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- # 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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