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NetBSD/sys/netinet/tcp_input.c
ragge da20a11a23 Fix the bug in the tcp transmit prediction code. 
During testing the prediction counters show a hit-rate on about 85% for
packets sent on a local LAN, and better than 99% for intercontinental
high-speed bulk traffic (!).
2003-10-24 10:25:40 +00:00

3833 lines
99 KiB
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/* $NetBSD: tcp_input.c,v 1.186 2003/10/24 10:25:40 ragge Exp $ */
/*
* Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the project nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* @(#)COPYRIGHT 1.1 (NRL) 17 January 1995
*
* NRL grants permission for redistribution and use in source and binary
* forms, with or without modification, of the software and documentation
* created at NRL provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgements:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* This product includes software developed at the Information
* Technology Division, US Naval Research Laboratory.
* 4. Neither the name of the NRL nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THE SOFTWARE PROVIDED BY NRL IS PROVIDED BY NRL AND CONTRIBUTORS ``AS
* IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL NRL OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* The views and conclusions contained in the software and documentation
* are those of the authors and should not be interpreted as representing
* official policies, either expressed or implied, of the US Naval
* Research Laboratory (NRL).
*/
/*-
* Copyright (c) 1997, 1998, 1999, 2001 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Jason R. Thorpe and Kevin M. Lahey of the Numerical Aerospace Simulation
* Facility, NASA Ames Research Center.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the NetBSD
* Foundation, Inc. and its contributors.
* 4. Neither the name of The NetBSD Foundation nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/*
* Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)tcp_input.c 8.12 (Berkeley) 5/24/95
*/
/*
* TODO list for SYN cache stuff:
*
* Find room for a "state" field, which is needed to keep a
* compressed state for TIME_WAIT TCBs. It's been noted already
* that this is fairly important for very high-volume web and
* mail servers, which use a large number of short-lived
* connections.
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: tcp_input.c,v 1.186 2003/10/24 10:25:40 ragge Exp $");
#include "opt_inet.h"
#include "opt_ipsec.h"
#include "opt_inet_csum.h"
#include "opt_tcp_debug.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/errno.h>
#include <sys/syslog.h>
#include <sys/pool.h>
#include <sys/domain.h>
#include <sys/kernel.h>
#include <net/if.h>
#include <net/route.h>
#include <net/if_types.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/in_pcb.h>
#include <netinet/in_var.h>
#include <netinet/ip_var.h>
#ifdef INET6
#ifndef INET
#include <netinet/in.h>
#endif
#include <netinet/ip6.h>
#include <netinet6/ip6_var.h>
#include <netinet6/in6_pcb.h>
#include <netinet6/ip6_var.h>
#include <netinet6/in6_var.h>
#include <netinet/icmp6.h>
#include <netinet6/nd6.h>
#endif
#ifndef INET6
/* always need ip6.h for IP6_EXTHDR_GET */
#include <netinet/ip6.h>
#endif
#include <netinet/tcp.h>
#include <netinet/tcp_fsm.h>
#include <netinet/tcp_seq.h>
#include <netinet/tcp_timer.h>
#include <netinet/tcp_var.h>
#include <netinet/tcpip.h>
#include <netinet/tcp_debug.h>
#include <machine/stdarg.h>
#ifdef IPSEC
#include <netinet6/ipsec.h>
#include <netkey/key.h>
#endif /*IPSEC*/
#ifdef INET6
#include "faith.h"
#if defined(NFAITH) && NFAITH > 0
#include <net/if_faith.h>
#endif
#endif /* IPSEC */
#ifdef FAST_IPSEC
#include <netipsec/ipsec.h>
#include <netipsec/key.h>
#endif /* FAST_IPSEC*/
int tcprexmtthresh = 3;
int tcp_log_refused;
static int tcp_rst_ppslim_count = 0;
static struct timeval tcp_rst_ppslim_last;
#define TCP_PAWS_IDLE (24 * 24 * 60 * 60 * PR_SLOWHZ)
/* for modulo comparisons of timestamps */
#define TSTMP_LT(a,b) ((int)((a)-(b)) < 0)
#define TSTMP_GEQ(a,b) ((int)((a)-(b)) >= 0)
/*
* Neighbor Discovery, Neighbor Unreachability Detection Upper layer hint.
*/
#ifdef INET6
#define ND6_HINT(tp) \
do { \
if (tp && tp->t_in6pcb && tp->t_family == AF_INET6 \
&& tp->t_in6pcb->in6p_route.ro_rt) { \
nd6_nud_hint(tp->t_in6pcb->in6p_route.ro_rt, NULL, 0); \
} \
} while (/*CONSTCOND*/ 0)
#else
#define ND6_HINT(tp)
#endif
/*
* Macro to compute ACK transmission behavior. Delay the ACK unless
* we have already delayed an ACK (must send an ACK every two segments).
* We also ACK immediately if we received a PUSH and the ACK-on-PUSH
* option is enabled.
*/
#define TCP_SETUP_ACK(tp, th) \
do { \
if ((tp)->t_flags & TF_DELACK || \
(tcp_ack_on_push && (th)->th_flags & TH_PUSH)) \
tp->t_flags |= TF_ACKNOW; \
else \
TCP_SET_DELACK(tp); \
} while (/*CONSTCOND*/ 0)
/*
* Convert TCP protocol fields to host order for easier processing.
*/
#define TCP_FIELDS_TO_HOST(th) \
do { \
NTOHL((th)->th_seq); \
NTOHL((th)->th_ack); \
NTOHS((th)->th_win); \
NTOHS((th)->th_urp); \
} while (/*CONSTCOND*/ 0)
/*
* ... and reverse the above.
*/
#define TCP_FIELDS_TO_NET(th) \
do { \
HTONL((th)->th_seq); \
HTONL((th)->th_ack); \
HTONS((th)->th_win); \
HTONS((th)->th_urp); \
} while (/*CONSTCOND*/ 0)
#ifdef TCP_CSUM_COUNTERS
#include <sys/device.h>
extern struct evcnt tcp_hwcsum_ok;
extern struct evcnt tcp_hwcsum_bad;
extern struct evcnt tcp_hwcsum_data;
extern struct evcnt tcp_swcsum;
#define TCP_CSUM_COUNTER_INCR(ev) (ev)->ev_count++
#else
#define TCP_CSUM_COUNTER_INCR(ev) /* nothing */
#endif /* TCP_CSUM_COUNTERS */
#ifdef TCP_REASS_COUNTERS
#include <sys/device.h>
extern struct evcnt tcp_reass_;
extern struct evcnt tcp_reass_empty;
extern struct evcnt tcp_reass_iteration[8];
extern struct evcnt tcp_reass_prependfirst;
extern struct evcnt tcp_reass_prepend;
extern struct evcnt tcp_reass_insert;
extern struct evcnt tcp_reass_inserttail;
extern struct evcnt tcp_reass_append;
extern struct evcnt tcp_reass_appendtail;
extern struct evcnt tcp_reass_overlaptail;
extern struct evcnt tcp_reass_overlapfront;
extern struct evcnt tcp_reass_segdup;
extern struct evcnt tcp_reass_fragdup;
#define TCP_REASS_COUNTER_INCR(ev) (ev)->ev_count++
#else
#define TCP_REASS_COUNTER_INCR(ev) /* nothing */
#endif /* TCP_REASS_COUNTERS */
#ifdef INET
static void tcp4_log_refused __P((const struct ip *, const struct tcphdr *));
#endif
#ifdef INET6
static void tcp6_log_refused
__P((const struct ip6_hdr *, const struct tcphdr *));
#endif
int
tcp_reass(tp, th, m, tlen)
struct tcpcb *tp;
struct tcphdr *th;
struct mbuf *m;
int *tlen;
{
struct ipqent *p, *q, *nq, *tiqe = NULL;
struct socket *so = NULL;
int pkt_flags;
tcp_seq pkt_seq;
unsigned pkt_len;
u_long rcvpartdupbyte = 0;
u_long rcvoobyte;
#ifdef TCP_REASS_COUNTERS
u_int count = 0;
#endif
if (tp->t_inpcb)
so = tp->t_inpcb->inp_socket;
#ifdef INET6
else if (tp->t_in6pcb)
so = tp->t_in6pcb->in6p_socket;
#endif
TCP_REASS_LOCK_CHECK(tp);
/*
* Call with th==0 after become established to
* force pre-ESTABLISHED data up to user socket.
*/
if (th == 0)
goto present;
rcvoobyte = *tlen;
/*
* Copy these to local variables because the tcpiphdr
* gets munged while we are collapsing mbufs.
*/
pkt_seq = th->th_seq;
pkt_len = *tlen;
pkt_flags = th->th_flags;
TCP_REASS_COUNTER_INCR(&tcp_reass_);
if ((p = TAILQ_LAST(&tp->segq, ipqehead)) != NULL) {
/*
* When we miss a packet, the vast majority of time we get
* packets that follow it in order. So optimize for that.
*/
if (pkt_seq == p->ipqe_seq + p->ipqe_len) {
p->ipqe_len += pkt_len;
p->ipqe_flags |= pkt_flags;
m_cat(p->ipqe_m, m);
tiqe = p;
TAILQ_REMOVE(&tp->timeq, p, ipqe_timeq);
TCP_REASS_COUNTER_INCR(&tcp_reass_appendtail);
goto skip_replacement;
}
/*
* While we're here, if the pkt is completely beyond
* anything we have, just insert it at the tail.
*/
if (SEQ_GT(pkt_seq, p->ipqe_seq + p->ipqe_len)) {
TCP_REASS_COUNTER_INCR(&tcp_reass_inserttail);
goto insert_it;
}
}
q = TAILQ_FIRST(&tp->segq);
if (q != NULL) {
/*
* If this segment immediately precedes the first out-of-order
* block, simply slap the segment in front of it and (mostly)
* skip the complicated logic.
*/
if (pkt_seq + pkt_len == q->ipqe_seq) {
q->ipqe_seq = pkt_seq;
q->ipqe_len += pkt_len;
q->ipqe_flags |= pkt_flags;
m_cat(m, q->ipqe_m);
q->ipqe_m = m;
tiqe = q;
TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq);
TCP_REASS_COUNTER_INCR(&tcp_reass_prependfirst);
goto skip_replacement;
}
} else {
TCP_REASS_COUNTER_INCR(&tcp_reass_empty);
}
/*
* Find a segment which begins after this one does.
*/
for (p = NULL; q != NULL; q = nq) {
nq = TAILQ_NEXT(q, ipqe_q);
#ifdef TCP_REASS_COUNTERS
count++;
#endif
/*
* If the received segment is just right after this
* fragment, merge the two together and then check
* for further overlaps.
*/
if (q->ipqe_seq + q->ipqe_len == pkt_seq) {
#ifdef TCPREASS_DEBUG
printf("tcp_reass[%p]: concat %u:%u(%u) to %u:%u(%u)\n",
tp, pkt_seq, pkt_seq + pkt_len, pkt_len,
q->ipqe_seq, q->ipqe_seq + q->ipqe_len, q->ipqe_len);
#endif
pkt_len += q->ipqe_len;
pkt_flags |= q->ipqe_flags;
pkt_seq = q->ipqe_seq;
m_cat(q->ipqe_m, m);
m = q->ipqe_m;
TCP_REASS_COUNTER_INCR(&tcp_reass_append);
goto free_ipqe;
}
/*
* If the received segment is completely past this
* fragment, we need to go the next fragment.
*/
if (SEQ_LT(q->ipqe_seq + q->ipqe_len, pkt_seq)) {
p = q;
continue;
}
/*
* If the fragment is past the received segment,
* it (or any following) can't be concatenated.
*/
if (SEQ_GT(q->ipqe_seq, pkt_seq + pkt_len)) {
TCP_REASS_COUNTER_INCR(&tcp_reass_insert);
break;
}
/*
* We've received all the data in this segment before.
* mark it as a duplicate and return.
*/
if (SEQ_LEQ(q->ipqe_seq, pkt_seq) &&
SEQ_GEQ(q->ipqe_seq + q->ipqe_len, pkt_seq + pkt_len)) {
tcpstat.tcps_rcvduppack++;
tcpstat.tcps_rcvdupbyte += pkt_len;
m_freem(m);
if (tiqe != NULL)
pool_put(&ipqent_pool, tiqe);
TCP_REASS_COUNTER_INCR(&tcp_reass_segdup);
return (0);
}
/*
* Received segment completely overlaps this fragment
* so we drop the fragment (this keeps the temporal
* ordering of segments correct).
*/
if (SEQ_GEQ(q->ipqe_seq, pkt_seq) &&
SEQ_LEQ(q->ipqe_seq + q->ipqe_len, pkt_seq + pkt_len)) {
rcvpartdupbyte += q->ipqe_len;
m_freem(q->ipqe_m);
TCP_REASS_COUNTER_INCR(&tcp_reass_fragdup);
goto free_ipqe;
}
/*
* RX'ed segment extends past the end of the
* fragment. Drop the overlapping bytes. Then
* merge the fragment and segment then treat as
* a longer received packet.
*/
if (SEQ_LT(q->ipqe_seq, pkt_seq)
&& SEQ_GT(q->ipqe_seq + q->ipqe_len, pkt_seq)) {
int overlap = q->ipqe_seq + q->ipqe_len - pkt_seq;
#ifdef TCPREASS_DEBUG
printf("tcp_reass[%p]: trim starting %d bytes of %u:%u(%u)\n",
tp, overlap,
pkt_seq, pkt_seq + pkt_len, pkt_len);
#endif
m_adj(m, overlap);
rcvpartdupbyte += overlap;
m_cat(q->ipqe_m, m);
m = q->ipqe_m;
pkt_seq = q->ipqe_seq;
pkt_len += q->ipqe_len - overlap;
rcvoobyte -= overlap;
TCP_REASS_COUNTER_INCR(&tcp_reass_overlaptail);
goto free_ipqe;
}
/*
* RX'ed segment extends past the front of the
* fragment. Drop the overlapping bytes on the
* received packet. The packet will then be
* contatentated with this fragment a bit later.
*/
if (SEQ_GT(q->ipqe_seq, pkt_seq)
&& SEQ_LT(q->ipqe_seq, pkt_seq + pkt_len)) {
int overlap = pkt_seq + pkt_len - q->ipqe_seq;
#ifdef TCPREASS_DEBUG
printf("tcp_reass[%p]: trim trailing %d bytes of %u:%u(%u)\n",
tp, overlap,
pkt_seq, pkt_seq + pkt_len, pkt_len);
#endif
m_adj(m, -overlap);
pkt_len -= overlap;
rcvpartdupbyte += overlap;
TCP_REASS_COUNTER_INCR(&tcp_reass_overlapfront);
rcvoobyte -= overlap;
}
/*
* If the received segment immediates precedes this
* fragment then tack the fragment onto this segment
* and reinsert the data.
*/
if (q->ipqe_seq == pkt_seq + pkt_len) {
#ifdef TCPREASS_DEBUG
printf("tcp_reass[%p]: append %u:%u(%u) to %u:%u(%u)\n",
tp, q->ipqe_seq, q->ipqe_seq + q->ipqe_len, q->ipqe_len,
pkt_seq, pkt_seq + pkt_len, pkt_len);
#endif
pkt_len += q->ipqe_len;
pkt_flags |= q->ipqe_flags;
m_cat(m, q->ipqe_m);
TAILQ_REMOVE(&tp->segq, q, ipqe_q);
TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq);
if (tiqe == NULL) {
tiqe = q;
} else {
pool_put(&ipqent_pool, q);
}
TCP_REASS_COUNTER_INCR(&tcp_reass_prepend);
break;
}
/*
* If the fragment is before the segment, remember it.
* When this loop is terminated, p will contain the
* pointer to fragment that is right before the received
* segment.
*/
if (SEQ_LEQ(q->ipqe_seq, pkt_seq))
p = q;
continue;
/*
* This is a common operation. It also will allow
* to save doing a malloc/free in most instances.
*/
free_ipqe:
TAILQ_REMOVE(&tp->segq, q, ipqe_q);
TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq);
if (tiqe == NULL) {
tiqe = q;
} else {
pool_put(&ipqent_pool, q);
}
}
#ifdef TCP_REASS_COUNTERS
if (count > 7)
TCP_REASS_COUNTER_INCR(&tcp_reass_iteration[0]);
else if (count > 0)
TCP_REASS_COUNTER_INCR(&tcp_reass_iteration[count]);
#endif
insert_it:
/*
* Allocate a new queue entry since the received segment did not
* collapse onto any other out-of-order block; thus we are allocating
* a new block. If it had collapsed, tiqe would not be NULL and
* we would be reusing it.
* XXX If we can't, just drop the packet. XXX
*/
if (tiqe == NULL) {
tiqe = pool_get(&ipqent_pool, PR_NOWAIT);
if (tiqe == NULL) {
tcpstat.tcps_rcvmemdrop++;
m_freem(m);
return (0);
}
}
/*
* Update the counters.
*/
tcpstat.tcps_rcvoopack++;
tcpstat.tcps_rcvoobyte += rcvoobyte;
if (rcvpartdupbyte) {
tcpstat.tcps_rcvpartduppack++;
tcpstat.tcps_rcvpartdupbyte += rcvpartdupbyte;
}
/*
* Insert the new fragment queue entry into both queues.
*/
tiqe->ipqe_m = m;
tiqe->ipqe_seq = pkt_seq;
tiqe->ipqe_len = pkt_len;
tiqe->ipqe_flags = pkt_flags;
if (p == NULL) {
TAILQ_INSERT_HEAD(&tp->segq, tiqe, ipqe_q);
#ifdef TCPREASS_DEBUG
if (tiqe->ipqe_seq != tp->rcv_nxt)
printf("tcp_reass[%p]: insert %u:%u(%u) at front\n",
tp, pkt_seq, pkt_seq + pkt_len, pkt_len);
#endif
} else {
TAILQ_INSERT_AFTER(&tp->segq, p, tiqe, ipqe_q);
#ifdef TCPREASS_DEBUG
printf("tcp_reass[%p]: insert %u:%u(%u) after %u:%u(%u)\n",
tp, pkt_seq, pkt_seq + pkt_len, pkt_len,
p->ipqe_seq, p->ipqe_seq + p->ipqe_len, p->ipqe_len);
#endif
}
skip_replacement:
TAILQ_INSERT_HEAD(&tp->timeq, tiqe, ipqe_timeq);
present:
/*
* Present data to user, advancing rcv_nxt through
* completed sequence space.
*/
if (TCPS_HAVEESTABLISHED(tp->t_state) == 0)
return (0);
q = TAILQ_FIRST(&tp->segq);
if (q == NULL || q->ipqe_seq != tp->rcv_nxt)
return (0);
if (tp->t_state == TCPS_SYN_RECEIVED && q->ipqe_len)
return (0);
tp->rcv_nxt += q->ipqe_len;
pkt_flags = q->ipqe_flags & TH_FIN;
ND6_HINT(tp);
TAILQ_REMOVE(&tp->segq, q, ipqe_q);
TAILQ_REMOVE(&tp->timeq, q, ipqe_timeq);
if (so->so_state & SS_CANTRCVMORE)
m_freem(q->ipqe_m);
else
sbappendstream(&so->so_rcv, q->ipqe_m);
pool_put(&ipqent_pool, q);
sorwakeup(so);
return (pkt_flags);
}
#ifdef INET6
int
tcp6_input(mp, offp, proto)
struct mbuf **mp;
int *offp, proto;
{
struct mbuf *m = *mp;
/*
* draft-itojun-ipv6-tcp-to-anycast
* better place to put this in?
*/
if (m->m_flags & M_ANYCAST6) {
struct ip6_hdr *ip6;
if (m->m_len < sizeof(struct ip6_hdr)) {
if ((m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) {
tcpstat.tcps_rcvshort++;
return IPPROTO_DONE;
}
}
ip6 = mtod(m, struct ip6_hdr *);
icmp6_error(m, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR,
(caddr_t)&ip6->ip6_dst - (caddr_t)ip6);
return IPPROTO_DONE;
}
tcp_input(m, *offp, proto);
return IPPROTO_DONE;
}
#endif
#ifdef INET
static void
tcp4_log_refused(ip, th)
const struct ip *ip;
const struct tcphdr *th;
{
char src[4*sizeof "123"];
char dst[4*sizeof "123"];
if (ip) {
strlcpy(src, inet_ntoa(ip->ip_src), sizeof(src));
strlcpy(dst, inet_ntoa(ip->ip_dst), sizeof(dst));
}
else {
strlcpy(src, "(unknown)", sizeof(src));
strlcpy(dst, "(unknown)", sizeof(dst));
}
log(LOG_INFO,
"Connection attempt to TCP %s:%d from %s:%d\n",
dst, ntohs(th->th_dport),
src, ntohs(th->th_sport));
}
#endif
#ifdef INET6
static void
tcp6_log_refused(ip6, th)
const struct ip6_hdr *ip6;
const struct tcphdr *th;
{
char src[INET6_ADDRSTRLEN];
char dst[INET6_ADDRSTRLEN];
if (ip6) {
strlcpy(src, ip6_sprintf(&ip6->ip6_src), sizeof(src));
strlcpy(dst, ip6_sprintf(&ip6->ip6_dst), sizeof(dst));
}
else {
strlcpy(src, "(unknown v6)", sizeof(src));
strlcpy(dst, "(unknown v6)", sizeof(dst));
}
log(LOG_INFO,
"Connection attempt to TCP [%s]:%d from [%s]:%d\n",
dst, ntohs(th->th_dport),
src, ntohs(th->th_sport));
}
#endif
/*
* TCP input routine, follows pages 65-76 of the
* protocol specification dated September, 1981 very closely.
*/
void
#if __STDC__
tcp_input(struct mbuf *m, ...)
#else
tcp_input(m, va_alist)
struct mbuf *m;
#endif
{
struct tcphdr *th;
struct ip *ip;
struct inpcb *inp;
#ifdef INET6
struct ip6_hdr *ip6;
struct in6pcb *in6p;
#endif
u_int8_t *optp = NULL;
int optlen = 0;
int len, tlen, toff, hdroptlen = 0;
struct tcpcb *tp = 0;
int tiflags;
struct socket *so = NULL;
int todrop, acked, ourfinisacked, needoutput = 0;
#ifdef TCP_DEBUG
short ostate = 0;
#endif
int iss = 0;
u_long tiwin;
struct tcp_opt_info opti;
int off, iphlen;
va_list ap;
int af; /* af on the wire */
struct mbuf *tcp_saveti = NULL;
MCLAIM(m, &tcp_rx_mowner);
va_start(ap, m);
toff = va_arg(ap, int);
(void)va_arg(ap, int); /* ignore value, advance ap */
va_end(ap);
tcpstat.tcps_rcvtotal++;
bzero(&opti, sizeof(opti));
opti.ts_present = 0;
opti.maxseg = 0;
/*
* RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN.
*
* TCP is, by definition, unicast, so we reject all
* multicast outright.
*
* Note, there are additional src/dst address checks in
* the AF-specific code below.
*/
if (m->m_flags & (M_BCAST|M_MCAST)) {
/* XXX stat */
goto drop;
}
#ifdef INET6
if (m->m_flags & M_ANYCAST6) {
/* XXX stat */
goto drop;
}
#endif
/*
* Get IP and TCP header together in first mbuf.
* Note: IP leaves IP header in first mbuf.
*/
ip = mtod(m, struct ip *);
#ifdef INET6
ip6 = NULL;
#endif
switch (ip->ip_v) {
#ifdef INET
case 4:
af = AF_INET;
iphlen = sizeof(struct ip);
ip = mtod(m, struct ip *);
IP6_EXTHDR_GET(th, struct tcphdr *, m, toff,
sizeof(struct tcphdr));
if (th == NULL) {
tcpstat.tcps_rcvshort++;
return;
}
/* We do the checksum after PCB lookup... */
len = ntohs(ip->ip_len);
tlen = len - toff;
break;
#endif
#ifdef INET6
case 6:
ip = NULL;
iphlen = sizeof(struct ip6_hdr);
af = AF_INET6;
ip6 = mtod(m, struct ip6_hdr *);
IP6_EXTHDR_GET(th, struct tcphdr *, m, toff,
sizeof(struct tcphdr));
if (th == NULL) {
tcpstat.tcps_rcvshort++;
return;
}
/* Be proactive about malicious use of IPv4 mapped address */
if (IN6_IS_ADDR_V4MAPPED(&ip6->ip6_src) ||
IN6_IS_ADDR_V4MAPPED(&ip6->ip6_dst)) {
/* XXX stat */
goto drop;
}
/*
* Be proactive about unspecified IPv6 address in source.
* As we use all-zero to indicate unbounded/unconnected pcb,
* unspecified IPv6 address can be used to confuse us.
*
* Note that packets with unspecified IPv6 destination is
* already dropped in ip6_input.
*/
if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src)) {
/* XXX stat */
goto drop;
}
/*
* Make sure destination address is not multicast.
* Source address checked in ip6_input().
*/
if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
/* XXX stat */
goto drop;
}
/* We do the checksum after PCB lookup... */
len = m->m_pkthdr.len;
tlen = len - toff;
break;
#endif
default:
m_freem(m);
return;
}
KASSERT(TCP_HDR_ALIGNED_P(th));
/*
* Check that TCP offset makes sense,
* pull out TCP options and adjust length. XXX
*/
off = th->th_off << 2;
if (off < sizeof (struct tcphdr) || off > tlen) {
tcpstat.tcps_rcvbadoff++;
goto drop;
}
tlen -= off;
/*
* tcp_input() has been modified to use tlen to mean the TCP data
* length throughout the function. Other functions can use
* m->m_pkthdr.len as the basis for calculating the TCP data length.
* rja
*/
if (off > sizeof (struct tcphdr)) {
IP6_EXTHDR_GET(th, struct tcphdr *, m, toff, off);
if (th == NULL) {
tcpstat.tcps_rcvshort++;
return;
}
/*
* NOTE: ip/ip6 will not be affected by m_pulldown()
* (as they're before toff) and we don't need to update those.
*/
KASSERT(TCP_HDR_ALIGNED_P(th));
optlen = off - sizeof (struct tcphdr);
optp = ((u_int8_t *)th) + sizeof(struct tcphdr);
/*
* Do quick retrieval of timestamp options ("options
* prediction?"). If timestamp is the only option and it's
* formatted as recommended in RFC 1323 appendix A, we
* quickly get the values now and not bother calling
* tcp_dooptions(), etc.
*/
if ((optlen == TCPOLEN_TSTAMP_APPA ||
(optlen > TCPOLEN_TSTAMP_APPA &&
optp[TCPOLEN_TSTAMP_APPA] == TCPOPT_EOL)) &&
*(u_int32_t *)optp == htonl(TCPOPT_TSTAMP_HDR) &&
(th->th_flags & TH_SYN) == 0) {
opti.ts_present = 1;
opti.ts_val = ntohl(*(u_int32_t *)(optp + 4));
opti.ts_ecr = ntohl(*(u_int32_t *)(optp + 8));
optp = NULL; /* we've parsed the options */
}
}
tiflags = th->th_flags;
/*
* Locate pcb for segment.
*/
findpcb:
inp = NULL;
#ifdef INET6
in6p = NULL;
#endif
switch (af) {
#ifdef INET
case AF_INET:
inp = in_pcblookup_connect(&tcbtable, ip->ip_src, th->th_sport,
ip->ip_dst, th->th_dport);
if (inp == 0) {
++tcpstat.tcps_pcbhashmiss;
inp = in_pcblookup_bind(&tcbtable, ip->ip_dst, th->th_dport);
}
#ifdef INET6
if (inp == 0) {
struct in6_addr s, d;
/* mapped addr case */
bzero(&s, sizeof(s));
s.s6_addr16[5] = htons(0xffff);
bcopy(&ip->ip_src, &s.s6_addr32[3], sizeof(ip->ip_src));
bzero(&d, sizeof(d));
d.s6_addr16[5] = htons(0xffff);
bcopy(&ip->ip_dst, &d.s6_addr32[3], sizeof(ip->ip_dst));
in6p = in6_pcblookup_connect(&tcbtable, &s,
th->th_sport, &d, th->th_dport, 0);
if (in6p == 0) {
++tcpstat.tcps_pcbhashmiss;
in6p = in6_pcblookup_bind(&tcbtable, &d,
th->th_dport, 0);
}
}
#endif
#ifndef INET6
if (inp == 0)
#else
if (inp == 0 && in6p == 0)
#endif
{
++tcpstat.tcps_noport;
if (tcp_log_refused &&
(tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) {
tcp4_log_refused(ip, th);
}
TCP_FIELDS_TO_HOST(th);
goto dropwithreset_ratelim;
}
#if defined(IPSEC) || defined(FAST_IPSEC)
if (inp && (inp->inp_socket->so_options & SO_ACCEPTCONN) == 0 &&
ipsec4_in_reject(m, inp)) {
ipsecstat.in_polvio++;
goto drop;
}
#ifdef INET6
else if (in6p &&
(in6p->in6p_socket->so_options & SO_ACCEPTCONN) == 0 &&
ipsec4_in_reject_so(m, in6p->in6p_socket)) {
ipsecstat.in_polvio++;
goto drop;
}
#endif
#endif /*IPSEC*/
break;
#endif /*INET*/
#ifdef INET6
case AF_INET6:
{
int faith;
#if defined(NFAITH) && NFAITH > 0
faith = faithprefix(&ip6->ip6_dst);
#else
faith = 0;
#endif
in6p = in6_pcblookup_connect(&tcbtable, &ip6->ip6_src,
th->th_sport, &ip6->ip6_dst, th->th_dport, faith);
if (in6p == NULL) {
++tcpstat.tcps_pcbhashmiss;
in6p = in6_pcblookup_bind(&tcbtable, &ip6->ip6_dst,
th->th_dport, faith);
}
if (in6p == NULL) {
++tcpstat.tcps_noport;
if (tcp_log_refused &&
(tiflags & (TH_RST|TH_ACK|TH_SYN)) == TH_SYN) {
tcp6_log_refused(ip6, th);
}
TCP_FIELDS_TO_HOST(th);
goto dropwithreset_ratelim;
}
#if defined(IPSEC) || defined(FAST_IPSEC)
if ((in6p->in6p_socket->so_options & SO_ACCEPTCONN) == 0 &&
ipsec6_in_reject(m, in6p)) {
ipsec6stat.in_polvio++;
goto drop;
}
#endif /*IPSEC*/
break;
}
#endif
}
/*
* If the state is CLOSED (i.e., TCB does not exist) then
* all data in the incoming segment is discarded.
* If the TCB exists but is in CLOSED state, it is embryonic,
* but should either do a listen or a connect soon.
*/
tp = NULL;
so = NULL;
if (inp) {
tp = intotcpcb(inp);
so = inp->inp_socket;
}
#ifdef INET6
else if (in6p) {
tp = in6totcpcb(in6p);
so = in6p->in6p_socket;
}
#endif
if (tp == 0) {
TCP_FIELDS_TO_HOST(th);
goto dropwithreset_ratelim;
}
if (tp->t_state == TCPS_CLOSED)
goto drop;
/*
* Checksum extended TCP header and data.
*/
switch (af) {
#ifdef INET
case AF_INET:
switch (m->m_pkthdr.csum_flags &
((m->m_pkthdr.rcvif->if_csum_flags_rx & M_CSUM_TCPv4) |
M_CSUM_TCP_UDP_BAD | M_CSUM_DATA)) {
case M_CSUM_TCPv4|M_CSUM_TCP_UDP_BAD:
TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_bad);
goto badcsum;
case M_CSUM_TCPv4|M_CSUM_DATA: {
u_int32_t hw_csum = m->m_pkthdr.csum_data;
TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_data);
if (m->m_pkthdr.csum_flags & M_CSUM_NO_PSEUDOHDR) {
hw_csum = in_cksum_phdr(ip->ip_src.s_addr,
ip->ip_dst.s_addr,
htonl(hw_csum + ntohs(ip->ip_len) +
IPPROTO_UDP));
}
if ((hw_csum ^ 0xffff) != 0)
goto badcsum;
break;
}
case M_CSUM_TCPv4:
/* Checksum was okay. */
TCP_CSUM_COUNTER_INCR(&tcp_hwcsum_ok);
break;
default:
/* Must compute it ourselves. */
TCP_CSUM_COUNTER_INCR(&tcp_swcsum);
if (in4_cksum(m, IPPROTO_TCP, toff, tlen + off) != 0)
goto badcsum;
break;
}
break;
#endif /* INET4 */
#ifdef INET6
case AF_INET6:
if (in6_cksum(m, IPPROTO_TCP, toff, tlen + off) != 0)
goto badcsum;
break;
#endif /* INET6 */
}
TCP_FIELDS_TO_HOST(th);
/* Unscale the window into a 32-bit value. */
if ((tiflags & TH_SYN) == 0)
tiwin = th->th_win << tp->snd_scale;
else
tiwin = th->th_win;
#ifdef INET6
/* save packet options if user wanted */
if (in6p && (in6p->in6p_flags & IN6P_CONTROLOPTS)) {
if (in6p->in6p_options) {
m_freem(in6p->in6p_options);
in6p->in6p_options = 0;
}
ip6_savecontrol(in6p, &in6p->in6p_options, ip6, m);
}
#endif
if (so->so_options & (SO_DEBUG|SO_ACCEPTCONN)) {
union syn_cache_sa src;
union syn_cache_sa dst;
bzero(&src, sizeof(src));
bzero(&dst, sizeof(dst));
switch (af) {
#ifdef INET
case AF_INET:
src.sin.sin_len = sizeof(struct sockaddr_in);
src.sin.sin_family = AF_INET;
src.sin.sin_addr = ip->ip_src;
src.sin.sin_port = th->th_sport;
dst.sin.sin_len = sizeof(struct sockaddr_in);
dst.sin.sin_family = AF_INET;
dst.sin.sin_addr = ip->ip_dst;
dst.sin.sin_port = th->th_dport;
break;
#endif
#ifdef INET6
case AF_INET6:
src.sin6.sin6_len = sizeof(struct sockaddr_in6);
src.sin6.sin6_family = AF_INET6;
src.sin6.sin6_addr = ip6->ip6_src;
src.sin6.sin6_port = th->th_sport;
dst.sin6.sin6_len = sizeof(struct sockaddr_in6);
dst.sin6.sin6_family = AF_INET6;
dst.sin6.sin6_addr = ip6->ip6_dst;
dst.sin6.sin6_port = th->th_dport;
break;
#endif /* INET6 */
default:
goto badsyn; /*sanity*/
}
if (so->so_options & SO_DEBUG) {
#ifdef TCP_DEBUG
ostate = tp->t_state;
#endif
tcp_saveti = NULL;
if (iphlen + sizeof(struct tcphdr) > MHLEN)
goto nosave;
if (m->m_len > iphlen && (m->m_flags & M_EXT) == 0) {
tcp_saveti = m_copym(m, 0, iphlen, M_DONTWAIT);
if (!tcp_saveti)
goto nosave;
} else {
MGETHDR(tcp_saveti, M_DONTWAIT, MT_HEADER);
if (!tcp_saveti)
goto nosave;
MCLAIM(m, &tcp_mowner);
tcp_saveti->m_len = iphlen;
m_copydata(m, 0, iphlen,
mtod(tcp_saveti, caddr_t));
}
if (M_TRAILINGSPACE(tcp_saveti) < sizeof(struct tcphdr)) {
m_freem(tcp_saveti);
tcp_saveti = NULL;
} else {
tcp_saveti->m_len += sizeof(struct tcphdr);
bcopy(th, mtod(tcp_saveti, caddr_t) + iphlen,
sizeof(struct tcphdr));
}
nosave:;
}
if (so->so_options & SO_ACCEPTCONN) {
if ((tiflags & (TH_RST|TH_ACK|TH_SYN)) != TH_SYN) {
if (tiflags & TH_RST) {
syn_cache_reset(&src.sa, &dst.sa, th);
} else if ((tiflags & (TH_ACK|TH_SYN)) ==
(TH_ACK|TH_SYN)) {
/*
* Received a SYN,ACK. This should
* never happen while we are in
* LISTEN. Send an RST.
*/
goto badsyn;
} else if (tiflags & TH_ACK) {
so = syn_cache_get(&src.sa, &dst.sa,
th, toff, tlen, so, m);
if (so == NULL) {
/*
* We don't have a SYN for
* this ACK; send an RST.
*/
goto badsyn;
} else if (so ==
(struct socket *)(-1)) {
/*
* We were unable to create
* the connection. If the
* 3-way handshake was
* completed, and RST has
* been sent to the peer.
* Since the mbuf might be
* in use for the reply,
* do not free it.
*/
m = NULL;
} else {
/*
* We have created a
* full-blown connection.
*/
tp = NULL;
inp = NULL;
#ifdef INET6
in6p = NULL;
#endif
switch (so->so_proto->pr_domain->dom_family) {
#ifdef INET
case AF_INET:
inp = sotoinpcb(so);
tp = intotcpcb(inp);
break;
#endif
#ifdef INET6
case AF_INET6:
in6p = sotoin6pcb(so);
tp = in6totcpcb(in6p);
break;
#endif
}
if (tp == NULL)
goto badsyn; /*XXX*/
tiwin <<= tp->snd_scale;
goto after_listen;
}
} else {
/*
* None of RST, SYN or ACK was set.
* This is an invalid packet for a
* TCB in LISTEN state. Send a RST.
*/
goto badsyn;
}
} else {
/*
* Received a SYN.
*/
#ifdef INET6
/*
* If deprecated address is forbidden, we do
* not accept SYN to deprecated interface
* address to prevent any new inbound
* connection from getting established.
* When we do not accept SYN, we send a TCP
* RST, with deprecated source address (instead
* of dropping it). We compromise it as it is
* much better for peer to send a RST, and
* RST will be the final packet for the
* exchange.
*
* If we do not forbid deprecated addresses, we
* accept the SYN packet. RFC2462 does not
* suggest dropping SYN in this case.
* If we decipher RFC2462 5.5.4, it says like
* this:
* 1. use of deprecated addr with existing
* communication is okay - "SHOULD continue
* to be used"
* 2. use of it with new communication:
* (2a) "SHOULD NOT be used if alternate
* address with sufficient scope is
* available"
* (2b) nothing mentioned otherwise.
* Here we fall into (2b) case as we have no
* choice in our source address selection - we
* must obey the peer.
*
* The wording in RFC2462 is confusing, and
* there are multiple description text for
* deprecated address handling - worse, they
* are not exactly the same. I believe 5.5.4
* is the best one, so we follow 5.5.4.
*/
if (af == AF_INET6 && !ip6_use_deprecated) {
struct in6_ifaddr *ia6;
if ((ia6 = in6ifa_ifpwithaddr(m->m_pkthdr.rcvif,
&ip6->ip6_dst)) &&
(ia6->ia6_flags & IN6_IFF_DEPRECATED)) {
tp = NULL;
goto dropwithreset;
}
}
#endif
#ifdef IPSEC
switch (af) {
case AF_INET:
if (ipsec4_in_reject_so(m, so)) {
ipsecstat.in_polvio++;
tp = NULL;
goto dropwithreset;
}
break;
#ifdef INET6
case AF_INET6:
if (ipsec6_in_reject_so(m, so)) {
ipsec6stat.in_polvio++;
tp = NULL;
goto dropwithreset;
}
break;
#endif
}
#endif
/*
* LISTEN socket received a SYN
* from itself? This can't possibly
* be valid; drop the packet.
*/
if (th->th_sport == th->th_dport) {
int i;
switch (af) {
#ifdef INET
case AF_INET:
i = in_hosteq(ip->ip_src, ip->ip_dst);
break;
#endif
#ifdef INET6
case AF_INET6:
i = IN6_ARE_ADDR_EQUAL(&ip6->ip6_src, &ip6->ip6_dst);
break;
#endif
default:
i = 1;
}
if (i) {
tcpstat.tcps_badsyn++;
goto drop;
}
}
/*
* SYN looks ok; create compressed TCP
* state for it.
*/
if (so->so_qlen <= so->so_qlimit &&
syn_cache_add(&src.sa, &dst.sa, th, tlen,
so, m, optp, optlen, &opti))
m = NULL;
}
goto drop;
}
}
after_listen:
#ifdef DIAGNOSTIC
/*
* Should not happen now that all embryonic connections
* are handled with compressed state.
*/
if (tp->t_state == TCPS_LISTEN)
panic("tcp_input: TCPS_LISTEN");
#endif
/*
* Segment received on connection.
* Reset idle time and keep-alive timer.
*/
tp->t_rcvtime = tcp_now;
if (TCPS_HAVEESTABLISHED(tp->t_state))
TCP_TIMER_ARM(tp, TCPT_KEEP, tcp_keepidle);
/*
* Process options.
*/
if (optp)
tcp_dooptions(tp, optp, optlen, th, &opti);
/*
* Header prediction: check for the two common cases
* of a uni-directional data xfer. If the packet has
* no control flags, is in-sequence, the window didn't
* change and we're not retransmitting, it's a
* candidate. If the length is zero and the ack moved
* forward, we're the sender side of the xfer. Just
* free the data acked & wake any higher level process
* that was blocked waiting for space. If the length
* is non-zero and the ack didn't move, we're the
* receiver side. If we're getting packets in-order
* (the reassembly queue is empty), add the data to
* the socket buffer and note that we need a delayed ack.
*/
if (tp->t_state == TCPS_ESTABLISHED &&
(tiflags & (TH_SYN|TH_FIN|TH_RST|TH_URG|TH_ACK)) == TH_ACK &&
(!opti.ts_present || TSTMP_GEQ(opti.ts_val, tp->ts_recent)) &&
th->th_seq == tp->rcv_nxt &&
tiwin && tiwin == tp->snd_wnd &&
tp->snd_nxt == tp->snd_max) {
/*
* If last ACK falls within this segment's sequence numbers,
* record the timestamp.
*/
if (opti.ts_present &&
SEQ_LEQ(th->th_seq, tp->last_ack_sent) &&
SEQ_LT(tp->last_ack_sent, th->th_seq + tlen)) {
tp->ts_recent_age = TCP_TIMESTAMP(tp);
tp->ts_recent = opti.ts_val;
}
if (tlen == 0) {
if (SEQ_GT(th->th_ack, tp->snd_una) &&
SEQ_LEQ(th->th_ack, tp->snd_max) &&
tp->snd_cwnd >= tp->snd_wnd &&
tp->t_dupacks < tcprexmtthresh) {
/*
* this is a pure ack for outstanding data.
*/
++tcpstat.tcps_predack;
if (opti.ts_present && opti.ts_ecr)
tcp_xmit_timer(tp,
TCP_TIMESTAMP(tp) - opti.ts_ecr + 1);
else if (tp->t_rtttime &&
SEQ_GT(th->th_ack, tp->t_rtseq))
tcp_xmit_timer(tp,
tcp_now - tp->t_rtttime);
acked = th->th_ack - tp->snd_una;
tcpstat.tcps_rcvackpack++;
tcpstat.tcps_rcvackbyte += acked;
ND6_HINT(tp);
if (acked > (tp->t_lastoff - tp->t_inoff))
tp->t_lastm = NULL;
sbdrop(&so->so_snd, acked);
tp->t_lastoff -= acked;
/*
* We want snd_recover to track snd_una to
* avoid sequence wraparound problems for
* very large transfers.
*/
tp->snd_una = tp->snd_recover = th->th_ack;
m_freem(m);
/*
* If all outstanding data are acked, stop
* retransmit timer, otherwise restart timer
* using current (possibly backed-off) value.
* If process is waiting for space,
* wakeup/selwakeup/signal. If data
* are ready to send, let tcp_output
* decide between more output or persist.
*/
if (tp->snd_una == tp->snd_max)
TCP_TIMER_DISARM(tp, TCPT_REXMT);
else if (TCP_TIMER_ISARMED(tp,
TCPT_PERSIST) == 0)
TCP_TIMER_ARM(tp, TCPT_REXMT,
tp->t_rxtcur);
sowwakeup(so);
if (so->so_snd.sb_cc)
(void) tcp_output(tp);
if (tcp_saveti)
m_freem(tcp_saveti);
return;
}
} else if (th->th_ack == tp->snd_una &&
TAILQ_FIRST(&tp->segq) == NULL &&
tlen <= sbspace(&so->so_rcv)) {
/*
* this is a pure, in-sequence data packet
* with nothing on the reassembly queue and
* we have enough buffer space to take it.
*/
++tcpstat.tcps_preddat;
tp->rcv_nxt += tlen;
tcpstat.tcps_rcvpack++;
tcpstat.tcps_rcvbyte += tlen;
ND6_HINT(tp);
/*
* Drop TCP, IP headers and TCP options then add data
* to socket buffer.
*/
if (so->so_state & SS_CANTRCVMORE)
m_freem(m);
else {
m_adj(m, toff + off);
sbappendstream(&so->so_rcv, m);
}
sorwakeup(so);
TCP_SETUP_ACK(tp, th);
if (tp->t_flags & TF_ACKNOW)
(void) tcp_output(tp);
if (tcp_saveti)
m_freem(tcp_saveti);
return;
}
}
/*
* Compute mbuf offset to TCP data segment.
*/
hdroptlen = toff + off;
/*
* Calculate amount of space in receive window,
* and then do TCP input processing.
* Receive window is amount of space in rcv queue,
* but not less than advertised window.
*/
{ int win;
win = sbspace(&so->so_rcv);
if (win < 0)
win = 0;
tp->rcv_wnd = imax(win, (int)(tp->rcv_adv - tp->rcv_nxt));
}
switch (tp->t_state) {
case TCPS_LISTEN:
/*
* RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN
*/
if (m->m_flags & (M_BCAST|M_MCAST))
goto drop;
switch (af) {
#ifdef INET6
case AF_INET6:
if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst))
goto drop;
break;
#endif /* INET6 */
case AF_INET:
if (IN_MULTICAST(ip->ip_dst.s_addr) ||
in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif))
goto drop;
break;
}
break;
/*
* If the state is SYN_SENT:
* if seg contains an ACK, but not for our SYN, drop the input.
* if seg contains a RST, then drop the connection.
* if seg does not contain SYN, then drop it.
* Otherwise this is an acceptable SYN segment
* initialize tp->rcv_nxt and tp->irs
* if seg contains ack then advance tp->snd_una
* if SYN has been acked change to ESTABLISHED else SYN_RCVD state
* arrange for segment to be acked (eventually)
* continue processing rest of data/controls, beginning with URG
*/
case TCPS_SYN_SENT:
if ((tiflags & TH_ACK) &&
(SEQ_LEQ(th->th_ack, tp->iss) ||
SEQ_GT(th->th_ack, tp->snd_max)))
goto dropwithreset;
if (tiflags & TH_RST) {
if (tiflags & TH_ACK)
tp = tcp_drop(tp, ECONNREFUSED);
goto drop;
}
if ((tiflags & TH_SYN) == 0)
goto drop;
if (tiflags & TH_ACK) {
tp->snd_una = tp->snd_recover = th->th_ack;
if (SEQ_LT(tp->snd_nxt, tp->snd_una))
tp->snd_nxt = tp->snd_una;
TCP_TIMER_DISARM(tp, TCPT_REXMT);
}
tp->irs = th->th_seq;
tcp_rcvseqinit(tp);
tp->t_flags |= TF_ACKNOW;
tcp_mss_from_peer(tp, opti.maxseg);
/*
* Initialize the initial congestion window. If we
* had to retransmit the SYN, we must initialize cwnd
* to 1 segment (i.e. the Loss Window).
*/
if (tp->t_flags & TF_SYN_REXMT)
tp->snd_cwnd = tp->t_peermss;
else {
int ss = tcp_init_win;
#ifdef INET
if (inp != NULL && in_localaddr(inp->inp_faddr))
ss = tcp_init_win_local;
#endif
#ifdef INET6
if (in6p != NULL && in6_localaddr(&in6p->in6p_faddr))
ss = tcp_init_win_local;
#endif
tp->snd_cwnd = TCP_INITIAL_WINDOW(ss, tp->t_peermss);
}
tcp_rmx_rtt(tp);
if (tiflags & TH_ACK) {
tcpstat.tcps_connects++;
soisconnected(so);
tcp_established(tp);
/* Do window scaling on this connection? */
if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) ==
(TF_RCVD_SCALE|TF_REQ_SCALE)) {
tp->snd_scale = tp->requested_s_scale;
tp->rcv_scale = tp->request_r_scale;
}
TCP_REASS_LOCK(tp);
(void) tcp_reass(tp, NULL, (struct mbuf *)0, &tlen);
TCP_REASS_UNLOCK(tp);
/*
* if we didn't have to retransmit the SYN,
* use its rtt as our initial srtt & rtt var.
*/
if (tp->t_rtttime)
tcp_xmit_timer(tp, tcp_now - tp->t_rtttime);
} else
tp->t_state = TCPS_SYN_RECEIVED;
/*
* Advance th->th_seq to correspond to first data byte.
* If data, trim to stay within window,
* dropping FIN if necessary.
*/
th->th_seq++;
if (tlen > tp->rcv_wnd) {
todrop = tlen - tp->rcv_wnd;
m_adj(m, -todrop);
tlen = tp->rcv_wnd;
tiflags &= ~TH_FIN;
tcpstat.tcps_rcvpackafterwin++;
tcpstat.tcps_rcvbyteafterwin += todrop;
}
tp->snd_wl1 = th->th_seq - 1;
tp->rcv_up = th->th_seq;
goto step6;
/*
* If the state is SYN_RECEIVED:
* If seg contains an ACK, but not for our SYN, drop the input
* and generate an RST. See page 36, rfc793
*/
case TCPS_SYN_RECEIVED:
if ((tiflags & TH_ACK) &&
(SEQ_LEQ(th->th_ack, tp->iss) ||
SEQ_GT(th->th_ack, tp->snd_max)))
goto dropwithreset;
break;
}
/*
* States other than LISTEN or SYN_SENT.
* First check timestamp, if present.
* Then check that at least some bytes of segment are within
* receive window. If segment begins before rcv_nxt,
* drop leading data (and SYN); if nothing left, just ack.
*
* RFC 1323 PAWS: If we have a timestamp reply on this segment
* and it's less than ts_recent, drop it.
*/
if (opti.ts_present && (tiflags & TH_RST) == 0 && tp->ts_recent &&
TSTMP_LT(opti.ts_val, tp->ts_recent)) {
/* Check to see if ts_recent is over 24 days old. */
if ((int)(TCP_TIMESTAMP(tp) - tp->ts_recent_age) >
TCP_PAWS_IDLE) {
/*
* Invalidate ts_recent. If this segment updates
* ts_recent, the age will be reset later and ts_recent
* will get a valid value. If it does not, setting
* ts_recent to zero will at least satisfy the
* requirement that zero be placed in the timestamp
* echo reply when ts_recent isn't valid. The
* age isn't reset until we get a valid ts_recent
* because we don't want out-of-order segments to be
* dropped when ts_recent is old.
*/
tp->ts_recent = 0;
} else {
tcpstat.tcps_rcvduppack++;
tcpstat.tcps_rcvdupbyte += tlen;
tcpstat.tcps_pawsdrop++;
goto dropafterack;
}
}
todrop = tp->rcv_nxt - th->th_seq;
if (todrop > 0) {
if (tiflags & TH_SYN) {
tiflags &= ~TH_SYN;
th->th_seq++;
if (th->th_urp > 1)
th->th_urp--;
else {
tiflags &= ~TH_URG;
th->th_urp = 0;
}
todrop--;
}
if (todrop > tlen ||
(todrop == tlen && (tiflags & TH_FIN) == 0)) {
/*
* Any valid FIN must be to the left of the window.
* At this point the FIN must be a duplicate or
* out of sequence; drop it.
*/
tiflags &= ~TH_FIN;
/*
* Send an ACK to resynchronize and drop any data.
* But keep on processing for RST or ACK.
*/
tp->t_flags |= TF_ACKNOW;
todrop = tlen;
tcpstat.tcps_rcvdupbyte += todrop;
tcpstat.tcps_rcvduppack++;
} else {
tcpstat.tcps_rcvpartduppack++;
tcpstat.tcps_rcvpartdupbyte += todrop;
}
hdroptlen += todrop; /*drop from head afterwards*/
th->th_seq += todrop;
tlen -= todrop;
if (th->th_urp > todrop)
th->th_urp -= todrop;
else {
tiflags &= ~TH_URG;
th->th_urp = 0;
}
}
/*
* If new data are received on a connection after the
* user processes are gone, then RST the other end.
*/
if ((so->so_state & SS_NOFDREF) &&
tp->t_state > TCPS_CLOSE_WAIT && tlen) {
tp = tcp_close(tp);
tcpstat.tcps_rcvafterclose++;
goto dropwithreset;
}
/*
* If segment ends after window, drop trailing data
* (and PUSH and FIN); if nothing left, just ACK.
*/
todrop = (th->th_seq + tlen) - (tp->rcv_nxt+tp->rcv_wnd);
if (todrop > 0) {
tcpstat.tcps_rcvpackafterwin++;
if (todrop >= tlen) {
tcpstat.tcps_rcvbyteafterwin += tlen;
/*
* If a new connection request is received
* while in TIME_WAIT, drop the old connection
* and start over if the sequence numbers
* are above the previous ones.
*
* NOTE: We will checksum the packet again, and
* so we need to put the header fields back into
* network order!
* XXX This kind of sucks, but we don't expect
* XXX this to happen very often, so maybe it
* XXX doesn't matter so much.
*/
if (tiflags & TH_SYN &&
tp->t_state == TCPS_TIME_WAIT &&
SEQ_GT(th->th_seq, tp->rcv_nxt)) {
iss = tcp_new_iss(tp, tp->snd_nxt);
tp = tcp_close(tp);
TCP_FIELDS_TO_NET(th);
goto findpcb;
}
/*
* If window is closed can only take segments at
* window edge, and have to drop data and PUSH from
* incoming segments. Continue processing, but
* remember to ack. Otherwise, drop segment
* and ack.
*/
if (tp->rcv_wnd == 0 && th->th_seq == tp->rcv_nxt) {
tp->t_flags |= TF_ACKNOW;
tcpstat.tcps_rcvwinprobe++;
} else
goto dropafterack;
} else
tcpstat.tcps_rcvbyteafterwin += todrop;
m_adj(m, -todrop);
tlen -= todrop;
tiflags &= ~(TH_PUSH|TH_FIN);
}
/*
* If last ACK falls within this segment's sequence numbers,
* and the timestamp is newer, record it.
*/
if (opti.ts_present && TSTMP_GEQ(opti.ts_val, tp->ts_recent) &&
SEQ_LEQ(th->th_seq, tp->last_ack_sent) &&
SEQ_LT(tp->last_ack_sent, th->th_seq + tlen +
((tiflags & (TH_SYN|TH_FIN)) != 0))) {
tp->ts_recent_age = TCP_TIMESTAMP(tp);
tp->ts_recent = opti.ts_val;
}
/*
* If the RST bit is set examine the state:
* SYN_RECEIVED STATE:
* If passive open, return to LISTEN state.
* If active open, inform user that connection was refused.
* ESTABLISHED, FIN_WAIT_1, FIN_WAIT2, CLOSE_WAIT STATES:
* Inform user that connection was reset, and close tcb.
* CLOSING, LAST_ACK, TIME_WAIT STATES
* Close the tcb.
*/
if (tiflags&TH_RST) switch (tp->t_state) {
case TCPS_SYN_RECEIVED:
so->so_error = ECONNREFUSED;
goto close;
case TCPS_ESTABLISHED:
case TCPS_FIN_WAIT_1:
case TCPS_FIN_WAIT_2:
case TCPS_CLOSE_WAIT:
so->so_error = ECONNRESET;
close:
tp->t_state = TCPS_CLOSED;
tcpstat.tcps_drops++;
tp = tcp_close(tp);
goto drop;
case TCPS_CLOSING:
case TCPS_LAST_ACK:
case TCPS_TIME_WAIT:
tp = tcp_close(tp);
goto drop;
}
/*
* If a SYN is in the window, then this is an
* error and we send an RST and drop the connection.
*/
if (tiflags & TH_SYN) {
tp = tcp_drop(tp, ECONNRESET);
goto dropwithreset;
}
/*
* If the ACK bit is off we drop the segment and return.
*/
if ((tiflags & TH_ACK) == 0) {
if (tp->t_flags & TF_ACKNOW)
goto dropafterack;
else
goto drop;
}
/*
* Ack processing.
*/
switch (tp->t_state) {
/*
* In SYN_RECEIVED state if the ack ACKs our SYN then enter
* ESTABLISHED state and continue processing, otherwise
* send an RST.
*/
case TCPS_SYN_RECEIVED:
if (SEQ_GT(tp->snd_una, th->th_ack) ||
SEQ_GT(th->th_ack, tp->snd_max))
goto dropwithreset;
tcpstat.tcps_connects++;
soisconnected(so);
tcp_established(tp);
/* Do window scaling? */
if ((tp->t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) ==
(TF_RCVD_SCALE|TF_REQ_SCALE)) {
tp->snd_scale = tp->requested_s_scale;
tp->rcv_scale = tp->request_r_scale;
}
TCP_REASS_LOCK(tp);
(void) tcp_reass(tp, NULL, (struct mbuf *)0, &tlen);
TCP_REASS_UNLOCK(tp);
tp->snd_wl1 = th->th_seq - 1;
/* fall into ... */
/*
* In ESTABLISHED state: drop duplicate ACKs; ACK out of range
* ACKs. If the ack is in the range
* tp->snd_una < th->th_ack <= tp->snd_max
* then advance tp->snd_una to th->th_ack and drop
* data from the retransmission queue. If this ACK reflects
* more up to date window information we update our window information.
*/
case TCPS_ESTABLISHED:
case TCPS_FIN_WAIT_1:
case TCPS_FIN_WAIT_2:
case TCPS_CLOSE_WAIT:
case TCPS_CLOSING:
case TCPS_LAST_ACK:
case TCPS_TIME_WAIT:
if (SEQ_LEQ(th->th_ack, tp->snd_una)) {
if (tlen == 0 && tiwin == tp->snd_wnd) {
tcpstat.tcps_rcvdupack++;
/*
* If we have outstanding data (other than
* a window probe), this is a completely
* duplicate ack (ie, window info didn't
* change), the ack is the biggest we've
* seen and we've seen exactly our rexmt
* threshhold of them, assume a packet
* has been dropped and retransmit it.
* Kludge snd_nxt & the congestion
* window so we send only this one
* packet.
*
* We know we're losing at the current
* window size so do congestion avoidance
* (set ssthresh to half the current window
* and pull our congestion window back to
* the new ssthresh).
*
* Dup acks mean that packets have left the
* network (they're now cached at the receiver)
* so bump cwnd by the amount in the receiver
* to keep a constant cwnd packets in the
* network.
*/
if (TCP_TIMER_ISARMED(tp, TCPT_REXMT) == 0 ||
th->th_ack != tp->snd_una)
tp->t_dupacks = 0;
else if (++tp->t_dupacks == tcprexmtthresh) {
tcp_seq onxt = tp->snd_nxt;
u_int win =
min(tp->snd_wnd, tp->snd_cwnd) /
2 / tp->t_segsz;
if (tcp_do_newreno && SEQ_LT(th->th_ack,
tp->snd_recover)) {
/*
* False fast retransmit after
* timeout. Do not cut window.
*/
tp->snd_cwnd += tp->t_segsz;
tp->t_dupacks = 0;
(void) tcp_output(tp);
goto drop;
}
if (win < 2)
win = 2;
tp->snd_ssthresh = win * tp->t_segsz;
tp->snd_recover = tp->snd_max;
TCP_TIMER_DISARM(tp, TCPT_REXMT);
tp->t_rtttime = 0;
tp->snd_nxt = th->th_ack;
tp->snd_cwnd = tp->t_segsz;
(void) tcp_output(tp);
tp->snd_cwnd = tp->snd_ssthresh +
tp->t_segsz * tp->t_dupacks;
if (SEQ_GT(onxt, tp->snd_nxt))
tp->snd_nxt = onxt;
goto drop;
} else if (tp->t_dupacks > tcprexmtthresh) {
tp->snd_cwnd += tp->t_segsz;
(void) tcp_output(tp);
goto drop;
}
} else
tp->t_dupacks = 0;
break;
}
/*
* If the congestion window was inflated to account
* for the other side's cached packets, retract it.
*/
if (tcp_do_newreno == 0) {
if (tp->t_dupacks >= tcprexmtthresh &&
tp->snd_cwnd > tp->snd_ssthresh)
tp->snd_cwnd = tp->snd_ssthresh;
tp->t_dupacks = 0;
} else if (tp->t_dupacks >= tcprexmtthresh &&
tcp_newreno(tp, th) == 0) {
tp->snd_cwnd = tp->snd_ssthresh;
/*
* Window inflation should have left us with approx.
* snd_ssthresh outstanding data. But in case we
* would be inclined to send a burst, better to do
* it via the slow start mechanism.
*/
if (SEQ_SUB(tp->snd_max, th->th_ack) < tp->snd_ssthresh)
tp->snd_cwnd = SEQ_SUB(tp->snd_max, th->th_ack)
+ tp->t_segsz;
tp->t_dupacks = 0;
}
if (SEQ_GT(th->th_ack, tp->snd_max)) {
tcpstat.tcps_rcvacktoomuch++;
goto dropafterack;
}
acked = th->th_ack - tp->snd_una;
tcpstat.tcps_rcvackpack++;
tcpstat.tcps_rcvackbyte += acked;
/*
* If we have a timestamp reply, update smoothed
* round trip time. If no timestamp is present but
* transmit timer is running and timed sequence
* number was acked, update smoothed round trip time.
* Since we now have an rtt measurement, cancel the
* timer backoff (cf., Phil Karn's retransmit alg.).
* Recompute the initial retransmit timer.
*/
if (opti.ts_present && opti.ts_ecr)
tcp_xmit_timer(tp, TCP_TIMESTAMP(tp) - opti.ts_ecr + 1);
else if (tp->t_rtttime && SEQ_GT(th->th_ack, tp->t_rtseq))
tcp_xmit_timer(tp, tcp_now - tp->t_rtttime);
/*
* If all outstanding data is acked, stop retransmit
* timer and remember to restart (more output or persist).
* If there is more data to be acked, restart retransmit
* timer, using current (possibly backed-off) value.
*/
if (th->th_ack == tp->snd_max) {
TCP_TIMER_DISARM(tp, TCPT_REXMT);
needoutput = 1;
} else if (TCP_TIMER_ISARMED(tp, TCPT_PERSIST) == 0)
TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur);
/*
* When new data is acked, open the congestion window.
* If the window gives us less than ssthresh packets
* in flight, open exponentially (segsz per packet).
* Otherwise open linearly: segsz per window
* (segsz^2 / cwnd per packet), plus a constant
* fraction of a packet (segsz/8) to help larger windows
* open quickly enough.
*/
{
u_int cw = tp->snd_cwnd;
u_int incr = tp->t_segsz;
if (cw > tp->snd_ssthresh)
incr = incr * incr / cw;
if (tcp_do_newreno == 0 || SEQ_GEQ(th->th_ack, tp->snd_recover))
tp->snd_cwnd = min(cw + incr,
TCP_MAXWIN << tp->snd_scale);
}
ND6_HINT(tp);
if (acked > so->so_snd.sb_cc) {
tp->snd_wnd -= so->so_snd.sb_cc;
sbdrop(&so->so_snd, (int)so->so_snd.sb_cc);
ourfinisacked = 1;
} else {
if (acked > (tp->t_lastoff - tp->t_inoff))
tp->t_lastm = NULL;
sbdrop(&so->so_snd, acked);
tp->t_lastoff -= acked;
ourfinisacked = 0;
}
sowwakeup(so);
/*
* We want snd_recover to track snd_una to
* avoid sequence wraparound problems for
* very large transfers.
*/
tp->snd_una = tp->snd_recover = th->th_ack;
if (SEQ_LT(tp->snd_nxt, tp->snd_una))
tp->snd_nxt = tp->snd_una;
switch (tp->t_state) {
/*
* In FIN_WAIT_1 STATE in addition to the processing
* for the ESTABLISHED state if our FIN is now acknowledged
* then enter FIN_WAIT_2.
*/
case TCPS_FIN_WAIT_1:
if (ourfinisacked) {
/*
* If we can't receive any more
* data, then closing user can proceed.
* Starting the timer is contrary to the
* specification, but if we don't get a FIN
* we'll hang forever.
*/
if (so->so_state & SS_CANTRCVMORE) {
soisdisconnected(so);
if (tcp_maxidle > 0)
TCP_TIMER_ARM(tp, TCPT_2MSL,
tcp_maxidle);
}
tp->t_state = TCPS_FIN_WAIT_2;
}
break;
/*
* In CLOSING STATE in addition to the processing for
* the ESTABLISHED state if the ACK acknowledges our FIN
* then enter the TIME-WAIT state, otherwise ignore
* the segment.
*/
case TCPS_CLOSING:
if (ourfinisacked) {
tp->t_state = TCPS_TIME_WAIT;
tcp_canceltimers(tp);
TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL);
soisdisconnected(so);
}
break;
/*
* In LAST_ACK, we may still be waiting for data to drain
* and/or to be acked, as well as for the ack of our FIN.
* If our FIN is now acknowledged, delete the TCB,
* enter the closed state and return.
*/
case TCPS_LAST_ACK:
if (ourfinisacked) {
tp = tcp_close(tp);
goto drop;
}
break;
/*
* In TIME_WAIT state the only thing that should arrive
* is a retransmission of the remote FIN. Acknowledge
* it and restart the finack timer.
*/
case TCPS_TIME_WAIT:
TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL);
goto dropafterack;
}
}
step6:
/*
* Update window information.
* Don't look at window if no ACK: TAC's send garbage on first SYN.
*/
if ((tiflags & TH_ACK) && (SEQ_LT(tp->snd_wl1, th->th_seq) ||
(tp->snd_wl1 == th->th_seq && SEQ_LT(tp->snd_wl2, th->th_ack)) ||
(tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd))) {
/* keep track of pure window updates */
if (tlen == 0 &&
tp->snd_wl2 == th->th_ack && tiwin > tp->snd_wnd)
tcpstat.tcps_rcvwinupd++;
tp->snd_wnd = tiwin;
tp->snd_wl1 = th->th_seq;
tp->snd_wl2 = th->th_ack;
if (tp->snd_wnd > tp->max_sndwnd)
tp->max_sndwnd = tp->snd_wnd;
needoutput = 1;
}
/*
* Process segments with URG.
*/
if ((tiflags & TH_URG) && th->th_urp &&
TCPS_HAVERCVDFIN(tp->t_state) == 0) {
/*
* This is a kludge, but if we receive and accept
* random urgent pointers, we'll crash in
* soreceive. It's hard to imagine someone
* actually wanting to send this much urgent data.
*/
if (th->th_urp + so->so_rcv.sb_cc > sb_max) {
th->th_urp = 0; /* XXX */
tiflags &= ~TH_URG; /* XXX */
goto dodata; /* XXX */
}
/*
* If this segment advances the known urgent pointer,
* then mark the data stream. This should not happen
* in CLOSE_WAIT, CLOSING, LAST_ACK or TIME_WAIT STATES since
* a FIN has been received from the remote side.
* In these states we ignore the URG.
*
* According to RFC961 (Assigned Protocols),
* the urgent pointer points to the last octet
* of urgent data. We continue, however,
* to consider it to indicate the first octet
* of data past the urgent section as the original
* spec states (in one of two places).
*/
if (SEQ_GT(th->th_seq+th->th_urp, tp->rcv_up)) {
tp->rcv_up = th->th_seq + th->th_urp;
so->so_oobmark = so->so_rcv.sb_cc +
(tp->rcv_up - tp->rcv_nxt) - 1;
if (so->so_oobmark == 0)
so->so_state |= SS_RCVATMARK;
sohasoutofband(so);
tp->t_oobflags &= ~(TCPOOB_HAVEDATA | TCPOOB_HADDATA);
}
/*
* Remove out of band data so doesn't get presented to user.
* This can happen independent of advancing the URG pointer,
* but if two URG's are pending at once, some out-of-band
* data may creep in... ick.
*/
if (th->th_urp <= (u_int16_t) tlen
#ifdef SO_OOBINLINE
&& (so->so_options & SO_OOBINLINE) == 0
#endif
)
tcp_pulloutofband(so, th, m, hdroptlen);
} else
/*
* If no out of band data is expected,
* pull receive urgent pointer along
* with the receive window.
*/
if (SEQ_GT(tp->rcv_nxt, tp->rcv_up))
tp->rcv_up = tp->rcv_nxt;
dodata: /* XXX */
/*
* Process the segment text, merging it into the TCP sequencing queue,
* and arranging for acknowledgement of receipt if necessary.
* This process logically involves adjusting tp->rcv_wnd as data
* is presented to the user (this happens in tcp_usrreq.c,
* case PRU_RCVD). If a FIN has already been received on this
* connection then we just ignore the text.
*/
if ((tlen || (tiflags & TH_FIN)) &&
TCPS_HAVERCVDFIN(tp->t_state) == 0) {
/*
* Insert segment ti into reassembly queue of tcp with
* control block tp. Return TH_FIN if reassembly now includes
* a segment with FIN. The macro form does the common case
* inline (segment is the next to be received on an
* established connection, and the queue is empty),
* avoiding linkage into and removal from the queue and
* repetition of various conversions.
* Set DELACK for segments received in order, but ack
* immediately when segments are out of order
* (so fast retransmit can work).
*/
/* NOTE: this was TCP_REASS() macro, but used only once */
TCP_REASS_LOCK(tp);
if (th->th_seq == tp->rcv_nxt &&
TAILQ_FIRST(&tp->segq) == NULL &&
tp->t_state == TCPS_ESTABLISHED) {
TCP_SETUP_ACK(tp, th);
tp->rcv_nxt += tlen;
tiflags = th->th_flags & TH_FIN;
tcpstat.tcps_rcvpack++;
tcpstat.tcps_rcvbyte += tlen;
ND6_HINT(tp);
if (so->so_state & SS_CANTRCVMORE)
m_freem(m);
else {
m_adj(m, hdroptlen);
sbappendstream(&(so)->so_rcv, m);
}
sorwakeup(so);
} else {
m_adj(m, hdroptlen);
tiflags = tcp_reass(tp, th, m, &tlen);
tp->t_flags |= TF_ACKNOW;
}
TCP_REASS_UNLOCK(tp);
/*
* Note the amount of data that peer has sent into
* our window, in order to estimate the sender's
* buffer size.
*/
len = so->so_rcv.sb_hiwat - (tp->rcv_adv - tp->rcv_nxt);
} else {
m_freem(m);
m = NULL;
tiflags &= ~TH_FIN;
}
/*
* If FIN is received ACK the FIN and let the user know
* that the connection is closing. Ignore a FIN received before
* the connection is fully established.
*/
if ((tiflags & TH_FIN) && TCPS_HAVEESTABLISHED(tp->t_state)) {
if (TCPS_HAVERCVDFIN(tp->t_state) == 0) {
socantrcvmore(so);
tp->t_flags |= TF_ACKNOW;
tp->rcv_nxt++;
}
switch (tp->t_state) {
/*
* In ESTABLISHED STATE enter the CLOSE_WAIT state.
*/
case TCPS_ESTABLISHED:
tp->t_state = TCPS_CLOSE_WAIT;
break;
/*
* If still in FIN_WAIT_1 STATE FIN has not been acked so
* enter the CLOSING state.
*/
case TCPS_FIN_WAIT_1:
tp->t_state = TCPS_CLOSING;
break;
/*
* In FIN_WAIT_2 state enter the TIME_WAIT state,
* starting the time-wait timer, turning off the other
* standard timers.
*/
case TCPS_FIN_WAIT_2:
tp->t_state = TCPS_TIME_WAIT;
tcp_canceltimers(tp);
TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL);
soisdisconnected(so);
break;
/*
* In TIME_WAIT state restart the 2 MSL time_wait timer.
*/
case TCPS_TIME_WAIT:
TCP_TIMER_ARM(tp, TCPT_2MSL, 2 * TCPTV_MSL);
break;
}
}
#ifdef TCP_DEBUG
if (so->so_options & SO_DEBUG)
tcp_trace(TA_INPUT, ostate, tp, tcp_saveti, 0);
#endif
/*
* Return any desired output.
*/
if (needoutput || (tp->t_flags & TF_ACKNOW))
(void) tcp_output(tp);
if (tcp_saveti)
m_freem(tcp_saveti);
return;
badsyn:
/*
* Received a bad SYN. Increment counters and dropwithreset.
*/
tcpstat.tcps_badsyn++;
tp = NULL;
goto dropwithreset;
dropafterack:
/*
* Generate an ACK dropping incoming segment if it occupies
* sequence space, where the ACK reflects our state.
*/
if (tiflags & TH_RST)
goto drop;
m_freem(m);
tp->t_flags |= TF_ACKNOW;
(void) tcp_output(tp);
if (tcp_saveti)
m_freem(tcp_saveti);
return;
dropwithreset_ratelim:
/*
* We may want to rate-limit RSTs in certain situations,
* particularly if we are sending an RST in response to
* an attempt to connect to or otherwise communicate with
* a port for which we have no socket.
*/
if (ppsratecheck(&tcp_rst_ppslim_last, &tcp_rst_ppslim_count,
tcp_rst_ppslim) == 0) {
/* XXX stat */
goto drop;
}
/* ...fall into dropwithreset... */
dropwithreset:
/*
* Generate a RST, dropping incoming segment.
* Make ACK acceptable to originator of segment.
*/
if (tiflags & TH_RST)
goto drop;
switch (af) {
#ifdef INET6
case AF_INET6:
/* For following calls to tcp_respond */
if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst))
goto drop;
break;
#endif /* INET6 */
case AF_INET:
if (IN_MULTICAST(ip->ip_dst.s_addr) ||
in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif))
goto drop;
}
if (tiflags & TH_ACK)
(void)tcp_respond(tp, m, m, th, (tcp_seq)0, th->th_ack, TH_RST);
else {
if (tiflags & TH_SYN)
tlen++;
(void)tcp_respond(tp, m, m, th, th->th_seq + tlen, (tcp_seq)0,
TH_RST|TH_ACK);
}
if (tcp_saveti)
m_freem(tcp_saveti);
return;
badcsum:
tcpstat.tcps_rcvbadsum++;
drop:
/*
* Drop space held by incoming segment and return.
*/
if (tp) {
if (tp->t_inpcb)
so = tp->t_inpcb->inp_socket;
#ifdef INET6
else if (tp->t_in6pcb)
so = tp->t_in6pcb->in6p_socket;
#endif
else
so = NULL;
#ifdef TCP_DEBUG
if (so && (so->so_options & SO_DEBUG) != 0)
tcp_trace(TA_DROP, ostate, tp, tcp_saveti, 0);
#endif
}
if (tcp_saveti)
m_freem(tcp_saveti);
m_freem(m);
return;
}
void
tcp_dooptions(tp, cp, cnt, th, oi)
struct tcpcb *tp;
u_char *cp;
int cnt;
struct tcphdr *th;
struct tcp_opt_info *oi;
{
u_int16_t mss;
int opt, optlen;
for (; cnt > 0; cnt -= optlen, cp += optlen) {
opt = cp[0];
if (opt == TCPOPT_EOL)
break;
if (opt == TCPOPT_NOP)
optlen = 1;
else {
if (cnt < 2)
break;
optlen = cp[1];
if (optlen < 2 || optlen > cnt)
break;
}
switch (opt) {
default:
continue;
case TCPOPT_MAXSEG:
if (optlen != TCPOLEN_MAXSEG)
continue;
if (!(th->th_flags & TH_SYN))
continue;
bcopy(cp + 2, &mss, sizeof(mss));
oi->maxseg = ntohs(mss);
break;
case TCPOPT_WINDOW:
if (optlen != TCPOLEN_WINDOW)
continue;
if (!(th->th_flags & TH_SYN))
continue;
tp->t_flags |= TF_RCVD_SCALE;
tp->requested_s_scale = cp[2];
if (tp->requested_s_scale > TCP_MAX_WINSHIFT) {
#if 0 /*XXX*/
char *p;
if (ip)
p = ntohl(ip->ip_src);
#ifdef INET6
else if (ip6)
p = ip6_sprintf(&ip6->ip6_src);
#endif
else
p = "(unknown)";
log(LOG_ERR, "TCP: invalid wscale %d from %s, "
"assuming %d\n",
tp->requested_s_scale, p,
TCP_MAX_WINSHIFT);
#else
log(LOG_ERR, "TCP: invalid wscale %d, "
"assuming %d\n",
tp->requested_s_scale,
TCP_MAX_WINSHIFT);
#endif
tp->requested_s_scale = TCP_MAX_WINSHIFT;
}
break;
case TCPOPT_TIMESTAMP:
if (optlen != TCPOLEN_TIMESTAMP)
continue;
oi->ts_present = 1;
bcopy(cp + 2, &oi->ts_val, sizeof(oi->ts_val));
NTOHL(oi->ts_val);
bcopy(cp + 6, &oi->ts_ecr, sizeof(oi->ts_ecr));
NTOHL(oi->ts_ecr);
/*
* A timestamp received in a SYN makes
* it ok to send timestamp requests and replies.
*/
if (th->th_flags & TH_SYN) {
tp->t_flags |= TF_RCVD_TSTMP;
tp->ts_recent = oi->ts_val;
tp->ts_recent_age = TCP_TIMESTAMP(tp);
}
break;
case TCPOPT_SACK_PERMITTED:
if (optlen != TCPOLEN_SACK_PERMITTED)
continue;
if (!(th->th_flags & TH_SYN))
continue;
tp->t_flags &= ~TF_CANT_TXSACK;
break;
case TCPOPT_SACK:
if (tp->t_flags & TF_IGNR_RXSACK)
continue;
if (optlen % 8 != 2 || optlen < 10)
continue;
cp += 2;
optlen -= 2;
for (; optlen > 0; cp -= 8, optlen -= 8) {
tcp_seq lwe, rwe;
bcopy((char *)cp, (char *) &lwe, sizeof(lwe));
NTOHL(lwe);
bcopy((char *)cp, (char *) &rwe, sizeof(rwe));
NTOHL(rwe);
/* tcp_mark_sacked(tp, lwe, rwe); */
}
break;
}
}
}
/*
* Pull out of band byte out of a segment so
* it doesn't appear in the user's data queue.
* It is still reflected in the segment length for
* sequencing purposes.
*/
void
tcp_pulloutofband(so, th, m, off)
struct socket *so;
struct tcphdr *th;
struct mbuf *m;
int off;
{
int cnt = off + th->th_urp - 1;
while (cnt >= 0) {
if (m->m_len > cnt) {
char *cp = mtod(m, caddr_t) + cnt;
struct tcpcb *tp = sototcpcb(so);
tp->t_iobc = *cp;
tp->t_oobflags |= TCPOOB_HAVEDATA;
bcopy(cp+1, cp, (unsigned)(m->m_len - cnt - 1));
m->m_len--;
return;
}
cnt -= m->m_len;
m = m->m_next;
if (m == 0)
break;
}
panic("tcp_pulloutofband");
}
/*
* Collect new round-trip time estimate
* and update averages and current timeout.
*/
void
tcp_xmit_timer(tp, rtt)
struct tcpcb *tp;
uint32_t rtt;
{
int32_t delta;
tcpstat.tcps_rttupdated++;
if (tp->t_srtt != 0) {
/*
* srtt is stored as fixed point with 3 bits after the
* binary point (i.e., scaled by 8). The following magic
* is equivalent to the smoothing algorithm in rfc793 with
* an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed
* point). Adjust rtt to origin 0.
*/
delta = (rtt << 2) - (tp->t_srtt >> TCP_RTT_SHIFT);
if ((tp->t_srtt += delta) <= 0)
tp->t_srtt = 1 << 2;
/*
* We accumulate a smoothed rtt variance (actually, a
* smoothed mean difference), then set the retransmit
* timer to smoothed rtt + 4 times the smoothed variance.
* rttvar is stored as fixed point with 2 bits after the
* binary point (scaled by 4). The following is
* equivalent to rfc793 smoothing with an alpha of .75
* (rttvar = rttvar*3/4 + |delta| / 4). This replaces
* rfc793's wired-in beta.
*/
if (delta < 0)
delta = -delta;
delta -= (tp->t_rttvar >> TCP_RTTVAR_SHIFT);
if ((tp->t_rttvar += delta) <= 0)
tp->t_rttvar = 1 << 2;
} else {
/*
* No rtt measurement yet - use the unsmoothed rtt.
* Set the variance to half the rtt (so our first
* retransmit happens at 3*rtt).
*/
tp->t_srtt = rtt << (TCP_RTT_SHIFT + 2);
tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT + 2 - 1);
}
tp->t_rtttime = 0;
tp->t_rxtshift = 0;
/*
* the retransmit should happen at rtt + 4 * rttvar.
* Because of the way we do the smoothing, srtt and rttvar
* will each average +1/2 tick of bias. When we compute
* the retransmit timer, we want 1/2 tick of rounding and
* 1 extra tick because of +-1/2 tick uncertainty in the
* firing of the timer. The bias will give us exactly the
* 1.5 tick we need. But, because the bias is
* statistical, we have to test that we don't drop below
* the minimum feasible timer (which is 2 ticks).
*/
TCPT_RANGESET(tp->t_rxtcur, TCP_REXMTVAL(tp),
max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX);
/*
* We received an ack for a packet that wasn't retransmitted;
* it is probably safe to discard any error indications we've
* received recently. This isn't quite right, but close enough
* for now (a route might have failed after we sent a segment,
* and the return path might not be symmetrical).
*/
tp->t_softerror = 0;
}
/*
* Checks for partial ack. If partial ack arrives, force the retransmission
* of the next unacknowledged segment, do not clear tp->t_dupacks, and return
* 1. By setting snd_nxt to th_ack, this forces retransmission timer to
* be started again. If the ack advances at least to tp->snd_recover, return 0.
*/
int
tcp_newreno(tp, th)
struct tcpcb *tp;
struct tcphdr *th;
{
tcp_seq onxt = tp->snd_nxt;
u_long ocwnd = tp->snd_cwnd;
if (SEQ_LT(th->th_ack, tp->snd_recover)) {
/*
* snd_una has not yet been updated and the socket's send
* buffer has not yet drained off the ACK'd data, so we
* have to leave snd_una as it was to get the correct data
* offset in tcp_output().
*/
TCP_TIMER_DISARM(tp, TCPT_REXMT);
tp->t_rtttime = 0;
tp->snd_nxt = th->th_ack;
/*
* Set snd_cwnd to one segment beyond ACK'd offset. snd_una
* is not yet updated when we're called.
*/
tp->snd_cwnd = tp->t_segsz + (th->th_ack - tp->snd_una);
(void) tcp_output(tp);
tp->snd_cwnd = ocwnd;
if (SEQ_GT(onxt, tp->snd_nxt))
tp->snd_nxt = onxt;
/*
* Partial window deflation. Relies on fact that tp->snd_una
* not updated yet.
*/
tp->snd_cwnd -= (th->th_ack - tp->snd_una - tp->t_segsz);
return 1;
}
return 0;
}
/*
* TCP compressed state engine. Currently used to hold compressed
* state for SYN_RECEIVED.
*/
u_long syn_cache_count;
u_int32_t syn_hash1, syn_hash2;
#define SYN_HASH(sa, sp, dp) \
((((sa)->s_addr^syn_hash1)*(((((u_int32_t)(dp))<<16) + \
((u_int32_t)(sp)))^syn_hash2)))
#ifndef INET6
#define SYN_HASHALL(hash, src, dst) \
do { \
hash = SYN_HASH(&((struct sockaddr_in *)(src))->sin_addr, \
((struct sockaddr_in *)(src))->sin_port, \
((struct sockaddr_in *)(dst))->sin_port); \
} while (/*CONSTCOND*/ 0)
#else
#define SYN_HASH6(sa, sp, dp) \
((((sa)->s6_addr32[0] ^ (sa)->s6_addr32[3] ^ syn_hash1) * \
(((((u_int32_t)(dp))<<16) + ((u_int32_t)(sp)))^syn_hash2)) \
& 0x7fffffff)
#define SYN_HASHALL(hash, src, dst) \
do { \
switch ((src)->sa_family) { \
case AF_INET: \
hash = SYN_HASH(&((struct sockaddr_in *)(src))->sin_addr, \
((struct sockaddr_in *)(src))->sin_port, \
((struct sockaddr_in *)(dst))->sin_port); \
break; \
case AF_INET6: \
hash = SYN_HASH6(&((struct sockaddr_in6 *)(src))->sin6_addr, \
((struct sockaddr_in6 *)(src))->sin6_port, \
((struct sockaddr_in6 *)(dst))->sin6_port); \
break; \
default: \
hash = 0; \
} \
} while (/*CONSTCOND*/0)
#endif /* INET6 */
#define SYN_CACHE_RM(sc) \
do { \
TAILQ_REMOVE(&tcp_syn_cache[(sc)->sc_bucketidx].sch_bucket, \
(sc), sc_bucketq); \
(sc)->sc_tp = NULL; \
LIST_REMOVE((sc), sc_tpq); \
tcp_syn_cache[(sc)->sc_bucketidx].sch_length--; \
callout_stop(&(sc)->sc_timer); \
syn_cache_count--; \
} while (/*CONSTCOND*/0)
#define SYN_CACHE_PUT(sc) \
do { \
if ((sc)->sc_ipopts) \
(void) m_free((sc)->sc_ipopts); \
if ((sc)->sc_route4.ro_rt != NULL) \
RTFREE((sc)->sc_route4.ro_rt); \
if (callout_invoking(&(sc)->sc_timer)) \
(sc)->sc_flags |= SCF_DEAD; \
else \
pool_put(&syn_cache_pool, (sc)); \
} while (/*CONSTCOND*/0)
struct pool syn_cache_pool;
/*
* We don't estimate RTT with SYNs, so each packet starts with the default
* RTT and each timer step has a fixed timeout value.
*/
#define SYN_CACHE_TIMER_ARM(sc) \
do { \
TCPT_RANGESET((sc)->sc_rxtcur, \
TCPTV_SRTTDFLT * tcp_backoff[(sc)->sc_rxtshift], TCPTV_MIN, \
TCPTV_REXMTMAX); \
callout_reset(&(sc)->sc_timer, \
(sc)->sc_rxtcur * (hz / PR_SLOWHZ), syn_cache_timer, (sc)); \
} while (/*CONSTCOND*/0)
#define SYN_CACHE_TIMESTAMP(sc) (tcp_now - (sc)->sc_timebase)
void
syn_cache_init()
{
int i;
/* Initialize the hash buckets. */
for (i = 0; i < tcp_syn_cache_size; i++)
TAILQ_INIT(&tcp_syn_cache[i].sch_bucket);
/* Initialize the syn cache pool. */
pool_init(&syn_cache_pool, sizeof(struct syn_cache), 0, 0, 0,
"synpl", NULL);
}
void
syn_cache_insert(sc, tp)
struct syn_cache *sc;
struct tcpcb *tp;
{
struct syn_cache_head *scp;
struct syn_cache *sc2;
int s;
/*
* If there are no entries in the hash table, reinitialize
* the hash secrets.
*/
if (syn_cache_count == 0) {
struct timeval tv;
microtime(&tv);
syn_hash1 = arc4random() ^ (u_long)&sc;
syn_hash2 = arc4random() ^ tv.tv_usec;
}
SYN_HASHALL(sc->sc_hash, &sc->sc_src.sa, &sc->sc_dst.sa);
sc->sc_bucketidx = sc->sc_hash % tcp_syn_cache_size;
scp = &tcp_syn_cache[sc->sc_bucketidx];
/*
* Make sure that we don't overflow the per-bucket
* limit or the total cache size limit.
*/
s = splsoftnet();
if (scp->sch_length >= tcp_syn_bucket_limit) {
tcpstat.tcps_sc_bucketoverflow++;
/*
* The bucket is full. Toss the oldest element in the
* bucket. This will be the first entry in the bucket.
*/
sc2 = TAILQ_FIRST(&scp->sch_bucket);
#ifdef DIAGNOSTIC
/*
* This should never happen; we should always find an
* entry in our bucket.
*/
if (sc2 == NULL)
panic("syn_cache_insert: bucketoverflow: impossible");
#endif
SYN_CACHE_RM(sc2);
SYN_CACHE_PUT(sc2);
} else if (syn_cache_count >= tcp_syn_cache_limit) {
struct syn_cache_head *scp2, *sce;
tcpstat.tcps_sc_overflowed++;
/*
* The cache is full. Toss the oldest entry in the
* first non-empty bucket we can find.
*
* XXX We would really like to toss the oldest
* entry in the cache, but we hope that this
* condition doesn't happen very often.
*/
scp2 = scp;
if (TAILQ_EMPTY(&scp2->sch_bucket)) {
sce = &tcp_syn_cache[tcp_syn_cache_size];
for (++scp2; scp2 != scp; scp2++) {
if (scp2 >= sce)
scp2 = &tcp_syn_cache[0];
if (! TAILQ_EMPTY(&scp2->sch_bucket))
break;
}
#ifdef DIAGNOSTIC
/*
* This should never happen; we should always find a
* non-empty bucket.
*/
if (scp2 == scp)
panic("syn_cache_insert: cacheoverflow: "
"impossible");
#endif
}
sc2 = TAILQ_FIRST(&scp2->sch_bucket);
SYN_CACHE_RM(sc2);
SYN_CACHE_PUT(sc2);
}
/*
* Initialize the entry's timer.
*/
sc->sc_rxttot = 0;
sc->sc_rxtshift = 0;
SYN_CACHE_TIMER_ARM(sc);
/* Link it from tcpcb entry */
LIST_INSERT_HEAD(&tp->t_sc, sc, sc_tpq);
/* Put it into the bucket. */
TAILQ_INSERT_TAIL(&scp->sch_bucket, sc, sc_bucketq);
scp->sch_length++;
syn_cache_count++;
tcpstat.tcps_sc_added++;
splx(s);
}
/*
* Walk the timer queues, looking for SYN,ACKs that need to be retransmitted.
* If we have retransmitted an entry the maximum number of times, expire
* that entry.
*/
void
syn_cache_timer(void *arg)
{
struct syn_cache *sc = arg;
int s;
s = splsoftnet();
callout_ack(&sc->sc_timer);
if (__predict_false(sc->sc_flags & SCF_DEAD)) {
tcpstat.tcps_sc_delayed_free++;
pool_put(&syn_cache_pool, sc);
splx(s);
return;
}
if (__predict_false(sc->sc_rxtshift == TCP_MAXRXTSHIFT)) {
/* Drop it -- too many retransmissions. */
goto dropit;
}
/*
* Compute the total amount of time this entry has
* been on a queue. If this entry has been on longer
* than the keep alive timer would allow, expire it.
*/
sc->sc_rxttot += sc->sc_rxtcur;
if (sc->sc_rxttot >= TCPTV_KEEP_INIT)
goto dropit;
tcpstat.tcps_sc_retransmitted++;
(void) syn_cache_respond(sc, NULL);
/* Advance the timer back-off. */
sc->sc_rxtshift++;
SYN_CACHE_TIMER_ARM(sc);
splx(s);
return;
dropit:
tcpstat.tcps_sc_timed_out++;
SYN_CACHE_RM(sc);
SYN_CACHE_PUT(sc);
splx(s);
}
/*
* Remove syn cache created by the specified tcb entry,
* because this does not make sense to keep them
* (if there's no tcb entry, syn cache entry will never be used)
*/
void
syn_cache_cleanup(tp)
struct tcpcb *tp;
{
struct syn_cache *sc, *nsc;
int s;
s = splsoftnet();
for (sc = LIST_FIRST(&tp->t_sc); sc != NULL; sc = nsc) {
nsc = LIST_NEXT(sc, sc_tpq);
#ifdef DIAGNOSTIC
if (sc->sc_tp != tp)
panic("invalid sc_tp in syn_cache_cleanup");
#endif
SYN_CACHE_RM(sc);
SYN_CACHE_PUT(sc);
}
/* just for safety */
LIST_INIT(&tp->t_sc);
splx(s);
}
/*
* Find an entry in the syn cache.
*/
struct syn_cache *
syn_cache_lookup(src, dst, headp)
struct sockaddr *src;
struct sockaddr *dst;
struct syn_cache_head **headp;
{
struct syn_cache *sc;
struct syn_cache_head *scp;
u_int32_t hash;
int s;
SYN_HASHALL(hash, src, dst);
scp = &tcp_syn_cache[hash % tcp_syn_cache_size];
*headp = scp;
s = splsoftnet();
for (sc = TAILQ_FIRST(&scp->sch_bucket); sc != NULL;
sc = TAILQ_NEXT(sc, sc_bucketq)) {
if (sc->sc_hash != hash)
continue;
if (!bcmp(&sc->sc_src, src, src->sa_len) &&
!bcmp(&sc->sc_dst, dst, dst->sa_len)) {
splx(s);
return (sc);
}
}
splx(s);
return (NULL);
}
/*
* This function gets called when we receive an ACK for a
* socket in the LISTEN state. We look up the connection
* in the syn cache, and if its there, we pull it out of
* the cache and turn it into a full-blown connection in
* the SYN-RECEIVED state.
*
* The return values may not be immediately obvious, and their effects
* can be subtle, so here they are:
*
* NULL SYN was not found in cache; caller should drop the
* packet and send an RST.
*
* -1 We were unable to create the new connection, and are
* aborting it. An ACK,RST is being sent to the peer
* (unless we got screwey sequence numbners; see below),
* because the 3-way handshake has been completed. Caller
* should not free the mbuf, since we may be using it. If
* we are not, we will free it.
*
* Otherwise, the return value is a pointer to the new socket
* associated with the connection.
*/
struct socket *
syn_cache_get(src, dst, th, hlen, tlen, so, m)
struct sockaddr *src;
struct sockaddr *dst;
struct tcphdr *th;
unsigned int hlen, tlen;
struct socket *so;
struct mbuf *m;
{
struct syn_cache *sc;
struct syn_cache_head *scp;
struct inpcb *inp = NULL;
#ifdef INET6
struct in6pcb *in6p = NULL;
#endif
struct tcpcb *tp = 0;
struct mbuf *am;
int s;
struct socket *oso;
s = splsoftnet();
if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) {
splx(s);
return (NULL);
}
/*
* Verify the sequence and ack numbers. Try getting the correct
* response again.
*/
if ((th->th_ack != sc->sc_iss + 1) ||
SEQ_LEQ(th->th_seq, sc->sc_irs) ||
SEQ_GT(th->th_seq, sc->sc_irs + 1 + sc->sc_win)) {
(void) syn_cache_respond(sc, m);
splx(s);
return ((struct socket *)(-1));
}
/* Remove this cache entry */
SYN_CACHE_RM(sc);
splx(s);
/*
* Ok, create the full blown connection, and set things up
* as they would have been set up if we had created the
* connection when the SYN arrived. If we can't create
* the connection, abort it.
*/
/*
* inp still has the OLD in_pcb stuff, set the
* v6-related flags on the new guy, too. This is
* done particularly for the case where an AF_INET6
* socket is bound only to a port, and a v4 connection
* comes in on that port.
* we also copy the flowinfo from the original pcb
* to the new one.
*/
oso = so;
so = sonewconn(so, SS_ISCONNECTED);
if (so == NULL)
goto resetandabort;
switch (so->so_proto->pr_domain->dom_family) {
#ifdef INET
case AF_INET:
inp = sotoinpcb(so);
break;
#endif
#ifdef INET6
case AF_INET6:
in6p = sotoin6pcb(so);
break;
#endif
}
switch (src->sa_family) {
#ifdef INET
case AF_INET:
if (inp) {
inp->inp_laddr = ((struct sockaddr_in *)dst)->sin_addr;
inp->inp_lport = ((struct sockaddr_in *)dst)->sin_port;
inp->inp_options = ip_srcroute();
in_pcbstate(inp, INP_BOUND);
if (inp->inp_options == NULL) {
inp->inp_options = sc->sc_ipopts;
sc->sc_ipopts = NULL;
}
}
#ifdef INET6
else if (in6p) {
/* IPv4 packet to AF_INET6 socket */
bzero(&in6p->in6p_laddr, sizeof(in6p->in6p_laddr));
in6p->in6p_laddr.s6_addr16[5] = htons(0xffff);
bcopy(&((struct sockaddr_in *)dst)->sin_addr,
&in6p->in6p_laddr.s6_addr32[3],
sizeof(((struct sockaddr_in *)dst)->sin_addr));
in6p->in6p_lport = ((struct sockaddr_in *)dst)->sin_port;
in6totcpcb(in6p)->t_family = AF_INET;
if (sotoin6pcb(oso)->in6p_flags & IN6P_IPV6_V6ONLY)
in6p->in6p_flags |= IN6P_IPV6_V6ONLY;
else
in6p->in6p_flags &= ~IN6P_IPV6_V6ONLY;
in6_pcbstate(in6p, IN6P_BOUND);
}
#endif
break;
#endif
#ifdef INET6
case AF_INET6:
if (in6p) {
in6p->in6p_laddr = ((struct sockaddr_in6 *)dst)->sin6_addr;
in6p->in6p_lport = ((struct sockaddr_in6 *)dst)->sin6_port;
in6_pcbstate(in6p, IN6P_BOUND);
}
break;
#endif
}
#ifdef INET6
if (in6p && in6totcpcb(in6p)->t_family == AF_INET6 && sotoinpcb(oso)) {
struct in6pcb *oin6p = sotoin6pcb(oso);
/* inherit socket options from the listening socket */
in6p->in6p_flags |= (oin6p->in6p_flags & IN6P_CONTROLOPTS);
if (in6p->in6p_flags & IN6P_CONTROLOPTS) {
m_freem(in6p->in6p_options);
in6p->in6p_options = 0;
}
ip6_savecontrol(in6p, &in6p->in6p_options,
mtod(m, struct ip6_hdr *), m);
}
#endif
#if defined(IPSEC) || defined(FAST_IPSEC)
/*
* we make a copy of policy, instead of sharing the policy,
* for better behavior in terms of SA lookup and dead SA removal.
*/
if (inp) {
/* copy old policy into new socket's */
if (ipsec_copy_pcbpolicy(sotoinpcb(oso)->inp_sp, inp->inp_sp))
printf("tcp_input: could not copy policy\n");
}
#ifdef INET6
else if (in6p) {
/* copy old policy into new socket's */
if (ipsec_copy_pcbpolicy(sotoin6pcb(oso)->in6p_sp,
in6p->in6p_sp))
printf("tcp_input: could not copy policy\n");
}
#endif
#endif
/*
* Give the new socket our cached route reference.
*/
if (inp)
inp->inp_route = sc->sc_route4; /* struct assignment */
#ifdef INET6
else
in6p->in6p_route = sc->sc_route6;
#endif
sc->sc_route4.ro_rt = NULL;
am = m_get(M_DONTWAIT, MT_SONAME); /* XXX */
if (am == NULL)
goto resetandabort;
MCLAIM(am, &tcp_mowner);
am->m_len = src->sa_len;
bcopy(src, mtod(am, caddr_t), src->sa_len);
if (inp) {
if (in_pcbconnect(inp, am)) {
(void) m_free(am);
goto resetandabort;
}
}
#ifdef INET6
else if (in6p) {
if (src->sa_family == AF_INET) {
/* IPv4 packet to AF_INET6 socket */
struct sockaddr_in6 *sin6;
sin6 = mtod(am, struct sockaddr_in6 *);
am->m_len = sizeof(*sin6);
bzero(sin6, sizeof(*sin6));
sin6->sin6_family = AF_INET6;
sin6->sin6_len = sizeof(*sin6);
sin6->sin6_port = ((struct sockaddr_in *)src)->sin_port;
sin6->sin6_addr.s6_addr16[5] = htons(0xffff);
bcopy(&((struct sockaddr_in *)src)->sin_addr,
&sin6->sin6_addr.s6_addr32[3],
sizeof(sin6->sin6_addr.s6_addr32[3]));
}
if (in6_pcbconnect(in6p, am)) {
(void) m_free(am);
goto resetandabort;
}
}
#endif
else {
(void) m_free(am);
goto resetandabort;
}
(void) m_free(am);
if (inp)
tp = intotcpcb(inp);
#ifdef INET6
else if (in6p)
tp = in6totcpcb(in6p);
#endif
else
tp = NULL;
tp->t_flags = sototcpcb(oso)->t_flags & TF_NODELAY;
if (sc->sc_request_r_scale != 15) {
tp->requested_s_scale = sc->sc_requested_s_scale;
tp->request_r_scale = sc->sc_request_r_scale;
tp->snd_scale = sc->sc_requested_s_scale;
tp->rcv_scale = sc->sc_request_r_scale;
tp->t_flags |= TF_REQ_SCALE|TF_RCVD_SCALE;
}
if (sc->sc_flags & SCF_TIMESTAMP)
tp->t_flags |= TF_REQ_TSTMP|TF_RCVD_TSTMP;
tp->ts_timebase = sc->sc_timebase;
tp->t_template = tcp_template(tp);
if (tp->t_template == 0) {
tp = tcp_drop(tp, ENOBUFS); /* destroys socket */
so = NULL;
m_freem(m);
goto abort;
}
tp->iss = sc->sc_iss;
tp->irs = sc->sc_irs;
tcp_sendseqinit(tp);
tcp_rcvseqinit(tp);
tp->t_state = TCPS_SYN_RECEIVED;
TCP_TIMER_ARM(tp, TCPT_KEEP, TCPTV_KEEP_INIT);
tcpstat.tcps_accepts++;
/* Initialize tp->t_ourmss before we deal with the peer's! */
tp->t_ourmss = sc->sc_ourmaxseg;
tcp_mss_from_peer(tp, sc->sc_peermaxseg);
/*
* Initialize the initial congestion window. If we
* had to retransmit the SYN,ACK, we must initialize cwnd
* to 1 segment (i.e. the Loss Window).
*/
if (sc->sc_rxtshift)
tp->snd_cwnd = tp->t_peermss;
else {
int ss = tcp_init_win;
#ifdef INET
if (inp != NULL && in_localaddr(inp->inp_faddr))
ss = tcp_init_win_local;
#endif
#ifdef INET6
if (in6p != NULL && in6_localaddr(&in6p->in6p_faddr))
ss = tcp_init_win_local;
#endif
tp->snd_cwnd = TCP_INITIAL_WINDOW(ss, tp->t_peermss);
}
tcp_rmx_rtt(tp);
tp->snd_wl1 = sc->sc_irs;
tp->rcv_up = sc->sc_irs + 1;
/*
* This is what whould have happened in tcp_output() when
* the SYN,ACK was sent.
*/
tp->snd_up = tp->snd_una;
tp->snd_max = tp->snd_nxt = tp->iss+1;
TCP_TIMER_ARM(tp, TCPT_REXMT, tp->t_rxtcur);
if (sc->sc_win > 0 && SEQ_GT(tp->rcv_nxt + sc->sc_win, tp->rcv_adv))
tp->rcv_adv = tp->rcv_nxt + sc->sc_win;
tp->last_ack_sent = tp->rcv_nxt;
tcpstat.tcps_sc_completed++;
SYN_CACHE_PUT(sc);
return (so);
resetandabort:
(void) tcp_respond(NULL, m, m, th,
th->th_seq + tlen, (tcp_seq)0, TH_RST|TH_ACK);
abort:
if (so != NULL)
(void) soabort(so);
SYN_CACHE_PUT(sc);
tcpstat.tcps_sc_aborted++;
return ((struct socket *)(-1));
}
/*
* This function is called when we get a RST for a
* non-existent connection, so that we can see if the
* connection is in the syn cache. If it is, zap it.
*/
void
syn_cache_reset(src, dst, th)
struct sockaddr *src;
struct sockaddr *dst;
struct tcphdr *th;
{
struct syn_cache *sc;
struct syn_cache_head *scp;
int s = splsoftnet();
if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) {
splx(s);
return;
}
if (SEQ_LT(th->th_seq, sc->sc_irs) ||
SEQ_GT(th->th_seq, sc->sc_irs+1)) {
splx(s);
return;
}
SYN_CACHE_RM(sc);
splx(s);
tcpstat.tcps_sc_reset++;
SYN_CACHE_PUT(sc);
}
void
syn_cache_unreach(src, dst, th)
struct sockaddr *src;
struct sockaddr *dst;
struct tcphdr *th;
{
struct syn_cache *sc;
struct syn_cache_head *scp;
int s;
s = splsoftnet();
if ((sc = syn_cache_lookup(src, dst, &scp)) == NULL) {
splx(s);
return;
}
/* If the sequence number != sc_iss, then it's a bogus ICMP msg */
if (ntohl (th->th_seq) != sc->sc_iss) {
splx(s);
return;
}
/*
* If we've rertransmitted 3 times and this is our second error,
* we remove the entry. Otherwise, we allow it to continue on.
* This prevents us from incorrectly nuking an entry during a
* spurious network outage.
*
* See tcp_notify().
*/
if ((sc->sc_flags & SCF_UNREACH) == 0 || sc->sc_rxtshift < 3) {
sc->sc_flags |= SCF_UNREACH;
splx(s);
return;
}
SYN_CACHE_RM(sc);
splx(s);
tcpstat.tcps_sc_unreach++;
SYN_CACHE_PUT(sc);
}
/*
* Given a LISTEN socket and an inbound SYN request, add
* this to the syn cache, and send back a segment:
* <SEQ=ISS><ACK=RCV_NXT><CTL=SYN,ACK>
* to the source.
*
* IMPORTANT NOTE: We do _NOT_ ACK data that might accompany the SYN.
* Doing so would require that we hold onto the data and deliver it
* to the application. However, if we are the target of a SYN-flood
* DoS attack, an attacker could send data which would eventually
* consume all available buffer space if it were ACKed. By not ACKing
* the data, we avoid this DoS scenario.
*/
int
syn_cache_add(src, dst, th, hlen, so, m, optp, optlen, oi)
struct sockaddr *src;
struct sockaddr *dst;
struct tcphdr *th;
unsigned int hlen;
struct socket *so;
struct mbuf *m;
u_char *optp;
int optlen;
struct tcp_opt_info *oi;
{
struct tcpcb tb, *tp;
long win;
struct syn_cache *sc;
struct syn_cache_head *scp;
struct mbuf *ipopts;
tp = sototcpcb(so);
/*
* RFC1122 4.2.3.10, p. 104: discard bcast/mcast SYN
*
* Note this check is performed in tcp_input() very early on.
*/
/*
* Initialize some local state.
*/
win = sbspace(&so->so_rcv);
if (win > TCP_MAXWIN)
win = TCP_MAXWIN;
switch (src->sa_family) {
#ifdef INET
case AF_INET:
/*
* Remember the IP options, if any.
*/
ipopts = ip_srcroute();
break;
#endif
default:
ipopts = NULL;
}
if (optp) {
tb.t_flags = tcp_do_rfc1323 ? (TF_REQ_SCALE|TF_REQ_TSTMP) : 0;
tcp_dooptions(&tb, optp, optlen, th, oi);
} else
tb.t_flags = 0;
/*
* See if we already have an entry for this connection.
* If we do, resend the SYN,ACK. We do not count this
* as a retransmission (XXX though maybe we should).
*/
if ((sc = syn_cache_lookup(src, dst, &scp)) != NULL) {
tcpstat.tcps_sc_dupesyn++;
if (ipopts) {
/*
* If we were remembering a previous source route,
* forget it and use the new one we've been given.
*/
if (sc->sc_ipopts)
(void) m_free(sc->sc_ipopts);
sc->sc_ipopts = ipopts;
}
sc->sc_timestamp = tb.ts_recent;
if (syn_cache_respond(sc, m) == 0) {
tcpstat.tcps_sndacks++;
tcpstat.tcps_sndtotal++;
}
return (1);
}
sc = pool_get(&syn_cache_pool, PR_NOWAIT);
if (sc == NULL) {
if (ipopts)
(void) m_free(ipopts);
return (0);
}
/*
* Fill in the cache, and put the necessary IP and TCP
* options into the reply.
*/
bzero(sc, sizeof(struct syn_cache));
callout_init(&sc->sc_timer);
bcopy(src, &sc->sc_src, src->sa_len);
bcopy(dst, &sc->sc_dst, dst->sa_len);
sc->sc_flags = 0;
sc->sc_ipopts = ipopts;
sc->sc_irs = th->th_seq;
switch (src->sa_family) {
#ifdef INET
case AF_INET:
{
struct sockaddr_in *srcin = (void *) src;
struct sockaddr_in *dstin = (void *) dst;
sc->sc_iss = tcp_new_iss1(&dstin->sin_addr,
&srcin->sin_addr, dstin->sin_port,
srcin->sin_port, sizeof(dstin->sin_addr), 0);
break;
}
#endif /* INET */
#ifdef INET6
case AF_INET6:
{
struct sockaddr_in6 *srcin6 = (void *) src;
struct sockaddr_in6 *dstin6 = (void *) dst;
sc->sc_iss = tcp_new_iss1(&dstin6->sin6_addr,
&srcin6->sin6_addr, dstin6->sin6_port,
srcin6->sin6_port, sizeof(dstin6->sin6_addr), 0);
break;
}
#endif /* INET6 */
}
sc->sc_peermaxseg = oi->maxseg;
sc->sc_ourmaxseg = tcp_mss_to_advertise(m->m_flags & M_PKTHDR ?
m->m_pkthdr.rcvif : NULL,
sc->sc_src.sa.sa_family);
sc->sc_win = win;
sc->sc_timebase = tcp_now; /* see tcp_newtcpcb() */
sc->sc_timestamp = tb.ts_recent;
if ((tb.t_flags & (TF_REQ_TSTMP|TF_RCVD_TSTMP)) ==
(TF_REQ_TSTMP|TF_RCVD_TSTMP))
sc->sc_flags |= SCF_TIMESTAMP;
if ((tb.t_flags & (TF_RCVD_SCALE|TF_REQ_SCALE)) ==
(TF_RCVD_SCALE|TF_REQ_SCALE)) {
sc->sc_requested_s_scale = tb.requested_s_scale;
sc->sc_request_r_scale = 0;
while (sc->sc_request_r_scale < TCP_MAX_WINSHIFT &&
TCP_MAXWIN << sc->sc_request_r_scale <
so->so_rcv.sb_hiwat)
sc->sc_request_r_scale++;
} else {
sc->sc_requested_s_scale = 15;
sc->sc_request_r_scale = 15;
}
sc->sc_tp = tp;
if (syn_cache_respond(sc, m) == 0) {
syn_cache_insert(sc, tp);
tcpstat.tcps_sndacks++;
tcpstat.tcps_sndtotal++;
} else {
SYN_CACHE_PUT(sc);
tcpstat.tcps_sc_dropped++;
}
return (1);
}
int
syn_cache_respond(sc, m)
struct syn_cache *sc;
struct mbuf *m;
{
struct route *ro;
u_int8_t *optp;
int optlen, error;
u_int16_t tlen;
struct ip *ip = NULL;
#ifdef INET6
struct ip6_hdr *ip6 = NULL;
#endif
struct tcpcb *tp;
struct tcphdr *th;
u_int hlen;
struct socket *so;
switch (sc->sc_src.sa.sa_family) {
case AF_INET:
hlen = sizeof(struct ip);
ro = &sc->sc_route4;
break;
#ifdef INET6
case AF_INET6:
hlen = sizeof(struct ip6_hdr);
ro = (struct route *)&sc->sc_route6;
break;
#endif
default:
if (m)
m_freem(m);
return EAFNOSUPPORT;
}
/* Compute the size of the TCP options. */
optlen = 4 + (sc->sc_request_r_scale != 15 ? 4 : 0) +
((sc->sc_flags & SCF_TIMESTAMP) ? TCPOLEN_TSTAMP_APPA : 0);
tlen = hlen + sizeof(struct tcphdr) + optlen;
/*
* Create the IP+TCP header from scratch.
*/
if (m)
m_freem(m);
#ifdef DIAGNOSTIC
if (max_linkhdr + tlen > MCLBYTES)
return (ENOBUFS);
#endif
MGETHDR(m, M_DONTWAIT, MT_DATA);
if (m && tlen > MHLEN) {
MCLGET(m, M_DONTWAIT);
if ((m->m_flags & M_EXT) == 0) {
m_freem(m);
m = NULL;
}
}
if (m == NULL)
return (ENOBUFS);
MCLAIM(m, &tcp_tx_mowner);
/* Fixup the mbuf. */
m->m_data += max_linkhdr;
m->m_len = m->m_pkthdr.len = tlen;
if (sc->sc_tp) {
tp = sc->sc_tp;
if (tp->t_inpcb)
so = tp->t_inpcb->inp_socket;
#ifdef INET6
else if (tp->t_in6pcb)
so = tp->t_in6pcb->in6p_socket;
#endif
else
so = NULL;
} else
so = NULL;
m->m_pkthdr.rcvif = NULL;
memset(mtod(m, u_char *), 0, tlen);
switch (sc->sc_src.sa.sa_family) {
case AF_INET:
ip = mtod(m, struct ip *);
ip->ip_dst = sc->sc_src.sin.sin_addr;
ip->ip_src = sc->sc_dst.sin.sin_addr;
ip->ip_p = IPPROTO_TCP;
th = (struct tcphdr *)(ip + 1);
th->th_dport = sc->sc_src.sin.sin_port;
th->th_sport = sc->sc_dst.sin.sin_port;
break;
#ifdef INET6
case AF_INET6:
ip6 = mtod(m, struct ip6_hdr *);
ip6->ip6_dst = sc->sc_src.sin6.sin6_addr;
ip6->ip6_src = sc->sc_dst.sin6.sin6_addr;
ip6->ip6_nxt = IPPROTO_TCP;
/* ip6_plen will be updated in ip6_output() */
th = (struct tcphdr *)(ip6 + 1);
th->th_dport = sc->sc_src.sin6.sin6_port;
th->th_sport = sc->sc_dst.sin6.sin6_port;
break;
#endif
default:
th = NULL;
}
th->th_seq = htonl(sc->sc_iss);
th->th_ack = htonl(sc->sc_irs + 1);
th->th_off = (sizeof(struct tcphdr) + optlen) >> 2;
th->th_flags = TH_SYN|TH_ACK;
th->th_win = htons(sc->sc_win);
/* th_sum already 0 */
/* th_urp already 0 */
/* Tack on the TCP options. */
optp = (u_int8_t *)(th + 1);
*optp++ = TCPOPT_MAXSEG;
*optp++ = 4;
*optp++ = (sc->sc_ourmaxseg >> 8) & 0xff;
*optp++ = sc->sc_ourmaxseg & 0xff;
if (sc->sc_request_r_scale != 15) {
*((u_int32_t *)optp) = htonl(TCPOPT_NOP << 24 |
TCPOPT_WINDOW << 16 | TCPOLEN_WINDOW << 8 |
sc->sc_request_r_scale);
optp += 4;
}
if (sc->sc_flags & SCF_TIMESTAMP) {
u_int32_t *lp = (u_int32_t *)(optp);
/* Form timestamp option as shown in appendix A of RFC 1323. */
*lp++ = htonl(TCPOPT_TSTAMP_HDR);
*lp++ = htonl(SYN_CACHE_TIMESTAMP(sc));
*lp = htonl(sc->sc_timestamp);
optp += TCPOLEN_TSTAMP_APPA;
}
/* Compute the packet's checksum. */
switch (sc->sc_src.sa.sa_family) {
case AF_INET:
ip->ip_len = htons(tlen - hlen);
th->th_sum = 0;
th->th_sum = in_cksum(m, tlen);
break;
#ifdef INET6
case AF_INET6:
ip6->ip6_plen = htons(tlen - hlen);
th->th_sum = 0;
th->th_sum = in6_cksum(m, IPPROTO_TCP, hlen, tlen - hlen);
break;
#endif
}
/*
* Fill in some straggling IP bits. Note the stack expects
* ip_len to be in host order, for convenience.
*/
switch (sc->sc_src.sa.sa_family) {
#ifdef INET
case AF_INET:
ip->ip_len = htons(tlen);
ip->ip_ttl = ip_defttl;
/* XXX tos? */
break;
#endif
#ifdef INET6
case AF_INET6:
ip6->ip6_vfc &= ~IPV6_VERSION_MASK;
ip6->ip6_vfc |= IPV6_VERSION;
ip6->ip6_plen = htons(tlen - hlen);
/* ip6_hlim will be initialized afterwards */
/* XXX flowlabel? */
break;
#endif
}
/* XXX use IPsec policy on listening socket, on SYN ACK */
tp = sc->sc_tp;
switch (sc->sc_src.sa.sa_family) {
#ifdef INET
case AF_INET:
error = ip_output(m, sc->sc_ipopts, ro,
(ip_mtudisc ? IP_MTUDISC : 0),
(struct ip_moptions *)NULL, so);
break;
#endif
#ifdef INET6
case AF_INET6:
ip6->ip6_hlim = in6_selecthlim(NULL,
ro->ro_rt ? ro->ro_rt->rt_ifp : NULL);
error = ip6_output(m, NULL /*XXX*/, (struct route_in6 *)ro, 0,
(struct ip6_moptions *)0, so, NULL);
break;
#endif
default:
error = EAFNOSUPPORT;
break;
}
return (error);
}
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