From 7200ac3c7c8eefe574193b49eeff09f120e11ec7 Mon Sep 17 00:00:00 2001 From: Mark McLoughlin Date: Thu, 22 Oct 2009 17:49:03 +0100 Subject: net: move net-checksum.c under net/ Also add a new net/checksum.h header Signed-off-by: Mark McLoughlin Signed-off-by: Anthony Liguori --- net/checksum.c | 85 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 85 insertions(+) create mode 100644 net/checksum.c (limited to 'net/checksum.c') diff --git a/net/checksum.c b/net/checksum.c new file mode 100644 index 0000000000..4046932e9d --- /dev/null +++ b/net/checksum.c @@ -0,0 +1,85 @@ +/* + * IP checksumming functions. + * (c) 2008 Gerd Hoffmann + * + * 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, see . + */ + +#include "net/checksum.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; +} -- cgit v1.2.1