# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license
# Copyright (C) 2006-2017 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.
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# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NOMINUM BE LIABLE FOR
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"""DNS Reverse Map Names."""
import binascii
import dns.exception
import dns.ipv4
import dns.ipv6
import dns.name
ipv4_reverse_domain = dns.name.from_text("in-addr.arpa.")
ipv6_reverse_domain = dns.name.from_text("ip6.arpa.")
[docs]
def from_address(
text: str,
v4_origin: dns.name.Name = ipv4_reverse_domain,
v6_origin: dns.name.Name = ipv6_reverse_domain,
) -> dns.name.Name:
"""Convert an IPv4 or IPv6 address in textual form into a Name object whose
value is the reverse-map domain name of the address.
:param text: An IPv4 or IPv6 address in textual form (e.g. ``'127.0.0.1'``,
``'::1'``).
:type text: str
:param v4_origin: Domain to append for IPv4 addresses instead of
``in-addr.arpa.``
:type v4_origin: :py:class:`dns.name.Name`
:param v6_origin: Domain to append for IPv6 addresses instead of
``ip6.arpa.``
:type v6_origin: :py:class:`dns.name.Name`
:raises dns.exception.SyntaxError: If the address is badly formed.
:rtype: :py:class:`dns.name.Name`
"""
try:
v6 = dns.ipv6.inet_aton(text)
if dns.ipv6.is_mapped(v6):
parts = [str(byte) for byte in v6[12:]]
origin = v4_origin
else:
parts = [x for x in str(binascii.hexlify(v6).decode())]
origin = v6_origin
except Exception:
parts = [str(byte) for byte in dns.ipv4.inet_aton(text)]
origin = v4_origin
return dns.name.from_text(".".join(reversed(parts)), origin=origin)
[docs]
def to_address(
name: dns.name.Name,
v4_origin: dns.name.Name = ipv4_reverse_domain,
v6_origin: dns.name.Name = ipv6_reverse_domain,
) -> str:
"""Convert a reverse map domain name into textual address form.
:param name: An IPv4 or IPv6 address in reverse-map name form.
:type name: :py:class:`dns.name.Name`
:param v4_origin: Top-level domain for IPv4 addresses (default
``in-addr.arpa.``).
:type v4_origin: :py:class:`dns.name.Name`
:param v6_origin: Top-level domain for IPv6 addresses (default
``ip6.arpa.``).
:type v6_origin: :py:class:`dns.name.Name`
:raises dns.exception.SyntaxError: If the name does not have a
reverse-map form.
:rtype: str
"""
if name.is_subdomain(v4_origin):
name = name.relativize(v4_origin)
text = b".".join(reversed(name.labels))
# run through inet_ntoa() to check syntax and make pretty.
return dns.ipv4.inet_ntoa(dns.ipv4.inet_aton(text))
elif name.is_subdomain(v6_origin):
name = name.relativize(v6_origin)
labels = list(reversed(name.labels))
parts = []
for i in range(0, len(labels), 4):
parts.append(b"".join(labels[i : i + 4]))
text = b":".join(parts)
# run through inet_ntoa() to check syntax and make pretty.
return dns.ipv6.inet_ntoa(dns.ipv6.inet_aton(text))
else:
raise dns.exception.SyntaxError("unknown reverse-map address family")