[net/dns] Isolate DnsConfigWatcher from DnsConfigService.

net/dns/dns_config_watcher_win.cc

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "net/dns/dns_config_watcher.h"
+
+#include <winsock2.h>
+
+#include <string>
+
+#include "base/bind.h"
+#include "base/callback.h"
+#include "base/compiler_specific.h"
+#include "base/file_path.h"
+#include "base/logging.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/synchronization/lock.h"
+#include "base/threading/non_thread_safe.h"
+#include "base/win/object_watcher.h"
+#include "base/win/registry.h"
+#include "net/base/net_util.h"
+#include "net/base/network_change_notifier.h"
+#include "net/dns/dns_config_service_win.h"
+#include "net/dns/file_path_watcher_wrapper.h"
+
+namespace net {
+namespace internal {
+
+namespace {
+
+// Watches a single registry key for changes.
+class RegistryWatcher : public base::win::ObjectWatcher::Delegate,
+                        public base::NonThreadSafe {
+ public:
+  typedef base::Callback<void(bool succeeded)> CallbackType;
+  RegistryWatcher() {}
+
+  bool Watch(const wchar_t* key, const CallbackType& callback) {
+    DCHECK(CalledOnValidThread());
+    DCHECK(!callback.is_null());
+    DCHECK(callback_.is_null());
+    callback_ = callback;
+    if (key_.Open(HKEY_LOCAL_MACHINE, key, KEY_NOTIFY) != ERROR_SUCCESS)
+      return false;
+    if (key_.StartWatching() != ERROR_SUCCESS)
+      return false;
+    if (!watcher_.StartWatching(key_.watch_event(), this))
+      return false;
+    return true;
+  }
+
+  virtual void OnObjectSignaled(HANDLE object) OVERRIDE {
+    DCHECK(CalledOnValidThread());
+    bool succeeded = (key_.StartWatching() == ERROR_SUCCESS) &&
+                      watcher_.StartWatching(key_.watch_event(), this);
+    if (!succeeded) {
+      if (key_.Valid()) {
+        watcher_.StopWatching();
+        key_.StopWatching();
+        key_.Close();
+      }
+    }
+    if (!callback_.is_null())
+      callback_.Run(succeeded);
+  }
+
+ private:
+  CallbackType callback_;
+  base::win::RegKey key_;
+  base::win::ObjectWatcher watcher_;
+
+  DISALLOW_COPY_AND_ASSIGN(RegistryWatcher);
+};
+
+}  // namespace
+
+// Watches registry for changes. Setting up watches requires IO loop.
+class DnsConfigWatcher::Core {
+ public:
+  Core() {}
+  ~Core() {}
+
+  bool Watch() {
+    RegistryWatcher::CallbackType callback =
+        base::Bind(&Core::OnRegistryChanged, base::Unretained(this));
+
+    bool success = true;
+
+    // The Tcpip key must be present.
+    if (!tcpip_watcher_.Watch(kTcpipPath, callback)) {
+      LOG(ERROR) << "DNS registry watch failed to start.";
+      success = false;
+    }
+
+    // Watch for IPv6 nameservers.
+    tcpip6_watcher_.Watch(kTcpip6Path, callback);
+
+    // DNS suffix search list and devolution can be configured via group
+    // policy which sets this registry key. If the key is missing, the policy
+    // does not apply, and the DNS client uses Tcpip and Dnscache settings.
+    // If a policy is installed, DnsConfigService will need to be restarted.
+    // BUG=99509
+
+    dnscache_watcher_.Watch(kDnscachePath, callback);
+    policy_watcher_.Watch(kPolicyPath, callback);
+
+    if (!hosts_watcher_.Watch(GetHostsPath(),
+                              base::Bind(&Core::OnHostsChanged,
+                                         base::Unretained(this)))) {
+      LOG(ERROR) << "DNS hosts watch failed to start.";
+      success = false;
+    }
+    return success;
+  }
+
+ private:
+  void OnRegistryChanged(bool succeeded) {
+    if (succeeded) {
+      NetworkChangeNotifier::NotifyObserversOfDNSChange(
+          NetworkChangeNotifier::CHANGE_DNS_SETTINGS);
+    } else {
+      LOG(ERROR) << "DNS config watch failed.";
+      NetworkChangeNotifier::NotifyObserversOfDNSChange(
+          NetworkChangeNotifier::CHANGE_DNS_WATCH_FAILED);
+    }
+  }
+
+  void OnHostsChanged(bool succeeded) {
+    if (succeeded) {
+      NetworkChangeNotifier::NotifyObserversOfDNSChange(
+          NetworkChangeNotifier::CHANGE_DNS_HOSTS);
+    } else {
+      LOG(ERROR) << "DNS hosts watch failed.";
+      NetworkChangeNotifier::NotifyObserversOfDNSChange(
+          NetworkChangeNotifier::CHANGE_DNS_WATCH_FAILED);
+    }
+  }
+
+  RegistryWatcher tcpip_watcher_;
+  RegistryWatcher tcpip6_watcher_;
+  RegistryWatcher dnscache_watcher_;
+  RegistryWatcher policy_watcher_;
+  FilePathWatcherWrapper hosts_watcher_;
+
+  DISALLOW_COPY_AND_ASSIGN(Core);
+};
+
+DnsConfigWatcher::DnsConfigWatcher() {}
+
+DnsConfigWatcher::~DnsConfigWatcher() {}
+
+void DnsConfigWatcher::Init() {
+  core_.reset(new Core());
+  if (core_->Watch()) {
+    NetworkChangeNotifier::NotifyObserversOfDNSChange(
+        NetworkChangeNotifier::CHANGE_DNS_WATCH_STARTED);
+  }
+  // TODO(szym): re-start watcher if that makes sense. http://crbug.com/116139
+}
+
+void DnsConfigWatcher::CleanUp() {
+  core_.reset();
+}
+
+}  // namespace internal
+}  // namespace net
+