Question

I’m fairly new to C programming and having some difficulties wrapping my brain around the usage of GSocket to send UDP messages.

The application I’m working on is extremely simple. I have GTK_ENTRY fields where the user can enter an IP address, port, and a message, and when they click a button it should send the message via UDP to the address and port specified.

This is my function so far:

static void send_message()
{
    GInetAddress *udpAddress;
    GSocketAddress *udpSocketAddress;
    GSocket *udpSocket;

    udpAddress = g_inet_address_new_from_string(gtk_entry_get_text (GTK_ENTRY (ipField)));
    guint16 udpPort = atoi(gtk_entry_get_text (GTK_ENTRY (portField)));

    udpSocketAddress = g_inet_socket_address_new(udpAddress, udpPort);

    udpSocket = g_socket_new(G_SOCKET_FAMILY_IPV4, G_SOCKET_TYPE_DATAGRAM, 17, NULL);

    const gchar *myMessage = gtk_entry_get_text (GTK_ENTRY (mainShowCommandField));
    g_socket_send (udpSocket, myMessage, sizeof(myMessage), NULL, NULL);
}

The program compiles without errors, but when I trigger the function, the message is not being sent.

I’m sure I’m missing something stupid, but any help would be greatly appreciated!!

Answer 1

You forgot to connect the socket. Do

g_socket_connect(udpSocket, udpSocketAddress, NULL, NULL);

Before calling g_socket_send. You also might want to add error checking to your code.