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