tcp/ncr: Avoid using magic number
[dragonfly.git] / sys / netinet / tcp_input.c
CommitLineData
984263bc 1/*
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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 *
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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/*
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35 * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995
36 * The Regents of the University of California. All rights reserved.
37 *
38 * Redistribution and use in source and binary forms, with or without
39 * modification, are permitted provided that the following conditions
40 * are met:
41 * 1. Redistributions of source code must retain the above copyright
42 * notice, this list of conditions and the following disclaimer.
43 * 2. Redistributions in binary form must reproduce the above copyright
44 * notice, this list of conditions and the following disclaimer in the
45 * documentation and/or other materials provided with the distribution.
46 * 3. All advertising materials mentioning features or use of this software
47 * must display the following acknowledgement:
48 * This product includes software developed by the University of
49 * California, Berkeley and its contributors.
50 * 4. Neither the name of the University nor the names of its contributors
51 * may be used to endorse or promote products derived from this software
52 * without specific prior written permission.
53 *
54 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
55 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
56 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
57 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
58 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
59 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
60 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
61 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
62 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
63 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
64 * SUCH DAMAGE.
65 *
66 * @(#)tcp_input.c 8.12 (Berkeley) 5/24/95
67 * $FreeBSD: src/sys/netinet/tcp_input.c,v 1.107.2.38 2003/05/21 04:46:41 cjc Exp $
68 */
69
b1992928 70#include "opt_inet.h"
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71#include "opt_inet6.h"
72#include "opt_ipsec.h"
73#include "opt_tcpdebug.h"
74#include "opt_tcp_input.h"
75
76#include <sys/param.h>
77#include <sys/systm.h>
78#include <sys/kernel.h>
79#include <sys/sysctl.h>
80#include <sys/malloc.h>
81#include <sys/mbuf.h>
82#include <sys/proc.h> /* for proc0 declaration */
83#include <sys/protosw.h>
84#include <sys/socket.h>
85#include <sys/socketvar.h>
86#include <sys/syslog.h>
3f9db7f8 87#include <sys/in_cksum.h>
984263bc 88
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89#include <sys/socketvar2.h>
90
984263bc 91#include <machine/cpu.h> /* before tcp_seq.h, for tcp_random18() */
a00138cb 92#include <machine/stdarg.h>
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93
94#include <net/if.h>
95#include <net/route.h>
96
97#include <netinet/in.h>
98#include <netinet/in_systm.h>
99#include <netinet/ip.h>
95b22adf 100#include <netinet/ip_icmp.h> /* for ICMP_BANDLIM */
984263bc 101#include <netinet/in_var.h>
95b22adf 102#include <netinet/icmp_var.h> /* for ICMP_BANDLIM */
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103#include <netinet/in_pcb.h>
104#include <netinet/ip_var.h>
105#include <netinet/ip6.h>
106#include <netinet/icmp6.h>
107#include <netinet6/nd6.h>
108#include <netinet6/ip6_var.h>
109#include <netinet6/in6_pcb.h>
110#include <netinet/tcp.h>
111#include <netinet/tcp_fsm.h>
112#include <netinet/tcp_seq.h>
113#include <netinet/tcp_timer.h>
a48c5dd5 114#include <netinet/tcp_timer2.h>
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115#include <netinet/tcp_var.h>
116#include <netinet6/tcp6_var.h>
117#include <netinet/tcpip.h>
95b22adf 118
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119#ifdef TCPDEBUG
120#include <netinet/tcp_debug.h>
121
95b22adf 122u_char tcp_saveipgen[40]; /* the size must be of max ip header, now IPv6 */
984263bc 123struct tcphdr tcp_savetcp;
95b22adf 124#endif
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125
126#ifdef FAST_IPSEC
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127#include <netproto/ipsec/ipsec.h>
128#include <netproto/ipsec/ipsec6.h>
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129#endif
130
131#ifdef IPSEC
132#include <netinet6/ipsec.h>
133#include <netinet6/ipsec6.h>
d2438d69 134#include <netproto/key/key.h>
95b22adf 135#endif
984263bc 136
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137MALLOC_DEFINE(M_TSEGQ, "tseg_qent", "TCP segment queue entry");
138
984263bc 139static int log_in_vain = 0;
d24ce1dc 140SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_in_vain, CTLFLAG_RW,
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141 &log_in_vain, 0, "Log all incoming TCP connections");
142
143static int blackhole = 0;
144SYSCTL_INT(_net_inet_tcp, OID_AUTO, blackhole, CTLFLAG_RW,
145 &blackhole, 0, "Do not send RST when dropping refused connections");
146
147int tcp_delack_enabled = 1;
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148SYSCTL_INT(_net_inet_tcp, OID_AUTO, delayed_ack, CTLFLAG_RW,
149 &tcp_delack_enabled, 0,
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150 "Delay ACK to try and piggyback it onto a data packet");
151
152#ifdef TCP_DROP_SYNFIN
153static int drop_synfin = 0;
154SYSCTL_INT(_net_inet_tcp, OID_AUTO, drop_synfin, CTLFLAG_RW,
155 &drop_synfin, 0, "Drop TCP packets with SYN+FIN set");
156#endif
157
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158static int tcp_do_limitedtransmit = 1;
159SYSCTL_INT(_net_inet_tcp, OID_AUTO, limitedtransmit, CTLFLAG_RW,
160 &tcp_do_limitedtransmit, 0, "Enable RFC 3042 (Limited Transmit)");
161
91489f6b 162static int tcp_do_early_retransmit = 1;
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163SYSCTL_INT(_net_inet_tcp, OID_AUTO, earlyretransmit, CTLFLAG_RW,
164 &tcp_do_early_retransmit, 0, "Early retransmit");
165
8acdb67c 166int tcp_aggregate_acks = 1;
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167SYSCTL_INT(_net_inet_tcp, OID_AUTO, aggregate_acks, CTLFLAG_RW,
168 &tcp_aggregate_acks, 0, "Aggregate built-up acks into one ack");
169
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170static int tcp_do_eifel_detect = 1;
171SYSCTL_INT(_net_inet_tcp, OID_AUTO, eifel, CTLFLAG_RW,
172 &tcp_do_eifel_detect, 0, "Eifel detection algorithm (RFC 3522)");
173
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174static int tcp_do_abc = 1;
175SYSCTL_INT(_net_inet_tcp, OID_AUTO, abc, CTLFLAG_RW,
176 &tcp_do_abc, 0,
177 "TCP Appropriate Byte Counting (RFC 3465)");
178
91489f6b 179/*
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180 * The following value actually takes range [25ms, 250ms],
181 * given that most modern systems use 1ms ~ 10ms as the unit
182 * of timestamp option.
183 */
184static u_int tcp_paws_tolerance = 25;
185SYSCTL_UINT(_net_inet_tcp, OID_AUTO, paws_tolerance, CTLFLAG_RW,
186 &tcp_paws_tolerance, 0, "RFC1323 PAWS tolerance");
187
188/*
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189 * Define as tunable for easy testing with SACK on and off.
190 * Warning: do not change setting in the middle of an existing active TCP flow,
191 * else strange things might happen to that flow.
192 */
6e5bbdda 193int tcp_do_sack = 1;
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194SYSCTL_INT(_net_inet_tcp, OID_AUTO, sack, CTLFLAG_RW,
195 &tcp_do_sack, 0, "Enable SACK Algorithms");
196
197int tcp_do_smartsack = 1;
198SYSCTL_INT(_net_inet_tcp, OID_AUTO, smartsack, CTLFLAG_RW,
199 &tcp_do_smartsack, 0, "Enable Smart SACK Algorithms");
200
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201int tcp_do_rescuesack = 1;
202SYSCTL_INT(_net_inet_tcp, OID_AUTO, rescuesack, CTLFLAG_RW,
203 &tcp_do_rescuesack, 0, "Rescue retransmission for SACK");
204
c01f968f 205int tcp_aggressive_rescuesack = 0;
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206SYSCTL_INT(_net_inet_tcp, OID_AUTO, rescuesack_agg, CTLFLAG_RW,
207 &tcp_aggressive_rescuesack, 0, "Aggressive rescue retransmission for SACK");
208
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209static int tcp_force_sackrxt = 1;
210SYSCTL_INT(_net_inet_tcp, OID_AUTO, force_sackrxt, CTLFLAG_RW,
211 &tcp_force_sackrxt, 0, "Allowed forced SACK retransmit burst");
212
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213int tcp_do_rfc6675 = 1;
214SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc6675, CTLFLAG_RW,
215 &tcp_do_rfc6675, 0, "Enable RFC6675");
ffe35e17 216
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217int tcp_rfc6675_rxt = 0;
218SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc6675_rxt, CTLFLAG_RW,
219 &tcp_rfc6675_rxt, 0, "Enable RFC6675 retransmit");
5fd89c20 220
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221SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass, CTLFLAG_RW, 0,
222 "TCP Segment Reassembly Queue");
223
224int tcp_reass_maxseg = 0;
225SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RD,
226 &tcp_reass_maxseg, 0,
227 "Global maximum number of TCP Segments in Reassembly Queue");
228
229int tcp_reass_qsize = 0;
230SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, cursegments, CTLFLAG_RD,
231 &tcp_reass_qsize, 0,
232 "Global number of TCP Segments currently in Reassembly Queue");
233
234static int tcp_reass_overflows = 0;
235SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, overflows, CTLFLAG_RD,
236 &tcp_reass_overflows, 0,
237 "Global number of TCP Segment Reassembly Queue Overflows");
238
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239int tcp_do_autorcvbuf = 1;
240SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_auto, CTLFLAG_RW,
241 &tcp_do_autorcvbuf, 0, "Enable automatic receive buffer sizing");
242
243int tcp_autorcvbuf_inc = 16*1024;
244SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_inc, CTLFLAG_RW,
245 &tcp_autorcvbuf_inc, 0,
246 "Incrementor step size of automatic receive buffer");
247
46e92930 248int tcp_autorcvbuf_max = 2*1024*1024;
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249SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_max, CTLFLAG_RW,
250 &tcp_autorcvbuf_max, 0, "Max size of automatic receive buffer");
251
b3f79714 252int tcp_sosend_agglim = 3;
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253SYSCTL_INT(_net_inet_tcp, OID_AUTO, sosend_agglim, CTLFLAG_RW,
254 &tcp_sosend_agglim, 0, "TCP sosend mbuf aggregation limit");
5b0b9fa5 255
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256int tcp_sosend_async = 1;
257SYSCTL_INT(_net_inet_tcp, OID_AUTO, sosend_async, CTLFLAG_RW,
258 &tcp_sosend_async, 0, "TCP asynchronized pru_send");
f2a3782e 259
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260static int tcp_ignore_redun_dsack = 1;
261SYSCTL_INT(_net_inet_tcp, OID_AUTO, ignore_redun_dsack, CTLFLAG_RW,
262 &tcp_ignore_redun_dsack, 0, "Ignore redundant DSACK");
263
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264static void tcp_dooptions(struct tcpopt *, u_char *, int, boolean_t,
265 tcp_seq);
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266static void tcp_pulloutofband(struct socket *,
267 struct tcphdr *, struct mbuf *, int);
268static int tcp_reass(struct tcpcb *, struct tcphdr *, int *,
269 struct mbuf *);
073ec6c4 270static void tcp_xmit_timer(struct tcpcb *, int, tcp_seq);
91489f6b 271static void tcp_newreno_partial_ack(struct tcpcb *, struct tcphdr *, int);
ccb518ea 272static void tcp_sack_rexmt(struct tcpcb *, boolean_t);
ffe35e17 273static boolean_t tcp_sack_limitedxmit(struct tcpcb *);
01d3427a 274static int tcp_rmx_msl(const struct tcpcb *);
8651f7f8 275static void tcp_established(struct tcpcb *);
0a832381 276static boolean_t tcp_recv_dupack(struct tcpcb *, tcp_seq, u_int);
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277
278/* Neighbor Discovery, Neighbor Unreachability Detection Upper layer hint. */
279#ifdef INET6
280#define ND6_HINT(tp) \
281do { \
282 if ((tp) && (tp)->t_inpcb && \
61896e3c 283 ((tp)->t_inpcb->inp_vflag & INP_IPV6) && \
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284 (tp)->t_inpcb->in6p_route.ro_rt) \
285 nd6_nud_hint((tp)->t_inpcb->in6p_route.ro_rt, NULL, 0); \
286} while (0)
287#else
288#define ND6_HINT(tp)
289#endif
290
291/*
292 * Indicate whether this ack should be delayed. We can delay the ack if
293 * - delayed acks are enabled and
294 * - there is no delayed ack timer in progress and
295 * - our last ack wasn't a 0-sized window. We never want to delay
296 * the ack that opens up a 0-sized window.
297 */
298#define DELAY_ACK(tp) \
a48c5dd5 299 (tcp_delack_enabled && !tcp_callout_pending(tp, tp->tt_delack) && \
61896e3c 300 !(tp->t_flags & TF_RXWIN0SENT))
984263bc 301
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302#define acceptable_window_update(tp, th, tiwin) \
303 (SEQ_LT(tp->snd_wl1, th->th_seq) || \
304 (tp->snd_wl1 == th->th_seq && \
305 (SEQ_LT(tp->snd_wl2, th->th_ack) || \
306 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))
307
ffe35e17
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308#define iceildiv(n, d) (((n)+(d)-1) / (d))
309#define need_early_retransmit(tp, ownd) \
310 (tcp_do_early_retransmit && \
311 (tcp_do_eifel_detect && (tp->t_flags & TF_RCVD_TSTMP)) && \
4c0f4a00 312 ownd < ((tp->t_rxtthresh + 1) * tp->t_maxseg) && \
ffe35e17
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313 tp->t_dupacks + 1 >= iceildiv(ownd, tp->t_maxseg) && \
314 (!TCP_DO_SACK(tp) || ownd <= tp->t_maxseg || \
315 tcp_sack_has_sacked(&tp->scb, ownd - tp->t_maxseg)))
316
9de1f696
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317/*
318 * Returns TRUE, if this segment can be merged with the last
319 * pending segment in the reassemble queue and this segment
320 * does not overlap with the pending segment immediately
321 * preceeding the last pending segment.
322 */
323static __inline boolean_t
324tcp_paws_canreasslast(const struct tcpcb *tp, const struct tcphdr *th, int tlen)
325{
326 const struct tseg_qent *last, *prev;
327
328 last = TAILQ_LAST(&tp->t_segq, tsegqe_head);
329 if (last == NULL)
330 return FALSE;
331
332 /* This segment comes immediately after the last pending segment */
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333 if (last->tqe_th->th_seq + last->tqe_len == th->th_seq) {
334 if (last->tqe_th->th_flags & TH_FIN) {
335 /* No segments should follow segment w/ FIN */
336 return FALSE;
337 }
9de1f696 338 return TRUE;
04e6f08e 339 }
9de1f696
SZ
340
341 if (th->th_seq + tlen != last->tqe_th->th_seq)
342 return FALSE;
343 /* This segment comes immediately before the last pending segment */
344
345 prev = TAILQ_PREV(last, tsegqe_head, tqe_q);
346 if (prev == NULL) {
347 /*
348 * No pending preceeding segment, we assume this segment
349 * could be reassembled.
350 */
351 return TRUE;
352 }
353
354 /* This segment does not overlap with the preceeding segment */
355 if (SEQ_GEQ(th->th_seq, prev->tqe_th->th_seq + prev->tqe_len))
356 return TRUE;
357
358 return FALSE;
359}
360
e2289e66
SZ
361static __inline void
362tcp_ncr_update_rxtthresh(struct tcpcb *tp)
363{
364 int old_rxtthresh = tp->t_rxtthresh;
365 uint32_t ownd = tp->snd_max - tp->snd_una;
366
0983a903 367 tp->t_rxtthresh = max(tcprexmtthresh, ((ownd / tp->t_maxseg) >> 1));
e2289e66
SZ
368 if (tp->t_rxtthresh != old_rxtthresh) {
369 tcp_sack_update_lostseq(&tp->scb, tp->snd_una,
370 tp->t_maxseg, tp->t_rxtthresh);
371 }
372}
373
984263bc 374static int
95b22adf 375tcp_reass(struct tcpcb *tp, struct tcphdr *th, int *tlenp, struct mbuf *m)
984263bc
MD
376{
377 struct tseg_qent *q;
378 struct tseg_qent *p = NULL;
984263bc
MD
379 struct tseg_qent *te;
380 struct socket *so = tp->t_inpcb->inp_socket;
381 int flags;
382
383 /*
61896e3c 384 * Call with th == NULL after become established to
984263bc
MD
385 * force pre-ESTABLISHED data up to user socket.
386 */
61896e3c 387 if (th == NULL)
984263bc
MD
388 goto present;
389
3edf7c37
RG
390 /*
391 * Limit the number of segments in the reassembly queue to prevent
392 * holding on to too many segments (and thus running out of mbufs).
393 * Make sure to let the missing segment through which caused this
394 * queue. Always keep one global queue entry spare to be able to
395 * process the missing segment.
396 */
397 if (th->th_seq != tp->rcv_nxt &&
398 tcp_reass_qsize + 1 >= tcp_reass_maxseg) {
399 tcp_reass_overflows++;
400 tcpstat.tcps_rcvmemdrop++;
401 m_freem(m);
91489f6b
JH
402 /* no SACK block to report */
403 tp->reportblk.rblk_start = tp->reportblk.rblk_end;
3edf7c37
RG
404 return (0);
405 }
406
ba4e3dbe 407 /* Allocate a new queue entry. */
884717e1 408 te = kmalloc(sizeof(struct tseg_qent), M_TSEGQ, M_INTWAIT | M_NULLOK);
984263bc
MD
409 if (te == NULL) {
410 tcpstat.tcps_rcvmemdrop++;
411 m_freem(m);
91489f6b
JH
412 /* no SACK block to report */
413 tp->reportblk.rblk_start = tp->reportblk.rblk_end;
984263bc
MD
414 return (0);
415 }
2d23a8be 416 atomic_add_int(&tcp_reass_qsize, 1);
984263bc 417
942d88ef
SZ
418 if (th->th_flags & TH_FIN)
419 tp->t_flags |= TF_QUEDFIN;
420
984263bc
MD
421 /*
422 * Find a segment which begins after this one does.
423 */
0f9e45de 424 TAILQ_FOREACH(q, &tp->t_segq, tqe_q) {
984263bc
MD
425 if (SEQ_GT(q->tqe_th->th_seq, th->th_seq))
426 break;
427 p = q;
428 }
429
430 /*
431 * If there is a preceding segment, it may provide some of
432 * our data already. If so, drop the data from the incoming
433 * segment. If it provides all of our data, drop us.
434 */
435 if (p != NULL) {
76cf5e41 436 tcp_seq_diff_t i;
91489f6b 437
984263bc
MD
438 /* conversion to int (in i) handles seq wraparound */
439 i = p->tqe_th->th_seq + p->tqe_len - th->th_seq;
91489f6b 440 if (i > 0) { /* overlaps preceding segment */
c7e6499a
SZ
441 tp->sack_flags |=
442 (TSACK_F_DUPSEG | TSACK_F_ENCLOSESEG);
91489f6b
JH
443 /* enclosing block starts w/ preceding segment */
444 tp->encloseblk.rblk_start = p->tqe_th->th_seq;
984263bc 445 if (i >= *tlenp) {
53432bee
SZ
446 if (th->th_flags & TH_FIN)
447 p->tqe_th->th_flags |= TH_FIN;
448
91489f6b 449 /* preceding encloses incoming segment */
3a5d999b
SZ
450 tp->encloseblk.rblk_end = TCP_SACK_BLKEND(
451 p->tqe_th->th_seq + p->tqe_len,
452 p->tqe_th->th_flags);
984263bc
MD
453 tcpstat.tcps_rcvduppack++;
454 tcpstat.tcps_rcvdupbyte += *tlenp;
455 m_freem(m);
efda3bd0 456 kfree(te, M_TSEGQ);
2d23a8be 457 atomic_add_int(&tcp_reass_qsize, -1);
984263bc
MD
458 /*
459 * Try to present any queued data
460 * at the left window edge to the user.
461 * This is needed after the 3-WHS
462 * completes.
463 */
464 goto present; /* ??? */
465 }
466 m_adj(m, i);
467 *tlenp -= i;
468 th->th_seq += i;
91489f6b 469 /* incoming segment end is enclosing block end */
3a5d999b
SZ
470 tp->encloseblk.rblk_end = TCP_SACK_BLKEND(
471 th->th_seq + *tlenp, th->th_flags);
91489f6b
JH
472 /* trim end of reported D-SACK block */
473 tp->reportblk.rblk_end = th->th_seq;
984263bc
MD
474 }
475 }
476 tcpstat.tcps_rcvoopack++;
477 tcpstat.tcps_rcvoobyte += *tlenp;
478
479 /*
480 * While we overlap succeeding segments trim them or,
481 * if they are completely covered, dequeue them.
482 */
483 while (q) {
76cf5e41 484 tcp_seq_diff_t i = (th->th_seq + *tlenp) - q->tqe_th->th_seq;
91489f6b 485 tcp_seq qend = q->tqe_th->th_seq + q->tqe_len;
3a5d999b 486 tcp_seq qend_sack = TCP_SACK_BLKEND(qend, q->tqe_th->th_flags);
91489f6b
JH
487 struct tseg_qent *nq;
488
984263bc
MD
489 if (i <= 0)
490 break;
c7e6499a
SZ
491 if (!(tp->sack_flags & TSACK_F_DUPSEG)) {
492 /* first time through */
493 tp->sack_flags |= (TSACK_F_DUPSEG | TSACK_F_ENCLOSESEG);
91489f6b
JH
494 tp->encloseblk = tp->reportblk;
495 /* report trailing duplicate D-SACK segment */
496 tp->reportblk.rblk_start = q->tqe_th->th_seq;
497 }
c7e6499a 498 if ((tp->sack_flags & TSACK_F_ENCLOSESEG) &&
3a5d999b 499 SEQ_GT(qend_sack, tp->encloseblk.rblk_end)) {
91489f6b 500 /* extend enclosing block if one exists */
3a5d999b 501 tp->encloseblk.rblk_end = qend_sack;
91489f6b 502 }
984263bc
MD
503 if (i < q->tqe_len) {
504 q->tqe_th->th_seq += i;
505 q->tqe_len -= i;
506 m_adj(q->tqe_m, i);
507 break;
508 }
509
53432bee
SZ
510 if (q->tqe_th->th_flags & TH_FIN)
511 th->th_flags |= TH_FIN;
512
0f9e45de
SZ
513 nq = TAILQ_NEXT(q, tqe_q);
514 TAILQ_REMOVE(&tp->t_segq, q, tqe_q);
984263bc 515 m_freem(q->tqe_m);
efda3bd0 516 kfree(q, M_TSEGQ);
2d23a8be 517 atomic_add_int(&tcp_reass_qsize, -1);
984263bc
MD
518 q = nq;
519 }
520
521 /* Insert the new segment queue entry into place. */
522 te->tqe_m = m;
523 te->tqe_th = th;
524 te->tqe_len = *tlenp;
525
91489f6b
JH
526 /* check if can coalesce with following segment */
527 if (q != NULL && (th->th_seq + *tlenp == q->tqe_th->th_seq)) {
53432bee 528 tcp_seq tend_sack;
91489f6b
JH
529
530 te->tqe_len += q->tqe_len;
a174690a 531 if (q->tqe_th->th_flags & TH_FIN)
f16f8cc3 532 te->tqe_th->th_flags |= TH_FIN;
53432bee
SZ
533 tend_sack = TCP_SACK_BLKEND(te->tqe_th->th_seq + te->tqe_len,
534 te->tqe_th->th_flags);
535
91489f6b 536 m_cat(te->tqe_m, q->tqe_m);
3a5d999b 537 tp->encloseblk.rblk_end = tend_sack;
91489f6b
JH
538 /*
539 * When not reporting a duplicate segment, use
540 * the larger enclosing block as the SACK block.
541 */
c7e6499a 542 if (!(tp->sack_flags & TSACK_F_DUPSEG))
3a5d999b 543 tp->reportblk.rblk_end = tend_sack;
0f9e45de 544 TAILQ_REMOVE(&tp->t_segq, q, tqe_q);
efda3bd0 545 kfree(q, M_TSEGQ);
2d23a8be 546 atomic_add_int(&tcp_reass_qsize, -1);
91489f6b
JH
547 }
548
984263bc 549 if (p == NULL) {
0f9e45de 550 TAILQ_INSERT_HEAD(&tp->t_segq, te, tqe_q);
984263bc 551 } else {
91489f6b
JH
552 /* check if can coalesce with preceding segment */
553 if (p->tqe_th->th_seq + p->tqe_len == th->th_seq) {
53432bee
SZ
554 if (te->tqe_th->th_flags & TH_FIN)
555 p->tqe_th->th_flags |= TH_FIN;
a174690a
JH
556 p->tqe_len += te->tqe_len;
557 m_cat(p->tqe_m, te->tqe_m);
91489f6b
JH
558 tp->encloseblk.rblk_start = p->tqe_th->th_seq;
559 /*
560 * When not reporting a duplicate segment, use
561 * the larger enclosing block as the SACK block.
562 */
c7e6499a 563 if (!(tp->sack_flags & TSACK_F_DUPSEG))
91489f6b 564 tp->reportblk.rblk_start = p->tqe_th->th_seq;
efda3bd0 565 kfree(te, M_TSEGQ);
2d23a8be
MD
566 atomic_add_int(&tcp_reass_qsize, -1);
567 } else {
0f9e45de 568 TAILQ_INSERT_AFTER(&tp->t_segq, p, te, tqe_q);
2d23a8be 569 }
984263bc
MD
570 }
571
572present:
573 /*
574 * Present data to user, advancing rcv_nxt through
575 * completed sequence space.
576 */
577 if (!TCPS_HAVEESTABLISHED(tp->t_state))
578 return (0);
0f9e45de 579 q = TAILQ_FIRST(&tp->t_segq);
61896e3c 580 if (q == NULL || q->tqe_th->th_seq != tp->rcv_nxt)
984263bc 581 return (0);
91489f6b 582 tp->rcv_nxt += q->tqe_len;
c7e6499a 583 if (!(tp->sack_flags & TSACK_F_DUPSEG)) {
91489f6b
JH
584 /* no SACK block to report since ACK advanced */
585 tp->reportblk.rblk_start = tp->reportblk.rblk_end;
586 }
587 /* no enclosing block to report since ACK advanced */
c7e6499a 588 tp->sack_flags &= ~TSACK_F_ENCLOSESEG;
91489f6b 589 flags = q->tqe_th->th_flags & TH_FIN;
0f9e45de
SZ
590 TAILQ_REMOVE(&tp->t_segq, q, tqe_q);
591 KASSERT(TAILQ_EMPTY(&tp->t_segq) ||
592 TAILQ_FIRST(&tp->t_segq)->tqe_th->th_seq != tp->rcv_nxt,
91489f6b 593 ("segment not coalesced"));
6cef7136 594 if (so->so_state & SS_CANTRCVMORE) {
91489f6b 595 m_freem(q->tqe_m);
6cef7136
MD
596 } else {
597 lwkt_gettoken(&so->so_rcv.ssb_token);
6d49aa6f 598 ssb_appendstream(&so->so_rcv, q->tqe_m);
6cef7136
MD
599 lwkt_reltoken(&so->so_rcv.ssb_token);
600 }
efda3bd0 601 kfree(q, M_TSEGQ);
2d23a8be 602 atomic_add_int(&tcp_reass_qsize, -1);
984263bc
MD
603 ND6_HINT(tp);
604 sorwakeup(so);
605 return (flags);
606}
607
608/*
609 * TCP input routine, follows pages 65-76 of the
610 * protocol specification dated September, 1981 very closely.
611 */
612#ifdef INET6
613int
95b22adf 614tcp6_input(struct mbuf **mp, int *offp, int proto)
984263bc 615{
2256ba69 616 struct mbuf *m = *mp;
984263bc
MD
617 struct in6_ifaddr *ia6;
618
619 IP6_EXTHDR_CHECK(m, *offp, sizeof(struct tcphdr), IPPROTO_DONE);
620
621 /*
622 * draft-itojun-ipv6-tcp-to-anycast
623 * better place to put this in?
624 */
625 ia6 = ip6_getdstifaddr(m);
d24ce1dc 626 if (ia6 && (ia6->ia6_flags & IN6_IFF_ANYCAST)) {
984263bc
MD
627 struct ip6_hdr *ip6;
628
629 ip6 = mtod(m, struct ip6_hdr *);
630 icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR,
f23061d4 631 offsetof(struct ip6_hdr, ip6_dst));
d24ce1dc 632 return (IPPROTO_DONE);
984263bc
MD
633 }
634
002c1265 635 tcp_input(mp, offp, proto);
d24ce1dc 636 return (IPPROTO_DONE);
984263bc
MD
637}
638#endif
639
002c1265
MD
640int
641tcp_input(struct mbuf **mp, int *offp, int proto)
984263bc 642{
002c1265 643 int off0;
2256ba69
RG
644 struct tcphdr *th;
645 struct ip *ip = NULL;
646 struct ipovly *ipov;
647 struct inpcb *inp = NULL;
984263bc
MD
648 u_char *optp = NULL;
649 int optlen = 0;
b1992928
MD
650 int tlen, off;
651 int len = 0;
984263bc 652 int drop_hdrlen;
2256ba69
RG
653 struct tcpcb *tp = NULL;
654 int thflags;
4090d6ff 655 struct socket *so = NULL;
61896e3c 656 int todrop, acked;
27f4bf33
SZ
657 boolean_t ourfinisacked, needoutput = FALSE, delayed_dupack = FALSE;
658 tcp_seq th_dupack = 0; /* XXX gcc warning */
0a832381 659 u_int to_flags = 0; /* XXX gcc warning */
984263bc 660 u_long tiwin;
61896e3c 661 int recvwin;
984263bc 662 struct tcpopt to; /* options in this segment */
984263bc
MD
663 struct sockaddr_in *next_hop = NULL;
664 int rstreason; /* For badport_bandlim accounting purposes */
d371a63a 665 int cpu;
984263bc 666 struct ip6_hdr *ip6 = NULL;
002c1265 667 struct mbuf *m;
984263bc 668#ifdef INET6
d24ce1dc 669 boolean_t isipv6;
984263bc 670#else
d24ce1dc 671 const boolean_t isipv6 = FALSE;
984263bc
MD
672#endif
673#ifdef TCPDEBUG
674 short ostate = 0;
675#endif
676
002c1265
MD
677 off0 = *offp;
678 m = *mp;
679 *mp = NULL;
a00138cb 680
d24ce1dc
JH
681 tcpstat.tcps_rcvtotal++;
682
5de23090
SZ
683 if (m->m_pkthdr.fw_flags & IPFORWARD_MBUF_TAGGED) {
684 struct m_tag *mtag;
685
686 mtag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL);
687 KKASSERT(mtag != NULL);
688 next_hop = m_tag_data(mtag);
984263bc 689 }
d24ce1dc 690
984263bc 691#ifdef INET6
d24ce1dc 692 isipv6 = (mtod(m, struct ip *)->ip_v == 6) ? TRUE : FALSE;
984263bc 693#endif
984263bc
MD
694
695 if (isipv6) {
696 /* IP6_EXTHDR_CHECK() is already done at tcp6_input() */
697 ip6 = mtod(m, struct ip6_hdr *);
407e896e 698 tlen = (sizeof *ip6) + ntohs(ip6->ip6_plen) - off0;
984263bc
MD
699 if (in6_cksum(m, IPPROTO_TCP, off0, tlen)) {
700 tcpstat.tcps_rcvbadsum++;
701 goto drop;
702 }
703 th = (struct tcphdr *)((caddr_t)ip6 + off0);
704
705 /*
706 * Be proactive about unspecified IPv6 address in source.
707 * As we use all-zero to indicate unbounded/unconnected pcb,
708 * unspecified IPv6 address can be used to confuse us.
709 *
710 * Note that packets with unspecified IPv6 destination is
711 * already dropped in ip6_input.
712 */
713 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) {
714 /* XXX stat */
715 goto drop;
716 }
717 } else {
718 /*
719 * Get IP and TCP header together in first mbuf.
720 * Note: IP leaves IP header in first mbuf.
721 */
722 if (off0 > sizeof(struct ip)) {
bddf0751 723 ip_stripoptions(m);
984263bc
MD
724 off0 = sizeof(struct ip);
725 }
55d829f8
JH
726 /* already checked and pulled up in ip_demux() */
727 KASSERT(m->m_len >= sizeof(struct tcpiphdr),
61896e3c 728 ("TCP header not in one mbuf: m->m_len %d", m->m_len));
984263bc
MD
729 ip = mtod(m, struct ip *);
730 ipov = (struct ipovly *)ip;
731 th = (struct tcphdr *)((caddr_t)ip + off0);
732 tlen = ip->ip_len;
733
734 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) {
735 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR)
736 th->th_sum = m->m_pkthdr.csum_data;
737 else
738 th->th_sum = in_pseudo(ip->ip_src.s_addr,
739 ip->ip_dst.s_addr,
740 htonl(m->m_pkthdr.csum_data +
741 ip->ip_len +
742 IPPROTO_TCP));
743 th->th_sum ^= 0xffff;
744 } else {
745 /*
746 * Checksum extended TCP header and data.
747 */
748 len = sizeof(struct ip) + tlen;
407e896e 749 bzero(ipov->ih_x1, sizeof ipov->ih_x1);
984263bc
MD
750 ipov->ih_len = (u_short)tlen;
751 ipov->ih_len = htons(ipov->ih_len);
752 th->th_sum = in_cksum(m, len);
753 }
754 if (th->th_sum) {
755 tcpstat.tcps_rcvbadsum++;
756 goto drop;
757 }
758#ifdef INET6
759 /* Re-initialization for later version check */
760 ip->ip_v = IPVERSION;
761#endif
762 }
763
764 /*
765 * Check that TCP offset makes sense,
766 * pull out TCP options and adjust length. XXX
767 */
768 off = th->th_off << 2;
55d829f8
JH
769 /* already checked and pulled up in ip_demux() */
770 KASSERT(off >= sizeof(struct tcphdr) && off <= tlen,
61896e3c 771 ("bad TCP data offset %d (tlen %d)", off, tlen));
984263bc
MD
772 tlen -= off; /* tlen is used instead of ti->ti_len */
773 if (off > sizeof(struct tcphdr)) {
774 if (isipv6) {
002c1265 775 IP6_EXTHDR_CHECK(m, off0, off, IPPROTO_DONE);
984263bc
MD
776 ip6 = mtod(m, struct ip6_hdr *);
777 th = (struct tcphdr *)((caddr_t)ip6 + off0);
778 } else {
55d829f8
JH
779 /* already pulled up in ip_demux() */
780 KASSERT(m->m_len >= sizeof(struct ip) + off,
61896e3c
JH
781 ("TCP header and options not in one mbuf: "
782 "m_len %d, off %d", m->m_len, off));
984263bc
MD
783 }
784 optlen = off - sizeof(struct tcphdr);
785 optp = (u_char *)(th + 1);
786 }
787 thflags = th->th_flags;
788
789#ifdef TCP_DROP_SYNFIN
790 /*
791 * If the drop_synfin option is enabled, drop all packets with
792 * both the SYN and FIN bits set. This prevents e.g. nmap from
793 * identifying the TCP/IP stack.
794 *
795 * This is a violation of the TCP specification.
796 */
61896e3c 797 if (drop_synfin && (thflags & (TH_SYN | TH_FIN)) == (TH_SYN | TH_FIN))
984263bc
MD
798 goto drop;
799#endif
800
801 /*
802 * Convert TCP protocol specific fields to host format.
803 */
804 th->th_seq = ntohl(th->th_seq);
805 th->th_ack = ntohl(th->th_ack);
806 th->th_win = ntohs(th->th_win);
807 th->th_urp = ntohs(th->th_urp);
808
809 /*
d24ce1dc 810 * Delay dropping TCP, IP headers, IPv6 ext headers, and TCP options,
984263bc
MD
811 * until after ip6_savecontrol() is called and before other functions
812 * which don't want those proto headers.
813 * Because ip6_savecontrol() is going to parse the mbuf to
814 * search for data to be passed up to user-land, it wants mbuf
815 * parameters to be unchanged.
816 * XXX: the call of ip6_savecontrol() has been obsoleted based on
817 * latest version of the advanced API (20020110).
818 */
819 drop_hdrlen = off0 + off;
820
821 /*
822 * Locate pcb for segment.
823 */
824findpcb:
825 /* IPFIREWALL_FORWARD section */
d24ce1dc 826 if (next_hop != NULL && !isipv6) { /* IPv6 support is not there yet */
984263bc
MD
827 /*
828 * Transparently forwarded. Pretend to be the destination.
d24ce1dc 829 * already got one like this?
984263bc 830 */
6ca1a1cd 831 cpu = mycpu->gd_cpuid;
6ca1a1cd 832 inp = in_pcblookup_hash(&tcbinfo[cpu],
d371a63a 833 ip->ip_src, th->th_sport,
984263bc
MD
834 ip->ip_dst, th->th_dport,
835 0, m->m_pkthdr.rcvif);
836 if (!inp) {
83be63fe
JH
837 /*
838 * It's new. Try to find the ambushing socket.
839 */
840
841 /*
842 * The rest of the ipfw code stores the port in
843 * host order. XXX
844 * (The IP address is still in network order.)
845 */
846 in_port_t dport = next_hop->sin_port ?
847 htons(next_hop->sin_port) :
848 th->th_dport;
849
d371a63a 850 cpu = tcp_addrcpu(ip->ip_src.s_addr, th->th_sport,
83be63fe 851 next_hop->sin_addr.s_addr, dport);
d371a63a 852 inp = in_pcblookup_hash(&tcbinfo[cpu],
984263bc 853 ip->ip_src, th->th_sport,
83be63fe 854 next_hop->sin_addr, dport,
984263bc
MD
855 1, m->m_pkthdr.rcvif);
856 }
857 } else {
6ca1a1cd 858 if (isipv6) {
d371a63a 859 inp = in6_pcblookup_hash(&tcbinfo[0],
984263bc
MD
860 &ip6->ip6_src, th->th_sport,
861 &ip6->ip6_dst, th->th_dport,
862 1, m->m_pkthdr.rcvif);
6ca1a1cd 863 } else {
6ca1a1cd 864 cpu = mycpu->gd_cpuid;
6ca1a1cd 865 inp = in_pcblookup_hash(&tcbinfo[cpu],
984263bc
MD
866 ip->ip_src, th->th_sport,
867 ip->ip_dst, th->th_dport,
868 1, m->m_pkthdr.rcvif);
6ca1a1cd 869 }
984263bc 870 }
984263bc
MD
871
872 /*
873 * If the state is CLOSED (i.e., TCB does not exist) then
874 * all data in the incoming segment is discarded.
875 * If the TCB exists but is in CLOSED state, it is embryonic,
876 * but should either do a listen or a connect soon.
877 */
878 if (inp == NULL) {
879 if (log_in_vain) {
880#ifdef INET6
881 char dbuf[INET6_ADDRSTRLEN+2], sbuf[INET6_ADDRSTRLEN+2];
882#else
1141eb20
JH
883 char dbuf[sizeof "aaa.bbb.ccc.ddd"];
884 char sbuf[sizeof "aaa.bbb.ccc.ddd"];
984263bc
MD
885#endif
886 if (isipv6) {
887 strcpy(dbuf, "[");
984263bc 888 strcat(dbuf, ip6_sprintf(&ip6->ip6_dst));
984263bc 889 strcat(dbuf, "]");
95b22adf
JH
890 strcpy(sbuf, "[");
891 strcat(sbuf, ip6_sprintf(&ip6->ip6_src));
984263bc
MD
892 strcat(sbuf, "]");
893 } else {
894 strcpy(dbuf, inet_ntoa(ip->ip_dst));
895 strcpy(sbuf, inet_ntoa(ip->ip_src));
896 }
897 switch (log_in_vain) {
898 case 1:
61896e3c 899 if (!(thflags & TH_SYN))
984263bc
MD
900 break;
901 case 2:
902 log(LOG_INFO,
903 "Connection attempt to TCP %s:%d "
904 "from %s:%d flags:0x%02x\n",
905 dbuf, ntohs(th->th_dport), sbuf,
906 ntohs(th->th_sport), thflags);
907 break;
908 default:
909 break;
910 }
911 }
d24ce1dc 912 if (blackhole) {
984263bc
MD
913 switch (blackhole) {
914 case 1:
915 if (thflags & TH_SYN)
916 goto drop;
917 break;
918 case 2:
919 goto drop;
920 default:
921 goto drop;
922 }
923 }
924 rstreason = BANDLIM_RST_CLOSEDPORT;
925 goto dropwithreset;
926 }
61896e3c
JH
927
928#ifdef IPSEC
929 if (isipv6) {
930 if (ipsec6_in_reject_so(m, inp->inp_socket)) {
931 ipsec6stat.in_polvio++;
932 goto drop;
933 }
934 } else {
935 if (ipsec4_in_reject_so(m, inp->inp_socket)) {
936 ipsecstat.in_polvio++;
937 goto drop;
938 }
939 }
940#endif
941#ifdef FAST_IPSEC
942 if (isipv6) {
943 if (ipsec6_in_reject(m, inp))
944 goto drop;
945 } else {
946 if (ipsec4_in_reject(m, inp))
947 goto drop;
948 }
949#endif
95926362
MD
950 /* Check the minimum TTL for socket. */
951#ifdef INET6
952 if ((isipv6 ? ip6->ip6_hlim : ip->ip_ttl) < inp->inp_ip_minttl)
953 goto drop;
954#endif
61896e3c 955
984263bc
MD
956 tp = intotcpcb(inp);
957 if (tp == NULL) {
958 rstreason = BANDLIM_RST_CLOSEDPORT;
959 goto dropwithreset;
960 }
eb594563 961 if (tp->t_state <= TCPS_CLOSED)
984263bc
MD
962 goto drop;
963
984263bc 964 so = inp->inp_socket;
47654766 965
984263bc 966#ifdef TCPDEBUG
47654766
JH
967 if (so->so_options & SO_DEBUG) {
968 ostate = tp->t_state;
969 if (isipv6)
95b22adf 970 bcopy(ip6, tcp_saveipgen, sizeof(*ip6));
47654766 971 else
95b22adf 972 bcopy(ip, tcp_saveipgen, sizeof(*ip));
47654766
JH
973 tcp_savetcp = *th;
974 }
984263bc 975#endif
47654766 976
407e896e 977 bzero(&to, sizeof to);
d24ce1dc 978
47654766
JH
979 if (so->so_options & SO_ACCEPTCONN) {
980 struct in_conninfo inc;
981
984263bc 982#ifdef INET6
d24ce1dc 983 inc.inc_isipv6 = (isipv6 == TRUE);
984263bc
MD
984#endif
985 if (isipv6) {
986 inc.inc6_faddr = ip6->ip6_src;
987 inc.inc6_laddr = ip6->ip6_dst;
988 inc.inc6_route.ro_rt = NULL; /* XXX */
989 } else {
990 inc.inc_faddr = ip->ip_src;
991 inc.inc_laddr = ip->ip_dst;
992 inc.inc_route.ro_rt = NULL; /* XXX */
993 }
994 inc.inc_fport = th->th_sport;
995 inc.inc_lport = th->th_dport;
996
61896e3c
JH
997 /*
998 * If the state is LISTEN then ignore segment if it contains
984263bc
MD
999 * a RST. If the segment contains an ACK then it is bad and
1000 * send a RST. If it does not contain a SYN then it is not
1001 * interesting; drop it.
1002 *
1003 * If the state is SYN_RECEIVED (syncache) and seg contains
1004 * an ACK, but not for our SYN/ACK, send a RST. If the seg
1005 * contains a RST, check the sequence number to see if it
1006 * is a valid reset segment.
1007 */
61896e3c
JH
1008 if ((thflags & (TH_RST | TH_ACK | TH_SYN)) != TH_SYN) {
1009 if ((thflags & (TH_RST | TH_ACK | TH_SYN)) == TH_ACK) {
984263bc
MD
1010 if (!syncache_expand(&inc, th, &so, m)) {
1011 /*
1012 * No syncache entry, or ACK was not
1013 * for our SYN/ACK. Send a RST.
1014 */
1015 tcpstat.tcps_badsyn++;
1016 rstreason = BANDLIM_RST_OPENPORT;
1017 goto dropwithreset;
1018 }
2d23a8be
MD
1019
1020 /*
1021 * Could not complete 3-way handshake,
1022 * connection is being closed down, and
1023 * syncache will free mbuf.
1024 */
984263bc 1025 if (so == NULL)
002c1265 1026 return(IPPROTO_DONE);
2d23a8be
MD
1027
1028 /*
1029 * We must be in the correct protocol thread
1030 * for this connection.
1031 */
1032 KKASSERT(so->so_port == &curthread->td_msgport);
1033
984263bc
MD
1034 /*
1035 * Socket is created in state SYN_RECEIVED.
1036 * Continue processing segment.
1037 */
ed894f8c 1038 inp = so->so_pcb;
984263bc
MD
1039 tp = intotcpcb(inp);
1040 /*
1041 * This is what would have happened in
1042 * tcp_output() when the SYN,ACK was sent.
1043 */
1044 tp->snd_up = tp->snd_una;
1045 tp->snd_max = tp->snd_nxt = tp->iss + 1;
1046 tp->last_ack_sent = tp->rcv_nxt;
df1d2774 1047
984263bc
MD
1048 goto after_listen;
1049 }
1050 if (thflags & TH_RST) {
1051 syncache_chkrst(&inc, th);
1052 goto drop;
1053 }
1054 if (thflags & TH_ACK) {
1055 syncache_badack(&inc);
1056 tcpstat.tcps_badsyn++;
1057 rstreason = BANDLIM_RST_OPENPORT;
1058 goto dropwithreset;
1059 }
1060 goto drop;
1061 }
1062
1063 /*
61896e3c 1064 * Segment's flags are (SYN) or (SYN | FIN).
984263bc
MD
1065 */
1066#ifdef INET6
1067 /*
1068 * If deprecated address is forbidden,
1069 * we do not accept SYN to deprecated interface
1070 * address to prevent any new inbound connection from
1071 * getting established.
1072 * When we do not accept SYN, we send a TCP RST,
1073 * with deprecated source address (instead of dropping
1074 * it). We compromise it as it is much better for peer
1075 * to send a RST, and RST will be the final packet
1076 * for the exchange.
1077 *
1078 * If we do not forbid deprecated addresses, we accept
1079 * the SYN packet. RFC2462 does not suggest dropping
1080 * SYN in this case.
1081 * If we decipher RFC2462 5.5.4, it says like this:
1082 * 1. use of deprecated addr with existing
1083 * communication is okay - "SHOULD continue to be
1084 * used"
1085 * 2. use of it with new communication:
1086 * (2a) "SHOULD NOT be used if alternate address
61896e3c 1087 * with sufficient scope is available"
984263bc
MD
1088 * (2b) nothing mentioned otherwise.
1089 * Here we fall into (2b) case as we have no choice in
1090 * our source address selection - we must obey the peer.
1091 *
1092 * The wording in RFC2462 is confusing, and there are
1093 * multiple description text for deprecated address
1094 * handling - worse, they are not exactly the same.
1095 * I believe 5.5.4 is the best one, so we follow 5.5.4.
1096 */
1097 if (isipv6 && !ip6_use_deprecated) {
1098 struct in6_ifaddr *ia6;
1099
1100 if ((ia6 = ip6_getdstifaddr(m)) &&
1101 (ia6->ia6_flags & IN6_IFF_DEPRECATED)) {
1102 tp = NULL;
1103 rstreason = BANDLIM_RST_OPENPORT;
1104 goto dropwithreset;
1105 }
1106 }
1107#endif
1108 /*
1109 * If it is from this socket, drop it, it must be forged.
1110 * Don't bother responding if the destination was a broadcast.
1111 */
1112 if (th->th_dport == th->th_sport) {
1113 if (isipv6) {
1114 if (IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst,
1115 &ip6->ip6_src))
1116 goto drop;
1117 } else {
1118 if (ip->ip_dst.s_addr == ip->ip_src.s_addr)
1119 goto drop;
1120 }
1121 }
1122 /*
1123 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN
1124 *
1125 * Note that it is quite possible to receive unicast
1126 * link-layer packets with a broadcast IP address. Use
1127 * in_broadcast() to find them.
1128 */
61896e3c 1129 if (m->m_flags & (M_BCAST | M_MCAST))
984263bc
MD
1130 goto drop;
1131 if (isipv6) {
1132 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
1133 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src))
1134 goto drop;
1135 } else {
1136 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) ||
1137 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
1138 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) ||
1139 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif))
1140 goto drop;
1141 }
1142 /*
1143 * SYN appears to be valid; create compressed TCP state
1144 * for syncache, or perform t/tcp connection.
1145 */
1146 if (so->so_qlen <= so->so_qlimit) {
6c1bbf57 1147 tcp_dooptions(&to, optp, optlen, TRUE, th->th_ack);
b09567cc 1148 if (!syncache_add(&inc, &to, th, so, m))
984263bc 1149 goto drop;
2d23a8be
MD
1150
1151 /*
1152 * Entry added to syncache, mbuf used to
1153 * send SYN,ACK packet.
1154 */
b09567cc 1155 return(IPPROTO_DONE);
984263bc
MD
1156 }
1157 goto drop;
1158 }
984263bc 1159
2d23a8be
MD
1160after_listen:
1161 /*
1162 * Should not happen - syncache should pick up these connections.
1163 *
1164 * Once we are past handling listen sockets we must be in the
1165 * correct protocol processing thread.
1166 */
61896e3c 1167 KASSERT(tp->t_state != TCPS_LISTEN, ("tcp_input: TCPS_LISTEN state"));
2d23a8be 1168 KKASSERT(so->so_port == &curthread->td_msgport);
984263bc 1169
df1d2774
SZ
1170 /* Unscale the window into a 32-bit value. */
1171 if (!(thflags & TH_SYN))
1172 tiwin = th->th_win << tp->snd_scale;
1173 else
1174 tiwin = th->th_win;
1175
984263bc 1176 /*
5b0b9fa5
PA
1177 * This is the second part of the MSS DoS prevention code (after
1178 * minmss on the sending side) and it deals with too many too small
1179 * tcp packets in a too short timeframe (1 second).
1180 *
153d34ac
MD
1181 * XXX Removed. This code was crap. It does not scale to network
1182 * speed, and default values break NFS. Gone.
5b0b9fa5 1183 */
153d34ac 1184 /* REMOVED */
5b0b9fa5
PA
1185
1186 /*
984263bc 1187 * Segment received on connection.
efca2b8e
MD
1188 *
1189 * Reset idle time and keep-alive timer. Don't waste time if less
0ecd93f9 1190 * then a second has elapsed.
984263bc 1191 */
0ecd93f9
MD
1192 if ((int)(ticks - tp->t_rcvtime) > hz)
1193 tcp_timer_keep_activity(tp, thflags);
984263bc
MD
1194
1195 /*
1196 * Process options.
1197 * XXX this is tradtitional behavior, may need to be cleaned up.
1198 */
6c1bbf57 1199 tcp_dooptions(&to, optp, optlen, (thflags & TH_SYN) != 0, th->th_ack);
ad0af98b 1200 if (tp->t_state == TCPS_SYN_SENT && (thflags & TH_SYN)) {
df1d2774 1201 if ((to.to_flags & TOF_SCALE) && (tp->t_flags & TF_REQ_SCALE)) {
984263bc 1202 tp->t_flags |= TF_RCVD_SCALE;
df1d2774 1203 tp->snd_scale = to.to_requested_s_scale;
984263bc 1204 }
df1d2774
SZ
1205
1206 /*
1207 * Initial send window; will be updated upon next ACK
1208 */
1209 tp->snd_wnd = th->th_win;
1210
984263bc
MD
1211 if (to.to_flags & TOF_TS) {
1212 tp->t_flags |= TF_RCVD_TSTMP;
1213 tp->ts_recent = to.to_tsval;
1214 tp->ts_recent_age = ticks;
1215 }
f34fd0f2
SZ
1216 if (!(to.to_flags & TOF_MSS))
1217 to.to_mss = 0;
1218 tcp_mss(tp, to.to_mss);
91489f6b
JH
1219 /*
1220 * Only set the TF_SACK_PERMITTED per-connection flag
1221 * if we got a SACK_PERMITTED option from the other side
1222 * and the global tcp_do_sack variable is true.
1223 */
1224 if (tcp_do_sack && (to.to_flags & TOF_SACK_PERMITTED))
1225 tp->t_flags |= TF_SACK_PERMITTED;
984263bc
MD
1226 }
1227
1228 /*
1229 * Header prediction: check for the two common cases
1230 * of a uni-directional data xfer. If the packet has
1231 * no control flags, is in-sequence, the window didn't
1232 * change and we're not retransmitting, it's a
1233 * candidate. If the length is zero and the ack moved
1234 * forward, we're the sender side of the xfer. Just
1235 * free the data acked & wake any higher level process
1236 * that was blocked waiting for space. If the length
1237 * is non-zero and the ack didn't move, we're the
1238 * receiver side. If we're getting packets in-order
1239 * (the reassembly queue is empty), add the data to
1240 * the socket buffer and note that we need a delayed ack.
1241 * Make sure that the hidden state-flags are also off.
1242 * Since we check for TCPS_ESTABLISHED above, it can only
1243 * be TH_NEEDSYN.
1244 */
1245 if (tp->t_state == TCPS_ESTABLISHED &&
1246 (thflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK &&
61896e3c
JH
1247 !(tp->t_flags & (TF_NEEDSYN | TF_NEEDFIN)) &&
1248 (!(to.to_flags & TOF_TS) ||
984263bc 1249 TSTMP_GEQ(to.to_tsval, tp->ts_recent)) &&
984263bc 1250 th->th_seq == tp->rcv_nxt &&
984263bc
MD
1251 tp->snd_nxt == tp->snd_max) {
1252
1253 /*
1254 * If last ACK falls within this segment's sequence numbers,
1255 * record the timestamp.
1256 * NOTE that the test is modified according to the latest
1257 * proposal of the tcplw@cray.com list (Braden 1993/04/26).
1258 */
61896e3c 1259 if ((to.to_flags & TOF_TS) &&
984263bc
MD
1260 SEQ_LEQ(th->th_seq, tp->last_ack_sent)) {
1261 tp->ts_recent_age = ticks;
1262 tp->ts_recent = to.to_tsval;
1263 }
1264
1265 if (tlen == 0) {
1266 if (SEQ_GT(th->th_ack, tp->snd_una) &&
1267 SEQ_LEQ(th->th_ack, tp->snd_max) &&
1268 tp->snd_cwnd >= tp->snd_wnd &&
95b22adf 1269 !IN_FASTRECOVERY(tp)) {
984263bc 1270 /*
be23faf1 1271 * This is a pure ack for outstanding data.
984263bc
MD
1272 */
1273 ++tcpstat.tcps_predack;
1274 /*
1275 * "bad retransmit" recovery
bfdb979e
JH
1276 *
1277 * If Eifel detection applies, then
1278 * it is deterministic, so use it
1279 * unconditionally over the old heuristic.
1280 * Otherwise, fall back to the old heuristic.
984263bc 1281 */
bfdb979e
JH
1282 if (tcp_do_eifel_detect &&
1283 (to.to_flags & TOF_TS) && to.to_tsecr &&
1c8b7a61 1284 (tp->rxt_flags & TRXT_F_FIRSTACCACK)) {
bfdb979e
JH
1285 /* Eifel detection applicable. */
1286 if (to.to_tsecr < tp->t_rexmtTS) {
1287 tcp_revert_congestion_state(tp);
1288 ++tcpstat.tcps_eifeldetected;
928c3291
SZ
1289 if (tp->t_rxtshift != 1 ||
1290 ticks >= tp->t_badrxtwin)
1291 ++tcpstat.tcps_rttcantdetect;
bfdb979e
JH
1292 }
1293 } else if (tp->t_rxtshift == 1 &&
1294 ticks < tp->t_badrxtwin) {
1295 tcp_revert_congestion_state(tp);
1296 ++tcpstat.tcps_rttdetected;
984263bc 1297 }
1c8b7a61
SZ
1298 tp->rxt_flags &= ~(TRXT_F_FIRSTACCACK |
1299 TRXT_F_FASTREXMT | TRXT_F_EARLYREXMT);
984263bc
MD
1300 /*
1301 * Recalculate the retransmit timer / rtt.
1302 *
d24ce1dc 1303 * Some machines (certain windows boxes)
984263bc
MD
1304 * send broken timestamp replies during the
1305 * SYN+ACK phase, ignore timestamps of 0.
1306 */
95b22adf 1307 if ((to.to_flags & TOF_TS) && to.to_tsecr) {
984263bc 1308 tcp_xmit_timer(tp,
073ec6c4
SZ
1309 ticks - to.to_tsecr + 1,
1310 th->th_ack);
984263bc 1311 } else if (tp->t_rtttime &&
95b22adf 1312 SEQ_GT(th->th_ack, tp->t_rtseq)) {
984263bc 1313 tcp_xmit_timer(tp,
073ec6c4
SZ
1314 ticks - tp->t_rtttime,
1315 th->th_ack);
984263bc
MD
1316 }
1317 tcp_xmit_bandwidth_limit(tp, th->th_ack);
1318 acked = th->th_ack - tp->snd_una;
1319 tcpstat.tcps_rcvackpack++;
1320 tcpstat.tcps_rcvackbyte += acked;
6d49aa6f 1321 sbdrop(&so->so_snd.sb, acked);
cfb3f3f4 1322 tp->snd_recover = th->th_ack - 1;
9845754e 1323 tp->snd_una = th->th_ack;
984263bc 1324 tp->t_dupacks = 0;
df9d7670
JH
1325 /*
1326 * Update window information.
1327 */
1328 if (tiwin != tp->snd_wnd &&
1329 acceptable_window_update(tp, th, tiwin)) {
1330 /* keep track of pure window updates */
1331 if (tp->snd_wl2 == th->th_ack &&
1332 tiwin > tp->snd_wnd)
1333 tcpstat.tcps_rcvwinupd++;
1334 tp->snd_wnd = tiwin;
1335 tp->snd_wl1 = th->th_seq;
1336 tp->snd_wl2 = th->th_ack;
1337 if (tp->snd_wnd > tp->max_sndwnd)
1338 tp->max_sndwnd = tp->snd_wnd;
1339 }
984263bc
MD
1340 m_freem(m);
1341 ND6_HINT(tp); /* some progress has been done */
984263bc
MD
1342 /*
1343 * If all outstanding data are acked, stop
1344 * retransmit timer, otherwise restart timer
1345 * using current (possibly backed-off) value.
1346 * If process is waiting for space,
1347 * wakeup/selwakeup/signal. If data
1348 * are ready to send, let tcp_output
1349 * decide between more output or persist.
1350 */
a48c5dd5
SZ
1351 if (tp->snd_una == tp->snd_max) {
1352 tcp_callout_stop(tp, tp->tt_rexmt);
1353 } else if (!tcp_callout_active(tp,
1354 tp->tt_persist)) {
1355 tcp_callout_reset(tp, tp->tt_rexmt,
1356 tp->t_rxtcur, tcp_timer_rexmt);
1357 }
984263bc 1358 sowwakeup(so);
6d49aa6f 1359 if (so->so_snd.ssb_cc > 0)
f23061d4 1360 tcp_output(tp);
002c1265 1361 return(IPPROTO_DONE);
984263bc 1362 }
df9d7670
JH
1363 } else if (tiwin == tp->snd_wnd &&
1364 th->th_ack == tp->snd_una &&
0f9e45de 1365 TAILQ_EMPTY(&tp->t_segq) &&
6d49aa6f 1366 tlen <= ssb_space(&so->so_rcv)) {
46e92930 1367 u_long newsize = 0; /* automatic sockbuf scaling */
984263bc 1368 /*
be23faf1 1369 * This is a pure, in-sequence data packet
984263bc
MD
1370 * with nothing on the reassembly queue and
1371 * we have enough buffer space to take it.
1372 */
1373 ++tcpstat.tcps_preddat;
1374 tp->rcv_nxt += tlen;
1375 tcpstat.tcps_rcvpack++;
1376 tcpstat.tcps_rcvbyte += tlen;
1377 ND6_HINT(tp); /* some progress has been done */
5b0b9fa5
PA
1378 /*
1379 * Automatic sizing of receive socket buffer. Often the send
1380 * buffer size is not optimally adjusted to the actual network
1381 * conditions at hand (delay bandwidth product). Setting the
1382 * buffer size too small limits throughput on links with high
1383 * bandwidth and high delay (eg. trans-continental/oceanic links).
1384 *
1385 * On the receive side the socket buffer memory is only rarely
1386 * used to any significant extent. This allows us to be much
1387 * more aggressive in scaling the receive socket buffer. For
1388 * the case that the buffer space is actually used to a large
1389 * extent and we run out of kernel memory we can simply drop
1390 * the new segments; TCP on the sender will just retransmit it
1391 * later. Setting the buffer size too big may only consume too
1392 * much kernel memory if the application doesn't read() from
1393 * the socket or packet loss or reordering makes use of the
1394 * reassembly queue.
1395 *
1396 * The criteria to step up the receive buffer one notch are:
1397 * 1. the number of bytes received during the time it takes
1398 * one timestamp to be reflected back to us (the RTT);
1399 * 2. received bytes per RTT is within seven eighth of the
1400 * current socket buffer size;
1401 * 3. receive buffer size has not hit maximal automatic size;
1402 *
1403 * This algorithm does one step per RTT at most and only if
1404 * we receive a bulk stream w/o packet losses or reorderings.
1405 * Shrinking the buffer during idle times is not necessary as
1406 * it doesn't consume any memory when idle.
1407 *
1408 * TODO: Only step up if the application is actually serving
1409 * the buffer to better manage the socket buffer resources.
1410 */
1411 if (tcp_do_autorcvbuf &&
1412 to.to_tsecr &&
1413 (so->so_rcv.ssb_flags & SSB_AUTOSIZE)) {
1414 if (to.to_tsecr > tp->rfbuf_ts &&
1415 to.to_tsecr - tp->rfbuf_ts < hz) {
1416 if (tp->rfbuf_cnt >
1417 (so->so_rcv.ssb_hiwat / 8 * 7) &&
1418 so->so_rcv.ssb_hiwat <
1419 tcp_autorcvbuf_max) {
1420 newsize =
46e92930
MD
1421 ulmin(so->so_rcv.ssb_hiwat +
1422 tcp_autorcvbuf_inc,
1423 tcp_autorcvbuf_max);
5b0b9fa5
PA
1424 }
1425 /* Start over with next RTT. */
1426 tp->rfbuf_ts = 0;
1427 tp->rfbuf_cnt = 0;
1428 } else
1429 tp->rfbuf_cnt += tlen; /* add up */
1430 }
984263bc
MD
1431 /*
1432 * Add data to socket buffer.
1433 */
1434 if (so->so_state & SS_CANTRCVMORE) {
1435 m_freem(m);
1436 } else {
5b0b9fa5 1437 /*
46e92930
MD
1438 * Set new socket buffer size, give up when
1439 * limit is reached.
1440 *
1441 * Adjusting the size can mess up ACK
1442 * sequencing when pure window updates are
1443 * being avoided (which is the default),
1444 * so force an ack.
5b0b9fa5 1445 */
6cef7136 1446 lwkt_gettoken(&so->so_rcv.ssb_token);
46e92930
MD
1447 if (newsize) {
1448 tp->t_flags |= TF_RXRESIZED;
5b0b9fa5 1449 if (!ssb_reserve(&so->so_rcv, newsize,
46e92930 1450 so, NULL)) {
14343ad3 1451 atomic_clear_int(&so->so_rcv.ssb_flags, SSB_AUTOSIZE);
46e92930
MD
1452 }
1453 if (newsize >=
1454 (TCP_MAXWIN << tp->rcv_scale)) {
14343ad3 1455 atomic_clear_int(&so->so_rcv.ssb_flags, SSB_AUTOSIZE);
46e92930
MD
1456 }
1457 }
09cf73e0 1458 m_adj(m, drop_hdrlen); /* delayed header drop */
6d49aa6f 1459 ssb_appendstream(&so->so_rcv, m);
6cef7136 1460 lwkt_reltoken(&so->so_rcv.ssb_token);
984263bc
MD
1461 }
1462 sorwakeup(so);
2b1ce38a
MD
1463 /*
1464 * This code is responsible for most of the ACKs
1465 * the TCP stack sends back after receiving a data
1466 * packet. Note that the DELAY_ACK check fails if
1467 * the delack timer is already running, which results
1468 * in an ack being sent every other packet (which is
1469 * what we want).
72b37eeb
MD
1470 *
1471 * We then further aggregate acks by not actually
1472 * sending one until the protocol thread has completed
1473 * processing the current backlog of packets. This
1474 * does not delay the ack any further, but allows us
1475 * to take advantage of the packet aggregation that
1476 * high speed NICs do (usually blocks of 8-10 packets)
1477 * to send a single ack rather then four or five acks,
1478 * greatly reducing the ack rate, the return channel
1479 * bandwidth, and the protocol overhead on both ends.
1480 *
1481 * Since this also has the effect of slowing down
1482 * the exponential slow-start ramp-up, systems with
1483 * very large bandwidth-delay products might want
1484 * to turn the feature off.
2b1ce38a 1485 */
984263bc 1486 if (DELAY_ACK(tp)) {
a48c5dd5
SZ
1487 tcp_callout_reset(tp, tp->tt_delack,
1488 tcp_delacktime, tcp_timer_delack);
72b37eeb 1489 } else if (tcp_aggregate_acks) {
984263bc 1490 tp->t_flags |= TF_ACKNOW;
61896e3c 1491 if (!(tp->t_flags & TF_ONOUTPUTQ)) {
2b1ce38a
MD
1492 tp->t_flags |= TF_ONOUTPUTQ;
1493 tp->tt_cpu = mycpu->gd_cpuid;
1494 TAILQ_INSERT_TAIL(
1495 &tcpcbackq[tp->tt_cpu],
1496 tp, t_outputq);
1497 }
72b37eeb
MD
1498 } else {
1499 tp->t_flags |= TF_ACKNOW;
1500 tcp_output(tp);
984263bc 1501 }
002c1265 1502 return(IPPROTO_DONE);
984263bc
MD
1503 }
1504 }
1505
1506 /*
1507 * Calculate amount of space in receive window,
1508 * and then do TCP input processing.
1509 * Receive window is amount of space in rcv queue,
1510 * but not less than advertised window.
1511 */
6d49aa6f 1512 recvwin = ssb_space(&so->so_rcv);
61896e3c
JH
1513 if (recvwin < 0)
1514 recvwin = 0;
1515 tp->rcv_wnd = imax(recvwin, (int)(tp->rcv_adv - tp->rcv_nxt));
984263bc 1516
5b0b9fa5
PA
1517 /* Reset receive buffer auto scaling when not in bulk receive mode. */
1518 tp->rfbuf_ts = 0;
1519 tp->rfbuf_cnt = 0;
1520
984263bc 1521 switch (tp->t_state) {
984263bc
MD
1522 /*
1523 * If the state is SYN_RECEIVED:
1524 * if seg contains an ACK, but not for our SYN/ACK, send a RST.
1525 */
1526 case TCPS_SYN_RECEIVED:
1527 if ((thflags & TH_ACK) &&
1528 (SEQ_LEQ(th->th_ack, tp->snd_una) ||
1529 SEQ_GT(th->th_ack, tp->snd_max))) {
1530 rstreason = BANDLIM_RST_OPENPORT;
1531 goto dropwithreset;
1532 }
1533 break;
1534
1535 /*
1536 * If the state is SYN_SENT:
1537 * if seg contains an ACK, but not for our SYN, drop the input.
1538 * if seg contains a RST, then drop the connection.
1539 * if seg does not contain SYN, then drop it.
1540 * Otherwise this is an acceptable SYN segment
1541 * initialize tp->rcv_nxt and tp->irs
1542 * if seg contains ack then advance tp->snd_una
1543 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state
1544 * arrange for segment to be acked (eventually)
1545 * continue processing rest of data/controls, beginning with URG
1546 */
1547 case TCPS_SYN_SENT:
984263bc
MD
1548 if ((thflags & TH_ACK) &&
1549 (SEQ_LEQ(th->th_ack, tp->iss) ||
1550 SEQ_GT(th->th_ack, tp->snd_max))) {
27b8aee3
AE
1551 rstreason = BANDLIM_UNLIMITED;
1552 goto dropwithreset;
984263bc
MD
1553 }
1554 if (thflags & TH_RST) {
1555 if (thflags & TH_ACK)
1556 tp = tcp_drop(tp, ECONNREFUSED);
1557 goto drop;
1558 }
61896e3c 1559 if (!(thflags & TH_SYN))
984263bc 1560 goto drop;
984263bc
MD
1561
1562 tp->irs = th->th_seq;
1563 tcp_rcvseqinit(tp);
1564 if (thflags & TH_ACK) {
27b8aee3 1565 /* Our SYN was acked. */
984263bc
MD
1566 tcpstat.tcps_connects++;
1567 soisconnected(so);
1568 /* Do window scaling on this connection? */
61896e3c 1569 if ((tp->t_flags & (TF_RCVD_SCALE | TF_REQ_SCALE)) ==
df1d2774 1570 (TF_RCVD_SCALE | TF_REQ_SCALE))
984263bc 1571 tp->rcv_scale = tp->request_r_scale;
984263bc
MD
1572 tp->rcv_adv += tp->rcv_wnd;
1573 tp->snd_una++; /* SYN is acked */
a48c5dd5 1574 tcp_callout_stop(tp, tp->tt_rexmt);
984263bc
MD
1575 /*
1576 * If there's data, delay ACK; if there's also a FIN
1577 * ACKNOW will be turned on later.
1578 */
a48c5dd5
SZ
1579 if (DELAY_ACK(tp) && tlen != 0) {
1580 tcp_callout_reset(tp, tp->tt_delack,
1581 tcp_delacktime, tcp_timer_delack);
1582 } else {
984263bc 1583 tp->t_flags |= TF_ACKNOW;
a48c5dd5 1584 }
984263bc
MD
1585 /*
1586 * Received <SYN,ACK> in SYN_SENT[*] state.
1587 * Transitions:
1588 * SYN_SENT --> ESTABLISHED
1589 * SYN_SENT* --> FIN_WAIT_1
1590 */
1591 tp->t_starttime = ticks;
1592 if (tp->t_flags & TF_NEEDFIN) {
1593 tp->t_state = TCPS_FIN_WAIT_1;
1594 tp->t_flags &= ~TF_NEEDFIN;
1595 thflags &= ~TH_SYN;
1596 } else {
8651f7f8 1597 tcp_established(tp);
984263bc
MD
1598 }
1599 } else {
1600 /*
95b22adf 1601 * Received initial SYN in SYN-SENT[*] state =>
27b8aee3
AE
1602 * simultaneous open.
1603 * Do 3-way handshake:
61896e3c
JH
1604 * SYN-SENT -> SYN-RECEIVED
1605 * SYN-SENT* -> SYN-RECEIVED*
95b22adf 1606 */
984263bc 1607 tp->t_flags |= TF_ACKNOW;
a48c5dd5 1608 tcp_callout_stop(tp, tp->tt_rexmt);
27b8aee3 1609 tp->t_state = TCPS_SYN_RECEIVED;
984263bc
MD
1610 }
1611
984263bc
MD
1612 /*
1613 * Advance th->th_seq to correspond to first data byte.
1614 * If data, trim to stay within window,
1615 * dropping FIN if necessary.
1616 */
1617 th->th_seq++;
1618 if (tlen > tp->rcv_wnd) {
1619 todrop = tlen - tp->rcv_wnd;
1620 m_adj(m, -todrop);
1621 tlen = tp->rcv_wnd;
1622 thflags &= ~TH_FIN;
1623 tcpstat.tcps_rcvpackafterwin++;
1624 tcpstat.tcps_rcvbyteafterwin += todrop;
1625 }
1626 tp->snd_wl1 = th->th_seq - 1;
1627 tp->rcv_up = th->th_seq;
1628 /*
1629 * Client side of transaction: already sent SYN and data.
1630 * If the remote host used T/TCP to validate the SYN,
1631 * our data will be ACK'd; if so, enter normal data segment
1632 * processing in the middle of step 5, ack processing.
1633 * Otherwise, goto step 6.
1634 */
95b22adf 1635 if (thflags & TH_ACK)
984263bc
MD
1636 goto process_ACK;
1637
1638 goto step6;
1639
1640 /*
1641 * If the state is LAST_ACK or CLOSING or TIME_WAIT:
27b8aee3 1642 * do normal processing (we no longer bother with T/TCP).
984263bc
MD
1643 */
1644 case TCPS_LAST_ACK:
1645 case TCPS_CLOSING:
1646 case TCPS_TIME_WAIT:
95b22adf 1647 break; /* continue normal processing */
984263bc
MD
1648 }
1649
1650 /*
1651 * States other than LISTEN or SYN_SENT.
1652 * First check the RST flag and sequence number since reset segments
1653 * are exempt from the timestamp and connection count tests. This
1654 * fixes a bug introduced by the Stevens, vol. 2, p. 960 bugfix
1655 * below which allowed reset segments in half the sequence space
1656 * to fall though and be processed (which gives forged reset
1657 * segments with a random sequence number a 50 percent chance of
1658 * killing a connection).
1659 * Then check timestamp, if present.
1660 * Then check the connection count, if present.
1661 * Then check that at least some bytes of segment are within
1662 * receive window. If segment begins before rcv_nxt,
1663 * drop leading data (and SYN); if nothing left, just ack.
1664 *
1665 *
1666 * If the RST bit is set, check the sequence number to see
1667 * if this is a valid reset segment.
1668 * RFC 793 page 37:
1669 * In all states except SYN-SENT, all reset (RST) segments
1670 * are validated by checking their SEQ-fields. A reset is
1671 * valid if its sequence number is in the window.
1672 * Note: this does not take into account delayed ACKs, so
1673 * we should test against last_ack_sent instead of rcv_nxt.
1674 * The sequence number in the reset segment is normally an
91489f6b 1675 * echo of our outgoing acknowledgement numbers, but some hosts
984263bc
MD
1676 * send a reset with the sequence number at the rightmost edge
1677 * of our receive window, and we have to handle this case.
1678 * If we have multiple segments in flight, the intial reset
1679 * segment sequence numbers will be to the left of last_ack_sent,
1680 * but they will eventually catch up.
1681 * In any case, it never made sense to trim reset segments to
1682 * fit the receive window since RFC 1122 says:
1683 * 4.2.2.12 RST Segment: RFC-793 Section 3.4
1684 *
1685 * A TCP SHOULD allow a received RST segment to include data.
1686 *
1687 * DISCUSSION
61896e3c
JH
1688 * It has been suggested that a RST segment could contain
1689 * ASCII text that encoded and explained the cause of the
91489f6b 1690 * RST. No standard has yet been established for such
61896e3c 1691 * data.
984263bc
MD
1692 *
1693 * If the reset segment passes the sequence number test examine
1694 * the state:
1695 * SYN_RECEIVED STATE:
1696 * If passive open, return to LISTEN state.
1697 * If active open, inform user that connection was refused.
1698 * ESTABLISHED, FIN_WAIT_1, FIN_WAIT_2, CLOSE_WAIT STATES:
1699 * Inform user that connection was reset, and close tcb.
1700 * CLOSING, LAST_ACK STATES:
1701 * Close the tcb.
1702 * TIME_WAIT STATE:
1703 * Drop the segment - see Stevens, vol. 2, p. 964 and
61896e3c 1704 * RFC 1337.
984263bc
MD
1705 */
1706 if (thflags & TH_RST) {
1707 if (SEQ_GEQ(th->th_seq, tp->last_ack_sent) &&
d4dbb5be 1708 SEQ_LEQ(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) {
984263bc
MD
1709 switch (tp->t_state) {
1710
1711 case TCPS_SYN_RECEIVED:
1712 so->so_error = ECONNREFUSED;
1713 goto close;
1714
1715 case TCPS_ESTABLISHED:
1716 case TCPS_FIN_WAIT_1:
1717 case TCPS_FIN_WAIT_2:
1718 case TCPS_CLOSE_WAIT:
1719 so->so_error = ECONNRESET;
1720 close:
1721 tp->t_state = TCPS_CLOSED;
1722 tcpstat.tcps_drops++;
1723 tp = tcp_close(tp);
1724 break;
1725
1726 case TCPS_CLOSING:
1727 case TCPS_LAST_ACK:
1728 tp = tcp_close(tp);
1729 break;
1730
1731 case TCPS_TIME_WAIT:
1732 break;
1733 }
1734 }
1735 goto drop;
1736 }
1737
1738 /*
1739 * RFC 1323 PAWS: If we have a timestamp reply on this segment
1740 * and it's less than ts_recent, drop it.
1741 */
61896e3c 1742 if ((to.to_flags & TOF_TS) && tp->ts_recent != 0 &&
984263bc 1743 TSTMP_LT(to.to_tsval, tp->ts_recent)) {
984263bc
MD
1744 /* Check to see if ts_recent is over 24 days old. */
1745 if ((int)(ticks - tp->ts_recent_age) > TCP_PAWS_IDLE) {
1746 /*
1747 * Invalidate ts_recent. If this segment updates
1748 * ts_recent, the age will be reset later and ts_recent
1749 * will get a valid value. If it does not, setting
1750 * ts_recent to zero will at least satisfy the
1751 * requirement that zero be placed in the timestamp
1752 * echo reply when ts_recent isn't valid. The
1753 * age isn't reset until we get a valid ts_recent
1754 * because we don't want out-of-order segments to be
1755 * dropped when ts_recent is old.
1756 */
1757 tp->ts_recent = 0;
9de1f696
SZ
1758 } else if (tcp_paws_tolerance && tlen != 0 &&
1759 tp->t_state == TCPS_ESTABLISHED &&
1760 (thflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK&&
1761 !(tp->t_flags & (TF_NEEDSYN | TF_NEEDFIN)) &&
1762 th->th_ack == tp->snd_una &&
1763 tiwin == tp->snd_wnd &&
1764 TSTMP_GEQ(to.to_tsval + tcp_paws_tolerance, tp->ts_recent)&&
1765 (th->th_seq == tp->rcv_nxt ||
1766 (SEQ_GT(th->th_seq, tp->rcv_nxt) &&
1767 tcp_paws_canreasslast(tp, th, tlen)))) {
1768 /*
1769 * This tends to prevent valid new segments from being
1770 * dropped by the reordered segments sent by the fast
1771 * retransmission algorithm on the sending side, i.e.
1772 * the fast retransmitted segment w/ larger timestamp
1773 * arrives earlier than the previously sent new segments
1774 * w/ smaller timestamp.
1775 *
1776 * If following conditions are met, the segment is
1777 * accepted:
1778 * - The segment contains data
1779 * - The connection is established
1780 * - The header does not contain important flags
1781 * - SYN or FIN is not needed
1782 * - It does not acknowledge new data
1783 * - Receive window is not changed
1784 * - The timestamp is within "acceptable" range
1785 * - The new segment is what we are expecting or
1786 * the new segment could be merged w/ the last
1787 * pending segment on the reassemble queue
1788 */
1789 tcpstat.tcps_pawsaccept++;
1790 tcpstat.tcps_pawsdrop++;
984263bc
MD
1791 } else {
1792 tcpstat.tcps_rcvduppack++;
1793 tcpstat.tcps_rcvdupbyte += tlen;
1794 tcpstat.tcps_pawsdrop++;
1795 if (tlen)
1796 goto dropafterack;
1797 goto drop;
1798 }
1799 }
1800
1801 /*
984263bc
MD
1802 * In the SYN-RECEIVED state, validate that the packet belongs to
1803 * this connection before trimming the data to fit the receive
1804 * window. Check the sequence number versus IRS since we know
1805 * the sequence numbers haven't wrapped. This is a partial fix
1806 * for the "LAND" DoS attack.
1807 */
1808 if (tp->t_state == TCPS_SYN_RECEIVED && SEQ_LT(th->th_seq, tp->irs)) {
1809 rstreason = BANDLIM_RST_OPENPORT;
1810 goto dropwithreset;
1811 }
1812
1813 todrop = tp->rcv_nxt - th->th_seq;
1814 if (todrop > 0) {
91489f6b
JH
1815 if (TCP_DO_SACK(tp)) {
1816 /* Report duplicate segment at head of packet. */
1817 tp->reportblk.rblk_start = th->th_seq;
3a5d999b
SZ
1818 tp->reportblk.rblk_end = TCP_SACK_BLKEND(
1819 th->th_seq + tlen, thflags);
91489f6b
JH
1820 if (SEQ_GT(tp->reportblk.rblk_end, tp->rcv_nxt))
1821 tp->reportblk.rblk_end = tp->rcv_nxt;
c7e6499a
SZ
1822 tp->sack_flags |= (TSACK_F_DUPSEG | TSACK_F_SACKLEFT);
1823 tp->t_flags |= TF_ACKNOW;
91489f6b 1824 }
984263bc
MD
1825 if (thflags & TH_SYN) {
1826 thflags &= ~TH_SYN;
1827 th->th_seq++;
1828 if (th->th_urp > 1)
1829 th->th_urp--;
1830 else
1831 thflags &= ~TH_URG;
1832 todrop--;
1833 }
1834 /*
1835 * Following if statement from Stevens, vol. 2, p. 960.
1836 */
61896e3c
JH
1837 if (todrop > tlen ||
1838 (todrop == tlen && !(thflags & TH_FIN))) {
984263bc
MD
1839 /*
1840 * Any valid FIN must be to the left of the window.
1841 * At this point the FIN must be a duplicate or out
1842 * of sequence; drop it.
1843 */
1844 thflags &= ~TH_FIN;
1845
1846 /*
1847 * Send an ACK to resynchronize and drop any data.
1848 * But keep on processing for RST or ACK.
1849 */
1850 tp->t_flags |= TF_ACKNOW;
1851 todrop = tlen;
1852 tcpstat.tcps_rcvduppack++;
1853 tcpstat.tcps_rcvdupbyte += todrop;
1854 } else {
1855 tcpstat.tcps_rcvpartduppack++;
1856 tcpstat.tcps_rcvpartdupbyte += todrop;
1857 }
1858 drop_hdrlen += todrop; /* drop from the top afterwards */
1859 th->th_seq += todrop;
1860 tlen -= todrop;
1861 if (th->th_urp > todrop)
1862 th->th_urp -= todrop;
1863 else {
1864 thflags &= ~TH_URG;
1865 th->th_urp = 0;
1866 }
1867 }
1868
1869 /*
1870 * If new data are received on a connection after the
1871 * user processes are gone, then RST the other end.
1872 */
1873 if ((so->so_state & SS_NOFDREF) &&
1874 tp->t_state > TCPS_CLOSE_WAIT && tlen) {
1875 tp = tcp_close(tp);
1876 tcpstat.tcps_rcvafterclose++;
1877 rstreason = BANDLIM_UNLIMITED;
1878 goto dropwithreset;
1879 }
1880
1881 /*
1882 * If segment ends after window, drop trailing data
1883 * (and PUSH and FIN); if nothing left, just ACK.
1884 */
61896e3c 1885 todrop = (th->th_seq + tlen) - (tp->rcv_nxt + tp->rcv_wnd);
984263bc
MD
1886 if (todrop > 0) {
1887 tcpstat.tcps_rcvpackafterwin++;
1888 if (todrop >= tlen) {
1889 tcpstat.tcps_rcvbyteafterwin += tlen;
1890 /*
1891 * If a new connection request is received
1892 * while in TIME_WAIT, drop the old connection
1893 * and start over if the sequence numbers
1894 * are above the previous ones.
1895 */
1896 if (thflags & TH_SYN &&
1897 tp->t_state == TCPS_TIME_WAIT &&
1898 SEQ_GT(th->th_seq, tp->rcv_nxt)) {
1899 tp = tcp_close(tp);
1900 goto findpcb;
1901 }
1902 /*
1903 * If window is closed can only take segments at
1904 * window edge, and have to drop data and PUSH from
1905 * incoming segments. Continue processing, but
1906 * remember to ack. Otherwise, drop segment
1907 * and ack.
1908 */
1909 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) {
1910 tp->t_flags |= TF_ACKNOW;
1911 tcpstat.tcps_rcvwinprobe++;
1912 } else
1913 goto dropafterack;
1914 } else
1915 tcpstat.tcps_rcvbyteafterwin += todrop;
1916 m_adj(m, -todrop);
1917 tlen -= todrop;
61896e3c 1918 thflags &= ~(TH_PUSH | TH_FIN);
984263bc
MD
1919 }
1920
1921 /*
1922 * If last ACK falls within this segment's sequence numbers,
1923 * record its timestamp.
ad0af98b
ND
1924 * NOTE:
1925 * 1) That the test incorporates suggestions from the latest
1926 * proposal of the tcplw@cray.com list (Braden 1993/04/26).
1927 * 2) That updating only on newer timestamps interferes with
1928 * our earlier PAWS tests, so this check should be solely
1929 * predicated on the sequence space of this segment.
1930 * 3) That we modify the segment boundary check to be
1931 * Last.ACK.Sent <= SEG.SEQ + SEG.LEN
1932 * instead of RFC1323's
1933 * Last.ACK.Sent < SEG.SEQ + SEG.LEN,
1934 * This modified check allows us to overcome RFC1323's
1935 * limitations as described in Stevens TCP/IP Illustrated
1936 * Vol. 2 p.869. In such cases, we can still calculate the
1937 * RTT correctly when RCV.NXT == Last.ACK.Sent.
984263bc 1938 */
ad0af98b
ND
1939 if ((to.to_flags & TOF_TS) && SEQ_LEQ(th->th_seq, tp->last_ack_sent) &&
1940 SEQ_LEQ(tp->last_ack_sent, (th->th_seq + tlen
1941 + ((thflags & TH_SYN) != 0)
1942 + ((thflags & TH_FIN) != 0)))) {
984263bc
MD
1943 tp->ts_recent_age = ticks;
1944 tp->ts_recent = to.to_tsval;
1945 }
1946
1947 /*
1948 * If a SYN is in the window, then this is an
1949 * error and we send an RST and drop the connection.
1950 */
1951 if (thflags & TH_SYN) {
1952 tp = tcp_drop(tp, ECONNRESET);
1953 rstreason = BANDLIM_UNLIMITED;
1954 goto dropwithreset;
1955 }
1956
1957 /*
1958 * If the ACK bit is off: if in SYN-RECEIVED state or SENDSYN
1959 * flag is on (half-synchronized state), then queue data for
1960 * later processing; else drop segment and return.
1961 */
61896e3c 1962 if (!(thflags & TH_ACK)) {
984263bc
MD
1963 if (tp->t_state == TCPS_SYN_RECEIVED ||
1964 (tp->t_flags & TF_NEEDSYN))
1965 goto step6;
1966 else
1967 goto drop;
1968 }
1969
1970 /*
1971 * Ack processing.
1972 */
1973 switch (tp->t_state) {
984263bc 1974 /*
91489f6b 1975 * In SYN_RECEIVED state, the ACK acknowledges our SYN, so enter
984263bc
MD
1976 * ESTABLISHED state and continue processing.
1977 * The ACK was checked above.
1978 */
1979 case TCPS_SYN_RECEIVED:
1980
1981 tcpstat.tcps_connects++;
1982 soisconnected(so);
1983 /* Do window scaling? */
61896e3c 1984 if ((tp->t_flags & (TF_RCVD_SCALE | TF_REQ_SCALE)) ==
df1d2774 1985 (TF_RCVD_SCALE | TF_REQ_SCALE))
984263bc 1986 tp->rcv_scale = tp->request_r_scale;
984263bc 1987 /*
984263bc
MD
1988 * Make transitions:
1989 * SYN-RECEIVED -> ESTABLISHED
1990 * SYN-RECEIVED* -> FIN-WAIT-1
1991 */
1992 tp->t_starttime = ticks;
1993 if (tp->t_flags & TF_NEEDFIN) {
1994 tp->t_state = TCPS_FIN_WAIT_1;
1995 tp->t_flags &= ~TF_NEEDFIN;
1996 } else {
8651f7f8 1997 tcp_established(tp);
984263bc
MD
1998 }
1999 /*
2000 * If segment contains data or ACK, will call tcp_reass()
2001 * later; if not, do so now to pass queued data to user.
2002 */
61896e3c 2003 if (tlen == 0 && !(thflags & TH_FIN))
f23061d4 2004 tcp_reass(tp, NULL, NULL, NULL);
984263bc
MD
2005 /* fall into ... */
2006
2007 /*
2008 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range
2009 * ACKs. If the ack is in the range
2010 * tp->snd_una < th->th_ack <= tp->snd_max
2011 * then advance tp->snd_una to th->th_ack and drop
2012 * data from the retransmission queue. If this ACK reflects
2013 * more up to date window information we update our window information.
2014 */
2015 case TCPS_ESTABLISHED:
2016 case TCPS_FIN_WAIT_1:
2017 case TCPS_FIN_WAIT_2:
2018 case TCPS_CLOSE_WAIT:
2019 case TCPS_CLOSING:
2020 case TCPS_LAST_ACK:
2021 case TCPS_TIME_WAIT:
2022
2023 if (SEQ_LEQ(th->th_ack, tp->snd_una)) {
942d88ef
SZ
2024 boolean_t maynotdup = FALSE;
2025
91489f6b
JH
2026 if (TCP_DO_SACK(tp))
2027 tcp_sack_update_scoreboard(tp, &to);
942d88ef
SZ
2028
2029 if (tlen != 0 || tiwin != tp->snd_wnd ||
2030 ((thflags & TH_FIN) && !(tp->t_flags & TF_SAWFIN)))
2031 maynotdup = TRUE;
2032
a48c5dd5 2033 if (!tcp_callout_active(tp, tp->tt_rexmt) ||
91489f6b 2034 th->th_ack != tp->snd_una) {
942d88ef 2035 if (!maynotdup)
52f9ffcf 2036 tcpstat.tcps_rcvdupack++;
91489f6b
JH
2037 tp->t_dupacks = 0;
2038 break;
2039 }
942d88ef
SZ
2040
2041#define DELAY_DUPACK \
2042do { \
2043 delayed_dupack = TRUE; \
2044 th_dupack = th->th_ack; \
2045 to_flags = to.to_flags; \
2046} while (0)
2047 if (maynotdup) {
859bc3f7 2048 if (!tcp_do_rfc6675 ||
ffe35e17
SZ
2049 !TCP_DO_SACK(tp) ||
2050 (to.to_flags &
2051 (TOF_SACK | TOF_SACK_REDUNDANT))
2052 != TOF_SACK) {
2053 tp->t_dupacks = 0;
91489f6b 2054 } else {
942d88ef 2055 DELAY_DUPACK;
91489f6b 2056 }
95b22adf 2057 break;
95b22adf 2058 }
942d88ef
SZ
2059 if ((thflags & TH_FIN) && !(tp->t_flags & TF_QUEDFIN)) {
2060 /*
2061 * This could happen, if the reassemable
2062 * queue overflew or was drained. Don't
2063 * drop this FIN here; defer the duplicated
2064 * ACK processing until this FIN gets queued.
2065 */
2066 DELAY_DUPACK;
2067 break;
2068 }
2069#undef DELAY_DUPACK
2070
0a832381 2071 if (tcp_recv_dupack(tp, th->th_ack, to.to_flags))
ffe35e17 2072 goto drop;
27f4bf33
SZ
2073 else
2074 break;
984263bc
MD
2075 }
2076
2077 KASSERT(SEQ_GT(th->th_ack, tp->snd_una), ("th_ack <= snd_una"));
984263bc
MD
2078 tp->t_dupacks = 0;
2079 if (SEQ_GT(th->th_ack, tp->snd_max)) {
5a274421
JH
2080 /*
2081 * Detected optimistic ACK attack.
2082 * Force slow-start to de-synchronize attack.
2083 */
2084 tp->snd_cwnd = tp->t_maxseg;
8acdb67c 2085 tp->snd_wacked = 0;
5a274421 2086
984263bc
MD
2087 tcpstat.tcps_rcvacktoomuch++;
2088 goto dropafterack;
2089 }
2090 /*
2091 * If we reach this point, ACK is not a duplicate,
2092 * i.e., it ACKs something we sent.
2093 */
2094 if (tp->t_flags & TF_NEEDSYN) {
2095 /*
2096 * T/TCP: Connection was half-synchronized, and our
2097 * SYN has been ACK'd (so connection is now fully
2098 * synchronized). Go to non-starred state,
2099 * increment snd_una for ACK of SYN, and check if
2100 * we can do window scaling.
2101 */
2102 tp->t_flags &= ~TF_NEEDSYN;
2103 tp->snd_una++;
2104 /* Do window scaling? */
61896e3c 2105 if ((tp->t_flags & (TF_RCVD_SCALE | TF_REQ_SCALE)) ==
df1d2774 2106 (TF_RCVD_SCALE | TF_REQ_SCALE))
984263bc 2107 tp->rcv_scale = tp->request_r_scale;
984263bc
MD
2108 }
2109
2110process_ACK:
2111 acked = th->th_ack - tp->snd_una;
2112 tcpstat.tcps_rcvackpack++;
2113 tcpstat.tcps_rcvackbyte += acked;
2114
b5572302 2115 if (tcp_do_eifel_detect && acked > 0 &&
95b22adf 2116 (to.to_flags & TOF_TS) && (to.to_tsecr != 0) &&
1c8b7a61 2117 (tp->rxt_flags & TRXT_F_FIRSTACCACK)) {
bfdb979e
JH
2118 /* Eifel detection applicable. */
2119 if (to.to_tsecr < tp->t_rexmtTS) {
bfdb979e 2120 ++tcpstat.tcps_eifeldetected;
8819433a 2121 tcp_revert_congestion_state(tp);
928c3291 2122 if (tp->t_rxtshift != 1 ||
8819433a
JH
2123 ticks >= tp->t_badrxtwin)
2124 ++tcpstat.tcps_rttcantdetect;
bfdb979e
JH
2125 }
2126 } else if (tp->t_rxtshift == 1 && ticks < tp->t_badrxtwin) {
b5572302
JH
2127 /*
2128 * If we just performed our first retransmit,
2129 * and the ACK arrives within our recovery window,
2130 * then it was a mistake to do the retransmit
91489f6b 2131 * in the first place. Recover our original cwnd
b5572302
JH
2132 * and ssthresh, and proceed to transmit where we
2133 * left off.
2134 */
bfdb979e
JH
2135 tcp_revert_congestion_state(tp);
2136 ++tcpstat.tcps_rttdetected;
984263bc
MD
2137 }
2138
2139 /*
2140 * If we have a timestamp reply, update smoothed
2141 * round trip time. If no timestamp is present but
2142 * transmit timer is running and timed sequence
2143 * number was acked, update smoothed round trip time.
2144 * Since we now have an rtt measurement, cancel the
2145 * timer backoff (cf., Phil Karn's retransmit alg.).
2146 * Recompute the initial retransmit timer.
2147 *
2148 * Some machines (certain windows boxes) send broken
d24ce1dc 2149 * timestamp replies during the SYN+ACK phase, ignore
984263bc
MD
2150 * timestamps of 0.
2151 */
95b22adf 2152 if ((to.to_flags & TOF_TS) && (to.to_tsecr != 0))
073ec6c4 2153 tcp_xmit_timer(tp, ticks - to.to_tsecr + 1, th->th_ack);
95b22adf 2154 else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq))
073ec6c4 2155 tcp_xmit_timer(tp, ticks - tp->t_rtttime, th->th_ack);
984263bc
MD
2156 tcp_xmit_bandwidth_limit(tp, th->th_ack);
2157
2158 /*
984263bc
MD
2159 * If no data (only SYN) was ACK'd,
2160 * skip rest of ACK processing.
2161 */
2162 if (acked == 0)
2163 goto step6;
2164
efd4b327 2165 /* Stop looking for an acceptable ACK since one was received. */
1c8b7a61
SZ
2166 tp->rxt_flags &= ~(TRXT_F_FIRSTACCACK |
2167 TRXT_F_FASTREXMT | TRXT_F_EARLYREXMT);
efd4b327 2168
6d49aa6f
MD
2169 if (acked > so->so_snd.ssb_cc) {
2170 tp->snd_wnd -= so->so_snd.ssb_cc;
2171 sbdrop(&so->so_snd.sb, (int)so->so_snd.ssb_cc);
61896e3c 2172 ourfinisacked = TRUE;
984263bc 2173 } else {
6d49aa6f 2174 sbdrop(&so->so_snd.sb, acked);
984263bc 2175 tp->snd_wnd -= acked;
61896e3c 2176 ourfinisacked = FALSE;
984263bc
MD
2177 }
2178 sowwakeup(so);
91489f6b
JH
2179
2180 /*
2181 * Update window information.
91489f6b 2182 */
e126661b 2183 if (acceptable_window_update(tp, th, tiwin)) {
91489f6b
JH
2184 /* keep track of pure window updates */
2185 if (tlen == 0 && tp->snd_wl2 == th->th_ack &&
2186 tiwin > tp->snd_wnd)
2187 tcpstat.tcps_rcvwinupd++;
2188 tp->snd_wnd = tiwin;
2189 tp->snd_wl1 = th->th_seq;
2190 tp->snd_wl2 = th->th_ack;
2191 if (tp->snd_wnd > tp->max_sndwnd)
2192 tp->max_sndwnd = tp->snd_wnd;
2193 needoutput = TRUE;
2194 }
2195
2196 tp->snd_una = th->th_ack;
2197 if (TCP_DO_SACK(tp))
2198 tcp_sack_update_scoreboard(tp, &to);
95b22adf 2199 if (IN_FASTRECOVERY(tp)) {
91489f6b 2200 if (SEQ_GEQ(th->th_ack, tp->snd_recover)) {
95b22adf 2201 EXIT_FASTRECOVERY(tp);
91489f6b
JH
2202 needoutput = TRUE;
2203 /*
2204 * If the congestion window was inflated
2205 * to account for the other side's
2206 * cached packets, retract it.
8acdb67c
JH
2207 */
2208 if (!TCP_DO_SACK(tp))
2209 tp->snd_cwnd = tp->snd_ssthresh;
2210
2211 /*
91489f6b
JH
2212 * Window inflation should have left us
2213 * with approximately snd_ssthresh outstanding
2214 * data. But, in case we would be inclined
2215 * to send a burst, better do it using
2216 * slow start.
2217 */
91489f6b
JH
2218 if (SEQ_GT(th->th_ack + tp->snd_cwnd,
2219 tp->snd_max + 2 * tp->t_maxseg))
2220 tp->snd_cwnd =
2221 (tp->snd_max - tp->snd_una) +
2222 2 * tp->t_maxseg;
8acdb67c
JH
2223
2224 tp->snd_wacked = 0;
91489f6b
JH
2225 } else {
2226 if (TCP_DO_SACK(tp)) {
2227 tp->snd_max_rexmt = tp->snd_max;
ccb518ea
SZ
2228 tcp_sack_rexmt(tp,
2229 tp->snd_una == tp->rexmt_high);
91489f6b
JH
2230 } else {
2231 tcp_newreno_partial_ack(tp, th, acked);
2232 }
2233 needoutput = FALSE;
2234 }
95b22adf 2235 } else {
91489f6b 2236 /*
8acdb67c
JH
2237 * Open the congestion window. When in slow-start,
2238 * open exponentially: maxseg per packet. Otherwise,
2239 * open linearly: maxseg per window.
91489f6b 2240 */
8acdb67c
JH
2241 if (tp->snd_cwnd <= tp->snd_ssthresh) {
2242 u_int abc_sslimit =
2243 (SEQ_LT(tp->snd_nxt, tp->snd_max) ?
2244 tp->t_maxseg : 2 * tp->t_maxseg);
2245
2246 /* slow-start */
2247 tp->snd_cwnd += tcp_do_abc ?
2248 min(acked, abc_sslimit) : tp->t_maxseg;
2249 } else {
2250 /* linear increase */
2251 tp->snd_wacked += tcp_do_abc ? acked :
2252 tp->t_maxseg;
2253 if (tp->snd_wacked >= tp->snd_cwnd) {
2254 tp->snd_wacked -= tp->snd_cwnd;
2255 tp->snd_cwnd += tp->t_maxseg;
2256 }
2257 }
2258 tp->snd_cwnd = min(tp->snd_cwnd,
2259 TCP_MAXWIN << tp->snd_scale);
95b22adf 2260 tp->snd_recover = th->th_ack - 1;
cfb3f3f4 2261 }
984263bc
MD
2262 if (SEQ_LT(tp->snd_nxt, tp->snd_una))
2263 tp->snd_nxt = tp->snd_una;
2264
91489f6b
JH
2265 /*
2266 * If all outstanding data is acked, stop retransmit
2267 * timer and remember to restart (more output or persist).
2268 * If there is more data to be acked, restart retransmit
2269 * timer, using current (possibly backed-off) value.
2270 */
2271 if (th->th_ack == tp->snd_max) {
a48c5dd5 2272 tcp_callout_stop(tp, tp->tt_rexmt);
91489f6b 2273 needoutput = TRUE;
a48c5dd5
SZ
2274 } else if (!tcp_callout_active(tp, tp->tt_persist)) {
2275 tcp_callout_reset(tp, tp->tt_rexmt, tp->t_rxtcur,
2276 tcp_timer_rexmt);
2277 }
91489f6b 2278
984263bc 2279 switch (tp->t_state) {
984263bc
MD
2280 /*
2281 * In FIN_WAIT_1 STATE in addition to the processing
2282 * for the ESTABLISHED state if our FIN is now acknowledged
2283 * then enter FIN_WAIT_2.
2284 */
2285 case TCPS_FIN_WAIT_1:
2286 if (ourfinisacked) {
2287 /*
2288 * If we can't receive any more
2289 * data, then closing user can proceed.
2290 * Starting the timer is contrary to the
2291 * specification, but if we don't get a FIN
2292 * we'll hang forever.
2293 */
2294 if (so->so_state & SS_CANTRCVMORE) {
2295 soisdisconnected(so);
a48c5dd5 2296 tcp_callout_reset(tp, tp->tt_2msl,
5d61ded3 2297 tp->t_maxidle, tcp_timer_2msl);
984263bc
MD
2298 }
2299 tp->t_state = TCPS_FIN_WAIT_2;
2300 }
2301 break;
2302
95b22adf 2303 /*
984263bc
MD
2304 * In CLOSING STATE in addition to the processing for
2305 * the ESTABLISHED state if the ACK acknowledges our FIN
2306 * then enter the TIME-WAIT state, otherwise ignore
2307 * the segment.
2308 */
2309 case TCPS_CLOSING:
2310 if (ourfinisacked) {
2311 tp->t_state = TCPS_TIME_WAIT;
2312 tcp_canceltimers(tp);
27b8aee3 2313 tcp_callout_reset(tp, tp->tt_2msl,
01d3427a
SZ
2314 2 * tcp_rmx_msl(tp),
2315 tcp_timer_2msl);
984263bc
MD
2316 soisdisconnected(so);
2317 }
2318 break;
2319
2320 /*
2321 * In LAST_ACK, we may still be waiting for data to drain
2322 * and/or to be acked, as well as for the ack of our FIN.
2323 * If our FIN is now acknowledged, delete the TCB,
2324 * enter the closed state and return.
2325 */
2326 case TCPS_LAST_ACK:
2327 if (ourfinisacked) {
2328 tp = tcp_close(tp);
2329 goto drop;
2330 }
2331 break;
2332
2333 /*
2334 * In TIME_WAIT state the only thing that should arrive
2335 * is a retransmission of the remote FIN. Acknowledge
2336 * it and restart the finack timer.
2337 */
2338 case TCPS_TIME_WAIT:
01d3427a 2339 tcp_callout_reset(tp, tp->tt_2msl, 2 * tcp_rmx_msl(tp),
a48c5dd5 2340 tcp_timer_2msl);
984263bc
MD
2341 goto dropafterack;
2342 }
2343 }
2344
2345step6:
2346 /*
2347 * Update window information.
2348 * Don't look at window if no ACK: TAC's send garbage on first SYN.
2349 */
2350 if ((thflags & TH_ACK) &&
df9d7670 2351 acceptable_window_update(tp, th, tiwin)) {
984263bc 2352 /* keep track of pure window updates */
b5572302
JH
2353 if (tlen == 0 && tp->snd_wl2 == th->th_ack &&
2354 tiwin > tp->snd_wnd)
984263bc
MD
2355 tcpstat.tcps_rcvwinupd++;
2356 tp->snd_wnd = tiwin;
2357 tp->snd_wl1 = th->th_seq;
2358 tp->snd_wl2 = th->th_ack;
2359 if (tp->snd_wnd > tp->max_sndwnd)
2360 tp->max_sndwnd = tp->snd_wnd;
61896e3c 2361 needoutput = TRUE;
984263bc
MD
2362 }
2363
2364 /*
2365 * Process segments with URG.
2366 */
2367 if ((thflags & TH_URG) && th->th_urp &&
95b22adf 2368 !TCPS_HAVERCVDFIN(tp->t_state)) {
984263bc
MD
2369 /*
2370 * This is a kludge, but if we receive and accept
2371 * random urgent pointers, we'll crash in
2372 * soreceive. It's hard to imagine someone
2373 * actually wanting to send this much urgent data.
2374 */
6d49aa6f 2375 if (th->th_urp + so->so_rcv.ssb_cc > sb_max) {
984263bc
MD
2376 th->th_urp = 0; /* XXX */
2377 thflags &= ~TH_URG; /* XXX */
2378 goto dodata; /* XXX */
2379 }
2380 /*
2381 * If this segment advances the known urgent pointer,
2382 * then mark the data stream. This should not happen
2383 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since
2384 * a FIN has been received from the remote side.
2385 * In these states we ignore the URG.
2386 *
2387 * According to RFC961 (Assigned Protocols),
2388 * the urgent pointer points to the last octet
2389 * of urgent data. We continue, however,
2390 * to consider it to indicate the first octet
2391 * of data past the urgent section as the original
2392 * spec states (in one of two places).
2393 */
61896e3c 2394 if (SEQ_GT(th->th_seq + th->th_urp, tp->rcv_up)) {
984263bc 2395 tp->rcv_up = th->th_seq + th->th_urp;
6d49aa6f 2396 so->so_oobmark = so->so_rcv.ssb_cc +
984263bc
MD
2397 (tp->rcv_up - tp->rcv_nxt) - 1;
2398 if (so->so_oobmark == 0)
6cef7136 2399 sosetstate(so, SS_RCVATMARK);
984263bc
MD
2400 sohasoutofband(so);
2401 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA);
2402 }
2403 /*
2404 * Remove out of band data so doesn't get presented to user.
2405 * This can happen independent of advancing the URG pointer,
2406 * but if two URG's are pending at once, some out-of-band
2407 * data may creep in... ick.
2408 */
61896e3c
JH
2409 if (th->th_urp <= (u_long)tlen &&
2410 !(so->so_options & SO_OOBINLINE)) {
2411 /* hdr drop is delayed */
2412 tcp_pulloutofband(so, th, m, drop_hdrlen);
2413 }
984263bc
MD
2414 } else {
2415 /*
2416 * If no out of band data is expected,
2417 * pull receive urgent pointer along
2418 * with the receive window.
2419 */
2420 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up))
2421 tp->rcv_up = tp->rcv_nxt;
2422 }
984263bc 2423
61896e3c 2424dodata: /* XXX */
984263bc
MD
2425 /*
2426 * Process the segment text, merging it into the TCP sequencing queue,
2427 * and arranging for acknowledgment of receipt if necessary.
2428 * This process logically involves adjusting tp->rcv_wnd as data
2429 * is presented to the user (this happens in tcp_usrreq.c,
2430 * case PRU_RCVD). If a FIN has already been received on this
2431 * connection then we just ignore the text.
2432 */
95b22adf 2433 if ((tlen || (thflags & TH_FIN)) && !TCPS_HAVERCVDFIN(tp->t_state)) {
942d88ef
SZ
2434 if (thflags & TH_FIN)
2435 tp->t_flags |= TF_SAWFIN;
984263bc
MD
2436 m_adj(m, drop_hdrlen); /* delayed header drop */
2437 /*
2438 * Insert segment which includes th into TCP reassembly queue
2439 * with control block tp. Set thflags to whether reassembly now
2440 * includes a segment with FIN. This handles the common case
2441 * inline (segment is the next to be received on an established
2442 * connection, and the queue is empty), avoiding linkage into
2443 * and removal from the queue and repetition of various
2444 * conversions.
2445 * Set DELACK for segments received in order, but ack
2446 * immediately when segments are out of order (so
2447 * fast retransmit can work).
2448 */
2449 if (th->th_seq == tp->rcv_nxt &&
0f9e45de 2450 TAILQ_EMPTY(&tp->t_segq) &&
984263bc 2451 TCPS_HAVEESTABLISHED(tp->t_state)) {
942d88ef
SZ
2452 if (thflags & TH_FIN)
2453 tp->t_flags |= TF_QUEDFIN;
a48c5dd5
SZ
2454 if (DELAY_ACK(tp)) {
2455 tcp_callout_reset(tp, tp->tt_delack,
2456 tcp_delacktime, tcp_timer_delack);
2457 } else {
984263bc 2458 tp->t_flags |= TF_ACKNOW;
a48c5dd5 2459 }
984263bc
MD
2460 tp->rcv_nxt += tlen;
2461 thflags = th->th_flags & TH_FIN;
2462 tcpstat.tcps_rcvpack++;
2463 tcpstat.tcps_rcvbyte += tlen;
2464 ND6_HINT(tp);
6cef7136 2465 if (so->so_state & SS_CANTRCVMORE) {
984263bc 2466 m_freem(m);
6cef7136
MD
2467 } else {
2468 lwkt_gettoken(&so->so_rcv.ssb_token);
6d49aa6f 2469 ssb_appendstream(&so->so_rcv, m);
6cef7136
MD
2470 lwkt_reltoken(&so->so_rcv.ssb_token);
2471 }
984263bc
MD
2472 sorwakeup(so);
2473 } else {
c7e6499a 2474 if (!(tp->sack_flags & TSACK_F_DUPSEG)) {
91489f6b
JH
2475 /* Initialize SACK report block. */
2476 tp->reportblk.rblk_start = th->th_seq;
3a5d999b
SZ
2477 tp->reportblk.rblk_end = TCP_SACK_BLKEND(
2478 th->th_seq + tlen, thflags);
91489f6b 2479 }
984263bc
MD
2480 thflags = tcp_reass(tp, th, &tlen, m);
2481 tp->t_flags |= TF_ACKNOW;
2482 }
2483
2484 /*
2485 * Note the amount of data that peer has sent into
2486 * our window, in order to estimate the sender's
2487 * buffer size.
2488 */
6d49aa6f 2489 len = so->so_rcv.ssb_hiwat - (tp->rcv_adv - tp->rcv_nxt);
984263bc
MD
2490 } else {
2491 m_freem(m);
2492 thflags &= ~TH_FIN;
2493 }
2494
2495 /*
2496 * If FIN is received ACK the FIN and let the user know
2497 * that the connection is closing.
2498 */
2499 if (thflags & TH_FIN) {
95b22adf 2500 if (!TCPS_HAVERCVDFIN(tp->t_state)) {
984263bc
MD
2501 socantrcvmore(so);
2502 /*
2503 * If connection is half-synchronized
2504 * (ie NEEDSYN flag on) then delay ACK,
2505 * so it may be piggybacked when SYN is sent.
2506 * Otherwise, since we received a FIN then no
2507 * more input can be expected, send ACK now.
2508 */
a48c5dd5
SZ
2509 if (DELAY_ACK(tp) && (tp->t_flags & TF_NEEDSYN)) {
2510 tcp_callout_reset(tp, tp->tt_delack,
2511 tcp_delacktime, tcp_timer_delack);
2512 } else {
984263bc 2513 tp->t_flags |= TF_ACKNOW;
a48c5dd5 2514 }
984263bc
MD
2515 tp->rcv_nxt++;
2516 }
984263bc 2517
61896e3c 2518 switch (tp->t_state) {
95b22adf 2519 /*
984263bc
MD
2520 * In SYN_RECEIVED and ESTABLISHED STATES
2521 * enter the CLOSE_WAIT state.
2522 */
2523 case TCPS_SYN_RECEIVED:
2524 tp->t_starttime = ticks;
2525 /*FALLTHROUGH*/
2526 case TCPS_ESTABLISHED:
2527 tp->t_state = TCPS_CLOSE_WAIT;
2528 break;
2529
95b22adf 2530 /*
984263bc
MD
2531 * If still in FIN_WAIT_1 STATE FIN has not been acked so
2532 * enter the CLOSING state.
2533 */
2534 case TCPS_FIN_WAIT_1:
2535 tp->t_state = TCPS_CLOSING;
2536 break;
2537
95b22adf 2538 /*
984263bc
MD
2539 * In FIN_WAIT_2 state enter the TIME_WAIT state,
2540 * starting the time-wait timer, turning off the other
2541 * standard timers.
2542 */
2543 case TCPS_FIN_WAIT_2:
2544 tp->t_state = TCPS_TIME_WAIT;
2545 tcp_canceltimers(tp);
01d3427a 2546 tcp_callout_reset(tp, tp->tt_2msl, 2 * tcp_rmx_msl(tp),
a48c5dd5 2547 tcp_timer_2msl);
984263bc
MD
2548 soisdisconnected(so);
2549 break;
2550
2551 /*
2552 * In TIME_WAIT state restart the 2 MSL time_wait timer.
2553 */
2554 case TCPS_TIME_WAIT:
01d3427a 2555 tcp_callout_reset(tp, tp->tt_2msl, 2 * tcp_rmx_msl(tp),
a48c5dd5 2556 tcp_timer_2msl);
984263bc
MD
2557 break;
2558 }
2559 }
61896e3c 2560
984263bc
MD
2561#ifdef TCPDEBUG
2562 if (so->so_options & SO_DEBUG)
f23061d4 2563 tcp_trace(TA_INPUT, ostate, tp, tcp_saveipgen, &tcp_savetcp, 0);
984263bc
MD
2564#endif
2565
2566 /*
27f4bf33
SZ
2567 * Delayed duplicated ACK processing
2568 */
0a832381 2569 if (delayed_dupack && tcp_recv_dupack(tp, th_dupack, to_flags))
27f4bf33
SZ
2570 needoutput = FALSE;
2571
2572 /*
984263bc
MD
2573 * Return any desired output.
2574 */
2575 if (needoutput || (tp->t_flags & TF_ACKNOW))
f23061d4 2576 tcp_output(tp);
d58ca578 2577 tcp_sack_report_cleanup(tp);
002c1265 2578 return(IPPROTO_DONE);
984263bc
MD
2579
2580dropafterack:
2581 /*
2582 * Generate an ACK dropping incoming segment if it occupies
2583 * sequence space, where the ACK reflects our state.
2584 *
2585 * We can now skip the test for the RST flag since all
2586 * paths to this code happen after packets containing
2587 * RST have been dropped.
2588 *
2589 * In the SYN-RECEIVED state, don't send an ACK unless the
2590 * segment we received passes the SYN-RECEIVED ACK test.
2591 * If it fails send a RST. This breaks the loop in the
2592 * "LAND" DoS attack, and also prevents an ACK storm
2593 * between two listening ports that have been sent forged
2594 * SYN segments, each with the source address of the other.
2595 */
2596 if (tp->t_state == TCPS_SYN_RECEIVED && (thflags & TH_ACK) &&
2597 (SEQ_GT(tp->snd_una, th->th_ack) ||
2598 SEQ_GT(th->th_ack, tp->snd_max)) ) {
2599 rstreason = BANDLIM_RST_OPENPORT;
2600 goto dropwithreset;
2601 }
2602#ifdef TCPDEBUG
2603 if (so->so_options & SO_DEBUG)
f23061d4 2604 tcp_trace(TA_DROP, ostate, tp, tcp_saveipgen, &tcp_savetcp, 0);
984263bc
MD
2605#endif
2606 m_freem(m);
2607 tp->t_flags |= TF_ACKNOW;
f23061d4 2608 tcp_output(tp);
d58ca578 2609 tcp_sack_report_cleanup(tp);
002c1265 2610 return(IPPROTO_DONE);
984263bc
MD
2611
2612dropwithreset:
2613 /*
2614 * Generate a RST, dropping incoming segment.
2615 * Make ACK acceptable to originator of segment.
2616 * Don't bother to respond if destination was broadcast/multicast.
2617 */
61896e3c 2618 if ((thflags & TH_RST) || m->m_flags & (M_BCAST | M_MCAST))
984263bc
MD
2619 goto drop;
2620 if (isipv6) {
2621 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
2622 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src))
2623 goto drop;
2624 } else {
2625 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) ||
2626 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
95b22adf
JH
2627 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) ||
2628 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif))
984263bc
MD
2629 goto drop;
2630 }
2631 /* IPv6 anycast check is done at tcp6_input() */
2632
2633 /*
2634 * Perform bandwidth limiting.
2635 */
2636#ifdef ICMP_BANDLIM
2637 if (badport_bandlim(rstreason) < 0)
2638 goto drop;
2639#endif
2640
2641#ifdef TCPDEBUG
2642 if (tp == NULL || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
f23061d4 2643 tcp_trace(TA_DROP, ostate, tp, tcp_saveipgen, &tcp_savetcp, 0);
984263bc
MD
2644#endif
2645 if (thflags & TH_ACK)
2646 /* mtod() below is safe as long as hdr dropping is delayed */
2647 tcp_respond(tp, mtod(m, void *), th, m, (tcp_seq)0, th->th_ack,
2648 TH_RST);
2649 else {
2650 if (thflags & TH_SYN)
2651 tlen++;
2652 /* mtod() below is safe as long as hdr dropping is delayed */
61896e3c
JH
2653 tcp_respond(tp, mtod(m, void *), th, m, th->th_seq + tlen,
2654 (tcp_seq)0, TH_RST | TH_ACK);
984263bc 2655 }
d58ca578
SZ
2656 if (tp != NULL)
2657 tcp_sack_report_cleanup(tp);
002c1265 2658 return(IPPROTO_DONE);
984263bc
MD
2659
2660drop:
2661 /*
2662 * Drop space held by incoming segment and return.
2663 */
2664#ifdef TCPDEBUG
2665 if (tp == NULL || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
f23061d4 2666 tcp_trace(TA_DROP, ostate, tp, tcp_saveipgen, &tcp_savetcp, 0);
984263bc
MD
2667#endif
2668 m_freem(m);
d58ca578
SZ
2669 if (tp != NULL)
2670 tcp_sack_report_cleanup(tp);
002c1265 2671 return(IPPROTO_DONE);
984263bc
MD
2672}
2673
2674/*
2675 * Parse TCP options and place in tcpopt.
2676 */
2677static void
6c1bbf57
SZ
2678tcp_dooptions(struct tcpopt *to, u_char *cp, int cnt, boolean_t is_syn,
2679 tcp_seq ack)
984263bc 2680{
91489f6b 2681 int opt, optlen, i;
984263bc
MD
2682
2683 to->to_flags = 0;
2684 for (; cnt > 0; cnt -= optlen, cp += optlen) {
2685 opt = cp[0];
2686 if (opt == TCPOPT_EOL)
2687 break;
2688 if (opt == TCPOPT_NOP)
2689 optlen = 1;
2690 else {
2691 if (cnt < 2)
2692 break;
2693 optlen = cp[1];
2694 if (optlen < 2 || optlen > cnt)
2695 break;
2696 }
2697 switch (opt) {
2698 case TCPOPT_MAXSEG:
2699 if (optlen != TCPOLEN_MAXSEG)
2700 continue;
2701 if (!is_syn)
2702 continue;
2703 to->to_flags |= TOF_MSS;
407e896e 2704 bcopy(cp + 2, &to->to_mss, sizeof to->to_mss);
984263bc
MD
2705 to->to_mss = ntohs(to->to_mss);
2706 break;
2707 case TCPOPT_WINDOW:
2708 if (optlen != TCPOLEN_WINDOW)
2709 continue;
95b22adf 2710 if (!is_syn)
984263bc
MD
2711 continue;
2712 to->to_flags |= TOF_SCALE;
2713 to->to_requested_s_scale = min(cp[2], TCP_MAX_WINSHIFT);
2714 break;
2715 case TCPOPT_TIMESTAMP:
2716 if (optlen != TCPOLEN_TIMESTAMP)
2717 continue;
2718 to->to_flags |= TOF_TS;
407e896e 2719 bcopy(cp + 2, &to->to_tsval, sizeof to->to_tsval);
984263bc 2720 to->to_tsval = ntohl(to->to_tsval);
407e896e 2721 bcopy(cp + 6, &to->to_tsecr, sizeof to->to_tsecr);
984263bc 2722 to->to_tsecr = ntohl(to->to_tsecr);
ad0af98b
ND
2723 /*
2724 * If echoed timestamp is later than the current time,
2725 * fall back to non RFC1323 RTT calculation.
2726 */
2727 if (to->to_tsecr != 0 && TSTMP_GT(to->to_tsecr, ticks))
2728 to->to_tsecr = 0;
984263bc 2729 break;
91489f6b
JH
2730 case TCPOPT_SACK_PERMITTED:
2731 if (optlen != TCPOLEN_SACK_PERMITTED)
2732 continue;
2733 if (!is_syn)
2734 continue;
2735 to->to_flags |= TOF_SACK_PERMITTED;
2736 break;
2737 case TCPOPT_SACK:
2738 if ((optlen - 2) & 0x07) /* not multiple of 8 */
2739 continue;
2740 to->to_nsackblocks = (optlen - 2) / 8;
2741 to->to_sackblocks = (struct raw_sackblock *) (cp + 2);
2742 to->to_flags |= TOF_SACK;
2743 for (i = 0; i < to->to_nsackblocks; i++) {
2744 struct raw_sackblock *r = &to->to_sackblocks[i];
2745
2746 r->rblk_start = ntohl(r->rblk_start);
2747 r->rblk_end = ntohl(r->rblk_end);
865b0477
SZ
2748
2749 if (SEQ_LEQ(r->rblk_end, r->rblk_start)) {
2750 /*
2751 * Invalid SACK block; discard all
2752 * SACK blocks
2753 */
02cc2f35 2754 tcpstat.tcps_rcvbadsackopt++;
865b0477
SZ
2755 to->to_nsackblocks = 0;
2756 to->to_sackblocks = NULL;
2757 to->to_flags &= ~TOF_SACK;
2758 break;
2759 }
91489f6b 2760 }
6c1bbf57
SZ
2761 if ((to->to_flags & TOF_SACK) &&
2762 tcp_sack_ndsack_blocks(to->to_sackblocks,
2763 to->to_nsackblocks, ack))
2764 to->to_flags |= TOF_DSACK;
91489f6b 2765 break;
b1992928
MD
2766#ifdef TCP_SIGNATURE
2767 /*
2768 * XXX In order to reply to a host which has set the
2769 * TCP_SIGNATURE option in its initial SYN, we have to
2770 * record the fact that the option was observed here
2771 * for the syncache code to perform the correct response.
2772 */
2773 case TCPOPT_SIGNATURE:
2774 if (optlen != TCPOLEN_SIGNATURE)
2775 continue;
2776 to->to_flags |= (TOF_SIGNATURE | TOF_SIGLEN);
2777 break;
2778#endif /* TCP_SIGNATURE */
984263bc
MD
2779 default:
2780 continue;
2781 }
2782 }
2783}
2784
2785/*
2786 * Pull out of band byte out of a segment so
2787 * it doesn't appear in the user's data queue.
2788 * It is still reflected in the segment length for
2789 * sequencing purposes.
95b22adf 2790 * "off" is the delayed to be dropped hdrlen.
984263bc
MD
2791 */
2792static void
95b22adf 2793tcp_pulloutofband(struct socket *so, struct tcphdr *th, struct mbuf *m, int off)
984263bc
MD
2794{
2795 int cnt = off + th->th_urp - 1;
2796
2797 while (cnt >= 0) {
2798 if (m->m_len > cnt) {
2799 char *cp = mtod(m, caddr_t) + cnt;
2800 struct tcpcb *tp = sototcpcb(so);
2801
2802 tp->t_iobc = *cp;
2803 tp->t_oobflags |= TCPOOB_HAVEDATA;
95b22adf 2804 bcopy(cp + 1, cp, m->m_len - cnt - 1);
984263bc
MD
2805 m->m_len--;
2806 if (m->m_flags & M_PKTHDR)
2807 m->m_pkthdr.len--;
2808 return;
2809 }
2810 cnt -= m->m_len;
2811 m = m->m_next;
4090d6ff 2812 if (m == NULL)
984263bc
MD
2813 break;
2814 }
2815 panic("tcp_pulloutofband");
2816}
2817
2818/*
2819 * Collect new round-trip time estimate
2820 * and update averages and current timeout.
2821 */
2822static void
073ec6c4 2823tcp_xmit_timer(struct tcpcb *tp, int rtt, tcp_seq ack)
984263bc 2824{
073ec6c4 2825 int rebaserto = 0;
984263bc
MD
2826
2827 tcpstat.tcps_rttupdated++;
2828 tp->t_rttupdated++;
1c8b7a61
SZ
2829 if ((tp->rxt_flags & TRXT_F_REBASERTO) &&
2830 SEQ_GT(ack, tp->snd_max_prev)) {
073ec6c4
SZ
2831#ifdef DEBUG_EIFEL_RESPONSE
2832 kprintf("srtt/rttvar, prev %d/%d, cur %d/%d, ",
2833 tp->t_srtt_prev, tp->t_rttvar_prev,
2834 tp->t_srtt, tp->t_rttvar);
2835#endif
2836
2837 tcpstat.tcps_eifelresponse++;
2838 rebaserto = 1;
1c8b7a61 2839 tp->rxt_flags &= ~TRXT_F_REBASERTO;
073ec6c4
SZ
2840 tp->t_srtt = max(tp->t_srtt_prev, (rtt << TCP_RTT_SHIFT));
2841 tp->t_rttvar = max(tp->t_rttvar_prev,
2842 (rtt << (TCP_RTTVAR_SHIFT - 1)));
2843 if (tp->t_rttbest > tp->t_srtt + tp->t_rttvar)
2844 tp->t_rttbest = tp->t_srtt + tp->t_rttvar;
2845
2846#ifdef DEBUG_EIFEL_RESPONSE
2847 kprintf("new %d/%d ", tp->t_srtt, tp->t_rttvar);
2848#endif
2849 } else if (tp->t_srtt != 0) {
2850 int delta;
2851
984263bc
MD
2852 /*
2853 * srtt is stored as fixed point with 5 bits after the
2854 * binary point (i.e., scaled by 8). The following magic
2855 * is equivalent to the smoothing algorithm in rfc793 with
2856 * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed
2857 * point). Adjust rtt to origin 0.
2858 */
2859 delta = ((rtt - 1) << TCP_DELTA_SHIFT)
2860 - (tp->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT));
2861
2862 if ((tp->t_srtt += delta) <= 0)
2863 tp->t_srtt = 1;
2864
2865 /*
2866 * We accumulate a smoothed rtt variance (actually, a
2867 * smoothed mean difference), then set the retransmit
2868 * timer to smoothed rtt + 4 times the smoothed variance.
2869 * rttvar is stored as fixed point with 4 bits after the
2870 * binary point (scaled by 16). The following is
2871 * equivalent to rfc793 smoothing with an alpha of .75
2872 * (rttvar = rttvar*3/4 + |delta| / 4). This replaces
2873 * rfc793's wired-in beta.
2874 */
2875 if (delta < 0)
2876 delta = -delta;
2877 delta -= tp->t_rttvar >> (TCP_RTTVAR_SHIFT - TCP_DELTA_SHIFT);
2878 if ((tp->t_rttvar += delta) <= 0)
2879 tp->t_rttvar = 1;
2880 if (tp->t_rttbest > tp->t_srtt + tp->t_rttvar)
2881 tp->t_rttbest = tp->t_srtt + tp->t_rttvar;
2882 } else {
2883 /*
2884 * No rtt measurement yet - use the unsmoothed rtt.
2885 * Set the variance to half the rtt (so our first
2886 * retransmit happens at 3*rtt).
2887 */
2888 tp->t_srtt = rtt << TCP_RTT_SHIFT;
2889 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1);
2890 tp->t_rttbest = tp->t_srtt + tp->t_rttvar;
2891 }
2892 tp->t_rtttime = 0;
2893 tp->t_rxtshift = 0;
2894
073ec6c4
SZ
2895#ifdef DEBUG_EIFEL_RESPONSE
2896 if (rebaserto) {
2897 kprintf("| rxtcur prev %d, old %d, ",
2898 tp->t_rxtcur_prev, tp->t_rxtcur);
2899 }
2900#endif
2901
984263bc
MD
2902 /*
2903 * the retransmit should happen at rtt + 4 * rttvar.
2904 * Because of the way we do the smoothing, srtt and rttvar
2905 * will each average +1/2 tick of bias. When we compute
2906 * the retransmit timer, we want 1/2 tick of rounding and
2907 * 1 extra tick because of +-1/2 tick uncertainty in the
2908 * firing of the timer. The bias will give us exactly the
2909 * 1.5 tick we need. But, because the bias is
2910 * statistical, we have to test that we don't drop below
2911 * the minimum feasible timer (which is 2 ticks).
2912 */
2913 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp),
2914 max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX);
2915
073ec6c4
SZ
2916 if (rebaserto) {
2917 if (tp->t_rxtcur < tp->t_rxtcur_prev + tcp_eifel_rtoinc) {
2918 /*
2919 * RFC4015 requires that the new RTO is at least
2920 * 2*G (tcp_eifel_rtoinc) greater then the RTO
2921 * (t_rxtcur_prev) when the spurious retransmit
2922 * timeout happens.
2923 *
2924 * The above condition could be true, if the SRTT
2925 * and RTTVAR used to calculate t_rxtcur_prev
2926 * resulted in a value less than t_rttmin. So
2927 * simply increasing SRTT by tcp_eifel_rtoinc when
e1dd9e15 2928 * preparing for the Eifel response could not ensure
073ec6c4
SZ
2929 * that the new RTO will be tcp_eifel_rtoinc greater
2930 * t_rxtcur_prev.
2931 */
2932 tp->t_rxtcur = tp->t_rxtcur_prev + tcp_eifel_rtoinc;
2933 }
2934#ifdef DEBUG_EIFEL_RESPONSE
2935 kprintf("new %d\n", tp->t_rxtcur);
2936#endif
2937 }
2938
984263bc
MD
2939 /*
2940 * We received an ack for a packet that wasn't retransmitted;
2941 * it is probably safe to discard any error indications we've
2942 * received recently. This isn't quite right, but close enough
2943 * for now (a route might have failed after we sent a segment,
2944 * and the return path might not be symmetrical).
2945 */
2946 tp->t_softerror = 0;
2947}
2948
2949/*
2950 * Determine a reasonable value for maxseg size.
2951 * If the route is known, check route for mtu.
2952 * If none, use an mss that can be handled on the outgoing
2953 * interface without forcing IP to fragment; if bigger than
2954 * an mbuf cluster (MCLBYTES), round down to nearest multiple of MCLBYTES
2955 * to utilize large mbufs. If no route is found, route has no mtu,
2956 * or the destination isn't local, use a default, hopefully conservative
2957 * size (usually 512 or the default IP max size, but no more than the mtu
2958 * of the interface), as we can't discover anything about intervening
2959 * gateways or networks. We also initialize the congestion/slow start
2960 * window to be a single segment if the destination isn't local.
2961 * While looking at the routing entry, we also initialize other path-dependent
2962 * parameters from pre-set or cached values in the routing entry.
2963 *
2964 * Also take into account the space needed for options that we
2965 * send regularly. Make maxseg shorter by that amount to assure
2966 * that we can send maxseg amount of data even when the options
2967 * are present. Store the upper limit of the length of options plus
2968 * data in maxopd.
2969 *
2970 * NOTE that this routine is only called when we process an incoming
2971 * segment, for outgoing segments only tcp_mssopt is called.
984263bc
MD
2972 */
2973void
95b22adf 2974tcp_mss(struct tcpcb *tp, int offer)
984263bc 2975{
2256ba69 2976 struct rtentry *rt;
984263bc 2977 struct ifnet *ifp;
2256ba69 2978 int rtt, mss;
984263bc
MD
2979 u_long bufsize;
2980 struct inpcb *inp = tp->t_inpcb;
2981 struct socket *so;
984263bc 2982#ifdef INET6
d24ce1dc 2983 boolean_t isipv6 = ((inp->inp_vflag & INP_IPV6) ? TRUE : FALSE);
984263bc
MD
2984 size_t min_protoh = isipv6 ?
2985 sizeof(struct ip6_hdr) + sizeof(struct tcphdr) :
2986 sizeof(struct tcpiphdr);
2987#else
d24ce1dc 2988 const boolean_t isipv6 = FALSE;
984263bc
MD
2989 const size_t min_protoh = sizeof(struct tcpiphdr);
2990#endif
2991
2992 if (isipv6)
2993 rt = tcp_rtlookup6(&inp->inp_inc);
2994 else
2995 rt = tcp_rtlookup(&inp->inp_inc);
2996 if (rt == NULL) {
2997 tp->t_maxopd = tp->t_maxseg =
d24ce1dc 2998 (isipv6 ? tcp_v6mssdflt : tcp_mssdflt);
984263bc
MD
2999 return;
3000 }
3001 ifp = rt->rt_ifp;
3002 so = inp->inp_socket;
3003
984263bc
MD
3004 /*
3005 * Offer == 0 means that there was no MSS on the SYN segment,
b235ad6d
MD
3006 * in this case we use either the interface mtu or tcp_mssdflt.
3007 *
3008 * An offer which is too large will be cut down later.
984263bc 3009 */
5b0b9fa5 3010 if (offer == 0) {
b235ad6d
MD
3011 if (isipv6) {
3012 if (in6_localaddr(&inp->in6p_faddr)) {
3013 offer = ND_IFINFO(rt->rt_ifp)->linkmtu -
3014 min_protoh;
3015 } else {
3016 offer = tcp_v6mssdflt;
3017 }
3018 } else {
3019 if (in_localaddr(inp->inp_faddr))
3020 offer = ifp->if_mtu - min_protoh;
3021 else
3022 offer = tcp_mssdflt;
3023 }
5b0b9fa5 3024 }
b235ad6d
MD
3025
3026 /*
3027 * Prevent DoS attack with too small MSS. Round up
3028 * to at least minmss.
3029 *
3030 * Sanity check: make sure that maxopd will be large
3031 * enough to allow some data on segments even is the
3032 * all the option space is used (40bytes). Otherwise
3033 * funny things may happen in tcp_output.
3034 */
3035 offer = max(offer, tcp_minmss);
3036 offer = max(offer, 64);
3037
27b8aee3 3038 rt->rt_rmx.rmx_mssopt = offer;
984263bc
MD
3039
3040 /*
3041 * While we're here, check if there's an initial rtt
3042 * or rttvar. Convert from the route-table units
3043 * to scaled multiples of the slow timeout timer.
3044 */
3045 if (tp->t_srtt == 0 && (rtt = rt->rt_rmx.rmx_rtt)) {
3046 /*
3047 * XXX the lock bit for RTT indicates that the value
3048 * is also a minimum value; this is subject to time.
3049 */
3050 if (rt->rt_rmx.rmx_locks & RTV_RTT)
3051 tp->t_rttmin = rtt / (RTM_RTTUNIT / hz);
3052 tp->t_srtt = rtt / (RTM_RTTUNIT / (hz * TCP_RTT_SCALE));
3053 tp->t_rttbest = tp->t_srtt + TCP_RTT_SCALE;
3054 tcpstat.tcps_usedrtt++;
3055 if (rt->rt_rmx.rmx_rttvar) {
3056 tp->t_rttvar = rt->rt_rmx.rmx_rttvar /
3057 (RTM_RTTUNIT / (hz * TCP_RTTVAR_SCALE));
3058 tcpstat.tcps_usedrttvar++;
3059 } else {
3060 /* default variation is +- 1 rtt */
3061 tp->t_rttvar =
3062 tp->t_srtt * TCP_RTTVAR_SCALE / TCP_RTT_SCALE;
3063 }
3064 TCPT_RANGESET(tp->t_rxtcur,
3065 ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1,
3066 tp->t_rttmin, TCPTV_REXMTMAX);
3067 }
b235ad6d 3068
984263bc
MD
3069 /*
3070 * if there's an mtu associated with the route, use it
b235ad6d
MD
3071 * else, use the link mtu. Take the smaller of mss or offer
3072 * as our final mss.
984263bc 3073 */
b235ad6d 3074 if (rt->rt_rmx.rmx_mtu) {
984263bc 3075 mss = rt->rt_rmx.rmx_mtu - min_protoh;
b235ad6d
MD
3076 } else {
3077 if (isipv6)
698ac46c 3078 mss = ND_IFINFO(rt->rt_ifp)->linkmtu - min_protoh;
b235ad6d 3079 else
984263bc 3080 mss = ifp->if_mtu - min_protoh;
984263bc
MD
3081 }
3082 mss = min(mss, offer);
b235ad6d 3083
984263bc
MD
3084 /*
3085 * maxopd stores the maximum length of data AND options
3086 * in a segment; maxseg is the amount of data in a normal
3087 * segment. We need to store this value (maxopd) apart
3088 * from maxseg, because now every segment carries options
3089 * and thus we normally have somewhat less data in segments.
3090 */
3091 tp->t_maxopd = mss;
3092
61896e3c 3093 if ((tp->t_flags & (TF_REQ_TSTMP | TF_NOOPT)) == TF_REQ_TSTMP &&
27b8aee3 3094 ((tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP))
984263bc 3095 mss -= TCPOLEN_TSTAMP_APPA;
984263bc
MD
3096
3097#if (MCLBYTES & (MCLBYTES - 1)) == 0
f99dae5e
SW
3098 if (mss > MCLBYTES)
3099 mss &= ~(MCLBYTES-1);
984263bc 3100#else
f99dae5e
SW
3101 if (mss > MCLBYTES)
3102 mss = mss / MCLBYTES * MCLBYTES;
984263bc
MD
3103#endif
3104 /*
3105 * If there's a pipesize, change the socket buffer
3106 * to that size. Make the socket buffers an integral
3107 * number of mss units; if the mss is larger than
3108 * the socket buffer, decrease the mss.
3109 */
3110#ifdef RTV_SPIPE
3111 if ((bufsize = rt->rt_rmx.rmx_sendpipe) == 0)
3112#endif
6d49aa6f 3113 bufsize = so->so_snd.ssb_hiwat;
984263bc
MD
3114 if (bufsize < mss)
3115 mss = bufsize;
3116 else {
3117 bufsize = roundup(bufsize, mss);
3118 if (bufsize > sb_max)
3119 bufsize = sb_max;
6d49aa6f
MD
3120 if (bufsize > so->so_snd.ssb_hiwat)
3121 ssb_reserve(&so->so_snd, bufsize, so, NULL);
984263bc
MD
3122 }
3123 tp->t_maxseg = mss;
3124
3125#ifdef RTV_RPIPE
3126 if ((bufsize = rt->rt_rmx.rmx_recvpipe) == 0)
3127#endif
6d49aa6f 3128 bufsize = so->so_rcv.ssb_hiwat;
984263bc
MD
3129 if (bufsize > mss) {
3130 bufsize = roundup(bufsize, mss);
3131 if (bufsize > sb_max)
3132 bufsize = sb_max;
6cef7136
MD
3133 if (bufsize > so->so_rcv.ssb_hiwat) {
3134 lwkt_gettoken(&so->so_rcv.ssb_token);
6d49aa6f 3135 ssb_reserve(&so->so_rcv, bufsize, so, NULL);
6cef7136
MD
3136 lwkt_reltoken(&so->so_rcv.ssb_token);
3137 }
984263bc
MD
3138 }
3139
3140 /*
697020f5
SZ
3141 * Set the slow-start flight size
3142 *
3143 * NOTE: t_maxseg must have been configured!
984263bc 3144 */
697020f5 3145 tp->snd_cwnd = tcp_initial_window(tp);
984263bc
MD
3146
3147 if (rt->rt_rmx.rmx_ssthresh) {
3148 /*
3149 * There's some sort of gateway or interface
3150 * buffer limit on the path. Use this to set
3151 * the slow start threshhold, but set the
3152 * threshold to no less than 2*mss.
3153 */
3154 tp->snd_ssthresh = max(2 * mss, rt->rt_rmx.rmx_ssthresh);
3155 tcpstat.tcps_usedssthresh++;
3156 }
3157}
3158
3159/*
3160 * Determine the MSS option to send on an outgoing SYN.
3161 */
3162int
95b22adf 3163tcp_mssopt(struct tcpcb *tp)
984263bc
MD
3164{
3165 struct rtentry *rt;
3166#ifdef INET6
d24ce1dc
JH
3167 boolean_t isipv6 =
3168 ((tp->t_inpcb->inp_vflag & INP_IPV6) ? TRUE : FALSE);
984263bc
MD
3169 int min_protoh = isipv6 ?
3170 sizeof(struct ip6_hdr) + sizeof(struct tcphdr) :
3171 sizeof(struct tcpiphdr);
3172#else
d24ce1dc 3173 const boolean_t isipv6 = FALSE;
984263bc
MD
3174 const size_t min_protoh = sizeof(struct tcpiphdr);
3175#endif
3176
3177 if (isipv6)
3178 rt = tcp_rtlookup6(&tp->t_inpcb->inp_inc);
3179 else
3180 rt = tcp_rtlookup(&tp->t_inpcb->inp_inc);
3181 if (rt == NULL)
3182 return (isipv6 ? tcp_v6mssdflt : tcp_mssdflt);
3183
3184 return (rt->rt_ifp->if_mtu - min_protoh);
3185}
3186
984263bc
MD
3187/*
3188 * When a partial ack arrives, force the retransmission of the
91489f6b
JH
3189 * next unacknowledged segment. Do not exit Fast Recovery.
3190 *
3191 * Implement the Slow-but-Steady variant of NewReno by restarting the
3192 * the retransmission timer. Turn it off here so it can be restarted
3193 * later in tcp_output().
984263bc
MD
3194 */
3195static void
91489f6b 3196tcp_newreno_partial_ack(struct tcpcb *tp, struct tcphdr *th, int acked)
984263bc 3197{
91489f6b
JH
3198 tcp_seq old_snd_nxt = tp->snd_nxt;
3199 u_long ocwnd = tp->snd_cwnd;
984263bc 3200
a48c5dd5 3201 tcp_callout_stop(tp, tp->tt_rexmt);
984263bc
MD
3202 tp->t_rtttime = 0;
3203 tp->snd_nxt = th->th_ack;
91489f6b
JH
3204 /* Set snd_cwnd to one segment beyond acknowledged offset. */
3205 tp->snd_cwnd = tp->t_maxseg;
984263bc 3206 tp->t_flags |= TF_ACKNOW;
f23061d4 3207 tcp_output(tp);
91489f6b
JH
3208 if (SEQ_GT(old_snd_nxt, tp->snd_nxt))
3209 tp->snd_nxt = old_snd_nxt;
3210 /* partial window deflation */
68947d12
ND
3211 if (ocwnd > acked)
3212 tp->snd_cwnd = ocwnd - acked + tp->t_maxseg;
3213 else
3214 tp->snd_cwnd = tp->t_maxseg;
91489f6b
JH
3215}
3216
3217/*
3218 * In contrast to the Slow-but-Steady NewReno variant,
3219 * we do not reset the retransmission timer for SACK retransmissions,
3220 * except when retransmitting snd_una.
3221 */
3222static void
ccb518ea 3223tcp_sack_rexmt(struct tcpcb *tp, boolean_t force)
91489f6b 3224{
91489f6b
JH
3225 tcp_seq old_snd_nxt = tp->snd_nxt;
3226 u_long ocwnd = tp->snd_cwnd;
1bdfd728 3227 uint32_t pipe;
91489f6b 3228 int nseg = 0; /* consecutive new segments */
a098966f 3229 int nseg_rexmt = 0; /* retransmitted segments */
ccb518ea 3230 int maxrexmt = 0;
91489f6b
JH
3231#define MAXBURST 4 /* limit burst of new packets on partial ack */
3232
ccb518ea
SZ
3233 if (force) {
3234 uint32_t unsacked = tcp_sack_first_unsacked_len(tp);
3235
3236 /*
3237 * Try to fill the first hole in the receiver's
3238 * reassemble queue.
3239 */
3240 maxrexmt = howmany(unsacked, tp->t_maxseg);
3241 if (maxrexmt > tcp_force_sackrxt)
3242 maxrexmt = tcp_force_sackrxt;
3243 }
3244
91489f6b
JH
3245 tp->t_rtttime = 0;
3246 pipe = tcp_sack_compute_pipe(tp);
ccb518ea
SZ
3247 while (((tcp_seq_diff_t)(ocwnd - pipe) >= (tcp_seq_diff_t)tp->t_maxseg
3248 || (force && nseg_rexmt < maxrexmt && nseg == 0)) &&
1bdfd728
SZ
3249 (!tcp_do_smartsack || nseg < MAXBURST)) {
3250 tcp_seq old_snd_max, old_rexmt_high, nextrexmt;
3251 uint32_t sent, seglen;
3252 boolean_t rescue;
91489f6b
JH
3253 int error;
3254
1bdfd728 3255 old_rexmt_high = tp->rexmt_high;
64debfd6 3256 if (!tcp_sack_nextseg(tp, &nextrexmt, &seglen, &rescue)) {
1bdfd728
SZ
3257 tp->rexmt_high = old_rexmt_high;
3258 break;
3259 }
3260
a098966f
SZ
3261 /*
3262 * If the next tranmission is a rescue retranmission,
3263 * we check whether we have already sent some data
3264 * (either new segments or retransmitted segments)
3265 * into the the network or not. Since the idea of rescue
3266 * retransmission is to sustain ACK clock, as long as
3267 * some segments are in the network, ACK clock will be
3268 * kept ticking.
3269 */
3270 if (rescue && (nseg_rexmt > 0 || nseg > 0)) {
3271 tp->rexmt_high = old_rexmt_high;
3272 break;
3273 }
3274
98cb2337
MD
3275 if (nextrexmt == tp->snd_max)
3276 ++nseg;
a098966f
SZ
3277 else
3278 ++nseg_rexmt;
91489f6b
JH
3279 tp->snd_nxt = nextrexmt;
3280 tp->snd_cwnd = nextrexmt - tp->snd_una + seglen;
3281 old_snd_max = tp->snd_max;
3282 if (nextrexmt == tp->snd_una)
a48c5dd5 3283 tcp_callout_stop(tp, tp->tt_rexmt);
c1fabe85 3284 tp->t_flags |= TF_XMITNOW;
91489f6b 3285 error = tcp_output(tp);
1bdfd728
SZ
3286 if (error != 0) {
3287 tp->rexmt_high = old_rexmt_high;
91489f6b 3288 break;
1bdfd728 3289 }
91489f6b 3290 sent = tp->snd_nxt - nextrexmt;
1bdfd728
SZ
3291 if (sent <= 0) {
3292 tp->rexmt_high = old_rexmt_high;
91489f6b 3293 break;
1bdfd728
SZ
3294 }
3295 pipe += sent;
91489f6b
JH
3296 tcpstat.tcps_sndsackpack++;
3297 tcpstat.tcps_sndsackbyte += sent;
1bdfd728
SZ
3298
3299 if (rescue) {
a098966f 3300 tcpstat.tcps_sackrescue++;
1bdfd728 3301 tp->rexmt_rescue = tp->snd_nxt;
c7e6499a 3302 tp->sack_flags |= TSACK_F_SACKRESCUED;
1bdfd728
SZ
3303 break;
3304 }
91489f6b 3305 if (SEQ_LT(nextrexmt, old_snd_max) &&
a098966f 3306 SEQ_LT(tp->rexmt_high, tp->snd_nxt)) {
91489f6b 3307 tp->rexmt_high = seq_min(tp->snd_nxt, old_snd_max);
21f337ca 3308 if (tcp_aggressive_rescuesack &&
c7e6499a 3309 (tp->sack_flags & TSACK_F_SACKRESCUED) &&
a098966f
SZ
3310 SEQ_LT(tp->rexmt_rescue, tp->rexmt_high)) {
3311 /* Drag RescueRxt along with HighRxt */
3312 tp->rexmt_rescue = tp->rexmt_high;
3313 }
3314 }
91489f6b
JH
3315 }
3316 if (SEQ_GT(old_snd_nxt, tp->snd_nxt))
3317 tp->snd_nxt = old_snd_nxt;
984263bc 3318 tp->snd_cwnd = ocwnd;
984263bc 3319}
0ecd93f9 3320
e2289e66
SZ
3321/*
3322 * Return TRUE, if some new segments are sent
3323 */
ffe35e17
SZ
3324static boolean_t
3325tcp_sack_limitedxmit(struct tcpcb *tp)
3326{
3327 tcp_seq oldsndnxt = tp->snd_nxt;
3328 tcp_seq oldsndmax = tp->snd_max;
3329 u_long ocwnd = tp->snd_cwnd;
db421eef 3330 uint32_t pipe, sent;
ffe35e17 3331 boolean_t ret = FALSE;
db421eef
SZ
3332 tcp_seq_diff_t cwnd_left;
3333 tcp_seq next;
ffe35e17
SZ
3334
3335 tp->rexmt_high = tp->snd_una - 1;
3336 pipe = tcp_sack_compute_pipe(tp);
db421eef
SZ
3337 cwnd_left = (tcp_seq_diff_t)(ocwnd - pipe);
3338 if (cwnd_left < (tcp_seq_diff_t)tp->t_maxseg)
3339 return FALSE;
ffe35e17 3340
db421eef
SZ
3341 next = tp->snd_nxt = tp->snd_max;
3342 tp->snd_cwnd = tp->snd_nxt - tp->snd_una +
3343 rounddown(cwnd_left, tp->t_maxseg);
ffe35e17 3344
c1fabe85 3345 tp->t_flags |= TF_XMITNOW;
db421eef 3346 tcp_output(tp);
ffe35e17 3347
db421eef
SZ
3348 sent = tp->snd_nxt - next;
3349 if (sent > 0) {
3350 tcpstat.tcps_sndlimited += howmany(sent, tp->t_maxseg);
ffe35e17
SZ
3351 ret = TRUE;
3352 }
3353
3354 if (SEQ_LT(oldsndnxt, oldsndmax)) {
3355 KASSERT(SEQ_GEQ(oldsndnxt, tp->snd_una),
3356 ("snd_una moved in other threads"));
3357 tp->snd_nxt = oldsndnxt;
3358 }
3359 tp->snd_cwnd = ocwnd;
3360
e2289e66
SZ
3361 if (ret && TCP_DO_NCR(tp))
3362 tcp_ncr_update_rxtthresh(tp);
3363
ffe35e17
SZ
3364 return ret;
3365}
3366
0ecd93f9
MD
3367/*
3368 * Reset idle time and keep-alive timer, typically called when a valid
3369 * tcp packet is received but may also be called when FASTKEEP is set
3370 * to prevent the previous long-timeout from calculating to a drop.
3371 *
3372 * Only update t_rcvtime for non-SYN packets.
3373 *
3374 * Handle the case where one side thinks the connection is established
3375 * but the other side has, say, rebooted without cleaning out the
3376 * connection. The SYNs could be construed as an attack and wind
3377 * up ignored, but in case it isn't an attack we can validate the
3378 * connection by forcing a keepalive.
3379 */
3380void
3381tcp_timer_keep_activity(struct tcpcb *tp, int thflags)
3382{
3383 if (TCPS_HAVEESTABLISHED(tp->t_state)) {
3384 if ((thflags & (TH_SYN | TH_ACK)) == TH_SYN) {
3385 tp->t_flags |= TF_KEEPALIVE;
3386 tcp_callout_reset(tp, tp->tt_keep, hz / 2,
3387 tcp_timer_keep);
3388 } else {
3389 tp->t_rcvtime = ticks;
3390 tp->t_flags &= ~TF_KEEPALIVE;
3391 tcp_callout_reset(tp, tp->tt_keep,
fb8d5c6d 3392 tp->t_keepidle,
0ecd93f9
MD
3393 tcp_timer_keep);
3394 }
3395 }
3396}
01d3427a
SZ
3397
3398static int
3399tcp_rmx_msl(const struct tcpcb *tp)
3400{
3401 struct rtentry *rt;
3402 struct inpcb *inp = tp->t_inpcb;
9855a4ef 3403 int msl;
01d3427a
SZ
3404#ifdef INET6
3405 boolean_t isipv6 = ((inp->inp_vflag & INP_IPV6) ? TRUE : FALSE);
3406#else
3407 const boolean_t isipv6 = FALSE;
3408#endif
3409
3410 if (isipv6)
3411 rt = tcp_rtlookup6(&inp->inp_inc);
3412 else
3413 rt = tcp_rtlookup(&inp->inp_inc);
3414 if (rt == NULL || rt->rt_rmx.rmx_msl == 0)
3415 return tcp_msl;
3416
9855a4ef
SZ
3417 msl = (rt->rt_rmx.rmx_msl * hz) / 1000;
3418 if (msl == 0)
3419 msl = 1;
3420
3421 return msl;
01d3427a 3422}
8651f7f8
SZ
3423
3424static void
3425tcp_established(struct tcpcb *tp)
3426{
3427 tp->t_state = TCPS_ESTABLISHED;
fb8d5c6d 3428 tcp_callout_reset(tp, tp->tt_keep, tp->t_keepidle, tcp_timer_keep);
be34e534 3429
d5082e3d 3430 if (tp->t_rxtsyn > 0) {
48a4676d
SZ
3431 /*
3432 * RFC6298:
3433 * "If the timer expires awaiting the ACK of a SYN segment
3434 * and the TCP implementation is using an RTO less than 3
3435 * seconds, the RTO MUST be re-initialized to 3 seconds
3436 * when data transmission begins"
3437 */
3438 if (tp->t_rxtcur < TCPTV_RTOBASE3)
3439 tp->t_rxtcur = TCPTV_RTOBASE3;
be34e534 3440 }
8651f7f8 3441}
27f4bf33
SZ
3442
3443/*
3444 * Returns TRUE, if the ACK should be dropped
3445 */
3446static boolean_t
0a832381 3447tcp_recv_dupack(struct tcpcb *tp, tcp_seq th_ack, u_int to_flags)
27f4bf33 3448{
ba0d6f99
SZ
3449 boolean_t fast_sack_rexmt = TRUE;
3450
27f4bf33
SZ
3451 tcpstat.tcps_rcvdupack++;
3452
3453 /*
3454 * We have outstanding data (other than a window probe),
3455 * this is a completely duplicate ack (ie, window info
3456 * didn't change), the ack is the biggest we've seen and
3457 * we've seen exactly our rexmt threshhold of them, so
3458 * assume a packet has been dropped and retransmit it.
3459 * Kludge snd_nxt & the congestion window so we send only
3460 * this one packet.
3461 */
<