Source code for dns.rdataset

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"""DNS rdatasets (an rdataset is a set of rdatas of a given type and class)"""

from typing import Any, cast, Collection, Dict, List, Optional, Union

import io
import random
import struct

import dns.exception
import dns.immutable
import dns.name
import dns.rdatatype
import dns.rdataclass
import dns.rdata
import dns.set
import dns.ttl

# define SimpleSet here for backwards compatibility
SimpleSet = dns.set.Set


[docs]class DifferingCovers(dns.exception.DNSException): """An attempt was made to add a DNS SIG/RRSIG whose covered type is not the same as that of the other rdatas in the rdataset."""
[docs]class IncompatibleTypes(dns.exception.DNSException): """An attempt was made to add DNS RR data of an incompatible type."""
[docs]class Rdataset(dns.set.Set): """A DNS rdataset.""" __slots__ = ["rdclass", "rdtype", "covers", "ttl"] def __init__( self, rdclass: dns.rdataclass.RdataClass, rdtype: dns.rdatatype.RdataType, covers: dns.rdatatype.RdataType = dns.rdatatype.NONE, ttl: int = 0, ): """Create a new rdataset of the specified class and type. *rdclass*, a ``dns.rdataclass.RdataClass``, the rdataclass. *rdtype*, an ``dns.rdatatype.RdataType``, the rdatatype. *covers*, an ``dns.rdatatype.RdataType``, the covered rdatatype. *ttl*, an ``int``, the TTL. """ super().__init__() self.rdclass = rdclass self.rdtype: dns.rdatatype.RdataType = rdtype self.covers: dns.rdatatype.RdataType = covers self.ttl = ttl def _clone(self): obj = super()._clone() obj.rdclass = self.rdclass obj.rdtype = self.rdtype obj.covers = self.covers obj.ttl = self.ttl return obj
[docs] def update_ttl(self, ttl: int) -> None: """Perform TTL minimization. Set the TTL of the rdataset to be the lesser of the set's current TTL or the specified TTL. If the set contains no rdatas, set the TTL to the specified TTL. *ttl*, an ``int`` or ``str``. """ ttl = dns.ttl.make(ttl) if len(self) == 0: self.ttl = ttl elif ttl < self.ttl: self.ttl = ttl
[docs] def add( # pylint: disable=arguments-differ,arguments-renamed self, rd: dns.rdata.Rdata, ttl: Optional[int] = None ) -> None: """Add the specified rdata to the rdataset. If the optional *ttl* parameter is supplied, then ``self.update_ttl(ttl)`` will be called prior to adding the rdata. *rd*, a ``dns.rdata.Rdata``, the rdata *ttl*, an ``int``, the TTL. Raises ``dns.rdataset.IncompatibleTypes`` if the type and class do not match the type and class of the rdataset. Raises ``dns.rdataset.DifferingCovers`` if the type is a signature type and the covered type does not match that of the rdataset. """ # # If we're adding a signature, do some special handling to # check that the signature covers the same type as the # other rdatas in this rdataset. If this is the first rdata # in the set, initialize the covers field. # if self.rdclass != rd.rdclass or self.rdtype != rd.rdtype: raise IncompatibleTypes if ttl is not None: self.update_ttl(ttl) if self.rdtype == dns.rdatatype.RRSIG or self.rdtype == dns.rdatatype.SIG: covers = rd.covers() if len(self) == 0 and self.covers == dns.rdatatype.NONE: self.covers = covers elif self.covers != covers: raise DifferingCovers if dns.rdatatype.is_singleton(rd.rdtype) and len(self) > 0: self.clear() super().add(rd)
[docs] def union_update(self, other): self.update_ttl(other.ttl) super().union_update(other)
[docs] def intersection_update(self, other): self.update_ttl(other.ttl) super().intersection_update(other)
[docs] def update(self, other): """Add all rdatas in other to self. *other*, a ``dns.rdataset.Rdataset``, the rdataset from which to update. """ self.update_ttl(other.ttl) super().update(other)
def _rdata_repr(self): def maybe_truncate(s): if len(s) > 100: return s[:100] + "..." return s return "[%s]" % ", ".join("<%s>" % maybe_truncate(str(rr)) for rr in self) def __repr__(self): if self.covers == 0: ctext = "" else: ctext = "(" + dns.rdatatype.to_text(self.covers) + ")" return ( "<DNS " + dns.rdataclass.to_text(self.rdclass) + " " + dns.rdatatype.to_text(self.rdtype) + ctext + " rdataset: " + self._rdata_repr() + ">" ) def __str__(self): return self.to_text() def __eq__(self, other): if not isinstance(other, Rdataset): return False if ( self.rdclass != other.rdclass or self.rdtype != other.rdtype or self.covers != other.covers ): return False return super().__eq__(other) def __ne__(self, other): return not self.__eq__(other)
[docs] def to_text( self, name: Optional[dns.name.Name] = None, origin: Optional[dns.name.Name] = None, relativize: bool = True, override_rdclass: Optional[dns.rdataclass.RdataClass] = None, want_comments: bool = False, **kw: Dict[str, Any], ) -> str: """Convert the rdataset into DNS zone file format. See ``dns.name.Name.choose_relativity`` for more information on how *origin* and *relativize* determine the way names are emitted. Any additional keyword arguments are passed on to the rdata ``to_text()`` method. *name*, a ``dns.name.Name``. If name is not ``None``, emit RRs with *name* as the owner name. *origin*, a ``dns.name.Name`` or ``None``, the origin for relative names. *relativize*, a ``bool``. If ``True``, names will be relativized to *origin*. *override_rdclass*, a ``dns.rdataclass.RdataClass`` or ``None``. If not ``None``, use this class instead of the Rdataset's class. *want_comments*, a ``bool``. If ``True``, emit comments for rdata which have them. The default is ``False``. """ if name is not None: name = name.choose_relativity(origin, relativize) ntext = str(name) pad = " " else: ntext = "" pad = "" s = io.StringIO() if override_rdclass is not None: rdclass = override_rdclass else: rdclass = self.rdclass if len(self) == 0: # # Empty rdatasets are used for the question section, and in # some dynamic updates, so we don't need to print out the TTL # (which is meaningless anyway). # s.write( "{}{}{} {}\n".format( ntext, pad, dns.rdataclass.to_text(rdclass), dns.rdatatype.to_text(self.rdtype), ) ) else: for rd in self: extra = "" if want_comments: if rd.rdcomment: extra = f" ;{rd.rdcomment}" s.write( "%s%s%d %s %s %s%s\n" % ( ntext, pad, self.ttl, dns.rdataclass.to_text(rdclass), dns.rdatatype.to_text(self.rdtype), rd.to_text(origin=origin, relativize=relativize, **kw), extra, ) ) # # We strip off the final \n for the caller's convenience in printing # return s.getvalue()[:-1]
[docs] def to_wire( self, name: dns.name.Name, file: Any, compress: Optional[dns.name.CompressType] = None, origin: Optional[dns.name.Name] = None, override_rdclass: Optional[dns.rdataclass.RdataClass] = None, want_shuffle: bool = True, ) -> int: """Convert the rdataset to wire format. *name*, a ``dns.name.Name`` is the owner name to use. *file* is the file where the name is emitted (typically a BytesIO file). *compress*, a ``dict``, is the compression table to use. If ``None`` (the default), names will not be compressed. *origin* is a ``dns.name.Name`` or ``None``. If the name is relative and origin is not ``None``, then *origin* will be appended to it. *override_rdclass*, an ``int``, is used as the class instead of the class of the rdataset. This is useful when rendering rdatasets associated with dynamic updates. *want_shuffle*, a ``bool``. If ``True``, then the order of the Rdatas within the Rdataset will be shuffled before rendering. Returns an ``int``, the number of records emitted. """ if override_rdclass is not None: rdclass = override_rdclass want_shuffle = False else: rdclass = self.rdclass file.seek(0, io.SEEK_END) if len(self) == 0: name.to_wire(file, compress, origin) stuff = struct.pack("!HHIH", self.rdtype, rdclass, 0, 0) file.write(stuff) return 1 else: l: Union[Rdataset, List[dns.rdata.Rdata]] if want_shuffle: l = list(self) random.shuffle(l) else: l = self for rd in l: name.to_wire(file, compress, origin) stuff = struct.pack("!HHIH", self.rdtype, rdclass, self.ttl, 0) file.write(stuff) start = file.tell() rd.to_wire(file, compress, origin) end = file.tell() assert end - start < 65536 file.seek(start - 2) stuff = struct.pack("!H", end - start) file.write(stuff) file.seek(0, io.SEEK_END) return len(self)
[docs] def match( self, rdclass: dns.rdataclass.RdataClass, rdtype: dns.rdatatype.RdataType, covers: dns.rdatatype.RdataType, ) -> bool: """Returns ``True`` if this rdataset matches the specified class, type, and covers. """ if self.rdclass == rdclass and self.rdtype == rdtype and self.covers == covers: return True return False
[docs] def processing_order(self) -> List[dns.rdata.Rdata]: """Return rdatas in a valid processing order according to the type's specification. For example, MX records are in preference order from lowest to highest preferences, with items of the same preference shuffled. For types that do not define a processing order, the rdatas are simply shuffled. """ if len(self) == 0: return [] else: return self[0]._processing_order(iter(self))
@dns.immutable.immutable class ImmutableRdataset(Rdataset): # lgtm[py/missing-equals] """An immutable DNS rdataset.""" _clone_class = Rdataset def __init__(self, rdataset: Rdataset): """Create an immutable rdataset from the specified rdataset.""" super().__init__( rdataset.rdclass, rdataset.rdtype, rdataset.covers, rdataset.ttl ) self.items = dns.immutable.Dict(rdataset.items) def update_ttl(self, ttl): raise TypeError("immutable") def add(self, rd, ttl=None): raise TypeError("immutable") def union_update(self, other): raise TypeError("immutable") def intersection_update(self, other): raise TypeError("immutable") def update(self, other): raise TypeError("immutable") def __delitem__(self, i): raise TypeError("immutable") # lgtm complains about these not raising ArithmeticError, but there is # precedent for overrides of these methods in other classes to raise # TypeError, and it seems like the better exception. def __ior__(self, other): # lgtm[py/unexpected-raise-in-special-method] raise TypeError("immutable") def __iand__(self, other): # lgtm[py/unexpected-raise-in-special-method] raise TypeError("immutable") def __iadd__(self, other): # lgtm[py/unexpected-raise-in-special-method] raise TypeError("immutable") def __isub__(self, other): # lgtm[py/unexpected-raise-in-special-method] raise TypeError("immutable") def clear(self): raise TypeError("immutable") def __copy__(self): return ImmutableRdataset(super().copy()) def copy(self): return ImmutableRdataset(super().copy()) def union(self, other): return ImmutableRdataset(super().union(other)) def intersection(self, other): return ImmutableRdataset(super().intersection(other)) def difference(self, other): return ImmutableRdataset(super().difference(other)) def symmetric_difference(self, other): return ImmutableRdataset(super().symmetric_difference(other))
[docs]def from_text_list( rdclass: Union[dns.rdataclass.RdataClass, str], rdtype: Union[dns.rdatatype.RdataType, str], ttl: int, text_rdatas: Collection[str], idna_codec: Optional[dns.name.IDNACodec] = None, origin: Optional[dns.name.Name] = None, relativize: bool = True, relativize_to: Optional[dns.name.Name] = None, ) -> Rdataset: """Create an rdataset with the specified class, type, and TTL, and with the specified list of rdatas in text format. *idna_codec*, a ``dns.name.IDNACodec``, specifies the IDNA encoder/decoder to use; if ``None``, the default IDNA 2003 encoder/decoder is used. *origin*, a ``dns.name.Name`` (or ``None``), the origin to use for relative names. *relativize*, a ``bool``. If true, name will be relativized. *relativize_to*, a ``dns.name.Name`` (or ``None``), the origin to use when relativizing names. If not set, the *origin* value will be used. Returns a ``dns.rdataset.Rdataset`` object. """ the_rdclass = dns.rdataclass.RdataClass.make(rdclass) the_rdtype = dns.rdatatype.RdataType.make(rdtype) r = Rdataset(the_rdclass, the_rdtype) r.update_ttl(ttl) for t in text_rdatas: rd = dns.rdata.from_text( r.rdclass, r.rdtype, t, origin, relativize, relativize_to, idna_codec ) r.add(rd) return r
[docs]def from_text( rdclass: Union[dns.rdataclass.RdataClass, str], rdtype: Union[dns.rdatatype.RdataType, str], ttl: int, *text_rdatas: Any, ) -> Rdataset: """Create an rdataset with the specified class, type, and TTL, and with the specified rdatas in text format. Returns a ``dns.rdataset.Rdataset`` object. """ return from_text_list(rdclass, rdtype, ttl, cast(Collection[str], text_rdatas))
[docs]def from_rdata_list(ttl: int, rdatas: Collection[dns.rdata.Rdata]) -> Rdataset: """Create an rdataset with the specified TTL, and with the specified list of rdata objects. Returns a ``dns.rdataset.Rdataset`` object. """ if len(rdatas) == 0: raise ValueError("rdata list must not be empty") r = None for rd in rdatas: if r is None: r = Rdataset(rd.rdclass, rd.rdtype) r.update_ttl(ttl) r.add(rd) assert r is not None return r
[docs]def from_rdata(ttl: int, *rdatas: Any) -> Rdataset: """Create an rdataset with the specified TTL, and with the specified rdata objects. Returns a ``dns.rdataset.Rdataset`` object. """ return from_rdata_list(ttl, cast(Collection[dns.rdata.Rdata], rdatas))