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> 103 104 VNET_DEFINE(int, path_mtu_discovery) = 1; 105 SYSCTL_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"); 108 109 VNET_DEFINE(int, tcp_do_tso) = 1; 110 SYSCTL_INT(_net_inet_tcp, OID_AUTO, tso, CTLFLAG_VNET | CTLFLAG_RW, 111 &VNET_NAME(tcp_do_tso), 0, 112 "Enable TCP Segmentation Offload"); 113 114 VNET_DEFINE(int, tcp_sendspace) = 1024*32; 115 #define V_tcp_sendspace VNET(tcp_sendspace) 116 SYSCTL_INT(_net_inet_tcp, TCPCTL_SENDSPACE, sendspace, CTLFLAG_VNET | CTLFLAG_RW, 117 &VNET_NAME(tcp_sendspace), 0, "Initial send socket buffer size"); 118 119 VNET_DEFINE(int, tcp_do_autosndbuf) = 1; 120 SYSCTL_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"); 123 124 VNET_DEFINE(int, tcp_autosndbuf_inc) = 8*1024; 125 SYSCTL_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"); 128 129 VNET_DEFINE(int, tcp_autosndbuf_max) = 2*1024*1024; 130 SYSCTL_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"); 133 134 VNET_DEFINE(int, tcp_sendbuf_auto_lowat) = 0; 135 #define V_tcp_sendbuf_auto_lowat VNET(tcp_sendbuf_auto_lowat) 136 SYSCTL_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 */ 154 void 155 hhook_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 */ 176 void 177 cc_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 */ 188 int 189 tcp_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 unsigned ipsec_optlen = 0; 205 int idle, sendalot, curticks; 206 int sack_bytes_rxmt; 207 struct sackhole *p; 208 int tso, mtu; 209 struct tcpopt to; 210 struct udphdr *udp = NULL; 211 struct tcp_log_buffer *lgb; 212 unsigned int wanted_cookie = 0; 213 unsigned int dont_sendalot = 0; 214 bool sack_rxmit; 215 #ifdef INET6 216 struct ip6_hdr *ip6 = NULL; 217 const bool isipv6 = (inp->inp_vflag & INP_IPV6) != 0; 218 #endif 219 #ifdef KERN_TLS 220 const bool hw_tls = tp->t_nic_ktls_xmit != 0; 221 #else 222 const bool hw_tls = false; 223 #endif 224 225 NET_EPOCH_ASSERT(); 226 INP_WLOCK_ASSERT(inp); 227 228 #ifdef TCP_OFFLOAD 229 if (tp->t_flags & TF_TOE) 230 return (tcp_offload_output(tp)); 231 #endif 232 233 /* 234 * For TFO connections in SYN_SENT or SYN_RECEIVED, 235 * only allow the initial SYN or SYN|ACK and those sent 236 * by the retransmit timer. 237 */ 238 if ((tp->t_flags & TF_FASTOPEN) && 239 ((tp->t_state == TCPS_SYN_SENT) || 240 (tp->t_state == TCPS_SYN_RECEIVED)) && 241 SEQ_GT(tp->snd_max, tp->snd_una) && /* SYN or SYN|ACK sent */ 242 (tp->snd_nxt != tp->snd_una)) /* not a retransmit */ 243 return (0); 244 245 /* 246 * Determine length of data that should be transmitted, 247 * and flags that will be used. 248 * If there is some data or critical controls (SYN, RST) 249 * to send, then transmit; otherwise, investigate further. 250 */ 251 idle = (tp->t_flags & TF_LASTIDLE) || (tp->snd_max == tp->snd_una); 252 if (idle && (((ticks - tp->t_rcvtime) >= tp->t_rxtcur) || 253 (tp->t_sndtime && ((ticks - tp->t_sndtime) >= tp->t_rxtcur)))) 254 cc_after_idle(tp); 255 tp->t_flags &= ~TF_LASTIDLE; 256 if (idle) { 257 if (tp->t_flags & TF_MORETOCOME) { 258 tp->t_flags |= TF_LASTIDLE; 259 idle = 0; 260 } 261 } 262 again: 263 sendwin = 0; 264 /* 265 * If we've recently taken a timeout, snd_max will be greater than 266 * snd_nxt. There may be SACK information that allows us to avoid 267 * resending already delivered data. Adjust snd_nxt accordingly. 268 */ 269 if ((tp->t_flags & TF_SACK_PERMIT) && 270 (tp->sackhint.nexthole != NULL) && 271 !IN_FASTRECOVERY(tp->t_flags)) { 272 sendwin = tcp_sack_adjust(tp); 273 } 274 sendalot = 0; 275 tso = 0; 276 mtu = 0; 277 off = tp->snd_nxt - tp->snd_una; 278 sendwin = min(tp->snd_wnd, tp->snd_cwnd + sendwin); 279 280 flags = tcp_outflags[tp->t_state]; 281 /* 282 * Send any SACK-generated retransmissions. If we're explicitly trying 283 * to send out new data (when sendalot is 1), bypass this function. 284 * If we retransmit in fast recovery mode, decrement snd_cwnd, since 285 * we're replacing a (future) new transmission with a retransmission 286 * now, and we previously incremented snd_cwnd in tcp_input(). 287 */ 288 /* 289 * Still in sack recovery , reset rxmit flag to zero. 290 */ 291 sack_bytes_rxmt = 0; 292 len = 0; 293 if ((tp->t_flags & TF_SACK_PERMIT) && 294 (IN_FASTRECOVERY(tp->t_flags) || 295 (SEQ_LT(tp->snd_nxt, tp->snd_max) && (tp->t_dupacks >= tcprexmtthresh))) && 296 (p = tcp_sack_output(tp, &sack_bytes_rxmt))) { 297 int32_t cwin; 298 299 if (IN_FASTRECOVERY(tp->t_flags)) { 300 cwin = imax(sendwin - tcp_compute_pipe(tp), 0); 301 } else { 302 cwin = imax(sendwin - off, 0); 303 } 304 /* Do not retransmit SACK segments beyond snd_recover */ 305 if (SEQ_GT(p->end, tp->snd_recover)) { 306 /* 307 * (At least) part of sack hole extends beyond 308 * snd_recover. Check to see if we can rexmit data 309 * for this hole. 310 */ 311 if (SEQ_GEQ(p->rxmit, tp->snd_recover)) { 312 /* 313 * Can't rexmit any more data for this hole. 314 * That data will be rexmitted in the next 315 * sack recovery episode, when snd_recover 316 * moves past p->rxmit. 317 */ 318 p = NULL; 319 sack_rxmit = false; 320 goto after_sack_rexmit; 321 } else { 322 /* Can rexmit part of the current hole */ 323 len = SEQ_SUB(tp->snd_recover, p->rxmit); 324 if (cwin <= len) { 325 len = cwin; 326 } else { 327 sendalot = 1; 328 } 329 } 330 } else { 331 len = SEQ_SUB(p->end, p->rxmit); 332 if (cwin <= len) { 333 len = cwin; 334 } else { 335 sendalot = 1; 336 } 337 } 338 /* we could have transmitted from the scoreboard, 339 * but sendwin (expected flightsize) - pipe didn't 340 * allow any transmission. 341 * Bypass recalculating the possible transmission 342 * length further down by setting sack_rxmit. 343 * Wouldn't be here if there would have been 344 * nothing in the scoreboard to transmit. 345 */ 346 if (len > 0) { 347 off = SEQ_SUB(p->rxmit, tp->snd_una); 348 KASSERT(off >= 0,("%s: sack block to the left of una : %d", 349 __func__, off)); 350 } 351 sack_rxmit = true; 352 } else { 353 p = NULL; 354 sack_rxmit = false; 355 } 356 after_sack_rexmit: 357 /* 358 * Get standard flags, and add SYN or FIN if requested by 'hidden' 359 * state flags. 360 */ 361 if (tp->t_flags & TF_NEEDFIN) 362 flags |= TH_FIN; 363 if (tp->t_flags & TF_NEEDSYN) 364 flags |= TH_SYN; 365 366 SOCK_SENDBUF_LOCK(so); 367 /* 368 * If in persist timeout with window of 0, send 1 byte. 369 * Otherwise, if window is small but nonzero 370 * and timer expired, we will send what we can 371 * and go to transmit state. 372 */ 373 if (tp->t_flags & TF_FORCEDATA) { 374 if (sendwin == 0) { 375 /* 376 * If we still have some data to send, then 377 * clear the FIN bit. Usually this would 378 * happen below when it realizes that we 379 * aren't sending all the data. However, 380 * if we have exactly 1 byte of unsent data, 381 * then it won't clear the FIN bit below, 382 * and if we are in persist state, we wind 383 * up sending the packet without recording 384 * that we sent the FIN bit. 385 * 386 * We can't just blindly clear the FIN bit, 387 * because if we don't have any more data 388 * to send then the probe will be the FIN 389 * itself. 390 */ 391 if (off < sbused(&so->so_snd)) 392 flags &= ~TH_FIN; 393 sendwin = 1; 394 } else { 395 tcp_timer_activate(tp, TT_PERSIST, 0); 396 tp->t_rxtshift = 0; 397 } 398 } 399 400 /* 401 * If snd_nxt == snd_max and we have transmitted a FIN, the 402 * offset will be > 0 even if so_snd.sb_cc is 0, resulting in 403 * a negative length. This can also occur when TCP opens up 404 * its congestion window while receiving additional duplicate 405 * acks after fast-retransmit because TCP will reset snd_nxt 406 * to snd_max after the fast-retransmit. 407 * 408 * In the normal retransmit-FIN-only case, however, snd_nxt will 409 * be set to snd_una, the offset will be 0, and the length may 410 * wind up 0. 411 * 412 * If sack_rxmit is true we are retransmitting from the scoreboard 413 * in which case len is already set. 414 */ 415 if (!sack_rxmit) { 416 if ((sack_bytes_rxmt == 0) || SEQ_LT(tp->snd_nxt, tp->snd_max)) { 417 len = imin(sbavail(&so->so_snd), sendwin) - off; 418 } else { 419 /* 420 * We are inside of a SACK recovery episode and are 421 * sending new data, having retransmitted all the 422 * data possible in the scoreboard. 423 */ 424 len = imax( 425 imin(sbavail(&so->so_snd), sendwin) - 426 imax(tcp_compute_pipe(tp), off), 0); 427 } 428 } 429 430 /* 431 * Lop off SYN bit if it has already been sent. However, if this 432 * is SYN-SENT state and if segment contains data and if we don't 433 * know that foreign host supports TAO, suppress sending segment. 434 */ 435 if ((flags & TH_SYN) && SEQ_GT(tp->snd_nxt, tp->snd_una)) { 436 if (tp->t_state != TCPS_SYN_RECEIVED) 437 flags &= ~TH_SYN; 438 /* 439 * When sending additional segments following a TFO SYN|ACK, 440 * do not include the SYN bit. 441 */ 442 if ((tp->t_flags & TF_FASTOPEN) && 443 (tp->t_state == TCPS_SYN_RECEIVED)) 444 flags &= ~TH_SYN; 445 off--, len++; 446 } 447 448 /* 449 * Be careful not to send data and/or FIN on SYN segments. 450 * This measure is needed to prevent interoperability problems 451 * with not fully conformant TCP implementations. 452 */ 453 if ((flags & TH_SYN) && (tp->t_flags & TF_NOOPT)) { 454 len = 0; 455 flags &= ~TH_FIN; 456 } 457 458 /* 459 * On TFO sockets, ensure no data is sent in the following cases: 460 * 461 * - When retransmitting SYN|ACK on a passively-created socket 462 * 463 * - When retransmitting SYN on an actively created socket 464 * 465 * - When sending a zero-length cookie (cookie request) on an 466 * actively created socket 467 * 468 * - When the socket is in the CLOSED state (RST is being sent) 469 */ 470 if ((tp->t_flags & TF_FASTOPEN) && 471 (((flags & TH_SYN) && (tp->t_rxtshift > 0)) || 472 ((tp->t_state == TCPS_SYN_SENT) && 473 (tp->t_tfo_client_cookie_len == 0)) || 474 (flags & TH_RST))) 475 len = 0; 476 477 /* Without fast-open there should never be data sent on a SYN. */ 478 if ((flags & TH_SYN) && !(tp->t_flags & TF_FASTOPEN)) { 479 len = 0; 480 } 481 482 if (len <= 0) { 483 /* 484 * If FIN has been sent but not acked, 485 * but we haven't been called to retransmit, 486 * len will be < 0. Otherwise, window shrank 487 * after we sent into it. If window shrank to 0, 488 * cancel pending retransmit, pull snd_nxt back 489 * to (closed) window, and set the persist timer 490 * if it isn't already going. If the window didn't 491 * close completely, just wait for an ACK. 492 * 493 * We also do a general check here to ensure that 494 * we will set the persist timer when we have data 495 * to send, but a 0-byte window. This makes sure 496 * the persist timer is set even if the packet 497 * hits one of the "goto send" lines below. 498 */ 499 len = 0; 500 if ((sendwin == 0) && (TCPS_HAVEESTABLISHED(tp->t_state)) && 501 (off < (int) sbavail(&so->so_snd)) && 502 !tcp_timer_active(tp, TT_PERSIST)) { 503 tcp_timer_activate(tp, TT_REXMT, 0); 504 tp->t_rxtshift = 0; 505 tp->snd_nxt = tp->snd_una; 506 if (!tcp_timer_active(tp, TT_PERSIST)) 507 tcp_setpersist(tp); 508 } 509 } 510 511 /* len will be >= 0 after this point. */ 512 KASSERT(len >= 0, ("[%s:%d]: len < 0", __func__, __LINE__)); 513 514 tcp_sndbuf_autoscale(tp, so, sendwin); 515 516 /* 517 * Decide if we can use TCP Segmentation Offloading (if supported by 518 * hardware). 519 * 520 * TSO may only be used if we are in a pure bulk sending state. The 521 * presence of TCP-MD5, IP options (IPsec), and possibly SACK 522 * retransmits prevent using TSO. With TSO the TCP header is the same 523 * (except for the sequence number) for all generated packets. This 524 * makes it impossible to transmit any options which vary per generated 525 * segment or packet. 526 * 527 * IPv4 handling has a clear separation of ip options and ip header 528 * flags while IPv6 combines both in in6p_outputopts. ip6_optlen() does 529 * the right thing below to provide length of just ip options and thus 530 * checking for ipoptlen is enough to decide if ip options are present. 531 */ 532 #if defined(IPSEC) || defined(IPSEC_SUPPORT) 533 /* 534 * Pre-calculate here as we save another lookup into the darknesses 535 * of IPsec that way and can actually decide if TSO is ok. 536 */ 537 #ifdef INET6 538 if (isipv6 && IPSEC_ENABLED(ipv6)) 539 ipsec_optlen = IPSEC_HDRSIZE(ipv6, inp); 540 #ifdef INET 541 else 542 #endif 543 #endif /* INET6 */ 544 #ifdef INET 545 if (IPSEC_ENABLED(ipv4)) 546 ipsec_optlen = IPSEC_HDRSIZE(ipv4, inp); 547 #endif /* INET */ 548 #endif /* IPSEC */ 549 #ifdef INET6 550 if (isipv6) 551 ipoptlen = ip6_optlen(inp); 552 else 553 #endif 554 if (inp->inp_options) 555 ipoptlen = inp->inp_options->m_len - 556 offsetof(struct ipoption, ipopt_list); 557 else 558 ipoptlen = 0; 559 ipoptlen += ipsec_optlen; 560 561 if ((tp->t_flags & TF_TSO) && V_tcp_do_tso && len > tp->t_maxseg && 562 (tp->t_port == 0) && 563 ((tp->t_flags & TF_SIGNATURE) == 0) && 564 (!sack_rxmit || V_tcp_sack_tso) && 565 (ipoptlen == 0 || (ipoptlen == ipsec_optlen && 566 (tp->t_flags2 & TF2_IPSEC_TSO) != 0)) && 567 !(flags & TH_SYN)) 568 tso = 1; 569 570 if (SEQ_LT((sack_rxmit ? p->rxmit : tp->snd_nxt) + len, 571 tp->snd_una + sbused(&so->so_snd))) { 572 flags &= ~TH_FIN; 573 } 574 575 recwin = lmin(lmax(sbspace(&so->so_rcv), 0), 576 (long)TCP_MAXWIN << tp->rcv_scale); 577 578 /* 579 * Sender silly window avoidance. We transmit under the following 580 * conditions when len is non-zero: 581 * 582 * - We have a full segment (or more with TSO) 583 * - This is the last buffer in a write()/send() and we are 584 * either idle or running NODELAY 585 * - we've timed out (e.g. persist timer) 586 * - we have more then 1/2 the maximum send window's worth of 587 * data (receiver may be limited the window size) 588 * - we need to retransmit 589 */ 590 if (len) { 591 if (len >= tp->t_maxseg) 592 goto send; 593 /* 594 * As the TCP header options are now 595 * considered when setting up the initial 596 * window, we would not send the last segment 597 * if we skip considering the option length here. 598 * Note: this may not work when tcp headers change 599 * very dynamically in the future. 600 */ 601 if ((((tp->t_flags & TF_SIGNATURE) ? 602 PADTCPOLEN(TCPOLEN_SIGNATURE) : 0) + 603 ((tp->t_flags & TF_RCVD_TSTMP) ? 604 PADTCPOLEN(TCPOLEN_TIMESTAMP) : 0) + 605 len) >= tp->t_maxseg) 606 goto send; 607 /* 608 * NOTE! on localhost connections an 'ack' from the remote 609 * end may occur synchronously with the output and cause 610 * us to flush a buffer queued with moretocome. XXX 611 * 612 * note: the len + off check is almost certainly unnecessary. 613 */ 614 if (!(tp->t_flags & TF_MORETOCOME) && /* normal case */ 615 (idle || (tp->t_flags & TF_NODELAY)) && 616 (uint32_t)len + (uint32_t)off >= sbavail(&so->so_snd) && 617 (tp->t_flags & TF_NOPUSH) == 0) { 618 goto send; 619 } 620 if (tp->t_flags & TF_FORCEDATA) /* typ. timeout case */ 621 goto send; 622 if (len >= tp->max_sndwnd / 2 && tp->max_sndwnd > 0) 623 goto send; 624 if (SEQ_LT(tp->snd_nxt, tp->snd_max)) /* retransmit case */ 625 goto send; 626 if (sack_rxmit) 627 goto send; 628 } 629 630 /* 631 * Sending of standalone window updates. 632 * 633 * Window updates are important when we close our window due to a 634 * full socket buffer and are opening it again after the application 635 * reads data from it. Once the window has opened again and the 636 * remote end starts to send again the ACK clock takes over and 637 * provides the most current window information. 638 * 639 * We must avoid the silly window syndrome whereas every read 640 * from the receive buffer, no matter how small, causes a window 641 * update to be sent. We also should avoid sending a flurry of 642 * window updates when the socket buffer had queued a lot of data 643 * and the application is doing small reads. 644 * 645 * Prevent a flurry of pointless window updates by only sending 646 * an update when we can increase the advertized window by more 647 * than 1/4th of the socket buffer capacity. When the buffer is 648 * getting full or is very small be more aggressive and send an 649 * update whenever we can increase by two mss sized segments. 650 * In all other situations the ACK's to new incoming data will 651 * carry further window increases. 652 * 653 * Don't send an independent window update if a delayed 654 * ACK is pending (it will get piggy-backed on it) or the 655 * remote side already has done a half-close and won't send 656 * more data. 657 */ 658 if (recwin > 0 && !(tp->t_flags & TF_NEEDSYN) && 659 !(tp->t_flags & TF_DELACK) && 660 !TCPS_HAVERCVDFIN(tp->t_state)) { 661 /* 662 * "adv" is the amount we could increase the window, 663 * taking into account that we are limited by 664 * TCP_MAXWIN << tp->rcv_scale. 665 */ 666 int32_t adv; 667 int oldwin; 668 669 adv = recwin; 670 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt)) { 671 oldwin = (tp->rcv_adv - tp->rcv_nxt); 672 if (adv > oldwin) 673 adv -= oldwin; 674 else 675 adv = 0; 676 } else 677 oldwin = 0; 678 679 /* 680 * If the new window size ends up being the same as or less 681 * than the old size when it is scaled, then don't force 682 * a window update. 683 */ 684 if (oldwin >> tp->rcv_scale >= (adv + oldwin) >> tp->rcv_scale) 685 goto dontupdate; 686 687 if (adv >= (int32_t)(2 * tp->t_maxseg) && 688 (adv >= (int32_t)(so->so_rcv.sb_hiwat / 4) || 689 recwin <= (so->so_rcv.sb_hiwat / 8) || 690 so->so_rcv.sb_hiwat <= 8 * tp->t_maxseg || 691 adv >= TCP_MAXWIN << tp->rcv_scale)) 692 goto send; 693 if (2 * adv >= (int32_t)so->so_rcv.sb_hiwat) 694 goto send; 695 } 696 dontupdate: 697 698 /* 699 * Send if we owe the peer an ACK, RST, SYN, or urgent data. ACKNOW 700 * is also a catch-all for the retransmit timer timeout case. 701 */ 702 if (tp->t_flags & TF_ACKNOW) 703 goto send; 704 if ((flags & TH_RST) || 705 ((flags & TH_SYN) && (tp->t_flags & TF_NEEDSYN) == 0)) 706 goto send; 707 if (SEQ_GT(tp->snd_up, tp->snd_una)) 708 goto send; 709 /* 710 * If our state indicates that FIN should be sent 711 * and we have not yet done so, then we need to send. 712 */ 713 if (flags & TH_FIN && 714 ((tp->t_flags & TF_SENTFIN) == 0 || tp->snd_nxt == tp->snd_una)) 715 goto send; 716 /* 717 * In SACK, it is possible for tcp_output to fail to send a segment 718 * after the retransmission timer has been turned off. Make sure 719 * that the retransmission timer is set. 720 */ 721 if ((tp->t_flags & TF_SACK_PERMIT) && 722 SEQ_GT(tp->snd_max, tp->snd_una) && 723 !tcp_timer_active(tp, TT_REXMT) && 724 !tcp_timer_active(tp, TT_PERSIST)) { 725 tcp_timer_activate(tp, TT_REXMT, TP_RXTCUR(tp)); 726 goto just_return; 727 } 728 /* 729 * TCP window updates are not reliable, rather a polling protocol 730 * using ``persist'' packets is used to insure receipt of window 731 * updates. The three ``states'' for the output side are: 732 * idle not doing retransmits or persists 733 * persisting to move a small or zero window 734 * (re)transmitting and thereby not persisting 735 * 736 * tcp_timer_active(tp, TT_PERSIST) 737 * is true when we are in persist state. 738 * (tp->t_flags & TF_FORCEDATA) 739 * is set when we are called to send a persist packet. 740 * tcp_timer_active(tp, TT_REXMT) 741 * is set when we are retransmitting 742 * The output side is idle when both timers are zero. 743 * 744 * If send window is too small, there is data to transmit, and no 745 * retransmit or persist is pending, then go to persist state. 746 * If nothing happens soon, send when timer expires: 747 * if window is nonzero, transmit what we can, 748 * otherwise force out a byte. 749 */ 750 if (sbavail(&so->so_snd) && !tcp_timer_active(tp, TT_REXMT) && 751 !tcp_timer_active(tp, TT_PERSIST)) { 752 tp->t_rxtshift = 0; 753 tcp_setpersist(tp); 754 } 755 756 /* 757 * No reason to send a segment, just return. 758 */ 759 just_return: 760 SOCK_SENDBUF_UNLOCK(so); 761 return (0); 762 763 send: 764 SOCK_SENDBUF_LOCK_ASSERT(so); 765 if (len > 0) { 766 if (len >= tp->t_maxseg) 767 tp->t_flags2 |= TF2_PLPMTU_MAXSEGSNT; 768 else 769 tp->t_flags2 &= ~TF2_PLPMTU_MAXSEGSNT; 770 } 771 /* 772 * Before ESTABLISHED, force sending of initial options 773 * unless TCP set not to do any options. 774 * NOTE: we assume that the IP/TCP header plus TCP options 775 * always fit in a single mbuf, leaving room for a maximum 776 * link header, i.e. 777 * max_linkhdr + sizeof (struct tcpiphdr) + optlen <= MCLBYTES 778 */ 779 optlen = 0; 780 #ifdef INET6 781 if (isipv6) 782 hdrlen = sizeof (struct ip6_hdr) + sizeof (struct tcphdr); 783 else 784 #endif 785 hdrlen = sizeof (struct tcpiphdr); 786 787 if (flags & TH_SYN) { 788 tp->snd_nxt = tp->iss; 789 } 790 791 /* 792 * Compute options for segment. 793 * We only have to care about SYN and established connection 794 * segments. Options for SYN-ACK segments are handled in TCP 795 * syncache. 796 */ 797 to.to_flags = 0; 798 if ((tp->t_flags & TF_NOOPT) == 0) { 799 /* Maximum segment size. */ 800 if (flags & TH_SYN) { 801 to.to_mss = tcp_mssopt(&inp->inp_inc); 802 if (tp->t_port) 803 to.to_mss -= V_tcp_udp_tunneling_overhead; 804 to.to_flags |= TOF_MSS; 805 806 /* 807 * On SYN or SYN|ACK transmits on TFO connections, 808 * only include the TFO option if it is not a 809 * retransmit, as the presence of the TFO option may 810 * have caused the original SYN or SYN|ACK to have 811 * been dropped by a middlebox. 812 */ 813 if ((tp->t_flags & TF_FASTOPEN) && 814 (tp->t_rxtshift == 0)) { 815 if (tp->t_state == TCPS_SYN_RECEIVED) { 816 to.to_tfo_len = TCP_FASTOPEN_COOKIE_LEN; 817 to.to_tfo_cookie = 818 (u_int8_t *)&tp->t_tfo_cookie.server; 819 to.to_flags |= TOF_FASTOPEN; 820 wanted_cookie = 1; 821 } else if (tp->t_state == TCPS_SYN_SENT) { 822 to.to_tfo_len = 823 tp->t_tfo_client_cookie_len; 824 to.to_tfo_cookie = 825 tp->t_tfo_cookie.client; 826 to.to_flags |= TOF_FASTOPEN; 827 wanted_cookie = 1; 828 /* 829 * If we wind up having more data to 830 * send with the SYN than can fit in 831 * one segment, don't send any more 832 * until the SYN|ACK comes back from 833 * the other end. 834 */ 835 dont_sendalot = 1; 836 } 837 } 838 } 839 /* Window scaling. */ 840 if ((flags & TH_SYN) && (tp->t_flags & TF_REQ_SCALE)) { 841 to.to_wscale = tp->request_r_scale; 842 to.to_flags |= TOF_SCALE; 843 } 844 /* Timestamps. */ 845 if ((tp->t_flags & TF_RCVD_TSTMP) || 846 ((flags & TH_SYN) && (tp->t_flags & TF_REQ_TSTMP))) { 847 curticks = tcp_ts_getticks(); 848 to.to_tsval = curticks + tp->ts_offset; 849 to.to_tsecr = tp->ts_recent; 850 to.to_flags |= TOF_TS; 851 if (tp->t_rxtshift == 1) 852 tp->t_badrxtwin = curticks; 853 } 854 855 /* Set receive buffer autosizing timestamp. */ 856 if (tp->rfbuf_ts == 0 && 857 (so->so_rcv.sb_flags & SB_AUTOSIZE)) 858 tp->rfbuf_ts = tcp_ts_getticks(); 859 860 /* Selective ACK's. */ 861 if (tp->t_flags & TF_SACK_PERMIT) { 862 if (flags & TH_SYN) 863 to.to_flags |= TOF_SACKPERM; 864 else if (TCPS_HAVEESTABLISHED(tp->t_state) && 865 tp->rcv_numsacks > 0) { 866 to.to_flags |= TOF_SACK; 867 to.to_nsacks = tp->rcv_numsacks; 868 to.to_sacks = (u_char *)tp->sackblks; 869 } 870 } 871 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 872 /* TCP-MD5 (RFC2385). */ 873 /* 874 * Check that TCP_MD5SIG is enabled in tcpcb to 875 * account the size needed to set this TCP option. 876 */ 877 if (tp->t_flags & TF_SIGNATURE) 878 to.to_flags |= TOF_SIGNATURE; 879 #endif /* TCP_SIGNATURE */ 880 881 /* Processing the options. */ 882 hdrlen += optlen = tcp_addoptions(&to, opt); 883 /* 884 * If we wanted a TFO option to be added, but it was unable 885 * to fit, ensure no data is sent. 886 */ 887 if ((tp->t_flags & TF_FASTOPEN) && wanted_cookie && 888 !(to.to_flags & TOF_FASTOPEN)) 889 len = 0; 890 } 891 if (tp->t_port) { 892 if (V_tcp_udp_tunneling_port == 0) { 893 /* The port was removed?? */ 894 SOCK_SENDBUF_UNLOCK(so); 895 return (EHOSTUNREACH); 896 } 897 hdrlen += sizeof(struct udphdr); 898 } 899 /* 900 * Adjust data length if insertion of options will 901 * bump the packet length beyond the t_maxseg length. 902 * Clear the FIN bit because we cut off the tail of 903 * the segment. 904 */ 905 if (len + optlen + ipoptlen > tp->t_maxseg) { 906 flags &= ~TH_FIN; 907 908 if (tso) { 909 u_int if_hw_tsomax; 910 u_int moff; 911 int max_len; 912 913 /* extract TSO information */ 914 if_hw_tsomax = tp->t_tsomax; 915 if_hw_tsomaxsegcount = tp->t_tsomaxsegcount; 916 if_hw_tsomaxsegsize = tp->t_tsomaxsegsize; 917 918 /* 919 * Limit a TSO burst to prevent it from 920 * overflowing or exceeding the maximum length 921 * allowed by the network interface: 922 */ 923 KASSERT(ipoptlen == ipsec_optlen, 924 ("%s: TSO can't do IP options", __func__)); 925 926 /* 927 * Check if we should limit by maximum payload 928 * length: 929 */ 930 if (if_hw_tsomax != 0) { 931 /* compute maximum TSO length */ 932 max_len = if_hw_tsomax - hdrlen - 933 ipsec_optlen - max_linkhdr; 934 if (max_len <= 0) { 935 len = 0; 936 } else if (len > max_len) { 937 sendalot = 1; 938 len = max_len; 939 } 940 } 941 942 /* 943 * Prevent the last segment from being 944 * fractional unless the send sockbuf can be 945 * emptied: 946 */ 947 max_len = tp->t_maxseg - optlen - ipsec_optlen; 948 if (((uint32_t)off + (uint32_t)len) < 949 sbavail(&so->so_snd)) { 950 moff = len % max_len; 951 if (moff != 0) { 952 len -= moff; 953 sendalot = 1; 954 } 955 } 956 957 /* 958 * In case there are too many small fragments 959 * don't use TSO: 960 */ 961 if (len <= max_len) { 962 len = max_len; 963 sendalot = 1; 964 tso = 0; 965 } 966 967 /* 968 * Send the FIN in a separate segment 969 * after the bulk sending is done. 970 * We don't trust the TSO implementations 971 * to clear the FIN flag on all but the 972 * last segment. 973 */ 974 if (tp->t_flags & TF_NEEDFIN) 975 sendalot = 1; 976 } else { 977 if (optlen + ipoptlen >= tp->t_maxseg) { 978 /* 979 * Since we don't have enough space to put 980 * the IP header chain and the TCP header in 981 * one packet as required by RFC 7112, don't 982 * send it. Also ensure that at least one 983 * byte of the payload can be put into the 984 * TCP segment. 985 */ 986 SOCK_SENDBUF_UNLOCK(so); 987 error = EMSGSIZE; 988 sack_rxmit = false; 989 goto out; 990 } 991 len = tp->t_maxseg - optlen - ipoptlen; 992 sendalot = 1; 993 if (dont_sendalot) 994 sendalot = 0; 995 } 996 } else 997 tso = 0; 998 999 KASSERT(len + hdrlen + ipoptlen <= IP_MAXPACKET, 1000 ("%s: len > IP_MAXPACKET", __func__)); 1001 1002 /*#ifdef DIAGNOSTIC*/ 1003 #ifdef INET6 1004 if (max_linkhdr + hdrlen > MCLBYTES) 1005 #else 1006 if (max_linkhdr + hdrlen > MHLEN) 1007 #endif 1008 panic("tcphdr too big"); 1009 /*#endif*/ 1010 1011 /* 1012 * This KASSERT is here to catch edge cases at a well defined place. 1013 * Before, those had triggered (random) panic conditions further down. 1014 */ 1015 KASSERT(len >= 0, ("[%s:%d]: len < 0", __func__, __LINE__)); 1016 1017 /* 1018 * Grab a header mbuf, attaching a copy of data to 1019 * be transmitted, and initialize the header from 1020 * the template for sends on this connection. 1021 */ 1022 if (len) { 1023 struct mbuf *mb; 1024 struct sockbuf *msb; 1025 u_int moff; 1026 1027 if ((tp->t_flags & TF_FORCEDATA) && len == 1) { 1028 TCPSTAT_INC(tcps_sndprobe); 1029 #ifdef STATS 1030 if (SEQ_LT(tp->snd_nxt, tp->snd_max)) 1031 stats_voi_update_abs_u32(tp->t_stats, 1032 VOI_TCP_RETXPB, len); 1033 else 1034 stats_voi_update_abs_u64(tp->t_stats, 1035 VOI_TCP_TXPB, len); 1036 #endif /* STATS */ 1037 } else if (SEQ_LT(tp->snd_nxt, tp->snd_max) || sack_rxmit) { 1038 tp->t_sndrexmitpack++; 1039 TCPSTAT_INC(tcps_sndrexmitpack); 1040 TCPSTAT_ADD(tcps_sndrexmitbyte, len); 1041 if (sack_rxmit) { 1042 TCPSTAT_INC(tcps_sack_rexmits); 1043 if (tso) { 1044 TCPSTAT_INC(tcps_sack_rexmits_tso); 1045 } 1046 TCPSTAT_ADD(tcps_sack_rexmit_bytes, len); 1047 } 1048 #ifdef STATS 1049 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_RETXPB, 1050 len); 1051 #endif /* STATS */ 1052 } else { 1053 TCPSTAT_INC(tcps_sndpack); 1054 TCPSTAT_ADD(tcps_sndbyte, len); 1055 #ifdef STATS 1056 stats_voi_update_abs_u64(tp->t_stats, VOI_TCP_TXPB, 1057 len); 1058 #endif /* STATS */ 1059 } 1060 #ifdef INET6 1061 if (MHLEN < hdrlen + max_linkhdr) 1062 m = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR); 1063 else 1064 #endif 1065 m = m_gethdr(M_NOWAIT, MT_DATA); 1066 1067 if (m == NULL) { 1068 SOCK_SENDBUF_UNLOCK(so); 1069 error = ENOBUFS; 1070 sack_rxmit = false; 1071 goto out; 1072 } 1073 1074 m->m_data += max_linkhdr; 1075 m->m_len = hdrlen; 1076 1077 /* 1078 * Start the m_copy functions from the closest mbuf 1079 * to the offset in the socket buffer chain. 1080 */ 1081 mb = sbsndptr_noadv(&so->so_snd, off, &moff); 1082 if (len <= MHLEN - hdrlen - max_linkhdr && !hw_tls) { 1083 m_copydata(mb, moff, len, 1084 mtod(m, caddr_t) + hdrlen); 1085 if (SEQ_LT(tp->snd_nxt, tp->snd_max)) 1086 sbsndptr_adv(&so->so_snd, mb, len); 1087 m->m_len += len; 1088 } else { 1089 int32_t old_len; 1090 1091 if (SEQ_LT(tp->snd_nxt, tp->snd_max)) 1092 msb = NULL; 1093 else 1094 msb = &so->so_snd; 1095 old_len = len; 1096 m->m_next = tcp_m_copym(mb, moff, 1097 &len, if_hw_tsomaxsegcount, 1098 if_hw_tsomaxsegsize, msb, hw_tls); 1099 if (old_len != len) 1100 flags &= ~TH_FIN; 1101 if (len <= (tp->t_maxseg - optlen)) { 1102 /* 1103 * Must have ran out of mbufs for the copy 1104 * shorten it to no longer need tso. Lets 1105 * not put on sendalot since we are low on 1106 * mbufs. 1107 */ 1108 tso = 0; 1109 } 1110 if (m->m_next == NULL) { 1111 SOCK_SENDBUF_UNLOCK(so); 1112 (void) m_free(m); 1113 error = ENOBUFS; 1114 sack_rxmit = false; 1115 goto out; 1116 } 1117 } 1118 1119 /* 1120 * If we're sending everything we've got, set PUSH. 1121 * (This will keep happy those implementations which only 1122 * give data to the user when a buffer fills or 1123 * a PUSH comes in.) 1124 */ 1125 if (((uint32_t)off + (uint32_t)len == sbused(&so->so_snd)) && 1126 !(flags & TH_SYN)) 1127 flags |= TH_PUSH; 1128 SOCK_SENDBUF_UNLOCK(so); 1129 } else { 1130 SOCK_SENDBUF_UNLOCK(so); 1131 if (tp->t_flags & TF_ACKNOW) 1132 TCPSTAT_INC(tcps_sndacks); 1133 else if (flags & (TH_SYN|TH_FIN|TH_RST)) 1134 TCPSTAT_INC(tcps_sndctrl); 1135 else if (SEQ_GT(tp->snd_up, tp->snd_una)) 1136 TCPSTAT_INC(tcps_sndurg); 1137 else 1138 TCPSTAT_INC(tcps_sndwinup); 1139 1140 m = m_gethdr(M_NOWAIT, MT_DATA); 1141 if (m == NULL) { 1142 error = ENOBUFS; 1143 sack_rxmit = false; 1144 goto out; 1145 } 1146 #ifdef INET6 1147 if (isipv6 && (MHLEN < hdrlen + max_linkhdr) && 1148 MHLEN >= hdrlen) { 1149 M_ALIGN(m, hdrlen); 1150 } else 1151 #endif 1152 m->m_data += max_linkhdr; 1153 m->m_len = hdrlen; 1154 } 1155 SOCK_SENDBUF_UNLOCK_ASSERT(so); 1156 m->m_pkthdr.rcvif = (struct ifnet *)0; 1157 #ifdef MAC 1158 mac_inpcb_create_mbuf(inp, m); 1159 #endif 1160 #ifdef INET6 1161 if (isipv6) { 1162 ip6 = mtod(m, struct ip6_hdr *); 1163 if (tp->t_port) { 1164 udp = (struct udphdr *)((caddr_t)ip6 + sizeof(struct ip6_hdr)); 1165 udp->uh_sport = htons(V_tcp_udp_tunneling_port); 1166 udp->uh_dport = tp->t_port; 1167 ulen = hdrlen + len - sizeof(struct ip6_hdr); 1168 udp->uh_ulen = htons(ulen); 1169 th = (struct tcphdr *)(udp + 1); 1170 } else { 1171 th = (struct tcphdr *)(ip6 + 1); 1172 } 1173 tcpip_fillheaders(inp, tp->t_port, ip6, th); 1174 } else 1175 #endif /* INET6 */ 1176 { 1177 ip = mtod(m, struct ip *); 1178 if (tp->t_port) { 1179 udp = (struct udphdr *)((caddr_t)ip + sizeof(struct ip)); 1180 udp->uh_sport = htons(V_tcp_udp_tunneling_port); 1181 udp->uh_dport = tp->t_port; 1182 ulen = hdrlen + len - sizeof(struct ip); 1183 udp->uh_ulen = htons(ulen); 1184 th = (struct tcphdr *)(udp + 1); 1185 } else 1186 th = (struct tcphdr *)(ip + 1); 1187 tcpip_fillheaders(inp, tp->t_port, ip, th); 1188 } 1189 1190 /* 1191 * Fill in fields, remembering maximum advertised 1192 * window for use in delaying messages about window sizes. 1193 * If resending a FIN, be sure not to use a new sequence number. 1194 */ 1195 if (flags & TH_FIN && tp->t_flags & TF_SENTFIN && 1196 tp->snd_nxt == tp->snd_max) 1197 tp->snd_nxt--; 1198 /* 1199 * If we are starting a connection, send ECN setup 1200 * SYN packet. If we are on a retransmit, we may 1201 * resend those bits a number of times as per 1202 * RFC 3168. 1203 */ 1204 if (tp->t_state == TCPS_SYN_SENT && V_tcp_do_ecn) { 1205 flags |= tcp_ecn_output_syn_sent(tp); 1206 } 1207 /* Also handle parallel SYN for ECN */ 1208 if ((TCPS_HAVERCVDSYN(tp->t_state)) && 1209 (tp->t_flags2 & (TF2_ECN_PERMIT | TF2_ACE_PERMIT))) { 1210 int ect = tcp_ecn_output_established(tp, &flags, len, sack_rxmit); 1211 if ((tp->t_state == TCPS_SYN_RECEIVED) && 1212 (tp->t_flags2 & TF2_ECN_SND_ECE)) 1213 tp->t_flags2 &= ~TF2_ECN_SND_ECE; 1214 #ifdef INET6 1215 if (isipv6) { 1216 ip6->ip6_flow &= ~htonl(IPTOS_ECN_MASK << IPV6_FLOWLABEL_LEN); 1217 ip6->ip6_flow |= htonl(ect << IPV6_FLOWLABEL_LEN); 1218 } 1219 else 1220 #endif 1221 { 1222 ip->ip_tos &= ~IPTOS_ECN_MASK; 1223 ip->ip_tos |= ect; 1224 } 1225 } 1226 1227 /* 1228 * If we are doing retransmissions, then snd_nxt will 1229 * not reflect the first unsent octet. For ACK only 1230 * packets, we do not want the sequence number of the 1231 * retransmitted packet, we want the sequence number 1232 * of the next unsent octet. So, if there is no data 1233 * (and no SYN or FIN), use snd_max instead of snd_nxt 1234 * when filling in ti_seq. But if we are in persist 1235 * state, snd_max might reflect one byte beyond the 1236 * right edge of the window, so use snd_nxt in that 1237 * case, since we know we aren't doing a retransmission. 1238 * (retransmit and persist are mutually exclusive...) 1239 */ 1240 if (!sack_rxmit) { 1241 if (len || (flags & (TH_SYN|TH_FIN)) || 1242 tcp_timer_active(tp, TT_PERSIST)) 1243 th->th_seq = htonl(tp->snd_nxt); 1244 else 1245 th->th_seq = htonl(tp->snd_max); 1246 } else { 1247 th->th_seq = htonl(p->rxmit); 1248 p->rxmit += len; 1249 /* 1250 * Lost Retransmission Detection 1251 * trigger resending of a (then 1252 * still existing) hole, when 1253 * fack acks recoverypoint. 1254 */ 1255 if ((tp->t_flags & TF_LRD) && SEQ_GEQ(p->rxmit, p->end)) 1256 p->rxmit = tp->snd_recover; 1257 tp->sackhint.sack_bytes_rexmit += len; 1258 } 1259 if (IN_RECOVERY(tp->t_flags)) { 1260 /* 1261 * Account all bytes transmitted while 1262 * IN_RECOVERY, simplifying PRR and 1263 * Lost Retransmit Detection 1264 */ 1265 tp->sackhint.prr_out += len; 1266 } 1267 th->th_ack = htonl(tp->rcv_nxt); 1268 if (optlen) { 1269 bcopy(opt, th + 1, optlen); 1270 th->th_off = (sizeof (struct tcphdr) + optlen) >> 2; 1271 } 1272 /* 1273 * Calculate receive window. Don't shrink window, 1274 * but avoid silly window syndrome. 1275 * If a RST segment is sent, advertise a window of zero. 1276 */ 1277 if (flags & TH_RST) { 1278 recwin = 0; 1279 } else { 1280 if (recwin < (so->so_rcv.sb_hiwat / 4) && 1281 recwin < tp->t_maxseg) 1282 recwin = 0; 1283 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt) && 1284 recwin < (tp->rcv_adv - tp->rcv_nxt)) 1285 recwin = (tp->rcv_adv - tp->rcv_nxt); 1286 } 1287 /* 1288 * According to RFC1323 the window field in a SYN (i.e., a <SYN> 1289 * or <SYN,ACK>) segment itself is never scaled. The <SYN,ACK> 1290 * case is handled in syncache. 1291 */ 1292 if (flags & TH_SYN) 1293 th->th_win = htons((u_short) 1294 (min(sbspace(&so->so_rcv), TCP_MAXWIN))); 1295 else { 1296 /* Avoid shrinking window with window scaling. */ 1297 recwin = roundup2(recwin, 1 << tp->rcv_scale); 1298 th->th_win = htons((u_short)(recwin >> tp->rcv_scale)); 1299 } 1300 1301 /* 1302 * Adjust the RXWIN0SENT flag - indicate that we have advertised 1303 * a 0 window. This may cause the remote transmitter to stall. This 1304 * flag tells soreceive() to disable delayed acknowledgements when 1305 * draining the buffer. This can occur if the receiver is attempting 1306 * to read more data than can be buffered prior to transmitting on 1307 * the connection. 1308 */ 1309 if (th->th_win == 0) { 1310 tp->t_sndzerowin++; 1311 tp->t_flags |= TF_RXWIN0SENT; 1312 } else 1313 tp->t_flags &= ~TF_RXWIN0SENT; 1314 if (SEQ_GT(tp->snd_up, tp->snd_nxt)) { 1315 th->th_urp = htons((u_short)(tp->snd_up - tp->snd_nxt)); 1316 flags |= TH_URG; 1317 } else { 1318 /* 1319 * If no urgent pointer to send, then we pull 1320 * the urgent pointer to the left edge of the send window 1321 * so that it doesn't drift into the send window on sequence 1322 * number wraparound. 1323 */ 1324 tp->snd_up = tp->snd_una; /* drag it along */ 1325 } 1326 tcp_set_flags(th, flags); 1327 1328 /* 1329 * Put TCP length in extended header, and then 1330 * checksum extended header and data. 1331 */ 1332 m->m_pkthdr.len = hdrlen + len; /* in6_cksum() need this */ 1333 1334 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 1335 if (to.to_flags & TOF_SIGNATURE) { 1336 /* 1337 * Calculate MD5 signature and put it into the place 1338 * determined before. 1339 * NOTE: since TCP options buffer doesn't point into 1340 * mbuf's data, calculate offset and use it. 1341 */ 1342 if (!TCPMD5_ENABLED() || (error = TCPMD5_OUTPUT(m, th, 1343 (u_char *)(th + 1) + (to.to_signature - opt))) != 0) { 1344 /* 1345 * Do not send segment if the calculation of MD5 1346 * digest has failed. 1347 */ 1348 m_freem(m); 1349 goto out; 1350 } 1351 } 1352 #endif 1353 #ifdef INET6 1354 if (isipv6) { 1355 /* 1356 * There is no need to fill in ip6_plen right now. 1357 * It will be filled later by ip6_output. 1358 */ 1359 if (tp->t_port) { 1360 m->m_pkthdr.csum_flags = CSUM_UDP_IPV6; 1361 m->m_pkthdr.csum_data = offsetof(struct udphdr, uh_sum); 1362 udp->uh_sum = in6_cksum_pseudo(ip6, ulen, IPPROTO_UDP, 0); 1363 th->th_sum = htons(0); 1364 UDPSTAT_INC(udps_opackets); 1365 } else { 1366 m->m_pkthdr.csum_flags = CSUM_TCP_IPV6; 1367 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 1368 th->th_sum = in6_cksum_pseudo(ip6, 1369 sizeof(struct tcphdr) + optlen + len, IPPROTO_TCP, 1370 0); 1371 } 1372 } 1373 #endif 1374 #if defined(INET6) && defined(INET) 1375 else 1376 #endif 1377 #ifdef INET 1378 { 1379 if (tp->t_port) { 1380 m->m_pkthdr.csum_flags = CSUM_UDP; 1381 m->m_pkthdr.csum_data = offsetof(struct udphdr, uh_sum); 1382 udp->uh_sum = in_pseudo(ip->ip_src.s_addr, 1383 ip->ip_dst.s_addr, htons(ulen + IPPROTO_UDP)); 1384 th->th_sum = htons(0); 1385 UDPSTAT_INC(udps_opackets); 1386 } else { 1387 m->m_pkthdr.csum_flags = CSUM_TCP; 1388 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum); 1389 th->th_sum = in_pseudo(ip->ip_src.s_addr, 1390 ip->ip_dst.s_addr, htons(sizeof(struct tcphdr) + 1391 IPPROTO_TCP + len + optlen)); 1392 } 1393 1394 /* IP version must be set here for ipv4/ipv6 checking later */ 1395 KASSERT(ip->ip_v == IPVERSION, 1396 ("%s: IP version incorrect: %d", __func__, ip->ip_v)); 1397 } 1398 #endif 1399 1400 /* 1401 * Enable TSO and specify the size of the segments. 1402 * The TCP pseudo header checksum is always provided. 1403 */ 1404 if (tso) { 1405 KASSERT(len > tp->t_maxseg - optlen - ipsec_optlen, 1406 ("%s: len <= tso_segsz", __func__)); 1407 m->m_pkthdr.csum_flags |= CSUM_TSO; 1408 m->m_pkthdr.tso_segsz = tp->t_maxseg - optlen - ipsec_optlen; 1409 } 1410 1411 KASSERT(len + hdrlen == m_length(m, NULL), 1412 ("%s: mbuf chain shorter than expected: %d + %u != %u", 1413 __func__, len, hdrlen, m_length(m, NULL))); 1414 1415 #ifdef TCP_HHOOK 1416 /* Run HHOOK_TCP_ESTABLISHED_OUT helper hooks. */ 1417 hhook_run_tcp_est_out(tp, th, &to, len, tso); 1418 #endif 1419 1420 TCP_PROBE3(debug__output, tp, th, m); 1421 1422 /* We're getting ready to send; log now. */ 1423 /* XXXMT: We are not honoring verbose logging. */ 1424 1425 if (tcp_bblogging_on(tp)) 1426 lgb = tcp_log_event(tp, th, &so->so_rcv, &so->so_snd, 1427 TCP_LOG_OUT, ERRNO_UNK, len, NULL, false, NULL, NULL, 0, 1428 NULL); 1429 else 1430 lgb = NULL; 1431 1432 /* 1433 * Fill in IP length and desired time to live and 1434 * send to IP level. There should be a better way 1435 * to handle ttl and tos; we could keep them in 1436 * the template, but need a way to checksum without them. 1437 */ 1438 /* 1439 * m->m_pkthdr.len should have been set before checksum calculation, 1440 * because in6_cksum() need it. 1441 */ 1442 #ifdef INET6 1443 if (isipv6) { 1444 /* 1445 * we separately set hoplimit for every segment, since the 1446 * user might want to change the value via setsockopt. 1447 * Also, desired default hop limit might be changed via 1448 * Neighbor Discovery. 1449 */ 1450 ip6->ip6_hlim = in6_selecthlim(inp, NULL); 1451 1452 /* 1453 * Set the packet size here for the benefit of DTrace probes. 1454 * ip6_output() will set it properly; it's supposed to include 1455 * the option header lengths as well. 1456 */ 1457 ip6->ip6_plen = htons(m->m_pkthdr.len - sizeof(*ip6)); 1458 1459 if (V_path_mtu_discovery && tp->t_maxseg > V_tcp_minmss) 1460 tp->t_flags2 |= TF2_PLPMTU_PMTUD; 1461 else 1462 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD; 1463 1464 if (tp->t_state == TCPS_SYN_SENT) 1465 TCP_PROBE5(connect__request, NULL, tp, ip6, tp, th); 1466 1467 TCP_PROBE5(send, NULL, tp, ip6, tp, th); 1468 1469 #ifdef TCPPCAP 1470 /* Save packet, if requested. */ 1471 tcp_pcap_add(th, m, &(tp->t_outpkts)); 1472 #endif 1473 1474 /* TODO: IPv6 IP6TOS_ECT bit on */ 1475 error = ip6_output(m, inp->in6p_outputopts, &inp->inp_route6, 1476 ((so->so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0), 1477 NULL, NULL, inp); 1478 1479 if (error == EMSGSIZE && inp->inp_route6.ro_nh != NULL) 1480 mtu = inp->inp_route6.ro_nh->nh_mtu; 1481 } 1482 #endif /* INET6 */ 1483 #if defined(INET) && defined(INET6) 1484 else 1485 #endif 1486 #ifdef INET 1487 { 1488 ip->ip_len = htons(m->m_pkthdr.len); 1489 #ifdef INET6 1490 if (inp->inp_vflag & INP_IPV6PROTO) 1491 ip->ip_ttl = in6_selecthlim(inp, NULL); 1492 #endif /* INET6 */ 1493 /* 1494 * If we do path MTU discovery, then we set DF on every packet. 1495 * This might not be the best thing to do according to RFC3390 1496 * Section 2. However the tcp hostcache migitates the problem 1497 * so it affects only the first tcp connection with a host. 1498 * 1499 * NB: Don't set DF on small MTU/MSS to have a safe fallback. 1500 */ 1501 if (V_path_mtu_discovery && tp->t_maxseg > V_tcp_minmss) { 1502 tp->t_flags2 |= TF2_PLPMTU_PMTUD; 1503 if (tp->t_port == 0 || len < V_tcp_minmss) { 1504 ip->ip_off |= htons(IP_DF); 1505 } 1506 } else { 1507 tp->t_flags2 &= ~TF2_PLPMTU_PMTUD; 1508 } 1509 1510 if (tp->t_state == TCPS_SYN_SENT) 1511 TCP_PROBE5(connect__request, NULL, tp, ip, tp, th); 1512 1513 TCP_PROBE5(send, NULL, tp, ip, tp, th); 1514 1515 #ifdef TCPPCAP 1516 /* Save packet, if requested. */ 1517 tcp_pcap_add(th, m, &(tp->t_outpkts)); 1518 #endif 1519 1520 error = ip_output(m, inp->inp_options, &inp->inp_route, 1521 ((so->so_options & SO_DONTROUTE) ? IP_ROUTETOIF : 0), 0, inp); 1522 1523 if (error == EMSGSIZE && inp->inp_route.ro_nh != NULL) 1524 mtu = inp->inp_route.ro_nh->nh_mtu; 1525 } 1526 #endif /* INET */ 1527 1528 if (lgb != NULL) { 1529 lgb->tlb_errno = error; 1530 lgb = NULL; 1531 } 1532 out: 1533 if (error == 0) 1534 tcp_account_for_send(tp, len, (tp->snd_nxt != tp->snd_max), 0, hw_tls); 1535 /* 1536 * In transmit state, time the transmission and arrange for 1537 * the retransmit. In persist state, just set snd_max. In a closed 1538 * state just return. 1539 */ 1540 if (flags & TH_RST) { 1541 TCPSTAT_INC(tcps_sndtotal); 1542 return (0); 1543 } else if ((tp->t_flags & TF_FORCEDATA) == 0 || 1544 !tcp_timer_active(tp, TT_PERSIST)) { 1545 tcp_seq startseq = tp->snd_nxt; 1546 1547 /* 1548 * Advance snd_nxt over sequence space of this segment. 1549 */ 1550 if (flags & (TH_SYN|TH_FIN)) { 1551 if (flags & TH_SYN) 1552 tp->snd_nxt++; 1553 if (flags & TH_FIN) { 1554 tp->snd_nxt++; 1555 tp->t_flags |= TF_SENTFIN; 1556 } 1557 } 1558 if (sack_rxmit) 1559 goto timer; 1560 tp->snd_nxt += len; 1561 if (SEQ_GT(tp->snd_nxt, tp->snd_max)) { 1562 /* 1563 * Update "made progress" indication if we just 1564 * added new data to an empty socket buffer. 1565 */ 1566 if (tp->snd_una == tp->snd_max) 1567 tp->t_acktime = ticks; 1568 tp->snd_max = tp->snd_nxt; 1569 /* 1570 * Time this transmission if not a retransmission and 1571 * not currently timing anything. 1572 */ 1573 tp->t_sndtime = ticks; 1574 if (tp->t_rtttime == 0) { 1575 tp->t_rtttime = ticks; 1576 tp->t_rtseq = startseq; 1577 TCPSTAT_INC(tcps_segstimed); 1578 } 1579 #ifdef STATS 1580 if (!(tp->t_flags & TF_GPUTINPROG) && len) { 1581 tp->t_flags |= TF_GPUTINPROG; 1582 tp->gput_seq = startseq; 1583 tp->gput_ack = startseq + 1584 ulmin(sbavail(&so->so_snd) - off, sendwin); 1585 tp->gput_ts = tcp_ts_getticks(); 1586 } 1587 #endif /* STATS */ 1588 } 1589 1590 /* 1591 * Set retransmit timer if not currently set, 1592 * and not doing a pure ack or a keep-alive probe. 1593 * Initial value for retransmit timer is smoothed 1594 * round-trip time + 2 * round-trip time variance. 1595 * Initialize shift counter which is used for backoff 1596 * of retransmit time. 1597 */ 1598 timer: 1599 if (!tcp_timer_active(tp, TT_REXMT) && 1600 ((sack_rxmit && tp->snd_nxt != tp->snd_max) || 1601 (tp->snd_nxt != tp->snd_una))) { 1602 if (tcp_timer_active(tp, TT_PERSIST)) { 1603 tcp_timer_activate(tp, TT_PERSIST, 0); 1604 tp->t_rxtshift = 0; 1605 } 1606 tcp_timer_activate(tp, TT_REXMT, TP_RXTCUR(tp)); 1607 } else if (len == 0 && sbavail(&so->so_snd) && 1608 !tcp_timer_active(tp, TT_REXMT) && 1609 !tcp_timer_active(tp, TT_PERSIST)) { 1610 /* 1611 * Avoid a situation where we do not set persist timer 1612 * after a zero window condition. For example: 1613 * 1) A -> B: packet with enough data to fill the window 1614 * 2) B -> A: ACK for #1 + new data (0 window 1615 * advertisement) 1616 * 3) A -> B: ACK for #2, 0 len packet 1617 * 1618 * In this case, A will not activate the persist timer, 1619 * because it chose to send a packet. Unless tcp_output 1620 * is called for some other reason (delayed ack timer, 1621 * another input packet from B, socket syscall), A will 1622 * not send zero window probes. 1623 * 1624 * So, if you send a 0-length packet, but there is data 1625 * in the socket buffer, and neither the rexmt or 1626 * persist timer is already set, then activate the 1627 * persist timer. 1628 */ 1629 tp->t_rxtshift = 0; 1630 tcp_setpersist(tp); 1631 } 1632 } else { 1633 /* 1634 * Persist case, update snd_max but since we are in 1635 * persist mode (no window) we do not update snd_nxt. 1636 */ 1637 int xlen = len; 1638 if (flags & TH_SYN) 1639 ++xlen; 1640 if (flags & TH_FIN) { 1641 ++xlen; 1642 tp->t_flags |= TF_SENTFIN; 1643 } 1644 if (SEQ_GT(tp->snd_nxt + xlen, tp->snd_max)) 1645 tp->snd_max = tp->snd_nxt + xlen; 1646 } 1647 if ((error == 0) && 1648 (tp->rcv_numsacks > 0) && 1649 TCPS_HAVEESTABLISHED(tp->t_state) && 1650 (tp->t_flags & TF_SACK_PERMIT)) { 1651 /* Clean up any DSACK's sent */ 1652 tcp_clean_dsack_blocks(tp); 1653 } 1654 if ((error == 0) && 1655 sack_rxmit && 1656 SEQ_LT(tp->snd_nxt, SEQ_MIN(p->rxmit, p->end))) { 1657 /* 1658 * When transmitting from SACK scoreboard 1659 * after an RTO, pull snd_nxt along. 1660 */ 1661 tp->snd_nxt = SEQ_MIN(p->rxmit, p->end); 1662 } 1663 if (error) { 1664 /* 1665 * We know that the packet was lost, so back out the 1666 * sequence number advance, if any. 1667 * 1668 * If the error is EPERM the packet got blocked by the 1669 * local firewall. Normally we should terminate the 1670 * connection but the blocking may have been spurious 1671 * due to a firewall reconfiguration cycle. So we treat 1672 * it like a packet loss and let the retransmit timer and 1673 * timeouts do their work over time. 1674 * XXX: It is a POLA question whether calling tcp_drop right 1675 * away would be the really correct behavior instead. 1676 */ 1677 if (((tp->t_flags & TF_FORCEDATA) == 0 || 1678 !tcp_timer_active(tp, TT_PERSIST)) && 1679 ((flags & TH_SYN) == 0) && 1680 (error != EPERM)) { 1681 if (sack_rxmit) { 1682 p->rxmit = SEQ_MIN(p->end, p->rxmit) - len; 1683 tp->sackhint.sack_bytes_rexmit -= len; 1684 KASSERT(tp->sackhint.sack_bytes_rexmit >= 0, 1685 ("sackhint bytes rtx >= 0")); 1686 KASSERT((flags & TH_FIN) == 0, 1687 ("error while FIN with SACK rxmit")); 1688 } else { 1689 tp->snd_nxt -= len; 1690 if (flags & TH_FIN) 1691 tp->snd_nxt--; 1692 } 1693 if (IN_RECOVERY(tp->t_flags)) 1694 tp->sackhint.prr_out -= len; 1695 } 1696 SOCK_SENDBUF_UNLOCK_ASSERT(so); /* Check gotos. */ 1697 switch (error) { 1698 case EACCES: 1699 case EPERM: 1700 tp->t_softerror = error; 1701 return (error); 1702 case ENOBUFS: 1703 TCP_XMIT_TIMER_ASSERT(tp, len, flags); 1704 tp->snd_cwnd = tcp_maxseg(tp); 1705 return (0); 1706 case EMSGSIZE: 1707 /* 1708 * For some reason the interface we used initially 1709 * to send segments changed to another or lowered 1710 * its MTU. 1711 * If TSO was active we either got an interface 1712 * without TSO capabilits or TSO was turned off. 1713 * If we obtained mtu from ip_output() then update 1714 * it and try again. 1715 */ 1716 if (tso) 1717 tp->t_flags &= ~TF_TSO; 1718 if (mtu != 0) { 1719 tcp_mss_update(tp, -1, mtu, NULL, NULL); 1720 goto again; 1721 } 1722 return (error); 1723 case EHOSTDOWN: 1724 case EHOSTUNREACH: 1725 case ENETDOWN: 1726 case ENETUNREACH: 1727 if (TCPS_HAVERCVDSYN(tp->t_state)) { 1728 tp->t_softerror = error; 1729 return (0); 1730 } 1731 /* FALLTHROUGH */ 1732 default: 1733 return (error); 1734 } 1735 } 1736 TCPSTAT_INC(tcps_sndtotal); 1737 1738 /* 1739 * Data sent (as far as we can tell). 1740 * If this advertises a larger window than any other segment, 1741 * then remember the size of the advertised window. 1742 * Any pending ACK has now been sent. 1743 */ 1744 if (SEQ_GT(tp->rcv_nxt + recwin, tp->rcv_adv)) 1745 tp->rcv_adv = tp->rcv_nxt + recwin; 1746 tp->last_ack_sent = tp->rcv_nxt; 1747 tp->t_flags &= ~(TF_ACKNOW | TF_DELACK); 1748 if (tcp_timer_active(tp, TT_DELACK)) 1749 tcp_timer_activate(tp, TT_DELACK, 0); 1750 if (sendalot) 1751 goto again; 1752 return (0); 1753 } 1754 1755 void 1756 tcp_setpersist(struct tcpcb *tp) 1757 { 1758 int t = ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1; 1759 int tt; 1760 int maxunacktime; 1761 1762 tp->t_flags &= ~TF_PREVVALID; 1763 if (tcp_timer_active(tp, TT_REXMT)) 1764 panic("tcp_setpersist: retransmit pending"); 1765 /* 1766 * If the state is already closed, don't bother. 1767 */ 1768 if (tp->t_state == TCPS_CLOSED) 1769 return; 1770 1771 /* 1772 * Start/restart persistence timer. 1773 */ 1774 TCPT_RANGESET(tt, t * tcp_backoff[tp->t_rxtshift], 1775 tcp_persmin, tcp_persmax); 1776 if (TP_MAXUNACKTIME(tp) && tp->t_acktime) { 1777 maxunacktime = tp->t_acktime + TP_MAXUNACKTIME(tp) - ticks; 1778 if (maxunacktime < 1) 1779 maxunacktime = 1; 1780 if (maxunacktime < tt) 1781 tt = maxunacktime; 1782 } 1783 tcp_timer_activate(tp, TT_PERSIST, tt); 1784 if (tp->t_rxtshift < V_tcp_retries) 1785 tp->t_rxtshift++; 1786 } 1787 1788 /* 1789 * Insert TCP options according to the supplied parameters to the place 1790 * optp in a consistent way. Can handle unaligned destinations. 1791 * 1792 * The order of the option processing is crucial for optimal packing and 1793 * alignment for the scarce option space. 1794 * 1795 * The optimal order for a SYN/SYN-ACK segment is: 1796 * MSS (4) + NOP (1) + Window scale (3) + SACK permitted (2) + 1797 * Timestamp (10) + Signature (18) = 38 bytes out of a maximum of 40. 1798 * 1799 * The SACK options should be last. SACK blocks consume 8*n+2 bytes. 1800 * So a full size SACK blocks option is 34 bytes (with 4 SACK blocks). 1801 * At minimum we need 10 bytes (to generate 1 SACK block). If both 1802 * TCP Timestamps (12 bytes) and TCP Signatures (18 bytes) are present, 1803 * we only have 10 bytes for SACK options (40 - (12 + 18)). 1804 */ 1805 int 1806 tcp_addoptions(struct tcpopt *to, u_char *optp) 1807 { 1808 u_int32_t mask, optlen = 0; 1809 1810 for (mask = 1; mask < TOF_MAXOPT; mask <<= 1) { 1811 if ((to->to_flags & mask) != mask) 1812 continue; 1813 if (optlen == TCP_MAXOLEN) 1814 break; 1815 switch (to->to_flags & mask) { 1816 case TOF_MSS: 1817 while (optlen % 4) { 1818 optlen += TCPOLEN_NOP; 1819 *optp++ = TCPOPT_NOP; 1820 } 1821 if (TCP_MAXOLEN - optlen < TCPOLEN_MAXSEG) 1822 continue; 1823 optlen += TCPOLEN_MAXSEG; 1824 *optp++ = TCPOPT_MAXSEG; 1825 *optp++ = TCPOLEN_MAXSEG; 1826 to->to_mss = htons(to->to_mss); 1827 bcopy((u_char *)&to->to_mss, optp, sizeof(to->to_mss)); 1828 optp += sizeof(to->to_mss); 1829 break; 1830 case TOF_SCALE: 1831 while (!optlen || optlen % 2 != 1) { 1832 optlen += TCPOLEN_NOP; 1833 *optp++ = TCPOPT_NOP; 1834 } 1835 if (TCP_MAXOLEN - optlen < TCPOLEN_WINDOW) 1836 continue; 1837 optlen += TCPOLEN_WINDOW; 1838 *optp++ = TCPOPT_WINDOW; 1839 *optp++ = TCPOLEN_WINDOW; 1840 *optp++ = to->to_wscale; 1841 break; 1842 case TOF_SACKPERM: 1843 while (optlen % 2) { 1844 optlen += TCPOLEN_NOP; 1845 *optp++ = TCPOPT_NOP; 1846 } 1847 if (TCP_MAXOLEN - optlen < TCPOLEN_SACK_PERMITTED) 1848 continue; 1849 optlen += TCPOLEN_SACK_PERMITTED; 1850 *optp++ = TCPOPT_SACK_PERMITTED; 1851 *optp++ = TCPOLEN_SACK_PERMITTED; 1852 break; 1853 case TOF_TS: 1854 while (!optlen || optlen % 4 != 2) { 1855 optlen += TCPOLEN_NOP; 1856 *optp++ = TCPOPT_NOP; 1857 } 1858 if (TCP_MAXOLEN - optlen < TCPOLEN_TIMESTAMP) 1859 continue; 1860 optlen += TCPOLEN_TIMESTAMP; 1861 *optp++ = TCPOPT_TIMESTAMP; 1862 *optp++ = TCPOLEN_TIMESTAMP; 1863 to->to_tsval = htonl(to->to_tsval); 1864 to->to_tsecr = htonl(to->to_tsecr); 1865 bcopy((u_char *)&to->to_tsval, optp, sizeof(to->to_tsval)); 1866 optp += sizeof(to->to_tsval); 1867 bcopy((u_char *)&to->to_tsecr, optp, sizeof(to->to_tsecr)); 1868 optp += sizeof(to->to_tsecr); 1869 break; 1870 case TOF_SIGNATURE: 1871 { 1872 int siglen = TCPOLEN_SIGNATURE - 2; 1873 1874 while (!optlen || optlen % 4 != 2) { 1875 optlen += TCPOLEN_NOP; 1876 *optp++ = TCPOPT_NOP; 1877 } 1878 if (TCP_MAXOLEN - optlen < TCPOLEN_SIGNATURE) { 1879 to->to_flags &= ~TOF_SIGNATURE; 1880 continue; 1881 } 1882 optlen += TCPOLEN_SIGNATURE; 1883 *optp++ = TCPOPT_SIGNATURE; 1884 *optp++ = TCPOLEN_SIGNATURE; 1885 to->to_signature = optp; 1886 while (siglen--) 1887 *optp++ = 0; 1888 break; 1889 } 1890 case TOF_SACK: 1891 { 1892 int sackblks = 0; 1893 struct sackblk *sack = (struct sackblk *)to->to_sacks; 1894 tcp_seq sack_seq; 1895 1896 while (!optlen || optlen % 4 != 2) { 1897 optlen += TCPOLEN_NOP; 1898 *optp++ = TCPOPT_NOP; 1899 } 1900 if (TCP_MAXOLEN - optlen < TCPOLEN_SACKHDR + TCPOLEN_SACK) 1901 continue; 1902 optlen += TCPOLEN_SACKHDR; 1903 *optp++ = TCPOPT_SACK; 1904 sackblks = min(to->to_nsacks, 1905 (TCP_MAXOLEN - optlen) / TCPOLEN_SACK); 1906 *optp++ = TCPOLEN_SACKHDR + sackblks * TCPOLEN_SACK; 1907 while (sackblks--) { 1908 sack_seq = htonl(sack->start); 1909 bcopy((u_char *)&sack_seq, optp, sizeof(sack_seq)); 1910 optp += sizeof(sack_seq); 1911 sack_seq = htonl(sack->end); 1912 bcopy((u_char *)&sack_seq, optp, sizeof(sack_seq)); 1913 optp += sizeof(sack_seq); 1914 optlen += TCPOLEN_SACK; 1915 sack++; 1916 } 1917 TCPSTAT_INC(tcps_sack_send_blocks); 1918 break; 1919 } 1920 case TOF_FASTOPEN: 1921 { 1922 int total_len; 1923 1924 /* XXX is there any point to aligning this option? */ 1925 total_len = TCPOLEN_FAST_OPEN_EMPTY + to->to_tfo_len; 1926 if (TCP_MAXOLEN - optlen < total_len) { 1927 to->to_flags &= ~TOF_FASTOPEN; 1928 continue; 1929 } 1930 *optp++ = TCPOPT_FAST_OPEN; 1931 *optp++ = total_len; 1932 if (to->to_tfo_len > 0) { 1933 bcopy(to->to_tfo_cookie, optp, to->to_tfo_len); 1934 optp += to->to_tfo_len; 1935 } 1936 optlen += total_len; 1937 break; 1938 } 1939 default: 1940 panic("%s: unknown TCP option type", __func__); 1941 break; 1942 } 1943 } 1944 1945 /* Terminate and pad TCP options to a 4 byte boundary. */ 1946 if (optlen % 4) { 1947 optlen += TCPOLEN_EOL; 1948 *optp++ = TCPOPT_EOL; 1949 } 1950 /* 1951 * According to RFC 793 (STD0007): 1952 * "The content of the header beyond the End-of-Option option 1953 * must be header padding (i.e., zero)." 1954 * and later: "The padding is composed of zeros." 1955 */ 1956 while (optlen % 4) { 1957 optlen += TCPOLEN_PAD; 1958 *optp++ = TCPOPT_PAD; 1959 } 1960 1961 KASSERT(optlen <= TCP_MAXOLEN, ("%s: TCP options too long", __func__)); 1962 return (optlen); 1963 } 1964 1965 /* 1966 * This is a copy of m_copym(), taking the TSO segment size/limit 1967 * constraints into account, and advancing the sndptr as it goes. 1968 */ 1969 struct mbuf * 1970 tcp_m_copym(struct mbuf *m, int32_t off0, int32_t *plen, 1971 int32_t seglimit, int32_t segsize, struct sockbuf *sb, bool hw_tls) 1972 { 1973 #ifdef KERN_TLS 1974 struct ktls_session *tls, *ntls; 1975 struct mbuf *start __diagused; 1976 #endif 1977 struct mbuf *n, **np; 1978 struct mbuf *top; 1979 int32_t off = off0; 1980 int32_t len = *plen; 1981 int32_t fragsize; 1982 int32_t len_cp = 0; 1983 int32_t *pkthdrlen; 1984 uint32_t mlen, frags; 1985 bool copyhdr; 1986 1987 KASSERT(off >= 0, ("tcp_m_copym, negative off %d", off)); 1988 KASSERT(len >= 0, ("tcp_m_copym, negative len %d", len)); 1989 if (off == 0 && m->m_flags & M_PKTHDR) 1990 copyhdr = true; 1991 else 1992 copyhdr = false; 1993 while (off > 0) { 1994 KASSERT(m != NULL, ("tcp_m_copym, offset > size of mbuf chain")); 1995 if (off < m->m_len) 1996 break; 1997 off -= m->m_len; 1998 if ((sb) && (m == sb->sb_sndptr)) { 1999 sb->sb_sndptroff += m->m_len; 2000 sb->sb_sndptr = m->m_next; 2001 } 2002 m = m->m_next; 2003 } 2004 np = ⊤ 2005 top = NULL; 2006 pkthdrlen = NULL; 2007 #ifdef KERN_TLS 2008 if (hw_tls && (m->m_flags & M_EXTPG)) 2009 tls = m->m_epg_tls; 2010 else 2011 tls = NULL; 2012 start = m; 2013 #endif 2014 while (len > 0) { 2015 if (m == NULL) { 2016 KASSERT(len == M_COPYALL, 2017 ("tcp_m_copym, length > size of mbuf chain")); 2018 *plen = len_cp; 2019 if (pkthdrlen != NULL) 2020 *pkthdrlen = len_cp; 2021 break; 2022 } 2023 #ifdef KERN_TLS 2024 if (hw_tls) { 2025 if (m->m_flags & M_EXTPG) 2026 ntls = m->m_epg_tls; 2027 else 2028 ntls = NULL; 2029 2030 /* 2031 * Avoid mixing TLS records with handshake 2032 * data or TLS records from different 2033 * sessions. 2034 */ 2035 if (tls != ntls) { 2036 MPASS(m != start); 2037 *plen = len_cp; 2038 if (pkthdrlen != NULL) 2039 *pkthdrlen = len_cp; 2040 break; 2041 } 2042 } 2043 #endif 2044 mlen = min(len, m->m_len - off); 2045 if (seglimit) { 2046 /* 2047 * For M_EXTPG mbufs, add 3 segments 2048 * + 1 in case we are crossing page boundaries 2049 * + 2 in case the TLS hdr/trailer are used 2050 * It is cheaper to just add the segments 2051 * than it is to take the cache miss to look 2052 * at the mbuf ext_pgs state in detail. 2053 */ 2054 if (m->m_flags & M_EXTPG) { 2055 fragsize = min(segsize, PAGE_SIZE); 2056 frags = 3; 2057 } else { 2058 fragsize = segsize; 2059 frags = 0; 2060 } 2061 2062 /* Break if we really can't fit anymore. */ 2063 if ((frags + 1) >= seglimit) { 2064 *plen = len_cp; 2065 if (pkthdrlen != NULL) 2066 *pkthdrlen = len_cp; 2067 break; 2068 } 2069 2070 /* 2071 * Reduce size if you can't copy the whole 2072 * mbuf. If we can't copy the whole mbuf, also 2073 * adjust len so the loop will end after this 2074 * mbuf. 2075 */ 2076 if ((frags + howmany(mlen, fragsize)) >= seglimit) { 2077 mlen = (seglimit - frags - 1) * fragsize; 2078 len = mlen; 2079 *plen = len_cp + len; 2080 if (pkthdrlen != NULL) 2081 *pkthdrlen = *plen; 2082 } 2083 frags += howmany(mlen, fragsize); 2084 if (frags == 0) 2085 frags++; 2086 seglimit -= frags; 2087 KASSERT(seglimit > 0, 2088 ("%s: seglimit went too low", __func__)); 2089 } 2090 if (copyhdr) 2091 n = m_gethdr(M_NOWAIT, m->m_type); 2092 else 2093 n = m_get(M_NOWAIT, m->m_type); 2094 *np = n; 2095 if (n == NULL) 2096 goto nospace; 2097 if (copyhdr) { 2098 if (!m_dup_pkthdr(n, m, M_NOWAIT)) 2099 goto nospace; 2100 if (len == M_COPYALL) 2101 n->m_pkthdr.len -= off0; 2102 else 2103 n->m_pkthdr.len = len; 2104 pkthdrlen = &n->m_pkthdr.len; 2105 copyhdr = false; 2106 } 2107 n->m_len = mlen; 2108 len_cp += n->m_len; 2109 if (m->m_flags & (M_EXT | M_EXTPG)) { 2110 n->m_data = m->m_data + off; 2111 mb_dupcl(n, m); 2112 } else 2113 bcopy(mtod(m, caddr_t)+off, mtod(n, caddr_t), 2114 (u_int)n->m_len); 2115 2116 if (sb && (sb->sb_sndptr == m) && 2117 ((n->m_len + off) >= m->m_len) && m->m_next) { 2118 sb->sb_sndptroff += m->m_len; 2119 sb->sb_sndptr = m->m_next; 2120 } 2121 off = 0; 2122 if (len != M_COPYALL) { 2123 len -= n->m_len; 2124 } 2125 m = m->m_next; 2126 np = &n->m_next; 2127 } 2128 return (top); 2129 nospace: 2130 m_freem(top); 2131 return (NULL); 2132 } 2133 2134 void 2135 tcp_sndbuf_autoscale(struct tcpcb *tp, struct socket *so, uint32_t sendwin) 2136 { 2137 2138 /* 2139 * Automatic sizing of send socket buffer. Often the send buffer 2140 * size is not optimally adjusted to the actual network conditions 2141 * at hand (delay bandwidth product). Setting the buffer size too 2142 * small limits throughput on links with high bandwidth and high 2143 * delay (eg. trans-continental/oceanic links). Setting the 2144 * buffer size too big consumes too much real kernel memory, 2145 * especially with many connections on busy servers. 2146 * 2147 * The criteria to step up the send buffer one notch are: 2148 * 1. receive window of remote host is larger than send buffer 2149 * (with a fudge factor of 5/4th); 2150 * 2. send buffer is filled to 7/8th with data (so we actually 2151 * have data to make use of it); 2152 * 3. send buffer fill has not hit maximal automatic size; 2153 * 4. our send window (slow start and cogestion controlled) is 2154 * larger than sent but unacknowledged data in send buffer. 2155 * 2156 * The remote host receive window scaling factor may limit the 2157 * growing of the send buffer before it reaches its allowed 2158 * maximum. 2159 * 2160 * It scales directly with slow start or congestion window 2161 * and does at most one step per received ACK. This fast 2162 * scaling has the drawback of growing the send buffer beyond 2163 * what is strictly necessary to make full use of a given 2164 * delay*bandwidth product. However testing has shown this not 2165 * to be much of an problem. At worst we are trading wasting 2166 * of available bandwidth (the non-use of it) for wasting some 2167 * socket buffer memory. 2168 * 2169 * TODO: Shrink send buffer during idle periods together 2170 * with congestion window. Requires another timer. Has to 2171 * wait for upcoming tcp timer rewrite. 2172 * 2173 * XXXGL: should there be used sbused() or sbavail()? 2174 */ 2175 if (V_tcp_do_autosndbuf && so->so_snd.sb_flags & SB_AUTOSIZE) { 2176 int lowat; 2177 2178 lowat = V_tcp_sendbuf_auto_lowat ? so->so_snd.sb_lowat : 0; 2179 if ((tp->snd_wnd / 4 * 5) >= so->so_snd.sb_hiwat - lowat && 2180 sbused(&so->so_snd) >= 2181 (so->so_snd.sb_hiwat / 8 * 7) - lowat && 2182 sbused(&so->so_snd) < V_tcp_autosndbuf_max && 2183 sendwin >= (sbused(&so->so_snd) - 2184 (tp->snd_nxt - tp->snd_una))) { 2185 if (!sbreserve_locked(so, SO_SND, 2186 min(so->so_snd.sb_hiwat + V_tcp_autosndbuf_inc, 2187 V_tcp_autosndbuf_max), curthread)) 2188 so->so_snd.sb_flags &= ~SB_AUTOSIZE; 2189 } 2190 } 2191 } 2192