| 1 | /* |
| 2 | * Copyright (c) 2002, 2003, 2004 Jeffrey M. Hsu. All rights reserved. |
| 3 | * Copyright (c) 2002, 2003, 2004 The DragonFly Project. All rights reserved. |
| 4 | * |
| 5 | * This code is derived from software contributed to The DragonFly Project |
| 6 | * by Jeffrey M. Hsu. |
| 7 | * |
| 8 | * Redistribution and use in source and binary forms, with or without |
| 9 | * modification, are permitted provided that the following conditions |
| 10 | * are met: |
| 11 | * 1. Redistributions of source code must retain the above copyright |
| 12 | * notice, this list of conditions and the following disclaimer. |
| 13 | * 2. Redistributions in binary form must reproduce the above copyright |
| 14 | * notice, this list of conditions and the following disclaimer in the |
| 15 | * documentation and/or other materials provided with the distribution. |
| 16 | * 3. Neither the name of The DragonFly Project nor the names of its |
| 17 | * contributors may be used to endorse or promote products derived |
| 18 | * from this software without specific, prior written permission. |
| 19 | * |
| 20 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| 21 | * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| 22 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
| 23 | * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
| 24 | * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
| 25 | * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, |
| 26 | * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
| 27 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED |
| 28 | * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, |
| 29 | * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT |
| 30 | * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 31 | * SUCH DAMAGE. |
| 32 | */ |
| 33 | |
| 34 | /* |
| 35 | * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995 |
| 36 | * The Regents of the University of California. All rights reserved. |
| 37 | * |
| 38 | * Redistribution and use in source and binary forms, with or without |
| 39 | * modification, are permitted provided that the following conditions |
| 40 | * are met: |
| 41 | * 1. Redistributions of source code must retain the above copyright |
| 42 | * notice, this list of conditions and the following disclaimer. |
| 43 | * 2. Redistributions in binary form must reproduce the above copyright |
| 44 | * notice, this list of conditions and the following disclaimer in the |
| 45 | * documentation and/or other materials provided with the distribution. |
| 46 | * 3. All advertising materials mentioning features or use of this software |
| 47 | * must display the following acknowledgement: |
| 48 | * This product includes software developed by the University of |
| 49 | * California, Berkeley and its contributors. |
| 50 | * 4. Neither the name of the University nor the names of its contributors |
| 51 | * may be used to endorse or promote products derived from this software |
| 52 | * without specific prior written permission. |
| 53 | * |
| 54 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
| 55 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 56 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 57 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
| 58 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| 59 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| 60 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 61 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| 62 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| 63 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 64 | * SUCH DAMAGE. |
| 65 | * |
| 66 | * @(#)tcp_input.c 8.12 (Berkeley) 5/24/95 |
| 67 | * $FreeBSD: src/sys/netinet/tcp_input.c,v 1.107.2.38 2003/05/21 04:46:41 cjc Exp $ |
| 68 | * $DragonFly: src/sys/netinet/tcp_input.c,v 1.68 2008/08/22 09:14:17 sephe Exp $ |
| 69 | */ |
| 70 | |
| 71 | #include "opt_ipfw.h" /* for ipfw_fwd */ |
| 72 | #include "opt_inet.h" |
| 73 | #include "opt_inet6.h" |
| 74 | #include "opt_ipsec.h" |
| 75 | #include "opt_tcpdebug.h" |
| 76 | #include "opt_tcp_input.h" |
| 77 | |
| 78 | #include <sys/param.h> |
| 79 | #include <sys/systm.h> |
| 80 | #include <sys/kernel.h> |
| 81 | #include <sys/sysctl.h> |
| 82 | #include <sys/malloc.h> |
| 83 | #include <sys/mbuf.h> |
| 84 | #include <sys/proc.h> /* for proc0 declaration */ |
| 85 | #include <sys/protosw.h> |
| 86 | #include <sys/socket.h> |
| 87 | #include <sys/socketvar.h> |
| 88 | #include <sys/syslog.h> |
| 89 | #include <sys/in_cksum.h> |
| 90 | |
| 91 | #include <sys/socketvar2.h> |
| 92 | |
| 93 | #include <machine/cpu.h> /* before tcp_seq.h, for tcp_random18() */ |
| 94 | #include <machine/stdarg.h> |
| 95 | |
| 96 | #include <net/if.h> |
| 97 | #include <net/route.h> |
| 98 | |
| 99 | #include <netinet/in.h> |
| 100 | #include <netinet/in_systm.h> |
| 101 | #include <netinet/ip.h> |
| 102 | #include <netinet/ip_icmp.h> /* for ICMP_BANDLIM */ |
| 103 | #include <netinet/in_var.h> |
| 104 | #include <netinet/icmp_var.h> /* for ICMP_BANDLIM */ |
| 105 | #include <netinet/in_pcb.h> |
| 106 | #include <netinet/ip_var.h> |
| 107 | #include <netinet/ip6.h> |
| 108 | #include <netinet/icmp6.h> |
| 109 | #include <netinet6/nd6.h> |
| 110 | #include <netinet6/ip6_var.h> |
| 111 | #include <netinet6/in6_pcb.h> |
| 112 | #include <netinet/tcp.h> |
| 113 | #include <netinet/tcp_fsm.h> |
| 114 | #include <netinet/tcp_seq.h> |
| 115 | #include <netinet/tcp_timer.h> |
| 116 | #include <netinet/tcp_timer2.h> |
| 117 | #include <netinet/tcp_var.h> |
| 118 | #include <netinet6/tcp6_var.h> |
| 119 | #include <netinet/tcpip.h> |
| 120 | |
| 121 | #ifdef TCPDEBUG |
| 122 | #include <netinet/tcp_debug.h> |
| 123 | |
| 124 | u_char tcp_saveipgen[40]; /* the size must be of max ip header, now IPv6 */ |
| 125 | struct tcphdr tcp_savetcp; |
| 126 | #endif |
| 127 | |
| 128 | #ifdef FAST_IPSEC |
| 129 | #include <netproto/ipsec/ipsec.h> |
| 130 | #include <netproto/ipsec/ipsec6.h> |
| 131 | #endif |
| 132 | |
| 133 | #ifdef IPSEC |
| 134 | #include <netinet6/ipsec.h> |
| 135 | #include <netinet6/ipsec6.h> |
| 136 | #include <netproto/key/key.h> |
| 137 | #endif |
| 138 | |
| 139 | MALLOC_DEFINE(M_TSEGQ, "tseg_qent", "TCP segment queue entry"); |
| 140 | |
| 141 | static int log_in_vain = 0; |
| 142 | SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_in_vain, CTLFLAG_RW, |
| 143 | &log_in_vain, 0, "Log all incoming TCP connections"); |
| 144 | |
| 145 | static int blackhole = 0; |
| 146 | SYSCTL_INT(_net_inet_tcp, OID_AUTO, blackhole, CTLFLAG_RW, |
| 147 | &blackhole, 0, "Do not send RST when dropping refused connections"); |
| 148 | |
| 149 | int tcp_delack_enabled = 1; |
| 150 | SYSCTL_INT(_net_inet_tcp, OID_AUTO, delayed_ack, CTLFLAG_RW, |
| 151 | &tcp_delack_enabled, 0, |
| 152 | "Delay ACK to try and piggyback it onto a data packet"); |
| 153 | |
| 154 | #ifdef TCP_DROP_SYNFIN |
| 155 | static int drop_synfin = 0; |
| 156 | SYSCTL_INT(_net_inet_tcp, OID_AUTO, drop_synfin, CTLFLAG_RW, |
| 157 | &drop_synfin, 0, "Drop TCP packets with SYN+FIN set"); |
| 158 | #endif |
| 159 | |
| 160 | static int tcp_do_limitedtransmit = 1; |
| 161 | SYSCTL_INT(_net_inet_tcp, OID_AUTO, limitedtransmit, CTLFLAG_RW, |
| 162 | &tcp_do_limitedtransmit, 0, "Enable RFC 3042 (Limited Transmit)"); |
| 163 | |
| 164 | static int tcp_do_early_retransmit = 1; |
| 165 | SYSCTL_INT(_net_inet_tcp, OID_AUTO, earlyretransmit, CTLFLAG_RW, |
| 166 | &tcp_do_early_retransmit, 0, "Early retransmit"); |
| 167 | |
| 168 | int tcp_aggregate_acks = 1; |
| 169 | SYSCTL_INT(_net_inet_tcp, OID_AUTO, aggregate_acks, CTLFLAG_RW, |
| 170 | &tcp_aggregate_acks, 0, "Aggregate built-up acks into one ack"); |
| 171 | |
| 172 | int tcp_do_rfc3390 = 1; |
| 173 | SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3390, CTLFLAG_RW, |
| 174 | &tcp_do_rfc3390, 0, |
| 175 | "Enable RFC 3390 (Increasing TCP's Initial Congestion Window)"); |
| 176 | |
| 177 | static int tcp_do_eifel_detect = 1; |
| 178 | SYSCTL_INT(_net_inet_tcp, OID_AUTO, eifel, CTLFLAG_RW, |
| 179 | &tcp_do_eifel_detect, 0, "Eifel detection algorithm (RFC 3522)"); |
| 180 | |
| 181 | static int tcp_do_abc = 1; |
| 182 | SYSCTL_INT(_net_inet_tcp, OID_AUTO, abc, CTLFLAG_RW, |
| 183 | &tcp_do_abc, 0, |
| 184 | "TCP Appropriate Byte Counting (RFC 3465)"); |
| 185 | |
| 186 | /* |
| 187 | * Define as tunable for easy testing with SACK on and off. |
| 188 | * Warning: do not change setting in the middle of an existing active TCP flow, |
| 189 | * else strange things might happen to that flow. |
| 190 | */ |
| 191 | int tcp_do_sack = 1; |
| 192 | SYSCTL_INT(_net_inet_tcp, OID_AUTO, sack, CTLFLAG_RW, |
| 193 | &tcp_do_sack, 0, "Enable SACK Algorithms"); |
| 194 | |
| 195 | int tcp_do_smartsack = 1; |
| 196 | SYSCTL_INT(_net_inet_tcp, OID_AUTO, smartsack, CTLFLAG_RW, |
| 197 | &tcp_do_smartsack, 0, "Enable Smart SACK Algorithms"); |
| 198 | |
| 199 | SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass, CTLFLAG_RW, 0, |
| 200 | "TCP Segment Reassembly Queue"); |
| 201 | |
| 202 | int tcp_reass_maxseg = 0; |
| 203 | SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RD, |
| 204 | &tcp_reass_maxseg, 0, |
| 205 | "Global maximum number of TCP Segments in Reassembly Queue"); |
| 206 | |
| 207 | int tcp_reass_qsize = 0; |
| 208 | SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, cursegments, CTLFLAG_RD, |
| 209 | &tcp_reass_qsize, 0, |
| 210 | "Global number of TCP Segments currently in Reassembly Queue"); |
| 211 | |
| 212 | static int tcp_reass_overflows = 0; |
| 213 | SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, overflows, CTLFLAG_RD, |
| 214 | &tcp_reass_overflows, 0, |
| 215 | "Global number of TCP Segment Reassembly Queue Overflows"); |
| 216 | |
| 217 | int tcp_do_autorcvbuf = 1; |
| 218 | SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_auto, CTLFLAG_RW, |
| 219 | &tcp_do_autorcvbuf, 0, "Enable automatic receive buffer sizing"); |
| 220 | |
| 221 | int tcp_autorcvbuf_inc = 16*1024; |
| 222 | SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_inc, CTLFLAG_RW, |
| 223 | &tcp_autorcvbuf_inc, 0, |
| 224 | "Incrementor step size of automatic receive buffer"); |
| 225 | |
| 226 | int tcp_autorcvbuf_max = 2*1024*1024; |
| 227 | SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_max, CTLFLAG_RW, |
| 228 | &tcp_autorcvbuf_max, 0, "Max size of automatic receive buffer"); |
| 229 | |
| 230 | |
| 231 | static void tcp_dooptions(struct tcpopt *, u_char *, int, boolean_t); |
| 232 | static void tcp_pulloutofband(struct socket *, |
| 233 | struct tcphdr *, struct mbuf *, int); |
| 234 | static int tcp_reass(struct tcpcb *, struct tcphdr *, int *, |
| 235 | struct mbuf *); |
| 236 | static void tcp_xmit_timer(struct tcpcb *, int); |
| 237 | static void tcp_newreno_partial_ack(struct tcpcb *, struct tcphdr *, int); |
| 238 | static void tcp_sack_rexmt(struct tcpcb *, struct tcphdr *); |
| 239 | |
| 240 | /* Neighbor Discovery, Neighbor Unreachability Detection Upper layer hint. */ |
| 241 | #ifdef INET6 |
| 242 | #define ND6_HINT(tp) \ |
| 243 | do { \ |
| 244 | if ((tp) && (tp)->t_inpcb && \ |
| 245 | ((tp)->t_inpcb->inp_vflag & INP_IPV6) && \ |
| 246 | (tp)->t_inpcb->in6p_route.ro_rt) \ |
| 247 | nd6_nud_hint((tp)->t_inpcb->in6p_route.ro_rt, NULL, 0); \ |
| 248 | } while (0) |
| 249 | #else |
| 250 | #define ND6_HINT(tp) |
| 251 | #endif |
| 252 | |
| 253 | /* |
| 254 | * Indicate whether this ack should be delayed. We can delay the ack if |
| 255 | * - delayed acks are enabled and |
| 256 | * - there is no delayed ack timer in progress and |
| 257 | * - our last ack wasn't a 0-sized window. We never want to delay |
| 258 | * the ack that opens up a 0-sized window. |
| 259 | */ |
| 260 | #define DELAY_ACK(tp) \ |
| 261 | (tcp_delack_enabled && !tcp_callout_pending(tp, tp->tt_delack) && \ |
| 262 | !(tp->t_flags & TF_RXWIN0SENT)) |
| 263 | |
| 264 | #define acceptable_window_update(tp, th, tiwin) \ |
| 265 | (SEQ_LT(tp->snd_wl1, th->th_seq) || \ |
| 266 | (tp->snd_wl1 == th->th_seq && \ |
| 267 | (SEQ_LT(tp->snd_wl2, th->th_ack) || \ |
| 268 | (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd)))) |
| 269 | |
| 270 | static int |
| 271 | tcp_reass(struct tcpcb *tp, struct tcphdr *th, int *tlenp, struct mbuf *m) |
| 272 | { |
| 273 | struct tseg_qent *q; |
| 274 | struct tseg_qent *p = NULL; |
| 275 | struct tseg_qent *te; |
| 276 | struct socket *so = tp->t_inpcb->inp_socket; |
| 277 | int flags; |
| 278 | |
| 279 | /* |
| 280 | * Call with th == NULL after become established to |
| 281 | * force pre-ESTABLISHED data up to user socket. |
| 282 | */ |
| 283 | if (th == NULL) |
| 284 | goto present; |
| 285 | |
| 286 | /* |
| 287 | * Limit the number of segments in the reassembly queue to prevent |
| 288 | * holding on to too many segments (and thus running out of mbufs). |
| 289 | * Make sure to let the missing segment through which caused this |
| 290 | * queue. Always keep one global queue entry spare to be able to |
| 291 | * process the missing segment. |
| 292 | */ |
| 293 | if (th->th_seq != tp->rcv_nxt && |
| 294 | tcp_reass_qsize + 1 >= tcp_reass_maxseg) { |
| 295 | tcp_reass_overflows++; |
| 296 | tcpstat.tcps_rcvmemdrop++; |
| 297 | m_freem(m); |
| 298 | /* no SACK block to report */ |
| 299 | tp->reportblk.rblk_start = tp->reportblk.rblk_end; |
| 300 | return (0); |
| 301 | } |
| 302 | |
| 303 | /* Allocate a new queue entry. */ |
| 304 | MALLOC(te, struct tseg_qent *, sizeof(struct tseg_qent), M_TSEGQ, |
| 305 | M_INTWAIT | M_NULLOK); |
| 306 | if (te == NULL) { |
| 307 | tcpstat.tcps_rcvmemdrop++; |
| 308 | m_freem(m); |
| 309 | /* no SACK block to report */ |
| 310 | tp->reportblk.rblk_start = tp->reportblk.rblk_end; |
| 311 | return (0); |
| 312 | } |
| 313 | atomic_add_int(&tcp_reass_qsize, 1); |
| 314 | |
| 315 | /* |
| 316 | * Find a segment which begins after this one does. |
| 317 | */ |
| 318 | LIST_FOREACH(q, &tp->t_segq, tqe_q) { |
| 319 | if (SEQ_GT(q->tqe_th->th_seq, th->th_seq)) |
| 320 | break; |
| 321 | p = q; |
| 322 | } |
| 323 | |
| 324 | /* |
| 325 | * If there is a preceding segment, it may provide some of |
| 326 | * our data already. If so, drop the data from the incoming |
| 327 | * segment. If it provides all of our data, drop us. |
| 328 | */ |
| 329 | if (p != NULL) { |
| 330 | tcp_seq_diff_t i; |
| 331 | |
| 332 | /* conversion to int (in i) handles seq wraparound */ |
| 333 | i = p->tqe_th->th_seq + p->tqe_len - th->th_seq; |
| 334 | if (i > 0) { /* overlaps preceding segment */ |
| 335 | tp->t_flags |= (TF_DUPSEG | TF_ENCLOSESEG); |
| 336 | /* enclosing block starts w/ preceding segment */ |
| 337 | tp->encloseblk.rblk_start = p->tqe_th->th_seq; |
| 338 | if (i >= *tlenp) { |
| 339 | /* preceding encloses incoming segment */ |
| 340 | tp->encloseblk.rblk_end = p->tqe_th->th_seq + |
| 341 | p->tqe_len; |
| 342 | tcpstat.tcps_rcvduppack++; |
| 343 | tcpstat.tcps_rcvdupbyte += *tlenp; |
| 344 | m_freem(m); |
| 345 | kfree(te, M_TSEGQ); |
| 346 | atomic_add_int(&tcp_reass_qsize, -1); |
| 347 | /* |
| 348 | * Try to present any queued data |
| 349 | * at the left window edge to the user. |
| 350 | * This is needed after the 3-WHS |
| 351 | * completes. |
| 352 | */ |
| 353 | goto present; /* ??? */ |
| 354 | } |
| 355 | m_adj(m, i); |
| 356 | *tlenp -= i; |
| 357 | th->th_seq += i; |
| 358 | /* incoming segment end is enclosing block end */ |
| 359 | tp->encloseblk.rblk_end = th->th_seq + *tlenp + |
| 360 | ((th->th_flags & TH_FIN) != 0); |
| 361 | /* trim end of reported D-SACK block */ |
| 362 | tp->reportblk.rblk_end = th->th_seq; |
| 363 | } |
| 364 | } |
| 365 | tcpstat.tcps_rcvoopack++; |
| 366 | tcpstat.tcps_rcvoobyte += *tlenp; |
| 367 | |
| 368 | /* |
| 369 | * While we overlap succeeding segments trim them or, |
| 370 | * if they are completely covered, dequeue them. |
| 371 | */ |
| 372 | while (q) { |
| 373 | tcp_seq_diff_t i = (th->th_seq + *tlenp) - q->tqe_th->th_seq; |
| 374 | tcp_seq qend = q->tqe_th->th_seq + q->tqe_len; |
| 375 | struct tseg_qent *nq; |
| 376 | |
| 377 | if (i <= 0) |
| 378 | break; |
| 379 | if (!(tp->t_flags & TF_DUPSEG)) { /* first time through */ |
| 380 | tp->t_flags |= (TF_DUPSEG | TF_ENCLOSESEG); |
| 381 | tp->encloseblk = tp->reportblk; |
| 382 | /* report trailing duplicate D-SACK segment */ |
| 383 | tp->reportblk.rblk_start = q->tqe_th->th_seq; |
| 384 | } |
| 385 | if ((tp->t_flags & TF_ENCLOSESEG) && |
| 386 | SEQ_GT(qend, tp->encloseblk.rblk_end)) { |
| 387 | /* extend enclosing block if one exists */ |
| 388 | tp->encloseblk.rblk_end = qend; |
| 389 | } |
| 390 | if (i < q->tqe_len) { |
| 391 | q->tqe_th->th_seq += i; |
| 392 | q->tqe_len -= i; |
| 393 | m_adj(q->tqe_m, i); |
| 394 | break; |
| 395 | } |
| 396 | |
| 397 | nq = LIST_NEXT(q, tqe_q); |
| 398 | LIST_REMOVE(q, tqe_q); |
| 399 | m_freem(q->tqe_m); |
| 400 | kfree(q, M_TSEGQ); |
| 401 | atomic_add_int(&tcp_reass_qsize, -1); |
| 402 | q = nq; |
| 403 | } |
| 404 | |
| 405 | /* Insert the new segment queue entry into place. */ |
| 406 | te->tqe_m = m; |
| 407 | te->tqe_th = th; |
| 408 | te->tqe_len = *tlenp; |
| 409 | |
| 410 | /* check if can coalesce with following segment */ |
| 411 | if (q != NULL && (th->th_seq + *tlenp == q->tqe_th->th_seq)) { |
| 412 | tcp_seq tend = te->tqe_th->th_seq + te->tqe_len; |
| 413 | |
| 414 | te->tqe_len += q->tqe_len; |
| 415 | if (q->tqe_th->th_flags & TH_FIN) |
| 416 | te->tqe_th->th_flags |= TH_FIN; |
| 417 | m_cat(te->tqe_m, q->tqe_m); |
| 418 | tp->encloseblk.rblk_end = tend; |
| 419 | /* |
| 420 | * When not reporting a duplicate segment, use |
| 421 | * the larger enclosing block as the SACK block. |
| 422 | */ |
| 423 | if (!(tp->t_flags & TF_DUPSEG)) |
| 424 | tp->reportblk.rblk_end = tend; |
| 425 | LIST_REMOVE(q, tqe_q); |
| 426 | kfree(q, M_TSEGQ); |
| 427 | atomic_add_int(&tcp_reass_qsize, -1); |
| 428 | } |
| 429 | |
| 430 | if (p == NULL) { |
| 431 | LIST_INSERT_HEAD(&tp->t_segq, te, tqe_q); |
| 432 | } else { |
| 433 | /* check if can coalesce with preceding segment */ |
| 434 | if (p->tqe_th->th_seq + p->tqe_len == th->th_seq) { |
| 435 | p->tqe_len += te->tqe_len; |
| 436 | m_cat(p->tqe_m, te->tqe_m); |
| 437 | tp->encloseblk.rblk_start = p->tqe_th->th_seq; |
| 438 | /* |
| 439 | * When not reporting a duplicate segment, use |
| 440 | * the larger enclosing block as the SACK block. |
| 441 | */ |
| 442 | if (!(tp->t_flags & TF_DUPSEG)) |
| 443 | tp->reportblk.rblk_start = p->tqe_th->th_seq; |
| 444 | kfree(te, M_TSEGQ); |
| 445 | atomic_add_int(&tcp_reass_qsize, -1); |
| 446 | } else { |
| 447 | LIST_INSERT_AFTER(p, te, tqe_q); |
| 448 | } |
| 449 | } |
| 450 | |
| 451 | present: |
| 452 | /* |
| 453 | * Present data to user, advancing rcv_nxt through |
| 454 | * completed sequence space. |
| 455 | */ |
| 456 | if (!TCPS_HAVEESTABLISHED(tp->t_state)) |
| 457 | return (0); |
| 458 | q = LIST_FIRST(&tp->t_segq); |
| 459 | if (q == NULL || q->tqe_th->th_seq != tp->rcv_nxt) |
| 460 | return (0); |
| 461 | tp->rcv_nxt += q->tqe_len; |
| 462 | if (!(tp->t_flags & TF_DUPSEG)) { |
| 463 | /* no SACK block to report since ACK advanced */ |
| 464 | tp->reportblk.rblk_start = tp->reportblk.rblk_end; |
| 465 | } |
| 466 | /* no enclosing block to report since ACK advanced */ |
| 467 | tp->t_flags &= ~TF_ENCLOSESEG; |
| 468 | flags = q->tqe_th->th_flags & TH_FIN; |
| 469 | LIST_REMOVE(q, tqe_q); |
| 470 | KASSERT(LIST_EMPTY(&tp->t_segq) || |
| 471 | LIST_FIRST(&tp->t_segq)->tqe_th->th_seq != tp->rcv_nxt, |
| 472 | ("segment not coalesced")); |
| 473 | if (so->so_state & SS_CANTRCVMORE) { |
| 474 | m_freem(q->tqe_m); |
| 475 | } else { |
| 476 | lwkt_gettoken(&so->so_rcv.ssb_token); |
| 477 | ssb_appendstream(&so->so_rcv, q->tqe_m); |
| 478 | lwkt_reltoken(&so->so_rcv.ssb_token); |
| 479 | } |
| 480 | kfree(q, M_TSEGQ); |
| 481 | atomic_add_int(&tcp_reass_qsize, -1); |
| 482 | ND6_HINT(tp); |
| 483 | sorwakeup(so); |
| 484 | return (flags); |
| 485 | } |
| 486 | |
| 487 | /* |
| 488 | * TCP input routine, follows pages 65-76 of the |
| 489 | * protocol specification dated September, 1981 very closely. |
| 490 | */ |
| 491 | #ifdef INET6 |
| 492 | int |
| 493 | tcp6_input(struct mbuf **mp, int *offp, int proto) |
| 494 | { |
| 495 | struct mbuf *m = *mp; |
| 496 | struct in6_ifaddr *ia6; |
| 497 | |
| 498 | IP6_EXTHDR_CHECK(m, *offp, sizeof(struct tcphdr), IPPROTO_DONE); |
| 499 | |
| 500 | /* |
| 501 | * draft-itojun-ipv6-tcp-to-anycast |
| 502 | * better place to put this in? |
| 503 | */ |
| 504 | ia6 = ip6_getdstifaddr(m); |
| 505 | if (ia6 && (ia6->ia6_flags & IN6_IFF_ANYCAST)) { |
| 506 | struct ip6_hdr *ip6; |
| 507 | |
| 508 | ip6 = mtod(m, struct ip6_hdr *); |
| 509 | icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR, |
| 510 | offsetof(struct ip6_hdr, ip6_dst)); |
| 511 | return (IPPROTO_DONE); |
| 512 | } |
| 513 | |
| 514 | tcp_input(mp, offp, proto); |
| 515 | return (IPPROTO_DONE); |
| 516 | } |
| 517 | #endif |
| 518 | |
| 519 | int |
| 520 | tcp_input(struct mbuf **mp, int *offp, int proto) |
| 521 | { |
| 522 | int off0; |
| 523 | struct tcphdr *th; |
| 524 | struct ip *ip = NULL; |
| 525 | struct ipovly *ipov; |
| 526 | struct inpcb *inp = NULL; |
| 527 | u_char *optp = NULL; |
| 528 | int optlen = 0; |
| 529 | int tlen, off; |
| 530 | int len = 0; |
| 531 | int drop_hdrlen; |
| 532 | struct tcpcb *tp = NULL; |
| 533 | int thflags; |
| 534 | struct socket *so = 0; |
| 535 | int todrop, acked; |
| 536 | boolean_t ourfinisacked, needoutput = FALSE; |
| 537 | u_long tiwin; |
| 538 | int recvwin; |
| 539 | struct tcpopt to; /* options in this segment */ |
| 540 | struct sockaddr_in *next_hop = NULL; |
| 541 | int rstreason; /* For badport_bandlim accounting purposes */ |
| 542 | int cpu; |
| 543 | struct ip6_hdr *ip6 = NULL; |
| 544 | struct mbuf *m; |
| 545 | #ifdef INET6 |
| 546 | boolean_t isipv6; |
| 547 | #else |
| 548 | const boolean_t isipv6 = FALSE; |
| 549 | #endif |
| 550 | #ifdef TCPDEBUG |
| 551 | short ostate = 0; |
| 552 | #endif |
| 553 | |
| 554 | off0 = *offp; |
| 555 | m = *mp; |
| 556 | *mp = NULL; |
| 557 | |
| 558 | tcpstat.tcps_rcvtotal++; |
| 559 | |
| 560 | if (m->m_pkthdr.fw_flags & IPFORWARD_MBUF_TAGGED) { |
| 561 | struct m_tag *mtag; |
| 562 | |
| 563 | mtag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL); |
| 564 | KKASSERT(mtag != NULL); |
| 565 | next_hop = m_tag_data(mtag); |
| 566 | } |
| 567 | |
| 568 | #ifdef INET6 |
| 569 | isipv6 = (mtod(m, struct ip *)->ip_v == 6) ? TRUE : FALSE; |
| 570 | #endif |
| 571 | |
| 572 | if (isipv6) { |
| 573 | /* IP6_EXTHDR_CHECK() is already done at tcp6_input() */ |
| 574 | ip6 = mtod(m, struct ip6_hdr *); |
| 575 | tlen = (sizeof *ip6) + ntohs(ip6->ip6_plen) - off0; |
| 576 | if (in6_cksum(m, IPPROTO_TCP, off0, tlen)) { |
| 577 | tcpstat.tcps_rcvbadsum++; |
| 578 | goto drop; |
| 579 | } |
| 580 | th = (struct tcphdr *)((caddr_t)ip6 + off0); |
| 581 | |
| 582 | /* |
| 583 | * Be proactive about unspecified IPv6 address in source. |
| 584 | * As we use all-zero to indicate unbounded/unconnected pcb, |
| 585 | * unspecified IPv6 address can be used to confuse us. |
| 586 | * |
| 587 | * Note that packets with unspecified IPv6 destination is |
| 588 | * already dropped in ip6_input. |
| 589 | */ |
| 590 | if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) { |
| 591 | /* XXX stat */ |
| 592 | goto drop; |
| 593 | } |
| 594 | } else { |
| 595 | /* |
| 596 | * Get IP and TCP header together in first mbuf. |
| 597 | * Note: IP leaves IP header in first mbuf. |
| 598 | */ |
| 599 | if (off0 > sizeof(struct ip)) { |
| 600 | ip_stripoptions(m); |
| 601 | off0 = sizeof(struct ip); |
| 602 | } |
| 603 | /* already checked and pulled up in ip_demux() */ |
| 604 | KASSERT(m->m_len >= sizeof(struct tcpiphdr), |
| 605 | ("TCP header not in one mbuf: m->m_len %d", m->m_len)); |
| 606 | ip = mtod(m, struct ip *); |
| 607 | ipov = (struct ipovly *)ip; |
| 608 | th = (struct tcphdr *)((caddr_t)ip + off0); |
| 609 | tlen = ip->ip_len; |
| 610 | |
| 611 | if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) { |
| 612 | if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR) |
| 613 | th->th_sum = m->m_pkthdr.csum_data; |
| 614 | else |
| 615 | th->th_sum = in_pseudo(ip->ip_src.s_addr, |
| 616 | ip->ip_dst.s_addr, |
| 617 | htonl(m->m_pkthdr.csum_data + |
| 618 | ip->ip_len + |
| 619 | IPPROTO_TCP)); |
| 620 | th->th_sum ^= 0xffff; |
| 621 | } else { |
| 622 | /* |
| 623 | * Checksum extended TCP header and data. |
| 624 | */ |
| 625 | len = sizeof(struct ip) + tlen; |
| 626 | bzero(ipov->ih_x1, sizeof ipov->ih_x1); |
| 627 | ipov->ih_len = (u_short)tlen; |
| 628 | ipov->ih_len = htons(ipov->ih_len); |
| 629 | th->th_sum = in_cksum(m, len); |
| 630 | } |
| 631 | if (th->th_sum) { |
| 632 | tcpstat.tcps_rcvbadsum++; |
| 633 | goto drop; |
| 634 | } |
| 635 | #ifdef INET6 |
| 636 | /* Re-initialization for later version check */ |
| 637 | ip->ip_v = IPVERSION; |
| 638 | #endif |
| 639 | } |
| 640 | |
| 641 | /* |
| 642 | * Check that TCP offset makes sense, |
| 643 | * pull out TCP options and adjust length. XXX |
| 644 | */ |
| 645 | off = th->th_off << 2; |
| 646 | /* already checked and pulled up in ip_demux() */ |
| 647 | KASSERT(off >= sizeof(struct tcphdr) && off <= tlen, |
| 648 | ("bad TCP data offset %d (tlen %d)", off, tlen)); |
| 649 | tlen -= off; /* tlen is used instead of ti->ti_len */ |
| 650 | if (off > sizeof(struct tcphdr)) { |
| 651 | if (isipv6) { |
| 652 | IP6_EXTHDR_CHECK(m, off0, off, IPPROTO_DONE); |
| 653 | ip6 = mtod(m, struct ip6_hdr *); |
| 654 | th = (struct tcphdr *)((caddr_t)ip6 + off0); |
| 655 | } else { |
| 656 | /* already pulled up in ip_demux() */ |
| 657 | KASSERT(m->m_len >= sizeof(struct ip) + off, |
| 658 | ("TCP header and options not in one mbuf: " |
| 659 | "m_len %d, off %d", m->m_len, off)); |
| 660 | } |
| 661 | optlen = off - sizeof(struct tcphdr); |
| 662 | optp = (u_char *)(th + 1); |
| 663 | } |
| 664 | thflags = th->th_flags; |
| 665 | |
| 666 | #ifdef TCP_DROP_SYNFIN |
| 667 | /* |
| 668 | * If the drop_synfin option is enabled, drop all packets with |
| 669 | * both the SYN and FIN bits set. This prevents e.g. nmap from |
| 670 | * identifying the TCP/IP stack. |
| 671 | * |
| 672 | * This is a violation of the TCP specification. |
| 673 | */ |
| 674 | if (drop_synfin && (thflags & (TH_SYN | TH_FIN)) == (TH_SYN | TH_FIN)) |
| 675 | goto drop; |
| 676 | #endif |
| 677 | |
| 678 | /* |
| 679 | * Convert TCP protocol specific fields to host format. |
| 680 | */ |
| 681 | th->th_seq = ntohl(th->th_seq); |
| 682 | th->th_ack = ntohl(th->th_ack); |
| 683 | th->th_win = ntohs(th->th_win); |
| 684 | th->th_urp = ntohs(th->th_urp); |
| 685 | |
| 686 | /* |
| 687 | * Delay dropping TCP, IP headers, IPv6 ext headers, and TCP options, |
| 688 | * until after ip6_savecontrol() is called and before other functions |
| 689 | * which don't want those proto headers. |
| 690 | * Because ip6_savecontrol() is going to parse the mbuf to |
| 691 | * search for data to be passed up to user-land, it wants mbuf |
| 692 | * parameters to be unchanged. |
| 693 | * XXX: the call of ip6_savecontrol() has been obsoleted based on |
| 694 | * latest version of the advanced API (20020110). |
| 695 | */ |
| 696 | drop_hdrlen = off0 + off; |
| 697 | |
| 698 | /* |
| 699 | * Locate pcb for segment. |
| 700 | */ |
| 701 | findpcb: |
| 702 | /* IPFIREWALL_FORWARD section */ |
| 703 | if (next_hop != NULL && !isipv6) { /* IPv6 support is not there yet */ |
| 704 | /* |
| 705 | * Transparently forwarded. Pretend to be the destination. |
| 706 | * already got one like this? |
| 707 | */ |
| 708 | cpu = mycpu->gd_cpuid; |
| 709 | inp = in_pcblookup_hash(&tcbinfo[cpu], |
| 710 | ip->ip_src, th->th_sport, |
| 711 | ip->ip_dst, th->th_dport, |
| 712 | 0, m->m_pkthdr.rcvif); |
| 713 | if (!inp) { |
| 714 | /* |
| 715 | * It's new. Try to find the ambushing socket. |
| 716 | */ |
| 717 | |
| 718 | /* |
| 719 | * The rest of the ipfw code stores the port in |
| 720 | * host order. XXX |
| 721 | * (The IP address is still in network order.) |
| 722 | */ |
| 723 | in_port_t dport = next_hop->sin_port ? |
| 724 | htons(next_hop->sin_port) : |
| 725 | th->th_dport; |
| 726 | |
| 727 | cpu = tcp_addrcpu(ip->ip_src.s_addr, th->th_sport, |
| 728 | next_hop->sin_addr.s_addr, dport); |
| 729 | inp = in_pcblookup_hash(&tcbinfo[cpu], |
| 730 | ip->ip_src, th->th_sport, |
| 731 | next_hop->sin_addr, dport, |
| 732 | 1, m->m_pkthdr.rcvif); |
| 733 | } |
| 734 | } else { |
| 735 | if (isipv6) { |
| 736 | inp = in6_pcblookup_hash(&tcbinfo[0], |
| 737 | &ip6->ip6_src, th->th_sport, |
| 738 | &ip6->ip6_dst, th->th_dport, |
| 739 | 1, m->m_pkthdr.rcvif); |
| 740 | } else { |
| 741 | cpu = mycpu->gd_cpuid; |
| 742 | inp = in_pcblookup_hash(&tcbinfo[cpu], |
| 743 | ip->ip_src, th->th_sport, |
| 744 | ip->ip_dst, th->th_dport, |
| 745 | 1, m->m_pkthdr.rcvif); |
| 746 | } |
| 747 | } |
| 748 | |
| 749 | /* |
| 750 | * If the state is CLOSED (i.e., TCB does not exist) then |
| 751 | * all data in the incoming segment is discarded. |
| 752 | * If the TCB exists but is in CLOSED state, it is embryonic, |
| 753 | * but should either do a listen or a connect soon. |
| 754 | */ |
| 755 | if (inp == NULL) { |
| 756 | if (log_in_vain) { |
| 757 | #ifdef INET6 |
| 758 | char dbuf[INET6_ADDRSTRLEN+2], sbuf[INET6_ADDRSTRLEN+2]; |
| 759 | #else |
| 760 | char dbuf[sizeof "aaa.bbb.ccc.ddd"]; |
| 761 | char sbuf[sizeof "aaa.bbb.ccc.ddd"]; |
| 762 | #endif |
| 763 | if (isipv6) { |
| 764 | strcpy(dbuf, "["); |
| 765 | strcat(dbuf, ip6_sprintf(&ip6->ip6_dst)); |
| 766 | strcat(dbuf, "]"); |
| 767 | strcpy(sbuf, "["); |
| 768 | strcat(sbuf, ip6_sprintf(&ip6->ip6_src)); |
| 769 | strcat(sbuf, "]"); |
| 770 | } else { |
| 771 | strcpy(dbuf, inet_ntoa(ip->ip_dst)); |
| 772 | strcpy(sbuf, inet_ntoa(ip->ip_src)); |
| 773 | } |
| 774 | switch (log_in_vain) { |
| 775 | case 1: |
| 776 | if (!(thflags & TH_SYN)) |
| 777 | break; |
| 778 | case 2: |
| 779 | log(LOG_INFO, |
| 780 | "Connection attempt to TCP %s:%d " |
| 781 | "from %s:%d flags:0x%02x\n", |
| 782 | dbuf, ntohs(th->th_dport), sbuf, |
| 783 | ntohs(th->th_sport), thflags); |
| 784 | break; |
| 785 | default: |
| 786 | break; |
| 787 | } |
| 788 | } |
| 789 | if (blackhole) { |
| 790 | switch (blackhole) { |
| 791 | case 1: |
| 792 | if (thflags & TH_SYN) |
| 793 | goto drop; |
| 794 | break; |
| 795 | case 2: |
| 796 | goto drop; |
| 797 | default: |
| 798 | goto drop; |
| 799 | } |
| 800 | } |
| 801 | rstreason = BANDLIM_RST_CLOSEDPORT; |
| 802 | goto dropwithreset; |
| 803 | } |
| 804 | |
| 805 | #ifdef IPSEC |
| 806 | if (isipv6) { |
| 807 | if (ipsec6_in_reject_so(m, inp->inp_socket)) { |
| 808 | ipsec6stat.in_polvio++; |
| 809 | goto drop; |
| 810 | } |
| 811 | } else { |
| 812 | if (ipsec4_in_reject_so(m, inp->inp_socket)) { |
| 813 | ipsecstat.in_polvio++; |
| 814 | goto drop; |
| 815 | } |
| 816 | } |
| 817 | #endif |
| 818 | #ifdef FAST_IPSEC |
| 819 | if (isipv6) { |
| 820 | if (ipsec6_in_reject(m, inp)) |
| 821 | goto drop; |
| 822 | } else { |
| 823 | if (ipsec4_in_reject(m, inp)) |
| 824 | goto drop; |
| 825 | } |
| 826 | #endif |
| 827 | /* Check the minimum TTL for socket. */ |
| 828 | #ifdef INET6 |
| 829 | if ((isipv6 ? ip6->ip6_hlim : ip->ip_ttl) < inp->inp_ip_minttl) |
| 830 | goto drop; |
| 831 | #endif |
| 832 | |
| 833 | tp = intotcpcb(inp); |
| 834 | if (tp == NULL) { |
| 835 | rstreason = BANDLIM_RST_CLOSEDPORT; |
| 836 | goto dropwithreset; |
| 837 | } |
| 838 | if (tp->t_state <= TCPS_CLOSED) |
| 839 | goto drop; |
| 840 | |
| 841 | /* Unscale the window into a 32-bit value. */ |
| 842 | if (!(thflags & TH_SYN)) |
| 843 | tiwin = th->th_win << tp->snd_scale; |
| 844 | else |
| 845 | tiwin = th->th_win; |
| 846 | |
| 847 | so = inp->inp_socket; |
| 848 | |
| 849 | #ifdef TCPDEBUG |
| 850 | if (so->so_options & SO_DEBUG) { |
| 851 | ostate = tp->t_state; |
| 852 | if (isipv6) |
| 853 | bcopy(ip6, tcp_saveipgen, sizeof(*ip6)); |
| 854 | else |
| 855 | bcopy(ip, tcp_saveipgen, sizeof(*ip)); |
| 856 | tcp_savetcp = *th; |
| 857 | } |
| 858 | #endif |
| 859 | |
| 860 | bzero(&to, sizeof to); |
| 861 | |
| 862 | if (so->so_options & SO_ACCEPTCONN) { |
| 863 | struct in_conninfo inc; |
| 864 | |
| 865 | #ifdef INET6 |
| 866 | inc.inc_isipv6 = (isipv6 == TRUE); |
| 867 | #endif |
| 868 | if (isipv6) { |
| 869 | inc.inc6_faddr = ip6->ip6_src; |
| 870 | inc.inc6_laddr = ip6->ip6_dst; |
| 871 | inc.inc6_route.ro_rt = NULL; /* XXX */ |
| 872 | } else { |
| 873 | inc.inc_faddr = ip->ip_src; |
| 874 | inc.inc_laddr = ip->ip_dst; |
| 875 | inc.inc_route.ro_rt = NULL; /* XXX */ |
| 876 | } |
| 877 | inc.inc_fport = th->th_sport; |
| 878 | inc.inc_lport = th->th_dport; |
| 879 | |
| 880 | /* |
| 881 | * If the state is LISTEN then ignore segment if it contains |
| 882 | * a RST. If the segment contains an ACK then it is bad and |
| 883 | * send a RST. If it does not contain a SYN then it is not |
| 884 | * interesting; drop it. |
| 885 | * |
| 886 | * If the state is SYN_RECEIVED (syncache) and seg contains |
| 887 | * an ACK, but not for our SYN/ACK, send a RST. If the seg |
| 888 | * contains a RST, check the sequence number to see if it |
| 889 | * is a valid reset segment. |
| 890 | */ |
| 891 | if ((thflags & (TH_RST | TH_ACK | TH_SYN)) != TH_SYN) { |
| 892 | if ((thflags & (TH_RST | TH_ACK | TH_SYN)) == TH_ACK) { |
| 893 | if (!syncache_expand(&inc, th, &so, m)) { |
| 894 | /* |
| 895 | * No syncache entry, or ACK was not |
| 896 | * for our SYN/ACK. Send a RST. |
| 897 | */ |
| 898 | tcpstat.tcps_badsyn++; |
| 899 | rstreason = BANDLIM_RST_OPENPORT; |
| 900 | goto dropwithreset; |
| 901 | } |
| 902 | |
| 903 | /* |
| 904 | * Could not complete 3-way handshake, |
| 905 | * connection is being closed down, and |
| 906 | * syncache will free mbuf. |
| 907 | */ |
| 908 | if (so == NULL) |
| 909 | return(IPPROTO_DONE); |
| 910 | |
| 911 | /* |
| 912 | * We must be in the correct protocol thread |
| 913 | * for this connection. |
| 914 | */ |
| 915 | KKASSERT(so->so_port == &curthread->td_msgport); |
| 916 | |
| 917 | /* |
| 918 | * Socket is created in state SYN_RECEIVED. |
| 919 | * Continue processing segment. |
| 920 | */ |
| 921 | inp = so->so_pcb; |
| 922 | tp = intotcpcb(inp); |
| 923 | /* |
| 924 | * This is what would have happened in |
| 925 | * tcp_output() when the SYN,ACK was sent. |
| 926 | */ |
| 927 | tp->snd_up = tp->snd_una; |
| 928 | tp->snd_max = tp->snd_nxt = tp->iss + 1; |
| 929 | tp->last_ack_sent = tp->rcv_nxt; |
| 930 | /* |
| 931 | * XXX possible bug - it doesn't appear that tp->snd_wnd is unscaled |
| 932 | * until the _second_ ACK is received: |
| 933 | * rcv SYN (set wscale opts) --> send SYN/ACK, set snd_wnd = window. |
| 934 | * rcv ACK, calculate tiwin --> process SYN_RECEIVED, determine wscale, |
| 935 | * move to ESTAB, set snd_wnd to tiwin. |
| 936 | */ |
| 937 | tp->snd_wnd = tiwin; /* unscaled */ |
| 938 | goto after_listen; |
| 939 | } |
| 940 | if (thflags & TH_RST) { |
| 941 | syncache_chkrst(&inc, th); |
| 942 | goto drop; |
| 943 | } |
| 944 | if (thflags & TH_ACK) { |
| 945 | syncache_badack(&inc); |
| 946 | tcpstat.tcps_badsyn++; |
| 947 | rstreason = BANDLIM_RST_OPENPORT; |
| 948 | goto dropwithreset; |
| 949 | } |
| 950 | goto drop; |
| 951 | } |
| 952 | |
| 953 | /* |
| 954 | * Segment's flags are (SYN) or (SYN | FIN). |
| 955 | */ |
| 956 | #ifdef INET6 |
| 957 | /* |
| 958 | * If deprecated address is forbidden, |
| 959 | * we do not accept SYN to deprecated interface |
| 960 | * address to prevent any new inbound connection from |
| 961 | * getting established. |
| 962 | * When we do not accept SYN, we send a TCP RST, |
| 963 | * with deprecated source address (instead of dropping |
| 964 | * it). We compromise it as it is much better for peer |
| 965 | * to send a RST, and RST will be the final packet |
| 966 | * for the exchange. |
| 967 | * |
| 968 | * If we do not forbid deprecated addresses, we accept |
| 969 | * the SYN packet. RFC2462 does not suggest dropping |
| 970 | * SYN in this case. |
| 971 | * If we decipher RFC2462 5.5.4, it says like this: |
| 972 | * 1. use of deprecated addr with existing |
| 973 | * communication is okay - "SHOULD continue to be |
| 974 | * used" |
| 975 | * 2. use of it with new communication: |
| 976 | * (2a) "SHOULD NOT be used if alternate address |
| 977 | * with sufficient scope is available" |
| 978 | * (2b) nothing mentioned otherwise. |
| 979 | * Here we fall into (2b) case as we have no choice in |
| 980 | * our source address selection - we must obey the peer. |
| 981 | * |
| 982 | * The wording in RFC2462 is confusing, and there are |
| 983 | * multiple description text for deprecated address |
| 984 | * handling - worse, they are not exactly the same. |
| 985 | * I believe 5.5.4 is the best one, so we follow 5.5.4. |
| 986 | */ |
| 987 | if (isipv6 && !ip6_use_deprecated) { |
| 988 | struct in6_ifaddr *ia6; |
| 989 | |
| 990 | if ((ia6 = ip6_getdstifaddr(m)) && |
| 991 | (ia6->ia6_flags & IN6_IFF_DEPRECATED)) { |
| 992 | tp = NULL; |
| 993 | rstreason = BANDLIM_RST_OPENPORT; |
| 994 | goto dropwithreset; |
| 995 | } |
| 996 | } |
| 997 | #endif |
| 998 | /* |
| 999 | * If it is from this socket, drop it, it must be forged. |
| 1000 | * Don't bother responding if the destination was a broadcast. |
| 1001 | */ |
| 1002 | if (th->th_dport == th->th_sport) { |
| 1003 | if (isipv6) { |
| 1004 | if (IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst, |
| 1005 | &ip6->ip6_src)) |
| 1006 | goto drop; |
| 1007 | } else { |
| 1008 | if (ip->ip_dst.s_addr == ip->ip_src.s_addr) |
| 1009 | goto drop; |
| 1010 | } |
| 1011 | } |
| 1012 | /* |
| 1013 | * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN |
| 1014 | * |
| 1015 | * Note that it is quite possible to receive unicast |
| 1016 | * link-layer packets with a broadcast IP address. Use |
| 1017 | * in_broadcast() to find them. |
| 1018 | */ |
| 1019 | if (m->m_flags & (M_BCAST | M_MCAST)) |
| 1020 | goto drop; |
| 1021 | if (isipv6) { |
| 1022 | if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || |
| 1023 | IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) |
| 1024 | goto drop; |
| 1025 | } else { |
| 1026 | if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || |
| 1027 | IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || |
| 1028 | ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || |
| 1029 | in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) |
| 1030 | goto drop; |
| 1031 | } |
| 1032 | /* |
| 1033 | * SYN appears to be valid; create compressed TCP state |
| 1034 | * for syncache, or perform t/tcp connection. |
| 1035 | */ |
| 1036 | if (so->so_qlen <= so->so_qlimit) { |
| 1037 | tcp_dooptions(&to, optp, optlen, TRUE); |
| 1038 | if (!syncache_add(&inc, &to, th, &so, m)) |
| 1039 | goto drop; |
| 1040 | |
| 1041 | /* |
| 1042 | * Entry added to syncache, mbuf used to |
| 1043 | * send SYN,ACK packet. |
| 1044 | */ |
| 1045 | if (so == NULL) |
| 1046 | return(IPPROTO_DONE); |
| 1047 | |
| 1048 | /* |
| 1049 | * We must be in the correct protocol thread for |
| 1050 | * this connection. |
| 1051 | */ |
| 1052 | KKASSERT(so->so_port == &curthread->td_msgport); |
| 1053 | |
| 1054 | inp = so->so_pcb; |
| 1055 | tp = intotcpcb(inp); |
| 1056 | tp->snd_wnd = tiwin; |
| 1057 | tp->t_starttime = ticks; |
| 1058 | tp->t_state = TCPS_ESTABLISHED; |
| 1059 | |
| 1060 | /* |
| 1061 | * If there is a FIN, or if there is data and the |
| 1062 | * connection is local, then delay SYN,ACK(SYN) in |
| 1063 | * the hope of piggy-backing it on a response |
| 1064 | * segment. Otherwise must send ACK now in case |
| 1065 | * the other side is slow starting. |
| 1066 | */ |
| 1067 | if (DELAY_ACK(tp) && |
| 1068 | ((thflags & TH_FIN) || |
| 1069 | (tlen != 0 && |
| 1070 | ((isipv6 && in6_localaddr(&inp->in6p_faddr)) || |
| 1071 | (!isipv6 && in_localaddr(inp->inp_faddr)))))) { |
| 1072 | tcp_callout_reset(tp, tp->tt_delack, |
| 1073 | tcp_delacktime, tcp_timer_delack); |
| 1074 | tp->t_flags |= TF_NEEDSYN; |
| 1075 | } else { |
| 1076 | tp->t_flags |= (TF_ACKNOW | TF_NEEDSYN); |
| 1077 | } |
| 1078 | |
| 1079 | tcpstat.tcps_connects++; |
| 1080 | soisconnected(so); |
| 1081 | goto trimthenstep6; |
| 1082 | } |
| 1083 | goto drop; |
| 1084 | } |
| 1085 | |
| 1086 | after_listen: |
| 1087 | /* |
| 1088 | * Should not happen - syncache should pick up these connections. |
| 1089 | * |
| 1090 | * Once we are past handling listen sockets we must be in the |
| 1091 | * correct protocol processing thread. |
| 1092 | */ |
| 1093 | KASSERT(tp->t_state != TCPS_LISTEN, ("tcp_input: TCPS_LISTEN state")); |
| 1094 | KKASSERT(so->so_port == &curthread->td_msgport); |
| 1095 | |
| 1096 | /* |
| 1097 | * This is the second part of the MSS DoS prevention code (after |
| 1098 | * minmss on the sending side) and it deals with too many too small |
| 1099 | * tcp packets in a too short timeframe (1 second). |
| 1100 | * |
| 1101 | * XXX Removed. This code was crap. It does not scale to network |
| 1102 | * speed, and default values break NFS. Gone. |
| 1103 | */ |
| 1104 | /* REMOVED */ |
| 1105 | |
| 1106 | /* |
| 1107 | * Segment received on connection. |
| 1108 | * |
| 1109 | * Reset idle time and keep-alive timer. Don't waste time if less |
| 1110 | * then a second has elapsed. Only update t_rcvtime for non-SYN |
| 1111 | * packets. |
| 1112 | * |
| 1113 | * Handle the case where one side thinks the connection is established |
| 1114 | * but the other side has, say, rebooted without cleaning out the |
| 1115 | * connection. The SYNs could be construed as an attack and wind |
| 1116 | * up ignored, but in case it isn't an attack we can validate the |
| 1117 | * connection by forcing a keepalive. |
| 1118 | */ |
| 1119 | if (TCPS_HAVEESTABLISHED(tp->t_state) && (ticks - tp->t_rcvtime) > hz) { |
| 1120 | if ((thflags & (TH_SYN | TH_ACK)) == TH_SYN) { |
| 1121 | tp->t_flags |= TF_KEEPALIVE; |
| 1122 | tcp_callout_reset(tp, tp->tt_keep, hz / 2, |
| 1123 | tcp_timer_keep); |
| 1124 | } else { |
| 1125 | tp->t_rcvtime = ticks; |
| 1126 | tp->t_flags &= ~TF_KEEPALIVE; |
| 1127 | tcp_callout_reset(tp, tp->tt_keep, |
| 1128 | tcp_getkeepidle(tp), |
| 1129 | tcp_timer_keep); |
| 1130 | } |
| 1131 | } |
| 1132 | |
| 1133 | /* |
| 1134 | * Process options. |
| 1135 | * XXX this is tradtitional behavior, may need to be cleaned up. |
| 1136 | */ |
| 1137 | tcp_dooptions(&to, optp, optlen, (thflags & TH_SYN) != 0); |
| 1138 | if (tp->t_state == TCPS_SYN_SENT && (thflags & TH_SYN)) { |
| 1139 | if (to.to_flags & TOF_SCALE) { |
| 1140 | tp->t_flags |= TF_RCVD_SCALE; |
| 1141 | tp->requested_s_scale = to.to_requested_s_scale; |
| 1142 | } |
| 1143 | if (to.to_flags & TOF_TS) { |
| 1144 | tp->t_flags |= TF_RCVD_TSTMP; |
| 1145 | tp->ts_recent = to.to_tsval; |
| 1146 | tp->ts_recent_age = ticks; |
| 1147 | } |
| 1148 | if (to.to_flags & TOF_MSS) |
| 1149 | tcp_mss(tp, to.to_mss); |
| 1150 | /* |
| 1151 | * Only set the TF_SACK_PERMITTED per-connection flag |
| 1152 | * if we got a SACK_PERMITTED option from the other side |
| 1153 | * and the global tcp_do_sack variable is true. |
| 1154 | */ |
| 1155 | if (tcp_do_sack && (to.to_flags & TOF_SACK_PERMITTED)) |
| 1156 | tp->t_flags |= TF_SACK_PERMITTED; |
| 1157 | } |
| 1158 | |
| 1159 | /* |
| 1160 | * Header prediction: check for the two common cases |
| 1161 | * of a uni-directional data xfer. If the packet has |
| 1162 | * no control flags, is in-sequence, the window didn't |
| 1163 | * change and we're not retransmitting, it's a |
| 1164 | * candidate. If the length is zero and the ack moved |
| 1165 | * forward, we're the sender side of the xfer. Just |
| 1166 | * free the data acked & wake any higher level process |
| 1167 | * that was blocked waiting for space. If the length |
| 1168 | * is non-zero and the ack didn't move, we're the |
| 1169 | * receiver side. If we're getting packets in-order |
| 1170 | * (the reassembly queue is empty), add the data to |
| 1171 | * the socket buffer and note that we need a delayed ack. |
| 1172 | * Make sure that the hidden state-flags are also off. |
| 1173 | * Since we check for TCPS_ESTABLISHED above, it can only |
| 1174 | * be TH_NEEDSYN. |
| 1175 | */ |
| 1176 | if (tp->t_state == TCPS_ESTABLISHED && |
| 1177 | (thflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK && |
| 1178 | !(tp->t_flags & (TF_NEEDSYN | TF_NEEDFIN)) && |
| 1179 | (!(to.to_flags & TOF_TS) || |
| 1180 | TSTMP_GEQ(to.to_tsval, tp->ts_recent)) && |
| 1181 | th->th_seq == tp->rcv_nxt && |
| 1182 | tp->snd_nxt == tp->snd_max) { |
| 1183 | |
| 1184 | /* |
| 1185 | * If last ACK falls within this segment's sequence numbers, |
| 1186 | * record the timestamp. |
| 1187 | * NOTE that the test is modified according to the latest |
| 1188 | * proposal of the tcplw@cray.com list (Braden 1993/04/26). |
| 1189 | */ |
| 1190 | if ((to.to_flags & TOF_TS) && |
| 1191 | SEQ_LEQ(th->th_seq, tp->last_ack_sent)) { |
| 1192 | tp->ts_recent_age = ticks; |
| 1193 | tp->ts_recent = to.to_tsval; |
| 1194 | } |
| 1195 | |
| 1196 | if (tlen == 0) { |
| 1197 | if (SEQ_GT(th->th_ack, tp->snd_una) && |
| 1198 | SEQ_LEQ(th->th_ack, tp->snd_max) && |
| 1199 | tp->snd_cwnd >= tp->snd_wnd && |
| 1200 | !IN_FASTRECOVERY(tp)) { |
| 1201 | /* |
| 1202 | * This is a pure ack for outstanding data. |
| 1203 | */ |
| 1204 | ++tcpstat.tcps_predack; |
| 1205 | /* |
| 1206 | * "bad retransmit" recovery |
| 1207 | * |
| 1208 | * If Eifel detection applies, then |
| 1209 | * it is deterministic, so use it |
| 1210 | * unconditionally over the old heuristic. |
| 1211 | * Otherwise, fall back to the old heuristic. |
| 1212 | */ |
| 1213 | if (tcp_do_eifel_detect && |
| 1214 | (to.to_flags & TOF_TS) && to.to_tsecr && |
| 1215 | (tp->t_flags & TF_FIRSTACCACK)) { |
| 1216 | /* Eifel detection applicable. */ |
| 1217 | if (to.to_tsecr < tp->t_rexmtTS) { |
| 1218 | tcp_revert_congestion_state(tp); |
| 1219 | ++tcpstat.tcps_eifeldetected; |
| 1220 | } |
| 1221 | } else if (tp->t_rxtshift == 1 && |
| 1222 | ticks < tp->t_badrxtwin) { |
| 1223 | tcp_revert_congestion_state(tp); |
| 1224 | ++tcpstat.tcps_rttdetected; |
| 1225 | } |
| 1226 | tp->t_flags &= ~(TF_FIRSTACCACK | |
| 1227 | TF_FASTREXMT | TF_EARLYREXMT); |
| 1228 | /* |
| 1229 | * Recalculate the retransmit timer / rtt. |
| 1230 | * |
| 1231 | * Some machines (certain windows boxes) |
| 1232 | * send broken timestamp replies during the |
| 1233 | * SYN+ACK phase, ignore timestamps of 0. |
| 1234 | */ |
| 1235 | if ((to.to_flags & TOF_TS) && to.to_tsecr) { |
| 1236 | tcp_xmit_timer(tp, |
| 1237 | ticks - to.to_tsecr + 1); |
| 1238 | } else if (tp->t_rtttime && |
| 1239 | SEQ_GT(th->th_ack, tp->t_rtseq)) { |
| 1240 | tcp_xmit_timer(tp, |
| 1241 | ticks - tp->t_rtttime); |
| 1242 | } |
| 1243 | tcp_xmit_bandwidth_limit(tp, th->th_ack); |
| 1244 | acked = th->th_ack - tp->snd_una; |
| 1245 | tcpstat.tcps_rcvackpack++; |
| 1246 | tcpstat.tcps_rcvackbyte += acked; |
| 1247 | sbdrop(&so->so_snd.sb, acked); |
| 1248 | tp->snd_recover = th->th_ack - 1; |
| 1249 | tp->snd_una = th->th_ack; |
| 1250 | tp->t_dupacks = 0; |
| 1251 | /* |
| 1252 | * Update window information. |
| 1253 | */ |
| 1254 | if (tiwin != tp->snd_wnd && |
| 1255 | acceptable_window_update(tp, th, tiwin)) { |
| 1256 | /* keep track of pure window updates */ |
| 1257 | if (tp->snd_wl2 == th->th_ack && |
| 1258 | tiwin > tp->snd_wnd) |
| 1259 | tcpstat.tcps_rcvwinupd++; |
| 1260 | tp->snd_wnd = tiwin; |
| 1261 | tp->snd_wl1 = th->th_seq; |
| 1262 | tp->snd_wl2 = th->th_ack; |
| 1263 | if (tp->snd_wnd > tp->max_sndwnd) |
| 1264 | tp->max_sndwnd = tp->snd_wnd; |
| 1265 | } |
| 1266 | m_freem(m); |
| 1267 | ND6_HINT(tp); /* some progress has been done */ |
| 1268 | /* |
| 1269 | * If all outstanding data are acked, stop |
| 1270 | * retransmit timer, otherwise restart timer |
| 1271 | * using current (possibly backed-off) value. |
| 1272 | * If process is waiting for space, |
| 1273 | * wakeup/selwakeup/signal. If data |
| 1274 | * are ready to send, let tcp_output |
| 1275 | * decide between more output or persist. |
| 1276 | */ |
| 1277 | if (tp->snd_una == tp->snd_max) { |
| 1278 | tcp_callout_stop(tp, tp->tt_rexmt); |
| 1279 | } else if (!tcp_callout_active(tp, |
| 1280 | tp->tt_persist)) { |
| 1281 | tcp_callout_reset(tp, tp->tt_rexmt, |
| 1282 | tp->t_rxtcur, tcp_timer_rexmt); |
| 1283 | } |
| 1284 | sowwakeup(so); |
| 1285 | if (so->so_snd.ssb_cc > 0) |
| 1286 | tcp_output(tp); |
| 1287 | return(IPPROTO_DONE); |
| 1288 | } |
| 1289 | } else if (tiwin == tp->snd_wnd && |
| 1290 | th->th_ack == tp->snd_una && |
| 1291 | LIST_EMPTY(&tp->t_segq) && |
| 1292 | tlen <= ssb_space(&so->so_rcv)) { |
| 1293 | u_long newsize = 0; /* automatic sockbuf scaling */ |
| 1294 | /* |
| 1295 | * This is a pure, in-sequence data packet |
| 1296 | * with nothing on the reassembly queue and |
| 1297 | * we have enough buffer space to take it. |
| 1298 | */ |
| 1299 | ++tcpstat.tcps_preddat; |
| 1300 | tp->rcv_nxt += tlen; |
| 1301 | tcpstat.tcps_rcvpack++; |
| 1302 | tcpstat.tcps_rcvbyte += tlen; |
| 1303 | ND6_HINT(tp); /* some progress has been done */ |
| 1304 | /* |
| 1305 | * Automatic sizing of receive socket buffer. Often the send |
| 1306 | * buffer size is not optimally adjusted to the actual network |
| 1307 | * conditions at hand (delay bandwidth product). Setting the |
| 1308 | * buffer size too small limits throughput on links with high |
| 1309 | * bandwidth and high delay (eg. trans-continental/oceanic links). |
| 1310 | * |
| 1311 | * On the receive side the socket buffer memory is only rarely |
| 1312 | * used to any significant extent. This allows us to be much |
| 1313 | * more aggressive in scaling the receive socket buffer. For |
| 1314 | * the case that the buffer space is actually used to a large |
| 1315 | * extent and we run out of kernel memory we can simply drop |
| 1316 | * the new segments; TCP on the sender will just retransmit it |
| 1317 | * later. Setting the buffer size too big may only consume too |
| 1318 | * much kernel memory if the application doesn't read() from |
| 1319 | * the socket or packet loss or reordering makes use of the |
| 1320 | * reassembly queue. |
| 1321 | * |
| 1322 | * The criteria to step up the receive buffer one notch are: |
| 1323 | * 1. the number of bytes received during the time it takes |
| 1324 | * one timestamp to be reflected back to us (the RTT); |
| 1325 | * 2. received bytes per RTT is within seven eighth of the |
| 1326 | * current socket buffer size; |
| 1327 | * 3. receive buffer size has not hit maximal automatic size; |
| 1328 | * |
| 1329 | * This algorithm does one step per RTT at most and only if |
| 1330 | * we receive a bulk stream w/o packet losses or reorderings. |
| 1331 | * Shrinking the buffer during idle times is not necessary as |
| 1332 | * it doesn't consume any memory when idle. |
| 1333 | * |
| 1334 | * TODO: Only step up if the application is actually serving |
| 1335 | * the buffer to better manage the socket buffer resources. |
| 1336 | */ |
| 1337 | if (tcp_do_autorcvbuf && |
| 1338 | to.to_tsecr && |
| 1339 | (so->so_rcv.ssb_flags & SSB_AUTOSIZE)) { |
| 1340 | if (to.to_tsecr > tp->rfbuf_ts && |
| 1341 | to.to_tsecr - tp->rfbuf_ts < hz) { |
| 1342 | if (tp->rfbuf_cnt > |
| 1343 | (so->so_rcv.ssb_hiwat / 8 * 7) && |
| 1344 | so->so_rcv.ssb_hiwat < |
| 1345 | tcp_autorcvbuf_max) { |
| 1346 | newsize = |
| 1347 | ulmin(so->so_rcv.ssb_hiwat + |
| 1348 | tcp_autorcvbuf_inc, |
| 1349 | tcp_autorcvbuf_max); |
| 1350 | } |
| 1351 | /* Start over with next RTT. */ |
| 1352 | tp->rfbuf_ts = 0; |
| 1353 | tp->rfbuf_cnt = 0; |
| 1354 | } else |
| 1355 | tp->rfbuf_cnt += tlen; /* add up */ |
| 1356 | } |
| 1357 | /* |
| 1358 | * Add data to socket buffer. |
| 1359 | */ |
| 1360 | if (so->so_state & SS_CANTRCVMORE) { |
| 1361 | m_freem(m); |
| 1362 | } else { |
| 1363 | /* |
| 1364 | * Set new socket buffer size, give up when |
| 1365 | * limit is reached. |
| 1366 | * |
| 1367 | * Adjusting the size can mess up ACK |
| 1368 | * sequencing when pure window updates are |
| 1369 | * being avoided (which is the default), |
| 1370 | * so force an ack. |
| 1371 | */ |
| 1372 | lwkt_gettoken(&so->so_rcv.ssb_token); |
| 1373 | if (newsize) { |
| 1374 | tp->t_flags |= TF_RXRESIZED; |
| 1375 | if (!ssb_reserve(&so->so_rcv, newsize, |
| 1376 | so, NULL)) { |
| 1377 | atomic_clear_int(&so->so_rcv.ssb_flags, SSB_AUTOSIZE); |
| 1378 | } |
| 1379 | if (newsize >= |
| 1380 | (TCP_MAXWIN << tp->rcv_scale)) { |
| 1381 | atomic_clear_int(&so->so_rcv.ssb_flags, SSB_AUTOSIZE); |
| 1382 | } |
| 1383 | } |
| 1384 | m_adj(m, drop_hdrlen); /* delayed header drop */ |
| 1385 | ssb_appendstream(&so->so_rcv, m); |
| 1386 | lwkt_reltoken(&so->so_rcv.ssb_token); |
| 1387 | } |
| 1388 | sorwakeup(so); |
| 1389 | /* |
| 1390 | * This code is responsible for most of the ACKs |
| 1391 | * the TCP stack sends back after receiving a data |
| 1392 | * packet. Note that the DELAY_ACK check fails if |
| 1393 | * the delack timer is already running, which results |
| 1394 | * in an ack being sent every other packet (which is |
| 1395 | * what we want). |
| 1396 | * |
| 1397 | * We then further aggregate acks by not actually |
| 1398 | * sending one until the protocol thread has completed |
| 1399 | * processing the current backlog of packets. This |
| 1400 | * does not delay the ack any further, but allows us |
| 1401 | * to take advantage of the packet aggregation that |
| 1402 | * high speed NICs do (usually blocks of 8-10 packets) |
| 1403 | * to send a single ack rather then four or five acks, |
| 1404 | * greatly reducing the ack rate, the return channel |
| 1405 | * bandwidth, and the protocol overhead on both ends. |
| 1406 | * |
| 1407 | * Since this also has the effect of slowing down |
| 1408 | * the exponential slow-start ramp-up, systems with |
| 1409 | * very large bandwidth-delay products might want |
| 1410 | * to turn the feature off. |
| 1411 | */ |
| 1412 | if (DELAY_ACK(tp)) { |
| 1413 | tcp_callout_reset(tp, tp->tt_delack, |
| 1414 | tcp_delacktime, tcp_timer_delack); |
| 1415 | } else if (tcp_aggregate_acks) { |
| 1416 | tp->t_flags |= TF_ACKNOW; |
| 1417 | if (!(tp->t_flags & TF_ONOUTPUTQ)) { |
| 1418 | tp->t_flags |= TF_ONOUTPUTQ; |
| 1419 | tp->tt_cpu = mycpu->gd_cpuid; |
| 1420 | TAILQ_INSERT_TAIL( |
| 1421 | &tcpcbackq[tp->tt_cpu], |
| 1422 | tp, t_outputq); |
| 1423 | } |
| 1424 | } else { |
| 1425 | tp->t_flags |= TF_ACKNOW; |
| 1426 | tcp_output(tp); |
| 1427 | } |
| 1428 | return(IPPROTO_DONE); |
| 1429 | } |
| 1430 | } |
| 1431 | |
| 1432 | /* |
| 1433 | * Calculate amount of space in receive window, |
| 1434 | * and then do TCP input processing. |
| 1435 | * Receive window is amount of space in rcv queue, |
| 1436 | * but not less than advertised window. |
| 1437 | */ |
| 1438 | recvwin = ssb_space(&so->so_rcv); |
| 1439 | if (recvwin < 0) |
| 1440 | recvwin = 0; |
| 1441 | tp->rcv_wnd = imax(recvwin, (int)(tp->rcv_adv - tp->rcv_nxt)); |
| 1442 | |
| 1443 | /* Reset receive buffer auto scaling when not in bulk receive mode. */ |
| 1444 | tp->rfbuf_ts = 0; |
| 1445 | tp->rfbuf_cnt = 0; |
| 1446 | |
| 1447 | switch (tp->t_state) { |
| 1448 | /* |
| 1449 | * If the state is SYN_RECEIVED: |
| 1450 | * if seg contains an ACK, but not for our SYN/ACK, send a RST. |
| 1451 | */ |
| 1452 | case TCPS_SYN_RECEIVED: |
| 1453 | if ((thflags & TH_ACK) && |
| 1454 | (SEQ_LEQ(th->th_ack, tp->snd_una) || |
| 1455 | SEQ_GT(th->th_ack, tp->snd_max))) { |
| 1456 | rstreason = BANDLIM_RST_OPENPORT; |
| 1457 | goto dropwithreset; |
| 1458 | } |
| 1459 | break; |
| 1460 | |
| 1461 | /* |
| 1462 | * If the state is SYN_SENT: |
| 1463 | * if seg contains an ACK, but not for our SYN, drop the input. |
| 1464 | * if seg contains a RST, then drop the connection. |
| 1465 | * if seg does not contain SYN, then drop it. |
| 1466 | * Otherwise this is an acceptable SYN segment |
| 1467 | * initialize tp->rcv_nxt and tp->irs |
| 1468 | * if seg contains ack then advance tp->snd_una |
| 1469 | * if SYN has been acked change to ESTABLISHED else SYN_RCVD state |
| 1470 | * arrange for segment to be acked (eventually) |
| 1471 | * continue processing rest of data/controls, beginning with URG |
| 1472 | */ |
| 1473 | case TCPS_SYN_SENT: |
| 1474 | if ((thflags & TH_ACK) && |
| 1475 | (SEQ_LEQ(th->th_ack, tp->iss) || |
| 1476 | SEQ_GT(th->th_ack, tp->snd_max))) { |
| 1477 | rstreason = BANDLIM_UNLIMITED; |
| 1478 | goto dropwithreset; |
| 1479 | } |
| 1480 | if (thflags & TH_RST) { |
| 1481 | if (thflags & TH_ACK) |
| 1482 | tp = tcp_drop(tp, ECONNREFUSED); |
| 1483 | goto drop; |
| 1484 | } |
| 1485 | if (!(thflags & TH_SYN)) |
| 1486 | goto drop; |
| 1487 | tp->snd_wnd = th->th_win; /* initial send window */ |
| 1488 | |
| 1489 | tp->irs = th->th_seq; |
| 1490 | tcp_rcvseqinit(tp); |
| 1491 | if (thflags & TH_ACK) { |
| 1492 | /* Our SYN was acked. */ |
| 1493 | tcpstat.tcps_connects++; |
| 1494 | soisconnected(so); |
| 1495 | /* Do window scaling on this connection? */ |
| 1496 | if ((tp->t_flags & (TF_RCVD_SCALE | TF_REQ_SCALE)) == |
| 1497 | (TF_RCVD_SCALE | TF_REQ_SCALE)) { |
| 1498 | tp->snd_scale = tp->requested_s_scale; |
| 1499 | tp->rcv_scale = tp->request_r_scale; |
| 1500 | } |
| 1501 | tp->rcv_adv += tp->rcv_wnd; |
| 1502 | tp->snd_una++; /* SYN is acked */ |
| 1503 | tcp_callout_stop(tp, tp->tt_rexmt); |
| 1504 | /* |
| 1505 | * If there's data, delay ACK; if there's also a FIN |
| 1506 | * ACKNOW will be turned on later. |
| 1507 | */ |
| 1508 | if (DELAY_ACK(tp) && tlen != 0) { |
| 1509 | tcp_callout_reset(tp, tp->tt_delack, |
| 1510 | tcp_delacktime, tcp_timer_delack); |
| 1511 | } else { |
| 1512 | tp->t_flags |= TF_ACKNOW; |
| 1513 | } |
| 1514 | /* |
| 1515 | * Received <SYN,ACK> in SYN_SENT[*] state. |
| 1516 | * Transitions: |
| 1517 | * SYN_SENT --> ESTABLISHED |
| 1518 | * SYN_SENT* --> FIN_WAIT_1 |
| 1519 | */ |
| 1520 | tp->t_starttime = ticks; |
| 1521 | if (tp->t_flags & TF_NEEDFIN) { |
| 1522 | tp->t_state = TCPS_FIN_WAIT_1; |
| 1523 | tp->t_flags &= ~TF_NEEDFIN; |
| 1524 | thflags &= ~TH_SYN; |
| 1525 | } else { |
| 1526 | tp->t_state = TCPS_ESTABLISHED; |
| 1527 | tcp_callout_reset(tp, tp->tt_keep, |
| 1528 | tcp_getkeepidle(tp), |
| 1529 | tcp_timer_keep); |
| 1530 | } |
| 1531 | } else { |
| 1532 | /* |
| 1533 | * Received initial SYN in SYN-SENT[*] state => |
| 1534 | * simultaneous open. |
| 1535 | * Do 3-way handshake: |
| 1536 | * SYN-SENT -> SYN-RECEIVED |
| 1537 | * SYN-SENT* -> SYN-RECEIVED* |
| 1538 | */ |
| 1539 | tp->t_flags |= TF_ACKNOW; |
| 1540 | tcp_callout_stop(tp, tp->tt_rexmt); |
| 1541 | tp->t_state = TCPS_SYN_RECEIVED; |
| 1542 | } |
| 1543 | |
| 1544 | trimthenstep6: |
| 1545 | /* |
| 1546 | * Advance th->th_seq to correspond to first data byte. |
| 1547 | * If data, trim to stay within window, |
| 1548 | * dropping FIN if necessary. |
| 1549 | */ |
| 1550 | th->th_seq++; |
| 1551 | if (tlen > tp->rcv_wnd) { |
| 1552 | todrop = tlen - tp->rcv_wnd; |
| 1553 | m_adj(m, -todrop); |
| 1554 | tlen = tp->rcv_wnd; |
| 1555 | thflags &= ~TH_FIN; |
| 1556 | tcpstat.tcps_rcvpackafterwin++; |
| 1557 | tcpstat.tcps_rcvbyteafterwin += todrop; |
| 1558 | } |
| 1559 | tp->snd_wl1 = th->th_seq - 1; |
| 1560 | tp->rcv_up = th->th_seq; |
| 1561 | /* |
| 1562 | * Client side of transaction: already sent SYN and data. |
| 1563 | * If the remote host used T/TCP to validate the SYN, |
| 1564 | * our data will be ACK'd; if so, enter normal data segment |
| 1565 | * processing in the middle of step 5, ack processing. |
| 1566 | * Otherwise, goto step 6. |
| 1567 | */ |
| 1568 | if (thflags & TH_ACK) |
| 1569 | goto process_ACK; |
| 1570 | |
| 1571 | goto step6; |
| 1572 | |
| 1573 | /* |
| 1574 | * If the state is LAST_ACK or CLOSING or TIME_WAIT: |
| 1575 | * do normal processing (we no longer bother with T/TCP). |
| 1576 | */ |
| 1577 | case TCPS_LAST_ACK: |
| 1578 | case TCPS_CLOSING: |
| 1579 | case TCPS_TIME_WAIT: |
| 1580 | break; /* continue normal processing */ |
| 1581 | } |
| 1582 | |
| 1583 | /* |
| 1584 | * States other than LISTEN or SYN_SENT. |
| 1585 | * First check the RST flag and sequence number since reset segments |
| 1586 | * are exempt from the timestamp and connection count tests. This |
| 1587 | * fixes a bug introduced by the Stevens, vol. 2, p. 960 bugfix |
| 1588 | * below which allowed reset segments in half the sequence space |
| 1589 | * to fall though and be processed (which gives forged reset |
| 1590 | * segments with a random sequence number a 50 percent chance of |
| 1591 | * killing a connection). |
| 1592 | * Then check timestamp, if present. |
| 1593 | * Then check the connection count, if present. |
| 1594 | * Then check that at least some bytes of segment are within |
| 1595 | * receive window. If segment begins before rcv_nxt, |
| 1596 | * drop leading data (and SYN); if nothing left, just ack. |
| 1597 | * |
| 1598 | * |
| 1599 | * If the RST bit is set, check the sequence number to see |
| 1600 | * if this is a valid reset segment. |
| 1601 | * RFC 793 page 37: |
| 1602 | * In all states except SYN-SENT, all reset (RST) segments |
| 1603 | * are validated by checking their SEQ-fields. A reset is |
| 1604 | * valid if its sequence number is in the window. |
| 1605 | * Note: this does not take into account delayed ACKs, so |
| 1606 | * we should test against last_ack_sent instead of rcv_nxt. |
| 1607 | * The sequence number in the reset segment is normally an |
| 1608 | * echo of our outgoing acknowledgement numbers, but some hosts |
| 1609 | * send a reset with the sequence number at the rightmost edge |
| 1610 | * of our receive window, and we have to handle this case. |
| 1611 | * If we have multiple segments in flight, the intial reset |
| 1612 | * segment sequence numbers will be to the left of last_ack_sent, |
| 1613 | * but they will eventually catch up. |
| 1614 | * In any case, it never made sense to trim reset segments to |
| 1615 | * fit the receive window since RFC 1122 says: |
| 1616 | * 4.2.2.12 RST Segment: RFC-793 Section 3.4 |
| 1617 | * |
| 1618 | * A TCP SHOULD allow a received RST segment to include data. |
| 1619 | * |
| 1620 | * DISCUSSION |
| 1621 | * It has been suggested that a RST segment could contain |
| 1622 | * ASCII text that encoded and explained the cause of the |
| 1623 | * RST. No standard has yet been established for such |
| 1624 | * data. |
| 1625 | * |
| 1626 | * If the reset segment passes the sequence number test examine |
| 1627 | * the state: |
| 1628 | * SYN_RECEIVED STATE: |
| 1629 | * If passive open, return to LISTEN state. |
| 1630 | * If active open, inform user that connection was refused. |
| 1631 | * ESTABLISHED, FIN_WAIT_1, FIN_WAIT_2, CLOSE_WAIT STATES: |
| 1632 | * Inform user that connection was reset, and close tcb. |
| 1633 | * CLOSING, LAST_ACK STATES: |
| 1634 | * Close the tcb. |
| 1635 | * TIME_WAIT STATE: |
| 1636 | * Drop the segment - see Stevens, vol. 2, p. 964 and |
| 1637 | * RFC 1337. |
| 1638 | */ |
| 1639 | if (thflags & TH_RST) { |
| 1640 | if (SEQ_GEQ(th->th_seq, tp->last_ack_sent) && |
| 1641 | SEQ_LEQ(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) { |
| 1642 | switch (tp->t_state) { |
| 1643 | |
| 1644 | case TCPS_SYN_RECEIVED: |
| 1645 | so->so_error = ECONNREFUSED; |
| 1646 | goto close; |
| 1647 | |
| 1648 | case TCPS_ESTABLISHED: |
| 1649 | case TCPS_FIN_WAIT_1: |
| 1650 | case TCPS_FIN_WAIT_2: |
| 1651 | case TCPS_CLOSE_WAIT: |
| 1652 | so->so_error = ECONNRESET; |
| 1653 | close: |
| 1654 | tp->t_state = TCPS_CLOSED; |
| 1655 | tcpstat.tcps_drops++; |
| 1656 | tp = tcp_close(tp); |
| 1657 | break; |
| 1658 | |
| 1659 | case TCPS_CLOSING: |
| 1660 | case TCPS_LAST_ACK: |
| 1661 | tp = tcp_close(tp); |
| 1662 | break; |
| 1663 | |
| 1664 | case TCPS_TIME_WAIT: |
| 1665 | break; |
| 1666 | } |
| 1667 | } |
| 1668 | goto drop; |
| 1669 | } |
| 1670 | |
| 1671 | /* |
| 1672 | * RFC 1323 PAWS: If we have a timestamp reply on this segment |
| 1673 | * and it's less than ts_recent, drop it. |
| 1674 | */ |
| 1675 | if ((to.to_flags & TOF_TS) && tp->ts_recent != 0 && |
| 1676 | TSTMP_LT(to.to_tsval, tp->ts_recent)) { |
| 1677 | |
| 1678 | /* Check to see if ts_recent is over 24 days old. */ |
| 1679 | if ((int)(ticks - tp->ts_recent_age) > TCP_PAWS_IDLE) { |
| 1680 | /* |
| 1681 | * Invalidate ts_recent. If this segment updates |
| 1682 | * ts_recent, the age will be reset later and ts_recent |
| 1683 | * will get a valid value. If it does not, setting |
| 1684 | * ts_recent to zero will at least satisfy the |
| 1685 | * requirement that zero be placed in the timestamp |
| 1686 | * echo reply when ts_recent isn't valid. The |
| 1687 | * age isn't reset until we get a valid ts_recent |
| 1688 | * because we don't want out-of-order segments to be |
| 1689 | * dropped when ts_recent is old. |
| 1690 | */ |
| 1691 | tp->ts_recent = 0; |
| 1692 | } else { |
| 1693 | tcpstat.tcps_rcvduppack++; |
| 1694 | tcpstat.tcps_rcvdupbyte += tlen; |
| 1695 | tcpstat.tcps_pawsdrop++; |
| 1696 | if (tlen) |
| 1697 | goto dropafterack; |
| 1698 | goto drop; |
| 1699 | } |
| 1700 | } |
| 1701 | |
| 1702 | /* |
| 1703 | * In the SYN-RECEIVED state, validate that the packet belongs to |
| 1704 | * this connection before trimming the data to fit the receive |
| 1705 | * window. Check the sequence number versus IRS since we know |
| 1706 | * the sequence numbers haven't wrapped. This is a partial fix |
| 1707 | * for the "LAND" DoS attack. |
| 1708 | */ |
| 1709 | if (tp->t_state == TCPS_SYN_RECEIVED && SEQ_LT(th->th_seq, tp->irs)) { |
| 1710 | rstreason = BANDLIM_RST_OPENPORT; |
| 1711 | goto dropwithreset; |
| 1712 | } |
| 1713 | |
| 1714 | todrop = tp->rcv_nxt - th->th_seq; |
| 1715 | if (todrop > 0) { |
| 1716 | if (TCP_DO_SACK(tp)) { |
| 1717 | /* Report duplicate segment at head of packet. */ |
| 1718 | tp->reportblk.rblk_start = th->th_seq; |
| 1719 | tp->reportblk.rblk_end = th->th_seq + tlen; |
| 1720 | if (thflags & TH_FIN) |
| 1721 | ++tp->reportblk.rblk_end; |
| 1722 | if (SEQ_GT(tp->reportblk.rblk_end, tp->rcv_nxt)) |
| 1723 | tp->reportblk.rblk_end = tp->rcv_nxt; |
| 1724 | tp->t_flags |= (TF_DUPSEG | TF_SACKLEFT | TF_ACKNOW); |
| 1725 | } |
| 1726 | if (thflags & TH_SYN) { |
| 1727 | thflags &= ~TH_SYN; |
| 1728 | th->th_seq++; |
| 1729 | if (th->th_urp > 1) |
| 1730 | th->th_urp--; |
| 1731 | else |
| 1732 | thflags &= ~TH_URG; |
| 1733 | todrop--; |
| 1734 | } |
| 1735 | /* |
| 1736 | * Following if statement from Stevens, vol. 2, p. 960. |
| 1737 | */ |
| 1738 | if (todrop > tlen || |
| 1739 | (todrop == tlen && !(thflags & TH_FIN))) { |
| 1740 | /* |
| 1741 | * Any valid FIN must be to the left of the window. |
| 1742 | * At this point the FIN must be a duplicate or out |
| 1743 | * of sequence; drop it. |
| 1744 | */ |
| 1745 | thflags &= ~TH_FIN; |
| 1746 | |
| 1747 | /* |
| 1748 | * Send an ACK to resynchronize and drop any data. |
| 1749 | * But keep on processing for RST or ACK. |
| 1750 | */ |
| 1751 | tp->t_flags |= TF_ACKNOW; |
| 1752 | todrop = tlen; |
| 1753 | tcpstat.tcps_rcvduppack++; |
| 1754 | tcpstat.tcps_rcvdupbyte += todrop; |
| 1755 | } else { |
| 1756 | tcpstat.tcps_rcvpartduppack++; |
| 1757 | tcpstat.tcps_rcvpartdupbyte += todrop; |
| 1758 | } |
| 1759 | drop_hdrlen += todrop; /* drop from the top afterwards */ |
| 1760 | th->th_seq += todrop; |
| 1761 | tlen -= todrop; |
| 1762 | if (th->th_urp > todrop) |
| 1763 | th->th_urp -= todrop; |
| 1764 | else { |
| 1765 | thflags &= ~TH_URG; |
| 1766 | th->th_urp = 0; |
| 1767 | } |
| 1768 | } |
| 1769 | |
| 1770 | /* |
| 1771 | * If new data are received on a connection after the |
| 1772 | * user processes are gone, then RST the other end. |
| 1773 | */ |
| 1774 | if ((so->so_state & SS_NOFDREF) && |
| 1775 | tp->t_state > TCPS_CLOSE_WAIT && tlen) { |
| 1776 | tp = tcp_close(tp); |
| 1777 | tcpstat.tcps_rcvafterclose++; |
| 1778 | rstreason = BANDLIM_UNLIMITED; |
| 1779 | goto dropwithreset; |
| 1780 | } |
| 1781 | |
| 1782 | /* |
| 1783 | * If segment ends after window, drop trailing data |
| 1784 | * (and PUSH and FIN); if nothing left, just ACK. |
| 1785 | */ |
| 1786 | todrop = (th->th_seq + tlen) - (tp->rcv_nxt + tp->rcv_wnd); |
| 1787 | if (todrop > 0) { |
| 1788 | tcpstat.tcps_rcvpackafterwin++; |
| 1789 | if (todrop >= tlen) { |
| 1790 | tcpstat.tcps_rcvbyteafterwin += tlen; |
| 1791 | /* |
| 1792 | * If a new connection request is received |
| 1793 | * while in TIME_WAIT, drop the old connection |
| 1794 | * and start over if the sequence numbers |
| 1795 | * are above the previous ones. |
| 1796 | */ |
| 1797 | if (thflags & TH_SYN && |
| 1798 | tp->t_state == TCPS_TIME_WAIT && |
| 1799 | SEQ_GT(th->th_seq, tp->rcv_nxt)) { |
| 1800 | tp = tcp_close(tp); |
| 1801 | goto findpcb; |
| 1802 | } |
| 1803 | /* |
| 1804 | * If window is closed can only take segments at |
| 1805 | * window edge, and have to drop data and PUSH from |
| 1806 | * incoming segments. Continue processing, but |
| 1807 | * remember to ack. Otherwise, drop segment |
| 1808 | * and ack. |
| 1809 | */ |
| 1810 | if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) { |
| 1811 | tp->t_flags |= TF_ACKNOW; |
| 1812 | tcpstat.tcps_rcvwinprobe++; |
| 1813 | } else |
| 1814 | goto dropafterack; |
| 1815 | } else |
| 1816 | tcpstat.tcps_rcvbyteafterwin += todrop; |
| 1817 | m_adj(m, -todrop); |
| 1818 | tlen -= todrop; |
| 1819 | thflags &= ~(TH_PUSH | TH_FIN); |
| 1820 | } |
| 1821 | |
| 1822 | /* |
| 1823 | * If last ACK falls within this segment's sequence numbers, |
| 1824 | * record its timestamp. |
| 1825 | * NOTE: |
| 1826 | * 1) That the test incorporates suggestions from the latest |
| 1827 | * proposal of the tcplw@cray.com list (Braden 1993/04/26). |
| 1828 | * 2) That updating only on newer timestamps interferes with |
| 1829 | * our earlier PAWS tests, so this check should be solely |
| 1830 | * predicated on the sequence space of this segment. |
| 1831 | * 3) That we modify the segment boundary check to be |
| 1832 | * Last.ACK.Sent <= SEG.SEQ + SEG.LEN |
| 1833 | * instead of RFC1323's |
| 1834 | * Last.ACK.Sent < SEG.SEQ + SEG.LEN, |
| 1835 | * This modified check allows us to overcome RFC1323's |
| 1836 | * limitations as described in Stevens TCP/IP Illustrated |
| 1837 | * Vol. 2 p.869. In such cases, we can still calculate the |
| 1838 | * RTT correctly when RCV.NXT == Last.ACK.Sent. |
| 1839 | */ |
| 1840 | if ((to.to_flags & TOF_TS) && SEQ_LEQ(th->th_seq, tp->last_ack_sent) && |
| 1841 | SEQ_LEQ(tp->last_ack_sent, (th->th_seq + tlen |
| 1842 | + ((thflags & TH_SYN) != 0) |
| 1843 | + ((thflags & TH_FIN) != 0)))) { |
| 1844 | tp->ts_recent_age = ticks; |
| 1845 | tp->ts_recent = to.to_tsval; |
| 1846 | } |
| 1847 | |
| 1848 | /* |
| 1849 | * If a SYN is in the window, then this is an |
| 1850 | * error and we send an RST and drop the connection. |
| 1851 | */ |
| 1852 | if (thflags & TH_SYN) { |
| 1853 | tp = tcp_drop(tp, ECONNRESET); |
| 1854 | rstreason = BANDLIM_UNLIMITED; |
| 1855 | goto dropwithreset; |
| 1856 | } |
| 1857 | |
| 1858 | /* |
| 1859 | * If the ACK bit is off: if in SYN-RECEIVED state or SENDSYN |
| 1860 | * flag is on (half-synchronized state), then queue data for |
| 1861 | * later processing; else drop segment and return. |
| 1862 | */ |
| 1863 | if (!(thflags & TH_ACK)) { |
| 1864 | if (tp->t_state == TCPS_SYN_RECEIVED || |
| 1865 | (tp->t_flags & TF_NEEDSYN)) |
| 1866 | goto step6; |
| 1867 | else |
| 1868 | goto drop; |
| 1869 | } |
| 1870 | |
| 1871 | /* |
| 1872 | * Ack processing. |
| 1873 | */ |
| 1874 | switch (tp->t_state) { |
| 1875 | /* |
| 1876 | * In SYN_RECEIVED state, the ACK acknowledges our SYN, so enter |
| 1877 | * ESTABLISHED state and continue processing. |
| 1878 | * The ACK was checked above. |
| 1879 | */ |
| 1880 | case TCPS_SYN_RECEIVED: |
| 1881 | |
| 1882 | tcpstat.tcps_connects++; |
| 1883 | soisconnected(so); |
| 1884 | /* Do window scaling? */ |
| 1885 | if ((tp->t_flags & (TF_RCVD_SCALE | TF_REQ_SCALE)) == |
| 1886 | (TF_RCVD_SCALE | TF_REQ_SCALE)) { |
| 1887 | tp->snd_scale = tp->requested_s_scale; |
| 1888 | tp->rcv_scale = tp->request_r_scale; |
| 1889 | } |
| 1890 | /* |
| 1891 | * Make transitions: |
| 1892 | * SYN-RECEIVED -> ESTABLISHED |
| 1893 | * SYN-RECEIVED* -> FIN-WAIT-1 |
| 1894 | */ |
| 1895 | tp->t_starttime = ticks; |
| 1896 | if (tp->t_flags & TF_NEEDFIN) { |
| 1897 | tp->t_state = TCPS_FIN_WAIT_1; |
| 1898 | tp->t_flags &= ~TF_NEEDFIN; |
| 1899 | } else { |
| 1900 | tp->t_state = TCPS_ESTABLISHED; |
| 1901 | tcp_callout_reset(tp, tp->tt_keep, |
| 1902 | tcp_getkeepidle(tp), |
| 1903 | tcp_timer_keep); |
| 1904 | } |
| 1905 | /* |
| 1906 | * If segment contains data or ACK, will call tcp_reass() |
| 1907 | * later; if not, do so now to pass queued data to user. |
| 1908 | */ |
| 1909 | if (tlen == 0 && !(thflags & TH_FIN)) |
| 1910 | tcp_reass(tp, NULL, NULL, NULL); |
| 1911 | /* fall into ... */ |
| 1912 | |
| 1913 | /* |
| 1914 | * In ESTABLISHED state: drop duplicate ACKs; ACK out of range |
| 1915 | * ACKs. If the ack is in the range |
| 1916 | * tp->snd_una < th->th_ack <= tp->snd_max |
| 1917 | * then advance tp->snd_una to th->th_ack and drop |
| 1918 | * data from the retransmission queue. If this ACK reflects |
| 1919 | * more up to date window information we update our window information. |
| 1920 | */ |
| 1921 | case TCPS_ESTABLISHED: |
| 1922 | case TCPS_FIN_WAIT_1: |
| 1923 | case TCPS_FIN_WAIT_2: |
| 1924 | case TCPS_CLOSE_WAIT: |
| 1925 | case TCPS_CLOSING: |
| 1926 | case TCPS_LAST_ACK: |
| 1927 | case TCPS_TIME_WAIT: |
| 1928 | |
| 1929 | if (SEQ_LEQ(th->th_ack, tp->snd_una)) { |
| 1930 | if (TCP_DO_SACK(tp)) |
| 1931 | tcp_sack_update_scoreboard(tp, &to); |
| 1932 | if (tlen != 0 || tiwin != tp->snd_wnd) { |
| 1933 | tp->t_dupacks = 0; |
| 1934 | break; |
| 1935 | } |
| 1936 | tcpstat.tcps_rcvdupack++; |
| 1937 | if (!tcp_callout_active(tp, tp->tt_rexmt) || |
| 1938 | th->th_ack != tp->snd_una) { |
| 1939 | tp->t_dupacks = 0; |
| 1940 | break; |
| 1941 | } |
| 1942 | /* |
| 1943 | * We have outstanding data (other than |
| 1944 | * a window probe), this is a completely |
| 1945 | * duplicate ack (ie, window info didn't |
| 1946 | * change), the ack is the biggest we've |
| 1947 | * seen and we've seen exactly our rexmt |
| 1948 | * threshhold of them, so assume a packet |
| 1949 | * has been dropped and retransmit it. |
| 1950 | * Kludge snd_nxt & the congestion |
| 1951 | * window so we send only this one |
| 1952 | * packet. |
| 1953 | */ |
| 1954 | if (IN_FASTRECOVERY(tp)) { |
| 1955 | if (TCP_DO_SACK(tp)) { |
| 1956 | /* No artifical cwnd inflation. */ |
| 1957 | tcp_sack_rexmt(tp, th); |
| 1958 | } else { |
| 1959 | /* |
| 1960 | * Dup acks mean that packets |
| 1961 | * have left the network |
| 1962 | * (they're now cached at the |
| 1963 | * receiver) so bump cwnd by |
| 1964 | * the amount in the receiver |
| 1965 | * to keep a constant cwnd |
| 1966 | * packets in the network. |
| 1967 | */ |
| 1968 | tp->snd_cwnd += tp->t_maxseg; |
| 1969 | tcp_output(tp); |
| 1970 | } |
| 1971 | } else if (SEQ_LT(th->th_ack, tp->snd_recover)) { |
| 1972 | tp->t_dupacks = 0; |
| 1973 | break; |
| 1974 | } else if (++tp->t_dupacks == tcprexmtthresh) { |
| 1975 | tcp_seq old_snd_nxt; |
| 1976 | u_int win; |
| 1977 | |
| 1978 | fastretransmit: |
| 1979 | if (tcp_do_eifel_detect && |
| 1980 | (tp->t_flags & TF_RCVD_TSTMP)) { |
| 1981 | tcp_save_congestion_state(tp); |
| 1982 | tp->t_flags |= TF_FASTREXMT; |
| 1983 | } |
| 1984 | /* |
| 1985 | * We know we're losing at the current |
| 1986 | * window size, so do congestion avoidance: |
| 1987 | * set ssthresh to half the current window |
| 1988 | * and pull our congestion window back to the |
| 1989 | * new ssthresh. |
| 1990 | */ |
| 1991 | win = min(tp->snd_wnd, tp->snd_cwnd) / 2 / |
| 1992 | tp->t_maxseg; |
| 1993 | if (win < 2) |
| 1994 | win = 2; |
| 1995 | tp->snd_ssthresh = win * tp->t_maxseg; |
| 1996 | ENTER_FASTRECOVERY(tp); |
| 1997 | tp->snd_recover = tp->snd_max; |
| 1998 | tcp_callout_stop(tp, tp->tt_rexmt); |
| 1999 | tp->t_rtttime = 0; |
| 2000 | old_snd_nxt = tp->snd_nxt; |
| 2001 | tp->snd_nxt = th->th_ack; |
| 2002 | tp->snd_cwnd = tp->t_maxseg; |
| 2003 | tcp_output(tp); |
| 2004 | ++tcpstat.tcps_sndfastrexmit; |
| 2005 | tp->snd_cwnd = tp->snd_ssthresh; |
| 2006 | tp->rexmt_high = tp->snd_nxt; |
| 2007 | if (SEQ_GT(old_snd_nxt, tp->snd_nxt)) |
| 2008 | tp->snd_nxt = old_snd_nxt; |
| 2009 | KASSERT(tp->snd_limited <= 2, |
| 2010 | ("tp->snd_limited too big")); |
| 2011 | if (TCP_DO_SACK(tp)) |
| 2012 | tcp_sack_rexmt(tp, th); |
| 2013 | else |
| 2014 | tp->snd_cwnd += tp->t_maxseg * |
| 2015 | (tp->t_dupacks - tp->snd_limited); |
| 2016 | } else if (tcp_do_limitedtransmit) { |
| 2017 | u_long oldcwnd = tp->snd_cwnd; |
| 2018 | tcp_seq oldsndmax = tp->snd_max; |
| 2019 | tcp_seq oldsndnxt = tp->snd_nxt; |
| 2020 | /* outstanding data */ |
| 2021 | uint32_t ownd = tp->snd_max - tp->snd_una; |
| 2022 | u_int sent; |
| 2023 | |
| 2024 | #define iceildiv(n, d) (((n)+(d)-1) / (d)) |
| 2025 | |
| 2026 | KASSERT(tp->t_dupacks == 1 || |
| 2027 | tp->t_dupacks == 2, |
| 2028 | ("dupacks not 1 or 2")); |
| 2029 | if (tp->t_dupacks == 1) |
| 2030 | tp->snd_limited = 0; |
| 2031 | tp->snd_nxt = tp->snd_max; |
| 2032 | tp->snd_cwnd = ownd + |
| 2033 | (tp->t_dupacks - tp->snd_limited) * |
| 2034 | tp->t_maxseg; |
| 2035 | tcp_output(tp); |
| 2036 | |
| 2037 | /* |
| 2038 | * Other acks may have been processed, |
| 2039 | * snd_nxt cannot be reset to a value less |
| 2040 | * then snd_una. |
| 2041 | */ |
| 2042 | if (SEQ_LT(oldsndnxt, oldsndmax)) { |
| 2043 | if (SEQ_GT(oldsndnxt, tp->snd_una)) |
| 2044 | tp->snd_nxt = oldsndnxt; |
| 2045 | else |
| 2046 | tp->snd_nxt = tp->snd_una; |
| 2047 | } |
| 2048 | tp->snd_cwnd = oldcwnd; |
| 2049 | sent = tp->snd_max - oldsndmax; |
| 2050 | if (sent > tp->t_maxseg) { |
| 2051 | KASSERT((tp->t_dupacks == 2 && |
| 2052 | tp->snd_limited == 0) || |
| 2053 | (sent == tp->t_maxseg + 1 && |
| 2054 | tp->t_flags & TF_SENTFIN), |
| 2055 | ("sent too much")); |
| 2056 | KASSERT(sent <= tp->t_maxseg * 2, |
| 2057 | ("sent too many segments")); |
| 2058 | tp->snd_limited = 2; |
| 2059 | tcpstat.tcps_sndlimited += 2; |
| 2060 | } else if (sent > 0) { |
| 2061 | ++tp->snd_limited; |
| 2062 | ++tcpstat.tcps_sndlimited; |
| 2063 | } else if (tcp_do_early_retransmit && |
| 2064 | (tcp_do_eifel_detect && |
| 2065 | (tp->t_flags & TF_RCVD_TSTMP)) && |
| 2066 | ownd < 4 * tp->t_maxseg && |
| 2067 | tp->t_dupacks + 1 >= |
| 2068 | iceildiv(ownd, tp->t_maxseg) && |
| 2069 | (!TCP_DO_SACK(tp) || |
| 2070 | ownd <= tp->t_maxseg || |
| 2071 | tcp_sack_has_sacked(&tp->scb, |
| 2072 | ownd - tp->t_maxseg))) { |
| 2073 | ++tcpstat.tcps_sndearlyrexmit; |
| 2074 | tp->t_flags |= TF_EARLYREXMT; |
| 2075 | goto fastretransmit; |
| 2076 | } |
| 2077 | } |
| 2078 | goto drop; |
| 2079 | } |
| 2080 | |
| 2081 | KASSERT(SEQ_GT(th->th_ack, tp->snd_una), ("th_ack <= snd_una")); |
| 2082 | tp->t_dupacks = 0; |
| 2083 | if (SEQ_GT(th->th_ack, tp->snd_max)) { |
| 2084 | /* |
| 2085 | * Detected optimistic ACK attack. |
| 2086 | * Force slow-start to de-synchronize attack. |
| 2087 | */ |
| 2088 | tp->snd_cwnd = tp->t_maxseg; |
| 2089 | tp->snd_wacked = 0; |
| 2090 | |
| 2091 | tcpstat.tcps_rcvacktoomuch++; |
| 2092 | goto dropafterack; |
| 2093 | } |
| 2094 | /* |
| 2095 | * If we reach this point, ACK is not a duplicate, |
| 2096 | * i.e., it ACKs something we sent. |
| 2097 | */ |
| 2098 | if (tp->t_flags & TF_NEEDSYN) { |
| 2099 | /* |
| 2100 | * T/TCP: Connection was half-synchronized, and our |
| 2101 | * SYN has been ACK'd (so connection is now fully |
| 2102 | * synchronized). Go to non-starred state, |
| 2103 | * increment snd_una for ACK of SYN, and check if |
| 2104 | * we can do window scaling. |
| 2105 | */ |
| 2106 | tp->t_flags &= ~TF_NEEDSYN; |
| 2107 | tp->snd_una++; |
| 2108 | /* Do window scaling? */ |
| 2109 | if ((tp->t_flags & (TF_RCVD_SCALE | TF_REQ_SCALE)) == |
| 2110 | (TF_RCVD_SCALE | TF_REQ_SCALE)) { |
| 2111 | tp->snd_scale = tp->requested_s_scale; |
| 2112 | tp->rcv_scale = tp->request_r_scale; |
| 2113 | } |
| 2114 | } |
| 2115 | |
| 2116 | process_ACK: |
| 2117 | acked = th->th_ack - tp->snd_una; |
| 2118 | tcpstat.tcps_rcvackpack++; |
| 2119 | tcpstat.tcps_rcvackbyte += acked; |
| 2120 | |
| 2121 | if (tcp_do_eifel_detect && acked > 0 && |
| 2122 | (to.to_flags & TOF_TS) && (to.to_tsecr != 0) && |
| 2123 | (tp->t_flags & TF_FIRSTACCACK)) { |
| 2124 | /* Eifel detection applicable. */ |
| 2125 | if (to.to_tsecr < tp->t_rexmtTS) { |
| 2126 | ++tcpstat.tcps_eifeldetected; |
| 2127 | tcp_revert_congestion_state(tp); |
| 2128 | if (tp->t_rxtshift == 1 && |
| 2129 | ticks >= tp->t_badrxtwin) |
| 2130 | ++tcpstat.tcps_rttcantdetect; |
| 2131 | } |
| 2132 | } else if (tp->t_rxtshift == 1 && ticks < tp->t_badrxtwin) { |
| 2133 | /* |
| 2134 | * If we just performed our first retransmit, |
| 2135 | * and the ACK arrives within our recovery window, |
| 2136 | * then it was a mistake to do the retransmit |
| 2137 | * in the first place. Recover our original cwnd |
| 2138 | * and ssthresh, and proceed to transmit where we |
| 2139 | * left off. |
| 2140 | */ |
| 2141 | tcp_revert_congestion_state(tp); |
| 2142 | ++tcpstat.tcps_rttdetected; |
| 2143 | } |
| 2144 | |
| 2145 | /* |
| 2146 | * If we have a timestamp reply, update smoothed |
| 2147 | * round trip time. If no timestamp is present but |
| 2148 | * transmit timer is running and timed sequence |
| 2149 | * number was acked, update smoothed round trip time. |
| 2150 | * Since we now have an rtt measurement, cancel the |
| 2151 | * timer backoff (cf., Phil Karn's retransmit alg.). |
| 2152 | * Recompute the initial retransmit timer. |
| 2153 | * |
| 2154 | * Some machines (certain windows boxes) send broken |
| 2155 | * timestamp replies during the SYN+ACK phase, ignore |
| 2156 | * timestamps of 0. |
| 2157 | */ |
| 2158 | if ((to.to_flags & TOF_TS) && (to.to_tsecr != 0)) |
| 2159 | tcp_xmit_timer(tp, ticks - to.to_tsecr + 1); |
| 2160 | else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq)) |
| 2161 | tcp_xmit_timer(tp, ticks - tp->t_rtttime); |
| 2162 | tcp_xmit_bandwidth_limit(tp, th->th_ack); |
| 2163 | |
| 2164 | /* |
| 2165 | * If no data (only SYN) was ACK'd, |
| 2166 | * skip rest of ACK processing. |
| 2167 | */ |
| 2168 | if (acked == 0) |
| 2169 | goto step6; |
| 2170 | |
| 2171 | /* Stop looking for an acceptable ACK since one was received. */ |
| 2172 | tp->t_flags &= ~(TF_FIRSTACCACK | TF_FASTREXMT | TF_EARLYREXMT); |
| 2173 | |
| 2174 | if (acked > so->so_snd.ssb_cc) { |
| 2175 | tp->snd_wnd -= so->so_snd.ssb_cc; |
| 2176 | sbdrop(&so->so_snd.sb, (int)so->so_snd.ssb_cc); |
| 2177 | ourfinisacked = TRUE; |
| 2178 | } else { |
| 2179 | sbdrop(&so->so_snd.sb, acked); |
| 2180 | tp->snd_wnd -= acked; |
| 2181 | ourfinisacked = FALSE; |
| 2182 | } |
| 2183 | sowwakeup(so); |
| 2184 | |
| 2185 | /* |
| 2186 | * Update window information. |
| 2187 | * Don't look at window if no ACK: |
| 2188 | * TAC's send garbage on first SYN. |
| 2189 | */ |
| 2190 | if (SEQ_LT(tp->snd_wl1, th->th_seq) || |
| 2191 | (tp->snd_wl1 == th->th_seq && |
| 2192 | (SEQ_LT(tp->snd_wl2, th->th_ack) || |
| 2193 | (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd)))) { |
| 2194 | /* keep track of pure window updates */ |
| 2195 | if (tlen == 0 && tp->snd_wl2 == th->th_ack && |
| 2196 | tiwin > tp->snd_wnd) |
| 2197 | tcpstat.tcps_rcvwinupd++; |
| 2198 | tp->snd_wnd = tiwin; |
| 2199 | tp->snd_wl1 = th->th_seq; |
| 2200 | tp->snd_wl2 = th->th_ack; |
| 2201 | if (tp->snd_wnd > tp->max_sndwnd) |
| 2202 | tp->max_sndwnd = tp->snd_wnd; |
| 2203 | needoutput = TRUE; |
| 2204 | } |
| 2205 | |
| 2206 | tp->snd_una = th->th_ack; |
| 2207 | if (TCP_DO_SACK(tp)) |
| 2208 | tcp_sack_update_scoreboard(tp, &to); |
| 2209 | if (IN_FASTRECOVERY(tp)) { |
| 2210 | if (SEQ_GEQ(th->th_ack, tp->snd_recover)) { |
| 2211 | EXIT_FASTRECOVERY(tp); |
| 2212 | needoutput = TRUE; |
| 2213 | /* |
| 2214 | * If the congestion window was inflated |
| 2215 | * to account for the other side's |
| 2216 | * cached packets, retract it. |
| 2217 | */ |
| 2218 | if (!TCP_DO_SACK(tp)) |
| 2219 | tp->snd_cwnd = tp->snd_ssthresh; |
| 2220 | |
| 2221 | /* |
| 2222 | * Window inflation should have left us |
| 2223 | * with approximately snd_ssthresh outstanding |
| 2224 | * data. But, in case we would be inclined |
| 2225 | * to send a burst, better do it using |
| 2226 | * slow start. |
| 2227 | */ |
| 2228 | if (SEQ_GT(th->th_ack + tp->snd_cwnd, |
| 2229 | tp->snd_max + 2 * tp->t_maxseg)) |
| 2230 | tp->snd_cwnd = |
| 2231 | (tp->snd_max - tp->snd_una) + |
| 2232 | 2 * tp->t_maxseg; |
| 2233 | |
| 2234 | tp->snd_wacked = 0; |
| 2235 | } else { |
| 2236 | if (TCP_DO_SACK(tp)) { |
| 2237 | tp->snd_max_rexmt = tp->snd_max; |
| 2238 | tcp_sack_rexmt(tp, th); |
| 2239 | } else { |
| 2240 | tcp_newreno_partial_ack(tp, th, acked); |
| 2241 | } |
| 2242 | needoutput = FALSE; |
| 2243 | } |
| 2244 | } else { |
| 2245 | /* |
| 2246 | * Open the congestion window. When in slow-start, |
| 2247 | * open exponentially: maxseg per packet. Otherwise, |
| 2248 | * open linearly: maxseg per window. |
| 2249 | */ |
| 2250 | if (tp->snd_cwnd <= tp->snd_ssthresh) { |
| 2251 | u_int abc_sslimit = |
| 2252 | (SEQ_LT(tp->snd_nxt, tp->snd_max) ? |
| 2253 | tp->t_maxseg : 2 * tp->t_maxseg); |
| 2254 | |
| 2255 | /* slow-start */ |
| 2256 | tp->snd_cwnd += tcp_do_abc ? |
| 2257 | min(acked, abc_sslimit) : tp->t_maxseg; |
| 2258 | } else { |
| 2259 | /* linear increase */ |
| 2260 | tp->snd_wacked += tcp_do_abc ? acked : |
| 2261 | tp->t_maxseg; |
| 2262 | if (tp->snd_wacked >= tp->snd_cwnd) { |
| 2263 | tp->snd_wacked -= tp->snd_cwnd; |
| 2264 | tp->snd_cwnd += tp->t_maxseg; |
| 2265 | } |
| 2266 | } |
| 2267 | tp->snd_cwnd = min(tp->snd_cwnd, |
| 2268 | TCP_MAXWIN << tp->snd_scale); |
| 2269 | tp->snd_recover = th->th_ack - 1; |
| 2270 | } |
| 2271 | if (SEQ_LT(tp->snd_nxt, tp->snd_una)) |
| 2272 | tp->snd_nxt = tp->snd_una; |
| 2273 | |
| 2274 | /* |
| 2275 | * If all outstanding data is acked, stop retransmit |
| 2276 | * timer and remember to restart (more output or persist). |
| 2277 | * If there is more data to be acked, restart retransmit |
| 2278 | * timer, using current (possibly backed-off) value. |
| 2279 | */ |
| 2280 | if (th->th_ack == tp->snd_max) { |
| 2281 | tcp_callout_stop(tp, tp->tt_rexmt); |
| 2282 | needoutput = TRUE; |
| 2283 | } else if (!tcp_callout_active(tp, tp->tt_persist)) { |
| 2284 | tcp_callout_reset(tp, tp->tt_rexmt, tp->t_rxtcur, |
| 2285 | tcp_timer_rexmt); |
| 2286 | } |
| 2287 | |
| 2288 | switch (tp->t_state) { |
| 2289 | /* |
| 2290 | * In FIN_WAIT_1 STATE in addition to the processing |
| 2291 | * for the ESTABLISHED state if our FIN is now acknowledged |
| 2292 | * then enter FIN_WAIT_2. |
| 2293 | */ |
| 2294 | case TCPS_FIN_WAIT_1: |
| 2295 | if (ourfinisacked) { |
| 2296 | /* |
| 2297 | * If we can't receive any more |
| 2298 | * data, then closing user can proceed. |
| 2299 | * Starting the timer is contrary to the |
| 2300 | * specification, but if we don't get a FIN |
| 2301 | * we'll hang forever. |
| 2302 | */ |
| 2303 | if (so->so_state & SS_CANTRCVMORE) { |
| 2304 | soisdisconnected(so); |
| 2305 | tcp_callout_reset(tp, tp->tt_2msl, |
| 2306 | tcp_maxidle, tcp_timer_2msl); |
| 2307 | } |
| 2308 | tp->t_state = TCPS_FIN_WAIT_2; |
| 2309 | } |
| 2310 | break; |
| 2311 | |
| 2312 | /* |
| 2313 | * In CLOSING STATE in addition to the processing for |
| 2314 | * the ESTABLISHED state if the ACK acknowledges our FIN |
| 2315 | * then enter the TIME-WAIT state, otherwise ignore |
| 2316 | * the segment. |
| 2317 | */ |
| 2318 | case TCPS_CLOSING: |
| 2319 | if (ourfinisacked) { |
| 2320 | tp->t_state = TCPS_TIME_WAIT; |
| 2321 | tcp_canceltimers(tp); |
| 2322 | tcp_callout_reset(tp, tp->tt_2msl, |
| 2323 | 2 * tcp_msl, tcp_timer_2msl); |
| 2324 | soisdisconnected(so); |
| 2325 | } |
| 2326 | break; |
| 2327 | |
| 2328 | /* |
| 2329 | * In LAST_ACK, we may still be waiting for data to drain |
| 2330 | * and/or to be acked, as well as for the ack of our FIN. |
| 2331 | * If our FIN is now acknowledged, delete the TCB, |
| 2332 | * enter the closed state and return. |
| 2333 | */ |
| 2334 | case TCPS_LAST_ACK: |
| 2335 | if (ourfinisacked) { |
| 2336 | tp = tcp_close(tp); |
| 2337 | goto drop; |
| 2338 | } |
| 2339 | break; |
| 2340 | |
| 2341 | /* |
| 2342 | * In TIME_WAIT state the only thing that should arrive |
| 2343 | * is a retransmission of the remote FIN. Acknowledge |
| 2344 | * it and restart the finack timer. |
| 2345 | */ |
| 2346 | case TCPS_TIME_WAIT: |
| 2347 | tcp_callout_reset(tp, tp->tt_2msl, 2 * tcp_msl, |
| 2348 | tcp_timer_2msl); |
| 2349 | goto dropafterack; |
| 2350 | } |
| 2351 | } |
| 2352 | |
| 2353 | step6: |
| 2354 | /* |
| 2355 | * Update window information. |
| 2356 | * Don't look at window if no ACK: TAC's send garbage on first SYN. |
| 2357 | */ |
| 2358 | if ((thflags & TH_ACK) && |
| 2359 | acceptable_window_update(tp, th, tiwin)) { |
| 2360 | /* keep track of pure window updates */ |
| 2361 | if (tlen == 0 && tp->snd_wl2 == th->th_ack && |
| 2362 | tiwin > tp->snd_wnd) |
| 2363 | tcpstat.tcps_rcvwinupd++; |
| 2364 | tp->snd_wnd = tiwin; |
| 2365 | tp->snd_wl1 = th->th_seq; |
| 2366 | tp->snd_wl2 = th->th_ack; |
| 2367 | if (tp->snd_wnd > tp->max_sndwnd) |
| 2368 | tp->max_sndwnd = tp->snd_wnd; |
| 2369 | needoutput = TRUE; |
| 2370 | } |
| 2371 | |
| 2372 | /* |
| 2373 | * Process segments with URG. |
| 2374 | */ |
| 2375 | if ((thflags & TH_URG) && th->th_urp && |
| 2376 | !TCPS_HAVERCVDFIN(tp->t_state)) { |
| 2377 | /* |
| 2378 | * This is a kludge, but if we receive and accept |
| 2379 | * random urgent pointers, we'll crash in |
| 2380 | * soreceive. It's hard to imagine someone |
| 2381 | * actually wanting to send this much urgent data. |
| 2382 | */ |
| 2383 | if (th->th_urp + so->so_rcv.ssb_cc > sb_max) { |
| 2384 | th->th_urp = 0; /* XXX */ |
| 2385 | thflags &= ~TH_URG; /* XXX */ |
| 2386 | goto dodata; /* XXX */ |
| 2387 | } |
| 2388 | /* |
| 2389 | * If this segment advances the known urgent pointer, |
| 2390 | * then mark the data stream. This should not happen |
| 2391 | * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since |
| 2392 | * a FIN has been received from the remote side. |
| 2393 | * In these states we ignore the URG. |
| 2394 | * |
| 2395 | * According to RFC961 (Assigned Protocols), |
| 2396 | * the urgent pointer points to the last octet |
| 2397 | * of urgent data. We continue, however, |
| 2398 | * to consider it to indicate the first octet |
| 2399 | * of data past the urgent section as the original |
| 2400 | * spec states (in one of two places). |
| 2401 | */ |
| 2402 | if (SEQ_GT(th->th_seq + th->th_urp, tp->rcv_up)) { |
| 2403 | tp->rcv_up = th->th_seq + th->th_urp; |
| 2404 | so->so_oobmark = so->so_rcv.ssb_cc + |
| 2405 | (tp->rcv_up - tp->rcv_nxt) - 1; |
| 2406 | if (so->so_oobmark == 0) |
| 2407 | sosetstate(so, SS_RCVATMARK); |
| 2408 | sohasoutofband(so); |
| 2409 | tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA); |
| 2410 | } |
| 2411 | /* |
| 2412 | * Remove out of band data so doesn't get presented to user. |
| 2413 | * This can happen independent of advancing the URG pointer, |
| 2414 | * but if two URG's are pending at once, some out-of-band |
| 2415 | * data may creep in... ick. |
| 2416 | */ |
| 2417 | if (th->th_urp <= (u_long)tlen && |
| 2418 | !(so->so_options & SO_OOBINLINE)) { |
| 2419 | /* hdr drop is delayed */ |
| 2420 | tcp_pulloutofband(so, th, m, drop_hdrlen); |
| 2421 | } |
| 2422 | } else { |
| 2423 | /* |
| 2424 | * If no out of band data is expected, |
| 2425 | * pull receive urgent pointer along |
| 2426 | * with the receive window. |
| 2427 | */ |
| 2428 | if (SEQ_GT(tp->rcv_nxt, tp->rcv_up)) |
| 2429 | tp->rcv_up = tp->rcv_nxt; |
| 2430 | } |
| 2431 | |
| 2432 | dodata: /* XXX */ |
| 2433 | /* |
| 2434 | * Process the segment text, merging it into the TCP sequencing queue, |
| 2435 | * and arranging for acknowledgment of receipt if necessary. |
| 2436 | * This process logically involves adjusting tp->rcv_wnd as data |
| 2437 | * is presented to the user (this happens in tcp_usrreq.c, |
| 2438 | * case PRU_RCVD). If a FIN has already been received on this |
| 2439 | * connection then we just ignore the text. |
| 2440 | */ |
| 2441 | if ((tlen || (thflags & TH_FIN)) && !TCPS_HAVERCVDFIN(tp->t_state)) { |
| 2442 | m_adj(m, drop_hdrlen); /* delayed header drop */ |
| 2443 | /* |
| 2444 | * Insert segment which includes th into TCP reassembly queue |
| 2445 | * with control block tp. Set thflags to whether reassembly now |
| 2446 | * includes a segment with FIN. This handles the common case |
| 2447 | * inline (segment is the next to be received on an established |
| 2448 | * connection, and the queue is empty), avoiding linkage into |
| 2449 | * and removal from the queue and repetition of various |
| 2450 | * conversions. |
| 2451 | * Set DELACK for segments received in order, but ack |
| 2452 | * immediately when segments are out of order (so |
| 2453 | * fast retransmit can work). |
| 2454 | */ |
| 2455 | if (th->th_seq == tp->rcv_nxt && |
| 2456 | LIST_EMPTY(&tp->t_segq) && |
| 2457 | TCPS_HAVEESTABLISHED(tp->t_state)) { |
| 2458 | if (DELAY_ACK(tp)) { |
| 2459 | tcp_callout_reset(tp, tp->tt_delack, |
| 2460 | tcp_delacktime, tcp_timer_delack); |
| 2461 | } else { |
| 2462 | tp->t_flags |= TF_ACKNOW; |
| 2463 | } |
| 2464 | tp->rcv_nxt += tlen; |
| 2465 | thflags = th->th_flags & TH_FIN; |
| 2466 | tcpstat.tcps_rcvpack++; |
| 2467 | tcpstat.tcps_rcvbyte += tlen; |
| 2468 | ND6_HINT(tp); |
| 2469 | if (so->so_state & SS_CANTRCVMORE) { |
| 2470 | m_freem(m); |
| 2471 | } else { |
| 2472 | lwkt_gettoken(&so->so_rcv.ssb_token); |
| 2473 | ssb_appendstream(&so->so_rcv, m); |
| 2474 | lwkt_reltoken(&so->so_rcv.ssb_token); |
| 2475 | } |
| 2476 | sorwakeup(so); |
| 2477 | } else { |
| 2478 | if (!(tp->t_flags & TF_DUPSEG)) { |
| 2479 | /* Initialize SACK report block. */ |
| 2480 | tp->reportblk.rblk_start = th->th_seq; |
| 2481 | tp->reportblk.rblk_end = th->th_seq + tlen + |
| 2482 | ((thflags & TH_FIN) != 0); |
| 2483 | } |
| 2484 | thflags = tcp_reass(tp, th, &tlen, m); |
| 2485 | tp->t_flags |= TF_ACKNOW; |
| 2486 | } |
| 2487 | |
| 2488 | /* |
| 2489 | * Note the amount of data that peer has sent into |
| 2490 | * our window, in order to estimate the sender's |
| 2491 | * buffer size. |
| 2492 | */ |
| 2493 | len = so->so_rcv.ssb_hiwat - (tp->rcv_adv - tp->rcv_nxt); |
| 2494 | } else { |
| 2495 | m_freem(m); |
| 2496 | thflags &= ~TH_FIN; |
| 2497 | } |
| 2498 | |
| 2499 | /* |
| 2500 | * If FIN is received ACK the FIN and let the user know |
| 2501 | * that the connection is closing. |
| 2502 | */ |
| 2503 | if (thflags & TH_FIN) { |
| 2504 | if (!TCPS_HAVERCVDFIN(tp->t_state)) { |
| 2505 | socantrcvmore(so); |
| 2506 | /* |
| 2507 | * If connection is half-synchronized |
| 2508 | * (ie NEEDSYN flag on) then delay ACK, |
| 2509 | * so it may be piggybacked when SYN is sent. |
| 2510 | * Otherwise, since we received a FIN then no |
| 2511 | * more input can be expected, send ACK now. |
| 2512 | */ |
| 2513 | if (DELAY_ACK(tp) && (tp->t_flags & TF_NEEDSYN)) { |
| 2514 | tcp_callout_reset(tp, tp->tt_delack, |
| 2515 | tcp_delacktime, tcp_timer_delack); |
| 2516 | } else { |
| 2517 | tp->t_flags |= TF_ACKNOW; |
| 2518 | } |
| 2519 | tp->rcv_nxt++; |
| 2520 | } |
| 2521 | |
| 2522 | switch (tp->t_state) { |
| 2523 | /* |
| 2524 | * In SYN_RECEIVED and ESTABLISHED STATES |
| 2525 | * enter the CLOSE_WAIT state. |
| 2526 | */ |
| 2527 | case TCPS_SYN_RECEIVED: |
| 2528 | tp->t_starttime = ticks; |
| 2529 | /*FALLTHROUGH*/ |
| 2530 | case TCPS_ESTABLISHED: |
| 2531 | tp->t_state = TCPS_CLOSE_WAIT; |
| 2532 | break; |
| 2533 | |
| 2534 | /* |
| 2535 | * If still in FIN_WAIT_1 STATE FIN has not been acked so |
| 2536 | * enter the CLOSING state. |
| 2537 | */ |
| 2538 | case TCPS_FIN_WAIT_1: |
| 2539 | tp->t_state = TCPS_CLOSING; |
| 2540 | break; |
| 2541 | |
| 2542 | /* |
| 2543 | * In FIN_WAIT_2 state enter the TIME_WAIT state, |
| 2544 | * starting the time-wait timer, turning off the other |
| 2545 | * standard timers. |
| 2546 | */ |
| 2547 | case TCPS_FIN_WAIT_2: |
| 2548 | tp->t_state = TCPS_TIME_WAIT; |
| 2549 | tcp_canceltimers(tp); |
| 2550 | tcp_callout_reset(tp, tp->tt_2msl, 2 * tcp_msl, |
| 2551 | tcp_timer_2msl); |
| 2552 | soisdisconnected(so); |
| 2553 | break; |
| 2554 | |
| 2555 | /* |
| 2556 | * In TIME_WAIT state restart the 2 MSL time_wait timer. |
| 2557 | */ |
| 2558 | case TCPS_TIME_WAIT: |
| 2559 | tcp_callout_reset(tp, tp->tt_2msl, 2 * tcp_msl, |
| 2560 | tcp_timer_2msl); |
| 2561 | break; |
| 2562 | } |
| 2563 | } |
| 2564 | |
| 2565 | #ifdef TCPDEBUG |
| 2566 | if (so->so_options & SO_DEBUG) |
| 2567 | tcp_trace(TA_INPUT, ostate, tp, tcp_saveipgen, &tcp_savetcp, 0); |
| 2568 | #endif |
| 2569 | |
| 2570 | /* |
| 2571 | * Return any desired output. |
| 2572 | */ |
| 2573 | if (needoutput || (tp->t_flags & TF_ACKNOW)) |
| 2574 | tcp_output(tp); |
| 2575 | return(IPPROTO_DONE); |
| 2576 | |
| 2577 | dropafterack: |
| 2578 | /* |
| 2579 | * Generate an ACK dropping incoming segment if it occupies |
| 2580 | * sequence space, where the ACK reflects our state. |
| 2581 | * |
| 2582 | * We can now skip the test for the RST flag since all |
| 2583 | * paths to this code happen after packets containing |
| 2584 | * RST have been dropped. |
| 2585 | * |
| 2586 | * In the SYN-RECEIVED state, don't send an ACK unless the |
| 2587 | * segment we received passes the SYN-RECEIVED ACK test. |
| 2588 | * If it fails send a RST. This breaks the loop in the |
| 2589 | * "LAND" DoS attack, and also prevents an ACK storm |
| 2590 | * between two listening ports that have been sent forged |
| 2591 | * SYN segments, each with the source address of the other. |
| 2592 | */ |
| 2593 | if (tp->t_state == TCPS_SYN_RECEIVED && (thflags & TH_ACK) && |
| 2594 | (SEQ_GT(tp->snd_una, th->th_ack) || |
| 2595 | SEQ_GT(th->th_ack, tp->snd_max)) ) { |
| 2596 | rstreason = BANDLIM_RST_OPENPORT; |
| 2597 | goto dropwithreset; |
| 2598 | } |
| 2599 | #ifdef TCPDEBUG |
| 2600 | if (so->so_options & SO_DEBUG) |
| 2601 | tcp_trace(TA_DROP, ostate, tp, tcp_saveipgen, &tcp_savetcp, 0); |
| 2602 | #endif |
| 2603 | m_freem(m); |
| 2604 | tp->t_flags |= TF_ACKNOW; |
| 2605 | tcp_output(tp); |
| 2606 | return(IPPROTO_DONE); |
| 2607 | |
| 2608 | dropwithreset: |
| 2609 | /* |
| 2610 | * Generate a RST, dropping incoming segment. |
| 2611 | * Make ACK acceptable to originator of segment. |
| 2612 | * Don't bother to respond if destination was broadcast/multicast. |
| 2613 | */ |
| 2614 | if ((thflags & TH_RST) || m->m_flags & (M_BCAST | M_MCAST)) |
| 2615 | goto drop; |
| 2616 | if (isipv6) { |
| 2617 | if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) || |
| 2618 | IN6_IS_ADDR_MULTICAST(&ip6->ip6_src)) |
| 2619 | goto drop; |
| 2620 | } else { |
| 2621 | if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) || |
| 2622 | IN_MULTICAST(ntohl(ip->ip_src.s_addr)) || |
| 2623 | ip->ip_src.s_addr == htonl(INADDR_BROADCAST) || |
| 2624 | in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) |
| 2625 | goto drop; |
| 2626 | } |
| 2627 | /* IPv6 anycast check is done at tcp6_input() */ |
| 2628 | |
| 2629 | /* |
| 2630 | * Perform bandwidth limiting. |
| 2631 | */ |
| 2632 | #ifdef ICMP_BANDLIM |
| 2633 | if (badport_bandlim(rstreason) < 0) |
| 2634 | goto drop; |
| 2635 | #endif |
| 2636 | |
| 2637 | #ifdef TCPDEBUG |
| 2638 | if (tp == NULL || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) |
| 2639 | tcp_trace(TA_DROP, ostate, tp, tcp_saveipgen, &tcp_savetcp, 0); |
| 2640 | #endif |
| 2641 | if (thflags & TH_ACK) |
| 2642 | /* mtod() below is safe as long as hdr dropping is delayed */ |
| 2643 | tcp_respond(tp, mtod(m, void *), th, m, (tcp_seq)0, th->th_ack, |
| 2644 | TH_RST); |
| 2645 | else { |
| 2646 | if (thflags & TH_SYN) |
| 2647 | tlen++; |
| 2648 | /* mtod() below is safe as long as hdr dropping is delayed */ |
| 2649 | tcp_respond(tp, mtod(m, void *), th, m, th->th_seq + tlen, |
| 2650 | (tcp_seq)0, TH_RST | TH_ACK); |
| 2651 | } |
| 2652 | return(IPPROTO_DONE); |
| 2653 | |
| 2654 | drop: |
| 2655 | /* |
| 2656 | * Drop space held by incoming segment and return. |
| 2657 | */ |
| 2658 | #ifdef TCPDEBUG |
| 2659 | if (tp == NULL || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG)) |
| 2660 | tcp_trace(TA_DROP, ostate, tp, tcp_saveipgen, &tcp_savetcp, 0); |
| 2661 | #endif |
| 2662 | m_freem(m); |
| 2663 | return(IPPROTO_DONE); |
| 2664 | } |
| 2665 | |
| 2666 | /* |
| 2667 | * Parse TCP options and place in tcpopt. |
| 2668 | */ |
| 2669 | static void |
| 2670 | tcp_dooptions(struct tcpopt *to, u_char *cp, int cnt, boolean_t is_syn) |
| 2671 | { |
| 2672 | int opt, optlen, i; |
| 2673 | |
| 2674 | to->to_flags = 0; |
| 2675 | for (; cnt > 0; cnt -= optlen, cp += optlen) { |
| 2676 | opt = cp[0]; |
| 2677 | if (opt == TCPOPT_EOL) |
| 2678 | break; |
| 2679 | if (opt == TCPOPT_NOP) |
| 2680 | optlen = 1; |
| 2681 | else { |
| 2682 | if (cnt < 2) |
| 2683 | break; |
| 2684 | optlen = cp[1]; |
| 2685 | if (optlen < 2 || optlen > cnt) |
| 2686 | break; |
| 2687 | } |
| 2688 | switch (opt) { |
| 2689 | case TCPOPT_MAXSEG: |
| 2690 | if (optlen != TCPOLEN_MAXSEG) |
| 2691 | continue; |
| 2692 | if (!is_syn) |
| 2693 | continue; |
| 2694 | to->to_flags |= TOF_MSS; |
| 2695 | bcopy(cp + 2, &to->to_mss, sizeof to->to_mss); |
| 2696 | to->to_mss = ntohs(to->to_mss); |
| 2697 | break; |
| 2698 | case TCPOPT_WINDOW: |
| 2699 | if (optlen != TCPOLEN_WINDOW) |
| 2700 | continue; |
| 2701 | if (!is_syn) |
| 2702 | continue; |
| 2703 | to->to_flags |= TOF_SCALE; |
| 2704 | to->to_requested_s_scale = min(cp[2], TCP_MAX_WINSHIFT); |
| 2705 | break; |
| 2706 | case TCPOPT_TIMESTAMP: |
| 2707 | if (optlen != TCPOLEN_TIMESTAMP) |
| 2708 | continue; |
| 2709 | to->to_flags |= TOF_TS; |
| 2710 | bcopy(cp + 2, &to->to_tsval, sizeof to->to_tsval); |
| 2711 | to->to_tsval = ntohl(to->to_tsval); |
| 2712 | bcopy(cp + 6, &to->to_tsecr, sizeof to->to_tsecr); |
| 2713 | to->to_tsecr = ntohl(to->to_tsecr); |
| 2714 | /* |
| 2715 | * If echoed timestamp is later than the current time, |
| 2716 | * fall back to non RFC1323 RTT calculation. |
| 2717 | */ |
| 2718 | if (to->to_tsecr != 0 && TSTMP_GT(to->to_tsecr, ticks)) |
| 2719 | to->to_tsecr = 0; |
| 2720 | break; |
| 2721 | case TCPOPT_SACK_PERMITTED: |
| 2722 | if (optlen != TCPOLEN_SACK_PERMITTED) |
| 2723 | continue; |
| 2724 | if (!is_syn) |
| 2725 | continue; |
| 2726 | to->to_flags |= TOF_SACK_PERMITTED; |
| 2727 | break; |
| 2728 | case TCPOPT_SACK: |
| 2729 | if ((optlen - 2) & 0x07) /* not multiple of 8 */ |
| 2730 | continue; |
| 2731 | to->to_nsackblocks = (optlen - 2) / 8; |
| 2732 | to->to_sackblocks = (struct raw_sackblock *) (cp + 2); |
| 2733 | to->to_flags |= TOF_SACK; |
| 2734 | for (i = 0; i < to->to_nsackblocks; i++) { |
| 2735 | struct raw_sackblock *r = &to->to_sackblocks[i]; |
| 2736 | |
| 2737 | r->rblk_start = ntohl(r->rblk_start); |
| 2738 | r->rblk_end = ntohl(r->rblk_end); |
| 2739 | } |
| 2740 | break; |
| 2741 | #ifdef TCP_SIGNATURE |
| 2742 | /* |
| 2743 | * XXX In order to reply to a host which has set the |
| 2744 | * TCP_SIGNATURE option in its initial SYN, we have to |
| 2745 | * record the fact that the option was observed here |
| 2746 | * for the syncache code to perform the correct response. |
| 2747 | */ |
| 2748 | case TCPOPT_SIGNATURE: |
| 2749 | if (optlen != TCPOLEN_SIGNATURE) |
| 2750 | continue; |
| 2751 | to->to_flags |= (TOF_SIGNATURE | TOF_SIGLEN); |
| 2752 | break; |
| 2753 | #endif /* TCP_SIGNATURE */ |
| 2754 | default: |
| 2755 | continue; |
| 2756 | } |
| 2757 | } |
| 2758 | } |
| 2759 | |
| 2760 | /* |
| 2761 | * Pull out of band byte out of a segment so |
| 2762 | * it doesn't appear in the user's data queue. |
| 2763 | * It is still reflected in the segment length for |
| 2764 | * sequencing purposes. |
| 2765 | * "off" is the delayed to be dropped hdrlen. |
| 2766 | */ |
| 2767 | static void |
| 2768 | tcp_pulloutofband(struct socket *so, struct tcphdr *th, struct mbuf *m, int off) |
| 2769 | { |
| 2770 | int cnt = off + th->th_urp - 1; |
| 2771 | |
| 2772 | while (cnt >= 0) { |
| 2773 | if (m->m_len > cnt) { |
| 2774 | char *cp = mtod(m, caddr_t) + cnt; |
| 2775 | struct tcpcb *tp = sototcpcb(so); |
| 2776 | |
| 2777 | tp->t_iobc = *cp; |
| 2778 | tp->t_oobflags |= TCPOOB_HAVEDATA; |
| 2779 | bcopy(cp + 1, cp, m->m_len - cnt - 1); |
| 2780 | m->m_len--; |
| 2781 | if (m->m_flags & M_PKTHDR) |
| 2782 | m->m_pkthdr.len--; |
| 2783 | return; |
| 2784 | } |
| 2785 | cnt -= m->m_len; |
| 2786 | m = m->m_next; |
| 2787 | if (m == 0) |
| 2788 | break; |
| 2789 | } |
| 2790 | panic("tcp_pulloutofband"); |
| 2791 | } |
| 2792 | |
| 2793 | /* |
| 2794 | * Collect new round-trip time estimate |
| 2795 | * and update averages and current timeout. |
| 2796 | */ |
| 2797 | static void |
| 2798 | tcp_xmit_timer(struct tcpcb *tp, int rtt) |
| 2799 | { |
| 2800 | int delta; |
| 2801 | |
| 2802 | tcpstat.tcps_rttupdated++; |
| 2803 | tp->t_rttupdated++; |
| 2804 | if (tp->t_srtt != 0) { |
| 2805 | /* |
| 2806 | * srtt is stored as fixed point with 5 bits after the |
| 2807 | * binary point (i.e., scaled by 8). The following magic |
| 2808 | * is equivalent to the smoothing algorithm in rfc793 with |
| 2809 | * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed |
| 2810 | * point). Adjust rtt to origin 0. |
| 2811 | */ |
| 2812 | delta = ((rtt - 1) << TCP_DELTA_SHIFT) |
| 2813 | - (tp->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT)); |
| 2814 | |
| 2815 | if ((tp->t_srtt += delta) <= 0) |
| 2816 | tp->t_srtt = 1; |
| 2817 | |
| 2818 | /* |
| 2819 | * We accumulate a smoothed rtt variance (actually, a |
| 2820 | * smoothed mean difference), then set the retransmit |
| 2821 | * timer to smoothed rtt + 4 times the smoothed variance. |
| 2822 | * rttvar is stored as fixed point with 4 bits after the |
| 2823 | * binary point (scaled by 16). The following is |
| 2824 | * equivalent to rfc793 smoothing with an alpha of .75 |
| 2825 | * (rttvar = rttvar*3/4 + |delta| / 4). This replaces |
| 2826 | * rfc793's wired-in beta. |
| 2827 | */ |
| 2828 | if (delta < 0) |
| 2829 | delta = -delta; |
| 2830 | delta -= tp->t_rttvar >> (TCP_RTTVAR_SHIFT - TCP_DELTA_SHIFT); |
| 2831 | if ((tp->t_rttvar += delta) <= 0) |
| 2832 | tp->t_rttvar = 1; |
| 2833 | if (tp->t_rttbest > tp->t_srtt + tp->t_rttvar) |
| 2834 | tp->t_rttbest = tp->t_srtt + tp->t_rttvar; |
| 2835 | } else { |
| 2836 | /* |
| 2837 | * No rtt measurement yet - use the unsmoothed rtt. |
| 2838 | * Set the variance to half the rtt (so our first |
| 2839 | * retransmit happens at 3*rtt). |
| 2840 | */ |
| 2841 | tp->t_srtt = rtt << TCP_RTT_SHIFT; |
| 2842 | tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1); |
| 2843 | tp->t_rttbest = tp->t_srtt + tp->t_rttvar; |
| 2844 | } |
| 2845 | tp->t_rtttime = 0; |
| 2846 | tp->t_rxtshift = 0; |
| 2847 | |
| 2848 | /* |
| 2849 | * the retransmit should happen at rtt + 4 * rttvar. |
| 2850 | * Because of the way we do the smoothing, srtt and rttvar |
| 2851 | * will each average +1/2 tick of bias. When we compute |
| 2852 | * the retransmit timer, we want 1/2 tick of rounding and |
| 2853 | * 1 extra tick because of +-1/2 tick uncertainty in the |
| 2854 | * firing of the timer. The bias will give us exactly the |
| 2855 | * 1.5 tick we need. But, because the bias is |
| 2856 | * statistical, we have to test that we don't drop below |
| 2857 | * the minimum feasible timer (which is 2 ticks). |
| 2858 | */ |
| 2859 | TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp), |
| 2860 | max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX); |
| 2861 | |
| 2862 | /* |
| 2863 | * We received an ack for a packet that wasn't retransmitted; |
| 2864 | * it is probably safe to discard any error indications we've |
| 2865 | * received recently. This isn't quite right, but close enough |
| 2866 | * for now (a route might have failed after we sent a segment, |
| 2867 | * and the return path might not be symmetrical). |
| 2868 | */ |
| 2869 | tp->t_softerror = 0; |
| 2870 | } |
| 2871 | |
| 2872 | /* |
| 2873 | * Determine a reasonable value for maxseg size. |
| 2874 | * If the route is known, check route for mtu. |
| 2875 | * If none, use an mss that can be handled on the outgoing |
| 2876 | * interface without forcing IP to fragment; if bigger than |
| 2877 | * an mbuf cluster (MCLBYTES), round down to nearest multiple of MCLBYTES |
| 2878 | * to utilize large mbufs. If no route is found, route has no mtu, |
| 2879 | * or the destination isn't local, use a default, hopefully conservative |
| 2880 | * size (usually 512 or the default IP max size, but no more than the mtu |
| 2881 | * of the interface), as we can't discover anything about intervening |
| 2882 | * gateways or networks. We also initialize the congestion/slow start |
| 2883 | * window to be a single segment if the destination isn't local. |
| 2884 | * While looking at the routing entry, we also initialize other path-dependent |
| 2885 | * parameters from pre-set or cached values in the routing entry. |
| 2886 | * |
| 2887 | * Also take into account the space needed for options that we |
| 2888 | * send regularly. Make maxseg shorter by that amount to assure |
| 2889 | * that we can send maxseg amount of data even when the options |
| 2890 | * are present. Store the upper limit of the length of options plus |
| 2891 | * data in maxopd. |
| 2892 | * |
| 2893 | * NOTE that this routine is only called when we process an incoming |
| 2894 | * segment, for outgoing segments only tcp_mssopt is called. |
| 2895 | */ |
| 2896 | void |
| 2897 | tcp_mss(struct tcpcb *tp, int offer) |
| 2898 | { |
| 2899 | struct rtentry *rt; |
| 2900 | struct ifnet *ifp; |
| 2901 | int rtt, mss; |
| 2902 | u_long bufsize; |
| 2903 | struct inpcb *inp = tp->t_inpcb; |
| 2904 | struct socket *so; |
| 2905 | #ifdef INET6 |
| 2906 | boolean_t isipv6 = ((inp->inp_vflag & INP_IPV6) ? TRUE : FALSE); |
| 2907 | size_t min_protoh = isipv6 ? |
| 2908 | sizeof(struct ip6_hdr) + sizeof(struct tcphdr) : |
| 2909 | sizeof(struct tcpiphdr); |
| 2910 | #else |
| 2911 | const boolean_t isipv6 = FALSE; |
| 2912 | const size_t min_protoh = sizeof(struct tcpiphdr); |
| 2913 | #endif |
| 2914 | |
| 2915 | if (isipv6) |
| 2916 | rt = tcp_rtlookup6(&inp->inp_inc); |
| 2917 | else |
| 2918 | rt = tcp_rtlookup(&inp->inp_inc); |
| 2919 | if (rt == NULL) { |
| 2920 | tp->t_maxopd = tp->t_maxseg = |
| 2921 | (isipv6 ? tcp_v6mssdflt : tcp_mssdflt); |
| 2922 | return; |
| 2923 | } |
| 2924 | ifp = rt->rt_ifp; |
| 2925 | so = inp->inp_socket; |
| 2926 | |
| 2927 | /* |
| 2928 | * Offer == 0 means that there was no MSS on the SYN segment, |
| 2929 | * in this case we use either the interface mtu or tcp_mssdflt. |
| 2930 | * |
| 2931 | * An offer which is too large will be cut down later. |
| 2932 | */ |
| 2933 | if (offer == 0) { |
| 2934 | if (isipv6) { |
| 2935 | if (in6_localaddr(&inp->in6p_faddr)) { |
| 2936 | offer = ND_IFINFO(rt->rt_ifp)->linkmtu - |
| 2937 | min_protoh; |
| 2938 | } else { |
| 2939 | offer = tcp_v6mssdflt; |
| 2940 | } |
| 2941 | } else { |
| 2942 | if (in_localaddr(inp->inp_faddr)) |
| 2943 | offer = ifp->if_mtu - min_protoh; |
| 2944 | else |
| 2945 | offer = tcp_mssdflt; |
| 2946 | } |
| 2947 | } |
| 2948 | |
| 2949 | /* |
| 2950 | * Prevent DoS attack with too small MSS. Round up |
| 2951 | * to at least minmss. |
| 2952 | * |
| 2953 | * Sanity check: make sure that maxopd will be large |
| 2954 | * enough to allow some data on segments even is the |
| 2955 | * all the option space is used (40bytes). Otherwise |
| 2956 | * funny things may happen in tcp_output. |
| 2957 | */ |
| 2958 | offer = max(offer, tcp_minmss); |
| 2959 | offer = max(offer, 64); |
| 2960 | |
| 2961 | rt->rt_rmx.rmx_mssopt = offer; |
| 2962 | |
| 2963 | /* |
| 2964 | * While we're here, check if there's an initial rtt |
| 2965 | * or rttvar. Convert from the route-table units |
| 2966 | * to scaled multiples of the slow timeout timer. |
| 2967 | */ |
| 2968 | if (tp->t_srtt == 0 && (rtt = rt->rt_rmx.rmx_rtt)) { |
| 2969 | /* |
| 2970 | * XXX the lock bit for RTT indicates that the value |
| 2971 | * is also a minimum value; this is subject to time. |
| 2972 | */ |
| 2973 | if (rt->rt_rmx.rmx_locks & RTV_RTT) |
| 2974 | tp->t_rttmin = rtt / (RTM_RTTUNIT / hz); |
| 2975 | tp->t_srtt = rtt / (RTM_RTTUNIT / (hz * TCP_RTT_SCALE)); |
| 2976 | tp->t_rttbest = tp->t_srtt + TCP_RTT_SCALE; |
| 2977 | tcpstat.tcps_usedrtt++; |
| 2978 | if (rt->rt_rmx.rmx_rttvar) { |
| 2979 | tp->t_rttvar = rt->rt_rmx.rmx_rttvar / |
| 2980 | (RTM_RTTUNIT / (hz * TCP_RTTVAR_SCALE)); |
| 2981 | tcpstat.tcps_usedrttvar++; |
| 2982 | } else { |
| 2983 | /* default variation is +- 1 rtt */ |
| 2984 | tp->t_rttvar = |
| 2985 | tp->t_srtt * TCP_RTTVAR_SCALE / TCP_RTT_SCALE; |
| 2986 | } |
| 2987 | TCPT_RANGESET(tp->t_rxtcur, |
| 2988 | ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1, |
| 2989 | tp->t_rttmin, TCPTV_REXMTMAX); |
| 2990 | } |
| 2991 | |
| 2992 | /* |
| 2993 | * if there's an mtu associated with the route, use it |
| 2994 | * else, use the link mtu. Take the smaller of mss or offer |
| 2995 | * as our final mss. |
| 2996 | */ |
| 2997 | if (rt->rt_rmx.rmx_mtu) { |
| 2998 | mss = rt->rt_rmx.rmx_mtu - min_protoh; |
| 2999 | } else { |
| 3000 | if (isipv6) |
| 3001 | mss = ND_IFINFO(rt->rt_ifp)->linkmtu - min_protoh; |
| 3002 | else |
| 3003 | mss = ifp->if_mtu - min_protoh; |
| 3004 | } |
| 3005 | mss = min(mss, offer); |
| 3006 | |
| 3007 | /* |
| 3008 | * maxopd stores the maximum length of data AND options |
| 3009 | * in a segment; maxseg is the amount of data in a normal |
| 3010 | * segment. We need to store this value (maxopd) apart |
| 3011 | * from maxseg, because now every segment carries options |
| 3012 | * and thus we normally have somewhat less data in segments. |
| 3013 | */ |
| 3014 | tp->t_maxopd = mss; |
| 3015 | |
| 3016 | if ((tp->t_flags & (TF_REQ_TSTMP | TF_NOOPT)) == TF_REQ_TSTMP && |
| 3017 | ((tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP)) |
| 3018 | mss -= TCPOLEN_TSTAMP_APPA; |
| 3019 | |
| 3020 | #if (MCLBYTES & (MCLBYTES - 1)) == 0 |
| 3021 | if (mss > MCLBYTES) |
| 3022 | mss &= ~(MCLBYTES-1); |
| 3023 | #else |
| 3024 | if (mss > MCLBYTES) |
| 3025 | mss = mss / MCLBYTES * MCLBYTES; |
| 3026 | #endif |
| 3027 | /* |
| 3028 | * If there's a pipesize, change the socket buffer |
| 3029 | * to that size. Make the socket buffers an integral |
| 3030 | * number of mss units; if the mss is larger than |
| 3031 | * the socket buffer, decrease the mss. |
| 3032 | */ |
| 3033 | #ifdef RTV_SPIPE |
| 3034 | if ((bufsize = rt->rt_rmx.rmx_sendpipe) == 0) |
| 3035 | #endif |
| 3036 | bufsize = so->so_snd.ssb_hiwat; |
| 3037 | if (bufsize < mss) |
| 3038 | mss = bufsize; |
| 3039 | else { |
| 3040 | bufsize = roundup(bufsize, mss); |
| 3041 | if (bufsize > sb_max) |
| 3042 | bufsize = sb_max; |
| 3043 | if (bufsize > so->so_snd.ssb_hiwat) |
| 3044 | ssb_reserve(&so->so_snd, bufsize, so, NULL); |
| 3045 | } |
| 3046 | tp->t_maxseg = mss; |
| 3047 | |
| 3048 | #ifdef RTV_RPIPE |
| 3049 | if ((bufsize = rt->rt_rmx.rmx_recvpipe) == 0) |
| 3050 | #endif |
| 3051 | bufsize = so->so_rcv.ssb_hiwat; |
| 3052 | if (bufsize > mss) { |
| 3053 | bufsize = roundup(bufsize, mss); |
| 3054 | if (bufsize > sb_max) |
| 3055 | bufsize = sb_max; |
| 3056 | if (bufsize > so->so_rcv.ssb_hiwat) { |
| 3057 | lwkt_gettoken(&so->so_rcv.ssb_token); |
| 3058 | ssb_reserve(&so->so_rcv, bufsize, so, NULL); |
| 3059 | lwkt_reltoken(&so->so_rcv.ssb_token); |
| 3060 | } |
| 3061 | } |
| 3062 | |
| 3063 | /* |
| 3064 | * Set the slow-start flight size depending on whether this |
| 3065 | * is a local network or not. |
| 3066 | */ |
| 3067 | if (tcp_do_rfc3390) |
| 3068 | tp->snd_cwnd = min(4 * mss, max(2 * mss, 4380)); |
| 3069 | else |
| 3070 | tp->snd_cwnd = mss; |
| 3071 | |
| 3072 | if (rt->rt_rmx.rmx_ssthresh) { |
| 3073 | /* |
| 3074 | * There's some sort of gateway or interface |
| 3075 | * buffer limit on the path. Use this to set |
| 3076 | * the slow start threshhold, but set the |
| 3077 | * threshold to no less than 2*mss. |
| 3078 | */ |
| 3079 | tp->snd_ssthresh = max(2 * mss, rt->rt_rmx.rmx_ssthresh); |
| 3080 | tcpstat.tcps_usedssthresh++; |
| 3081 | } |
| 3082 | } |
| 3083 | |
| 3084 | /* |
| 3085 | * Determine the MSS option to send on an outgoing SYN. |
| 3086 | */ |
| 3087 | int |
| 3088 | tcp_mssopt(struct tcpcb *tp) |
| 3089 | { |
| 3090 | struct rtentry *rt; |
| 3091 | #ifdef INET6 |
| 3092 | boolean_t isipv6 = |
| 3093 | ((tp->t_inpcb->inp_vflag & INP_IPV6) ? TRUE : FALSE); |
| 3094 | int min_protoh = isipv6 ? |
| 3095 | sizeof(struct ip6_hdr) + sizeof(struct tcphdr) : |
| 3096 | sizeof(struct tcpiphdr); |
| 3097 | #else |
| 3098 | const boolean_t isipv6 = FALSE; |
| 3099 | const size_t min_protoh = sizeof(struct tcpiphdr); |
| 3100 | #endif |
| 3101 | |
| 3102 | if (isipv6) |
| 3103 | rt = tcp_rtlookup6(&tp->t_inpcb->inp_inc); |
| 3104 | else |
| 3105 | rt = tcp_rtlookup(&tp->t_inpcb->inp_inc); |
| 3106 | if (rt == NULL) |
| 3107 | return (isipv6 ? tcp_v6mssdflt : tcp_mssdflt); |
| 3108 | |
| 3109 | return (rt->rt_ifp->if_mtu - min_protoh); |
| 3110 | } |
| 3111 | |
| 3112 | /* |
| 3113 | * When a partial ack arrives, force the retransmission of the |
| 3114 | * next unacknowledged segment. Do not exit Fast Recovery. |
| 3115 | * |
| 3116 | * Implement the Slow-but-Steady variant of NewReno by restarting the |
| 3117 | * the retransmission timer. Turn it off here so it can be restarted |
| 3118 | * later in tcp_output(). |
| 3119 | */ |
| 3120 | static void |
| 3121 | tcp_newreno_partial_ack(struct tcpcb *tp, struct tcphdr *th, int acked) |
| 3122 | { |
| 3123 | tcp_seq old_snd_nxt = tp->snd_nxt; |
| 3124 | u_long ocwnd = tp->snd_cwnd; |
| 3125 | |
| 3126 | tcp_callout_stop(tp, tp->tt_rexmt); |
| 3127 | tp->t_rtttime = 0; |
| 3128 | tp->snd_nxt = th->th_ack; |
| 3129 | /* Set snd_cwnd to one segment beyond acknowledged offset. */ |
| 3130 | tp->snd_cwnd = tp->t_maxseg; |
| 3131 | tp->t_flags |= TF_ACKNOW; |
| 3132 | tcp_output(tp); |
| 3133 | if (SEQ_GT(old_snd_nxt, tp->snd_nxt)) |
| 3134 | tp->snd_nxt = old_snd_nxt; |
| 3135 | /* partial window deflation */ |
| 3136 | if (ocwnd > acked) |
| 3137 | tp->snd_cwnd = ocwnd - acked + tp->t_maxseg; |
| 3138 | else |
| 3139 | tp->snd_cwnd = tp->t_maxseg; |
| 3140 | } |
| 3141 | |
| 3142 | /* |
| 3143 | * In contrast to the Slow-but-Steady NewReno variant, |
| 3144 | * we do not reset the retransmission timer for SACK retransmissions, |
| 3145 | * except when retransmitting snd_una. |
| 3146 | */ |
| 3147 | static void |
| 3148 | tcp_sack_rexmt(struct tcpcb *tp, struct tcphdr *th) |
| 3149 | { |
| 3150 | uint32_t pipe, seglen; |
| 3151 | tcp_seq nextrexmt; |
| 3152 | boolean_t lostdup; |
| 3153 | tcp_seq old_snd_nxt = tp->snd_nxt; |
| 3154 | u_long ocwnd = tp->snd_cwnd; |
| 3155 | int nseg = 0; /* consecutive new segments */ |
| 3156 | #define MAXBURST 4 /* limit burst of new packets on partial ack */ |
| 3157 | |
| 3158 | tp->t_rtttime = 0; |
| 3159 | pipe = tcp_sack_compute_pipe(tp); |
| 3160 | while ((tcp_seq_diff_t)(ocwnd - pipe) >= (tcp_seq_diff_t)tp->t_maxseg && |
| 3161 | (!tcp_do_smartsack || nseg < MAXBURST) && |
| 3162 | tcp_sack_nextseg(tp, &nextrexmt, &seglen, &lostdup)) { |
| 3163 | uint32_t sent; |
| 3164 | tcp_seq old_snd_max; |
| 3165 | int error; |
| 3166 | |
| 3167 | if (nextrexmt == tp->snd_max) |
| 3168 | ++nseg; |
| 3169 | tp->snd_nxt = nextrexmt; |
| 3170 | tp->snd_cwnd = nextrexmt - tp->snd_una + seglen; |
| 3171 | old_snd_max = tp->snd_max; |
| 3172 | if (nextrexmt == tp->snd_una) |
| 3173 | tcp_callout_stop(tp, tp->tt_rexmt); |
| 3174 | error = tcp_output(tp); |
| 3175 | if (error != 0) |
| 3176 | break; |
| 3177 | sent = tp->snd_nxt - nextrexmt; |
| 3178 | if (sent <= 0) |
| 3179 | break; |
| 3180 | if (!lostdup) |
| 3181 | pipe += sent; |
| 3182 | tcpstat.tcps_sndsackpack++; |
| 3183 | tcpstat.tcps_sndsackbyte += sent; |
| 3184 | if (SEQ_LT(nextrexmt, old_snd_max) && |
| 3185 | SEQ_LT(tp->rexmt_high, tp->snd_nxt)) |
| 3186 | tp->rexmt_high = seq_min(tp->snd_nxt, old_snd_max); |
| 3187 | } |
| 3188 | if (SEQ_GT(old_snd_nxt, tp->snd_nxt)) |
| 3189 | tp->snd_nxt = old_snd_nxt; |
| 3190 | tp->snd_cwnd = ocwnd; |
| 3191 | } |