1 files changed, 43 insertions, 8 deletions

diff --git a/cast/streaming/environment.h b/cast/streaming/environment.h
index 0ab9a399..606f408f 100644
--- a/cast/streaming/environment.h
+++ b/cast/streaming/environment.h
@@ -33,6 +33,36 @@ class Environment : public UdpSocket::Client {
     virtual ~PacketConsumer();
   };
 
+  // Consumers of the environment's UDP socket should be careful to check the
+  // socket's state before accessing its methods, especially
+  // GetBoundLocalEndpoint(). If the environment is |kStarting|, the
+  // local endpoint may not be set yet and will be zero initialized.
+  enum class SocketState {
+    // Socket is still initializing. Usually the UDP socket bind is
+    // the last piece.
+    kStarting,
+
+    // The socket is ready for use and has been bound.
+    kReady,
+
+    // The socket is either closed (normally or due to an error) or in an
+    // invalid state. Currently the environment does not create a new socket
+    // in this case, so to be used again the environment itself needs to be
+    // recreated.
+    kInvalid
+  };
+
+  // Classes concerned with the Environment's UDP socket state may inherit from
+  // |Subscriber| and then |Subscribe|.
+  class SocketSubscriber {
+   public:
+    // Event that occurs when the environment is ready for use.
+    virtual void OnSocketReady() = 0;
+
+    // Event that occurs when the environment has experienced a fatal error.
+    virtual void OnSocketInvalid(Error error) = 0;
+  };
+
   // Construct with the given clock source and TaskRunner. Creates and
   // internally-owns a UdpSocket, and immediately binds it to the given
   // |local_endpoint|. If embedders do not care what interface/address the UDP
@@ -54,12 +84,6 @@ class Environment : public UdpSocket::Client {
   // is a bound socket.
   virtual IPEndpoint GetBoundLocalEndpoint() const;
 
-  // Set a handler function to run whenever non-recoverable socket errors occur.
-  // If never set, the default is to emit log messages at error priority.
-  void set_socket_error_handler(std::function<void(Error)> handler) {
-    socket_error_handler_ = handler;
-  }
-
   // Get/Set the remote endpoint. This is separate from the constructor because
   // the remote endpoint is, in some cases, discovered only after receiving a
   // packet.
@@ -68,6 +92,15 @@ class Environment : public UdpSocket::Client {
     remote_endpoint_ = endpoint;
   }
 
+  // Returns the current state of the UDP socket. This method is virtual
+  // to allow tests to simulate socket state.
+  SocketState socket_state() const { return state_; }
+  void set_socket_state_for_testing(SocketState state) { state_ = state; }
+
+  // Subscribe to socket changes. Callers can unsubscribe by passing
+  // nullptr.
+  void SetSocketSubscriber(SocketSubscriber* subscriber);
+
   // Start/Resume delivery of incoming packets to the given |packet_consumer|.
   // Delivery will continue until DropIncomingPackets() is called.
   void ConsumeIncomingPackets(PacketConsumer* packet_consumer);
@@ -97,20 +130,22 @@ class Environment : public UdpSocket::Client {
 
  private:
   // UdpSocket::Client implementation.
+  void OnBound(UdpSocket* socket) final;
   void OnError(UdpSocket* socket, Error error) final;
   void OnSendError(UdpSocket* socket, Error error) final;
   void OnRead(UdpSocket* socket, ErrorOr<UdpPacket> packet_or_error) final;
 
-
   // The UDP socket bound to the local endpoint that was passed into the
   // constructor, or null if socket creation failed.
   const std::unique_ptr<UdpSocket> socket_;
 
   // These are externally set/cleared. Behaviors are described in getter/setter
   // method comments above.
-  std::function<void(Error)> socket_error_handler_;
+  IPEndpoint local_endpoint_{};
   IPEndpoint remote_endpoint_{};
   PacketConsumer* packet_consumer_ = nullptr;
+  SocketState state_ = SocketState::kStarting;
+  SocketSubscriber* socket_subscriber_ = nullptr;
 };
 
 }  // namespace cast