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 "opt_inet.h" 51 #include "opt_inet6.h" 52 #include "opt_ipsec.h" 53 #include "opt_rss.h" 54 55 #include <sys/param.h> 56 #include <sys/arb.h> 57 #include <sys/kernel.h> 58 #ifdef TCP_HHOOK 59 #include <sys/hhook.h> 60 #endif 61 #include <sys/malloc.h> 62 #include <sys/mbuf.h> 63 #include <sys/proc.h> /* for proc0 declaration */ 64 #include <sys/protosw.h> 65 #include <sys/qmath.h> 66 #include <sys/sdt.h> 67 #include <sys/signalvar.h> 68 #include <sys/socket.h> 69 #include <sys/socketvar.h> 70 #include <sys/sysctl.h> 71 #include <sys/syslog.h> 72 #include <sys/systm.h> 73 #include <sys/stats.h> 74 75 #include <machine/cpu.h> /* before tcp_seq.h, for tcp_random18() */ 76 77 #include <vm/uma.h> 78 79 #include <net/if.h> 80 #include <net/if_var.h> 81 #include <net/route.h> 82 #include <net/rss_config.h> 83 #include <net/vnet.h> 84 85 #define TCPSTATES /* for logging */ 86 87 #include <netinet/in.h> 88 #include <netinet/in_kdtrace.h> 89 #include <netinet/in_pcb.h> 90 #include <netinet/in_rss.h> 91 #include <netinet/in_systm.h> 92 #include <netinet/ip.h> 93 #include <netinet/ip_icmp.h> /* required for icmp_var.h */ 94 #include <netinet/icmp_var.h> /* for ICMP_BANDLIM */ 95 #include <netinet/ip_var.h> 96 #include <netinet/ip_options.h> 97 #include <netinet/ip6.h> 98 #include <netinet/icmp6.h> 99 #include <netinet6/in6_pcb.h> 100 #include <netinet6/in6_rss.h> 101 #include <netinet6/in6_var.h> 102 #include <netinet6/ip6_var.h> 103 #include <netinet6/nd6.h> 104 #include <netinet/tcp.h> 105 #include <netinet/tcp_fsm.h> 106 #include <netinet/tcp_seq.h> 107 #include <netinet/tcp_timer.h> 108 #include <netinet/tcp_var.h> 109 #include <netinet/tcp_log_buf.h> 110 #include <netinet6/tcp6_var.h> 111 #include <netinet/tcpip.h> 112 #include <netinet/cc/cc.h> 113 #include <netinet/tcp_fastopen.h> 114 #include <netinet/tcp_syncache.h> 115 #ifdef TCP_OFFLOAD 116 #include <netinet/tcp_offload.h> 117 #endif 118 #include <netinet/tcp_ecn.h> 119 #include <netinet/udp.h> 120 121 #include <netipsec/ipsec_support.h> 122 123 #include <machine/in_cksum.h> 124 125 #include <security/mac/mac_framework.h> 126 127 const int tcprexmtthresh = 3; 128 129 VNET_DEFINE(int, tcp_log_in_vain) = 0; 130 SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_in_vain, CTLFLAG_VNET | CTLFLAG_RW, 131 &VNET_NAME(tcp_log_in_vain), 0, 132 "Log all incoming TCP segments to closed ports"); 133 134 VNET_DEFINE(int, tcp_bind_all_fibs) = 1; 135 SYSCTL_INT(_net_inet_tcp, OID_AUTO, bind_all_fibs, CTLFLAG_VNET | CTLFLAG_RDTUN, 136 &VNET_NAME(tcp_bind_all_fibs), 0, 137 "Bound sockets receive traffic from all FIBs"); 138 139 VNET_DEFINE(int, blackhole) = 0; 140 #define V_blackhole VNET(blackhole) 141 SYSCTL_INT(_net_inet_tcp, OID_AUTO, blackhole, CTLFLAG_VNET | CTLFLAG_RW, 142 &VNET_NAME(blackhole), 0, 143 "Do not send RST on segments to closed ports"); 144 145 VNET_DEFINE(bool, blackhole_local) = false; 146 #define V_blackhole_local VNET(blackhole_local) 147 SYSCTL_BOOL(_net_inet_tcp, OID_AUTO, blackhole_local, CTLFLAG_VNET | 148 CTLFLAG_RW, &VNET_NAME(blackhole_local), false, 149 "Enforce net.inet.tcp.blackhole for locally originated packets"); 150 151 VNET_DEFINE(int, tcp_delack_enabled) = 1; 152 SYSCTL_INT(_net_inet_tcp, OID_AUTO, delayed_ack, CTLFLAG_VNET | CTLFLAG_RW, 153 &VNET_NAME(tcp_delack_enabled), 0, 154 "Delay ACK to try and piggyback it onto a data packet"); 155 156 VNET_DEFINE(int, drop_synfin) = 0; 157 SYSCTL_INT(_net_inet_tcp, OID_AUTO, drop_synfin, CTLFLAG_VNET | CTLFLAG_RW, 158 &VNET_NAME(drop_synfin), 0, 159 "Drop TCP packets with SYN+FIN set"); 160 161 VNET_DEFINE(int, tcp_do_prr) = 1; 162 SYSCTL_INT(_net_inet_tcp, OID_AUTO, do_prr, CTLFLAG_VNET | CTLFLAG_RW, 163 &VNET_NAME(tcp_do_prr), 1, 164 "Enable Proportional Rate Reduction per RFC 6937"); 165 166 VNET_DEFINE(int, tcp_do_newcwv) = 0; 167 SYSCTL_INT(_net_inet_tcp, OID_AUTO, newcwv, CTLFLAG_VNET | CTLFLAG_RW, 168 &VNET_NAME(tcp_do_newcwv), 0, 169 "Enable New Congestion Window Validation per RFC7661"); 170 171 VNET_DEFINE(int, tcp_do_rfc3042) = 1; 172 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3042, CTLFLAG_VNET | CTLFLAG_RW, 173 &VNET_NAME(tcp_do_rfc3042), 0, 174 "Enable RFC 3042 (Limited Transmit)"); 175 176 VNET_DEFINE(int, tcp_do_rfc3390) = 1; 177 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3390, CTLFLAG_VNET | CTLFLAG_RW, 178 &VNET_NAME(tcp_do_rfc3390), 0, 179 "Enable RFC 3390 (Increasing TCP's Initial Congestion Window)"); 180 181 VNET_DEFINE(int, tcp_initcwnd_segments) = 10; 182 SYSCTL_INT(_net_inet_tcp, OID_AUTO, initcwnd_segments, 183 CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(tcp_initcwnd_segments), 0, 184 "Slow-start flight size (initial congestion window) in number of segments"); 185 186 VNET_DEFINE(int, tcp_do_rfc3465) = 1; 187 SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3465, CTLFLAG_VNET | CTLFLAG_RW, 188 &VNET_NAME(tcp_do_rfc3465), 0, 189 "Enable RFC 3465 (Appropriate Byte Counting)"); 190 191 VNET_DEFINE(int, tcp_abc_l_var) = 2; 192 SYSCTL_INT(_net_inet_tcp, OID_AUTO, abc_l_var, CTLFLAG_VNET | CTLFLAG_RW, 193 &VNET_NAME(tcp_abc_l_var), 2, 194 "Cap the max cwnd increment during slow-start to this number of segments"); 195 196 VNET_DEFINE(int, tcp_insecure_syn) = 0; 197 SYSCTL_INT(_net_inet_tcp, OID_AUTO, insecure_syn, CTLFLAG_VNET | CTLFLAG_RW, 198 &VNET_NAME(tcp_insecure_syn), 0, 199 "Follow RFC793 instead of RFC5961 criteria for accepting SYN packets"); 200 201 VNET_DEFINE(int, tcp_insecure_rst) = 0; 202 SYSCTL_INT(_net_inet_tcp, OID_AUTO, insecure_rst, CTLFLAG_VNET | CTLFLAG_RW, 203 &VNET_NAME(tcp_insecure_rst), 0, 204 "Follow RFC793 instead of RFC5961 criteria for accepting RST packets"); 205 206 VNET_DEFINE(int, tcp_insecure_ack) = 0; 207 SYSCTL_INT(_net_inet_tcp, OID_AUTO, insecure_ack, CTLFLAG_VNET | CTLFLAG_RW, 208 &VNET_NAME(tcp_insecure_ack), 0, 209 "Follow RFC793 criteria for validating SEG.ACK"); 210 211 VNET_DEFINE(int, tcp_recvspace) = 1024*64; 212 #define V_tcp_recvspace VNET(tcp_recvspace) 213 SYSCTL_INT(_net_inet_tcp, TCPCTL_RECVSPACE, recvspace, CTLFLAG_VNET | CTLFLAG_RW, 214 &VNET_NAME(tcp_recvspace), 0, "Initial receive socket buffer size"); 215 216 VNET_DEFINE(int, tcp_do_autorcvbuf) = 1; 217 SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_auto, CTLFLAG_VNET | CTLFLAG_RW, 218 &VNET_NAME(tcp_do_autorcvbuf), 0, 219 "Enable automatic receive buffer sizing"); 220 221 VNET_DEFINE(int, tcp_autorcvbuf_max) = 8*1024*1024; 222 SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_max, CTLFLAG_VNET | CTLFLAG_RW, 223 &VNET_NAME(tcp_autorcvbuf_max), 0, 224 "Max size of automatic receive buffer"); 225 226 VNET_DEFINE(struct inpcbinfo, tcbinfo); 227 228 /* 229 * TCP statistics are stored in an array of counter(9)s, which size matches 230 * size of struct tcpstat. TCP running connection count is a regular array. 231 */ 232 VNET_PCPUSTAT_DEFINE(struct tcpstat, tcpstat); 233 SYSCTL_VNET_PCPUSTAT(_net_inet_tcp, TCPCTL_STATS, stats, struct tcpstat, 234 tcpstat, "TCP statistics (struct tcpstat, netinet/tcp_var.h)"); 235 VNET_DEFINE(counter_u64_t, tcps_states[TCP_NSTATES]); 236 SYSCTL_COUNTER_U64_ARRAY(_net_inet_tcp, TCPCTL_STATES, states, CTLFLAG_RD | 237 CTLFLAG_VNET, &VNET_NAME(tcps_states)[0], TCP_NSTATES, 238 "TCP connection counts by TCP state"); 239 240 /* 241 * Kernel module interface for updating tcpstat. The first argument is an index 242 * into tcpstat treated as an array. 243 */ 244 void 245 kmod_tcpstat_add(int statnum, int val) 246 { 247 248 counter_u64_add(VNET(tcpstat)[statnum], val); 249 } 250 251 /* 252 * Make sure that we only start a SACK loss recovery when 253 * receiving a duplicate ACK with a SACK block, and also 254 * complete SACK loss recovery in case the other end 255 * reneges. 256 */ 257 static bool inline 258 tcp_is_sack_recovery(struct tcpcb *tp, struct tcpopt *to) 259 { 260 return ((tp->t_flags & TF_SACK_PERMIT) && 261 ((to->to_flags & TOF_SACK) || 262 (!TAILQ_EMPTY(&tp->snd_holes)))); 263 } 264 265 #ifdef TCP_HHOOK 266 /* 267 * Wrapper for the TCP established input helper hook. 268 */ 269 void 270 hhook_run_tcp_est_in(struct tcpcb *tp, struct tcphdr *th, struct tcpopt *to) 271 { 272 struct tcp_hhook_data hhook_data; 273 274 if (V_tcp_hhh[HHOOK_TCP_EST_IN]->hhh_nhooks > 0) { 275 hhook_data.tp = tp; 276 hhook_data.th = th; 277 hhook_data.to = to; 278 279 hhook_run_hooks(V_tcp_hhh[HHOOK_TCP_EST_IN], &hhook_data, 280 &tp->t_osd); 281 } 282 } 283 #endif 284 285 /* 286 * CC wrapper hook functions 287 */ 288 void 289 cc_ack_received(struct tcpcb *tp, struct tcphdr *th, uint16_t nsegs, 290 uint16_t type) 291 { 292 #ifdef STATS 293 int32_t gput; 294 #endif 295 296 INP_WLOCK_ASSERT(tptoinpcb(tp)); 297 298 tp->t_ccv.nsegs = nsegs; 299 tp->t_ccv.bytes_this_ack = BYTES_THIS_ACK(tp, th); 300 if ((!V_tcp_do_newcwv && (tp->snd_cwnd <= tp->snd_wnd)) || 301 (V_tcp_do_newcwv && (tp->snd_cwnd <= tp->snd_wnd) && 302 (tp->snd_cwnd < (tcp_compute_pipe(tp) * 2)))) 303 tp->t_ccv.flags |= CCF_CWND_LIMITED; 304 else 305 tp->t_ccv.flags &= ~CCF_CWND_LIMITED; 306 307 if (type == CC_ACK) { 308 #ifdef STATS 309 stats_voi_update_abs_s32(tp->t_stats, VOI_TCP_CALCFRWINDIFF, 310 ((int32_t)tp->snd_cwnd) - tp->snd_wnd); 311 if (!IN_RECOVERY(tp->t_flags)) 312 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_ACKLEN, 313 tp->t_ccv.bytes_this_ack / (tcp_maxseg(tp) * nsegs)); 314 if ((tp->t_flags & TF_GPUTINPROG) && 315 SEQ_GEQ(th->th_ack, tp->gput_ack)) { 316 /* 317 * Compute goodput in bits per millisecond. 318 */ 319 gput = (((int64_t)SEQ_SUB(th->th_ack, tp->gput_seq)) << 3) / 320 max(1, tcp_ts_getticks() - tp->gput_ts); 321 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_GPUT, 322 gput); 323 /* 324 * XXXLAS: This is a temporary hack, and should be 325 * chained off VOI_TCP_GPUT when stats(9) grows an API 326 * to deal with chained VOIs. 327 */ 328 if (tp->t_stats_gput_prev > 0) 329 stats_voi_update_abs_s32(tp->t_stats, 330 VOI_TCP_GPUT_ND, 331 ((gput - tp->t_stats_gput_prev) * 100) / 332 tp->t_stats_gput_prev); 333 tp->t_flags &= ~TF_GPUTINPROG; 334 tp->t_stats_gput_prev = gput; 335 } 336 #endif /* STATS */ 337 if (tp->snd_cwnd > tp->snd_ssthresh) { 338 tp->t_bytes_acked += tp->t_ccv.bytes_this_ack; 339 if (tp->t_bytes_acked >= tp->snd_cwnd) { 340 tp->t_bytes_acked -= tp->snd_cwnd; 341 tp->t_ccv.flags |= CCF_ABC_SENTAWND; 342 } 343 } else { 344 tp->t_ccv.flags &= ~CCF_ABC_SENTAWND; 345 tp->t_bytes_acked = 0; 346 } 347 } 348 349 if (CC_ALGO(tp)->ack_received != NULL) { 350 /* XXXLAS: Find a way to live without this */ 351 tp->t_ccv.curack = th->th_ack; 352 CC_ALGO(tp)->ack_received(&tp->t_ccv, type); 353 } 354 #ifdef STATS 355 stats_voi_update_abs_ulong(tp->t_stats, VOI_TCP_LCWIN, tp->snd_cwnd); 356 #endif 357 } 358 359 void 360 cc_conn_init(struct tcpcb *tp) 361 { 362 struct hc_metrics_lite metrics; 363 struct inpcb *inp = tptoinpcb(tp); 364 u_int maxseg; 365 int rtt; 366 367 INP_WLOCK_ASSERT(inp); 368 369 tcp_hc_get(&inp->inp_inc, &metrics); 370 maxseg = tcp_maxseg(tp); 371 372 if (tp->t_srtt == 0 && (rtt = metrics.hc_rtt)) { 373 tp->t_srtt = rtt; 374 TCPSTAT_INC(tcps_usedrtt); 375 if (metrics.hc_rttvar) { 376 tp->t_rttvar = metrics.hc_rttvar; 377 TCPSTAT_INC(tcps_usedrttvar); 378 } else { 379 /* default variation is +- 1 rtt */ 380 tp->t_rttvar = 381 tp->t_srtt * TCP_RTTVAR_SCALE / TCP_RTT_SCALE; 382 } 383 TCPT_RANGESET(tp->t_rxtcur, 384 ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1, 385 tp->t_rttmin, tcp_rexmit_max); 386 } 387 if (metrics.hc_ssthresh) { 388 /* 389 * There's some sort of gateway or interface 390 * buffer limit on the path. Use this to set 391 * the slow start threshold, but set the 392 * threshold to no less than 2*mss. 393 */ 394 tp->snd_ssthresh = max(2 * maxseg, metrics.hc_ssthresh); 395 TCPSTAT_INC(tcps_usedssthresh); 396 } 397 398 /* 399 * Set the initial slow-start flight size. 400 * 401 * If a SYN or SYN/ACK was lost and retransmitted, we have to 402 * reduce the initial CWND to one segment as congestion is likely 403 * requiring us to be cautious. 404 */ 405 if (tp->snd_cwnd == 1) 406 tp->snd_cwnd = maxseg; /* SYN(-ACK) lost */ 407 else 408 tp->snd_cwnd = tcp_compute_initwnd(maxseg); 409 410 if (CC_ALGO(tp)->conn_init != NULL) 411 CC_ALGO(tp)->conn_init(&tp->t_ccv); 412 } 413 414 void inline 415 cc_cong_signal(struct tcpcb *tp, struct tcphdr *th, uint32_t type) 416 { 417 INP_WLOCK_ASSERT(tptoinpcb(tp)); 418 419 #ifdef STATS 420 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_CSIG, type); 421 #endif 422 423 switch(type) { 424 case CC_NDUPACK: 425 if (!IN_FASTRECOVERY(tp->t_flags)) { 426 tp->snd_recover = tp->snd_max; 427 if (tp->t_flags2 & TF2_ECN_PERMIT) 428 tp->t_flags2 |= TF2_ECN_SND_CWR; 429 } 430 break; 431 case CC_ECN: 432 if (!IN_CONGRECOVERY(tp->t_flags) || 433 /* 434 * Allow ECN reaction on ACK to CWR, if 435 * that data segment was also CE marked. 436 */ 437 SEQ_GEQ(th->th_ack, tp->snd_recover)) { 438 EXIT_CONGRECOVERY(tp->t_flags); 439 TCPSTAT_INC(tcps_ecn_rcwnd); 440 tp->snd_recover = tp->snd_max + 1; 441 if (tp->t_flags2 & TF2_ECN_PERMIT) 442 tp->t_flags2 |= TF2_ECN_SND_CWR; 443 } 444 break; 445 case CC_RTO: 446 tp->t_dupacks = 0; 447 tp->t_bytes_acked = 0; 448 EXIT_RECOVERY(tp->t_flags); 449 if (tp->t_flags2 & TF2_ECN_PERMIT) 450 tp->t_flags2 |= TF2_ECN_SND_CWR; 451 break; 452 case CC_RTO_ERR: 453 TCPSTAT_INC(tcps_sndrexmitbad); 454 /* RTO was unnecessary, so reset everything. */ 455 tp->snd_cwnd = tp->snd_cwnd_prev; 456 tp->snd_ssthresh = tp->snd_ssthresh_prev; 457 tp->snd_recover = tp->snd_recover_prev; 458 if (tp->t_flags & TF_WASFRECOVERY) 459 ENTER_FASTRECOVERY(tp->t_flags); 460 if (tp->t_flags & TF_WASCRECOVERY) 461 ENTER_CONGRECOVERY(tp->t_flags); 462 tp->snd_nxt = tp->snd_max; 463 tp->t_flags &= ~TF_PREVVALID; 464 tp->t_rxtshift = 0; 465 tp->t_badrxtwin = 0; 466 break; 467 } 468 if (SEQ_LT(tp->snd_fack, tp->snd_una) || 469 SEQ_GT(tp->snd_fack, tp->snd_max)) { 470 tp->snd_fack = tp->snd_una; 471 } 472 473 if (CC_ALGO(tp)->cong_signal != NULL) { 474 if (th != NULL) 475 tp->t_ccv.curack = th->th_ack; 476 CC_ALGO(tp)->cong_signal(&tp->t_ccv, type); 477 } 478 } 479 480 void inline 481 cc_post_recovery(struct tcpcb *tp, struct tcphdr *th) 482 { 483 INP_WLOCK_ASSERT(tptoinpcb(tp)); 484 485 if (CC_ALGO(tp)->post_recovery != NULL) { 486 if (SEQ_LT(tp->snd_fack, th->th_ack) || 487 SEQ_GT(tp->snd_fack, tp->snd_max)) { 488 tp->snd_fack = th->th_ack; 489 } 490 tp->t_ccv.curack = th->th_ack; 491 CC_ALGO(tp)->post_recovery(&tp->t_ccv); 492 } 493 EXIT_RECOVERY(tp->t_flags); 494 495 tp->t_bytes_acked = 0; 496 tp->sackhint.delivered_data = 0; 497 tp->sackhint.prr_delivered = 0; 498 tp->sackhint.prr_out = 0; 499 tp->snd_cwnd = tp->snd_ssthresh; 500 } 501 502 /* 503 * Indicate whether this ack should be delayed. We can delay the ack if 504 * following conditions are met: 505 * - There is no delayed ack timer in progress. 506 * - Our last ack wasn't a 0-sized window. We never want to delay 507 * the ack that opens up a 0-sized window. 508 * - LRO wasn't used for this segment. We make sure by checking that the 509 * segment size is not larger than the MSS. 510 */ 511 #define DELAY_ACK(tp, tlen) \ 512 ((!tcp_timer_active(tp, TT_DELACK) && \ 513 (tp->t_flags & TF_RXWIN0SENT) == 0) && \ 514 (tlen <= tp->t_maxseg) && \ 515 (V_tcp_delack_enabled || (tp->t_flags & TF_NEEDSYN))) 516 517 void inline 518 cc_ecnpkt_handler_flags(struct tcpcb *tp, uint16_t flags, uint8_t iptos) 519 { 520 INP_WLOCK_ASSERT(tptoinpcb(tp)); 521 522 if (CC_ALGO(tp)->ecnpkt_handler != NULL) { 523 switch (iptos & IPTOS_ECN_MASK) { 524 case IPTOS_ECN_CE: 525 tp->t_ccv.flags |= CCF_IPHDR_CE; 526 break; 527 case IPTOS_ECN_ECT0: 528 /* FALLTHROUGH */ 529 case IPTOS_ECN_ECT1: 530 /* FALLTHROUGH */ 531 case IPTOS_ECN_NOTECT: 532 tp->t_ccv.flags &= ~CCF_IPHDR_CE; 533 break; 534 } 535 536 if (flags & TH_CWR) 537 tp->t_ccv.flags |= CCF_TCPHDR_CWR; 538 else 539 tp->t_ccv.flags &= ~CCF_TCPHDR_CWR; 540 541 CC_ALGO(tp)->ecnpkt_handler(&tp->t_ccv); 542 543 if (((tp->t_state == TCPS_ESTABLISHED) || 544 (tp->t_state == TCPS_FIN_WAIT_1) || 545 (tp->t_state == TCPS_FIN_WAIT_2)) && 546 (tp->t_ccv.flags & CCF_ACKNOW)) { 547 tp->t_flags |= TF_ACKNOW; 548 tp->t_ccv.flags &= ~CCF_ACKNOW; 549 } 550 } 551 } 552 553 void inline 554 cc_ecnpkt_handler(struct tcpcb *tp, struct tcphdr *th, uint8_t iptos) 555 { 556 cc_ecnpkt_handler_flags(tp, tcp_get_flags(th), iptos); 557 } 558 559 /* 560 * TCP input handling is split into multiple parts: 561 * tcp6_input is a thin wrapper around tcp_input for the extended 562 * ip6_protox[] call format in ip6_input 563 * tcp_input handles primary segment validation, inpcb lookup and 564 * SYN processing on listen sockets 565 * tcp_do_segment processes the ACK and text of the segment for 566 * establishing, established and closing connections 567 */ 568 #ifdef INET6 569 int 570 tcp6_input_with_port(struct mbuf **mp, int *offp, int proto, uint16_t port) 571 { 572 struct mbuf *m; 573 574 m = *mp; 575 if (m->m_len < *offp + sizeof(struct tcphdr)) { 576 m = m_pullup(m, *offp + sizeof(struct tcphdr)); 577 if (m == NULL) { 578 *mp = m; 579 TCPSTAT_INC(tcps_rcvshort); 580 return (IPPROTO_DONE); 581 } 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 lookupflag; 616 uint8_t iptos; 617 struct m_tag *fwd_tag = NULL; 618 #ifdef INET6 619 struct ip6_hdr *ip6 = NULL; 620 int isipv6; 621 #else 622 const void *ip6 = NULL; 623 #endif /* INET6 */ 624 struct tcpopt to; /* options in this segment */ 625 char *s = NULL; /* address and port logging */ 626 bool closed_port = false; /* segment is hitting a closed port */ 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 if (m->m_pkthdr.csum_flags & CSUM_IP6_TCP) { 656 /* 657 * Packet from local host (maybe from a VM). 658 * Checksum not required. 659 */ 660 th->th_sum = 0; 661 } else 662 th->th_sum = in6_cksum(m, IPPROTO_TCP, off0, tlen); 663 if (th->th_sum) { 664 TCPSTAT_INC(tcps_rcvbadsum); 665 goto drop; 666 } 667 skip6_csum: 668 /* 669 * Be proactive about unspecified IPv6 address in source. 670 * As we use all-zero to indicate unbounded/unconnected pcb, 671 * unspecified IPv6 address can be used to confuse us. 672 * 673 * Note that packets with unspecified IPv6 destination is 674 * already dropped in ip6_input. 675 */ 676 KASSERT(!IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_dst), 677 ("%s: unspecified destination v6 address", __func__)); 678 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { 679 IP6STAT_INC(ip6s_badscope); /* XXX */ 680 goto drop; 681 } 682 iptos = IPV6_TRAFFIC_CLASS(ip6); 683 } 684 #endif 685 #if defined(INET) && defined(INET6) 686 else 687 #endif 688 #ifdef INET 689 { 690 /* 691 * Get IP and TCP header together in first mbuf. 692 * Note: IP leaves IP header in first mbuf. 693 */ 694 if (off0 > sizeof (struct ip)) { 695 ip_stripoptions(m); 696 off0 = sizeof(struct ip); 697 } 698 if (m->m_len < sizeof (struct tcpiphdr)) { 699 if ((m = m_pullup(m, sizeof (struct tcpiphdr))) 700 == NULL) { 701 TCPSTAT_INC(tcps_rcvshort); 702 return (IPPROTO_DONE); 703 } 704 } 705 ip = mtod(m, struct ip *); 706 th = (struct tcphdr *)((caddr_t)ip + off0); 707 tlen = ntohs(ip->ip_len) - off0; 708 709 iptos = ip->ip_tos; 710 if (port) 711 goto skip_csum; 712 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) { 713 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) 714 th->th_sum = m->m_pkthdr.csum_data; 715 else 716 th->th_sum = in_pseudo(ip->ip_src.s_addr, 717 ip->ip_dst.s_addr, 718 htonl(m->m_pkthdr.csum_data + tlen + 719 IPPROTO_TCP)); 720 th->th_sum ^= 0xffff; 721 } else if (m->m_pkthdr.csum_flags & CSUM_IP_TCP) { 722 /* 723 * Packet from local host (maybe from a VM). 724 * Checksum not required. 725 */ 726 th->th_sum = 0; 727 } else { 728 struct ipovly *ipov = (struct ipovly *)ip; 729 730 /* 731 * Checksum extended TCP header and data. 732 */ 733 len = off0 + tlen; 734 ipttl = ip->ip_ttl; 735 bzero(ipov->ih_x1, sizeof(ipov->ih_x1)); 736 ipov->ih_len = htons(tlen); 737 th->th_sum = in_cksum(m, len); 738 /* Reset length for SDT probes. */ 739 ip->ip_len = htons(len); 740 /* Reset TOS bits */ 741 ip->ip_tos = iptos; 742 /* Re-initialization for later version check */ 743 ip->ip_ttl = ipttl; 744 ip->ip_v = IPVERSION; 745 ip->ip_hl = off0 >> 2; 746 } 747 skip_csum: 748 if (th->th_sum && (port == 0)) { 749 TCPSTAT_INC(tcps_rcvbadsum); 750 goto drop; 751 } 752 KASSERT(ip->ip_dst.s_addr != INADDR_ANY, 753 ("%s: unspecified destination v4 address", __func__)); 754 if (__predict_false(ip->ip_src.s_addr == INADDR_ANY)) { 755 IPSTAT_INC(ips_badaddr); 756 goto drop; 757 } 758 } 759 #endif /* INET */ 760 761 /* 762 * Check that TCP offset makes sense, 763 * pull out TCP options and adjust length. XXX 764 */ 765 off = th->th_off << 2; 766 if (off < sizeof (struct tcphdr) || off > tlen) { 767 TCPSTAT_INC(tcps_rcvbadoff); 768 goto drop; 769 } 770 tlen -= off; /* tlen is used instead of ti->ti_len */ 771 if (off > sizeof (struct tcphdr)) { 772 #ifdef INET6 773 if (isipv6) { 774 if (m->m_len < off0 + off) { 775 m = m_pullup(m, off0 + off); 776 if (m == NULL) { 777 TCPSTAT_INC(tcps_rcvshort); 778 return (IPPROTO_DONE); 779 } 780 } 781 ip6 = mtod(m, struct ip6_hdr *); 782 th = (struct tcphdr *)((caddr_t)ip6 + off0); 783 } 784 #endif 785 #if defined(INET) && defined(INET6) 786 else 787 #endif 788 #ifdef INET 789 { 790 if (m->m_len < sizeof(struct ip) + off) { 791 if ((m = m_pullup(m, sizeof (struct ip) + off)) 792 == NULL) { 793 TCPSTAT_INC(tcps_rcvshort); 794 return (IPPROTO_DONE); 795 } 796 ip = mtod(m, struct ip *); 797 th = (struct tcphdr *)((caddr_t)ip + off0); 798 } 799 } 800 #endif 801 optlen = off - sizeof (struct tcphdr); 802 optp = (u_char *)(th + 1); 803 } 804 thflags = tcp_get_flags(th); 805 806 /* 807 * Convert TCP protocol specific fields to host format. 808 */ 809 tcp_fields_to_host(th); 810 811 /* 812 * Delay dropping TCP, IP headers, IPv6 ext headers, and TCP options. 813 */ 814 drop_hdrlen = off0 + off; 815 816 /* 817 * Grab info from PACKET_TAG_IPFORWARD tag prepended to the chain. 818 */ 819 if ( 820 #ifdef INET6 821 (isipv6 && (m->m_flags & M_IP6_NEXTHOP)) 822 #ifdef INET 823 || (!isipv6 && (m->m_flags & M_IP_NEXTHOP)) 824 #endif 825 #endif 826 #if defined(INET) && !defined(INET6) 827 (m->m_flags & M_IP_NEXTHOP) 828 #endif 829 ) 830 fwd_tag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL); 831 832 /* 833 * For initial SYN packets we don't need write lock on matching 834 * PCB, be it a listening one or a synchronized one. The packet 835 * shall not modify its state. 836 */ 837 lookupflag = INPLOOKUP_WILDCARD | 838 ((thflags & (TH_ACK|TH_SYN)) == TH_SYN ? 839 INPLOOKUP_RLOCKPCB : INPLOOKUP_WLOCKPCB) | 840 (V_tcp_bind_all_fibs ? 0 : INPLOOKUP_FIB); 841 findpcb: 842 tp = NULL; 843 #ifdef INET6 844 if (isipv6 && fwd_tag != NULL) { 845 struct sockaddr_in6 *next_hop6; 846 847 next_hop6 = (struct sockaddr_in6 *)(fwd_tag + 1); 848 /* 849 * Transparently forwarded. Pretend to be the destination. 850 * Already got one like this? 851 */ 852 inp = in6_pcblookup_mbuf(&V_tcbinfo, 853 &ip6->ip6_src, th->th_sport, &ip6->ip6_dst, th->th_dport, 854 lookupflag & ~INPLOOKUP_WILDCARD, m->m_pkthdr.rcvif, m); 855 if (!inp) { 856 /* 857 * It's new. Try to find the ambushing socket. 858 * Because we've rewritten the destination address, 859 * any hardware-generated hash is ignored. 860 */ 861 inp = in6_pcblookup(&V_tcbinfo, &ip6->ip6_src, 862 th->th_sport, &next_hop6->sin6_addr, 863 next_hop6->sin6_port ? ntohs(next_hop6->sin6_port) : 864 th->th_dport, lookupflag, m->m_pkthdr.rcvif); 865 } 866 } else if (isipv6) { 867 inp = in6_pcblookup_mbuf(&V_tcbinfo, &ip6->ip6_src, 868 th->th_sport, &ip6->ip6_dst, th->th_dport, lookupflag, 869 m->m_pkthdr.rcvif, m); 870 } 871 #endif /* INET6 */ 872 #if defined(INET6) && defined(INET) 873 else 874 #endif 875 #ifdef INET 876 if (fwd_tag != NULL) { 877 struct sockaddr_in *next_hop; 878 879 next_hop = (struct sockaddr_in *)(fwd_tag+1); 880 /* 881 * Transparently forwarded. Pretend to be the destination. 882 * already got one like this? 883 */ 884 inp = in_pcblookup_mbuf(&V_tcbinfo, ip->ip_src, th->th_sport, 885 ip->ip_dst, th->th_dport, lookupflag & ~INPLOOKUP_WILDCARD, 886 m->m_pkthdr.rcvif, m); 887 if (!inp) { 888 /* 889 * It's new. Try to find the ambushing socket. 890 * Because we've rewritten the destination address, 891 * any hardware-generated hash is ignored. 892 */ 893 inp = in_pcblookup(&V_tcbinfo, ip->ip_src, 894 th->th_sport, next_hop->sin_addr, 895 next_hop->sin_port ? ntohs(next_hop->sin_port) : 896 th->th_dport, lookupflag, m->m_pkthdr.rcvif); 897 } 898 } else 899 inp = in_pcblookup_mbuf(&V_tcbinfo, ip->ip_src, 900 th->th_sport, ip->ip_dst, th->th_dport, lookupflag, 901 m->m_pkthdr.rcvif, m); 902 #endif /* INET */ 903 904 /* 905 * If the INPCB does not exist then all data in the incoming 906 * segment is discarded and an appropriate RST is sent back. 907 * XXX MRT Send RST using which routing table? 908 */ 909 if (inp == NULL) { 910 if ((lookupflag & INPLOOKUP_WILDCARD) == 0) { 911 /* We came here after second (safety) lookup. */ 912 MPASS(!closed_port); 913 } else { 914 /* 915 * Log communication attempts to ports that are not 916 * in use. 917 */ 918 if (((V_tcp_log_in_vain == 1 && (thflags & TH_SYN)) || 919 V_tcp_log_in_vain == 2) && 920 (s = tcp_log_vain(NULL, th, (void *)ip, ip6))) { 921 log(LOG_INFO, "%s; %s: Connection attempt " 922 "to closed port\n", s, __func__); 923 } 924 closed_port = true; 925 } 926 goto dropwithreset; 927 } 928 INP_LOCK_ASSERT(inp); 929 930 #if defined(IPSEC) || defined(IPSEC_SUPPORT) 931 #ifdef INET6 932 if (isipv6 && IPSEC_ENABLED(ipv6) && 933 IPSEC_CHECK_POLICY(ipv6, m, inp) != 0) { 934 goto dropunlock; 935 } 936 #ifdef INET 937 else 938 #endif 939 #endif /* INET6 */ 940 #ifdef INET 941 if (IPSEC_ENABLED(ipv4) && 942 IPSEC_CHECK_POLICY(ipv4, m, inp) != 0) { 943 goto dropunlock; 944 } 945 #endif /* INET */ 946 #endif /* IPSEC */ 947 948 /* 949 * Check the minimum TTL for socket. 950 */ 951 if (inp->inp_ip_minttl != 0) { 952 #ifdef INET6 953 if (isipv6) { 954 if (inp->inp_ip_minttl > ip6->ip6_hlim) 955 goto dropunlock; 956 } else 957 #endif 958 if (inp->inp_ip_minttl > ip->ip_ttl) 959 goto dropunlock; 960 } 961 962 tp = intotcpcb(inp); 963 switch (tp->t_state) { 964 case TCPS_TIME_WAIT: 965 /* 966 * A previous connection in TIMEWAIT state is supposed to catch 967 * stray or duplicate segments arriving late. If this segment 968 * was a legitimate new connection attempt, the old INPCB gets 969 * removed and we can try again to find a listening socket. 970 */ 971 tcp_dooptions(&to, optp, optlen, 972 (thflags & TH_SYN) ? TO_SYN : 0); 973 /* 974 * tcp_twcheck unlocks the inp always, and frees the m if fails. 975 */ 976 if (tcp_twcheck(inp, &to, th, m, tlen)) 977 goto findpcb; 978 return (IPPROTO_DONE); 979 case TCPS_CLOSED: 980 /* 981 * The TCPCB may no longer exist if the connection is winding 982 * down or it is in the CLOSED state. Either way we drop the 983 * segment and send an appropriate response. 984 */ 985 closed_port = true; 986 goto dropwithreset; 987 } 988 989 if ((tp->t_port != port) && (tp->t_state > TCPS_LISTEN)) { 990 closed_port = true; 991 goto dropwithreset; 992 } 993 994 #ifdef TCP_OFFLOAD 995 if (tp->t_flags & TF_TOE) { 996 tcp_offload_input(tp, m); 997 m = NULL; /* consumed by the TOE driver */ 998 goto dropunlock; 999 } 1000 #endif 1001 1002 #ifdef MAC 1003 if (mac_inpcb_check_deliver(inp, m)) 1004 goto dropunlock; 1005 #endif 1006 so = inp->inp_socket; 1007 KASSERT(so != NULL, ("%s: so == NULL", __func__)); 1008 /* 1009 * When the socket is accepting connections (the INPCB is in LISTEN 1010 * state) we look into the SYN cache if this is a new connection 1011 * attempt or the completion of a previous one. 1012 */ 1013 KASSERT(tp->t_state == TCPS_LISTEN || !SOLISTENING(so), 1014 ("%s: so accepting but tp %p not listening", __func__, tp)); 1015 if (tp->t_state == TCPS_LISTEN && SOLISTENING(so)) { 1016 struct in_conninfo inc; 1017 1018 bzero(&inc, sizeof(inc)); 1019 #ifdef INET6 1020 if (isipv6) { 1021 inc.inc_flags |= INC_ISIPV6; 1022 if (inp->inp_inc.inc_flags & INC_IPV6MINMTU) 1023 inc.inc_flags |= INC_IPV6MINMTU; 1024 inc.inc6_faddr = ip6->ip6_src; 1025 inc.inc6_laddr = ip6->ip6_dst; 1026 } else 1027 #endif 1028 { 1029 inc.inc_faddr = ip->ip_src; 1030 inc.inc_laddr = ip->ip_dst; 1031 } 1032 inc.inc_fport = th->th_sport; 1033 inc.inc_lport = th->th_dport; 1034 inc.inc_fibnum = so->so_fibnum; 1035 1036 /* 1037 * Check for an existing connection attempt in syncache if 1038 * the flag is only ACK. A successful lookup creates a new 1039 * socket appended to the listen queue in SYN_RECEIVED state. 1040 */ 1041 if ((thflags & (TH_RST|TH_ACK|TH_SYN)) == TH_ACK) { 1042 int result; 1043 1044 /* 1045 * Parse the TCP options here because 1046 * syncookies need access to the reflected 1047 * timestamp. 1048 */ 1049 tcp_dooptions(&to, optp, optlen, 0); 1050 /* 1051 * NB: syncache_expand() doesn't unlock inp. 1052 */ 1053 result = syncache_expand(&inc, &to, th, &so, m, port); 1054 if (result < 0) { 1055 /* 1056 * A failing TCP MD5 signature comparison 1057 * must result in the segment being dropped 1058 * and must not produce any response back 1059 * to the sender. 1060 */ 1061 goto dropunlock; 1062 } else if (result == 0) { 1063 /* 1064 * No syncache entry, or ACK was not for our 1065 * SYN/ACK. Do our protection against double 1066 * ACK. If peer sent us 2 ACKs, then for the 1067 * first one syncache_expand() successfully 1068 * converted syncache entry into a socket, 1069 * while we were waiting on the inpcb lock. We 1070 * don't want to sent RST for the second ACK, 1071 * so we perform second lookup without wildcard 1072 * match, hoping to find the new socket. If 1073 * the ACK is stray indeed, the missing 1074 * INPLOOKUP_WILDCARD flag in lookupflag would 1075 * hint the above code that the lookup was a 1076 * second attempt. 1077 * 1078 * NB: syncache did its own logging 1079 * of the failure cause. 1080 */ 1081 INP_WUNLOCK(inp); 1082 lookupflag &= ~INPLOOKUP_WILDCARD; 1083 goto findpcb; 1084 } 1085 tfo_socket_result: 1086 if (so == NULL) { 1087 /* 1088 * We completed the 3-way handshake 1089 * but could not allocate a socket 1090 * either due to memory shortage, 1091 * listen queue length limits or 1092 * global socket limits. Send RST 1093 * or wait and have the remote end 1094 * retransmit the ACK for another 1095 * try. 1096 */ 1097 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1098 log(LOG_DEBUG, "%s; %s: Listen socket: " 1099 "Socket allocation failed due to " 1100 "limits or memory shortage, %s\n", 1101 s, __func__, 1102 V_tcp_sc_rst_sock_fail ? 1103 "sending RST" : "try again"); 1104 if (V_tcp_sc_rst_sock_fail) { 1105 goto dropwithreset; 1106 } else 1107 goto dropunlock; 1108 } 1109 /* 1110 * Socket is created in state SYN_RECEIVED. 1111 * Unlock the listen socket, lock the newly 1112 * created socket and update the tp variable. 1113 * If we came here via jump to tfo_socket_result, 1114 * then listening socket is read-locked. 1115 */ 1116 INP_UNLOCK(inp); /* listen socket */ 1117 inp = sotoinpcb(so); 1118 /* 1119 * New connection inpcb is already locked by 1120 * syncache_expand(). 1121 */ 1122 INP_WLOCK_ASSERT(inp); 1123 tp = intotcpcb(inp); 1124 KASSERT(tp->t_state == TCPS_SYN_RECEIVED, 1125 ("%s: ", __func__)); 1126 /* 1127 * Process the segment and the data it 1128 * contains. tcp_do_segment() consumes 1129 * the mbuf chain and unlocks the inpcb. 1130 */ 1131 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1132 tp->t_fb->tfb_tcp_do_segment(tp, m, th, drop_hdrlen, 1133 tlen, iptos); 1134 return (IPPROTO_DONE); 1135 } 1136 /* 1137 * Segment flag validation for new connection attempts: 1138 * 1139 * Our (SYN|ACK) response was rejected. 1140 * Check with syncache and remove entry to prevent 1141 * retransmits. 1142 * 1143 * NB: syncache_chkrst does its own logging of failure 1144 * causes. 1145 */ 1146 if (thflags & TH_RST) { 1147 syncache_chkrst(&inc, th, port); 1148 goto dropunlock; 1149 } 1150 /* 1151 * We can't do anything without SYN. 1152 */ 1153 if ((thflags & TH_SYN) == 0) { 1154 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1155 log(LOG_DEBUG, "%s; %s: Listen socket: " 1156 "SYN is missing, segment ignored\n", 1157 s, __func__); 1158 TCPSTAT_INC(tcps_badsyn); 1159 goto dropunlock; 1160 } 1161 /* 1162 * (SYN|ACK) is bogus on a listen socket. 1163 */ 1164 if (thflags & TH_ACK) { 1165 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1166 log(LOG_DEBUG, "%s; %s: Listen socket: " 1167 "SYN|ACK invalid, segment ignored\n", 1168 s, __func__); 1169 TCPSTAT_INC(tcps_badsyn); 1170 goto dropunlock; 1171 } 1172 /* 1173 * If the drop_synfin option is enabled, drop all 1174 * segments with both the SYN and FIN bits set. 1175 * This prevents e.g. nmap from identifying the 1176 * TCP/IP stack. 1177 * XXX: Poor reasoning. nmap has other methods 1178 * and is constantly refining its stack detection 1179 * strategies. 1180 * XXX: This is a violation of the TCP specification 1181 * and was used by RFC1644. 1182 */ 1183 if ((thflags & TH_FIN) && V_drop_synfin) { 1184 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1185 log(LOG_DEBUG, "%s; %s: Listen socket: " 1186 "SYN|FIN segment ignored (based on " 1187 "sysctl setting)\n", s, __func__); 1188 TCPSTAT_INC(tcps_badsyn); 1189 goto dropunlock; 1190 } 1191 /* 1192 * Segment's flags are (SYN) or (SYN|FIN). 1193 * 1194 * TH_PUSH, TH_URG, TH_ECE, TH_CWR are ignored 1195 * as they do not affect the state of the TCP FSM. 1196 * The data pointed to by TH_URG and th_urp is ignored. 1197 */ 1198 KASSERT((thflags & (TH_RST|TH_ACK)) == 0, 1199 ("%s: Listen socket: TH_RST or TH_ACK set", __func__)); 1200 KASSERT(thflags & (TH_SYN), 1201 ("%s: Listen socket: TH_SYN not set", __func__)); 1202 INP_RLOCK_ASSERT(inp); 1203 #ifdef INET6 1204 /* 1205 * If deprecated address is forbidden, 1206 * we do not accept SYN to deprecated interface 1207 * address to prevent any new inbound connection from 1208 * getting established. 1209 * When we do not accept SYN, we send a TCP RST, 1210 * with deprecated source address (instead of dropping 1211 * it). We compromise it as it is much better for peer 1212 * to send a RST, and RST will be the final packet 1213 * for the exchange. 1214 * 1215 * If we do not forbid deprecated addresses, we accept 1216 * the SYN packet. RFC2462 does not suggest dropping 1217 * SYN in this case. 1218 * If we decipher RFC2462 5.5.4, it says like this: 1219 * 1. use of deprecated addr with existing 1220 * communication is okay - "SHOULD continue to be 1221 * used" 1222 * 2. use of it with new communication: 1223 * (2a) "SHOULD NOT be used if alternate address 1224 * with sufficient scope is available" 1225 * (2b) nothing mentioned otherwise. 1226 * Here we fall into (2b) case as we have no choice in 1227 * our source address selection - we must obey the peer. 1228 * 1229 * The wording in RFC2462 is confusing, and there are 1230 * multiple description text for deprecated address 1231 * handling - worse, they are not exactly the same. 1232 * I believe 5.5.4 is the best one, so we follow 5.5.4. 1233 */ 1234 if (isipv6 && !V_ip6_use_deprecated) { 1235 struct in6_ifaddr *ia6; 1236 1237 ia6 = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */, false); 1238 if (ia6 != NULL && 1239 (ia6->ia6_flags & IN6_IFF_DEPRECATED)) { 1240 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1241 log(LOG_DEBUG, "%s; %s: Listen socket: " 1242 "Connection attempt to deprecated " 1243 "IPv6 address rejected\n", 1244 s, __func__); 1245 goto dropwithreset; 1246 } 1247 } 1248 #endif /* INET6 */ 1249 /* 1250 * Basic sanity checks on incoming SYN requests: 1251 * Don't respond if the destination is a link layer 1252 * broadcast according to RFC1122 4.2.3.10, p. 104. 1253 * If it is from this socket it must be forged. 1254 * Don't respond if the source or destination is a 1255 * global or subnet broad- or multicast address. 1256 * Note that it is quite possible to receive unicast 1257 * link-layer packets with a broadcast IP address. Use 1258 * in_ifnet_broadcast() to find them. 1259 */ 1260 if (m->m_flags & (M_BCAST|M_MCAST)) { 1261 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1262 log(LOG_DEBUG, "%s; %s: Listen socket: " 1263 "Connection attempt from broad- or multicast " 1264 "link layer address ignored\n", s, __func__); 1265 goto dropunlock; 1266 } 1267 #ifdef INET6 1268 if (isipv6) { 1269 if (th->th_dport == th->th_sport && 1270 IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, &ip6->ip6_src)) { 1271 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1272 log(LOG_DEBUG, "%s; %s: Listen socket: " 1273 "Connection attempt to/from self " 1274 "ignored\n", s, __func__); 1275 goto dropunlock; 1276 } 1277 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 1278 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) { 1279 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1280 log(LOG_DEBUG, "%s; %s: Listen socket: " 1281 "Connection attempt from/to multicast " 1282 "address ignored\n", s, __func__); 1283 goto dropunlock; 1284 } 1285 } 1286 #endif 1287 #if defined(INET) && defined(INET6) 1288 else 1289 #endif 1290 #ifdef INET 1291 { 1292 if (th->th_dport == th->th_sport && 1293 ip->ip_dst.s_addr == ip->ip_src.s_addr) { 1294 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1295 log(LOG_DEBUG, "%s; %s: Listen socket: " 1296 "Connection attempt from/to self " 1297 "ignored\n", s, __func__); 1298 goto dropunlock; 1299 } 1300 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || 1301 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 1302 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || 1303 in_ifnet_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) { 1304 if ((s = tcp_log_addrs(&inc, th, NULL, NULL))) 1305 log(LOG_DEBUG, "%s; %s: Listen socket: " 1306 "Connection attempt from/to broad- " 1307 "or multicast address ignored\n", 1308 s, __func__); 1309 goto dropunlock; 1310 } 1311 } 1312 #endif 1313 /* 1314 * SYN appears to be valid. Create compressed TCP state 1315 * for syncache. 1316 */ 1317 TCP_PROBE3(debug__input, tp, th, m); 1318 tcp_dooptions(&to, optp, optlen, TO_SYN); 1319 if ((so = syncache_add(&inc, &to, th, inp, so, m, NULL, NULL, 1320 iptos, port)) != NULL) 1321 goto tfo_socket_result; 1322 1323 /* 1324 * Entry added to syncache and mbuf consumed. 1325 * Only the listen socket is unlocked by syncache_add(). 1326 */ 1327 return (IPPROTO_DONE); 1328 } 1329 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 1330 if (tp->t_flags & TF_SIGNATURE) { 1331 tcp_dooptions(&to, optp, optlen, thflags); 1332 if ((to.to_flags & TOF_SIGNATURE) == 0) { 1333 TCPSTAT_INC(tcps_sig_err_nosigopt); 1334 goto dropunlock; 1335 } 1336 if (!TCPMD5_ENABLED() || 1337 TCPMD5_INPUT(m, th, to.to_signature) != 0) 1338 goto dropunlock; 1339 } 1340 #endif 1341 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1342 1343 /* 1344 * Segment belongs to a connection in SYN_SENT, ESTABLISHED or later 1345 * state. tcp_do_segment() always consumes the mbuf chain, unlocks 1346 * the inpcb, and unlocks pcbinfo. 1347 * 1348 * XXXGL: in case of a pure SYN arriving on existing connection 1349 * TCP stacks won't need to modify the PCB, they would either drop 1350 * the segment silently, or send a challenge ACK. However, we try 1351 * to upgrade the lock, because calling convention for stacks is 1352 * write-lock on PCB. If upgrade fails, drop the SYN. 1353 */ 1354 if ((lookupflag & INPLOOKUP_RLOCKPCB) && INP_TRY_UPGRADE(inp) == 0) 1355 goto dropunlock; 1356 1357 tp->t_fb->tfb_tcp_do_segment(tp, m, th, drop_hdrlen, tlen, iptos); 1358 return (IPPROTO_DONE); 1359 1360 dropwithreset: 1361 /* 1362 * When blackholing do not respond with a RST but 1363 * completely ignore the segment and drop it. 1364 */ 1365 if (((!closed_port && V_blackhole == 3) || 1366 (closed_port && 1367 ((V_blackhole == 1 && (thflags & TH_SYN)) || V_blackhole > 1))) && 1368 (V_blackhole_local || ( 1369 #ifdef INET6 1370 isipv6 ? !in6_localip(&ip6->ip6_src) : 1371 #endif 1372 #ifdef INET 1373 !in_localip(ip->ip_src) 1374 #else 1375 true 1376 #endif 1377 ))) 1378 goto dropunlock; 1379 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1380 tcp_dropwithreset(m, th, tp, tlen); 1381 m = NULL; /* mbuf chain got consumed. */ 1382 1383 dropunlock: 1384 if (m != NULL) 1385 TCP_PROBE5(receive, NULL, tp, m, tp, th); 1386 1387 if (inp != NULL) 1388 INP_UNLOCK(inp); 1389 1390 drop: 1391 if (s != NULL) 1392 free(s, M_TCPLOG); 1393 if (m != NULL) 1394 m_freem(m); 1395 return (IPPROTO_DONE); 1396 } 1397 1398 /* 1399 * Automatic sizing of receive socket buffer. Often the send 1400 * buffer size is not optimally adjusted to the actual network 1401 * conditions at hand (delay bandwidth product). Setting the 1402 * buffer size too small limits throughput on links with high 1403 * bandwidth and high delay (eg. trans-continental/oceanic links). 1404 * 1405 * On the receive side the socket buffer memory is only rarely 1406 * used to any significant extent. This allows us to be much 1407 * more aggressive in scaling the receive socket buffer. For 1408 * the case that the buffer space is actually used to a large 1409 * extent and we run out of kernel memory we can simply drop 1410 * the new segments; TCP on the sender will just retransmit it 1411 * later. Setting the buffer size too big may only consume too 1412 * much kernel memory if the application doesn't read() from 1413 * the socket or packet loss or reordering makes use of the 1414 * reassembly queue. 1415 * 1416 * The criteria to step up the receive buffer one notch are: 1417 * 1. Application has not set receive buffer size with 1418 * SO_RCVBUF. Setting SO_RCVBUF clears SB_AUTOSIZE. 1419 * 2. the number of bytes received during 1/2 of an sRTT 1420 * is at least 3/8 of the current socket buffer size. 1421 * 3. receive buffer size has not hit maximal automatic size; 1422 * 1423 * If all of the criteria are met, we increase the socket buffer 1424 * by a 1/2 (bounded by the max). This allows us to keep ahead 1425 * of slow-start but also makes it so our peer never gets limited 1426 * by our rwnd which we then open up causing a burst. 1427 * 1428 * This algorithm does two steps per RTT at most and only if 1429 * we receive a bulk stream w/o packet losses or reorderings. 1430 * Shrinking the buffer during idle times is not necessary as 1431 * it doesn't consume any memory when idle. 1432 * 1433 * TODO: Only step up if the application is actually serving 1434 * the buffer to better manage the socket buffer resources. 1435 */ 1436 int 1437 tcp_autorcvbuf(struct mbuf *m, struct tcphdr *th, struct socket *so, 1438 struct tcpcb *tp, int tlen) 1439 { 1440 int newsize = 0; 1441 1442 if (V_tcp_do_autorcvbuf && (so->so_rcv.sb_flags & SB_AUTOSIZE) && 1443 tp->t_srtt != 0 && tp->rfbuf_ts != 0 && 1444 TCP_TS_TO_TICKS(tcp_ts_getticks() - tp->rfbuf_ts) > 1445 ((tp->t_srtt >> TCP_RTT_SHIFT)/2)) { 1446 if (tp->rfbuf_cnt > ((so->so_rcv.sb_hiwat / 2)/ 4 * 3) && 1447 so->so_rcv.sb_hiwat < V_tcp_autorcvbuf_max) { 1448 newsize = min((so->so_rcv.sb_hiwat + (so->so_rcv.sb_hiwat/2)), V_tcp_autorcvbuf_max); 1449 } 1450 TCP_PROBE6(receive__autoresize, NULL, tp, m, tp, th, newsize); 1451 1452 /* Start over with next RTT. */ 1453 tp->rfbuf_ts = 0; 1454 tp->rfbuf_cnt = 0; 1455 } else { 1456 tp->rfbuf_cnt += tlen; /* add up */ 1457 } 1458 return (newsize); 1459 } 1460 1461 int 1462 tcp_input(struct mbuf **mp, int *offp, int proto) 1463 { 1464 return(tcp_input_with_port(mp, offp, proto, 0)); 1465 } 1466 1467 static void 1468 tcp_handle_wakeup(struct tcpcb *tp) 1469 { 1470 1471 INP_WLOCK_ASSERT(tptoinpcb(tp)); 1472 1473 if (tp->t_flags & TF_WAKESOR) { 1474 struct socket *so = tptosocket(tp); 1475 1476 tp->t_flags &= ~TF_WAKESOR; 1477 SOCK_RECVBUF_LOCK_ASSERT(so); 1478 sorwakeup_locked(so); 1479 } 1480 } 1481 1482 void 1483 tcp_do_segment(struct tcpcb *tp, struct mbuf *m, struct tcphdr *th, 1484 int drop_hdrlen, int tlen, uint8_t iptos) 1485 { 1486 uint16_t thflags; 1487 int acked, ourfinisacked, needoutput = 0; 1488 sackstatus_t sack_changed; 1489 int todrop, win, incforsyn = 0; 1490 uint32_t tiwin; 1491 uint16_t nsegs; 1492 char *s; 1493 struct inpcb *inp = tptoinpcb(tp); 1494 struct socket *so = tptosocket(tp); 1495 struct in_conninfo *inc = &inp->inp_inc; 1496 struct mbuf *mfree; 1497 struct tcpopt to; 1498 int tfo_syn; 1499 u_int maxseg = 0; 1500 uint32_t prev_sacked_bytes = 0; 1501 bool no_data; 1502 1503 no_data = (tlen == 0); 1504 thflags = tcp_get_flags(th); 1505 tp->sackhint.last_sack_ack = 0; 1506 sack_changed = SACK_NOCHANGE; 1507 nsegs = max(1, m->m_pkthdr.lro_nsegs); 1508 1509 NET_EPOCH_ASSERT(); 1510 INP_WLOCK_ASSERT(inp); 1511 KASSERT(tp->t_state > TCPS_LISTEN, ("%s: TCPS_LISTEN", 1512 __func__)); 1513 KASSERT(tp->t_state != TCPS_TIME_WAIT, ("%s: TCPS_TIME_WAIT", 1514 __func__)); 1515 1516 TCP_LOG_EVENT(tp, th, &so->so_rcv, &so->so_snd, TCP_LOG_IN, 0, 1517 tlen, NULL, true); 1518 1519 if ((thflags & TH_SYN) && (thflags & TH_FIN) && V_drop_synfin) { 1520 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1521 log(LOG_DEBUG, "%s; %s: " 1522 "SYN|FIN segment ignored (based on " 1523 "sysctl setting)\n", s, __func__); 1524 free(s, M_TCPLOG); 1525 } 1526 goto drop; 1527 } 1528 1529 /* 1530 * If a segment with the ACK-bit set arrives in the SYN-SENT state 1531 * check SEQ.ACK first. 1532 */ 1533 if ((tp->t_state == TCPS_SYN_SENT) && (thflags & TH_ACK) && 1534 (SEQ_LEQ(th->th_ack, tp->iss) || SEQ_GT(th->th_ack, tp->snd_max))) { 1535 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 1536 goto dropwithreset; 1537 } 1538 1539 /* 1540 * Segment received on connection. 1541 * Reset idle time and keep-alive timer. 1542 * XXX: This should be done after segment 1543 * validation to ignore broken/spoofed segs. 1544 */ 1545 if (tp->t_idle_reduce && 1546 (tp->snd_max == tp->snd_una) && 1547 ((ticks - tp->t_rcvtime) >= tp->t_rxtcur)) 1548 cc_after_idle(tp); 1549 tp->t_rcvtime = ticks; 1550 1551 if (thflags & TH_FIN) 1552 tcp_log_end_status(tp, TCP_EI_STATUS_CLIENT_FIN); 1553 /* 1554 * Scale up the window into a 32-bit value. 1555 * For the SYN_SENT state the scale is zero. 1556 */ 1557 tiwin = th->th_win << tp->snd_scale; 1558 #ifdef STATS 1559 stats_voi_update_abs_ulong(tp->t_stats, VOI_TCP_FRWIN, tiwin); 1560 #endif 1561 1562 /* 1563 * TCP ECN processing. 1564 */ 1565 if (tcp_ecn_input_segment(tp, thflags, tlen, 1566 tcp_packets_this_ack(tp, th->th_ack), 1567 iptos)) 1568 cc_cong_signal(tp, th, CC_ECN); 1569 1570 /* 1571 * Parse options on any incoming segment. 1572 */ 1573 tcp_dooptions(&to, (u_char *)(th + 1), 1574 (th->th_off << 2) - sizeof(struct tcphdr), 1575 (thflags & TH_SYN) ? TO_SYN : 0); 1576 if (tp->t_flags2 & TF2_PROC_SACK_PROHIBIT) { 1577 /* 1578 * We don't look at sack's from the 1579 * peer because the MSS is too small which 1580 * can subject us to an attack. 1581 */ 1582 to.to_flags &= ~TOF_SACK; 1583 } 1584 #if defined(IPSEC_SUPPORT) || defined(TCP_SIGNATURE) 1585 if ((tp->t_flags & TF_SIGNATURE) != 0 && 1586 (to.to_flags & TOF_SIGNATURE) == 0) { 1587 TCPSTAT_INC(tcps_sig_err_sigopt); 1588 /* XXX: should drop? */ 1589 } 1590 #endif 1591 /* 1592 * If echoed timestamp is later than the current time, 1593 * fall back to non RFC1323 RTT calculation. Normalize 1594 * timestamp if syncookies were used when this connection 1595 * was established. 1596 */ 1597 if ((to.to_flags & TOF_TS) && (to.to_tsecr != 0)) { 1598 to.to_tsecr -= tp->ts_offset; 1599 if (TSTMP_GT(to.to_tsecr, tcp_ts_getticks())) { 1600 to.to_tsecr = 0; 1601 } 1602 } 1603 /* 1604 * Process options only when we get SYN/ACK back. The SYN case 1605 * for incoming connections is handled in tcp_syncache. 1606 * According to RFC1323 the window field in a SYN (i.e., a <SYN> 1607 * or <SYN,ACK>) segment itself is never scaled. 1608 * XXX this is traditional behavior, may need to be cleaned up. 1609 */ 1610 if (tp->t_state == TCPS_SYN_SENT && (thflags & TH_SYN)) { 1611 /* Handle parallel SYN for ECN */ 1612 tcp_ecn_input_parallel_syn(tp, thflags, iptos); 1613 if ((to.to_flags & TOF_SCALE) && 1614 (tp->t_flags & TF_REQ_SCALE) && 1615 !(tp->t_flags & TF_NOOPT)) { 1616 tp->t_flags |= TF_RCVD_SCALE; 1617 tp->snd_scale = to.to_wscale; 1618 } else { 1619 tp->t_flags &= ~TF_REQ_SCALE; 1620 } 1621 /* 1622 * Initial send window. It will be updated with 1623 * the next incoming segment to the scaled value. 1624 */ 1625 tp->snd_wnd = th->th_win; 1626 if ((to.to_flags & TOF_TS) && 1627 (tp->t_flags & TF_REQ_TSTMP) && 1628 !(tp->t_flags & TF_NOOPT)) { 1629 tp->t_flags |= TF_RCVD_TSTMP; 1630 tp->ts_recent = to.to_tsval; 1631 tp->ts_recent_age = tcp_ts_getticks(); 1632 } else { 1633 tp->t_flags &= ~TF_REQ_TSTMP; 1634 } 1635 if (to.to_flags & TOF_MSS) { 1636 tcp_mss(tp, to.to_mss); 1637 } 1638 if ((tp->t_flags & TF_SACK_PERMIT) && 1639 (!(to.to_flags & TOF_SACKPERM) || 1640 (tp->t_flags & TF_NOOPT))) { 1641 tp->t_flags &= ~TF_SACK_PERMIT; 1642 } 1643 if (tp->t_flags & TF_FASTOPEN) { 1644 if ((to.to_flags & TOF_FASTOPEN) && 1645 !(tp->t_flags & TF_NOOPT)) { 1646 uint16_t mss; 1647 1648 if (to.to_flags & TOF_MSS) { 1649 mss = to.to_mss; 1650 } else { 1651 if ((inp->inp_vflag & INP_IPV6) != 0) { 1652 mss = TCP6_MSS; 1653 } else { 1654 mss = TCP_MSS; 1655 } 1656 } 1657 tcp_fastopen_update_cache(tp, mss, 1658 to.to_tfo_len, to.to_tfo_cookie); 1659 } else { 1660 tcp_fastopen_disable_path(tp); 1661 } 1662 } 1663 } 1664 1665 /* 1666 * If timestamps were negotiated during SYN/ACK and a 1667 * segment without a timestamp is received, silently drop 1668 * the segment, unless it is a RST segment or missing timestamps are 1669 * tolerated. 1670 * See section 3.2 of RFC 7323. 1671 */ 1672 if ((tp->t_flags & TF_RCVD_TSTMP) && !(to.to_flags & TOF_TS)) { 1673 if (((thflags & TH_RST) != 0) || V_tcp_tolerate_missing_ts) { 1674 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1675 log(LOG_DEBUG, "%s; %s: Timestamp missing, " 1676 "segment processed normally\n", 1677 s, __func__); 1678 free(s, M_TCPLOG); 1679 } 1680 } else { 1681 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1682 log(LOG_DEBUG, "%s; %s: Timestamp missing, " 1683 "segment silently dropped\n", s, __func__); 1684 free(s, M_TCPLOG); 1685 } 1686 goto drop; 1687 } 1688 } 1689 /* 1690 * If timestamps were not negotiated during SYN/ACK and a 1691 * segment with a timestamp is received, ignore the 1692 * timestamp and process the packet normally. 1693 * See section 3.2 of RFC 7323. 1694 */ 1695 if (!(tp->t_flags & TF_RCVD_TSTMP) && (to.to_flags & TOF_TS)) { 1696 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 1697 log(LOG_DEBUG, "%s; %s: Timestamp not expected, " 1698 "segment processed normally\n", s, __func__); 1699 free(s, M_TCPLOG); 1700 } 1701 } 1702 1703 /* 1704 * Header prediction: check for the two common cases 1705 * of a uni-directional data xfer. If the packet has 1706 * no control flags, is in-sequence, the window didn't 1707 * change and we're not retransmitting, it's a 1708 * candidate. If the length is zero and the ack moved 1709 * forward, we're the sender side of the xfer. Just 1710 * free the data acked & wake any higher level process 1711 * that was blocked waiting for space. If the length 1712 * is non-zero and the ack didn't move, we're the 1713 * receiver side. If we're getting packets in-order 1714 * (the reassembly queue is empty), add the data to 1715 * the socket buffer and note that we need a delayed ack. 1716 * Make sure that the hidden state-flags are also off. 1717 * Since we check for TCPS_ESTABLISHED first, it can only 1718 * be TH_NEEDSYN. 1719 */ 1720 if (tp->t_state == TCPS_ESTABLISHED && 1721 th->th_seq == tp->rcv_nxt && 1722 (thflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK && 1723 tp->snd_nxt == tp->snd_max && 1724 tiwin && tiwin == tp->snd_wnd && 1725 ((tp->t_flags & (TF_NEEDSYN|TF_NEEDFIN)) == 0) && 1726 SEGQ_EMPTY(tp) && 1727 ((to.to_flags & TOF_TS) == 0 || 1728 TSTMP_GEQ(to.to_tsval, tp->ts_recent)) ) { 1729 /* 1730 * If last ACK falls within this segment's sequence numbers, 1731 * record the timestamp. 1732 * NOTE that the test is modified according to the latest 1733 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 1734 */ 1735 if ((to.to_flags & TOF_TS) != 0 && 1736 SEQ_LEQ(th->th_seq, tp->last_ack_sent)) { 1737 tp->ts_recent_age = tcp_ts_getticks(); 1738 tp->ts_recent = to.to_tsval; 1739 } 1740 1741 if (no_data) { 1742 if (SEQ_GT(th->th_ack, tp->snd_una) && 1743 SEQ_LEQ(th->th_ack, tp->snd_max) && 1744 !IN_RECOVERY(tp->t_flags) && 1745 (to.to_flags & TOF_SACK) == 0 && 1746 TAILQ_EMPTY(&tp->snd_holes)) { 1747 /* 1748 * This is a pure ack for outstanding data. 1749 */ 1750 TCPSTAT_INC(tcps_predack); 1751 1752 /* 1753 * "bad retransmit" recovery. 1754 */ 1755 if (tp->t_rxtshift == 1 && 1756 tp->t_flags & TF_PREVVALID && 1757 tp->t_badrxtwin != 0 && 1758 (((to.to_flags & TOF_TS) != 0 && 1759 to.to_tsecr != 0 && 1760 TSTMP_LT(to.to_tsecr, tp->t_badrxtwin)) || 1761 ((to.to_flags & TOF_TS) == 0 && 1762 TSTMP_LT(ticks, tp->t_badrxtwin)))) 1763 cc_cong_signal(tp, th, CC_RTO_ERR); 1764 1765 /* 1766 * Recalculate the transmit timer / rtt. 1767 * 1768 * Some boxes send broken timestamp replies 1769 * during the SYN+ACK phase, ignore 1770 * timestamps of 0 or we could calculate a 1771 * huge RTT and blow up the retransmit timer. 1772 */ 1773 if ((to.to_flags & TOF_TS) != 0 && 1774 to.to_tsecr) { 1775 uint32_t t; 1776 1777 t = tcp_ts_getticks() - to.to_tsecr; 1778 if (!tp->t_rttlow || tp->t_rttlow > t) 1779 tp->t_rttlow = t; 1780 tcp_xmit_timer(tp, 1781 TCP_TS_TO_TICKS(t) + 1); 1782 } else if (tp->t_rtttime && 1783 SEQ_GT(th->th_ack, tp->t_rtseq)) { 1784 if (!tp->t_rttlow || 1785 tp->t_rttlow > ticks - tp->t_rtttime) 1786 tp->t_rttlow = ticks - tp->t_rtttime; 1787 tcp_xmit_timer(tp, 1788 ticks - tp->t_rtttime); 1789 } 1790 acked = BYTES_THIS_ACK(tp, th); 1791 1792 #ifdef TCP_HHOOK 1793 /* Run HHOOK_TCP_ESTABLISHED_IN helper hooks. */ 1794 hhook_run_tcp_est_in(tp, th, &to); 1795 #endif 1796 1797 TCPSTAT_ADD(tcps_rcvackpack, nsegs); 1798 TCPSTAT_ADD(tcps_rcvackbyte, acked); 1799 sbdrop(&so->so_snd, acked); 1800 if (SEQ_GT(tp->snd_una, tp->snd_recover) && 1801 SEQ_LEQ(th->th_ack, tp->snd_recover)) 1802 tp->snd_recover = th->th_ack - 1; 1803 1804 /* 1805 * Let the congestion control algorithm update 1806 * congestion control related information. This 1807 * typically means increasing the congestion 1808 * window. 1809 */ 1810 cc_ack_received(tp, th, nsegs, CC_ACK); 1811 1812 tp->snd_una = th->th_ack; 1813 /* 1814 * Pull snd_wl2 up to prevent seq wrap relative 1815 * to th_ack. 1816 */ 1817 tp->snd_wl2 = th->th_ack; 1818 tp->t_dupacks = 0; 1819 m_freem(m); 1820 1821 /* 1822 * If all outstanding data are acked, stop 1823 * retransmit timer, otherwise restart timer 1824 * using current (possibly backed-off) value. 1825 * If process is waiting for space, 1826 * wakeup/selwakeup/signal. If data 1827 * are ready to send, let tcp_output 1828 * decide between more output or persist. 1829 */ 1830 TCP_PROBE3(debug__input, tp, th, m); 1831 /* 1832 * Clear t_acktime if remote side has ACKd 1833 * all data in the socket buffer. 1834 * Otherwise, update t_acktime if we received 1835 * a sufficiently large ACK. 1836 */ 1837 if (sbavail(&so->so_snd) == 0) 1838 tp->t_acktime = 0; 1839 else if (acked > 1) 1840 tp->t_acktime = ticks; 1841 if (tp->snd_una == tp->snd_max) 1842 tcp_timer_activate(tp, TT_REXMT, 0); 1843 else if (!tcp_timer_active(tp, TT_PERSIST)) 1844 tcp_timer_activate(tp, TT_REXMT, 1845 TP_RXTCUR(tp)); 1846 sowwakeup(so); 1847 /* 1848 * Only call tcp_output when there 1849 * is new data available to be sent 1850 * or we need to send an ACK. 1851 */ 1852 if ((tp->t_flags & TF_ACKNOW) || 1853 (sbavail(&so->so_snd) >= 1854 SEQ_SUB(tp->snd_max, tp->snd_una))) { 1855 (void) tcp_output(tp); 1856 } 1857 goto check_delack; 1858 } 1859 } else if (th->th_ack == tp->snd_una && 1860 tlen <= sbspace(&so->so_rcv)) { 1861 int newsize = 0; /* automatic sockbuf scaling */ 1862 1863 /* 1864 * This is a pure, in-sequence data packet with 1865 * nothing on the reassembly queue and we have enough 1866 * buffer space to take it. 1867 */ 1868 /* Clean receiver SACK report if present */ 1869 if ((tp->t_flags & TF_SACK_PERMIT) && tp->rcv_numsacks) 1870 tcp_clean_sackreport(tp); 1871 TCPSTAT_INC(tcps_preddat); 1872 tp->rcv_nxt += tlen; 1873 if (tlen && 1874 ((tp->t_flags2 & TF2_FBYTES_COMPLETE) == 0) && 1875 (tp->t_fbyte_in == 0)) { 1876 tp->t_fbyte_in = ticks; 1877 if (tp->t_fbyte_in == 0) 1878 tp->t_fbyte_in = 1; 1879 if (tp->t_fbyte_out && tp->t_fbyte_in) 1880 tp->t_flags2 |= TF2_FBYTES_COMPLETE; 1881 } 1882 /* 1883 * Pull snd_wl1 up to prevent seq wrap relative to 1884 * th_seq. 1885 */ 1886 tp->snd_wl1 = th->th_seq; 1887 /* 1888 * Pull rcv_up up to prevent seq wrap relative to 1889 * rcv_nxt. 1890 */ 1891 tp->rcv_up = tp->rcv_nxt; 1892 TCPSTAT_ADD(tcps_rcvpack, nsegs); 1893 TCPSTAT_ADD(tcps_rcvbyte, tlen); 1894 TCP_PROBE3(debug__input, tp, th, m); 1895 1896 newsize = tcp_autorcvbuf(m, th, so, tp, tlen); 1897 1898 /* Add data to socket buffer. */ 1899 SOCK_RECVBUF_LOCK(so); 1900 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 1901 m_freem(m); 1902 } else { 1903 /* 1904 * Set new socket buffer size. 1905 * Give up when limit is reached. 1906 */ 1907 if (newsize) 1908 if (!sbreserve_locked(so, SO_RCV, 1909 newsize, NULL)) 1910 so->so_rcv.sb_flags &= ~SB_AUTOSIZE; 1911 m_adj(m, drop_hdrlen); /* delayed header drop */ 1912 sbappendstream_locked(&so->so_rcv, m, 0); 1913 } 1914 /* NB: sorwakeup_locked() does an implicit unlock. */ 1915 sorwakeup_locked(so); 1916 if (DELAY_ACK(tp, tlen)) { 1917 tp->t_flags |= TF_DELACK; 1918 } else { 1919 tp->t_flags |= TF_ACKNOW; 1920 (void) tcp_output(tp); 1921 } 1922 goto check_delack; 1923 } 1924 } 1925 1926 /* 1927 * Calculate amount of space in receive window, 1928 * and then do TCP input processing. 1929 * Receive window is amount of space in rcv queue, 1930 * but not less than advertised window. 1931 */ 1932 win = sbspace(&so->so_rcv); 1933 if (win < 0) 1934 win = 0; 1935 tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt)); 1936 1937 switch (tp->t_state) { 1938 /* 1939 * If the state is SYN_RECEIVED: 1940 * if seg contains an ACK, but not for our SYN/ACK, send a RST. 1941 */ 1942 case TCPS_SYN_RECEIVED: 1943 if (thflags & TH_RST) { 1944 /* Handle RST segments later. */ 1945 break; 1946 } 1947 if ((thflags & TH_ACK) && 1948 (SEQ_LEQ(th->th_ack, tp->snd_una) || 1949 SEQ_GT(th->th_ack, tp->snd_max))) { 1950 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 1951 goto dropwithreset; 1952 } 1953 if (tp->t_flags & TF_FASTOPEN) { 1954 /* 1955 * When a TFO connection is in SYN_RECEIVED, the 1956 * only valid packets are the initial SYN, a 1957 * retransmit/copy of the initial SYN (possibly with 1958 * a subset of the original data), a valid ACK, a 1959 * FIN, or a RST. 1960 */ 1961 if ((thflags & (TH_SYN|TH_ACK)) == (TH_SYN|TH_ACK)) { 1962 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 1963 goto dropwithreset; 1964 } else if (thflags & TH_SYN) { 1965 /* non-initial SYN is ignored */ 1966 if ((tcp_timer_active(tp, TT_DELACK) || 1967 tcp_timer_active(tp, TT_REXMT))) 1968 goto drop; 1969 } else if (!(thflags & (TH_ACK|TH_FIN|TH_RST))) { 1970 goto drop; 1971 } 1972 } 1973 break; 1974 1975 /* 1976 * If the state is SYN_SENT: 1977 * if seg contains a RST with valid ACK (SEQ.ACK has already 1978 * been verified), then drop the connection. 1979 * if seg contains a RST without an ACK, drop the seg. 1980 * if seg does not contain SYN, then drop the seg. 1981 * Otherwise this is an acceptable SYN segment 1982 * initialize tp->rcv_nxt and tp->irs 1983 * if seg contains ack then advance tp->snd_una 1984 * if seg contains an ECE and ECN support is enabled, the stream 1985 * is ECN capable. 1986 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state 1987 * arrange for segment to be acked (eventually) 1988 * continue processing rest of data/controls, beginning with URG 1989 */ 1990 case TCPS_SYN_SENT: 1991 if ((thflags & (TH_ACK|TH_RST)) == (TH_ACK|TH_RST)) { 1992 TCP_PROBE5(connect__refused, NULL, tp, 1993 m, tp, th); 1994 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 1995 tp = tcp_drop(tp, ECONNREFUSED); 1996 } 1997 if (thflags & TH_RST) 1998 goto drop; 1999 if (!(thflags & TH_SYN)) 2000 goto drop; 2001 2002 tp->irs = th->th_seq; 2003 tcp_rcvseqinit(tp); 2004 if (thflags & TH_ACK) { 2005 int tfo_partial_ack = 0; 2006 2007 TCPSTAT_INC(tcps_connects); 2008 soisconnected(so); 2009 #ifdef MAC 2010 mac_socketpeer_set_from_mbuf(m, so); 2011 #endif 2012 /* Do window scaling on this connection? */ 2013 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2014 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2015 tp->rcv_scale = tp->request_r_scale; 2016 } 2017 tp->rcv_adv += min(tp->rcv_wnd, 2018 TCP_MAXWIN << tp->rcv_scale); 2019 tp->snd_una++; /* SYN is acked */ 2020 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2021 tp->snd_nxt = tp->snd_una; 2022 /* 2023 * If not all the data that was sent in the TFO SYN 2024 * has been acked, resend the remainder right away. 2025 */ 2026 if ((tp->t_flags & TF_FASTOPEN) && 2027 (tp->snd_una != tp->snd_max)) { 2028 tp->snd_nxt = th->th_ack; 2029 tfo_partial_ack = 1; 2030 } 2031 /* 2032 * If there's data, delay ACK; if there's also a FIN 2033 * ACKNOW will be turned on later. 2034 */ 2035 if (DELAY_ACK(tp, tlen) && tlen != 0 && !tfo_partial_ack) 2036 tcp_timer_activate(tp, TT_DELACK, 2037 tcp_delacktime); 2038 else 2039 tp->t_flags |= TF_ACKNOW; 2040 2041 tcp_ecn_input_syn_sent(tp, thflags, iptos); 2042 2043 /* 2044 * Received <SYN,ACK> in SYN_SENT[*] state. 2045 * Transitions: 2046 * SYN_SENT --> ESTABLISHED 2047 * SYN_SENT* --> FIN_WAIT_1 2048 */ 2049 tp->t_starttime = ticks; 2050 if (tp->t_flags & TF_NEEDFIN) { 2051 tp->t_acktime = ticks; 2052 tcp_state_change(tp, TCPS_FIN_WAIT_1); 2053 tp->t_flags &= ~TF_NEEDFIN; 2054 thflags &= ~TH_SYN; 2055 } else { 2056 tcp_state_change(tp, TCPS_ESTABLISHED); 2057 TCP_PROBE5(connect__established, NULL, tp, 2058 m, tp, th); 2059 cc_conn_init(tp); 2060 tcp_timer_activate(tp, TT_KEEP, 2061 TP_KEEPIDLE(tp)); 2062 } 2063 } else { 2064 /* 2065 * Received initial SYN in SYN-SENT[*] state => 2066 * simultaneous open. 2067 * If it succeeds, connection is * half-synchronized. 2068 * Otherwise, do 3-way handshake: 2069 * SYN-SENT -> SYN-RECEIVED 2070 * SYN-SENT* -> SYN-RECEIVED* 2071 */ 2072 tp->t_flags |= (TF_ACKNOW | TF_NEEDSYN | TF_SONOTCONN); 2073 tcp_timer_activate(tp, TT_REXMT, 0); 2074 tcp_state_change(tp, TCPS_SYN_RECEIVED); 2075 } 2076 2077 /* 2078 * Advance th->th_seq to correspond to first data byte. 2079 * If data, trim to stay within window, 2080 * dropping FIN if necessary. 2081 */ 2082 th->th_seq++; 2083 if (tlen > tp->rcv_wnd) { 2084 todrop = tlen - tp->rcv_wnd; 2085 m_adj(m, -todrop); 2086 tlen = tp->rcv_wnd; 2087 thflags &= ~TH_FIN; 2088 TCPSTAT_INC(tcps_rcvpackafterwin); 2089 TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); 2090 } 2091 tp->snd_wl1 = th->th_seq - 1; 2092 tp->rcv_up = th->th_seq; 2093 /* 2094 * Client side of transaction: already sent SYN and data. 2095 * If the remote host used T/TCP to validate the SYN, 2096 * our data will be ACK'd; if so, enter normal data segment 2097 * processing in the middle of step 5, ack processing. 2098 * Otherwise, goto step 6. 2099 */ 2100 if (thflags & TH_ACK) 2101 goto process_ACK; 2102 2103 goto step6; 2104 } 2105 2106 /* 2107 * States other than LISTEN or SYN_SENT. 2108 * First check the RST flag and sequence number since reset segments 2109 * are exempt from the timestamp and connection count tests. This 2110 * fixes a bug introduced by the Stevens, vol. 2, p. 960 bugfix 2111 * below which allowed reset segments in half the sequence space 2112 * to fall though and be processed (which gives forged reset 2113 * segments with a random sequence number a 50 percent chance of 2114 * killing a connection). 2115 * Then check timestamp, if present. 2116 * Then check the connection count, if present. 2117 * Then check that at least some bytes of segment are within 2118 * receive window. If segment begins before rcv_nxt, 2119 * drop leading data (and SYN); if nothing left, just ack. 2120 */ 2121 if (thflags & TH_RST) { 2122 /* 2123 * RFC5961 Section 3.2 2124 * 2125 * - RST drops connection only if SEG.SEQ == RCV.NXT. 2126 * - If RST is in window, we send challenge ACK. 2127 * 2128 * Note: to take into account delayed ACKs, we should 2129 * test against last_ack_sent instead of rcv_nxt. 2130 * Note 2: we handle special case of closed window, not 2131 * covered by the RFC. 2132 */ 2133 if ((SEQ_GEQ(th->th_seq, tp->last_ack_sent) && 2134 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) || 2135 (tp->rcv_wnd == 0 && tp->last_ack_sent == th->th_seq)) { 2136 KASSERT(tp->t_state != TCPS_SYN_SENT, 2137 ("%s: TH_RST for TCPS_SYN_SENT th %p tp %p", 2138 __func__, th, tp)); 2139 2140 if (V_tcp_insecure_rst || 2141 tp->last_ack_sent == th->th_seq) { 2142 TCPSTAT_INC(tcps_drops); 2143 /* Drop the connection. */ 2144 switch (tp->t_state) { 2145 case TCPS_SYN_RECEIVED: 2146 so->so_error = ECONNREFUSED; 2147 goto close; 2148 case TCPS_ESTABLISHED: 2149 case TCPS_FIN_WAIT_1: 2150 case TCPS_FIN_WAIT_2: 2151 case TCPS_CLOSE_WAIT: 2152 case TCPS_CLOSING: 2153 case TCPS_LAST_ACK: 2154 so->so_error = ECONNRESET; 2155 close: 2156 /* FALLTHROUGH */ 2157 default: 2158 tcp_log_end_status(tp, TCP_EI_STATUS_CLIENT_RST); 2159 tp = tcp_close(tp); 2160 } 2161 } else { 2162 TCPSTAT_INC(tcps_badrst); 2163 tcp_send_challenge_ack(tp, th, m); 2164 m = NULL; 2165 } 2166 } 2167 goto drop; 2168 } 2169 2170 /* 2171 * RFC5961 Section 4.2 2172 * Send challenge ACK for any SYN in synchronized state. 2173 */ 2174 if ((thflags & TH_SYN) && tp->t_state != TCPS_SYN_SENT && 2175 tp->t_state != TCPS_SYN_RECEIVED) { 2176 TCPSTAT_INC(tcps_badsyn); 2177 if (V_tcp_insecure_syn && 2178 SEQ_GEQ(th->th_seq, tp->last_ack_sent) && 2179 SEQ_LT(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) { 2180 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 2181 tp = tcp_drop(tp, ECONNRESET); 2182 } else { 2183 tcp_ecn_input_syn_sent(tp, thflags, iptos); 2184 tcp_send_challenge_ack(tp, th, m); 2185 m = NULL; 2186 } 2187 goto drop; 2188 } 2189 2190 /* 2191 * RFC 1323 PAWS: If we have a timestamp reply on this segment 2192 * and it's less than ts_recent, drop it. 2193 */ 2194 if ((to.to_flags & TOF_TS) != 0 && tp->ts_recent && 2195 TSTMP_LT(to.to_tsval, tp->ts_recent)) { 2196 /* Check to see if ts_recent is over 24 days old. */ 2197 if (tcp_ts_getticks() - tp->ts_recent_age > TCP_PAWS_IDLE) { 2198 /* 2199 * Invalidate ts_recent. If this segment updates 2200 * ts_recent, the age will be reset later and ts_recent 2201 * will get a valid value. If it does not, setting 2202 * ts_recent to zero will at least satisfy the 2203 * requirement that zero be placed in the timestamp 2204 * echo reply when ts_recent isn't valid. The 2205 * age isn't reset until we get a valid ts_recent 2206 * because we don't want out-of-order segments to be 2207 * dropped when ts_recent is old. 2208 */ 2209 tp->ts_recent = 0; 2210 } else { 2211 TCPSTAT_INC(tcps_rcvduppack); 2212 TCPSTAT_ADD(tcps_rcvdupbyte, tlen); 2213 TCPSTAT_INC(tcps_pawsdrop); 2214 if (tlen) 2215 goto dropafterack; 2216 goto drop; 2217 } 2218 } 2219 2220 /* 2221 * In the SYN-RECEIVED state, validate that the packet belongs to 2222 * this connection before trimming the data to fit the receive 2223 * window. Check the sequence number versus IRS since we know 2224 * the sequence numbers haven't wrapped. This is a partial fix 2225 * for the "LAND" DoS attack. 2226 */ 2227 if (tp->t_state == TCPS_SYN_RECEIVED && SEQ_LT(th->th_seq, tp->irs)) { 2228 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 2229 goto dropwithreset; 2230 } 2231 2232 todrop = tp->rcv_nxt - th->th_seq; 2233 if (todrop > 0) { 2234 if (thflags & TH_SYN) { 2235 thflags &= ~TH_SYN; 2236 th->th_seq++; 2237 if (th->th_urp > 1) 2238 th->th_urp--; 2239 else 2240 thflags &= ~TH_URG; 2241 todrop--; 2242 } 2243 /* 2244 * Following if statement from Stevens, vol. 2, p. 960. 2245 */ 2246 if (todrop > tlen 2247 || (todrop == tlen && (thflags & TH_FIN) == 0)) { 2248 /* 2249 * Any valid FIN must be to the left of the window. 2250 * At this point the FIN must be a duplicate or out 2251 * of sequence; drop it. 2252 */ 2253 thflags &= ~TH_FIN; 2254 2255 /* 2256 * Send an ACK to resynchronize and drop any data. 2257 * But keep on processing for RST or ACK. 2258 */ 2259 tp->t_flags |= TF_ACKNOW; 2260 todrop = tlen; 2261 TCPSTAT_INC(tcps_rcvduppack); 2262 TCPSTAT_ADD(tcps_rcvdupbyte, todrop); 2263 } else { 2264 TCPSTAT_INC(tcps_rcvpartduppack); 2265 TCPSTAT_ADD(tcps_rcvpartdupbyte, todrop); 2266 } 2267 /* 2268 * DSACK - add SACK block for dropped range 2269 */ 2270 if ((todrop > 0) && (tp->t_flags & TF_SACK_PERMIT)) { 2271 tcp_update_sack_list(tp, th->th_seq, 2272 th->th_seq + todrop); 2273 /* 2274 * ACK now, as the next in-sequence segment 2275 * will clear the DSACK block again 2276 */ 2277 tp->t_flags |= TF_ACKNOW; 2278 } 2279 drop_hdrlen += todrop; /* drop from the top afterwards */ 2280 th->th_seq += todrop; 2281 tlen -= todrop; 2282 if (th->th_urp > todrop) 2283 th->th_urp -= todrop; 2284 else { 2285 thflags &= ~TH_URG; 2286 th->th_urp = 0; 2287 } 2288 } 2289 2290 /* 2291 * If new data are received on a connection after the 2292 * user processes are gone, then RST the other end if 2293 * no FIN has been processed. 2294 */ 2295 if ((tp->t_flags & TF_CLOSED) && tlen > 0 && 2296 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 2297 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 2298 log(LOG_DEBUG, "%s; %s: %s: Received %d bytes of data " 2299 "after socket was closed, " 2300 "sending RST and removing tcpcb\n", 2301 s, __func__, tcpstates[tp->t_state], tlen); 2302 free(s, M_TCPLOG); 2303 } 2304 tcp_log_end_status(tp, TCP_EI_STATUS_DATA_A_CLOSE); 2305 /* tcp_close will kill the inp pre-log the Reset */ 2306 tcp_log_end_status(tp, TCP_EI_STATUS_SERVER_RST); 2307 tp = tcp_close(tp); 2308 TCPSTAT_INC(tcps_rcvafterclose); 2309 goto dropwithreset; 2310 } 2311 2312 /* 2313 * If segment ends after window, drop trailing data 2314 * (and PUSH and FIN); if nothing left, just ACK. 2315 */ 2316 todrop = (th->th_seq + tlen) - (tp->rcv_nxt + tp->rcv_wnd); 2317 if (todrop > 0) { 2318 TCPSTAT_INC(tcps_rcvpackafterwin); 2319 if (todrop >= tlen) { 2320 TCPSTAT_ADD(tcps_rcvbyteafterwin, tlen); 2321 /* 2322 * If window is closed can only take segments at 2323 * window edge, and have to drop data and PUSH from 2324 * incoming segments. Continue processing, but 2325 * remember to ack. Otherwise, drop segment 2326 * and ack. 2327 */ 2328 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { 2329 tp->t_flags |= TF_ACKNOW; 2330 TCPSTAT_INC(tcps_rcvwinprobe); 2331 } else 2332 goto dropafterack; 2333 } else 2334 TCPSTAT_ADD(tcps_rcvbyteafterwin, todrop); 2335 m_adj(m, -todrop); 2336 tlen -= todrop; 2337 thflags &= ~(TH_PUSH|TH_FIN); 2338 } 2339 2340 /* 2341 * If last ACK falls within this segment's sequence numbers, 2342 * record its timestamp. 2343 * NOTE: 2344 * 1) That the test incorporates suggestions from the latest 2345 * proposal of the tcplw@cray.com list (Braden 1993/04/26). 2346 * 2) That updating only on newer timestamps interferes with 2347 * our earlier PAWS tests, so this check should be solely 2348 * predicated on the sequence space of this segment. 2349 * 3) That we modify the segment boundary check to be 2350 * Last.ACK.Sent <= SEG.SEQ + SEG.Len 2351 * instead of RFC1323's 2352 * Last.ACK.Sent < SEG.SEQ + SEG.Len, 2353 * This modified check allows us to overcome RFC1323's 2354 * limitations as described in Stevens TCP/IP Illustrated 2355 * Vol. 2 p.869. In such cases, we can still calculate the 2356 * RTT correctly when RCV.NXT == Last.ACK.Sent. 2357 */ 2358 if ((to.to_flags & TOF_TS) != 0 && 2359 SEQ_LEQ(th->th_seq, tp->last_ack_sent) && 2360 SEQ_LEQ(tp->last_ack_sent, th->th_seq + tlen + 2361 ((thflags & (TH_SYN|TH_FIN)) != 0))) { 2362 tp->ts_recent_age = tcp_ts_getticks(); 2363 tp->ts_recent = to.to_tsval; 2364 } 2365 2366 /* 2367 * If the ACK bit is off: if in SYN-RECEIVED state or SENDSYN 2368 * flag is on (half-synchronized state), then queue data for 2369 * later processing; else drop segment and return. 2370 */ 2371 if ((thflags & TH_ACK) == 0) { 2372 if (tp->t_state == TCPS_SYN_RECEIVED || 2373 (tp->t_flags & TF_NEEDSYN)) { 2374 if (tp->t_state == TCPS_SYN_RECEIVED && 2375 (tp->t_flags & TF_FASTOPEN)) { 2376 tp->snd_wnd = tiwin; 2377 cc_conn_init(tp); 2378 } 2379 goto step6; 2380 } else if (tp->t_flags & TF_ACKNOW) 2381 goto dropafterack; 2382 else 2383 goto drop; 2384 } 2385 2386 /* 2387 * Ack processing. 2388 */ 2389 if (SEQ_GT(tp->snd_una, tp->iss + (TCP_MAXWIN << tp->snd_scale))) { 2390 /* Checking SEG.ACK against ISS is definitely redundant. */ 2391 tp->t_flags2 |= TF2_NO_ISS_CHECK; 2392 } 2393 if (!V_tcp_insecure_ack) { 2394 tcp_seq seq_min; 2395 bool ghost_ack_check; 2396 2397 if (tp->t_flags2 & TF2_NO_ISS_CHECK) { 2398 /* Check for too old ACKs (RFC 5961, Section 5.2). */ 2399 seq_min = tp->snd_una - tp->max_sndwnd; 2400 ghost_ack_check = false; 2401 } else { 2402 if (SEQ_GT(tp->iss + 1, tp->snd_una - tp->max_sndwnd)) { 2403 /* Checking for ghost ACKs is stricter. */ 2404 seq_min = tp->iss + 1; 2405 ghost_ack_check = true; 2406 } else { 2407 /* 2408 * Checking for too old ACKs (RFC 5961, 2409 * Section 5.2) is stricter. 2410 */ 2411 seq_min = tp->snd_una - tp->max_sndwnd; 2412 ghost_ack_check = false; 2413 } 2414 } 2415 if (SEQ_LT(th->th_ack, seq_min)) { 2416 if (ghost_ack_check) 2417 TCPSTAT_INC(tcps_rcvghostack); 2418 else 2419 TCPSTAT_INC(tcps_rcvacktooold); 2420 tcp_send_challenge_ack(tp, th, m); 2421 m = NULL; 2422 goto drop; 2423 } 2424 } 2425 switch (tp->t_state) { 2426 /* 2427 * In SYN_RECEIVED state, the ack ACKs our SYN, so enter 2428 * ESTABLISHED state and continue processing. 2429 * The ACK was checked above. 2430 */ 2431 case TCPS_SYN_RECEIVED: 2432 2433 TCPSTAT_INC(tcps_connects); 2434 if (tp->t_flags & TF_SONOTCONN) { 2435 /* 2436 * Usually SYN_RECEIVED had been created from a LISTEN, 2437 * and solisten_enqueue() has already marked the socket 2438 * layer as connected. If it didn't, which can happen 2439 * only with an accept_filter(9), then the tp is marked 2440 * with TF_SONOTCONN. The other reason for this mark 2441 * to be set is a simultaneous open, a SYN_RECEIVED 2442 * that had been created from SYN_SENT. 2443 */ 2444 tp->t_flags &= ~TF_SONOTCONN; 2445 soisconnected(so); 2446 } 2447 /* Do window scaling? */ 2448 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2449 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2450 tp->rcv_scale = tp->request_r_scale; 2451 } 2452 tp->snd_wnd = tiwin; 2453 /* 2454 * Make transitions: 2455 * SYN-RECEIVED -> ESTABLISHED 2456 * SYN-RECEIVED* -> FIN-WAIT-1 2457 */ 2458 tp->t_starttime = ticks; 2459 if ((tp->t_flags & TF_FASTOPEN) && tp->t_tfo_pending) { 2460 tcp_fastopen_decrement_counter(tp->t_tfo_pending); 2461 tp->t_tfo_pending = NULL; 2462 } 2463 if (tp->t_flags & TF_NEEDFIN) { 2464 tp->t_acktime = ticks; 2465 tcp_state_change(tp, TCPS_FIN_WAIT_1); 2466 tp->t_flags &= ~TF_NEEDFIN; 2467 } else { 2468 tcp_state_change(tp, TCPS_ESTABLISHED); 2469 TCP_PROBE5(accept__established, NULL, tp, 2470 m, tp, th); 2471 /* 2472 * TFO connections call cc_conn_init() during SYN 2473 * processing. Calling it again here for such 2474 * connections is not harmless as it would undo the 2475 * snd_cwnd reduction that occurs when a TFO SYN|ACK 2476 * is retransmitted. 2477 */ 2478 if (!(tp->t_flags & TF_FASTOPEN)) 2479 cc_conn_init(tp); 2480 tcp_timer_activate(tp, TT_KEEP, TP_KEEPIDLE(tp)); 2481 } 2482 /* 2483 * Account for the ACK of our SYN prior to 2484 * regular ACK processing below, except for 2485 * simultaneous SYN, which is handled later. 2486 */ 2487 if (SEQ_GT(th->th_ack, tp->snd_una) && !(tp->t_flags & TF_NEEDSYN)) 2488 incforsyn = 1; 2489 /* 2490 * If segment contains data or ACK, will call tcp_reass() 2491 * later; if not, do so now to pass queued data to user. 2492 */ 2493 if (tlen == 0 && (thflags & TH_FIN) == 0) { 2494 (void) tcp_reass(tp, (struct tcphdr *)0, NULL, 0, 2495 (struct mbuf *)0); 2496 tcp_handle_wakeup(tp); 2497 } 2498 tp->snd_wl1 = th->th_seq - 1; 2499 /* FALLTHROUGH */ 2500 2501 /* 2502 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range 2503 * ACKs. If the ack is in the range 2504 * tp->snd_una < th->th_ack <= tp->snd_max 2505 * then advance tp->snd_una to th->th_ack and drop 2506 * data from the retransmission queue. If this ACK reflects 2507 * more up to date window information we update our window information. 2508 */ 2509 case TCPS_ESTABLISHED: 2510 case TCPS_FIN_WAIT_1: 2511 case TCPS_FIN_WAIT_2: 2512 case TCPS_CLOSE_WAIT: 2513 case TCPS_CLOSING: 2514 case TCPS_LAST_ACK: 2515 if (SEQ_GT(th->th_ack, tp->snd_max)) { 2516 TCPSTAT_INC(tcps_rcvacktoomuch); 2517 goto dropafterack; 2518 } 2519 if (tcp_is_sack_recovery(tp, &to)) { 2520 prev_sacked_bytes = tp->sackhint.sacked_bytes; 2521 sack_changed = tcp_sack_doack(tp, &to, th->th_ack); 2522 if ((sack_changed != SACK_NOCHANGE) && 2523 (tp->t_flags & TF_LRD)) { 2524 tcp_sack_lost_retransmission(tp, th); 2525 } 2526 } else 2527 /* 2528 * Reset the value so that previous (valid) value 2529 * from the last ack with SACK doesn't get used. 2530 */ 2531 tp->sackhint.sacked_bytes = 0; 2532 2533 #ifdef TCP_HHOOK 2534 /* Run HHOOK_TCP_ESTABLISHED_IN helper hooks. */ 2535 hhook_run_tcp_est_in(tp, th, &to); 2536 #endif 2537 2538 if (SEQ_LT(th->th_ack, tp->snd_una)) { 2539 /* This is old ACK information, don't process it. */ 2540 break; 2541 } 2542 if (th->th_ack == tp->snd_una) { 2543 /* Check if this is a duplicate ACK. */ 2544 if (tp->t_flags & TF_SACK_PERMIT) { 2545 /* 2546 * If SEG.ACK == SND.UNA, RFC 6675 requires a 2547 * duplicate ACK to selectively acknowledge 2548 * at least one byte, which was not selectively 2549 * acknowledged before. 2550 */ 2551 if (sack_changed == SACK_NOCHANGE) { 2552 break; 2553 } 2554 } else { 2555 /* 2556 * If SEG.ACK == SND.UNA, RFC 5681 requires a 2557 * duplicate ACK to have no data on it and to 2558 * not be a window update. 2559 */ 2560 if (!no_data || tiwin != tp->snd_wnd) { 2561 break; 2562 } 2563 } 2564 /* 2565 * If this is the first time we've seen a 2566 * FIN from the remote, this is not a 2567 * duplicate ACK and it needs to be processed 2568 * normally. 2569 * This happens during a simultaneous close. 2570 */ 2571 if ((thflags & TH_FIN) && 2572 (TCPS_HAVERCVDFIN(tp->t_state) == 0)) { 2573 tp->t_dupacks = 0; 2574 break; 2575 } 2576 /* Perform duplicate ACK processing. */ 2577 TCPSTAT_INC(tcps_rcvdupack); 2578 maxseg = tcp_maxseg(tp); 2579 if (!tcp_timer_active(tp, TT_REXMT)) { 2580 tp->t_dupacks = 0; 2581 } else if (++tp->t_dupacks > tcprexmtthresh || 2582 IN_FASTRECOVERY(tp->t_flags)) { 2583 cc_ack_received(tp, th, nsegs, CC_DUPACK); 2584 if (V_tcp_do_prr && 2585 IN_FASTRECOVERY(tp->t_flags) && 2586 (tp->t_flags & TF_SACK_PERMIT)) { 2587 tcp_do_prr_ack(tp, th, &to, 2588 sack_changed, &maxseg); 2589 } else if (tcp_is_sack_recovery(tp, &to) && 2590 IN_FASTRECOVERY(tp->t_flags) && 2591 (tp->snd_nxt == tp->snd_max)) { 2592 int awnd; 2593 2594 /* 2595 * Compute the amount of data in flight first. 2596 * We can inject new data into the pipe iff 2597 * we have less than ssthresh 2598 * worth of data in flight. 2599 */ 2600 awnd = tcp_compute_pipe(tp); 2601 if (awnd < tp->snd_ssthresh) { 2602 tp->snd_cwnd += imax(maxseg, 2603 imin(2 * maxseg, 2604 tp->sackhint.delivered_data)); 2605 if (tp->snd_cwnd > tp->snd_ssthresh) 2606 tp->snd_cwnd = tp->snd_ssthresh; 2607 } 2608 } else if (tcp_is_sack_recovery(tp, &to) && 2609 IN_FASTRECOVERY(tp->t_flags) && 2610 SEQ_LT(tp->snd_nxt, tp->snd_max)) { 2611 tp->snd_cwnd += imax(maxseg, 2612 imin(2 * maxseg, 2613 tp->sackhint.delivered_data)); 2614 } else { 2615 tp->snd_cwnd += maxseg; 2616 } 2617 (void) tcp_output(tp); 2618 goto drop; 2619 } else if (tp->t_dupacks == tcprexmtthresh || 2620 (tp->t_flags & TF_SACK_PERMIT && 2621 tp->sackhint.sacked_bytes > 2622 (tcprexmtthresh - 1) * maxseg)) { 2623 enter_recovery: 2624 /* 2625 * Above is the RFC6675 trigger condition of 2626 * more than (dupthresh-1)*maxseg sacked data. 2627 * If the count of holes in the 2628 * scoreboard is >= dupthresh, we could 2629 * also enter loss recovery, but don't 2630 * have that value readily available. 2631 */ 2632 tp->t_dupacks = tcprexmtthresh; 2633 tcp_seq onxt = tp->snd_nxt; 2634 2635 /* 2636 * If we're doing sack, check to 2637 * see if we're already in sack 2638 * recovery. If we're not doing sack, 2639 * check to see if we're in newreno 2640 * recovery. 2641 */ 2642 if (tcp_is_sack_recovery(tp, &to)) { 2643 if (IN_FASTRECOVERY(tp->t_flags)) { 2644 tp->t_dupacks = 0; 2645 break; 2646 } 2647 } else { 2648 if (SEQ_LEQ(th->th_ack, 2649 tp->snd_recover)) { 2650 tp->t_dupacks = 0; 2651 break; 2652 } 2653 } 2654 /* Congestion signal before ack. */ 2655 cc_cong_signal(tp, th, CC_NDUPACK); 2656 cc_ack_received(tp, th, nsegs, CC_DUPACK); 2657 tcp_timer_activate(tp, TT_REXMT, 0); 2658 tp->t_rtttime = 0; 2659 if (V_tcp_do_prr) { 2660 /* 2661 * snd_ssthresh and snd_recover are 2662 * already updated by cc_cong_signal. 2663 */ 2664 if (tcp_is_sack_recovery(tp, &to)) { 2665 /* 2666 * Include Limited Transmit 2667 * segments here 2668 */ 2669 tp->sackhint.prr_delivered = 2670 imin(tp->snd_max - th->th_ack, 2671 (tp->snd_limited + 1) * maxseg); 2672 tp->sackhint.recover_fs = imax(1, 2673 (tp->snd_nxt - tp->snd_una) - prev_sacked_bytes 2674 + tp->sackhint.delivered_data); 2675 } else { 2676 tp->sackhint.prr_delivered = 2677 maxseg; 2678 tp->sackhint.recover_fs = max(1, 2679 tp->snd_nxt - tp->snd_una); 2680 } 2681 } 2682 tp->snd_limited = 0; 2683 if (tcp_is_sack_recovery(tp, &to)) { 2684 TCPSTAT_INC(tcps_sack_recovery_episode); 2685 /* 2686 * When entering LR after RTO due to 2687 * Duplicate ACKs, retransmit existing 2688 * holes from the scoreboard. 2689 */ 2690 tcp_resend_sackholes(tp); 2691 /* Avoid inflating cwnd in tcp_output */ 2692 tp->snd_nxt = tp->snd_max; 2693 tp->snd_cwnd = tcp_compute_pipe(tp) + 2694 maxseg; 2695 (void) tcp_output(tp); 2696 /* Set cwnd to the expected flightsize */ 2697 tp->snd_cwnd = tp->snd_ssthresh; 2698 goto drop; 2699 } 2700 tp->snd_nxt = th->th_ack; 2701 tp->snd_cwnd = maxseg; 2702 (void) tcp_output(tp); 2703 KASSERT(tp->snd_limited <= 2, 2704 ("%s: tp->snd_limited too big", 2705 __func__)); 2706 tp->snd_cwnd = tp->snd_ssthresh + 2707 maxseg * 2708 (tp->t_dupacks - tp->snd_limited); 2709 if (SEQ_GT(onxt, tp->snd_nxt)) 2710 tp->snd_nxt = onxt; 2711 goto drop; 2712 } else if (V_tcp_do_rfc3042) { 2713 /* 2714 * Process first and second duplicate 2715 * ACKs. Each indicates a segment 2716 * leaving the network, creating room 2717 * for more. Make sure we can send a 2718 * packet on reception of each duplicate 2719 * ACK by increasing snd_cwnd by one 2720 * segment. Restore the original 2721 * snd_cwnd after packet transmission. 2722 */ 2723 cc_ack_received(tp, th, nsegs, CC_DUPACK); 2724 uint32_t oldcwnd = tp->snd_cwnd; 2725 tcp_seq oldsndmax = tp->snd_max; 2726 u_int sent; 2727 int avail; 2728 2729 KASSERT(tp->t_dupacks == 1 || 2730 tp->t_dupacks == 2, 2731 ("%s: dupacks not 1 or 2", 2732 __func__)); 2733 if (tp->t_dupacks == 1) 2734 tp->snd_limited = 0; 2735 if ((tp->snd_nxt == tp->snd_max) && 2736 (tp->t_rxtshift == 0)) 2737 tp->snd_cwnd = 2738 SEQ_SUB(tp->snd_nxt, tp->snd_una); 2739 tp->snd_cwnd += 2740 (tp->t_dupacks - tp->snd_limited) * maxseg; 2741 tp->snd_cwnd -= tcp_sack_adjust(tp); 2742 /* 2743 * Only call tcp_output when there 2744 * is new data available to be sent 2745 * or we need to send an ACK. 2746 */ 2747 SOCK_SENDBUF_LOCK(so); 2748 avail = sbavail(&so->so_snd); 2749 SOCK_SENDBUF_UNLOCK(so); 2750 if (tp->t_flags & TF_ACKNOW || 2751 (avail >= 2752 SEQ_SUB(tp->snd_nxt, tp->snd_una))) { 2753 (void) tcp_output(tp); 2754 } 2755 sent = SEQ_SUB(tp->snd_max, oldsndmax); 2756 if (sent > maxseg) { 2757 KASSERT((tp->t_dupacks == 2 && 2758 tp->snd_limited == 0) || 2759 (sent == maxseg + 1 && 2760 tp->t_flags & TF_SENTFIN) || 2761 (sent < 2 * maxseg && 2762 tp->t_flags & TF_NODELAY), 2763 ("%s: sent too much: %u>%u", 2764 __func__, sent, maxseg)); 2765 tp->snd_limited = 2; 2766 } else if (sent > 0) { 2767 ++tp->snd_limited; 2768 } 2769 tp->snd_cwnd = oldcwnd; 2770 goto drop; 2771 } 2772 break; 2773 } 2774 KASSERT(SEQ_GT(th->th_ack, tp->snd_una), 2775 ("%s: SEQ_LEQ(th_ack, snd_una)", __func__)); 2776 /* 2777 * This ack is advancing the left edge, reset the 2778 * counter. 2779 */ 2780 tp->t_dupacks = 0; 2781 /* 2782 * If this ack also has new SACK info, increment the 2783 * t_dupacks as per RFC 6675. The variable 2784 * sack_changed tracks all changes to the SACK 2785 * scoreboard, including when partial ACKs without 2786 * SACK options are received, and clear the scoreboard 2787 * from the left side. Such partial ACKs should not be 2788 * counted as dupacks here. 2789 */ 2790 if (tcp_is_sack_recovery(tp, &to) && 2791 (((tp->t_rxtshift == 0) && (sack_changed != SACK_NOCHANGE)) || 2792 ((tp->t_rxtshift > 0) && (sack_changed == SACK_NEWLOSS))) && 2793 (tp->snd_nxt == tp->snd_max)) { 2794 tp->t_dupacks++; 2795 /* limit overhead by setting maxseg last */ 2796 if (!IN_FASTRECOVERY(tp->t_flags) && 2797 (tp->sackhint.sacked_bytes > 2798 (tcprexmtthresh - 1) * (maxseg = tcp_maxseg(tp)))) { 2799 goto enter_recovery; 2800 } 2801 } 2802 /* 2803 * If the congestion window was inflated to account 2804 * for the other side's cached packets, retract it. 2805 */ 2806 if (SEQ_LT(th->th_ack, tp->snd_recover)) { 2807 if (IN_FASTRECOVERY(tp->t_flags)) { 2808 if (tp->t_flags & TF_SACK_PERMIT) { 2809 if (V_tcp_do_prr && 2810 (to.to_flags & TOF_SACK)) { 2811 tcp_timer_activate(tp, 2812 TT_REXMT, 0); 2813 tp->t_rtttime = 0; 2814 tcp_do_prr_ack(tp, th, &to, 2815 sack_changed, &maxseg); 2816 tp->t_flags |= TF_ACKNOW; 2817 (void) tcp_output(tp); 2818 } else { 2819 tcp_sack_partialack(tp, th, 2820 &maxseg); 2821 } 2822 } else { 2823 tcp_newreno_partial_ack(tp, th); 2824 } 2825 } else if (IN_CONGRECOVERY(tp->t_flags) && 2826 (V_tcp_do_prr)) { 2827 tp->sackhint.delivered_data = 2828 BYTES_THIS_ACK(tp, th); 2829 tp->snd_fack = th->th_ack; 2830 /* 2831 * During ECN cwnd reduction 2832 * always use PRR-SSRB 2833 */ 2834 tcp_do_prr_ack(tp, th, &to, SACK_CHANGE, 2835 &maxseg); 2836 (void) tcp_output(tp); 2837 } 2838 } 2839 /* 2840 * If we reach this point, ACK is not a duplicate, 2841 * i.e., it ACKs something we sent. 2842 */ 2843 if (tp->t_flags & TF_NEEDSYN) { 2844 /* 2845 * T/TCP: Connection was half-synchronized, and our 2846 * SYN has been ACK'd (so connection is now fully 2847 * synchronized). Go to non-starred state, 2848 * increment snd_una for ACK of SYN, and check if 2849 * we can do window scaling. 2850 */ 2851 tp->t_flags &= ~TF_NEEDSYN; 2852 tp->snd_una++; 2853 /* Do window scaling? */ 2854 if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) == 2855 (TF_RCVD_SCALE|TF_REQ_SCALE)) { 2856 tp->rcv_scale = tp->request_r_scale; 2857 /* Send window already scaled. */ 2858 } 2859 } 2860 2861 process_ACK: 2862 INP_WLOCK_ASSERT(inp); 2863 2864 /* 2865 * Adjust for the SYN bit in sequence space, 2866 * but don't account for it in cwnd calculations. 2867 * This is for the SYN_RECEIVED, non-simultaneous 2868 * SYN case. SYN_SENT and simultaneous SYN are 2869 * treated elsewhere. 2870 */ 2871 if (incforsyn) 2872 tp->snd_una++; 2873 acked = BYTES_THIS_ACK(tp, th); 2874 KASSERT(acked >= 0, ("%s: acked unexepectedly negative " 2875 "(tp->snd_una=%u, th->th_ack=%u, tp=%p, m=%p)", __func__, 2876 tp->snd_una, th->th_ack, tp, m)); 2877 TCPSTAT_ADD(tcps_rcvackpack, nsegs); 2878 TCPSTAT_ADD(tcps_rcvackbyte, acked); 2879 2880 /* 2881 * If we just performed our first retransmit, and the ACK 2882 * arrives within our recovery window, then it was a mistake 2883 * to do the retransmit in the first place. Recover our 2884 * original cwnd and ssthresh, and proceed to transmit where 2885 * we left off. 2886 */ 2887 if (tp->t_rxtshift == 1 && 2888 tp->t_flags & TF_PREVVALID && 2889 tp->t_badrxtwin != 0 && 2890 to.to_flags & TOF_TS && 2891 to.to_tsecr != 0 && 2892 TSTMP_LT(to.to_tsecr, tp->t_badrxtwin)) 2893 cc_cong_signal(tp, th, CC_RTO_ERR); 2894 2895 /* 2896 * If we have a timestamp reply, update smoothed 2897 * round trip time. If no timestamp is present but 2898 * transmit timer is running and timed sequence 2899 * number was acked, update smoothed round trip time. 2900 * Since we now have an rtt measurement, cancel the 2901 * timer backoff (cf., Phil Karn's retransmit alg.). 2902 * Recompute the initial retransmit timer. 2903 * 2904 * Some boxes send broken timestamp replies 2905 * during the SYN+ACK phase, ignore 2906 * timestamps of 0 or we could calculate a 2907 * huge RTT and blow up the retransmit timer. 2908 */ 2909 if ((to.to_flags & TOF_TS) != 0 && to.to_tsecr) { 2910 uint32_t t; 2911 2912 t = tcp_ts_getticks() - to.to_tsecr; 2913 if (!tp->t_rttlow || tp->t_rttlow > t) 2914 tp->t_rttlow = t; 2915 tcp_xmit_timer(tp, TCP_TS_TO_TICKS(t) + 1); 2916 } else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) { 2917 if (!tp->t_rttlow || tp->t_rttlow > ticks - tp->t_rtttime) 2918 tp->t_rttlow = ticks - tp->t_rtttime; 2919 tcp_xmit_timer(tp, ticks - tp->t_rtttime); 2920 } 2921 2922 SOCK_SENDBUF_LOCK(so); 2923 /* 2924 * Clear t_acktime if remote side has ACKd all data in the 2925 * socket buffer and FIN (if applicable). 2926 * Otherwise, update t_acktime if we received a sufficiently 2927 * large ACK. 2928 */ 2929 if ((tp->t_state <= TCPS_CLOSE_WAIT && 2930 acked == sbavail(&so->so_snd)) || 2931 acked > sbavail(&so->so_snd)) 2932 tp->t_acktime = 0; 2933 else if (acked > 1) 2934 tp->t_acktime = ticks; 2935 2936 /* 2937 * If all outstanding data is acked, stop retransmit 2938 * timer and remember to restart (more output or persist). 2939 * If there is more data to be acked, restart retransmit 2940 * timer, using current (possibly backed-off) value. 2941 */ 2942 if (th->th_ack == tp->snd_max) { 2943 tcp_timer_activate(tp, TT_REXMT, 0); 2944 needoutput = 1; 2945 } else if (!tcp_timer_active(tp, TT_PERSIST)) 2946 tcp_timer_activate(tp, TT_REXMT, TP_RXTCUR(tp)); 2947 2948 /* 2949 * If no data (only SYN) was ACK'd, 2950 * skip rest of ACK processing. 2951 */ 2952 if (acked == 0) { 2953 SOCK_SENDBUF_UNLOCK(so); 2954 goto step6; 2955 } 2956 2957 /* 2958 * Let the congestion control algorithm update congestion 2959 * control related information. This typically means increasing 2960 * the congestion window. 2961 */ 2962 cc_ack_received(tp, th, nsegs, CC_ACK); 2963 2964 if (acked > sbavail(&so->so_snd)) { 2965 if (tp->snd_wnd >= sbavail(&so->so_snd)) 2966 tp->snd_wnd -= sbavail(&so->so_snd); 2967 else 2968 tp->snd_wnd = 0; 2969 mfree = sbcut_locked(&so->so_snd, 2970 (int)sbavail(&so->so_snd)); 2971 ourfinisacked = 1; 2972 } else { 2973 mfree = sbcut_locked(&so->so_snd, acked); 2974 if (tp->snd_wnd >= (uint32_t) acked) 2975 tp->snd_wnd -= acked; 2976 else 2977 tp->snd_wnd = 0; 2978 ourfinisacked = 0; 2979 } 2980 /* NB: sowwakeup_locked() does an implicit unlock. */ 2981 sowwakeup_locked(so); 2982 m_freem(mfree); 2983 /* Detect una wraparound. */ 2984 if (!IN_RECOVERY(tp->t_flags) && 2985 SEQ_GT(tp->snd_una, tp->snd_recover) && 2986 SEQ_LEQ(th->th_ack, tp->snd_recover)) 2987 tp->snd_recover = th->th_ack - 1; 2988 tp->snd_una = th->th_ack; 2989 if (IN_RECOVERY(tp->t_flags) && 2990 SEQ_GEQ(th->th_ack, tp->snd_recover)) { 2991 cc_post_recovery(tp, th); 2992 } 2993 if (SEQ_GT(tp->snd_una, tp->snd_recover)) { 2994 tp->snd_recover = tp->snd_una; 2995 } 2996 if (SEQ_LT(tp->snd_nxt, tp->snd_una)) 2997 tp->snd_nxt = tp->snd_una; 2998 2999 switch (tp->t_state) { 3000 /* 3001 * In FIN_WAIT_1 STATE in addition to the processing 3002 * for the ESTABLISHED state if our FIN is now acknowledged 3003 * then enter FIN_WAIT_2. 3004 */ 3005 case TCPS_FIN_WAIT_1: 3006 if (ourfinisacked) { 3007 /* 3008 * If we can't receive any more 3009 * data, then closing user can proceed. 3010 * Starting the timer is contrary to the 3011 * specification, but if we don't get a FIN 3012 * we'll hang forever. 3013 */ 3014 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) { 3015 tcp_free_sackholes(tp); 3016 soisdisconnected(so); 3017 tcp_timer_activate(tp, TT_2MSL, 3018 (tcp_fast_finwait2_recycle ? 3019 tcp_finwait2_timeout : 3020 TP_MAXIDLE(tp))); 3021 } 3022 tcp_state_change(tp, TCPS_FIN_WAIT_2); 3023 } 3024 break; 3025 3026 /* 3027 * In CLOSING STATE in addition to the processing for 3028 * the ESTABLISHED state if the ACK acknowledges our FIN 3029 * then enter the TIME-WAIT state, otherwise ignore 3030 * the segment. 3031 */ 3032 case TCPS_CLOSING: 3033 if (ourfinisacked) { 3034 tcp_twstart(tp); 3035 m_freem(m); 3036 return; 3037 } 3038 break; 3039 3040 /* 3041 * In LAST_ACK, we may still be waiting for data to drain 3042 * and/or to be acked, as well as for the ack of our FIN. 3043 * If our FIN is now acknowledged, delete the TCB, 3044 * enter the closed state and return. 3045 */ 3046 case TCPS_LAST_ACK: 3047 if (ourfinisacked) { 3048 tp = tcp_close(tp); 3049 goto drop; 3050 } 3051 break; 3052 } 3053 } 3054 3055 step6: 3056 INP_WLOCK_ASSERT(inp); 3057 3058 /* 3059 * Update window information. 3060 * Don't look at window if no ACK: TAC's send garbage on first SYN. 3061 */ 3062 if ((thflags & TH_ACK) && 3063 (SEQ_LT(tp->snd_wl1, th->th_seq) || 3064 (tp->snd_wl1 == th->th_seq && (SEQ_LT(tp->snd_wl2, th->th_ack) || 3065 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))) { 3066 /* keep track of pure window updates */ 3067 if (no_data && tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd) 3068 TCPSTAT_INC(tcps_rcvwinupd); 3069 tp->snd_wnd = tiwin; 3070 tp->snd_wl1 = th->th_seq; 3071 tp->snd_wl2 = th->th_ack; 3072 if (tp->snd_wnd > tp->max_sndwnd) 3073 tp->max_sndwnd = tp->snd_wnd; 3074 needoutput = 1; 3075 } 3076 3077 /* 3078 * Process segments with URG. 3079 */ 3080 if ((thflags & TH_URG) && th->th_urp && 3081 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3082 /* 3083 * This is a kludge, but if we receive and accept 3084 * random urgent pointers, we'll crash in 3085 * soreceive. It's hard to imagine someone 3086 * actually wanting to send this much urgent data. 3087 */ 3088 SOCK_RECVBUF_LOCK(so); 3089 if (th->th_urp + sbavail(&so->so_rcv) > sb_max) { 3090 th->th_urp = 0; /* XXX */ 3091 thflags &= ~TH_URG; /* XXX */ 3092 SOCK_RECVBUF_UNLOCK(so); /* XXX */ 3093 goto dodata; /* XXX */ 3094 } 3095 /* 3096 * If this segment advances the known urgent pointer, 3097 * then mark the data stream. This should not happen 3098 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since 3099 * a FIN has been received from the remote side. 3100 * In these states we ignore the URG. 3101 * 3102 * According to RFC961 (Assigned Protocols), 3103 * the urgent pointer points to the last octet 3104 * of urgent data. We continue, however, 3105 * to consider it to indicate the first octet 3106 * of data past the urgent section as the original 3107 * spec states (in one of two places). 3108 */ 3109 if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) { 3110 tp->rcv_up = th->th_seq + th->th_urp; 3111 so->so_oobmark = sbavail(&so->so_rcv) + 3112 (tp->rcv_up - tp->rcv_nxt) - 1; 3113 if (so->so_oobmark == 0) 3114 so->so_rcv.sb_state |= SBS_RCVATMARK; 3115 sohasoutofband(so); 3116 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); 3117 } 3118 SOCK_RECVBUF_UNLOCK(so); 3119 /* 3120 * Remove out of band data so doesn't get presented to user. 3121 * This can happen independent of advancing the URG pointer, 3122 * but if two URG's are pending at once, some out-of-band 3123 * data may creep in... ick. 3124 */ 3125 if (th->th_urp <= (uint32_t)tlen && 3126 !(so->so_options & SO_OOBINLINE)) { 3127 /* hdr drop is delayed */ 3128 tcp_pulloutofband(so, th, m, drop_hdrlen); 3129 } 3130 } else { 3131 /* 3132 * If no out of band data is expected, 3133 * pull receive urgent pointer along 3134 * with the receive window. 3135 */ 3136 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) 3137 tp->rcv_up = tp->rcv_nxt; 3138 } 3139 dodata: /* XXX */ 3140 INP_WLOCK_ASSERT(inp); 3141 3142 /* 3143 * Process the segment text, merging it into the TCP sequencing queue, 3144 * and arranging for acknowledgment of receipt if necessary. 3145 * This process logically involves adjusting tp->rcv_wnd as data 3146 * is presented to the user (this happens in tcp_usrreq.c, 3147 * case PRU_RCVD). If a FIN has already been received on this 3148 * connection then we just ignore the text. 3149 */ 3150 tfo_syn = ((tp->t_state == TCPS_SYN_RECEIVED) && 3151 (tp->t_flags & TF_FASTOPEN)); 3152 if ((tlen || (thflags & TH_FIN) || (tfo_syn && tlen > 0)) && 3153 TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3154 tcp_seq save_start = th->th_seq; 3155 tcp_seq save_rnxt = tp->rcv_nxt; 3156 int save_tlen = tlen; 3157 m_adj(m, drop_hdrlen); /* delayed header drop */ 3158 /* 3159 * Insert segment which includes th into TCP reassembly queue 3160 * with control block tp. Set thflags to whether reassembly now 3161 * includes a segment with FIN. This handles the common case 3162 * inline (segment is the next to be received on an established 3163 * connection, and the queue is empty), avoiding linkage into 3164 * and removal from the queue and repetition of various 3165 * conversions. 3166 * Set DELACK for segments received in order, but ack 3167 * immediately when segments are out of order (so 3168 * fast retransmit can work). 3169 */ 3170 if (th->th_seq == tp->rcv_nxt && 3171 SEGQ_EMPTY(tp) && 3172 (TCPS_HAVEESTABLISHED(tp->t_state) || 3173 tfo_syn)) { 3174 if (DELAY_ACK(tp, tlen) || tfo_syn) 3175 tp->t_flags |= TF_DELACK; 3176 else 3177 tp->t_flags |= TF_ACKNOW; 3178 tp->rcv_nxt += tlen; 3179 if (tlen && 3180 ((tp->t_flags2 & TF2_FBYTES_COMPLETE) == 0) && 3181 (tp->t_fbyte_in == 0)) { 3182 tp->t_fbyte_in = ticks; 3183 if (tp->t_fbyte_in == 0) 3184 tp->t_fbyte_in = 1; 3185 if (tp->t_fbyte_out && tp->t_fbyte_in) 3186 tp->t_flags2 |= TF2_FBYTES_COMPLETE; 3187 } 3188 thflags = tcp_get_flags(th) & TH_FIN; 3189 TCPSTAT_INC(tcps_rcvpack); 3190 TCPSTAT_ADD(tcps_rcvbyte, tlen); 3191 SOCK_RECVBUF_LOCK(so); 3192 if (so->so_rcv.sb_state & SBS_CANTRCVMORE) 3193 m_freem(m); 3194 else 3195 sbappendstream_locked(&so->so_rcv, m, 0); 3196 tp->t_flags |= TF_WAKESOR; 3197 } else { 3198 /* 3199 * XXX: Due to the header drop above "th" is 3200 * theoretically invalid by now. Fortunately 3201 * m_adj() doesn't actually frees any mbufs 3202 * when trimming from the head. 3203 */ 3204 tcp_seq temp = save_start; 3205 3206 thflags = tcp_reass(tp, th, &temp, &tlen, m); 3207 tp->t_flags |= TF_ACKNOW; 3208 } 3209 if ((tp->t_flags & TF_SACK_PERMIT) && 3210 (save_tlen > 0) && 3211 TCPS_HAVEESTABLISHED(tp->t_state)) { 3212 if ((tlen == 0) && (SEQ_LT(save_start, save_rnxt))) { 3213 /* 3214 * DSACK actually handled in the fastpath 3215 * above. 3216 */ 3217 tcp_update_sack_list(tp, save_start, 3218 save_start + save_tlen); 3219 } else if ((tlen > 0) && SEQ_GT(tp->rcv_nxt, save_rnxt)) { 3220 if ((tp->rcv_numsacks >= 1) && 3221 (tp->sackblks[0].end == save_start)) { 3222 /* 3223 * Partial overlap, recorded at todrop 3224 * above. 3225 */ 3226 tcp_update_sack_list(tp, 3227 tp->sackblks[0].start, 3228 tp->sackblks[0].end); 3229 } else { 3230 tcp_update_dsack_list(tp, save_start, 3231 save_start + save_tlen); 3232 } 3233 } else if (tlen >= save_tlen) { 3234 /* Update of sackblks. */ 3235 tcp_update_dsack_list(tp, save_start, 3236 save_start + save_tlen); 3237 } else if (tlen > 0) { 3238 tcp_update_dsack_list(tp, save_start, 3239 save_start + tlen); 3240 } 3241 } 3242 tcp_handle_wakeup(tp); 3243 #if 0 3244 /* 3245 * Note the amount of data that peer has sent into 3246 * our window, in order to estimate the sender's 3247 * buffer size. 3248 * XXX: Unused. 3249 */ 3250 if (SEQ_GT(tp->rcv_adv, tp->rcv_nxt)) 3251 len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt); 3252 else 3253 len = so->so_rcv.sb_hiwat; 3254 #endif 3255 } else { 3256 if ((s = tcp_log_addrs(inc, th, NULL, NULL))) { 3257 if (tlen > 0) { 3258 if ((thflags & TH_FIN) != 0) { 3259 log(LOG_DEBUG, "%s; %s: %s: " 3260 "Received %d bytes of data and FIN " 3261 "after having received a FIN, " 3262 "just dropping both\n", 3263 s, __func__, 3264 tcpstates[tp->t_state], tlen); 3265 } else { 3266 log(LOG_DEBUG, "%s; %s: %s: " 3267 "Received %d bytes of data " 3268 "after having received a FIN, " 3269 "just dropping it\n", 3270 s, __func__, 3271 tcpstates[tp->t_state], tlen); 3272 } 3273 } else { 3274 if ((thflags & TH_FIN) != 0) { 3275 log(LOG_DEBUG, "%s; %s: %s: " 3276 "Received FIN " 3277 "after having received a FIN, " 3278 "just dropping it\n", 3279 s, __func__, 3280 tcpstates[tp->t_state]); 3281 } 3282 } 3283 free(s, M_TCPLOG); 3284 } 3285 m_freem(m); 3286 thflags &= ~TH_FIN; 3287 } 3288 3289 /* 3290 * If FIN is received ACK the FIN and let the user know 3291 * that the connection is closing. 3292 */ 3293 if (thflags & TH_FIN) { 3294 if (TCPS_HAVERCVDFIN(tp->t_state) == 0) { 3295 /* The socket upcall is handled by socantrcvmore. */ 3296 socantrcvmore(so); 3297 /* 3298 * If connection is half-synchronized 3299 * (ie NEEDSYN flag on) then delay ACK, 3300 * so it may be piggybacked when SYN is sent. 3301 * Otherwise, since we received a FIN then no 3302 * more input can be expected, send ACK now. 3303 */ 3304 if (tp->t_flags & TF_NEEDSYN) 3305 tp->t_flags |= TF_DELACK; 3306 else 3307 tp->t_flags |= TF_ACKNOW; 3308 tp->rcv_nxt++; 3309 } 3310 switch (tp->t_state) { 3311 /* 3312 * In SYN_RECEIVED and ESTABLISHED STATES 3313 * enter the CLOSE_WAIT state. 3314 */ 3315 case TCPS_SYN_RECEIVED: 3316 tp->t_starttime = ticks; 3317 /* FALLTHROUGH */ 3318 case TCPS_ESTABLISHED: 3319 tcp_state_change(tp, TCPS_CLOSE_WAIT); 3320 break; 3321 3322 /* 3323 * If still in FIN_WAIT_1 STATE FIN has not been acked so 3324 * enter the CLOSING state. 3325 */ 3326 case TCPS_FIN_WAIT_1: 3327 tcp_state_change(tp, TCPS_CLOSING); 3328 break; 3329 3330 /* 3331 * In FIN_WAIT_2 state enter the TIME_WAIT state, 3332 * starting the time-wait timer, turning off the other 3333 * standard timers. 3334 */ 3335 case TCPS_FIN_WAIT_2: 3336 tcp_twstart(tp); 3337 return; 3338 } 3339 } 3340 TCP_PROBE3(debug__input, tp, th, m); 3341 3342 /* 3343 * Return any desired output. 3344 */ 3345 if (needoutput || (tp->t_flags & TF_ACKNOW)) { 3346 (void) tcp_output(tp); 3347 } 3348 check_delack: 3349 INP_WLOCK_ASSERT(inp); 3350 3351 if (tp->t_flags & TF_DELACK) { 3352 tp->t_flags &= ~TF_DELACK; 3353 tcp_timer_activate(tp, TT_DELACK, tcp_delacktime); 3354 } 3355 INP_WUNLOCK(inp); 3356 return; 3357 3358 dropafterack: 3359 /* 3360 * Generate an ACK dropping incoming segment if it occupies 3361 * sequence space, where the ACK reflects our state. 3362 * 3363 * We can now skip the test for the RST flag since all 3364 * paths to this code happen after packets containing 3365 * RST have been dropped. 3366 * 3367 * In the SYN-RECEIVED state, don't send an ACK unless the 3368 * segment we received passes the SYN-RECEIVED ACK test. 3369 * If it fails send a RST. This breaks the loop in the 3370 * "LAND" DoS attack, and also prevents an ACK storm 3371 * between two listening ports that have been sent forged 3372 * SYN segments, each with the source address of the other. 3373 */ 3374 if (tp->t_state == TCPS_SYN_RECEIVED && (thflags & TH_ACK) && 3375 (SEQ_GT(tp->snd_una, th->th_ack) || 3376 SEQ_GT(th->th_ack, tp->snd_max)) ) { 3377 tcp_log_end_status(tp, TCP_EI_STATUS_RST_IN_FRONT); 3378 goto dropwithreset; 3379 } 3380 TCP_PROBE3(debug__input, tp, th, m); 3381 tp->t_flags |= TF_ACKNOW; 3382 (void) tcp_output(tp); 3383 INP_WUNLOCK(inp); 3384 m_freem(m); 3385 return; 3386 3387 dropwithreset: 3388 tcp_dropwithreset(m, th, tp, tlen); 3389 if (tp != NULL) { 3390 INP_WUNLOCK(inp); 3391 } 3392 return; 3393 3394 drop: 3395 /* 3396 * Drop space held by incoming segment and return. 3397 */ 3398 TCP_PROBE3(debug__input, tp, th, m); 3399 if (tp != NULL) { 3400 INP_WUNLOCK(inp); 3401 } 3402 m_freem(m); 3403 } 3404 3405 /* 3406 * Issue RST and make ACK acceptable to originator of segment. 3407 * The mbuf must still include the original packet header. 3408 * tp may be NULL. 3409 */ 3410 void 3411 tcp_dropwithreset(struct mbuf *m, struct tcphdr *th, struct tcpcb *tp, int tlen) 3412 { 3413 #ifdef INET 3414 struct ip *ip; 3415 #endif 3416 #ifdef INET6 3417 struct ip6_hdr *ip6; 3418 #endif 3419 3420 if (tp != NULL) { 3421 INP_LOCK_ASSERT(tptoinpcb(tp)); 3422 } 3423 3424 /* Don't bother if destination was broadcast/multicast. */ 3425 if ((tcp_get_flags(th) & TH_RST) || m->m_flags & (M_BCAST|M_MCAST)) 3426 goto drop; 3427 #ifdef INET6 3428 if (mtod(m, struct ip *)->ip_v == 6) { 3429 ip6 = mtod(m, struct ip6_hdr *); 3430 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || 3431 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) 3432 goto drop; 3433 /* IPv6 anycast check is done at tcp6_input() */ 3434 } 3435 #endif 3436 #if defined(INET) && defined(INET6) 3437 else 3438 #endif 3439 #ifdef INET 3440 { 3441 ip = mtod(m, struct ip *); 3442 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || 3443 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || 3444 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || 3445 in_ifnet_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) 3446 goto drop; 3447 } 3448 #endif 3449 3450 /* Perform bandwidth limiting. */ 3451 if (badport_bandlim(BANDLIM_TCP_RST) < 0) 3452 goto drop; 3453 3454 /* tcp_respond consumes the mbuf chain. */ 3455 if (tcp_get_flags(th) & TH_ACK) { 3456 tcp_respond(tp, mtod(m, void *), th, m, (tcp_seq)0, 3457 th->th_ack, TH_RST); 3458 } else { 3459 if (tcp_get_flags(th) & TH_SYN) 3460 tlen++; 3461 if (tcp_get_flags(th) & TH_FIN) 3462 tlen++; 3463 tcp_respond(tp, mtod(m, void *), th, m, th->th_seq+tlen, 3464 (tcp_seq)0, TH_RST|TH_ACK); 3465 } 3466 return; 3467 drop: 3468 m_freem(m); 3469 } 3470 3471 /* 3472 * Parse TCP options and place in tcpopt. 3473 */ 3474 void 3475 tcp_dooptions(struct tcpopt *to, u_char *cp, int cnt, int flags) 3476 { 3477 int opt, optlen; 3478 3479 to->to_flags = 0; 3480 for (; cnt > 0; cnt -= optlen, cp += optlen) { 3481 opt = cp[0]; 3482 if (opt == TCPOPT_EOL) 3483 break; 3484 if (opt == TCPOPT_NOP) 3485 optlen = 1; 3486 else { 3487 if (cnt < 2) 3488 break; 3489 optlen = cp[1]; 3490 if (optlen < 2 || optlen > cnt) 3491 break; 3492 } 3493 switch (opt) { 3494 case TCPOPT_MAXSEG: 3495 if (optlen != TCPOLEN_MAXSEG) 3496 continue; 3497 if (!(flags & TO_SYN)) 3498 continue; 3499 to->to_flags |= TOF_MSS; 3500 bcopy((char *)cp + 2, 3501 (char *)&to->to_mss, sizeof(to->to_mss)); 3502 to->to_mss = ntohs(to->to_mss); 3503 break; 3504 case TCPOPT_WINDOW: 3505 if (optlen != TCPOLEN_WINDOW) 3506 continue; 3507 if (!(flags & TO_SYN)) 3508 continue; 3509 to->to_flags |= TOF_SCALE; 3510 to->to_wscale = min(cp[2], TCP_MAX_WINSHIFT); 3511 break; 3512 case TCPOPT_TIMESTAMP: 3513 if (optlen != TCPOLEN_TIMESTAMP) 3514 continue; 3515 to->to_flags |= TOF_TS; 3516 bcopy((char *)cp + 2, 3517 (char *)&to->to_tsval, sizeof(to->to_tsval)); 3518 to->to_tsval = ntohl(to->to_tsval); 3519 bcopy((char *)cp + 6, 3520 (char *)&to->to_tsecr, sizeof(to->to_tsecr)); 3521 to->to_tsecr = ntohl(to->to_tsecr); 3522 break; 3523 case TCPOPT_SIGNATURE: 3524 /* 3525 * In order to reply to a host which has set the 3526 * TCP_SIGNATURE option in its initial SYN, we have 3527 * to record the fact that the option was observed 3528 * here for the syncache code to perform the correct 3529 * response. 3530 */ 3531 if (optlen != TCPOLEN_SIGNATURE) 3532 continue; 3533 to->to_flags |= TOF_SIGNATURE; 3534 to->to_signature = cp + 2; 3535 break; 3536 case TCPOPT_SACK_PERMITTED: 3537 if (optlen != TCPOLEN_SACK_PERMITTED) 3538 continue; 3539 if (!(flags & TO_SYN)) 3540 continue; 3541 if (!V_tcp_do_sack) 3542 continue; 3543 to->to_flags |= TOF_SACKPERM; 3544 break; 3545 case TCPOPT_SACK: 3546 if (optlen <= 2 || (optlen - 2) % TCPOLEN_SACK != 0) 3547 continue; 3548 if (flags & TO_SYN) 3549 continue; 3550 to->to_flags |= TOF_SACK; 3551 to->to_nsacks = (optlen - 2) / TCPOLEN_SACK; 3552 to->to_sacks = cp + 2; 3553 TCPSTAT_INC(tcps_sack_rcv_blocks); 3554 break; 3555 case TCPOPT_FAST_OPEN: 3556 /* 3557 * Cookie length validation is performed by the 3558 * server side cookie checking code or the client 3559 * side cookie cache update code. 3560 */ 3561 if (!(flags & TO_SYN)) 3562 continue; 3563 if (!V_tcp_fastopen_client_enable && 3564 !V_tcp_fastopen_server_enable) 3565 continue; 3566 to->to_flags |= TOF_FASTOPEN; 3567 to->to_tfo_len = optlen - 2; 3568 to->to_tfo_cookie = to->to_tfo_len ? cp + 2 : NULL; 3569 break; 3570 default: 3571 continue; 3572 } 3573 } 3574 } 3575 3576 /* 3577 * Pull out of band byte out of a segment so 3578 * it doesn't appear in the user's data queue. 3579 * It is still reflected in the segment length for 3580 * sequencing purposes. 3581 */ 3582 void 3583 tcp_pulloutofband(struct socket *so, struct tcphdr *th, struct mbuf *m, 3584 int off) 3585 { 3586 int cnt = off + th->th_urp - 1; 3587 3588 while (cnt >= 0) { 3589 if (m->m_len > cnt) { 3590 char *cp = mtod(m, caddr_t) + cnt; 3591 struct tcpcb *tp = sototcpcb(so); 3592 3593 INP_WLOCK_ASSERT(tptoinpcb(tp)); 3594 3595 tp->t_iobc = *cp; 3596 tp->t_oobflags |= TCPOOB_HAVEDATA; 3597 bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1)); 3598 m->m_len--; 3599 if (m->m_flags & M_PKTHDR) 3600 m->m_pkthdr.len--; 3601 return; 3602 } 3603 cnt -= m->m_len; 3604 m = m->m_next; 3605 if (m == NULL) 3606 break; 3607 } 3608 panic("tcp_pulloutofband"); 3609 } 3610 3611 /* 3612 * Collect new round-trip time estimate 3613 * and update averages and current timeout. 3614 */ 3615 void 3616 tcp_xmit_timer(struct tcpcb *tp, int rtt) 3617 { 3618 int delta; 3619 3620 INP_WLOCK_ASSERT(tptoinpcb(tp)); 3621 3622 TCPSTAT_INC(tcps_rttupdated); 3623 if (tp->t_rttupdated < UCHAR_MAX) 3624 tp->t_rttupdated++; 3625 #ifdef STATS 3626 stats_voi_update_abs_u32(tp->t_stats, VOI_TCP_RTT, 3627 imax(0, rtt * 1000 / hz)); 3628 #endif 3629 if ((tp->t_srtt != 0) && (tp->t_rxtshift <= TCP_RTT_INVALIDATE)) { 3630 /* 3631 * srtt is stored as fixed point with 5 bits after the 3632 * binary point (i.e., scaled by 8). The following magic 3633 * is equivalent to the smoothing algorithm in rfc793 with 3634 * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed 3635 * point). Adjust rtt to origin 0. 3636 */ 3637 delta = ((rtt - 1) << TCP_DELTA_SHIFT) 3638 - (tp->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT)); 3639 3640 if ((tp->t_srtt += delta) <= 0) 3641 tp->t_srtt = 1; 3642 3643 /* 3644 * We accumulate a smoothed rtt variance (actually, a 3645 * smoothed mean difference), then set the retransmit 3646 * timer to smoothed rtt + 4 times the smoothed variance. 3647 * rttvar is stored as fixed point with 4 bits after the 3648 * binary point (scaled by 16). The following is 3649 * equivalent to rfc793 smoothing with an alpha of .75 3650 * (rttvar = rttvar*3/4 + |delta| / 4). This replaces 3651 * rfc793's wired-in beta. 3652 */ 3653 if (delta < 0) 3654 delta = -delta; 3655 delta -= tp->t_rttvar >> (TCP_RTTVAR_SHIFT - TCP_DELTA_SHIFT); 3656 if ((tp->t_rttvar += delta) <= 0) 3657 tp->t_rttvar = 1; 3658 } else { 3659 /* 3660 * No rtt measurement yet - use the unsmoothed rtt. 3661 * Set the variance to half the rtt (so our first 3662 * retransmit happens at 3*rtt). 3663 */ 3664 tp->t_srtt = rtt << TCP_RTT_SHIFT; 3665 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1); 3666 } 3667 tp->t_rtttime = 0; 3668 tp->t_rxtshift = 0; 3669 3670 /* 3671 * the retransmit should happen at rtt + 4 * rttvar. 3672 * Because of the way we do the smoothing, srtt and rttvar 3673 * will each average +1/2 tick of bias. When we compute 3674 * the retransmit timer, we want 1/2 tick of rounding and 3675 * 1 extra tick because of +-1/2 tick uncertainty in the 3676 * firing of the timer. The bias will give us exactly the 3677 * 1.5 tick we need. But, because the bias is 3678 * statistical, we have to test that we don't drop below 3679 * the minimum feasible timer (which is 2 ticks). 3680 */ 3681 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), 3682 max(tp->t_rttmin, rtt + 2), tcp_rexmit_max); 3683 3684 /* 3685 * We received an ack for a packet that wasn't retransmitted; 3686 * it is probably safe to discard any error indications we've 3687 * received recently. This isn't quite right, but close enough 3688 * for now (a route might have failed after we sent a segment, 3689 * and the return path might not be symmetrical). 3690 */ 3691 tp->t_softerror = 0; 3692 } 3693 3694 /* 3695 * Determine a reasonable value for maxseg size. 3696 * If the route is known, check route for mtu. 3697 * If none, use an mss that can be handled on the outgoing interface 3698 * without forcing IP to fragment. If no route is found, route has no mtu, 3699 * or the destination isn't local, use a default, hopefully conservative 3700 * size (usually 512 or the default IP max size, but no more than the mtu 3701 * of the interface), as we can't discover anything about intervening 3702 * gateways or networks. We also initialize the congestion/slow start 3703 * window to be a single segment if the destination isn't local. 3704 * While looking at the routing entry, we also initialize other path-dependent 3705 * parameters from pre-set or cached values in the routing entry. 3706 * 3707 * NOTE that resulting t_maxseg doesn't include space for TCP options or 3708 * IP options, e.g. IPSEC data, since length of this data may vary, and 3709 * thus it is calculated for every segment separately in tcp_output(). 3710 * 3711 * NOTE that this routine is only called when we process an incoming 3712 * segment, or an ICMP need fragmentation datagram. Outgoing SYN/ACK MSS 3713 * settings are handled in tcp_mssopt(). 3714 */ 3715 void 3716 tcp_mss_update(struct tcpcb *tp, int offer, int mtuoffer, 3717 struct hc_metrics_lite *metricptr, struct tcp_ifcap *cap) 3718 { 3719 int mss = 0; 3720 uint32_t maxmtu = 0; 3721 struct inpcb *inp = tptoinpcb(tp); 3722 struct hc_metrics_lite metrics; 3723 #ifdef INET6 3724 int isipv6 = ((inp->inp_vflag & INP_IPV6) != 0) ? 1 : 0; 3725 size_t min_protoh = isipv6 ? 3726 sizeof (struct ip6_hdr) + sizeof (struct tcphdr) : 3727 sizeof (struct tcpiphdr); 3728 #else 3729 size_t min_protoh = sizeof(struct tcpiphdr); 3730 #endif 3731 3732 INP_WLOCK_ASSERT(inp); 3733 3734 if (tp->t_port) 3735 min_protoh += V_tcp_udp_tunneling_overhead; 3736 if (mtuoffer != -1) { 3737 KASSERT(offer == -1, ("%s: conflict", __func__)); 3738 offer = mtuoffer - min_protoh; 3739 } 3740 3741 /* Initialize. */ 3742 #ifdef INET6 3743 if (isipv6) { 3744 maxmtu = tcp_maxmtu6(&inp->inp_inc, cap); 3745 tp->t_maxseg = V_tcp_v6mssdflt; 3746 } 3747 #endif 3748 #if defined(INET) && defined(INET6) 3749 else 3750 #endif 3751 #ifdef INET 3752 { 3753 maxmtu = tcp_maxmtu(&inp->inp_inc, cap); 3754 tp->t_maxseg = V_tcp_mssdflt; 3755 } 3756 #endif 3757 3758 /* 3759 * No route to sender, stay with default mss and return. 3760 */ 3761 if (maxmtu == 0) { 3762 /* 3763 * In case we return early we need to initialize metrics 3764 * to a defined state as tcp_hc_get() would do for us 3765 * if there was no cache hit. 3766 */ 3767 if (metricptr != NULL) 3768 bzero(metricptr, sizeof(struct hc_metrics_lite)); 3769 return; 3770 } 3771 3772 /* What have we got? */ 3773 switch (offer) { 3774 case 0: 3775 /* 3776 * Offer == 0 means that there was no MSS on the SYN 3777 * segment, in this case we use tcp_mssdflt as 3778 * already assigned to t_maxseg above. 3779 */ 3780 offer = tp->t_maxseg; 3781 break; 3782 3783 case -1: 3784 /* 3785 * Offer == -1 means that we didn't receive SYN yet. 3786 */ 3787 /* FALLTHROUGH */ 3788 3789 default: 3790 /* 3791 * Prevent DoS attack with too small MSS. Round up 3792 * to at least minmss. 3793 */ 3794 offer = max(offer, V_tcp_minmss); 3795 } 3796 3797 if (metricptr == NULL) 3798 metricptr = &metrics; 3799 tcp_hc_get(&inp->inp_inc, metricptr); 3800 3801 /* 3802 * If there's a discovered mtu in tcp hostcache, use it. 3803 * Else, use the link mtu. 3804 */ 3805 if (metricptr->hc_mtu) 3806 mss = min(metricptr->hc_mtu, maxmtu) - min_protoh; 3807 else { 3808 #ifdef INET6 3809 if (isipv6) { 3810 mss = maxmtu - min_protoh; 3811 if (!V_path_mtu_discovery && 3812 !in6_localaddr(&inp->in6p_faddr)) 3813 mss = min(mss, V_tcp_v6mssdflt); 3814 } 3815 #endif 3816 #if defined(INET) && defined(INET6) 3817 else 3818 #endif 3819 #ifdef INET 3820 { 3821 mss = maxmtu - min_protoh; 3822 if (!V_path_mtu_discovery && 3823 !in_localaddr(inp->inp_faddr)) 3824 mss = min(mss, V_tcp_mssdflt); 3825 } 3826 #endif 3827 /* 3828 * XXX - The above conditional (mss = maxmtu - min_protoh) 3829 * probably violates the TCP spec. 3830 * The problem is that, since we don't know the 3831 * other end's MSS, we are supposed to use a conservative 3832 * default. But, if we do that, then MTU discovery will 3833 * never actually take place, because the conservative 3834 * default is much less than the MTUs typically seen 3835 * on the Internet today. For the moment, we'll sweep 3836 * this under the carpet. 3837 * 3838 * The conservative default might not actually be a problem 3839 * if the only case this occurs is when sending an initial 3840 * SYN with options and data to a host we've never talked 3841 * to before. Then, they will reply with an MSS value which 3842 * will get recorded and the new parameters should get 3843 * recomputed. For Further Study. 3844 */ 3845 } 3846 mss = min(mss, offer); 3847 3848 /* 3849 * Sanity check: make sure that maxseg will be large 3850 * enough to allow some data on segments even if the 3851 * all the option space is used (40bytes). Otherwise 3852 * funny things may happen in tcp_output. 3853 * 3854 * XXXGL: shouldn't we reserve space for IP/IPv6 options? 3855 */ 3856 mss = max(mss, 64); 3857 3858 tp->t_maxseg = mss; 3859 if (tp->t_maxseg < V_tcp_mssdflt) { 3860 /* 3861 * The MSS is so small we should not process incoming 3862 * SACK's since we are subject to attack in such a 3863 * case. 3864 */ 3865 tp->t_flags2 |= TF2_PROC_SACK_PROHIBIT; 3866 } else { 3867 tp->t_flags2 &= ~TF2_PROC_SACK_PROHIBIT; 3868 } 3869 3870 } 3871 3872 void 3873 tcp_mss(struct tcpcb *tp, int offer) 3874 { 3875 int mss; 3876 uint32_t bufsize; 3877 struct inpcb *inp = tptoinpcb(tp); 3878 struct socket *so; 3879 struct hc_metrics_lite metrics; 3880 struct tcp_ifcap cap; 3881 3882 KASSERT(tp != NULL, ("%s: tp == NULL", __func__)); 3883 3884 bzero(&cap, sizeof(cap)); 3885 tcp_mss_update(tp, offer, -1, &metrics, &cap); 3886 3887 mss = tp->t_maxseg; 3888 3889 /* 3890 * If there's a pipesize, change the socket buffer to that size, 3891 * don't change if sb_hiwat is different than default (then it 3892 * has been changed on purpose with setsockopt). 3893 * Make the socket buffers an integral number of mss units; 3894 * if the mss is larger than the socket buffer, decrease the mss. 3895 */ 3896 so = inp->inp_socket; 3897 SOCK_SENDBUF_LOCK(so); 3898 if ((so->so_snd.sb_hiwat == V_tcp_sendspace) && metrics.hc_sendpipe) 3899 bufsize = metrics.hc_sendpipe; 3900 else 3901 bufsize = so->so_snd.sb_hiwat; 3902 if (bufsize < mss) 3903 mss = bufsize; 3904 else { 3905 bufsize = roundup(bufsize, mss); 3906 if (bufsize > sb_max) 3907 bufsize = sb_max; 3908 if (bufsize > so->so_snd.sb_hiwat) 3909 (void)sbreserve_locked(so, SO_SND, bufsize, NULL); 3910 } 3911 SOCK_SENDBUF_UNLOCK(so); 3912 /* 3913 * Sanity check: make sure that maxseg will be large 3914 * enough to allow some data on segments even if the 3915 * all the option space is used (40bytes). Otherwise 3916 * funny things may happen in tcp_output. 3917 * 3918 * XXXGL: shouldn't we reserve space for IP/IPv6 options? 3919 */ 3920 tp->t_maxseg = max(mss, 64); 3921 if (tp->t_maxseg < V_tcp_mssdflt) { 3922 /* 3923 * The MSS is so small we should not process incoming 3924 * SACK's since we are subject to attack in such a 3925 * case. 3926 */ 3927 tp->t_flags2 |= TF2_PROC_SACK_PROHIBIT; 3928 } else { 3929 tp->t_flags2 &= ~TF2_PROC_SACK_PROHIBIT; 3930 } 3931 3932 SOCK_RECVBUF_LOCK(so); 3933 if ((so->so_rcv.sb_hiwat == V_tcp_recvspace) && metrics.hc_recvpipe) 3934 bufsize = metrics.hc_recvpipe; 3935 else 3936 bufsize = so->so_rcv.sb_hiwat; 3937 if (bufsize > mss) { 3938 bufsize = roundup(bufsize, mss); 3939 if (bufsize > sb_max) 3940 bufsize = sb_max; 3941 if (bufsize > so->so_rcv.sb_hiwat) 3942 (void)sbreserve_locked(so, SO_RCV, bufsize, NULL); 3943 } 3944 SOCK_RECVBUF_UNLOCK(so); 3945 3946 /* Check the interface for TSO capabilities. */ 3947 if (cap.ifcap & CSUM_TSO) { 3948 tp->t_flags |= TF_TSO; 3949 tp->t_tsomax = cap.tsomax; 3950 tp->t_tsomaxsegcount = cap.tsomaxsegcount; 3951 tp->t_tsomaxsegsize = cap.tsomaxsegsize; 3952 if (cap.ipsec_tso) 3953 tp->t_flags2 |= TF2_IPSEC_TSO; 3954 } 3955 } 3956 3957 /* 3958 * Determine the MSS option to send on an outgoing SYN. 3959 */ 3960 int 3961 tcp_mssopt(struct in_conninfo *inc) 3962 { 3963 int mss = 0; 3964 uint32_t thcmtu = 0; 3965 uint32_t maxmtu = 0; 3966 size_t min_protoh; 3967 3968 KASSERT(inc != NULL, ("tcp_mssopt with NULL in_conninfo pointer")); 3969 3970 #ifdef INET6 3971 if (inc->inc_flags & INC_ISIPV6) { 3972 mss = V_tcp_v6mssdflt; 3973 maxmtu = tcp_maxmtu6(inc, NULL); 3974 min_protoh = sizeof(struct ip6_hdr) + sizeof(struct tcphdr); 3975 } 3976 #endif 3977 #if defined(INET) && defined(INET6) 3978 else 3979 #endif 3980 #ifdef INET 3981 { 3982 mss = V_tcp_mssdflt; 3983 maxmtu = tcp_maxmtu(inc, NULL); 3984 min_protoh = sizeof(struct tcpiphdr); 3985 } 3986 #endif 3987 #if defined(INET6) || defined(INET) 3988 thcmtu = tcp_hc_getmtu(inc); /* IPv4 and IPv6 */ 3989 #endif 3990 3991 if (maxmtu && thcmtu) 3992 mss = min(maxmtu, thcmtu) - min_protoh; 3993 else if (maxmtu || thcmtu) 3994 mss = max(maxmtu, thcmtu) - min_protoh; 3995 3996 return (mss); 3997 } 3998 3999 void 4000 tcp_do_prr_ack(struct tcpcb *tp, struct tcphdr *th, struct tcpopt *to, 4001 sackstatus_t sack_changed, u_int *maxsegp) 4002 { 4003 int snd_cnt = 0, del_data = 0, pipe = 0; 4004 u_int maxseg; 4005 bool safe_ack; 4006 4007 INP_WLOCK_ASSERT(tptoinpcb(tp)); 4008 4009 if (*maxsegp == 0) { 4010 *maxsegp = tcp_maxseg(tp); 4011 } 4012 maxseg = *maxsegp; 4013 /* 4014 * Compute the amount of data that this ACK is indicating 4015 * (del_data) and an estimate of how many bytes are in the 4016 * network. 4017 */ 4018 if (tcp_is_sack_recovery(tp, to) || 4019 (IN_CONGRECOVERY(tp->t_flags) && 4020 !IN_FASTRECOVERY(tp->t_flags))) { 4021 del_data = tp->sackhint.delivered_data; 4022 pipe = tcp_compute_pipe(tp); 4023 } else { 4024 if (tp->sackhint.prr_delivered < (tcprexmtthresh * maxseg + 4025 tp->snd_recover - tp->snd_una)) { 4026 del_data = maxseg; 4027 } 4028 pipe = imax(0, tp->snd_max - tp->snd_una - 4029 imin(INT_MAX / 65536, tp->t_dupacks) * maxseg); 4030 } 4031 4032 if (del_data == 0) 4033 return; 4034 4035 tp->sackhint.prr_delivered += del_data; 4036 /* 4037 * Proportional Rate Reduction 4038 */ 4039 if (pipe >= tp->snd_ssthresh) { 4040 if (tp->sackhint.recover_fs == 0) 4041 tp->sackhint.recover_fs = 4042 imax(1, tp->snd_nxt - tp->snd_una); 4043 snd_cnt = howmany((long)tp->sackhint.prr_delivered * 4044 tp->snd_ssthresh, tp->sackhint.recover_fs) - 4045 tp->sackhint.prr_out + maxseg - 1; 4046 } else { 4047 safe_ack = SEQ_GT(th->th_ack, tp->snd_una) && (sack_changed != SACK_NEWLOSS); 4048 snd_cnt = imax(tp->sackhint.prr_delivered - tp->sackhint.prr_out, del_data); 4049 if (safe_ack) { 4050 snd_cnt += maxseg; 4051 } 4052 snd_cnt = imin(tp->snd_ssthresh - pipe, snd_cnt); 4053 } 4054 4055 if (tp->sackhint.prr_out == 0 && snd_cnt == 0) { 4056 snd_cnt = maxseg; 4057 } 4058 snd_cnt = imax(snd_cnt, 0) / maxseg; 4059 /* 4060 * Send snd_cnt new data into the network in response to this ack. 4061 * If there is going to be a SACK retransmission, adjust snd_cwnd 4062 * accordingly. 4063 */ 4064 if (IN_FASTRECOVERY(tp->t_flags)) { 4065 if (tcp_is_sack_recovery(tp, to)) { 4066 tp->snd_cwnd = pipe - del_data + (snd_cnt * maxseg); 4067 } else { 4068 tp->snd_cwnd = (tp->snd_max - tp->snd_una) + 4069 (snd_cnt * maxseg); 4070 } 4071 } else if (IN_CONGRECOVERY(tp->t_flags)) { 4072 tp->snd_cwnd = pipe - del_data + (snd_cnt * maxseg); 4073 } 4074 tp->snd_cwnd = imax(maxseg, tp->snd_cwnd); 4075 } 4076 4077 /* 4078 * On a partial ack arrives, force the retransmission of the 4079 * next unacknowledged segment. Do not clear tp->t_dupacks. 4080 * By setting snd_nxt to ti_ack, this forces retransmission timer to 4081 * be started again. 4082 */ 4083 void 4084 tcp_newreno_partial_ack(struct tcpcb *tp, struct tcphdr *th) 4085 { 4086 tcp_seq onxt = tp->snd_nxt; 4087 uint32_t ocwnd = tp->snd_cwnd; 4088 u_int maxseg = tcp_maxseg(tp); 4089 4090 INP_WLOCK_ASSERT(tptoinpcb(tp)); 4091 4092 tcp_timer_activate(tp, TT_REXMT, 0); 4093 tp->t_rtttime = 0; 4094 if (IN_FASTRECOVERY(tp->t_flags)) { 4095 tp->snd_nxt = th->th_ack; 4096 /* 4097 * Set snd_cwnd to one segment beyond acknowledged offset. 4098 * (tp->snd_una has not yet been updated when this function is called.) 4099 */ 4100 tp->snd_cwnd = maxseg + BYTES_THIS_ACK(tp, th); 4101 tp->t_flags |= TF_ACKNOW; 4102 (void) tcp_output(tp); 4103 tp->snd_cwnd = ocwnd; 4104 if (SEQ_GT(onxt, tp->snd_nxt)) 4105 tp->snd_nxt = onxt; 4106 } 4107 /* 4108 * Partial window deflation. Relies on fact that tp->snd_una 4109 * not updated yet. 4110 */ 4111 if (tp->snd_cwnd > BYTES_THIS_ACK(tp, th)) 4112 tp->snd_cwnd -= BYTES_THIS_ACK(tp, th); 4113 else 4114 tp->snd_cwnd = 0; 4115 tp->snd_cwnd += maxseg; 4116 } 4117 4118 int 4119 tcp_compute_pipe(struct tcpcb *tp) 4120 { 4121 int pipe; 4122 4123 if (tp->t_fb->tfb_compute_pipe != NULL) { 4124 pipe = (*tp->t_fb->tfb_compute_pipe)(tp); 4125 } else { 4126 pipe = tp->snd_max - tp->snd_una + 4127 tp->sackhint.sack_bytes_rexmit - 4128 tp->sackhint.sacked_bytes - 4129 tp->sackhint.lost_bytes; 4130 } 4131 return (imax(pipe, 0)); 4132 } 4133 4134 uint32_t 4135 tcp_compute_initwnd(uint32_t maxseg) 4136 { 4137 /* 4138 * Calculate the Initial Window, also used as Restart Window 4139 * 4140 * RFC5681 Section 3.1 specifies the default conservative values. 4141 * RFC3390 specifies slightly more aggressive values. 4142 * RFC6928 increases it to ten segments. 4143 * Support for user specified value for initial flight size. 4144 */ 4145 if (V_tcp_initcwnd_segments) 4146 return min(V_tcp_initcwnd_segments * maxseg, 4147 max(2 * maxseg, V_tcp_initcwnd_segments * 1460)); 4148 else if (V_tcp_do_rfc3390) 4149 return min(4 * maxseg, max(2 * maxseg, 4380)); 4150 else { 4151 /* Per RFC5681 Section 3.1 */ 4152 if (maxseg > 2190) 4153 return (2 * maxseg); 4154 else if (maxseg > 1095) 4155 return (3 * maxseg); 4156 else 4157 return (4 * maxseg); 4158 } 4159 } 4160