1# Copyright (C) 2001-2017 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"""DNS rdatasets (an rdataset is a set of rdatas of a given type and class)""" 17 18import random 19from io import StringIO 20import struct 21 22import dns.exception 23import dns.rdatatype 24import dns.rdataclass 25import dns.rdata 26import dns.set 27from ._compat import string_types 28 29# define SimpleSet here for backwards compatibility 30SimpleSet = dns.set.Set 31 32 33class DifferingCovers(dns.exception.DNSException): 34 """An attempt was made to add a DNS SIG/RRSIG whose covered type 35 is not the same as that of the other rdatas in the rdataset.""" 36 37 38class IncompatibleTypes(dns.exception.DNSException): 39 """An attempt was made to add DNS RR data of an incompatible type.""" 40 41 42class Rdataset(dns.set.Set): 43 44 """A DNS rdataset.""" 45 46 __slots__ = ['rdclass', 'rdtype', 'covers', 'ttl'] 47 48 def __init__(self, rdclass, rdtype, covers=dns.rdatatype.NONE, ttl=0): 49 """Create a new rdataset of the specified class and type. 50 51 *rdclass*, an ``int``, the rdataclass. 52 53 *rdtype*, an ``int``, the rdatatype. 54 55 *covers*, an ``int``, the covered rdatatype. 56 57 *ttl*, an ``int``, the TTL. 58 """ 59 60 super(Rdataset, self).__init__() 61 self.rdclass = rdclass 62 self.rdtype = rdtype 63 self.covers = covers 64 self.ttl = ttl 65 66 def _clone(self): 67 obj = super(Rdataset, self)._clone() 68 obj.rdclass = self.rdclass 69 obj.rdtype = self.rdtype 70 obj.covers = self.covers 71 obj.ttl = self.ttl 72 return obj 73 74 def update_ttl(self, ttl): 75 """Perform TTL minimization. 76 77 Set the TTL of the rdataset to be the lesser of the set's current 78 TTL or the specified TTL. If the set contains no rdatas, set the TTL 79 to the specified TTL. 80 81 *ttl*, an ``int``. 82 """ 83 84 if len(self) == 0: 85 self.ttl = ttl 86 elif ttl < self.ttl: 87 self.ttl = ttl 88 89 def add(self, rd, ttl=None): 90 """Add the specified rdata to the rdataset. 91 92 If the optional *ttl* parameter is supplied, then 93 ``self.update_ttl(ttl)`` will be called prior to adding the rdata. 94 95 *rd*, a ``dns.rdata.Rdata``, the rdata 96 97 *ttl*, an ``int``, the TTL. 98 99 Raises ``dns.rdataset.IncompatibleTypes`` if the type and class 100 do not match the type and class of the rdataset. 101 102 Raises ``dns.rdataset.DifferingCovers`` if the type is a signature 103 type and the covered type does not match that of the rdataset. 104 """ 105 106 # 107 # If we're adding a signature, do some special handling to 108 # check that the signature covers the same type as the 109 # other rdatas in this rdataset. If this is the first rdata 110 # in the set, initialize the covers field. 111 # 112 if self.rdclass != rd.rdclass or self.rdtype != rd.rdtype: 113 raise IncompatibleTypes 114 if ttl is not None: 115 self.update_ttl(ttl) 116 if self.rdtype == dns.rdatatype.RRSIG or \ 117 self.rdtype == dns.rdatatype.SIG: 118 covers = rd.covers() 119 if len(self) == 0 and self.covers == dns.rdatatype.NONE: 120 self.covers = covers 121 elif self.covers != covers: 122 raise DifferingCovers 123 if dns.rdatatype.is_singleton(rd.rdtype) and len(self) > 0: 124 self.clear() 125 super(Rdataset, self).add(rd) 126 127 def union_update(self, other): 128 self.update_ttl(other.ttl) 129 super(Rdataset, self).union_update(other) 130 131 def intersection_update(self, other): 132 self.update_ttl(other.ttl) 133 super(Rdataset, self).intersection_update(other) 134 135 def update(self, other): 136 """Add all rdatas in other to self. 137 138 *other*, a ``dns.rdataset.Rdataset``, the rdataset from which 139 to update. 140 """ 141 142 self.update_ttl(other.ttl) 143 super(Rdataset, self).update(other) 144 145 def __repr__(self): 146 if self.covers == 0: 147 ctext = '' 148 else: 149 ctext = '(' + dns.rdatatype.to_text(self.covers) + ')' 150 return '<DNS ' + dns.rdataclass.to_text(self.rdclass) + ' ' + \ 151 dns.rdatatype.to_text(self.rdtype) + ctext + ' rdataset>' 152 153 def __str__(self): 154 return self.to_text() 155 156 def __eq__(self, other): 157 if not isinstance(other, Rdataset): 158 return False 159 if self.rdclass != other.rdclass or \ 160 self.rdtype != other.rdtype or \ 161 self.covers != other.covers: 162 return False 163 return super(Rdataset, self).__eq__(other) 164 165 def __ne__(self, other): 166 return not self.__eq__(other) 167 168 def to_text(self, name=None, origin=None, relativize=True, 169 override_rdclass=None, **kw): 170 """Convert the rdataset into DNS master file format. 171 172 See ``dns.name.Name.choose_relativity`` for more information 173 on how *origin* and *relativize* determine the way names 174 are emitted. 175 176 Any additional keyword arguments are passed on to the rdata 177 ``to_text()`` method. 178 179 *name*, a ``dns.name.Name``. If name is not ``None``, emit RRs with 180 *name* as the owner name. 181 182 *origin*, a ``dns.name.Name`` or ``None``, the origin for relative 183 names. 184 185 *relativize*, a ``bool``. If ``True``, names will be relativized 186 to *origin*. 187 """ 188 189 if name is not None: 190 name = name.choose_relativity(origin, relativize) 191 ntext = str(name) 192 pad = ' ' 193 else: 194 ntext = '' 195 pad = '' 196 s = StringIO() 197 if override_rdclass is not None: 198 rdclass = override_rdclass 199 else: 200 rdclass = self.rdclass 201 if len(self) == 0: 202 # 203 # Empty rdatasets are used for the question section, and in 204 # some dynamic updates, so we don't need to print out the TTL 205 # (which is meaningless anyway). 206 # 207 s.write(u'%s%s%s %s\n' % (ntext, pad, 208 dns.rdataclass.to_text(rdclass), 209 dns.rdatatype.to_text(self.rdtype))) 210 else: 211 for rd in self: 212 s.write(u'%s%s%d %s %s %s\n' % 213 (ntext, pad, self.ttl, dns.rdataclass.to_text(rdclass), 214 dns.rdatatype.to_text(self.rdtype), 215 rd.to_text(origin=origin, relativize=relativize, 216 **kw))) 217 # 218 # We strip off the final \n for the caller's convenience in printing 219 # 220 return s.getvalue()[:-1] 221 222 def to_wire(self, name, file, compress=None, origin=None, 223 override_rdclass=None, want_shuffle=True): 224 """Convert the rdataset to wire format. 225 226 *name*, a ``dns.name.Name`` is the owner name to use. 227 228 *file* is the file where the name is emitted (typically a 229 BytesIO file). 230 231 *compress*, a ``dict``, is the compression table to use. If 232 ``None`` (the default), names will not be compressed. 233 234 *origin* is a ``dns.name.Name`` or ``None``. If the name is 235 relative and origin is not ``None``, then *origin* will be appended 236 to it. 237 238 *override_rdclass*, an ``int``, is used as the class instead of the 239 class of the rdataset. This is useful when rendering rdatasets 240 associated with dynamic updates. 241 242 *want_shuffle*, a ``bool``. If ``True``, then the order of the 243 Rdatas within the Rdataset will be shuffled before rendering. 244 245 Returns an ``int``, the number of records emitted. 246 """ 247 248 if override_rdclass is not None: 249 rdclass = override_rdclass 250 want_shuffle = False 251 else: 252 rdclass = self.rdclass 253 file.seek(0, 2) 254 if len(self) == 0: 255 name.to_wire(file, compress, origin) 256 stuff = struct.pack("!HHIH", self.rdtype, rdclass, 0, 0) 257 file.write(stuff) 258 return 1 259 else: 260 if want_shuffle: 261 l = list(self) 262 random.shuffle(l) 263 else: 264 l = self 265 for rd in l: 266 name.to_wire(file, compress, origin) 267 stuff = struct.pack("!HHIH", self.rdtype, rdclass, 268 self.ttl, 0) 269 file.write(stuff) 270 start = file.tell() 271 rd.to_wire(file, compress, origin) 272 end = file.tell() 273 assert end - start < 65536 274 file.seek(start - 2) 275 stuff = struct.pack("!H", end - start) 276 file.write(stuff) 277 file.seek(0, 2) 278 return len(self) 279 280 def match(self, rdclass, rdtype, covers): 281 """Returns ``True`` if this rdataset matches the specified class, 282 type, and covers. 283 """ 284 if self.rdclass == rdclass and \ 285 self.rdtype == rdtype and \ 286 self.covers == covers: 287 return True 288 return False 289 290 291def from_text_list(rdclass, rdtype, ttl, text_rdatas): 292 """Create an rdataset with the specified class, type, and TTL, and with 293 the specified list of rdatas in text format. 294 295 Returns a ``dns.rdataset.Rdataset`` object. 296 """ 297 298 if isinstance(rdclass, string_types): 299 rdclass = dns.rdataclass.from_text(rdclass) 300 if isinstance(rdtype, string_types): 301 rdtype = dns.rdatatype.from_text(rdtype) 302 r = Rdataset(rdclass, rdtype) 303 r.update_ttl(ttl) 304 for t in text_rdatas: 305 rd = dns.rdata.from_text(r.rdclass, r.rdtype, t) 306 r.add(rd) 307 return r 308 309 310def from_text(rdclass, rdtype, ttl, *text_rdatas): 311 """Create an rdataset with the specified class, type, and TTL, and with 312 the specified rdatas in text format. 313 314 Returns a ``dns.rdataset.Rdataset`` object. 315 """ 316 317 return from_text_list(rdclass, rdtype, ttl, text_rdatas) 318 319 320def from_rdata_list(ttl, rdatas): 321 """Create an rdataset with the specified TTL, and with 322 the specified list of rdata objects. 323 324 Returns a ``dns.rdataset.Rdataset`` object. 325 """ 326 327 if len(rdatas) == 0: 328 raise ValueError("rdata list must not be empty") 329 r = None 330 for rd in rdatas: 331 if r is None: 332 r = Rdataset(rd.rdclass, rd.rdtype) 333 r.update_ttl(ttl) 334 r.add(rd) 335 return r 336 337 338def from_rdata(ttl, *rdatas): 339 """Create an rdataset with the specified TTL, and with 340 the specified rdata objects. 341 342 Returns a ``dns.rdataset.Rdataset`` object. 343 """ 344 345 return from_rdata_list(ttl, rdatas) 346