libnet_build_mpls.c

tcp数据流重放工具

/*
 *  $Id: libnet_build_mpls.c,v 1.6 2003/09/23 22:36:55 mike Exp $
 *
 *  libnet
 *  libnet_build_mpls.c - MPLS packet assembler
 *
 *  Copyright (c) 1998 - 2003 Mike D. Schiffman <[e-mail]>
 *  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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 *
 */

#if (HAVE_CONFIG_H)
#include "../include/config.h"
#endif
#if (!(_WIN32) || (__CYGWIN__)) 
#include "../include/libnet.h"
#else
#include "../include/win32/libnet.h"
#endif

libnet_ptag_t
libnet_build_mpls(u_int32_t label, u_int8_t experimental, u_int8_t bos, u_int8_t ttl,
            u_int8_t *payload, u_int32_t payload_s, libnet_t *l, libnet_ptag_t ptag)
{
    u_int32_t n, h;
    libnet_pblock_t *p;
    struct libnet_mpls_hdr mpls_hdr;

    if (l == NULL)
    { 
        return (-1);
    } 

    n = LIBNET_MPLS_H + payload_s;
    h = 0;

    /*
     *  Find the existing protocol block if a ptag is specified, or create
     *  a new one.
     */
    p = libnet_pblock_probe(l, ptag, n, LIBNET_PBLOCK_MPLS_H);
    if (p == NULL)
    {
        return (-1);
    }

	memset(&mpls_hdr, 0, sizeof(mpls_hdr));
	mpls_hdr.mpls_les = htonl((((label & 0x000fffff) << 12) |
                              ((experimental & 0x07) <<  9) |
                              ((bos & 0x01)          <<  8) |
                              ((ttl & 0xff))));

    n = libnet_pblock_append(l, p, (u_int8_t *)&mpls_hdr, LIBNET_MPLS_H);
    if (n == -1)
    {
        goto bad;
    }

    if ((payload && !payload_s) || (!payload && payload_s))
    {
         snprintf(l->err_buf, LIBNET_ERRBUF_SIZE,
			     "%s(): payload inconsistency\n", __func__);
        goto bad;
    }

    if (payload && payload_s)
    {
        n = libnet_pblock_append(l, p, payload, payload_s);
        if (n == -1)
        {
            goto bad;
        }
    }

    /*
     *  The link offset is actually 4 bytes further into the header than
     *  before (the MPLS header adds this 4 bytes).  We need to update the
     *  link offset pointer. XXX - should we set this here?
     *  Probably not.  We should make pblock_coalesce check the pblock type
     *  and adjust accordingly.
     */
    l->link_offset += 4;

    return (ptag ? ptag : libnet_pblock_update(l, p, h, LIBNET_PBLOCK_MPLS_H));
bad:
    libnet_pblock_delete(l, p);
    return (-1);
}

/* EOF */