int
    silc_net_udp_receive(SilcStream stream, char *remote_ip_addr,
                         SilcUInt32 remote_ip_addr_size, int *remote_port,
                         unsigned char *ret_data, SilcUInt32 data_size)

    Receive a UDP packet from the `stream'.  The IP address and port of
    the sender is returned into `remote_ip_addr' buffer and `remote_port'
    pointer.  The packet data is returned into the `ret_data' buffer.

    Returns the length of the packet, or -1 on error or 0 in case of EOF.