Question

I am able to get the port returned, but the IP is not. Should I be using something else other than getsockname? thx

        if ((sock = ::socket(AF_INET, SOCK_STREAM, 0)) == -1) {
            c.Format("Socket Error:  %d", GetLastError());
            tcpMESSAGE = 1;
            break;
        }


        server_addr.sin_family = AF_INET;         
        server_addr.sin_port = htons(4000); //port setting    
        server_addr.sin_addr.s_addr = INADDR_ANY; 

        if (::bind(sock, (struct sockaddr *)&server_addr, sizeof(struct sockaddr)) == -1) {
            c.Format("Bind Error:  %d", GetLastError());
            tcpMESSAGE = 1;
            break;
        }

        if(1==1){
            int len = sizeof server_addr;
            if(::getsockname(sock,(struct sockaddr*)&server_addr,&len) == -1)
                MessageBox("Error local host ip");

            c.Format("local addr %s:%u\n  errno: %d",inet_ntoa(server_addr.sin_addr),ntohs(server_addr.sin_port), errno);
            MessageBox(c);
        }

Answer 1

You are binding to INADDR_ANY, but you have not connected the socket to a peer yet, so there is no IP for getsockname() to return. After a connection has been established via connect() or accept(), then getsockname() can return the specific IP that is being used for that connection. Binding alone is not enough, unless you bind to a specific IP, which you are not doing.