void silc_socket_host_lookup(SilcSocketConnection sock,
                                 bool port_lookup,
                                 SilcSocketHostLookupCb callback,
                                 void *context,
                                 SilcSchedule schedule);

    Performs asynchronous host name and IP address lookups for the
    specified socket connection. This may be called when the socket
    connection is created and the full IP address and fully qualified
    domain name information is desired. The `callback' with `context'
    will be called after the lookup is performed. The `schedule'
    is the application's scheduler which the lookup routine needs.
    If the socket connection is freed during the lookup the library
    will automatically cancel the lookup and the `callback' will not be
    called.

    If `port_lookup' is TRUE then the remote port of the socket
    connection is resolved. After the information is resolved they
    are accessible using sock->ip and sock->hostname pointers. Note
    that if the both IP and FQDN could not be resolved the sock->hostname
    includes the IP address of the remote host. The resolved port is
    available in sock->port.