# This file is part of Scapy
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# See http://www.secdev.org/projects/scapy for more informations
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# Copyright (C) Santiago Hernandez Ramos <shramos@protonmail.com>
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# This program is published under GPLv2 license
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from scapy.packet import Packet, bind_layers
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from scapy.fields import FieldLenField, BitEnumField, StrLenField, \
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ShortField, ConditionalField, ByteEnumField, ByteField, StrNullField
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from scapy.layers.inet import TCP
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from scapy.error import Scapy_Exception
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from scapy.compat import orb, chb
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# CUSTOM FIELDS
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# source: http://stackoverflow.com/a/43717630
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class VariableFieldLenField(FieldLenField):
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def addfield(self, pkt, s, val):
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val = self.i2m(pkt, val)
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data = []
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while val:
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if val > 127:
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data.append(val & 127)
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val /= 127
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else:
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data.append(val)
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lastoffset = len(data) - 1
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data = b"".join(chb(val | (0 if i == lastoffset else 128))
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for i, val in enumerate(data))
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return s + data
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if len(data) > 3:
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raise Scapy_Exception("%s: malformed length field" %
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self.__class__.__name__)
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def getfield(self, pkt, s):
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value = 0
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for offset, curbyte in enumerate(s):
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curbyte = orb(curbyte)
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value += (curbyte & 127) * (128 ** offset)
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if curbyte & 128 == 0:
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return s[offset + 1:], value
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if offset > 2:
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raise Scapy_Exception("%s: malformed length field" %
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self.__class__.__name__)
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# LAYERS
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CONTROL_PACKET_TYPE = {1: 'CONNECT',
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2: 'CONNACK',
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3: 'PUBLISH',
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4: 'PUBACK',
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5: 'PUBREC',
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6: 'PUBREL',
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7: 'PUBCOMP',
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8: 'SUBSCRIBE',
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9: 'SUBACK',
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10: 'UNSUBSCRIBE',
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11: 'UNSUBACK',
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12: 'PINGREQ',
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13: 'PINGRESP',
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14: 'DISCONNECT'}
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QOS_LEVEL = {0: 'At most once delivery',
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1: 'At least once delivery',
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2: 'Exactly once delivery'}
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# source: http://stackoverflow.com/a/43722441
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class MQTT(Packet):
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name = "MQTT fixed header"
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fields_desc = [
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BitEnumField("type", 1, 4, CONTROL_PACKET_TYPE),
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BitEnumField("DUP", 0, 1, {0: 'Disabled',
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1: 'Enabled'}),
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BitEnumField("QOS", 0, 2, QOS_LEVEL),
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BitEnumField("RETAIN", 0, 1, {0: 'Disabled',
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1: 'Enabled'}),
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# Since the size of the len field depends on the next layer, we need
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# to "cheat" with the length_of parameter and use adjust parameter to
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# calculate the value.
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VariableFieldLenField("len", None, length_of="len",
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adjust=lambda pkt, x: len(pkt.payload),),
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]
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class MQTTConnect(Packet):
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name = "MQTT connect"
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fields_desc = [
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FieldLenField("length", None, length_of="protoname"),
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StrLenField("protoname", "",
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length_from=lambda pkt: pkt.length),
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ByteField("protolevel", 0),
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BitEnumField("usernameflag", 0, 1, {0: 'Disabled',
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1: 'Enabled'}),
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BitEnumField("passwordflag", 0, 1, {0: 'Disabled',
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1: 'Enabled'}),
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BitEnumField("willretainflag", 0, 1, {0: 'Disabled',
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1: 'Enabled'}),
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BitEnumField("willQOSflag", 0, 2, QOS_LEVEL),
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BitEnumField("willflag", 0, 1, {0: 'Disabled',
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1: 'Enabled'}),
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BitEnumField("cleansess", 0, 1, {0: 'Disabled',
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1: 'Enabled'}),
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BitEnumField("reserved", 0, 1, {0: 'Disabled',
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1: 'Enabled'}),
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ShortField("klive", 0),
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FieldLenField("clientIdlen", None, length_of="clientId"),
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StrLenField("clientId", "",
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length_from=lambda pkt: pkt.clientIdlen),
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# Payload with optional fields depending on the flags
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ConditionalField(FieldLenField("wtoplen", None, length_of="willtopic"),
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lambda pkt: pkt.willflag == 1),
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ConditionalField(StrLenField("willtopic", "",
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length_from=lambda pkt: pkt.wtoplen),
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lambda pkt: pkt.willflag == 1),
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ConditionalField(FieldLenField("wmsglen", None, length_of="willmsg"),
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lambda pkt: pkt.willflag == 1),
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ConditionalField(StrLenField("willmsg", "",
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length_from=lambda pkt: pkt.wmsglen),
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lambda pkt: pkt.willflag == 1),
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ConditionalField(FieldLenField("userlen", None, length_of="username"),
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lambda pkt: pkt.usernameflag == 1),
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ConditionalField(StrLenField("username", "",
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length_from=lambda pkt: pkt.userlen),
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lambda pkt: pkt.usernameflag == 1),
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ConditionalField(FieldLenField("passlen", None, length_of="password"),
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lambda pkt: pkt.passwordflag == 1),
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ConditionalField(StrLenField("password", "",
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length_from=lambda pkt: pkt.passlen),
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lambda pkt: pkt.passwordflag == 1),
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]
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RETURN_CODE = {0: 'Connection Accepted',
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1: 'Unacceptable protocol version',
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2: 'Identifier rejected',
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3: 'Server unavailable',
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4: 'Bad username/password',
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5: 'Not authorized'}
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class MQTTConnack(Packet):
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name = "MQTT connack"
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fields_desc = [
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ByteField("sessPresentFlag", 0),
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ByteEnumField("retcode", 0, RETURN_CODE),
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# this package has not payload
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]
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class MQTTPublish(Packet):
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name = "MQTT publish"
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fields_desc = [
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FieldLenField("length", None, length_of="topic"),
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StrLenField("topic", "",
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length_from=lambda pkt: pkt.length),
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ConditionalField(ShortField("msgid", None),
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lambda pkt: (pkt.underlayer.QOS == 1
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or pkt.underlayer.QOS == 2)),
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StrLenField("value", "",
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length_from=lambda pkt: (pkt.underlayer.len -
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pkt.length - 2)),
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]
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class MQTTPuback(Packet):
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name = "MQTT puback"
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fields_desc = [
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ShortField("msgid", None),
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]
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class MQTTPubrec(Packet):
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name = "MQTT pubrec"
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fields_desc = [
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ShortField("msgid", None),
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]
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class MQTTPubrel(Packet):
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name = "MQTT pubrel"
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fields_desc = [
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ShortField("msgid", None),
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]
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class MQTTPubcomp(Packet):
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name = "MQTT pubcomp"
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fields_desc = [
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ShortField("msgid", None),
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]
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class MQTTSubscribe(Packet):
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name = "MQTT subscribe"
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fields_desc = [
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ShortField("msgid", None),
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FieldLenField("length", None, length_of="topic"),
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StrLenField("topic", "",
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length_from=lambda pkt: pkt.length),
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ByteEnumField("QOS", 0, QOS_LEVEL),
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]
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ALLOWED_RETURN_CODE = {0: 'Success',
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1: 'Success',
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2: 'Success',
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128: 'Failure'}
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class MQTTSuback(Packet):
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name = "MQTT suback"
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fields_desc = [
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ShortField("msgid", None),
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ByteEnumField("retcode", None, ALLOWED_RETURN_CODE)
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]
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class MQTTUnsubscribe(Packet):
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name = "MQTT unsubscribe"
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fields_desc = [
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ShortField("msgid", None),
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StrNullField("payload", "")
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]
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class MQTTUnsuback(Packet):
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name = "MQTT unsuback"
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fields_desc = [
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ShortField("msgid", None)
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]
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# LAYERS BINDINGS
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bind_layers(TCP, MQTT, sport=1883)
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bind_layers(TCP, MQTT, dport=1883)
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bind_layers(MQTT, MQTTConnect, type=1)
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bind_layers(MQTT, MQTTConnack, type=2)
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bind_layers(MQTT, MQTTPublish, type=3)
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bind_layers(MQTT, MQTTPuback, type=4)
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bind_layers(MQTT, MQTTPubrec, type=5)
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bind_layers(MQTT, MQTTPubrel, type=6)
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bind_layers(MQTT, MQTTPubcomp, type=7)
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bind_layers(MQTT, MQTTSubscribe, type=8)
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bind_layers(MQTT, MQTTSuback, type=9)
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bind_layers(MQTT, MQTTUnsubscribe, type=10)
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bind_layers(MQTT, MQTTUnsuback, type=11)
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bind_layers(MQTTConnect, MQTT)
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bind_layers(MQTTConnack, MQTT)
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bind_layers(MQTTPublish, MQTT)
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bind_layers(MQTTPuback, MQTT)
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bind_layers(MQTTPubrec, MQTT)
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bind_layers(MQTTPubrel, MQTT)
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bind_layers(MQTTPubcomp, MQTT)
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bind_layers(MQTTSubscribe, MQTT)
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bind_layers(MQTTSuback, MQTT)
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bind_layers(MQTTUnsubscribe, MQTT)
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bind_layers(MQTTUnsuback, MQTT)
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