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Annotation of previous_trunk/src/slirp/ip_output.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1982, 1986, 1988, 1990, 1993
        !             3:  *     The Regents of the University of California.  All rights reserved.
        !             4:  *
        !             5:  * Redistribution and use in source and binary forms, with or without
        !             6:  * modification, are permitted provided that the following conditions
        !             7:  * are met:
        !             8:  * 1. Redistributions of source code must retain the above copyright
        !             9:  *    notice, this list of conditions and the following disclaimer.
        !            10:  * 2. Redistributions in binary form must reproduce the above copyright
        !            11:  *    notice, this list of conditions and the following disclaimer in the
        !            12:  *    documentation and/or other materials provided with the distribution.
        !            13:  * 3. Neither the name of the University nor the names of its contributors
        !            14:  *    may be used to endorse or promote products derived from this software
        !            15:  *    without specific prior written permission.
        !            16:  *
        !            17:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
        !            18:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
        !            19:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
        !            20:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
        !            21:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
        !            22:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
        !            23:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
        !            24:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
        !            25:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
        !            26:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
        !            27:  * SUCH DAMAGE.
        !            28:  *
        !            29:  *     @(#)ip_output.c 8.3 (Berkeley) 1/21/94
        !            30:  * ip_output.c,v 1.9 1994/11/16 10:17:10 jkh Exp
        !            31:  */
        !            32: 
        !            33: /*
        !            34:  * Changes and additions relating to SLiRP are
        !            35:  * Copyright (c) 1995 Danny Gasparovski.
        !            36:  *
        !            37:  * Please read the file COPYRIGHT for the
        !            38:  * terms and conditions of the copyright.
        !            39:  */
        !            40: 
        !            41: #include <slirp.h>
        !            42: 
        !            43: u_int16_t ip_id;
        !            44: 
        !            45: /*
        !            46:  * IP output.  The packet in mbuf chain m contains a skeletal IP
        !            47:  * header (with len, off, ttl, proto, tos, src, dst).
        !            48:  * The mbuf chain containing the packet will be freed.
        !            49:  * The mbuf opt, if present, will not be freed.
        !            50:  */
        !            51: int
        !            52: ip_output(so, m0)
        !            53:        struct socket *so;
        !            54:        struct mbuf *m0;
        !            55: {
        !            56:        register struct ip *ip;
        !            57:        register struct mbuf *m = m0;
        !            58:        register u_int hlen = sizeof(struct ip);
        !            59:        u_int len, off;
        !            60:        int error = 0;
        !            61: 
        !            62:        DEBUG_CALL("ip_output");
        !            63:        DEBUG_ARG("so = %lx", (long)so);
        !            64:        DEBUG_ARG("m0 = %lx", (long)m0);
        !            65:        
        !            66:        /* We do no options */
        !            67: /*     if (opt) {
        !            68:  *             m = ip_insertoptions(m, opt, &len);
        !            69:  *             hlen = len;
        !            70:  *     }
        !            71:  */
        !            72:        ip = mtod(m, struct ip *);
        !            73:        /*
        !            74:         * Fill in IP header.
        !            75:         */
        !            76:        ip->ip_v = IPVERSION;
        !            77:        ip->ip_off &= IP_DF;
        !            78:        ip->ip_id = htons(ip_id++);
        !            79:        ip->ip_hl = hlen >> 2;
        !            80:        ipstat.ips_localout++;
        !            81: 
        !            82:        /*
        !            83:         * Verify that we have any chance at all of being able to queue
        !            84:         *      the packet or packet fragments
        !            85:         */
        !            86:        /* XXX Hmmm... */
        !            87: /*     if (if_queued > if_thresh && towrite <= 0) {
        !            88:  *             error = ENOBUFS;
        !            89:  *             goto bad;
        !            90:  *     }
        !            91:  */
        !            92:        
        !            93:        /*
        !            94:         * If small enough for interface, can just send directly.
        !            95:         */
        !            96:        if ((u_int16_t)ip->ip_len <= if_mtu) {
        !            97:                ip->ip_len = htons((u_int16_t)ip->ip_len);
        !            98:                ip->ip_off = htons((u_int16_t)ip->ip_off);
        !            99:                ip->ip_sum = 0;
        !           100:                ip->ip_sum = cksum(m, hlen);
        !           101: 
        !           102:                if_output(so, m);
        !           103:                goto done;
        !           104:        }
        !           105: 
        !           106:        /*
        !           107:         * Too large for interface; fragment if possible.
        !           108:         * Must be able to put at least 8 bytes per fragment.
        !           109:         */
        !           110:        if (ip->ip_off & IP_DF) {
        !           111:                error = -1;
        !           112:                ipstat.ips_cantfrag++;
        !           113:                goto bad;
        !           114:        }
        !           115:        
        !           116:        len = (if_mtu - hlen) &~ 7;       /* ip databytes per packet */
        !           117:        if (len < 8) {
        !           118:                error = -1;
        !           119:                goto bad;
        !           120:        }
        !           121: 
        !           122:     {
        !           123:        int mhlen, firstlen = len;
        !           124:        struct mbuf **mnext = &m->m_nextpkt;
        !           125: 
        !           126:        /*
        !           127:         * Loop through length of segment after first fragment,
        !           128:         * make new header and copy data of each part and link onto chain.
        !           129:         */
        !           130:        m0 = m;
        !           131:        mhlen = sizeof (struct ip);
        !           132:        for (off = hlen + len; off < ip->ip_len; off += len) {
        !           133:          register struct ip *mhip;
        !           134:          m = m_get();
        !           135:          if (m == 0) {
        !           136:            error = -1;
        !           137:            ipstat.ips_odropped++;
        !           138:            goto sendorfree;
        !           139:          }
        !           140:          m->m_data += if_maxlinkhdr;
        !           141:          mhip = mtod(m, struct ip *);
        !           142:          *mhip = *ip;
        !           143:                
        !           144:                /* No options */
        !           145: /*             if (hlen > sizeof (struct ip)) {
        !           146:  *                     mhlen = ip_optcopy(ip, mhip) + sizeof (struct ip);
        !           147:  *                     mhip->ip_hl = mhlen >> 2;
        !           148:  *             }
        !           149:  */
        !           150:          m->m_len = mhlen;
        !           151:          mhip->ip_off = ((off - hlen) >> 3) + (ip->ip_off & ~IP_MF);
        !           152:          if (ip->ip_off & IP_MF)
        !           153:            mhip->ip_off |= IP_MF;
        !           154:          if (off + len >= (u_int16_t)ip->ip_len)
        !           155:            len = (u_int16_t)ip->ip_len - off;
        !           156:          else 
        !           157:            mhip->ip_off |= IP_MF;
        !           158:          mhip->ip_len = htons((u_int16_t)(len + mhlen));
        !           159:          
        !           160:          if (m_copy(m, m0, off, len) < 0) {
        !           161:            error = -1;
        !           162:            goto sendorfree;
        !           163:          }
        !           164:          
        !           165:          mhip->ip_off = htons((u_int16_t)mhip->ip_off);
        !           166:          mhip->ip_sum = 0;
        !           167:          mhip->ip_sum = cksum(m, mhlen);
        !           168:          *mnext = m;
        !           169:          mnext = &m->m_nextpkt;
        !           170:          ipstat.ips_ofragments++;
        !           171:        }
        !           172:        /*
        !           173:         * Update first fragment by trimming what's been copied out
        !           174:         * and updating header, then send each fragment (in order).
        !           175:         */
        !           176:        m = m0;
        !           177:        m_adj(m, hlen + firstlen - ip->ip_len);
        !           178:        ip->ip_len = htons((u_int16_t)m->m_len);
        !           179:        ip->ip_off = htons((u_int16_t)(ip->ip_off | IP_MF));
        !           180:        ip->ip_sum = 0;
        !           181:        ip->ip_sum = cksum(m, hlen);
        !           182: sendorfree:
        !           183:        for (m = m0; m; m = m0) {
        !           184:                m0 = m->m_nextpkt;
        !           185:                m->m_nextpkt = 0;
        !           186:                if (error == 0)
        !           187:                        if_output(so, m);
        !           188:                else
        !           189:                        m_freem(m);
        !           190:        }
        !           191: 
        !           192:        if (error == 0)
        !           193:                ipstat.ips_fragmented++;
        !           194:     }
        !           195: 
        !           196: done:
        !           197:        return (error);
        !           198: 
        !           199: bad:
        !           200:        m_freem(m0);
        !           201:        goto done;
        !           202: }

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