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1 | // -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*- |
2 | /* | |
3 | * This file is open source software, licensed to you under the terms | |
4 | * of the Apache License, Version 2.0 (the "License"). See the NOTICE file | |
5 | * distributed with this work for additional information regarding copyright | |
6 | * ownership. You may not use this file except in compliance with the License. | |
7 | * | |
8 | * You may obtain a copy of the License at | |
9 | * | |
10 | * http://www.apache.org/licenses/LICENSE-2.0 | |
11 | * | |
12 | * Unless required by applicable law or agreed to in writing, | |
13 | * software distributed under the License is distributed on an | |
14 | * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY | |
15 | * KIND, either express or implied. See the License for the | |
16 | * specific language governing permissions and limitations | |
17 | * under the License. | |
18 | */ | |
19 | /* | |
20 | * Copyright (C) 2014 Cloudius Systems, Ltd. | |
21 | */ | |
7c673cae FG |
22 | |
23 | #include <arpa/inet.h> | |
24 | #include "net.h" | |
25 | #include "IPChecksum.h" | |
26 | ||
27 | void checksummer::sum(const char* data, size_t len) { | |
28 | auto orig_len = len; | |
29 | if (odd) { | |
30 | csum += uint8_t(*data++); | |
31 | --len; | |
32 | } | |
33 | auto p64 = reinterpret_cast<const uint64_t*>(data); | |
34 | while (len >= 8) { | |
35 | csum += ntohq(*p64++); | |
36 | len -= 8; | |
37 | } | |
38 | auto p16 = reinterpret_cast<const uint16_t*>(p64); | |
39 | while (len >= 2) { | |
40 | csum += ntohs(*p16++); | |
41 | len -= 2; | |
42 | } | |
43 | auto p8 = reinterpret_cast<const uint8_t*>(p16); | |
44 | if (len) { | |
45 | csum += *p8++ << 8; | |
46 | len -= 1; | |
47 | } | |
48 | odd ^= orig_len & 1; | |
49 | } | |
50 | ||
51 | uint16_t checksummer::get() const { | |
52 | __int128 csum1 = (csum & 0xffffffffffffffff) + (csum >> 64); | |
53 | uint64_t csum = (csum1 & 0xffffffffffffffff) + (csum1 >> 64); | |
54 | csum = (csum & 0xffff) + ((csum >> 16) & 0xffff) + ((csum >> 32) & 0xffff) + (csum >> 48); | |
55 | csum = (csum & 0xffff) + (csum >> 16); | |
56 | csum = (csum & 0xffff) + (csum >> 16); | |
57 | return htons(~csum); | |
58 | } | |
59 | ||
60 | void checksummer::sum(const Packet& p) { | |
61 | for (auto&& f : p.fragments()) { | |
62 | sum(f.base, f.size); | |
63 | } | |
64 | } | |
65 | ||
66 | uint16_t ip_checksum(const void* data, size_t len) { | |
67 | checksummer cksum; | |
68 | cksum.sum(reinterpret_cast<const char*>(data), len); | |
69 | return cksum.get(); | |
70 | } |