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75 lines
2.1 KiB
Python
75 lines
2.1 KiB
Python
import ipaddress
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import dns.name
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def reverse_zone(network):
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"""
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Reverse a network zone
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Takes an network object (`ipaddress.IPv4Network` or
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`ipaddress.IPv6Network`) as an input and returns a DNS name object
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(`dns.name.Name`) corresponding to the reverse DNS entry correctly
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formated.
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Parameters
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----------
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network: ipaddress.IPv4Network or ipaddress.IPv6Network
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The Network IP and mask object
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Return
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------
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reversed_zone: dns.name.Name
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The reverse zone as a DNS Name oject
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Examples
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--------
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>>> # Some IPv4 Networks
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>>> net1 = ipaddress.IPv4Network("10.128.12.0/24")
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>>> net2 = ipaddress.IPv4Network("10.129.0.0/16")
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>>> net3 = ipaddress.IPv4Network("10.0.0.0/8")
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>>> # Some IPv6 Networks
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>>> net4 = ipaddress.IPv6Network("2001:470:142:3::/64")
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>>> net5 = ipaddress.IPv6Network("2001:470:142::/48")
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>>> net6 = ipaddress.IPv6Network("2a09:6840::/32")
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>>> # And the expected outputs
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>>> reverse_zone(net1)
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'12.128.10.in-addr.arpa'
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>>> reverse_zone(net2)
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'129.10.in-addr.arpa'
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>>> reverse_zone(net3)
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'10.in-addr.arpa'
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>>> reverse_zone(net4)
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'3.0.0.0.2.4.1.0.0.7.4.0.1.0.0.2.ip6.arpa'
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>>> reverse_zone(net5)
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'2.4.1.0.0.7.4.0.1.0.0.2.ip6.arpa'
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>>> reverse_zone(net6)
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'0.4.8.6.9.0.a.2.ip6.arpa'
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See also
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--------
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dnspython: https://dnspython.readthedocs.io
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ipaddress: https://docs.python.org/3/library/ipaddress.html
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References
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----------
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[1] RFC 1035: DOMAIN NAMES - IMPLEMENTATION AND SPECIFICATION,
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IETF, Network Working Group, November 1987.
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"""
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if network.version == 4:
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boundary = 8 # break to the byte
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elif network.version == 6:
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boundary = 4 # break to the nibble
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assert network.prefixlen % boundary == 0
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length = (network.prefixlen // boundary)
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full_network_reverse = network.network_address.reverse_pointer
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splitted = full_network_reverse.split(".")
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splitting_len = int(network.max_prefixlen / boundary)
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splitted = splitted[splitting_len - length:]
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reversed_zone = ".".join(splitted)
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return dns.name.from_text(reversed_zone)
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