libnet_build_ip.c

tcp数据流重放工具

/*
 *  $Id: libnet_build_ip.c,v 1.10 2003/09/23 22:36:55 mike Exp $
 *
 *  libnet
 *  libnet_build_ip.c - IP 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_ipv4(u_int16_t len, u_int8_t tos, u_int16_t id, u_int16_t frag,
            u_int8_t ttl, u_int8_t prot, u_int16_t sum, u_int32_t src, u_int32_t dst,
            u_int8_t *payload, u_int32_t payload_s, libnet_t *l, libnet_ptag_t ptag)
{
    int offset;
    u_int32_t h, n, i, j;
    libnet_pblock_t *p, *p_data, *p_temp;
    struct libnet_ipv4_hdr ip_hdr;
    libnet_ptag_t ptag_data, ptag_hold;

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

    n = LIBNET_IPV4_H + payload_s;          /* size of memory block */
    h = len;                                /* header length */
    ptag_data = 0;                          /* used if options are present */

    if (h + payload_s > IP_MAXPACKET)
    {
         snprintf(l->err_buf, LIBNET_ERRBUF_SIZE,
			     "%s(): IP packet too large\n", __func__);
        return (-1);
    }

    /*
     *  Find the existing protocol block if a ptag is specified, or create
     *  a new one.
     */
    p = libnet_pblock_probe(l, ptag, n, LIBNET_PBLOCK_IPV4_H);
    if (p == NULL)
    {
        return (-1);
    }

	memset(&ip_hdr, 0, sizeof(ip_hdr));
    ip_hdr.ip_v          = 4;                         /* version 4 */
    ip_hdr.ip_hl         = 5;                         /* 20 byte header */

    /* check to see if there are IP options to include */
    if (p->prev)
    {
        if (p->prev->type == LIBNET_PBLOCK_IPO_H)
        {
            /*
             *  Count up number of 32-bit words in options list, padding if
             *  neccessary.
             */
            for (i = 0, j = 0; i < p->prev->b_len; i++)
            {
                (i % 4) ? j : j++;
            }
            ip_hdr.ip_hl += j;
        }
    }

    ip_hdr.ip_tos        = tos;                       /* IP tos */
    ip_hdr.ip_len        = htons(h);                  /* total length */
    ip_hdr.ip_id         = htons(id);                 /* IP ID */
    ip_hdr.ip_off        = htons(frag);               /* fragmentation flags */
    ip_hdr.ip_ttl        = ttl;                       /* time to live */
    ip_hdr.ip_p          = prot;                      /* transport protocol */
    ip_hdr.ip_sum        = sum;                       /* checksum */
    ip_hdr.ip_src.s_addr = src;                       /* source ip */
    ip_hdr.ip_dst.s_addr = dst;                       /* destination ip */
    
	n = libnet_pblock_append(l, p, (u_int8_t *)&ip_hdr, LIBNET_IPV4_H);
    if (n == -1)
    {
        goto bad;
    }

    /* save the original ptag value */
    ptag_hold = ptag;

    if (ptag == LIBNET_PTAG_INITIALIZER)
    {
        ptag = libnet_pblock_update(l, p, LIBNET_IPV4_H, LIBNET_PBLOCK_IPV4_H);
    }

    /* find and set the appropriate ptag, or else use the default of 0 */
    offset = payload_s;
    if (ptag_hold && p->prev)
    {
        p_temp = p->prev;
        while (p_temp->prev &&
              (p_temp->type != LIBNET_PBLOCK_IPDATA) &&
              (p_temp->type != LIBNET_PBLOCK_IPV4_H))
        {
            p_temp = p_temp->prev;
        }

        if (p_temp->type == LIBNET_PBLOCK_IPDATA)
        {
            ptag_data = p_temp->ptag;
            offset -=  p_temp->b_len;
            p->h_len += offset;
        }
        else
        {
             snprintf(l->err_buf, LIBNET_ERRBUF_SIZE,
                     "%s(): IPv4 data pblock not found\n", __func__);
        }
    }

    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)
    {
        /* update ptag_data with the new payload */
        p_data = libnet_pblock_probe(l, ptag_data, payload_s,
                LIBNET_PBLOCK_IPDATA);
        if (p_data == NULL)
        {
            return (-1);
        }

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

        if (ptag_data == LIBNET_PTAG_INITIALIZER)
        {
            if (p_data->prev->type == LIBNET_PBLOCK_IPV4_H)
            {
                libnet_pblock_update(l, p_data, payload_s,
                        LIBNET_PBLOCK_IPDATA);
                /* swap pblocks to correct the protocol order */
                libnet_pblock_swap(l, p->ptag, p_data->ptag); 
            }
            else
            {
                /* update without setting this as the final pblock */
                p_data->type  =  LIBNET_PBLOCK_IPDATA;
                p_data->ptag  =  ++(l->ptag_state);
                p_data->h_len =  payload_s;

                /* Adjust h_len for checksum. */
                p->h_len += payload_s;

                /* data was added after the initial construction */
                for (p_temp = l->protocol_blocks;
                        p_temp->type == LIBNET_PBLOCK_IPV4_H ||
                        p_temp->type == LIBNET_PBLOCK_IPO_H;
                        p_temp = p_temp->next)
                {
                    libnet_pblock_insert_before(l, p_temp->ptag, p_data->ptag);
                    break;
                }

                /* the end block needs to have its next pointer cleared */
                l->pblock_end->next = NULL;
            }

            if (p_data->prev && p_data->prev->type == LIBNET_PBLOCK_IPO_H)
            {
                libnet_pblock_swap(l, p_data->prev->ptag, p_data->ptag); 
            }
        }
    }
    else
    {
        p_data = libnet_pblock_find(l, ptag_data);
        if (p_data) 
        {
            libnet_pblock_delete(l, p_data);
        }
        else
        {
            /* 
             * XXX - When this completes successfully, libnet errbuf contains 
             * an error message so to come correct, we'll clear it.
             */ 
            memset(l->err_buf, 0, sizeof (l->err_buf));
        }
    }
    if (sum == 0)
    {
        /*
         *  If checksum is zero, by default libnet will compute a checksum
         *  for the user.  The programmer can override this by calling
         *  libnet_toggle_checksum(l, ptag, 1);
         */
        libnet_pblock_setflags(p, LIBNET_PBLOCK_DO_CHECKSUM);
    }
    return (ptag);
bad:
    libnet_pblock_delete(l, p);
    return (-1);
}

libnet_ptag_t
libnet_autobuild_ipv4(u_int16_t len, u_int8_t prot, u_int32_t dst, libnet_t *l)
{
    u_int32_t n, i, j, src;
    u_int16_t h;
    libnet_pblock_t *p;
    libnet_ptag_t ptag;
    struct libnet_ipv4_hdr ip_hdr;

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

    n = LIBNET_IPV4_H;                                /* size of memory block */
    h = len;                                          /* header length */
    ptag = LIBNET_PTAG_INITIALIZER;
    src = libnet_get_ipaddr4(l);
    if (src == -1)
    {
        /* err msg set in libnet_get_ipaddr() */ 
        return (-1);
    }

    /*
     *  Create a new pblock.
     */
    p = libnet_pblock_probe(l, ptag, n, LIBNET_PBLOCK_IPV4_H);
    if (p == NULL)