1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef NET_DNS_DNS_HOSTS_H_
6#define NET_DNS_DNS_HOSTS_H_
7
8#include <map>
9#include <string>
10#include <utility>
11#include <vector>
12
13#include "base/basictypes.h"
14#include "base/containers/hash_tables.h"
15#include "base/files/file_path.h"
16#include "net/base/address_family.h"
17#include "net/base/net_export.h"
18#include "net/base/net_util.h"  // can't forward-declare IPAddressNumber
19
20namespace net {
21  typedef std::pair<std::string, AddressFamily> DnsHostsKey;
22};
23
24namespace BASE_HASH_NAMESPACE {
25#if defined(COMPILER_GCC)
26
27template<>
28struct hash<net::DnsHostsKey> {
29  std::size_t operator()(const net::DnsHostsKey& key) const {
30    hash<base::StringPiece> string_piece_hash;
31    return string_piece_hash(key.first) + key.second;
32  }
33};
34
35#elif defined(COMPILER_MSVC)
36
37inline size_t hash_value(const net::DnsHostsKey& key) {
38  return hash_value(key.first) + key.second;
39}
40
41#endif  // COMPILER
42
43}  // namespace BASE_HASH_NAMESPACE
44
45namespace net {
46
47// There are OS-specific variations in how commas in the hosts file behave.
48enum ParseHostsCommaMode {
49  // Comma is treated as part of a hostname:
50  // "127.0.0.1 foo,bar" parses as "foo,bar" mapping to "127.0.0.1".
51  PARSE_HOSTS_COMMA_IS_TOKEN,
52
53  // Comma is treated as a hostname separator:
54  // "127.0.0.1 foo,bar" parses as "foo" and "bar" both mapping to "127.0.0.1".
55  PARSE_HOSTS_COMMA_IS_WHITESPACE,
56};
57
58// Parsed results of a Hosts file.
59//
60// Although Hosts files map IP address to a list of domain names, for name
61// resolution the desired mapping direction is: domain name to IP address.
62// When parsing Hosts, we apply the "first hit" rule as Windows and glibc do.
63// With a Hosts file of:
64// 300.300.300.300 localhost # bad ip
65// 127.0.0.1 localhost
66// 10.0.0.1 localhost
67// The expected resolution of localhost is 127.0.0.1.
68#if !defined(OS_ANDROID)
69typedef base::hash_map<DnsHostsKey, IPAddressNumber> DnsHosts;
70#else
71// Android's hash_map doesn't support ==, so fall back to map.  (Chromium on
72// Android doesn't use the built-in DNS resolver anyway, so it's irrelevant.)
73typedef std::map<DnsHostsKey, IPAddressNumber> DnsHosts;
74#endif
75
76// Parses |contents| (as read from /etc/hosts or equivalent) and stores results
77// in |dns_hosts|. Invalid lines are ignored (as in most implementations).
78// Overrides the OS-specific default handling of commas, so unittests can test
79// both modes.
80void NET_EXPORT_PRIVATE ParseHostsWithCommaModeForTesting(
81    const std::string& contents,
82    DnsHosts* dns_hosts,
83    ParseHostsCommaMode comma_mode);
84
85// Parses |contents| (as read from /etc/hosts or equivalent) and stores results
86// in |dns_hosts|. Invalid lines are ignored (as in most implementations).
87void NET_EXPORT_PRIVATE ParseHosts(const std::string& contents,
88                                   DnsHosts* dns_hosts);
89
90// As above but reads the file pointed to by |path|.
91bool NET_EXPORT_PRIVATE ParseHostsFile(const base::FilePath& path,
92                                       DnsHosts* dns_hosts);
93
94
95
96}  // namespace net
97
98#endif  // NET_DNS_DNS_HOSTS_H_
99
100