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Diffstat (limited to '.venv/lib/python3.12/site-packages/dns/rdata.py')
| -rw-r--r-- | .venv/lib/python3.12/site-packages/dns/rdata.py | 911 |
1 files changed, 911 insertions, 0 deletions
diff --git a/.venv/lib/python3.12/site-packages/dns/rdata.py b/.venv/lib/python3.12/site-packages/dns/rdata.py new file mode 100644 index 00000000..8099c26a --- /dev/null +++ b/.venv/lib/python3.12/site-packages/dns/rdata.py @@ -0,0 +1,911 @@ +# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license + +# Copyright (C) 2001-2017 Nominum, Inc. +# +# Permission to use, copy, modify, and distribute this software and its +# documentation for any purpose with or without fee is hereby granted, +# provided that the above copyright notice and this permission notice +# appear in all copies. +# +# THE SOFTWARE IS PROVIDED "AS IS" AND NOMINUM DISCLAIMS ALL WARRANTIES +# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF +# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NOMINUM BE LIABLE FOR +# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES +# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN +# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT +# OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + +"""DNS rdata.""" + +import base64 +import binascii +import inspect +import io +import itertools +import random +from importlib import import_module +from typing import Any, Dict, Optional, Tuple, Union + +import dns.exception +import dns.immutable +import dns.ipv4 +import dns.ipv6 +import dns.name +import dns.rdataclass +import dns.rdatatype +import dns.tokenizer +import dns.ttl +import dns.wire + +_chunksize = 32 + +# We currently allow comparisons for rdata with relative names for backwards +# compatibility, but in the future we will not, as these kinds of comparisons +# can lead to subtle bugs if code is not carefully written. +# +# This switch allows the future behavior to be turned on so code can be +# tested with it. +_allow_relative_comparisons = True + + +class NoRelativeRdataOrdering(dns.exception.DNSException): + """An attempt was made to do an ordered comparison of one or more + rdata with relative names. The only reliable way of sorting rdata + is to use non-relativized rdata. + + """ + + +def _wordbreak(data, chunksize=_chunksize, separator=b" "): + """Break a binary string into chunks of chunksize characters separated by + a space. + """ + + if not chunksize: + return data.decode() + return separator.join( + [data[i : i + chunksize] for i in range(0, len(data), chunksize)] + ).decode() + + +# pylint: disable=unused-argument + + +def _hexify(data, chunksize=_chunksize, separator=b" ", **kw): + """Convert a binary string into its hex encoding, broken up into chunks + of chunksize characters separated by a separator. + """ + + return _wordbreak(binascii.hexlify(data), chunksize, separator) + + +def _base64ify(data, chunksize=_chunksize, separator=b" ", **kw): + """Convert a binary string into its base64 encoding, broken up into chunks + of chunksize characters separated by a separator. + """ + + return _wordbreak(base64.b64encode(data), chunksize, separator) + + +# pylint: enable=unused-argument + +__escaped = b'"\\' + + +def _escapify(qstring): + """Escape the characters in a quoted string which need it.""" + + if isinstance(qstring, str): + qstring = qstring.encode() + if not isinstance(qstring, bytearray): + qstring = bytearray(qstring) + + text = "" + for c in qstring: + if c in __escaped: + text += "\\" + chr(c) + elif c >= 0x20 and c < 0x7F: + text += chr(c) + else: + text += "\\%03d" % c + return text + + +def _truncate_bitmap(what): + """Determine the index of greatest byte that isn't all zeros, and + return the bitmap that contains all the bytes less than that index. + """ + + for i in range(len(what) - 1, -1, -1): + if what[i] != 0: + return what[0 : i + 1] + return what[0:1] + + +# So we don't have to edit all the rdata classes... +_constify = dns.immutable.constify + + +@dns.immutable.immutable +class Rdata: + """Base class for all DNS rdata types.""" + + __slots__ = ["rdclass", "rdtype", "rdcomment"] + + def __init__(self, rdclass, rdtype): + """Initialize an rdata. + + *rdclass*, an ``int`` is the rdataclass of the Rdata. + + *rdtype*, an ``int`` is the rdatatype of the Rdata. + """ + + self.rdclass = self._as_rdataclass(rdclass) + self.rdtype = self._as_rdatatype(rdtype) + self.rdcomment = None + + def _get_all_slots(self): + return itertools.chain.from_iterable( + getattr(cls, "__slots__", []) for cls in self.__class__.__mro__ + ) + + def __getstate__(self): + # We used to try to do a tuple of all slots here, but it + # doesn't work as self._all_slots isn't available at + # __setstate__() time. Before that we tried to store a tuple + # of __slots__, but that didn't work as it didn't store the + # slots defined by ancestors. This older way didn't fail + # outright, but ended up with partially broken objects, e.g. + # if you unpickled an A RR it wouldn't have rdclass and rdtype + # attributes, and would compare badly. + state = {} + for slot in self._get_all_slots(): + state[slot] = getattr(self, slot) + return state + + def __setstate__(self, state): + for slot, val in state.items(): + object.__setattr__(self, slot, val) + if not hasattr(self, "rdcomment"): + # Pickled rdata from 2.0.x might not have a rdcomment, so add + # it if needed. + object.__setattr__(self, "rdcomment", None) + + def covers(self) -> dns.rdatatype.RdataType: + """Return the type a Rdata covers. + + DNS SIG/RRSIG rdatas apply to a specific type; this type is + returned by the covers() function. If the rdata type is not + SIG or RRSIG, dns.rdatatype.NONE is returned. This is useful when + creating rdatasets, allowing the rdataset to contain only RRSIGs + of a particular type, e.g. RRSIG(NS). + + Returns a ``dns.rdatatype.RdataType``. + """ + + return dns.rdatatype.NONE + + def extended_rdatatype(self) -> int: + """Return a 32-bit type value, the least significant 16 bits of + which are the ordinary DNS type, and the upper 16 bits of which are + the "covered" type, if any. + + Returns an ``int``. + """ + + return self.covers() << 16 | self.rdtype + + def to_text( + self, + origin: Optional[dns.name.Name] = None, + relativize: bool = True, + **kw: Dict[str, Any], + ) -> str: + """Convert an rdata to text format. + + Returns a ``str``. + """ + + raise NotImplementedError # pragma: no cover + + def _to_wire( + self, + file: Optional[Any], + compress: Optional[dns.name.CompressType] = None, + origin: Optional[dns.name.Name] = None, + canonicalize: bool = False, + ) -> None: + raise NotImplementedError # pragma: no cover + + def to_wire( + self, + file: Optional[Any] = None, + compress: Optional[dns.name.CompressType] = None, + origin: Optional[dns.name.Name] = None, + canonicalize: bool = False, + ) -> Optional[bytes]: + """Convert an rdata to wire format. + + Returns a ``bytes`` if no output file was specified, or ``None`` otherwise. + """ + + if file: + # We call _to_wire() and then return None explicitly instead of + # of just returning the None from _to_wire() as mypy's func-returns-value + # unhelpfully errors out with "error: "_to_wire" of "Rdata" does not return + # a value (it only ever returns None)" + self._to_wire(file, compress, origin, canonicalize) + return None + else: + f = io.BytesIO() + self._to_wire(f, compress, origin, canonicalize) + return f.getvalue() + + def to_generic( + self, origin: Optional[dns.name.Name] = None + ) -> "dns.rdata.GenericRdata": + """Creates a dns.rdata.GenericRdata equivalent of this rdata. + + Returns a ``dns.rdata.GenericRdata``. + """ + return dns.rdata.GenericRdata( + self.rdclass, self.rdtype, self.to_wire(origin=origin) + ) + + def to_digestable(self, origin: Optional[dns.name.Name] = None) -> bytes: + """Convert rdata to a format suitable for digesting in hashes. This + is also the DNSSEC canonical form. + + Returns a ``bytes``. + """ + wire = self.to_wire(origin=origin, canonicalize=True) + assert wire is not None # for mypy + return wire + + def __repr__(self): + covers = self.covers() + if covers == dns.rdatatype.NONE: + ctext = "" + else: + ctext = "(" + dns.rdatatype.to_text(covers) + ")" + return ( + "<DNS " + + dns.rdataclass.to_text(self.rdclass) + + " " + + dns.rdatatype.to_text(self.rdtype) + + ctext + + " rdata: " + + str(self) + + ">" + ) + + def __str__(self): + return self.to_text() + + def _cmp(self, other): + """Compare an rdata with another rdata of the same rdtype and + rdclass. + + For rdata with only absolute names: + Return < 0 if self < other in the DNSSEC ordering, 0 if self + == other, and > 0 if self > other. + For rdata with at least one relative names: + The rdata sorts before any rdata with only absolute names. + When compared with another relative rdata, all names are + made absolute as if they were relative to the root, as the + proper origin is not available. While this creates a stable + ordering, it is NOT guaranteed to be the DNSSEC ordering. + In the future, all ordering comparisons for rdata with + relative names will be disallowed. + """ + try: + our = self.to_digestable() + our_relative = False + except dns.name.NeedAbsoluteNameOrOrigin: + if _allow_relative_comparisons: + our = self.to_digestable(dns.name.root) + our_relative = True + try: + their = other.to_digestable() + their_relative = False + except dns.name.NeedAbsoluteNameOrOrigin: + if _allow_relative_comparisons: + their = other.to_digestable(dns.name.root) + their_relative = True + if _allow_relative_comparisons: + if our_relative != their_relative: + # For the purpose of comparison, all rdata with at least one + # relative name is less than an rdata with only absolute names. + if our_relative: + return -1 + else: + return 1 + elif our_relative or their_relative: + raise NoRelativeRdataOrdering + if our == their: + return 0 + elif our > their: + return 1 + else: + return -1 + + def __eq__(self, other): + if not isinstance(other, Rdata): + return False + if self.rdclass != other.rdclass or self.rdtype != other.rdtype: + return False + our_relative = False + their_relative = False + try: + our = self.to_digestable() + except dns.name.NeedAbsoluteNameOrOrigin: + our = self.to_digestable(dns.name.root) + our_relative = True + try: + their = other.to_digestable() + except dns.name.NeedAbsoluteNameOrOrigin: + their = other.to_digestable(dns.name.root) + their_relative = True + if our_relative != their_relative: + return False + return our == their + + def __ne__(self, other): + if not isinstance(other, Rdata): + return True + if self.rdclass != other.rdclass or self.rdtype != other.rdtype: + return True + return not self.__eq__(other) + + def __lt__(self, other): + if ( + not isinstance(other, Rdata) + or self.rdclass != other.rdclass + or self.rdtype != other.rdtype + ): + return NotImplemented + return self._cmp(other) < 0 + + def __le__(self, other): + if ( + not isinstance(other, Rdata) + or self.rdclass != other.rdclass + or self.rdtype != other.rdtype + ): + return NotImplemented + return self._cmp(other) <= 0 + + def __ge__(self, other): + if ( + not isinstance(other, Rdata) + or self.rdclass != other.rdclass + or self.rdtype != other.rdtype + ): + return NotImplemented + return self._cmp(other) >= 0 + + def __gt__(self, other): + if ( + not isinstance(other, Rdata) + or self.rdclass != other.rdclass + or self.rdtype != other.rdtype + ): + return NotImplemented + return self._cmp(other) > 0 + + def __hash__(self): + return hash(self.to_digestable(dns.name.root)) + + @classmethod + def from_text( + cls, + rdclass: dns.rdataclass.RdataClass, + rdtype: dns.rdatatype.RdataType, + tok: dns.tokenizer.Tokenizer, + origin: Optional[dns.name.Name] = None, + relativize: bool = True, + relativize_to: Optional[dns.name.Name] = None, + ) -> "Rdata": + raise NotImplementedError # pragma: no cover + + @classmethod + def from_wire_parser( + cls, + rdclass: dns.rdataclass.RdataClass, + rdtype: dns.rdatatype.RdataType, + parser: dns.wire.Parser, + origin: Optional[dns.name.Name] = None, + ) -> "Rdata": + raise NotImplementedError # pragma: no cover + + def replace(self, **kwargs: Any) -> "Rdata": + """ + Create a new Rdata instance based on the instance replace was + invoked on. It is possible to pass different parameters to + override the corresponding properties of the base Rdata. + + Any field specific to the Rdata type can be replaced, but the + *rdtype* and *rdclass* fields cannot. + + Returns an instance of the same Rdata subclass as *self*. + """ + + # Get the constructor parameters. + parameters = inspect.signature(self.__init__).parameters # type: ignore + + # Ensure that all of the arguments correspond to valid fields. + # Don't allow rdclass or rdtype to be changed, though. + for key in kwargs: + if key == "rdcomment": + continue + if key not in parameters: + raise AttributeError( + f"'{self.__class__.__name__}' object has no attribute '{key}'" + ) + if key in ("rdclass", "rdtype"): + raise AttributeError( + f"Cannot overwrite '{self.__class__.__name__}' attribute '{key}'" + ) + + # Construct the parameter list. For each field, use the value in + # kwargs if present, and the current value otherwise. + args = (kwargs.get(key, getattr(self, key)) for key in parameters) + + # Create, validate, and return the new object. + rd = self.__class__(*args) + # The comment is not set in the constructor, so give it special + # handling. + rdcomment = kwargs.get("rdcomment", self.rdcomment) + if rdcomment is not None: + object.__setattr__(rd, "rdcomment", rdcomment) + return rd + + # Type checking and conversion helpers. These are class methods as + # they don't touch object state and may be useful to others. + + @classmethod + def _as_rdataclass(cls, value): + return dns.rdataclass.RdataClass.make(value) + + @classmethod + def _as_rdatatype(cls, value): + return dns.rdatatype.RdataType.make(value) + + @classmethod + def _as_bytes( + cls, + value: Any, + encode: bool = False, + max_length: Optional[int] = None, + empty_ok: bool = True, + ) -> bytes: + if encode and isinstance(value, str): + bvalue = value.encode() + elif isinstance(value, bytearray): + bvalue = bytes(value) + elif isinstance(value, bytes): + bvalue = value + else: + raise ValueError("not bytes") + if max_length is not None and len(bvalue) > max_length: + raise ValueError("too long") + if not empty_ok and len(bvalue) == 0: + raise ValueError("empty bytes not allowed") + return bvalue + + @classmethod + def _as_name(cls, value): + # Note that proper name conversion (e.g. with origin and IDNA + # awareness) is expected to be done via from_text. This is just + # a simple thing for people invoking the constructor directly. + if isinstance(value, str): + return dns.name.from_text(value) + elif not isinstance(value, dns.name.Name): + raise ValueError("not a name") + return value + + @classmethod + def _as_uint8(cls, value): + if not isinstance(value, int): + raise ValueError("not an integer") + if value < 0 or value > 255: + raise ValueError("not a uint8") + return value + + @classmethod + def _as_uint16(cls, value): + if not isinstance(value, int): + raise ValueError("not an integer") + if value < 0 or value > 65535: + raise ValueError("not a uint16") + return value + + @classmethod + def _as_uint32(cls, value): + if not isinstance(value, int): + raise ValueError("not an integer") + if value < 0 or value > 4294967295: + raise ValueError("not a uint32") + return value + + @classmethod + def _as_uint48(cls, value): + if not isinstance(value, int): + raise ValueError("not an integer") + if value < 0 or value > 281474976710655: + raise ValueError("not a uint48") + return value + + @classmethod + def _as_int(cls, value, low=None, high=None): + if not isinstance(value, int): + raise ValueError("not an integer") + if low is not None and value < low: + raise ValueError("value too small") + if high is not None and value > high: + raise ValueError("value too large") + return value + + @classmethod + def _as_ipv4_address(cls, value): + if isinstance(value, str): + return dns.ipv4.canonicalize(value) + elif isinstance(value, bytes): + return dns.ipv4.inet_ntoa(value) + else: + raise ValueError("not an IPv4 address") + + @classmethod + def _as_ipv6_address(cls, value): + if isinstance(value, str): + return dns.ipv6.canonicalize(value) + elif isinstance(value, bytes): + return dns.ipv6.inet_ntoa(value) + else: + raise ValueError("not an IPv6 address") + + @classmethod + def _as_bool(cls, value): + if isinstance(value, bool): + return value + else: + raise ValueError("not a boolean") + + @classmethod + def _as_ttl(cls, value): + if isinstance(value, int): + return cls._as_int(value, 0, dns.ttl.MAX_TTL) + elif isinstance(value, str): + return dns.ttl.from_text(value) + else: + raise ValueError("not a TTL") + + @classmethod + def _as_tuple(cls, value, as_value): + try: + # For user convenience, if value is a singleton of the list + # element type, wrap it in a tuple. + return (as_value(value),) + except Exception: + # Otherwise, check each element of the iterable *value* + # against *as_value*. + return tuple(as_value(v) for v in value) + + # Processing order + + @classmethod + def _processing_order(cls, iterable): + items = list(iterable) + random.shuffle(items) + return items + + +@dns.immutable.immutable +class GenericRdata(Rdata): + """Generic Rdata Class + + This class is used for rdata types for which we have no better + implementation. It implements the DNS "unknown RRs" scheme. + """ + + __slots__ = ["data"] + + def __init__(self, rdclass, rdtype, data): + super().__init__(rdclass, rdtype) + self.data = data + + def to_text( + self, + origin: Optional[dns.name.Name] = None, + relativize: bool = True, + **kw: Dict[str, Any], + ) -> str: + return r"\# %d " % len(self.data) + _hexify(self.data, **kw) + + @classmethod + def from_text( + cls, rdclass, rdtype, tok, origin=None, relativize=True, relativize_to=None + ): + token = tok.get() + if not token.is_identifier() or token.value != r"\#": + raise dns.exception.SyntaxError(r"generic rdata does not start with \#") + length = tok.get_int() + hex = tok.concatenate_remaining_identifiers(True).encode() + data = binascii.unhexlify(hex) + if len(data) != length: + raise dns.exception.SyntaxError("generic rdata hex data has wrong length") + return cls(rdclass, rdtype, data) + + def _to_wire(self, file, compress=None, origin=None, canonicalize=False): + file.write(self.data) + + @classmethod + def from_wire_parser(cls, rdclass, rdtype, parser, origin=None): + return cls(rdclass, rdtype, parser.get_remaining()) + + +_rdata_classes: Dict[Tuple[dns.rdataclass.RdataClass, dns.rdatatype.RdataType], Any] = ( + {} +) +_module_prefix = "dns.rdtypes" +_dynamic_load_allowed = True + + +def get_rdata_class(rdclass, rdtype, use_generic=True): + cls = _rdata_classes.get((rdclass, rdtype)) + if not cls: + cls = _rdata_classes.get((dns.rdatatype.ANY, rdtype)) + if not cls and _dynamic_load_allowed: + rdclass_text = dns.rdataclass.to_text(rdclass) + rdtype_text = dns.rdatatype.to_text(rdtype) + rdtype_text = rdtype_text.replace("-", "_") + try: + mod = import_module( + ".".join([_module_prefix, rdclass_text, rdtype_text]) + ) + cls = getattr(mod, rdtype_text) + _rdata_classes[(rdclass, rdtype)] = cls + except ImportError: + try: + mod = import_module(".".join([_module_prefix, "ANY", rdtype_text])) + cls = getattr(mod, rdtype_text) + _rdata_classes[(dns.rdataclass.ANY, rdtype)] = cls + _rdata_classes[(rdclass, rdtype)] = cls + except ImportError: + pass + if not cls and use_generic: + cls = GenericRdata + _rdata_classes[(rdclass, rdtype)] = cls + return cls + + +def load_all_types(disable_dynamic_load=True): + """Load all rdata types for which dnspython has a non-generic implementation. + + Normally dnspython loads DNS rdatatype implementations on demand, but in some + specialized cases loading all types at an application-controlled time is preferred. + + If *disable_dynamic_load*, a ``bool``, is ``True`` then dnspython will not attempt + to use its dynamic loading mechanism if an unknown type is subsequently encountered, + and will simply use the ``GenericRdata`` class. + """ + # Load class IN and ANY types. + for rdtype in dns.rdatatype.RdataType: + get_rdata_class(dns.rdataclass.IN, rdtype, False) + # Load the one non-ANY implementation we have in CH. Everything + # else in CH is an ANY type, and we'll discover those on demand but won't + # have to import anything. + get_rdata_class(dns.rdataclass.CH, dns.rdatatype.A, False) + if disable_dynamic_load: + # Now disable dynamic loading so any subsequent unknown type immediately becomes + # GenericRdata without a load attempt. + global _dynamic_load_allowed + _dynamic_load_allowed = False + + +def from_text( + rdclass: Union[dns.rdataclass.RdataClass, str], + rdtype: Union[dns.rdatatype.RdataType, str], + tok: Union[dns.tokenizer.Tokenizer, str], + origin: Optional[dns.name.Name] = None, + relativize: bool = True, + relativize_to: Optional[dns.name.Name] = None, + idna_codec: Optional[dns.name.IDNACodec] = None, +) -> Rdata: + """Build an rdata object from text format. + + This function attempts to dynamically load a class which + implements the specified rdata class and type. If there is no + class-and-type-specific implementation, the GenericRdata class + is used. + + Once a class is chosen, its from_text() class method is called + with the parameters to this function. + + If *tok* is a ``str``, then a tokenizer is created and the string + is used as its input. + + *rdclass*, a ``dns.rdataclass.RdataClass`` or ``str``, the rdataclass. + + *rdtype*, a ``dns.rdatatype.RdataType`` or ``str``, the rdatatype. + + *tok*, a ``dns.tokenizer.Tokenizer`` or a ``str``. + + *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. + + *idna_codec*, a ``dns.name.IDNACodec``, specifies the IDNA + encoder/decoder to use if a tokenizer needs to be created. If + ``None``, the default IDNA 2003 encoder/decoder is used. If a + tokenizer is not created, then the codec associated with the tokenizer + is the one that is used. + + Returns an instance of the chosen Rdata subclass. + + """ + if isinstance(tok, str): + tok = dns.tokenizer.Tokenizer(tok, idna_codec=idna_codec) + rdclass = dns.rdataclass.RdataClass.make(rdclass) + rdtype = dns.rdatatype.RdataType.make(rdtype) + cls = get_rdata_class(rdclass, rdtype) + with dns.exception.ExceptionWrapper(dns.exception.SyntaxError): + rdata = None + if cls != GenericRdata: + # peek at first token + token = tok.get() + tok.unget(token) + if token.is_identifier() and token.value == r"\#": + # + # Known type using the generic syntax. Extract the + # wire form from the generic syntax, and then run + # from_wire on it. + # + grdata = GenericRdata.from_text( + rdclass, rdtype, tok, origin, relativize, relativize_to + ) + rdata = from_wire( + rdclass, rdtype, grdata.data, 0, len(grdata.data), origin + ) + # + # If this comparison isn't equal, then there must have been + # compressed names in the wire format, which is an error, + # there being no reasonable context to decompress with. + # + rwire = rdata.to_wire() + if rwire != grdata.data: + raise dns.exception.SyntaxError( + "compressed data in " + "generic syntax form " + "of known rdatatype" + ) + if rdata is None: + rdata = cls.from_text( + rdclass, rdtype, tok, origin, relativize, relativize_to + ) + token = tok.get_eol_as_token() + if token.comment is not None: + object.__setattr__(rdata, "rdcomment", token.comment) + return rdata + + +def from_wire_parser( + rdclass: Union[dns.rdataclass.RdataClass, str], + rdtype: Union[dns.rdatatype.RdataType, str], + parser: dns.wire.Parser, + origin: Optional[dns.name.Name] = None, +) -> Rdata: + """Build an rdata object from wire format + + This function attempts to dynamically load a class which + implements the specified rdata class and type. If there is no + class-and-type-specific implementation, the GenericRdata class + is used. + + Once a class is chosen, its from_wire() class method is called + with the parameters to this function. + + *rdclass*, a ``dns.rdataclass.RdataClass`` or ``str``, the rdataclass. + + *rdtype*, a ``dns.rdatatype.RdataType`` or ``str``, the rdatatype. + + *parser*, a ``dns.wire.Parser``, the parser, which should be + restricted to the rdata length. + + *origin*, a ``dns.name.Name`` (or ``None``). If not ``None``, + then names will be relativized to this origin. + + Returns an instance of the chosen Rdata subclass. + """ + + rdclass = dns.rdataclass.RdataClass.make(rdclass) + rdtype = dns.rdatatype.RdataType.make(rdtype) + cls = get_rdata_class(rdclass, rdtype) + with dns.exception.ExceptionWrapper(dns.exception.FormError): + return cls.from_wire_parser(rdclass, rdtype, parser, origin) + + +def from_wire( + rdclass: Union[dns.rdataclass.RdataClass, str], + rdtype: Union[dns.rdatatype.RdataType, str], + wire: bytes, + current: int, + rdlen: int, + origin: Optional[dns.name.Name] = None, +) -> Rdata: + """Build an rdata object from wire format + + This function attempts to dynamically load a class which + implements the specified rdata class and type. If there is no + class-and-type-specific implementation, the GenericRdata class + is used. + + Once a class is chosen, its from_wire() class method is called + with the parameters to this function. + + *rdclass*, an ``int``, the rdataclass. + + *rdtype*, an ``int``, the rdatatype. + + *wire*, a ``bytes``, the wire-format message. + + *current*, an ``int``, the offset in wire of the beginning of + the rdata. + + *rdlen*, an ``int``, the length of the wire-format rdata + + *origin*, a ``dns.name.Name`` (or ``None``). If not ``None``, + then names will be relativized to this origin. + + Returns an instance of the chosen Rdata subclass. + """ + parser = dns.wire.Parser(wire, current) + with parser.restrict_to(rdlen): + return from_wire_parser(rdclass, rdtype, parser, origin) + + +class RdatatypeExists(dns.exception.DNSException): + """DNS rdatatype already exists.""" + + supp_kwargs = {"rdclass", "rdtype"} + fmt = ( + "The rdata type with class {rdclass:d} and rdtype {rdtype:d} " + + "already exists." + ) + + +def register_type( + implementation: Any, + rdtype: int, + rdtype_text: str, + is_singleton: bool = False, + rdclass: dns.rdataclass.RdataClass = dns.rdataclass.IN, +) -> None: + """Dynamically register a module to handle an rdatatype. + + *implementation*, a module implementing the type in the usual dnspython + way. + + *rdtype*, an ``int``, the rdatatype to register. + + *rdtype_text*, a ``str``, the textual form of the rdatatype. + + *is_singleton*, a ``bool``, indicating if the type is a singleton (i.e. + RRsets of the type can have only one member.) + + *rdclass*, the rdataclass of the type, or ``dns.rdataclass.ANY`` if + it applies to all classes. + """ + + rdtype = dns.rdatatype.RdataType.make(rdtype) + existing_cls = get_rdata_class(rdclass, rdtype) + if existing_cls != GenericRdata or dns.rdatatype.is_metatype(rdtype): + raise RdatatypeExists(rdclass=rdclass, rdtype=rdtype) + _rdata_classes[(rdclass, rdtype)] = getattr( + implementation, rdtype_text.replace("-", "_") + ) + dns.rdatatype.register_type(rdtype, rdtype_text, is_singleton) |