//==========================================================================
//
//      sys/netinet/tcp_usrreq.c
//
//     
//
//==========================================================================
//####COPYRIGHTBEGIN####
//                                                                          
// -------------------------------------------                              
// The contents of this file are subject to the Red Hat eCos Public License 
// Version 1.1 (the "License"); you may not use this file except in         
// compliance with the License.  You may obtain a copy of the License at    
// http://www.redhat.com/                                                   
//                                                                          
// Software distributed under the License is distributed on an "AS IS"      
// basis, WITHOUT WARRANTY OF ANY KIND, either express or implied.  See the 
// License for the specific language governing rights and limitations under 
// the License.                                                             
//                                                                          
// The Original Code is eCos - Embedded Configurable Operating System,      
// released September 30, 1998.                                             
//                                                                          
// The Initial Developer of the Original Code is Red Hat.                   
// Portions created by Red Hat are                                          
// Copyright (C) 1998, 1999, 2000 Red Hat, Inc.                             
// All Rights Reserved.                                                     
// -------------------------------------------                              
//                                                                          
//####COPYRIGHTEND####
//####BSDCOPYRIGHTBEGIN####
//
// -------------------------------------------
//
// Portions of this software may have been derived from OpenBSD or other sources,
// and are covered by the appropriate copyright disclaimers included herein.
//
// -------------------------------------------
//
//####BSDCOPYRIGHTEND####
//==========================================================================
//#####DESCRIPTIONBEGIN####
//
// Author(s):    gthomas
// Contributors: gthomas
// Date:         2000-01-10
// Purpose:      
// Description:  
//              
//
//####DESCRIPTIONEND####
//
//==========================================================================


/*	$OpenBSD: tcp_usrreq.c,v 1.37 1999/12/08 06:50:20 itojun Exp $	*/
/*	$NetBSD: tcp_usrreq.c,v 1.20 1996/02/13 23:44:16 christos Exp $	*/

/*
 * Copyright (c) 1982, 1986, 1988, 1993
 *	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_usrreq.c	8.2 (Berkeley) 1/3/94
 */

/*
%%% portions-copyright-nrl-95
Portions of this software are Copyright 1995-1998 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@ipv6.nrl.navy.mil>.
*/

#include <sys/param.h>
#ifndef __ECOS
#include <sys/systm.h>
#endif
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/protosw.h>
#include <sys/errno.h>
#ifndef __ECOS
#include <sys/stat.h>
#include <sys/proc.h>
#include <sys/ucred.h>

#include <vm/vm.h>
#include <sys/sysctl.h>
#endif

#include <net/if.h>
#include <net/route.h>

#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/in_var.h>
#include <netinet/ip.h>
#include <netinet/in_pcb.h>
#include <netinet/ip_var.h>
#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>
#ifndef __ECOS
#include <dev/rndvar.h>
#endif

#ifdef IPSEC
extern int	check_ipsec_policy __P((struct inpcb *, u_int32_t));
#endif

#ifdef INET6
#include <sys/domain.h>
#endif /* INET6 */

/*
 * TCP protocol interface to socket abstraction.
 */
extern	char *tcpstates[];
extern	int tcptv_keep_init;

/* from in_pcb.c */
extern	struct baddynamicports baddynamicports;

int tcp_ident __P((void *, size_t *, void *, size_t));

#if defined(INET6) && !defined(TCP6)
int
tcp6_usrreq(so, req, m, nam, control, p)
	struct socket *so;
	int req;
	struct mbuf *m, *nam, *control;
	struct proc *p;
{
	return tcp_usrreq(so, req, m, nam, control);
}
#endif

/*
 * Process a TCP user request for TCP tb.  If this is a send request
 * then m is the mbuf chain of send data.  If this is a timer expiration
 * (called from the software clock routine), then timertype tells which timer.
 */
/*ARGSUSED*/
int
tcp_usrreq(so, req, m, nam, control)
	struct socket *so;
	int req;
	struct mbuf *m, *nam, *control;
{
	struct sockaddr_in *sin;
	register struct inpcb *inp;
	register struct tcpcb *tp = NULL;
	int s;
	int error = 0;
	int ostate;

	if (req == PRU_CONTROL) {
#ifdef INET6
		if (sotopf(so) == PF_INET6)
			return in6_control(so, (u_long)m, (caddr_t)nam,
			    (struct ifnet *)control, 0);
		else
#endif /* INET6 */
			return (in_control(so, (u_long)m, (caddr_t)nam,
			    (struct ifnet *)control));
	}
	if (control && control->m_len) {
		m_freem(control);
		if (m)
			m_freem(m);
		return (EINVAL);
	}

	s = splsoftnet();
	inp = sotoinpcb(so);
	/*
	 * When a TCP is attached to a socket, then there will be
	 * a (struct inpcb) pointed at by the socket, and this
	 * structure will point at a subsidary (struct tcpcb).
	 */
	if (inp == 0 && req != PRU_ATTACH) {
		splx(s);
		/*
		 * The following corrects an mbuf leak under rare
		 * circumstances
		 */
		if (m && (req == PRU_SEND || req == PRU_SENDOOB))
			m_freem(m);
		return (EINVAL);		/* XXX */
	}
	if (inp) {
		tp = intotcpcb(inp);
		/* WHAT IF TP IS 0? */
#ifdef KPROF
		tcp_acounts[tp->t_state][req]++;
#endif
		ostate = tp->t_state;
	} else
		ostate = 0;
	switch (req) {

	/*
	 * TCP attaches to socket via PRU_ATTACH, reserving space,
	 * and an internet control block.
	 */
	case PRU_ATTACH:
		if (inp) {
			error = EISCONN;
			break;
		}
		error = tcp_attach(so);
		if (error)
			break;
		if ((so->so_options & SO_LINGER) && so->so_linger == 0)
			so->so_linger = TCP_LINGERTIME;
		tp = sototcpcb(so);
		break;

	/*
	 * PRU_DETACH detaches the TCP protocol from the socket.
	 * If the protocol state is non-embryonic, then can't
	 * do this directly: have to initiate a PRU_DISCONNECT,
	 * which may finish later; embryonic TCB's can just
	 * be discarded here.
	 */
	case PRU_DETACH:
		tp = tcp_disconnect(tp);
		break;

	/*
	 * Give the socket an address.
	 */
	case PRU_BIND:
#ifdef INET6
		if (inp->inp_flags & INP_IPV6)
			error = in6_pcbbind(inp, nam);
		else
#endif
			error = in_pcbbind(inp, nam);
		if (error)
			break;
#ifdef INET6
		/*
		 * If we bind to an address, set up the tp->pf accordingly!
		 */
		if (inp->inp_flags & INP_IPV6) {
			/* If a PF_INET6 socket... */
			if (inp->inp_flags & INP_IPV6_MAPPED)
				tp->pf = AF_INET;
			else if ((inp->inp_flags & INP_IPV6_UNDEC) == 0)
				tp->pf = AF_INET6;
			/* else tp->pf is still 0. */
		}
		/* else socket is PF_INET, and tp->pf is PF_INET. */
#endif /* INET6 */
		break;

	/*
	 * Prepare to accept connections.
	 */
	case PRU_LISTEN:
		if (inp->inp_lport == 0) {
#ifdef INET6
			if (inp->inp_flags & INP_IPV6)
				error = in6_pcbbind(inp, NULL);
			else
#endif
				error = in_pcbbind(inp, NULL);
		}
		/* If the in_pcbbind() above is called, the tp->pf
		   should still be whatever it was before. */
		if (error == 0)
			tp->t_state = TCPS_LISTEN;
		break;

	/*
	 * Initiate connection to peer.
	 * Create a template for use in transmissions on this connection.
	 * Enter SYN_SENT state, and mark socket as connecting.
	 * Start keep-alive timer, and seed output sequence space.
	 * Send initial segment on connection.
	 */
	case PRU_CONNECT:
		sin = mtod(nam, struct sockaddr_in *);

#ifdef INET6
		if (sin->sin_family == AF_INET6) {
			struct in6_addr *in6_addr = &mtod(nam,
			    struct sockaddr_in6 *)->sin6_addr;

			if (IN6_IS_ADDR_UNSPECIFIED(in6_addr) ||
			    IN6_IS_ADDR_MULTICAST(in6_addr) ||
			    (IN6_IS_ADDR_V4MAPPED(in6_addr) &&
			    ((in6_addr->s6_addr32[3] == INADDR_ANY) ||
			    IN_MULTICAST(in6_addr->s6_addr32[3]) ||
			    in_broadcast(sin->sin_addr, NULL)))) {
				error = EINVAL;
				break;
			}

			if (inp->inp_lport == 0) {
				error = in6_pcbbind(inp, NULL);
				if (error)
					break;
			}
			error = in6_pcbconnect(inp, nam);
		} else if (sin->sin_family == AF_INET)
#endif /* INET6 */
		{
			if ((sin->sin_addr.s_addr == INADDR_ANY) ||
			    IN_MULTICAST(sin->sin_addr.s_addr) ||
			    in_broadcast(sin->sin_addr, NULL)) {
				error = EINVAL;
				break;
			}

			/* Trying to connect to some broadcast address */
			if (in_broadcast(sin->sin_addr, NULL)) {
				error = EINVAL;
				break;
			}

			if (inp->inp_lport == 0) {
				error = in_pcbbind(inp, NULL);
				if (error)
					break;
			}
			error = in_pcbconnect(inp, nam);
		}

		if (error)
			break;

#ifdef INET6
		/*
		 * With a connection, I now know the version of IP
		 * is in use and hence can set tp->pf with authority. 
		 */
		if (inp->inp_flags & INP_IPV6) {
			if (inp->inp_flags & INP_IPV6_MAPPED)
				tp->pf = PF_INET;
			else
				tp->pf = PF_INET6;
		}
		/* else I'm a PF_INET socket, and hence tp->pf is PF_INET. */
#endif /* INET6 */

		tp->t_template = tcp_template(tp);
		if (tp->t_template == 0) {
			in_pcbdisconnect(inp);
			error = ENOBUFS;
			break;
		}

#ifdef INET6
		if ((inp->inp_flags & INP_IPV6) && (tp->pf == PF_INET)) {
			inp->inp_ip.ip_ttl = ip_defttl;
			inp->inp_ip.ip_tos = 0;
		}
#endif /* INET6 */

		so->so_state |= SS_CONNECTOUT;
		/* Compute window scaling to request.  */
		while (tp->request_r_scale < TCP_MAX_WINSHIFT &&
		    (TCP_MAXWIN << tp->request_r_scale) < so->so_rcv.sb_hiwat)
			tp->request_r_scale++;
		soisconnecting(so);
		tcpstat.tcps_connattempt++;
		tp->t_state = TCPS_SYN_SENT;
		tp->t_timer[TCPT_KEEP] = tcptv_keep_init;
		tp->iss = tcp_iss;
#ifdef TCP_COMPAT_42
		tcp_iss += TCP_ISSINCR/2;
#else /* TCP_COMPAT_42 */
		tcp_iss += arc4random() % TCP_ISSINCR + 1;
#endif /* !TCP_COMPAT_42 */
		tcp_sendseqinit(tp);
#if defined(TCP_SACK) || defined(TCP_NEWRENO)
		tp->snd_last = tp->snd_una;
#endif
#if defined(TCP_SACK) && defined(TCP_FACK)
		tp->snd_fack = tp->snd_una;
		tp->retran_data = 0;
		tp->snd_awnd = 0;
#endif
		error = tcp_output(tp);
		break;

	/*
	 * Create a TCP connection between two sockets.
	 */
	case PRU_CONNECT2:
		error = EOPNOTSUPP;
		break;

	/*
	 * Initiate disconnect from peer.
	 * If connection never passed embryonic stage, just drop;
	 * else if don't need to let data drain, then can just drop anyways,
	 * else have to begin TCP shutdown process: mark socket disconnecting,
	 * drain unread data, state switch to reflect user close, and
	 * send segment (e.g. FIN) to peer.  Socket will be really disconnected
	 * when peer sends FIN and acks ours.
	 *
	 * SHOULD IMPLEMENT LATER PRU_CONNECT VIA REALLOC TCPCB.
	 */
	case PRU_DISCONNECT:
		tp = tcp_disconnect(tp);
		break;

	/*
	 * Accept a connection.  Essentially all the work is
	 * done at higher levels; just return the address
	 * of the peer, storing through addr.
	 */
	case PRU_ACCEPT:
#ifdef INET6
		if (inp->inp_flags & INP_IPV6)
			in6_setpeeraddr(inp, nam);
		else
#endif
			in_setpeeraddr(inp, nam);
		break;

	/*
	 * Mark the connection as being incapable of further output.
	 */
	case PRU_SHUTDOWN:
		if (so->so_state & SS_CANTSENDMORE)
			break;
		socantsendmore(so);
		tp = tcp_usrclosed(tp);
		if (tp)
			error = tcp_output(tp);
		break;

	/*
	 * After a receive, possibly send window update to peer.
	 */
	case PRU_RCVD:
		(void) tcp_output(tp);
		break;

	/*
	 * Do a send by putting data in output queue and updating urgent
	 * marker if URG set.  Possibly send more data.
	 */
	case PRU_SEND:
#ifdef IPSEC
		error = check_ipsec_policy(inp, 0);
		if (error)
			break;
#endif
		sbappend(&so->so_snd, m);
		error = tcp_output(tp);
		break;

	/*
	 * Abort the TCP.
	 */
	case PRU_ABORT:
		tp = tcp_drop(tp, ECONNABORTED);
		break;

#ifndef __ECOS
	case PRU_SENSE:
		((struct stat *) m)->st_blksize = so->so_snd.sb_hiwat;
		(void) splx(s);
		return (0);
#endif

	case PRU_RCVOOB:
		if ((so->so_oobmark == 0 &&
		    (so->so_state & SS_RCVATMARK) == 0) ||
		    so->so_options & SO_OOBINLINE ||
		    tp->t_oobflags & TCPOOB_HADDATA) {
			error = EINVAL;
			break;
		}
		if ((tp->t_oobflags & TCPOOB_HAVEDATA) == 0) {
			error = EWOULDBLOCK;
			break;
		}
		m->m_len = 1;
		*mtod(m, caddr_t) = tp->t_iobc;
		if (((long)nam & MSG_PEEK) == 0)
			tp->t_oobflags ^= (TCPOOB_HAVEDATA | TCPOOB_HADDATA);
		break;

	case PRU_SENDOOB:
		if (sbspace(&so->so_snd) < -512) {
			m_freem(m);
			error = ENOBUFS;
			break;
		}
		/*
		 * 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.
		 * Otherwise, snd_up should be one lower.
		 */
		sbappend(&so->so_snd, m);
		tp->snd_up = tp->snd_una + so->so_snd.sb_cc;
		tp->t_force = 1;
		error = tcp_output(tp);
		tp->t_force = 0;
		break;

	case PRU_SOCKADDR:
#ifdef INET6
		if (inp->inp_flags & INP_IPV6)
			in6_setsockaddr(inp, nam);
		else
#endif
			in_setsockaddr(inp, nam);
		break;

	case PRU_PEERADDR:
#ifdef INET6
		if (inp->inp_flags & INP_IPV6)
			in6_setpeeraddr(inp, nam);
		else
#endif
			in_setpeeraddr(inp, nam);
		break;

	/*
	 * TCP slow timer went off; going through this
	 * routine for tracing's sake.
	 */
	case PRU_SLOWTIMO:
		tp = tcp_timers(tp, (long)nam);
		req |= (long)nam << 8;		/* for debug's sake */
		break;

	default:
		panic("tcp_usrreq");
	}
	if (tp && (so->so_options & SO_DEBUG))
		tcp_trace(TA_USER, ostate, tp, (caddr_t)0, req, 0);
	splx(s);
	return (error);
}

int
tcp_ctloutput(op, so, level, optname, mp)
	int op;
	struct socket *so;
	int level, optname;
	struct mbuf **mp;
{
	int error = 0, s;
	struct inpcb *inp;
	register struct tcpcb *tp;
	register struct mbuf *m;
	register int i;

	s = splsoftnet();
	inp = sotoinpcb(so);
	if (inp == NULL) {
		splx(s);
		if (op == PRCO_SETOPT && *mp)
			(void) m_free(*mp);
		return (ECONNRESET);
	}
#ifdef INET6
	tp = intotcpcb(inp);
#endif /* INET6 */
	if (level != IPPROTO_TCP) {
#ifdef INET6
		/*
		 * Not sure if this is the best approach.
		 * It seems to be, but we don't set tp->pf until the connection
		 * is established, which may lead to confusion in the case of
		 * AF_INET6 sockets which get SET/GET options for IPv4.
		 */
		if (tp->pf == PF_INET6)
			error = ip6_ctloutput(op, so, level, optname, mp);
		else
#endif /* INET6 */
			error = ip_ctloutput(op, so, level, optname, mp);
		splx(s);
		return (error);
	}
#ifndef INET6
	tp = intotcpcb(inp);
#endif /* !INET6 */

	switch (op) {

	case PRCO_SETOPT:
		m = *mp;
		switch (optname) {

		case TCP_NODELAY:
			if (m == NULL || m->m_len < sizeof (int))
				error = EINVAL;
			else if (*mtod(m, int *))
				tp->t_flags |= TF_NODELAY;
			else
				tp->t_flags &= ~TF_NODELAY;
			break;

		case TCP_MAXSEG:
			if (m == NULL || m->m_len < sizeof (int)) {
				error = EINVAL;
				break;
			}

			i = *mtod(m, int *);
			if (i > 0 && i <= tp->t_maxseg)
				tp->t_maxseg = i;
			else
				error = EINVAL;
			break;

#ifdef TCP_SACK
		case TCP_SACK_DISABLE:
			if (m == NULL || m->m_len < sizeof (int)) {
				error = EINVAL;
				break;
			}

			if (TCPS_HAVEESTABLISHED(tp->t_state)) {
				error = EPERM;
				break;
			}

			if (tp->t_flags & TF_SIGNATURE) {
				error = EPERM;
				break;
			}

			if (*mtod(m, int *))
				tp->sack_disable = 1;
			else
				tp->sack_disable = 0;
			break;
#endif
#ifdef TCP_SIGNATURE
		case TCP_SIGNATURE_ENABLE:
			if (m == NULL || m->m_len < sizeof (int)) {
				error = EINVAL;
				break;
			}

			if (TCPS_HAVEESTABLISHED(tp->t_state)) {
				error = EPERM;
				break;
			}

			if (*mtod(m, int *)) {
				tp->t_flags |= TF_SIGNATURE;
#ifdef TCP_SACK
				tp->sack_disable = 1;
#endif /* TCP_SACK */
			} else
				tp->t_flags &= ~TF_SIGNATURE;
			break;
#endif /* TCP_SIGNATURE */
 		default:
			error = ENOPROTOOPT;
			break;
		}
		if (m)
			(void) m_free(m);
		break;

	case PRCO_GETOPT:
		*mp = m = m_get(M_WAIT, MT_SOOPTS);
		m->m_len = sizeof(int);

		switch (optname) {
		case TCP_NODELAY:
			*mtod(m, int *) = tp->t_flags & TF_NODELAY;
			break;
		case TCP_MAXSEG:
			*mtod(m, int *) = tp->t_maxseg;
			break;
#ifdef TCP_SACK
		case TCP_SACK_DISABLE:
			*mtod(m, int *) = tp->sack_disable;
			break;
#endif
		default:
			error = ENOPROTOOPT;
			break;
		}
		break;
	}
	splx(s);
	return (error);
}

#ifndef TCP_SENDSPACE
#define	TCP_SENDSPACE	1024*16;
#endif
u_int	tcp_sendspace = TCP_SENDSPACE;
#ifndef TCP_RECVSPACE
#define	TCP_RECVSPACE	1024*16;
#endif
u_int	tcp_recvspace = TCP_RECVSPACE;

/*
 * Attach TCP protocol to socket, allocating
 * internet protocol control block, tcp control block,
 * bufer space, and entering LISTEN state if to accept connections.
 */
int
tcp_attach(so)
	struct socket *so;
{
	register struct tcpcb *tp;
	struct inpcb *inp;
	int error;

	if (so->so_snd.sb_hiwat == 0 || so->so_rcv.sb_hiwat == 0) {
		error = soreserve(so, tcp_sendspace, tcp_recvspace);
		if (error)
			return (error);
	}
	error = in_pcballoc(so, &tcbtable);
	if (error)
		return (error);
	inp = sotoinpcb(so);
	tp = tcp_newtcpcb(inp);
	if (tp == NULL) {
		int nofd = so->so_state & SS_NOFDREF;	/* XXX */

		so->so_state &= ~SS_NOFDREF;	/* don't free the socket yet */
		in_pcbdetach(inp);
		so->so_state |= nofd;
		return (ENOBUFS);
	}
	tp->t_state = TCPS_CLOSED;
	return (0);
}

/*
 * Initiate (or continue) disconnect.
 * If embryonic state, just send reset (once).
 * If in ``let data drain'' option and linger null, just drop.
 * Otherwise (hard), mark socket disconnecting and drop
 * current input data; switch states based on user close, and
 * send segment to peer (with FIN).
 */
struct tcpcb *
tcp_disconnect(tp)
	register struct tcpcb *tp;
{
	struct socket *so = tp->t_inpcb->inp_socket;

	if (TCPS_HAVEESTABLISHED(tp->t_state) == 0)
		tp = tcp_close(tp);
	else if ((so->so_options & SO_LINGER) && so->so_linger == 0)
		tp = tcp_drop(tp, 0);
	else {
		soisdisconnecting(so);
		sbflush(&so->so_rcv);
		tp = tcp_usrclosed(tp);
		if (tp)
			(void) tcp_output(tp);
	}
	return (tp);
}

/*
 * User issued close, and wish to trail through shutdown states:
 * if never received SYN, just forget it.  If got a SYN from peer,
 * but haven't sent FIN, then go to FIN_WAIT_1 state to send peer a FIN.
 * If already got a FIN from peer, then almost done; go to LAST_ACK
 * state.  In all other cases, have already sent FIN to peer (e.g.
 * after PRU_SHUTDOWN), and just have to play tedious game waiting
 * for peer to send FIN or not respond to keep-alives, etc.
 * We can let the user exit from the close as soon as the FIN is acked.
 */
struct tcpcb *
tcp_usrclosed(tp)
	register struct tcpcb *tp;
{

	switch (tp->t_state) {

	case TCPS_CLOSED:
	case TCPS_LISTEN:
	case TCPS_SYN_SENT:
		tp->t_state = TCPS_CLOSED;
		tp = tcp_close(tp);
		break;

	case TCPS_SYN_RECEIVED:
	case TCPS_ESTABLISHED:
		tp->t_state = TCPS_FIN_WAIT_1;
		break;

	case TCPS_CLOSE_WAIT:
		tp->t_state = TCPS_LAST_ACK;
		break;
	}
	if (tp && tp->t_state >= TCPS_FIN_WAIT_2) {
		soisdisconnected(tp->t_inpcb->inp_socket);
		/*
		 * If we are in FIN_WAIT_2, we arrived here because the
		 * application did a shutdown of the send side.  Like the
		 * case of a transition from FIN_WAIT_1 to FIN_WAIT_2 after
		 * a full close, we start a timer to make sure sockets are
		 * not left in FIN_WAIT_2 forever.
		 */
		if (tp->t_state == TCPS_FIN_WAIT_2)
			tp->t_timer[TCPT_2MSL] = tcp_maxidle;
	}
	return (tp);
}

/*
 * Look up a socket for ident..
 */
int
tcp_ident(oldp, oldlenp, newp, newlen)
	void *oldp;
	size_t *oldlenp;
	void *newp;
	size_t newlen;
{
	int error = 0, s;
	struct tcp_ident_mapping tir;
	struct inpcb *inp;
	struct sockaddr_in *fin, *lin;

	if (oldp == NULL || newp != NULL || newlen != 0)
		return (EINVAL);
	if  (*oldlenp < sizeof(tir))
		return (ENOMEM);
	if ((error = copyin(oldp, &tir, sizeof (tir))) != 0 )
		return (error);
	if (tir.faddr.sa_len != sizeof (struct sockaddr) ||
	    tir.faddr.sa_family != AF_INET)
		return (EINVAL);
	fin = (struct sockaddr_in *)&tir.faddr;
	lin = (struct sockaddr_in *)&tir.laddr;

	s = splsoftnet();
	inp = in_pcbhashlookup(&tcbtable,  fin->sin_addr, fin->sin_port,
	    lin->sin_addr, lin->sin_port);
	if (inp == NULL) {
		++tcpstat.tcps_pcbhashmiss;
		inp = in_pcblookup(&tcbtable, &fin->sin_addr, fin->sin_port,
		    &lin->sin_addr, lin->sin_port, 0);
	}
	if (inp != NULL && (inp->inp_socket->so_state & SS_CONNECTOUT)) {
		tir.ruid = inp->inp_socket->so_ruid;
		tir.euid = inp->inp_socket->so_euid;
	} else {
		tir.ruid = -1;
		tir.euid = -1;
	}
	splx(s);

	*oldlenp = sizeof (tir);
	error = copyout((void *)&tir, oldp, sizeof (tir));
	return (error);
}

#ifdef CYGPKG_NET_SYSCTL
/*
 * Sysctl for tcp variables.
 */
int
tcp_sysctl(name, namelen, oldp, oldlenp, newp, newlen)
	int *name;
	u_int namelen;
	void *oldp;
	size_t *oldlenp;
	void *newp;
	size_t newlen;
{

	/* All sysctl names at this level are terminal. */
	if (namelen != 1)
		return (ENOTDIR);

	switch (name[0]) {
	case TCPCTL_RFC1323:
		return (sysctl_int(oldp, oldlenp, newp, newlen,
		    &tcp_do_rfc1323));
#ifdef TCP_SACK
	case TCPCTL_SACK:
		return (sysctl_int(oldp, oldlenp, newp, newlen,
		    &tcp_do_sack));
#endif
	case TCPCTL_MSSDFLT:
		return (sysctl_int(oldp, oldlenp, newp, newlen,
		    &tcp_mssdflt));
	case TCPCTL_KEEPINITTIME:
		return (sysctl_int(oldp, oldlenp, newp, newlen,
		    &tcptv_keep_init));

	case TCPCTL_KEEPIDLE:
		return (sysctl_int(oldp, oldlenp, newp, newlen,
		    &tcp_keepidle));

	case TCPCTL_KEEPINTVL:
		return (sysctl_int(oldp, oldlenp, newp, newlen,
		    &tcp_keepintvl));

	case TCPCTL_SLOWHZ:
		return (sysctl_rdint(oldp, oldlenp, newp, PR_SLOWHZ));

	case TCPCTL_BADDYNAMIC:
		return (sysctl_struct(oldp, oldlenp, newp, newlen,
		    baddynamicports.tcp, sizeof(baddynamicports.tcp)));

	case TCPCTL_RECVSPACE:
		return (sysctl_int(oldp, oldlenp, newp, newlen,&tcp_recvspace));

	case TCPCTL_SENDSPACE:
		return (sysctl_int(oldp, oldlenp, newp, newlen,&tcp_sendspace));
	case TCPCTL_IDENT:
		return (tcp_ident(oldp, oldlenp, newp, newlen));
	default:
		return (ENOPROTOOPT);
	}
	/* NOTREACHED */
}
#endif // CYGPKG_NET_SYSCTL
