266 lines
7.6 KiB
Python
266 lines
7.6 KiB
Python
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"""Frame objects that do the frame demarshaling and marshaling."""
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import logging
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import struct
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from pika import amqp_object
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from pika import exceptions
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from pika import spec
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from pika.compat import byte
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LOGGER = logging.getLogger(__name__)
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class Frame(amqp_object.AMQPObject):
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"""Base Frame object mapping. Defines a behavior for all child classes for
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assignment of core attributes and implementation of the a core _marshal
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method which child classes use to create the binary AMQP frame.
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"""
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NAME = 'Frame'
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def __init__(self, frame_type, channel_number):
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"""Create a new instance of a frame
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:param int frame_type: The frame type
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:param int channel_number: The channel number for the frame
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"""
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self.frame_type = frame_type
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self.channel_number = channel_number
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def _marshal(self, pieces):
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"""Create the full AMQP wire protocol frame data representation
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:rtype: bytes
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"""
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payload = b''.join(pieces)
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return struct.pack('>BHI', self.frame_type, self.channel_number,
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len(payload)) + payload + byte(spec.FRAME_END)
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def marshal(self):
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"""To be ended by child classes
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:raises NotImplementedError
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"""
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raise NotImplementedError
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class Method(Frame):
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"""Base Method frame object mapping. AMQP method frames are mapped on top
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of this class for creating or accessing their data and attributes.
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"""
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NAME = 'METHOD'
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def __init__(self, channel_number, method):
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"""Create a new instance of a frame
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:param int channel_number: The frame type
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:param pika.Spec.Class.Method method: The AMQP Class.Method
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"""
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Frame.__init__(self, spec.FRAME_METHOD, channel_number)
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self.method = method
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def marshal(self):
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"""Return the AMQP binary encoded value of the frame
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:rtype: str
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"""
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pieces = self.method.encode()
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pieces.insert(0, struct.pack('>I', self.method.INDEX))
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return self._marshal(pieces)
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class Header(Frame):
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"""Header frame object mapping. AMQP content header frames are mapped
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on top of this class for creating or accessing their data and attributes.
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"""
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NAME = 'Header'
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def __init__(self, channel_number, body_size, props):
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"""Create a new instance of a AMQP ContentHeader object
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:param int channel_number: The channel number for the frame
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:param int body_size: The number of bytes for the body
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:param pika.spec.BasicProperties props: Basic.Properties object
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"""
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Frame.__init__(self, spec.FRAME_HEADER, channel_number)
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self.body_size = body_size
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self.properties = props
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def marshal(self):
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"""Return the AMQP binary encoded value of the frame
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:rtype: str
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"""
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pieces = self.properties.encode()
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pieces.insert(0, struct.pack('>HxxQ', self.properties.INDEX,
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self.body_size))
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return self._marshal(pieces)
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class Body(Frame):
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"""Body frame object mapping class. AMQP content body frames are mapped on
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to this base class for getting/setting of attributes/data.
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"""
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NAME = 'Body'
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def __init__(self, channel_number, fragment):
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"""
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Parameters:
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- channel_number: int
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- fragment: unicode or str
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"""
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Frame.__init__(self, spec.FRAME_BODY, channel_number)
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self.fragment = fragment
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def marshal(self):
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"""Return the AMQP binary encoded value of the frame
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:rtype: str
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"""
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return self._marshal([self.fragment])
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class Heartbeat(Frame):
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"""Heartbeat frame object mapping class. AMQP Heartbeat frames are mapped
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on to this class for a common access structure to the attributes/data
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values.
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"""
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NAME = 'Heartbeat'
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def __init__(self):
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"""Create a new instance of the Heartbeat frame"""
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Frame.__init__(self, spec.FRAME_HEARTBEAT, 0)
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def marshal(self):
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"""Return the AMQP binary encoded value of the frame
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:rtype: str
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"""
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return self._marshal(list())
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class ProtocolHeader(amqp_object.AMQPObject):
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"""AMQP Protocol header frame class which provides a pythonic interface
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for creating AMQP Protocol headers
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"""
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NAME = 'ProtocolHeader'
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def __init__(self, major=None, minor=None, revision=None):
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"""Construct a Protocol Header frame object for the specified AMQP
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version
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:param int major: Major version number
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:param int minor: Minor version number
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:param int revision: Revision
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"""
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self.frame_type = -1
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self.major = major or spec.PROTOCOL_VERSION[0]
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self.minor = minor or spec.PROTOCOL_VERSION[1]
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self.revision = revision or spec.PROTOCOL_VERSION[2]
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def marshal(self):
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"""Return the full AMQP wire protocol frame data representation of the
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ProtocolHeader frame
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:rtype: str
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"""
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return b'AMQP' + struct.pack('BBBB', 0, self.major, self.minor,
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self.revision)
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def decode_frame(data_in):
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"""Receives raw socket data and attempts to turn it into a frame.
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Returns bytes used to make the frame and the frame
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:param str data_in: The raw data stream
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:rtype: tuple(bytes consumed, frame)
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:raises: pika.exceptions.InvalidFrameError
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"""
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# Look to see if it's a protocol header frame
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try:
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if data_in[0:4] == b'AMQP':
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major, minor, revision = struct.unpack_from('BBB', data_in, 5)
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return 8, ProtocolHeader(major, minor, revision)
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except (IndexError, struct.error):
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return 0, None
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# Get the Frame Type, Channel Number and Frame Size
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try:
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(frame_type, channel_number,
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frame_size) = struct.unpack('>BHL', data_in[0:7])
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except struct.error:
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return 0, None
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# Get the frame data
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frame_end = spec.FRAME_HEADER_SIZE + frame_size + spec.FRAME_END_SIZE
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# We don't have all of the frame yet
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if frame_end > len(data_in):
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return 0, None
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# The Frame termination chr is wrong
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if data_in[frame_end - 1:frame_end] != byte(spec.FRAME_END):
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raise exceptions.InvalidFrameError("Invalid FRAME_END marker")
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# Get the raw frame data
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frame_data = data_in[spec.FRAME_HEADER_SIZE:frame_end - 1]
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if frame_type == spec.FRAME_METHOD:
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# Get the Method ID from the frame data
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method_id = struct.unpack_from('>I', frame_data)[0]
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# Get a Method object for this method_id
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method = spec.methods[method_id]()
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# Decode the content
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method.decode(frame_data, 4)
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# Return the amount of data consumed and the Method object
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return frame_end, Method(channel_number, method)
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elif frame_type == spec.FRAME_HEADER:
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# Return the header class and body size
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class_id, weight, body_size = struct.unpack_from('>HHQ', frame_data)
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# Get the Properties type
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properties = spec.props[class_id]()
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# Decode the properties
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out = properties.decode(frame_data[12:])
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# Return a Header frame
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return frame_end, Header(channel_number, body_size, properties)
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elif frame_type == spec.FRAME_BODY:
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# Return the amount of data consumed and the Body frame w/ data
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return frame_end, Body(channel_number, frame_data)
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elif frame_type == spec.FRAME_HEARTBEAT:
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# Return the amount of data and a Heartbeat frame
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return frame_end, Heartbeat()
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raise exceptions.InvalidFrameError("Unknown frame type: %i" % frame_type)
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