Fix whitespace.
[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 *
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5 * This code is derived from software contributed to The DragonFly Project
6 * by Jeffrey M. Hsu.
95b22adf 7 *
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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
34/*
35 * Copyright (c) 2002, 2003, 2004 Jeffrey M. Hsu. All rights reserved.
36 *
37 * License terms: all terms for the DragonFly license above plus the following:
38 *
39 * 4. All advertising materials mentioning features or use of this software
40 * must display the following acknowledgement:
41 *
42 * This product includes software developed by Jeffrey M. Hsu
43 * for the DragonFly Project.
44 *
45 * This requirement may be waived with permission from Jeffrey Hsu.
46 * This requirement will sunset and may be removed on July 8 2005,
47 * after which the standard DragonFly license (as shown above) will
48 * apply.
49 */
50
51/*
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52 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995
53 * The Regents of the University of California. All rights reserved.
54 *
55 * Redistribution and use in source and binary forms, with or without
56 * modification, are permitted provided that the following conditions
57 * are met:
58 * 1. Redistributions of source code must retain the above copyright
59 * notice, this list of conditions and the following disclaimer.
60 * 2. Redistributions in binary form must reproduce the above copyright
61 * notice, this list of conditions and the following disclaimer in the
62 * documentation and/or other materials provided with the distribution.
63 * 3. All advertising materials mentioning features or use of this software
64 * must display the following acknowledgement:
65 * This product includes software developed by the University of
66 * California, Berkeley and its contributors.
67 * 4. Neither the name of the University nor the names of its contributors
68 * may be used to endorse or promote products derived from this software
69 * without specific prior written permission.
70 *
71 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
72 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
73 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
74 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
75 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
76 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
77 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
78 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
79 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
80 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
81 * SUCH DAMAGE.
82 *
83 * @(#)tcp_input.c 8.12 (Berkeley) 5/24/95
84 * $FreeBSD: src/sys/netinet/tcp_input.c,v 1.107.2.38 2003/05/21 04:46:41 cjc Exp $
507106e0 85 * $DragonFly: src/sys/netinet/tcp_input.c,v 1.45 2004/12/08 23:59:01 hsu Exp $
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86 */
87
88#include "opt_ipfw.h" /* for ipfw_fwd */
89#include "opt_inet6.h"
90#include "opt_ipsec.h"
91#include "opt_tcpdebug.h"
92#include "opt_tcp_input.h"
93
94#include <sys/param.h>
95#include <sys/systm.h>
96#include <sys/kernel.h>
97#include <sys/sysctl.h>
98#include <sys/malloc.h>
99#include <sys/mbuf.h>
100#include <sys/proc.h> /* for proc0 declaration */
101#include <sys/protosw.h>
102#include <sys/socket.h>
103#include <sys/socketvar.h>
104#include <sys/syslog.h>
3f9db7f8 105#include <sys/in_cksum.h>
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106
107#include <machine/cpu.h> /* before tcp_seq.h, for tcp_random18() */
a00138cb 108#include <machine/stdarg.h>
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109
110#include <net/if.h>
111#include <net/route.h>
112
113#include <netinet/in.h>
114#include <netinet/in_systm.h>
115#include <netinet/ip.h>
95b22adf 116#include <netinet/ip_icmp.h> /* for ICMP_BANDLIM */
984263bc 117#include <netinet/in_var.h>
95b22adf 118#include <netinet/icmp_var.h> /* for ICMP_BANDLIM */
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119#include <netinet/in_pcb.h>
120#include <netinet/ip_var.h>
121#include <netinet/ip6.h>
122#include <netinet/icmp6.h>
123#include <netinet6/nd6.h>
124#include <netinet6/ip6_var.h>
125#include <netinet6/in6_pcb.h>
126#include <netinet/tcp.h>
127#include <netinet/tcp_fsm.h>
128#include <netinet/tcp_seq.h>
129#include <netinet/tcp_timer.h>
130#include <netinet/tcp_var.h>
131#include <netinet6/tcp6_var.h>
132#include <netinet/tcpip.h>
95b22adf 133
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134#ifdef TCPDEBUG
135#include <netinet/tcp_debug.h>
136
95b22adf 137u_char tcp_saveipgen[40]; /* the size must be of max ip header, now IPv6 */
984263bc 138struct tcphdr tcp_savetcp;
95b22adf 139#endif
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140
141#ifdef FAST_IPSEC
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142#include <netproto/ipsec/ipsec.h>
143#include <netproto/ipsec/ipsec6.h>
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144#endif
145
146#ifdef IPSEC
147#include <netinet6/ipsec.h>
148#include <netinet6/ipsec6.h>
d2438d69 149#include <netproto/key/key.h>
95b22adf 150#endif
984263bc 151
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152MALLOC_DEFINE(M_TSEGQ, "tseg_qent", "TCP segment queue entry");
153
984263bc 154tcp_cc tcp_ccgen;
984263bc 155static int log_in_vain = 0;
d24ce1dc 156SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_in_vain, CTLFLAG_RW,
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157 &log_in_vain, 0, "Log all incoming TCP connections");
158
159static int blackhole = 0;
160SYSCTL_INT(_net_inet_tcp, OID_AUTO, blackhole, CTLFLAG_RW,
161 &blackhole, 0, "Do not send RST when dropping refused connections");
162
163int tcp_delack_enabled = 1;
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164SYSCTL_INT(_net_inet_tcp, OID_AUTO, delayed_ack, CTLFLAG_RW,
165 &tcp_delack_enabled, 0,
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166 "Delay ACK to try and piggyback it onto a data packet");
167
168#ifdef TCP_DROP_SYNFIN
169static int drop_synfin = 0;
170SYSCTL_INT(_net_inet_tcp, OID_AUTO, drop_synfin, CTLFLAG_RW,
171 &drop_synfin, 0, "Drop TCP packets with SYN+FIN set");
172#endif
173
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174static int tcp_do_limitedtransmit = 1;
175SYSCTL_INT(_net_inet_tcp, OID_AUTO, limitedtransmit, CTLFLAG_RW,
176 &tcp_do_limitedtransmit, 0, "Enable RFC 3042 (Limited Transmit)");
177
91489f6b 178static int tcp_do_early_retransmit = 1;
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179SYSCTL_INT(_net_inet_tcp, OID_AUTO, earlyretransmit, CTLFLAG_RW,
180 &tcp_do_early_retransmit, 0, "Early retransmit");
181
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182static int tcp_do_rfc3390 = 1;
183SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc3390, CTLFLAG_RW,
184 &tcp_do_rfc3390, 0,
185 "Enable RFC 3390 (Increasing TCP's Initial Congestion Window)");
186
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187static int tcp_do_eifel_detect = 1;
188SYSCTL_INT(_net_inet_tcp, OID_AUTO, eifel, CTLFLAG_RW,
189 &tcp_do_eifel_detect, 0, "Eifel detection algorithm (RFC 3522)");
190
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191/*
192 * Define as tunable for easy testing with SACK on and off.
193 * Warning: do not change setting in the middle of an existing active TCP flow,
194 * else strange things might happen to that flow.
195 */
6e5bbdda 196int tcp_do_sack = 1;
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197SYSCTL_INT(_net_inet_tcp, OID_AUTO, sack, CTLFLAG_RW,
198 &tcp_do_sack, 0, "Enable SACK Algorithms");
199
200int tcp_do_smartsack = 1;
201SYSCTL_INT(_net_inet_tcp, OID_AUTO, smartsack, CTLFLAG_RW,
202 &tcp_do_smartsack, 0, "Enable Smart SACK Algorithms");
203
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204SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass, CTLFLAG_RW, 0,
205 "TCP Segment Reassembly Queue");
206
207int tcp_reass_maxseg = 0;
208SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RD,
209 &tcp_reass_maxseg, 0,
210 "Global maximum number of TCP Segments in Reassembly Queue");
211
212int tcp_reass_qsize = 0;
213SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, cursegments, CTLFLAG_RD,
214 &tcp_reass_qsize, 0,
215 "Global number of TCP Segments currently in Reassembly Queue");
216
217static int tcp_reass_overflows = 0;
218SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, overflows, CTLFLAG_RD,
219 &tcp_reass_overflows, 0,
220 "Global number of TCP Segment Reassembly Queue Overflows");
221
95b22adf 222static void tcp_dooptions(struct tcpopt *, u_char *, int, boolean_t);
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223static void tcp_pulloutofband(struct socket *,
224 struct tcphdr *, struct mbuf *, int);
225static int tcp_reass(struct tcpcb *, struct tcphdr *, int *,
226 struct mbuf *);
227static void tcp_xmit_timer(struct tcpcb *, int);
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228static void tcp_newreno_partial_ack(struct tcpcb *, struct tcphdr *, int);
229static void tcp_sack_rexmt(struct tcpcb *, struct tcphdr *);
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230
231/* Neighbor Discovery, Neighbor Unreachability Detection Upper layer hint. */
232#ifdef INET6
233#define ND6_HINT(tp) \
234do { \
235 if ((tp) && (tp)->t_inpcb && \
61896e3c 236 ((tp)->t_inpcb->inp_vflag & INP_IPV6) && \
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237 (tp)->t_inpcb->in6p_route.ro_rt) \
238 nd6_nud_hint((tp)->t_inpcb->in6p_route.ro_rt, NULL, 0); \
239} while (0)
240#else
241#define ND6_HINT(tp)
242#endif
243
244/*
245 * Indicate whether this ack should be delayed. We can delay the ack if
246 * - delayed acks are enabled and
247 * - there is no delayed ack timer in progress and
248 * - our last ack wasn't a 0-sized window. We never want to delay
249 * the ack that opens up a 0-sized window.
250 */
251#define DELAY_ACK(tp) \
252 (tcp_delack_enabled && !callout_pending(tp->tt_delack) && \
61896e3c 253 !(tp->t_flags & TF_RXWIN0SENT))
984263bc 254
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255#define acceptable_window_update(tp, th, tiwin) \
256 (SEQ_LT(tp->snd_wl1, th->th_seq) || \
257 (tp->snd_wl1 == th->th_seq && \
258 (SEQ_LT(tp->snd_wl2, th->th_ack) || \
259 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))
260
984263bc 261static int
95b22adf 262tcp_reass(struct tcpcb *tp, struct tcphdr *th, int *tlenp, struct mbuf *m)
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263{
264 struct tseg_qent *q;
265 struct tseg_qent *p = NULL;
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266 struct tseg_qent *te;
267 struct socket *so = tp->t_inpcb->inp_socket;
268 int flags;
269
270 /*
61896e3c 271 * Call with th == NULL after become established to
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272 * force pre-ESTABLISHED data up to user socket.
273 */
61896e3c 274 if (th == NULL)
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275 goto present;
276
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277 /*
278 * Limit the number of segments in the reassembly queue to prevent
279 * holding on to too many segments (and thus running out of mbufs).
280 * Make sure to let the missing segment through which caused this
281 * queue. Always keep one global queue entry spare to be able to
282 * process the missing segment.
283 */
284 if (th->th_seq != tp->rcv_nxt &&
285 tcp_reass_qsize + 1 >= tcp_reass_maxseg) {
286 tcp_reass_overflows++;
287 tcpstat.tcps_rcvmemdrop++;
288 m_freem(m);
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289 /* no SACK block to report */
290 tp->reportblk.rblk_start = tp->reportblk.rblk_end;
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291 return (0);
292 }
293
ba4e3dbe 294 /* Allocate a new queue entry. */
984263bc 295 MALLOC(te, struct tseg_qent *, sizeof(struct tseg_qent), M_TSEGQ,
ba4e3dbe 296 M_INTWAIT | M_NULLOK);
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297 if (te == NULL) {
298 tcpstat.tcps_rcvmemdrop++;
299 m_freem(m);
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300 /* no SACK block to report */
301 tp->reportblk.rblk_start = tp->reportblk.rblk_end;
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302 return (0);
303 }
3edf7c37 304 tcp_reass_qsize++;
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305
306 /*
307 * Find a segment which begins after this one does.
308 */
309 LIST_FOREACH(q, &tp->t_segq, tqe_q) {
310 if (SEQ_GT(q->tqe_th->th_seq, th->th_seq))
311 break;
312 p = q;
313 }
314
315 /*
316 * If there is a preceding segment, it may provide some of
317 * our data already. If so, drop the data from the incoming
318 * segment. If it provides all of our data, drop us.
319 */
320 if (p != NULL) {
2256ba69 321 int i;
91489f6b 322
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323 /* conversion to int (in i) handles seq wraparound */
324 i = p->tqe_th->th_seq + p->tqe_len - th->th_seq;
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325 if (i > 0) { /* overlaps preceding segment */
326 tp->t_flags |= (TF_DUPSEG | TF_ENCLOSESEG);
327 /* enclosing block starts w/ preceding segment */
328 tp->encloseblk.rblk_start = p->tqe_th->th_seq;
984263bc 329 if (i >= *tlenp) {
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330 /* preceding encloses incoming segment */
331 tp->encloseblk.rblk_end = p->tqe_th->th_seq +
332 p->tqe_len;
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333 tcpstat.tcps_rcvduppack++;
334 tcpstat.tcps_rcvdupbyte += *tlenp;
335 m_freem(m);
336 free(te, M_TSEGQ);
3edf7c37 337 tcp_reass_qsize--;
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338 /*
339 * Try to present any queued data
340 * at the left window edge to the user.
341 * This is needed after the 3-WHS
342 * completes.
343 */
344 goto present; /* ??? */
345 }
346 m_adj(m, i);
347 *tlenp -= i;
348 th->th_seq += i;
91489f6b
JH
349 /* incoming segment end is enclosing block end */
350 tp->encloseblk.rblk_end = th->th_seq + *tlenp +
351 ((th->th_flags & TH_FIN) != 0);
352 /* trim end of reported D-SACK block */
353 tp->reportblk.rblk_end = th->th_seq;
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354 }
355 }
356 tcpstat.tcps_rcvoopack++;
357 tcpstat.tcps_rcvoobyte += *tlenp;
358
359 /*
360 * While we overlap succeeding segments trim them or,
361 * if they are completely covered, dequeue them.
362 */
363 while (q) {
2256ba69 364 int i = (th->th_seq + *tlenp) - q->tqe_th->th_seq;
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365 tcp_seq qend = q->tqe_th->th_seq + q->tqe_len;
366 struct tseg_qent *nq;
367
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368 if (i <= 0)
369 break;
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JH
370 if (!(tp->t_flags & TF_DUPSEG)) { /* first time through */
371 tp->t_flags |= (TF_DUPSEG | TF_ENCLOSESEG);
372 tp->encloseblk = tp->reportblk;
373 /* report trailing duplicate D-SACK segment */
374 tp->reportblk.rblk_start = q->tqe_th->th_seq;
375 }
376 if ((tp->t_flags & TF_ENCLOSESEG) &&
377 SEQ_GT(qend, tp->encloseblk.rblk_end)) {
378 /* extend enclosing block if one exists */
379 tp->encloseblk.rblk_end = qend;
380 }
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381 if (i < q->tqe_len) {
382 q->tqe_th->th_seq += i;
383 q->tqe_len -= i;
384 m_adj(q->tqe_m, i);
385 break;
386 }
387
388 nq = LIST_NEXT(q, tqe_q);
389 LIST_REMOVE(q, tqe_q);
390 m_freem(q->tqe_m);
391 free(q, M_TSEGQ);
3edf7c37 392 tcp_reass_qsize--;
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393 q = nq;
394 }
395
396 /* Insert the new segment queue entry into place. */
397 te->tqe_m = m;
398 te->tqe_th = th;
399 te->tqe_len = *tlenp;
400
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JH
401 /* check if can coalesce with following segment */
402 if (q != NULL && (th->th_seq + *tlenp == q->tqe_th->th_seq)) {
403 tcp_seq tend = te->tqe_th->th_seq + te->tqe_len;
404
405 te->tqe_len += q->tqe_len;
a174690a 406 if (q->tqe_th->th_flags & TH_FIN)
f16f8cc3 407 te->tqe_th->th_flags |= TH_FIN;
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JH
408 m_cat(te->tqe_m, q->tqe_m);
409 tp->encloseblk.rblk_end = tend;
410 /*
411 * When not reporting a duplicate segment, use
412 * the larger enclosing block as the SACK block.
413 */
414 if (!(tp->t_flags & TF_DUPSEG))
415 tp->reportblk.rblk_end = tend;
416 LIST_REMOVE(q, tqe_q);
417 free(q, M_TSEGQ);
418 tcp_reass_qsize--;
419 }
420
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421 if (p == NULL) {
422 LIST_INSERT_HEAD(&tp->t_segq, te, tqe_q);
423 } else {
91489f6b
JH
424 /* check if can coalesce with preceding segment */
425 if (p->tqe_th->th_seq + p->tqe_len == th->th_seq) {
a174690a
JH
426 p->tqe_len += te->tqe_len;
427 m_cat(p->tqe_m, te->tqe_m);
91489f6b
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428 tp->encloseblk.rblk_start = p->tqe_th->th_seq;
429 /*
430 * When not reporting a duplicate segment, use
431 * the larger enclosing block as the SACK block.
432 */
433 if (!(tp->t_flags & TF_DUPSEG))
434 tp->reportblk.rblk_start = p->tqe_th->th_seq;
a174690a
JH
435 free(te, M_TSEGQ);
436 tcp_reass_qsize--;
91489f6b
JH
437 } else
438 LIST_INSERT_AFTER(p, te, tqe_q);
984263bc
MD
439 }
440
441present:
442 /*
443 * Present data to user, advancing rcv_nxt through
444 * completed sequence space.
445 */
446 if (!TCPS_HAVEESTABLISHED(tp->t_state))
447 return (0);
448 q = LIST_FIRST(&tp->t_segq);
61896e3c 449 if (q == NULL || q->tqe_th->th_seq != tp->rcv_nxt)
984263bc 450 return (0);
91489f6b
JH
451 tp->rcv_nxt += q->tqe_len;
452 if (!(tp->t_flags & TF_DUPSEG)) {
453 /* no SACK block to report since ACK advanced */
454 tp->reportblk.rblk_start = tp->reportblk.rblk_end;
455 }
456 /* no enclosing block to report since ACK advanced */
457 tp->t_flags &= ~TF_ENCLOSESEG;
458 flags = q->tqe_th->th_flags & TH_FIN;
459 LIST_REMOVE(q, tqe_q);
460 KASSERT(LIST_EMPTY(&tp->t_segq) ||
461 LIST_FIRST(&tp->t_segq)->tqe_th->th_seq != tp->rcv_nxt,
462 ("segment not coalesced"));
463 if (so->so_state & SS_CANTRCVMORE)
464 m_freem(q->tqe_m);
465 else
507106e0 466 sbappendstream(&so->so_rcv, q->tqe_m);
91489f6b
JH
467 free(q, M_TSEGQ);
468 tcp_reass_qsize--;
984263bc
MD
469 ND6_HINT(tp);
470 sorwakeup(so);
471 return (flags);
472}
473
474/*
475 * TCP input routine, follows pages 65-76 of the
476 * protocol specification dated September, 1981 very closely.
477 */
478#ifdef INET6
479int
95b22adf 480tcp6_input(struct mbuf **mp, int *offp, int proto)
984263bc 481{
2256ba69 482 struct mbuf *m = *mp;
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MD
483 struct in6_ifaddr *ia6;
484
485 IP6_EXTHDR_CHECK(m, *offp, sizeof(struct tcphdr), IPPROTO_DONE);
486
487 /*
488 * draft-itojun-ipv6-tcp-to-anycast
489 * better place to put this in?
490 */
491 ia6 = ip6_getdstifaddr(m);
d24ce1dc 492 if (ia6 && (ia6->ia6_flags & IN6_IFF_ANYCAST)) {
984263bc
MD
493 struct ip6_hdr *ip6;
494
495 ip6 = mtod(m, struct ip6_hdr *);
496 icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR,
497 (caddr_t)&ip6->ip6_dst - (caddr_t)ip6);
d24ce1dc 498 return (IPPROTO_DONE);
984263bc
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499 }
500
501 tcp_input(m, *offp, proto);
d24ce1dc 502 return (IPPROTO_DONE);
984263bc
MD
503}
504#endif
505
506void
a00138cb 507tcp_input(struct mbuf *m, ...)
984263bc 508{
a00138cb
JS
509 __va_list ap;
510 int off0, proto;
2256ba69
RG
511 struct tcphdr *th;
512 struct ip *ip = NULL;
513 struct ipovly *ipov;
514 struct inpcb *inp = NULL;
984263bc
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515 u_char *optp = NULL;
516 int optlen = 0;
517 int len, tlen, off;
518 int drop_hdrlen;
2256ba69
RG
519 struct tcpcb *tp = NULL;
520 int thflags;
984263bc 521 struct socket *so = 0;
61896e3c
JH
522 int todrop, acked;
523 boolean_t ourfinisacked, needoutput = FALSE;
984263bc 524 u_long tiwin;
61896e3c 525 int recvwin;
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MD
526 struct tcpopt to; /* options in this segment */
527 struct rmxp_tao *taop; /* pointer to our TAO cache entry */
528 struct rmxp_tao tao_noncached; /* in case there's no cached entry */
529 struct sockaddr_in *next_hop = NULL;
530 int rstreason; /* For badport_bandlim accounting purposes */
d371a63a 531 int cpu;
984263bc
MD
532 struct ip6_hdr *ip6 = NULL;
533#ifdef INET6
d24ce1dc 534 boolean_t isipv6;
984263bc 535#else
d24ce1dc 536 const boolean_t isipv6 = FALSE;
984263bc
MD
537#endif
538#ifdef TCPDEBUG
539 short ostate = 0;
540#endif
541
a00138cb
JS
542 __va_start(ap, m);
543 off0 = __va_arg(ap, int);
544 proto = __va_arg(ap, int);
545 __va_end(ap);
546
d24ce1dc
JH
547 tcpstat.tcps_rcvtotal++;
548
549 /* Grab info from and strip MT_TAG mbufs prepended to the chain. */
550 while (m->m_type == MT_TAG) {
984263bc
MD
551 if (m->_m_tag_id == PACKET_TAG_IPFORWARD)
552 next_hop = (struct sockaddr_in *)m->m_hdr.mh_data;
d24ce1dc 553 m = m->m_next;
984263bc 554 }
d24ce1dc 555
984263bc 556#ifdef INET6
d24ce1dc 557 isipv6 = (mtod(m, struct ip *)->ip_v == 6) ? TRUE : FALSE;
984263bc 558#endif
984263bc
MD
559
560 if (isipv6) {
561 /* IP6_EXTHDR_CHECK() is already done at tcp6_input() */
562 ip6 = mtod(m, struct ip6_hdr *);
563 tlen = sizeof(*ip6) + ntohs(ip6->ip6_plen) - off0;
564 if (in6_cksum(m, IPPROTO_TCP, off0, tlen)) {
565 tcpstat.tcps_rcvbadsum++;
566 goto drop;
567 }
568 th = (struct tcphdr *)((caddr_t)ip6 + off0);
569
570 /*
571 * Be proactive about unspecified IPv6 address in source.
572 * As we use all-zero to indicate unbounded/unconnected pcb,
573 * unspecified IPv6 address can be used to confuse us.
574 *
575 * Note that packets with unspecified IPv6 destination is
576 * already dropped in ip6_input.
577 */
578 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) {
579 /* XXX stat */
580 goto drop;
581 }
582 } else {
583 /*
584 * Get IP and TCP header together in first mbuf.
585 * Note: IP leaves IP header in first mbuf.
586 */
587 if (off0 > sizeof(struct ip)) {
bddf0751 588 ip_stripoptions(m);
984263bc
MD
589 off0 = sizeof(struct ip);
590 }
55d829f8
JH
591 /* already checked and pulled up in ip_demux() */
592 KASSERT(m->m_len >= sizeof(struct tcpiphdr),
61896e3c 593 ("TCP header not in one mbuf: m->m_len %d", m->m_len));
984263bc
MD
594 ip = mtod(m, struct ip *);
595 ipov = (struct ipovly *)ip;
596 th = (struct tcphdr *)((caddr_t)ip + off0);
597 tlen = ip->ip_len;
598
599 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) {
600 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR)
601 th->th_sum = m->m_pkthdr.csum_data;
602 else
603 th->th_sum = in_pseudo(ip->ip_src.s_addr,
604 ip->ip_dst.s_addr,
605 htonl(m->m_pkthdr.csum_data +
606 ip->ip_len +
607 IPPROTO_TCP));
608 th->th_sum ^= 0xffff;
609 } else {
610 /*
611 * Checksum extended TCP header and data.
612 */
613 len = sizeof(struct ip) + tlen;
614 bzero(ipov->ih_x1, sizeof(ipov->ih_x1));
615 ipov->ih_len = (u_short)tlen;
616 ipov->ih_len = htons(ipov->ih_len);
617 th->th_sum = in_cksum(m, len);
618 }
619 if (th->th_sum) {
620 tcpstat.tcps_rcvbadsum++;
621 goto drop;
622 }
623#ifdef INET6
624 /* Re-initialization for later version check */
625 ip->ip_v = IPVERSION;
626#endif
627 }
628
629 /*
630 * Check that TCP offset makes sense,
631 * pull out TCP options and adjust length. XXX
632 */
633 off = th->th_off << 2;
55d829f8
JH
634 /* already checked and pulled up in ip_demux() */
635 KASSERT(off >= sizeof(struct tcphdr) && off <= tlen,
61896e3c 636 ("bad TCP data offset %d (tlen %d)", off, tlen));
984263bc
MD
637 tlen -= off; /* tlen is used instead of ti->ti_len */
638 if (off > sizeof(struct tcphdr)) {
639 if (isipv6) {
640 IP6_EXTHDR_CHECK(m, off0, off, );
641 ip6 = mtod(m, struct ip6_hdr *);
642 th = (struct tcphdr *)((caddr_t)ip6 + off0);
643 } else {
55d829f8
JH
644 /* already pulled up in ip_demux() */
645 KASSERT(m->m_len >= sizeof(struct ip) + off,
61896e3c
JH
646 ("TCP header and options not in one mbuf: "
647 "m_len %d, off %d", m->m_len, off));
984263bc
MD
648 }
649 optlen = off - sizeof(struct tcphdr);
650 optp = (u_char *)(th + 1);
651 }
652 thflags = th->th_flags;
653
654#ifdef TCP_DROP_SYNFIN
655 /*
656 * If the drop_synfin option is enabled, drop all packets with
657 * both the SYN and FIN bits set. This prevents e.g. nmap from
658 * identifying the TCP/IP stack.
659 *
660 * This is a violation of the TCP specification.
661 */
61896e3c 662 if (drop_synfin && (thflags & (TH_SYN | TH_FIN)) == (TH_SYN | TH_FIN))
984263bc
MD
663 goto drop;
664#endif
665
666 /*
667 * Convert TCP protocol specific fields to host format.
668 */
669 th->th_seq = ntohl(th->th_seq);
670 th->th_ack = ntohl(th->th_ack);
671 th->th_win = ntohs(th->th_win);
672 th->th_urp = ntohs(th->th_urp);
673
674 /*
d24ce1dc 675 * Delay dropping TCP, IP headers, IPv6 ext headers, and TCP options,
984263bc
MD
676 * until after ip6_savecontrol() is called and before other functions
677 * which don't want those proto headers.
678 * Because ip6_savecontrol() is going to parse the mbuf to
679 * search for data to be passed up to user-land, it wants mbuf
680 * parameters to be unchanged.
681 * XXX: the call of ip6_savecontrol() has been obsoleted based on
682 * latest version of the advanced API (20020110).
683 */
684 drop_hdrlen = off0 + off;
685
686 /*
687 * Locate pcb for segment.
688 */
689findpcb:
690 /* IPFIREWALL_FORWARD section */
d24ce1dc 691 if (next_hop != NULL && !isipv6) { /* IPv6 support is not there yet */
984263bc
MD
692 /*
693 * Transparently forwarded. Pretend to be the destination.
d24ce1dc 694 * already got one like this?
984263bc 695 */
6ca1a1cd 696 cpu = mycpu->gd_cpuid;
6ca1a1cd 697 inp = in_pcblookup_hash(&tcbinfo[cpu],
d371a63a 698 ip->ip_src, th->th_sport,
984263bc
MD
699 ip->ip_dst, th->th_dport,
700 0, m->m_pkthdr.rcvif);
701 if (!inp) {
83be63fe
JH
702 /*
703 * It's new. Try to find the ambushing socket.
704 */
705
706 /*
707 * The rest of the ipfw code stores the port in
708 * host order. XXX
709 * (The IP address is still in network order.)
710 */
711 in_port_t dport = next_hop->sin_port ?
712 htons(next_hop->sin_port) :
713 th->th_dport;
714
d371a63a 715 cpu = tcp_addrcpu(ip->ip_src.s_addr, th->th_sport,
83be63fe 716 next_hop->sin_addr.s_addr, dport);
d371a63a 717 inp = in_pcblookup_hash(&tcbinfo[cpu],
984263bc 718 ip->ip_src, th->th_sport,
83be63fe 719 next_hop->sin_addr, dport,
984263bc
MD
720 1, m->m_pkthdr.rcvif);
721 }
722 } else {
6ca1a1cd 723 if (isipv6) {
d371a63a 724 inp = in6_pcblookup_hash(&tcbinfo[0],
984263bc
MD
725 &ip6->ip6_src, th->th_sport,
726 &ip6->ip6_dst, th->th_dport,
727 1, m->m_pkthdr.rcvif);
6ca1a1cd 728 } else {
6ca1a1cd 729 cpu = mycpu->gd_cpuid;
6ca1a1cd 730 inp = in_pcblookup_hash(&tcbinfo[cpu],
984263bc
MD
731 ip->ip_src, th->th_sport,
732 ip->ip_dst, th->th_dport,
733 1, m->m_pkthdr.rcvif);
6ca1a1cd 734 }
984263bc 735 }
984263bc
MD
736
737 /*
738 * If the state is CLOSED (i.e., TCB does not exist) then
739 * all data in the incoming segment is discarded.
740 * If the TCB exists but is in CLOSED state, it is embryonic,
741 * but should either do a listen or a connect soon.
742 */
743 if (inp == NULL) {
744 if (log_in_vain) {
745#ifdef INET6
746 char dbuf[INET6_ADDRSTRLEN+2], sbuf[INET6_ADDRSTRLEN+2];
747#else
d24ce1dc 748 char dbuf[4 * sizeof "123"], sbuf[4 * sizeof "123"];
984263bc
MD
749#endif
750 if (isipv6) {
751 strcpy(dbuf, "[");
984263bc 752 strcat(dbuf, ip6_sprintf(&ip6->ip6_dst));
984263bc 753 strcat(dbuf, "]");
95b22adf
JH
754 strcpy(sbuf, "[");
755 strcat(sbuf, ip6_sprintf(&ip6->ip6_src));
984263bc
MD
756 strcat(sbuf, "]");
757 } else {
758 strcpy(dbuf, inet_ntoa(ip->ip_dst));
759 strcpy(sbuf, inet_ntoa(ip->ip_src));
760 }
761 switch (log_in_vain) {
762 case 1:
61896e3c 763 if (!(thflags & TH_SYN))
984263bc
MD
764 break;
765 case 2:
766 log(LOG_INFO,
767 "Connection attempt to TCP %s:%d "
768 "from %s:%d flags:0x%02x\n",
769 dbuf, ntohs(th->th_dport), sbuf,
770 ntohs(th->th_sport), thflags);
771 break;
772 default:
773 break;
774 }
775 }
d24ce1dc 776 if (blackhole) {
984263bc
MD
777 switch (blackhole) {
778 case 1:
779 if (thflags & TH_SYN)
780 goto drop;
781 break;
782 case 2:
783 goto drop;
784 default:
785 goto drop;
786 }
787 }
788 rstreason = BANDLIM_RST_CLOSEDPORT;
789 goto dropwithreset;
790 }
61896e3c
JH
791
792#ifdef IPSEC
793 if (isipv6) {
794 if (ipsec6_in_reject_so(m, inp->inp_socket)) {
795 ipsec6stat.in_polvio++;
796 goto drop;
797 }
798 } else {
799 if (ipsec4_in_reject_so(m, inp->inp_socket)) {
800 ipsecstat.in_polvio++;
801 goto drop;
802 }
803 }
804#endif
805#ifdef FAST_IPSEC
806 if (isipv6) {
807 if (ipsec6_in_reject(m, inp))
808 goto drop;
809 } else {
810 if (ipsec4_in_reject(m, inp))
811 goto drop;
812 }
813#endif
814
984263bc
MD
815 tp = intotcpcb(inp);
816 if (tp == NULL) {
817 rstreason = BANDLIM_RST_CLOSEDPORT;
818 goto dropwithreset;
819 }
eb594563 820 if (tp->t_state <= TCPS_CLOSED)
984263bc
MD
821 goto drop;
822
823 /* Unscale the window into a 32-bit value. */
95b22adf 824 if (!(thflags & TH_SYN))
984263bc
MD
825 tiwin = th->th_win << tp->snd_scale;
826 else
827 tiwin = th->th_win;
828
829 so = inp->inp_socket;
47654766 830
984263bc 831#ifdef TCPDEBUG
47654766
JH
832 if (so->so_options & SO_DEBUG) {
833 ostate = tp->t_state;
834 if (isipv6)
95b22adf 835 bcopy(ip6, tcp_saveipgen, sizeof(*ip6));
47654766 836 else
95b22adf 837 bcopy(ip, tcp_saveipgen, sizeof(*ip));
47654766
JH
838 tcp_savetcp = *th;
839 }
984263bc 840#endif
47654766 841
95b22adf 842 bzero(&to, sizeof(to));
d24ce1dc 843
47654766
JH
844 if (so->so_options & SO_ACCEPTCONN) {
845 struct in_conninfo inc;
846
984263bc 847#ifdef INET6
d24ce1dc 848 inc.inc_isipv6 = (isipv6 == TRUE);
984263bc
MD
849#endif
850 if (isipv6) {
851 inc.inc6_faddr = ip6->ip6_src;
852 inc.inc6_laddr = ip6->ip6_dst;
853 inc.inc6_route.ro_rt = NULL; /* XXX */
854 } else {
855 inc.inc_faddr = ip->ip_src;
856 inc.inc_laddr = ip->ip_dst;
857 inc.inc_route.ro_rt = NULL; /* XXX */
858 }
859 inc.inc_fport = th->th_sport;
860 inc.inc_lport = th->th_dport;
861
61896e3c
JH
862 /*
863 * If the state is LISTEN then ignore segment if it contains
984263bc
MD
864 * a RST. If the segment contains an ACK then it is bad and
865 * send a RST. If it does not contain a SYN then it is not
866 * interesting; drop it.
867 *
868 * If the state is SYN_RECEIVED (syncache) and seg contains
869 * an ACK, but not for our SYN/ACK, send a RST. If the seg
870 * contains a RST, check the sequence number to see if it
871 * is a valid reset segment.
872 */
61896e3c
JH
873 if ((thflags & (TH_RST | TH_ACK | TH_SYN)) != TH_SYN) {
874 if ((thflags & (TH_RST | TH_ACK | TH_SYN)) == TH_ACK) {
984263bc
MD
875 if (!syncache_expand(&inc, th, &so, m)) {
876 /*
877 * No syncache entry, or ACK was not
878 * for our SYN/ACK. Send a RST.
879 */
880 tcpstat.tcps_badsyn++;
881 rstreason = BANDLIM_RST_OPENPORT;
882 goto dropwithreset;
883 }
884 if (so == NULL)
885 /*
886 * Could not complete 3-way handshake,
887 * connection is being closed down, and
888 * syncache will free mbuf.
889 */
890 return;
891 /*
892 * Socket is created in state SYN_RECEIVED.
893 * Continue processing segment.
894 */
895 inp = sotoinpcb(so);
896 tp = intotcpcb(inp);
897 /*
898 * This is what would have happened in
899 * tcp_output() when the SYN,ACK was sent.
900 */
901 tp->snd_up = tp->snd_una;
902 tp->snd_max = tp->snd_nxt = tp->iss + 1;
903 tp->last_ack_sent = tp->rcv_nxt;
904/*
905 * XXX possible bug - it doesn't appear that tp->snd_wnd is unscaled
906 * until the _second_ ACK is received:
907 * rcv SYN (set wscale opts) --> send SYN/ACK, set snd_wnd = window.
908 * rcv ACK, calculate tiwin --> process SYN_RECEIVED, determine wscale,
61896e3c 909 * move to ESTAB, set snd_wnd to tiwin.
d24ce1dc 910 */
984263bc
MD
911 tp->snd_wnd = tiwin; /* unscaled */
912 goto after_listen;
913 }
914 if (thflags & TH_RST) {
915 syncache_chkrst(&inc, th);
916 goto drop;
917 }
918 if (thflags & TH_ACK) {
919 syncache_badack(&inc);
920 tcpstat.tcps_badsyn++;
921 rstreason = BANDLIM_RST_OPENPORT;
922 goto dropwithreset;
923 }
924 goto drop;
925 }
926
927 /*
61896e3c 928 * Segment's flags are (SYN) or (SYN | FIN).
984263bc
MD
929 */
930#ifdef INET6
931 /*
932 * If deprecated address is forbidden,
933 * we do not accept SYN to deprecated interface
934 * address to prevent any new inbound connection from
935 * getting established.
936 * When we do not accept SYN, we send a TCP RST,
937 * with deprecated source address (instead of dropping
938 * it). We compromise it as it is much better for peer
939 * to send a RST, and RST will be the final packet
940 * for the exchange.
941 *
942 * If we do not forbid deprecated addresses, we accept
943 * the SYN packet. RFC2462 does not suggest dropping
944 * SYN in this case.
945 * If we decipher RFC2462 5.5.4, it says like this:
946 * 1. use of deprecated addr with existing
947 * communication is okay - "SHOULD continue to be
948 * used"
949 * 2. use of it with new communication:
950 * (2a) "SHOULD NOT be used if alternate address
61896e3c 951 * with sufficient scope is available"
984263bc
MD
952 * (2b) nothing mentioned otherwise.
953 * Here we fall into (2b) case as we have no choice in
954 * our source address selection - we must obey the peer.
955 *
956 * The wording in RFC2462 is confusing, and there are
957 * multiple description text for deprecated address
958 * handling - worse, they are not exactly the same.
959 * I believe 5.5.4 is the best one, so we follow 5.5.4.
960 */
961 if (isipv6 && !ip6_use_deprecated) {
962 struct in6_ifaddr *ia6;
963
964 if ((ia6 = ip6_getdstifaddr(m)) &&
965 (ia6->ia6_flags & IN6_IFF_DEPRECATED)) {
966 tp = NULL;
967 rstreason = BANDLIM_RST_OPENPORT;
968 goto dropwithreset;
969 }
970 }
971#endif
972 /*
973 * If it is from this socket, drop it, it must be forged.
974 * Don't bother responding if the destination was a broadcast.
975 */
976 if (th->th_dport == th->th_sport) {
977 if (isipv6) {
978 if (IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst,
979 &ip6->ip6_src))
980 goto drop;
981 } else {
982 if (ip->ip_dst.s_addr == ip->ip_src.s_addr)
983 goto drop;
984 }
985 }
986 /*
987 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN
988 *
989 * Note that it is quite possible to receive unicast
990 * link-layer packets with a broadcast IP address. Use
991 * in_broadcast() to find them.
992 */
61896e3c 993 if (m->m_flags & (M_BCAST | M_MCAST))
984263bc
MD
994 goto drop;
995 if (isipv6) {
996 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
997 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src))
998 goto drop;
999 } else {
1000 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) ||
1001 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
1002 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) ||
1003 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif))
1004 goto drop;
1005 }
1006 /*
1007 * SYN appears to be valid; create compressed TCP state
1008 * for syncache, or perform t/tcp connection.
1009 */
1010 if (so->so_qlen <= so->so_qlimit) {
95b22adf 1011 tcp_dooptions(&to, optp, optlen, TRUE);
984263bc
MD
1012 if (!syncache_add(&inc, &to, th, &so, m))
1013 goto drop;
1014 if (so == NULL)
1015 /*
1016 * Entry added to syncache, mbuf used to
1017 * send SYN,ACK packet.
1018 */
1019 return;
1020 /*
1021 * Segment passed TAO tests.
1022 */
1023 inp = sotoinpcb(so);
1024 tp = intotcpcb(inp);
1025 tp->snd_wnd = tiwin;
1026 tp->t_starttime = ticks;
1027 tp->t_state = TCPS_ESTABLISHED;
1028
1029 /*
1030 * If there is a FIN, or if there is data and the
1031 * connection is local, then delay SYN,ACK(SYN) in
1032 * the hope of piggy-backing it on a response
1033 * segment. Otherwise must send ACK now in case
1034 * the other side is slow starting.
1035 */
1036 if (DELAY_ACK(tp) &&
1037 ((thflags & TH_FIN) ||
1038 (tlen != 0 &&
1039 ((isipv6 && in6_localaddr(&inp->in6p_faddr)) ||
1040 (!isipv6 && in_localaddr(inp->inp_faddr)))))) {
d24ce1dc
JH
1041 callout_reset(tp->tt_delack, tcp_delacktime,
1042 tcp_timer_delack, tp);
984263bc 1043 tp->t_flags |= TF_NEEDSYN;
d24ce1dc 1044 } else
984263bc
MD
1045 tp->t_flags |= (TF_ACKNOW | TF_NEEDSYN);
1046
1047 tcpstat.tcps_connects++;
1048 soisconnected(so);
1049 goto trimthenstep6;
1050 }
1051 goto drop;
1052 }
1053after_listen:
1054
984263bc 1055 /* should not happen - syncache should pick up these connections */
61896e3c 1056 KASSERT(tp->t_state != TCPS_LISTEN, ("tcp_input: TCPS_LISTEN state"));
984263bc
MD
1057
1058 /*
1059 * Segment received on connection.
1060 * Reset idle time and keep-alive timer.
1061 */
1062 tp->t_rcvtime = ticks;
1063 if (TCPS_HAVEESTABLISHED(tp->t_state))
1064 callout_reset(tp->tt_keep, tcp_keepidle, tcp_timer_keep, tp);
1065
1066 /*
1067 * Process options.
1068 * XXX this is tradtitional behavior, may need to be cleaned up.
1069 */
95b22adf 1070 tcp_dooptions(&to, optp, optlen, (thflags & TH_SYN) != 0);
984263bc
MD
1071 if (thflags & TH_SYN) {
1072 if (to.to_flags & TOF_SCALE) {
1073 tp->t_flags |= TF_RCVD_SCALE;
1074 tp->requested_s_scale = to.to_requested_s_scale;
1075 }
1076 if (to.to_flags & TOF_TS) {
1077 tp->t_flags |= TF_RCVD_TSTMP;
1078 tp->ts_recent = to.to_tsval;
1079 tp->ts_recent_age = ticks;
1080 }
61896e3c 1081 if (to.to_flags & (TOF_CC | TOF_CCNEW))
984263bc
MD
1082 tp->t_flags |= TF_RCVD_CC;
1083 if (to.to_flags & TOF_MSS)
1084 tcp_mss(tp, to.to_mss);
91489f6b
JH
1085 /*
1086 * Only set the TF_SACK_PERMITTED per-connection flag
1087 * if we got a SACK_PERMITTED option from the other side
1088 * and the global tcp_do_sack variable is true.
1089 */
1090 if (tcp_do_sack && (to.to_flags & TOF_SACK_PERMITTED))
1091 tp->t_flags |= TF_SACK_PERMITTED;
984263bc
MD
1092 }
1093
1094 /*
1095 * Header prediction: check for the two common cases
1096 * of a uni-directional data xfer. If the packet has
1097 * no control flags, is in-sequence, the window didn't
1098 * change and we're not retransmitting, it's a
1099 * candidate. If the length is zero and the ack moved
1100 * forward, we're the sender side of the xfer. Just
1101 * free the data acked & wake any higher level process
1102 * that was blocked waiting for space. If the length
1103 * is non-zero and the ack didn't move, we're the
1104 * receiver side. If we're getting packets in-order
1105 * (the reassembly queue is empty), add the data to
1106 * the socket buffer and note that we need a delayed ack.
1107 * Make sure that the hidden state-flags are also off.
1108 * Since we check for TCPS_ESTABLISHED above, it can only
1109 * be TH_NEEDSYN.
1110 */
1111 if (tp->t_state == TCPS_ESTABLISHED &&
1112 (thflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK &&
61896e3c
JH
1113 !(tp->t_flags & (TF_NEEDSYN | TF_NEEDFIN)) &&
1114 (!(to.to_flags & TOF_TS) ||
984263bc
MD
1115 TSTMP_GEQ(to.to_tsval, tp->ts_recent)) &&
1116 /*
1117 * Using the CC option is compulsory if once started:
1118 * the segment is OK if no T/TCP was negotiated or
1119 * if the segment has a CC option equal to CCrecv
1120 */
1121 ((tp->t_flags & (TF_REQ_CC|TF_RCVD_CC)) != (TF_REQ_CC|TF_RCVD_CC) ||
61896e3c 1122 ((to.to_flags & TOF_CC) && to.to_cc == tp->cc_recv)) &&
984263bc 1123 th->th_seq == tp->rcv_nxt &&
984263bc
MD
1124 tp->snd_nxt == tp->snd_max) {
1125
1126 /*
1127 * If last ACK falls within this segment's sequence numbers,
1128 * record the timestamp.
1129 * NOTE that the test is modified according to the latest
1130 * proposal of the tcplw@cray.com list (Braden 1993/04/26).
1131 */
61896e3c 1132 if ((to.to_flags & TOF_TS) &&
984263bc
MD
1133 SEQ_LEQ(th->th_seq, tp->last_ack_sent)) {
1134 tp->ts_recent_age = ticks;
1135 tp->ts_recent = to.to_tsval;
1136 }
1137
1138 if (tlen == 0) {
1139 if (SEQ_GT(th->th_ack, tp->snd_una) &&
1140 SEQ_LEQ(th->th_ack, tp->snd_max) &&
1141 tp->snd_cwnd >= tp->snd_wnd &&
95b22adf 1142 !IN_FASTRECOVERY(tp)) {
984263bc
MD
1143 /*
1144 * this is a pure ack for outstanding data.
1145 */
1146 ++tcpstat.tcps_predack;
1147 /*
1148 * "bad retransmit" recovery
bfdb979e
JH
1149 *
1150 * If Eifel detection applies, then
1151 * it is deterministic, so use it
1152 * unconditionally over the old heuristic.
1153 * Otherwise, fall back to the old heuristic.
984263bc 1154 */
bfdb979e
JH
1155 if (tcp_do_eifel_detect &&
1156 (to.to_flags & TOF_TS) && to.to_tsecr &&
1157 (tp->t_flags & TF_FIRSTACCACK)) {
1158 /* Eifel detection applicable. */
1159 if (to.to_tsecr < tp->t_rexmtTS) {
1160 tcp_revert_congestion_state(tp);
1161 ++tcpstat.tcps_eifeldetected;
1162 }
1163 } else if (tp->t_rxtshift == 1 &&
1164 ticks < tp->t_badrxtwin) {
1165 tcp_revert_congestion_state(tp);
1166 ++tcpstat.tcps_rttdetected;
984263bc 1167 }
8819433a
JH
1168 tp->t_flags &= ~(TF_FIRSTACCACK |
1169 TF_FASTREXMT | TF_EARLYREXMT);
984263bc
MD
1170 /*
1171 * Recalculate the retransmit timer / rtt.
1172 *
d24ce1dc 1173 * Some machines (certain windows boxes)
984263bc
MD
1174 * send broken timestamp replies during the
1175 * SYN+ACK phase, ignore timestamps of 0.
1176 */
95b22adf 1177 if ((to.to_flags & TOF_TS) && to.to_tsecr) {
984263bc 1178 tcp_xmit_timer(tp,
95b22adf 1179 ticks - to.to_tsecr + 1);
984263bc 1180 } else if (tp->t_rtttime &&
95b22adf 1181 SEQ_GT(th->th_ack, tp->t_rtseq)) {
984263bc
MD
1182 tcp_xmit_timer(tp,
1183 ticks - tp->t_rtttime);
1184 }
1185 tcp_xmit_bandwidth_limit(tp, th->th_ack);
1186 acked = th->th_ack - tp->snd_una;
1187 tcpstat.tcps_rcvackpack++;
1188 tcpstat.tcps_rcvackbyte += acked;
1189 sbdrop(&so->so_snd, acked);
cfb3f3f4 1190 tp->snd_recover = th->th_ack - 1;
9845754e 1191 tp->snd_una = th->th_ack;
984263bc 1192 tp->t_dupacks = 0;
df9d7670
JH
1193 /*
1194 * Update window information.
1195 */
1196 if (tiwin != tp->snd_wnd &&
1197 acceptable_window_update(tp, th, tiwin)) {
1198 /* keep track of pure window updates */
1199 if (tp->snd_wl2 == th->th_ack &&
1200 tiwin > tp->snd_wnd)
1201 tcpstat.tcps_rcvwinupd++;
1202 tp->snd_wnd = tiwin;
1203 tp->snd_wl1 = th->th_seq;
1204 tp->snd_wl2 = th->th_ack;
1205 if (tp->snd_wnd > tp->max_sndwnd)
1206 tp->max_sndwnd = tp->snd_wnd;
1207 }
984263bc
MD
1208 m_freem(m);
1209 ND6_HINT(tp); /* some progress has been done */
984263bc
MD
1210 /*
1211 * If all outstanding data are acked, stop
1212 * retransmit timer, otherwise restart timer
1213 * using current (possibly backed-off) value.
1214 * If process is waiting for space,
1215 * wakeup/selwakeup/signal. If data
1216 * are ready to send, let tcp_output
1217 * decide between more output or persist.
1218 */
1219 if (tp->snd_una == tp->snd_max)
1220 callout_stop(tp->tt_rexmt);
1221 else if (!callout_active(tp->tt_persist))
d24ce1dc 1222 callout_reset(tp->tt_rexmt,
984263bc
MD
1223 tp->t_rxtcur,
1224 tcp_timer_rexmt, tp);
1225
1226 sowwakeup(so);
1227 if (so->so_snd.sb_cc)
1228 (void) tcp_output(tp);
1229 return;
1230 }
df9d7670
JH
1231 } else if (tiwin == tp->snd_wnd &&
1232 th->th_ack == tp->snd_una &&
984263bc
MD
1233 LIST_EMPTY(&tp->t_segq) &&
1234 tlen <= sbspace(&so->so_rcv)) {
1235 /*
1236 * this is a pure, in-sequence data packet
1237 * with nothing on the reassembly queue and
1238 * we have enough buffer space to take it.
1239 */
1240 ++tcpstat.tcps_preddat;
1241 tp->rcv_nxt += tlen;
1242 tcpstat.tcps_rcvpack++;
1243 tcpstat.tcps_rcvbyte += tlen;
1244 ND6_HINT(tp); /* some progress has been done */
1245 /*
1246 * Add data to socket buffer.
1247 */
1248 if (so->so_state & SS_CANTRCVMORE) {
1249 m_freem(m);
1250 } else {
09cf73e0 1251 m_adj(m, drop_hdrlen); /* delayed header drop */
507106e0 1252 sbappendstream(&so->so_rcv, m);
984263bc
MD
1253 }
1254 sorwakeup(so);
2b1ce38a
MD
1255
1256 /*
1257 * This code is responsible for most of the ACKs
1258 * the TCP stack sends back after receiving a data
1259 * packet. Note that the DELAY_ACK check fails if
1260 * the delack timer is already running, which results
1261 * in an ack being sent every other packet (which is
1262 * what we want).
1263 */
984263bc 1264 if (DELAY_ACK(tp)) {
61896e3c
JH
1265 callout_reset(tp->tt_delack, tcp_delacktime,
1266 tcp_timer_delack, tp);
984263bc
MD
1267 } else {
1268 tp->t_flags |= TF_ACKNOW;
61896e3c 1269 if (!(tp->t_flags & TF_ONOUTPUTQ)) {
2b1ce38a
MD
1270 tp->t_flags |= TF_ONOUTPUTQ;
1271 tp->tt_cpu = mycpu->gd_cpuid;
1272 TAILQ_INSERT_TAIL(
1273 &tcpcbackq[tp->tt_cpu],
1274 tp, t_outputq);
1275 }
984263bc
MD
1276 }
1277 return;
1278 }
1279 }
1280
1281 /*
1282 * Calculate amount of space in receive window,
1283 * and then do TCP input processing.
1284 * Receive window is amount of space in rcv queue,
1285 * but not less than advertised window.
1286 */
61896e3c
JH
1287 recvwin = sbspace(&so->so_rcv);
1288 if (recvwin < 0)
1289 recvwin = 0;
1290 tp->rcv_wnd = imax(recvwin, (int)(tp->rcv_adv - tp->rcv_nxt));
984263bc
MD
1291
1292 switch (tp->t_state) {
984263bc
MD
1293 /*
1294 * If the state is SYN_RECEIVED:
1295 * if seg contains an ACK, but not for our SYN/ACK, send a RST.
1296 */
1297 case TCPS_SYN_RECEIVED:
1298 if ((thflags & TH_ACK) &&
1299 (SEQ_LEQ(th->th_ack, tp->snd_una) ||
1300 SEQ_GT(th->th_ack, tp->snd_max))) {
1301 rstreason = BANDLIM_RST_OPENPORT;
1302 goto dropwithreset;
1303 }
1304 break;
1305
1306 /*
1307 * If the state is SYN_SENT:
1308 * if seg contains an ACK, but not for our SYN, drop the input.
1309 * if seg contains a RST, then drop the connection.
1310 * if seg does not contain SYN, then drop it.
1311 * Otherwise this is an acceptable SYN segment
1312 * initialize tp->rcv_nxt and tp->irs
1313 * if seg contains ack then advance tp->snd_una
1314 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state
1315 * arrange for segment to be acked (eventually)
1316 * continue processing rest of data/controls, beginning with URG
1317 */
1318 case TCPS_SYN_SENT:
1319 if ((taop = tcp_gettaocache(&inp->inp_inc)) == NULL) {
1320 taop = &tao_noncached;
1321 bzero(taop, sizeof(*taop));
1322 }
1323
1324 if ((thflags & TH_ACK) &&
1325 (SEQ_LEQ(th->th_ack, tp->iss) ||
1326 SEQ_GT(th->th_ack, tp->snd_max))) {
1327 /*
1328 * If we have a cached CCsent for the remote host,
1329 * hence we haven't just crashed and restarted,
1330 * do not send a RST. This may be a retransmission
1331 * from the other side after our earlier ACK was lost.
1332 * Our new SYN, when it arrives, will serve as the
1333 * needed ACK.
1334 */
1335 if (taop->tao_ccsent != 0)
1336 goto drop;
1337 else {
1338 rstreason = BANDLIM_UNLIMITED;
1339 goto dropwithreset;
1340 }
1341 }
1342 if (thflags & TH_RST) {
1343 if (thflags & TH_ACK)
1344 tp = tcp_drop(tp, ECONNREFUSED);
1345 goto drop;
1346 }
61896e3c 1347 if (!(thflags & TH_SYN))
984263bc
MD
1348 goto drop;
1349 tp->snd_wnd = th->th_win; /* initial send window */
1350 tp->cc_recv = to.to_cc; /* foreign CC */
1351
1352 tp->irs = th->th_seq;
1353 tcp_rcvseqinit(tp);
1354 if (thflags & TH_ACK) {
1355 /*
1356 * Our SYN was acked. If segment contains CC.ECHO
1357 * option, check it to make sure this segment really
1358 * matches our SYN. If not, just drop it as old
1359 * duplicate, but send an RST if we're still playing
1360 * by the old rules. If no CC.ECHO option, make sure
1361 * we don't get fooled into using T/TCP.
1362 */
1363 if (to.to_flags & TOF_CCECHO) {
1364 if (tp->cc_send != to.to_ccecho) {
1365 if (taop->tao_ccsent != 0)
1366 goto drop;
1367 else {
1368 rstreason = BANDLIM_UNLIMITED;
1369 goto dropwithreset;
1370 }
1371 }
1372 } else
1373 tp->t_flags &= ~TF_RCVD_CC;
1374 tcpstat.tcps_connects++;
1375 soisconnected(so);
1376 /* Do window scaling on this connection? */
61896e3c 1377 if ((tp->t_flags & (TF_RCVD_SCALE | TF_REQ_SCALE)) ==
b5572302 1378 (TF_RCVD_SCALE | TF_REQ_SCALE)) {
984263bc
MD
1379 tp->snd_scale = tp->requested_s_scale;
1380 tp->rcv_scale = tp->request_r_scale;
1381 }
1382 /* Segment is acceptable, update cache if undefined. */
1383 if (taop->tao_ccsent == 0)
1384 taop->tao_ccsent = to.to_ccecho;
1385
1386 tp->rcv_adv += tp->rcv_wnd;
1387 tp->snd_una++; /* SYN is acked */
91489f6b 1388 callout_stop(tp->tt_rexmt);
984263bc
MD
1389 /*
1390 * If there's data, delay ACK; if there's also a FIN
1391 * ACKNOW will be turned on later.
1392 */
1393 if (DELAY_ACK(tp) && tlen != 0)
61896e3c
JH
1394 callout_reset(tp->tt_delack, tcp_delacktime,
1395 tcp_timer_delack, tp);
984263bc
MD
1396 else
1397 tp->t_flags |= TF_ACKNOW;
1398 /*
1399 * Received <SYN,ACK> in SYN_SENT[*] state.
1400 * Transitions:
1401 * SYN_SENT --> ESTABLISHED
1402 * SYN_SENT* --> FIN_WAIT_1
1403 */
1404 tp->t_starttime = ticks;
1405 if (tp->t_flags & TF_NEEDFIN) {
1406 tp->t_state = TCPS_FIN_WAIT_1;
1407 tp->t_flags &= ~TF_NEEDFIN;
1408 thflags &= ~TH_SYN;
1409 } else {
1410 tp->t_state = TCPS_ESTABLISHED;
1411 callout_reset(tp->tt_keep, tcp_keepidle,
1412 tcp_timer_keep, tp);
1413 }
1414 } else {
1415 /*
95b22adf
JH
1416 * Received initial SYN in SYN-SENT[*] state =>
1417 * simultaneous open. If segment contains CC option
1418 * and there is a cached CC, apply TAO test.
1419 * If it succeeds, connection is * half-synchronized.
1420 * Otherwise, do 3-way handshake:
61896e3c
JH
1421 * SYN-SENT -> SYN-RECEIVED
1422 * SYN-SENT* -> SYN-RECEIVED*
95b22adf
JH
1423 * If there was no CC option, clear cached CC value.
1424 */
984263bc
MD
1425 tp->t_flags |= TF_ACKNOW;
1426 callout_stop(tp->tt_rexmt);
1427 if (to.to_flags & TOF_CC) {
1428 if (taop->tao_cc != 0 &&
1429 CC_GT(to.to_cc, taop->tao_cc)) {
1430 /*
1431 * update cache and make transition:
61896e3c
JH
1432 * SYN-SENT -> ESTABLISHED*
1433 * SYN-SENT* -> FIN-WAIT-1*
984263bc
MD
1434 */
1435 taop->tao_cc = to.to_cc;
1436 tp->t_starttime = ticks;
1437 if (tp->t_flags & TF_NEEDFIN) {
1438 tp->t_state = TCPS_FIN_WAIT_1;
1439 tp->t_flags &= ~TF_NEEDFIN;
1440 } else {
1441 tp->t_state = TCPS_ESTABLISHED;
1442 callout_reset(tp->tt_keep,
1443 tcp_keepidle,
1444 tcp_timer_keep,
1445 tp);
1446 }
1447 tp->t_flags |= TF_NEEDSYN;
1448 } else
1449 tp->t_state = TCPS_SYN_RECEIVED;
1450 } else {
1451 /* CC.NEW or no option => invalidate cache */
1452 taop->tao_cc = 0;
1453 tp->t_state = TCPS_SYN_RECEIVED;
1454 }
1455 }
1456
1457trimthenstep6:
1458 /*
1459 * Advance th->th_seq to correspond to first data byte.
1460 * If data, trim to stay within window,
1461 * dropping FIN if necessary.
1462 */
1463 th->th_seq++;
1464 if (tlen > tp->rcv_wnd) {
1465 todrop = tlen - tp->rcv_wnd;
1466 m_adj(m, -todrop);
1467 tlen = tp->rcv_wnd;
1468 thflags &= ~TH_FIN;
1469 tcpstat.tcps_rcvpackafterwin++;
1470 tcpstat.tcps_rcvbyteafterwin += todrop;
1471 }
1472 tp->snd_wl1 = th->th_seq - 1;
1473 tp->rcv_up = th->th_seq;
1474 /*
1475 * Client side of transaction: already sent SYN and data.
1476 * If the remote host used T/TCP to validate the SYN,
1477 * our data will be ACK'd; if so, enter normal data segment
1478 * processing in the middle of step 5, ack processing.
1479 * Otherwise, goto step 6.
1480 */
95b22adf 1481 if (thflags & TH_ACK)
984263bc
MD
1482 goto process_ACK;
1483
1484 goto step6;
1485
1486 /*
1487 * If the state is LAST_ACK or CLOSING or TIME_WAIT:
1488 * if segment contains a SYN and CC [not CC.NEW] option:
61896e3c
JH
1489 * if state == TIME_WAIT and connection duration > MSL,
1490 * drop packet and send RST;
984263bc
MD
1491 *
1492 * if SEG.CC > CCrecv then is new SYN, and can implicitly
1493 * ack the FIN (and data) in retransmission queue.
61896e3c
JH
1494 * Complete close and delete TCPCB. Then reprocess
1495 * segment, hoping to find new TCPCB in LISTEN state;
984263bc
MD
1496 *
1497 * else must be old SYN; drop it.
61896e3c 1498 * else do normal processing.
984263bc
MD
1499 */
1500 case TCPS_LAST_ACK:
1501 case TCPS_CLOSING:
1502 case TCPS_TIME_WAIT:
1503 if ((thflags & TH_SYN) &&
1504 (to.to_flags & TOF_CC) && tp->cc_recv != 0) {
1505 if (tp->t_state == TCPS_TIME_WAIT &&
1506 (ticks - tp->t_starttime) > tcp_msl) {
1507 rstreason = BANDLIM_UNLIMITED;
1508 goto dropwithreset;
1509 }
1510 if (CC_GT(to.to_cc, tp->cc_recv)) {
1511 tp = tcp_close(tp);
1512 goto findpcb;
1513 }
1514 else
1515 goto drop;
1516 }
95b22adf 1517 break; /* continue normal processing */
984263bc
MD
1518 }
1519
1520 /*
1521 * States other than LISTEN or SYN_SENT.
1522 * First check the RST flag and sequence number since reset segments
1523 * are exempt from the timestamp and connection count tests. This
1524 * fixes a bug introduced by the Stevens, vol. 2, p. 960 bugfix
1525 * below which allowed reset segments in half the sequence space
1526 * to fall though and be processed (which gives forged reset
1527 * segments with a random sequence number a 50 percent chance of
1528 * killing a connection).
1529 * Then check timestamp, if present.
1530 * Then check the connection count, if present.
1531 * Then check that at least some bytes of segment are within
1532 * receive window. If segment begins before rcv_nxt,
1533 * drop leading data (and SYN); if nothing left, just ack.
1534 *
1535 *
1536 * If the RST bit is set, check the sequence number to see
1537 * if this is a valid reset segment.
1538 * RFC 793 page 37:
1539 * In all states except SYN-SENT, all reset (RST) segments
1540 * are validated by checking their SEQ-fields. A reset is
1541 * valid if its sequence number is in the window.
1542 * Note: this does not take into account delayed ACKs, so
1543 * we should test against last_ack_sent instead of rcv_nxt.
1544 * The sequence number in the reset segment is normally an
91489f6b 1545 * echo of our outgoing acknowledgement numbers, but some hosts
984263bc
MD
1546 * send a reset with the sequence number at the rightmost edge
1547 * of our receive window, and we have to handle this case.
1548 * If we have multiple segments in flight, the intial reset
1549 * segment sequence numbers will be to the left of last_ack_sent,
1550 * but they will eventually catch up.
1551 * In any case, it never made sense to trim reset segments to
1552 * fit the receive window since RFC 1122 says:
1553 * 4.2.2.12 RST Segment: RFC-793 Section 3.4
1554 *
1555 * A TCP SHOULD allow a received RST segment to include data.
1556 *
1557 * DISCUSSION
61896e3c
JH
1558 * It has been suggested that a RST segment could contain
1559 * ASCII text that encoded and explained the cause of the
91489f6b 1560 * RST. No standard has yet been established for such
61896e3c 1561 * data.
984263bc
MD
1562 *
1563 * If the reset segment passes the sequence number test examine
1564 * the state:
1565 * SYN_RECEIVED STATE:
1566 * If passive open, return to LISTEN state.
1567 * If active open, inform user that connection was refused.
1568 * ESTABLISHED, FIN_WAIT_1, FIN_WAIT_2, CLOSE_WAIT STATES:
1569 * Inform user that connection was reset, and close tcb.
1570 * CLOSING, LAST_ACK STATES:
1571 * Close the tcb.
1572 * TIME_WAIT STATE:
1573 * Drop the segment - see Stevens, vol. 2, p. 964 and
61896e3c 1574 * RFC 1337.
984263bc
MD
1575 */
1576 if (thflags & TH_RST) {
1577 if (SEQ_GEQ(th->th_seq, tp->last_ack_sent) &&
d4dbb5be 1578 SEQ_LEQ(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) {
984263bc
MD
1579 switch (tp->t_state) {
1580
1581 case TCPS_SYN_RECEIVED:
1582 so->so_error = ECONNREFUSED;
1583 goto close;
1584
1585 case TCPS_ESTABLISHED:
1586 case TCPS_FIN_WAIT_1:
1587 case TCPS_FIN_WAIT_2:
1588 case TCPS_CLOSE_WAIT:
1589 so->so_error = ECONNRESET;
1590 close:
1591 tp->t_state = TCPS_CLOSED;
1592 tcpstat.tcps_drops++;
1593 tp = tcp_close(tp);
1594 break;
1595
1596 case TCPS_CLOSING:
1597 case TCPS_LAST_ACK:
1598 tp = tcp_close(tp);
1599 break;
1600
1601 case TCPS_TIME_WAIT:
1602 break;
1603 }
1604 }
1605 goto drop;
1606 }
1607
1608 /*
1609 * RFC 1323 PAWS: If we have a timestamp reply on this segment
1610 * and it's less than ts_recent, drop it.
1611 */
61896e3c 1612 if ((to.to_flags & TOF_TS) && tp->ts_recent != 0 &&
984263bc
MD
1613 TSTMP_LT(to.to_tsval, tp->ts_recent)) {
1614
1615 /* Check to see if ts_recent is over 24 days old. */
1616 if ((int)(ticks - tp->ts_recent_age) > TCP_PAWS_IDLE) {
1617 /*
1618 * Invalidate ts_recent. If this segment updates
1619 * ts_recent, the age will be reset later and ts_recent
1620 * will get a valid value. If it does not, setting
1621 * ts_recent to zero will at least satisfy the
1622 * requirement that zero be placed in the timestamp
1623 * echo reply when ts_recent isn't valid. The
1624 * age isn't reset until we get a valid ts_recent
1625 * because we don't want out-of-order segments to be
1626 * dropped when ts_recent is old.
1627 */
1628 tp->ts_recent = 0;
1629 } else {
1630 tcpstat.tcps_rcvduppack++;
1631 tcpstat.tcps_rcvdupbyte += tlen;
1632 tcpstat.tcps_pawsdrop++;
1633 if (tlen)
1634 goto dropafterack;
1635 goto drop;
1636 }
1637 }
1638
1639 /*
1640 * T/TCP mechanism
1641 * If T/TCP was negotiated and the segment doesn't have CC,
1642 * or if its CC is wrong then drop the segment.
1643 * RST segments do not have to comply with this.
1644 */
1645 if ((tp->t_flags & (TF_REQ_CC|TF_RCVD_CC)) == (TF_REQ_CC|TF_RCVD_CC) &&
61896e3c 1646 (!(to.to_flags & TOF_CC) || tp->cc_recv != to.to_cc))
95b22adf 1647 goto dropafterack;
984263bc
MD
1648
1649 /*
1650 * In the SYN-RECEIVED state, validate that the packet belongs to
1651 * this connection before trimming the data to fit the receive
1652 * window. Check the sequence number versus IRS since we know
1653 * the sequence numbers haven't wrapped. This is a partial fix
1654 * for the "LAND" DoS attack.
1655 */
1656 if (tp->t_state == TCPS_SYN_RECEIVED && SEQ_LT(th->th_seq, tp->irs)) {
1657 rstreason = BANDLIM_RST_OPENPORT;
1658 goto dropwithreset;
1659 }
1660
1661 todrop = tp->rcv_nxt - th->th_seq;
1662 if (todrop > 0) {
91489f6b
JH
1663 if (TCP_DO_SACK(tp)) {
1664 /* Report duplicate segment at head of packet. */
1665 tp->reportblk.rblk_start = th->th_seq;
1666 tp->reportblk.rblk_end = th->th_seq + tlen;
1667 if (thflags & TH_FIN)
1668 ++tp->reportblk.rblk_end;
1669 if (SEQ_GT(tp->reportblk.rblk_end, tp->rcv_nxt))
1670 tp->reportblk.rblk_end = tp->rcv_nxt;
1671 tp->t_flags |= (TF_DUPSEG | TF_SACKLEFT | TF_ACKNOW);
1672 }
984263bc
MD
1673 if (thflags & TH_SYN) {
1674 thflags &= ~TH_SYN;
1675 th->th_seq++;
1676 if (th->th_urp > 1)
1677 th->th_urp--;
1678 else
1679 thflags &= ~TH_URG;
1680 todrop--;
1681 }
1682 /*
1683 * Following if statement from Stevens, vol. 2, p. 960.
1684 */
61896e3c
JH
1685 if (todrop > tlen ||
1686 (todrop == tlen && !(thflags & TH_FIN))) {
984263bc
MD
1687 /*
1688 * Any valid FIN must be to the left of the window.
1689 * At this point the FIN must be a duplicate or out
1690 * of sequence; drop it.
1691 */
1692 thflags &= ~TH_FIN;
1693
1694 /*
1695 * Send an ACK to resynchronize and drop any data.
1696 * But keep on processing for RST or ACK.
1697 */
1698 tp->t_flags |= TF_ACKNOW;
1699 todrop = tlen;
1700 tcpstat.tcps_rcvduppack++;
1701 tcpstat.tcps_rcvdupbyte += todrop;
1702 } else {
1703 tcpstat.tcps_rcvpartduppack++;
1704 tcpstat.tcps_rcvpartdupbyte += todrop;
1705 }
1706 drop_hdrlen += todrop; /* drop from the top afterwards */
1707 th->th_seq += todrop;
1708 tlen -= todrop;
1709 if (th->th_urp > todrop)
1710 th->th_urp -= todrop;
1711 else {
1712 thflags &= ~TH_URG;
1713 th->th_urp = 0;
1714 }
1715 }
1716
1717 /*
1718 * If new data are received on a connection after the
1719 * user processes are gone, then RST the other end.
1720 */
1721 if ((so->so_state & SS_NOFDREF) &&
1722 tp->t_state > TCPS_CLOSE_WAIT && tlen) {
1723 tp = tcp_close(tp);
1724 tcpstat.tcps_rcvafterclose++;
1725 rstreason = BANDLIM_UNLIMITED;
1726 goto dropwithreset;
1727 }
1728
1729 /*
1730 * If segment ends after window, drop trailing data
1731 * (and PUSH and FIN); if nothing left, just ACK.
1732 */
61896e3c 1733 todrop = (th->th_seq + tlen) - (tp->rcv_nxt + tp->rcv_wnd);
984263bc
MD
1734 if (todrop > 0) {
1735 tcpstat.tcps_rcvpackafterwin++;
1736 if (todrop >= tlen) {
1737 tcpstat.tcps_rcvbyteafterwin += tlen;
1738 /*
1739 * If a new connection request is received
1740 * while in TIME_WAIT, drop the old connection
1741 * and start over if the sequence numbers
1742 * are above the previous ones.
1743 */
1744 if (thflags & TH_SYN &&
1745 tp->t_state == TCPS_TIME_WAIT &&
1746 SEQ_GT(th->th_seq, tp->rcv_nxt)) {
1747 tp = tcp_close(tp);
1748 goto findpcb;
1749 }
1750 /*
1751 * If window is closed can only take segments at
1752 * window edge, and have to drop data and PUSH from
1753 * incoming segments. Continue processing, but
1754 * remember to ack. Otherwise, drop segment
1755 * and ack.
1756 */
1757 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) {
1758 tp->t_flags |= TF_ACKNOW;
1759 tcpstat.tcps_rcvwinprobe++;
1760 } else
1761 goto dropafterack;
1762 } else
1763 tcpstat.tcps_rcvbyteafterwin += todrop;
1764 m_adj(m, -todrop);
1765 tlen -= todrop;
61896e3c 1766 thflags &= ~(TH_PUSH | TH_FIN);
984263bc
MD
1767 }
1768
1769 /*
1770 * If last ACK falls within this segment's sequence numbers,
1771 * record its timestamp.
1772 * NOTE that the test is modified according to the latest
1773 * proposal of the tcplw@cray.com list (Braden 1993/04/26).
1774 */
61896e3c 1775 if ((to.to_flags & TOF_TS) && SEQ_LEQ(th->th_seq, tp->last_ack_sent)) {
984263bc
MD
1776 tp->ts_recent_age = ticks;
1777 tp->ts_recent = to.to_tsval;
1778 }
1779
1780 /*
1781 * If a SYN is in the window, then this is an
1782 * error and we send an RST and drop the connection.
1783 */
1784 if (thflags & TH_SYN) {
1785 tp = tcp_drop(tp, ECONNRESET);
1786 rstreason = BANDLIM_UNLIMITED;
1787 goto dropwithreset;
1788 }
1789
1790 /*
1791 * If the ACK bit is off: if in SYN-RECEIVED state or SENDSYN
1792 * flag is on (half-synchronized state), then queue data for
1793 * later processing; else drop segment and return.
1794 */
61896e3c 1795 if (!(thflags & TH_ACK)) {
984263bc
MD
1796 if (tp->t_state == TCPS_SYN_RECEIVED ||
1797 (tp->t_flags & TF_NEEDSYN))
1798 goto step6;
1799 else
1800 goto drop;
1801 }
1802
1803 /*
1804 * Ack processing.
1805 */
1806 switch (tp->t_state) {
984263bc 1807 /*
91489f6b 1808 * In SYN_RECEIVED state, the ACK acknowledges our SYN, so enter
984263bc
MD
1809 * ESTABLISHED state and continue processing.
1810 * The ACK was checked above.
1811 */
1812 case TCPS_SYN_RECEIVED:
1813
1814 tcpstat.tcps_connects++;
1815 soisconnected(so);
1816 /* Do window scaling? */
61896e3c 1817 if ((tp->t_flags & (TF_RCVD_SCALE | TF_REQ_SCALE)) ==
b5572302 1818 (TF_RCVD_SCALE | TF_REQ_SCALE)) {
984263bc
MD
1819 tp->snd_scale = tp->requested_s_scale;
1820 tp->rcv_scale = tp->request_r_scale;
1821 }
1822 /*
1823 * Upon successful completion of 3-way handshake,
1824 * update cache.CC if it was undefined, pass any queued
1825 * data to the user, and advance state appropriately.
1826 */
1827 if ((taop = tcp_gettaocache(&inp->inp_inc)) != NULL &&
1828 taop->tao_cc == 0)
1829 taop->tao_cc = tp->cc_recv;
1830
1831 /*
1832 * Make transitions:
1833 * SYN-RECEIVED -> ESTABLISHED
1834 * SYN-RECEIVED* -> FIN-WAIT-1
1835 */
1836 tp->t_starttime = ticks;
1837 if (tp->t_flags & TF_NEEDFIN) {
1838 tp->t_state = TCPS_FIN_WAIT_1;
1839 tp->t_flags &= ~TF_NEEDFIN;
1840 } else {
1841 tp->t_state = TCPS_ESTABLISHED;
d24ce1dc 1842 callout_reset(tp->tt_keep, tcp_keepidle,
984263bc
MD
1843 tcp_timer_keep, tp);
1844 }
1845 /*
1846 * If segment contains data or ACK, will call tcp_reass()
1847 * later; if not, do so now to pass queued data to user.
1848 */
61896e3c
JH
1849 if (tlen == 0 && !(thflags & TH_FIN))
1850 (void) tcp_reass(tp, NULL, NULL, NULL);
984263bc
MD
1851 /* fall into ... */
1852
1853 /*
1854 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range
1855 * ACKs. If the ack is in the range
1856 * tp->snd_una < th->th_ack <= tp->snd_max
1857 * then advance tp->snd_una to th->th_ack and drop
1858 * data from the retransmission queue. If this ACK reflects
1859 * more up to date window information we update our window information.
1860 */
1861 case TCPS_ESTABLISHED:
1862 case TCPS_FIN_WAIT_1:
1863 case TCPS_FIN_WAIT_2:
1864 case TCPS_CLOSE_WAIT:
1865 case TCPS_CLOSING:
1866 case TCPS_LAST_ACK:
1867 case TCPS_TIME_WAIT:
1868
1869 if (SEQ_LEQ(th->th_ack, tp->snd_una)) {
91489f6b
JH
1870 if (TCP_DO_SACK(tp))
1871 tcp_sack_update_scoreboard(tp, &to);
95b22adf
JH
1872 if (tlen != 0 || tiwin != tp->snd_wnd) {
1873 tp->t_dupacks = 0;
1874 break;
1875 }
1876 tcpstat.tcps_rcvdupack++;
91489f6b
JH
1877 if (!callout_active(tp->tt_rexmt) ||
1878 th->th_ack != tp->snd_una) {
1879 tp->t_dupacks = 0;
1880 break;
1881 }
95b22adf 1882 /*
91489f6b 1883 * We have outstanding data (other than
95b22adf
JH
1884 * a window probe), this is a completely
1885 * duplicate ack (ie, window info didn't
1886 * change), the ack is the biggest we've
1887 * seen and we've seen exactly our rexmt
91489f6b 1888 * threshhold of them, so assume a packet
95b22adf
JH
1889 * has been dropped and retransmit it.
1890 * Kludge snd_nxt & the congestion
1891 * window so we send only this one
1892 * packet.
95b22adf 1893 */
91489f6b
JH
1894 if (IN_FASTRECOVERY(tp)) {
1895 if (TCP_DO_SACK(tp)) {
1896 /* No artifical cwnd inflation. */
1897 tcp_sack_rexmt(tp, th);
1898 } else {
1899 /*
1900 * Dup acks mean that packets
1901 * have left the network
1902 * (they're now cached at the
1903 * receiver) so bump cwnd by
1904 * the amount in the receiver
1905 * to keep a constant cwnd
1906 * packets in the network.
1907 */
1908 tp->snd_cwnd += tp->t_maxseg;
1909 (void) tcp_output(tp);
1910 }
1911 } else if (SEQ_LT(th->th_ack, tp->snd_recover)) {
95b22adf
JH
1912 tp->t_dupacks = 0;
1913 break;
95b22adf 1914 } else if (++tp->t_dupacks == tcprexmtthresh) {
91489f6b 1915 tcp_seq old_snd_nxt;
95b22adf
JH
1916 u_int win;
1917
8819433a 1918fastretransmit:
95b22adf
JH
1919 if (tcp_do_eifel_detect &&
1920 (tp->t_flags & TF_RCVD_TSTMP)) {
1921 tcp_save_congestion_state(tp);
1922 tp->t_flags |= TF_FASTREXMT;
1923 }
91489f6b
JH
1924 /*
1925 * We know we're losing at the current
1926 * window size, so do congestion avoidance:
1927 * set ssthresh to half the current window
1928 * and pull our congestion window back to the
1929 * new ssthresh.
1930 */
95b22adf
JH
1931 win = min(tp->snd_wnd, tp->snd_cwnd) / 2 /
1932 tp->t_maxseg;
1933 if (win < 2)
1934 win = 2;
1935 tp->snd_ssthresh = win * tp->t_maxseg;
1936 ENTER_FASTRECOVERY(tp);
1937 tp->snd_recover = tp->snd_max;
1938 callout_stop(tp->tt_rexmt);
1939 tp->t_rtttime = 0;
91489f6b 1940 old_snd_nxt = tp->snd_nxt;
95b22adf
JH
1941 tp->snd_nxt = th->th_ack;
1942 tp->snd_cwnd = tp->t_maxseg;
1943 (void) tcp_output(tp);
1944 ++tcpstat.tcps_sndfastrexmit;
91489f6b
JH
1945 tp->snd_cwnd = tp->snd_ssthresh;
1946 tp->rexmt_high = tp->snd_nxt;
1947 if (SEQ_GT(old_snd_nxt, tp->snd_nxt))
1948 tp->snd_nxt = old_snd_nxt;
95b22adf
JH
1949 KASSERT(tp->snd_limited <= 2,
1950 ("tp->snd_limited too big"));
91489f6b
JH
1951 if (TCP_DO_SACK(tp))
1952 tcp_sack_rexmt(tp, th);
1953 else
1954 tp->snd_cwnd += tp->t_maxseg *
1955 (tp->t_dupacks - tp->snd_limited);
95b22adf
JH
1956 } else if (tcp_do_limitedtransmit) {
1957 u_long oldcwnd = tp->snd_cwnd;
1958 tcp_seq oldsndmax = tp->snd_max;
1959 /* outstanding data */
1960 uint32_t ownd = tp->snd_max - tp->snd_una;
1961 u_int sent;
ca94b4a6 1962
8819433a
JH
1963#define iceildiv(n, d) (((n)+(d)-1) / (d))
1964
95b22adf
JH
1965 KASSERT(tp->t_dupacks == 1 ||
1966 tp->t_dupacks == 2,
1967 ("dupacks not 1 or 2"));
1968 if (tp->t_dupacks == 1)
1969 tp->snd_limited = 0;
1970 tp->snd_cwnd = ownd +
1971 (tp->t_dupacks - tp->snd_limited) *
1972 tp->t_maxseg;
1973 (void) tcp_output(tp);
1974 tp->snd_cwnd = oldcwnd;
1975 sent = tp->snd_max - oldsndmax;
1976 if (sent > tp->t_maxseg) {
1977 KASSERT((tp->t_dupacks == 2 &&
1978 tp->snd_limited == 0) ||
1979 (sent == tp->t_maxseg + 1 &&
1980 tp->t_flags & TF_SENTFIN),
1981 ("sent too much"));
1982 KASSERT(sent <= tp->t_maxseg * 2,
1983 ("sent too many segments"));
1984 tp->snd_limited = 2;
1985 tcpstat.tcps_sndlimited += 2;
1986 } else if (sent > 0) {
1987 ++tp->snd_limited;
1988 ++tcpstat.tcps_sndlimited;
1989 } else if (tcp_do_early_retransmit &&
1990 (tcp_do_eifel_detect &&
1991 (tp->t_flags & TF_RCVD_TSTMP)) &&
91489f6b 1992 ownd < 4 * tp->t_maxseg &&
95b22adf 1993 tp->t_dupacks + 1 >=
91489f6b
JH
1994 iceildiv(ownd, tp->t_maxseg) &&
1995 (!TCP_DO_SACK(tp) ||
1996 ownd <= tp->t_maxseg ||
1997 tcp_sack_has_sacked(&tp->scb,
1998 ownd - tp->t_maxseg))) {
95b22adf
JH
1999 ++tcpstat.tcps_sndearlyrexmit;
2000 tp->t_flags |= TF_EARLYREXMT;
2001 goto fastretransmit;
984263bc 2002 }
95b22adf
JH
2003 }
2004 goto drop;
984263bc
MD
2005 }
2006
2007 KASSERT(SEQ_GT(th->th_ack, tp->snd_una), ("th_ack <= snd_una"));
984263bc
MD
2008 tp->t_dupacks = 0;
2009 if (SEQ_GT(th->th_ack, tp->snd_max)) {
5a274421
JH
2010 /*
2011 * Detected optimistic ACK attack.
2012 * Force slow-start to de-synchronize attack.
2013 */
2014 tp->snd_cwnd = tp->t_maxseg;
2015
984263bc
MD
2016 tcpstat.tcps_rcvacktoomuch++;
2017 goto dropafterack;
2018 }
2019 /*
2020 * If we reach this point, ACK is not a duplicate,
2021 * i.e., it ACKs something we sent.
2022 */
2023 if (tp->t_flags & TF_NEEDSYN) {
2024 /*
2025 * T/TCP: Connection was half-synchronized, and our
2026 * SYN has been ACK'd (so connection is now fully
2027 * synchronized). Go to non-starred state,
2028 * increment snd_una for ACK of SYN, and check if
2029 * we can do window scaling.
2030 */
2031 tp->t_flags &= ~TF_NEEDSYN;
2032 tp->snd_una++;
2033 /* Do window scaling? */
61896e3c
JH
2034 if ((tp->t_flags & (TF_RCVD_SCALE | TF_REQ_SCALE)) ==
2035 (TF_RCVD_SCALE | TF_REQ_SCALE)) {
984263bc
MD
2036 tp->snd_scale = tp->requested_s_scale;
2037 tp->rcv_scale = tp->request_r_scale;
2038 }
2039 }
2040
2041process_ACK:
2042 acked = th->th_ack - tp->snd_una;
2043 tcpstat.tcps_rcvackpack++;
2044 tcpstat.tcps_rcvackbyte += acked;
2045
b5572302 2046 if (tcp_do_eifel_detect && acked > 0 &&
95b22adf 2047 (to.to_flags & TOF_TS) && (to.to_tsecr != 0) &&
bfdb979e
JH
2048 (tp->t_flags & TF_FIRSTACCACK)) {
2049 /* Eifel detection applicable. */
2050 if (to.to_tsecr < tp->t_rexmtTS) {
bfdb979e 2051 ++tcpstat.tcps_eifeldetected;
8819433a
JH
2052 tcp_revert_congestion_state(tp);
2053 if (tp->t_rxtshift == 1 &&
2054 ticks >= tp->t_badrxtwin)
2055 ++tcpstat.tcps_rttcantdetect;
bfdb979e
JH
2056 }
2057 } else if (tp->t_rxtshift == 1 && ticks < tp->t_badrxtwin) {
b5572302
JH
2058 /*
2059 * If we just performed our first retransmit,
2060 * and the ACK arrives within our recovery window,
2061 * then it was a mistake to do the retransmit
91489f6b 2062 * in the first place. Recover our original cwnd
b5572302
JH
2063 * and ssthresh, and proceed to transmit where we
2064 * left off.
2065 */
bfdb979e
JH
2066 tcp_revert_congestion_state(tp);
2067 ++tcpstat.tcps_rttdetected;
984263bc
MD
2068 }
2069
2070 /*
2071 * If we have a timestamp reply, update smoothed
2072 * round trip time. If no timestamp is present but
2073 * transmit timer is running and timed sequence
2074 * number was acked, update smoothed round trip time.
2075 * Since we now have an rtt measurement, cancel the
2076 * timer backoff (cf., Phil Karn's retransmit alg.).
2077 * Recompute the initial retransmit timer.
2078 *
2079 * Some machines (certain windows boxes) send broken
d24ce1dc 2080 * timestamp replies during the SYN+ACK phase, ignore
984263bc
MD
2081 * timestamps of 0.
2082 */
95b22adf 2083 if ((to.to_flags & TOF_TS) && (to.to_tsecr != 0))
984263bc 2084 tcp_xmit_timer(tp, ticks - to.to_tsecr + 1);
95b22adf 2085 else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq))
984263bc 2086 tcp_xmit_timer(tp, ticks - tp->t_rtttime);
984263bc
MD
2087 tcp_xmit_bandwidth_limit(tp, th->th_ack);
2088
984263bc
MD
2089 /*
2090 * If no data (only SYN) was ACK'd,
2091 * skip rest of ACK processing.
2092 */
2093 if (acked == 0)
2094 goto step6;
2095
efd4b327 2096 /* Stop looking for an acceptable ACK since one was received. */
8819433a 2097 tp->t_flags &= ~(TF_FIRSTACCACK | TF_FASTREXMT | TF_EARLYREXMT);
efd4b327 2098
984263bc
MD
2099 if (acked > so->so_snd.sb_cc) {
2100 tp->snd_wnd -= so->so_snd.sb_cc;
2101 sbdrop(&so->so_snd, (int)so->so_snd.sb_cc);
61896e3c 2102 ourfinisacked = TRUE;
984263bc
MD
2103 } else {
2104 sbdrop(&so->so_snd, acked);
2105 tp->snd_wnd -= acked;
61896e3c 2106 ourfinisacked = FALSE;
984263bc
MD
2107 }
2108 sowwakeup(so);
91489f6b
JH
2109
2110 /*
2111 * Update window information.
2112 * Don't look at window if no ACK:
2113 * TAC's send garbage on first SYN.
2114 */
2115 if (SEQ_LT(tp->snd_wl1, th->th_seq) ||
2116 (tp->snd_wl1 == th->th_seq &&
2117 (SEQ_LT(tp->snd_wl2, th->th_ack) ||
2118 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd)))) {
2119 /* keep track of pure window updates */
2120 if (tlen == 0 && tp->snd_wl2 == th->th_ack &&
2121 tiwin > tp->snd_wnd)
2122 tcpstat.tcps_rcvwinupd++;
2123 tp->snd_wnd = tiwin;
2124 tp->snd_wl1 = th->th_seq;
2125 tp->snd_wl2 = th->th_ack;
2126 if (tp->snd_wnd > tp->max_sndwnd)
2127 tp->max_sndwnd = tp->snd_wnd;
2128 needoutput = TRUE;
2129 }
2130
2131 tp->snd_una = th->th_ack;
2132 if (TCP_DO_SACK(tp))
2133 tcp_sack_update_scoreboard(tp, &to);
95b22adf 2134 if (IN_FASTRECOVERY(tp)) {
91489f6b 2135 if (SEQ_GEQ(th->th_ack, tp->snd_recover)) {
95b22adf 2136 EXIT_FASTRECOVERY(tp);
91489f6b
JH
2137 needoutput = TRUE;
2138 /*
2139 * If the congestion window was inflated
2140 * to account for the other side's
2141 * cached packets, retract it.
2142 *
2143 * Window inflation should have left us
2144 * with approximately snd_ssthresh outstanding
2145 * data. But, in case we would be inclined
2146 * to send a burst, better do it using
2147 * slow start.
2148 */
2149 if (!TCP_DO_SACK(tp))
2150 tp->snd_cwnd = tp->snd_ssthresh;
2151
2152 if (SEQ_GT(th->th_ack + tp->snd_cwnd,
2153 tp->snd_max + 2 * tp->t_maxseg))
2154 tp->snd_cwnd =
2155 (tp->snd_max - tp->snd_una) +
2156 2 * tp->t_maxseg;
2157 } else {
2158 if (TCP_DO_SACK(tp)) {
2159 tp->snd_max_rexmt = tp->snd_max;
2160 tcp_sack_rexmt(tp, th);
2161 } else {
2162 tcp_newreno_partial_ack(tp, th, acked);
2163 }
2164 needoutput = FALSE;
2165 }
95b22adf 2166 } else {
91489f6b
JH
2167 /*
2168 * When new data is acked, open the congestion window.
2169 * If the window gives us less than ssthresh packets
2170 * in flight, open exponentially (maxseg per packet).
2171 * Otherwise open linearly: maxseg per window
2172 * (maxseg^2 / cwnd per packet).
2173 */
2174 u_int cw = tp->snd_cwnd;
2175 u_int incr;
2176
2177 if (cw > tp->snd_ssthresh)
2178 incr = tp->t_maxseg * tp->t_maxseg / cw;
2179 else
2180 incr = tp->t_maxseg;
2181 tp->snd_cwnd = min(cw+incr, TCP_MAXWIN<<tp->snd_scale);
95b22adf 2182 tp->snd_recover = th->th_ack - 1;
cfb3f3f4 2183 }
984263bc
MD
2184 if (SEQ_LT(tp->snd_nxt, tp->snd_una))
2185 tp->snd_nxt = tp->snd_una;
2186
91489f6b
JH
2187 /*
2188 * If all outstanding data is acked, stop retransmit
2189 * timer and remember to restart (more output or persist).
2190 * If there is more data to be acked, restart retransmit
2191 * timer, using current (possibly backed-off) value.
2192 */
2193 if (th->th_ack == tp->snd_max) {
2194 callout_stop(tp->tt_rexmt);
2195 needoutput = TRUE;
2196 } else if (!callout_active(tp->tt_persist))
2197 callout_reset(tp->tt_rexmt, tp->t_rxtcur,
2198 tcp_timer_rexmt, tp);
2199
984263bc 2200 switch (tp->t_state) {
984263bc
MD
2201 /*
2202 * In FIN_WAIT_1 STATE in addition to the processing
2203 * for the ESTABLISHED state if our FIN is now acknowledged
2204 * then enter FIN_WAIT_2.
2205 */
2206 case TCPS_FIN_WAIT_1:
2207 if (ourfinisacked) {
2208 /*
2209 * If we can't receive any more
2210 * data, then closing user can proceed.
2211 * Starting the timer is contrary to the
2212 * specification, but if we don't get a FIN
2213 * we'll hang forever.
2214 */
2215 if (so->so_state & SS_CANTRCVMORE) {
2216 soisdisconnected(so);
2217 callout_reset(tp->tt_2msl, tcp_maxidle,
2218 tcp_timer_2msl, tp);
2219 }
2220 tp->t_state = TCPS_FIN_WAIT_2;
2221 }
2222 break;
2223
95b22adf 2224 /*
984263bc
MD
2225 * In CLOSING STATE in addition to the processing for
2226 * the ESTABLISHED state if the ACK acknowledges our FIN
2227 * then enter the TIME-WAIT state, otherwise ignore
2228 * the segment.
2229 */
2230 case TCPS_CLOSING:
2231 if (ourfinisacked) {
2232 tp->t_state = TCPS_TIME_WAIT;
2233 tcp_canceltimers(tp);
2234 /* Shorten TIME_WAIT [RFC-1644, p.28] */
2235 if (tp->cc_recv != 0 &&
2236 (ticks - tp->t_starttime) < tcp_msl)
2237 callout_reset(tp->tt_2msl,
b5572302
JH
2238 tp->t_rxtcur * TCPTV_TWTRUNC,
2239 tcp_timer_2msl, tp);
984263bc
MD
2240 else
2241 callout_reset(tp->tt_2msl, 2 * tcp_msl,
b5572302 2242 tcp_timer_2msl, tp);
984263bc
MD
2243 soisdisconnected(so);
2244 }
2245 break;
2246
2247 /*
2248 * In LAST_ACK, we may still be waiting for data to drain
2249 * and/or to be acked, as well as for the ack of our FIN.
2250 * If our FIN is now acknowledged, delete the TCB,
2251 * enter the closed state and return.
2252 */
2253 case TCPS_LAST_ACK:
2254 if (ourfinisacked) {
2255 tp = tcp_close(tp);
2256 goto drop;
2257 }
2258 break;
2259
2260 /*
2261 * In TIME_WAIT state the only thing that should arrive
2262 * is a retransmission of the remote FIN. Acknowledge
2263 * it and restart the finack timer.
2264 */
2265 case TCPS_TIME_WAIT:
2266 callout_reset(tp->tt_2msl, 2 * tcp_msl,
2267 tcp_timer_2msl, tp);
2268 goto dropafterack;
2269 }
2270 }
2271
2272step6:
2273 /*
2274 * Update window information.
2275 * Don't look at window if no ACK: TAC's send garbage on first SYN.
2276 */
2277 if ((thflags & TH_ACK) &&
df9d7670 2278 acceptable_window_update(tp, th, tiwin)) {
984263bc 2279 /* keep track of pure window updates */
b5572302
JH
2280 if (tlen == 0 && tp->snd_wl2 == th->th_ack &&
2281 tiwin > tp->snd_wnd)
984263bc
MD
2282 tcpstat.tcps_rcvwinupd++;
2283 tp->snd_wnd = tiwin;
2284 tp->snd_wl1 = th->th_seq;
2285 tp->snd_wl2 = th->th_ack;
2286 if (tp->snd_wnd > tp->max_sndwnd)
2287 tp->max_sndwnd = tp->snd_wnd;
61896e3c 2288 needoutput = TRUE;
984263bc
MD
2289 }
2290
2291 /*
2292 * Process segments with URG.
2293 */
2294 if ((thflags & TH_URG) && th->th_urp &&
95b22adf 2295 !TCPS_HAVERCVDFIN(tp->t_state)) {
984263bc
MD
2296 /*
2297 * This is a kludge, but if we receive and accept
2298 * random urgent pointers, we'll crash in
2299 * soreceive. It's hard to imagine someone
2300 * actually wanting to send this much urgent data.
2301 */
2302 if (th->th_urp + so->so_rcv.sb_cc > sb_max) {
2303 th->th_urp = 0; /* XXX */
2304 thflags &= ~TH_URG; /* XXX */
2305 goto dodata; /* XXX */
2306 }
2307 /*
2308 * If this segment advances the known urgent pointer,
2309 * then mark the data stream. This should not happen
2310 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since
2311 * a FIN has been received from the remote side.
2312 * In these states we ignore the URG.
2313 *
2314 * According to RFC961 (Assigned Protocols),
2315 * the urgent pointer points to the last octet
2316 * of urgent data. We continue, however,
2317 * to consider it to indicate the first octet
2318 * of data past the urgent section as the original
2319 * spec states (in one of two places).
2320 */
61896e3c 2321 if (SEQ_GT(th->th_seq + th->th_urp, tp->rcv_up)) {
984263bc
MD
2322 tp->rcv_up = th->th_seq + th->th_urp;
2323 so->so_oobmark = so->so_rcv.sb_cc +
2324 (tp->rcv_up - tp->rcv_nxt) - 1;
2325 if (so->so_oobmark == 0)
2326 so->so_state |= SS_RCVATMARK;
2327 sohasoutofband(so);
2328 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA);
2329 }
2330 /*
2331 * Remove out of band data so doesn't get presented to user.
2332 * This can happen independent of advancing the URG pointer,
2333 * but if two URG's are pending at once, some out-of-band
2334 * data may creep in... ick.
2335 */
61896e3c
JH
2336 if (th->th_urp <= (u_long)tlen &&
2337 !(so->so_options & SO_OOBINLINE)) {
2338 /* hdr drop is delayed */
2339 tcp_pulloutofband(so, th, m, drop_hdrlen);
2340 }
984263bc
MD
2341 } else {
2342 /*
2343 * If no out of band data is expected,
2344 * pull receive urgent pointer along
2345 * with the receive window.
2346 */
2347 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up))
2348 tp->rcv_up = tp->rcv_nxt;
2349 }
984263bc 2350
61896e3c 2351dodata: /* XXX */
984263bc
MD
2352 /*
2353 * Process the segment text, merging it into the TCP sequencing queue,
2354 * and arranging for acknowledgment of receipt if necessary.
2355 * This process logically involves adjusting tp->rcv_wnd as data
2356 * is presented to the user (this happens in tcp_usrreq.c,
2357 * case PRU_RCVD). If a FIN has already been received on this
2358 * connection then we just ignore the text.
2359 */
95b22adf 2360 if ((tlen || (thflags & TH_FIN)) && !TCPS_HAVERCVDFIN(tp->t_state)) {
984263bc
MD
2361 m_adj(m, drop_hdrlen); /* delayed header drop */
2362 /*
2363 * Insert segment which includes th into TCP reassembly queue
2364 * with control block tp. Set thflags to whether reassembly now
2365 * includes a segment with FIN. This handles the common case
2366 * inline (segment is the next to be received on an established
2367 * connection, and the queue is empty), avoiding linkage into
2368 * and removal from the queue and repetition of various
2369 * conversions.
2370 * Set DELACK for segments received in order, but ack
2371 * immediately when segments are out of order (so
2372 * fast retransmit can work).
2373 */
2374 if (th->th_seq == tp->rcv_nxt &&
2375 LIST_EMPTY(&tp->t_segq) &&
2376 TCPS_HAVEESTABLISHED(tp->t_state)) {
2377 if (DELAY_ACK(tp))
2378 callout_reset(tp->tt_delack, tcp_delacktime,
2379 tcp_timer_delack, tp);
2380 else
2381 tp->t_flags |= TF_ACKNOW;
2382 tp->rcv_nxt += tlen;
2383 thflags = th->th_flags & TH_FIN;
2384 tcpstat.tcps_rcvpack++;
2385 tcpstat.tcps_rcvbyte += tlen;
2386 ND6_HINT(tp);
2387 if (so->so_state & SS_CANTRCVMORE)
2388 m_freem(m);
2389 else
507106e0 2390 sbappendstream(&so->so_rcv, m);
984263bc
MD
2391 sorwakeup(so);
2392 } else {
91489f6b
JH
2393 if (!(tp->t_flags & TF_DUPSEG)) {
2394 /* Initialize SACK report block. */
2395 tp->reportblk.rblk_start = th->th_seq;
2396 tp->reportblk.rblk_end = th->th_seq + tlen +
2397 ((thflags & TH_FIN) != 0);
2398 }
984263bc
MD
2399 thflags = tcp_reass(tp, th, &tlen, m);
2400 tp->t_flags |= TF_ACKNOW;
2401 }
2402
2403 /*
2404 * Note the amount of data that peer has sent into
2405 * our window, in order to estimate the sender's
2406 * buffer size.
2407 */
2408 len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt);
2409 } else {
2410 m_freem(m);
2411 thflags &= ~TH_FIN;
2412 }
2413
2414 /*
2415 * If FIN is received ACK the FIN and let the user know
2416 * that the connection is closing.
2417 */
2418 if (thflags & TH_FIN) {
95b22adf 2419 if (!TCPS_HAVERCVDFIN(tp->t_state)) {
984263bc
MD
2420 socantrcvmore(so);
2421 /*
2422 * If connection is half-synchronized
2423 * (ie NEEDSYN flag on) then delay ACK,
2424 * so it may be piggybacked when SYN is sent.
2425 * Otherwise, since we received a FIN then no
2426 * more input can be expected, send ACK now.
2427 */
2428 if (DELAY_ACK(tp) && (tp->t_flags & TF_NEEDSYN))
61896e3c
JH
2429 callout_reset(tp->tt_delack, tcp_delacktime,
2430 tcp_timer_delack, tp);
984263bc
MD
2431 else
2432 tp->t_flags |= TF_ACKNOW;
2433 tp->rcv_nxt++;
2434 }
984263bc 2435
61896e3c 2436 switch (tp->t_state) {
95b22adf 2437 /*
984263bc
MD
2438 * In SYN_RECEIVED and ESTABLISHED STATES
2439 * enter the CLOSE_WAIT state.
2440 */
2441 case TCPS_SYN_RECEIVED:
2442 tp->t_starttime = ticks;
2443 /*FALLTHROUGH*/
2444 case TCPS_ESTABLISHED:
2445 tp->t_state = TCPS_CLOSE_WAIT;
2446 break;
2447
95b22adf 2448 /*
984263bc
MD
2449 * If still in FIN_WAIT_1 STATE FIN has not been acked so
2450 * enter the CLOSING state.
2451 */
2452 case TCPS_FIN_WAIT_1:
2453 tp->t_state = TCPS_CLOSING;
2454 break;
2455
95b22adf 2456 /*
984263bc
MD
2457 * In FIN_WAIT_2 state enter the TIME_WAIT state,
2458 * starting the time-wait timer, turning off the other
2459 * standard timers.
2460 */
2461 case TCPS_FIN_WAIT_2:
2462 tp->t_state = TCPS_TIME_WAIT;
2463 tcp_canceltimers(tp);
2464 /* Shorten TIME_WAIT [RFC-1644, p.28] */
2465 if (tp->cc_recv != 0 &&
2466 (ticks - tp->t_starttime) < tcp_msl) {
2467 callout_reset(tp->tt_2msl,
2468 tp->t_rxtcur * TCPTV_TWTRUNC,
2469 tcp_timer_2msl, tp);
2470 /* For transaction client, force ACK now. */
2471 tp->t_flags |= TF_ACKNOW;
2472 }
2473 else
2474 callout_reset(tp->tt_2msl, 2 * tcp_msl,
2475 tcp_timer_2msl, tp);
2476 soisdisconnected(so);
2477 break;
2478
2479 /*
2480 * In TIME_WAIT state restart the 2 MSL time_wait timer.
2481 */
2482 case TCPS_TIME_WAIT:
2483 callout_reset(tp->tt_2msl, 2 * tcp_msl,
2484 tcp_timer_2msl, tp);
2485 break;
2486 }
2487 }
61896e3c 2488
984263bc
MD
2489#ifdef TCPDEBUG
2490 if (so->so_options & SO_DEBUG)
2491 tcp_trace(TA_INPUT, ostate, tp, (void *)tcp_saveipgen,
2492 &tcp_savetcp, 0);
2493#endif
2494
2495 /*
2496 * Return any desired output.
2497 */
2498 if (needoutput || (tp->t_flags & TF_ACKNOW))
2499 (void) tcp_output(tp);
2500 return;
2501
2502dropafterack:
2503 /*
2504 * Generate an ACK dropping incoming segment if it occupies
2505 * sequence space, where the ACK reflects our state.
2506 *
2507 * We can now skip the test for the RST flag since all
2508 * paths to this code happen after packets containing
2509 * RST have been dropped.
2510 *
2511 * In the SYN-RECEIVED state, don't send an ACK unless the
2512 * segment we received passes the SYN-RECEIVED ACK test.
2513 * If it fails send a RST. This breaks the loop in the
2514 * "LAND" DoS attack, and also prevents an ACK storm
2515 * between two listening ports that have been sent forged
2516 * SYN segments, each with the source address of the other.
2517 */
2518 if (tp->t_state == TCPS_SYN_RECEIVED && (thflags & TH_ACK) &&
2519 (SEQ_GT(tp->snd_una, th->th_ack) ||
2520 SEQ_GT(th->th_ack, tp->snd_max)) ) {
2521 rstreason = BANDLIM_RST_OPENPORT;
2522 goto dropwithreset;
2523 }
2524#ifdef TCPDEBUG
2525 if (so->so_options & SO_DEBUG)
2526 tcp_trace(TA_DROP, ostate, tp, (void *)tcp_saveipgen,
2527 &tcp_savetcp, 0);
2528#endif
2529 m_freem(m);
2530 tp->t_flags |= TF_ACKNOW;
2531 (void) tcp_output(tp);
2532 return;
2533
2534dropwithreset:
2535 /*
2536 * Generate a RST, dropping incoming segment.
2537 * Make ACK acceptable to originator of segment.
2538 * Don't bother to respond if destination was broadcast/multicast.
2539 */
61896e3c 2540 if ((thflags & TH_RST) || m->m_flags & (M_BCAST | M_MCAST))
984263bc
MD
2541 goto drop;
2542 if (isipv6) {
2543 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
2544 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src))
2545 goto drop;
2546 } else {
2547 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) ||
2548 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
95b22adf
JH
2549 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) ||
2550 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif))
984263bc
MD
2551 goto drop;
2552 }
2553 /* IPv6 anycast check is done at tcp6_input() */
2554
2555 /*
2556 * Perform bandwidth limiting.
2557 */
2558#ifdef ICMP_BANDLIM
2559 if (badport_bandlim(rstreason) < 0)
2560 goto drop;
2561#endif
2562
2563#ifdef TCPDEBUG
2564 if (tp == NULL || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
2565 tcp_trace(TA_DROP, ostate, tp, (void *)tcp_saveipgen,
2566 &tcp_savetcp, 0);
2567#endif
2568 if (thflags & TH_ACK)
2569 /* mtod() below is safe as long as hdr dropping is delayed */
2570 tcp_respond(tp, mtod(m, void *), th, m, (tcp_seq)0, th->th_ack,
2571 TH_RST);
2572 else {
2573 if (thflags & TH_SYN)
2574 tlen++;
2575 /* mtod() below is safe as long as hdr dropping is delayed */
61896e3c
JH
2576 tcp_respond(tp, mtod(m, void *), th, m, th->th_seq + tlen,
2577 (tcp_seq)0, TH_RST | TH_ACK);
984263bc
MD
2578 }
2579 return;
2580
2581drop:
2582 /*
2583 * Drop space held by incoming segment and return.
2584 */
2585#ifdef TCPDEBUG
2586 if (tp == NULL || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
2587 tcp_trace(TA_DROP, ostate, tp, (void *)tcp_saveipgen,
2588 &tcp_savetcp, 0);
2589#endif
2590 m_freem(m);
2591 return;
2592}
2593
2594/*
2595 * Parse TCP options and place in tcpopt.
2596 */
2597static void
95b22adf 2598tcp_dooptions(struct tcpopt *to, u_char *cp, int cnt, boolean_t is_syn)
984263bc 2599{
91489f6b 2600 int opt, optlen, i;
984263bc
MD
2601
2602 to->to_flags = 0;
2603 for (; cnt > 0; cnt -= optlen, cp += optlen) {
2604 opt = cp[0];
2605 if (opt == TCPOPT_EOL)
2606 break;
2607 if (opt == TCPOPT_NOP)
2608 optlen = 1;
2609 else {
2610 if (cnt < 2)
2611 break;
2612 optlen = cp[1];
2613 if (optlen < 2 || optlen > cnt)
2614 break;
2615 }
2616 switch (opt) {
2617 case TCPOPT_MAXSEG:
2618 if (optlen != TCPOLEN_MAXSEG)
2619 continue;
2620 if (!is_syn)
2621 continue;
2622 to->to_flags |= TOF_MSS;
95b22adf 2623 bcopy(cp + 2, &to->to_mss, sizeof(to->to_mss));
984263bc
MD
2624 to->to_mss = ntohs(to->to_mss);
2625 break;
2626 case TCPOPT_WINDOW:
2627 if (optlen != TCPOLEN_WINDOW)
2628 continue;
95b22adf 2629 if (!is_syn)
984263bc
MD
2630 continue;
2631 to->to_flags |= TOF_SCALE;
2632 to->to_requested_s_scale = min(cp[2], TCP_MAX_WINSHIFT);
2633 break;
2634 case TCPOPT_TIMESTAMP:
2635 if (optlen != TCPOLEN_TIMESTAMP)
2636 continue;
2637 to->to_flags |= TOF_TS;
95b22adf 2638 bcopy(cp + 2, &to->to_tsval, sizeof(to->to_tsval));
984263bc 2639 to->to_tsval = ntohl(to->to_tsval);
95b22adf 2640 bcopy(cp + 6, &to->to_tsecr, sizeof(to->to_tsecr));
984263bc
MD
2641 to->to_tsecr = ntohl(to->to_tsecr);
2642 break;
2643 case TCPOPT_CC:
2644 if (optlen != TCPOLEN_CC)
2645 continue;
2646 to->to_flags |= TOF_CC;
95b22adf 2647 bcopy(cp + 2, &to->to_cc, sizeof(to->to_cc));
984263bc
MD
2648 to->to_cc = ntohl(to->to_cc);
2649 break;
2650 case TCPOPT_CCNEW:
2651 if (optlen != TCPOLEN_CC)
2652 continue;
2653 if (!is_syn)
2654 continue;
2655 to->to_flags |= TOF_CCNEW;
95b22adf 2656 bcopy(cp + 2, &to->to_cc, sizeof(to->to_cc));
984263bc
MD
2657 to->to_cc = ntohl(to->to_cc);
2658 break;
2659 case TCPOPT_CCECHO:
2660 if (optlen != TCPOLEN_CC)
2661 continue;
2662 if (!is_syn)
2663 continue;
2664 to->to_flags |= TOF_CCECHO;
95b22adf 2665 bcopy(cp + 2, &to->to_ccecho, sizeof(to->to_ccecho));
984263bc
MD
2666 to->to_ccecho = ntohl(to->to_ccecho);
2667 break;
91489f6b
JH
2668 case TCPOPT_SACK_PERMITTED:
2669 if (optlen != TCPOLEN_SACK_PERMITTED)
2670 continue;
2671 if (!is_syn)
2672 continue;
2673 to->to_flags |= TOF_SACK_PERMITTED;
2674 break;
2675 case TCPOPT_SACK:
2676 if ((optlen - 2) & 0x07) /* not multiple of 8 */
2677 continue;
2678 to->to_nsackblocks = (optlen - 2) / 8;
2679 to->to_sackblocks = (struct raw_sackblock *) (cp + 2);
2680 to->to_flags |= TOF_SACK;
2681 for (i = 0; i < to->to_nsackblocks; i++) {
2682 struct raw_sackblock *r = &to->to_sackblocks[i];
2683
2684 r->rblk_start = ntohl(r->rblk_start);
2685 r->rblk_end = ntohl(r->rblk_end);
2686 }
2687 break;
984263bc
MD
2688 default:
2689 continue;
2690 }
2691 }
2692}
2693
2694/*
2695 * Pull out of band byte out of a segment so
2696 * it doesn't appear in the user's data queue.
2697 * It is still reflected in the segment length for
2698 * sequencing purposes.
95b22adf 2699 * "off" is the delayed to be dropped hdrlen.
984263bc
MD
2700 */
2701static void
95b22adf 2702tcp_pulloutofband(struct socket *so, struct tcphdr *th, struct mbuf *m, int off)
984263bc
MD
2703{
2704 int cnt = off + th->th_urp - 1;
2705
2706 while (cnt >= 0) {
2707 if (m->m_len > cnt) {
2708 char *cp = mtod(m, caddr_t) + cnt;
2709 struct tcpcb *tp = sototcpcb(so);
2710
2711 tp->t_iobc = *cp;
2712 tp->t_oobflags |= TCPOOB_HAVEDATA;
95b22adf 2713 bcopy(cp + 1, cp, m->m_len - cnt - 1);
984263bc
MD
2714 m->m_len--;
2715 if (m->m_flags & M_PKTHDR)
2716 m->m_pkthdr.len--;
2717 return;
2718 }
2719 cnt -= m->m_len;
2720 m = m->m_next;
2721 if (m == 0)
2722 break;
2723 }
2724 panic("tcp_pulloutofband");
2725}
2726
2727/*
2728 * Collect new round-trip time estimate
2729 * and update averages and current timeout.
2730 */
2731static void
95b22adf 2732tcp_xmit_timer(struct tcpcb *tp, int rtt)
984263bc 2733{
2256ba69 2734 int delta;
984263bc
MD
2735
2736 tcpstat.tcps_rttupdated++;
2737 tp->t_rttupdated++;
2738 if (tp->t_srtt != 0) {
2739 /*
2740 * srtt is stored as fixed point with 5 bits after the
2741 * binary point (i.e., scaled by 8). The following magic
2742 * is equivalent to the smoothing algorithm in rfc793 with
2743 * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed
2744 * point). Adjust rtt to origin 0.
2745 */
2746 delta = ((rtt - 1) << TCP_DELTA_SHIFT)
2747 - (tp->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT));
2748
2749 if ((tp->t_srtt += delta) <= 0)
2750 tp->t_srtt = 1;
2751
2752 /*
2753 * We accumulate a smoothed rtt variance (actually, a
2754 * smoothed mean difference), then set the retransmit
2755 * timer to smoothed rtt + 4 times the smoothed variance.
2756 * rttvar is stored as fixed point with 4 bits after the
2757 * binary point (scaled by 16). The following is
2758 * equivalent to rfc793 smoothing with an alpha of .75
2759 * (rttvar = rttvar*3/4 + |delta| / 4). This replaces
2760 * rfc793's wired-in beta.
2761 */
2762 if (delta < 0)
2763 delta = -delta;
2764 delta -= tp->t_rttvar >> (TCP_RTTVAR_SHIFT - TCP_DELTA_SHIFT);
2765 if ((tp->t_rttvar += delta) <= 0)
2766 tp->t_rttvar = 1;
2767 if (tp->t_rttbest > tp->t_srtt + tp->t_rttvar)
2768 tp->t_rttbest = tp->t_srtt + tp->t_rttvar;
2769 } else {
2770 /*
2771 * No rtt measurement yet - use the unsmoothed rtt.
2772 * Set the variance to half the rtt (so our first
2773 * retransmit happens at 3*rtt).
2774 */
2775 tp->t_srtt = rtt << TCP_RTT_SHIFT;
2776 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1);
2777 tp->t_rttbest = tp->t_srtt + tp->t_rttvar;
2778 }
2779 tp->t_rtttime = 0;
2780 tp->t_rxtshift = 0;
2781
2782 /*
2783 * the retransmit should happen at rtt + 4 * rttvar.
2784 * Because of the way we do the smoothing, srtt and rttvar
2785 * will each average +1/2 tick of bias. When we compute
2786 * the retransmit timer, we want 1/2 tick of rounding and
2787 * 1 extra tick because of +-1/2 tick uncertainty in the
2788 * firing of the timer. The bias will give us exactly the
2789 * 1.5 tick we need. But, because the bias is
2790 * statistical, we have to test that we don't drop below
2791 * the minimum feasible timer (which is 2 ticks).
2792 */
2793 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp),
2794 max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX);
2795
2796 /*
2797 * We received an ack for a packet that wasn't retransmitted;
2798 * it is probably safe to discard any error indications we've
2799 * received recently. This isn't quite right, but close enough
2800 * for now (a route might have failed after we sent a segment,
2801 * and the return path might not be symmetrical).
2802 */
2803 tp->t_softerror = 0;
2804}
2805
2806/*
2807 * Determine a reasonable value for maxseg size.
2808 * If the route is known, check route for mtu.
2809 * If none, use an mss that can be handled on the outgoing
2810 * interface without forcing IP to fragment; if bigger than
2811 * an mbuf cluster (MCLBYTES), round down to nearest multiple of MCLBYTES
2812 * to utilize large mbufs. If no route is found, route has no mtu,
2813 * or the destination isn't local, use a default, hopefully conservative
2814 * size (usually 512 or the default IP max size, but no more than the mtu
2815 * of the interface), as we can't discover anything about intervening
2816 * gateways or networks. We also initialize the congestion/slow start
2817 * window to be a single segment if the destination isn't local.
2818 * While looking at the routing entry, we also initialize other path-dependent
2819 * parameters from pre-set or cached values in the routing entry.
2820 *
2821 * Also take into account the space needed for options that we
2822 * send regularly. Make maxseg shorter by that amount to assure
2823 * that we can send maxseg amount of data even when the options
2824 * are present. Store the upper limit of the length of options plus
2825 * data in maxopd.
2826 *
2827 * NOTE that this routine is only called when we process an incoming
2828 * segment, for outgoing segments only tcp_mssopt is called.
2829 *
2830 * In case of T/TCP, we call this routine during implicit connection
2831 * setup as well (offer = -1), to initialize maxseg from the cached
2832 * MSS of our peer.
2833 */
2834void
95b22adf 2835tcp_mss(struct tcpcb *tp, int offer)
984263bc 2836{
2256ba69 2837 struct rtentry *rt;
984263bc 2838 struct ifnet *ifp;
2256ba69 2839 int rtt, mss;
984263bc
MD
2840 u_long bufsize;
2841 struct inpcb *inp = tp->t_inpcb;
2842 struct socket *so;
2843 struct rmxp_tao *taop;
2844 int origoffer = offer;
2845#ifdef INET6
d24ce1dc 2846 boolean_t isipv6 = ((inp->inp_vflag & INP_IPV6) ? TRUE : FALSE);
984263bc
MD
2847 size_t min_protoh = isipv6 ?
2848 sizeof(struct ip6_hdr) + sizeof(struct tcphdr) :
2849 sizeof(struct tcpiphdr);
2850#else
d24ce1dc 2851 const boolean_t isipv6 = FALSE;
984263bc
MD
2852 const size_t min_protoh = sizeof(struct tcpiphdr);
2853#endif
2854
2855 if (isipv6)
2856 rt = tcp_rtlookup6(&inp->inp_inc);
2857 else
2858 rt = tcp_rtlookup(&inp->inp_inc);
2859 if (rt == NULL) {
2860 tp->t_maxopd = tp->t_maxseg =
d24ce1dc 2861 (isipv6 ? tcp_v6mssdflt : tcp_mssdflt);
984263bc
MD
2862 return;
2863 }
2864 ifp = rt->rt_ifp;
2865 so = inp->inp_socket;
2866
2867 taop = rmx_taop(rt->rt_rmx);
2868 /*
2869 * Offer == -1 means that we didn't receive SYN yet,
2870 * use cached value in that case;
2871 */
2872 if (offer == -1)
2873 offer = taop->tao_mssopt;
2874 /*
2875 * Offer == 0 means that there was no MSS on the SYN segment,
2876 * in this case we use tcp_mssdflt.
2877 */
2878 if (offer == 0)
d24ce1dc 2879 offer = (isipv6 ? tcp_v6mssdflt : tcp_mssdflt);
984263bc
MD
2880 else
2881 /*
2882 * Sanity check: make sure that maxopd will be large
2883 * enough to allow some data on segments even is the
2884 * all the option space is used (40bytes). Otherwise
2885 * funny things may happen in tcp_output.
2886 */
2887 offer = max(offer, 64);
2888 taop->tao_mssopt = offer;
2889
2890 /*
2891 * While we're here, check if there's an initial rtt
2892 * or rttvar. Convert from the route-table units
2893 * to scaled multiples of the slow timeout timer.
2894 */
2895 if (tp->t_srtt == 0 && (rtt = rt->rt_rmx.rmx_rtt)) {
2896 /*
2897 * XXX the lock bit for RTT indicates that the value
2898 * is also a minimum value; this is subject to time.
2899 */
2900 if (rt->rt_rmx.rmx_locks & RTV_RTT)
2901 tp->t_rttmin = rtt / (RTM_RTTUNIT / hz);
2902 tp->t_srtt = rtt / (RTM_RTTUNIT / (hz * TCP_RTT_SCALE));
2903 tp->t_rttbest = tp->t_srtt + TCP_RTT_SCALE;
2904 tcpstat.tcps_usedrtt++;
2905 if (rt->rt_rmx.rmx_rttvar) {
2906 tp->t_rttvar = rt->rt_rmx.rmx_rttvar /
2907 (RTM_RTTUNIT / (hz * TCP_RTTVAR_SCALE));
2908 tcpstat.tcps_usedrttvar++;
2909 } else {
2910 /* default variation is +- 1 rtt */
2911 tp->t_rttvar =
2912 tp->t_srtt * TCP_RTTVAR_SCALE / TCP_RTT_SCALE;
2913 }
2914 TCPT_RANGESET(tp->t_rxtcur,
2915 ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1,
2916 tp->t_rttmin, TCPTV_REXMTMAX);
2917 }
2918 /*
2919 * if there's an mtu associated with the route, use it
2920 * else, use the link mtu.
2921 */
2922 if (rt->rt_rmx.rmx_mtu)
2923 mss = rt->rt_rmx.rmx_mtu - min_protoh;
2924 else {
2925 if (isipv6) {
2926 mss = nd_ifinfo[rt->rt_ifp->if_index].linkmtu -
2927 min_protoh;
2928 if (!in6_localaddr(&inp->in6p_faddr))
2929 mss = min(mss, tcp_v6mssdflt);
2930 } else {
2931 mss = ifp->if_mtu - min_protoh;
2932 if (!in_localaddr(inp->inp_faddr))
2933 mss = min(mss, tcp_mssdflt);
2934 }
2935 }
2936 mss = min(mss, offer);
2937 /*
2938 * maxopd stores the maximum length of data AND options
2939 * in a segment; maxseg is the amount of data in a normal
2940 * segment. We need to store this value (maxopd) apart
2941 * from maxseg, because now every segment carries options
2942 * and thus we normally have somewhat less data in segments.
2943 */
2944 tp->t_maxopd = mss;
2945
2946 /*
2947 * In case of T/TCP, origoffer==-1 indicates, that no segments
2948 * were received yet. In this case we just guess, otherwise
2949 * we do the same as before T/TCP.
2950 */
61896e3c 2951 if ((tp->t_flags & (TF_REQ_TSTMP | TF_NOOPT)) == TF_REQ_TSTMP &&
984263bc
MD
2952 (origoffer == -1 ||
2953 (tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP))
2954 mss -= TCPOLEN_TSTAMP_APPA;
61896e3c 2955 if ((tp->t_flags & (TF_REQ_CC | TF_NOOPT)) == TF_REQ_CC &&
984263bc
MD
2956 (origoffer == -1 ||
2957 (tp->t_flags & TF_RCVD_CC) == TF_RCVD_CC))
2958 mss -= TCPOLEN_CC_APPA;
2959
2960#if (MCLBYTES & (MCLBYTES - 1)) == 0
2961 if (mss > MCLBYTES)
2962 mss &= ~(MCLBYTES-1);
2963#else
2964 if (mss > MCLBYTES)
2965 mss = mss / MCLBYTES * MCLBYTES;
2966#endif
2967 /*
2968 * If there's a pipesize, change the socket buffer
2969 * to that size. Make the socket buffers an integral
2970 * number of mss units; if the mss is larger than
2971 * the socket buffer, decrease the mss.
2972 */
2973#ifdef RTV_SPIPE
2974 if ((bufsize = rt->rt_rmx.rmx_sendpipe) == 0)
2975#endif
2976 bufsize = so->so_snd.sb_hiwat;
2977 if (bufsize < mss)
2978 mss = bufsize;
2979 else {
2980 bufsize = roundup(bufsize, mss);
2981 if (bufsize > sb_max)
2982 bufsize = sb_max;
2983 if (bufsize > so->so_snd.sb_hiwat)
2984 (void)sbreserve(&so->so_snd, bufsize, so, NULL);
2985 }
2986 tp->t_maxseg = mss;
2987
2988#ifdef RTV_RPIPE
2989 if ((bufsize = rt->rt_rmx.rmx_recvpipe) == 0)
2990#endif
2991 bufsize = so->so_rcv.sb_hiwat;
2992 if (bufsize > mss) {
2993 bufsize = roundup(bufsize, mss);
2994 if (bufsize > sb_max)
2995 bufsize = sb_max;
2996 if (bufsize > so->so_rcv.sb_hiwat)
2997 (void)sbreserve(&so->so_rcv, bufsize, so, NULL);
2998 }
2999
3000 /*
3001 * Set the slow-start flight size depending on whether this
3002 * is a local network or not.
3003 */
4b52d5ee
JH
3004 if (tcp_do_rfc3390)
3005 tp->snd_cwnd = min(4 * mss, max(2 * mss, 4380));
3006 else if ((isipv6 && in6_localaddr(&inp->in6p_faddr)) ||
3007 (!isipv6 && in_localaddr(inp->inp_faddr)))
984263bc 3008 tp->snd_cwnd = mss * ss_fltsz_local;
4b52d5ee 3009 else
984263bc
MD
3010 tp->snd_cwnd = mss * ss_fltsz;
3011
3012 if (rt->rt_rmx.rmx_ssthresh) {
3013 /*
3014 * There's some sort of gateway or interface
3015 * buffer limit on the path. Use this to set
3016 * the slow start threshhold, but set the
3017 * threshold to no less than 2*mss.
3018 */
3019 tp->snd_ssthresh = max(2 * mss, rt->rt_rmx.rmx_ssthresh);
3020 tcpstat.tcps_usedssthresh++;
3021 }
3022}
3023
3024/*
3025 * Determine the MSS option to send on an outgoing SYN.
3026 */
3027int
95b22adf 3028tcp_mssopt(struct tcpcb *tp)
984263bc
MD
3029{
3030 struct rtentry *rt;
3031#ifdef INET6
d24ce1dc
JH
3032 boolean_t isipv6 =
3033 ((tp->t_inpcb->inp_vflag & INP_IPV6) ? TRUE : FALSE);
984263bc
MD
3034 int min_protoh = isipv6 ?
3035 sizeof(struct ip6_hdr) + sizeof(struct tcphdr) :
3036 sizeof(struct tcpiphdr);
3037#else
d24ce1dc 3038 const boolean_t isipv6 = FALSE;
984263bc
MD
3039 const size_t min_protoh = sizeof(struct tcpiphdr);
3040#endif
3041
3042 if (isipv6)
3043 rt = tcp_rtlookup6(&tp->t_inpcb->inp_inc);
3044 else
3045 rt = tcp_rtlookup(&tp->t_inpcb->inp_inc);
3046 if (rt == NULL)
3047 return (isipv6 ? tcp_v6mssdflt : tcp_mssdflt);
3048
3049 return (rt->rt_ifp->if_mtu - min_protoh);
3050}
3051
984263bc
MD
3052/*
3053 * When a partial ack arrives, force the retransmission of the
91489f6b
JH
3054 * next unacknowledged segment. Do not exit Fast Recovery.
3055 *
3056 * Implement the Slow-but-Steady variant of NewReno by restarting the
3057 * the retransmission timer. Turn it off here so it can be restarted
3058 * later in tcp_output().
984263bc
MD
3059 */
3060static void
91489f6b 3061tcp_newreno_partial_ack(struct tcpcb *tp, struct tcphdr *th, int acked)
984263bc 3062{
91489f6b
JH
3063 tcp_seq old_snd_nxt = tp->snd_nxt;
3064 u_long ocwnd = tp->snd_cwnd;
984263bc
MD
3065
3066 callout_stop(tp->tt_rexmt);
3067 tp->t_rtttime = 0;
3068 tp->snd_nxt = th->th_ack;
91489f6b
JH
3069 /* Set snd_cwnd to one segment beyond acknowledged offset. */
3070 tp->snd_cwnd = tp->t_maxseg;
984263bc
MD
3071 tp->t_flags |= TF_ACKNOW;
3072 (void) tcp_output(tp);
91489f6b
JH
3073 if (SEQ_GT(old_snd_nxt, tp->snd_nxt))
3074 tp->snd_nxt = old_snd_nxt;
3075 /* partial window deflation */
3076 tp->snd_cwnd = ocwnd - acked + tp->t_maxseg;
3077}
3078
3079/*
3080 * In contrast to the Slow-but-Steady NewReno variant,
3081 * we do not reset the retransmission timer for SACK retransmissions,
3082 * except when retransmitting snd_una.
3083 */
3084static void
3085tcp_sack_rexmt(struct tcpcb *tp, struct tcphdr *th)
3086{
3087 uint32_t pipe, seglen;
3088 tcp_seq nextrexmt;
3089 boolean_t lostdup;
3090 tcp_seq old_snd_nxt = tp->snd_nxt;
3091 u_long ocwnd = tp->snd_cwnd;
3092 int nseg = 0; /* consecutive new segments */
3093#define MAXBURST 4 /* limit burst of new packets on partial ack */
3094
3095 tp->t_rtttime = 0;
3096 pipe = tcp_sack_compute_pipe(tp);
3097 while ((tcp_seq_diff_t)(ocwnd - pipe) >= (tcp_seq_diff_t)tp->t_maxseg &&
3098 (!tcp_do_smartsack || nseg < MAXBURST) &&
3099 tcp_sack_nextseg(tp, &nextrexmt, &seglen, &lostdup)) {
3100 uint32_t sent;
3101 tcp_seq old_snd_max;
3102 int error;
3103
3104 if (nextrexmt == tp->snd_max) ++nseg;
3105 tp->snd_nxt = nextrexmt;
3106 tp->snd_cwnd = nextrexmt - tp->snd_una + seglen;
3107 old_snd_max = tp->snd_max;
3108 if (nextrexmt == tp->snd_una)
3109 callout_stop(tp->tt_rexmt);
3110 error = tcp_output(tp);
3111 if (error != 0)
3112 break;
3113 sent = tp->snd_nxt - nextrexmt;
3114 if (sent <= 0)
3115 break;
3116 if (!lostdup)
3117 pipe += sent;
3118 tcpstat.tcps_sndsackpack++;
3119 tcpstat.tcps_sndsackbyte += sent;
3120 if (SEQ_LT(nextrexmt, old_snd_max) &&
3121 SEQ_LT(tp->rexmt_high, tp->snd_nxt))
3122 tp->rexmt_high = seq_min(tp->snd_nxt, old_snd_max);
3123 }
3124 if (SEQ_GT(old_snd_nxt, tp->snd_nxt))
3125 tp->snd_nxt = old_snd_nxt;
984263bc 3126 tp->snd_cwnd = ocwnd;
984263bc 3127}