/*

 * Copyright (c) 1982, 1986, 1988, 1990, 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_subr.c	8.1 (Berkeley) 6/10/93

 * tcp_subr.c,v 1.5 1994/10/08 22:39:58 phk Exp

 */

/*

 * Changes and additions relating to SLiRP

 * Copyright (c) 1995 Danny Gasparovski.

 *

 * Please read the file COPYRIGHT for the

 * terms and conditions of the copyright.

 */

#define WANT_SYS_IOCTL_H

#include <slirp.h>

/* patchable/settable parameters for tcp */

/* Don't do rfc1323 performance enhancements */

#define TCP_DO_RFC1323 0

/*

 * Tcp initialization

 */

void

tcp_init()

{

	tcp_iss = 1;		/* wrong */

	tcb.so_next = tcb.so_prev = &tcb;

}

/*

 * Create template to be used to send tcp packets on a connection.

 * Call after host entry created, fills

 * in a skeletal tcp/ip header, minimizing the amount of work

 * necessary when the connection is used.

 */

/* struct tcpiphdr * */

void

tcp_template(tp)

	struct tcpcb *tp;

{

	struct socket *so = tp->t_socket;

	register struct tcpiphdr *n = &tp->t_template;

	n->ti_next = n->ti_prev = 0;

	n->ti_x1 = 0;

	n->ti_pr = IPPROTO_TCP;

	n->ti_len = htons(sizeof (struct tcpiphdr) - sizeof (struct ip));

	n->ti_src = so->so_faddr;

	n->ti_dst = so->so_laddr;

	n->ti_sport = so->so_fport;

	n->ti_dport = so->so_lport;

	n->ti_seq = 0;

	n->ti_ack = 0;

	n->ti_x2 = 0;

	n->ti_off = 5;

	n->ti_flags = 0;

	n->ti_win = 0;

	n->ti_sum = 0;

	n->ti_urp = 0;

}

/*

 * Send a single message to the TCP at address specified by

 * the given TCP/IP header.  If m == 0, then we make a copy

 * of the tcpiphdr at ti and send directly to the addressed host.

 * This is used to force keep alive messages out using the TCP

 * template for a connection tp->t_template.  If flags are given

 * then we send a message back to the TCP which originated the

 * segment ti, and discard the mbuf containing it and any other

 * attached mbufs.

 *

 * In any case the ack and sequence number of the transmitted

 * segment are as specified by the parameters.

 */

void

tcp_respond(tp, ti, m, ack, seq, flags)

	struct tcpcb *tp;

	register struct tcpiphdr *ti;

	register struct mbuf *m;

	tcp_seq ack, seq;

	int flags;

{

	register int tlen;

	int win = 0;

	DEBUG_CALL("tcp_respond");

	DEBUG_ARG("tp = %lx", (long)tp);

	DEBUG_ARG("ti = %lx", (long)ti);

	DEBUG_ARG("m = %lx", (long)m);

	DEBUG_ARG("ack = %u", ack);

	DEBUG_ARG("seq = %u", seq);

	DEBUG_ARG("flags = %x", flags);

	if (tp)

		win = sbspace(&tp->t_socket->so_rcv);

	if (m == 0) {

		if ((m = m_get()) == NULL)

			return;

#ifdef TCP_COMPAT_42

		tlen = 1;

#else

		tlen = 0;

#endif

		m->m_data += IF_MAXLINKHDR;

		*mtod(m, struct tcpiphdr *) = *ti;

		ti = mtod(m, struct tcpiphdr *);

		flags = TH_ACK;

	} else {

		/*

		 * ti points into m so the next line is just making

		 * the mbuf point to ti

		 */

		m->m_data = (caddr_t)ti;

		m->m_len = sizeof (struct tcpiphdr);

		tlen = 0;

#define xchg(a,b,type) { type t; t=a; a=b; b=t; }

		xchg(ti->ti_dst.s_addr, ti->ti_src.s_addr, u_int32_t);

		xchg(ti->ti_dport, ti->ti_sport, u_int16_t);

#undef xchg

	}

	ti->ti_len = htons((u_short)(sizeof (struct tcphdr) + tlen));

	tlen += sizeof (struct tcpiphdr);

	m->m_len = tlen;

	ti->ti_next = ti->ti_prev = 0;

	ti->ti_x1 = 0;

	ti->ti_seq = htonl(seq);

	ti->ti_ack = htonl(ack);

	ti->ti_x2 = 0;

	ti->ti_off = sizeof (struct tcphdr) >> 2;

	ti->ti_flags = flags;

	if (tp)

		ti->ti_win = htons((u_int16_t) (win >> tp->rcv_scale));

	else

		ti->ti_win = htons((u_int16_t)win);

	ti->ti_urp = 0;

	ti->ti_sum = 0;

	ti->ti_sum = cksum(m, tlen);

	((struct ip *)ti)->ip_len = tlen;

	if(flags & TH_RST)

	  ((struct ip *)ti)->ip_ttl = MAXTTL;

	else

	  ((struct ip *)ti)->ip_ttl = IPDEFTTL;

	(void) ip_output((struct socket *)0, m);

}

/*

 * Create a new TCP control block, making an

 * empty reassembly queue and hooking it to the argument

 * protocol control block.

 */

struct tcpcb *

tcp_newtcpcb(so)

	struct socket *so;

{

	register struct tcpcb *tp;

	tp = (struct tcpcb *)malloc(sizeof(*tp));

	if (tp == NULL)

		return ((struct tcpcb *)0);

	memset((char *) tp, 0, sizeof(struct tcpcb));

	tp->seg_next = tp->seg_prev = (tcpiphdrp_32)tp;

	tp->t_maxseg = TCP_MSS;

	tp->t_flags = TCP_DO_RFC1323 ? (TF_REQ_SCALE|TF_REQ_TSTMP) : 0;

	tp->t_socket = so;

	/*

	 * Init srtt to TCPTV_SRTTBASE (0), so we can tell that we have no

	 * rtt estimate.  Set rttvar so that srtt + 2 * rttvar gives

	 * reasonable initial retransmit time.

	 */

	tp->t_srtt = TCPTV_SRTTBASE;

	tp->t_rttvar = TCPTV_SRTTDFLT << 2;

	tp->t_rttmin = TCPTV_MIN;

	TCPT_RANGESET(tp->t_rxtcur,

	    ((TCPTV_SRTTBASE >> 2) + (TCPTV_SRTTDFLT << 2)) >> 1,

	    TCPTV_MIN, TCPTV_REXMTMAX);

	tp->snd_cwnd = TCP_MAXWIN << TCP_MAX_WINSHIFT;

	tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT;

	tp->t_state = TCPS_CLOSED;

	so->so_tcpcb = tp;

	return (tp);

}

/*

 * Drop a TCP connection, reporting

 * the specified error.  If connection is synchronized,

 * then send a RST to peer.

 */

struct tcpcb *tcp_drop(struct tcpcb *tp, int err)

{

/* tcp_drop(tp, errno)

	register struct tcpcb *tp;

	int errno;

{

*/

	DEBUG_CALL("tcp_drop");

	DEBUG_ARG("tp = %lx", (long)tp);

	DEBUG_ARG("errno = %d", errno);

	if (TCPS_HAVERCVDSYN(tp->t_state)) {

		tp->t_state = TCPS_CLOSED;

		(void) tcp_output(tp);

		STAT(tcpstat.tcps_drops++);

	} else

		STAT(tcpstat.tcps_conndrops++);

/*	if (errno == ETIMEDOUT && tp->t_softerror)

 *		errno = tp->t_softerror;

 */

/*	so->so_error = errno; */

	return (tcp_close(tp));

}

/*

 * Close a TCP control block:

 *	discard all space held by the tcp

 *	discard internet protocol block

 *	wake up any sleepers

 */

struct tcpcb *

tcp_close(tp)

	register struct tcpcb *tp;

{

	register struct tcpiphdr *t;

	struct socket *so = tp->t_socket;

	register struct mbuf *m;

	DEBUG_CALL("tcp_close");

	DEBUG_ARG("tp = %lx", (long )tp);

	/* free the reassembly queue, if any */

	t = (struct tcpiphdr *) tp->seg_next;

	while (t != (struct tcpiphdr *)tp) {

		t = (struct tcpiphdr *)t->ti_next;

		m = (struct mbuf *) REASS_MBUF((struct tcpiphdr *)t->ti_prev);

		remque_32((struct tcpiphdr *) t->ti_prev);

		m_freem(m);

	}

	/* It's static */

/*	if (tp->t_template)

 *		(void) m_free(dtom(tp->t_template));

 */

/*	free(tp, M_PCB);  */

	free(tp);

	so->so_tcpcb = 0;

	soisfdisconnected(so);

	/* clobber input socket cache if we're closing the cached connection */

	if (so == tcp_last_so)

		tcp_last_so = &tcb;

	closesocket(so->s);

	sbfree(&so->so_rcv);

	sbfree(&so->so_snd);

	sofree(so);

	STAT(tcpstat.tcps_closed++);

	return ((struct tcpcb *)0);

}

#ifdef notdef

void

tcp_drain()

{

	/* XXX */

}

/*

 * When a source quench is received, close congestion window

 * to one segment.  We will gradually open it again as we proceed.

 */

void

tcp_quench(i, errno)

	int errno;

{

	struct tcpcb *tp = intotcpcb(inp);

	if (tp)

		tp->snd_cwnd = tp->t_maxseg;

}

#endif /* notdef */

/*

 * TCP protocol interface to socket abstraction.

 */

/*

 * 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.

 */

void

tcp_sockclosed(tp)

	struct tcpcb *tp;

{

	DEBUG_CALL("tcp_sockclosed");

	DEBUG_ARG("tp = %lx", (long)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;

	}

/*	soisfdisconnecting(tp->t_socket); */

	if (tp && tp->t_state >= TCPS_FIN_WAIT_2)

		soisfdisconnected(tp->t_socket);

	if (tp)

		tcp_output(tp);

}

/*

 * Connect to a host on the Internet

 * Called by tcp_input

 * Only do a connect, the tcp fields will be set in tcp_input

 * return 0 if there's a result of the connect,

 * else return -1 means we're still connecting

 * The return value is almost always -1 since the socket is

 * nonblocking.  Connect returns after the SYN is sent, and does

 * not wait for ACK+SYN.

 */

int tcp_fconnect(so)

     struct socket *so;

{

  int ret=0;

  DEBUG_CALL("tcp_fconnect");

  DEBUG_ARG("so = %lx", (long )so);

  if( (ret=so->s=socket(AF_INET,SOCK_STREAM,0)) >= 0) {

    int opt, s=so->s;

    struct sockaddr_in addr;

    fd_nonblock(s);

    opt = 1;

    setsockopt(s,SOL_SOCKET,SO_REUSEADDR,(char *)&opt,sizeof(opt ));

    opt = 1;

    setsockopt(s,SOL_SOCKET,SO_OOBINLINE,(char *)&opt,sizeof(opt ));

    addr.sin_family = AF_INET;

    if ((so->so_faddr.s_addr & htonl(0xffffff00)) == special_addr.s_addr) {

      /* It's an alias */

      switch(ntohl(so->so_faddr.s_addr) & 0xff) {

      case CTL_DNS:

	addr.sin_addr = dns_addr;

	break;

      case CTL_ALIAS:

      default:

	addr.sin_addr = loopback_addr;

	break;

      }

    } else

      addr.sin_addr = so->so_faddr;

    addr.sin_port = so->so_fport;

    DEBUG_MISC((dfd, " connect()ing, addr.sin_port=%d, "

		"addr.sin_addr.s_addr=%.16s\n",

		ntohs(addr.sin_port), inet_ntoa(addr.sin_addr)));

    /* We don't care what port we get */

    ret = connect(s,(struct sockaddr *)&addr,sizeof (addr));

    /*

     * If it's not in progress, it failed, so we just return 0,

     * without clearing SS_NOFDREF

     */

    soisfconnecting(so);

  }

  return(ret);

}

/*

 * Accept the socket and connect to the local-host

 *

 * We have a problem. The correct thing to do would be

 * to first connect to the local-host, and only if the

 * connection is accepted, then do an accept() here.

 * But, a) we need to know who's trying to connect

 * to the socket to be able to SYN the local-host, and

 * b) we are already connected to the foreign host by

 * the time it gets to accept(), so... We simply accept

 * here and SYN the local-host.

 */

void

tcp_connect(inso)

	struct socket *inso;

{

	struct socket *so;

	struct sockaddr_in addr;

	socklen_t addrlen = sizeof(struct sockaddr_in);

	struct tcpcb *tp;

	int s, opt;

	DEBUG_CALL("tcp_connect");

	DEBUG_ARG("inso = %lx", (long)inso);

	/*

	 * If it's an SS_ACCEPTONCE socket, no need to socreate()

	 * another socket, just use the accept() socket.

	 */

	if (inso->so_state & SS_FACCEPTONCE) {

		/* FACCEPTONCE already have a tcpcb */

		so = inso;

	} else {

		if ((so = socreate()) == NULL) {

			/* If it failed, get rid of the pending connection */

			closesocket(accept(inso->s,(struct sockaddr *)&addr,&addrlen));

			return;

		}

		if (tcp_attach(so) < 0) {

			free(so); /* NOT sofree */

			return;

		}

		so->so_laddr = inso->so_laddr;

		so->so_lport = inso->so_lport;

	}

	(void) tcp_mss(sototcpcb(so), 0);

	if ((s = accept(inso->s,(struct sockaddr *)&addr,&addrlen)) < 0) {

		tcp_close(sototcpcb(so)); /* This will sofree() as well */

		return;

	}

	fd_nonblock(s);

	opt = 1;

	setsockopt(s,SOL_SOCKET,SO_REUSEADDR,(char *)&opt,sizeof(int));

	opt = 1;

	setsockopt(s,SOL_SOCKET,SO_OOBINLINE,(char *)&opt,sizeof(int));

	opt = 1;

	setsockopt(s,IPPROTO_TCP,TCP_NODELAY,(char *)&opt,sizeof(int));

	so->so_fport = addr.sin_port;

	so->so_faddr = addr.sin_addr;

	/* Translate connections from localhost to the real hostname */

	if (so->so_faddr.s_addr == 0 || so->so_faddr.s_addr == loopback_addr.s_addr)

	   so->so_faddr = alias_addr;

	/* Close the accept() socket, set right state */

	if (inso->so_state & SS_FACCEPTONCE) {

		closesocket(so->s); /* If we only accept once, close the accept() socket */

		so->so_state = SS_NOFDREF; /* Don't select it yet, even though we have an FD */

					   /* if it's not FACCEPTONCE, it's already NOFDREF */

	}

	so->s = s;

	so->so_iptos = tcp_tos(so);

	tp = sototcpcb(so);

	tcp_template(tp);

	/* 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); */ /* NOFDREF used instead */

	STAT(tcpstat.tcps_connattempt++);

	tp->t_state = TCPS_SYN_SENT;

	tp->t_timer[TCPT_KEEP] = TCPTV_KEEP_INIT;

	tp->iss = tcp_iss;

	tcp_iss += TCP_ISSINCR/2;

	tcp_sendseqinit(tp);

	tcp_output(tp);

}

/*

 * Attach a TCPCB to a socket.