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 #include "opt_inet.h" 54 #include "opt_inet6.h" 55 #include "opt_ipsec.h" 56 #include "opt_rss.h" 57 58 #include <sys/param.h> 59 #include <sys/arb.h> 60 #include <sys/kernel.h> 61 #ifdef TCP_HHOOK 62 #include <sys/hhook.h> 63 #endif 64 #include <sys/malloc.h> 65 #include <sys/mbuf.h> 66 #include <sys/proc.h> /* for proc0 declaration */ 67 #include <sys/protosw.h> 68 #include <sys/qmath.h> 69 #include <sys/sdt.h> 70 #include <sys/signalvar.h> 71 #include <sys/socket.h> 72 #include <sys/socketvar.h> 73 #include <sys/sysctl.h> 74 #include <sys/syslog.h> 75 #include <sys/systm.h> 76 #include <sys/stats.h> 77 78 #include <machine/cpu.h> /* before tcp_seq.h, for tcp_random18() */ 79 80 #include <vm/uma.h> 81 82 #include <net/if.h> 83 #include <net/if_var.h> 84 #include <net/route.h> 85 #include <net/rss_config.h> 86 #include <net/vnet.h> 87 88 #define TCPSTATES /* for logging */ 89 90 #include <netinet/in.h> 91 #include <netinet/in_kdtrace.h> 92 #include <netinet/in_pcb.h> 93 #include <netinet/in_rss.h> 94 #include <netinet/in_systm.h> 95 #include <netinet/ip.h> 96 #include <netinet/ip_icmp.h> /* required for icmp_var.h */ 97 #include <netinet/icmp_var.h> /* for ICMP_BANDLIM */ 98 #include <netinet/ip_var.h> 99 #include <netinet/ip_options.h> 100 #include <netinet/ip6.h> 101 #include <netinet/icmp6.h> 102 #include <netinet6/in6_pcb.h> 103 #include <netinet6/in6_rss.h> 104 #include <netinet6/in6_var.h> 105 #include <netinet6/ip6_var.h> 106 #include <netinet6/nd6.h> 107 #include <netinet/tcp.h> 108 #include <netinet/tcp_fsm.h> 109 #include <netinet/tcp_seq.h> 110 #include <netinet/tcp_timer.h> 111 #include <netinet/tcp_var.h> 112 #include <netinet/tcp_log_buf.h> 113 #include <netinet6/tcp6_var.h> 114 #include <netinet/tcpip.h> 115 #include <netinet/cc/cc.h> 116 #include <netinet/tcp_fastopen.h> 117 #ifdef TCPPCAP 118 #include <netinet/tcp_pcap.h> 119 #endif 120 #include <netinet/tcp_syncache.h> 121 #ifdef TCP_OFFLOAD 122 #include <netinet/tcp_offload.h> 123 #endif 124 #include <netinet/tcp_ecn.h> 125 #include <netinet/udp.h> 126 127 #include <netipsec/ipsec_support.h> 128 129 #include <machine/in_cksum.h> 130 131 #include <security/mac/mac_framework.h> 132 133 const int tcprexmtthresh = 3; 134 135 VNET_DEFINE(int, tcp_log_in_vain) = 0; 136 SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_in_vain, CTLFLAG_VNET | CTLFLAG_RW, 137 &VNET_NAME(tcp_log_in_vain), 0, 138 "Log all incoming TCP segments to closed ports"); 139 140 VNET_DEFINE(int, blackhole) = 0; 141 #define V_blackhole VNET(blackhole) 142 SYSCTL_INT(_net_inet_tcp, OID_AUTO, blackhole, CTLFLAG_VNET | CTLFLAG_RW, 143 &VNET_NAME(blackhole), 0, 144 "Do not send RST on segments to closed ports"); 145 146 VNET_DEFINE(bool, blackhole_local) = false; 147 #define V_blackhole_local VNET(blackhole_local) 148 SYSCTL_BOOL(_net_inet_tcp, OID_AUTO, blackhole_local, CTLFLAG_VNET | 149 CTLFLAG_RW, &VNET_NAME(blackhole_local), false, 150 "Enforce net.inet.tcp.blackhole for locally originated packets"); 151 152 VNET_DEFINE(int, tcp_delack_enabled) = 1; 153 SYSCTL_INT(_net_inet_tcp, OID_AUTO, delayed_ack, CTLFLAG_VNET | CTLFLAG_RW, 154 &VNET_NAME(tcp_delack_enabled), 0, 155 "Delay ACK to try and piggyback it onto a data packet"); 156 157 VNET_DEFINE(int, drop_synfin) = 0; 158 SYSCTL_INT(_net_inet_tcp, OID_AUTO, drop_synfin, CTLFLAG_VNET | CTLFLAG_RW, 159 &VNET_NAME(drop_synfin), 0, 160 "Drop TCP packets with SYN+FIN set"); 161 162 VNET_DEFINE(int, tcp_do_prr) = 1; 163 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_prr, CTLFLAG_VNET | CTLFLAG_RW, 164 &VNET_NAME(tcp_do_prr), 1, 165 "Enable Proportional Rate Reduction per RFC 6937"); 166 167 VNET_DEFINE(int, tcp_do_lrd) = 0; 168 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_lrd, CTLFLAG_VNET | CTLFLAG_RW, 169 &VNET_NAME(tcp_do_lrd), 1, 170 "Perform Lost Retransmission Detection"); 171 172 VNET_DEFINE(int, tcp_do_newcwv) = 0; 173 SYSCTL_INT(_net_inet_tcp, OID_AUTO, newcwv, CTLFLAG_VNET | CTLFLAG_RW, 174 &VNET_NAME(tcp_do_newcwv), 0, 175 "Enable New Congestion Window Validation per RFC7661"); 176 177 VNET_DEFINE(int, tcp_do_rfc3042) = 1; 178 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3042, CTLFLAG_VNET | CTLFLAG_RW, 179 &VNET_NAME(tcp_do_rfc3042), 0, 180 "Enable RFC 3042 (Limited Transmit)"); 181 182 VNET_DEFINE(int, tcp_do_rfc3390) = 1; 183 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3390, CTLFLAG_VNET | CTLFLAG_RW, 184 &VNET_NAME(tcp_do_rfc3390), 0, 185 "Enable RFC 3390 (Increasing TCP's Initial Congestion Window)"); 186 187 VNET_DEFINE(int, tcp_initcwnd_segments) = 10; 188 SYSCTL_INT(_net_inet_tcp, OID_AUTO, initcwnd_segments, 189 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(tcp_initcwnd_segments), 0, 190 "Slow-start flight size (initial congestion window) in number of segments"); 191 192 VNET_DEFINE(int, tcp_do_rfc3465) = 1; 193 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3465, CTLFLAG_VNET | CTLFLAG_RW, 194 &VNET_NAME(tcp_do_rfc3465), 0, 195 "Enable RFC 3465 (Appropriate Byte Counting)"); 196 197 VNET_DEFINE(int, tcp_abc_l_var) = 2; 198 SYSCTL_INT(_net_inet_tcp, OID_AUTO, abc_l_var, CTLFLAG_VNET | CTLFLAG_RW, 199 &VNET_NAME(tcp_abc_l_var), 2, 200 "Cap the max cwnd increment during slow-start to this number of segments"); 201 202 VNET_DEFINE(int, tcp_insecure_syn) = 0; 203 SYSCTL_INT(_net_inet_tcp, OID_AUTO, insecure_syn, CTLFLAG_VNET | CTLFLAG_RW, 204 &VNET_NAME(tcp_insecure_syn), 0, 205 "Follow RFC793 instead of RFC5961 criteria for accepting SYN packets"); 206 207 VNET_DEFINE(int, tcp_insecure_rst) = 0; 208 SYSCTL_INT(_net_inet_tcp, OID_AUTO, insecure_rst, CTLFLAG_VNET | CTLFLAG_RW, 209 &VNET_NAME(tcp_insecure_rst), 0, 210 "Follow RFC793 instead of RFC5961 criteria for accepting RST packets"); 211 212 VNET_DEFINE(int, tcp_recvspace) = 1024*64; 213 #define V_tcp_recvspace VNET(tcp_recvspace) 214 SYSCTL_INT(_net_inet_tcp, TCPCTL_RECVSPACE, recvspace, CTLFLAG_VNET | CTLFLAG_RW, 215 &VNET_NAME(tcp_recvspace), 0, "Initial receive socket buffer size"); 216 217 VNET_DEFINE(int, tcp_do_autorcvbuf) = 1; 218 SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_auto, CTLFLAG_VNET | CTLFLAG_RW, 219 &VNET_NAME(tcp_do_autorcvbuf), 0, 220 "Enable automatic receive buffer sizing"); 221 222 VNET_DEFINE(int, tcp_autorcvbuf_max) = 2*1024*1024; 223 SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_max, CTLFLAG_VNET | CTLFLAG_RW, 224 &VNET_NAME(tcp_autorcvbuf_max), 0, 225 "Max size of automatic receive buffer"); 226 227 VNET_DEFINE(struct inpcbinfo, tcbinfo); 228 229 /* 230 * TCP statistics are stored in an array of counter(9)s, which size matches 231 * size of struct tcpstat. TCP running connection count is a regular array. 232 */ 233 VNET_PCPUSTAT_DEFINE(struct tcpstat, tcpstat); 234 SYSCTL_VNET_PCPUSTAT(_net_inet_tcp, TCPCTL_STATS, stats, struct tcpstat, 235 tcpstat, "TCP statistics (struct tcpstat, netinet/tcp_var.h)"); 236 VNET_DEFINE(counter_u64_t, tcps_states[TCP_NSTATES]); 237 SYSCTL_COUNTER_U64_ARRAY(_net_inet_tcp, TCPCTL_STATES, states, CTLFLAG_RD | 238 CTLFLAG_VNET, &VNET_NAME(tcps_states)[0], TCP_NSTATES, 239 "TCP connection counts by TCP state"); 240 241 /* 242 * Kernel module interface for updating tcpstat. The first argument is an index 243 * into tcpstat treated as an array. 244 */ 245 void 246 kmod_tcpstat_add(int statnum, int val) 247 { 248 249 counter_u64_add(VNET(tcpstat)[statnum], val); 250 } 251 252 /* 253 * Make sure that we only start a SACK loss recovery when 254 * receiving a duplicate ACK with a SACK block, and also 255 * complete SACK loss recovery in case the other end 256 * reneges. 257 */ 258 static bool inline 259 tcp_is_sack_recovery(struct tcpcb *tp, struct tcpopt *to) 260 { 261 return ((tp->t_flags & TF_SACK_PERMIT) && 262 ((to->to_flags & TOF_SACK) || 263 (!TAILQ_EMPTY(&tp->snd_holes)))); 264 } 265 266 #ifdef TCP_HHOOK 267 /* 268 * Wrapper for the TCP established input helper hook. 269 */ 270 void 271 hhook_run_tcp_est_in(struct tcpcb *tp, struct tcphdr *th, struct tcpopt *to) 272 { 273 struct tcp_hhook_data hhook_data; 274 275 if (V_tcp_hhh[HHOOK_TCP_EST_IN]->hhh_nhooks > 0) { 276 hhook_data.tp = tp; 277 hhook_data.th = th; 278 hhook_data.to = to; 279 280 hhook_run_hooks(V_tcp_hhh[HHOOK_TCP_EST_IN], &hhook_data, 281 &tp->t_osd); 282 } 283 } 284 #endif 285 286 /* 287 * CC wrapper hook functions 288 */ 289 void 290 cc_ack_received(struct tcpcb *tp, struct tcphdr *th, uint16_t nsegs, 291 uint16_t type) 292 { 293 #ifdef STATS 294 int32_t gput; 295 #endif 296 297 INP_WLOCK_ASSERT(tptoinpcb(tp)); 298 299 tp->t_ccv.nsegs = nsegs; 300 tp->t_ccv.bytes_this_ack = BYTES_THIS_ACK(tp, th); 301 if ((!V_tcp_do_newcwv && (tp->snd_cwnd <= tp->snd_wnd)) || 302 (V_tcp_do_newcwv && (tp->snd_cwnd <= tp->snd_wnd) && 303 (tp->snd_cwnd < (tcp_compute_pipe(tp) * 2)))) 304 tp->t_ccv.flags |= CCF_CWND_LIMITED; 305 else 306 tp->t_ccv.flags &= ~CCF_CWND_LIMITED; 307 308 if (type == CC_ACK) { 309 #ifdef STATS 310 stats_voi_update_abs_s32(tp->t_stats, VOI_TCP_CALCFRWINDIFF, 311 ((int32_t)tp->snd_cwnd) - tp->snd_wnd); 312 if (!IN_RECOVERY(tp->t_flags)) 313 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_ACKLEN, 314 tp->t_ccv.bytes_this_ack / (tcp_maxseg(tp) * nsegs)); 315 if ((tp->t_flags & TF_GPUTINPROG) && 316 SEQ_GEQ(th->th_ack, tp->gput_ack)) { 317 /* 318 * Compute goodput in bits per millisecond. 319 */ 320 gput = (((int64_t)SEQ_SUB(th->th_ack, tp->gput_seq)) << 3) / 321 max(1, tcp_ts_getticks() - tp->gput_ts); 322 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_GPUT, 323 gput); 324 /* 325 * XXXLAS: This is a temporary hack, and should be 326 * chained off VOI_TCP_GPUT when stats(9) grows an API 327 * to deal with chained VOIs. 328 */ 329 if (tp->t_stats_gput_prev > 0) 330 stats_voi_update_abs_s32(tp->t_stats, 331 VOI_TCP_GPUT_ND, 332 ((gput - tp->t_stats_gput_prev) * 100) / 333 tp->t_stats_gput_prev); 334 tp->t_flags &= ~TF_GPUTINPROG; 335 tp->t_stats_gput_prev = gput; 336 } 337 #endif /* STATS */ 338 if (tp->snd_cwnd > tp->snd_ssthresh) { 339 tp->t_bytes_acked += tp->t_ccv.bytes_this_ack; 340 if (tp->t_bytes_acked >= tp->snd_cwnd) { 341 tp->t_bytes_acked -= tp->snd_cwnd; 342 tp->t_ccv.flags |= CCF_ABC_SENTAWND; 343 } 344 } else { 345 tp->t_ccv.flags &= ~CCF_ABC_SENTAWND; 346 tp->t_bytes_acked = 0; 347 } 348 } 349 350 if (CC_ALGO(tp)->ack_received != NULL) { 351 /* XXXLAS: Find a way to live without this */ 352 tp->t_ccv.curack = th->th_ack; 353 CC_ALGO(tp)->ack_received(&tp->t_ccv, type); 354 } 355 #ifdef STATS 356 stats_voi_update_abs_ulong(tp->t_stats, VOI_TCP_LCWIN, tp->snd_cwnd); 357 #endif 358 } 359 360 void 361 cc_conn_init(struct tcpcb *tp) 362 { 363 struct hc_metrics_lite metrics; 364 struct inpcb *inp = tptoinpcb(tp); 365 u_int maxseg; 366 int rtt; 367 368 INP_WLOCK_ASSERT(inp); 369 370 tcp_hc_get(&inp->inp_inc, &metrics); 371 maxseg = tcp_maxseg(tp); 372 373 if (tp->t_srtt == 0 && (rtt = metrics.rmx_rtt)) { 374 tp->t_srtt = rtt; 375 TCPSTAT_INC(tcps_usedrtt); 376 if (metrics.rmx_rttvar) { 377 tp->t_rttvar = metrics.rmx_rttvar; 378 TCPSTAT_INC(tcps_usedrttvar); 379 } else { 380 /* default variation is +- 1 rtt */ 381 tp->t_rttvar = 382 tp->t_srtt * TCP_RTTVAR_SCALE / TCP_RTT_SCALE; 383 } 384 TCPT_RANGESET(tp->t_rxtcur, 385 ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1, 386 tp->t_rttmin, TCPTV_REXMTMAX); 387 } 388 if (metrics.rmx_ssthresh) { 389 /* 390 * There's some sort of gateway or interface 391 * buffer limit on the path. Use this to set 392 * the slow start threshold, but set the 393 * threshold to no less than 2*mss. 394 */ 395 tp->snd_ssthresh = max(2 * maxseg, metrics.rmx_ssthresh); 396 TCPSTAT_INC(tcps_usedssthresh); 397 } 398 399 /* 400 * Set the initial slow-start flight size. 401 * 402 * If a SYN or SYN/ACK was lost and retransmitted, we have to 403 * reduce the initial CWND to one segment as congestion is likely 404 * requiring us to be cautious. 405 */ 406 if (tp->snd_cwnd == 1) 407 tp->snd_cwnd = maxseg; /* SYN(-ACK) lost */ 408 else 409 tp->snd_cwnd = tcp_compute_initwnd(maxseg); 410 411 if (CC_ALGO(tp)->conn_init != NULL) 412 CC_ALGO(tp)->conn_init(&tp->t_ccv); 413 } 414 415 void inline 416 cc_cong_signal(struct tcpcb *tp, struct tcphdr *th, uint32_t type) 417 { 418 INP_WLOCK_ASSERT(tptoinpcb(tp)); 419 420 #ifdef STATS 421 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_CSIG, type); 422 #endif 423 424 switch(type) { 425 case CC_NDUPACK: 426 if (!IN_FASTRECOVERY(tp->t_flags)) { 427 tp->snd_recover = tp->snd_max; 428 if (tp->t_flags2 & TF2_ECN_PERMIT) 429 tp->t_flags2 |= TF2_ECN_SND_CWR; 430 } 431 break; 432 case CC_ECN: 433 if (!IN_CONGRECOVERY(tp->t_flags) || 434 /* 435 * Allow ECN reaction on ACK to CWR, if 436 * that data segment was also CE marked. 437 */ 438 SEQ_GEQ(th->th_ack, tp->snd_recover)) { 439 EXIT_CONGRECOVERY(tp->t_flags); 440 TCPSTAT_INC(tcps_ecn_rcwnd); 441 tp->snd_recover = tp->snd_max + 1; 442 if (tp->t_flags2 & TF2_ECN_PERMIT) 443 tp->t_flags2 |= TF2_ECN_SND_CWR; 444 } 445 break; 446 case CC_RTO: 447 tp->t_dupacks = 0; 448 tp->t_bytes_acked = 0; 449 EXIT_RECOVERY(tp->t_flags); 450 if (tp->t_flags2 & TF2_ECN_PERMIT) 451 tp->t_flags2 |= TF2_ECN_SND_CWR; 452 break; 453 case CC_RTO_ERR: 454 TCPSTAT_INC(tcps_sndrexmitbad); 455 /* RTO was unnecessary, so reset everything. */ 456 tp->snd_cwnd = tp->snd_cwnd_prev; 457 tp->snd_ssthresh = tp->snd_ssthresh_prev; 458 tp->snd_recover = tp->snd_recover_prev; 459 if (tp->t_flags & TF_WASFRECOVERY) 460 ENTER_FASTRECOVERY(tp->t_flags); 461 if (tp->t_flags & TF_WASCRECOVERY) 462 ENTER_CONGRECOVERY(tp->t_flags); 463 tp->snd_nxt = tp->snd_max; 464 tp->t_flags &= ~TF_PREVVALID; 465 tp->t_badrxtwin = 0; 466 break; 467 } 468 469 if (CC_ALGO(tp)->cong_signal != NULL) { 470 if (th != NULL) 471 tp->t_ccv.curack = th->th_ack; 472 CC_ALGO(tp)->cong_signal(&tp->t_ccv, type); 473 } 474 } 475 476 void inline 477 cc_post_recovery(struct tcpcb *tp, struct tcphdr *th) 478 { 479 INP_WLOCK_ASSERT(tptoinpcb(tp)); 480 481 /* XXXLAS: KASSERT that we're in recovery? */ 482 483 if (CC_ALGO(tp)->post_recovery != NULL) { 484 tp->t_ccv.curack = th->th_ack; 485 CC_ALGO(tp)->post_recovery(&tp->t_ccv); 486 } 487 /* XXXLAS: EXIT_RECOVERY ? */ 488 tp->t_bytes_acked = 0; 489 tp->sackhint.delivered_data = 0; 490 tp->sackhint.prr_out = 0; 491 } 492 493 /* 494 * Indicate whether this ack should be delayed. We can delay the ack if 495 * following conditions are met: 496 * - There is no delayed ack timer in progress. 497 * - Our last ack wasn't a 0-sized window. We never want to delay 498 * the ack that opens up a 0-sized window. 499 * - LRO wasn't used for this segment. We make sure by checking that the 500 * segment size is not larger than the MSS. 501 */ 502 #define DELAY_ACK(tp, tlen) \ 503 ((!tcp_timer_active(tp, TT_DELACK) && \ 504 (tp->t_flags & TF_RXWIN0SENT) == 0) && \ 505 (tlen <= tp->t_maxseg) && \ 506 (V_tcp_delack_enabled || (tp->t_flags & TF_NEEDSYN))) 507 508 void inline 509 cc_ecnpkt_handler_flags(struct tcpcb *tp, uint16_t flags, uint8_t iptos) 510 { 511 INP_WLOCK_ASSERT(tptoinpcb(tp)); 512 513 if (CC_ALGO(tp)->ecnpkt_handler != NULL) { 514 switch (iptos & IPTOS_ECN_MASK) { 515 case IPTOS_ECN_CE: 516 tp->t_ccv.flags |= CCF_IPHDR_CE; 517 break; 518 case IPTOS_ECN_ECT0: 519 /* FALLTHROUGH */ 520 case IPTOS_ECN_ECT1: 521 /* FALLTHROUGH */ 522 case IPTOS_ECN_NOTECT: 523 tp->t_ccv.flags &= ~CCF_IPHDR_CE; 524 break; 525 } 526 527 if (flags & TH_CWR) 528 tp->t_ccv.flags |= CCF_TCPHDR_CWR; 529 else 530 tp->t_ccv.flags &= ~CCF_TCPHDR_CWR; 531 532 CC_ALGO(tp)->ecnpkt_handler(&tp->t_ccv); 533 534 if (tp->t_ccv.flags & CCF_ACKNOW) { 535 tcp_timer_activate(tp, TT_DELACK, tcp_delacktime); 536 tp->t_flags |= TF_ACKNOW; 537 } 538 } 539 } 540 541 void inline 542 cc_ecnpkt_handler(struct tcpcb *tp, struct tcphdr *th, uint8_t iptos) 543 { 544 cc_ecnpkt_handler_flags(tp, tcp_get_flags(th), iptos); 545 } 546 547 /* 548 * TCP input handling is split into multiple parts: 549 * tcp6_input is a thin wrapper around tcp_input for the extended 550 * ip6_protox[] call format in ip6_input 551 * tcp_input handles primary segment validation, inpcb lookup and 552 * SYN processing on listen sockets 553 * tcp_do_segment processes the ACK and text of the segment for 554 * establishing, established and closing connections 555 */ 556 #ifdef INET6 557 int 558 tcp6_input_with_port(struct mbuf **mp, int *offp, int proto, uint16_t port) 559 { 560 struct mbuf *m; 561 struct in6_ifaddr *ia6; 562 struct ip6_hdr *ip6; 563 564 m = *mp; 565 if (m->m_len < *offp + sizeof(struct tcphdr)) { 566 m = m_pullup(m, *offp + sizeof(struct tcphdr)); 567 if (m == NULL) { 568 *mp = m; 569 TCPSTAT_INC(tcps_rcvshort); 570 return (IPPROTO_DONE); 571 } 572 } 573 574 /* 575 * draft-itojun-ipv6-tcp-to-anycast 576 * better place to put this in? 577 */ 578 ip6 = mtod(m, struct ip6_hdr *); 579 ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */, false); 580 if (ia6 && (ia6->ia6_flags & IN6_IFF_ANYCAST)) { 581 icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR, 582 (caddr_t)&ip6->ip6_dst - (caddr_t)ip6); 583 *mp = NULL; 584 return (IPPROTO_DONE); 585 } 586 587 *mp = m; 588 return (tcp_input_with_port(mp, offp, proto, port)); 589 } 590 591 int 592 tcp6_input(struct mbuf **mp, int *offp, int proto) 593 { 594 595 return(tcp6_input_with_port(mp, offp, proto, 0)); 596 } 597 #endif /* INET6 */ 598 599 int 600 tcp_input_with_port(struct mbuf **mp, int *offp, int proto, uint16_t port) 601 { 602 struct mbuf *m = *mp; 603 struct tcphdr *th = NULL; 604 struct ip *ip = NULL; 605 struct inpcb *inp = NULL; 606 struct tcpcb *tp = NULL; 607 struct socket *so = NULL; 608 u_char *optp = NULL; 609 int off0; 610 int optlen = 0; 611 #ifdef INET 612 int len; 613 uint8_t ipttl; 614 #endif 615 int tlen = 0, off; 616 int drop_hdrlen; 617 int thflags; 618 int rstreason = 0; /* For badport_bandlim accounting purposes */ 619 int lookupflag; 620 uint8_t iptos; 621 struct m_tag *fwd_tag = NULL; 622 #ifdef INET6 623 struct ip6_hdr *ip6 = NULL; 624 int isipv6; 625 #else 626 const void *ip6 = NULL; 627 #endif /* INET6 */ 628 struct tcpopt to; /* options in this segment */ 629 char *s = NULL; /* address and port logging */ 630 631 NET_EPOCH_ASSERT(); 632 633 #ifdef INET6 634 isipv6 = (mtod(m, struct ip *)->ip_v == 6) ? 1 : 0; 635 #endif 636 637 off0 = *offp; 638 m = *mp; 639 *mp = NULL; 640 to.to_flags = 0; 641 TCPSTAT_INC(tcps_rcvtotal); 642 643 #ifdef INET6 644 if (isipv6) { 645 ip6 = mtod(m, struct ip6_hdr *); 646 th = (struct tcphdr *)((caddr_t)ip6 + off0); 647 tlen = sizeof(*ip6) + ntohs(ip6->ip6_plen) - off0; 648 if (port) 649 goto skip6_csum; 650 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID_IPV6) { 651 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 652 th->th_sum = m->m_pkthdr.csum_data; 653 else 654 th->th_sum = in6_cksum_pseudo(ip6, tlen, 655 IPPROTO_TCP, m->m_pkthdr.csum_data); 656 th->th_sum ^= 0xffff; 657 } else 658 th->th_sum = in6_cksum(m, IPPROTO_TCP, off0, tlen); 659 if (th->th_sum) { 660 TCPSTAT_INC(tcps_rcvbadsum); 661 goto drop; 662 } 663 skip6_csum: 664 /* 665 * Be proactive about unspecified IPv6 address in source. 666 * As we use all-zero to indicate unbounded/unconnected pcb, 667 * unspecified IPv6 address can be used to confuse us. 668 * 669 * Note that packets with unspecified IPv6 destination is 670 * already dropped in ip6_input. 671 */ 672 KASSERT(!IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_dst), 673 ("%s: unspecified destination v6 address", __func__)); 674 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 675 IP6STAT_INC(ip6s_badscope); /* XXX */ 676 goto drop; 677 } 678 iptos = IPV6_TRAFFIC_CLASS(ip6); 679 } 680 #endif 681 #if defined(INET) && defined(INET6) 682 else 683 #endif 684 #ifdef INET 685 { 686 /* 687 * Get IP and TCP header together in first mbuf. 688 * Note: IP leaves IP header in first mbuf. 689 */ 690 if (off0 > sizeof (struct ip)) { 691 ip_stripoptions(m); 692 off0 = sizeof(struct ip); 693 } 694 if (m->m_len < sizeof (struct tcpiphdr)) { 695 if ((m = m_pullup(m, sizeof (struct tcpiphdr))) 696 == NULL) { 697 TCPSTAT_INC(tcps_rcvshort); 698 return (IPPROTO_DONE); 699 } 700 } 701 ip = mtod(m, struct ip *); 702 th = (struct tcphdr *)((caddr_t)ip + off0); 703 tlen = ntohs(ip->ip_len) - off0; 704 705 iptos = ip->ip_tos; 706 if (port) 707 goto skip_csum; 708 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) { 709 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 710 th->th_sum = m->m_pkthdr.csum_data; 711 else 712 th->th_sum = in_pseudo(ip->ip_src.s_addr, 713 ip->ip_dst.s_addr, 714 htonl(m->m_pkthdr.csum_data + tlen + 715 IPPROTO_TCP)); 716 th->th_sum ^= 0xffff; 717 } else { 718 struct ipovly *ipov = (struct ipovly *)ip; 719 720 /* 721 * Checksum extended TCP header and data. 722 */ 723 len = off0 + tlen; 724 ipttl = ip->ip_ttl; 725 bzero(ipov->ih_x1, sizeof(ipov->ih_x1)); 726 ipov->ih_len = htons(tlen); 727 th->th_sum = in_cksum(m, len); 728 /* Reset length for SDT probes. */ 729 ip->ip_len = htons(len); 730 /* Reset TOS bits */ 731 ip->ip_tos = iptos; 732 /* Re-initialization for later version check */ 733 ip->ip_ttl = ipttl; 734 ip->ip_v = IPVERSION; 735 ip->ip_hl = off0 >> 2; 736 } 737 skip_csum: 738 if (th->th_sum && (port == 0)) { 739 TCPSTAT_INC(tcps_rcvbadsum); 740 goto drop; 741 } 742 KASSERT(ip->ip_dst.s_addr != INADDR_ANY, 743 ("%s: unspecified destination v4 address", __func__)); 744 if (__predict_false(ip->ip_src.s_addr == INADDR_ANY)) { 745 IPSTAT_INC(ips_badaddr); 746 goto drop; 747 } 748 } 749 #endif /* INET */ 750 751 /* 752 * Check that TCP offset makes sense, 753 * pull out TCP options and adjust length. XXX 754 */ 755 off = th->th_off << 2; 756 if (off < sizeof (struct tcphdr) || off > tlen) { 757 TCPSTAT_INC(tcps_rcvbadoff); 758 goto drop; 759 } 760 tlen -= off; /* tlen is used instead of ti->ti_len */ 761 if (off > sizeof (struct tcphdr)) { 762 #ifdef INET6 763 if (isipv6) { 764 if (m->m_len < off0 + off) { 765 m = m_pullup(m, off0 + off); 766 if (m == NULL) { 767 TCPSTAT_INC(tcps_rcvshort); 768 return (IPPROTO_DONE); 769 } 770 } 771 ip6 = mtod(m, struct ip6_hdr *); 772 th = (struct tcphdr *)((caddr_t)ip6 + off0); 773 } 774 #endif 775 #if defined(INET) && defined(INET6) 776 else 777 #endif 778 #ifdef INET 779 { 780 if (m->m_len < sizeof(struct ip) + off) { 781 if ((m = m_pullup(m, sizeof (struct ip) + off)) 782 == NULL) { 783 TCPSTAT_INC(tcps_rcvshort); 784 return (IPPROTO_DONE); 785 } 786 ip = mtod(m, struct ip *); 787 th = (struct tcphdr *)((caddr_t)ip + off0); 788 } 789 } 790 #endif 791 optlen = off - sizeof (struct tcphdr); 792 optp = (u_char *)(th + 1); 793 } 794 thflags = tcp_get_flags(th); 795 796 /* 797 * Convert TCP protocol specific fields to host format. 798 */ 799 tcp_fields_to_host(th); 800 801 /* 802 * Delay dropping TCP, IP headers, IPv6 ext headers, and TCP options. 803 */ 804 drop_hdrlen = off0 + off; 805 806 /* 807 * Grab info from PACKET_TAG_IPFORWARD tag prepended to the chain. 808 */ 809 if ( 810 #ifdef INET6 811 (isipv6 && (m->m_flags & M_IP6_NEXTHOP)) 812 #ifdef INET 813 || (!isipv6 && (m->m_flags & M_IP_NEXTHOP)) 814 #endif 815 #endif 816 #if defined(INET) && !defined(INET6) 817 (m->m_flags & M_IP_NEXTHOP) 818 #endif 819 ) 820 fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL); 821 822 /* 823 * For initial SYN packets we don't need write lock on matching 824 * PCB, be it a listening one or a synchronized one. The packet 825 * shall not modify its state. 826 */ 827 lookupflag = INPLOOKUP_WILDCARD | 828 ((thflags & (TH_ACK|TH_SYN)) == TH_SYN ? 829 INPLOOKUP_RLOCKPCB : INPLOOKUP_WLOCKPCB); 830 findpcb: 831 #ifdef INET6 832 if (isipv6 && fwd_tag != NULL) { 833 struct sockaddr_in6 *next_hop6; 834 835 next_hop6 = (struct sockaddr_in6 *)(fwd_tag + 1); 836 /* 837 * Transparently forwarded. Pretend to be the destination. 838 * Already got one like this? 839 */ 840 inp = in6_pcblookup_mbuf(&V_tcbinfo, 841 &ip6->ip6_src, th->th_sport, &ip6->ip6_dst, th->th_dport, 842 lookupflag & ~INPLOOKUP_WILDCARD, m->m_pkthdr.rcvif, m); 843 if (!inp) { 844 /* 845 * It's new. Try to find the ambushing socket. 846 * Because we've rewritten the destination address, 847 * any hardware-generated hash is ignored. 848 */ 849 inp = in6_pcblookup(&V_tcbinfo, &ip6->ip6_src, 850 th->th_sport, &next_hop6->sin6_addr, 851 next_hop6->sin6_port ? ntohs(next_hop6->sin6_port) : 852 th->th_dport, lookupflag, m->m_pkthdr.rcvif); 853 } 854 } else if (isipv6) { 855 inp = in6_pcblookup_mbuf(&V_tcbinfo, &ip6->ip6_src, 856 th->th_sport, &ip6->ip6_dst, th->th_dport, lookupflag, 857 m->m_pkthdr.rcvif, m); 858 } 859 #endif /* INET6 */ 860 #if defined(INET6) && defined(INET) 861 else 862 #endif 863 #ifdef INET 864 if (fwd_tag != NULL) { 865 struct sockaddr_in *next_hop; 866 867 next_hop = (struct sockaddr_in *)(fwd_tag+1); 868 /* 869 * Transparently forwarded. Pretend to be the destination. 870 * already got one like this? 871 */ 872 inp = in_pcblookup_mbuf(&V_tcbinfo, ip->ip_src, th->th_sport, 873 ip->ip_dst, th->th_dport, lookupflag & ~INPLOOKUP_WILDCARD, 874 m->m_pkthdr.rcvif, m); 875 if (!inp) { 876 /* 877 * It's new. Try to find the ambushing socket. 878 * Because we've rewritten the destination address, 879 * any hardware-generated hash is ignored. 880 */ 881 inp = in_pcblookup(&V_tcbinfo, ip->ip_src, 882 th->th_sport, next_hop->sin_addr, 883 next_hop->sin_port ? ntohs(next_hop->sin_port) : 884 th->th_dport, lookupflag, m->m_pkthdr.rcvif); 885 } 886 } else 887 inp = in_pcblookup_mbuf(&V_tcbinfo, ip->ip_src, 888 th->th_sport, ip->ip_dst, th->th_dport, lookupflag, 889 m->m_pkthdr.rcvif, m); 890 #endif /* INET */ 891 892 /* 893 * If the INPCB does not exist then all data in the incoming 894 * segment is discarded and an appropriate RST is sent back. 895 * XXX MRT Send RST using which routing table? 896 */ 897 if (inp == NULL) { 898 if (rstreason != 0) { 899 /* We came here after second (safety) lookup. */ 900 MPASS((lookupflag & INPLOOKUP_WILDCARD) == 0); 901 goto dropwithreset; 902 } 903 /* 904 * Log communication attempts to ports that are not 905 * in use. 906 */ 907 if ((V_tcp_log_in_vain == 1 && (thflags & TH_SYN)) || 908 V_tcp_log_in_vain == 2) { 909 if ((s = tcp_log_vain(NULL, th, (void *)ip, ip6))) 910 log(LOG_INFO, "%s; %s: Connection attempt " 911 "to closed port\n", s, __func__); 912 } 913 /* 914 * When blackholing do not respond with a RST but 915 * completely ignore the segment and drop it. 916 */ 917 if (((V_blackhole == 1 && (thflags & TH_SYN)) || 918 V_blackhole == 2) && (V_blackhole_local || ( 919 #ifdef INET6 920 isipv6 ? !in6_localaddr(&ip6->ip6_src) : 921 #endif 922 #ifdef INET 923 !in_localip(ip->ip_src) 924 #else 925 true 926 #endif 927 ))) 928 goto dropunlock; 929 930 rstreason = BANDLIM_RST_CLOSEDPORT; 931 goto dropwithreset; 932 } 933 INP_LOCK_ASSERT(inp); 934 935 if ((inp->inp_flowtype == M_HASHTYPE_NONE) && 936 !SOLISTENING(inp->inp_socket)) { 937 if (M_HASHTYPE_GET(m) != M_HASHTYPE_NONE) { 938 inp->inp_flowid = m->m_pkthdr.flowid; 939 inp->inp_flowtype = M_HASHTYPE_GET(m); 940 #ifdef RSS 941 } else { 942 /* assign flowid by software RSS hash */ 943 #ifdef INET6 944 if (isipv6) { 945 rss_proto_software_hash_v6(&inp->in6p_faddr, 946 &inp->in6p_laddr, 947 inp->inp_fport, 948 inp->inp_lport, 949 IPPROTO_TCP, 950 &inp->inp_flowid, 951 &inp->inp_flowtype); 952 } else 953 #endif /* INET6 */ 954 { 955 rss_proto_software_hash_v4(inp->inp_faddr, 956 inp->inp_laddr, 957 inp->inp_fport, 958 inp->inp_lport, 959 IPPROTO_TCP, 960 &inp->inp_flowid, 961 &inp->inp_flowtype); 962 } 963 #endif /* RSS */ 964 } 965 } 966 #if defined(IPSEC) || defined(IPSEC_SUPPORT) 967 #ifdef INET6 968 if (isipv6 && IPSEC_ENABLED(ipv6) && 969 IPSEC_CHECK_POLICY(ipv6, m, inp) != 0) { 970 goto dropunlock; 971 } 972 #ifdef INET 973 else 974 #endif 975 #endif /* INET6 */ 976 #ifdef INET 977 if (IPSEC_ENABLED(ipv4) && 978 IPSEC_CHECK_POLICY(ipv4, m, inp) != 0) { 979 goto dropunlock; 980 } 981 #endif /* INET */ 982 #endif /* IPSEC */ 983 984 /* 985 * Check the minimum TTL for socket. 986 */ 987 if (inp->inp_ip_minttl != 0) { 988 #ifdef INET6 989 if (isipv6) { 990 if (inp->inp_ip_minttl > ip6->ip6_hlim) 991 goto dropunlock; 992 } else 993 #endif 994 if (inp->inp_ip_minttl > ip->ip_ttl) 995 goto dropunlock; 996 } 997 998 tp = intotcpcb(inp); 999 switch (tp->t_state) { 1000 case TCPS_TIME_WAIT: 1001 /* 1002 * A previous connection in TIMEWAIT state is supposed to catch 1003 * stray or duplicate segments arriving late. If this segment 1004 * was a legitimate new connection attempt, the old INPCB gets 1005 * removed and we can try again to find a listening socket. 1006 */ 1007 tcp_dooptions(&to, optp, optlen, 1008 (thflags & TH_SYN) ? TO_SYN : 0); 1009 /* 1010 * tcp_twcheck unlocks the inp always, and frees the m if fails. 1011 */ 1012 if (tcp_twcheck(inp, &to, th, m, tlen)) 1013 goto findpcb; 1014 return (IPPROTO_DONE); 1015 case TCPS_CLOSED: 1016 /* 1017 * The TCPCB may no longer exist if the connection is winding 1018 * down or it is in the CLOSED state. Either way we drop the 1019 * segment and send an appropriate response. 1020 */ 1021 rstreason = BANDLIM_RST_CLOSEDPORT; 1022 goto dropwithreset; 1023 } 1024 1025 if ((tp->t_port != port) && (tp->t_state > TCPS_LISTEN)) { 1026 rstreason = BANDLIM_RST_CLOSEDPORT; 1027 goto dropwithreset; 1028 } 1029 1030 #ifdef TCP_OFFLOAD 1031 if (tp->t_flags & TF_TOE) { 1032 tcp_offload_input(tp, m); 1033 m = NULL; /* consumed by the TOE driver */ 1034 goto dropunlock; 1035 } 1036 #endif 1037 1038 #ifdef MAC 1039 if (mac_inpcb_check_deliver(inp, m)) 1040 goto dropunlock; 1041 #endif 1042 so = inp->inp_socket; 1043 KASSERT(so != NULL, ("%s: so == NULL", __func__)); 1044 /* 1045 * When the socket is accepting connections (the INPCB is in LISTEN 1046 * state) we look into the SYN cache if this is a new connection 1047 * attempt or the completion of a previous one. 1048 */ 1049 KASSERT(tp->t_state == TCPS_LISTEN || !SOLISTENING(so), 1050 ("%s: so accepting but tp %p not listening", __func__, tp)); 1051 if (tp->t_state == TCPS_LISTEN && SOLISTENING(so)) { 1052 struct in_conninfo inc; 1053 1054 bzero(&inc, sizeof(inc)); 1055 #ifdef INET6 1056 if (isipv6) { 1057 inc.inc_flags |= INC_ISIPV6; 1058 if (inp->inp_inc.inc_flags & INC_IPV6MINMTU) 1059 inc.inc_flags |= INC_IPV6MINMTU; 1060 inc.inc6_faddr = ip6->ip6_src; 1061 inc.inc6_laddr = ip6->ip6_dst; 1062 } else 1063 #endif 1064 { 1065 inc.inc_faddr = ip->ip_src; 1066 inc.inc_laddr = ip->ip_dst; 1067 } 1068 inc.inc_fport = th->th_sport; 1069 inc.inc_lport = th->th_dport; 1070 inc.inc_fibnum = so->so_fibnum; 1071 1072 /* 1073 * Check for an existing connection attempt in syncache if 1074 * the flag is only ACK. A successful lookup creates a new 1075 * socket appended to the listen queue in SYN_RECEIVED state. 1076 */ 1077 if ((thflags & (TH_RST|TH_ACK|TH_SYN)) == TH_ACK) { 1078 /* 1079 * Parse the TCP options here because 1080 * syncookies need access to the reflected 1081 * timestamp. 1082 */ 1083 tcp_dooptions(&to, optp, optlen, 0); 1084 /* 1085 * NB: syncache_expand() doesn't unlock inp. 1086 */ 1087 rstreason = syncache_expand(&inc, &to, th, &so, m, port); 1088 if (rstreason < 0) { 1089 /* 1090 * A failing TCP MD5 signature comparison 1091 * must result in the segment being dropped 1092 * and must not produce any response back 1093 * to the sender. 1094 */ 1095 goto dropunlock; 1096 } else if (rstreason == 0) { 1097 /* 1098 * No syncache entry, or ACK was not for our 1099 * SYN/ACK. Do our protection against double 1100 * ACK. If peer sent us 2 ACKs, then for the 1101 * first one syncache_expand() successfully 1102 * converted syncache entry into a socket, 1103 * while we were waiting on the inpcb lock. We 1104 * don't want to sent RST for the second ACK, 1105 * so we perform second lookup without wildcard 1106 * match, hoping to find the new socket. If 1107 * the ACK is stray indeed, rstreason would 1108 * hint the above code that the lookup was a 1109 * second attempt. 1110 * 1111 * NB: syncache did its own logging 1112 * of the failure cause. 1113 */ 1114 INP_WUNLOCK(inp); 1115 rstreason = BANDLIM_RST_OPENPORT; 1116 lookupflag &= ~INPLOOKUP_WILDCARD; 1117 goto findpcb; 1118 } 1119 tfo_socket_result: 1120 if (so == NULL) { 1121 /* 1122 * We completed the 3-way handshake 1123 * but could not allocate a socket 1124 * either due to memory shortage, 1125 * listen queue length limits or 1126 * global socket limits. Send RST 1127 * or wait and have the remote end 1128 * retransmit the ACK for another 1129 * try. 1130 */ 1131 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1132 log(LOG_DEBUG, "%s; %s: Listen socket: " 1133 "Socket allocation failed due to " 1134 "limits or memory shortage, %s\n", 1135 s, __func__, 1136 V_tcp_sc_rst_sock_fail ? 1137 "sending RST" : "try again"); 1138 if (V_tcp_sc_rst_sock_fail) { 1139 rstreason = BANDLIM_UNLIMITED; 1140 goto dropwithreset; 1141 } else 1142 goto dropunlock; 1143 } 1144 /* 1145 * Socket is created in state SYN_RECEIVED. 1146 * Unlock the listen socket, lock the newly 1147 * created socket and update the tp variable. 1148 * If we came here via jump to tfo_socket_result, 1149 * then listening socket is read-locked. 1150 */ 1151 INP_UNLOCK(inp); /* listen socket */ 1152 inp = sotoinpcb(so); 1153 /* 1154 * New connection inpcb is already locked by 1155 * syncache_expand(). 1156 */ 1157 INP_WLOCK_ASSERT(inp); 1158 tp = intotcpcb(inp); 1159 KASSERT(tp->t_state == TCPS_SYN_RECEIVED, 1160 ("%s: ", __func__)); 1161 /* 1162 * Process the segment and the data it 1163 * contains. tcp_do_segment() consumes 1164 * the mbuf chain and unlocks the inpcb. 1165 */ 1166 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1167 tp->t_fb->tfb_tcp_do_segment(tp, m, th, drop_hdrlen, 1168 tlen, iptos); 1169 return (IPPROTO_DONE); 1170 } 1171 /* 1172 * Segment flag validation for new connection attempts: 1173 * 1174 * Our (SYN|ACK) response was rejected. 1175 * Check with syncache and remove entry to prevent 1176 * retransmits. 1177 * 1178 * NB: syncache_chkrst does its own logging of failure 1179 * causes. 1180 */ 1181 if (thflags & TH_RST) { 1182 syncache_chkrst(&inc, th, m, port); 1183 goto dropunlock; 1184 } 1185 /* 1186 * We can't do anything without SYN. 1187 */ 1188 if ((thflags & TH_SYN) == 0) { 1189 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1190 log(LOG_DEBUG, "%s; %s: Listen socket: " 1191 "SYN is missing, segment ignored\n", 1192 s, __func__); 1193 TCPSTAT_INC(tcps_badsyn); 1194 goto dropunlock; 1195 } 1196 /* 1197 * (SYN|ACK) is bogus on a listen socket. 1198 */ 1199 if (thflags & TH_ACK) { 1200 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1201 log(LOG_DEBUG, "%s; %s: Listen socket: " 1202 "SYN|ACK invalid, segment rejected\n", 1203 s, __func__); 1204 syncache_badack(&inc, port); /* XXX: Not needed! */ 1205 TCPSTAT_INC(tcps_badsyn); 1206 rstreason = BANDLIM_RST_OPENPORT; 1207 goto dropwithreset; 1208 } 1209 /* 1210 * If the drop_synfin option is enabled, drop all 1211 * segments with both the SYN and FIN bits set. 1212 * This prevents e.g. nmap from identifying the 1213 * TCP/IP stack. 1214 * XXX: Poor reasoning. nmap has other methods 1215 * and is constantly refining its stack detection 1216 * strategies. 1217 * XXX: This is a violation of the TCP specification 1218 * and was used by RFC1644. 1219 */ 1220 if ((thflags & TH_FIN) && V_drop_synfin) { 1221 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1222 log(LOG_DEBUG, "%s; %s: Listen socket: " 1223 "SYN|FIN segment ignored (based on " 1224 "sysctl setting)\n", s, __func__); 1225 TCPSTAT_INC(tcps_badsyn); 1226 goto dropunlock; 1227 } 1228 /* 1229 * Segment's flags are (SYN) or (SYN|FIN). 1230 * 1231 * TH_PUSH, TH_URG, TH_ECE, TH_CWR are ignored 1232 * as they do not affect the state of the TCP FSM. 1233 * The data pointed to by TH_URG and th_urp is ignored. 1234 */ 1235 KASSERT((thflags & (TH_RST|TH_ACK)) == 0, 1236 ("%s: Listen socket: TH_RST or TH_ACK set", __func__)); 1237 KASSERT(thflags & (TH_SYN), 1238 ("%s: Listen socket: TH_SYN not set", __func__)); 1239 INP_RLOCK_ASSERT(inp); 1240 #ifdef INET6 1241 /* 1242 * If deprecated address is forbidden, 1243 * we do not accept SYN to deprecated interface 1244 * address to prevent any new inbound connection from 1245 * getting established. 1246 * When we do not accept SYN, we send a TCP RST, 1247 * with deprecated source address (instead of dropping 1248 * it). We compromise it as it is much better for peer 1249 * to send a RST, and RST will be the final packet 1250 * for the exchange. 1251 * 1252 * If we do not forbid deprecated addresses, we accept 1253 * the SYN packet. RFC2462 does not suggest dropping 1254 * SYN in this case. 1255 * If we decipher RFC2462 5.5.4, it says like this: 1256 * 1. use of deprecated addr with existing 1257 * communication is okay - "SHOULD continue to be 1258 * used" 1259 * 2. use of it with new communication: 1260 * (2a) "SHOULD NOT be used if alternate address 1261 * with sufficient scope is available" 1262 * (2b) nothing mentioned otherwise. 1263 * Here we fall into (2b) case as we have no choice in 1264 * our source address selection - we must obey the peer. 1265 * 1266 * The wording in RFC2462 is confusing, and there are 1267 * multiple description text for deprecated address 1268 * handling - worse, they are not exactly the same. 1269 * I believe 5.5.4 is the best one, so we follow 5.5.4. 1270 */ 1271 if (isipv6 && !V_ip6_use_deprecated) { 1272 struct in6_ifaddr *ia6; 1273 1274 ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */, false); 1275 if (ia6 != NULL && 1276 (ia6->ia6_flags & IN6_IFF_DEPRECATED)) { 1277 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1278 log(LOG_DEBUG, "%s; %s: Listen socket: " 1279 "Connection attempt to deprecated " 1280 "IPv6 address rejected\n", 1281 s, __func__); 1282 rstreason = BANDLIM_RST_OPENPORT; 1283 goto dropwithreset; 1284 } 1285 } 1286 #endif /* INET6 */ 1287 /* 1288 * Basic sanity checks on incoming SYN requests: 1289 * Don't respond if the destination is a link layer 1290 * broadcast according to RFC1122 4.2.3.10, p. 104. 1291 * If it is from this socket it must be forged. 1292 * Don't respond if the source or destination is a 1293 * global or subnet broad- or multicast address. 1294 * Note that it is quite possible to receive unicast 1295 * link-layer packets with a broadcast IP address. Use 1296 * in_broadcast() to find them. 1297 */ 1298 if (m->m_flags & (M_BCAST|M_MCAST)) { 1299 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1300 log(LOG_DEBUG, "%s; %s: Listen socket: " 1301 "Connection attempt from broad- or multicast " 1302 "link layer address ignored\n", s, __func__); 1303 goto dropunlock; 1304 } 1305 #ifdef INET6 1306 if (isipv6) { 1307 if (th->th_dport == th->th_sport && 1308 IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &ip6->ip6_src)) { 1309 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1310 log(LOG_DEBUG, "%s; %s: Listen socket: " 1311 "Connection attempt to/from self " 1312 "ignored\n", s, __func__); 1313 goto dropunlock; 1314 } 1315 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 1316 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) { 1317 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1318 log(LOG_DEBUG, "%s; %s: Listen socket: " 1319 "Connection attempt from/to multicast " 1320 "address ignored\n", s, __func__); 1321 goto dropunlock; 1322 } 1323 } 1324 #endif 1325 #if defined(INET) && defined(INET6) 1326 else 1327 #endif 1328 #ifdef INET 1329 { 1330 if (th->th_dport == th->th_sport && 1331 ip->ip_dst.s_addr == ip->ip_src.s_addr) { 1332 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1333 log(LOG_DEBUG, "%s; %s: Listen socket: " 1334 "Connection attempt from/to self " 1335 "ignored\n", s, __func__); 1336 goto dropunlock; 1337 } 1338 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || 1339 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 1340 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || 1341 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) { 1342 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1343 log(LOG_DEBUG, "%s; %s: Listen socket: " 1344 "Connection attempt from/to broad- " 1345 "or multicast address ignored\n", 1346 s, __func__); 1347 goto dropunlock; 1348 } 1349 } 1350 #endif 1351 /* 1352 * SYN appears to be valid. Create compressed TCP state 1353 * for syncache. 1354 */ 1355 TCP_PROBE3(debug__input, tp, th, m); 1356 tcp_dooptions(&to, optp, optlen, TO_SYN); 1357 if ((so = syncache_add(&inc, &to, th, inp, so, m, NULL, NULL, 1358 iptos, port)) != NULL) 1359 goto tfo_socket_result; 1360 1361 /* 1362 * Entry added to syncache and mbuf consumed. 1363 * Only the listen socket is unlocked by syncache_add(). 1364 */ 1365 return (IPPROTO_DONE); 1366 } else if (tp->t_state == TCPS_LISTEN) { 1367 /* 1368 * When a listen socket is torn down the SO_ACCEPTCONN 1369 * flag is removed first while connections are drained 1370 * from the accept queue in a unlock/lock cycle of the 1371 * ACCEPT_LOCK, opening a race condition allowing a SYN 1372 * attempt go through unhandled. 1373 */ 1374 goto dropunlock; 1375 } 1376 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 1377 if (tp->t_flags & TF_SIGNATURE) { 1378 tcp_dooptions(&to, optp, optlen, thflags); 1379 if ((to.to_flags & TOF_SIGNATURE) == 0) { 1380 TCPSTAT_INC(tcps_sig_err_nosigopt); 1381 goto dropunlock; 1382 } 1383 if (!TCPMD5_ENABLED() || 1384 TCPMD5_INPUT(m, th, to.to_signature) != 0) 1385 goto dropunlock; 1386 } 1387 #endif 1388 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1389 1390 /* 1391 * Segment belongs to a connection in SYN_SENT, ESTABLISHED or later 1392 * state. tcp_do_segment() always consumes the mbuf chain, unlocks 1393 * the inpcb, and unlocks pcbinfo. 1394 * 1395 * XXXGL: in case of a pure SYN arriving on existing connection 1396 * TCP stacks won't need to modify the PCB, they would either drop 1397 * the segment silently, or send a challenge ACK. However, we try 1398 * to upgrade the lock, because calling convention for stacks is 1399 * write-lock on PCB. If upgrade fails, drop the SYN. 1400 */ 1401 if ((lookupflag & INPLOOKUP_RLOCKPCB) && INP_TRY_UPGRADE(inp) == 0) 1402 goto dropunlock; 1403 1404 tp->t_fb->tfb_tcp_do_segment(tp, m, th, drop_hdrlen, tlen, iptos); 1405 return (IPPROTO_DONE); 1406 1407 dropwithreset: 1408 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1409 1410 if (inp != NULL) { 1411 tcp_dropwithreset(m, th, tp, tlen, rstreason); 1412 INP_UNLOCK(inp); 1413 } else 1414 tcp_dropwithreset(m, th, NULL, tlen, rstreason); 1415 m = NULL; /* mbuf chain got consumed. */ 1416 goto drop; 1417 1418 dropunlock: 1419 if (m != NULL) 1420 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1421 1422 if (inp != NULL) 1423 INP_UNLOCK(inp); 1424 1425 drop: 1426 if (s != NULL) 1427 free(s, M_TCPLOG); 1428 if (m != NULL) 1429 m_freem(m); 1430 return (IPPROTO_DONE); 1431 } 1432 1433 /* 1434 * Automatic sizing of receive socket buffer. Often the send 1435 * buffer size is not optimally adjusted to the actual network 1436 * conditions at hand (delay bandwidth product). Setting the 1437 * buffer size too small limits throughput on links with high 1438 * bandwidth and high delay (eg. trans-continental/oceanic links). 1439 * 1440 * On the receive side the socket buffer memory is only rarely 1441 * used to any significant extent. This allows us to be much 1442 * more aggressive in scaling the receive socket buffer. For 1443 * the case that the buffer space is actually used to a large 1444 * extent and we run out of kernel memory we can simply drop 1445 * the new segments; TCP on the sender will just retransmit it 1446 * later. Setting the buffer size too big may only consume too 1447 * much kernel memory if the application doesn't read() from 1448 * the socket or packet loss or reordering makes use of the 1449 * reassembly queue. 1450 * 1451 * The criteria to step up the receive buffer one notch are: 1452 * 1. Application has not set receive buffer size with 1453 * SO_RCVBUF. Setting SO_RCVBUF clears SB_AUTOSIZE. 1454 * 2. the number of bytes received during 1/2 of an sRTT 1455 * is at least 3/8 of the current socket buffer size. 1456 * 3. receive buffer size has not hit maximal automatic size; 1457 * 1458 * If all of the criteria are met we increaset the socket buffer 1459 * by a 1/2 (bounded by the max). This allows us to keep ahead 1460 * of slow-start but also makes it so our peer never gets limited 1461 * by our rwnd which we then open up causing a burst. 1462 * 1463 * This algorithm does two steps per RTT at most and only if 1464 * we receive a bulk stream w/o packet losses or reorderings. 1465 * Shrinking the buffer during idle times is not necessary as 1466 * it doesn't consume any memory when idle. 1467 * 1468 * TODO: Only step up if the application is actually serving 1469 * the buffer to better manage the socket buffer resources. 1470 */ 1471 int 1472 tcp_autorcvbuf(struct mbuf *m, struct tcphdr *th, struct socket *so, 1473 struct tcpcb *tp, int tlen) 1474 { 1475 int newsize = 0; 1476 1477 if (V_tcp_do_autorcvbuf && (so->so_rcv.sb_flags & SB_AUTOSIZE) && 1478 tp->t_srtt != 0 && tp->rfbuf_ts != 0 && 1479 TCP_TS_TO_TICKS(tcp_ts_getticks() - tp->rfbuf_ts) > 1480 ((tp->t_srtt >> TCP_RTT_SHIFT)/2)) { 1481 if (tp->rfbuf_cnt > ((so->so_rcv.sb_hiwat / 2)/ 4 * 3) && 1482 so->so_rcv.sb_hiwat < V_tcp_autorcvbuf_max) { 1483 newsize = min((so->so_rcv.sb_hiwat + (so->so_rcv.sb_hiwat/2)), V_tcp_autorcvbuf_max); 1484 } 1485 TCP_PROBE6(receive__autoresize, NULL, tp, m, tp, th, newsize); 1486 1487 /* Start over with next RTT. */ 1488 tp->rfbuf_ts = 0; 1489 tp->rfbuf_cnt = 0; 1490 } else { 1491 tp->rfbuf_cnt += tlen; /* add up */ 1492 } 1493 return (newsize); 1494 } 1495 1496 int 1497 tcp_input(struct mbuf **mp, int *offp, int proto) 1498 { 1499 return(tcp_input_with_port(mp, offp, proto, 0)); 1500 } 1501 1502 static void 1503 tcp_handle_wakeup(struct tcpcb *tp) 1504 { 1505 1506 INP_WLOCK_ASSERT(tptoinpcb(tp)); 1507 1508 if (tp->t_flags & TF_WAKESOR) { 1509 struct socket *so = tptosocket(tp); 1510 1511 tp->t_flags &= ~TF_WAKESOR; 1512 SOCKBUF_LOCK_ASSERT(&so->so_rcv); 1513 sorwakeup_locked(so); 1514 } 1515 } 1516 1517 void 1518 tcp_do_segment(struct tcpcb *tp, struct mbuf *m, struct tcphdr *th, 1519 int drop_hdrlen, int tlen, uint8_t iptos) 1520 { 1521 uint16_t thflags; 1522 int acked, ourfinisacked, needoutput = 0; 1523 sackstatus_t sack_changed; 1524 int rstreason, todrop, win, incforsyn = 0; 1525 uint32_t tiwin; 1526 uint16_t nsegs; 1527 char *s; 1528 struct inpcb *inp = tptoinpcb(tp); 1529 struct socket *so = tptosocket(tp); 1530 struct in_conninfo *inc = &inp->inp_inc; 1531 struct mbuf *mfree; 1532 struct tcpopt to; 1533 int tfo_syn; 1534 u_int maxseg; 1535 1536 thflags = tcp_get_flags(th); 1537 tp->sackhint.last_sack_ack = 0; 1538 sack_changed = SACK_NOCHANGE; 1539 nsegs = max(1, m->m_pkthdr.lro_nsegs); 1540 1541 NET_EPOCH_ASSERT(); 1542 INP_WLOCK_ASSERT(inp); 1543 KASSERT(tp->t_state > TCPS_LISTEN, ("%s: TCPS_LISTEN", 1544 __func__)); 1545 KASSERT(tp->t_state != TCPS_TIME_WAIT, ("%s: TCPS_TIME_WAIT", 1546 __func__)); 1547 1548 #ifdef TCPPCAP 1549 /* Save segment, if requested. */ 1550 tcp_pcap_add(th, m, &(tp->t_inpkts)); 1551 #endif 1552 TCP_LOG_EVENT(tp, th, &so->so_rcv, &so->so_snd, TCP_LOG_IN, 0, 1553 tlen, NULL, true); 1554 1555 if ((thflags & TH_SYN) && (thflags & TH_FIN) && V_drop_synfin) { 1556 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1557 log(LOG_DEBUG, "%s; %s: " 1558 "SYN|FIN segment ignored (based on " 1559 "sysctl setting)\n", s, __func__); 1560 free(s, M_TCPLOG); 1561 } 1562 goto drop; 1563 } 1564 1565 /* 1566 * If a segment with the ACK-bit set arrives in the SYN-SENT state 1567 * check SEQ.ACK first. 1568 */ 1569 if ((tp->t_state == TCPS_SYN_SENT) && (thflags & TH_ACK) && 1570 (SEQ_LEQ(th->th_ack, tp->iss) || SEQ_GT(th->th_ack, tp->snd_max))) { 1571 rstreason = BANDLIM_UNLIMITED; 1572 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 1573 goto dropwithreset; 1574 } 1575 1576 /* 1577 * Segment received on connection. 1578 * Reset idle time and keep-alive timer. 1579 * XXX: This should be done after segment 1580 * validation to ignore broken/spoofed segs. 1581 */ 1582 if (tp->t_idle_reduce && 1583 (tp->snd_max == tp->snd_una) && 1584 ((ticks - tp->t_rcvtime) >= tp->t_rxtcur)) 1585 cc_after_idle(tp); 1586 tp->t_rcvtime = ticks; 1587 1588 if (thflags & TH_FIN) 1589 tcp_log_end_status(tp, TCP_EI_STATUS_CLIENT_FIN); 1590 /* 1591 * Scale up the window into a 32-bit value. 1592 * For the SYN_SENT state the scale is zero. 1593 */ 1594 tiwin = th->th_win << tp->snd_scale; 1595 #ifdef STATS 1596 stats_voi_update_abs_ulong(tp->t_stats, VOI_TCP_FRWIN, tiwin); 1597 #endif 1598 1599 /* 1600 * TCP ECN processing. 1601 */ 1602 if (tcp_ecn_input_segment(tp, thflags, tlen, 1603 tcp_packets_this_ack(tp, th->th_ack), 1604 iptos)) 1605 cc_cong_signal(tp, th, CC_ECN); 1606 1607 /* 1608 * Parse options on any incoming segment. 1609 */ 1610 tcp_dooptions(&to, (u_char *)(th + 1), 1611 (th->th_off << 2) - sizeof(struct tcphdr), 1612 (thflags & TH_SYN) ? TO_SYN : 0); 1613 1614 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 1615 if ((tp->t_flags & TF_SIGNATURE) != 0 && 1616 (to.to_flags & TOF_SIGNATURE) == 0) { 1617 TCPSTAT_INC(tcps_sig_err_sigopt); 1618 /* XXX: should drop? */ 1619 } 1620 #endif 1621 /* 1622 * If echoed timestamp is later than the current time, 1623 * fall back to non RFC1323 RTT calculation. Normalize 1624 * timestamp if syncookies were used when this connection 1625 * was established. 1626 */ 1627 if ((to.to_flags & TOF_TS) && (to.to_tsecr != 0)) { 1628 to.to_tsecr -= tp->ts_offset; 1629 if (TSTMP_GT(to.to_tsecr, tcp_ts_getticks())) 1630 to.to_tsecr = 0; 1631 else if (tp->t_rxtshift == 1 && 1632 tp->t_flags & TF_PREVVALID && 1633 tp->t_badrxtwin != 0 && 1634 TSTMP_LT(to.to_tsecr, tp->t_badrxtwin)) 1635 cc_cong_signal(tp, th, CC_RTO_ERR); 1636 } 1637 /* 1638 * Process options only when we get SYN/ACK back. The SYN case 1639 * for incoming connections is handled in tcp_syncache. 1640 * According to RFC1323 the window field in a SYN (i.e., a <SYN> 1641 * or <SYN,ACK>) segment itself is never scaled. 1642 * XXX this is traditional behavior, may need to be cleaned up. 1643 */ 1644 if (tp->t_state == TCPS_SYN_SENT && (thflags & TH_SYN)) { 1645 /* Handle parallel SYN for ECN */ 1646 tcp_ecn_input_parallel_syn(tp, thflags, iptos); 1647 if ((to.to_flags & TOF_SCALE) && 1648 (tp->t_flags & TF_REQ_SCALE) && 1649 !(tp->t_flags & TF_NOOPT)) { 1650 tp->t_flags |= TF_RCVD_SCALE; 1651 tp->snd_scale = to.to_wscale; 1652 } else 1653 tp->t_flags &= ~TF_REQ_SCALE; 1654 /* 1655 * Initial send window. It will be updated with 1656 * the next incoming segment to the scaled value. 1657 */ 1658 tp->snd_wnd = th->th_win; 1659 if ((to.to_flags & TOF_TS) && 1660 (tp->t_flags & TF_REQ_TSTMP) && 1661 !(tp->t_flags & TF_NOOPT)) { 1662 tp->t_flags |= TF_RCVD_TSTMP; 1663 tp->ts_recent = to.to_tsval; 1664 tp->ts_recent_age = tcp_ts_getticks(); 1665 } else 1666 tp->t_flags &= ~TF_REQ_TSTMP; 1667 if (to.to_flags & TOF_MSS) 1668 tcp_mss(tp, to.to_mss); 1669 if ((tp->t_flags & TF_SACK_PERMIT) && 1670 (!(to.to_flags & TOF_SACKPERM) || 1671 (tp->t_flags & TF_NOOPT))) 1672 tp->t_flags &= ~TF_SACK_PERMIT; 1673 if (IS_FASTOPEN(tp->t_flags)) { 1674 if ((to.to_flags & TOF_FASTOPEN) && 1675 !(tp->t_flags & TF_NOOPT)) { 1676 uint16_t mss; 1677 1678 if (to.to_flags & TOF_MSS) 1679 mss = to.to_mss; 1680 else 1681 if ((inp->inp_vflag & INP_IPV6) != 0) 1682 mss = TCP6_MSS; 1683 else 1684 mss = TCP_MSS; 1685 tcp_fastopen_update_cache(tp, mss, 1686 to.to_tfo_len, to.to_tfo_cookie); 1687 } else 1688 tcp_fastopen_disable_path(tp); 1689 } 1690 } 1691 1692 /* 1693 * If timestamps were negotiated during SYN/ACK and a 1694 * segment without a timestamp is received, silently drop 1695 * the segment, unless it is a RST segment or missing timestamps are 1696 * tolerated. 1697 * See section 3.2 of RFC 7323. 1698 */ 1699 if ((tp->t_flags & TF_RCVD_TSTMP) && !(to.to_flags & TOF_TS)) { 1700 if (((thflags & TH_RST) != 0) || V_tcp_tolerate_missing_ts) { 1701 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1702 log(LOG_DEBUG, "%s; %s: Timestamp missing, " 1703 "segment processed normally\n", 1704 s, __func__); 1705 free(s, M_TCPLOG); 1706 } 1707 } else { 1708 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1709 log(LOG_DEBUG, "%s; %s: Timestamp missing, " 1710 "segment silently dropped\n", s, __func__); 1711 free(s, M_TCPLOG); 1712 } 1713 goto drop; 1714 } 1715 } 1716 /* 1717 * If timestamps were not negotiated during SYN/ACK and a 1718 * segment with a timestamp is received, ignore the 1719 * timestamp and process the packet normally. 1720 * See section 3.2 of RFC 7323. 1721 */ 1722 if (!(tp->t_flags & TF_RCVD_TSTMP) && (to.to_flags & TOF_TS)) { 1723 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1724 log(LOG_DEBUG, "%s; %s: Timestamp not expected, " 1725 "segment processed normally\n", s, __func__); 1726 free(s, M_TCPLOG); 1727 } 1728 } 1729 1730 /* 1731 * Header prediction: check for the two common cases 1732 * of a uni-directional data xfer. If the packet has 1733 * no control flags, is in-sequence, the window didn't 1734 * change and we're not retransmitting, it's a 1735 * candidate. If the length is zero and the ack moved 1736 * forward, we're the sender side of the xfer. Just 1737 * free the data acked & wake any higher level process 1738 * that was blocked waiting for space. If the length 1739 * is non-zero and the ack didn't move, we're the 1740 * receiver side. If we're getting packets in-order 1741 * (the reassembly queue is empty), add the data to 1742 * the socket buffer and note that we need a delayed ack. 1743 * Make sure that the hidden state-flags are also off. 1744 * Since we check for TCPS_ESTABLISHED first, it can only 1745 * be TH_NEEDSYN. 1746 */ 1747 if (tp->t_state == TCPS_ESTABLISHED && 1748 th->th_seq == tp->rcv_nxt && 1749 (thflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK && 1750 tp->snd_nxt == tp->snd_max && 1751 tiwin && tiwin == tp->snd_wnd && 1752 ((tp->t_flags & (TF_NEEDSYN|TF_NEEDFIN)) == 0) && 1753 SEGQ_EMPTY(tp) && 1754 ((to.to_flags & TOF_TS) == 0 || 1755 TSTMP_GEQ(to.to_tsval, tp->ts_recent)) ) { 1756 /* 1757 * If last ACK falls within this segment's sequence numbers, 1758 * record the timestamp. 1759 * NOTE that the test is modified according to the latest 1760 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 1761 */ 1762 if ((to.to_flags & TOF_TS) != 0 && 1763 SEQ_LEQ(th->th_seq, tp->last_ack_sent)) { 1764 tp->ts_recent_age = tcp_ts_getticks(); 1765 tp->ts_recent = to.to_tsval; 1766 } 1767 1768 if (tlen == 0) { 1769 if (SEQ_GT(th->th_ack, tp->snd_una) && 1770 SEQ_LEQ(th->th_ack, tp->snd_max) && 1771 !IN_RECOVERY(tp->t_flags) && 1772 (to.to_flags & TOF_SACK) == 0 && 1773 TAILQ_EMPTY(&tp->snd_holes)) { 1774 /* 1775 * This is a pure ack for outstanding data. 1776 */ 1777 TCPSTAT_INC(tcps_predack); 1778 1779 /* 1780 * "bad retransmit" recovery without timestamps. 1781 */ 1782 if ((to.to_flags & TOF_TS) == 0 && 1783 tp->t_rxtshift == 1 && 1784 tp->t_flags & TF_PREVVALID && 1785 tp->t_badrxtwin != 0 && 1786 TSTMP_LT(ticks, tp->t_badrxtwin)) { 1787 cc_cong_signal(tp, th, CC_RTO_ERR); 1788 } 1789 1790 /* 1791 * Recalculate the transmit timer / rtt. 1792 * 1793 * Some boxes send broken timestamp replies 1794 * during the SYN+ACK phase, ignore 1795 * timestamps of 0 or we could calculate a 1796 * huge RTT and blow up the retransmit timer. 1797 */ 1798 if ((to.to_flags & TOF_TS) != 0 && 1799 to.to_tsecr) { 1800 uint32_t t; 1801 1802 t = tcp_ts_getticks() - to.to_tsecr; 1803 if (!tp->t_rttlow || tp->t_rttlow > t) 1804 tp->t_rttlow = t; 1805 tcp_xmit_timer(tp, 1806 TCP_TS_TO_TICKS(t) + 1); 1807 } else if (tp->t_rtttime && 1808 SEQ_GT(th->th_ack, tp->t_rtseq)) { 1809 if (!tp->t_rttlow || 1810 tp->t_rttlow > ticks - tp->t_rtttime) 1811 tp->t_rttlow = ticks - tp->t_rtttime; 1812 tcp_xmit_timer(tp, 1813 ticks - tp->t_rtttime); 1814 } 1815 acked = BYTES_THIS_ACK(tp, th); 1816 1817 #ifdef TCP_HHOOK 1818 /* Run HHOOK_TCP_ESTABLISHED_IN helper hooks. */ 1819 hhook_run_tcp_est_in(tp, th, &to); 1820 #endif 1821 1822 TCPSTAT_ADD(tcps_rcvackpack, nsegs); 1823 TCPSTAT_ADD(tcps_rcvackbyte, acked); 1824 sbdrop(&so->so_snd, acked); 1825 if (SEQ_GT(tp->snd_una, tp->snd_recover) && 1826 SEQ_LEQ(th->th_ack, tp->snd_recover)) 1827 tp->snd_recover = th->th_ack - 1; 1828 1829 /* 1830 * Let the congestion control algorithm update 1831 * congestion control related information. This 1832 * typically means increasing the congestion 1833 * window. 1834 */ 1835 cc_ack_received(tp, th, nsegs, CC_ACK); 1836 1837 tp->snd_una = th->th_ack; 1838 /* 1839 * Pull snd_wl2 up to prevent seq wrap relative 1840 * to th_ack. 1841 */ 1842 tp->snd_wl2 = th->th_ack; 1843 tp->t_dupacks = 0; 1844 m_freem(m); 1845 1846 /* 1847 * If all outstanding data are acked, stop 1848 * retransmit timer, otherwise restart timer 1849 * using current (possibly backed-off) value. 1850 * If process is waiting for space, 1851 * wakeup/selwakeup/signal. If data 1852 * are ready to send, let tcp_output 1853 * decide between more output or persist. 1854 */ 1855 TCP_PROBE3(debug__input, tp, th, m); 1856 /* 1857 * Clear t_acktime if remote side has ACKd 1858 * all data in the socket buffer. 1859 * Otherwise, update t_acktime if we received 1860 * a sufficiently large ACK. 1861 */ 1862 if (sbavail(&so->so_snd) == 0) 1863 tp->t_acktime = 0; 1864 else if (acked > 1) 1865 tp->t_acktime = ticks; 1866 if (tp->snd_una == tp->snd_max) 1867 tcp_timer_activate(tp, TT_REXMT, 0); 1868 else if (!tcp_timer_active(tp, TT_PERSIST)) 1869 tcp_timer_activate(tp, TT_REXMT, 1870 TP_RXTCUR(tp)); 1871 sowwakeup(so); 1872 if (sbavail(&so->so_snd)) 1873 (void) tcp_output(tp); 1874 goto check_delack; 1875 } 1876 } else if (th->th_ack == tp->snd_una && 1877 tlen <= sbspace(&so->so_rcv)) { 1878 int newsize = 0; /* automatic sockbuf scaling */ 1879 1880 /* 1881 * This is a pure, in-sequence data packet with 1882 * nothing on the reassembly queue and we have enough 1883 * buffer space to take it. 1884 */ 1885 /* Clean receiver SACK report if present */ 1886 if ((tp->t_flags & TF_SACK_PERMIT) && tp->rcv_numsacks) 1887 tcp_clean_sackreport(tp); 1888 TCPSTAT_INC(tcps_preddat); 1889 tp->rcv_nxt += tlen; 1890 if (tlen && 1891 ((tp->t_flags2 & TF2_FBYTES_COMPLETE) == 0) && 1892 (tp->t_fbyte_in == 0)) { 1893 tp->t_fbyte_in = ticks; 1894 if (tp->t_fbyte_in == 0) 1895 tp->t_fbyte_in = 1; 1896 if (tp->t_fbyte_out && tp->t_fbyte_in) 1897 tp->t_flags2 |= TF2_FBYTES_COMPLETE; 1898 } 1899 /* 1900 * Pull snd_wl1 up to prevent seq wrap relative to 1901 * th_seq. 1902 */ 1903 tp->snd_wl1 = th->th_seq; 1904 /* 1905 * Pull rcv_up up to prevent seq wrap relative to 1906 * rcv_nxt. 1907 */ 1908 tp->rcv_up = tp->rcv_nxt; 1909 TCPSTAT_ADD(tcps_rcvpack, nsegs); 1910 TCPSTAT_ADD(tcps_rcvbyte, tlen); 1911 TCP_PROBE3(debug__input, tp, th, m); 1912 1913 newsize = tcp_autorcvbuf(m, th, so, tp, tlen); 1914 1915 /* Add data to socket buffer. */ 1916 SOCKBUF_LOCK(&so->so_rcv); 1917 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 1918 m_freem(m); 1919 } else { 1920 /* 1921 * Set new socket buffer size. 1922 * Give up when limit is reached. 1923 */ 1924 if (newsize) 1925 if (!sbreserve_locked(so, SO_RCV, 1926 newsize, NULL)) 1927 so->so_rcv.sb_flags &= ~SB_AUTOSIZE; 1928 m_adj(m, drop_hdrlen); /* delayed header drop */ 1929 sbappendstream_locked(&so->so_rcv, m, 0); 1930 } 1931 /* NB: sorwakeup_locked() does an implicit unlock. */ 1932 sorwakeup_locked(so); 1933 if (DELAY_ACK(tp, tlen)) { 1934 tp->t_flags |= TF_DELACK; 1935 } else { 1936 tp->t_flags |= TF_ACKNOW; 1937 tcp_output(tp); 1938 } 1939 goto check_delack; 1940 } 1941 } 1942 1943 /* 1944 * Calculate amount of space in receive window, 1945 * and then do TCP input processing. 1946 * Receive window is amount of space in rcv queue, 1947 * but not less than advertised window. 1948 */ 1949 win = sbspace(&so->so_rcv); 1950 if (win < 0) 1951 win = 0; 1952 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 1953 1954 switch (tp->t_state) { 1955 /* 1956 * If the state is SYN_RECEIVED: 1957 * if seg contains an ACK, but not for our SYN/ACK, send a RST. 1958 */ 1959 case TCPS_SYN_RECEIVED: 1960 if (thflags & TH_RST) { 1961 /* Handle RST segments later. */ 1962 break; 1963 } 1964 if ((thflags & TH_ACK) && 1965 (SEQ_LEQ(th->th_ack, tp->snd_una) || 1966 SEQ_GT(th->th_ack, tp->snd_max))) { 1967 rstreason = BANDLIM_RST_OPENPORT; 1968 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 1969 goto dropwithreset; 1970 } 1971 if (IS_FASTOPEN(tp->t_flags)) { 1972 /* 1973 * When a TFO connection is in SYN_RECEIVED, the 1974 * only valid packets are the initial SYN, a 1975 * retransmit/copy of the initial SYN (possibly with 1976 * a subset of the original data), a valid ACK, a 1977 * FIN, or a RST. 1978 */ 1979 if ((thflags & (TH_SYN|TH_ACK)) == (TH_SYN|TH_ACK)) { 1980 rstreason = BANDLIM_RST_OPENPORT; 1981 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 1982 goto dropwithreset; 1983 } else if (thflags & TH_SYN) { 1984 /* non-initial SYN is ignored */ 1985 if ((tcp_timer_active(tp, TT_DELACK) || 1986 tcp_timer_active(tp, TT_REXMT))) 1987 goto drop; 1988 } else if (!(thflags & (TH_ACK|TH_FIN|TH_RST))) { 1989 goto drop; 1990 } 1991 } 1992 break; 1993 1994 /* 1995 * If the state is SYN_SENT: 1996 * if seg contains a RST with valid ACK (SEQ.ACK has already 1997 * been verified), then drop the connection. 1998 * if seg contains a RST without an ACK, drop the seg. 1999 * if seg does not contain SYN, then drop the seg. 2000 * Otherwise this is an acceptable SYN segment 2001 * initialize tp->rcv_nxt and tp->irs 2002 * if seg contains ack then advance tp->snd_una 2003 * if seg contains an ECE and ECN support is enabled, the stream 2004 * is ECN capable. 2005 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 2006 * arrange for segment to be acked (eventually) 2007 * continue processing rest of data/controls, beginning with URG 2008 */ 2009 case TCPS_SYN_SENT: 2010 if ((thflags & (TH_ACK|TH_RST)) == (TH_ACK|TH_RST)) { 2011 TCP_PROBE5(connect__refused, NULL, tp, 2012 m, tp, th); 2013 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 2014 tp = tcp_drop(tp, ECONNREFUSED); 2015 } 2016 if (thflags & TH_RST) 2017 goto drop; 2018 if (!(thflags & TH_SYN)) 2019 goto drop; 2020 2021 tp->irs = th->th_seq; 2022 tcp_rcvseqinit(tp); 2023 if (thflags & TH_ACK) { 2024 int tfo_partial_ack = 0; 2025 2026 TCPSTAT_INC(tcps_connects); 2027 soisconnected(so); 2028 #ifdef MAC 2029 mac_socketpeer_set_from_mbuf(m, so); 2030 #endif 2031 /* Do window scaling on this connection? */ 2032 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2033 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2034 tp->rcv_scale = tp->request_r_scale; 2035 } 2036 tp->rcv_adv += min(tp->rcv_wnd, 2037 TCP_MAXWIN << tp->rcv_scale); 2038 tp->snd_una++; /* SYN is acked */ 2039 /* 2040 * If not all the data that was sent in the TFO SYN 2041 * has been acked, resend the remainder right away. 2042 */ 2043 if (IS_FASTOPEN(tp->t_flags) && 2044 (tp->snd_una != tp->snd_max)) { 2045 tp->snd_nxt = th->th_ack; 2046 tfo_partial_ack = 1; 2047 } 2048 /* 2049 * If there's data, delay ACK; if there's also a FIN 2050 * ACKNOW will be turned on later. 2051 */ 2052 if (DELAY_ACK(tp, tlen) && tlen != 0 && !tfo_partial_ack) 2053 tcp_timer_activate(tp, TT_DELACK, 2054 tcp_delacktime); 2055 else 2056 tp->t_flags |= TF_ACKNOW; 2057 2058 tcp_ecn_input_syn_sent(tp, thflags, iptos); 2059 2060 /* 2061 * Received <SYN,ACK> in SYN_SENT[*] state. 2062 * Transitions: 2063 * SYN_SENT --> ESTABLISHED 2064 * SYN_SENT* --> FIN_WAIT_1 2065 */ 2066 tp->t_starttime = ticks; 2067 if (tp->t_flags & TF_NEEDFIN) { 2068 tp->t_acktime = ticks; 2069 tcp_state_change(tp, TCPS_FIN_WAIT_1); 2070 tp->t_flags &= ~TF_NEEDFIN; 2071 thflags &= ~TH_SYN; 2072 } else { 2073 tcp_state_change(tp, TCPS_ESTABLISHED); 2074 TCP_PROBE5(connect__established, NULL, tp, 2075 m, tp, th); 2076 cc_conn_init(tp); 2077 tcp_timer_activate(tp, TT_KEEP, 2078 TP_KEEPIDLE(tp)); 2079 } 2080 } else { 2081 /* 2082 * Received initial SYN in SYN-SENT[*] state => 2083 * simultaneous open. 2084 * If it succeeds, connection is * half-synchronized. 2085 * Otherwise, do 3-way handshake: 2086 * SYN-SENT -> SYN-RECEIVED 2087 * SYN-SENT* -> SYN-RECEIVED* 2088 */ 2089 tp->t_flags |= (TF_ACKNOW | TF_NEEDSYN | TF_SONOTCONN); 2090 tcp_timer_activate(tp, TT_REXMT, 0); 2091 tcp_state_change(tp, TCPS_SYN_RECEIVED); 2092 } 2093 2094 /* 2095 * Advance th->th_seq to correspond to first data byte. 2096 * If data, trim to stay within window, 2097 * dropping FIN if necessary. 2098 */ 2099 th->th_seq++; 2100 if (tlen > tp->rcv_wnd) { 2101 todrop = tlen - tp->rcv_wnd; 2102 m_adj(m, -todrop); 2103 tlen = tp->rcv_wnd; 2104 thflags &= ~TH_FIN; 2105 TCPSTAT_INC(tcps_rcvpackafterwin); 2106 TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); 2107 } 2108 tp->snd_wl1 = th->th_seq - 1; 2109 tp->rcv_up = th->th_seq; 2110 /* 2111 * Client side of transaction: already sent SYN and data. 2112 * If the remote host used T/TCP to validate the SYN, 2113 * our data will be ACK'd; if so, enter normal data segment 2114 * processing in the middle of step 5, ack processing. 2115 * Otherwise, goto step 6. 2116 */ 2117 if (thflags & TH_ACK) 2118 goto process_ACK; 2119 2120 goto step6; 2121 } 2122 2123 /* 2124 * States other than LISTEN or SYN_SENT. 2125 * First check the RST flag and sequence number since reset segments 2126 * are exempt from the timestamp and connection count tests. This 2127 * fixes a bug introduced by the Stevens, vol. 2, p. 960 bugfix 2128 * below which allowed reset segments in half the sequence space 2129 * to fall though and be processed (which gives forged reset 2130 * segments with a random sequence number a 50 percent chance of 2131 * killing a connection). 2132 * Then check timestamp, if present. 2133 * Then check the connection count, if present. 2134 * Then check that at least some bytes of segment are within 2135 * receive window. If segment begins before rcv_nxt, 2136 * drop leading data (and SYN); if nothing left, just ack. 2137 */ 2138 if (thflags & TH_RST) { 2139 /* 2140 * RFC5961 Section 3.2 2141 * 2142 * - RST drops connection only if SEG.SEQ == RCV.NXT. 2143 * - If RST is in window, we send challenge ACK. 2144 * 2145 * Note: to take into account delayed ACKs, we should 2146 * test against last_ack_sent instead of rcv_nxt. 2147 * Note 2: we handle special case of closed window, not 2148 * covered by the RFC. 2149 */ 2150 if ((SEQ_GEQ(th->th_seq, tp->last_ack_sent) && 2151 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) || 2152 (tp->rcv_wnd == 0 && tp->last_ack_sent == th->th_seq)) { 2153 KASSERT(tp->t_state != TCPS_SYN_SENT, 2154 ("%s: TH_RST for TCPS_SYN_SENT th %p tp %p", 2155 __func__, th, tp)); 2156 2157 if (V_tcp_insecure_rst || 2158 tp->last_ack_sent == th->th_seq) { 2159 TCPSTAT_INC(tcps_drops); 2160 /* Drop the connection. */ 2161 switch (tp->t_state) { 2162 case TCPS_SYN_RECEIVED: 2163 so->so_error = ECONNREFUSED; 2164 goto close; 2165 case TCPS_ESTABLISHED: 2166 case TCPS_FIN_WAIT_1: 2167 case TCPS_FIN_WAIT_2: 2168 case TCPS_CLOSE_WAIT: 2169 case TCPS_CLOSING: 2170 case TCPS_LAST_ACK: 2171 so->so_error = ECONNRESET; 2172 close: 2173 /* FALLTHROUGH */ 2174 default: 2175 tcp_log_end_status(tp, TCP_EI_STATUS_CLIENT_RST); 2176 tp = tcp_close(tp); 2177 } 2178 } else { 2179 TCPSTAT_INC(tcps_badrst); 2180 /* Send challenge ACK. */ 2181 tcp_respond(tp, mtod(m, void *), th, m, 2182 tp->rcv_nxt, tp->snd_nxt, TH_ACK); 2183 tp->last_ack_sent = tp->rcv_nxt; 2184 m = NULL; 2185 } 2186 } 2187 goto drop; 2188 } 2189 2190 /* 2191 * RFC5961 Section 4.2 2192 * Send challenge ACK for any SYN in synchronized state. 2193 */ 2194 if ((thflags & TH_SYN) && tp->t_state != TCPS_SYN_SENT && 2195 tp->t_state != TCPS_SYN_RECEIVED) { 2196 TCPSTAT_INC(tcps_badsyn); 2197 if (V_tcp_insecure_syn && 2198 SEQ_GEQ(th->th_seq, tp->last_ack_sent) && 2199 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) { 2200 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 2201 tp = tcp_drop(tp, ECONNRESET); 2202 rstreason = BANDLIM_UNLIMITED; 2203 } else { 2204 tcp_ecn_input_syn_sent(tp, thflags, iptos); 2205 /* Send challenge ACK. */ 2206 tcp_respond(tp, mtod(m, void *), th, m, tp->rcv_nxt, 2207 tp->snd_nxt, TH_ACK); 2208 tp->last_ack_sent = tp->rcv_nxt; 2209 m = NULL; 2210 } 2211 goto drop; 2212 } 2213 2214 /* 2215 * RFC 1323 PAWS: If we have a timestamp reply on this segment 2216 * and it's less than ts_recent, drop it. 2217 */ 2218 if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent && 2219 TSTMP_LT(to.to_tsval, tp->ts_recent)) { 2220 /* Check to see if ts_recent is over 24 days old. */ 2221 if (tcp_ts_getticks() - tp->ts_recent_age > TCP_PAWS_IDLE) { 2222 /* 2223 * Invalidate ts_recent. If this segment updates 2224 * ts_recent, the age will be reset later and ts_recent 2225 * will get a valid value. If it does not, setting 2226 * ts_recent to zero will at least satisfy the 2227 * requirement that zero be placed in the timestamp 2228 * echo reply when ts_recent isn't valid. The 2229 * age isn't reset until we get a valid ts_recent 2230 * because we don't want out-of-order segments to be 2231 * dropped when ts_recent is old. 2232 */ 2233 tp->ts_recent = 0; 2234 } else { 2235 TCPSTAT_INC(tcps_rcvduppack); 2236 TCPSTAT_ADD(tcps_rcvdupbyte, tlen); 2237 TCPSTAT_INC(tcps_pawsdrop); 2238 if (tlen) 2239 goto dropafterack; 2240 goto drop; 2241 } 2242 } 2243 2244 /* 2245 * In the SYN-RECEIVED state, validate that the packet belongs to 2246 * this connection before trimming the data to fit the receive 2247 * window. Check the sequence number versus IRS since we know 2248 * the sequence numbers haven't wrapped. This is a partial fix 2249 * for the "LAND" DoS attack. 2250 */ 2251 if (tp->t_state == TCPS_SYN_RECEIVED && SEQ_LT(th->th_seq, tp->irs)) { 2252 rstreason = BANDLIM_RST_OPENPORT; 2253 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 2254 goto dropwithreset; 2255 } 2256 2257 todrop = tp->rcv_nxt - th->th_seq; 2258 if (todrop > 0) { 2259 if (thflags & TH_SYN) { 2260 thflags &= ~TH_SYN; 2261 th->th_seq++; 2262 if (th->th_urp > 1) 2263 th->th_urp--; 2264 else 2265 thflags &= ~TH_URG; 2266 todrop--; 2267 } 2268 /* 2269 * Following if statement from Stevens, vol. 2, p. 960. 2270 */ 2271 if (todrop > tlen 2272 || (todrop == tlen && (thflags & TH_FIN) == 0)) { 2273 /* 2274 * Any valid FIN must be to the left of the window. 2275 * At this point the FIN must be a duplicate or out 2276 * of sequence; drop it. 2277 */ 2278 thflags &= ~TH_FIN; 2279 2280 /* 2281 * Send an ACK to resynchronize and drop any data. 2282 * But keep on processing for RST or ACK. 2283 */ 2284 tp->t_flags |= TF_ACKNOW; 2285 todrop = tlen; 2286 TCPSTAT_INC(tcps_rcvduppack); 2287 TCPSTAT_ADD(tcps_rcvdupbyte, todrop); 2288 } else { 2289 TCPSTAT_INC(tcps_rcvpartduppack); 2290 TCPSTAT_ADD(tcps_rcvpartdupbyte, todrop); 2291 } 2292 /* 2293 * DSACK - add SACK block for dropped range 2294 */ 2295 if ((todrop > 0) && (tp->t_flags & TF_SACK_PERMIT)) { 2296 tcp_update_sack_list(tp, th->th_seq, 2297 th->th_seq + todrop); 2298 /* 2299 * ACK now, as the next in-sequence segment 2300 * will clear the DSACK block again 2301 */ 2302 tp->t_flags |= TF_ACKNOW; 2303 } 2304 drop_hdrlen += todrop; /* drop from the top afterwards */ 2305 th->th_seq += todrop; 2306 tlen -= todrop; 2307 if (th->th_urp > todrop) 2308 th->th_urp -= todrop; 2309 else { 2310 thflags &= ~TH_URG; 2311 th->th_urp = 0; 2312 } 2313 } 2314 2315 /* 2316 * If new data are received on a connection after the 2317 * user processes are gone, then RST the other end. 2318 */ 2319 if ((tp->t_flags & TF_CLOSED) && tlen) { 2320 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 2321 log(LOG_DEBUG, "%s; %s: %s: Received %d bytes of data " 2322 "after socket was closed, " 2323 "sending RST and removing tcpcb\n", 2324 s, __func__, tcpstates[tp->t_state], tlen); 2325 free(s, M_TCPLOG); 2326 } 2327 tcp_log_end_status(tp, TCP_EI_STATUS_DATA_A_CLOSE); 2328 /* tcp_close will kill the inp pre-log the Reset */ 2329 tcp_log_end_status(tp, TCP_EI_STATUS_SERVER_RST); 2330 tp = tcp_close(tp); 2331 TCPSTAT_INC(tcps_rcvafterclose); 2332 rstreason = BANDLIM_UNLIMITED; 2333 goto dropwithreset; 2334 } 2335 2336 /* 2337 * If segment ends after window, drop trailing data 2338 * (and PUSH and FIN); if nothing left, just ACK. 2339 */ 2340 todrop = (th->th_seq + tlen) - (tp->rcv_nxt + tp->rcv_wnd); 2341 if (todrop > 0) { 2342 TCPSTAT_INC(tcps_rcvpackafterwin); 2343 if (todrop >= tlen) { 2344 TCPSTAT_ADD(tcps_rcvbyteafterwin, tlen); 2345 /* 2346 * If window is closed can only take segments at 2347 * window edge, and have to drop data and PUSH from 2348 * incoming segments. Continue processing, but 2349 * remember to ack. Otherwise, drop segment 2350 * and ack. 2351 */ 2352 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 2353 tp->t_flags |= TF_ACKNOW; 2354 TCPSTAT_INC(tcps_rcvwinprobe); 2355 } else 2356 goto dropafterack; 2357 } else 2358 TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); 2359 m_adj(m, -todrop); 2360 tlen -= todrop; 2361 thflags &= ~(TH_PUSH|TH_FIN); 2362 } 2363 2364 /* 2365 * If last ACK falls within this segment's sequence numbers, 2366 * record its timestamp. 2367 * NOTE: 2368 * 1) That the test incorporates suggestions from the latest 2369 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 2370 * 2) That updating only on newer timestamps interferes with 2371 * our earlier PAWS tests, so this check should be solely 2372 * predicated on the sequence space of this segment. 2373 * 3) That we modify the segment boundary check to be 2374 * Last.ACK.Sent <= SEG.SEQ + SEG.Len 2375 * instead of RFC1323's 2376 * Last.ACK.Sent < SEG.SEQ + SEG.Len, 2377 * This modified check allows us to overcome RFC1323's 2378 * limitations as described in Stevens TCP/IP Illustrated 2379 * Vol. 2 p.869. In such cases, we can still calculate the 2380 * RTT correctly when RCV.NXT == Last.ACK.Sent. 2381 */ 2382 if ((to.to_flags & TOF_TS) != 0 && 2383 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 2384 SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen + 2385 ((thflags & (TH_SYN|TH_FIN)) != 0))) { 2386 tp->ts_recent_age = tcp_ts_getticks(); 2387 tp->ts_recent = to.to_tsval; 2388 } 2389 2390 /* 2391 * If the ACK bit is off: if in SYN-RECEIVED state or SENDSYN 2392 * flag is on (half-synchronized state), then queue data for 2393 * later processing; else drop segment and return. 2394 */ 2395 if ((thflags & TH_ACK) == 0) { 2396 if (tp->t_state == TCPS_SYN_RECEIVED || 2397 (tp->t_flags & TF_NEEDSYN)) { 2398 if (tp->t_state == TCPS_SYN_RECEIVED && 2399 IS_FASTOPEN(tp->t_flags)) { 2400 tp->snd_wnd = tiwin; 2401 cc_conn_init(tp); 2402 } 2403 goto step6; 2404 } else if (tp->t_flags & TF_ACKNOW) 2405 goto dropafterack; 2406 else 2407 goto drop; 2408 } 2409 2410 /* 2411 * Ack processing. 2412 */ 2413 switch (tp->t_state) { 2414 /* 2415 * In SYN_RECEIVED state, the ack ACKs our SYN, so enter 2416 * ESTABLISHED state and continue processing. 2417 * The ACK was checked above. 2418 */ 2419 case TCPS_SYN_RECEIVED: 2420 2421 TCPSTAT_INC(tcps_connects); 2422 if (tp->t_flags & TF_SONOTCONN) { 2423 /* 2424 * Usually SYN_RECEIVED had been created from a LISTEN, 2425 * and solisten_enqueue() has already marked the socket 2426 * layer as connected. If it didn't, which can happen 2427 * only with an accept_filter(9), then the tp is marked 2428 * with TF_SONOTCONN. The other reason for this mark 2429 * to be set is a simultaneous open, a SYN_RECEIVED 2430 * that had been created from SYN_SENT. 2431 */ 2432 tp->t_flags &= ~TF_SONOTCONN; 2433 soisconnected(so); 2434 } 2435 /* Do window scaling? */ 2436 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2437 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2438 tp->rcv_scale = tp->request_r_scale; 2439 } 2440 tp->snd_wnd = tiwin; 2441 /* 2442 * Make transitions: 2443 * SYN-RECEIVED -> ESTABLISHED 2444 * SYN-RECEIVED* -> FIN-WAIT-1 2445 */ 2446 tp->t_starttime = ticks; 2447 if (IS_FASTOPEN(tp->t_flags) && tp->t_tfo_pending) { 2448 tcp_fastopen_decrement_counter(tp->t_tfo_pending); 2449 tp->t_tfo_pending = NULL; 2450 } 2451 if (tp->t_flags & TF_NEEDFIN) { 2452 tp->t_acktime = ticks; 2453 tcp_state_change(tp, TCPS_FIN_WAIT_1); 2454 tp->t_flags &= ~TF_NEEDFIN; 2455 } else { 2456 tcp_state_change(tp, TCPS_ESTABLISHED); 2457 TCP_PROBE5(accept__established, NULL, tp, 2458 m, tp, th); 2459 /* 2460 * TFO connections call cc_conn_init() during SYN 2461 * processing. Calling it again here for such 2462 * connections is not harmless as it would undo the 2463 * snd_cwnd reduction that occurs when a TFO SYN|ACK 2464 * is retransmitted. 2465 */ 2466 if (!IS_FASTOPEN(tp->t_flags)) 2467 cc_conn_init(tp); 2468 tcp_timer_activate(tp, TT_KEEP, TP_KEEPIDLE(tp)); 2469 } 2470 /* 2471 * Account for the ACK of our SYN prior to 2472 * regular ACK processing below, except for 2473 * simultaneous SYN, which is handled later. 2474 */ 2475 if (SEQ_GT(th->th_ack, tp->snd_una) && !(tp->t_flags & TF_NEEDSYN)) 2476 incforsyn = 1; 2477 /* 2478 * If segment contains data or ACK, will call tcp_reass() 2479 * later; if not, do so now to pass queued data to user. 2480 */ 2481 if (tlen == 0 && (thflags & TH_FIN) == 0) { 2482 (void) tcp_reass(tp, (struct tcphdr *)0, NULL, 0, 2483 (struct mbuf *)0); 2484 tcp_handle_wakeup(tp); 2485 } 2486 tp->snd_wl1 = th->th_seq - 1; 2487 /* FALLTHROUGH */ 2488 2489 /* 2490 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 2491 * ACKs. If the ack is in the range 2492 * tp->snd_una < th->th_ack <= tp->snd_max 2493 * then advance tp->snd_una to th->th_ack and drop 2494 * data from the retransmission queue. If this ACK reflects 2495 * more up to date window information we update our window information. 2496 */ 2497 case TCPS_ESTABLISHED: 2498 case TCPS_FIN_WAIT_1: 2499 case TCPS_FIN_WAIT_2: 2500 case TCPS_CLOSE_WAIT: 2501 case TCPS_CLOSING: 2502 case TCPS_LAST_ACK: 2503 if (SEQ_GT(th->th_ack, tp->snd_max)) { 2504 TCPSTAT_INC(tcps_rcvacktoomuch); 2505 goto dropafterack; 2506 } 2507 if (tcp_is_sack_recovery(tp, &to)) { 2508 if (((sack_changed = tcp_sack_doack(tp, &to, th->th_ack)) != 0) && 2509 (tp->t_flags & TF_LRD)) { 2510 tcp_sack_lost_retransmission(tp, th); 2511 } 2512 } else 2513 /* 2514 * Reset the value so that previous (valid) value 2515 * from the last ack with SACK doesn't get used. 2516 */ 2517 tp->sackhint.sacked_bytes = 0; 2518 2519 #ifdef TCP_HHOOK 2520 /* Run HHOOK_TCP_ESTABLISHED_IN helper hooks. */ 2521 hhook_run_tcp_est_in(tp, th, &to); 2522 #endif 2523 2524 if (SEQ_LEQ(th->th_ack, tp->snd_una)) { 2525 maxseg = tcp_maxseg(tp); 2526 if (tlen == 0 && 2527 (tiwin == tp->snd_wnd || 2528 (tp->t_flags & TF_SACK_PERMIT))) { 2529 /* 2530 * If this is the first time we've seen a 2531 * FIN from the remote, this is not a 2532 * duplicate and it needs to be processed 2533 * normally. This happens during a 2534 * simultaneous close. 2535 */ 2536 if ((thflags & TH_FIN) && 2537 (TCPS_HAVERCVDFIN(tp->t_state) == 0)) { 2538 tp->t_dupacks = 0; 2539 break; 2540 } 2541 TCPSTAT_INC(tcps_rcvdupack); 2542 /* 2543 * If we have outstanding data (other than 2544 * a window probe), this is a completely 2545 * duplicate ack (ie, window info didn't 2546 * change and FIN isn't set), 2547 * the ack is the biggest we've 2548 * seen and we've seen exactly our rexmt 2549 * threshold of them, assume a packet 2550 * has been dropped and retransmit it. 2551 * Kludge snd_nxt & the congestion 2552 * window so we send only this one 2553 * packet. 2554 * 2555 * We know we're losing at the current 2556 * window size so do congestion avoidance 2557 * (set ssthresh to half the current window 2558 * and pull our congestion window back to 2559 * the new ssthresh). 2560 * 2561 * Dup acks mean that packets have left the 2562 * network (they're now cached at the receiver) 2563 * so bump cwnd by the amount in the receiver 2564 * to keep a constant cwnd packets in the 2565 * network. 2566 * 2567 * When using TCP ECN, notify the peer that 2568 * we reduced the cwnd. 2569 */ 2570 /* 2571 * Following 2 kinds of acks should not affect 2572 * dupack counting: 2573 * 1) Old acks 2574 * 2) Acks with SACK but without any new SACK 2575 * information in them. These could result from 2576 * any anomaly in the network like a switch 2577 * duplicating packets or a possible DoS attack. 2578 */ 2579 if (th->th_ack != tp->snd_una || 2580 (tcp_is_sack_recovery(tp, &to) && 2581 (sack_changed == SACK_NOCHANGE))) 2582 break; 2583 else if (!tcp_timer_active(tp, TT_REXMT)) 2584 tp->t_dupacks = 0; 2585 else if (++tp->t_dupacks > tcprexmtthresh || 2586 IN_FASTRECOVERY(tp->t_flags)) { 2587 cc_ack_received(tp, th, nsegs, 2588 CC_DUPACK); 2589 if (V_tcp_do_prr && 2590 IN_FASTRECOVERY(tp->t_flags) && 2591 (tp->t_flags & TF_SACK_PERMIT)) { 2592 tcp_do_prr_ack(tp, th, &to, sack_changed); 2593 } else if (tcp_is_sack_recovery(tp, &to) && 2594 IN_FASTRECOVERY(tp->t_flags)) { 2595 int awnd; 2596 2597 /* 2598 * Compute the amount of data in flight first. 2599 * We can inject new data into the pipe iff 2600 * we have less than 1/2 the original window's 2601 * worth of data in flight. 2602 */ 2603 if (V_tcp_do_newsack) 2604 awnd = tcp_compute_pipe(tp); 2605 else 2606 awnd = (tp->snd_nxt - tp->snd_fack) + 2607 tp->sackhint.sack_bytes_rexmit; 2608 2609 if (awnd < tp->snd_ssthresh) { 2610 tp->snd_cwnd += maxseg; 2611 if (tp->snd_cwnd > tp->snd_ssthresh) 2612 tp->snd_cwnd = tp->snd_ssthresh; 2613 } 2614 } else 2615 tp->snd_cwnd += maxseg; 2616 (void) tcp_output(tp); 2617 goto drop; 2618 } else if (tp->t_dupacks == tcprexmtthresh || 2619 (tp->t_flags & TF_SACK_PERMIT && 2620 V_tcp_do_newsack && 2621 tp->sackhint.sacked_bytes > 2622 (tcprexmtthresh - 1) * maxseg)) { 2623 enter_recovery: 2624 /* 2625 * Above is the RFC6675 trigger condition of 2626 * more than (dupthresh-1)*maxseg sacked data. 2627 * If the count of holes in the 2628 * scoreboard is >= dupthresh, we could 2629 * also enter loss recovery, but don't 2630 * have that value readily available. 2631 */ 2632 tp->t_dupacks = tcprexmtthresh; 2633 tcp_seq onxt = tp->snd_nxt; 2634 2635 /* 2636 * If we're doing sack, or prr, check 2637 * to see if we're already in sack 2638 * recovery. If we're not doing sack, 2639 * check to see if we're in newreno 2640 * recovery. 2641 */ 2642 if (V_tcp_do_prr || 2643 (tp->t_flags & TF_SACK_PERMIT)) { 2644 if (IN_FASTRECOVERY(tp->t_flags)) { 2645 tp->t_dupacks = 0; 2646 break; 2647 } 2648 } else { 2649 if (SEQ_LEQ(th->th_ack, 2650 tp->snd_recover)) { 2651 tp->t_dupacks = 0; 2652 break; 2653 } 2654 } 2655 /* Congestion signal before ack. */ 2656 cc_cong_signal(tp, th, CC_NDUPACK); 2657 cc_ack_received(tp, th, nsegs, 2658 CC_DUPACK); 2659 tcp_timer_activate(tp, TT_REXMT, 0); 2660 tp->t_rtttime = 0; 2661 if (V_tcp_do_prr) { 2662 /* 2663 * snd_ssthresh is already updated by 2664 * cc_cong_signal. 2665 */ 2666 if (tcp_is_sack_recovery(tp, &to)) { 2667 /* 2668 * Exclude Limited Transmit 2669 * segments here 2670 */ 2671 tp->sackhint.prr_delivered = 2672 maxseg; 2673 } else { 2674 tp->sackhint.prr_delivered = 2675 imin(tp->snd_max - tp->snd_una, 2676 imin(INT_MAX / 65536, 2677 tp->t_dupacks) * maxseg); 2678 } 2679 tp->sackhint.recover_fs = max(1, 2680 tp->snd_nxt - tp->snd_una); 2681 } 2682 if (tcp_is_sack_recovery(tp, &to)) { 2683 TCPSTAT_INC( 2684 tcps_sack_recovery_episode); 2685 tp->snd_recover = tp->snd_nxt; 2686 tp->snd_cwnd = maxseg; 2687 (void) tcp_output(tp); 2688 if (SEQ_GT(th->th_ack, tp->snd_una)) 2689 goto resume_partialack; 2690 goto drop; 2691 } 2692 tp->snd_nxt = th->th_ack; 2693 tp->snd_cwnd = maxseg; 2694 (void) tcp_output(tp); 2695 KASSERT(tp->snd_limited <= 2, 2696 ("%s: tp->snd_limited too big", 2697 __func__)); 2698 tp->snd_cwnd = tp->snd_ssthresh + 2699 maxseg * 2700 (tp->t_dupacks - tp->snd_limited); 2701 if (SEQ_GT(onxt, tp->snd_nxt)) 2702 tp->snd_nxt = onxt; 2703 goto drop; 2704 } else if (V_tcp_do_rfc3042) { 2705 /* 2706 * Process first and second duplicate 2707 * ACKs. Each indicates a segment 2708 * leaving the network, creating room 2709 * for more. Make sure we can send a 2710 * packet on reception of each duplicate 2711 * ACK by increasing snd_cwnd by one 2712 * segment. Restore the original 2713 * snd_cwnd after packet transmission. 2714 */ 2715 cc_ack_received(tp, th, nsegs, 2716 CC_DUPACK); 2717 uint32_t oldcwnd = tp->snd_cwnd; 2718 tcp_seq oldsndmax = tp->snd_max; 2719 u_int sent; 2720 int avail; 2721 2722 KASSERT(tp->t_dupacks == 1 || 2723 tp->t_dupacks == 2, 2724 ("%s: dupacks not 1 or 2", 2725 __func__)); 2726 if (tp->t_dupacks == 1) 2727 tp->snd_limited = 0; 2728 tp->snd_cwnd = 2729 (tp->snd_nxt - tp->snd_una) + 2730 (tp->t_dupacks - tp->snd_limited) * 2731 maxseg; 2732 /* 2733 * Only call tcp_output when there 2734 * is new data available to be sent 2735 * or we need to send an ACK. 2736 */ 2737 SOCKBUF_LOCK(&so->so_snd); 2738 avail = sbavail(&so->so_snd) - 2739 (tp->snd_nxt - tp->snd_una); 2740 SOCKBUF_UNLOCK(&so->so_snd); 2741 if (avail > 0 || tp->t_flags & TF_ACKNOW) 2742 (void) tcp_output(tp); 2743 sent = tp->snd_max - oldsndmax; 2744 if (sent > maxseg) { 2745 KASSERT((tp->t_dupacks == 2 && 2746 tp->snd_limited == 0) || 2747 (sent == maxseg + 1 && 2748 tp->t_flags & TF_SENTFIN), 2749 ("%s: sent too much", 2750 __func__)); 2751 tp->snd_limited = 2; 2752 } else if (sent > 0) 2753 ++tp->snd_limited; 2754 tp->snd_cwnd = oldcwnd; 2755 goto drop; 2756 } 2757 } 2758 break; 2759 } else { 2760 /* 2761 * This ack is advancing the left edge, reset the 2762 * counter. 2763 */ 2764 tp->t_dupacks = 0; 2765 /* 2766 * If this ack also has new SACK info, increment the 2767 * counter as per rfc6675. The variable 2768 * sack_changed tracks all changes to the SACK 2769 * scoreboard, including when partial ACKs without 2770 * SACK options are received, and clear the scoreboard 2771 * from the left side. Such partial ACKs should not be 2772 * counted as dupacks here. 2773 */ 2774 if (tcp_is_sack_recovery(tp, &to) && 2775 (sack_changed != SACK_NOCHANGE)) { 2776 tp->t_dupacks++; 2777 /* limit overhead by setting maxseg last */ 2778 if (!IN_FASTRECOVERY(tp->t_flags) && 2779 (tp->sackhint.sacked_bytes > 2780 ((tcprexmtthresh - 1) * 2781 (maxseg = tcp_maxseg(tp))))) { 2782 goto enter_recovery; 2783 } 2784 } 2785 } 2786 2787 resume_partialack: 2788 KASSERT(SEQ_GT(th->th_ack, tp->snd_una), 2789 ("%s: th_ack <= snd_una", __func__)); 2790 2791 /* 2792 * If the congestion window was inflated to account 2793 * for the other side's cached packets, retract it. 2794 */ 2795 if (IN_FASTRECOVERY(tp->t_flags)) { 2796 if (SEQ_LT(th->th_ack, tp->snd_recover)) { 2797 if (tp->t_flags & TF_SACK_PERMIT) 2798 if (V_tcp_do_prr && to.to_flags & TOF_SACK) { 2799 tcp_timer_activate(tp, TT_REXMT, 0); 2800 tp->t_rtttime = 0; 2801 tcp_do_prr_ack(tp, th, &to, sack_changed); 2802 tp->t_flags |= TF_ACKNOW; 2803 (void) tcp_output(tp); 2804 } else 2805 tcp_sack_partialack(tp, th); 2806 else 2807 tcp_newreno_partial_ack(tp, th); 2808 } else 2809 cc_post_recovery(tp, th); 2810 } else if (IN_CONGRECOVERY(tp->t_flags)) { 2811 if (SEQ_LT(th->th_ack, tp->snd_recover)) { 2812 if (V_tcp_do_prr) { 2813 tp->sackhint.delivered_data = BYTES_THIS_ACK(tp, th); 2814 tp->snd_fack = th->th_ack; 2815 /* 2816 * During ECN cwnd reduction 2817 * always use PRR-SSRB 2818 */ 2819 tcp_do_prr_ack(tp, th, &to, SACK_CHANGE); 2820 (void) tcp_output(tp); 2821 } 2822 } else 2823 cc_post_recovery(tp, th); 2824 } 2825 /* 2826 * If we reach this point, ACK is not a duplicate, 2827 * i.e., it ACKs something we sent. 2828 */ 2829 if (tp->t_flags & TF_NEEDSYN) { 2830 /* 2831 * T/TCP: Connection was half-synchronized, and our 2832 * SYN has been ACK'd (so connection is now fully 2833 * synchronized). Go to non-starred state, 2834 * increment snd_una for ACK of SYN, and check if 2835 * we can do window scaling. 2836 */ 2837 tp->t_flags &= ~TF_NEEDSYN; 2838 tp->snd_una++; 2839 /* Do window scaling? */ 2840 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2841 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2842 tp->rcv_scale = tp->request_r_scale; 2843 /* Send window already scaled. */ 2844 } 2845 } 2846 2847 process_ACK: 2848 INP_WLOCK_ASSERT(inp); 2849 2850 /* 2851 * Adjust for the SYN bit in sequence space, 2852 * but don't account for it in cwnd calculations. 2853 * This is for the SYN_RECEIVED, non-simultaneous 2854 * SYN case. SYN_SENT and simultaneous SYN are 2855 * treated elsewhere. 2856 */ 2857 if (incforsyn) 2858 tp->snd_una++; 2859 acked = BYTES_THIS_ACK(tp, th); 2860 KASSERT(acked >= 0, ("%s: acked unexepectedly negative " 2861 "(tp->snd_una=%u, th->th_ack=%u, tp=%p, m=%p)", __func__, 2862 tp->snd_una, th->th_ack, tp, m)); 2863 TCPSTAT_ADD(tcps_rcvackpack, nsegs); 2864 TCPSTAT_ADD(tcps_rcvackbyte, acked); 2865 2866 /* 2867 * If we just performed our first retransmit, and the ACK 2868 * arrives within our recovery window, then it was a mistake 2869 * to do the retransmit in the first place. Recover our 2870 * original cwnd and ssthresh, and proceed to transmit where 2871 * we left off. 2872 */ 2873 if (tp->t_rxtshift == 1 && 2874 tp->t_flags & TF_PREVVALID && 2875 tp->t_badrxtwin != 0 && 2876 to.to_flags & TOF_TS && 2877 to.to_tsecr != 0 && 2878 TSTMP_LT(to.to_tsecr, tp->t_badrxtwin)) 2879 cc_cong_signal(tp, th, CC_RTO_ERR); 2880 2881 /* 2882 * If we have a timestamp reply, update smoothed 2883 * round trip time. If no timestamp is present but 2884 * transmit timer is running and timed sequence 2885 * number was acked, update smoothed round trip time. 2886 * Since we now have an rtt measurement, cancel the 2887 * timer backoff (cf., Phil Karn's retransmit alg.). 2888 * Recompute the initial retransmit timer. 2889 * 2890 * Some boxes send broken timestamp replies 2891 * during the SYN+ACK phase, ignore 2892 * timestamps of 0 or we could calculate a 2893 * huge RTT and blow up the retransmit timer. 2894 */ 2895 if ((to.to_flags & TOF_TS) != 0 && to.to_tsecr) { 2896 uint32_t t; 2897 2898 t = tcp_ts_getticks() - to.to_tsecr; 2899 if (!tp->t_rttlow || tp->t_rttlow > t) 2900 tp->t_rttlow = t; 2901 tcp_xmit_timer(tp, TCP_TS_TO_TICKS(t) + 1); 2902 } else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) { 2903 if (!tp->t_rttlow || tp->t_rttlow > ticks - tp->t_rtttime) 2904 tp->t_rttlow = ticks - tp->t_rtttime; 2905 tcp_xmit_timer(tp, ticks - tp->t_rtttime); 2906 } 2907 2908 SOCKBUF_LOCK(&so->so_snd); 2909 /* 2910 * Clear t_acktime if remote side has ACKd all data in the 2911 * socket buffer and FIN (if applicable). 2912 * Otherwise, update t_acktime if we received a sufficiently 2913 * large ACK. 2914 */ 2915 if ((tp->t_state <= TCPS_CLOSE_WAIT && 2916 acked == sbavail(&so->so_snd)) || 2917 acked > sbavail(&so->so_snd)) 2918 tp->t_acktime = 0; 2919 else if (acked > 1) 2920 tp->t_acktime = ticks; 2921 2922 /* 2923 * If all outstanding data is acked, stop retransmit 2924 * timer and remember to restart (more output or persist). 2925 * If there is more data to be acked, restart retransmit 2926 * timer, using current (possibly backed-off) value. 2927 */ 2928 if (th->th_ack == tp->snd_max) { 2929 tcp_timer_activate(tp, TT_REXMT, 0); 2930 needoutput = 1; 2931 } else if (!tcp_timer_active(tp, TT_PERSIST)) 2932 tcp_timer_activate(tp, TT_REXMT, TP_RXTCUR(tp)); 2933 2934 /* 2935 * If no data (only SYN) was ACK'd, 2936 * skip rest of ACK processing. 2937 */ 2938 if (acked == 0) { 2939 SOCKBUF_UNLOCK(&so->so_snd); 2940 goto step6; 2941 } 2942 2943 /* 2944 * Let the congestion control algorithm update congestion 2945 * control related information. This typically means increasing 2946 * the congestion window. 2947 */ 2948 cc_ack_received(tp, th, nsegs, CC_ACK); 2949 2950 if (acked > sbavail(&so->so_snd)) { 2951 if (tp->snd_wnd >= sbavail(&so->so_snd)) 2952 tp->snd_wnd -= sbavail(&so->so_snd); 2953 else 2954 tp->snd_wnd = 0; 2955 mfree = sbcut_locked(&so->so_snd, 2956 (int)sbavail(&so->so_snd)); 2957 ourfinisacked = 1; 2958 } else { 2959 mfree = sbcut_locked(&so->so_snd, acked); 2960 if (tp->snd_wnd >= (uint32_t) acked) 2961 tp->snd_wnd -= acked; 2962 else 2963 tp->snd_wnd = 0; 2964 ourfinisacked = 0; 2965 } 2966 /* NB: sowwakeup_locked() does an implicit unlock. */ 2967 sowwakeup_locked(so); 2968 m_freem(mfree); 2969 /* Detect una wraparound. */ 2970 if (!IN_RECOVERY(tp->t_flags) && 2971 SEQ_GT(tp->snd_una, tp->snd_recover) && 2972 SEQ_LEQ(th->th_ack, tp->snd_recover)) 2973 tp->snd_recover = th->th_ack - 1; 2974 /* XXXLAS: Can this be moved up into cc_post_recovery? */ 2975 if (IN_RECOVERY(tp->t_flags) && 2976 SEQ_GEQ(th->th_ack, tp->snd_recover)) { 2977 EXIT_RECOVERY(tp->t_flags); 2978 } 2979 tp->snd_una = th->th_ack; 2980 if (tp->t_flags & TF_SACK_PERMIT) { 2981 if (SEQ_GT(tp->snd_una, tp->snd_recover)) 2982 tp->snd_recover = tp->snd_una; 2983 } 2984 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2985 tp->snd_nxt = tp->snd_una; 2986 2987 switch (tp->t_state) { 2988 /* 2989 * In FIN_WAIT_1 STATE in addition to the processing 2990 * for the ESTABLISHED state if our FIN is now acknowledged 2991 * then enter FIN_WAIT_2. 2992 */ 2993 case TCPS_FIN_WAIT_1: 2994 if (ourfinisacked) { 2995 /* 2996 * If we can't receive any more 2997 * data, then closing user can proceed. 2998 * Starting the timer is contrary to the 2999 * specification, but if we don't get a FIN 3000 * we'll hang forever. 3001 */ 3002 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 3003 soisdisconnected(so); 3004 tcp_timer_activate(tp, TT_2MSL, 3005 (tcp_fast_finwait2_recycle ? 3006 tcp_finwait2_timeout : 3007 TP_MAXIDLE(tp))); 3008 } 3009 tcp_state_change(tp, TCPS_FIN_WAIT_2); 3010 } 3011 break; 3012 3013 /* 3014 * In CLOSING STATE in addition to the processing for 3015 * the ESTABLISHED state if the ACK acknowledges our FIN 3016 * then enter the TIME-WAIT state, otherwise ignore 3017 * the segment. 3018 */ 3019 case TCPS_CLOSING: 3020 if (ourfinisacked) { 3021 tcp_twstart(tp); 3022 m_freem(m); 3023 return; 3024 } 3025 break; 3026 3027 /* 3028 * In LAST_ACK, we may still be waiting for data to drain 3029 * and/or to be acked, as well as for the ack of our FIN. 3030 * If our FIN is now acknowledged, delete the TCB, 3031 * enter the closed state and return. 3032 */ 3033 case TCPS_LAST_ACK: 3034 if (ourfinisacked) { 3035 tp = tcp_close(tp); 3036 goto drop; 3037 } 3038 break; 3039 } 3040 } 3041 3042 step6: 3043 INP_WLOCK_ASSERT(inp); 3044 3045 /* 3046 * Update window information. 3047 * Don't look at window if no ACK: TAC's send garbage on first SYN. 3048 */ 3049 if ((thflags & TH_ACK) && 3050 (SEQ_LT(tp->snd_wl1, th->th_seq) || 3051 (tp->snd_wl1 == th->th_seq && (SEQ_LT(tp->snd_wl2, th->th_ack) || 3052 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))) { 3053 /* keep track of pure window updates */ 3054 if (tlen == 0 && 3055 tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) 3056 TCPSTAT_INC(tcps_rcvwinupd); 3057 tp->snd_wnd = tiwin; 3058 tp->snd_wl1 = th->th_seq; 3059 tp->snd_wl2 = th->th_ack; 3060 if (tp->snd_wnd > tp->max_sndwnd) 3061 tp->max_sndwnd = tp->snd_wnd; 3062 needoutput = 1; 3063 } 3064 3065 /* 3066 * Process segments with URG. 3067 */ 3068 if ((thflags & TH_URG) && th->th_urp && 3069 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3070 /* 3071 * This is a kludge, but if we receive and accept 3072 * random urgent pointers, we'll crash in 3073 * soreceive. It's hard to imagine someone 3074 * actually wanting to send this much urgent data. 3075 */ 3076 SOCKBUF_LOCK(&so->so_rcv); 3077 if (th->th_urp + sbavail(&so->so_rcv) > sb_max) { 3078 th->th_urp = 0; /* XXX */ 3079 thflags &= ~TH_URG; /* XXX */ 3080 SOCKBUF_UNLOCK(&so->so_rcv); /* XXX */ 3081 goto dodata; /* XXX */ 3082 } 3083 /* 3084 * If this segment advances the known urgent pointer, 3085 * then mark the data stream. This should not happen 3086 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 3087 * a FIN has been received from the remote side. 3088 * In these states we ignore the URG. 3089 * 3090 * According to RFC961 (Assigned Protocols), 3091 * the urgent pointer points to the last octet 3092 * of urgent data. We continue, however, 3093 * to consider it to indicate the first octet 3094 * of data past the urgent section as the original 3095 * spec states (in one of two places). 3096 */ 3097 if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) { 3098 tp->rcv_up = th->th_seq + th->th_urp; 3099 so->so_oobmark = sbavail(&so->so_rcv) + 3100 (tp->rcv_up - tp->rcv_nxt) - 1; 3101 if (so->so_oobmark == 0) 3102 so->so_rcv.sb_state |= SBS_RCVATMARK; 3103 sohasoutofband(so); 3104 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); 3105 } 3106 SOCKBUF_UNLOCK(&so->so_rcv); 3107 /* 3108 * Remove out of band data so doesn't get presented to user. 3109 * This can happen independent of advancing the URG pointer, 3110 * but if two URG's are pending at once, some out-of-band 3111 * data may creep in... ick. 3112 */ 3113 if (th->th_urp <= (uint32_t)tlen && 3114 !(so->so_options & SO_OOBINLINE)) { 3115 /* hdr drop is delayed */ 3116 tcp_pulloutofband(so, th, m, drop_hdrlen); 3117 } 3118 } else { 3119 /* 3120 * If no out of band data is expected, 3121 * pull receive urgent pointer along 3122 * with the receive window. 3123 */ 3124 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) 3125 tp->rcv_up = tp->rcv_nxt; 3126 } 3127 dodata: /* XXX */ 3128 INP_WLOCK_ASSERT(inp); 3129 3130 /* 3131 * Process the segment text, merging it into the TCP sequencing queue, 3132 * and arranging for acknowledgment of receipt if necessary. 3133 * This process logically involves adjusting tp->rcv_wnd as data 3134 * is presented to the user (this happens in tcp_usrreq.c, 3135 * case PRU_RCVD). If a FIN has already been received on this 3136 * connection then we just ignore the text. 3137 */ 3138 tfo_syn = ((tp->t_state == TCPS_SYN_RECEIVED) && 3139 IS_FASTOPEN(tp->t_flags)); 3140 if ((tlen || (thflags & TH_FIN) || (tfo_syn && tlen > 0)) && 3141 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3142 tcp_seq save_start = th->th_seq; 3143 tcp_seq save_rnxt = tp->rcv_nxt; 3144 int save_tlen = tlen; 3145 m_adj(m, drop_hdrlen); /* delayed header drop */ 3146 /* 3147 * Insert segment which includes th into TCP reassembly queue 3148 * with control block tp. Set thflags to whether reassembly now 3149 * includes a segment with FIN. This handles the common case 3150 * inline (segment is the next to be received on an established 3151 * connection, and the queue is empty), avoiding linkage into 3152 * and removal from the queue and repetition of various 3153 * conversions. 3154 * Set DELACK for segments received in order, but ack 3155 * immediately when segments are out of order (so 3156 * fast retransmit can work). 3157 */ 3158 if (th->th_seq == tp->rcv_nxt && 3159 SEGQ_EMPTY(tp) && 3160 (TCPS_HAVEESTABLISHED(tp->t_state) || 3161 tfo_syn)) { 3162 if (DELAY_ACK(tp, tlen) || tfo_syn) 3163 tp->t_flags |= TF_DELACK; 3164 else 3165 tp->t_flags |= TF_ACKNOW; 3166 tp->rcv_nxt += tlen; 3167 if (tlen && 3168 ((tp->t_flags2 & TF2_FBYTES_COMPLETE) == 0) && 3169 (tp->t_fbyte_in == 0)) { 3170 tp->t_fbyte_in = ticks; 3171 if (tp->t_fbyte_in == 0) 3172 tp->t_fbyte_in = 1; 3173 if (tp->t_fbyte_out && tp->t_fbyte_in) 3174 tp->t_flags2 |= TF2_FBYTES_COMPLETE; 3175 } 3176 thflags = tcp_get_flags(th) & TH_FIN; 3177 TCPSTAT_INC(tcps_rcvpack); 3178 TCPSTAT_ADD(tcps_rcvbyte, tlen); 3179 SOCKBUF_LOCK(&so->so_rcv); 3180 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) 3181 m_freem(m); 3182 else 3183 sbappendstream_locked(&so->so_rcv, m, 0); 3184 tp->t_flags |= TF_WAKESOR; 3185 } else { 3186 /* 3187 * XXX: Due to the header drop above "th" is 3188 * theoretically invalid by now. Fortunately 3189 * m_adj() doesn't actually frees any mbufs 3190 * when trimming from the head. 3191 */ 3192 tcp_seq temp = save_start; 3193 3194 thflags = tcp_reass(tp, th, &temp, &tlen, m); 3195 tp->t_flags |= TF_ACKNOW; 3196 } 3197 if ((tp->t_flags & TF_SACK_PERMIT) && 3198 (save_tlen > 0) && 3199 TCPS_HAVEESTABLISHED(tp->t_state)) { 3200 if ((tlen == 0) && (SEQ_LT(save_start, save_rnxt))) { 3201 /* 3202 * DSACK actually handled in the fastpath 3203 * above. 3204 */ 3205 tcp_update_sack_list(tp, save_start, 3206 save_start + save_tlen); 3207 } else if ((tlen > 0) && SEQ_GT(tp->rcv_nxt, save_rnxt)) { 3208 if ((tp->rcv_numsacks >= 1) && 3209 (tp->sackblks[0].end == save_start)) { 3210 /* 3211 * Partial overlap, recorded at todrop 3212 * above. 3213 */ 3214 tcp_update_sack_list(tp, 3215 tp->sackblks[0].start, 3216 tp->sackblks[0].end); 3217 } else { 3218 tcp_update_dsack_list(tp, save_start, 3219 save_start + save_tlen); 3220 } 3221 } else if (tlen >= save_tlen) { 3222 /* Update of sackblks. */ 3223 tcp_update_dsack_list(tp, save_start, 3224 save_start + save_tlen); 3225 } else if (tlen > 0) { 3226 tcp_update_dsack_list(tp, save_start, 3227 save_start + tlen); 3228 } 3229 } 3230 tcp_handle_wakeup(tp); 3231 #if 0 3232 /* 3233 * Note the amount of data that peer has sent into 3234 * our window, in order to estimate the sender's 3235 * buffer size. 3236 * XXX: Unused. 3237 */ 3238 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt)) 3239 len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); 3240 else 3241 len = so->so_rcv.sb_hiwat; 3242 #endif 3243 } else { 3244 m_freem(m); 3245 thflags &= ~TH_FIN; 3246 } 3247 3248 /* 3249 * If FIN is received ACK the FIN and let the user know 3250 * that the connection is closing. 3251 */ 3252 if (thflags & TH_FIN) { 3253 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3254 /* The socket upcall is handled by socantrcvmore. */ 3255 socantrcvmore(so); 3256 /* 3257 * If connection is half-synchronized 3258 * (ie NEEDSYN flag on) then delay ACK, 3259 * so it may be piggybacked when SYN is sent. 3260 * Otherwise, since we received a FIN then no 3261 * more input can be expected, send ACK now. 3262 */ 3263 if (tp->t_flags & TF_NEEDSYN) 3264 tp->t_flags |= TF_DELACK; 3265 else 3266 tp->t_flags |= TF_ACKNOW; 3267 tp->rcv_nxt++; 3268 } 3269 switch (tp->t_state) { 3270 /* 3271 * In SYN_RECEIVED and ESTABLISHED STATES 3272 * enter the CLOSE_WAIT state. 3273 */ 3274 case TCPS_SYN_RECEIVED: 3275 tp->t_starttime = ticks; 3276 /* FALLTHROUGH */ 3277 case TCPS_ESTABLISHED: 3278 tcp_state_change(tp, TCPS_CLOSE_WAIT); 3279 break; 3280 3281 /* 3282 * If still in FIN_WAIT_1 STATE FIN has not been acked so 3283 * enter the CLOSING state. 3284 */ 3285 case TCPS_FIN_WAIT_1: 3286 tcp_state_change(tp, TCPS_CLOSING); 3287 break; 3288 3289 /* 3290 * In FIN_WAIT_2 state enter the TIME_WAIT state, 3291 * starting the time-wait timer, turning off the other 3292 * standard timers. 3293 */ 3294 case TCPS_FIN_WAIT_2: 3295 tcp_twstart(tp); 3296 return; 3297 } 3298 } 3299 TCP_PROBE3(debug__input, tp, th, m); 3300 3301 /* 3302 * Return any desired output. 3303 */ 3304 if (needoutput || (tp->t_flags & TF_ACKNOW)) 3305 (void) tcp_output(tp); 3306 3307 check_delack: 3308 INP_WLOCK_ASSERT(inp); 3309 3310 if (tp->t_flags & TF_DELACK) { 3311 tp->t_flags &= ~TF_DELACK; 3312 tcp_timer_activate(tp, TT_DELACK, tcp_delacktime); 3313 } 3314 INP_WUNLOCK(inp); 3315 return; 3316 3317 dropafterack: 3318 /* 3319 * Generate an ACK dropping incoming segment if it occupies 3320 * sequence space, where the ACK reflects our state. 3321 * 3322 * We can now skip the test for the RST flag since all 3323 * paths to this code happen after packets containing 3324 * RST have been dropped. 3325 * 3326 * In the SYN-RECEIVED state, don't send an ACK unless the 3327 * segment we received passes the SYN-RECEIVED ACK test. 3328 * If it fails send a RST. This breaks the loop in the 3329 * "LAND" DoS attack, and also prevents an ACK storm 3330 * between two listening ports that have been sent forged 3331 * SYN segments, each with the source address of the other. 3332 */ 3333 if (tp->t_state == TCPS_SYN_RECEIVED && (thflags & TH_ACK) && 3334 (SEQ_GT(tp->snd_una, th->th_ack) || 3335 SEQ_GT(th->th_ack, tp->snd_max)) ) { 3336 rstreason = BANDLIM_RST_OPENPORT; 3337 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 3338 goto dropwithreset; 3339 } 3340 TCP_PROBE3(debug__input, tp, th, m); 3341 tp->t_flags |= TF_ACKNOW; 3342 (void) tcp_output(tp); 3343 INP_WUNLOCK(inp); 3344 m_freem(m); 3345 return; 3346 3347 dropwithreset: 3348 if (tp != NULL) { 3349 tcp_dropwithreset(m, th, tp, tlen, rstreason); 3350 INP_WUNLOCK(inp); 3351 } else 3352 tcp_dropwithreset(m, th, NULL, tlen, rstreason); 3353 return; 3354 3355 drop: 3356 /* 3357 * Drop space held by incoming segment and return. 3358 */ 3359 TCP_PROBE3(debug__input, tp, th, m); 3360 if (tp != NULL) { 3361 INP_WUNLOCK(inp); 3362 } 3363 m_freem(m); 3364 } 3365 3366 /* 3367 * Issue RST and make ACK acceptable to originator of segment. 3368 * The mbuf must still include the original packet header. 3369 * tp may be NULL. 3370 */ 3371 void 3372 tcp_dropwithreset(struct mbuf *m, struct tcphdr *th, struct tcpcb *tp, 3373 int tlen, int rstreason) 3374 { 3375 #ifdef INET 3376 struct ip *ip; 3377 #endif 3378 #ifdef INET6 3379 struct ip6_hdr *ip6; 3380 #endif 3381 3382 if (tp != NULL) { 3383 INP_LOCK_ASSERT(tptoinpcb(tp)); 3384 } 3385 3386 /* Don't bother if destination was broadcast/multicast. */ 3387 if ((tcp_get_flags(th) & TH_RST) || m->m_flags & (M_BCAST|M_MCAST)) 3388 goto drop; 3389 #ifdef INET6 3390 if (mtod(m, struct ip *)->ip_v == 6) { 3391 ip6 = mtod(m, struct ip6_hdr *); 3392 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 3393 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) 3394 goto drop; 3395 /* IPv6 anycast check is done at tcp6_input() */ 3396 } 3397 #endif 3398 #if defined(INET) && defined(INET6) 3399 else 3400 #endif 3401 #ifdef INET 3402 { 3403 ip = mtod(m, struct ip *); 3404 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || 3405 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 3406 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || 3407 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 3408 goto drop; 3409 } 3410 #endif 3411 3412 /* Perform bandwidth limiting. */ 3413 if (badport_bandlim(rstreason) < 0) 3414 goto drop; 3415 3416 /* tcp_respond consumes the mbuf chain. */ 3417 if (tcp_get_flags(th) & TH_ACK) { 3418 tcp_respond(tp, mtod(m, void *), th, m, (tcp_seq)0, 3419 th->th_ack, TH_RST); 3420 } else { 3421 if (tcp_get_flags(th) & TH_SYN) 3422 tlen++; 3423 if (tcp_get_flags(th) & TH_FIN) 3424 tlen++; 3425 tcp_respond(tp, mtod(m, void *), th, m, th->th_seq+tlen, 3426 (tcp_seq)0, TH_RST|TH_ACK); 3427 } 3428 return; 3429 drop: 3430 m_freem(m); 3431 } 3432 3433 /* 3434 * Parse TCP options and place in tcpopt. 3435 */ 3436 void 3437 tcp_dooptions(struct tcpopt *to, u_char *cp, int cnt, int flags) 3438 { 3439 int opt, optlen; 3440 3441 to->to_flags = 0; 3442 for (; cnt > 0; cnt -= optlen, cp += optlen) { 3443 opt = cp[0]; 3444 if (opt == TCPOPT_EOL) 3445 break; 3446 if (opt == TCPOPT_NOP) 3447 optlen = 1; 3448 else { 3449 if (cnt < 2) 3450 break; 3451 optlen = cp[1]; 3452 if (optlen < 2 || optlen > cnt) 3453 break; 3454 } 3455 switch (opt) { 3456 case TCPOPT_MAXSEG: 3457 if (optlen != TCPOLEN_MAXSEG) 3458 continue; 3459 if (!(flags & TO_SYN)) 3460 continue; 3461 to->to_flags |= TOF_MSS; 3462 bcopy((char *)cp + 2, 3463 (char *)&to->to_mss, sizeof(to->to_mss)); 3464 to->to_mss = ntohs(to->to_mss); 3465 break; 3466 case TCPOPT_WINDOW: 3467 if (optlen != TCPOLEN_WINDOW) 3468 continue; 3469 if (!(flags & TO_SYN)) 3470 continue; 3471 to->to_flags |= TOF_SCALE; 3472 to->to_wscale = min(cp[2], TCP_MAX_WINSHIFT); 3473 break; 3474 case TCPOPT_TIMESTAMP: 3475 if (optlen != TCPOLEN_TIMESTAMP) 3476 continue; 3477 to->to_flags |= TOF_TS; 3478 bcopy((char *)cp + 2, 3479 (char *)&to->to_tsval, sizeof(to->to_tsval)); 3480 to->to_tsval = ntohl(to->to_tsval); 3481 bcopy((char *)cp + 6, 3482 (char *)&to->to_tsecr, sizeof(to->to_tsecr)); 3483 to->to_tsecr = ntohl(to->to_tsecr); 3484 break; 3485 case TCPOPT_SIGNATURE: 3486 /* 3487 * In order to reply to a host which has set the 3488 * TCP_SIGNATURE option in its initial SYN, we have 3489 * to record the fact that the option was observed 3490 * here for the syncache code to perform the correct 3491 * response. 3492 */ 3493 if (optlen != TCPOLEN_SIGNATURE) 3494 continue; 3495 to->to_flags |= TOF_SIGNATURE; 3496 to->to_signature = cp + 2; 3497 break; 3498 case TCPOPT_SACK_PERMITTED: 3499 if (optlen != TCPOLEN_SACK_PERMITTED) 3500 continue; 3501 if (!(flags & TO_SYN)) 3502 continue; 3503 if (!V_tcp_do_sack) 3504 continue; 3505 to->to_flags |= TOF_SACKPERM; 3506 break; 3507 case TCPOPT_SACK: 3508 if (optlen <= 2 || (optlen - 2) % TCPOLEN_SACK != 0) 3509 continue; 3510 if (flags & TO_SYN) 3511 continue; 3512 to->to_flags |= TOF_SACK; 3513 to->to_nsacks = (optlen - 2) / TCPOLEN_SACK; 3514 to->to_sacks = cp + 2; 3515 TCPSTAT_INC(tcps_sack_rcv_blocks); 3516 break; 3517 case TCPOPT_FAST_OPEN: 3518 /* 3519 * Cookie length validation is performed by the 3520 * server side cookie checking code or the client 3521 * side cookie cache update code. 3522 */ 3523 if (!(flags & TO_SYN)) 3524 continue; 3525 if (!V_tcp_fastopen_client_enable && 3526 !V_tcp_fastopen_server_enable) 3527 continue; 3528 to->to_flags |= TOF_FASTOPEN; 3529 to->to_tfo_len = optlen - 2; 3530 to->to_tfo_cookie = to->to_tfo_len ? cp + 2 : NULL; 3531 break; 3532 default: 3533 continue; 3534 } 3535 } 3536 } 3537 3538 /* 3539 * Pull out of band byte out of a segment so 3540 * it doesn't appear in the user's data queue. 3541 * It is still reflected in the segment length for 3542 * sequencing purposes. 3543 */ 3544 void 3545 tcp_pulloutofband(struct socket *so, struct tcphdr *th, struct mbuf *m, 3546 int off) 3547 { 3548 int cnt = off + th->th_urp - 1; 3549 3550 while (cnt >= 0) { 3551 if (m->m_len > cnt) { 3552 char *cp = mtod(m, caddr_t) + cnt; 3553 struct tcpcb *tp = sototcpcb(so); 3554 3555 INP_WLOCK_ASSERT(tptoinpcb(tp)); 3556 3557 tp->t_iobc = *cp; 3558 tp->t_oobflags |= TCPOOB_HAVEDATA; 3559 bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); 3560 m->m_len--; 3561 if (m->m_flags & M_PKTHDR) 3562 m->m_pkthdr.len--; 3563 return; 3564 } 3565 cnt -= m->m_len; 3566 m = m->m_next; 3567 if (m == NULL) 3568 break; 3569 } 3570 panic("tcp_pulloutofband"); 3571 } 3572 3573 /* 3574 * Collect new round-trip time estimate 3575 * and update averages and current timeout. 3576 */ 3577 void 3578 tcp_xmit_timer(struct tcpcb *tp, int rtt) 3579 { 3580 int delta; 3581 3582 INP_WLOCK_ASSERT(tptoinpcb(tp)); 3583 3584 TCPSTAT_INC(tcps_rttupdated); 3585 if (tp->t_rttupdated < UCHAR_MAX) 3586 tp->t_rttupdated++; 3587 #ifdef STATS 3588 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_RTT, 3589 imax(0, rtt * 1000 / hz)); 3590 #endif 3591 if ((tp->t_srtt != 0) && (tp->t_rxtshift <= TCP_RTT_INVALIDATE)) { 3592 /* 3593 * srtt is stored as fixed point with 5 bits after the 3594 * binary point (i.e., scaled by 8). The following magic 3595 * is equivalent to the smoothing algorithm in rfc793 with 3596 * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed 3597 * point). Adjust rtt to origin 0. 3598 */ 3599 delta = ((rtt - 1) << TCP_DELTA_SHIFT) 3600 - (tp->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT)); 3601 3602 if ((tp->t_srtt += delta) <= 0) 3603 tp->t_srtt = 1; 3604 3605 /* 3606 * We accumulate a smoothed rtt variance (actually, a 3607 * smoothed mean difference), then set the retransmit 3608 * timer to smoothed rtt + 4 times the smoothed variance. 3609 * rttvar is stored as fixed point with 4 bits after the 3610 * binary point (scaled by 16). The following is 3611 * equivalent to rfc793 smoothing with an alpha of .75 3612 * (rttvar = rttvar*3/4 + |delta| / 4). This replaces 3613 * rfc793's wired-in beta. 3614 */ 3615 if (delta < 0) 3616 delta = -delta; 3617 delta -= tp->t_rttvar >> (TCP_RTTVAR_SHIFT - TCP_DELTA_SHIFT); 3618 if ((tp->t_rttvar += delta) <= 0) 3619 tp->t_rttvar = 1; 3620 } else { 3621 /* 3622 * No rtt measurement yet - use the unsmoothed rtt. 3623 * Set the variance to half the rtt (so our first 3624 * retransmit happens at 3*rtt). 3625 */ 3626 tp->t_srtt = rtt << TCP_RTT_SHIFT; 3627 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1); 3628 } 3629 tp->t_rtttime = 0; 3630 tp->t_rxtshift = 0; 3631 3632 /* 3633 * the retransmit should happen at rtt + 4 * rttvar. 3634 * Because of the way we do the smoothing, srtt and rttvar 3635 * will each average +1/2 tick of bias. When we compute 3636 * the retransmit timer, we want 1/2 tick of rounding and 3637 * 1 extra tick because of +-1/2 tick uncertainty in the 3638 * firing of the timer. The bias will give us exactly the 3639 * 1.5 tick we need. But, because the bias is 3640 * statistical, we have to test that we don't drop below 3641 * the minimum feasible timer (which is 2 ticks). 3642 */ 3643 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), 3644 max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX); 3645 3646 /* 3647 * We received an ack for a packet that wasn't retransmitted; 3648 * it is probably safe to discard any error indications we've 3649 * received recently. This isn't quite right, but close enough 3650 * for now (a route might have failed after we sent a segment, 3651 * and the return path might not be symmetrical). 3652 */ 3653 tp->t_softerror = 0; 3654 } 3655 3656 /* 3657 * Determine a reasonable value for maxseg size. 3658 * If the route is known, check route for mtu. 3659 * If none, use an mss that can be handled on the outgoing interface 3660 * without forcing IP to fragment. If no route is found, route has no mtu, 3661 * or the destination isn't local, use a default, hopefully conservative 3662 * size (usually 512 or the default IP max size, but no more than the mtu 3663 * of the interface), as we can't discover anything about intervening 3664 * gateways or networks. We also initialize the congestion/slow start 3665 * window to be a single segment if the destination isn't local. 3666 * While looking at the routing entry, we also initialize other path-dependent 3667 * parameters from pre-set or cached values in the routing entry. 3668 * 3669 * NOTE that resulting t_maxseg doesn't include space for TCP options or 3670 * IP options, e.g. IPSEC data, since length of this data may vary, and 3671 * thus it is calculated for every segment separately in tcp_output(). 3672 * 3673 * NOTE that this routine is only called when we process an incoming 3674 * segment, or an ICMP need fragmentation datagram. Outgoing SYN/ACK MSS 3675 * settings are handled in tcp_mssopt(). 3676 */ 3677 void 3678 tcp_mss_update(struct tcpcb *tp, int offer, int mtuoffer, 3679 struct hc_metrics_lite *metricptr, struct tcp_ifcap *cap) 3680 { 3681 int mss = 0; 3682 uint32_t maxmtu = 0; 3683 struct inpcb *inp = tptoinpcb(tp); 3684 struct hc_metrics_lite metrics; 3685 #ifdef INET6 3686 int isipv6 = ((inp->inp_vflag & INP_IPV6) != 0) ? 1 : 0; 3687 size_t min_protoh = isipv6 ? 3688 sizeof (struct ip6_hdr) + sizeof (struct tcphdr) : 3689 sizeof (struct tcpiphdr); 3690 #else 3691 size_t min_protoh = sizeof(struct tcpiphdr); 3692 #endif 3693 3694 INP_WLOCK_ASSERT(inp); 3695 3696 if (tp->t_port) 3697 min_protoh += V_tcp_udp_tunneling_overhead; 3698 if (mtuoffer != -1) { 3699 KASSERT(offer == -1, ("%s: conflict", __func__)); 3700 offer = mtuoffer - min_protoh; 3701 } 3702 3703 /* Initialize. */ 3704 #ifdef INET6 3705 if (isipv6) { 3706 maxmtu = tcp_maxmtu6(&inp->inp_inc, cap); 3707 tp->t_maxseg = V_tcp_v6mssdflt; 3708 } 3709 #endif 3710 #if defined(INET) && defined(INET6) 3711 else 3712 #endif 3713 #ifdef INET 3714 { 3715 maxmtu = tcp_maxmtu(&inp->inp_inc, cap); 3716 tp->t_maxseg = V_tcp_mssdflt; 3717 } 3718 #endif 3719 3720 /* 3721 * No route to sender, stay with default mss and return. 3722 */ 3723 if (maxmtu == 0) { 3724 /* 3725 * In case we return early we need to initialize metrics 3726 * to a defined state as tcp_hc_get() would do for us 3727 * if there was no cache hit. 3728 */ 3729 if (metricptr != NULL) 3730 bzero(metricptr, sizeof(struct hc_metrics_lite)); 3731 return; 3732 } 3733 3734 /* What have we got? */ 3735 switch (offer) { 3736 case 0: 3737 /* 3738 * Offer == 0 means that there was no MSS on the SYN 3739 * segment, in this case we use tcp_mssdflt as 3740 * already assigned to t_maxseg above. 3741 */ 3742 offer = tp->t_maxseg; 3743 break; 3744 3745 case -1: 3746 /* 3747 * Offer == -1 means that we didn't receive SYN yet. 3748 */ 3749 /* FALLTHROUGH */ 3750 3751 default: 3752 /* 3753 * Prevent DoS attack with too small MSS. Round up 3754 * to at least minmss. 3755 */ 3756 offer = max(offer, V_tcp_minmss); 3757 } 3758 3759 /* 3760 * rmx information is now retrieved from tcp_hostcache. 3761 */ 3762 tcp_hc_get(&inp->inp_inc, &metrics); 3763 if (metricptr != NULL) 3764 bcopy(&metrics, metricptr, sizeof(struct hc_metrics_lite)); 3765 3766 /* 3767 * If there's a discovered mtu in tcp hostcache, use it. 3768 * Else, use the link mtu. 3769 */ 3770 if (metrics.rmx_mtu) 3771 mss = min(metrics.rmx_mtu, maxmtu) - min_protoh; 3772 else { 3773 #ifdef INET6 3774 if (isipv6) { 3775 mss = maxmtu - min_protoh; 3776 if (!V_path_mtu_discovery && 3777 !in6_localaddr(&inp->in6p_faddr)) 3778 mss = min(mss, V_tcp_v6mssdflt); 3779 } 3780 #endif 3781 #if defined(INET) && defined(INET6) 3782 else 3783 #endif 3784 #ifdef INET 3785 { 3786 mss = maxmtu - min_protoh; 3787 if (!V_path_mtu_discovery && 3788 !in_localaddr(inp->inp_faddr)) 3789 mss = min(mss, V_tcp_mssdflt); 3790 } 3791 #endif 3792 /* 3793 * XXX - The above conditional (mss = maxmtu - min_protoh) 3794 * probably violates the TCP spec. 3795 * The problem is that, since we don't know the 3796 * other end's MSS, we are supposed to use a conservative 3797 * default. But, if we do that, then MTU discovery will 3798 * never actually take place, because the conservative 3799 * default is much less than the MTUs typically seen 3800 * on the Internet today. For the moment, we'll sweep 3801 * this under the carpet. 3802 * 3803 * The conservative default might not actually be a problem 3804 * if the only case this occurs is when sending an initial 3805 * SYN with options and data to a host we've never talked 3806 * to before. Then, they will reply with an MSS value which 3807 * will get recorded and the new parameters should get 3808 * recomputed. For Further Study. 3809 */ 3810 } 3811 mss = min(mss, offer); 3812 3813 /* 3814 * Sanity check: make sure that maxseg will be large 3815 * enough to allow some data on segments even if the 3816 * all the option space is used (40bytes). Otherwise 3817 * funny things may happen in tcp_output. 3818 * 3819 * XXXGL: shouldn't we reserve space for IP/IPv6 options? 3820 */ 3821 mss = max(mss, 64); 3822 3823 tp->t_maxseg = mss; 3824 } 3825 3826 void 3827 tcp_mss(struct tcpcb *tp, int offer) 3828 { 3829 int mss; 3830 uint32_t bufsize; 3831 struct inpcb *inp = tptoinpcb(tp); 3832 struct socket *so; 3833 struct hc_metrics_lite metrics; 3834 struct tcp_ifcap cap; 3835 3836 KASSERT(tp != NULL, ("%s: tp == NULL", __func__)); 3837 3838 bzero(&cap, sizeof(cap)); 3839 tcp_mss_update(tp, offer, -1, &metrics, &cap); 3840 3841 mss = tp->t_maxseg; 3842 3843 /* 3844 * If there's a pipesize, change the socket buffer to that size, 3845 * don't change if sb_hiwat is different than default (then it 3846 * has been changed on purpose with setsockopt). 3847 * Make the socket buffers an integral number of mss units; 3848 * if the mss is larger than the socket buffer, decrease the mss. 3849 */ 3850 so = inp->inp_socket; 3851 SOCKBUF_LOCK(&so->so_snd); 3852 if ((so->so_snd.sb_hiwat == V_tcp_sendspace) && metrics.rmx_sendpipe) 3853 bufsize = metrics.rmx_sendpipe; 3854 else 3855 bufsize = so->so_snd.sb_hiwat; 3856 if (bufsize < mss) 3857 mss = bufsize; 3858 else { 3859 bufsize = roundup(bufsize, mss); 3860 if (bufsize > sb_max) 3861 bufsize = sb_max; 3862 if (bufsize > so->so_snd.sb_hiwat) 3863 (void)sbreserve_locked(so, SO_SND, bufsize, NULL); 3864 } 3865 SOCKBUF_UNLOCK(&so->so_snd); 3866 /* 3867 * Sanity check: make sure that maxseg will be large 3868 * enough to allow some data on segments even if the 3869 * all the option space is used (40bytes). Otherwise 3870 * funny things may happen in tcp_output. 3871 * 3872 * XXXGL: shouldn't we reserve space for IP/IPv6 options? 3873 */ 3874 tp->t_maxseg = max(mss, 64); 3875 3876 SOCKBUF_LOCK(&so->so_rcv); 3877 if ((so->so_rcv.sb_hiwat == V_tcp_recvspace) && metrics.rmx_recvpipe) 3878 bufsize = metrics.rmx_recvpipe; 3879 else 3880 bufsize = so->so_rcv.sb_hiwat; 3881 if (bufsize > mss) { 3882 bufsize = roundup(bufsize, mss); 3883 if (bufsize > sb_max) 3884 bufsize = sb_max; 3885 if (bufsize > so->so_rcv.sb_hiwat) 3886 (void)sbreserve_locked(so, SO_RCV, bufsize, NULL); 3887 } 3888 SOCKBUF_UNLOCK(&so->so_rcv); 3889 3890 /* Check the interface for TSO capabilities. */ 3891 if (cap.ifcap & CSUM_TSO) { 3892 tp->t_flags |= TF_TSO; 3893 tp->t_tsomax = cap.tsomax; 3894 tp->t_tsomaxsegcount = cap.tsomaxsegcount; 3895 tp->t_tsomaxsegsize = cap.tsomaxsegsize; 3896 } 3897 } 3898 3899 /* 3900 * Determine the MSS option to send on an outgoing SYN. 3901 */ 3902 int 3903 tcp_mssopt(struct in_conninfo *inc) 3904 { 3905 int mss = 0; 3906 uint32_t thcmtu = 0; 3907 uint32_t maxmtu = 0; 3908 size_t min_protoh; 3909 3910 KASSERT(inc != NULL, ("tcp_mssopt with NULL in_conninfo pointer")); 3911 3912 #ifdef INET6 3913 if (inc->inc_flags & INC_ISIPV6) { 3914 mss = V_tcp_v6mssdflt; 3915 maxmtu = tcp_maxmtu6(inc, NULL); 3916 min_protoh = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 3917 } 3918 #endif 3919 #if defined(INET) && defined(INET6) 3920 else 3921 #endif 3922 #ifdef INET 3923 { 3924 mss = V_tcp_mssdflt; 3925 maxmtu = tcp_maxmtu(inc, NULL); 3926 min_protoh = sizeof(struct tcpiphdr); 3927 } 3928 #endif 3929 #if defined(INET6) || defined(INET) 3930 thcmtu = tcp_hc_getmtu(inc); /* IPv4 and IPv6 */ 3931 #endif 3932 3933 if (maxmtu && thcmtu) 3934 mss = min(maxmtu, thcmtu) - min_protoh; 3935 else if (maxmtu || thcmtu) 3936 mss = max(maxmtu, thcmtu) - min_protoh; 3937 3938 return (mss); 3939 } 3940 3941 void 3942 tcp_do_prr_ack(struct tcpcb *tp, struct tcphdr *th, struct tcpopt *to, sackstatus_t sack_changed) 3943 { 3944 int snd_cnt = 0, limit = 0, del_data = 0, pipe = 0; 3945 int maxseg = tcp_maxseg(tp); 3946 3947 INP_WLOCK_ASSERT(tptoinpcb(tp)); 3948 3949 /* 3950 * Compute the amount of data that this ACK is indicating 3951 * (del_data) and an estimate of how many bytes are in the 3952 * network. 3953 */ 3954 if (tcp_is_sack_recovery(tp, to) || 3955 (IN_CONGRECOVERY(tp->t_flags) && 3956 !IN_FASTRECOVERY(tp->t_flags))) { 3957 del_data = tp->sackhint.delivered_data; 3958 if (V_tcp_do_newsack) 3959 pipe = tcp_compute_pipe(tp); 3960 else 3961 pipe = (tp->snd_nxt - tp->snd_fack) + 3962 tp->sackhint.sack_bytes_rexmit; 3963 } else { 3964 if (tp->sackhint.prr_delivered < (tcprexmtthresh * maxseg + 3965 tp->snd_recover - tp->snd_una)) 3966 del_data = maxseg; 3967 pipe = imax(0, tp->snd_max - tp->snd_una - 3968 imin(INT_MAX / 65536, tp->t_dupacks) * maxseg); 3969 } 3970 tp->sackhint.prr_delivered += del_data; 3971 /* 3972 * Proportional Rate Reduction 3973 */ 3974 if (pipe >= tp->snd_ssthresh) { 3975 if (tp->sackhint.recover_fs == 0) 3976 tp->sackhint.recover_fs = 3977 imax(1, tp->snd_nxt - tp->snd_una); 3978 snd_cnt = howmany((long)tp->sackhint.prr_delivered * 3979 tp->snd_ssthresh, tp->sackhint.recover_fs) - 3980 tp->sackhint.prr_out; 3981 } else { 3982 /* 3983 * PRR 6937bis heuristic: 3984 * - A partial ack without SACK block beneath snd_recover 3985 * indicates further loss. 3986 * - An SACK scoreboard update adding a new hole indicates 3987 * further loss, so be conservative and send at most one 3988 * segment. 3989 * - Prevent ACK splitting attacks, by being conservative 3990 * when no new data is acked. 3991 */ 3992 if ((sack_changed == SACK_NEWLOSS) || (del_data == 0)) 3993 limit = tp->sackhint.prr_delivered - 3994 tp->sackhint.prr_out; 3995 else 3996 limit = imax(tp->sackhint.prr_delivered - 3997 tp->sackhint.prr_out, del_data) + 3998 maxseg; 3999 snd_cnt = imin((tp->snd_ssthresh - pipe), limit); 4000 } 4001 snd_cnt = imax(snd_cnt, 0) / maxseg; 4002 /* 4003 * Send snd_cnt new data into the network in response to this ack. 4004 * If there is going to be a SACK retransmission, adjust snd_cwnd 4005 * accordingly. 4006 */ 4007 if (IN_FASTRECOVERY(tp->t_flags)) { 4008 if (tcp_is_sack_recovery(tp, to)) { 4009 tp->snd_cwnd = tp->snd_nxt - tp->snd_recover + 4010 tp->sackhint.sack_bytes_rexmit + 4011 (snd_cnt * maxseg); 4012 } else { 4013 tp->snd_cwnd = (tp->snd_max - tp->snd_una) + 4014 (snd_cnt * maxseg); 4015 } 4016 } else if (IN_CONGRECOVERY(tp->t_flags)) 4017 tp->snd_cwnd = pipe - del_data + (snd_cnt * maxseg); 4018 tp->snd_cwnd = imax(maxseg, tp->snd_cwnd); 4019 } 4020 4021 /* 4022 * On a partial ack arrives, force the retransmission of the 4023 * next unacknowledged segment. Do not clear tp->t_dupacks. 4024 * By setting snd_nxt to ti_ack, this forces retransmission timer to 4025 * be started again. 4026 */ 4027 void 4028 tcp_newreno_partial_ack(struct tcpcb *tp, struct tcphdr *th) 4029 { 4030 tcp_seq onxt = tp->snd_nxt; 4031 uint32_t ocwnd = tp->snd_cwnd; 4032 u_int maxseg = tcp_maxseg(tp); 4033 4034 INP_WLOCK_ASSERT(tptoinpcb(tp)); 4035 4036 tcp_timer_activate(tp, TT_REXMT, 0); 4037 tp->t_rtttime = 0; 4038 tp->snd_nxt = th->th_ack; 4039 /* 4040 * Set snd_cwnd to one segment beyond acknowledged offset. 4041 * (tp->snd_una has not yet been updated when this function is called.) 4042 */ 4043 tp->snd_cwnd = maxseg + BYTES_THIS_ACK(tp, th); 4044 tp->t_flags |= TF_ACKNOW; 4045 (void) tcp_output(tp); 4046 tp->snd_cwnd = ocwnd; 4047 if (SEQ_GT(onxt, tp->snd_nxt)) 4048 tp->snd_nxt = onxt; 4049 /* 4050 * Partial window deflation. Relies on fact that tp->snd_una 4051 * not updated yet. 4052 */ 4053 if (tp->snd_cwnd > BYTES_THIS_ACK(tp, th)) 4054 tp->snd_cwnd -= BYTES_THIS_ACK(tp, th); 4055 else 4056 tp->snd_cwnd = 0; 4057 tp->snd_cwnd += maxseg; 4058 } 4059 4060 int 4061 tcp_compute_pipe(struct tcpcb *tp) 4062 { 4063 if (tp->t_fb->tfb_compute_pipe == NULL) { 4064 return (tp->snd_max - tp->snd_una + 4065 tp->sackhint.sack_bytes_rexmit - 4066 tp->sackhint.sacked_bytes - 4067 tp->sackhint.lost_bytes); 4068 } else { 4069 return((*tp->t_fb->tfb_compute_pipe)(tp)); 4070 } 4071 } 4072 4073 uint32_t 4074 tcp_compute_initwnd(uint32_t maxseg) 4075 { 4076 /* 4077 * Calculate the Initial Window, also used as Restart Window 4078 * 4079 * RFC5681 Section 3.1 specifies the default conservative values. 4080 * RFC3390 specifies slightly more aggressive values. 4081 * RFC6928 increases it to ten segments. 4082 * Support for user specified value for initial flight size. 4083 */ 4084 if (V_tcp_initcwnd_segments) 4085 return min(V_tcp_initcwnd_segments * maxseg, 4086 max(2 * maxseg, V_tcp_initcwnd_segments * 1460)); 4087 else if (V_tcp_do_rfc3390) 4088 return min(4 * maxseg, max(2 * maxseg, 4380)); 4089 else { 4090 /* Per RFC5681 Section 3.1 */ 4091 if (maxseg > 2190) 4092 return (2 * maxseg); 4093 else if (maxseg > 1095) 4094 return (3 * maxseg); 4095 else 4096 return (4 * maxseg); 4097 } 4098 } 4099