2 This file is part of GNUnet.
3 (C) 2010 Christian Grothoff
5 GNUnet is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published
7 by the Free Software Foundation; either version 3, or (at your
8 option) any later version.
10 GNUnet is distributed in the hope that it will be useful, but
11 WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with GNUnet; see the file COPYING. If not, write to the
17 Free Software Foundation, Inc., 59 Temple Place - Suite 330,
18 Boston, MA 02111-1307, USA.
22 * @file vpn/gnunet-vpn-checksum.c
24 * @author Philipp Toelke
27 #include "gnunet-vpn-checksum.h"
30 calculate_checksum_update (uint32_t sum, uint16_t * hdr, short len)
32 for (; len >= 2; len -= 2)
35 sum += *((unsigned char *) hdr);
40 calculate_checksum_end (uint32_t sum)
43 sum = (sum >> 16) + (sum & 0xFFFF);
49 * Calculate the checksum of an IPv4-Header
52 calculate_ip_checksum (uint16_t * hdr, short len)
54 uint32_t sum = calculate_checksum_update (0, hdr, len);
56 return calculate_checksum_end (sum);