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EDIT :: rdataclass.py

# Copyright (C) 2001-2007, 2009-2011 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. """DNS Rdata Classes. @var _by_text: The rdata class textual name to value mapping @type _by_text: dict @var _by_value: The rdata class value to textual name mapping @type _by_value: dict @var _metaclasses: If an rdataclass is a metaclass, there will be a mapping whose key is the rdatatype value and whose value is True in this dictionary. @type _metaclasses: dict""" import re import dns.exception RESERVED0 = 0 IN = 1 CH = 3 HS = 4 NONE = 254 ANY = 255 _by_text = { 'RESERVED0': RESERVED0, 'IN': IN, 'CH': CH, 'HS': HS, 'NONE': NONE, 'ANY': ANY } # We construct the inverse mapping programmatically to ensure that we # cannot make any mistakes (e.g. omissions, cut-and-paste errors) that # would cause the mapping not to be true inverse. _by_value = dict((y, x) for x, y in _by_text.items()) # Now that we've built the inverse map, we can add class aliases to # the _by_text mapping. _by_text.update({ 'INTERNET': IN, 'CHAOS': CH, 'HESIOD': HS }) _metaclasses = { NONE: True, ANY: True } _unknown_class_pattern = re.compile('CLASS([0-9]+)$', re.I) class UnknownRdataclass(dns.exception.DNSException): """A DNS class is unknown.""" def from_text(text): """Convert text into a DNS rdata class value. @param text: the text @type text: string @rtype: int @raises dns.rdataclass.UnknownRdataclass: the class is unknown @raises ValueError: the rdata class value is not >= 0 and <= 65535 """ value = _by_text.get(text.upper()) if value is None: match = _unknown_class_pattern.match(text) if match is None: raise UnknownRdataclass value = int(match.group(1)) if value < 0 or value > 65535: raise ValueError("class must be between >= 0 and <= 65535") return value def to_text(value): """Convert a DNS rdata class to text. @param value: the rdata class value @type value: int @rtype: string @raises ValueError: the rdata class value is not >= 0 and <= 65535 """ if value < 0 or value > 65535: raise ValueError("class must be between >= 0 and <= 65535") text = _by_value.get(value) if text is None: text = 'CLASS' + repr(value) return text def is_metaclass(rdclass): """True if the class is a metaclass. @param rdclass: the rdata class @type rdclass: int @rtype: bool""" if rdclass in _metaclasses: return True return False

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