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/*
* $Id: libnet_build_udp.c,v 1.11 2004/04/13 17:32:28 mike Exp $
*
* libnet
* libnet_build_udp.c - UDP packet assembler
*
* Copyright (c) 1998 - 2004 Mike D. Schiffman <mike@infonexus.com>
* 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.
*
*/
#include "common.h"
libnet_ptag_t
libnet_build_udp(uint16_t sp, uint16_t dp, uint16_t len, uint16_t sum,
const uint8_t *payload, uint32_t payload_s, libnet_t *l, libnet_ptag_t ptag)
{
uint32_t n;
libnet_pblock_t *p;
struct libnet_udp_hdr udp_hdr;
if (l == NULL)
{
return (-1);
}
n = LIBNET_UDP_H + payload_s; /* size of memory block */
/*
* Find the existing protocol block if a ptag is specified, or create
* a new one.
*/
p = libnet_pblock_probe(l, ptag, n, LIBNET_PBLOCK_UDP_H);
if (p == NULL)
{
return (-1);
}
memset(&udp_hdr, 0, sizeof(udp_hdr));
udp_hdr.uh_sport = htons(sp); /* source port */
udp_hdr.uh_dport = htons(dp); /* destination port */
udp_hdr.uh_ulen = htons(len); /* total length of UDP packet*/
udp_hdr.uh_sum = (sum ? htons(sum) : 0);/* checksum */
n = libnet_pblock_append(l, p, (uint8_t *)&udp_hdr, LIBNET_UDP_H);
if (n == -1)
{
goto bad;
}
/* boilerplate payload sanity check / append macro */
LIBNET_DO_PAYLOAD(l, p);
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 ? ptag : libnet_pblock_update(l, p, len, LIBNET_PBLOCK_UDP_H));
bad:
libnet_pblock_delete(l, p);
return (-1);
}
/* EOF */
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