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