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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
46
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48
49
50 _by_value = dict([(y, x) for x, y in _by_text.iteritems()])
51
52
53
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
69 """Raised when a class is unknown."""
70 pass
71
73 """Convert text into a DNS rdata class value.
74 @param text: the text
75 @type text: string
76 @rtype: int
77 @raises dns.rdataclass.UnknownRdataclass: the class is unknown
78 @raises ValueError: the rdata class value is not >= 0 and <= 65535
79 """
80
81 value = _by_text.get(text.upper())
82 if value is None:
83 match = _unknown_class_pattern.match(text)
84 if match == None:
85 raise UnknownRdataclass
86 value = int(match.group(1))
87 if value < 0 or value > 65535:
88 raise ValueError("class must be between >= 0 and <= 65535")
89 return value
90
92 """Convert a DNS rdata class to text.
93 @param value: the rdata class value
94 @type value: int
95 @rtype: string
96 @raises ValueError: the rdata class value is not >= 0 and <= 65535
97 """
98
99 if value < 0 or value > 65535:
100 raise ValueError("class must be between >= 0 and <= 65535")
101 text = _by_value.get(value)
102 if text is None:
103 text = 'CLASS' + `value`
104 return text
105
115