1# Copyright (C) 2003-2007, 2009 Nominum, Inc.
2#
3# Permission to use, copy, modify, and distribute this software and its
4# documentation for any purpose with or without fee is hereby granted,
5# provided that the above copyright notice and this permission notice
6# appear in all copies.
7#
8# THE SOFTWARE IS PROVIDED "AS IS" AND NOMINUM DISCLAIMS ALL WARRANTIES
9# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NOMINUM BE LIABLE FOR
11# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
14# OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15
16"""Common DNSSEC-related functions and constants."""
17
18RSAMD5 = 1
19DH = 2
20DSA = 3
21ECC = 4
22RSASHA1 = 5
23DSANSEC3SHA1 = 6
24RSASHA1NSEC3SHA1 = 7
25RSASHA256 = 8
26RSASHA512 = 10
27INDIRECT = 252
28PRIVATEDNS = 253
29PRIVATEOID = 254
30
31_algorithm_by_text = {
32    'RSAMD5' : RSAMD5,
33    'DH' : DH,
34    'DSA' : DSA,
35    'ECC' : ECC,
36    'RSASHA1' : RSASHA1,
37    'DSANSEC3SHA1' : DSANSEC3SHA1,
38    'RSASHA1NSEC3SHA1' : RSASHA1NSEC3SHA1,
39    'RSASHA256' : RSASHA256,
40    'RSASHA512' : RSASHA512,
41    'INDIRECT' : INDIRECT,
42    'PRIVATEDNS' : PRIVATEDNS,
43    'PRIVATEOID' : PRIVATEOID,
44    }
45
46# We construct the inverse mapping programmatically to ensure that we
47# cannot make any mistakes (e.g. omissions, cut-and-paste errors) that
48# would cause the mapping not to be true inverse.
49
50_algorithm_by_value = dict([(y, x) for x, y in _algorithm_by_text.iteritems()])
51
52class UnknownAlgorithm(Exception):
53    """Raised if an algorithm is unknown."""
54    pass
55
56def algorithm_from_text(text):
57    """Convert text into a DNSSEC algorithm value
58    @rtype: int"""
59
60    value = _algorithm_by_text.get(text.upper())
61    if value is None:
62        value = int(text)
63    return value
64
65def algorithm_to_text(value):
66    """Convert a DNSSEC algorithm value to text
67    @rtype: string"""
68
69    text = _algorithm_by_value.get(value)
70    if text is None:
71        text = str(value)
72    return text
73