1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995 5 * The Regents of the University of California. All rights reserved. 6 * Copyright (c) 2007-2008,2010 7 * Swinburne University of Technology, Melbourne, Australia. 8 * Copyright (c) 2009-2010 Lawrence Stewart <lstewart@freebsd.org> 9 * Copyright (c) 2010 The FreeBSD Foundation 10 * Copyright (c) 2010-2011 Juniper Networks, Inc. 11 * All rights reserved. 12 * 13 * Portions of this software were developed at the Centre for Advanced Internet 14 * Architectures, Swinburne University of Technology, by Lawrence Stewart, 15 * James Healy and David Hayes, made possible in part by a grant from the Cisco 16 * University Research Program Fund at Community Foundation Silicon Valley. 17 * 18 * Portions of this software were developed at the Centre for Advanced 19 * Internet Architectures, Swinburne University of Technology, Melbourne, 20 * Australia by David Hayes under sponsorship from the FreeBSD Foundation. 21 * 22 * Portions of this software were developed by Robert N. M. Watson under 23 * contract to Juniper Networks, Inc. 24 * 25 * Redistribution and use in source and binary forms, with or without 26 * modification, are permitted provided that the following conditions 27 * are met: 28 * 1. Redistributions of source code must retain the above copyright 29 * notice, this list of conditions and the following disclaimer. 30 * 2. Redistributions in binary form must reproduce the above copyright 31 * notice, this list of conditions and the following disclaimer in the 32 * documentation and/or other materials provided with the distribution. 33 * 3. Neither the name of the University nor the names of its contributors 34 * may be used to endorse or promote products derived from this software 35 * without specific prior written permission. 36 * 37 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 38 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 39 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 40 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 41 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 42 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 43 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 44 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 45 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 46 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 47 * SUCH DAMAGE. 48 * 49 * @(#)tcp_input.c 8.12 (Berkeley) 5/24/95 50 */ 51 52 #include <sys/cdefs.h> 53 __FBSDID("$FreeBSD$"); 54 55 #include "opt_inet.h" 56 #include "opt_inet6.h" 57 #include "opt_ipsec.h" 58 #include "opt_tcpdebug.h" 59 60 #include <sys/param.h> 61 #include <sys/arb.h> 62 #include <sys/kernel.h> 63 #ifdef TCP_HHOOK 64 #include <sys/hhook.h> 65 #endif 66 #include <sys/malloc.h> 67 #include <sys/mbuf.h> 68 #include <sys/proc.h> /* for proc0 declaration */ 69 #include <sys/protosw.h> 70 #include <sys/qmath.h> 71 #include <sys/sdt.h> 72 #include <sys/signalvar.h> 73 #include <sys/socket.h> 74 #include <sys/socketvar.h> 75 #include <sys/sysctl.h> 76 #include <sys/syslog.h> 77 #include <sys/systm.h> 78 #include <sys/stats.h> 79 80 #include <machine/cpu.h> /* before tcp_seq.h, for tcp_random18() */ 81 82 #include <vm/uma.h> 83 84 #include <net/if.h> 85 #include <net/if_var.h> 86 #include <net/route.h> 87 #include <net/vnet.h> 88 89 #define TCPSTATES /* for logging */ 90 91 #include <netinet/in.h> 92 #include <netinet/in_kdtrace.h> 93 #include <netinet/in_pcb.h> 94 #include <netinet/in_systm.h> 95 #include <netinet/ip.h> 96 #include <netinet/ip_icmp.h> /* required for icmp_var.h */ 97 #include <netinet/icmp_var.h> /* for ICMP_BANDLIM */ 98 #include <netinet/ip_var.h> 99 #include <netinet/ip_options.h> 100 #include <netinet/ip6.h> 101 #include <netinet/icmp6.h> 102 #include <netinet6/in6_pcb.h> 103 #include <netinet6/in6_var.h> 104 #include <netinet6/ip6_var.h> 105 #include <netinet6/nd6.h> 106 #include <netinet/tcp.h> 107 #include <netinet/tcp_fsm.h> 108 #include <netinet/tcp_log_buf.h> 109 #include <netinet/tcp_seq.h> 110 #include <netinet/tcp_timer.h> 111 #include <netinet/tcp_var.h> 112 #include <netinet6/tcp6_var.h> 113 #include <netinet/tcpip.h> 114 #include <netinet/cc/cc.h> 115 #include <netinet/tcp_fastopen.h> 116 #ifdef TCPPCAP 117 #include <netinet/tcp_pcap.h> 118 #endif 119 #include <netinet/tcp_syncache.h> 120 #ifdef TCPDEBUG 121 #include <netinet/tcp_debug.h> 122 #endif /* TCPDEBUG */ 123 #ifdef TCP_OFFLOAD 124 #include <netinet/tcp_offload.h> 125 #endif 126 #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(bool, blackhole_local) = false; 148 #define V_blackhole_local VNET(blackhole_local) 149 SYSCTL_BOOL(_net_inet_tcp, OID_AUTO, blackhole_local, CTLFLAG_VNET | 150 CTLFLAG_RW, &VNET_NAME(blackhole_local), false, 151 "Enforce net.inet.tcp.blackhole for locally originated packets"); 152 153 VNET_DEFINE(int, tcp_delack_enabled) = 1; 154 SYSCTL_INT(_net_inet_tcp, OID_AUTO, delayed_ack, CTLFLAG_VNET | CTLFLAG_RW, 155 &VNET_NAME(tcp_delack_enabled), 0, 156 "Delay ACK to try and piggyback it onto a data packet"); 157 158 VNET_DEFINE(int, drop_synfin) = 0; 159 SYSCTL_INT(_net_inet_tcp, OID_AUTO, drop_synfin, CTLFLAG_VNET | CTLFLAG_RW, 160 &VNET_NAME(drop_synfin), 0, 161 "Drop TCP packets with SYN+FIN set"); 162 163 VNET_DEFINE(int, tcp_do_prr_conservative) = 0; 164 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_prr_conservative, CTLFLAG_VNET | CTLFLAG_RW, 165 &VNET_NAME(tcp_do_prr_conservative), 0, 166 "Do conservative Proportional Rate Reduction"); 167 168 VNET_DEFINE(int, tcp_do_prr) = 1; 169 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_prr, CTLFLAG_VNET | CTLFLAG_RW, 170 &VNET_NAME(tcp_do_prr), 1, 171 "Enable Proportional Rate Reduction per RFC 6937"); 172 173 VNET_DEFINE(int, tcp_do_lrd) = 0; 174 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_lrd, CTLFLAG_VNET | CTLFLAG_RW, 175 &VNET_NAME(tcp_do_lrd), 1, 176 "Perform Lost Retransmission Detection"); 177 178 VNET_DEFINE(int, tcp_do_newcwv) = 0; 179 SYSCTL_INT(_net_inet_tcp, OID_AUTO, newcwv, CTLFLAG_VNET | CTLFLAG_RW, 180 &VNET_NAME(tcp_do_newcwv), 0, 181 "Enable New Congestion Window Validation per RFC7661"); 182 183 VNET_DEFINE(int, tcp_do_rfc3042) = 1; 184 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3042, CTLFLAG_VNET | CTLFLAG_RW, 185 &VNET_NAME(tcp_do_rfc3042), 0, 186 "Enable RFC 3042 (Limited Transmit)"); 187 188 VNET_DEFINE(int, tcp_do_rfc3390) = 1; 189 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3390, CTLFLAG_VNET | CTLFLAG_RW, 190 &VNET_NAME(tcp_do_rfc3390), 0, 191 "Enable RFC 3390 (Increasing TCP's Initial Congestion Window)"); 192 193 VNET_DEFINE(int, tcp_initcwnd_segments) = 10; 194 SYSCTL_INT(_net_inet_tcp, OID_AUTO, initcwnd_segments, 195 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(tcp_initcwnd_segments), 0, 196 "Slow-start flight size (initial congestion window) in number of segments"); 197 198 VNET_DEFINE(int, tcp_do_rfc3465) = 1; 199 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3465, CTLFLAG_VNET | CTLFLAG_RW, 200 &VNET_NAME(tcp_do_rfc3465), 0, 201 "Enable RFC 3465 (Appropriate Byte Counting)"); 202 203 VNET_DEFINE(int, tcp_abc_l_var) = 2; 204 SYSCTL_INT(_net_inet_tcp, OID_AUTO, abc_l_var, CTLFLAG_VNET | CTLFLAG_RW, 205 &VNET_NAME(tcp_abc_l_var), 2, 206 "Cap the max cwnd increment during slow-start to this number of segments"); 207 208 static SYSCTL_NODE(_net_inet_tcp, OID_AUTO, ecn, 209 CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 210 "TCP ECN"); 211 212 VNET_DEFINE(int, tcp_do_ecn) = 2; 213 SYSCTL_INT(_net_inet_tcp_ecn, OID_AUTO, enable, CTLFLAG_VNET | CTLFLAG_RW, 214 &VNET_NAME(tcp_do_ecn), 0, 215 "TCP ECN support"); 216 217 VNET_DEFINE(int, tcp_ecn_maxretries) = 1; 218 SYSCTL_INT(_net_inet_tcp_ecn, OID_AUTO, maxretries, CTLFLAG_VNET | CTLFLAG_RW, 219 &VNET_NAME(tcp_ecn_maxretries), 0, 220 "Max retries before giving up on ECN"); 221 222 VNET_DEFINE(int, tcp_insecure_syn) = 0; 223 SYSCTL_INT(_net_inet_tcp, OID_AUTO, insecure_syn, CTLFLAG_VNET | CTLFLAG_RW, 224 &VNET_NAME(tcp_insecure_syn), 0, 225 "Follow RFC793 instead of RFC5961 criteria for accepting SYN packets"); 226 227 VNET_DEFINE(int, tcp_insecure_rst) = 0; 228 SYSCTL_INT(_net_inet_tcp, OID_AUTO, insecure_rst, CTLFLAG_VNET | CTLFLAG_RW, 229 &VNET_NAME(tcp_insecure_rst), 0, 230 "Follow RFC793 instead of RFC5961 criteria for accepting RST packets"); 231 232 VNET_DEFINE(int, tcp_recvspace) = 1024*64; 233 #define V_tcp_recvspace VNET(tcp_recvspace) 234 SYSCTL_INT(_net_inet_tcp, TCPCTL_RECVSPACE, recvspace, CTLFLAG_VNET | CTLFLAG_RW, 235 &VNET_NAME(tcp_recvspace), 0, "Initial receive socket buffer size"); 236 237 VNET_DEFINE(int, tcp_do_autorcvbuf) = 1; 238 SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_auto, CTLFLAG_VNET | CTLFLAG_RW, 239 &VNET_NAME(tcp_do_autorcvbuf), 0, 240 "Enable automatic receive buffer sizing"); 241 242 VNET_DEFINE(int, tcp_autorcvbuf_max) = 2*1024*1024; 243 SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_max, CTLFLAG_VNET | CTLFLAG_RW, 244 &VNET_NAME(tcp_autorcvbuf_max), 0, 245 "Max size of automatic receive buffer"); 246 247 VNET_DEFINE(struct inpcbinfo, tcbinfo); 248 249 /* 250 * TCP statistics are stored in an array of counter(9)s, which size matches 251 * size of struct tcpstat. TCP running connection count is a regular array. 252 */ 253 VNET_PCPUSTAT_DEFINE(struct tcpstat, tcpstat); 254 SYSCTL_VNET_PCPUSTAT(_net_inet_tcp, TCPCTL_STATS, stats, struct tcpstat, 255 tcpstat, "TCP statistics (struct tcpstat, netinet/tcp_var.h)"); 256 VNET_DEFINE(counter_u64_t, tcps_states[TCP_NSTATES]); 257 SYSCTL_COUNTER_U64_ARRAY(_net_inet_tcp, TCPCTL_STATES, states, CTLFLAG_RD | 258 CTLFLAG_VNET, &VNET_NAME(tcps_states)[0], TCP_NSTATES, 259 "TCP connection counts by TCP state"); 260 261 /* 262 * Kernel module interface for updating tcpstat. The first argument is an index 263 * into tcpstat treated as an array. 264 */ 265 void 266 kmod_tcpstat_add(int statnum, int val) 267 { 268 269 counter_u64_add(VNET(tcpstat)[statnum], val); 270 } 271 272 #ifdef TCP_HHOOK 273 /* 274 * Wrapper for the TCP established input helper hook. 275 */ 276 void 277 hhook_run_tcp_est_in(struct tcpcb *tp, struct tcphdr *th, struct tcpopt *to) 278 { 279 struct tcp_hhook_data hhook_data; 280 281 if (V_tcp_hhh[HHOOK_TCP_EST_IN]->hhh_nhooks > 0) { 282 hhook_data.tp = tp; 283 hhook_data.th = th; 284 hhook_data.to = to; 285 286 hhook_run_hooks(V_tcp_hhh[HHOOK_TCP_EST_IN], &hhook_data, 287 tp->osd); 288 } 289 } 290 #endif 291 292 /* 293 * CC wrapper hook functions 294 */ 295 void 296 cc_ack_received(struct tcpcb *tp, struct tcphdr *th, uint16_t nsegs, 297 uint16_t type) 298 { 299 #ifdef STATS 300 int32_t gput; 301 #endif 302 303 INP_WLOCK_ASSERT(tp->t_inpcb); 304 305 tp->ccv->nsegs = nsegs; 306 tp->ccv->bytes_this_ack = BYTES_THIS_ACK(tp, th); 307 if ((!V_tcp_do_newcwv && (tp->snd_cwnd <= tp->snd_wnd)) || 308 (V_tcp_do_newcwv && (tp->snd_cwnd <= tp->snd_wnd) && 309 (tp->snd_cwnd < (tcp_compute_pipe(tp) * 2)))) 310 tp->ccv->flags |= CCF_CWND_LIMITED; 311 else 312 tp->ccv->flags &= ~CCF_CWND_LIMITED; 313 314 if (type == CC_ACK) { 315 #ifdef STATS 316 stats_voi_update_abs_s32(tp->t_stats, VOI_TCP_CALCFRWINDIFF, 317 ((int32_t)tp->snd_cwnd) - tp->snd_wnd); 318 if (!IN_RECOVERY(tp->t_flags)) 319 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_ACKLEN, 320 tp->ccv->bytes_this_ack / (tcp_maxseg(tp) * nsegs)); 321 if ((tp->t_flags & TF_GPUTINPROG) && 322 SEQ_GEQ(th->th_ack, tp->gput_ack)) { 323 /* 324 * Compute goodput in bits per millisecond. 325 */ 326 gput = (((int64_t)(th->th_ack - tp->gput_seq)) << 3) / 327 max(1, tcp_ts_getticks() - tp->gput_ts); 328 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_GPUT, 329 gput); 330 /* 331 * XXXLAS: This is a temporary hack, and should be 332 * chained off VOI_TCP_GPUT when stats(9) grows an API 333 * to deal with chained VOIs. 334 */ 335 if (tp->t_stats_gput_prev > 0) 336 stats_voi_update_abs_s32(tp->t_stats, 337 VOI_TCP_GPUT_ND, 338 ((gput - tp->t_stats_gput_prev) * 100) / 339 tp->t_stats_gput_prev); 340 tp->t_flags &= ~TF_GPUTINPROG; 341 tp->t_stats_gput_prev = gput; 342 } 343 #endif /* STATS */ 344 if (tp->snd_cwnd > tp->snd_ssthresh) { 345 tp->t_bytes_acked += tp->ccv->bytes_this_ack; 346 if (tp->t_bytes_acked >= tp->snd_cwnd) { 347 tp->t_bytes_acked -= tp->snd_cwnd; 348 tp->ccv->flags |= CCF_ABC_SENTAWND; 349 } 350 } else { 351 tp->ccv->flags &= ~CCF_ABC_SENTAWND; 352 tp->t_bytes_acked = 0; 353 } 354 } 355 356 if (CC_ALGO(tp)->ack_received != NULL) { 357 /* XXXLAS: Find a way to live without this */ 358 tp->ccv->curack = th->th_ack; 359 CC_ALGO(tp)->ack_received(tp->ccv, type); 360 } 361 #ifdef STATS 362 stats_voi_update_abs_ulong(tp->t_stats, VOI_TCP_LCWIN, tp->snd_cwnd); 363 #endif 364 } 365 366 void 367 cc_conn_init(struct tcpcb *tp) 368 { 369 struct hc_metrics_lite metrics; 370 struct inpcb *inp = tp->t_inpcb; 371 u_int maxseg; 372 int rtt; 373 374 INP_WLOCK_ASSERT(tp->t_inpcb); 375 376 tcp_hc_get(&inp->inp_inc, &metrics); 377 maxseg = tcp_maxseg(tp); 378 379 if (tp->t_srtt == 0 && (rtt = metrics.rmx_rtt)) { 380 tp->t_srtt = rtt; 381 tp->t_rttbest = tp->t_srtt + TCP_RTT_SCALE; 382 TCPSTAT_INC(tcps_usedrtt); 383 if (metrics.rmx_rttvar) { 384 tp->t_rttvar = metrics.rmx_rttvar; 385 TCPSTAT_INC(tcps_usedrttvar); 386 } else { 387 /* default variation is +- 1 rtt */ 388 tp->t_rttvar = 389 tp->t_srtt * TCP_RTTVAR_SCALE / TCP_RTT_SCALE; 390 } 391 TCPT_RANGESET(tp->t_rxtcur, 392 ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1, 393 tp->t_rttmin, TCPTV_REXMTMAX); 394 } 395 if (metrics.rmx_ssthresh) { 396 /* 397 * There's some sort of gateway or interface 398 * buffer limit on the path. Use this to set 399 * the slow start threshold, but set the 400 * threshold to no less than 2*mss. 401 */ 402 tp->snd_ssthresh = max(2 * maxseg, metrics.rmx_ssthresh); 403 TCPSTAT_INC(tcps_usedssthresh); 404 } 405 406 /* 407 * Set the initial slow-start flight size. 408 * 409 * If a SYN or SYN/ACK was lost and retransmitted, we have to 410 * reduce the initial CWND to one segment as congestion is likely 411 * requiring us to be cautious. 412 */ 413 if (tp->snd_cwnd == 1) 414 tp->snd_cwnd = maxseg; /* SYN(-ACK) lost */ 415 else 416 tp->snd_cwnd = tcp_compute_initwnd(maxseg); 417 418 if (CC_ALGO(tp)->conn_init != NULL) 419 CC_ALGO(tp)->conn_init(tp->ccv); 420 } 421 422 void inline 423 cc_cong_signal(struct tcpcb *tp, struct tcphdr *th, uint32_t type) 424 { 425 INP_WLOCK_ASSERT(tp->t_inpcb); 426 427 #ifdef STATS 428 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_CSIG, type); 429 #endif 430 431 switch(type) { 432 case CC_NDUPACK: 433 if (!IN_FASTRECOVERY(tp->t_flags)) { 434 tp->snd_recover = tp->snd_max; 435 if (tp->t_flags2 & TF2_ECN_PERMIT) 436 tp->t_flags2 |= TF2_ECN_SND_CWR; 437 } 438 break; 439 case CC_ECN: 440 if (!IN_CONGRECOVERY(tp->t_flags) || 441 /* 442 * Allow ECN reaction on ACK to CWR, if 443 * that data segment was also CE marked. 444 */ 445 SEQ_GEQ(th->th_ack, tp->snd_recover)) { 446 EXIT_CONGRECOVERY(tp->t_flags); 447 TCPSTAT_INC(tcps_ecn_rcwnd); 448 tp->snd_recover = tp->snd_max + 1; 449 if (tp->t_flags2 & TF2_ECN_PERMIT) 450 tp->t_flags2 |= TF2_ECN_SND_CWR; 451 } 452 break; 453 case CC_RTO: 454 tp->t_dupacks = 0; 455 tp->t_bytes_acked = 0; 456 EXIT_RECOVERY(tp->t_flags); 457 if (tp->t_flags2 & TF2_ECN_PERMIT) 458 tp->t_flags2 |= TF2_ECN_SND_CWR; 459 break; 460 case CC_RTO_ERR: 461 TCPSTAT_INC(tcps_sndrexmitbad); 462 /* RTO was unnecessary, so reset everything. */ 463 tp->snd_cwnd = tp->snd_cwnd_prev; 464 tp->snd_ssthresh = tp->snd_ssthresh_prev; 465 tp->snd_recover = tp->snd_recover_prev; 466 if (tp->t_flags & TF_WASFRECOVERY) 467 ENTER_FASTRECOVERY(tp->t_flags); 468 if (tp->t_flags & TF_WASCRECOVERY) 469 ENTER_CONGRECOVERY(tp->t_flags); 470 tp->snd_nxt = tp->snd_max; 471 tp->t_flags &= ~TF_PREVVALID; 472 tp->t_badrxtwin = 0; 473 break; 474 } 475 476 if (CC_ALGO(tp)->cong_signal != NULL) { 477 if (th != NULL) 478 tp->ccv->curack = th->th_ack; 479 CC_ALGO(tp)->cong_signal(tp->ccv, type); 480 } 481 } 482 483 void inline 484 cc_post_recovery(struct tcpcb *tp, struct tcphdr *th) 485 { 486 INP_WLOCK_ASSERT(tp->t_inpcb); 487 488 /* XXXLAS: KASSERT that we're in recovery? */ 489 490 if (CC_ALGO(tp)->post_recovery != NULL) { 491 tp->ccv->curack = th->th_ack; 492 CC_ALGO(tp)->post_recovery(tp->ccv); 493 } 494 /* XXXLAS: EXIT_RECOVERY ? */ 495 tp->t_bytes_acked = 0; 496 tp->sackhint.delivered_data = 0; 497 tp->sackhint.prr_out = 0; 498 } 499 500 /* 501 * Indicate whether this ack should be delayed. We can delay the ack if 502 * following conditions are met: 503 * - There is no delayed ack timer in progress. 504 * - Our last ack wasn't a 0-sized window. We never want to delay 505 * the ack that opens up a 0-sized window. 506 * - LRO wasn't used for this segment. We make sure by checking that the 507 * segment size is not larger than the MSS. 508 */ 509 #define DELAY_ACK(tp, tlen) \ 510 ((!tcp_timer_active(tp, TT_DELACK) && \ 511 (tp->t_flags & TF_RXWIN0SENT) == 0) && \ 512 (tlen <= tp->t_maxseg) && \ 513 (V_tcp_delack_enabled || (tp->t_flags & TF_NEEDSYN))) 514 515 void inline 516 cc_ecnpkt_handler_flags(struct tcpcb *tp, uint16_t flags, uint8_t iptos) 517 { 518 INP_WLOCK_ASSERT(tp->t_inpcb); 519 520 if (CC_ALGO(tp)->ecnpkt_handler != NULL) { 521 switch (iptos & IPTOS_ECN_MASK) { 522 case IPTOS_ECN_CE: 523 tp->ccv->flags |= CCF_IPHDR_CE; 524 break; 525 case IPTOS_ECN_ECT0: 526 /* FALLTHROUGH */ 527 case IPTOS_ECN_ECT1: 528 /* FALLTHROUGH */ 529 case IPTOS_ECN_NOTECT: 530 tp->ccv->flags &= ~CCF_IPHDR_CE; 531 break; 532 } 533 534 if (flags & TH_CWR) 535 tp->ccv->flags |= CCF_TCPHDR_CWR; 536 else 537 tp->ccv->flags &= ~CCF_TCPHDR_CWR; 538 539 CC_ALGO(tp)->ecnpkt_handler(tp->ccv); 540 541 if (tp->ccv->flags & CCF_ACKNOW) { 542 tcp_timer_activate(tp, TT_DELACK, tcp_delacktime); 543 tp->t_flags |= TF_ACKNOW; 544 } 545 } 546 } 547 548 void inline 549 cc_ecnpkt_handler(struct tcpcb *tp, struct tcphdr *th, uint8_t iptos) 550 { 551 cc_ecnpkt_handler_flags(tp, th->th_flags, iptos); 552 } 553 554 /* 555 * TCP input handling is split into multiple parts: 556 * tcp6_input is a thin wrapper around tcp_input for the extended 557 * ip6_protox[] call format in ip6_input 558 * tcp_input handles primary segment validation, inpcb lookup and 559 * SYN processing on listen sockets 560 * tcp_do_segment processes the ACK and text of the segment for 561 * establishing, established and closing connections 562 */ 563 #ifdef INET6 564 int 565 tcp6_input_with_port(struct mbuf **mp, int *offp, int proto, uint16_t port) 566 { 567 struct mbuf *m; 568 struct in6_ifaddr *ia6; 569 struct ip6_hdr *ip6; 570 571 m = *mp; 572 if (m->m_len < *offp + sizeof(struct tcphdr)) { 573 m = m_pullup(m, *offp + sizeof(struct tcphdr)); 574 if (m == NULL) { 575 *mp = m; 576 TCPSTAT_INC(tcps_rcvshort); 577 return (IPPROTO_DONE); 578 } 579 } 580 581 /* 582 * draft-itojun-ipv6-tcp-to-anycast 583 * better place to put this in? 584 */ 585 ip6 = mtod(m, struct ip6_hdr *); 586 ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */, false); 587 if (ia6 && (ia6->ia6_flags & IN6_IFF_ANYCAST)) { 588 icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR, 589 (caddr_t)&ip6->ip6_dst - (caddr_t)ip6); 590 *mp = NULL; 591 return (IPPROTO_DONE); 592 } 593 594 *mp = m; 595 return (tcp_input_with_port(mp, offp, proto, port)); 596 } 597 598 int 599 tcp6_input(struct mbuf **mp, int *offp, int proto) 600 { 601 602 return(tcp6_input_with_port(mp, offp, proto, 0)); 603 } 604 #endif /* INET6 */ 605 606 int 607 tcp_input_with_port(struct mbuf **mp, int *offp, int proto, uint16_t port) 608 { 609 struct mbuf *m = *mp; 610 struct tcphdr *th = NULL; 611 struct ip *ip = NULL; 612 struct inpcb *inp = NULL; 613 struct tcpcb *tp = NULL; 614 struct socket *so = NULL; 615 u_char *optp = NULL; 616 int off0; 617 int optlen = 0; 618 #ifdef INET 619 int len; 620 uint8_t ipttl; 621 #endif 622 int tlen = 0, off; 623 int drop_hdrlen; 624 int thflags; 625 int rstreason = 0; /* For badport_bandlim accounting purposes */ 626 int lookupflag; 627 uint8_t iptos; 628 struct m_tag *fwd_tag = NULL; 629 #ifdef INET6 630 struct ip6_hdr *ip6 = NULL; 631 int isipv6; 632 #else 633 const void *ip6 = NULL; 634 #endif /* INET6 */ 635 struct tcpopt to; /* options in this segment */ 636 char *s = NULL; /* address and port logging */ 637 #ifdef TCPDEBUG 638 /* 639 * The size of tcp_saveipgen must be the size of the max ip header, 640 * now IPv6. 641 */ 642 u_char tcp_saveipgen[IP6_HDR_LEN]; 643 struct tcphdr tcp_savetcp; 644 short ostate = 0; 645 #endif 646 647 NET_EPOCH_ASSERT(); 648 649 #ifdef INET6 650 isipv6 = (mtod(m, struct ip *)->ip_v == 6) ? 1 : 0; 651 #endif 652 653 off0 = *offp; 654 m = *mp; 655 *mp = NULL; 656 to.to_flags = 0; 657 TCPSTAT_INC(tcps_rcvtotal); 658 659 #ifdef INET6 660 if (isipv6) { 661 ip6 = mtod(m, struct ip6_hdr *); 662 th = (struct tcphdr *)((caddr_t)ip6 + off0); 663 tlen = sizeof(*ip6) + ntohs(ip6->ip6_plen) - off0; 664 if (port) 665 goto skip6_csum; 666 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID_IPV6) { 667 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 668 th->th_sum = m->m_pkthdr.csum_data; 669 else 670 th->th_sum = in6_cksum_pseudo(ip6, tlen, 671 IPPROTO_TCP, m->m_pkthdr.csum_data); 672 th->th_sum ^= 0xffff; 673 } else 674 th->th_sum = in6_cksum(m, IPPROTO_TCP, off0, tlen); 675 if (th->th_sum) { 676 TCPSTAT_INC(tcps_rcvbadsum); 677 goto drop; 678 } 679 skip6_csum: 680 /* 681 * Be proactive about unspecified IPv6 address in source. 682 * As we use all-zero to indicate unbounded/unconnected pcb, 683 * unspecified IPv6 address can be used to confuse us. 684 * 685 * Note that packets with unspecified IPv6 destination is 686 * already dropped in ip6_input. 687 */ 688 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 689 /* XXX stat */ 690 goto drop; 691 } 692 iptos = IPV6_TRAFFIC_CLASS(ip6); 693 } 694 #endif 695 #if defined(INET) && defined(INET6) 696 else 697 #endif 698 #ifdef INET 699 { 700 /* 701 * Get IP and TCP header together in first mbuf. 702 * Note: IP leaves IP header in first mbuf. 703 */ 704 if (off0 > sizeof (struct ip)) { 705 ip_stripoptions(m); 706 off0 = sizeof(struct ip); 707 } 708 if (m->m_len < sizeof (struct tcpiphdr)) { 709 if ((m = m_pullup(m, sizeof (struct tcpiphdr))) 710 == NULL) { 711 TCPSTAT_INC(tcps_rcvshort); 712 return (IPPROTO_DONE); 713 } 714 } 715 ip = mtod(m, struct ip *); 716 th = (struct tcphdr *)((caddr_t)ip + off0); 717 tlen = ntohs(ip->ip_len) - off0; 718 719 iptos = ip->ip_tos; 720 if (port) 721 goto skip_csum; 722 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) { 723 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 724 th->th_sum = m->m_pkthdr.csum_data; 725 else 726 th->th_sum = in_pseudo(ip->ip_src.s_addr, 727 ip->ip_dst.s_addr, 728 htonl(m->m_pkthdr.csum_data + tlen + 729 IPPROTO_TCP)); 730 th->th_sum ^= 0xffff; 731 } else { 732 struct ipovly *ipov = (struct ipovly *)ip; 733 734 /* 735 * Checksum extended TCP header and data. 736 */ 737 len = off0 + tlen; 738 ipttl = ip->ip_ttl; 739 bzero(ipov->ih_x1, sizeof(ipov->ih_x1)); 740 ipov->ih_len = htons(tlen); 741 th->th_sum = in_cksum(m, len); 742 /* Reset length for SDT probes. */ 743 ip->ip_len = htons(len); 744 /* Reset TOS bits */ 745 ip->ip_tos = iptos; 746 /* Re-initialization for later version check */ 747 ip->ip_ttl = ipttl; 748 ip->ip_v = IPVERSION; 749 ip->ip_hl = off0 >> 2; 750 } 751 skip_csum: 752 if (th->th_sum && (port == 0)) { 753 TCPSTAT_INC(tcps_rcvbadsum); 754 goto drop; 755 } 756 } 757 #endif /* INET */ 758 759 /* 760 * Check that TCP offset makes sense, 761 * pull out TCP options and adjust length. XXX 762 */ 763 off = th->th_off << 2; 764 if (off < sizeof (struct tcphdr) || off > tlen) { 765 TCPSTAT_INC(tcps_rcvbadoff); 766 goto drop; 767 } 768 tlen -= off; /* tlen is used instead of ti->ti_len */ 769 if (off > sizeof (struct tcphdr)) { 770 #ifdef INET6 771 if (isipv6) { 772 if (m->m_len < off0 + off) { 773 m = m_pullup(m, off0 + off); 774 if (m == NULL) { 775 TCPSTAT_INC(tcps_rcvshort); 776 return (IPPROTO_DONE); 777 } 778 } 779 ip6 = mtod(m, struct ip6_hdr *); 780 th = (struct tcphdr *)((caddr_t)ip6 + off0); 781 } 782 #endif 783 #if defined(INET) && defined(INET6) 784 else 785 #endif 786 #ifdef INET 787 { 788 if (m->m_len < sizeof(struct ip) + off) { 789 if ((m = m_pullup(m, sizeof (struct ip) + off)) 790 == NULL) { 791 TCPSTAT_INC(tcps_rcvshort); 792 return (IPPROTO_DONE); 793 } 794 ip = mtod(m, struct ip *); 795 th = (struct tcphdr *)((caddr_t)ip + off0); 796 } 797 } 798 #endif 799 optlen = off - sizeof (struct tcphdr); 800 optp = (u_char *)(th + 1); 801 } 802 thflags = th->th_flags; 803 804 /* 805 * Convert TCP protocol specific fields to host format. 806 */ 807 tcp_fields_to_host(th); 808 809 /* 810 * Delay dropping TCP, IP headers, IPv6 ext headers, and TCP options. 811 */ 812 drop_hdrlen = off0 + off; 813 814 /* 815 * Grab info from PACKET_TAG_IPFORWARD tag prepended to the chain. 816 */ 817 if ( 818 #ifdef INET6 819 (isipv6 && (m->m_flags & M_IP6_NEXTHOP)) 820 #ifdef INET 821 || (!isipv6 && (m->m_flags & M_IP_NEXTHOP)) 822 #endif 823 #endif 824 #if defined(INET) && !defined(INET6) 825 (m->m_flags & M_IP_NEXTHOP) 826 #endif 827 ) 828 fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL); 829 830 /* 831 * For initial SYN packets we don't need write lock on matching 832 * PCB, be it a listening one or a synchronized one. The packet 833 * shall not modify its state. 834 */ 835 lookupflag = (thflags & (TH_ACK|TH_SYN)) == TH_SYN ? 836 INPLOOKUP_RLOCKPCB : INPLOOKUP_WLOCKPCB; 837 findpcb: 838 #ifdef INET6 839 if (isipv6 && fwd_tag != NULL) { 840 struct sockaddr_in6 *next_hop6; 841 842 next_hop6 = (struct sockaddr_in6 *)(fwd_tag + 1); 843 /* 844 * Transparently forwarded. Pretend to be the destination. 845 * Already got one like this? 846 */ 847 inp = in6_pcblookup_mbuf(&V_tcbinfo, 848 &ip6->ip6_src, th->th_sport, &ip6->ip6_dst, th->th_dport, 849 lookupflag, m->m_pkthdr.rcvif, m); 850 if (!inp) { 851 /* 852 * It's new. Try to find the ambushing socket. 853 * Because we've rewritten the destination address, 854 * any hardware-generated hash is ignored. 855 */ 856 inp = in6_pcblookup(&V_tcbinfo, &ip6->ip6_src, 857 th->th_sport, &next_hop6->sin6_addr, 858 next_hop6->sin6_port ? ntohs(next_hop6->sin6_port) : 859 th->th_dport, INPLOOKUP_WILDCARD | lookupflag, 860 m->m_pkthdr.rcvif); 861 } 862 } else if (isipv6) { 863 inp = in6_pcblookup_mbuf(&V_tcbinfo, &ip6->ip6_src, 864 th->th_sport, &ip6->ip6_dst, th->th_dport, 865 INPLOOKUP_WILDCARD | lookupflag, m->m_pkthdr.rcvif, m); 866 } 867 #endif /* INET6 */ 868 #if defined(INET6) && defined(INET) 869 else 870 #endif 871 #ifdef INET 872 if (fwd_tag != NULL) { 873 struct sockaddr_in *next_hop; 874 875 next_hop = (struct sockaddr_in *)(fwd_tag+1); 876 /* 877 * Transparently forwarded. Pretend to be the destination. 878 * already got one like this? 879 */ 880 inp = in_pcblookup_mbuf(&V_tcbinfo, ip->ip_src, th->th_sport, 881 ip->ip_dst, th->th_dport, lookupflag, m->m_pkthdr.rcvif, m); 882 if (!inp) { 883 /* 884 * It's new. Try to find the ambushing socket. 885 * Because we've rewritten the destination address, 886 * any hardware-generated hash is ignored. 887 */ 888 inp = in_pcblookup(&V_tcbinfo, ip->ip_src, 889 th->th_sport, next_hop->sin_addr, 890 next_hop->sin_port ? ntohs(next_hop->sin_port) : 891 th->th_dport, INPLOOKUP_WILDCARD | lookupflag, 892 m->m_pkthdr.rcvif); 893 } 894 } else 895 inp = in_pcblookup_mbuf(&V_tcbinfo, ip->ip_src, 896 th->th_sport, ip->ip_dst, th->th_dport, 897 INPLOOKUP_WILDCARD | lookupflag, m->m_pkthdr.rcvif, m); 898 #endif /* INET */ 899 900 /* 901 * If the INPCB does not exist then all data in the incoming 902 * segment is discarded and an appropriate RST is sent back. 903 * XXX MRT Send RST using which routing table? 904 */ 905 if (inp == NULL) { 906 /* 907 * Log communication attempts to ports that are not 908 * in use. 909 */ 910 if ((V_tcp_log_in_vain == 1 && (thflags & TH_SYN)) || 911 V_tcp_log_in_vain == 2) { 912 if ((s = tcp_log_vain(NULL, th, (void *)ip, ip6))) 913 log(LOG_INFO, "%s; %s: Connection attempt " 914 "to closed port\n", s, __func__); 915 } 916 /* 917 * When blackholing do not respond with a RST but 918 * completely ignore the segment and drop it. 919 */ 920 if (((V_blackhole == 1 && (thflags & TH_SYN)) || 921 V_blackhole == 2) && (V_blackhole_local || 922 #ifdef INET6 923 isipv6 ? !in6_localaddr(&ip6->ip6_src) : 924 #endif 925 #ifdef INET 926 !in_localip(ip->ip_src) 927 #else 928 true 929 #endif 930 )) 931 goto dropunlock; 932 933 rstreason = BANDLIM_RST_CLOSEDPORT; 934 goto dropwithreset; 935 } 936 INP_LOCK_ASSERT(inp); 937 /* 938 * While waiting for inp lock during the lookup, another thread 939 * can have dropped the inpcb, in which case we need to loop back 940 * and try to find a new inpcb to deliver to. 941 */ 942 if (inp->inp_flags & INP_DROPPED) { 943 INP_UNLOCK(inp); 944 inp = NULL; 945 goto findpcb; 946 } 947 if ((inp->inp_flowtype == M_HASHTYPE_NONE) && 948 (M_HASHTYPE_GET(m) != M_HASHTYPE_NONE) && 949 ((inp->inp_socket == NULL) || !SOLISTENING(inp->inp_socket))) { 950 inp->inp_flowid = m->m_pkthdr.flowid; 951 inp->inp_flowtype = M_HASHTYPE_GET(m); 952 } 953 #if defined(IPSEC) || defined(IPSEC_SUPPORT) 954 #ifdef INET6 955 if (isipv6 && IPSEC_ENABLED(ipv6) && 956 IPSEC_CHECK_POLICY(ipv6, m, inp) != 0) { 957 goto dropunlock; 958 } 959 #ifdef INET 960 else 961 #endif 962 #endif /* INET6 */ 963 #ifdef INET 964 if (IPSEC_ENABLED(ipv4) && 965 IPSEC_CHECK_POLICY(ipv4, m, inp) != 0) { 966 goto dropunlock; 967 } 968 #endif /* INET */ 969 #endif /* IPSEC */ 970 971 /* 972 * Check the minimum TTL for socket. 973 */ 974 if (inp->inp_ip_minttl != 0) { 975 #ifdef INET6 976 if (isipv6) { 977 if (inp->inp_ip_minttl > ip6->ip6_hlim) 978 goto dropunlock; 979 } else 980 #endif 981 if (inp->inp_ip_minttl > ip->ip_ttl) 982 goto dropunlock; 983 } 984 985 /* 986 * A previous connection in TIMEWAIT state is supposed to catch stray 987 * or duplicate segments arriving late. If this segment was a 988 * legitimate new connection attempt, the old INPCB gets removed and 989 * we can try again to find a listening socket. 990 */ 991 if (inp->inp_flags & INP_TIMEWAIT) { 992 tcp_dooptions(&to, optp, optlen, 993 (thflags & TH_SYN) ? TO_SYN : 0); 994 /* 995 * NB: tcp_twcheck unlocks the INP and frees the mbuf. 996 */ 997 if (tcp_twcheck(inp, &to, th, m, tlen)) 998 goto findpcb; 999 return (IPPROTO_DONE); 1000 } 1001 /* 1002 * The TCPCB may no longer exist if the connection is winding 1003 * down or it is in the CLOSED state. Either way we drop the 1004 * segment and send an appropriate response. 1005 */ 1006 tp = intotcpcb(inp); 1007 if (tp == NULL || tp->t_state == TCPS_CLOSED) { 1008 rstreason = BANDLIM_RST_CLOSEDPORT; 1009 goto dropwithreset; 1010 } 1011 1012 if ((tp->t_port != port) && (tp->t_state > TCPS_LISTEN)) { 1013 rstreason = BANDLIM_RST_CLOSEDPORT; 1014 goto dropwithreset; 1015 } 1016 1017 #ifdef TCP_OFFLOAD 1018 if (tp->t_flags & TF_TOE) { 1019 tcp_offload_input(tp, m); 1020 m = NULL; /* consumed by the TOE driver */ 1021 goto dropunlock; 1022 } 1023 #endif 1024 1025 #ifdef MAC 1026 if (mac_inpcb_check_deliver(inp, m)) 1027 goto dropunlock; 1028 #endif 1029 so = inp->inp_socket; 1030 KASSERT(so != NULL, ("%s: so == NULL", __func__)); 1031 #ifdef TCPDEBUG 1032 if (so->so_options & SO_DEBUG) { 1033 ostate = tp->t_state; 1034 #ifdef INET6 1035 if (isipv6) { 1036 bcopy((char *)ip6, (char *)tcp_saveipgen, sizeof(*ip6)); 1037 } else 1038 #endif 1039 bcopy((char *)ip, (char *)tcp_saveipgen, sizeof(*ip)); 1040 tcp_savetcp = *th; 1041 } 1042 #endif /* TCPDEBUG */ 1043 /* 1044 * When the socket is accepting connections (the INPCB is in LISTEN 1045 * state) we look into the SYN cache if this is a new connection 1046 * attempt or the completion of a previous one. 1047 */ 1048 KASSERT(tp->t_state == TCPS_LISTEN || !SOLISTENING(so), 1049 ("%s: so accepting but tp %p not listening", __func__, tp)); 1050 if (tp->t_state == TCPS_LISTEN && SOLISTENING(so)) { 1051 struct in_conninfo inc; 1052 1053 bzero(&inc, sizeof(inc)); 1054 #ifdef INET6 1055 if (isipv6) { 1056 inc.inc_flags |= INC_ISIPV6; 1057 if (inp->inp_inc.inc_flags & INC_IPV6MINMTU) 1058 inc.inc_flags |= INC_IPV6MINMTU; 1059 inc.inc6_faddr = ip6->ip6_src; 1060 inc.inc6_laddr = ip6->ip6_dst; 1061 } else 1062 #endif 1063 { 1064 inc.inc_faddr = ip->ip_src; 1065 inc.inc_laddr = ip->ip_dst; 1066 } 1067 inc.inc_fport = th->th_sport; 1068 inc.inc_lport = th->th_dport; 1069 inc.inc_fibnum = so->so_fibnum; 1070 1071 /* 1072 * Check for an existing connection attempt in syncache if 1073 * the flag is only ACK. A successful lookup creates a new 1074 * socket appended to the listen queue in SYN_RECEIVED state. 1075 */ 1076 if ((thflags & (TH_RST|TH_ACK|TH_SYN)) == TH_ACK) { 1077 /* 1078 * Parse the TCP options here because 1079 * syncookies need access to the reflected 1080 * timestamp. 1081 */ 1082 tcp_dooptions(&to, optp, optlen, 0); 1083 /* 1084 * NB: syncache_expand() doesn't unlock 1085 * inp and tcpinfo locks. 1086 */ 1087 rstreason = syncache_expand(&inc, &to, th, &so, m, port); 1088 if (rstreason < 0) { 1089 /* 1090 * A failing TCP MD5 signature comparison 1091 * must result in the segment being dropped 1092 * and must not produce any response back 1093 * to the sender. 1094 */ 1095 goto dropunlock; 1096 } else if (rstreason == 0) { 1097 /* 1098 * No syncache entry or ACK was not 1099 * for our SYN/ACK. Send a RST. 1100 * NB: syncache did its own logging 1101 * of the failure cause. 1102 */ 1103 rstreason = BANDLIM_RST_OPENPORT; 1104 goto dropwithreset; 1105 } 1106 tfo_socket_result: 1107 if (so == NULL) { 1108 /* 1109 * We completed the 3-way handshake 1110 * but could not allocate a socket 1111 * either due to memory shortage, 1112 * listen queue length limits or 1113 * global socket limits. Send RST 1114 * or wait and have the remote end 1115 * retransmit the ACK for another 1116 * try. 1117 */ 1118 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1119 log(LOG_DEBUG, "%s; %s: Listen socket: " 1120 "Socket allocation failed due to " 1121 "limits or memory shortage, %s\n", 1122 s, __func__, 1123 V_tcp_sc_rst_sock_fail ? 1124 "sending RST" : "try again"); 1125 if (V_tcp_sc_rst_sock_fail) { 1126 rstreason = BANDLIM_UNLIMITED; 1127 goto dropwithreset; 1128 } else 1129 goto dropunlock; 1130 } 1131 /* 1132 * Socket is created in state SYN_RECEIVED. 1133 * Unlock the listen socket, lock the newly 1134 * created socket and update the tp variable. 1135 * If we came here via jump to tfo_socket_result, 1136 * then listening socket is read-locked. 1137 */ 1138 INP_UNLOCK(inp); /* listen socket */ 1139 inp = sotoinpcb(so); 1140 /* 1141 * New connection inpcb is already locked by 1142 * syncache_expand(). 1143 */ 1144 INP_WLOCK_ASSERT(inp); 1145 tp = intotcpcb(inp); 1146 KASSERT(tp->t_state == TCPS_SYN_RECEIVED, 1147 ("%s: ", __func__)); 1148 /* 1149 * Process the segment and the data it 1150 * contains. tcp_do_segment() consumes 1151 * the mbuf chain and unlocks the inpcb. 1152 */ 1153 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1154 tp->t_fb->tfb_tcp_do_segment(m, th, so, tp, drop_hdrlen, tlen, 1155 iptos); 1156 return (IPPROTO_DONE); 1157 } 1158 /* 1159 * Segment flag validation for new connection attempts: 1160 * 1161 * Our (SYN|ACK) response was rejected. 1162 * Check with syncache and remove entry to prevent 1163 * retransmits. 1164 * 1165 * NB: syncache_chkrst does its own logging of failure 1166 * causes. 1167 */ 1168 if (thflags & TH_RST) { 1169 syncache_chkrst(&inc, th, m, port); 1170 goto dropunlock; 1171 } 1172 /* 1173 * We can't do anything without SYN. 1174 */ 1175 if ((thflags & TH_SYN) == 0) { 1176 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1177 log(LOG_DEBUG, "%s; %s: Listen socket: " 1178 "SYN is missing, segment ignored\n", 1179 s, __func__); 1180 TCPSTAT_INC(tcps_badsyn); 1181 goto dropunlock; 1182 } 1183 /* 1184 * (SYN|ACK) is bogus on a listen socket. 1185 */ 1186 if (thflags & TH_ACK) { 1187 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1188 log(LOG_DEBUG, "%s; %s: Listen socket: " 1189 "SYN|ACK invalid, segment rejected\n", 1190 s, __func__); 1191 syncache_badack(&inc, port); /* XXX: Not needed! */ 1192 TCPSTAT_INC(tcps_badsyn); 1193 rstreason = BANDLIM_RST_OPENPORT; 1194 goto dropwithreset; 1195 } 1196 /* 1197 * If the drop_synfin option is enabled, drop all 1198 * segments with both the SYN and FIN bits set. 1199 * This prevents e.g. nmap from identifying the 1200 * TCP/IP stack. 1201 * XXX: Poor reasoning. nmap has other methods 1202 * and is constantly refining its stack detection 1203 * strategies. 1204 * XXX: This is a violation of the TCP specification 1205 * and was used by RFC1644. 1206 */ 1207 if ((thflags & TH_FIN) && V_drop_synfin) { 1208 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1209 log(LOG_DEBUG, "%s; %s: Listen socket: " 1210 "SYN|FIN segment ignored (based on " 1211 "sysctl setting)\n", s, __func__); 1212 TCPSTAT_INC(tcps_badsyn); 1213 goto dropunlock; 1214 } 1215 /* 1216 * Segment's flags are (SYN) or (SYN|FIN). 1217 * 1218 * TH_PUSH, TH_URG, TH_ECE, TH_CWR are ignored 1219 * as they do not affect the state of the TCP FSM. 1220 * The data pointed to by TH_URG and th_urp is ignored. 1221 */ 1222 KASSERT((thflags & (TH_RST|TH_ACK)) == 0, 1223 ("%s: Listen socket: TH_RST or TH_ACK set", __func__)); 1224 KASSERT(thflags & (TH_SYN), 1225 ("%s: Listen socket: TH_SYN not set", __func__)); 1226 INP_RLOCK_ASSERT(inp); 1227 #ifdef INET6 1228 /* 1229 * If deprecated address is forbidden, 1230 * we do not accept SYN to deprecated interface 1231 * address to prevent any new inbound connection from 1232 * getting established. 1233 * When we do not accept SYN, we send a TCP RST, 1234 * with deprecated source address (instead of dropping 1235 * it). We compromise it as it is much better for peer 1236 * to send a RST, and RST will be the final packet 1237 * for the exchange. 1238 * 1239 * If we do not forbid deprecated addresses, we accept 1240 * the SYN packet. RFC2462 does not suggest dropping 1241 * SYN in this case. 1242 * If we decipher RFC2462 5.5.4, it says like this: 1243 * 1. use of deprecated addr with existing 1244 * communication is okay - "SHOULD continue to be 1245 * used" 1246 * 2. use of it with new communication: 1247 * (2a) "SHOULD NOT be used if alternate address 1248 * with sufficient scope is available" 1249 * (2b) nothing mentioned otherwise. 1250 * Here we fall into (2b) case as we have no choice in 1251 * our source address selection - we must obey the peer. 1252 * 1253 * The wording in RFC2462 is confusing, and there are 1254 * multiple description text for deprecated address 1255 * handling - worse, they are not exactly the same. 1256 * I believe 5.5.4 is the best one, so we follow 5.5.4. 1257 */ 1258 if (isipv6 && !V_ip6_use_deprecated) { 1259 struct in6_ifaddr *ia6; 1260 1261 ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */, false); 1262 if (ia6 != NULL && 1263 (ia6->ia6_flags & IN6_IFF_DEPRECATED)) { 1264 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1265 log(LOG_DEBUG, "%s; %s: Listen socket: " 1266 "Connection attempt to deprecated " 1267 "IPv6 address rejected\n", 1268 s, __func__); 1269 rstreason = BANDLIM_RST_OPENPORT; 1270 goto dropwithreset; 1271 } 1272 } 1273 #endif /* INET6 */ 1274 /* 1275 * Basic sanity checks on incoming SYN requests: 1276 * Don't respond if the destination is a link layer 1277 * broadcast according to RFC1122 4.2.3.10, p. 104. 1278 * If it is from this socket it must be forged. 1279 * Don't respond if the source or destination is a 1280 * global or subnet broad- or multicast address. 1281 * Note that it is quite possible to receive unicast 1282 * link-layer packets with a broadcast IP address. Use 1283 * in_broadcast() to find them. 1284 */ 1285 if (m->m_flags & (M_BCAST|M_MCAST)) { 1286 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1287 log(LOG_DEBUG, "%s; %s: Listen socket: " 1288 "Connection attempt from broad- or multicast " 1289 "link layer address ignored\n", s, __func__); 1290 goto dropunlock; 1291 } 1292 #ifdef INET6 1293 if (isipv6) { 1294 if (th->th_dport == th->th_sport && 1295 IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &ip6->ip6_src)) { 1296 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1297 log(LOG_DEBUG, "%s; %s: Listen socket: " 1298 "Connection attempt to/from self " 1299 "ignored\n", s, __func__); 1300 goto dropunlock; 1301 } 1302 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 1303 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) { 1304 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1305 log(LOG_DEBUG, "%s; %s: Listen socket: " 1306 "Connection attempt from/to multicast " 1307 "address ignored\n", s, __func__); 1308 goto dropunlock; 1309 } 1310 } 1311 #endif 1312 #if defined(INET) && defined(INET6) 1313 else 1314 #endif 1315 #ifdef INET 1316 { 1317 if (th->th_dport == th->th_sport && 1318 ip->ip_dst.s_addr == ip->ip_src.s_addr) { 1319 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1320 log(LOG_DEBUG, "%s; %s: Listen socket: " 1321 "Connection attempt from/to self " 1322 "ignored\n", s, __func__); 1323 goto dropunlock; 1324 } 1325 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || 1326 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 1327 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || 1328 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) { 1329 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1330 log(LOG_DEBUG, "%s; %s: Listen socket: " 1331 "Connection attempt from/to broad- " 1332 "or multicast address ignored\n", 1333 s, __func__); 1334 goto dropunlock; 1335 } 1336 } 1337 #endif 1338 /* 1339 * SYN appears to be valid. Create compressed TCP state 1340 * for syncache. 1341 */ 1342 #ifdef TCPDEBUG 1343 if (so->so_options & SO_DEBUG) 1344 tcp_trace(TA_INPUT, ostate, tp, 1345 (void *)tcp_saveipgen, &tcp_savetcp, 0); 1346 #endif 1347 TCP_PROBE3(debug__input, tp, th, m); 1348 tcp_dooptions(&to, optp, optlen, TO_SYN); 1349 if ((so = syncache_add(&inc, &to, th, inp, so, m, NULL, NULL, 1350 iptos, port)) != NULL) 1351 goto tfo_socket_result; 1352 1353 /* 1354 * Entry added to syncache and mbuf consumed. 1355 * Only the listen socket is unlocked by syncache_add(). 1356 */ 1357 return (IPPROTO_DONE); 1358 } else if (tp->t_state == TCPS_LISTEN) { 1359 /* 1360 * When a listen socket is torn down the SO_ACCEPTCONN 1361 * flag is removed first while connections are drained 1362 * from the accept queue in a unlock/lock cycle of the 1363 * ACCEPT_LOCK, opening a race condition allowing a SYN 1364 * attempt go through unhandled. 1365 */ 1366 goto dropunlock; 1367 } 1368 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 1369 if (tp->t_flags & TF_SIGNATURE) { 1370 tcp_dooptions(&to, optp, optlen, thflags); 1371 if ((to.to_flags & TOF_SIGNATURE) == 0) { 1372 TCPSTAT_INC(tcps_sig_err_nosigopt); 1373 goto dropunlock; 1374 } 1375 if (!TCPMD5_ENABLED() || 1376 TCPMD5_INPUT(m, th, to.to_signature) != 0) 1377 goto dropunlock; 1378 } 1379 #endif 1380 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1381 1382 /* 1383 * Segment belongs to a connection in SYN_SENT, ESTABLISHED or later 1384 * state. tcp_do_segment() always consumes the mbuf chain, unlocks 1385 * the inpcb, and unlocks pcbinfo. 1386 * 1387 * XXXGL: in case of a pure SYN arriving on existing connection 1388 * TCP stacks won't need to modify the PCB, they would either drop 1389 * the segment silently, or send a challenge ACK. However, we try 1390 * to upgrade the lock, because calling convention for stacks is 1391 * write-lock on PCB. If upgrade fails, drop the SYN. 1392 */ 1393 if (lookupflag == INPLOOKUP_RLOCKPCB && INP_TRY_UPGRADE(inp) == 0) 1394 goto dropunlock; 1395 1396 tp->t_fb->tfb_tcp_do_segment(m, th, so, tp, drop_hdrlen, tlen, iptos); 1397 return (IPPROTO_DONE); 1398 1399 dropwithreset: 1400 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1401 1402 if (inp != NULL) { 1403 tcp_dropwithreset(m, th, tp, tlen, rstreason); 1404 INP_UNLOCK(inp); 1405 } else 1406 tcp_dropwithreset(m, th, NULL, tlen, rstreason); 1407 m = NULL; /* mbuf chain got consumed. */ 1408 goto drop; 1409 1410 dropunlock: 1411 if (m != NULL) 1412 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1413 1414 if (inp != NULL) 1415 INP_UNLOCK(inp); 1416 1417 drop: 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 (tp == NULL) { 1503 return; 1504 } 1505 if (so == NULL) { 1506 return; 1507 } 1508 INP_LOCK_ASSERT(tp->t_inpcb); 1509 if (tp->t_flags & TF_WAKESOR) { 1510 tp->t_flags &= ~TF_WAKESOR; 1511 SOCKBUF_LOCK_ASSERT(&so->so_rcv); 1512 sorwakeup_locked(so); 1513 } 1514 } 1515 1516 void 1517 tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so, 1518 struct tcpcb *tp, int drop_hdrlen, int tlen, uint8_t iptos) 1519 { 1520 int thflags, acked, ourfinisacked, needoutput = 0, sack_changed; 1521 int rstreason, todrop, win, incforsyn = 0; 1522 uint32_t tiwin; 1523 uint16_t nsegs; 1524 char *s; 1525 struct in_conninfo *inc; 1526 struct mbuf *mfree; 1527 struct tcpopt to; 1528 int tfo_syn; 1529 u_int maxseg; 1530 1531 #ifdef TCPDEBUG 1532 /* 1533 * The size of tcp_saveipgen must be the size of the max ip header, 1534 * now IPv6. 1535 */ 1536 u_char tcp_saveipgen[IP6_HDR_LEN]; 1537 struct tcphdr tcp_savetcp; 1538 short ostate = 0; 1539 #endif 1540 thflags = th->th_flags; 1541 inc = &tp->t_inpcb->inp_inc; 1542 tp->sackhint.last_sack_ack = 0; 1543 sack_changed = 0; 1544 nsegs = max(1, m->m_pkthdr.lro_nsegs); 1545 1546 NET_EPOCH_ASSERT(); 1547 INP_WLOCK_ASSERT(tp->t_inpcb); 1548 KASSERT(tp->t_state > TCPS_LISTEN, ("%s: TCPS_LISTEN", 1549 __func__)); 1550 KASSERT(tp->t_state != TCPS_TIME_WAIT, ("%s: TCPS_TIME_WAIT", 1551 __func__)); 1552 1553 #ifdef TCPPCAP 1554 /* Save segment, if requested. */ 1555 tcp_pcap_add(th, m, &(tp->t_inpkts)); 1556 #endif 1557 TCP_LOG_EVENT(tp, th, &so->so_rcv, &so->so_snd, TCP_LOG_IN, 0, 1558 tlen, NULL, true); 1559 1560 if ((thflags & TH_SYN) && (thflags & TH_FIN) && V_drop_synfin) { 1561 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1562 log(LOG_DEBUG, "%s; %s: " 1563 "SYN|FIN segment ignored (based on " 1564 "sysctl setting)\n", s, __func__); 1565 free(s, M_TCPLOG); 1566 } 1567 goto drop; 1568 } 1569 1570 /* 1571 * If a segment with the ACK-bit set arrives in the SYN-SENT state 1572 * check SEQ.ACK first. 1573 */ 1574 if ((tp->t_state == TCPS_SYN_SENT) && (thflags & TH_ACK) && 1575 (SEQ_LEQ(th->th_ack, tp->iss) || SEQ_GT(th->th_ack, tp->snd_max))) { 1576 rstreason = BANDLIM_UNLIMITED; 1577 goto dropwithreset; 1578 } 1579 1580 /* 1581 * Segment received on connection. 1582 * Reset idle time and keep-alive timer. 1583 * XXX: This should be done after segment 1584 * validation to ignore broken/spoofed segs. 1585 */ 1586 tp->t_rcvtime = ticks; 1587 1588 /* 1589 * Scale up the window into a 32-bit value. 1590 * For the SYN_SENT state the scale is zero. 1591 */ 1592 tiwin = th->th_win << tp->snd_scale; 1593 #ifdef STATS 1594 stats_voi_update_abs_ulong(tp->t_stats, VOI_TCP_FRWIN, tiwin); 1595 #endif 1596 1597 /* 1598 * TCP ECN processing. 1599 */ 1600 if (tp->t_flags2 & TF2_ECN_PERMIT) { 1601 if (thflags & TH_CWR) { 1602 tp->t_flags2 &= ~TF2_ECN_SND_ECE; 1603 tp->t_flags |= TF_ACKNOW; 1604 } 1605 switch (iptos & IPTOS_ECN_MASK) { 1606 case IPTOS_ECN_CE: 1607 tp->t_flags2 |= TF2_ECN_SND_ECE; 1608 TCPSTAT_INC(tcps_ecn_ce); 1609 break; 1610 case IPTOS_ECN_ECT0: 1611 TCPSTAT_INC(tcps_ecn_ect0); 1612 break; 1613 case IPTOS_ECN_ECT1: 1614 TCPSTAT_INC(tcps_ecn_ect1); 1615 break; 1616 } 1617 1618 /* Process a packet differently from RFC3168. */ 1619 cc_ecnpkt_handler(tp, th, iptos); 1620 1621 /* Congestion experienced. */ 1622 if (thflags & TH_ECE) { 1623 cc_cong_signal(tp, th, CC_ECN); 1624 } 1625 } 1626 1627 /* 1628 * Parse options on any incoming segment. 1629 */ 1630 tcp_dooptions(&to, (u_char *)(th + 1), 1631 (th->th_off << 2) - sizeof(struct tcphdr), 1632 (thflags & TH_SYN) ? TO_SYN : 0); 1633 1634 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 1635 if ((tp->t_flags & TF_SIGNATURE) != 0 && 1636 (to.to_flags & TOF_SIGNATURE) == 0) { 1637 TCPSTAT_INC(tcps_sig_err_sigopt); 1638 /* XXX: should drop? */ 1639 } 1640 #endif 1641 /* 1642 * If echoed timestamp is later than the current time, 1643 * fall back to non RFC1323 RTT calculation. Normalize 1644 * timestamp if syncookies were used when this connection 1645 * was established. 1646 */ 1647 if ((to.to_flags & TOF_TS) && (to.to_tsecr != 0)) { 1648 to.to_tsecr -= tp->ts_offset; 1649 if (TSTMP_GT(to.to_tsecr, tcp_ts_getticks())) 1650 to.to_tsecr = 0; 1651 else if (tp->t_flags & TF_PREVVALID && 1652 tp->t_badrxtwin != 0 && SEQ_LT(to.to_tsecr, tp->t_badrxtwin)) 1653 cc_cong_signal(tp, th, CC_RTO_ERR); 1654 } 1655 /* 1656 * Process options only when we get SYN/ACK back. The SYN case 1657 * for incoming connections is handled in tcp_syncache. 1658 * According to RFC1323 the window field in a SYN (i.e., a <SYN> 1659 * or <SYN,ACK>) segment itself is never scaled. 1660 * XXX this is traditional behavior, may need to be cleaned up. 1661 */ 1662 if (tp->t_state == TCPS_SYN_SENT && (thflags & TH_SYN)) { 1663 /* Handle parallel SYN for ECN */ 1664 if (!(thflags & TH_ACK) && 1665 ((thflags & (TH_CWR | TH_ECE)) == (TH_CWR | TH_ECE)) && 1666 ((V_tcp_do_ecn == 1) || (V_tcp_do_ecn == 2))) { 1667 tp->t_flags2 |= TF2_ECN_PERMIT; 1668 tp->t_flags2 |= TF2_ECN_SND_ECE; 1669 TCPSTAT_INC(tcps_ecn_shs); 1670 } 1671 if ((to.to_flags & TOF_SCALE) && 1672 (tp->t_flags & TF_REQ_SCALE) && 1673 !(tp->t_flags & TF_NOOPT)) { 1674 tp->t_flags |= TF_RCVD_SCALE; 1675 tp->snd_scale = to.to_wscale; 1676 } else 1677 tp->t_flags &= ~TF_REQ_SCALE; 1678 /* 1679 * Initial send window. It will be updated with 1680 * the next incoming segment to the scaled value. 1681 */ 1682 tp->snd_wnd = th->th_win; 1683 if ((to.to_flags & TOF_TS) && 1684 (tp->t_flags & TF_REQ_TSTMP) && 1685 !(tp->t_flags & TF_NOOPT)) { 1686 tp->t_flags |= TF_RCVD_TSTMP; 1687 tp->ts_recent = to.to_tsval; 1688 tp->ts_recent_age = tcp_ts_getticks(); 1689 } else 1690 tp->t_flags &= ~TF_REQ_TSTMP; 1691 if (to.to_flags & TOF_MSS) 1692 tcp_mss(tp, to.to_mss); 1693 if ((tp->t_flags & TF_SACK_PERMIT) && 1694 (!(to.to_flags & TOF_SACKPERM) || 1695 (tp->t_flags & TF_NOOPT))) 1696 tp->t_flags &= ~TF_SACK_PERMIT; 1697 if (IS_FASTOPEN(tp->t_flags)) { 1698 if ((to.to_flags & TOF_FASTOPEN) && 1699 !(tp->t_flags & TF_NOOPT)) { 1700 uint16_t mss; 1701 1702 if (to.to_flags & TOF_MSS) 1703 mss = to.to_mss; 1704 else 1705 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) 1706 mss = TCP6_MSS; 1707 else 1708 mss = TCP_MSS; 1709 tcp_fastopen_update_cache(tp, mss, 1710 to.to_tfo_len, to.to_tfo_cookie); 1711 } else 1712 tcp_fastopen_disable_path(tp); 1713 } 1714 } 1715 1716 /* 1717 * If timestamps were negotiated during SYN/ACK and a 1718 * segment without a timestamp is received, silently drop 1719 * the segment, unless it is a RST segment or missing timestamps are 1720 * tolerated. 1721 * See section 3.2 of RFC 7323. 1722 */ 1723 if ((tp->t_flags & TF_RCVD_TSTMP) && !(to.to_flags & TOF_TS)) { 1724 if (((thflags & TH_RST) != 0) || V_tcp_tolerate_missing_ts) { 1725 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1726 log(LOG_DEBUG, "%s; %s: Timestamp missing, " 1727 "segment processed normally\n", 1728 s, __func__); 1729 free(s, M_TCPLOG); 1730 } 1731 } else { 1732 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1733 log(LOG_DEBUG, "%s; %s: Timestamp missing, " 1734 "segment silently dropped\n", s, __func__); 1735 free(s, M_TCPLOG); 1736 } 1737 goto drop; 1738 } 1739 } 1740 /* 1741 * If timestamps were not negotiated during SYN/ACK and a 1742 * segment with a timestamp is received, ignore the 1743 * timestamp and process the packet normally. 1744 * See section 3.2 of RFC 7323. 1745 */ 1746 if (!(tp->t_flags & TF_RCVD_TSTMP) && (to.to_flags & TOF_TS)) { 1747 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1748 log(LOG_DEBUG, "%s; %s: Timestamp not expected, " 1749 "segment processed normally\n", s, __func__); 1750 free(s, M_TCPLOG); 1751 } 1752 } 1753 1754 /* 1755 * Header prediction: check for the two common cases 1756 * of a uni-directional data xfer. If the packet has 1757 * no control flags, is in-sequence, the window didn't 1758 * change and we're not retransmitting, it's a 1759 * candidate. If the length is zero and the ack moved 1760 * forward, we're the sender side of the xfer. Just 1761 * free the data acked & wake any higher level process 1762 * that was blocked waiting for space. If the length 1763 * is non-zero and the ack didn't move, we're the 1764 * receiver side. If we're getting packets in-order 1765 * (the reassembly queue is empty), add the data to 1766 * the socket buffer and note that we need a delayed ack. 1767 * Make sure that the hidden state-flags are also off. 1768 * Since we check for TCPS_ESTABLISHED first, it can only 1769 * be TH_NEEDSYN. 1770 */ 1771 if (tp->t_state == TCPS_ESTABLISHED && 1772 th->th_seq == tp->rcv_nxt && 1773 (thflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK && 1774 tp->snd_nxt == tp->snd_max && 1775 tiwin && tiwin == tp->snd_wnd && 1776 ((tp->t_flags & (TF_NEEDSYN|TF_NEEDFIN)) == 0) && 1777 SEGQ_EMPTY(tp) && 1778 ((to.to_flags & TOF_TS) == 0 || 1779 TSTMP_GEQ(to.to_tsval, tp->ts_recent)) ) { 1780 /* 1781 * If last ACK falls within this segment's sequence numbers, 1782 * record the timestamp. 1783 * NOTE that the test is modified according to the latest 1784 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 1785 */ 1786 if ((to.to_flags & TOF_TS) != 0 && 1787 SEQ_LEQ(th->th_seq, tp->last_ack_sent)) { 1788 tp->ts_recent_age = tcp_ts_getticks(); 1789 tp->ts_recent = to.to_tsval; 1790 } 1791 1792 if (tlen == 0) { 1793 if (SEQ_GT(th->th_ack, tp->snd_una) && 1794 SEQ_LEQ(th->th_ack, tp->snd_max) && 1795 !IN_RECOVERY(tp->t_flags) && 1796 (to.to_flags & TOF_SACK) == 0 && 1797 TAILQ_EMPTY(&tp->snd_holes)) { 1798 /* 1799 * This is a pure ack for outstanding data. 1800 */ 1801 TCPSTAT_INC(tcps_predack); 1802 1803 /* 1804 * "bad retransmit" recovery without timestamps. 1805 */ 1806 if ((to.to_flags & TOF_TS) == 0 && 1807 tp->t_rxtshift == 1 && 1808 tp->t_flags & TF_PREVVALID && 1809 (int)(ticks - tp->t_badrxtwin) < 0) { 1810 cc_cong_signal(tp, th, CC_RTO_ERR); 1811 } 1812 1813 /* 1814 * Recalculate the transmit timer / rtt. 1815 * 1816 * Some boxes send broken timestamp replies 1817 * during the SYN+ACK phase, ignore 1818 * timestamps of 0 or we could calculate a 1819 * huge RTT and blow up the retransmit timer. 1820 */ 1821 if ((to.to_flags & TOF_TS) != 0 && 1822 to.to_tsecr) { 1823 uint32_t t; 1824 1825 t = tcp_ts_getticks() - to.to_tsecr; 1826 if (!tp->t_rttlow || tp->t_rttlow > t) 1827 tp->t_rttlow = t; 1828 tcp_xmit_timer(tp, 1829 TCP_TS_TO_TICKS(t) + 1); 1830 } else if (tp->t_rtttime && 1831 SEQ_GT(th->th_ack, tp->t_rtseq)) { 1832 if (!tp->t_rttlow || 1833 tp->t_rttlow > ticks - tp->t_rtttime) 1834 tp->t_rttlow = ticks - tp->t_rtttime; 1835 tcp_xmit_timer(tp, 1836 ticks - tp->t_rtttime); 1837 } 1838 acked = BYTES_THIS_ACK(tp, th); 1839 1840 #ifdef TCP_HHOOK 1841 /* Run HHOOK_TCP_ESTABLISHED_IN helper hooks. */ 1842 hhook_run_tcp_est_in(tp, th, &to); 1843 #endif 1844 1845 TCPSTAT_ADD(tcps_rcvackpack, nsegs); 1846 TCPSTAT_ADD(tcps_rcvackbyte, acked); 1847 sbdrop(&so->so_snd, acked); 1848 if (SEQ_GT(tp->snd_una, tp->snd_recover) && 1849 SEQ_LEQ(th->th_ack, tp->snd_recover)) 1850 tp->snd_recover = th->th_ack - 1; 1851 1852 /* 1853 * Let the congestion control algorithm update 1854 * congestion control related information. This 1855 * typically means increasing the congestion 1856 * window. 1857 */ 1858 cc_ack_received(tp, th, nsegs, CC_ACK); 1859 1860 tp->snd_una = th->th_ack; 1861 /* 1862 * Pull snd_wl2 up to prevent seq wrap relative 1863 * to th_ack. 1864 */ 1865 tp->snd_wl2 = th->th_ack; 1866 tp->t_dupacks = 0; 1867 m_freem(m); 1868 1869 /* 1870 * If all outstanding data are acked, stop 1871 * retransmit timer, otherwise restart timer 1872 * using current (possibly backed-off) value. 1873 * If process is waiting for space, 1874 * wakeup/selwakeup/signal. If data 1875 * are ready to send, let tcp_output 1876 * decide between more output or persist. 1877 */ 1878 #ifdef TCPDEBUG 1879 if (so->so_options & SO_DEBUG) 1880 tcp_trace(TA_INPUT, ostate, tp, 1881 (void *)tcp_saveipgen, 1882 &tcp_savetcp, 0); 1883 #endif 1884 TCP_PROBE3(debug__input, tp, th, m); 1885 if (tp->snd_una == tp->snd_max) 1886 tcp_timer_activate(tp, TT_REXMT, 0); 1887 else if (!tcp_timer_active(tp, TT_PERSIST)) 1888 tcp_timer_activate(tp, TT_REXMT, 1889 tp->t_rxtcur); 1890 sowwakeup(so); 1891 if (sbavail(&so->so_snd)) 1892 (void) tcp_output(tp); 1893 goto check_delack; 1894 } 1895 } else if (th->th_ack == tp->snd_una && 1896 tlen <= sbspace(&so->so_rcv)) { 1897 int newsize = 0; /* automatic sockbuf scaling */ 1898 1899 /* 1900 * This is a pure, in-sequence data packet with 1901 * nothing on the reassembly queue and we have enough 1902 * buffer space to take it. 1903 */ 1904 /* Clean receiver SACK report if present */ 1905 if ((tp->t_flags & TF_SACK_PERMIT) && tp->rcv_numsacks) 1906 tcp_clean_sackreport(tp); 1907 TCPSTAT_INC(tcps_preddat); 1908 tp->rcv_nxt += tlen; 1909 if (tlen && 1910 ((tp->t_flags2 & TF2_FBYTES_COMPLETE) == 0) && 1911 (tp->t_fbyte_in == 0)) { 1912 tp->t_fbyte_in = ticks; 1913 if (tp->t_fbyte_in == 0) 1914 tp->t_fbyte_in = 1; 1915 if (tp->t_fbyte_out && tp->t_fbyte_in) 1916 tp->t_flags2 |= TF2_FBYTES_COMPLETE; 1917 } 1918 /* 1919 * Pull snd_wl1 up to prevent seq wrap relative to 1920 * th_seq. 1921 */ 1922 tp->snd_wl1 = th->th_seq; 1923 /* 1924 * Pull rcv_up up to prevent seq wrap relative to 1925 * rcv_nxt. 1926 */ 1927 tp->rcv_up = tp->rcv_nxt; 1928 TCPSTAT_ADD(tcps_rcvpack, nsegs); 1929 TCPSTAT_ADD(tcps_rcvbyte, tlen); 1930 #ifdef TCPDEBUG 1931 if (so->so_options & SO_DEBUG) 1932 tcp_trace(TA_INPUT, ostate, tp, 1933 (void *)tcp_saveipgen, &tcp_savetcp, 0); 1934 #endif 1935 TCP_PROBE3(debug__input, tp, th, m); 1936 1937 newsize = tcp_autorcvbuf(m, th, so, tp, tlen); 1938 1939 /* Add data to socket buffer. */ 1940 SOCKBUF_LOCK(&so->so_rcv); 1941 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 1942 m_freem(m); 1943 } else { 1944 /* 1945 * Set new socket buffer size. 1946 * Give up when limit is reached. 1947 */ 1948 if (newsize) 1949 if (!sbreserve_locked(&so->so_rcv, 1950 newsize, so, NULL)) 1951 so->so_rcv.sb_flags &= ~SB_AUTOSIZE; 1952 m_adj(m, drop_hdrlen); /* delayed header drop */ 1953 sbappendstream_locked(&so->so_rcv, m, 0); 1954 } 1955 /* NB: sorwakeup_locked() does an implicit unlock. */ 1956 sorwakeup_locked(so); 1957 if (DELAY_ACK(tp, tlen)) { 1958 tp->t_flags |= TF_DELACK; 1959 } else { 1960 tp->t_flags |= TF_ACKNOW; 1961 tcp_output(tp); 1962 } 1963 goto check_delack; 1964 } 1965 } 1966 1967 /* 1968 * Calculate amount of space in receive window, 1969 * and then do TCP input processing. 1970 * Receive window is amount of space in rcv queue, 1971 * but not less than advertised window. 1972 */ 1973 win = sbspace(&so->so_rcv); 1974 if (win < 0) 1975 win = 0; 1976 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 1977 1978 switch (tp->t_state) { 1979 /* 1980 * If the state is SYN_RECEIVED: 1981 * if seg contains an ACK, but not for our SYN/ACK, send a RST. 1982 */ 1983 case TCPS_SYN_RECEIVED: 1984 if ((thflags & TH_ACK) && 1985 (SEQ_LEQ(th->th_ack, tp->snd_una) || 1986 SEQ_GT(th->th_ack, tp->snd_max))) { 1987 rstreason = BANDLIM_RST_OPENPORT; 1988 goto dropwithreset; 1989 } 1990 if (IS_FASTOPEN(tp->t_flags)) { 1991 /* 1992 * When a TFO connection is in SYN_RECEIVED, the 1993 * only valid packets are the initial SYN, a 1994 * retransmit/copy of the initial SYN (possibly with 1995 * a subset of the original data), a valid ACK, a 1996 * FIN, or a RST. 1997 */ 1998 if ((thflags & (TH_SYN|TH_ACK)) == (TH_SYN|TH_ACK)) { 1999 rstreason = BANDLIM_RST_OPENPORT; 2000 goto dropwithreset; 2001 } else if (thflags & TH_SYN) { 2002 /* non-initial SYN is ignored */ 2003 if ((tcp_timer_active(tp, TT_DELACK) || 2004 tcp_timer_active(tp, TT_REXMT))) 2005 goto drop; 2006 } else if (!(thflags & (TH_ACK|TH_FIN|TH_RST))) { 2007 goto drop; 2008 } 2009 } 2010 break; 2011 2012 /* 2013 * If the state is SYN_SENT: 2014 * if seg contains a RST with valid ACK (SEQ.ACK has already 2015 * been verified), then drop the connection. 2016 * if seg contains a RST without an ACK, drop the seg. 2017 * if seg does not contain SYN, then drop the seg. 2018 * Otherwise this is an acceptable SYN segment 2019 * initialize tp->rcv_nxt and tp->irs 2020 * if seg contains ack then advance tp->snd_una 2021 * if seg contains an ECE and ECN support is enabled, the stream 2022 * is ECN capable. 2023 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 2024 * arrange for segment to be acked (eventually) 2025 * continue processing rest of data/controls, beginning with URG 2026 */ 2027 case TCPS_SYN_SENT: 2028 if ((thflags & (TH_ACK|TH_RST)) == (TH_ACK|TH_RST)) { 2029 TCP_PROBE5(connect__refused, NULL, tp, 2030 m, tp, th); 2031 tp = tcp_drop(tp, ECONNREFUSED); 2032 } 2033 if (thflags & TH_RST) 2034 goto drop; 2035 if (!(thflags & TH_SYN)) 2036 goto drop; 2037 2038 tp->irs = th->th_seq; 2039 tcp_rcvseqinit(tp); 2040 if (thflags & TH_ACK) { 2041 int tfo_partial_ack = 0; 2042 2043 TCPSTAT_INC(tcps_connects); 2044 soisconnected(so); 2045 #ifdef MAC 2046 mac_socketpeer_set_from_mbuf(m, so); 2047 #endif 2048 /* Do window scaling on this connection? */ 2049 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2050 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2051 tp->rcv_scale = tp->request_r_scale; 2052 } 2053 tp->rcv_adv += min(tp->rcv_wnd, 2054 TCP_MAXWIN << tp->rcv_scale); 2055 tp->snd_una++; /* SYN is acked */ 2056 /* 2057 * If not all the data that was sent in the TFO SYN 2058 * has been acked, resend the remainder right away. 2059 */ 2060 if (IS_FASTOPEN(tp->t_flags) && 2061 (tp->snd_una != tp->snd_max)) { 2062 tp->snd_nxt = th->th_ack; 2063 tfo_partial_ack = 1; 2064 } 2065 /* 2066 * If there's data, delay ACK; if there's also a FIN 2067 * ACKNOW will be turned on later. 2068 */ 2069 if (DELAY_ACK(tp, tlen) && tlen != 0 && !tfo_partial_ack) 2070 tcp_timer_activate(tp, TT_DELACK, 2071 tcp_delacktime); 2072 else 2073 tp->t_flags |= TF_ACKNOW; 2074 2075 if (((thflags & (TH_CWR | TH_ECE)) == TH_ECE) && 2076 (V_tcp_do_ecn == 1)) { 2077 tp->t_flags2 |= TF2_ECN_PERMIT; 2078 TCPSTAT_INC(tcps_ecn_shs); 2079 } 2080 2081 /* 2082 * Received <SYN,ACK> in SYN_SENT[*] state. 2083 * Transitions: 2084 * SYN_SENT --> ESTABLISHED 2085 * SYN_SENT* --> FIN_WAIT_1 2086 */ 2087 tp->t_starttime = ticks; 2088 if (tp->t_flags & TF_NEEDFIN) { 2089 tcp_state_change(tp, TCPS_FIN_WAIT_1); 2090 tp->t_flags &= ~TF_NEEDFIN; 2091 thflags &= ~TH_SYN; 2092 } else { 2093 tcp_state_change(tp, TCPS_ESTABLISHED); 2094 TCP_PROBE5(connect__established, NULL, tp, 2095 m, tp, th); 2096 cc_conn_init(tp); 2097 tcp_timer_activate(tp, TT_KEEP, 2098 TP_KEEPIDLE(tp)); 2099 } 2100 } else { 2101 /* 2102 * Received initial SYN in SYN-SENT[*] state => 2103 * simultaneous open. 2104 * If it succeeds, connection is * half-synchronized. 2105 * Otherwise, do 3-way handshake: 2106 * SYN-SENT -> SYN-RECEIVED 2107 * SYN-SENT* -> SYN-RECEIVED* 2108 */ 2109 tp->t_flags |= (TF_ACKNOW | TF_NEEDSYN); 2110 tcp_timer_activate(tp, TT_REXMT, 0); 2111 tcp_state_change(tp, TCPS_SYN_RECEIVED); 2112 } 2113 2114 INP_WLOCK_ASSERT(tp->t_inpcb); 2115 2116 /* 2117 * Advance th->th_seq to correspond to first data byte. 2118 * If data, trim to stay within window, 2119 * dropping FIN if necessary. 2120 */ 2121 th->th_seq++; 2122 if (tlen > tp->rcv_wnd) { 2123 todrop = tlen - tp->rcv_wnd; 2124 m_adj(m, -todrop); 2125 tlen = tp->rcv_wnd; 2126 thflags &= ~TH_FIN; 2127 TCPSTAT_INC(tcps_rcvpackafterwin); 2128 TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); 2129 } 2130 tp->snd_wl1 = th->th_seq - 1; 2131 tp->rcv_up = th->th_seq; 2132 /* 2133 * Client side of transaction: already sent SYN and data. 2134 * If the remote host used T/TCP to validate the SYN, 2135 * our data will be ACK'd; if so, enter normal data segment 2136 * processing in the middle of step 5, ack processing. 2137 * Otherwise, goto step 6. 2138 */ 2139 if (thflags & TH_ACK) 2140 goto process_ACK; 2141 2142 goto step6; 2143 2144 /* 2145 * If the state is LAST_ACK or CLOSING or TIME_WAIT: 2146 * do normal processing. 2147 * 2148 * NB: Leftover from RFC1644 T/TCP. Cases to be reused later. 2149 */ 2150 case TCPS_LAST_ACK: 2151 case TCPS_CLOSING: 2152 break; /* continue normal processing */ 2153 } 2154 2155 /* 2156 * States other than LISTEN or SYN_SENT. 2157 * First check the RST flag and sequence number since reset segments 2158 * are exempt from the timestamp and connection count tests. This 2159 * fixes a bug introduced by the Stevens, vol. 2, p. 960 bugfix 2160 * below which allowed reset segments in half the sequence space 2161 * to fall though and be processed (which gives forged reset 2162 * segments with a random sequence number a 50 percent chance of 2163 * killing a connection). 2164 * Then check timestamp, if present. 2165 * Then check the connection count, if present. 2166 * Then check that at least some bytes of segment are within 2167 * receive window. If segment begins before rcv_nxt, 2168 * drop leading data (and SYN); if nothing left, just ack. 2169 */ 2170 if (thflags & TH_RST) { 2171 /* 2172 * RFC5961 Section 3.2 2173 * 2174 * - RST drops connection only if SEG.SEQ == RCV.NXT. 2175 * - If RST is in window, we send challenge ACK. 2176 * 2177 * Note: to take into account delayed ACKs, we should 2178 * test against last_ack_sent instead of rcv_nxt. 2179 * Note 2: we handle special case of closed window, not 2180 * covered by the RFC. 2181 */ 2182 if ((SEQ_GEQ(th->th_seq, tp->last_ack_sent) && 2183 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) || 2184 (tp->rcv_wnd == 0 && tp->last_ack_sent == th->th_seq)) { 2185 KASSERT(tp->t_state != TCPS_SYN_SENT, 2186 ("%s: TH_RST for TCPS_SYN_SENT th %p tp %p", 2187 __func__, th, tp)); 2188 2189 if (V_tcp_insecure_rst || 2190 tp->last_ack_sent == th->th_seq) { 2191 TCPSTAT_INC(tcps_drops); 2192 /* Drop the connection. */ 2193 switch (tp->t_state) { 2194 case TCPS_SYN_RECEIVED: 2195 so->so_error = ECONNREFUSED; 2196 goto close; 2197 case TCPS_ESTABLISHED: 2198 case TCPS_FIN_WAIT_1: 2199 case TCPS_FIN_WAIT_2: 2200 case TCPS_CLOSE_WAIT: 2201 case TCPS_CLOSING: 2202 case TCPS_LAST_ACK: 2203 so->so_error = ECONNRESET; 2204 close: 2205 /* FALLTHROUGH */ 2206 default: 2207 tp = tcp_close(tp); 2208 } 2209 } else { 2210 TCPSTAT_INC(tcps_badrst); 2211 /* Send challenge ACK. */ 2212 tcp_respond(tp, mtod(m, void *), th, m, 2213 tp->rcv_nxt, tp->snd_nxt, TH_ACK); 2214 tp->last_ack_sent = tp->rcv_nxt; 2215 m = NULL; 2216 } 2217 } 2218 goto drop; 2219 } 2220 2221 /* 2222 * RFC5961 Section 4.2 2223 * Send challenge ACK for any SYN in synchronized state. 2224 */ 2225 if ((thflags & TH_SYN) && tp->t_state != TCPS_SYN_SENT && 2226 tp->t_state != TCPS_SYN_RECEIVED) { 2227 TCPSTAT_INC(tcps_badsyn); 2228 if (V_tcp_insecure_syn && 2229 SEQ_GEQ(th->th_seq, tp->last_ack_sent) && 2230 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) { 2231 tp = tcp_drop(tp, ECONNRESET); 2232 rstreason = BANDLIM_UNLIMITED; 2233 } else { 2234 /* Send challenge ACK. */ 2235 tcp_respond(tp, mtod(m, void *), th, m, tp->rcv_nxt, 2236 tp->snd_nxt, TH_ACK); 2237 tp->last_ack_sent = tp->rcv_nxt; 2238 m = NULL; 2239 } 2240 goto drop; 2241 } 2242 2243 /* 2244 * RFC 1323 PAWS: If we have a timestamp reply on this segment 2245 * and it's less than ts_recent, drop it. 2246 */ 2247 if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent && 2248 TSTMP_LT(to.to_tsval, tp->ts_recent)) { 2249 /* Check to see if ts_recent is over 24 days old. */ 2250 if (tcp_ts_getticks() - tp->ts_recent_age > TCP_PAWS_IDLE) { 2251 /* 2252 * Invalidate ts_recent. If this segment updates 2253 * ts_recent, the age will be reset later and ts_recent 2254 * will get a valid value. If it does not, setting 2255 * ts_recent to zero will at least satisfy the 2256 * requirement that zero be placed in the timestamp 2257 * echo reply when ts_recent isn't valid. The 2258 * age isn't reset until we get a valid ts_recent 2259 * because we don't want out-of-order segments to be 2260 * dropped when ts_recent is old. 2261 */ 2262 tp->ts_recent = 0; 2263 } else { 2264 TCPSTAT_INC(tcps_rcvduppack); 2265 TCPSTAT_ADD(tcps_rcvdupbyte, tlen); 2266 TCPSTAT_INC(tcps_pawsdrop); 2267 if (tlen) 2268 goto dropafterack; 2269 goto drop; 2270 } 2271 } 2272 2273 /* 2274 * In the SYN-RECEIVED state, validate that the packet belongs to 2275 * this connection before trimming the data to fit the receive 2276 * window. Check the sequence number versus IRS since we know 2277 * the sequence numbers haven't wrapped. This is a partial fix 2278 * for the "LAND" DoS attack. 2279 */ 2280 if (tp->t_state == TCPS_SYN_RECEIVED && SEQ_LT(th->th_seq, tp->irs)) { 2281 rstreason = BANDLIM_RST_OPENPORT; 2282 goto dropwithreset; 2283 } 2284 2285 todrop = tp->rcv_nxt - th->th_seq; 2286 if (todrop > 0) { 2287 if (thflags & TH_SYN) { 2288 thflags &= ~TH_SYN; 2289 th->th_seq++; 2290 if (th->th_urp > 1) 2291 th->th_urp--; 2292 else 2293 thflags &= ~TH_URG; 2294 todrop--; 2295 } 2296 /* 2297 * Following if statement from Stevens, vol. 2, p. 960. 2298 */ 2299 if (todrop > tlen 2300 || (todrop == tlen && (thflags & TH_FIN) == 0)) { 2301 /* 2302 * Any valid FIN must be to the left of the window. 2303 * At this point the FIN must be a duplicate or out 2304 * of sequence; drop it. 2305 */ 2306 thflags &= ~TH_FIN; 2307 2308 /* 2309 * Send an ACK to resynchronize and drop any data. 2310 * But keep on processing for RST or ACK. 2311 */ 2312 tp->t_flags |= TF_ACKNOW; 2313 todrop = tlen; 2314 TCPSTAT_INC(tcps_rcvduppack); 2315 TCPSTAT_ADD(tcps_rcvdupbyte, todrop); 2316 } else { 2317 TCPSTAT_INC(tcps_rcvpartduppack); 2318 TCPSTAT_ADD(tcps_rcvpartdupbyte, todrop); 2319 } 2320 /* 2321 * DSACK - add SACK block for dropped range 2322 */ 2323 if ((todrop > 0) && (tp->t_flags & TF_SACK_PERMIT)) { 2324 tcp_update_sack_list(tp, th->th_seq, 2325 th->th_seq + todrop); 2326 /* 2327 * ACK now, as the next in-sequence segment 2328 * will clear the DSACK block again 2329 */ 2330 tp->t_flags |= TF_ACKNOW; 2331 } 2332 drop_hdrlen += todrop; /* drop from the top afterwards */ 2333 th->th_seq += todrop; 2334 tlen -= todrop; 2335 if (th->th_urp > todrop) 2336 th->th_urp -= todrop; 2337 else { 2338 thflags &= ~TH_URG; 2339 th->th_urp = 0; 2340 } 2341 } 2342 2343 /* 2344 * If new data are received on a connection after the 2345 * user processes are gone, then RST the other end. 2346 */ 2347 if ((so->so_state & SS_NOFDREF) && 2348 tp->t_state > TCPS_CLOSE_WAIT && tlen) { 2349 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 2350 log(LOG_DEBUG, "%s; %s: %s: Received %d bytes of data " 2351 "after socket was closed, " 2352 "sending RST and removing tcpcb\n", 2353 s, __func__, tcpstates[tp->t_state], tlen); 2354 free(s, M_TCPLOG); 2355 } 2356 tp = tcp_close(tp); 2357 TCPSTAT_INC(tcps_rcvafterclose); 2358 rstreason = BANDLIM_UNLIMITED; 2359 goto dropwithreset; 2360 } 2361 2362 /* 2363 * If segment ends after window, drop trailing data 2364 * (and PUSH and FIN); if nothing left, just ACK. 2365 */ 2366 todrop = (th->th_seq + tlen) - (tp->rcv_nxt + tp->rcv_wnd); 2367 if (todrop > 0) { 2368 TCPSTAT_INC(tcps_rcvpackafterwin); 2369 if (todrop >= tlen) { 2370 TCPSTAT_ADD(tcps_rcvbyteafterwin, tlen); 2371 /* 2372 * If window is closed can only take segments at 2373 * window edge, and have to drop data and PUSH from 2374 * incoming segments. Continue processing, but 2375 * remember to ack. Otherwise, drop segment 2376 * and ack. 2377 */ 2378 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 2379 tp->t_flags |= TF_ACKNOW; 2380 TCPSTAT_INC(tcps_rcvwinprobe); 2381 } else 2382 goto dropafterack; 2383 } else 2384 TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); 2385 m_adj(m, -todrop); 2386 tlen -= todrop; 2387 thflags &= ~(TH_PUSH|TH_FIN); 2388 } 2389 2390 /* 2391 * If last ACK falls within this segment's sequence numbers, 2392 * record its timestamp. 2393 * NOTE: 2394 * 1) That the test incorporates suggestions from the latest 2395 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 2396 * 2) That updating only on newer timestamps interferes with 2397 * our earlier PAWS tests, so this check should be solely 2398 * predicated on the sequence space of this segment. 2399 * 3) That we modify the segment boundary check to be 2400 * Last.ACK.Sent <= SEG.SEQ + SEG.Len 2401 * instead of RFC1323's 2402 * Last.ACK.Sent < SEG.SEQ + SEG.Len, 2403 * This modified check allows us to overcome RFC1323's 2404 * limitations as described in Stevens TCP/IP Illustrated 2405 * Vol. 2 p.869. In such cases, we can still calculate the 2406 * RTT correctly when RCV.NXT == Last.ACK.Sent. 2407 */ 2408 if ((to.to_flags & TOF_TS) != 0 && 2409 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 2410 SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen + 2411 ((thflags & (TH_SYN|TH_FIN)) != 0))) { 2412 tp->ts_recent_age = tcp_ts_getticks(); 2413 tp->ts_recent = to.to_tsval; 2414 } 2415 2416 /* 2417 * If the ACK bit is off: if in SYN-RECEIVED state or SENDSYN 2418 * flag is on (half-synchronized state), then queue data for 2419 * later processing; else drop segment and return. 2420 */ 2421 if ((thflags & TH_ACK) == 0) { 2422 if (tp->t_state == TCPS_SYN_RECEIVED || 2423 (tp->t_flags & TF_NEEDSYN)) { 2424 if (tp->t_state == TCPS_SYN_RECEIVED && 2425 IS_FASTOPEN(tp->t_flags)) { 2426 tp->snd_wnd = tiwin; 2427 cc_conn_init(tp); 2428 } 2429 goto step6; 2430 } else if (tp->t_flags & TF_ACKNOW) 2431 goto dropafterack; 2432 else 2433 goto drop; 2434 } 2435 2436 /* 2437 * Ack processing. 2438 */ 2439 switch (tp->t_state) { 2440 /* 2441 * In SYN_RECEIVED state, the ack ACKs our SYN, so enter 2442 * ESTABLISHED state and continue processing. 2443 * The ACK was checked above. 2444 */ 2445 case TCPS_SYN_RECEIVED: 2446 2447 TCPSTAT_INC(tcps_connects); 2448 soisconnected(so); 2449 /* Do window scaling? */ 2450 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2451 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2452 tp->rcv_scale = tp->request_r_scale; 2453 } 2454 tp->snd_wnd = tiwin; 2455 /* 2456 * Make transitions: 2457 * SYN-RECEIVED -> ESTABLISHED 2458 * SYN-RECEIVED* -> FIN-WAIT-1 2459 */ 2460 tp->t_starttime = ticks; 2461 if (IS_FASTOPEN(tp->t_flags) && tp->t_tfo_pending) { 2462 tcp_fastopen_decrement_counter(tp->t_tfo_pending); 2463 tp->t_tfo_pending = NULL; 2464 } 2465 if (tp->t_flags & TF_NEEDFIN) { 2466 tcp_state_change(tp, TCPS_FIN_WAIT_1); 2467 tp->t_flags &= ~TF_NEEDFIN; 2468 } else { 2469 tcp_state_change(tp, TCPS_ESTABLISHED); 2470 TCP_PROBE5(accept__established, NULL, tp, 2471 m, tp, th); 2472 /* 2473 * TFO connections call cc_conn_init() during SYN 2474 * processing. Calling it again here for such 2475 * connections is not harmless as it would undo the 2476 * snd_cwnd reduction that occurs when a TFO SYN|ACK 2477 * is retransmitted. 2478 */ 2479 if (!IS_FASTOPEN(tp->t_flags)) 2480 cc_conn_init(tp); 2481 tcp_timer_activate(tp, TT_KEEP, TP_KEEPIDLE(tp)); 2482 } 2483 /* 2484 * Account for the ACK of our SYN prior to 2485 * regular ACK processing below, except for 2486 * simultaneous SYN, which is handled later. 2487 */ 2488 if (SEQ_GT(th->th_ack, tp->snd_una) && !(tp->t_flags & TF_NEEDSYN)) 2489 incforsyn = 1; 2490 /* 2491 * If segment contains data or ACK, will call tcp_reass() 2492 * later; if not, do so now to pass queued data to user. 2493 */ 2494 if (tlen == 0 && (thflags & TH_FIN) == 0) { 2495 (void) tcp_reass(tp, (struct tcphdr *)0, NULL, 0, 2496 (struct mbuf *)0); 2497 tcp_handle_wakeup(tp, so); 2498 } 2499 tp->snd_wl1 = th->th_seq - 1; 2500 /* FALLTHROUGH */ 2501 2502 /* 2503 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 2504 * ACKs. If the ack is in the range 2505 * tp->snd_una < th->th_ack <= tp->snd_max 2506 * then advance tp->snd_una to th->th_ack and drop 2507 * data from the retransmission queue. If this ACK reflects 2508 * more up to date window information we update our window information. 2509 */ 2510 case TCPS_ESTABLISHED: 2511 case TCPS_FIN_WAIT_1: 2512 case TCPS_FIN_WAIT_2: 2513 case TCPS_CLOSE_WAIT: 2514 case TCPS_CLOSING: 2515 case TCPS_LAST_ACK: 2516 if (SEQ_GT(th->th_ack, tp->snd_max)) { 2517 TCPSTAT_INC(tcps_rcvacktoomuch); 2518 goto dropafterack; 2519 } 2520 if ((tp->t_flags & TF_SACK_PERMIT) && 2521 ((to.to_flags & TOF_SACK) || 2522 !TAILQ_EMPTY(&tp->snd_holes))) { 2523 if (((sack_changed = tcp_sack_doack(tp, &to, th->th_ack)) != 0) && 2524 (tp->t_flags & TF_LRD)) { 2525 tcp_sack_lost_retransmission(tp, th); 2526 } 2527 } else 2528 /* 2529 * Reset the value so that previous (valid) value 2530 * from the last ack with SACK doesn't get used. 2531 */ 2532 tp->sackhint.sacked_bytes = 0; 2533 2534 #ifdef TCP_HHOOK 2535 /* Run HHOOK_TCP_ESTABLISHED_IN helper hooks. */ 2536 hhook_run_tcp_est_in(tp, th, &to); 2537 #endif 2538 2539 if (SEQ_LEQ(th->th_ack, tp->snd_una)) { 2540 maxseg = tcp_maxseg(tp); 2541 if (tlen == 0 && 2542 (tiwin == tp->snd_wnd || 2543 (tp->t_flags & TF_SACK_PERMIT))) { 2544 /* 2545 * If this is the first time we've seen a 2546 * FIN from the remote, this is not a 2547 * duplicate and it needs to be processed 2548 * normally. This happens during a 2549 * simultaneous close. 2550 */ 2551 if ((thflags & TH_FIN) && 2552 (TCPS_HAVERCVDFIN(tp->t_state) == 0)) { 2553 tp->t_dupacks = 0; 2554 break; 2555 } 2556 TCPSTAT_INC(tcps_rcvdupack); 2557 /* 2558 * If we have outstanding data (other than 2559 * a window probe), this is a completely 2560 * duplicate ack (ie, window info didn't 2561 * change and FIN isn't set), 2562 * the ack is the biggest we've 2563 * seen and we've seen exactly our rexmt 2564 * threshold of them, assume a packet 2565 * has been dropped and retransmit it. 2566 * Kludge snd_nxt & the congestion 2567 * window so we send only this one 2568 * packet. 2569 * 2570 * We know we're losing at the current 2571 * window size so do congestion avoidance 2572 * (set ssthresh to half the current window 2573 * and pull our congestion window back to 2574 * the new ssthresh). 2575 * 2576 * Dup acks mean that packets have left the 2577 * network (they're now cached at the receiver) 2578 * so bump cwnd by the amount in the receiver 2579 * to keep a constant cwnd packets in the 2580 * network. 2581 * 2582 * When using TCP ECN, notify the peer that 2583 * we reduced the cwnd. 2584 */ 2585 /* 2586 * Following 2 kinds of acks should not affect 2587 * dupack counting: 2588 * 1) Old acks 2589 * 2) Acks with SACK but without any new SACK 2590 * information in them. These could result from 2591 * any anomaly in the network like a switch 2592 * duplicating packets or a possible DoS attack. 2593 */ 2594 if (th->th_ack != tp->snd_una || 2595 ((tp->t_flags & TF_SACK_PERMIT) && 2596 (to.to_flags & TOF_SACK) && 2597 !sack_changed)) 2598 break; 2599 else if (!tcp_timer_active(tp, TT_REXMT)) 2600 tp->t_dupacks = 0; 2601 else if (++tp->t_dupacks > tcprexmtthresh || 2602 IN_FASTRECOVERY(tp->t_flags)) { 2603 cc_ack_received(tp, th, nsegs, 2604 CC_DUPACK); 2605 if (V_tcp_do_prr && 2606 IN_FASTRECOVERY(tp->t_flags)) { 2607 tcp_do_prr_ack(tp, th, &to); 2608 } else if ((tp->t_flags & TF_SACK_PERMIT) && 2609 (to.to_flags & TOF_SACK) && 2610 IN_FASTRECOVERY(tp->t_flags)) { 2611 int awnd; 2612 2613 /* 2614 * Compute the amount of data in flight first. 2615 * We can inject new data into the pipe iff 2616 * we have less than 1/2 the original window's 2617 * worth of data in flight. 2618 */ 2619 if (V_tcp_do_newsack) 2620 awnd = tcp_compute_pipe(tp); 2621 else 2622 awnd = (tp->snd_nxt - tp->snd_fack) + 2623 tp->sackhint.sack_bytes_rexmit; 2624 2625 if (awnd < tp->snd_ssthresh) { 2626 tp->snd_cwnd += maxseg; 2627 if (tp->snd_cwnd > tp->snd_ssthresh) 2628 tp->snd_cwnd = tp->snd_ssthresh; 2629 } 2630 } else 2631 tp->snd_cwnd += maxseg; 2632 (void) tcp_output(tp); 2633 goto drop; 2634 } else if (tp->t_dupacks == tcprexmtthresh || 2635 (tp->t_flags & TF_SACK_PERMIT && 2636 V_tcp_do_newsack && 2637 tp->sackhint.sacked_bytes > 2638 (tcprexmtthresh - 1) * maxseg)) { 2639 enter_recovery: 2640 /* 2641 * Above is the RFC6675 trigger condition of 2642 * more than (dupthresh-1)*maxseg sacked data. 2643 * If the count of holes in the 2644 * scoreboard is >= dupthresh, we could 2645 * also enter loss recovery, but don't 2646 * have that value readily available. 2647 */ 2648 tp->t_dupacks = tcprexmtthresh; 2649 tcp_seq onxt = tp->snd_nxt; 2650 2651 /* 2652 * If we're doing sack, or prr, check 2653 * to see if we're already in sack 2654 * recovery. If we're not doing sack, 2655 * check to see if we're in newreno 2656 * recovery. 2657 */ 2658 if (V_tcp_do_prr || 2659 (tp->t_flags & TF_SACK_PERMIT)) { 2660 if (IN_FASTRECOVERY(tp->t_flags)) { 2661 tp->t_dupacks = 0; 2662 break; 2663 } 2664 } else { 2665 if (SEQ_LEQ(th->th_ack, 2666 tp->snd_recover)) { 2667 tp->t_dupacks = 0; 2668 break; 2669 } 2670 } 2671 /* Congestion signal before ack. */ 2672 cc_cong_signal(tp, th, CC_NDUPACK); 2673 cc_ack_received(tp, th, nsegs, 2674 CC_DUPACK); 2675 tcp_timer_activate(tp, TT_REXMT, 0); 2676 tp->t_rtttime = 0; 2677 if (V_tcp_do_prr) { 2678 /* 2679 * snd_ssthresh is already updated by 2680 * cc_cong_signal. 2681 */ 2682 if ((tp->t_flags & TF_SACK_PERMIT) && 2683 (to.to_flags & TOF_SACK)) { 2684 tp->sackhint.prr_delivered = 2685 tp->sackhint.sacked_bytes; 2686 } else { 2687 tp->sackhint.prr_delivered = 2688 imin(tp->snd_max - tp->snd_una, 2689 imin(INT_MAX / 65536, 2690 tp->t_dupacks) * maxseg); 2691 } 2692 tp->sackhint.recover_fs = max(1, 2693 tp->snd_nxt - tp->snd_una); 2694 } 2695 if ((tp->t_flags & TF_SACK_PERMIT) && 2696 (to.to_flags & TOF_SACK)) { 2697 TCPSTAT_INC( 2698 tcps_sack_recovery_episode); 2699 tp->snd_recover = tp->snd_nxt; 2700 tp->snd_cwnd = maxseg; 2701 (void) tcp_output(tp); 2702 if (SEQ_GT(th->th_ack, tp->snd_una)) 2703 goto resume_partialack; 2704 goto drop; 2705 } 2706 tp->snd_nxt = th->th_ack; 2707 tp->snd_cwnd = maxseg; 2708 (void) tcp_output(tp); 2709 KASSERT(tp->snd_limited <= 2, 2710 ("%s: tp->snd_limited too big", 2711 __func__)); 2712 tp->snd_cwnd = tp->snd_ssthresh + 2713 maxseg * 2714 (tp->t_dupacks - tp->snd_limited); 2715 if (SEQ_GT(onxt, tp->snd_nxt)) 2716 tp->snd_nxt = onxt; 2717 goto drop; 2718 } else if (V_tcp_do_rfc3042) { 2719 /* 2720 * Process first and second duplicate 2721 * ACKs. Each indicates a segment 2722 * leaving the network, creating room 2723 * for more. Make sure we can send a 2724 * packet on reception of each duplicate 2725 * ACK by increasing snd_cwnd by one 2726 * segment. Restore the original 2727 * snd_cwnd after packet transmission. 2728 */ 2729 cc_ack_received(tp, th, nsegs, 2730 CC_DUPACK); 2731 uint32_t oldcwnd = tp->snd_cwnd; 2732 tcp_seq oldsndmax = tp->snd_max; 2733 u_int sent; 2734 int avail; 2735 2736 KASSERT(tp->t_dupacks == 1 || 2737 tp->t_dupacks == 2, 2738 ("%s: dupacks not 1 or 2", 2739 __func__)); 2740 if (tp->t_dupacks == 1) 2741 tp->snd_limited = 0; 2742 tp->snd_cwnd = 2743 (tp->snd_nxt - tp->snd_una) + 2744 (tp->t_dupacks - tp->snd_limited) * 2745 maxseg; 2746 /* 2747 * Only call tcp_output when there 2748 * is new data available to be sent. 2749 * Otherwise we would send pure ACKs. 2750 */ 2751 SOCKBUF_LOCK(&so->so_snd); 2752 avail = sbavail(&so->so_snd) - 2753 (tp->snd_nxt - tp->snd_una); 2754 SOCKBUF_UNLOCK(&so->so_snd); 2755 if (avail > 0) 2756 (void) tcp_output(tp); 2757 sent = tp->snd_max - oldsndmax; 2758 if (sent > maxseg) { 2759 KASSERT((tp->t_dupacks == 2 && 2760 tp->snd_limited == 0) || 2761 (sent == maxseg + 1 && 2762 tp->t_flags & TF_SENTFIN), 2763 ("%s: sent too much", 2764 __func__)); 2765 tp->snd_limited = 2; 2766 } else if (sent > 0) 2767 ++tp->snd_limited; 2768 tp->snd_cwnd = oldcwnd; 2769 goto drop; 2770 } 2771 } 2772 break; 2773 } else { 2774 /* 2775 * This ack is advancing the left edge, reset the 2776 * counter. 2777 */ 2778 tp->t_dupacks = 0; 2779 /* 2780 * If this ack also has new SACK info, increment the 2781 * counter as per rfc6675. The variable 2782 * sack_changed tracks all changes to the SACK 2783 * scoreboard, including when partial ACKs without 2784 * SACK options are received, and clear the scoreboard 2785 * from the left side. Such partial ACKs should not be 2786 * counted as dupacks here. 2787 */ 2788 if ((tp->t_flags & TF_SACK_PERMIT) && 2789 (to.to_flags & TOF_SACK) && 2790 sack_changed) { 2791 tp->t_dupacks++; 2792 /* limit overhead by setting maxseg last */ 2793 if (!IN_FASTRECOVERY(tp->t_flags) && 2794 (tp->sackhint.sacked_bytes > 2795 ((tcprexmtthresh - 1) * 2796 (maxseg = tcp_maxseg(tp))))) { 2797 goto enter_recovery; 2798 } 2799 } 2800 } 2801 2802 resume_partialack: 2803 KASSERT(SEQ_GT(th->th_ack, tp->snd_una), 2804 ("%s: th_ack <= snd_una", __func__)); 2805 2806 /* 2807 * If the congestion window was inflated to account 2808 * for the other side's cached packets, retract it. 2809 */ 2810 if (IN_FASTRECOVERY(tp->t_flags)) { 2811 if (SEQ_LT(th->th_ack, tp->snd_recover)) { 2812 if (tp->t_flags & TF_SACK_PERMIT) 2813 if (V_tcp_do_prr && to.to_flags & TOF_SACK) { 2814 tcp_timer_activate(tp, TT_REXMT, 0); 2815 tp->t_rtttime = 0; 2816 tcp_do_prr_ack(tp, th, &to); 2817 tp->t_flags |= TF_ACKNOW; 2818 (void) tcp_output(tp); 2819 } else 2820 tcp_sack_partialack(tp, th); 2821 else 2822 tcp_newreno_partial_ack(tp, th); 2823 } else 2824 cc_post_recovery(tp, th); 2825 } else if (IN_CONGRECOVERY(tp->t_flags)) { 2826 if (SEQ_LT(th->th_ack, tp->snd_recover)) { 2827 if (V_tcp_do_prr) { 2828 tp->sackhint.delivered_data = BYTES_THIS_ACK(tp, th); 2829 tp->snd_fack = th->th_ack; 2830 tcp_do_prr_ack(tp, th, &to); 2831 (void) tcp_output(tp); 2832 } 2833 } else 2834 cc_post_recovery(tp, th); 2835 } 2836 /* 2837 * If we reach this point, ACK is not a duplicate, 2838 * i.e., it ACKs something we sent. 2839 */ 2840 if (tp->t_flags & TF_NEEDSYN) { 2841 /* 2842 * T/TCP: Connection was half-synchronized, and our 2843 * SYN has been ACK'd (so connection is now fully 2844 * synchronized). Go to non-starred state, 2845 * increment snd_una for ACK of SYN, and check if 2846 * we can do window scaling. 2847 */ 2848 tp->t_flags &= ~TF_NEEDSYN; 2849 tp->snd_una++; 2850 /* Do window scaling? */ 2851 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2852 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2853 tp->rcv_scale = tp->request_r_scale; 2854 /* Send window already scaled. */ 2855 } 2856 } 2857 2858 process_ACK: 2859 INP_WLOCK_ASSERT(tp->t_inpcb); 2860 2861 /* 2862 * Adjust for the SYN bit in sequence space, 2863 * but don't account for it in cwnd calculations. 2864 * This is for the SYN_RECEIVED, non-simultaneous 2865 * SYN case. SYN_SENT and simultaneous SYN are 2866 * treated elsewhere. 2867 */ 2868 if (incforsyn) 2869 tp->snd_una++; 2870 acked = BYTES_THIS_ACK(tp, th); 2871 KASSERT(acked >= 0, ("%s: acked unexepectedly negative " 2872 "(tp->snd_una=%u, th->th_ack=%u, tp=%p, m=%p)", __func__, 2873 tp->snd_una, th->th_ack, tp, m)); 2874 TCPSTAT_ADD(tcps_rcvackpack, nsegs); 2875 TCPSTAT_ADD(tcps_rcvackbyte, acked); 2876 2877 /* 2878 * If we just performed our first retransmit, and the ACK 2879 * arrives within our recovery window, then it was a mistake 2880 * to do the retransmit in the first place. Recover our 2881 * original cwnd and ssthresh, and proceed to transmit where 2882 * we left off. 2883 */ 2884 if (tp->t_rxtshift == 1 && 2885 tp->t_flags & TF_PREVVALID && 2886 tp->t_badrxtwin && 2887 SEQ_LT(to.to_tsecr, tp->t_badrxtwin)) 2888 cc_cong_signal(tp, th, CC_RTO_ERR); 2889 2890 /* 2891 * If we have a timestamp reply, update smoothed 2892 * round trip time. If no timestamp is present but 2893 * transmit timer is running and timed sequence 2894 * number was acked, update smoothed round trip time. 2895 * Since we now have an rtt measurement, cancel the 2896 * timer backoff (cf., Phil Karn's retransmit alg.). 2897 * Recompute the initial retransmit timer. 2898 * 2899 * Some boxes send broken timestamp replies 2900 * during the SYN+ACK phase, ignore 2901 * timestamps of 0 or we could calculate a 2902 * huge RTT and blow up the retransmit timer. 2903 */ 2904 if ((to.to_flags & TOF_TS) != 0 && to.to_tsecr) { 2905 uint32_t t; 2906 2907 t = tcp_ts_getticks() - to.to_tsecr; 2908 if (!tp->t_rttlow || tp->t_rttlow > t) 2909 tp->t_rttlow = t; 2910 tcp_xmit_timer(tp, TCP_TS_TO_TICKS(t) + 1); 2911 } else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) { 2912 if (!tp->t_rttlow || tp->t_rttlow > ticks - tp->t_rtttime) 2913 tp->t_rttlow = ticks - tp->t_rtttime; 2914 tcp_xmit_timer(tp, ticks - tp->t_rtttime); 2915 } 2916 2917 /* 2918 * If all outstanding data is acked, stop retransmit 2919 * timer and remember to restart (more output or persist). 2920 * If there is more data to be acked, restart retransmit 2921 * timer, using current (possibly backed-off) value. 2922 */ 2923 if (th->th_ack == tp->snd_max) { 2924 tcp_timer_activate(tp, TT_REXMT, 0); 2925 needoutput = 1; 2926 } else if (!tcp_timer_active(tp, TT_PERSIST)) 2927 tcp_timer_activate(tp, TT_REXMT, tp->t_rxtcur); 2928 2929 /* 2930 * If no data (only SYN) was ACK'd, 2931 * skip rest of ACK processing. 2932 */ 2933 if (acked == 0) 2934 goto step6; 2935 2936 /* 2937 * Let the congestion control algorithm update congestion 2938 * control related information. This typically means increasing 2939 * the congestion window. 2940 */ 2941 cc_ack_received(tp, th, nsegs, CC_ACK); 2942 2943 SOCKBUF_LOCK(&so->so_snd); 2944 if (acked > sbavail(&so->so_snd)) { 2945 if (tp->snd_wnd >= sbavail(&so->so_snd)) 2946 tp->snd_wnd -= sbavail(&so->so_snd); 2947 else 2948 tp->snd_wnd = 0; 2949 mfree = sbcut_locked(&so->so_snd, 2950 (int)sbavail(&so->so_snd)); 2951 ourfinisacked = 1; 2952 } else { 2953 mfree = sbcut_locked(&so->so_snd, acked); 2954 if (tp->snd_wnd >= (uint32_t) acked) 2955 tp->snd_wnd -= acked; 2956 else 2957 tp->snd_wnd = 0; 2958 ourfinisacked = 0; 2959 } 2960 /* NB: sowwakeup_locked() does an implicit unlock. */ 2961 sowwakeup_locked(so); 2962 m_freem(mfree); 2963 /* Detect una wraparound. */ 2964 if (!IN_RECOVERY(tp->t_flags) && 2965 SEQ_GT(tp->snd_una, tp->snd_recover) && 2966 SEQ_LEQ(th->th_ack, tp->snd_recover)) 2967 tp->snd_recover = th->th_ack - 1; 2968 /* XXXLAS: Can this be moved up into cc_post_recovery? */ 2969 if (IN_RECOVERY(tp->t_flags) && 2970 SEQ_GEQ(th->th_ack, tp->snd_recover)) { 2971 EXIT_RECOVERY(tp->t_flags); 2972 } 2973 tp->snd_una = th->th_ack; 2974 if (tp->t_flags & TF_SACK_PERMIT) { 2975 if (SEQ_GT(tp->snd_una, tp->snd_recover)) 2976 tp->snd_recover = tp->snd_una; 2977 } 2978 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2979 tp->snd_nxt = tp->snd_una; 2980 2981 switch (tp->t_state) { 2982 /* 2983 * In FIN_WAIT_1 STATE in addition to the processing 2984 * for the ESTABLISHED state if our FIN is now acknowledged 2985 * then enter FIN_WAIT_2. 2986 */ 2987 case TCPS_FIN_WAIT_1: 2988 if (ourfinisacked) { 2989 /* 2990 * If we can't receive any more 2991 * data, then closing user can proceed. 2992 * Starting the timer is contrary to the 2993 * specification, but if we don't get a FIN 2994 * we'll hang forever. 2995 * 2996 * XXXjl: 2997 * we should release the tp also, and use a 2998 * compressed state. 2999 */ 3000 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 3001 soisdisconnected(so); 3002 tcp_timer_activate(tp, TT_2MSL, 3003 (tcp_fast_finwait2_recycle ? 3004 tcp_finwait2_timeout : 3005 TP_MAXIDLE(tp))); 3006 } 3007 tcp_state_change(tp, TCPS_FIN_WAIT_2); 3008 } 3009 break; 3010 3011 /* 3012 * In CLOSING STATE in addition to the processing for 3013 * the ESTABLISHED state if the ACK acknowledges our FIN 3014 * then enter the TIME-WAIT state, otherwise ignore 3015 * the segment. 3016 */ 3017 case TCPS_CLOSING: 3018 if (ourfinisacked) { 3019 tcp_twstart(tp); 3020 m_freem(m); 3021 return; 3022 } 3023 break; 3024 3025 /* 3026 * In LAST_ACK, we may still be waiting for data to drain 3027 * and/or to be acked, as well as for the ack of our FIN. 3028 * If our FIN is now acknowledged, delete the TCB, 3029 * enter the closed state and return. 3030 */ 3031 case TCPS_LAST_ACK: 3032 if (ourfinisacked) { 3033 tp = tcp_close(tp); 3034 goto drop; 3035 } 3036 break; 3037 } 3038 } 3039 3040 step6: 3041 INP_WLOCK_ASSERT(tp->t_inpcb); 3042 3043 /* 3044 * Update window information. 3045 * Don't look at window if no ACK: TAC's send garbage on first SYN. 3046 */ 3047 if ((thflags & TH_ACK) && 3048 (SEQ_LT(tp->snd_wl1, th->th_seq) || 3049 (tp->snd_wl1 == th->th_seq && (SEQ_LT(tp->snd_wl2, th->th_ack) || 3050 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))) { 3051 /* keep track of pure window updates */ 3052 if (tlen == 0 && 3053 tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) 3054 TCPSTAT_INC(tcps_rcvwinupd); 3055 tp->snd_wnd = tiwin; 3056 tp->snd_wl1 = th->th_seq; 3057 tp->snd_wl2 = th->th_ack; 3058 if (tp->snd_wnd > tp->max_sndwnd) 3059 tp->max_sndwnd = tp->snd_wnd; 3060 needoutput = 1; 3061 } 3062 3063 /* 3064 * Process segments with URG. 3065 */ 3066 if ((thflags & TH_URG) && th->th_urp && 3067 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3068 /* 3069 * This is a kludge, but if we receive and accept 3070 * random urgent pointers, we'll crash in 3071 * soreceive. It's hard to imagine someone 3072 * actually wanting to send this much urgent data. 3073 */ 3074 SOCKBUF_LOCK(&so->so_rcv); 3075 if (th->th_urp + sbavail(&so->so_rcv) > sb_max) { 3076 th->th_urp = 0; /* XXX */ 3077 thflags &= ~TH_URG; /* XXX */ 3078 SOCKBUF_UNLOCK(&so->so_rcv); /* XXX */ 3079 goto dodata; /* XXX */ 3080 } 3081 /* 3082 * If this segment advances the known urgent pointer, 3083 * then mark the data stream. This should not happen 3084 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 3085 * a FIN has been received from the remote side. 3086 * In these states we ignore the URG. 3087 * 3088 * According to RFC961 (Assigned Protocols), 3089 * the urgent pointer points to the last octet 3090 * of urgent data. We continue, however, 3091 * to consider it to indicate the first octet 3092 * of data past the urgent section as the original 3093 * spec states (in one of two places). 3094 */ 3095 if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) { 3096 tp->rcv_up = th->th_seq + th->th_urp; 3097 so->so_oobmark = sbavail(&so->so_rcv) + 3098 (tp->rcv_up - tp->rcv_nxt) - 1; 3099 if (so->so_oobmark == 0) 3100 so->so_rcv.sb_state |= SBS_RCVATMARK; 3101 sohasoutofband(so); 3102 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); 3103 } 3104 SOCKBUF_UNLOCK(&so->so_rcv); 3105 /* 3106 * Remove out of band data so doesn't get presented to user. 3107 * This can happen independent of advancing the URG pointer, 3108 * but if two URG's are pending at once, some out-of-band 3109 * data may creep in... ick. 3110 */ 3111 if (th->th_urp <= (uint32_t)tlen && 3112 !(so->so_options & SO_OOBINLINE)) { 3113 /* hdr drop is delayed */ 3114 tcp_pulloutofband(so, th, m, drop_hdrlen); 3115 } 3116 } else { 3117 /* 3118 * If no out of band data is expected, 3119 * pull receive urgent pointer along 3120 * with the receive window. 3121 */ 3122 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) 3123 tp->rcv_up = tp->rcv_nxt; 3124 } 3125 dodata: /* XXX */ 3126 INP_WLOCK_ASSERT(tp->t_inpcb); 3127 3128 /* 3129 * Process the segment text, merging it into the TCP sequencing queue, 3130 * and arranging for acknowledgment of receipt if necessary. 3131 * This process logically involves adjusting tp->rcv_wnd as data 3132 * is presented to the user (this happens in tcp_usrreq.c, 3133 * case PRU_RCVD). If a FIN has already been received on this 3134 * connection then we just ignore the text. 3135 */ 3136 tfo_syn = ((tp->t_state == TCPS_SYN_RECEIVED) && 3137 IS_FASTOPEN(tp->t_flags)); 3138 if ((tlen || (thflags & TH_FIN) || (tfo_syn && tlen > 0)) && 3139 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3140 tcp_seq save_start = th->th_seq; 3141 tcp_seq save_rnxt = tp->rcv_nxt; 3142 int save_tlen = tlen; 3143 m_adj(m, drop_hdrlen); /* delayed header drop */ 3144 /* 3145 * Insert segment which includes th into TCP reassembly queue 3146 * with control block tp. Set thflags to whether reassembly now 3147 * includes a segment with FIN. This handles the common case 3148 * inline (segment is the next to be received on an established 3149 * connection, and the queue is empty), avoiding linkage into 3150 * and removal from the queue and repetition of various 3151 * conversions. 3152 * Set DELACK for segments received in order, but ack 3153 * immediately when segments are out of order (so 3154 * fast retransmit can work). 3155 */ 3156 if (th->th_seq == tp->rcv_nxt && 3157 SEGQ_EMPTY(tp) && 3158 (TCPS_HAVEESTABLISHED(tp->t_state) || 3159 tfo_syn)) { 3160 if (DELAY_ACK(tp, tlen) || tfo_syn) 3161 tp->t_flags |= TF_DELACK; 3162 else 3163 tp->t_flags |= TF_ACKNOW; 3164 tp->rcv_nxt += tlen; 3165 if (tlen && 3166 ((tp->t_flags2 & TF2_FBYTES_COMPLETE) == 0) && 3167 (tp->t_fbyte_in == 0)) { 3168 tp->t_fbyte_in = ticks; 3169 if (tp->t_fbyte_in == 0) 3170 tp->t_fbyte_in = 1; 3171 if (tp->t_fbyte_out && tp->t_fbyte_in) 3172 tp->t_flags2 |= TF2_FBYTES_COMPLETE; 3173 } 3174 thflags = th->th_flags & TH_FIN; 3175 TCPSTAT_INC(tcps_rcvpack); 3176 TCPSTAT_ADD(tcps_rcvbyte, tlen); 3177 SOCKBUF_LOCK(&so->so_rcv); 3178 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) 3179 m_freem(m); 3180 else 3181 sbappendstream_locked(&so->so_rcv, m, 0); 3182 tp->t_flags |= TF_WAKESOR; 3183 } else { 3184 /* 3185 * XXX: Due to the header drop above "th" is 3186 * theoretically invalid by now. Fortunately 3187 * m_adj() doesn't actually frees any mbufs 3188 * when trimming from the head. 3189 */ 3190 tcp_seq temp = save_start; 3191 3192 thflags = tcp_reass(tp, th, &temp, &tlen, m); 3193 tp->t_flags |= TF_ACKNOW; 3194 } 3195 if ((tp->t_flags & TF_SACK_PERMIT) && 3196 (save_tlen > 0) && 3197 TCPS_HAVEESTABLISHED(tp->t_state)) { 3198 if ((tlen == 0) && (SEQ_LT(save_start, save_rnxt))) { 3199 /* 3200 * DSACK actually handled in the fastpath 3201 * above. 3202 */ 3203 tcp_update_sack_list(tp, save_start, 3204 save_start + save_tlen); 3205 } else if ((tlen > 0) && SEQ_GT(tp->rcv_nxt, save_rnxt)) { 3206 if ((tp->rcv_numsacks >= 1) && 3207 (tp->sackblks[0].end == save_start)) { 3208 /* 3209 * Partial overlap, recorded at todrop 3210 * above. 3211 */ 3212 tcp_update_sack_list(tp, 3213 tp->sackblks[0].start, 3214 tp->sackblks[0].end); 3215 } else { 3216 tcp_update_dsack_list(tp, save_start, 3217 save_start + save_tlen); 3218 } 3219 } else if (tlen >= save_tlen) { 3220 /* Update of sackblks. */ 3221 tcp_update_dsack_list(tp, save_start, 3222 save_start + save_tlen); 3223 } else if (tlen > 0) { 3224 tcp_update_dsack_list(tp, save_start, 3225 save_start + tlen); 3226 } 3227 } 3228 tcp_handle_wakeup(tp, so); 3229 #if 0 3230 /* 3231 * Note the amount of data that peer has sent into 3232 * our window, in order to estimate the sender's 3233 * buffer size. 3234 * XXX: Unused. 3235 */ 3236 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt)) 3237 len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); 3238 else 3239 len = so->so_rcv.sb_hiwat; 3240 #endif 3241 } else { 3242 m_freem(m); 3243 thflags &= ~TH_FIN; 3244 } 3245 3246 /* 3247 * If FIN is received ACK the FIN and let the user know 3248 * that the connection is closing. 3249 */ 3250 if (thflags & TH_FIN) { 3251 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3252 /* The socket upcall is handled by socantrcvmore. */ 3253 socantrcvmore(so); 3254 /* 3255 * If connection is half-synchronized 3256 * (ie NEEDSYN flag on) then delay ACK, 3257 * so it may be piggybacked when SYN is sent. 3258 * Otherwise, since we received a FIN then no 3259 * more input can be expected, send ACK now. 3260 */ 3261 if (tp->t_flags & TF_NEEDSYN) 3262 tp->t_flags |= TF_DELACK; 3263 else 3264 tp->t_flags |= TF_ACKNOW; 3265 tp->rcv_nxt++; 3266 } 3267 switch (tp->t_state) { 3268 /* 3269 * In SYN_RECEIVED and ESTABLISHED STATES 3270 * enter the CLOSE_WAIT state. 3271 */ 3272 case TCPS_SYN_RECEIVED: 3273 tp->t_starttime = ticks; 3274 /* FALLTHROUGH */ 3275 case TCPS_ESTABLISHED: 3276 tcp_state_change(tp, TCPS_CLOSE_WAIT); 3277 break; 3278 3279 /* 3280 * If still in FIN_WAIT_1 STATE FIN has not been acked so 3281 * enter the CLOSING state. 3282 */ 3283 case TCPS_FIN_WAIT_1: 3284 tcp_state_change(tp, TCPS_CLOSING); 3285 break; 3286 3287 /* 3288 * In FIN_WAIT_2 state enter the TIME_WAIT state, 3289 * starting the time-wait timer, turning off the other 3290 * standard timers. 3291 */ 3292 case TCPS_FIN_WAIT_2: 3293 tcp_twstart(tp); 3294 return; 3295 } 3296 } 3297 #ifdef TCPDEBUG 3298 if (so->so_options & SO_DEBUG) 3299 tcp_trace(TA_INPUT, ostate, tp, (void *)tcp_saveipgen, 3300 &tcp_savetcp, 0); 3301 #endif 3302 TCP_PROBE3(debug__input, tp, th, m); 3303 3304 /* 3305 * Return any desired output. 3306 */ 3307 if (needoutput || (tp->t_flags & TF_ACKNOW)) 3308 (void) tcp_output(tp); 3309 3310 check_delack: 3311 INP_WLOCK_ASSERT(tp->t_inpcb); 3312 3313 if (tp->t_flags & TF_DELACK) { 3314 tp->t_flags &= ~TF_DELACK; 3315 tcp_timer_activate(tp, TT_DELACK, tcp_delacktime); 3316 } 3317 INP_WUNLOCK(tp->t_inpcb); 3318 return; 3319 3320 dropafterack: 3321 /* 3322 * Generate an ACK dropping incoming segment if it occupies 3323 * sequence space, where the ACK reflects our state. 3324 * 3325 * We can now skip the test for the RST flag since all 3326 * paths to this code happen after packets containing 3327 * RST have been dropped. 3328 * 3329 * In the SYN-RECEIVED state, don't send an ACK unless the 3330 * segment we received passes the SYN-RECEIVED ACK test. 3331 * If it fails send a RST. This breaks the loop in the 3332 * "LAND" DoS attack, and also prevents an ACK storm 3333 * between two listening ports that have been sent forged 3334 * SYN segments, each with the source address of the other. 3335 */ 3336 if (tp->t_state == TCPS_SYN_RECEIVED && (thflags & TH_ACK) && 3337 (SEQ_GT(tp->snd_una, th->th_ack) || 3338 SEQ_GT(th->th_ack, tp->snd_max)) ) { 3339 rstreason = BANDLIM_RST_OPENPORT; 3340 goto dropwithreset; 3341 } 3342 #ifdef TCPDEBUG 3343 if (so->so_options & SO_DEBUG) 3344 tcp_trace(TA_DROP, ostate, tp, (void *)tcp_saveipgen, 3345 &tcp_savetcp, 0); 3346 #endif 3347 TCP_PROBE3(debug__input, tp, th, m); 3348 tp->t_flags |= TF_ACKNOW; 3349 (void) tcp_output(tp); 3350 INP_WUNLOCK(tp->t_inpcb); 3351 m_freem(m); 3352 return; 3353 3354 dropwithreset: 3355 if (tp != NULL) { 3356 tcp_dropwithreset(m, th, tp, tlen, rstreason); 3357 INP_WUNLOCK(tp->t_inpcb); 3358 } else 3359 tcp_dropwithreset(m, th, NULL, tlen, rstreason); 3360 return; 3361 3362 drop: 3363 /* 3364 * Drop space held by incoming segment and return. 3365 */ 3366 #ifdef TCPDEBUG 3367 if (tp == NULL || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 3368 tcp_trace(TA_DROP, ostate, tp, (void *)tcp_saveipgen, 3369 &tcp_savetcp, 0); 3370 #endif 3371 TCP_PROBE3(debug__input, tp, th, m); 3372 if (tp != NULL) { 3373 INP_WUNLOCK(tp->t_inpcb); 3374 } 3375 m_freem(m); 3376 } 3377 3378 /* 3379 * Issue RST and make ACK acceptable to originator of segment. 3380 * The mbuf must still include the original packet header. 3381 * tp may be NULL. 3382 */ 3383 void 3384 tcp_dropwithreset(struct mbuf *m, struct tcphdr *th, struct tcpcb *tp, 3385 int tlen, int rstreason) 3386 { 3387 #ifdef INET 3388 struct ip *ip; 3389 #endif 3390 #ifdef INET6 3391 struct ip6_hdr *ip6; 3392 #endif 3393 3394 if (tp != NULL) { 3395 INP_LOCK_ASSERT(tp->t_inpcb); 3396 } 3397 3398 /* Don't bother if destination was broadcast/multicast. */ 3399 if ((th->th_flags & TH_RST) || m->m_flags & (M_BCAST|M_MCAST)) 3400 goto drop; 3401 #ifdef INET6 3402 if (mtod(m, struct ip *)->ip_v == 6) { 3403 ip6 = mtod(m, struct ip6_hdr *); 3404 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 3405 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) 3406 goto drop; 3407 /* IPv6 anycast check is done at tcp6_input() */ 3408 } 3409 #endif 3410 #if defined(INET) && defined(INET6) 3411 else 3412 #endif 3413 #ifdef INET 3414 { 3415 ip = mtod(m, struct ip *); 3416 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || 3417 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 3418 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || 3419 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 3420 goto drop; 3421 } 3422 #endif 3423 3424 /* Perform bandwidth limiting. */ 3425 if (badport_bandlim(rstreason) < 0) 3426 goto drop; 3427 3428 /* tcp_respond consumes the mbuf chain. */ 3429 if (th->th_flags & TH_ACK) { 3430 tcp_respond(tp, mtod(m, void *), th, m, (tcp_seq)0, 3431 th->th_ack, TH_RST); 3432 } else { 3433 if (th->th_flags & TH_SYN) 3434 tlen++; 3435 if (th->th_flags & TH_FIN) 3436 tlen++; 3437 tcp_respond(tp, mtod(m, void *), th, m, th->th_seq+tlen, 3438 (tcp_seq)0, TH_RST|TH_ACK); 3439 } 3440 return; 3441 drop: 3442 m_freem(m); 3443 } 3444 3445 /* 3446 * Parse TCP options and place in tcpopt. 3447 */ 3448 void 3449 tcp_dooptions(struct tcpopt *to, u_char *cp, int cnt, int flags) 3450 { 3451 int opt, optlen; 3452 3453 to->to_flags = 0; 3454 for (; cnt > 0; cnt -= optlen, cp += optlen) { 3455 opt = cp[0]; 3456 if (opt == TCPOPT_EOL) 3457 break; 3458 if (opt == TCPOPT_NOP) 3459 optlen = 1; 3460 else { 3461 if (cnt < 2) 3462 break; 3463 optlen = cp[1]; 3464 if (optlen < 2 || optlen > cnt) 3465 break; 3466 } 3467 switch (opt) { 3468 case TCPOPT_MAXSEG: 3469 if (optlen != TCPOLEN_MAXSEG) 3470 continue; 3471 if (!(flags & TO_SYN)) 3472 continue; 3473 to->to_flags |= TOF_MSS; 3474 bcopy((char *)cp + 2, 3475 (char *)&to->to_mss, sizeof(to->to_mss)); 3476 to->to_mss = ntohs(to->to_mss); 3477 break; 3478 case TCPOPT_WINDOW: 3479 if (optlen != TCPOLEN_WINDOW) 3480 continue; 3481 if (!(flags & TO_SYN)) 3482 continue; 3483 to->to_flags |= TOF_SCALE; 3484 to->to_wscale = min(cp[2], TCP_MAX_WINSHIFT); 3485 break; 3486 case TCPOPT_TIMESTAMP: 3487 if (optlen != TCPOLEN_TIMESTAMP) 3488 continue; 3489 to->to_flags |= TOF_TS; 3490 bcopy((char *)cp + 2, 3491 (char *)&to->to_tsval, sizeof(to->to_tsval)); 3492 to->to_tsval = ntohl(to->to_tsval); 3493 bcopy((char *)cp + 6, 3494 (char *)&to->to_tsecr, sizeof(to->to_tsecr)); 3495 to->to_tsecr = ntohl(to->to_tsecr); 3496 break; 3497 case TCPOPT_SIGNATURE: 3498 /* 3499 * In order to reply to a host which has set the 3500 * TCP_SIGNATURE option in its initial SYN, we have 3501 * to record the fact that the option was observed 3502 * here for the syncache code to perform the correct 3503 * response. 3504 */ 3505 if (optlen != TCPOLEN_SIGNATURE) 3506 continue; 3507 to->to_flags |= TOF_SIGNATURE; 3508 to->to_signature = cp + 2; 3509 break; 3510 case TCPOPT_SACK_PERMITTED: 3511 if (optlen != TCPOLEN_SACK_PERMITTED) 3512 continue; 3513 if (!(flags & TO_SYN)) 3514 continue; 3515 if (!V_tcp_do_sack) 3516 continue; 3517 to->to_flags |= TOF_SACKPERM; 3518 break; 3519 case TCPOPT_SACK: 3520 if (optlen <= 2 || (optlen - 2) % TCPOLEN_SACK != 0) 3521 continue; 3522 if (flags & TO_SYN) 3523 continue; 3524 to->to_flags |= TOF_SACK; 3525 to->to_nsacks = (optlen - 2) / TCPOLEN_SACK; 3526 to->to_sacks = cp + 2; 3527 TCPSTAT_INC(tcps_sack_rcv_blocks); 3528 break; 3529 case TCPOPT_FAST_OPEN: 3530 /* 3531 * Cookie length validation is performed by the 3532 * server side cookie checking code or the client 3533 * side cookie cache update code. 3534 */ 3535 if (!(flags & TO_SYN)) 3536 continue; 3537 if (!V_tcp_fastopen_client_enable && 3538 !V_tcp_fastopen_server_enable) 3539 continue; 3540 to->to_flags |= TOF_FASTOPEN; 3541 to->to_tfo_len = optlen - 2; 3542 to->to_tfo_cookie = to->to_tfo_len ? cp + 2 : NULL; 3543 break; 3544 default: 3545 continue; 3546 } 3547 } 3548 } 3549 3550 /* 3551 * Pull out of band byte out of a segment so 3552 * it doesn't appear in the user's data queue. 3553 * It is still reflected in the segment length for 3554 * sequencing purposes. 3555 */ 3556 void 3557 tcp_pulloutofband(struct socket *so, struct tcphdr *th, struct mbuf *m, 3558 int off) 3559 { 3560 int cnt = off + th->th_urp - 1; 3561 3562 while (cnt >= 0) { 3563 if (m->m_len > cnt) { 3564 char *cp = mtod(m, caddr_t) + cnt; 3565 struct tcpcb *tp = sototcpcb(so); 3566 3567 INP_WLOCK_ASSERT(tp->t_inpcb); 3568 3569 tp->t_iobc = *cp; 3570 tp->t_oobflags |= TCPOOB_HAVEDATA; 3571 bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); 3572 m->m_len--; 3573 if (m->m_flags & M_PKTHDR) 3574 m->m_pkthdr.len--; 3575 return; 3576 } 3577 cnt -= m->m_len; 3578 m = m->m_next; 3579 if (m == NULL) 3580 break; 3581 } 3582 panic("tcp_pulloutofband"); 3583 } 3584 3585 /* 3586 * Collect new round-trip time estimate 3587 * and update averages and current timeout. 3588 */ 3589 void 3590 tcp_xmit_timer(struct tcpcb *tp, int rtt) 3591 { 3592 int delta; 3593 3594 INP_WLOCK_ASSERT(tp->t_inpcb); 3595 3596 TCPSTAT_INC(tcps_rttupdated); 3597 tp->t_rttupdated++; 3598 #ifdef STATS 3599 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_RTT, 3600 imax(0, rtt * 1000 / hz)); 3601 #endif 3602 if ((tp->t_srtt != 0) && (tp->t_rxtshift <= TCP_RTT_INVALIDATE)) { 3603 /* 3604 * srtt is stored as fixed point with 5 bits after the 3605 * binary point (i.e., scaled by 8). The following magic 3606 * is equivalent to the smoothing algorithm in rfc793 with 3607 * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed 3608 * point). Adjust rtt to origin 0. 3609 */ 3610 delta = ((rtt - 1) << TCP_DELTA_SHIFT) 3611 - (tp->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT)); 3612 3613 if ((tp->t_srtt += delta) <= 0) 3614 tp->t_srtt = 1; 3615 3616 /* 3617 * We accumulate a smoothed rtt variance (actually, a 3618 * smoothed mean difference), then set the retransmit 3619 * timer to smoothed rtt + 4 times the smoothed variance. 3620 * rttvar is stored as fixed point with 4 bits after the 3621 * binary point (scaled by 16). The following is 3622 * equivalent to rfc793 smoothing with an alpha of .75 3623 * (rttvar = rttvar*3/4 + |delta| / 4). This replaces 3624 * rfc793's wired-in beta. 3625 */ 3626 if (delta < 0) 3627 delta = -delta; 3628 delta -= tp->t_rttvar >> (TCP_RTTVAR_SHIFT - TCP_DELTA_SHIFT); 3629 if ((tp->t_rttvar += delta) <= 0) 3630 tp->t_rttvar = 1; 3631 if (tp->t_rttbest > tp->t_srtt + tp->t_rttvar) 3632 tp->t_rttbest = tp->t_srtt + tp->t_rttvar; 3633 } else { 3634 /* 3635 * No rtt measurement yet - use the unsmoothed rtt. 3636 * Set the variance to half the rtt (so our first 3637 * retransmit happens at 3*rtt). 3638 */ 3639 tp->t_srtt = rtt << TCP_RTT_SHIFT; 3640 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1); 3641 tp->t_rttbest = tp->t_srtt + tp->t_rttvar; 3642 } 3643 tp->t_rtttime = 0; 3644 tp->t_rxtshift = 0; 3645 3646 /* 3647 * the retransmit should happen at rtt + 4 * rttvar. 3648 * Because of the way we do the smoothing, srtt and rttvar 3649 * will each average +1/2 tick of bias. When we compute 3650 * the retransmit timer, we want 1/2 tick of rounding and 3651 * 1 extra tick because of +-1/2 tick uncertainty in the 3652 * firing of the timer. The bias will give us exactly the 3653 * 1.5 tick we need. But, because the bias is 3654 * statistical, we have to test that we don't drop below 3655 * the minimum feasible timer (which is 2 ticks). 3656 */ 3657 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), 3658 max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX); 3659 3660 /* 3661 * We received an ack for a packet that wasn't retransmitted; 3662 * it is probably safe to discard any error indications we've 3663 * received recently. This isn't quite right, but close enough 3664 * for now (a route might have failed after we sent a segment, 3665 * and the return path might not be symmetrical). 3666 */ 3667 tp->t_softerror = 0; 3668 } 3669 3670 /* 3671 * Determine a reasonable value for maxseg size. 3672 * If the route is known, check route for mtu. 3673 * If none, use an mss that can be handled on the outgoing interface 3674 * without forcing IP to fragment. If no route is found, route has no mtu, 3675 * or the destination isn't local, use a default, hopefully conservative 3676 * size (usually 512 or the default IP max size, but no more than the mtu 3677 * of the interface), as we can't discover anything about intervening 3678 * gateways or networks. We also initialize the congestion/slow start 3679 * window to be a single segment if the destination isn't local. 3680 * While looking at the routing entry, we also initialize other path-dependent 3681 * parameters from pre-set or cached values in the routing entry. 3682 * 3683 * NOTE that resulting t_maxseg doesn't include space for TCP options or 3684 * IP options, e.g. IPSEC data, since length of this data may vary, and 3685 * thus it is calculated for every segment separately in tcp_output(). 3686 * 3687 * NOTE that this routine is only called when we process an incoming 3688 * segment, or an ICMP need fragmentation datagram. Outgoing SYN/ACK MSS 3689 * settings are handled in tcp_mssopt(). 3690 */ 3691 void 3692 tcp_mss_update(struct tcpcb *tp, int offer, int mtuoffer, 3693 struct hc_metrics_lite *metricptr, struct tcp_ifcap *cap) 3694 { 3695 int mss = 0; 3696 uint32_t maxmtu = 0; 3697 struct inpcb *inp = tp->t_inpcb; 3698 struct hc_metrics_lite metrics; 3699 #ifdef INET6 3700 int isipv6 = ((inp->inp_vflag & INP_IPV6) != 0) ? 1 : 0; 3701 size_t min_protoh = isipv6 ? 3702 sizeof (struct ip6_hdr) + sizeof (struct tcphdr) : 3703 sizeof (struct tcpiphdr); 3704 #else 3705 size_t min_protoh = sizeof(struct tcpiphdr); 3706 #endif 3707 3708 INP_WLOCK_ASSERT(tp->t_inpcb); 3709 3710 if (tp->t_port) 3711 min_protoh += V_tcp_udp_tunneling_overhead; 3712 if (mtuoffer != -1) { 3713 KASSERT(offer == -1, ("%s: conflict", __func__)); 3714 offer = mtuoffer - min_protoh; 3715 } 3716 3717 /* Initialize. */ 3718 #ifdef INET6 3719 if (isipv6) { 3720 maxmtu = tcp_maxmtu6(&inp->inp_inc, cap); 3721 tp->t_maxseg = V_tcp_v6mssdflt; 3722 } 3723 #endif 3724 #if defined(INET) && defined(INET6) 3725 else 3726 #endif 3727 #ifdef INET 3728 { 3729 maxmtu = tcp_maxmtu(&inp->inp_inc, cap); 3730 tp->t_maxseg = V_tcp_mssdflt; 3731 } 3732 #endif 3733 3734 /* 3735 * No route to sender, stay with default mss and return. 3736 */ 3737 if (maxmtu == 0) { 3738 /* 3739 * In case we return early we need to initialize metrics 3740 * to a defined state as tcp_hc_get() would do for us 3741 * if there was no cache hit. 3742 */ 3743 if (metricptr != NULL) 3744 bzero(metricptr, sizeof(struct hc_metrics_lite)); 3745 return; 3746 } 3747 3748 /* What have we got? */ 3749 switch (offer) { 3750 case 0: 3751 /* 3752 * Offer == 0 means that there was no MSS on the SYN 3753 * segment, in this case we use tcp_mssdflt as 3754 * already assigned to t_maxseg above. 3755 */ 3756 offer = tp->t_maxseg; 3757 break; 3758 3759 case -1: 3760 /* 3761 * Offer == -1 means that we didn't receive SYN yet. 3762 */ 3763 /* FALLTHROUGH */ 3764 3765 default: 3766 /* 3767 * Prevent DoS attack with too small MSS. Round up 3768 * to at least minmss. 3769 */ 3770 offer = max(offer, V_tcp_minmss); 3771 } 3772 3773 /* 3774 * rmx information is now retrieved from tcp_hostcache. 3775 */ 3776 tcp_hc_get(&inp->inp_inc, &metrics); 3777 if (metricptr != NULL) 3778 bcopy(&metrics, metricptr, sizeof(struct hc_metrics_lite)); 3779 3780 /* 3781 * If there's a discovered mtu in tcp hostcache, use it. 3782 * Else, use the link mtu. 3783 */ 3784 if (metrics.rmx_mtu) 3785 mss = min(metrics.rmx_mtu, maxmtu) - min_protoh; 3786 else { 3787 #ifdef INET6 3788 if (isipv6) { 3789 mss = maxmtu - min_protoh; 3790 if (!V_path_mtu_discovery && 3791 !in6_localaddr(&inp->in6p_faddr)) 3792 mss = min(mss, V_tcp_v6mssdflt); 3793 } 3794 #endif 3795 #if defined(INET) && defined(INET6) 3796 else 3797 #endif 3798 #ifdef INET 3799 { 3800 mss = maxmtu - min_protoh; 3801 if (!V_path_mtu_discovery && 3802 !in_localaddr(inp->inp_faddr)) 3803 mss = min(mss, V_tcp_mssdflt); 3804 } 3805 #endif 3806 /* 3807 * XXX - The above conditional (mss = maxmtu - min_protoh) 3808 * probably violates the TCP spec. 3809 * The problem is that, since we don't know the 3810 * other end's MSS, we are supposed to use a conservative 3811 * default. But, if we do that, then MTU discovery will 3812 * never actually take place, because the conservative 3813 * default is much less than the MTUs typically seen 3814 * on the Internet today. For the moment, we'll sweep 3815 * this under the carpet. 3816 * 3817 * The conservative default might not actually be a problem 3818 * if the only case this occurs is when sending an initial 3819 * SYN with options and data to a host we've never talked 3820 * to before. Then, they will reply with an MSS value which 3821 * will get recorded and the new parameters should get 3822 * recomputed. For Further Study. 3823 */ 3824 } 3825 mss = min(mss, offer); 3826 3827 /* 3828 * Sanity check: make sure that maxseg will be large 3829 * enough to allow some data on segments even if the 3830 * all the option space is used (40bytes). Otherwise 3831 * funny things may happen in tcp_output. 3832 * 3833 * XXXGL: shouldn't we reserve space for IP/IPv6 options? 3834 */ 3835 mss = max(mss, 64); 3836 3837 tp->t_maxseg = mss; 3838 } 3839 3840 void 3841 tcp_mss(struct tcpcb *tp, int offer) 3842 { 3843 int mss; 3844 uint32_t bufsize; 3845 struct inpcb *inp; 3846 struct socket *so; 3847 struct hc_metrics_lite metrics; 3848 struct tcp_ifcap cap; 3849 3850 KASSERT(tp != NULL, ("%s: tp == NULL", __func__)); 3851 3852 bzero(&cap, sizeof(cap)); 3853 tcp_mss_update(tp, offer, -1, &metrics, &cap); 3854 3855 mss = tp->t_maxseg; 3856 inp = tp->t_inpcb; 3857 3858 /* 3859 * If there's a pipesize, change the socket buffer to that size, 3860 * don't change if sb_hiwat is different than default (then it 3861 * has been changed on purpose with setsockopt). 3862 * Make the socket buffers an integral number of mss units; 3863 * if the mss is larger than the socket buffer, decrease the mss. 3864 */ 3865 so = inp->inp_socket; 3866 SOCKBUF_LOCK(&so->so_snd); 3867 if ((so->so_snd.sb_hiwat == V_tcp_sendspace) && metrics.rmx_sendpipe) 3868 bufsize = metrics.rmx_sendpipe; 3869 else 3870 bufsize = so->so_snd.sb_hiwat; 3871 if (bufsize < mss) 3872 mss = bufsize; 3873 else { 3874 bufsize = roundup(bufsize, mss); 3875 if (bufsize > sb_max) 3876 bufsize = sb_max; 3877 if (bufsize > so->so_snd.sb_hiwat) 3878 (void)sbreserve_locked(&so->so_snd, bufsize, so, NULL); 3879 } 3880 SOCKBUF_UNLOCK(&so->so_snd); 3881 /* 3882 * Sanity check: make sure that maxseg will be large 3883 * enough to allow some data on segments even if the 3884 * all the option space is used (40bytes). Otherwise 3885 * funny things may happen in tcp_output. 3886 * 3887 * XXXGL: shouldn't we reserve space for IP/IPv6 options? 3888 */ 3889 tp->t_maxseg = max(mss, 64); 3890 3891 SOCKBUF_LOCK(&so->so_rcv); 3892 if ((so->so_rcv.sb_hiwat == V_tcp_recvspace) && metrics.rmx_recvpipe) 3893 bufsize = metrics.rmx_recvpipe; 3894 else 3895 bufsize = so->so_rcv.sb_hiwat; 3896 if (bufsize > mss) { 3897 bufsize = roundup(bufsize, mss); 3898 if (bufsize > sb_max) 3899 bufsize = sb_max; 3900 if (bufsize > so->so_rcv.sb_hiwat) 3901 (void)sbreserve_locked(&so->so_rcv, bufsize, so, NULL); 3902 } 3903 SOCKBUF_UNLOCK(&so->so_rcv); 3904 3905 /* Check the interface for TSO capabilities. */ 3906 if (cap.ifcap & CSUM_TSO) { 3907 tp->t_flags |= TF_TSO; 3908 tp->t_tsomax = cap.tsomax; 3909 tp->t_tsomaxsegcount = cap.tsomaxsegcount; 3910 tp->t_tsomaxsegsize = cap.tsomaxsegsize; 3911 } 3912 } 3913 3914 /* 3915 * Determine the MSS option to send on an outgoing SYN. 3916 */ 3917 int 3918 tcp_mssopt(struct in_conninfo *inc) 3919 { 3920 int mss = 0; 3921 uint32_t thcmtu = 0; 3922 uint32_t maxmtu = 0; 3923 size_t min_protoh; 3924 3925 KASSERT(inc != NULL, ("tcp_mssopt with NULL in_conninfo pointer")); 3926 3927 #ifdef INET6 3928 if (inc->inc_flags & INC_ISIPV6) { 3929 mss = V_tcp_v6mssdflt; 3930 maxmtu = tcp_maxmtu6(inc, NULL); 3931 min_protoh = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 3932 } 3933 #endif 3934 #if defined(INET) && defined(INET6) 3935 else 3936 #endif 3937 #ifdef INET 3938 { 3939 mss = V_tcp_mssdflt; 3940 maxmtu = tcp_maxmtu(inc, NULL); 3941 min_protoh = sizeof(struct tcpiphdr); 3942 } 3943 #endif 3944 #if defined(INET6) || defined(INET) 3945 thcmtu = tcp_hc_getmtu(inc); /* IPv4 and IPv6 */ 3946 #endif 3947 3948 if (maxmtu && thcmtu) 3949 mss = min(maxmtu, thcmtu) - min_protoh; 3950 else if (maxmtu || thcmtu) 3951 mss = max(maxmtu, thcmtu) - min_protoh; 3952 3953 return (mss); 3954 } 3955 3956 void 3957 tcp_do_prr_ack(struct tcpcb *tp, struct tcphdr *th, struct tcpopt *to) 3958 { 3959 int snd_cnt = 0, limit = 0, del_data = 0, pipe = 0; 3960 int maxseg = tcp_maxseg(tp); 3961 3962 INP_WLOCK_ASSERT(tp->t_inpcb); 3963 3964 /* 3965 * Compute the amount of data that this ACK is indicating 3966 * (del_data) and an estimate of how many bytes are in the 3967 * network. 3968 */ 3969 if (((tp->t_flags & TF_SACK_PERMIT) && 3970 (to->to_flags & TOF_SACK)) || 3971 (IN_CONGRECOVERY(tp->t_flags) && 3972 !IN_FASTRECOVERY(tp->t_flags))) { 3973 del_data = tp->sackhint.delivered_data; 3974 if (V_tcp_do_newsack) 3975 pipe = tcp_compute_pipe(tp); 3976 else 3977 pipe = (tp->snd_nxt - tp->snd_fack) + 3978 tp->sackhint.sack_bytes_rexmit; 3979 } else { 3980 if (tp->sackhint.prr_delivered < (tcprexmtthresh * maxseg + 3981 tp->snd_recover - tp->snd_una)) 3982 del_data = maxseg; 3983 pipe = imax(0, tp->snd_max - tp->snd_una - 3984 imin(INT_MAX / 65536, tp->t_dupacks) * maxseg); 3985 } 3986 tp->sackhint.prr_delivered += del_data; 3987 /* 3988 * Proportional Rate Reduction 3989 */ 3990 if (pipe >= tp->snd_ssthresh) { 3991 if (tp->sackhint.recover_fs == 0) 3992 tp->sackhint.recover_fs = 3993 imax(1, tp->snd_nxt - tp->snd_una); 3994 snd_cnt = howmany((long)tp->sackhint.prr_delivered * 3995 tp->snd_ssthresh, tp->sackhint.recover_fs) - 3996 tp->sackhint.prr_out; 3997 } else { 3998 if (V_tcp_do_prr_conservative || (del_data == 0)) 3999 limit = tp->sackhint.prr_delivered - 4000 tp->sackhint.prr_out; 4001 else 4002 limit = imax(tp->sackhint.prr_delivered - 4003 tp->sackhint.prr_out, del_data) + 4004 maxseg; 4005 snd_cnt = imin((tp->snd_ssthresh - pipe), limit); 4006 } 4007 snd_cnt = imax(snd_cnt, 0) / maxseg; 4008 /* 4009 * Send snd_cnt new data into the network in response to this ack. 4010 * If there is going to be a SACK retransmission, adjust snd_cwnd 4011 * accordingly. 4012 */ 4013 if (IN_FASTRECOVERY(tp->t_flags)) { 4014 if ((tp->t_flags & TF_SACK_PERMIT) && 4015 (to->to_flags & TOF_SACK)) { 4016 tp->snd_cwnd = tp->snd_nxt - tp->snd_recover + 4017 tp->sackhint.sack_bytes_rexmit + 4018 (snd_cnt * maxseg); 4019 } else { 4020 tp->snd_cwnd = (tp->snd_max - tp->snd_una) + 4021 (snd_cnt * maxseg); 4022 } 4023 } else if (IN_CONGRECOVERY(tp->t_flags)) 4024 tp->snd_cwnd = pipe - del_data + (snd_cnt * maxseg); 4025 tp->snd_cwnd = imax(maxseg, tp->snd_cwnd); 4026 } 4027 4028 /* 4029 * On a partial ack arrives, force the retransmission of the 4030 * next unacknowledged segment. Do not clear tp->t_dupacks. 4031 * By setting snd_nxt to ti_ack, this forces retransmission timer to 4032 * be started again. 4033 */ 4034 void 4035 tcp_newreno_partial_ack(struct tcpcb *tp, struct tcphdr *th) 4036 { 4037 tcp_seq onxt = tp->snd_nxt; 4038 uint32_t ocwnd = tp->snd_cwnd; 4039 u_int maxseg = tcp_maxseg(tp); 4040 4041 INP_WLOCK_ASSERT(tp->t_inpcb); 4042 4043 tcp_timer_activate(tp, TT_REXMT, 0); 4044 tp->t_rtttime = 0; 4045 tp->snd_nxt = th->th_ack; 4046 /* 4047 * Set snd_cwnd to one segment beyond acknowledged offset. 4048 * (tp->snd_una has not yet been updated when this function is called.) 4049 */ 4050 tp->snd_cwnd = maxseg + BYTES_THIS_ACK(tp, th); 4051 tp->t_flags |= TF_ACKNOW; 4052 (void) tcp_output(tp); 4053 tp->snd_cwnd = ocwnd; 4054 if (SEQ_GT(onxt, tp->snd_nxt)) 4055 tp->snd_nxt = onxt; 4056 /* 4057 * Partial window deflation. Relies on fact that tp->snd_una 4058 * not updated yet. 4059 */ 4060 if (tp->snd_cwnd > BYTES_THIS_ACK(tp, th)) 4061 tp->snd_cwnd -= BYTES_THIS_ACK(tp, th); 4062 else 4063 tp->snd_cwnd = 0; 4064 tp->snd_cwnd += maxseg; 4065 } 4066 4067 int 4068 tcp_compute_pipe(struct tcpcb *tp) 4069 { 4070 return (tp->snd_max - tp->snd_una + 4071 tp->sackhint.sack_bytes_rexmit - 4072 tp->sackhint.sacked_bytes); 4073 } 4074 4075 uint32_t 4076 tcp_compute_initwnd(uint32_t maxseg) 4077 { 4078 /* 4079 * Calculate the Initial Window, also used as Restart Window 4080 * 4081 * RFC5681 Section 3.1 specifies the default conservative values. 4082 * RFC3390 specifies slightly more aggressive values. 4083 * RFC6928 increases it to ten segments. 4084 * Support for user specified value for initial flight size. 4085 */ 4086 if (V_tcp_initcwnd_segments) 4087 return min(V_tcp_initcwnd_segments * maxseg, 4088 max(2 * maxseg, V_tcp_initcwnd_segments * 1460)); 4089 else if (V_tcp_do_rfc3390) 4090 return min(4 * maxseg, max(2 * maxseg, 4380)); 4091 else { 4092 /* Per RFC5681 Section 3.1 */ 4093 if (maxseg > 2190) 4094 return (2 * maxseg); 4095 else if (maxseg > 1095) 4096 return (3 * maxseg); 4097 else 4098 return (4 * maxseg); 4099 } 4100 } 4101