Package dns :: Package rdtypes :: Module dsbase |
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# Source Code for Module dns.rdtypes.dsbase

     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
    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]
    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