[net/dns] Isolate DnsConfigWatcher from DnsConfigService.

net/dns/dns_config_watcher_posix.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 <string>
+
+#include "base/basictypes.h"
+#include "base/bind.h"
+#include "base/callback.h"
+#include "base/file_path.h"
+#include "base/logging.h"
+#include "base/memory/scoped_ptr.h"
+#include "net/base/network_change_notifier.h"
+#include "net/dns/file_path_watcher_wrapper.h"
+
+#if defined(OS_MACOSX)
+#include "net/dns/notify_watcher_mac.h"
+#endif
+
+namespace net {
+namespace internal {
+
+namespace {
+
+const FilePath::CharType* kFilePathHosts = FILE_PATH_LITERAL("/etc/hosts");
+
+#if defined(OS_MACOSX)
+// From 10.7.3 configd-395.10/dnsinfo/dnsinfo.h
+static const char* kDnsNotifyKey =
+    "com.apple.system.SystemConfiguration.dns_configuration";
+
+class ConfigWatcher {
+ public:
+  bool Watch(const base::Callback<void(bool succeeded)>& callback) {
+    return watcher_.Watch(kDnsNotifyKey, callback);
+  }
+ private:
+  NotifyWatcherMac watcher_;
+};
+#else
+
+#ifndef _PATH_RESCONF  // Normally defined in <resolv.h>
+#define _PATH_RESCONF "/etc/resolv.conf"
+#endif
+
+static const FilePath::CharType* kFilePathConfig =
+    FILE_PATH_LITERAL(_PATH_RESCONF);
+
+class ConfigWatcher {
+ public:
+  bool Watch(const base::Callback<void(bool succeeded)>& callback) {
+    return watcher_.Watch(FilePath(kFilePathConfig), callback);
+  }
+ private:
+  FilePathWatcherWrapper watcher_;
+};
+#endif
+
+}  // namespace
+
+class DnsConfigWatcher::Core {
+ public:
+  Core() {}
+  ~Core() {}
+
+  bool Watch() {
+    bool success = true;
+    if (!config_watcher_.Watch(base::Bind(&Core::OnConfigChanged,
+                                          base::Unretained(this)))) {
+      LOG(ERROR) << "DNS config watch failed to start.";
+      success = false;
+    }
+    if (!hosts_watcher_.Watch(FilePath(kFilePathHosts),
+                              base::Bind(&Core::OnHostsChanged,
+                                         base::Unretained(this)))) {
+      LOG(ERROR) << "DNS hosts watch failed to start.";
+      success = false;
+    }
+    return success;
+  }
+
+ private:
+  void OnConfigChanged(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);
+    }
+  }
+
+  ConfigWatcher config_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