GenericTLV.get_size() - Code Metrics - Inspection of "[minor] Fix Scrutinizer coverage" - kytos/python-openflow - Measure and Improve Code Quality continuously with Scrutinizer

Passed

Pull Request — master (#425)

by Carlos Eduardo

created 2017-07-25 19:22 UTC

GenericTLV.get_size() A

↳ Parent: GenericTLV

Complexity

Conditions

Size

Total Lines

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	1
CRAP Score	3.6875

Importance

Changes	1
Bugs	0	Features	0

Metric	Value
c	1
b	0
f	0
dl	0
loc	10
ccs	1
cts	4
cp	0.25
rs	9.4285
cc	2
crap	3.6875

"""Basic Network packet types.

Defines and Implements Basic Network packet types , such as Ethertnet and LLDP.
"""

from pyof.foundation.base import GenericStruct
from pyof.foundation.basic_types import (
    BinaryData, HWAddress, IPAddress, UBInt8, UBInt16)
from pyof.foundation.exceptions import PackException

__all__ = ('Ethernet', 'GenericTLV', 'IPv4', 'TLVWithSubType', 'LLDP')


class Ethernet(GenericStruct):
    """Ethernet "struct".

    Objects of this class represents an ethernet packet. It contains the
    'Ethernet header', composed by destination (MAC), source (MAC), type
    (EtherType)[1] and the payload of the packet, as binary data.

    This class does not consider the Ethernet 'Preamble' or the 'CRC'.

    There is also a get_hash method, that hashes the binary representation of
    the object so we can have a unique representation of the ethernet packet,
    so we can keep a track of ethernet packets being flooded over the network.

    [1] EtherTypes:
    http://www.iana.org/assignments/ieee-802-numbers/ieee-802-numbers.xhtml#ieee-802-numbers-1
    """

    destination = HWAddress()
    source = HWAddress()
    ether_type = UBInt16()
    data = BinaryData()

    def __init__(self, destination=None, source=None, ether_type=None,
                 data=b''):
        """Create an instance and set its attributes.

        Args:
            destination (:class:`~pyof.foundation.basic_types.HWAddress`):
                The final destination MAC address.
            source (:class:`~pyof.foundation.basic_types.HWAddress`):
                The source Mac address of the packet.
            ether_type (:class:`~pyof.foundation.basic_types.UBInt16`):
                The EtherType of packet.
            data (:class:`~pyof.foundation.basic_types.BinaryData`):
                The content of the packet in binary format.
        """
        super().__init__()
        self.destination = destination
        self.source = source
        self.ether_type = ether_type
        self.data = data

    def get_hash(self):
        """Calculate a hash and returns it.

        Returns:
            int: Integer value that identifies this instance.
        """
        return hash(self.pack())


class GenericTLV(GenericStruct):
    """TLV structure of LLDP packets.

    This is a Type, Length and Value (TLV) struct.

    The LLDP/TLV definition states that the Type field have 7 bits, while
    the length have 9 bits. The Value must be between 0-511 octets.

    Internally, on the instances of this class, the Type is a integer
    (0-127) and the Length is dynamically calculated based on the current
    type and value.
    """

    def __init__(self, tlv_type=127, value=BinaryData()):
        """Create an instance and set its attributes.

        Args:
            tlv_type (int): Type used by this class. Defaults to 127.
            value (:class:`~pyof.foundation.basic_types.BinaryData`):
                Value stored by GenericTLV.
        """
        super().__init__()
        self.tlv_type = tlv_type
        self._value = value

    @property
    def value(self):
        """Return the value stored by GenericTLV.

        Returns:
            :class:`~pyof.foundation.basic_types.BinaryData`:
                Value stored by GenericTLV.
        """
        return self._value

    @property
    def length(self):
        """Return the length of value stored by GenericTLV.

        Returns:
            int: Value length in bytes.
        """
        return len(self.value.pack())

    @property
    def header(self):
        """Header of the TLV Packet.

        The header is composed by the Type (7 bits) and Length (9 bits),
        summing up 16 bits. To achieve that, we need to do some bitshift
        operations.

        Returns:
            :class:`~pyof.foundation.basic_types.UBInt16`:
                Result after all operations.
        """
        return UBInt16(((self.tlv_type & 127) << 9) | (self.length & 511))

    def pack(self, value=None):
        """Pack the TLV in a binary representation.

        Returns:
            bytes: Binary representation of the struct object.

        Raises:
            :exc:`~.exceptions.ValidationError`: If validation fails.
        """
        if value is None:
            output = self.header.pack()
            output += self.value.pack()
            return output

        elif isinstance(value, type(self)):
            return value.pack()
        else:
            msg = "{} is not an instance of {}".format(value,
                                                       type(self).__name__)
            raise PackException(msg)

    def unpack(self, buffer, offset=0):
        """Unpack a binary message into this object's attributes.

        Unpack the binary value *buff* and update this object attributes based
        on the results.

        Args:
            buff (bytes): Binary data package to be unpacked.
            offset (int): Where to begin unpacking.

        Raises:
            Exception: If there is a struct unpacking error.
        """
        header = UBInt16()
        header.unpack(buffer[offset:offset+2])
        self.tlv_type = header.value >> 9
        length = header.value & 511
        begin, end = offset + 2, offset + 2 + length
        self._value = BinaryData(buffer[begin:end])

    def get_size(self, value=None):
        """Return struct size.

        Returns:
            int: Returns the struct size based on inner attributes.
        """
        if isinstance(value, type(self)):
            return value.get_size()

        return 2 + self.length


class IPv4(GenericStruct):
    """IPv4 packet "struct".

    Contains all fields of an IP version 4 packet header, plus the upper layer
    content as binary data.
    Some of the fields were merged together because of their size being
    inferior to 8 bits. They are represented as a single class attribute, but
    pack/unpack methods will take into account the values in individual
    instance attributes.
    """

    #: _version_ihl (:class:`UBInt8`): IP protocol version + Internet Header
    #: Length (words)
    _version_ihl = UBInt8()
    #: _dscp_ecn (:class:`UBInt8`): Differentiated Services Code Point
    #: (ToS - Type of Service) + Explicit Congestion Notification
    _dscp_ecn = UBInt8()
    #: length (:class:`UBInt16`): IP packet length (bytes)
    length = UBInt16()
    #: identification (:class:`UBInt16`): Packet ID - common to all fragments
    identification = UBInt16()
    #: _flags_offset (:class:`UBInt16`): Fragmentation flags + fragmentation
    #: offset
    _flags_offset = UBInt16()
    #: ttl (:class:`UBInt8`): Packet time-to-live
    ttl = UBInt8()
    #: protocol (:class:`UBInt8`): Upper layer protocol number
    protocol = UBInt8()
    #: checksum (:class:`UBInt16`): Header checksum
    checksum = UBInt16()
    #: source (:class:`IPAddress`): Source IPv4 address
    source = IPAddress()
    #: destination (:class:`IPAddress`): Destination IPv4 address
    destination = IPAddress()
    #: options (:class:`BinaryData`): IP Options - up to 320 bits, always
    #: padded to 32 bits
    options = BinaryData()
    #: data (:class:`BinaryData`): Packet data
    data = BinaryData()

    def __init__(self, version=4, ihl=5, dscp=0, ecn=0, length=0, # noqa
                 identification=0, flags=0, offset=0, ttl=255, protocol=0,
                 checksum=0, source="0.0.0.0", destination="0.0.0.0",
                 options=b'', data=b''):
        """The contructor receives the parameters below.

        Args:
            version (int): IP protocol version. Defaults to 4.
            ihl (int): Internet Header Length. Default is 5.
            dscp (int): Differentiated Service Code Point. Defaults to 0.
            ecn (int): Explicit Congestion Notification. Defaults to 0.
            length (int): IP packet length in bytes. Defaults to 0.
            identification (int): Packet Id. Defaults to 0.
            flags (int): IPv4 Flags. Defults 0.
            offset (int): IPv4 offset. Defaults to 0.
            ttl (int): Packet time-to-live. Defaults to 255
            protocol (int): Upper layer protocol number. Defaults to 0.
            checksum (int): Header checksum. Defaults to 0.
            source (str): Source IPv4 address. Defaults to "0.0.0.0"
            destination (str): Destination IPv4 address. Defaults to "0.0.0.0"
            options (bytes): IP options. Defaults to empty bytes.
            data (bytes): Packet data. Defaults to empty bytes.
        """
        super().__init__()
        self.version = version
        self.ihl = ihl
        self.dscp = dscp
        self.ecn = ecn
        self.length = length
        self.identification = identification
        self.flags = flags
        self.offset = offset
        self.ttl = ttl
        self.protocol = protocol
        self.checksum = checksum
        self.source = source
        self.destination = destination
        self.options = options
        self.data = data

    def _update_checksum(self):
        """Update the packet checksum to enable integrity check."""
        source_list = [int(octet) for octet in self.source.split(".")]
        destination_list = [int(octet) for octet in
                            self.destination.split(".")]
        source_upper = (source_list[0] << 8) + source_list[1]
        source_lower = (source_list[2] << 8) + source_list[3]
        destination_upper = (destination_list[0] << 8) + destination_list[1]
        destination_lower = (destination_list[2] << 8) + destination_list[3]

        block_sum = ((self._version_ihl << 8 | self._dscp_ecn) + self.length +
                     self.identification + self._flags_offset +
                     (self.ttl << 8 | self.protocol) + source_upper +
                     source_lower + destination_upper + destination_lower)

        while block_sum > 65535:
            carry = block_sum >> 16
            block_sum = (block_sum & 65535) + carry

        self.checksum = ~block_sum & 65535

    def pack(self, value=None):
        """Pack the struct in a binary representation.

        Merge some fields to ensure correct packing.

        Returns:
            bytes: Binary representation of this instance.
        """
        # Set the correct IHL based on options size
        if self.options:
            self.ihl += int(len(self.options) / 4)

        # Set the correct packet length based on header length and data
        self.length = int(self.ihl * 4 + len(self.data))

        self._version_ihl = self.version << 4 | self.ihl
        self._dscp_ecn = self.dscp << 2 | self.ecn
        self._flags_offset = self.flags << 13 | self.offset

        # Set the checksum field before packing
        self._update_checksum()

        return super().pack()

    def unpack(self, buff, offset=0):
        """Unpack a binary struct into this object's attributes.

        Return the values instead of the lib's basic types.

        Args:
            buff (bytes): Binary buffer.
            offset (int): Where to begin unpacking.

        Raises:
            :exc:`~.exceptions.UnpackException`: If unpack fails.
        """
        super().unpack(buff, offset)

        self.version = self._version_ihl.value >> 4
        self.ihl = self._version_ihl.value & 15
        self.dscp = self._dscp_ecn.value >> 2
        self.ecn = self._dscp_ecn.value & 3
        self.length = self.length.value
        self.identification = self.identification.value
        self.flags = self._flags_offset.value >> 13
        self.offset = self._flags_offset.value & 8191
        self.ttl = self.ttl.value
        self.protocol = self.protocol.value
        self.checksum = self.checksum.value
        self.source = self.source.value
        self.destination = self.destination.value

        if self.ihl > 5:
            options_size = (self.ihl - 5) * 4
            self.data = self.options.value[options_size:]
            self.options = self.options.value[:options_size]
        else:
            self.data = self.options.value
            self.options = b''


class TLVWithSubType(GenericTLV):
    """Modify the :class:`GenericTLV` to a Organization Specific TLV structure.

    Beyond the standard TLV (type, length, value), we can also have a more
    specific structure, with the :attr:`value` field being splitted into a
    :attr:`sub_type` field and a new :attr:`sub_value` field.
    """

    def __init__(self, tlv_type=1, sub_type=7, sub_value=BinaryData()):
        """Create an instance and set its attributes.

        Args:
            tlv_type (int): Type used by this class. Defaults to 1.
            sub_type (int): Sub type value used by this class. Defaults to 7.
            sub_value (:class:`~pyof.foundation.basic_types.BinaryData`):
                Data stored by TLVWithSubType. Defaults to empty BinaryData.
        """
        super().__init__(tlv_type)
        self.sub_type = sub_type
        self.sub_value = sub_value

    @property
    def value(self):
        """Return sub type and sub value as binary data.

        Returns:
            :class:`~pyof.foundation.basic_types.BinaryData`:
                BinaryData calculated.
        """
        binary = UBInt8(self.sub_type).pack() + self.sub_value.pack()
        return BinaryData(binary)

    def unpack(self, buffer, offset=0):
        """Unpack a binary message into this object's attributes.

        Unpack the binary value *buff* and update this object attributes based
        on the results.

        Args:
            buff (bytes): Binary data package to be unpacked.
            offset (int): Where to begin unpacking.

        Raises:
            Exception: If there is a struct unpacking error.
        """
        header = UBInt16()
        header.unpack(buffer[offset:offset+2])
        self.tlv_type = header.value >> 9
        length = header.value & 511
        begin, end = offset + 2, offset + 2 + length
        sub_type = UBInt8()
        sub_type.unpack(buffer[begin:begin+1])
        self.sub_type = sub_type.value
        self.sub_value = BinaryData(buffer[begin+1:end])


class LLDP(GenericStruct):
    """LLDP class.

    Build a LLDP packet with TLVSubtype and Generic Subtypes.

    It contains a chassis_id TLV, a port_id TLV, a TTL (Time to live) and
    another TLV to represent the end of the LLDP Packet.
    """

    #: chassis_id (:class:`~TLVWithSubType`) with tlv_type = 1 and sub_type = 7
    chassis_id = TLVWithSubType(tlv_type=1, sub_type=7)
    #: port_id (:class:`TLVWithSubType`) with tlv = 2 and sub_type = 7
    port_id = TLVWithSubType(tlv_type=2, sub_type=7)
    #: TTL (:class:`GenericTLV`) time is given in seconds, between 0 and 65535,
    #: with tlv_type = 3
    ttl = GenericTLV(tlv_type=3, value=UBInt16(120))
    # We are not using list of tlvs for now
    # tlvs = ListOfTLVs()
    #: end (:class:`GenericTLV`) with tlv_type = 0
    end = GenericTLV(tlv_type=0)


1		"""Basic Network packet types.
2
3		Defines and Implements Basic Network packet types , such as Ethertnet and LLDP.
4		"""
5
6	1	from pyof.foundation.base import GenericStruct
7	1	from pyof.foundation.basic_types import (
8		BinaryData, HWAddress, IPAddress, UBInt8, UBInt16)
9	1	from pyof.foundation.exceptions import PackException
10
11	1	__all__ = ('Ethernet', 'GenericTLV', 'IPv4', 'TLVWithSubType', 'LLDP')
12
13
14	1	class Ethernet(GenericStruct):
15		"""Ethernet "struct".
16
17		Objects of this class represents an ethernet packet. It contains the
18		'Ethernet header', composed by destination (MAC), source (MAC), type
19		(EtherType)[1] and the payload of the packet, as binary data.
20
21		This class does not consider the Ethernet 'Preamble' or the 'CRC'.
22
23		There is also a get_hash method, that hashes the binary representation of
24		the object so we can have a unique representation of the ethernet packet,
25		so we can keep a track of ethernet packets being flooded over the network.
26
27		[1] EtherTypes:
28		http://www.iana.org/assignments/ieee-802-numbers/ieee-802-numbers.xhtml#ieee-802-numbers-1
29		"""
30
31	1	destination = HWAddress()
32	1	source = HWAddress()
33	1	ether_type = UBInt16()
34	1	data = BinaryData()
35
36	1	def __init__(self, destination=None, source=None, ether_type=None,
37		data=b''):
38		"""Create an instance and set its attributes.
39
40		Args:
41		destination (:class:`~pyof.foundation.basic_types.HWAddress`):
42		The final destination MAC address.
43		source (:class:`~pyof.foundation.basic_types.HWAddress`):
44		The source Mac address of the packet.
45		ether_type (:class:`~pyof.foundation.basic_types.UBInt16`):
46		The EtherType of packet.
47		data (:class:`~pyof.foundation.basic_types.BinaryData`):
48		The content of the packet in binary format.
49		"""
50		super().__init__()
51		self.destination = destination
52		self.source = source
53		self.ether_type = ether_type
54		self.data = data
55
56	1	def get_hash(self):
57		"""Calculate a hash and returns it.
58
59		Returns:
60		int: Integer value that identifies this instance.
61		"""
62		return hash(self.pack())
63
64
65	1	class GenericTLV(GenericStruct):
66		"""TLV structure of LLDP packets.
67
68		This is a Type, Length and Value (TLV) struct.
69
70		The LLDP/TLV definition states that the Type field have 7 bits, while
71		the length have 9 bits. The Value must be between 0-511 octets.
72
73		Internally, on the instances of this class, the Type is a integer
74		(0-127) and the Length is dynamically calculated based on the current
75		type and value.
76		"""
77
78	1	def __init__(self, tlv_type=127, value=BinaryData()):
79		"""Create an instance and set its attributes.
80
81		Args:
82		tlv_type (int): Type used by this class. Defaults to 127.
83		value (:class:`~pyof.foundation.basic_types.BinaryData`):
84		Value stored by GenericTLV.
85		"""
86	1	super().__init__()
87	1	self.tlv_type = tlv_type
88	1	self._value = value
89
90	1	@property
91		def value(self):
92		"""Return the value stored by GenericTLV.
93
94		Returns:
95		:class:`~pyof.foundation.basic_types.BinaryData`:
96		Value stored by GenericTLV.
97		"""
98	1	return self._value
99
100	1	@property
101		def length(self):
102		"""Return the length of value stored by GenericTLV.
103
104		Returns:
105		int: Value length in bytes.
106		"""
107	1	return len(self.value.pack())
108
109	1	@property
110		def header(self):
111		"""Header of the TLV Packet.
112
113		The header is composed by the Type (7 bits) and Length (9 bits),
114		summing up 16 bits. To achieve that, we need to do some bitshift
115		operations.
116
117		Returns:
118		:class:`~pyof.foundation.basic_types.UBInt16`:
119		Result after all operations.
120		"""
121	1	return UBInt16(((self.tlv_type & 127) << 9) \| (self.length & 511))
122
123	1	def pack(self, value=None):
124		"""Pack the TLV in a binary representation.
125
126		Returns:
127		bytes: Binary representation of the struct object.
128
129		Raises:
130		:exc:`~.exceptions.ValidationError`: If validation fails.
131		"""
132	1	if value is None:
133	1	output = self.header.pack()
134	1	output += self.value.pack()
135	1	return output
136
137		elif isinstance(value, type(self)):
138		return value.pack()
139		else:
140		msg = "{} is not an instance of {}".format(value,
141		type(self).__name__)
142		raise PackException(msg)
143
144	1	def unpack(self, buffer, offset=0):
145		"""Unpack a binary message into this object's attributes.
146
147		Unpack the binary value buff and update this object attributes based
148		on the results.
149
150		Args:
151		buff (bytes): Binary data package to be unpacked.
152		offset (int): Where to begin unpacking.
153
154		Raises:
155		Exception: If there is a struct unpacking error.
156		"""
157	1	header = UBInt16()
158	1	header.unpack(buffer[offset:offset+2])
159	1	self.tlv_type = header.value >> 9
160	1	length = header.value & 511
161	1	begin, end = offset + 2, offset + 2 + length
162	1	self._value = BinaryData(buffer[begin:end])
163
164	1	def get_size(self, value=None):
165		"""Return struct size.
166
167		Returns:
168		int: Returns the struct size based on inner attributes.
169		"""
170		if isinstance(value, type(self)):
171		return value.get_size()
172
173		return 2 + self.length
174
175
176	1	class IPv4(GenericStruct):
177		"""IPv4 packet "struct".
178
179		Contains all fields of an IP version 4 packet header, plus the upper layer
180		content as binary data.
181		Some of the fields were merged together because of their size being
182		inferior to 8 bits. They are represented as a single class attribute, but
183		pack/unpack methods will take into account the values in individual
184		instance attributes.
185		"""
186
187		#: _version_ihl (:class:`UBInt8`): IP protocol version + Internet Header
188		#: Length (words)
189	1	_version_ihl = UBInt8()
190		#: _dscp_ecn (:class:`UBInt8`): Differentiated Services Code Point
191		#: (ToS - Type of Service) + Explicit Congestion Notification
192	1	_dscp_ecn = UBInt8()
193		#: length (:class:`UBInt16`): IP packet length (bytes)
194	1	length = UBInt16()
195		#: identification (:class:`UBInt16`): Packet ID - common to all fragments
196	1	identification = UBInt16()
197		#: _flags_offset (:class:`UBInt16`): Fragmentation flags + fragmentation
198		#: offset
199	1	_flags_offset = UBInt16()
200		#: ttl (:class:`UBInt8`): Packet time-to-live
201	1	ttl = UBInt8()
202		#: protocol (:class:`UBInt8`): Upper layer protocol number
203	1	protocol = UBInt8()
204		#: checksum (:class:`UBInt16`): Header checksum
205	1	checksum = UBInt16()
206		#: source (:class:`IPAddress`): Source IPv4 address
207	1	source = IPAddress()
208		#: destination (:class:`IPAddress`): Destination IPv4 address
209	1	destination = IPAddress()
210		#: options (:class:`BinaryData`): IP Options - up to 320 bits, always
211		#: padded to 32 bits
212	1	options = BinaryData()
213		#: data (:class:`BinaryData`): Packet data
214	1	data = BinaryData()
215
216	1	def __init__(self, version=4, ihl=5, dscp=0, ecn=0, length=0, # noqa
217		identification=0, flags=0, offset=0, ttl=255, protocol=0,
218		checksum=0, source="0.0.0.0", destination="0.0.0.0",
219		options=b'', data=b''):
220		"""The contructor receives the parameters below.
221
222		Args:
223		version (int): IP protocol version. Defaults to 4.
224		ihl (int): Internet Header Length. Default is 5.
225		dscp (int): Differentiated Service Code Point. Defaults to 0.
226		ecn (int): Explicit Congestion Notification. Defaults to 0.
227		length (int): IP packet length in bytes. Defaults to 0.
228		identification (int): Packet Id. Defaults to 0.
229		flags (int): IPv4 Flags. Defults 0.
230		offset (int): IPv4 offset. Defaults to 0.
231		ttl (int): Packet time-to-live. Defaults to 255
232		protocol (int): Upper layer protocol number. Defaults to 0.
233		checksum (int): Header checksum. Defaults to 0.
234		source (str): Source IPv4 address. Defaults to "0.0.0.0"
235		destination (str): Destination IPv4 address. Defaults to "0.0.0.0"
236		options (bytes): IP options. Defaults to empty bytes.
237		data (bytes): Packet data. Defaults to empty bytes.
238		"""
239	1	super().__init__()
240	1	self.version = version
241	1	self.ihl = ihl
242	1	self.dscp = dscp
243	1	self.ecn = ecn
244	1	self.length = length
245	1	self.identification = identification
246	1	self.flags = flags
247	1	self.offset = offset
248	1	self.ttl = ttl
249	1	self.protocol = protocol
250	1	self.checksum = checksum
251	1	self.source = source
252	1	self.destination = destination
253	1	self.options = options
254	1	self.data = data
255
256	1	def _update_checksum(self):
257		"""Update the packet checksum to enable integrity check."""
258	1	source_list = [int(octet) for octet in self.source.split(".")]
259	1	destination_list = [int(octet) for octet in
260		self.destination.split(".")]
261	1	source_upper = (source_list[0] << 8) + source_list[1]
262	1	source_lower = (source_list[2] << 8) + source_list[3]
263	1	destination_upper = (destination_list[0] << 8) + destination_list[1]
264	1	destination_lower = (destination_list[2] << 8) + destination_list[3]
265
266	1	block_sum = ((self._version_ihl << 8 \| self._dscp_ecn) + self.length +
267		self.identification + self._flags_offset +
268		(self.ttl << 8 \| self.protocol) + source_upper +
269		source_lower + destination_upper + destination_lower)
270
271	1	while block_sum > 65535:
272	1	carry = block_sum >> 16
273	1	block_sum = (block_sum & 65535) + carry
274
275	1	self.checksum = ~block_sum & 65535
276
277	1	def pack(self, value=None):
278		"""Pack the struct in a binary representation.
279
280		Merge some fields to ensure correct packing.
281
282		Returns:
283		bytes: Binary representation of this instance.
284		"""
285		# Set the correct IHL based on options size
286	1	if self.options:
287	1	self.ihl += int(len(self.options) / 4)
288
289		# Set the correct packet length based on header length and data
290	1	self.length = int(self.ihl * 4 + len(self.data))
291
292	1	self._version_ihl = self.version << 4 \| self.ihl
293	1	self._dscp_ecn = self.dscp << 2 \| self.ecn
294	1	self._flags_offset = self.flags << 13 \| self.offset
295
296		# Set the checksum field before packing
297	1	self._update_checksum()
298
299	1	return super().pack()
300
301	1	def unpack(self, buff, offset=0):
302		"""Unpack a binary struct into this object's attributes.
303
304		Return the values instead of the lib's basic types.
305
306		Args:
307		buff (bytes): Binary buffer.
308		offset (int): Where to begin unpacking.
309
310		Raises:
311		:exc:`~.exceptions.UnpackException`: If unpack fails.
312		"""
313	1	super().unpack(buff, offset)
314
315	1	self.version = self._version_ihl.value >> 4
316	1	self.ihl = self._version_ihl.value & 15
317	1	self.dscp = self._dscp_ecn.value >> 2
318	1	self.ecn = self._dscp_ecn.value & 3
319	1	self.length = self.length.value
320	1	self.identification = self.identification.value
321	1	self.flags = self._flags_offset.value >> 13
322	1	self.offset = self._flags_offset.value & 8191
323	1	self.ttl = self.ttl.value
324	1	self.protocol = self.protocol.value
325	1	self.checksum = self.checksum.value
326	1	self.source = self.source.value
327	1	self.destination = self.destination.value
328
329	1	if self.ihl > 5:
330	1	options_size = (self.ihl - 5) * 4
331	1	self.data = self.options.value[options_size:]
332	1	self.options = self.options.value[:options_size]
333		else:
334		self.data = self.options.value
335		self.options = b''
336
337
338	1	class TLVWithSubType(GenericTLV):
339		"""Modify the :class:`GenericTLV` to a Organization Specific TLV structure.
340
341		Beyond the standard TLV (type, length, value), we can also have a more
342		specific structure, with the :attr:`value` field being splitted into a
343		:attr:`sub_type` field and a new :attr:`sub_value` field.
344		"""
345
346	1	def __init__(self, tlv_type=1, sub_type=7, sub_value=BinaryData()):
347		"""Create an instance and set its attributes.
348
349		Args:
350		tlv_type (int): Type used by this class. Defaults to 1.
351		sub_type (int): Sub type value used by this class. Defaults to 7.
352		sub_value (:class:`~pyof.foundation.basic_types.BinaryData`):
353		Data stored by TLVWithSubType. Defaults to empty BinaryData.
354		"""
355	1	super().__init__(tlv_type)
356	1	self.sub_type = sub_type
357	1	self.sub_value = sub_value
358
359	1	@property
360		def value(self):
361		"""Return sub type and sub value as binary data.
362
363		Returns:
364		:class:`~pyof.foundation.basic_types.BinaryData`:
365		BinaryData calculated.
366		"""
367		binary = UBInt8(self.sub_type).pack() + self.sub_value.pack()
368		return BinaryData(binary)
369
370	1	def unpack(self, buffer, offset=0):
371		"""Unpack a binary message into this object's attributes.
372
373		Unpack the binary value buff and update this object attributes based
374		on the results.
375
376		Args:
377		buff (bytes): Binary data package to be unpacked.
378		offset (int): Where to begin unpacking.
379
380		Raises:
381		Exception: If there is a struct unpacking error.
382		"""
383		header = UBInt16()
384		header.unpack(buffer[offset:offset+2])
385		self.tlv_type = header.value >> 9
386		length = header.value & 511
387		begin, end = offset + 2, offset + 2 + length
388		sub_type = UBInt8()
389		sub_type.unpack(buffer[begin:begin+1])
390		self.sub_type = sub_type.value
391		self.sub_value = BinaryData(buffer[begin+1:end])
392
393
394	1	class LLDP(GenericStruct):
395		"""LLDP class.
396
397		Build a LLDP packet with TLVSubtype and Generic Subtypes.
398
399		It contains a chassis_id TLV, a port_id TLV, a TTL (Time to live) and
400		another TLV to represent the end of the LLDP Packet.
401		"""
402
403		#: chassis_id (:class:`~TLVWithSubType`) with tlv_type = 1 and sub_type = 7
404	1	chassis_id = TLVWithSubType(tlv_type=1, sub_type=7)
405		#: port_id (:class:`TLVWithSubType`) with tlv = 2 and sub_type = 7
406	1	port_id = TLVWithSubType(tlv_type=2, sub_type=7)
407		#: TTL (:class:`GenericTLV`) time is given in seconds, between 0 and 65535,
408		#: with tlv_type = 3
409	1	ttl = GenericTLV(tlv_type=3, value=UBInt16(120))
410		# We are not using list of tlvs for now
411		# tlvs = ListOfTLVs()
412		#: end (:class:`GenericTLV`) with tlv_type = 0
413		end = GenericTLV(tlv_type=0)
414

kytos / python-openflow

Pull Request — master (#425)

GenericTLV.get_size() A

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