1# Copyright (C) 2010 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
16import struct
17
18import dns.rdata
19import dns.rdatatype
20
21class DSBase(dns.rdata.Rdata):
22    """Base class for rdata that is like a DS record
23
24    @ivar key_tag: the key tag
25    @type key_tag: int
26    @ivar algorithm: the algorithm
27    @type algorithm: int
28    @ivar digest_type: the digest type
29    @type digest_type: int
30    @ivar digest: the digest
31    @type digest: int
32    @see: draft-ietf-dnsext-delegation-signer-14.txt"""
33
34    __slots__ = ['key_tag', 'algorithm', 'digest_type', 'digest']
35
36    def __init__(self, rdclass, rdtype, key_tag, algorithm, digest_type,
37                 digest):
38        super(DSBase, self).__init__(rdclass, rdtype)
39        self.key_tag = key_tag
40        self.algorithm = algorithm
41        self.digest_type = digest_type
42        self.digest = digest
43
44    def to_text(self, origin=None, relativize=True, **kw):
45        return '%d %d %d %s' % (self.key_tag, self.algorithm,
46                                self.digest_type,
47                                dns.rdata._hexify(self.digest,
48                                                  chunksize=128))
49
50    def from_text(cls, rdclass, rdtype, tok, origin = None, relativize = True):
51        key_tag = tok.get_uint16()
52        algorithm = tok.get_uint8()
53        digest_type = tok.get_uint8()
54        chunks = []
55        while 1:
56            t = tok.get().unescape()
57            if t.is_eol_or_eof():
58                break
59            if not t.is_identifier():
60                raise dns.exception.SyntaxError
61            chunks.append(t.value)
62        digest = ''.join(chunks)
63        digest = digest.decode('hex_codec')
64        return cls(rdclass, rdtype, key_tag, algorithm, digest_type,
65                   digest)
66
67    from_text = classmethod(from_text)
68
69    def to_wire(self, file, compress = None, origin = None):
70        header = struct.pack("!HBB", self.key_tag, self.algorithm,
71                             self.digest_type)
72        file.write(header)
73        file.write(self.digest)
74
75    def from_wire(cls, rdclass, rdtype, wire, current, rdlen, origin = None):
76        header = struct.unpack("!HBB", wire[current : current + 4])
77        current += 4
78        rdlen -= 4
79        digest = wire[current : current + rdlen]
80        return cls(rdclass, rdtype, header[0], header[1], header[2], digest)
81
82    from_wire = classmethod(from_wire)
83
84    def _cmp(self, other):
85        hs = struct.pack("!HBB", self.key_tag, self.algorithm,
86                         self.digest_type)
87        ho = struct.pack("!HBB", other.key_tag, other.algorithm,
88                         other.digest_type)
89        v = cmp(hs, ho)
90        if v == 0:
91            v = cmp(self.digest, other.digest)
92        return v
93