Package dns :: Package rdtypes :: Package ANY :: Module NSEC |
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# Source Code for Module dns.rdtypes.ANY.NSEC

      1  # Copyright (C) 2004-2007, 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  import cStringIO
     17
     18  import dns.exception
     19  import dns.rdata
     20  import dns.rdatatype
     21  import dns.name
     22
     23 -class NSEC(dns.rdata.Rdata):
     24      """NSEC record
     25
     26      @ivar next: the next name
     27      @type next: dns.name.Name object
     28      @ivar windows: the windowed bitmap list
     29      @type windows: list of (window number, string) tuples"""
     30
     31      __slots__ = ['next', 'windows']
     32
     33 -    def __init__(self, rdclass, rdtype, next, windows):
     34          super(NSEC, self).__init__(rdclass, rdtype)
     35          self.next = next
     36          self.windows = windows
     37
     38 -    def to_text(self, origin=None, relativize=True, **kw):
     39          next = self.next.choose_relativity(origin, relativize)
     40          text = ''
     41          for (window, bitmap) in self.windows:
     42              bits = []
     43              for i in xrange(0, len(bitmap)):
     44                  byte = ord(bitmap[i])
     45                  for j in xrange(0, 8):
     46                      if byte & (0x80 >> j):
     47                          bits.append(dns.rdatatype.to_text(window * 256 + \
     48                                                            i * 8 + j))
     49              text += (' ' + ' '.join(bits))
     50          return '%s%s' % (next, text)
     51
     52 -    def from_text(cls, rdclass, rdtype, tok, origin = None, relativize = True):
     53          next = tok.get_name()
     54          next = next.choose_relativity(origin, relativize)
     55          rdtypes = []
     56          while 1:
     57              token = tok.get().unescape()
     58              if token.is_eol_or_eof():
     59                  break
     60              nrdtype = dns.rdatatype.from_text(token.value)
     61              if nrdtype == 0:
     62                  raise dns.exception.SyntaxError("NSEC with bit 0")
     63              if nrdtype > 65535:
     64                  raise dns.exception.SyntaxError("NSEC with bit > 65535")
     65              rdtypes.append(nrdtype)
     66          rdtypes.sort()
     67          window = 0
     68          octets = 0
     69          prior_rdtype = 0
     70          bitmap = ['\0'] * 32
     71          windows = []
     72          for nrdtype in rdtypes:
     73              if nrdtype == prior_rdtype:
     74                  continue
     75              prior_rdtype = nrdtype
     76              new_window = nrdtype // 256
     77              if new_window != window:
     78                  windows.append((window, ''.join(bitmap[0:octets])))
     79                  bitmap = ['\0'] * 32
     80                  window = new_window
     81              offset = nrdtype % 256
     82              byte = offset / 8
     83              bit = offset % 8
     84              octets = byte + 1
     85              bitmap[byte] = chr(ord(bitmap[byte]) | (0x80 >> bit))
     86          windows.append((window, ''.join(bitmap[0:octets])))
     87          return cls(rdclass, rdtype, next, windows)
     88
     89      from_text = classmethod(from_text)
     90
     91 -    def to_wire(self, file, compress = None, origin = None):
     92          self.next.to_wire(file, None, origin)
     93          for (window, bitmap) in self.windows:
     94              file.write(chr(window))
     95              file.write(chr(len(bitmap)))
     96              file.write(bitmap)
     97
     98 -    def from_wire(cls, rdclass, rdtype, wire, current, rdlen, origin = None):
     99          (next, cused) = dns.name.from_wire(wire[: current + rdlen], current)
    100          current += cused
    101          rdlen -= cused
    102          windows = []
    103          while rdlen > 0:
    104              if rdlen < 3:
    105                  raise dns.exception.FormError("NSEC too short")
    106              window = ord(wire[current])
    107              octets = ord(wire[current + 1])
    108              if octets == 0 or octets > 32:
    109                  raise dns.exception.FormError("bad NSEC octets")
    110              current += 2
    111              rdlen -= 2
    112              if rdlen < octets:
    113                  raise dns.exception.FormError("bad NSEC bitmap length")
    114              bitmap = wire[current : current + octets]
    115              current += octets
    116              rdlen -= octets
    117              windows.append((window, bitmap))
    118          if not origin is None:
    119              next = next.relativize(origin)
    120          return cls(rdclass, rdtype, next, windows)
    121
    122      from_wire = classmethod(from_wire)
    123
    124 -    def choose_relativity(self, origin = None, relativize = True):
    125          self.next = self.next.choose_relativity(origin, relativize)
    126
    127 -    def _cmp(self, other):
    128          return self._wire_cmp(other)
    129