lib/dnspython/dns/rdtypes/dsbase.py

   1 # Copyright (C) 2010, 2011 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 import struct
  17
  18 import dns.rdata
  19 import dns.rdatatype
  20
  21 class 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].unwrap()
  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