void *silc_packet_wait_init(SilcPacketStream stream,
                                const SilcID *source_id, ...);

    Initializes a packet waiter for the packet stream `stream' and
    for the variable argument list of packet types.  The function
    silc_packet_wait can be used to block the thread until a packet
    has been received.

    This function is used to initialize the waiting and to give the list
    of packet types that caller wish to receive.  The variable argument
    list must end with -1.  To receive all packets use SILC_PACKET_ANY.
    If the `source_id' is non-NULL then only packets of the specified
    type from the specified `source_id' are received.  If it is NULL
    then the packet source is ignored.

    Returns a context that must be given to the silc_packet_wait function
    as argument.  Returns NULL on error.  To uninitialize the waiting
    call silc_packet_wait_uninit.

    Note that packets may be available immediately after calling this
    function and they will be buffered, until silc_packet_wait is called.

    void *waiter;

    // Will wait for private message packets
    waiter = silc_packet_wait_init(stream, NULL,
                                   SILC_PACKET_PRIVATE_MESSAGE, -1);