tcp: Limit new segements burst to 4 during extended limited transmit
[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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137/*
138 * Limit burst of new packets during SACK based fast recovery
139 * or extended limited transmit.
140 */
141#define TCP_SACK_MAXBURST 4
142
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143MALLOC_DEFINE(M_TSEGQ, "tseg_qent", "TCP segment queue entry");
144
984263bc 145static int log_in_vain = 0;
d24ce1dc 146SYSCTL_INT(_net_inet_tcp, OID_AUTO, log_in_vain, CTLFLAG_RW,
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147 &log_in_vain, 0, "Log all incoming TCP connections");
148
149static int blackhole = 0;
150SYSCTL_INT(_net_inet_tcp, OID_AUTO, blackhole, CTLFLAG_RW,
151 &blackhole, 0, "Do not send RST when dropping refused connections");
152
153int tcp_delack_enabled = 1;
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154SYSCTL_INT(_net_inet_tcp, OID_AUTO, delayed_ack, CTLFLAG_RW,
155 &tcp_delack_enabled, 0,
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156 "Delay ACK to try and piggyback it onto a data packet");
157
158#ifdef TCP_DROP_SYNFIN
159static int drop_synfin = 0;
160SYSCTL_INT(_net_inet_tcp, OID_AUTO, drop_synfin, CTLFLAG_RW,
161 &drop_synfin, 0, "Drop TCP packets with SYN+FIN set");
162#endif
163
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164static int tcp_do_limitedtransmit = 1;
165SYSCTL_INT(_net_inet_tcp, OID_AUTO, limitedtransmit, CTLFLAG_RW,
166 &tcp_do_limitedtransmit, 0, "Enable RFC 3042 (Limited Transmit)");
167
91489f6b 168static int tcp_do_early_retransmit = 1;
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169SYSCTL_INT(_net_inet_tcp, OID_AUTO, earlyretransmit, CTLFLAG_RW,
170 &tcp_do_early_retransmit, 0, "Early retransmit");
171
8acdb67c 172int tcp_aggregate_acks = 1;
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173SYSCTL_INT(_net_inet_tcp, OID_AUTO, aggregate_acks, CTLFLAG_RW,
174 &tcp_aggregate_acks, 0, "Aggregate built-up acks into one ack");
175
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176static int tcp_do_eifel_detect = 1;
177SYSCTL_INT(_net_inet_tcp, OID_AUTO, eifel, CTLFLAG_RW,
178 &tcp_do_eifel_detect, 0, "Eifel detection algorithm (RFC 3522)");
179
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180static int tcp_do_abc = 1;
181SYSCTL_INT(_net_inet_tcp, OID_AUTO, abc, CTLFLAG_RW,
182 &tcp_do_abc, 0,
183 "TCP Appropriate Byte Counting (RFC 3465)");
184
91489f6b 185/*
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186 * The following value actually takes range [25ms, 250ms],
187 * given that most modern systems use 1ms ~ 10ms as the unit
188 * of timestamp option.
189 */
190static u_int tcp_paws_tolerance = 25;
191SYSCTL_UINT(_net_inet_tcp, OID_AUTO, paws_tolerance, CTLFLAG_RW,
192 &tcp_paws_tolerance, 0, "RFC1323 PAWS tolerance");
193
194/*
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195 * Define as tunable for easy testing with SACK on and off.
196 * Warning: do not change setting in the middle of an existing active TCP flow,
197 * else strange things might happen to that flow.
198 */
6e5bbdda 199int tcp_do_sack = 1;
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200SYSCTL_INT(_net_inet_tcp, OID_AUTO, sack, CTLFLAG_RW,
201 &tcp_do_sack, 0, "Enable SACK Algorithms");
202
203int tcp_do_smartsack = 1;
204SYSCTL_INT(_net_inet_tcp, OID_AUTO, smartsack, CTLFLAG_RW,
205 &tcp_do_smartsack, 0, "Enable Smart SACK Algorithms");
206
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207int tcp_do_rescuesack = 1;
208SYSCTL_INT(_net_inet_tcp, OID_AUTO, rescuesack, CTLFLAG_RW,
209 &tcp_do_rescuesack, 0, "Rescue retransmission for SACK");
210
c01f968f 211int tcp_aggressive_rescuesack = 0;
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212SYSCTL_INT(_net_inet_tcp, OID_AUTO, rescuesack_agg, CTLFLAG_RW,
213 &tcp_aggressive_rescuesack, 0, "Aggressive rescue retransmission for SACK");
214
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215static int tcp_force_sackrxt = 1;
216SYSCTL_INT(_net_inet_tcp, OID_AUTO, force_sackrxt, CTLFLAG_RW,
217 &tcp_force_sackrxt, 0, "Allowed forced SACK retransmit burst");
218
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219int tcp_do_rfc6675 = 1;
220SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc6675, CTLFLAG_RW,
221 &tcp_do_rfc6675, 0, "Enable RFC6675");
ffe35e17 222
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223int tcp_rfc6675_rxt = 0;
224SYSCTL_INT(_net_inet_tcp, OID_AUTO, rfc6675_rxt, CTLFLAG_RW,
225 &tcp_rfc6675_rxt, 0, "Enable RFC6675 retransmit");
5fd89c20 226
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227SYSCTL_NODE(_net_inet_tcp, OID_AUTO, reass, CTLFLAG_RW, 0,
228 "TCP Segment Reassembly Queue");
229
230int tcp_reass_maxseg = 0;
231SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, maxsegments, CTLFLAG_RD,
232 &tcp_reass_maxseg, 0,
233 "Global maximum number of TCP Segments in Reassembly Queue");
234
235int tcp_reass_qsize = 0;
236SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, cursegments, CTLFLAG_RD,
237 &tcp_reass_qsize, 0,
238 "Global number of TCP Segments currently in Reassembly Queue");
239
240static int tcp_reass_overflows = 0;
241SYSCTL_INT(_net_inet_tcp_reass, OID_AUTO, overflows, CTLFLAG_RD,
242 &tcp_reass_overflows, 0,
243 "Global number of TCP Segment Reassembly Queue Overflows");
244
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245int tcp_do_autorcvbuf = 1;
246SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_auto, CTLFLAG_RW,
247 &tcp_do_autorcvbuf, 0, "Enable automatic receive buffer sizing");
248
249int tcp_autorcvbuf_inc = 16*1024;
250SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_inc, CTLFLAG_RW,
251 &tcp_autorcvbuf_inc, 0,
252 "Incrementor step size of automatic receive buffer");
253
46e92930 254int tcp_autorcvbuf_max = 2*1024*1024;
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255SYSCTL_INT(_net_inet_tcp, OID_AUTO, recvbuf_max, CTLFLAG_RW,
256 &tcp_autorcvbuf_max, 0, "Max size of automatic receive buffer");
257
b3f79714 258int tcp_sosend_agglim = 3;
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259SYSCTL_INT(_net_inet_tcp, OID_AUTO, sosend_agglim, CTLFLAG_RW,
260 &tcp_sosend_agglim, 0, "TCP sosend mbuf aggregation limit");
5b0b9fa5 261
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262int tcp_sosend_async = 1;
263SYSCTL_INT(_net_inet_tcp, OID_AUTO, sosend_async, CTLFLAG_RW,
264 &tcp_sosend_async, 0, "TCP asynchronized pru_send");
f2a3782e 265
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266static int tcp_ignore_redun_dsack = 1;
267SYSCTL_INT(_net_inet_tcp, OID_AUTO, ignore_redun_dsack, CTLFLAG_RW,
268 &tcp_ignore_redun_dsack, 0, "Ignore redundant DSACK");
269
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270static void tcp_dooptions(struct tcpopt *, u_char *, int, boolean_t,
271 tcp_seq);
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272static void tcp_pulloutofband(struct socket *,
273 struct tcphdr *, struct mbuf *, int);
274static int tcp_reass(struct tcpcb *, struct tcphdr *, int *,
275 struct mbuf *);
073ec6c4 276static void tcp_xmit_timer(struct tcpcb *, int, tcp_seq);
91489f6b 277static void tcp_newreno_partial_ack(struct tcpcb *, struct tcphdr *, int);
ccb518ea 278static void tcp_sack_rexmt(struct tcpcb *, boolean_t);
ffe35e17 279static boolean_t tcp_sack_limitedxmit(struct tcpcb *);
01d3427a 280static int tcp_rmx_msl(const struct tcpcb *);
8651f7f8 281static void tcp_established(struct tcpcb *);
0a832381 282static boolean_t tcp_recv_dupack(struct tcpcb *, tcp_seq, u_int);
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283
284/* Neighbor Discovery, Neighbor Unreachability Detection Upper layer hint. */
285#ifdef INET6
286#define ND6_HINT(tp) \
287do { \
288 if ((tp) && (tp)->t_inpcb && \
61896e3c 289 ((tp)->t_inpcb->inp_vflag & INP_IPV6) && \
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290 (tp)->t_inpcb->in6p_route.ro_rt) \
291 nd6_nud_hint((tp)->t_inpcb->in6p_route.ro_rt, NULL, 0); \
292} while (0)
293#else
294#define ND6_HINT(tp)
295#endif
296
297/*
298 * Indicate whether this ack should be delayed. We can delay the ack if
299 * - delayed acks are enabled and
300 * - there is no delayed ack timer in progress and
301 * - our last ack wasn't a 0-sized window. We never want to delay
302 * the ack that opens up a 0-sized window.
303 */
304#define DELAY_ACK(tp) \
a48c5dd5 305 (tcp_delack_enabled && !tcp_callout_pending(tp, tp->tt_delack) && \
61896e3c 306 !(tp->t_flags & TF_RXWIN0SENT))
984263bc 307
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308#define acceptable_window_update(tp, th, tiwin) \
309 (SEQ_LT(tp->snd_wl1, th->th_seq) || \
310 (tp->snd_wl1 == th->th_seq && \
311 (SEQ_LT(tp->snd_wl2, th->th_ack) || \
312 (tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))))
313
ffe35e17
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314#define iceildiv(n, d) (((n)+(d)-1) / (d))
315#define need_early_retransmit(tp, ownd) \
316 (tcp_do_early_retransmit && \
317 (tcp_do_eifel_detect && (tp->t_flags & TF_RCVD_TSTMP)) && \
4c0f4a00 318 ownd < ((tp->t_rxtthresh + 1) * tp->t_maxseg) && \
ffe35e17
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319 tp->t_dupacks + 1 >= iceildiv(ownd, tp->t_maxseg) && \
320 (!TCP_DO_SACK(tp) || ownd <= tp->t_maxseg || \
321 tcp_sack_has_sacked(&tp->scb, ownd - tp->t_maxseg)))
322
9de1f696
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323/*
324 * Returns TRUE, if this segment can be merged with the last
325 * pending segment in the reassemble queue and this segment
326 * does not overlap with the pending segment immediately
327 * preceeding the last pending segment.
328 */
329static __inline boolean_t
330tcp_paws_canreasslast(const struct tcpcb *tp, const struct tcphdr *th, int tlen)
331{
332 const struct tseg_qent *last, *prev;
333
334 last = TAILQ_LAST(&tp->t_segq, tsegqe_head);
335 if (last == NULL)
336 return FALSE;
337
338 /* This segment comes immediately after the last pending segment */
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339 if (last->tqe_th->th_seq + last->tqe_len == th->th_seq) {
340 if (last->tqe_th->th_flags & TH_FIN) {
341 /* No segments should follow segment w/ FIN */
342 return FALSE;
343 }
9de1f696 344 return TRUE;
04e6f08e 345 }
9de1f696
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346
347 if (th->th_seq + tlen != last->tqe_th->th_seq)
348 return FALSE;
349 /* This segment comes immediately before the last pending segment */
350
351 prev = TAILQ_PREV(last, tsegqe_head, tqe_q);
352 if (prev == NULL) {
353 /*
354 * No pending preceeding segment, we assume this segment
355 * could be reassembled.
356 */
357 return TRUE;
358 }
359
360 /* This segment does not overlap with the preceeding segment */
361 if (SEQ_GEQ(th->th_seq, prev->tqe_th->th_seq + prev->tqe_len))
362 return TRUE;
363
364 return FALSE;
365}
366
e2289e66
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367static __inline void
368tcp_ncr_update_rxtthresh(struct tcpcb *tp)
369{
370 int old_rxtthresh = tp->t_rxtthresh;
371 uint32_t ownd = tp->snd_max - tp->snd_una;
372
0983a903 373 tp->t_rxtthresh = max(tcprexmtthresh, ((ownd / tp->t_maxseg) >> 1));
e2289e66
SZ
374 if (tp->t_rxtthresh != old_rxtthresh) {
375 tcp_sack_update_lostseq(&tp->scb, tp->snd_una,
376 tp->t_maxseg, tp->t_rxtthresh);
377 }
378}
379
984263bc 380static int
95b22adf 381tcp_reass(struct tcpcb *tp, struct tcphdr *th, int *tlenp, struct mbuf *m)
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MD
382{
383 struct tseg_qent *q;
384 struct tseg_qent *p = NULL;
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MD
385 struct tseg_qent *te;
386 struct socket *so = tp->t_inpcb->inp_socket;
387 int flags;
388
389 /*
61896e3c 390 * Call with th == NULL after become established to
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MD
391 * force pre-ESTABLISHED data up to user socket.
392 */
61896e3c 393 if (th == NULL)
984263bc
MD
394 goto present;
395
3edf7c37
RG
396 /*
397 * Limit the number of segments in the reassembly queue to prevent
398 * holding on to too many segments (and thus running out of mbufs).
399 * Make sure to let the missing segment through which caused this
400 * queue. Always keep one global queue entry spare to be able to
401 * process the missing segment.
402 */
403 if (th->th_seq != tp->rcv_nxt &&
404 tcp_reass_qsize + 1 >= tcp_reass_maxseg) {
405 tcp_reass_overflows++;
406 tcpstat.tcps_rcvmemdrop++;
407 m_freem(m);
91489f6b
JH
408 /* no SACK block to report */
409 tp->reportblk.rblk_start = tp->reportblk.rblk_end;
3edf7c37
RG
410 return (0);
411 }
412
ba4e3dbe 413 /* Allocate a new queue entry. */
884717e1 414 te = kmalloc(sizeof(struct tseg_qent), M_TSEGQ, M_INTWAIT | M_NULLOK);
984263bc
MD
415 if (te == NULL) {
416 tcpstat.tcps_rcvmemdrop++;
417 m_freem(m);
91489f6b
JH
418 /* no SACK block to report */
419 tp->reportblk.rblk_start = tp->reportblk.rblk_end;
984263bc
MD
420 return (0);
421 }
2d23a8be 422 atomic_add_int(&tcp_reass_qsize, 1);
984263bc 423
942d88ef
SZ
424 if (th->th_flags & TH_FIN)
425 tp->t_flags |= TF_QUEDFIN;
426
984263bc
MD
427 /*
428 * Find a segment which begins after this one does.
429 */
0f9e45de 430 TAILQ_FOREACH(q, &tp->t_segq, tqe_q) {
984263bc
MD
431 if (SEQ_GT(q->tqe_th->th_seq, th->th_seq))
432 break;
433 p = q;
434 }
435
436 /*
437 * If there is a preceding segment, it may provide some of
438 * our data already. If so, drop the data from the incoming
439 * segment. If it provides all of our data, drop us.
440 */
441 if (p != NULL) {
76cf5e41 442 tcp_seq_diff_t i;
91489f6b 443
984263bc
MD
444 /* conversion to int (in i) handles seq wraparound */
445 i = p->tqe_th->th_seq + p->tqe_len - th->th_seq;
91489f6b 446 if (i > 0) { /* overlaps preceding segment */
c7e6499a
SZ
447 tp->sack_flags |=
448 (TSACK_F_DUPSEG | TSACK_F_ENCLOSESEG);
91489f6b
JH
449 /* enclosing block starts w/ preceding segment */
450 tp->encloseblk.rblk_start = p->tqe_th->th_seq;
984263bc 451 if (i >= *tlenp) {
53432bee
SZ
452 if (th->th_flags & TH_FIN)
453 p->tqe_th->th_flags |= TH_FIN;
454
91489f6b 455 /* preceding encloses incoming segment */
3a5d999b
SZ
456 tp->encloseblk.rblk_end = TCP_SACK_BLKEND(
457 p->tqe_th->th_seq + p->tqe_len,
458 p->tqe_th->th_flags);
984263bc
MD
459 tcpstat.tcps_rcvduppack++;
460 tcpstat.tcps_rcvdupbyte += *tlenp;
461 m_freem(m);
efda3bd0 462 kfree(te, M_TSEGQ);
2d23a8be 463 atomic_add_int(&tcp_reass_qsize, -1);
984263bc
MD
464 /*
465 * Try to present any queued data
466 * at the left window edge to the user.
467 * This is needed after the 3-WHS
468 * completes.
469 */
470 goto present; /* ??? */
471 }
472 m_adj(m, i);
473 *tlenp -= i;
474 th->th_seq += i;
91489f6b 475 /* incoming segment end is enclosing block end */
3a5d999b
SZ
476 tp->encloseblk.rblk_end = TCP_SACK_BLKEND(
477 th->th_seq + *tlenp, th->th_flags);
91489f6b
JH
478 /* trim end of reported D-SACK block */
479 tp->reportblk.rblk_end = th->th_seq;
984263bc
MD
480 }
481 }
482 tcpstat.tcps_rcvoopack++;
483 tcpstat.tcps_rcvoobyte += *tlenp;
484
485 /*
486 * While we overlap succeeding segments trim them or,
487 * if they are completely covered, dequeue them.
488 */
489 while (q) {
76cf5e41 490 tcp_seq_diff_t i = (th->th_seq + *tlenp) - q->tqe_th->th_seq;
91489f6b 491 tcp_seq qend = q->tqe_th->th_seq + q->tqe_len;
3a5d999b 492 tcp_seq qend_sack = TCP_SACK_BLKEND(qend, q->tqe_th->th_flags);
91489f6b
JH
493 struct tseg_qent *nq;
494
984263bc
MD
495 if (i <= 0)
496 break;
c7e6499a
SZ
497 if (!(tp->sack_flags & TSACK_F_DUPSEG)) {
498 /* first time through */
499 tp->sack_flags |= (TSACK_F_DUPSEG | TSACK_F_ENCLOSESEG);
91489f6b
JH
500 tp->encloseblk = tp->reportblk;
501 /* report trailing duplicate D-SACK segment */
502 tp->reportblk.rblk_start = q->tqe_th->th_seq;
503 }
c7e6499a 504 if ((tp->sack_flags & TSACK_F_ENCLOSESEG) &&
3a5d999b 505 SEQ_GT(qend_sack, tp->encloseblk.rblk_end)) {
91489f6b 506 /* extend enclosing block if one exists */
3a5d999b 507 tp->encloseblk.rblk_end = qend_sack;
91489f6b 508 }
984263bc
MD
509 if (i < q->tqe_len) {
510 q->tqe_th->th_seq += i;
511 q->tqe_len -= i;
512 m_adj(q->tqe_m, i);
513 break;
514 }
515
53432bee
SZ
516 if (q->tqe_th->th_flags & TH_FIN)
517 th->th_flags |= TH_FIN;
518
0f9e45de
SZ
519 nq = TAILQ_NEXT(q, tqe_q);
520 TAILQ_REMOVE(&tp->t_segq, q, tqe_q);
984263bc 521 m_freem(q->tqe_m);
efda3bd0 522 kfree(q, M_TSEGQ);
2d23a8be 523 atomic_add_int(&tcp_reass_qsize, -1);
984263bc
MD
524 q = nq;
525 }
526
527 /* Insert the new segment queue entry into place. */
528 te->tqe_m = m;
529 te->tqe_th = th;
530 te->tqe_len = *tlenp;
531
91489f6b
JH
532 /* check if can coalesce with following segment */
533 if (q != NULL && (th->th_seq + *tlenp == q->tqe_th->th_seq)) {
53432bee 534 tcp_seq tend_sack;
91489f6b
JH
535
536 te->tqe_len += q->tqe_len;
a174690a 537 if (q->tqe_th->th_flags & TH_FIN)
f16f8cc3 538 te->tqe_th->th_flags |= TH_FIN;
53432bee
SZ
539 tend_sack = TCP_SACK_BLKEND(te->tqe_th->th_seq + te->tqe_len,
540 te->tqe_th->th_flags);
541
91489f6b 542 m_cat(te->tqe_m, q->tqe_m);
3a5d999b 543 tp->encloseblk.rblk_end = tend_sack;
91489f6b
JH
544 /*
545 * When not reporting a duplicate segment, use
546 * the larger enclosing block as the SACK block.
547 */
c7e6499a 548 if (!(tp->sack_flags & TSACK_F_DUPSEG))
3a5d999b 549 tp->reportblk.rblk_end = tend_sack;
0f9e45de 550 TAILQ_REMOVE(&tp->t_segq, q, tqe_q);
efda3bd0 551 kfree(q, M_TSEGQ);
2d23a8be 552 atomic_add_int(&tcp_reass_qsize, -1);
91489f6b
JH
553 }
554
984263bc 555 if (p == NULL) {
0f9e45de 556 TAILQ_INSERT_HEAD(&tp->t_segq, te, tqe_q);
984263bc 557 } else {
91489f6b
JH
558 /* check if can coalesce with preceding segment */
559 if (p->tqe_th->th_seq + p->tqe_len == th->th_seq) {
53432bee
SZ
560 if (te->tqe_th->th_flags & TH_FIN)
561 p->tqe_th->th_flags |= TH_FIN;
a174690a
JH
562 p->tqe_len += te->tqe_len;
563 m_cat(p->tqe_m, te->tqe_m);
91489f6b
JH
564 tp->encloseblk.rblk_start = p->tqe_th->th_seq;
565 /*
566 * When not reporting a duplicate segment, use
567 * the larger enclosing block as the SACK block.
568 */
c7e6499a 569 if (!(tp->sack_flags & TSACK_F_DUPSEG))
91489f6b 570 tp->reportblk.rblk_start = p->tqe_th->th_seq;
efda3bd0 571 kfree(te, M_TSEGQ);
2d23a8be
MD
572 atomic_add_int(&tcp_reass_qsize, -1);
573 } else {
0f9e45de 574 TAILQ_INSERT_AFTER(&tp->t_segq, p, te, tqe_q);
2d23a8be 575 }
984263bc
MD
576 }
577
578present:
579 /*
580 * Present data to user, advancing rcv_nxt through
581 * completed sequence space.
582 */
583 if (!TCPS_HAVEESTABLISHED(tp->t_state))
584 return (0);
0f9e45de 585 q = TAILQ_FIRST(&tp->t_segq);
61896e3c 586 if (q == NULL || q->tqe_th->th_seq != tp->rcv_nxt)
984263bc 587 return (0);
91489f6b 588 tp->rcv_nxt += q->tqe_len;
c7e6499a 589 if (!(tp->sack_flags & TSACK_F_DUPSEG)) {
91489f6b
JH
590 /* no SACK block to report since ACK advanced */
591 tp->reportblk.rblk_start = tp->reportblk.rblk_end;
592 }
593 /* no enclosing block to report since ACK advanced */
c7e6499a 594 tp->sack_flags &= ~TSACK_F_ENCLOSESEG;
91489f6b 595 flags = q->tqe_th->th_flags & TH_FIN;
0f9e45de
SZ
596 TAILQ_REMOVE(&tp->t_segq, q, tqe_q);
597 KASSERT(TAILQ_EMPTY(&tp->t_segq) ||
598 TAILQ_FIRST(&tp->t_segq)->tqe_th->th_seq != tp->rcv_nxt,
91489f6b 599 ("segment not coalesced"));
6cef7136 600 if (so->so_state & SS_CANTRCVMORE) {
91489f6b 601 m_freem(q->tqe_m);
6cef7136
MD
602 } else {
603 lwkt_gettoken(&so->so_rcv.ssb_token);
6d49aa6f 604 ssb_appendstream(&so->so_rcv, q->tqe_m);
6cef7136
MD
605 lwkt_reltoken(&so->so_rcv.ssb_token);
606 }
efda3bd0 607 kfree(q, M_TSEGQ);
2d23a8be 608 atomic_add_int(&tcp_reass_qsize, -1);
984263bc
MD
609 ND6_HINT(tp);
610 sorwakeup(so);
611 return (flags);
612}
613
614/*
615 * TCP input routine, follows pages 65-76 of the
616 * protocol specification dated September, 1981 very closely.
617 */
618#ifdef INET6
619int
95b22adf 620tcp6_input(struct mbuf **mp, int *offp, int proto)
984263bc 621{
2256ba69 622 struct mbuf *m = *mp;
984263bc
MD
623 struct in6_ifaddr *ia6;
624
625 IP6_EXTHDR_CHECK(m, *offp, sizeof(struct tcphdr), IPPROTO_DONE);
626
627 /*
628 * draft-itojun-ipv6-tcp-to-anycast
629 * better place to put this in?
630 */
631 ia6 = ip6_getdstifaddr(m);
d24ce1dc 632 if (ia6 && (ia6->ia6_flags & IN6_IFF_ANYCAST)) {
984263bc 633 icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR,
f23061d4 634 offsetof(struct ip6_hdr, ip6_dst));
d24ce1dc 635 return (IPPROTO_DONE);
984263bc
MD
636 }
637
002c1265 638 tcp_input(mp, offp, proto);
d24ce1dc 639 return (IPPROTO_DONE);
984263bc
MD
640}
641#endif
642
002c1265
MD
643int
644tcp_input(struct mbuf **mp, int *offp, int proto)
984263bc 645{
002c1265 646 int off0;
2256ba69
RG
647 struct tcphdr *th;
648 struct ip *ip = NULL;
649 struct ipovly *ipov;
650 struct inpcb *inp = NULL;
984263bc
MD
651 u_char *optp = NULL;
652 int optlen = 0;
b1992928
MD
653 int tlen, off;
654 int len = 0;
984263bc 655 int drop_hdrlen;
2256ba69
RG
656 struct tcpcb *tp = NULL;
657 int thflags;
4090d6ff 658 struct socket *so = NULL;
61896e3c 659 int todrop, acked;
27f4bf33
SZ
660 boolean_t ourfinisacked, needoutput = FALSE, delayed_dupack = FALSE;
661 tcp_seq th_dupack = 0; /* XXX gcc warning */
0a832381 662 u_int to_flags = 0; /* XXX gcc warning */
984263bc 663 u_long tiwin;
61896e3c 664 int recvwin;
984263bc 665 struct tcpopt to; /* options in this segment */
984263bc
MD
666 struct sockaddr_in *next_hop = NULL;
667 int rstreason; /* For badport_bandlim accounting purposes */
d371a63a 668 int cpu;
984263bc 669 struct ip6_hdr *ip6 = NULL;
002c1265 670 struct mbuf *m;
984263bc 671#ifdef INET6
d24ce1dc 672 boolean_t isipv6;
984263bc 673#else
d24ce1dc 674 const boolean_t isipv6 = FALSE;
984263bc
MD
675#endif
676#ifdef TCPDEBUG
677 short ostate = 0;
678#endif
679
002c1265
MD
680 off0 = *offp;
681 m = *mp;
682 *mp = NULL;
a00138cb 683
d24ce1dc
JH
684 tcpstat.tcps_rcvtotal++;
685
5de23090
SZ
686 if (m->m_pkthdr.fw_flags & IPFORWARD_MBUF_TAGGED) {
687 struct m_tag *mtag;
688
689 mtag = m_tag_find(m, PACKET_TAG_IPFORWARD, NULL);
690 KKASSERT(mtag != NULL);
691 next_hop = m_tag_data(mtag);
984263bc 692 }
d24ce1dc 693
984263bc 694#ifdef INET6
d24ce1dc 695 isipv6 = (mtod(m, struct ip *)->ip_v == 6) ? TRUE : FALSE;
984263bc 696#endif
984263bc
MD
697
698 if (isipv6) {
699 /* IP6_EXTHDR_CHECK() is already done at tcp6_input() */
700 ip6 = mtod(m, struct ip6_hdr *);
407e896e 701 tlen = (sizeof *ip6) + ntohs(ip6->ip6_plen) - off0;
984263bc
MD
702 if (in6_cksum(m, IPPROTO_TCP, off0, tlen)) {
703 tcpstat.tcps_rcvbadsum++;
704 goto drop;
705 }
706 th = (struct tcphdr *)((caddr_t)ip6 + off0);
707
708 /*
709 * Be proactive about unspecified IPv6 address in source.
710 * As we use all-zero to indicate unbounded/unconnected pcb,
711 * unspecified IPv6 address can be used to confuse us.
712 *
713 * Note that packets with unspecified IPv6 destination is
714 * already dropped in ip6_input.
715 */
716 if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) {
717 /* XXX stat */
718 goto drop;
719 }
720 } else {
721 /*
722 * Get IP and TCP header together in first mbuf.
723 * Note: IP leaves IP header in first mbuf.
724 */
725 if (off0 > sizeof(struct ip)) {
bddf0751 726 ip_stripoptions(m);
984263bc
MD
727 off0 = sizeof(struct ip);
728 }
55d829f8
JH
729 /* already checked and pulled up in ip_demux() */
730 KASSERT(m->m_len >= sizeof(struct tcpiphdr),
61896e3c 731 ("TCP header not in one mbuf: m->m_len %d", m->m_len));
984263bc
MD
732 ip = mtod(m, struct ip *);
733 ipov = (struct ipovly *)ip;
734 th = (struct tcphdr *)((caddr_t)ip + off0);
735 tlen = ip->ip_len;
736
737 if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) {
738 if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR)
739 th->th_sum = m->m_pkthdr.csum_data;
740 else
741 th->th_sum = in_pseudo(ip->ip_src.s_addr,
742 ip->ip_dst.s_addr,
743 htonl(m->m_pkthdr.csum_data +
744 ip->ip_len +
745 IPPROTO_TCP));
746 th->th_sum ^= 0xffff;
747 } else {
748 /*
749 * Checksum extended TCP header and data.
750 */
751 len = sizeof(struct ip) + tlen;
407e896e 752 bzero(ipov->ih_x1, sizeof ipov->ih_x1);
984263bc
MD
753 ipov->ih_len = (u_short)tlen;
754 ipov->ih_len = htons(ipov->ih_len);
755 th->th_sum = in_cksum(m, len);
756 }
757 if (th->th_sum) {
758 tcpstat.tcps_rcvbadsum++;
759 goto drop;
760 }
761#ifdef INET6
762 /* Re-initialization for later version check */
763 ip->ip_v = IPVERSION;
764#endif
765 }
766
767 /*
768 * Check that TCP offset makes sense,
769 * pull out TCP options and adjust length. XXX
770 */
771 off = th->th_off << 2;
55d829f8
JH
772 /* already checked and pulled up in ip_demux() */
773 KASSERT(off >= sizeof(struct tcphdr) && off <= tlen,
61896e3c 774 ("bad TCP data offset %d (tlen %d)", off, tlen));
984263bc
MD
775 tlen -= off; /* tlen is used instead of ti->ti_len */
776 if (off > sizeof(struct tcphdr)) {
777 if (isipv6) {
002c1265 778 IP6_EXTHDR_CHECK(m, off0, off, IPPROTO_DONE);
984263bc
MD
779 ip6 = mtod(m, struct ip6_hdr *);
780 th = (struct tcphdr *)((caddr_t)ip6 + off0);
781 } else {
55d829f8
JH
782 /* already pulled up in ip_demux() */
783 KASSERT(m->m_len >= sizeof(struct ip) + off,
61896e3c
JH
784 ("TCP header and options not in one mbuf: "
785 "m_len %d, off %d", m->m_len, off));
984263bc
MD
786 }
787 optlen = off - sizeof(struct tcphdr);
788 optp = (u_char *)(th + 1);
789 }
790 thflags = th->th_flags;
791
792#ifdef TCP_DROP_SYNFIN
793 /*
794 * If the drop_synfin option is enabled, drop all packets with
795 * both the SYN and FIN bits set. This prevents e.g. nmap from
796 * identifying the TCP/IP stack.
797 *
798 * This is a violation of the TCP specification.
799 */
61896e3c 800 if (drop_synfin && (thflags & (TH_SYN | TH_FIN)) == (TH_SYN | TH_FIN))
984263bc
MD
801 goto drop;
802#endif
803
804 /*
805 * Convert TCP protocol specific fields to host format.
806 */
807 th->th_seq = ntohl(th->th_seq);
808 th->th_ack = ntohl(th->th_ack);
809 th->th_win = ntohs(th->th_win);
810 th->th_urp = ntohs(th->th_urp);
811
812 /*
d24ce1dc 813 * Delay dropping TCP, IP headers, IPv6 ext headers, and TCP options,
984263bc
MD
814 * until after ip6_savecontrol() is called and before other functions
815 * which don't want those proto headers.
816 * Because ip6_savecontrol() is going to parse the mbuf to
817 * search for data to be passed up to user-land, it wants mbuf
818 * parameters to be unchanged.
819 * XXX: the call of ip6_savecontrol() has been obsoleted based on
820 * latest version of the advanced API (20020110).
821 */
822 drop_hdrlen = off0 + off;
823
824 /*
825 * Locate pcb for segment.
826 */
827findpcb:
828 /* IPFIREWALL_FORWARD section */
d24ce1dc 829 if (next_hop != NULL && !isipv6) { /* IPv6 support is not there yet */
984263bc
MD
830 /*
831 * Transparently forwarded. Pretend to be the destination.
d24ce1dc 832 * already got one like this?
984263bc 833 */
6ca1a1cd 834 cpu = mycpu->gd_cpuid;
6ca1a1cd 835 inp = in_pcblookup_hash(&tcbinfo[cpu],
d371a63a 836 ip->ip_src, th->th_sport,
984263bc
MD
837 ip->ip_dst, th->th_dport,
838 0, m->m_pkthdr.rcvif);
839 if (!inp) {
83be63fe
JH
840 /*
841 * It's new. Try to find the ambushing socket.
842 */
843
844 /*
845 * The rest of the ipfw code stores the port in
846 * host order. XXX
847 * (The IP address is still in network order.)
848 */
849 in_port_t dport = next_hop->sin_port ?
850 htons(next_hop->sin_port) :
851 th->th_dport;
852
d371a63a 853 cpu = tcp_addrcpu(ip->ip_src.s_addr, th->th_sport,
83be63fe 854 next_hop->sin_addr.s_addr, dport);
d371a63a 855 inp = in_pcblookup_hash(&tcbinfo[cpu],
984263bc 856 ip->ip_src, th->th_sport,
83be63fe 857 next_hop->sin_addr, dport,
984263bc
MD
858 1, m->m_pkthdr.rcvif);
859 }
860 } else {
6ca1a1cd 861 if (isipv6) {
d371a63a 862 inp = in6_pcblookup_hash(&tcbinfo[0],
984263bc
MD
863 &ip6->ip6_src, th->th_sport,
864 &ip6->ip6_dst, th->th_dport,
865 1, m->m_pkthdr.rcvif);
6ca1a1cd 866 } else {
6ca1a1cd 867 cpu = mycpu->gd_cpuid;
6ca1a1cd 868 inp = in_pcblookup_hash(&tcbinfo[cpu],
984263bc
MD
869 ip->ip_src, th->th_sport,
870 ip->ip_dst, th->th_dport,
871 1, m->m_pkthdr.rcvif);
6ca1a1cd 872 }
984263bc 873 }
984263bc
MD
874
875 /*
876 * If the state is CLOSED (i.e., TCB does not exist) then
877 * all data in the incoming segment is discarded.
878 * If the TCB exists but is in CLOSED state, it is embryonic,
879 * but should either do a listen or a connect soon.
880 */
881 if (inp == NULL) {
882 if (log_in_vain) {
883#ifdef INET6
884 char dbuf[INET6_ADDRSTRLEN+2], sbuf[INET6_ADDRSTRLEN+2];
885#else
1141eb20
JH
886 char dbuf[sizeof "aaa.bbb.ccc.ddd"];
887 char sbuf[sizeof "aaa.bbb.ccc.ddd"];
984263bc
MD
888#endif
889 if (isipv6) {
890 strcpy(dbuf, "[");
984263bc 891 strcat(dbuf, ip6_sprintf(&ip6->ip6_dst));
984263bc 892 strcat(dbuf, "]");
95b22adf
JH
893 strcpy(sbuf, "[");
894 strcat(sbuf, ip6_sprintf(&ip6->ip6_src));
984263bc
MD
895 strcat(sbuf, "]");
896 } else {
897 strcpy(dbuf, inet_ntoa(ip->ip_dst));
898 strcpy(sbuf, inet_ntoa(ip->ip_src));
899 }
900 switch (log_in_vain) {
901 case 1:
61896e3c 902 if (!(thflags & TH_SYN))
984263bc
MD
903 break;
904 case 2:
905 log(LOG_INFO,
906 "Connection attempt to TCP %s:%d "
907 "from %s:%d flags:0x%02x\n",
908 dbuf, ntohs(th->th_dport), sbuf,
909 ntohs(th->th_sport), thflags);
910 break;
911 default:
912 break;
913 }
914 }
d24ce1dc 915 if (blackhole) {
984263bc
MD
916 switch (blackhole) {
917 case 1:
918 if (thflags & TH_SYN)
919 goto drop;
920 break;
921 case 2:
922 goto drop;
923 default:
924 goto drop;
925 }
926 }
927 rstreason = BANDLIM_RST_CLOSEDPORT;
928 goto dropwithreset;
929 }
61896e3c
JH
930
931#ifdef IPSEC
932 if (isipv6) {
933 if (ipsec6_in_reject_so(m, inp->inp_socket)) {
934 ipsec6stat.in_polvio++;
935 goto drop;
936 }
937 } else {
938 if (ipsec4_in_reject_so(m, inp->inp_socket)) {
939 ipsecstat.in_polvio++;
940 goto drop;
941 }
942 }
943#endif
944#ifdef FAST_IPSEC
945 if (isipv6) {
946 if (ipsec6_in_reject(m, inp))
947 goto drop;
948 } else {
949 if (ipsec4_in_reject(m, inp))
950 goto drop;
951 }
952#endif
95926362
MD
953 /* Check the minimum TTL for socket. */
954#ifdef INET6
955 if ((isipv6 ? ip6->ip6_hlim : ip->ip_ttl) < inp->inp_ip_minttl)
956 goto drop;
957#endif
61896e3c 958
984263bc
MD
959 tp = intotcpcb(inp);
960 if (tp == NULL) {
961 rstreason = BANDLIM_RST_CLOSEDPORT;
962 goto dropwithreset;
963 }
eb594563 964 if (tp->t_state <= TCPS_CLOSED)
984263bc
MD
965 goto drop;
966
984263bc 967 so = inp->inp_socket;
47654766 968
984263bc 969#ifdef TCPDEBUG
47654766
JH
970 if (so->so_options & SO_DEBUG) {
971 ostate = tp->t_state;
972 if (isipv6)
95b22adf 973 bcopy(ip6, tcp_saveipgen, sizeof(*ip6));
47654766 974 else
95b22adf 975 bcopy(ip, tcp_saveipgen, sizeof(*ip));
47654766
JH
976 tcp_savetcp = *th;
977 }
984263bc 978#endif
47654766 979
407e896e 980 bzero(&to, sizeof to);
d24ce1dc 981
47654766
JH
982 if (so->so_options & SO_ACCEPTCONN) {
983 struct in_conninfo inc;
984
984263bc 985#ifdef INET6
d24ce1dc 986 inc.inc_isipv6 = (isipv6 == TRUE);
984263bc
MD
987#endif
988 if (isipv6) {
989 inc.inc6_faddr = ip6->ip6_src;
990 inc.inc6_laddr = ip6->ip6_dst;
991 inc.inc6_route.ro_rt = NULL; /* XXX */
992 } else {
993 inc.inc_faddr = ip->ip_src;
994 inc.inc_laddr = ip->ip_dst;
995 inc.inc_route.ro_rt = NULL; /* XXX */
996 }
997 inc.inc_fport = th->th_sport;
998 inc.inc_lport = th->th_dport;
999
61896e3c
JH
1000 /*
1001 * If the state is LISTEN then ignore segment if it contains
984263bc
MD
1002 * a RST. If the segment contains an ACK then it is bad and
1003 * send a RST. If it does not contain a SYN then it is not
1004 * interesting; drop it.
1005 *
1006 * If the state is SYN_RECEIVED (syncache) and seg contains
1007 * an ACK, but not for our SYN/ACK, send a RST. If the seg
1008 * contains a RST, check the sequence number to see if it
1009 * is a valid reset segment.
1010 */
61896e3c
JH
1011 if ((thflags & (TH_RST | TH_ACK | TH_SYN)) != TH_SYN) {
1012 if ((thflags & (TH_RST | TH_ACK | TH_SYN)) == TH_ACK) {
984263bc
MD
1013 if (!syncache_expand(&inc, th, &so, m)) {
1014 /*
1015 * No syncache entry, or ACK was not
1016 * for our SYN/ACK. Send a RST.
1017 */
1018 tcpstat.tcps_badsyn++;
1019 rstreason = BANDLIM_RST_OPENPORT;
1020 goto dropwithreset;
1021 }
2d23a8be
MD
1022
1023 /*
1024 * Could not complete 3-way handshake,
1025 * connection is being closed down, and
1026 * syncache will free mbuf.
1027 */
984263bc 1028 if (so == NULL)
002c1265 1029 return(IPPROTO_DONE);
2d23a8be
MD
1030
1031 /*
1032 * We must be in the correct protocol thread
1033 * for this connection.
1034 */
1035 KKASSERT(so->so_port == &curthread->td_msgport);
1036
984263bc
MD
1037 /*
1038 * Socket is created in state SYN_RECEIVED.
1039 * Continue processing segment.
1040 */
ed894f8c 1041 inp = so->so_pcb;
984263bc
MD
1042 tp = intotcpcb(inp);
1043 /*
1044 * This is what would have happened in
1045 * tcp_output() when the SYN,ACK was sent.
1046 */
1047 tp->snd_up = tp->snd_una;
1048 tp->snd_max = tp->snd_nxt = tp->iss + 1;
1049 tp->last_ack_sent = tp->rcv_nxt;
df1d2774 1050
984263bc
MD
1051 goto after_listen;
1052 }
1053 if (thflags & TH_RST) {
1054 syncache_chkrst(&inc, th);
1055 goto drop;
1056 }
1057 if (thflags & TH_ACK) {
1058 syncache_badack(&inc);
1059 tcpstat.tcps_badsyn++;
1060 rstreason = BANDLIM_RST_OPENPORT;
1061 goto dropwithreset;
1062 }
1063 goto drop;
1064 }
1065
1066 /*
61896e3c 1067 * Segment's flags are (SYN) or (SYN | FIN).
984263bc
MD
1068 */
1069#ifdef INET6
1070 /*
1071 * If deprecated address is forbidden,
1072 * we do not accept SYN to deprecated interface
1073 * address to prevent any new inbound connection from
1074 * getting established.
1075 * When we do not accept SYN, we send a TCP RST,
1076 * with deprecated source address (instead of dropping
1077 * it). We compromise it as it is much better for peer
1078 * to send a RST, and RST will be the final packet
1079 * for the exchange.
1080 *
1081 * If we do not forbid deprecated addresses, we accept
1082 * the SYN packet. RFC2462 does not suggest dropping
1083 * SYN in this case.
1084 * If we decipher RFC2462 5.5.4, it says like this:
1085 * 1. use of deprecated addr with existing
1086 * communication is okay - "SHOULD continue to be
1087 * used"
1088 * 2. use of it with new communication:
1089 * (2a) "SHOULD NOT be used if alternate address
61896e3c 1090 * with sufficient scope is available"
984263bc
MD
1091 * (2b) nothing mentioned otherwise.
1092 * Here we fall into (2b) case as we have no choice in
1093 * our source address selection - we must obey the peer.
1094 *
1095 * The wording in RFC2462 is confusing, and there are
1096 * multiple description text for deprecated address
1097 * handling - worse, they are not exactly the same.
1098 * I believe 5.5.4 is the best one, so we follow 5.5.4.
1099 */
1100 if (isipv6 && !ip6_use_deprecated) {
1101 struct in6_ifaddr *ia6;
1102
1103 if ((ia6 = ip6_getdstifaddr(m)) &&
1104 (ia6->ia6_flags & IN6_IFF_DEPRECATED)) {
1105 tp = NULL;
1106 rstreason = BANDLIM_RST_OPENPORT;
1107 goto dropwithreset;
1108 }
1109 }
1110#endif
1111 /*
1112 * If it is from this socket, drop it, it must be forged.
1113 * Don't bother responding if the destination was a broadcast.
1114 */
1115 if (th->th_dport == th->th_sport) {
1116 if (isipv6) {
1117 if (IN6_ARE_ADDR_EQUAL(&ip6->ip6_dst,
1118 &ip6->ip6_src))
1119 goto drop;
1120 } else {
1121 if (ip->ip_dst.s_addr == ip->ip_src.s_addr)
1122 goto drop;
1123 }
1124 }
1125 /*
1126 * RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN
1127 *
1128 * Note that it is quite possible to receive unicast
1129 * link-layer packets with a broadcast IP address. Use
1130 * in_broadcast() to find them.
1131 */
61896e3c 1132 if (m->m_flags & (M_BCAST | M_MCAST))
984263bc
MD
1133 goto drop;
1134 if (isipv6) {
1135 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
1136 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src))
1137 goto drop;
1138 } else {
1139 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) ||
1140 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
1141 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) ||
1142 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif))
1143 goto drop;
1144 }
1145 /*
1146 * SYN appears to be valid; create compressed TCP state
1147 * for syncache, or perform t/tcp connection.
1148 */
1149 if (so->so_qlen <= so->so_qlimit) {
6c1bbf57 1150 tcp_dooptions(&to, optp, optlen, TRUE, th->th_ack);
b09567cc 1151 if (!syncache_add(&inc, &to, th, so, m))
984263bc 1152 goto drop;
2d23a8be
MD
1153
1154 /*
1155 * Entry added to syncache, mbuf used to
1156 * send SYN,ACK packet.
1157 */
b09567cc 1158 return(IPPROTO_DONE);
984263bc
MD
1159 }
1160 goto drop;
1161 }
984263bc 1162
2d23a8be
MD
1163after_listen:
1164 /*
1165 * Should not happen - syncache should pick up these connections.
1166 *
1167 * Once we are past handling listen sockets we must be in the
1168 * correct protocol processing thread.
1169 */
61896e3c 1170 KASSERT(tp->t_state != TCPS_LISTEN, ("tcp_input: TCPS_LISTEN state"));
2d23a8be 1171 KKASSERT(so->so_port == &curthread->td_msgport);
984263bc 1172
df1d2774
SZ
1173 /* Unscale the window into a 32-bit value. */
1174 if (!(thflags & TH_SYN))
1175 tiwin = th->th_win << tp->snd_scale;
1176 else
1177 tiwin = th->th_win;
1178
984263bc 1179 /*
5b0b9fa5
PA
1180 * This is the second part of the MSS DoS prevention code (after
1181 * minmss on the sending side) and it deals with too many too small
1182 * tcp packets in a too short timeframe (1 second).
1183 *
153d34ac
MD
1184 * XXX Removed. This code was crap. It does not scale to network
1185 * speed, and default values break NFS. Gone.
5b0b9fa5 1186 */
153d34ac 1187 /* REMOVED */
5b0b9fa5
PA
1188
1189 /*
984263bc 1190 * Segment received on connection.
efca2b8e
MD
1191 *
1192 * Reset idle time and keep-alive timer. Don't waste time if less
0ecd93f9 1193 * then a second has elapsed.
984263bc 1194 */
0ecd93f9
MD
1195 if ((int)(ticks - tp->t_rcvtime) > hz)
1196 tcp_timer_keep_activity(tp, thflags);
984263bc
MD
1197
1198 /*
1199 * Process options.
1200 * XXX this is tradtitional behavior, may need to be cleaned up.
1201 */
6c1bbf57 1202 tcp_dooptions(&to, optp, optlen, (thflags & TH_SYN) != 0, th->th_ack);
ad0af98b 1203 if (tp->t_state == TCPS_SYN_SENT && (thflags & TH_SYN)) {
df1d2774 1204 if ((to.to_flags & TOF_SCALE) && (tp->t_flags & TF_REQ_SCALE)) {
984263bc 1205 tp->t_flags |= TF_RCVD_SCALE;
df1d2774 1206 tp->snd_scale = to.to_requested_s_scale;
984263bc 1207 }
df1d2774
SZ
1208
1209 /*
1210 * Initial send window; will be updated upon next ACK
1211 */
1212 tp->snd_wnd = th->th_win;
1213
984263bc
MD
1214 if (to.to_flags & TOF_TS) {
1215 tp->t_flags |= TF_RCVD_TSTMP;
1216 tp->ts_recent = to.to_tsval;
1217 tp->ts_recent_age = ticks;
1218 }
f34fd0f2
SZ
1219 if (!(to.to_flags & TOF_MSS))
1220 to.to_mss = 0;
1221 tcp_mss(tp, to.to_mss);
91489f6b
JH
1222 /*
1223 * Only set the TF_SACK_PERMITTED per-connection flag
1224 * if we got a SACK_PERMITTED option from the other side
1225 * and the global tcp_do_sack variable is true.
1226 */
1227 if (tcp_do_sack && (to.to_flags & TOF_SACK_PERMITTED))
1228 tp->t_flags |= TF_SACK_PERMITTED;
984263bc
MD
1229 }
1230
1231 /*
1232 * Header prediction: check for the two common cases
1233 * of a uni-directional data xfer. If the packet has
1234 * no control flags, is in-sequence, the window didn't
1235 * change and we're not retransmitting, it's a
1236 * candidate. If the length is zero and the ack moved
1237 * forward, we're the sender side of the xfer. Just
1238 * free the data acked & wake any higher level process
1239 * that was blocked waiting for space. If the length
1240 * is non-zero and the ack didn't move, we're the
1241 * receiver side. If we're getting packets in-order
1242 * (the reassembly queue is empty), add the data to
1243 * the socket buffer and note that we need a delayed ack.
1244 * Make sure that the hidden state-flags are also off.
1245 * Since we check for TCPS_ESTABLISHED above, it can only
1246 * be TH_NEEDSYN.
1247 */
1248 if (tp->t_state == TCPS_ESTABLISHED &&
1249 (thflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK &&
61896e3c
JH
1250 !(tp->t_flags & (TF_NEEDSYN | TF_NEEDFIN)) &&
1251 (!(to.to_flags & TOF_TS) ||
984263bc 1252 TSTMP_GEQ(to.to_tsval, tp->ts_recent)) &&
984263bc 1253 th->th_seq == tp->rcv_nxt &&
984263bc
MD
1254 tp->snd_nxt == tp->snd_max) {
1255
1256 /*
1257 * If last ACK falls within this segment's sequence numbers,
1258 * record the timestamp.
1259 * NOTE that the test is modified according to the latest
1260 * proposal of the tcplw@cray.com list (Braden 1993/04/26).
1261 */
61896e3c 1262 if ((to.to_flags & TOF_TS) &&
984263bc
MD
1263 SEQ_LEQ(th->th_seq, tp->last_ack_sent)) {
1264 tp->ts_recent_age = ticks;
1265 tp->ts_recent = to.to_tsval;
1266 }
1267
1268 if (tlen == 0) {
1269 if (SEQ_GT(th->th_ack, tp->snd_una) &&
1270 SEQ_LEQ(th->th_ack, tp->snd_max) &&
1271 tp->snd_cwnd >= tp->snd_wnd &&
95b22adf 1272 !IN_FASTRECOVERY(tp)) {
984263bc 1273 /*
be23faf1 1274 * This is a pure ack for outstanding data.
984263bc
MD
1275 */
1276 ++tcpstat.tcps_predack;
1277 /*
1278 * "bad retransmit" recovery
bfdb979e
JH
1279 *
1280 * If Eifel detection applies, then
1281 * it is deterministic, so use it
1282 * unconditionally over the old heuristic.
1283 * Otherwise, fall back to the old heuristic.
984263bc 1284 */
bfdb979e
JH
1285 if (tcp_do_eifel_detect &&
1286 (to.to_flags & TOF_TS) && to.to_tsecr &&
1c8b7a61 1287 (tp->rxt_flags & TRXT_F_FIRSTACCACK)) {
bfdb979e
JH
1288 /* Eifel detection applicable. */
1289 if (to.to_tsecr < tp->t_rexmtTS) {
1290 tcp_revert_congestion_state(tp);
1291 ++tcpstat.tcps_eifeldetected;
928c3291
SZ
1292 if (tp->t_rxtshift != 1 ||
1293 ticks >= tp->t_badrxtwin)
1294 ++tcpstat.tcps_rttcantdetect;
bfdb979e
JH
1295 }
1296 } else if (tp->t_rxtshift == 1 &&
1297 ticks < tp->t_badrxtwin) {
1298 tcp_revert_congestion_state(tp);
1299 ++tcpstat.tcps_rttdetected;
984263bc 1300 }
1c8b7a61
SZ
1301 tp->rxt_flags &= ~(TRXT_F_FIRSTACCACK |
1302 TRXT_F_FASTREXMT | TRXT_F_EARLYREXMT);
984263bc
MD
1303 /*
1304 * Recalculate the retransmit timer / rtt.
1305 *
d24ce1dc 1306 * Some machines (certain windows boxes)
984263bc
MD
1307 * send broken timestamp replies during the
1308 * SYN+ACK phase, ignore timestamps of 0.
1309 */
95b22adf 1310 if ((to.to_flags & TOF_TS) && to.to_tsecr) {
984263bc 1311 tcp_xmit_timer(tp,
073ec6c4
SZ
1312 ticks - to.to_tsecr + 1,
1313 th->th_ack);
984263bc 1314 } else if (tp->t_rtttime &&
95b22adf 1315 SEQ_GT(th->th_ack, tp->t_rtseq)) {
984263bc 1316 tcp_xmit_timer(tp,
073ec6c4
SZ
1317 ticks - tp->t_rtttime,
1318 th->th_ack);
984263bc
MD
1319 }
1320 tcp_xmit_bandwidth_limit(tp, th->th_ack);
1321 acked = th->th_ack - tp->snd_una;
1322 tcpstat.tcps_rcvackpack++;
1323 tcpstat.tcps_rcvackbyte += acked;
6d49aa6f 1324 sbdrop(&so->so_snd.sb, acked);
cfb3f3f4 1325 tp->snd_recover = th->th_ack - 1;
9845754e 1326 tp->snd_una = th->th_ack;
984263bc 1327 tp->t_dupacks = 0;
df9d7670
JH
1328 /*
1329 * Update window information.
1330 */
1331 if (tiwin != tp->snd_wnd &&
1332 acceptable_window_update(tp, th, tiwin)) {
1333 /* keep track of pure window updates */
1334 if (tp->snd_wl2 == th->th_ack &&
1335 tiwin > tp->snd_wnd)
1336 tcpstat.tcps_rcvwinupd++;
1337 tp->snd_wnd = tiwin;
1338 tp->snd_wl1 = th->th_seq;
1339 tp->snd_wl2 = th->th_ack;
1340 if (tp->snd_wnd > tp->max_sndwnd)
1341 tp->max_sndwnd = tp->snd_wnd;
1342 }
984263bc
MD
1343 m_freem(m);
1344 ND6_HINT(tp); /* some progress has been done */
984263bc
MD
1345 /*
1346 * If all outstanding data are acked, stop
1347 * retransmit timer, otherwise restart timer
1348 * using current (possibly backed-off) value.
1349 * If process is waiting for space,
1350 * wakeup/selwakeup/signal. If data
1351 * are ready to send, let tcp_output
1352 * decide between more output or persist.
1353 */
a48c5dd5
SZ
1354 if (tp->snd_una == tp->snd_max) {
1355 tcp_callout_stop(tp, tp->tt_rexmt);
1356 } else if (!tcp_callout_active(tp,
1357 tp->tt_persist)) {
1358 tcp_callout_reset(tp, tp->tt_rexmt,
1359 tp->t_rxtcur, tcp_timer_rexmt);
1360 }
984263bc 1361 sowwakeup(so);
2fb3a851
SZ
1362 if (so->so_snd.ssb_cc > 0 &&
1363 !tcp_output_pending(tp))
1364 tcp_output_fair(tp);
002c1265 1365 return(IPPROTO_DONE);
984263bc 1366 }
df9d7670
JH
1367 } else if (tiwin == tp->snd_wnd &&
1368 th->th_ack == tp->snd_una &&
0f9e45de 1369 TAILQ_EMPTY(&tp->t_segq) &&
6d49aa6f 1370 tlen <= ssb_space(&so->so_rcv)) {
46e92930 1371 u_long newsize = 0; /* automatic sockbuf scaling */
984263bc 1372 /*
be23faf1 1373 * This is a pure, in-sequence data packet
984263bc
MD
1374 * with nothing on the reassembly queue and
1375 * we have enough buffer space to take it.
1376 */
1377 ++tcpstat.tcps_preddat;
1378 tp->rcv_nxt += tlen;
1379 tcpstat.tcps_rcvpack++;
1380 tcpstat.tcps_rcvbyte += tlen;
1381 ND6_HINT(tp); /* some progress has been done */
5b0b9fa5
PA
1382 /*
1383 * Automatic sizing of receive socket buffer. Often the send
1384 * buffer size is not optimally adjusted to the actual network
1385 * conditions at hand (delay bandwidth product). Setting the
1386 * buffer size too small limits throughput on links with high
1387 * bandwidth and high delay (eg. trans-continental/oceanic links).
1388 *
1389 * On the receive side the socket buffer memory is only rarely
1390 * used to any significant extent. This allows us to be much
1391 * more aggressive in scaling the receive socket buffer. For
1392 * the case that the buffer space is actually used to a large
1393 * extent and we run out of kernel memory we can simply drop
1394 * the new segments; TCP on the sender will just retransmit it
1395 * later. Setting the buffer size too big may only consume too
1396 * much kernel memory if the application doesn't read() from
1397 * the socket or packet loss or reordering makes use of the
1398 * reassembly queue.
1399 *
1400 * The criteria to step up the receive buffer one notch are:
1401 * 1. the number of bytes received during the time it takes
1402 * one timestamp to be reflected back to us (the RTT);
1403 * 2. received bytes per RTT is within seven eighth of the
1404 * current socket buffer size;
1405 * 3. receive buffer size has not hit maximal automatic size;
1406 *
1407 * This algorithm does one step per RTT at most and only if
1408 * we receive a bulk stream w/o packet losses or reorderings.
1409 * Shrinking the buffer during idle times is not necessary as
1410 * it doesn't consume any memory when idle.
1411 *
1412 * TODO: Only step up if the application is actually serving
1413 * the buffer to better manage the socket buffer resources.
1414 */
1415 if (tcp_do_autorcvbuf &&
1416 to.to_tsecr &&
1417 (so->so_rcv.ssb_flags & SSB_AUTOSIZE)) {
1418 if (to.to_tsecr > tp->rfbuf_ts &&
1419 to.to_tsecr - tp->rfbuf_ts < hz) {
1420 if (tp->rfbuf_cnt >
1421 (so->so_rcv.ssb_hiwat / 8 * 7) &&
1422 so->so_rcv.ssb_hiwat <
1423 tcp_autorcvbuf_max) {
1424 newsize =
46e92930
MD
1425 ulmin(so->so_rcv.ssb_hiwat +
1426 tcp_autorcvbuf_inc,
1427 tcp_autorcvbuf_max);
5b0b9fa5
PA
1428 }
1429 /* Start over with next RTT. */
1430 tp->rfbuf_ts = 0;
1431 tp->rfbuf_cnt = 0;
1432 } else
1433 tp->rfbuf_cnt += tlen; /* add up */
1434 }
984263bc
MD
1435 /*
1436 * Add data to socket buffer.
1437 */
1438 if (so->so_state & SS_CANTRCVMORE) {
1439 m_freem(m);
1440 } else {
5b0b9fa5 1441 /*
46e92930
MD
1442 * Set new socket buffer size, give up when
1443 * limit is reached.
1444 *
1445 * Adjusting the size can mess up ACK
1446 * sequencing when pure window updates are
1447 * being avoided (which is the default),
1448 * so force an ack.
5b0b9fa5 1449 */
6cef7136 1450 lwkt_gettoken(&so->so_rcv.ssb_token);
46e92930
MD
1451 if (newsize) {
1452 tp->t_flags |= TF_RXRESIZED;
5b0b9fa5 1453 if (!ssb_reserve(&so->so_rcv, newsize,
46e92930 1454 so, NULL)) {
14343ad3 1455 atomic_clear_int(&so->so_rcv.ssb_flags, SSB_AUTOSIZE);
46e92930
MD
1456 }
1457 if (newsize >=
1458 (TCP_MAXWIN << tp->rcv_scale)) {
14343ad3 1459 atomic_clear_int(&so->so_rcv.ssb_flags, SSB_AUTOSIZE);
46e92930
MD
1460 }
1461 }
09cf73e0 1462 m_adj(m, drop_hdrlen); /* delayed header drop */
6d49aa6f 1463 ssb_appendstream(&so->so_rcv, m);
6cef7136 1464 lwkt_reltoken(&so->so_rcv.ssb_token);
984263bc
MD
1465 }
1466 sorwakeup(so);
2b1ce38a
MD
1467 /*
1468 * This code is responsible for most of the ACKs
1469 * the TCP stack sends back after receiving a data
1470 * packet. Note that the DELAY_ACK check fails if
1471 * the delack timer is already running, which results
1472 * in an ack being sent every other packet (which is
1473 * what we want).
72b37eeb
MD
1474 *
1475 * We then further aggregate acks by not actually
1476 * sending one until the protocol thread has completed
1477 * processing the current backlog of packets. This
1478 * does not delay the ack any further, but allows us
1479 * to take advantage of the packet aggregation that
1480 * high speed NICs do (usually blocks of 8-10 packets)
1481 * to send a single ack rather then four or five acks,
1482 * greatly reducing the ack rate, the return channel
1483 * bandwidth, and the protocol overhead on both ends.
1484 *
1485 * Since this also has the effect of slowing down
1486 * the exponential slow-start ramp-up, systems with
1487 * very large bandwidth-delay products might want
1488 * to turn the feature off.
2b1ce38a 1489 */
984263bc 1490 if (DELAY_ACK(tp)) {
a48c5dd5
SZ
1491 tcp_callout_reset(tp, tp->tt_delack,
1492 tcp_delacktime, tcp_timer_delack);
72b37eeb 1493 } else if (tcp_aggregate_acks) {
984263bc 1494 tp->t_flags |= TF_ACKNOW;
61896e3c 1495 if (!(tp->t_flags & TF_ONOUTPUTQ)) {
2b1ce38a
MD
1496 tp->t_flags |= TF_ONOUTPUTQ;
1497 tp->tt_cpu = mycpu->gd_cpuid;
1498 TAILQ_INSERT_TAIL(
1499 &tcpcbackq[tp->tt_cpu],
1500 tp, t_outputq);
1501 }
72b37eeb
MD
1502 } else {
1503 tp->t_flags |= TF_ACKNOW;
1504 tcp_output(tp);
984263bc 1505 }
002c1265 1506 return(IPPROTO_DONE);
984263bc
MD
1507 }
1508 }
1509
1510 /*
1511 * Calculate amount of space in receive window,
1512 * and then do TCP input processing.
1513 * Receive window is amount of space in rcv queue,
1514 * but not less than advertised window.
1515 */
6d49aa6f 1516 recvwin = ssb_space(&so->so_rcv);
61896e3c
JH
1517 if (recvwin < 0)
1518 recvwin = 0;
1519 tp->rcv_wnd = imax(recvwin, (int)(tp->rcv_adv - tp->rcv_nxt));
984263bc 1520
5b0b9fa5
PA
1521 /* Reset receive buffer auto scaling when not in bulk receive mode. */
1522 tp->rfbuf_ts = 0;
1523 tp->rfbuf_cnt = 0;
1524
984263bc 1525 switch (tp->t_state) {
984263bc
MD
1526 /*
1527 * If the state is SYN_RECEIVED:
1528 * if seg contains an ACK, but not for our SYN/ACK, send a RST.
1529 */
1530 case TCPS_SYN_RECEIVED:
1531 if ((thflags & TH_ACK) &&
1532 (SEQ_LEQ(th->th_ack, tp->snd_una) ||
1533 SEQ_GT(th->th_ack, tp->snd_max))) {
1534 rstreason = BANDLIM_RST_OPENPORT;
1535 goto dropwithreset;
1536 }
1537 break;
1538
1539 /*
1540 * If the state is SYN_SENT:
1541 * if seg contains an ACK, but not for our SYN, drop the input.
1542 * if seg contains a RST, then drop the connection.
1543 * if seg does not contain SYN, then drop it.
1544 * Otherwise this is an acceptable SYN segment
1545 * initialize tp->rcv_nxt and tp->irs
1546 * if seg contains ack then advance tp->snd_una
1547 * if SYN has been acked change to ESTABLISHED else SYN_RCVD state
1548 * arrange for segment to be acked (eventually)
1549 * continue processing rest of data/controls, beginning with URG
1550 */
1551 case TCPS_SYN_SENT:
984263bc
MD
1552 if ((thflags & TH_ACK) &&
1553 (SEQ_LEQ(th->th_ack, tp->iss) ||
1554 SEQ_GT(th->th_ack, tp->snd_max))) {
27b8aee3
AE
1555 rstreason = BANDLIM_UNLIMITED;
1556 goto dropwithreset;
984263bc
MD
1557 }
1558 if (thflags & TH_RST) {
1559 if (thflags & TH_ACK)
1560 tp = tcp_drop(tp, ECONNREFUSED);
1561 goto drop;
1562 }
61896e3c 1563 if (!(thflags & TH_SYN))
984263bc 1564 goto drop;
984263bc
MD
1565
1566 tp->irs = th->th_seq;
1567 tcp_rcvseqinit(tp);
1568 if (thflags & TH_ACK) {
27b8aee3 1569 /* Our SYN was acked. */
984263bc
MD
1570 tcpstat.tcps_connects++;
1571 soisconnected(so);
1572 /* Do window scaling on this connection? */
61896e3c 1573 if ((tp->t_flags & (TF_RCVD_SCALE | TF_REQ_SCALE)) ==
df1d2774 1574 (TF_RCVD_SCALE | TF_REQ_SCALE))
984263bc 1575 tp->rcv_scale = tp->request_r_scale;
984263bc
MD
1576 tp->rcv_adv += tp->rcv_wnd;
1577 tp->snd_una++; /* SYN is acked */
a48c5dd5 1578 tcp_callout_stop(tp, tp->tt_rexmt);
984263bc
MD
1579 /*
1580 * If there's data, delay ACK; if there's also a FIN
1581 * ACKNOW will be turned on later.
1582 */
a48c5dd5
SZ
1583 if (DELAY_ACK(tp) && tlen != 0) {
1584 tcp_callout_reset(tp, tp->tt_delack,
1585 tcp_delacktime, tcp_timer_delack);
1586 } else {
984263bc 1587 tp->t_flags |= TF_ACKNOW;
a48c5dd5 1588 }
984263bc
MD
1589 /*
1590 * Received <SYN,ACK> in SYN_SENT[*] state.
1591 * Transitions:
1592 * SYN_SENT --> ESTABLISHED
1593 * SYN_SENT* --> FIN_WAIT_1
1594 */
1595 tp->t_starttime = ticks;
1596 if (tp->t_flags & TF_NEEDFIN) {
1597 tp->t_state = TCPS_FIN_WAIT_1;
1598 tp->t_flags &= ~TF_NEEDFIN;
1599 thflags &= ~TH_SYN;
1600 } else {
8651f7f8 1601 tcp_established(tp);
984263bc
MD
1602 }
1603 } else {
1604 /*
95b22adf 1605 * Received initial SYN in SYN-SENT[*] state =>
27b8aee3
AE
1606 * simultaneous open.
1607 * Do 3-way handshake:
61896e3c
JH
1608 * SYN-SENT -> SYN-RECEIVED
1609 * SYN-SENT* -> SYN-RECEIVED*
95b22adf 1610 */
984263bc 1611 tp->t_flags |= TF_ACKNOW;
a48c5dd5 1612 tcp_callout_stop(tp, tp->tt_rexmt);
27b8aee3 1613 tp->t_state = TCPS_SYN_RECEIVED;
984263bc
MD
1614 }
1615
984263bc
MD
1616 /*
1617 * Advance th->th_seq to correspond to first data byte.
1618 * If data, trim to stay within window,
1619 * dropping FIN if necessary.
1620 */
1621 th->th_seq++;
1622 if (tlen > tp->rcv_wnd) {
1623 todrop = tlen - tp->rcv_wnd;
1624 m_adj(m, -todrop);
1625 tlen = tp->rcv_wnd;
1626 thflags &= ~TH_FIN;
1627 tcpstat.tcps_rcvpackafterwin++;
1628 tcpstat.tcps_rcvbyteafterwin += todrop;
1629 }
1630 tp->snd_wl1 = th->th_seq - 1;
1631 tp->rcv_up = th->th_seq;
1632 /*
1633 * Client side of transaction: already sent SYN and data.
1634 * If the remote host used T/TCP to validate the SYN,
1635 * our data will be ACK'd; if so, enter normal data segment
1636 * processing in the middle of step 5, ack processing.
1637 * Otherwise, goto step 6.
1638 */
95b22adf 1639 if (thflags & TH_ACK)
984263bc
MD
1640 goto process_ACK;
1641
1642 goto step6;
1643
1644 /*
1645 * If the state is LAST_ACK or CLOSING or TIME_WAIT:
27b8aee3 1646 * do normal processing (we no longer bother with T/TCP).
984263bc
MD
1647 */
1648 case TCPS_LAST_ACK:
1649 case TCPS_CLOSING:
1650 case TCPS_TIME_WAIT:
95b22adf 1651 break; /* continue normal processing */
984263bc
MD
1652 }
1653
1654 /*
1655 * States other than LISTEN or SYN_SENT.
1656 * First check the RST flag and sequence number since reset segments
1657 * are exempt from the timestamp and connection count tests. This
1658 * fixes a bug introduced by the Stevens, vol. 2, p. 960 bugfix
1659 * below which allowed reset segments in half the sequence space
1660 * to fall though and be processed (which gives forged reset
1661 * segments with a random sequence number a 50 percent chance of
1662 * killing a connection).
1663 * Then check timestamp, if present.
1664 * Then check the connection count, if present.
1665 * Then check that at least some bytes of segment are within
1666 * receive window. If segment begins before rcv_nxt,
1667 * drop leading data (and SYN); if nothing left, just ack.
1668 *
1669 *
1670 * If the RST bit is set, check the sequence number to see
1671 * if this is a valid reset segment.
1672 * RFC 793 page 37:
1673 * In all states except SYN-SENT, all reset (RST) segments
1674 * are validated by checking their SEQ-fields. A reset is
1675 * valid if its sequence number is in the window.
1676 * Note: this does not take into account delayed ACKs, so
1677 * we should test against last_ack_sent instead of rcv_nxt.
1678 * The sequence number in the reset segment is normally an
91489f6b 1679 * echo of our outgoing acknowledgement numbers, but some hosts
984263bc
MD
1680 * send a reset with the sequence number at the rightmost edge
1681 * of our receive window, and we have to handle this case.
1682 * If we have multiple segments in flight, the intial reset
1683 * segment sequence numbers will be to the left of last_ack_sent,
1684 * but they will eventually catch up.
1685 * In any case, it never made sense to trim reset segments to
1686 * fit the receive window since RFC 1122 says:
1687 * 4.2.2.12 RST Segment: RFC-793 Section 3.4
1688 *
1689 * A TCP SHOULD allow a received RST segment to include data.
1690 *
1691 * DISCUSSION
61896e3c
JH
1692 * It has been suggested that a RST segment could contain
1693 * ASCII text that encoded and explained the cause of the
91489f6b 1694 * RST. No standard has yet been established for such
61896e3c 1695 * data.
984263bc
MD
1696 *
1697 * If the reset segment passes the sequence number test examine
1698 * the state:
1699 * SYN_RECEIVED STATE:
1700 * If passive open, return to LISTEN state.
1701 * If active open, inform user that connection was refused.
1702 * ESTABLISHED, FIN_WAIT_1, FIN_WAIT_2, CLOSE_WAIT STATES:
1703 * Inform user that connection was reset, and close tcb.
1704 * CLOSING, LAST_ACK STATES:
1705 * Close the tcb.
1706 * TIME_WAIT STATE:
1707 * Drop the segment - see Stevens, vol. 2, p. 964 and
61896e3c 1708 * RFC 1337.
984263bc
MD
1709 */
1710 if (thflags & TH_RST) {
1711 if (SEQ_GEQ(th->th_seq, tp->last_ack_sent) &&
d4dbb5be 1712 SEQ_LEQ(th->th_seq, tp->last_ack_sent + tp->rcv_wnd)) {
984263bc
MD
1713 switch (tp->t_state) {
1714
1715 case TCPS_SYN_RECEIVED:
1716 so->so_error = ECONNREFUSED;
1717 goto close;
1718
1719 case TCPS_ESTABLISHED:
1720 case TCPS_FIN_WAIT_1:
1721 case TCPS_FIN_WAIT_2:
1722 case TCPS_CLOSE_WAIT:
1723 so->so_error = ECONNRESET;
1724 close:
1725 tp->t_state = TCPS_CLOSED;
1726 tcpstat.tcps_drops++;
1727 tp = tcp_close(tp);
1728 break;
1729
1730 case TCPS_CLOSING:
1731 case TCPS_LAST_ACK:
1732 tp = tcp_close(tp);
1733 break;
1734
1735 case TCPS_TIME_WAIT:
1736 break;
1737 }
1738 }
1739 goto drop;
1740 }
1741
1742 /*
1743 * RFC 1323 PAWS: If we have a timestamp reply on this segment
1744 * and it's less than ts_recent, drop it.
1745 */
61896e3c 1746 if ((to.to_flags & TOF_TS) && tp->ts_recent != 0 &&
984263bc 1747 TSTMP_LT(to.to_tsval, tp->ts_recent)) {
984263bc
MD
1748 /* Check to see if ts_recent is over 24 days old. */
1749 if ((int)(ticks - tp->ts_recent_age) > TCP_PAWS_IDLE) {
1750 /*
1751 * Invalidate ts_recent. If this segment updates
1752 * ts_recent, the age will be reset later and ts_recent
1753 * will get a valid value. If it does not, setting
1754 * ts_recent to zero will at least satisfy the
1755 * requirement that zero be placed in the timestamp
1756 * echo reply when ts_recent isn't valid. The
1757 * age isn't reset until we get a valid ts_recent
1758 * because we don't want out-of-order segments to be
1759 * dropped when ts_recent is old.
1760 */
1761 tp->ts_recent = 0;
9de1f696
SZ
1762 } else if (tcp_paws_tolerance && tlen != 0 &&
1763 tp->t_state == TCPS_ESTABLISHED &&
1764 (thflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK&&
1765 !(tp->t_flags & (TF_NEEDSYN | TF_NEEDFIN)) &&
1766 th->th_ack == tp->snd_una &&
1767 tiwin == tp->snd_wnd &&
1768 TSTMP_GEQ(to.to_tsval + tcp_paws_tolerance, tp->ts_recent)&&
1769 (th->th_seq == tp->rcv_nxt ||
1770 (SEQ_GT(th->th_seq, tp->rcv_nxt) &&
1771 tcp_paws_canreasslast(tp, th, tlen)))) {
1772 /*
1773 * This tends to prevent valid new segments from being
1774 * dropped by the reordered segments sent by the fast
1775 * retransmission algorithm on the sending side, i.e.
1776 * the fast retransmitted segment w/ larger timestamp
1777 * arrives earlier than the previously sent new segments
1778 * w/ smaller timestamp.
1779 *
1780 * If following conditions are met, the segment is
1781 * accepted:
1782 * - The segment contains data
1783 * - The connection is established
1784 * - The header does not contain important flags
1785 * - SYN or FIN is not needed
1786 * - It does not acknowledge new data
1787 * - Receive window is not changed
1788 * - The timestamp is within "acceptable" range
1789 * - The new segment is what we are expecting or
1790 * the new segment could be merged w/ the last
1791 * pending segment on the reassemble queue
1792 */
1793 tcpstat.tcps_pawsaccept++;
1794 tcpstat.tcps_pawsdrop++;
984263bc
MD
1795 } else {
1796 tcpstat.tcps_rcvduppack++;
1797 tcpstat.tcps_rcvdupbyte += tlen;
1798 tcpstat.tcps_pawsdrop++;
1799 if (tlen)
1800 goto dropafterack;
1801 goto drop;
1802 }
1803 }
1804
1805 /*
984263bc
MD
1806 * In the SYN-RECEIVED state, validate that the packet belongs to
1807 * this connection before trimming the data to fit the receive
1808 * window. Check the sequence number versus IRS since we know
1809 * the sequence numbers haven't wrapped. This is a partial fix
1810 * for the "LAND" DoS attack.
1811 */
1812 if (tp->t_state == TCPS_SYN_RECEIVED && SEQ_LT(th->th_seq, tp->irs)) {
1813 rstreason = BANDLIM_RST_OPENPORT;
1814 goto dropwithreset;
1815 }
1816
1817 todrop = tp->rcv_nxt - th->th_seq;
1818 if (todrop > 0) {
91489f6b
JH
1819 if (TCP_DO_SACK(tp)) {
1820 /* Report duplicate segment at head of packet. */
1821 tp->reportblk.rblk_start = th->th_seq;
3a5d999b
SZ
1822 tp->reportblk.rblk_end = TCP_SACK_BLKEND(
1823 th->th_seq + tlen, thflags);
91489f6b
JH
1824 if (SEQ_GT(tp->reportblk.rblk_end, tp->rcv_nxt))
1825 tp->reportblk.rblk_end = tp->rcv_nxt;
c7e6499a
SZ
1826 tp->sack_flags |= (TSACK_F_DUPSEG | TSACK_F_SACKLEFT);
1827 tp->t_flags |= TF_ACKNOW;
91489f6b 1828 }
984263bc
MD
1829 if (thflags & TH_SYN) {
1830 thflags &= ~TH_SYN;
1831 th->th_seq++;
1832 if (th->th_urp > 1)
1833 th->th_urp--;
1834 else
1835 thflags &= ~TH_URG;
1836 todrop--;
1837 }
1838 /*
1839 * Following if statement from Stevens, vol. 2, p. 960.
1840 */
61896e3c
JH
1841 if (todrop > tlen ||
1842 (todrop == tlen && !(thflags & TH_FIN))) {
984263bc
MD
1843 /*
1844 * Any valid FIN must be to the left of the window.
1845 * At this point the FIN must be a duplicate or out
1846 * of sequence; drop it.
1847 */
1848 thflags &= ~TH_FIN;
1849
1850 /*
1851 * Send an ACK to resynchronize and drop any data.
1852 * But keep on processing for RST or ACK.
1853 */
1854 tp->t_flags |= TF_ACKNOW;
1855 todrop = tlen;
1856 tcpstat.tcps_rcvduppack++;
1857 tcpstat.tcps_rcvdupbyte += todrop;
1858 } else {
1859 tcpstat.tcps_rcvpartduppack++;
1860 tcpstat.tcps_rcvpartdupbyte += todrop;
1861 }
1862 drop_hdrlen += todrop; /* drop from the top afterwards */
1863 th->th_seq += todrop;
1864 tlen -= todrop;
1865 if (th->th_urp > todrop)
1866 th->th_urp -= todrop;
1867 else {
1868 thflags &= ~TH_URG;
1869 th->th_urp = 0;
1870 }
1871 }
1872
1873 /*
1874 * If new data are received on a connection after the
1875 * user processes are gone, then RST the other end.
1876 */
1877 if ((so->so_state & SS_NOFDREF) &&
1878 tp->t_state > TCPS_CLOSE_WAIT && tlen) {
1879 tp = tcp_close(tp);
1880 tcpstat.tcps_rcvafterclose++;
1881 rstreason = BANDLIM_UNLIMITED;
1882 goto dropwithreset;
1883 }
1884
1885 /*
1886 * If segment ends after window, drop trailing data
1887 * (and PUSH and FIN); if nothing left, just ACK.
1888 */
61896e3c 1889 todrop = (th->th_seq + tlen) - (tp->rcv_nxt + tp->rcv_wnd);
984263bc
MD
1890 if (todrop > 0) {
1891 tcpstat.tcps_rcvpackafterwin++;
1892 if (todrop >= tlen) {
1893 tcpstat.tcps_rcvbyteafterwin += tlen;
1894 /*
1895 * If a new connection request is received
1896 * while in TIME_WAIT, drop the old connection
1897 * and start over if the sequence numbers
1898 * are above the previous ones.
1899 */
1900 if (thflags & TH_SYN &&
1901 tp->t_state == TCPS_TIME_WAIT &&
1902 SEQ_GT(th->th_seq, tp->rcv_nxt)) {
1903 tp = tcp_close(tp);
1904 goto findpcb;
1905 }
1906 /*
1907 * If window is closed can only take segments at
1908 * window edge, and have to drop data and PUSH from
1909 * incoming segments. Continue processing, but
1910 * remember to ack. Otherwise, drop segment
1911 * and ack.
1912 */
1913 if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) {
1914 tp->t_flags |= TF_ACKNOW;
1915 tcpstat.tcps_rcvwinprobe++;
1916 } else
1917 goto dropafterack;
1918 } else
1919 tcpstat.tcps_rcvbyteafterwin += todrop;
1920 m_adj(m, -todrop);
1921 tlen -= todrop;
61896e3c 1922 thflags &= ~(TH_PUSH | TH_FIN);
984263bc
MD
1923 }
1924
1925 /*
1926 * If last ACK falls within this segment's sequence numbers,
1927 * record its timestamp.
ad0af98b
ND
1928 * NOTE:
1929 * 1) That the test incorporates suggestions from the latest
1930 * proposal of the tcplw@cray.com list (Braden 1993/04/26).
1931 * 2) That updating only on newer timestamps interferes with
1932 * our earlier PAWS tests, so this check should be solely
1933 * predicated on the sequence space of this segment.
1934 * 3) That we modify the segment boundary check to be
1935 * Last.ACK.Sent <= SEG.SEQ + SEG.LEN
1936 * instead of RFC1323's
1937 * Last.ACK.Sent < SEG.SEQ + SEG.LEN,
1938 * This modified check allows us to overcome RFC1323's
1939 * limitations as described in Stevens TCP/IP Illustrated
1940 * Vol. 2 p.869. In such cases, we can still calculate the
1941 * RTT correctly when RCV.NXT == Last.ACK.Sent.
984263bc 1942 */
ad0af98b
ND
1943 if ((to.to_flags & TOF_TS) && SEQ_LEQ(th->th_seq, tp->last_ack_sent) &&
1944 SEQ_LEQ(tp->last_ack_sent, (th->th_seq + tlen
1945 + ((thflags & TH_SYN) != 0)
1946 + ((thflags & TH_FIN) != 0)))) {
984263bc
MD
1947 tp->ts_recent_age = ticks;
1948 tp->ts_recent = to.to_tsval;
1949 }
1950
1951 /*
1952 * If a SYN is in the window, then this is an
1953 * error and we send an RST and drop the connection.
1954 */
1955 if (thflags & TH_SYN) {
1956 tp = tcp_drop(tp, ECONNRESET);
1957 rstreason = BANDLIM_UNLIMITED;
1958 goto dropwithreset;
1959 }
1960
1961 /*
1962 * If the ACK bit is off: if in SYN-RECEIVED state or SENDSYN
1963 * flag is on (half-synchronized state), then queue data for
1964 * later processing; else drop segment and return.
1965 */
61896e3c 1966 if (!(thflags & TH_ACK)) {
984263bc
MD
1967 if (tp->t_state == TCPS_SYN_RECEIVED ||
1968 (tp->t_flags & TF_NEEDSYN))
1969 goto step6;
1970 else
1971 goto drop;
1972 }
1973
1974 /*
1975 * Ack processing.
1976 */
1977 switch (tp->t_state) {
984263bc 1978 /*
91489f6b 1979 * In SYN_RECEIVED state, the ACK acknowledges our SYN, so enter
984263bc
MD
1980 * ESTABLISHED state and continue processing.
1981 * The ACK was checked above.
1982 */
1983 case TCPS_SYN_RECEIVED:
1984
1985 tcpstat.tcps_connects++;
1986 soisconnected(so);
1987 /* Do window scaling? */
61896e3c 1988 if ((tp->t_flags & (TF_RCVD_SCALE | TF_REQ_SCALE)) ==
df1d2774 1989 (TF_RCVD_SCALE | TF_REQ_SCALE))
984263bc 1990 tp->rcv_scale = tp->request_r_scale;
984263bc 1991 /*
984263bc
MD
1992 * Make transitions:
1993 * SYN-RECEIVED -> ESTABLISHED
1994 * SYN-RECEIVED* -> FIN-WAIT-1
1995 */
1996 tp->t_starttime = ticks;
1997 if (tp->t_flags & TF_NEEDFIN) {
1998 tp->t_state = TCPS_FIN_WAIT_1;
1999 tp->t_flags &= ~TF_NEEDFIN;
2000 } else {
8651f7f8 2001 tcp_established(tp);
984263bc
MD
2002 }
2003 /*
2004 * If segment contains data or ACK, will call tcp_reass()
2005 * later; if not, do so now to pass queued data to user.
2006 */
61896e3c 2007 if (tlen == 0 && !(thflags & TH_FIN))
f23061d4 2008 tcp_reass(tp, NULL, NULL, NULL);
984263bc
MD
2009 /* fall into ... */
2010
2011 /*
2012 * In ESTABLISHED state: drop duplicate ACKs; ACK out of range
2013 * ACKs. If the ack is in the range
2014 * tp->snd_una < th->th_ack <= tp->snd_max
2015 * then advance tp->snd_una to th->th_ack and drop
2016 * data from the retransmission queue. If this ACK reflects
2017 * more up to date window information we update our window information.
2018 */
2019 case TCPS_ESTABLISHED:
2020 case TCPS_FIN_WAIT_1:
2021 case TCPS_FIN_WAIT_2:
2022 case TCPS_CLOSE_WAIT:
2023 case TCPS_CLOSING:
2024 case TCPS_LAST_ACK:
2025 case TCPS_TIME_WAIT:
2026
2027 if (SEQ_LEQ(th->th_ack, tp->snd_una)) {
942d88ef
SZ
2028 boolean_t maynotdup = FALSE;
2029
91489f6b
JH
2030 if (TCP_DO_SACK(tp))
2031 tcp_sack_update_scoreboard(tp, &to);
942d88ef
SZ
2032
2033 if (tlen != 0 || tiwin != tp->snd_wnd ||
2034 ((thflags & TH_FIN) && !(tp->t_flags & TF_SAWFIN)))
2035 maynotdup = TRUE;
2036
a48c5dd5 2037 if (!tcp_callout_active(tp, tp->tt_rexmt) ||
91489f6b 2038 th->th_ack != tp->snd_una) {
942d88ef 2039 if (!maynotdup)
52f9ffcf 2040 tcpstat.tcps_rcvdupack++;
91489f6b
JH
2041 tp->t_dupacks = 0;
2042 break;
2043 }
942d88ef
SZ
2044
2045#define DELAY_DUPACK \
2046do { \
2047 delayed_dupack = TRUE; \
2048 th_dupack = th->th_ack; \
2049 to_flags = to.to_flags; \
2050} while (0)
2051 if (maynotdup) {
859bc3f7 2052 if (!tcp_do_rfc6675 ||
ffe35e17
SZ
2053 !TCP_DO_SACK(tp) ||
2054 (to.to_flags &
2055 (TOF_SACK | TOF_SACK_REDUNDANT))
2056 != TOF_SACK) {
2057 tp->t_dupacks = 0;
91489f6b 2058 } else {
942d88ef 2059 DELAY_DUPACK;
91489f6b 2060 }
95b22adf 2061 break;
95b22adf 2062 }
942d88ef
SZ
2063 if ((thflags & TH_FIN) && !(tp->t_flags & TF_QUEDFIN)) {
2064 /*
2065 * This could happen, if the reassemable
2066 * queue overflew or was drained. Don't
2067 * drop this FIN here; defer the duplicated
2068 * ACK processing until this FIN gets queued.
2069 */
2070 DELAY_DUPACK;
2071 break;
2072 }
2073#undef DELAY_DUPACK
2074
0a832381 2075 if (tcp_recv_dupack(tp, th->th_ack, to.to_flags))
ffe35e17 2076 goto drop;
27f4bf33
SZ
2077 else
2078 break;
984263bc
MD
2079 }
2080
2081 KASSERT(SEQ_GT(th->th_ack, tp->snd_una), ("th_ack <= snd_una"));
984263bc
MD
2082 tp->t_dupacks = 0;
2083 if (SEQ_GT(th->th_ack, tp->snd_max)) {
5a274421
JH
2084 /*
2085 * Detected optimistic ACK attack.
2086 * Force slow-start to de-synchronize attack.
2087 */
2088 tp->snd_cwnd = tp->t_maxseg;
8acdb67c 2089 tp->snd_wacked = 0;
5a274421 2090
984263bc
MD
2091 tcpstat.tcps_rcvacktoomuch++;
2092 goto dropafterack;
2093 }
2094 /*
2095 * If we reach this point, ACK is not a duplicate,
2096 * i.e., it ACKs something we sent.
2097 */
2098 if (tp->t_flags & TF_NEEDSYN) {
2099 /*
2100 * T/TCP: Connection was half-synchronized, and our
2101 * SYN has been ACK'd (so connection is now fully
2102 * synchronized). Go to non-starred state,
2103 * increment snd_una for ACK of SYN, and check if
2104 * we can do window scaling.
2105 */
2106 tp->t_flags &= ~TF_NEEDSYN;
2107 tp->snd_una++;
2108 /* Do window scaling? */
61896e3c 2109 if ((tp->t_flags & (TF_RCVD_SCALE | TF_REQ_SCALE)) ==
df1d2774 2110 (TF_RCVD_SCALE | TF_REQ_SCALE))
984263bc 2111 tp->rcv_scale = tp->request_r_scale;
984263bc
MD
2112 }
2113
2114process_ACK:
2115 acked = th->th_ack - tp->snd_una;
2116 tcpstat.tcps_rcvackpack++;
2117 tcpstat.tcps_rcvackbyte += acked;
2118
b5572302 2119 if (tcp_do_eifel_detect && acked > 0 &&
95b22adf 2120 (to.to_flags & TOF_TS) && (to.to_tsecr != 0) &&
1c8b7a61 2121 (tp->rxt_flags & TRXT_F_FIRSTACCACK)) {
bfdb979e
JH
2122 /* Eifel detection applicable. */
2123 if (to.to_tsecr < tp->t_rexmtTS) {
bfdb979e 2124 ++tcpstat.tcps_eifeldetected;
8819433a 2125 tcp_revert_congestion_state(tp);
928c3291 2126 if (tp->t_rxtshift != 1 ||
8819433a
JH
2127 ticks >= tp->t_badrxtwin)
2128 ++tcpstat.tcps_rttcantdetect;
bfdb979e
JH
2129 }
2130 } else if (tp->t_rxtshift == 1 && ticks < tp->t_badrxtwin) {
b5572302
JH
2131 /*
2132 * If we just performed our first retransmit,
2133 * and the ACK arrives within our recovery window,
2134 * then it was a mistake to do the retransmit
91489f6b 2135 * in the first place. Recover our original cwnd
b5572302
JH
2136 * and ssthresh, and proceed to transmit where we
2137 * left off.
2138 */
bfdb979e
JH
2139 tcp_revert_congestion_state(tp);
2140 ++tcpstat.tcps_rttdetected;
984263bc
MD
2141 }
2142
2143 /*
2144 * If we have a timestamp reply, update smoothed
2145 * round trip time. If no timestamp is present but
2146 * transmit timer is running and timed sequence
2147 * number was acked, update smoothed round trip time.
2148 * Since we now have an rtt measurement, cancel the
2149 * timer backoff (cf., Phil Karn's retransmit alg.).
2150 * Recompute the initial retransmit timer.
2151 *
2152 * Some machines (certain windows boxes) send broken
d24ce1dc 2153 * timestamp replies during the SYN+ACK phase, ignore
984263bc
MD
2154 * timestamps of 0.
2155 */
95b22adf 2156 if ((to.to_flags & TOF_TS) && (to.to_tsecr != 0))
073ec6c4 2157 tcp_xmit_timer(tp, ticks - to.to_tsecr + 1, th->th_ack);
95b22adf 2158 else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq))
073ec6c4 2159 tcp_xmit_timer(tp, ticks - tp->t_rtttime, th->th_ack);
984263bc
MD
2160 tcp_xmit_bandwidth_limit(tp, th->th_ack);
2161
2162 /*
984263bc
MD
2163 * If no data (only SYN) was ACK'd,
2164 * skip rest of ACK processing.
2165 */
2166 if (acked == 0)
2167 goto step6;
2168
efd4b327 2169 /* Stop looking for an acceptable ACK since one was received. */
1c8b7a61
SZ
2170 tp->rxt_flags &= ~(TRXT_F_FIRSTACCACK |
2171 TRXT_F_FASTREXMT | TRXT_F_EARLYREXMT);
efd4b327 2172
6d49aa6f
MD
2173 if (acked > so->so_snd.ssb_cc) {
2174 tp->snd_wnd -= so->so_snd.ssb_cc;
2175 sbdrop(&so->so_snd.sb, (int)so->so_snd.ssb_cc);
61896e3c 2176 ourfinisacked = TRUE;
984263bc 2177 } else {
6d49aa6f 2178 sbdrop(&so->so_snd.sb, acked);
984263bc 2179 tp->snd_wnd -= acked;
61896e3c 2180 ourfinisacked = FALSE;
984263bc
MD
2181 }
2182 sowwakeup(so);
91489f6b
JH
2183
2184 /*
2185 * Update window information.
91489f6b 2186 */
e126661b 2187 if (acceptable_window_update(tp, th, tiwin)) {
91489f6b
JH
2188 /* keep track of pure window updates */
2189 if (tlen == 0 && tp->snd_wl2 == th->th_ack &&
2190 tiwin > tp->snd_wnd)
2191 tcpstat.tcps_rcvwinupd++;
2192 tp->snd_wnd = tiwin;
2193 tp->snd_wl1 = th->th_seq;
2194 tp->snd_wl2 = th->th_ack;
2195 if (tp->snd_wnd > tp->max_sndwnd)
2196 tp->max_sndwnd = tp->snd_wnd;
2197 needoutput = TRUE;
2198 }
2199
2200 tp->snd_una = th->th_ack;
2201 if (TCP_DO_SACK(tp))
2202 tcp_sack_update_scoreboard(tp, &to);
95b22adf 2203 if (IN_FASTRECOVERY(tp)) {
91489f6b 2204 if (SEQ_GEQ(th->th_ack, tp->snd_recover)) {
95b22adf 2205 EXIT_FASTRECOVERY(tp);
91489f6b
JH
2206 needoutput = TRUE;
2207 /*
2208 * If the congestion window was inflated
2209 * to account for the other side's
2210 * cached packets, retract it.
8acdb67c
JH
2211 */
2212 if (!TCP_DO_SACK(tp))
2213 tp->snd_cwnd = tp->snd_ssthresh;
2214
2215 /*
91489f6b
JH
2216 * Window inflation should have left us
2217 * with approximately snd_ssthresh outstanding
2218 * data. But, in case we would be inclined
2219 * to send a burst, better do it using
2220 * slow start.
2221 */
91489f6b
JH
2222 if (SEQ_GT(th->th_ack + tp->snd_cwnd,
2223 tp->snd_max + 2 * tp->t_maxseg))
2224 tp->snd_cwnd =
2225 (tp->snd_max - tp->snd_una) +
2226 2 * tp->t_maxseg;
8acdb67c
JH
2227
2228 tp->snd_wacked = 0;
91489f6b
JH
2229 } else {
2230 if (TCP_DO_SACK(tp)) {
2231 tp->snd_max_rexmt = tp->snd_max;
ccb518ea
SZ
2232 tcp_sack_rexmt(tp,
2233 tp->snd_una == tp->rexmt_high);
91489f6b
JH
2234 } else {
2235 tcp_newreno_partial_ack(tp, th, acked);
2236 }
2237 needoutput = FALSE;
2238 }
95b22adf 2239 } else {
91489f6b 2240 /*
8acdb67c
JH
2241 * Open the congestion window. When in slow-start,
2242 * open exponentially: maxseg per packet. Otherwise,
2243 * open linearly: maxseg per window.
91489f6b 2244 */
8acdb67c
JH
2245 if (tp->snd_cwnd <= tp->snd_ssthresh) {
2246 u_int abc_sslimit =
2247 (SEQ_LT(tp->snd_nxt, tp->snd_max) ?
2248 tp->t_maxseg : 2 * tp->t_maxseg);
2249
2250 /* slow-start */
2251 tp->snd_cwnd += tcp_do_abc ?
2252 min(acked, abc_sslimit) : tp->t_maxseg;
2253 } else {
2254 /* linear increase */
2255 tp->snd_wacked += tcp_do_abc ? acked :
2256 tp->t_maxseg;
2257 if (tp->snd_wacked >= tp->snd_cwnd) {
2258 tp->snd_wacked -= tp->snd_cwnd;
2259 tp->snd_cwnd += tp->t_maxseg;
2260 }
2261 }
2262 tp->snd_cwnd = min(tp->snd_cwnd,
2263 TCP_MAXWIN << tp->snd_scale);
95b22adf 2264 tp->snd_recover = th->th_ack - 1;
cfb3f3f4 2265 }
984263bc
MD
2266 if (SEQ_LT(tp->snd_nxt, tp->snd_una))
2267 tp->snd_nxt = tp->snd_una;
2268
91489f6b
JH
2269 /*
2270 * If all outstanding data is acked, stop retransmit
2271 * timer and remember to restart (more output or persist).
2272 * If there is more data to be acked, restart retransmit
2273 * timer, using current (possibly backed-off) value.
2274 */
2275 if (th->th_ack == tp->snd_max) {
a48c5dd5 2276 tcp_callout_stop(tp, tp->tt_rexmt);
91489f6b 2277 needoutput = TRUE;
a48c5dd5
SZ
2278 } else if (!tcp_callout_active(tp, tp->tt_persist)) {
2279 tcp_callout_reset(tp, tp->tt_rexmt, tp->t_rxtcur,
2280 tcp_timer_rexmt);
2281 }
91489f6b 2282
984263bc 2283 switch (tp->t_state) {
984263bc
MD
2284 /*
2285 * In FIN_WAIT_1 STATE in addition to the processing
2286 * for the ESTABLISHED state if our FIN is now acknowledged
2287 * then enter FIN_WAIT_2.
2288 */
2289 case TCPS_FIN_WAIT_1:
2290 if (ourfinisacked) {
2291 /*
2292 * If we can't receive any more
2293 * data, then closing user can proceed.
2294 * Starting the timer is contrary to the
2295 * specification, but if we don't get a FIN
2296 * we'll hang forever.
2297 */
2298 if (so->so_state & SS_CANTRCVMORE) {
2299 soisdisconnected(so);
a48c5dd5 2300 tcp_callout_reset(tp, tp->tt_2msl,
5d61ded3 2301 tp->t_maxidle, tcp_timer_2msl);
984263bc
MD
2302 }
2303 tp->t_state = TCPS_FIN_WAIT_2;
2304 }
2305 break;
2306
95b22adf 2307 /*
984263bc
MD
2308 * In CLOSING STATE in addition to the processing for
2309 * the ESTABLISHED state if the ACK acknowledges our FIN
2310 * then enter the TIME-WAIT state, otherwise ignore
2311 * the segment.
2312 */
2313 case TCPS_CLOSING:
2314 if (ourfinisacked) {
2315 tp->t_state = TCPS_TIME_WAIT;
2316 tcp_canceltimers(tp);
27b8aee3 2317 tcp_callout_reset(tp, tp->tt_2msl,
01d3427a
SZ
2318 2 * tcp_rmx_msl(tp),
2319 tcp_timer_2msl);
984263bc
MD
2320 soisdisconnected(so);
2321 }
2322 break;
2323
2324 /*
2325 * In LAST_ACK, we may still be waiting for data to drain
2326 * and/or to be acked, as well as for the ack of our FIN.
2327 * If our FIN is now acknowledged, delete the TCB,
2328 * enter the closed state and return.
2329 */
2330 case TCPS_LAST_ACK:
2331 if (ourfinisacked) {
2332 tp = tcp_close(tp);
2333 goto drop;
2334 }
2335 break;
2336
2337 /*
2338 * In TIME_WAIT state the only thing that should arrive
2339 * is a retransmission of the remote FIN. Acknowledge
2340 * it and restart the finack timer.
2341 */
2342 case TCPS_TIME_WAIT:
01d3427a 2343 tcp_callout_reset(tp, tp->tt_2msl, 2 * tcp_rmx_msl(tp),
a48c5dd5 2344 tcp_timer_2msl);
984263bc
MD
2345 goto dropafterack;
2346 }
2347 }
2348
2349step6:
2350 /*
2351 * Update window information.
2352 * Don't look at window if no ACK: TAC's send garbage on first SYN.
2353 */
2354 if ((thflags & TH_ACK) &&
df9d7670 2355 acceptable_window_update(tp, th, tiwin)) {
984263bc 2356 /* keep track of pure window updates */
b5572302
JH
2357 if (tlen == 0 && tp->snd_wl2 == th->th_ack &&
2358 tiwin > tp->snd_wnd)
984263bc
MD
2359 tcpstat.tcps_rcvwinupd++;
2360 tp->snd_wnd = tiwin;
2361 tp->snd_wl1 = th->th_seq;
2362 tp->snd_wl2 = th->th_ack;
2363 if (tp->snd_wnd > tp->max_sndwnd)
2364 tp->max_sndwnd = tp->snd_wnd;
61896e3c 2365 needoutput = TRUE;
984263bc
MD
2366 }
2367
2368 /*
2369 * Process segments with URG.
2370 */
2371 if ((thflags & TH_URG) && th->th_urp &&
95b22adf 2372 !TCPS_HAVERCVDFIN(tp->t_state)) {
984263bc
MD
2373 /*
2374 * This is a kludge, but if we receive and accept
2375 * random urgent pointers, we'll crash in
2376 * soreceive. It's hard to imagine someone
2377 * actually wanting to send this much urgent data.
2378 */
6d49aa6f 2379 if (th->th_urp + so->so_rcv.ssb_cc > sb_max) {
984263bc
MD
2380 th->th_urp = 0; /* XXX */
2381 thflags &= ~TH_URG; /* XXX */
2382 goto dodata; /* XXX */
2383 }
2384 /*
2385 * If this segment advances the known urgent pointer,
2386 * then mark the data stream. This should not happen
2387 * in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since
2388 * a FIN has been received from the remote side.
2389 * In these states we ignore the URG.
2390 *
2391 * According to RFC961 (Assigned Protocols),
2392 * the urgent pointer points to the last octet
2393 * of urgent data. We continue, however,
2394 * to consider it to indicate the first octet
2395 * of data past the urgent section as the original
2396 * spec states (in one of two places).
2397 */
61896e3c 2398 if (SEQ_GT(th->th_seq + th->th_urp, tp->rcv_up)) {
984263bc 2399 tp->rcv_up = th->th_seq + th->th_urp;
6d49aa6f 2400 so->so_oobmark = so->so_rcv.ssb_cc +
984263bc
MD
2401 (tp->rcv_up - tp->rcv_nxt) - 1;
2402 if (so->so_oobmark == 0)
6cef7136 2403 sosetstate(so, SS_RCVATMARK);
984263bc
MD
2404 sohasoutofband(so);
2405 tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA);
2406 }
2407 /*
2408 * Remove out of band data so doesn't get presented to user.
2409 * This can happen independent of advancing the URG pointer,
2410 * but if two URG's are pending at once, some out-of-band
2411 * data may creep in... ick.
2412 */
61896e3c
JH
2413 if (th->th_urp <= (u_long)tlen &&
2414 !(so->so_options & SO_OOBINLINE)) {
2415 /* hdr drop is delayed */
2416 tcp_pulloutofband(so, th, m, drop_hdrlen);
2417 }
984263bc
MD
2418 } else {
2419 /*
2420 * If no out of band data is expected,
2421 * pull receive urgent pointer along
2422 * with the receive window.
2423 */
2424 if (SEQ_GT(tp->rcv_nxt, tp->rcv_up))
2425 tp->rcv_up = tp->rcv_nxt;
2426 }
984263bc 2427
61896e3c 2428dodata: /* XXX */
984263bc
MD
2429 /*
2430 * Process the segment text, merging it into the TCP sequencing queue,
2431 * and arranging for acknowledgment of receipt if necessary.
2432 * This process logically involves adjusting tp->rcv_wnd as data
2433 * is presented to the user (this happens in tcp_usrreq.c,
2434 * case PRU_RCVD). If a FIN has already been received on this
2435 * connection then we just ignore the text.
2436 */
95b22adf 2437 if ((tlen || (thflags & TH_FIN)) && !TCPS_HAVERCVDFIN(tp->t_state)) {
942d88ef
SZ
2438 if (thflags & TH_FIN)
2439 tp->t_flags |= TF_SAWFIN;
984263bc
MD
2440 m_adj(m, drop_hdrlen); /* delayed header drop */
2441 /*
2442 * Insert segment which includes th into TCP reassembly queue
2443 * with control block tp. Set thflags to whether reassembly now
2444 * includes a segment with FIN. This handles the common case
2445 * inline (segment is the next to be received on an established
2446 * connection, and the queue is empty), avoiding linkage into
2447 * and removal from the queue and repetition of various
2448 * conversions.
2449 * Set DELACK for segments received in order, but ack
2450 * immediately when segments are out of order (so
2451 * fast retransmit can work).
2452 */
2453 if (th->th_seq == tp->rcv_nxt &&
0f9e45de 2454 TAILQ_EMPTY(&tp->t_segq) &&
984263bc 2455 TCPS_HAVEESTABLISHED(tp->t_state)) {
942d88ef
SZ
2456 if (thflags & TH_FIN)
2457 tp->t_flags |= TF_QUEDFIN;
a48c5dd5
SZ
2458 if (DELAY_ACK(tp)) {
2459 tcp_callout_reset(tp, tp->tt_delack,
2460 tcp_delacktime, tcp_timer_delack);
2461 } else {
984263bc 2462 tp->t_flags |= TF_ACKNOW;
a48c5dd5 2463 }
984263bc
MD
2464 tp->rcv_nxt += tlen;
2465 thflags = th->th_flags & TH_FIN;
2466 tcpstat.tcps_rcvpack++;
2467 tcpstat.tcps_rcvbyte += tlen;
2468 ND6_HINT(tp);
6cef7136 2469 if (so->so_state & SS_CANTRCVMORE) {
984263bc 2470 m_freem(m);
6cef7136
MD
2471 } else {
2472 lwkt_gettoken(&so->so_rcv.ssb_token);
6d49aa6f 2473 ssb_appendstream(&so->so_rcv, m);
6cef7136
MD
2474 lwkt_reltoken(&so->so_rcv.ssb_token);
2475 }
984263bc
MD
2476 sorwakeup(so);
2477 } else {
c7e6499a 2478 if (!(tp->sack_flags & TSACK_F_DUPSEG)) {
91489f6b
JH
2479 /* Initialize SACK report block. */
2480 tp->reportblk.rblk_start = th->th_seq;
3a5d999b
SZ
2481 tp->reportblk.rblk_end = TCP_SACK_BLKEND(
2482 th->th_seq + tlen, thflags);
91489f6b 2483 }
984263bc
MD
2484 thflags = tcp_reass(tp, th, &tlen, m);
2485 tp->t_flags |= TF_ACKNOW;
2486 }
2487
2488 /*
2489 * Note the amount of data that peer has sent into
2490 * our window, in order to estimate the sender's
2491 * buffer size.
2492 */
6d49aa6f 2493 len = so->so_rcv.ssb_hiwat - (tp->rcv_adv - tp->rcv_nxt);
984263bc
MD
2494 } else {
2495 m_freem(m);
2496 thflags &= ~TH_FIN;
2497 }
2498
2499 /*
2500 * If FIN is received ACK the FIN and let the user know
2501 * that the connection is closing.
2502 */
2503 if (thflags & TH_FIN) {
95b22adf 2504 if (!TCPS_HAVERCVDFIN(tp->t_state)) {
984263bc
MD
2505 socantrcvmore(so);
2506 /*
2507 * If connection is half-synchronized
2508 * (ie NEEDSYN flag on) then delay ACK,
2509 * so it may be piggybacked when SYN is sent.
2510 * Otherwise, since we received a FIN then no
2511 * more input can be expected, send ACK now.
2512 */
a48c5dd5
SZ
2513 if (DELAY_ACK(tp) && (tp->t_flags & TF_NEEDSYN)) {
2514 tcp_callout_reset(tp, tp->tt_delack,
2515 tcp_delacktime, tcp_timer_delack);
2516 } else {
984263bc 2517 tp->t_flags |= TF_ACKNOW;
a48c5dd5 2518 }
984263bc
MD
2519 tp->rcv_nxt++;
2520 }
984263bc 2521
61896e3c 2522 switch (tp->t_state) {
95b22adf 2523 /*
984263bc
MD
2524 * In SYN_RECEIVED and ESTABLISHED STATES
2525 * enter the CLOSE_WAIT state.
2526 */
2527 case TCPS_SYN_RECEIVED:
2528 tp->t_starttime = ticks;
2529 /*FALLTHROUGH*/
2530 case TCPS_ESTABLISHED:
2531 tp->t_state = TCPS_CLOSE_WAIT;
2532 break;
2533
95b22adf 2534 /*
984263bc
MD
2535 * If still in FIN_WAIT_1 STATE FIN has not been acked so
2536 * enter the CLOSING state.
2537 */
2538 case TCPS_FIN_WAIT_1:
2539 tp->t_state = TCPS_CLOSING;
2540 break;
2541
95b22adf 2542 /*
984263bc
MD
2543 * In FIN_WAIT_2 state enter the TIME_WAIT state,
2544 * starting the time-wait timer, turning off the other
2545 * standard timers.
2546 */
2547 case TCPS_FIN_WAIT_2:
2548 tp->t_state = TCPS_TIME_WAIT;
2549 tcp_canceltimers(tp);
01d3427a 2550 tcp_callout_reset(tp, tp->tt_2msl, 2 * tcp_rmx_msl(tp),
a48c5dd5 2551 tcp_timer_2msl);
984263bc
MD
2552 soisdisconnected(so);
2553 break;
2554
2555 /*
2556 * In TIME_WAIT state restart the 2 MSL time_wait timer.
2557 */
2558 case TCPS_TIME_WAIT:
01d3427a 2559 tcp_callout_reset(tp, tp->tt_2msl, 2 * tcp_rmx_msl(tp),
a48c5dd5 2560 tcp_timer_2msl);
984263bc
MD
2561 break;
2562 }
2563 }
61896e3c 2564
984263bc
MD
2565#ifdef TCPDEBUG
2566 if (so->so_options & SO_DEBUG)
f23061d4 2567 tcp_trace(TA_INPUT, ostate, tp, tcp_saveipgen, &tcp_savetcp, 0);
984263bc
MD
2568#endif
2569
2570 /*
27f4bf33
SZ
2571 * Delayed duplicated ACK processing
2572 */
0a832381 2573 if (delayed_dupack && tcp_recv_dupack(tp, th_dupack, to_flags))
27f4bf33
SZ
2574 needoutput = FALSE;
2575
2576 /*
984263bc
MD
2577 * Return any desired output.
2578 */
2fb3a851
SZ
2579 if ((tp->t_flags & TF_ACKNOW) ||
2580 (needoutput && tcp_sack_report_needed(tp))) {
2581 tcp_output_cancel(tp);
2582 tcp_output_fair(tp);
2583 } else if (needoutput && !tcp_output_pending(tp)) {
2584 tcp_output_fair(tp);
2585 }
d58ca578 2586 tcp_sack_report_cleanup(tp);
002c1265 2587 return(IPPROTO_DONE);
984263bc
MD
2588
2589dropafterack:
2590 /*
2591 * Generate an ACK dropping incoming segment if it occupies
2592 * sequence space, where the ACK reflects our state.
2593 *
2594 * We can now skip the test for the RST flag since all
2595 * paths to this code happen after packets containing
2596 * RST have been dropped.
2597 *
2598 * In the SYN-RECEIVED state, don't send an ACK unless the
2599 * segment we received passes the SYN-RECEIVED ACK test.
2600 * If it fails send a RST. This breaks the loop in the
2601 * "LAND" DoS attack, and also prevents an ACK storm
2602 * between two listening ports that have been sent forged
2603 * SYN segments, each with the source address of the other.
2604 */
2605 if (tp->t_state == TCPS_SYN_RECEIVED && (thflags & TH_ACK) &&
2606 (SEQ_GT(tp->snd_una, th->th_ack) ||
2607 SEQ_GT(th->th_ack, tp->snd_max)) ) {
2608 rstreason = BANDLIM_RST_OPENPORT;
2609 goto dropwithreset;
2610 }
2611#ifdef TCPDEBUG
2612 if (so->so_options & SO_DEBUG)
f23061d4 2613 tcp_trace(TA_DROP, ostate, tp, tcp_saveipgen, &tcp_savetcp, 0);
984263bc
MD
2614#endif
2615 m_freem(m);
2616 tp->t_flags |= TF_ACKNOW;
f23061d4 2617 tcp_output(tp);
d58ca578 2618 tcp_sack_report_cleanup(tp);
002c1265 2619 return(IPPROTO_DONE);
984263bc
MD
2620
2621dropwithreset:
2622 /*
2623 * Generate a RST, dropping incoming segment.
2624 * Make ACK acceptable to originator of segment.
2625 * Don't bother to respond if destination was broadcast/multicast.
2626 */
61896e3c 2627 if ((thflags & TH_RST) || m->m_flags & (M_BCAST | M_MCAST))
984263bc
MD
2628 goto drop;
2629 if (isipv6) {
2630 if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
2631 IN6_IS_ADDR_MULTICAST(&ip6->ip6_src))
2632 goto drop;
2633 } else {
2634 if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) ||
2635 IN_MULTICAST(ntohl(ip->ip_src.s_addr)) ||
95b22adf
JH
2636 ip->ip_src.s_addr == htonl(INADDR_BROADCAST) ||
2637 in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif))
984263bc
MD
2638 goto drop;
2639 }
2640 /* IPv6 anycast check is done at tcp6_input() */
2641
2642 /*
2643 * Perform bandwidth limiting.
2644 */
2645#ifdef ICMP_BANDLIM
2646 if (badport_bandlim(rstreason) < 0)
2647 goto drop;
2648#endif
2649
2650#ifdef TCPDEBUG
2651 if (tp == NULL || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
f23061d4 2652 tcp_trace(TA_DROP, ostate, tp, tcp_saveipgen, &tcp_savetcp, 0);
984263bc
MD
2653#endif
2654 if (thflags & TH_ACK)
2655 /* mtod() below is safe as long as hdr dropping is delayed */
2656 tcp_respond(tp, mtod(m, void *), th, m, (tcp_seq)0, th->th_ack,
2657 TH_RST);
2658 else {
2659 if (thflags & TH_SYN)
2660 tlen++;
2661 /* mtod() below is safe as long as hdr dropping is delayed */
61896e3c
JH
2662 tcp_respond(tp, mtod(m, void *), th, m, th->th_seq + tlen,
2663 (tcp_seq)0, TH_RST | TH_ACK);
984263bc 2664 }
d58ca578
SZ
2665 if (tp != NULL)
2666 tcp_sack_report_cleanup(tp);
002c1265 2667 return(IPPROTO_DONE);
984263bc
MD
2668
2669drop:
2670 /*
2671 * Drop space held by incoming segment and return.
2672 */
2673#ifdef TCPDEBUG
2674 if (tp == NULL || (tp->t_inpcb->inp_socket->so_options & SO_DEBUG))
f23061d4 2675 tcp_trace(TA_DROP, ostate, tp, tcp_saveipgen, &tcp_savetcp, 0);
984263bc
MD
2676#endif
2677 m_freem(m);
d58ca578
SZ
2678 if (tp != NULL)
2679 tcp_sack_report_cleanup(tp);
002c1265 2680 return(IPPROTO_DONE);
984263bc
MD
2681}
2682
2683/*
2684 * Parse TCP options and place in tcpopt.
2685 */
2686static void
6c1bbf57
SZ
2687tcp_dooptions(struct tcpopt *to, u_char *cp, int cnt, boolean_t is_syn,
2688 tcp_seq ack)
984263bc 2689{
91489f6b 2690 int opt, optlen, i;
984263bc
MD
2691
2692 to->to_flags = 0;
2693 for (; cnt > 0; cnt -= optlen, cp += optlen) {
2694 opt = cp[0];
2695 if (opt == TCPOPT_EOL)
2696 break;
2697 if (opt == TCPOPT_NOP)
2698 optlen = 1;
2699 else {
2700 if (cnt < 2)
2701 break;
2702 optlen = cp[1];
2703 if (optlen < 2 || optlen > cnt)
2704 break;
2705 }
2706 switch (opt) {
2707 case TCPOPT_MAXSEG:
2708 if (optlen != TCPOLEN_MAXSEG)
2709 continue;
2710 if (!is_syn)
2711 continue;
2712 to->to_flags |= TOF_MSS;
407e896e 2713 bcopy(cp + 2, &to->to_mss, sizeof to->to_mss);
984263bc
MD
2714 to->to_mss = ntohs(to->to_mss);
2715 break;
2716 case TCPOPT_WINDOW:
2717 if (optlen != TCPOLEN_WINDOW)
2718 continue;
95b22adf 2719 if (!is_syn)
984263bc
MD
2720 continue;
2721 to->to_flags |= TOF_SCALE;
2722 to->to_requested_s_scale = min(cp[2], TCP_MAX_WINSHIFT);
2723 break;
2724 case TCPOPT_TIMESTAMP:
2725 if (optlen != TCPOLEN_TIMESTAMP)
2726 continue;
2727 to->to_flags |= TOF_TS;
407e896e 2728 bcopy(cp + 2, &to->to_tsval, sizeof to->to_tsval);
984263bc 2729 to->to_tsval = ntohl(to->to_tsval);
407e896e 2730 bcopy(cp + 6, &to->to_tsecr, sizeof to->to_tsecr);
984263bc 2731 to->to_tsecr = ntohl(to->to_tsecr);
ad0af98b
ND
2732 /*
2733 * If echoed timestamp is later than the current time,
2734 * fall back to non RFC1323 RTT calculation.
2735 */
2736 if (to->to_tsecr != 0 && TSTMP_GT(to->to_tsecr, ticks))
2737 to->to_tsecr = 0;
984263bc 2738 break;
91489f6b
JH
2739 case TCPOPT_SACK_PERMITTED:
2740 if (optlen != TCPOLEN_SACK_PERMITTED)
2741 continue;
2742 if (!is_syn)
2743 continue;
2744 to->to_flags |= TOF_SACK_PERMITTED;
2745 break;
2746 case TCPOPT_SACK:
2747 if ((optlen - 2) & 0x07) /* not multiple of 8 */
2748 continue;
2749 to->to_nsackblocks = (optlen - 2) / 8;
2750 to->to_sackblocks = (struct raw_sackblock *) (cp + 2);
2751 to->to_flags |= TOF_SACK;
2752 for (i = 0; i < to->to_nsackblocks; i++) {
2753 struct raw_sackblock *r = &to->to_sackblocks[i];
2754
2755 r->rblk_start = ntohl(r->rblk_start);
2756 r->rblk_end = ntohl(r->rblk_end);
865b0477
SZ
2757
2758 if (SEQ_LEQ(r->rblk_end, r->rblk_start)) {
2759 /*
2760 * Invalid SACK block; discard all
2761 * SACK blocks
2762 */
02cc2f35 2763 tcpstat.tcps_rcvbadsackopt++;
865b0477
SZ
2764 to->to_nsackblocks = 0;
2765 to->to_sackblocks = NULL;
2766 to->to_flags &= ~TOF_SACK;
2767 break;
2768 }
91489f6b 2769 }
6c1bbf57
SZ
2770 if ((to->to_flags & TOF_SACK) &&
2771 tcp_sack_ndsack_blocks(to->to_sackblocks,
2772 to->to_nsackblocks, ack))
2773 to->to_flags |= TOF_DSACK;
91489f6b 2774 break;
b1992928
MD
2775#ifdef TCP_SIGNATURE
2776 /*
2777 * XXX In order to reply to a host which has set the
2778 * TCP_SIGNATURE option in its initial SYN, we have to
2779 * record the fact that the option was observed here
2780 * for the syncache code to perform the correct response.
2781 */
2782 case TCPOPT_SIGNATURE:
2783 if (optlen != TCPOLEN_SIGNATURE)
2784 continue;
2785 to->to_flags |= (TOF_SIGNATURE | TOF_SIGLEN);
2786 break;
2787#endif /* TCP_SIGNATURE */
984263bc
MD
2788 default:
2789 continue;
2790 }
2791 }
2792}
2793
2794/*
2795 * Pull out of band byte out of a segment so
2796 * it doesn't appear in the user's data queue.
2797 * It is still reflected in the segment length for
2798 * sequencing purposes.
95b22adf 2799 * "off" is the delayed to be dropped hdrlen.
984263bc
MD
2800 */
2801static void
95b22adf 2802tcp_pulloutofband(struct socket *so, struct tcphdr *th, struct mbuf *m, int off)
984263bc
MD
2803{
2804 int cnt = off + th->th_urp - 1;
2805
2806 while (cnt >= 0) {
2807 if (m->m_len > cnt) {
2808 char *cp = mtod(m, caddr_t) + cnt;
2809 struct tcpcb *tp = sototcpcb(so);
2810
2811 tp->t_iobc = *cp;
2812 tp->t_oobflags |= TCPOOB_HAVEDATA;
95b22adf 2813 bcopy(cp + 1, cp, m->m_len - cnt - 1);
984263bc
MD
2814 m->m_len--;
2815 if (m->m_flags & M_PKTHDR)
2816 m->m_pkthdr.len--;
2817 return;
2818 }
2819 cnt -= m->m_len;
2820 m = m->m_next;
4090d6ff 2821 if (m == NULL)
984263bc
MD
2822 break;
2823 }
2824 panic("tcp_pulloutofband");
2825}
2826
2827/*
2828 * Collect new round-trip time estimate
2829 * and update averages and current timeout.
2830 */
2831static void
073ec6c4 2832tcp_xmit_timer(struct tcpcb *tp, int rtt, tcp_seq ack)
984263bc 2833{
073ec6c4 2834 int rebaserto = 0;
984263bc
MD
2835
2836 tcpstat.tcps_rttupdated++;
2837 tp->t_rttupdated++;
1c8b7a61
SZ
2838 if ((tp->rxt_flags & TRXT_F_REBASERTO) &&
2839 SEQ_GT(ack, tp->snd_max_prev)) {
073ec6c4
SZ
2840#ifdef DEBUG_EIFEL_RESPONSE
2841 kprintf("srtt/rttvar, prev %d/%d, cur %d/%d, ",
2842 tp->t_srtt_prev, tp->t_rttvar_prev,
2843 tp->t_srtt, tp->t_rttvar);
2844#endif
2845
2846 tcpstat.tcps_eifelresponse++;
2847 rebaserto = 1;
1c8b7a61 2848 tp->rxt_flags &= ~TRXT_F_REBASERTO;
073ec6c4
SZ
2849 tp->t_srtt = max(tp->t_srtt_prev, (rtt << TCP_RTT_SHIFT));
2850 tp->t_rttvar = max(tp->t_rttvar_prev,
2851 (rtt << (TCP_RTTVAR_SHIFT - 1)));
2852 if (tp->t_rttbest > tp->t_srtt + tp->t_rttvar)
2853 tp->t_rttbest = tp->t_srtt + tp->t_rttvar;
2854
2855#ifdef DEBUG_EIFEL_RESPONSE
2856 kprintf("new %d/%d ", tp->t_srtt, tp->t_rttvar);
2857#endif
2858 } else if (tp->t_srtt != 0) {
2859 int delta;
2860
984263bc
MD
2861 /*
2862 * srtt is stored as fixed point with 5 bits after the
2863 * binary point (i.e., scaled by 8). The following magic
2864 * is equivalent to the smoothing algorithm in rfc793 with
2865 * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed
2866 * point). Adjust rtt to origin 0.
2867 */
2868 delta = ((rtt - 1) << TCP_DELTA_SHIFT)
2869 - (tp->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT));
2870
2871 if ((tp->t_srtt += delta) <= 0)
2872 tp->t_srtt = 1;
2873
2874 /*
2875 * We accumulate a smoothed rtt variance (actually, a
2876 * smoothed mean difference), then set the retransmit
2877 * timer to smoothed rtt + 4 times the smoothed variance.
2878 * rttvar is stored as fixed point with 4 bits after the
2879 * binary point (scaled by 16). The following is
2880 * equivalent to rfc793 smoothing with an alpha of .75
2881 * (rttvar = rttvar*3/4 + |delta| / 4). This replaces
2882 * rfc793's wired-in beta.
2883 */
2884 if (delta < 0)
2885 delta = -delta;
2886 delta -= tp->t_rttvar >> (TCP_RTTVAR_SHIFT - TCP_DELTA_SHIFT);
2887 if ((tp->t_rttvar += delta) <= 0)
2888 tp->t_rttvar = 1;
2889 if (tp->t_rttbest > tp->t_srtt + tp->t_rttvar)
2890 tp->t_rttbest = tp->t_srtt + tp->t_rttvar;
2891 } else {
2892 /*
2893 * No rtt measurement yet - use the unsmoothed rtt.
2894 * Set the variance to half the rtt (so our first
2895 * retransmit happens at 3*rtt).
2896 */
2897 tp->t_srtt = rtt << TCP_RTT_SHIFT;
2898 tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1);
2899 tp->t_rttbest = tp->t_srtt + tp->t_rttvar;
2900 }
2901 tp->t_rtttime = 0;
2902 tp->t_rxtshift = 0;
2903
073ec6c4
SZ
2904#ifdef DEBUG_EIFEL_RESPONSE
2905 if (rebaserto) {
2906 kprintf("| rxtcur prev %d, old %d, ",
2907 tp->t_rxtcur_prev, tp->t_rxtcur);
2908 }
2909#endif
2910
984263bc
MD
2911 /*
2912 * the retransmit should happen at rtt + 4 * rttvar.
2913 * Because of the way we do the smoothing, srtt and rttvar
2914 * will each average +1/2 tick of bias. When we compute
2915 * the retransmit timer, we want 1/2 tick of rounding and
2916 * 1 extra tick because of +-1/2 tick uncertainty in the
2917 * firing of the timer. The bias will give us exactly the
2918 * 1.5 tick we need. But, because the bias is
2919 * statistical, we have to test that we don't drop below
2920 * the minimum feasible timer (which is 2 ticks).
2921 */
2922 TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp),
2923 max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX);
2924
073ec6c4
SZ
2925 if (rebaserto) {
2926 if (tp->t_rxtcur < tp->t_rxtcur_prev + tcp_eifel_rtoinc) {
2927 /*
2928 * RFC4015 requires that the new RTO is at least
2929 * 2*G (tcp_eifel_rtoinc) greater then the RTO
2930 * (t_rxtcur_prev) when the spurious retransmit
2931 * timeout happens.
2932 *
2933 * The above condition could be true, if the SRTT
2934 * and RTTVAR used to calculate t_rxtcur_prev
2935 * resulted in a value less than t_rttmin. So
2936 * simply increasing SRTT by tcp_eifel_rtoinc when
e1dd9e15 2937 * preparing for the Eifel response could not ensure
073ec6c4
SZ
2938 * that the new RTO will be tcp_eifel_rtoinc greater
2939 * t_rxtcur_prev.
2940 */
2941 tp->t_rxtcur = tp->t_rxtcur_prev + tcp_eifel_rtoinc;
2942 }
2943#ifdef DEBUG_EIFEL_RESPONSE
2944 kprintf("new %d\n", tp->t_rxtcur);
2945#endif
2946 }
2947
984263bc
MD
2948 /*
2949 * We received an ack for a packet that wasn't retransmitted;
2950 * it is probably safe to discard any error indications we've
2951 * received recently. This isn't quite right, but close enough
2952 * for now (a route might have failed after we sent a segment,
2953 * and the return path might not be symmetrical).
2954 */
2955 tp->t_softerror = 0;
2956}
2957
2958/*
2959 * Determine a reasonable value for maxseg size.
2960 * If the route is known, check route for mtu.
2961 * If none, use an mss that can be handled on the outgoing
2962 * interface without forcing IP to fragment; if bigger than
2963 * an mbuf cluster (MCLBYTES), round down to nearest multiple of MCLBYTES
2964 * to utilize large mbufs. If no route is found, route has no mtu,
2965 * or the destination isn't local, use a default, hopefully conservative
2966 * size (usually 512 or the default IP max size, but no more than the mtu
2967 * of the interface), as we can't discover anything about intervening
2968 * gateways or networks. We also initialize the congestion/slow start
2969 * window to be a single segment if the destination isn't local.
2970 * While looking at the routing entry, we also initialize other path-dependent
2971 * parameters from pre-set or cached values in the routing entry.
2972 *
2973 * Also take into account the space needed for options that we
2974 * send regularly. Make maxseg shorter by that amount to assure
2975 * that we can send maxseg amount of data even when the options
2976 * are present. Store the upper limit of the length of options plus
2977 * data in maxopd.
2978 *
2979 * NOTE that this routine is only called when we process an incoming
2980 * segment, for outgoing segments only tcp_mssopt is called.
984263bc
MD
2981 */
2982void
95b22adf 2983tcp_mss(struct tcpcb *tp, int offer)
984263bc 2984{
2256ba69 2985 struct rtentry *rt;
984263bc 2986 struct ifnet *ifp;
2256ba69 2987 int rtt, mss;
984263bc
MD
2988 u_long bufsize;
2989 struct inpcb *inp = tp->t_inpcb;
2990 struct socket *so;
984263bc 2991#ifdef INET6
d24ce1dc 2992 boolean_t isipv6 = ((inp->inp_vflag & INP_IPV6) ? TRUE : FALSE);
984263bc
MD
2993 size_t min_protoh = isipv6 ?
2994 sizeof(struct ip6_hdr) + sizeof(struct tcphdr) :
2995 sizeof(struct tcpiphdr);
2996#else
d24ce1dc 2997 const boolean_t isipv6 = FALSE;
984263bc
MD
2998 const size_t min_protoh = sizeof(struct tcpiphdr);
2999#endif
3000
3001 if (isipv6)
3002 rt = tcp_rtlookup6(&inp->inp_inc);
3003 else
3004 rt = tcp_rtlookup(&inp->inp_inc);
3005 if (rt == NULL) {
3006 tp->t_maxopd = tp->t_maxseg =
d24ce1dc 3007 (isipv6 ? tcp_v6mssdflt : tcp_mssdflt);
984263bc
MD
3008 return;
3009 }
3010 ifp = rt->rt_ifp;
3011 so = inp->inp_socket;
3012
984263bc
MD
3013 /*
3014 * Offer == 0 means that there was no MSS on the SYN segment,
b235ad6d
MD
3015 * in this case we use either the interface mtu or tcp_mssdflt.
3016 *
3017 * An offer which is too large will be cut down later.
984263bc 3018 */
5b0b9fa5 3019 if (offer == 0) {
b235ad6d
MD
3020 if (isipv6) {
3021 if (in6_localaddr(&inp->in6p_faddr)) {
3022 offer = ND_IFINFO(rt->rt_ifp)->linkmtu -
3023 min_protoh;
3024 } else {
3025 offer = tcp_v6mssdflt;
3026 }
3027 } else {
3028 if (in_localaddr(inp->inp_faddr))
3029 offer = ifp->if_mtu - min_protoh;
3030 else
3031 offer = tcp_mssdflt;
3032 }
5b0b9fa5 3033 }
b235ad6d
MD
3034
3035 /*
3036 * Prevent DoS attack with too small MSS. Round up
3037 * to at least minmss.
3038 *
3039 * Sanity check: make sure that maxopd will be large
3040 * enough to allow some data on segments even is the
3041 * all the option space is used (40bytes). Otherwise
3042 * funny things may happen in tcp_output.
3043 */
3044 offer = max(offer, tcp_minmss);
3045 offer = max(offer, 64);
3046
27b8aee3 3047 rt->rt_rmx.rmx_mssopt = offer;
984263bc
MD
3048
3049 /*
3050 * While we're here, check if there's an initial rtt
3051 * or rttvar. Convert from the route-table units
3052 * to scaled multiples of the slow timeout timer.
3053 */
3054 if (tp->t_srtt == 0 && (rtt = rt->rt_rmx.rmx_rtt)) {
3055 /*
3056 * XXX the lock bit for RTT indicates that the value
3057 * is also a minimum value; this is subject to time.
3058 */
3059 if (rt->rt_rmx.rmx_locks & RTV_RTT)
3060 tp->t_rttmin = rtt / (RTM_RTTUNIT / hz);
3061 tp->t_srtt = rtt / (RTM_RTTUNIT / (hz * TCP_RTT_SCALE));
3062 tp->t_rttbest = tp->t_srtt + TCP_RTT_SCALE;
3063 tcpstat.tcps_usedrtt++;
3064 if (rt->rt_rmx.rmx_rttvar) {
3065 tp->t_rttvar = rt->rt_rmx.rmx_rttvar /
3066 (RTM_RTTUNIT / (hz * TCP_RTTVAR_SCALE));
3067 tcpstat.tcps_usedrttvar++;
3068 } else {
3069 /* default variation is +- 1 rtt */
3070 tp->t_rttvar =
3071 tp->t_srtt * TCP_RTTVAR_SCALE / TCP_RTT_SCALE;
3072 }
3073 TCPT_RANGESET(tp->t_rxtcur,
3074 ((tp->t_srtt >> 2) + tp->t_rttvar) >> 1,
3075 tp->t_rttmin, TCPTV_REXMTMAX);
3076 }
b235ad6d 3077
984263bc
MD
3078 /*
3079 * if there's an mtu associated with the route, use it
b235ad6d
MD
3080 * else, use the link mtu. Take the smaller of mss or offer
3081 * as our final mss.
984263bc 3082 */
b235ad6d 3083 if (rt->rt_rmx.rmx_mtu) {
984263bc 3084 mss = rt->rt_rmx.rmx_mtu - min_protoh;
b235ad6d
MD
3085 } else {
3086 if (isipv6)
698ac46c 3087 mss = ND_IFINFO(rt->rt_ifp)->linkmtu - min_protoh;
b235ad6d 3088 else
984263bc 3089 mss = ifp->if_mtu - min_protoh;
984263bc
MD
3090 }
3091 mss = min(mss, offer);
b235ad6d 3092
984263bc
MD
3093 /*
3094 * maxopd stores the maximum length of data AND options
3095 * in a segment; maxseg is the amount of data in a normal
3096 * segment. We need to store this value (maxopd) apart
3097 * from maxseg, because now every segment carries options
3098 * and thus we normally have somewhat less data in segments.
3099 */
3100 tp->t_maxopd = mss;
3101
61896e3c 3102 if ((tp->t_flags & (TF_REQ_TSTMP | TF_NOOPT)) == TF_REQ_TSTMP &&
27b8aee3 3103 ((tp->t_flags & TF_RCVD_TSTMP) == TF_RCVD_TSTMP))
984263bc 3104 mss -= TCPOLEN_TSTAMP_APPA;
984263bc
MD
3105
3106#if (MCLBYTES & (MCLBYTES - 1)) == 0
f99dae5e
SW
3107 if (mss > MCLBYTES)
3108 mss &= ~(MCLBYTES-1);
984263bc 3109#else
f99dae5e
SW
3110 if (mss > MCLBYTES)
3111 mss = mss / MCLBYTES * MCLBYTES;
984263bc
MD
3112#endif
3113 /*
3114 * If there's a pipesize, change the socket buffer
3115 * to that size. Make the socket buffers an integral
3116 * number of mss units; if the mss is larger than
3117 * the socket buffer, decrease the mss.
3118 */
3119#ifdef RTV_SPIPE
3120 if ((bufsize = rt->rt_rmx.rmx_sendpipe) == 0)
3121#endif
6d49aa6f 3122 bufsize = so->so_snd.ssb_hiwat;
984263bc
MD
3123 if (bufsize < mss)
3124 mss = bufsize;
3125 else {
3126 bufsize = roundup(bufsize, mss);
3127 if (bufsize > sb_max)
3128 bufsize = sb_max;
6d49aa6f
MD
3129 if (bufsize > so->so_snd.ssb_hiwat)
3130 ssb_reserve(&so->so_snd, bufsize, so, NULL);
984263bc
MD
3131 }
3132 tp->t_maxseg = mss;
3133
3134#ifdef RTV_RPIPE
3135 if ((bufsize = rt->rt_rmx.rmx_recvpipe) == 0)
3136#endif
6d49aa6f 3137 bufsize = so->so_rcv.ssb_hiwat;
984263bc
MD
3138 if (bufsize > mss) {
3139 bufsize = roundup(bufsize, mss);
3140 if (bufsize > sb_max)
3141 bufsize = sb_max;
6cef7136
MD
3142 if (bufsize > so->so_rcv.ssb_hiwat) {
3143 lwkt_gettoken(&so->so_rcv.ssb_token);
6d49aa6f 3144 ssb_reserve(&so->so_rcv, bufsize, so, NULL);
6cef7136
MD
3145 lwkt_reltoken(&so->so_rcv.ssb_token);
3146 }
984263bc
MD
3147 }
3148
3149 /*
697020f5
SZ
3150 * Set the slow-start flight size
3151 *
3152 * NOTE: t_maxseg must have been configured!
984263bc 3153 */
697020f5 3154 tp->snd_cwnd = tcp_initial_window(tp);
984263bc
MD
3155
3156 if (rt->rt_rmx.rmx_ssthresh) {
3157 /*
3158 * There's some sort of gateway or interface
3159 * buffer limit on the path. Use this to set
3160 * the slow start threshhold, but set the
3161 * threshold to no less than 2*mss.
3162 */
3163 tp->snd_ssthresh = max(2 * mss, rt->rt_rmx.rmx_ssthresh);
3164 tcpstat.tcps_usedssthresh++;
3165 }
3166}
3167
3168/*
3169 * Determine the MSS option to send on an outgoing SYN.
3170 */
3171int
95b22adf 3172tcp_mssopt(struct tcpcb *tp)
984263bc
MD
3173{
3174 struct rtentry *rt;
3175#ifdef INET6
d24ce1dc
JH
3176 boolean_t isipv6 =
3177 ((tp->t_inpcb->inp_vflag & INP_IPV6) ? TRUE : FALSE);
984263bc
MD
3178 int min_protoh = isipv6 ?
3179 sizeof(struct ip6_hdr) + sizeof(struct tcphdr) :
3180 sizeof(struct tcpiphdr);
3181#else
d24ce1dc 3182 const boolean_t isipv6 = FALSE;
984263bc
MD
3183 const size_t min_protoh = sizeof(struct tcpiphdr);
3184#endif
3185
3186 if (isipv6)
3187 rt = tcp_rtlookup6(&tp->t_inpcb->inp_inc);
3188 else
3189 rt = tcp_rtlookup(&tp->t_inpcb->inp_inc);
3190 if (rt == NULL)
3191 return (isipv6 ? tcp_v6mssdflt : tcp_mssdflt);
3192
3193 return (rt->rt_ifp->if_mtu - min_protoh);
3194}
3195
984263bc
MD
3196/*
3197 * When a partial ack arrives, force the retransmission of the
91489f6b
JH
3198 * next unacknowledged segment. Do not exit Fast Recovery.
3199 *
3200 * Implement the Slow-but-Steady variant of NewReno by restarting the
3201 * the retransmission timer. Turn it off here so it can be restarted
3202 * later in tcp_output().
984263bc
MD
3203 */
3204static void
91489f6b 3205tcp_newreno_partial_ack(struct tcpcb *tp, struct tcphdr *th, int acked)
984263bc 3206{
91489f6b
JH
3207 tcp_seq old_snd_nxt = tp->snd_nxt;
3208 u_long ocwnd = tp->snd_cwnd;
984263bc 3209
a48c5dd5 3210 tcp_callout_stop(tp, tp->tt_rexmt);
984263bc
MD
3211 tp->t_rtttime = 0;
3212 tp->snd_nxt = th->th_ack;
91489f6b
JH
3213 /* Set snd_cwnd to one segment beyond acknowledged offset. */
3214 tp->snd_cwnd = tp->t_maxseg;
984263bc 3215 tp->t_flags |= TF_ACKNOW;
f23061d4 3216 tcp_output(tp);
91489f6b
JH
3217 if (SEQ_GT(old_snd_nxt, tp->snd_nxt))
3218 tp->snd_nxt = old_snd_nxt;
3219 /* partial window deflation */
68947d12
ND
3220 if (ocwnd > acked)
3221 tp->snd_cwnd = ocwnd - acked + tp->t_maxseg;
3222 else
3223 tp->snd_cwnd = tp->t_maxseg;
91489f6b
JH
3224}
3225
3226/*
3227 * In contrast to the Slow-but-Steady NewReno variant,
3228 * we do not reset the retransmission timer for SACK retransmissions,
3229 * except when retransmitting snd_una.
3230 */
3231static void
ccb518ea 3232tcp_sack_rexmt(struct tcpcb *tp, boolean_t force)
91489f6b 3233{
91489f6b
JH
3234 tcp_seq old_snd_nxt = tp->snd_nxt;
3235 u_long ocwnd = tp->snd_cwnd;
1bdfd728 3236 uint32_t pipe;
91489f6b 3237 int nseg = 0; /* consecutive new segments */
a098966f 3238 int nseg_rexmt = 0; /* retransmitted segments */
ccb518ea 3239 int maxrexmt = 0;
91489f6b 3240
ccb518ea
SZ
3241 if (force) {
3242 uint32_t unsacked = tcp_sack_first_unsacked_len(tp);
3243
3244 /*
3245 * Try to fill the first hole in the receiver's
3246 * reassemble queue.
3247 */
3248 maxrexmt = howmany(unsacked, tp->t_maxseg);
3249 if (maxrexmt > tcp_force_sackrxt)
3250 maxrexmt = tcp_force_sackrxt;
3251 }
3252
91489f6b
JH
3253 tp->t_rtttime = 0;
3254 pipe = tcp_sack_compute_pipe(tp);
ccb518ea
SZ
3255 while (((tcp_seq_diff_t)(ocwnd - pipe) >= (tcp_seq_diff_t)tp->t_maxseg
3256 || (force && nseg_rexmt < maxrexmt && nseg == 0)) &&
aff9f480 3257 (!tcp_do_smartsack || nseg < TCP_SACK_MAXBURST)) {
1bdfd728
SZ
3258 tcp_seq old_snd_max, old_rexmt_high, nextrexmt;
3259 uint32_t sent, seglen;
3260 boolean_t rescue;
91489f6b
JH
3261 int error;
3262
1bdfd728 3263 old_rexmt_high = tp->rexmt_high;
64debfd6 3264 if (!tcp_sack_nextseg(tp, &nextrexmt, &seglen, &rescue)) {
1bdfd728
SZ
3265 tp->rexmt_high = old_rexmt_high;
3266 break;
3267 }
3268
a098966f
SZ
3269 /*
3270 * If the next tranmission is a rescue retranmission,
3271 * we check whether we have already sent some data
3272 * (either new segments or retransmitted segments)
3273 * into the the network or not. Since the idea of rescue
3274 * retransmission is to sustain ACK clock, as long as
3275 * some segments are in the network, ACK clock will be
3276 * kept ticking.
3277 */
3278 if (rescue && (nseg_rexmt > 0 || nseg > 0)) {
3279 tp->rexmt_high = old_rexmt_high;
3280 break;
3281 }
3282
98cb2337
MD
3283 if (nextrexmt == tp->snd_max)
3284 ++nseg;
a098966f
SZ
3285 else
3286 ++nseg_rexmt;
91489f6b
JH
3287 tp->snd_nxt = nextrexmt;
3288 tp->snd_cwnd = nextrexmt - tp->snd_una + seglen;
3289 old_snd_max = tp->snd_max;
3290 if (nextrexmt == tp->snd_una)
a48c5dd5 3291 tcp_callout_stop(tp, tp->tt_rexmt);
c1fabe85 3292 tp->t_flags |= TF_XMITNOW;
91489f6b 3293 error = tcp_output(tp);
1bdfd728
SZ
3294 if (error != 0) {
3295 tp->rexmt_high = old_rexmt_high;
91489f6b 3296 break;
1bdfd728 3297 }
91489f6b 3298 sent = tp->snd_nxt - nextrexmt;
1bdfd728
SZ
3299 if (sent <= 0) {
3300 tp->rexmt_high = old_rexmt_high;
91489f6b 3301 break;
1bdfd728
SZ
3302 }
3303 pipe += sent;
91489f6b
JH
3304 tcpstat.tcps_sndsackpack++;
3305 tcpstat.tcps_sndsackbyte += sent;
1bdfd728
SZ
3306
3307 if (rescue) {
a098966f 3308 tcpstat.tcps_sackrescue++;
1bdfd728 3309 tp->rexmt_rescue = tp->snd_nxt;
c7e6499a 3310 tp->sack_flags |= TSACK_F_SACKRESCUED;
1bdfd728
SZ
3311 break;
3312 }
91489f6b 3313 if (SEQ_LT(nextrexmt, old_snd_max) &&
a098966f 3314 SEQ_LT(tp->rexmt_high, tp->snd_nxt)) {
91489f6b 3315 tp->rexmt_high = seq_min(tp->snd_nxt, old_snd_max);
21f337ca 3316 if (tcp_aggressive_rescuesack &&
c7e6499a 3317 (tp->sack_flags & TSACK_F_SACKRESCUED) &&
a098966f
SZ
3318 SEQ_LT(tp->rexmt_rescue, tp->rexmt_high)) {
3319 /* Drag RescueRxt along with HighRxt */
3320 tp->rexmt_rescue = tp->rexmt_high;
3321 }
3322 }
91489f6b
JH
3323 }
3324 if (SEQ_GT(old_snd_nxt, tp->snd_nxt))
3325 tp->snd_nxt = old_snd_nxt;
984263bc 3326 tp->snd_cwnd = ocwnd;
984263bc 3327}
0ecd93f9 3328
e2289e66
SZ
3329/*
3330 * Return TRUE, if some new segments are sent
3331 */
ffe35e17
SZ
3332static boolean_t
3333tcp_sack_limitedxmit(struct tcpcb *tp)
3334{
3335 tcp_seq oldsndnxt = tp->snd_nxt;
3336 tcp_seq oldsndmax = tp->snd_max;
3337 u_long ocwnd = tp->snd_cwnd;
db421eef 3338 uint32_t pipe, sent;
ffe35e17 3339 boolean_t ret = FALSE;
db421eef
SZ
3340 tcp_seq_diff_t cwnd_left;
3341 tcp_seq next;
ffe35e17
SZ
3342
3343 tp->rexmt_high = tp->snd_una - 1;
3344 pipe = tcp_sack_compute_pipe(tp);
db421eef
SZ
3345 cwnd_left = (tcp_seq_diff_t)(ocwnd - pipe);
3346 if (cwnd_left < (tcp_seq_diff_t)tp->t_maxseg)
3347 return FALSE;
ffe35e17 3348
aff9f480
SZ
3349 if (tcp_do_smartsack)
3350 cwnd_left = ulmin(cwnd_left, tp->t_maxseg * TCP_SACK_MAXBURST);
3351
db421eef
SZ
3352 next = tp->snd_nxt = tp->snd_max;
3353 tp->snd_cwnd = tp->snd_nxt - tp->snd_una +
3354 rounddown(cwnd_left, tp->t_maxseg);
ffe35e17 3355
c1fabe85 3356 tp->t_flags |= TF_XMITNOW;
db421eef 3357 tcp_output(tp);
ffe35e17 3358
db421eef
SZ
3359 sent = tp->snd_nxt - next;
3360 if (sent > 0) {
3361 tcpstat.tcps_sndlimited += howmany(sent, tp->t_maxseg);
ffe35e17
SZ
3362 ret = TRUE;
3363 }
3364
3365 if (SEQ_LT(oldsndnxt, oldsndmax)) {
3366 KASSERT(SEQ_GEQ(oldsndnxt, tp->snd_una),
3367 ("snd_una moved in other threads"));
3368 tp->snd_nxt = oldsndnxt;
3369 }
3370 tp->snd_cwnd = ocwnd;
3371
e2289e66
SZ
3372 if (ret && TCP_DO_NCR(tp))
3373 tcp_ncr_update_rxtthresh(tp);
3374
ffe35e17
SZ
3375 return ret;
3376}
3377
0ecd93f9
MD
3378/*
3379 * Reset idle time and keep-alive timer, typically called when a valid
3380 * tcp packet is received but may also be called when FASTKEEP is set
3381 * to prevent the previous long-timeout from calculating to a drop.
3382 *
3383 * Only update t_rcvtime for non-SYN packets.
3384 *
3385 * Handle the case where one side thinks the connection is established
3386 * but the other side has, say, rebooted without cleaning out the
3387 * connection. The SYNs could be construed as an attack and wind
3388 * up ignored, but in case it isn't an attack we can validate the
3389 * connection by forcing a keepalive.
3390 */
3391void
3392tcp_timer_keep_activity(struct tcpcb *tp, int thflags)
3393{
3394 if (TCPS_HAVEESTABLISHED(tp->t_state)) {
3395 if ((thflags & (TH_SYN | TH_ACK)) == TH_SYN) {
3396 tp->t_flags |= TF_KEEPALIVE;
3397 tcp_callout_reset(tp, tp->tt_keep, hz / 2,
3398 tcp_timer_keep);
3399 } else {
3400 tp->t_rcvtime = ticks;
3401 tp->t_flags &= ~TF_KEEPALIVE;
3402 tcp_callout_reset(tp, tp->tt_keep,
fb8d5c6d 3403 tp->t_keepidle,
0ecd93f9
MD
3404 tcp_timer_keep);
3405 }
3406 }
3407}
01d3427a
SZ
3408
3409static int
3410tcp_rmx_msl(const struct tcpcb *tp)
3411{
3412 struct rtentry *rt;
3413 struct inpcb *inp = tp->t_inpcb;
9855a4ef 3414 int msl;
01d3427a
SZ
3415#ifdef INET6
3416 boolean_t isipv6 = ((inp->inp_vflag & INP_IPV6) ? TRUE : FALSE);
3417#else
3418 const boolean_t isipv6 = FALSE;
3419#endif
3420
3421 if (isipv6)
3422 rt = tcp_rtlookup6(&inp->inp_inc);
3423 else
3424 rt = tcp_rtlookup(&inp->inp_inc);
3425 if (rt == NULL || rt->rt_rmx.rmx_msl == 0)
3426 return tcp_msl;
3427
9855a4ef
SZ
3428 msl = (rt->rt_rmx.rmx_msl * hz) / 1000;
3429 if (msl == 0)
3430 msl = 1;
3431
3432 return msl;
01d3427a 3433}
8651f7f8
SZ
3434
3435static void
3436tcp_established(struct tcpcb *tp)
3437{
3438 tp->t_state = TCPS_ESTABLISHED;
fb8d5c6d 3439 tcp_callout_reset(tp, tp->tt_keep, tp->t_keepidle, tcp_timer_keep);
be34e534 3440
d5082e3d 3441 if (tp->t_rxtsyn > 0) {
48a4676d
SZ
3442 /*
3443 * RFC6298:
3444 * "If the timer expires awaiting the ACK of a SYN segment
3445 * and the TCP implementation is using an RTO less than 3
3446 * seconds, the RTO MUST be re-initialized to 3 seconds
3447 * when data transmission begins"
3448 */
3449 if (tp->t_rxtcur < TCPTV_RTOBASE3)
3450 tp->t_rxtcur = TCPTV_RTOBASE3;
be34e534 3451 }
8651f7f8 3452}
27f4bf33
SZ
3453
3454/*
3455 * Returns TRUE, if the ACK should be dropped
3456 */
3457static boolean_t
0a832381 3458tcp_recv_dupack(struct tcpcb *tp, tcp_seq th_ack, u_int to_flags)
27f4bf33 3459{
ba0d6f99
SZ
3460 boolean_t fast_sack_rexmt = TRUE;
3461