88 lines
2.2 KiB
C
88 lines
2.2 KiB
C
|
/*
|
||
|
|
* IP checksumming functions.
|
||
|
|
* (c) 2008 Gerd Hoffmann <kraxel@redhat.com>
|
||
|
|
*
|
||
|
|
* This program is free software; you can redistribute it and/or modify
|
||
|
|
* it under the terms of the GNU General Public License as published by
|
||
|
|
* the Free Software Foundation; under version 2 of the License.
|
||
|
|
*
|
||
|
|
* This program is distributed in the hope that it will be useful,
|
||
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||
|
|
* GNU General Public License for more details.
|
||
|
|
*
|
||
|
|
* You should have received a copy of the GNU General Public License
|
||
|
|
* along with this program; if not, write to the Free Software
|
||
|
|
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include "hw/hw.h"
|
||
|
|
#include "net.h"
|
||
|
|
|
||
|
|
#define PROTO_TCP 6
|
||
|
|
#define PROTO_UDP 17
|
||
|
|
|
||
|
|
uint32_t net_checksum_add(int len, uint8_t *buf)
|
||
|
|
{
|
||
|
|
uint32_t sum = 0;
|
||
|
|
int i;
|
||
|
|
|
||
|
|
for (i = 0; i < len; i++) {
|
||
|
|
if (i & 1)
|
||
|
|
sum += (uint32_t)buf[i];
|
||
|
|
else
|
||
|
|
sum += (uint32_t)buf[i] << 8;
|
||
|
|
}
|
||
|
|
return sum;
|
||
|
|
}
|
||
|
|
|
||
|
|
uint16_t net_checksum_finish(uint32_t sum)
|
||
|
|
{
|
||
|
|
while (sum>>16)
|
||
|
|
sum = (sum & 0xFFFF)+(sum >> 16);
|
||
|
|
return ~sum;
|
||
|
|
}
|
||
|
|
|
||
|
|
uint16_t net_checksum_tcpudp(uint16_t length, uint16_t proto,
|
||
|
|
uint8_t *addrs, uint8_t *buf)
|
||
|
|
{
|
||
|
|
uint32_t sum = 0;
|
||
|
|
|
||
|
|
sum += net_checksum_add(length, buf); // payload
|
||
|
|
sum += net_checksum_add(8, addrs); // src + dst address
|
||
|
|
sum += proto + length; // protocol & length
|
||
|
|
return net_checksum_finish(sum);
|
||
|
|
}
|
||
|
|
|
||
|
|
void net_checksum_calculate(uint8_t *data, int length)
|
||
|
|
{
|
||
|
|
int hlen, plen, proto, csum_offset;
|
||
|
|
uint16_t csum;
|
||
|
|
|
||
|
|
if ((data[14] & 0xf0) != 0x40)
|
||
|
|
return; /* not IPv4 */
|
||
|
|
hlen = (data[14] & 0x0f) * 4;
|
||
|
|
plen = (data[16] << 8 | data[17]) - hlen;
|
||
|
|
proto = data[23];
|
||
|
|
|
||
|
|
switch (proto) {
|
||
|
|
case PROTO_TCP:
|
||
|
|
csum_offset = 16;
|
||
|
|
break;
|
||
|
|
case PROTO_UDP:
|
||
|
|
csum_offset = 6;
|
||
|
|
break;
|
||
|
|
default:
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
|
||
|
|
if (plen < csum_offset+2)
|
||
|
|
return;
|
||
|
|
|
||
|
|
data[14+hlen+csum_offset] = 0;
|
||
|
|
data[14+hlen+csum_offset+1] = 0;
|
||
|
|
csum = net_checksum_tcpudp(plen, proto, data+14+12, data+14+hlen);
|
||
|
|
data[14+hlen+csum_offset] = csum >> 8;
|
||
|
|
data[14+hlen+csum_offset+1] = csum & 0xff;
|
||
|
|
}
|