Re: UDP Send gets NETWORK_IS_UNREACHABLE

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On 2018-07-03 12:43, Petter Fryklund wrote:

> We have a need to send a broadcast message. In the test environment on Windows everything is fine. But in the productional environment on Linux we receive Socket Error NETWORK_IS_UNREACHABLE. I have searched the net a bit and it seems like we should use so_bindtodev, but that is not available on GNAT. Does anybody have some advice?

You do not need so_bindtodev, that is for sure.

You could do something like this:

    Create_Socket (Socket, Family_Inet, Socket_Datagram);
    Set_Socket_Option
    (  Socket,
       Socket_Level,
       (Reuse_Address, True)
    );
    Set_Socket_Option
    (  Socket,
       Socket_Level,
       (Broadcast, True)
    );
    Set_Socket_Option
    (  Socket,
       Socket_Level,
       (Receive_Timeout, <some reasonable value if responses expected>)
    );
    Address.Addr := Addresses (Get_Host_By_Name (<my host name>), 1);
    Address.Port := <port>;
    Bind_Socket (Socket, Address);
    Address.Addr := Broadcast_Inet_Addr;
    Address.Port := <port>;
    Send_Socket (Socket, <announce>, Last, Address'Access);
    loop -- Gathering responses
       begin
          Receive_Socket (Socket, <response>, Last, <who is there>);
       exception
         when Socket_Error =>
            null;
       end;
    end loop;

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de