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16 """DNS Rdata Classes.
17
18 @var _by_text: The rdata class textual name to value mapping
19 @type _by_text: dict
20 @var _by_value: The rdata class value to textual name mapping
21 @type _by_value: dict
22 @var _metaclasses: If an rdataclass is a metaclass, there will be a mapping
23 whose key is the rdatatype value and whose value is True in this dictionary.
24 @type _metaclasses: dict"""
25
26 import re
27
28 import dns.exception
29
30 RESERVED0 = 0
31 IN = 1
32 CH = 3
33 HS = 4
34 NONE = 254
35 ANY = 255
36
37 _by_text = {
38 'RESERVED0': RESERVED0,
39 'IN': IN,
40 'CH': CH,
41 'HS': HS,
42 'NONE': NONE,
43 'ANY': ANY
44 }
45
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48
49
50 _by_value = dict((y, x) for x, y in _by_text.items())
51
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54
55 _by_text.update({
56 'INTERNET': IN,
57 'CHAOS': CH,
58 'HESIOD': HS
59 })
60
61 _metaclasses = {
62 NONE: True,
63 ANY: True
64 }
65
66 _unknown_class_pattern = re.compile('CLASS([0-9]+)$', re.I)
67
68
70
71 """A DNS class is unknown."""
72
73
75 """Convert text into a DNS rdata class value.
76 @param text: the text
77 @type text: string
78 @rtype: int
79 @raises dns.rdataclass.UnknownRdataclass: the class is unknown
80 @raises ValueError: the rdata class value is not >= 0 and <= 65535
81 """
82
83 value = _by_text.get(text.upper())
84 if value is None:
85 match = _unknown_class_pattern.match(text)
86 if match is None:
87 raise UnknownRdataclass
88 value = int(match.group(1))
89 if value < 0 or value > 65535:
90 raise ValueError("class must be between >= 0 and <= 65535")
91 return value
92
93
95 """Convert a DNS rdata class to text.
96 @param value: the rdata class value
97 @type value: int
98 @rtype: string
99 @raises ValueError: the rdata class value is not >= 0 and <= 65535
100 """
101
102 if value < 0 or value > 65535:
103 raise ValueError("class must be between >= 0 and <= 65535")
104 text = _by_value.get(value)
105 if text is None:
106 text = 'CLASS' + repr(value)
107 return text
108
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