net/dns/dns_config_service_win.cc

   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 #include "net/dns/dns_config_service_win.h"
   6
   7 #include <algorithm>
   8 #include <string>
   9
  10 #include "base/bind.h"
  11 #include "base/callback.h"
  12 #include "base/compiler_specific.h"
  13 #include "base/files/file_path.h"
  14 #include "base/files/file_path_watcher.h"
  15 #include "base/logging.h"
  16 #include "base/memory/scoped_ptr.h"
  17 #include "base/metrics/histogram.h"
  18 #include "base/strings/string_split.h"
  19 #include "base/strings/string_util.h"
  20 #include "base/strings/utf_string_conversions.h"
  21 #include "base/synchronization/lock.h"
  22 #include "base/threading/non_thread_safe.h"
  23 #include "base/threading/thread_restrictions.h"
  24 #include "base/time/time.h"
  25 #include "base/win/object_watcher.h"
  26 #include "base/win/registry.h"
  27 #include "base/win/windows_version.h"
  28 #include "net/base/net_util.h"
  29 #include "net/base/network_change_notifier.h"
  30 #include "net/dns/dns_hosts.h"
  31 #include "net/dns/dns_protocol.h"
  32 #include "net/dns/serial_worker.h"
  33 #include "url/url_canon.h"
  34
  35 #pragma comment(lib, "iphlpapi.lib")
  36
  37 namespace net {
  38
  39 namespace internal {
  40
  41 namespace {
  42
  43 // Interval between retries to parse config. Used only until parsing succeeds.
  44 const int kRetryIntervalSeconds = 5;
  45
  46 // Registry key paths.
  47 const wchar_t* const kTcpipPath =
  48     L"SYSTEM\\CurrentControlSet\\Services\\Tcpip\\Parameters";
  49 const wchar_t* const kTcpip6Path =
  50     L"SYSTEM\\CurrentControlSet\\Services\\Tcpip6\\Parameters";
  51 const wchar_t* const kDnscachePath =
  52     L"SYSTEM\\CurrentControlSet\\Services\\Dnscache\\Parameters";
  53 const wchar_t* const kPolicyPath =
  54     L"SOFTWARE\\Policies\\Microsoft\\Windows NT\\DNSClient";
  55 const wchar_t* const kPrimaryDnsSuffixPath =
  56     L"SOFTWARE\\Policies\\Microsoft\\System\\DNSClient";
  57 const wchar_t* const kNRPTPath =
  58     L"SOFTWARE\\Policies\\Microsoft\\Windows NT\\DNSClient\\DnsPolicyConfig";
  59
  60 enum HostsParseWinResult {
  61   HOSTS_PARSE_WIN_OK = 0,
  62   HOSTS_PARSE_WIN_UNREADABLE_HOSTS_FILE,
  63   HOSTS_PARSE_WIN_COMPUTER_NAME_FAILED,
  64   HOSTS_PARSE_WIN_IPHELPER_FAILED,
  65   HOSTS_PARSE_WIN_BAD_ADDRESS,
  66   HOSTS_PARSE_WIN_MAX  // Bounding values for enumeration.
  67 };
  68
  69 // Convenience for reading values using RegKey.
  70 class RegistryReader : public base::NonThreadSafe {
  71  public:
  72   explicit RegistryReader(const wchar_t* key) {
  73     // Ignoring the result. |key_.Valid()| will catch failures.
  74     key_.Open(HKEY_LOCAL_MACHINE, key, KEY_QUERY_VALUE);
  75   }
  76
  77   bool ReadString(const wchar_t* name,
  78                   DnsSystemSettings::RegString* out) const {
  79     DCHECK(CalledOnValidThread());
  80     out->set = false;
  81     if (!key_.Valid()) {
  82       // Assume that if the |key_| is invalid then the key is missing.
  83       return true;
  84     }
  85     LONG result = key_.ReadValue(name, &out->value);
  86     if (result == ERROR_SUCCESS) {
  87       out->set = true;
  88       return true;
  89     }
  90     return (result == ERROR_FILE_NOT_FOUND);
  91   }
  92
  93   bool ReadDword(const wchar_t* name,
  94                  DnsSystemSettings::RegDword* out) const {
  95     DCHECK(CalledOnValidThread());
  96     out->set = false;
  97     if (!key_.Valid()) {
  98       // Assume that if the |key_| is invalid then the key is missing.
  99       return true;
 100     }
 101     LONG result = key_.ReadValueDW(name, &out->value);
 102     if (result == ERROR_SUCCESS) {
 103       out->set = true;
 104       return true;
 105     }
 106     return (result == ERROR_FILE_NOT_FOUND);
 107   }
 108
 109  private:
 110   base::win::RegKey key_;
 111
 112   DISALLOW_COPY_AND_ASSIGN(RegistryReader);
 113 };
 114
 115 // Wrapper for GetAdaptersAddresses. Returns NULL if failed.
 116 scoped_ptr<IP_ADAPTER_ADDRESSES, base::FreeDeleter> ReadIpHelper(ULONG flags) {
 117   base::ThreadRestrictions::AssertIOAllowed();
 118
 119   scoped_ptr<IP_ADAPTER_ADDRESSES, base::FreeDeleter> out;
 120   ULONG len = 15000;  // As recommended by MSDN for GetAdaptersAddresses.
 121   UINT rv = ERROR_BUFFER_OVERFLOW;
 122   // Try up to three times.
 123   for (unsigned tries = 0; (tries < 3) && (rv == ERROR_BUFFER_OVERFLOW);
 124        tries++) {
 125     out.reset(static_cast<PIP_ADAPTER_ADDRESSES>(malloc(len)));
 126     rv = GetAdaptersAddresses(AF_UNSPEC, flags, NULL, out.get(), &len);
 127   }
 128   if (rv != NO_ERROR)
 129     out.reset();
 130   return out.Pass();
 131 }
 132
 133 // Converts a base::string16 domain name to ASCII, possibly using punycode.
 134 // Returns true if the conversion succeeds and output is not empty. In case of
 135 // failure, |domain| might become dirty.
 136 bool ParseDomainASCII(const base::string16& widestr, std::string* domain) {
 137   DCHECK(domain);
 138   if (widestr.empty())
 139     return false;
 140
 141   // Check if already ASCII.
 142   if (base::IsStringASCII(widestr)) {
 143     *domain = base::UTF16ToASCII(widestr);
 144     return true;
 145   }
 146
 147   // Otherwise try to convert it from IDN to punycode.
 148   const int kInitialBufferSize = 256;
 149   url::RawCanonOutputT<base::char16, kInitialBufferSize> punycode;
 150   if (!url::IDNToASCII(widestr.data(), widestr.length(), &punycode))
 151     return false;
 152
 153   // |punycode_output| should now be ASCII; convert it to a std::string.
 154   // (We could use UTF16ToASCII() instead, but that requires an extra string
 155   // copy. Since ASCII is a subset of UTF8 the following is equivalent).
 156   bool success = base::UTF16ToUTF8(punycode.data(), punycode.length(), domain);
 157   DCHECK(success);
 158   DCHECK(base::IsStringASCII(*domain));
 159   return success && !domain->empty();
 160 }
 161
 162 bool ReadDevolutionSetting(const RegistryReader& reader,
 163                            DnsSystemSettings::DevolutionSetting* setting) {
 164   return reader.ReadDword(L"UseDomainNameDevolution", &setting->enabled) &&
 165          reader.ReadDword(L"DomainNameDevolutionLevel", &setting->level);
 166 }
 167
 168 // Reads DnsSystemSettings from IpHelper and registry.
 169 ConfigParseWinResult ReadSystemSettings(DnsSystemSettings* settings) {
 170   settings->addresses = ReadIpHelper(GAA_FLAG_SKIP_ANYCAST |
 171                                      GAA_FLAG_SKIP_UNICAST |
 172                                      GAA_FLAG_SKIP_MULTICAST |
 173                                      GAA_FLAG_SKIP_FRIENDLY_NAME);
 174   if (!settings->addresses.get())
 175     return CONFIG_PARSE_WIN_READ_IPHELPER;
 176
 177   RegistryReader tcpip_reader(kTcpipPath);
 178   RegistryReader tcpip6_reader(kTcpip6Path);
 179   RegistryReader dnscache_reader(kDnscachePath);
 180   RegistryReader policy_reader(kPolicyPath);
 181   RegistryReader primary_dns_suffix_reader(kPrimaryDnsSuffixPath);
 182
 183   if (!policy_reader.ReadString(L"SearchList",
 184                                 &settings->policy_search_list)) {
 185     return CONFIG_PARSE_WIN_READ_POLICY_SEARCHLIST;
 186   }
 187
 188   if (!tcpip_reader.ReadString(L"SearchList", &settings->tcpip_search_list))
 189     return CONFIG_PARSE_WIN_READ_TCPIP_SEARCHLIST;
 190
 191   if (!tcpip_reader.ReadString(L"Domain", &settings->tcpip_domain))
 192     return CONFIG_PARSE_WIN_READ_DOMAIN;
 193
 194   if (!ReadDevolutionSetting(policy_reader, &settings->policy_devolution))
 195     return CONFIG_PARSE_WIN_READ_POLICY_DEVOLUTION;
 196
 197   if (!ReadDevolutionSetting(dnscache_reader, &settings->dnscache_devolution))
 198     return CONFIG_PARSE_WIN_READ_DNSCACHE_DEVOLUTION;
 199
 200   if (!ReadDevolutionSetting(tcpip_reader, &settings->tcpip_devolution))
 201     return CONFIG_PARSE_WIN_READ_TCPIP_DEVOLUTION;
 202
 203   if (!policy_reader.ReadDword(L"AppendToMultiLabelName",
 204                                &settings->append_to_multi_label_name)) {
 205     return CONFIG_PARSE_WIN_READ_APPEND_MULTILABEL;
 206   }
 207
 208   if (!primary_dns_suffix_reader.ReadString(L"PrimaryDnsSuffix",
 209                                             &settings->primary_dns_suffix)) {
 210     return CONFIG_PARSE_WIN_READ_PRIMARY_SUFFIX;
 211   }
 212
 213   base::win::RegistryKeyIterator nrpt_rules(HKEY_LOCAL_MACHINE, kNRPTPath);
 214   settings->have_name_resolution_policy = (nrpt_rules.SubkeyCount() > 0);
 215
 216   return CONFIG_PARSE_WIN_OK;
 217 }
 218
 219 // Default address of "localhost" and local computer name can be overridden
 220 // by the HOSTS file, but if it's not there, then we need to fill it in.
 221 HostsParseWinResult AddLocalhostEntries(DnsHosts* hosts) {
 222   const unsigned char kIPv4Localhost[] = { 127, 0, 0, 1 };
 223   const unsigned char kIPv6Localhost[] = { 0, 0, 0, 0, 0, 0, 0, 0,
 224                                            0, 0, 0, 0, 0, 0, 0, 1 };
 225   IPAddressNumber loopback_ipv4(kIPv4Localhost,
 226                                 kIPv4Localhost + arraysize(kIPv4Localhost));
 227   IPAddressNumber loopback_ipv6(kIPv6Localhost,
 228                                 kIPv6Localhost + arraysize(kIPv6Localhost));
 229
 230   // This does not override any pre-existing entries from the HOSTS file.
 231   hosts->insert(std::make_pair(DnsHostsKey("localhost", ADDRESS_FAMILY_IPV4),
 232                                loopback_ipv4));
 233   hosts->insert(std::make_pair(DnsHostsKey("localhost", ADDRESS_FAMILY_IPV6),
 234                                loopback_ipv6));
 235
 236   WCHAR buffer[MAX_PATH];
 237   DWORD size = MAX_PATH;
 238   std::string localname;
 239   if (!GetComputerNameExW(ComputerNameDnsHostname, buffer, &size) ||
 240       !ParseDomainASCII(buffer, &localname)) {
 241     return HOSTS_PARSE_WIN_COMPUTER_NAME_FAILED;
 242   }
 243   StringToLowerASCII(&localname);
 244
 245   bool have_ipv4 =
 246       hosts->count(DnsHostsKey(localname, ADDRESS_FAMILY_IPV4)) > 0;
 247   bool have_ipv6 =
 248       hosts->count(DnsHostsKey(localname, ADDRESS_FAMILY_IPV6)) > 0;
 249
 250   if (have_ipv4 && have_ipv6)
 251     return HOSTS_PARSE_WIN_OK;
 252
 253   scoped_ptr<IP_ADAPTER_ADDRESSES, base::FreeDeleter> addresses =
 254       ReadIpHelper(GAA_FLAG_SKIP_ANYCAST |
 255                    GAA_FLAG_SKIP_DNS_SERVER |
 256                    GAA_FLAG_SKIP_MULTICAST |
 257                    GAA_FLAG_SKIP_FRIENDLY_NAME);
 258   if (!addresses.get())
 259     return HOSTS_PARSE_WIN_IPHELPER_FAILED;
 260
 261   // The order of adapters is the network binding order, so stick to the
 262   // first good adapter for each family.
 263   for (const IP_ADAPTER_ADDRESSES* adapter = addresses.get();
 264        adapter != NULL && (!have_ipv4 || !have_ipv6);
 265        adapter = adapter->Next) {
 266     if (adapter->OperStatus != IfOperStatusUp)
 267       continue;
 268     if (adapter->IfType == IF_TYPE_SOFTWARE_LOOPBACK)
 269       continue;
 270
 271     for (const IP_ADAPTER_UNICAST_ADDRESS* address =
 272              adapter->FirstUnicastAddress;
 273          address != NULL;
 274          address = address->Next) {
 275       IPEndPoint ipe;
 276       if (!ipe.FromSockAddr(address->Address.lpSockaddr,
 277                             address->Address.iSockaddrLength)) {
 278         return HOSTS_PARSE_WIN_BAD_ADDRESS;
 279       }
 280       if (!have_ipv4 && (ipe.GetFamily() == ADDRESS_FAMILY_IPV4)) {
 281         have_ipv4 = true;
 282         (*hosts)[DnsHostsKey(localname, ADDRESS_FAMILY_IPV4)] = ipe.address();
 283       } else if (!have_ipv6 && (ipe.GetFamily() == ADDRESS_FAMILY_IPV6)) {
 284         have_ipv6 = true;
 285         (*hosts)[DnsHostsKey(localname, ADDRESS_FAMILY_IPV6)] = ipe.address();
 286       }
 287     }
 288   }
 289   return HOSTS_PARSE_WIN_OK;
 290 }
 291
 292 // Watches a single registry key for changes.
 293 class RegistryWatcher : public base::win::ObjectWatcher::Delegate,
 294                         public base::NonThreadSafe {
 295  public:
 296   typedef base::Callback<void(bool succeeded)> CallbackType;
 297   RegistryWatcher() {}
 298
 299   bool Watch(const wchar_t* key, const CallbackType& callback) {
 300     DCHECK(CalledOnValidThread());
 301     DCHECK(!callback.is_null());
 302     DCHECK(callback_.is_null());
 303     callback_ = callback;
 304     if (key_.Open(HKEY_LOCAL_MACHINE, key, KEY_NOTIFY) != ERROR_SUCCESS)
 305       return false;
 306     if (key_.StartWatching() != ERROR_SUCCESS)
 307       return false;
 308     if (!watcher_.StartWatching(key_.watch_event(), this))
 309       return false;
 310     return true;
 311   }
 312
 313   virtual void OnObjectSignaled(HANDLE object) OVERRIDE {
 314     DCHECK(CalledOnValidThread());
 315     bool succeeded = (key_.StartWatching() == ERROR_SUCCESS) &&
 316                       watcher_.StartWatching(key_.watch_event(), this);
 317     if (!succeeded && key_.Valid()) {
 318       watcher_.StopWatching();
 319       key_.StopWatching();
 320       key_.Close();
 321     }
 322     if (!callback_.is_null())
 323       callback_.Run(succeeded);
 324   }
 325
 326  private:
 327   CallbackType callback_;
 328   base::win::RegKey key_;
 329   base::win::ObjectWatcher watcher_;
 330
 331   DISALLOW_COPY_AND_ASSIGN(RegistryWatcher);
 332 };
 333
 334 // Returns true iff |address| is DNS address from IPv6 stateless discovery,
 335 // i.e., matches fec0:0:0:ffff::{1,2,3}.
 336 // http://tools.ietf.org/html/draft-ietf-ipngwg-dns-discovery
 337 bool IsStatelessDiscoveryAddress(const IPAddressNumber& address) {
 338   if (address.size() != kIPv6AddressSize)
 339     return false;
 340   const uint8 kPrefix[] = {
 341       0xfe, 0xc0, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff,
 342       0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
 343   };
 344   return std::equal(kPrefix, kPrefix + arraysize(kPrefix),
 345                     address.begin()) && (address.back() < 4);
 346 }
 347
 348 // Returns the path to the HOSTS file.
 349 base::FilePath GetHostsPath() {
 350   TCHAR buffer[MAX_PATH];
 351   UINT rc = GetSystemDirectory(buffer, MAX_PATH);
 352   DCHECK(0 < rc && rc < MAX_PATH);
 353   return base::FilePath(buffer).Append(
 354       FILE_PATH_LITERAL("drivers\\etc\\hosts"));
 355 }
 356
 357 void ConfigureSuffixSearch(const DnsSystemSettings& settings,
 358                            DnsConfig* config) {
 359   // SearchList takes precedence, so check it first.
 360   if (settings.policy_search_list.set) {
 361     std::vector<std::string> search;
 362     if (ParseSearchList(settings.policy_search_list.value, &search)) {
 363       config->search.swap(search);
 364       return;
 365     }
 366     // Even if invalid, the policy disables the user-specified setting below.
 367   } else if (settings.tcpip_search_list.set) {
 368     std::vector<std::string> search;
 369     if (ParseSearchList(settings.tcpip_search_list.value, &search)) {
 370       config->search.swap(search);
 371       return;
 372     }
 373   }
 374
 375   // In absence of explicit search list, suffix search is:
 376   // [primary suffix, connection-specific suffix, devolution of primary suffix].
 377   // Primary suffix can be set by policy (primary_dns_suffix) or
 378   // user setting (tcpip_domain).
 379   //
 380   // The policy (primary_dns_suffix) can be edited via Group Policy Editor
 381   // (gpedit.msc) at Local Computer Policy => Computer Configuration
 382   // => Administrative Template => Network => DNS Client => Primary DNS Suffix.
 383   //
 384   // The user setting (tcpip_domain) can be configurred at Computer Name in
 385   // System Settings
 386   std::string primary_suffix;
 387   if ((settings.primary_dns_suffix.set &&
 388        ParseDomainASCII(settings.primary_dns_suffix.value, &primary_suffix)) ||
 389       (settings.tcpip_domain.set &&
 390        ParseDomainASCII(settings.tcpip_domain.value, &primary_suffix))) {
 391     // Primary suffix goes in front.
 392     config->search.insert(config->search.begin(), primary_suffix);
 393   } else {
 394     return;  // No primary suffix, hence no devolution.
 395   }
 396
 397   // Devolution is determined by precedence: policy > dnscache > tcpip.
 398   // |enabled|: UseDomainNameDevolution and |level|: DomainNameDevolutionLevel
 399   // are overridden independently.
 400   DnsSystemSettings::DevolutionSetting devolution = settings.policy_devolution;
 401
 402   if (!devolution.enabled.set)
 403     devolution.enabled = settings.dnscache_devolution.enabled;
 404   if (!devolution.enabled.set)
 405     devolution.enabled = settings.tcpip_devolution.enabled;
 406   if (devolution.enabled.set && (devolution.enabled.value == 0))
 407     return;  // Devolution disabled.
 408
 409   // By default devolution is enabled.
 410
 411   if (!devolution.level.set)
 412     devolution.level = settings.dnscache_devolution.level;
 413   if (!devolution.level.set)
 414     devolution.level = settings.tcpip_devolution.level;
 415
 416   // After the recent update, Windows will try to determine a safe default
 417   // value by comparing the forest root domain (FRD) to the primary suffix.
 418   // See http://support.microsoft.com/kb/957579 for details.
 419   // For now, if the level is not set, we disable devolution, assuming that
 420   // we will fallback to the system getaddrinfo anyway. This might cause
 421   // performance loss for resolutions which depend on the system default
 422   // devolution setting.
 423   //
 424   // If the level is explicitly set below 2, devolution is disabled.
 425   if (!devolution.level.set || devolution.level.value < 2)
 426     return;  // Devolution disabled.
 427
 428   // Devolve the primary suffix. This naive logic matches the observed
 429   // behavior (see also ParseSearchList). If a suffix is not valid, it will be
 430   // discarded when the fully-qualified name is converted to DNS format.
 431
 432   unsigned num_dots = std::count(primary_suffix.begin(),
 433                                  primary_suffix.end(), '.');
 434
 435   for (size_t offset = 0; num_dots >= devolution.level.value; --num_dots) {
 436     offset = primary_suffix.find('.', offset + 1);
 437     config->search.push_back(primary_suffix.substr(offset + 1));
 438   }
 439 }
 440
 441 }  // namespace
 442
 443 bool ParseSearchList(const base::string16& value,
 444                      std::vector<std::string>* output) {
 445   DCHECK(output);
 446   if (value.empty())
 447     return false;
 448
 449   output->clear();
 450
 451   // If the list includes an empty hostname (",," or ", ,"), it is terminated.
 452   // Although nslookup and network connection property tab ignore such
 453   // fragments ("a,b,,c" becomes ["a", "b", "c"]), our reference is getaddrinfo
 454   // (which sees ["a", "b"]). WMI queries also return a matching search list.
 455   std::vector<base::string16> woutput;
 456   base::SplitString(value, ',', &woutput);
 457   for (size_t i = 0; i < woutput.size(); ++i) {
 458     // Convert non-ASCII to punycode, although getaddrinfo does not properly
 459     // handle such suffixes.
 460     const base::string16& t = woutput[i];
 461     std::string parsed;
 462     if (!ParseDomainASCII(t, &parsed))
 463       break;
 464     output->push_back(parsed);
 465   }
 466   return !output->empty();
 467 }
 468
 469 ConfigParseWinResult ConvertSettingsToDnsConfig(
 470     const DnsSystemSettings& settings,
 471     DnsConfig* config) {
 472   *config = DnsConfig();
 473
 474   // Use GetAdapterAddresses to get effective DNS server order and
 475   // connection-specific DNS suffix. Ignore disconnected and loopback adapters.
 476   // The order of adapters is the network binding order, so stick to the
 477   // first good adapter.
 478   for (const IP_ADAPTER_ADDRESSES* adapter = settings.addresses.get();
 479        adapter != NULL && config->nameservers.empty();
 480        adapter = adapter->Next) {
 481     if (adapter->OperStatus != IfOperStatusUp)
 482       continue;
 483     if (adapter->IfType == IF_TYPE_SOFTWARE_LOOPBACK)
 484       continue;
 485
 486     for (const IP_ADAPTER_DNS_SERVER_ADDRESS* address =
 487              adapter->FirstDnsServerAddress;
 488          address != NULL;
 489          address = address->Next) {
 490       IPEndPoint ipe;
 491       if (ipe.FromSockAddr(address->Address.lpSockaddr,
 492                            address->Address.iSockaddrLength)) {
 493         if (IsStatelessDiscoveryAddress(ipe.address()))
 494           continue;
 495         // Override unset port.
 496         if (!ipe.port())
 497           ipe = IPEndPoint(ipe.address(), dns_protocol::kDefaultPort);
 498         config->nameservers.push_back(ipe);
 499       } else {
 500         return CONFIG_PARSE_WIN_BAD_ADDRESS;
 501       }
 502     }
 503
 504     // IP_ADAPTER_ADDRESSES in Vista+ has a search list at |FirstDnsSuffix|,
 505     // but it came up empty in all trials.
 506     // |DnsSuffix| stores the effective connection-specific suffix, which is
 507     // obtained via DHCP (regkey: Tcpip\Parameters\Interfaces\{XXX}\DhcpDomain)
 508     // or specified by the user (regkey: Tcpip\Parameters\Domain).
 509     std::string dns_suffix;
 510     if (ParseDomainASCII(adapter->DnsSuffix, &dns_suffix))
 511       config->search.push_back(dns_suffix);
 512   }
 513
 514   if (config->nameservers.empty())
 515     return CONFIG_PARSE_WIN_NO_NAMESERVERS;  // No point continuing.
 516
 517   // Windows always tries a multi-label name "as is" before using suffixes.
 518   config->ndots = 1;
 519
 520   if (!settings.append_to_multi_label_name.set) {
 521     // The default setting is true for XP, false for Vista+.
 522     if (base::win::GetVersion() >= base::win::VERSION_VISTA) {
 523       config->append_to_multi_label_name = false;
 524     } else {
 525       config->append_to_multi_label_name = true;
 526     }
 527   } else {
 528     config->append_to_multi_label_name =
 529         (settings.append_to_multi_label_name.value != 0);
 530   }
 531
 532   ConfigParseWinResult result = CONFIG_PARSE_WIN_OK;
 533   if (settings.have_name_resolution_policy) {
 534     config->unhandled_options = true;
 535     // TODO(szym): only set this to true if NRPT has DirectAccess rules.
 536     config->use_local_ipv6 = true;
 537     result = CONFIG_PARSE_WIN_UNHANDLED_OPTIONS;
 538   }
 539
 540   ConfigureSuffixSearch(settings, config);
 541   return result;
 542 }
 543
 544 // Watches registry and HOSTS file for changes. Must live on a thread which
 545 // allows IO.
 546 class DnsConfigServiceWin::Watcher
 547     : public NetworkChangeNotifier::IPAddressObserver {
 548  public:
 549   explicit Watcher(DnsConfigServiceWin* service) : service_(service) {}
 550   ~Watcher() {
 551     NetworkChangeNotifier::RemoveIPAddressObserver(this);
 552   }
 553
 554   bool Watch() {
 555     RegistryWatcher::CallbackType callback =
 556         base::Bind(&DnsConfigServiceWin::OnConfigChanged,
 557                    base::Unretained(service_));
 558
 559     bool success = true;
 560
 561     // The Tcpip key must be present.
 562     if (!tcpip_watcher_.Watch(kTcpipPath, callback)) {
 563       LOG(ERROR) << "DNS registry watch failed to start.";
 564       success = false;
 565       UMA_HISTOGRAM_ENUMERATION("AsyncDNS.WatchStatus",
 566                                 DNS_CONFIG_WATCH_FAILED_TO_START_CONFIG,
 567                                 DNS_CONFIG_WATCH_MAX);
 568     }
 569
 570     // Watch for IPv6 nameservers.
 571     tcpip6_watcher_.Watch(kTcpip6Path, callback);
 572
 573     // DNS suffix search list and devolution can be configured via group
 574     // policy which sets this registry key. If the key is missing, the policy
 575     // does not apply, and the DNS client uses Tcpip and Dnscache settings.
 576     // If a policy is installed, DnsConfigService will need to be restarted.
 577     // BUG=99509
 578
 579     dnscache_watcher_.Watch(kDnscachePath, callback);
 580     policy_watcher_.Watch(kPolicyPath, callback);
 581
 582     if (!hosts_watcher_.Watch(GetHostsPath(), false,
 583                               base::Bind(&Watcher::OnHostsChanged,
 584                                          base::Unretained(this)))) {
 585       UMA_HISTOGRAM_ENUMERATION("AsyncDNS.WatchStatus",
 586                                 DNS_CONFIG_WATCH_FAILED_TO_START_HOSTS,
 587                                 DNS_CONFIG_WATCH_MAX);
 588       LOG(ERROR) << "DNS hosts watch failed to start.";
 589       success = false;
 590     } else {
 591       // Also need to observe changes to local non-loopback IP for DnsHosts.
 592       NetworkChangeNotifier::AddIPAddressObserver(this);
 593     }
 594     return success;
 595   }
 596
 597  private:
 598   void OnHostsChanged(const base::FilePath& path, bool error) {
 599     if (error)
 600       NetworkChangeNotifier::RemoveIPAddressObserver(this);
 601     service_->OnHostsChanged(!error);
 602   }
 603
 604   // NetworkChangeNotifier::IPAddressObserver:
 605   virtual void OnIPAddressChanged() OVERRIDE {
 606     // Need to update non-loopback IP of local host.
 607     service_->OnHostsChanged(true);
 608   }
 609
 610   DnsConfigServiceWin* service_;
 611
 612   RegistryWatcher tcpip_watcher_;
 613   RegistryWatcher tcpip6_watcher_;
 614   RegistryWatcher dnscache_watcher_;
 615   RegistryWatcher policy_watcher_;
 616   base::FilePathWatcher hosts_watcher_;
 617
 618   DISALLOW_COPY_AND_ASSIGN(Watcher);
 619 };
 620
 621 // Reads config from registry and IpHelper. All work performed on WorkerPool.
 622 class DnsConfigServiceWin::ConfigReader : public SerialWorker {
 623  public:
 624   explicit ConfigReader(DnsConfigServiceWin* service)
 625       : service_(service),
 626         success_(false) {}
 627
 628  private:
 629   virtual ~ConfigReader() {}
 630
 631   virtual void DoWork() OVERRIDE {
 632     // Should be called on WorkerPool.
 633     base::TimeTicks start_time = base::TimeTicks::Now();
 634     DnsSystemSettings settings = {};
 635     ConfigParseWinResult result = ReadSystemSettings(&settings);
 636     if (result == CONFIG_PARSE_WIN_OK)
 637       result = ConvertSettingsToDnsConfig(settings, &dns_config_);
 638     success_ = (result == CONFIG_PARSE_WIN_OK ||
 639                 result == CONFIG_PARSE_WIN_UNHANDLED_OPTIONS);
 640     UMA_HISTOGRAM_ENUMERATION("AsyncDNS.ConfigParseWin",
 641                               result, CONFIG_PARSE_WIN_MAX);
 642     UMA_HISTOGRAM_BOOLEAN("AsyncDNS.ConfigParseResult", success_);
 643     UMA_HISTOGRAM_TIMES("AsyncDNS.ConfigParseDuration",
 644                         base::TimeTicks::Now() - start_time);
 645   }
 646
 647   virtual void OnWorkFinished() OVERRIDE {
 648     DCHECK(loop()->BelongsToCurrentThread());
 649     DCHECK(!IsCancelled());
 650     if (success_) {
 651       service_->OnConfigRead(dns_config_);
 652     } else {
 653       LOG(WARNING) << "Failed to read DnsConfig.";
 654       // Try again in a while in case DnsConfigWatcher missed the signal.
 655       base::MessageLoop::current()->PostDelayedTask(
 656           FROM_HERE,
 657           base::Bind(&ConfigReader::WorkNow, this),
 658           base::TimeDelta::FromSeconds(kRetryIntervalSeconds));
 659     }
 660   }
 661
 662   DnsConfigServiceWin* service_;
 663   // Written in DoWork(), read in OnWorkFinished(). No locking required.
 664   DnsConfig dns_config_;
 665   bool success_;
 666 };
 667
 668 // Reads hosts from HOSTS file and fills in localhost and local computer name if
 669 // necessary. All work performed on WorkerPool.
 670 class DnsConfigServiceWin::HostsReader : public SerialWorker {
 671  public:
 672   explicit HostsReader(DnsConfigServiceWin* service)
 673       : path_(GetHostsPath()),
 674         service_(service),
 675         success_(false) {
 676   }
 677
 678  private:
 679   virtual ~HostsReader() {}
 680
 681   virtual void DoWork() OVERRIDE {
 682     base::TimeTicks start_time = base::TimeTicks::Now();
 683     HostsParseWinResult result = HOSTS_PARSE_WIN_UNREADABLE_HOSTS_FILE;
 684     if (ParseHostsFile(path_, &hosts_))
 685       result = AddLocalhostEntries(&hosts_);
 686     success_ = (result == HOSTS_PARSE_WIN_OK);
 687     UMA_HISTOGRAM_ENUMERATION("AsyncDNS.HostsParseWin",
 688                               result, HOSTS_PARSE_WIN_MAX);
 689     UMA_HISTOGRAM_BOOLEAN("AsyncDNS.HostParseResult", success_);
 690     UMA_HISTOGRAM_TIMES("AsyncDNS.HostsParseDuration",
 691                         base::TimeTicks::Now() - start_time);
 692   }
 693
 694   virtual void OnWorkFinished() OVERRIDE {
 695     DCHECK(loop()->BelongsToCurrentThread());
 696     if (success_) {
 697       service_->OnHostsRead(hosts_);
 698     } else {
 699       LOG(WARNING) << "Failed to read DnsHosts.";
 700     }
 701   }
 702
 703   const base::FilePath path_;
 704   DnsConfigServiceWin* service_;
 705   // Written in DoWork, read in OnWorkFinished, no locking necessary.
 706   DnsHosts hosts_;
 707   bool success_;
 708
 709   DISALLOW_COPY_AND_ASSIGN(HostsReader);
 710 };
 711
 712 DnsConfigServiceWin::DnsConfigServiceWin()
 713     : config_reader_(new ConfigReader(this)),
 714       hosts_reader_(new HostsReader(this)) {}
 715
 716 DnsConfigServiceWin::~DnsConfigServiceWin() {
 717   config_reader_->Cancel();
 718   hosts_reader_->Cancel();
 719 }
 720
 721 void DnsConfigServiceWin::ReadNow() {
 722   config_reader_->WorkNow();
 723   hosts_reader_->WorkNow();
 724 }
 725
 726 bool DnsConfigServiceWin::StartWatching() {
 727   // TODO(szym): re-start watcher if that makes sense. http://crbug.com/116139
 728   watcher_.reset(new Watcher(this));
 729   UMA_HISTOGRAM_ENUMERATION("AsyncDNS.WatchStatus", DNS_CONFIG_WATCH_STARTED,
 730                             DNS_CONFIG_WATCH_MAX);
 731   return watcher_->Watch();
 732 }
 733
 734 void DnsConfigServiceWin::OnConfigChanged(bool succeeded) {
 735   InvalidateConfig();
 736   if (succeeded) {
 737     config_reader_->WorkNow();
 738   } else {
 739     LOG(ERROR) << "DNS config watch failed.";
 740     set_watch_failed(true);
 741     UMA_HISTOGRAM_ENUMERATION("AsyncDNS.WatchStatus",
 742                               DNS_CONFIG_WATCH_FAILED_CONFIG,
 743                               DNS_CONFIG_WATCH_MAX);
 744   }
 745 }
 746
 747 void DnsConfigServiceWin::OnHostsChanged(bool succeeded) {
 748   InvalidateHosts();
 749   if (succeeded) {
 750     hosts_reader_->WorkNow();
 751   } else {
 752     LOG(ERROR) << "DNS hosts watch failed.";
 753     set_watch_failed(true);
 754     UMA_HISTOGRAM_ENUMERATION("AsyncDNS.WatchStatus",
 755                               DNS_CONFIG_WATCH_FAILED_HOSTS,
 756                               DNS_CONFIG_WATCH_MAX);
 757   }
 758 }
 759
 760 }  // namespace internal
 761
 762 // static
 763 scoped_ptr<DnsConfigService> DnsConfigService::CreateSystemService() {
 764   return scoped_ptr<DnsConfigService>(new internal::DnsConfigServiceWin());
 765 }
 766
 767 }  // namespace net