arcmsr.4: Add some more cards which are supported by this driver.
[dragonfly.git] / sys / netinet / tcp_input.c
CommitLineData
984263bc 1/*
66d6c637
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2 * Copyright (c) 2002, 2003, 2004 Jeffrey M. Hsu. All rights reserved.
3 * Copyright (c) 2002, 2003, 2004 The DragonFly Project. All rights reserved.
95b22adf 4 *
66d6c637
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5 * This code is derived from software contributed to The DragonFly Project
6 * by Jeffrey M. Hsu.
95b22adf 7 *
66d6c637
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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.
95b22adf 19 *
66d6c637
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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
66d6c637 34/*
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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 $
5de23090 68 * $DragonFly: src/sys/netinet/tcp_input.c,v 1.68 2008/08/22 09:14:17 sephe Exp $
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69 */
70
71#include "opt_ipfw.h" /* for ipfw_fwd */
72#include "opt_inet6.h"
73#include "opt_ipsec.h"
74#include "opt_tcpdebug.h"
75#include "opt_tcp_input.h"
76
77#include <sys/param.h>
78#include <sys/systm.h>
79#include <sys/kernel.h>
80#include <sys/sysctl.h>
81#include <sys/malloc.h>
82#include <sys/mbuf.h>
83#include <sys/proc.h> /* for proc0 declaration */
84#include <sys/protosw.h>
85#include <sys/socket.h>
86#include <sys/socketvar.h>
87#include <sys/syslog.h>
3f9db7f8 88#include <sys/in_cksum.h>
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89
90#include <machine/cpu.h> /* before tcp_seq.h, for tcp_random18() */
a00138cb 91#include <machine/stdarg.h>
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92
93#include <net/if.h>
94#include <net/route.h>
95
96#include <netinet/in.h>
97#include <netinet/in_systm.h>
98#include <netinet/ip.h>
95b22adf 99#include <netinet/ip_icmp.h> /* for ICMP_BANDLIM */
984263bc 100#include <netinet/in_var.h>
95b22adf 101#include <netinet/icmp_var.h> /* for ICMP_BANDLIM */
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102#include <netinet/in_pcb.h>
103#include <netinet/ip_var.h>
104#include <netinet/ip6.h>
105#include <netinet/icmp6.h>
106#include <netinet6/nd6.h>
107#include <netinet6/ip6_var.h>
108#include <netinet6/in6_pcb.h>
109#include <netinet/tcp.h>
110#include <netinet/tcp_fsm.h>
111#include <netinet/tcp_seq.h>
112#include <netinet/tcp_timer.h>
a48c5dd5 113#include <netinet/tcp_timer2.h>
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114#include <netinet/tcp_var.h>
115#include <netinet6/tcp6_var.h>
116#include <netinet/tcpip.h>
95b22adf 117
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118#ifdef TCPDEBUG
119#include <netinet/tcp_debug.h>
120
95b22adf 121u_char tcp_saveipgen[40]; /* the size must be of max ip header, now IPv6 */
984263bc 122struct tcphdr tcp_savetcp;
95b22adf 123#endif
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124
125#ifdef FAST_IPSEC
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126#include <netproto/ipsec/ipsec.h>
127#include <netproto/ipsec/ipsec6.h>
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128#endif
129
130#ifdef IPSEC
131#include <netinet6/ipsec.h>
132#include <netinet6/ipsec6.h>
d2438d69 133#include <netproto/key/key.h>
95b22adf 134#endif
984263bc 135
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136MALLOC_DEFINE(M_TSEGQ, "tseg_qent", "TCP segment queue entry");
137
984263bc 138static int log_in_vain = 0;
d24ce1dc 139SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_in_vain, CTLFLAG_RW,
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140 &log_in_vain, 0, "Log all incoming TCP connections");
141
142static int blackhole = 0;
143SYSCTL_INT(_net_inet_tcp, OID_AUTO, blackhole, CTLFLAG_RW,
144 &blackhole, 0, "Do not send RST when dropping refused connections");
145
146int tcp_delack_enabled = 1;
d24ce1dc
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147SYSCTL_INT(_net_inet_tcp, OID_AUTO, delayed_ack, CTLFLAG_RW,
148 &tcp_delack_enabled, 0,
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149 "Delay ACK to try and piggyback it onto a data packet");
150
151#ifdef TCP_DROP_SYNFIN
152static int drop_synfin = 0;
153SYSCTL_INT(_net_inet_tcp, OID_AUTO, drop_synfin, CTLFLAG_RW,
154 &drop_synfin, 0, "Drop TCP packets with SYN+FIN set");
155#endif
156
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157static int tcp_do_limitedtransmit = 1;
158SYSCTL_INT(_net_inet_tcp, OID_AUTO, limitedtransmit, CTLFLAG_RW,
159 &tcp_do_limitedtransmit, 0, "Enable RFC 3042 (Limited Transmit)");
160
91489f6b 161static int tcp_do_early_retransmit = 1;
8819433a
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162SYSCTL_INT(_net_inet_tcp, OID_AUTO, earlyretransmit, CTLFLAG_RW,
163 &tcp_do_early_retransmit, 0, "Early retransmit");
164
8acdb67c 165int tcp_aggregate_acks = 1;
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166SYSCTL_INT(_net_inet_tcp, OID_AUTO, aggregate_acks, CTLFLAG_RW,
167 &tcp_aggregate_acks, 0, "Aggregate built-up acks into one ack");
168
8d573eef 169int tcp_do_rfc3390 = 1;
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170SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3390, CTLFLAG_RW,
171 &tcp_do_rfc3390, 0,
172 "Enable RFC 3390 (Increasing TCP's Initial Congestion Window)");
173
efd4b327
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174static int tcp_do_eifel_detect = 1;
175SYSCTL_INT(_net_inet_tcp, OID_AUTO, eifel, CTLFLAG_RW,
176 &tcp_do_eifel_detect, 0, "Eifel detection algorithm (RFC 3522)");
177
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178static int tcp_do_abc = 1;
179SYSCTL_INT(_net_inet_tcp, OID_AUTO, abc, CTLFLAG_RW,
180 &tcp_do_abc, 0,
181 "TCP Appropriate Byte Counting (RFC 3465)");
182
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183/*
184 * Define as tunable for easy testing with SACK on and off.
185 * Warning: do not change setting in the middle of an existing active TCP flow,
186 * else strange things might happen to that flow.
187 */
6e5bbdda 188int tcp_do_sack = 1;
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189SYSCTL_INT(_net_inet_tcp, OID_AUTO, sack, CTLFLAG_RW,
190 &tcp_do_sack, 0, "Enable SACK Algorithms");
191
192int tcp_do_smartsack = 1;
193SYSCTL_INT(_net_inet_tcp, OID_AUTO, smartsack, CTLFLAG_RW,
194 &tcp_do_smartsack, 0, "Enable Smart SACK Algorithms");
195
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196SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass, CTLFLAG_RW, 0,
197 "TCP Segment Reassembly Queue");
198
199int tcp_reass_maxseg = 0;
200SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RD,
201 &tcp_reass_maxseg, 0,
202 "Global maximum number of TCP Segments in Reassembly Queue");
203
204int tcp_reass_qsize = 0;
205SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, cursegments, CTLFLAG_RD,
206 &tcp_reass_qsize, 0,
207 "Global number of TCP Segments currently in Reassembly Queue");
208
209static int tcp_reass_overflows = 0;
210SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, overflows, CTLFLAG_RD,
211 &tcp_reass_overflows, 0,
212 "Global number of TCP Segment Reassembly Queue Overflows");
213
5b0b9fa5
PA
214int tcp_do_autorcvbuf = 1;
215SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_auto, CTLFLAG_RW,
216 &tcp_do_autorcvbuf, 0, "Enable automatic receive buffer sizing");
217
218int tcp_autorcvbuf_inc = 16*1024;
219SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_inc, CTLFLAG_RW,
220 &tcp_autorcvbuf_inc, 0,
221 "Incrementor step size of automatic receive buffer");
222
46e92930 223int tcp_autorcvbuf_max = 2*1024*1024;
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PA
224SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_max, CTLFLAG_RW,
225 &tcp_autorcvbuf_max, 0, "Max size of automatic receive buffer");
226
227
95b22adf 228static void tcp_dooptions(struct tcpopt *, u_char *, int, boolean_t);
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229static void tcp_pulloutofband(struct socket *,
230 struct tcphdr *, struct mbuf *, int);
231static int tcp_reass(struct tcpcb *, struct tcphdr *, int *,
232 struct mbuf *);
233static void tcp_xmit_timer(struct tcpcb *, int);
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234static void tcp_newreno_partial_ack(struct tcpcb *, struct tcphdr *, int);
235static void tcp_sack_rexmt(struct tcpcb *, struct tcphdr *);
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236
237/* Neighbor Discovery, Neighbor Unreachability Detection Upper layer hint. */
238#ifdef INET6
239#define ND6_HINT(tp) \
240do { \
241 if ((tp) && (tp)->t_inpcb && \
61896e3c 242 ((tp)->t_inpcb->inp_vflag & INP_IPV6) && \
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243 (tp)->t_inpcb->in6p_route.ro_rt) \
244 nd6_nud_hint((tp)->t_inpcb->in6p_route.ro_rt, NULL, 0); \
245} while (0)
246#else
247#define ND6_HINT(tp)
248#endif
249
250/*
251 * Indicate whether this ack should be delayed. We can delay the ack if
252 * - delayed acks are enabled and
253 * - there is no delayed ack timer in progress and
254 * - our last ack wasn't a 0-sized window. We never want to delay
255 * the ack that opens up a 0-sized window.
256 */
257#define DELAY_ACK(tp) \
a48c5dd5 258 (tcp_delack_enabled && !tcp_callout_pending(tp, tp->tt_delack) && \
61896e3c 259 !(tp->t_flags & TF_RXWIN0SENT))
984263bc 260
df9d7670
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261#define acceptable_window_update(tp, th, tiwin) \
262 (SEQ_LT(tp->snd_wl1, th->th_seq) || \
263 (tp->snd_wl1 == th->th_seq && \
264 (SEQ_LT(tp->snd_wl2, th->th_ack) || \
265 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))
266
984263bc 267static int
95b22adf 268tcp_reass(struct tcpcb *tp, struct tcphdr *th, int *tlenp, struct mbuf *m)
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269{
270 struct tseg_qent *q;
271 struct tseg_qent *p = NULL;
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272 struct tseg_qent *te;
273 struct socket *so = tp->t_inpcb->inp_socket;
274 int flags;
275
276 /*
61896e3c 277 * Call with th == NULL after become established to
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278 * force pre-ESTABLISHED data up to user socket.
279 */
61896e3c 280 if (th == NULL)
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281 goto present;
282
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283 /*
284 * Limit the number of segments in the reassembly queue to prevent
285 * holding on to too many segments (and thus running out of mbufs).
286 * Make sure to let the missing segment through which caused this
287 * queue. Always keep one global queue entry spare to be able to
288 * process the missing segment.
289 */
290 if (th->th_seq != tp->rcv_nxt &&
291 tcp_reass_qsize + 1 >= tcp_reass_maxseg) {
292 tcp_reass_overflows++;
293 tcpstat.tcps_rcvmemdrop++;
294 m_freem(m);
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295 /* no SACK block to report */
296 tp->reportblk.rblk_start = tp->reportblk.rblk_end;
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RG
297 return (0);
298 }
299
ba4e3dbe 300 /* Allocate a new queue entry. */
984263bc 301 MALLOC(te, struct tseg_qent *, sizeof(struct tseg_qent), M_TSEGQ,
ba4e3dbe 302 M_INTWAIT | M_NULLOK);
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303 if (te == NULL) {
304 tcpstat.tcps_rcvmemdrop++;
305 m_freem(m);
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306 /* no SACK block to report */
307 tp->reportblk.rblk_start = tp->reportblk.rblk_end;
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308 return (0);
309 }
3edf7c37 310 tcp_reass_qsize++;
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311
312 /*
313 * Find a segment which begins after this one does.
314 */
315 LIST_FOREACH(q, &tp->t_segq, tqe_q) {
316 if (SEQ_GT(q->tqe_th->th_seq, th->th_seq))
317 break;
318 p = q;
319 }
320
321 /*
322 * If there is a preceding segment, it may provide some of
323 * our data already. If so, drop the data from the incoming
324 * segment. If it provides all of our data, drop us.
325 */
326 if (p != NULL) {
76cf5e41 327 tcp_seq_diff_t i;
91489f6b 328
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329 /* conversion to int (in i) handles seq wraparound */
330 i = p->tqe_th->th_seq + p->tqe_len - th->th_seq;
91489f6b
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331 if (i > 0) { /* overlaps preceding segment */
332 tp->t_flags |= (TF_DUPSEG | TF_ENCLOSESEG);
333 /* enclosing block starts w/ preceding segment */
334 tp->encloseblk.rblk_start = p->tqe_th->th_seq;
984263bc 335 if (i >= *tlenp) {
91489f6b
JH
336 /* preceding encloses incoming segment */
337 tp->encloseblk.rblk_end = p->tqe_th->th_seq +
338 p->tqe_len;
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339 tcpstat.tcps_rcvduppack++;
340 tcpstat.tcps_rcvdupbyte += *tlenp;
341 m_freem(m);
efda3bd0 342 kfree(te, M_TSEGQ);
3edf7c37 343 tcp_reass_qsize--;
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344 /*
345 * Try to present any queued data
346 * at the left window edge to the user.
347 * This is needed after the 3-WHS
348 * completes.
349 */
350 goto present; /* ??? */
351 }
352 m_adj(m, i);
353 *tlenp -= i;
354 th->th_seq += i;
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JH
355 /* incoming segment end is enclosing block end */
356 tp->encloseblk.rblk_end = th->th_seq + *tlenp +
357 ((th->th_flags & TH_FIN) != 0);
358 /* trim end of reported D-SACK block */
359 tp->reportblk.rblk_end = th->th_seq;
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360 }
361 }
362 tcpstat.tcps_rcvoopack++;
363 tcpstat.tcps_rcvoobyte += *tlenp;
364
365 /*
366 * While we overlap succeeding segments trim them or,
367 * if they are completely covered, dequeue them.
368 */
369 while (q) {
76cf5e41 370 tcp_seq_diff_t i = (th->th_seq + *tlenp) - q->tqe_th->th_seq;
91489f6b
JH
371 tcp_seq qend = q->tqe_th->th_seq + q->tqe_len;
372 struct tseg_qent *nq;
373
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374 if (i <= 0)
375 break;
91489f6b
JH
376 if (!(tp->t_flags & TF_DUPSEG)) { /* first time through */
377 tp->t_flags |= (TF_DUPSEG | TF_ENCLOSESEG);
378 tp->encloseblk = tp->reportblk;
379 /* report trailing duplicate D-SACK segment */
380 tp->reportblk.rblk_start = q->tqe_th->th_seq;
381 }
382 if ((tp->t_flags & TF_ENCLOSESEG) &&
383 SEQ_GT(qend, tp->encloseblk.rblk_end)) {
384 /* extend enclosing block if one exists */
385 tp->encloseblk.rblk_end = qend;
386 }
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MD
387 if (i < q->tqe_len) {
388 q->tqe_th->th_seq += i;
389 q->tqe_len -= i;
390 m_adj(q->tqe_m, i);
391 break;
392 }
393
394 nq = LIST_NEXT(q, tqe_q);
395 LIST_REMOVE(q, tqe_q);
396 m_freem(q->tqe_m);
efda3bd0 397 kfree(q, M_TSEGQ);
3edf7c37 398 tcp_reass_qsize--;
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399 q = nq;
400 }
401
402 /* Insert the new segment queue entry into place. */
403 te->tqe_m = m;
404 te->tqe_th = th;
405 te->tqe_len = *tlenp;
406
91489f6b
JH
407 /* check if can coalesce with following segment */
408 if (q != NULL && (th->th_seq + *tlenp == q->tqe_th->th_seq)) {
409 tcp_seq tend = te->tqe_th->th_seq + te->tqe_len;
410
411 te->tqe_len += q->tqe_len;
a174690a 412 if (q->tqe_th->th_flags & TH_FIN)
f16f8cc3 413 te->tqe_th->th_flags |= TH_FIN;
91489f6b
JH
414 m_cat(te->tqe_m, q->tqe_m);
415 tp->encloseblk.rblk_end = tend;
416 /*
417 * When not reporting a duplicate segment, use
418 * the larger enclosing block as the SACK block.
419 */
420 if (!(tp->t_flags & TF_DUPSEG))
421 tp->reportblk.rblk_end = tend;
422 LIST_REMOVE(q, tqe_q);
efda3bd0 423 kfree(q, M_TSEGQ);
91489f6b
JH
424 tcp_reass_qsize--;
425 }
426
984263bc
MD
427 if (p == NULL) {
428 LIST_INSERT_HEAD(&tp->t_segq, te, tqe_q);
429 } else {
91489f6b
JH
430 /* check if can coalesce with preceding segment */
431 if (p->tqe_th->th_seq + p->tqe_len == th->th_seq) {
a174690a
JH
432 p->tqe_len += te->tqe_len;
433 m_cat(p->tqe_m, te->tqe_m);
91489f6b
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434 tp->encloseblk.rblk_start = p->tqe_th->th_seq;
435 /*
436 * When not reporting a duplicate segment, use
437 * the larger enclosing block as the SACK block.
438 */
439 if (!(tp->t_flags & TF_DUPSEG))
440 tp->reportblk.rblk_start = p->tqe_th->th_seq;
efda3bd0 441 kfree(te, M_TSEGQ);
a174690a 442 tcp_reass_qsize--;
91489f6b
JH
443 } else
444 LIST_INSERT_AFTER(p, te, tqe_q);
984263bc
MD
445 }
446
447present:
448 /*
449 * Present data to user, advancing rcv_nxt through
450 * completed sequence space.
451 */
452 if (!TCPS_HAVEESTABLISHED(tp->t_state))
453 return (0);
454 q = LIST_FIRST(&tp->t_segq);
61896e3c 455 if (q == NULL || q->tqe_th->th_seq != tp->rcv_nxt)
984263bc 456 return (0);
91489f6b
JH
457 tp->rcv_nxt += q->tqe_len;
458 if (!(tp->t_flags & TF_DUPSEG)) {
459 /* no SACK block to report since ACK advanced */
460 tp->reportblk.rblk_start = tp->reportblk.rblk_end;
461 }
462 /* no enclosing block to report since ACK advanced */
463 tp->t_flags &= ~TF_ENCLOSESEG;
464 flags = q->tqe_th->th_flags & TH_FIN;
465 LIST_REMOVE(q, tqe_q);
466 KASSERT(LIST_EMPTY(&tp->t_segq) ||
467 LIST_FIRST(&tp->t_segq)->tqe_th->th_seq != tp->rcv_nxt,
468 ("segment not coalesced"));
469 if (so->so_state & SS_CANTRCVMORE)
470 m_freem(q->tqe_m);
471 else
6d49aa6f 472 ssb_appendstream(&so->so_rcv, q->tqe_m);
efda3bd0 473 kfree(q, M_TSEGQ);
91489f6b 474 tcp_reass_qsize--;
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MD
475 ND6_HINT(tp);
476 sorwakeup(so);
477 return (flags);
478}
479
480/*
481 * TCP input routine, follows pages 65-76 of the
482 * protocol specification dated September, 1981 very closely.
483 */
484#ifdef INET6
485int
95b22adf 486tcp6_input(struct mbuf **mp, int *offp, int proto)
984263bc 487{
2256ba69 488 struct mbuf *m = *mp;
984263bc
MD
489 struct in6_ifaddr *ia6;
490
491 IP6_EXTHDR_CHECK(m, *offp, sizeof(struct tcphdr), IPPROTO_DONE);
492
493 /*
494 * draft-itojun-ipv6-tcp-to-anycast
495 * better place to put this in?
496 */
497 ia6 = ip6_getdstifaddr(m);
d24ce1dc 498 if (ia6 && (ia6->ia6_flags & IN6_IFF_ANYCAST)) {
984263bc
MD
499 struct ip6_hdr *ip6;
500
501 ip6 = mtod(m, struct ip6_hdr *);
502 icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR,
f23061d4 503 offsetof(struct ip6_hdr, ip6_dst));
d24ce1dc 504 return (IPPROTO_DONE);
984263bc
MD
505 }
506
507 tcp_input(m, *offp, proto);
d24ce1dc 508 return (IPPROTO_DONE);
984263bc
MD
509}
510#endif
511
512void
a00138cb 513tcp_input(struct mbuf *m, ...)
984263bc 514{
a00138cb
JS
515 __va_list ap;
516 int off0, proto;
2256ba69
RG
517 struct tcphdr *th;
518 struct ip *ip = NULL;
519 struct ipovly *ipov;
520 struct inpcb *inp = NULL;
984263bc
MD
521 u_char *optp = NULL;
522 int optlen = 0;
523 int len, tlen, off;
524 int drop_hdrlen;
2256ba69
RG
525 struct tcpcb *tp = NULL;
526 int thflags;
984263bc 527 struct socket *so = 0;
61896e3c
JH
528 int todrop, acked;
529 boolean_t ourfinisacked, needoutput = FALSE;
984263bc 530 u_long tiwin;
61896e3c 531 int recvwin;
984263bc 532 struct tcpopt to; /* options in this segment */
984263bc
MD
533 struct sockaddr_in *next_hop = NULL;
534 int rstreason; /* For badport_bandlim accounting purposes */
d371a63a 535 int cpu;
984263bc
MD
536 struct ip6_hdr *ip6 = NULL;
537#ifdef INET6
d24ce1dc 538 boolean_t isipv6;
984263bc 539#else
d24ce1dc 540 const boolean_t isipv6 = FALSE;
984263bc
MD
541#endif
542#ifdef TCPDEBUG
543 short ostate = 0;
544#endif
545
a00138cb
JS
546 __va_start(ap, m);
547 off0 = __va_arg(ap, int);
548 proto = __va_arg(ap, int);
549 __va_end(ap);
550
d24ce1dc
JH
551 tcpstat.tcps_rcvtotal++;
552
5de23090
SZ
553 if (m->m_pkthdr.fw_flags & IPFORWARD_MBUF_TAGGED) {
554 struct m_tag *mtag;
555
556 mtag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL);
557 KKASSERT(mtag != NULL);
558 next_hop = m_tag_data(mtag);
984263bc 559 }
d24ce1dc 560
984263bc 561#ifdef INET6
d24ce1dc 562 isipv6 = (mtod(m, struct ip *)->ip_v == 6) ? TRUE : FALSE;
984263bc 563#endif
984263bc
MD
564
565 if (isipv6) {
566 /* IP6_EXTHDR_CHECK() is already done at tcp6_input() */
567 ip6 = mtod(m, struct ip6_hdr *);
407e896e 568 tlen = (sizeof *ip6) + ntohs(ip6->ip6_plen) - off0;
984263bc
MD
569 if (in6_cksum(m, IPPROTO_TCP, off0, tlen)) {
570 tcpstat.tcps_rcvbadsum++;
571 goto drop;
572 }
573 th = (struct tcphdr *)((caddr_t)ip6 + off0);
574
575 /*
576 * Be proactive about unspecified IPv6 address in source.
577 * As we use all-zero to indicate unbounded/unconnected pcb,
578 * unspecified IPv6 address can be used to confuse us.
579 *
580 * Note that packets with unspecified IPv6 destination is
581 * already dropped in ip6_input.
582 */
583 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) {
584 /* XXX stat */
585 goto drop;
586 }
587 } else {
588 /*
589 * Get IP and TCP header together in first mbuf.
590 * Note: IP leaves IP header in first mbuf.
591 */
592 if (off0 > sizeof(struct ip)) {
bddf0751 593 ip_stripoptions(m);
984263bc
MD
594 off0 = sizeof(struct ip);
595 }
55d829f8
JH
596 /* already checked and pulled up in ip_demux() */
597 KASSERT(m->m_len >= sizeof(struct tcpiphdr),
61896e3c 598 ("TCP header not in one mbuf: m->m_len %d", m->m_len));
984263bc
MD
599 ip = mtod(m, struct ip *);
600 ipov = (struct ipovly *)ip;
601 th = (struct tcphdr *)((caddr_t)ip + off0);
602 tlen = ip->ip_len;
603
604 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) {
605 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR)
606 th->th_sum = m->m_pkthdr.csum_data;
607 else
608 th->th_sum = in_pseudo(ip->ip_src.s_addr,
609 ip->ip_dst.s_addr,
610 htonl(m->m_pkthdr.csum_data +
611 ip->ip_len +
612 IPPROTO_TCP));
613 th->th_sum ^= 0xffff;
614 } else {
615 /*
616 * Checksum extended TCP header and data.
617 */
618 len = sizeof(struct ip) + tlen;
407e896e 619 bzero(ipov->ih_x1, sizeof ipov->ih_x1);
984263bc
MD
620 ipov->ih_len = (u_short)tlen;
621 ipov->ih_len = htons(ipov->ih_len);
622 th->th_sum = in_cksum(m, len);
623 }
624 if (th->th_sum) {
625 tcpstat.tcps_rcvbadsum++;
626 goto drop;
627 }
628#ifdef INET6
629 /* Re-initialization for later version check */
630 ip->ip_v = IPVERSION;
631#endif
632 }
633
634 /*
635 * Check that TCP offset makes sense,
636 * pull out TCP options and adjust length. XXX
637 */
638 off = th->th_off << 2;
55d829f8
JH
639 /* already checked and pulled up in ip_demux() */
640 KASSERT(off >= sizeof(struct tcphdr) && off <= tlen,
61896e3c 641 ("bad TCP data offset %d (tlen %d)", off, tlen));
984263bc
MD
642 tlen -= off; /* tlen is used instead of ti->ti_len */
643 if (off > sizeof(struct tcphdr)) {
644 if (isipv6) {
645 IP6_EXTHDR_CHECK(m, off0, off, );
646 ip6 = mtod(m, struct ip6_hdr *);
647 th = (struct tcphdr *)((caddr_t)ip6 + off0);
648 } else {
55d829f8
JH
649 /* already pulled up in ip_demux() */
650 KASSERT(m->m_len >= sizeof(struct ip) + off,
61896e3c
JH
651 ("TCP header and options not in one mbuf: "
652 "m_len %d, off %d", m->m_len, off));
984263bc
MD
653 }
654 optlen = off - sizeof(struct tcphdr);
655 optp = (u_char *)(th + 1);
656 }
657 thflags = th->th_flags;
658
659#ifdef TCP_DROP_SYNFIN
660 /*
661 * If the drop_synfin option is enabled, drop all packets with
662 * both the SYN and FIN bits set. This prevents e.g. nmap from
663 * identifying the TCP/IP stack.
664 *
665 * This is a violation of the TCP specification.
666 */
61896e3c 667 if (drop_synfin && (thflags & (TH_SYN | TH_FIN)) == (TH_SYN | TH_FIN))
984263bc
MD
668 goto drop;
669#endif
670
671 /*
672 * Convert TCP protocol specific fields to host format.
673 */
674 th->th_seq = ntohl(th->th_seq);
675 th->th_ack = ntohl(th->th_ack);
676 th->th_win = ntohs(th->th_win);
677 th->th_urp = ntohs(th->th_urp);
678
679 /*
d24ce1dc 680 * Delay dropping TCP, IP headers, IPv6 ext headers, and TCP options,
984263bc
MD
681 * until after ip6_savecontrol() is called and before other functions
682 * which don't want those proto headers.
683 * Because ip6_savecontrol() is going to parse the mbuf to
684 * search for data to be passed up to user-land, it wants mbuf
685 * parameters to be unchanged.
686 * XXX: the call of ip6_savecontrol() has been obsoleted based on
687 * latest version of the advanced API (20020110).
688 */
689 drop_hdrlen = off0 + off;
690
691 /*
692 * Locate pcb for segment.
693 */
694findpcb:
695 /* IPFIREWALL_FORWARD section */
d24ce1dc 696 if (next_hop != NULL && !isipv6) { /* IPv6 support is not there yet */
984263bc
MD
697 /*
698 * Transparently forwarded. Pretend to be the destination.
d24ce1dc 699 * already got one like this?
984263bc 700 */
6ca1a1cd 701 cpu = mycpu->gd_cpuid;
6ca1a1cd 702 inp = in_pcblookup_hash(&tcbinfo[cpu],
d371a63a 703 ip->ip_src, th->th_sport,
984263bc
MD
704 ip->ip_dst, th->th_dport,
705 0, m->m_pkthdr.rcvif);
706 if (!inp) {
83be63fe
JH
707 /*
708 * It's new. Try to find the ambushing socket.
709 */
710
711 /*
712 * The rest of the ipfw code stores the port in
713 * host order. XXX
714 * (The IP address is still in network order.)
715 */
716 in_port_t dport = next_hop->sin_port ?
717 htons(next_hop->sin_port) :
718 th->th_dport;
719
d371a63a 720 cpu = tcp_addrcpu(ip->ip_src.s_addr, th->th_sport,
83be63fe 721 next_hop->sin_addr.s_addr, dport);
d371a63a 722 inp = in_pcblookup_hash(&tcbinfo[cpu],
984263bc 723 ip->ip_src, th->th_sport,
83be63fe 724 next_hop->sin_addr, dport,
984263bc
MD
725 1, m->m_pkthdr.rcvif);
726 }
727 } else {
6ca1a1cd 728 if (isipv6) {
d371a63a 729 inp = in6_pcblookup_hash(&tcbinfo[0],
984263bc
MD
730 &ip6->ip6_src, th->th_sport,
731 &ip6->ip6_dst, th->th_dport,
732 1, m->m_pkthdr.rcvif);
6ca1a1cd 733 } else {
6ca1a1cd 734 cpu = mycpu->gd_cpuid;
6ca1a1cd 735 inp = in_pcblookup_hash(&tcbinfo[cpu],
984263bc
MD
736 ip->ip_src, th->th_sport,
737 ip->ip_dst, th->th_dport,
738 1, m->m_pkthdr.rcvif);
6ca1a1cd 739 }
984263bc 740 }
984263bc
MD
741
742 /*
743 * If the state is CLOSED (i.e., TCB does not exist) then
744 * all data in the incoming segment is discarded.
745 * If the TCB exists but is in CLOSED state, it is embryonic,
746 * but should either do a listen or a connect soon.
747 */
748 if (inp == NULL) {
749 if (log_in_vain) {
750#ifdef INET6
751 char dbuf[INET6_ADDRSTRLEN+2], sbuf[INET6_ADDRSTRLEN+2];
752#else
1141eb20
JH
753 char dbuf[sizeof "aaa.bbb.ccc.ddd"];
754 char sbuf[sizeof "aaa.bbb.ccc.ddd"];
984263bc
MD
755#endif
756 if (isipv6) {
757 strcpy(dbuf, "[");
984263bc 758 strcat(dbuf, ip6_sprintf(&ip6->ip6_dst));
984263bc 759 strcat(dbuf, "]");
95b22adf
JH
760 strcpy(sbuf, "[");
761 strcat(sbuf, ip6_sprintf(&ip6->ip6_src));
984263bc
MD
762 strcat(sbuf, "]");
763 } else {
764 strcpy(dbuf, inet_ntoa(ip->ip_dst));
765 strcpy(sbuf, inet_ntoa(ip->ip_src));
766 }
767 switch (log_in_vain) {
768 case 1:
61896e3c 769 if (!(thflags & TH_SYN))
984263bc
MD
770 break;
771 case 2:
772 log(LOG_INFO,
773 "Connection attempt to TCP %s:%d "
774 "from %s:%d flags:0x%02x\n",
775 dbuf, ntohs(th->th_dport), sbuf,
776 ntohs(th->th_sport), thflags);
777 break;
778 default:
779 break;
780 }
781 }
d24ce1dc 782 if (blackhole) {
984263bc
MD
783 switch (blackhole) {
784 case 1:
785 if (thflags & TH_SYN)
786 goto drop;
787 break;
788 case 2:
789 goto drop;
790 default:
791 goto drop;
792 }
793 }
794 rstreason = BANDLIM_RST_CLOSEDPORT;
795 goto dropwithreset;
796 }
61896e3c
JH
797
798#ifdef IPSEC
799 if (isipv6) {
800 if (ipsec6_in_reject_so(m, inp->inp_socket)) {
801 ipsec6stat.in_polvio++;
802 goto drop;
803 }
804 } else {
805 if (ipsec4_in_reject_so(m, inp->inp_socket)) {
806 ipsecstat.in_polvio++;
807 goto drop;
808 }
809 }
810#endif
811#ifdef FAST_IPSEC
812 if (isipv6) {
813 if (ipsec6_in_reject(m, inp))
814 goto drop;
815 } else {
816 if (ipsec4_in_reject(m, inp))
817 goto drop;
818 }
819#endif
95926362
MD
820 /* Check the minimum TTL for socket. */
821#ifdef INET6
822 if ((isipv6 ? ip6->ip6_hlim : ip->ip_ttl) < inp->inp_ip_minttl)
823 goto drop;
824#endif
61896e3c 825
984263bc
MD
826 tp = intotcpcb(inp);
827 if (tp == NULL) {
828 rstreason = BANDLIM_RST_CLOSEDPORT;
829 goto dropwithreset;
830 }
eb594563 831 if (tp->t_state <= TCPS_CLOSED)
984263bc
MD
832 goto drop;
833
834 /* Unscale the window into a 32-bit value. */
95b22adf 835 if (!(thflags & TH_SYN))
984263bc
MD
836 tiwin = th->th_win << tp->snd_scale;
837 else
838 tiwin = th->th_win;
839
840 so = inp->inp_socket;
47654766 841
984263bc 842#ifdef TCPDEBUG
47654766
JH
843 if (so->so_options & SO_DEBUG) {
844 ostate = tp->t_state;
845 if (isipv6)
95b22adf 846 bcopy(ip6, tcp_saveipgen, sizeof(*ip6));
47654766 847 else
95b22adf 848 bcopy(ip, tcp_saveipgen, sizeof(*ip));
47654766
JH
849 tcp_savetcp = *th;
850 }
984263bc 851#endif
47654766 852
407e896e 853 bzero(&to, sizeof to);
d24ce1dc 854
47654766
JH
855 if (so->so_options & SO_ACCEPTCONN) {
856 struct in_conninfo inc;
857
984263bc 858#ifdef INET6
d24ce1dc 859 inc.inc_isipv6 = (isipv6 == TRUE);
984263bc
MD
860#endif
861 if (isipv6) {
862 inc.inc6_faddr = ip6->ip6_src;
863 inc.inc6_laddr = ip6->ip6_dst;
864 inc.inc6_route.ro_rt = NULL; /* XXX */
865 } else {
866 inc.inc_faddr = ip->ip_src;
867 inc.inc_laddr = ip->ip_dst;
868 inc.inc_route.ro_rt = NULL; /* XXX */
869 }
870 inc.inc_fport = th->th_sport;
871 inc.inc_lport = th->th_dport;
872
61896e3c
JH
873 /*
874 * If the state is LISTEN then ignore segment if it contains
984263bc
MD
875 * a RST. If the segment contains an ACK then it is bad and
876 * send a RST. If it does not contain a SYN then it is not
877 * interesting; drop it.
878 *
879 * If the state is SYN_RECEIVED (syncache) and seg contains
880 * an ACK, but not for our SYN/ACK, send a RST. If the seg
881 * contains a RST, check the sequence number to see if it
882 * is a valid reset segment.
883 */
61896e3c
JH
884 if ((thflags & (TH_RST | TH_ACK | TH_SYN)) != TH_SYN) {
885 if ((thflags & (TH_RST | TH_ACK | TH_SYN)) == TH_ACK) {
984263bc
MD
886 if (!syncache_expand(&inc, th, &so, m)) {
887 /*
888 * No syncache entry, or ACK was not
889 * for our SYN/ACK. Send a RST.
890 */
891 tcpstat.tcps_badsyn++;
892 rstreason = BANDLIM_RST_OPENPORT;
893 goto dropwithreset;
894 }
895 if (so == NULL)
896 /*
897 * Could not complete 3-way handshake,
898 * connection is being closed down, and
899 * syncache will free mbuf.
900 */
901 return;
902 /*
903 * Socket is created in state SYN_RECEIVED.
904 * Continue processing segment.
905 */
ed894f8c 906 inp = so->so_pcb;
984263bc
MD
907 tp = intotcpcb(inp);
908 /*
909 * This is what would have happened in
910 * tcp_output() when the SYN,ACK was sent.
911 */
912 tp->snd_up = tp->snd_una;
913 tp->snd_max = tp->snd_nxt = tp->iss + 1;
914 tp->last_ack_sent = tp->rcv_nxt;
915/*
916 * XXX possible bug - it doesn't appear that tp->snd_wnd is unscaled
917 * until the _second_ ACK is received:
918 * rcv SYN (set wscale opts) --> send SYN/ACK, set snd_wnd = window.
919 * rcv ACK, calculate tiwin --> process SYN_RECEIVED, determine wscale,
61896e3c 920 * move to ESTAB, set snd_wnd to tiwin.
d24ce1dc 921 */
984263bc
MD
922 tp->snd_wnd = tiwin; /* unscaled */
923 goto after_listen;
924 }
925 if (thflags & TH_RST) {
926 syncache_chkrst(&inc, th);
927 goto drop;
928 }
929 if (thflags & TH_ACK) {
930 syncache_badack(&inc);
931 tcpstat.tcps_badsyn++;
932 rstreason = BANDLIM_RST_OPENPORT;
933 goto dropwithreset;
934 }
935 goto drop;
936 }
937
938 /*
61896e3c 939 * Segment's flags are (SYN) or (SYN | FIN).
984263bc
MD
940 */
941#ifdef INET6
942 /*
943 * If deprecated address is forbidden,
944 * we do not accept SYN to deprecated interface
945 * address to prevent any new inbound connection from
946 * getting established.
947 * When we do not accept SYN, we send a TCP RST,
948 * with deprecated source address (instead of dropping
949 * it). We compromise it as it is much better for peer
950 * to send a RST, and RST will be the final packet
951 * for the exchange.
952 *
953 * If we do not forbid deprecated addresses, we accept
954 * the SYN packet. RFC2462 does not suggest dropping
955 * SYN in this case.
956 * If we decipher RFC2462 5.5.4, it says like this:
957 * 1. use of deprecated addr with existing
958 * communication is okay - "SHOULD continue to be
959 * used"
960 * 2. use of it with new communication:
961 * (2a) "SHOULD NOT be used if alternate address
61896e3c 962 * with sufficient scope is available"
984263bc
MD
963 * (2b) nothing mentioned otherwise.
964 * Here we fall into (2b) case as we have no choice in
965 * our source address selection - we must obey the peer.
966 *
967 * The wording in RFC2462 is confusing, and there are
968 * multiple description text for deprecated address
969 * handling - worse, they are not exactly the same.
970 * I believe 5.5.4 is the best one, so we follow 5.5.4.
971 */
972 if (isipv6 && !ip6_use_deprecated) {
973 struct in6_ifaddr *ia6;
974
975 if ((ia6 = ip6_getdstifaddr(m)) &&
976 (ia6->ia6_flags & IN6_IFF_DEPRECATED)) {
977 tp = NULL;
978 rstreason = BANDLIM_RST_OPENPORT;
979 goto dropwithreset;
980 }
981 }
982#endif
983 /*
984 * If it is from this socket, drop it, it must be forged.
985 * Don't bother responding if the destination was a broadcast.
986 */
987 if (th->th_dport == th->th_sport) {
988 if (isipv6) {
989 if (IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst,
990 &ip6->ip6_src))
991 goto drop;
992 } else {
993 if (ip->ip_dst.s_addr == ip->ip_src.s_addr)
994 goto drop;
995 }
996 }
997 /*
998 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN
999 *
1000 * Note that it is quite possible to receive unicast
1001 * link-layer packets with a broadcast IP address. Use
1002 * in_broadcast() to find them.
1003 */
61896e3c 1004 if (m->m_flags & (M_BCAST | M_MCAST))
984263bc
MD
1005 goto drop;
1006 if (isipv6) {
1007 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
1008 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src))
1009 goto drop;
1010 } else {
1011 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) ||
1012 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
1013 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) ||
1014 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif))
1015 goto drop;
1016 }
1017 /*
1018 * SYN appears to be valid; create compressed TCP state
1019 * for syncache, or perform t/tcp connection.
1020 */
1021 if (so->so_qlen <= so->so_qlimit) {
95b22adf 1022 tcp_dooptions(&to, optp, optlen, TRUE);
984263bc
MD
1023 if (!syncache_add(&inc, &to, th, &so, m))
1024 goto drop;
1025 if (so == NULL)
1026 /*
1027 * Entry added to syncache, mbuf used to
1028 * send SYN,ACK packet.
1029 */
1030 return;
ed894f8c 1031 inp = so->so_pcb;
984263bc
MD
1032 tp = intotcpcb(inp);
1033 tp->snd_wnd = tiwin;
1034 tp->t_starttime = ticks;
1035 tp->t_state = TCPS_ESTABLISHED;
1036
1037 /*
1038 * If there is a FIN, or if there is data and the
1039 * connection is local, then delay SYN,ACK(SYN) in
1040 * the hope of piggy-backing it on a response
1041 * segment. Otherwise must send ACK now in case
1042 * the other side is slow starting.
1043 */
1044 if (DELAY_ACK(tp) &&
1045 ((thflags & TH_FIN) ||
1046 (tlen != 0 &&
1047 ((isipv6 && in6_localaddr(&inp->in6p_faddr)) ||
1048 (!isipv6 && in_localaddr(inp->inp_faddr)))))) {
a48c5dd5
SZ
1049 tcp_callout_reset(tp, tp->tt_delack,
1050 tcp_delacktime, tcp_timer_delack);
984263bc 1051 tp->t_flags |= TF_NEEDSYN;
a48c5dd5 1052 } else {
984263bc 1053 tp->t_flags |= (TF_ACKNOW | TF_NEEDSYN);
a48c5dd5 1054 }
984263bc
MD
1055
1056 tcpstat.tcps_connects++;
1057 soisconnected(so);
1058 goto trimthenstep6;
1059 }
1060 goto drop;
1061 }
1062after_listen:
1063
984263bc 1064 /* should not happen - syncache should pick up these connections */
61896e3c 1065 KASSERT(tp->t_state != TCPS_LISTEN, ("tcp_input: TCPS_LISTEN state"));
984263bc 1066
5b0b9fa5
PA
1067 /*
1068 * This is the second part of the MSS DoS prevention code (after
1069 * minmss on the sending side) and it deals with too many too small
1070 * tcp packets in a too short timeframe (1 second).
1071 *
153d34ac
MD
1072 * XXX Removed. This code was crap. It does not scale to network
1073 * speed, and default values break NFS. Gone.
5b0b9fa5 1074 */
153d34ac 1075 /* REMOVED */
5b0b9fa5 1076
984263bc
MD
1077 /*
1078 * Segment received on connection.
efca2b8e
MD
1079 *
1080 * Reset idle time and keep-alive timer. Don't waste time if less
1081 * then a second has elapsed. Only update t_rcvtime for non-SYN
1082 * packets.
1083 *
1084 * Handle the case where one side thinks the connection is established
1085 * but the other side has, say, rebooted without cleaning out the
1086 * connection. The SYNs could be construed as an attack and wind
1087 * up ignored, but in case it isn't an attack we can validate the
1088 * connection by forcing a keepalive.
984263bc 1089 */
efca2b8e
MD
1090 if (TCPS_HAVEESTABLISHED(tp->t_state) && (ticks - tp->t_rcvtime) > hz) {
1091 if ((thflags & (TH_SYN | TH_ACK)) == TH_SYN) {
1092 tp->t_flags |= TF_KEEPALIVE;
1093 tcp_callout_reset(tp, tp->tt_keep, hz / 2,
1094 tcp_timer_keep);
1095 } else {
1096 tp->t_rcvtime = ticks;
1097 tp->t_flags &= ~TF_KEEPALIVE;
1098 tcp_callout_reset(tp, tp->tt_keep, tcp_keepidle,
1099 tcp_timer_keep);
1100 }
a48c5dd5 1101 }
984263bc
MD
1102
1103 /*
1104 * Process options.
1105 * XXX this is tradtitional behavior, may need to be cleaned up.
1106 */
95b22adf 1107 tcp_dooptions(&to, optp, optlen, (thflags & TH_SYN) != 0);
ad0af98b 1108 if (tp->t_state == TCPS_SYN_SENT && (thflags & TH_SYN)) {
984263bc
MD
1109 if (to.to_flags & TOF_SCALE) {
1110 tp->t_flags |= TF_RCVD_SCALE;
1111 tp->requested_s_scale = to.to_requested_s_scale;
1112 }
1113 if (to.to_flags & TOF_TS) {
1114 tp->t_flags |= TF_RCVD_TSTMP;
1115 tp->ts_recent = to.to_tsval;
1116 tp->ts_recent_age = ticks;
1117 }
984263bc
MD
1118 if (to.to_flags & TOF_MSS)
1119 tcp_mss(tp, to.to_mss);
91489f6b
JH
1120 /*
1121 * Only set the TF_SACK_PERMITTED per-connection flag
1122 * if we got a SACK_PERMITTED option from the other side
1123 * and the global tcp_do_sack variable is true.
1124 */
1125 if (tcp_do_sack && (to.to_flags & TOF_SACK_PERMITTED))
1126 tp->t_flags |= TF_SACK_PERMITTED;
984263bc
MD
1127 }
1128
1129 /*
1130 * Header prediction: check for the two common cases
1131 * of a uni-directional data xfer. If the packet has
1132 * no control flags, is in-sequence, the window didn't
1133 * change and we're not retransmitting, it's a
1134 * candidate. If the length is zero and the ack moved
1135 * forward, we're the sender side of the xfer. Just
1136 * free the data acked & wake any higher level process
1137 * that was blocked waiting for space. If the length
1138 * is non-zero and the ack didn't move, we're the
1139 * receiver side. If we're getting packets in-order
1140 * (the reassembly queue is empty), add the data to
1141 * the socket buffer and note that we need a delayed ack.
1142 * Make sure that the hidden state-flags are also off.
1143 * Since we check for TCPS_ESTABLISHED above, it can only
1144 * be TH_NEEDSYN.
1145 */
1146 if (tp->t_state == TCPS_ESTABLISHED &&
1147 (thflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK &&
61896e3c
JH
1148 !(tp->t_flags & (TF_NEEDSYN | TF_NEEDFIN)) &&
1149 (!(to.to_flags & TOF_TS) ||
984263bc 1150 TSTMP_GEQ(to.to_tsval, tp->ts_recent)) &&
984263bc 1151 th->th_seq == tp->rcv_nxt &&
984263bc
MD
1152 tp->snd_nxt == tp->snd_max) {
1153
1154 /*
1155 * If last ACK falls within this segment's sequence numbers,
1156 * record the timestamp.
1157 * NOTE that the test is modified according to the latest
1158 * proposal of the tcplw@cray.com list (Braden 1993/04/26).
1159 */
61896e3c 1160 if ((to.to_flags & TOF_TS) &&
984263bc
MD
1161 SEQ_LEQ(th->th_seq, tp->last_ack_sent)) {
1162 tp->ts_recent_age = ticks;
1163 tp->ts_recent = to.to_tsval;
1164 }
1165
1166 if (tlen == 0) {
1167 if (SEQ_GT(th->th_ack, tp->snd_una) &&
1168 SEQ_LEQ(th->th_ack, tp->snd_max) &&
1169 tp->snd_cwnd >= tp->snd_wnd &&
95b22adf 1170 !IN_FASTRECOVERY(tp)) {
984263bc 1171 /*
be23faf1 1172 * This is a pure ack for outstanding data.
984263bc
MD
1173 */
1174 ++tcpstat.tcps_predack;
1175 /*
1176 * "bad retransmit" recovery
bfdb979e
JH
1177 *
1178 * If Eifel detection applies, then
1179 * it is deterministic, so use it
1180 * unconditionally over the old heuristic.
1181 * Otherwise, fall back to the old heuristic.
984263bc 1182 */
bfdb979e
JH
1183 if (tcp_do_eifel_detect &&
1184 (to.to_flags & TOF_TS) && to.to_tsecr &&
1185 (tp->t_flags & TF_FIRSTACCACK)) {
1186 /* Eifel detection applicable. */
1187 if (to.to_tsecr < tp->t_rexmtTS) {
1188 tcp_revert_congestion_state(tp);
1189 ++tcpstat.tcps_eifeldetected;
1190 }
1191 } else if (tp->t_rxtshift == 1 &&
1192 ticks < tp->t_badrxtwin) {
1193 tcp_revert_congestion_state(tp);
1194 ++tcpstat.tcps_rttdetected;
984263bc 1195 }
8819433a
JH
1196 tp->t_flags &= ~(TF_FIRSTACCACK |
1197 TF_FASTREXMT | TF_EARLYREXMT);
984263bc
MD
1198 /*
1199 * Recalculate the retransmit timer / rtt.
1200 *
d24ce1dc 1201 * Some machines (certain windows boxes)
984263bc
MD
1202 * send broken timestamp replies during the
1203 * SYN+ACK phase, ignore timestamps of 0.
1204 */
95b22adf 1205 if ((to.to_flags & TOF_TS) && to.to_tsecr) {
984263bc 1206 tcp_xmit_timer(tp,
95b22adf 1207 ticks - to.to_tsecr + 1);
984263bc 1208 } else if (tp->t_rtttime &&
95b22adf 1209 SEQ_GT(th->th_ack, tp->t_rtseq)) {
984263bc
MD
1210 tcp_xmit_timer(tp,
1211 ticks - tp->t_rtttime);
1212 }
1213 tcp_xmit_bandwidth_limit(tp, th->th_ack);
1214 acked = th->th_ack - tp->snd_una;
1215 tcpstat.tcps_rcvackpack++;
1216 tcpstat.tcps_rcvackbyte += acked;
6d49aa6f 1217 sbdrop(&so->so_snd.sb, acked);
cfb3f3f4 1218 tp->snd_recover = th->th_ack - 1;
9845754e 1219 tp->snd_una = th->th_ack;
984263bc 1220 tp->t_dupacks = 0;
df9d7670
JH
1221 /*
1222 * Update window information.
1223 */
1224 if (tiwin != tp->snd_wnd &&
1225 acceptable_window_update(tp, th, tiwin)) {
1226 /* keep track of pure window updates */
1227 if (tp->snd_wl2 == th->th_ack &&
1228 tiwin > tp->snd_wnd)
1229 tcpstat.tcps_rcvwinupd++;
1230 tp->snd_wnd = tiwin;
1231 tp->snd_wl1 = th->th_seq;
1232 tp->snd_wl2 = th->th_ack;
1233 if (tp->snd_wnd > tp->max_sndwnd)
1234 tp->max_sndwnd = tp->snd_wnd;
1235 }
984263bc
MD
1236 m_freem(m);
1237 ND6_HINT(tp); /* some progress has been done */
984263bc
MD
1238 /*
1239 * If all outstanding data are acked, stop
1240 * retransmit timer, otherwise restart timer
1241 * using current (possibly backed-off) value.
1242 * If process is waiting for space,
1243 * wakeup/selwakeup/signal. If data
1244 * are ready to send, let tcp_output
1245 * decide between more output or persist.
1246 */
a48c5dd5
SZ
1247 if (tp->snd_una == tp->snd_max) {
1248 tcp_callout_stop(tp, tp->tt_rexmt);
1249 } else if (!tcp_callout_active(tp,
1250 tp->tt_persist)) {
1251 tcp_callout_reset(tp, tp->tt_rexmt,
1252 tp->t_rxtcur, tcp_timer_rexmt);
1253 }
984263bc 1254 sowwakeup(so);
6d49aa6f 1255 if (so->so_snd.ssb_cc > 0)
f23061d4 1256 tcp_output(tp);
984263bc
MD
1257 return;
1258 }
df9d7670
JH
1259 } else if (tiwin == tp->snd_wnd &&
1260 th->th_ack == tp->snd_una &&
984263bc 1261 LIST_EMPTY(&tp->t_segq) &&
6d49aa6f 1262 tlen <= ssb_space(&so->so_rcv)) {
46e92930 1263 u_long newsize = 0; /* automatic sockbuf scaling */
984263bc 1264 /*
be23faf1 1265 * This is a pure, in-sequence data packet
984263bc
MD
1266 * with nothing on the reassembly queue and
1267 * we have enough buffer space to take it.
1268 */
1269 ++tcpstat.tcps_preddat;
1270 tp->rcv_nxt += tlen;
1271 tcpstat.tcps_rcvpack++;
1272 tcpstat.tcps_rcvbyte += tlen;
1273 ND6_HINT(tp); /* some progress has been done */
5b0b9fa5
PA
1274 /*
1275 * Automatic sizing of receive socket buffer. Often the send
1276 * buffer size is not optimally adjusted to the actual network
1277 * conditions at hand (delay bandwidth product). Setting the
1278 * buffer size too small limits throughput on links with high
1279 * bandwidth and high delay (eg. trans-continental/oceanic links).
1280 *
1281 * On the receive side the socket buffer memory is only rarely
1282 * used to any significant extent. This allows us to be much
1283 * more aggressive in scaling the receive socket buffer. For
1284 * the case that the buffer space is actually used to a large
1285 * extent and we run out of kernel memory we can simply drop
1286 * the new segments; TCP on the sender will just retransmit it
1287 * later. Setting the buffer size too big may only consume too
1288 * much kernel memory if the application doesn't read() from
1289 * the socket or packet loss or reordering makes use of the
1290 * reassembly queue.
1291 *
1292 * The criteria to step up the receive buffer one notch are:
1293 * 1. the number of bytes received during the time it takes
1294 * one timestamp to be reflected back to us (the RTT);
1295 * 2. received bytes per RTT is within seven eighth of the
1296 * current socket buffer size;
1297 * 3. receive buffer size has not hit maximal automatic size;
1298 *
1299 * This algorithm does one step per RTT at most and only if
1300 * we receive a bulk stream w/o packet losses or reorderings.
1301 * Shrinking the buffer during idle times is not necessary as
1302 * it doesn't consume any memory when idle.
1303 *
1304 * TODO: Only step up if the application is actually serving
1305 * the buffer to better manage the socket buffer resources.
1306 */
1307 if (tcp_do_autorcvbuf &&
1308 to.to_tsecr &&
1309 (so->so_rcv.ssb_flags & SSB_AUTOSIZE)) {
1310 if (to.to_tsecr > tp->rfbuf_ts &&
1311 to.to_tsecr - tp->rfbuf_ts < hz) {
1312 if (tp->rfbuf_cnt >
1313 (so->so_rcv.ssb_hiwat / 8 * 7) &&
1314 so->so_rcv.ssb_hiwat <
1315 tcp_autorcvbuf_max) {
1316 newsize =
46e92930
MD
1317 ulmin(so->so_rcv.ssb_hiwat +
1318 tcp_autorcvbuf_inc,
1319 tcp_autorcvbuf_max);
5b0b9fa5
PA
1320 }
1321 /* Start over with next RTT. */
1322 tp->rfbuf_ts = 0;
1323 tp->rfbuf_cnt = 0;
1324 } else
1325 tp->rfbuf_cnt += tlen; /* add up */
1326 }
984263bc
MD
1327 /*
1328 * Add data to socket buffer.
1329 */
1330 if (so->so_state & SS_CANTRCVMORE) {
1331 m_freem(m);
1332 } else {
5b0b9fa5 1333 /*
46e92930
MD
1334 * Set new socket buffer size, give up when
1335 * limit is reached.
1336 *
1337 * Adjusting the size can mess up ACK
1338 * sequencing when pure window updates are
1339 * being avoided (which is the default),
1340 * so force an ack.
5b0b9fa5 1341 */
46e92930
MD
1342 if (newsize) {
1343 tp->t_flags |= TF_RXRESIZED;
5b0b9fa5 1344 if (!ssb_reserve(&so->so_rcv, newsize,
46e92930
MD
1345 so, NULL)) {
1346 so->so_rcv.ssb_flags &= ~SSB_AUTOSIZE;
1347 }
1348 if (newsize >=
1349 (TCP_MAXWIN << tp->rcv_scale)) {
5b0b9fa5 1350 so->so_rcv.ssb_flags &= ~SSB_AUTOSIZE;
46e92930
MD
1351 }
1352 }
09cf73e0 1353 m_adj(m, drop_hdrlen); /* delayed header drop */
6d49aa6f 1354 ssb_appendstream(&so->so_rcv, m);
984263bc
MD
1355 }
1356 sorwakeup(so);
2b1ce38a
MD
1357 /*
1358 * This code is responsible for most of the ACKs
1359 * the TCP stack sends back after receiving a data
1360 * packet. Note that the DELAY_ACK check fails if
1361 * the delack timer is already running, which results
1362 * in an ack being sent every other packet (which is
1363 * what we want).
72b37eeb
MD
1364 *
1365 * We then further aggregate acks by not actually
1366 * sending one until the protocol thread has completed
1367 * processing the current backlog of packets. This
1368 * does not delay the ack any further, but allows us
1369 * to take advantage of the packet aggregation that
1370 * high speed NICs do (usually blocks of 8-10 packets)
1371 * to send a single ack rather then four or five acks,
1372 * greatly reducing the ack rate, the return channel
1373 * bandwidth, and the protocol overhead on both ends.
1374 *
1375 * Since this also has the effect of slowing down
1376 * the exponential slow-start ramp-up, systems with
1377 * very large bandwidth-delay products might want
1378 * to turn the feature off.
2b1ce38a 1379 */
984263bc 1380 if (DELAY_ACK(tp)) {
a48c5dd5
SZ
1381 tcp_callout_reset(tp, tp->tt_delack,
1382 tcp_delacktime, tcp_timer_delack);
72b37eeb 1383 } else if (tcp_aggregate_acks) {
984263bc 1384 tp->t_flags |= TF_ACKNOW;
61896e3c 1385 if (!(tp->t_flags & TF_ONOUTPUTQ)) {
2b1ce38a
MD
1386 tp->t_flags |= TF_ONOUTPUTQ;
1387 tp->tt_cpu = mycpu->gd_cpuid;
1388 TAILQ_INSERT_TAIL(
1389 &tcpcbackq[tp->tt_cpu],
1390 tp, t_outputq);
1391 }
72b37eeb
MD
1392 } else {
1393 tp->t_flags |= TF_ACKNOW;
1394 tcp_output(tp);
984263bc
MD
1395 }
1396 return;
1397 }
1398 }
1399
1400 /*
1401 * Calculate amount of space in receive window,
1402 * and then do TCP input processing.
1403 * Receive window is amount of space in rcv queue,
1404 * but not less than advertised window.
1405 */
6d49aa6f 1406 recvwin = ssb_space(&so->so_rcv);
61896e3c
JH
1407 if (recvwin < 0)
1408 recvwin = 0;
1409 tp->rcv_wnd = imax(recvwin, (int)(tp->rcv_adv - tp->rcv_nxt));
984263bc 1410
5b0b9fa5
PA
1411 /* Reset receive buffer auto scaling when not in bulk receive mode. */
1412 tp->rfbuf_ts = 0;
1413 tp->rfbuf_cnt = 0;
1414
984263bc 1415 switch (tp->t_state) {
984263bc
MD
1416 /*
1417 * If the state is SYN_RECEIVED:
1418 * if seg contains an ACK, but not for our SYN/ACK, send a RST.
1419 */
1420 case TCPS_SYN_RECEIVED:
1421 if ((thflags & TH_ACK) &&
1422 (SEQ_LEQ(th->th_ack, tp->snd_una) ||
1423 SEQ_GT(th->th_ack, tp->snd_max))) {
1424 rstreason = BANDLIM_RST_OPENPORT;
1425 goto dropwithreset;
1426 }
1427 break;
1428
1429 /*
1430 * If the state is SYN_SENT:
1431 * if seg contains an ACK, but not for our SYN, drop the input.
1432 * if seg contains a RST, then drop the connection.
1433 * if seg does not contain SYN, then drop it.
1434 * Otherwise this is an acceptable SYN segment
1435 * initialize tp->rcv_nxt and tp->irs
1436 * if seg contains ack then advance tp->snd_una
1437 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state
1438 * arrange for segment to be acked (eventually)
1439 * continue processing rest of data/controls, beginning with URG
1440 */
1441 case TCPS_SYN_SENT:
984263bc
MD
1442 if ((thflags & TH_ACK) &&
1443 (SEQ_LEQ(th->th_ack, tp->iss) ||
1444 SEQ_GT(th->th_ack, tp->snd_max))) {
27b8aee3
AE
1445 rstreason = BANDLIM_UNLIMITED;
1446 goto dropwithreset;
984263bc
MD
1447 }
1448 if (thflags & TH_RST) {
1449 if (thflags & TH_ACK)
1450 tp = tcp_drop(tp, ECONNREFUSED);
1451 goto drop;
1452 }
61896e3c 1453 if (!(thflags & TH_SYN))
984263bc
MD
1454 goto drop;
1455 tp->snd_wnd = th->th_win; /* initial send window */
984263bc
MD
1456
1457 tp->irs = th->th_seq;
1458 tcp_rcvseqinit(tp);
1459 if (thflags & TH_ACK) {
27b8aee3 1460 /* Our SYN was acked. */
984263bc
MD
1461 tcpstat.tcps_connects++;
1462 soisconnected(so);
1463 /* Do window scaling on this connection? */
61896e3c 1464 if ((tp->t_flags & (TF_RCVD_SCALE | TF_REQ_SCALE)) ==
b5572302 1465 (TF_RCVD_SCALE | TF_REQ_SCALE)) {
984263bc
MD
1466 tp->snd_scale = tp->requested_s_scale;
1467 tp->rcv_scale = tp->request_r_scale;
1468 }
984263bc
MD
1469 tp->rcv_adv += tp->rcv_wnd;
1470 tp->snd_una++; /* SYN is acked */
a48c5dd5 1471 tcp_callout_stop(tp, tp->tt_rexmt);
984263bc
MD
1472 /*
1473 * If there's data, delay ACK; if there's also a FIN
1474 * ACKNOW will be turned on later.
1475 */
a48c5dd5
SZ
1476 if (DELAY_ACK(tp) && tlen != 0) {
1477 tcp_callout_reset(tp, tp->tt_delack,
1478 tcp_delacktime, tcp_timer_delack);
1479 } else {
984263bc 1480 tp->t_flags |= TF_ACKNOW;
a48c5dd5 1481 }
984263bc
MD
1482 /*
1483 * Received <SYN,ACK> in SYN_SENT[*] state.
1484 * Transitions:
1485 * SYN_SENT --> ESTABLISHED
1486 * SYN_SENT* --> FIN_WAIT_1
1487 */
1488 tp->t_starttime = ticks;
1489 if (tp->t_flags & TF_NEEDFIN) {
1490 tp->t_state = TCPS_FIN_WAIT_1;
1491 tp->t_flags &= ~TF_NEEDFIN;
1492 thflags &= ~TH_SYN;
1493 } else {
1494 tp->t_state = TCPS_ESTABLISHED;
a48c5dd5
SZ
1495 tcp_callout_reset(tp, tp->tt_keep, tcp_keepidle,
1496 tcp_timer_keep);
984263bc
MD
1497 }
1498 } else {
1499 /*
95b22adf 1500 * Received initial SYN in SYN-SENT[*] state =>
27b8aee3
AE
1501 * simultaneous open.
1502 * Do 3-way handshake:
61896e3c
JH
1503 * SYN-SENT -> SYN-RECEIVED
1504 * SYN-SENT* -> SYN-RECEIVED*
95b22adf 1505 */
984263bc 1506 tp->t_flags |= TF_ACKNOW;
a48c5dd5 1507 tcp_callout_stop(tp, tp->tt_rexmt);
27b8aee3 1508 tp->t_state = TCPS_SYN_RECEIVED;
984263bc
MD
1509 }
1510
1511trimthenstep6:
1512 /*
1513 * Advance th->th_seq to correspond to first data byte.
1514 * If data, trim to stay within window,
1515 * dropping FIN if necessary.
1516 */
1517 th->th_seq++;
1518 if (tlen > tp->rcv_wnd) {
1519 todrop = tlen - tp->rcv_wnd;
1520 m_adj(m, -todrop);
1521 tlen = tp->rcv_wnd;
1522 thflags &= ~TH_FIN;
1523 tcpstat.tcps_rcvpackafterwin++;
1524 tcpstat.tcps_rcvbyteafterwin += todrop;
1525 }
1526 tp->snd_wl1 = th->th_seq - 1;
1527 tp->rcv_up = th->th_seq;
1528 /*
1529 * Client side of transaction: already sent SYN and data.
1530 * If the remote host used T/TCP to validate the SYN,
1531 * our data will be ACK'd; if so, enter normal data segment
1532 * processing in the middle of step 5, ack processing.
1533 * Otherwise, goto step 6.
1534 */
95b22adf 1535 if (thflags & TH_ACK)
984263bc
MD
1536 goto process_ACK;
1537
1538 goto step6;
1539
1540 /*
1541 * If the state is LAST_ACK or CLOSING or TIME_WAIT:
27b8aee3 1542 * do normal processing (we no longer bother with T/TCP).
984263bc
MD
1543 */
1544 case TCPS_LAST_ACK:
1545 case TCPS_CLOSING:
1546 case TCPS_TIME_WAIT:
95b22adf 1547 break; /* continue normal processing */
984263bc
MD
1548 }
1549
1550 /*
1551 * States other than LISTEN or SYN_SENT.
1552 * First check the RST flag and sequence number since reset segments
1553 * are exempt from the timestamp and connection count tests. This
1554 * fixes a bug introduced by the Stevens, vol. 2, p. 960 bugfix
1555 * below which allowed reset segments in half the sequence space
1556 * to fall though and be processed (which gives forged reset
1557 * segments with a random sequence number a 50 percent chance of
1558 * killing a connection).
1559 * Then check timestamp, if present.
1560 * Then check the connection count, if present.
1561 * Then check that at least some bytes of segment are within
1562 * receive window. If segment begins before rcv_nxt,
1563 * drop leading data (and SYN); if nothing left, just ack.
1564 *
1565 *
1566 * If the RST bit is set, check the sequence number to see
1567 * if this is a valid reset segment.
1568 * RFC 793 page 37:
1569 * In all states except SYN-SENT, all reset (RST) segments
1570 * are validated by checking their SEQ-fields. A reset is
1571 * valid if its sequence number is in the window.
1572 * Note: this does not take into account delayed ACKs, so
1573 * we should test against last_ack_sent instead of rcv_nxt.
1574 * The sequence number in the reset segment is normally an
91489f6b 1575 * echo of our outgoing acknowledgement numbers, but some hosts
984263bc
MD
1576 * send a reset with the sequence number at the rightmost edge
1577 * of our receive window, and we have to handle this case.
1578 * If we have multiple segments in flight, the intial reset
1579 * segment sequence numbers will be to the left of last_ack_sent,
1580 * but they will eventually catch up.
1581 * In any case, it never made sense to trim reset segments to
1582 * fit the receive window since RFC 1122 says:
1583 * 4.2.2.12 RST Segment: RFC-793 Section 3.4
1584 *
1585 * A TCP SHOULD allow a received RST segment to include data.
1586 *
1587 * DISCUSSION
61896e3c
JH
1588 * It has been suggested that a RST segment could contain
1589 * ASCII text that encoded and explained the cause of the
91489f6b 1590 * RST. No standard has yet been established for such
61896e3c 1591 * data.
984263bc
MD
1592 *
1593 * If the reset segment passes the sequence number test examine
1594 * the state:
1595 * SYN_RECEIVED STATE:
1596 * If passive open, return to LISTEN state.
1597 * If active open, inform user that connection was refused.
1598 * ESTABLISHED, FIN_WAIT_1, FIN_WAIT_2, CLOSE_WAIT STATES:
1599 * Inform user that connection was reset, and close tcb.
1600 * CLOSING, LAST_ACK STATES:
1601 * Close the tcb.
1602 * TIME_WAIT STATE:
1603 * Drop the segment - see Stevens, vol. 2, p. 964 and
61896e3c 1604 * RFC 1337.
984263bc
MD
1605 */
1606 if (thflags & TH_RST) {
1607 if (SEQ_GEQ(th->th_seq, tp->last_ack_sent) &&
d4dbb5be 1608 SEQ_LEQ(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) {
984263bc
MD
1609 switch (tp->t_state) {
1610
1611 case TCPS_SYN_RECEIVED:
1612 so->so_error = ECONNREFUSED;
1613 goto close;
1614
1615 case TCPS_ESTABLISHED:
1616 case TCPS_FIN_WAIT_1:
1617 case TCPS_FIN_WAIT_2:
1618 case TCPS_CLOSE_WAIT:
1619 so->so_error = ECONNRESET;
1620 close:
1621 tp->t_state = TCPS_CLOSED;
1622 tcpstat.tcps_drops++;
1623 tp = tcp_close(tp);
1624 break;
1625
1626 case TCPS_CLOSING:
1627 case TCPS_LAST_ACK:
1628 tp = tcp_close(tp);
1629 break;
1630
1631 case TCPS_TIME_WAIT:
1632 break;
1633 }
1634 }
1635 goto drop;
1636 }
1637
1638 /*
1639 * RFC 1323 PAWS: If we have a timestamp reply on this segment
1640 * and it's less than ts_recent, drop it.
1641 */
61896e3c 1642 if ((to.to_flags & TOF_TS) && tp->ts_recent != 0 &&
984263bc
MD
1643 TSTMP_LT(to.to_tsval, tp->ts_recent)) {
1644
1645 /* Check to see if ts_recent is over 24 days old. */
1646 if ((int)(ticks - tp->ts_recent_age) > TCP_PAWS_IDLE) {
1647 /*
1648 * Invalidate ts_recent. If this segment updates
1649 * ts_recent, the age will be reset later and ts_recent
1650 * will get a valid value. If it does not, setting
1651 * ts_recent to zero will at least satisfy the
1652 * requirement that zero be placed in the timestamp
1653 * echo reply when ts_recent isn't valid. The
1654 * age isn't reset until we get a valid ts_recent
1655 * because we don't want out-of-order segments to be
1656 * dropped when ts_recent is old.
1657 */
1658 tp->ts_recent = 0;
1659 } else {
1660 tcpstat.tcps_rcvduppack++;
1661 tcpstat.tcps_rcvdupbyte += tlen;
1662 tcpstat.tcps_pawsdrop++;
1663 if (tlen)
1664 goto dropafterack;
1665 goto drop;
1666 }
1667 }
1668
984263bc
MD
1669 /*
1670 * In the SYN-RECEIVED state, validate that the packet belongs to
1671 * this connection before trimming the data to fit the receive
1672 * window. Check the sequence number versus IRS since we know
1673 * the sequence numbers haven't wrapped. This is a partial fix
1674 * for the "LAND" DoS attack.
1675 */
1676 if (tp->t_state == TCPS_SYN_RECEIVED && SEQ_LT(th->th_seq, tp->irs)) {
1677 rstreason = BANDLIM_RST_OPENPORT;
1678 goto dropwithreset;
1679 }
1680
1681 todrop = tp->rcv_nxt - th->th_seq;
1682 if (todrop > 0) {
91489f6b
JH
1683 if (TCP_DO_SACK(tp)) {
1684 /* Report duplicate segment at head of packet. */
1685 tp->reportblk.rblk_start = th->th_seq;
1686 tp->reportblk.rblk_end = th->th_seq + tlen;
1687 if (thflags & TH_FIN)
1688 ++tp->reportblk.rblk_end;
1689 if (SEQ_GT(tp->reportblk.rblk_end, tp->rcv_nxt))
1690 tp->reportblk.rblk_end = tp->rcv_nxt;
1691 tp->t_flags |= (TF_DUPSEG | TF_SACKLEFT | TF_ACKNOW);
1692 }
984263bc
MD
1693 if (thflags & TH_SYN) {
1694 thflags &= ~TH_SYN;
1695 th->th_seq++;
1696 if (th->th_urp > 1)
1697 th->th_urp--;
1698 else
1699 thflags &= ~TH_URG;
1700 todrop--;
1701 }
1702 /*
1703 * Following if statement from Stevens, vol. 2, p. 960.
1704 */
61896e3c
JH
1705 if (todrop > tlen ||
1706 (todrop == tlen && !(thflags & TH_FIN))) {
984263bc
MD
1707 /*
1708 * Any valid FIN must be to the left of the window.
1709 * At this point the FIN must be a duplicate or out
1710 * of sequence; drop it.
1711 */
1712 thflags &= ~TH_FIN;
1713
1714 /*
1715 * Send an ACK to resynchronize and drop any data.
1716 * But keep on processing for RST or ACK.
1717 */
1718 tp->t_flags |= TF_ACKNOW;
1719 todrop = tlen;
1720 tcpstat.tcps_rcvduppack++;
1721 tcpstat.tcps_rcvdupbyte += todrop;
1722 } else {
1723 tcpstat.tcps_rcvpartduppack++;
1724 tcpstat.tcps_rcvpartdupbyte += todrop;
1725 }
1726 drop_hdrlen += todrop; /* drop from the top afterwards */
1727 th->th_seq += todrop;
1728 tlen -= todrop;
1729 if (th->th_urp > todrop)
1730 th->th_urp -= todrop;
1731 else {
1732 thflags &= ~TH_URG;
1733 th->th_urp = 0;
1734 }
1735 }
1736
1737 /*
1738 * If new data are received on a connection after the
1739 * user processes are gone, then RST the other end.
1740 */
1741 if ((so->so_state & SS_NOFDREF) &&
1742 tp->t_state > TCPS_CLOSE_WAIT && tlen) {
1743 tp = tcp_close(tp);
1744 tcpstat.tcps_rcvafterclose++;
1745 rstreason = BANDLIM_UNLIMITED;
1746 goto dropwithreset;
1747 }
1748
1749 /*
1750 * If segment ends after window, drop trailing data
1751 * (and PUSH and FIN); if nothing left, just ACK.
1752 */
61896e3c 1753 todrop = (th->th_seq + tlen) - (tp->rcv_nxt + tp->rcv_wnd);
984263bc
MD
1754 if (todrop > 0) {
1755 tcpstat.tcps_rcvpackafterwin++;
1756 if (todrop >= tlen) {
1757 tcpstat.tcps_rcvbyteafterwin += tlen;
1758 /*
1759 * If a new connection request is received
1760 * while in TIME_WAIT, drop the old connection
1761 * and start over if the sequence numbers
1762 * are above the previous ones.
1763 */
1764 if (thflags & TH_SYN &&
1765 tp->t_state == TCPS_TIME_WAIT &&
1766 SEQ_GT(th->th_seq, tp->rcv_nxt)) {
1767 tp = tcp_close(tp);
1768 goto findpcb;
1769 }
1770 /*
1771 * If window is closed can only take segments at
1772 * window edge, and have to drop data and PUSH from
1773 * incoming segments. Continue processing, but
1774 * remember to ack. Otherwise, drop segment
1775 * and ack.
1776 */
1777 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) {
1778 tp->t_flags |= TF_ACKNOW;
1779 tcpstat.tcps_rcvwinprobe++;
1780 } else
1781 goto dropafterack;
1782 } else
1783 tcpstat.tcps_rcvbyteafterwin += todrop;
1784 m_adj(m, -todrop);
1785 tlen -= todrop;
61896e3c 1786 thflags &= ~(TH_PUSH | TH_FIN);
984263bc
MD
1787 }
1788
1789 /*
1790 * If last ACK falls within this segment's sequence numbers,
1791 * record its timestamp.
ad0af98b
ND
1792 * NOTE:
1793 * 1) That the test incorporates suggestions from the latest
1794 * proposal of the tcplw@cray.com list (Braden 1993/04/26).
1795 * 2) That updating only on newer timestamps interferes with
1796 * our earlier PAWS tests, so this check should be solely
1797 * predicated on the sequence space of this segment.
1798 * 3) That we modify the segment boundary check to be
1799 * Last.ACK.Sent <= SEG.SEQ + SEG.LEN
1800 * instead of RFC1323's
1801 * Last.ACK.Sent < SEG.SEQ + SEG.LEN,
1802 * This modified check allows us to overcome RFC1323's
1803 * limitations as described in Stevens TCP/IP Illustrated
1804 * Vol. 2 p.869. In such cases, we can still calculate the
1805 * RTT correctly when RCV.NXT == Last.ACK.Sent.
984263bc 1806 */
ad0af98b
ND
1807 if ((to.to_flags & TOF_TS) && SEQ_LEQ(th->th_seq, tp->last_ack_sent) &&
1808 SEQ_LEQ(tp->last_ack_sent, (th->th_seq + tlen
1809 + ((thflags & TH_SYN) != 0)
1810 + ((thflags & TH_FIN) != 0)))) {
984263bc
MD
1811 tp->ts_recent_age = ticks;
1812 tp->ts_recent = to.to_tsval;
1813 }
1814
1815 /*
1816 * If a SYN is in the window, then this is an
1817 * error and we send an RST and drop the connection.
1818 */
1819 if (thflags & TH_SYN) {
1820 tp = tcp_drop(tp, ECONNRESET);
1821 rstreason = BANDLIM_UNLIMITED;
1822 goto dropwithreset;
1823 }
1824
1825 /*
1826 * If the ACK bit is off: if in SYN-RECEIVED state or SENDSYN
1827 * flag is on (half-synchronized state), then queue data for
1828 * later processing; else drop segment and return.
1829 */
61896e3c 1830 if (!(thflags & TH_ACK)) {
984263bc
MD
1831 if (tp->t_state == TCPS_SYN_RECEIVED ||
1832 (tp->t_flags & TF_NEEDSYN))
1833 goto step6;
1834 else
1835 goto drop;
1836 }
1837
1838 /*
1839 * Ack processing.
1840 */
1841 switch (tp->t_state) {
984263bc 1842 /*
91489f6b 1843 * In SYN_RECEIVED state, the ACK acknowledges our SYN, so enter
984263bc
MD
1844 * ESTABLISHED state and continue processing.
1845 * The ACK was checked above.
1846 */
1847 case TCPS_SYN_RECEIVED:
1848
1849 tcpstat.tcps_connects++;
1850 soisconnected(so);
1851 /* Do window scaling? */
61896e3c 1852 if ((tp->t_flags & (TF_RCVD_SCALE | TF_REQ_SCALE)) ==
b5572302 1853 (TF_RCVD_SCALE | TF_REQ_SCALE)) {
984263bc
MD
1854 tp->snd_scale = tp->requested_s_scale;
1855 tp->rcv_scale = tp->request_r_scale;
1856 }
984263bc
MD
1857 /*
1858 * Make transitions:
1859 * SYN-RECEIVED -> ESTABLISHED
1860 * SYN-RECEIVED* -> FIN-WAIT-1
1861 */
1862 tp->t_starttime = ticks;
1863 if (tp->t_flags & TF_NEEDFIN) {
1864 tp->t_state = TCPS_FIN_WAIT_1;
1865 tp->t_flags &= ~TF_NEEDFIN;
1866 } else {
1867 tp->t_state = TCPS_ESTABLISHED;
a48c5dd5
SZ
1868 tcp_callout_reset(tp, tp->tt_keep, tcp_keepidle,
1869 tcp_timer_keep);
984263bc
MD
1870 }
1871 /*
1872 * If segment contains data or ACK, will call tcp_reass()
1873 * later; if not, do so now to pass queued data to user.
1874 */
61896e3c 1875 if (tlen == 0 && !(thflags & TH_FIN))
f23061d4 1876 tcp_reass(tp, NULL, NULL, NULL);
984263bc
MD
1877 /* fall into ... */
1878
1879 /*
1880 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range
1881 * ACKs. If the ack is in the range
1882 * tp->snd_una < th->th_ack <= tp->snd_max
1883 * then advance tp->snd_una to th->th_ack and drop
1884 * data from the retransmission queue. If this ACK reflects
1885 * more up to date window information we update our window information.
1886 */
1887 case TCPS_ESTABLISHED:
1888 case TCPS_FIN_WAIT_1:
1889 case TCPS_FIN_WAIT_2:
1890 case TCPS_CLOSE_WAIT:
1891 case TCPS_CLOSING:
1892 case TCPS_LAST_ACK:
1893 case TCPS_TIME_WAIT:
1894
1895 if (SEQ_LEQ(th->th_ack, tp->snd_una)) {
91489f6b
JH
1896 if (TCP_DO_SACK(tp))
1897 tcp_sack_update_scoreboard(tp, &to);
95b22adf
JH
1898 if (tlen != 0 || tiwin != tp->snd_wnd) {
1899 tp->t_dupacks = 0;
1900 break;
1901 }
1902 tcpstat.tcps_rcvdupack++;
a48c5dd5 1903 if (!tcp_callout_active(tp, tp->tt_rexmt) ||
91489f6b
JH
1904 th->th_ack != tp->snd_una) {
1905 tp->t_dupacks = 0;
1906 break;
1907 }
95b22adf 1908 /*
91489f6b 1909 * We have outstanding data (other than
95b22adf
JH
1910 * a window probe), this is a completely
1911 * duplicate ack (ie, window info didn't
1912 * change), the ack is the biggest we've
1913 * seen and we've seen exactly our rexmt
91489f6b 1914 * threshhold of them, so assume a packet
95b22adf
JH
1915 * has been dropped and retransmit it.
1916 * Kludge snd_nxt & the congestion
1917 * window so we send only this one
1918 * packet.
95b22adf 1919 */
91489f6b
JH
1920 if (IN_FASTRECOVERY(tp)) {
1921 if (TCP_DO_SACK(tp)) {
1922 /* No artifical cwnd inflation. */
1923 tcp_sack_rexmt(tp, th);
1924 } else {
1925 /*
1926 * Dup acks mean that packets
1927 * have left the network
1928 * (they're now cached at the
1929 * receiver) so bump cwnd by
1930 * the amount in the receiver
1931 * to keep a constant cwnd
1932 * packets in the network.
1933 */
1934 tp->snd_cwnd += tp->t_maxseg;
f23061d4 1935 tcp_output(tp);
91489f6b
JH
1936 }
1937 } else if (SEQ_LT(th->th_ack, tp->snd_recover)) {
95b22adf
JH
1938 tp->t_dupacks = 0;
1939 break;
95b22adf 1940 } else if (++tp->t_dupacks == tcprexmtthresh) {
91489f6b 1941 tcp_seq old_snd_nxt;
95b22adf
JH
1942 u_int win;
1943
8819433a 1944fastretransmit:
95b22adf
JH
1945 if (tcp_do_eifel_detect &&
1946 (tp->t_flags & TF_RCVD_TSTMP)) {
1947 tcp_save_congestion_state(tp);
1948 tp->t_flags |= TF_FASTREXMT;
1949 }
91489f6b
JH
1950 /*
1951 * We know we're losing at the current
1952 * window size, so do congestion avoidance:
1953 * set ssthresh to half the current window
1954 * and pull our congestion window back to the
1955 * new ssthresh.
1956 */
95b22adf
JH
1957 win = min(tp->snd_wnd, tp->snd_cwnd) / 2 /
1958 tp->t_maxseg;
1959 if (win < 2)
1960 win = 2;
1961 tp->snd_ssthresh = win * tp->t_maxseg;
1962 ENTER_FASTRECOVERY(tp);
1963 tp->snd_recover = tp->snd_max;
a48c5dd5 1964 tcp_callout_stop(tp, tp->tt_rexmt);
95b22adf 1965 tp->t_rtttime = 0;
91489f6b 1966 old_snd_nxt = tp->snd_nxt;
95b22adf
JH
1967 tp->snd_nxt = th->th_ack;
1968 tp->snd_cwnd = tp->t_maxseg;
f23061d4 1969 tcp_output(tp);
95b22adf 1970 ++tcpstat.tcps_sndfastrexmit;
91489f6b
JH
1971 tp->snd_cwnd = tp->snd_ssthresh;
1972 tp->rexmt_high = tp->snd_nxt;
1973 if (SEQ_GT(old_snd_nxt, tp->snd_nxt))
1974 tp->snd_nxt = old_snd_nxt;
95b22adf
JH
1975 KASSERT(tp->snd_limited <= 2,
1976 ("tp->snd_limited too big"));
91489f6b
JH
1977 if (TCP_DO_SACK(tp))
1978 tcp_sack_rexmt(tp, th);
1979 else
1980 tp->snd_cwnd += tp->t_maxseg *
1981 (tp->t_dupacks - tp->snd_limited);
95b22adf
JH
1982 } else if (tcp_do_limitedtransmit) {
1983 u_long oldcwnd = tp->snd_cwnd;
1984 tcp_seq oldsndmax = tp->snd_max;
9e707f76 1985 tcp_seq oldsndnxt = tp->snd_nxt;
95b22adf
JH
1986 /* outstanding data */
1987 uint32_t ownd = tp->snd_max - tp->snd_una;
1988 u_int sent;
ca94b4a6 1989
8819433a
JH
1990#define iceildiv(n, d) (((n)+(d)-1) / (d))
1991
95b22adf
JH
1992 KASSERT(tp->t_dupacks == 1 ||
1993 tp->t_dupacks == 2,
1994 ("dupacks not 1 or 2"));
1995 if (tp->t_dupacks == 1)
1996 tp->snd_limited = 0;
9e707f76 1997 tp->snd_nxt = tp->snd_max;
95b22adf
JH
1998 tp->snd_cwnd = ownd +
1999 (tp->t_dupacks - tp->snd_limited) *
2000 tp->t_maxseg;
f23061d4 2001 tcp_output(tp);
98cb2337
MD
2002
2003 /*
2004 * Other acks may have been processed,
2005 * snd_nxt cannot be reset to a value less
2006 * then snd_una.
2007 */
2008 if (SEQ_LT(oldsndnxt, oldsndmax)) {
2009 if (SEQ_GT(oldsndnxt, tp->snd_una))
6d08465d 2010 tp->snd_nxt = oldsndnxt;
98cb2337
MD
2011 else
2012 tp->snd_nxt = tp->snd_una;
2013 }
95b22adf
JH
2014 tp->snd_cwnd = oldcwnd;
2015 sent = tp->snd_max - oldsndmax;
2016 if (sent > tp->t_maxseg) {
2017 KASSERT((tp->t_dupacks == 2 &&
2018 tp->snd_limited == 0) ||
2019 (sent == tp->t_maxseg + 1 &&
2020 tp->t_flags & TF_SENTFIN),
2021 ("sent too much"));
2022 KASSERT(sent <= tp->t_maxseg * 2,
2023 ("sent too many segments"));
2024 tp->snd_limited = 2;
2025 tcpstat.tcps_sndlimited += 2;
2026 } else if (sent > 0) {
2027 ++tp->snd_limited;
2028 ++tcpstat.tcps_sndlimited;
2029 } else if (tcp_do_early_retransmit &&
2030 (tcp_do_eifel_detect &&
2031 (tp->t_flags & TF_RCVD_TSTMP)) &&
91489f6b 2032 ownd < 4 * tp->t_maxseg &&
95b22adf 2033 tp->t_dupacks + 1 >=
91489f6b
JH
2034 iceildiv(ownd, tp->t_maxseg) &&
2035 (!TCP_DO_SACK(tp) ||
f23061d4 2036 ownd <= tp->t_maxseg ||
91489f6b 2037 tcp_sack_has_sacked(&tp->scb,
f23061d4 2038 ownd - tp->t_maxseg))) {
95b22adf
JH
2039 ++tcpstat.tcps_sndearlyrexmit;
2040 tp->t_flags |= TF_EARLYREXMT;
2041 goto fastretransmit;
984263bc 2042 }
95b22adf
JH
2043 }
2044 goto drop;
984263bc
MD
2045 }
2046
2047 KASSERT(SEQ_GT(th->th_ack, tp->snd_una), ("th_ack <= snd_una"));
984263bc
MD
2048 tp->t_dupacks = 0;
2049 if (SEQ_GT(th->th_ack, tp->snd_max)) {
5a274421
JH
2050 /*
2051 * Detected optimistic ACK attack.
2052 * Force slow-start to de-synchronize attack.
2053 */
2054 tp->snd_cwnd = tp->t_maxseg;
8acdb67c 2055 tp->snd_wacked = 0;
5a274421 2056
984263bc
MD
2057 tcpstat.tcps_rcvacktoomuch++;
2058 goto dropafterack;
2059 }
2060 /*
2061 * If we reach this point, ACK is not a duplicate,
2062 * i.e., it ACKs something we sent.
2063 */
2064 if (tp->t_flags & TF_NEEDSYN) {
2065 /*
2066 * T/TCP: Connection was half-synchronized, and our
2067 * SYN has been ACK'd (so connection is now fully
2068 * synchronized). Go to non-starred state,
2069 * increment snd_una for ACK of SYN, and check if
2070 * we can do window scaling.
2071 */
2072 tp->t_flags &= ~TF_NEEDSYN;
2073 tp->snd_una++;
2074 /* Do window scaling? */
61896e3c
JH
2075 if ((tp->t_flags & (TF_RCVD_SCALE | TF_REQ_SCALE)) ==
2076 (TF_RCVD_SCALE | TF_REQ_SCALE)) {
984263bc
MD
2077 tp->snd_scale = tp->requested_s_scale;
2078 tp->rcv_scale = tp->request_r_scale;
2079 }
2080 }
2081
2082process_ACK:
2083 acked = th->th_ack - tp->snd_una;
2084 tcpstat.tcps_rcvackpack++;
2085 tcpstat.tcps_rcvackbyte += acked;
2086
b5572302 2087 if (tcp_do_eifel_detect && acked > 0 &&
95b22adf 2088 (to.to_flags & TOF_TS) && (to.to_tsecr != 0) &&
bfdb979e
JH
2089 (tp->t_flags & TF_FIRSTACCACK)) {
2090 /* Eifel detection applicable. */
2091 if (to.to_tsecr < tp->t_rexmtTS) {
bfdb979e 2092 ++tcpstat.tcps_eifeldetected;
8819433a
JH
2093 tcp_revert_congestion_state(tp);
2094 if (tp->t_rxtshift == 1 &&
2095 ticks >= tp->t_badrxtwin)
2096 ++tcpstat.tcps_rttcantdetect;
bfdb979e
JH
2097 }
2098 } else if (tp->t_rxtshift == 1 && ticks < tp->t_badrxtwin) {
b5572302
JH
2099 /*
2100 * If we just performed our first retransmit,
2101 * and the ACK arrives within our recovery window,
2102 * then it was a mistake to do the retransmit
91489f6b 2103 * in the first place. Recover our original cwnd
b5572302
JH
2104 * and ssthresh, and proceed to transmit where we
2105 * left off.
2106 */
bfdb979e
JH
2107 tcp_revert_congestion_state(tp);
2108 ++tcpstat.tcps_rttdetected;
984263bc
MD
2109 }
2110
2111 /*
2112 * If we have a timestamp reply, update smoothed
2113 * round trip time. If no timestamp is present but
2114 * transmit timer is running and timed sequence
2115 * number was acked, update smoothed round trip time.
2116 * Since we now have an rtt measurement, cancel the
2117 * timer backoff (cf., Phil Karn's retransmit alg.).
2118 * Recompute the initial retransmit timer.
2119 *
2120 * Some machines (certain windows boxes) send broken
d24ce1dc 2121 * timestamp replies during the SYN+ACK phase, ignore
984263bc
MD
2122 * timestamps of 0.
2123 */
95b22adf 2124 if ((to.to_flags & TOF_TS) && (to.to_tsecr != 0))
984263bc 2125 tcp_xmit_timer(tp, ticks - to.to_tsecr + 1);
95b22adf 2126 else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq))
984263bc 2127 tcp_xmit_timer(tp, ticks - tp->t_rtttime);
984263bc
MD
2128 tcp_xmit_bandwidth_limit(tp, th->th_ack);
2129
984263bc
MD
2130 /*
2131 * If no data (only SYN) was ACK'd,
2132 * skip rest of ACK processing.
2133 */
2134 if (acked == 0)
2135 goto step6;
2136
efd4b327 2137 /* Stop looking for an acceptable ACK since one was received. */
8819433a 2138 tp->t_flags &= ~(TF_FIRSTACCACK | TF_FASTREXMT | TF_EARLYREXMT);
efd4b327 2139
6d49aa6f
MD
2140 if (acked > so->so_snd.ssb_cc) {
2141 tp->snd_wnd -= so->so_snd.ssb_cc;
2142 sbdrop(&so->so_snd.sb, (int)so->so_snd.ssb_cc);
61896e3c 2143 ourfinisacked = TRUE;
984263bc 2144 } else {
6d49aa6f 2145 sbdrop(&so->so_snd.sb, acked);
984263bc 2146 tp->snd_wnd -= acked;
61896e3c 2147 ourfinisacked = FALSE;
984263bc
MD
2148 }
2149 sowwakeup(so);
91489f6b
JH
2150
2151 /*
2152 * Update window information.
2153 * Don't look at window if no ACK:
2154 * TAC's send garbage on first SYN.
2155 */
2156 if (SEQ_LT(tp->snd_wl1, th->th_seq) ||
2157 (tp->snd_wl1 == th->th_seq &&
2158 (SEQ_LT(tp->snd_wl2, th->th_ack) ||
2159 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd)))) {
2160 /* keep track of pure window updates */
2161 if (tlen == 0 && tp->snd_wl2 == th->th_ack &&
2162 tiwin > tp->snd_wnd)
2163 tcpstat.tcps_rcvwinupd++;
2164 tp->snd_wnd = tiwin;
2165 tp->snd_wl1 = th->th_seq;
2166 tp->snd_wl2 = th->th_ack;
2167 if (tp->snd_wnd > tp->max_sndwnd)
2168 tp->max_sndwnd = tp->snd_wnd;
2169 needoutput = TRUE;
2170 }
2171
2172 tp->snd_una = th->th_ack;
2173 if (TCP_DO_SACK(tp))
2174 tcp_sack_update_scoreboard(tp, &to);
95b22adf 2175 if (IN_FASTRECOVERY(tp)) {
91489f6b 2176 if (SEQ_GEQ(th->th_ack, tp->snd_recover)) {
95b22adf 2177 EXIT_FASTRECOVERY(tp);
91489f6b
JH
2178 needoutput = TRUE;
2179 /*
2180 * If the congestion window was inflated
2181 * to account for the other side's
2182 * cached packets, retract it.
8acdb67c
JH
2183 */
2184 if (!TCP_DO_SACK(tp))
2185 tp->snd_cwnd = tp->snd_ssthresh;
2186
2187 /*
91489f6b
JH
2188 * Window inflation should have left us
2189 * with approximately snd_ssthresh outstanding
2190 * data. But, in case we would be inclined
2191 * to send a burst, better do it using
2192 * slow start.
2193 */
91489f6b
JH
2194 if (SEQ_GT(th->th_ack + tp->snd_cwnd,
2195 tp->snd_max + 2 * tp->t_maxseg))
2196 tp->snd_cwnd =
2197 (tp->snd_max - tp->snd_una) +
2198 2 * tp->t_maxseg;
8acdb67c
JH
2199
2200 tp->snd_wacked = 0;
91489f6b
JH
2201 } else {
2202 if (TCP_DO_SACK(tp)) {
2203 tp->snd_max_rexmt = tp->snd_max;
2204 tcp_sack_rexmt(tp, th);
2205 } else {
2206 tcp_newreno_partial_ack(tp, th, acked);
2207 }
2208 needoutput = FALSE;
2209 }
95b22adf 2210 } else {
91489f6b 2211 /*
8acdb67c
JH
2212 * Open the congestion window. When in slow-start,
2213 * open exponentially: maxseg per packet. Otherwise,
2214 * open linearly: maxseg per window.
91489f6b 2215 */
8acdb67c
JH
2216 if (tp->snd_cwnd <= tp->snd_ssthresh) {
2217 u_int abc_sslimit =
2218 (SEQ_LT(tp->snd_nxt, tp->snd_max) ?
2219 tp->t_maxseg : 2 * tp->t_maxseg);
2220
2221 /* slow-start */
2222 tp->snd_cwnd += tcp_do_abc ?
2223 min(acked, abc_sslimit) : tp->t_maxseg;
2224 } else {
2225 /* linear increase */
2226 tp->snd_wacked += tcp_do_abc ? acked :
2227 tp->t_maxseg;
2228 if (tp->snd_wacked >= tp->snd_cwnd) {
2229 tp->snd_wacked -= tp->snd_cwnd;
2230 tp->snd_cwnd += tp->t_maxseg;
2231 }
2232 }
2233 tp->snd_cwnd = min(tp->snd_cwnd,
2234 TCP_MAXWIN << tp->snd_scale);
95b22adf 2235 tp->snd_recover = th->th_ack - 1;
cfb3f3f4 2236 }
984263bc
MD
2237 if (SEQ_LT(tp->snd_nxt, tp->snd_una))
2238 tp->snd_nxt = tp->snd_una;
2239
91489f6b
JH
2240 /*
2241 * If all outstanding data is acked, stop retransmit
2242 * timer and remember to restart (more output or persist).
2243 * If there is more data to be acked, restart retransmit
2244 * timer, using current (possibly backed-off) value.
2245 */
2246 if (th->th_ack == tp->snd_max) {
a48c5dd5 2247 tcp_callout_stop(tp, tp->tt_rexmt);
91489f6b 2248 needoutput = TRUE;
a48c5dd5
SZ
2249 } else if (!tcp_callout_active(tp, tp->tt_persist)) {
2250 tcp_callout_reset(tp, tp->tt_rexmt, tp->t_rxtcur,
2251 tcp_timer_rexmt);
2252 }
91489f6b 2253
984263bc 2254 switch (tp->t_state) {
984263bc
MD
2255 /*
2256 * In FIN_WAIT_1 STATE in addition to the processing
2257 * for the ESTABLISHED state if our FIN is now acknowledged
2258 * then enter FIN_WAIT_2.
2259 */
2260 case TCPS_FIN_WAIT_1:
2261 if (ourfinisacked) {
2262 /*
2263 * If we can't receive any more
2264 * data, then closing user can proceed.
2265 * Starting the timer is contrary to the
2266 * specification, but if we don't get a FIN
2267 * we'll hang forever.
2268 */
2269 if (so->so_state & SS_CANTRCVMORE) {
2270 soisdisconnected(so);
a48c5dd5
SZ
2271 tcp_callout_reset(tp, tp->tt_2msl,
2272 tcp_maxidle, tcp_timer_2msl);
984263bc
MD
2273 }
2274 tp->t_state = TCPS_FIN_WAIT_2;
2275 }
2276 break;
2277
95b22adf 2278 /*
984263bc
MD
2279 * In CLOSING STATE in addition to the processing for
2280 * the ESTABLISHED state if the ACK acknowledges our FIN
2281 * then enter the TIME-WAIT state, otherwise ignore
2282 * the segment.
2283 */
2284 case TCPS_CLOSING:
2285 if (ourfinisacked) {
2286 tp->t_state = TCPS_TIME_WAIT;
2287 tcp_canceltimers(tp);
27b8aee3 2288 tcp_callout_reset(tp, tp->tt_2msl,
a48c5dd5 2289 2 * tcp_msl, tcp_timer_2msl);
984263bc
MD
2290 soisdisconnected(so);
2291 }
2292 break;
2293
2294 /*
2295 * In LAST_ACK, we may still be waiting for data to drain
2296 * and/or to be acked, as well as for the ack of our FIN.
2297 * If our FIN is now acknowledged, delete the TCB,
2298 * enter the closed state and return.
2299 */
2300 case TCPS_LAST_ACK:
2301 if (ourfinisacked) {
2302 tp = tcp_close(tp);
2303 goto drop;
2304 }
2305 break;
2306
2307 /*
2308 * In TIME_WAIT state the only thing that should arrive
2309 * is a retransmission of the remote FIN. Acknowledge
2310 * it and restart the finack timer.
2311 */
2312 case TCPS_TIME_WAIT:
a48c5dd5
SZ
2313 tcp_callout_reset(tp, tp->tt_2msl, 2 * tcp_msl,
2314 tcp_timer_2msl);
984263bc
MD
2315 goto dropafterack;
2316 }
2317 }
2318
2319step6:
2320 /*
2321 * Update window information.
2322 * Don't look at window if no ACK: TAC's send garbage on first SYN.
2323 */
2324 if ((thflags & TH_ACK) &&
df9d7670 2325 acceptable_window_update(tp, th, tiwin)) {
984263bc 2326 /* keep track of pure window updates */
b5572302
JH
2327 if (tlen == 0 && tp->snd_wl2 == th->th_ack &&
2328 tiwin > tp->snd_wnd)
984263bc
MD
2329 tcpstat.tcps_rcvwinupd++;
2330 tp->snd_wnd = tiwin;
2331 tp->snd_wl1 = th->th_seq;
2332 tp->snd_wl2 = th->th_ack;
2333 if (tp->snd_wnd > tp->max_sndwnd)
2334 tp->max_sndwnd = tp->snd_wnd;
61896e3c 2335 needoutput = TRUE;
984263bc
MD
2336 }
2337
2338 /*
2339 * Process segments with URG.
2340 */
2341 if ((thflags & TH_URG) && th->th_urp &&
95b22adf 2342 !TCPS_HAVERCVDFIN(tp->t_state)) {
984263bc
MD
2343 /*
2344 * This is a kludge, but if we receive and accept
2345 * random urgent pointers, we'll crash in
2346 * soreceive. It's hard to imagine someone
2347 * actually wanting to send this much urgent data.
2348 */
6d49aa6f 2349 if (th->th_urp + so->so_rcv.ssb_cc > sb_max) {
984263bc
MD
2350 th->th_urp = 0; /* XXX */
2351 thflags &= ~TH_URG; /* XXX */
2352 goto dodata; /* XXX */
2353 }
2354 /*
2355 * If this segment advances the known urgent pointer,
2356 * then mark the data stream. This should not happen
2357 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since
2358 * a FIN has been received from the remote side.
2359 * In these states we ignore the URG.
2360 *
2361 * According to RFC961 (Assigned Protocols),
2362 * the urgent pointer points to the last octet
2363 * of urgent data. We continue, however,
2364 * to consider it to indicate the first octet
2365 * of data past the urgent section as the original
2366 * spec states (in one of two places).
2367 */
61896e3c 2368 if (SEQ_GT(th->th_seq + th->th_urp, tp->rcv_up)) {
984263bc 2369 tp->rcv_up = th->th_seq + th->th_urp;
6d49aa6f 2370 so->so_oobmark = so->so_rcv.ssb_cc +
984263bc
MD
2371 (tp->rcv_up - tp->rcv_nxt) - 1;
2372 if (so->so_oobmark == 0)
2373 so->so_state |= SS_RCVATMARK;
2374 sohasoutofband(so);
2375 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA);
2376 }
2377 /*
2378 * Remove out of band data so doesn't get presented to user.
2379 * This can happen independent of advancing the URG pointer,
2380 * but if two URG's are pending at once, some out-of-band
2381 * data may creep in... ick.
2382 */
61896e3c
JH
2383 if (th->th_urp <= (u_long)tlen &&
2384 !(so->so_options & SO_OOBINLINE)) {
2385 /* hdr drop is delayed */
2386 tcp_pulloutofband(so, th, m, drop_hdrlen);
2387 }
984263bc
MD
2388 } else {
2389 /*
2390 * If no out of band data is expected,
2391 * pull receive urgent pointer along
2392 * with the receive window.
2393 */
2394 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up))
2395 tp->rcv_up = tp->rcv_nxt;
2396 }
984263bc 2397
61896e3c 2398dodata: /* XXX */
984263bc
MD
2399 /*
2400 * Process the segment text, merging it into the TCP sequencing queue,
2401 * and arranging for acknowledgment of receipt if necessary.
2402 * This process logically involves adjusting tp->rcv_wnd as data
2403 * is presented to the user (this happens in tcp_usrreq.c,
2404 * case PRU_RCVD). If a FIN has already been received on this
2405 * connection then we just ignore the text.
2406 */
95b22adf 2407 if ((tlen || (thflags & TH_FIN)) && !TCPS_HAVERCVDFIN(tp->t_state)) {
984263bc
MD
2408 m_adj(m, drop_hdrlen); /* delayed header drop */
2409 /*
2410 * Insert segment which includes th into TCP reassembly queue
2411 * with control block tp. Set thflags to whether reassembly now
2412 * includes a segment with FIN. This handles the common case
2413 * inline (segment is the next to be received on an established
2414 * connection, and the queue is empty), avoiding linkage into
2415 * and removal from the queue and repetition of various
2416 * conversions.
2417 * Set DELACK for segments received in order, but ack
2418 * immediately when segments are out of order (so
2419 * fast retransmit can work).
2420 */
2421 if (th->th_seq == tp->rcv_nxt &&
2422 LIST_EMPTY(&tp->t_segq) &&
2423 TCPS_HAVEESTABLISHED(tp->t_state)) {
a48c5dd5
SZ
2424 if (DELAY_ACK(tp)) {
2425 tcp_callout_reset(tp, tp->tt_delack,
2426 tcp_delacktime, tcp_timer_delack);
2427 } else {
984263bc 2428 tp->t_flags |= TF_ACKNOW;
a48c5dd5 2429 }
984263bc
MD
2430 tp->rcv_nxt += tlen;
2431 thflags = th->th_flags & TH_FIN;
2432 tcpstat.tcps_rcvpack++;
2433 tcpstat.tcps_rcvbyte += tlen;
2434 ND6_HINT(tp);
2435 if (so->so_state & SS_CANTRCVMORE)
2436 m_freem(m);
2437 else
6d49aa6f 2438 ssb_appendstream(&so->so_rcv, m);
984263bc
MD
2439 sorwakeup(so);
2440 } else {
91489f6b
JH
2441 if (!(tp->t_flags & TF_DUPSEG)) {
2442 /* Initialize SACK report block. */
2443 tp->reportblk.rblk_start = th->th_seq;
2444 tp->reportblk.rblk_end = th->th_seq + tlen +
2445 ((thflags & TH_FIN) != 0);
2446 }
984263bc
MD
2447 thflags = tcp_reass(tp, th, &tlen, m);
2448 tp->t_flags |= TF_ACKNOW;
2449 }
2450
2451 /*
2452 * Note the amount of data that peer has sent into
2453 * our window, in order to estimate the sender's
2454 * buffer size.
2455 */
6d49aa6f 2456 len = so->so_rcv.ssb_hiwat - (tp->rcv_adv - tp->rcv_nxt);
984263bc
MD
2457 } else {
2458 m_freem(m);
2459 thflags &= ~TH_FIN;
2460 }
2461
2462 /*
2463 * If FIN is received ACK the FIN and let the user know
2464 * that the connection is closing.
2465 */
2466 if (thflags & TH_FIN) {
95b22adf 2467 if (!TCPS_HAVERCVDFIN(tp->t_state)) {
984263bc
MD
2468 socantrcvmore(so);
2469 /*
2470 * If connection is half-synchronized
2471 * (ie NEEDSYN flag on) then delay ACK,
2472 * so it may be piggybacked when SYN is sent.
2473 * Otherwise, since we received a FIN then no
2474 * more input can be expected, send ACK now.
2475 */
a48c5dd5
SZ
2476 if (DELAY_ACK(tp) && (tp->t_flags & TF_NEEDSYN)) {
2477 tcp_callout_reset(tp, tp->tt_delack,
2478 tcp_delacktime, tcp_timer_delack);
2479 } else {
984263bc 2480 tp->t_flags |= TF_ACKNOW;
a48c5dd5 2481 }
984263bc
MD
2482 tp->rcv_nxt++;
2483 }
984263bc 2484
61896e3c 2485 switch (tp->t_state) {
95b22adf 2486 /*
984263bc
MD
2487 * In SYN_RECEIVED and ESTABLISHED STATES
2488 * enter the CLOSE_WAIT state.
2489 */
2490 case TCPS_SYN_RECEIVED:
2491 tp->t_starttime = ticks;
2492 /*FALLTHROUGH*/
2493 case TCPS_ESTABLISHED:
2494 tp->t_state = TCPS_CLOSE_WAIT;
2495 break;
2496
95b22adf 2497 /*
984263bc
MD
2498 * If still in FIN_WAIT_1 STATE FIN has not been acked so
2499 * enter the CLOSING state.
2500 */
2501 case TCPS_FIN_WAIT_1:
2502 tp->t_state = TCPS_CLOSING;
2503 break;
2504
95b22adf 2505 /*
984263bc
MD
2506 * In FIN_WAIT_2 state enter the TIME_WAIT state,
2507 * starting the time-wait timer, turning off the other
2508 * standard timers.
2509 */
2510 case TCPS_FIN_WAIT_2:
2511 tp->t_state = TCPS_TIME_WAIT;
2512 tcp_canceltimers(tp);
27b8aee3 2513 tcp_callout_reset(tp, tp->tt_2msl, 2 * tcp_msl,
a48c5dd5 2514 tcp_timer_2msl);
984263bc
MD
2515 soisdisconnected(so);
2516 break;
2517
2518 /*
2519 * In TIME_WAIT state restart the 2 MSL time_wait timer.
2520 */
2521 case TCPS_TIME_WAIT:
a48c5dd5
SZ
2522 tcp_callout_reset(tp, tp->tt_2msl, 2 * tcp_msl,
2523 tcp_timer_2msl);
984263bc
MD
2524 break;
2525 }
2526 }
61896e3c 2527
984263bc
MD
2528#ifdef TCPDEBUG
2529 if (so->so_options & SO_DEBUG)
f23061d4 2530 tcp_trace(TA_INPUT, ostate, tp, tcp_saveipgen, &tcp_savetcp, 0);
984263bc
MD
2531#endif
2532
2533 /*
2534 * Return any desired output.
2535 */
2536 if (needoutput || (tp->t_flags & TF_ACKNOW))
f23061d4 2537 tcp_output(tp);
984263bc
MD
2538 return;
2539
2540dropafterack:
2541 /*
2542 * Generate an ACK dropping incoming segment if it occupies
2543 * sequence space, where the ACK reflects our state.
2544 *
2545 * We can now skip the test for the RST flag since all
2546 * paths to this code happen after packets containing
2547 * RST have been dropped.
2548 *
2549 * In the SYN-RECEIVED state, don't send an ACK unless the
2550 * segment we received passes the SYN-RECEIVED ACK test.
2551 * If it fails send a RST. This breaks the loop in the
2552 * "LAND" DoS attack, and also prevents an ACK storm
2553 * between two listening ports that have been sent forged
2554 * SYN segments, each with the source address of the other.
2555 */
2556 if (tp->t_state == TCPS_SYN_RECEIVED && (thflags & TH_ACK) &&
2557 (SEQ_GT(tp->snd_una, th->th_ack) ||
2558 SEQ_GT(th->th_ack, tp->snd_max)) ) {
2559 rstreason = BANDLIM_RST_OPENPORT;
2560 goto dropwithreset;
2561 }
2562#ifdef TCPDEBUG
2563 if (so->so_options & SO_DEBUG)
f23061d4 2564 tcp_trace(TA_DROP, ostate, tp, tcp_saveipgen, &tcp_savetcp, 0);
984263bc
MD
2565#endif
2566 m_freem(m);
2567 tp->t_flags |= TF_ACKNOW;
f23061d4 2568 tcp_output(tp);
984263bc
MD
2569 return;
2570
2571dropwithreset:
2572 /*
2573 * Generate a RST, dropping incoming segment.
2574 * Make ACK acceptable to originator of segment.
2575 * Don't bother to respond if destination was broadcast/multicast.
2576 */
61896e3c 2577 if ((thflags & TH_RST) || m->m_flags & (M_BCAST | M_MCAST))
984263bc
MD
2578 goto drop;
2579 if (isipv6) {
2580 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
2581 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src))
2582 goto drop;
2583 } else {
2584 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) ||
2585 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
95b22adf
JH
2586 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) ||
2587 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif))
984263bc
MD
2588 goto drop;
2589 }
2590 /* IPv6 anycast check is done at tcp6_input() */
2591
2592 /*
2593 * Perform bandwidth limiting.
2594 */
2595#ifdef ICMP_BANDLIM
2596 if (badport_bandlim(rstreason) < 0)
2597 goto drop;
2598#endif
2599
2600#ifdef TCPDEBUG
2601 if (tp == NULL || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
f23061d4 2602 tcp_trace(TA_DROP, ostate, tp, tcp_saveipgen, &tcp_savetcp, 0);
984263bc
MD
2603#endif
2604 if (thflags & TH_ACK)
2605 /* mtod() below is safe as long as hdr dropping is delayed */
2606 tcp_respond(tp, mtod(m, void *), th, m, (tcp_seq)0, th->th_ack,
2607 TH_RST);
2608 else {
2609 if (thflags & TH_SYN)
2610 tlen++;
2611 /* mtod() below is safe as long as hdr dropping is delayed */
61896e3c
JH
2612 tcp_respond(tp, mtod(m, void *), th, m, th->th_seq + tlen,
2613 (tcp_seq)0, TH_RST | TH_ACK);
984263bc
MD
2614 }
2615 return;
2616
2617drop:
2618 /*
2619 * Drop space held by incoming segment and return.
2620 */
2621#ifdef TCPDEBUG
2622 if (tp == NULL || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
f23061d4 2623 tcp_trace(TA_DROP, ostate, tp, tcp_saveipgen, &tcp_savetcp, 0);
984263bc
MD
2624#endif
2625 m_freem(m);
2626 return;
2627}
2628
2629/*
2630 * Parse TCP options and place in tcpopt.
2631 */
2632static void
95b22adf 2633tcp_dooptions(struct tcpopt *to, u_char *cp, int cnt, boolean_t is_syn)
984263bc 2634{
91489f6b 2635 int opt, optlen, i;
984263bc
MD
2636
2637 to->to_flags = 0;
2638 for (; cnt > 0; cnt -= optlen, cp += optlen) {
2639 opt = cp[0];
2640 if (opt == TCPOPT_EOL)
2641 break;
2642 if (opt == TCPOPT_NOP)
2643 optlen = 1;
2644 else {
2645 if (cnt < 2)
2646 break;
2647 optlen = cp[1];
2648 if (optlen < 2 || optlen > cnt)
2649 break;
2650 }
2651 switch (opt) {
2652 case TCPOPT_MAXSEG:
2653 if (optlen != TCPOLEN_MAXSEG)
2654 continue;
2655 if (!is_syn)
2656 continue;
2657 to->to_flags |= TOF_MSS;
407e896e 2658 bcopy(cp + 2, &to->to_mss, sizeof to->to_mss);
984263bc
MD
2659 to->to_mss = ntohs(to->to_mss);
2660 break;
2661 case TCPOPT_WINDOW:
2662 if (optlen != TCPOLEN_WINDOW)
2663 continue;
95b22adf 2664 if (!is_syn)
984263bc
MD
2665 continue;
2666 to->to_flags |= TOF_SCALE;
2667 to->to_requested_s_scale = min(cp[2], TCP_MAX_WINSHIFT);
2668 break;
2669 case TCPOPT_TIMESTAMP:
2670 if (optlen != TCPOLEN_TIMESTAMP)
2671 continue;
2672 to->to_flags |= TOF_TS;
407e896e 2673 bcopy(cp + 2, &to->to_tsval, sizeof to->to_tsval);
984263bc 2674 to->to_tsval = ntohl(to->to_tsval);
407e896e 2675 bcopy(cp + 6, &to->to_tsecr, sizeof to->to_tsecr);
984263bc 2676 to->to_tsecr = ntohl(to->to_tsecr);
ad0af98b
ND
2677 /*
2678 * If echoed timestamp is later than the current time,
2679 * fall back to non RFC1323 RTT calculation.
2680 */
2681 if (to->to_tsecr != 0 && TSTMP_GT(to->to_tsecr, ticks))
2682 to->to_tsecr = 0;
984263bc 2683 break;
91489f6b
JH
2684 case TCPOPT_SACK_PERMITTED:
2685 if (optlen != TCPOLEN_SACK_PERMITTED)
2686 continue;
2687 if (!is_syn)
2688 continue;
2689 to->to_flags |= TOF_SACK_PERMITTED;
2690 break;
2691 case TCPOPT_SACK:
2692 if ((optlen - 2) & 0x07) /* not multiple of 8 */
2693 continue;
2694 to->to_nsackblocks = (optlen - 2) / 8;
2695 to->to_sackblocks = (struct raw_sackblock *) (cp + 2);
2696 to->to_flags |= TOF_SACK;
2697 for (i = 0; i < to->to_nsackblocks; i++) {
2698 struct raw_sackblock *r = &to->to_sackblocks[i];
2699
2700 r->rblk_start = ntohl(r->rblk_start);
2701 r->rblk_end = ntohl(r->rblk_end);
2702 }
2703 break;
984263bc
MD
2704 default:
2705 continue;
2706 }
2707 }
2708}
2709
2710/*
2711 * Pull out of band byte out of a segment so
2712 * it doesn't appear in the user's data queue.
2713 * It is still reflected in the segment length for
2714 * sequencing purposes.
95b22adf 2715 * "off" is the delayed to be dropped hdrlen.
984263bc
MD
2716 */
2717static void
95b22adf 2718tcp_pulloutofband(struct socket *so, struct tcphdr *th, struct mbuf *m, int off)
984263bc
MD
2719{
2720 int cnt = off + th->th_urp - 1;
2721
2722 while (cnt >= 0) {
2723 if (m->m_len > cnt) {
2724 char *cp = mtod(m, caddr_t) + cnt;
2725 struct tcpcb *tp = sototcpcb(so);
2726
2727 tp->t_iobc = *cp;
2728 tp->t_oobflags |= TCPOOB_HAVEDATA;
95b22adf 2729 bcopy(cp + 1, cp, m->m_len - cnt - 1);
984263bc
MD
2730 m->m_len--;
2731 if (m->m_flags & M_PKTHDR)
2732 m->m_pkthdr.len--;
2733 return;
2734 }
2735 cnt -= m->m_len;
2736 m = m->m_next;
2737 if (m == 0)
2738 break;
2739 }
2740 panic("tcp_pulloutofband");
2741}
2742
2743/*
2744 * Collect new round-trip time estimate
2745 * and update averages and current timeout.
2746 */
2747static void
95b22adf 2748tcp_xmit_timer(struct tcpcb *tp, int rtt)
984263bc 2749{
2256ba69 2750 int delta;
984263bc
MD
2751
2752 tcpstat.tcps_rttupdated++;
2753 tp->t_rttupdated++;
2754 if (tp->t_srtt != 0) {
2755 /*
2756 * srtt is stored as fixed point with 5 bits after the
2757 * binary point (i.e., scaled by 8). The following magic
2758 * is equivalent to the smoothing algorithm in rfc793 with
2759 * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed
2760 * point). Adjust rtt to origin 0.
2761 */
2762 delta = ((rtt - 1) << TCP_DELTA_SHIFT)
2763 - (tp->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT));
2764
2765 if ((tp->t_srtt += delta) <= 0)
2766 tp->t_srtt = 1;
2767
2768 /*
2769 * We accumulate a smoothed rtt variance (actually, a
2770 * smoothed mean difference), then set the retransmit
2771 * timer to smoothed rtt + 4 times the smoothed variance.
2772 * rttvar is stored as fixed point with 4 bits after the
2773 * binary point (scaled by 16). The following is
2774 * equivalent to rfc793 smoothing with an alpha of .75
2775 * (rttvar = rttvar*3/4 + |delta| / 4). This replaces
2776 * rfc793's wired-in beta.
2777 */
2778 if (delta < 0)
2779 delta = -delta;
2780 delta -= tp->t_rttvar >> (TCP_RTTVAR_SHIFT - TCP_DELTA_SHIFT);
2781 if ((tp->t_rttvar += delta) <= 0)
2782 tp->t_rttvar = 1;
2783 if (tp->t_rttbest > tp->t_srtt + tp->t_rttvar)
2784 tp->t_rttbest = tp->t_srtt + tp->t_rttvar;
2785 } else {
2786 /*
2787 * No rtt measurement yet - use the unsmoothed rtt.
2788 * Set the variance to half the rtt (so our first
2789 * retransmit happens at 3*rtt).
2790 */
2791 tp->t_srtt = rtt << TCP_RTT_SHIFT;
2792 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1);
2793 tp->t_rttbest = tp->t_srtt + tp->t_rttvar;
2794 }
2795 tp->t_rtttime = 0;
2796 tp->t_rxtshift = 0;
2797
2798 /*
2799 * the retransmit should happen at rtt + 4 * rttvar.
2800 * Because of the way we do the smoothing, srtt and rttvar
2801 * will each average +1/2 tick of bias. When we compute
2802 * the retransmit timer, we want 1/2 tick of rounding and
2803 * 1 extra tick because of +-1/2 tick uncertainty in the
2804 * firing of the timer. The bias will give us exactly the
2805 * 1.5 tick we need. But, because the bias is
2806 * statistical, we have to test that we don't drop below
2807 * the minimum feasible timer (which is 2 ticks).
2808 */
2809 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp),
2810 max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX);
2811
2812 /*
2813 * We received an ack for a packet that wasn't retransmitted;
2814 * it is probably safe to discard any error indications we've
2815 * received recently. This isn't quite right, but close enough
2816 * for now (a route might have failed after we sent a segment,
2817 * and the return path might not be symmetrical).
2818 */
2819 tp->t_softerror = 0;
2820}
2821
2822/*
2823 * Determine a reasonable value for maxseg size.
2824 * If the route is known, check route for mtu.
2825 * If none, use an mss that can be handled on the outgoing
2826 * interface without forcing IP to fragment; if bigger than
2827 * an mbuf cluster (MCLBYTES), round down to nearest multiple of MCLBYTES
2828 * to utilize large mbufs. If no route is found, route has no mtu,
2829 * or the destination isn't local, use a default, hopefully conservative
2830 * size (usually 512 or the default IP max size, but no more than the mtu
2831 * of the interface), as we can't discover anything about intervening
2832 * gateways or networks. We also initialize the congestion/slow start
2833 * window to be a single segment if the destination isn't local.
2834 * While looking at the routing entry, we also initialize other path-dependent
2835 * parameters from pre-set or cached values in the routing entry.
2836 *
2837 * Also take into account the space needed for options that we
2838 * send regularly. Make maxseg shorter by that amount to assure
2839 * that we can send maxseg amount of data even when the options
2840 * are present. Store the upper limit of the length of options plus
2841 * data in maxopd.
2842 *
2843 * NOTE that this routine is only called when we process an incoming
2844 * segment, for outgoing segments only tcp_mssopt is called.
984263bc
MD
2845 */
2846void
95b22adf 2847tcp_mss(struct tcpcb *tp, int offer)
984263bc 2848{
2256ba69 2849 struct rtentry *rt;
984263bc 2850 struct ifnet *ifp;
2256ba69 2851 int rtt, mss;
984263bc
MD
2852 u_long bufsize;
2853 struct inpcb *inp = tp->t_inpcb;
2854 struct socket *so;
984263bc 2855#ifdef INET6
d24ce1dc 2856 boolean_t isipv6 = ((inp->inp_vflag & INP_IPV6) ? TRUE : FALSE);
984263bc
MD
2857 size_t min_protoh = isipv6 ?
2858 sizeof(struct ip6_hdr) + sizeof(struct tcphdr) :
2859 sizeof(struct tcpiphdr);
2860#else
d24ce1dc 2861 const boolean_t isipv6 = FALSE;
984263bc
MD
2862 const size_t min_protoh = sizeof(struct tcpiphdr);
2863#endif
2864
2865 if (isipv6)
2866 rt = tcp_rtlookup6(&inp->inp_inc);
2867 else
2868 rt = tcp_rtlookup(&inp->inp_inc);
2869 if (rt == NULL) {
2870 tp->t_maxopd = tp->t_maxseg =
d24ce1dc 2871 (isipv6 ? tcp_v6mssdflt : tcp_mssdflt);
984263bc
MD
2872 return;
2873 }
2874 ifp = rt->rt_ifp;
2875 so = inp->inp_socket;
2876
984263bc
MD
2877 /*
2878 * Offer == 0 means that there was no MSS on the SYN segment,
b235ad6d
MD
2879 * in this case we use either the interface mtu or tcp_mssdflt.
2880 *
2881 * An offer which is too large will be cut down later.
984263bc 2882 */
5b0b9fa5 2883 if (offer == 0) {
b235ad6d
MD
2884 if (isipv6) {
2885 if (in6_localaddr(&inp->in6p_faddr)) {
2886 offer = ND_IFINFO(rt->rt_ifp)->linkmtu -
2887 min_protoh;
2888 } else {
2889 offer = tcp_v6mssdflt;
2890 }
2891 } else {
2892 if (in_localaddr(inp->inp_faddr))
2893 offer = ifp->if_mtu - min_protoh;
2894 else
2895 offer = tcp_mssdflt;
2896 }
5b0b9fa5 2897 }
b235ad6d
MD
2898
2899 /*
2900 * Prevent DoS attack with too small MSS. Round up
2901 * to at least minmss.
2902 *
2903 * Sanity check: make sure that maxopd will be large
2904 * enough to allow some data on segments even is the
2905 * all the option space is used (40bytes). Otherwise
2906 * funny things may happen in tcp_output.
2907 */
2908 offer = max(offer, tcp_minmss);
2909 offer = max(offer, 64);
2910
27b8aee3 2911 rt->rt_rmx.rmx_mssopt = offer;
984263bc
MD
2912
2913 /*
2914 * While we're here, check if there's an initial rtt
2915 * or rttvar. Convert from the route-table units
2916 * to scaled multiples of the slow timeout timer.
2917 */
2918 if (tp->t_srtt == 0 && (rtt = rt->rt_rmx.rmx_rtt)) {
2919 /*
2920 * XXX the lock bit for RTT indicates that the value
2921 * is also a minimum value; this is subject to time.
2922 */
2923 if (rt->rt_rmx.rmx_locks & RTV_RTT)
2924 tp->t_rttmin = rtt / (RTM_RTTUNIT / hz);
2925 tp->t_srtt = rtt / (RTM_RTTUNIT / (hz * TCP_RTT_SCALE));
2926 tp->t_rttbest = tp->t_srtt + TCP_RTT_SCALE;
2927 tcpstat.tcps_usedrtt++;
2928 if (rt->rt_rmx.rmx_rttvar) {
2929 tp->t_rttvar = rt->rt_rmx.rmx_rttvar /
2930 (RTM_RTTUNIT / (hz * TCP_RTTVAR_SCALE));
2931 tcpstat.tcps_usedrttvar++;
2932 } else {
2933 /* default variation is +- 1 rtt */
2934 tp->t_rttvar =
2935 tp->t_srtt * TCP_RTTVAR_SCALE / TCP_RTT_SCALE;
2936 }
2937 TCPT_RANGESET(tp->t_rxtcur,
2938 ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1,
2939 tp->t_rttmin, TCPTV_REXMTMAX);
2940 }
b235ad6d 2941
984263bc
MD
2942 /*
2943 * if there's an mtu associated with the route, use it
b235ad6d
MD
2944 * else, use the link mtu. Take the smaller of mss or offer
2945 * as our final mss.
984263bc 2946 */
b235ad6d 2947 if (rt->rt_rmx.rmx_mtu) {
984263bc 2948 mss = rt->rt_rmx.rmx_mtu - min_protoh;
b235ad6d
MD
2949 } else {
2950 if (isipv6)
698ac46c 2951 mss = ND_IFINFO(rt->rt_ifp)->linkmtu - min_protoh;
b235ad6d 2952 else
984263bc 2953 mss = ifp->if_mtu - min_protoh;
984263bc
MD
2954 }
2955 mss = min(mss, offer);
b235ad6d 2956
984263bc
MD
2957 /*
2958 * maxopd stores the maximum length of data AND options
2959 * in a segment; maxseg is the amount of data in a normal
2960 * segment. We need to store this value (maxopd) apart
2961 * from maxseg, because now every segment carries options
2962 * and thus we normally have somewhat less data in segments.
2963 */
2964 tp->t_maxopd = mss;
2965
61896e3c 2966 if ((tp->t_flags & (TF_REQ_TSTMP | TF_NOOPT)) == TF_REQ_TSTMP &&
27b8aee3 2967 ((tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP))
984263bc 2968 mss -= TCPOLEN_TSTAMP_APPA;
984263bc
MD
2969
2970#if (MCLBYTES & (MCLBYTES - 1)) == 0
2971 if (mss > MCLBYTES)
2972 mss &= ~(MCLBYTES-1);
2973#else
2974 if (mss > MCLBYTES)
2975 mss = mss / MCLBYTES * MCLBYTES;
2976#endif
2977 /*
2978 * If there's a pipesize, change the socket buffer
2979 * to that size. Make the socket buffers an integral
2980 * number of mss units; if the mss is larger than
2981 * the socket buffer, decrease the mss.
2982 */
2983#ifdef RTV_SPIPE
2984 if ((bufsize = rt->rt_rmx.rmx_sendpipe) == 0)
2985#endif
6d49aa6f 2986 bufsize = so->so_snd.ssb_hiwat;
984263bc
MD
2987 if (bufsize < mss)
2988 mss = bufsize;
2989 else {
2990 bufsize = roundup(bufsize, mss);
2991 if (bufsize > sb_max)
2992 bufsize = sb_max;
6d49aa6f
MD
2993 if (bufsize > so->so_snd.ssb_hiwat)
2994 ssb_reserve(&so->so_snd, bufsize, so, NULL);
984263bc
MD
2995 }
2996 tp->t_maxseg = mss;
2997
2998#ifdef RTV_RPIPE
2999 if ((bufsize = rt->rt_rmx.rmx_recvpipe) == 0)
3000#endif
6d49aa6f 3001 bufsize = so->so_rcv.ssb_hiwat;
984263bc
MD
3002 if (bufsize > mss) {
3003 bufsize = roundup(bufsize, mss);
3004 if (bufsize > sb_max)
3005 bufsize = sb_max;
6d49aa6f
MD
3006 if (bufsize > so->so_rcv.ssb_hiwat)
3007 ssb_reserve(&so->so_rcv, bufsize, so, NULL);
984263bc
MD
3008 }
3009
3010 /*
3011 * Set the slow-start flight size depending on whether this
3012 * is a local network or not.
3013 */
4b52d5ee
JH
3014 if (tcp_do_rfc3390)
3015 tp->snd_cwnd = min(4 * mss, max(2 * mss, 4380));
4b52d5ee 3016 else
cd149066 3017 tp->snd_cwnd = mss;
984263bc
MD
3018
3019 if (rt->rt_rmx.rmx_ssthresh) {
3020 /*
3021 * There's some sort of gateway or interface
3022 * buffer limit on the path. Use this to set
3023 * the slow start threshhold, but set the
3024 * threshold to no less than 2*mss.
3025 */
3026 tp->snd_ssthresh = max(2 * mss, rt->rt_rmx.rmx_ssthresh);
3027 tcpstat.tcps_usedssthresh++;
3028 }
3029}
3030
3031/*
3032 * Determine the MSS option to send on an outgoing SYN.
3033 */
3034int
95b22adf 3035tcp_mssopt(struct tcpcb *tp)
984263bc
MD
3036{
3037 struct rtentry *rt;
3038#ifdef INET6
d24ce1dc
JH
3039 boolean_t isipv6 =
3040 ((tp->t_inpcb->inp_vflag & INP_IPV6) ? TRUE : FALSE);
984263bc
MD
3041 int min_protoh = isipv6 ?
3042 sizeof(struct ip6_hdr) + sizeof(struct tcphdr) :
3043 sizeof(struct tcpiphdr);
3044#else
d24ce1dc 3045 const boolean_t isipv6 = FALSE;
984263bc
MD
3046 const size_t min_protoh = sizeof(struct tcpiphdr);
3047#endif
3048
3049 if (isipv6)
3050 rt = tcp_rtlookup6(&tp->t_inpcb->inp_inc);
3051 else
3052 rt = tcp_rtlookup(&tp->t_inpcb->inp_inc);
3053 if (rt == NULL)
3054 return (isipv6 ? tcp_v6mssdflt : tcp_mssdflt);
3055
3056 return (rt->rt_ifp->if_mtu - min_protoh);
3057}
3058
984263bc
MD
3059/*
3060 * When a partial ack arrives, force the retransmission of the
91489f6b
JH
3061 * next unacknowledged segment. Do not exit Fast Recovery.
3062 *
3063 * Implement the Slow-but-Steady variant of NewReno by restarting the
3064 * the retransmission timer. Turn it off here so it can be restarted
3065 * later in tcp_output().
984263bc
MD
3066 */
3067static void
91489f6b 3068tcp_newreno_partial_ack(struct tcpcb *tp, struct tcphdr *th, int acked)
984263bc 3069{
91489f6b
JH
3070 tcp_seq old_snd_nxt = tp->snd_nxt;
3071 u_long ocwnd = tp->snd_cwnd;
984263bc 3072
a48c5dd5 3073 tcp_callout_stop(tp, tp->tt_rexmt);
984263bc
MD
3074 tp->t_rtttime = 0;
3075 tp->snd_nxt = th->th_ack;
91489f6b
JH
3076 /* Set snd_cwnd to one segment beyond acknowledged offset. */
3077 tp->snd_cwnd = tp->t_maxseg;
984263bc 3078 tp->t_flags |= TF_ACKNOW;
f23061d4 3079 tcp_output(tp);
91489f6b
JH
3080 if (SEQ_GT(old_snd_nxt, tp->snd_nxt))
3081 tp->snd_nxt = old_snd_nxt;
3082 /* partial window deflation */
68947d12
ND
3083 if (ocwnd > acked)
3084 tp->snd_cwnd = ocwnd - acked + tp->t_maxseg;
3085 else
3086 tp->snd_cwnd = tp->t_maxseg;
91489f6b
JH
3087}
3088
3089/*
3090 * In contrast to the Slow-but-Steady NewReno variant,
3091 * we do not reset the retransmission timer for SACK retransmissions,
3092 * except when retransmitting snd_una.
3093 */
3094static void
3095tcp_sack_rexmt(struct tcpcb *tp, struct tcphdr *th)
3096{
3097 uint32_t pipe, seglen;
3098 tcp_seq nextrexmt;
3099 boolean_t lostdup;
3100 tcp_seq old_snd_nxt = tp->snd_nxt;
3101 u_long ocwnd = tp->snd_cwnd;
3102 int nseg = 0; /* consecutive new segments */
3103#define MAXBURST 4 /* limit burst of new packets on partial ack */
3104
3105 tp->t_rtttime = 0;
3106 pipe = tcp_sack_compute_pipe(tp);
3107 while ((tcp_seq_diff_t)(ocwnd - pipe) >= (tcp_seq_diff_t)tp->t_maxseg &&
3108 (!tcp_do_smartsack || nseg < MAXBURST) &&
3109 tcp_sack_nextseg(tp, &nextrexmt, &seglen, &lostdup)) {
3110 uint32_t sent;
3111 tcp_seq old_snd_max;
3112 int error;
3113
98cb2337
MD
3114 if (nextrexmt == tp->snd_max)
3115 ++nseg;
91489f6b
JH
3116 tp->snd_nxt = nextrexmt;
3117 tp->snd_cwnd = nextrexmt - tp->snd_una + seglen;
3118 old_snd_max = tp->snd_max;
3119 if (nextrexmt == tp->snd_una)
a48c5dd5 3120 tcp_callout_stop(tp, tp->tt_rexmt);
91489f6b
JH
3121 error = tcp_output(tp);
3122 if (error != 0)
3123 break;
3124 sent = tp->snd_nxt - nextrexmt;
3125 if (sent <= 0)
3126 break;
3127 if (!lostdup)
3128 pipe += sent;
3129 tcpstat.tcps_sndsackpack++;
3130 tcpstat.tcps_sndsackbyte += sent;
3131 if (SEQ_LT(nextrexmt, old_snd_max) &&
3132 SEQ_LT(tp->rexmt_high, tp->snd_nxt))
3133 tp->rexmt_high = seq_min(tp->snd_nxt, old_snd_max);
3134 }
3135 if (SEQ_GT(old_snd_nxt, tp->snd_nxt))
3136 tp->snd_nxt = old_snd_nxt;
984263bc 3137 tp->snd_cwnd = ocwnd;
984263bc 3138}