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16 """DNS rdata.
17
18 @var _rdata_modules: A dictionary mapping a (rdclass, rdtype) tuple to
19 the module which implements that type.
20 @type _rdata_modules: dict
21 @var _module_prefix: The prefix to use when forming modules names. The
22 default is 'dns.rdtypes'. Changing this value will break the library.
23 @type _module_prefix: string
24 @var _hex_chunk: At most this many octets that will be represented in each
25 chunk of hexstring that _hexify() produces before whitespace occurs.
26 @type _hex_chunk: int"""
27
28 import cStringIO
29
30 import dns.exception
31 import dns.rdataclass
32 import dns.rdatatype
33 import dns.tokenizer
34
35 _hex_chunksize = 32
36
38 """Convert a binary string into its hex encoding, broken up into chunks
39 of I{chunksize} characters separated by a space.
40
41 @param data: the binary string
42 @type data: string
43 @param chunksize: the chunk size. Default is L{dns.rdata._hex_chunksize}
44 @rtype: string
45 """
46
47 if chunksize is None:
48 chunksize = _hex_chunksize
49 hex = data.encode('hex_codec')
50 l = len(hex)
51 if l > chunksize:
52 chunks = []
53 i = 0
54 while i < l:
55 chunks.append(hex[i : i + chunksize])
56 i += chunksize
57 hex = ' '.join(chunks)
58 return hex
59
60 _base64_chunksize = 32
61
63 """Convert a binary string into its base64 encoding, broken up into chunks
64 of I{chunksize} characters separated by a space.
65
66 @param data: the binary string
67 @type data: string
68 @param chunksize: the chunk size. Default is
69 L{dns.rdata._base64_chunksize}
70 @rtype: string
71 """
72
73 if chunksize is None:
74 chunksize = _base64_chunksize
75 b64 = data.encode('base64_codec')
76 b64 = b64.replace('\n', '')
77 l = len(b64)
78 if l > chunksize:
79 chunks = []
80 i = 0
81 while i < l:
82 chunks.append(b64[i : i + chunksize])
83 i += chunksize
84 b64 = ' '.join(chunks)
85 return b64
86
87 __escaped = {
88 '"' : True,
89 '\\' : True,
90 }
91
93 """Escape the characters in a quoted string which need it.
94
95 @param qstring: the string
96 @type qstring: string
97 @returns: the escaped string
98 @rtype: string
99 """
100
101 text = ''
102 for c in qstring:
103 if c in __escaped:
104 text += '\\' + c
105 elif ord(c) >= 0x20 and ord(c) < 0x7F:
106 text += c
107 else:
108 text += '\\%03d' % ord(c)
109 return text
110
112 """Determine the index of greatest byte that isn't all zeros, and
113 return the bitmap that contains all the bytes less than that index.
114
115 @param what: a string of octets representing a bitmap.
116 @type what: string
117 @rtype: string
118 """
119
120 for i in xrange(len(what) - 1, -1, -1):
121 if what[i] != '\x00':
122 break
123 return ''.join(what[0 : i + 1])
124
126 """Base class for all DNS rdata types.
127 """
128
129 __slots__ = ['rdclass', 'rdtype']
130
132 """Initialize an rdata.
133 @param rdclass: The rdata class
134 @type rdclass: int
135 @param rdtype: The rdata type
136 @type rdtype: int
137 """
138
139 self.rdclass = rdclass
140 self.rdtype = rdtype
141
143 """DNS SIG/RRSIG rdatas apply to a specific type; this type is
144 returned by the covers() function. If the rdata type is not
145 SIG or RRSIG, dns.rdatatype.NONE is returned. This is useful when
146 creating rdatasets, allowing the rdataset to contain only RRSIGs
147 of a particular type, e.g. RRSIG(NS).
148 @rtype: int
149 """
150
151 return dns.rdatatype.NONE
152
154 """Return a 32-bit type value, the least significant 16 bits of
155 which are the ordinary DNS type, and the upper 16 bits of which are
156 the "covered" type, if any.
157 @rtype: int
158 """
159
160 return self.covers() << 16 | self.rdtype
161
162 - def to_text(self, origin=None, relativize=True, **kw):
163 """Convert an rdata to text format.
164 @rtype: string
165 """
166 raise NotImplementedError
167
168 - def to_wire(self, file, compress = None, origin = None):
169 """Convert an rdata to wire format.
170 @rtype: string
171 """
172
173 raise NotImplementedError
174
176 """Convert rdata to a format suitable for digesting in hashes. This
177 is also the DNSSEC canonical form."""
178 f = cStringIO.StringIO()
179 self.to_wire(f, None, origin)
180 return f.getvalue()
181
183 """Check that the current contents of the rdata's fields are
184 valid. If you change an rdata by assigning to its fields,
185 it is a good idea to call validate() when you are done making
186 changes.
187 """
188 dns.rdata.from_text(self.rdclass, self.rdtype, self.to_text())
189
199
202
203 - def _cmp(self, other):
204 """Compare an rdata with another rdata of the same rdtype and
205 rdclass. Return < 0 if self < other in the DNSSEC ordering,
206 0 if self == other, and > 0 if self > other.
207 """
208
209 raise NotImplementedError
210
212 if not isinstance(other, Rdata):
213 return False
214 if self.rdclass != other.rdclass or \
215 self.rdtype != other.rdtype:
216 return False
217 return self._cmp(other) == 0
218
220 if not isinstance(other, Rdata):
221 return True
222 if self.rdclass != other.rdclass or \
223 self.rdtype != other.rdtype:
224 return True
225 return self._cmp(other) != 0
226
233
240
247
254
255 - def from_text(cls, rdclass, rdtype, tok, origin = None, relativize = True):
256 """Build an rdata object from text format.
257
258 @param rdclass: The rdata class
259 @type rdclass: int
260 @param rdtype: The rdata type
261 @type rdtype: int
262 @param tok: The tokenizer
263 @type tok: dns.tokenizer.Tokenizer
264 @param origin: The origin to use for relative names
265 @type origin: dns.name.Name
266 @param relativize: should names be relativized?
267 @type relativize: bool
268 @rtype: dns.rdata.Rdata instance
269 """
270
271 raise NotImplementedError
272
273 from_text = classmethod(from_text)
274
275 - def from_wire(cls, rdclass, rdtype, wire, current, rdlen, origin = None):
276 """Build an rdata object from wire format
277
278 @param rdclass: The rdata class
279 @type rdclass: int
280 @param rdtype: The rdata type
281 @type rdtype: int
282 @param wire: The wire-format message
283 @type wire: string
284 @param current: The offet in wire of the beginning of the rdata.
285 @type current: int
286 @param rdlen: The length of the wire-format rdata
287 @type rdlen: int
288 @param origin: The origin to use for relative names
289 @type origin: dns.name.Name
290 @rtype: dns.rdata.Rdata instance
291 """
292
293 raise NotImplementedError
294
295 from_wire = classmethod(from_wire)
296
298 """Convert any domain names in the rdata to the specified
299 relativization.
300 """
301
302 pass
303
304
306 """Generate Rdata Class
307
308 This class is used for rdata types for which we have no better
309 implementation. It implements the DNS "unknown RRs" scheme.
310 """
311
312 __slots__ = ['data']
313
314 - def __init__(self, rdclass, rdtype, data):
317
318 - def to_text(self, origin=None, relativize=True, **kw):
319 return r'\# %d ' % len(self.data) + _hexify(self.data)
320
321 - def from_text(cls, rdclass, rdtype, tok, origin = None, relativize = True):
322 token = tok.get()
323 if not token.is_identifier() or token.value != '\#':
324 raise dns.exception.SyntaxError(r'generic rdata does not start with \#')
325 length = tok.get_int()
326 chunks = []
327 while 1:
328 token = tok.get()
329 if token.is_eol_or_eof():
330 break
331 chunks.append(token.value)
332 hex = ''.join(chunks)
333 data = hex.decode('hex_codec')
334 if len(data) != length:
335 raise dns.exception.SyntaxError('generic rdata hex data has wrong length')
336 return cls(rdclass, rdtype, data)
337
338 from_text = classmethod(from_text)
339
340 - def to_wire(self, file, compress = None, origin = None):
341 file.write(self.data)
342
343 - def from_wire(cls, rdclass, rdtype, wire, current, rdlen, origin = None):
345
346 from_wire = classmethod(from_wire)
347
348 - def _cmp(self, other):
350
351 _rdata_modules = {}
352 _module_prefix = 'dns.rdtypes'
353
355
356 def import_module(name):
357 mod = __import__(name)
358 components = name.split('.')
359 for comp in components[1:]:
360 mod = getattr(mod, comp)
361 return mod
362
363 mod = _rdata_modules.get((rdclass, rdtype))
364 rdclass_text = dns.rdataclass.to_text(rdclass)
365 rdtype_text = dns.rdatatype.to_text(rdtype)
366 rdtype_text = rdtype_text.replace('-', '_')
367 if not mod:
368 mod = _rdata_modules.get((dns.rdatatype.ANY, rdtype))
369 if not mod:
370 try:
371 mod = import_module('.'.join([_module_prefix,
372 rdclass_text, rdtype_text]))
373 _rdata_modules[(rdclass, rdtype)] = mod
374 except ImportError:
375 try:
376 mod = import_module('.'.join([_module_prefix,
377 'ANY', rdtype_text]))
378 _rdata_modules[(dns.rdataclass.ANY, rdtype)] = mod
379 except ImportError:
380 mod = None
381 if mod:
382 cls = getattr(mod, rdtype_text)
383 else:
384 cls = GenericRdata
385 return cls
386
387 -def from_text(rdclass, rdtype, tok, origin = None, relativize = True):
388 """Build an rdata object from text format.
389
390 This function attempts to dynamically load a class which
391 implements the specified rdata class and type. If there is no
392 class-and-type-specific implementation, the GenericRdata class
393 is used.
394
395 Once a class is chosen, its from_text() class method is called
396 with the parameters to this function.
397
398 @param rdclass: The rdata class
399 @type rdclass: int
400 @param rdtype: The rdata type
401 @type rdtype: int
402 @param tok: The tokenizer
403 @type tok: dns.tokenizer.Tokenizer
404 @param origin: The origin to use for relative names
405 @type origin: dns.name.Name
406 @param relativize: Should names be relativized?
407 @type relativize: bool
408 @rtype: dns.rdata.Rdata instance"""
409
410 if isinstance(tok, str):
411 tok = dns.tokenizer.Tokenizer(tok)
412 cls = get_rdata_class(rdclass, rdtype)
413 if cls != GenericRdata:
414
415 token = tok.get()
416 tok.unget(token)
417 if token.is_identifier() and \
418 token.value == r'\#':
419
420
421
422
423
424 rdata = GenericRdata.from_text(rdclass, rdtype, tok, origin,
425 relativize)
426 return from_wire(rdclass, rdtype, rdata.data, 0, len(rdata.data),
427 origin)
428 return cls.from_text(rdclass, rdtype, tok, origin, relativize)
429
430 -def from_wire(rdclass, rdtype, wire, current, rdlen, origin = None):
431 """Build an rdata object from wire format
432
433 This function attempts to dynamically load a class which
434 implements the specified rdata class and type. If there is no
435 class-and-type-specific implementation, the GenericRdata class
436 is used.
437
438 Once a class is chosen, its from_wire() class method is called
439 with the parameters to this function.
440
441 @param rdclass: The rdata class
442 @type rdclass: int
443 @param rdtype: The rdata type
444 @type rdtype: int
445 @param wire: The wire-format message
446 @type wire: string
447 @param current: The offet in wire of the beginning of the rdata.
448 @type current: int
449 @param rdlen: The length of the wire-format rdata
450 @type rdlen: int
451 @param origin: The origin to use for relative names
452 @type origin: dns.name.Name
453 @rtype: dns.rdata.Rdata instance"""
454
455 cls = get_rdata_class(rdclass, rdtype)
456 return cls.from_wire(rdclass, rdtype, wire, current, rdlen, origin)
457