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/*
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 * Copyright (c) 1982, 1986, 1988, 1990, 1993
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 *        The Regents of the University of California.  All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 * 1. Redistributions of source code must retain the above copyright
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 *    notice, this list of conditions and the following disclaimer.
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 * 2. Redistributions in binary form must reproduce the above copyright
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 *    notice, this list of conditions and the following disclaimer in the
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 *    documentation and/or other materials provided with the distribution.
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 * 3. All advertising materials mentioning features or use of this software
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 *    must display the following acknowledgement:
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 *        This product includes software developed by the University of
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 *        California, Berkeley and its contributors.
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 * 4. Neither the name of the University nor the names of its contributors
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 *    may be used to endorse or promote products derived from this software
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 *    without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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 * SUCH DAMAGE.
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 *
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 *        @(#)ip_output.c        8.3 (Berkeley) 1/21/94
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 * ip_output.c,v 1.9 1994/11/16 10:17:10 jkh Exp
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 */
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/*
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 * Changes and additions relating to SLiRP are
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 * Copyright (c) 1995 Danny Gasparovski.
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 *
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 * Please read the file COPYRIGHT for the
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 * terms and conditions of the copyright.
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 */
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#include <slirp.h>
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u_int16_t ip_id;
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/*
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 * IP output.  The packet in mbuf chain m contains a skeletal IP
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 * header (with len, off, ttl, proto, tos, src, dst).
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 * The mbuf chain containing the packet will be freed.
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 * The mbuf opt, if present, will not be freed.
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 */
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int
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ip_output(so, m0)
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        struct socket *so;
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        struct mbuf *m0;
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{
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        register struct ip *ip;
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        register struct mbuf *m = m0;
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        register int hlen = sizeof(struct ip );
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        int len, off, error = 0;
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        DEBUG_CALL("ip_output");
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        DEBUG_ARG("so = %lx", (long)so);
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        DEBUG_ARG("m0 = %lx", (long)m0);
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        /* We do no options */
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/*        if (opt) {
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 *                m = ip_insertoptions(m, opt, &len);
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 *                hlen = len;
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 *        }
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 */
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        ip = mtod(m, struct ip *);
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        /*
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         * Fill in IP header.
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         */
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        ip->ip_v = IPVERSION;
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        ip->ip_off &= IP_DF;
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        ip->ip_id = htons(ip_id++);
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        ip->ip_hl = hlen >> 2;
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        ipstat.ips_localout++;
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        /*
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         * Verify that we have any chance at all of being able to queue
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         *      the packet or packet fragments
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         */
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        /* XXX Hmmm... */
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/*        if (if_queued > if_thresh && towrite <= 0) {
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 *                error = ENOBUFS;
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 *                goto bad;
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 *        }
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 */
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        /*
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         * If small enough for interface, can just send directly.
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         */
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        if ((u_int16_t)ip->ip_len <= if_mtu) {
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                ip->ip_len = htons((u_int16_t)ip->ip_len);
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                ip->ip_off = htons((u_int16_t)ip->ip_off);
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                ip->ip_sum = 0;
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                ip->ip_sum = cksum(m, hlen);
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                if_output(so, m);
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                goto done;
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        }
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        /*
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         * Too large for interface; fragment if possible.
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         * Must be able to put at least 8 bytes per fragment.
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         */
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        if (ip->ip_off & IP_DF) {
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                error = -1;
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                ipstat.ips_cantfrag++;
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                goto bad;
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        }
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        len = (if_mtu - hlen) &~ 7;       /* ip databytes per packet */
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        if (len < 8) {
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                error = -1;
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                goto bad;
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        }
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    {
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        int mhlen, firstlen = len;
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        struct mbuf **mnext = &m->m_nextpkt;
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        /*
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         * Loop through length of segment after first fragment,
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         * make new header and copy data of each part and link onto chain.
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         */
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        m0 = m;
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        mhlen = sizeof (struct ip);
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        for (off = hlen + len; off < (u_int16_t)ip->ip_len; off += len) {
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          register struct ip *mhip;
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          m = m_get();
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          if (m == 0) {
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            error = -1;
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            ipstat.ips_odropped++;
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            goto sendorfree;
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          }
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          m->m_data += if_maxlinkhdr;
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          mhip = mtod(m, struct ip *);
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          *mhip = *ip;
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                /* No options */
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/*                if (hlen > sizeof (struct ip)) {
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 *                        mhlen = ip_optcopy(ip, mhip) + sizeof (struct ip);
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 *                        mhip->ip_hl = mhlen >> 2;
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 *                }
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 */
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          m->m_len = mhlen;
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          mhip->ip_off = ((off - hlen) >> 3) + (ip->ip_off & ~IP_MF);
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          if (ip->ip_off & IP_MF)
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            mhip->ip_off |= IP_MF;
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          if (off + len >= (u_int16_t)ip->ip_len)
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            len = (u_int16_t)ip->ip_len - off;
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          else
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            mhip->ip_off |= IP_MF;
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          mhip->ip_len = htons((u_int16_t)(len + mhlen));
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          if (m_copy(m, m0, off, len) < 0) {
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            error = -1;
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            goto sendorfree;
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          }
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          mhip->ip_off = htons((u_int16_t)mhip->ip_off);
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          mhip->ip_sum = 0;
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          mhip->ip_sum = cksum(m, mhlen);
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          *mnext = m;
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          mnext = &m->m_nextpkt;
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          ipstat.ips_ofragments++;
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        }
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        /*
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         * Update first fragment by trimming what's been copied out
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         * and updating header, then send each fragment (in order).
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         */
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        m = m0;
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        m_adj(m, hlen + firstlen - (u_int16_t)ip->ip_len);
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        ip->ip_len = htons((u_int16_t)m->m_len);
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        ip->ip_off = htons((u_int16_t)(ip->ip_off | IP_MF));
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        ip->ip_sum = 0;
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        ip->ip_sum = cksum(m, hlen);
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sendorfree:
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        for (m = m0; m; m = m0) {
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                m0 = m->m_nextpkt;
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                m->m_nextpkt = 0;
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                if (error == 0)
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                        if_output(so, m);
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                else
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                        m_freem(m);
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        }
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        if (error == 0)
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                ipstat.ips_fragmented++;
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    }
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done:
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        return (error);
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bad:
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        m_freem(m0);
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        goto done;
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}