def header_from_binary(data):
hdr = ua.Header()
hdr.MessageType, hdr.ChunkType, hdr.packet_size = struct.unpack("<3scI", data.read(8))
hdr.body_size = hdr.packet_size - 8
if hdr.MessageType in (ua.MessageType.SecureOpen, ua.MessageType.SecureClose, ua.MessageType.SecureMessage):
hdr.body_size -= 4
hdr.ChannelId = Primitives.UInt32.unpack(data)
hdr.header_size = 12
return hdr
def uatcp_to_binary(message_type, message):
"""
Convert OPC UA TCP message (see OPC UA specs Part 6, 7.1) to binary.
The only supported types are Hello, Acknowledge and ErrorMessage
"""
header = ua.Header(message_type, ua.ChunkType.Single)
binmsg = struct_to_binary(message)
header.body_size = len(binmsg)
return header_to_binary(header) + binmsg
def __init__(self, security_policy, body=b'', msg_type=ua.MessageType.SecureMessage, chunk_type=ua.ChunkType.Single):
self.MessageHeader = ua.Header(msg_type, chunk_type)
if msg_type in (ua.MessageType.SecureMessage, ua.MessageType.SecureClose):
self.SecurityHeader = ua.SymmetricAlgorithmHeader()
elif msg_type == ua.MessageType.SecureOpen:
self.SecurityHeader = ua.AsymmetricAlgorithmHeader()
else:
raise ua.UaError("Unsupported message type: {0}".format(msg_type))
self.SequenceHeader = ua.SequenceHeader()
self.Body = body
self.security_policy = security_policy
