better handshake error logging, esp when remote disconnects

libp2p/RLPxHandshake.cpp

@@ -131,7 +131,14 @@ void RLPXHandshake::readAck()
 
 void RLPXHandshake::error()
 {
-	clog(NetConnect) << "Disconnecting " << m_socket->remoteEndpoint() << " (Handshake Failed)";
+	m_idleTimer.cancel();
+	
+	auto connected = m_socket->isConnected();
+	if (connected && !m_socket->remoteEndpoint().address().is_unspecified())
+		clog(NetConnect) << "Disconnecting " << m_socket->remoteEndpoint() << " (Handshake Failed)";
+	else
+		clog(NetConnect) << "Handshake Failed (Connection reset by peer)";
+
 	m_socket->close();
 	if (m_io != nullptr)
 		delete m_io;
@@ -140,7 +147,10 @@ void RLPXHandshake::error()
 void RLPXHandshake::transition(boost::system::error_code _ech)
 {
 	if (_ech || m_nextState == Error || m_cancel)
+	{
+		clog(NetConnect) << "Handshake Failed (I/O Error:" << _ech.message() << ")";
 		return error();
+	}
 	
 	auto self(shared_from_this());
 	if (m_nextState == New)
@@ -265,7 +275,8 @@ void RLPXHandshake::transition(boost::system::error_code _ech)
 	{
 		if (!_ec)
 		{
-			clog(NetWarn) << "Disconnecting " << m_socket->remoteEndpoint() << " (Handshake Timeout)";
+			if (!m_socket->remoteEndpoint().address().is_unspecified())
+				clog(NetWarn) << "Disconnecting " << m_socket->remoteEndpoint() << " (Handshake Timeout)";
 			cancel();
 		}
 	});