xref: /src/sys/netinet/tcp_var.h

/*	$NetBSD: tcp_var.h,v 1.78 2001/03/20 20:07:52 thorpej Exp $	*/

/*
%%% portions-copyright-nrl-98
Portions of this software are Copyright 1998 by Randall Atkinson,
Ronald Lee, Daniel McDonald, Bao Phan, and Chris Winters. All Rights
Reserved. All rights under this copyright have been assigned to the US
Naval Research Laboratory (NRL). The NRL Copyright Notice and License
Agreement Version 1.1 (January 17, 1995) applies to these portions of the
software.
You should have received a copy of the license with this software. If you
didn't get a copy, you may request one from <license (at) ipv6.nrl.navy.mil>.

*/

/*
 * 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 (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 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, 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. 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_var.h	8.4 (Berkeley) 5/24/95
 */

#ifndef _NETINET_TCP_VAR_H_
#define _NETINET_TCP_VAR_H_

#if defined(_KERNEL) && !defined(_LKM)
#include "opt_inet.h"
#endif

/*
 * Kernel variables for tcp.
 */

/*
 * Tcp control block, one per tcp; fields:
 */
struct tcpcb {
	int	t_family;		/* address family on the wire */
	struct ipqehead segq;		/* sequencing queue */
	u_int	t_timer[TCPT_NTIMERS];	/* tcp timers */
	short	t_state;		/* state of this connection */
	short	t_rxtshift;		/* log(2) of rexmt exp. backoff */
	short	t_rxtcur;		/* current retransmit value */
	short	t_dupacks;		/* consecutive dup acks recd */
	u_short	t_peermss;		/* peer's maximum segment size */
	u_short	t_ourmss;		/* our's maximum segment size */
	u_short t_segsz;		/* current segment size in use */
	char	t_force;		/* 1 if forcing out a byte */
	u_short	t_flags;
#define	TF_ACKNOW	0x0001		/* ack peer immediately */
#define	TF_DELACK	0x0002		/* ack, but try to delay it */
#define	TF_NODELAY	0x0004		/* don't delay packets to coalesce */
#define	TF_NOOPT	0x0008		/* don't use tcp options */
#define	TF_REQ_SCALE	0x0020		/* have/will request window scaling */
#define	TF_RCVD_SCALE	0x0040		/* other side has requested scaling */
#define	TF_REQ_TSTMP	0x0080		/* have/will request timestamps */
#define	TF_RCVD_TSTMP	0x0100		/* a timestamp was received in SYN */
#define	TF_SACK_PERMIT	0x0200		/* other side said I could SACK */
#define	TF_SYN_REXMT	0x0400		/* rexmit timer fired on SYN */
#define	TF_WILL_SACK	0x0800		/* try to use SACK */
#define	TF_CANT_TXSACK	0x1000		/* other side said I could not SACK */
#define	TF_IGNR_RXSACK	0x2000		/* ignore received SACK blocks */
#define	TF_REASSEMBLING	0x4000		/* we're busy reassembling */


	struct	mbuf *t_template;	/* skeletal packet for transmit */
	struct	inpcb *t_inpcb;		/* back pointer to internet pcb */
	struct	in6pcb *t_in6pcb;	/* back pointer to internet pcb */
	LIST_ENTRY(tcpcb) t_delack;	/* delayed ACK queue */
/*
 * The following fields are used as in the protocol specification.
 * See RFC783, Dec. 1981, page 21.
 */
/* send sequence variables */
	tcp_seq	snd_una;		/* send unacknowledged */
	tcp_seq	snd_nxt;		/* send next */
	tcp_seq	snd_up;			/* send urgent pointer */
	tcp_seq	snd_wl1;		/* window update seg seq number */
	tcp_seq	snd_wl2;		/* window update seg ack number */
	tcp_seq	iss;			/* initial send sequence number */
	u_long	snd_wnd;		/* send window */
	tcp_seq snd_recover;		/* for use in fast recovery */
/* receive sequence variables */
	u_long	rcv_wnd;		/* receive window */
	tcp_seq	rcv_nxt;		/* receive next */
	tcp_seq	rcv_up;			/* receive urgent pointer */
	tcp_seq	irs;			/* initial receive sequence number */
/*
 * Additional variables for this implementation.
 */
/* receive variables */
	tcp_seq	rcv_adv;		/* advertised window */
/* retransmit variables */
	tcp_seq	snd_max;		/* highest sequence number sent;
					 * used to recognize retransmits
					 */
/* congestion control (for slow start, source quench, retransmit after loss) */
	u_long	snd_cwnd;		/* congestion-controlled window */
	u_long	snd_ssthresh;		/* snd_cwnd size threshhold for
					 * for slow start exponential to
					 * linear switch
					 */
/*
 * transmit timing stuff.  See below for scale of srtt and rttvar.
 * "Variance" is actually smoothed difference.
 */
	short	t_idle;			/* inactivity time */
	short	t_rtt;			/* round trip time */
	tcp_seq	t_rtseq;		/* sequence number being timed */
	short	t_srtt;			/* smoothed round-trip time */
	short	t_rttvar;		/* variance in round-trip time */
	short	t_rttmin;		/* minimum rtt allowed */
	u_long	max_sndwnd;		/* largest window peer has offered */

/* out-of-band data */
	char	t_oobflags;		/* have some */
	char	t_iobc;			/* input character */
#define	TCPOOB_HAVEDATA	0x01
#define	TCPOOB_HADDATA	0x02
	short	t_softerror;		/* possible error not yet reported */

/* RFC 1323 variables */
	u_char	snd_scale;		/* window scaling for send window */
	u_char	rcv_scale;		/* window scaling for recv window */
	u_char	request_r_scale;	/* pending window scaling */
	u_char	requested_s_scale;
	u_int32_t ts_recent;		/* timestamp echo data */
	u_int32_t ts_recent_age;	/* when last updated */
	u_int32_t ts_timebase;		/* our timebase */
	tcp_seq	last_ack_sent;

/* SACK stuff */
	struct ipqehead timeq;		/* time sequenced queue (for SACK) */

/* pointer for syn cache entries*/
	LIST_HEAD(, syn_cache) t_sc;	/* list of entries by this tcb */
};

#ifdef _KERNEL
/*
 * TCP reassembly queue locks.
 */
static __inline int tcp_reass_lock_try __P((struct tcpcb *))
	__attribute__((__unused__));
static __inline void tcp_reass_unlock __P((struct tcpcb *))
	__attribute__((__unused__));

static __inline int
tcp_reass_lock_try(tp)
	struct tcpcb *tp;
{
	int s;

	s = splimp();
	if (tp->t_flags & TF_REASSEMBLING) {
		splx(s);
		return (0);
	}
	tp->t_flags |= TF_REASSEMBLING;
	splx(s);
	return (1);
}

static __inline void
tcp_reass_unlock(tp)
	struct tcpcb *tp;
{
	int s;

	s = splimp();
	tp->t_flags &= ~TF_REASSEMBLING;
	splx(s);
}

#ifdef DIAGNOSTIC
#define	TCP_REASS_LOCK(tp)						\
do {									\
	if (tcp_reass_lock_try(tp) == 0) {				\
		printf("%s:%d: tcpcb %p reass already locked\n",	\
		    __FILE__, __LINE__, tp);				\
		panic("tcp_reass_lock");				\
	}								\
} while (0)
#define	TCP_REASS_LOCK_CHECK(tp)					\
do {									\
	if (((tp)->t_flags & TF_REASSEMBLING) == 0) {			\
		printf("%s:%d: tcpcb %p reass lock not held\n",		\
		    __FILE__, __LINE__, tp);				\
		panic("tcp reass lock check");				\
	}								\
} while (0)
#else
#define	TCP_REASS_LOCK(tp)	(void) tcp_reass_lock_try((tp))
#define	TCP_REASS_LOCK_CHECK(tp) /* nothing */
#endif

#define	TCP_REASS_UNLOCK(tp)	tcp_reass_unlock((tp))
#endif /* _KERNEL */

/*
 * Queue for delayed ACK processing.
 */
LIST_HEAD(tcp_delack_head, tcpcb);
#ifdef _KERNEL
extern struct tcp_delack_head tcp_delacks;

#define	TCP_SET_DELACK(tp) \
do { \
	if (((tp)->t_flags & TF_DELACK) == 0) { \
		(tp)->t_flags |= TF_DELACK; \
		LIST_INSERT_HEAD(&tcp_delacks, (tp), t_delack); \
	} \
} while (0)

#define	TCP_CLEAR_DELACK(tp) \
do { \
	if ((tp)->t_flags & TF_DELACK) { \
		(tp)->t_flags &= ~TF_DELACK; \
		LIST_REMOVE((tp), t_delack); \
	} \
} while (0)
#endif /* _KERNEL */

/*
 * Compute the current timestamp for a connection.
 */
#define	TCP_TIMESTAMP(tp)	(tcp_now - (tp)->ts_timebase)

/*
 * Handy way of passing around TCP option info.
 */
struct tcp_opt_info {
	int		ts_present;
	u_int32_t	ts_val;
	u_int32_t	ts_ecr;
	u_int16_t	maxseg;
};

/*
 * Data for the TCP compressed state engine.
 */
union syn_cache_sa {
	struct sockaddr sa;
	struct sockaddr_in sin;
#if 1 /*def INET6*/
	struct sockaddr_in6 sin6;
#endif
};

struct syn_cache {
	LIST_ENTRY(syn_cache) sc_bucketq;	/* link on bucket list */
	TAILQ_ENTRY(syn_cache) sc_timeq;	/* link on timer queue */
	union {					/* cached route */
		struct route route4;
#ifdef INET6
		struct route_in6 route6;
#endif
	} sc_route_u;
#define sc_route4	sc_route_u.route4
#ifdef INET6
#define sc_route6	sc_route_u.route6
#endif
	long sc_win;				/* advertised window */
	int sc_bucketidx;			/* our bucket index */
	u_int32_t sc_hash;
	u_int32_t sc_timestamp;			/* timestamp from SYN */
	u_int32_t sc_timebase;			/* our local timebase */
	union syn_cache_sa sc_src;
	union syn_cache_sa sc_dst;
	tcp_seq sc_irs;
	tcp_seq sc_iss;
	u_int sc_rexmt;				/* retransmit timer */
	u_int sc_rxtcur;			/* current rxt timeout */
	u_int sc_rxttot;			/* total time spend on queues */
	u_short sc_rxtshift;			/* for computing backoff */
	u_short sc_flags;

#define	SCF_UNREACH		0x0001		/* we've had an unreach error */
#define	SCF_TIMESTAMP		0x0002		/* peer will do timestamps */

	struct mbuf *sc_ipopts;			/* IP options */
	u_int16_t sc_peermaxseg;
	u_int16_t sc_ourmaxseg;
	u_int8_t sc_request_r_scale	: 4,
		 sc_requested_s_scale	: 4;

	struct tcpcb *sc_tp;			/* tcb for listening socket */
	LIST_ENTRY(syn_cache) sc_tpq;		/* list of entries by same tp */
};

struct syn_cache_head {
	LIST_HEAD(, syn_cache) sch_bucket;	/* bucket entries */
	u_short sch_length;			/* # entries in bucket */
};

#define	intotcpcb(ip)	((struct tcpcb *)(ip)->inp_ppcb)
#ifdef INET6
#define	in6totcpcb(ip)	((struct tcpcb *)(ip)->in6p_ppcb)
#endif
#ifndef INET6
#define	sototcpcb(so)	(intotcpcb(sotoinpcb(so)))
#else
#define	sototcpcb(so)	(((so)->so_proto->pr_domain->dom_family == AF_INET) \
				? intotcpcb(sotoinpcb(so)) \
				: in6totcpcb(sotoin6pcb(so)))
#endif

/*
 * The smoothed round-trip time and estimated variance
 * are stored as fixed point numbers scaled by the values below.
 * For convenience, these scales are also used in smoothing the average
 * (smoothed = (1/scale)sample + ((scale-1)/scale)smoothed).
 * With these scales, srtt has 3 bits to the right of the binary point,
 * and thus an "ALPHA" of 0.875.  rttvar has 2 bits to the right of the
 * binary point, and is smoothed with an ALPHA of 0.75.
 */
#define	TCP_RTT_SHIFT		3	/* shift for srtt; 3 bits frac. */
#define	TCP_RTTVAR_SHIFT	2	/* multiplier for rttvar; 2 bits */

/*
 * The initial retransmission 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).
 * This macro assumes that the value of 1<<TCP_RTTVAR_SHIFT
 * is the same as the multiplier for rttvar.
 */
#define	TCP_REXMTVAL(tp) \
	((((tp)->t_srtt >> TCP_RTT_SHIFT) + (tp)->t_rttvar) >> 2)

/*
 * Compute the initial window for slow start.
 */
#define	TCP_INITIAL_WINDOW(iw, segsz) \
	(((iw) == 0) ? (min(4 * (segsz), max(2 * (segsz), 4380))) : \
	 ((segsz) * (iw)))

/*
 * TCP statistics.
 * Many of these should be kept per connection,
 * but that's inconvenient at the moment.
 */
struct	tcpstat {
	u_quad_t tcps_connattempt;	/* connections initiated */
	u_quad_t tcps_accepts;		/* connections accepted */
	u_quad_t tcps_connects;		/* connections established */
	u_quad_t tcps_drops;		/* connections dropped */
	u_quad_t tcps_conndrops;	/* embryonic connections dropped */
	u_quad_t tcps_closed;		/* conn. closed (includes drops) */
	u_quad_t tcps_segstimed;	/* segs where we tried to get rtt */
	u_quad_t tcps_rttupdated;	/* times we succeeded */
	u_quad_t tcps_delack;		/* delayed acks sent */
	u_quad_t tcps_timeoutdrop;	/* conn. dropped in rxmt timeout */
	u_quad_t tcps_rexmttimeo;	/* retransmit timeouts */
	u_quad_t tcps_persisttimeo;	/* persist timeouts */
	u_quad_t tcps_keeptimeo;	/* keepalive timeouts */
	u_quad_t tcps_keepprobe;	/* keepalive probes sent */
	u_quad_t tcps_keepdrops;	/* connections dropped in keepalive */
	u_quad_t tcps_persistdrops;	/* connections dropped in persist */
	u_quad_t tcps_connsdrained;	/* connections drained due to memory
					   shortage */

	u_quad_t tcps_sndtotal;		/* total packets sent */
	u_quad_t tcps_sndpack;		/* data packets sent */
	u_quad_t tcps_sndbyte;		/* data bytes sent */
	u_quad_t tcps_sndrexmitpack;	/* data packets retransmitted */
	u_quad_t tcps_sndrexmitbyte;	/* data bytes retransmitted */
	u_quad_t tcps_sndacks;		/* ack-only packets sent */
	u_quad_t tcps_sndprobe;		/* window probes sent */
	u_quad_t tcps_sndurg;		/* packets sent with URG only */
	u_quad_t tcps_sndwinup;		/* window update-only packets sent */
	u_quad_t tcps_sndctrl;		/* control (SYN|FIN|RST) packets sent */

	u_quad_t tcps_rcvtotal;		/* total packets received */
	u_quad_t tcps_rcvpack;		/* packets received in sequence */
	u_quad_t tcps_rcvbyte;		/* bytes received in sequence */
	u_quad_t tcps_rcvbadsum;	/* packets received with ccksum errs */
	u_quad_t tcps_rcvbadoff;	/* packets received with bad offset */
	u_quad_t tcps_rcvmemdrop;	/* packets dropped for lack of memory */
	u_quad_t tcps_rcvshort;		/* packets received too short */
	u_quad_t tcps_rcvduppack;	/* duplicate-only packets received */
	u_quad_t tcps_rcvdupbyte;	/* duplicate-only bytes received */
	u_quad_t tcps_rcvpartduppack;	/* packets with some duplicate data */
	u_quad_t tcps_rcvpartdupbyte;	/* dup. bytes in part-dup. packets */
	u_quad_t tcps_rcvoopack;	/* out-of-order packets received */
	u_quad_t tcps_rcvoobyte;	/* out-of-order bytes received */
	u_quad_t tcps_rcvpackafterwin;	/* packets with data after window */
	u_quad_t tcps_rcvbyteafterwin;	/* bytes rcvd after window */
	u_quad_t tcps_rcvafterclose;	/* packets rcvd after "close" */
	u_quad_t tcps_rcvwinprobe;	/* rcvd window probe packets */
	u_quad_t tcps_rcvdupack;	/* rcvd duplicate acks */
	u_quad_t tcps_rcvacktoomuch;	/* rcvd acks for unsent data */
	u_quad_t tcps_rcvackpack;	/* rcvd ack packets */
	u_quad_t tcps_rcvackbyte;	/* bytes acked by rcvd acks */
	u_quad_t tcps_rcvwinupd;	/* rcvd window update packets */
	u_quad_t tcps_pawsdrop;		/* segments dropped due to PAWS */
	u_quad_t tcps_predack;		/* times hdr predict ok for acks */
	u_quad_t tcps_preddat;		/* times hdr predict ok for data pkts */

	u_quad_t tcps_pcbhashmiss;	/* input packets missing pcb hash */
	u_quad_t tcps_noport;		/* no socket on port */
	u_quad_t tcps_badsyn;		/* received ack for which we have
					   no SYN in compressed state */

	/* These statistics deal with the SYN cache. */
	u_quad_t tcps_sc_added;		/* # of entries added */
	u_quad_t tcps_sc_completed;	/* # of connections completed */
	u_quad_t tcps_sc_timed_out;	/* # of entries timed out */
	u_quad_t tcps_sc_overflowed;	/* # dropped due to overflow */
	u_quad_t tcps_sc_reset;		/* # dropped due to RST */
	u_quad_t tcps_sc_unreach;	/* # dropped due to ICMP unreach */
	u_quad_t tcps_sc_bucketoverflow;/* # dropped due to bucket overflow */
	u_quad_t tcps_sc_aborted;	/* # of entries aborted (no mem) */
	u_quad_t tcps_sc_dupesyn;	/* # of duplicate SYNs received */
	u_quad_t tcps_sc_dropped;	/* # of SYNs dropped (no route/mem) */
	u_quad_t tcps_sc_collisions;	/* # of hash collisions */
	u_quad_t tcps_sc_retransmitted;	/* # of retransmissions */
};

/*
 * Names for TCP sysctl objects.
 */
#define	TCPCTL_RFC1323		1	/* RFC1323 timestamps/scaling */
#define	TCPCTL_SENDSPACE	2	/* default send buffer */
#define	TCPCTL_RECVSPACE	3	/* default recv buffer */
#define	TCPCTL_MSSDFLT		4	/* default seg size */
#define	TCPCTL_SYN_CACHE_LIMIT	5	/* max size of comp. state engine */
#define	TCPCTL_SYN_BUCKET_LIMIT	6	/* max size of hash bucket */
#define	TCPCTL_SYN_CACHE_INTER	7	/* interval of comp. state timer */
#define	TCPCTL_INIT_WIN		8	/* initial window */
#define	TCPCTL_MSS_IFMTU	9	/* mss from interface, not in_maxmtu */
#define	TCPCTL_SACK		10	/* RFC2018 selective acknowledgement */
#define	TCPCTL_WSCALE		11	/* RFC1323 window scaling */
#define	TCPCTL_TSTAMP		12	/* RFC1323 timestamps */
#define	TCPCTL_COMPAT_42	13	/* 4.2BSD TCP bug work-arounds */
#define	TCPCTL_CWM		14	/* Congestion Window Monitoring */
#define	TCPCTL_CWM_BURSTSIZE	15	/* burst size allowed by CWM */
#define	TCPCTL_ACK_ON_PUSH	16	/* ACK immediately on PUSH */
#define	TCPCTL_KEEPIDLE		17	/* keepalive idle time */
#define	TCPCTL_KEEPINTVL	18	/* keepalive probe interval */
#define	TCPCTL_KEEPCNT		19	/* keepalive count */
#define	TCPCTL_SLOWHZ		20	/* PR_SLOWHZ (read-only) */
#define	TCPCTL_NEWRENO		21	/* NewReno Congestion Control */
#define TCPCTL_LOG_REFUSED	22	/* Log refused connections */
#if 0	/*obsoleted*/
#define	TCPCTL_RSTRATELIMIT	23	/* RST rate limit */
#endif
#define	TCPCTL_RSTPPSLIMIT	24	/* RST pps limit */
#define	TCPCTL_MAXID		25

#define	TCPCTL_NAMES { \
	{ 0, 0 }, \
	{ "rfc1323",	CTLTYPE_INT }, \
	{ "sendspace",	CTLTYPE_INT }, \
	{ "recvspace",	CTLTYPE_INT }, \
	{ "mssdflt",	CTLTYPE_INT }, \
	{ "syn_cache_limit", CTLTYPE_INT }, \
	{ "syn_bucket_limit", CTLTYPE_INT }, \
	{ "syn_cache_interval", CTLTYPE_INT },\
	{ "init_win", CTLTYPE_INT }, \
	{ "mss_ifmtu", CTLTYPE_INT }, \
	{ "sack", CTLTYPE_INT }, \
	{ "win_scale", CTLTYPE_INT }, \
	{ "timestamps", CTLTYPE_INT }, \
	{ "compat_42", CTLTYPE_INT }, \
	{ "cwm", CTLTYPE_INT }, \
	{ "cwm_burstsize", CTLTYPE_INT }, \
	{ "ack_on_push", CTLTYPE_INT }, \
	{ "keepidle",	CTLTYPE_INT }, \
	{ "keepintvl",	CTLTYPE_INT }, \
	{ "keepcnt",	CTLTYPE_INT }, \
	{ "slowhz",	CTLTYPE_INT }, \
	{ "newreno",	CTLTYPE_INT }, \
	{ "log_refused",CTLTYPE_INT }, \
	{ 0, 0 }, \
	{ "rstppslimit", CTLTYPE_INT }, \
}

#ifdef _KERNEL
struct	inpcbtable tcbtable;	/* head of queue of active tcpcb's */
#ifdef INET6
extern struct in6pcb tcb6;
#endif
struct	tcpstat tcpstat;	/* tcp statistics */
u_int32_t tcp_now;		/* for RFC 1323 timestamps */
extern	int tcp_do_rfc1323;	/* enabled/disabled? */
extern	int tcp_do_sack;	/* SACK enabled/disabled? */
extern	int tcp_do_win_scale;	/* RFC1323 window scaling enabled/disabled? */
extern	int tcp_do_timestamps;	/* RFC1323 timestamps enabled/disabled? */
extern	int tcp_do_newreno;	/* Use the New Reno algorithms */
extern	int tcp_mssdflt;	/* default seg size */
extern	int tcp_init_win;	/* initial window */
extern	int tcp_mss_ifmtu;	/* take MSS from interface, not in_maxmtu */
extern	int tcp_compat_42;	/* work around ancient broken TCP peers */
extern	int tcp_cwm;		/* enable Congestion Window Monitoring */
extern	int tcp_cwm_burstsize;	/* burst size allowed by CWM */
extern	int tcp_ack_on_push;	/* ACK immediately on PUSH */
extern	int tcp_syn_cache_limit; /* max entries for compressed state engine */
extern	int tcp_syn_bucket_limit;/* max entries per hash bucket */
extern	int tcp_syn_cache_interval; /* compressed state timer */
extern	int tcp_log_refused;	/* log refused connections */

extern	int tcp_rst_ppslim;

extern	int tcp_syn_cache_size;
extern	struct syn_cache_head tcp_syn_cache[];
extern	u_long syn_cache_count;

#define	TCPCTL_VARIABLES { \
	{ 0 },					\
	{ 1, 0, &tcp_do_rfc1323 },		\
	{ 1, 0, &tcp_sendspace },		\
	{ 1, 0, &tcp_recvspace },		\
	{ 1, 0, &tcp_mssdflt },			\
	{ 1, 0, &tcp_syn_cache_limit },		\
	{ 1, 0, &tcp_syn_bucket_limit },	\
	{ 1, 0, &tcp_syn_cache_interval },	\
	{ 1, 0, &tcp_init_win },		\
	{ 1, 0, &tcp_mss_ifmtu },		\
	{ 1, 0, &tcp_do_sack },			\
	{ 1, 0, &tcp_do_win_scale },		\
	{ 1, 0, &tcp_do_timestamps },		\
	{ 1, 0, &tcp_compat_42 },		\
	{ 1, 0, &tcp_cwm },			\
	{ 1, 0, &tcp_cwm_burstsize },		\
	{ 1, 0, &tcp_ack_on_push },		\
	{ 1, 0, &tcp_keepidle },		\
	{ 1, 0, &tcp_keepintvl },		\
	{ 1, 0, &tcp_keepcnt },			\
	{ 1, 1, 0, PR_SLOWHZ },			\
	{ 1, 0, &tcp_do_newreno },		\
	{ 1, 0, &tcp_log_refused },		\
	{ 0 },					\
	{ 1, 0, &tcp_rst_ppslim },		\
}

int	 tcp_attach __P((struct socket *));
void	 tcp_canceltimers __P((struct tcpcb *));
struct tcpcb *
	 tcp_close __P((struct tcpcb *));
#ifdef INET6
void	 tcp6_ctlinput __P((int, struct sockaddr *, void *));
#endif
void	 *tcp_ctlinput __P((int, struct sockaddr *, void *));
int	 tcp_ctloutput __P((int, struct socket *, int, int, struct mbuf **));
struct tcpcb *
	 tcp_disconnect __P((struct tcpcb *));
struct tcpcb *
	 tcp_drop __P((struct tcpcb *, int));
void	 tcp_dooptions __P((struct tcpcb *,
	    u_char *, int, struct tcphdr *, struct tcp_opt_info *));
void	 tcp_drain __P((void));
void	 tcp_established __P((struct tcpcb *));
void	 tcp_fasttimo __P((void));
void	 tcp_init __P((void));
#ifdef INET6
int	 tcp6_input __P((struct mbuf **, int *, int));
#endif
void	 tcp_input __P((struct mbuf *, ...));
u_long	 tcp_mss_to_advertise __P((const struct ifnet *, int));
void	 tcp_mss_from_peer __P((struct tcpcb *, int));
struct tcpcb *
	 tcp_newtcpcb __P((int, void *));
void	 tcp_notify __P((struct inpcb *, int));
#ifdef INET6
void	 tcp6_notify __P((struct in6pcb *, int));
#endif
u_int	 tcp_optlen __P((struct tcpcb *));
int	 tcp_output __P((struct tcpcb *));
void	 tcp_pulloutofband __P((struct socket *,
	    struct tcphdr *, struct mbuf *, int));
void	 tcp_quench __P((struct inpcb *, int));
#ifdef INET6
void	 tcp6_quench __P((struct in6pcb *, int));
#endif
int	 tcp_reass __P((struct tcpcb *, struct tcphdr *, struct mbuf *, int *));
int	 tcp_respond __P((struct tcpcb *, struct mbuf *, struct mbuf *,
	    struct tcphdr *, tcp_seq, tcp_seq, int));
void	 tcp_rmx_rtt __P((struct tcpcb *));
void	 tcp_setpersist __P((struct tcpcb *));
void	 tcp_slowtimo __P((void));
struct mbuf *
	 tcp_template __P((struct tcpcb *));
struct tcpcb *
	 tcp_timers __P((struct tcpcb *, int));
void	 tcp_trace __P((int, int, struct tcpcb *, struct mbuf *, int));
struct tcpcb *
	 tcp_usrclosed __P((struct tcpcb *));
int	 tcp_sysctl __P((int *, u_int, void *, size_t *, void *, size_t));
int	 tcp_usrreq __P((struct socket *,
	    int, struct mbuf *, struct mbuf *, struct mbuf *, struct proc *));
void	 tcp_xmit_timer __P((struct tcpcb *, int));
tcp_seq	 tcp_new_iss __P((struct tcpcb *, tcp_seq));
tcp_seq  tcp_new_iss1 __P((void *, void *, u_int16_t, u_int16_t, size_t,
	    tcp_seq));

int	 syn_cache_add __P((struct sockaddr *, struct sockaddr *,
		struct tcphdr *, unsigned int, struct socket *,
		struct mbuf *, u_char *, int, struct tcp_opt_info *));
void	 syn_cache_unreach __P((struct sockaddr *, struct sockaddr *,
	   struct tcphdr *));
struct socket *syn_cache_get __P((struct sockaddr *, struct sockaddr *,
		struct tcphdr *, unsigned int, unsigned int,
		struct socket *so, struct mbuf *));
void	 syn_cache_init __P((void));
void	 syn_cache_insert __P((struct syn_cache *, struct tcpcb *));
struct syn_cache *syn_cache_lookup __P((struct sockaddr *, struct sockaddr *,
		struct syn_cache_head **));
void	 syn_cache_reset __P((struct sockaddr *, struct sockaddr *,
		struct tcphdr *));
int	 syn_cache_respond __P((struct syn_cache *, struct mbuf *));
void	 syn_cache_timer __P((void));
void	 syn_cache_cleanup __P((struct tcpcb *));

int	tcp_newreno __P((struct tcpcb *, struct tcphdr *));
#endif

#endif /* _NETINET_TCP_VAR_H_ */