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# Copyright (C) 2003-2007, 2009-2011 Nominum, Inc.
#
# Permission to use, copy, modify, and distribute this software and its
# documentation for any purpose with or without fee is hereby granted,
# provided that the above copyright notice and this permission notice
# appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND NOMINUM DISCLAIMS ALL WARRANTIES
# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NOMINUM BE LIABLE FOR
# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
# OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
"""IPv6 helper functions."""
import re
import dns.exception
import dns.ipv4
_leading_zero = re.compile(r'0+([0-9a-f]+)')
def inet_ntoa(address):
"""Convert a network format IPv6 address into text.
@param address: the binary address
@type address: string
@rtype: string
@raises ValueError: the address isn't 16 bytes long
"""
if len(address) != 16:
raise ValueError("IPv6 addresses are 16 bytes long")
hex = address.encode('hex_codec')
chunks = []
i = 0
l = len(hex)
while i < l:
chunk = hex[i : i + 4]
# strip leading zeros. we do this with an re instead of
# with lstrip() because lstrip() didn't support chars until
# python 2.2.2
m = _leading_zero.match(chunk)
if not m is None:
chunk = m.group(1)
chunks.append(chunk)
i += 4
#
# Compress the longest subsequence of 0-value chunks to ::
#
best_start = 0
best_len = 0
start = -1
last_was_zero = False
for i in xrange(8):
if chunks[i] != '0':
if last_was_zero:
end = i
current_len = end - start
if current_len > best_len:
best_start = start
best_len = current_len
last_was_zero = False
elif not last_was_zero:
start = i
last_was_zero = True
if last_was_zero:
end = 8
current_len = end - start
if current_len > best_len:
best_start = start
best_len = current_len
if best_len > 1:
if best_start == 0 and \
(best_len == 6 or
best_len == 5 and chunks[5] == 'ffff'):
# We have an embedded IPv4 address
if best_len == 6:
prefix = '::'
else:
prefix = '::ffff:'
hex = prefix + dns.ipv4.inet_ntoa(address[12:])
else:
hex = ':'.join(chunks[:best_start]) + '::' + \
':'.join(chunks[best_start + best_len:])
else:
hex = ':'.join(chunks)
return hex
_v4_ending = re.compile(r'(.*):(\d+\.\d+\.\d+\.\d+)$')
_colon_colon_start = re.compile(r'::.*')
_colon_colon_end = re.compile(r'.*::$')
def inet_aton(text):
"""Convert a text format IPv6 address into network format.
@param text: the textual address
@type text: string
@rtype: string
@raises dns.exception.SyntaxError: the text was not properly formatted
"""
#
# Our aim here is not something fast; we just want something that works.
#
if text == '::':
text = '0::'
#
# Get rid of the icky dot-quad syntax if we have it.
#
m = _v4_ending.match(text)
if not m is None:
b = dns.ipv4.inet_aton(m.group(2))
text = "%s:%02x%02x:%02x%02x" % (m.group(1), ord(b[0]), ord(b[1]),
ord(b[2]), ord(b[3]))
#
# Try to turn '::<whatever>' into ':<whatever>'; if no match try to
# turn '<whatever>::' into '<whatever>:'
#
m = _colon_colon_start.match(text)
if not m is None:
text = text[1:]
else:
m = _colon_colon_end.match(text)
if not m is None:
text = text[:-1]
#
# Now canonicalize into 8 chunks of 4 hex digits each
#
chunks = text.split(':')
l = len(chunks)
if l > 8:
raise dns.exception.SyntaxError
seen_empty = False
canonical = []
for c in chunks:
if c == '':
if seen_empty:
raise dns.exception.SyntaxError
seen_empty = True
for i in xrange(0, 8 - l + 1):
canonical.append('0000')
else:
lc = len(c)
if lc > 4:
raise dns.exception.SyntaxError
if lc != 4:
c = ('0' * (4 - lc)) + c
canonical.append(c)
if l < 8 and not seen_empty:
raise dns.exception.SyntaxError
text = ''.join(canonical)
#
# Finally we can go to binary.
#
try:
return text.decode('hex_codec')
except TypeError:
raise dns.exception.SyntaxError
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