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// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
/*
* This file is open source software, licensed to you under the terms
* of the Apache License, Version 2.0 (the "License"). See the NOTICE file
* distributed with this work for additional information regarding copyright
* ownership. You may not use this file except in compliance with the License.
*
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
/*
* Copyright (C) 2014 Cloudius Systems, Ltd.
*/
#include <arpa/inet.h>
#include "net.h"
#include "IPChecksum.h"
void checksummer::sum(const char* data, size_t len) {
auto orig_len = len;
if (odd) {
csum += uint8_t(*data++);
--len;
}
auto p64 = reinterpret_cast<const uint64_t*>(data);
while (len >= 8) {
csum += ntohq(*p64++);
len -= 8;
}
auto p16 = reinterpret_cast<const uint16_t*>(p64);
while (len >= 2) {
csum += ntohs(*p16++);
len -= 2;
}
auto p8 = reinterpret_cast<const uint8_t*>(p16);
if (len) {
csum += *p8++ << 8;
len -= 1;
}
odd ^= orig_len & 1;
}
uint16_t checksummer::get() const {
__int128 csum1 = (csum & 0xffffffffffffffff) + (csum >> 64);
uint64_t csum = (csum1 & 0xffffffffffffffff) + (csum1 >> 64);
csum = (csum & 0xffff) + ((csum >> 16) & 0xffff) + ((csum >> 32) & 0xffff) + (csum >> 48);
csum = (csum & 0xffff) + (csum >> 16);
csum = (csum & 0xffff) + (csum >> 16);
return htons(~csum);
}
void checksummer::sum(const Packet& p) {
for (auto&& f : p.fragments()) {
sum(f.base, f.size);
}
}
uint16_t ip_checksum(const void* data, size_t len) {
checksummer cksum;
cksum.sum(reinterpret_cast<const char*>(data), len);
return cksum.get();
}
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