ARP.unpack() - Code Metrics - Inspection of "Add ARP class" - kytos/python-openflow - Measure and Improve Code Quality continuously with Scrutinizer

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Pull Request — master (#433)

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created 2017-08-02 18:56 UTC

ARP.unpack() A

↳ Parent: ARP

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Lines	0
Ratio	0 %

Code Coverage

Tests	4
CRAP Score	2

Importance

Changes	1
Bugs	0	Features	0

Metric	Value
c	1
b	0
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dl	0
loc	17
ccs	4
cts	4
cp	1
rs	9.4285
cc	2
crap	2

"""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.constants import VLAN_TPID
from pyof.foundation.exceptions import PackException, UnpackException

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


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

    Contains fields for an ARP packet's header and data.
    Designed for Ethernet and IPv4 only: needs to have some attributes changed
    for other HTYPE and PTYPE implementations.
    Must be encapsulated inside an Ethernet frame.
    """

    #: htype (:class:`UBInt16`): The L2 (hardware) protocol type.
    htype = UBInt16()
    #: ptype (:class:`UBInt16`): The L3 protocol type.
    ptype = UBInt16()
    #: hlen (:class:`UBInt8`): Length of hardware address.
    hlen = UBInt8()
    #: plen (:class:`UBInt8`): Length of network protocol address.
    plen = UBInt8()
    #: operation (:class:`UBInt16`): Determines if it is an ARP request
    #: or reply.
    oper = UBInt16()
    #: sha (:class:`HWAddress`): Sender Hardware Address
    sha = HWAddress()
    #: spa (:class:`IPAddress`): Sender Protocol Address
    spa = IPAddress()
    #: tha (:class:`HWAddress`): Target Hardware Address
    tha = HWAddress()
    #: tpa (:class:`IPAddress`): Target Protocol Address
    tpa = IPAddress()

    def __init__(self, htype=1, ptype=0x800, hlen=6, plen=4, oper=1,
                 sha='00:00:00:00:00:00', spa='0.0.0.0',
                 tha="00:00:00:00:00:00", tpa='0.0.0.0'):
        """The constructor receives the parameters below.

        Args:
            htype (int): Hardware protocol type. Defaults to 1 for Ethernet.
            ptype (int): Network protocol type. Defaults to 0x800 for IPv4.
            hlen (int): Length of the hardware address. Defaults to 6 for MAC
                        addresses.
            plen (int): Length of the networking protocol address. Defaults to
                        4 for IPv4 addresses.
            oper (int): Determines the operation for this ARP packet. Must be 1
                        for ARP request or 2 for ARP reply. Defaults to 1.
            sha (str): Sender hardware address. Defaults to
                       '00:00:00:00:00:00'.
            spa (str): Sender protocol address. Defaults to '0.0.0.0'.
            tha (str): Target hardware address. Defaults to
                       '00:00:00:00:00:00'.
            tpa (str): Target protocol address. Defaults to '0.0.0.0'.
        """
        super().__init__()
        self.htype = htype
        self.ptype = ptype
        self.hlen = hlen
        self.plen = plen
        self.oper = oper
        self.sha = sha
        self.spa = spa
        self.tha = tha
        self.tpa = tpa

    def is_valid(self):
        """Assure the ARP contains Ethernet and IPv4 information."""
        return self.htype == 1 and self.ptype == 0x800

    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.
        Check if the protocols involved are Ethernet and IPv4. Other protocols
        are currently not supported.

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

        Raises:
            :exc:`~.exceptions.UnpackException`: If unpack fails.
        """
        super().unpack(buff, offset)
        if not self.is_valid():
            raise UnpackException("Unsupported protocols in ARP packet")


class VLAN(GenericStruct):
    """802.1q VLAN header."""

    #: tpid (:class:`UBInt16`): Tag Protocol Identifier
    tpid = UBInt16(VLAN_TPID)
    #: _tci (:class:`UBInt16`): Tag Control Information - has the
    #: Priority Code Point, DEI/CFI bit and the VLAN ID
    _tci = UBInt16()

    def __init__(self, pcp=None, cfi=None, vid=None):
        """The constructor receives the parameters below.

        If no arguments are set for a particular instance, it is interpreted as
        abscence of VLAN information, and the pack() method will return an
        empty binary string.

        Args:
            tpid (int): Tag Protocol Identifier. Defaults to 0x8100 for 802.1q.
            pcp (int): 802.1p Priority Code Point. Defaults to 0 for Best
                       Effort Queue.
            cfi (int): Canonical Format Indicator. Defaults to 0 for Ethernet.
            vid (int): VLAN ID. If no VLAN is specified, value is 0.
        """
        super().__init__()
        self.tpid = VLAN_TPID
        self.pcp = pcp
        self.cfi = cfi
        self.vid = vid

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

        Merge some fields to ensure correct packing.

        If no arguments are set for a particular instance, it is interpreted as
        abscence of VLAN information, and the pack() method will return an
        empty binary string.

        Returns:
            bytes: Binary representation of this instance.
        """
        if isinstance(value, type(self)):
            return value.pack()

        if self.pcp is None and self.cfi is None and self.vid is None:
            return b''
        self.pcp = self.pcp if self.pcp is not None else 0
        self.cfi = self.cfi if self.cfi is not None else 0
        self.vid = self.vid if self.vid is not None else 0
        self._tci = self.pcp << 13 | self.cfi << 12 | self.vid
        return super().pack()

    def _validate(self):
        """Assure this is a 802.1q VLAN header instance."""
        if self.tpid.value != VLAN_TPID:
            raise UnpackException
        return

    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.

        After unpacking, the abscence of a `tpid` value causes the assignment
        of None to the field values to indicate that there is no VLAN
        information.

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

        Raises:
            :exc:`~.exceptions.UnpackException`: If unpack fails.
        """
        super().unpack(buff, offset)
        if self.tpid.value:
            self._validate()
            self.tpid = self.tpid.value
            self.pcp = self._tci.value >> 13
            self.cfi = (self._tci.value >> 12) & 1
            self.vid = self._tci.value & 4095
        else:
            self.tpid = VLAN_TPID
            self.pcp = None
            self.cfi = None
            self.vid = None


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()
    vlan = VLAN()
    ether_type = UBInt16()
    data = BinaryData()

    def __init__(self, destination=None, source=None, vlan=VLAN(),
                 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.vlan = vlan
        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())

    def unpack(self, buff, 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.

        Ethernet headers may have VLAN tags. If no VLAN tag is found, a
        'wildcard VLAN tag' is inserted to assure correct unpacking.

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

        Raises:
            UnpackException: If there is a struct unpacking error.
        """
        # Checking if the EtherType bytes are actually equal to VLAN_TPID -
        # indicating that the packet is tagged. If it is not, we insert the
        # equivalent to 'NULL VLAN data' (\x00\x00\x00\x00) to enable the
        # correct unpacking process.
        if buff[12:16] != VLAN_TPID.to_bytes(2, 'big'):
            buff = buff[0:12] + b'\x00\x00\x00\x00' + buff[12:]

        super().unpack(buff, offset)


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 constructor 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.constants import VLAN_TPID
10	1	from pyof.foundation.exceptions import PackException, UnpackException
11
12	1	__all__ = ('ARP', 'Ethernet', 'GenericTLV', 'IPv4', 'VLAN', 'TLVWithSubType',
13		'LLDP')
14
15
16	1	class ARP(GenericStruct):
17		"""ARP packet "struct".
18
19		Contains fields for an ARP packet's header and data.
20		Designed for Ethernet and IPv4 only: needs to have some attributes changed
21		for other HTYPE and PTYPE implementations.
22		Must be encapsulated inside an Ethernet frame.
23		"""
24
25		#: htype (:class:`UBInt16`): The L2 (hardware) protocol type.
26	1	htype = UBInt16()
27		#: ptype (:class:`UBInt16`): The L3 protocol type.
28	1	ptype = UBInt16()
29		#: hlen (:class:`UBInt8`): Length of hardware address.
30	1	hlen = UBInt8()
31		#: plen (:class:`UBInt8`): Length of network protocol address.
32	1	plen = UBInt8()
33		#: operation (:class:`UBInt16`): Determines if it is an ARP request
34		#: or reply.
35	1	oper = UBInt16()
36		#: sha (:class:`HWAddress`): Sender Hardware Address
37	1	sha = HWAddress()
38		#: spa (:class:`IPAddress`): Sender Protocol Address
39	1	spa = IPAddress()
40		#: tha (:class:`HWAddress`): Target Hardware Address
41	1	tha = HWAddress()
42		#: tpa (:class:`IPAddress`): Target Protocol Address
43	1	tpa = IPAddress()
44
45	1	def __init__(self, htype=1, ptype=0x800, hlen=6, plen=4, oper=1,
46		sha='00:00:00:00:00:00', spa='0.0.0.0',
47		tha="00:00:00:00:00:00", tpa='0.0.0.0'):
48		"""The constructor receives the parameters below.
49
50		Args:
51		htype (int): Hardware protocol type. Defaults to 1 for Ethernet.
52		ptype (int): Network protocol type. Defaults to 0x800 for IPv4.
53		hlen (int): Length of the hardware address. Defaults to 6 for MAC
54		addresses.
55		plen (int): Length of the networking protocol address. Defaults to
56		4 for IPv4 addresses.
57		oper (int): Determines the operation for this ARP packet. Must be 1
58		for ARP request or 2 for ARP reply. Defaults to 1.
59		sha (str): Sender hardware address. Defaults to
60		'00:00:00:00:00:00'.
61		spa (str): Sender protocol address. Defaults to '0.0.0.0'.
62		tha (str): Target hardware address. Defaults to
63		'00:00:00:00:00:00'.
64		tpa (str): Target protocol address. Defaults to '0.0.0.0'.
65		"""
66	1	super().__init__()
67	1	self.htype = htype
68	1	self.ptype = ptype
69	1	self.hlen = hlen
70	1	self.plen = plen
71	1	self.oper = oper
72	1	self.sha = sha
73	1	self.spa = spa
74	1	self.tha = tha
75	1	self.tpa = tpa
76
77	1	def is_valid(self):
78		"""Assure the ARP contains Ethernet and IPv4 information."""
79	1	return self.htype == 1 and self.ptype == 0x800
80
81	1	def unpack(self, buff, offset=0):
82		"""Unpack a binary struct into this object's attributes.
83
84		Return the values instead of the lib's basic types.
85		Check if the protocols involved are Ethernet and IPv4. Other protocols
86		are currently not supported.
87
88		Args:
89		buff (bytes): Binary buffer.
90		offset (int): Where to begin unpacking.
91
92		Raises:
93		:exc:`~.exceptions.UnpackException`: If unpack fails.
94		"""
95	1	super().unpack(buff, offset)
96	1	if not self.is_valid():
97	1	raise UnpackException("Unsupported protocols in ARP packet")
98
99
100	1	class VLAN(GenericStruct):
101		"""802.1q VLAN header."""
102
103		#: tpid (:class:`UBInt16`): Tag Protocol Identifier
104	1	tpid = UBInt16(VLAN_TPID)
105		#: _tci (:class:`UBInt16`): Tag Control Information - has the
106		#: Priority Code Point, DEI/CFI bit and the VLAN ID
107	1	_tci = UBInt16()
108
109	1	def __init__(self, pcp=None, cfi=None, vid=None):
110		"""The constructor receives the parameters below.
111
112		If no arguments are set for a particular instance, it is interpreted as
113		abscence of VLAN information, and the pack() method will return an
114		empty binary string.
115
116		Args:
117		tpid (int): Tag Protocol Identifier. Defaults to 0x8100 for 802.1q.
118		pcp (int): 802.1p Priority Code Point. Defaults to 0 for Best
119		Effort Queue.
120		cfi (int): Canonical Format Indicator. Defaults to 0 for Ethernet.
121		vid (int): VLAN ID. If no VLAN is specified, value is 0.
122		"""
123	1	super().__init__()
124	1	self.tpid = VLAN_TPID
125	1	self.pcp = pcp
126	1	self.cfi = cfi
127	1	self.vid = vid
128
129	1	def pack(self, value=None):
130		"""Pack the struct in a binary representation.
131
132		Merge some fields to ensure correct packing.
133
134		If no arguments are set for a particular instance, it is interpreted as
135		abscence of VLAN information, and the pack() method will return an
136		empty binary string.
137
138		Returns:
139		bytes: Binary representation of this instance.
140		"""
141	1	if isinstance(value, type(self)):
142	1	return value.pack()
143
144	1	if self.pcp is None and self.cfi is None and self.vid is None:
145	1	return b''
146	1	self.pcp = self.pcp if self.pcp is not None else 0
147	1	self.cfi = self.cfi if self.cfi is not None else 0
148	1	self.vid = self.vid if self.vid is not None else 0
149	1	self._tci = self.pcp << 13 \| self.cfi << 12 \| self.vid
150	1	return super().pack()
151
152	1	def _validate(self):
153		"""Assure this is a 802.1q VLAN header instance."""
154	1	if self.tpid.value != VLAN_TPID:
155	1	raise UnpackException
156	1	return
157
158	1	def unpack(self, buff, offset=0):
159		"""Unpack a binary struct into this object's attributes.
160
161		Return the values instead of the lib's basic types.
162
163		After unpacking, the abscence of a `tpid` value causes the assignment
164		of None to the field values to indicate that there is no VLAN
165		information.
166
167		Args:
168		buff (bytes): Binary buffer.
169		offset (int): Where to begin unpacking.
170
171		Raises:
172		:exc:`~.exceptions.UnpackException`: If unpack fails.
173		"""
174	1	super().unpack(buff, offset)
175	1	if self.tpid.value:
176	1	self._validate()
177	1	self.tpid = self.tpid.value
178	1	self.pcp = self._tci.value >> 13
179	1	self.cfi = (self._tci.value >> 12) & 1
180	1	self.vid = self._tci.value & 4095
181		else:
182	1	self.tpid = VLAN_TPID
183	1	self.pcp = None
184	1	self.cfi = None
185	1	self.vid = None
186
187
188	1	class Ethernet(GenericStruct):
189		"""Ethernet "struct".
190
191		Objects of this class represents an ethernet packet. It contains the
192		'Ethernet header', composed by destination (MAC), source (MAC), type
193		(EtherType)[1] and the payload of the packet, as binary data.
194
195		This class does not consider the Ethernet 'Preamble' or the 'CRC'.
196
197		There is also a get_hash method, that hashes the binary representation of
198		the object so we can have a unique representation of the ethernet packet,
199		so we can keep a track of ethernet packets being flooded over the network.
200
201		[1] EtherTypes:
202		http://www.iana.org/assignments/ieee-802-numbers/ieee-802-numbers.xhtml#ieee-802-numbers-1
203		"""
204
205	1	destination = HWAddress()
206	1	source = HWAddress()
207	1	vlan = VLAN()
208	1	ether_type = UBInt16()
209	1	data = BinaryData()
210
211	1	def __init__(self, destination=None, source=None, vlan=VLAN(),
212		ether_type=None, data=b''):
213		"""Create an instance and set its attributes.
214
215		Args:
216		destination (:class:`~pyof.foundation.basic_types.HWAddress`):
217		The final destination MAC address.
218		source (:class:`~pyof.foundation.basic_types.HWAddress`):
219		The source Mac address of the packet.
220		ether_type (:class:`~pyof.foundation.basic_types.UBInt16`):
221		The EtherType of packet.
222		data (:class:`~pyof.foundation.basic_types.BinaryData`):
223		The content of the packet in binary format.
224		"""
225	1	super().__init__()
226	1	self.destination = destination
227	1	self.source = source
228	1	self.vlan = vlan
229	1	self.ether_type = ether_type
230	1	self.data = data
231
232	1	def get_hash(self):
233		"""Calculate a hash and returns it.
234
235		Returns:
236		int: Integer value that identifies this instance.
237		"""
238		return hash(self.pack())
239
240	1	def unpack(self, buff, offset=0):
241		"""Unpack a binary message into this object's attributes.
242
243		Unpack the binary value buff and update this object attributes based
244		on the results.
245
246		Ethernet headers may have VLAN tags. If no VLAN tag is found, a
247		'wildcard VLAN tag' is inserted to assure correct unpacking.
248
249		Args:
250		buff (bytes): Binary data package to be unpacked.
251		offset (int): Where to begin unpacking.
252
253		Raises:
254		UnpackException: If there is a struct unpacking error.
255		"""
256		# Checking if the EtherType bytes are actually equal to VLAN_TPID -
257		# indicating that the packet is tagged. If it is not, we insert the
258		# equivalent to 'NULL VLAN data' (\x00\x00\x00\x00) to enable the
259		# correct unpacking process.
260	1	if buff[12:16] != VLAN_TPID.to_bytes(2, 'big'):
261	1	buff = buff[0:12] + b'\x00\x00\x00\x00' + buff[12:]
262
263	1	super().unpack(buff, offset)
264
265
266	1	class GenericTLV(GenericStruct):
267		"""TLV structure of LLDP packets.
268
269		This is a Type, Length and Value (TLV) struct.
270
271		The LLDP/TLV definition states that the Type field have 7 bits, while
272		the length have 9 bits. The Value must be between 0-511 octets.
273
274		Internally, on the instances of this class, the Type is a integer
275		(0-127) and the Length is dynamically calculated based on the current
276		type and value.
277		"""
278
279	1	def __init__(self, tlv_type=127, value=BinaryData()):
280		"""Create an instance and set its attributes.
281
282		Args:
283		tlv_type (int): Type used by this class. Defaults to 127.
284		value (:class:`~pyof.foundation.basic_types.BinaryData`):
285		Value stored by GenericTLV.
286		"""
287	1	super().__init__()
288	1	self.tlv_type = tlv_type
289	1	self._value = value
290
291	1	@property
292		def value(self):
293		"""Return the value stored by GenericTLV.
294
295		Returns:
296		:class:`~pyof.foundation.basic_types.BinaryData`:
297		Value stored by GenericTLV.
298		"""
299	1	return self._value
300
301	1	@property
302		def length(self):
303		"""Return the length of value stored by GenericTLV.
304
305		Returns:
306		int: Value length in bytes.
307		"""
308	1	return len(self.value.pack())
309
310	1	@property
311		def header(self):
312		"""Header of the TLV Packet.
313
314		The header is composed by the Type (7 bits) and Length (9 bits),
315		summing up 16 bits. To achieve that, we need to do some bitshift
316		operations.
317
318		Returns:
319		:class:`~pyof.foundation.basic_types.UBInt16`:
320		Result after all operations.
321		"""
322	1	return UBInt16(((self.tlv_type & 127) << 9) \| (self.length & 511))
323
324	1	def pack(self, value=None):
325		"""Pack the TLV in a binary representation.
326
327		Returns:
328		bytes: Binary representation of the struct object.
329
330		Raises:
331		:exc:`~.exceptions.ValidationError`: If validation fails.
332		"""
333	1	if value is None:
334	1	output = self.header.pack()
335	1	output += self.value.pack()
336	1	return output
337
338		elif isinstance(value, type(self)):
339		return value.pack()
340		else:
341		msg = "{} is not an instance of {}".format(value,
342		type(self).__name__)
343		raise PackException(msg)
344
345	1	def unpack(self, buffer, offset=0):
346		"""Unpack a binary message into this object's attributes.
347
348		Unpack the binary value buff and update this object attributes based
349		on the results.
350
351		Args:
352		buff (bytes): Binary data package to be unpacked.
353		offset (int): Where to begin unpacking.
354
355		Raises:
356		Exception: If there is a struct unpacking error.
357		"""
358	1	header = UBInt16()
359	1	header.unpack(buffer[offset:offset+2])
360	1	self.tlv_type = header.value >> 9
361	1	length = header.value & 511
362	1	begin, end = offset + 2, offset + 2 + length
363	1	self._value = BinaryData(buffer[begin:end])
364
365	1	def get_size(self, value=None):
366		"""Return struct size.
367
368		Returns:
369		int: Returns the struct size based on inner attributes.
370		"""
371		if isinstance(value, type(self)):
372		return value.get_size()
373
374		return 2 + self.length
375
376
377	1	class IPv4(GenericStruct):
378		"""IPv4 packet "struct".
379
380		Contains all fields of an IP version 4 packet header, plus the upper layer
381		content as binary data.
382		Some of the fields were merged together because of their size being
383		inferior to 8 bits. They are represented as a single class attribute, but
384		pack/unpack methods will take into account the values in individual
385		instance attributes.
386		"""
387
388		#: _version_ihl (:class:`UBInt8`): IP protocol version + Internet Header
389		#: Length (words)
390	1	_version_ihl = UBInt8()
391		#: _dscp_ecn (:class:`UBInt8`): Differentiated Services Code Point
392		#: (ToS - Type of Service) + Explicit Congestion Notification
393	1	_dscp_ecn = UBInt8()
394		#: length (:class:`UBInt16`): IP packet length (bytes)
395	1	length = UBInt16()
396		#: identification (:class:`UBInt16`): Packet ID - common to all fragments
397	1	identification = UBInt16()
398		#: _flags_offset (:class:`UBInt16`): Fragmentation flags + fragmentation
399		#: offset
400	1	_flags_offset = UBInt16()
401		#: ttl (:class:`UBInt8`): Packet time-to-live
402	1	ttl = UBInt8()
403		#: protocol (:class:`UBInt8`): Upper layer protocol number
404	1	protocol = UBInt8()
405		#: checksum (:class:`UBInt16`): Header checksum
406	1	checksum = UBInt16()
407		#: source (:class:`IPAddress`): Source IPv4 address
408	1	source = IPAddress()
409		#: destination (:class:`IPAddress`): Destination IPv4 address
410	1	destination = IPAddress()
411		#: options (:class:`BinaryData`): IP Options - up to 320 bits, always
412		#: padded to 32 bits
413	1	options = BinaryData()
414		#: data (:class:`BinaryData`): Packet data
415	1	data = BinaryData()
416
417	1	def __init__(self, version=4, ihl=5, dscp=0, ecn=0, length=0, # noqa
418		identification=0, flags=0, offset=0, ttl=255, protocol=0,
419		checksum=0, source="0.0.0.0", destination="0.0.0.0",
420		options=b'', data=b''):
421		"""The constructor receives the parameters below.
422
423		Args:
424		version (int): IP protocol version. Defaults to 4.
425		ihl (int): Internet Header Length. Default is 5.
426		dscp (int): Differentiated Service Code Point. Defaults to 0.
427		ecn (int): Explicit Congestion Notification. Defaults to 0.
428		length (int): IP packet length in bytes. Defaults to 0.
429		identification (int): Packet Id. Defaults to 0.
430		flags (int): IPv4 Flags. Defults 0.
431		offset (int): IPv4 offset. Defaults to 0.
432		ttl (int): Packet time-to-live. Defaults to 255
433		protocol (int): Upper layer protocol number. Defaults to 0.
434		checksum (int): Header checksum. Defaults to 0.
435		source (str): Source IPv4 address. Defaults to "0.0.0.0"
436		destination (str): Destination IPv4 address. Defaults to "0.0.0.0"
437		options (bytes): IP options. Defaults to empty bytes.
438		data (bytes): Packet data. Defaults to empty bytes.
439		"""
440	1	super().__init__()
441	1	self.version = version
442	1	self.ihl = ihl
443	1	self.dscp = dscp
444	1	self.ecn = ecn
445	1	self.length = length
446	1	self.identification = identification
447	1	self.flags = flags
448	1	self.offset = offset
449	1	self.ttl = ttl
450	1	self.protocol = protocol
451	1	self.checksum = checksum
452	1	self.source = source
453	1	self.destination = destination
454	1	self.options = options
455	1	self.data = data
456
457	1	def _update_checksum(self):
458		"""Update the packet checksum to enable integrity check."""
459	1	source_list = [int(octet) for octet in self.source.split(".")]
460	1	destination_list = [int(octet) for octet in
461		self.destination.split(".")]
462	1	source_upper = (source_list[0] << 8) + source_list[1]
463	1	source_lower = (source_list[2] << 8) + source_list[3]
464	1	destination_upper = (destination_list[0] << 8) + destination_list[1]
465	1	destination_lower = (destination_list[2] << 8) + destination_list[3]
466
467	1	block_sum = ((self._version_ihl << 8 \| self._dscp_ecn) + self.length +
468		self.identification + self._flags_offset +
469		(self.ttl << 8 \| self.protocol) + source_upper +
470		source_lower + destination_upper + destination_lower)
471
472	1	while block_sum > 65535:
473	1	carry = block_sum >> 16
474	1	block_sum = (block_sum & 65535) + carry
475
476	1	self.checksum = ~block_sum & 65535
477
478	1	def pack(self, value=None):
479		"""Pack the struct in a binary representation.
480
481		Merge some fields to ensure correct packing.
482
483		Returns:
484		bytes: Binary representation of this instance.
485		"""
486		# Set the correct IHL based on options size
487	1	if self.options:
488	1	self.ihl += int(len(self.options) / 4)
489
490		# Set the correct packet length based on header length and data
491	1	self.length = int(self.ihl * 4 + len(self.data))
492
493	1	self._version_ihl = self.version << 4 \| self.ihl
494	1	self._dscp_ecn = self.dscp << 2 \| self.ecn
495	1	self._flags_offset = self.flags << 13 \| self.offset
496
497		# Set the checksum field before packing
498	1	self._update_checksum()
499
500	1	return super().pack()
501
502	1	def unpack(self, buff, offset=0):
503		"""Unpack a binary struct into this object's attributes.
504
505		Return the values instead of the lib's basic types.
506
507		Args:
508		buff (bytes): Binary buffer.
509		offset (int): Where to begin unpacking.
510
511		Raises:
512		:exc:`~.exceptions.UnpackException`: If unpack fails.
513		"""
514	1	super().unpack(buff, offset)
515
516	1	self.version = self._version_ihl.value >> 4
517	1	self.ihl = self._version_ihl.value & 15
518	1	self.dscp = self._dscp_ecn.value >> 2
519	1	self.ecn = self._dscp_ecn.value & 3
520	1	self.length = self.length.value
521	1	self.identification = self.identification.value
522	1	self.flags = self._flags_offset.value >> 13
523	1	self.offset = self._flags_offset.value & 8191
524	1	self.ttl = self.ttl.value
525	1	self.protocol = self.protocol.value
526	1	self.checksum = self.checksum.value
527	1	self.source = self.source.value
528	1	self.destination = self.destination.value
529
530	1	if self.ihl > 5:
531	1	options_size = (self.ihl - 5) * 4
532	1	self.data = self.options.value[options_size:]
533	1	self.options = self.options.value[:options_size]
534		else:
535		self.data = self.options.value
536		self.options = b''
537
538
539	1	class TLVWithSubType(GenericTLV):
540		"""Modify the :class:`GenericTLV` to a Organization Specific TLV structure.
541
542		Beyond the standard TLV (type, length, value), we can also have a more
543		specific structure, with the :attr:`value` field being splitted into a
544		:attr:`sub_type` field and a new :attr:`sub_value` field.
545		"""
546
547	1	def __init__(self, tlv_type=1, sub_type=7, sub_value=BinaryData()):
548		"""Create an instance and set its attributes.
549
550		Args:
551		tlv_type (int): Type used by this class. Defaults to 1.
552		sub_type (int): Sub type value used by this class. Defaults to 7.
553		sub_value (:class:`~pyof.foundation.basic_types.BinaryData`):
554		Data stored by TLVWithSubType. Defaults to empty BinaryData.
555		"""
556	1	super().__init__(tlv_type)
557	1	self.sub_type = sub_type
558	1	self.sub_value = sub_value
559
560	1	@property
561		def value(self):
562		"""Return sub type and sub value as binary data.
563
564		Returns:
565		:class:`~pyof.foundation.basic_types.BinaryData`:
566		BinaryData calculated.
567		"""
568		binary = UBInt8(self.sub_type).pack() + self.sub_value.pack()
569		return BinaryData(binary)
570
571	1	def unpack(self, buffer, offset=0):
572		"""Unpack a binary message into this object's attributes.
573
574		Unpack the binary value buff and update this object attributes based
575		on the results.
576
577		Args:
578		buff (bytes): Binary data package to be unpacked.
579		offset (int): Where to begin unpacking.
580
581		Raises:
582		Exception: If there is a struct unpacking error.
583		"""
584		header = UBInt16()
585		header.unpack(buffer[offset:offset+2])
586		self.tlv_type = header.value >> 9
587		length = header.value & 511
588		begin, end = offset + 2, offset + 2 + length
589		sub_type = UBInt8()
590		sub_type.unpack(buffer[begin:begin+1])
591		self.sub_type = sub_type.value
592		self.sub_value = BinaryData(buffer[begin+1:end])
593
594
595	1	class LLDP(GenericStruct):
596		"""LLDP class.
597
598		Build a LLDP packet with TLVSubtype and Generic Subtypes.
599
600		It contains a chassis_id TLV, a port_id TLV, a TTL (Time to live) and
601		another TLV to represent the end of the LLDP Packet.
602		"""
603
604		#: chassis_id (:class:`~TLVWithSubType`) with tlv_type = 1 and sub_type = 7
605	1	chassis_id = TLVWithSubType(tlv_type=1, sub_type=7)
606		#: port_id (:class:`TLVWithSubType`) with tlv = 2 and sub_type = 7
607	1	port_id = TLVWithSubType(tlv_type=2, sub_type=7)
608		#: TTL (:class:`GenericTLV`) time is given in seconds, between 0 and 65535,
609		#: with tlv_type = 3
610	1	ttl = GenericTLV(tlv_type=3, value=UBInt16(120))
611		# We are not using list of tlvs for now
612		# tlvs = ListOfTLVs()
613		#: end (:class:`GenericTLV`) with tlv_type = 0
614		end = GenericTLV(tlv_type=0)
615

kytos / python-openflow

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