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 #include <netinet/tcp_debug.h> 121 #ifdef TCP_OFFLOAD 122 #include <netinet/tcp_offload.h> 123 #endif 124 #include <netinet/tcp_ecn.h> 125 #include <netinet/udp.h> 126 127 #include <netipsec/ipsec_support.h> 128 129 #include <machine/in_cksum.h> 130 131 #include <security/mac/mac_framework.h> 132 133 const int tcprexmtthresh = 3; 134 135 VNET_DEFINE(int, tcp_log_in_vain) = 0; 136 SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_in_vain, CTLFLAG_VNET | CTLFLAG_RW, 137 &VNET_NAME(tcp_log_in_vain), 0, 138 "Log all incoming TCP segments to closed ports"); 139 140 VNET_DEFINE(int, blackhole) = 0; 141 #define V_blackhole VNET(blackhole) 142 SYSCTL_INT(_net_inet_tcp, OID_AUTO, blackhole, CTLFLAG_VNET | CTLFLAG_RW, 143 &VNET_NAME(blackhole), 0, 144 "Do not send RST on segments to closed ports"); 145 146 VNET_DEFINE(bool, blackhole_local) = false; 147 #define V_blackhole_local VNET(blackhole_local) 148 SYSCTL_BOOL(_net_inet_tcp, OID_AUTO, blackhole_local, CTLFLAG_VNET | 149 CTLFLAG_RW, &VNET_NAME(blackhole_local), false, 150 "Enforce net.inet.tcp.blackhole for locally originated packets"); 151 152 VNET_DEFINE(int, tcp_delack_enabled) = 1; 153 SYSCTL_INT(_net_inet_tcp, OID_AUTO, delayed_ack, CTLFLAG_VNET | CTLFLAG_RW, 154 &VNET_NAME(tcp_delack_enabled), 0, 155 "Delay ACK to try and piggyback it onto a data packet"); 156 157 VNET_DEFINE(int, drop_synfin) = 0; 158 SYSCTL_INT(_net_inet_tcp, OID_AUTO, drop_synfin, CTLFLAG_VNET | CTLFLAG_RW, 159 &VNET_NAME(drop_synfin), 0, 160 "Drop TCP packets with SYN+FIN set"); 161 162 VNET_DEFINE(int, tcp_do_prr_conservative) = 0; 163 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_prr_conservative, CTLFLAG_VNET | CTLFLAG_RW, 164 &VNET_NAME(tcp_do_prr_conservative), 0, 165 "Do conservative Proportional Rate Reduction"); 166 167 VNET_DEFINE(int, tcp_do_prr) = 1; 168 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_prr, CTLFLAG_VNET | CTLFLAG_RW, 169 &VNET_NAME(tcp_do_prr), 1, 170 "Enable Proportional Rate Reduction per RFC 6937"); 171 172 VNET_DEFINE(int, tcp_do_lrd) = 0; 173 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_lrd, CTLFLAG_VNET | CTLFLAG_RW, 174 &VNET_NAME(tcp_do_lrd), 1, 175 "Perform Lost Retransmission Detection"); 176 177 VNET_DEFINE(int, tcp_do_newcwv) = 0; 178 SYSCTL_INT(_net_inet_tcp, OID_AUTO, newcwv, CTLFLAG_VNET | CTLFLAG_RW, 179 &VNET_NAME(tcp_do_newcwv), 0, 180 "Enable New Congestion Window Validation per RFC7661"); 181 182 VNET_DEFINE(int, tcp_do_rfc3042) = 1; 183 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3042, CTLFLAG_VNET | CTLFLAG_RW, 184 &VNET_NAME(tcp_do_rfc3042), 0, 185 "Enable RFC 3042 (Limited Transmit)"); 186 187 VNET_DEFINE(int, tcp_do_rfc3390) = 1; 188 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3390, CTLFLAG_VNET | CTLFLAG_RW, 189 &VNET_NAME(tcp_do_rfc3390), 0, 190 "Enable RFC 3390 (Increasing TCP's Initial Congestion Window)"); 191 192 VNET_DEFINE(int, tcp_initcwnd_segments) = 10; 193 SYSCTL_INT(_net_inet_tcp, OID_AUTO, initcwnd_segments, 194 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(tcp_initcwnd_segments), 0, 195 "Slow-start flight size (initial congestion window) in number of segments"); 196 197 VNET_DEFINE(int, tcp_do_rfc3465) = 1; 198 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3465, CTLFLAG_VNET | CTLFLAG_RW, 199 &VNET_NAME(tcp_do_rfc3465), 0, 200 "Enable RFC 3465 (Appropriate Byte Counting)"); 201 202 VNET_DEFINE(int, tcp_abc_l_var) = 2; 203 SYSCTL_INT(_net_inet_tcp, OID_AUTO, abc_l_var, CTLFLAG_VNET | CTLFLAG_RW, 204 &VNET_NAME(tcp_abc_l_var), 2, 205 "Cap the max cwnd increment during slow-start to this number of segments"); 206 207 VNET_DEFINE(int, tcp_insecure_syn) = 0; 208 SYSCTL_INT(_net_inet_tcp, OID_AUTO, insecure_syn, CTLFLAG_VNET | CTLFLAG_RW, 209 &VNET_NAME(tcp_insecure_syn), 0, 210 "Follow RFC793 instead of RFC5961 criteria for accepting SYN packets"); 211 212 VNET_DEFINE(int, tcp_insecure_rst) = 0; 213 SYSCTL_INT(_net_inet_tcp, OID_AUTO, insecure_rst, CTLFLAG_VNET | CTLFLAG_RW, 214 &VNET_NAME(tcp_insecure_rst), 0, 215 "Follow RFC793 instead of RFC5961 criteria for accepting RST packets"); 216 217 VNET_DEFINE(int, tcp_recvspace) = 1024*64; 218 #define V_tcp_recvspace VNET(tcp_recvspace) 219 SYSCTL_INT(_net_inet_tcp, TCPCTL_RECVSPACE, recvspace, CTLFLAG_VNET | CTLFLAG_RW, 220 &VNET_NAME(tcp_recvspace), 0, "Initial receive socket buffer size"); 221 222 VNET_DEFINE(int, tcp_do_autorcvbuf) = 1; 223 SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_auto, CTLFLAG_VNET | CTLFLAG_RW, 224 &VNET_NAME(tcp_do_autorcvbuf), 0, 225 "Enable automatic receive buffer sizing"); 226 227 VNET_DEFINE(int, tcp_autorcvbuf_max) = 2*1024*1024; 228 SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_max, CTLFLAG_VNET | CTLFLAG_RW, 229 &VNET_NAME(tcp_autorcvbuf_max), 0, 230 "Max size of automatic receive buffer"); 231 232 VNET_DEFINE(struct inpcbinfo, tcbinfo); 233 234 /* 235 * TCP statistics are stored in an array of counter(9)s, which size matches 236 * size of struct tcpstat. TCP running connection count is a regular array. 237 */ 238 VNET_PCPUSTAT_DEFINE(struct tcpstat, tcpstat); 239 SYSCTL_VNET_PCPUSTAT(_net_inet_tcp, TCPCTL_STATS, stats, struct tcpstat, 240 tcpstat, "TCP statistics (struct tcpstat, netinet/tcp_var.h)"); 241 VNET_DEFINE(counter_u64_t, tcps_states[TCP_NSTATES]); 242 SYSCTL_COUNTER_U64_ARRAY(_net_inet_tcp, TCPCTL_STATES, states, CTLFLAG_RD | 243 CTLFLAG_VNET, &VNET_NAME(tcps_states)[0], TCP_NSTATES, 244 "TCP connection counts by TCP state"); 245 246 /* 247 * Kernel module interface for updating tcpstat. The first argument is an index 248 * into tcpstat treated as an array. 249 */ 250 void 251 kmod_tcpstat_add(int statnum, int val) 252 { 253 254 counter_u64_add(VNET(tcpstat)[statnum], val); 255 } 256 257 /* 258 * Make sure that we only start a SACK loss recovery when 259 * receiving a duplicate ACK with a SACK block, and also 260 * complete SACK loss recovery in case the other end 261 * reneges. 262 */ 263 static bool inline 264 tcp_is_sack_recovery(struct tcpcb *tp, struct tcpopt *to) 265 { 266 return ((tp->t_flags & TF_SACK_PERMIT) && 267 ((to->to_flags & TOF_SACK) || 268 (!TAILQ_EMPTY(&tp->snd_holes)))); 269 } 270 271 #ifdef TCP_HHOOK 272 /* 273 * Wrapper for the TCP established input helper hook. 274 */ 275 void 276 hhook_run_tcp_est_in(struct tcpcb *tp, struct tcphdr *th, struct tcpopt *to) 277 { 278 struct tcp_hhook_data hhook_data; 279 280 if (V_tcp_hhh[HHOOK_TCP_EST_IN]->hhh_nhooks > 0) { 281 hhook_data.tp = tp; 282 hhook_data.th = th; 283 hhook_data.to = to; 284 285 hhook_run_hooks(V_tcp_hhh[HHOOK_TCP_EST_IN], &hhook_data, 286 tp->osd); 287 } 288 } 289 #endif 290 291 /* 292 * CC wrapper hook functions 293 */ 294 void 295 cc_ack_received(struct tcpcb *tp, struct tcphdr *th, uint16_t nsegs, 296 uint16_t type) 297 { 298 #ifdef STATS 299 int32_t gput; 300 #endif 301 302 INP_WLOCK_ASSERT(tp->t_inpcb); 303 304 tp->ccv->nsegs = nsegs; 305 tp->ccv->bytes_this_ack = BYTES_THIS_ACK(tp, th); 306 if ((!V_tcp_do_newcwv && (tp->snd_cwnd <= tp->snd_wnd)) || 307 (V_tcp_do_newcwv && (tp->snd_cwnd <= tp->snd_wnd) && 308 (tp->snd_cwnd < (tcp_compute_pipe(tp) * 2)))) 309 tp->ccv->flags |= CCF_CWND_LIMITED; 310 else 311 tp->ccv->flags &= ~CCF_CWND_LIMITED; 312 313 if (type == CC_ACK) { 314 #ifdef STATS 315 stats_voi_update_abs_s32(tp->t_stats, VOI_TCP_CALCFRWINDIFF, 316 ((int32_t)tp->snd_cwnd) - tp->snd_wnd); 317 if (!IN_RECOVERY(tp->t_flags)) 318 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_ACKLEN, 319 tp->ccv->bytes_this_ack / (tcp_maxseg(tp) * nsegs)); 320 if ((tp->t_flags & TF_GPUTINPROG) && 321 SEQ_GEQ(th->th_ack, tp->gput_ack)) { 322 /* 323 * Compute goodput in bits per millisecond. 324 */ 325 gput = (((int64_t)SEQ_SUB(th->th_ack, tp->gput_seq)) << 3) / 326 max(1, tcp_ts_getticks() - tp->gput_ts); 327 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_GPUT, 328 gput); 329 /* 330 * XXXLAS: This is a temporary hack, and should be 331 * chained off VOI_TCP_GPUT when stats(9) grows an API 332 * to deal with chained VOIs. 333 */ 334 if (tp->t_stats_gput_prev > 0) 335 stats_voi_update_abs_s32(tp->t_stats, 336 VOI_TCP_GPUT_ND, 337 ((gput - tp->t_stats_gput_prev) * 100) / 338 tp->t_stats_gput_prev); 339 tp->t_flags &= ~TF_GPUTINPROG; 340 tp->t_stats_gput_prev = gput; 341 } 342 #endif /* STATS */ 343 if (tp->snd_cwnd > tp->snd_ssthresh) { 344 tp->t_bytes_acked += tp->ccv->bytes_this_ack; 345 if (tp->t_bytes_acked >= tp->snd_cwnd) { 346 tp->t_bytes_acked -= tp->snd_cwnd; 347 tp->ccv->flags |= CCF_ABC_SENTAWND; 348 } 349 } else { 350 tp->ccv->flags &= ~CCF_ABC_SENTAWND; 351 tp->t_bytes_acked = 0; 352 } 353 } 354 355 if (CC_ALGO(tp)->ack_received != NULL) { 356 /* XXXLAS: Find a way to live without this */ 357 tp->ccv->curack = th->th_ack; 358 CC_ALGO(tp)->ack_received(tp->ccv, type); 359 } 360 #ifdef STATS 361 stats_voi_update_abs_ulong(tp->t_stats, VOI_TCP_LCWIN, tp->snd_cwnd); 362 #endif 363 } 364 365 void 366 cc_conn_init(struct tcpcb *tp) 367 { 368 struct hc_metrics_lite metrics; 369 struct inpcb *inp = tp->t_inpcb; 370 u_int maxseg; 371 int rtt; 372 373 INP_WLOCK_ASSERT(tp->t_inpcb); 374 375 tcp_hc_get(&inp->inp_inc, &metrics); 376 maxseg = tcp_maxseg(tp); 377 378 if (tp->t_srtt == 0 && (rtt = metrics.rmx_rtt)) { 379 tp->t_srtt = rtt; 380 tp->t_rttbest = tp->t_srtt + TCP_RTT_SCALE; 381 TCPSTAT_INC(tcps_usedrtt); 382 if (metrics.rmx_rttvar) { 383 tp->t_rttvar = metrics.rmx_rttvar; 384 TCPSTAT_INC(tcps_usedrttvar); 385 } else { 386 /* default variation is +- 1 rtt */ 387 tp->t_rttvar = 388 tp->t_srtt * TCP_RTTVAR_SCALE / TCP_RTT_SCALE; 389 } 390 TCPT_RANGESET(tp->t_rxtcur, 391 ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1, 392 tp->t_rttmin, TCPTV_REXMTMAX); 393 } 394 if (metrics.rmx_ssthresh) { 395 /* 396 * There's some sort of gateway or interface 397 * buffer limit on the path. Use this to set 398 * the slow start threshold, but set the 399 * threshold to no less than 2*mss. 400 */ 401 tp->snd_ssthresh = max(2 * maxseg, metrics.rmx_ssthresh); 402 TCPSTAT_INC(tcps_usedssthresh); 403 } 404 405 /* 406 * Set the initial slow-start flight size. 407 * 408 * If a SYN or SYN/ACK was lost and retransmitted, we have to 409 * reduce the initial CWND to one segment as congestion is likely 410 * requiring us to be cautious. 411 */ 412 if (tp->snd_cwnd == 1) 413 tp->snd_cwnd = maxseg; /* SYN(-ACK) lost */ 414 else 415 tp->snd_cwnd = tcp_compute_initwnd(maxseg); 416 417 if (CC_ALGO(tp)->conn_init != NULL) 418 CC_ALGO(tp)->conn_init(tp->ccv); 419 } 420 421 void inline 422 cc_cong_signal(struct tcpcb *tp, struct tcphdr *th, uint32_t type) 423 { 424 INP_WLOCK_ASSERT(tp->t_inpcb); 425 426 #ifdef STATS 427 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_CSIG, type); 428 #endif 429 430 switch(type) { 431 case CC_NDUPACK: 432 if (!IN_FASTRECOVERY(tp->t_flags)) { 433 tp->snd_recover = tp->snd_max; 434 if (tp->t_flags2 & TF2_ECN_PERMIT) 435 tp->t_flags2 |= TF2_ECN_SND_CWR; 436 } 437 break; 438 case CC_ECN: 439 if (!IN_CONGRECOVERY(tp->t_flags) || 440 /* 441 * Allow ECN reaction on ACK to CWR, if 442 * that data segment was also CE marked. 443 */ 444 SEQ_GEQ(th->th_ack, tp->snd_recover)) { 445 EXIT_CONGRECOVERY(tp->t_flags); 446 TCPSTAT_INC(tcps_ecn_rcwnd); 447 tp->snd_recover = tp->snd_max + 1; 448 if (tp->t_flags2 & TF2_ECN_PERMIT) 449 tp->t_flags2 |= TF2_ECN_SND_CWR; 450 } 451 break; 452 case CC_RTO: 453 tp->t_dupacks = 0; 454 tp->t_bytes_acked = 0; 455 EXIT_RECOVERY(tp->t_flags); 456 if (tp->t_flags2 & TF2_ECN_PERMIT) 457 tp->t_flags2 |= TF2_ECN_SND_CWR; 458 break; 459 case CC_RTO_ERR: 460 TCPSTAT_INC(tcps_sndrexmitbad); 461 /* RTO was unnecessary, so reset everything. */ 462 tp->snd_cwnd = tp->snd_cwnd_prev; 463 tp->snd_ssthresh = tp->snd_ssthresh_prev; 464 tp->snd_recover = tp->snd_recover_prev; 465 if (tp->t_flags & TF_WASFRECOVERY) 466 ENTER_FASTRECOVERY(tp->t_flags); 467 if (tp->t_flags & TF_WASCRECOVERY) 468 ENTER_CONGRECOVERY(tp->t_flags); 469 tp->snd_nxt = tp->snd_max; 470 tp->t_flags &= ~TF_PREVVALID; 471 tp->t_badrxtwin = 0; 472 break; 473 } 474 475 if (CC_ALGO(tp)->cong_signal != NULL) { 476 if (th != NULL) 477 tp->ccv->curack = th->th_ack; 478 CC_ALGO(tp)->cong_signal(tp->ccv, type); 479 } 480 } 481 482 void inline 483 cc_post_recovery(struct tcpcb *tp, struct tcphdr *th) 484 { 485 INP_WLOCK_ASSERT(tp->t_inpcb); 486 487 /* XXXLAS: KASSERT that we're in recovery? */ 488 489 if (CC_ALGO(tp)->post_recovery != NULL) { 490 tp->ccv->curack = th->th_ack; 491 CC_ALGO(tp)->post_recovery(tp->ccv); 492 } 493 /* XXXLAS: EXIT_RECOVERY ? */ 494 tp->t_bytes_acked = 0; 495 tp->sackhint.delivered_data = 0; 496 tp->sackhint.prr_out = 0; 497 } 498 499 /* 500 * Indicate whether this ack should be delayed. We can delay the ack if 501 * following conditions are met: 502 * - There is no delayed ack timer in progress. 503 * - Our last ack wasn't a 0-sized window. We never want to delay 504 * the ack that opens up a 0-sized window. 505 * - LRO wasn't used for this segment. We make sure by checking that the 506 * segment size is not larger than the MSS. 507 */ 508 #define DELAY_ACK(tp, tlen) \ 509 ((!tcp_timer_active(tp, TT_DELACK) && \ 510 (tp->t_flags & TF_RXWIN0SENT) == 0) && \ 511 (tlen <= tp->t_maxseg) && \ 512 (V_tcp_delack_enabled || (tp->t_flags & TF_NEEDSYN))) 513 514 void inline 515 cc_ecnpkt_handler_flags(struct tcpcb *tp, uint16_t flags, uint8_t iptos) 516 { 517 INP_WLOCK_ASSERT(tp->t_inpcb); 518 519 if (CC_ALGO(tp)->ecnpkt_handler != NULL) { 520 switch (iptos & IPTOS_ECN_MASK) { 521 case IPTOS_ECN_CE: 522 tp->ccv->flags |= CCF_IPHDR_CE; 523 break; 524 case IPTOS_ECN_ECT0: 525 /* FALLTHROUGH */ 526 case IPTOS_ECN_ECT1: 527 /* FALLTHROUGH */ 528 case IPTOS_ECN_NOTECT: 529 tp->ccv->flags &= ~CCF_IPHDR_CE; 530 break; 531 } 532 533 if (flags & TH_CWR) 534 tp->ccv->flags |= CCF_TCPHDR_CWR; 535 else 536 tp->ccv->flags &= ~CCF_TCPHDR_CWR; 537 538 CC_ALGO(tp)->ecnpkt_handler(tp->ccv); 539 540 if (tp->ccv->flags & CCF_ACKNOW) { 541 tcp_timer_activate(tp, TT_DELACK, tcp_delacktime); 542 tp->t_flags |= TF_ACKNOW; 543 } 544 } 545 } 546 547 void inline 548 cc_ecnpkt_handler(struct tcpcb *tp, struct tcphdr *th, uint8_t iptos) 549 { 550 cc_ecnpkt_handler_flags(tp, tcp_get_flags(th), iptos); 551 } 552 553 /* 554 * TCP input handling is split into multiple parts: 555 * tcp6_input is a thin wrapper around tcp_input for the extended 556 * ip6_protox[] call format in ip6_input 557 * tcp_input handles primary segment validation, inpcb lookup and 558 * SYN processing on listen sockets 559 * tcp_do_segment processes the ACK and text of the segment for 560 * establishing, established and closing connections 561 */ 562 #ifdef INET6 563 int 564 tcp6_input_with_port(struct mbuf **mp, int *offp, int proto, uint16_t port) 565 { 566 struct mbuf *m; 567 struct in6_ifaddr *ia6; 568 struct ip6_hdr *ip6; 569 570 m = *mp; 571 if (m->m_len < *offp + sizeof(struct tcphdr)) { 572 m = m_pullup(m, *offp + sizeof(struct tcphdr)); 573 if (m == NULL) { 574 *mp = m; 575 TCPSTAT_INC(tcps_rcvshort); 576 return (IPPROTO_DONE); 577 } 578 } 579 580 /* 581 * draft-itojun-ipv6-tcp-to-anycast 582 * better place to put this in? 583 */ 584 ip6 = mtod(m, struct ip6_hdr *); 585 ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */, false); 586 if (ia6 && (ia6->ia6_flags & IN6_IFF_ANYCAST)) { 587 icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR, 588 (caddr_t)&ip6->ip6_dst - (caddr_t)ip6); 589 *mp = NULL; 590 return (IPPROTO_DONE); 591 } 592 593 *mp = m; 594 return (tcp_input_with_port(mp, offp, proto, port)); 595 } 596 597 int 598 tcp6_input(struct mbuf **mp, int *offp, int proto) 599 { 600 601 return(tcp6_input_with_port(mp, offp, proto, 0)); 602 } 603 #endif /* INET6 */ 604 605 int 606 tcp_input_with_port(struct mbuf **mp, int *offp, int proto, uint16_t port) 607 { 608 struct mbuf *m = *mp; 609 struct tcphdr *th = NULL; 610 struct ip *ip = NULL; 611 struct inpcb *inp = NULL; 612 struct tcpcb *tp = NULL; 613 struct socket *so = NULL; 614 u_char *optp = NULL; 615 int off0; 616 int optlen = 0; 617 #ifdef INET 618 int len; 619 uint8_t ipttl; 620 #endif 621 int tlen = 0, off; 622 int drop_hdrlen; 623 int thflags; 624 int rstreason = 0; /* For badport_bandlim accounting purposes */ 625 int lookupflag; 626 uint8_t iptos; 627 struct m_tag *fwd_tag = NULL; 628 #ifdef INET6 629 struct ip6_hdr *ip6 = NULL; 630 int isipv6; 631 #else 632 const void *ip6 = NULL; 633 #endif /* INET6 */ 634 struct tcpopt to; /* options in this segment */ 635 char *s = NULL; /* address and port logging */ 636 #ifdef TCPDEBUG 637 /* 638 * The size of tcp_saveipgen must be the size of the max ip header, 639 * now IPv6. 640 */ 641 u_char tcp_saveipgen[IP6_HDR_LEN]; 642 struct tcphdr tcp_savetcp; 643 short ostate = 0; 644 #endif 645 646 NET_EPOCH_ASSERT(); 647 648 #ifdef INET6 649 isipv6 = (mtod(m, struct ip *)->ip_v == 6) ? 1 : 0; 650 #endif 651 652 off0 = *offp; 653 m = *mp; 654 *mp = NULL; 655 to.to_flags = 0; 656 TCPSTAT_INC(tcps_rcvtotal); 657 658 #ifdef INET6 659 if (isipv6) { 660 ip6 = mtod(m, struct ip6_hdr *); 661 th = (struct tcphdr *)((caddr_t)ip6 + off0); 662 tlen = sizeof(*ip6) + ntohs(ip6->ip6_plen) - off0; 663 if (port) 664 goto skip6_csum; 665 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID_IPV6) { 666 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 667 th->th_sum = m->m_pkthdr.csum_data; 668 else 669 th->th_sum = in6_cksum_pseudo(ip6, tlen, 670 IPPROTO_TCP, m->m_pkthdr.csum_data); 671 th->th_sum ^= 0xffff; 672 } else 673 th->th_sum = in6_cksum(m, IPPROTO_TCP, off0, tlen); 674 if (th->th_sum) { 675 TCPSTAT_INC(tcps_rcvbadsum); 676 goto drop; 677 } 678 skip6_csum: 679 /* 680 * Be proactive about unspecified IPv6 address in source. 681 * As we use all-zero to indicate unbounded/unconnected pcb, 682 * unspecified IPv6 address can be used to confuse us. 683 * 684 * Note that packets with unspecified IPv6 destination is 685 * already dropped in ip6_input. 686 */ 687 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 688 /* XXX stat */ 689 goto drop; 690 } 691 iptos = IPV6_TRAFFIC_CLASS(ip6); 692 } 693 #endif 694 #if defined(INET) && defined(INET6) 695 else 696 #endif 697 #ifdef INET 698 { 699 /* 700 * Get IP and TCP header together in first mbuf. 701 * Note: IP leaves IP header in first mbuf. 702 */ 703 if (off0 > sizeof (struct ip)) { 704 ip_stripoptions(m); 705 off0 = sizeof(struct ip); 706 } 707 if (m->m_len < sizeof (struct tcpiphdr)) { 708 if ((m = m_pullup(m, sizeof (struct tcpiphdr))) 709 == NULL) { 710 TCPSTAT_INC(tcps_rcvshort); 711 return (IPPROTO_DONE); 712 } 713 } 714 ip = mtod(m, struct ip *); 715 th = (struct tcphdr *)((caddr_t)ip + off0); 716 tlen = ntohs(ip->ip_len) - off0; 717 718 iptos = ip->ip_tos; 719 if (port) 720 goto skip_csum; 721 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) { 722 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 723 th->th_sum = m->m_pkthdr.csum_data; 724 else 725 th->th_sum = in_pseudo(ip->ip_src.s_addr, 726 ip->ip_dst.s_addr, 727 htonl(m->m_pkthdr.csum_data + tlen + 728 IPPROTO_TCP)); 729 th->th_sum ^= 0xffff; 730 } else { 731 struct ipovly *ipov = (struct ipovly *)ip; 732 733 /* 734 * Checksum extended TCP header and data. 735 */ 736 len = off0 + tlen; 737 ipttl = ip->ip_ttl; 738 bzero(ipov->ih_x1, sizeof(ipov->ih_x1)); 739 ipov->ih_len = htons(tlen); 740 th->th_sum = in_cksum(m, len); 741 /* Reset length for SDT probes. */ 742 ip->ip_len = htons(len); 743 /* Reset TOS bits */ 744 ip->ip_tos = iptos; 745 /* Re-initialization for later version check */ 746 ip->ip_ttl = ipttl; 747 ip->ip_v = IPVERSION; 748 ip->ip_hl = off0 >> 2; 749 } 750 skip_csum: 751 if (th->th_sum && (port == 0)) { 752 TCPSTAT_INC(tcps_rcvbadsum); 753 goto drop; 754 } 755 } 756 #endif /* INET */ 757 758 /* 759 * Check that TCP offset makes sense, 760 * pull out TCP options and adjust length. XXX 761 */ 762 off = th->th_off << 2; 763 if (off < sizeof (struct tcphdr) || off > tlen) { 764 TCPSTAT_INC(tcps_rcvbadoff); 765 goto drop; 766 } 767 tlen -= off; /* tlen is used instead of ti->ti_len */ 768 if (off > sizeof (struct tcphdr)) { 769 #ifdef INET6 770 if (isipv6) { 771 if (m->m_len < off0 + off) { 772 m = m_pullup(m, off0 + off); 773 if (m == NULL) { 774 TCPSTAT_INC(tcps_rcvshort); 775 return (IPPROTO_DONE); 776 } 777 } 778 ip6 = mtod(m, struct ip6_hdr *); 779 th = (struct tcphdr *)((caddr_t)ip6 + off0); 780 } 781 #endif 782 #if defined(INET) && defined(INET6) 783 else 784 #endif 785 #ifdef INET 786 { 787 if (m->m_len < sizeof(struct ip) + off) { 788 if ((m = m_pullup(m, sizeof (struct ip) + off)) 789 == NULL) { 790 TCPSTAT_INC(tcps_rcvshort); 791 return (IPPROTO_DONE); 792 } 793 ip = mtod(m, struct ip *); 794 th = (struct tcphdr *)((caddr_t)ip + off0); 795 } 796 } 797 #endif 798 optlen = off - sizeof (struct tcphdr); 799 optp = (u_char *)(th + 1); 800 } 801 thflags = tcp_get_flags(th); 802 803 /* 804 * Convert TCP protocol specific fields to host format. 805 */ 806 tcp_fields_to_host(th); 807 808 /* 809 * Delay dropping TCP, IP headers, IPv6 ext headers, and TCP options. 810 */ 811 drop_hdrlen = off0 + off; 812 813 /* 814 * Grab info from PACKET_TAG_IPFORWARD tag prepended to the chain. 815 */ 816 if ( 817 #ifdef INET6 818 (isipv6 && (m->m_flags & M_IP6_NEXTHOP)) 819 #ifdef INET 820 || (!isipv6 && (m->m_flags & M_IP_NEXTHOP)) 821 #endif 822 #endif 823 #if defined(INET) && !defined(INET6) 824 (m->m_flags & M_IP_NEXTHOP) 825 #endif 826 ) 827 fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL); 828 829 /* 830 * For initial SYN packets we don't need write lock on matching 831 * PCB, be it a listening one or a synchronized one. The packet 832 * shall not modify its state. 833 */ 834 lookupflag = INPLOOKUP_WILDCARD | 835 ((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, lookupflag, m->m_pkthdr.rcvif); 860 } 861 } else if (isipv6) { 862 inp = in6_pcblookup_mbuf(&V_tcbinfo, &ip6->ip6_src, 863 th->th_sport, &ip6->ip6_dst, th->th_dport, lookupflag, 864 m->m_pkthdr.rcvif, m); 865 } 866 #endif /* INET6 */ 867 #if defined(INET6) && defined(INET) 868 else 869 #endif 870 #ifdef INET 871 if (fwd_tag != NULL) { 872 struct sockaddr_in *next_hop; 873 874 next_hop = (struct sockaddr_in *)(fwd_tag+1); 875 /* 876 * Transparently forwarded. Pretend to be the destination. 877 * already got one like this? 878 */ 879 inp = in_pcblookup_mbuf(&V_tcbinfo, ip->ip_src, th->th_sport, 880 ip->ip_dst, th->th_dport, lookupflag, m->m_pkthdr.rcvif, m); 881 if (!inp) { 882 /* 883 * It's new. Try to find the ambushing socket. 884 * Because we've rewritten the destination address, 885 * any hardware-generated hash is ignored. 886 */ 887 inp = in_pcblookup(&V_tcbinfo, ip->ip_src, 888 th->th_sport, next_hop->sin_addr, 889 next_hop->sin_port ? ntohs(next_hop->sin_port) : 890 th->th_dport, lookupflag, m->m_pkthdr.rcvif); 891 } 892 } else 893 inp = in_pcblookup_mbuf(&V_tcbinfo, ip->ip_src, 894 th->th_sport, ip->ip_dst, th->th_dport, lookupflag, 895 m->m_pkthdr.rcvif, m); 896 #endif /* INET */ 897 898 /* 899 * If the INPCB does not exist then all data in the incoming 900 * segment is discarded and an appropriate RST is sent back. 901 * XXX MRT Send RST using which routing table? 902 */ 903 if (inp == NULL) { 904 if (rstreason != 0) { 905 /* We came here after second (safety) lookup. */ 906 MPASS((lookupflag & INPLOOKUP_WILDCARD) == 0); 907 goto dropwithreset; 908 } 909 /* 910 * Log communication attempts to ports that are not 911 * in use. 912 */ 913 if ((V_tcp_log_in_vain == 1 && (thflags & TH_SYN)) || 914 V_tcp_log_in_vain == 2) { 915 if ((s = tcp_log_vain(NULL, th, (void *)ip, ip6))) 916 log(LOG_INFO, "%s; %s: Connection attempt " 917 "to closed port\n", s, __func__); 918 } 919 /* 920 * When blackholing do not respond with a RST but 921 * completely ignore the segment and drop it. 922 */ 923 if (((V_blackhole == 1 && (thflags & TH_SYN)) || 924 V_blackhole == 2) && (V_blackhole_local || ( 925 #ifdef INET6 926 isipv6 ? !in6_localaddr(&ip6->ip6_src) : 927 #endif 928 #ifdef INET 929 !in_localip(ip->ip_src) 930 #else 931 true 932 #endif 933 ))) 934 goto dropunlock; 935 936 rstreason = BANDLIM_RST_CLOSEDPORT; 937 goto dropwithreset; 938 } 939 INP_LOCK_ASSERT(inp); 940 /* 941 * While waiting for inp lock during the lookup, another thread 942 * can have dropped the inpcb, in which case we need to loop back 943 * and try to find a new inpcb to deliver to. 944 */ 945 if (inp->inp_flags & INP_DROPPED) { 946 INP_UNLOCK(inp); 947 inp = NULL; 948 goto findpcb; 949 } 950 if ((inp->inp_flowtype == M_HASHTYPE_NONE) && 951 (M_HASHTYPE_GET(m) != M_HASHTYPE_NONE) && 952 ((inp->inp_socket == NULL) || !SOLISTENING(inp->inp_socket))) { 953 inp->inp_flowid = m->m_pkthdr.flowid; 954 inp->inp_flowtype = M_HASHTYPE_GET(m); 955 } 956 #if defined(IPSEC) || defined(IPSEC_SUPPORT) 957 #ifdef INET6 958 if (isipv6 && IPSEC_ENABLED(ipv6) && 959 IPSEC_CHECK_POLICY(ipv6, m, inp) != 0) { 960 goto dropunlock; 961 } 962 #ifdef INET 963 else 964 #endif 965 #endif /* INET6 */ 966 #ifdef INET 967 if (IPSEC_ENABLED(ipv4) && 968 IPSEC_CHECK_POLICY(ipv4, m, inp) != 0) { 969 goto dropunlock; 970 } 971 #endif /* INET */ 972 #endif /* IPSEC */ 973 974 /* 975 * Check the minimum TTL for socket. 976 */ 977 if (inp->inp_ip_minttl != 0) { 978 #ifdef INET6 979 if (isipv6) { 980 if (inp->inp_ip_minttl > ip6->ip6_hlim) 981 goto dropunlock; 982 } else 983 #endif 984 if (inp->inp_ip_minttl > ip->ip_ttl) 985 goto dropunlock; 986 } 987 988 tp = intotcpcb(inp); 989 switch (tp->t_state) { 990 case TCPS_TIME_WAIT: 991 /* 992 * A previous connection in TIMEWAIT state is supposed to catch 993 * stray or duplicate segments arriving late. If this segment 994 * was a legitimate new connection attempt, the old INPCB gets 995 * removed and we can try again to find a listening socket. 996 */ 997 tcp_dooptions(&to, optp, optlen, 998 (thflags & TH_SYN) ? TO_SYN : 0); 999 /* 1000 * tcp_twcheck unlocks the inp always, and frees the m if fails. 1001 */ 1002 if (tcp_twcheck(inp, &to, th, m, tlen)) 1003 goto findpcb; 1004 return (IPPROTO_DONE); 1005 case TCPS_CLOSED: 1006 /* 1007 * The TCPCB may no longer exist if the connection is winding 1008 * down or it is in the CLOSED state. Either way we drop the 1009 * segment and send an appropriate response. 1010 */ 1011 rstreason = BANDLIM_RST_CLOSEDPORT; 1012 goto dropwithreset; 1013 } 1014 1015 if ((tp->t_port != port) && (tp->t_state > TCPS_LISTEN)) { 1016 rstreason = BANDLIM_RST_CLOSEDPORT; 1017 goto dropwithreset; 1018 } 1019 1020 #ifdef TCP_OFFLOAD 1021 if (tp->t_flags & TF_TOE) { 1022 tcp_offload_input(tp, m); 1023 m = NULL; /* consumed by the TOE driver */ 1024 goto dropunlock; 1025 } 1026 #endif 1027 1028 #ifdef MAC 1029 if (mac_inpcb_check_deliver(inp, m)) 1030 goto dropunlock; 1031 #endif 1032 so = inp->inp_socket; 1033 KASSERT(so != NULL, ("%s: so == NULL", __func__)); 1034 #ifdef TCPDEBUG 1035 if (so->so_options & SO_DEBUG) { 1036 ostate = tp->t_state; 1037 #ifdef INET6 1038 if (isipv6) { 1039 bcopy((char *)ip6, (char *)tcp_saveipgen, sizeof(*ip6)); 1040 } else 1041 #endif 1042 bcopy((char *)ip, (char *)tcp_saveipgen, sizeof(*ip)); 1043 tcp_savetcp = *th; 1044 } 1045 #endif /* TCPDEBUG */ 1046 /* 1047 * When the socket is accepting connections (the INPCB is in LISTEN 1048 * state) we look into the SYN cache if this is a new connection 1049 * attempt or the completion of a previous one. 1050 */ 1051 KASSERT(tp->t_state == TCPS_LISTEN || !SOLISTENING(so), 1052 ("%s: so accepting but tp %p not listening", __func__, tp)); 1053 if (tp->t_state == TCPS_LISTEN && SOLISTENING(so)) { 1054 struct in_conninfo inc; 1055 1056 bzero(&inc, sizeof(inc)); 1057 #ifdef INET6 1058 if (isipv6) { 1059 inc.inc_flags |= INC_ISIPV6; 1060 if (inp->inp_inc.inc_flags & INC_IPV6MINMTU) 1061 inc.inc_flags |= INC_IPV6MINMTU; 1062 inc.inc6_faddr = ip6->ip6_src; 1063 inc.inc6_laddr = ip6->ip6_dst; 1064 } else 1065 #endif 1066 { 1067 inc.inc_faddr = ip->ip_src; 1068 inc.inc_laddr = ip->ip_dst; 1069 } 1070 inc.inc_fport = th->th_sport; 1071 inc.inc_lport = th->th_dport; 1072 inc.inc_fibnum = so->so_fibnum; 1073 1074 /* 1075 * Check for an existing connection attempt in syncache if 1076 * the flag is only ACK. A successful lookup creates a new 1077 * socket appended to the listen queue in SYN_RECEIVED state. 1078 */ 1079 if ((thflags & (TH_RST|TH_ACK|TH_SYN)) == TH_ACK) { 1080 /* 1081 * Parse the TCP options here because 1082 * syncookies need access to the reflected 1083 * timestamp. 1084 */ 1085 tcp_dooptions(&to, optp, optlen, 0); 1086 /* 1087 * NB: syncache_expand() doesn't unlock inp. 1088 */ 1089 rstreason = syncache_expand(&inc, &to, th, &so, m, port); 1090 if (rstreason < 0) { 1091 /* 1092 * A failing TCP MD5 signature comparison 1093 * must result in the segment being dropped 1094 * and must not produce any response back 1095 * to the sender. 1096 */ 1097 goto dropunlock; 1098 } else if (rstreason == 0) { 1099 /* 1100 * No syncache entry, or ACK was not for our 1101 * SYN/ACK. Do our protection against double 1102 * ACK. If peer sent us 2 ACKs, then for the 1103 * first one syncache_expand() successfully 1104 * converted syncache entry into a socket, 1105 * while we were waiting on the inpcb lock. We 1106 * don't want to sent RST for the second ACK, 1107 * so we perform second lookup without wildcard 1108 * match, hoping to find the new socket. If 1109 * the ACK is stray indeed, rstreason would 1110 * hint the above code that the lookup was a 1111 * second attempt. 1112 * 1113 * NB: syncache did its own logging 1114 * of the failure cause. 1115 */ 1116 INP_WUNLOCK(inp); 1117 rstreason = BANDLIM_RST_OPENPORT; 1118 lookupflag &= ~INPLOOKUP_WILDCARD; 1119 goto findpcb; 1120 } 1121 tfo_socket_result: 1122 if (so == NULL) { 1123 /* 1124 * We completed the 3-way handshake 1125 * but could not allocate a socket 1126 * either due to memory shortage, 1127 * listen queue length limits or 1128 * global socket limits. Send RST 1129 * or wait and have the remote end 1130 * retransmit the ACK for another 1131 * try. 1132 */ 1133 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1134 log(LOG_DEBUG, "%s; %s: Listen socket: " 1135 "Socket allocation failed due to " 1136 "limits or memory shortage, %s\n", 1137 s, __func__, 1138 V_tcp_sc_rst_sock_fail ? 1139 "sending RST" : "try again"); 1140 if (V_tcp_sc_rst_sock_fail) { 1141 rstreason = BANDLIM_UNLIMITED; 1142 goto dropwithreset; 1143 } else 1144 goto dropunlock; 1145 } 1146 /* 1147 * Socket is created in state SYN_RECEIVED. 1148 * Unlock the listen socket, lock the newly 1149 * created socket and update the tp variable. 1150 * If we came here via jump to tfo_socket_result, 1151 * then listening socket is read-locked. 1152 */ 1153 INP_UNLOCK(inp); /* listen socket */ 1154 inp = sotoinpcb(so); 1155 /* 1156 * New connection inpcb is already locked by 1157 * syncache_expand(). 1158 */ 1159 INP_WLOCK_ASSERT(inp); 1160 tp = intotcpcb(inp); 1161 KASSERT(tp->t_state == TCPS_SYN_RECEIVED, 1162 ("%s: ", __func__)); 1163 /* 1164 * Process the segment and the data it 1165 * contains. tcp_do_segment() consumes 1166 * the mbuf chain and unlocks the inpcb. 1167 */ 1168 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1169 tp->t_fb->tfb_tcp_do_segment(m, th, so, tp, drop_hdrlen, tlen, 1170 iptos); 1171 return (IPPROTO_DONE); 1172 } 1173 /* 1174 * Segment flag validation for new connection attempts: 1175 * 1176 * Our (SYN|ACK) response was rejected. 1177 * Check with syncache and remove entry to prevent 1178 * retransmits. 1179 * 1180 * NB: syncache_chkrst does its own logging of failure 1181 * causes. 1182 */ 1183 if (thflags & TH_RST) { 1184 syncache_chkrst(&inc, th, m, port); 1185 goto dropunlock; 1186 } 1187 /* 1188 * We can't do anything without SYN. 1189 */ 1190 if ((thflags & TH_SYN) == 0) { 1191 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1192 log(LOG_DEBUG, "%s; %s: Listen socket: " 1193 "SYN is missing, segment ignored\n", 1194 s, __func__); 1195 TCPSTAT_INC(tcps_badsyn); 1196 goto dropunlock; 1197 } 1198 /* 1199 * (SYN|ACK) is bogus on a listen socket. 1200 */ 1201 if (thflags & TH_ACK) { 1202 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1203 log(LOG_DEBUG, "%s; %s: Listen socket: " 1204 "SYN|ACK invalid, segment rejected\n", 1205 s, __func__); 1206 syncache_badack(&inc, port); /* XXX: Not needed! */ 1207 TCPSTAT_INC(tcps_badsyn); 1208 rstreason = BANDLIM_RST_OPENPORT; 1209 goto dropwithreset; 1210 } 1211 /* 1212 * If the drop_synfin option is enabled, drop all 1213 * segments with both the SYN and FIN bits set. 1214 * This prevents e.g. nmap from identifying the 1215 * TCP/IP stack. 1216 * XXX: Poor reasoning. nmap has other methods 1217 * and is constantly refining its stack detection 1218 * strategies. 1219 * XXX: This is a violation of the TCP specification 1220 * and was used by RFC1644. 1221 */ 1222 if ((thflags & TH_FIN) && V_drop_synfin) { 1223 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1224 log(LOG_DEBUG, "%s; %s: Listen socket: " 1225 "SYN|FIN segment ignored (based on " 1226 "sysctl setting)\n", s, __func__); 1227 TCPSTAT_INC(tcps_badsyn); 1228 goto dropunlock; 1229 } 1230 /* 1231 * Segment's flags are (SYN) or (SYN|FIN). 1232 * 1233 * TH_PUSH, TH_URG, TH_ECE, TH_CWR are ignored 1234 * as they do not affect the state of the TCP FSM. 1235 * The data pointed to by TH_URG and th_urp is ignored. 1236 */ 1237 KASSERT((thflags & (TH_RST|TH_ACK)) == 0, 1238 ("%s: Listen socket: TH_RST or TH_ACK set", __func__)); 1239 KASSERT(thflags & (TH_SYN), 1240 ("%s: Listen socket: TH_SYN not set", __func__)); 1241 INP_RLOCK_ASSERT(inp); 1242 #ifdef INET6 1243 /* 1244 * If deprecated address is forbidden, 1245 * we do not accept SYN to deprecated interface 1246 * address to prevent any new inbound connection from 1247 * getting established. 1248 * When we do not accept SYN, we send a TCP RST, 1249 * with deprecated source address (instead of dropping 1250 * it). We compromise it as it is much better for peer 1251 * to send a RST, and RST will be the final packet 1252 * for the exchange. 1253 * 1254 * If we do not forbid deprecated addresses, we accept 1255 * the SYN packet. RFC2462 does not suggest dropping 1256 * SYN in this case. 1257 * If we decipher RFC2462 5.5.4, it says like this: 1258 * 1. use of deprecated addr with existing 1259 * communication is okay - "SHOULD continue to be 1260 * used" 1261 * 2. use of it with new communication: 1262 * (2a) "SHOULD NOT be used if alternate address 1263 * with sufficient scope is available" 1264 * (2b) nothing mentioned otherwise. 1265 * Here we fall into (2b) case as we have no choice in 1266 * our source address selection - we must obey the peer. 1267 * 1268 * The wording in RFC2462 is confusing, and there are 1269 * multiple description text for deprecated address 1270 * handling - worse, they are not exactly the same. 1271 * I believe 5.5.4 is the best one, so we follow 5.5.4. 1272 */ 1273 if (isipv6 && !V_ip6_use_deprecated) { 1274 struct in6_ifaddr *ia6; 1275 1276 ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */, false); 1277 if (ia6 != NULL && 1278 (ia6->ia6_flags & IN6_IFF_DEPRECATED)) { 1279 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1280 log(LOG_DEBUG, "%s; %s: Listen socket: " 1281 "Connection attempt to deprecated " 1282 "IPv6 address rejected\n", 1283 s, __func__); 1284 rstreason = BANDLIM_RST_OPENPORT; 1285 goto dropwithreset; 1286 } 1287 } 1288 #endif /* INET6 */ 1289 /* 1290 * Basic sanity checks on incoming SYN requests: 1291 * Don't respond if the destination is a link layer 1292 * broadcast according to RFC1122 4.2.3.10, p. 104. 1293 * If it is from this socket it must be forged. 1294 * Don't respond if the source or destination is a 1295 * global or subnet broad- or multicast address. 1296 * Note that it is quite possible to receive unicast 1297 * link-layer packets with a broadcast IP address. Use 1298 * in_broadcast() to find them. 1299 */ 1300 if (m->m_flags & (M_BCAST|M_MCAST)) { 1301 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1302 log(LOG_DEBUG, "%s; %s: Listen socket: " 1303 "Connection attempt from broad- or multicast " 1304 "link layer address ignored\n", s, __func__); 1305 goto dropunlock; 1306 } 1307 #ifdef INET6 1308 if (isipv6) { 1309 if (th->th_dport == th->th_sport && 1310 IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &ip6->ip6_src)) { 1311 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1312 log(LOG_DEBUG, "%s; %s: Listen socket: " 1313 "Connection attempt to/from self " 1314 "ignored\n", s, __func__); 1315 goto dropunlock; 1316 } 1317 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 1318 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) { 1319 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1320 log(LOG_DEBUG, "%s; %s: Listen socket: " 1321 "Connection attempt from/to multicast " 1322 "address ignored\n", s, __func__); 1323 goto dropunlock; 1324 } 1325 } 1326 #endif 1327 #if defined(INET) && defined(INET6) 1328 else 1329 #endif 1330 #ifdef INET 1331 { 1332 if (th->th_dport == th->th_sport && 1333 ip->ip_dst.s_addr == ip->ip_src.s_addr) { 1334 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1335 log(LOG_DEBUG, "%s; %s: Listen socket: " 1336 "Connection attempt from/to self " 1337 "ignored\n", s, __func__); 1338 goto dropunlock; 1339 } 1340 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || 1341 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 1342 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || 1343 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) { 1344 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1345 log(LOG_DEBUG, "%s; %s: Listen socket: " 1346 "Connection attempt from/to broad- " 1347 "or multicast address ignored\n", 1348 s, __func__); 1349 goto dropunlock; 1350 } 1351 } 1352 #endif 1353 /* 1354 * SYN appears to be valid. Create compressed TCP state 1355 * for syncache. 1356 */ 1357 #ifdef TCPDEBUG 1358 if (so->so_options & SO_DEBUG) 1359 tcp_trace(TA_INPUT, ostate, tp, 1360 (void *)tcp_saveipgen, &tcp_savetcp, 0); 1361 #endif 1362 TCP_PROBE3(debug__input, tp, th, m); 1363 tcp_dooptions(&to, optp, optlen, TO_SYN); 1364 if ((so = syncache_add(&inc, &to, th, inp, so, m, NULL, NULL, 1365 iptos, port)) != NULL) 1366 goto tfo_socket_result; 1367 1368 /* 1369 * Entry added to syncache and mbuf consumed. 1370 * Only the listen socket is unlocked by syncache_add(). 1371 */ 1372 return (IPPROTO_DONE); 1373 } else if (tp->t_state == TCPS_LISTEN) { 1374 /* 1375 * When a listen socket is torn down the SO_ACCEPTCONN 1376 * flag is removed first while connections are drained 1377 * from the accept queue in a unlock/lock cycle of the 1378 * ACCEPT_LOCK, opening a race condition allowing a SYN 1379 * attempt go through unhandled. 1380 */ 1381 goto dropunlock; 1382 } 1383 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 1384 if (tp->t_flags & TF_SIGNATURE) { 1385 tcp_dooptions(&to, optp, optlen, thflags); 1386 if ((to.to_flags & TOF_SIGNATURE) == 0) { 1387 TCPSTAT_INC(tcps_sig_err_nosigopt); 1388 goto dropunlock; 1389 } 1390 if (!TCPMD5_ENABLED() || 1391 TCPMD5_INPUT(m, th, to.to_signature) != 0) 1392 goto dropunlock; 1393 } 1394 #endif 1395 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1396 1397 /* 1398 * Segment belongs to a connection in SYN_SENT, ESTABLISHED or later 1399 * state. tcp_do_segment() always consumes the mbuf chain, unlocks 1400 * the inpcb, and unlocks pcbinfo. 1401 * 1402 * XXXGL: in case of a pure SYN arriving on existing connection 1403 * TCP stacks won't need to modify the PCB, they would either drop 1404 * the segment silently, or send a challenge ACK. However, we try 1405 * to upgrade the lock, because calling convention for stacks is 1406 * write-lock on PCB. If upgrade fails, drop the SYN. 1407 */ 1408 if ((lookupflag & INPLOOKUP_RLOCKPCB) && INP_TRY_UPGRADE(inp) == 0) 1409 goto dropunlock; 1410 1411 tp->t_fb->tfb_tcp_do_segment(m, th, so, tp, drop_hdrlen, tlen, iptos); 1412 return (IPPROTO_DONE); 1413 1414 dropwithreset: 1415 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1416 1417 if (inp != NULL) { 1418 tcp_dropwithreset(m, th, tp, tlen, rstreason); 1419 INP_UNLOCK(inp); 1420 } else 1421 tcp_dropwithreset(m, th, NULL, tlen, rstreason); 1422 m = NULL; /* mbuf chain got consumed. */ 1423 goto drop; 1424 1425 dropunlock: 1426 if (m != NULL) 1427 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1428 1429 if (inp != NULL) 1430 INP_UNLOCK(inp); 1431 1432 drop: 1433 if (s != NULL) 1434 free(s, M_TCPLOG); 1435 if (m != NULL) 1436 m_freem(m); 1437 return (IPPROTO_DONE); 1438 } 1439 1440 /* 1441 * Automatic sizing of receive socket buffer. Often the send 1442 * buffer size is not optimally adjusted to the actual network 1443 * conditions at hand (delay bandwidth product). Setting the 1444 * buffer size too small limits throughput on links with high 1445 * bandwidth and high delay (eg. trans-continental/oceanic links). 1446 * 1447 * On the receive side the socket buffer memory is only rarely 1448 * used to any significant extent. This allows us to be much 1449 * more aggressive in scaling the receive socket buffer. For 1450 * the case that the buffer space is actually used to a large 1451 * extent and we run out of kernel memory we can simply drop 1452 * the new segments; TCP on the sender will just retransmit it 1453 * later. Setting the buffer size too big may only consume too 1454 * much kernel memory if the application doesn't read() from 1455 * the socket or packet loss or reordering makes use of the 1456 * reassembly queue. 1457 * 1458 * The criteria to step up the receive buffer one notch are: 1459 * 1. Application has not set receive buffer size with 1460 * SO_RCVBUF. Setting SO_RCVBUF clears SB_AUTOSIZE. 1461 * 2. the number of bytes received during 1/2 of an sRTT 1462 * is at least 3/8 of the current socket buffer size. 1463 * 3. receive buffer size has not hit maximal automatic size; 1464 * 1465 * If all of the criteria are met we increaset the socket buffer 1466 * by a 1/2 (bounded by the max). This allows us to keep ahead 1467 * of slow-start but also makes it so our peer never gets limited 1468 * by our rwnd which we then open up causing a burst. 1469 * 1470 * This algorithm does two steps per RTT at most and only if 1471 * we receive a bulk stream w/o packet losses or reorderings. 1472 * Shrinking the buffer during idle times is not necessary as 1473 * it doesn't consume any memory when idle. 1474 * 1475 * TODO: Only step up if the application is actually serving 1476 * the buffer to better manage the socket buffer resources. 1477 */ 1478 int 1479 tcp_autorcvbuf(struct mbuf *m, struct tcphdr *th, struct socket *so, 1480 struct tcpcb *tp, int tlen) 1481 { 1482 int newsize = 0; 1483 1484 if (V_tcp_do_autorcvbuf && (so->so_rcv.sb_flags & SB_AUTOSIZE) && 1485 tp->t_srtt != 0 && tp->rfbuf_ts != 0 && 1486 TCP_TS_TO_TICKS(tcp_ts_getticks() - tp->rfbuf_ts) > 1487 ((tp->t_srtt >> TCP_RTT_SHIFT)/2)) { 1488 if (tp->rfbuf_cnt > ((so->so_rcv.sb_hiwat / 2)/ 4 * 3) && 1489 so->so_rcv.sb_hiwat < V_tcp_autorcvbuf_max) { 1490 newsize = min((so->so_rcv.sb_hiwat + (so->so_rcv.sb_hiwat/2)), V_tcp_autorcvbuf_max); 1491 } 1492 TCP_PROBE6(receive__autoresize, NULL, tp, m, tp, th, newsize); 1493 1494 /* Start over with next RTT. */ 1495 tp->rfbuf_ts = 0; 1496 tp->rfbuf_cnt = 0; 1497 } else { 1498 tp->rfbuf_cnt += tlen; /* add up */ 1499 } 1500 return (newsize); 1501 } 1502 1503 int 1504 tcp_input(struct mbuf **mp, int *offp, int proto) 1505 { 1506 return(tcp_input_with_port(mp, offp, proto, 0)); 1507 } 1508 1509 static void 1510 tcp_handle_wakeup(struct tcpcb *tp) 1511 { 1512 1513 INP_WLOCK_ASSERT(tp->t_inpcb); 1514 1515 if (tp->t_flags & TF_WAKESOR) { 1516 struct socket *so = tp->t_inpcb->inp_socket; 1517 1518 tp->t_flags &= ~TF_WAKESOR; 1519 SOCKBUF_LOCK_ASSERT(&so->so_rcv); 1520 sorwakeup_locked(so); 1521 } 1522 } 1523 1524 void 1525 tcp_do_segment(struct mbuf *m, struct tcphdr *th, struct socket *so, 1526 struct tcpcb *tp, int drop_hdrlen, int tlen, uint8_t iptos) 1527 { 1528 uint16_t thflags; 1529 int acked, ourfinisacked, needoutput = 0, sack_changed; 1530 int rstreason, todrop, win, incforsyn = 0; 1531 uint32_t tiwin; 1532 uint16_t nsegs; 1533 char *s; 1534 struct in_conninfo *inc; 1535 struct mbuf *mfree; 1536 struct tcpopt to; 1537 int tfo_syn; 1538 u_int maxseg; 1539 1540 #ifdef TCPDEBUG 1541 /* 1542 * The size of tcp_saveipgen must be the size of the max ip header, 1543 * now IPv6. 1544 */ 1545 u_char tcp_saveipgen[IP6_HDR_LEN]; 1546 struct tcphdr tcp_savetcp; 1547 short ostate = 0; 1548 #endif 1549 thflags = tcp_get_flags(th); 1550 inc = &tp->t_inpcb->inp_inc; 1551 tp->sackhint.last_sack_ack = 0; 1552 sack_changed = 0; 1553 nsegs = max(1, m->m_pkthdr.lro_nsegs); 1554 1555 NET_EPOCH_ASSERT(); 1556 INP_WLOCK_ASSERT(tp->t_inpcb); 1557 KASSERT(tp->t_state > TCPS_LISTEN, ("%s: TCPS_LISTEN", 1558 __func__)); 1559 KASSERT(tp->t_state != TCPS_TIME_WAIT, ("%s: TCPS_TIME_WAIT", 1560 __func__)); 1561 1562 #ifdef TCPPCAP 1563 /* Save segment, if requested. */ 1564 tcp_pcap_add(th, m, &(tp->t_inpkts)); 1565 #endif 1566 TCP_LOG_EVENT(tp, th, &so->so_rcv, &so->so_snd, TCP_LOG_IN, 0, 1567 tlen, NULL, true); 1568 1569 if ((thflags & TH_SYN) && (thflags & TH_FIN) && V_drop_synfin) { 1570 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1571 log(LOG_DEBUG, "%s; %s: " 1572 "SYN|FIN segment ignored (based on " 1573 "sysctl setting)\n", s, __func__); 1574 free(s, M_TCPLOG); 1575 } 1576 goto drop; 1577 } 1578 1579 /* 1580 * If a segment with the ACK-bit set arrives in the SYN-SENT state 1581 * check SEQ.ACK first. 1582 */ 1583 if ((tp->t_state == TCPS_SYN_SENT) && (thflags & TH_ACK) && 1584 (SEQ_LEQ(th->th_ack, tp->iss) || SEQ_GT(th->th_ack, tp->snd_max))) { 1585 rstreason = BANDLIM_UNLIMITED; 1586 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 1587 goto dropwithreset; 1588 } 1589 1590 /* 1591 * Segment received on connection. 1592 * Reset idle time and keep-alive timer. 1593 * XXX: This should be done after segment 1594 * validation to ignore broken/spoofed segs. 1595 */ 1596 if (tp->t_idle_reduce && 1597 (tp->snd_max == tp->snd_una) && 1598 ((ticks - tp->t_rcvtime) >= tp->t_rxtcur)) 1599 cc_after_idle(tp); 1600 tp->t_rcvtime = ticks; 1601 1602 if (thflags & TH_FIN) 1603 tcp_log_end_status(tp, TCP_EI_STATUS_CLIENT_FIN); 1604 /* 1605 * Scale up the window into a 32-bit value. 1606 * For the SYN_SENT state the scale is zero. 1607 */ 1608 tiwin = th->th_win << tp->snd_scale; 1609 #ifdef STATS 1610 stats_voi_update_abs_ulong(tp->t_stats, VOI_TCP_FRWIN, tiwin); 1611 #endif 1612 1613 /* 1614 * TCP ECN processing. 1615 */ 1616 if (tcp_ecn_input_segment(tp, thflags, tlen, 1617 tcp_packets_this_ack(tp, th->th_ack), 1618 iptos)) 1619 cc_cong_signal(tp, th, CC_ECN); 1620 1621 /* 1622 * Parse options on any incoming segment. 1623 */ 1624 tcp_dooptions(&to, (u_char *)(th + 1), 1625 (th->th_off << 2) - sizeof(struct tcphdr), 1626 (thflags & TH_SYN) ? TO_SYN : 0); 1627 1628 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 1629 if ((tp->t_flags & TF_SIGNATURE) != 0 && 1630 (to.to_flags & TOF_SIGNATURE) == 0) { 1631 TCPSTAT_INC(tcps_sig_err_sigopt); 1632 /* XXX: should drop? */ 1633 } 1634 #endif 1635 /* 1636 * If echoed timestamp is later than the current time, 1637 * fall back to non RFC1323 RTT calculation. Normalize 1638 * timestamp if syncookies were used when this connection 1639 * was established. 1640 */ 1641 if ((to.to_flags & TOF_TS) && (to.to_tsecr != 0)) { 1642 to.to_tsecr -= tp->ts_offset; 1643 if (TSTMP_GT(to.to_tsecr, tcp_ts_getticks())) 1644 to.to_tsecr = 0; 1645 else if (tp->t_rxtshift == 1 && 1646 tp->t_flags & TF_PREVVALID && 1647 tp->t_badrxtwin != 0 && 1648 TSTMP_LT(to.to_tsecr, tp->t_badrxtwin)) 1649 cc_cong_signal(tp, th, CC_RTO_ERR); 1650 } 1651 /* 1652 * Process options only when we get SYN/ACK back. The SYN case 1653 * for incoming connections is handled in tcp_syncache. 1654 * According to RFC1323 the window field in a SYN (i.e., a <SYN> 1655 * or <SYN,ACK>) segment itself is never scaled. 1656 * XXX this is traditional behavior, may need to be cleaned up. 1657 */ 1658 if (tp->t_state == TCPS_SYN_SENT && (thflags & TH_SYN)) { 1659 /* Handle parallel SYN for ECN */ 1660 tcp_ecn_input_parallel_syn(tp, thflags, iptos); 1661 if ((to.to_flags & TOF_SCALE) && 1662 (tp->t_flags & TF_REQ_SCALE) && 1663 !(tp->t_flags & TF_NOOPT)) { 1664 tp->t_flags |= TF_RCVD_SCALE; 1665 tp->snd_scale = to.to_wscale; 1666 } else 1667 tp->t_flags &= ~TF_REQ_SCALE; 1668 /* 1669 * Initial send window. It will be updated with 1670 * the next incoming segment to the scaled value. 1671 */ 1672 tp->snd_wnd = th->th_win; 1673 if ((to.to_flags & TOF_TS) && 1674 (tp->t_flags & TF_REQ_TSTMP) && 1675 !(tp->t_flags & TF_NOOPT)) { 1676 tp->t_flags |= TF_RCVD_TSTMP; 1677 tp->ts_recent = to.to_tsval; 1678 tp->ts_recent_age = tcp_ts_getticks(); 1679 } else 1680 tp->t_flags &= ~TF_REQ_TSTMP; 1681 if (to.to_flags & TOF_MSS) 1682 tcp_mss(tp, to.to_mss); 1683 if ((tp->t_flags & TF_SACK_PERMIT) && 1684 (!(to.to_flags & TOF_SACKPERM) || 1685 (tp->t_flags & TF_NOOPT))) 1686 tp->t_flags &= ~TF_SACK_PERMIT; 1687 if (IS_FASTOPEN(tp->t_flags)) { 1688 if ((to.to_flags & TOF_FASTOPEN) && 1689 !(tp->t_flags & TF_NOOPT)) { 1690 uint16_t mss; 1691 1692 if (to.to_flags & TOF_MSS) 1693 mss = to.to_mss; 1694 else 1695 if ((tp->t_inpcb->inp_vflag & INP_IPV6) != 0) 1696 mss = TCP6_MSS; 1697 else 1698 mss = TCP_MSS; 1699 tcp_fastopen_update_cache(tp, mss, 1700 to.to_tfo_len, to.to_tfo_cookie); 1701 } else 1702 tcp_fastopen_disable_path(tp); 1703 } 1704 } 1705 1706 /* 1707 * If timestamps were negotiated during SYN/ACK and a 1708 * segment without a timestamp is received, silently drop 1709 * the segment, unless it is a RST segment or missing timestamps are 1710 * tolerated. 1711 * See section 3.2 of RFC 7323. 1712 */ 1713 if ((tp->t_flags & TF_RCVD_TSTMP) && !(to.to_flags & TOF_TS)) { 1714 if (((thflags & TH_RST) != 0) || V_tcp_tolerate_missing_ts) { 1715 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1716 log(LOG_DEBUG, "%s; %s: Timestamp missing, " 1717 "segment processed normally\n", 1718 s, __func__); 1719 free(s, M_TCPLOG); 1720 } 1721 } else { 1722 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1723 log(LOG_DEBUG, "%s; %s: Timestamp missing, " 1724 "segment silently dropped\n", s, __func__); 1725 free(s, M_TCPLOG); 1726 } 1727 goto drop; 1728 } 1729 } 1730 /* 1731 * If timestamps were not negotiated during SYN/ACK and a 1732 * segment with a timestamp is received, ignore the 1733 * timestamp and process the packet normally. 1734 * See section 3.2 of RFC 7323. 1735 */ 1736 if (!(tp->t_flags & TF_RCVD_TSTMP) && (to.to_flags & TOF_TS)) { 1737 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1738 log(LOG_DEBUG, "%s; %s: Timestamp not expected, " 1739 "segment processed normally\n", s, __func__); 1740 free(s, M_TCPLOG); 1741 } 1742 } 1743 1744 /* 1745 * Header prediction: check for the two common cases 1746 * of a uni-directional data xfer. If the packet has 1747 * no control flags, is in-sequence, the window didn't 1748 * change and we're not retransmitting, it's a 1749 * candidate. If the length is zero and the ack moved 1750 * forward, we're the sender side of the xfer. Just 1751 * free the data acked & wake any higher level process 1752 * that was blocked waiting for space. If the length 1753 * is non-zero and the ack didn't move, we're the 1754 * receiver side. If we're getting packets in-order 1755 * (the reassembly queue is empty), add the data to 1756 * the socket buffer and note that we need a delayed ack. 1757 * Make sure that the hidden state-flags are also off. 1758 * Since we check for TCPS_ESTABLISHED first, it can only 1759 * be TH_NEEDSYN. 1760 */ 1761 if (tp->t_state == TCPS_ESTABLISHED && 1762 th->th_seq == tp->rcv_nxt && 1763 (thflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK && 1764 tp->snd_nxt == tp->snd_max && 1765 tiwin && tiwin == tp->snd_wnd && 1766 ((tp->t_flags & (TF_NEEDSYN|TF_NEEDFIN)) == 0) && 1767 SEGQ_EMPTY(tp) && 1768 ((to.to_flags & TOF_TS) == 0 || 1769 TSTMP_GEQ(to.to_tsval, tp->ts_recent)) ) { 1770 /* 1771 * If last ACK falls within this segment's sequence numbers, 1772 * record the timestamp. 1773 * NOTE that the test is modified according to the latest 1774 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 1775 */ 1776 if ((to.to_flags & TOF_TS) != 0 && 1777 SEQ_LEQ(th->th_seq, tp->last_ack_sent)) { 1778 tp->ts_recent_age = tcp_ts_getticks(); 1779 tp->ts_recent = to.to_tsval; 1780 } 1781 1782 if (tlen == 0) { 1783 if (SEQ_GT(th->th_ack, tp->snd_una) && 1784 SEQ_LEQ(th->th_ack, tp->snd_max) && 1785 !IN_RECOVERY(tp->t_flags) && 1786 (to.to_flags & TOF_SACK) == 0 && 1787 TAILQ_EMPTY(&tp->snd_holes)) { 1788 /* 1789 * This is a pure ack for outstanding data. 1790 */ 1791 TCPSTAT_INC(tcps_predack); 1792 1793 /* 1794 * "bad retransmit" recovery without timestamps. 1795 */ 1796 if ((to.to_flags & TOF_TS) == 0 && 1797 tp->t_rxtshift == 1 && 1798 tp->t_flags & TF_PREVVALID && 1799 tp->t_badrxtwin != 0 && 1800 TSTMP_LT(ticks, tp->t_badrxtwin)) { 1801 cc_cong_signal(tp, th, CC_RTO_ERR); 1802 } 1803 1804 /* 1805 * Recalculate the transmit timer / rtt. 1806 * 1807 * Some boxes send broken timestamp replies 1808 * during the SYN+ACK phase, ignore 1809 * timestamps of 0 or we could calculate a 1810 * huge RTT and blow up the retransmit timer. 1811 */ 1812 if ((to.to_flags & TOF_TS) != 0 && 1813 to.to_tsecr) { 1814 uint32_t t; 1815 1816 t = tcp_ts_getticks() - to.to_tsecr; 1817 if (!tp->t_rttlow || tp->t_rttlow > t) 1818 tp->t_rttlow = t; 1819 tcp_xmit_timer(tp, 1820 TCP_TS_TO_TICKS(t) + 1); 1821 } else if (tp->t_rtttime && 1822 SEQ_GT(th->th_ack, tp->t_rtseq)) { 1823 if (!tp->t_rttlow || 1824 tp->t_rttlow > ticks - tp->t_rtttime) 1825 tp->t_rttlow = ticks - tp->t_rtttime; 1826 tcp_xmit_timer(tp, 1827 ticks - tp->t_rtttime); 1828 } 1829 acked = BYTES_THIS_ACK(tp, th); 1830 1831 #ifdef TCP_HHOOK 1832 /* Run HHOOK_TCP_ESTABLISHED_IN helper hooks. */ 1833 hhook_run_tcp_est_in(tp, th, &to); 1834 #endif 1835 1836 TCPSTAT_ADD(tcps_rcvackpack, nsegs); 1837 TCPSTAT_ADD(tcps_rcvackbyte, acked); 1838 sbdrop(&so->so_snd, acked); 1839 if (SEQ_GT(tp->snd_una, tp->snd_recover) && 1840 SEQ_LEQ(th->th_ack, tp->snd_recover)) 1841 tp->snd_recover = th->th_ack - 1; 1842 1843 /* 1844 * Let the congestion control algorithm update 1845 * congestion control related information. This 1846 * typically means increasing the congestion 1847 * window. 1848 */ 1849 cc_ack_received(tp, th, nsegs, CC_ACK); 1850 1851 tp->snd_una = th->th_ack; 1852 /* 1853 * Pull snd_wl2 up to prevent seq wrap relative 1854 * to th_ack. 1855 */ 1856 tp->snd_wl2 = th->th_ack; 1857 tp->t_dupacks = 0; 1858 m_freem(m); 1859 1860 /* 1861 * If all outstanding data are acked, stop 1862 * retransmit timer, otherwise restart timer 1863 * using current (possibly backed-off) value. 1864 * If process is waiting for space, 1865 * wakeup/selwakeup/signal. If data 1866 * are ready to send, let tcp_output 1867 * decide between more output or persist. 1868 */ 1869 #ifdef TCPDEBUG 1870 if (so->so_options & SO_DEBUG) 1871 tcp_trace(TA_INPUT, ostate, tp, 1872 (void *)tcp_saveipgen, 1873 &tcp_savetcp, 0); 1874 #endif 1875 TCP_PROBE3(debug__input, tp, th, m); 1876 /* 1877 * Clear t_acktime if remote side has ACKd 1878 * all data in the socket buffer. 1879 * Otherwise, update t_acktime if we received 1880 * a sufficiently large ACK. 1881 */ 1882 if (sbavail(&so->so_snd) == 0) 1883 tp->t_acktime = 0; 1884 else if (acked > 1) 1885 tp->t_acktime = ticks; 1886 if (tp->snd_una == tp->snd_max) 1887 tcp_timer_activate(tp, TT_REXMT, 0); 1888 else if (!tcp_timer_active(tp, TT_PERSIST)) 1889 tcp_timer_activate(tp, TT_REXMT, 1890 TP_RXTCUR(tp)); 1891 sowwakeup(so); 1892 if (sbavail(&so->so_snd)) 1893 (void) tcp_output(tp); 1894 goto check_delack; 1895 } 1896 } else if (th->th_ack == tp->snd_una && 1897 tlen <= sbspace(&so->so_rcv)) { 1898 int newsize = 0; /* automatic sockbuf scaling */ 1899 1900 /* 1901 * This is a pure, in-sequence data packet with 1902 * nothing on the reassembly queue and we have enough 1903 * buffer space to take it. 1904 */ 1905 /* Clean receiver SACK report if present */ 1906 if ((tp->t_flags & TF_SACK_PERMIT) && tp->rcv_numsacks) 1907 tcp_clean_sackreport(tp); 1908 TCPSTAT_INC(tcps_preddat); 1909 tp->rcv_nxt += tlen; 1910 if (tlen && 1911 ((tp->t_flags2 & TF2_FBYTES_COMPLETE) == 0) && 1912 (tp->t_fbyte_in == 0)) { 1913 tp->t_fbyte_in = ticks; 1914 if (tp->t_fbyte_in == 0) 1915 tp->t_fbyte_in = 1; 1916 if (tp->t_fbyte_out && tp->t_fbyte_in) 1917 tp->t_flags2 |= TF2_FBYTES_COMPLETE; 1918 } 1919 /* 1920 * Pull snd_wl1 up to prevent seq wrap relative to 1921 * th_seq. 1922 */ 1923 tp->snd_wl1 = th->th_seq; 1924 /* 1925 * Pull rcv_up up to prevent seq wrap relative to 1926 * rcv_nxt. 1927 */ 1928 tp->rcv_up = tp->rcv_nxt; 1929 TCPSTAT_ADD(tcps_rcvpack, nsegs); 1930 TCPSTAT_ADD(tcps_rcvbyte, tlen); 1931 #ifdef TCPDEBUG 1932 if (so->so_options & SO_DEBUG) 1933 tcp_trace(TA_INPUT, ostate, tp, 1934 (void *)tcp_saveipgen, &tcp_savetcp, 0); 1935 #endif 1936 TCP_PROBE3(debug__input, tp, th, m); 1937 1938 newsize = tcp_autorcvbuf(m, th, so, tp, tlen); 1939 1940 /* Add data to socket buffer. */ 1941 SOCKBUF_LOCK(&so->so_rcv); 1942 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 1943 m_freem(m); 1944 } else { 1945 /* 1946 * Set new socket buffer size. 1947 * Give up when limit is reached. 1948 */ 1949 if (newsize) 1950 if (!sbreserve_locked(so, SO_RCV, 1951 newsize, NULL)) 1952 so->so_rcv.sb_flags &= ~SB_AUTOSIZE; 1953 m_adj(m, drop_hdrlen); /* delayed header drop */ 1954 sbappendstream_locked(&so->so_rcv, m, 0); 1955 } 1956 /* NB: sorwakeup_locked() does an implicit unlock. */ 1957 sorwakeup_locked(so); 1958 if (DELAY_ACK(tp, tlen)) { 1959 tp->t_flags |= TF_DELACK; 1960 } else { 1961 tp->t_flags |= TF_ACKNOW; 1962 tcp_output(tp); 1963 } 1964 goto check_delack; 1965 } 1966 } 1967 1968 /* 1969 * Calculate amount of space in receive window, 1970 * and then do TCP input processing. 1971 * Receive window is amount of space in rcv queue, 1972 * but not less than advertised window. 1973 */ 1974 win = sbspace(&so->so_rcv); 1975 if (win < 0) 1976 win = 0; 1977 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 1978 1979 switch (tp->t_state) { 1980 /* 1981 * If the state is SYN_RECEIVED: 1982 * if seg contains an ACK, but not for our SYN/ACK, send a RST. 1983 */ 1984 case TCPS_SYN_RECEIVED: 1985 if ((thflags & TH_ACK) && 1986 (SEQ_LEQ(th->th_ack, tp->snd_una) || 1987 SEQ_GT(th->th_ack, tp->snd_max))) { 1988 rstreason = BANDLIM_RST_OPENPORT; 1989 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 1990 goto dropwithreset; 1991 } 1992 if (IS_FASTOPEN(tp->t_flags)) { 1993 /* 1994 * When a TFO connection is in SYN_RECEIVED, the 1995 * only valid packets are the initial SYN, a 1996 * retransmit/copy of the initial SYN (possibly with 1997 * a subset of the original data), a valid ACK, a 1998 * FIN, or a RST. 1999 */ 2000 if ((thflags & (TH_SYN|TH_ACK)) == (TH_SYN|TH_ACK)) { 2001 rstreason = BANDLIM_RST_OPENPORT; 2002 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 2003 goto dropwithreset; 2004 } else if (thflags & TH_SYN) { 2005 /* non-initial SYN is ignored */ 2006 if ((tcp_timer_active(tp, TT_DELACK) || 2007 tcp_timer_active(tp, TT_REXMT))) 2008 goto drop; 2009 } else if (!(thflags & (TH_ACK|TH_FIN|TH_RST))) { 2010 goto drop; 2011 } 2012 } 2013 break; 2014 2015 /* 2016 * If the state is SYN_SENT: 2017 * if seg contains a RST with valid ACK (SEQ.ACK has already 2018 * been verified), then drop the connection. 2019 * if seg contains a RST without an ACK, drop the seg. 2020 * if seg does not contain SYN, then drop the seg. 2021 * Otherwise this is an acceptable SYN segment 2022 * initialize tp->rcv_nxt and tp->irs 2023 * if seg contains ack then advance tp->snd_una 2024 * if seg contains an ECE and ECN support is enabled, the stream 2025 * is ECN capable. 2026 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 2027 * arrange for segment to be acked (eventually) 2028 * continue processing rest of data/controls, beginning with URG 2029 */ 2030 case TCPS_SYN_SENT: 2031 if ((thflags & (TH_ACK|TH_RST)) == (TH_ACK|TH_RST)) { 2032 TCP_PROBE5(connect__refused, NULL, tp, 2033 m, tp, th); 2034 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 2035 tp = tcp_drop(tp, ECONNREFUSED); 2036 } 2037 if (thflags & TH_RST) 2038 goto drop; 2039 if (!(thflags & TH_SYN)) 2040 goto drop; 2041 2042 tp->irs = th->th_seq; 2043 tcp_rcvseqinit(tp); 2044 if (thflags & TH_ACK) { 2045 int tfo_partial_ack = 0; 2046 2047 TCPSTAT_INC(tcps_connects); 2048 soisconnected(so); 2049 #ifdef MAC 2050 mac_socketpeer_set_from_mbuf(m, so); 2051 #endif 2052 /* Do window scaling on this connection? */ 2053 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2054 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2055 tp->rcv_scale = tp->request_r_scale; 2056 } 2057 tp->rcv_adv += min(tp->rcv_wnd, 2058 TCP_MAXWIN << tp->rcv_scale); 2059 tp->snd_una++; /* SYN is acked */ 2060 /* 2061 * If not all the data that was sent in the TFO SYN 2062 * has been acked, resend the remainder right away. 2063 */ 2064 if (IS_FASTOPEN(tp->t_flags) && 2065 (tp->snd_una != tp->snd_max)) { 2066 tp->snd_nxt = th->th_ack; 2067 tfo_partial_ack = 1; 2068 } 2069 /* 2070 * If there's data, delay ACK; if there's also a FIN 2071 * ACKNOW will be turned on later. 2072 */ 2073 if (DELAY_ACK(tp, tlen) && tlen != 0 && !tfo_partial_ack) 2074 tcp_timer_activate(tp, TT_DELACK, 2075 tcp_delacktime); 2076 else 2077 tp->t_flags |= TF_ACKNOW; 2078 2079 tcp_ecn_input_syn_sent(tp, thflags, iptos); 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 tp->t_acktime = ticks; 2090 tcp_state_change(tp, TCPS_FIN_WAIT_1); 2091 tp->t_flags &= ~TF_NEEDFIN; 2092 thflags &= ~TH_SYN; 2093 } else { 2094 tcp_state_change(tp, TCPS_ESTABLISHED); 2095 TCP_PROBE5(connect__established, NULL, tp, 2096 m, tp, th); 2097 cc_conn_init(tp); 2098 tcp_timer_activate(tp, TT_KEEP, 2099 TP_KEEPIDLE(tp)); 2100 } 2101 } else { 2102 /* 2103 * Received initial SYN in SYN-SENT[*] state => 2104 * simultaneous open. 2105 * If it succeeds, connection is * half-synchronized. 2106 * Otherwise, do 3-way handshake: 2107 * SYN-SENT -> SYN-RECEIVED 2108 * SYN-SENT* -> SYN-RECEIVED* 2109 */ 2110 tp->t_flags |= (TF_ACKNOW | TF_NEEDSYN | TF_SONOTCONN); 2111 tcp_timer_activate(tp, TT_REXMT, 0); 2112 tcp_state_change(tp, TCPS_SYN_RECEIVED); 2113 } 2114 2115 /* 2116 * Advance th->th_seq to correspond to first data byte. 2117 * If data, trim to stay within window, 2118 * dropping FIN if necessary. 2119 */ 2120 th->th_seq++; 2121 if (tlen > tp->rcv_wnd) { 2122 todrop = tlen - tp->rcv_wnd; 2123 m_adj(m, -todrop); 2124 tlen = tp->rcv_wnd; 2125 thflags &= ~TH_FIN; 2126 TCPSTAT_INC(tcps_rcvpackafterwin); 2127 TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); 2128 } 2129 tp->snd_wl1 = th->th_seq - 1; 2130 tp->rcv_up = th->th_seq; 2131 /* 2132 * Client side of transaction: already sent SYN and data. 2133 * If the remote host used T/TCP to validate the SYN, 2134 * our data will be ACK'd; if so, enter normal data segment 2135 * processing in the middle of step 5, ack processing. 2136 * Otherwise, goto step 6. 2137 */ 2138 if (thflags & TH_ACK) 2139 goto process_ACK; 2140 2141 goto step6; 2142 } 2143 2144 /* 2145 * States other than LISTEN or SYN_SENT. 2146 * First check the RST flag and sequence number since reset segments 2147 * are exempt from the timestamp and connection count tests. This 2148 * fixes a bug introduced by the Stevens, vol. 2, p. 960 bugfix 2149 * below which allowed reset segments in half the sequence space 2150 * to fall though and be processed (which gives forged reset 2151 * segments with a random sequence number a 50 percent chance of 2152 * killing a connection). 2153 * Then check timestamp, if present. 2154 * Then check the connection count, if present. 2155 * Then check that at least some bytes of segment are within 2156 * receive window. If segment begins before rcv_nxt, 2157 * drop leading data (and SYN); if nothing left, just ack. 2158 */ 2159 if (thflags & TH_RST) { 2160 /* 2161 * RFC5961 Section 3.2 2162 * 2163 * - RST drops connection only if SEG.SEQ == RCV.NXT. 2164 * - If RST is in window, we send challenge ACK. 2165 * 2166 * Note: to take into account delayed ACKs, we should 2167 * test against last_ack_sent instead of rcv_nxt. 2168 * Note 2: we handle special case of closed window, not 2169 * covered by the RFC. 2170 */ 2171 if ((SEQ_GEQ(th->th_seq, tp->last_ack_sent) && 2172 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) || 2173 (tp->rcv_wnd == 0 && tp->last_ack_sent == th->th_seq)) { 2174 KASSERT(tp->t_state != TCPS_SYN_SENT, 2175 ("%s: TH_RST for TCPS_SYN_SENT th %p tp %p", 2176 __func__, th, tp)); 2177 2178 if (V_tcp_insecure_rst || 2179 tp->last_ack_sent == th->th_seq) { 2180 TCPSTAT_INC(tcps_drops); 2181 /* Drop the connection. */ 2182 switch (tp->t_state) { 2183 case TCPS_SYN_RECEIVED: 2184 so->so_error = ECONNREFUSED; 2185 goto close; 2186 case TCPS_ESTABLISHED: 2187 case TCPS_FIN_WAIT_1: 2188 case TCPS_FIN_WAIT_2: 2189 case TCPS_CLOSE_WAIT: 2190 case TCPS_CLOSING: 2191 case TCPS_LAST_ACK: 2192 so->so_error = ECONNRESET; 2193 close: 2194 /* FALLTHROUGH */ 2195 default: 2196 tcp_log_end_status(tp, TCP_EI_STATUS_CLIENT_RST); 2197 tp = tcp_close(tp); 2198 } 2199 } else { 2200 TCPSTAT_INC(tcps_badrst); 2201 /* Send challenge ACK. */ 2202 tcp_respond(tp, mtod(m, void *), th, m, 2203 tp->rcv_nxt, tp->snd_nxt, TH_ACK); 2204 tp->last_ack_sent = tp->rcv_nxt; 2205 m = NULL; 2206 } 2207 } 2208 goto drop; 2209 } 2210 2211 /* 2212 * RFC5961 Section 4.2 2213 * Send challenge ACK for any SYN in synchronized state. 2214 */ 2215 if ((thflags & TH_SYN) && tp->t_state != TCPS_SYN_SENT && 2216 tp->t_state != TCPS_SYN_RECEIVED) { 2217 TCPSTAT_INC(tcps_badsyn); 2218 if (V_tcp_insecure_syn && 2219 SEQ_GEQ(th->th_seq, tp->last_ack_sent) && 2220 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) { 2221 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 2222 tp = tcp_drop(tp, ECONNRESET); 2223 rstreason = BANDLIM_UNLIMITED; 2224 } else { 2225 tcp_ecn_input_syn_sent(tp, thflags, iptos); 2226 /* Send challenge ACK. */ 2227 tcp_respond(tp, mtod(m, void *), th, m, tp->rcv_nxt, 2228 tp->snd_nxt, TH_ACK); 2229 tp->last_ack_sent = tp->rcv_nxt; 2230 m = NULL; 2231 } 2232 goto drop; 2233 } 2234 2235 /* 2236 * RFC 1323 PAWS: If we have a timestamp reply on this segment 2237 * and it's less than ts_recent, drop it. 2238 */ 2239 if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent && 2240 TSTMP_LT(to.to_tsval, tp->ts_recent)) { 2241 /* Check to see if ts_recent is over 24 days old. */ 2242 if (tcp_ts_getticks() - tp->ts_recent_age > TCP_PAWS_IDLE) { 2243 /* 2244 * Invalidate ts_recent. If this segment updates 2245 * ts_recent, the age will be reset later and ts_recent 2246 * will get a valid value. If it does not, setting 2247 * ts_recent to zero will at least satisfy the 2248 * requirement that zero be placed in the timestamp 2249 * echo reply when ts_recent isn't valid. The 2250 * age isn't reset until we get a valid ts_recent 2251 * because we don't want out-of-order segments to be 2252 * dropped when ts_recent is old. 2253 */ 2254 tp->ts_recent = 0; 2255 } else { 2256 TCPSTAT_INC(tcps_rcvduppack); 2257 TCPSTAT_ADD(tcps_rcvdupbyte, tlen); 2258 TCPSTAT_INC(tcps_pawsdrop); 2259 if (tlen) 2260 goto dropafterack; 2261 goto drop; 2262 } 2263 } 2264 2265 /* 2266 * In the SYN-RECEIVED state, validate that the packet belongs to 2267 * this connection before trimming the data to fit the receive 2268 * window. Check the sequence number versus IRS since we know 2269 * the sequence numbers haven't wrapped. This is a partial fix 2270 * for the "LAND" DoS attack. 2271 */ 2272 if (tp->t_state == TCPS_SYN_RECEIVED && SEQ_LT(th->th_seq, tp->irs)) { 2273 rstreason = BANDLIM_RST_OPENPORT; 2274 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 2275 goto dropwithreset; 2276 } 2277 2278 todrop = tp->rcv_nxt - th->th_seq; 2279 if (todrop > 0) { 2280 if (thflags & TH_SYN) { 2281 thflags &= ~TH_SYN; 2282 th->th_seq++; 2283 if (th->th_urp > 1) 2284 th->th_urp--; 2285 else 2286 thflags &= ~TH_URG; 2287 todrop--; 2288 } 2289 /* 2290 * Following if statement from Stevens, vol. 2, p. 960. 2291 */ 2292 if (todrop > tlen 2293 || (todrop == tlen && (thflags & TH_FIN) == 0)) { 2294 /* 2295 * Any valid FIN must be to the left of the window. 2296 * At this point the FIN must be a duplicate or out 2297 * of sequence; drop it. 2298 */ 2299 thflags &= ~TH_FIN; 2300 2301 /* 2302 * Send an ACK to resynchronize and drop any data. 2303 * But keep on processing for RST or ACK. 2304 */ 2305 tp->t_flags |= TF_ACKNOW; 2306 todrop = tlen; 2307 TCPSTAT_INC(tcps_rcvduppack); 2308 TCPSTAT_ADD(tcps_rcvdupbyte, todrop); 2309 } else { 2310 TCPSTAT_INC(tcps_rcvpartduppack); 2311 TCPSTAT_ADD(tcps_rcvpartdupbyte, todrop); 2312 } 2313 /* 2314 * DSACK - add SACK block for dropped range 2315 */ 2316 if ((todrop > 0) && (tp->t_flags & TF_SACK_PERMIT)) { 2317 tcp_update_sack_list(tp, th->th_seq, 2318 th->th_seq + todrop); 2319 /* 2320 * ACK now, as the next in-sequence segment 2321 * will clear the DSACK block again 2322 */ 2323 tp->t_flags |= TF_ACKNOW; 2324 } 2325 drop_hdrlen += todrop; /* drop from the top afterwards */ 2326 th->th_seq += todrop; 2327 tlen -= todrop; 2328 if (th->th_urp > todrop) 2329 th->th_urp -= todrop; 2330 else { 2331 thflags &= ~TH_URG; 2332 th->th_urp = 0; 2333 } 2334 } 2335 2336 /* 2337 * If new data are received on a connection after the 2338 * user processes are gone, then RST the other end. 2339 */ 2340 if ((tp->t_flags & TF_CLOSED) && tlen) { 2341 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 2342 log(LOG_DEBUG, "%s; %s: %s: Received %d bytes of data " 2343 "after socket was closed, " 2344 "sending RST and removing tcpcb\n", 2345 s, __func__, tcpstates[tp->t_state], tlen); 2346 free(s, M_TCPLOG); 2347 } 2348 tcp_log_end_status(tp, TCP_EI_STATUS_DATA_A_CLOSE); 2349 /* tcp_close will kill the inp pre-log the Reset */ 2350 tcp_log_end_status(tp, TCP_EI_STATUS_SERVER_RST); 2351 tp = tcp_close(tp); 2352 TCPSTAT_INC(tcps_rcvafterclose); 2353 rstreason = BANDLIM_UNLIMITED; 2354 goto dropwithreset; 2355 } 2356 2357 /* 2358 * If segment ends after window, drop trailing data 2359 * (and PUSH and FIN); if nothing left, just ACK. 2360 */ 2361 todrop = (th->th_seq + tlen) - (tp->rcv_nxt + tp->rcv_wnd); 2362 if (todrop > 0) { 2363 TCPSTAT_INC(tcps_rcvpackafterwin); 2364 if (todrop >= tlen) { 2365 TCPSTAT_ADD(tcps_rcvbyteafterwin, tlen); 2366 /* 2367 * If window is closed can only take segments at 2368 * window edge, and have to drop data and PUSH from 2369 * incoming segments. Continue processing, but 2370 * remember to ack. Otherwise, drop segment 2371 * and ack. 2372 */ 2373 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 2374 tp->t_flags |= TF_ACKNOW; 2375 TCPSTAT_INC(tcps_rcvwinprobe); 2376 } else 2377 goto dropafterack; 2378 } else 2379 TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); 2380 m_adj(m, -todrop); 2381 tlen -= todrop; 2382 thflags &= ~(TH_PUSH|TH_FIN); 2383 } 2384 2385 /* 2386 * If last ACK falls within this segment's sequence numbers, 2387 * record its timestamp. 2388 * NOTE: 2389 * 1) That the test incorporates suggestions from the latest 2390 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 2391 * 2) That updating only on newer timestamps interferes with 2392 * our earlier PAWS tests, so this check should be solely 2393 * predicated on the sequence space of this segment. 2394 * 3) That we modify the segment boundary check to be 2395 * Last.ACK.Sent <= SEG.SEQ + SEG.Len 2396 * instead of RFC1323's 2397 * Last.ACK.Sent < SEG.SEQ + SEG.Len, 2398 * This modified check allows us to overcome RFC1323's 2399 * limitations as described in Stevens TCP/IP Illustrated 2400 * Vol. 2 p.869. In such cases, we can still calculate the 2401 * RTT correctly when RCV.NXT == Last.ACK.Sent. 2402 */ 2403 if ((to.to_flags & TOF_TS) != 0 && 2404 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 2405 SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen + 2406 ((thflags & (TH_SYN|TH_FIN)) != 0))) { 2407 tp->ts_recent_age = tcp_ts_getticks(); 2408 tp->ts_recent = to.to_tsval; 2409 } 2410 2411 /* 2412 * If the ACK bit is off: if in SYN-RECEIVED state or SENDSYN 2413 * flag is on (half-synchronized state), then queue data for 2414 * later processing; else drop segment and return. 2415 */ 2416 if ((thflags & TH_ACK) == 0) { 2417 if (tp->t_state == TCPS_SYN_RECEIVED || 2418 (tp->t_flags & TF_NEEDSYN)) { 2419 if (tp->t_state == TCPS_SYN_RECEIVED && 2420 IS_FASTOPEN(tp->t_flags)) { 2421 tp->snd_wnd = tiwin; 2422 cc_conn_init(tp); 2423 } 2424 goto step6; 2425 } else if (tp->t_flags & TF_ACKNOW) 2426 goto dropafterack; 2427 else 2428 goto drop; 2429 } 2430 2431 /* 2432 * Ack processing. 2433 */ 2434 switch (tp->t_state) { 2435 /* 2436 * In SYN_RECEIVED state, the ack ACKs our SYN, so enter 2437 * ESTABLISHED state and continue processing. 2438 * The ACK was checked above. 2439 */ 2440 case TCPS_SYN_RECEIVED: 2441 2442 TCPSTAT_INC(tcps_connects); 2443 if (tp->t_flags & TF_SONOTCONN) { 2444 /* 2445 * Usually SYN_RECEIVED had been created from a LISTEN, 2446 * and solisten_enqueue() has already marked the socket 2447 * layer as connected. If it didn't, which can happen 2448 * only with an accept_filter(9), then the tp is marked 2449 * with TF_SONOTCONN. The other reason for this mark 2450 * to be set is a simultaneous open, a SYN_RECEIVED 2451 * that had been created from SYN_SENT. 2452 */ 2453 tp->t_flags &= ~TF_SONOTCONN; 2454 soisconnected(so); 2455 } 2456 /* Do window scaling? */ 2457 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2458 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2459 tp->rcv_scale = tp->request_r_scale; 2460 } 2461 tp->snd_wnd = tiwin; 2462 /* 2463 * Make transitions: 2464 * SYN-RECEIVED -> ESTABLISHED 2465 * SYN-RECEIVED* -> FIN-WAIT-1 2466 */ 2467 tp->t_starttime = ticks; 2468 if (IS_FASTOPEN(tp->t_flags) && tp->t_tfo_pending) { 2469 tcp_fastopen_decrement_counter(tp->t_tfo_pending); 2470 tp->t_tfo_pending = NULL; 2471 } 2472 if (tp->t_flags & TF_NEEDFIN) { 2473 tp->t_acktime = ticks; 2474 tcp_state_change(tp, TCPS_FIN_WAIT_1); 2475 tp->t_flags &= ~TF_NEEDFIN; 2476 } else { 2477 tcp_state_change(tp, TCPS_ESTABLISHED); 2478 TCP_PROBE5(accept__established, NULL, tp, 2479 m, tp, th); 2480 /* 2481 * TFO connections call cc_conn_init() during SYN 2482 * processing. Calling it again here for such 2483 * connections is not harmless as it would undo the 2484 * snd_cwnd reduction that occurs when a TFO SYN|ACK 2485 * is retransmitted. 2486 */ 2487 if (!IS_FASTOPEN(tp->t_flags)) 2488 cc_conn_init(tp); 2489 tcp_timer_activate(tp, TT_KEEP, TP_KEEPIDLE(tp)); 2490 } 2491 /* 2492 * Account for the ACK of our SYN prior to 2493 * regular ACK processing below, except for 2494 * simultaneous SYN, which is handled later. 2495 */ 2496 if (SEQ_GT(th->th_ack, tp->snd_una) && !(tp->t_flags & TF_NEEDSYN)) 2497 incforsyn = 1; 2498 /* 2499 * If segment contains data or ACK, will call tcp_reass() 2500 * later; if not, do so now to pass queued data to user. 2501 */ 2502 if (tlen == 0 && (thflags & TH_FIN) == 0) { 2503 (void) tcp_reass(tp, (struct tcphdr *)0, NULL, 0, 2504 (struct mbuf *)0); 2505 tcp_handle_wakeup(tp); 2506 } 2507 tp->snd_wl1 = th->th_seq - 1; 2508 /* FALLTHROUGH */ 2509 2510 /* 2511 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 2512 * ACKs. If the ack is in the range 2513 * tp->snd_una < th->th_ack <= tp->snd_max 2514 * then advance tp->snd_una to th->th_ack and drop 2515 * data from the retransmission queue. If this ACK reflects 2516 * more up to date window information we update our window information. 2517 */ 2518 case TCPS_ESTABLISHED: 2519 case TCPS_FIN_WAIT_1: 2520 case TCPS_FIN_WAIT_2: 2521 case TCPS_CLOSE_WAIT: 2522 case TCPS_CLOSING: 2523 case TCPS_LAST_ACK: 2524 if (SEQ_GT(th->th_ack, tp->snd_max)) { 2525 TCPSTAT_INC(tcps_rcvacktoomuch); 2526 goto dropafterack; 2527 } 2528 if (tcp_is_sack_recovery(tp, &to)) { 2529 if (((sack_changed = tcp_sack_doack(tp, &to, th->th_ack)) != 0) && 2530 (tp->t_flags & TF_LRD)) { 2531 tcp_sack_lost_retransmission(tp, th); 2532 } 2533 } else 2534 /* 2535 * Reset the value so that previous (valid) value 2536 * from the last ack with SACK doesn't get used. 2537 */ 2538 tp->sackhint.sacked_bytes = 0; 2539 2540 #ifdef TCP_HHOOK 2541 /* Run HHOOK_TCP_ESTABLISHED_IN helper hooks. */ 2542 hhook_run_tcp_est_in(tp, th, &to); 2543 #endif 2544 2545 if (SEQ_LEQ(th->th_ack, tp->snd_una)) { 2546 maxseg = tcp_maxseg(tp); 2547 if (tlen == 0 && 2548 (tiwin == tp->snd_wnd || 2549 (tp->t_flags & TF_SACK_PERMIT))) { 2550 /* 2551 * If this is the first time we've seen a 2552 * FIN from the remote, this is not a 2553 * duplicate and it needs to be processed 2554 * normally. This happens during a 2555 * simultaneous close. 2556 */ 2557 if ((thflags & TH_FIN) && 2558 (TCPS_HAVERCVDFIN(tp->t_state) == 0)) { 2559 tp->t_dupacks = 0; 2560 break; 2561 } 2562 TCPSTAT_INC(tcps_rcvdupack); 2563 /* 2564 * If we have outstanding data (other than 2565 * a window probe), this is a completely 2566 * duplicate ack (ie, window info didn't 2567 * change and FIN isn't set), 2568 * the ack is the biggest we've 2569 * seen and we've seen exactly our rexmt 2570 * threshold of them, assume a packet 2571 * has been dropped and retransmit it. 2572 * Kludge snd_nxt & the congestion 2573 * window so we send only this one 2574 * packet. 2575 * 2576 * We know we're losing at the current 2577 * window size so do congestion avoidance 2578 * (set ssthresh to half the current window 2579 * and pull our congestion window back to 2580 * the new ssthresh). 2581 * 2582 * Dup acks mean that packets have left the 2583 * network (they're now cached at the receiver) 2584 * so bump cwnd by the amount in the receiver 2585 * to keep a constant cwnd packets in the 2586 * network. 2587 * 2588 * When using TCP ECN, notify the peer that 2589 * we reduced the cwnd. 2590 */ 2591 /* 2592 * Following 2 kinds of acks should not affect 2593 * dupack counting: 2594 * 1) Old acks 2595 * 2) Acks with SACK but without any new SACK 2596 * information in them. These could result from 2597 * any anomaly in the network like a switch 2598 * duplicating packets or a possible DoS attack. 2599 */ 2600 if (th->th_ack != tp->snd_una || 2601 (tcp_is_sack_recovery(tp, &to) && 2602 !sack_changed)) 2603 break; 2604 else if (!tcp_timer_active(tp, TT_REXMT)) 2605 tp->t_dupacks = 0; 2606 else if (++tp->t_dupacks > tcprexmtthresh || 2607 IN_FASTRECOVERY(tp->t_flags)) { 2608 cc_ack_received(tp, th, nsegs, 2609 CC_DUPACK); 2610 if (V_tcp_do_prr && 2611 IN_FASTRECOVERY(tp->t_flags)) { 2612 tcp_do_prr_ack(tp, th, &to); 2613 } else if (tcp_is_sack_recovery(tp, &to) && 2614 IN_FASTRECOVERY(tp->t_flags)) { 2615 int awnd; 2616 2617 /* 2618 * Compute the amount of data in flight first. 2619 * We can inject new data into the pipe iff 2620 * we have less than 1/2 the original window's 2621 * worth of data in flight. 2622 */ 2623 if (V_tcp_do_newsack) 2624 awnd = tcp_compute_pipe(tp); 2625 else 2626 awnd = (tp->snd_nxt - tp->snd_fack) + 2627 tp->sackhint.sack_bytes_rexmit; 2628 2629 if (awnd < tp->snd_ssthresh) { 2630 tp->snd_cwnd += maxseg; 2631 if (tp->snd_cwnd > tp->snd_ssthresh) 2632 tp->snd_cwnd = tp->snd_ssthresh; 2633 } 2634 } else 2635 tp->snd_cwnd += maxseg; 2636 (void) tcp_output(tp); 2637 goto drop; 2638 } else if (tp->t_dupacks == tcprexmtthresh || 2639 (tp->t_flags & TF_SACK_PERMIT && 2640 V_tcp_do_newsack && 2641 tp->sackhint.sacked_bytes > 2642 (tcprexmtthresh - 1) * maxseg)) { 2643 enter_recovery: 2644 /* 2645 * Above is the RFC6675 trigger condition of 2646 * more than (dupthresh-1)*maxseg sacked data. 2647 * If the count of holes in the 2648 * scoreboard is >= dupthresh, we could 2649 * also enter loss recovery, but don't 2650 * have that value readily available. 2651 */ 2652 tp->t_dupacks = tcprexmtthresh; 2653 tcp_seq onxt = tp->snd_nxt; 2654 2655 /* 2656 * If we're doing sack, or prr, check 2657 * to see if we're already in sack 2658 * recovery. If we're not doing sack, 2659 * check to see if we're in newreno 2660 * recovery. 2661 */ 2662 if (V_tcp_do_prr || 2663 (tp->t_flags & TF_SACK_PERMIT)) { 2664 if (IN_FASTRECOVERY(tp->t_flags)) { 2665 tp->t_dupacks = 0; 2666 break; 2667 } 2668 } else { 2669 if (SEQ_LEQ(th->th_ack, 2670 tp->snd_recover)) { 2671 tp->t_dupacks = 0; 2672 break; 2673 } 2674 } 2675 /* Congestion signal before ack. */ 2676 cc_cong_signal(tp, th, CC_NDUPACK); 2677 cc_ack_received(tp, th, nsegs, 2678 CC_DUPACK); 2679 tcp_timer_activate(tp, TT_REXMT, 0); 2680 tp->t_rtttime = 0; 2681 if (V_tcp_do_prr) { 2682 /* 2683 * snd_ssthresh is already updated by 2684 * cc_cong_signal. 2685 */ 2686 if (tcp_is_sack_recovery(tp, &to)) { 2687 tp->sackhint.prr_delivered = 2688 tp->sackhint.sacked_bytes; 2689 } else { 2690 tp->sackhint.prr_delivered = 2691 imin(tp->snd_max - tp->snd_una, 2692 imin(INT_MAX / 65536, 2693 tp->t_dupacks) * maxseg); 2694 } 2695 tp->sackhint.recover_fs = max(1, 2696 tp->snd_nxt - tp->snd_una); 2697 } 2698 if (tcp_is_sack_recovery(tp, &to)) { 2699 TCPSTAT_INC( 2700 tcps_sack_recovery_episode); 2701 tp->snd_recover = tp->snd_nxt; 2702 tp->snd_cwnd = maxseg; 2703 (void) tcp_output(tp); 2704 if (SEQ_GT(th->th_ack, tp->snd_una)) 2705 goto resume_partialack; 2706 goto drop; 2707 } 2708 tp->snd_nxt = th->th_ack; 2709 tp->snd_cwnd = maxseg; 2710 (void) tcp_output(tp); 2711 KASSERT(tp->snd_limited <= 2, 2712 ("%s: tp->snd_limited too big", 2713 __func__)); 2714 tp->snd_cwnd = tp->snd_ssthresh + 2715 maxseg * 2716 (tp->t_dupacks - tp->snd_limited); 2717 if (SEQ_GT(onxt, tp->snd_nxt)) 2718 tp->snd_nxt = onxt; 2719 goto drop; 2720 } else if (V_tcp_do_rfc3042) { 2721 /* 2722 * Process first and second duplicate 2723 * ACKs. Each indicates a segment 2724 * leaving the network, creating room 2725 * for more. Make sure we can send a 2726 * packet on reception of each duplicate 2727 * ACK by increasing snd_cwnd by one 2728 * segment. Restore the original 2729 * snd_cwnd after packet transmission. 2730 */ 2731 cc_ack_received(tp, th, nsegs, 2732 CC_DUPACK); 2733 uint32_t oldcwnd = tp->snd_cwnd; 2734 tcp_seq oldsndmax = tp->snd_max; 2735 u_int sent; 2736 int avail; 2737 2738 KASSERT(tp->t_dupacks == 1 || 2739 tp->t_dupacks == 2, 2740 ("%s: dupacks not 1 or 2", 2741 __func__)); 2742 if (tp->t_dupacks == 1) 2743 tp->snd_limited = 0; 2744 tp->snd_cwnd = 2745 (tp->snd_nxt - tp->snd_una) + 2746 (tp->t_dupacks - tp->snd_limited) * 2747 maxseg; 2748 /* 2749 * Only call tcp_output when there 2750 * is new data available to be sent 2751 * or we need to send an ACK. 2752 */ 2753 SOCKBUF_LOCK(&so->so_snd); 2754 avail = sbavail(&so->so_snd) - 2755 (tp->snd_nxt - tp->snd_una); 2756 SOCKBUF_UNLOCK(&so->so_snd); 2757 if (avail > 0 || tp->t_flags & TF_ACKNOW) 2758 (void) tcp_output(tp); 2759 sent = tp->snd_max - oldsndmax; 2760 if (sent > maxseg) { 2761 KASSERT((tp->t_dupacks == 2 && 2762 tp->snd_limited == 0) || 2763 (sent == maxseg + 1 && 2764 tp->t_flags & TF_SENTFIN), 2765 ("%s: sent too much", 2766 __func__)); 2767 tp->snd_limited = 2; 2768 } else if (sent > 0) 2769 ++tp->snd_limited; 2770 tp->snd_cwnd = oldcwnd; 2771 goto drop; 2772 } 2773 } 2774 break; 2775 } else { 2776 /* 2777 * This ack is advancing the left edge, reset the 2778 * counter. 2779 */ 2780 tp->t_dupacks = 0; 2781 /* 2782 * If this ack also has new SACK info, increment the 2783 * counter as per rfc6675. The variable 2784 * sack_changed tracks all changes to the SACK 2785 * scoreboard, including when partial ACKs without 2786 * SACK options are received, and clear the scoreboard 2787 * from the left side. Such partial ACKs should not be 2788 * counted as dupacks here. 2789 */ 2790 if (tcp_is_sack_recovery(tp, &to) && 2791 sack_changed) { 2792 tp->t_dupacks++; 2793 /* limit overhead by setting maxseg last */ 2794 if (!IN_FASTRECOVERY(tp->t_flags) && 2795 (tp->sackhint.sacked_bytes > 2796 ((tcprexmtthresh - 1) * 2797 (maxseg = tcp_maxseg(tp))))) { 2798 goto enter_recovery; 2799 } 2800 } 2801 } 2802 2803 resume_partialack: 2804 KASSERT(SEQ_GT(th->th_ack, tp->snd_una), 2805 ("%s: th_ack <= snd_una", __func__)); 2806 2807 /* 2808 * If the congestion window was inflated to account 2809 * for the other side's cached packets, retract it. 2810 */ 2811 if (IN_FASTRECOVERY(tp->t_flags)) { 2812 if (SEQ_LT(th->th_ack, tp->snd_recover)) { 2813 if (tp->t_flags & TF_SACK_PERMIT) 2814 if (V_tcp_do_prr && to.to_flags & TOF_SACK) { 2815 tcp_timer_activate(tp, TT_REXMT, 0); 2816 tp->t_rtttime = 0; 2817 tcp_do_prr_ack(tp, th, &to); 2818 tp->t_flags |= TF_ACKNOW; 2819 (void) tcp_output(tp); 2820 } else 2821 tcp_sack_partialack(tp, th); 2822 else 2823 tcp_newreno_partial_ack(tp, th); 2824 } else 2825 cc_post_recovery(tp, th); 2826 } else if (IN_CONGRECOVERY(tp->t_flags)) { 2827 if (SEQ_LT(th->th_ack, tp->snd_recover)) { 2828 if (V_tcp_do_prr) { 2829 tp->sackhint.delivered_data = BYTES_THIS_ACK(tp, th); 2830 tp->snd_fack = th->th_ack; 2831 tcp_do_prr_ack(tp, th, &to); 2832 (void) tcp_output(tp); 2833 } 2834 } else 2835 cc_post_recovery(tp, th); 2836 } 2837 /* 2838 * If we reach this point, ACK is not a duplicate, 2839 * i.e., it ACKs something we sent. 2840 */ 2841 if (tp->t_flags & TF_NEEDSYN) { 2842 /* 2843 * T/TCP: Connection was half-synchronized, and our 2844 * SYN has been ACK'd (so connection is now fully 2845 * synchronized). Go to non-starred state, 2846 * increment snd_una for ACK of SYN, and check if 2847 * we can do window scaling. 2848 */ 2849 tp->t_flags &= ~TF_NEEDSYN; 2850 tp->snd_una++; 2851 /* Do window scaling? */ 2852 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2853 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2854 tp->rcv_scale = tp->request_r_scale; 2855 /* Send window already scaled. */ 2856 } 2857 } 2858 2859 process_ACK: 2860 INP_WLOCK_ASSERT(tp->t_inpcb); 2861 2862 /* 2863 * Adjust for the SYN bit in sequence space, 2864 * but don't account for it in cwnd calculations. 2865 * This is for the SYN_RECEIVED, non-simultaneous 2866 * SYN case. SYN_SENT and simultaneous SYN are 2867 * treated elsewhere. 2868 */ 2869 if (incforsyn) 2870 tp->snd_una++; 2871 acked = BYTES_THIS_ACK(tp, th); 2872 KASSERT(acked >= 0, ("%s: acked unexepectedly negative " 2873 "(tp->snd_una=%u, th->th_ack=%u, tp=%p, m=%p)", __func__, 2874 tp->snd_una, th->th_ack, tp, m)); 2875 TCPSTAT_ADD(tcps_rcvackpack, nsegs); 2876 TCPSTAT_ADD(tcps_rcvackbyte, acked); 2877 2878 /* 2879 * If we just performed our first retransmit, and the ACK 2880 * arrives within our recovery window, then it was a mistake 2881 * to do the retransmit in the first place. Recover our 2882 * original cwnd and ssthresh, and proceed to transmit where 2883 * we left off. 2884 */ 2885 if (tp->t_rxtshift == 1 && 2886 tp->t_flags & TF_PREVVALID && 2887 tp->t_badrxtwin != 0 && 2888 to.to_flags & TOF_TS && 2889 to.to_tsecr != 0 && 2890 TSTMP_LT(to.to_tsecr, tp->t_badrxtwin)) 2891 cc_cong_signal(tp, th, CC_RTO_ERR); 2892 2893 /* 2894 * If we have a timestamp reply, update smoothed 2895 * round trip time. If no timestamp is present but 2896 * transmit timer is running and timed sequence 2897 * number was acked, update smoothed round trip time. 2898 * Since we now have an rtt measurement, cancel the 2899 * timer backoff (cf., Phil Karn's retransmit alg.). 2900 * Recompute the initial retransmit timer. 2901 * 2902 * Some boxes send broken timestamp replies 2903 * during the SYN+ACK phase, ignore 2904 * timestamps of 0 or we could calculate a 2905 * huge RTT and blow up the retransmit timer. 2906 */ 2907 if ((to.to_flags & TOF_TS) != 0 && to.to_tsecr) { 2908 uint32_t t; 2909 2910 t = tcp_ts_getticks() - to.to_tsecr; 2911 if (!tp->t_rttlow || tp->t_rttlow > t) 2912 tp->t_rttlow = t; 2913 tcp_xmit_timer(tp, TCP_TS_TO_TICKS(t) + 1); 2914 } else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) { 2915 if (!tp->t_rttlow || tp->t_rttlow > ticks - tp->t_rtttime) 2916 tp->t_rttlow = ticks - tp->t_rtttime; 2917 tcp_xmit_timer(tp, ticks - tp->t_rtttime); 2918 } 2919 2920 SOCKBUF_LOCK(&so->so_snd); 2921 /* 2922 * Clear t_acktime if remote side has ACKd all data in the 2923 * socket buffer and FIN (if applicable). 2924 * Otherwise, update t_acktime if we received a sufficiently 2925 * large ACK. 2926 */ 2927 if ((tp->t_state <= TCPS_CLOSE_WAIT && 2928 acked == sbavail(&so->so_snd)) || 2929 acked > sbavail(&so->so_snd)) 2930 tp->t_acktime = 0; 2931 else if (acked > 1) 2932 tp->t_acktime = ticks; 2933 2934 /* 2935 * If all outstanding data is acked, stop retransmit 2936 * timer and remember to restart (more output or persist). 2937 * If there is more data to be acked, restart retransmit 2938 * timer, using current (possibly backed-off) value. 2939 */ 2940 if (th->th_ack == tp->snd_max) { 2941 tcp_timer_activate(tp, TT_REXMT, 0); 2942 needoutput = 1; 2943 } else if (!tcp_timer_active(tp, TT_PERSIST)) 2944 tcp_timer_activate(tp, TT_REXMT, TP_RXTCUR(tp)); 2945 2946 /* 2947 * If no data (only SYN) was ACK'd, 2948 * skip rest of ACK processing. 2949 */ 2950 if (acked == 0) { 2951 SOCKBUF_UNLOCK(&so->so_snd); 2952 goto step6; 2953 } 2954 2955 /* 2956 * Let the congestion control algorithm update congestion 2957 * control related information. This typically means increasing 2958 * the congestion window. 2959 */ 2960 cc_ack_received(tp, th, nsegs, CC_ACK); 2961 2962 if (acked > sbavail(&so->so_snd)) { 2963 if (tp->snd_wnd >= sbavail(&so->so_snd)) 2964 tp->snd_wnd -= sbavail(&so->so_snd); 2965 else 2966 tp->snd_wnd = 0; 2967 mfree = sbcut_locked(&so->so_snd, 2968 (int)sbavail(&so->so_snd)); 2969 ourfinisacked = 1; 2970 } else { 2971 mfree = sbcut_locked(&so->so_snd, acked); 2972 if (tp->snd_wnd >= (uint32_t) acked) 2973 tp->snd_wnd -= acked; 2974 else 2975 tp->snd_wnd = 0; 2976 ourfinisacked = 0; 2977 } 2978 /* NB: sowwakeup_locked() does an implicit unlock. */ 2979 sowwakeup_locked(so); 2980 m_freem(mfree); 2981 /* Detect una wraparound. */ 2982 if (!IN_RECOVERY(tp->t_flags) && 2983 SEQ_GT(tp->snd_una, tp->snd_recover) && 2984 SEQ_LEQ(th->th_ack, tp->snd_recover)) 2985 tp->snd_recover = th->th_ack - 1; 2986 /* XXXLAS: Can this be moved up into cc_post_recovery? */ 2987 if (IN_RECOVERY(tp->t_flags) && 2988 SEQ_GEQ(th->th_ack, tp->snd_recover)) { 2989 EXIT_RECOVERY(tp->t_flags); 2990 } 2991 tp->snd_una = th->th_ack; 2992 if (tp->t_flags & TF_SACK_PERMIT) { 2993 if (SEQ_GT(tp->snd_una, tp->snd_recover)) 2994 tp->snd_recover = tp->snd_una; 2995 } 2996 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2997 tp->snd_nxt = tp->snd_una; 2998 2999 switch (tp->t_state) { 3000 /* 3001 * In FIN_WAIT_1 STATE in addition to the processing 3002 * for the ESTABLISHED state if our FIN is now acknowledged 3003 * then enter FIN_WAIT_2. 3004 */ 3005 case TCPS_FIN_WAIT_1: 3006 if (ourfinisacked) { 3007 /* 3008 * If we can't receive any more 3009 * data, then closing user can proceed. 3010 * Starting the timer is contrary to the 3011 * specification, but if we don't get a FIN 3012 * we'll hang forever. 3013 */ 3014 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 3015 soisdisconnected(so); 3016 tcp_timer_activate(tp, TT_2MSL, 3017 (tcp_fast_finwait2_recycle ? 3018 tcp_finwait2_timeout : 3019 TP_MAXIDLE(tp))); 3020 } 3021 tcp_state_change(tp, TCPS_FIN_WAIT_2); 3022 } 3023 break; 3024 3025 /* 3026 * In CLOSING STATE in addition to the processing for 3027 * the ESTABLISHED state if the ACK acknowledges our FIN 3028 * then enter the TIME-WAIT state, otherwise ignore 3029 * the segment. 3030 */ 3031 case TCPS_CLOSING: 3032 if (ourfinisacked) { 3033 tcp_twstart(tp); 3034 m_freem(m); 3035 return; 3036 } 3037 break; 3038 3039 /* 3040 * In LAST_ACK, we may still be waiting for data to drain 3041 * and/or to be acked, as well as for the ack of our FIN. 3042 * If our FIN is now acknowledged, delete the TCB, 3043 * enter the closed state and return. 3044 */ 3045 case TCPS_LAST_ACK: 3046 if (ourfinisacked) { 3047 tp = tcp_close(tp); 3048 goto drop; 3049 } 3050 break; 3051 } 3052 } 3053 3054 step6: 3055 INP_WLOCK_ASSERT(tp->t_inpcb); 3056 3057 /* 3058 * Update window information. 3059 * Don't look at window if no ACK: TAC's send garbage on first SYN. 3060 */ 3061 if ((thflags & TH_ACK) && 3062 (SEQ_LT(tp->snd_wl1, th->th_seq) || 3063 (tp->snd_wl1 == th->th_seq && (SEQ_LT(tp->snd_wl2, th->th_ack) || 3064 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))) { 3065 /* keep track of pure window updates */ 3066 if (tlen == 0 && 3067 tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) 3068 TCPSTAT_INC(tcps_rcvwinupd); 3069 tp->snd_wnd = tiwin; 3070 tp->snd_wl1 = th->th_seq; 3071 tp->snd_wl2 = th->th_ack; 3072 if (tp->snd_wnd > tp->max_sndwnd) 3073 tp->max_sndwnd = tp->snd_wnd; 3074 needoutput = 1; 3075 } 3076 3077 /* 3078 * Process segments with URG. 3079 */ 3080 if ((thflags & TH_URG) && th->th_urp && 3081 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3082 /* 3083 * This is a kludge, but if we receive and accept 3084 * random urgent pointers, we'll crash in 3085 * soreceive. It's hard to imagine someone 3086 * actually wanting to send this much urgent data. 3087 */ 3088 SOCKBUF_LOCK(&so->so_rcv); 3089 if (th->th_urp + sbavail(&so->so_rcv) > sb_max) { 3090 th->th_urp = 0; /* XXX */ 3091 thflags &= ~TH_URG; /* XXX */ 3092 SOCKBUF_UNLOCK(&so->so_rcv); /* XXX */ 3093 goto dodata; /* XXX */ 3094 } 3095 /* 3096 * If this segment advances the known urgent pointer, 3097 * then mark the data stream. This should not happen 3098 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 3099 * a FIN has been received from the remote side. 3100 * In these states we ignore the URG. 3101 * 3102 * According to RFC961 (Assigned Protocols), 3103 * the urgent pointer points to the last octet 3104 * of urgent data. We continue, however, 3105 * to consider it to indicate the first octet 3106 * of data past the urgent section as the original 3107 * spec states (in one of two places). 3108 */ 3109 if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) { 3110 tp->rcv_up = th->th_seq + th->th_urp; 3111 so->so_oobmark = sbavail(&so->so_rcv) + 3112 (tp->rcv_up - tp->rcv_nxt) - 1; 3113 if (so->so_oobmark == 0) 3114 so->so_rcv.sb_state |= SBS_RCVATMARK; 3115 sohasoutofband(so); 3116 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); 3117 } 3118 SOCKBUF_UNLOCK(&so->so_rcv); 3119 /* 3120 * Remove out of band data so doesn't get presented to user. 3121 * This can happen independent of advancing the URG pointer, 3122 * but if two URG's are pending at once, some out-of-band 3123 * data may creep in... ick. 3124 */ 3125 if (th->th_urp <= (uint32_t)tlen && 3126 !(so->so_options & SO_OOBINLINE)) { 3127 /* hdr drop is delayed */ 3128 tcp_pulloutofband(so, th, m, drop_hdrlen); 3129 } 3130 } else { 3131 /* 3132 * If no out of band data is expected, 3133 * pull receive urgent pointer along 3134 * with the receive window. 3135 */ 3136 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) 3137 tp->rcv_up = tp->rcv_nxt; 3138 } 3139 dodata: /* XXX */ 3140 INP_WLOCK_ASSERT(tp->t_inpcb); 3141 3142 /* 3143 * Process the segment text, merging it into the TCP sequencing queue, 3144 * and arranging for acknowledgment of receipt if necessary. 3145 * This process logically involves adjusting tp->rcv_wnd as data 3146 * is presented to the user (this happens in tcp_usrreq.c, 3147 * case PRU_RCVD). If a FIN has already been received on this 3148 * connection then we just ignore the text. 3149 */ 3150 tfo_syn = ((tp->t_state == TCPS_SYN_RECEIVED) && 3151 IS_FASTOPEN(tp->t_flags)); 3152 if ((tlen || (thflags & TH_FIN) || (tfo_syn && tlen > 0)) && 3153 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3154 tcp_seq save_start = th->th_seq; 3155 tcp_seq save_rnxt = tp->rcv_nxt; 3156 int save_tlen = tlen; 3157 m_adj(m, drop_hdrlen); /* delayed header drop */ 3158 /* 3159 * Insert segment which includes th into TCP reassembly queue 3160 * with control block tp. Set thflags to whether reassembly now 3161 * includes a segment with FIN. This handles the common case 3162 * inline (segment is the next to be received on an established 3163 * connection, and the queue is empty), avoiding linkage into 3164 * and removal from the queue and repetition of various 3165 * conversions. 3166 * Set DELACK for segments received in order, but ack 3167 * immediately when segments are out of order (so 3168 * fast retransmit can work). 3169 */ 3170 if (th->th_seq == tp->rcv_nxt && 3171 SEGQ_EMPTY(tp) && 3172 (TCPS_HAVEESTABLISHED(tp->t_state) || 3173 tfo_syn)) { 3174 if (DELAY_ACK(tp, tlen) || tfo_syn) 3175 tp->t_flags |= TF_DELACK; 3176 else 3177 tp->t_flags |= TF_ACKNOW; 3178 tp->rcv_nxt += tlen; 3179 if (tlen && 3180 ((tp->t_flags2 & TF2_FBYTES_COMPLETE) == 0) && 3181 (tp->t_fbyte_in == 0)) { 3182 tp->t_fbyte_in = ticks; 3183 if (tp->t_fbyte_in == 0) 3184 tp->t_fbyte_in = 1; 3185 if (tp->t_fbyte_out && tp->t_fbyte_in) 3186 tp->t_flags2 |= TF2_FBYTES_COMPLETE; 3187 } 3188 thflags = tcp_get_flags(th) & TH_FIN; 3189 TCPSTAT_INC(tcps_rcvpack); 3190 TCPSTAT_ADD(tcps_rcvbyte, tlen); 3191 SOCKBUF_LOCK(&so->so_rcv); 3192 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) 3193 m_freem(m); 3194 else 3195 sbappendstream_locked(&so->so_rcv, m, 0); 3196 tp->t_flags |= TF_WAKESOR; 3197 } else { 3198 /* 3199 * XXX: Due to the header drop above "th" is 3200 * theoretically invalid by now. Fortunately 3201 * m_adj() doesn't actually frees any mbufs 3202 * when trimming from the head. 3203 */ 3204 tcp_seq temp = save_start; 3205 3206 thflags = tcp_reass(tp, th, &temp, &tlen, m); 3207 tp->t_flags |= TF_ACKNOW; 3208 } 3209 if ((tp->t_flags & TF_SACK_PERMIT) && 3210 (save_tlen > 0) && 3211 TCPS_HAVEESTABLISHED(tp->t_state)) { 3212 if ((tlen == 0) && (SEQ_LT(save_start, save_rnxt))) { 3213 /* 3214 * DSACK actually handled in the fastpath 3215 * above. 3216 */ 3217 tcp_update_sack_list(tp, save_start, 3218 save_start + save_tlen); 3219 } else if ((tlen > 0) && SEQ_GT(tp->rcv_nxt, save_rnxt)) { 3220 if ((tp->rcv_numsacks >= 1) && 3221 (tp->sackblks[0].end == save_start)) { 3222 /* 3223 * Partial overlap, recorded at todrop 3224 * above. 3225 */ 3226 tcp_update_sack_list(tp, 3227 tp->sackblks[0].start, 3228 tp->sackblks[0].end); 3229 } else { 3230 tcp_update_dsack_list(tp, save_start, 3231 save_start + save_tlen); 3232 } 3233 } else if (tlen >= save_tlen) { 3234 /* Update of sackblks. */ 3235 tcp_update_dsack_list(tp, save_start, 3236 save_start + save_tlen); 3237 } else if (tlen > 0) { 3238 tcp_update_dsack_list(tp, save_start, 3239 save_start + tlen); 3240 } 3241 } 3242 tcp_handle_wakeup(tp); 3243 #if 0 3244 /* 3245 * Note the amount of data that peer has sent into 3246 * our window, in order to estimate the sender's 3247 * buffer size. 3248 * XXX: Unused. 3249 */ 3250 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt)) 3251 len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); 3252 else 3253 len = so->so_rcv.sb_hiwat; 3254 #endif 3255 } else { 3256 m_freem(m); 3257 thflags &= ~TH_FIN; 3258 } 3259 3260 /* 3261 * If FIN is received ACK the FIN and let the user know 3262 * that the connection is closing. 3263 */ 3264 if (thflags & TH_FIN) { 3265 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3266 /* The socket upcall is handled by socantrcvmore. */ 3267 socantrcvmore(so); 3268 /* 3269 * If connection is half-synchronized 3270 * (ie NEEDSYN flag on) then delay ACK, 3271 * so it may be piggybacked when SYN is sent. 3272 * Otherwise, since we received a FIN then no 3273 * more input can be expected, send ACK now. 3274 */ 3275 if (tp->t_flags & TF_NEEDSYN) 3276 tp->t_flags |= TF_DELACK; 3277 else 3278 tp->t_flags |= TF_ACKNOW; 3279 tp->rcv_nxt++; 3280 } 3281 switch (tp->t_state) { 3282 /* 3283 * In SYN_RECEIVED and ESTABLISHED STATES 3284 * enter the CLOSE_WAIT state. 3285 */ 3286 case TCPS_SYN_RECEIVED: 3287 tp->t_starttime = ticks; 3288 /* FALLTHROUGH */ 3289 case TCPS_ESTABLISHED: 3290 tcp_state_change(tp, TCPS_CLOSE_WAIT); 3291 break; 3292 3293 /* 3294 * If still in FIN_WAIT_1 STATE FIN has not been acked so 3295 * enter the CLOSING state. 3296 */ 3297 case TCPS_FIN_WAIT_1: 3298 tcp_state_change(tp, TCPS_CLOSING); 3299 break; 3300 3301 /* 3302 * In FIN_WAIT_2 state enter the TIME_WAIT state, 3303 * starting the time-wait timer, turning off the other 3304 * standard timers. 3305 */ 3306 case TCPS_FIN_WAIT_2: 3307 tcp_twstart(tp); 3308 return; 3309 } 3310 } 3311 #ifdef TCPDEBUG 3312 if (so->so_options & SO_DEBUG) 3313 tcp_trace(TA_INPUT, ostate, tp, (void *)tcp_saveipgen, 3314 &tcp_savetcp, 0); 3315 #endif 3316 TCP_PROBE3(debug__input, tp, th, m); 3317 3318 /* 3319 * Return any desired output. 3320 */ 3321 if (needoutput || (tp->t_flags & TF_ACKNOW)) 3322 (void) tcp_output(tp); 3323 3324 check_delack: 3325 INP_WLOCK_ASSERT(tp->t_inpcb); 3326 3327 if (tp->t_flags & TF_DELACK) { 3328 tp->t_flags &= ~TF_DELACK; 3329 tcp_timer_activate(tp, TT_DELACK, tcp_delacktime); 3330 } 3331 INP_WUNLOCK(tp->t_inpcb); 3332 return; 3333 3334 dropafterack: 3335 /* 3336 * Generate an ACK dropping incoming segment if it occupies 3337 * sequence space, where the ACK reflects our state. 3338 * 3339 * We can now skip the test for the RST flag since all 3340 * paths to this code happen after packets containing 3341 * RST have been dropped. 3342 * 3343 * In the SYN-RECEIVED state, don't send an ACK unless the 3344 * segment we received passes the SYN-RECEIVED ACK test. 3345 * If it fails send a RST. This breaks the loop in the 3346 * "LAND" DoS attack, and also prevents an ACK storm 3347 * between two listening ports that have been sent forged 3348 * SYN segments, each with the source address of the other. 3349 */ 3350 if (tp->t_state == TCPS_SYN_RECEIVED && (thflags & TH_ACK) && 3351 (SEQ_GT(tp->snd_una, th->th_ack) || 3352 SEQ_GT(th->th_ack, tp->snd_max)) ) { 3353 rstreason = BANDLIM_RST_OPENPORT; 3354 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 3355 goto dropwithreset; 3356 } 3357 #ifdef TCPDEBUG 3358 if (so->so_options & SO_DEBUG) 3359 tcp_trace(TA_DROP, ostate, tp, (void *)tcp_saveipgen, 3360 &tcp_savetcp, 0); 3361 #endif 3362 TCP_PROBE3(debug__input, tp, th, m); 3363 tp->t_flags |= TF_ACKNOW; 3364 (void) tcp_output(tp); 3365 INP_WUNLOCK(tp->t_inpcb); 3366 m_freem(m); 3367 return; 3368 3369 dropwithreset: 3370 if (tp != NULL) { 3371 tcp_dropwithreset(m, th, tp, tlen, rstreason); 3372 INP_WUNLOCK(tp->t_inpcb); 3373 } else 3374 tcp_dropwithreset(m, th, NULL, tlen, rstreason); 3375 return; 3376 3377 drop: 3378 /* 3379 * Drop space held by incoming segment and return. 3380 */ 3381 #ifdef TCPDEBUG 3382 if (tp == NULL || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) 3383 tcp_trace(TA_DROP, ostate, tp, (void *)tcp_saveipgen, 3384 &tcp_savetcp, 0); 3385 #endif 3386 TCP_PROBE3(debug__input, tp, th, m); 3387 if (tp != NULL) { 3388 INP_WUNLOCK(tp->t_inpcb); 3389 } 3390 m_freem(m); 3391 } 3392 3393 /* 3394 * Issue RST and make ACK acceptable to originator of segment. 3395 * The mbuf must still include the original packet header. 3396 * tp may be NULL. 3397 */ 3398 void 3399 tcp_dropwithreset(struct mbuf *m, struct tcphdr *th, struct tcpcb *tp, 3400 int tlen, int rstreason) 3401 { 3402 #ifdef INET 3403 struct ip *ip; 3404 #endif 3405 #ifdef INET6 3406 struct ip6_hdr *ip6; 3407 #endif 3408 3409 if (tp != NULL) { 3410 INP_LOCK_ASSERT(tp->t_inpcb); 3411 } 3412 3413 /* Don't bother if destination was broadcast/multicast. */ 3414 if ((tcp_get_flags(th) & TH_RST) || m->m_flags & (M_BCAST|M_MCAST)) 3415 goto drop; 3416 #ifdef INET6 3417 if (mtod(m, struct ip *)->ip_v == 6) { 3418 ip6 = mtod(m, struct ip6_hdr *); 3419 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 3420 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) 3421 goto drop; 3422 /* IPv6 anycast check is done at tcp6_input() */ 3423 } 3424 #endif 3425 #if defined(INET) && defined(INET6) 3426 else 3427 #endif 3428 #ifdef INET 3429 { 3430 ip = mtod(m, struct ip *); 3431 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || 3432 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 3433 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || 3434 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 3435 goto drop; 3436 } 3437 #endif 3438 3439 /* Perform bandwidth limiting. */ 3440 if (badport_bandlim(rstreason) < 0) 3441 goto drop; 3442 3443 /* tcp_respond consumes the mbuf chain. */ 3444 if (tcp_get_flags(th) & TH_ACK) { 3445 tcp_respond(tp, mtod(m, void *), th, m, (tcp_seq)0, 3446 th->th_ack, TH_RST); 3447 } else { 3448 if (tcp_get_flags(th) & TH_SYN) 3449 tlen++; 3450 if (tcp_get_flags(th) & TH_FIN) 3451 tlen++; 3452 tcp_respond(tp, mtod(m, void *), th, m, th->th_seq+tlen, 3453 (tcp_seq)0, TH_RST|TH_ACK); 3454 } 3455 return; 3456 drop: 3457 m_freem(m); 3458 } 3459 3460 /* 3461 * Parse TCP options and place in tcpopt. 3462 */ 3463 void 3464 tcp_dooptions(struct tcpopt *to, u_char *cp, int cnt, int flags) 3465 { 3466 int opt, optlen; 3467 3468 to->to_flags = 0; 3469 for (; cnt > 0; cnt -= optlen, cp += optlen) { 3470 opt = cp[0]; 3471 if (opt == TCPOPT_EOL) 3472 break; 3473 if (opt == TCPOPT_NOP) 3474 optlen = 1; 3475 else { 3476 if (cnt < 2) 3477 break; 3478 optlen = cp[1]; 3479 if (optlen < 2 || optlen > cnt) 3480 break; 3481 } 3482 switch (opt) { 3483 case TCPOPT_MAXSEG: 3484 if (optlen != TCPOLEN_MAXSEG) 3485 continue; 3486 if (!(flags & TO_SYN)) 3487 continue; 3488 to->to_flags |= TOF_MSS; 3489 bcopy((char *)cp + 2, 3490 (char *)&to->to_mss, sizeof(to->to_mss)); 3491 to->to_mss = ntohs(to->to_mss); 3492 break; 3493 case TCPOPT_WINDOW: 3494 if (optlen != TCPOLEN_WINDOW) 3495 continue; 3496 if (!(flags & TO_SYN)) 3497 continue; 3498 to->to_flags |= TOF_SCALE; 3499 to->to_wscale = min(cp[2], TCP_MAX_WINSHIFT); 3500 break; 3501 case TCPOPT_TIMESTAMP: 3502 if (optlen != TCPOLEN_TIMESTAMP) 3503 continue; 3504 to->to_flags |= TOF_TS; 3505 bcopy((char *)cp + 2, 3506 (char *)&to->to_tsval, sizeof(to->to_tsval)); 3507 to->to_tsval = ntohl(to->to_tsval); 3508 bcopy((char *)cp + 6, 3509 (char *)&to->to_tsecr, sizeof(to->to_tsecr)); 3510 to->to_tsecr = ntohl(to->to_tsecr); 3511 break; 3512 case TCPOPT_SIGNATURE: 3513 /* 3514 * In order to reply to a host which has set the 3515 * TCP_SIGNATURE option in its initial SYN, we have 3516 * to record the fact that the option was observed 3517 * here for the syncache code to perform the correct 3518 * response. 3519 */ 3520 if (optlen != TCPOLEN_SIGNATURE) 3521 continue; 3522 to->to_flags |= TOF_SIGNATURE; 3523 to->to_signature = cp + 2; 3524 break; 3525 case TCPOPT_SACK_PERMITTED: 3526 if (optlen != TCPOLEN_SACK_PERMITTED) 3527 continue; 3528 if (!(flags & TO_SYN)) 3529 continue; 3530 if (!V_tcp_do_sack) 3531 continue; 3532 to->to_flags |= TOF_SACKPERM; 3533 break; 3534 case TCPOPT_SACK: 3535 if (optlen <= 2 || (optlen - 2) % TCPOLEN_SACK != 0) 3536 continue; 3537 if (flags & TO_SYN) 3538 continue; 3539 to->to_flags |= TOF_SACK; 3540 to->to_nsacks = (optlen - 2) / TCPOLEN_SACK; 3541 to->to_sacks = cp + 2; 3542 TCPSTAT_INC(tcps_sack_rcv_blocks); 3543 break; 3544 case TCPOPT_FAST_OPEN: 3545 /* 3546 * Cookie length validation is performed by the 3547 * server side cookie checking code or the client 3548 * side cookie cache update code. 3549 */ 3550 if (!(flags & TO_SYN)) 3551 continue; 3552 if (!V_tcp_fastopen_client_enable && 3553 !V_tcp_fastopen_server_enable) 3554 continue; 3555 to->to_flags |= TOF_FASTOPEN; 3556 to->to_tfo_len = optlen - 2; 3557 to->to_tfo_cookie = to->to_tfo_len ? cp + 2 : NULL; 3558 break; 3559 default: 3560 continue; 3561 } 3562 } 3563 } 3564 3565 /* 3566 * Pull out of band byte out of a segment so 3567 * it doesn't appear in the user's data queue. 3568 * It is still reflected in the segment length for 3569 * sequencing purposes. 3570 */ 3571 void 3572 tcp_pulloutofband(struct socket *so, struct tcphdr *th, struct mbuf *m, 3573 int off) 3574 { 3575 int cnt = off + th->th_urp - 1; 3576 3577 while (cnt >= 0) { 3578 if (m->m_len > cnt) { 3579 char *cp = mtod(m, caddr_t) + cnt; 3580 struct tcpcb *tp = sototcpcb(so); 3581 3582 INP_WLOCK_ASSERT(tp->t_inpcb); 3583 3584 tp->t_iobc = *cp; 3585 tp->t_oobflags |= TCPOOB_HAVEDATA; 3586 bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); 3587 m->m_len--; 3588 if (m->m_flags & M_PKTHDR) 3589 m->m_pkthdr.len--; 3590 return; 3591 } 3592 cnt -= m->m_len; 3593 m = m->m_next; 3594 if (m == NULL) 3595 break; 3596 } 3597 panic("tcp_pulloutofband"); 3598 } 3599 3600 /* 3601 * Collect new round-trip time estimate 3602 * and update averages and current timeout. 3603 */ 3604 void 3605 tcp_xmit_timer(struct tcpcb *tp, int rtt) 3606 { 3607 int delta; 3608 3609 INP_WLOCK_ASSERT(tp->t_inpcb); 3610 3611 TCPSTAT_INC(tcps_rttupdated); 3612 tp->t_rttupdated++; 3613 #ifdef STATS 3614 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_RTT, 3615 imax(0, rtt * 1000 / hz)); 3616 #endif 3617 if ((tp->t_srtt != 0) && (tp->t_rxtshift <= TCP_RTT_INVALIDATE)) { 3618 /* 3619 * srtt is stored as fixed point with 5 bits after the 3620 * binary point (i.e., scaled by 8). The following magic 3621 * is equivalent to the smoothing algorithm in rfc793 with 3622 * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed 3623 * point). Adjust rtt to origin 0. 3624 */ 3625 delta = ((rtt - 1) << TCP_DELTA_SHIFT) 3626 - (tp->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT)); 3627 3628 if ((tp->t_srtt += delta) <= 0) 3629 tp->t_srtt = 1; 3630 3631 /* 3632 * We accumulate a smoothed rtt variance (actually, a 3633 * smoothed mean difference), then set the retransmit 3634 * timer to smoothed rtt + 4 times the smoothed variance. 3635 * rttvar is stored as fixed point with 4 bits after the 3636 * binary point (scaled by 16). The following is 3637 * equivalent to rfc793 smoothing with an alpha of .75 3638 * (rttvar = rttvar*3/4 + |delta| / 4). This replaces 3639 * rfc793's wired-in beta. 3640 */ 3641 if (delta < 0) 3642 delta = -delta; 3643 delta -= tp->t_rttvar >> (TCP_RTTVAR_SHIFT - TCP_DELTA_SHIFT); 3644 if ((tp->t_rttvar += delta) <= 0) 3645 tp->t_rttvar = 1; 3646 if (tp->t_rttbest > tp->t_srtt + tp->t_rttvar) 3647 tp->t_rttbest = tp->t_srtt + tp->t_rttvar; 3648 } else { 3649 /* 3650 * No rtt measurement yet - use the unsmoothed rtt. 3651 * Set the variance to half the rtt (so our first 3652 * retransmit happens at 3*rtt). 3653 */ 3654 tp->t_srtt = rtt << TCP_RTT_SHIFT; 3655 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1); 3656 tp->t_rttbest = tp->t_srtt + tp->t_rttvar; 3657 } 3658 tp->t_rtttime = 0; 3659 tp->t_rxtshift = 0; 3660 3661 /* 3662 * the retransmit should happen at rtt + 4 * rttvar. 3663 * Because of the way we do the smoothing, srtt and rttvar 3664 * will each average +1/2 tick of bias. When we compute 3665 * the retransmit timer, we want 1/2 tick of rounding and 3666 * 1 extra tick because of +-1/2 tick uncertainty in the 3667 * firing of the timer. The bias will give us exactly the 3668 * 1.5 tick we need. But, because the bias is 3669 * statistical, we have to test that we don't drop below 3670 * the minimum feasible timer (which is 2 ticks). 3671 */ 3672 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), 3673 max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX); 3674 3675 /* 3676 * We received an ack for a packet that wasn't retransmitted; 3677 * it is probably safe to discard any error indications we've 3678 * received recently. This isn't quite right, but close enough 3679 * for now (a route might have failed after we sent a segment, 3680 * and the return path might not be symmetrical). 3681 */ 3682 tp->t_softerror = 0; 3683 } 3684 3685 /* 3686 * Determine a reasonable value for maxseg size. 3687 * If the route is known, check route for mtu. 3688 * If none, use an mss that can be handled on the outgoing interface 3689 * without forcing IP to fragment. If no route is found, route has no mtu, 3690 * or the destination isn't local, use a default, hopefully conservative 3691 * size (usually 512 or the default IP max size, but no more than the mtu 3692 * of the interface), as we can't discover anything about intervening 3693 * gateways or networks. We also initialize the congestion/slow start 3694 * window to be a single segment if the destination isn't local. 3695 * While looking at the routing entry, we also initialize other path-dependent 3696 * parameters from pre-set or cached values in the routing entry. 3697 * 3698 * NOTE that resulting t_maxseg doesn't include space for TCP options or 3699 * IP options, e.g. IPSEC data, since length of this data may vary, and 3700 * thus it is calculated for every segment separately in tcp_output(). 3701 * 3702 * NOTE that this routine is only called when we process an incoming 3703 * segment, or an ICMP need fragmentation datagram. Outgoing SYN/ACK MSS 3704 * settings are handled in tcp_mssopt(). 3705 */ 3706 void 3707 tcp_mss_update(struct tcpcb *tp, int offer, int mtuoffer, 3708 struct hc_metrics_lite *metricptr, struct tcp_ifcap *cap) 3709 { 3710 int mss = 0; 3711 uint32_t maxmtu = 0; 3712 struct inpcb *inp = tp->t_inpcb; 3713 struct hc_metrics_lite metrics; 3714 #ifdef INET6 3715 int isipv6 = ((inp->inp_vflag & INP_IPV6) != 0) ? 1 : 0; 3716 size_t min_protoh = isipv6 ? 3717 sizeof (struct ip6_hdr) + sizeof (struct tcphdr) : 3718 sizeof (struct tcpiphdr); 3719 #else 3720 size_t min_protoh = sizeof(struct tcpiphdr); 3721 #endif 3722 3723 INP_WLOCK_ASSERT(tp->t_inpcb); 3724 3725 if (tp->t_port) 3726 min_protoh += V_tcp_udp_tunneling_overhead; 3727 if (mtuoffer != -1) { 3728 KASSERT(offer == -1, ("%s: conflict", __func__)); 3729 offer = mtuoffer - min_protoh; 3730 } 3731 3732 /* Initialize. */ 3733 #ifdef INET6 3734 if (isipv6) { 3735 maxmtu = tcp_maxmtu6(&inp->inp_inc, cap); 3736 tp->t_maxseg = V_tcp_v6mssdflt; 3737 } 3738 #endif 3739 #if defined(INET) && defined(INET6) 3740 else 3741 #endif 3742 #ifdef INET 3743 { 3744 maxmtu = tcp_maxmtu(&inp->inp_inc, cap); 3745 tp->t_maxseg = V_tcp_mssdflt; 3746 } 3747 #endif 3748 3749 /* 3750 * No route to sender, stay with default mss and return. 3751 */ 3752 if (maxmtu == 0) { 3753 /* 3754 * In case we return early we need to initialize metrics 3755 * to a defined state as tcp_hc_get() would do for us 3756 * if there was no cache hit. 3757 */ 3758 if (metricptr != NULL) 3759 bzero(metricptr, sizeof(struct hc_metrics_lite)); 3760 return; 3761 } 3762 3763 /* What have we got? */ 3764 switch (offer) { 3765 case 0: 3766 /* 3767 * Offer == 0 means that there was no MSS on the SYN 3768 * segment, in this case we use tcp_mssdflt as 3769 * already assigned to t_maxseg above. 3770 */ 3771 offer = tp->t_maxseg; 3772 break; 3773 3774 case -1: 3775 /* 3776 * Offer == -1 means that we didn't receive SYN yet. 3777 */ 3778 /* FALLTHROUGH */ 3779 3780 default: 3781 /* 3782 * Prevent DoS attack with too small MSS. Round up 3783 * to at least minmss. 3784 */ 3785 offer = max(offer, V_tcp_minmss); 3786 } 3787 3788 /* 3789 * rmx information is now retrieved from tcp_hostcache. 3790 */ 3791 tcp_hc_get(&inp->inp_inc, &metrics); 3792 if (metricptr != NULL) 3793 bcopy(&metrics, metricptr, sizeof(struct hc_metrics_lite)); 3794 3795 /* 3796 * If there's a discovered mtu in tcp hostcache, use it. 3797 * Else, use the link mtu. 3798 */ 3799 if (metrics.rmx_mtu) 3800 mss = min(metrics.rmx_mtu, maxmtu) - min_protoh; 3801 else { 3802 #ifdef INET6 3803 if (isipv6) { 3804 mss = maxmtu - min_protoh; 3805 if (!V_path_mtu_discovery && 3806 !in6_localaddr(&inp->in6p_faddr)) 3807 mss = min(mss, V_tcp_v6mssdflt); 3808 } 3809 #endif 3810 #if defined(INET) && defined(INET6) 3811 else 3812 #endif 3813 #ifdef INET 3814 { 3815 mss = maxmtu - min_protoh; 3816 if (!V_path_mtu_discovery && 3817 !in_localaddr(inp->inp_faddr)) 3818 mss = min(mss, V_tcp_mssdflt); 3819 } 3820 #endif 3821 /* 3822 * XXX - The above conditional (mss = maxmtu - min_protoh) 3823 * probably violates the TCP spec. 3824 * The problem is that, since we don't know the 3825 * other end's MSS, we are supposed to use a conservative 3826 * default. But, if we do that, then MTU discovery will 3827 * never actually take place, because the conservative 3828 * default is much less than the MTUs typically seen 3829 * on the Internet today. For the moment, we'll sweep 3830 * this under the carpet. 3831 * 3832 * The conservative default might not actually be a problem 3833 * if the only case this occurs is when sending an initial 3834 * SYN with options and data to a host we've never talked 3835 * to before. Then, they will reply with an MSS value which 3836 * will get recorded and the new parameters should get 3837 * recomputed. For Further Study. 3838 */ 3839 } 3840 mss = min(mss, offer); 3841 3842 /* 3843 * Sanity check: make sure that maxseg will be large 3844 * enough to allow some data on segments even if the 3845 * all the option space is used (40bytes). Otherwise 3846 * funny things may happen in tcp_output. 3847 * 3848 * XXXGL: shouldn't we reserve space for IP/IPv6 options? 3849 */ 3850 mss = max(mss, 64); 3851 3852 tp->t_maxseg = mss; 3853 } 3854 3855 void 3856 tcp_mss(struct tcpcb *tp, int offer) 3857 { 3858 int mss; 3859 uint32_t bufsize; 3860 struct inpcb *inp; 3861 struct socket *so; 3862 struct hc_metrics_lite metrics; 3863 struct tcp_ifcap cap; 3864 3865 KASSERT(tp != NULL, ("%s: tp == NULL", __func__)); 3866 3867 bzero(&cap, sizeof(cap)); 3868 tcp_mss_update(tp, offer, -1, &metrics, &cap); 3869 3870 mss = tp->t_maxseg; 3871 inp = tp->t_inpcb; 3872 3873 /* 3874 * If there's a pipesize, change the socket buffer to that size, 3875 * don't change if sb_hiwat is different than default (then it 3876 * has been changed on purpose with setsockopt). 3877 * Make the socket buffers an integral number of mss units; 3878 * if the mss is larger than the socket buffer, decrease the mss. 3879 */ 3880 so = inp->inp_socket; 3881 SOCKBUF_LOCK(&so->so_snd); 3882 if ((so->so_snd.sb_hiwat == V_tcp_sendspace) && metrics.rmx_sendpipe) 3883 bufsize = metrics.rmx_sendpipe; 3884 else 3885 bufsize = so->so_snd.sb_hiwat; 3886 if (bufsize < mss) 3887 mss = bufsize; 3888 else { 3889 bufsize = roundup(bufsize, mss); 3890 if (bufsize > sb_max) 3891 bufsize = sb_max; 3892 if (bufsize > so->so_snd.sb_hiwat) 3893 (void)sbreserve_locked(so, SO_SND, bufsize, NULL); 3894 } 3895 SOCKBUF_UNLOCK(&so->so_snd); 3896 /* 3897 * Sanity check: make sure that maxseg will be large 3898 * enough to allow some data on segments even if the 3899 * all the option space is used (40bytes). Otherwise 3900 * funny things may happen in tcp_output. 3901 * 3902 * XXXGL: shouldn't we reserve space for IP/IPv6 options? 3903 */ 3904 tp->t_maxseg = max(mss, 64); 3905 3906 SOCKBUF_LOCK(&so->so_rcv); 3907 if ((so->so_rcv.sb_hiwat == V_tcp_recvspace) && metrics.rmx_recvpipe) 3908 bufsize = metrics.rmx_recvpipe; 3909 else 3910 bufsize = so->so_rcv.sb_hiwat; 3911 if (bufsize > mss) { 3912 bufsize = roundup(bufsize, mss); 3913 if (bufsize > sb_max) 3914 bufsize = sb_max; 3915 if (bufsize > so->so_rcv.sb_hiwat) 3916 (void)sbreserve_locked(so, SO_RCV, bufsize, NULL); 3917 } 3918 SOCKBUF_UNLOCK(&so->so_rcv); 3919 3920 /* Check the interface for TSO capabilities. */ 3921 if (cap.ifcap & CSUM_TSO) { 3922 tp->t_flags |= TF_TSO; 3923 tp->t_tsomax = cap.tsomax; 3924 tp->t_tsomaxsegcount = cap.tsomaxsegcount; 3925 tp->t_tsomaxsegsize = cap.tsomaxsegsize; 3926 } 3927 } 3928 3929 /* 3930 * Determine the MSS option to send on an outgoing SYN. 3931 */ 3932 int 3933 tcp_mssopt(struct in_conninfo *inc) 3934 { 3935 int mss = 0; 3936 uint32_t thcmtu = 0; 3937 uint32_t maxmtu = 0; 3938 size_t min_protoh; 3939 3940 KASSERT(inc != NULL, ("tcp_mssopt with NULL in_conninfo pointer")); 3941 3942 #ifdef INET6 3943 if (inc->inc_flags & INC_ISIPV6) { 3944 mss = V_tcp_v6mssdflt; 3945 maxmtu = tcp_maxmtu6(inc, NULL); 3946 min_protoh = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 3947 } 3948 #endif 3949 #if defined(INET) && defined(INET6) 3950 else 3951 #endif 3952 #ifdef INET 3953 { 3954 mss = V_tcp_mssdflt; 3955 maxmtu = tcp_maxmtu(inc, NULL); 3956 min_protoh = sizeof(struct tcpiphdr); 3957 } 3958 #endif 3959 #if defined(INET6) || defined(INET) 3960 thcmtu = tcp_hc_getmtu(inc); /* IPv4 and IPv6 */ 3961 #endif 3962 3963 if (maxmtu && thcmtu) 3964 mss = min(maxmtu, thcmtu) - min_protoh; 3965 else if (maxmtu || thcmtu) 3966 mss = max(maxmtu, thcmtu) - min_protoh; 3967 3968 return (mss); 3969 } 3970 3971 void 3972 tcp_do_prr_ack(struct tcpcb *tp, struct tcphdr *th, struct tcpopt *to) 3973 { 3974 int snd_cnt = 0, limit = 0, del_data = 0, pipe = 0; 3975 int maxseg = tcp_maxseg(tp); 3976 3977 INP_WLOCK_ASSERT(tp->t_inpcb); 3978 3979 /* 3980 * Compute the amount of data that this ACK is indicating 3981 * (del_data) and an estimate of how many bytes are in the 3982 * network. 3983 */ 3984 if (tcp_is_sack_recovery(tp, to) || 3985 (IN_CONGRECOVERY(tp->t_flags) && 3986 !IN_FASTRECOVERY(tp->t_flags))) { 3987 del_data = tp->sackhint.delivered_data; 3988 if (V_tcp_do_newsack) 3989 pipe = tcp_compute_pipe(tp); 3990 else 3991 pipe = (tp->snd_nxt - tp->snd_fack) + 3992 tp->sackhint.sack_bytes_rexmit; 3993 } else { 3994 if (tp->sackhint.prr_delivered < (tcprexmtthresh * maxseg + 3995 tp->snd_recover - tp->snd_una)) 3996 del_data = maxseg; 3997 pipe = imax(0, tp->snd_max - tp->snd_una - 3998 imin(INT_MAX / 65536, tp->t_dupacks) * maxseg); 3999 } 4000 tp->sackhint.prr_delivered += del_data; 4001 /* 4002 * Proportional Rate Reduction 4003 */ 4004 if (pipe >= tp->snd_ssthresh) { 4005 if (tp->sackhint.recover_fs == 0) 4006 tp->sackhint.recover_fs = 4007 imax(1, tp->snd_nxt - tp->snd_una); 4008 snd_cnt = howmany((long)tp->sackhint.prr_delivered * 4009 tp->snd_ssthresh, tp->sackhint.recover_fs) - 4010 tp->sackhint.prr_out; 4011 } else { 4012 if (V_tcp_do_prr_conservative || (del_data == 0)) 4013 limit = tp->sackhint.prr_delivered - 4014 tp->sackhint.prr_out; 4015 else 4016 limit = imax(tp->sackhint.prr_delivered - 4017 tp->sackhint.prr_out, del_data) + 4018 maxseg; 4019 snd_cnt = imin((tp->snd_ssthresh - pipe), limit); 4020 } 4021 snd_cnt = imax(snd_cnt, 0) / maxseg; 4022 /* 4023 * Send snd_cnt new data into the network in response to this ack. 4024 * If there is going to be a SACK retransmission, adjust snd_cwnd 4025 * accordingly. 4026 */ 4027 if (IN_FASTRECOVERY(tp->t_flags)) { 4028 if (tcp_is_sack_recovery(tp, to)) { 4029 tp->snd_cwnd = tp->snd_nxt - tp->snd_recover + 4030 tp->sackhint.sack_bytes_rexmit + 4031 (snd_cnt * maxseg); 4032 } else { 4033 tp->snd_cwnd = (tp->snd_max - tp->snd_una) + 4034 (snd_cnt * maxseg); 4035 } 4036 } else if (IN_CONGRECOVERY(tp->t_flags)) 4037 tp->snd_cwnd = pipe - del_data + (snd_cnt * maxseg); 4038 tp->snd_cwnd = imax(maxseg, tp->snd_cwnd); 4039 } 4040 4041 /* 4042 * On a partial ack arrives, force the retransmission of the 4043 * next unacknowledged segment. Do not clear tp->t_dupacks. 4044 * By setting snd_nxt to ti_ack, this forces retransmission timer to 4045 * be started again. 4046 */ 4047 void 4048 tcp_newreno_partial_ack(struct tcpcb *tp, struct tcphdr *th) 4049 { 4050 tcp_seq onxt = tp->snd_nxt; 4051 uint32_t ocwnd = tp->snd_cwnd; 4052 u_int maxseg = tcp_maxseg(tp); 4053 4054 INP_WLOCK_ASSERT(tp->t_inpcb); 4055 4056 tcp_timer_activate(tp, TT_REXMT, 0); 4057 tp->t_rtttime = 0; 4058 tp->snd_nxt = th->th_ack; 4059 /* 4060 * Set snd_cwnd to one segment beyond acknowledged offset. 4061 * (tp->snd_una has not yet been updated when this function is called.) 4062 */ 4063 tp->snd_cwnd = maxseg + BYTES_THIS_ACK(tp, th); 4064 tp->t_flags |= TF_ACKNOW; 4065 (void) tcp_output(tp); 4066 tp->snd_cwnd = ocwnd; 4067 if (SEQ_GT(onxt, tp->snd_nxt)) 4068 tp->snd_nxt = onxt; 4069 /* 4070 * Partial window deflation. Relies on fact that tp->snd_una 4071 * not updated yet. 4072 */ 4073 if (tp->snd_cwnd > BYTES_THIS_ACK(tp, th)) 4074 tp->snd_cwnd -= BYTES_THIS_ACK(tp, th); 4075 else 4076 tp->snd_cwnd = 0; 4077 tp->snd_cwnd += maxseg; 4078 } 4079 4080 int 4081 tcp_compute_pipe(struct tcpcb *tp) 4082 { 4083 if (tp->t_fb->tfb_compute_pipe == NULL) { 4084 return (tp->snd_max - tp->snd_una + 4085 tp->sackhint.sack_bytes_rexmit - 4086 tp->sackhint.sacked_bytes); 4087 } else { 4088 return((*tp->t_fb->tfb_compute_pipe)(tp)); 4089 } 4090 } 4091 4092 uint32_t 4093 tcp_compute_initwnd(uint32_t maxseg) 4094 { 4095 /* 4096 * Calculate the Initial Window, also used as Restart Window 4097 * 4098 * RFC5681 Section 3.1 specifies the default conservative values. 4099 * RFC3390 specifies slightly more aggressive values. 4100 * RFC6928 increases it to ten segments. 4101 * Support for user specified value for initial flight size. 4102 */ 4103 if (V_tcp_initcwnd_segments) 4104 return min(V_tcp_initcwnd_segments * maxseg, 4105 max(2 * maxseg, V_tcp_initcwnd_segments * 1460)); 4106 else if (V_tcp_do_rfc3390) 4107 return min(4 * maxseg, max(2 * maxseg, 4380)); 4108 else { 4109 /* Per RFC5681 Section 3.1 */ 4110 if (maxseg > 2190) 4111 return (2 * maxseg); 4112 else if (maxseg > 1095) 4113 return (3 * maxseg); 4114 else 4115 return (4 * maxseg); 4116 } 4117 } 4118