socket is created in disconnected state. socket can't be created in open state because shared_ptr methods aren't available to doRead until after class has been constructed and the socket is dependent on ioservice running.

libp2p/UDP.h

@@ -57,17 +57,17 @@ struct UDPSocketEvents
 	
 /**
  * @brief UDP Interface
- * Handler must implement UDPSocketEvents. S is maximum data size (bytes) of UDP datagram.
+ * Handler must implement UDPSocketEvents.
  */
-template <typename Handler, unsigned S>
-class UDPSocket: UDPSocketFace, public std::enable_shared_from_this<UDPSocket<Handler, S>>
+template <typename Handler, unsigned MaxDatagramSize>
+class UDPSocket: UDPSocketFace, public std::enable_shared_from_this<UDPSocket<Handler, MaxDatagramSize>>
 {
 public:
-	static constexpr unsigned datagramSize = S;
-	static_assert(datagramSize < 65507, "UDP datagrams cannot be larger than 65507 bytes");
+	static constexpr unsigned maxDatagramSize = MaxDatagramSize;
+	static_assert(maxDatagramSize < 65507, "UDP datagrams cannot be larger than 65507 bytes");
 	
 	/// Construct open socket to endpoint.
-	UDPSocket(ba::io_service& _io, UDPSocketEvents& _host, unsigned _port): m_host(_host), m_socket(_io, bi::udp::endpoint(bi::udp::v4(), _port)) { m_started.store(false); m_closed.store(true); };
+	UDPSocket(ba::io_service& _io, UDPSocketEvents& _host, unsigned _port): m_host(_host), m_endpoint(bi::udp::v4(), _port), m_socket(_io) { m_started.store(false); m_closed.store(true); };
 	virtual ~UDPSocket() { disconnect(); }
 
 	/// Socket will begin listening for and delivering packets
@@ -76,6 +76,9 @@ public:
 		bool expect = false;
 		if (!m_started.compare_exchange_strong(expect, true))
 			return;
+		
+		m_socket.open(bi::udp::v4());
+		m_socket.bind(m_endpoint);
 
 		m_closed = false;
 		doRead();
@@ -83,7 +86,7 @@ public:
 
 	void send(UDPDatagram const& _datagram)
 	{
-		if (!m_started)
+		if (m_closed)
 			return;
 		
 		Guard l(x_sendQ);
@@ -91,13 +94,15 @@ public:
 		if (sendQ.size() == 1 && !m_closed.load())
 			doWrite();
 	}
+	
+	bool isOpen() { return !m_closed; }
 
 	void disconnect() { disconnectWithError(boost::asio::error::connection_reset); }
 	
 protected:
 	void doRead()
 	{
-		auto self(UDPSocket<Handler, S>::shared_from_this());
+		auto self(UDPSocket<Handler, MaxDatagramSize>::shared_from_this());
 		m_socket.async_receive_from(boost::asio::buffer(recvData), recvEndpoint, [this, self](boost::system::error_code _ec, size_t _len)
 		{
 			if (_ec)
@@ -113,7 +118,7 @@ protected:
 	void doWrite()
 	{
 		const UDPDatagram& datagram = sendQ[0];
-		auto self(UDPSocket<Handler, S>::shared_from_this());
+		auto self(UDPSocket<Handler, MaxDatagramSize>::shared_from_this());
 		m_socket.async_send_to(boost::asio::buffer(datagram.data), datagram.to, [this, self](boost::system::error_code _ec, std::size_t)
 		{
 			if (_ec)
@@ -132,7 +137,7 @@ protected:
 	void disconnectWithError(boost::system::error_code _ec)
 	{
 		// If !started and already stopped, shutdown has already occured. (EOF or Operation canceled)
-		if (!m_started && m_closed)
+		if (!m_started && m_closed && !m_socket.is_open())
 			return;
 
 		assert(_ec);
@@ -146,8 +151,8 @@ protected:
 		// TODO: (if non-zero error) schedule high-priority writes
 
 		// prevent concurrent disconnect
-		bool yes = true;
-		if (!m_started.compare_exchange_strong(yes, false))
+		bool expected = true;
+		if (!m_started.compare_exchange_strong(expected, false))
 			return;
 		
 		// set m_closed to true to prevent undeliverable egress messages
@@ -170,10 +175,11 @@ protected:
 	std::atomic<bool> m_started;		///< Atomically ensure connection is started once. Start cannot occur unless m_started is false. Managed by start and disconnectWithError.
 	
 	UDPSocketEvents& m_host;					///< Interface which owns this socket.
+	bi::udp::endpoint m_endpoint;			///< Endpoint which we listen to.
 	
 	Mutex x_sendQ;
 	std::deque<UDPDatagram> sendQ;
-	std::array<byte, datagramSize> recvData;		///< Buffer for ingress datagrams.
+	std::array<byte, maxDatagramSize> recvData;		///< Buffer for ingress datagrams.
 	bi::udp::endpoint recvEndpoint;			///< Endpoint data was received from.
 	bi::udp::socket m_socket;