Offline state detection for linux, using new D-Bus library.

net/base/network_change_notifier_linux.cc

 // Copyright (c) 2011 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/base/network_change_notifier_linux.h"
 
 #include <errno.h>
 #include <sys/socket.h>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/callback.h"
 #include "base/compiler_specific.h"
 #include "base/eintr_wrapper.h"
 #include "base/file_util.h"
 #include "base/files/file_path_watcher.h"
 #include "base/memory/weak_ptr.h"
+#include "base/synchronization/lock.h"
+#include "base/synchronization/waitable_event.h"
+#include "base/threading/platform_thread.h"
 #include "base/threading/thread.h"
+#include "dbus/bus.h"
+#include "dbus/message.h"
+#include "dbus/object_proxy.h"
 #include "net/base/net_errors.h"
 #include "net/base/network_change_notifier_netlink_linux.h"
 
 using ::base::files::FilePathWatcher;
 
 namespace net {
 
 namespace {
 
 const int kInvalidSocket = -1;
 
+const char kNetworkManagerServiceName[] = "org.freedesktop.NetworkManager";
+const char kNetworkManagerPath[] = "/org/freedesktop/NetworkManager";
+const char kNetworkManagerInterface[] = "org.freedesktop.NetworkManager";
+
+// http://projects.gnome.org/NetworkManager/developers/spec-08.html#type-NM_STATE
+enum {
+  NM_LEGACY_STATE_UNKNOWN = 0,
+  NM_LEGACY_STATE_ASLEEP = 1,
+  NM_LEGACY_STATE_CONNECTING = 2,
+  NM_LEGACY_STATE_CONNECTED = 3,
+  NM_LEGACY_STATE_DISCONNECTED = 4
+};
+
+// http://projects.gnome.org/NetworkManager/developers/migrating-to-09/spec.html#type-NM_STATE
+enum {
+  NM_STATE_UNKNOWN = 0,
+  NM_STATE_ASLEEP = 10,
+  NM_STATE_DISCONNECTED = 20,
+  NM_STATE_DISCONNECTING = 30,
+  NM_STATE_CONNECTING = 40,
+  NM_STATE_CONNECTED_LOCAL = 50,
+  NM_STATE_CONNECTED_SITE = 60,
+  NM_STATE_CONNECTED_GLOBAL = 70
+};
+
+// A wrapper around NetworkManager's D-Bus API.
+class NetworkManagerApi {
+ public:
+  explicit NetworkManagerApi(const base::Closure& notification_callback)
+      : is_offline_(false),
+        offline_state_initialized_(true /*manual_reset*/, false),
+        notification_callback_(notification_callback),
+        helper_thread_id_(base::kInvalidThreadId),
+        ALLOW_THIS_IN_INITIALIZER_LIST(ptr_factory_(this)) { }
+
+  // For testing.
+  NetworkManagerApi(const base::Closure& notification_callback, dbus::Bus* bus)
+      : is_offline_(false),
+        offline_state_initialized_(true /*manual_reset*/, false),
+        notification_callback_(notification_callback),
+        helper_thread_id_(base::kInvalidThreadId),
+        ALLOW_THIS_IN_INITIALIZER_LIST(ptr_factory_(this)),
+        system_bus_(bus) { }
+
+  ~NetworkManagerApi() { }
+
+  // Should be called on a helper thread which must be of type IO.
+  void Init();
+
+  // Must be called by the helper thread's CleanUp() method.
+  void CleanUp();
+
+  // Implementation of NetworkChangeNotifierLinux::IsCurrentlyOffline().
+  // Safe to call from any thread, but will block until Init() has completed.
+  bool IsCurrentlyOffline();
+
+ private:
+  // Callbacks for D-Bus API.
+  void OnStateChanged(dbus::Message* message);

[satorux1, 2011/10/26 17:37:09]

We usually have a blank line between functions.

[adamk, 2011/10/26 18:35:52]

Done.

+  void OnResponse(dbus::Response* response) {
+    OnStateChanged(response);
+    offline_state_initialized_.Signal();
+  }
+  void OnSignaled(dbus::Signal* signal) {
+    OnStateChanged(signal);
+  }
+  void OnConnected(const std::string&, const std::string&, bool success) {
+    DLOG_IF(WARNING, !success) << "Failed to set up offline state detection";
+  }
+
+  // Converts a NetworkManager state uint to a bool.
+  static bool StateIsOffline(uint32 state);
+
+  bool is_offline_;
+  base::Lock is_offline_lock_;
+  base::WaitableEvent offline_state_initialized_;
+
+  base::Closure notification_callback_;
+
+  base::PlatformThreadId helper_thread_id_;
+
+  base::WeakPtrFactory<NetworkManagerApi> ptr_factory_;
+
+  scoped_refptr<dbus::Bus> system_bus_;
+
+  DISALLOW_COPY_AND_ASSIGN(NetworkManagerApi);
+};
+
+void NetworkManagerApi::Init() {
+  // D-Bus requires an IO MessageLoop.
+  DCHECK_EQ(MessageLoop::current()->type(), MessageLoop::TYPE_IO);
+  helper_thread_id_ = base::PlatformThread::CurrentId();
+
+  if (!system_bus_) {
+    dbus::Bus::Options options;
+    options.bus_type = dbus::Bus::SYSTEM;
+    options.connection_type = dbus::Bus::PRIVATE;
+    system_bus_ = new dbus::Bus(options);
+  }
+
+  dbus::ObjectProxy* proxy =
+      system_bus_->GetObjectProxy(kNetworkManagerServiceName,
+                                  kNetworkManagerPath);
+
+  // Get the initial state asynchronously.
+  dbus::MethodCall method_call(DBUS_INTERFACE_PROPERTIES, "Get");
+  dbus::MessageWriter builder(&method_call);
+  builder.AppendString(kNetworkManagerInterface);
+  builder.AppendString("State");
+  proxy->CallMethod(
+      &method_call, dbus::ObjectProxy::TIMEOUT_USE_DEFAULT,
+      base::Bind(&NetworkManagerApi::OnResponse, ptr_factory_.GetWeakPtr()));
+
+  // And sign up for notifications.
+  proxy->ConnectToSignal(
+      kNetworkManagerInterface,
+      "StateChanged",
+      base::Bind(&NetworkManagerApi::OnSignaled, ptr_factory_.GetWeakPtr()),
+      base::Bind(&NetworkManagerApi::OnConnected, ptr_factory_.GetWeakPtr()));
+}
+
+void NetworkManagerApi::CleanUp() {
+  DCHECK_EQ(helper_thread_id_, base::PlatformThread::CurrentId());
+  ptr_factory_.InvalidateWeakPtrs();
+}
+
+void NetworkManagerApi::OnStateChanged(dbus::Message* message) {
+  DCHECK_EQ(helper_thread_id_, base::PlatformThread::CurrentId());
+  if (!message) {
+    DLOG(WARNING) << "No response received for initial state request";
+    return;
+  }
+  dbus::MessageReader reader(message);
+  uint32 state = 0;
+  if (!reader.HasMoreData() || !reader.PopUint32(&state)) {
+    DLOG(WARNING) << "Unexpected response for NetworkManager State request: "
+                  << message->ToString();
+    return;
+  }
+  bool new_is_offline = StateIsOffline(state);
+  {
+    base::AutoLock lock(is_offline_lock_);
+    if (is_offline_ != new_is_offline)
+      is_offline_ = new_is_offline;
+    else
+      return;
+  }
+  if (offline_state_initialized_.IsSignaled())
+    notification_callback_.Run();
+}
+
+bool NetworkManagerApi::StateIsOffline(uint32 state) {
+  switch (state) {
+    case NM_LEGACY_STATE_CONNECTED:
+    case NM_STATE_CONNECTED_SITE:
+    case NM_STATE_CONNECTED_GLOBAL:
+      // Definitely connected
+      return false;
+    case NM_LEGACY_STATE_DISCONNECTED:
+    case NM_STATE_DISCONNECTED:
+      // Definitely disconnected
+      return true;
+    case NM_STATE_CONNECTED_LOCAL:
+      // Local networking only; I'm treating this as offline (keybuk)
+      return true;
+    case NM_LEGACY_STATE_CONNECTING:
+    case NM_STATE_DISCONNECTING:
+    case NM_STATE_CONNECTING:
+      // In-flight change to connection status currently underway
+      return true;
+    case NM_LEGACY_STATE_ASLEEP:
+    case NM_STATE_ASLEEP:
+      // Networking disabled or no devices on system
+      return true;
+    default:
+      // Unknown status
+      return false;
+  }
+}
+
+bool NetworkManagerApi::IsCurrentlyOffline() {
+  offline_state_initialized_.Wait();
+  base::AutoLock lock(is_offline_lock_);
+  return is_offline_;
+}
+
 class DNSWatchDelegate : public FilePathWatcher::Delegate {
  public:
   explicit DNSWatchDelegate(const base::Closure& callback)
       : callback_(callback) {}
   virtual ~DNSWatchDelegate() {}
   // FilePathWatcher::Delegate interface
   virtual void OnFilePathChanged(const FilePath& path) OVERRIDE;
   virtual void OnFilePathError(const FilePath& path) OVERRIDE;
  private:
   base::Closure callback_;
   DISALLOW_COPY_AND_ASSIGN(DNSWatchDelegate);
 };
 
 void DNSWatchDelegate::OnFilePathChanged(const FilePath& path) {
   // Calls NetworkChangeNotifier::NotifyObserversOfDNSChange().
   callback_.Run();
 }
 
 void DNSWatchDelegate::OnFilePathError(const FilePath& path) {
   LOG(ERROR) << "DNSWatchDelegate::OnFilePathError for " << path.value();
 }
 
 }  // namespace
 
 class NetworkChangeNotifierLinux::Thread
     : public base::Thread, public MessageLoopForIO::Watcher {
  public:
   Thread();
+  explicit Thread(dbus::Bus* bus);

[satorux1, 2011/10/26 17:37:09]

Function overloading is prohibited per our C++ style guide. Here, I think you
can get rid of Thread().

[adamk, 2011/10/26 18:35:52]

Done, and got rid of the extra constructor on NetworkManagerApi.

   virtual ~Thread();
 
   // MessageLoopForIO::Watcher:
   virtual void OnFileCanReadWithoutBlocking(int fd);
   virtual void OnFileCanWriteWithoutBlocking(int /* fd */);
 
+  // Plumbing for NetworkChangeNotifier::IsCurrentlyOffline.
+  // Safe to call from any thread.
+  bool IsCurrentlyOffline() {
+    return network_manager_api_.IsCurrentlyOffline();
+  }
+
  protected:
   // base::Thread
   virtual void Init();
   virtual void CleanUp();
 
  private:
   void NotifyObserversOfIPAddressChange() {
     NetworkChangeNotifier::NotifyObserversOfIPAddressChange();
   }
 
   void NotifyObserversOfDNSChange() {
     NetworkChangeNotifier::NotifyObserversOfDNSChange();
   }
 
+  static void NotifyObserversOfOnlineStateChange() {
+    NetworkChangeNotifier::NotifyObserversOfOnlineStateChange();
+  }
+
   // Starts listening for netlink messages.  Also handles the messages if there
   // are any available on the netlink socket.
   void ListenForNotifications();
 
   // Attempts to read from the netlink socket into |buf| of length |len|.
   // Returns the bytes read on synchronous success and ERR_IO_PENDING if the
   // recv() would block.  Otherwise, it returns a net error code.
   int ReadNotificationMessage(char* buf, size_t len);
 
   // The netlink socket descriptor.
   int netlink_fd_;
   MessageLoopForIO::FileDescriptorWatcher netlink_watcher_;
 
   // Technically only needed for ChromeOS, but it's ugly to #ifdef out.
   base::WeakPtrFactory<Thread> ptr_factory_;
 
   // Used to watch for changes to /etc/resolv.conf and /etc/hosts.
   scoped_ptr<base::files::FilePathWatcher> resolv_file_watcher_;
   scoped_ptr<base::files::FilePathWatcher> hosts_file_watcher_;
   scoped_refptr<DNSWatchDelegate> file_watcher_delegate_;
 
+  // Used to detect online/offline state changes.
+  NetworkManagerApi network_manager_api_;
+
   DISALLOW_COPY_AND_ASSIGN(Thread);
 };
 
 NetworkChangeNotifierLinux::Thread::Thread()
     : base::Thread("NetworkChangeNotifier"),
       netlink_fd_(kInvalidSocket),
-      ALLOW_THIS_IN_INITIALIZER_LIST(ptr_factory_(this)) {
+      ALLOW_THIS_IN_INITIALIZER_LIST(ptr_factory_(this)),
+      network_manager_api_(
+          base::Bind(&NetworkChangeNotifierLinux::Thread
+                     ::NotifyObserversOfOnlineStateChange)) {
+}
+
+NetworkChangeNotifierLinux::Thread::Thread(dbus::Bus* bus)
+    : base::Thread("NetworkChangeNotifier"),
+      netlink_fd_(kInvalidSocket),
+      ALLOW_THIS_IN_INITIALIZER_LIST(ptr_factory_(this)),
+      network_manager_api_(
+          base::Bind(&NetworkChangeNotifierLinux::Thread
+                     ::NotifyObserversOfOnlineStateChange),
+          bus) {
 }
 
 NetworkChangeNotifierLinux::Thread::~Thread() {}
 
 void NetworkChangeNotifierLinux::Thread::Init() {
   resolv_file_watcher_.reset(new FilePathWatcher);
   hosts_file_watcher_.reset(new FilePathWatcher);
   file_watcher_delegate_ = new DNSWatchDelegate(base::Bind(
       &NetworkChangeNotifierLinux::Thread::NotifyObserversOfDNSChange,
       base::Unretained(this)));

[satorux1, 2011/10/26 17:37:09]

For base::Unretained(this) to be safe, |this| needs to outlive the callback.
Could you add some comment about it's safe here?

[adamk, 2011/10/26 18:35:52]

This code didn't change in this patch.  But I've made it static to match my
notification method, and avoided passing |this| altogether.

   if (!resolv_file_watcher_->Watch(
           FilePath(FILE_PATH_LITERAL("/etc/resolv.conf")),
           file_watcher_delegate_.get())) {
     LOG(ERROR) << "Failed to setup watch for /etc/resolv.conf";
   }
   if (!hosts_file_watcher_->Watch(FilePath(FILE_PATH_LITERAL("/etc/hosts")),
           file_watcher_delegate_.get())) {
     LOG(ERROR) << "Failed to setup watch for /etc/hosts";
   }
   netlink_fd_ = InitializeNetlinkSocket();
   if (netlink_fd_ < 0) {
     netlink_fd_ = kInvalidSocket;
     return;
   }
   ListenForNotifications();
+
+  network_manager_api_.Init();
 }
 
 void NetworkChangeNotifierLinux::Thread::CleanUp() {
   if (netlink_fd_ != kInvalidSocket) {
     if (HANDLE_EINTR(close(netlink_fd_)) != 0)
       PLOG(ERROR) << "Failed to close socket";
     netlink_fd_ = kInvalidSocket;
     netlink_watcher_.StopWatchingFileDescriptor();
   }
   // Kill watchers early to make sure they won't try to call
   // into us via the delegate during destruction.
   resolv_file_watcher_.reset();
   hosts_file_watcher_.reset();
+
+  network_manager_api_.CleanUp();
 }
 
 void NetworkChangeNotifierLinux::Thread::OnFileCanReadWithoutBlocking(int fd) {
   DCHECK_EQ(fd, netlink_fd_);
   ListenForNotifications();
 }
 
 void NetworkChangeNotifierLinux::Thread::OnFileCanWriteWithoutBlocking(
     int /* fd */) {
   NOTREACHED();
@@ skipping 52 matching lines @@
 
 NetworkChangeNotifierLinux::NetworkChangeNotifierLinux()
     : notifier_thread_(new Thread) {
   // We create this notifier thread because the notification implementation
   // needs a MessageLoopForIO, and there's no guarantee that
   // MessageLoop::current() meets that criterion.
   base::Thread::Options thread_options(MessageLoop::TYPE_IO, 0);
   notifier_thread_->StartWithOptions(thread_options);
 }
 
+// Used only for testing, injects a dbus::Bus into the helper thread.
+NetworkChangeNotifierLinux::NetworkChangeNotifierLinux(dbus::Bus* bus)
+    : notifier_thread_(new Thread(bus)) {
+  base::Thread::Options thread_options(MessageLoop::TYPE_IO, 0);
+  notifier_thread_->StartWithOptions(thread_options);
+}
+
 NetworkChangeNotifierLinux::~NetworkChangeNotifierLinux() {
   // We don't need to explicitly Stop(), but doing so allows us to sanity-
   // check that the notifier thread shut down properly.
   notifier_thread_->Stop();
 }
 
 bool NetworkChangeNotifierLinux::IsCurrentlyOffline() const {
-  // TODO(eroman): http://crbug.com/53473
-  return false;
+  return notifier_thread_->IsCurrentlyOffline();
 }
 
 }  // namespace net