How to use the pypacker.pypacker.get_property_ip4 function in pypacker

"""Internet Group Management Protocol."""

from pypacker import pypacker, checksum
from pypacker.pypacker import FIELD_FLAG_AUTOUPDATE


class IGMP(pypacker.Packet):
	__hdr__ = (
		("type", "B", 0),
		("maxresp", "B", 0),
		("sum", "H", 0, FIELD_FLAG_AUTOUPDATE),
		("group", "4s", b"\x00" * 4)
	)

	# Convenient access for: group[_s]
	group_s = pypacker.get_property_ip4("group")

	def _update_fields(self):
		if self.sum_au_active and self._changed():
			self.sum = 0
			self.sum = checksum.in_cksum(pypacker.Packet.bin(self))

("hrd", "H", ARP_HRD_ETH),
		("pro", "H", ARP_PRO_IP),
		("hln", "B", 6),			# hardware address length
		("pln", "B", 4),			# protocol address length
		("op", "H", ARP_OP_REQUEST),
		("sha", "6s", b"\x00" * 6),		# sender mac
		("spa", "4s", b"\x00" * 4),		# sender ip
		("tha", "6s", b"\x00" * 6),		# target mac
		("tpa", "4s", b"\x00" * 4)		# target ip
	)

	# convenient access
	sha_s = pypacker.get_property_mac("sha")
	spa_s = pypacker.get_property_ip4("spa")
	tha_s = pypacker.get_property_mac("tha")
	tpa_s = pypacker.get_property_ip4("tpa")

("ciaddr", "4s", b"\x00" * 4),
		("yiaddr", "4s", b"\x00" * 4),
		("siaddr", "4s", b"\x00" * 4),
		("giaddr", "4s", b"\x00" * 4),
		# MAC + padding
		("chaddr", "16s", b"\x00" * 6 + b"\x00" * 10),
		("sname", "64s", b"\x00" * 64),
		("file", "128s", b"\x00" * 128),
		("magic", "I", DHCP_MAGIC),
		("opts", None, triggerlist.TriggerList)
	)

	ciaddr_s = pypacker.get_property_ip4("ciaddr")
	yiaddr_s = pypacker.get_property_ip4("yiaddr")
	siaddr_s = pypacker.get_property_ip4("siaddr")
	giaddr_s = pypacker.get_property_ip4("giaddr")

	def _dissect(self, buf):
		# logger.debug("DHCP: parsing options, buflen: %d" % len(buf))
		self._init_triggerlist("opts", buf[28 + 16 + 64 + 128 + 4:], DHCP.__get_opts)
		# logger.debug(buf[28+16+64+128+4:])
		# logger.debug("amount of options after parsing: %d" % len(self.opts))
		return len(buf)

	@staticmethod
	def __get_opts(buf):
		# logger.debug("DHCP: parsing options from: %s" % buf)
		opts = []
		i = 0

		while i < len(buf):
			t = buf[i]

class ARP(pypacker.Packet):
	__hdr__ = (
		("hrd", "H", ARP_HRD_ETH),
		("pro", "H", ARP_PRO_IP),
		("hln", "B", 6),			# hardware address length
		("pln", "B", 4),			# protocol address length
		("op", "H", ARP_OP_REQUEST),
		("sha", "6s", b"\x00" * 6),		# sender mac
		("spa", "4s", b"\x00" * 4),		# sender ip
		("tha", "6s", b"\x00" * 6),		# target mac
		("tpa", "4s", b"\x00" * 4)		# target ip
	)

	# convenient access
	sha_s = pypacker.get_property_mac("sha")
	spa_s = pypacker.get_property_ip4("spa")
	tha_s = pypacker.get_property_mac("tha")
	tpa_s = pypacker.get_property_ip4("tpa")

# Simple constant field, deactivated (see Ethernet -> vlan)
		# Switching between active/inactive should be avoided because of performance penalty :/
		("idk", "H", None),
		# Again a simple constant field
		("flags", "B", 0),
		# Dynamic field: bytestring format, *can* change in length, see dns.DNS
		# Field type should be avoided because of performance penalty :/
		("yolo", None, b"1234"),
		# TriggerList field: variable length, can contain: raw bytes, key/value-tuples (see HTTP) and Packets (see IP)
		# Here TriggerList will contain key/value Tuples like (b"\x00", b"1")
		("options", None, triggerlist.TriggerList)
	)

	# Conveniant access should be enabled using properties eg using pypacker.get_property_xxx(...)
	src_s = pypacker.get_property_ip4("src")
	dst_s = pypacker.get_property_ip4("dst")
	# xxx_s = pypacker.get_property_mac("xxx")
	# xxx_s = pypacker.get_property_dnsname("xxx")

	# Setting/getting values smaller then 1 Byte should be enabled using properties (see layer3/ip.IP -> v, hl)
	def __get_flag_fluxcapacitor(self):
		return (self.flags & 0x80) >> 15

	def __set_flag_fluxcapacitor(self, value):
		value_shift = (value & 1) << 15
		self.flags = (self.flags & ~0x80) | value_shift

	flag_fluxcapacitor = property(__get_flag_fluxcapacitor, __set_flag_fluxcapacitor)

	@staticmethod
	def _parse_options(buf):
		"""

# more fragments follow
				ip_frag.flags = 0x1
			else:
				# last fragment
				ip_frag.flags = 0x0

			ip_frag.offset = int(off / 8)
			ip_frag.body_bytes = payload_sub
			fragments.append(ip_frag)
			off += fragment_len

		return fragments

	# Convenient access for: src[_s], dst[_s]
	src_s = pypacker.get_property_ip4("src")
	dst_s = pypacker.get_property_ip4("dst")

	def _dissect(self, buf):
		total_header_length = ((buf[0] & 0xf) << 2)
		options_length = total_header_length - 20		# total IHL - standard IP-len = options length

		if options_length > 0:
			# logger.debug("got some IP options: %s" % tl_opts)
			self._init_triggerlist("opts", buf[20: 20 + options_length], self._parse_opts)
		elif options_length < 0:
			# invalid header length: assume no options at all
			raise Exception()
		# TODO: extract real data length:
		# There are some cases where padding can not be identified on ethernet -> do it here (eg VSS shit trailer)
		self._init_handler(buf[9], buf[total_header_length:])
		return total_header_length

("static_field0", "B", 123),
		("static_field1", "H", 456),
		("static_field2", "I", 789),
		("static_field3_src", "4s", b"\x00" * 4),
		("static_field4_dst", "4s", b"\x00" * 4),
		# standard dynamic field, no cascading changes needed on changes
		# to this header
		("dynamic_field0", None, triggerlist.TriggerList),
		# specialised dynamic field: update needed on change for subfield
		# (part of static_field1)
		("dynamic_field1", None, DynamicField),
	)

	## convenient access for static_field3_src and static_field4_dst: IP4 address
	src_s = pypacker.get_property_ip4("static_field3_src")
	dst_s = pypacker.get_property_ip4("static_field4_dst")

	## values smaller than 1 Byte
	def __get_v(self):
		return self.static_field1 >> 4

	def __set_v(self, value):
		self.static_field1 = (value << 4) | (self.static_field1 & 0xf)
	subfield = property(__get_v, __set_v)

	def _dissect(self, buf):
		# static part will be unpacked automatically

		# skip 15 Bytes (= B + H + I + 4s + 4s)
		self.dynamic_field0.init_lazy_dissect(buf[15:39], self.__dissect_dynamic0)
		dynlen = buf[0]
		self.dynamic_field1.init_lazy_dissect(buf[39:39 + dynlen], self.__dissect_dynamic1)

("flags", "H", 0),
		("ciaddr", "4s", b"\x00" * 4),
		("yiaddr", "4s", b"\x00" * 4),
		("siaddr", "4s", b"\x00" * 4),
		("giaddr", "4s", b"\x00" * 4),
		# MAC + padding
		("chaddr", "16s", b"\x00" * 6 + b"\x00" * 10),
		("sname", "64s", b"\x00" * 64),
		("file", "128s", b"\x00" * 128),
		("magic", "I", DHCP_MAGIC),
		("opts", None, triggerlist.TriggerList)
	)

	ciaddr_s = pypacker.get_property_ip4("ciaddr")
	yiaddr_s = pypacker.get_property_ip4("yiaddr")
	siaddr_s = pypacker.get_property_ip4("siaddr")
	giaddr_s = pypacker.get_property_ip4("giaddr")

	def _dissect(self, buf):
		# logger.debug("DHCP: parsing options, buflen: %d" % len(buf))
		self._init_triggerlist("opts", buf[28 + 16 + 64 + 128 + 4:], DHCP.__get_opts)
		# logger.debug(buf[28+16+64+128+4:])
		# logger.debug("amount of options after parsing: %d" % len(self.opts))
		return len(buf)

	@staticmethod
	def __get_opts(buf):
		# logger.debug("DHCP: parsing options from: %s" % buf)
		opts = []
		i = 0

		while i < len(buf):

__hdr__ = (
		("static_field0", "B", 123),
		("static_field1", "H", 456),
		("static_field2", "I", 789),
		("static_field3_src", "4s", b"\x00" * 4),
		("static_field4_dst", "4s", b"\x00" * 4),
		# standard dynamic field, no cascading changes needed on changes
		# to this header
		("dynamic_field0", None, triggerlist.TriggerList),
		# specialised dynamic field: update needed on change for subfield
		# (part of static_field1)
		("dynamic_field1", None, DynamicField),
	)

	## convenient access for static_field3_src and static_field4_dst: IP4 address
	src_s = pypacker.get_property_ip4("static_field3_src")
	dst_s = pypacker.get_property_ip4("static_field4_dst")

	## values smaller than 1 Byte
	def __get_v(self):
		return self.static_field1 >> 4

	def __set_v(self, value):
		self.static_field1 = (value << 4) | (self.static_field1 & 0xf)
	subfield = property(__get_v, __set_v)

	def _dissect(self, buf):
		# static part will be unpacked automatically

		# skip 15 Bytes (= B + H + I + 4s + 4s)
		self.dynamic_field0.init_lazy_dissect(buf[15:39], self.__dissect_dynamic0)
		dynlen = buf[0]