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, 2009-2011 Nominum, Inc. 
  2  # 
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  4  # documentation for any purpose with or without fee is hereby granted, 
  5  # provided that the above copyright notice and this permission notice 
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 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].unwrap() 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):
126
127 - def _cmp(self, other):
128 return self._wire_cmp(other)
129