FreeOpcUa / python-opcua

            = struct.unpack("<5I", data.read(20))

        return ack

class AsymmetricAlgorithmHeader(uatypes.FrozenClass):

    def __init__(self):

        self.SecurityPolicyURI = "http://opcfoundation.org/UA/SecurityPolicy#None"

        self.SenderCertificate = None

        self.ReceiverCertificateThumbPrint = None

        self._freeze = True

    def to_binary(self):

        b = []

        b.append(uatypes.pack_string(self.SecurityPolicyURI))

        b.append(uatypes.pack_string(self.SenderCertificate))

        b.append(uatypes.pack_string(self.ReceiverCertificateThumbPrint))

        return b"".join(b)

    @staticmethod

    def from_binary(data):

        hdr = AsymmetricAlgorithmHeader()

        hdr.SecurityPolicyURI = uatypes.unpack_string(data)

        hdr.SenderCertificate = uatypes.unpack_bytes(data)

        hdr.ReceiverCertificateThumbPrint = uatypes.unpack_bytes(data)

        return hdr

    def __str__(self):

        return "{}(SecurityPolicy:{}, certificatesize:{}, receiverCertificatesize:{} )".format(

            self.__class__.__name__, self.SecurityPolicyURI, len(self.SenderCertificate),

            len(self.ReceiverCertificateThumbPrint))

    __repr__ = __str__

            self.MessageType, self.ChunkType, self.body_size, self.ChannelId)

    __repr__ = __str__

class ErrorMessage(uatypes.FrozenClass):

    def __init__(self):

        self.Error = uatypes.StatusCode()

        self.Reason = ""

        self._freeze = True

    def to_binary(self):

        b = []

        b.append(self.Error.to_binary())

        b.append(uatypes.pack_string(self.Reason))

        return b"".join(b)

    @staticmethod

    def from_binary(data):

        ack = ErrorMessage()

        ack.Error = uatypes.StatusCode.from_binary(data)

        ack.Reason = uatypes.unpack_string(data)

        return ack

    def __str__(self):

        return "MessageAbort(error:{}, reason:{})".format(self.Error, self.Reason)

    __repr__ = __str__