr(M_NOWAIT, MT_DATA); 1133 if (m == NULL) { 1134 error = ENOBUFS; 1135 sack_rxmit = 0; 1136 goto out; 1137 } 1138#ifdef INET6 1139 if (isipv6 && (MHLEN < hdrlen + max_linkhdr) && 1140 MHLEN >= hdrlen) { 1141 M_ALIGN(m, hdrlen); 1142 } else 1143#endif 1144 m->m_data += max_linkhdr; 1145 m->m_len = hdrlen; 1146 } 1147 SOCKBUF_UNLOCK_ASSERT(&so->so_snd); 1148 m->m_pkthdr.rcvif = (struct ifnet *)0; 1149#ifdef MAC 1150 mac_inpcb_create_mbuf(inp, m); 1151#endif 1152#ifdef INET6 1153 if (isipv6) { 1154 ip6 = mtod(m, struct ip6_hdr *); 1155 if (tp->t_port) { 1156 udp = (struct udphdr *)((caddr_t)ip6 + sizeof(struct ip6_hdr)); 1157 udp->uh_sport = htons(V_tcp_udp_tunneling_port); 1158 udp->uh_dport = tp->t_port; 1159 ulen = hdrlen + len - sizeof(struct ip6_hdr); 1160 udp->uh_ulen = htons(ulen); 1161 th = (struct tcphdr *)(udp + 1); 1162 } else { 1163 th = (struct tcphdr *)(ip6 + 1); 1164 } 1165 tcpip_fillheaders(inp, tp->t_port, ip6, th); 1166 } else 1167#endif /* INET6 */ 1168 { 1169 ip = mtod(m, struct ip *); 1170 if (tp->t_port) { 1171 udp = (struct udphdr *)((caddr_t)ip + sizeof(struct ip)); 1172 udp->uh_sport = htons(V_tcp_udp_tunneling_port); 1173 udp->uh_dport = tp->t_port; 1174 ulen = hdrlen + len - sizeof(struct ip); 1175 udp->uh_ulen = htons(ulen); 1176 th = (struct tcphdr *)(udp + 1); 1177 } else 1178 th = (struct tcphdr *)(ip + 1); 1179 tcpip_fillheaders(inp, tp->t_port, ip, th); 1180 } 1181 1182 /* 1183 * Fill in fields, remembering maximum advertised 1184 * window for use in delaying messages about window sizes. 1185 * If resending a FIN, be sure not to use a new sequence number. 1186 */ 1187 if (flags & TH_FIN && tp->t_flags & TF_SENTFIN && 1188 tp->snd_nxt == tp->snd_max) 1189 tp->snd_nxt--; 1190 /* 1191 * If we are starting a connection, send ECN setup 1192 * SYN packet. If we are on a retransmit, we may 1193 * resend those bits a number of times as per 1194 * RFC 3168. 1195 */ 1196 if (tp->t_state == TCPS_SYN_SENT && V_tcp_do_ecn) { 1197 flags |= tcp_ecn_output_syn_sent(tp); 1198 } 1199 /* Also handle parallel SYN for ECN */ 1200 if ((TCPS_HAVERCVDSYN(tp->t_state)) && 1201 (tp->t_flags2 & (TF2_ECN_PERMIT | TF2_ACE_PERMIT))) { 1202 int ect = tcp_ecn_output_established(tp, &flags, len, sack_rxmit); 1203 if ((tp->t_state == TCPS_SYN_RECEIVED) && 1204 (tp->t_flags2 & TF2_ECN_SND_ECE)) 1205 tp->t_flags2 &= ~TF2_ECN_SND_ECE; 1206#ifdef INET6 1207 if (isipv6) { 1208 ip6->ip6_flow &= ~htonl(IPTOS_ECN_MASK << IPV6_FLOWLABEL_LEN); 1209 ip6->ip6_flow |= htonl(ect << IPV6_FLOWLABEL_LEN); 1210 } 1211 else 1212#endif 1213 { 1214 ip->ip_tos &= ~IPTOS_ECN_MASK; 1215 ip->ip_tos |= ect; 1216 } 1217 } 1218 1219 /* 1220 * If we are doing retransmissions, then snd_nxt will 1221 * not reflect the first unsent octet. For ACK only 1222 * packets, we do not want the sequence number of the 1223 * retransmitted packet, we want the sequence number 1224 * of the next unsent octet. So, if there is no data 1225 * (and no SYN or FIN), use snd_max instead of snd_nxt 1226 * when filling in ti_seq. But if we are in persist 1227 * state, snd_max might reflect one byte beyond the 1228 * right edge of the window, so use snd_nxt in that 1229 * case, since we know we aren't doing a retransmission. 1230 * (retransmit and persist are mutually exclusive...) 1231 */ 1232 if (sack_rxmit == 0) { 1233 if (len || (flags & (TH_SYN|TH_FIN)) || 1234 tcp_timer_active(tp, TT_PERSIST)) 1235 th->th_seq = htonl(tp->snd_nxt); 1236 else 1237 th->th_seq = htonl(tp->snd_max); 1238 } else { 1239 th->th_seq = htonl(p->rxmit); 1240 p->rxmit += len; 1241 /* 1242 * Lost Retransmission Detection 1243 * trigger resending of a (then 1244 * still existing) hole, when 1245 * fack acks recoverypoint. 1246 */ 1247 if ((tp->t_flags & TF_LRD) && SEQ_GEQ(p->rxmit, p->end)) 1248 p->rxmit = tp->snd_recover; 1249 tp->sackhint.sack_bytes_rexmit += len; 1250 } 1251 if (IN_RECOVERY(tp->t_flags)) { 1252 /* 1253 * Account all bytes transmitted while 1254 * IN_RECOVERY, simplifying PRR and 1255 * Lost Retransmit Detection 1256 */ 1257 tp->sackhint.prr_out += len; 1258 } 1259 th->th_ack = htonl(tp->rcv_nxt); 1260 if (optlen) { 1261 bcopy(opt, th + 1, optlen); 1262 th->th_off = (sizeof (struct tcphdr) + optlen) >> 2; 1263 } 1264 tcp_set_flags(th, flags); 1265 /* 1266 * Calculate receive window. Don't shrink window, 1267 * but avoid silly window syndrome. 1268 * If a RST segment is sent, advertise a window of zero. 1269 */ 1270 if (flags & TH_RST) { 1271 recwin = 0; 1272 } else { 1273 if (recwin < (so->so_rcv.sb_hiwat / 4) && 1274 recwin < tp->t_maxseg) 1275 recwin = 0; 1276 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt) && 1277 recwin < (tp->rcv_adv - tp->rcv_nxt)) 1278 recwin = (tp->rcv_adv - tp->rcv_nxt); 1279 } 1280 /* 1281 * According to RFC1323 the window field in a SYN (i.e., a <SYN> 1282 * or <SYN,ACK>) segment itself is never scaled. The <SYN,ACK> 1283 * case is handled in syncache. 1284 */ 1285 if (flags & TH_SYN) 1286 th->th_win = htons((u_short) 1287 (min(sbspace(&so->so_rcv), TCP_MAXWIN))); 1288 else { 1289 /* Avoid shrinking window with window scaling. */ 1290 recwin = roundup2(recwin, 1 << tp->rcv_scale); 1291 th->th_win = htons((u_short)(recwin >> tp->rcv_scale)); 1292 } 1293 1294 /* 1295 * Adjust the RXWIN0SENT flag - indicate that we have advertised 1296 * a 0 window. This may cause the remote transmitter to stall. This 1297 * flag tells soreceive() to disable delayed acknowledgements when 1298 * draining the buffer. This can occur if the receiver is attempting 1299 * to read more data than can be buffered prior to transmitting on 1300 * the connection. 1301 */ 1302 if (th->th_win == 0) { 1303 tp->t_sndzerowin++; 1304 tp->t_flags |= TF_RXWIN0SENT; 1305 } else 1306 tp->t_flags &= ~TF_RXWIN0SENT; 1307 if (SEQ_GT(tp->snd_up, tp->snd_nxt)) { 1308 th->th_urp = htons((u_short)(tp->snd_up - tp->snd_nxt)); 1309 th->th_flags |= TH_URG; 1310 } else 1311 /* 1312 * If no urgent pointer to send, then we pull 1313 * the urgent pointer to the left edge of the send window 1314 * so that it doesn't drift into the send window on sequence 1315 * number wraparound. 1316 */ 1317 tp->snd_up = tp->snd_una; /* drag it along */ 1318 1319 /* 1320 * Put TCP length in extended header, and then 1321 * checksum extended header and data. 1322 */ 1323 m->m_pkthdr.len = hdrlen + len; /* in6_cksum() need this */ 1324 1325#if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 1326 if (to.to_flags & TOF_SIGNATURE) { 1327 /* 1328 * Calculate MD5 signature and put it into the place 1329 * determined before. 1330 * NOTE: since TCP options buffer doesn't point into 1331 * mbuf's data, calculate offset and use it. 1332 */ 1333 if (!TCPMD5_ENABLED() || (error = TCPMD5_OUTPUT(m, th, 1334 (u_char *)(th + 1) + (to.to_signature - opt))) != 0) { 1335 /* 1336 * Do not send segment if the calculation of MD5 1337 * digest has failed. 1338 */ 1339 m_freem(m); 1340 goto out; 1341 } 1342 } 1343#endif 1344#ifdef INET6 1345 if (isipv6) { 1346 /* 1347 * There is no need to fill in ip6_plen right now. 1348 * It will be filled later by ip6_output. 1349 */ 1350 if (tp->t_port) { 1351 m->m_pkthdr.csum_flags = CSUM_UDP_IPV6; 1352 m->m_pkthdr.csum_data = offsetof(struct udphdr, uh_sum); 1353 udp->uh_sum = in6_cksum_pseudo(ip6, ulen, IPPROTO_UDP, 0); 1354 th->th_sum = htons(0); 1355 UDPSTAT_INC(udps_opackets); 1356 } else { 1357 m->m_pkthdr.csum_flags = CSUM_TCP_IPV6; 1358 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 1359 th->th_sum = in6_cksum_pseudo(ip6, 1360 sizeof(struct tcphdr) + optlen + len, IPPROTO_TCP, 1361 0); 1362 } 1363 } 1364#endif 1365#if defined(INET6) && defined(INET) 1366 else 1367#endif 1368#ifdef INET 1369 { 1370 if (tp->t_port) { 1371 m->m_pkthdr.csum_flags = CSUM_UDP; 1372 m->m_pkthdr.csum_data = offsetof(struct udphdr, uh_sum); 1373 udp->uh_sum = in_pseudo(ip->ip_src.s_addr, 1374 ip->ip_dst.s_addr, htons(ulen + IPPROTO_UDP)); 1375 th->th_sum = htons(0); 1376 UDPSTAT_INC(udps_opackets); 1377 } else { 1378 m->m_pkthdr.csum_flags = CSUM_TCP; 1379 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 1380 th->th_sum = in_pseudo(ip->ip_src.s_addr, 1381 ip->ip_dst.s_addr, htons(sizeof(struct tcphdr) + 1382 IPPROTO_TCP + len + optlen)); 1383 } 1384 1385 /* IP version must be set here for ipv4/ipv6 checking later */ 1386 KASSERT(ip->ip_v == IPVERSION, 1387 ("%s: IP version incorrect: %d", __func__, ip->ip_v)); 1388 } 1389#endif 1390 1391 /* 1392 * Enable TSO and specify the size of the segments. 1393 * The TCP pseudo header checksum is always provided. 1394 */ 1395 if (tso) { 1396 KASSERT(len > tp->t_maxseg - optlen, 1397 ("%s: len <= tso_segsz", __func__)); 1398 m->m_pkthdr.csum_flags |= CSUM_TSO; 1399 m->m_pkthdr.tso_segsz = tp->t_maxseg - optlen; 1400 } 1401 1402 KASSERT(len + hdrlen == m_length(m, NULL), 1403 ("%s: mbuf chain shorter than expected: %d + %u != %u", 1404 __func__, len, hdrlen, m_length(m, NULL))); 1405 1406#ifdef TCP_HHOOK 1407 /* Run HHOOK_TCP_ESTABLISHED_OUT helper hooks. */ 1408 hhook_run_tcp_est_out(tp, th, &to, len, tso); 1409#endif 1410 1411 TCP_PROBE3(debug__output, tp, th, m); 1412 1413 /* We're getting ready to send; log now. */ 1414 /* XXXMT: We are not honoring verbose logging. */ 1415 1416 if (tcp_bblogging_on(tp)) 1417 lgb = tcp_log_event(tp, th, &so->so_rcv, &so->so_snd, 1418 TCP_LOG_OUT, ERRNO_UNK, len, NULL, false, NULL, NULL, 0, 1419 NULL); 1420 else 1421 lgb = NULL; 1422 1423 /* 1424 * Fill in IP length and desired time to live and 1425 * send to IP level. There should be a better way 1426 * to handle ttl and tos; we could keep them in 1427 * the template, but need a way to checksum without them. 1428 */ 1429 /* 1430 * m->m_pkthdr.len should have been set before checksum calculation, 1431 * because in6_cksum() need it. 1432 */ 1433#ifdef INET6 1434 if (isipv6) { 1435 /* 1436 * we separately set hoplimit for every segment, since the 1437 * user might want to change the value via setsockopt. 1438 * Also, desired default hop limit might be changed via 1439 * Neighbor Discovery. 1440 */ 1441 ip6->ip6_hlim = in6_selecthlim(inp, NULL); 1442 1443 /* 1444 * Set the packet size here for the benefit of DTrace probes. 1445 * ip6_output() will set it properly; it's supposed to include 1446 * the option header lengths as well. 1447 */ 1448 ip6->ip6_plen = htons(m->m_pkthdr.len - sizeof(*ip6)); 1449 1450 if (V_path_mtu_discovery && tp->t_maxseg > V_tcp_minmss) 1451 tp->t_flags2 |= TF2_PLPMTU_PMTUD; 1452 else 1453 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD; 1454 1455 if (tp->t_state == TCPS_SYN_SENT) 1456 TCP_PROBE5(connect__request, NULL, tp, ip6, tp, th); 1457 1458 TCP_PROBE5(send, NULL, tp, ip6, tp, th); 1459 1460#ifdef TCPPCAP 1461 /* Save packet, if requested. */ 1462 tcp_pcap_add(th, m, &(tp->t_outpkts)); 1463#endif 1464 1465 /* TODO: IPv6 IP6TOS_ECT bit on */ 1466 error = ip6_output(m, inp->in6p_outputopts, &inp->inp_route6, 1467 ((so->so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0), 1468 NULL, NULL, inp); 1469 1470 if (error == EMSGSIZE && inp->inp_route6.ro_nh != NULL) 1471 mtu = inp->inp_route6.ro_nh->nh_mtu; 1472 } 1473#endif /* INET6 */ 1474#if defined(INET) && defined(INET6) 1475 else 1476#endif 1477#ifdef INET 1478 { 1479 ip->ip_len = htons(m->m_pkthdr.len); 1480#ifdef INET6 1481 if (inp->inp_vflag & INP_IPV6PROTO) 1482 ip->ip_ttl = in6_selecthlim(inp, NULL); 1483#endif /* INET6 */ 1484 /* 1485 * If we do path MTU discovery, then we set DF on every packet. 1486 * This might not be the best thing to do according to RFC3390 1487 * Section 2. However the tcp hostcache migitates the problem 1488 * so it affects only the first tcp connection with a host. 1489 * 1490 * NB: Don't set DF on small MTU/MSS to have a safe fallback. 1491 */ 1492 if (V_path_mtu_discovery && tp->t_maxseg > V_tcp_minmss) { 1493 tp->t_flags2 |= TF2_PLPMTU_PMTUD; 1494 if (tp->t_port == 0 || len < V_tcp_minmss) { 1495 ip->ip_off |= htons(IP_DF); 1496 } 1497 } else { 1498 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD; 1499 } 1500 1501 if (tp->t_state == TCPS_SYN_SENT) 1502 TCP_PROBE5(connect__request, NULL, tp, ip, tp, th); 1503 1504 TCP_PROBE5(send, NULL, tp, ip, tp, th); 1505 1506#ifdef TCPPCAP 1507 /* Save packet, if requested. */ 1508 tcp_pcap_add(th, m, &(tp->t_outpkts)); 1509#endif 1510 1511 error = ip_output(m, inp->inp_options, &inp->inp_route, 1512 ((so->so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0), 0, inp); 1513 1514 if (error == EMSGSIZE && inp->inp_route.ro_nh != NULL) 1515 mtu = inp->inp_route.ro_nh->nh_mtu; 1516 } 1517#endif /* INET */ 1518 1519 if (lgb != NULL) { 1520 lgb->tlb_errno = error; 1521 lgb = NULL; 1522 } 1523out: 1524 if (error == 0) 1525 tcp_account_for_send(tp, len, (tp->snd_nxt != tp->snd_max), 0, hw_tls); 1526 /* 1527 * In transmit state, time the transmission and arrange for 1528 * the retransmit. In persist state, just set snd_max. In a closed 1529 * state just return. 1530 */ 1531 if (flags & TH_RST) { 1532 TCPSTAT_INC(tcps_sndtotal); 1533 return (0); 1534 } else if ((tp->t_flags & TF_FORCEDATA) == 0 || 1535 !tcp_timer_active(tp, TT_PERSIST)) { 1536 tcp_seq startseq = tp->snd_nxt; 1537 1538 /* 1539 * Advance snd_nxt over sequence space of this segment. 1540 */ 1541 if (flags & (TH_SYN|TH_FIN)) { 1542 if (flags & TH_SYN) 1543 tp->snd_nxt++; 1544 if (flags & TH_FIN) { 1545 tp->snd_nxt++; 1546 tp->t_flags |= TF_SENTFIN; 1547 } 1548 } 1549 if (sack_rxmit) 1550 goto timer; 1551 tp->snd_nxt += len; 1552 if (SEQ_GT(tp->snd_nxt, tp->snd_max)) { 1553 /* 1554 * Update "made progress" indication if we just 1555 * added new data to an empty socket buffer. 1556 */ 1557 if (tp->snd_una == tp->snd_max) 1558 tp->t_acktime = ticks; 1559 tp->snd_max = tp->snd_nxt; 1560 /* 1561 * Time this transmission if not a retransmission and 1562 * not currently timing anything. 1563 */ 1564 tp->t_sndtime = ticks; 1565 if (tp->t_rtttime == 0) { 1566 tp->t_rtttime = ticks; 1567 tp->t_rtseq = startseq; 1568 TCPSTAT_INC(tcps_segstimed); 1569 } 1570#ifdef STATS 1571 if (!(tp->t_flags & TF_GPUTINPROG) && len) { 1572 tp->t_flags |= TF_GPUTINPROG; 1573 tp->gput_seq = startseq; 1574 tp->gput_ack = startseq + 1575 ulmin(sbavail(&so->so_snd) - off, sendwin); 1576 tp->gput_ts = tcp_ts_getticks(); 1577 } 1578#endif /* STATS */ 1579 } 1580 1581 /* 1582 * Set retransmit timer if not currently set, 1583 * and not doing a pure ack or a keep-alive probe. 1584 * Initial value for retransmit timer is smoothed 1585 * round-trip time + 2 * round-trip time variance. 1586 * Initialize shift counter which is used for backoff 1587 * of retransmit time. 1588 */ 1589timer: 1590 if (!tcp_timer_active(tp, TT_REXMT) && 1591 ((sack_rxmit && tp->snd_nxt != tp->snd_max) || 1592 (tp->snd_nxt != tp->snd_una))) { 1593 if (tcp_timer_active(tp, TT_PERSIST)) { 1594 tcp_timer_activate(tp, TT_PERSIST, 0); 1595 tp->t_rxtshift = 0; 1596 } 1597 tcp_timer_activate(tp, TT_REXMT, TP_RXTCUR(tp)); 1598 } else if (len == 0 && sbavail(&so->so_snd) && 1599 !tcp_timer_active(tp, TT_REXMT) && 1600 !tcp_timer_active(tp, TT_PERSIST)) { 1601 /* 1602 * Avoid a situation where we do not set persist timer 1603 * after a zero window condition. For example: 1604 * 1) A -> B: packet with enough data to fill the window 1605 * 2) B -> A: ACK for #1 + new data (0 window 1606 * advertisement) 1607 * 3) A -> B: ACK for #2, 0 len packet 1608 * 1609 * In this case, A will not activate the persist timer, 1610 * because it chose to send a packet. Unless tcp_output 1611 * is called for some other reason (delayed ack timer, 1612 * another input packet from B, socket syscall), A will 1613 * not send zero window probes. 1614 * 1615 * So, if you send a 0-length packet, but there is data 1616 * in the socket buffer, and neither the rexmt or 1617 * persist timer is already set, then activate the 1618 * persist timer. 1619 */ 1620 tp->t_rxtshift = 0; 1621 tcp_setpersist(tp); 1622 } 1623 } else { 1624 /* 1625 * Persist case, update snd_max but since we are in 1626 * persist mode (no window) we do not update snd_nxt. 1627 */ 1628 int xlen = len; 1629 if (flags & TH_SYN) 1630 ++xlen; 1631 if (flags & TH_FIN) { 1632 ++xlen; 1633 tp->t_flags |= TF_SENTFIN; 1634 } 1635 if (SEQ_GT(tp->snd_nxt + xlen, tp->snd_max)) 1636 tp->snd_max = tp->snd_nxt + xlen; 1637 } 1638 if ((error == 0) && 1639 (TCPS_HAVEESTABLISHED(tp->t_state) && 1640 (tp->t_flags & TF_SACK_PERMIT) && 1641 tp->rcv_numsacks > 0)) { 1642 /* Clean up any DSACK's sent */ 1643 tcp_clean_dsack_blocks(tp); 1644 } 1645 if (error) { 1646 /* 1647 * We know that the packet was lost, so back out the 1648 * sequence number advance, if any. 1649 * 1650 * If the error is EPERM the packet got blocked by the 1651 * local firewall. Normally we should terminate the 1652 * connection but the blocking may have been spurious 1653 * due to a firewall reconfiguration cycle. So we treat 1654 * it like a packet loss and let the retransmit timer and 1655 * timeouts do their work over time. 1656 * XXX: It is a POLA question whether calling tcp_drop right 1657 * away would be the really correct behavior instead. 1658 */ 1659 if (((tp->t_flags & TF_FORCEDATA) == 0 || 1660 !tcp_timer_active(tp, TT_PERSIST)) && 1661 ((flags & TH_SYN) == 0) && 1662 (error != EPERM)) { 1663 if (sack_rxmit) { 1664 p->rxmit = SEQ_MIN(p->end, p->rxmit) - len; 1665 tp->sackhint.sack_bytes_rexmit -= len; 1666 KASSERT(tp->sackhint.sack_bytes_rexmit >= 0, 1667 ("sackhint bytes rtx >= 0")); 1668 KASSERT((flags & TH_FIN) == 0, 1669 ("error while FIN with SACK rxmit")); 1670 } else { 1671 tp->snd_nxt -= len; 1672 if (flags & TH_FIN) 1673 tp->snd_nxt--; 1674 } 1675 if (IN_RECOVERY(tp->t_flags)) 1676 tp->sackhint.prr_out -= len; 1677 } 1678 SOCKBUF_UNLOCK_ASSERT(&so->so_snd); /* Check gotos. */ 1679 switch (error) { 1680 case EACCES: 1681 case EPERM: 1682 tp->t_softerror = error; 1683 return (error); 1684 case ENOBUFS: 1685 TCP_XMIT_TIMER_ASSERT(tp, len, flags); 1686 tp->snd_cwnd = tp->t_maxseg; 1687 return (0); 1688 case EMSGSIZE: 1689 /* 1690 * For some reason the interface we used initially 1691 * to send segments changed to another or lowered 1692 * its MTU. 1693 * If TSO was active we either got an interface 1694 * without TSO capabilits or TSO was turned off. 1695 * If we obtained mtu from ip_output() then update 1696 * it and try again. 1697 */ 1698 if (tso) 1699 tp->t_flags &= ~TF_TSO; 1700 if (mtu != 0) { 1701 tcp_mss_update(tp, -1, mtu, NULL, NULL); 1702 goto again; 1703 } 1704 return (error); 1705 case EHOSTDOWN: 1706 case EHOSTUNREACH: 1707 case ENETDOWN: 1708 case ENETUNREACH: 1709 if (TCPS_HAVERCVDSYN(tp->t_state)) { 1710 tp->t_softerror = error; 1711 return (0); 1712 } 1713 /* FALLTHROUGH */ 1714 default: 1715 return (error); 1716 } 1717 } 1718 TCPSTAT_INC(tcps_sndtotal); 1719 1720 /* 1721 * Data sent (as far as we can tell). 1722 * If this advertises a larger window than any other segment, 1723 * then remember the size of the advertised window. 1724 * Any pending ACK has now been sent. 1725 */ 1726 if (SEQ_GT(tp->rcv_nxt + recwin, tp->rcv_adv)) 1727 tp->rcv_adv = tp->rcv_nxt + recwin; 1728 tp->last_ack_sent = tp->rcv_nxt; 1729 tp->t_flags &= ~(TF_ACKNOW | TF_DELACK); 1730 if (tcp_timer_active(tp, TT_DELACK)) 1731 tcp_timer_activate(tp, TT_DELACK, 0); 1732 if (sendalot) 1733 goto again; 1734 return (0); 1735} 1736 1737void 1738tcp_setpersist(struct tcpcb *tp) 1739{ 1740 int t = ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1; 1741 int tt; 1742 int maxunacktime; 1743 1744 tp->t_flags &= ~TF_PREVVALID; 1745 if (tcp_timer_active(tp, TT_REXMT)) 1746 panic("tcp_setpersist: retransmit pending"); 1747 /* 1748 * If the state is already closed, don't bother. 1749 */ 1750 if (tp->t_state == TCPS_CLOSED) 1751 return; 1752 1753 /* 1754 * Start/restart persistence timer. 1755 */ 1756 TCPT_RANGESET(tt, t * tcp_backoff[tp->t_rxtshift], 1757 tcp_persmin, tcp_persmax); 1758 if (TP_MAXUNACKTIME(tp) && tp->t_acktime) { 1759 maxunacktime = tp->t_acktime + TP_MAXUNACKTIME(tp) - ticks; 1760 if (maxunacktime < 1) 1761 maxunacktime = 1; 1762 if (maxunacktime < tt) 1763 tt = maxunacktime; 1764 } 1765 tcp_timer_activate(tp, TT_PERSIST, tt); 1766 if (tp->t_rxtshift < V_tcp_retries) 1767 tp->t_rxtshift++; 1768} 1769 1770/* 1771 * Insert TCP options according to the supplied parameters to the place 1772 * optp in a consistent way. Can handle unaligned destinations. 1773 * 1774 * The order of the option processing is crucial for optimal packing and 1775 * alignment for the scarce option space. 1776 * 1777 * The optimal order for a SYN/SYN-ACK segment is: 1778 * MSS (4) + NOP (1) + Window scale (3) + SACK permitted (2) + 1779 * Timestamp (10) + Signature (18) = 38 bytes out of a maximum of 40. 1780 * 1781 * The SACK options should be last. SACK blocks consume 8*n+2 bytes. 1782 * So a full size SACK blocks option is 34 bytes (with 4 SACK blocks). 1783 * At minimum we need 10 bytes (to generate 1 SACK block). If both 1784 * TCP Timestamps (12 bytes) and TCP Signatures (18 bytes) are present, 1785 * we only have 10 bytes for SACK options (40 - (12 + 18)). 1786 */ 1787int 1788tcp_addoptions(struct tcpopt *to, u_char *optp) 1789{ 1790 u_int32_t mask, optlen = 0; 1791 1792 for (mask = 1; mask < TOF_MAXOPT; mask <<= 1) { 1793 if ((to->to_flags & mask) != mask) 1794 continue; 1795 if (optlen == TCP_MAXOLEN) 1796 break; 1797 switch (to->to_flags & mask) { 1798 case TOF_MSS: 1799 while (optlen % 4) { 1800 optlen += TCPOLEN_NOP; 1801 *optp++ = TCPOPT_NOP; 1802 } 1803 if (TCP_MAXOLEN - optlen < TCPOLEN_MAXSEG) 1804 continue; 1805 optlen += TCPOLEN_MAXSEG; 1806 *optp++ = TCPOPT_MAXSEG; 1807 *optp++ = TCPOLEN_MAXSEG; 1808 to->to_mss = htons(to->to_mss); 1809 bcopy((u_char *)&to->to_mss, optp, sizeof(to->to_mss)); 1810 optp += sizeof(to->to_mss); 1811 break; 1812 case TOF_SCALE: 1813 while (!optlen || optlen % 2 != 1) { 1814 optlen += TCPOLEN_NOP; 1815 *optp++ = TCPOPT_NOP; 1816 } 1817 if (TCP_MAXOLEN - optlen < TCPOLEN_WINDOW) 1818 continue; 1819 optlen += TCPOLEN_WINDOW; 1820 *optp++ = TCPOPT_WINDOW; 1821 *optp++ = TCPOLEN_WINDOW; 1822 *optp++ = to->to_wscale; 1823 break; 1824 case TOF_SACKPERM: 1825 while (optlen % 2) { 1826 optlen += TCPOLEN_NOP; 1827 *optp++ = TCPOPT_NOP; 1828 } 1829 if (TCP_MAXOLEN - optlen < TCPOLEN_SACK_PERMITTED) 1830 continue; 1831 optlen += TCPOLEN_SACK_PERMITTED; 1832 *optp++ = TCPOPT_SACK_PERMITTED; 1833 *optp++ = TCPOLEN_SACK_PERMITTED; 1834 break; 1835 case TOF_TS: 1836 while (!optlen || optlen % 4 != 2) { 1837 optlen += TCPOLEN_NOP; 1838 *optp++ = TCPOPT_NOP; 1839 } 1840 if (TCP_MAXOLEN - optlen < TCPOLEN_TIMESTAMP) 1841 continue; 1842 optlen += TCPOLEN_TIMESTAMP; 1843 *optp++ = TCPOPT_TIMESTAMP; 1844 *optp++ = TCPOLEN_TIMESTAMP; 1845 to->to_tsval = htonl(to->to_tsval); 1846 to->to_tsecr = htonl(to->to_tsecr); 1847 bcopy((u_char *)&to->to_tsval, optp, sizeof(to->to_tsval)); 1848 optp += sizeof(to->to_tsval); 1849 bcopy((u_char *)&to->to_tsecr, optp, sizeof(to->to_tsecr)); 1850 optp += sizeof(to->to_tsecr); 1851 break; 1852 case TOF_SIGNATURE: 1853 { 1854 int siglen = TCPOLEN_SIGNATURE - 2; 1855 1856 while (!optlen || optlen % 4 != 2) { 1857 optlen += TCPOLEN_NOP; 1858 *optp++ = TCPOPT_NOP; 1859 } 1860 if (TCP_MAXOLEN - optlen < TCPOLEN_SIGNATURE) { 1861 to->to_flags &= ~TOF_SIGNATURE; 1862 continue; 1863 } 1864 optlen += TCPOLEN_SIGNATURE; 1865 *optp++ = TCPOPT_SIGNATURE; 1866 *optp++ = TCPOLEN_SIGNATURE; 1867 to->to_signature = optp; 1868 while (siglen--) 1869 *optp++ = 0; 1870 break; 1871 } 1872 case TOF_SACK: 1873 { 1874 int sackblks = 0; 1875 struct sackblk *sack = (struct sackblk *)to->to_sacks; 1876 tcp_seq sack_seq; 1877 1878 while (!optlen || optlen % 4 != 2) { 1879 optlen += TCPOLEN_NOP; 1880 *optp++ = TCPOPT_NOP; 1881 } 1882 if (TCP_MAXOLEN - optlen < TCPOLEN_SACKHDR + TCPOLEN_SACK) 1883 continue; 1884 optlen += TCPOLEN_SACKHDR; 1885 *optp++ = TCPOPT_SACK; 1886 sackblks = min(to->to_nsacks, 1887 (TCP_MAXOLEN - optlen) / TCPOLEN_SACK); 1888 *optp++ = TCPOLEN_SACKHDR + sackblks * TCPOLEN_SACK; 1889 while (sackblks--) { 1890 sack_seq = htonl(sack->start); 1891 bcopy((u_char *)&sack_seq, optp, sizeof(sack_seq)); 1892 optp += sizeof(sack_seq); 1893 sack_seq = htonl(sack->end); 1894 bcopy((u_char *)&sack_seq, optp, sizeof(sack_seq)); 1895 optp += sizeof(sack_seq); 1896 optlen += TCPOLEN_SACK; 1897 sack++; 1898 } 1899 TCPSTAT_INC(tcps_sack_send_blocks); 1900 break; 1901 } 1902 case TOF_FASTOPEN: 1903 { 1904 int total_len; 1905 1906 /* XXX is there any point to aligning this option? */ 1907 total_len = TCPOLEN_FAST_OPEN_EMPTY + to->to_tfo_len; 1908 if (TCP_MAXOLEN - optlen < total_len) { 1909 to->to_flags &= ~TOF_FASTOPEN; 1910 continue; 1911 } 1912 *optp++ = TCPOPT_FAST_OPEN; 1913 *optp++ = total_len; 1914 if (to->to_tfo_len > 0) { 1915 bcopy(to->to_tfo_cookie, optp, to->to_tfo_len); 1916 optp += to->to_tfo_len; 1917 } 1918 optlen += total_len; 1919 break; 1920 } 1921 default: 1922 panic("%s: unknown TCP option type", __func__); 1923 break; 1924 } 1925 } 1926 1927 /* Terminate and pad TCP options to a 4 byte boundary. */ 1928 if (optlen % 4) { 1929 optlen += TCPOLEN_EOL; 1930 *optp++ = TCPOPT_EOL; 1931 } 1932 /* 1933 * According to RFC 793 (STD0007): 1934 * "The content of the header beyond the End-of-Option option 1935 * must be header padding (i.e., zero)." 1936 * and later: "The padding is composed of zeros." 1937 */ 1938 while (optlen % 4) { 1939 optlen += TCPOLEN_PAD; 1940 *optp++ = TCPOPT_PAD; 1941 } 1942 1943 KASSERT(optlen <= TCP_MAXOLEN, ("%s: TCP options too long", __func__)); 1944 return (optlen); 1945} 1946 1947/* 1948 * This is a copy of m_copym(), taking the TSO segment size/limit 1949 * constraints into account, and advancing the sndptr as it goes. 1950 */ 1951struct mbuf * 1952tcp_m_copym(struct mbuf *m, int32_t off0, int32_t *plen, 1953 int32_t seglimit, int32_t segsize, struct sockbuf *sb, bool hw_tls) 1954{ 1955#ifdef KERN_TLS 1956 struct ktls_session *tls, *ntls; 1957 struct mbuf *start __diagused; 1958#endif 1959 struct mbuf *n, **np; 1960 struct mbuf *top; 1961 int32_t off = off0; 1962 int32_t len = *plen; 1963 int32_t fragsize; 1964 int32_t len_cp = 0; 1965 int32_t *pkthdrlen; 1966 uint32_t mlen, frags; 1967 bool copyhdr; 1968 1969 KASSERT(off >= 0, ("tcp_m_copym, negative off %d", off)); 1970 KASSERT(len >= 0, ("tcp_m_copym, negative len %d", len)); 1971 if (off == 0 && m->m_flags & M_PKTHDR) 1972 copyhdr = true; 1973 else 1974 copyhdr = false; 1975 while (off > 0) { 1976 KASSERT(m != NULL, ("tcp_m_copym, offset > size of mbuf chain")); 1977 if (off < m->m_len) 1978 break; 1979 off -= m->m_len; 1980 if ((sb) && (m == sb->sb_sndptr)) { 1981 sb->sb_sndptroff += m->m_len; 1982 sb->sb_sndptr = m->m_next; 1983 } 1984 m = m->m_next; 1985 } 1986 np = ⊤ 1987 top = NULL; 1988 pkthdrlen = NULL; 1989#ifdef KERN_TLS 1990 if (hw_tls && (m->m_flags & M_EXTPG)) 1991 tls = m->m_epg_tls; 1992 else 1993 tls = NULL; 1994 start = m; 1995#endif 1996 while (len > 0) { 1997 if (m == NULL) { 1998 KASSERT(len == M_COPYALL, 1999 ("tcp_m_copym, length > size of mbuf chain")); 2000 *plen = len_cp; 2001 if (pkthdrlen != NULL) 2002 *pkthdrlen = len_cp; 2003 break; 2004 } 2005#ifdef KERN_TLS 2006 if (hw_tls) { 2007 if (m->m_flags & M_EXTPG) 2008 ntls = m->m_epg_tls; 2009 else 2010 ntls = NULL; 2011 2012 /* 2013 * Avoid mixing TLS records with handshake 2014 * data or TLS records from different 2015 * sessions. 2016 */ 2017 if (tls != ntls) { 2018 MPASS(m != start); 2019 *plen = len_cp; 2020 if (pkthdrlen != NULL) 2021 *pkthdrlen = len_cp; 2022 break; 2023 } 2024 } 2025#endif 2026 mlen = min(len, m->m_len - off); 2027 if (seglimit) { 2028 /* 2029 * For M_EXTPG mbufs, add 3 segments 2030 * + 1 in case we are crossing page boundaries 2031 * + 2 in case the TLS hdr/trailer are used 2032 * It is cheaper to just add the segments 2033 * than it is to take the cache miss to look 2034 * at the mbuf ext_pgs state in detail. 2035 */ 2036 if (m->m_flags & M_EXTPG) { 2037 fragsize = min(segsize, PAGE_SIZE); 2038 frags = 3; 2039 } else { 2040 fragsize = segsize; 2041 frags = 0; 2042 } 2043 2044 /* Break if we really can't fit anymore. */ 2045 if ((frags + 1) >= seglimit) { 2046 *plen = len_cp; 2047 if (pkthdrlen != NULL) 2048 *pkthdrlen = len_cp; 2049 break; 2050 } 2051 2052 /* 2053 * Reduce size if you can't copy the whole 2054 * mbuf. If we can't copy the whole mbuf, also 2055 * adjust len so the loop will end after this 2056 * mbuf. 2057 */ 2058 if ((frags + howmany(mlen, fragsize)) >= seglimit) { 2059 mlen = (seglimit - frags - 1) * fragsize; 2060 len = mlen; 2061 *plen = len_cp + len; 2062 if (pkthdrlen != NULL) 2063 *pkthdrlen = *plen; 2064 } 2065 frags += howmany(mlen, fragsize); 2066 if (frags == 0) 2067 frags++; 2068 seglimit -= frags; 2069 KASSERT(seglimit > 0, 2070 ("%s: seglimit went too low", __func__)); 2071 } 2072 if (copyhdr) 2073 n = m_gethdr(M_NOWAIT, m->m_type); 2074 else 2075 n = m_get(M_NOWAIT, m->m_type); 2076 *np = n; 2077 if (n == NULL) 2078 goto nospace; 2079 if (copyhdr) { 2080 if (!m_dup_pkthdr(n, m, M_NOWAIT)) 2081 goto nospace; 2082 if (len == M_COPYALL) 2083 n->m_pkthdr.len -= off0; 2084 else 2085 n->m_pkthdr.len = len; 2086 pkthdrlen = &n->m_pkthdr.len; 2087 copyhdr = false; 2088 } 2089 n->m_len = mlen; 2090 len_cp += n->m_len; 2091 if (m->m_flags & (M_EXT | M_EXTPG)) { 2092 n->m_data = m->m_data + off; 2093 mb_dupcl(n, m); 2094 } else 2095 bcopy(mtod(m, caddr_t)+off, mtod(n, caddr_t), 2096 (u_int)n->m_len); 2097 2098 if (sb && (sb->sb_sndptr == m) && 2099 ((n->m_len + off) >= m->m_len) && m->m_next) { 2100 sb->sb_sndptroff += m->m_len; 2101 sb->sb_sndptr = m->m_next; 2102 } 2103 off = 0; 2104 if (len != M_COPYALL) { 2105 len -= n->m_len; 2106 } 2107 m = m->m_next; 2108 np = &n->m_next; 2109 } 2110 return (top); 2111nospace: 2112 m_freem(top); 2113 return (NULL); 2114} 2115 2116void 2117tcp_sndbuf_autoscale(struct tcpcb *tp, struct socket *so, uint32_t sendwin) 2118{ 2119 2120 /* 2121 * Automatic sizing of send socket buffer. Often the send buffer 2122 * size is not optimally adjusted to the actual network conditions 2123 * at hand (delay bandwidth product). Setting the buffer size too 2124 * small limits throughput on links with high bandwidth and high 2125 * delay (eg. trans-continental/oceanic links). Setting the 2126 * buffer size too big consumes too much real kernel memory, 2127 * especially with many connections on busy servers. 2128 * 2129 * The criteria to step up the send buffer one notch are: 2130 * 1. receive window of remote host is larger than send buffer 2131 * (with a fudge factor of 5/4th); 2132 * 2. send buffer is filled to 7/8th with data (so we actually 2133 * have data to make use of it); 2134 * 3. send buffer fill has not hit maximal automatic size; 2135 * 4. our send window (slow start and cogestion controlled) is 2136 * larger than sent but unacknowledged data in send buffer. 2137 * 2138 * The remote host receive window scaling factor may limit the 2139 * growing of the send buffer before it reaches its allowed 2140 * maximum. 2141 * 2142 * It scales directly with slow start or congestion window 2143 * and does at most one step per received ACK. This fast 2144 * scaling has the drawback of growing the send buffer beyond 2145 * what is strictly necessary to make full use of a given 2146 * delay*bandwidth product. However testing has shown this not 2147 * to be much of an problem. At worst we are trading wasting 2148 * of available bandwidth (the non-use of it) for wasting some 2149 * socket buffer memory. 2150 * 2151 * TODO: Shrink send buffer during idle periods together 2152 * with congestion window. Requires another timer. Has to 2153 * wait for upcoming tcp timer rewrite. 2154 * 2155 * XXXGL: should there be used sbused() or sbavail()? 2156 */ 2157 if (V_tcp_do_autosndbuf && so->so_snd.sb_flags & SB_AUTOSIZE) { 2158 int lowat; 2159 2160 lowat = V_tcp_sendbuf_auto_lowat ? so->so_snd.sb_lowat : 0; 2161 if ((tp->snd_wnd / 4 * 5) >= so->so_snd.sb_hiwat - lowat && 2162 sbused(&so->so_snd) >= 2163 (so->so_snd.sb_hiwat / 8 * 7) - lowat && 2164 sbused(&so->so_snd) < V_tcp_autosndbuf_max && 2165 sendwin >= (sbused(&so->so_snd) - 2166 (tp->snd_nxt - tp->snd_una))) { 2167 if (!sbreserve_locked(so, SO_SND, 2168 min(so->so_snd.sb_hiwat + V_tcp_autosndbuf_inc, 2169 V_tcp_autosndbuf_max), curthread)) 2170 so->so_snd.sb_flags &= ~SB_AUTOSIZE; 2171 } 2172 } 2173} 2174