Question

I have created a socket using the following lines of code and i get a valid socket and connection is established between the client and server machines. Is there a possibility that the socket becomes invalid due to network disturbances or any other reason.

If so how do we check whether the socket is valid or not.

    SOCKET SocServer; 

    //To Set up the sockaddr structure 
    ServerSock.sin_family = AF_INET; 
    ServerSock.sin_addr.s_addr = INADDR_ANY     
    ServerSock.sin_port = htons(PortNumber);//port number of 5005 

    // To Create a socket for listening on PortNumber 
    if(( SocServer = socket( AF_INET, SOCK_STREAM, 0 )) == INVALID_SOCKET ) 
    { 
        return FALSE; 
    } 

    //To bind the socket with wPortNumber 
    if(bind(SocServer,(sockaddr*)&ServerSock,sizeof(ServerSock))!=0) 
    { 
        return FALSE; 
    } 

    // To Listen for the connection on wPortNumber 
    if(listen(SocServer,SOMAXCONN)!=0) 
    { 
        return FALSE; 
    }

I know i can check for INVALID_SOCKET which in other words means the socket is 0. Is there any other way out because my SocServer will have a value say 2500, i want to check if this socket is valid.

Answer 1

Pass your socket to any one of the windows socket functions (eg. getsockopt()), if the socket is invalid, it will return SOCKET_ERROR while WSAGetLastError() will return WSAENOTSOCK.

It is important to note that INVALID_SOCKET does not equal 0(the actual value, which you should not use specifically is ((SOCKET)(~0))