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/*

 * 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;

}