cNetwork: Added an OnError callback for listening servers.

The callback receives the error details.

src/OSSupport/Network.cpp

@@ -841,6 +841,10 @@ cServerHandleImplPtr cServerHandleImpl::Listen(
 	{
 		cNetworkSingleton::Get().AddServer(res);
 	}
+	else
+	{
+		a_ListenCallbacks->OnError(res->m_ErrorCode, res->m_ErrorMsg);
+	}
 	return res;
 }
 
@@ -1062,6 +1066,7 @@ cTCPLink::cTCPLink(cCallbacksPtr a_Callbacks):
 
 
 
+
 ////////////////////////////////////////////////////////////////////////////////
 // cNetworkSingleton:
 

src/OSSupport/Network.h

@@ -139,6 +139,9 @@ public:
 		/** Called when the TCP server created with Listen() accepts an incoming connection.
 		Provides the newly created Link that can be used for communication. */
 		virtual void OnAccepted(cTCPLink & a_Link) = 0;
+
+		/** Called when the socket fails to listen on the specified port. */
+		virtual void OnError(int a_ErrorCode, const AString & a_ErrorMsg) = 0;
 	};
 	typedef SharedPtr<cListenCallbacks> cListenCallbacksPtr;