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IP6_Address.py
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IP6_Address.py
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# Impacket - Collection of Python classes for working with network protocols.
#
# SECUREAUTH LABS. Copyright (C) 2018 SecureAuth Corporation. All rights reserved.
#
# This software is provided under a slightly modified version
# of the Apache Software License. See the accompanying LICENSE file
# for more information.
#
import array
from six import string_types
class IP6_Address:
ADDRESS_BYTE_SIZE = 16
#A Hex Group is a 16-bit unit of the address
TOTAL_HEX_GROUPS = 8
HEX_GROUP_SIZE = 4 #Size in characters
TOTAL_SEPARATORS = TOTAL_HEX_GROUPS - 1
ADDRESS_TEXT_SIZE = (TOTAL_HEX_GROUPS * HEX_GROUP_SIZE) + TOTAL_SEPARATORS
SEPARATOR = ":"
SCOPE_SEPARATOR = "%"
#############################################################################################################
# Constructor and construction helpers
def __init__(self, address):
#The internal representation of an IP6 address is a 16-byte array
self.__bytes = array.array('B', b'\0' * self.ADDRESS_BYTE_SIZE)
self.__scope_id = ""
#Invoke a constructor based on the type of the argument
if isinstance(address, string_types):
self.__from_string(address)
else:
self.__from_bytes(address)
def __from_string(self, address):
#Separate the Scope ID, if present
if self.__is_a_scoped_address(address):
split_parts = address.split(self.SCOPE_SEPARATOR)
address = split_parts[0]
if split_parts[1] == "":
raise Exception("Empty scope ID")
self.__scope_id = split_parts[1]
#Expand address if it's in compressed form
if self.__is_address_in_compressed_form(address):
address = self.__expand_compressed_address(address)
#Insert leading zeroes where needed
address = self.__insert_leading_zeroes(address)
#Sanity check
if len(address) != self.ADDRESS_TEXT_SIZE:
raise Exception('IP6_Address - from_string - address size != ' + str(self.ADDRESS_TEXT_SIZE))
#Split address into hex groups
hex_groups = address.split(self.SEPARATOR)
if len(hex_groups) != self.TOTAL_HEX_GROUPS:
raise Exception('IP6_Address - parsed hex groups != ' + str(self.TOTAL_HEX_GROUPS))
#For each hex group, convert it into integer words
offset = 0
for group in hex_groups:
if len(group) != self.HEX_GROUP_SIZE:
raise Exception('IP6_Address - parsed hex group length != ' + str(self.HEX_GROUP_SIZE))
group_as_int = int(group, 16)
self.__bytes[offset] = (group_as_int & 0xFF00) >> 8
self.__bytes[offset + 1] = (group_as_int & 0x00FF)
offset += 2
def __from_bytes(self, theBytes):
if len(theBytes) != self.ADDRESS_BYTE_SIZE:
raise Exception ("IP6_Address - from_bytes - array size != " + str(self.ADDRESS_BYTE_SIZE))
self.__bytes = theBytes
#############################################################################################################
# Projectors
def as_string(self, compress_address = True, scoped_address = True):
s = ""
for i, v in enumerate(self.__bytes):
s += hex(v)[2:].rjust(2, '0')
if i % 2 == 1:
s += self.SEPARATOR
s = s[:-1].upper()
if compress_address:
s = self.__trim_leading_zeroes(s)
s = self.__trim_longest_zero_chain(s)
if scoped_address and self.get_scope_id() != "":
s += self.SCOPE_SEPARATOR + self.__scope_id
return s
def as_bytes(self):
return self.__bytes
def __str__(self):
return self.as_string()
def get_scope_id(self):
return self.__scope_id
def get_unscoped_address(self):
return self.as_string(True, False) #Compressed address = True, Scoped address = False
#############################################################################################################
# Semantic helpers
def is_multicast(self):
return self.__bytes[0] == 0xFF
def is_unicast(self):
return self.__bytes[0] == 0xFE
def is_link_local_unicast(self):
return self.is_unicast() and (self.__bytes[1] & 0xC0 == 0x80)
def is_site_local_unicast(self):
return self.is_unicast() and (self.__bytes[1] & 0xC0 == 0xC0)
def is_unique_local_unicast(self):
return self.__bytes[0] == 0xFD
def get_human_readable_address_type(self):
if self.is_multicast():
return "multicast"
elif self.is_unicast():
if self.is_link_local_unicast():
return "link-local unicast"
elif self.is_site_local_unicast():
return "site-local unicast"
else:
return "unicast"
elif self.is_unique_local_unicast():
return "unique-local unicast"
else:
return "unknown type"
#############################################################################################################
#Expansion helpers
#Predicate - returns whether an address is in compressed form
def __is_address_in_compressed_form(self, address):
#Sanity check - triple colon detection (not detected by searches of double colon)
if address.count(self.SEPARATOR * 3) > 0:
raise Exception('IP6_Address - found triple colon')
#Count the double colon marker
compression_marker_count = self.__count_compression_marker(address)
if compression_marker_count == 0:
return False
elif compression_marker_count == 1:
return True
else:
raise Exception('IP6_Address - more than one compression marker (\"::\") found')
#Returns how many hex groups are present, in a compressed address
def __count_compressed_groups(self, address):
trimmed_address = address.replace(self.SEPARATOR * 2, self.SEPARATOR) #Replace "::" with ":"
return trimmed_address.count(self.SEPARATOR) + 1
#Counts how many compression markers are present
def __count_compression_marker(self, address):
return address.count(self.SEPARATOR * 2) #Count occurrences of "::"
#Inserts leading zeroes in every hex group
def __insert_leading_zeroes(self, address):
hex_groups = address.split(self.SEPARATOR)
new_address = ""
for hex_group in hex_groups:
if len(hex_group) < 4:
hex_group = hex_group.rjust(4, "0")
new_address += hex_group + self.SEPARATOR
return new_address[:-1] #Trim the last colon
#Expands a compressed address
def __expand_compressed_address(self, address):
group_count = self.__count_compressed_groups(address)
groups_to_insert = self.TOTAL_HEX_GROUPS - group_count
pos = address.find(self.SEPARATOR * 2) + 1
while groups_to_insert:
address = address[:pos] + "0000" + self.SEPARATOR + address[pos:]
pos += 5
groups_to_insert -= 1
#Replace the compression marker with a single colon
address = address.replace(self.SEPARATOR * 2, self.SEPARATOR)
return address
#############################################################################################################
#Compression helpers
def __trim_longest_zero_chain(self, address):
chain_size = 8
while chain_size > 0:
groups = address.split(self.SEPARATOR)
for index, group in enumerate(groups):
#Find the first zero
if group == "0":
start_index = index
end_index = index
#Find the end of this chain of zeroes
while end_index < 7 and groups[end_index + 1] == "0":
end_index += 1
#If the zero chain matches the current size, trim it
found_size = end_index - start_index + 1
if found_size == chain_size:
address = self.SEPARATOR.join(groups[0:start_index]) + self.SEPARATOR * 2 + self.SEPARATOR.join(groups[(end_index+1):])
return address
#No chain of this size found, try with a lower size
chain_size -= 1
return address
#Trims all leading zeroes from every hex group
def __trim_leading_zeroes(self, theStr):
groups = theStr.split(self.SEPARATOR)
theStr = ""
for group in groups:
group = group.lstrip("0") + self.SEPARATOR
if group == self.SEPARATOR:
group = "0" + self.SEPARATOR
theStr += group
return theStr[:-1]
#############################################################################################################
@classmethod
def is_a_valid_text_representation(cls, text_representation):
try:
#Capitalize on the constructor's ability to detect invalid text representations of an IP6 address
IP6_Address(text_representation)
return True
except Exception:
return False
def __is_a_scoped_address(self, text_representation):
return text_representation.count(self.SCOPE_SEPARATOR) == 1