/*

 * 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.

 *

 *	@(#)ip_output.c	8.3 (Berkeley) 1/21/94

 * ip_output.c,v 1.9 1994/11/16 10:17:10 jkh Exp

 */

/*

 * Changes and additions relating to SLiRP are

 * Copyright (c) 1995 Danny Gasparovski.

 *

 * Please read the file COPYRIGHT for the

 * terms and conditions of the copyright.

 */

#include <slirp.h>

u_int16_t ip_id;

/* Number of packets queued before we start sending

 * (to prevent allocing too many mbufs) */

#define IF_THRESH 10

/*

 * IP output.  The packet in mbuf chain m contains a skeletal IP

 * header (with len, off, ttl, proto, tos, src, dst).

 * The mbuf chain containing the packet will be freed.

 * The mbuf opt, if present, will not be freed.

 */

int

ip_output(so, m0)

	struct socket *so;

	struct mbuf *m0;

{

	register struct ip *ip;

	register struct mbuf *m = m0;

	register int hlen = sizeof(struct ip );

	int len, off, error = 0;

	DEBUG_CALL("ip_output");

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

	DEBUG_ARG("m0 = %lx", (long)m0);

	/* We do no options */

/*	if (opt) {

 *		m = ip_insertoptions(m, opt, &len);

 *		hlen = len;

 *	}

 */

	ip = mtod(m, struct ip *);

	/*

	 * Fill in IP header.

	 */

	ip->ip_v = IPVERSION;

	ip->ip_off &= IP_DF;

	ip->ip_id = htons(ip_id++);

	ip->ip_hl = hlen >> 2;

	STAT(ipstat.ips_localout++);

	/*

	 * Verify that we have any chance at all of being able to queue

	 *      the packet or packet fragments

	 */

	/* XXX Hmmm... */

/*	if (if_queued > IF_THRESH && towrite <= 0) {

 *		error = ENOBUFS;

 *		goto bad;

 *	}

 */

	/*

	 * If small enough for interface, can just send directly.

	 */

	if ((u_int16_t)ip->ip_len <= IF_MTU) {

		ip->ip_len = htons((u_int16_t)ip->ip_len);

		ip->ip_off = htons((u_int16_t)ip->ip_off);

		ip->ip_sum = 0;

		ip->ip_sum = cksum(m, hlen);

		if_output(so, m);

		goto done;

	}

	/*

	 * Too large for interface; fragment if possible.

	 * Must be able to put at least 8 bytes per fragment.

	 */

	if (ip->ip_off & IP_DF) {

		error = -1;

		STAT(ipstat.ips_cantfrag++);

		goto bad;

	}

	len = (IF_MTU - hlen) &~ 7;       /* ip databytes per packet */

	if (len < 8) {

		error = -1;

		goto bad;

	}

    {

	int mhlen, firstlen = len;

	struct mbuf **mnext = &m->m_nextpkt;

	/*

	 * Loop through length of segment after first fragment,

	 * make new header and copy data of each part and link onto chain.

	 */

	m0 = m;

	mhlen = sizeof (struct ip);

	for (off = hlen + len; off < (u_int16_t)ip->ip_len; off += len) {

	  register struct ip *mhip;

	  m = m_get();

	  if (m == 0) {

	    error = -1;

	    STAT(ipstat.ips_odropped++);

	    goto sendorfree;

	  }

	  m->m_data += IF_MAXLINKHDR;

	  mhip = mtod(m, struct ip *);

	  *mhip = *ip;

		/* No options */

/*		if (hlen > sizeof (struct ip)) {

 *			mhlen = ip_optcopy(ip, mhip) + sizeof (struct ip);

 *			mhip->ip_hl = mhlen >> 2;

 *		}

 */

	  m->m_len = mhlen;

	  mhip->ip_off = ((off - hlen) >> 3) + (ip->ip_off & ~IP_MF);

	  if (ip->ip_off & IP_MF)

	    mhip->ip_off |= IP_MF;

	  if (off + len >= (u_int16_t)ip->ip_len)

	    len = (u_int16_t)ip->ip_len - off;

	  else

	    mhip->ip_off |= IP_MF;

	  mhip->ip_len = htons((u_int16_t)(len + mhlen));

	  if (m_copy(m, m0, off, len) < 0) {

	    error = -1;

	    goto sendorfree;

	  }

	  mhip->ip_off = htons((u_int16_t)mhip->ip_off);

	  mhip->ip_sum = 0;

	  mhip->ip_sum = cksum(m, mhlen);

	  *mnext = m;

	  mnext = &m->m_nextpkt;

	  STAT(ipstat.ips_ofragments++);

	}

	/*

	 * Update first fragment by trimming what's been copied out

	 * and updating header, then send each fragment (in order).

	 */

	m = m0;

	m_adj(m, hlen + firstlen - (u_int16_t)ip->ip_len);

	ip->ip_len = htons((u_int16_t)m->m_len);

	ip->ip_off = htons((u_int16_t)(ip->ip_off | IP_MF));

	ip->ip_sum = 0;

	ip->ip_sum = cksum(m, hlen);

sendorfree:

	for (m = m0; m; m = m0) {

		m0 = m->m_nextpkt;

		m->m_nextpkt = 0;

		if (error == 0)

			if_output(so, m);

		else

			m_freem(m);

	}

	if (error == 0)

		STAT(ipstat.ips_fragmented++);

    }

done:

	return (error);

bad:

	m_freem(m0);

	goto done;

}