void silc_ske_set_callbacks(SilcSKE ske,
                                SilcSKESendPacketCb send_packet,
                                SilcSKECb payload_receive,
                                SilcSKEVerifyCb verify_key,
                                SilcSKECb proto_continue,
                                SilcSKECheckVersion check_version,
                                void *context);

    Sets the callback functions for the SKE session.

    The `send_packet' callback is a function that sends the packet to
    network. The SKE library will call it at any time packet needs to
    be sent to the remote host.

    The `payload_receive' callback is called when the remote host's Key
    Exchange Start Payload has been processed.  The payload is saved
    to ske->start_payload if the application would need it.  The application
    must also provide the payload to the next state of the SKE.

    The `verify_key' callback is called to verify the received public key
    or certificate.  The verification process is most likely asynchronous.
    That is why the application must call the completion callback when the
    verification process has been completed. The library then calls the user
    callback (`proto_continue'), if it is provided to indicate that the SKE
    protocol may continue. If this SKE session context is used to perform
    rekey, this callback usually is not provided as argument since sending
    public key in rekey is not mandatory. Setting this callback implies
    that remote end MUST send its public key, and this could cause
    problems when performing rekey. When doing normal SKE session this
    callback should be set.

    The `proto_continue' callback is called to indicate that it is
    safe to continue the execution of the SKE protocol after executing
    an asynchronous operation, such as calling the `verify_key' callback
    function, which is asynchronous. The application should check the
    ske->status in this function to check whether it is Ok to continue
    the execution of the protocol.

    The `check_version' callback is called to verify the remote host's
    version. The application may check its own version against the remote
    host's version and determine whether supporting the remote host
    is possible.

    The `context' is passed as argument to all of the above callback
    functions.