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"""DNS Reverse Map Names.""" |
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import binascii |
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import dns.ipv4 |
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import dns.ipv6 |
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import dns.name |
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ipv4_reverse_domain = dns.name.from_text("in-addr.arpa.") |
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ipv6_reverse_domain = dns.name.from_text("ip6.arpa.") |
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def from_address( |
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text: str, |
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v4_origin: dns.name.Name = ipv4_reverse_domain, |
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v6_origin: dns.name.Name = ipv6_reverse_domain, |
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) -> dns.name.Name: |
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"""Convert an IPv4 or IPv6 address in textual form into a Name object whose |
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value is the reverse-map domain name of the address. |
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*text*, a ``str``, is an IPv4 or IPv6 address in textual form |
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(e.g. '127.0.0.1', '::1') |
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*v4_origin*, a ``dns.name.Name`` to append to the labels corresponding to |
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the address if the address is an IPv4 address, instead of the default |
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(in-addr.arpa.) |
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*v6_origin*, a ``dns.name.Name`` to append to the labels corresponding to |
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the address if the address is an IPv6 address, instead of the default |
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(ip6.arpa.) |
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Raises ``dns.exception.SyntaxError`` if the address is badly formed. |
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Returns a ``dns.name.Name``. |
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""" |
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try: |
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v6 = dns.ipv6.inet_aton(text) |
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if dns.ipv6.is_mapped(v6): |
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parts = ["%d" % byte for byte in v6[12:]] |
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origin = v4_origin |
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else: |
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parts = [x for x in str(binascii.hexlify(v6).decode())] |
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origin = v6_origin |
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except Exception: |
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parts = ["%d" % byte for byte in dns.ipv4.inet_aton(text)] |
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origin = v4_origin |
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return dns.name.from_text(".".join(reversed(parts)), origin=origin) |
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def to_address( |
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name: dns.name.Name, |
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v4_origin: dns.name.Name = ipv4_reverse_domain, |
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v6_origin: dns.name.Name = ipv6_reverse_domain, |
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) -> str: |
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"""Convert a reverse map domain name into textual address form. |
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*name*, a ``dns.name.Name``, an IPv4 or IPv6 address in reverse-map name |
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form. |
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*v4_origin*, a ``dns.name.Name`` representing the top-level domain for |
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IPv4 addresses, instead of the default (in-addr.arpa.) |
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*v6_origin*, a ``dns.name.Name`` representing the top-level domain for |
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IPv4 addresses, instead of the default (ip6.arpa.) |
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Raises ``dns.exception.SyntaxError`` if the name does not have a |
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reverse-map form. |
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Returns a ``str``. |
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""" |
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if name.is_subdomain(v4_origin): |
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name = name.relativize(v4_origin) |
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text = b".".join(reversed(name.labels)) |
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return dns.ipv4.inet_ntoa(dns.ipv4.inet_aton(text)) |
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elif name.is_subdomain(v6_origin): |
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name = name.relativize(v6_origin) |
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labels = list(reversed(name.labels)) |
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parts = [] |
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for i in range(0, len(labels), 4): |
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parts.append(b"".join(labels[i : i + 4])) |
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text = b":".join(parts) |
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return dns.ipv6.inet_ntoa(dns.ipv6.inet_aton(text)) |
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else: |
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raise dns.exception.SyntaxError("unknown reverse-map address family") |
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