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
  26 template<>
  27 struct hash<net::DnsHostsKey> {
  28   std::size_t operator()(const net::DnsHostsKey& key) const {
  29     hash<base::StringPiece> string_piece_hash;
  30     return string_piece_hash(key.first) + key.second;
  31   }
  32 };
  33
  34 }  // namespace BASE_HASH_NAMESPACE
  35
  36 namespace net {
  37
  38 // There are OS-specific variations in how commas in the hosts file behave.
  39 enum ParseHostsCommaMode {
  40   // Comma is treated as part of a hostname:
  41   // "127.0.0.1 foo,bar" parses as "foo,bar" mapping to "127.0.0.1".
  42   PARSE_HOSTS_COMMA_IS_TOKEN,
  43
  44   // Comma is treated as a hostname separator:
  45   // "127.0.0.1 foo,bar" parses as "foo" and "bar" both mapping to "127.0.0.1".
  46   PARSE_HOSTS_COMMA_IS_WHITESPACE,
  47 };
  48
  49 // Parsed results of a Hosts file.
  50 //
  51 // Although Hosts files map IP address to a list of domain names, for name
  52 // resolution the desired mapping direction is: domain name to IP address.
  53 // When parsing Hosts, we apply the "first hit" rule as Windows and glibc do.
  54 // With a Hosts file of:
  55 // 300.300.300.300 localhost # bad ip
  56 // 127.0.0.1 localhost
  57 // 10.0.0.1 localhost
  58 // The expected resolution of localhost is 127.0.0.1.
  59 #if !defined(OS_ANDROID)
  60 typedef base::hash_map<DnsHostsKey, IPAddressNumber> DnsHosts;
  61 #else
  62 // Android's hash_map doesn't support ==, so fall back to map.  (Chromium on
  63 // Android doesn't use the built-in DNS resolver anyway, so it's irrelevant.)
  64 typedef std::map<DnsHostsKey, IPAddressNumber> DnsHosts;
  65 #endif
  66
  67 // Parses |contents| (as read from /etc/hosts or equivalent) and stores results
  68 // in |dns_hosts|. Invalid lines are ignored (as in most implementations).
  69 // Overrides the OS-specific default handling of commas, so unittests can test
  70 // both modes.
  71 void NET_EXPORT_PRIVATE ParseHostsWithCommaModeForTesting(
  72     const std::string& contents,
  73     DnsHosts* dns_hosts,
  74     ParseHostsCommaMode comma_mode);
  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 void NET_EXPORT_PRIVATE ParseHosts(const std::string& contents,
  79                                    DnsHosts* dns_hosts);
  80
  81 // As above but reads the file pointed to by |path|.
  82 bool NET_EXPORT_PRIVATE ParseHostsFile(const base::FilePath& path,
  83                                        DnsHosts* dns_hosts);
  84
  85
  86
  87 }  // namespace net
  88
  89 #endif  // NET_DNS_DNS_HOSTS_H_
  90