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1 # Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license
2
3 # Copyright (C) 2001-2017 Nominum, Inc.
4 #
5 # Permission to use, copy, modify, and distribute this software and its
6 # documentation for any purpose with or without fee is hereby granted,
7 # provided that the above copyright notice and this permission notice
8 # appear in all copies.
9 #
10 # THE SOFTWARE IS PROVIDED "AS IS" AND NOMINUM DISCLAIMS ALL WARRANTIES
11 # WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 # MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NOMINUM BE LIABLE FOR
13 # ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 # WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 # ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
16 # OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17
18 """DNS Opcodes."""
19
20 import dns.exception
21
22 #: Query
23 QUERY = 0
24 #: Inverse Query (historical)
25 IQUERY = 1
26 #: Server Status (unspecified and unimplemented anywhere)
27 STATUS = 2
28 #: Notify
29 NOTIFY = 4
30 #: Dynamic Update
31 UPDATE = 5
32
33 _by_text = {
34 'QUERY': QUERY,
35 'IQUERY': IQUERY,
36 'STATUS': STATUS,
37 'NOTIFY': NOTIFY,
38 'UPDATE': UPDATE
39 }
40
41 # We construct the inverse mapping programmatically to ensure that we
42 # cannot make any mistakes (e.g. omissions, cut-and-paste errors) that
43 # would cause the mapping not to be true inverse.
44
45 _by_value = {y: x for x, y in _by_text.items()}
46
47
50
51
53 """Convert text into an opcode.
54
55 *text*, a ``text``, the textual opcode
56
57 Raises ``dns.opcode.UnknownOpcode`` if the opcode is unknown.
58
59 Returns an ``int``.
60 """
61
62 if text.isdigit():
63 value = int(text)
64 if value >= 0 and value <= 15:
65 return value
66 value = _by_text.get(text.upper())
67 if value is None:
68 raise UnknownOpcode
69 return value
70
71
73 """Extract an opcode from DNS message flags.
74
75 *flags*, an ``int``, the DNS flags.
76
77 Returns an ``int``.
78 """
79
80 return (flags & 0x7800) >> 11
81
82
84 """Convert an opcode to a value suitable for ORing into DNS message
85 flags.
86
87 *value*, an ``int``, the DNS opcode value.
88
89 Returns an ``int``.
90 """
91
92 return (value << 11) & 0x7800
93
94
96 """Convert an opcode to text.
97
98 *value*, an ``int`` the opcode value,
99
100 Raises ``dns.opcode.UnknownOpcode`` if the opcode is unknown.
101
102 Returns a ``text``.
103 """
104
105 text = _by_value.get(value)
106 if text is None:
107 text = str(value)
108 return text
109
110
112 """Is the opcode in flags UPDATE?
113
114 *flags*, an ``int``, the DNS message flags.
115
116 Returns a ``bool``.
117 """
118
119 return from_flags(flags) == UPDATE
120
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