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/*
* Copyright (c) 2007
* Shrew Soft Inc. 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.
* 3. Redistributions in any form must be accompanied by information on
* how to obtain complete source code for the software and any
* accompanying software that uses the software. The source code
* must either be included in the distribution or be available for no
* more than the cost of distribution plus a nominal fee, and must be
* freely redistributable under reasonable conditions. For an
* executable file, complete source code means the source code for all
* modules it contains. It does not include source code for modules or
* files that typically accompany the major components of the operating
* system on which the executable file runs.
*
* THIS SOFTWARE IS PROVIDED BY SHREW SOFT INC ``AS IS'' AND ANY EXPRESS
* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR
* NON-INFRINGEMENT, ARE DISCLAIMED. IN NO EVENT SHALL SHREW SOFT INC
* 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.
*
* AUTHOR : Matthew Grooms
* mgrooms@shrew.net
*
*/
#include "libip.h"
uint16_t _PACKET_IP::checksum()
{
uint16_t * data = ( uint16_t * ) data_buff;
uint16_t size = sizeof( IP_HEADER );
uint32_t cksum = 0;
while( size > 1 )
{
cksum += *data++;
size -= sizeof( uint16_t );
}
if( size )
cksum += *( uint8_t * ) data;
while( cksum >> 16 )
cksum = ( cksum & 0xffff ) + ( cksum >> 16 );
return ( ( uint16_t ) ~cksum );
}
bool _PACKET_IP::read( in_addr & addr_src, in_addr & addr_dst, unsigned char & prot )
{
IP_HEADER ip_header;
data_oset = 0;
if( !get( &ip_header, sizeof( IP_HEADER ) ) )
return false;
unsigned short ip_hdsize = 4 * ( ip_header.verlen & 0xF );
addr_src.s_addr = ip_header.ip_src;
addr_dst.s_addr = ip_header.ip_dst;
prot = ip_header.protocol;
if( ip_hdsize > data_oset )
get_null( ip_hdsize - data_oset );
return true;
}
bool _PACKET_IP::write( in_addr addr_src, in_addr addr_dst, unsigned short ident, unsigned char prot )
{
del();
IP_HEADER ip_header;
ip_header.verlen = IP_V4_VERLEN;
ip_header.tos = 0;
ip_header.size = 0;
ip_header.ident = ident;
ip_header.flags = 0;
ip_header.ttl = 64;
ip_header.protocol = prot;
ip_header.ip_src = addr_src.s_addr;
ip_header.ip_dst = addr_dst.s_addr;
ip_header.checksum = 0;
return add( &ip_header, sizeof( ip_header ) );
}
bool _PACKET_IP::frag( bool more, size_t oset )
{
//
// set packet fragmentation flags
//
IP_HEADER * ip_header = ( IP_HEADER * ) data_buff;
if( more )
ip_header->flags |= htons( IP_FLAG_MORE );
if( oset )
ip_header->flags |= htons( short( oset >> 3 ) );
return true;
}
bool _PACKET_IP::done()
{
//
// set ident, size and checksum
//
IP_HEADER * ip_header = ( IP_HEADER * ) data_buff;
ip_header->size = htons( ( unsigned short ) data_size );
ip_header->checksum = 0;
ip_header->checksum = checksum();
return true;
}
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