Hey,
you will have to extract the packet, set the checksum to zero, calculate the
checksum and put it in his place.
If you need a function for calculating a 16-bit checksum, here you go:
/* int CheckSum16
*
* Helper function whitch calculates a 16 bit checksum of the data.
*/
int CheckSum16 (unsigned char* data, int length) {
unsigned int sum = 0;
unsigned short *s = (unsigned short *)data;
while ( length > 0 ) {
sum += *s;
s++;
length -= 2;
}
while ( sum > 0xffff ) {
sum = ( sum & 0xffff ) + (sum >> 16 );
}
sum = ~sum & 0xffff;
return sum;
}
-----Original Message-----
From: Sergej Kononov [mailto:[EMAIL PROTECTED]
Sent: dinsdag 4 maart 2003 16:11
To: [EMAIL PROTECTED]
Subject: [WinPcap-users] Checksum of a TCP packets
Hi winpcap-users.
Give me please a code of calculation of the control sum of a TCP
package, if i have a pointer to a package: u_char *pPacket;
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