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Editing: ipv6.py
# 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]+)") 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+)$") _colon_colon_start = re.compile(rb"::.*") _colon_colon_end = re.compile(rb".*::$") 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 = ( f"{m.group(1).decode()}:{b[0]:02x}{b[1]:02x}:{b[2]:02x}{b[3]:02x}" ).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" 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) 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))
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