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_CONFIG_SERVICE_H_ 6 #define NET_DNS_DNS_CONFIG_SERVICE_H_ 7 8 #include <map> 9 #include <string> 10 #include <vector> 11 12 #include "base/gtest_prod_util.h" 13 #include "base/memory/scoped_ptr.h" 14 #include "base/threading/non_thread_safe.h" 15 #include "base/time/time.h" 16 #include "base/timer/timer.h" 17 // Needed on shared build with MSVS2010 to avoid multiple definitions of 18 // std::vector<IPEndPoint>. 19 #include "net/base/address_list.h" 20 #include "net/base/ip_endpoint.h" // win requires size of IPEndPoint 21 #include "net/base/net_export.h" 22 #include "net/dns/dns_hosts.h" 23 24 namespace base { 25 class Value; 26 } 27 28 namespace net { 29 30 // Always use 1 second timeout (followed by binary exponential backoff). 31 // TODO(szym): Remove code which reads timeout from system. 32 const unsigned kDnsTimeoutSeconds = 1; 33 34 // DnsConfig stores configuration of the system resolver. 35 struct NET_EXPORT_PRIVATE DnsConfig { 36 DnsConfig(); 37 virtual ~DnsConfig(); 38 39 bool Equals(const DnsConfig& d) const; 40 41 bool EqualsIgnoreHosts(const DnsConfig& d) const; 42 43 void CopyIgnoreHosts(const DnsConfig& src); 44 45 // Returns a Value representation of |this|. Caller takes ownership of the 46 // returned Value. For performance reasons, the Value only contains the 47 // number of hosts rather than the full list. 48 base::Value* ToValue() const; 49 50 bool IsValid() const { 51 return !nameservers.empty(); 52 } 53 54 // List of name server addresses. 55 std::vector<IPEndPoint> nameservers; 56 // Suffix search list; used on first lookup when number of dots in given name 57 // is less than |ndots|. 58 std::vector<std::string> search; 59 60 DnsHosts hosts; 61 62 // AppendToMultiLabelName: is suffix search performed for multi-label names? 63 // True, except on Windows where it can be configured. 64 bool append_to_multi_label_name; 65 66 // Indicates that source port randomization is required. This uses additional 67 // resources on some platforms. 68 bool randomize_ports; 69 70 // Resolver options; see man resolv.conf. 71 72 // Minimum number of dots before global resolution precedes |search|. 73 int ndots; 74 // Time between retransmissions, see res_state.retrans. 75 base::TimeDelta timeout; 76 // Maximum number of attempts, see res_state.retry. 77 int attempts; 78 // Round robin entries in |nameservers| for subsequent requests. 79 bool rotate; 80 // Enable EDNS0 extensions. 81 bool edns0; 82 }; 83 84 85 // Service for reading system DNS settings, on demand or when signalled by 86 // internal watchers and NetworkChangeNotifier. 87 class NET_EXPORT_PRIVATE DnsConfigService 88 : NON_EXPORTED_BASE(public base::NonThreadSafe) { 89 public: 90 // Callback interface for the client, called on the same thread as 91 // ReadConfig() and WatchConfig(). 92 typedef base::Callback<void(const DnsConfig& config)> CallbackType; 93 94 // Creates the platform-specific DnsConfigService. 95 static scoped_ptr<DnsConfigService> CreateSystemService(); 96 97 DnsConfigService(); 98 virtual ~DnsConfigService(); 99 100 // Attempts to read the configuration. Will run |callback| when succeeded. 101 // Can be called at most once. 102 void ReadConfig(const CallbackType& callback); 103 104 // Registers systems watchers. Will attempt to read config after watch starts, 105 // but only if watchers started successfully. Will run |callback| iff config 106 // changes from last call or has to be withdrawn. Can be called at most once. 107 // Might require MessageLoopForIO. 108 void WatchConfig(const CallbackType& callback); 109 110 protected: 111 enum WatchStatus { 112 DNS_CONFIG_WATCH_STARTED = 0, 113 DNS_CONFIG_WATCH_FAILED_TO_START_CONFIG, 114 DNS_CONFIG_WATCH_FAILED_TO_START_HOSTS, 115 DNS_CONFIG_WATCH_FAILED_CONFIG, 116 DNS_CONFIG_WATCH_FAILED_HOSTS, 117 DNS_CONFIG_WATCH_MAX, 118 }; 119 120 // Immediately attempts to read the current configuration. 121 virtual void ReadNow() = 0; 122 // Registers system watchers. Returns true iff succeeds. 123 virtual bool StartWatching() = 0; 124 125 // Called when the current config (except hosts) has changed. 126 void InvalidateConfig(); 127 // Called when the current hosts have changed. 128 void InvalidateHosts(); 129 130 // Called with new config. |config|.hosts is ignored. 131 void OnConfigRead(const DnsConfig& config); 132 // Called with new hosts. Rest of the config is assumed unchanged. 133 void OnHostsRead(const DnsHosts& hosts); 134 135 void set_watch_failed(bool value) { watch_failed_ = value; } 136 137 private: 138 // The timer counts from the last Invalidate* until complete config is read. 139 void StartTimer(); 140 void OnTimeout(); 141 // Called when the config becomes complete. Stops the timer. 142 void OnCompleteConfig(); 143 144 CallbackType callback_; 145 146 DnsConfig dns_config_; 147 148 // True if any of the necessary watchers failed. In that case, the service 149 // will communicate changes via OnTimeout, but will only send empty DnsConfig. 150 bool watch_failed_; 151 // True after On*Read, before Invalidate*. Tells if the config is complete. 152 bool have_config_; 153 bool have_hosts_; 154 // True if receiver needs to be updated when the config becomes complete. 155 bool need_update_; 156 // True if the last config sent was empty (instead of |dns_config_|). 157 // Set when |timer_| expires. 158 bool last_sent_empty_; 159 160 // Initialized and updated on Invalidate* call. 161 base::TimeTicks last_invalidate_config_time_; 162 base::TimeTicks last_invalidate_hosts_time_; 163 // Initialized and updated when |timer_| expires. 164 base::TimeTicks last_sent_empty_time_; 165 166 // Started in Invalidate*, cleared in On*Read. 167 base::OneShotTimer<DnsConfigService> timer_; 168 169 DISALLOW_COPY_AND_ASSIGN(DnsConfigService); 170 }; 171 172 } // namespace net 173 174 #endif // NET_DNS_DNS_CONFIG_SERVICE_H_ 175
