bool silc_packet_assemble(SilcPacketContext *packet, SilcRng rng,
                              SilcCipher cipher, SilcHmac hmac,
                              SilcSocketConnection sock,
                              const unsigned char *data, SilcUInt32 data_len,
                              const SilcBuffer assembled_packet);

    Assembles new packet to be ready for encrypting and sending out.
    The `packet' is filled by caller to include the packet header specific
    values.  This prepares the socket connection's `sock' outoing buffer
    for sending data, and returns the assembled packet to the 
    `assembled_packet' pointer sent by the caller.  The `assembled_packet'
    is a reference to the socket connection's outgoing buffer.  The
    returned packet can be encrypted, and then sent to network by calling
    silc_packet_send function.  The `assembled_packet' may be freely
    modified (like encrypted etc.) but it must not be freed, since it is
    reference from `sock' outgoing buffer, and it is const.