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_rss.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/rss_config.h> 88 #include <net/vnet.h> 89 90 #define TCPSTATES /* for logging */ 91 92 #include <netinet/in.h> 93 #include <netinet/in_kdtrace.h> 94 #include <netinet/in_pcb.h> 95 #include <netinet/in_rss.h> 96 #include <netinet/in_systm.h> 97 #include <netinet/ip.h> 98 #include <netinet/ip_icmp.h> /* required for icmp_var.h */ 99 #include <netinet/icmp_var.h> /* for ICMP_BANDLIM */ 100 #include <netinet/ip_var.h> 101 #include <netinet/ip_options.h> 102 #include <netinet/ip6.h> 103 #include <netinet/icmp6.h> 104 #include <netinet6/in6_pcb.h> 105 #include <netinet6/in6_rss.h> 106 #include <netinet6/in6_var.h> 107 #include <netinet6/ip6_var.h> 108 #include <netinet6/nd6.h> 109 #include <netinet/tcp.h> 110 #include <netinet/tcp_fsm.h> 111 #include <netinet/tcp_seq.h> 112 #include <netinet/tcp_timer.h> 113 #include <netinet/tcp_var.h> 114 #include <netinet/tcp_log_buf.h> 115 #include <netinet6/tcp6_var.h> 116 #include <netinet/tcpip.h> 117 #include <netinet/cc/cc.h> 118 #include <netinet/tcp_fastopen.h> 119 #ifdef TCPPCAP 120 #include <netinet/tcp_pcap.h> 121 #endif 122 #include <netinet/tcp_syncache.h> 123 #ifdef TCP_OFFLOAD 124 #include <netinet/tcp_offload.h> 125 #endif 126 #include <netinet/tcp_ecn.h> 127 #include <netinet/udp.h> 128 129 #include <netipsec/ipsec_support.h> 130 131 #include <machine/in_cksum.h> 132 133 #include <security/mac/mac_framework.h> 134 135 const int tcprexmtthresh = 3; 136 137 VNET_DEFINE(int, tcp_log_in_vain) = 0; 138 SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_in_vain, CTLFLAG_VNET | CTLFLAG_RW, 139 &VNET_NAME(tcp_log_in_vain), 0, 140 "Log all incoming TCP segments to closed ports"); 141 142 VNET_DEFINE(int, blackhole) = 0; 143 #define V_blackhole VNET(blackhole) 144 SYSCTL_INT(_net_inet_tcp, OID_AUTO, blackhole, CTLFLAG_VNET | CTLFLAG_RW, 145 &VNET_NAME(blackhole), 0, 146 "Do not send RST on segments to closed ports"); 147 148 VNET_DEFINE(bool, blackhole_local) = false; 149 #define V_blackhole_local VNET(blackhole_local) 150 SYSCTL_BOOL(_net_inet_tcp, OID_AUTO, blackhole_local, CTLFLAG_VNET | 151 CTLFLAG_RW, &VNET_NAME(blackhole_local), false, 152 "Enforce net.inet.tcp.blackhole for locally originated packets"); 153 154 VNET_DEFINE(int, tcp_delack_enabled) = 1; 155 SYSCTL_INT(_net_inet_tcp, OID_AUTO, delayed_ack, CTLFLAG_VNET | CTLFLAG_RW, 156 &VNET_NAME(tcp_delack_enabled), 0, 157 "Delay ACK to try and piggyback it onto a data packet"); 158 159 VNET_DEFINE(int, drop_synfin) = 0; 160 SYSCTL_INT(_net_inet_tcp, OID_AUTO, drop_synfin, CTLFLAG_VNET | CTLFLAG_RW, 161 &VNET_NAME(drop_synfin), 0, 162 "Drop TCP packets with SYN+FIN set"); 163 164 VNET_DEFINE(int, tcp_do_prr_conservative) = 0; 165 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_prr_conservative, CTLFLAG_VNET | CTLFLAG_RW, 166 &VNET_NAME(tcp_do_prr_conservative), 0, 167 "Do conservative Proportional Rate Reduction"); 168 169 VNET_DEFINE(int, tcp_do_prr) = 1; 170 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_prr, CTLFLAG_VNET | CTLFLAG_RW, 171 &VNET_NAME(tcp_do_prr), 1, 172 "Enable Proportional Rate Reduction per RFC 6937"); 173 174 VNET_DEFINE(int, tcp_do_lrd) = 0; 175 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_lrd, CTLFLAG_VNET | CTLFLAG_RW, 176 &VNET_NAME(tcp_do_lrd), 1, 177 "Perform Lost Retransmission Detection"); 178 179 VNET_DEFINE(int, tcp_do_newcwv) = 0; 180 SYSCTL_INT(_net_inet_tcp, OID_AUTO, newcwv, CTLFLAG_VNET | CTLFLAG_RW, 181 &VNET_NAME(tcp_do_newcwv), 0, 182 "Enable New Congestion Window Validation per RFC7661"); 183 184 VNET_DEFINE(int, tcp_do_rfc3042) = 1; 185 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3042, CTLFLAG_VNET | CTLFLAG_RW, 186 &VNET_NAME(tcp_do_rfc3042), 0, 187 "Enable RFC 3042 (Limited Transmit)"); 188 189 VNET_DEFINE(int, tcp_do_rfc3390) = 1; 190 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3390, CTLFLAG_VNET | CTLFLAG_RW, 191 &VNET_NAME(tcp_do_rfc3390), 0, 192 "Enable RFC 3390 (Increasing TCP's Initial Congestion Window)"); 193 194 VNET_DEFINE(int, tcp_initcwnd_segments) = 10; 195 SYSCTL_INT(_net_inet_tcp, OID_AUTO, initcwnd_segments, 196 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(tcp_initcwnd_segments), 0, 197 "Slow-start flight size (initial congestion window) in number of segments"); 198 199 VNET_DEFINE(int, tcp_do_rfc3465) = 1; 200 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3465, CTLFLAG_VNET | CTLFLAG_RW, 201 &VNET_NAME(tcp_do_rfc3465), 0, 202 "Enable RFC 3465 (Appropriate Byte Counting)"); 203 204 VNET_DEFINE(int, tcp_abc_l_var) = 2; 205 SYSCTL_INT(_net_inet_tcp, OID_AUTO, abc_l_var, CTLFLAG_VNET | CTLFLAG_RW, 206 &VNET_NAME(tcp_abc_l_var), 2, 207 "Cap the max cwnd increment during slow-start to this number of segments"); 208 209 VNET_DEFINE(int, tcp_insecure_syn) = 0; 210 SYSCTL_INT(_net_inet_tcp, OID_AUTO, insecure_syn, CTLFLAG_VNET | CTLFLAG_RW, 211 &VNET_NAME(tcp_insecure_syn), 0, 212 "Follow RFC793 instead of RFC5961 criteria for accepting SYN packets"); 213 214 VNET_DEFINE(int, tcp_insecure_rst) = 0; 215 SYSCTL_INT(_net_inet_tcp, OID_AUTO, insecure_rst, CTLFLAG_VNET | CTLFLAG_RW, 216 &VNET_NAME(tcp_insecure_rst), 0, 217 "Follow RFC793 instead of RFC5961 criteria for accepting RST packets"); 218 219 VNET_DEFINE(int, tcp_recvspace) = 1024*64; 220 #define V_tcp_recvspace VNET(tcp_recvspace) 221 SYSCTL_INT(_net_inet_tcp, TCPCTL_RECVSPACE, recvspace, CTLFLAG_VNET | CTLFLAG_RW, 222 &VNET_NAME(tcp_recvspace), 0, "Initial receive socket buffer size"); 223 224 VNET_DEFINE(int, tcp_do_autorcvbuf) = 1; 225 SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_auto, CTLFLAG_VNET | CTLFLAG_RW, 226 &VNET_NAME(tcp_do_autorcvbuf), 0, 227 "Enable automatic receive buffer sizing"); 228 229 VNET_DEFINE(int, tcp_autorcvbuf_max) = 2*1024*1024; 230 SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_max, CTLFLAG_VNET | CTLFLAG_RW, 231 &VNET_NAME(tcp_autorcvbuf_max), 0, 232 "Max size of automatic receive buffer"); 233 234 VNET_DEFINE(struct inpcbinfo, tcbinfo); 235 236 /* 237 * TCP statistics are stored in an array of counter(9)s, which size matches 238 * size of struct tcpstat. TCP running connection count is a regular array. 239 */ 240 VNET_PCPUSTAT_DEFINE(struct tcpstat, tcpstat); 241 SYSCTL_VNET_PCPUSTAT(_net_inet_tcp, TCPCTL_STATS, stats, struct tcpstat, 242 tcpstat, "TCP statistics (struct tcpstat, netinet/tcp_var.h)"); 243 VNET_DEFINE(counter_u64_t, tcps_states[TCP_NSTATES]); 244 SYSCTL_COUNTER_U64_ARRAY(_net_inet_tcp, TCPCTL_STATES, states, CTLFLAG_RD | 245 CTLFLAG_VNET, &VNET_NAME(tcps_states)[0], TCP_NSTATES, 246 "TCP connection counts by TCP state"); 247 248 /* 249 * Kernel module interface for updating tcpstat. The first argument is an index 250 * into tcpstat treated as an array. 251 */ 252 void 253 kmod_tcpstat_add(int statnum, int val) 254 { 255 256 counter_u64_add(VNET(tcpstat)[statnum], val); 257 } 258 259 /* 260 * Make sure that we only start a SACK loss recovery when 261 * receiving a duplicate ACK with a SACK block, and also 262 * complete SACK loss recovery in case the other end 263 * reneges. 264 */ 265 static bool inline 266 tcp_is_sack_recovery(struct tcpcb *tp, struct tcpopt *to) 267 { 268 return ((tp->t_flags & TF_SACK_PERMIT) && 269 ((to->to_flags & TOF_SACK) || 270 (!TAILQ_EMPTY(&tp->snd_holes)))); 271 } 272 273 #ifdef TCP_HHOOK 274 /* 275 * Wrapper for the TCP established input helper hook. 276 */ 277 void 278 hhook_run_tcp_est_in(struct tcpcb *tp, struct tcphdr *th, struct tcpopt *to) 279 { 280 struct tcp_hhook_data hhook_data; 281 282 if (V_tcp_hhh[HHOOK_TCP_EST_IN]->hhh_nhooks > 0) { 283 hhook_data.tp = tp; 284 hhook_data.th = th; 285 hhook_data.to = to; 286 287 hhook_run_hooks(V_tcp_hhh[HHOOK_TCP_EST_IN], &hhook_data, 288 &tp->t_osd); 289 } 290 } 291 #endif 292 293 /* 294 * CC wrapper hook functions 295 */ 296 void 297 cc_ack_received(struct tcpcb *tp, struct tcphdr *th, uint16_t nsegs, 298 uint16_t type) 299 { 300 #ifdef STATS 301 int32_t gput; 302 #endif 303 304 INP_WLOCK_ASSERT(tptoinpcb(tp)); 305 306 tp->t_ccv.nsegs = nsegs; 307 tp->t_ccv.bytes_this_ack = BYTES_THIS_ACK(tp, th); 308 if ((!V_tcp_do_newcwv && (tp->snd_cwnd <= tp->snd_wnd)) || 309 (V_tcp_do_newcwv && (tp->snd_cwnd <= tp->snd_wnd) && 310 (tp->snd_cwnd < (tcp_compute_pipe(tp) * 2)))) 311 tp->t_ccv.flags |= CCF_CWND_LIMITED; 312 else 313 tp->t_ccv.flags &= ~CCF_CWND_LIMITED; 314 315 if (type == CC_ACK) { 316 #ifdef STATS 317 stats_voi_update_abs_s32(tp->t_stats, VOI_TCP_CALCFRWINDIFF, 318 ((int32_t)tp->snd_cwnd) - tp->snd_wnd); 319 if (!IN_RECOVERY(tp->t_flags)) 320 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_ACKLEN, 321 tp->t_ccv.bytes_this_ack / (tcp_maxseg(tp) * nsegs)); 322 if ((tp->t_flags & TF_GPUTINPROG) && 323 SEQ_GEQ(th->th_ack, tp->gput_ack)) { 324 /* 325 * Compute goodput in bits per millisecond. 326 */ 327 gput = (((int64_t)SEQ_SUB(th->th_ack, tp->gput_seq)) << 3) / 328 max(1, tcp_ts_getticks() - tp->gput_ts); 329 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_GPUT, 330 gput); 331 /* 332 * XXXLAS: This is a temporary hack, and should be 333 * chained off VOI_TCP_GPUT when stats(9) grows an API 334 * to deal with chained VOIs. 335 */ 336 if (tp->t_stats_gput_prev > 0) 337 stats_voi_update_abs_s32(tp->t_stats, 338 VOI_TCP_GPUT_ND, 339 ((gput - tp->t_stats_gput_prev) * 100) / 340 tp->t_stats_gput_prev); 341 tp->t_flags &= ~TF_GPUTINPROG; 342 tp->t_stats_gput_prev = gput; 343 } 344 #endif /* STATS */ 345 if (tp->snd_cwnd > tp->snd_ssthresh) { 346 tp->t_bytes_acked += tp->t_ccv.bytes_this_ack; 347 if (tp->t_bytes_acked >= tp->snd_cwnd) { 348 tp->t_bytes_acked -= tp->snd_cwnd; 349 tp->t_ccv.flags |= CCF_ABC_SENTAWND; 350 } 351 } else { 352 tp->t_ccv.flags &= ~CCF_ABC_SENTAWND; 353 tp->t_bytes_acked = 0; 354 } 355 } 356 357 if (CC_ALGO(tp)->ack_received != NULL) { 358 /* XXXLAS: Find a way to live without this */ 359 tp->t_ccv.curack = th->th_ack; 360 CC_ALGO(tp)->ack_received(&tp->t_ccv, type); 361 } 362 #ifdef STATS 363 stats_voi_update_abs_ulong(tp->t_stats, VOI_TCP_LCWIN, tp->snd_cwnd); 364 #endif 365 } 366 367 void 368 cc_conn_init(struct tcpcb *tp) 369 { 370 struct hc_metrics_lite metrics; 371 struct inpcb *inp = tptoinpcb(tp); 372 u_int maxseg; 373 int rtt; 374 375 INP_WLOCK_ASSERT(inp); 376 377 tcp_hc_get(&inp->inp_inc, &metrics); 378 maxseg = tcp_maxseg(tp); 379 380 if (tp->t_srtt == 0 && (rtt = metrics.rmx_rtt)) { 381 tp->t_srtt = rtt; 382 TCPSTAT_INC(tcps_usedrtt); 383 if (metrics.rmx_rttvar) { 384 tp->t_rttvar = metrics.rmx_rttvar; 385 TCPSTAT_INC(tcps_usedrttvar); 386 } else { 387 /* default variation is +- 1 rtt */ 388 tp->t_rttvar = 389 tp->t_srtt * TCP_RTTVAR_SCALE / TCP_RTT_SCALE; 390 } 391 TCPT_RANGESET(tp->t_rxtcur, 392 ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1, 393 tp->t_rttmin, TCPTV_REXMTMAX); 394 } 395 if (metrics.rmx_ssthresh) { 396 /* 397 * There's some sort of gateway or interface 398 * buffer limit on the path. Use this to set 399 * the slow start threshold, but set the 400 * threshold to no less than 2*mss. 401 */ 402 tp->snd_ssthresh = max(2 * maxseg, metrics.rmx_ssthresh); 403 TCPSTAT_INC(tcps_usedssthresh); 404 } 405 406 /* 407 * Set the initial slow-start flight size. 408 * 409 * If a SYN or SYN/ACK was lost and retransmitted, we have to 410 * reduce the initial CWND to one segment as congestion is likely 411 * requiring us to be cautious. 412 */ 413 if (tp->snd_cwnd == 1) 414 tp->snd_cwnd = maxseg; /* SYN(-ACK) lost */ 415 else 416 tp->snd_cwnd = tcp_compute_initwnd(maxseg); 417 418 if (CC_ALGO(tp)->conn_init != NULL) 419 CC_ALGO(tp)->conn_init(&tp->t_ccv); 420 } 421 422 void inline 423 cc_cong_signal(struct tcpcb *tp, struct tcphdr *th, uint32_t type) 424 { 425 INP_WLOCK_ASSERT(tptoinpcb(tp)); 426 427 #ifdef STATS 428 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_CSIG, type); 429 #endif 430 431 switch(type) { 432 case CC_NDUPACK: 433 if (!IN_FASTRECOVERY(tp->t_flags)) { 434 tp->snd_recover = tp->snd_max; 435 if (tp->t_flags2 & TF2_ECN_PERMIT) 436 tp->t_flags2 |= TF2_ECN_SND_CWR; 437 } 438 break; 439 case CC_ECN: 440 if (!IN_CONGRECOVERY(tp->t_flags) || 441 /* 442 * Allow ECN reaction on ACK to CWR, if 443 * that data segment was also CE marked. 444 */ 445 SEQ_GEQ(th->th_ack, tp->snd_recover)) { 446 EXIT_CONGRECOVERY(tp->t_flags); 447 TCPSTAT_INC(tcps_ecn_rcwnd); 448 tp->snd_recover = tp->snd_max + 1; 449 if (tp->t_flags2 & TF2_ECN_PERMIT) 450 tp->t_flags2 |= TF2_ECN_SND_CWR; 451 } 452 break; 453 case CC_RTO: 454 tp->t_dupacks = 0; 455 tp->t_bytes_acked = 0; 456 EXIT_RECOVERY(tp->t_flags); 457 if (tp->t_flags2 & TF2_ECN_PERMIT) 458 tp->t_flags2 |= TF2_ECN_SND_CWR; 459 break; 460 case CC_RTO_ERR: 461 TCPSTAT_INC(tcps_sndrexmitbad); 462 /* RTO was unnecessary, so reset everything. */ 463 tp->snd_cwnd = tp->snd_cwnd_prev; 464 tp->snd_ssthresh = tp->snd_ssthresh_prev; 465 tp->snd_recover = tp->snd_recover_prev; 466 if (tp->t_flags & TF_WASFRECOVERY) 467 ENTER_FASTRECOVERY(tp->t_flags); 468 if (tp->t_flags & TF_WASCRECOVERY) 469 ENTER_CONGRECOVERY(tp->t_flags); 470 tp->snd_nxt = tp->snd_max; 471 tp->t_flags &= ~TF_PREVVALID; 472 tp->t_badrxtwin = 0; 473 break; 474 } 475 476 if (CC_ALGO(tp)->cong_signal != NULL) { 477 if (th != NULL) 478 tp->t_ccv.curack = th->th_ack; 479 CC_ALGO(tp)->cong_signal(&tp->t_ccv, type); 480 } 481 } 482 483 void inline 484 cc_post_recovery(struct tcpcb *tp, struct tcphdr *th) 485 { 486 INP_WLOCK_ASSERT(tptoinpcb(tp)); 487 488 /* XXXLAS: KASSERT that we're in recovery? */ 489 490 if (CC_ALGO(tp)->post_recovery != NULL) { 491 tp->t_ccv.curack = th->th_ack; 492 CC_ALGO(tp)->post_recovery(&tp->t_ccv); 493 } 494 /* XXXLAS: EXIT_RECOVERY ? */ 495 tp->t_bytes_acked = 0; 496 tp->sackhint.delivered_data = 0; 497 tp->sackhint.prr_out = 0; 498 } 499 500 /* 501 * Indicate whether this ack should be delayed. We can delay the ack if 502 * following conditions are met: 503 * - There is no delayed ack timer in progress. 504 * - Our last ack wasn't a 0-sized window. We never want to delay 505 * the ack that opens up a 0-sized window. 506 * - LRO wasn't used for this segment. We make sure by checking that the 507 * segment size is not larger than the MSS. 508 */ 509 #define DELAY_ACK(tp, tlen) \ 510 ((!tcp_timer_active(tp, TT_DELACK) && \ 511 (tp->t_flags & TF_RXWIN0SENT) == 0) && \ 512 (tlen <= tp->t_maxseg) && \ 513 (V_tcp_delack_enabled || (tp->t_flags & TF_NEEDSYN))) 514 515 void inline 516 cc_ecnpkt_handler_flags(struct tcpcb *tp, uint16_t flags, uint8_t iptos) 517 { 518 INP_WLOCK_ASSERT(tptoinpcb(tp)); 519 520 if (CC_ALGO(tp)->ecnpkt_handler != NULL) { 521 switch (iptos & IPTOS_ECN_MASK) { 522 case IPTOS_ECN_CE: 523 tp->t_ccv.flags |= CCF_IPHDR_CE; 524 break; 525 case IPTOS_ECN_ECT0: 526 /* FALLTHROUGH */ 527 case IPTOS_ECN_ECT1: 528 /* FALLTHROUGH */ 529 case IPTOS_ECN_NOTECT: 530 tp->t_ccv.flags &= ~CCF_IPHDR_CE; 531 break; 532 } 533 534 if (flags & TH_CWR) 535 tp->t_ccv.flags |= CCF_TCPHDR_CWR; 536 else 537 tp->t_ccv.flags &= ~CCF_TCPHDR_CWR; 538 539 CC_ALGO(tp)->ecnpkt_handler(&tp->t_ccv); 540 541 if (tp->t_ccv.flags & CCF_ACKNOW) { 542 tcp_timer_activate(tp, TT_DELACK, tcp_delacktime); 543 tp->t_flags |= TF_ACKNOW; 544 } 545 } 546 } 547 548 void inline 549 cc_ecnpkt_handler(struct tcpcb *tp, struct tcphdr *th, uint8_t iptos) 550 { 551 cc_ecnpkt_handler_flags(tp, tcp_get_flags(th), iptos); 552 } 553 554 /* 555 * TCP input handling is split into multiple parts: 556 * tcp6_input is a thin wrapper around tcp_input for the extended 557 * ip6_protox[] call format in ip6_input 558 * tcp_input handles primary segment validation, inpcb lookup and 559 * SYN processing on listen sockets 560 * tcp_do_segment processes the ACK and text of the segment for 561 * establishing, established and closing connections 562 */ 563 #ifdef INET6 564 int 565 tcp6_input_with_port(struct mbuf **mp, int *offp, int proto, uint16_t port) 566 { 567 struct mbuf *m; 568 struct in6_ifaddr *ia6; 569 struct ip6_hdr *ip6; 570 571 m = *mp; 572 if (m->m_len < *offp + sizeof(struct tcphdr)) { 573 m = m_pullup(m, *offp + sizeof(struct tcphdr)); 574 if (m == NULL) { 575 *mp = m; 576 TCPSTAT_INC(tcps_rcvshort); 577 return (IPPROTO_DONE); 578 } 579 } 580 581 /* 582 * draft-itojun-ipv6-tcp-to-anycast 583 * better place to put this in? 584 */ 585 ip6 = mtod(m, struct ip6_hdr *); 586 ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */, false); 587 if (ia6 && (ia6->ia6_flags & IN6_IFF_ANYCAST)) { 588 icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR, 589 (caddr_t)&ip6->ip6_dst - (caddr_t)ip6); 590 *mp = NULL; 591 return (IPPROTO_DONE); 592 } 593 594 *mp = m; 595 return (tcp_input_with_port(mp, offp, proto, port)); 596 } 597 598 int 599 tcp6_input(struct mbuf **mp, int *offp, int proto) 600 { 601 602 return(tcp6_input_with_port(mp, offp, proto, 0)); 603 } 604 #endif /* INET6 */ 605 606 int 607 tcp_input_with_port(struct mbuf **mp, int *offp, int proto, uint16_t port) 608 { 609 struct mbuf *m = *mp; 610 struct tcphdr *th = NULL; 611 struct ip *ip = NULL; 612 struct inpcb *inp = NULL; 613 struct tcpcb *tp = NULL; 614 struct socket *so = NULL; 615 u_char *optp = NULL; 616 int off0; 617 int optlen = 0; 618 #ifdef INET 619 int len; 620 uint8_t ipttl; 621 #endif 622 int tlen = 0, off; 623 int drop_hdrlen; 624 int thflags; 625 int rstreason = 0; /* For badport_bandlim accounting purposes */ 626 int lookupflag; 627 uint8_t iptos; 628 struct m_tag *fwd_tag = NULL; 629 #ifdef INET6 630 struct ip6_hdr *ip6 = NULL; 631 int isipv6; 632 #else 633 const void *ip6 = NULL; 634 #endif /* INET6 */ 635 struct tcpopt to; /* options in this segment */ 636 char *s = NULL; /* address and port logging */ 637 638 NET_EPOCH_ASSERT(); 639 640 #ifdef INET6 641 isipv6 = (mtod(m, struct ip *)->ip_v == 6) ? 1 : 0; 642 #endif 643 644 off0 = *offp; 645 m = *mp; 646 *mp = NULL; 647 to.to_flags = 0; 648 TCPSTAT_INC(tcps_rcvtotal); 649 650 #ifdef INET6 651 if (isipv6) { 652 ip6 = mtod(m, struct ip6_hdr *); 653 th = (struct tcphdr *)((caddr_t)ip6 + off0); 654 tlen = sizeof(*ip6) + ntohs(ip6->ip6_plen) - off0; 655 if (port) 656 goto skip6_csum; 657 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID_IPV6) { 658 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 659 th->th_sum = m->m_pkthdr.csum_data; 660 else 661 th->th_sum = in6_cksum_pseudo(ip6, tlen, 662 IPPROTO_TCP, m->m_pkthdr.csum_data); 663 th->th_sum ^= 0xffff; 664 } else 665 th->th_sum = in6_cksum(m, IPPROTO_TCP, off0, tlen); 666 if (th->th_sum) { 667 TCPSTAT_INC(tcps_rcvbadsum); 668 goto drop; 669 } 670 skip6_csum: 671 /* 672 * Be proactive about unspecified IPv6 address in source. 673 * As we use all-zero to indicate unbounded/unconnected pcb, 674 * unspecified IPv6 address can be used to confuse us. 675 * 676 * Note that packets with unspecified IPv6 destination is 677 * already dropped in ip6_input. 678 */ 679 KASSERT(!IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_dst), 680 ("%s: unspecified destination v6 address", __func__)); 681 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 682 IP6STAT_INC(ip6s_badscope); /* XXX */ 683 goto drop; 684 } 685 iptos = IPV6_TRAFFIC_CLASS(ip6); 686 } 687 #endif 688 #if defined(INET) && defined(INET6) 689 else 690 #endif 691 #ifdef INET 692 { 693 /* 694 * Get IP and TCP header together in first mbuf. 695 * Note: IP leaves IP header in first mbuf. 696 */ 697 if (off0 > sizeof (struct ip)) { 698 ip_stripoptions(m); 699 off0 = sizeof(struct ip); 700 } 701 if (m->m_len < sizeof (struct tcpiphdr)) { 702 if ((m = m_pullup(m, sizeof (struct tcpiphdr))) 703 == NULL) { 704 TCPSTAT_INC(tcps_rcvshort); 705 return (IPPROTO_DONE); 706 } 707 } 708 ip = mtod(m, struct ip *); 709 th = (struct tcphdr *)((caddr_t)ip + off0); 710 tlen = ntohs(ip->ip_len) - off0; 711 712 iptos = ip->ip_tos; 713 if (port) 714 goto skip_csum; 715 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) { 716 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 717 th->th_sum = m->m_pkthdr.csum_data; 718 else 719 th->th_sum = in_pseudo(ip->ip_src.s_addr, 720 ip->ip_dst.s_addr, 721 htonl(m->m_pkthdr.csum_data + tlen + 722 IPPROTO_TCP)); 723 th->th_sum ^= 0xffff; 724 } else { 725 struct ipovly *ipov = (struct ipovly *)ip; 726 727 /* 728 * Checksum extended TCP header and data. 729 */ 730 len = off0 + tlen; 731 ipttl = ip->ip_ttl; 732 bzero(ipov->ih_x1, sizeof(ipov->ih_x1)); 733 ipov->ih_len = htons(tlen); 734 th->th_sum = in_cksum(m, len); 735 /* Reset length for SDT probes. */ 736 ip->ip_len = htons(len); 737 /* Reset TOS bits */ 738 ip->ip_tos = iptos; 739 /* Re-initialization for later version check */ 740 ip->ip_ttl = ipttl; 741 ip->ip_v = IPVERSION; 742 ip->ip_hl = off0 >> 2; 743 } 744 skip_csum: 745 if (th->th_sum && (port == 0)) { 746 TCPSTAT_INC(tcps_rcvbadsum); 747 goto drop; 748 } 749 KASSERT(ip->ip_dst.s_addr != INADDR_ANY, 750 ("%s: unspecified destination v4 address", __func__)); 751 if (__predict_false(ip->ip_src.s_addr == INADDR_ANY)) { 752 IPSTAT_INC(ips_badaddr); 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 & ~INPLOOKUP_WILDCARD, 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 & ~INPLOOKUP_WILDCARD, 881 m->m_pkthdr.rcvif, m); 882 if (!inp) { 883 /* 884 * It's new. Try to find the ambushing socket. 885 * Because we've rewritten the destination address, 886 * any hardware-generated hash is ignored. 887 */ 888 inp = in_pcblookup(&V_tcbinfo, ip->ip_src, 889 th->th_sport, next_hop->sin_addr, 890 next_hop->sin_port ? ntohs(next_hop->sin_port) : 891 th->th_dport, lookupflag, m->m_pkthdr.rcvif); 892 } 893 } else 894 inp = in_pcblookup_mbuf(&V_tcbinfo, ip->ip_src, 895 th->th_sport, ip->ip_dst, th->th_dport, lookupflag, 896 m->m_pkthdr.rcvif, m); 897 #endif /* INET */ 898 899 /* 900 * If the INPCB does not exist then all data in the incoming 901 * segment is discarded and an appropriate RST is sent back. 902 * XXX MRT Send RST using which routing table? 903 */ 904 if (inp == NULL) { 905 if (rstreason != 0) { 906 /* We came here after second (safety) lookup. */ 907 MPASS((lookupflag & INPLOOKUP_WILDCARD) == 0); 908 goto dropwithreset; 909 } 910 /* 911 * Log communication attempts to ports that are not 912 * in use. 913 */ 914 if ((V_tcp_log_in_vain == 1 && (thflags & TH_SYN)) || 915 V_tcp_log_in_vain == 2) { 916 if ((s = tcp_log_vain(NULL, th, (void *)ip, ip6))) 917 log(LOG_INFO, "%s; %s: Connection attempt " 918 "to closed port\n", s, __func__); 919 } 920 /* 921 * When blackholing do not respond with a RST but 922 * completely ignore the segment and drop it. 923 */ 924 if (((V_blackhole == 1 && (thflags & TH_SYN)) || 925 V_blackhole == 2) && (V_blackhole_local || ( 926 #ifdef INET6 927 isipv6 ? !in6_localaddr(&ip6->ip6_src) : 928 #endif 929 #ifdef INET 930 !in_localip(ip->ip_src) 931 #else 932 true 933 #endif 934 ))) 935 goto dropunlock; 936 937 rstreason = BANDLIM_RST_CLOSEDPORT; 938 goto dropwithreset; 939 } 940 INP_LOCK_ASSERT(inp); 941 942 if ((inp->inp_flowtype == M_HASHTYPE_NONE) && 943 !SOLISTENING(inp->inp_socket)) { 944 if (M_HASHTYPE_GET(m) != M_HASHTYPE_NONE) { 945 inp->inp_flowid = m->m_pkthdr.flowid; 946 inp->inp_flowtype = M_HASHTYPE_GET(m); 947 #ifdef RSS 948 } else { 949 /* assign flowid by software RSS hash */ 950 #ifdef INET6 951 if (isipv6) { 952 rss_proto_software_hash_v6(&inp->in6p_faddr, 953 &inp->in6p_laddr, 954 inp->inp_fport, 955 inp->inp_lport, 956 IPPROTO_TCP, 957 &inp->inp_flowid, 958 &inp->inp_flowtype); 959 } else 960 #endif /* INET6 */ 961 { 962 rss_proto_software_hash_v4(inp->inp_faddr, 963 inp->inp_laddr, 964 inp->inp_fport, 965 inp->inp_lport, 966 IPPROTO_TCP, 967 &inp->inp_flowid, 968 &inp->inp_flowtype); 969 } 970 #endif /* RSS */ 971 } 972 } 973 #if defined(IPSEC) || defined(IPSEC_SUPPORT) 974 #ifdef INET6 975 if (isipv6 && IPSEC_ENABLED(ipv6) && 976 IPSEC_CHECK_POLICY(ipv6, m, inp) != 0) { 977 goto dropunlock; 978 } 979 #ifdef INET 980 else 981 #endif 982 #endif /* INET6 */ 983 #ifdef INET 984 if (IPSEC_ENABLED(ipv4) && 985 IPSEC_CHECK_POLICY(ipv4, m, inp) != 0) { 986 goto dropunlock; 987 } 988 #endif /* INET */ 989 #endif /* IPSEC */ 990 991 /* 992 * Check the minimum TTL for socket. 993 */ 994 if (inp->inp_ip_minttl != 0) { 995 #ifdef INET6 996 if (isipv6) { 997 if (inp->inp_ip_minttl > ip6->ip6_hlim) 998 goto dropunlock; 999 } else 1000 #endif 1001 if (inp->inp_ip_minttl > ip->ip_ttl) 1002 goto dropunlock; 1003 } 1004 1005 tp = intotcpcb(inp); 1006 switch (tp->t_state) { 1007 case TCPS_TIME_WAIT: 1008 /* 1009 * A previous connection in TIMEWAIT state is supposed to catch 1010 * stray or duplicate segments arriving late. If this segment 1011 * was a legitimate new connection attempt, the old INPCB gets 1012 * removed and we can try again to find a listening socket. 1013 */ 1014 tcp_dooptions(&to, optp, optlen, 1015 (thflags & TH_SYN) ? TO_SYN : 0); 1016 /* 1017 * tcp_twcheck unlocks the inp always, and frees the m if fails. 1018 */ 1019 if (tcp_twcheck(inp, &to, th, m, tlen)) 1020 goto findpcb; 1021 return (IPPROTO_DONE); 1022 case TCPS_CLOSED: 1023 /* 1024 * The TCPCB may no longer exist if the connection is winding 1025 * down or it is in the CLOSED state. Either way we drop the 1026 * segment and send an appropriate response. 1027 */ 1028 rstreason = BANDLIM_RST_CLOSEDPORT; 1029 goto dropwithreset; 1030 } 1031 1032 if ((tp->t_port != port) && (tp->t_state > TCPS_LISTEN)) { 1033 rstreason = BANDLIM_RST_CLOSEDPORT; 1034 goto dropwithreset; 1035 } 1036 1037 #ifdef TCP_OFFLOAD 1038 if (tp->t_flags & TF_TOE) { 1039 tcp_offload_input(tp, m); 1040 m = NULL; /* consumed by the TOE driver */ 1041 goto dropunlock; 1042 } 1043 #endif 1044 1045 #ifdef MAC 1046 if (mac_inpcb_check_deliver(inp, m)) 1047 goto dropunlock; 1048 #endif 1049 so = inp->inp_socket; 1050 KASSERT(so != NULL, ("%s: so == NULL", __func__)); 1051 /* 1052 * When the socket is accepting connections (the INPCB is in LISTEN 1053 * state) we look into the SYN cache if this is a new connection 1054 * attempt or the completion of a previous one. 1055 */ 1056 KASSERT(tp->t_state == TCPS_LISTEN || !SOLISTENING(so), 1057 ("%s: so accepting but tp %p not listening", __func__, tp)); 1058 if (tp->t_state == TCPS_LISTEN && SOLISTENING(so)) { 1059 struct in_conninfo inc; 1060 1061 bzero(&inc, sizeof(inc)); 1062 #ifdef INET6 1063 if (isipv6) { 1064 inc.inc_flags |= INC_ISIPV6; 1065 if (inp->inp_inc.inc_flags & INC_IPV6MINMTU) 1066 inc.inc_flags |= INC_IPV6MINMTU; 1067 inc.inc6_faddr = ip6->ip6_src; 1068 inc.inc6_laddr = ip6->ip6_dst; 1069 } else 1070 #endif 1071 { 1072 inc.inc_faddr = ip->ip_src; 1073 inc.inc_laddr = ip->ip_dst; 1074 } 1075 inc.inc_fport = th->th_sport; 1076 inc.inc_lport = th->th_dport; 1077 inc.inc_fibnum = so->so_fibnum; 1078 1079 /* 1080 * Check for an existing connection attempt in syncache if 1081 * the flag is only ACK. A successful lookup creates a new 1082 * socket appended to the listen queue in SYN_RECEIVED state. 1083 */ 1084 if ((thflags & (TH_RST|TH_ACK|TH_SYN)) == TH_ACK) { 1085 /* 1086 * Parse the TCP options here because 1087 * syncookies need access to the reflected 1088 * timestamp. 1089 */ 1090 tcp_dooptions(&to, optp, optlen, 0); 1091 /* 1092 * NB: syncache_expand() doesn't unlock inp. 1093 */ 1094 rstreason = syncache_expand(&inc, &to, th, &so, m, port); 1095 if (rstreason < 0) { 1096 /* 1097 * A failing TCP MD5 signature comparison 1098 * must result in the segment being dropped 1099 * and must not produce any response back 1100 * to the sender. 1101 */ 1102 goto dropunlock; 1103 } else if (rstreason == 0) { 1104 /* 1105 * No syncache entry, or ACK was not for our 1106 * SYN/ACK. Do our protection against double 1107 * ACK. If peer sent us 2 ACKs, then for the 1108 * first one syncache_expand() successfully 1109 * converted syncache entry into a socket, 1110 * while we were waiting on the inpcb lock. We 1111 * don't want to sent RST for the second ACK, 1112 * so we perform second lookup without wildcard 1113 * match, hoping to find the new socket. If 1114 * the ACK is stray indeed, rstreason would 1115 * hint the above code that the lookup was a 1116 * second attempt. 1117 * 1118 * NB: syncache did its own logging 1119 * of the failure cause. 1120 */ 1121 INP_WUNLOCK(inp); 1122 rstreason = BANDLIM_RST_OPENPORT; 1123 lookupflag &= ~INPLOOKUP_WILDCARD; 1124 goto findpcb; 1125 } 1126 tfo_socket_result: 1127 if (so == NULL) { 1128 /* 1129 * We completed the 3-way handshake 1130 * but could not allocate a socket 1131 * either due to memory shortage, 1132 * listen queue length limits or 1133 * global socket limits. Send RST 1134 * or wait and have the remote end 1135 * retransmit the ACK for another 1136 * try. 1137 */ 1138 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1139 log(LOG_DEBUG, "%s; %s: Listen socket: " 1140 "Socket allocation failed due to " 1141 "limits or memory shortage, %s\n", 1142 s, __func__, 1143 V_tcp_sc_rst_sock_fail ? 1144 "sending RST" : "try again"); 1145 if (V_tcp_sc_rst_sock_fail) { 1146 rstreason = BANDLIM_UNLIMITED; 1147 goto dropwithreset; 1148 } else 1149 goto dropunlock; 1150 } 1151 /* 1152 * Socket is created in state SYN_RECEIVED. 1153 * Unlock the listen socket, lock the newly 1154 * created socket and update the tp variable. 1155 * If we came here via jump to tfo_socket_result, 1156 * then listening socket is read-locked. 1157 */ 1158 INP_UNLOCK(inp); /* listen socket */ 1159 inp = sotoinpcb(so); 1160 /* 1161 * New connection inpcb is already locked by 1162 * syncache_expand(). 1163 */ 1164 INP_WLOCK_ASSERT(inp); 1165 tp = intotcpcb(inp); 1166 KASSERT(tp->t_state == TCPS_SYN_RECEIVED, 1167 ("%s: ", __func__)); 1168 /* 1169 * Process the segment and the data it 1170 * contains. tcp_do_segment() consumes 1171 * the mbuf chain and unlocks the inpcb. 1172 */ 1173 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1174 tp->t_fb->tfb_tcp_do_segment(tp, m, th, drop_hdrlen, 1175 tlen, iptos); 1176 return (IPPROTO_DONE); 1177 } 1178 /* 1179 * Segment flag validation for new connection attempts: 1180 * 1181 * Our (SYN|ACK) response was rejected. 1182 * Check with syncache and remove entry to prevent 1183 * retransmits. 1184 * 1185 * NB: syncache_chkrst does its own logging of failure 1186 * causes. 1187 */ 1188 if (thflags & TH_RST) { 1189 syncache_chkrst(&inc, th, m, port); 1190 goto dropunlock; 1191 } 1192 /* 1193 * We can't do anything without SYN. 1194 */ 1195 if ((thflags & TH_SYN) == 0) { 1196 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1197 log(LOG_DEBUG, "%s; %s: Listen socket: " 1198 "SYN is missing, segment ignored\n", 1199 s, __func__); 1200 TCPSTAT_INC(tcps_badsyn); 1201 goto dropunlock; 1202 } 1203 /* 1204 * (SYN|ACK) is bogus on a listen socket. 1205 */ 1206 if (thflags & TH_ACK) { 1207 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1208 log(LOG_DEBUG, "%s; %s: Listen socket: " 1209 "SYN|ACK invalid, segment rejected\n", 1210 s, __func__); 1211 syncache_badack(&inc, port); /* XXX: Not needed! */ 1212 TCPSTAT_INC(tcps_badsyn); 1213 rstreason = BANDLIM_RST_OPENPORT; 1214 goto dropwithreset; 1215 } 1216 /* 1217 * If the drop_synfin option is enabled, drop all 1218 * segments with both the SYN and FIN bits set. 1219 * This prevents e.g. nmap from identifying the 1220 * TCP/IP stack. 1221 * XXX: Poor reasoning. nmap has other methods 1222 * and is constantly refining its stack detection 1223 * strategies. 1224 * XXX: This is a violation of the TCP specification 1225 * and was used by RFC1644. 1226 */ 1227 if ((thflags & TH_FIN) && V_drop_synfin) { 1228 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1229 log(LOG_DEBUG, "%s; %s: Listen socket: " 1230 "SYN|FIN segment ignored (based on " 1231 "sysctl setting)\n", s, __func__); 1232 TCPSTAT_INC(tcps_badsyn); 1233 goto dropunlock; 1234 } 1235 /* 1236 * Segment's flags are (SYN) or (SYN|FIN). 1237 * 1238 * TH_PUSH, TH_URG, TH_ECE, TH_CWR are ignored 1239 * as they do not affect the state of the TCP FSM. 1240 * The data pointed to by TH_URG and th_urp is ignored. 1241 */ 1242 KASSERT((thflags & (TH_RST|TH_ACK)) == 0, 1243 ("%s: Listen socket: TH_RST or TH_ACK set", __func__)); 1244 KASSERT(thflags & (TH_SYN), 1245 ("%s: Listen socket: TH_SYN not set", __func__)); 1246 INP_RLOCK_ASSERT(inp); 1247 #ifdef INET6 1248 /* 1249 * If deprecated address is forbidden, 1250 * we do not accept SYN to deprecated interface 1251 * address to prevent any new inbound connection from 1252 * getting established. 1253 * When we do not accept SYN, we send a TCP RST, 1254 * with deprecated source address (instead of dropping 1255 * it). We compromise it as it is much better for peer 1256 * to send a RST, and RST will be the final packet 1257 * for the exchange. 1258 * 1259 * If we do not forbid deprecated addresses, we accept 1260 * the SYN packet. RFC2462 does not suggest dropping 1261 * SYN in this case. 1262 * If we decipher RFC2462 5.5.4, it says like this: 1263 * 1. use of deprecated addr with existing 1264 * communication is okay - "SHOULD continue to be 1265 * used" 1266 * 2. use of it with new communication: 1267 * (2a) "SHOULD NOT be used if alternate address 1268 * with sufficient scope is available" 1269 * (2b) nothing mentioned otherwise. 1270 * Here we fall into (2b) case as we have no choice in 1271 * our source address selection - we must obey the peer. 1272 * 1273 * The wording in RFC2462 is confusing, and there are 1274 * multiple description text for deprecated address 1275 * handling - worse, they are not exactly the same. 1276 * I believe 5.5.4 is the best one, so we follow 5.5.4. 1277 */ 1278 if (isipv6 && !V_ip6_use_deprecated) { 1279 struct in6_ifaddr *ia6; 1280 1281 ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */, false); 1282 if (ia6 != NULL && 1283 (ia6->ia6_flags & IN6_IFF_DEPRECATED)) { 1284 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1285 log(LOG_DEBUG, "%s; %s: Listen socket: " 1286 "Connection attempt to deprecated " 1287 "IPv6 address rejected\n", 1288 s, __func__); 1289 rstreason = BANDLIM_RST_OPENPORT; 1290 goto dropwithreset; 1291 } 1292 } 1293 #endif /* INET6 */ 1294 /* 1295 * Basic sanity checks on incoming SYN requests: 1296 * Don't respond if the destination is a link layer 1297 * broadcast according to RFC1122 4.2.3.10, p. 104. 1298 * If it is from this socket it must be forged. 1299 * Don't respond if the source or destination is a 1300 * global or subnet broad- or multicast address. 1301 * Note that it is quite possible to receive unicast 1302 * link-layer packets with a broadcast IP address. Use 1303 * in_broadcast() to find them. 1304 */ 1305 if (m->m_flags & (M_BCAST|M_MCAST)) { 1306 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1307 log(LOG_DEBUG, "%s; %s: Listen socket: " 1308 "Connection attempt from broad- or multicast " 1309 "link layer address ignored\n", s, __func__); 1310 goto dropunlock; 1311 } 1312 #ifdef INET6 1313 if (isipv6) { 1314 if (th->th_dport == th->th_sport && 1315 IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &ip6->ip6_src)) { 1316 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1317 log(LOG_DEBUG, "%s; %s: Listen socket: " 1318 "Connection attempt to/from self " 1319 "ignored\n", s, __func__); 1320 goto dropunlock; 1321 } 1322 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 1323 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) { 1324 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1325 log(LOG_DEBUG, "%s; %s: Listen socket: " 1326 "Connection attempt from/to multicast " 1327 "address ignored\n", s, __func__); 1328 goto dropunlock; 1329 } 1330 } 1331 #endif 1332 #if defined(INET) && defined(INET6) 1333 else 1334 #endif 1335 #ifdef INET 1336 { 1337 if (th->th_dport == th->th_sport && 1338 ip->ip_dst.s_addr == ip->ip_src.s_addr) { 1339 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1340 log(LOG_DEBUG, "%s; %s: Listen socket: " 1341 "Connection attempt from/to self " 1342 "ignored\n", s, __func__); 1343 goto dropunlock; 1344 } 1345 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || 1346 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 1347 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || 1348 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) { 1349 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1350 log(LOG_DEBUG, "%s; %s: Listen socket: " 1351 "Connection attempt from/to broad- " 1352 "or multicast address ignored\n", 1353 s, __func__); 1354 goto dropunlock; 1355 } 1356 } 1357 #endif 1358 /* 1359 * SYN appears to be valid. Create compressed TCP state 1360 * for syncache. 1361 */ 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(tp, m, th, 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(tptoinpcb(tp)); 1514 1515 if (tp->t_flags & TF_WAKESOR) { 1516 struct socket *so = tptosocket(tp); 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 tcpcb *tp, struct mbuf *m, struct tcphdr *th, 1526 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 inpcb *inp = tptoinpcb(tp); 1535 struct socket *so = tptosocket(tp); 1536 struct in_conninfo *inc = &inp->inp_inc; 1537 struct mbuf *mfree; 1538 struct tcpopt to; 1539 int tfo_syn; 1540 u_int maxseg; 1541 1542 thflags = tcp_get_flags(th); 1543 tp->sackhint.last_sack_ack = 0; 1544 sack_changed = 0; 1545 nsegs = max(1, m->m_pkthdr.lro_nsegs); 1546 1547 NET_EPOCH_ASSERT(); 1548 INP_WLOCK_ASSERT(inp); 1549 KASSERT(tp->t_state > TCPS_LISTEN, ("%s: TCPS_LISTEN", 1550 __func__)); 1551 KASSERT(tp->t_state != TCPS_TIME_WAIT, ("%s: TCPS_TIME_WAIT", 1552 __func__)); 1553 1554 #ifdef TCPPCAP 1555 /* Save segment, if requested. */ 1556 tcp_pcap_add(th, m, &(tp->t_inpkts)); 1557 #endif 1558 TCP_LOG_EVENT(tp, th, &so->so_rcv, &so->so_snd, TCP_LOG_IN, 0, 1559 tlen, NULL, true); 1560 1561 if ((thflags & TH_SYN) && (thflags & TH_FIN) && V_drop_synfin) { 1562 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1563 log(LOG_DEBUG, "%s; %s: " 1564 "SYN|FIN segment ignored (based on " 1565 "sysctl setting)\n", s, __func__); 1566 free(s, M_TCPLOG); 1567 } 1568 goto drop; 1569 } 1570 1571 /* 1572 * If a segment with the ACK-bit set arrives in the SYN-SENT state 1573 * check SEQ.ACK first. 1574 */ 1575 if ((tp->t_state == TCPS_SYN_SENT) && (thflags & TH_ACK) && 1576 (SEQ_LEQ(th->th_ack, tp->iss) || SEQ_GT(th->th_ack, tp->snd_max))) { 1577 rstreason = BANDLIM_UNLIMITED; 1578 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 1579 goto dropwithreset; 1580 } 1581 1582 /* 1583 * Segment received on connection. 1584 * Reset idle time and keep-alive timer. 1585 * XXX: This should be done after segment 1586 * validation to ignore broken/spoofed segs. 1587 */ 1588 if (tp->t_idle_reduce && 1589 (tp->snd_max == tp->snd_una) && 1590 ((ticks - tp->t_rcvtime) >= tp->t_rxtcur)) 1591 cc_after_idle(tp); 1592 tp->t_rcvtime = ticks; 1593 1594 if (thflags & TH_FIN) 1595 tcp_log_end_status(tp, TCP_EI_STATUS_CLIENT_FIN); 1596 /* 1597 * Scale up the window into a 32-bit value. 1598 * For the SYN_SENT state the scale is zero. 1599 */ 1600 tiwin = th->th_win << tp->snd_scale; 1601 #ifdef STATS 1602 stats_voi_update_abs_ulong(tp->t_stats, VOI_TCP_FRWIN, tiwin); 1603 #endif 1604 1605 /* 1606 * TCP ECN processing. 1607 */ 1608 if (tcp_ecn_input_segment(tp, thflags, tlen, 1609 tcp_packets_this_ack(tp, th->th_ack), 1610 iptos)) 1611 cc_cong_signal(tp, th, CC_ECN); 1612 1613 /* 1614 * Parse options on any incoming segment. 1615 */ 1616 tcp_dooptions(&to, (u_char *)(th + 1), 1617 (th->th_off << 2) - sizeof(struct tcphdr), 1618 (thflags & TH_SYN) ? TO_SYN : 0); 1619 1620 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 1621 if ((tp->t_flags & TF_SIGNATURE) != 0 && 1622 (to.to_flags & TOF_SIGNATURE) == 0) { 1623 TCPSTAT_INC(tcps_sig_err_sigopt); 1624 /* XXX: should drop? */ 1625 } 1626 #endif 1627 /* 1628 * If echoed timestamp is later than the current time, 1629 * fall back to non RFC1323 RTT calculation. Normalize 1630 * timestamp if syncookies were used when this connection 1631 * was established. 1632 */ 1633 if ((to.to_flags & TOF_TS) && (to.to_tsecr != 0)) { 1634 to.to_tsecr -= tp->ts_offset; 1635 if (TSTMP_GT(to.to_tsecr, tcp_ts_getticks())) 1636 to.to_tsecr = 0; 1637 else if (tp->t_rxtshift == 1 && 1638 tp->t_flags & TF_PREVVALID && 1639 tp->t_badrxtwin != 0 && 1640 TSTMP_LT(to.to_tsecr, tp->t_badrxtwin)) 1641 cc_cong_signal(tp, th, CC_RTO_ERR); 1642 } 1643 /* 1644 * Process options only when we get SYN/ACK back. The SYN case 1645 * for incoming connections is handled in tcp_syncache. 1646 * According to RFC1323 the window field in a SYN (i.e., a <SYN> 1647 * or <SYN,ACK>) segment itself is never scaled. 1648 * XXX this is traditional behavior, may need to be cleaned up. 1649 */ 1650 if (tp->t_state == TCPS_SYN_SENT && (thflags & TH_SYN)) { 1651 /* Handle parallel SYN for ECN */ 1652 tcp_ecn_input_parallel_syn(tp, thflags, iptos); 1653 if ((to.to_flags & TOF_SCALE) && 1654 (tp->t_flags & TF_REQ_SCALE) && 1655 !(tp->t_flags & TF_NOOPT)) { 1656 tp->t_flags |= TF_RCVD_SCALE; 1657 tp->snd_scale = to.to_wscale; 1658 } else 1659 tp->t_flags &= ~TF_REQ_SCALE; 1660 /* 1661 * Initial send window. It will be updated with 1662 * the next incoming segment to the scaled value. 1663 */ 1664 tp->snd_wnd = th->th_win; 1665 if ((to.to_flags & TOF_TS) && 1666 (tp->t_flags & TF_REQ_TSTMP) && 1667 !(tp->t_flags & TF_NOOPT)) { 1668 tp->t_flags |= TF_RCVD_TSTMP; 1669 tp->ts_recent = to.to_tsval; 1670 tp->ts_recent_age = tcp_ts_getticks(); 1671 } else 1672 tp->t_flags &= ~TF_REQ_TSTMP; 1673 if (to.to_flags & TOF_MSS) 1674 tcp_mss(tp, to.to_mss); 1675 if ((tp->t_flags & TF_SACK_PERMIT) && 1676 (!(to.to_flags & TOF_SACKPERM) || 1677 (tp->t_flags & TF_NOOPT))) 1678 tp->t_flags &= ~TF_SACK_PERMIT; 1679 if (IS_FASTOPEN(tp->t_flags)) { 1680 if ((to.to_flags & TOF_FASTOPEN) && 1681 !(tp->t_flags & TF_NOOPT)) { 1682 uint16_t mss; 1683 1684 if (to.to_flags & TOF_MSS) 1685 mss = to.to_mss; 1686 else 1687 if ((inp->inp_vflag & INP_IPV6) != 0) 1688 mss = TCP6_MSS; 1689 else 1690 mss = TCP_MSS; 1691 tcp_fastopen_update_cache(tp, mss, 1692 to.to_tfo_len, to.to_tfo_cookie); 1693 } else 1694 tcp_fastopen_disable_path(tp); 1695 } 1696 } 1697 1698 /* 1699 * If timestamps were negotiated during SYN/ACK and a 1700 * segment without a timestamp is received, silently drop 1701 * the segment, unless it is a RST segment or missing timestamps are 1702 * tolerated. 1703 * See section 3.2 of RFC 7323. 1704 */ 1705 if ((tp->t_flags & TF_RCVD_TSTMP) && !(to.to_flags & TOF_TS)) { 1706 if (((thflags & TH_RST) != 0) || V_tcp_tolerate_missing_ts) { 1707 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1708 log(LOG_DEBUG, "%s; %s: Timestamp missing, " 1709 "segment processed normally\n", 1710 s, __func__); 1711 free(s, M_TCPLOG); 1712 } 1713 } else { 1714 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1715 log(LOG_DEBUG, "%s; %s: Timestamp missing, " 1716 "segment silently dropped\n", s, __func__); 1717 free(s, M_TCPLOG); 1718 } 1719 goto drop; 1720 } 1721 } 1722 /* 1723 * If timestamps were not negotiated during SYN/ACK and a 1724 * segment with a timestamp is received, ignore the 1725 * timestamp and process the packet normally. 1726 * See section 3.2 of RFC 7323. 1727 */ 1728 if (!(tp->t_flags & TF_RCVD_TSTMP) && (to.to_flags & TOF_TS)) { 1729 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1730 log(LOG_DEBUG, "%s; %s: Timestamp not expected, " 1731 "segment processed normally\n", s, __func__); 1732 free(s, M_TCPLOG); 1733 } 1734 } 1735 1736 /* 1737 * Header prediction: check for the two common cases 1738 * of a uni-directional data xfer. If the packet has 1739 * no control flags, is in-sequence, the window didn't 1740 * change and we're not retransmitting, it's a 1741 * candidate. If the length is zero and the ack moved 1742 * forward, we're the sender side of the xfer. Just 1743 * free the data acked & wake any higher level process 1744 * that was blocked waiting for space. If the length 1745 * is non-zero and the ack didn't move, we're the 1746 * receiver side. If we're getting packets in-order 1747 * (the reassembly queue is empty), add the data to 1748 * the socket buffer and note that we need a delayed ack. 1749 * Make sure that the hidden state-flags are also off. 1750 * Since we check for TCPS_ESTABLISHED first, it can only 1751 * be TH_NEEDSYN. 1752 */ 1753 if (tp->t_state == TCPS_ESTABLISHED && 1754 th->th_seq == tp->rcv_nxt && 1755 (thflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK && 1756 tp->snd_nxt == tp->snd_max && 1757 tiwin && tiwin == tp->snd_wnd && 1758 ((tp->t_flags & (TF_NEEDSYN|TF_NEEDFIN)) == 0) && 1759 SEGQ_EMPTY(tp) && 1760 ((to.to_flags & TOF_TS) == 0 || 1761 TSTMP_GEQ(to.to_tsval, tp->ts_recent)) ) { 1762 /* 1763 * If last ACK falls within this segment's sequence numbers, 1764 * record the timestamp. 1765 * NOTE that the test is modified according to the latest 1766 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 1767 */ 1768 if ((to.to_flags & TOF_TS) != 0 && 1769 SEQ_LEQ(th->th_seq, tp->last_ack_sent)) { 1770 tp->ts_recent_age = tcp_ts_getticks(); 1771 tp->ts_recent = to.to_tsval; 1772 } 1773 1774 if (tlen == 0) { 1775 if (SEQ_GT(th->th_ack, tp->snd_una) && 1776 SEQ_LEQ(th->th_ack, tp->snd_max) && 1777 !IN_RECOVERY(tp->t_flags) && 1778 (to.to_flags & TOF_SACK) == 0 && 1779 TAILQ_EMPTY(&tp->snd_holes)) { 1780 /* 1781 * This is a pure ack for outstanding data. 1782 */ 1783 TCPSTAT_INC(tcps_predack); 1784 1785 /* 1786 * "bad retransmit" recovery without timestamps. 1787 */ 1788 if ((to.to_flags & TOF_TS) == 0 && 1789 tp->t_rxtshift == 1 && 1790 tp->t_flags & TF_PREVVALID && 1791 tp->t_badrxtwin != 0 && 1792 TSTMP_LT(ticks, tp->t_badrxtwin)) { 1793 cc_cong_signal(tp, th, CC_RTO_ERR); 1794 } 1795 1796 /* 1797 * Recalculate the transmit timer / rtt. 1798 * 1799 * Some boxes send broken timestamp replies 1800 * during the SYN+ACK phase, ignore 1801 * timestamps of 0 or we could calculate a 1802 * huge RTT and blow up the retransmit timer. 1803 */ 1804 if ((to.to_flags & TOF_TS) != 0 && 1805 to.to_tsecr) { 1806 uint32_t t; 1807 1808 t = tcp_ts_getticks() - to.to_tsecr; 1809 if (!tp->t_rttlow || tp->t_rttlow > t) 1810 tp->t_rttlow = t; 1811 tcp_xmit_timer(tp, 1812 TCP_TS_TO_TICKS(t) + 1); 1813 } else if (tp->t_rtttime && 1814 SEQ_GT(th->th_ack, tp->t_rtseq)) { 1815 if (!tp->t_rttlow || 1816 tp->t_rttlow > ticks - tp->t_rtttime) 1817 tp->t_rttlow = ticks - tp->t_rtttime; 1818 tcp_xmit_timer(tp, 1819 ticks - tp->t_rtttime); 1820 } 1821 acked = BYTES_THIS_ACK(tp, th); 1822 1823 #ifdef TCP_HHOOK 1824 /* Run HHOOK_TCP_ESTABLISHED_IN helper hooks. */ 1825 hhook_run_tcp_est_in(tp, th, &to); 1826 #endif 1827 1828 TCPSTAT_ADD(tcps_rcvackpack, nsegs); 1829 TCPSTAT_ADD(tcps_rcvackbyte, acked); 1830 sbdrop(&so->so_snd, acked); 1831 if (SEQ_GT(tp->snd_una, tp->snd_recover) && 1832 SEQ_LEQ(th->th_ack, tp->snd_recover)) 1833 tp->snd_recover = th->th_ack - 1; 1834 1835 /* 1836 * Let the congestion control algorithm update 1837 * congestion control related information. This 1838 * typically means increasing the congestion 1839 * window. 1840 */ 1841 cc_ack_received(tp, th, nsegs, CC_ACK); 1842 1843 tp->snd_una = th->th_ack; 1844 /* 1845 * Pull snd_wl2 up to prevent seq wrap relative 1846 * to th_ack. 1847 */ 1848 tp->snd_wl2 = th->th_ack; 1849 tp->t_dupacks = 0; 1850 m_freem(m); 1851 1852 /* 1853 * If all outstanding data are acked, stop 1854 * retransmit timer, otherwise restart timer 1855 * using current (possibly backed-off) value. 1856 * If process is waiting for space, 1857 * wakeup/selwakeup/signal. If data 1858 * are ready to send, let tcp_output 1859 * decide between more output or persist. 1860 */ 1861 TCP_PROBE3(debug__input, tp, th, m); 1862 /* 1863 * Clear t_acktime if remote side has ACKd 1864 * all data in the socket buffer. 1865 * Otherwise, update t_acktime if we received 1866 * a sufficiently large ACK. 1867 */ 1868 if (sbavail(&so->so_snd) == 0) 1869 tp->t_acktime = 0; 1870 else if (acked > 1) 1871 tp->t_acktime = ticks; 1872 if (tp->snd_una == tp->snd_max) 1873 tcp_timer_activate(tp, TT_REXMT, 0); 1874 else if (!tcp_timer_active(tp, TT_PERSIST)) 1875 tcp_timer_activate(tp, TT_REXMT, 1876 TP_RXTCUR(tp)); 1877 sowwakeup(so); 1878 if (sbavail(&so->so_snd)) 1879 (void) tcp_output(tp); 1880 goto check_delack; 1881 } 1882 } else if (th->th_ack == tp->snd_una && 1883 tlen <= sbspace(&so->so_rcv)) { 1884 int newsize = 0; /* automatic sockbuf scaling */ 1885 1886 /* 1887 * This is a pure, in-sequence data packet with 1888 * nothing on the reassembly queue and we have enough 1889 * buffer space to take it. 1890 */ 1891 /* Clean receiver SACK report if present */ 1892 if ((tp->t_flags & TF_SACK_PERMIT) && tp->rcv_numsacks) 1893 tcp_clean_sackreport(tp); 1894 TCPSTAT_INC(tcps_preddat); 1895 tp->rcv_nxt += tlen; 1896 if (tlen && 1897 ((tp->t_flags2 & TF2_FBYTES_COMPLETE) == 0) && 1898 (tp->t_fbyte_in == 0)) { 1899 tp->t_fbyte_in = ticks; 1900 if (tp->t_fbyte_in == 0) 1901 tp->t_fbyte_in = 1; 1902 if (tp->t_fbyte_out && tp->t_fbyte_in) 1903 tp->t_flags2 |= TF2_FBYTES_COMPLETE; 1904 } 1905 /* 1906 * Pull snd_wl1 up to prevent seq wrap relative to 1907 * th_seq. 1908 */ 1909 tp->snd_wl1 = th->th_seq; 1910 /* 1911 * Pull rcv_up up to prevent seq wrap relative to 1912 * rcv_nxt. 1913 */ 1914 tp->rcv_up = tp->rcv_nxt; 1915 TCPSTAT_ADD(tcps_rcvpack, nsegs); 1916 TCPSTAT_ADD(tcps_rcvbyte, tlen); 1917 TCP_PROBE3(debug__input, tp, th, m); 1918 1919 newsize = tcp_autorcvbuf(m, th, so, tp, tlen); 1920 1921 /* Add data to socket buffer. */ 1922 SOCKBUF_LOCK(&so->so_rcv); 1923 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 1924 m_freem(m); 1925 } else { 1926 /* 1927 * Set new socket buffer size. 1928 * Give up when limit is reached. 1929 */ 1930 if (newsize) 1931 if (!sbreserve_locked(so, SO_RCV, 1932 newsize, NULL)) 1933 so->so_rcv.sb_flags &= ~SB_AUTOSIZE; 1934 m_adj(m, drop_hdrlen); /* delayed header drop */ 1935 sbappendstream_locked(&so->so_rcv, m, 0); 1936 } 1937 /* NB: sorwakeup_locked() does an implicit unlock. */ 1938 sorwakeup_locked(so); 1939 if (DELAY_ACK(tp, tlen)) { 1940 tp->t_flags |= TF_DELACK; 1941 } else { 1942 tp->t_flags |= TF_ACKNOW; 1943 tcp_output(tp); 1944 } 1945 goto check_delack; 1946 } 1947 } 1948 1949 /* 1950 * Calculate amount of space in receive window, 1951 * and then do TCP input processing. 1952 * Receive window is amount of space in rcv queue, 1953 * but not less than advertised window. 1954 */ 1955 win = sbspace(&so->so_rcv); 1956 if (win < 0) 1957 win = 0; 1958 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 1959 1960 switch (tp->t_state) { 1961 /* 1962 * If the state is SYN_RECEIVED: 1963 * if seg contains an ACK, but not for our SYN/ACK, send a RST. 1964 */ 1965 case TCPS_SYN_RECEIVED: 1966 if (thflags & TH_RST) { 1967 /* Handle RST segments later. */ 1968 break; 1969 } 1970 if ((thflags & TH_ACK) && 1971 (SEQ_LEQ(th->th_ack, tp->snd_una) || 1972 SEQ_GT(th->th_ack, tp->snd_max))) { 1973 rstreason = BANDLIM_RST_OPENPORT; 1974 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 1975 goto dropwithreset; 1976 } 1977 if (IS_FASTOPEN(tp->t_flags)) { 1978 /* 1979 * When a TFO connection is in SYN_RECEIVED, the 1980 * only valid packets are the initial SYN, a 1981 * retransmit/copy of the initial SYN (possibly with 1982 * a subset of the original data), a valid ACK, a 1983 * FIN, or a RST. 1984 */ 1985 if ((thflags & (TH_SYN|TH_ACK)) == (TH_SYN|TH_ACK)) { 1986 rstreason = BANDLIM_RST_OPENPORT; 1987 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 1988 goto dropwithreset; 1989 } else if (thflags & TH_SYN) { 1990 /* non-initial SYN is ignored */ 1991 if ((tcp_timer_active(tp, TT_DELACK) || 1992 tcp_timer_active(tp, TT_REXMT))) 1993 goto drop; 1994 } else if (!(thflags & (TH_ACK|TH_FIN|TH_RST))) { 1995 goto drop; 1996 } 1997 } 1998 break; 1999 2000 /* 2001 * If the state is SYN_SENT: 2002 * if seg contains a RST with valid ACK (SEQ.ACK has already 2003 * been verified), then drop the connection. 2004 * if seg contains a RST without an ACK, drop the seg. 2005 * if seg does not contain SYN, then drop the seg. 2006 * Otherwise this is an acceptable SYN segment 2007 * initialize tp->rcv_nxt and tp->irs 2008 * if seg contains ack then advance tp->snd_una 2009 * if seg contains an ECE and ECN support is enabled, the stream 2010 * is ECN capable. 2011 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 2012 * arrange for segment to be acked (eventually) 2013 * continue processing rest of data/controls, beginning with URG 2014 */ 2015 case TCPS_SYN_SENT: 2016 if ((thflags & (TH_ACK|TH_RST)) == (TH_ACK|TH_RST)) { 2017 TCP_PROBE5(connect__refused, NULL, tp, 2018 m, tp, th); 2019 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 2020 tp = tcp_drop(tp, ECONNREFUSED); 2021 } 2022 if (thflags & TH_RST) 2023 goto drop; 2024 if (!(thflags & TH_SYN)) 2025 goto drop; 2026 2027 tp->irs = th->th_seq; 2028 tcp_rcvseqinit(tp); 2029 if (thflags & TH_ACK) { 2030 int tfo_partial_ack = 0; 2031 2032 TCPSTAT_INC(tcps_connects); 2033 soisconnected(so); 2034 #ifdef MAC 2035 mac_socketpeer_set_from_mbuf(m, so); 2036 #endif 2037 /* Do window scaling on this connection? */ 2038 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2039 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2040 tp->rcv_scale = tp->request_r_scale; 2041 } 2042 tp->rcv_adv += min(tp->rcv_wnd, 2043 TCP_MAXWIN << tp->rcv_scale); 2044 tp->snd_una++; /* SYN is acked */ 2045 /* 2046 * If not all the data that was sent in the TFO SYN 2047 * has been acked, resend the remainder right away. 2048 */ 2049 if (IS_FASTOPEN(tp->t_flags) && 2050 (tp->snd_una != tp->snd_max)) { 2051 tp->snd_nxt = th->th_ack; 2052 tfo_partial_ack = 1; 2053 } 2054 /* 2055 * If there's data, delay ACK; if there's also a FIN 2056 * ACKNOW will be turned on later. 2057 */ 2058 if (DELAY_ACK(tp, tlen) && tlen != 0 && !tfo_partial_ack) 2059 tcp_timer_activate(tp, TT_DELACK, 2060 tcp_delacktime); 2061 else 2062 tp->t_flags |= TF_ACKNOW; 2063 2064 tcp_ecn_input_syn_sent(tp, thflags, iptos); 2065 2066 /* 2067 * Received <SYN,ACK> in SYN_SENT[*] state. 2068 * Transitions: 2069 * SYN_SENT --> ESTABLISHED 2070 * SYN_SENT* --> FIN_WAIT_1 2071 */ 2072 tp->t_starttime = ticks; 2073 if (tp->t_flags & TF_NEEDFIN) { 2074 tp->t_acktime = ticks; 2075 tcp_state_change(tp, TCPS_FIN_WAIT_1); 2076 tp->t_flags &= ~TF_NEEDFIN; 2077 thflags &= ~TH_SYN; 2078 } else { 2079 tcp_state_change(tp, TCPS_ESTABLISHED); 2080 TCP_PROBE5(connect__established, NULL, tp, 2081 m, tp, th); 2082 cc_conn_init(tp); 2083 tcp_timer_activate(tp, TT_KEEP, 2084 TP_KEEPIDLE(tp)); 2085 } 2086 } else { 2087 /* 2088 * Received initial SYN in SYN-SENT[*] state => 2089 * simultaneous open. 2090 * If it succeeds, connection is * half-synchronized. 2091 * Otherwise, do 3-way handshake: 2092 * SYN-SENT -> SYN-RECEIVED 2093 * SYN-SENT* -> SYN-RECEIVED* 2094 */ 2095 tp->t_flags |= (TF_ACKNOW | TF_NEEDSYN | TF_SONOTCONN); 2096 tcp_timer_activate(tp, TT_REXMT, 0); 2097 tcp_state_change(tp, TCPS_SYN_RECEIVED); 2098 } 2099 2100 /* 2101 * Advance th->th_seq to correspond to first data byte. 2102 * If data, trim to stay within window, 2103 * dropping FIN if necessary. 2104 */ 2105 th->th_seq++; 2106 if (tlen > tp->rcv_wnd) { 2107 todrop = tlen - tp->rcv_wnd; 2108 m_adj(m, -todrop); 2109 tlen = tp->rcv_wnd; 2110 thflags &= ~TH_FIN; 2111 TCPSTAT_INC(tcps_rcvpackafterwin); 2112 TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); 2113 } 2114 tp->snd_wl1 = th->th_seq - 1; 2115 tp->rcv_up = th->th_seq; 2116 /* 2117 * Client side of transaction: already sent SYN and data. 2118 * If the remote host used T/TCP to validate the SYN, 2119 * our data will be ACK'd; if so, enter normal data segment 2120 * processing in the middle of step 5, ack processing. 2121 * Otherwise, goto step 6. 2122 */ 2123 if (thflags & TH_ACK) 2124 goto process_ACK; 2125 2126 goto step6; 2127 } 2128 2129 /* 2130 * States other than LISTEN or SYN_SENT. 2131 * First check the RST flag and sequence number since reset segments 2132 * are exempt from the timestamp and connection count tests. This 2133 * fixes a bug introduced by the Stevens, vol. 2, p. 960 bugfix 2134 * below which allowed reset segments in half the sequence space 2135 * to fall though and be processed (which gives forged reset 2136 * segments with a random sequence number a 50 percent chance of 2137 * killing a connection). 2138 * Then check timestamp, if present. 2139 * Then check the connection count, if present. 2140 * Then check that at least some bytes of segment are within 2141 * receive window. If segment begins before rcv_nxt, 2142 * drop leading data (and SYN); if nothing left, just ack. 2143 */ 2144 if (thflags & TH_RST) { 2145 /* 2146 * RFC5961 Section 3.2 2147 * 2148 * - RST drops connection only if SEG.SEQ == RCV.NXT. 2149 * - If RST is in window, we send challenge ACK. 2150 * 2151 * Note: to take into account delayed ACKs, we should 2152 * test against last_ack_sent instead of rcv_nxt. 2153 * Note 2: we handle special case of closed window, not 2154 * covered by the RFC. 2155 */ 2156 if ((SEQ_GEQ(th->th_seq, tp->last_ack_sent) && 2157 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) || 2158 (tp->rcv_wnd == 0 && tp->last_ack_sent == th->th_seq)) { 2159 KASSERT(tp->t_state != TCPS_SYN_SENT, 2160 ("%s: TH_RST for TCPS_SYN_SENT th %p tp %p", 2161 __func__, th, tp)); 2162 2163 if (V_tcp_insecure_rst || 2164 tp->last_ack_sent == th->th_seq) { 2165 TCPSTAT_INC(tcps_drops); 2166 /* Drop the connection. */ 2167 switch (tp->t_state) { 2168 case TCPS_SYN_RECEIVED: 2169 so->so_error = ECONNREFUSED; 2170 goto close; 2171 case TCPS_ESTABLISHED: 2172 case TCPS_FIN_WAIT_1: 2173 case TCPS_FIN_WAIT_2: 2174 case TCPS_CLOSE_WAIT: 2175 case TCPS_CLOSING: 2176 case TCPS_LAST_ACK: 2177 so->so_error = ECONNRESET; 2178 close: 2179 /* FALLTHROUGH */ 2180 default: 2181 tcp_log_end_status(tp, TCP_EI_STATUS_CLIENT_RST); 2182 tp = tcp_close(tp); 2183 } 2184 } else { 2185 TCPSTAT_INC(tcps_badrst); 2186 /* Send challenge ACK. */ 2187 tcp_respond(tp, mtod(m, void *), th, m, 2188 tp->rcv_nxt, tp->snd_nxt, TH_ACK); 2189 tp->last_ack_sent = tp->rcv_nxt; 2190 m = NULL; 2191 } 2192 } 2193 goto drop; 2194 } 2195 2196 /* 2197 * RFC5961 Section 4.2 2198 * Send challenge ACK for any SYN in synchronized state. 2199 */ 2200 if ((thflags & TH_SYN) && tp->t_state != TCPS_SYN_SENT && 2201 tp->t_state != TCPS_SYN_RECEIVED) { 2202 TCPSTAT_INC(tcps_badsyn); 2203 if (V_tcp_insecure_syn && 2204 SEQ_GEQ(th->th_seq, tp->last_ack_sent) && 2205 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) { 2206 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 2207 tp = tcp_drop(tp, ECONNRESET); 2208 rstreason = BANDLIM_UNLIMITED; 2209 } else { 2210 tcp_ecn_input_syn_sent(tp, thflags, iptos); 2211 /* Send challenge ACK. */ 2212 tcp_respond(tp, mtod(m, void *), th, m, tp->rcv_nxt, 2213 tp->snd_nxt, TH_ACK); 2214 tp->last_ack_sent = tp->rcv_nxt; 2215 m = NULL; 2216 } 2217 goto drop; 2218 } 2219 2220 /* 2221 * RFC 1323 PAWS: If we have a timestamp reply on this segment 2222 * and it's less than ts_recent, drop it. 2223 */ 2224 if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent && 2225 TSTMP_LT(to.to_tsval, tp->ts_recent)) { 2226 /* Check to see if ts_recent is over 24 days old. */ 2227 if (tcp_ts_getticks() - tp->ts_recent_age > TCP_PAWS_IDLE) { 2228 /* 2229 * Invalidate ts_recent. If this segment updates 2230 * ts_recent, the age will be reset later and ts_recent 2231 * will get a valid value. If it does not, setting 2232 * ts_recent to zero will at least satisfy the 2233 * requirement that zero be placed in the timestamp 2234 * echo reply when ts_recent isn't valid. The 2235 * age isn't reset until we get a valid ts_recent 2236 * because we don't want out-of-order segments to be 2237 * dropped when ts_recent is old. 2238 */ 2239 tp->ts_recent = 0; 2240 } else { 2241 TCPSTAT_INC(tcps_rcvduppack); 2242 TCPSTAT_ADD(tcps_rcvdupbyte, tlen); 2243 TCPSTAT_INC(tcps_pawsdrop); 2244 if (tlen) 2245 goto dropafterack; 2246 goto drop; 2247 } 2248 } 2249 2250 /* 2251 * In the SYN-RECEIVED state, validate that the packet belongs to 2252 * this connection before trimming the data to fit the receive 2253 * window. Check the sequence number versus IRS since we know 2254 * the sequence numbers haven't wrapped. This is a partial fix 2255 * for the "LAND" DoS attack. 2256 */ 2257 if (tp->t_state == TCPS_SYN_RECEIVED && SEQ_LT(th->th_seq, tp->irs)) { 2258 rstreason = BANDLIM_RST_OPENPORT; 2259 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 2260 goto dropwithreset; 2261 } 2262 2263 todrop = tp->rcv_nxt - th->th_seq; 2264 if (todrop > 0) { 2265 if (thflags & TH_SYN) { 2266 thflags &= ~TH_SYN; 2267 th->th_seq++; 2268 if (th->th_urp > 1) 2269 th->th_urp--; 2270 else 2271 thflags &= ~TH_URG; 2272 todrop--; 2273 } 2274 /* 2275 * Following if statement from Stevens, vol. 2, p. 960. 2276 */ 2277 if (todrop > tlen 2278 || (todrop == tlen && (thflags & TH_FIN) == 0)) { 2279 /* 2280 * Any valid FIN must be to the left of the window. 2281 * At this point the FIN must be a duplicate or out 2282 * of sequence; drop it. 2283 */ 2284 thflags &= ~TH_FIN; 2285 2286 /* 2287 * Send an ACK to resynchronize and drop any data. 2288 * But keep on processing for RST or ACK. 2289 */ 2290 tp->t_flags |= TF_ACKNOW; 2291 todrop = tlen; 2292 TCPSTAT_INC(tcps_rcvduppack); 2293 TCPSTAT_ADD(tcps_rcvdupbyte, todrop); 2294 } else { 2295 TCPSTAT_INC(tcps_rcvpartduppack); 2296 TCPSTAT_ADD(tcps_rcvpartdupbyte, todrop); 2297 } 2298 /* 2299 * DSACK - add SACK block for dropped range 2300 */ 2301 if ((todrop > 0) && (tp->t_flags & TF_SACK_PERMIT)) { 2302 tcp_update_sack_list(tp, th->th_seq, 2303 th->th_seq + todrop); 2304 /* 2305 * ACK now, as the next in-sequence segment 2306 * will clear the DSACK block again 2307 */ 2308 tp->t_flags |= TF_ACKNOW; 2309 } 2310 drop_hdrlen += todrop; /* drop from the top afterwards */ 2311 th->th_seq += todrop; 2312 tlen -= todrop; 2313 if (th->th_urp > todrop) 2314 th->th_urp -= todrop; 2315 else { 2316 thflags &= ~TH_URG; 2317 th->th_urp = 0; 2318 } 2319 } 2320 2321 /* 2322 * If new data are received on a connection after the 2323 * user processes are gone, then RST the other end. 2324 */ 2325 if ((tp->t_flags & TF_CLOSED) && tlen) { 2326 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 2327 log(LOG_DEBUG, "%s; %s: %s: Received %d bytes of data " 2328 "after socket was closed, " 2329 "sending RST and removing tcpcb\n", 2330 s, __func__, tcpstates[tp->t_state], tlen); 2331 free(s, M_TCPLOG); 2332 } 2333 tcp_log_end_status(tp, TCP_EI_STATUS_DATA_A_CLOSE); 2334 /* tcp_close will kill the inp pre-log the Reset */ 2335 tcp_log_end_status(tp, TCP_EI_STATUS_SERVER_RST); 2336 tp = tcp_close(tp); 2337 TCPSTAT_INC(tcps_rcvafterclose); 2338 rstreason = BANDLIM_UNLIMITED; 2339 goto dropwithreset; 2340 } 2341 2342 /* 2343 * If segment ends after window, drop trailing data 2344 * (and PUSH and FIN); if nothing left, just ACK. 2345 */ 2346 todrop = (th->th_seq + tlen) - (tp->rcv_nxt + tp->rcv_wnd); 2347 if (todrop > 0) { 2348 TCPSTAT_INC(tcps_rcvpackafterwin); 2349 if (todrop >= tlen) { 2350 TCPSTAT_ADD(tcps_rcvbyteafterwin, tlen); 2351 /* 2352 * If window is closed can only take segments at 2353 * window edge, and have to drop data and PUSH from 2354 * incoming segments. Continue processing, but 2355 * remember to ack. Otherwise, drop segment 2356 * and ack. 2357 */ 2358 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 2359 tp->t_flags |= TF_ACKNOW; 2360 TCPSTAT_INC(tcps_rcvwinprobe); 2361 } else 2362 goto dropafterack; 2363 } else 2364 TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); 2365 m_adj(m, -todrop); 2366 tlen -= todrop; 2367 thflags &= ~(TH_PUSH|TH_FIN); 2368 } 2369 2370 /* 2371 * If last ACK falls within this segment's sequence numbers, 2372 * record its timestamp. 2373 * NOTE: 2374 * 1) That the test incorporates suggestions from the latest 2375 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 2376 * 2) That updating only on newer timestamps interferes with 2377 * our earlier PAWS tests, so this check should be solely 2378 * predicated on the sequence space of this segment. 2379 * 3) That we modify the segment boundary check to be 2380 * Last.ACK.Sent <= SEG.SEQ + SEG.Len 2381 * instead of RFC1323's 2382 * Last.ACK.Sent < SEG.SEQ + SEG.Len, 2383 * This modified check allows us to overcome RFC1323's 2384 * limitations as described in Stevens TCP/IP Illustrated 2385 * Vol. 2 p.869. In such cases, we can still calculate the 2386 * RTT correctly when RCV.NXT == Last.ACK.Sent. 2387 */ 2388 if ((to.to_flags & TOF_TS) != 0 && 2389 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 2390 SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen + 2391 ((thflags & (TH_SYN|TH_FIN)) != 0))) { 2392 tp->ts_recent_age = tcp_ts_getticks(); 2393 tp->ts_recent = to.to_tsval; 2394 } 2395 2396 /* 2397 * If the ACK bit is off: if in SYN-RECEIVED state or SENDSYN 2398 * flag is on (half-synchronized state), then queue data for 2399 * later processing; else drop segment and return. 2400 */ 2401 if ((thflags & TH_ACK) == 0) { 2402 if (tp->t_state == TCPS_SYN_RECEIVED || 2403 (tp->t_flags & TF_NEEDSYN)) { 2404 if (tp->t_state == TCPS_SYN_RECEIVED && 2405 IS_FASTOPEN(tp->t_flags)) { 2406 tp->snd_wnd = tiwin; 2407 cc_conn_init(tp); 2408 } 2409 goto step6; 2410 } else if (tp->t_flags & TF_ACKNOW) 2411 goto dropafterack; 2412 else 2413 goto drop; 2414 } 2415 2416 /* 2417 * Ack processing. 2418 */ 2419 switch (tp->t_state) { 2420 /* 2421 * In SYN_RECEIVED state, the ack ACKs our SYN, so enter 2422 * ESTABLISHED state and continue processing. 2423 * The ACK was checked above. 2424 */ 2425 case TCPS_SYN_RECEIVED: 2426 2427 TCPSTAT_INC(tcps_connects); 2428 if (tp->t_flags & TF_SONOTCONN) { 2429 /* 2430 * Usually SYN_RECEIVED had been created from a LISTEN, 2431 * and solisten_enqueue() has already marked the socket 2432 * layer as connected. If it didn't, which can happen 2433 * only with an accept_filter(9), then the tp is marked 2434 * with TF_SONOTCONN. The other reason for this mark 2435 * to be set is a simultaneous open, a SYN_RECEIVED 2436 * that had been created from SYN_SENT. 2437 */ 2438 tp->t_flags &= ~TF_SONOTCONN; 2439 soisconnected(so); 2440 } 2441 /* Do window scaling? */ 2442 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2443 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2444 tp->rcv_scale = tp->request_r_scale; 2445 } 2446 tp->snd_wnd = tiwin; 2447 /* 2448 * Make transitions: 2449 * SYN-RECEIVED -> ESTABLISHED 2450 * SYN-RECEIVED* -> FIN-WAIT-1 2451 */ 2452 tp->t_starttime = ticks; 2453 if (IS_FASTOPEN(tp->t_flags) && tp->t_tfo_pending) { 2454 tcp_fastopen_decrement_counter(tp->t_tfo_pending); 2455 tp->t_tfo_pending = NULL; 2456 } 2457 if (tp->t_flags & TF_NEEDFIN) { 2458 tp->t_acktime = ticks; 2459 tcp_state_change(tp, TCPS_FIN_WAIT_1); 2460 tp->t_flags &= ~TF_NEEDFIN; 2461 } else { 2462 tcp_state_change(tp, TCPS_ESTABLISHED); 2463 TCP_PROBE5(accept__established, NULL, tp, 2464 m, tp, th); 2465 /* 2466 * TFO connections call cc_conn_init() during SYN 2467 * processing. Calling it again here for such 2468 * connections is not harmless as it would undo the 2469 * snd_cwnd reduction that occurs when a TFO SYN|ACK 2470 * is retransmitted. 2471 */ 2472 if (!IS_FASTOPEN(tp->t_flags)) 2473 cc_conn_init(tp); 2474 tcp_timer_activate(tp, TT_KEEP, TP_KEEPIDLE(tp)); 2475 } 2476 /* 2477 * Account for the ACK of our SYN prior to 2478 * regular ACK processing below, except for 2479 * simultaneous SYN, which is handled later. 2480 */ 2481 if (SEQ_GT(th->th_ack, tp->snd_una) && !(tp->t_flags & TF_NEEDSYN)) 2482 incforsyn = 1; 2483 /* 2484 * If segment contains data or ACK, will call tcp_reass() 2485 * later; if not, do so now to pass queued data to user. 2486 */ 2487 if (tlen == 0 && (thflags & TH_FIN) == 0) { 2488 (void) tcp_reass(tp, (struct tcphdr *)0, NULL, 0, 2489 (struct mbuf *)0); 2490 tcp_handle_wakeup(tp); 2491 } 2492 tp->snd_wl1 = th->th_seq - 1; 2493 /* FALLTHROUGH */ 2494 2495 /* 2496 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 2497 * ACKs. If the ack is in the range 2498 * tp->snd_una < th->th_ack <= tp->snd_max 2499 * then advance tp->snd_una to th->th_ack and drop 2500 * data from the retransmission queue. If this ACK reflects 2501 * more up to date window information we update our window information. 2502 */ 2503 case TCPS_ESTABLISHED: 2504 case TCPS_FIN_WAIT_1: 2505 case TCPS_FIN_WAIT_2: 2506 case TCPS_CLOSE_WAIT: 2507 case TCPS_CLOSING: 2508 case TCPS_LAST_ACK: 2509 if (SEQ_GT(th->th_ack, tp->snd_max)) { 2510 TCPSTAT_INC(tcps_rcvacktoomuch); 2511 goto dropafterack; 2512 } 2513 if (tcp_is_sack_recovery(tp, &to)) { 2514 if (((sack_changed = tcp_sack_doack(tp, &to, th->th_ack)) != 0) && 2515 (tp->t_flags & TF_LRD)) { 2516 tcp_sack_lost_retransmission(tp, th); 2517 } 2518 } else 2519 /* 2520 * Reset the value so that previous (valid) value 2521 * from the last ack with SACK doesn't get used. 2522 */ 2523 tp->sackhint.sacked_bytes = 0; 2524 2525 #ifdef TCP_HHOOK 2526 /* Run HHOOK_TCP_ESTABLISHED_IN helper hooks. */ 2527 hhook_run_tcp_est_in(tp, th, &to); 2528 #endif 2529 2530 if (SEQ_LEQ(th->th_ack, tp->snd_una)) { 2531 maxseg = tcp_maxseg(tp); 2532 if (tlen == 0 && 2533 (tiwin == tp->snd_wnd || 2534 (tp->t_flags & TF_SACK_PERMIT))) { 2535 /* 2536 * If this is the first time we've seen a 2537 * FIN from the remote, this is not a 2538 * duplicate and it needs to be processed 2539 * normally. This happens during a 2540 * simultaneous close. 2541 */ 2542 if ((thflags & TH_FIN) && 2543 (TCPS_HAVERCVDFIN(tp->t_state) == 0)) { 2544 tp->t_dupacks = 0; 2545 break; 2546 } 2547 TCPSTAT_INC(tcps_rcvdupack); 2548 /* 2549 * If we have outstanding data (other than 2550 * a window probe), this is a completely 2551 * duplicate ack (ie, window info didn't 2552 * change and FIN isn't set), 2553 * the ack is the biggest we've 2554 * seen and we've seen exactly our rexmt 2555 * threshold of them, assume a packet 2556 * has been dropped and retransmit it. 2557 * Kludge snd_nxt & the congestion 2558 * window so we send only this one 2559 * packet. 2560 * 2561 * We know we're losing at the current 2562 * window size so do congestion avoidance 2563 * (set ssthresh to half the current window 2564 * and pull our congestion window back to 2565 * the new ssthresh). 2566 * 2567 * Dup acks mean that packets have left the 2568 * network (they're now cached at the receiver) 2569 * so bump cwnd by the amount in the receiver 2570 * to keep a constant cwnd packets in the 2571 * network. 2572 * 2573 * When using TCP ECN, notify the peer that 2574 * we reduced the cwnd. 2575 */ 2576 /* 2577 * Following 2 kinds of acks should not affect 2578 * dupack counting: 2579 * 1) Old acks 2580 * 2) Acks with SACK but without any new SACK 2581 * information in them. These could result from 2582 * any anomaly in the network like a switch 2583 * duplicating packets or a possible DoS attack. 2584 */ 2585 if (th->th_ack != tp->snd_una || 2586 (tcp_is_sack_recovery(tp, &to) && 2587 !sack_changed)) 2588 break; 2589 else if (!tcp_timer_active(tp, TT_REXMT)) 2590 tp->t_dupacks = 0; 2591 else if (++tp->t_dupacks > tcprexmtthresh || 2592 IN_FASTRECOVERY(tp->t_flags)) { 2593 cc_ack_received(tp, th, nsegs, 2594 CC_DUPACK); 2595 if (V_tcp_do_prr && 2596 IN_FASTRECOVERY(tp->t_flags)) { 2597 tcp_do_prr_ack(tp, th, &to); 2598 } else if (tcp_is_sack_recovery(tp, &to) && 2599 IN_FASTRECOVERY(tp->t_flags)) { 2600 int awnd; 2601 2602 /* 2603 * Compute the amount of data in flight first. 2604 * We can inject new data into the pipe iff 2605 * we have less than 1/2 the original window's 2606 * worth of data in flight. 2607 */ 2608 if (V_tcp_do_newsack) 2609 awnd = tcp_compute_pipe(tp); 2610 else 2611 awnd = (tp->snd_nxt - tp->snd_fack) + 2612 tp->sackhint.sack_bytes_rexmit; 2613 2614 if (awnd < tp->snd_ssthresh) { 2615 tp->snd_cwnd += maxseg; 2616 if (tp->snd_cwnd > tp->snd_ssthresh) 2617 tp->snd_cwnd = tp->snd_ssthresh; 2618 } 2619 } else 2620 tp->snd_cwnd += maxseg; 2621 (void) tcp_output(tp); 2622 goto drop; 2623 } else if (tp->t_dupacks == tcprexmtthresh || 2624 (tp->t_flags & TF_SACK_PERMIT && 2625 V_tcp_do_newsack && 2626 tp->sackhint.sacked_bytes > 2627 (tcprexmtthresh - 1) * maxseg)) { 2628 enter_recovery: 2629 /* 2630 * Above is the RFC6675 trigger condition of 2631 * more than (dupthresh-1)*maxseg sacked data. 2632 * If the count of holes in the 2633 * scoreboard is >= dupthresh, we could 2634 * also enter loss recovery, but don't 2635 * have that value readily available. 2636 */ 2637 tp->t_dupacks = tcprexmtthresh; 2638 tcp_seq onxt = tp->snd_nxt; 2639 2640 /* 2641 * If we're doing sack, or prr, check 2642 * to see if we're already in sack 2643 * recovery. If we're not doing sack, 2644 * check to see if we're in newreno 2645 * recovery. 2646 */ 2647 if (V_tcp_do_prr || 2648 (tp->t_flags & TF_SACK_PERMIT)) { 2649 if (IN_FASTRECOVERY(tp->t_flags)) { 2650 tp->t_dupacks = 0; 2651 break; 2652 } 2653 } else { 2654 if (SEQ_LEQ(th->th_ack, 2655 tp->snd_recover)) { 2656 tp->t_dupacks = 0; 2657 break; 2658 } 2659 } 2660 /* Congestion signal before ack. */ 2661 cc_cong_signal(tp, th, CC_NDUPACK); 2662 cc_ack_received(tp, th, nsegs, 2663 CC_DUPACK); 2664 tcp_timer_activate(tp, TT_REXMT, 0); 2665 tp->t_rtttime = 0; 2666 if (V_tcp_do_prr) { 2667 /* 2668 * snd_ssthresh is already updated by 2669 * cc_cong_signal. 2670 */ 2671 if (tcp_is_sack_recovery(tp, &to)) { 2672 tp->sackhint.prr_delivered = 2673 tp->sackhint.sacked_bytes; 2674 } else { 2675 tp->sackhint.prr_delivered = 2676 imin(tp->snd_max - tp->snd_una, 2677 imin(INT_MAX / 65536, 2678 tp->t_dupacks) * maxseg); 2679 } 2680 tp->sackhint.recover_fs = max(1, 2681 tp->snd_nxt - tp->snd_una); 2682 } 2683 if (tcp_is_sack_recovery(tp, &to)) { 2684 TCPSTAT_INC( 2685 tcps_sack_recovery_episode); 2686 tp->snd_recover = tp->snd_nxt; 2687 tp->snd_cwnd = maxseg; 2688 (void) tcp_output(tp); 2689 if (SEQ_GT(th->th_ack, tp->snd_una)) 2690 goto resume_partialack; 2691 goto drop; 2692 } 2693 tp->snd_nxt = th->th_ack; 2694 tp->snd_cwnd = maxseg; 2695 (void) tcp_output(tp); 2696 KASSERT(tp->snd_limited <= 2, 2697 ("%s: tp->snd_limited too big", 2698 __func__)); 2699 tp->snd_cwnd = tp->snd_ssthresh + 2700 maxseg * 2701 (tp->t_dupacks - tp->snd_limited); 2702 if (SEQ_GT(onxt, tp->snd_nxt)) 2703 tp->snd_nxt = onxt; 2704 goto drop; 2705 } else if (V_tcp_do_rfc3042) { 2706 /* 2707 * Process first and second duplicate 2708 * ACKs. Each indicates a segment 2709 * leaving the network, creating room 2710 * for more. Make sure we can send a 2711 * packet on reception of each duplicate 2712 * ACK by increasing snd_cwnd by one 2713 * segment. Restore the original 2714 * snd_cwnd after packet transmission. 2715 */ 2716 cc_ack_received(tp, th, nsegs, 2717 CC_DUPACK); 2718 uint32_t oldcwnd = tp->snd_cwnd; 2719 tcp_seq oldsndmax = tp->snd_max; 2720 u_int sent; 2721 int avail; 2722 2723 KASSERT(tp->t_dupacks == 1 || 2724 tp->t_dupacks == 2, 2725 ("%s: dupacks not 1 or 2", 2726 __func__)); 2727 if (tp->t_dupacks == 1) 2728 tp->snd_limited = 0; 2729 tp->snd_cwnd = 2730 (tp->snd_nxt - tp->snd_una) + 2731 (tp->t_dupacks - tp->snd_limited) * 2732 maxseg; 2733 /* 2734 * Only call tcp_output when there 2735 * is new data available to be sent 2736 * or we need to send an ACK. 2737 */ 2738 SOCKBUF_LOCK(&so->so_snd); 2739 avail = sbavail(&so->so_snd) - 2740 (tp->snd_nxt - tp->snd_una); 2741 SOCKBUF_UNLOCK(&so->so_snd); 2742 if (avail > 0 || tp->t_flags & TF_ACKNOW) 2743 (void) tcp_output(tp); 2744 sent = tp->snd_max - oldsndmax; 2745 if (sent > maxseg) { 2746 KASSERT((tp->t_dupacks == 2 && 2747 tp->snd_limited == 0) || 2748 (sent == maxseg + 1 && 2749 tp->t_flags & TF_SENTFIN), 2750 ("%s: sent too much", 2751 __func__)); 2752 tp->snd_limited = 2; 2753 } else if (sent > 0) 2754 ++tp->snd_limited; 2755 tp->snd_cwnd = oldcwnd; 2756 goto drop; 2757 } 2758 } 2759 break; 2760 } else { 2761 /* 2762 * This ack is advancing the left edge, reset the 2763 * counter. 2764 */ 2765 tp->t_dupacks = 0; 2766 /* 2767 * If this ack also has new SACK info, increment the 2768 * counter as per rfc6675. The variable 2769 * sack_changed tracks all changes to the SACK 2770 * scoreboard, including when partial ACKs without 2771 * SACK options are received, and clear the scoreboard 2772 * from the left side. Such partial ACKs should not be 2773 * counted as dupacks here. 2774 */ 2775 if (tcp_is_sack_recovery(tp, &to) && 2776 sack_changed) { 2777 tp->t_dupacks++; 2778 /* limit overhead by setting maxseg last */ 2779 if (!IN_FASTRECOVERY(tp->t_flags) && 2780 (tp->sackhint.sacked_bytes > 2781 ((tcprexmtthresh - 1) * 2782 (maxseg = tcp_maxseg(tp))))) { 2783 goto enter_recovery; 2784 } 2785 } 2786 } 2787 2788 resume_partialack: 2789 KASSERT(SEQ_GT(th->th_ack, tp->snd_una), 2790 ("%s: th_ack <= snd_una", __func__)); 2791 2792 /* 2793 * If the congestion window was inflated to account 2794 * for the other side's cached packets, retract it. 2795 */ 2796 if (IN_FASTRECOVERY(tp->t_flags)) { 2797 if (SEQ_LT(th->th_ack, tp->snd_recover)) { 2798 if (tp->t_flags & TF_SACK_PERMIT) 2799 if (V_tcp_do_prr && to.to_flags & TOF_SACK) { 2800 tcp_timer_activate(tp, TT_REXMT, 0); 2801 tp->t_rtttime = 0; 2802 tcp_do_prr_ack(tp, th, &to); 2803 tp->t_flags |= TF_ACKNOW; 2804 (void) tcp_output(tp); 2805 } else 2806 tcp_sack_partialack(tp, th); 2807 else 2808 tcp_newreno_partial_ack(tp, th); 2809 } else 2810 cc_post_recovery(tp, th); 2811 } else if (IN_CONGRECOVERY(tp->t_flags)) { 2812 if (SEQ_LT(th->th_ack, tp->snd_recover)) { 2813 if (V_tcp_do_prr) { 2814 tp->sackhint.delivered_data = BYTES_THIS_ACK(tp, th); 2815 tp->snd_fack = th->th_ack; 2816 tcp_do_prr_ack(tp, th, &to); 2817 (void) tcp_output(tp); 2818 } 2819 } else 2820 cc_post_recovery(tp, th); 2821 } 2822 /* 2823 * If we reach this point, ACK is not a duplicate, 2824 * i.e., it ACKs something we sent. 2825 */ 2826 if (tp->t_flags & TF_NEEDSYN) { 2827 /* 2828 * T/TCP: Connection was half-synchronized, and our 2829 * SYN has been ACK'd (so connection is now fully 2830 * synchronized). Go to non-starred state, 2831 * increment snd_una for ACK of SYN, and check if 2832 * we can do window scaling. 2833 */ 2834 tp->t_flags &= ~TF_NEEDSYN; 2835 tp->snd_una++; 2836 /* Do window scaling? */ 2837 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2838 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2839 tp->rcv_scale = tp->request_r_scale; 2840 /* Send window already scaled. */ 2841 } 2842 } 2843 2844 process_ACK: 2845 INP_WLOCK_ASSERT(inp); 2846 2847 /* 2848 * Adjust for the SYN bit in sequence space, 2849 * but don't account for it in cwnd calculations. 2850 * This is for the SYN_RECEIVED, non-simultaneous 2851 * SYN case. SYN_SENT and simultaneous SYN are 2852 * treated elsewhere. 2853 */ 2854 if (incforsyn) 2855 tp->snd_una++; 2856 acked = BYTES_THIS_ACK(tp, th); 2857 KASSERT(acked >= 0, ("%s: acked unexepectedly negative " 2858 "(tp->snd_una=%u, th->th_ack=%u, tp=%p, m=%p)", __func__, 2859 tp->snd_una, th->th_ack, tp, m)); 2860 TCPSTAT_ADD(tcps_rcvackpack, nsegs); 2861 TCPSTAT_ADD(tcps_rcvackbyte, acked); 2862 2863 /* 2864 * If we just performed our first retransmit, and the ACK 2865 * arrives within our recovery window, then it was a mistake 2866 * to do the retransmit in the first place. Recover our 2867 * original cwnd and ssthresh, and proceed to transmit where 2868 * we left off. 2869 */ 2870 if (tp->t_rxtshift == 1 && 2871 tp->t_flags & TF_PREVVALID && 2872 tp->t_badrxtwin != 0 && 2873 to.to_flags & TOF_TS && 2874 to.to_tsecr != 0 && 2875 TSTMP_LT(to.to_tsecr, tp->t_badrxtwin)) 2876 cc_cong_signal(tp, th, CC_RTO_ERR); 2877 2878 /* 2879 * If we have a timestamp reply, update smoothed 2880 * round trip time. If no timestamp is present but 2881 * transmit timer is running and timed sequence 2882 * number was acked, update smoothed round trip time. 2883 * Since we now have an rtt measurement, cancel the 2884 * timer backoff (cf., Phil Karn's retransmit alg.). 2885 * Recompute the initial retransmit timer. 2886 * 2887 * Some boxes send broken timestamp replies 2888 * during the SYN+ACK phase, ignore 2889 * timestamps of 0 or we could calculate a 2890 * huge RTT and blow up the retransmit timer. 2891 */ 2892 if ((to.to_flags & TOF_TS) != 0 && to.to_tsecr) { 2893 uint32_t t; 2894 2895 t = tcp_ts_getticks() - to.to_tsecr; 2896 if (!tp->t_rttlow || tp->t_rttlow > t) 2897 tp->t_rttlow = t; 2898 tcp_xmit_timer(tp, TCP_TS_TO_TICKS(t) + 1); 2899 } else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) { 2900 if (!tp->t_rttlow || tp->t_rttlow > ticks - tp->t_rtttime) 2901 tp->t_rttlow = ticks - tp->t_rtttime; 2902 tcp_xmit_timer(tp, ticks - tp->t_rtttime); 2903 } 2904 2905 SOCKBUF_LOCK(&so->so_snd); 2906 /* 2907 * Clear t_acktime if remote side has ACKd all data in the 2908 * socket buffer and FIN (if applicable). 2909 * Otherwise, update t_acktime if we received a sufficiently 2910 * large ACK. 2911 */ 2912 if ((tp->t_state <= TCPS_CLOSE_WAIT && 2913 acked == sbavail(&so->so_snd)) || 2914 acked > sbavail(&so->so_snd)) 2915 tp->t_acktime = 0; 2916 else if (acked > 1) 2917 tp->t_acktime = ticks; 2918 2919 /* 2920 * If all outstanding data is acked, stop retransmit 2921 * timer and remember to restart (more output or persist). 2922 * If there is more data to be acked, restart retransmit 2923 * timer, using current (possibly backed-off) value. 2924 */ 2925 if (th->th_ack == tp->snd_max) { 2926 tcp_timer_activate(tp, TT_REXMT, 0); 2927 needoutput = 1; 2928 } else if (!tcp_timer_active(tp, TT_PERSIST)) 2929 tcp_timer_activate(tp, TT_REXMT, TP_RXTCUR(tp)); 2930 2931 /* 2932 * If no data (only SYN) was ACK'd, 2933 * skip rest of ACK processing. 2934 */ 2935 if (acked == 0) { 2936 SOCKBUF_UNLOCK(&so->so_snd); 2937 goto step6; 2938 } 2939 2940 /* 2941 * Let the congestion control algorithm update congestion 2942 * control related information. This typically means increasing 2943 * the congestion window. 2944 */ 2945 cc_ack_received(tp, th, nsegs, CC_ACK); 2946 2947 if (acked > sbavail(&so->so_snd)) { 2948 if (tp->snd_wnd >= sbavail(&so->so_snd)) 2949 tp->snd_wnd -= sbavail(&so->so_snd); 2950 else 2951 tp->snd_wnd = 0; 2952 mfree = sbcut_locked(&so->so_snd, 2953 (int)sbavail(&so->so_snd)); 2954 ourfinisacked = 1; 2955 } else { 2956 mfree = sbcut_locked(&so->so_snd, acked); 2957 if (tp->snd_wnd >= (uint32_t) acked) 2958 tp->snd_wnd -= acked; 2959 else 2960 tp->snd_wnd = 0; 2961 ourfinisacked = 0; 2962 } 2963 /* NB: sowwakeup_locked() does an implicit unlock. */ 2964 sowwakeup_locked(so); 2965 m_freem(mfree); 2966 /* Detect una wraparound. */ 2967 if (!IN_RECOVERY(tp->t_flags) && 2968 SEQ_GT(tp->snd_una, tp->snd_recover) && 2969 SEQ_LEQ(th->th_ack, tp->snd_recover)) 2970 tp->snd_recover = th->th_ack - 1; 2971 /* XXXLAS: Can this be moved up into cc_post_recovery? */ 2972 if (IN_RECOVERY(tp->t_flags) && 2973 SEQ_GEQ(th->th_ack, tp->snd_recover)) { 2974 EXIT_RECOVERY(tp->t_flags); 2975 } 2976 tp->snd_una = th->th_ack; 2977 if (tp->t_flags & TF_SACK_PERMIT) { 2978 if (SEQ_GT(tp->snd_una, tp->snd_recover)) 2979 tp->snd_recover = tp->snd_una; 2980 } 2981 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2982 tp->snd_nxt = tp->snd_una; 2983 2984 switch (tp->t_state) { 2985 /* 2986 * In FIN_WAIT_1 STATE in addition to the processing 2987 * for the ESTABLISHED state if our FIN is now acknowledged 2988 * then enter FIN_WAIT_2. 2989 */ 2990 case TCPS_FIN_WAIT_1: 2991 if (ourfinisacked) { 2992 /* 2993 * If we can't receive any more 2994 * data, then closing user can proceed. 2995 * Starting the timer is contrary to the 2996 * specification, but if we don't get a FIN 2997 * we'll hang forever. 2998 */ 2999 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 3000 soisdisconnected(so); 3001 tcp_timer_activate(tp, TT_2MSL, 3002 (tcp_fast_finwait2_recycle ? 3003 tcp_finwait2_timeout : 3004 TP_MAXIDLE(tp))); 3005 } 3006 tcp_state_change(tp, TCPS_FIN_WAIT_2); 3007 } 3008 break; 3009 3010 /* 3011 * In CLOSING STATE in addition to the processing for 3012 * the ESTABLISHED state if the ACK acknowledges our FIN 3013 * then enter the TIME-WAIT state, otherwise ignore 3014 * the segment. 3015 */ 3016 case TCPS_CLOSING: 3017 if (ourfinisacked) { 3018 tcp_twstart(tp); 3019 m_freem(m); 3020 return; 3021 } 3022 break; 3023 3024 /* 3025 * In LAST_ACK, we may still be waiting for data to drain 3026 * and/or to be acked, as well as for the ack of our FIN. 3027 * If our FIN is now acknowledged, delete the TCB, 3028 * enter the closed state and return. 3029 */ 3030 case TCPS_LAST_ACK: 3031 if (ourfinisacked) { 3032 tp = tcp_close(tp); 3033 goto drop; 3034 } 3035 break; 3036 } 3037 } 3038 3039 step6: 3040 INP_WLOCK_ASSERT(inp); 3041 3042 /* 3043 * Update window information. 3044 * Don't look at window if no ACK: TAC's send garbage on first SYN. 3045 */ 3046 if ((thflags & TH_ACK) && 3047 (SEQ_LT(tp->snd_wl1, th->th_seq) || 3048 (tp->snd_wl1 == th->th_seq && (SEQ_LT(tp->snd_wl2, th->th_ack) || 3049 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))) { 3050 /* keep track of pure window updates */ 3051 if (tlen == 0 && 3052 tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) 3053 TCPSTAT_INC(tcps_rcvwinupd); 3054 tp->snd_wnd = tiwin; 3055 tp->snd_wl1 = th->th_seq; 3056 tp->snd_wl2 = th->th_ack; 3057 if (tp->snd_wnd > tp->max_sndwnd) 3058 tp->max_sndwnd = tp->snd_wnd; 3059 needoutput = 1; 3060 } 3061 3062 /* 3063 * Process segments with URG. 3064 */ 3065 if ((thflags & TH_URG) && th->th_urp && 3066 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3067 /* 3068 * This is a kludge, but if we receive and accept 3069 * random urgent pointers, we'll crash in 3070 * soreceive. It's hard to imagine someone 3071 * actually wanting to send this much urgent data. 3072 */ 3073 SOCKBUF_LOCK(&so->so_rcv); 3074 if (th->th_urp + sbavail(&so->so_rcv) > sb_max) { 3075 th->th_urp = 0; /* XXX */ 3076 thflags &= ~TH_URG; /* XXX */ 3077 SOCKBUF_UNLOCK(&so->so_rcv); /* XXX */ 3078 goto dodata; /* XXX */ 3079 } 3080 /* 3081 * If this segment advances the known urgent pointer, 3082 * then mark the data stream. This should not happen 3083 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 3084 * a FIN has been received from the remote side. 3085 * In these states we ignore the URG. 3086 * 3087 * According to RFC961 (Assigned Protocols), 3088 * the urgent pointer points to the last octet 3089 * of urgent data. We continue, however, 3090 * to consider it to indicate the first octet 3091 * of data past the urgent section as the original 3092 * spec states (in one of two places). 3093 */ 3094 if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) { 3095 tp->rcv_up = th->th_seq + th->th_urp; 3096 so->so_oobmark = sbavail(&so->so_rcv) + 3097 (tp->rcv_up - tp->rcv_nxt) - 1; 3098 if (so->so_oobmark == 0) 3099 so->so_rcv.sb_state |= SBS_RCVATMARK; 3100 sohasoutofband(so); 3101 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); 3102 } 3103 SOCKBUF_UNLOCK(&so->so_rcv); 3104 /* 3105 * Remove out of band data so doesn't get presented to user. 3106 * This can happen independent of advancing the URG pointer, 3107 * but if two URG's are pending at once, some out-of-band 3108 * data may creep in... ick. 3109 */ 3110 if (th->th_urp <= (uint32_t)tlen && 3111 !(so->so_options & SO_OOBINLINE)) { 3112 /* hdr drop is delayed */ 3113 tcp_pulloutofband(so, th, m, drop_hdrlen); 3114 } 3115 } else { 3116 /* 3117 * If no out of band data is expected, 3118 * pull receive urgent pointer along 3119 * with the receive window. 3120 */ 3121 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) 3122 tp->rcv_up = tp->rcv_nxt; 3123 } 3124 dodata: /* XXX */ 3125 INP_WLOCK_ASSERT(inp); 3126 3127 /* 3128 * Process the segment text, merging it into the TCP sequencing queue, 3129 * and arranging for acknowledgment of receipt if necessary. 3130 * This process logically involves adjusting tp->rcv_wnd as data 3131 * is presented to the user (this happens in tcp_usrreq.c, 3132 * case PRU_RCVD). If a FIN has already been received on this 3133 * connection then we just ignore the text. 3134 */ 3135 tfo_syn = ((tp->t_state == TCPS_SYN_RECEIVED) && 3136 IS_FASTOPEN(tp->t_flags)); 3137 if ((tlen || (thflags & TH_FIN) || (tfo_syn && tlen > 0)) && 3138 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3139 tcp_seq save_start = th->th_seq; 3140 tcp_seq save_rnxt = tp->rcv_nxt; 3141 int save_tlen = tlen; 3142 m_adj(m, drop_hdrlen); /* delayed header drop */ 3143 /* 3144 * Insert segment which includes th into TCP reassembly queue 3145 * with control block tp. Set thflags to whether reassembly now 3146 * includes a segment with FIN. This handles the common case 3147 * inline (segment is the next to be received on an established 3148 * connection, and the queue is empty), avoiding linkage into 3149 * and removal from the queue and repetition of various 3150 * conversions. 3151 * Set DELACK for segments received in order, but ack 3152 * immediately when segments are out of order (so 3153 * fast retransmit can work). 3154 */ 3155 if (th->th_seq == tp->rcv_nxt && 3156 SEGQ_EMPTY(tp) && 3157 (TCPS_HAVEESTABLISHED(tp->t_state) || 3158 tfo_syn)) { 3159 if (DELAY_ACK(tp, tlen) || tfo_syn) 3160 tp->t_flags |= TF_DELACK; 3161 else 3162 tp->t_flags |= TF_ACKNOW; 3163 tp->rcv_nxt += tlen; 3164 if (tlen && 3165 ((tp->t_flags2 & TF2_FBYTES_COMPLETE) == 0) && 3166 (tp->t_fbyte_in == 0)) { 3167 tp->t_fbyte_in = ticks; 3168 if (tp->t_fbyte_in == 0) 3169 tp->t_fbyte_in = 1; 3170 if (tp->t_fbyte_out && tp->t_fbyte_in) 3171 tp->t_flags2 |= TF2_FBYTES_COMPLETE; 3172 } 3173 thflags = tcp_get_flags(th) & TH_FIN; 3174 TCPSTAT_INC(tcps_rcvpack); 3175 TCPSTAT_ADD(tcps_rcvbyte, tlen); 3176 SOCKBUF_LOCK(&so->so_rcv); 3177 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) 3178 m_freem(m); 3179 else 3180 sbappendstream_locked(&so->so_rcv, m, 0); 3181 tp->t_flags |= TF_WAKESOR; 3182 } else { 3183 /* 3184 * XXX: Due to the header drop above "th" is 3185 * theoretically invalid by now. Fortunately 3186 * m_adj() doesn't actually frees any mbufs 3187 * when trimming from the head. 3188 */ 3189 tcp_seq temp = save_start; 3190 3191 thflags = tcp_reass(tp, th, &temp, &tlen, m); 3192 tp->t_flags |= TF_ACKNOW; 3193 } 3194 if ((tp->t_flags & TF_SACK_PERMIT) && 3195 (save_tlen > 0) && 3196 TCPS_HAVEESTABLISHED(tp->t_state)) { 3197 if ((tlen == 0) && (SEQ_LT(save_start, save_rnxt))) { 3198 /* 3199 * DSACK actually handled in the fastpath 3200 * above. 3201 */ 3202 tcp_update_sack_list(tp, save_start, 3203 save_start + save_tlen); 3204 } else if ((tlen > 0) && SEQ_GT(tp->rcv_nxt, save_rnxt)) { 3205 if ((tp->rcv_numsacks >= 1) && 3206 (tp->sackblks[0].end == save_start)) { 3207 /* 3208 * Partial overlap, recorded at todrop 3209 * above. 3210 */ 3211 tcp_update_sack_list(tp, 3212 tp->sackblks[0].start, 3213 tp->sackblks[0].end); 3214 } else { 3215 tcp_update_dsack_list(tp, save_start, 3216 save_start + save_tlen); 3217 } 3218 } else if (tlen >= save_tlen) { 3219 /* Update of sackblks. */ 3220 tcp_update_dsack_list(tp, save_start, 3221 save_start + save_tlen); 3222 } else if (tlen > 0) { 3223 tcp_update_dsack_list(tp, save_start, 3224 save_start + tlen); 3225 } 3226 } 3227 tcp_handle_wakeup(tp); 3228 #if 0 3229 /* 3230 * Note the amount of data that peer has sent into 3231 * our window, in order to estimate the sender's 3232 * buffer size. 3233 * XXX: Unused. 3234 */ 3235 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt)) 3236 len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); 3237 else 3238 len = so->so_rcv.sb_hiwat; 3239 #endif 3240 } else { 3241 m_freem(m); 3242 thflags &= ~TH_FIN; 3243 } 3244 3245 /* 3246 * If FIN is received ACK the FIN and let the user know 3247 * that the connection is closing. 3248 */ 3249 if (thflags & TH_FIN) { 3250 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3251 /* The socket upcall is handled by socantrcvmore. */ 3252 socantrcvmore(so); 3253 /* 3254 * If connection is half-synchronized 3255 * (ie NEEDSYN flag on) then delay ACK, 3256 * so it may be piggybacked when SYN is sent. 3257 * Otherwise, since we received a FIN then no 3258 * more input can be expected, send ACK now. 3259 */ 3260 if (tp->t_flags & TF_NEEDSYN) 3261 tp->t_flags |= TF_DELACK; 3262 else 3263 tp->t_flags |= TF_ACKNOW; 3264 tp->rcv_nxt++; 3265 } 3266 switch (tp->t_state) { 3267 /* 3268 * In SYN_RECEIVED and ESTABLISHED STATES 3269 * enter the CLOSE_WAIT state. 3270 */ 3271 case TCPS_SYN_RECEIVED: 3272 tp->t_starttime = ticks; 3273 /* FALLTHROUGH */ 3274 case TCPS_ESTABLISHED: 3275 tcp_state_change(tp, TCPS_CLOSE_WAIT); 3276 break; 3277 3278 /* 3279 * If still in FIN_WAIT_1 STATE FIN has not been acked so 3280 * enter the CLOSING state. 3281 */ 3282 case TCPS_FIN_WAIT_1: 3283 tcp_state_change(tp, TCPS_CLOSING); 3284 break; 3285 3286 /* 3287 * In FIN_WAIT_2 state enter the TIME_WAIT state, 3288 * starting the time-wait timer, turning off the other 3289 * standard timers. 3290 */ 3291 case TCPS_FIN_WAIT_2: 3292 tcp_twstart(tp); 3293 return; 3294 } 3295 } 3296 TCP_PROBE3(debug__input, tp, th, m); 3297 3298 /* 3299 * Return any desired output. 3300 */ 3301 if (needoutput || (tp->t_flags & TF_ACKNOW)) 3302 (void) tcp_output(tp); 3303 3304 check_delack: 3305 INP_WLOCK_ASSERT(inp); 3306 3307 if (tp->t_flags & TF_DELACK) { 3308 tp->t_flags &= ~TF_DELACK; 3309 tcp_timer_activate(tp, TT_DELACK, tcp_delacktime); 3310 } 3311 INP_WUNLOCK(inp); 3312 return; 3313 3314 dropafterack: 3315 /* 3316 * Generate an ACK dropping incoming segment if it occupies 3317 * sequence space, where the ACK reflects our state. 3318 * 3319 * We can now skip the test for the RST flag since all 3320 * paths to this code happen after packets containing 3321 * RST have been dropped. 3322 * 3323 * In the SYN-RECEIVED state, don't send an ACK unless the 3324 * segment we received passes the SYN-RECEIVED ACK test. 3325 * If it fails send a RST. This breaks the loop in the 3326 * "LAND" DoS attack, and also prevents an ACK storm 3327 * between two listening ports that have been sent forged 3328 * SYN segments, each with the source address of the other. 3329 */ 3330 if (tp->t_state == TCPS_SYN_RECEIVED && (thflags & TH_ACK) && 3331 (SEQ_GT(tp->snd_una, th->th_ack) || 3332 SEQ_GT(th->th_ack, tp->snd_max)) ) { 3333 rstreason = BANDLIM_RST_OPENPORT; 3334 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 3335 goto dropwithreset; 3336 } 3337 TCP_PROBE3(debug__input, tp, th, m); 3338 tp->t_flags |= TF_ACKNOW; 3339 (void) tcp_output(tp); 3340 INP_WUNLOCK(inp); 3341 m_freem(m); 3342 return; 3343 3344 dropwithreset: 3345 if (tp != NULL) { 3346 tcp_dropwithreset(m, th, tp, tlen, rstreason); 3347 INP_WUNLOCK(inp); 3348 } else 3349 tcp_dropwithreset(m, th, NULL, tlen, rstreason); 3350 return; 3351 3352 drop: 3353 /* 3354 * Drop space held by incoming segment and return. 3355 */ 3356 TCP_PROBE3(debug__input, tp, th, m); 3357 if (tp != NULL) { 3358 INP_WUNLOCK(inp); 3359 } 3360 m_freem(m); 3361 } 3362 3363 /* 3364 * Issue RST and make ACK acceptable to originator of segment. 3365 * The mbuf must still include the original packet header. 3366 * tp may be NULL. 3367 */ 3368 void 3369 tcp_dropwithreset(struct mbuf *m, struct tcphdr *th, struct tcpcb *tp, 3370 int tlen, int rstreason) 3371 { 3372 #ifdef INET 3373 struct ip *ip; 3374 #endif 3375 #ifdef INET6 3376 struct ip6_hdr *ip6; 3377 #endif 3378 3379 if (tp != NULL) { 3380 INP_LOCK_ASSERT(tptoinpcb(tp)); 3381 } 3382 3383 /* Don't bother if destination was broadcast/multicast. */ 3384 if ((tcp_get_flags(th) & TH_RST) || m->m_flags & (M_BCAST|M_MCAST)) 3385 goto drop; 3386 #ifdef INET6 3387 if (mtod(m, struct ip *)->ip_v == 6) { 3388 ip6 = mtod(m, struct ip6_hdr *); 3389 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 3390 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) 3391 goto drop; 3392 /* IPv6 anycast check is done at tcp6_input() */ 3393 } 3394 #endif 3395 #if defined(INET) && defined(INET6) 3396 else 3397 #endif 3398 #ifdef INET 3399 { 3400 ip = mtod(m, struct ip *); 3401 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || 3402 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 3403 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || 3404 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 3405 goto drop; 3406 } 3407 #endif 3408 3409 /* Perform bandwidth limiting. */ 3410 if (badport_bandlim(rstreason) < 0) 3411 goto drop; 3412 3413 /* tcp_respond consumes the mbuf chain. */ 3414 if (tcp_get_flags(th) & TH_ACK) { 3415 tcp_respond(tp, mtod(m, void *), th, m, (tcp_seq)0, 3416 th->th_ack, TH_RST); 3417 } else { 3418 if (tcp_get_flags(th) & TH_SYN) 3419 tlen++; 3420 if (tcp_get_flags(th) & TH_FIN) 3421 tlen++; 3422 tcp_respond(tp, mtod(m, void *), th, m, th->th_seq+tlen, 3423 (tcp_seq)0, TH_RST|TH_ACK); 3424 } 3425 return; 3426 drop: 3427 m_freem(m); 3428 } 3429 3430 /* 3431 * Parse TCP options and place in tcpopt. 3432 */ 3433 void 3434 tcp_dooptions(struct tcpopt *to, u_char *cp, int cnt, int flags) 3435 { 3436 int opt, optlen; 3437 3438 to->to_flags = 0; 3439 for (; cnt > 0; cnt -= optlen, cp += optlen) { 3440 opt = cp[0]; 3441 if (opt == TCPOPT_EOL) 3442 break; 3443 if (opt == TCPOPT_NOP) 3444 optlen = 1; 3445 else { 3446 if (cnt < 2) 3447 break; 3448 optlen = cp[1]; 3449 if (optlen < 2 || optlen > cnt) 3450 break; 3451 } 3452 switch (opt) { 3453 case TCPOPT_MAXSEG: 3454 if (optlen != TCPOLEN_MAXSEG) 3455 continue; 3456 if (!(flags & TO_SYN)) 3457 continue; 3458 to->to_flags |= TOF_MSS; 3459 bcopy((char *)cp + 2, 3460 (char *)&to->to_mss, sizeof(to->to_mss)); 3461 to->to_mss = ntohs(to->to_mss); 3462 break; 3463 case TCPOPT_WINDOW: 3464 if (optlen != TCPOLEN_WINDOW) 3465 continue; 3466 if (!(flags & TO_SYN)) 3467 continue; 3468 to->to_flags |= TOF_SCALE; 3469 to->to_wscale = min(cp[2], TCP_MAX_WINSHIFT); 3470 break; 3471 case TCPOPT_TIMESTAMP: 3472 if (optlen != TCPOLEN_TIMESTAMP) 3473 continue; 3474 to->to_flags |= TOF_TS; 3475 bcopy((char *)cp + 2, 3476 (char *)&to->to_tsval, sizeof(to->to_tsval)); 3477 to->to_tsval = ntohl(to->to_tsval); 3478 bcopy((char *)cp + 6, 3479 (char *)&to->to_tsecr, sizeof(to->to_tsecr)); 3480 to->to_tsecr = ntohl(to->to_tsecr); 3481 break; 3482 case TCPOPT_SIGNATURE: 3483 /* 3484 * In order to reply to a host which has set the 3485 * TCP_SIGNATURE option in its initial SYN, we have 3486 * to record the fact that the option was observed 3487 * here for the syncache code to perform the correct 3488 * response. 3489 */ 3490 if (optlen != TCPOLEN_SIGNATURE) 3491 continue; 3492 to->to_flags |= TOF_SIGNATURE; 3493 to->to_signature = cp + 2; 3494 break; 3495 case TCPOPT_SACK_PERMITTED: 3496 if (optlen != TCPOLEN_SACK_PERMITTED) 3497 continue; 3498 if (!(flags & TO_SYN)) 3499 continue; 3500 if (!V_tcp_do_sack) 3501 continue; 3502 to->to_flags |= TOF_SACKPERM; 3503 break; 3504 case TCPOPT_SACK: 3505 if (optlen <= 2 || (optlen - 2) % TCPOLEN_SACK != 0) 3506 continue; 3507 if (flags & TO_SYN) 3508 continue; 3509 to->to_flags |= TOF_SACK; 3510 to->to_nsacks = (optlen - 2) / TCPOLEN_SACK; 3511 to->to_sacks = cp + 2; 3512 TCPSTAT_INC(tcps_sack_rcv_blocks); 3513 break; 3514 case TCPOPT_FAST_OPEN: 3515 /* 3516 * Cookie length validation is performed by the 3517 * server side cookie checking code or the client 3518 * side cookie cache update code. 3519 */ 3520 if (!(flags & TO_SYN)) 3521 continue; 3522 if (!V_tcp_fastopen_client_enable && 3523 !V_tcp_fastopen_server_enable) 3524 continue; 3525 to->to_flags |= TOF_FASTOPEN; 3526 to->to_tfo_len = optlen - 2; 3527 to->to_tfo_cookie = to->to_tfo_len ? cp + 2 : NULL; 3528 break; 3529 default: 3530 continue; 3531 } 3532 } 3533 } 3534 3535 /* 3536 * Pull out of band byte out of a segment so 3537 * it doesn't appear in the user's data queue. 3538 * It is still reflected in the segment length for 3539 * sequencing purposes. 3540 */ 3541 void 3542 tcp_pulloutofband(struct socket *so, struct tcphdr *th, struct mbuf *m, 3543 int off) 3544 { 3545 int cnt = off + th->th_urp - 1; 3546 3547 while (cnt >= 0) { 3548 if (m->m_len > cnt) { 3549 char *cp = mtod(m, caddr_t) + cnt; 3550 struct tcpcb *tp = sototcpcb(so); 3551 3552 INP_WLOCK_ASSERT(tptoinpcb(tp)); 3553 3554 tp->t_iobc = *cp; 3555 tp->t_oobflags |= TCPOOB_HAVEDATA; 3556 bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); 3557 m->m_len--; 3558 if (m->m_flags & M_PKTHDR) 3559 m->m_pkthdr.len--; 3560 return; 3561 } 3562 cnt -= m->m_len; 3563 m = m->m_next; 3564 if (m == NULL) 3565 break; 3566 } 3567 panic("tcp_pulloutofband"); 3568 } 3569 3570 /* 3571 * Collect new round-trip time estimate 3572 * and update averages and current timeout. 3573 */ 3574 void 3575 tcp_xmit_timer(struct tcpcb *tp, int rtt) 3576 { 3577 int delta; 3578 3579 INP_WLOCK_ASSERT(tptoinpcb(tp)); 3580 3581 TCPSTAT_INC(tcps_rttupdated); 3582 if (tp->t_rttupdated < UCHAR_MAX) 3583 tp->t_rttupdated++; 3584 #ifdef STATS 3585 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_RTT, 3586 imax(0, rtt * 1000 / hz)); 3587 #endif 3588 if ((tp->t_srtt != 0) && (tp->t_rxtshift <= TCP_RTT_INVALIDATE)) { 3589 /* 3590 * srtt is stored as fixed point with 5 bits after the 3591 * binary point (i.e., scaled by 8). The following magic 3592 * is equivalent to the smoothing algorithm in rfc793 with 3593 * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed 3594 * point). Adjust rtt to origin 0. 3595 */ 3596 delta = ((rtt - 1) << TCP_DELTA_SHIFT) 3597 - (tp->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT)); 3598 3599 if ((tp->t_srtt += delta) <= 0) 3600 tp->t_srtt = 1; 3601 3602 /* 3603 * We accumulate a smoothed rtt variance (actually, a 3604 * smoothed mean difference), then set the retransmit 3605 * timer to smoothed rtt + 4 times the smoothed variance. 3606 * rttvar is stored as fixed point with 4 bits after the 3607 * binary point (scaled by 16). The following is 3608 * equivalent to rfc793 smoothing with an alpha of .75 3609 * (rttvar = rttvar*3/4 + |delta| / 4). This replaces 3610 * rfc793's wired-in beta. 3611 */ 3612 if (delta < 0) 3613 delta = -delta; 3614 delta -= tp->t_rttvar >> (TCP_RTTVAR_SHIFT - TCP_DELTA_SHIFT); 3615 if ((tp->t_rttvar += delta) <= 0) 3616 tp->t_rttvar = 1; 3617 } else { 3618 /* 3619 * No rtt measurement yet - use the unsmoothed rtt. 3620 * Set the variance to half the rtt (so our first 3621 * retransmit happens at 3*rtt). 3622 */ 3623 tp->t_srtt = rtt << TCP_RTT_SHIFT; 3624 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1); 3625 } 3626 tp->t_rtttime = 0; 3627 tp->t_rxtshift = 0; 3628 3629 /* 3630 * the retransmit should happen at rtt + 4 * rttvar. 3631 * Because of the way we do the smoothing, srtt and rttvar 3632 * will each average +1/2 tick of bias. When we compute 3633 * the retransmit timer, we want 1/2 tick of rounding and 3634 * 1 extra tick because of +-1/2 tick uncertainty in the 3635 * firing of the timer. The bias will give us exactly the 3636 * 1.5 tick we need. But, because the bias is 3637 * statistical, we have to test that we don't drop below 3638 * the minimum feasible timer (which is 2 ticks). 3639 */ 3640 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), 3641 max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX); 3642 3643 /* 3644 * We received an ack for a packet that wasn't retransmitted; 3645 * it is probably safe to discard any error indications we've 3646 * received recently. This isn't quite right, but close enough 3647 * for now (a route might have failed after we sent a segment, 3648 * and the return path might not be symmetrical). 3649 */ 3650 tp->t_softerror = 0; 3651 } 3652 3653 /* 3654 * Determine a reasonable value for maxseg size. 3655 * If the route is known, check route for mtu. 3656 * If none, use an mss that can be handled on the outgoing interface 3657 * without forcing IP to fragment. If no route is found, route has no mtu, 3658 * or the destination isn't local, use a default, hopefully conservative 3659 * size (usually 512 or the default IP max size, but no more than the mtu 3660 * of the interface), as we can't discover anything about intervening 3661 * gateways or networks. We also initialize the congestion/slow start 3662 * window to be a single segment if the destination isn't local. 3663 * While looking at the routing entry, we also initialize other path-dependent 3664 * parameters from pre-set or cached values in the routing entry. 3665 * 3666 * NOTE that resulting t_maxseg doesn't include space for TCP options or 3667 * IP options, e.g. IPSEC data, since length of this data may vary, and 3668 * thus it is calculated for every segment separately in tcp_output(). 3669 * 3670 * NOTE that this routine is only called when we process an incoming 3671 * segment, or an ICMP need fragmentation datagram. Outgoing SYN/ACK MSS 3672 * settings are handled in tcp_mssopt(). 3673 */ 3674 void 3675 tcp_mss_update(struct tcpcb *tp, int offer, int mtuoffer, 3676 struct hc_metrics_lite *metricptr, struct tcp_ifcap *cap) 3677 { 3678 int mss = 0; 3679 uint32_t maxmtu = 0; 3680 struct inpcb *inp = tptoinpcb(tp); 3681 struct hc_metrics_lite metrics; 3682 #ifdef INET6 3683 int isipv6 = ((inp->inp_vflag & INP_IPV6) != 0) ? 1 : 0; 3684 size_t min_protoh = isipv6 ? 3685 sizeof (struct ip6_hdr) + sizeof (struct tcphdr) : 3686 sizeof (struct tcpiphdr); 3687 #else 3688 size_t min_protoh = sizeof(struct tcpiphdr); 3689 #endif 3690 3691 INP_WLOCK_ASSERT(inp); 3692 3693 if (tp->t_port) 3694 min_protoh += V_tcp_udp_tunneling_overhead; 3695 if (mtuoffer != -1) { 3696 KASSERT(offer == -1, ("%s: conflict", __func__)); 3697 offer = mtuoffer - min_protoh; 3698 } 3699 3700 /* Initialize. */ 3701 #ifdef INET6 3702 if (isipv6) { 3703 maxmtu = tcp_maxmtu6(&inp->inp_inc, cap); 3704 tp->t_maxseg = V_tcp_v6mssdflt; 3705 } 3706 #endif 3707 #if defined(INET) && defined(INET6) 3708 else 3709 #endif 3710 #ifdef INET 3711 { 3712 maxmtu = tcp_maxmtu(&inp->inp_inc, cap); 3713 tp->t_maxseg = V_tcp_mssdflt; 3714 } 3715 #endif 3716 3717 /* 3718 * No route to sender, stay with default mss and return. 3719 */ 3720 if (maxmtu == 0) { 3721 /* 3722 * In case we return early we need to initialize metrics 3723 * to a defined state as tcp_hc_get() would do for us 3724 * if there was no cache hit. 3725 */ 3726 if (metricptr != NULL) 3727 bzero(metricptr, sizeof(struct hc_metrics_lite)); 3728 return; 3729 } 3730 3731 /* What have we got? */ 3732 switch (offer) { 3733 case 0: 3734 /* 3735 * Offer == 0 means that there was no MSS on the SYN 3736 * segment, in this case we use tcp_mssdflt as 3737 * already assigned to t_maxseg above. 3738 */ 3739 offer = tp->t_maxseg; 3740 break; 3741 3742 case -1: 3743 /* 3744 * Offer == -1 means that we didn't receive SYN yet. 3745 */ 3746 /* FALLTHROUGH */ 3747 3748 default: 3749 /* 3750 * Prevent DoS attack with too small MSS. Round up 3751 * to at least minmss. 3752 */ 3753 offer = max(offer, V_tcp_minmss); 3754 } 3755 3756 /* 3757 * rmx information is now retrieved from tcp_hostcache. 3758 */ 3759 tcp_hc_get(&inp->inp_inc, &metrics); 3760 if (metricptr != NULL) 3761 bcopy(&metrics, metricptr, sizeof(struct hc_metrics_lite)); 3762 3763 /* 3764 * If there's a discovered mtu in tcp hostcache, use it. 3765 * Else, use the link mtu. 3766 */ 3767 if (metrics.rmx_mtu) 3768 mss = min(metrics.rmx_mtu, maxmtu) - min_protoh; 3769 else { 3770 #ifdef INET6 3771 if (isipv6) { 3772 mss = maxmtu - min_protoh; 3773 if (!V_path_mtu_discovery && 3774 !in6_localaddr(&inp->in6p_faddr)) 3775 mss = min(mss, V_tcp_v6mssdflt); 3776 } 3777 #endif 3778 #if defined(INET) && defined(INET6) 3779 else 3780 #endif 3781 #ifdef INET 3782 { 3783 mss = maxmtu - min_protoh; 3784 if (!V_path_mtu_discovery && 3785 !in_localaddr(inp->inp_faddr)) 3786 mss = min(mss, V_tcp_mssdflt); 3787 } 3788 #endif 3789 /* 3790 * XXX - The above conditional (mss = maxmtu - min_protoh) 3791 * probably violates the TCP spec. 3792 * The problem is that, since we don't know the 3793 * other end's MSS, we are supposed to use a conservative 3794 * default. But, if we do that, then MTU discovery will 3795 * never actually take place, because the conservative 3796 * default is much less than the MTUs typically seen 3797 * on the Internet today. For the moment, we'll sweep 3798 * this under the carpet. 3799 * 3800 * The conservative default might not actually be a problem 3801 * if the only case this occurs is when sending an initial 3802 * SYN with options and data to a host we've never talked 3803 * to before. Then, they will reply with an MSS value which 3804 * will get recorded and the new parameters should get 3805 * recomputed. For Further Study. 3806 */ 3807 } 3808 mss = min(mss, offer); 3809 3810 /* 3811 * Sanity check: make sure that maxseg will be large 3812 * enough to allow some data on segments even if the 3813 * all the option space is used (40bytes). Otherwise 3814 * funny things may happen in tcp_output. 3815 * 3816 * XXXGL: shouldn't we reserve space for IP/IPv6 options? 3817 */ 3818 mss = max(mss, 64); 3819 3820 tp->t_maxseg = mss; 3821 } 3822 3823 void 3824 tcp_mss(struct tcpcb *tp, int offer) 3825 { 3826 int mss; 3827 uint32_t bufsize; 3828 struct inpcb *inp = tptoinpcb(tp); 3829 struct socket *so; 3830 struct hc_metrics_lite metrics; 3831 struct tcp_ifcap cap; 3832 3833 KASSERT(tp != NULL, ("%s: tp == NULL", __func__)); 3834 3835 bzero(&cap, sizeof(cap)); 3836 tcp_mss_update(tp, offer, -1, &metrics, &cap); 3837 3838 mss = tp->t_maxseg; 3839 3840 /* 3841 * If there's a pipesize, change the socket buffer to that size, 3842 * don't change if sb_hiwat is different than default (then it 3843 * has been changed on purpose with setsockopt). 3844 * Make the socket buffers an integral number of mss units; 3845 * if the mss is larger than the socket buffer, decrease the mss. 3846 */ 3847 so = inp->inp_socket; 3848 SOCKBUF_LOCK(&so->so_snd); 3849 if ((so->so_snd.sb_hiwat == V_tcp_sendspace) && metrics.rmx_sendpipe) 3850 bufsize = metrics.rmx_sendpipe; 3851 else 3852 bufsize = so->so_snd.sb_hiwat; 3853 if (bufsize < mss) 3854 mss = bufsize; 3855 else { 3856 bufsize = roundup(bufsize, mss); 3857 if (bufsize > sb_max) 3858 bufsize = sb_max; 3859 if (bufsize > so->so_snd.sb_hiwat) 3860 (void)sbreserve_locked(so, SO_SND, bufsize, NULL); 3861 } 3862 SOCKBUF_UNLOCK(&so->so_snd); 3863 /* 3864 * Sanity check: make sure that maxseg will be large 3865 * enough to allow some data on segments even if the 3866 * all the option space is used (40bytes). Otherwise 3867 * funny things may happen in tcp_output. 3868 * 3869 * XXXGL: shouldn't we reserve space for IP/IPv6 options? 3870 */ 3871 tp->t_maxseg = max(mss, 64); 3872 3873 SOCKBUF_LOCK(&so->so_rcv); 3874 if ((so->so_rcv.sb_hiwat == V_tcp_recvspace) && metrics.rmx_recvpipe) 3875 bufsize = metrics.rmx_recvpipe; 3876 else 3877 bufsize = so->so_rcv.sb_hiwat; 3878 if (bufsize > mss) { 3879 bufsize = roundup(bufsize, mss); 3880 if (bufsize > sb_max) 3881 bufsize = sb_max; 3882 if (bufsize > so->so_rcv.sb_hiwat) 3883 (void)sbreserve_locked(so, SO_RCV, bufsize, NULL); 3884 } 3885 SOCKBUF_UNLOCK(&so->so_rcv); 3886 3887 /* Check the interface for TSO capabilities. */ 3888 if (cap.ifcap & CSUM_TSO) { 3889 tp->t_flags |= TF_TSO; 3890 tp->t_tsomax = cap.tsomax; 3891 tp->t_tsomaxsegcount = cap.tsomaxsegcount; 3892 tp->t_tsomaxsegsize = cap.tsomaxsegsize; 3893 } 3894 } 3895 3896 /* 3897 * Determine the MSS option to send on an outgoing SYN. 3898 */ 3899 int 3900 tcp_mssopt(struct in_conninfo *inc) 3901 { 3902 int mss = 0; 3903 uint32_t thcmtu = 0; 3904 uint32_t maxmtu = 0; 3905 size_t min_protoh; 3906 3907 KASSERT(inc != NULL, ("tcp_mssopt with NULL in_conninfo pointer")); 3908 3909 #ifdef INET6 3910 if (inc->inc_flags & INC_ISIPV6) { 3911 mss = V_tcp_v6mssdflt; 3912 maxmtu = tcp_maxmtu6(inc, NULL); 3913 min_protoh = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 3914 } 3915 #endif 3916 #if defined(INET) && defined(INET6) 3917 else 3918 #endif 3919 #ifdef INET 3920 { 3921 mss = V_tcp_mssdflt; 3922 maxmtu = tcp_maxmtu(inc, NULL); 3923 min_protoh = sizeof(struct tcpiphdr); 3924 } 3925 #endif 3926 #if defined(INET6) || defined(INET) 3927 thcmtu = tcp_hc_getmtu(inc); /* IPv4 and IPv6 */ 3928 #endif 3929 3930 if (maxmtu && thcmtu) 3931 mss = min(maxmtu, thcmtu) - min_protoh; 3932 else if (maxmtu || thcmtu) 3933 mss = max(maxmtu, thcmtu) - min_protoh; 3934 3935 return (mss); 3936 } 3937 3938 void 3939 tcp_do_prr_ack(struct tcpcb *tp, struct tcphdr *th, struct tcpopt *to) 3940 { 3941 int snd_cnt = 0, limit = 0, del_data = 0, pipe = 0; 3942 int maxseg = tcp_maxseg(tp); 3943 3944 INP_WLOCK_ASSERT(tptoinpcb(tp)); 3945 3946 /* 3947 * Compute the amount of data that this ACK is indicating 3948 * (del_data) and an estimate of how many bytes are in the 3949 * network. 3950 */ 3951 if (tcp_is_sack_recovery(tp, to) || 3952 (IN_CONGRECOVERY(tp->t_flags) && 3953 !IN_FASTRECOVERY(tp->t_flags))) { 3954 del_data = tp->sackhint.delivered_data; 3955 if (V_tcp_do_newsack) 3956 pipe = tcp_compute_pipe(tp); 3957 else 3958 pipe = (tp->snd_nxt - tp->snd_fack) + 3959 tp->sackhint.sack_bytes_rexmit; 3960 } else { 3961 if (tp->sackhint.prr_delivered < (tcprexmtthresh * maxseg + 3962 tp->snd_recover - tp->snd_una)) 3963 del_data = maxseg; 3964 pipe = imax(0, tp->snd_max - tp->snd_una - 3965 imin(INT_MAX / 65536, tp->t_dupacks) * maxseg); 3966 } 3967 tp->sackhint.prr_delivered += del_data; 3968 /* 3969 * Proportional Rate Reduction 3970 */ 3971 if (pipe >= tp->snd_ssthresh) { 3972 if (tp->sackhint.recover_fs == 0) 3973 tp->sackhint.recover_fs = 3974 imax(1, tp->snd_nxt - tp->snd_una); 3975 snd_cnt = howmany((long)tp->sackhint.prr_delivered * 3976 tp->snd_ssthresh, tp->sackhint.recover_fs) - 3977 tp->sackhint.prr_out; 3978 } else { 3979 if (V_tcp_do_prr_conservative || (del_data == 0)) 3980 limit = tp->sackhint.prr_delivered - 3981 tp->sackhint.prr_out; 3982 else 3983 limit = imax(tp->sackhint.prr_delivered - 3984 tp->sackhint.prr_out, del_data) + 3985 maxseg; 3986 snd_cnt = imin((tp->snd_ssthresh - pipe), limit); 3987 } 3988 snd_cnt = imax(snd_cnt, 0) / maxseg; 3989 /* 3990 * Send snd_cnt new data into the network in response to this ack. 3991 * If there is going to be a SACK retransmission, adjust snd_cwnd 3992 * accordingly. 3993 */ 3994 if (IN_FASTRECOVERY(tp->t_flags)) { 3995 if (tcp_is_sack_recovery(tp, to)) { 3996 tp->snd_cwnd = tp->snd_nxt - tp->snd_recover + 3997 tp->sackhint.sack_bytes_rexmit + 3998 (snd_cnt * maxseg); 3999 } else { 4000 tp->snd_cwnd = (tp->snd_max - tp->snd_una) + 4001 (snd_cnt * maxseg); 4002 } 4003 } else if (IN_CONGRECOVERY(tp->t_flags)) 4004 tp->snd_cwnd = pipe - del_data + (snd_cnt * maxseg); 4005 tp->snd_cwnd = imax(maxseg, tp->snd_cwnd); 4006 } 4007 4008 /* 4009 * On a partial ack arrives, force the retransmission of the 4010 * next unacknowledged segment. Do not clear tp->t_dupacks. 4011 * By setting snd_nxt to ti_ack, this forces retransmission timer to 4012 * be started again. 4013 */ 4014 void 4015 tcp_newreno_partial_ack(struct tcpcb *tp, struct tcphdr *th) 4016 { 4017 tcp_seq onxt = tp->snd_nxt; 4018 uint32_t ocwnd = tp->snd_cwnd; 4019 u_int maxseg = tcp_maxseg(tp); 4020 4021 INP_WLOCK_ASSERT(tptoinpcb(tp)); 4022 4023 tcp_timer_activate(tp, TT_REXMT, 0); 4024 tp->t_rtttime = 0; 4025 tp->snd_nxt = th->th_ack; 4026 /* 4027 * Set snd_cwnd to one segment beyond acknowledged offset. 4028 * (tp->snd_una has not yet been updated when this function is called.) 4029 */ 4030 tp->snd_cwnd = maxseg + BYTES_THIS_ACK(tp, th); 4031 tp->t_flags |= TF_ACKNOW; 4032 (void) tcp_output(tp); 4033 tp->snd_cwnd = ocwnd; 4034 if (SEQ_GT(onxt, tp->snd_nxt)) 4035 tp->snd_nxt = onxt; 4036 /* 4037 * Partial window deflation. Relies on fact that tp->snd_una 4038 * not updated yet. 4039 */ 4040 if (tp->snd_cwnd > BYTES_THIS_ACK(tp, th)) 4041 tp->snd_cwnd -= BYTES_THIS_ACK(tp, th); 4042 else 4043 tp->snd_cwnd = 0; 4044 tp->snd_cwnd += maxseg; 4045 } 4046 4047 int 4048 tcp_compute_pipe(struct tcpcb *tp) 4049 { 4050 if (tp->t_fb->tfb_compute_pipe == NULL) { 4051 return (tp->snd_max - tp->snd_una + 4052 tp->sackhint.sack_bytes_rexmit - 4053 tp->sackhint.sacked_bytes); 4054 } else { 4055 return((*tp->t_fb->tfb_compute_pipe)(tp)); 4056 } 4057 } 4058 4059 uint32_t 4060 tcp_compute_initwnd(uint32_t maxseg) 4061 { 4062 /* 4063 * Calculate the Initial Window, also used as Restart Window 4064 * 4065 * RFC5681 Section 3.1 specifies the default conservative values. 4066 * RFC3390 specifies slightly more aggressive values. 4067 * RFC6928 increases it to ten segments. 4068 * Support for user specified value for initial flight size. 4069 */ 4070 if (V_tcp_initcwnd_segments) 4071 return min(V_tcp_initcwnd_segments * maxseg, 4072 max(2 * maxseg, V_tcp_initcwnd_segments * 1460)); 4073 else if (V_tcp_do_rfc3390) 4074 return min(4 * maxseg, max(2 * maxseg, 4380)); 4075 else { 4076 /* Per RFC5681 Section 3.1 */ 4077 if (maxseg > 2190) 4078 return (2 * maxseg); 4079 else if (maxseg > 1095) 4080 return (3 * maxseg); 4081 else 4082 return (4 * maxseg); 4083 } 4084 } 4085