1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995 5 * The Regents of the University of California. All rights reserved. 6 * Copyright (c) 2007-2008,2010 7 * Swinburne University of Technology, Melbourne, Australia. 8 * Copyright (c) 2009-2010 Lawrence Stewart <lstewart@freebsd.org> 9 * Copyright (c) 2010 The FreeBSD Foundation 10 * Copyright (c) 2010-2011 Juniper Networks, Inc. 11 * All rights reserved. 12 * 13 * Portions of this software were developed at the Centre for Advanced Internet 14 * Architectures, Swinburne University of Technology, by Lawrence Stewart, 15 * James Healy and David Hayes, made possible in part by a grant from the Cisco 16 * University Research Program Fund at Community Foundation Silicon Valley. 17 * 18 * Portions of this software were developed at the Centre for Advanced 19 * Internet Architectures, Swinburne University of Technology, Melbourne, 20 * Australia by David Hayes under sponsorship from the FreeBSD Foundation. 21 * 22 * Portions of this software were developed by Robert N. M. Watson under 23 * contract to Juniper Networks, Inc. 24 * 25 * Redistribution and use in source and binary forms, with or without 26 * modification, are permitted provided that the following conditions 27 * are met: 28 * 1. Redistributions of source code must retain the above copyright 29 * notice, this list of conditions and the following disclaimer. 30 * 2. Redistributions in binary form must reproduce the above copyright 31 * notice, this list of conditions and the following disclaimer in the 32 * documentation and/or other materials provided with the distribution. 33 * 3. Neither the name of the University nor the names of its contributors 34 * may be used to endorse or promote products derived from this software 35 * without specific prior written permission. 36 * 37 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 38 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 39 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 40 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 41 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 42 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 43 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 44 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 45 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 46 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 47 * SUCH DAMAGE. 48 * 49 * @(#)tcp_input.c 8.12 (Berkeley) 5/24/95 50 */ 51 52 #include <sys/cdefs.h> 53 __FBSDID("$FreeBSD$"); 54 55 #include "opt_inet.h" 56 #include "opt_inet6.h" 57 #include "opt_ipsec.h" 58 #include "opt_tcpdebug.h" 59 60 #include <sys/param.h> 61 #include <sys/arb.h> 62 #include <sys/kernel.h> 63 #ifdef TCP_HHOOK 64 #include <sys/hhook.h> 65 #endif 66 #include <sys/malloc.h> 67 #include <sys/mbuf.h> 68 #include <sys/proc.h> /* for proc0 declaration */ 69 #include <sys/protosw.h> 70 #include <sys/qmath.h> 71 #include <sys/sdt.h> 72 #include <sys/signalvar.h> 73 #include <sys/socket.h> 74 #include <sys/socketvar.h> 75 #include <sys/sysctl.h> 76 #include <sys/syslog.h> 77 #include <sys/systm.h> 78 #include <sys/stats.h> 79 80 #include <machine/cpu.h> /* before tcp_seq.h, for tcp_random18() */ 81 82 #include <vm/uma.h> 83 84 #include <net/if.h> 85 #include <net/if_var.h> 86 #include <net/route.h> 87 #include <net/vnet.h> 88 89 #define TCPSTATES /* for logging */ 90 91 #include <netinet/in.h> 92 #include <netinet/in_kdtrace.h> 93 #include <netinet/in_pcb.h> 94 #include <netinet/in_systm.h> 95 #include <netinet/ip.h> 96 #include <netinet/ip_icmp.h> /* required for icmp_var.h */ 97 #include <netinet/icmp_var.h> /* for ICMP_BANDLIM */ 98 #include <netinet/ip_var.h> 99 #include <netinet/ip_options.h> 100 #include <netinet/ip6.h> 101 #include <netinet/icmp6.h> 102 #include <netinet6/in6_pcb.h> 103 #include <netinet6/in6_var.h> 104 #include <netinet6/ip6_var.h> 105 #include <netinet6/nd6.h> 106 #include <netinet/tcp.h> 107 #include <netinet/tcp_fsm.h> 108 #include <netinet/tcp_log_buf.h> 109 #include <netinet/tcp_seq.h> 110 #include <netinet/tcp_timer.h> 111 #include <netinet/tcp_var.h> 112 #include <netinet6/tcp6_var.h> 113 #include <netinet/tcpip.h> 114 #include <netinet/cc/cc.h> 115 #include <netinet/tcp_fastopen.h> 116 #ifdef TCPPCAP 117 #include <netinet/tcp_pcap.h> 118 #endif 119 #include <netinet/tcp_syncache.h> 120 #ifdef TCPDEBUG 121 #include <netinet/tcp_debug.h> 122 #endif /* TCPDEBUG */ 123 #ifdef TCP_OFFLOAD 124 #include <netinet/tcp_offload.h> 125 #endif 126 127 #include <netipsec/ipsec_support.h> 128 129 #include <machine/in_cksum.h> 130 131 #include <security/mac/mac_framework.h> 132 133 const int tcprexmtthresh = 3; 134 135 VNET_DEFINE(int, tcp_log_in_vain) = 0; 136 SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_in_vain, CTLFLAG_VNET | CTLFLAG_RW, 137 &VNET_NAME(tcp_log_in_vain), 0, 138 "Log all incoming TCP segments to closed ports"); 139 140 VNET_DEFINE(int, blackhole) = 0; 141 #define V_blackhole VNET(blackhole) 142 SYSCTL_INT(_net_inet_tcp, OID_AUTO, blackhole, CTLFLAG_VNET | CTLFLAG_RW, 143 &VNET_NAME(blackhole), 0, 144 "Do not send RST on segments to closed ports"); 145 146 VNET_DEFINE(int, tcp_delack_enabled) = 1; 147 SYSCTL_INT(_net_inet_tcp, OID_AUTO, delayed_ack, CTLFLAG_VNET | CTLFLAG_RW, 148 &VNET_NAME(tcp_delack_enabled), 0, 149 "Delay ACK to try and piggyback it onto a data packet"); 150 151 VNET_DEFINE(int, drop_synfin) = 0; 152 SYSCTL_INT(_net_inet_tcp, OID_AUTO, drop_synfin, CTLFLAG_VNET | CTLFLAG_RW, 153 &VNET_NAME(drop_synfin), 0, 154 "Drop TCP packets with SYN+FIN set"); 155 156 VNET_DEFINE(int, tcp_do_prr_conservative) = 0; 157 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_prr_conservative, CTLFLAG_VNET | CTLFLAG_RW, 158 &VNET_NAME(tcp_do_prr_conservative), 0, 159 "Do conservative Proportional Rate Reduction"); 160 161 VNET_DEFINE(int, tcp_do_prr) = 1; 162 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_prr, CTLFLAG_VNET | CTLFLAG_RW, 163 &VNET_NAME(tcp_do_prr), 1, 164 "Enable Proportional Rate Reduction per RFC 6937"); 165 166 VNET_DEFINE(int, tcp_do_newcwv) = 0; 167 SYSCTL_INT(_net_inet_tcp, OID_AUTO, newcwv, CTLFLAG_VNET | CTLFLAG_RW, 168 &VNET_NAME(tcp_do_newcwv), 0, 169 "Enable New Congestion Window Validation per RFC7661"); 170 171 VNET_DEFINE(int, tcp_do_rfc6675_pipe) = 0; 172 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc6675_pipe, CTLFLAG_VNET | CTLFLAG_RW, 173 &VNET_NAME(tcp_do_rfc6675_pipe), 0, 174 "Use calculated pipe/in-flight bytes per RFC 6675"); 175 176 VNET_DEFINE(int, tcp_do_rfc3042) = 1; 177 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3042, CTLFLAG_VNET | CTLFLAG_RW, 178 &VNET_NAME(tcp_do_rfc3042), 0, 179 "Enable RFC 3042 (Limited Transmit)"); 180 181 VNET_DEFINE(int, tcp_do_rfc3390) = 1; 182 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3390, CTLFLAG_VNET | CTLFLAG_RW, 183 &VNET_NAME(tcp_do_rfc3390), 0, 184 "Enable RFC 3390 (Increasing TCP's Initial Congestion Window)"); 185 186 VNET_DEFINE(int, tcp_initcwnd_segments) = 10; 187 SYSCTL_INT(_net_inet_tcp, OID_AUTO, initcwnd_segments, 188 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(tcp_initcwnd_segments), 0, 189 "Slow-start flight size (initial congestion window) in number of segments"); 190 191 VNET_DEFINE(int, tcp_do_rfc3465) = 1; 192 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3465, CTLFLAG_VNET | CTLFLAG_RW, 193 &VNET_NAME(tcp_do_rfc3465), 0, 194 "Enable RFC 3465 (Appropriate Byte Counting)"); 195 196 VNET_DEFINE(int, tcp_abc_l_var) = 2; 197 SYSCTL_INT(_net_inet_tcp, OID_AUTO, abc_l_var, CTLFLAG_VNET | CTLFLAG_RW, 198 &VNET_NAME(tcp_abc_l_var), 2, 199 "Cap the max cwnd increment during slow-start to this number of segments"); 200 201 static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, ecn, 202 CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 203 "TCP ECN"); 204 205 VNET_DEFINE(int, tcp_do_ecn) = 2; 206 SYSCTL_INT(_net_inet_tcp_ecn, OID_AUTO, enable, CTLFLAG_VNET | CTLFLAG_RW, 207 &VNET_NAME(tcp_do_ecn), 0, 208 "TCP ECN support"); 209 210 VNET_DEFINE(int, tcp_ecn_maxretries) = 1; 211 SYSCTL_INT(_net_inet_tcp_ecn, OID_AUTO, maxretries, CTLFLAG_VNET | CTLFLAG_RW, 212 &VNET_NAME(tcp_ecn_maxretries), 0, 213 "Max retries before giving up on ECN"); 214 215 VNET_DEFINE(int, tcp_insecure_syn) = 0; 216 SYSCTL_INT(_net_inet_tcp, OID_AUTO, insecure_syn, CTLFLAG_VNET | CTLFLAG_RW, 217 &VNET_NAME(tcp_insecure_syn), 0, 218 "Follow RFC793 instead of RFC5961 criteria for accepting SYN packets"); 219 220 VNET_DEFINE(int, tcp_insecure_rst) = 0; 221 SYSCTL_INT(_net_inet_tcp, OID_AUTO, insecure_rst, CTLFLAG_VNET | CTLFLAG_RW, 222 &VNET_NAME(tcp_insecure_rst), 0, 223 "Follow RFC793 instead of RFC5961 criteria for accepting RST packets"); 224 225 VNET_DEFINE(int, tcp_recvspace) = 1024*64; 226 #define V_tcp_recvspace VNET(tcp_recvspace) 227 SYSCTL_INT(_net_inet_tcp, TCPCTL_RECVSPACE, recvspace, CTLFLAG_VNET | CTLFLAG_RW, 228 &VNET_NAME(tcp_recvspace), 0, "Initial receive socket buffer size"); 229 230 VNET_DEFINE(int, tcp_do_autorcvbuf) = 1; 231 SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_auto, CTLFLAG_VNET | CTLFLAG_RW, 232 &VNET_NAME(tcp_do_autorcvbuf), 0, 233 "Enable automatic receive buffer sizing"); 234 235 VNET_DEFINE(int, tcp_autorcvbuf_max) = 2*1024*1024; 236 SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_max, CTLFLAG_VNET | CTLFLAG_RW, 237 &VNET_NAME(tcp_autorcvbuf_max), 0, 238 "Max size of automatic receive buffer"); 239 240 VNET_DEFINE(struct inpcbhead, tcb); 241 #define tcb6 tcb /* for KAME src sync over BSD*'s */ 242 VNET_DEFINE(struct inpcbinfo, tcbinfo); 243 244 /* 245 * TCP statistics are stored in an array of counter(9)s, which size matches 246 * size of struct tcpstat. TCP running connection count is a regular array. 247 */ 248 VNET_PCPUSTAT_DEFINE(struct tcpstat, tcpstat); 249 SYSCTL_VNET_PCPUSTAT(_net_inet_tcp, TCPCTL_STATS, stats, struct tcpstat, 250 tcpstat, "TCP statistics (struct tcpstat, netinet/tcp_var.h)"); 251 VNET_DEFINE(counter_u64_t, tcps_states[TCP_NSTATES]); 252 SYSCTL_COUNTER_U64_ARRAY(_net_inet_tcp, TCPCTL_STATES, states, CTLFLAG_RD | 253 CTLFLAG_VNET, &VNET_NAME(tcps_states)[0], TCP_NSTATES, 254 "TCP connection counts by TCP state"); 255 256 static void 257 tcp_vnet_init(const void *unused) 258 { 259 260 COUNTER_ARRAY_ALLOC(V_tcps_states, TCP_NSTATES, M_WAITOK); 261 VNET_PCPUSTAT_ALLOC(tcpstat, M_WAITOK); 262 } 263 VNET_SYSINIT(tcp_vnet_init, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY, 264 tcp_vnet_init, NULL); 265 266 #ifdef VIMAGE 267 static void 268 tcp_vnet_uninit(const void *unused) 269 { 270 271 COUNTER_ARRAY_FREE(V_tcps_states, TCP_NSTATES); 272 VNET_PCPUSTAT_FREE(tcpstat); 273 } 274 VNET_SYSUNINIT(tcp_vnet_uninit, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY, 275 tcp_vnet_uninit, NULL); 276 #endif /* VIMAGE */ 277 278 /* 279 * Kernel module interface for updating tcpstat. The first argument is an index 280 * into tcpstat treated as an array. 281 */ 282 void 283 kmod_tcpstat_add(int statnum, int val) 284 { 285 286 counter_u64_add(VNET(tcpstat)[statnum], val); 287 } 288 289 #ifdef TCP_HHOOK 290 /* 291 * Wrapper for the TCP established input helper hook. 292 */ 293 void 294 hhook_run_tcp_est_in(struct tcpcb *tp, struct tcphdr *th, struct tcpopt *to) 295 { 296 struct tcp_hhook_data hhook_data; 297 298 if (V_tcp_hhh[HHOOK_TCP_EST_IN]->hhh_nhooks > 0) { 299 hhook_data.tp = tp; 300 hhook_data.th = th; 301 hhook_data.to = to; 302 303 hhook_run_hooks(V_tcp_hhh[HHOOK_TCP_EST_IN], &hhook_data, 304 tp->osd); 305 } 306 } 307 #endif 308 309 /* 310 * CC wrapper hook functions 311 */ 312 void 313 cc_ack_received(struct tcpcb *tp, struct tcphdr *th, uint16_t nsegs, 314 uint16_t type) 315 { 316 #ifdef STATS 317 int32_t gput; 318 #endif 319 320 INP_WLOCK_ASSERT(tp->t_inpcb); 321 322 tp->ccv->nsegs = nsegs; 323 tp->ccv->bytes_this_ack = BYTES_THIS_ACK(tp, th); 324 if ((!V_tcp_do_newcwv && (tp->snd_cwnd <= tp->snd_wnd)) || 325 (V_tcp_do_newcwv && (tp->snd_cwnd <= tp->snd_wnd) && 326 (tp->snd_cwnd < (tcp_compute_pipe(tp) * 2)))) 327 tp->ccv->flags |= CCF_CWND_LIMITED; 328 else 329 tp->ccv->flags &= ~CCF_CWND_LIMITED; 330 331 if (type == CC_ACK) { 332 #ifdef STATS 333 stats_voi_update_abs_s32(tp->t_stats, VOI_TCP_CALCFRWINDIFF, 334 ((int32_t)tp->snd_cwnd) - tp->snd_wnd); 335 if (!IN_RECOVERY(tp->t_flags)) 336 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_ACKLEN, 337 tp->ccv->bytes_this_ack / (tcp_maxseg(tp) * nsegs)); 338 if ((tp->t_flags & TF_GPUTINPROG) && 339 SEQ_GEQ(th->th_ack, tp->gput_ack)) { 340 /* 341 * Compute goodput in bits per millisecond. 342 */ 343 gput = (((int64_t)(th->th_ack - tp->gput_seq)) << 3) / 344 max(1, tcp_ts_getticks() - tp->gput_ts); 345 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_GPUT, 346 gput); 347 /* 348 * XXXLAS: This is a temporary hack, and should be 349 * chained off VOI_TCP_GPUT when stats(9) grows an API 350 * to deal with chained VOIs. 351 */ 352 if (tp->t_stats_gput_prev > 0) 353 stats_voi_update_abs_s32(tp->t_stats, 354 VOI_TCP_GPUT_ND, 355 ((gput - tp->t_stats_gput_prev) * 100) / 356 tp->t_stats_gput_prev); 357 tp->t_flags &= ~TF_GPUTINPROG; 358 tp->t_stats_gput_prev = gput; 359 } 360 #endif /* STATS */ 361 if (tp->snd_cwnd > tp->snd_ssthresh) { 362 tp->t_bytes_acked += tp->ccv->bytes_this_ack; 363 if (tp->t_bytes_acked >= tp->snd_cwnd) { 364 tp->t_bytes_acked -= tp->snd_cwnd; 365 tp->ccv->flags |= CCF_ABC_SENTAWND; 366 } 367 } else { 368 tp->ccv->flags &= ~CCF_ABC_SENTAWND; 369 tp->t_bytes_acked = 0; 370 } 371 } 372 373 if (CC_ALGO(tp)->ack_received != NULL) { 374 /* XXXLAS: Find a way to live without this */ 375 tp->ccv->curack = th->th_ack; 376 CC_ALGO(tp)->ack_received(tp->ccv, type); 377 } 378 #ifdef STATS 379 stats_voi_update_abs_ulong(tp->t_stats, VOI_TCP_LCWIN, tp->snd_cwnd); 380 #endif 381 } 382 383 void 384 cc_conn_init(struct tcpcb *tp) 385 { 386 struct hc_metrics_lite metrics; 387 struct inpcb *inp = tp->t_inpcb; 388 u_int maxseg; 389 int rtt; 390 391 INP_WLOCK_ASSERT(tp->t_inpcb); 392 393 tcp_hc_get(&inp->inp_inc, &metrics); 394 maxseg = tcp_maxseg(tp); 395 396 if (tp->t_srtt == 0 && (rtt = metrics.rmx_rtt)) { 397 tp->t_srtt = rtt; 398 tp->t_rttbest = tp->t_srtt + TCP_RTT_SCALE; 399 TCPSTAT_INC(tcps_usedrtt); 400 if (metrics.rmx_rttvar) { 401 tp->t_rttvar = metrics.rmx_rttvar; 402 TCPSTAT_INC(tcps_usedrttvar); 403 } else { 404 /* default variation is +- 1 rtt */ 405 tp->t_rttvar = 406 tp->t_srtt * TCP_RTTVAR_SCALE / TCP_RTT_SCALE; 407 } 408 TCPT_RANGESET(tp->t_rxtcur, 409 ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1, 410 tp->t_rttmin, TCPTV_REXMTMAX); 411 } 412 if (metrics.rmx_ssthresh) { 413 /* 414 * There's some sort of gateway or interface 415 * buffer limit on the path. Use this to set 416 * the slow start threshold, but set the 417 * threshold to no less than 2*mss. 418 */ 419 tp->snd_ssthresh = max(2 * maxseg, metrics.rmx_ssthresh); 420 TCPSTAT_INC(tcps_usedssthresh); 421 } 422 423 /* 424 * Set the initial slow-start flight size. 425 * 426 * If a SYN or SYN/ACK was lost and retransmitted, we have to 427 * reduce the initial CWND to one segment as congestion is likely 428 * requiring us to be cautious. 429 */ 430 if (tp->snd_cwnd == 1) 431 tp->snd_cwnd = maxseg; /* SYN(-ACK) lost */ 432 else 433 tp->snd_cwnd = tcp_compute_initwnd(maxseg); 434 435 if (CC_ALGO(tp)->conn_init != NULL) 436 CC_ALGO(tp)->conn_init(tp->ccv); 437 } 438 439 void inline 440 cc_cong_signal(struct tcpcb *tp, struct tcphdr *th, uint32_t type) 441 { 442 INP_WLOCK_ASSERT(tp->t_inpcb); 443 444 #ifdef STATS 445 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_CSIG, type); 446 #endif 447 448 switch(type) { 449 case CC_NDUPACK: 450 if (!IN_FASTRECOVERY(tp->t_flags)) { 451 tp->snd_recover = tp->snd_max; 452 if (tp->t_flags2 & TF2_ECN_PERMIT) 453 tp->t_flags2 |= TF2_ECN_SND_CWR; 454 } 455 break; 456 case CC_ECN: 457 if (!IN_CONGRECOVERY(tp->t_flags) || 458 /* 459 * Allow ECN reaction on ACK to CWR, if 460 * that data segment was also CE marked. 461 */ 462 SEQ_GEQ(th->th_ack, tp->snd_recover)) { 463 EXIT_CONGRECOVERY(tp->t_flags); 464 TCPSTAT_INC(tcps_ecn_rcwnd); 465 tp->snd_recover = tp->snd_max + 1; 466 if (tp->t_flags2 & TF2_ECN_PERMIT) 467 tp->t_flags2 |= TF2_ECN_SND_CWR; 468 } 469 break; 470 case CC_RTO: 471 tp->t_dupacks = 0; 472 tp->t_bytes_acked = 0; 473 EXIT_RECOVERY(tp->t_flags); 474 if (tp->t_flags2 & TF2_ECN_PERMIT) 475 tp->t_flags2 |= TF2_ECN_SND_CWR; 476 break; 477 case CC_RTO_ERR: 478 TCPSTAT_INC(tcps_sndrexmitbad); 479 /* RTO was unnecessary, so reset everything. */ 480 tp->snd_cwnd = tp->snd_cwnd_prev; 481 tp->snd_ssthresh = tp->snd_ssthresh_prev; 482 tp->snd_recover = tp->snd_recover_prev; 483 if (tp->t_flags & TF_WASFRECOVERY) 484 ENTER_FASTRECOVERY(tp->t_flags); 485 if (tp->t_flags & TF_WASCRECOVERY) 486 ENTER_CONGRECOVERY(tp->t_flags); 487 tp->snd_nxt = tp->snd_max; 488 tp->t_flags &= ~TF_PREVVALID; 489 tp->t_badrxtwin = 0; 490 break; 491 } 492 493 if (CC_ALGO(tp)->cong_signal != NULL) { 494 if (th != NULL) 495 tp->ccv->curack = th->th_ack; 496 CC_ALGO(tp)->cong_signal(tp->ccv, type); 497 } 498 } 499 500 void inline 501 cc_post_recovery(struct tcpcb *tp, struct tcphdr *th) 502 { 503 INP_WLOCK_ASSERT(tp->t_inpcb); 504 505 /* XXXLAS: KASSERT that we're in recovery? */ 506 507 if (CC_ALGO(tp)->post_recovery != NULL) { 508 tp->ccv->curack = th->th_ack; 509 CC_ALGO(tp)->post_recovery(tp->ccv); 510 } 511 /* XXXLAS: EXIT_RECOVERY ? */ 512 tp->t_bytes_acked = 0; 513 tp->sackhint.prr_out = 0; 514 } 515 516 /* 517 * Indicate whether this ack should be delayed. We can delay the ack if 518 * following conditions are met: 519 * - There is no delayed ack timer in progress. 520 * - Our last ack wasn't a 0-sized window. We never want to delay 521 * the ack that opens up a 0-sized window. 522 * - LRO wasn't used for this segment. We make sure by checking that the 523 * segment size is not larger than the MSS. 524 */ 525 #define DELAY_ACK(tp, tlen) \ 526 ((!tcp_timer_active(tp, TT_DELACK) && \ 527 (tp->t_flags & TF_RXWIN0SENT) == 0) && \ 528 (tlen <= tp->t_maxseg) && \ 529 (V_tcp_delack_enabled || (tp->t_flags & TF_NEEDSYN))) 530 531 void inline 532 cc_ecnpkt_handler(struct tcpcb *tp, struct tcphdr *th, uint8_t iptos) 533 { 534 INP_WLOCK_ASSERT(tp->t_inpcb); 535 536 if (CC_ALGO(tp)->ecnpkt_handler != NULL) { 537 switch (iptos & IPTOS_ECN_MASK) { 538 case IPTOS_ECN_CE: 539 tp->ccv->flags |= CCF_IPHDR_CE; 540 break; 541 case IPTOS_ECN_ECT0: 542 /* FALLTHROUGH */ 543 case IPTOS_ECN_ECT1: 544 /* FALLTHROUGH */ 545 case IPTOS_ECN_NOTECT: 546 tp->ccv->flags &= ~CCF_IPHDR_CE; 547 break; 548 } 549 550 if (th->th_flags & TH_CWR) 551 tp->ccv->flags |= CCF_TCPHDR_CWR; 552 else 553 tp->ccv->flags &= ~CCF_TCPHDR_CWR; 554 555 CC_ALGO(tp)->ecnpkt_handler(tp->ccv); 556 557 if (tp->ccv->flags & CCF_ACKNOW) { 558 tcp_timer_activate(tp, TT_DELACK, tcp_delacktime); 559 tp->t_flags |= TF_ACKNOW; 560 } 561 } 562 } 563 564 /* 565 * TCP input handling is split into multiple parts: 566 * tcp6_input is a thin wrapper around tcp_input for the extended 567 * ip6_protox[] call format in ip6_input 568 * tcp_input handles primary segment validation, inpcb lookup and 569 * SYN processing on listen sockets 570 * tcp_do_segment processes the ACK and text of the segment for 571 * establishing, established and closing connections 572 */ 573 #ifdef INET6 574 int 575 tcp6_input(struct mbuf **mp, int *offp, int proto) 576 { 577 struct mbuf *m; 578 struct in6_ifaddr *ia6; 579 struct ip6_hdr *ip6; 580 581 m = *mp; 582 if (m->m_len < *offp + sizeof(struct tcphdr)) { 583 m = m_pullup(m, *offp + sizeof(struct tcphdr)); 584 if (m == NULL) { 585 *mp = m; 586 TCPSTAT_INC(tcps_rcvshort); 587 return (IPPROTO_DONE); 588 } 589 } 590 591 /* 592 * draft-itojun-ipv6-tcp-to-anycast 593 * better place to put this in? 594 */ 595 ip6 = mtod(m, struct ip6_hdr *); 596 ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */, false); 597 if (ia6 && (ia6->ia6_flags & IN6_IFF_ANYCAST)) { 598 icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR, 599 (caddr_t)&ip6->ip6_dst - (caddr_t)ip6); 600 *mp = NULL; 601 return (IPPROTO_DONE); 602 } 603 604 *mp = m; 605 return (tcp_input(mp, offp, proto)); 606 } 607 #endif /* INET6 */ 608 609 int 610 tcp_input(struct mbuf **mp, int *offp, int proto) 611 { 612 struct mbuf *m = *mp; 613 struct tcphdr *th = NULL; 614 struct ip *ip = NULL; 615 struct inpcb *inp = NULL; 616 struct tcpcb *tp = NULL; 617 struct socket *so = NULL; 618 u_char *optp = NULL; 619 int off0; 620 int optlen = 0; 621 #ifdef INET 622 int len; 623 uint8_t ipttl; 624 #endif 625 int tlen = 0, off; 626 int drop_hdrlen; 627 int thflags; 628 int rstreason = 0; /* For badport_bandlim accounting purposes */ 629 uint8_t iptos; 630 struct m_tag *fwd_tag = NULL; 631 #ifdef INET6 632 struct ip6_hdr *ip6 = NULL; 633 int isipv6; 634 #else 635 const void *ip6 = NULL; 636 #endif /* INET6 */ 637 struct tcpopt to; /* options in this segment */ 638 char *s = NULL; /* address and port logging */ 639 #ifdef TCPDEBUG 640 /* 641 * The size of tcp_saveipgen must be the size of the max ip header, 642 * now IPv6. 643 */ 644 u_char tcp_saveipgen[IP6_HDR_LEN]; 645 struct tcphdr tcp_savetcp; 646 short ostate = 0; 647 #endif 648 649 NET_EPOCH_ASSERT(); 650 651 #ifdef INET6 652 isipv6 = (mtod(m, struct ip *)->ip_v == 6) ? 1 : 0; 653 #endif 654 655 off0 = *offp; 656 m = *mp; 657 *mp = NULL; 658 to.to_flags = 0; 659 TCPSTAT_INC(tcps_rcvtotal); 660 661 #ifdef INET6 662 if (isipv6) { 663 ip6 = mtod(m, struct ip6_hdr *); 664 th = (struct tcphdr *)((caddr_t)ip6 + off0); 665 tlen = sizeof(*ip6) + ntohs(ip6->ip6_plen) - off0; 666 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID_IPV6) { 667 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 668 th->th_sum = m->m_pkthdr.csum_data; 669 else 670 th->th_sum = in6_cksum_pseudo(ip6, tlen, 671 IPPROTO_TCP, m->m_pkthdr.csum_data); 672 th->th_sum ^= 0xffff; 673 } else 674 th->th_sum = in6_cksum(m, IPPROTO_TCP, off0, tlen); 675 if (th->th_sum) { 676 TCPSTAT_INC(tcps_rcvbadsum); 677 goto drop; 678 } 679 680 /* 681 * Be proactive about unspecified IPv6 address in source. 682 * As we use all-zero to indicate unbounded/unconnected pcb, 683 * unspecified IPv6 address can be used to confuse us. 684 * 685 * Note that packets with unspecified IPv6 destination is 686 * already dropped in ip6_input. 687 */ 688 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 689 /* XXX stat */ 690 goto drop; 691 } 692 iptos = IPV6_TRAFFIC_CLASS(ip6); 693 } 694 #endif 695 #if defined(INET) && defined(INET6) 696 else 697 #endif 698 #ifdef INET 699 { 700 /* 701 * Get IP and TCP header together in first mbuf. 702 * Note: IP leaves IP header in first mbuf. 703 */ 704 if (off0 > sizeof (struct ip)) { 705 ip_stripoptions(m); 706 off0 = sizeof(struct ip); 707 } 708 if (m->m_len < sizeof (struct tcpiphdr)) { 709 if ((m = m_pullup(m, sizeof (struct tcpiphdr))) 710 == NULL) { 711 TCPSTAT_INC(tcps_rcvshort); 712 return (IPPROTO_DONE); 713 } 714 } 715 ip = mtod(m, struct ip *); 716 th = (struct tcphdr *)((caddr_t)ip + off0); 717 tlen = ntohs(ip->ip_len) - off0; 718 719 iptos = ip->ip_tos; 720 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) { 721 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 722 th->th_sum = m->m_pkthdr.csum_data; 723 else 724 th->th_sum = in_pseudo(ip->ip_src.s_addr, 725 ip->ip_dst.s_addr, 726 htonl(m->m_pkthdr.csum_data + tlen + 727 IPPROTO_TCP)); 728 th->th_sum ^= 0xffff; 729 } else { 730 struct ipovly *ipov = (struct ipovly *)ip; 731 732 /* 733 * Checksum extended TCP header and data. 734 */ 735 len = off0 + tlen; 736 ipttl = ip->ip_ttl; 737 bzero(ipov->ih_x1, sizeof(ipov->ih_x1)); 738 ipov->ih_len = htons(tlen); 739 th->th_sum = in_cksum(m, len); 740 /* Reset length for SDT probes. */ 741 ip->ip_len = htons(len); 742 /* Reset TOS bits */ 743 ip->ip_tos = iptos; 744 /* Re-initialization for later version check */ 745 ip->ip_ttl = ipttl; 746 ip->ip_v = IPVERSION; 747 ip->ip_hl = off0 >> 2; 748 } 749 750 if (th->th_sum) { 751 TCPSTAT_INC(tcps_rcvbadsum); 752 goto drop; 753 } 754 } 755 #endif /* INET */ 756 757 /* 758 * Check that TCP offset makes sense, 759 * pull out TCP options and adjust length. XXX 760 */ 761 off = th->th_off << 2; 762 if (off < sizeof (struct tcphdr) || off > tlen) { 763 TCPSTAT_INC(tcps_rcvbadoff); 764 goto drop; 765 } 766 tlen -= off; /* tlen is used instead of ti->ti_len */ 767 if (off > sizeof (struct tcphdr)) { 768 #ifdef INET6 769 if (isipv6) { 770 if (m->m_len < off0 + off) { 771 m = m_pullup(m, off0 + off); 772 if (m == NULL) { 773 TCPSTAT_INC(tcps_rcvshort); 774 return (IPPROTO_DONE); 775 } 776 } 777 ip6 = mtod(m, struct ip6_hdr *); 778 th = (struct tcphdr *)((caddr_t)ip6 + off0); 779 } 780 #endif 781 #if defined(INET) && defined(INET6) 782 else 783 #endif 784 #ifdef INET 785 { 786 if (m->m_len < sizeof(struct ip) + off) { 787 if ((m = m_pullup(m, sizeof (struct ip) + off)) 788 == NULL) { 789 TCPSTAT_INC(tcps_rcvshort); 790 return (IPPROTO_DONE); 791 } 792 ip = mtod(m, struct ip *); 793 th = (struct tcphdr *)((caddr_t)ip + off0); 794 } 795 } 796 #endif 797 optlen = off - sizeof (struct tcphdr); 798 optp = (u_char *)(th + 1); 799 } 800 thflags = th->th_flags; 801 802 /* 803 * Convert TCP protocol specific fields to host format. 804 */ 805 tcp_fields_to_host(th); 806 807 /* 808 * Delay dropping TCP, IP headers, IPv6 ext headers, and TCP options. 809 */ 810 drop_hdrlen = off0 + off; 811 812 /* 813 * Grab info from PACKET_TAG_IPFORWARD tag prepended to the chain. 814 */ 815 if ( 816 #ifdef INET6 817 (isipv6 && (m->m_flags & M_IP6_NEXTHOP)) 818 #ifdef INET 819 || (!isipv6 && (m->m_flags & M_IP_NEXTHOP)) 820 #endif 821 #endif 822 #if defined(INET) && !defined(INET6) 823 (m->m_flags & M_IP_NEXTHOP) 824 #endif 825 ) 826 fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL); 827 828 findpcb: 829 #ifdef INET6 830 if (isipv6 && fwd_tag != NULL) { 831 struct sockaddr_in6 *next_hop6; 832 833 next_hop6 = (struct sockaddr_in6 *)(fwd_tag + 1); 834 /* 835 * Transparently forwarded. Pretend to be the destination. 836 * Already got one like this? 837 */ 838 inp = in6_pcblookup_mbuf(&V_tcbinfo, 839 &ip6->ip6_src, th->th_sport, &ip6->ip6_dst, th->th_dport, 840 INPLOOKUP_WLOCKPCB, m->m_pkthdr.rcvif, m); 841 if (!inp) { 842 /* 843 * It's new. Try to find the ambushing socket. 844 * Because we've rewritten the destination address, 845 * any hardware-generated hash is ignored. 846 */ 847 inp = in6_pcblookup(&V_tcbinfo, &ip6->ip6_src, 848 th->th_sport, &next_hop6->sin6_addr, 849 next_hop6->sin6_port ? ntohs(next_hop6->sin6_port) : 850 th->th_dport, INPLOOKUP_WILDCARD | 851 INPLOOKUP_WLOCKPCB, m->m_pkthdr.rcvif); 852 } 853 } else if (isipv6) { 854 inp = in6_pcblookup_mbuf(&V_tcbinfo, &ip6->ip6_src, 855 th->th_sport, &ip6->ip6_dst, th->th_dport, 856 INPLOOKUP_WILDCARD | INPLOOKUP_WLOCKPCB, 857 m->m_pkthdr.rcvif, m); 858 } 859 #endif /* INET6 */ 860 #if defined(INET6) && defined(INET) 861 else 862 #endif 863 #ifdef INET 864 if (fwd_tag != NULL) { 865 struct sockaddr_in *next_hop; 866 867 next_hop = (struct sockaddr_in *)(fwd_tag+1); 868 /* 869 * Transparently forwarded. Pretend to be the destination. 870 * already got one like this? 871 */ 872 inp = in_pcblookup_mbuf(&V_tcbinfo, ip->ip_src, th->th_sport, 873 ip->ip_dst, th->th_dport, INPLOOKUP_WLOCKPCB, 874 m->m_pkthdr.rcvif, m); 875 if (!inp) { 876 /* 877 * It's new. Try to find the ambushing socket. 878 * Because we've rewritten the destination address, 879 * any hardware-generated hash is ignored. 880 */ 881 inp = in_pcblookup(&V_tcbinfo, ip->ip_src, 882 th->th_sport, next_hop->sin_addr, 883 next_hop->sin_port ? ntohs(next_hop->sin_port) : 884 th->th_dport, INPLOOKUP_WILDCARD | 885 INPLOOKUP_WLOCKPCB, m->m_pkthdr.rcvif); 886 } 887 } else 888 inp = in_pcblookup_mbuf(&V_tcbinfo, ip->ip_src, 889 th->th_sport, ip->ip_dst, th->th_dport, 890 INPLOOKUP_WILDCARD | INPLOOKUP_WLOCKPCB, 891 m->m_pkthdr.rcvif, m); 892 #endif /* INET */ 893 894 /* 895 * If the INPCB does not exist then all data in the incoming 896 * segment is discarded and an appropriate RST is sent back. 897 * XXX MRT Send RST using which routing table? 898 */ 899 if (inp == NULL) { 900 /* 901 * Log communication attempts to ports that are not 902 * in use. 903 */ 904 if ((V_tcp_log_in_vain == 1 && (thflags & TH_SYN)) || 905 V_tcp_log_in_vain == 2) { 906 if ((s = tcp_log_vain(NULL, th, (void *)ip, ip6))) 907 log(LOG_INFO, "%s; %s: Connection attempt " 908 "to closed port\n", s, __func__); 909 } 910 /* 911 * When blackholing do not respond with a RST but 912 * completely ignore the segment and drop it. 913 */ 914 if ((V_blackhole == 1 && (thflags & TH_SYN)) || 915 V_blackhole == 2) 916 goto dropunlock; 917 918 rstreason = BANDLIM_RST_CLOSEDPORT; 919 goto dropwithreset; 920 } 921 INP_WLOCK_ASSERT(inp); 922 /* 923 * While waiting for inp lock during the lookup, another thread 924 * can have dropped the inpcb, in which case we need to loop back 925 * and try to find a new inpcb to deliver to. 926 */ 927 if (inp->inp_flags & INP_DROPPED) { 928 INP_WUNLOCK(inp); 929 inp = NULL; 930 goto findpcb; 931 } 932 if ((inp->inp_flowtype == M_HASHTYPE_NONE) && 933 (M_HASHTYPE_GET(m) != M_HASHTYPE_NONE) && 934 ((inp->inp_socket == NULL) || 935 (inp->inp_socket->so_options & SO_ACCEPTCONN) == 0)) { 936 inp->inp_flowid = m->m_pkthdr.flowid; 937 inp->inp_flowtype = M_HASHTYPE_GET(m); 938 } 939 #if defined(IPSEC) || defined(IPSEC_SUPPORT) 940 #ifdef INET6 941 if (isipv6 && IPSEC_ENABLED(ipv6) && 942 IPSEC_CHECK_POLICY(ipv6, m, inp) != 0) { 943 goto dropunlock; 944 } 945 #ifdef INET 946 else 947 #endif 948 #endif /* INET6 */ 949 #ifdef INET 950 if (IPSEC_ENABLED(ipv4) && 951 IPSEC_CHECK_POLICY(ipv4, m, inp) != 0) { 952 goto dropunlock; 953 } 954 #endif /* INET */ 955 #endif /* IPSEC */ 956 957 /* 958 * Check the minimum TTL for socket. 959 */ 960 if (inp->inp_ip_minttl != 0) { 961 #ifdef INET6 962 if (isipv6) { 963 if (inp->inp_ip_minttl > ip6->ip6_hlim) 964 goto dropunlock; 965 } else 966 #endif 967 if (inp->inp_ip_minttl > ip->ip_ttl) 968 goto dropunlock; 969 } 970 971 /* 972 * A previous connection in TIMEWAIT state is supposed to catch stray 973 * or duplicate segments arriving late. If this segment was a 974 * legitimate new connection attempt, the old INPCB gets removed and 975 * we can try again to find a listening socket. 976 * 977 * At this point, due to earlier optimism, we may hold only an inpcb 978 * lock, and not the inpcbinfo write lock. If so, we need to try to 979 * acquire it, or if that fails, acquire a reference on the inpcb, 980 * drop all locks, acquire a global write lock, and then re-acquire 981 * the inpcb lock. We may at that point discover that another thread 982 * has tried to free the inpcb, in which case we need to loop back 983 * and try to find a new inpcb to deliver to. 984 * 985 * XXXRW: It may be time to rethink timewait locking. 986 */ 987 if (inp->inp_flags & INP_TIMEWAIT) { 988 tcp_dooptions(&to, optp, optlen, 989 (thflags & TH_SYN) ? TO_SYN : 0); 990 /* 991 * NB: tcp_twcheck unlocks the INP and frees the mbuf. 992 */ 993 if (tcp_twcheck(inp, &to, th, m, tlen)) 994 goto findpcb; 995 return (IPPROTO_DONE); 996 } 997 /* 998 * The TCPCB may no longer exist if the connection is winding 999 * down or it is in the CLOSED state. Either way we drop the 1000 * segment and send an appropriate response. 1001 */ 1002 tp = intotcpcb(inp); 1003 if (tp == NULL || tp->t_state == TCPS_CLOSED) { 1004 rstreason = BANDLIM_RST_CLOSEDPORT; 1005 goto dropwithreset; 1006 } 1007 1008 #ifdef TCP_OFFLOAD 1009 if (tp->t_flags & TF_TOE) { 1010 tcp_offload_input(tp, m); 1011 m = NULL; /* consumed by the TOE driver */ 1012 goto dropunlock; 1013 } 1014 #endif 1015 1016 #ifdef MAC 1017 INP_WLOCK_ASSERT(inp); 1018 if (mac_inpcb_check_deliver(inp, m)) 1019 goto dropunlock; 1020 #endif 1021 so = inp->inp_socket; 1022 KASSERT(so != NULL, ("%s: so == NULL", __func__)); 1023 #ifdef TCPDEBUG 1024 if (so->so_options & SO_DEBUG) { 1025 ostate = tp->t_state; 1026 #ifdef INET6 1027 if (isipv6) { 1028 bcopy((char *)ip6, (char *)tcp_saveipgen, sizeof(*ip6)); 1029 } else 1030 #endif 1031 bcopy((char *)ip, (char *)tcp_saveipgen, sizeof(*ip)); 1032 tcp_savetcp = *th; 1033 } 1034 #endif /* TCPDEBUG */ 1035 /* 1036 * When the socket is accepting connections (the INPCB is in LISTEN 1037 * state) we look into the SYN cache if this is a new connection 1038 * attempt or the completion of a previous one. 1039 */ 1040 KASSERT(tp->t_state == TCPS_LISTEN || !(so->so_options & SO_ACCEPTCONN), 1041 ("%s: so accepting but tp %p not listening", __func__, tp)); 1042 if (tp->t_state == TCPS_LISTEN && (so->so_options & SO_ACCEPTCONN)) { 1043 struct in_conninfo inc; 1044 1045 bzero(&inc, sizeof(inc)); 1046 #ifdef INET6 1047 if (isipv6) { 1048 inc.inc_flags |= INC_ISIPV6; 1049 if (inp->inp_inc.inc_flags & INC_IPV6MINMTU) 1050 inc.inc_flags |= INC_IPV6MINMTU; 1051 inc.inc6_faddr = ip6->ip6_src; 1052 inc.inc6_laddr = ip6->ip6_dst; 1053 } else 1054 #endif 1055 { 1056 inc.inc_faddr = ip->ip_src; 1057 inc.inc_laddr = ip->ip_dst; 1058 } 1059 inc.inc_fport = th->th_sport; 1060 inc.inc_lport = th->th_dport; 1061 inc.inc_fibnum = so->so_fibnum; 1062 1063 /* 1064 * Check for an existing connection attempt in syncache if 1065 * the flag is only ACK. A successful lookup creates a new 1066 * socket appended to the listen queue in SYN_RECEIVED state. 1067 */ 1068 if ((thflags & (TH_RST|TH_ACK|TH_SYN)) == TH_ACK) { 1069 /* 1070 * Parse the TCP options here because 1071 * syncookies need access to the reflected 1072 * timestamp. 1073 */ 1074 tcp_dooptions(&to, optp, optlen, 0); 1075 /* 1076 * NB: syncache_expand() doesn't unlock 1077 * inp and tcpinfo locks. 1078 */ 1079 rstreason = syncache_expand(&inc, &to, th, &so, m); 1080 if (rstreason < 0) { 1081 /* 1082 * A failing TCP MD5 signature comparison 1083 * must result in the segment being dropped 1084 * and must not produce any response back 1085 * to the sender. 1086 */ 1087 goto dropunlock; 1088 } else if (rstreason == 0) { 1089 /* 1090 * No syncache entry or ACK was not 1091 * for our SYN/ACK. Send a RST. 1092 * NB: syncache did its own logging 1093 * of the failure cause. 1094 */ 1095 rstreason = BANDLIM_RST_OPENPORT; 1096 goto dropwithreset; 1097 } 1098 tfo_socket_result: 1099 if (so == NULL) { 1100 /* 1101 * We completed the 3-way handshake 1102 * but could not allocate a socket 1103 * either due to memory shortage, 1104 * listen queue length limits or 1105 * global socket limits. Send RST 1106 * or wait and have the remote end 1107 * retransmit the ACK for another 1108 * try. 1109 */ 1110 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1111 log(LOG_DEBUG, "%s; %s: Listen socket: " 1112 "Socket allocation failed due to " 1113 "limits or memory shortage, %s\n", 1114 s, __func__, 1115 V_tcp_sc_rst_sock_fail ? 1116 "sending RST" : "try again"); 1117 if (V_tcp_sc_rst_sock_fail) { 1118 rstreason = BANDLIM_UNLIMITED; 1119 goto dropwithreset; 1120 } else 1121 goto dropunlock; 1122 } 1123 /* 1124 * Socket is created in state SYN_RECEIVED. 1125 * Unlock the listen socket, lock the newly 1126 * created socket and update the tp variable. 1127 */ 1128 INP_WUNLOCK(inp); /* listen socket */ 1129 inp = sotoinpcb(so); 1130 /* 1131 * New connection inpcb is already locked by 1132 * syncache_expand(). 1133 */ 1134 INP_WLOCK_ASSERT(inp); 1135 tp = intotcpcb(inp); 1136 KASSERT(tp->t_state == TCPS_SYN_RECEIVED, 1137 ("%s: ", __func__)); 1138 /* 1139 * Process the segment and the data it 1140 * contains. tcp_do_segment() consumes 1141 * the mbuf chain and unlocks the inpcb. 1142 */ 1143 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1144 tp->t_fb->tfb_tcp_do_segment(m, th, so, tp, drop_hdrlen, tlen, 1145 iptos); 1146 return (IPPROTO_DONE); 1147 } 1148 /* 1149 * Segment flag validation for new connection attempts: 1150 * 1151 * Our (SYN|ACK) response was rejected. 1152 * Check with syncache and remove entry to prevent 1153 * retransmits. 1154 * 1155 * NB: syncache_chkrst does its own logging of failure 1156 * causes. 1157 */ 1158 if (thflags & TH_RST) { 1159 syncache_chkrst(&inc, th, m); 1160 goto dropunlock; 1161 } 1162 /* 1163 * We can't do anything without SYN. 1164 */ 1165 if ((thflags & TH_SYN) == 0) { 1166 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1167 log(LOG_DEBUG, "%s; %s: Listen socket: " 1168 "SYN is missing, segment ignored\n", 1169 s, __func__); 1170 TCPSTAT_INC(tcps_badsyn); 1171 goto dropunlock; 1172 } 1173 /* 1174 * (SYN|ACK) is bogus on a listen socket. 1175 */ 1176 if (thflags & TH_ACK) { 1177 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1178 log(LOG_DEBUG, "%s; %s: Listen socket: " 1179 "SYN|ACK invalid, segment rejected\n", 1180 s, __func__); 1181 syncache_badack(&inc); /* XXX: Not needed! */ 1182 TCPSTAT_INC(tcps_badsyn); 1183 rstreason = BANDLIM_RST_OPENPORT; 1184 goto dropwithreset; 1185 } 1186 /* 1187 * If the drop_synfin option is enabled, drop all 1188 * segments with both the SYN and FIN bits set. 1189 * This prevents e.g. nmap from identifying the 1190 * TCP/IP stack. 1191 * XXX: Poor reasoning. nmap has other methods 1192 * and is constantly refining its stack detection 1193 * strategies. 1194 * XXX: This is a violation of the TCP specification 1195 * and was used by RFC1644. 1196 */ 1197 if ((thflags & TH_FIN) && V_drop_synfin) { 1198 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1199 log(LOG_DEBUG, "%s; %s: Listen socket: " 1200 "SYN|FIN segment ignored (based on " 1201 "sysctl setting)\n", s, __func__); 1202 TCPSTAT_INC(tcps_badsyn); 1203 goto dropunlock; 1204 } 1205 /* 1206 * Segment's flags are (SYN) or (SYN|FIN). 1207 * 1208 * TH_PUSH, TH_URG, TH_ECE, TH_CWR are ignored 1209 * as they do not affect the state of the TCP FSM. 1210 * The data pointed to by TH_URG and th_urp is ignored. 1211 */ 1212 KASSERT((thflags & (TH_RST|TH_ACK)) == 0, 1213 ("%s: Listen socket: TH_RST or TH_ACK set", __func__)); 1214 KASSERT(thflags & (TH_SYN), 1215 ("%s: Listen socket: TH_SYN not set", __func__)); 1216 #ifdef INET6 1217 /* 1218 * If deprecated address is forbidden, 1219 * we do not accept SYN to deprecated interface 1220 * address to prevent any new inbound connection from 1221 * getting established. 1222 * When we do not accept SYN, we send a TCP RST, 1223 * with deprecated source address (instead of dropping 1224 * it). We compromise it as it is much better for peer 1225 * to send a RST, and RST will be the final packet 1226 * for the exchange. 1227 * 1228 * If we do not forbid deprecated addresses, we accept 1229 * the SYN packet. RFC2462 does not suggest dropping 1230 * SYN in this case. 1231 * If we decipher RFC2462 5.5.4, it says like this: 1232 * 1. use of deprecated addr with existing 1233 * communication is okay - "SHOULD continue to be 1234 * used" 1235 * 2. use of it with new communication: 1236 * (2a) "SHOULD NOT be used if alternate address 1237 * with sufficient scope is available" 1238 * (2b) nothing mentioned otherwise. 1239 * Here we fall into (2b) case as we have no choice in 1240 * our source address selection - we must obey the peer. 1241 * 1242 * The wording in RFC2462 is confusing, and there are 1243 * multiple description text for deprecated address 1244 * handling - worse, they are not exactly the same. 1245 * I believe 5.5.4 is the best one, so we follow 5.5.4. 1246 */ 1247 if (isipv6 && !V_ip6_use_deprecated) { 1248 struct in6_ifaddr *ia6; 1249 1250 ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */, false); 1251 if (ia6 != NULL && 1252 (ia6->ia6_flags & IN6_IFF_DEPRECATED)) { 1253 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1254 log(LOG_DEBUG, "%s; %s: Listen socket: " 1255 "Connection attempt to deprecated " 1256 "IPv6 address rejected\n", 1257 s, __func__); 1258 rstreason = BANDLIM_RST_OPENPORT; 1259 goto dropwithreset; 1260 } 1261 } 1262 #endif /* INET6 */ 1263 /* 1264 * Basic sanity checks on incoming SYN requests: 1265 * Don't respond if the destination is a link layer 1266 * broadcast according to RFC1122 4.2.3.10, p. 104. 1267 * If it is from this socket it must be forged. 1268 * Don't respond if the source or destination is a 1269 * global or subnet broad- or multicast address. 1270 * Note that it is quite possible to receive unicast 1271 * link-layer packets with a broadcast IP address. Use 1272 * in_broadcast() to find them. 1273 */ 1274 if (m->m_flags & (M_BCAST|M_MCAST)) { 1275 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1276 log(LOG_DEBUG, "%s; %s: Listen socket: " 1277 "Connection attempt from broad- or multicast " 1278 "link layer address ignored\n", s, __func__); 1279 goto dropunlock; 1280 } 1281 #ifdef INET6 1282 if (isipv6) { 1283 if (th->th_dport == th->th_sport && 1284 IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &ip6->ip6_src)) { 1285 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1286 log(LOG_DEBUG, "%s; %s: Listen socket: " 1287 "Connection attempt to/from self " 1288 "ignored\n", s, __func__); 1289 goto dropunlock; 1290 } 1291 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 1292 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) { 1293 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1294 log(LOG_DEBUG, "%s; %s: Listen socket: " 1295 "Connection attempt from/to multicast " 1296 "address ignored\n", s, __func__); 1297 goto dropunlock; 1298 } 1299 } 1300 #endif 1301 #if defined(INET) && defined(INET6) 1302 else 1303 #endif 1304 #ifdef INET 1305 { 1306 if (th->th_dport == th->th_sport && 1307 ip->ip_dst.s_addr == ip->ip_src.s_addr) { 1308 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1309 log(LOG_DEBUG, "%s; %s: Listen socket: " 1310 "Connection attempt from/to self " 1311 "ignored\n", s, __func__); 1312 goto dropunlock; 1313 } 1314 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || 1315 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 1316 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || 1317 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) { 1318 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1319 log(LOG_DEBUG, "%s; %s: Listen socket: " 1320 "Connection attempt from/to broad- " 1321 "or multicast address ignored\n", 1322 s, __func__); 1323 goto dropunlock; 1324 } 1325 } 1326 #endif 1327 /* 1328 * SYN appears to be valid. Create compressed TCP state 1329 * for syncache. 1330 */ 1331 #ifdef TCPDEBUG 1332 if (so->so_options & SO_DEBUG) 1333 tcp_trace(TA_INPUT, ostate, tp, 1334 (void *)tcp_saveipgen, &tcp_savetcp, 0); 1335 #endif 1336 TCP_PROBE3(debug__input, tp, th, m); 1337 tcp_dooptions(&to, optp, optlen, TO_SYN); 1338 if (syncache_add(&inc, &to, th, inp, &so, m, NULL, NULL, iptos)) 1339 goto tfo_socket_result; 1340 1341 /* 1342 * Entry added to syncache and mbuf consumed. 1343 * Only the listen socket is unlocked by syncache_add(). 1344 */ 1345 INP_INFO_WUNLOCK_ASSERT(&V_tcbinfo); 1346 return (IPPROTO_DONE); 1347 } else if (tp->t_state == TCPS_LISTEN) { 1348 /* 1349 * When a listen socket is torn down the SO_ACCEPTCONN 1350 * flag is removed first while connections are drained 1351 * from the accept queue in a unlock/lock cycle of the 1352 * ACCEPT_LOCK, opening a race condition allowing a SYN 1353 * attempt go through unhandled. 1354 */ 1355 goto dropunlock; 1356 } 1357 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 1358 if (tp->t_flags & TF_SIGNATURE) { 1359 tcp_dooptions(&to, optp, optlen, thflags); 1360 if ((to.to_flags & TOF_SIGNATURE) == 0) { 1361 TCPSTAT_INC(tcps_sig_err_nosigopt); 1362 goto dropunlock; 1363 } 1364 if (!TCPMD5_ENABLED() || 1365 TCPMD5_INPUT(m, th, to.to_signature) != 0) 1366 goto dropunlock; 1367 } 1368 #endif 1369 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1370 1371 /* 1372 * Segment belongs to a connection in SYN_SENT, ESTABLISHED or later 1373 * state. tcp_do_segment() always consumes the mbuf chain, unlocks 1374 * the inpcb, and unlocks pcbinfo. 1375 */ 1376 tp->t_fb->tfb_tcp_do_segment(m, th, so, tp, drop_hdrlen, tlen, iptos); 1377 return (IPPROTO_DONE); 1378 1379 dropwithreset: 1380 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1381 1382 if (inp != NULL) { 1383 tcp_dropwithreset(m, th, tp, tlen, rstreason); 1384 INP_WUNLOCK(inp); 1385 } else 1386 tcp_dropwithreset(m, th, NULL, tlen, rstreason); 1387 m = NULL; /* mbuf chain got consumed. */ 1388 goto drop; 1389 1390 dropunlock: 1391 if (m != NULL) 1392 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1393 1394 if (inp != NULL) 1395 INP_WUNLOCK(inp); 1396 1397 drop: 1398 INP_INFO_WUNLOCK_ASSERT(&V_tcbinfo); 1399 if (s != NULL) 1400 free(s, M_TCPLOG); 1401 if (m != NULL) 1402 m_freem(m); 1403 return (IPPROTO_DONE); 1404 } 1405 1406 /* 1407 * Automatic sizing of receive socket buffer. Often the send 1408 * buffer size is not optimally adjusted to the actual network 1409 * conditions at hand (delay bandwidth product). Setting the 1410 * buffer size too small limits throughput on links with high 1411 * bandwidth and high delay (eg. trans-continental/oceanic links). 1412 * 1413 * On the receive side the socket buffer memory is only rarely 1414 * used to any significant extent. This allows us to be much 1415 * more aggressive in scaling the receive socket buffer. For 1416 * the case that the buffer space is actually used to a large 1417 * extent and we run out of kernel memory we can simply drop 1418 * the new segments; TCP on the sender will just retransmit it 1419 * later. Setting the buffer size too big may only consume too 1420 * much kernel memory if the application doesn't read() from 1421 * the socket or packet loss or reordering makes use of the 1422 * reassembly queue. 1423 * 1424 * The criteria to step up the receive buffer one notch are: 1425 * 1. Application has not set receive buffer size with 1426 * SO_RCVBUF. Setting SO_RCVBUF clears SB_AUTOSIZE. 1427 * 2. the number of bytes received during 1/2 of an sRTT 1428 * is at least 3/8 of the current socket buffer size. 1429 * 3. receive buffer size has not hit maximal automatic size; 1430 * 1431 * If all of the criteria are met we increaset the socket buffer 1432 * by a 1/2 (bounded by the max). This allows us to keep ahead 1433 * of slow-start but also makes it so our peer never gets limited 1434 * by our rwnd which we then open up causing a burst. 1435 * 1436 * This algorithm does two steps per RTT at most and only if 1437 * we receive a bulk stream w/o packet losses or reorderings. 1438 * Shrinking the buffer during idle times is not necessary as 1439 * it doesn't consume any memory when idle. 1440 * 1441 * TODO: Only step up if the application is actually serving 1442 * the buffer to better manage the socket buffer resources. 1443 */ 1444 int 1445 tcp_autorcvbuf(struct mbuf *m, struct tcphdr *th, struct socket *so, 1446 struct tcpcb *tp, int tlen) 1447 { 1448 int newsize = 0; 1449 1450 if (V_tcp_do_autorcvbuf && (so->so_rcv.sb_flags & SB_AUTOSIZE) && 1451 tp->t_srtt != 0 && tp->rfbuf_ts != 0 && 1452 TCP_TS_TO_TICKS(tcp_ts_getticks() - tp->rfbuf_ts) > 1453 ((tp->t_srtt >> TCP_RTT_SHIFT)/2)) { 1454 if (tp->rfbuf_cnt > ((so->so_rcv.sb_hiwat / 2)/ 4 * 3) && 1455 so->so_rcv.sb_hiwat < V_tcp_autorcvbuf_max) { 1456 newsize = min((so->so_rcv.sb_hiwat + (so->so_rcv.sb_hiwat/2)), V_tcp_autorcvbuf_max); 1457 } 1458 TCP_PROBE6(receive__autoresize, NULL, tp, m, tp, th, newsize); 1459 1460 /* Start over with next RTT. */ 1461 tp->rfbuf_ts = 0; 1462 tp->rfbuf_cnt = 0; 1463 } else { 1464 tp->rfbuf_cnt += tlen; /* add up */ 1465 } 1466 return (newsize); 1467 } 1468 1469 void 1470 tcp_handle_wakeup(struct tcpcb *tp, struct socket *so) 1471 { 1472 /* 1473 * Since tp might be gone if the session entered 1474 * the TIME_WAIT state before coming here, we need 1475 * to check if the socket is still connected. 1476 */ 1477 if ((so->so_state & SS_ISCONNECTED) == 0) 1478 return; 1479 INP_LOCK_ASSERT(tp->t_inpcb); 1480 if (tp->t_flags & TF_WAKESOR) { 1481 tp->t_flags &= ~TF_WAKESOR; 1482 SOCKBUF_UNLOCK_ASSERT(&so->so_rcv); 1483 sorwakeup(so); 1484 } 1485 if (tp->t_flags & TF_WAKESOW) { 1486 tp->t_flags &= ~TF_WAKESOW; 1487 SOCKBUF_UNLOCK_ASSERT(&so->so_snd); 1488 sowwakeup(so); 1489 } 1490 } 1491 1492 void 1493 tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so, 1494 struct tcpcb *tp, int drop_hdrlen, int tlen, uint8_t iptos) 1495 { 1496 int thflags, acked, ourfinisacked, needoutput = 0, sack_changed; 1497 int rstreason, todrop, win, incforsyn = 0; 1498 uint32_t tiwin; 1499 uint16_t nsegs; 1500 char *s; 1501 struct in_conninfo *inc; 1502 struct mbuf *mfree; 1503 struct tcpopt to; 1504 int tfo_syn; 1505 u_int maxseg; 1506 1507 #ifdef TCPDEBUG 1508 /* 1509 * The size of tcp_saveipgen must be the size of the max ip header, 1510 * now IPv6. 1511 */ 1512 u_char tcp_saveipgen[IP6_HDR_LEN]; 1513 struct tcphdr tcp_savetcp; 1514 short ostate = 0; 1515 #endif 1516 thflags = th->th_flags; 1517 inc = &tp->t_inpcb->inp_inc; 1518 tp->sackhint.last_sack_ack = 0; 1519 sack_changed = 0; 1520 nsegs = max(1, m->m_pkthdr.lro_nsegs); 1521 1522 NET_EPOCH_ASSERT(); 1523 INP_WLOCK_ASSERT(tp->t_inpcb); 1524 KASSERT(tp->t_state > TCPS_LISTEN, ("%s: TCPS_LISTEN", 1525 __func__)); 1526 KASSERT(tp->t_state != TCPS_TIME_WAIT, ("%s: TCPS_TIME_WAIT", 1527 __func__)); 1528 1529 #ifdef TCPPCAP 1530 /* Save segment, if requested. */ 1531 tcp_pcap_add(th, m, &(tp->t_inpkts)); 1532 #endif 1533 TCP_LOG_EVENT(tp, th, &so->so_rcv, &so->so_snd, TCP_LOG_IN, 0, 1534 tlen, NULL, true); 1535 1536 if ((thflags & TH_SYN) && (thflags & TH_FIN) && V_drop_synfin) { 1537 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1538 log(LOG_DEBUG, "%s; %s: " 1539 "SYN|FIN segment ignored (based on " 1540 "sysctl setting)\n", s, __func__); 1541 free(s, M_TCPLOG); 1542 } 1543 goto drop; 1544 } 1545 1546 /* 1547 * If a segment with the ACK-bit set arrives in the SYN-SENT state 1548 * check SEQ.ACK first. 1549 */ 1550 if ((tp->t_state == TCPS_SYN_SENT) && (thflags & TH_ACK) && 1551 (SEQ_LEQ(th->th_ack, tp->iss) || SEQ_GT(th->th_ack, tp->snd_max))) { 1552 rstreason = BANDLIM_UNLIMITED; 1553 goto dropwithreset; 1554 } 1555 1556 /* 1557 * Segment received on connection. 1558 * Reset idle time and keep-alive timer. 1559 * XXX: This should be done after segment 1560 * validation to ignore broken/spoofed segs. 1561 */ 1562 tp->t_rcvtime = ticks; 1563 1564 /* 1565 * Scale up the window into a 32-bit value. 1566 * For the SYN_SENT state the scale is zero. 1567 */ 1568 tiwin = th->th_win << tp->snd_scale; 1569 #ifdef STATS 1570 stats_voi_update_abs_ulong(tp->t_stats, VOI_TCP_FRWIN, tiwin); 1571 #endif 1572 1573 /* 1574 * TCP ECN processing. 1575 */ 1576 if (tp->t_flags2 & TF2_ECN_PERMIT) { 1577 if (thflags & TH_CWR) { 1578 tp->t_flags2 &= ~TF2_ECN_SND_ECE; 1579 tp->t_flags |= TF_ACKNOW; 1580 } 1581 switch (iptos & IPTOS_ECN_MASK) { 1582 case IPTOS_ECN_CE: 1583 tp->t_flags2 |= TF2_ECN_SND_ECE; 1584 TCPSTAT_INC(tcps_ecn_ce); 1585 break; 1586 case IPTOS_ECN_ECT0: 1587 TCPSTAT_INC(tcps_ecn_ect0); 1588 break; 1589 case IPTOS_ECN_ECT1: 1590 TCPSTAT_INC(tcps_ecn_ect1); 1591 break; 1592 } 1593 1594 /* Process a packet differently from RFC3168. */ 1595 cc_ecnpkt_handler(tp, th, iptos); 1596 1597 /* Congestion experienced. */ 1598 if (thflags & TH_ECE) { 1599 cc_cong_signal(tp, th, CC_ECN); 1600 } 1601 } 1602 1603 /* 1604 * Parse options on any incoming segment. 1605 */ 1606 tcp_dooptions(&to, (u_char *)(th + 1), 1607 (th->th_off << 2) - sizeof(struct tcphdr), 1608 (thflags & TH_SYN) ? TO_SYN : 0); 1609 1610 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 1611 if ((tp->t_flags & TF_SIGNATURE) != 0 && 1612 (to.to_flags & TOF_SIGNATURE) == 0) { 1613 TCPSTAT_INC(tcps_sig_err_sigopt); 1614 /* XXX: should drop? */ 1615 } 1616 #endif 1617 /* 1618 * If echoed timestamp is later than the current time, 1619 * fall back to non RFC1323 RTT calculation. Normalize 1620 * timestamp if syncookies were used when this connection 1621 * was established. 1622 */ 1623 if ((to.to_flags & TOF_TS) && (to.to_tsecr != 0)) { 1624 to.to_tsecr -= tp->ts_offset; 1625 if (TSTMP_GT(to.to_tsecr, tcp_ts_getticks())) 1626 to.to_tsecr = 0; 1627 else if (tp->t_flags & TF_PREVVALID && 1628 tp->t_badrxtwin != 0 && SEQ_LT(to.to_tsecr, tp->t_badrxtwin)) 1629 cc_cong_signal(tp, th, CC_RTO_ERR); 1630 } 1631 /* 1632 * Process options only when we get SYN/ACK back. The SYN case 1633 * for incoming connections is handled in tcp_syncache. 1634 * According to RFC1323 the window field in a SYN (i.e., a <SYN> 1635 * or <SYN,ACK>) segment itself is never scaled. 1636 * XXX this is traditional behavior, may need to be cleaned up. 1637 */ 1638 if (tp->t_state == TCPS_SYN_SENT && (thflags & TH_SYN)) { 1639 /* Handle parallel SYN for ECN */ 1640 if (!(thflags & TH_ACK) && 1641 ((thflags & (TH_CWR | TH_ECE)) == (TH_CWR | TH_ECE)) && 1642 ((V_tcp_do_ecn == 1) || (V_tcp_do_ecn == 2))) { 1643 tp->t_flags2 |= TF2_ECN_PERMIT; 1644 tp->t_flags2 |= TF2_ECN_SND_ECE; 1645 TCPSTAT_INC(tcps_ecn_shs); 1646 } 1647 if ((to.to_flags & TOF_SCALE) && 1648 (tp->t_flags & TF_REQ_SCALE) && 1649 !(tp->t_flags & TF_NOOPT)) { 1650 tp->t_flags |= TF_RCVD_SCALE; 1651 tp->snd_scale = to.to_wscale; 1652 } else 1653 tp->t_flags &= ~TF_REQ_SCALE; 1654 /* 1655 * Initial send window. It will be updated with 1656 * the next incoming segment to the scaled value. 1657 */ 1658 tp->snd_wnd = th->th_win; 1659 if ((to.to_flags & TOF_TS) && 1660 (tp->t_flags & TF_REQ_TSTMP) && 1661 !(tp->t_flags & TF_NOOPT)) { 1662 tp->t_flags |= TF_RCVD_TSTMP; 1663 tp->ts_recent = to.to_tsval; 1664 tp->ts_recent_age = tcp_ts_getticks(); 1665 } else 1666 tp->t_flags &= ~TF_REQ_TSTMP; 1667 if (to.to_flags & TOF_MSS) 1668 tcp_mss(tp, to.to_mss); 1669 if ((tp->t_flags & TF_SACK_PERMIT) && 1670 (!(to.to_flags & TOF_SACKPERM) || 1671 (tp->t_flags & TF_NOOPT))) 1672 tp->t_flags &= ~TF_SACK_PERMIT; 1673 if (IS_FASTOPEN(tp->t_flags)) { 1674 if ((to.to_flags & TOF_FASTOPEN) && 1675 !(tp->t_flags & TF_NOOPT)) { 1676 uint16_t mss; 1677 1678 if (to.to_flags & TOF_MSS) 1679 mss = to.to_mss; 1680 else 1681 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) 1682 mss = TCP6_MSS; 1683 else 1684 mss = TCP_MSS; 1685 tcp_fastopen_update_cache(tp, mss, 1686 to.to_tfo_len, to.to_tfo_cookie); 1687 } else 1688 tcp_fastopen_disable_path(tp); 1689 } 1690 } 1691 1692 /* 1693 * If timestamps were negotiated during SYN/ACK and a 1694 * segment without a timestamp is received, silently drop 1695 * the segment, unless it is a RST segment or missing timestamps are 1696 * tolerated. 1697 * See section 3.2 of RFC 7323. 1698 */ 1699 if ((tp->t_flags & TF_RCVD_TSTMP) && !(to.to_flags & TOF_TS)) { 1700 if (((thflags & TH_RST) != 0) || V_tcp_tolerate_missing_ts) { 1701 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1702 log(LOG_DEBUG, "%s; %s: Timestamp missing, " 1703 "segment processed normally\n", 1704 s, __func__); 1705 free(s, M_TCPLOG); 1706 } 1707 } else { 1708 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1709 log(LOG_DEBUG, "%s; %s: Timestamp missing, " 1710 "segment silently dropped\n", s, __func__); 1711 free(s, M_TCPLOG); 1712 } 1713 goto drop; 1714 } 1715 } 1716 /* 1717 * If timestamps were not negotiated during SYN/ACK and a 1718 * segment with a timestamp is received, ignore the 1719 * timestamp and process the packet normally. 1720 * See section 3.2 of RFC 7323. 1721 */ 1722 if (!(tp->t_flags & TF_RCVD_TSTMP) && (to.to_flags & TOF_TS)) { 1723 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1724 log(LOG_DEBUG, "%s; %s: Timestamp not expected, " 1725 "segment processed normally\n", s, __func__); 1726 free(s, M_TCPLOG); 1727 } 1728 } 1729 1730 /* 1731 * Header prediction: check for the two common cases 1732 * of a uni-directional data xfer. If the packet has 1733 * no control flags, is in-sequence, the window didn't 1734 * change and we're not retransmitting, it's a 1735 * candidate. If the length is zero and the ack moved 1736 * forward, we're the sender side of the xfer. Just 1737 * free the data acked & wake any higher level process 1738 * that was blocked waiting for space. If the length 1739 * is non-zero and the ack didn't move, we're the 1740 * receiver side. If we're getting packets in-order 1741 * (the reassembly queue is empty), add the data to 1742 * the socket buffer and note that we need a delayed ack. 1743 * Make sure that the hidden state-flags are also off. 1744 * Since we check for TCPS_ESTABLISHED first, it can only 1745 * be TH_NEEDSYN. 1746 */ 1747 if (tp->t_state == TCPS_ESTABLISHED && 1748 th->th_seq == tp->rcv_nxt && 1749 (thflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK && 1750 tp->snd_nxt == tp->snd_max && 1751 tiwin && tiwin == tp->snd_wnd && 1752 ((tp->t_flags & (TF_NEEDSYN|TF_NEEDFIN)) == 0) && 1753 SEGQ_EMPTY(tp) && 1754 ((to.to_flags & TOF_TS) == 0 || 1755 TSTMP_GEQ(to.to_tsval, tp->ts_recent)) ) { 1756 /* 1757 * If last ACK falls within this segment's sequence numbers, 1758 * record the timestamp. 1759 * NOTE that the test is modified according to the latest 1760 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 1761 */ 1762 if ((to.to_flags & TOF_TS) != 0 && 1763 SEQ_LEQ(th->th_seq, tp->last_ack_sent)) { 1764 tp->ts_recent_age = tcp_ts_getticks(); 1765 tp->ts_recent = to.to_tsval; 1766 } 1767 1768 if (tlen == 0) { 1769 if (SEQ_GT(th->th_ack, tp->snd_una) && 1770 SEQ_LEQ(th->th_ack, tp->snd_max) && 1771 !IN_RECOVERY(tp->t_flags) && 1772 (to.to_flags & TOF_SACK) == 0 && 1773 TAILQ_EMPTY(&tp->snd_holes)) { 1774 /* 1775 * This is a pure ack for outstanding data. 1776 */ 1777 TCPSTAT_INC(tcps_predack); 1778 1779 /* 1780 * "bad retransmit" recovery without timestamps. 1781 */ 1782 if ((to.to_flags & TOF_TS) == 0 && 1783 tp->t_rxtshift == 1 && 1784 tp->t_flags & TF_PREVVALID && 1785 (int)(ticks - tp->t_badrxtwin) < 0) { 1786 cc_cong_signal(tp, th, CC_RTO_ERR); 1787 } 1788 1789 /* 1790 * Recalculate the transmit timer / rtt. 1791 * 1792 * Some boxes send broken timestamp replies 1793 * during the SYN+ACK phase, ignore 1794 * timestamps of 0 or we could calculate a 1795 * huge RTT and blow up the retransmit timer. 1796 */ 1797 if ((to.to_flags & TOF_TS) != 0 && 1798 to.to_tsecr) { 1799 uint32_t t; 1800 1801 t = tcp_ts_getticks() - to.to_tsecr; 1802 if (!tp->t_rttlow || tp->t_rttlow > t) 1803 tp->t_rttlow = t; 1804 tcp_xmit_timer(tp, 1805 TCP_TS_TO_TICKS(t) + 1); 1806 } else if (tp->t_rtttime && 1807 SEQ_GT(th->th_ack, tp->t_rtseq)) { 1808 if (!tp->t_rttlow || 1809 tp->t_rttlow > ticks - tp->t_rtttime) 1810 tp->t_rttlow = ticks - tp->t_rtttime; 1811 tcp_xmit_timer(tp, 1812 ticks - tp->t_rtttime); 1813 } 1814 acked = BYTES_THIS_ACK(tp, th); 1815 1816 #ifdef TCP_HHOOK 1817 /* Run HHOOK_TCP_ESTABLISHED_IN helper hooks. */ 1818 hhook_run_tcp_est_in(tp, th, &to); 1819 #endif 1820 1821 TCPSTAT_ADD(tcps_rcvackpack, nsegs); 1822 TCPSTAT_ADD(tcps_rcvackbyte, acked); 1823 sbdrop(&so->so_snd, acked); 1824 if (SEQ_GT(tp->snd_una, tp->snd_recover) && 1825 SEQ_LEQ(th->th_ack, tp->snd_recover)) 1826 tp->snd_recover = th->th_ack - 1; 1827 1828 /* 1829 * Let the congestion control algorithm update 1830 * congestion control related information. This 1831 * typically means increasing the congestion 1832 * window. 1833 */ 1834 cc_ack_received(tp, th, nsegs, CC_ACK); 1835 1836 tp->snd_una = th->th_ack; 1837 /* 1838 * Pull snd_wl2 up to prevent seq wrap relative 1839 * to th_ack. 1840 */ 1841 tp->snd_wl2 = th->th_ack; 1842 tp->t_dupacks = 0; 1843 m_freem(m); 1844 1845 /* 1846 * If all outstanding data are acked, stop 1847 * retransmit timer, otherwise restart timer 1848 * using current (possibly backed-off) value. 1849 * If process is waiting for space, 1850 * wakeup/selwakeup/signal. If data 1851 * are ready to send, let tcp_output 1852 * decide between more output or persist. 1853 */ 1854 #ifdef TCPDEBUG 1855 if (so->so_options & SO_DEBUG) 1856 tcp_trace(TA_INPUT, ostate, tp, 1857 (void *)tcp_saveipgen, 1858 &tcp_savetcp, 0); 1859 #endif 1860 TCP_PROBE3(debug__input, tp, th, m); 1861 if (tp->snd_una == tp->snd_max) 1862 tcp_timer_activate(tp, TT_REXMT, 0); 1863 else if (!tcp_timer_active(tp, TT_PERSIST)) 1864 tcp_timer_activate(tp, TT_REXMT, 1865 tp->t_rxtcur); 1866 tp->t_flags |= TF_WAKESOW; 1867 if (sbavail(&so->so_snd)) 1868 (void) tp->t_fb->tfb_tcp_output(tp); 1869 goto check_delack; 1870 } 1871 } else if (th->th_ack == tp->snd_una && 1872 tlen <= sbspace(&so->so_rcv)) { 1873 int newsize = 0; /* automatic sockbuf scaling */ 1874 1875 /* 1876 * This is a pure, in-sequence data packet with 1877 * nothing on the reassembly queue and we have enough 1878 * buffer space to take it. 1879 */ 1880 /* Clean receiver SACK report if present */ 1881 if ((tp->t_flags & TF_SACK_PERMIT) && tp->rcv_numsacks) 1882 tcp_clean_sackreport(tp); 1883 TCPSTAT_INC(tcps_preddat); 1884 tp->rcv_nxt += tlen; 1885 if (tlen && 1886 ((tp->t_flags2 & TF2_FBYTES_COMPLETE) == 0) && 1887 (tp->t_fbyte_in == 0)) { 1888 tp->t_fbyte_in = ticks; 1889 if (tp->t_fbyte_in == 0) 1890 tp->t_fbyte_in = 1; 1891 if (tp->t_fbyte_out && tp->t_fbyte_in) 1892 tp->t_flags2 |= TF2_FBYTES_COMPLETE; 1893 } 1894 /* 1895 * Pull snd_wl1 up to prevent seq wrap relative to 1896 * th_seq. 1897 */ 1898 tp->snd_wl1 = th->th_seq; 1899 /* 1900 * Pull rcv_up up to prevent seq wrap relative to 1901 * rcv_nxt. 1902 */ 1903 tp->rcv_up = tp->rcv_nxt; 1904 TCPSTAT_ADD(tcps_rcvpack, nsegs); 1905 TCPSTAT_ADD(tcps_rcvbyte, tlen); 1906 #ifdef TCPDEBUG 1907 if (so->so_options & SO_DEBUG) 1908 tcp_trace(TA_INPUT, ostate, tp, 1909 (void *)tcp_saveipgen, &tcp_savetcp, 0); 1910 #endif 1911 TCP_PROBE3(debug__input, tp, th, m); 1912 1913 newsize = tcp_autorcvbuf(m, th, so, tp, tlen); 1914 1915 /* Add data to socket buffer. */ 1916 SOCKBUF_LOCK(&so->so_rcv); 1917 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 1918 m_freem(m); 1919 } else { 1920 /* 1921 * Set new socket buffer size. 1922 * Give up when limit is reached. 1923 */ 1924 if (newsize) 1925 if (!sbreserve_locked(&so->so_rcv, 1926 newsize, so, NULL)) 1927 so->so_rcv.sb_flags &= ~SB_AUTOSIZE; 1928 m_adj(m, drop_hdrlen); /* delayed header drop */ 1929 sbappendstream_locked(&so->so_rcv, m, 0); 1930 } 1931 SOCKBUF_UNLOCK(&so->so_rcv); 1932 tp->t_flags |= TF_WAKESOR; 1933 if (DELAY_ACK(tp, tlen)) { 1934 tp->t_flags |= TF_DELACK; 1935 } else { 1936 tp->t_flags |= TF_ACKNOW; 1937 tp->t_fb->tfb_tcp_output(tp); 1938 } 1939 goto check_delack; 1940 } 1941 } 1942 1943 /* 1944 * Calculate amount of space in receive window, 1945 * and then do TCP input processing. 1946 * Receive window is amount of space in rcv queue, 1947 * but not less than advertised window. 1948 */ 1949 win = sbspace(&so->so_rcv); 1950 if (win < 0) 1951 win = 0; 1952 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 1953 1954 switch (tp->t_state) { 1955 /* 1956 * If the state is SYN_RECEIVED: 1957 * if seg contains an ACK, but not for our SYN/ACK, send a RST. 1958 */ 1959 case TCPS_SYN_RECEIVED: 1960 if ((thflags & TH_ACK) && 1961 (SEQ_LEQ(th->th_ack, tp->snd_una) || 1962 SEQ_GT(th->th_ack, tp->snd_max))) { 1963 rstreason = BANDLIM_RST_OPENPORT; 1964 goto dropwithreset; 1965 } 1966 if (IS_FASTOPEN(tp->t_flags)) { 1967 /* 1968 * When a TFO connection is in SYN_RECEIVED, the 1969 * only valid packets are the initial SYN, a 1970 * retransmit/copy of the initial SYN (possibly with 1971 * a subset of the original data), a valid ACK, a 1972 * FIN, or a RST. 1973 */ 1974 if ((thflags & (TH_SYN|TH_ACK)) == (TH_SYN|TH_ACK)) { 1975 rstreason = BANDLIM_RST_OPENPORT; 1976 goto dropwithreset; 1977 } else if (thflags & TH_SYN) { 1978 /* non-initial SYN is ignored */ 1979 if ((tcp_timer_active(tp, TT_DELACK) || 1980 tcp_timer_active(tp, TT_REXMT))) 1981 goto drop; 1982 } else if (!(thflags & (TH_ACK|TH_FIN|TH_RST))) { 1983 goto drop; 1984 } 1985 } 1986 break; 1987 1988 /* 1989 * If the state is SYN_SENT: 1990 * if seg contains a RST with valid ACK (SEQ.ACK has already 1991 * been verified), then drop the connection. 1992 * if seg contains a RST without an ACK, drop the seg. 1993 * if seg does not contain SYN, then drop the seg. 1994 * Otherwise this is an acceptable SYN segment 1995 * initialize tp->rcv_nxt and tp->irs 1996 * if seg contains ack then advance tp->snd_una 1997 * if seg contains an ECE and ECN support is enabled, the stream 1998 * is ECN capable. 1999 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 2000 * arrange for segment to be acked (eventually) 2001 * continue processing rest of data/controls, beginning with URG 2002 */ 2003 case TCPS_SYN_SENT: 2004 if ((thflags & (TH_ACK|TH_RST)) == (TH_ACK|TH_RST)) { 2005 TCP_PROBE5(connect__refused, NULL, tp, 2006 m, tp, th); 2007 tp = tcp_drop(tp, ECONNREFUSED); 2008 } 2009 if (thflags & TH_RST) 2010 goto drop; 2011 if (!(thflags & TH_SYN)) 2012 goto drop; 2013 2014 tp->irs = th->th_seq; 2015 tcp_rcvseqinit(tp); 2016 if (thflags & TH_ACK) { 2017 int tfo_partial_ack = 0; 2018 2019 TCPSTAT_INC(tcps_connects); 2020 soisconnected(so); 2021 #ifdef MAC 2022 mac_socketpeer_set_from_mbuf(m, so); 2023 #endif 2024 /* Do window scaling on this connection? */ 2025 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2026 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2027 tp->rcv_scale = tp->request_r_scale; 2028 } 2029 tp->rcv_adv += min(tp->rcv_wnd, 2030 TCP_MAXWIN << tp->rcv_scale); 2031 tp->snd_una++; /* SYN is acked */ 2032 /* 2033 * If not all the data that was sent in the TFO SYN 2034 * has been acked, resend the remainder right away. 2035 */ 2036 if (IS_FASTOPEN(tp->t_flags) && 2037 (tp->snd_una != tp->snd_max)) { 2038 tp->snd_nxt = th->th_ack; 2039 tfo_partial_ack = 1; 2040 } 2041 /* 2042 * If there's data, delay ACK; if there's also a FIN 2043 * ACKNOW will be turned on later. 2044 */ 2045 if (DELAY_ACK(tp, tlen) && tlen != 0 && !tfo_partial_ack) 2046 tcp_timer_activate(tp, TT_DELACK, 2047 tcp_delacktime); 2048 else 2049 tp->t_flags |= TF_ACKNOW; 2050 2051 if (((thflags & (TH_CWR | TH_ECE)) == TH_ECE) && 2052 (V_tcp_do_ecn == 1)) { 2053 tp->t_flags2 |= TF2_ECN_PERMIT; 2054 TCPSTAT_INC(tcps_ecn_shs); 2055 } 2056 2057 /* 2058 * Received <SYN,ACK> in SYN_SENT[*] state. 2059 * Transitions: 2060 * SYN_SENT --> ESTABLISHED 2061 * SYN_SENT* --> FIN_WAIT_1 2062 */ 2063 tp->t_starttime = ticks; 2064 if (tp->t_flags & TF_NEEDFIN) { 2065 tcp_state_change(tp, TCPS_FIN_WAIT_1); 2066 tp->t_flags &= ~TF_NEEDFIN; 2067 thflags &= ~TH_SYN; 2068 } else { 2069 tcp_state_change(tp, TCPS_ESTABLISHED); 2070 TCP_PROBE5(connect__established, NULL, tp, 2071 m, tp, th); 2072 cc_conn_init(tp); 2073 tcp_timer_activate(tp, TT_KEEP, 2074 TP_KEEPIDLE(tp)); 2075 } 2076 } else { 2077 /* 2078 * Received initial SYN in SYN-SENT[*] state => 2079 * simultaneous open. 2080 * If it succeeds, connection is * half-synchronized. 2081 * Otherwise, do 3-way handshake: 2082 * SYN-SENT -> SYN-RECEIVED 2083 * SYN-SENT* -> SYN-RECEIVED* 2084 */ 2085 tp->t_flags |= (TF_ACKNOW | TF_NEEDSYN); 2086 tcp_timer_activate(tp, TT_REXMT, 0); 2087 tcp_state_change(tp, TCPS_SYN_RECEIVED); 2088 } 2089 2090 INP_WLOCK_ASSERT(tp->t_inpcb); 2091 2092 /* 2093 * Advance th->th_seq to correspond to first data byte. 2094 * If data, trim to stay within window, 2095 * dropping FIN if necessary. 2096 */ 2097 th->th_seq++; 2098 if (tlen > tp->rcv_wnd) { 2099 todrop = tlen - tp->rcv_wnd; 2100 m_adj(m, -todrop); 2101 tlen = tp->rcv_wnd; 2102 thflags &= ~TH_FIN; 2103 TCPSTAT_INC(tcps_rcvpackafterwin); 2104 TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); 2105 } 2106 tp->snd_wl1 = th->th_seq - 1; 2107 tp->rcv_up = th->th_seq; 2108 /* 2109 * Client side of transaction: already sent SYN and data. 2110 * If the remote host used T/TCP to validate the SYN, 2111 * our data will be ACK'd; if so, enter normal data segment 2112 * processing in the middle of step 5, ack processing. 2113 * Otherwise, goto step 6. 2114 */ 2115 if (thflags & TH_ACK) 2116 goto process_ACK; 2117 2118 goto step6; 2119 2120 /* 2121 * If the state is LAST_ACK or CLOSING or TIME_WAIT: 2122 * do normal processing. 2123 * 2124 * NB: Leftover from RFC1644 T/TCP. Cases to be reused later. 2125 */ 2126 case TCPS_LAST_ACK: 2127 case TCPS_CLOSING: 2128 break; /* continue normal processing */ 2129 } 2130 2131 /* 2132 * States other than LISTEN or SYN_SENT. 2133 * First check the RST flag and sequence number since reset segments 2134 * are exempt from the timestamp and connection count tests. This 2135 * fixes a bug introduced by the Stevens, vol. 2, p. 960 bugfix 2136 * below which allowed reset segments in half the sequence space 2137 * to fall though and be processed (which gives forged reset 2138 * segments with a random sequence number a 50 percent chance of 2139 * killing a connection). 2140 * Then check timestamp, if present. 2141 * Then check the connection count, if present. 2142 * Then check that at least some bytes of segment are within 2143 * receive window. If segment begins before rcv_nxt, 2144 * drop leading data (and SYN); if nothing left, just ack. 2145 */ 2146 if (thflags & TH_RST) { 2147 /* 2148 * RFC5961 Section 3.2 2149 * 2150 * - RST drops connection only if SEG.SEQ == RCV.NXT. 2151 * - If RST is in window, we send challenge ACK. 2152 * 2153 * Note: to take into account delayed ACKs, we should 2154 * test against last_ack_sent instead of rcv_nxt. 2155 * Note 2: we handle special case of closed window, not 2156 * covered by the RFC. 2157 */ 2158 if ((SEQ_GEQ(th->th_seq, tp->last_ack_sent) && 2159 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) || 2160 (tp->rcv_wnd == 0 && tp->last_ack_sent == th->th_seq)) { 2161 KASSERT(tp->t_state != TCPS_SYN_SENT, 2162 ("%s: TH_RST for TCPS_SYN_SENT th %p tp %p", 2163 __func__, th, tp)); 2164 2165 if (V_tcp_insecure_rst || 2166 tp->last_ack_sent == th->th_seq) { 2167 TCPSTAT_INC(tcps_drops); 2168 /* Drop the connection. */ 2169 switch (tp->t_state) { 2170 case TCPS_SYN_RECEIVED: 2171 so->so_error = ECONNREFUSED; 2172 goto close; 2173 case TCPS_ESTABLISHED: 2174 case TCPS_FIN_WAIT_1: 2175 case TCPS_FIN_WAIT_2: 2176 case TCPS_CLOSE_WAIT: 2177 case TCPS_CLOSING: 2178 case TCPS_LAST_ACK: 2179 so->so_error = ECONNRESET; 2180 close: 2181 /* FALLTHROUGH */ 2182 default: 2183 tp = tcp_close(tp); 2184 } 2185 } else { 2186 TCPSTAT_INC(tcps_badrst); 2187 /* Send challenge ACK. */ 2188 tcp_respond(tp, mtod(m, void *), th, m, 2189 tp->rcv_nxt, tp->snd_nxt, TH_ACK); 2190 tp->last_ack_sent = tp->rcv_nxt; 2191 m = NULL; 2192 } 2193 } 2194 goto drop; 2195 } 2196 2197 /* 2198 * RFC5961 Section 4.2 2199 * Send challenge ACK for any SYN in synchronized state. 2200 */ 2201 if ((thflags & TH_SYN) && tp->t_state != TCPS_SYN_SENT && 2202 tp->t_state != TCPS_SYN_RECEIVED) { 2203 TCPSTAT_INC(tcps_badsyn); 2204 if (V_tcp_insecure_syn && 2205 SEQ_GEQ(th->th_seq, tp->last_ack_sent) && 2206 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) { 2207 tp = tcp_drop(tp, ECONNRESET); 2208 rstreason = BANDLIM_UNLIMITED; 2209 } else { 2210 /* Send challenge ACK. */ 2211 tcp_respond(tp, mtod(m, void *), th, m, tp->rcv_nxt, 2212 tp->snd_nxt, TH_ACK); 2213 tp->last_ack_sent = tp->rcv_nxt; 2214 m = NULL; 2215 } 2216 goto drop; 2217 } 2218 2219 /* 2220 * RFC 1323 PAWS: If we have a timestamp reply on this segment 2221 * and it's less than ts_recent, drop it. 2222 */ 2223 if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent && 2224 TSTMP_LT(to.to_tsval, tp->ts_recent)) { 2225 /* Check to see if ts_recent is over 24 days old. */ 2226 if (tcp_ts_getticks() - tp->ts_recent_age > TCP_PAWS_IDLE) { 2227 /* 2228 * Invalidate ts_recent. If this segment updates 2229 * ts_recent, the age will be reset later and ts_recent 2230 * will get a valid value. If it does not, setting 2231 * ts_recent to zero will at least satisfy the 2232 * requirement that zero be placed in the timestamp 2233 * echo reply when ts_recent isn't valid. The 2234 * age isn't reset until we get a valid ts_recent 2235 * because we don't want out-of-order segments to be 2236 * dropped when ts_recent is old. 2237 */ 2238 tp->ts_recent = 0; 2239 } else { 2240 TCPSTAT_INC(tcps_rcvduppack); 2241 TCPSTAT_ADD(tcps_rcvdupbyte, tlen); 2242 TCPSTAT_INC(tcps_pawsdrop); 2243 if (tlen) 2244 goto dropafterack; 2245 goto drop; 2246 } 2247 } 2248 2249 /* 2250 * In the SYN-RECEIVED state, validate that the packet belongs to 2251 * this connection before trimming the data to fit the receive 2252 * window. Check the sequence number versus IRS since we know 2253 * the sequence numbers haven't wrapped. This is a partial fix 2254 * for the "LAND" DoS attack. 2255 */ 2256 if (tp->t_state == TCPS_SYN_RECEIVED && SEQ_LT(th->th_seq, tp->irs)) { 2257 rstreason = BANDLIM_RST_OPENPORT; 2258 goto dropwithreset; 2259 } 2260 2261 todrop = tp->rcv_nxt - th->th_seq; 2262 if (todrop > 0) { 2263 if (thflags & TH_SYN) { 2264 thflags &= ~TH_SYN; 2265 th->th_seq++; 2266 if (th->th_urp > 1) 2267 th->th_urp--; 2268 else 2269 thflags &= ~TH_URG; 2270 todrop--; 2271 } 2272 /* 2273 * Following if statement from Stevens, vol. 2, p. 960. 2274 */ 2275 if (todrop > tlen 2276 || (todrop == tlen && (thflags & TH_FIN) == 0)) { 2277 /* 2278 * Any valid FIN must be to the left of the window. 2279 * At this point the FIN must be a duplicate or out 2280 * of sequence; drop it. 2281 */ 2282 thflags &= ~TH_FIN; 2283 2284 /* 2285 * Send an ACK to resynchronize and drop any data. 2286 * But keep on processing for RST or ACK. 2287 */ 2288 tp->t_flags |= TF_ACKNOW; 2289 todrop = tlen; 2290 TCPSTAT_INC(tcps_rcvduppack); 2291 TCPSTAT_ADD(tcps_rcvdupbyte, todrop); 2292 } else { 2293 TCPSTAT_INC(tcps_rcvpartduppack); 2294 TCPSTAT_ADD(tcps_rcvpartdupbyte, todrop); 2295 } 2296 /* 2297 * DSACK - add SACK block for dropped range 2298 */ 2299 if ((todrop > 0) && (tp->t_flags & TF_SACK_PERMIT)) { 2300 tcp_update_sack_list(tp, th->th_seq, 2301 th->th_seq + todrop); 2302 /* 2303 * ACK now, as the next in-sequence segment 2304 * will clear the DSACK block again 2305 */ 2306 tp->t_flags |= TF_ACKNOW; 2307 } 2308 drop_hdrlen += todrop; /* drop from the top afterwards */ 2309 th->th_seq += todrop; 2310 tlen -= todrop; 2311 if (th->th_urp > todrop) 2312 th->th_urp -= todrop; 2313 else { 2314 thflags &= ~TH_URG; 2315 th->th_urp = 0; 2316 } 2317 } 2318 2319 /* 2320 * If new data are received on a connection after the 2321 * user processes are gone, then RST the other end. 2322 */ 2323 if ((so->so_state & SS_NOFDREF) && 2324 tp->t_state > TCPS_CLOSE_WAIT && tlen) { 2325 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 2326 log(LOG_DEBUG, "%s; %s: %s: Received %d bytes of data " 2327 "after socket was closed, " 2328 "sending RST and removing tcpcb\n", 2329 s, __func__, tcpstates[tp->t_state], tlen); 2330 free(s, M_TCPLOG); 2331 } 2332 tp = tcp_close(tp); 2333 TCPSTAT_INC(tcps_rcvafterclose); 2334 rstreason = BANDLIM_UNLIMITED; 2335 goto dropwithreset; 2336 } 2337 2338 /* 2339 * If segment ends after window, drop trailing data 2340 * (and PUSH and FIN); if nothing left, just ACK. 2341 */ 2342 todrop = (th->th_seq + tlen) - (tp->rcv_nxt + tp->rcv_wnd); 2343 if (todrop > 0) { 2344 TCPSTAT_INC(tcps_rcvpackafterwin); 2345 if (todrop >= tlen) { 2346 TCPSTAT_ADD(tcps_rcvbyteafterwin, tlen); 2347 /* 2348 * If window is closed can only take segments at 2349 * window edge, and have to drop data and PUSH from 2350 * incoming segments. Continue processing, but 2351 * remember to ack. Otherwise, drop segment 2352 * and ack. 2353 */ 2354 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 2355 tp->t_flags |= TF_ACKNOW; 2356 TCPSTAT_INC(tcps_rcvwinprobe); 2357 } else 2358 goto dropafterack; 2359 } else 2360 TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); 2361 m_adj(m, -todrop); 2362 tlen -= todrop; 2363 thflags &= ~(TH_PUSH|TH_FIN); 2364 } 2365 2366 /* 2367 * If last ACK falls within this segment's sequence numbers, 2368 * record its timestamp. 2369 * NOTE: 2370 * 1) That the test incorporates suggestions from the latest 2371 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 2372 * 2) That updating only on newer timestamps interferes with 2373 * our earlier PAWS tests, so this check should be solely 2374 * predicated on the sequence space of this segment. 2375 * 3) That we modify the segment boundary check to be 2376 * Last.ACK.Sent <= SEG.SEQ + SEG.Len 2377 * instead of RFC1323's 2378 * Last.ACK.Sent < SEG.SEQ + SEG.Len, 2379 * This modified check allows us to overcome RFC1323's 2380 * limitations as described in Stevens TCP/IP Illustrated 2381 * Vol. 2 p.869. In such cases, we can still calculate the 2382 * RTT correctly when RCV.NXT == Last.ACK.Sent. 2383 */ 2384 if ((to.to_flags & TOF_TS) != 0 && 2385 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 2386 SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen + 2387 ((thflags & (TH_SYN|TH_FIN)) != 0))) { 2388 tp->ts_recent_age = tcp_ts_getticks(); 2389 tp->ts_recent = to.to_tsval; 2390 } 2391 2392 /* 2393 * If the ACK bit is off: if in SYN-RECEIVED state or SENDSYN 2394 * flag is on (half-synchronized state), then queue data for 2395 * later processing; else drop segment and return. 2396 */ 2397 if ((thflags & TH_ACK) == 0) { 2398 if (tp->t_state == TCPS_SYN_RECEIVED || 2399 (tp->t_flags & TF_NEEDSYN)) { 2400 if (tp->t_state == TCPS_SYN_RECEIVED && 2401 IS_FASTOPEN(tp->t_flags)) { 2402 tp->snd_wnd = tiwin; 2403 cc_conn_init(tp); 2404 } 2405 goto step6; 2406 } else if (tp->t_flags & TF_ACKNOW) 2407 goto dropafterack; 2408 else 2409 goto drop; 2410 } 2411 2412 /* 2413 * Ack processing. 2414 */ 2415 switch (tp->t_state) { 2416 /* 2417 * In SYN_RECEIVED state, the ack ACKs our SYN, so enter 2418 * ESTABLISHED state and continue processing. 2419 * The ACK was checked above. 2420 */ 2421 case TCPS_SYN_RECEIVED: 2422 2423 TCPSTAT_INC(tcps_connects); 2424 soisconnected(so); 2425 /* Do window scaling? */ 2426 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2427 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2428 tp->rcv_scale = tp->request_r_scale; 2429 } 2430 tp->snd_wnd = tiwin; 2431 /* 2432 * Make transitions: 2433 * SYN-RECEIVED -> ESTABLISHED 2434 * SYN-RECEIVED* -> FIN-WAIT-1 2435 */ 2436 tp->t_starttime = ticks; 2437 if (IS_FASTOPEN(tp->t_flags) && tp->t_tfo_pending) { 2438 tcp_fastopen_decrement_counter(tp->t_tfo_pending); 2439 tp->t_tfo_pending = NULL; 2440 } 2441 if (tp->t_flags & TF_NEEDFIN) { 2442 tcp_state_change(tp, TCPS_FIN_WAIT_1); 2443 tp->t_flags &= ~TF_NEEDFIN; 2444 } else { 2445 tcp_state_change(tp, TCPS_ESTABLISHED); 2446 TCP_PROBE5(accept__established, NULL, tp, 2447 m, tp, th); 2448 /* 2449 * TFO connections call cc_conn_init() during SYN 2450 * processing. Calling it again here for such 2451 * connections is not harmless as it would undo the 2452 * snd_cwnd reduction that occurs when a TFO SYN|ACK 2453 * is retransmitted. 2454 */ 2455 if (!IS_FASTOPEN(tp->t_flags)) 2456 cc_conn_init(tp); 2457 tcp_timer_activate(tp, TT_KEEP, TP_KEEPIDLE(tp)); 2458 } 2459 /* 2460 * Account for the ACK of our SYN prior to 2461 * regular ACK processing below, except for 2462 * simultaneous SYN, which is handled later. 2463 */ 2464 if (SEQ_GT(th->th_ack, tp->snd_una) && !(tp->t_flags & TF_NEEDSYN)) 2465 incforsyn = 1; 2466 /* 2467 * If segment contains data or ACK, will call tcp_reass() 2468 * later; if not, do so now to pass queued data to user. 2469 */ 2470 if (tlen == 0 && (thflags & TH_FIN) == 0) 2471 (void) tcp_reass(tp, (struct tcphdr *)0, NULL, 0, 2472 (struct mbuf *)0); 2473 tp->snd_wl1 = th->th_seq - 1; 2474 /* FALLTHROUGH */ 2475 2476 /* 2477 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 2478 * ACKs. If the ack is in the range 2479 * tp->snd_una < th->th_ack <= tp->snd_max 2480 * then advance tp->snd_una to th->th_ack and drop 2481 * data from the retransmission queue. If this ACK reflects 2482 * more up to date window information we update our window information. 2483 */ 2484 case TCPS_ESTABLISHED: 2485 case TCPS_FIN_WAIT_1: 2486 case TCPS_FIN_WAIT_2: 2487 case TCPS_CLOSE_WAIT: 2488 case TCPS_CLOSING: 2489 case TCPS_LAST_ACK: 2490 if (SEQ_GT(th->th_ack, tp->snd_max)) { 2491 TCPSTAT_INC(tcps_rcvacktoomuch); 2492 goto dropafterack; 2493 } 2494 if ((tp->t_flags & TF_SACK_PERMIT) && 2495 ((to.to_flags & TOF_SACK) || 2496 !TAILQ_EMPTY(&tp->snd_holes))) 2497 sack_changed = tcp_sack_doack(tp, &to, th->th_ack); 2498 else 2499 /* 2500 * Reset the value so that previous (valid) value 2501 * from the last ack with SACK doesn't get used. 2502 */ 2503 tp->sackhint.sacked_bytes = 0; 2504 2505 #ifdef TCP_HHOOK 2506 /* Run HHOOK_TCP_ESTABLISHED_IN helper hooks. */ 2507 hhook_run_tcp_est_in(tp, th, &to); 2508 #endif 2509 2510 if (SEQ_LEQ(th->th_ack, tp->snd_una)) { 2511 maxseg = tcp_maxseg(tp); 2512 if (tlen == 0 && 2513 (tiwin == tp->snd_wnd || 2514 (tp->t_flags & TF_SACK_PERMIT))) { 2515 /* 2516 * If this is the first time we've seen a 2517 * FIN from the remote, this is not a 2518 * duplicate and it needs to be processed 2519 * normally. This happens during a 2520 * simultaneous close. 2521 */ 2522 if ((thflags & TH_FIN) && 2523 (TCPS_HAVERCVDFIN(tp->t_state) == 0)) { 2524 tp->t_dupacks = 0; 2525 break; 2526 } 2527 TCPSTAT_INC(tcps_rcvdupack); 2528 /* 2529 * If we have outstanding data (other than 2530 * a window probe), this is a completely 2531 * duplicate ack (ie, window info didn't 2532 * change and FIN isn't set), 2533 * the ack is the biggest we've 2534 * seen and we've seen exactly our rexmt 2535 * threshold of them, assume a packet 2536 * has been dropped and retransmit it. 2537 * Kludge snd_nxt & the congestion 2538 * window so we send only this one 2539 * packet. 2540 * 2541 * We know we're losing at the current 2542 * window size so do congestion avoidance 2543 * (set ssthresh to half the current window 2544 * and pull our congestion window back to 2545 * the new ssthresh). 2546 * 2547 * Dup acks mean that packets have left the 2548 * network (they're now cached at the receiver) 2549 * so bump cwnd by the amount in the receiver 2550 * to keep a constant cwnd packets in the 2551 * network. 2552 * 2553 * When using TCP ECN, notify the peer that 2554 * we reduced the cwnd. 2555 */ 2556 /* 2557 * Following 2 kinds of acks should not affect 2558 * dupack counting: 2559 * 1) Old acks 2560 * 2) Acks with SACK but without any new SACK 2561 * information in them. These could result from 2562 * any anomaly in the network like a switch 2563 * duplicating packets or a possible DoS attack. 2564 */ 2565 if (th->th_ack != tp->snd_una || 2566 ((tp->t_flags & TF_SACK_PERMIT) && 2567 !sack_changed)) 2568 break; 2569 else if (!tcp_timer_active(tp, TT_REXMT)) 2570 tp->t_dupacks = 0; 2571 else if (++tp->t_dupacks > tcprexmtthresh || 2572 IN_FASTRECOVERY(tp->t_flags)) { 2573 cc_ack_received(tp, th, nsegs, 2574 CC_DUPACK); 2575 if (V_tcp_do_prr && 2576 IN_FASTRECOVERY(tp->t_flags) && 2577 (tp->t_flags & TF_SACK_PERMIT)) { 2578 int snd_cnt = 0, limit = 0; 2579 int del_data = 0, pipe = 0; 2580 /* 2581 * In a duplicate ACK del_data is only the 2582 * diff_in_sack. If no SACK is used del_data 2583 * will be 0. Pipe is the amount of data we 2584 * estimate to be in the network. 2585 */ 2586 del_data = tp->sackhint.delivered_data; 2587 if (V_tcp_do_rfc6675_pipe) 2588 pipe = tcp_compute_pipe(tp); 2589 else 2590 pipe = (tp->snd_nxt - tp->snd_fack) + 2591 tp->sackhint.sack_bytes_rexmit; 2592 tp->sackhint.prr_delivered += del_data; 2593 if (pipe >= tp->snd_ssthresh) { 2594 if (tp->sackhint.recover_fs == 0) 2595 tp->sackhint.recover_fs = 2596 imax(1, tp->snd_nxt - tp->snd_una); 2597 snd_cnt = howmany((long)tp->sackhint.prr_delivered * 2598 tp->snd_ssthresh, tp->sackhint.recover_fs) - 2599 tp->sackhint.prr_out; 2600 } else { 2601 if (V_tcp_do_prr_conservative) 2602 limit = tp->sackhint.prr_delivered - 2603 tp->sackhint.prr_out; 2604 else 2605 limit = imax(tp->sackhint.prr_delivered - 2606 tp->sackhint.prr_out, 2607 del_data) + maxseg; 2608 snd_cnt = imin(tp->snd_ssthresh - pipe, limit); 2609 } 2610 snd_cnt = imax(snd_cnt, 0) / maxseg; 2611 /* 2612 * Send snd_cnt new data into the network in 2613 * response to this ACK. If there is a going 2614 * to be a SACK retransmission, adjust snd_cwnd 2615 * accordingly. 2616 */ 2617 tp->snd_cwnd = imax(maxseg, tp->snd_nxt - tp->snd_recover + 2618 tp->sackhint.sack_bytes_rexmit + (snd_cnt * maxseg)); 2619 } else if ((tp->t_flags & TF_SACK_PERMIT) && 2620 IN_FASTRECOVERY(tp->t_flags)) { 2621 int awnd; 2622 2623 /* 2624 * Compute the amount of data in flight first. 2625 * We can inject new data into the pipe iff 2626 * we have less than 1/2 the original window's 2627 * worth of data in flight. 2628 */ 2629 if (V_tcp_do_rfc6675_pipe) 2630 awnd = tcp_compute_pipe(tp); 2631 else 2632 awnd = (tp->snd_nxt - tp->snd_fack) + 2633 tp->sackhint.sack_bytes_rexmit; 2634 2635 if (awnd < tp->snd_ssthresh) { 2636 tp->snd_cwnd += maxseg; 2637 if (tp->snd_cwnd > tp->snd_ssthresh) 2638 tp->snd_cwnd = tp->snd_ssthresh; 2639 } 2640 } else 2641 tp->snd_cwnd += maxseg; 2642 (void) tp->t_fb->tfb_tcp_output(tp); 2643 goto drop; 2644 } else if (tp->t_dupacks == tcprexmtthresh || 2645 (tp->t_flags & TF_SACK_PERMIT && 2646 V_tcp_do_rfc6675_pipe && 2647 tp->sackhint.sacked_bytes > 2648 (tcprexmtthresh - 1) * maxseg)) { 2649 enter_recovery: 2650 /* 2651 * Above is the RFC6675 trigger condition of 2652 * more than (dupthresh-1)*maxseg sacked data. 2653 * If the count of holes in the 2654 * scoreboard is >= dupthresh, we could 2655 * also enter loss recovery, but don't 2656 * have that value readily available. 2657 */ 2658 tp->t_dupacks = tcprexmtthresh; 2659 tcp_seq onxt = tp->snd_nxt; 2660 2661 /* 2662 * If we're doing sack, or prr, check 2663 * to see if we're already in sack 2664 * recovery. If we're not doing sack, 2665 * check to see if we're in newreno 2666 * recovery. 2667 */ 2668 if (V_tcp_do_prr || 2669 (tp->t_flags & TF_SACK_PERMIT)) { 2670 if (IN_FASTRECOVERY(tp->t_flags)) { 2671 tp->t_dupacks = 0; 2672 break; 2673 } 2674 } else { 2675 if (SEQ_LEQ(th->th_ack, 2676 tp->snd_recover)) { 2677 tp->t_dupacks = 0; 2678 break; 2679 } 2680 } 2681 /* Congestion signal before ack. */ 2682 cc_cong_signal(tp, th, CC_NDUPACK); 2683 cc_ack_received(tp, th, nsegs, 2684 CC_DUPACK); 2685 tcp_timer_activate(tp, TT_REXMT, 0); 2686 tp->t_rtttime = 0; 2687 if (V_tcp_do_prr) { 2688 /* 2689 * snd_ssthresh is already updated by 2690 * cc_cong_signal. 2691 */ 2692 tp->sackhint.prr_delivered = 2693 tp->sackhint.sacked_bytes; 2694 tp->sackhint.recover_fs = max(1, 2695 tp->snd_nxt - tp->snd_una); 2696 } 2697 if (tp->t_flags & TF_SACK_PERMIT) { 2698 TCPSTAT_INC( 2699 tcps_sack_recovery_episode); 2700 tp->snd_recover = tp->snd_nxt; 2701 tp->snd_cwnd = maxseg; 2702 (void) tp->t_fb->tfb_tcp_output(tp); 2703 if (SEQ_GT(th->th_ack, tp->snd_una)) 2704 goto resume_partialack; 2705 goto drop; 2706 } 2707 tp->snd_nxt = th->th_ack; 2708 tp->snd_cwnd = maxseg; 2709 (void) tp->t_fb->tfb_tcp_output(tp); 2710 KASSERT(tp->snd_limited <= 2, 2711 ("%s: tp->snd_limited too big", 2712 __func__)); 2713 tp->snd_cwnd = tp->snd_ssthresh + 2714 maxseg * 2715 (tp->t_dupacks - tp->snd_limited); 2716 if (SEQ_GT(onxt, tp->snd_nxt)) 2717 tp->snd_nxt = onxt; 2718 goto drop; 2719 } else if (V_tcp_do_rfc3042) { 2720 /* 2721 * Process first and second duplicate 2722 * ACKs. Each indicates a segment 2723 * leaving the network, creating room 2724 * for more. Make sure we can send a 2725 * packet on reception of each duplicate 2726 * ACK by increasing snd_cwnd by one 2727 * segment. Restore the original 2728 * snd_cwnd after packet transmission. 2729 */ 2730 cc_ack_received(tp, th, nsegs, 2731 CC_DUPACK); 2732 uint32_t oldcwnd = tp->snd_cwnd; 2733 tcp_seq oldsndmax = tp->snd_max; 2734 u_int sent; 2735 int avail; 2736 2737 KASSERT(tp->t_dupacks == 1 || 2738 tp->t_dupacks == 2, 2739 ("%s: dupacks not 1 or 2", 2740 __func__)); 2741 if (tp->t_dupacks == 1) 2742 tp->snd_limited = 0; 2743 tp->snd_cwnd = 2744 (tp->snd_nxt - tp->snd_una) + 2745 (tp->t_dupacks - tp->snd_limited) * 2746 maxseg; 2747 /* 2748 * Only call tcp_output when there 2749 * is new data available to be sent. 2750 * Otherwise we would send pure ACKs. 2751 */ 2752 SOCKBUF_LOCK(&so->so_snd); 2753 avail = sbavail(&so->so_snd) - 2754 (tp->snd_nxt - tp->snd_una); 2755 SOCKBUF_UNLOCK(&so->so_snd); 2756 if (avail > 0) 2757 (void) tp->t_fb->tfb_tcp_output(tp); 2758 sent = tp->snd_max - oldsndmax; 2759 if (sent > maxseg) { 2760 KASSERT((tp->t_dupacks == 2 && 2761 tp->snd_limited == 0) || 2762 (sent == maxseg + 1 && 2763 tp->t_flags & TF_SENTFIN), 2764 ("%s: sent too much", 2765 __func__)); 2766 tp->snd_limited = 2; 2767 } else if (sent > 0) 2768 ++tp->snd_limited; 2769 tp->snd_cwnd = oldcwnd; 2770 goto drop; 2771 } 2772 } 2773 break; 2774 } else { 2775 /* 2776 * This ack is advancing the left edge, reset the 2777 * counter. 2778 */ 2779 tp->t_dupacks = 0; 2780 /* 2781 * If this ack also has new SACK info, increment the 2782 * counter as per rfc6675. The variable 2783 * sack_changed tracks all changes to the SACK 2784 * scoreboard, including when partial ACKs without 2785 * SACK options are received, and clear the scoreboard 2786 * from the left side. Such partial ACKs should not be 2787 * counted as dupacks here. 2788 */ 2789 if ((tp->t_flags & TF_SACK_PERMIT) && 2790 (to.to_flags & TOF_SACK) && 2791 sack_changed) { 2792 tp->t_dupacks++; 2793 /* limit overhead by setting maxseg last */ 2794 if (!IN_FASTRECOVERY(tp->t_flags) && 2795 (tp->sackhint.sacked_bytes > 2796 ((tcprexmtthresh - 1) * 2797 (maxseg = tcp_maxseg(tp))))) { 2798 goto enter_recovery; 2799 } 2800 } 2801 } 2802 2803 resume_partialack: 2804 KASSERT(SEQ_GT(th->th_ack, tp->snd_una), 2805 ("%s: th_ack <= snd_una", __func__)); 2806 2807 /* 2808 * If the congestion window was inflated to account 2809 * for the other side's cached packets, retract it. 2810 */ 2811 if (IN_FASTRECOVERY(tp->t_flags)) { 2812 if (SEQ_LT(th->th_ack, tp->snd_recover)) { 2813 if (tp->t_flags & TF_SACK_PERMIT) 2814 if (V_tcp_do_prr && to.to_flags & TOF_SACK) 2815 tcp_prr_partialack(tp, th); 2816 else 2817 tcp_sack_partialack(tp, th); 2818 else 2819 tcp_newreno_partial_ack(tp, th); 2820 } else 2821 cc_post_recovery(tp, th); 2822 } 2823 /* 2824 * If we reach this point, ACK is not a duplicate, 2825 * i.e., it ACKs something we sent. 2826 */ 2827 if (tp->t_flags & TF_NEEDSYN) { 2828 /* 2829 * T/TCP: Connection was half-synchronized, and our 2830 * SYN has been ACK'd (so connection is now fully 2831 * synchronized). Go to non-starred state, 2832 * increment snd_una for ACK of SYN, and check if 2833 * we can do window scaling. 2834 */ 2835 tp->t_flags &= ~TF_NEEDSYN; 2836 tp->snd_una++; 2837 /* Do window scaling? */ 2838 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2839 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2840 tp->rcv_scale = tp->request_r_scale; 2841 /* Send window already scaled. */ 2842 } 2843 } 2844 2845 process_ACK: 2846 INP_WLOCK_ASSERT(tp->t_inpcb); 2847 2848 /* 2849 * Adjust for the SYN bit in sequence space, 2850 * but don't account for it in cwnd calculations. 2851 * This is for the SYN_RECEIVED, non-simultaneous 2852 * SYN case. SYN_SENT and simultaneous SYN are 2853 * treated elsewhere. 2854 */ 2855 if (incforsyn) 2856 tp->snd_una++; 2857 acked = BYTES_THIS_ACK(tp, th); 2858 KASSERT(acked >= 0, ("%s: acked unexepectedly negative " 2859 "(tp->snd_una=%u, th->th_ack=%u, tp=%p, m=%p)", __func__, 2860 tp->snd_una, th->th_ack, tp, m)); 2861 TCPSTAT_ADD(tcps_rcvackpack, nsegs); 2862 TCPSTAT_ADD(tcps_rcvackbyte, acked); 2863 2864 /* 2865 * If we just performed our first retransmit, and the ACK 2866 * arrives within our recovery window, then it was a mistake 2867 * to do the retransmit in the first place. Recover our 2868 * original cwnd and ssthresh, and proceed to transmit where 2869 * we left off. 2870 */ 2871 if (tp->t_rxtshift == 1 && 2872 tp->t_flags & TF_PREVVALID && 2873 tp->t_badrxtwin && 2874 SEQ_LT(to.to_tsecr, tp->t_badrxtwin)) 2875 cc_cong_signal(tp, th, CC_RTO_ERR); 2876 2877 /* 2878 * If we have a timestamp reply, update smoothed 2879 * round trip time. If no timestamp is present but 2880 * transmit timer is running and timed sequence 2881 * number was acked, update smoothed round trip time. 2882 * Since we now have an rtt measurement, cancel the 2883 * timer backoff (cf., Phil Karn's retransmit alg.). 2884 * Recompute the initial retransmit timer. 2885 * 2886 * Some boxes send broken timestamp replies 2887 * during the SYN+ACK phase, ignore 2888 * timestamps of 0 or we could calculate a 2889 * huge RTT and blow up the retransmit timer. 2890 */ 2891 if ((to.to_flags & TOF_TS) != 0 && to.to_tsecr) { 2892 uint32_t t; 2893 2894 t = tcp_ts_getticks() - to.to_tsecr; 2895 if (!tp->t_rttlow || tp->t_rttlow > t) 2896 tp->t_rttlow = t; 2897 tcp_xmit_timer(tp, TCP_TS_TO_TICKS(t) + 1); 2898 } else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) { 2899 if (!tp->t_rttlow || tp->t_rttlow > ticks - tp->t_rtttime) 2900 tp->t_rttlow = ticks - tp->t_rtttime; 2901 tcp_xmit_timer(tp, ticks - tp->t_rtttime); 2902 } 2903 2904 /* 2905 * If all outstanding data is acked, stop retransmit 2906 * timer and remember to restart (more output or persist). 2907 * If there is more data to be acked, restart retransmit 2908 * timer, using current (possibly backed-off) value. 2909 */ 2910 if (th->th_ack == tp->snd_max) { 2911 tcp_timer_activate(tp, TT_REXMT, 0); 2912 needoutput = 1; 2913 } else if (!tcp_timer_active(tp, TT_PERSIST)) 2914 tcp_timer_activate(tp, TT_REXMT, tp->t_rxtcur); 2915 2916 /* 2917 * If no data (only SYN) was ACK'd, 2918 * skip rest of ACK processing. 2919 */ 2920 if (acked == 0) 2921 goto step6; 2922 2923 /* 2924 * Let the congestion control algorithm update congestion 2925 * control related information. This typically means increasing 2926 * the congestion window. 2927 */ 2928 cc_ack_received(tp, th, nsegs, CC_ACK); 2929 2930 SOCKBUF_LOCK(&so->so_snd); 2931 if (acked > sbavail(&so->so_snd)) { 2932 if (tp->snd_wnd >= sbavail(&so->so_snd)) 2933 tp->snd_wnd -= sbavail(&so->so_snd); 2934 else 2935 tp->snd_wnd = 0; 2936 mfree = sbcut_locked(&so->so_snd, 2937 (int)sbavail(&so->so_snd)); 2938 ourfinisacked = 1; 2939 } else { 2940 mfree = sbcut_locked(&so->so_snd, acked); 2941 if (tp->snd_wnd >= (uint32_t) acked) 2942 tp->snd_wnd -= acked; 2943 else 2944 tp->snd_wnd = 0; 2945 ourfinisacked = 0; 2946 } 2947 SOCKBUF_UNLOCK(&so->so_snd); 2948 tp->t_flags |= TF_WAKESOW; 2949 m_freem(mfree); 2950 /* Detect una wraparound. */ 2951 if (!IN_RECOVERY(tp->t_flags) && 2952 SEQ_GT(tp->snd_una, tp->snd_recover) && 2953 SEQ_LEQ(th->th_ack, tp->snd_recover)) 2954 tp->snd_recover = th->th_ack - 1; 2955 /* XXXLAS: Can this be moved up into cc_post_recovery? */ 2956 if (IN_RECOVERY(tp->t_flags) && 2957 SEQ_GEQ(th->th_ack, tp->snd_recover)) { 2958 EXIT_RECOVERY(tp->t_flags); 2959 } 2960 tp->snd_una = th->th_ack; 2961 if (tp->t_flags & TF_SACK_PERMIT) { 2962 if (SEQ_GT(tp->snd_una, tp->snd_recover)) 2963 tp->snd_recover = tp->snd_una; 2964 } 2965 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2966 tp->snd_nxt = tp->snd_una; 2967 2968 switch (tp->t_state) { 2969 /* 2970 * In FIN_WAIT_1 STATE in addition to the processing 2971 * for the ESTABLISHED state if our FIN is now acknowledged 2972 * then enter FIN_WAIT_2. 2973 */ 2974 case TCPS_FIN_WAIT_1: 2975 if (ourfinisacked) { 2976 /* 2977 * If we can't receive any more 2978 * data, then closing user can proceed. 2979 * Starting the timer is contrary to the 2980 * specification, but if we don't get a FIN 2981 * we'll hang forever. 2982 * 2983 * XXXjl: 2984 * we should release the tp also, and use a 2985 * compressed state. 2986 */ 2987 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 2988 soisdisconnected(so); 2989 tcp_timer_activate(tp, TT_2MSL, 2990 (tcp_fast_finwait2_recycle ? 2991 tcp_finwait2_timeout : 2992 TP_MAXIDLE(tp))); 2993 } 2994 tcp_state_change(tp, TCPS_FIN_WAIT_2); 2995 } 2996 break; 2997 2998 /* 2999 * In CLOSING STATE in addition to the processing for 3000 * the ESTABLISHED state if the ACK acknowledges our FIN 3001 * then enter the TIME-WAIT state, otherwise ignore 3002 * the segment. 3003 */ 3004 case TCPS_CLOSING: 3005 if (ourfinisacked) { 3006 tcp_twstart(tp); 3007 m_freem(m); 3008 return; 3009 } 3010 break; 3011 3012 /* 3013 * In LAST_ACK, we may still be waiting for data to drain 3014 * and/or to be acked, as well as for the ack of our FIN. 3015 * If our FIN is now acknowledged, delete the TCB, 3016 * enter the closed state and return. 3017 */ 3018 case TCPS_LAST_ACK: 3019 if (ourfinisacked) { 3020 tp = tcp_close(tp); 3021 goto drop; 3022 } 3023 break; 3024 } 3025 } 3026 3027 step6: 3028 INP_WLOCK_ASSERT(tp->t_inpcb); 3029 3030 /* 3031 * Update window information. 3032 * Don't look at window if no ACK: TAC's send garbage on first SYN. 3033 */ 3034 if ((thflags & TH_ACK) && 3035 (SEQ_LT(tp->snd_wl1, th->th_seq) || 3036 (tp->snd_wl1 == th->th_seq && (SEQ_LT(tp->snd_wl2, th->th_ack) || 3037 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))) { 3038 /* keep track of pure window updates */ 3039 if (tlen == 0 && 3040 tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) 3041 TCPSTAT_INC(tcps_rcvwinupd); 3042 tp->snd_wnd = tiwin; 3043 tp->snd_wl1 = th->th_seq; 3044 tp->snd_wl2 = th->th_ack; 3045 if (tp->snd_wnd > tp->max_sndwnd) 3046 tp->max_sndwnd = tp->snd_wnd; 3047 needoutput = 1; 3048 } 3049 3050 /* 3051 * Process segments with URG. 3052 */ 3053 if ((thflags & TH_URG) && th->th_urp && 3054 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3055 /* 3056 * This is a kludge, but if we receive and accept 3057 * random urgent pointers, we'll crash in 3058 * soreceive. It's hard to imagine someone 3059 * actually wanting to send this much urgent data. 3060 */ 3061 SOCKBUF_LOCK(&so->so_rcv); 3062 if (th->th_urp + sbavail(&so->so_rcv) > sb_max) { 3063 th->th_urp = 0; /* XXX */ 3064 thflags &= ~TH_URG; /* XXX */ 3065 SOCKBUF_UNLOCK(&so->so_rcv); /* XXX */ 3066 goto dodata; /* XXX */ 3067 } 3068 /* 3069 * If this segment advances the known urgent pointer, 3070 * then mark the data stream. This should not happen 3071 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 3072 * a FIN has been received from the remote side. 3073 * In these states we ignore the URG. 3074 * 3075 * According to RFC961 (Assigned Protocols), 3076 * the urgent pointer points to the last octet 3077 * of urgent data. We continue, however, 3078 * to consider it to indicate the first octet 3079 * of data past the urgent section as the original 3080 * spec states (in one of two places). 3081 */ 3082 if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) { 3083 tp->rcv_up = th->th_seq + th->th_urp; 3084 so->so_oobmark = sbavail(&so->so_rcv) + 3085 (tp->rcv_up - tp->rcv_nxt) - 1; 3086 if (so->so_oobmark == 0) 3087 so->so_rcv.sb_state |= SBS_RCVATMARK; 3088 sohasoutofband(so); 3089 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); 3090 } 3091 SOCKBUF_UNLOCK(&so->so_rcv); 3092 /* 3093 * Remove out of band data so doesn't get presented to user. 3094 * This can happen independent of advancing the URG pointer, 3095 * but if two URG's are pending at once, some out-of-band 3096 * data may creep in... ick. 3097 */ 3098 if (th->th_urp <= (uint32_t)tlen && 3099 !(so->so_options & SO_OOBINLINE)) { 3100 /* hdr drop is delayed */ 3101 tcp_pulloutofband(so, th, m, drop_hdrlen); 3102 } 3103 } else { 3104 /* 3105 * If no out of band data is expected, 3106 * pull receive urgent pointer along 3107 * with the receive window. 3108 */ 3109 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) 3110 tp->rcv_up = tp->rcv_nxt; 3111 } 3112 dodata: /* XXX */ 3113 INP_WLOCK_ASSERT(tp->t_inpcb); 3114 3115 /* 3116 * Process the segment text, merging it into the TCP sequencing queue, 3117 * and arranging for acknowledgment of receipt if necessary. 3118 * This process logically involves adjusting tp->rcv_wnd as data 3119 * is presented to the user (this happens in tcp_usrreq.c, 3120 * case PRU_RCVD). If a FIN has already been received on this 3121 * connection then we just ignore the text. 3122 */ 3123 tfo_syn = ((tp->t_state == TCPS_SYN_RECEIVED) && 3124 IS_FASTOPEN(tp->t_flags)); 3125 if ((tlen || (thflags & TH_FIN) || (tfo_syn && tlen > 0)) && 3126 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3127 tcp_seq save_start = th->th_seq; 3128 tcp_seq save_rnxt = tp->rcv_nxt; 3129 int save_tlen = tlen; 3130 m_adj(m, drop_hdrlen); /* delayed header drop */ 3131 /* 3132 * Insert segment which includes th into TCP reassembly queue 3133 * with control block tp. Set thflags to whether reassembly now 3134 * includes a segment with FIN. This handles the common case 3135 * inline (segment is the next to be received on an established 3136 * connection, and the queue is empty), avoiding linkage into 3137 * and removal from the queue and repetition of various 3138 * conversions. 3139 * Set DELACK for segments received in order, but ack 3140 * immediately when segments are out of order (so 3141 * fast retransmit can work). 3142 */ 3143 if (th->th_seq == tp->rcv_nxt && 3144 SEGQ_EMPTY(tp) && 3145 (TCPS_HAVEESTABLISHED(tp->t_state) || 3146 tfo_syn)) { 3147 if (DELAY_ACK(tp, tlen) || tfo_syn) 3148 tp->t_flags |= TF_DELACK; 3149 else 3150 tp->t_flags |= TF_ACKNOW; 3151 tp->rcv_nxt += tlen; 3152 if (tlen && 3153 ((tp->t_flags2 & TF2_FBYTES_COMPLETE) == 0) && 3154 (tp->t_fbyte_in == 0)) { 3155 tp->t_fbyte_in = ticks; 3156 if (tp->t_fbyte_in == 0) 3157 tp->t_fbyte_in = 1; 3158 if (tp->t_fbyte_out && tp->t_fbyte_in) 3159 tp->t_flags2 |= TF2_FBYTES_COMPLETE; 3160 } 3161 thflags = th->th_flags & TH_FIN; 3162 TCPSTAT_INC(tcps_rcvpack); 3163 TCPSTAT_ADD(tcps_rcvbyte, tlen); 3164 SOCKBUF_LOCK(&so->so_rcv); 3165 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) 3166 m_freem(m); 3167 else 3168 sbappendstream_locked(&so->so_rcv, m, 0); 3169 SOCKBUF_UNLOCK(&so->so_rcv); 3170 tp->t_flags |= TF_WAKESOR; 3171 } else { 3172 /* 3173 * XXX: Due to the header drop above "th" is 3174 * theoretically invalid by now. Fortunately 3175 * m_adj() doesn't actually frees any mbufs 3176 * when trimming from the head. 3177 */ 3178 tcp_seq temp = save_start; 3179 thflags = tcp_reass(tp, th, &temp, &tlen, m); 3180 tp->t_flags |= TF_ACKNOW; 3181 } 3182 if ((tp->t_flags & TF_SACK_PERMIT) && 3183 (save_tlen > 0) && 3184 TCPS_HAVEESTABLISHED(tp->t_state)) { 3185 if ((tlen == 0) && (SEQ_LT(save_start, save_rnxt))) { 3186 /* 3187 * DSACK actually handled in the fastpath 3188 * above. 3189 */ 3190 tcp_update_sack_list(tp, save_start, 3191 save_start + save_tlen); 3192 } else if ((tlen > 0) && SEQ_GT(tp->rcv_nxt, save_rnxt)) { 3193 if ((tp->rcv_numsacks >= 1) && 3194 (tp->sackblks[0].end == save_start)) { 3195 /* 3196 * Partial overlap, recorded at todrop 3197 * above. 3198 */ 3199 tcp_update_sack_list(tp, 3200 tp->sackblks[0].start, 3201 tp->sackblks[0].end); 3202 } else { 3203 tcp_update_dsack_list(tp, save_start, 3204 save_start + save_tlen); 3205 } 3206 } else if (tlen >= save_tlen) { 3207 /* Update of sackblks. */ 3208 tcp_update_dsack_list(tp, save_start, 3209 save_start + save_tlen); 3210 } else if (tlen > 0) { 3211 tcp_update_dsack_list(tp, save_start, 3212 save_start + tlen); 3213 } 3214 } 3215 #if 0 3216 /* 3217 * Note the amount of data that peer has sent into 3218 * our window, in order to estimate the sender's 3219 * buffer size. 3220 * XXX: Unused. 3221 */ 3222 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt)) 3223 len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); 3224 else 3225 len = so->so_rcv.sb_hiwat; 3226 #endif 3227 } else { 3228 m_freem(m); 3229 thflags &= ~TH_FIN; 3230 } 3231 3232 /* 3233 * If FIN is received ACK the FIN and let the user know 3234 * that the connection is closing. 3235 */ 3236 if (thflags & TH_FIN) { 3237 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3238 socantrcvmore(so); 3239 /* The socket upcall is handled by socantrcvmore. */ 3240 tp->t_flags &= ~TF_WAKESOR; 3241 /* 3242 * If connection is half-synchronized 3243 * (ie NEEDSYN flag on) then delay ACK, 3244 * so it may be piggybacked when SYN is sent. 3245 * Otherwise, since we received a FIN then no 3246 * more input can be expected, send ACK now. 3247 */ 3248 if (tp->t_flags & TF_NEEDSYN) 3249 tp->t_flags |= TF_DELACK; 3250 else 3251 tp->t_flags |= TF_ACKNOW; 3252 tp->rcv_nxt++; 3253 } 3254 switch (tp->t_state) { 3255 /* 3256 * In SYN_RECEIVED and ESTABLISHED STATES 3257 * enter the CLOSE_WAIT state. 3258 */ 3259 case TCPS_SYN_RECEIVED: 3260 tp->t_starttime = ticks; 3261 /* FALLTHROUGH */ 3262 case TCPS_ESTABLISHED: 3263 tcp_state_change(tp, TCPS_CLOSE_WAIT); 3264 break; 3265 3266 /* 3267 * If still in FIN_WAIT_1 STATE FIN has not been acked so 3268 * enter the CLOSING state. 3269 */ 3270 case TCPS_FIN_WAIT_1: 3271 tcp_state_change(tp, TCPS_CLOSING); 3272 break; 3273 3274 /* 3275 * In FIN_WAIT_2 state enter the TIME_WAIT state, 3276 * starting the time-wait timer, turning off the other 3277 * standard timers. 3278 */ 3279 case TCPS_FIN_WAIT_2: 3280 tcp_twstart(tp); 3281 return; 3282 } 3283 } 3284 #ifdef TCPDEBUG 3285 if (so->so_options & SO_DEBUG) 3286 tcp_trace(TA_INPUT, ostate, tp, (void *)tcp_saveipgen, 3287 &tcp_savetcp, 0); 3288 #endif 3289 TCP_PROBE3(debug__input, tp, th, m); 3290 3291 /* 3292 * Return any desired output. 3293 */ 3294 if (needoutput || (tp->t_flags & TF_ACKNOW)) 3295 (void) tp->t_fb->tfb_tcp_output(tp); 3296 3297 check_delack: 3298 INP_WLOCK_ASSERT(tp->t_inpcb); 3299 3300 if (tp->t_flags & TF_DELACK) { 3301 tp->t_flags &= ~TF_DELACK; 3302 tcp_timer_activate(tp, TT_DELACK, tcp_delacktime); 3303 } 3304 tcp_handle_wakeup(tp, so); 3305 INP_WUNLOCK(tp->t_inpcb); 3306 return; 3307 3308 dropafterack: 3309 /* 3310 * Generate an ACK dropping incoming segment if it occupies 3311 * sequence space, where the ACK reflects our state. 3312 * 3313 * We can now skip the test for the RST flag since all 3314 * paths to this code happen after packets containing 3315 * RST have been dropped. 3316 * 3317 * In the SYN-RECEIVED state, don't send an ACK unless the 3318 * segment we received passes the SYN-RECEIVED ACK test. 3319 * If it fails send a RST. This breaks the loop in the 3320 * "LAND" DoS attack, and also prevents an ACK storm 3321 * between two listening ports that have been sent forged 3322 * SYN segments, each with the source address of the other. 3323 */ 3324 if (tp->t_state == TCPS_SYN_RECEIVED && (thflags & TH_ACK) && 3325 (SEQ_GT(tp->snd_una, th->th_ack) || 3326 SEQ_GT(th->th_ack, tp->snd_max)) ) { 3327 rstreason = BANDLIM_RST_OPENPORT; 3328 goto dropwithreset; 3329 } 3330 #ifdef TCPDEBUG 3331 if (so->so_options & SO_DEBUG) 3332 tcp_trace(TA_DROP, ostate, tp, (void *)tcp_saveipgen, 3333 &tcp_savetcp, 0); 3334 #endif 3335 TCP_PROBE3(debug__input, tp, th, m); 3336 tp->t_flags |= TF_ACKNOW; 3337 (void) tp->t_fb->tfb_tcp_output(tp); 3338 tcp_handle_wakeup(tp, so); 3339 INP_WUNLOCK(tp->t_inpcb); 3340 m_freem(m); 3341 return; 3342 3343 dropwithreset: 3344 if (tp != NULL) { 3345 tcp_dropwithreset(m, th, tp, tlen, rstreason); 3346 tcp_handle_wakeup(tp, so); 3347 INP_WUNLOCK(tp->t_inpcb); 3348 } else 3349 tcp_dropwithreset(m, th, NULL, tlen, rstreason); 3350 return; 3351 3352 drop: 3353 /* 3354 * Drop space held by incoming segment and return. 3355 */ 3356 #ifdef TCPDEBUG 3357 if (tp == NULL || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 3358 tcp_trace(TA_DROP, ostate, tp, (void *)tcp_saveipgen, 3359 &tcp_savetcp, 0); 3360 #endif 3361 TCP_PROBE3(debug__input, tp, th, m); 3362 if (tp != NULL) { 3363 tcp_handle_wakeup(tp, so); 3364 INP_WUNLOCK(tp->t_inpcb); 3365 } 3366 m_freem(m); 3367 } 3368 3369 /* 3370 * Issue RST and make ACK acceptable to originator of segment. 3371 * The mbuf must still include the original packet header. 3372 * tp may be NULL. 3373 */ 3374 void 3375 tcp_dropwithreset(struct mbuf *m, struct tcphdr *th, struct tcpcb *tp, 3376 int tlen, int rstreason) 3377 { 3378 #ifdef INET 3379 struct ip *ip; 3380 #endif 3381 #ifdef INET6 3382 struct ip6_hdr *ip6; 3383 #endif 3384 3385 if (tp != NULL) { 3386 INP_WLOCK_ASSERT(tp->t_inpcb); 3387 } 3388 3389 /* Don't bother if destination was broadcast/multicast. */ 3390 if ((th->th_flags & TH_RST) || m->m_flags & (M_BCAST|M_MCAST)) 3391 goto drop; 3392 #ifdef INET6 3393 if (mtod(m, struct ip *)->ip_v == 6) { 3394 ip6 = mtod(m, struct ip6_hdr *); 3395 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 3396 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) 3397 goto drop; 3398 /* IPv6 anycast check is done at tcp6_input() */ 3399 } 3400 #endif 3401 #if defined(INET) && defined(INET6) 3402 else 3403 #endif 3404 #ifdef INET 3405 { 3406 ip = mtod(m, struct ip *); 3407 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || 3408 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 3409 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || 3410 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 3411 goto drop; 3412 } 3413 #endif 3414 3415 /* Perform bandwidth limiting. */ 3416 if (badport_bandlim(rstreason) < 0) 3417 goto drop; 3418 3419 /* tcp_respond consumes the mbuf chain. */ 3420 if (th->th_flags & TH_ACK) { 3421 tcp_respond(tp, mtod(m, void *), th, m, (tcp_seq)0, 3422 th->th_ack, TH_RST); 3423 } else { 3424 if (th->th_flags & TH_SYN) 3425 tlen++; 3426 if (th->th_flags & TH_FIN) 3427 tlen++; 3428 tcp_respond(tp, mtod(m, void *), th, m, th->th_seq+tlen, 3429 (tcp_seq)0, TH_RST|TH_ACK); 3430 } 3431 return; 3432 drop: 3433 m_freem(m); 3434 } 3435 3436 /* 3437 * Parse TCP options and place in tcpopt. 3438 */ 3439 void 3440 tcp_dooptions(struct tcpopt *to, u_char *cp, int cnt, int flags) 3441 { 3442 int opt, optlen; 3443 3444 to->to_flags = 0; 3445 for (; cnt > 0; cnt -= optlen, cp += optlen) { 3446 opt = cp[0]; 3447 if (opt == TCPOPT_EOL) 3448 break; 3449 if (opt == TCPOPT_NOP) 3450 optlen = 1; 3451 else { 3452 if (cnt < 2) 3453 break; 3454 optlen = cp[1]; 3455 if (optlen < 2 || optlen > cnt) 3456 break; 3457 } 3458 switch (opt) { 3459 case TCPOPT_MAXSEG: 3460 if (optlen != TCPOLEN_MAXSEG) 3461 continue; 3462 if (!(flags & TO_SYN)) 3463 continue; 3464 to->to_flags |= TOF_MSS; 3465 bcopy((char *)cp + 2, 3466 (char *)&to->to_mss, sizeof(to->to_mss)); 3467 to->to_mss = ntohs(to->to_mss); 3468 break; 3469 case TCPOPT_WINDOW: 3470 if (optlen != TCPOLEN_WINDOW) 3471 continue; 3472 if (!(flags & TO_SYN)) 3473 continue; 3474 to->to_flags |= TOF_SCALE; 3475 to->to_wscale = min(cp[2], TCP_MAX_WINSHIFT); 3476 break; 3477 case TCPOPT_TIMESTAMP: 3478 if (optlen != TCPOLEN_TIMESTAMP) 3479 continue; 3480 to->to_flags |= TOF_TS; 3481 bcopy((char *)cp + 2, 3482 (char *)&to->to_tsval, sizeof(to->to_tsval)); 3483 to->to_tsval = ntohl(to->to_tsval); 3484 bcopy((char *)cp + 6, 3485 (char *)&to->to_tsecr, sizeof(to->to_tsecr)); 3486 to->to_tsecr = ntohl(to->to_tsecr); 3487 break; 3488 case TCPOPT_SIGNATURE: 3489 /* 3490 * In order to reply to a host which has set the 3491 * TCP_SIGNATURE option in its initial SYN, we have 3492 * to record the fact that the option was observed 3493 * here for the syncache code to perform the correct 3494 * response. 3495 */ 3496 if (optlen != TCPOLEN_SIGNATURE) 3497 continue; 3498 to->to_flags |= TOF_SIGNATURE; 3499 to->to_signature = cp + 2; 3500 break; 3501 case TCPOPT_SACK_PERMITTED: 3502 if (optlen != TCPOLEN_SACK_PERMITTED) 3503 continue; 3504 if (!(flags & TO_SYN)) 3505 continue; 3506 if (!V_tcp_do_sack) 3507 continue; 3508 to->to_flags |= TOF_SACKPERM; 3509 break; 3510 case TCPOPT_SACK: 3511 if (optlen <= 2 || (optlen - 2) % TCPOLEN_SACK != 0) 3512 continue; 3513 if (flags & TO_SYN) 3514 continue; 3515 to->to_flags |= TOF_SACK; 3516 to->to_nsacks = (optlen - 2) / TCPOLEN_SACK; 3517 to->to_sacks = cp + 2; 3518 TCPSTAT_INC(tcps_sack_rcv_blocks); 3519 break; 3520 case TCPOPT_FAST_OPEN: 3521 /* 3522 * Cookie length validation is performed by the 3523 * server side cookie checking code or the client 3524 * side cookie cache update code. 3525 */ 3526 if (!(flags & TO_SYN)) 3527 continue; 3528 if (!V_tcp_fastopen_client_enable && 3529 !V_tcp_fastopen_server_enable) 3530 continue; 3531 to->to_flags |= TOF_FASTOPEN; 3532 to->to_tfo_len = optlen - 2; 3533 to->to_tfo_cookie = to->to_tfo_len ? cp + 2 : NULL; 3534 break; 3535 default: 3536 continue; 3537 } 3538 } 3539 } 3540 3541 /* 3542 * Pull out of band byte out of a segment so 3543 * it doesn't appear in the user's data queue. 3544 * It is still reflected in the segment length for 3545 * sequencing purposes. 3546 */ 3547 void 3548 tcp_pulloutofband(struct socket *so, struct tcphdr *th, struct mbuf *m, 3549 int off) 3550 { 3551 int cnt = off + th->th_urp - 1; 3552 3553 while (cnt >= 0) { 3554 if (m->m_len > cnt) { 3555 char *cp = mtod(m, caddr_t) + cnt; 3556 struct tcpcb *tp = sototcpcb(so); 3557 3558 INP_WLOCK_ASSERT(tp->t_inpcb); 3559 3560 tp->t_iobc = *cp; 3561 tp->t_oobflags |= TCPOOB_HAVEDATA; 3562 bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); 3563 m->m_len--; 3564 if (m->m_flags & M_PKTHDR) 3565 m->m_pkthdr.len--; 3566 return; 3567 } 3568 cnt -= m->m_len; 3569 m = m->m_next; 3570 if (m == NULL) 3571 break; 3572 } 3573 panic("tcp_pulloutofband"); 3574 } 3575 3576 /* 3577 * Collect new round-trip time estimate 3578 * and update averages and current timeout. 3579 */ 3580 void 3581 tcp_xmit_timer(struct tcpcb *tp, int rtt) 3582 { 3583 int delta; 3584 3585 INP_WLOCK_ASSERT(tp->t_inpcb); 3586 3587 TCPSTAT_INC(tcps_rttupdated); 3588 tp->t_rttupdated++; 3589 #ifdef STATS 3590 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_RTT, 3591 imax(0, rtt * 1000 / hz)); 3592 #endif 3593 if ((tp->t_srtt != 0) && (tp->t_rxtshift <= TCP_RTT_INVALIDATE)) { 3594 /* 3595 * srtt is stored as fixed point with 5 bits after the 3596 * binary point (i.e., scaled by 8). The following magic 3597 * is equivalent to the smoothing algorithm in rfc793 with 3598 * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed 3599 * point). Adjust rtt to origin 0. 3600 */ 3601 delta = ((rtt - 1) << TCP_DELTA_SHIFT) 3602 - (tp->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT)); 3603 3604 if ((tp->t_srtt += delta) <= 0) 3605 tp->t_srtt = 1; 3606 3607 /* 3608 * We accumulate a smoothed rtt variance (actually, a 3609 * smoothed mean difference), then set the retransmit 3610 * timer to smoothed rtt + 4 times the smoothed variance. 3611 * rttvar is stored as fixed point with 4 bits after the 3612 * binary point (scaled by 16). The following is 3613 * equivalent to rfc793 smoothing with an alpha of .75 3614 * (rttvar = rttvar*3/4 + |delta| / 4). This replaces 3615 * rfc793's wired-in beta. 3616 */ 3617 if (delta < 0) 3618 delta = -delta; 3619 delta -= tp->t_rttvar >> (TCP_RTTVAR_SHIFT - TCP_DELTA_SHIFT); 3620 if ((tp->t_rttvar += delta) <= 0) 3621 tp->t_rttvar = 1; 3622 if (tp->t_rttbest > tp->t_srtt + tp->t_rttvar) 3623 tp->t_rttbest = tp->t_srtt + tp->t_rttvar; 3624 } else { 3625 /* 3626 * No rtt measurement yet - use the unsmoothed rtt. 3627 * Set the variance to half the rtt (so our first 3628 * retransmit happens at 3*rtt). 3629 */ 3630 tp->t_srtt = rtt << TCP_RTT_SHIFT; 3631 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1); 3632 tp->t_rttbest = tp->t_srtt + tp->t_rttvar; 3633 } 3634 tp->t_rtttime = 0; 3635 tp->t_rxtshift = 0; 3636 3637 /* 3638 * the retransmit should happen at rtt + 4 * rttvar. 3639 * Because of the way we do the smoothing, srtt and rttvar 3640 * will each average +1/2 tick of bias. When we compute 3641 * the retransmit timer, we want 1/2 tick of rounding and 3642 * 1 extra tick because of +-1/2 tick uncertainty in the 3643 * firing of the timer. The bias will give us exactly the 3644 * 1.5 tick we need. But, because the bias is 3645 * statistical, we have to test that we don't drop below 3646 * the minimum feasible timer (which is 2 ticks). 3647 */ 3648 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), 3649 max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX); 3650 3651 /* 3652 * We received an ack for a packet that wasn't retransmitted; 3653 * it is probably safe to discard any error indications we've 3654 * received recently. This isn't quite right, but close enough 3655 * for now (a route might have failed after we sent a segment, 3656 * and the return path might not be symmetrical). 3657 */ 3658 tp->t_softerror = 0; 3659 } 3660 3661 /* 3662 * Determine a reasonable value for maxseg size. 3663 * If the route is known, check route for mtu. 3664 * If none, use an mss that can be handled on the outgoing interface 3665 * without forcing IP to fragment. If no route is found, route has no mtu, 3666 * or the destination isn't local, use a default, hopefully conservative 3667 * size (usually 512 or the default IP max size, but no more than the mtu 3668 * of the interface), as we can't discover anything about intervening 3669 * gateways or networks. We also initialize the congestion/slow start 3670 * window to be a single segment if the destination isn't local. 3671 * While looking at the routing entry, we also initialize other path-dependent 3672 * parameters from pre-set or cached values in the routing entry. 3673 * 3674 * NOTE that resulting t_maxseg doesn't include space for TCP options or 3675 * IP options, e.g. IPSEC data, since length of this data may vary, and 3676 * thus it is calculated for every segment separately in tcp_output(). 3677 * 3678 * NOTE that this routine is only called when we process an incoming 3679 * segment, or an ICMP need fragmentation datagram. Outgoing SYN/ACK MSS 3680 * settings are handled in tcp_mssopt(). 3681 */ 3682 void 3683 tcp_mss_update(struct tcpcb *tp, int offer, int mtuoffer, 3684 struct hc_metrics_lite *metricptr, struct tcp_ifcap *cap) 3685 { 3686 int mss = 0; 3687 uint32_t maxmtu = 0; 3688 struct inpcb *inp = tp->t_inpcb; 3689 struct hc_metrics_lite metrics; 3690 #ifdef INET6 3691 int isipv6 = ((inp->inp_vflag & INP_IPV6) != 0) ? 1 : 0; 3692 size_t min_protoh = isipv6 ? 3693 sizeof (struct ip6_hdr) + sizeof (struct tcphdr) : 3694 sizeof (struct tcpiphdr); 3695 #else 3696 const size_t min_protoh = sizeof(struct tcpiphdr); 3697 #endif 3698 3699 INP_WLOCK_ASSERT(tp->t_inpcb); 3700 3701 if (mtuoffer != -1) { 3702 KASSERT(offer == -1, ("%s: conflict", __func__)); 3703 offer = mtuoffer - min_protoh; 3704 } 3705 3706 /* Initialize. */ 3707 #ifdef INET6 3708 if (isipv6) { 3709 maxmtu = tcp_maxmtu6(&inp->inp_inc, cap); 3710 tp->t_maxseg = V_tcp_v6mssdflt; 3711 } 3712 #endif 3713 #if defined(INET) && defined(INET6) 3714 else 3715 #endif 3716 #ifdef INET 3717 { 3718 maxmtu = tcp_maxmtu(&inp->inp_inc, cap); 3719 tp->t_maxseg = V_tcp_mssdflt; 3720 } 3721 #endif 3722 3723 /* 3724 * No route to sender, stay with default mss and return. 3725 */ 3726 if (maxmtu == 0) { 3727 /* 3728 * In case we return early we need to initialize metrics 3729 * to a defined state as tcp_hc_get() would do for us 3730 * if there was no cache hit. 3731 */ 3732 if (metricptr != NULL) 3733 bzero(metricptr, sizeof(struct hc_metrics_lite)); 3734 return; 3735 } 3736 3737 /* What have we got? */ 3738 switch (offer) { 3739 case 0: 3740 /* 3741 * Offer == 0 means that there was no MSS on the SYN 3742 * segment, in this case we use tcp_mssdflt as 3743 * already assigned to t_maxseg above. 3744 */ 3745 offer = tp->t_maxseg; 3746 break; 3747 3748 case -1: 3749 /* 3750 * Offer == -1 means that we didn't receive SYN yet. 3751 */ 3752 /* FALLTHROUGH */ 3753 3754 default: 3755 /* 3756 * Prevent DoS attack with too small MSS. Round up 3757 * to at least minmss. 3758 */ 3759 offer = max(offer, V_tcp_minmss); 3760 } 3761 3762 /* 3763 * rmx information is now retrieved from tcp_hostcache. 3764 */ 3765 tcp_hc_get(&inp->inp_inc, &metrics); 3766 if (metricptr != NULL) 3767 bcopy(&metrics, metricptr, sizeof(struct hc_metrics_lite)); 3768 3769 /* 3770 * If there's a discovered mtu in tcp hostcache, use it. 3771 * Else, use the link mtu. 3772 */ 3773 if (metrics.rmx_mtu) 3774 mss = min(metrics.rmx_mtu, maxmtu) - min_protoh; 3775 else { 3776 #ifdef INET6 3777 if (isipv6) { 3778 mss = maxmtu - min_protoh; 3779 if (!V_path_mtu_discovery && 3780 !in6_localaddr(&inp->in6p_faddr)) 3781 mss = min(mss, V_tcp_v6mssdflt); 3782 } 3783 #endif 3784 #if defined(INET) && defined(INET6) 3785 else 3786 #endif 3787 #ifdef INET 3788 { 3789 mss = maxmtu - min_protoh; 3790 if (!V_path_mtu_discovery && 3791 !in_localaddr(inp->inp_faddr)) 3792 mss = min(mss, V_tcp_mssdflt); 3793 } 3794 #endif 3795 /* 3796 * XXX - The above conditional (mss = maxmtu - min_protoh) 3797 * probably violates the TCP spec. 3798 * The problem is that, since we don't know the 3799 * other end's MSS, we are supposed to use a conservative 3800 * default. But, if we do that, then MTU discovery will 3801 * never actually take place, because the conservative 3802 * default is much less than the MTUs typically seen 3803 * on the Internet today. For the moment, we'll sweep 3804 * this under the carpet. 3805 * 3806 * The conservative default might not actually be a problem 3807 * if the only case this occurs is when sending an initial 3808 * SYN with options and data to a host we've never talked 3809 * to before. Then, they will reply with an MSS value which 3810 * will get recorded and the new parameters should get 3811 * recomputed. For Further Study. 3812 */ 3813 } 3814 mss = min(mss, offer); 3815 3816 /* 3817 * Sanity check: make sure that maxseg will be large 3818 * enough to allow some data on segments even if the 3819 * all the option space is used (40bytes). Otherwise 3820 * funny things may happen in tcp_output. 3821 * 3822 * XXXGL: shouldn't we reserve space for IP/IPv6 options? 3823 */ 3824 mss = max(mss, 64); 3825 3826 tp->t_maxseg = mss; 3827 } 3828 3829 void 3830 tcp_mss(struct tcpcb *tp, int offer) 3831 { 3832 int mss; 3833 uint32_t bufsize; 3834 struct inpcb *inp; 3835 struct socket *so; 3836 struct hc_metrics_lite metrics; 3837 struct tcp_ifcap cap; 3838 3839 KASSERT(tp != NULL, ("%s: tp == NULL", __func__)); 3840 3841 bzero(&cap, sizeof(cap)); 3842 tcp_mss_update(tp, offer, -1, &metrics, &cap); 3843 3844 mss = tp->t_maxseg; 3845 inp = tp->t_inpcb; 3846 3847 /* 3848 * If there's a pipesize, change the socket buffer to that size, 3849 * don't change if sb_hiwat is different than default (then it 3850 * has been changed on purpose with setsockopt). 3851 * Make the socket buffers an integral number of mss units; 3852 * if the mss is larger than the socket buffer, decrease the mss. 3853 */ 3854 so = inp->inp_socket; 3855 SOCKBUF_LOCK(&so->so_snd); 3856 if ((so->so_snd.sb_hiwat == V_tcp_sendspace) && metrics.rmx_sendpipe) 3857 bufsize = metrics.rmx_sendpipe; 3858 else 3859 bufsize = so->so_snd.sb_hiwat; 3860 if (bufsize < mss) 3861 mss = bufsize; 3862 else { 3863 bufsize = roundup(bufsize, mss); 3864 if (bufsize > sb_max) 3865 bufsize = sb_max; 3866 if (bufsize > so->so_snd.sb_hiwat) 3867 (void)sbreserve_locked(&so->so_snd, bufsize, so, NULL); 3868 } 3869 SOCKBUF_UNLOCK(&so->so_snd); 3870 /* 3871 * Sanity check: make sure that maxseg will be large 3872 * enough to allow some data on segments even if the 3873 * all the option space is used (40bytes). Otherwise 3874 * funny things may happen in tcp_output. 3875 * 3876 * XXXGL: shouldn't we reserve space for IP/IPv6 options? 3877 */ 3878 tp->t_maxseg = max(mss, 64); 3879 3880 SOCKBUF_LOCK(&so->so_rcv); 3881 if ((so->so_rcv.sb_hiwat == V_tcp_recvspace) && metrics.rmx_recvpipe) 3882 bufsize = metrics.rmx_recvpipe; 3883 else 3884 bufsize = so->so_rcv.sb_hiwat; 3885 if (bufsize > mss) { 3886 bufsize = roundup(bufsize, mss); 3887 if (bufsize > sb_max) 3888 bufsize = sb_max; 3889 if (bufsize > so->so_rcv.sb_hiwat) 3890 (void)sbreserve_locked(&so->so_rcv, bufsize, so, NULL); 3891 } 3892 SOCKBUF_UNLOCK(&so->so_rcv); 3893 3894 /* Check the interface for TSO capabilities. */ 3895 if (cap.ifcap & CSUM_TSO) { 3896 tp->t_flags |= TF_TSO; 3897 tp->t_tsomax = cap.tsomax; 3898 tp->t_tsomaxsegcount = cap.tsomaxsegcount; 3899 tp->t_tsomaxsegsize = cap.tsomaxsegsize; 3900 } 3901 } 3902 3903 /* 3904 * Determine the MSS option to send on an outgoing SYN. 3905 */ 3906 int 3907 tcp_mssopt(struct in_conninfo *inc) 3908 { 3909 int mss = 0; 3910 uint32_t thcmtu = 0; 3911 uint32_t maxmtu = 0; 3912 size_t min_protoh; 3913 3914 KASSERT(inc != NULL, ("tcp_mssopt with NULL in_conninfo pointer")); 3915 3916 #ifdef INET6 3917 if (inc->inc_flags & INC_ISIPV6) { 3918 mss = V_tcp_v6mssdflt; 3919 maxmtu = tcp_maxmtu6(inc, NULL); 3920 min_protoh = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 3921 } 3922 #endif 3923 #if defined(INET) && defined(INET6) 3924 else 3925 #endif 3926 #ifdef INET 3927 { 3928 mss = V_tcp_mssdflt; 3929 maxmtu = tcp_maxmtu(inc, NULL); 3930 min_protoh = sizeof(struct tcpiphdr); 3931 } 3932 #endif 3933 #if defined(INET6) || defined(INET) 3934 thcmtu = tcp_hc_getmtu(inc); /* IPv4 and IPv6 */ 3935 #endif 3936 3937 if (maxmtu && thcmtu) 3938 mss = min(maxmtu, thcmtu) - min_protoh; 3939 else if (maxmtu || thcmtu) 3940 mss = max(maxmtu, thcmtu) - min_protoh; 3941 3942 return (mss); 3943 } 3944 3945 void 3946 tcp_prr_partialack(struct tcpcb *tp, struct tcphdr *th) 3947 { 3948 int snd_cnt = 0, limit = 0, del_data = 0, pipe = 0; 3949 int maxseg = tcp_maxseg(tp); 3950 3951 INP_WLOCK_ASSERT(tp->t_inpcb); 3952 3953 tcp_timer_activate(tp, TT_REXMT, 0); 3954 tp->t_rtttime = 0; 3955 /* 3956 * Compute the amount of data that this ACK is indicating 3957 * (del_data) and an estimate of how many bytes are in the 3958 * network. 3959 */ 3960 del_data = tp->sackhint.delivered_data; 3961 if (V_tcp_do_rfc6675_pipe) 3962 pipe = tcp_compute_pipe(tp); 3963 else 3964 pipe = (tp->snd_nxt - tp->snd_fack) + tp->sackhint.sack_bytes_rexmit; 3965 tp->sackhint.prr_delivered += del_data; 3966 /* 3967 * Proportional Rate Reduction 3968 */ 3969 if (pipe >= tp->snd_ssthresh) { 3970 if (tp->sackhint.recover_fs == 0) 3971 tp->sackhint.recover_fs = 3972 imax(1, tp->snd_nxt - tp->snd_una); 3973 snd_cnt = howmany((long)tp->sackhint.prr_delivered * 3974 tp->snd_ssthresh, tp->sackhint.recover_fs) - 3975 tp->sackhint.prr_out; 3976 } else { 3977 if (V_tcp_do_prr_conservative) 3978 limit = tp->sackhint.prr_delivered - 3979 tp->sackhint.prr_out; 3980 else 3981 limit = imax(tp->sackhint.prr_delivered - 3982 tp->sackhint.prr_out, del_data) + 3983 maxseg; 3984 snd_cnt = imin((tp->snd_ssthresh - pipe), limit); 3985 } 3986 snd_cnt = imax(snd_cnt, 0) / maxseg; 3987 /* 3988 * Send snd_cnt new data into the network in response to this ack. 3989 * If there is going to be a SACK retransmission, adjust snd_cwnd 3990 * accordingly. 3991 */ 3992 tp->snd_cwnd = imax(maxseg, tp->snd_nxt - tp->snd_recover + 3993 tp->sackhint.sack_bytes_rexmit + (snd_cnt * maxseg)); 3994 tp->t_flags |= TF_ACKNOW; 3995 (void) tcp_output(tp); 3996 } 3997 3998 /* 3999 * On a partial ack arrives, force the retransmission of the 4000 * next unacknowledged segment. Do not clear tp->t_dupacks. 4001 * By setting snd_nxt to ti_ack, this forces retransmission timer to 4002 * be started again. 4003 */ 4004 void 4005 tcp_newreno_partial_ack(struct tcpcb *tp, struct tcphdr *th) 4006 { 4007 tcp_seq onxt = tp->snd_nxt; 4008 uint32_t ocwnd = tp->snd_cwnd; 4009 u_int maxseg = tcp_maxseg(tp); 4010 4011 INP_WLOCK_ASSERT(tp->t_inpcb); 4012 4013 tcp_timer_activate(tp, TT_REXMT, 0); 4014 tp->t_rtttime = 0; 4015 tp->snd_nxt = th->th_ack; 4016 /* 4017 * Set snd_cwnd to one segment beyond acknowledged offset. 4018 * (tp->snd_una has not yet been updated when this function is called.) 4019 */ 4020 tp->snd_cwnd = maxseg + BYTES_THIS_ACK(tp, th); 4021 tp->t_flags |= TF_ACKNOW; 4022 (void) tp->t_fb->tfb_tcp_output(tp); 4023 tp->snd_cwnd = ocwnd; 4024 if (SEQ_GT(onxt, tp->snd_nxt)) 4025 tp->snd_nxt = onxt; 4026 /* 4027 * Partial window deflation. Relies on fact that tp->snd_una 4028 * not updated yet. 4029 */ 4030 if (tp->snd_cwnd > BYTES_THIS_ACK(tp, th)) 4031 tp->snd_cwnd -= BYTES_THIS_ACK(tp, th); 4032 else 4033 tp->snd_cwnd = 0; 4034 tp->snd_cwnd += maxseg; 4035 } 4036 4037 int 4038 tcp_compute_pipe(struct tcpcb *tp) 4039 { 4040 return (tp->snd_max - tp->snd_una + 4041 tp->sackhint.sack_bytes_rexmit - 4042 tp->sackhint.sacked_bytes); 4043 } 4044 4045 uint32_t 4046 tcp_compute_initwnd(uint32_t maxseg) 4047 { 4048 /* 4049 * Calculate the Initial Window, also used as Restart Window 4050 * 4051 * RFC5681 Section 3.1 specifies the default conservative values. 4052 * RFC3390 specifies slightly more aggressive values. 4053 * RFC6928 increases it to ten segments. 4054 * Support for user specified value for initial flight size. 4055 */ 4056 if (V_tcp_initcwnd_segments) 4057 return min(V_tcp_initcwnd_segments * maxseg, 4058 max(2 * maxseg, V_tcp_initcwnd_segments * 1460)); 4059 else if (V_tcp_do_rfc3390) 4060 return min(4 * maxseg, max(2 * maxseg, 4380)); 4061 else { 4062 /* Per RFC5681 Section 3.1 */ 4063 if (maxseg > 2190) 4064 return (2 * maxseg); 4065 else if (maxseg > 1095) 4066 return (3 * maxseg); 4067 else 4068 return (4 * maxseg); 4069 } 4070 } 4071