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 TCP_OFFLOAD 89 #include <netinet/tcp_offload.h> 90 #endif 91 #include <netinet/tcp_ecn.h> 92 93 #include <netipsec/ipsec_support.h> 94 95 #include <netinet/udp.h> 96 #include <netinet/udp_var.h> 97 #include <machine/in_cksum.h> 98 99 #include <security/mac/mac_framework.h> 100 101 VNET_DEFINE(int, path_mtu_discovery) = 1; 102 SYSCTL_INT(_net_inet_tcp, OID_AUTO, path_mtu_discovery, CTLFLAG_VNET | CTLFLAG_RW, 103 &VNET_NAME(path_mtu_discovery), 1, 104 "Enable Path MTU Discovery"); 105 106 VNET_DEFINE(int, tcp_do_tso) = 1; 107 SYSCTL_INT(_net_inet_tcp, OID_AUTO, tso, CTLFLAG_VNET | CTLFLAG_RW, 108 &VNET_NAME(tcp_do_tso), 0, 109 "Enable TCP Segmentation Offload"); 110 111 VNET_DEFINE(int, tcp_sendspace) = 1024*32; 112 #define V_tcp_sendspace VNET(tcp_sendspace) 113 SYSCTL_INT(_net_inet_tcp, TCPCTL_SENDSPACE, sendspace, CTLFLAG_VNET | CTLFLAG_RW, 114 &VNET_NAME(tcp_sendspace), 0, "Initial send socket buffer size"); 115 116 VNET_DEFINE(int, tcp_do_autosndbuf) = 1; 117 SYSCTL_INT(_net_inet_tcp, OID_AUTO, sendbuf_auto, CTLFLAG_VNET | CTLFLAG_RW, 118 &VNET_NAME(tcp_do_autosndbuf), 0, 119 "Enable automatic send buffer sizing"); 120 121 VNET_DEFINE(int, tcp_autosndbuf_inc) = 8*1024; 122 SYSCTL_INT(_net_inet_tcp, OID_AUTO, sendbuf_inc, CTLFLAG_VNET | CTLFLAG_RW, 123 &VNET_NAME(tcp_autosndbuf_inc), 0, 124 "Incrementor step size of automatic send buffer"); 125 126 VNET_DEFINE(int, tcp_autosndbuf_max) = 2*1024*1024; 127 SYSCTL_INT(_net_inet_tcp, OID_AUTO, sendbuf_max, CTLFLAG_VNET | CTLFLAG_RW, 128 &VNET_NAME(tcp_autosndbuf_max), 0, 129 "Max size of automatic send buffer"); 130 131 VNET_DEFINE(int, tcp_sendbuf_auto_lowat) = 0; 132 #define V_tcp_sendbuf_auto_lowat VNET(tcp_sendbuf_auto_lowat) 133 SYSCTL_INT(_net_inet_tcp, OID_AUTO, sendbuf_auto_lowat, CTLFLAG_VNET | CTLFLAG_RW, 134 &VNET_NAME(tcp_sendbuf_auto_lowat), 0, 135 "Modify threshold for auto send buffer growth to account for SO_SNDLOWAT"); 136 137 /* 138 * Make sure that either retransmit or persist timer is set for SYN, FIN and 139 * non-ACK. 140 */ 141 #define TCP_XMIT_TIMER_ASSERT(tp, len, th_flags) \ 142 KASSERT(((len) == 0 && ((th_flags) & (TH_SYN | TH_FIN)) == 0) ||\ 143 tcp_timer_active((tp), TT_REXMT) || \ 144 tcp_timer_active((tp), TT_PERSIST), \ 145 ("neither rexmt nor persist timer is set")) 146 147 #ifdef TCP_HHOOK 148 /* 149 * Wrapper for the TCP established output helper hook. 150 */ 151 void 152 hhook_run_tcp_est_out(struct tcpcb *tp, struct tcphdr *th, 153 struct tcpopt *to, uint32_t len, int tso) 154 { 155 struct tcp_hhook_data hhook_data; 156 157 if (V_tcp_hhh[HHOOK_TCP_EST_OUT]->hhh_nhooks > 0) { 158 hhook_data.tp = tp; 159 hhook_data.th = th; 160 hhook_data.to = to; 161 hhook_data.len = len; 162 hhook_data.tso = tso; 163 164 hhook_run_hooks(V_tcp_hhh[HHOOK_TCP_EST_OUT], &hhook_data, 165 &tp->t_osd); 166 } 167 } 168 #endif 169 170 /* 171 * CC wrapper hook functions 172 */ 173 void 174 cc_after_idle(struct tcpcb *tp) 175 { 176 INP_WLOCK_ASSERT(tptoinpcb(tp)); 177 178 if (CC_ALGO(tp)->after_idle != NULL) 179 CC_ALGO(tp)->after_idle(&tp->t_ccv); 180 } 181 182 /* 183 * Tcp output routine: figure out what should be sent and send it. 184 */ 185 int 186 tcp_default_output(struct tcpcb *tp) 187 { 188 struct socket *so = tptosocket(tp); 189 struct inpcb *inp = tptoinpcb(tp); 190 int32_t len; 191 uint32_t recwin, sendwin; 192 uint16_t flags; 193 int off, error = 0; /* Keep compiler happy */ 194 u_int if_hw_tsomaxsegcount = 0; 195 u_int if_hw_tsomaxsegsize = 0; 196 struct mbuf *m; 197 struct ip *ip = NULL; 198 struct tcphdr *th; 199 u_char opt[TCP_MAXOLEN]; 200 unsigned ipoptlen, optlen, hdrlen, ulen; 201 unsigned ipsec_optlen = 0; 202 int idle, sendalot, curticks; 203 int sack_bytes_rxmt; 204 struct sackhole *p; 205 int tso, mtu; 206 struct tcpopt to; 207 struct udphdr *udp = NULL; 208 struct tcp_log_buffer *lgb; 209 unsigned int wanted_cookie = 0; 210 unsigned int dont_sendalot = 0; 211 bool sack_rxmit; 212 #ifdef INET6 213 struct ip6_hdr *ip6 = NULL; 214 const bool isipv6 = (inp->inp_vflag & INP_IPV6) != 0; 215 #endif 216 #ifdef KERN_TLS 217 const bool hw_tls = tp->t_nic_ktls_xmit != 0; 218 #else 219 const bool hw_tls = false; 220 #endif 221 222 NET_EPOCH_ASSERT(); 223 INP_WLOCK_ASSERT(inp); 224 225 #ifdef TCP_OFFLOAD 226 if (tp->t_flags & TF_TOE) 227 return (tcp_offload_output(tp)); 228 #endif 229 230 /* 231 * For TFO connections in SYN_SENT or SYN_RECEIVED, 232 * only allow the initial SYN or SYN|ACK and those sent 233 * by the retransmit timer. 234 */ 235 if ((tp->t_flags & TF_FASTOPEN) && 236 ((tp->t_state == TCPS_SYN_SENT) || 237 (tp->t_state == TCPS_SYN_RECEIVED)) && 238 SEQ_GT(tp->snd_max, tp->snd_una) && /* SYN or SYN|ACK sent */ 239 (tp->snd_nxt != tp->snd_una)) /* not a retransmit */ 240 return (0); 241 242 /* 243 * Determine length of data that should be transmitted, 244 * and flags that will be used. 245 * If there is some data or critical controls (SYN, RST) 246 * to send, then transmit; otherwise, investigate further. 247 */ 248 idle = (tp->t_flags & TF_LASTIDLE) || (tp->snd_max == tp->snd_una); 249 if (idle && (((ticks - tp->t_rcvtime) >= tp->t_rxtcur) || 250 (tp->t_sndtime && ((ticks - tp->t_sndtime) >= tp->t_rxtcur)))) 251 cc_after_idle(tp); 252 tp->t_flags &= ~TF_LASTIDLE; 253 if (idle) { 254 if (tp->t_flags & TF_MORETOCOME) { 255 tp->t_flags |= TF_LASTIDLE; 256 idle = 0; 257 } 258 } 259 again: 260 sendwin = 0; 261 /* 262 * If we've recently taken a timeout, snd_max will be greater than 263 * snd_nxt. There may be SACK information that allows us to avoid 264 * resending already delivered data. Adjust snd_nxt accordingly. 265 */ 266 if ((tp->t_flags & TF_SACK_PERMIT) && 267 (tp->sackhint.nexthole != NULL) && 268 !IN_FASTRECOVERY(tp->t_flags)) { 269 sendwin = tcp_sack_adjust(tp); 270 } 271 sendalot = 0; 272 tso = 0; 273 mtu = 0; 274 off = tp->snd_nxt - tp->snd_una; 275 sendwin = min(tp->snd_wnd, tp->snd_cwnd + sendwin); 276 277 flags = tcp_outflags[tp->t_state]; 278 /* 279 * Send any SACK-generated retransmissions. If we're explicitly trying 280 * to send out new data (when sendalot is 1), bypass this function. 281 * If we retransmit in fast recovery mode, decrement snd_cwnd, since 282 * we're replacing a (future) new transmission with a retransmission 283 * now, and we previously incremented snd_cwnd in tcp_input(). 284 */ 285 /* 286 * Still in sack recovery , reset rxmit flag to zero. 287 */ 288 sack_bytes_rxmt = 0; 289 len = 0; 290 if ((tp->t_flags & TF_SACK_PERMIT) && 291 (IN_FASTRECOVERY(tp->t_flags) || 292 (SEQ_LT(tp->snd_nxt, tp->snd_max) && (tp->t_dupacks >= tcprexmtthresh))) && 293 (p = tcp_sack_output(tp, &sack_bytes_rxmt))) { 294 int32_t cwin; 295 296 if (IN_FASTRECOVERY(tp->t_flags)) { 297 cwin = imax(sendwin - tcp_compute_pipe(tp), 0); 298 } else { 299 cwin = imax(sendwin - off, 0); 300 } 301 /* Do not retransmit SACK segments beyond snd_recover */ 302 if (SEQ_GT(p->end, tp->snd_recover)) { 303 /* 304 * (At least) part of sack hole extends beyond 305 * snd_recover. Check to see if we can rexmit data 306 * for this hole. 307 */ 308 if (SEQ_GEQ(p->rxmit, tp->snd_recover)) { 309 /* 310 * Can't rexmit any more data for this hole. 311 * That data will be rexmitted in the next 312 * sack recovery episode, when snd_recover 313 * moves past p->rxmit. 314 */ 315 p = NULL; 316 sack_rxmit = false; 317 goto after_sack_rexmit; 318 } else { 319 /* Can rexmit part of the current hole */ 320 len = SEQ_SUB(tp->snd_recover, p->rxmit); 321 if (cwin <= len) { 322 len = cwin; 323 } else { 324 sendalot = 1; 325 } 326 } 327 } else { 328 len = SEQ_SUB(p->end, p->rxmit); 329 if (cwin <= len) { 330 len = cwin; 331 } else { 332 sendalot = 1; 333 } 334 } 335 /* we could have transmitted from the scoreboard, 336 * but sendwin (expected flightsize) - pipe didn't 337 * allow any transmission. 338 * Bypass recalculating the possible transmission 339 * length further down by setting sack_rxmit. 340 * Wouldn't be here if there would have been 341 * nothing in the scoreboard to transmit. 342 */ 343 if (len > 0) { 344 off = SEQ_SUB(p->rxmit, tp->snd_una); 345 KASSERT(off >= 0,("%s: sack block to the left of una : %d", 346 __func__, off)); 347 } 348 sack_rxmit = true; 349 } else { 350 p = NULL; 351 sack_rxmit = false; 352 } 353 after_sack_rexmit: 354 /* 355 * Get standard flags, and add SYN or FIN if requested by 'hidden' 356 * state flags. 357 */ 358 if (tp->t_flags & TF_NEEDFIN) 359 flags |= TH_FIN; 360 if (tp->t_flags & TF_NEEDSYN) 361 flags |= TH_SYN; 362 363 SOCK_SENDBUF_LOCK(so); 364 /* 365 * If in persist timeout with window of 0, send 1 byte. 366 * Otherwise, if window is small but nonzero 367 * and timer expired, we will send what we can 368 * and go to transmit state. 369 */ 370 if (tp->t_flags & TF_FORCEDATA) { 371 if (sendwin == 0) { 372 /* 373 * If we still have some data to send, then 374 * clear the FIN bit. Usually this would 375 * happen below when it realizes that we 376 * aren't sending all the data. However, 377 * if we have exactly 1 byte of unsent data, 378 * then it won't clear the FIN bit below, 379 * and if we are in persist state, we wind 380 * up sending the packet without recording 381 * that we sent the FIN bit. 382 * 383 * We can't just blindly clear the FIN bit, 384 * because if we don't have any more data 385 * to send then the probe will be the FIN 386 * itself. 387 */ 388 if (off < sbused(&so->so_snd)) 389 flags &= ~TH_FIN; 390 sendwin = 1; 391 } else { 392 tcp_timer_activate(tp, TT_PERSIST, 0); 393 tp->t_rxtshift = 0; 394 } 395 } 396 397 /* 398 * If snd_nxt == snd_max and we have transmitted a FIN, the 399 * offset will be > 0 even if so_snd.sb_cc is 0, resulting in 400 * a negative length. This can also occur when TCP opens up 401 * its congestion window while receiving additional duplicate 402 * acks after fast-retransmit because TCP will reset snd_nxt 403 * to snd_max after the fast-retransmit. 404 * 405 * In the normal retransmit-FIN-only case, however, snd_nxt will 406 * be set to snd_una, the offset will be 0, and the length may 407 * wind up 0. 408 * 409 * If sack_rxmit is true we are retransmitting from the scoreboard 410 * in which case len is already set. 411 */ 412 if (!sack_rxmit) { 413 if ((sack_bytes_rxmt == 0) || SEQ_LT(tp->snd_nxt, tp->snd_max)) { 414 len = imin(sbavail(&so->so_snd), sendwin) - off; 415 } else { 416 /* 417 * We are inside of a SACK recovery episode and are 418 * sending new data, having retransmitted all the 419 * data possible in the scoreboard. 420 */ 421 len = imax( 422 imin(sbavail(&so->so_snd), sendwin) - 423 imax(tcp_compute_pipe(tp), off), 0); 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, IP options (IPsec), and possibly SACK 519 * retransmits 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 ipoptlen += ipsec_optlen; 557 558 if ((tp->t_flags & TF_TSO) && V_tcp_do_tso && len > tp->t_maxseg && 559 (tp->t_port == 0) && 560 ((tp->t_flags & TF_SIGNATURE) == 0) && 561 (!sack_rxmit || V_tcp_sack_tso) && 562 (ipoptlen == 0 || (ipoptlen == ipsec_optlen && 563 (tp->t_flags2 & TF2_IPSEC_TSO) != 0)) && 564 !(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 } 693 dontupdate: 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 */ 756 just_return: 757 SOCK_SENDBUF_UNLOCK(so); 758 return (0); 759 760 send: 761 SOCK_SENDBUF_LOCK_ASSERT(so); 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 SOCK_SENDBUF_UNLOCK(so); 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 == ipsec_optlen, 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 ipsec_optlen - 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 - ipsec_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 SOCK_SENDBUF_UNLOCK(so); 984 error = EMSGSIZE; 985 sack_rxmit = false; 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 SOCK_SENDBUF_UNLOCK(so); 1066 error = ENOBUFS; 1067 sack_rxmit = false; 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 int32_t old_len; 1087 1088 if (SEQ_LT(tp->snd_nxt, tp->snd_max)) 1089 msb = NULL; 1090 else 1091 msb = &so->so_snd; 1092 old_len = len; 1093 m->m_next = tcp_m_copym(mb, moff, 1094 &len, if_hw_tsomaxsegcount, 1095 if_hw_tsomaxsegsize, msb, hw_tls); 1096 if (old_len != len) 1097 flags &= ~TH_FIN; 1098 if (len <= (tp->t_maxseg - optlen)) { 1099 /* 1100 * Must have ran out of mbufs for the copy 1101 * shorten it to no longer need tso. Lets 1102 * not put on sendalot since we are low on 1103 * mbufs. 1104 */ 1105 tso = 0; 1106 } 1107 if (m->m_next == NULL) { 1108 SOCK_SENDBUF_UNLOCK(so); 1109 (void) m_free(m); 1110 error = ENOBUFS; 1111 sack_rxmit = false; 1112 goto out; 1113 } 1114 } 1115 1116 /* 1117 * If we're sending everything we've got, set PUSH. 1118 * (This will keep happy those implementations which only 1119 * give data to the user when a buffer fills or 1120 * a PUSH comes in.) 1121 */ 1122 if (((uint32_t)off + (uint32_t)len == sbused(&so->so_snd)) && 1123 !(flags & TH_SYN)) 1124 flags |= TH_PUSH; 1125 SOCK_SENDBUF_UNLOCK(so); 1126 } else { 1127 SOCK_SENDBUF_UNLOCK(so); 1128 if (tp->t_flags & TF_ACKNOW) 1129 TCPSTAT_INC(tcps_sndacks); 1130 else if (flags & (TH_SYN|TH_FIN|TH_RST)) 1131 TCPSTAT_INC(tcps_sndctrl); 1132 else if (SEQ_GT(tp->snd_up, tp->snd_una)) 1133 TCPSTAT_INC(tcps_sndurg); 1134 else 1135 TCPSTAT_INC(tcps_sndwinup); 1136 1137 m = m_gethdr(M_NOWAIT, MT_DATA); 1138 if (m == NULL) { 1139 error = ENOBUFS; 1140 sack_rxmit = false; 1141 goto out; 1142 } 1143 #ifdef INET6 1144 if (isipv6 && (MHLEN < hdrlen + max_linkhdr) && 1145 MHLEN >= hdrlen) { 1146 M_ALIGN(m, hdrlen); 1147 } else 1148 #endif 1149 m->m_data += max_linkhdr; 1150 m->m_len = hdrlen; 1151 } 1152 SOCK_SENDBUF_UNLOCK_ASSERT(so); 1153 m->m_pkthdr.rcvif = (struct ifnet *)0; 1154 #ifdef MAC 1155 mac_inpcb_create_mbuf(inp, m); 1156 #endif 1157 #ifdef INET6 1158 if (isipv6) { 1159 ip6 = mtod(m, struct ip6_hdr *); 1160 if (tp->t_port) { 1161 udp = (struct udphdr *)((caddr_t)ip6 + sizeof(struct ip6_hdr)); 1162 udp->uh_sport = htons(V_tcp_udp_tunneling_port); 1163 udp->uh_dport = tp->t_port; 1164 ulen = hdrlen + len - sizeof(struct ip6_hdr); 1165 udp->uh_ulen = htons(ulen); 1166 th = (struct tcphdr *)(udp + 1); 1167 } else { 1168 th = (struct tcphdr *)(ip6 + 1); 1169 } 1170 tcpip_fillheaders(inp, tp->t_port, ip6, th); 1171 } else 1172 #endif /* INET6 */ 1173 { 1174 ip = mtod(m, struct ip *); 1175 if (tp->t_port) { 1176 udp = (struct udphdr *)((caddr_t)ip + sizeof(struct ip)); 1177 udp->uh_sport = htons(V_tcp_udp_tunneling_port); 1178 udp->uh_dport = tp->t_port; 1179 ulen = hdrlen + len - sizeof(struct ip); 1180 udp->uh_ulen = htons(ulen); 1181 th = (struct tcphdr *)(udp + 1); 1182 } else 1183 th = (struct tcphdr *)(ip + 1); 1184 tcpip_fillheaders(inp, tp->t_port, ip, th); 1185 } 1186 1187 /* 1188 * Fill in fields, remembering maximum advertised 1189 * window for use in delaying messages about window sizes. 1190 * If resending a FIN, be sure not to use a new sequence number. 1191 */ 1192 if (flags & TH_FIN && tp->t_flags & TF_SENTFIN && 1193 tp->snd_nxt == tp->snd_max) 1194 tp->snd_nxt--; 1195 /* 1196 * If we are starting a connection, send ECN setup 1197 * SYN packet. If we are on a retransmit, we may 1198 * resend those bits a number of times as per 1199 * RFC 3168. 1200 */ 1201 if (tp->t_state == TCPS_SYN_SENT && V_tcp_do_ecn) { 1202 flags |= tcp_ecn_output_syn_sent(tp); 1203 } 1204 /* Also handle parallel SYN for ECN */ 1205 if ((TCPS_HAVERCVDSYN(tp->t_state)) && 1206 (tp->t_flags2 & (TF2_ECN_PERMIT | TF2_ACE_PERMIT))) { 1207 int ect = tcp_ecn_output_established(tp, &flags, len, sack_rxmit); 1208 if ((tp->t_state == TCPS_SYN_RECEIVED) && 1209 (tp->t_flags2 & TF2_ECN_SND_ECE)) 1210 tp->t_flags2 &= ~TF2_ECN_SND_ECE; 1211 #ifdef INET6 1212 if (isipv6) { 1213 ip6->ip6_flow &= ~htonl(IPTOS_ECN_MASK << IPV6_FLOWLABEL_LEN); 1214 ip6->ip6_flow |= htonl(ect << IPV6_FLOWLABEL_LEN); 1215 } 1216 else 1217 #endif 1218 { 1219 ip->ip_tos &= ~IPTOS_ECN_MASK; 1220 ip->ip_tos |= ect; 1221 } 1222 } 1223 1224 /* 1225 * If we are doing retransmissions, then snd_nxt will 1226 * not reflect the first unsent octet. For ACK only 1227 * packets, we do not want the sequence number of the 1228 * retransmitted packet, we want the sequence number 1229 * of the next unsent octet. So, if there is no data 1230 * (and no SYN or FIN), use snd_max instead of snd_nxt 1231 * when filling in ti_seq. But if we are in persist 1232 * state, snd_max might reflect one byte beyond the 1233 * right edge of the window, so use snd_nxt in that 1234 * case, since we know we aren't doing a retransmission. 1235 * (retransmit and persist are mutually exclusive...) 1236 */ 1237 if (!sack_rxmit) { 1238 if (len || (flags & (TH_SYN|TH_FIN)) || 1239 tcp_timer_active(tp, TT_PERSIST)) 1240 th->th_seq = htonl(tp->snd_nxt); 1241 else 1242 th->th_seq = htonl(tp->snd_max); 1243 } else { 1244 th->th_seq = htonl(p->rxmit); 1245 p->rxmit += len; 1246 /* 1247 * Lost Retransmission Detection 1248 * trigger resending of a (then 1249 * still existing) hole, when 1250 * fack acks recoverypoint. 1251 */ 1252 if ((tp->t_flags & TF_LRD) && SEQ_GEQ(p->rxmit, p->end)) 1253 p->rxmit = SEQ_MAX(p->rxmit, tp->snd_recover); 1254 tp->sackhint.sack_bytes_rexmit += len; 1255 } 1256 if (IN_RECOVERY(tp->t_flags)) { 1257 /* 1258 * Account all bytes transmitted while 1259 * IN_RECOVERY, simplifying PRR and 1260 * Lost Retransmit Detection 1261 */ 1262 tp->sackhint.prr_out += len; 1263 } 1264 th->th_ack = htonl(tp->rcv_nxt); 1265 if (optlen) { 1266 bcopy(opt, th + 1, optlen); 1267 th->th_off = (sizeof (struct tcphdr) + optlen) >> 2; 1268 } 1269 /* 1270 * Calculate receive window. Don't shrink window, 1271 * but avoid silly window syndrome. 1272 * If a RST segment is sent, advertise a window of zero. 1273 */ 1274 if (flags & TH_RST) { 1275 recwin = 0; 1276 } else { 1277 if (recwin < (so->so_rcv.sb_hiwat / 4) && 1278 recwin < tp->t_maxseg) 1279 recwin = 0; 1280 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt) && 1281 recwin < (tp->rcv_adv - tp->rcv_nxt)) 1282 recwin = (tp->rcv_adv - tp->rcv_nxt); 1283 } 1284 /* 1285 * According to RFC1323 the window field in a SYN (i.e., a <SYN> 1286 * or <SYN,ACK>) segment itself is never scaled. The <SYN,ACK> 1287 * case is handled in syncache. 1288 */ 1289 if (flags & TH_SYN) 1290 th->th_win = htons((u_short) 1291 (min(sbspace(&so->so_rcv), TCP_MAXWIN))); 1292 else { 1293 /* Avoid shrinking window with window scaling. */ 1294 recwin = roundup2(recwin, 1 << tp->rcv_scale); 1295 th->th_win = htons((u_short)(recwin >> tp->rcv_scale)); 1296 } 1297 1298 /* 1299 * Adjust the RXWIN0SENT flag - indicate that we have advertised 1300 * a 0 window. This may cause the remote transmitter to stall. This 1301 * flag tells soreceive() to disable delayed acknowledgements when 1302 * draining the buffer. This can occur if the receiver is attempting 1303 * to read more data than can be buffered prior to transmitting on 1304 * the connection. 1305 */ 1306 if (th->th_win == 0) { 1307 tp->t_sndzerowin++; 1308 tp->t_flags |= TF_RXWIN0SENT; 1309 } else 1310 tp->t_flags &= ~TF_RXWIN0SENT; 1311 if (SEQ_GT(tp->snd_up, tp->snd_nxt)) { 1312 th->th_urp = htons((u_short)(tp->snd_up - tp->snd_nxt)); 1313 flags |= TH_URG; 1314 } else { 1315 /* 1316 * If no urgent pointer to send, then we pull 1317 * the urgent pointer to the left edge of the send window 1318 * so that it doesn't drift into the send window on sequence 1319 * number wraparound. 1320 */ 1321 tp->snd_up = tp->snd_una; /* drag it along */ 1322 } 1323 tcp_set_flags(th, flags); 1324 1325 /* 1326 * Put TCP length in extended header, and then 1327 * checksum extended header and data. 1328 */ 1329 m->m_pkthdr.len = hdrlen + len; /* in6_cksum() need this */ 1330 1331 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 1332 if (to.to_flags & TOF_SIGNATURE) { 1333 /* 1334 * Calculate MD5 signature and put it into the place 1335 * determined before. 1336 * NOTE: since TCP options buffer doesn't point into 1337 * mbuf's data, calculate offset and use it. 1338 */ 1339 if (!TCPMD5_ENABLED() || (error = TCPMD5_OUTPUT(m, th, 1340 (u_char *)(th + 1) + (to.to_signature - opt))) != 0) { 1341 /* 1342 * Do not send segment if the calculation of MD5 1343 * digest has failed. 1344 */ 1345 m_freem(m); 1346 goto out; 1347 } 1348 } 1349 #endif 1350 #ifdef INET6 1351 if (isipv6) { 1352 /* 1353 * There is no need to fill in ip6_plen right now. 1354 * It will be filled later by ip6_output. 1355 */ 1356 if (tp->t_port) { 1357 m->m_pkthdr.csum_flags = CSUM_UDP_IPV6; 1358 m->m_pkthdr.csum_data = offsetof(struct udphdr, uh_sum); 1359 udp->uh_sum = in6_cksum_pseudo(ip6, ulen, IPPROTO_UDP, 0); 1360 th->th_sum = htons(0); 1361 UDPSTAT_INC(udps_opackets); 1362 } else { 1363 m->m_pkthdr.csum_flags = CSUM_TCP_IPV6; 1364 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 1365 th->th_sum = in6_cksum_pseudo(ip6, 1366 sizeof(struct tcphdr) + optlen + len, IPPROTO_TCP, 1367 0); 1368 } 1369 } 1370 #endif 1371 #if defined(INET6) && defined(INET) 1372 else 1373 #endif 1374 #ifdef INET 1375 { 1376 if (tp->t_port) { 1377 m->m_pkthdr.csum_flags = CSUM_UDP; 1378 m->m_pkthdr.csum_data = offsetof(struct udphdr, uh_sum); 1379 udp->uh_sum = in_pseudo(ip->ip_src.s_addr, 1380 ip->ip_dst.s_addr, htons(ulen + IPPROTO_UDP)); 1381 th->th_sum = htons(0); 1382 UDPSTAT_INC(udps_opackets); 1383 } else { 1384 m->m_pkthdr.csum_flags = CSUM_TCP; 1385 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 1386 th->th_sum = in_pseudo(ip->ip_src.s_addr, 1387 ip->ip_dst.s_addr, htons(sizeof(struct tcphdr) + 1388 IPPROTO_TCP + len + optlen)); 1389 } 1390 1391 /* IP version must be set here for ipv4/ipv6 checking later */ 1392 KASSERT(ip->ip_v == IPVERSION, 1393 ("%s: IP version incorrect: %d", __func__, ip->ip_v)); 1394 } 1395 #endif 1396 1397 /* 1398 * Enable TSO and specify the size of the segments. 1399 * The TCP pseudo header checksum is always provided. 1400 */ 1401 if (tso) { 1402 KASSERT(len > tp->t_maxseg - optlen - ipsec_optlen, 1403 ("%s: len <= tso_segsz", __func__)); 1404 m->m_pkthdr.csum_flags |= CSUM_TSO; 1405 m->m_pkthdr.tso_segsz = tp->t_maxseg - optlen - ipsec_optlen; 1406 } 1407 1408 KASSERT(len + hdrlen == m_length(m, NULL), 1409 ("%s: mbuf chain shorter than expected: %d + %u != %u", 1410 __func__, len, hdrlen, m_length(m, NULL))); 1411 1412 #ifdef TCP_HHOOK 1413 /* Run HHOOK_TCP_ESTABLISHED_OUT helper hooks. */ 1414 hhook_run_tcp_est_out(tp, th, &to, len, tso); 1415 #endif 1416 1417 TCP_PROBE3(debug__output, tp, th, m); 1418 1419 /* We're getting ready to send; log now. */ 1420 /* XXXMT: We are not honoring verbose logging. */ 1421 1422 if (tcp_bblogging_on(tp)) 1423 lgb = tcp_log_event(tp, th, &so->so_rcv, &so->so_snd, 1424 TCP_LOG_OUT, ERRNO_UNK, len, NULL, false, NULL, NULL, 0, 1425 NULL); 1426 else 1427 lgb = NULL; 1428 1429 /* 1430 * Fill in IP length and desired time to live and 1431 * send to IP level. There should be a better way 1432 * to handle ttl and tos; we could keep them in 1433 * the template, but need a way to checksum without them. 1434 */ 1435 /* 1436 * m->m_pkthdr.len should have been set before checksum calculation, 1437 * because in6_cksum() need it. 1438 */ 1439 #ifdef INET6 1440 if (isipv6) { 1441 /* 1442 * we separately set hoplimit for every segment, since the 1443 * user might want to change the value via setsockopt. 1444 * Also, desired default hop limit might be changed via 1445 * Neighbor Discovery. 1446 */ 1447 ip6->ip6_hlim = in6_selecthlim(inp, NULL); 1448 1449 /* 1450 * Set the packet size here for the benefit of DTrace probes. 1451 * ip6_output() will set it properly; it's supposed to include 1452 * the option header lengths as well. 1453 */ 1454 ip6->ip6_plen = htons(m->m_pkthdr.len - sizeof(*ip6)); 1455 1456 if (V_path_mtu_discovery && tp->t_maxseg > V_tcp_minmss) 1457 tp->t_flags2 |= TF2_PLPMTU_PMTUD; 1458 else 1459 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD; 1460 1461 if (tp->t_state == TCPS_SYN_SENT) 1462 TCP_PROBE5(connect__request, NULL, tp, ip6, tp, th); 1463 1464 TCP_PROBE5(send, NULL, tp, ip6, tp, th); 1465 1466 1467 /* TODO: IPv6 IP6TOS_ECT bit on */ 1468 error = ip6_output(m, inp->in6p_outputopts, &inp->inp_route6, 1469 ((so->so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0), 1470 NULL, NULL, inp); 1471 1472 if (error == EMSGSIZE && inp->inp_route6.ro_nh != NULL) 1473 mtu = inp->inp_route6.ro_nh->nh_mtu; 1474 } 1475 #endif /* INET6 */ 1476 #if defined(INET) && defined(INET6) 1477 else 1478 #endif 1479 #ifdef INET 1480 { 1481 ip->ip_len = htons(m->m_pkthdr.len); 1482 #ifdef INET6 1483 if (inp->inp_vflag & INP_IPV6PROTO) 1484 ip->ip_ttl = in6_selecthlim(inp, NULL); 1485 #endif /* INET6 */ 1486 /* 1487 * If we do path MTU discovery, then we set DF on every packet. 1488 * This might not be the best thing to do according to RFC3390 1489 * Section 2. However the tcp hostcache migitates the problem 1490 * so it affects only the first tcp connection with a host. 1491 * 1492 * NB: Don't set DF on small MTU/MSS to have a safe fallback. 1493 */ 1494 if (V_path_mtu_discovery && tp->t_maxseg > V_tcp_minmss) { 1495 tp->t_flags2 |= TF2_PLPMTU_PMTUD; 1496 if (tp->t_port == 0 || len < V_tcp_minmss) { 1497 ip->ip_off |= htons(IP_DF); 1498 } 1499 } else { 1500 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD; 1501 } 1502 1503 if (tp->t_state == TCPS_SYN_SENT) 1504 TCP_PROBE5(connect__request, NULL, tp, ip, tp, th); 1505 1506 TCP_PROBE5(send, NULL, tp, ip, tp, th); 1507 1508 error = ip_output(m, inp->inp_options, &inp->inp_route, 1509 ((so->so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0), 0, inp); 1510 1511 if (error == EMSGSIZE && inp->inp_route.ro_nh != NULL) 1512 mtu = inp->inp_route.ro_nh->nh_mtu; 1513 } 1514 #endif /* INET */ 1515 1516 if (lgb != NULL) { 1517 lgb->tlb_errno = error; 1518 lgb = NULL; 1519 } 1520 out: 1521 if (error == 0) 1522 tcp_account_for_send(tp, len, (tp->snd_nxt != tp->snd_max), 0, hw_tls); 1523 /* 1524 * In transmit state, time the transmission and arrange for 1525 * the retransmit. In persist state, just set snd_max. In a closed 1526 * state just return. 1527 */ 1528 if (flags & TH_RST) { 1529 TCPSTAT_INC(tcps_sndtotal); 1530 return (0); 1531 } else if ((tp->t_flags & TF_FORCEDATA) == 0 || 1532 !tcp_timer_active(tp, TT_PERSIST)) { 1533 tcp_seq startseq = tp->snd_nxt; 1534 1535 /* 1536 * Advance snd_nxt over sequence space of this segment. 1537 */ 1538 if (flags & (TH_SYN|TH_FIN)) { 1539 if (flags & TH_SYN) 1540 tp->snd_nxt++; 1541 if (flags & TH_FIN) { 1542 tp->snd_nxt++; 1543 tp->t_flags |= TF_SENTFIN; 1544 } 1545 } 1546 if (sack_rxmit) 1547 goto timer; 1548 tp->snd_nxt += len; 1549 if (SEQ_GT(tp->snd_nxt, tp->snd_max)) { 1550 /* 1551 * Update "made progress" indication if we just 1552 * added new data to an empty socket buffer. 1553 */ 1554 if (tp->snd_una == tp->snd_max) 1555 tp->t_acktime = ticks; 1556 tp->snd_max = tp->snd_nxt; 1557 /* 1558 * Time this transmission if not a retransmission and 1559 * not currently timing anything. 1560 */ 1561 tp->t_sndtime = ticks; 1562 if (tp->t_rtttime == 0) { 1563 tp->t_rtttime = ticks; 1564 tp->t_rtseq = startseq; 1565 TCPSTAT_INC(tcps_segstimed); 1566 } 1567 #ifdef STATS 1568 if (!(tp->t_flags & TF_GPUTINPROG) && len) { 1569 tp->t_flags |= TF_GPUTINPROG; 1570 tp->gput_seq = startseq; 1571 tp->gput_ack = startseq + 1572 ulmin(sbavail(&so->so_snd) - off, sendwin); 1573 tp->gput_ts = tcp_ts_getticks(); 1574 } 1575 #endif /* STATS */ 1576 } 1577 1578 /* 1579 * Set retransmit timer if not currently set, 1580 * and not doing a pure ack or a keep-alive probe. 1581 * Initial value for retransmit timer is smoothed 1582 * round-trip time + 2 * round-trip time variance. 1583 * Initialize shift counter which is used for backoff 1584 * of retransmit time. 1585 */ 1586 timer: 1587 if (!tcp_timer_active(tp, TT_REXMT) && 1588 ((sack_rxmit && tp->snd_nxt != tp->snd_max) || 1589 (tp->snd_nxt != tp->snd_una))) { 1590 if (tcp_timer_active(tp, TT_PERSIST)) { 1591 tcp_timer_activate(tp, TT_PERSIST, 0); 1592 tp->t_rxtshift = 0; 1593 } 1594 tcp_timer_activate(tp, TT_REXMT, TP_RXTCUR(tp)); 1595 } else if (len == 0 && sbavail(&so->so_snd) && 1596 !tcp_timer_active(tp, TT_REXMT) && 1597 !tcp_timer_active(tp, TT_PERSIST)) { 1598 /* 1599 * Avoid a situation where we do not set persist timer 1600 * after a zero window condition. For example: 1601 * 1) A -> B: packet with enough data to fill the window 1602 * 2) B -> A: ACK for #1 + new data (0 window 1603 * advertisement) 1604 * 3) A -> B: ACK for #2, 0 len packet 1605 * 1606 * In this case, A will not activate the persist timer, 1607 * because it chose to send a packet. Unless tcp_output 1608 * is called for some other reason (delayed ack timer, 1609 * another input packet from B, socket syscall), A will 1610 * not send zero window probes. 1611 * 1612 * So, if you send a 0-length packet, but there is data 1613 * in the socket buffer, and neither the rexmt or 1614 * persist timer is already set, then activate the 1615 * persist timer. 1616 */ 1617 tp->t_rxtshift = 0; 1618 tcp_setpersist(tp); 1619 } 1620 } else { 1621 /* 1622 * Persist case, update snd_max but since we are in 1623 * persist mode (no window) we do not update snd_nxt. 1624 */ 1625 int xlen = len; 1626 if (flags & TH_SYN) 1627 ++xlen; 1628 if (flags & TH_FIN) { 1629 ++xlen; 1630 tp->t_flags |= TF_SENTFIN; 1631 } 1632 if (SEQ_GT(tp->snd_nxt + xlen, tp->snd_max)) 1633 tp->snd_max = tp->snd_nxt + xlen; 1634 } 1635 if ((error == 0) && 1636 (tp->rcv_numsacks > 0) && 1637 TCPS_HAVEESTABLISHED(tp->t_state) && 1638 (tp->t_flags & TF_SACK_PERMIT)) { 1639 /* Clean up any DSACK's sent */ 1640 tcp_clean_dsack_blocks(tp); 1641 } 1642 if ((error == 0) && 1643 sack_rxmit && 1644 SEQ_LT(tp->snd_nxt, SEQ_MIN(p->rxmit, p->end))) { 1645 /* 1646 * When transmitting from SACK scoreboard 1647 * after an RTO, pull snd_nxt along. 1648 */ 1649 tp->snd_nxt = SEQ_MIN(p->rxmit, p->end); 1650 } 1651 if (error) { 1652 /* 1653 * We know that the packet was lost, so back out the 1654 * sequence number advance, if any. 1655 * 1656 * If the error is EPERM the packet got blocked by the 1657 * local firewall. Normally we should terminate the 1658 * connection but the blocking may have been spurious 1659 * due to a firewall reconfiguration cycle. So we treat 1660 * it like a packet loss and let the retransmit timer and 1661 * timeouts do their work over time. 1662 * XXX: It is a POLA question whether calling tcp_drop right 1663 * away would be the really correct behavior instead. 1664 */ 1665 if (((tp->t_flags & TF_FORCEDATA) == 0 || 1666 !tcp_timer_active(tp, TT_PERSIST)) && 1667 ((flags & TH_SYN) == 0) && 1668 (error != EPERM)) { 1669 if (sack_rxmit) { 1670 p->rxmit = SEQ_MIN(p->end, p->rxmit) - len; 1671 tp->sackhint.sack_bytes_rexmit -= len; 1672 KASSERT(tp->sackhint.sack_bytes_rexmit >= 0, 1673 ("sackhint bytes rtx >= 0")); 1674 KASSERT((flags & TH_FIN) == 0, 1675 ("error while FIN with SACK rxmit")); 1676 } else { 1677 tp->snd_nxt -= len; 1678 if (flags & TH_FIN) 1679 tp->snd_nxt--; 1680 } 1681 if (IN_RECOVERY(tp->t_flags)) 1682 tp->sackhint.prr_out -= len; 1683 } 1684 SOCK_SENDBUF_UNLOCK_ASSERT(so); /* Check gotos. */ 1685 switch (error) { 1686 case EACCES: 1687 case EPERM: 1688 tp->t_softerror = error; 1689 return (error); 1690 case ENOBUFS: 1691 TCP_XMIT_TIMER_ASSERT(tp, len, flags); 1692 tp->snd_cwnd = tcp_maxseg(tp); 1693 return (0); 1694 case EMSGSIZE: 1695 /* 1696 * For some reason the interface we used initially 1697 * to send segments changed to another or lowered 1698 * its MTU. 1699 * If TSO was active we either got an interface 1700 * without TSO capabilits or TSO was turned off. 1701 * If we obtained mtu from ip_output() then update 1702 * it and try again. 1703 */ 1704 if (tso) 1705 tp->t_flags &= ~TF_TSO; 1706 if (mtu != 0) { 1707 tcp_mss_update(tp, -1, mtu, NULL, NULL); 1708 goto again; 1709 } 1710 return (error); 1711 case EHOSTDOWN: 1712 case EHOSTUNREACH: 1713 case ENETDOWN: 1714 case ENETUNREACH: 1715 if (TCPS_HAVERCVDSYN(tp->t_state)) { 1716 tp->t_softerror = error; 1717 return (0); 1718 } 1719 /* FALLTHROUGH */ 1720 default: 1721 return (error); 1722 } 1723 } 1724 TCPSTAT_INC(tcps_sndtotal); 1725 1726 /* 1727 * Data sent (as far as we can tell). 1728 * If this advertises a larger window than any other segment, 1729 * then remember the size of the advertised window. 1730 * Any pending ACK has now been sent. 1731 */ 1732 if (SEQ_GT(tp->rcv_nxt + recwin, tp->rcv_adv)) 1733 tp->rcv_adv = tp->rcv_nxt + recwin; 1734 tp->last_ack_sent = tp->rcv_nxt; 1735 tp->t_flags &= ~(TF_ACKNOW | TF_DELACK); 1736 if (tcp_timer_active(tp, TT_DELACK)) 1737 tcp_timer_activate(tp, TT_DELACK, 0); 1738 if (sendalot) 1739 goto again; 1740 return (0); 1741 } 1742 1743 void 1744 tcp_setpersist(struct tcpcb *tp) 1745 { 1746 int t = ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1; 1747 int tt; 1748 int maxunacktime; 1749 1750 tp->t_flags &= ~TF_PREVVALID; 1751 if (tcp_timer_active(tp, TT_REXMT)) 1752 panic("tcp_setpersist: retransmit pending"); 1753 /* 1754 * If the state is already closed, don't bother. 1755 */ 1756 if (tp->t_state == TCPS_CLOSED) 1757 return; 1758 1759 /* 1760 * Start/restart persistence timer. 1761 */ 1762 TCPT_RANGESET(tt, t * tcp_backoff[tp->t_rxtshift], 1763 tcp_persmin, tcp_persmax); 1764 if (TP_MAXUNACKTIME(tp) && tp->t_acktime) { 1765 maxunacktime = tp->t_acktime + TP_MAXUNACKTIME(tp) - ticks; 1766 if (maxunacktime < 1) 1767 maxunacktime = 1; 1768 if (maxunacktime < tt) 1769 tt = maxunacktime; 1770 } 1771 tcp_timer_activate(tp, TT_PERSIST, tt); 1772 if (tp->t_rxtshift < V_tcp_retries) 1773 tp->t_rxtshift++; 1774 } 1775 1776 /* 1777 * Insert TCP options according to the supplied parameters to the place 1778 * optp in a consistent way. Can handle unaligned destinations. 1779 * 1780 * The order of the option processing is crucial for optimal packing and 1781 * alignment for the scarce option space. 1782 * 1783 * The optimal order for a SYN/SYN-ACK segment is: 1784 * MSS (4) + NOP (1) + Window scale (3) + SACK permitted (2) + 1785 * Timestamp (10) + Signature (18) = 38 bytes out of a maximum of 40. 1786 * 1787 * The SACK options should be last. SACK blocks consume 8*n+2 bytes. 1788 * So a full size SACK blocks option is 34 bytes (with 4 SACK blocks). 1789 * At minimum we need 10 bytes (to generate 1 SACK block). If both 1790 * TCP Timestamps (12 bytes) and TCP Signatures (18 bytes) are present, 1791 * we only have 10 bytes for SACK options (40 - (12 + 18)). 1792 */ 1793 int 1794 tcp_addoptions(struct tcpopt *to, u_char *optp) 1795 { 1796 u_int32_t mask, optlen = 0; 1797 1798 for (mask = 1; mask < TOF_MAXOPT; mask <<= 1) { 1799 if ((to->to_flags & mask) != mask) 1800 continue; 1801 if (optlen == TCP_MAXOLEN) 1802 break; 1803 switch (to->to_flags & mask) { 1804 case TOF_MSS: 1805 while (optlen % 4) { 1806 optlen += TCPOLEN_NOP; 1807 *optp++ = TCPOPT_NOP; 1808 } 1809 if (TCP_MAXOLEN - optlen < TCPOLEN_MAXSEG) 1810 continue; 1811 optlen += TCPOLEN_MAXSEG; 1812 *optp++ = TCPOPT_MAXSEG; 1813 *optp++ = TCPOLEN_MAXSEG; 1814 to->to_mss = htons(to->to_mss); 1815 bcopy((u_char *)&to->to_mss, optp, sizeof(to->to_mss)); 1816 optp += sizeof(to->to_mss); 1817 break; 1818 case TOF_SCALE: 1819 while (!optlen || optlen % 2 != 1) { 1820 optlen += TCPOLEN_NOP; 1821 *optp++ = TCPOPT_NOP; 1822 } 1823 if (TCP_MAXOLEN - optlen < TCPOLEN_WINDOW) 1824 continue; 1825 optlen += TCPOLEN_WINDOW; 1826 *optp++ = TCPOPT_WINDOW; 1827 *optp++ = TCPOLEN_WINDOW; 1828 *optp++ = to->to_wscale; 1829 break; 1830 case TOF_SACKPERM: 1831 while (optlen % 2) { 1832 optlen += TCPOLEN_NOP; 1833 *optp++ = TCPOPT_NOP; 1834 } 1835 if (TCP_MAXOLEN - optlen < TCPOLEN_SACK_PERMITTED) 1836 continue; 1837 optlen += TCPOLEN_SACK_PERMITTED; 1838 *optp++ = TCPOPT_SACK_PERMITTED; 1839 *optp++ = TCPOLEN_SACK_PERMITTED; 1840 break; 1841 case TOF_TS: 1842 while (!optlen || optlen % 4 != 2) { 1843 optlen += TCPOLEN_NOP; 1844 *optp++ = TCPOPT_NOP; 1845 } 1846 if (TCP_MAXOLEN - optlen < TCPOLEN_TIMESTAMP) 1847 continue; 1848 optlen += TCPOLEN_TIMESTAMP; 1849 *optp++ = TCPOPT_TIMESTAMP; 1850 *optp++ = TCPOLEN_TIMESTAMP; 1851 to->to_tsval = htonl(to->to_tsval); 1852 to->to_tsecr = htonl(to->to_tsecr); 1853 bcopy((u_char *)&to->to_tsval, optp, sizeof(to->to_tsval)); 1854 optp += sizeof(to->to_tsval); 1855 bcopy((u_char *)&to->to_tsecr, optp, sizeof(to->to_tsecr)); 1856 optp += sizeof(to->to_tsecr); 1857 break; 1858 case TOF_SIGNATURE: 1859 { 1860 int siglen = TCPOLEN_SIGNATURE - 2; 1861 1862 while (!optlen || optlen % 4 != 2) { 1863 optlen += TCPOLEN_NOP; 1864 *optp++ = TCPOPT_NOP; 1865 } 1866 if (TCP_MAXOLEN - optlen < TCPOLEN_SIGNATURE) { 1867 to->to_flags &= ~TOF_SIGNATURE; 1868 continue; 1869 } 1870 optlen += TCPOLEN_SIGNATURE; 1871 *optp++ = TCPOPT_SIGNATURE; 1872 *optp++ = TCPOLEN_SIGNATURE; 1873 to->to_signature = optp; 1874 while (siglen--) 1875 *optp++ = 0; 1876 break; 1877 } 1878 case TOF_SACK: 1879 { 1880 int sackblks = 0; 1881 struct sackblk *sack = (struct sackblk *)to->to_sacks; 1882 tcp_seq sack_seq; 1883 1884 while (!optlen || optlen % 4 != 2) { 1885 optlen += TCPOLEN_NOP; 1886 *optp++ = TCPOPT_NOP; 1887 } 1888 if (TCP_MAXOLEN - optlen < TCPOLEN_SACKHDR + TCPOLEN_SACK) 1889 continue; 1890 optlen += TCPOLEN_SACKHDR; 1891 *optp++ = TCPOPT_SACK; 1892 sackblks = min(to->to_nsacks, 1893 (TCP_MAXOLEN - optlen) / TCPOLEN_SACK); 1894 *optp++ = TCPOLEN_SACKHDR + sackblks * TCPOLEN_SACK; 1895 while (sackblks--) { 1896 sack_seq = htonl(sack->start); 1897 bcopy((u_char *)&sack_seq, optp, sizeof(sack_seq)); 1898 optp += sizeof(sack_seq); 1899 sack_seq = htonl(sack->end); 1900 bcopy((u_char *)&sack_seq, optp, sizeof(sack_seq)); 1901 optp += sizeof(sack_seq); 1902 optlen += TCPOLEN_SACK; 1903 sack++; 1904 } 1905 TCPSTAT_INC(tcps_sack_send_blocks); 1906 break; 1907 } 1908 case TOF_FASTOPEN: 1909 { 1910 int total_len; 1911 1912 /* XXX is there any point to aligning this option? */ 1913 total_len = TCPOLEN_FAST_OPEN_EMPTY + to->to_tfo_len; 1914 if (TCP_MAXOLEN - optlen < total_len) { 1915 to->to_flags &= ~TOF_FASTOPEN; 1916 continue; 1917 } 1918 *optp++ = TCPOPT_FAST_OPEN; 1919 *optp++ = total_len; 1920 if (to->to_tfo_len > 0) { 1921 bcopy(to->to_tfo_cookie, optp, to->to_tfo_len); 1922 optp += to->to_tfo_len; 1923 } 1924 optlen += total_len; 1925 break; 1926 } 1927 default: 1928 panic("%s: unknown TCP option type", __func__); 1929 break; 1930 } 1931 } 1932 1933 /* Terminate and pad TCP options to a 4 byte boundary. */ 1934 if (optlen % 4) { 1935 optlen += TCPOLEN_EOL; 1936 *optp++ = TCPOPT_EOL; 1937 } 1938 /* 1939 * According to RFC 793 (STD0007): 1940 * "The content of the header beyond the End-of-Option option 1941 * must be header padding (i.e., zero)." 1942 * and later: "The padding is composed of zeros." 1943 */ 1944 while (optlen % 4) { 1945 optlen += TCPOLEN_PAD; 1946 *optp++ = TCPOPT_PAD; 1947 } 1948 1949 KASSERT(optlen <= TCP_MAXOLEN, ("%s: TCP options too long", __func__)); 1950 return (optlen); 1951 } 1952 1953 /* 1954 * This is a copy of m_copym(), taking the TSO segment size/limit 1955 * constraints into account, and advancing the sndptr as it goes. 1956 */ 1957 struct mbuf * 1958 tcp_m_copym(struct mbuf *m, int32_t off0, int32_t *plen, 1959 int32_t seglimit, int32_t segsize, struct sockbuf *sb, bool hw_tls) 1960 { 1961 #ifdef KERN_TLS 1962 struct ktls_session *tls, *ntls; 1963 struct mbuf *start __diagused; 1964 #endif 1965 struct mbuf *n, **np; 1966 struct mbuf *top; 1967 int32_t off = off0; 1968 int32_t len = *plen; 1969 int32_t fragsize; 1970 int32_t len_cp = 0; 1971 int32_t *pkthdrlen; 1972 uint32_t mlen, frags; 1973 bool copyhdr; 1974 1975 KASSERT(off >= 0, ("tcp_m_copym, negative off %d", off)); 1976 KASSERT(len >= 0, ("tcp_m_copym, negative len %d", len)); 1977 if (off == 0 && m->m_flags & M_PKTHDR) 1978 copyhdr = true; 1979 else 1980 copyhdr = false; 1981 while (off > 0) { 1982 KASSERT(m != NULL, ("tcp_m_copym, offset > size of mbuf chain")); 1983 if (off < m->m_len) 1984 break; 1985 off -= m->m_len; 1986 if ((sb) && (m == sb->sb_sndptr)) { 1987 sb->sb_sndptroff += m->m_len; 1988 sb->sb_sndptr = m->m_next; 1989 } 1990 m = m->m_next; 1991 } 1992 np = ⊤ 1993 top = NULL; 1994 pkthdrlen = NULL; 1995 #ifdef KERN_TLS 1996 if (hw_tls && (m->m_flags & M_EXTPG)) 1997 tls = m->m_epg_tls; 1998 else 1999 tls = NULL; 2000 start = m; 2001 #endif 2002 while (len > 0) { 2003 if (m == NULL) { 2004 KASSERT(len == M_COPYALL, 2005 ("tcp_m_copym, length > size of mbuf chain")); 2006 *plen = len_cp; 2007 if (pkthdrlen != NULL) 2008 *pkthdrlen = len_cp; 2009 break; 2010 } 2011 #ifdef KERN_TLS 2012 if (hw_tls) { 2013 if (m->m_flags & M_EXTPG) 2014 ntls = m->m_epg_tls; 2015 else 2016 ntls = NULL; 2017 2018 /* 2019 * Avoid mixing TLS records with handshake 2020 * data or TLS records from different 2021 * sessions. 2022 */ 2023 if (tls != ntls) { 2024 MPASS(m != start); 2025 *plen = len_cp; 2026 if (pkthdrlen != NULL) 2027 *pkthdrlen = len_cp; 2028 break; 2029 } 2030 } 2031 #endif 2032 mlen = min(len, m->m_len - off); 2033 if (seglimit) { 2034 /* 2035 * For M_EXTPG mbufs, add 3 segments 2036 * + 1 in case we are crossing page boundaries 2037 * + 2 in case the TLS hdr/trailer are used 2038 * It is cheaper to just add the segments 2039 * than it is to take the cache miss to look 2040 * at the mbuf ext_pgs state in detail. 2041 */ 2042 if (m->m_flags & M_EXTPG) { 2043 fragsize = min(segsize, PAGE_SIZE); 2044 frags = 3; 2045 } else { 2046 fragsize = segsize; 2047 frags = 0; 2048 } 2049 2050 /* Break if we really can't fit anymore. */ 2051 if ((frags + 1) >= seglimit) { 2052 *plen = len_cp; 2053 if (pkthdrlen != NULL) 2054 *pkthdrlen = len_cp; 2055 break; 2056 } 2057 2058 /* 2059 * Reduce size if you can't copy the whole 2060 * mbuf. If we can't copy the whole mbuf, also 2061 * adjust len so the loop will end after this 2062 * mbuf. 2063 */ 2064 if ((frags + howmany(mlen, fragsize)) >= seglimit) { 2065 mlen = (seglimit - frags - 1) * fragsize; 2066 len = mlen; 2067 *plen = len_cp + len; 2068 if (pkthdrlen != NULL) 2069 *pkthdrlen = *plen; 2070 } 2071 frags += howmany(mlen, fragsize); 2072 if (frags == 0) 2073 frags++; 2074 seglimit -= frags; 2075 KASSERT(seglimit > 0, 2076 ("%s: seglimit went too low", __func__)); 2077 } 2078 if (copyhdr) 2079 n = m_gethdr(M_NOWAIT, m->m_type); 2080 else 2081 n = m_get(M_NOWAIT, m->m_type); 2082 *np = n; 2083 if (n == NULL) 2084 goto nospace; 2085 if (copyhdr) { 2086 if (!m_dup_pkthdr(n, m, M_NOWAIT)) 2087 goto nospace; 2088 if (len == M_COPYALL) 2089 n->m_pkthdr.len -= off0; 2090 else 2091 n->m_pkthdr.len = len; 2092 pkthdrlen = &n->m_pkthdr.len; 2093 copyhdr = false; 2094 } 2095 n->m_len = mlen; 2096 len_cp += n->m_len; 2097 if (m->m_flags & (M_EXT | M_EXTPG)) { 2098 n->m_data = m->m_data + off; 2099 mb_dupcl(n, m); 2100 } else 2101 bcopy(mtod(m, caddr_t)+off, mtod(n, caddr_t), 2102 (u_int)n->m_len); 2103 2104 if (sb && (sb->sb_sndptr == m) && 2105 ((n->m_len + off) >= m->m_len) && m->m_next) { 2106 sb->sb_sndptroff += m->m_len; 2107 sb->sb_sndptr = m->m_next; 2108 } 2109 off = 0; 2110 if (len != M_COPYALL) { 2111 len -= n->m_len; 2112 } 2113 m = m->m_next; 2114 np = &n->m_next; 2115 } 2116 return (top); 2117 nospace: 2118 m_freem(top); 2119 return (NULL); 2120 } 2121 2122 void 2123 tcp_sndbuf_autoscale(struct tcpcb *tp, struct socket *so, uint32_t sendwin) 2124 { 2125 2126 /* 2127 * Automatic sizing of send socket buffer. Often the send buffer 2128 * size is not optimally adjusted to the actual network conditions 2129 * at hand (delay bandwidth product). Setting the buffer size too 2130 * small limits throughput on links with high bandwidth and high 2131 * delay (eg. trans-continental/oceanic links). Setting the 2132 * buffer size too big consumes too much real kernel memory, 2133 * especially with many connections on busy servers. 2134 * 2135 * The criteria to step up the send buffer one notch are: 2136 * 1. receive window of remote host is larger than send buffer 2137 * (with a fudge factor of 5/4th); 2138 * 2. send buffer is filled to 7/8th with data (so we actually 2139 * have data to make use of it); 2140 * 3. send buffer fill has not hit maximal automatic size; 2141 * 4. our send window (slow start and cogestion controlled) is 2142 * larger than sent but unacknowledged data in send buffer. 2143 * 2144 * The remote host receive window scaling factor may limit the 2145 * growing of the send buffer before it reaches its allowed 2146 * maximum. 2147 * 2148 * It scales directly with slow start or congestion window 2149 * and does at most one step per received ACK. This fast 2150 * scaling has the drawback of growing the send buffer beyond 2151 * what is strictly necessary to make full use of a given 2152 * delay*bandwidth product. However testing has shown this not 2153 * to be much of an problem. At worst we are trading wasting 2154 * of available bandwidth (the non-use of it) for wasting some 2155 * socket buffer memory. 2156 * 2157 * TODO: Shrink send buffer during idle periods together 2158 * with congestion window. Requires another timer. Has to 2159 * wait for upcoming tcp timer rewrite. 2160 * 2161 * XXXGL: should there be used sbused() or sbavail()? 2162 */ 2163 if (V_tcp_do_autosndbuf && so->so_snd.sb_flags & SB_AUTOSIZE) { 2164 int lowat; 2165 2166 lowat = V_tcp_sendbuf_auto_lowat ? so->so_snd.sb_lowat : 0; 2167 if ((tp->snd_wnd / 4 * 5) >= so->so_snd.sb_hiwat - lowat && 2168 sbused(&so->so_snd) >= 2169 (so->so_snd.sb_hiwat / 8 * 7) - lowat && 2170 sbused(&so->so_snd) < V_tcp_autosndbuf_max && 2171 sendwin >= (sbused(&so->so_snd) - 2172 (tp->snd_nxt - tp->snd_una))) { 2173 if (!sbreserve_locked(so, SO_SND, 2174 min(so->so_snd.sb_hiwat + V_tcp_autosndbuf_inc, 2175 V_tcp_autosndbuf_max), curthread)) 2176 so->so_snd.sb_flags &= ~SB_AUTOSIZE; 2177 } 2178 } 2179 } 2180