# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license
# Copyright (C) 2003-2017 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 binascii
import re
from typing import List, Union
import dns.exception
import dns.ipv4
_leading_zero = re.compile(r"0+([0-9a-f]+)")
[docs]
def inet_ntoa(address: bytes) -> str:
"""Convert an IPv6 address in binary form to text form.
*address*, a ``bytes``, the IPv6 address in binary form.
Raises ``ValueError`` if the address isn't 16 bytes long.
Returns a ``str``.
"""
if len(address) != 16:
raise ValueError("IPv6 addresses are 16 bytes long")
hex = binascii.hexlify(address)
chunks = []
i = 0
l = len(hex)
while i < l:
chunk = hex[i : i + 4].decode()
# 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 m is not 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 range(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:"
thex = prefix + dns.ipv4.inet_ntoa(address[12:])
else:
thex = (
":".join(chunks[:best_start])
+ "::"
+ ":".join(chunks[best_start + best_len :])
)
else:
thex = ":".join(chunks)
return thex
_v4_ending = re.compile(rb"(.*):(\d+\.\d+\.\d+\.\d+)$")
_colon_colon_start = re.compile(rb"::.*")
_colon_colon_end = re.compile(rb".*::$")
[docs]
def inet_aton(text: Union[str, bytes], ignore_scope: bool = False) -> bytes:
"""Convert an IPv6 address in text form to binary form.
*text*, a ``str`` or ``bytes``, the IPv6 address in textual form.
*ignore_scope*, a ``bool``. If ``True``, a scope will be ignored.
If ``False``, the default, it is an error for a scope to be present.
Returns a ``bytes``.
"""
#
# Our aim here is not something fast; we just want something that works.
#
if not isinstance(text, bytes):
btext = text.encode()
else:
btext = text
if ignore_scope:
parts = btext.split(b"%")
l = len(parts)
if l == 2:
btext = parts[0]
elif l > 2:
raise dns.exception.SyntaxError
if btext == b"":
raise dns.exception.SyntaxError
elif btext.endswith(b":") and not btext.endswith(b"::"):
raise dns.exception.SyntaxError
elif btext.startswith(b":") and not btext.startswith(b"::"):
raise dns.exception.SyntaxError
elif btext == b"::":
btext = b"0::"
#
# Get rid of the icky dot-quad syntax if we have it.
#
m = _v4_ending.match(btext)
if m is not None:
b = dns.ipv4.inet_aton(m.group(2))
btext = (
"{}:{:02x}{:02x}:{:02x}{:02x}".format(
m.group(1).decode(), b[0], b[1], b[2], b[3]
)
).encode()
#
# Try to turn '::<whatever>' into ':<whatever>'; if no match try to
# turn '<whatever>::' into '<whatever>:'
#
m = _colon_colon_start.match(btext)
if m is not None:
btext = btext[1:]
else:
m = _colon_colon_end.match(btext)
if m is not None:
btext = btext[:-1]
#
# Now canonicalize into 8 chunks of 4 hex digits each
#
chunks = btext.split(b":")
l = len(chunks)
if l > 8:
raise dns.exception.SyntaxError
seen_empty = False
canonical: List[bytes] = []
for c in chunks:
if c == b"":
if seen_empty:
raise dns.exception.SyntaxError
seen_empty = True
for _ in range(0, 8 - l + 1):
canonical.append(b"0000")
else:
lc = len(c)
if lc > 4:
raise dns.exception.SyntaxError
if lc != 4:
c = (b"0" * (4 - lc)) + c
canonical.append(c)
if l < 8 and not seen_empty:
raise dns.exception.SyntaxError
btext = b"".join(canonical)
#
# Finally we can go to binary.
#
try:
return binascii.unhexlify(btext)
except (binascii.Error, TypeError):
raise dns.exception.SyntaxError
_mapped_prefix = b"\x00" * 10 + b"\xff\xff"
[docs]
def is_mapped(address: bytes) -> bool:
"""Is the specified address a mapped IPv4 address?
*address*, a ``bytes`` is an IPv6 address in binary form.
Returns a ``bool``.
"""
return address.startswith(_mapped_prefix)
[docs]
def canonicalize(text: Union[str, bytes]) -> str:
"""Verify that *address* is a valid text form IPv6 address and return its
canonical text form. Addresses with scopes are rejected.
*text*, a ``str`` or ``bytes``, the IPv6 address in textual form.
Raises ``dns.exception.SyntaxError`` if the text is not valid.
"""
return dns.ipv6.inet_ntoa(dns.ipv6.inet_aton(text))