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 <[email protected]> 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 #include <netinet/udp.h> 127 128 #include <netipsec/ipsec_support.h> 129 130 #include <machine/in_cksum.h> 131 132 #include <security/mac/mac_framework.h> 133 134 const int tcprexmtthresh = 3; 135 136 VNET_DEFINE(int, tcp_log_in_vain) = 0; 137 SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_in_vain, CTLFLAG_VNET | CTLFLAG_RW, 138 &VNET_NAME(tcp_log_in_vain), 0, 139 "Log all incoming TCP segments to closed ports"); 140 141 VNET_DEFINE(int, blackhole) = 0; 142 #define V_blackhole VNET(blackhole) 143 SYSCTL_INT(_net_inet_tcp, OID_AUTO, blackhole, CTLFLAG_VNET | CTLFLAG_RW, 144 &VNET_NAME(blackhole), 0, 145 "Do not send RST on segments to closed ports"); 146 147 VNET_DEFINE(int, tcp_delack_enabled) = 1; 148 SYSCTL_INT(_net_inet_tcp, OID_AUTO, delayed_ack, CTLFLAG_VNET | CTLFLAG_RW, 149 &VNET_NAME(tcp_delack_enabled), 0, 150 "Delay ACK to try and piggyback it onto a data packet"); 151 152 VNET_DEFINE(int, drop_synfin) = 0; 153 SYSCTL_INT(_net_inet_tcp, OID_AUTO, drop_synfin, CTLFLAG_VNET | CTLFLAG_RW, 154 &VNET_NAME(drop_synfin), 0, 155 "Drop TCP packets with SYN+FIN set"); 156 157 VNET_DEFINE(int, tcp_do_prr_conservative) = 0; 158 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_prr_conservative, CTLFLAG_VNET | CTLFLAG_RW, 159 &VNET_NAME(tcp_do_prr_conservative), 0, 160 "Do conservative Proportional Rate Reduction"); 161 162 VNET_DEFINE(int, tcp_do_prr) = 1; 163 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_prr, CTLFLAG_VNET | CTLFLAG_RW, 164 &VNET_NAME(tcp_do_prr), 1, 165 "Enable Proportional Rate Reduction per RFC 6937"); 166 167 VNET_DEFINE(int, tcp_do_newcwv) = 0; 168 SYSCTL_INT(_net_inet_tcp, OID_AUTO, newcwv, CTLFLAG_VNET | CTLFLAG_RW, 169 &VNET_NAME(tcp_do_newcwv), 0, 170 "Enable New Congestion Window Validation per RFC7661"); 171 172 VNET_DEFINE(int, tcp_do_rfc3042) = 1; 173 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3042, CTLFLAG_VNET | CTLFLAG_RW, 174 &VNET_NAME(tcp_do_rfc3042), 0, 175 "Enable RFC 3042 (Limited Transmit)"); 176 177 VNET_DEFINE(int, tcp_do_rfc3390) = 1; 178 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3390, CTLFLAG_VNET | CTLFLAG_RW, 179 &VNET_NAME(tcp_do_rfc3390), 0, 180 "Enable RFC 3390 (Increasing TCP's Initial Congestion Window)"); 181 182 VNET_DEFINE(int, tcp_initcwnd_segments) = 10; 183 SYSCTL_INT(_net_inet_tcp, OID_AUTO, initcwnd_segments, 184 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(tcp_initcwnd_segments), 0, 185 "Slow-start flight size (initial congestion window) in number of segments"); 186 187 VNET_DEFINE(int, tcp_do_rfc3465) = 1; 188 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3465, CTLFLAG_VNET | CTLFLAG_RW, 189 &VNET_NAME(tcp_do_rfc3465), 0, 190 "Enable RFC 3465 (Appropriate Byte Counting)"); 191 192 VNET_DEFINE(int, tcp_abc_l_var) = 2; 193 SYSCTL_INT(_net_inet_tcp, OID_AUTO, abc_l_var, CTLFLAG_VNET | CTLFLAG_RW, 194 &VNET_NAME(tcp_abc_l_var), 2, 195 "Cap the max cwnd increment during slow-start to this number of segments"); 196 197 static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, ecn, 198 CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 199 "TCP ECN"); 200 201 VNET_DEFINE(int, tcp_do_ecn) = 2; 202 SYSCTL_INT(_net_inet_tcp_ecn, OID_AUTO, enable, CTLFLAG_VNET | CTLFLAG_RW, 203 &VNET_NAME(tcp_do_ecn), 0, 204 "TCP ECN support"); 205 206 VNET_DEFINE(int, tcp_ecn_maxretries) = 1; 207 SYSCTL_INT(_net_inet_tcp_ecn, OID_AUTO, maxretries, CTLFLAG_VNET | CTLFLAG_RW, 208 &VNET_NAME(tcp_ecn_maxretries), 0, 209 "Max retries before giving up on ECN"); 210 211 VNET_DEFINE(int, tcp_insecure_syn) = 0; 212 SYSCTL_INT(_net_inet_tcp, OID_AUTO, insecure_syn, CTLFLAG_VNET | CTLFLAG_RW, 213 &VNET_NAME(tcp_insecure_syn), 0, 214 "Follow RFC793 instead of RFC5961 criteria for accepting SYN packets"); 215 216 VNET_DEFINE(int, tcp_insecure_rst) = 0; 217 SYSCTL_INT(_net_inet_tcp, OID_AUTO, insecure_rst, CTLFLAG_VNET | CTLFLAG_RW, 218 &VNET_NAME(tcp_insecure_rst), 0, 219 "Follow RFC793 instead of RFC5961 criteria for accepting RST packets"); 220 221 VNET_DEFINE(int, tcp_recvspace) = 1024*64; 222 #define V_tcp_recvspace VNET(tcp_recvspace) 223 SYSCTL_INT(_net_inet_tcp, TCPCTL_RECVSPACE, recvspace, CTLFLAG_VNET | CTLFLAG_RW, 224 &VNET_NAME(tcp_recvspace), 0, "Initial receive socket buffer size"); 225 226 VNET_DEFINE(int, tcp_do_autorcvbuf) = 1; 227 SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_auto, CTLFLAG_VNET | CTLFLAG_RW, 228 &VNET_NAME(tcp_do_autorcvbuf), 0, 229 "Enable automatic receive buffer sizing"); 230 231 VNET_DEFINE(int, tcp_autorcvbuf_max) = 2*1024*1024; 232 SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_max, CTLFLAG_VNET | CTLFLAG_RW, 233 &VNET_NAME(tcp_autorcvbuf_max), 0, 234 "Max size of automatic receive buffer"); 235 236 VNET_DEFINE(struct inpcbhead, tcb); 237 #define tcb6 tcb /* for KAME src sync over BSD*'s */ 238 VNET_DEFINE(struct inpcbinfo, tcbinfo); 239 240 /* 241 * TCP statistics are stored in an array of counter(9)s, which size matches 242 * size of struct tcpstat. TCP running connection count is a regular array. 243 */ 244 VNET_PCPUSTAT_DEFINE(struct tcpstat, tcpstat); 245 SYSCTL_VNET_PCPUSTAT(_net_inet_tcp, TCPCTL_STATS, stats, struct tcpstat, 246 tcpstat, "TCP statistics (struct tcpstat, netinet/tcp_var.h)"); 247 VNET_DEFINE(counter_u64_t, tcps_states[TCP_NSTATES]); 248 SYSCTL_COUNTER_U64_ARRAY(_net_inet_tcp, TCPCTL_STATES, states, CTLFLAG_RD | 249 CTLFLAG_VNET, &VNET_NAME(tcps_states)[0], TCP_NSTATES, 250 "TCP connection counts by TCP state"); 251 252 static void 253 tcp_vnet_init(const void *unused) 254 { 255 256 COUNTER_ARRAY_ALLOC(V_tcps_states, TCP_NSTATES, M_WAITOK); 257 VNET_PCPUSTAT_ALLOC(tcpstat, M_WAITOK); 258 } 259 VNET_SYSINIT(tcp_vnet_init, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY, 260 tcp_vnet_init, NULL); 261 262 #ifdef VIMAGE 263 static void 264 tcp_vnet_uninit(const void *unused) 265 { 266 267 COUNTER_ARRAY_FREE(V_tcps_states, TCP_NSTATES); 268 VNET_PCPUSTAT_FREE(tcpstat); 269 } 270 VNET_SYSUNINIT(tcp_vnet_uninit, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY, 271 tcp_vnet_uninit, NULL); 272 #endif /* VIMAGE */ 273 274 /* 275 * Kernel module interface for updating tcpstat. The first argument is an index 276 * into tcpstat treated as an array. 277 */ 278 void 279 kmod_tcpstat_add(int statnum, int val) 280 { 281 282 counter_u64_add(VNET(tcpstat)[statnum], val); 283 } 284 285 #ifdef TCP_HHOOK 286 /* 287 * Wrapper for the TCP established input helper hook. 288 */ 289 void 290 hhook_run_tcp_est_in(struct tcpcb *tp, struct tcphdr *th, struct tcpopt *to) 291 { 292 struct tcp_hhook_data hhook_data; 293 294 if (V_tcp_hhh[HHOOK_TCP_EST_IN]->hhh_nhooks > 0) { 295 hhook_data.tp = tp; 296 hhook_data.th = th; 297 hhook_data.to = to; 298 299 hhook_run_hooks(V_tcp_hhh[HHOOK_TCP_EST_IN], &hhook_data, 300 tp->osd); 301 } 302 } 303 #endif 304 305 /* 306 * CC wrapper hook functions 307 */ 308 void 309 cc_ack_received(struct tcpcb *tp, struct tcphdr *th, uint16_t nsegs, 310 uint16_t type) 311 { 312 #ifdef STATS 313 int32_t gput; 314 #endif 315 316 INP_WLOCK_ASSERT(tp->t_inpcb); 317 318 tp->ccv->nsegs = nsegs; 319 tp->ccv->bytes_this_ack = BYTES_THIS_ACK(tp, th); 320 if ((!V_tcp_do_newcwv && (tp->snd_cwnd <= tp->snd_wnd)) || 321 (V_tcp_do_newcwv && (tp->snd_cwnd <= tp->snd_wnd) && 322 (tp->snd_cwnd < (tcp_compute_pipe(tp) * 2)))) 323 tp->ccv->flags |= CCF_CWND_LIMITED; 324 else 325 tp->ccv->flags &= ~CCF_CWND_LIMITED; 326 327 if (type == CC_ACK) { 328 #ifdef STATS 329 stats_voi_update_abs_s32(tp->t_stats, VOI_TCP_CALCFRWINDIFF, 330 ((int32_t)tp->snd_cwnd) - tp->snd_wnd); 331 if (!IN_RECOVERY(tp->t_flags)) 332 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_ACKLEN, 333 tp->ccv->bytes_this_ack / (tcp_maxseg(tp) * nsegs)); 334 if ((tp->t_flags & TF_GPUTINPROG) && 335 SEQ_GEQ(th->th_ack, tp->gput_ack)) { 336 /* 337 * Compute goodput in bits per millisecond. 338 */ 339 gput = (((int64_t)(th->th_ack - tp->gput_seq)) << 3) / 340 max(1, tcp_ts_getticks() - tp->gput_ts); 341 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_GPUT, 342 gput); 343 /* 344 * XXXLAS: This is a temporary hack, and should be 345 * chained off VOI_TCP_GPUT when stats(9) grows an API 346 * to deal with chained VOIs. 347 */ 348 if (tp->t_stats_gput_prev > 0) 349 stats_voi_update_abs_s32(tp->t_stats, 350 VOI_TCP_GPUT_ND, 351 ((gput - tp->t_stats_gput_prev) * 100) / 352 tp->t_stats_gput_prev); 353 tp->t_flags &= ~TF_GPUTINPROG; 354 tp->t_stats_gput_prev = gput; 355 } 356 #endif /* STATS */ 357 if (tp->snd_cwnd > tp->snd_ssthresh) { 358 tp->t_bytes_acked += tp->ccv->bytes_this_ack; 359 if (tp->t_bytes_acked >= tp->snd_cwnd) { 360 tp->t_bytes_acked -= tp->snd_cwnd; 361 tp->ccv->flags |= CCF_ABC_SENTAWND; 362 } 363 } else { 364 tp->ccv->flags &= ~CCF_ABC_SENTAWND; 365 tp->t_bytes_acked = 0; 366 } 367 } 368 369 if (CC_ALGO(tp)->ack_received != NULL) { 370 /* XXXLAS: Find a way to live without this */ 371 tp->ccv->curack = th->th_ack; 372 CC_ALGO(tp)->ack_received(tp->ccv, type); 373 } 374 #ifdef STATS 375 stats_voi_update_abs_ulong(tp->t_stats, VOI_TCP_LCWIN, tp->snd_cwnd); 376 #endif 377 } 378 379 void 380 cc_conn_init(struct tcpcb *tp) 381 { 382 struct hc_metrics_lite metrics; 383 struct inpcb *inp = tp->t_inpcb; 384 u_int maxseg; 385 int rtt; 386 387 INP_WLOCK_ASSERT(tp->t_inpcb); 388 389 tcp_hc_get(&inp->inp_inc, &metrics); 390 maxseg = tcp_maxseg(tp); 391 392 if (tp->t_srtt == 0 && (rtt = metrics.rmx_rtt)) { 393 tp->t_srtt = rtt; 394 tp->t_rttbest = tp->t_srtt + TCP_RTT_SCALE; 395 TCPSTAT_INC(tcps_usedrtt); 396 if (metrics.rmx_rttvar) { 397 tp->t_rttvar = metrics.rmx_rttvar; 398 TCPSTAT_INC(tcps_usedrttvar); 399 } else { 400 /* default variation is +- 1 rtt */ 401 tp->t_rttvar = 402 tp->t_srtt * TCP_RTTVAR_SCALE / TCP_RTT_SCALE; 403 } 404 TCPT_RANGESET(tp->t_rxtcur, 405 ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1, 406 tp->t_rttmin, TCPTV_REXMTMAX); 407 } 408 if (metrics.rmx_ssthresh) { 409 /* 410 * There's some sort of gateway or interface 411 * buffer limit on the path. Use this to set 412 * the slow start threshold, but set the 413 * threshold to no less than 2*mss. 414 */ 415 tp->snd_ssthresh = max(2 * maxseg, metrics.rmx_ssthresh); 416 TCPSTAT_INC(tcps_usedssthresh); 417 } 418 419 /* 420 * Set the initial slow-start flight size. 421 * 422 * If a SYN or SYN/ACK was lost and retransmitted, we have to 423 * reduce the initial CWND to one segment as congestion is likely 424 * requiring us to be cautious. 425 */ 426 if (tp->snd_cwnd == 1) 427 tp->snd_cwnd = maxseg; /* SYN(-ACK) lost */ 428 else 429 tp->snd_cwnd = tcp_compute_initwnd(maxseg); 430 431 if (CC_ALGO(tp)->conn_init != NULL) 432 CC_ALGO(tp)->conn_init(tp->ccv); 433 } 434 435 void inline 436 cc_cong_signal(struct tcpcb *tp, struct tcphdr *th, uint32_t type) 437 { 438 INP_WLOCK_ASSERT(tp->t_inpcb); 439 440 #ifdef STATS 441 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_CSIG, type); 442 #endif 443 444 switch(type) { 445 case CC_NDUPACK: 446 if (!IN_FASTRECOVERY(tp->t_flags)) { 447 tp->snd_recover = tp->snd_max; 448 if (tp->t_flags2 & TF2_ECN_PERMIT) 449 tp->t_flags2 |= TF2_ECN_SND_CWR; 450 } 451 break; 452 case CC_ECN: 453 if (!IN_CONGRECOVERY(tp->t_flags) || 454 /* 455 * Allow ECN reaction on ACK to CWR, if 456 * that data segment was also CE marked. 457 */ 458 SEQ_GEQ(th->th_ack, tp->snd_recover)) { 459 EXIT_CONGRECOVERY(tp->t_flags); 460 TCPSTAT_INC(tcps_ecn_rcwnd); 461 tp->snd_recover = tp->snd_max + 1; 462 if (tp->t_flags2 & TF2_ECN_PERMIT) 463 tp->t_flags2 |= TF2_ECN_SND_CWR; 464 } 465 break; 466 case CC_RTO: 467 tp->t_dupacks = 0; 468 tp->t_bytes_acked = 0; 469 EXIT_RECOVERY(tp->t_flags); 470 if (tp->t_flags2 & TF2_ECN_PERMIT) 471 tp->t_flags2 |= TF2_ECN_SND_CWR; 472 break; 473 case CC_RTO_ERR: 474 TCPSTAT_INC(tcps_sndrexmitbad); 475 /* RTO was unnecessary, so reset everything. */ 476 tp->snd_cwnd = tp->snd_cwnd_prev; 477 tp->snd_ssthresh = tp->snd_ssthresh_prev; 478 tp->snd_recover = tp->snd_recover_prev; 479 if (tp->t_flags & TF_WASFRECOVERY) 480 ENTER_FASTRECOVERY(tp->t_flags); 481 if (tp->t_flags & TF_WASCRECOVERY) 482 ENTER_CONGRECOVERY(tp->t_flags); 483 tp->snd_nxt = tp->snd_max; 484 tp->t_flags &= ~TF_PREVVALID; 485 tp->t_badrxtwin = 0; 486 break; 487 } 488 489 if (CC_ALGO(tp)->cong_signal != NULL) { 490 if (th != NULL) 491 tp->ccv->curack = th->th_ack; 492 CC_ALGO(tp)->cong_signal(tp->ccv, type); 493 } 494 } 495 496 void inline 497 cc_post_recovery(struct tcpcb *tp, struct tcphdr *th) 498 { 499 INP_WLOCK_ASSERT(tp->t_inpcb); 500 501 /* XXXLAS: KASSERT that we're in recovery? */ 502 503 if (CC_ALGO(tp)->post_recovery != NULL) { 504 tp->ccv->curack = th->th_ack; 505 CC_ALGO(tp)->post_recovery(tp->ccv); 506 } 507 /* XXXLAS: EXIT_RECOVERY ? */ 508 tp->t_bytes_acked = 0; 509 tp->sackhint.prr_out = 0; 510 } 511 512 /* 513 * Indicate whether this ack should be delayed. We can delay the ack if 514 * following conditions are met: 515 * - There is no delayed ack timer in progress. 516 * - Our last ack wasn't a 0-sized window. We never want to delay 517 * the ack that opens up a 0-sized window. 518 * - LRO wasn't used for this segment. We make sure by checking that the 519 * segment size is not larger than the MSS. 520 */ 521 #define DELAY_ACK(tp, tlen) \ 522 ((!tcp_timer_active(tp, TT_DELACK) && \ 523 (tp->t_flags & TF_RXWIN0SENT) == 0) && \ 524 (tlen <= tp->t_maxseg) && \ 525 (V_tcp_delack_enabled || (tp->t_flags & TF_NEEDSYN))) 526 527 void inline 528 cc_ecnpkt_handler(struct tcpcb *tp, struct tcphdr *th, uint8_t iptos) 529 { 530 INP_WLOCK_ASSERT(tp->t_inpcb); 531 532 if (CC_ALGO(tp)->ecnpkt_handler != NULL) { 533 switch (iptos & IPTOS_ECN_MASK) { 534 case IPTOS_ECN_CE: 535 tp->ccv->flags |= CCF_IPHDR_CE; 536 break; 537 case IPTOS_ECN_ECT0: 538 /* FALLTHROUGH */ 539 case IPTOS_ECN_ECT1: 540 /* FALLTHROUGH */ 541 case IPTOS_ECN_NOTECT: 542 tp->ccv->flags &= ~CCF_IPHDR_CE; 543 break; 544 } 545 546 if (th->th_flags & TH_CWR) 547 tp->ccv->flags |= CCF_TCPHDR_CWR; 548 else 549 tp->ccv->flags &= ~CCF_TCPHDR_CWR; 550 551 CC_ALGO(tp)->ecnpkt_handler(tp->ccv); 552 553 if (tp->ccv->flags & CCF_ACKNOW) { 554 tcp_timer_activate(tp, TT_DELACK, tcp_delacktime); 555 tp->t_flags |= TF_ACKNOW; 556 } 557 } 558 } 559 560 /* 561 * TCP input handling is split into multiple parts: 562 * tcp6_input is a thin wrapper around tcp_input for the extended 563 * ip6_protox[] call format in ip6_input 564 * tcp_input handles primary segment validation, inpcb lookup and 565 * SYN processing on listen sockets 566 * tcp_do_segment processes the ACK and text of the segment for 567 * establishing, established and closing connections 568 */ 569 #ifdef INET6 570 int 571 tcp6_input_with_port(struct mbuf **mp, int *offp, int proto, uint16_t port) 572 { 573 struct mbuf *m; 574 struct in6_ifaddr *ia6; 575 struct ip6_hdr *ip6; 576 577 m = *mp; 578 if (m->m_len < *offp + sizeof(struct tcphdr)) { 579 m = m_pullup(m, *offp + sizeof(struct tcphdr)); 580 if (m == NULL) { 581 *mp = m; 582 TCPSTAT_INC(tcps_rcvshort); 583 return (IPPROTO_DONE); 584 } 585 } 586 587 /* 588 * draft-itojun-ipv6-tcp-to-anycast 589 * better place to put this in? 590 */ 591 ip6 = mtod(m, struct ip6_hdr *); 592 ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */, false); 593 if (ia6 && (ia6->ia6_flags & IN6_IFF_ANYCAST)) { 594 icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR, 595 (caddr_t)&ip6->ip6_dst - (caddr_t)ip6); 596 *mp = NULL; 597 return (IPPROTO_DONE); 598 } 599 600 *mp = m; 601 return (tcp_input_with_port(mp, offp, proto, port)); 602 } 603 604 int 605 tcp6_input(struct mbuf **mp, int *offp, int proto) 606 { 607 608 return(tcp6_input_with_port(mp, offp, proto, 0)); 609 } 610 #endif /* INET6 */ 611 612 int 613 tcp_input_with_port(struct mbuf **mp, int *offp, int proto, uint16_t port) 614 { 615 struct mbuf *m = *mp; 616 struct tcphdr *th = NULL; 617 struct ip *ip = NULL; 618 struct inpcb *inp = NULL; 619 struct tcpcb *tp = NULL; 620 struct socket *so = NULL; 621 u_char *optp = NULL; 622 int off0; 623 int optlen = 0; 624 #ifdef INET 625 int len; 626 uint8_t ipttl; 627 #endif 628 int tlen = 0, off; 629 int drop_hdrlen; 630 int thflags; 631 int rstreason = 0; /* For badport_bandlim accounting purposes */ 632 int lookupflag; 633 uint8_t iptos; 634 struct m_tag *fwd_tag = NULL; 635 #ifdef INET6 636 struct ip6_hdr *ip6 = NULL; 637 int isipv6; 638 #else 639 const void *ip6 = NULL; 640 #endif /* INET6 */ 641 struct tcpopt to; /* options in this segment */ 642 char *s = NULL; /* address and port logging */ 643 #ifdef TCPDEBUG 644 /* 645 * The size of tcp_saveipgen must be the size of the max ip header, 646 * now IPv6. 647 */ 648 u_char tcp_saveipgen[IP6_HDR_LEN]; 649 struct tcphdr tcp_savetcp; 650 short ostate = 0; 651 #endif 652 653 NET_EPOCH_ASSERT(); 654 655 #ifdef INET6 656 isipv6 = (mtod(m, struct ip *)->ip_v == 6) ? 1 : 0; 657 #endif 658 659 off0 = *offp; 660 m = *mp; 661 *mp = NULL; 662 to.to_flags = 0; 663 TCPSTAT_INC(tcps_rcvtotal); 664 665 #ifdef INET6 666 if (isipv6) { 667 ip6 = mtod(m, struct ip6_hdr *); 668 th = (struct tcphdr *)((caddr_t)ip6 + off0); 669 tlen = sizeof(*ip6) + ntohs(ip6->ip6_plen) - off0; 670 if (port) 671 goto skip6_csum; 672 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID_IPV6) { 673 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 674 th->th_sum = m->m_pkthdr.csum_data; 675 else 676 th->th_sum = in6_cksum_pseudo(ip6, tlen, 677 IPPROTO_TCP, m->m_pkthdr.csum_data); 678 th->th_sum ^= 0xffff; 679 } else 680 th->th_sum = in6_cksum(m, IPPROTO_TCP, off0, tlen); 681 if (th->th_sum) { 682 TCPSTAT_INC(tcps_rcvbadsum); 683 goto drop; 684 } 685 skip6_csum: 686 /* 687 * Be proactive about unspecified IPv6 address in source. 688 * As we use all-zero to indicate unbounded/unconnected pcb, 689 * unspecified IPv6 address can be used to confuse us. 690 * 691 * Note that packets with unspecified IPv6 destination is 692 * already dropped in ip6_input. 693 */ 694 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 695 /* XXX stat */ 696 goto drop; 697 } 698 iptos = IPV6_TRAFFIC_CLASS(ip6); 699 } 700 #endif 701 #if defined(INET) && defined(INET6) 702 else 703 #endif 704 #ifdef INET 705 { 706 /* 707 * Get IP and TCP header together in first mbuf. 708 * Note: IP leaves IP header in first mbuf. 709 */ 710 if (off0 > sizeof (struct ip)) { 711 ip_stripoptions(m); 712 off0 = sizeof(struct ip); 713 } 714 if (m->m_len < sizeof (struct tcpiphdr)) { 715 if ((m = m_pullup(m, sizeof (struct tcpiphdr))) 716 == NULL) { 717 TCPSTAT_INC(tcps_rcvshort); 718 return (IPPROTO_DONE); 719 } 720 } 721 ip = mtod(m, struct ip *); 722 th = (struct tcphdr *)((caddr_t)ip + off0); 723 tlen = ntohs(ip->ip_len) - off0; 724 725 iptos = ip->ip_tos; 726 if (port) 727 goto skip_csum; 728 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) { 729 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 730 th->th_sum = m->m_pkthdr.csum_data; 731 else 732 th->th_sum = in_pseudo(ip->ip_src.s_addr, 733 ip->ip_dst.s_addr, 734 htonl(m->m_pkthdr.csum_data + tlen + 735 IPPROTO_TCP)); 736 th->th_sum ^= 0xffff; 737 } else { 738 struct ipovly *ipov = (struct ipovly *)ip; 739 740 /* 741 * Checksum extended TCP header and data. 742 */ 743 len = off0 + tlen; 744 ipttl = ip->ip_ttl; 745 bzero(ipov->ih_x1, sizeof(ipov->ih_x1)); 746 ipov->ih_len = htons(tlen); 747 th->th_sum = in_cksum(m, len); 748 /* Reset length for SDT probes. */ 749 ip->ip_len = htons(len); 750 /* Reset TOS bits */ 751 ip->ip_tos = iptos; 752 /* Re-initialization for later version check */ 753 ip->ip_ttl = ipttl; 754 ip->ip_v = IPVERSION; 755 ip->ip_hl = off0 >> 2; 756 } 757 skip_csum: 758 if (th->th_sum && (port == 0)) { 759 TCPSTAT_INC(tcps_rcvbadsum); 760 goto drop; 761 } 762 } 763 #endif /* INET */ 764 765 /* 766 * Check that TCP offset makes sense, 767 * pull out TCP options and adjust length. XXX 768 */ 769 off = th->th_off << 2; 770 if (off < sizeof (struct tcphdr) || off > tlen) { 771 TCPSTAT_INC(tcps_rcvbadoff); 772 goto drop; 773 } 774 tlen -= off; /* tlen is used instead of ti->ti_len */ 775 if (off > sizeof (struct tcphdr)) { 776 #ifdef INET6 777 if (isipv6) { 778 if (m->m_len < off0 + off) { 779 m = m_pullup(m, off0 + off); 780 if (m == NULL) { 781 TCPSTAT_INC(tcps_rcvshort); 782 return (IPPROTO_DONE); 783 } 784 } 785 ip6 = mtod(m, struct ip6_hdr *); 786 th = (struct tcphdr *)((caddr_t)ip6 + off0); 787 } 788 #endif 789 #if defined(INET) && defined(INET6) 790 else 791 #endif 792 #ifdef INET 793 { 794 if (m->m_len < sizeof(struct ip) + off) { 795 if ((m = m_pullup(m, sizeof (struct ip) + off)) 796 == NULL) { 797 TCPSTAT_INC(tcps_rcvshort); 798 return (IPPROTO_DONE); 799 } 800 ip = mtod(m, struct ip *); 801 th = (struct tcphdr *)((caddr_t)ip + off0); 802 } 803 } 804 #endif 805 optlen = off - sizeof (struct tcphdr); 806 optp = (u_char *)(th + 1); 807 } 808 thflags = th->th_flags; 809 810 /* 811 * Convert TCP protocol specific fields to host format. 812 */ 813 tcp_fields_to_host(th); 814 815 /* 816 * Delay dropping TCP, IP headers, IPv6 ext headers, and TCP options. 817 */ 818 drop_hdrlen = off0 + off; 819 820 /* 821 * Grab info from PACKET_TAG_IPFORWARD tag prepended to the chain. 822 */ 823 if ( 824 #ifdef INET6 825 (isipv6 && (m->m_flags & M_IP6_NEXTHOP)) 826 #ifdef INET 827 || (!isipv6 && (m->m_flags & M_IP_NEXTHOP)) 828 #endif 829 #endif 830 #if defined(INET) && !defined(INET6) 831 (m->m_flags & M_IP_NEXTHOP) 832 #endif 833 ) 834 fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL); 835 836 /* 837 * For initial SYN packets arriving on listening socket, 838 * we don't need write lock. 839 */ 840 lookupflag = (thflags & (TH_ACK|TH_SYN)) == TH_SYN ? 841 INPLOOKUP_RLOCKLISTEN : INPLOOKUP_WLOCKPCB; 842 findpcb: 843 #ifdef INET6 844 if (isipv6 && fwd_tag != NULL) { 845 struct sockaddr_in6 *next_hop6; 846 847 next_hop6 = (struct sockaddr_in6 *)(fwd_tag + 1); 848 /* 849 * Transparently forwarded. Pretend to be the destination. 850 * Already got one like this? 851 */ 852 inp = in6_pcblookup_mbuf(&V_tcbinfo, 853 &ip6->ip6_src, th->th_sport, &ip6->ip6_dst, th->th_dport, 854 lookupflag, m->m_pkthdr.rcvif, m); 855 if (!inp) { 856 /* 857 * It's new. Try to find the ambushing socket. 858 * Because we've rewritten the destination address, 859 * any hardware-generated hash is ignored. 860 */ 861 inp = in6_pcblookup(&V_tcbinfo, &ip6->ip6_src, 862 th->th_sport, &next_hop6->sin6_addr, 863 next_hop6->sin6_port ? ntohs(next_hop6->sin6_port) : 864 th->th_dport, INPLOOKUP_WILDCARD | lookupflag, 865 m->m_pkthdr.rcvif); 866 } 867 } else if (isipv6) { 868 inp = in6_pcblookup_mbuf(&V_tcbinfo, &ip6->ip6_src, 869 th->th_sport, &ip6->ip6_dst, th->th_dport, 870 INPLOOKUP_WILDCARD | lookupflag, m->m_pkthdr.rcvif, m); 871 } 872 #endif /* INET6 */ 873 #if defined(INET6) && defined(INET) 874 else 875 #endif 876 #ifdef INET 877 if (fwd_tag != NULL) { 878 struct sockaddr_in *next_hop; 879 880 next_hop = (struct sockaddr_in *)(fwd_tag+1); 881 /* 882 * Transparently forwarded. Pretend to be the destination. 883 * already got one like this? 884 */ 885 inp = in_pcblookup_mbuf(&V_tcbinfo, ip->ip_src, th->th_sport, 886 ip->ip_dst, th->th_dport, lookupflag, m->m_pkthdr.rcvif, m); 887 if (!inp) { 888 /* 889 * It's new. Try to find the ambushing socket. 890 * Because we've rewritten the destination address, 891 * any hardware-generated hash is ignored. 892 */ 893 inp = in_pcblookup(&V_tcbinfo, ip->ip_src, 894 th->th_sport, next_hop->sin_addr, 895 next_hop->sin_port ? ntohs(next_hop->sin_port) : 896 th->th_dport, INPLOOKUP_WILDCARD | lookupflag, 897 m->m_pkthdr.rcvif); 898 } 899 } else 900 inp = in_pcblookup_mbuf(&V_tcbinfo, ip->ip_src, 901 th->th_sport, ip->ip_dst, th->th_dport, 902 INPLOOKUP_WILDCARD | lookupflag, m->m_pkthdr.rcvif, m); 903 #endif /* INET */ 904 905 /* 906 * If the INPCB does not exist then all data in the incoming 907 * segment is discarded and an appropriate RST is sent back. 908 * XXX MRT Send RST using which routing table? 909 */ 910 if (inp == NULL) { 911 /* 912 * Log communication attempts to ports that are not 913 * in use. 914 */ 915 if ((V_tcp_log_in_vain == 1 && (thflags & TH_SYN)) || 916 V_tcp_log_in_vain == 2) { 917 if ((s = tcp_log_vain(NULL, th, (void *)ip, ip6))) 918 log(LOG_INFO, "%s; %s: Connection attempt " 919 "to closed port\n", s, __func__); 920 } 921 /* 922 * When blackholing do not respond with a RST but 923 * completely ignore the segment and drop it. 924 */ 925 if ((V_blackhole == 1 && (thflags & TH_SYN)) || 926 V_blackhole == 2) 927 goto dropunlock; 928 929 rstreason = BANDLIM_RST_CLOSEDPORT; 930 goto dropwithreset; 931 } 932 INP_LOCK_ASSERT(inp); 933 /* 934 * While waiting for inp lock during the lookup, another thread 935 * can have dropped the inpcb, in which case we need to loop back 936 * and try to find a new inpcb to deliver to. 937 */ 938 if (inp->inp_flags & INP_DROPPED) { 939 INP_UNLOCK(inp); 940 inp = NULL; 941 goto findpcb; 942 } 943 if ((inp->inp_flowtype == M_HASHTYPE_NONE) && 944 (M_HASHTYPE_GET(m) != M_HASHTYPE_NONE) && 945 ((inp->inp_socket == NULL) || 946 (inp->inp_socket->so_options & SO_ACCEPTCONN) == 0)) { 947 inp->inp_flowid = m->m_pkthdr.flowid; 948 inp->inp_flowtype = M_HASHTYPE_GET(m); 949 } 950 #if defined(IPSEC) || defined(IPSEC_SUPPORT) 951 #ifdef INET6 952 if (isipv6 && IPSEC_ENABLED(ipv6) && 953 IPSEC_CHECK_POLICY(ipv6, m, inp) != 0) { 954 goto dropunlock; 955 } 956 #ifdef INET 957 else 958 #endif 959 #endif /* INET6 */ 960 #ifdef INET 961 if (IPSEC_ENABLED(ipv4) && 962 IPSEC_CHECK_POLICY(ipv4, m, inp) != 0) { 963 goto dropunlock; 964 } 965 #endif /* INET */ 966 #endif /* IPSEC */ 967 968 /* 969 * Check the minimum TTL for socket. 970 */ 971 if (inp->inp_ip_minttl != 0) { 972 #ifdef INET6 973 if (isipv6) { 974 if (inp->inp_ip_minttl > ip6->ip6_hlim) 975 goto dropunlock; 976 } else 977 #endif 978 if (inp->inp_ip_minttl > ip->ip_ttl) 979 goto dropunlock; 980 } 981 982 /* 983 * A previous connection in TIMEWAIT state is supposed to catch stray 984 * or duplicate segments arriving late. If this segment was a 985 * legitimate new connection attempt, the old INPCB gets removed and 986 * we can try again to find a listening socket. 987 * 988 * At this point, due to earlier optimism, we may hold only an inpcb 989 * lock, and not the inpcbinfo write lock. If so, we need to try to 990 * acquire it, or if that fails, acquire a reference on the inpcb, 991 * drop all locks, acquire a global write lock, and then re-acquire 992 * the inpcb lock. We may at that point discover that another thread 993 * has tried to free the inpcb, in which case we need to loop back 994 * and try to find a new inpcb to deliver to. 995 * 996 * XXXRW: It may be time to rethink timewait locking. 997 */ 998 if (inp->inp_flags & INP_TIMEWAIT) { 999 tcp_dooptions(&to, optp, optlen, 1000 (thflags & TH_SYN) ? TO_SYN : 0); 1001 /* 1002 * NB: tcp_twcheck unlocks the INP and frees the mbuf. 1003 */ 1004 if (tcp_twcheck(inp, &to, th, m, tlen)) 1005 goto findpcb; 1006 return (IPPROTO_DONE); 1007 } 1008 /* 1009 * The TCPCB may no longer exist if the connection is winding 1010 * down or it is in the CLOSED state. Either way we drop the 1011 * segment and send an appropriate response. 1012 */ 1013 tp = intotcpcb(inp); 1014 if (tp == NULL || tp->t_state == TCPS_CLOSED) { 1015 rstreason = BANDLIM_RST_CLOSEDPORT; 1016 goto dropwithreset; 1017 } 1018 1019 if ((tp->t_port != port) && (tp->t_state > TCPS_LISTEN)) { 1020 rstreason = BANDLIM_RST_CLOSEDPORT; 1021 goto dropwithreset; 1022 } 1023 1024 #ifdef TCP_OFFLOAD 1025 if (tp->t_flags & TF_TOE) { 1026 tcp_offload_input(tp, m); 1027 m = NULL; /* consumed by the TOE driver */ 1028 goto dropunlock; 1029 } 1030 #endif 1031 1032 #ifdef MAC 1033 if (mac_inpcb_check_deliver(inp, m)) 1034 goto dropunlock; 1035 #endif 1036 so = inp->inp_socket; 1037 KASSERT(so != NULL, ("%s: so == NULL", __func__)); 1038 #ifdef TCPDEBUG 1039 if (so->so_options & SO_DEBUG) { 1040 ostate = tp->t_state; 1041 #ifdef INET6 1042 if (isipv6) { 1043 bcopy((char *)ip6, (char *)tcp_saveipgen, sizeof(*ip6)); 1044 } else 1045 #endif 1046 bcopy((char *)ip, (char *)tcp_saveipgen, sizeof(*ip)); 1047 tcp_savetcp = *th; 1048 } 1049 #endif /* TCPDEBUG */ 1050 /* 1051 * When the socket is accepting connections (the INPCB is in LISTEN 1052 * state) we look into the SYN cache if this is a new connection 1053 * attempt or the completion of a previous one. 1054 */ 1055 KASSERT(tp->t_state == TCPS_LISTEN || !(so->so_options & SO_ACCEPTCONN), 1056 ("%s: so accepting but tp %p not listening", __func__, tp)); 1057 if (tp->t_state == TCPS_LISTEN && (so->so_options & SO_ACCEPTCONN)) { 1058 struct in_conninfo inc; 1059 1060 bzero(&inc, sizeof(inc)); 1061 #ifdef INET6 1062 if (isipv6) { 1063 inc.inc_flags |= INC_ISIPV6; 1064 if (inp->inp_inc.inc_flags & INC_IPV6MINMTU) 1065 inc.inc_flags |= INC_IPV6MINMTU; 1066 inc.inc6_faddr = ip6->ip6_src; 1067 inc.inc6_laddr = ip6->ip6_dst; 1068 } else 1069 #endif 1070 { 1071 inc.inc_faddr = ip->ip_src; 1072 inc.inc_laddr = ip->ip_dst; 1073 } 1074 inc.inc_fport = th->th_sport; 1075 inc.inc_lport = th->th_dport; 1076 inc.inc_fibnum = so->so_fibnum; 1077 1078 /* 1079 * Check for an existing connection attempt in syncache if 1080 * the flag is only ACK. A successful lookup creates a new 1081 * socket appended to the listen queue in SYN_RECEIVED state. 1082 */ 1083 if ((thflags & (TH_RST|TH_ACK|TH_SYN)) == TH_ACK) { 1084 /* 1085 * Parse the TCP options here because 1086 * syncookies need access to the reflected 1087 * timestamp. 1088 */ 1089 tcp_dooptions(&to, optp, optlen, 0); 1090 /* 1091 * NB: syncache_expand() doesn't unlock 1092 * inp and tcpinfo locks. 1093 */ 1094 rstreason = syncache_expand(&inc, &to, th, &so, m, port); 1095 if (rstreason < 0) { 1096 /* 1097 * A failing TCP MD5 signature comparison 1098 * must result in the segment being dropped 1099 * and must not produce any response back 1100 * to the sender. 1101 */ 1102 goto dropunlock; 1103 } else if (rstreason == 0) { 1104 /* 1105 * No syncache entry or ACK was not 1106 * for our SYN/ACK. Send a RST. 1107 * NB: syncache did its own logging 1108 * of the failure cause. 1109 */ 1110 rstreason = BANDLIM_RST_OPENPORT; 1111 goto dropwithreset; 1112 } 1113 tfo_socket_result: 1114 if (so == NULL) { 1115 /* 1116 * We completed the 3-way handshake 1117 * but could not allocate a socket 1118 * either due to memory shortage, 1119 * listen queue length limits or 1120 * global socket limits. Send RST 1121 * or wait and have the remote end 1122 * retransmit the ACK for another 1123 * try. 1124 */ 1125 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1126 log(LOG_DEBUG, "%s; %s: Listen socket: " 1127 "Socket allocation failed due to " 1128 "limits or memory shortage, %s\n", 1129 s, __func__, 1130 V_tcp_sc_rst_sock_fail ? 1131 "sending RST" : "try again"); 1132 if (V_tcp_sc_rst_sock_fail) { 1133 rstreason = BANDLIM_UNLIMITED; 1134 goto dropwithreset; 1135 } else 1136 goto dropunlock; 1137 } 1138 /* 1139 * Socket is created in state SYN_RECEIVED. 1140 * Unlock the listen socket, lock the newly 1141 * created socket and update the tp variable. 1142 * If we came here via jump to tfo_socket_result, 1143 * then listening socket is read-locked. 1144 */ 1145 INP_UNLOCK(inp); /* listen socket */ 1146 inp = sotoinpcb(so); 1147 /* 1148 * New connection inpcb is already locked by 1149 * syncache_expand(). 1150 */ 1151 INP_WLOCK_ASSERT(inp); 1152 tp = intotcpcb(inp); 1153 KASSERT(tp->t_state == TCPS_SYN_RECEIVED, 1154 ("%s: ", __func__)); 1155 /* 1156 * Process the segment and the data it 1157 * contains. tcp_do_segment() consumes 1158 * the mbuf chain and unlocks the inpcb. 1159 */ 1160 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1161 tp->t_fb->tfb_tcp_do_segment(m, th, so, tp, drop_hdrlen, tlen, 1162 iptos); 1163 return (IPPROTO_DONE); 1164 } 1165 /* 1166 * Segment flag validation for new connection attempts: 1167 * 1168 * Our (SYN|ACK) response was rejected. 1169 * Check with syncache and remove entry to prevent 1170 * retransmits. 1171 * 1172 * NB: syncache_chkrst does its own logging of failure 1173 * causes. 1174 */ 1175 if (thflags & TH_RST) { 1176 syncache_chkrst(&inc, th, m, port); 1177 goto dropunlock; 1178 } 1179 /* 1180 * We can't do anything without SYN. 1181 */ 1182 if ((thflags & TH_SYN) == 0) { 1183 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1184 log(LOG_DEBUG, "%s; %s: Listen socket: " 1185 "SYN is missing, segment ignored\n", 1186 s, __func__); 1187 TCPSTAT_INC(tcps_badsyn); 1188 goto dropunlock; 1189 } 1190 /* 1191 * (SYN|ACK) is bogus on a listen socket. 1192 */ 1193 if (thflags & TH_ACK) { 1194 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1195 log(LOG_DEBUG, "%s; %s: Listen socket: " 1196 "SYN|ACK invalid, segment rejected\n", 1197 s, __func__); 1198 syncache_badack(&inc, port); /* XXX: Not needed! */ 1199 TCPSTAT_INC(tcps_badsyn); 1200 rstreason = BANDLIM_RST_OPENPORT; 1201 goto dropwithreset; 1202 } 1203 /* 1204 * If the drop_synfin option is enabled, drop all 1205 * segments with both the SYN and FIN bits set. 1206 * This prevents e.g. nmap from identifying the 1207 * TCP/IP stack. 1208 * XXX: Poor reasoning. nmap has other methods 1209 * and is constantly refining its stack detection 1210 * strategies. 1211 * XXX: This is a violation of the TCP specification 1212 * and was used by RFC1644. 1213 */ 1214 if ((thflags & TH_FIN) && V_drop_synfin) { 1215 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1216 log(LOG_DEBUG, "%s; %s: Listen socket: " 1217 "SYN|FIN segment ignored (based on " 1218 "sysctl setting)\n", s, __func__); 1219 TCPSTAT_INC(tcps_badsyn); 1220 goto dropunlock; 1221 } 1222 /* 1223 * Segment's flags are (SYN) or (SYN|FIN). 1224 * 1225 * TH_PUSH, TH_URG, TH_ECE, TH_CWR are ignored 1226 * as they do not affect the state of the TCP FSM. 1227 * The data pointed to by TH_URG and th_urp is ignored. 1228 */ 1229 KASSERT((thflags & (TH_RST|TH_ACK)) == 0, 1230 ("%s: Listen socket: TH_RST or TH_ACK set", __func__)); 1231 KASSERT(thflags & (TH_SYN), 1232 ("%s: Listen socket: TH_SYN not set", __func__)); 1233 INP_RLOCK_ASSERT(inp); 1234 #ifdef INET6 1235 /* 1236 * If deprecated address is forbidden, 1237 * we do not accept SYN to deprecated interface 1238 * address to prevent any new inbound connection from 1239 * getting established. 1240 * When we do not accept SYN, we send a TCP RST, 1241 * with deprecated source address (instead of dropping 1242 * it). We compromise it as it is much better for peer 1243 * to send a RST, and RST will be the final packet 1244 * for the exchange. 1245 * 1246 * If we do not forbid deprecated addresses, we accept 1247 * the SYN packet. RFC2462 does not suggest dropping 1248 * SYN in this case. 1249 * If we decipher RFC2462 5.5.4, it says like this: 1250 * 1. use of deprecated addr with existing 1251 * communication is okay - "SHOULD continue to be 1252 * used" 1253 * 2. use of it with new communication: 1254 * (2a) "SHOULD NOT be used if alternate address 1255 * with sufficient scope is available" 1256 * (2b) nothing mentioned otherwise. 1257 * Here we fall into (2b) case as we have no choice in 1258 * our source address selection - we must obey the peer. 1259 * 1260 * The wording in RFC2462 is confusing, and there are 1261 * multiple description text for deprecated address 1262 * handling - worse, they are not exactly the same. 1263 * I believe 5.5.4 is the best one, so we follow 5.5.4. 1264 */ 1265 if (isipv6 && !V_ip6_use_deprecated) { 1266 struct in6_ifaddr *ia6; 1267 1268 ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */, false); 1269 if (ia6 != NULL && 1270 (ia6->ia6_flags & IN6_IFF_DEPRECATED)) { 1271 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1272 log(LOG_DEBUG, "%s; %s: Listen socket: " 1273 "Connection attempt to deprecated " 1274 "IPv6 address rejected\n", 1275 s, __func__); 1276 rstreason = BANDLIM_RST_OPENPORT; 1277 goto dropwithreset; 1278 } 1279 } 1280 #endif /* INET6 */ 1281 /* 1282 * Basic sanity checks on incoming SYN requests: 1283 * Don't respond if the destination is a link layer 1284 * broadcast according to RFC1122 4.2.3.10, p. 104. 1285 * If it is from this socket it must be forged. 1286 * Don't respond if the source or destination is a 1287 * global or subnet broad- or multicast address. 1288 * Note that it is quite possible to receive unicast 1289 * link-layer packets with a broadcast IP address. Use 1290 * in_broadcast() to find them. 1291 */ 1292 if (m->m_flags & (M_BCAST|M_MCAST)) { 1293 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1294 log(LOG_DEBUG, "%s; %s: Listen socket: " 1295 "Connection attempt from broad- or multicast " 1296 "link layer address ignored\n", s, __func__); 1297 goto dropunlock; 1298 } 1299 #ifdef INET6 1300 if (isipv6) { 1301 if (th->th_dport == th->th_sport && 1302 IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &ip6->ip6_src)) { 1303 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1304 log(LOG_DEBUG, "%s; %s: Listen socket: " 1305 "Connection attempt to/from self " 1306 "ignored\n", s, __func__); 1307 goto dropunlock; 1308 } 1309 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 1310 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) { 1311 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1312 log(LOG_DEBUG, "%s; %s: Listen socket: " 1313 "Connection attempt from/to multicast " 1314 "address ignored\n", s, __func__); 1315 goto dropunlock; 1316 } 1317 } 1318 #endif 1319 #if defined(INET) && defined(INET6) 1320 else 1321 #endif 1322 #ifdef INET 1323 { 1324 if (th->th_dport == th->th_sport && 1325 ip->ip_dst.s_addr == ip->ip_src.s_addr) { 1326 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1327 log(LOG_DEBUG, "%s; %s: Listen socket: " 1328 "Connection attempt from/to self " 1329 "ignored\n", s, __func__); 1330 goto dropunlock; 1331 } 1332 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || 1333 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 1334 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || 1335 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) { 1336 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1337 log(LOG_DEBUG, "%s; %s: Listen socket: " 1338 "Connection attempt from/to broad- " 1339 "or multicast address ignored\n", 1340 s, __func__); 1341 goto dropunlock; 1342 } 1343 } 1344 #endif 1345 /* 1346 * SYN appears to be valid. Create compressed TCP state 1347 * for syncache. 1348 */ 1349 #ifdef TCPDEBUG 1350 if (so->so_options & SO_DEBUG) 1351 tcp_trace(TA_INPUT, ostate, tp, 1352 (void *)tcp_saveipgen, &tcp_savetcp, 0); 1353 #endif 1354 TCP_PROBE3(debug__input, tp, th, m); 1355 tcp_dooptions(&to, optp, optlen, TO_SYN); 1356 if ((so = syncache_add(&inc, &to, th, inp, so, m, NULL, NULL, 1357 iptos, port)) != NULL) 1358 goto tfo_socket_result; 1359 1360 /* 1361 * Entry added to syncache and mbuf consumed. 1362 * Only the listen socket is unlocked by syncache_add(). 1363 */ 1364 INP_INFO_WUNLOCK_ASSERT(&V_tcbinfo); 1365 return (IPPROTO_DONE); 1366 } else if (tp->t_state == TCPS_LISTEN) { 1367 /* 1368 * When a listen socket is torn down the SO_ACCEPTCONN 1369 * flag is removed first while connections are drained 1370 * from the accept queue in a unlock/lock cycle of the 1371 * ACCEPT_LOCK, opening a race condition allowing a SYN 1372 * attempt go through unhandled. 1373 */ 1374 goto dropunlock; 1375 } 1376 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 1377 if (tp->t_flags & TF_SIGNATURE) { 1378 tcp_dooptions(&to, optp, optlen, thflags); 1379 if ((to.to_flags & TOF_SIGNATURE) == 0) { 1380 TCPSTAT_INC(tcps_sig_err_nosigopt); 1381 goto dropunlock; 1382 } 1383 if (!TCPMD5_ENABLED() || 1384 TCPMD5_INPUT(m, th, to.to_signature) != 0) 1385 goto dropunlock; 1386 } 1387 #endif 1388 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1389 1390 /* 1391 * Segment belongs to a connection in SYN_SENT, ESTABLISHED or later 1392 * state. tcp_do_segment() always consumes the mbuf chain, unlocks 1393 * the inpcb, and unlocks pcbinfo. 1394 */ 1395 tp->t_fb->tfb_tcp_do_segment(m, th, so, tp, drop_hdrlen, tlen, iptos); 1396 return (IPPROTO_DONE); 1397 1398 dropwithreset: 1399 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1400 1401 if (inp != NULL) { 1402 tcp_dropwithreset(m, th, tp, tlen, rstreason); 1403 INP_UNLOCK(inp); 1404 } else 1405 tcp_dropwithreset(m, th, NULL, tlen, rstreason); 1406 m = NULL; /* mbuf chain got consumed. */ 1407 goto drop; 1408 1409 dropunlock: 1410 if (m != NULL) 1411 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1412 1413 if (inp != NULL) 1414 INP_UNLOCK(inp); 1415 1416 drop: 1417 INP_INFO_WUNLOCK_ASSERT(&V_tcbinfo); 1418 if (s != NULL) 1419 free(s, M_TCPLOG); 1420 if (m != NULL) 1421 m_freem(m); 1422 return (IPPROTO_DONE); 1423 } 1424 1425 /* 1426 * Automatic sizing of receive socket buffer. Often the send 1427 * buffer size is not optimally adjusted to the actual network 1428 * conditions at hand (delay bandwidth product). Setting the 1429 * buffer size too small limits throughput on links with high 1430 * bandwidth and high delay (eg. trans-continental/oceanic links). 1431 * 1432 * On the receive side the socket buffer memory is only rarely 1433 * used to any significant extent. This allows us to be much 1434 * more aggressive in scaling the receive socket buffer. For 1435 * the case that the buffer space is actually used to a large 1436 * extent and we run out of kernel memory we can simply drop 1437 * the new segments; TCP on the sender will just retransmit it 1438 * later. Setting the buffer size too big may only consume too 1439 * much kernel memory if the application doesn't read() from 1440 * the socket or packet loss or reordering makes use of the 1441 * reassembly queue. 1442 * 1443 * The criteria to step up the receive buffer one notch are: 1444 * 1. Application has not set receive buffer size with 1445 * SO_RCVBUF. Setting SO_RCVBUF clears SB_AUTOSIZE. 1446 * 2. the number of bytes received during 1/2 of an sRTT 1447 * is at least 3/8 of the current socket buffer size. 1448 * 3. receive buffer size has not hit maximal automatic size; 1449 * 1450 * If all of the criteria are met we increaset the socket buffer 1451 * by a 1/2 (bounded by the max). This allows us to keep ahead 1452 * of slow-start but also makes it so our peer never gets limited 1453 * by our rwnd which we then open up causing a burst. 1454 * 1455 * This algorithm does two steps per RTT at most and only if 1456 * we receive a bulk stream w/o packet losses or reorderings. 1457 * Shrinking the buffer during idle times is not necessary as 1458 * it doesn't consume any memory when idle. 1459 * 1460 * TODO: Only step up if the application is actually serving 1461 * the buffer to better manage the socket buffer resources. 1462 */ 1463 int 1464 tcp_autorcvbuf(struct mbuf *m, struct tcphdr *th, struct socket *so, 1465 struct tcpcb *tp, int tlen) 1466 { 1467 int newsize = 0; 1468 1469 if (V_tcp_do_autorcvbuf && (so->so_rcv.sb_flags & SB_AUTOSIZE) && 1470 tp->t_srtt != 0 && tp->rfbuf_ts != 0 && 1471 TCP_TS_TO_TICKS(tcp_ts_getticks() - tp->rfbuf_ts) > 1472 ((tp->t_srtt >> TCP_RTT_SHIFT)/2)) { 1473 if (tp->rfbuf_cnt > ((so->so_rcv.sb_hiwat / 2)/ 4 * 3) && 1474 so->so_rcv.sb_hiwat < V_tcp_autorcvbuf_max) { 1475 newsize = min((so->so_rcv.sb_hiwat + (so->so_rcv.sb_hiwat/2)), V_tcp_autorcvbuf_max); 1476 } 1477 TCP_PROBE6(receive__autoresize, NULL, tp, m, tp, th, newsize); 1478 1479 /* Start over with next RTT. */ 1480 tp->rfbuf_ts = 0; 1481 tp->rfbuf_cnt = 0; 1482 } else { 1483 tp->rfbuf_cnt += tlen; /* add up */ 1484 } 1485 return (newsize); 1486 } 1487 1488 int 1489 tcp_input(struct mbuf **mp, int *offp, int proto) 1490 { 1491 return(tcp_input_with_port(mp, offp, proto, 0)); 1492 } 1493 1494 void 1495 tcp_handle_wakeup(struct tcpcb *tp, struct socket *so) 1496 { 1497 /* 1498 * Since tp might be gone if the session entered 1499 * the TIME_WAIT state before coming here, we need 1500 * to check if the socket is still connected. 1501 */ 1502 if ((so->so_state & SS_ISCONNECTED) == 0) 1503 return; 1504 INP_LOCK_ASSERT(tp->t_inpcb); 1505 if (tp->t_flags & TF_WAKESOR) { 1506 tp->t_flags &= ~TF_WAKESOR; 1507 SOCKBUF_UNLOCK_ASSERT(&so->so_rcv); 1508 sorwakeup(so); 1509 } 1510 if (tp->t_flags & TF_WAKESOW) { 1511 tp->t_flags &= ~TF_WAKESOW; 1512 SOCKBUF_UNLOCK_ASSERT(&so->so_snd); 1513 sowwakeup(so); 1514 } 1515 } 1516 1517 void 1518 tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so, 1519 struct tcpcb *tp, int drop_hdrlen, int tlen, uint8_t iptos) 1520 { 1521 int thflags, acked, ourfinisacked, needoutput = 0, sack_changed; 1522 int rstreason, todrop, win, incforsyn = 0; 1523 uint32_t tiwin; 1524 uint16_t nsegs; 1525 char *s; 1526 struct in_conninfo *inc; 1527 struct mbuf *mfree; 1528 struct tcpopt to; 1529 int tfo_syn; 1530 u_int maxseg; 1531 1532 #ifdef TCPDEBUG 1533 /* 1534 * The size of tcp_saveipgen must be the size of the max ip header, 1535 * now IPv6. 1536 */ 1537 u_char tcp_saveipgen[IP6_HDR_LEN]; 1538 struct tcphdr tcp_savetcp; 1539 short ostate = 0; 1540 #endif 1541 thflags = th->th_flags; 1542 inc = &tp->t_inpcb->inp_inc; 1543 tp->sackhint.last_sack_ack = 0; 1544 sack_changed = 0; 1545 nsegs = max(1, m->m_pkthdr.lro_nsegs); 1546 1547 NET_EPOCH_ASSERT(); 1548 INP_WLOCK_ASSERT(tp->t_inpcb); 1549 KASSERT(tp->t_state > TCPS_LISTEN, ("%s: TCPS_LISTEN", 1550 __func__)); 1551 KASSERT(tp->t_state != TCPS_TIME_WAIT, ("%s: TCPS_TIME_WAIT", 1552 __func__)); 1553 1554 #ifdef TCPPCAP 1555 /* Save segment, if requested. */ 1556 tcp_pcap_add(th, m, &(tp->t_inpkts)); 1557 #endif 1558 TCP_LOG_EVENT(tp, th, &so->so_rcv, &so->so_snd, TCP_LOG_IN, 0, 1559 tlen, NULL, true); 1560 1561 if ((thflags & TH_SYN) && (thflags & TH_FIN) && V_drop_synfin) { 1562 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1563 log(LOG_DEBUG, "%s; %s: " 1564 "SYN|FIN segment ignored (based on " 1565 "sysctl setting)\n", s, __func__); 1566 free(s, M_TCPLOG); 1567 } 1568 goto drop; 1569 } 1570 1571 /* 1572 * If a segment with the ACK-bit set arrives in the SYN-SENT state 1573 * check SEQ.ACK first. 1574 */ 1575 if ((tp->t_state == TCPS_SYN_SENT) && (thflags & TH_ACK) && 1576 (SEQ_LEQ(th->th_ack, tp->iss) || SEQ_GT(th->th_ack, tp->snd_max))) { 1577 rstreason = BANDLIM_UNLIMITED; 1578 goto dropwithreset; 1579 } 1580 1581 /* 1582 * Segment received on connection. 1583 * Reset idle time and keep-alive timer. 1584 * XXX: This should be done after segment 1585 * validation to ignore broken/spoofed segs. 1586 */ 1587 tp->t_rcvtime = ticks; 1588 1589 /* 1590 * Scale up the window into a 32-bit value. 1591 * For the SYN_SENT state the scale is zero. 1592 */ 1593 tiwin = th->th_win << tp->snd_scale; 1594 #ifdef STATS 1595 stats_voi_update_abs_ulong(tp->t_stats, VOI_TCP_FRWIN, tiwin); 1596 #endif 1597 1598 /* 1599 * TCP ECN processing. 1600 */ 1601 if (tp->t_flags2 & TF2_ECN_PERMIT) { 1602 if (thflags & TH_CWR) { 1603 tp->t_flags2 &= ~TF2_ECN_SND_ECE; 1604 tp->t_flags |= TF_ACKNOW; 1605 } 1606 switch (iptos & IPTOS_ECN_MASK) { 1607 case IPTOS_ECN_CE: 1608 tp->t_flags2 |= TF2_ECN_SND_ECE; 1609 TCPSTAT_INC(tcps_ecn_ce); 1610 break; 1611 case IPTOS_ECN_ECT0: 1612 TCPSTAT_INC(tcps_ecn_ect0); 1613 break; 1614 case IPTOS_ECN_ECT1: 1615 TCPSTAT_INC(tcps_ecn_ect1); 1616 break; 1617 } 1618 1619 /* Process a packet differently from RFC3168. */ 1620 cc_ecnpkt_handler(tp, th, iptos); 1621 1622 /* Congestion experienced. */ 1623 if (thflags & TH_ECE) { 1624 cc_cong_signal(tp, th, CC_ECN); 1625 } 1626 } 1627 1628 /* 1629 * Parse options on any incoming segment. 1630 */ 1631 tcp_dooptions(&to, (u_char *)(th + 1), 1632 (th->th_off << 2) - sizeof(struct tcphdr), 1633 (thflags & TH_SYN) ? TO_SYN : 0); 1634 1635 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 1636 if ((tp->t_flags & TF_SIGNATURE) != 0 && 1637 (to.to_flags & TOF_SIGNATURE) == 0) { 1638 TCPSTAT_INC(tcps_sig_err_sigopt); 1639 /* XXX: should drop? */ 1640 } 1641 #endif 1642 /* 1643 * If echoed timestamp is later than the current time, 1644 * fall back to non RFC1323 RTT calculation. Normalize 1645 * timestamp if syncookies were used when this connection 1646 * was established. 1647 */ 1648 if ((to.to_flags & TOF_TS) && (to.to_tsecr != 0)) { 1649 to.to_tsecr -= tp->ts_offset; 1650 if (TSTMP_GT(to.to_tsecr, tcp_ts_getticks())) 1651 to.to_tsecr = 0; 1652 else if (tp->t_flags & TF_PREVVALID && 1653 tp->t_badrxtwin != 0 && SEQ_LT(to.to_tsecr, tp->t_badrxtwin)) 1654 cc_cong_signal(tp, th, CC_RTO_ERR); 1655 } 1656 /* 1657 * Process options only when we get SYN/ACK back. The SYN case 1658 * for incoming connections is handled in tcp_syncache. 1659 * According to RFC1323 the window field in a SYN (i.e., a <SYN> 1660 * or <SYN,ACK>) segment itself is never scaled. 1661 * XXX this is traditional behavior, may need to be cleaned up. 1662 */ 1663 if (tp->t_state == TCPS_SYN_SENT && (thflags & TH_SYN)) { 1664 /* Handle parallel SYN for ECN */ 1665 if (!(thflags & TH_ACK) && 1666 ((thflags & (TH_CWR | TH_ECE)) == (TH_CWR | TH_ECE)) && 1667 ((V_tcp_do_ecn == 1) || (V_tcp_do_ecn == 2))) { 1668 tp->t_flags2 |= TF2_ECN_PERMIT; 1669 tp->t_flags2 |= TF2_ECN_SND_ECE; 1670 TCPSTAT_INC(tcps_ecn_shs); 1671 } 1672 if ((to.to_flags & TOF_SCALE) && 1673 (tp->t_flags & TF_REQ_SCALE) && 1674 !(tp->t_flags & TF_NOOPT)) { 1675 tp->t_flags |= TF_RCVD_SCALE; 1676 tp->snd_scale = to.to_wscale; 1677 } else 1678 tp->t_flags &= ~TF_REQ_SCALE; 1679 /* 1680 * Initial send window. It will be updated with 1681 * the next incoming segment to the scaled value. 1682 */ 1683 tp->snd_wnd = th->th_win; 1684 if ((to.to_flags & TOF_TS) && 1685 (tp->t_flags & TF_REQ_TSTMP) && 1686 !(tp->t_flags & TF_NOOPT)) { 1687 tp->t_flags |= TF_RCVD_TSTMP; 1688 tp->ts_recent = to.to_tsval; 1689 tp->ts_recent_age = tcp_ts_getticks(); 1690 } else 1691 tp->t_flags &= ~TF_REQ_TSTMP; 1692 if (to.to_flags & TOF_MSS) 1693 tcp_mss(tp, to.to_mss); 1694 if ((tp->t_flags & TF_SACK_PERMIT) && 1695 (!(to.to_flags & TOF_SACKPERM) || 1696 (tp->t_flags & TF_NOOPT))) 1697 tp->t_flags &= ~TF_SACK_PERMIT; 1698 if (IS_FASTOPEN(tp->t_flags)) { 1699 if ((to.to_flags & TOF_FASTOPEN) && 1700 !(tp->t_flags & TF_NOOPT)) { 1701 uint16_t mss; 1702 1703 if (to.to_flags & TOF_MSS) 1704 mss = to.to_mss; 1705 else 1706 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) 1707 mss = TCP6_MSS; 1708 else 1709 mss = TCP_MSS; 1710 tcp_fastopen_update_cache(tp, mss, 1711 to.to_tfo_len, to.to_tfo_cookie); 1712 } else 1713 tcp_fastopen_disable_path(tp); 1714 } 1715 } 1716 1717 /* 1718 * If timestamps were negotiated during SYN/ACK and a 1719 * segment without a timestamp is received, silently drop 1720 * the segment, unless it is a RST segment or missing timestamps are 1721 * tolerated. 1722 * See section 3.2 of RFC 7323. 1723 */ 1724 if ((tp->t_flags & TF_RCVD_TSTMP) && !(to.to_flags & TOF_TS)) { 1725 if (((thflags & TH_RST) != 0) || V_tcp_tolerate_missing_ts) { 1726 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1727 log(LOG_DEBUG, "%s; %s: Timestamp missing, " 1728 "segment processed normally\n", 1729 s, __func__); 1730 free(s, M_TCPLOG); 1731 } 1732 } else { 1733 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1734 log(LOG_DEBUG, "%s; %s: Timestamp missing, " 1735 "segment silently dropped\n", s, __func__); 1736 free(s, M_TCPLOG); 1737 } 1738 goto drop; 1739 } 1740 } 1741 /* 1742 * If timestamps were not negotiated during SYN/ACK and a 1743 * segment with a timestamp is received, ignore the 1744 * timestamp and process the packet normally. 1745 * See section 3.2 of RFC 7323. 1746 */ 1747 if (!(tp->t_flags & TF_RCVD_TSTMP) && (to.to_flags & TOF_TS)) { 1748 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1749 log(LOG_DEBUG, "%s; %s: Timestamp not expected, " 1750 "segment processed normally\n", s, __func__); 1751 free(s, M_TCPLOG); 1752 } 1753 } 1754 1755 /* 1756 * Header prediction: check for the two common cases 1757 * of a uni-directional data xfer. If the packet has 1758 * no control flags, is in-sequence, the window didn't 1759 * change and we're not retransmitting, it's a 1760 * candidate. If the length is zero and the ack moved 1761 * forward, we're the sender side of the xfer. Just 1762 * free the data acked & wake any higher level process 1763 * that was blocked waiting for space. If the length 1764 * is non-zero and the ack didn't move, we're the 1765 * receiver side. If we're getting packets in-order 1766 * (the reassembly queue is empty), add the data to 1767 * the socket buffer and note that we need a delayed ack. 1768 * Make sure that the hidden state-flags are also off. 1769 * Since we check for TCPS_ESTABLISHED first, it can only 1770 * be TH_NEEDSYN. 1771 */ 1772 if (tp->t_state == TCPS_ESTABLISHED && 1773 th->th_seq == tp->rcv_nxt && 1774 (thflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK && 1775 tp->snd_nxt == tp->snd_max && 1776 tiwin && tiwin == tp->snd_wnd && 1777 ((tp->t_flags & (TF_NEEDSYN|TF_NEEDFIN)) == 0) && 1778 SEGQ_EMPTY(tp) && 1779 ((to.to_flags & TOF_TS) == 0 || 1780 TSTMP_GEQ(to.to_tsval, tp->ts_recent)) ) { 1781 /* 1782 * If last ACK falls within this segment's sequence numbers, 1783 * record the timestamp. 1784 * NOTE that the test is modified according to the latest 1785 * proposal of the [email protected] list (Braden 1993/04/26). 1786 */ 1787 if ((to.to_flags & TOF_TS) != 0 && 1788 SEQ_LEQ(th->th_seq, tp->last_ack_sent)) { 1789 tp->ts_recent_age = tcp_ts_getticks(); 1790 tp->ts_recent = to.to_tsval; 1791 } 1792 1793 if (tlen == 0) { 1794 if (SEQ_GT(th->th_ack, tp->snd_una) && 1795 SEQ_LEQ(th->th_ack, tp->snd_max) && 1796 !IN_RECOVERY(tp->t_flags) && 1797 (to.to_flags & TOF_SACK) == 0 && 1798 TAILQ_EMPTY(&tp->snd_holes)) { 1799 /* 1800 * This is a pure ack for outstanding data. 1801 */ 1802 TCPSTAT_INC(tcps_predack); 1803 1804 /* 1805 * "bad retransmit" recovery without timestamps. 1806 */ 1807 if ((to.to_flags & TOF_TS) == 0 && 1808 tp->t_rxtshift == 1 && 1809 tp->t_flags & TF_PREVVALID && 1810 (int)(ticks - tp->t_badrxtwin) < 0) { 1811 cc_cong_signal(tp, th, CC_RTO_ERR); 1812 } 1813 1814 /* 1815 * Recalculate the transmit timer / rtt. 1816 * 1817 * Some boxes send broken timestamp replies 1818 * during the SYN+ACK phase, ignore 1819 * timestamps of 0 or we could calculate a 1820 * huge RTT and blow up the retransmit timer. 1821 */ 1822 if ((to.to_flags & TOF_TS) != 0 && 1823 to.to_tsecr) { 1824 uint32_t t; 1825 1826 t = tcp_ts_getticks() - to.to_tsecr; 1827 if (!tp->t_rttlow || tp->t_rttlow > t) 1828 tp->t_rttlow = t; 1829 tcp_xmit_timer(tp, 1830 TCP_TS_TO_TICKS(t) + 1); 1831 } else if (tp->t_rtttime && 1832 SEQ_GT(th->th_ack, tp->t_rtseq)) { 1833 if (!tp->t_rttlow || 1834 tp->t_rttlow > ticks - tp->t_rtttime) 1835 tp->t_rttlow = ticks - tp->t_rtttime; 1836 tcp_xmit_timer(tp, 1837 ticks - tp->t_rtttime); 1838 } 1839 acked = BYTES_THIS_ACK(tp, th); 1840 1841 #ifdef TCP_HHOOK 1842 /* Run HHOOK_TCP_ESTABLISHED_IN helper hooks. */ 1843 hhook_run_tcp_est_in(tp, th, &to); 1844 #endif 1845 1846 TCPSTAT_ADD(tcps_rcvackpack, nsegs); 1847 TCPSTAT_ADD(tcps_rcvackbyte, acked); 1848 sbdrop(&so->so_snd, acked); 1849 if (SEQ_GT(tp->snd_una, tp->snd_recover) && 1850 SEQ_LEQ(th->th_ack, tp->snd_recover)) 1851 tp->snd_recover = th->th_ack - 1; 1852 1853 /* 1854 * Let the congestion control algorithm update 1855 * congestion control related information. This 1856 * typically means increasing the congestion 1857 * window. 1858 */ 1859 cc_ack_received(tp, th, nsegs, CC_ACK); 1860 1861 tp->snd_una = th->th_ack; 1862 /* 1863 * Pull snd_wl2 up to prevent seq wrap relative 1864 * to th_ack. 1865 */ 1866 tp->snd_wl2 = th->th_ack; 1867 tp->t_dupacks = 0; 1868 m_freem(m); 1869 1870 /* 1871 * If all outstanding data are acked, stop 1872 * retransmit timer, otherwise restart timer 1873 * using current (possibly backed-off) value. 1874 * If process is waiting for space, 1875 * wakeup/selwakeup/signal. If data 1876 * are ready to send, let tcp_output 1877 * decide between more output or persist. 1878 */ 1879 #ifdef TCPDEBUG 1880 if (so->so_options & SO_DEBUG) 1881 tcp_trace(TA_INPUT, ostate, tp, 1882 (void *)tcp_saveipgen, 1883 &tcp_savetcp, 0); 1884 #endif 1885 TCP_PROBE3(debug__input, tp, th, m); 1886 if (tp->snd_una == tp->snd_max) 1887 tcp_timer_activate(tp, TT_REXMT, 0); 1888 else if (!tcp_timer_active(tp, TT_PERSIST)) 1889 tcp_timer_activate(tp, TT_REXMT, 1890 tp->t_rxtcur); 1891 tp->t_flags |= TF_WAKESOW; 1892 if (sbavail(&so->so_snd)) 1893 (void) tp->t_fb->tfb_tcp_output(tp); 1894 goto check_delack; 1895 } 1896 } else if (th->th_ack == tp->snd_una && 1897 tlen <= sbspace(&so->so_rcv)) { 1898 int newsize = 0; /* automatic sockbuf scaling */ 1899 1900 /* 1901 * This is a pure, in-sequence data packet with 1902 * nothing on the reassembly queue and we have enough 1903 * buffer space to take it. 1904 */ 1905 /* Clean receiver SACK report if present */ 1906 if ((tp->t_flags & TF_SACK_PERMIT) && tp->rcv_numsacks) 1907 tcp_clean_sackreport(tp); 1908 TCPSTAT_INC(tcps_preddat); 1909 tp->rcv_nxt += tlen; 1910 if (tlen && 1911 ((tp->t_flags2 & TF2_FBYTES_COMPLETE) == 0) && 1912 (tp->t_fbyte_in == 0)) { 1913 tp->t_fbyte_in = ticks; 1914 if (tp->t_fbyte_in == 0) 1915 tp->t_fbyte_in = 1; 1916 if (tp->t_fbyte_out && tp->t_fbyte_in) 1917 tp->t_flags2 |= TF2_FBYTES_COMPLETE; 1918 } 1919 /* 1920 * Pull snd_wl1 up to prevent seq wrap relative to 1921 * th_seq. 1922 */ 1923 tp->snd_wl1 = th->th_seq; 1924 /* 1925 * Pull rcv_up up to prevent seq wrap relative to 1926 * rcv_nxt. 1927 */ 1928 tp->rcv_up = tp->rcv_nxt; 1929 TCPSTAT_ADD(tcps_rcvpack, nsegs); 1930 TCPSTAT_ADD(tcps_rcvbyte, tlen); 1931 #ifdef TCPDEBUG 1932 if (so->so_options & SO_DEBUG) 1933 tcp_trace(TA_INPUT, ostate, tp, 1934 (void *)tcp_saveipgen, &tcp_savetcp, 0); 1935 #endif 1936 TCP_PROBE3(debug__input, tp, th, m); 1937 1938 newsize = tcp_autorcvbuf(m, th, so, tp, tlen); 1939 1940 /* Add data to socket buffer. */ 1941 SOCKBUF_LOCK(&so->so_rcv); 1942 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 1943 m_freem(m); 1944 } else { 1945 /* 1946 * Set new socket buffer size. 1947 * Give up when limit is reached. 1948 */ 1949 if (newsize) 1950 if (!sbreserve_locked(&so->so_rcv, 1951 newsize, so, NULL)) 1952 so->so_rcv.sb_flags &= ~SB_AUTOSIZE; 1953 m_adj(m, drop_hdrlen); /* delayed header drop */ 1954 sbappendstream_locked(&so->so_rcv, m, 0); 1955 } 1956 SOCKBUF_UNLOCK(&so->so_rcv); 1957 tp->t_flags |= TF_WAKESOR; 1958 if (DELAY_ACK(tp, tlen)) { 1959 tp->t_flags |= TF_DELACK; 1960 } else { 1961 tp->t_flags |= TF_ACKNOW; 1962 tp->t_fb->tfb_tcp_output(tp); 1963 } 1964 goto check_delack; 1965 } 1966 } 1967 1968 /* 1969 * Calculate amount of space in receive window, 1970 * and then do TCP input processing. 1971 * Receive window is amount of space in rcv queue, 1972 * but not less than advertised window. 1973 */ 1974 win = sbspace(&so->so_rcv); 1975 if (win < 0) 1976 win = 0; 1977 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 1978 1979 switch (tp->t_state) { 1980 /* 1981 * If the state is SYN_RECEIVED: 1982 * if seg contains an ACK, but not for our SYN/ACK, send a RST. 1983 */ 1984 case TCPS_SYN_RECEIVED: 1985 if ((thflags & TH_ACK) && 1986 (SEQ_LEQ(th->th_ack, tp->snd_una) || 1987 SEQ_GT(th->th_ack, tp->snd_max))) { 1988 rstreason = BANDLIM_RST_OPENPORT; 1989 goto dropwithreset; 1990 } 1991 if (IS_FASTOPEN(tp->t_flags)) { 1992 /* 1993 * When a TFO connection is in SYN_RECEIVED, the 1994 * only valid packets are the initial SYN, a 1995 * retransmit/copy of the initial SYN (possibly with 1996 * a subset of the original data), a valid ACK, a 1997 * FIN, or a RST. 1998 */ 1999 if ((thflags & (TH_SYN|TH_ACK)) == (TH_SYN|TH_ACK)) { 2000 rstreason = BANDLIM_RST_OPENPORT; 2001 goto dropwithreset; 2002 } else if (thflags & TH_SYN) { 2003 /* non-initial SYN is ignored */ 2004 if ((tcp_timer_active(tp, TT_DELACK) || 2005 tcp_timer_active(tp, TT_REXMT))) 2006 goto drop; 2007 } else if (!(thflags & (TH_ACK|TH_FIN|TH_RST))) { 2008 goto drop; 2009 } 2010 } 2011 break; 2012 2013 /* 2014 * If the state is SYN_SENT: 2015 * if seg contains a RST with valid ACK (SEQ.ACK has already 2016 * been verified), then drop the connection. 2017 * if seg contains a RST without an ACK, drop the seg. 2018 * if seg does not contain SYN, then drop the seg. 2019 * Otherwise this is an acceptable SYN segment 2020 * initialize tp->rcv_nxt and tp->irs 2021 * if seg contains ack then advance tp->snd_una 2022 * if seg contains an ECE and ECN support is enabled, the stream 2023 * is ECN capable. 2024 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 2025 * arrange for segment to be acked (eventually) 2026 * continue processing rest of data/controls, beginning with URG 2027 */ 2028 case TCPS_SYN_SENT: 2029 if ((thflags & (TH_ACK|TH_RST)) == (TH_ACK|TH_RST)) { 2030 TCP_PROBE5(connect__refused, NULL, tp, 2031 m, tp, th); 2032 tp = tcp_drop(tp, ECONNREFUSED); 2033 } 2034 if (thflags & TH_RST) 2035 goto drop; 2036 if (!(thflags & TH_SYN)) 2037 goto drop; 2038 2039 tp->irs = th->th_seq; 2040 tcp_rcvseqinit(tp); 2041 if (thflags & TH_ACK) { 2042 int tfo_partial_ack = 0; 2043 2044 TCPSTAT_INC(tcps_connects); 2045 soisconnected(so); 2046 #ifdef MAC 2047 mac_socketpeer_set_from_mbuf(m, so); 2048 #endif 2049 /* Do window scaling on this connection? */ 2050 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2051 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2052 tp->rcv_scale = tp->request_r_scale; 2053 } 2054 tp->rcv_adv += min(tp->rcv_wnd, 2055 TCP_MAXWIN << tp->rcv_scale); 2056 tp->snd_una++; /* SYN is acked */ 2057 /* 2058 * If not all the data that was sent in the TFO SYN 2059 * has been acked, resend the remainder right away. 2060 */ 2061 if (IS_FASTOPEN(tp->t_flags) && 2062 (tp->snd_una != tp->snd_max)) { 2063 tp->snd_nxt = th->th_ack; 2064 tfo_partial_ack = 1; 2065 } 2066 /* 2067 * If there's data, delay ACK; if there's also a FIN 2068 * ACKNOW will be turned on later. 2069 */ 2070 if (DELAY_ACK(tp, tlen) && tlen != 0 && !tfo_partial_ack) 2071 tcp_timer_activate(tp, TT_DELACK, 2072 tcp_delacktime); 2073 else 2074 tp->t_flags |= TF_ACKNOW; 2075 2076 if (((thflags & (TH_CWR | TH_ECE)) == TH_ECE) && 2077 (V_tcp_do_ecn == 1)) { 2078 tp->t_flags2 |= TF2_ECN_PERMIT; 2079 TCPSTAT_INC(tcps_ecn_shs); 2080 } 2081 2082 /* 2083 * Received <SYN,ACK> in SYN_SENT[*] state. 2084 * Transitions: 2085 * SYN_SENT --> ESTABLISHED 2086 * SYN_SENT* --> FIN_WAIT_1 2087 */ 2088 tp->t_starttime = ticks; 2089 if (tp->t_flags & TF_NEEDFIN) { 2090 tcp_state_change(tp, TCPS_FIN_WAIT_1); 2091 tp->t_flags &= ~TF_NEEDFIN; 2092 thflags &= ~TH_SYN; 2093 } else { 2094 tcp_state_change(tp, TCPS_ESTABLISHED); 2095 TCP_PROBE5(connect__established, NULL, tp, 2096 m, tp, th); 2097 cc_conn_init(tp); 2098 tcp_timer_activate(tp, TT_KEEP, 2099 TP_KEEPIDLE(tp)); 2100 } 2101 } else { 2102 /* 2103 * Received initial SYN in SYN-SENT[*] state => 2104 * simultaneous open. 2105 * If it succeeds, connection is * half-synchronized. 2106 * Otherwise, do 3-way handshake: 2107 * SYN-SENT -> SYN-RECEIVED 2108 * SYN-SENT* -> SYN-RECEIVED* 2109 */ 2110 tp->t_flags |= (TF_ACKNOW | TF_NEEDSYN); 2111 tcp_timer_activate(tp, TT_REXMT, 0); 2112 tcp_state_change(tp, TCPS_SYN_RECEIVED); 2113 } 2114 2115 INP_WLOCK_ASSERT(tp->t_inpcb); 2116 2117 /* 2118 * Advance th->th_seq to correspond to first data byte. 2119 * If data, trim to stay within window, 2120 * dropping FIN if necessary. 2121 */ 2122 th->th_seq++; 2123 if (tlen > tp->rcv_wnd) { 2124 todrop = tlen - tp->rcv_wnd; 2125 m_adj(m, -todrop); 2126 tlen = tp->rcv_wnd; 2127 thflags &= ~TH_FIN; 2128 TCPSTAT_INC(tcps_rcvpackafterwin); 2129 TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); 2130 } 2131 tp->snd_wl1 = th->th_seq - 1; 2132 tp->rcv_up = th->th_seq; 2133 /* 2134 * Client side of transaction: already sent SYN and data. 2135 * If the remote host used T/TCP to validate the SYN, 2136 * our data will be ACK'd; if so, enter normal data segment 2137 * processing in the middle of step 5, ack processing. 2138 * Otherwise, goto step 6. 2139 */ 2140 if (thflags & TH_ACK) 2141 goto process_ACK; 2142 2143 goto step6; 2144 2145 /* 2146 * If the state is LAST_ACK or CLOSING or TIME_WAIT: 2147 * do normal processing. 2148 * 2149 * NB: Leftover from RFC1644 T/TCP. Cases to be reused later. 2150 */ 2151 case TCPS_LAST_ACK: 2152 case TCPS_CLOSING: 2153 break; /* continue normal processing */ 2154 } 2155 2156 /* 2157 * States other than LISTEN or SYN_SENT. 2158 * First check the RST flag and sequence number since reset segments 2159 * are exempt from the timestamp and connection count tests. This 2160 * fixes a bug introduced by the Stevens, vol. 2, p. 960 bugfix 2161 * below which allowed reset segments in half the sequence space 2162 * to fall though and be processed (which gives forged reset 2163 * segments with a random sequence number a 50 percent chance of 2164 * killing a connection). 2165 * Then check timestamp, if present. 2166 * Then check the connection count, if present. 2167 * Then check that at least some bytes of segment are within 2168 * receive window. If segment begins before rcv_nxt, 2169 * drop leading data (and SYN); if nothing left, just ack. 2170 */ 2171 if (thflags & TH_RST) { 2172 /* 2173 * RFC5961 Section 3.2 2174 * 2175 * - RST drops connection only if SEG.SEQ == RCV.NXT. 2176 * - If RST is in window, we send challenge ACK. 2177 * 2178 * Note: to take into account delayed ACKs, we should 2179 * test against last_ack_sent instead of rcv_nxt. 2180 * Note 2: we handle special case of closed window, not 2181 * covered by the RFC. 2182 */ 2183 if ((SEQ_GEQ(th->th_seq, tp->last_ack_sent) && 2184 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) || 2185 (tp->rcv_wnd == 0 && tp->last_ack_sent == th->th_seq)) { 2186 KASSERT(tp->t_state != TCPS_SYN_SENT, 2187 ("%s: TH_RST for TCPS_SYN_SENT th %p tp %p", 2188 __func__, th, tp)); 2189 2190 if (V_tcp_insecure_rst || 2191 tp->last_ack_sent == th->th_seq) { 2192 TCPSTAT_INC(tcps_drops); 2193 /* Drop the connection. */ 2194 switch (tp->t_state) { 2195 case TCPS_SYN_RECEIVED: 2196 so->so_error = ECONNREFUSED; 2197 goto close; 2198 case TCPS_ESTABLISHED: 2199 case TCPS_FIN_WAIT_1: 2200 case TCPS_FIN_WAIT_2: 2201 case TCPS_CLOSE_WAIT: 2202 case TCPS_CLOSING: 2203 case TCPS_LAST_ACK: 2204 so->so_error = ECONNRESET; 2205 close: 2206 /* FALLTHROUGH */ 2207 default: 2208 tp = tcp_close(tp); 2209 } 2210 } else { 2211 TCPSTAT_INC(tcps_badrst); 2212 /* Send challenge ACK. */ 2213 tcp_respond(tp, mtod(m, void *), th, m, 2214 tp->rcv_nxt, tp->snd_nxt, TH_ACK); 2215 tp->last_ack_sent = tp->rcv_nxt; 2216 m = NULL; 2217 } 2218 } 2219 goto drop; 2220 } 2221 2222 /* 2223 * RFC5961 Section 4.2 2224 * Send challenge ACK for any SYN in synchronized state. 2225 */ 2226 if ((thflags & TH_SYN) && tp->t_state != TCPS_SYN_SENT && 2227 tp->t_state != TCPS_SYN_RECEIVED) { 2228 TCPSTAT_INC(tcps_badsyn); 2229 if (V_tcp_insecure_syn && 2230 SEQ_GEQ(th->th_seq, tp->last_ack_sent) && 2231 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) { 2232 tp = tcp_drop(tp, ECONNRESET); 2233 rstreason = BANDLIM_UNLIMITED; 2234 } else { 2235 /* Send challenge ACK. */ 2236 tcp_respond(tp, mtod(m, void *), th, m, tp->rcv_nxt, 2237 tp->snd_nxt, TH_ACK); 2238 tp->last_ack_sent = tp->rcv_nxt; 2239 m = NULL; 2240 } 2241 goto drop; 2242 } 2243 2244 /* 2245 * RFC 1323 PAWS: If we have a timestamp reply on this segment 2246 * and it's less than ts_recent, drop it. 2247 */ 2248 if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent && 2249 TSTMP_LT(to.to_tsval, tp->ts_recent)) { 2250 /* Check to see if ts_recent is over 24 days old. */ 2251 if (tcp_ts_getticks() - tp->ts_recent_age > TCP_PAWS_IDLE) { 2252 /* 2253 * Invalidate ts_recent. If this segment updates 2254 * ts_recent, the age will be reset later and ts_recent 2255 * will get a valid value. If it does not, setting 2256 * ts_recent to zero will at least satisfy the 2257 * requirement that zero be placed in the timestamp 2258 * echo reply when ts_recent isn't valid. The 2259 * age isn't reset until we get a valid ts_recent 2260 * because we don't want out-of-order segments to be 2261 * dropped when ts_recent is old. 2262 */ 2263 tp->ts_recent = 0; 2264 } else { 2265 TCPSTAT_INC(tcps_rcvduppack); 2266 TCPSTAT_ADD(tcps_rcvdupbyte, tlen); 2267 TCPSTAT_INC(tcps_pawsdrop); 2268 if (tlen) 2269 goto dropafterack; 2270 goto drop; 2271 } 2272 } 2273 2274 /* 2275 * In the SYN-RECEIVED state, validate that the packet belongs to 2276 * this connection before trimming the data to fit the receive 2277 * window. Check the sequence number versus IRS since we know 2278 * the sequence numbers haven't wrapped. This is a partial fix 2279 * for the "LAND" DoS attack. 2280 */ 2281 if (tp->t_state == TCPS_SYN_RECEIVED && SEQ_LT(th->th_seq, tp->irs)) { 2282 rstreason = BANDLIM_RST_OPENPORT; 2283 goto dropwithreset; 2284 } 2285 2286 todrop = tp->rcv_nxt - th->th_seq; 2287 if (todrop > 0) { 2288 if (thflags & TH_SYN) { 2289 thflags &= ~TH_SYN; 2290 th->th_seq++; 2291 if (th->th_urp > 1) 2292 th->th_urp--; 2293 else 2294 thflags &= ~TH_URG; 2295 todrop--; 2296 } 2297 /* 2298 * Following if statement from Stevens, vol. 2, p. 960. 2299 */ 2300 if (todrop > tlen 2301 || (todrop == tlen && (thflags & TH_FIN) == 0)) { 2302 /* 2303 * Any valid FIN must be to the left of the window. 2304 * At this point the FIN must be a duplicate or out 2305 * of sequence; drop it. 2306 */ 2307 thflags &= ~TH_FIN; 2308 2309 /* 2310 * Send an ACK to resynchronize and drop any data. 2311 * But keep on processing for RST or ACK. 2312 */ 2313 tp->t_flags |= TF_ACKNOW; 2314 todrop = tlen; 2315 TCPSTAT_INC(tcps_rcvduppack); 2316 TCPSTAT_ADD(tcps_rcvdupbyte, todrop); 2317 } else { 2318 TCPSTAT_INC(tcps_rcvpartduppack); 2319 TCPSTAT_ADD(tcps_rcvpartdupbyte, todrop); 2320 } 2321 /* 2322 * DSACK - add SACK block for dropped range 2323 */ 2324 if ((todrop > 0) && (tp->t_flags & TF_SACK_PERMIT)) { 2325 tcp_update_sack_list(tp, th->th_seq, 2326 th->th_seq + todrop); 2327 /* 2328 * ACK now, as the next in-sequence segment 2329 * will clear the DSACK block again 2330 */ 2331 tp->t_flags |= TF_ACKNOW; 2332 } 2333 drop_hdrlen += todrop; /* drop from the top afterwards */ 2334 th->th_seq += todrop; 2335 tlen -= todrop; 2336 if (th->th_urp > todrop) 2337 th->th_urp -= todrop; 2338 else { 2339 thflags &= ~TH_URG; 2340 th->th_urp = 0; 2341 } 2342 } 2343 2344 /* 2345 * If new data are received on a connection after the 2346 * user processes are gone, then RST the other end. 2347 */ 2348 if ((so->so_state & SS_NOFDREF) && 2349 tp->t_state > TCPS_CLOSE_WAIT && tlen) { 2350 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 2351 log(LOG_DEBUG, "%s; %s: %s: Received %d bytes of data " 2352 "after socket was closed, " 2353 "sending RST and removing tcpcb\n", 2354 s, __func__, tcpstates[tp->t_state], tlen); 2355 free(s, M_TCPLOG); 2356 } 2357 tp = tcp_close(tp); 2358 TCPSTAT_INC(tcps_rcvafterclose); 2359 rstreason = BANDLIM_UNLIMITED; 2360 goto dropwithreset; 2361 } 2362 2363 /* 2364 * If segment ends after window, drop trailing data 2365 * (and PUSH and FIN); if nothing left, just ACK. 2366 */ 2367 todrop = (th->th_seq + tlen) - (tp->rcv_nxt + tp->rcv_wnd); 2368 if (todrop > 0) { 2369 TCPSTAT_INC(tcps_rcvpackafterwin); 2370 if (todrop >= tlen) { 2371 TCPSTAT_ADD(tcps_rcvbyteafterwin, tlen); 2372 /* 2373 * If window is closed can only take segments at 2374 * window edge, and have to drop data and PUSH from 2375 * incoming segments. Continue processing, but 2376 * remember to ack. Otherwise, drop segment 2377 * and ack. 2378 */ 2379 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 2380 tp->t_flags |= TF_ACKNOW; 2381 TCPSTAT_INC(tcps_rcvwinprobe); 2382 } else 2383 goto dropafterack; 2384 } else 2385 TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); 2386 m_adj(m, -todrop); 2387 tlen -= todrop; 2388 thflags &= ~(TH_PUSH|TH_FIN); 2389 } 2390 2391 /* 2392 * If last ACK falls within this segment's sequence numbers, 2393 * record its timestamp. 2394 * NOTE: 2395 * 1) That the test incorporates suggestions from the latest 2396 * proposal of the [email protected] list (Braden 1993/04/26). 2397 * 2) That updating only on newer timestamps interferes with 2398 * our earlier PAWS tests, so this check should be solely 2399 * predicated on the sequence space of this segment. 2400 * 3) That we modify the segment boundary check to be 2401 * Last.ACK.Sent <= SEG.SEQ + SEG.Len 2402 * instead of RFC1323's 2403 * Last.ACK.Sent < SEG.SEQ + SEG.Len, 2404 * This modified check allows us to overcome RFC1323's 2405 * limitations as described in Stevens TCP/IP Illustrated 2406 * Vol. 2 p.869. In such cases, we can still calculate the 2407 * RTT correctly when RCV.NXT == Last.ACK.Sent. 2408 */ 2409 if ((to.to_flags & TOF_TS) != 0 && 2410 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 2411 SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen + 2412 ((thflags & (TH_SYN|TH_FIN)) != 0))) { 2413 tp->ts_recent_age = tcp_ts_getticks(); 2414 tp->ts_recent = to.to_tsval; 2415 } 2416 2417 /* 2418 * If the ACK bit is off: if in SYN-RECEIVED state or SENDSYN 2419 * flag is on (half-synchronized state), then queue data for 2420 * later processing; else drop segment and return. 2421 */ 2422 if ((thflags & TH_ACK) == 0) { 2423 if (tp->t_state == TCPS_SYN_RECEIVED || 2424 (tp->t_flags & TF_NEEDSYN)) { 2425 if (tp->t_state == TCPS_SYN_RECEIVED && 2426 IS_FASTOPEN(tp->t_flags)) { 2427 tp->snd_wnd = tiwin; 2428 cc_conn_init(tp); 2429 } 2430 goto step6; 2431 } else if (tp->t_flags & TF_ACKNOW) 2432 goto dropafterack; 2433 else 2434 goto drop; 2435 } 2436 2437 /* 2438 * Ack processing. 2439 */ 2440 switch (tp->t_state) { 2441 /* 2442 * In SYN_RECEIVED state, the ack ACKs our SYN, so enter 2443 * ESTABLISHED state and continue processing. 2444 * The ACK was checked above. 2445 */ 2446 case TCPS_SYN_RECEIVED: 2447 2448 TCPSTAT_INC(tcps_connects); 2449 soisconnected(so); 2450 /* Do window scaling? */ 2451 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2452 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2453 tp->rcv_scale = tp->request_r_scale; 2454 } 2455 tp->snd_wnd = tiwin; 2456 /* 2457 * Make transitions: 2458 * SYN-RECEIVED -> ESTABLISHED 2459 * SYN-RECEIVED* -> FIN-WAIT-1 2460 */ 2461 tp->t_starttime = ticks; 2462 if (IS_FASTOPEN(tp->t_flags) && tp->t_tfo_pending) { 2463 tcp_fastopen_decrement_counter(tp->t_tfo_pending); 2464 tp->t_tfo_pending = NULL; 2465 } 2466 if (tp->t_flags & TF_NEEDFIN) { 2467 tcp_state_change(tp, TCPS_FIN_WAIT_1); 2468 tp->t_flags &= ~TF_NEEDFIN; 2469 } else { 2470 tcp_state_change(tp, TCPS_ESTABLISHED); 2471 TCP_PROBE5(accept__established, NULL, tp, 2472 m, tp, th); 2473 /* 2474 * TFO connections call cc_conn_init() during SYN 2475 * processing. Calling it again here for such 2476 * connections is not harmless as it would undo the 2477 * snd_cwnd reduction that occurs when a TFO SYN|ACK 2478 * is retransmitted. 2479 */ 2480 if (!IS_FASTOPEN(tp->t_flags)) 2481 cc_conn_init(tp); 2482 tcp_timer_activate(tp, TT_KEEP, TP_KEEPIDLE(tp)); 2483 } 2484 /* 2485 * Account for the ACK of our SYN prior to 2486 * regular ACK processing below, except for 2487 * simultaneous SYN, which is handled later. 2488 */ 2489 if (SEQ_GT(th->th_ack, tp->snd_una) && !(tp->t_flags & TF_NEEDSYN)) 2490 incforsyn = 1; 2491 /* 2492 * If segment contains data or ACK, will call tcp_reass() 2493 * later; if not, do so now to pass queued data to user. 2494 */ 2495 if (tlen == 0 && (thflags & TH_FIN) == 0) 2496 (void) tcp_reass(tp, (struct tcphdr *)0, NULL, 0, 2497 (struct mbuf *)0); 2498 tp->snd_wl1 = th->th_seq - 1; 2499 /* FALLTHROUGH */ 2500 2501 /* 2502 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 2503 * ACKs. If the ack is in the range 2504 * tp->snd_una < th->th_ack <= tp->snd_max 2505 * then advance tp->snd_una to th->th_ack and drop 2506 * data from the retransmission queue. If this ACK reflects 2507 * more up to date window information we update our window information. 2508 */ 2509 case TCPS_ESTABLISHED: 2510 case TCPS_FIN_WAIT_1: 2511 case TCPS_FIN_WAIT_2: 2512 case TCPS_CLOSE_WAIT: 2513 case TCPS_CLOSING: 2514 case TCPS_LAST_ACK: 2515 if (SEQ_GT(th->th_ack, tp->snd_max)) { 2516 TCPSTAT_INC(tcps_rcvacktoomuch); 2517 goto dropafterack; 2518 } 2519 if ((tp->t_flags & TF_SACK_PERMIT) && 2520 ((to.to_flags & TOF_SACK) || 2521 !TAILQ_EMPTY(&tp->snd_holes))) 2522 sack_changed = tcp_sack_doack(tp, &to, th->th_ack); 2523 else 2524 /* 2525 * Reset the value so that previous (valid) value 2526 * from the last ack with SACK doesn't get used. 2527 */ 2528 tp->sackhint.sacked_bytes = 0; 2529 2530 #ifdef TCP_HHOOK 2531 /* Run HHOOK_TCP_ESTABLISHED_IN helper hooks. */ 2532 hhook_run_tcp_est_in(tp, th, &to); 2533 #endif 2534 2535 if (SEQ_LEQ(th->th_ack, tp->snd_una)) { 2536 maxseg = tcp_maxseg(tp); 2537 if (tlen == 0 && 2538 (tiwin == tp->snd_wnd || 2539 (tp->t_flags & TF_SACK_PERMIT))) { 2540 /* 2541 * If this is the first time we've seen a 2542 * FIN from the remote, this is not a 2543 * duplicate and it needs to be processed 2544 * normally. This happens during a 2545 * simultaneous close. 2546 */ 2547 if ((thflags & TH_FIN) && 2548 (TCPS_HAVERCVDFIN(tp->t_state) == 0)) { 2549 tp->t_dupacks = 0; 2550 break; 2551 } 2552 TCPSTAT_INC(tcps_rcvdupack); 2553 /* 2554 * If we have outstanding data (other than 2555 * a window probe), this is a completely 2556 * duplicate ack (ie, window info didn't 2557 * change and FIN isn't set), 2558 * the ack is the biggest we've 2559 * seen and we've seen exactly our rexmt 2560 * threshold of them, assume a packet 2561 * has been dropped and retransmit it. 2562 * Kludge snd_nxt & the congestion 2563 * window so we send only this one 2564 * packet. 2565 * 2566 * We know we're losing at the current 2567 * window size so do congestion avoidance 2568 * (set ssthresh to half the current window 2569 * and pull our congestion window back to 2570 * the new ssthresh). 2571 * 2572 * Dup acks mean that packets have left the 2573 * network (they're now cached at the receiver) 2574 * so bump cwnd by the amount in the receiver 2575 * to keep a constant cwnd packets in the 2576 * network. 2577 * 2578 * When using TCP ECN, notify the peer that 2579 * we reduced the cwnd. 2580 */ 2581 /* 2582 * Following 2 kinds of acks should not affect 2583 * dupack counting: 2584 * 1) Old acks 2585 * 2) Acks with SACK but without any new SACK 2586 * information in them. These could result from 2587 * any anomaly in the network like a switch 2588 * duplicating packets or a possible DoS attack. 2589 */ 2590 if (th->th_ack != tp->snd_una || 2591 ((tp->t_flags & TF_SACK_PERMIT) && 2592 (to.to_flags & TOF_SACK) && 2593 !sack_changed)) 2594 break; 2595 else if (!tcp_timer_active(tp, TT_REXMT)) 2596 tp->t_dupacks = 0; 2597 else if (++tp->t_dupacks > tcprexmtthresh || 2598 IN_FASTRECOVERY(tp->t_flags)) { 2599 cc_ack_received(tp, th, nsegs, 2600 CC_DUPACK); 2601 if (V_tcp_do_prr && 2602 IN_FASTRECOVERY(tp->t_flags) && 2603 (tp->t_flags & TF_SACK_PERMIT)) { 2604 tcp_do_prr_ack(tp, th, &to); 2605 } else if ((tp->t_flags & TF_SACK_PERMIT) && 2606 (to.to_flags & TOF_SACK) && 2607 IN_FASTRECOVERY(tp->t_flags)) { 2608 int awnd; 2609 2610 /* 2611 * Compute the amount of data in flight first. 2612 * We can inject new data into the pipe iff 2613 * we have less than 1/2 the original window's 2614 * worth of data in flight. 2615 */ 2616 if (V_tcp_do_newsack) 2617 awnd = tcp_compute_pipe(tp); 2618 else 2619 awnd = (tp->snd_nxt - tp->snd_fack) + 2620 tp->sackhint.sack_bytes_rexmit; 2621 2622 if (awnd < tp->snd_ssthresh) { 2623 tp->snd_cwnd += maxseg; 2624 if (tp->snd_cwnd > tp->snd_ssthresh) 2625 tp->snd_cwnd = tp->snd_ssthresh; 2626 } 2627 } else 2628 tp->snd_cwnd += maxseg; 2629 (void) tp->t_fb->tfb_tcp_output(tp); 2630 goto drop; 2631 } else if (tp->t_dupacks == tcprexmtthresh || 2632 (tp->t_flags & TF_SACK_PERMIT && 2633 V_tcp_do_newsack && 2634 tp->sackhint.sacked_bytes > 2635 (tcprexmtthresh - 1) * maxseg)) { 2636 enter_recovery: 2637 /* 2638 * Above is the RFC6675 trigger condition of 2639 * more than (dupthresh-1)*maxseg sacked data. 2640 * If the count of holes in the 2641 * scoreboard is >= dupthresh, we could 2642 * also enter loss recovery, but don't 2643 * have that value readily available. 2644 */ 2645 tp->t_dupacks = tcprexmtthresh; 2646 tcp_seq onxt = tp->snd_nxt; 2647 2648 /* 2649 * If we're doing sack, or prr, check 2650 * to see if we're already in sack 2651 * recovery. If we're not doing sack, 2652 * check to see if we're in newreno 2653 * recovery. 2654 */ 2655 if (V_tcp_do_prr || 2656 (tp->t_flags & TF_SACK_PERMIT)) { 2657 if (IN_FASTRECOVERY(tp->t_flags)) { 2658 tp->t_dupacks = 0; 2659 break; 2660 } 2661 } else { 2662 if (SEQ_LEQ(th->th_ack, 2663 tp->snd_recover)) { 2664 tp->t_dupacks = 0; 2665 break; 2666 } 2667 } 2668 /* Congestion signal before ack. */ 2669 cc_cong_signal(tp, th, CC_NDUPACK); 2670 cc_ack_received(tp, th, nsegs, 2671 CC_DUPACK); 2672 tcp_timer_activate(tp, TT_REXMT, 0); 2673 tp->t_rtttime = 0; 2674 if (V_tcp_do_prr) { 2675 /* 2676 * snd_ssthresh is already updated by 2677 * cc_cong_signal. 2678 */ 2679 tp->sackhint.prr_delivered = 2680 tp->sackhint.sacked_bytes; 2681 tp->sackhint.recover_fs = max(1, 2682 tp->snd_nxt - tp->snd_una); 2683 } 2684 if ((tp->t_flags & TF_SACK_PERMIT) && 2685 (to.to_flags & TOF_SACK)) { 2686 TCPSTAT_INC( 2687 tcps_sack_recovery_episode); 2688 tp->snd_recover = tp->snd_nxt; 2689 tp->snd_cwnd = maxseg; 2690 (void) tp->t_fb->tfb_tcp_output(tp); 2691 if (SEQ_GT(th->th_ack, tp->snd_una)) 2692 goto resume_partialack; 2693 goto drop; 2694 } 2695 tp->snd_nxt = th->th_ack; 2696 tp->snd_cwnd = maxseg; 2697 (void) tp->t_fb->tfb_tcp_output(tp); 2698 KASSERT(tp->snd_limited <= 2, 2699 ("%s: tp->snd_limited too big", 2700 __func__)); 2701 tp->snd_cwnd = tp->snd_ssthresh + 2702 maxseg * 2703 (tp->t_dupacks - tp->snd_limited); 2704 if (SEQ_GT(onxt, tp->snd_nxt)) 2705 tp->snd_nxt = onxt; 2706 goto drop; 2707 } else if (V_tcp_do_rfc3042) { 2708 /* 2709 * Process first and second duplicate 2710 * ACKs. Each indicates a segment 2711 * leaving the network, creating room 2712 * for more. Make sure we can send a 2713 * packet on reception of each duplicate 2714 * ACK by increasing snd_cwnd by one 2715 * segment. Restore the original 2716 * snd_cwnd after packet transmission. 2717 */ 2718 cc_ack_received(tp, th, nsegs, 2719 CC_DUPACK); 2720 uint32_t oldcwnd = tp->snd_cwnd; 2721 tcp_seq oldsndmax = tp->snd_max; 2722 u_int sent; 2723 int avail; 2724 2725 KASSERT(tp->t_dupacks == 1 || 2726 tp->t_dupacks == 2, 2727 ("%s: dupacks not 1 or 2", 2728 __func__)); 2729 if (tp->t_dupacks == 1) 2730 tp->snd_limited = 0; 2731 tp->snd_cwnd = 2732 (tp->snd_nxt - tp->snd_una) + 2733 (tp->t_dupacks - tp->snd_limited) * 2734 maxseg; 2735 /* 2736 * Only call tcp_output when there 2737 * is new data available to be sent. 2738 * Otherwise we would send pure ACKs. 2739 */ 2740 SOCKBUF_LOCK(&so->so_snd); 2741 avail = sbavail(&so->so_snd) - 2742 (tp->snd_nxt - tp->snd_una); 2743 SOCKBUF_UNLOCK(&so->so_snd); 2744 if (avail > 0) 2745 (void) tp->t_fb->tfb_tcp_output(tp); 2746 sent = tp->snd_max - oldsndmax; 2747 if (sent > maxseg) { 2748 KASSERT((tp->t_dupacks == 2 && 2749 tp->snd_limited == 0) || 2750 (sent == maxseg + 1 && 2751 tp->t_flags & TF_SENTFIN), 2752 ("%s: sent too much", 2753 __func__)); 2754 tp->snd_limited = 2; 2755 } else if (sent > 0) 2756 ++tp->snd_limited; 2757 tp->snd_cwnd = oldcwnd; 2758 goto drop; 2759 } 2760 } 2761 break; 2762 } else { 2763 /* 2764 * This ack is advancing the left edge, reset the 2765 * counter. 2766 */ 2767 tp->t_dupacks = 0; 2768 /* 2769 * If this ack also has new SACK info, increment the 2770 * counter as per rfc6675. The variable 2771 * sack_changed tracks all changes to the SACK 2772 * scoreboard, including when partial ACKs without 2773 * SACK options are received, and clear the scoreboard 2774 * from the left side. Such partial ACKs should not be 2775 * counted as dupacks here. 2776 */ 2777 if ((tp->t_flags & TF_SACK_PERMIT) && 2778 (to.to_flags & TOF_SACK) && 2779 sack_changed) { 2780 tp->t_dupacks++; 2781 /* limit overhead by setting maxseg last */ 2782 if (!IN_FASTRECOVERY(tp->t_flags) && 2783 (tp->sackhint.sacked_bytes > 2784 ((tcprexmtthresh - 1) * 2785 (maxseg = tcp_maxseg(tp))))) { 2786 goto enter_recovery; 2787 } 2788 } 2789 } 2790 2791 resume_partialack: 2792 KASSERT(SEQ_GT(th->th_ack, tp->snd_una), 2793 ("%s: th_ack <= snd_una", __func__)); 2794 2795 /* 2796 * If the congestion window was inflated to account 2797 * for the other side's cached packets, retract it. 2798 */ 2799 if (IN_FASTRECOVERY(tp->t_flags)) { 2800 if (SEQ_LT(th->th_ack, tp->snd_recover)) { 2801 if (tp->t_flags & TF_SACK_PERMIT) 2802 if (V_tcp_do_prr && to.to_flags & TOF_SACK) { 2803 tcp_timer_activate(tp, TT_REXMT, 0); 2804 tp->t_rtttime = 0; 2805 tcp_do_prr_ack(tp, th, &to); 2806 tp->t_flags |= TF_ACKNOW; 2807 (void) tcp_output(tp); 2808 } else 2809 tcp_sack_partialack(tp, th); 2810 else 2811 tcp_newreno_partial_ack(tp, th); 2812 } else 2813 cc_post_recovery(tp, th); 2814 } else if (IN_CONGRECOVERY(tp->t_flags)) { 2815 if (SEQ_LT(th->th_ack, tp->snd_recover)) { 2816 if (V_tcp_do_prr) { 2817 tp->sackhint.delivered_data = BYTES_THIS_ACK(tp, th); 2818 tp->snd_fack = th->th_ack; 2819 tcp_do_prr_ack(tp, th, &to); 2820 (void) tcp_output(tp); 2821 } 2822 } else 2823 cc_post_recovery(tp, th); 2824 } 2825 /* 2826 * If we reach this point, ACK is not a duplicate, 2827 * i.e., it ACKs something we sent. 2828 */ 2829 if (tp->t_flags & TF_NEEDSYN) { 2830 /* 2831 * T/TCP: Connection was half-synchronized, and our 2832 * SYN has been ACK'd (so connection is now fully 2833 * synchronized). Go to non-starred state, 2834 * increment snd_una for ACK of SYN, and check if 2835 * we can do window scaling. 2836 */ 2837 tp->t_flags &= ~TF_NEEDSYN; 2838 tp->snd_una++; 2839 /* Do window scaling? */ 2840 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2841 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2842 tp->rcv_scale = tp->request_r_scale; 2843 /* Send window already scaled. */ 2844 } 2845 } 2846 2847 process_ACK: 2848 INP_WLOCK_ASSERT(tp->t_inpcb); 2849 2850 /* 2851 * Adjust for the SYN bit in sequence space, 2852 * but don't account for it in cwnd calculations. 2853 * This is for the SYN_RECEIVED, non-simultaneous 2854 * SYN case. SYN_SENT and simultaneous SYN are 2855 * treated elsewhere. 2856 */ 2857 if (incforsyn) 2858 tp->snd_una++; 2859 acked = BYTES_THIS_ACK(tp, th); 2860 KASSERT(acked >= 0, ("%s: acked unexepectedly negative " 2861 "(tp->snd_una=%u, th->th_ack=%u, tp=%p, m=%p)", __func__, 2862 tp->snd_una, th->th_ack, tp, m)); 2863 TCPSTAT_ADD(tcps_rcvackpack, nsegs); 2864 TCPSTAT_ADD(tcps_rcvackbyte, acked); 2865 2866 /* 2867 * If we just performed our first retransmit, and the ACK 2868 * arrives within our recovery window, then it was a mistake 2869 * to do the retransmit in the first place. Recover our 2870 * original cwnd and ssthresh, and proceed to transmit where 2871 * we left off. 2872 */ 2873 if (tp->t_rxtshift == 1 && 2874 tp->t_flags & TF_PREVVALID && 2875 tp->t_badrxtwin && 2876 SEQ_LT(to.to_tsecr, tp->t_badrxtwin)) 2877 cc_cong_signal(tp, th, CC_RTO_ERR); 2878 2879 /* 2880 * If we have a timestamp reply, update smoothed 2881 * round trip time. If no timestamp is present but 2882 * transmit timer is running and timed sequence 2883 * number was acked, update smoothed round trip time. 2884 * Since we now have an rtt measurement, cancel the 2885 * timer backoff (cf., Phil Karn's retransmit alg.). 2886 * Recompute the initial retransmit timer. 2887 * 2888 * Some boxes send broken timestamp replies 2889 * during the SYN+ACK phase, ignore 2890 * timestamps of 0 or we could calculate a 2891 * huge RTT and blow up the retransmit timer. 2892 */ 2893 if ((to.to_flags & TOF_TS) != 0 && to.to_tsecr) { 2894 uint32_t t; 2895 2896 t = tcp_ts_getticks() - to.to_tsecr; 2897 if (!tp->t_rttlow || tp->t_rttlow > t) 2898 tp->t_rttlow = t; 2899 tcp_xmit_timer(tp, TCP_TS_TO_TICKS(t) + 1); 2900 } else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) { 2901 if (!tp->t_rttlow || tp->t_rttlow > ticks - tp->t_rtttime) 2902 tp->t_rttlow = ticks - tp->t_rtttime; 2903 tcp_xmit_timer(tp, ticks - tp->t_rtttime); 2904 } 2905 2906 /* 2907 * If all outstanding data is acked, stop retransmit 2908 * timer and remember to restart (more output or persist). 2909 * If there is more data to be acked, restart retransmit 2910 * timer, using current (possibly backed-off) value. 2911 */ 2912 if (th->th_ack == tp->snd_max) { 2913 tcp_timer_activate(tp, TT_REXMT, 0); 2914 needoutput = 1; 2915 } else if (!tcp_timer_active(tp, TT_PERSIST)) 2916 tcp_timer_activate(tp, TT_REXMT, tp->t_rxtcur); 2917 2918 /* 2919 * If no data (only SYN) was ACK'd, 2920 * skip rest of ACK processing. 2921 */ 2922 if (acked == 0) 2923 goto step6; 2924 2925 /* 2926 * Let the congestion control algorithm update congestion 2927 * control related information. This typically means increasing 2928 * the congestion window. 2929 */ 2930 cc_ack_received(tp, th, nsegs, CC_ACK); 2931 2932 SOCKBUF_LOCK(&so->so_snd); 2933 if (acked > sbavail(&so->so_snd)) { 2934 if (tp->snd_wnd >= sbavail(&so->so_snd)) 2935 tp->snd_wnd -= sbavail(&so->so_snd); 2936 else 2937 tp->snd_wnd = 0; 2938 mfree = sbcut_locked(&so->so_snd, 2939 (int)sbavail(&so->so_snd)); 2940 ourfinisacked = 1; 2941 } else { 2942 mfree = sbcut_locked(&so->so_snd, acked); 2943 if (tp->snd_wnd >= (uint32_t) acked) 2944 tp->snd_wnd -= acked; 2945 else 2946 tp->snd_wnd = 0; 2947 ourfinisacked = 0; 2948 } 2949 SOCKBUF_UNLOCK(&so->so_snd); 2950 tp->t_flags |= TF_WAKESOW; 2951 m_freem(mfree); 2952 /* Detect una wraparound. */ 2953 if (!IN_RECOVERY(tp->t_flags) && 2954 SEQ_GT(tp->snd_una, tp->snd_recover) && 2955 SEQ_LEQ(th->th_ack, tp->snd_recover)) 2956 tp->snd_recover = th->th_ack - 1; 2957 /* XXXLAS: Can this be moved up into cc_post_recovery? */ 2958 if (IN_RECOVERY(tp->t_flags) && 2959 SEQ_GEQ(th->th_ack, tp->snd_recover)) { 2960 EXIT_RECOVERY(tp->t_flags); 2961 } 2962 tp->snd_una = th->th_ack; 2963 if (tp->t_flags & TF_SACK_PERMIT) { 2964 if (SEQ_GT(tp->snd_una, tp->snd_recover)) 2965 tp->snd_recover = tp->snd_una; 2966 } 2967 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2968 tp->snd_nxt = tp->snd_una; 2969 2970 switch (tp->t_state) { 2971 /* 2972 * In FIN_WAIT_1 STATE in addition to the processing 2973 * for the ESTABLISHED state if our FIN is now acknowledged 2974 * then enter FIN_WAIT_2. 2975 */ 2976 case TCPS_FIN_WAIT_1: 2977 if (ourfinisacked) { 2978 /* 2979 * If we can't receive any more 2980 * data, then closing user can proceed. 2981 * Starting the timer is contrary to the 2982 * specification, but if we don't get a FIN 2983 * we'll hang forever. 2984 * 2985 * XXXjl: 2986 * we should release the tp also, and use a 2987 * compressed state. 2988 */ 2989 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 2990 soisdisconnected(so); 2991 tcp_timer_activate(tp, TT_2MSL, 2992 (tcp_fast_finwait2_recycle ? 2993 tcp_finwait2_timeout : 2994 TP_MAXIDLE(tp))); 2995 } 2996 tcp_state_change(tp, TCPS_FIN_WAIT_2); 2997 } 2998 break; 2999 3000 /* 3001 * In CLOSING STATE in addition to the processing for 3002 * the ESTABLISHED state if the ACK acknowledges our FIN 3003 * then enter the TIME-WAIT state, otherwise ignore 3004 * the segment. 3005 */ 3006 case TCPS_CLOSING: 3007 if (ourfinisacked) { 3008 tcp_twstart(tp); 3009 m_freem(m); 3010 return; 3011 } 3012 break; 3013 3014 /* 3015 * In LAST_ACK, we may still be waiting for data to drain 3016 * and/or to be acked, as well as for the ack of our FIN. 3017 * If our FIN is now acknowledged, delete the TCB, 3018 * enter the closed state and return. 3019 */ 3020 case TCPS_LAST_ACK: 3021 if (ourfinisacked) { 3022 tp = tcp_close(tp); 3023 goto drop; 3024 } 3025 break; 3026 } 3027 } 3028 3029 step6: 3030 INP_WLOCK_ASSERT(tp->t_inpcb); 3031 3032 /* 3033 * Update window information. 3034 * Don't look at window if no ACK: TAC's send garbage on first SYN. 3035 */ 3036 if ((thflags & TH_ACK) && 3037 (SEQ_LT(tp->snd_wl1, th->th_seq) || 3038 (tp->snd_wl1 == th->th_seq && (SEQ_LT(tp->snd_wl2, th->th_ack) || 3039 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))) { 3040 /* keep track of pure window updates */ 3041 if (tlen == 0 && 3042 tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) 3043 TCPSTAT_INC(tcps_rcvwinupd); 3044 tp->snd_wnd = tiwin; 3045 tp->snd_wl1 = th->th_seq; 3046 tp->snd_wl2 = th->th_ack; 3047 if (tp->snd_wnd > tp->max_sndwnd) 3048 tp->max_sndwnd = tp->snd_wnd; 3049 needoutput = 1; 3050 } 3051 3052 /* 3053 * Process segments with URG. 3054 */ 3055 if ((thflags & TH_URG) && th->th_urp && 3056 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3057 /* 3058 * This is a kludge, but if we receive and accept 3059 * random urgent pointers, we'll crash in 3060 * soreceive. It's hard to imagine someone 3061 * actually wanting to send this much urgent data. 3062 */ 3063 SOCKBUF_LOCK(&so->so_rcv); 3064 if (th->th_urp + sbavail(&so->so_rcv) > sb_max) { 3065 th->th_urp = 0; /* XXX */ 3066 thflags &= ~TH_URG; /* XXX */ 3067 SOCKBUF_UNLOCK(&so->so_rcv); /* XXX */ 3068 goto dodata; /* XXX */ 3069 } 3070 /* 3071 * If this segment advances the known urgent pointer, 3072 * then mark the data stream. This should not happen 3073 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 3074 * a FIN has been received from the remote side. 3075 * In these states we ignore the URG. 3076 * 3077 * According to RFC961 (Assigned Protocols), 3078 * the urgent pointer points to the last octet 3079 * of urgent data. We continue, however, 3080 * to consider it to indicate the first octet 3081 * of data past the urgent section as the original 3082 * spec states (in one of two places). 3083 */ 3084 if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) { 3085 tp->rcv_up = th->th_seq + th->th_urp; 3086 so->so_oobmark = sbavail(&so->so_rcv) + 3087 (tp->rcv_up - tp->rcv_nxt) - 1; 3088 if (so->so_oobmark == 0) 3089 so->so_rcv.sb_state |= SBS_RCVATMARK; 3090 sohasoutofband(so); 3091 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); 3092 } 3093 SOCKBUF_UNLOCK(&so->so_rcv); 3094 /* 3095 * Remove out of band data so doesn't get presented to user. 3096 * This can happen independent of advancing the URG pointer, 3097 * but if two URG's are pending at once, some out-of-band 3098 * data may creep in... ick. 3099 */ 3100 if (th->th_urp <= (uint32_t)tlen && 3101 !(so->so_options & SO_OOBINLINE)) { 3102 /* hdr drop is delayed */ 3103 tcp_pulloutofband(so, th, m, drop_hdrlen); 3104 } 3105 } else { 3106 /* 3107 * If no out of band data is expected, 3108 * pull receive urgent pointer along 3109 * with the receive window. 3110 */ 3111 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) 3112 tp->rcv_up = tp->rcv_nxt; 3113 } 3114 dodata: /* XXX */ 3115 INP_WLOCK_ASSERT(tp->t_inpcb); 3116 3117 /* 3118 * Process the segment text, merging it into the TCP sequencing queue, 3119 * and arranging for acknowledgment of receipt if necessary. 3120 * This process logically involves adjusting tp->rcv_wnd as data 3121 * is presented to the user (this happens in tcp_usrreq.c, 3122 * case PRU_RCVD). If a FIN has already been received on this 3123 * connection then we just ignore the text. 3124 */ 3125 tfo_syn = ((tp->t_state == TCPS_SYN_RECEIVED) && 3126 IS_FASTOPEN(tp->t_flags)); 3127 if ((tlen || (thflags & TH_FIN) || (tfo_syn && tlen > 0)) && 3128 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3129 tcp_seq save_start = th->th_seq; 3130 tcp_seq save_rnxt = tp->rcv_nxt; 3131 int save_tlen = tlen; 3132 m_adj(m, drop_hdrlen); /* delayed header drop */ 3133 /* 3134 * Insert segment which includes th into TCP reassembly queue 3135 * with control block tp. Set thflags to whether reassembly now 3136 * includes a segment with FIN. This handles the common case 3137 * inline (segment is the next to be received on an established 3138 * connection, and the queue is empty), avoiding linkage into 3139 * and removal from the queue and repetition of various 3140 * conversions. 3141 * Set DELACK for segments received in order, but ack 3142 * immediately when segments are out of order (so 3143 * fast retransmit can work). 3144 */ 3145 if (th->th_seq == tp->rcv_nxt && 3146 SEGQ_EMPTY(tp) && 3147 (TCPS_HAVEESTABLISHED(tp->t_state) || 3148 tfo_syn)) { 3149 if (DELAY_ACK(tp, tlen) || tfo_syn) 3150 tp->t_flags |= TF_DELACK; 3151 else 3152 tp->t_flags |= TF_ACKNOW; 3153 tp->rcv_nxt += tlen; 3154 if (tlen && 3155 ((tp->t_flags2 & TF2_FBYTES_COMPLETE) == 0) && 3156 (tp->t_fbyte_in == 0)) { 3157 tp->t_fbyte_in = ticks; 3158 if (tp->t_fbyte_in == 0) 3159 tp->t_fbyte_in = 1; 3160 if (tp->t_fbyte_out && tp->t_fbyte_in) 3161 tp->t_flags2 |= TF2_FBYTES_COMPLETE; 3162 } 3163 thflags = th->th_flags & TH_FIN; 3164 TCPSTAT_INC(tcps_rcvpack); 3165 TCPSTAT_ADD(tcps_rcvbyte, tlen); 3166 SOCKBUF_LOCK(&so->so_rcv); 3167 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) 3168 m_freem(m); 3169 else 3170 sbappendstream_locked(&so->so_rcv, m, 0); 3171 SOCKBUF_UNLOCK(&so->so_rcv); 3172 tp->t_flags |= TF_WAKESOR; 3173 } else { 3174 /* 3175 * XXX: Due to the header drop above "th" is 3176 * theoretically invalid by now. Fortunately 3177 * m_adj() doesn't actually frees any mbufs 3178 * when trimming from the head. 3179 */ 3180 tcp_seq temp = save_start; 3181 thflags = tcp_reass(tp, th, &temp, &tlen, m); 3182 tp->t_flags |= TF_ACKNOW; 3183 } 3184 if ((tp->t_flags & TF_SACK_PERMIT) && 3185 (save_tlen > 0) && 3186 TCPS_HAVEESTABLISHED(tp->t_state)) { 3187 if ((tlen == 0) && (SEQ_LT(save_start, save_rnxt))) { 3188 /* 3189 * DSACK actually handled in the fastpath 3190 * above. 3191 */ 3192 tcp_update_sack_list(tp, save_start, 3193 save_start + save_tlen); 3194 } else if ((tlen > 0) && SEQ_GT(tp->rcv_nxt, save_rnxt)) { 3195 if ((tp->rcv_numsacks >= 1) && 3196 (tp->sackblks[0].end == save_start)) { 3197 /* 3198 * Partial overlap, recorded at todrop 3199 * above. 3200 */ 3201 tcp_update_sack_list(tp, 3202 tp->sackblks[0].start, 3203 tp->sackblks[0].end); 3204 } else { 3205 tcp_update_dsack_list(tp, save_start, 3206 save_start + save_tlen); 3207 } 3208 } else if (tlen >= save_tlen) { 3209 /* Update of sackblks. */ 3210 tcp_update_dsack_list(tp, save_start, 3211 save_start + save_tlen); 3212 } else if (tlen > 0) { 3213 tcp_update_dsack_list(tp, save_start, 3214 save_start + tlen); 3215 } 3216 } 3217 #if 0 3218 /* 3219 * Note the amount of data that peer has sent into 3220 * our window, in order to estimate the sender's 3221 * buffer size. 3222 * XXX: Unused. 3223 */ 3224 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt)) 3225 len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); 3226 else 3227 len = so->so_rcv.sb_hiwat; 3228 #endif 3229 } else { 3230 m_freem(m); 3231 thflags &= ~TH_FIN; 3232 } 3233 3234 /* 3235 * If FIN is received ACK the FIN and let the user know 3236 * that the connection is closing. 3237 */ 3238 if (thflags & TH_FIN) { 3239 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3240 socantrcvmore(so); 3241 /* The socket upcall is handled by socantrcvmore. */ 3242 tp->t_flags &= ~TF_WAKESOR; 3243 /* 3244 * If connection is half-synchronized 3245 * (ie NEEDSYN flag on) then delay ACK, 3246 * so it may be piggybacked when SYN is sent. 3247 * Otherwise, since we received a FIN then no 3248 * more input can be expected, send ACK now. 3249 */ 3250 if (tp->t_flags & TF_NEEDSYN) 3251 tp->t_flags |= TF_DELACK; 3252 else 3253 tp->t_flags |= TF_ACKNOW; 3254 tp->rcv_nxt++; 3255 } 3256 switch (tp->t_state) { 3257 /* 3258 * In SYN_RECEIVED and ESTABLISHED STATES 3259 * enter the CLOSE_WAIT state. 3260 */ 3261 case TCPS_SYN_RECEIVED: 3262 tp->t_starttime = ticks; 3263 /* FALLTHROUGH */ 3264 case TCPS_ESTABLISHED: 3265 tcp_state_change(tp, TCPS_CLOSE_WAIT); 3266 break; 3267 3268 /* 3269 * If still in FIN_WAIT_1 STATE FIN has not been acked so 3270 * enter the CLOSING state. 3271 */ 3272 case TCPS_FIN_WAIT_1: 3273 tcp_state_change(tp, TCPS_CLOSING); 3274 break; 3275 3276 /* 3277 * In FIN_WAIT_2 state enter the TIME_WAIT state, 3278 * starting the time-wait timer, turning off the other 3279 * standard timers. 3280 */ 3281 case TCPS_FIN_WAIT_2: 3282 tcp_twstart(tp); 3283 return; 3284 } 3285 } 3286 #ifdef TCPDEBUG 3287 if (so->so_options & SO_DEBUG) 3288 tcp_trace(TA_INPUT, ostate, tp, (void *)tcp_saveipgen, 3289 &tcp_savetcp, 0); 3290 #endif 3291 TCP_PROBE3(debug__input, tp, th, m); 3292 3293 /* 3294 * Return any desired output. 3295 */ 3296 if (needoutput || (tp->t_flags & TF_ACKNOW)) 3297 (void) tp->t_fb->tfb_tcp_output(tp); 3298 3299 check_delack: 3300 INP_WLOCK_ASSERT(tp->t_inpcb); 3301 3302 if (tp->t_flags & TF_DELACK) { 3303 tp->t_flags &= ~TF_DELACK; 3304 tcp_timer_activate(tp, TT_DELACK, tcp_delacktime); 3305 } 3306 tcp_handle_wakeup(tp, so); 3307 INP_WUNLOCK(tp->t_inpcb); 3308 return; 3309 3310 dropafterack: 3311 /* 3312 * Generate an ACK dropping incoming segment if it occupies 3313 * sequence space, where the ACK reflects our state. 3314 * 3315 * We can now skip the test for the RST flag since all 3316 * paths to this code happen after packets containing 3317 * RST have been dropped. 3318 * 3319 * In the SYN-RECEIVED state, don't send an ACK unless the 3320 * segment we received passes the SYN-RECEIVED ACK test. 3321 * If it fails send a RST. This breaks the loop in the 3322 * "LAND" DoS attack, and also prevents an ACK storm 3323 * between two listening ports that have been sent forged 3324 * SYN segments, each with the source address of the other. 3325 */ 3326 if (tp->t_state == TCPS_SYN_RECEIVED && (thflags & TH_ACK) && 3327 (SEQ_GT(tp->snd_una, th->th_ack) || 3328 SEQ_GT(th->th_ack, tp->snd_max)) ) { 3329 rstreason = BANDLIM_RST_OPENPORT; 3330 goto dropwithreset; 3331 } 3332 #ifdef TCPDEBUG 3333 if (so->so_options & SO_DEBUG) 3334 tcp_trace(TA_DROP, ostate, tp, (void *)tcp_saveipgen, 3335 &tcp_savetcp, 0); 3336 #endif 3337 TCP_PROBE3(debug__input, tp, th, m); 3338 tp->t_flags |= TF_ACKNOW; 3339 (void) tp->t_fb->tfb_tcp_output(tp); 3340 tcp_handle_wakeup(tp, so); 3341 INP_WUNLOCK(tp->t_inpcb); 3342 m_freem(m); 3343 return; 3344 3345 dropwithreset: 3346 if (tp != NULL) { 3347 tcp_dropwithreset(m, th, tp, tlen, rstreason); 3348 tcp_handle_wakeup(tp, so); 3349 INP_WUNLOCK(tp->t_inpcb); 3350 } else 3351 tcp_dropwithreset(m, th, NULL, tlen, rstreason); 3352 return; 3353 3354 drop: 3355 /* 3356 * Drop space held by incoming segment and return. 3357 */ 3358 #ifdef TCPDEBUG 3359 if (tp == NULL || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 3360 tcp_trace(TA_DROP, ostate, tp, (void *)tcp_saveipgen, 3361 &tcp_savetcp, 0); 3362 #endif 3363 TCP_PROBE3(debug__input, tp, th, m); 3364 if (tp != NULL) { 3365 tcp_handle_wakeup(tp, so); 3366 INP_WUNLOCK(tp->t_inpcb); 3367 } 3368 m_freem(m); 3369 } 3370 3371 /* 3372 * Issue RST and make ACK acceptable to originator of segment. 3373 * The mbuf must still include the original packet header. 3374 * tp may be NULL. 3375 */ 3376 void 3377 tcp_dropwithreset(struct mbuf *m, struct tcphdr *th, struct tcpcb *tp, 3378 int tlen, int rstreason) 3379 { 3380 #ifdef INET 3381 struct ip *ip; 3382 #endif 3383 #ifdef INET6 3384 struct ip6_hdr *ip6; 3385 #endif 3386 3387 if (tp != NULL) { 3388 INP_LOCK_ASSERT(tp->t_inpcb); 3389 } 3390 3391 /* Don't bother if destination was broadcast/multicast. */ 3392 if ((th->th_flags & TH_RST) || m->m_flags & (M_BCAST|M_MCAST)) 3393 goto drop; 3394 #ifdef INET6 3395 if (mtod(m, struct ip *)->ip_v == 6) { 3396 ip6 = mtod(m, struct ip6_hdr *); 3397 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 3398 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) 3399 goto drop; 3400 /* IPv6 anycast check is done at tcp6_input() */ 3401 } 3402 #endif 3403 #if defined(INET) && defined(INET6) 3404 else 3405 #endif 3406 #ifdef INET 3407 { 3408 ip = mtod(m, struct ip *); 3409 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || 3410 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 3411 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || 3412 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 3413 goto drop; 3414 } 3415 #endif 3416 3417 /* Perform bandwidth limiting. */ 3418 if (badport_bandlim(rstreason) < 0) 3419 goto drop; 3420 3421 /* tcp_respond consumes the mbuf chain. */ 3422 if (th->th_flags & TH_ACK) { 3423 tcp_respond(tp, mtod(m, void *), th, m, (tcp_seq)0, 3424 th->th_ack, TH_RST); 3425 } else { 3426 if (th->th_flags & TH_SYN) 3427 tlen++; 3428 if (th->th_flags & TH_FIN) 3429 tlen++; 3430 tcp_respond(tp, mtod(m, void *), th, m, th->th_seq+tlen, 3431 (tcp_seq)0, TH_RST|TH_ACK); 3432 } 3433 return; 3434 drop: 3435 m_freem(m); 3436 } 3437 3438 /* 3439 * Parse TCP options and place in tcpopt. 3440 */ 3441 void 3442 tcp_dooptions(struct tcpopt *to, u_char *cp, int cnt, int flags) 3443 { 3444 int opt, optlen; 3445 3446 to->to_flags = 0; 3447 for (; cnt > 0; cnt -= optlen, cp += optlen) { 3448 opt = cp[0]; 3449 if (opt == TCPOPT_EOL) 3450 break; 3451 if (opt == TCPOPT_NOP) 3452 optlen = 1; 3453 else { 3454 if (cnt < 2) 3455 break; 3456 optlen = cp[1]; 3457 if (optlen < 2 || optlen > cnt) 3458 break; 3459 } 3460 switch (opt) { 3461 case TCPOPT_MAXSEG: 3462 if (optlen != TCPOLEN_MAXSEG) 3463 continue; 3464 if (!(flags & TO_SYN)) 3465 continue; 3466 to->to_flags |= TOF_MSS; 3467 bcopy((char *)cp + 2, 3468 (char *)&to->to_mss, sizeof(to->to_mss)); 3469 to->to_mss = ntohs(to->to_mss); 3470 break; 3471 case TCPOPT_WINDOW: 3472 if (optlen != TCPOLEN_WINDOW) 3473 continue; 3474 if (!(flags & TO_SYN)) 3475 continue; 3476 to->to_flags |= TOF_SCALE; 3477 to->to_wscale = min(cp[2], TCP_MAX_WINSHIFT); 3478 break; 3479 case TCPOPT_TIMESTAMP: 3480 if (optlen != TCPOLEN_TIMESTAMP) 3481 continue; 3482 to->to_flags |= TOF_TS; 3483 bcopy((char *)cp + 2, 3484 (char *)&to->to_tsval, sizeof(to->to_tsval)); 3485 to->to_tsval = ntohl(to->to_tsval); 3486 bcopy((char *)cp + 6, 3487 (char *)&to->to_tsecr, sizeof(to->to_tsecr)); 3488 to->to_tsecr = ntohl(to->to_tsecr); 3489 break; 3490 case TCPOPT_SIGNATURE: 3491 /* 3492 * In order to reply to a host which has set the 3493 * TCP_SIGNATURE option in its initial SYN, we have 3494 * to record the fact that the option was observed 3495 * here for the syncache code to perform the correct 3496 * response. 3497 */ 3498 if (optlen != TCPOLEN_SIGNATURE) 3499 continue; 3500 to->to_flags |= TOF_SIGNATURE; 3501 to->to_signature = cp + 2; 3502 break; 3503 case TCPOPT_SACK_PERMITTED: 3504 if (optlen != TCPOLEN_SACK_PERMITTED) 3505 continue; 3506 if (!(flags & TO_SYN)) 3507 continue; 3508 if (!V_tcp_do_sack) 3509 continue; 3510 to->to_flags |= TOF_SACKPERM; 3511 break; 3512 case TCPOPT_SACK: 3513 if (optlen <= 2 || (optlen - 2) % TCPOLEN_SACK != 0) 3514 continue; 3515 if (flags & TO_SYN) 3516 continue; 3517 to->to_flags |= TOF_SACK; 3518 to->to_nsacks = (optlen - 2) / TCPOLEN_SACK; 3519 to->to_sacks = cp + 2; 3520 TCPSTAT_INC(tcps_sack_rcv_blocks); 3521 break; 3522 case TCPOPT_FAST_OPEN: 3523 /* 3524 * Cookie length validation is performed by the 3525 * server side cookie checking code or the client 3526 * side cookie cache update code. 3527 */ 3528 if (!(flags & TO_SYN)) 3529 continue; 3530 if (!V_tcp_fastopen_client_enable && 3531 !V_tcp_fastopen_server_enable) 3532 continue; 3533 to->to_flags |= TOF_FASTOPEN; 3534 to->to_tfo_len = optlen - 2; 3535 to->to_tfo_cookie = to->to_tfo_len ? cp + 2 : NULL; 3536 break; 3537 default: 3538 continue; 3539 } 3540 } 3541 } 3542 3543 /* 3544 * Pull out of band byte out of a segment so 3545 * it doesn't appear in the user's data queue. 3546 * It is still reflected in the segment length for 3547 * sequencing purposes. 3548 */ 3549 void 3550 tcp_pulloutofband(struct socket *so, struct tcphdr *th, struct mbuf *m, 3551 int off) 3552 { 3553 int cnt = off + th->th_urp - 1; 3554 3555 while (cnt >= 0) { 3556 if (m->m_len > cnt) { 3557 char *cp = mtod(m, caddr_t) + cnt; 3558 struct tcpcb *tp = sototcpcb(so); 3559 3560 INP_WLOCK_ASSERT(tp->t_inpcb); 3561 3562 tp->t_iobc = *cp; 3563 tp->t_oobflags |= TCPOOB_HAVEDATA; 3564 bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); 3565 m->m_len--; 3566 if (m->m_flags & M_PKTHDR) 3567 m->m_pkthdr.len--; 3568 return; 3569 } 3570 cnt -= m->m_len; 3571 m = m->m_next; 3572 if (m == NULL) 3573 break; 3574 } 3575 panic("tcp_pulloutofband"); 3576 } 3577 3578 /* 3579 * Collect new round-trip time estimate 3580 * and update averages and current timeout. 3581 */ 3582 void 3583 tcp_xmit_timer(struct tcpcb *tp, int rtt) 3584 { 3585 int delta; 3586 3587 INP_WLOCK_ASSERT(tp->t_inpcb); 3588 3589 TCPSTAT_INC(tcps_rttupdated); 3590 tp->t_rttupdated++; 3591 #ifdef STATS 3592 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_RTT, 3593 imax(0, rtt * 1000 / hz)); 3594 #endif 3595 if ((tp->t_srtt != 0) && (tp->t_rxtshift <= TCP_RTT_INVALIDATE)) { 3596 /* 3597 * srtt is stored as fixed point with 5 bits after the 3598 * binary point (i.e., scaled by 8). The following magic 3599 * is equivalent to the smoothing algorithm in rfc793 with 3600 * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed 3601 * point). Adjust rtt to origin 0. 3602 */ 3603 delta = ((rtt - 1) << TCP_DELTA_SHIFT) 3604 - (tp->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT)); 3605 3606 if ((tp->t_srtt += delta) <= 0) 3607 tp->t_srtt = 1; 3608 3609 /* 3610 * We accumulate a smoothed rtt variance (actually, a 3611 * smoothed mean difference), then set the retransmit 3612 * timer to smoothed rtt + 4 times the smoothed variance. 3613 * rttvar is stored as fixed point with 4 bits after the 3614 * binary point (scaled by 16). The following is 3615 * equivalent to rfc793 smoothing with an alpha of .75 3616 * (rttvar = rttvar*3/4 + |delta| / 4). This replaces 3617 * rfc793's wired-in beta. 3618 */ 3619 if (delta < 0) 3620 delta = -delta; 3621 delta -= tp->t_rttvar >> (TCP_RTTVAR_SHIFT - TCP_DELTA_SHIFT); 3622 if ((tp->t_rttvar += delta) <= 0) 3623 tp->t_rttvar = 1; 3624 if (tp->t_rttbest > tp->t_srtt + tp->t_rttvar) 3625 tp->t_rttbest = tp->t_srtt + tp->t_rttvar; 3626 } else { 3627 /* 3628 * No rtt measurement yet - use the unsmoothed rtt. 3629 * Set the variance to half the rtt (so our first 3630 * retransmit happens at 3*rtt). 3631 */ 3632 tp->t_srtt = rtt << TCP_RTT_SHIFT; 3633 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1); 3634 tp->t_rttbest = tp->t_srtt + tp->t_rttvar; 3635 } 3636 tp->t_rtttime = 0; 3637 tp->t_rxtshift = 0; 3638 3639 /* 3640 * the retransmit should happen at rtt + 4 * rttvar. 3641 * Because of the way we do the smoothing, srtt and rttvar 3642 * will each average +1/2 tick of bias. When we compute 3643 * the retransmit timer, we want 1/2 tick of rounding and 3644 * 1 extra tick because of +-1/2 tick uncertainty in the 3645 * firing of the timer. The bias will give us exactly the 3646 * 1.5 tick we need. But, because the bias is 3647 * statistical, we have to test that we don't drop below 3648 * the minimum feasible timer (which is 2 ticks). 3649 */ 3650 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), 3651 max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX); 3652 3653 /* 3654 * We received an ack for a packet that wasn't retransmitted; 3655 * it is probably safe to discard any error indications we've 3656 * received recently. This isn't quite right, but close enough 3657 * for now (a route might have failed after we sent a segment, 3658 * and the return path might not be symmetrical). 3659 */ 3660 tp->t_softerror = 0; 3661 } 3662 3663 /* 3664 * Determine a reasonable value for maxseg size. 3665 * If the route is known, check route for mtu. 3666 * If none, use an mss that can be handled on the outgoing interface 3667 * without forcing IP to fragment. If no route is found, route has no mtu, 3668 * or the destination isn't local, use a default, hopefully conservative 3669 * size (usually 512 or the default IP max size, but no more than the mtu 3670 * of the interface), as we can't discover anything about intervening 3671 * gateways or networks. We also initialize the congestion/slow start 3672 * window to be a single segment if the destination isn't local. 3673 * While looking at the routing entry, we also initialize other path-dependent 3674 * parameters from pre-set or cached values in the routing entry. 3675 * 3676 * NOTE that resulting t_maxseg doesn't include space for TCP options or 3677 * IP options, e.g. IPSEC data, since length of this data may vary, and 3678 * thus it is calculated for every segment separately in tcp_output(). 3679 * 3680 * NOTE that this routine is only called when we process an incoming 3681 * segment, or an ICMP need fragmentation datagram. Outgoing SYN/ACK MSS 3682 * settings are handled in tcp_mssopt(). 3683 */ 3684 void 3685 tcp_mss_update(struct tcpcb *tp, int offer, int mtuoffer, 3686 struct hc_metrics_lite *metricptr, struct tcp_ifcap *cap) 3687 { 3688 int mss = 0; 3689 uint32_t maxmtu = 0; 3690 struct inpcb *inp = tp->t_inpcb; 3691 struct hc_metrics_lite metrics; 3692 #ifdef INET6 3693 int isipv6 = ((inp->inp_vflag & INP_IPV6) != 0) ? 1 : 0; 3694 size_t min_protoh = isipv6 ? 3695 sizeof (struct ip6_hdr) + sizeof (struct tcphdr) : 3696 sizeof (struct tcpiphdr); 3697 #else 3698 size_t min_protoh = sizeof(struct tcpiphdr); 3699 #endif 3700 3701 INP_WLOCK_ASSERT(tp->t_inpcb); 3702 3703 if (tp->t_port) 3704 min_protoh += V_tcp_udp_tunneling_overhead; 3705 if (mtuoffer != -1) { 3706 KASSERT(offer == -1, ("%s: conflict", __func__)); 3707 offer = mtuoffer - min_protoh; 3708 } 3709 3710 /* Initialize. */ 3711 #ifdef INET6 3712 if (isipv6) { 3713 maxmtu = tcp_maxmtu6(&inp->inp_inc, cap); 3714 tp->t_maxseg = V_tcp_v6mssdflt; 3715 } 3716 #endif 3717 #if defined(INET) && defined(INET6) 3718 else 3719 #endif 3720 #ifdef INET 3721 { 3722 maxmtu = tcp_maxmtu(&inp->inp_inc, cap); 3723 tp->t_maxseg = V_tcp_mssdflt; 3724 } 3725 #endif 3726 3727 /* 3728 * No route to sender, stay with default mss and return. 3729 */ 3730 if (maxmtu == 0) { 3731 /* 3732 * In case we return early we need to initialize metrics 3733 * to a defined state as tcp_hc_get() would do for us 3734 * if there was no cache hit. 3735 */ 3736 if (metricptr != NULL) 3737 bzero(metricptr, sizeof(struct hc_metrics_lite)); 3738 return; 3739 } 3740 3741 /* What have we got? */ 3742 switch (offer) { 3743 case 0: 3744 /* 3745 * Offer == 0 means that there was no MSS on the SYN 3746 * segment, in this case we use tcp_mssdflt as 3747 * already assigned to t_maxseg above. 3748 */ 3749 offer = tp->t_maxseg; 3750 break; 3751 3752 case -1: 3753 /* 3754 * Offer == -1 means that we didn't receive SYN yet. 3755 */ 3756 /* FALLTHROUGH */ 3757 3758 default: 3759 /* 3760 * Prevent DoS attack with too small MSS. Round up 3761 * to at least minmss. 3762 */ 3763 offer = max(offer, V_tcp_minmss); 3764 } 3765 3766 /* 3767 * rmx information is now retrieved from tcp_hostcache. 3768 */ 3769 tcp_hc_get(&inp->inp_inc, &metrics); 3770 if (metricptr != NULL) 3771 bcopy(&metrics, metricptr, sizeof(struct hc_metrics_lite)); 3772 3773 /* 3774 * If there's a discovered mtu in tcp hostcache, use it. 3775 * Else, use the link mtu. 3776 */ 3777 if (metrics.rmx_mtu) 3778 mss = min(metrics.rmx_mtu, maxmtu) - min_protoh; 3779 else { 3780 #ifdef INET6 3781 if (isipv6) { 3782 mss = maxmtu - min_protoh; 3783 if (!V_path_mtu_discovery && 3784 !in6_localaddr(&inp->in6p_faddr)) 3785 mss = min(mss, V_tcp_v6mssdflt); 3786 } 3787 #endif 3788 #if defined(INET) && defined(INET6) 3789 else 3790 #endif 3791 #ifdef INET 3792 { 3793 mss = maxmtu - min_protoh; 3794 if (!V_path_mtu_discovery && 3795 !in_localaddr(inp->inp_faddr)) 3796 mss = min(mss, V_tcp_mssdflt); 3797 } 3798 #endif 3799 /* 3800 * XXX - The above conditional (mss = maxmtu - min_protoh) 3801 * probably violates the TCP spec. 3802 * The problem is that, since we don't know the 3803 * other end's MSS, we are supposed to use a conservative 3804 * default. But, if we do that, then MTU discovery will 3805 * never actually take place, because the conservative 3806 * default is much less than the MTUs typically seen 3807 * on the Internet today. For the moment, we'll sweep 3808 * this under the carpet. 3809 * 3810 * The conservative default might not actually be a problem 3811 * if the only case this occurs is when sending an initial 3812 * SYN with options and data to a host we've never talked 3813 * to before. Then, they will reply with an MSS value which 3814 * will get recorded and the new parameters should get 3815 * recomputed. For Further Study. 3816 */ 3817 } 3818 mss = min(mss, offer); 3819 3820 /* 3821 * Sanity check: make sure that maxseg will be large 3822 * enough to allow some data on segments even if the 3823 * all the option space is used (40bytes). Otherwise 3824 * funny things may happen in tcp_output. 3825 * 3826 * XXXGL: shouldn't we reserve space for IP/IPv6 options? 3827 */ 3828 mss = max(mss, 64); 3829 3830 tp->t_maxseg = mss; 3831 } 3832 3833 void 3834 tcp_mss(struct tcpcb *tp, int offer) 3835 { 3836 int mss; 3837 uint32_t bufsize; 3838 struct inpcb *inp; 3839 struct socket *so; 3840 struct hc_metrics_lite metrics; 3841 struct tcp_ifcap cap; 3842 3843 KASSERT(tp != NULL, ("%s: tp == NULL", __func__)); 3844 3845 bzero(&cap, sizeof(cap)); 3846 tcp_mss_update(tp, offer, -1, &metrics, &cap); 3847 3848 mss = tp->t_maxseg; 3849 inp = tp->t_inpcb; 3850 3851 /* 3852 * If there's a pipesize, change the socket buffer to that size, 3853 * don't change if sb_hiwat is different than default (then it 3854 * has been changed on purpose with setsockopt). 3855 * Make the socket buffers an integral number of mss units; 3856 * if the mss is larger than the socket buffer, decrease the mss. 3857 */ 3858 so = inp->inp_socket; 3859 SOCKBUF_LOCK(&so->so_snd); 3860 if ((so->so_snd.sb_hiwat == V_tcp_sendspace) && metrics.rmx_sendpipe) 3861 bufsize = metrics.rmx_sendpipe; 3862 else 3863 bufsize = so->so_snd.sb_hiwat; 3864 if (bufsize < mss) 3865 mss = bufsize; 3866 else { 3867 bufsize = roundup(bufsize, mss); 3868 if (bufsize > sb_max) 3869 bufsize = sb_max; 3870 if (bufsize > so->so_snd.sb_hiwat) 3871 (void)sbreserve_locked(&so->so_snd, bufsize, so, NULL); 3872 } 3873 SOCKBUF_UNLOCK(&so->so_snd); 3874 /* 3875 * Sanity check: make sure that maxseg will be large 3876 * enough to allow some data on segments even if the 3877 * all the option space is used (40bytes). Otherwise 3878 * funny things may happen in tcp_output. 3879 * 3880 * XXXGL: shouldn't we reserve space for IP/IPv6 options? 3881 */ 3882 tp->t_maxseg = max(mss, 64); 3883 3884 SOCKBUF_LOCK(&so->so_rcv); 3885 if ((so->so_rcv.sb_hiwat == V_tcp_recvspace) && metrics.rmx_recvpipe) 3886 bufsize = metrics.rmx_recvpipe; 3887 else 3888 bufsize = so->so_rcv.sb_hiwat; 3889 if (bufsize > mss) { 3890 bufsize = roundup(bufsize, mss); 3891 if (bufsize > sb_max) 3892 bufsize = sb_max; 3893 if (bufsize > so->so_rcv.sb_hiwat) 3894 (void)sbreserve_locked(&so->so_rcv, bufsize, so, NULL); 3895 } 3896 SOCKBUF_UNLOCK(&so->so_rcv); 3897 3898 /* Check the interface for TSO capabilities. */ 3899 if (cap.ifcap & CSUM_TSO) { 3900 tp->t_flags |= TF_TSO; 3901 tp->t_tsomax = cap.tsomax; 3902 tp->t_tsomaxsegcount = cap.tsomaxsegcount; 3903 tp->t_tsomaxsegsize = cap.tsomaxsegsize; 3904 } 3905 } 3906 3907 /* 3908 * Determine the MSS option to send on an outgoing SYN. 3909 */ 3910 int 3911 tcp_mssopt(struct in_conninfo *inc) 3912 { 3913 int mss = 0; 3914 uint32_t thcmtu = 0; 3915 uint32_t maxmtu = 0; 3916 size_t min_protoh; 3917 3918 KASSERT(inc != NULL, ("tcp_mssopt with NULL in_conninfo pointer")); 3919 3920 #ifdef INET6 3921 if (inc->inc_flags & INC_ISIPV6) { 3922 mss = V_tcp_v6mssdflt; 3923 maxmtu = tcp_maxmtu6(inc, NULL); 3924 min_protoh = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 3925 } 3926 #endif 3927 #if defined(INET) && defined(INET6) 3928 else 3929 #endif 3930 #ifdef INET 3931 { 3932 mss = V_tcp_mssdflt; 3933 maxmtu = tcp_maxmtu(inc, NULL); 3934 min_protoh = sizeof(struct tcpiphdr); 3935 } 3936 #endif 3937 #if defined(INET6) || defined(INET) 3938 thcmtu = tcp_hc_getmtu(inc); /* IPv4 and IPv6 */ 3939 #endif 3940 3941 if (maxmtu && thcmtu) 3942 mss = min(maxmtu, thcmtu) - min_protoh; 3943 else if (maxmtu || thcmtu) 3944 mss = max(maxmtu, thcmtu) - min_protoh; 3945 3946 return (mss); 3947 } 3948 3949 void 3950 tcp_do_prr_ack(struct tcpcb *tp, struct tcphdr *th, struct tcpopt *to) 3951 { 3952 int snd_cnt = 0, limit = 0, del_data = 0, pipe = 0; 3953 int maxseg = tcp_maxseg(tp); 3954 3955 INP_WLOCK_ASSERT(tp->t_inpcb); 3956 3957 /* 3958 * Compute the amount of data that this ACK is indicating 3959 * (del_data) and an estimate of how many bytes are in the 3960 * network. 3961 */ 3962 del_data = tp->sackhint.delivered_data; 3963 if (V_tcp_do_newsack) 3964 pipe = tcp_compute_pipe(tp); 3965 else 3966 pipe = (tp->snd_nxt - tp->snd_fack) + tp->sackhint.sack_bytes_rexmit; 3967 tp->sackhint.prr_delivered += del_data; 3968 /* 3969 * Proportional Rate Reduction 3970 */ 3971 if (pipe >= tp->snd_ssthresh) { 3972 if (tp->sackhint.recover_fs == 0) 3973 tp->sackhint.recover_fs = 3974 imax(1, tp->snd_nxt - tp->snd_una); 3975 snd_cnt = howmany((long)tp->sackhint.prr_delivered * 3976 tp->snd_ssthresh, tp->sackhint.recover_fs) - 3977 tp->sackhint.prr_out; 3978 } else { 3979 if (V_tcp_do_prr_conservative) 3980 limit = tp->sackhint.prr_delivered - 3981 tp->sackhint.prr_out; 3982 else 3983 limit = imax(tp->sackhint.prr_delivered - 3984 tp->sackhint.prr_out, del_data) + 3985 maxseg; 3986 snd_cnt = imin((tp->snd_ssthresh - pipe), limit); 3987 } 3988 snd_cnt = imax(snd_cnt, 0) / maxseg; 3989 /* 3990 * Send snd_cnt new data into the network in response to this ack. 3991 * If there is going to be a SACK retransmission, adjust snd_cwnd 3992 * accordingly. 3993 */ 3994 if (IN_FASTRECOVERY(tp->t_flags)) { 3995 tp->snd_cwnd = imax(maxseg, tp->snd_nxt - tp->snd_recover + 3996 tp->sackhint.sack_bytes_rexmit + (snd_cnt * maxseg)); 3997 } else if (IN_CONGRECOVERY(tp->t_flags)) 3998 tp->snd_cwnd = imax(maxseg, pipe - del_data + 3999 (snd_cnt * maxseg)); 4000 } 4001 4002 /* 4003 * On a partial ack arrives, force the retransmission of the 4004 * next unacknowledged segment. Do not clear tp->t_dupacks. 4005 * By setting snd_nxt to ti_ack, this forces retransmission timer to 4006 * be started again. 4007 */ 4008 void 4009 tcp_newreno_partial_ack(struct tcpcb *tp, struct tcphdr *th) 4010 { 4011 tcp_seq onxt = tp->snd_nxt; 4012 uint32_t ocwnd = tp->snd_cwnd; 4013 u_int maxseg = tcp_maxseg(tp); 4014 4015 INP_WLOCK_ASSERT(tp->t_inpcb); 4016 4017 tcp_timer_activate(tp, TT_REXMT, 0); 4018 tp->t_rtttime = 0; 4019 tp->snd_nxt = th->th_ack; 4020 /* 4021 * Set snd_cwnd to one segment beyond acknowledged offset. 4022 * (tp->snd_una has not yet been updated when this function is called.) 4023 */ 4024 tp->snd_cwnd = maxseg + BYTES_THIS_ACK(tp, th); 4025 tp->t_flags |= TF_ACKNOW; 4026 (void) tp->t_fb->tfb_tcp_output(tp); 4027 tp->snd_cwnd = ocwnd; 4028 if (SEQ_GT(onxt, tp->snd_nxt)) 4029 tp->snd_nxt = onxt; 4030 /* 4031 * Partial window deflation. Relies on fact that tp->snd_una 4032 * not updated yet. 4033 */ 4034 if (tp->snd_cwnd > BYTES_THIS_ACK(tp, th)) 4035 tp->snd_cwnd -= BYTES_THIS_ACK(tp, th); 4036 else 4037 tp->snd_cwnd = 0; 4038 tp->snd_cwnd += maxseg; 4039 } 4040 4041 int 4042 tcp_compute_pipe(struct tcpcb *tp) 4043 { 4044 return (tp->snd_max - tp->snd_una + 4045 tp->sackhint.sack_bytes_rexmit - 4046 tp->sackhint.sacked_bytes); 4047 } 4048 4049 uint32_t 4050 tcp_compute_initwnd(uint32_t maxseg) 4051 { 4052 /* 4053 * Calculate the Initial Window, also used as Restart Window 4054 * 4055 * RFC5681 Section 3.1 specifies the default conservative values. 4056 * RFC3390 specifies slightly more aggressive values. 4057 * RFC6928 increases it to ten segments. 4058 * Support for user specified value for initial flight size. 4059 */ 4060 if (V_tcp_initcwnd_segments) 4061 return min(V_tcp_initcwnd_segments * maxseg, 4062 max(2 * maxseg, V_tcp_initcwnd_segments * 1460)); 4063 else if (V_tcp_do_rfc3390) 4064 return min(4 * maxseg, max(2 * maxseg, 4380)); 4065 else { 4066 /* Per RFC5681 Section 3.1 */ 4067 if (maxseg > 2190) 4068 return (2 * maxseg); 4069 else if (maxseg > 1095) 4070 return (3 * maxseg); 4071 else 4072 return (4 * maxseg); 4073 } 4074 } 4075