1# Copyright (C) 2003-2007, 2009, 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
16"""DNS name dictionary"""
17
18import dns.name
19
20class NameDict(dict):
21
22    """A dictionary whose keys are dns.name.Name objects.
23    @ivar max_depth: the maximum depth of the keys that have ever been
24    added to the dictionary.
25    @type max_depth: int
26    """
27
28    def __init__(self, *args, **kwargs):
29        super(NameDict, self).__init__(*args, **kwargs)
30        self.max_depth = 0
31
32    def __setitem__(self, key, value):
33        if not isinstance(key, dns.name.Name):
34            raise ValueError('NameDict key must be a name')
35        depth = len(key)
36        if depth > self.max_depth:
37            self.max_depth = depth
38        super(NameDict, self).__setitem__(key, value)
39
40    def get_deepest_match(self, name):
41        """Find the deepest match to I{name} in the dictionary.
42
43        The deepest match is the longest name in the dictionary which is
44        a superdomain of I{name}.
45
46        @param name: the name
47        @type name: dns.name.Name object
48        @rtype: (key, value) tuple
49        """
50
51        depth = len(name)
52        if depth > self.max_depth:
53            depth = self.max_depth
54        for i in xrange(-depth, 0):
55            n = dns.name.Name(name[i:])
56            if self.has_key(n):
57                return (n, self[n])
58        v = self[dns.name.empty]
59        return (dns.name.empty, v)
60