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 50 #include <sys/cdefs.h> 51 #include "opt_inet.h" 52 #include "opt_inet6.h" 53 #include "opt_ipsec.h" 54 #include "opt_rss.h" 55 56 #include <sys/param.h> 57 #include <sys/arb.h> 58 #include <sys/kernel.h> 59 #ifdef TCP_HHOOK 60 #include <sys/hhook.h> 61 #endif 62 #include <sys/malloc.h> 63 #include <sys/mbuf.h> 64 #include <sys/proc.h> /* for proc0 declaration */ 65 #include <sys/protosw.h> 66 #include <sys/qmath.h> 67 #include <sys/sdt.h> 68 #include <sys/signalvar.h> 69 #include <sys/socket.h> 70 #include <sys/socketvar.h> 71 #include <sys/sysctl.h> 72 #include <sys/syslog.h> 73 #include <sys/systm.h> 74 #include <sys/stats.h> 75 76 #include <machine/cpu.h> /* before tcp_seq.h, for tcp_random18() */ 77 78 #include <vm/uma.h> 79 80 #include <net/if.h> 81 #include <net/if_var.h> 82 #include <net/route.h> 83 #include <net/rss_config.h> 84 #include <net/vnet.h> 85 86 #define TCPSTATES /* for logging */ 87 88 #include <netinet/in.h> 89 #include <netinet/in_kdtrace.h> 90 #include <netinet/in_pcb.h> 91 #include <netinet/in_rss.h> 92 #include <netinet/in_systm.h> 93 #include <netinet/ip.h> 94 #include <netinet/ip_icmp.h> /* required for icmp_var.h */ 95 #include <netinet/icmp_var.h> /* for ICMP_BANDLIM */ 96 #include <netinet/ip_var.h> 97 #include <netinet/ip_options.h> 98 #include <netinet/ip6.h> 99 #include <netinet/icmp6.h> 100 #include <netinet6/in6_pcb.h> 101 #include <netinet6/in6_rss.h> 102 #include <netinet6/in6_var.h> 103 #include <netinet6/ip6_var.h> 104 #include <netinet6/nd6.h> 105 #include <netinet/tcp.h> 106 #include <netinet/tcp_fsm.h> 107 #include <netinet/tcp_seq.h> 108 #include <netinet/tcp_timer.h> 109 #include <netinet/tcp_var.h> 110 #include <netinet/tcp_log_buf.h> 111 #include <netinet6/tcp6_var.h> 112 #include <netinet/tcpip.h> 113 #include <netinet/cc/cc.h> 114 #include <netinet/tcp_fastopen.h> 115 #ifdef TCPPCAP 116 #include <netinet/tcp_pcap.h> 117 #endif 118 #include <netinet/tcp_syncache.h> 119 #ifdef TCP_OFFLOAD 120 #include <netinet/tcp_offload.h> 121 #endif 122 #include <netinet/tcp_ecn.h> 123 #include <netinet/udp.h> 124 125 #include <netipsec/ipsec_support.h> 126 127 #include <machine/in_cksum.h> 128 129 #include <security/mac/mac_framework.h> 130 131 const int tcprexmtthresh = 3; 132 133 VNET_DEFINE(int, tcp_log_in_vain) = 0; 134 SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_in_vain, CTLFLAG_VNET | CTLFLAG_RW, 135 &VNET_NAME(tcp_log_in_vain), 0, 136 "Log all incoming TCP segments to closed ports"); 137 138 VNET_DEFINE(int, blackhole) = 0; 139 #define V_blackhole VNET(blackhole) 140 SYSCTL_INT(_net_inet_tcp, OID_AUTO, blackhole, CTLFLAG_VNET | CTLFLAG_RW, 141 &VNET_NAME(blackhole), 0, 142 "Do not send RST on segments to closed ports"); 143 144 VNET_DEFINE(bool, blackhole_local) = false; 145 #define V_blackhole_local VNET(blackhole_local) 146 SYSCTL_BOOL(_net_inet_tcp, OID_AUTO, blackhole_local, CTLFLAG_VNET | 147 CTLFLAG_RW, &VNET_NAME(blackhole_local), false, 148 "Enforce net.inet.tcp.blackhole for locally originated packets"); 149 150 VNET_DEFINE(int, tcp_delack_enabled) = 1; 151 SYSCTL_INT(_net_inet_tcp, OID_AUTO, delayed_ack, CTLFLAG_VNET | CTLFLAG_RW, 152 &VNET_NAME(tcp_delack_enabled), 0, 153 "Delay ACK to try and piggyback it onto a data packet"); 154 155 VNET_DEFINE(int, drop_synfin) = 0; 156 SYSCTL_INT(_net_inet_tcp, OID_AUTO, drop_synfin, CTLFLAG_VNET | CTLFLAG_RW, 157 &VNET_NAME(drop_synfin), 0, 158 "Drop TCP packets with SYN+FIN set"); 159 160 VNET_DEFINE(int, tcp_do_prr) = 1; 161 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_prr, CTLFLAG_VNET | CTLFLAG_RW, 162 &VNET_NAME(tcp_do_prr), 1, 163 "Enable Proportional Rate Reduction per RFC 6937"); 164 165 VNET_DEFINE(int, tcp_do_newcwv) = 0; 166 SYSCTL_INT(_net_inet_tcp, OID_AUTO, newcwv, CTLFLAG_VNET | CTLFLAG_RW, 167 &VNET_NAME(tcp_do_newcwv), 0, 168 "Enable New Congestion Window Validation per RFC7661"); 169 170 VNET_DEFINE(int, tcp_do_rfc3042) = 1; 171 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3042, CTLFLAG_VNET | CTLFLAG_RW, 172 &VNET_NAME(tcp_do_rfc3042), 0, 173 "Enable RFC 3042 (Limited Transmit)"); 174 175 VNET_DEFINE(int, tcp_do_rfc3390) = 1; 176 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3390, CTLFLAG_VNET | CTLFLAG_RW, 177 &VNET_NAME(tcp_do_rfc3390), 0, 178 "Enable RFC 3390 (Increasing TCP's Initial Congestion Window)"); 179 180 VNET_DEFINE(int, tcp_initcwnd_segments) = 10; 181 SYSCTL_INT(_net_inet_tcp, OID_AUTO, initcwnd_segments, 182 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(tcp_initcwnd_segments), 0, 183 "Slow-start flight size (initial congestion window) in number of segments"); 184 185 VNET_DEFINE(int, tcp_do_rfc3465) = 1; 186 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3465, CTLFLAG_VNET | CTLFLAG_RW, 187 &VNET_NAME(tcp_do_rfc3465), 0, 188 "Enable RFC 3465 (Appropriate Byte Counting)"); 189 190 VNET_DEFINE(int, tcp_abc_l_var) = 2; 191 SYSCTL_INT(_net_inet_tcp, OID_AUTO, abc_l_var, CTLFLAG_VNET | CTLFLAG_RW, 192 &VNET_NAME(tcp_abc_l_var), 2, 193 "Cap the max cwnd increment during slow-start to this number of segments"); 194 195 VNET_DEFINE(int, tcp_insecure_syn) = 0; 196 SYSCTL_INT(_net_inet_tcp, OID_AUTO, insecure_syn, CTLFLAG_VNET | CTLFLAG_RW, 197 &VNET_NAME(tcp_insecure_syn), 0, 198 "Follow RFC793 instead of RFC5961 criteria for accepting SYN packets"); 199 200 VNET_DEFINE(int, tcp_insecure_rst) = 0; 201 SYSCTL_INT(_net_inet_tcp, OID_AUTO, insecure_rst, CTLFLAG_VNET | CTLFLAG_RW, 202 &VNET_NAME(tcp_insecure_rst), 0, 203 "Follow RFC793 instead of RFC5961 criteria for accepting RST packets"); 204 205 VNET_DEFINE(int, tcp_recvspace) = 1024*64; 206 #define V_tcp_recvspace VNET(tcp_recvspace) 207 SYSCTL_INT(_net_inet_tcp, TCPCTL_RECVSPACE, recvspace, CTLFLAG_VNET | CTLFLAG_RW, 208 &VNET_NAME(tcp_recvspace), 0, "Initial receive socket buffer size"); 209 210 VNET_DEFINE(int, tcp_do_autorcvbuf) = 1; 211 SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_auto, CTLFLAG_VNET | CTLFLAG_RW, 212 &VNET_NAME(tcp_do_autorcvbuf), 0, 213 "Enable automatic receive buffer sizing"); 214 215 VNET_DEFINE(int, tcp_autorcvbuf_max) = 2*1024*1024; 216 SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_max, CTLFLAG_VNET | CTLFLAG_RW, 217 &VNET_NAME(tcp_autorcvbuf_max), 0, 218 "Max size of automatic receive buffer"); 219 220 VNET_DEFINE(struct inpcbinfo, tcbinfo); 221 222 /* 223 * TCP statistics are stored in an array of counter(9)s, which size matches 224 * size of struct tcpstat. TCP running connection count is a regular array. 225 */ 226 VNET_PCPUSTAT_DEFINE(struct tcpstat, tcpstat); 227 SYSCTL_VNET_PCPUSTAT(_net_inet_tcp, TCPCTL_STATS, stats, struct tcpstat, 228 tcpstat, "TCP statistics (struct tcpstat, netinet/tcp_var.h)"); 229 VNET_DEFINE(counter_u64_t, tcps_states[TCP_NSTATES]); 230 SYSCTL_COUNTER_U64_ARRAY(_net_inet_tcp, TCPCTL_STATES, states, CTLFLAG_RD | 231 CTLFLAG_VNET, &VNET_NAME(tcps_states)[0], TCP_NSTATES, 232 "TCP connection counts by TCP state"); 233 234 /* 235 * Kernel module interface for updating tcpstat. The first argument is an index 236 * into tcpstat treated as an array. 237 */ 238 void 239 kmod_tcpstat_add(int statnum, int val) 240 { 241 242 counter_u64_add(VNET(tcpstat)[statnum], val); 243 } 244 245 /* 246 * Make sure that we only start a SACK loss recovery when 247 * receiving a duplicate ACK with a SACK block, and also 248 * complete SACK loss recovery in case the other end 249 * reneges. 250 */ 251 static bool inline 252 tcp_is_sack_recovery(struct tcpcb *tp, struct tcpopt *to) 253 { 254 return ((tp->t_flags & TF_SACK_PERMIT) && 255 ((to->to_flags & TOF_SACK) || 256 (!TAILQ_EMPTY(&tp->snd_holes)))); 257 } 258 259 #ifdef TCP_HHOOK 260 /* 261 * Wrapper for the TCP established input helper hook. 262 */ 263 void 264 hhook_run_tcp_est_in(struct tcpcb *tp, struct tcphdr *th, struct tcpopt *to) 265 { 266 struct tcp_hhook_data hhook_data; 267 268 if (V_tcp_hhh[HHOOK_TCP_EST_IN]->hhh_nhooks > 0) { 269 hhook_data.tp = tp; 270 hhook_data.th = th; 271 hhook_data.to = to; 272 273 hhook_run_hooks(V_tcp_hhh[HHOOK_TCP_EST_IN], &hhook_data, 274 &tp->t_osd); 275 } 276 } 277 #endif 278 279 /* 280 * CC wrapper hook functions 281 */ 282 void 283 cc_ack_received(struct tcpcb *tp, struct tcphdr *th, uint16_t nsegs, 284 uint16_t type) 285 { 286 #ifdef STATS 287 int32_t gput; 288 #endif 289 290 INP_WLOCK_ASSERT(tptoinpcb(tp)); 291 292 tp->t_ccv.nsegs = nsegs; 293 tp->t_ccv.bytes_this_ack = BYTES_THIS_ACK(tp, th); 294 if ((!V_tcp_do_newcwv && (tp->snd_cwnd <= tp->snd_wnd)) || 295 (V_tcp_do_newcwv && (tp->snd_cwnd <= tp->snd_wnd) && 296 (tp->snd_cwnd < (tcp_compute_pipe(tp) * 2)))) 297 tp->t_ccv.flags |= CCF_CWND_LIMITED; 298 else 299 tp->t_ccv.flags &= ~CCF_CWND_LIMITED; 300 301 if (type == CC_ACK) { 302 #ifdef STATS 303 stats_voi_update_abs_s32(tp->t_stats, VOI_TCP_CALCFRWINDIFF, 304 ((int32_t)tp->snd_cwnd) - tp->snd_wnd); 305 if (!IN_RECOVERY(tp->t_flags)) 306 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_ACKLEN, 307 tp->t_ccv.bytes_this_ack / (tcp_maxseg(tp) * nsegs)); 308 if ((tp->t_flags & TF_GPUTINPROG) && 309 SEQ_GEQ(th->th_ack, tp->gput_ack)) { 310 /* 311 * Compute goodput in bits per millisecond. 312 */ 313 gput = (((int64_t)SEQ_SUB(th->th_ack, tp->gput_seq)) << 3) / 314 max(1, tcp_ts_getticks() - tp->gput_ts); 315 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_GPUT, 316 gput); 317 /* 318 * XXXLAS: This is a temporary hack, and should be 319 * chained off VOI_TCP_GPUT when stats(9) grows an API 320 * to deal with chained VOIs. 321 */ 322 if (tp->t_stats_gput_prev > 0) 323 stats_voi_update_abs_s32(tp->t_stats, 324 VOI_TCP_GPUT_ND, 325 ((gput - tp->t_stats_gput_prev) * 100) / 326 tp->t_stats_gput_prev); 327 tp->t_flags &= ~TF_GPUTINPROG; 328 tp->t_stats_gput_prev = gput; 329 } 330 #endif /* STATS */ 331 if (tp->snd_cwnd > tp->snd_ssthresh) { 332 tp->t_bytes_acked += tp->t_ccv.bytes_this_ack; 333 if (tp->t_bytes_acked >= tp->snd_cwnd) { 334 tp->t_bytes_acked -= tp->snd_cwnd; 335 tp->t_ccv.flags |= CCF_ABC_SENTAWND; 336 } 337 } else { 338 tp->t_ccv.flags &= ~CCF_ABC_SENTAWND; 339 tp->t_bytes_acked = 0; 340 } 341 } 342 343 if (CC_ALGO(tp)->ack_received != NULL) { 344 /* XXXLAS: Find a way to live without this */ 345 tp->t_ccv.curack = th->th_ack; 346 CC_ALGO(tp)->ack_received(&tp->t_ccv, type); 347 } 348 #ifdef STATS 349 stats_voi_update_abs_ulong(tp->t_stats, VOI_TCP_LCWIN, tp->snd_cwnd); 350 #endif 351 } 352 353 void 354 cc_conn_init(struct tcpcb *tp) 355 { 356 struct hc_metrics_lite metrics; 357 struct inpcb *inp = tptoinpcb(tp); 358 u_int maxseg; 359 int rtt; 360 361 INP_WLOCK_ASSERT(inp); 362 363 tcp_hc_get(&inp->inp_inc, &metrics); 364 maxseg = tcp_maxseg(tp); 365 366 if (tp->t_srtt == 0 && (rtt = metrics.rmx_rtt)) { 367 tp->t_srtt = rtt; 368 TCPSTAT_INC(tcps_usedrtt); 369 if (metrics.rmx_rttvar) { 370 tp->t_rttvar = metrics.rmx_rttvar; 371 TCPSTAT_INC(tcps_usedrttvar); 372 } else { 373 /* default variation is +- 1 rtt */ 374 tp->t_rttvar = 375 tp->t_srtt * TCP_RTTVAR_SCALE / TCP_RTT_SCALE; 376 } 377 TCPT_RANGESET(tp->t_rxtcur, 378 ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1, 379 tp->t_rttmin, TCPTV_REXMTMAX); 380 } 381 if (metrics.rmx_ssthresh) { 382 /* 383 * There's some sort of gateway or interface 384 * buffer limit on the path. Use this to set 385 * the slow start threshold, but set the 386 * threshold to no less than 2*mss. 387 */ 388 tp->snd_ssthresh = max(2 * maxseg, metrics.rmx_ssthresh); 389 TCPSTAT_INC(tcps_usedssthresh); 390 } 391 392 /* 393 * Set the initial slow-start flight size. 394 * 395 * If a SYN or SYN/ACK was lost and retransmitted, we have to 396 * reduce the initial CWND to one segment as congestion is likely 397 * requiring us to be cautious. 398 */ 399 if (tp->snd_cwnd == 1) 400 tp->snd_cwnd = maxseg; /* SYN(-ACK) lost */ 401 else 402 tp->snd_cwnd = tcp_compute_initwnd(maxseg); 403 404 if (CC_ALGO(tp)->conn_init != NULL) 405 CC_ALGO(tp)->conn_init(&tp->t_ccv); 406 } 407 408 void inline 409 cc_cong_signal(struct tcpcb *tp, struct tcphdr *th, uint32_t type) 410 { 411 INP_WLOCK_ASSERT(tptoinpcb(tp)); 412 413 #ifdef STATS 414 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_CSIG, type); 415 #endif 416 417 switch(type) { 418 case CC_NDUPACK: 419 if (!IN_FASTRECOVERY(tp->t_flags)) { 420 tp->snd_recover = tp->snd_max; 421 if (tp->t_flags2 & TF2_ECN_PERMIT) 422 tp->t_flags2 |= TF2_ECN_SND_CWR; 423 } 424 break; 425 case CC_ECN: 426 if (!IN_CONGRECOVERY(tp->t_flags) || 427 /* 428 * Allow ECN reaction on ACK to CWR, if 429 * that data segment was also CE marked. 430 */ 431 SEQ_GEQ(th->th_ack, tp->snd_recover)) { 432 EXIT_CONGRECOVERY(tp->t_flags); 433 TCPSTAT_INC(tcps_ecn_rcwnd); 434 tp->snd_recover = tp->snd_max + 1; 435 if (tp->t_flags2 & TF2_ECN_PERMIT) 436 tp->t_flags2 |= TF2_ECN_SND_CWR; 437 } 438 break; 439 case CC_RTO: 440 tp->t_dupacks = 0; 441 tp->t_bytes_acked = 0; 442 if ((tp->t_rxtshift > 1) || 443 !((tp->t_flags & TF_SACK_PERMIT) && 444 (!TAILQ_EMPTY(&tp->snd_holes)))) 445 EXIT_RECOVERY(tp->t_flags); 446 if (tp->t_flags2 & TF2_ECN_PERMIT) 447 tp->t_flags2 |= TF2_ECN_SND_CWR; 448 break; 449 case CC_RTO_ERR: 450 TCPSTAT_INC(tcps_sndrexmitbad); 451 /* RTO was unnecessary, so reset everything. */ 452 tp->snd_cwnd = tp->snd_cwnd_prev; 453 tp->snd_ssthresh = tp->snd_ssthresh_prev; 454 tp->snd_recover = tp->snd_recover_prev; 455 if (tp->t_flags & TF_WASFRECOVERY) 456 ENTER_FASTRECOVERY(tp->t_flags); 457 if (tp->t_flags & TF_WASCRECOVERY) 458 ENTER_CONGRECOVERY(tp->t_flags); 459 tp->snd_nxt = tp->snd_max; 460 tp->t_flags &= ~TF_PREVVALID; 461 tp->t_badrxtwin = 0; 462 break; 463 } 464 465 if (CC_ALGO(tp)->cong_signal != NULL) { 466 if (th != NULL) 467 tp->t_ccv.curack = th->th_ack; 468 CC_ALGO(tp)->cong_signal(&tp->t_ccv, type); 469 } 470 } 471 472 void inline 473 cc_post_recovery(struct tcpcb *tp, struct tcphdr *th) 474 { 475 INP_WLOCK_ASSERT(tptoinpcb(tp)); 476 477 /* XXXLAS: KASSERT that we're in recovery? */ 478 479 if (CC_ALGO(tp)->post_recovery != NULL) { 480 tp->t_ccv.curack = th->th_ack; 481 CC_ALGO(tp)->post_recovery(&tp->t_ccv); 482 } 483 /* XXXLAS: EXIT_RECOVERY ? */ 484 tp->t_bytes_acked = 0; 485 tp->sackhint.delivered_data = 0; 486 tp->sackhint.prr_delivered = 0; 487 tp->sackhint.prr_out = 0; 488 } 489 490 /* 491 * Indicate whether this ack should be delayed. We can delay the ack if 492 * following conditions are met: 493 * - There is no delayed ack timer in progress. 494 * - Our last ack wasn't a 0-sized window. We never want to delay 495 * the ack that opens up a 0-sized window. 496 * - LRO wasn't used for this segment. We make sure by checking that the 497 * segment size is not larger than the MSS. 498 */ 499 #define DELAY_ACK(tp, tlen) \ 500 ((!tcp_timer_active(tp, TT_DELACK) && \ 501 (tp->t_flags & TF_RXWIN0SENT) == 0) && \ 502 (tlen <= tp->t_maxseg) && \ 503 (V_tcp_delack_enabled || (tp->t_flags & TF_NEEDSYN))) 504 505 void inline 506 cc_ecnpkt_handler_flags(struct tcpcb *tp, uint16_t flags, uint8_t iptos) 507 { 508 INP_WLOCK_ASSERT(tptoinpcb(tp)); 509 510 if (CC_ALGO(tp)->ecnpkt_handler != NULL) { 511 switch (iptos & IPTOS_ECN_MASK) { 512 case IPTOS_ECN_CE: 513 tp->t_ccv.flags |= CCF_IPHDR_CE; 514 break; 515 case IPTOS_ECN_ECT0: 516 /* FALLTHROUGH */ 517 case IPTOS_ECN_ECT1: 518 /* FALLTHROUGH */ 519 case IPTOS_ECN_NOTECT: 520 tp->t_ccv.flags &= ~CCF_IPHDR_CE; 521 break; 522 } 523 524 if (flags & TH_CWR) 525 tp->t_ccv.flags |= CCF_TCPHDR_CWR; 526 else 527 tp->t_ccv.flags &= ~CCF_TCPHDR_CWR; 528 529 CC_ALGO(tp)->ecnpkt_handler(&tp->t_ccv); 530 531 if (tp->t_ccv.flags & CCF_ACKNOW) { 532 tcp_timer_activate(tp, TT_DELACK, tcp_delacktime); 533 tp->t_flags |= TF_ACKNOW; 534 } 535 } 536 } 537 538 void inline 539 cc_ecnpkt_handler(struct tcpcb *tp, struct tcphdr *th, uint8_t iptos) 540 { 541 cc_ecnpkt_handler_flags(tp, tcp_get_flags(th), iptos); 542 } 543 544 /* 545 * TCP input handling is split into multiple parts: 546 * tcp6_input is a thin wrapper around tcp_input for the extended 547 * ip6_protox[] call format in ip6_input 548 * tcp_input handles primary segment validation, inpcb lookup and 549 * SYN processing on listen sockets 550 * tcp_do_segment processes the ACK and text of the segment for 551 * establishing, established and closing connections 552 */ 553 #ifdef INET6 554 int 555 tcp6_input_with_port(struct mbuf **mp, int *offp, int proto, uint16_t port) 556 { 557 struct mbuf *m; 558 struct in6_ifaddr *ia6; 559 struct ip6_hdr *ip6; 560 561 m = *mp; 562 if (m->m_len < *offp + sizeof(struct tcphdr)) { 563 m = m_pullup(m, *offp + sizeof(struct tcphdr)); 564 if (m == NULL) { 565 *mp = m; 566 TCPSTAT_INC(tcps_rcvshort); 567 return (IPPROTO_DONE); 568 } 569 } 570 571 /* 572 * draft-itojun-ipv6-tcp-to-anycast 573 * better place to put this in? 574 */ 575 ip6 = mtod(m, struct ip6_hdr *); 576 ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */, false); 577 if (ia6 && (ia6->ia6_flags & IN6_IFF_ANYCAST)) { 578 icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR, 579 (caddr_t)&ip6->ip6_dst - (caddr_t)ip6); 580 *mp = NULL; 581 return (IPPROTO_DONE); 582 } 583 584 *mp = m; 585 return (tcp_input_with_port(mp, offp, proto, port)); 586 } 587 588 int 589 tcp6_input(struct mbuf **mp, int *offp, int proto) 590 { 591 592 return(tcp6_input_with_port(mp, offp, proto, 0)); 593 } 594 #endif /* INET6 */ 595 596 int 597 tcp_input_with_port(struct mbuf **mp, int *offp, int proto, uint16_t port) 598 { 599 struct mbuf *m = *mp; 600 struct tcphdr *th = NULL; 601 struct ip *ip = NULL; 602 struct inpcb *inp = NULL; 603 struct tcpcb *tp = NULL; 604 struct socket *so = NULL; 605 u_char *optp = NULL; 606 int off0; 607 int optlen = 0; 608 #ifdef INET 609 int len; 610 uint8_t ipttl; 611 #endif 612 int tlen = 0, off; 613 int drop_hdrlen; 614 int thflags; 615 int rstreason = 0; /* For badport_bandlim accounting purposes */ 616 int lookupflag; 617 uint8_t iptos; 618 struct m_tag *fwd_tag = NULL; 619 #ifdef INET6 620 struct ip6_hdr *ip6 = NULL; 621 int isipv6; 622 #else 623 const void *ip6 = NULL; 624 #endif /* INET6 */ 625 struct tcpopt to; /* options in this segment */ 626 char *s = NULL; /* address and port logging */ 627 628 NET_EPOCH_ASSERT(); 629 630 #ifdef INET6 631 isipv6 = (mtod(m, struct ip *)->ip_v == 6) ? 1 : 0; 632 #endif 633 634 off0 = *offp; 635 m = *mp; 636 *mp = NULL; 637 to.to_flags = 0; 638 TCPSTAT_INC(tcps_rcvtotal); 639 640 m->m_pkthdr.tcp_tun_port = port; 641 #ifdef INET6 642 if (isipv6) { 643 ip6 = mtod(m, struct ip6_hdr *); 644 th = (struct tcphdr *)((caddr_t)ip6 + off0); 645 tlen = sizeof(*ip6) + ntohs(ip6->ip6_plen) - off0; 646 if (port) 647 goto skip6_csum; 648 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID_IPV6) { 649 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 650 th->th_sum = m->m_pkthdr.csum_data; 651 else 652 th->th_sum = in6_cksum_pseudo(ip6, tlen, 653 IPPROTO_TCP, m->m_pkthdr.csum_data); 654 th->th_sum ^= 0xffff; 655 } else 656 th->th_sum = in6_cksum(m, IPPROTO_TCP, off0, tlen); 657 if (th->th_sum) { 658 TCPSTAT_INC(tcps_rcvbadsum); 659 goto drop; 660 } 661 skip6_csum: 662 /* 663 * Be proactive about unspecified IPv6 address in source. 664 * As we use all-zero to indicate unbounded/unconnected pcb, 665 * unspecified IPv6 address can be used to confuse us. 666 * 667 * Note that packets with unspecified IPv6 destination is 668 * already dropped in ip6_input. 669 */ 670 KASSERT(!IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_dst), 671 ("%s: unspecified destination v6 address", __func__)); 672 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 673 IP6STAT_INC(ip6s_badscope); /* XXX */ 674 goto drop; 675 } 676 iptos = IPV6_TRAFFIC_CLASS(ip6); 677 } 678 #endif 679 #if defined(INET) && defined(INET6) 680 else 681 #endif 682 #ifdef INET 683 { 684 /* 685 * Get IP and TCP header together in first mbuf. 686 * Note: IP leaves IP header in first mbuf. 687 */ 688 if (off0 > sizeof (struct ip)) { 689 ip_stripoptions(m); 690 off0 = sizeof(struct ip); 691 } 692 if (m->m_len < sizeof (struct tcpiphdr)) { 693 if ((m = m_pullup(m, sizeof (struct tcpiphdr))) 694 == NULL) { 695 TCPSTAT_INC(tcps_rcvshort); 696 return (IPPROTO_DONE); 697 } 698 } 699 ip = mtod(m, struct ip *); 700 th = (struct tcphdr *)((caddr_t)ip + off0); 701 tlen = ntohs(ip->ip_len) - off0; 702 703 iptos = ip->ip_tos; 704 if (port) 705 goto skip_csum; 706 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) { 707 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 708 th->th_sum = m->m_pkthdr.csum_data; 709 else 710 th->th_sum = in_pseudo(ip->ip_src.s_addr, 711 ip->ip_dst.s_addr, 712 htonl(m->m_pkthdr.csum_data + tlen + 713 IPPROTO_TCP)); 714 th->th_sum ^= 0xffff; 715 } else { 716 struct ipovly *ipov = (struct ipovly *)ip; 717 718 /* 719 * Checksum extended TCP header and data. 720 */ 721 len = off0 + tlen; 722 ipttl = ip->ip_ttl; 723 bzero(ipov->ih_x1, sizeof(ipov->ih_x1)); 724 ipov->ih_len = htons(tlen); 725 th->th_sum = in_cksum(m, len); 726 /* Reset length for SDT probes. */ 727 ip->ip_len = htons(len); 728 /* Reset TOS bits */ 729 ip->ip_tos = iptos; 730 /* Re-initialization for later version check */ 731 ip->ip_ttl = ipttl; 732 ip->ip_v = IPVERSION; 733 ip->ip_hl = off0 >> 2; 734 } 735 skip_csum: 736 if (th->th_sum && (port == 0)) { 737 TCPSTAT_INC(tcps_rcvbadsum); 738 goto drop; 739 } 740 KASSERT(ip->ip_dst.s_addr != INADDR_ANY, 741 ("%s: unspecified destination v4 address", __func__)); 742 if (__predict_false(ip->ip_src.s_addr == INADDR_ANY)) { 743 IPSTAT_INC(ips_badaddr); 744 goto drop; 745 } 746 } 747 #endif /* INET */ 748 749 /* 750 * Check that TCP offset makes sense, 751 * pull out TCP options and adjust length. XXX 752 */ 753 off = th->th_off << 2; 754 if (off < sizeof (struct tcphdr) || off > tlen) { 755 TCPSTAT_INC(tcps_rcvbadoff); 756 goto drop; 757 } 758 tlen -= off; /* tlen is used instead of ti->ti_len */ 759 if (off > sizeof (struct tcphdr)) { 760 #ifdef INET6 761 if (isipv6) { 762 if (m->m_len < off0 + off) { 763 m = m_pullup(m, off0 + off); 764 if (m == NULL) { 765 TCPSTAT_INC(tcps_rcvshort); 766 return (IPPROTO_DONE); 767 } 768 } 769 ip6 = mtod(m, struct ip6_hdr *); 770 th = (struct tcphdr *)((caddr_t)ip6 + off0); 771 } 772 #endif 773 #if defined(INET) && defined(INET6) 774 else 775 #endif 776 #ifdef INET 777 { 778 if (m->m_len < sizeof(struct ip) + off) { 779 if ((m = m_pullup(m, sizeof (struct ip) + off)) 780 == NULL) { 781 TCPSTAT_INC(tcps_rcvshort); 782 return (IPPROTO_DONE); 783 } 784 ip = mtod(m, struct ip *); 785 th = (struct tcphdr *)((caddr_t)ip + off0); 786 } 787 } 788 #endif 789 optlen = off - sizeof (struct tcphdr); 790 optp = (u_char *)(th + 1); 791 } 792 thflags = tcp_get_flags(th); 793 794 /* 795 * Convert TCP protocol specific fields to host format. 796 */ 797 tcp_fields_to_host(th); 798 799 /* 800 * Delay dropping TCP, IP headers, IPv6 ext headers, and TCP options. 801 */ 802 drop_hdrlen = off0 + off; 803 804 /* 805 * Grab info from PACKET_TAG_IPFORWARD tag prepended to the chain. 806 */ 807 if ( 808 #ifdef INET6 809 (isipv6 && (m->m_flags & M_IP6_NEXTHOP)) 810 #ifdef INET 811 || (!isipv6 && (m->m_flags & M_IP_NEXTHOP)) 812 #endif 813 #endif 814 #if defined(INET) && !defined(INET6) 815 (m->m_flags & M_IP_NEXTHOP) 816 #endif 817 ) 818 fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL); 819 820 /* 821 * For initial SYN packets we don't need write lock on matching 822 * PCB, be it a listening one or a synchronized one. The packet 823 * shall not modify its state. 824 */ 825 lookupflag = INPLOOKUP_WILDCARD | 826 ((thflags & (TH_ACK|TH_SYN)) == TH_SYN ? 827 INPLOOKUP_RLOCKPCB : INPLOOKUP_WLOCKPCB); 828 findpcb: 829 #ifdef INET6 830 if (isipv6 && fwd_tag != NULL) { 831 struct sockaddr_in6 *next_hop6; 832 833 next_hop6 = (struct sockaddr_in6 *)(fwd_tag + 1); 834 /* 835 * Transparently forwarded. Pretend to be the destination. 836 * Already got one like this? 837 */ 838 inp = in6_pcblookup_mbuf(&V_tcbinfo, 839 &ip6->ip6_src, th->th_sport, &ip6->ip6_dst, th->th_dport, 840 lookupflag & ~INPLOOKUP_WILDCARD, m->m_pkthdr.rcvif, m); 841 if (!inp) { 842 /* 843 * It's new. Try to find the ambushing socket. 844 * Because we've rewritten the destination address, 845 * any hardware-generated hash is ignored. 846 */ 847 inp = in6_pcblookup(&V_tcbinfo, &ip6->ip6_src, 848 th->th_sport, &next_hop6->sin6_addr, 849 next_hop6->sin6_port ? ntohs(next_hop6->sin6_port) : 850 th->th_dport, lookupflag, m->m_pkthdr.rcvif); 851 } 852 } else if (isipv6) { 853 inp = in6_pcblookup_mbuf(&V_tcbinfo, &ip6->ip6_src, 854 th->th_sport, &ip6->ip6_dst, th->th_dport, lookupflag, 855 m->m_pkthdr.rcvif, m); 856 } 857 #endif /* INET6 */ 858 #if defined(INET6) && defined(INET) 859 else 860 #endif 861 #ifdef INET 862 if (fwd_tag != NULL) { 863 struct sockaddr_in *next_hop; 864 865 next_hop = (struct sockaddr_in *)(fwd_tag+1); 866 /* 867 * Transparently forwarded. Pretend to be the destination. 868 * already got one like this? 869 */ 870 inp = in_pcblookup_mbuf(&V_tcbinfo, ip->ip_src, th->th_sport, 871 ip->ip_dst, th->th_dport, lookupflag & ~INPLOOKUP_WILDCARD, 872 m->m_pkthdr.rcvif, m); 873 if (!inp) { 874 /* 875 * It's new. Try to find the ambushing socket. 876 * Because we've rewritten the destination address, 877 * any hardware-generated hash is ignored. 878 */ 879 inp = in_pcblookup(&V_tcbinfo, ip->ip_src, 880 th->th_sport, next_hop->sin_addr, 881 next_hop->sin_port ? ntohs(next_hop->sin_port) : 882 th->th_dport, lookupflag, m->m_pkthdr.rcvif); 883 } 884 } else 885 inp = in_pcblookup_mbuf(&V_tcbinfo, ip->ip_src, 886 th->th_sport, ip->ip_dst, th->th_dport, lookupflag, 887 m->m_pkthdr.rcvif, m); 888 #endif /* INET */ 889 890 /* 891 * If the INPCB does not exist then all data in the incoming 892 * segment is discarded and an appropriate RST is sent back. 893 * XXX MRT Send RST using which routing table? 894 */ 895 if (inp == NULL) { 896 if (rstreason != 0) { 897 /* We came here after second (safety) lookup. */ 898 MPASS((lookupflag & INPLOOKUP_WILDCARD) == 0); 899 goto dropwithreset; 900 } 901 /* 902 * Log communication attempts to ports that are not 903 * in use. 904 */ 905 if ((V_tcp_log_in_vain == 1 && (thflags & TH_SYN)) || 906 V_tcp_log_in_vain == 2) { 907 if ((s = tcp_log_vain(NULL, th, (void *)ip, ip6))) 908 log(LOG_INFO, "%s; %s: Connection attempt " 909 "to closed port\n", s, __func__); 910 } 911 /* 912 * When blackholing do not respond with a RST but 913 * completely ignore the segment and drop it. 914 */ 915 if (((V_blackhole == 1 && (thflags & TH_SYN)) || 916 V_blackhole == 2) && (V_blackhole_local || ( 917 #ifdef INET6 918 isipv6 ? !in6_localaddr(&ip6->ip6_src) : 919 #endif 920 #ifdef INET 921 !in_localip(ip->ip_src) 922 #else 923 true 924 #endif 925 ))) 926 goto dropunlock; 927 928 rstreason = BANDLIM_RST_CLOSEDPORT; 929 goto dropwithreset; 930 } 931 INP_LOCK_ASSERT(inp); 932 933 if ((inp->inp_flowtype == M_HASHTYPE_NONE) && 934 !SOLISTENING(inp->inp_socket)) { 935 if (M_HASHTYPE_GET(m) != M_HASHTYPE_NONE) { 936 inp->inp_flowid = m->m_pkthdr.flowid; 937 inp->inp_flowtype = M_HASHTYPE_GET(m); 938 #ifdef RSS 939 } else { 940 /* assign flowid by software RSS hash */ 941 #ifdef INET6 942 if (isipv6) { 943 rss_proto_software_hash_v6(&inp->in6p_faddr, 944 &inp->in6p_laddr, 945 inp->inp_fport, 946 inp->inp_lport, 947 IPPROTO_TCP, 948 &inp->inp_flowid, 949 &inp->inp_flowtype); 950 } else 951 #endif /* INET6 */ 952 { 953 rss_proto_software_hash_v4(inp->inp_faddr, 954 inp->inp_laddr, 955 inp->inp_fport, 956 inp->inp_lport, 957 IPPROTO_TCP, 958 &inp->inp_flowid, 959 &inp->inp_flowtype); 960 } 961 #endif /* RSS */ 962 } 963 } 964 #if defined(IPSEC) || defined(IPSEC_SUPPORT) 965 #ifdef INET6 966 if (isipv6 && IPSEC_ENABLED(ipv6) && 967 IPSEC_CHECK_POLICY(ipv6, m, inp) != 0) { 968 goto dropunlock; 969 } 970 #ifdef INET 971 else 972 #endif 973 #endif /* INET6 */ 974 #ifdef INET 975 if (IPSEC_ENABLED(ipv4) && 976 IPSEC_CHECK_POLICY(ipv4, m, inp) != 0) { 977 goto dropunlock; 978 } 979 #endif /* INET */ 980 #endif /* IPSEC */ 981 982 /* 983 * Check the minimum TTL for socket. 984 */ 985 if (inp->inp_ip_minttl != 0) { 986 #ifdef INET6 987 if (isipv6) { 988 if (inp->inp_ip_minttl > ip6->ip6_hlim) 989 goto dropunlock; 990 } else 991 #endif 992 if (inp->inp_ip_minttl > ip->ip_ttl) 993 goto dropunlock; 994 } 995 996 tp = intotcpcb(inp); 997 switch (tp->t_state) { 998 case TCPS_TIME_WAIT: 999 /* 1000 * A previous connection in TIMEWAIT state is supposed to catch 1001 * stray or duplicate segments arriving late. If this segment 1002 * was a legitimate new connection attempt, the old INPCB gets 1003 * removed and we can try again to find a listening socket. 1004 */ 1005 tcp_dooptions(&to, optp, optlen, 1006 (thflags & TH_SYN) ? TO_SYN : 0); 1007 /* 1008 * tcp_twcheck unlocks the inp always, and frees the m if fails. 1009 */ 1010 if (tcp_twcheck(inp, &to, th, m, tlen)) 1011 goto findpcb; 1012 return (IPPROTO_DONE); 1013 case TCPS_CLOSED: 1014 /* 1015 * The TCPCB may no longer exist if the connection is winding 1016 * down or it is in the CLOSED state. Either way we drop the 1017 * segment and send an appropriate response. 1018 */ 1019 rstreason = BANDLIM_RST_CLOSEDPORT; 1020 goto dropwithreset; 1021 } 1022 1023 if ((tp->t_port != port) && (tp->t_state > TCPS_LISTEN)) { 1024 rstreason = BANDLIM_RST_CLOSEDPORT; 1025 goto dropwithreset; 1026 } 1027 1028 #ifdef TCP_OFFLOAD 1029 if (tp->t_flags & TF_TOE) { 1030 tcp_offload_input(tp, m); 1031 m = NULL; /* consumed by the TOE driver */ 1032 goto dropunlock; 1033 } 1034 #endif 1035 1036 #ifdef MAC 1037 if (mac_inpcb_check_deliver(inp, m)) 1038 goto dropunlock; 1039 #endif 1040 so = inp->inp_socket; 1041 KASSERT(so != NULL, ("%s: so == NULL", __func__)); 1042 /* 1043 * When the socket is accepting connections (the INPCB is in LISTEN 1044 * state) we look into the SYN cache if this is a new connection 1045 * attempt or the completion of a previous one. 1046 */ 1047 KASSERT(tp->t_state == TCPS_LISTEN || !SOLISTENING(so), 1048 ("%s: so accepting but tp %p not listening", __func__, tp)); 1049 if (tp->t_state == TCPS_LISTEN && SOLISTENING(so)) { 1050 struct in_conninfo inc; 1051 1052 bzero(&inc, sizeof(inc)); 1053 #ifdef INET6 1054 if (isipv6) { 1055 inc.inc_flags |= INC_ISIPV6; 1056 if (inp->inp_inc.inc_flags & INC_IPV6MINMTU) 1057 inc.inc_flags |= INC_IPV6MINMTU; 1058 inc.inc6_faddr = ip6->ip6_src; 1059 inc.inc6_laddr = ip6->ip6_dst; 1060 } else 1061 #endif 1062 { 1063 inc.inc_faddr = ip->ip_src; 1064 inc.inc_laddr = ip->ip_dst; 1065 } 1066 inc.inc_fport = th->th_sport; 1067 inc.inc_lport = th->th_dport; 1068 inc.inc_fibnum = so->so_fibnum; 1069 1070 /* 1071 * Check for an existing connection attempt in syncache if 1072 * the flag is only ACK. A successful lookup creates a new 1073 * socket appended to the listen queue in SYN_RECEIVED state. 1074 */ 1075 if ((thflags & (TH_RST|TH_ACK|TH_SYN)) == TH_ACK) { 1076 /* 1077 * Parse the TCP options here because 1078 * syncookies need access to the reflected 1079 * timestamp. 1080 */ 1081 tcp_dooptions(&to, optp, optlen, 0); 1082 /* 1083 * NB: syncache_expand() doesn't unlock inp. 1084 */ 1085 rstreason = syncache_expand(&inc, &to, th, &so, m, port); 1086 if (rstreason < 0) { 1087 /* 1088 * A failing TCP MD5 signature comparison 1089 * must result in the segment being dropped 1090 * and must not produce any response back 1091 * to the sender. 1092 */ 1093 goto dropunlock; 1094 } else if (rstreason == 0) { 1095 /* 1096 * No syncache entry, or ACK was not for our 1097 * SYN/ACK. Do our protection against double 1098 * ACK. If peer sent us 2 ACKs, then for the 1099 * first one syncache_expand() successfully 1100 * converted syncache entry into a socket, 1101 * while we were waiting on the inpcb lock. We 1102 * don't want to sent RST for the second ACK, 1103 * so we perform second lookup without wildcard 1104 * match, hoping to find the new socket. If 1105 * the ACK is stray indeed, rstreason would 1106 * hint the above code that the lookup was a 1107 * second attempt. 1108 * 1109 * NB: syncache did its own logging 1110 * of the failure cause. 1111 */ 1112 INP_WUNLOCK(inp); 1113 rstreason = BANDLIM_RST_OPENPORT; 1114 lookupflag &= ~INPLOOKUP_WILDCARD; 1115 goto findpcb; 1116 } 1117 tfo_socket_result: 1118 if (so == NULL) { 1119 /* 1120 * We completed the 3-way handshake 1121 * but could not allocate a socket 1122 * either due to memory shortage, 1123 * listen queue length limits or 1124 * global socket limits. Send RST 1125 * or wait and have the remote end 1126 * retransmit the ACK for another 1127 * try. 1128 */ 1129 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1130 log(LOG_DEBUG, "%s; %s: Listen socket: " 1131 "Socket allocation failed due to " 1132 "limits or memory shortage, %s\n", 1133 s, __func__, 1134 V_tcp_sc_rst_sock_fail ? 1135 "sending RST" : "try again"); 1136 if (V_tcp_sc_rst_sock_fail) { 1137 rstreason = BANDLIM_UNLIMITED; 1138 goto dropwithreset; 1139 } else 1140 goto dropunlock; 1141 } 1142 /* 1143 * Socket is created in state SYN_RECEIVED. 1144 * Unlock the listen socket, lock the newly 1145 * created socket and update the tp variable. 1146 * If we came here via jump to tfo_socket_result, 1147 * then listening socket is read-locked. 1148 */ 1149 INP_UNLOCK(inp); /* listen socket */ 1150 inp = sotoinpcb(so); 1151 /* 1152 * New connection inpcb is already locked by 1153 * syncache_expand(). 1154 */ 1155 INP_WLOCK_ASSERT(inp); 1156 tp = intotcpcb(inp); 1157 KASSERT(tp->t_state == TCPS_SYN_RECEIVED, 1158 ("%s: ", __func__)); 1159 /* 1160 * Process the segment and the data it 1161 * contains. tcp_do_segment() consumes 1162 * the mbuf chain and unlocks the inpcb. 1163 */ 1164 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1165 tp->t_fb->tfb_tcp_do_segment(tp, m, th, drop_hdrlen, 1166 tlen, iptos); 1167 return (IPPROTO_DONE); 1168 } 1169 /* 1170 * Segment flag validation for new connection attempts: 1171 * 1172 * Our (SYN|ACK) response was rejected. 1173 * Check with syncache and remove entry to prevent 1174 * retransmits. 1175 * 1176 * NB: syncache_chkrst does its own logging of failure 1177 * causes. 1178 */ 1179 if (thflags & TH_RST) { 1180 syncache_chkrst(&inc, th, m, port); 1181 goto dropunlock; 1182 } 1183 /* 1184 * We can't do anything without SYN. 1185 */ 1186 if ((thflags & TH_SYN) == 0) { 1187 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1188 log(LOG_DEBUG, "%s; %s: Listen socket: " 1189 "SYN is missing, segment ignored\n", 1190 s, __func__); 1191 TCPSTAT_INC(tcps_badsyn); 1192 goto dropunlock; 1193 } 1194 /* 1195 * (SYN|ACK) is bogus on a listen socket. 1196 */ 1197 if (thflags & TH_ACK) { 1198 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1199 log(LOG_DEBUG, "%s; %s: Listen socket: " 1200 "SYN|ACK invalid, segment rejected\n", 1201 s, __func__); 1202 syncache_badack(&inc, port); /* XXX: Not needed! */ 1203 TCPSTAT_INC(tcps_badsyn); 1204 rstreason = BANDLIM_RST_OPENPORT; 1205 goto dropwithreset; 1206 } 1207 /* 1208 * If the drop_synfin option is enabled, drop all 1209 * segments with both the SYN and FIN bits set. 1210 * This prevents e.g. nmap from identifying the 1211 * TCP/IP stack. 1212 * XXX: Poor reasoning. nmap has other methods 1213 * and is constantly refining its stack detection 1214 * strategies. 1215 * XXX: This is a violation of the TCP specification 1216 * and was used by RFC1644. 1217 */ 1218 if ((thflags & TH_FIN) && V_drop_synfin) { 1219 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1220 log(LOG_DEBUG, "%s; %s: Listen socket: " 1221 "SYN|FIN segment ignored (based on " 1222 "sysctl setting)\n", s, __func__); 1223 TCPSTAT_INC(tcps_badsyn); 1224 goto dropunlock; 1225 } 1226 /* 1227 * Segment's flags are (SYN) or (SYN|FIN). 1228 * 1229 * TH_PUSH, TH_URG, TH_ECE, TH_CWR are ignored 1230 * as they do not affect the state of the TCP FSM. 1231 * The data pointed to by TH_URG and th_urp is ignored. 1232 */ 1233 KASSERT((thflags & (TH_RST|TH_ACK)) == 0, 1234 ("%s: Listen socket: TH_RST or TH_ACK set", __func__)); 1235 KASSERT(thflags & (TH_SYN), 1236 ("%s: Listen socket: TH_SYN not set", __func__)); 1237 INP_RLOCK_ASSERT(inp); 1238 #ifdef INET6 1239 /* 1240 * If deprecated address is forbidden, 1241 * we do not accept SYN to deprecated interface 1242 * address to prevent any new inbound connection from 1243 * getting established. 1244 * When we do not accept SYN, we send a TCP RST, 1245 * with deprecated source address (instead of dropping 1246 * it). We compromise it as it is much better for peer 1247 * to send a RST, and RST will be the final packet 1248 * for the exchange. 1249 * 1250 * If we do not forbid deprecated addresses, we accept 1251 * the SYN packet. RFC2462 does not suggest dropping 1252 * SYN in this case. 1253 * If we decipher RFC2462 5.5.4, it says like this: 1254 * 1. use of deprecated addr with existing 1255 * communication is okay - "SHOULD continue to be 1256 * used" 1257 * 2. use of it with new communication: 1258 * (2a) "SHOULD NOT be used if alternate address 1259 * with sufficient scope is available" 1260 * (2b) nothing mentioned otherwise. 1261 * Here we fall into (2b) case as we have no choice in 1262 * our source address selection - we must obey the peer. 1263 * 1264 * The wording in RFC2462 is confusing, and there are 1265 * multiple description text for deprecated address 1266 * handling - worse, they are not exactly the same. 1267 * I believe 5.5.4 is the best one, so we follow 5.5.4. 1268 */ 1269 if (isipv6 && !V_ip6_use_deprecated) { 1270 struct in6_ifaddr *ia6; 1271 1272 ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */, false); 1273 if (ia6 != NULL && 1274 (ia6->ia6_flags & IN6_IFF_DEPRECATED)) { 1275 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1276 log(LOG_DEBUG, "%s; %s: Listen socket: " 1277 "Connection attempt to deprecated " 1278 "IPv6 address rejected\n", 1279 s, __func__); 1280 rstreason = BANDLIM_RST_OPENPORT; 1281 goto dropwithreset; 1282 } 1283 } 1284 #endif /* INET6 */ 1285 /* 1286 * Basic sanity checks on incoming SYN requests: 1287 * Don't respond if the destination is a link layer 1288 * broadcast according to RFC1122 4.2.3.10, p. 104. 1289 * If it is from this socket it must be forged. 1290 * Don't respond if the source or destination is a 1291 * global or subnet broad- or multicast address. 1292 * Note that it is quite possible to receive unicast 1293 * link-layer packets with a broadcast IP address. Use 1294 * in_broadcast() to find them. 1295 */ 1296 if (m->m_flags & (M_BCAST|M_MCAST)) { 1297 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1298 log(LOG_DEBUG, "%s; %s: Listen socket: " 1299 "Connection attempt from broad- or multicast " 1300 "link layer address ignored\n", s, __func__); 1301 goto dropunlock; 1302 } 1303 #ifdef INET6 1304 if (isipv6) { 1305 if (th->th_dport == th->th_sport && 1306 IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &ip6->ip6_src)) { 1307 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1308 log(LOG_DEBUG, "%s; %s: Listen socket: " 1309 "Connection attempt to/from self " 1310 "ignored\n", s, __func__); 1311 goto dropunlock; 1312 } 1313 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 1314 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) { 1315 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1316 log(LOG_DEBUG, "%s; %s: Listen socket: " 1317 "Connection attempt from/to multicast " 1318 "address ignored\n", s, __func__); 1319 goto dropunlock; 1320 } 1321 } 1322 #endif 1323 #if defined(INET) && defined(INET6) 1324 else 1325 #endif 1326 #ifdef INET 1327 { 1328 if (th->th_dport == th->th_sport && 1329 ip->ip_dst.s_addr == ip->ip_src.s_addr) { 1330 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1331 log(LOG_DEBUG, "%s; %s: Listen socket: " 1332 "Connection attempt from/to self " 1333 "ignored\n", s, __func__); 1334 goto dropunlock; 1335 } 1336 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || 1337 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 1338 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || 1339 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) { 1340 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1341 log(LOG_DEBUG, "%s; %s: Listen socket: " 1342 "Connection attempt from/to broad- " 1343 "or multicast address ignored\n", 1344 s, __func__); 1345 goto dropunlock; 1346 } 1347 } 1348 #endif 1349 /* 1350 * SYN appears to be valid. Create compressed TCP state 1351 * for syncache. 1352 */ 1353 TCP_PROBE3(debug__input, tp, th, m); 1354 tcp_dooptions(&to, optp, optlen, TO_SYN); 1355 if ((so = syncache_add(&inc, &to, th, inp, so, m, NULL, NULL, 1356 iptos, port)) != NULL) 1357 goto tfo_socket_result; 1358 1359 /* 1360 * Entry added to syncache and mbuf consumed. 1361 * Only the listen socket is unlocked by syncache_add(). 1362 */ 1363 return (IPPROTO_DONE); 1364 } else if (tp->t_state == TCPS_LISTEN) { 1365 /* 1366 * When a listen socket is torn down the SO_ACCEPTCONN 1367 * flag is removed first while connections are drained 1368 * from the accept queue in a unlock/lock cycle of the 1369 * ACCEPT_LOCK, opening a race condition allowing a SYN 1370 * attempt go through unhandled. 1371 */ 1372 goto dropunlock; 1373 } 1374 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 1375 if (tp->t_flags & TF_SIGNATURE) { 1376 tcp_dooptions(&to, optp, optlen, thflags); 1377 if ((to.to_flags & TOF_SIGNATURE) == 0) { 1378 TCPSTAT_INC(tcps_sig_err_nosigopt); 1379 goto dropunlock; 1380 } 1381 if (!TCPMD5_ENABLED() || 1382 TCPMD5_INPUT(m, th, to.to_signature) != 0) 1383 goto dropunlock; 1384 } 1385 #endif 1386 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1387 1388 /* 1389 * Segment belongs to a connection in SYN_SENT, ESTABLISHED or later 1390 * state. tcp_do_segment() always consumes the mbuf chain, unlocks 1391 * the inpcb, and unlocks pcbinfo. 1392 * 1393 * XXXGL: in case of a pure SYN arriving on existing connection 1394 * TCP stacks won't need to modify the PCB, they would either drop 1395 * the segment silently, or send a challenge ACK. However, we try 1396 * to upgrade the lock, because calling convention for stacks is 1397 * write-lock on PCB. If upgrade fails, drop the SYN. 1398 */ 1399 if ((lookupflag & INPLOOKUP_RLOCKPCB) && INP_TRY_UPGRADE(inp) == 0) 1400 goto dropunlock; 1401 1402 tp->t_fb->tfb_tcp_do_segment(tp, m, th, drop_hdrlen, tlen, iptos); 1403 return (IPPROTO_DONE); 1404 1405 dropwithreset: 1406 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1407 1408 if (inp != NULL) { 1409 tcp_dropwithreset(m, th, tp, tlen, rstreason); 1410 INP_UNLOCK(inp); 1411 } else 1412 tcp_dropwithreset(m, th, NULL, tlen, rstreason); 1413 m = NULL; /* mbuf chain got consumed. */ 1414 goto drop; 1415 1416 dropunlock: 1417 if (m != NULL) 1418 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1419 1420 if (inp != NULL) 1421 INP_UNLOCK(inp); 1422 1423 drop: 1424 if (s != NULL) 1425 free(s, M_TCPLOG); 1426 if (m != NULL) 1427 m_freem(m); 1428 return (IPPROTO_DONE); 1429 } 1430 1431 /* 1432 * Automatic sizing of receive socket buffer. Often the send 1433 * buffer size is not optimally adjusted to the actual network 1434 * conditions at hand (delay bandwidth product). Setting the 1435 * buffer size too small limits throughput on links with high 1436 * bandwidth and high delay (eg. trans-continental/oceanic links). 1437 * 1438 * On the receive side the socket buffer memory is only rarely 1439 * used to any significant extent. This allows us to be much 1440 * more aggressive in scaling the receive socket buffer. For 1441 * the case that the buffer space is actually used to a large 1442 * extent and we run out of kernel memory we can simply drop 1443 * the new segments; TCP on the sender will just retransmit it 1444 * later. Setting the buffer size too big may only consume too 1445 * much kernel memory if the application doesn't read() from 1446 * the socket or packet loss or reordering makes use of the 1447 * reassembly queue. 1448 * 1449 * The criteria to step up the receive buffer one notch are: 1450 * 1. Application has not set receive buffer size with 1451 * SO_RCVBUF. Setting SO_RCVBUF clears SB_AUTOSIZE. 1452 * 2. the number of bytes received during 1/2 of an sRTT 1453 * is at least 3/8 of the current socket buffer size. 1454 * 3. receive buffer size has not hit maximal automatic size; 1455 * 1456 * If all of the criteria are met we increaset the socket buffer 1457 * by a 1/2 (bounded by the max). This allows us to keep ahead 1458 * of slow-start but also makes it so our peer never gets limited 1459 * by our rwnd which we then open up causing a burst. 1460 * 1461 * This algorithm does two steps per RTT at most and only if 1462 * we receive a bulk stream w/o packet losses or reorderings. 1463 * Shrinking the buffer during idle times is not necessary as 1464 * it doesn't consume any memory when idle. 1465 * 1466 * TODO: Only step up if the application is actually serving 1467 * the buffer to better manage the socket buffer resources. 1468 */ 1469 int 1470 tcp_autorcvbuf(struct mbuf *m, struct tcphdr *th, struct socket *so, 1471 struct tcpcb *tp, int tlen) 1472 { 1473 int newsize = 0; 1474 1475 if (V_tcp_do_autorcvbuf && (so->so_rcv.sb_flags & SB_AUTOSIZE) && 1476 tp->t_srtt != 0 && tp->rfbuf_ts != 0 && 1477 TCP_TS_TO_TICKS(tcp_ts_getticks() - tp->rfbuf_ts) > 1478 ((tp->t_srtt >> TCP_RTT_SHIFT)/2)) { 1479 if (tp->rfbuf_cnt > ((so->so_rcv.sb_hiwat / 2)/ 4 * 3) && 1480 so->so_rcv.sb_hiwat < V_tcp_autorcvbuf_max) { 1481 newsize = min((so->so_rcv.sb_hiwat + (so->so_rcv.sb_hiwat/2)), V_tcp_autorcvbuf_max); 1482 } 1483 TCP_PROBE6(receive__autoresize, NULL, tp, m, tp, th, newsize); 1484 1485 /* Start over with next RTT. */ 1486 tp->rfbuf_ts = 0; 1487 tp->rfbuf_cnt = 0; 1488 } else { 1489 tp->rfbuf_cnt += tlen; /* add up */ 1490 } 1491 return (newsize); 1492 } 1493 1494 int 1495 tcp_input(struct mbuf **mp, int *offp, int proto) 1496 { 1497 return(tcp_input_with_port(mp, offp, proto, 0)); 1498 } 1499 1500 static void 1501 tcp_handle_wakeup(struct tcpcb *tp) 1502 { 1503 1504 INP_WLOCK_ASSERT(tptoinpcb(tp)); 1505 1506 if (tp->t_flags & TF_WAKESOR) { 1507 struct socket *so = tptosocket(tp); 1508 1509 tp->t_flags &= ~TF_WAKESOR; 1510 SOCKBUF_LOCK_ASSERT(&so->so_rcv); 1511 sorwakeup_locked(so); 1512 } 1513 } 1514 1515 void 1516 tcp_do_segment(struct tcpcb *tp, struct mbuf *m, struct tcphdr *th, 1517 int drop_hdrlen, int tlen, uint8_t iptos) 1518 { 1519 uint16_t thflags; 1520 int acked, ourfinisacked, needoutput = 0; 1521 sackstatus_t sack_changed; 1522 int rstreason, todrop, win, incforsyn = 0; 1523 uint32_t tiwin; 1524 uint16_t nsegs; 1525 char *s; 1526 struct inpcb *inp = tptoinpcb(tp); 1527 struct socket *so = tptosocket(tp); 1528 struct in_conninfo *inc = &inp->inp_inc; 1529 struct mbuf *mfree; 1530 struct tcpopt to; 1531 int tfo_syn; 1532 u_int maxseg = 0; 1533 1534 thflags = tcp_get_flags(th); 1535 tp->sackhint.last_sack_ack = 0; 1536 sack_changed = SACK_NOCHANGE; 1537 nsegs = max(1, m->m_pkthdr.lro_nsegs); 1538 1539 NET_EPOCH_ASSERT(); 1540 INP_WLOCK_ASSERT(inp); 1541 KASSERT(tp->t_state > TCPS_LISTEN, ("%s: TCPS_LISTEN", 1542 __func__)); 1543 KASSERT(tp->t_state != TCPS_TIME_WAIT, ("%s: TCPS_TIME_WAIT", 1544 __func__)); 1545 1546 #ifdef TCPPCAP 1547 /* Save segment, if requested. */ 1548 tcp_pcap_add(th, m, &(tp->t_inpkts)); 1549 #endif 1550 TCP_LOG_EVENT(tp, th, &so->so_rcv, &so->so_snd, TCP_LOG_IN, 0, 1551 tlen, NULL, true); 1552 1553 if ((thflags & TH_SYN) && (thflags & TH_FIN) && V_drop_synfin) { 1554 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1555 log(LOG_DEBUG, "%s; %s: " 1556 "SYN|FIN segment ignored (based on " 1557 "sysctl setting)\n", s, __func__); 1558 free(s, M_TCPLOG); 1559 } 1560 goto drop; 1561 } 1562 1563 /* 1564 * If a segment with the ACK-bit set arrives in the SYN-SENT state 1565 * check SEQ.ACK first. 1566 */ 1567 if ((tp->t_state == TCPS_SYN_SENT) && (thflags & TH_ACK) && 1568 (SEQ_LEQ(th->th_ack, tp->iss) || SEQ_GT(th->th_ack, tp->snd_max))) { 1569 rstreason = BANDLIM_UNLIMITED; 1570 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 1571 goto dropwithreset; 1572 } 1573 1574 /* 1575 * Segment received on connection. 1576 * Reset idle time and keep-alive timer. 1577 * XXX: This should be done after segment 1578 * validation to ignore broken/spoofed segs. 1579 */ 1580 if (tp->t_idle_reduce && 1581 (tp->snd_max == tp->snd_una) && 1582 ((ticks - tp->t_rcvtime) >= tp->t_rxtcur)) 1583 cc_after_idle(tp); 1584 tp->t_rcvtime = ticks; 1585 1586 if (thflags & TH_FIN) 1587 tcp_log_end_status(tp, TCP_EI_STATUS_CLIENT_FIN); 1588 /* 1589 * Scale up the window into a 32-bit value. 1590 * For the SYN_SENT state the scale is zero. 1591 */ 1592 tiwin = th->th_win << tp->snd_scale; 1593 #ifdef STATS 1594 stats_voi_update_abs_ulong(tp->t_stats, VOI_TCP_FRWIN, tiwin); 1595 #endif 1596 1597 /* 1598 * TCP ECN processing. 1599 */ 1600 if (tcp_ecn_input_segment(tp, thflags, tlen, 1601 tcp_packets_this_ack(tp, th->th_ack), 1602 iptos)) 1603 cc_cong_signal(tp, th, CC_ECN); 1604 1605 /* 1606 * Parse options on any incoming segment. 1607 */ 1608 tcp_dooptions(&to, (u_char *)(th + 1), 1609 (th->th_off << 2) - sizeof(struct tcphdr), 1610 (thflags & TH_SYN) ? TO_SYN : 0); 1611 1612 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 1613 if ((tp->t_flags & TF_SIGNATURE) != 0 && 1614 (to.to_flags & TOF_SIGNATURE) == 0) { 1615 TCPSTAT_INC(tcps_sig_err_sigopt); 1616 /* XXX: should drop? */ 1617 } 1618 #endif 1619 /* 1620 * If echoed timestamp is later than the current time, 1621 * fall back to non RFC1323 RTT calculation. Normalize 1622 * timestamp if syncookies were used when this connection 1623 * was established. 1624 */ 1625 if ((to.to_flags & TOF_TS) && (to.to_tsecr != 0)) { 1626 to.to_tsecr -= tp->ts_offset; 1627 if (TSTMP_GT(to.to_tsecr, tcp_ts_getticks())) { 1628 to.to_tsecr = 0; 1629 } else if (tp->t_rxtshift == 1 && 1630 tp->t_flags & TF_PREVVALID && 1631 tp->t_badrxtwin != 0 && 1632 TSTMP_LT(to.to_tsecr, tp->t_badrxtwin)) { 1633 cc_cong_signal(tp, th, CC_RTO_ERR); 1634 } 1635 } 1636 /* 1637 * Process options only when we get SYN/ACK back. The SYN case 1638 * for incoming connections is handled in tcp_syncache. 1639 * According to RFC1323 the window field in a SYN (i.e., a <SYN> 1640 * or <SYN,ACK>) segment itself is never scaled. 1641 * XXX this is traditional behavior, may need to be cleaned up. 1642 */ 1643 if (tp->t_state == TCPS_SYN_SENT && (thflags & TH_SYN)) { 1644 /* Handle parallel SYN for ECN */ 1645 tcp_ecn_input_parallel_syn(tp, thflags, iptos); 1646 if ((to.to_flags & TOF_SCALE) && 1647 (tp->t_flags & TF_REQ_SCALE) && 1648 !(tp->t_flags & TF_NOOPT)) { 1649 tp->t_flags |= TF_RCVD_SCALE; 1650 tp->snd_scale = to.to_wscale; 1651 } else { 1652 tp->t_flags &= ~TF_REQ_SCALE; 1653 } 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 } 1668 if (to.to_flags & TOF_MSS) { 1669 tcp_mss(tp, to.to_mss); 1670 } 1671 if ((tp->t_flags & TF_SACK_PERMIT) && 1672 (!(to.to_flags & TOF_SACKPERM) || 1673 (tp->t_flags & TF_NOOPT))) { 1674 tp->t_flags &= ~TF_SACK_PERMIT; 1675 } 1676 if (IS_FASTOPEN(tp->t_flags)) { 1677 if ((to.to_flags & TOF_FASTOPEN) && 1678 !(tp->t_flags & TF_NOOPT)) { 1679 uint16_t mss; 1680 1681 if (to.to_flags & TOF_MSS) { 1682 mss = to.to_mss; 1683 } else { 1684 if ((inp->inp_vflag & INP_IPV6) != 0) { 1685 mss = TCP6_MSS; 1686 } else { 1687 mss = TCP_MSS; 1688 } 1689 } 1690 tcp_fastopen_update_cache(tp, mss, 1691 to.to_tfo_len, to.to_tfo_cookie); 1692 } else { 1693 tcp_fastopen_disable_path(tp); 1694 } 1695 } 1696 } 1697 1698 /* 1699 * If timestamps were negotiated during SYN/ACK and a 1700 * segment without a timestamp is received, silently drop 1701 * the segment, unless it is a RST segment or missing timestamps are 1702 * tolerated. 1703 * See section 3.2 of RFC 7323. 1704 */ 1705 if ((tp->t_flags & TF_RCVD_TSTMP) && !(to.to_flags & TOF_TS)) { 1706 if (((thflags & TH_RST) != 0) || V_tcp_tolerate_missing_ts) { 1707 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1708 log(LOG_DEBUG, "%s; %s: Timestamp missing, " 1709 "segment processed normally\n", 1710 s, __func__); 1711 free(s, M_TCPLOG); 1712 } 1713 } else { 1714 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1715 log(LOG_DEBUG, "%s; %s: Timestamp missing, " 1716 "segment silently dropped\n", s, __func__); 1717 free(s, M_TCPLOG); 1718 } 1719 goto drop; 1720 } 1721 } 1722 /* 1723 * If timestamps were not negotiated during SYN/ACK and a 1724 * segment with a timestamp is received, ignore the 1725 * timestamp and process the packet normally. 1726 * See section 3.2 of RFC 7323. 1727 */ 1728 if (!(tp->t_flags & TF_RCVD_TSTMP) && (to.to_flags & TOF_TS)) { 1729 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1730 log(LOG_DEBUG, "%s; %s: Timestamp not expected, " 1731 "segment processed normally\n", s, __func__); 1732 free(s, M_TCPLOG); 1733 } 1734 } 1735 1736 /* 1737 * Header prediction: check for the two common cases 1738 * of a uni-directional data xfer. If the packet has 1739 * no control flags, is in-sequence, the window didn't 1740 * change and we're not retransmitting, it's a 1741 * candidate. If the length is zero and the ack moved 1742 * forward, we're the sender side of the xfer. Just 1743 * free the data acked & wake any higher level process 1744 * that was blocked waiting for space. If the length 1745 * is non-zero and the ack didn't move, we're the 1746 * receiver side. If we're getting packets in-order 1747 * (the reassembly queue is empty), add the data to 1748 * the socket buffer and note that we need a delayed ack. 1749 * Make sure that the hidden state-flags are also off. 1750 * Since we check for TCPS_ESTABLISHED first, it can only 1751 * be TH_NEEDSYN. 1752 */ 1753 if (tp->t_state == TCPS_ESTABLISHED && 1754 th->th_seq == tp->rcv_nxt && 1755 (thflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK && 1756 tp->snd_nxt == tp->snd_max && 1757 tiwin && tiwin == tp->snd_wnd && 1758 ((tp->t_flags & (TF_NEEDSYN|TF_NEEDFIN)) == 0) && 1759 SEGQ_EMPTY(tp) && 1760 ((to.to_flags & TOF_TS) == 0 || 1761 TSTMP_GEQ(to.to_tsval, tp->ts_recent)) ) { 1762 /* 1763 * If last ACK falls within this segment's sequence numbers, 1764 * record the timestamp. 1765 * NOTE that the test is modified according to the latest 1766 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 1767 */ 1768 if ((to.to_flags & TOF_TS) != 0 && 1769 SEQ_LEQ(th->th_seq, tp->last_ack_sent)) { 1770 tp->ts_recent_age = tcp_ts_getticks(); 1771 tp->ts_recent = to.to_tsval; 1772 } 1773 1774 if (tlen == 0) { 1775 if (SEQ_GT(th->th_ack, tp->snd_una) && 1776 SEQ_LEQ(th->th_ack, tp->snd_max) && 1777 !IN_RECOVERY(tp->t_flags) && 1778 (to.to_flags & TOF_SACK) == 0 && 1779 TAILQ_EMPTY(&tp->snd_holes)) { 1780 /* 1781 * This is a pure ack for outstanding data. 1782 */ 1783 TCPSTAT_INC(tcps_predack); 1784 1785 /* 1786 * "bad retransmit" recovery without timestamps. 1787 */ 1788 if ((to.to_flags & TOF_TS) == 0 && 1789 tp->t_rxtshift == 1 && 1790 tp->t_flags & TF_PREVVALID && 1791 tp->t_badrxtwin != 0 && 1792 TSTMP_LT(ticks, tp->t_badrxtwin)) { 1793 cc_cong_signal(tp, th, CC_RTO_ERR); 1794 } 1795 1796 /* 1797 * Recalculate the transmit timer / rtt. 1798 * 1799 * Some boxes send broken timestamp replies 1800 * during the SYN+ACK phase, ignore 1801 * timestamps of 0 or we could calculate a 1802 * huge RTT and blow up the retransmit timer. 1803 */ 1804 if ((to.to_flags & TOF_TS) != 0 && 1805 to.to_tsecr) { 1806 uint32_t t; 1807 1808 t = tcp_ts_getticks() - to.to_tsecr; 1809 if (!tp->t_rttlow || tp->t_rttlow > t) 1810 tp->t_rttlow = t; 1811 tcp_xmit_timer(tp, 1812 TCP_TS_TO_TICKS(t) + 1); 1813 } else if (tp->t_rtttime && 1814 SEQ_GT(th->th_ack, tp->t_rtseq)) { 1815 if (!tp->t_rttlow || 1816 tp->t_rttlow > ticks - tp->t_rtttime) 1817 tp->t_rttlow = ticks - tp->t_rtttime; 1818 tcp_xmit_timer(tp, 1819 ticks - tp->t_rtttime); 1820 } 1821 acked = BYTES_THIS_ACK(tp, th); 1822 1823 #ifdef TCP_HHOOK 1824 /* Run HHOOK_TCP_ESTABLISHED_IN helper hooks. */ 1825 hhook_run_tcp_est_in(tp, th, &to); 1826 #endif 1827 1828 TCPSTAT_ADD(tcps_rcvackpack, nsegs); 1829 TCPSTAT_ADD(tcps_rcvackbyte, acked); 1830 sbdrop(&so->so_snd, acked); 1831 if (SEQ_GT(tp->snd_una, tp->snd_recover) && 1832 SEQ_LEQ(th->th_ack, tp->snd_recover)) 1833 tp->snd_recover = th->th_ack - 1; 1834 1835 /* 1836 * Let the congestion control algorithm update 1837 * congestion control related information. This 1838 * typically means increasing the congestion 1839 * window. 1840 */ 1841 cc_ack_received(tp, th, nsegs, CC_ACK); 1842 1843 tp->snd_una = th->th_ack; 1844 /* 1845 * Pull snd_wl2 up to prevent seq wrap relative 1846 * to th_ack. 1847 */ 1848 tp->snd_wl2 = th->th_ack; 1849 tp->t_dupacks = 0; 1850 m_freem(m); 1851 1852 /* 1853 * If all outstanding data are acked, stop 1854 * retransmit timer, otherwise restart timer 1855 * using current (possibly backed-off) value. 1856 * If process is waiting for space, 1857 * wakeup/selwakeup/signal. If data 1858 * are ready to send, let tcp_output 1859 * decide between more output or persist. 1860 */ 1861 TCP_PROBE3(debug__input, tp, th, m); 1862 /* 1863 * Clear t_acktime if remote side has ACKd 1864 * all data in the socket buffer. 1865 * Otherwise, update t_acktime if we received 1866 * a sufficiently large ACK. 1867 */ 1868 if (sbavail(&so->so_snd) == 0) 1869 tp->t_acktime = 0; 1870 else if (acked > 1) 1871 tp->t_acktime = ticks; 1872 if (tp->snd_una == tp->snd_max) 1873 tcp_timer_activate(tp, TT_REXMT, 0); 1874 else if (!tcp_timer_active(tp, TT_PERSIST)) 1875 tcp_timer_activate(tp, TT_REXMT, 1876 TP_RXTCUR(tp)); 1877 sowwakeup(so); 1878 /* 1879 * Only call tcp_output when there 1880 * is new data available to be sent 1881 * or we need to send an ACK. 1882 */ 1883 if ((tp->t_flags & TF_ACKNOW) || 1884 (sbavail(&so->so_snd) >= 1885 SEQ_SUB(tp->snd_max, tp->snd_una))) { 1886 (void) tcp_output(tp); 1887 } 1888 goto check_delack; 1889 } 1890 } else if (th->th_ack == tp->snd_una && 1891 tlen <= sbspace(&so->so_rcv)) { 1892 int newsize = 0; /* automatic sockbuf scaling */ 1893 1894 /* 1895 * This is a pure, in-sequence data packet with 1896 * nothing on the reassembly queue and we have enough 1897 * buffer space to take it. 1898 */ 1899 /* Clean receiver SACK report if present */ 1900 if ((tp->t_flags & TF_SACK_PERMIT) && tp->rcv_numsacks) 1901 tcp_clean_sackreport(tp); 1902 TCPSTAT_INC(tcps_preddat); 1903 tp->rcv_nxt += tlen; 1904 if (tlen && 1905 ((tp->t_flags2 & TF2_FBYTES_COMPLETE) == 0) && 1906 (tp->t_fbyte_in == 0)) { 1907 tp->t_fbyte_in = ticks; 1908 if (tp->t_fbyte_in == 0) 1909 tp->t_fbyte_in = 1; 1910 if (tp->t_fbyte_out && tp->t_fbyte_in) 1911 tp->t_flags2 |= TF2_FBYTES_COMPLETE; 1912 } 1913 /* 1914 * Pull snd_wl1 up to prevent seq wrap relative to 1915 * th_seq. 1916 */ 1917 tp->snd_wl1 = th->th_seq; 1918 /* 1919 * Pull rcv_up up to prevent seq wrap relative to 1920 * rcv_nxt. 1921 */ 1922 tp->rcv_up = tp->rcv_nxt; 1923 TCPSTAT_ADD(tcps_rcvpack, nsegs); 1924 TCPSTAT_ADD(tcps_rcvbyte, tlen); 1925 TCP_PROBE3(debug__input, tp, th, m); 1926 1927 newsize = tcp_autorcvbuf(m, th, so, tp, tlen); 1928 1929 /* Add data to socket buffer. */ 1930 SOCKBUF_LOCK(&so->so_rcv); 1931 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 1932 m_freem(m); 1933 } else { 1934 /* 1935 * Set new socket buffer size. 1936 * Give up when limit is reached. 1937 */ 1938 if (newsize) 1939 if (!sbreserve_locked(so, SO_RCV, 1940 newsize, NULL)) 1941 so->so_rcv.sb_flags &= ~SB_AUTOSIZE; 1942 m_adj(m, drop_hdrlen); /* delayed header drop */ 1943 sbappendstream_locked(&so->so_rcv, m, 0); 1944 } 1945 /* NB: sorwakeup_locked() does an implicit unlock. */ 1946 sorwakeup_locked(so); 1947 if (DELAY_ACK(tp, tlen)) { 1948 tp->t_flags |= TF_DELACK; 1949 } else { 1950 tp->t_flags |= TF_ACKNOW; 1951 tcp_output(tp); 1952 } 1953 goto check_delack; 1954 } 1955 } 1956 1957 /* 1958 * Calculate amount of space in receive window, 1959 * and then do TCP input processing. 1960 * Receive window is amount of space in rcv queue, 1961 * but not less than advertised window. 1962 */ 1963 win = sbspace(&so->so_rcv); 1964 if (win < 0) 1965 win = 0; 1966 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 1967 1968 switch (tp->t_state) { 1969 /* 1970 * If the state is SYN_RECEIVED: 1971 * if seg contains an ACK, but not for our SYN/ACK, send a RST. 1972 */ 1973 case TCPS_SYN_RECEIVED: 1974 if (thflags & TH_RST) { 1975 /* Handle RST segments later. */ 1976 break; 1977 } 1978 if ((thflags & TH_ACK) && 1979 (SEQ_LEQ(th->th_ack, tp->snd_una) || 1980 SEQ_GT(th->th_ack, tp->snd_max))) { 1981 rstreason = BANDLIM_RST_OPENPORT; 1982 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 1983 goto dropwithreset; 1984 } 1985 if (IS_FASTOPEN(tp->t_flags)) { 1986 /* 1987 * When a TFO connection is in SYN_RECEIVED, the 1988 * only valid packets are the initial SYN, a 1989 * retransmit/copy of the initial SYN (possibly with 1990 * a subset of the original data), a valid ACK, a 1991 * FIN, or a RST. 1992 */ 1993 if ((thflags & (TH_SYN|TH_ACK)) == (TH_SYN|TH_ACK)) { 1994 rstreason = BANDLIM_RST_OPENPORT; 1995 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 1996 goto dropwithreset; 1997 } else if (thflags & TH_SYN) { 1998 /* non-initial SYN is ignored */ 1999 if ((tcp_timer_active(tp, TT_DELACK) || 2000 tcp_timer_active(tp, TT_REXMT))) 2001 goto drop; 2002 } else if (!(thflags & (TH_ACK|TH_FIN|TH_RST))) { 2003 goto drop; 2004 } 2005 } 2006 break; 2007 2008 /* 2009 * If the state is SYN_SENT: 2010 * if seg contains a RST with valid ACK (SEQ.ACK has already 2011 * been verified), then drop the connection. 2012 * if seg contains a RST without an ACK, drop the seg. 2013 * if seg does not contain SYN, then drop the seg. 2014 * Otherwise this is an acceptable SYN segment 2015 * initialize tp->rcv_nxt and tp->irs 2016 * if seg contains ack then advance tp->snd_una 2017 * if seg contains an ECE and ECN support is enabled, the stream 2018 * is ECN capable. 2019 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 2020 * arrange for segment to be acked (eventually) 2021 * continue processing rest of data/controls, beginning with URG 2022 */ 2023 case TCPS_SYN_SENT: 2024 if ((thflags & (TH_ACK|TH_RST)) == (TH_ACK|TH_RST)) { 2025 TCP_PROBE5(connect__refused, NULL, tp, 2026 m, tp, th); 2027 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 2028 tp = tcp_drop(tp, ECONNREFUSED); 2029 } 2030 if (thflags & TH_RST) 2031 goto drop; 2032 if (!(thflags & TH_SYN)) 2033 goto drop; 2034 2035 tp->irs = th->th_seq; 2036 tcp_rcvseqinit(tp); 2037 if (thflags & TH_ACK) { 2038 int tfo_partial_ack = 0; 2039 2040 TCPSTAT_INC(tcps_connects); 2041 soisconnected(so); 2042 #ifdef MAC 2043 mac_socketpeer_set_from_mbuf(m, so); 2044 #endif 2045 /* Do window scaling on this connection? */ 2046 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2047 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2048 tp->rcv_scale = tp->request_r_scale; 2049 } 2050 tp->rcv_adv += min(tp->rcv_wnd, 2051 TCP_MAXWIN << tp->rcv_scale); 2052 tp->snd_una++; /* SYN is acked */ 2053 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2054 tp->snd_nxt = tp->snd_una; 2055 /* 2056 * If not all the data that was sent in the TFO SYN 2057 * has been acked, resend the remainder right away. 2058 */ 2059 if (IS_FASTOPEN(tp->t_flags) && 2060 (tp->snd_una != tp->snd_max)) { 2061 tp->snd_nxt = th->th_ack; 2062 tfo_partial_ack = 1; 2063 } 2064 /* 2065 * If there's data, delay ACK; if there's also a FIN 2066 * ACKNOW will be turned on later. 2067 */ 2068 if (DELAY_ACK(tp, tlen) && tlen != 0 && !tfo_partial_ack) 2069 tcp_timer_activate(tp, TT_DELACK, 2070 tcp_delacktime); 2071 else 2072 tp->t_flags |= TF_ACKNOW; 2073 2074 tcp_ecn_input_syn_sent(tp, thflags, iptos); 2075 2076 /* 2077 * Received <SYN,ACK> in SYN_SENT[*] state. 2078 * Transitions: 2079 * SYN_SENT --> ESTABLISHED 2080 * SYN_SENT* --> FIN_WAIT_1 2081 */ 2082 tp->t_starttime = ticks; 2083 if (tp->t_flags & TF_NEEDFIN) { 2084 tp->t_acktime = ticks; 2085 tcp_state_change(tp, TCPS_FIN_WAIT_1); 2086 tp->t_flags &= ~TF_NEEDFIN; 2087 thflags &= ~TH_SYN; 2088 } else { 2089 tcp_state_change(tp, TCPS_ESTABLISHED); 2090 TCP_PROBE5(connect__established, NULL, tp, 2091 m, tp, th); 2092 cc_conn_init(tp); 2093 tcp_timer_activate(tp, TT_KEEP, 2094 TP_KEEPIDLE(tp)); 2095 } 2096 } else { 2097 /* 2098 * Received initial SYN in SYN-SENT[*] state => 2099 * simultaneous open. 2100 * If it succeeds, connection is * half-synchronized. 2101 * Otherwise, do 3-way handshake: 2102 * SYN-SENT -> SYN-RECEIVED 2103 * SYN-SENT* -> SYN-RECEIVED* 2104 */ 2105 tp->t_flags |= (TF_ACKNOW | TF_NEEDSYN | TF_SONOTCONN); 2106 tcp_timer_activate(tp, TT_REXMT, 0); 2107 tcp_state_change(tp, TCPS_SYN_RECEIVED); 2108 } 2109 2110 /* 2111 * Advance th->th_seq to correspond to first data byte. 2112 * If data, trim to stay within window, 2113 * dropping FIN if necessary. 2114 */ 2115 th->th_seq++; 2116 if (tlen > tp->rcv_wnd) { 2117 todrop = tlen - tp->rcv_wnd; 2118 m_adj(m, -todrop); 2119 tlen = tp->rcv_wnd; 2120 thflags &= ~TH_FIN; 2121 TCPSTAT_INC(tcps_rcvpackafterwin); 2122 TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); 2123 } 2124 tp->snd_wl1 = th->th_seq - 1; 2125 tp->rcv_up = th->th_seq; 2126 /* 2127 * Client side of transaction: already sent SYN and data. 2128 * If the remote host used T/TCP to validate the SYN, 2129 * our data will be ACK'd; if so, enter normal data segment 2130 * processing in the middle of step 5, ack processing. 2131 * Otherwise, goto step 6. 2132 */ 2133 if (thflags & TH_ACK) 2134 goto process_ACK; 2135 2136 goto step6; 2137 } 2138 2139 /* 2140 * States other than LISTEN or SYN_SENT. 2141 * First check the RST flag and sequence number since reset segments 2142 * are exempt from the timestamp and connection count tests. This 2143 * fixes a bug introduced by the Stevens, vol. 2, p. 960 bugfix 2144 * below which allowed reset segments in half the sequence space 2145 * to fall though and be processed (which gives forged reset 2146 * segments with a random sequence number a 50 percent chance of 2147 * killing a connection). 2148 * Then check timestamp, if present. 2149 * Then check the connection count, if present. 2150 * Then check that at least some bytes of segment are within 2151 * receive window. If segment begins before rcv_nxt, 2152 * drop leading data (and SYN); if nothing left, just ack. 2153 */ 2154 if (thflags & TH_RST) { 2155 /* 2156 * RFC5961 Section 3.2 2157 * 2158 * - RST drops connection only if SEG.SEQ == RCV.NXT. 2159 * - If RST is in window, we send challenge ACK. 2160 * 2161 * Note: to take into account delayed ACKs, we should 2162 * test against last_ack_sent instead of rcv_nxt. 2163 * Note 2: we handle special case of closed window, not 2164 * covered by the RFC. 2165 */ 2166 if ((SEQ_GEQ(th->th_seq, tp->last_ack_sent) && 2167 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) || 2168 (tp->rcv_wnd == 0 && tp->last_ack_sent == th->th_seq)) { 2169 KASSERT(tp->t_state != TCPS_SYN_SENT, 2170 ("%s: TH_RST for TCPS_SYN_SENT th %p tp %p", 2171 __func__, th, tp)); 2172 2173 if (V_tcp_insecure_rst || 2174 tp->last_ack_sent == th->th_seq) { 2175 TCPSTAT_INC(tcps_drops); 2176 /* Drop the connection. */ 2177 switch (tp->t_state) { 2178 case TCPS_SYN_RECEIVED: 2179 so->so_error = ECONNREFUSED; 2180 goto close; 2181 case TCPS_ESTABLISHED: 2182 case TCPS_FIN_WAIT_1: 2183 case TCPS_FIN_WAIT_2: 2184 case TCPS_CLOSE_WAIT: 2185 case TCPS_CLOSING: 2186 case TCPS_LAST_ACK: 2187 so->so_error = ECONNRESET; 2188 close: 2189 /* FALLTHROUGH */ 2190 default: 2191 tcp_log_end_status(tp, TCP_EI_STATUS_CLIENT_RST); 2192 tp = tcp_close(tp); 2193 } 2194 } else { 2195 TCPSTAT_INC(tcps_badrst); 2196 /* Send challenge ACK. */ 2197 tcp_respond(tp, mtod(m, void *), th, m, 2198 tp->rcv_nxt, tp->snd_nxt, TH_ACK); 2199 tp->last_ack_sent = tp->rcv_nxt; 2200 m = NULL; 2201 } 2202 } 2203 goto drop; 2204 } 2205 2206 /* 2207 * RFC5961 Section 4.2 2208 * Send challenge ACK for any SYN in synchronized state. 2209 */ 2210 if ((thflags & TH_SYN) && tp->t_state != TCPS_SYN_SENT && 2211 tp->t_state != TCPS_SYN_RECEIVED) { 2212 TCPSTAT_INC(tcps_badsyn); 2213 if (V_tcp_insecure_syn && 2214 SEQ_GEQ(th->th_seq, tp->last_ack_sent) && 2215 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) { 2216 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 2217 tp = tcp_drop(tp, ECONNRESET); 2218 rstreason = BANDLIM_UNLIMITED; 2219 } else { 2220 tcp_ecn_input_syn_sent(tp, thflags, iptos); 2221 /* Send challenge ACK. */ 2222 tcp_respond(tp, mtod(m, void *), th, m, tp->rcv_nxt, 2223 tp->snd_nxt, TH_ACK); 2224 tp->last_ack_sent = tp->rcv_nxt; 2225 m = NULL; 2226 } 2227 goto drop; 2228 } 2229 2230 /* 2231 * RFC 1323 PAWS: If we have a timestamp reply on this segment 2232 * and it's less than ts_recent, drop it. 2233 */ 2234 if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent && 2235 TSTMP_LT(to.to_tsval, tp->ts_recent)) { 2236 /* Check to see if ts_recent is over 24 days old. */ 2237 if (tcp_ts_getticks() - tp->ts_recent_age > TCP_PAWS_IDLE) { 2238 /* 2239 * Invalidate ts_recent. If this segment updates 2240 * ts_recent, the age will be reset later and ts_recent 2241 * will get a valid value. If it does not, setting 2242 * ts_recent to zero will at least satisfy the 2243 * requirement that zero be placed in the timestamp 2244 * echo reply when ts_recent isn't valid. The 2245 * age isn't reset until we get a valid ts_recent 2246 * because we don't want out-of-order segments to be 2247 * dropped when ts_recent is old. 2248 */ 2249 tp->ts_recent = 0; 2250 } else { 2251 TCPSTAT_INC(tcps_rcvduppack); 2252 TCPSTAT_ADD(tcps_rcvdupbyte, tlen); 2253 TCPSTAT_INC(tcps_pawsdrop); 2254 if (tlen) 2255 goto dropafterack; 2256 goto drop; 2257 } 2258 } 2259 2260 /* 2261 * In the SYN-RECEIVED state, validate that the packet belongs to 2262 * this connection before trimming the data to fit the receive 2263 * window. Check the sequence number versus IRS since we know 2264 * the sequence numbers haven't wrapped. This is a partial fix 2265 * for the "LAND" DoS attack. 2266 */ 2267 if (tp->t_state == TCPS_SYN_RECEIVED && SEQ_LT(th->th_seq, tp->irs)) { 2268 rstreason = BANDLIM_RST_OPENPORT; 2269 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 2270 goto dropwithreset; 2271 } 2272 2273 todrop = tp->rcv_nxt - th->th_seq; 2274 if (todrop > 0) { 2275 if (thflags & TH_SYN) { 2276 thflags &= ~TH_SYN; 2277 th->th_seq++; 2278 if (th->th_urp > 1) 2279 th->th_urp--; 2280 else 2281 thflags &= ~TH_URG; 2282 todrop--; 2283 } 2284 /* 2285 * Following if statement from Stevens, vol. 2, p. 960. 2286 */ 2287 if (todrop > tlen 2288 || (todrop == tlen && (thflags & TH_FIN) == 0)) { 2289 /* 2290 * Any valid FIN must be to the left of the window. 2291 * At this point the FIN must be a duplicate or out 2292 * of sequence; drop it. 2293 */ 2294 thflags &= ~TH_FIN; 2295 2296 /* 2297 * Send an ACK to resynchronize and drop any data. 2298 * But keep on processing for RST or ACK. 2299 */ 2300 tp->t_flags |= TF_ACKNOW; 2301 todrop = tlen; 2302 TCPSTAT_INC(tcps_rcvduppack); 2303 TCPSTAT_ADD(tcps_rcvdupbyte, todrop); 2304 } else { 2305 TCPSTAT_INC(tcps_rcvpartduppack); 2306 TCPSTAT_ADD(tcps_rcvpartdupbyte, todrop); 2307 } 2308 /* 2309 * DSACK - add SACK block for dropped range 2310 */ 2311 if ((todrop > 0) && (tp->t_flags & TF_SACK_PERMIT)) { 2312 tcp_update_sack_list(tp, th->th_seq, 2313 th->th_seq + todrop); 2314 /* 2315 * ACK now, as the next in-sequence segment 2316 * will clear the DSACK block again 2317 */ 2318 tp->t_flags |= TF_ACKNOW; 2319 } 2320 drop_hdrlen += todrop; /* drop from the top afterwards */ 2321 th->th_seq += todrop; 2322 tlen -= todrop; 2323 if (th->th_urp > todrop) 2324 th->th_urp -= todrop; 2325 else { 2326 thflags &= ~TH_URG; 2327 th->th_urp = 0; 2328 } 2329 } 2330 2331 /* 2332 * If new data are received on a connection after the 2333 * user processes are gone, then RST the other end. 2334 */ 2335 if ((tp->t_flags & TF_CLOSED) && tlen) { 2336 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 2337 log(LOG_DEBUG, "%s; %s: %s: Received %d bytes of data " 2338 "after socket was closed, " 2339 "sending RST and removing tcpcb\n", 2340 s, __func__, tcpstates[tp->t_state], tlen); 2341 free(s, M_TCPLOG); 2342 } 2343 tcp_log_end_status(tp, TCP_EI_STATUS_DATA_A_CLOSE); 2344 /* tcp_close will kill the inp pre-log the Reset */ 2345 tcp_log_end_status(tp, TCP_EI_STATUS_SERVER_RST); 2346 tp = tcp_close(tp); 2347 TCPSTAT_INC(tcps_rcvafterclose); 2348 rstreason = BANDLIM_UNLIMITED; 2349 goto dropwithreset; 2350 } 2351 2352 /* 2353 * If segment ends after window, drop trailing data 2354 * (and PUSH and FIN); if nothing left, just ACK. 2355 */ 2356 todrop = (th->th_seq + tlen) - (tp->rcv_nxt + tp->rcv_wnd); 2357 if (todrop > 0) { 2358 TCPSTAT_INC(tcps_rcvpackafterwin); 2359 if (todrop >= tlen) { 2360 TCPSTAT_ADD(tcps_rcvbyteafterwin, tlen); 2361 /* 2362 * If window is closed can only take segments at 2363 * window edge, and have to drop data and PUSH from 2364 * incoming segments. Continue processing, but 2365 * remember to ack. Otherwise, drop segment 2366 * and ack. 2367 */ 2368 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 2369 tp->t_flags |= TF_ACKNOW; 2370 TCPSTAT_INC(tcps_rcvwinprobe); 2371 } else 2372 goto dropafterack; 2373 } else 2374 TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); 2375 m_adj(m, -todrop); 2376 tlen -= todrop; 2377 thflags &= ~(TH_PUSH|TH_FIN); 2378 } 2379 2380 /* 2381 * If last ACK falls within this segment's sequence numbers, 2382 * record its timestamp. 2383 * NOTE: 2384 * 1) That the test incorporates suggestions from the latest 2385 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 2386 * 2) That updating only on newer timestamps interferes with 2387 * our earlier PAWS tests, so this check should be solely 2388 * predicated on the sequence space of this segment. 2389 * 3) That we modify the segment boundary check to be 2390 * Last.ACK.Sent <= SEG.SEQ + SEG.Len 2391 * instead of RFC1323's 2392 * Last.ACK.Sent < SEG.SEQ + SEG.Len, 2393 * This modified check allows us to overcome RFC1323's 2394 * limitations as described in Stevens TCP/IP Illustrated 2395 * Vol. 2 p.869. In such cases, we can still calculate the 2396 * RTT correctly when RCV.NXT == Last.ACK.Sent. 2397 */ 2398 if ((to.to_flags & TOF_TS) != 0 && 2399 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 2400 SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen + 2401 ((thflags & (TH_SYN|TH_FIN)) != 0))) { 2402 tp->ts_recent_age = tcp_ts_getticks(); 2403 tp->ts_recent = to.to_tsval; 2404 } 2405 2406 /* 2407 * If the ACK bit is off: if in SYN-RECEIVED state or SENDSYN 2408 * flag is on (half-synchronized state), then queue data for 2409 * later processing; else drop segment and return. 2410 */ 2411 if ((thflags & TH_ACK) == 0) { 2412 if (tp->t_state == TCPS_SYN_RECEIVED || 2413 (tp->t_flags & TF_NEEDSYN)) { 2414 if (tp->t_state == TCPS_SYN_RECEIVED && 2415 IS_FASTOPEN(tp->t_flags)) { 2416 tp->snd_wnd = tiwin; 2417 cc_conn_init(tp); 2418 } 2419 goto step6; 2420 } else if (tp->t_flags & TF_ACKNOW) 2421 goto dropafterack; 2422 else 2423 goto drop; 2424 } 2425 2426 /* 2427 * Ack processing. 2428 */ 2429 switch (tp->t_state) { 2430 /* 2431 * In SYN_RECEIVED state, the ack ACKs our SYN, so enter 2432 * ESTABLISHED state and continue processing. 2433 * The ACK was checked above. 2434 */ 2435 case TCPS_SYN_RECEIVED: 2436 2437 TCPSTAT_INC(tcps_connects); 2438 if (tp->t_flags & TF_SONOTCONN) { 2439 /* 2440 * Usually SYN_RECEIVED had been created from a LISTEN, 2441 * and solisten_enqueue() has already marked the socket 2442 * layer as connected. If it didn't, which can happen 2443 * only with an accept_filter(9), then the tp is marked 2444 * with TF_SONOTCONN. The other reason for this mark 2445 * to be set is a simultaneous open, a SYN_RECEIVED 2446 * that had been created from SYN_SENT. 2447 */ 2448 tp->t_flags &= ~TF_SONOTCONN; 2449 soisconnected(so); 2450 } 2451 /* Do window scaling? */ 2452 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2453 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2454 tp->rcv_scale = tp->request_r_scale; 2455 } 2456 tp->snd_wnd = tiwin; 2457 /* 2458 * Make transitions: 2459 * SYN-RECEIVED -> ESTABLISHED 2460 * SYN-RECEIVED* -> FIN-WAIT-1 2461 */ 2462 tp->t_starttime = ticks; 2463 if (IS_FASTOPEN(tp->t_flags) && tp->t_tfo_pending) { 2464 tcp_fastopen_decrement_counter(tp->t_tfo_pending); 2465 tp->t_tfo_pending = NULL; 2466 } 2467 if (tp->t_flags & TF_NEEDFIN) { 2468 tp->t_acktime = ticks; 2469 tcp_state_change(tp, TCPS_FIN_WAIT_1); 2470 tp->t_flags &= ~TF_NEEDFIN; 2471 } else { 2472 tcp_state_change(tp, TCPS_ESTABLISHED); 2473 TCP_PROBE5(accept__established, NULL, tp, 2474 m, tp, th); 2475 /* 2476 * TFO connections call cc_conn_init() during SYN 2477 * processing. Calling it again here for such 2478 * connections is not harmless as it would undo the 2479 * snd_cwnd reduction that occurs when a TFO SYN|ACK 2480 * is retransmitted. 2481 */ 2482 if (!IS_FASTOPEN(tp->t_flags)) 2483 cc_conn_init(tp); 2484 tcp_timer_activate(tp, TT_KEEP, TP_KEEPIDLE(tp)); 2485 } 2486 /* 2487 * Account for the ACK of our SYN prior to 2488 * regular ACK processing below, except for 2489 * simultaneous SYN, which is handled later. 2490 */ 2491 if (SEQ_GT(th->th_ack, tp->snd_una) && !(tp->t_flags & TF_NEEDSYN)) 2492 incforsyn = 1; 2493 /* 2494 * If segment contains data or ACK, will call tcp_reass() 2495 * later; if not, do so now to pass queued data to user. 2496 */ 2497 if (tlen == 0 && (thflags & TH_FIN) == 0) { 2498 (void) tcp_reass(tp, (struct tcphdr *)0, NULL, 0, 2499 (struct mbuf *)0); 2500 tcp_handle_wakeup(tp); 2501 } 2502 tp->snd_wl1 = th->th_seq - 1; 2503 /* FALLTHROUGH */ 2504 2505 /* 2506 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 2507 * ACKs. If the ack is in the range 2508 * tp->snd_una < th->th_ack <= tp->snd_max 2509 * then advance tp->snd_una to th->th_ack and drop 2510 * data from the retransmission queue. If this ACK reflects 2511 * more up to date window information we update our window information. 2512 */ 2513 case TCPS_ESTABLISHED: 2514 case TCPS_FIN_WAIT_1: 2515 case TCPS_FIN_WAIT_2: 2516 case TCPS_CLOSE_WAIT: 2517 case TCPS_CLOSING: 2518 case TCPS_LAST_ACK: 2519 if (SEQ_GT(th->th_ack, tp->snd_max)) { 2520 TCPSTAT_INC(tcps_rcvacktoomuch); 2521 goto dropafterack; 2522 } 2523 if (tcp_is_sack_recovery(tp, &to)) { 2524 sack_changed = tcp_sack_doack(tp, &to, th->th_ack); 2525 if ((sack_changed != SACK_NOCHANGE) && 2526 (tp->t_flags & TF_LRD)) { 2527 tcp_sack_lost_retransmission(tp, th); 2528 } 2529 } else 2530 /* 2531 * Reset the value so that previous (valid) value 2532 * from the last ack with SACK doesn't get used. 2533 */ 2534 tp->sackhint.sacked_bytes = 0; 2535 2536 #ifdef TCP_HHOOK 2537 /* Run HHOOK_TCP_ESTABLISHED_IN helper hooks. */ 2538 hhook_run_tcp_est_in(tp, th, &to); 2539 #endif 2540 2541 if (SEQ_LEQ(th->th_ack, tp->snd_una)) { 2542 maxseg = tcp_maxseg(tp); 2543 if (tlen == 0 && 2544 (tiwin == tp->snd_wnd || 2545 (tp->t_flags & TF_SACK_PERMIT))) { 2546 /* 2547 * If this is the first time we've seen a 2548 * FIN from the remote, this is not a 2549 * duplicate and it needs to be processed 2550 * normally. This happens during a 2551 * simultaneous close. 2552 */ 2553 if ((thflags & TH_FIN) && 2554 (TCPS_HAVERCVDFIN(tp->t_state) == 0)) { 2555 tp->t_dupacks = 0; 2556 break; 2557 } 2558 TCPSTAT_INC(tcps_rcvdupack); 2559 /* 2560 * If we have outstanding data (other than 2561 * a window probe), this is a completely 2562 * duplicate ack (ie, window info didn't 2563 * change and FIN isn't set), 2564 * the ack is the biggest we've 2565 * seen and we've seen exactly our rexmt 2566 * threshold of them, assume a packet 2567 * has been dropped and retransmit it. 2568 * Kludge snd_nxt & the congestion 2569 * window so we send only this one 2570 * packet. 2571 * 2572 * We know we're losing at the current 2573 * window size so do congestion avoidance 2574 * (set ssthresh to half the current window 2575 * and pull our congestion window back to 2576 * the new ssthresh). 2577 * 2578 * Dup acks mean that packets have left the 2579 * network (they're now cached at the receiver) 2580 * so bump cwnd by the amount in the receiver 2581 * to keep a constant cwnd packets in the 2582 * network. 2583 * 2584 * When using TCP ECN, notify the peer that 2585 * we reduced the cwnd. 2586 */ 2587 /* 2588 * Following 2 kinds of acks should not affect 2589 * dupack counting: 2590 * 1) Old acks 2591 * 2) Acks with SACK but without any new SACK 2592 * information in them. These could result from 2593 * any anomaly in the network like a switch 2594 * duplicating packets or a possible DoS attack. 2595 */ 2596 if (th->th_ack != tp->snd_una || 2597 (tcp_is_sack_recovery(tp, &to) && 2598 (sack_changed == SACK_NOCHANGE))) { 2599 break; 2600 } else if (!tcp_timer_active(tp, TT_REXMT)) { 2601 tp->t_dupacks = 0; 2602 } else if (++tp->t_dupacks > tcprexmtthresh || 2603 IN_FASTRECOVERY(tp->t_flags)) { 2604 cc_ack_received(tp, th, nsegs, 2605 CC_DUPACK); 2606 if (V_tcp_do_prr && 2607 IN_FASTRECOVERY(tp->t_flags) && 2608 (tp->t_flags & TF_SACK_PERMIT)) { 2609 tcp_do_prr_ack(tp, th, &to, 2610 sack_changed, &maxseg); 2611 } else if (tcp_is_sack_recovery(tp, &to) && 2612 IN_FASTRECOVERY(tp->t_flags)) { 2613 int awnd; 2614 2615 /* 2616 * Compute the amount of data in flight first. 2617 * We can inject new data into the pipe iff 2618 * we have less than 1/2 the original window's 2619 * worth of data in flight. 2620 */ 2621 if (V_tcp_do_newsack) { 2622 awnd = tcp_compute_pipe(tp); 2623 } else { 2624 awnd = (tp->snd_nxt - tp->snd_fack) + 2625 tp->sackhint.sack_bytes_rexmit; 2626 } 2627 if (awnd < tp->snd_ssthresh) { 2628 tp->snd_cwnd += maxseg; 2629 if (tp->snd_cwnd > tp->snd_ssthresh) 2630 tp->snd_cwnd = tp->snd_ssthresh; 2631 } 2632 } else { 2633 tp->snd_cwnd += maxseg; 2634 } 2635 (void) tcp_output(tp); 2636 goto drop; 2637 } else if (tp->t_dupacks == tcprexmtthresh || 2638 (tp->t_flags & TF_SACK_PERMIT && 2639 V_tcp_do_newsack && 2640 tp->sackhint.sacked_bytes > 2641 (tcprexmtthresh - 1) * maxseg)) { 2642 enter_recovery: 2643 /* 2644 * Above is the RFC6675 trigger condition of 2645 * more than (dupthresh-1)*maxseg sacked data. 2646 * If the count of holes in the 2647 * scoreboard is >= dupthresh, we could 2648 * also enter loss recovery, but don't 2649 * have that value readily available. 2650 */ 2651 tp->t_dupacks = tcprexmtthresh; 2652 tcp_seq onxt = tp->snd_nxt; 2653 2654 /* 2655 * If we're doing sack, or prr, check 2656 * to see if we're already in sack 2657 * recovery. If we're not doing sack, 2658 * check to see if we're in newreno 2659 * recovery. 2660 */ 2661 if (V_tcp_do_prr || 2662 (tp->t_flags & TF_SACK_PERMIT)) { 2663 if (IN_FASTRECOVERY(tp->t_flags)) { 2664 tp->t_dupacks = 0; 2665 break; 2666 } 2667 } else { 2668 if (SEQ_LEQ(th->th_ack, 2669 tp->snd_recover)) { 2670 tp->t_dupacks = 0; 2671 break; 2672 } 2673 } 2674 /* Congestion signal before ack. */ 2675 cc_cong_signal(tp, th, CC_NDUPACK); 2676 cc_ack_received(tp, th, nsegs, 2677 CC_DUPACK); 2678 tcp_timer_activate(tp, TT_REXMT, 0); 2679 tp->t_rtttime = 0; 2680 if (V_tcp_do_prr) { 2681 /* 2682 * snd_ssthresh is already updated by 2683 * cc_cong_signal. 2684 */ 2685 if (tcp_is_sack_recovery(tp, &to)) { 2686 /* 2687 * Exclude Limited Transmit 2688 * segments here 2689 */ 2690 tp->sackhint.prr_delivered = 2691 maxseg; 2692 } else { 2693 tp->sackhint.prr_delivered = 2694 imin(tp->snd_max - tp->snd_una, 2695 imin(INT_MAX / 65536, 2696 tp->t_dupacks) * maxseg); 2697 } 2698 tp->sackhint.recover_fs = max(1, 2699 tp->snd_nxt - tp->snd_una); 2700 } 2701 if (tcp_is_sack_recovery(tp, &to)) { 2702 TCPSTAT_INC(tcps_sack_recovery_episode); 2703 tp->snd_recover = tp->snd_nxt; 2704 tp->snd_cwnd = maxseg; 2705 (void) tcp_output(tp); 2706 if (SEQ_GT(th->th_ack, tp->snd_una)) { 2707 goto resume_partialack; 2708 } 2709 goto drop; 2710 } 2711 tp->snd_nxt = th->th_ack; 2712 tp->snd_cwnd = maxseg; 2713 (void) tcp_output(tp); 2714 KASSERT(tp->snd_limited <= 2, 2715 ("%s: tp->snd_limited too big", 2716 __func__)); 2717 tp->snd_cwnd = tp->snd_ssthresh + 2718 maxseg * 2719 (tp->t_dupacks - tp->snd_limited); 2720 if (SEQ_GT(onxt, tp->snd_nxt)) 2721 tp->snd_nxt = onxt; 2722 goto drop; 2723 } else if (V_tcp_do_rfc3042) { 2724 /* 2725 * Process first and second duplicate 2726 * ACKs. Each indicates a segment 2727 * leaving the network, creating room 2728 * for more. Make sure we can send a 2729 * packet on reception of each duplicate 2730 * ACK by increasing snd_cwnd by one 2731 * segment. Restore the original 2732 * snd_cwnd after packet transmission. 2733 */ 2734 cc_ack_received(tp, th, nsegs, CC_DUPACK); 2735 uint32_t oldcwnd = tp->snd_cwnd; 2736 tcp_seq oldsndmax = tp->snd_max; 2737 u_int sent; 2738 int avail; 2739 2740 KASSERT(tp->t_dupacks == 1 || 2741 tp->t_dupacks == 2, 2742 ("%s: dupacks not 1 or 2", 2743 __func__)); 2744 if (tp->t_dupacks == 1) 2745 tp->snd_limited = 0; 2746 tp->snd_cwnd = 2747 (tp->snd_nxt - tp->snd_una) + 2748 (tp->t_dupacks - tp->snd_limited) * 2749 maxseg; 2750 /* 2751 * Only call tcp_output when there 2752 * is new data available to be sent 2753 * or we need to send an ACK. 2754 */ 2755 SOCKBUF_LOCK(&so->so_snd); 2756 avail = sbavail(&so->so_snd); 2757 SOCKBUF_UNLOCK(&so->so_snd); 2758 if (tp->t_flags & TF_ACKNOW || 2759 (avail >= 2760 SEQ_SUB(tp->snd_nxt, tp->snd_una))) { 2761 (void) tcp_output(tp); 2762 } 2763 sent = SEQ_SUB(tp->snd_max, oldsndmax); 2764 if (sent > maxseg) { 2765 KASSERT((tp->t_dupacks == 2 && 2766 tp->snd_limited == 0) || 2767 (sent == maxseg + 1 && 2768 tp->t_flags & TF_SENTFIN), 2769 ("%s: sent too much", 2770 __func__)); 2771 tp->snd_limited = 2; 2772 } else if (sent > 0) { 2773 ++tp->snd_limited; 2774 } 2775 tp->snd_cwnd = oldcwnd; 2776 goto drop; 2777 } 2778 } 2779 break; 2780 } else { 2781 /* 2782 * This ack is advancing the left edge, reset the 2783 * counter. 2784 */ 2785 tp->t_dupacks = 0; 2786 /* 2787 * If this ack also has new SACK info, increment the 2788 * counter as per rfc6675. The variable 2789 * sack_changed tracks all changes to the SACK 2790 * scoreboard, including when partial ACKs without 2791 * SACK options are received, and clear the scoreboard 2792 * from the left side. Such partial ACKs should not be 2793 * counted as dupacks here. 2794 */ 2795 if (tcp_is_sack_recovery(tp, &to) && 2796 (sack_changed != SACK_NOCHANGE)) { 2797 tp->t_dupacks++; 2798 /* limit overhead by setting maxseg last */ 2799 if (!IN_FASTRECOVERY(tp->t_flags) && 2800 (tp->sackhint.sacked_bytes > 2801 ((tcprexmtthresh - 1) * 2802 (maxseg = tcp_maxseg(tp))))) { 2803 goto enter_recovery; 2804 } 2805 } 2806 } 2807 2808 resume_partialack: 2809 KASSERT(SEQ_GT(th->th_ack, tp->snd_una), 2810 ("%s: th_ack <= snd_una", __func__)); 2811 2812 /* 2813 * If the congestion window was inflated to account 2814 * for the other side's cached packets, retract it. 2815 */ 2816 if (IN_FASTRECOVERY(tp->t_flags)) { 2817 if (SEQ_LT(th->th_ack, tp->snd_recover)) { 2818 if (tp->t_flags & TF_SACK_PERMIT) { 2819 if (V_tcp_do_prr && to.to_flags & TOF_SACK) { 2820 tcp_timer_activate(tp, TT_REXMT, 0); 2821 tp->t_rtttime = 0; 2822 tcp_do_prr_ack(tp, th, &to, 2823 sack_changed, &maxseg); 2824 tp->t_flags |= TF_ACKNOW; 2825 (void) tcp_output(tp); 2826 } else { 2827 tcp_sack_partialack(tp, th, 2828 &maxseg); 2829 } 2830 } else { 2831 tcp_newreno_partial_ack(tp, th); 2832 } 2833 } else { 2834 cc_post_recovery(tp, th); 2835 } 2836 } else if (IN_CONGRECOVERY(tp->t_flags)) { 2837 if (SEQ_LT(th->th_ack, tp->snd_recover)) { 2838 if (V_tcp_do_prr) { 2839 tp->sackhint.delivered_data = BYTES_THIS_ACK(tp, th); 2840 tp->snd_fack = th->th_ack; 2841 /* 2842 * During ECN cwnd reduction 2843 * always use PRR-SSRB 2844 */ 2845 tcp_do_prr_ack(tp, th, &to, SACK_CHANGE, 2846 &maxseg); 2847 (void) tcp_output(tp); 2848 } 2849 } else { 2850 cc_post_recovery(tp, th); 2851 } 2852 } 2853 /* 2854 * If we reach this point, ACK is not a duplicate, 2855 * i.e., it ACKs something we sent. 2856 */ 2857 if (tp->t_flags & TF_NEEDSYN) { 2858 /* 2859 * T/TCP: Connection was half-synchronized, and our 2860 * SYN has been ACK'd (so connection is now fully 2861 * synchronized). Go to non-starred state, 2862 * increment snd_una for ACK of SYN, and check if 2863 * we can do window scaling. 2864 */ 2865 tp->t_flags &= ~TF_NEEDSYN; 2866 tp->snd_una++; 2867 /* Do window scaling? */ 2868 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2869 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2870 tp->rcv_scale = tp->request_r_scale; 2871 /* Send window already scaled. */ 2872 } 2873 } 2874 2875 process_ACK: 2876 INP_WLOCK_ASSERT(inp); 2877 2878 /* 2879 * Adjust for the SYN bit in sequence space, 2880 * but don't account for it in cwnd calculations. 2881 * This is for the SYN_RECEIVED, non-simultaneous 2882 * SYN case. SYN_SENT and simultaneous SYN are 2883 * treated elsewhere. 2884 */ 2885 if (incforsyn) 2886 tp->snd_una++; 2887 acked = BYTES_THIS_ACK(tp, th); 2888 KASSERT(acked >= 0, ("%s: acked unexepectedly negative " 2889 "(tp->snd_una=%u, th->th_ack=%u, tp=%p, m=%p)", __func__, 2890 tp->snd_una, th->th_ack, tp, m)); 2891 TCPSTAT_ADD(tcps_rcvackpack, nsegs); 2892 TCPSTAT_ADD(tcps_rcvackbyte, acked); 2893 2894 /* 2895 * If we just performed our first retransmit, and the ACK 2896 * arrives within our recovery window, then it was a mistake 2897 * to do the retransmit in the first place. Recover our 2898 * original cwnd and ssthresh, and proceed to transmit where 2899 * we left off. 2900 */ 2901 if (tp->t_rxtshift == 1 && 2902 tp->t_flags & TF_PREVVALID && 2903 tp->t_badrxtwin != 0 && 2904 to.to_flags & TOF_TS && 2905 to.to_tsecr != 0 && 2906 TSTMP_LT(to.to_tsecr, tp->t_badrxtwin)) 2907 cc_cong_signal(tp, th, CC_RTO_ERR); 2908 2909 /* 2910 * If we have a timestamp reply, update smoothed 2911 * round trip time. If no timestamp is present but 2912 * transmit timer is running and timed sequence 2913 * number was acked, update smoothed round trip time. 2914 * Since we now have an rtt measurement, cancel the 2915 * timer backoff (cf., Phil Karn's retransmit alg.). 2916 * Recompute the initial retransmit timer. 2917 * 2918 * Some boxes send broken timestamp replies 2919 * during the SYN+ACK phase, ignore 2920 * timestamps of 0 or we could calculate a 2921 * huge RTT and blow up the retransmit timer. 2922 */ 2923 if ((to.to_flags & TOF_TS) != 0 && to.to_tsecr) { 2924 uint32_t t; 2925 2926 t = tcp_ts_getticks() - to.to_tsecr; 2927 if (!tp->t_rttlow || tp->t_rttlow > t) 2928 tp->t_rttlow = t; 2929 tcp_xmit_timer(tp, TCP_TS_TO_TICKS(t) + 1); 2930 } else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) { 2931 if (!tp->t_rttlow || tp->t_rttlow > ticks - tp->t_rtttime) 2932 tp->t_rttlow = ticks - tp->t_rtttime; 2933 tcp_xmit_timer(tp, ticks - tp->t_rtttime); 2934 } 2935 2936 SOCKBUF_LOCK(&so->so_snd); 2937 /* 2938 * Clear t_acktime if remote side has ACKd all data in the 2939 * socket buffer and FIN (if applicable). 2940 * Otherwise, update t_acktime if we received a sufficiently 2941 * large ACK. 2942 */ 2943 if ((tp->t_state <= TCPS_CLOSE_WAIT && 2944 acked == sbavail(&so->so_snd)) || 2945 acked > sbavail(&so->so_snd)) 2946 tp->t_acktime = 0; 2947 else if (acked > 1) 2948 tp->t_acktime = ticks; 2949 2950 /* 2951 * If all outstanding data is acked, stop retransmit 2952 * timer and remember to restart (more output or persist). 2953 * If there is more data to be acked, restart retransmit 2954 * timer, using current (possibly backed-off) value. 2955 */ 2956 if (th->th_ack == tp->snd_max) { 2957 tcp_timer_activate(tp, TT_REXMT, 0); 2958 needoutput = 1; 2959 } else if (!tcp_timer_active(tp, TT_PERSIST)) 2960 tcp_timer_activate(tp, TT_REXMT, TP_RXTCUR(tp)); 2961 2962 /* 2963 * If no data (only SYN) was ACK'd, 2964 * skip rest of ACK processing. 2965 */ 2966 if (acked == 0) { 2967 SOCKBUF_UNLOCK(&so->so_snd); 2968 goto step6; 2969 } 2970 2971 /* 2972 * Let the congestion control algorithm update congestion 2973 * control related information. This typically means increasing 2974 * the congestion window. 2975 */ 2976 cc_ack_received(tp, th, nsegs, CC_ACK); 2977 2978 if (acked > sbavail(&so->so_snd)) { 2979 if (tp->snd_wnd >= sbavail(&so->so_snd)) 2980 tp->snd_wnd -= sbavail(&so->so_snd); 2981 else 2982 tp->snd_wnd = 0; 2983 mfree = sbcut_locked(&so->so_snd, 2984 (int)sbavail(&so->so_snd)); 2985 ourfinisacked = 1; 2986 } else { 2987 mfree = sbcut_locked(&so->so_snd, acked); 2988 if (tp->snd_wnd >= (uint32_t) acked) 2989 tp->snd_wnd -= acked; 2990 else 2991 tp->snd_wnd = 0; 2992 ourfinisacked = 0; 2993 } 2994 /* NB: sowwakeup_locked() does an implicit unlock. */ 2995 sowwakeup_locked(so); 2996 m_freem(mfree); 2997 /* Detect una wraparound. */ 2998 if (!IN_RECOVERY(tp->t_flags) && 2999 SEQ_GT(tp->snd_una, tp->snd_recover) && 3000 SEQ_LEQ(th->th_ack, tp->snd_recover)) 3001 tp->snd_recover = th->th_ack - 1; 3002 /* XXXLAS: Can this be moved up into cc_post_recovery? */ 3003 if (IN_RECOVERY(tp->t_flags) && 3004 SEQ_GEQ(th->th_ack, tp->snd_recover)) { 3005 EXIT_RECOVERY(tp->t_flags); 3006 } 3007 tp->snd_una = th->th_ack; 3008 if (tp->t_flags & TF_SACK_PERMIT) { 3009 if (SEQ_GT(tp->snd_una, tp->snd_recover)) 3010 tp->snd_recover = tp->snd_una; 3011 } 3012 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 3013 tp->snd_nxt = tp->snd_una; 3014 3015 switch (tp->t_state) { 3016 /* 3017 * In FIN_WAIT_1 STATE in addition to the processing 3018 * for the ESTABLISHED state if our FIN is now acknowledged 3019 * then enter FIN_WAIT_2. 3020 */ 3021 case TCPS_FIN_WAIT_1: 3022 if (ourfinisacked) { 3023 /* 3024 * If we can't receive any more 3025 * data, then closing user can proceed. 3026 * Starting the timer is contrary to the 3027 * specification, but if we don't get a FIN 3028 * we'll hang forever. 3029 */ 3030 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 3031 soisdisconnected(so); 3032 tcp_timer_activate(tp, TT_2MSL, 3033 (tcp_fast_finwait2_recycle ? 3034 tcp_finwait2_timeout : 3035 TP_MAXIDLE(tp))); 3036 } 3037 tcp_state_change(tp, TCPS_FIN_WAIT_2); 3038 } 3039 break; 3040 3041 /* 3042 * In CLOSING STATE in addition to the processing for 3043 * the ESTABLISHED state if the ACK acknowledges our FIN 3044 * then enter the TIME-WAIT state, otherwise ignore 3045 * the segment. 3046 */ 3047 case TCPS_CLOSING: 3048 if (ourfinisacked) { 3049 tcp_twstart(tp); 3050 m_freem(m); 3051 return; 3052 } 3053 break; 3054 3055 /* 3056 * In LAST_ACK, we may still be waiting for data to drain 3057 * and/or to be acked, as well as for the ack of our FIN. 3058 * If our FIN is now acknowledged, delete the TCB, 3059 * enter the closed state and return. 3060 */ 3061 case TCPS_LAST_ACK: 3062 if (ourfinisacked) { 3063 tp = tcp_close(tp); 3064 goto drop; 3065 } 3066 break; 3067 } 3068 } 3069 3070 step6: 3071 INP_WLOCK_ASSERT(inp); 3072 3073 /* 3074 * Update window information. 3075 * Don't look at window if no ACK: TAC's send garbage on first SYN. 3076 */ 3077 if ((thflags & TH_ACK) && 3078 (SEQ_LT(tp->snd_wl1, th->th_seq) || 3079 (tp->snd_wl1 == th->th_seq && (SEQ_LT(tp->snd_wl2, th->th_ack) || 3080 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))) { 3081 /* keep track of pure window updates */ 3082 if (tlen == 0 && 3083 tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) 3084 TCPSTAT_INC(tcps_rcvwinupd); 3085 tp->snd_wnd = tiwin; 3086 tp->snd_wl1 = th->th_seq; 3087 tp->snd_wl2 = th->th_ack; 3088 if (tp->snd_wnd > tp->max_sndwnd) 3089 tp->max_sndwnd = tp->snd_wnd; 3090 needoutput = 1; 3091 } 3092 3093 /* 3094 * Process segments with URG. 3095 */ 3096 if ((thflags & TH_URG) && th->th_urp && 3097 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3098 /* 3099 * This is a kludge, but if we receive and accept 3100 * random urgent pointers, we'll crash in 3101 * soreceive. It's hard to imagine someone 3102 * actually wanting to send this much urgent data. 3103 */ 3104 SOCKBUF_LOCK(&so->so_rcv); 3105 if (th->th_urp + sbavail(&so->so_rcv) > sb_max) { 3106 th->th_urp = 0; /* XXX */ 3107 thflags &= ~TH_URG; /* XXX */ 3108 SOCKBUF_UNLOCK(&so->so_rcv); /* XXX */ 3109 goto dodata; /* XXX */ 3110 } 3111 /* 3112 * If this segment advances the known urgent pointer, 3113 * then mark the data stream. This should not happen 3114 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 3115 * a FIN has been received from the remote side. 3116 * In these states we ignore the URG. 3117 * 3118 * According to RFC961 (Assigned Protocols), 3119 * the urgent pointer points to the last octet 3120 * of urgent data. We continue, however, 3121 * to consider it to indicate the first octet 3122 * of data past the urgent section as the original 3123 * spec states (in one of two places). 3124 */ 3125 if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) { 3126 tp->rcv_up = th->th_seq + th->th_urp; 3127 so->so_oobmark = sbavail(&so->so_rcv) + 3128 (tp->rcv_up - tp->rcv_nxt) - 1; 3129 if (so->so_oobmark == 0) 3130 so->so_rcv.sb_state |= SBS_RCVATMARK; 3131 sohasoutofband(so); 3132 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); 3133 } 3134 SOCKBUF_UNLOCK(&so->so_rcv); 3135 /* 3136 * Remove out of band data so doesn't get presented to user. 3137 * This can happen independent of advancing the URG pointer, 3138 * but if two URG's are pending at once, some out-of-band 3139 * data may creep in... ick. 3140 */ 3141 if (th->th_urp <= (uint32_t)tlen && 3142 !(so->so_options & SO_OOBINLINE)) { 3143 /* hdr drop is delayed */ 3144 tcp_pulloutofband(so, th, m, drop_hdrlen); 3145 } 3146 } else { 3147 /* 3148 * If no out of band data is expected, 3149 * pull receive urgent pointer along 3150 * with the receive window. 3151 */ 3152 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) 3153 tp->rcv_up = tp->rcv_nxt; 3154 } 3155 dodata: /* XXX */ 3156 INP_WLOCK_ASSERT(inp); 3157 3158 /* 3159 * Process the segment text, merging it into the TCP sequencing queue, 3160 * and arranging for acknowledgment of receipt if necessary. 3161 * This process logically involves adjusting tp->rcv_wnd as data 3162 * is presented to the user (this happens in tcp_usrreq.c, 3163 * case PRU_RCVD). If a FIN has already been received on this 3164 * connection then we just ignore the text. 3165 */ 3166 tfo_syn = ((tp->t_state == TCPS_SYN_RECEIVED) && 3167 IS_FASTOPEN(tp->t_flags)); 3168 if ((tlen || (thflags & TH_FIN) || (tfo_syn && tlen > 0)) && 3169 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3170 tcp_seq save_start = th->th_seq; 3171 tcp_seq save_rnxt = tp->rcv_nxt; 3172 int save_tlen = tlen; 3173 m_adj(m, drop_hdrlen); /* delayed header drop */ 3174 /* 3175 * Insert segment which includes th into TCP reassembly queue 3176 * with control block tp. Set thflags to whether reassembly now 3177 * includes a segment with FIN. This handles the common case 3178 * inline (segment is the next to be received on an established 3179 * connection, and the queue is empty), avoiding linkage into 3180 * and removal from the queue and repetition of various 3181 * conversions. 3182 * Set DELACK for segments received in order, but ack 3183 * immediately when segments are out of order (so 3184 * fast retransmit can work). 3185 */ 3186 if (th->th_seq == tp->rcv_nxt && 3187 SEGQ_EMPTY(tp) && 3188 (TCPS_HAVEESTABLISHED(tp->t_state) || 3189 tfo_syn)) { 3190 if (DELAY_ACK(tp, tlen) || tfo_syn) 3191 tp->t_flags |= TF_DELACK; 3192 else 3193 tp->t_flags |= TF_ACKNOW; 3194 tp->rcv_nxt += tlen; 3195 if (tlen && 3196 ((tp->t_flags2 & TF2_FBYTES_COMPLETE) == 0) && 3197 (tp->t_fbyte_in == 0)) { 3198 tp->t_fbyte_in = ticks; 3199 if (tp->t_fbyte_in == 0) 3200 tp->t_fbyte_in = 1; 3201 if (tp->t_fbyte_out && tp->t_fbyte_in) 3202 tp->t_flags2 |= TF2_FBYTES_COMPLETE; 3203 } 3204 thflags = tcp_get_flags(th) & TH_FIN; 3205 TCPSTAT_INC(tcps_rcvpack); 3206 TCPSTAT_ADD(tcps_rcvbyte, tlen); 3207 SOCKBUF_LOCK(&so->so_rcv); 3208 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) 3209 m_freem(m); 3210 else 3211 sbappendstream_locked(&so->so_rcv, m, 0); 3212 tp->t_flags |= TF_WAKESOR; 3213 } else { 3214 /* 3215 * XXX: Due to the header drop above "th" is 3216 * theoretically invalid by now. Fortunately 3217 * m_adj() doesn't actually frees any mbufs 3218 * when trimming from the head. 3219 */ 3220 tcp_seq temp = save_start; 3221 3222 thflags = tcp_reass(tp, th, &temp, &tlen, m); 3223 tp->t_flags |= TF_ACKNOW; 3224 } 3225 if ((tp->t_flags & TF_SACK_PERMIT) && 3226 (save_tlen > 0) && 3227 TCPS_HAVEESTABLISHED(tp->t_state)) { 3228 if ((tlen == 0) && (SEQ_LT(save_start, save_rnxt))) { 3229 /* 3230 * DSACK actually handled in the fastpath 3231 * above. 3232 */ 3233 tcp_update_sack_list(tp, save_start, 3234 save_start + save_tlen); 3235 } else if ((tlen > 0) && SEQ_GT(tp->rcv_nxt, save_rnxt)) { 3236 if ((tp->rcv_numsacks >= 1) && 3237 (tp->sackblks[0].end == save_start)) { 3238 /* 3239 * Partial overlap, recorded at todrop 3240 * above. 3241 */ 3242 tcp_update_sack_list(tp, 3243 tp->sackblks[0].start, 3244 tp->sackblks[0].end); 3245 } else { 3246 tcp_update_dsack_list(tp, save_start, 3247 save_start + save_tlen); 3248 } 3249 } else if (tlen >= save_tlen) { 3250 /* Update of sackblks. */ 3251 tcp_update_dsack_list(tp, save_start, 3252 save_start + save_tlen); 3253 } else if (tlen > 0) { 3254 tcp_update_dsack_list(tp, save_start, 3255 save_start + tlen); 3256 } 3257 } 3258 tcp_handle_wakeup(tp); 3259 #if 0 3260 /* 3261 * Note the amount of data that peer has sent into 3262 * our window, in order to estimate the sender's 3263 * buffer size. 3264 * XXX: Unused. 3265 */ 3266 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt)) 3267 len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); 3268 else 3269 len = so->so_rcv.sb_hiwat; 3270 #endif 3271 } else { 3272 m_freem(m); 3273 thflags &= ~TH_FIN; 3274 } 3275 3276 /* 3277 * If FIN is received ACK the FIN and let the user know 3278 * that the connection is closing. 3279 */ 3280 if (thflags & TH_FIN) { 3281 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3282 /* The socket upcall is handled by socantrcvmore. */ 3283 socantrcvmore(so); 3284 /* 3285 * If connection is half-synchronized 3286 * (ie NEEDSYN flag on) then delay ACK, 3287 * so it may be piggybacked when SYN is sent. 3288 * Otherwise, since we received a FIN then no 3289 * more input can be expected, send ACK now. 3290 */ 3291 if (tp->t_flags & TF_NEEDSYN) 3292 tp->t_flags |= TF_DELACK; 3293 else 3294 tp->t_flags |= TF_ACKNOW; 3295 tp->rcv_nxt++; 3296 } 3297 switch (tp->t_state) { 3298 /* 3299 * In SYN_RECEIVED and ESTABLISHED STATES 3300 * enter the CLOSE_WAIT state. 3301 */ 3302 case TCPS_SYN_RECEIVED: 3303 tp->t_starttime = ticks; 3304 /* FALLTHROUGH */ 3305 case TCPS_ESTABLISHED: 3306 tcp_state_change(tp, TCPS_CLOSE_WAIT); 3307 break; 3308 3309 /* 3310 * If still in FIN_WAIT_1 STATE FIN has not been acked so 3311 * enter the CLOSING state. 3312 */ 3313 case TCPS_FIN_WAIT_1: 3314 tcp_state_change(tp, TCPS_CLOSING); 3315 break; 3316 3317 /* 3318 * In FIN_WAIT_2 state enter the TIME_WAIT state, 3319 * starting the time-wait timer, turning off the other 3320 * standard timers. 3321 */ 3322 case TCPS_FIN_WAIT_2: 3323 tcp_twstart(tp); 3324 return; 3325 } 3326 } 3327 TCP_PROBE3(debug__input, tp, th, m); 3328 3329 /* 3330 * Return any desired output. 3331 */ 3332 if (needoutput || (tp->t_flags & TF_ACKNOW)) { 3333 (void) tcp_output(tp); 3334 } 3335 check_delack: 3336 INP_WLOCK_ASSERT(inp); 3337 3338 if (tp->t_flags & TF_DELACK) { 3339 tp->t_flags &= ~TF_DELACK; 3340 tcp_timer_activate(tp, TT_DELACK, tcp_delacktime); 3341 } 3342 INP_WUNLOCK(inp); 3343 return; 3344 3345 dropafterack: 3346 /* 3347 * Generate an ACK dropping incoming segment if it occupies 3348 * sequence space, where the ACK reflects our state. 3349 * 3350 * We can now skip the test for the RST flag since all 3351 * paths to this code happen after packets containing 3352 * RST have been dropped. 3353 * 3354 * In the SYN-RECEIVED state, don't send an ACK unless the 3355 * segment we received passes the SYN-RECEIVED ACK test. 3356 * If it fails send a RST. This breaks the loop in the 3357 * "LAND" DoS attack, and also prevents an ACK storm 3358 * between two listening ports that have been sent forged 3359 * SYN segments, each with the source address of the other. 3360 */ 3361 if (tp->t_state == TCPS_SYN_RECEIVED && (thflags & TH_ACK) && 3362 (SEQ_GT(tp->snd_una, th->th_ack) || 3363 SEQ_GT(th->th_ack, tp->snd_max)) ) { 3364 rstreason = BANDLIM_RST_OPENPORT; 3365 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 3366 goto dropwithreset; 3367 } 3368 TCP_PROBE3(debug__input, tp, th, m); 3369 tp->t_flags |= TF_ACKNOW; 3370 (void) tcp_output(tp); 3371 INP_WUNLOCK(inp); 3372 m_freem(m); 3373 return; 3374 3375 dropwithreset: 3376 if (tp != NULL) { 3377 tcp_dropwithreset(m, th, tp, tlen, rstreason); 3378 INP_WUNLOCK(inp); 3379 } else 3380 tcp_dropwithreset(m, th, NULL, tlen, rstreason); 3381 return; 3382 3383 drop: 3384 /* 3385 * Drop space held by incoming segment and return. 3386 */ 3387 TCP_PROBE3(debug__input, tp, th, m); 3388 if (tp != NULL) { 3389 INP_WUNLOCK(inp); 3390 } 3391 m_freem(m); 3392 } 3393 3394 /* 3395 * Issue RST and make ACK acceptable to originator of segment. 3396 * The mbuf must still include the original packet header. 3397 * tp may be NULL. 3398 */ 3399 void 3400 tcp_dropwithreset(struct mbuf *m, struct tcphdr *th, struct tcpcb *tp, 3401 int tlen, int rstreason) 3402 { 3403 #ifdef INET 3404 struct ip *ip; 3405 #endif 3406 #ifdef INET6 3407 struct ip6_hdr *ip6; 3408 #endif 3409 3410 if (tp != NULL) { 3411 INP_LOCK_ASSERT(tptoinpcb(tp)); 3412 } 3413 3414 /* Don't bother if destination was broadcast/multicast. */ 3415 if ((tcp_get_flags(th) & TH_RST) || m->m_flags & (M_BCAST|M_MCAST)) 3416 goto drop; 3417 #ifdef INET6 3418 if (mtod(m, struct ip *)->ip_v == 6) { 3419 ip6 = mtod(m, struct ip6_hdr *); 3420 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 3421 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) 3422 goto drop; 3423 /* IPv6 anycast check is done at tcp6_input() */ 3424 } 3425 #endif 3426 #if defined(INET) && defined(INET6) 3427 else 3428 #endif 3429 #ifdef INET 3430 { 3431 ip = mtod(m, struct ip *); 3432 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || 3433 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 3434 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || 3435 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 3436 goto drop; 3437 } 3438 #endif 3439 3440 /* Perform bandwidth limiting. */ 3441 if (badport_bandlim(rstreason) < 0) 3442 goto drop; 3443 3444 /* tcp_respond consumes the mbuf chain. */ 3445 if (tcp_get_flags(th) & TH_ACK) { 3446 tcp_respond(tp, mtod(m, void *), th, m, (tcp_seq)0, 3447 th->th_ack, TH_RST); 3448 } else { 3449 if (tcp_get_flags(th) & TH_SYN) 3450 tlen++; 3451 if (tcp_get_flags(th) & TH_FIN) 3452 tlen++; 3453 tcp_respond(tp, mtod(m, void *), th, m, th->th_seq+tlen, 3454 (tcp_seq)0, TH_RST|TH_ACK); 3455 } 3456 return; 3457 drop: 3458 m_freem(m); 3459 } 3460 3461 /* 3462 * Parse TCP options and place in tcpopt. 3463 */ 3464 void 3465 tcp_dooptions(struct tcpopt *to, u_char *cp, int cnt, int flags) 3466 { 3467 int opt, optlen; 3468 3469 to->to_flags = 0; 3470 for (; cnt > 0; cnt -= optlen, cp += optlen) { 3471 opt = cp[0]; 3472 if (opt == TCPOPT_EOL) 3473 break; 3474 if (opt == TCPOPT_NOP) 3475 optlen = 1; 3476 else { 3477 if (cnt < 2) 3478 break; 3479 optlen = cp[1]; 3480 if (optlen < 2 || optlen > cnt) 3481 break; 3482 } 3483 switch (opt) { 3484 case TCPOPT_MAXSEG: 3485 if (optlen != TCPOLEN_MAXSEG) 3486 continue; 3487 if (!(flags & TO_SYN)) 3488 continue; 3489 to->to_flags |= TOF_MSS; 3490 bcopy((char *)cp + 2, 3491 (char *)&to->to_mss, sizeof(to->to_mss)); 3492 to->to_mss = ntohs(to->to_mss); 3493 break; 3494 case TCPOPT_WINDOW: 3495 if (optlen != TCPOLEN_WINDOW) 3496 continue; 3497 if (!(flags & TO_SYN)) 3498 continue; 3499 to->to_flags |= TOF_SCALE; 3500 to->to_wscale = min(cp[2], TCP_MAX_WINSHIFT); 3501 break; 3502 case TCPOPT_TIMESTAMP: 3503 if (optlen != TCPOLEN_TIMESTAMP) 3504 continue; 3505 to->to_flags |= TOF_TS; 3506 bcopy((char *)cp + 2, 3507 (char *)&to->to_tsval, sizeof(to->to_tsval)); 3508 to->to_tsval = ntohl(to->to_tsval); 3509 bcopy((char *)cp + 6, 3510 (char *)&to->to_tsecr, sizeof(to->to_tsecr)); 3511 to->to_tsecr = ntohl(to->to_tsecr); 3512 break; 3513 case TCPOPT_SIGNATURE: 3514 /* 3515 * In order to reply to a host which has set the 3516 * TCP_SIGNATURE option in its initial SYN, we have 3517 * to record the fact that the option was observed 3518 * here for the syncache code to perform the correct 3519 * response. 3520 */ 3521 if (optlen != TCPOLEN_SIGNATURE) 3522 continue; 3523 to->to_flags |= TOF_SIGNATURE; 3524 to->to_signature = cp + 2; 3525 break; 3526 case TCPOPT_SACK_PERMITTED: 3527 if (optlen != TCPOLEN_SACK_PERMITTED) 3528 continue; 3529 if (!(flags & TO_SYN)) 3530 continue; 3531 if (!V_tcp_do_sack) 3532 continue; 3533 to->to_flags |= TOF_SACKPERM; 3534 break; 3535 case TCPOPT_SACK: 3536 if (optlen <= 2 || (optlen - 2) % TCPOLEN_SACK != 0) 3537 continue; 3538 if (flags & TO_SYN) 3539 continue; 3540 to->to_flags |= TOF_SACK; 3541 to->to_nsacks = (optlen - 2) / TCPOLEN_SACK; 3542 to->to_sacks = cp + 2; 3543 TCPSTAT_INC(tcps_sack_rcv_blocks); 3544 break; 3545 case TCPOPT_FAST_OPEN: 3546 /* 3547 * Cookie length validation is performed by the 3548 * server side cookie checking code or the client 3549 * side cookie cache update code. 3550 */ 3551 if (!(flags & TO_SYN)) 3552 continue; 3553 if (!V_tcp_fastopen_client_enable && 3554 !V_tcp_fastopen_server_enable) 3555 continue; 3556 to->to_flags |= TOF_FASTOPEN; 3557 to->to_tfo_len = optlen - 2; 3558 to->to_tfo_cookie = to->to_tfo_len ? cp + 2 : NULL; 3559 break; 3560 default: 3561 continue; 3562 } 3563 } 3564 } 3565 3566 /* 3567 * Pull out of band byte out of a segment so 3568 * it doesn't appear in the user's data queue. 3569 * It is still reflected in the segment length for 3570 * sequencing purposes. 3571 */ 3572 void 3573 tcp_pulloutofband(struct socket *so, struct tcphdr *th, struct mbuf *m, 3574 int off) 3575 { 3576 int cnt = off + th->th_urp - 1; 3577 3578 while (cnt >= 0) { 3579 if (m->m_len > cnt) { 3580 char *cp = mtod(m, caddr_t) + cnt; 3581 struct tcpcb *tp = sototcpcb(so); 3582 3583 INP_WLOCK_ASSERT(tptoinpcb(tp)); 3584 3585 tp->t_iobc = *cp; 3586 tp->t_oobflags |= TCPOOB_HAVEDATA; 3587 bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); 3588 m->m_len--; 3589 if (m->m_flags & M_PKTHDR) 3590 m->m_pkthdr.len--; 3591 return; 3592 } 3593 cnt -= m->m_len; 3594 m = m->m_next; 3595 if (m == NULL) 3596 break; 3597 } 3598 panic("tcp_pulloutofband"); 3599 } 3600 3601 /* 3602 * Collect new round-trip time estimate 3603 * and update averages and current timeout. 3604 */ 3605 void 3606 tcp_xmit_timer(struct tcpcb *tp, int rtt) 3607 { 3608 int delta; 3609 3610 INP_WLOCK_ASSERT(tptoinpcb(tp)); 3611 3612 TCPSTAT_INC(tcps_rttupdated); 3613 if (tp->t_rttupdated < UCHAR_MAX) 3614 tp->t_rttupdated++; 3615 #ifdef STATS 3616 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_RTT, 3617 imax(0, rtt * 1000 / hz)); 3618 #endif 3619 if ((tp->t_srtt != 0) && (tp->t_rxtshift <= TCP_RTT_INVALIDATE)) { 3620 /* 3621 * srtt is stored as fixed point with 5 bits after the 3622 * binary point (i.e., scaled by 8). The following magic 3623 * is equivalent to the smoothing algorithm in rfc793 with 3624 * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed 3625 * point). Adjust rtt to origin 0. 3626 */ 3627 delta = ((rtt - 1) << TCP_DELTA_SHIFT) 3628 - (tp->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT)); 3629 3630 if ((tp->t_srtt += delta) <= 0) 3631 tp->t_srtt = 1; 3632 3633 /* 3634 * We accumulate a smoothed rtt variance (actually, a 3635 * smoothed mean difference), then set the retransmit 3636 * timer to smoothed rtt + 4 times the smoothed variance. 3637 * rttvar is stored as fixed point with 4 bits after the 3638 * binary point (scaled by 16). The following is 3639 * equivalent to rfc793 smoothing with an alpha of .75 3640 * (rttvar = rttvar*3/4 + |delta| / 4). This replaces 3641 * rfc793's wired-in beta. 3642 */ 3643 if (delta < 0) 3644 delta = -delta; 3645 delta -= tp->t_rttvar >> (TCP_RTTVAR_SHIFT - TCP_DELTA_SHIFT); 3646 if ((tp->t_rttvar += delta) <= 0) 3647 tp->t_rttvar = 1; 3648 } else { 3649 /* 3650 * No rtt measurement yet - use the unsmoothed rtt. 3651 * Set the variance to half the rtt (so our first 3652 * retransmit happens at 3*rtt). 3653 */ 3654 tp->t_srtt = rtt << TCP_RTT_SHIFT; 3655 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1); 3656 } 3657 tp->t_rtttime = 0; 3658 tp->t_rxtshift = 0; 3659 3660 /* 3661 * the retransmit should happen at rtt + 4 * rttvar. 3662 * Because of the way we do the smoothing, srtt and rttvar 3663 * will each average +1/2 tick of bias. When we compute 3664 * the retransmit timer, we want 1/2 tick of rounding and 3665 * 1 extra tick because of +-1/2 tick uncertainty in the 3666 * firing of the timer. The bias will give us exactly the 3667 * 1.5 tick we need. But, because the bias is 3668 * statistical, we have to test that we don't drop below 3669 * the minimum feasible timer (which is 2 ticks). 3670 */ 3671 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), 3672 max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX); 3673 3674 /* 3675 * We received an ack for a packet that wasn't retransmitted; 3676 * it is probably safe to discard any error indications we've 3677 * received recently. This isn't quite right, but close enough 3678 * for now (a route might have failed after we sent a segment, 3679 * and the return path might not be symmetrical). 3680 */ 3681 tp->t_softerror = 0; 3682 } 3683 3684 /* 3685 * Determine a reasonable value for maxseg size. 3686 * If the route is known, check route for mtu. 3687 * If none, use an mss that can be handled on the outgoing interface 3688 * without forcing IP to fragment. If no route is found, route has no mtu, 3689 * or the destination isn't local, use a default, hopefully conservative 3690 * size (usually 512 or the default IP max size, but no more than the mtu 3691 * of the interface), as we can't discover anything about intervening 3692 * gateways or networks. We also initialize the congestion/slow start 3693 * window to be a single segment if the destination isn't local. 3694 * While looking at the routing entry, we also initialize other path-dependent 3695 * parameters from pre-set or cached values in the routing entry. 3696 * 3697 * NOTE that resulting t_maxseg doesn't include space for TCP options or 3698 * IP options, e.g. IPSEC data, since length of this data may vary, and 3699 * thus it is calculated for every segment separately in tcp_output(). 3700 * 3701 * NOTE that this routine is only called when we process an incoming 3702 * segment, or an ICMP need fragmentation datagram. Outgoing SYN/ACK MSS 3703 * settings are handled in tcp_mssopt(). 3704 */ 3705 void 3706 tcp_mss_update(struct tcpcb *tp, int offer, int mtuoffer, 3707 struct hc_metrics_lite *metricptr, struct tcp_ifcap *cap) 3708 { 3709 int mss = 0; 3710 uint32_t maxmtu = 0; 3711 struct inpcb *inp = tptoinpcb(tp); 3712 struct hc_metrics_lite metrics; 3713 #ifdef INET6 3714 int isipv6 = ((inp->inp_vflag & INP_IPV6) != 0) ? 1 : 0; 3715 size_t min_protoh = isipv6 ? 3716 sizeof (struct ip6_hdr) + sizeof (struct tcphdr) : 3717 sizeof (struct tcpiphdr); 3718 #else 3719 size_t min_protoh = sizeof(struct tcpiphdr); 3720 #endif 3721 3722 INP_WLOCK_ASSERT(inp); 3723 3724 if (tp->t_port) 3725 min_protoh += V_tcp_udp_tunneling_overhead; 3726 if (mtuoffer != -1) { 3727 KASSERT(offer == -1, ("%s: conflict", __func__)); 3728 offer = mtuoffer - min_protoh; 3729 } 3730 3731 /* Initialize. */ 3732 #ifdef INET6 3733 if (isipv6) { 3734 maxmtu = tcp_maxmtu6(&inp->inp_inc, cap); 3735 tp->t_maxseg = V_tcp_v6mssdflt; 3736 } 3737 #endif 3738 #if defined(INET) && defined(INET6) 3739 else 3740 #endif 3741 #ifdef INET 3742 { 3743 maxmtu = tcp_maxmtu(&inp->inp_inc, cap); 3744 tp->t_maxseg = V_tcp_mssdflt; 3745 } 3746 #endif 3747 3748 /* 3749 * No route to sender, stay with default mss and return. 3750 */ 3751 if (maxmtu == 0) { 3752 /* 3753 * In case we return early we need to initialize metrics 3754 * to a defined state as tcp_hc_get() would do for us 3755 * if there was no cache hit. 3756 */ 3757 if (metricptr != NULL) 3758 bzero(metricptr, sizeof(struct hc_metrics_lite)); 3759 return; 3760 } 3761 3762 /* What have we got? */ 3763 switch (offer) { 3764 case 0: 3765 /* 3766 * Offer == 0 means that there was no MSS on the SYN 3767 * segment, in this case we use tcp_mssdflt as 3768 * already assigned to t_maxseg above. 3769 */ 3770 offer = tp->t_maxseg; 3771 break; 3772 3773 case -1: 3774 /* 3775 * Offer == -1 means that we didn't receive SYN yet. 3776 */ 3777 /* FALLTHROUGH */ 3778 3779 default: 3780 /* 3781 * Prevent DoS attack with too small MSS. Round up 3782 * to at least minmss. 3783 */ 3784 offer = max(offer, V_tcp_minmss); 3785 } 3786 3787 /* 3788 * rmx information is now retrieved from tcp_hostcache. 3789 */ 3790 tcp_hc_get(&inp->inp_inc, &metrics); 3791 if (metricptr != NULL) 3792 bcopy(&metrics, metricptr, sizeof(struct hc_metrics_lite)); 3793 3794 /* 3795 * If there's a discovered mtu in tcp hostcache, use it. 3796 * Else, use the link mtu. 3797 */ 3798 if (metrics.rmx_mtu) 3799 mss = min(metrics.rmx_mtu, maxmtu) - min_protoh; 3800 else { 3801 #ifdef INET6 3802 if (isipv6) { 3803 mss = maxmtu - min_protoh; 3804 if (!V_path_mtu_discovery && 3805 !in6_localaddr(&inp->in6p_faddr)) 3806 mss = min(mss, V_tcp_v6mssdflt); 3807 } 3808 #endif 3809 #if defined(INET) && defined(INET6) 3810 else 3811 #endif 3812 #ifdef INET 3813 { 3814 mss = maxmtu - min_protoh; 3815 if (!V_path_mtu_discovery && 3816 !in_localaddr(inp->inp_faddr)) 3817 mss = min(mss, V_tcp_mssdflt); 3818 } 3819 #endif 3820 /* 3821 * XXX - The above conditional (mss = maxmtu - min_protoh) 3822 * probably violates the TCP spec. 3823 * The problem is that, since we don't know the 3824 * other end's MSS, we are supposed to use a conservative 3825 * default. But, if we do that, then MTU discovery will 3826 * never actually take place, because the conservative 3827 * default is much less than the MTUs typically seen 3828 * on the Internet today. For the moment, we'll sweep 3829 * this under the carpet. 3830 * 3831 * The conservative default might not actually be a problem 3832 * if the only case this occurs is when sending an initial 3833 * SYN with options and data to a host we've never talked 3834 * to before. Then, they will reply with an MSS value which 3835 * will get recorded and the new parameters should get 3836 * recomputed. For Further Study. 3837 */ 3838 } 3839 mss = min(mss, offer); 3840 3841 /* 3842 * Sanity check: make sure that maxseg will be large 3843 * enough to allow some data on segments even if the 3844 * all the option space is used (40bytes). Otherwise 3845 * funny things may happen in tcp_output. 3846 * 3847 * XXXGL: shouldn't we reserve space for IP/IPv6 options? 3848 */ 3849 mss = max(mss, 64); 3850 3851 tp->t_maxseg = mss; 3852 } 3853 3854 void 3855 tcp_mss(struct tcpcb *tp, int offer) 3856 { 3857 int mss; 3858 uint32_t bufsize; 3859 struct inpcb *inp = tptoinpcb(tp); 3860 struct socket *so; 3861 struct hc_metrics_lite metrics; 3862 struct tcp_ifcap cap; 3863 3864 KASSERT(tp != NULL, ("%s: tp == NULL", __func__)); 3865 3866 bzero(&cap, sizeof(cap)); 3867 tcp_mss_update(tp, offer, -1, &metrics, &cap); 3868 3869 mss = tp->t_maxseg; 3870 3871 /* 3872 * If there's a pipesize, change the socket buffer to that size, 3873 * don't change if sb_hiwat is different than default (then it 3874 * has been changed on purpose with setsockopt). 3875 * Make the socket buffers an integral number of mss units; 3876 * if the mss is larger than the socket buffer, decrease the mss. 3877 */ 3878 so = inp->inp_socket; 3879 SOCKBUF_LOCK(&so->so_snd); 3880 if ((so->so_snd.sb_hiwat == V_tcp_sendspace) && metrics.rmx_sendpipe) 3881 bufsize = metrics.rmx_sendpipe; 3882 else 3883 bufsize = so->so_snd.sb_hiwat; 3884 if (bufsize < mss) 3885 mss = bufsize; 3886 else { 3887 bufsize = roundup(bufsize, mss); 3888 if (bufsize > sb_max) 3889 bufsize = sb_max; 3890 if (bufsize > so->so_snd.sb_hiwat) 3891 (void)sbreserve_locked(so, SO_SND, bufsize, NULL); 3892 } 3893 SOCKBUF_UNLOCK(&so->so_snd); 3894 /* 3895 * Sanity check: make sure that maxseg will be large 3896 * enough to allow some data on segments even if the 3897 * all the option space is used (40bytes). Otherwise 3898 * funny things may happen in tcp_output. 3899 * 3900 * XXXGL: shouldn't we reserve space for IP/IPv6 options? 3901 */ 3902 tp->t_maxseg = max(mss, 64); 3903 3904 SOCKBUF_LOCK(&so->so_rcv); 3905 if ((so->so_rcv.sb_hiwat == V_tcp_recvspace) && metrics.rmx_recvpipe) 3906 bufsize = metrics.rmx_recvpipe; 3907 else 3908 bufsize = so->so_rcv.sb_hiwat; 3909 if (bufsize > mss) { 3910 bufsize = roundup(bufsize, mss); 3911 if (bufsize > sb_max) 3912 bufsize = sb_max; 3913 if (bufsize > so->so_rcv.sb_hiwat) 3914 (void)sbreserve_locked(so, SO_RCV, bufsize, NULL); 3915 } 3916 SOCKBUF_UNLOCK(&so->so_rcv); 3917 3918 /* Check the interface for TSO capabilities. */ 3919 if (cap.ifcap & CSUM_TSO) { 3920 tp->t_flags |= TF_TSO; 3921 tp->t_tsomax = cap.tsomax; 3922 tp->t_tsomaxsegcount = cap.tsomaxsegcount; 3923 tp->t_tsomaxsegsize = cap.tsomaxsegsize; 3924 } 3925 } 3926 3927 /* 3928 * Determine the MSS option to send on an outgoing SYN. 3929 */ 3930 int 3931 tcp_mssopt(struct in_conninfo *inc) 3932 { 3933 int mss = 0; 3934 uint32_t thcmtu = 0; 3935 uint32_t maxmtu = 0; 3936 size_t min_protoh; 3937 3938 KASSERT(inc != NULL, ("tcp_mssopt with NULL in_conninfo pointer")); 3939 3940 #ifdef INET6 3941 if (inc->inc_flags & INC_ISIPV6) { 3942 mss = V_tcp_v6mssdflt; 3943 maxmtu = tcp_maxmtu6(inc, NULL); 3944 min_protoh = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 3945 } 3946 #endif 3947 #if defined(INET) && defined(INET6) 3948 else 3949 #endif 3950 #ifdef INET 3951 { 3952 mss = V_tcp_mssdflt; 3953 maxmtu = tcp_maxmtu(inc, NULL); 3954 min_protoh = sizeof(struct tcpiphdr); 3955 } 3956 #endif 3957 #if defined(INET6) || defined(INET) 3958 thcmtu = tcp_hc_getmtu(inc); /* IPv4 and IPv6 */ 3959 #endif 3960 3961 if (maxmtu && thcmtu) 3962 mss = min(maxmtu, thcmtu) - min_protoh; 3963 else if (maxmtu || thcmtu) 3964 mss = max(maxmtu, thcmtu) - min_protoh; 3965 3966 return (mss); 3967 } 3968 3969 void 3970 tcp_do_prr_ack(struct tcpcb *tp, struct tcphdr *th, struct tcpopt *to, 3971 sackstatus_t sack_changed, u_int *maxsegp) 3972 { 3973 int snd_cnt = 0, limit = 0, del_data = 0, pipe = 0; 3974 u_int maxseg; 3975 3976 INP_WLOCK_ASSERT(tptoinpcb(tp)); 3977 3978 if (*maxsegp == 0) { 3979 *maxsegp = tcp_maxseg(tp); 3980 } 3981 maxseg = *maxsegp; 3982 /* 3983 * Compute the amount of data that this ACK is indicating 3984 * (del_data) and an estimate of how many bytes are in the 3985 * network. 3986 */ 3987 if (tcp_is_sack_recovery(tp, to) || 3988 (IN_CONGRECOVERY(tp->t_flags) && 3989 !IN_FASTRECOVERY(tp->t_flags))) { 3990 del_data = tp->sackhint.delivered_data; 3991 if (V_tcp_do_newsack) 3992 pipe = tcp_compute_pipe(tp); 3993 else 3994 pipe = (tp->snd_nxt - tp->snd_fack) + 3995 tp->sackhint.sack_bytes_rexmit; 3996 } else { 3997 if (tp->sackhint.prr_delivered < (tcprexmtthresh * maxseg + 3998 tp->snd_recover - tp->snd_una)) { 3999 del_data = maxseg; 4000 } 4001 pipe = imax(0, tp->snd_max - tp->snd_una - 4002 imin(INT_MAX / 65536, tp->t_dupacks) * maxseg); 4003 } 4004 tp->sackhint.prr_delivered += del_data; 4005 /* 4006 * Proportional Rate Reduction 4007 */ 4008 if (pipe >= tp->snd_ssthresh) { 4009 if (tp->sackhint.recover_fs == 0) 4010 tp->sackhint.recover_fs = 4011 imax(1, tp->snd_nxt - tp->snd_una); 4012 snd_cnt = howmany((long)tp->sackhint.prr_delivered * 4013 tp->snd_ssthresh, tp->sackhint.recover_fs) - 4014 tp->sackhint.prr_out + maxseg - 1; 4015 } else { 4016 /* 4017 * PRR 6937bis heuristic: 4018 * - A partial ack without SACK block beneath snd_recover 4019 * indicates further loss. 4020 * - An SACK scoreboard update adding a new hole indicates 4021 * further loss, so be conservative and send at most one 4022 * segment. 4023 * - Prevent ACK splitting attacks, by being conservative 4024 * when no new data is acked. 4025 */ 4026 if ((sack_changed == SACK_NEWLOSS) || (del_data == 0)) { 4027 limit = tp->sackhint.prr_delivered - 4028 tp->sackhint.prr_out; 4029 } else { 4030 limit = imax(tp->sackhint.prr_delivered - 4031 tp->sackhint.prr_out, del_data) + 4032 maxseg; 4033 } 4034 snd_cnt = imin((tp->snd_ssthresh - pipe), limit); 4035 } 4036 snd_cnt = imax(snd_cnt, 0) / maxseg; 4037 /* 4038 * Send snd_cnt new data into the network in response to this ack. 4039 * If there is going to be a SACK retransmission, adjust snd_cwnd 4040 * accordingly. 4041 */ 4042 if (IN_FASTRECOVERY(tp->t_flags)) { 4043 if (tcp_is_sack_recovery(tp, to)) { 4044 tp->snd_cwnd = tp->snd_nxt - tp->snd_recover + 4045 tp->sackhint.sack_bytes_rexmit + 4046 (snd_cnt * maxseg); 4047 } else { 4048 tp->snd_cwnd = (tp->snd_max - tp->snd_una) + 4049 (snd_cnt * maxseg); 4050 } 4051 } else if (IN_CONGRECOVERY(tp->t_flags)) { 4052 tp->snd_cwnd = pipe - del_data + (snd_cnt * maxseg); 4053 } 4054 tp->snd_cwnd = imax(maxseg, tp->snd_cwnd); 4055 } 4056 4057 /* 4058 * On a partial ack arrives, force the retransmission of the 4059 * next unacknowledged segment. Do not clear tp->t_dupacks. 4060 * By setting snd_nxt to ti_ack, this forces retransmission timer to 4061 * be started again. 4062 */ 4063 void 4064 tcp_newreno_partial_ack(struct tcpcb *tp, struct tcphdr *th) 4065 { 4066 tcp_seq onxt = tp->snd_nxt; 4067 uint32_t ocwnd = tp->snd_cwnd; 4068 u_int maxseg = tcp_maxseg(tp); 4069 4070 INP_WLOCK_ASSERT(tptoinpcb(tp)); 4071 4072 tcp_timer_activate(tp, TT_REXMT, 0); 4073 tp->t_rtttime = 0; 4074 tp->snd_nxt = th->th_ack; 4075 /* 4076 * Set snd_cwnd to one segment beyond acknowledged offset. 4077 * (tp->snd_una has not yet been updated when this function is called.) 4078 */ 4079 tp->snd_cwnd = maxseg + BYTES_THIS_ACK(tp, th); 4080 tp->t_flags |= TF_ACKNOW; 4081 (void) tcp_output(tp); 4082 tp->snd_cwnd = ocwnd; 4083 if (SEQ_GT(onxt, tp->snd_nxt)) 4084 tp->snd_nxt = onxt; 4085 /* 4086 * Partial window deflation. Relies on fact that tp->snd_una 4087 * not updated yet. 4088 */ 4089 if (tp->snd_cwnd > BYTES_THIS_ACK(tp, th)) 4090 tp->snd_cwnd -= BYTES_THIS_ACK(tp, th); 4091 else 4092 tp->snd_cwnd = 0; 4093 tp->snd_cwnd += maxseg; 4094 } 4095 4096 int 4097 tcp_compute_pipe(struct tcpcb *tp) 4098 { 4099 if (tp->t_fb->tfb_compute_pipe == NULL) { 4100 return (tp->snd_max - tp->snd_una + 4101 tp->sackhint.sack_bytes_rexmit - 4102 tp->sackhint.sacked_bytes - 4103 tp->sackhint.lost_bytes); 4104 } else { 4105 return((*tp->t_fb->tfb_compute_pipe)(tp)); 4106 } 4107 } 4108 4109 uint32_t 4110 tcp_compute_initwnd(uint32_t maxseg) 4111 { 4112 /* 4113 * Calculate the Initial Window, also used as Restart Window 4114 * 4115 * RFC5681 Section 3.1 specifies the default conservative values. 4116 * RFC3390 specifies slightly more aggressive values. 4117 * RFC6928 increases it to ten segments. 4118 * Support for user specified value for initial flight size. 4119 */ 4120 if (V_tcp_initcwnd_segments) 4121 return min(V_tcp_initcwnd_segments * maxseg, 4122 max(2 * maxseg, V_tcp_initcwnd_segments * 1460)); 4123 else if (V_tcp_do_rfc3390) 4124 return min(4 * maxseg, max(2 * maxseg, 4380)); 4125 else { 4126 /* Per RFC5681 Section 3.1 */ 4127 if (maxseg > 2190) 4128 return (2 * maxseg); 4129 else if (maxseg > 1095) 4130 return (3 * maxseg); 4131 else 4132 return (4 * maxseg); 4133 } 4134 } 4135