2 * Copyright (c) 2003, 2004 Jeffrey M. Hsu. All rights reserved.
3 * Copyright (c) 2003, 2004 The DragonFly Project. All rights reserved.
5 * This code is derived from software contributed to The DragonFly Project
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
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.
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
35 * All advertising materials mentioning features or use of this software
36 * must display the following acknowledgement:
37 * This product includes software developed by Jeffrey M. Hsu.
39 * Copyright (c) 2001 Networks Associates Technologies, Inc.
40 * All rights reserved.
42 * This software was developed for the FreeBSD Project by Jonathan Lemon
43 * and NAI Labs, the Security Research Division of Network Associates, Inc.
44 * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
45 * DARPA CHATS research program.
47 * Redistribution and use in source and binary forms, with or without
48 * modification, are permitted provided that the following conditions
50 * 1. Redistributions of source code must retain the above copyright
51 * notice, this list of conditions and the following disclaimer.
52 * 2. Redistributions in binary form must reproduce the above copyright
53 * notice, this list of conditions and the following disclaimer in the
54 * documentation and/or other materials provided with the distribution.
55 * 3. The name of the author may not be used to endorse or promote
56 * products derived from this software without specific prior written
59 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
60 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
61 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
62 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
63 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
64 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
65 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
66 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
67 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
68 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
71 * $FreeBSD: src/sys/netinet/tcp_syncache.c,v 1.5.2.14 2003/02/24 04:02:27 silby Exp $
75 #include "opt_inet6.h"
76 #include "opt_ipsec.h"
78 #include <sys/param.h>
79 #include <sys/systm.h>
80 #include <sys/kernel.h>
81 #include <sys/sysctl.h>
82 #include <sys/malloc.h>
85 #include <sys/proc.h> /* for proc0 declaration */
86 #include <sys/random.h>
87 #include <sys/socket.h>
88 #include <sys/socketvar.h>
89 #include <sys/in_cksum.h>
91 #include <sys/msgport2.h>
92 #include <net/netmsg2.h>
93 #include <net/netisr2.h>
96 #include <net/route.h>
98 #include <netinet/in.h>
99 #include <netinet/in_systm.h>
100 #include <netinet/ip.h>
101 #include <netinet/in_var.h>
102 #include <netinet/in_pcb.h>
103 #include <netinet/ip_var.h>
104 #include <netinet/ip6.h>
106 #include <netinet/icmp6.h>
107 #include <netinet6/nd6.h>
109 #include <netinet6/ip6_var.h>
110 #include <netinet6/in6_pcb.h>
111 #include <netinet/tcp.h>
112 #include <netinet/tcp_fsm.h>
113 #include <netinet/tcp_seq.h>
114 #include <netinet/tcp_timer.h>
115 #include <netinet/tcp_timer2.h>
116 #include <netinet/tcp_var.h>
117 #include <netinet6/tcp6_var.h>
120 #include <netinet6/ipsec.h>
122 #include <netinet6/ipsec6.h>
124 #include <netproto/key/key.h>
128 #include <netproto/ipsec/ipsec.h>
130 #include <netproto/ipsec/ipsec6.h>
132 #include <netproto/ipsec/key.h>
134 #endif /*FAST_IPSEC*/
136 static int tcp_syncookies = 1;
137 SYSCTL_INT(_net_inet_tcp, OID_AUTO, syncookies, CTLFLAG_RW,
139 "Use TCP SYN cookies if the syncache overflows");
141 static void syncache_drop(struct syncache *, struct syncache_head *);
142 static void syncache_free(struct syncache *);
143 static void syncache_insert(struct syncache *, struct syncache_head *);
144 struct syncache *syncache_lookup(struct in_conninfo *, struct syncache_head **);
145 static int syncache_respond(struct syncache *, struct mbuf *);
146 static struct socket *syncache_socket(struct syncache *, struct socket *,
148 static void syncache_timer(void *);
149 static u_int32_t syncookie_generate(struct syncache *);
150 static struct syncache *syncookie_lookup(struct in_conninfo *,
151 struct tcphdr *, struct socket *);
154 * Transmit the SYN,ACK fewer times than TCP_MAXRXTSHIFT specifies.
155 * 4 retransmits corresponds to a timeout of (3 + 3 + 3 + 3 + 3 == 15) seconds
156 * or (1 + 1 + 2 + 4 + 8 == 16) seconds if RFC6298 is used, the odds are that
157 * the user has given up attempting to connect by then.
159 #define SYNCACHE_MAXREXMTS 4
161 /* Arbitrary values */
162 #define TCP_SYNCACHE_HASHSIZE 512
163 #define TCP_SYNCACHE_BUCKETLIMIT 30
165 struct netmsg_sc_timer {
166 struct netmsg_base base;
167 struct msgrec *nm_mrec; /* back pointer to containing msgrec */
171 struct netmsg_sc_timer msg;
172 lwkt_port_t port; /* constant after init */
173 int slot; /* constant after init */
176 static void syncache_timer_handler(netmsg_t);
178 struct tcp_syncache {
186 static struct tcp_syncache tcp_syncache;
188 TAILQ_HEAD(syncache_list, syncache);
190 struct tcp_syncache_percpu {
191 struct syncache_head *hashbase;
193 struct syncache_list timerq[SYNCACHE_MAXREXMTS + 1];
194 struct callout tt_timerq[SYNCACHE_MAXREXMTS + 1];
195 struct msgrec mrec[SYNCACHE_MAXREXMTS + 1];
197 static struct tcp_syncache_percpu tcp_syncache_percpu[MAXCPU];
199 static struct lwkt_port syncache_null_rport;
201 SYSCTL_NODE(_net_inet_tcp, OID_AUTO, syncache, CTLFLAG_RW, 0, "TCP SYN cache");
203 SYSCTL_INT(_net_inet_tcp_syncache, OID_AUTO, bucketlimit, CTLFLAG_RD,
204 &tcp_syncache.bucket_limit, 0, "Per-bucket hash limit for syncache");
206 SYSCTL_INT(_net_inet_tcp_syncache, OID_AUTO, cachelimit, CTLFLAG_RD,
207 &tcp_syncache.cache_limit, 0, "Overall entry limit for syncache");
211 SYSCTL_INT(_net_inet_tcp_syncache, OID_AUTO, count, CTLFLAG_RD,
212 &tcp_syncache.cache_count, 0, "Current number of entries in syncache");
215 SYSCTL_INT(_net_inet_tcp_syncache, OID_AUTO, hashsize, CTLFLAG_RD,
216 &tcp_syncache.hashsize, 0, "Size of TCP syncache hashtable");
218 SYSCTL_INT(_net_inet_tcp_syncache, OID_AUTO, rexmtlimit, CTLFLAG_RW,
219 &tcp_syncache.rexmt_limit, 0, "Limit on SYN/ACK retransmissions");
221 static MALLOC_DEFINE(M_SYNCACHE, "syncache", "TCP syncache");
223 #define SYNCACHE_HASH(inc, mask) \
224 ((tcp_syncache.hash_secret ^ \
225 (inc)->inc_faddr.s_addr ^ \
226 ((inc)->inc_faddr.s_addr >> 16) ^ \
227 (inc)->inc_fport ^ (inc)->inc_lport) & mask)
229 #define SYNCACHE_HASH6(inc, mask) \
230 ((tcp_syncache.hash_secret ^ \
231 (inc)->inc6_faddr.s6_addr32[0] ^ \
232 (inc)->inc6_faddr.s6_addr32[3] ^ \
233 (inc)->inc_fport ^ (inc)->inc_lport) & mask)
235 #define ENDPTS_EQ(a, b) ( \
236 (a)->ie_fport == (b)->ie_fport && \
237 (a)->ie_lport == (b)->ie_lport && \
238 (a)->ie_faddr.s_addr == (b)->ie_faddr.s_addr && \
239 (a)->ie_laddr.s_addr == (b)->ie_laddr.s_addr \
242 #define ENDPTS6_EQ(a, b) (memcmp(a, b, sizeof(*a)) == 0)
245 syncache_rto(int slot)
248 return (TCPTV_RTOBASE * tcp_syn_backoff_low[slot]);
250 return (TCPTV_RTOBASE * tcp_syn_backoff[slot]);
254 syncache_timeout(struct tcp_syncache_percpu *syncache_percpu,
255 struct syncache *sc, int slot)
261 * Record the time that we spent in SYN|ACK
264 * Needed by RFC3390 and RFC6298.
266 sc->sc_rxtused += syncache_rto(slot - 1);
268 sc->sc_rxtslot = slot;
270 rto = syncache_rto(slot);
271 sc->sc_rxttime = ticks + rto;
273 TAILQ_INSERT_TAIL(&syncache_percpu->timerq[slot], sc, sc_timerq);
274 if (!callout_active(&syncache_percpu->tt_timerq[slot])) {
275 callout_reset(&syncache_percpu->tt_timerq[slot], rto,
276 syncache_timer, &syncache_percpu->mrec[slot]);
281 syncache_free(struct syncache *sc)
285 const boolean_t isipv6 = sc->sc_inc.inc_isipv6;
287 const boolean_t isipv6 = FALSE;
291 m_free(sc->sc_ipopts);
293 rt = isipv6 ? sc->sc_route6.ro_rt : sc->sc_route.ro_rt;
296 * If this is the only reference to a protocol-cloned
297 * route, remove it immediately.
299 if ((rt->rt_flags & RTF_WASCLONED) && rt->rt_refcnt == 1)
300 rtrequest(RTM_DELETE, rt_key(rt), rt->rt_gateway,
301 rt_mask(rt), rt->rt_flags, NULL);
304 kfree(sc, M_SYNCACHE);
312 tcp_syncache.hashsize = TCP_SYNCACHE_HASHSIZE;
313 tcp_syncache.bucket_limit = TCP_SYNCACHE_BUCKETLIMIT;
314 tcp_syncache.cache_limit =
315 tcp_syncache.hashsize * tcp_syncache.bucket_limit;
316 tcp_syncache.rexmt_limit = SYNCACHE_MAXREXMTS;
317 tcp_syncache.hash_secret = karc4random();
319 TUNABLE_INT_FETCH("net.inet.tcp.syncache.hashsize",
320 &tcp_syncache.hashsize);
321 TUNABLE_INT_FETCH("net.inet.tcp.syncache.cachelimit",
322 &tcp_syncache.cache_limit);
323 TUNABLE_INT_FETCH("net.inet.tcp.syncache.bucketlimit",
324 &tcp_syncache.bucket_limit);
325 if (!powerof2(tcp_syncache.hashsize)) {
326 kprintf("WARNING: syncache hash size is not a power of 2.\n");
327 tcp_syncache.hashsize = 512; /* safe default */
329 tcp_syncache.hashmask = tcp_syncache.hashsize - 1;
331 lwkt_initport_replyonly_null(&syncache_null_rport);
333 for (cpu = 0; cpu < ncpus2; cpu++) {
334 struct tcp_syncache_percpu *syncache_percpu;
336 syncache_percpu = &tcp_syncache_percpu[cpu];
337 /* Allocate the hash table. */
338 syncache_percpu->hashbase = kmalloc(tcp_syncache.hashsize * sizeof(struct syncache_head),
339 M_SYNCACHE, M_WAITOK);
341 /* Initialize the hash buckets. */
342 for (i = 0; i < tcp_syncache.hashsize; i++) {
343 struct syncache_head *bucket;
345 bucket = &syncache_percpu->hashbase[i];
346 TAILQ_INIT(&bucket->sch_bucket);
347 bucket->sch_length = 0;
350 for (i = 0; i <= SYNCACHE_MAXREXMTS; i++) {
351 /* Initialize the timer queues. */
352 TAILQ_INIT(&syncache_percpu->timerq[i]);
353 callout_init_mp(&syncache_percpu->tt_timerq[i]);
355 syncache_percpu->mrec[i].slot = i;
356 syncache_percpu->mrec[i].port = netisr_cpuport(cpu);
357 syncache_percpu->mrec[i].msg.nm_mrec =
358 &syncache_percpu->mrec[i];
359 netmsg_init(&syncache_percpu->mrec[i].msg.base,
360 NULL, &syncache_null_rport,
361 0, syncache_timer_handler);
367 syncache_insert(struct syncache *sc, struct syncache_head *sch)
369 struct tcp_syncache_percpu *syncache_percpu;
370 struct syncache *sc2;
373 syncache_percpu = &tcp_syncache_percpu[mycpu->gd_cpuid];
376 * Make sure that we don't overflow the per-bucket
377 * limit or the total cache size limit.
379 if (sch->sch_length >= tcp_syncache.bucket_limit) {
381 * The bucket is full, toss the oldest element.
383 sc2 = TAILQ_FIRST(&sch->sch_bucket);
384 sc2->sc_tp->ts_recent = ticks;
385 syncache_drop(sc2, sch);
386 tcpstat.tcps_sc_bucketoverflow++;
387 } else if (syncache_percpu->cache_count >= tcp_syncache.cache_limit) {
389 * The cache is full. Toss the oldest entry in the
390 * entire cache. This is the front entry in the
391 * first non-empty timer queue with the largest
394 for (i = SYNCACHE_MAXREXMTS; i >= 0; i--) {
395 sc2 = TAILQ_FIRST(&syncache_percpu->timerq[i]);
396 while (sc2 && (sc2->sc_flags & SCF_MARKER))
397 sc2 = TAILQ_NEXT(sc2, sc_timerq);
401 sc2->sc_tp->ts_recent = ticks;
402 syncache_drop(sc2, NULL);
403 tcpstat.tcps_sc_cacheoverflow++;
406 /* Initialize the entry's timer. */
407 syncache_timeout(syncache_percpu, sc, 0);
409 /* Put it into the bucket. */
410 TAILQ_INSERT_TAIL(&sch->sch_bucket, sc, sc_hash);
412 syncache_percpu->cache_count++;
413 tcpstat.tcps_sc_added++;
417 syncache_destroy(struct tcpcb *tp)
419 struct tcp_syncache_percpu *syncache_percpu;
420 struct syncache_head *bucket;
424 syncache_percpu = &tcp_syncache_percpu[mycpu->gd_cpuid];
427 for (i = 0; i < tcp_syncache.hashsize; i++) {
428 bucket = &syncache_percpu->hashbase[i];
429 TAILQ_FOREACH(sc, &bucket->sch_bucket, sc_hash) {
437 syncache_drop(struct syncache *sc, struct syncache_head *sch)
439 struct tcp_syncache_percpu *syncache_percpu;
441 const boolean_t isipv6 = sc->sc_inc.inc_isipv6;
443 const boolean_t isipv6 = FALSE;
446 syncache_percpu = &tcp_syncache_percpu[mycpu->gd_cpuid];
450 sch = &syncache_percpu->hashbase[
451 SYNCACHE_HASH6(&sc->sc_inc, tcp_syncache.hashmask)];
453 sch = &syncache_percpu->hashbase[
454 SYNCACHE_HASH(&sc->sc_inc, tcp_syncache.hashmask)];
458 TAILQ_REMOVE(&sch->sch_bucket, sc, sc_hash);
460 syncache_percpu->cache_count--;
469 * Remove the entry from the syncache timer/timeout queue. Note
470 * that we do not try to stop any running timer since we do not know
471 * whether the timer's message is in-transit or not. Since timeouts
472 * are fairly long, taking an unneeded callout does not detrimentally
473 * effect performance.
475 TAILQ_REMOVE(&syncache_percpu->timerq[sc->sc_rxtslot], sc, sc_timerq);
481 * Place a timeout message on the TCP thread's message queue.
482 * This routine runs in soft interrupt context.
484 * An invariant is for this routine to be called, the callout must
485 * have been active. Note that the callout is not deactivated until
486 * after the message has been processed in syncache_timer_handler() below.
489 syncache_timer(void *p)
491 struct netmsg_sc_timer *msg = p;
493 lwkt_sendmsg(msg->nm_mrec->port, &msg->base.lmsg);
497 * Service a timer message queued by timer expiration.
498 * This routine runs in the TCP protocol thread.
500 * Walk the timer queues, looking for SYN,ACKs that need to be retransmitted.
501 * If we have retransmitted an entry the maximum number of times, expire it.
503 * When we finish processing timed-out entries, we restart the timer if there
504 * are any entries still on the queue and deactivate it otherwise. Only after
505 * a timer has been deactivated here can it be restarted by syncache_timeout().
508 syncache_timer_handler(netmsg_t msg)
510 struct tcp_syncache_percpu *syncache_percpu;
512 struct syncache marker;
513 struct syncache_list *list;
517 slot = ((struct netmsg_sc_timer *)msg)->nm_mrec->slot;
518 syncache_percpu = &tcp_syncache_percpu[mycpu->gd_cpuid];
520 list = &syncache_percpu->timerq[slot];
523 * Use a marker to keep our place in the scan. syncache_drop()
524 * can block and cause any next pointer we cache to become stale.
526 marker.sc_flags = SCF_MARKER;
527 TAILQ_INSERT_HEAD(list, &marker, sc_timerq);
529 while ((sc = TAILQ_NEXT(&marker, sc_timerq)) != NULL) {
533 TAILQ_REMOVE(list, &marker, sc_timerq);
534 TAILQ_INSERT_AFTER(list, sc, &marker, sc_timerq);
536 if (sc->sc_flags & SCF_MARKER)
539 if (ticks < sc->sc_rxttime)
540 break; /* finished because timerq sorted by time */
541 if (sc->sc_tp == NULL) {
542 syncache_drop(sc, NULL);
543 tcpstat.tcps_sc_stale++;
546 inp = sc->sc_tp->t_inpcb;
547 if (slot == SYNCACHE_MAXREXMTS ||
548 slot >= tcp_syncache.rexmt_limit ||
550 inp->inp_gencnt != sc->sc_inp_gencnt) {
551 syncache_drop(sc, NULL);
552 tcpstat.tcps_sc_stale++;
556 * syncache_respond() may call back into the syncache to
557 * to modify another entry, so do not obtain the next
558 * entry on the timer chain until it has completed.
560 syncache_respond(sc, NULL);
561 tcpstat.tcps_sc_retransmitted++;
562 TAILQ_REMOVE(list, sc, sc_timerq);
563 syncache_timeout(syncache_percpu, sc, slot + 1);
565 TAILQ_REMOVE(list, &marker, sc_timerq);
568 callout_reset(&syncache_percpu->tt_timerq[slot],
569 sc->sc_rxttime - ticks, syncache_timer,
570 &syncache_percpu->mrec[slot]);
572 callout_deactivate(&syncache_percpu->tt_timerq[slot]);
574 lwkt_replymsg(&msg->base.lmsg, 0);
578 * Find an entry in the syncache.
581 syncache_lookup(struct in_conninfo *inc, struct syncache_head **schp)
583 struct tcp_syncache_percpu *syncache_percpu;
585 struct syncache_head *sch;
587 syncache_percpu = &tcp_syncache_percpu[mycpu->gd_cpuid];
589 if (inc->inc_isipv6) {
590 sch = &syncache_percpu->hashbase[
591 SYNCACHE_HASH6(inc, tcp_syncache.hashmask)];
593 TAILQ_FOREACH(sc, &sch->sch_bucket, sc_hash)
594 if (ENDPTS6_EQ(&inc->inc_ie, &sc->sc_inc.inc_ie))
599 sch = &syncache_percpu->hashbase[
600 SYNCACHE_HASH(inc, tcp_syncache.hashmask)];
602 TAILQ_FOREACH(sc, &sch->sch_bucket, sc_hash) {
604 if (sc->sc_inc.inc_isipv6)
607 if (ENDPTS_EQ(&inc->inc_ie, &sc->sc_inc.inc_ie))
615 * This function is called when we get a RST for a
616 * non-existent connection, so that we can see if the
617 * connection is in the syn cache. If it is, zap it.
620 syncache_chkrst(struct in_conninfo *inc, struct tcphdr *th)
623 struct syncache_head *sch;
625 sc = syncache_lookup(inc, &sch);
630 * If the RST bit is set, check the sequence number to see
631 * if this is a valid reset segment.
633 * In all states except SYN-SENT, all reset (RST) segments
634 * are validated by checking their SEQ-fields. A reset is
635 * valid if its sequence number is in the window.
637 * The sequence number in the reset segment is normally an
638 * echo of our outgoing acknowlegement numbers, but some hosts
639 * send a reset with the sequence number at the rightmost edge
640 * of our receive window, and we have to handle this case.
642 if (SEQ_GEQ(th->th_seq, sc->sc_irs) &&
643 SEQ_LEQ(th->th_seq, sc->sc_irs + sc->sc_wnd)) {
644 syncache_drop(sc, sch);
645 tcpstat.tcps_sc_reset++;
650 syncache_badack(struct in_conninfo *inc)
653 struct syncache_head *sch;
655 sc = syncache_lookup(inc, &sch);
657 syncache_drop(sc, sch);
658 tcpstat.tcps_sc_badack++;
663 syncache_unreach(struct in_conninfo *inc, struct tcphdr *th)
666 struct syncache_head *sch;
668 /* we are called at splnet() here */
669 sc = syncache_lookup(inc, &sch);
673 /* If the sequence number != sc_iss, then it's a bogus ICMP msg */
674 if (ntohl(th->th_seq) != sc->sc_iss)
678 * If we've rertransmitted 3 times and this is our second error,
679 * we remove the entry. Otherwise, we allow it to continue on.
680 * This prevents us from incorrectly nuking an entry during a
681 * spurious network outage.
685 if ((sc->sc_flags & SCF_UNREACH) == 0 || sc->sc_rxtslot < 3) {
686 sc->sc_flags |= SCF_UNREACH;
689 syncache_drop(sc, sch);
690 tcpstat.tcps_sc_unreach++;
694 * Build a new TCP socket structure from a syncache entry.
696 * This is called from the context of the SYN+ACK
698 static struct socket *
699 syncache_socket(struct syncache *sc, struct socket *lso, struct mbuf *m)
701 struct inpcb *inp = NULL, *linp;
703 struct tcpcb *tp, *ltp;
706 const boolean_t isipv6 = sc->sc_inc.inc_isipv6;
708 const boolean_t isipv6 = FALSE;
710 struct sockaddr_in sin_faddr;
711 struct sockaddr_in6 sin6_faddr;
712 struct sockaddr *faddr;
715 faddr = (struct sockaddr *)&sin6_faddr;
716 sin6_faddr.sin6_family = AF_INET6;
717 sin6_faddr.sin6_len = sizeof(sin6_faddr);
718 sin6_faddr.sin6_addr = sc->sc_inc.inc6_faddr;
719 sin6_faddr.sin6_port = sc->sc_inc.inc_fport;
720 sin6_faddr.sin6_flowinfo = sin6_faddr.sin6_scope_id = 0;
722 faddr = (struct sockaddr *)&sin_faddr;
723 sin_faddr.sin_family = AF_INET;
724 sin_faddr.sin_len = sizeof(sin_faddr);
725 sin_faddr.sin_addr = sc->sc_inc.inc_faddr;
726 sin_faddr.sin_port = sc->sc_inc.inc_fport;
727 bzero(sin_faddr.sin_zero, sizeof(sin_faddr.sin_zero));
731 * Ok, create the full blown connection, and set things up
732 * as they would have been set up if we had created the
733 * connection when the SYN arrived. If we can't create
734 * the connection, abort it.
736 * Set the protocol processing port for the socket to the current
737 * port (that the connection came in on).
739 so = sonewconn_faddr(lso, SS_ISCONNECTED, faddr);
742 * Drop the connection; we will send a RST if the peer
743 * retransmits the ACK,
745 tcpstat.tcps_listendrop++;
750 * Insert new socket into hash list.
753 inp->inp_inc.inc_isipv6 = sc->sc_inc.inc_isipv6;
755 inp->in6p_laddr = sc->sc_inc.inc6_laddr;
758 inp->inp_vflag &= ~INP_IPV6;
759 inp->inp_vflag |= INP_IPV4;
760 inp->inp_flags &= ~IN6P_IPV6_V6ONLY;
762 inp->inp_laddr = sc->sc_inc.inc_laddr;
764 inp->inp_lport = sc->sc_inc.inc_lport;
765 if (in_pcbinsporthash(inp) != 0) {
767 * Undo the assignments above if we failed to
768 * put the PCB on the hash lists.
771 inp->in6p_laddr = kin6addr_any;
773 inp->inp_laddr.s_addr = INADDR_ANY;
779 /* copy old policy into new socket's */
780 if (ipsec_copy_policy(linp->inp_sp, inp->inp_sp))
781 kprintf("syncache_expand: could not copy policy\n");
784 struct in6_addr laddr6;
786 * Inherit socket options from the listening socket.
787 * Note that in6p_inputopts are not (and should not be)
788 * copied, since it stores previously received options and is
789 * used to detect if each new option is different than the
790 * previous one and hence should be passed to a user.
791 * If we copied in6p_inputopts, a user would not be able to
792 * receive options just after calling the accept system call.
794 inp->inp_flags |= linp->inp_flags & INP_CONTROLOPTS;
795 if (linp->in6p_outputopts)
796 inp->in6p_outputopts =
797 ip6_copypktopts(linp->in6p_outputopts, M_INTWAIT);
798 inp->in6p_route = sc->sc_route6;
799 sc->sc_route6.ro_rt = NULL;
801 laddr6 = inp->in6p_laddr;
802 if (IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_laddr))
803 inp->in6p_laddr = sc->sc_inc.inc6_laddr;
804 if (in6_pcbconnect(inp, faddr, &thread0)) {
805 inp->in6p_laddr = laddr6;
809 struct in_addr laddr;
811 inp->inp_options = ip_srcroute(m);
812 if (inp->inp_options == NULL) {
813 inp->inp_options = sc->sc_ipopts;
814 sc->sc_ipopts = NULL;
816 inp->inp_route = sc->sc_route;
817 sc->sc_route.ro_rt = NULL;
819 laddr = inp->inp_laddr;
820 if (inp->inp_laddr.s_addr == INADDR_ANY)
821 inp->inp_laddr = sc->sc_inc.inc_laddr;
822 if (in_pcbconnect(inp, faddr, &thread0)) {
823 inp->inp_laddr = laddr;
829 * The current port should be in the context of the SYN+ACK and
830 * so should match the tcp address port.
833 port = tcp6_addrport();
835 port = tcp_addrport(inp->inp_faddr.s_addr, inp->inp_fport,
836 inp->inp_laddr.s_addr, inp->inp_lport);
838 KASSERT(port == &curthread->td_msgport,
839 ("TCP PORT MISMATCH %p vs %p\n", port, &curthread->td_msgport));
842 tp->t_state = TCPS_SYN_RECEIVED;
843 tp->iss = sc->sc_iss;
844 tp->irs = sc->sc_irs;
847 tp->snd_wnd = sc->sc_sndwnd;
848 tp->snd_wl1 = sc->sc_irs;
849 tp->rcv_up = sc->sc_irs + 1;
850 tp->rcv_wnd = sc->sc_wnd;
851 tp->rcv_adv += tp->rcv_wnd;
853 tp->t_flags = sototcpcb(lso)->t_flags & (TF_NOPUSH | TF_NODELAY);
854 if (sc->sc_flags & SCF_NOOPT)
855 tp->t_flags |= TF_NOOPT;
856 if (sc->sc_flags & SCF_WINSCALE) {
857 tp->t_flags |= TF_REQ_SCALE | TF_RCVD_SCALE;
858 tp->snd_scale = sc->sc_requested_s_scale;
859 tp->request_r_scale = sc->sc_request_r_scale;
861 if (sc->sc_flags & SCF_TIMESTAMP) {
862 tp->t_flags |= TF_REQ_TSTMP | TF_RCVD_TSTMP;
863 tp->ts_recent = sc->sc_tsrecent;
864 tp->ts_recent_age = ticks;
866 if (sc->sc_flags & SCF_SACK_PERMITTED)
867 tp->t_flags |= TF_SACK_PERMITTED;
870 if (sc->sc_flags & SCF_SIGNATURE)
871 tp->t_flags |= TF_SIGNATURE;
872 #endif /* TCP_SIGNATURE */
874 tp->t_rxtsyn = sc->sc_rxtused;
875 tcp_mss(tp, sc->sc_peer_mss);
878 * Inherit some properties from the listen socket
880 ltp = intotcpcb(linp);
881 tp->t_keepinit = ltp->t_keepinit;
882 tp->t_keepidle = ltp->t_keepidle;
883 tp->t_keepintvl = ltp->t_keepintvl;
884 tp->t_keepcnt = ltp->t_keepcnt;
885 tp->t_maxidle = ltp->t_maxidle;
887 tcp_create_timermsg(tp, port);
888 tcp_callout_reset(tp, tp->tt_keep, tp->t_keepinit, tcp_timer_keep);
890 tcpstat.tcps_accepts++;
900 * This function gets called when we receive an ACK for a
901 * socket in the LISTEN state. We look up the connection
902 * in the syncache, and if its there, we pull it out of
903 * the cache and turn it into a full-blown connection in
904 * the SYN-RECEIVED state.
907 syncache_expand(struct in_conninfo *inc, struct tcphdr *th, struct socket **sop,
911 struct syncache_head *sch;
914 sc = syncache_lookup(inc, &sch);
917 * There is no syncache entry, so see if this ACK is
918 * a returning syncookie. To do this, first:
919 * A. See if this socket has had a syncache entry dropped in
920 * the past. We don't want to accept a bogus syncookie
921 * if we've never received a SYN.
922 * B. check that the syncookie is valid. If it is, then
923 * cobble up a fake syncache entry, and return.
927 sc = syncookie_lookup(inc, th, *sop);
931 tcpstat.tcps_sc_recvcookie++;
935 * If seg contains an ACK, but not for our SYN/ACK, send a RST.
937 if (th->th_ack != sc->sc_iss + 1)
940 so = syncache_socket(sc, *sop, m);
944 /* XXXjlemon check this - is this correct? */
945 tcp_respond(NULL, m, m, th,
946 th->th_seq + tlen, (tcp_seq)0, TH_RST | TH_ACK);
948 m_freem(m); /* XXX only needed for above */
949 tcpstat.tcps_sc_aborted++;
951 tcpstat.tcps_sc_completed++;
956 syncache_drop(sc, sch);
962 * Given a LISTEN socket and an inbound SYN request, add
963 * this to the syn cache, and send back a segment:
964 * <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK>
967 * IMPORTANT NOTE: We do _NOT_ ACK data that might accompany the SYN.
968 * Doing so would require that we hold onto the data and deliver it
969 * to the application. However, if we are the target of a SYN-flood
970 * DoS attack, an attacker could send data which would eventually
971 * consume all available buffer space if it were ACKed. By not ACKing
972 * the data, we avoid this DoS scenario.
975 syncache_add(struct in_conninfo *inc, struct tcpopt *to, struct tcphdr *th,
976 struct socket *so, struct mbuf *m)
978 struct tcp_syncache_percpu *syncache_percpu;
980 struct syncache *sc = NULL;
981 struct syncache_head *sch;
982 struct mbuf *ipopts = NULL;
985 syncache_percpu = &tcp_syncache_percpu[mycpu->gd_cpuid];
989 * Remember the IP options, if any.
992 if (!inc->inc_isipv6)
994 ipopts = ip_srcroute(m);
997 * See if we already have an entry for this connection.
998 * If we do, resend the SYN,ACK, and reset the retransmit timer.
1001 * The syncache should be re-initialized with the contents
1002 * of the new SYN which may have different options.
1004 sc = syncache_lookup(inc, &sch);
1006 tcpstat.tcps_sc_dupsyn++;
1009 * If we were remembering a previous source route,
1010 * forget it and use the new one we've been given.
1013 m_free(sc->sc_ipopts);
1014 sc->sc_ipopts = ipopts;
1017 * Update timestamp if present.
1019 if (sc->sc_flags & SCF_TIMESTAMP)
1020 sc->sc_tsrecent = to->to_tsval;
1022 /* Just update the TOF_SACK_PERMITTED for now. */
1023 if (tcp_do_sack && (to->to_flags & TOF_SACK_PERMITTED))
1024 sc->sc_flags |= SCF_SACK_PERMITTED;
1026 sc->sc_flags &= ~SCF_SACK_PERMITTED;
1028 /* Update initial send window */
1029 sc->sc_sndwnd = th->th_win;
1032 * PCB may have changed, pick up new values.
1035 sc->sc_inp_gencnt = tp->t_inpcb->inp_gencnt;
1036 if (syncache_respond(sc, m) == 0) {
1037 TAILQ_REMOVE(&syncache_percpu->timerq[sc->sc_rxtslot],
1039 syncache_timeout(syncache_percpu, sc, sc->sc_rxtslot);
1040 tcpstat.tcps_sndacks++;
1041 tcpstat.tcps_sndtotal++;
1047 * Fill in the syncache values.
1049 sc = kmalloc(sizeof(struct syncache), M_SYNCACHE, M_WAITOK|M_ZERO);
1050 sc->sc_inp_gencnt = tp->t_inpcb->inp_gencnt;
1051 sc->sc_ipopts = ipopts;
1052 sc->sc_inc.inc_fport = inc->inc_fport;
1053 sc->sc_inc.inc_lport = inc->inc_lport;
1056 sc->sc_inc.inc_isipv6 = inc->inc_isipv6;
1057 if (inc->inc_isipv6) {
1058 sc->sc_inc.inc6_faddr = inc->inc6_faddr;
1059 sc->sc_inc.inc6_laddr = inc->inc6_laddr;
1060 sc->sc_route6.ro_rt = NULL;
1064 sc->sc_inc.inc_faddr = inc->inc_faddr;
1065 sc->sc_inc.inc_laddr = inc->inc_laddr;
1066 sc->sc_route.ro_rt = NULL;
1068 sc->sc_irs = th->th_seq;
1070 sc->sc_peer_mss = to->to_flags & TOF_MSS ? to->to_mss : 0;
1072 sc->sc_iss = syncookie_generate(sc);
1074 sc->sc_iss = karc4random();
1076 /* Initial receive window: clip ssb_space to [0 .. TCP_MAXWIN] */
1077 win = ssb_space(&so->so_rcv);
1079 win = imin(win, TCP_MAXWIN);
1082 if (tcp_do_rfc1323) {
1084 * A timestamp received in a SYN makes
1085 * it ok to send timestamp requests and replies.
1087 if (to->to_flags & TOF_TS) {
1088 sc->sc_tsrecent = to->to_tsval;
1089 sc->sc_flags |= SCF_TIMESTAMP;
1091 if (to->to_flags & TOF_SCALE) {
1092 int wscale = TCP_MIN_WINSHIFT;
1094 /* Compute proper scaling value from buffer space */
1095 while (wscale < TCP_MAX_WINSHIFT &&
1096 (TCP_MAXWIN << wscale) < so->so_rcv.ssb_hiwat) {
1099 sc->sc_request_r_scale = wscale;
1100 sc->sc_requested_s_scale = to->to_requested_s_scale;
1101 sc->sc_flags |= SCF_WINSCALE;
1104 if (tcp_do_sack && (to->to_flags & TOF_SACK_PERMITTED))
1105 sc->sc_flags |= SCF_SACK_PERMITTED;
1106 if (tp->t_flags & TF_NOOPT)
1107 sc->sc_flags = SCF_NOOPT;
1108 #ifdef TCP_SIGNATURE
1110 * If listening socket requested TCP digests, and received SYN
1111 * contains the option, flag this in the syncache so that
1112 * syncache_respond() will do the right thing with the SYN+ACK.
1113 * XXX Currently we always record the option by default and will
1114 * attempt to use it in syncache_respond().
1116 if (to->to_flags & TOF_SIGNATURE)
1117 sc->sc_flags = SCF_SIGNATURE;
1118 #endif /* TCP_SIGNATURE */
1119 sc->sc_sndwnd = th->th_win;
1121 if (syncache_respond(sc, m) == 0) {
1122 syncache_insert(sc, sch);
1123 tcpstat.tcps_sndacks++;
1124 tcpstat.tcps_sndtotal++;
1127 tcpstat.tcps_sc_dropped++;
1133 syncache_respond(struct syncache *sc, struct mbuf *m)
1137 u_int16_t tlen, hlen, mssopt;
1138 struct ip *ip = NULL;
1141 struct ip6_hdr *ip6 = NULL;
1143 const boolean_t isipv6 = sc->sc_inc.inc_isipv6;
1145 const boolean_t isipv6 = FALSE;
1149 rt = tcp_rtlookup6(&sc->sc_inc);
1151 mssopt = rt->rt_ifp->if_mtu -
1152 (sizeof(struct ip6_hdr) + sizeof(struct tcphdr));
1154 mssopt = tcp_v6mssdflt;
1155 hlen = sizeof(struct ip6_hdr);
1157 rt = tcp_rtlookup(&sc->sc_inc);
1159 mssopt = rt->rt_ifp->if_mtu -
1160 (sizeof(struct ip) + sizeof(struct tcphdr));
1162 mssopt = tcp_mssdflt;
1163 hlen = sizeof(struct ip);
1166 /* Compute the size of the TCP options. */
1167 if (sc->sc_flags & SCF_NOOPT) {
1170 optlen = TCPOLEN_MAXSEG +
1171 ((sc->sc_flags & SCF_WINSCALE) ? 4 : 0) +
1172 ((sc->sc_flags & SCF_TIMESTAMP) ? TCPOLEN_TSTAMP_APPA : 0) +
1173 ((sc->sc_flags & SCF_SACK_PERMITTED) ?
1174 TCPOLEN_SACK_PERMITTED_ALIGNED : 0);
1175 #ifdef TCP_SIGNATURE
1176 optlen += ((sc->sc_flags & SCF_SIGNATURE) ?
1177 (TCPOLEN_SIGNATURE + 2) : 0);
1178 #endif /* TCP_SIGNATURE */
1180 tlen = hlen + sizeof(struct tcphdr) + optlen;
1184 * assume that the entire packet will fit in a header mbuf
1186 KASSERT(max_linkhdr + tlen <= MHLEN, ("syncache: mbuf too small"));
1189 * XXX shouldn't this reuse the mbuf if possible ?
1190 * Create the IP+TCP header from scratch.
1195 m = m_gethdr(MB_DONTWAIT, MT_HEADER);
1198 m->m_data += max_linkhdr;
1200 m->m_pkthdr.len = tlen;
1201 m->m_pkthdr.rcvif = NULL;
1204 ip6 = mtod(m, struct ip6_hdr *);
1205 ip6->ip6_vfc = IPV6_VERSION;
1206 ip6->ip6_nxt = IPPROTO_TCP;
1207 ip6->ip6_src = sc->sc_inc.inc6_laddr;
1208 ip6->ip6_dst = sc->sc_inc.inc6_faddr;
1209 ip6->ip6_plen = htons(tlen - hlen);
1210 /* ip6_hlim is set after checksum */
1211 /* ip6_flow = ??? */
1213 th = (struct tcphdr *)(ip6 + 1);
1215 ip = mtod(m, struct ip *);
1216 ip->ip_v = IPVERSION;
1217 ip->ip_hl = sizeof(struct ip) >> 2;
1222 ip->ip_p = IPPROTO_TCP;
1223 ip->ip_src = sc->sc_inc.inc_laddr;
1224 ip->ip_dst = sc->sc_inc.inc_faddr;
1225 ip->ip_ttl = sc->sc_tp->t_inpcb->inp_ip_ttl; /* XXX */
1226 ip->ip_tos = sc->sc_tp->t_inpcb->inp_ip_tos; /* XXX */
1229 * See if we should do MTU discovery. Route lookups are
1230 * expensive, so we will only unset the DF bit if:
1232 * 1) path_mtu_discovery is disabled
1233 * 2) the SCF_UNREACH flag has been set
1235 if (path_mtu_discovery
1236 && ((sc->sc_flags & SCF_UNREACH) == 0)) {
1237 ip->ip_off |= IP_DF;
1240 th = (struct tcphdr *)(ip + 1);
1242 th->th_sport = sc->sc_inc.inc_lport;
1243 th->th_dport = sc->sc_inc.inc_fport;
1245 th->th_seq = htonl(sc->sc_iss);
1246 th->th_ack = htonl(sc->sc_irs + 1);
1247 th->th_off = (sizeof(struct tcphdr) + optlen) >> 2;
1249 th->th_flags = TH_SYN | TH_ACK;
1250 th->th_win = htons(sc->sc_wnd);
1253 /* Tack on the TCP options. */
1256 optp = (u_int8_t *)(th + 1);
1257 *optp++ = TCPOPT_MAXSEG;
1258 *optp++ = TCPOLEN_MAXSEG;
1259 *optp++ = (mssopt >> 8) & 0xff;
1260 *optp++ = mssopt & 0xff;
1262 if (sc->sc_flags & SCF_WINSCALE) {
1263 *((u_int32_t *)optp) = htonl(TCPOPT_NOP << 24 |
1264 TCPOPT_WINDOW << 16 | TCPOLEN_WINDOW << 8 |
1265 sc->sc_request_r_scale);
1269 if (sc->sc_flags & SCF_TIMESTAMP) {
1270 u_int32_t *lp = (u_int32_t *)(optp);
1272 /* Form timestamp option as shown in appendix A of RFC 1323. */
1273 *lp++ = htonl(TCPOPT_TSTAMP_HDR);
1274 *lp++ = htonl(ticks);
1275 *lp = htonl(sc->sc_tsrecent);
1276 optp += TCPOLEN_TSTAMP_APPA;
1279 #ifdef TCP_SIGNATURE
1281 * Handle TCP-MD5 passive opener response.
1283 if (sc->sc_flags & SCF_SIGNATURE) {
1284 u_int8_t *bp = optp;
1287 *bp++ = TCPOPT_SIGNATURE;
1288 *bp++ = TCPOLEN_SIGNATURE;
1289 for (i = 0; i < TCP_SIGLEN; i++)
1291 tcpsignature_compute(m, 0, optlen,
1292 optp + 2, IPSEC_DIR_OUTBOUND);
1295 optp += TCPOLEN_SIGNATURE + 2;
1297 #endif /* TCP_SIGNATURE */
1299 if (sc->sc_flags & SCF_SACK_PERMITTED) {
1300 *((u_int32_t *)optp) = htonl(TCPOPT_SACK_PERMITTED_ALIGNED);
1301 optp += TCPOLEN_SACK_PERMITTED_ALIGNED;
1306 struct route_in6 *ro6 = &sc->sc_route6;
1309 th->th_sum = in6_cksum(m, IPPROTO_TCP, hlen, tlen - hlen);
1310 ip6->ip6_hlim = in6_selecthlim(NULL,
1311 ro6->ro_rt ? ro6->ro_rt->rt_ifp : NULL);
1312 error = ip6_output(m, NULL, ro6, 0, NULL, NULL,
1313 sc->sc_tp->t_inpcb);
1315 th->th_sum = in_pseudo(ip->ip_src.s_addr, ip->ip_dst.s_addr,
1316 htons(tlen - hlen + IPPROTO_TCP));
1317 m->m_pkthdr.csum_flags = CSUM_TCP;
1318 m->m_pkthdr.csum_data = offsetof(struct tcphdr, th_sum);
1319 m->m_pkthdr.csum_thlen = sizeof(struct tcphdr) + optlen;
1320 error = ip_output(m, sc->sc_ipopts, &sc->sc_route,
1321 IP_DEBUGROUTE, NULL, sc->sc_tp->t_inpcb);
1329 * |. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .|
1331 * | MD5(laddr,faddr,secret,lport,fport) |. . . . . . .|
1333 * (A): peer mss index
1337 * The values below are chosen to minimize the size of the tcp_secret
1338 * table, as well as providing roughly a 16 second lifetime for the cookie.
1341 #define SYNCOOKIE_WNDBITS 5 /* exposed bits for window indexing */
1342 #define SYNCOOKIE_TIMESHIFT 1 /* scale ticks to window time units */
1344 #define SYNCOOKIE_WNDMASK ((1 << SYNCOOKIE_WNDBITS) - 1)
1345 #define SYNCOOKIE_NSECRETS (1 << SYNCOOKIE_WNDBITS)
1346 #define SYNCOOKIE_TIMEOUT \
1347 (hz * (1 << SYNCOOKIE_WNDBITS) / (1 << SYNCOOKIE_TIMESHIFT))
1348 #define SYNCOOKIE_DATAMASK ((3 << SYNCOOKIE_WNDBITS) | SYNCOOKIE_WNDMASK)
1351 u_int32_t ts_secbits[4];
1353 } tcp_secret[SYNCOOKIE_NSECRETS];
1355 static int tcp_msstab[] = { 0, 536, 1460, 8960 };
1357 static MD5_CTX syn_ctx;
1359 #define MD5Add(v) MD5Update(&syn_ctx, (u_char *)&v, sizeof(v))
1362 u_int32_t laddr, faddr;
1363 u_int32_t secbits[4];
1364 u_int16_t lport, fport;
1368 CTASSERT(sizeof(struct md5_add) == 28);
1372 * Consider the problem of a recreated (and retransmitted) cookie. If the
1373 * original SYN was accepted, the connection is established. The second
1374 * SYN is inflight, and if it arrives with an ISN that falls within the
1375 * receive window, the connection is killed.
1377 * However, since cookies have other problems, this may not be worth
1382 syncookie_generate(struct syncache *sc)
1384 u_int32_t md5_buffer[4];
1389 const boolean_t isipv6 = sc->sc_inc.inc_isipv6;
1391 const boolean_t isipv6 = FALSE;
1394 idx = ((ticks << SYNCOOKIE_TIMESHIFT) / hz) & SYNCOOKIE_WNDMASK;
1395 if (tcp_secret[idx].ts_expire < ticks) {
1396 for (i = 0; i < 4; i++)
1397 tcp_secret[idx].ts_secbits[i] = karc4random();
1398 tcp_secret[idx].ts_expire = ticks + SYNCOOKIE_TIMEOUT;
1400 for (data = NELEM(tcp_msstab) - 1; data > 0; data--)
1401 if (tcp_msstab[data] <= sc->sc_peer_mss)
1403 data = (data << SYNCOOKIE_WNDBITS) | idx;
1404 data ^= sc->sc_irs; /* peer's iss */
1407 MD5Add(sc->sc_inc.inc6_laddr);
1408 MD5Add(sc->sc_inc.inc6_faddr);
1412 add.laddr = sc->sc_inc.inc_laddr.s_addr;
1413 add.faddr = sc->sc_inc.inc_faddr.s_addr;
1415 add.lport = sc->sc_inc.inc_lport;
1416 add.fport = sc->sc_inc.inc_fport;
1417 add.secbits[0] = tcp_secret[idx].ts_secbits[0];
1418 add.secbits[1] = tcp_secret[idx].ts_secbits[1];
1419 add.secbits[2] = tcp_secret[idx].ts_secbits[2];
1420 add.secbits[3] = tcp_secret[idx].ts_secbits[3];
1422 MD5Final((u_char *)&md5_buffer, &syn_ctx);
1423 data ^= (md5_buffer[0] & ~SYNCOOKIE_WNDMASK);
1427 static struct syncache *
1428 syncookie_lookup(struct in_conninfo *inc, struct tcphdr *th, struct socket *so)
1430 u_int32_t md5_buffer[4];
1431 struct syncache *sc;
1436 data = (th->th_ack - 1) ^ (th->th_seq - 1); /* remove ISS */
1437 idx = data & SYNCOOKIE_WNDMASK;
1438 if (tcp_secret[idx].ts_expire < ticks ||
1439 sototcpcb(so)->ts_recent + SYNCOOKIE_TIMEOUT < ticks)
1443 if (inc->inc_isipv6) {
1444 MD5Add(inc->inc6_laddr);
1445 MD5Add(inc->inc6_faddr);
1451 add.laddr = inc->inc_laddr.s_addr;
1452 add.faddr = inc->inc_faddr.s_addr;
1454 add.lport = inc->inc_lport;
1455 add.fport = inc->inc_fport;
1456 add.secbits[0] = tcp_secret[idx].ts_secbits[0];
1457 add.secbits[1] = tcp_secret[idx].ts_secbits[1];
1458 add.secbits[2] = tcp_secret[idx].ts_secbits[2];
1459 add.secbits[3] = tcp_secret[idx].ts_secbits[3];
1461 MD5Final((u_char *)&md5_buffer, &syn_ctx);
1462 data ^= md5_buffer[0];
1463 if (data & ~SYNCOOKIE_DATAMASK)
1465 data = data >> SYNCOOKIE_WNDBITS;
1468 * Fill in the syncache values.
1469 * XXX duplicate code from syncache_add
1471 sc = kmalloc(sizeof(struct syncache), M_SYNCACHE, M_WAITOK|M_ZERO);
1472 sc->sc_ipopts = NULL;
1473 sc->sc_inc.inc_fport = inc->inc_fport;
1474 sc->sc_inc.inc_lport = inc->inc_lport;
1476 sc->sc_inc.inc_isipv6 = inc->inc_isipv6;
1477 if (inc->inc_isipv6) {
1478 sc->sc_inc.inc6_faddr = inc->inc6_faddr;
1479 sc->sc_inc.inc6_laddr = inc->inc6_laddr;
1480 sc->sc_route6.ro_rt = NULL;
1484 sc->sc_inc.inc_faddr = inc->inc_faddr;
1485 sc->sc_inc.inc_laddr = inc->inc_laddr;
1486 sc->sc_route.ro_rt = NULL;
1488 sc->sc_irs = th->th_seq - 1;
1489 sc->sc_iss = th->th_ack - 1;
1490 wnd = ssb_space(&so->so_rcv);
1492 wnd = imin(wnd, TCP_MAXWIN);
1496 sc->sc_peer_mss = tcp_msstab[data];