net/dns/dns_hosts.h

   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
  20 namespace net {
  21   typedef std::pair<std::string, AddressFamily> DnsHostsKey;
  22 };
  23
  24 namespace BASE_HASH_NAMESPACE {
  25 #if defined(COMPILER_GCC)
  26
  27 template<>
  28 struct 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
  37 inline 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
  45 namespace net {
  46
  47 // There are OS-specific variations in how commas in the hosts file behave.
  48 enum 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)
  69 typedef 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.)
  73 typedef 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.
  80 void 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).
  87 void NET_EXPORT_PRIVATE ParseHosts(const std::string& contents,
  88                                    DnsHosts* dns_hosts);
  89
  90 // As above but reads the file pointed to by |path|.
  91 bool 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