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Diffstat (limited to '.venv/lib/python3.12/site-packages/dns/name.py')
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diff --git a/.venv/lib/python3.12/site-packages/dns/name.py b/.venv/lib/python3.12/site-packages/dns/name.py new file mode 100644 index 00000000..f79f0d0f --- /dev/null +++ b/.venv/lib/python3.12/site-packages/dns/name.py @@ -0,0 +1,1284 @@ +# 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 Names. +""" + +import copy +import encodings.idna # type: ignore +import functools +import struct +from typing import Any, Callable, Dict, Iterable, Optional, Tuple, Union + +import dns._features +import dns.enum +import dns.exception +import dns.immutable +import dns.wire + +if dns._features.have("idna"): + import idna # type: ignore + + have_idna_2008 = True +else: # pragma: no cover + have_idna_2008 = False + +CompressType = Dict["Name", int] + + +class NameRelation(dns.enum.IntEnum): + """Name relation result from fullcompare().""" + + # This is an IntEnum for backwards compatibility in case anyone + # has hardwired the constants. + + #: The compared names have no relationship to each other. + NONE = 0 + #: the first name is a superdomain of the second. + SUPERDOMAIN = 1 + #: The first name is a subdomain of the second. + SUBDOMAIN = 2 + #: The compared names are equal. + EQUAL = 3 + #: The compared names have a common ancestor. + COMMONANCESTOR = 4 + + @classmethod + def _maximum(cls): + return cls.COMMONANCESTOR # pragma: no cover + + @classmethod + def _short_name(cls): + return cls.__name__ # pragma: no cover + + +# Backwards compatibility +NAMERELN_NONE = NameRelation.NONE +NAMERELN_SUPERDOMAIN = NameRelation.SUPERDOMAIN +NAMERELN_SUBDOMAIN = NameRelation.SUBDOMAIN +NAMERELN_EQUAL = NameRelation.EQUAL +NAMERELN_COMMONANCESTOR = NameRelation.COMMONANCESTOR + + +class EmptyLabel(dns.exception.SyntaxError): + """A DNS label is empty.""" + + +class BadEscape(dns.exception.SyntaxError): + """An escaped code in a text format of DNS name is invalid.""" + + +class BadPointer(dns.exception.FormError): + """A DNS compression pointer points forward instead of backward.""" + + +class BadLabelType(dns.exception.FormError): + """The label type in DNS name wire format is unknown.""" + + +class NeedAbsoluteNameOrOrigin(dns.exception.DNSException): + """An attempt was made to convert a non-absolute name to + wire when there was also a non-absolute (or missing) origin.""" + + +class NameTooLong(dns.exception.FormError): + """A DNS name is > 255 octets long.""" + + +class LabelTooLong(dns.exception.SyntaxError): + """A DNS label is > 63 octets long.""" + + +class AbsoluteConcatenation(dns.exception.DNSException): + """An attempt was made to append anything other than the + empty name to an absolute DNS name.""" + + +class NoParent(dns.exception.DNSException): + """An attempt was made to get the parent of the root name + or the empty name.""" + + +class NoIDNA2008(dns.exception.DNSException): + """IDNA 2008 processing was requested but the idna module is not + available.""" + + +class IDNAException(dns.exception.DNSException): + """IDNA processing raised an exception.""" + + supp_kwargs = {"idna_exception"} + fmt = "IDNA processing exception: {idna_exception}" + + # We do this as otherwise mypy complains about unexpected keyword argument + # idna_exception + def __init__(self, *args, **kwargs): + super().__init__(*args, **kwargs) + + +class NeedSubdomainOfOrigin(dns.exception.DNSException): + """An absolute name was provided that is not a subdomain of the specified origin.""" + + +_escaped = b'"().;\\@$' +_escaped_text = '"().;\\@$' + + +def _escapify(label: Union[bytes, str]) -> str: + """Escape the characters in label which need it. + @returns: the escaped string + @rtype: string""" + if isinstance(label, bytes): + # Ordinary DNS label mode. Escape special characters and values + # < 0x20 or > 0x7f. + text = "" + for c in label: + if c in _escaped: + text += "\\" + chr(c) + elif c > 0x20 and c < 0x7F: + text += chr(c) + else: + text += "\\%03d" % c + return text + + # Unicode label mode. Escape only special characters and values < 0x20 + text = "" + for uc in label: + if uc in _escaped_text: + text += "\\" + uc + elif uc <= "\x20": + text += "\\%03d" % ord(uc) + else: + text += uc + return text + + +class IDNACodec: + """Abstract base class for IDNA encoder/decoders.""" + + def __init__(self): + pass + + def is_idna(self, label: bytes) -> bool: + return label.lower().startswith(b"xn--") + + def encode(self, label: str) -> bytes: + raise NotImplementedError # pragma: no cover + + def decode(self, label: bytes) -> str: + # We do not apply any IDNA policy on decode. + if self.is_idna(label): + try: + slabel = label[4:].decode("punycode") + return _escapify(slabel) + except Exception as e: + raise IDNAException(idna_exception=e) + else: + return _escapify(label) + + +class IDNA2003Codec(IDNACodec): + """IDNA 2003 encoder/decoder.""" + + def __init__(self, strict_decode: bool = False): + """Initialize the IDNA 2003 encoder/decoder. + + *strict_decode* is a ``bool``. If `True`, then IDNA2003 checking + is done when decoding. This can cause failures if the name + was encoded with IDNA2008. The default is `False`. + """ + + super().__init__() + self.strict_decode = strict_decode + + def encode(self, label: str) -> bytes: + """Encode *label*.""" + + if label == "": + return b"" + try: + return encodings.idna.ToASCII(label) + except UnicodeError: + raise LabelTooLong + + def decode(self, label: bytes) -> str: + """Decode *label*.""" + if not self.strict_decode: + return super().decode(label) + if label == b"": + return "" + try: + return _escapify(encodings.idna.ToUnicode(label)) + except Exception as e: + raise IDNAException(idna_exception=e) + + +class IDNA2008Codec(IDNACodec): + """IDNA 2008 encoder/decoder.""" + + def __init__( + self, + uts_46: bool = False, + transitional: bool = False, + allow_pure_ascii: bool = False, + strict_decode: bool = False, + ): + """Initialize the IDNA 2008 encoder/decoder. + + *uts_46* is a ``bool``. If True, apply Unicode IDNA + compatibility processing as described in Unicode Technical + Standard #46 (https://unicode.org/reports/tr46/). + If False, do not apply the mapping. The default is False. + + *transitional* is a ``bool``: If True, use the + "transitional" mode described in Unicode Technical Standard + #46. The default is False. + + *allow_pure_ascii* is a ``bool``. If True, then a label which + consists of only ASCII characters is allowed. This is less + strict than regular IDNA 2008, but is also necessary for mixed + names, e.g. a name with starting with "_sip._tcp." and ending + in an IDN suffix which would otherwise be disallowed. The + default is False. + + *strict_decode* is a ``bool``: If True, then IDNA2008 checking + is done when decoding. This can cause failures if the name + was encoded with IDNA2003. The default is False. + """ + super().__init__() + self.uts_46 = uts_46 + self.transitional = transitional + self.allow_pure_ascii = allow_pure_ascii + self.strict_decode = strict_decode + + def encode(self, label: str) -> bytes: + if label == "": + return b"" + if self.allow_pure_ascii and is_all_ascii(label): + encoded = label.encode("ascii") + if len(encoded) > 63: + raise LabelTooLong + return encoded + if not have_idna_2008: + raise NoIDNA2008 + try: + if self.uts_46: + # pylint: disable=possibly-used-before-assignment + label = idna.uts46_remap(label, False, self.transitional) + return idna.alabel(label) + except idna.IDNAError as e: + if e.args[0] == "Label too long": + raise LabelTooLong + else: + raise IDNAException(idna_exception=e) + + def decode(self, label: bytes) -> str: + if not self.strict_decode: + return super().decode(label) + if label == b"": + return "" + if not have_idna_2008: + raise NoIDNA2008 + try: + ulabel = idna.ulabel(label) + if self.uts_46: + ulabel = idna.uts46_remap(ulabel, False, self.transitional) + return _escapify(ulabel) + except (idna.IDNAError, UnicodeError) as e: + raise IDNAException(idna_exception=e) + + +IDNA_2003_Practical = IDNA2003Codec(False) +IDNA_2003_Strict = IDNA2003Codec(True) +IDNA_2003 = IDNA_2003_Practical +IDNA_2008_Practical = IDNA2008Codec(True, False, True, False) +IDNA_2008_UTS_46 = IDNA2008Codec(True, False, False, False) +IDNA_2008_Strict = IDNA2008Codec(False, False, False, True) +IDNA_2008_Transitional = IDNA2008Codec(True, True, False, False) +IDNA_2008 = IDNA_2008_Practical + + +def _validate_labels(labels: Tuple[bytes, ...]) -> None: + """Check for empty labels in the middle of a label sequence, + labels that are too long, and for too many labels. + + Raises ``dns.name.NameTooLong`` if the name as a whole is too long. + + Raises ``dns.name.EmptyLabel`` if a label is empty (i.e. the root + label) and appears in a position other than the end of the label + sequence + + """ + + l = len(labels) + total = 0 + i = -1 + j = 0 + for label in labels: + ll = len(label) + total += ll + 1 + if ll > 63: + raise LabelTooLong + if i < 0 and label == b"": + i = j + j += 1 + if total > 255: + raise NameTooLong + if i >= 0 and i != l - 1: + raise EmptyLabel + + +def _maybe_convert_to_binary(label: Union[bytes, str]) -> bytes: + """If label is ``str``, convert it to ``bytes``. If it is already + ``bytes`` just return it. + + """ + + if isinstance(label, bytes): + return label + if isinstance(label, str): + return label.encode() + raise ValueError # pragma: no cover + + +@dns.immutable.immutable +class Name: + """A DNS name. + + The dns.name.Name class represents a DNS name as a tuple of + labels. Each label is a ``bytes`` in DNS wire format. Instances + of the class are immutable. + """ + + __slots__ = ["labels"] + + def __init__(self, labels: Iterable[Union[bytes, str]]): + """*labels* is any iterable whose values are ``str`` or ``bytes``.""" + + blabels = [_maybe_convert_to_binary(x) for x in labels] + self.labels = tuple(blabels) + _validate_labels(self.labels) + + def __copy__(self): + return Name(self.labels) + + def __deepcopy__(self, memo): + return Name(copy.deepcopy(self.labels, memo)) + + def __getstate__(self): + # Names can be pickled + return {"labels": self.labels} + + def __setstate__(self, state): + super().__setattr__("labels", state["labels"]) + _validate_labels(self.labels) + + def is_absolute(self) -> bool: + """Is the most significant label of this name the root label? + + Returns a ``bool``. + """ + + return len(self.labels) > 0 and self.labels[-1] == b"" + + def is_wild(self) -> bool: + """Is this name wild? (I.e. Is the least significant label '*'?) + + Returns a ``bool``. + """ + + return len(self.labels) > 0 and self.labels[0] == b"*" + + def __hash__(self) -> int: + """Return a case-insensitive hash of the name. + + Returns an ``int``. + """ + + h = 0 + for label in self.labels: + for c in label.lower(): + h += (h << 3) + c + return h + + def fullcompare(self, other: "Name") -> Tuple[NameRelation, int, int]: + """Compare two names, returning a 3-tuple + ``(relation, order, nlabels)``. + + *relation* describes the relation ship between the names, + and is one of: ``dns.name.NameRelation.NONE``, + ``dns.name.NameRelation.SUPERDOMAIN``, ``dns.name.NameRelation.SUBDOMAIN``, + ``dns.name.NameRelation.EQUAL``, or ``dns.name.NameRelation.COMMONANCESTOR``. + + *order* is < 0 if *self* < *other*, > 0 if *self* > *other*, and == + 0 if *self* == *other*. A relative name is always less than an + absolute name. If both names have the same relativity, then + the DNSSEC order relation is used to order them. + + *nlabels* is the number of significant labels that the two names + have in common. + + Here are some examples. Names ending in "." are absolute names, + those not ending in "." are relative names. + + ============= ============= =========== ===== ======= + self other relation order nlabels + ============= ============= =========== ===== ======= + www.example. www.example. equal 0 3 + www.example. example. subdomain > 0 2 + example. www.example. superdomain < 0 2 + example1.com. example2.com. common anc. < 0 2 + example1 example2. none < 0 0 + example1. example2 none > 0 0 + ============= ============= =========== ===== ======= + """ + + sabs = self.is_absolute() + oabs = other.is_absolute() + if sabs != oabs: + if sabs: + return (NameRelation.NONE, 1, 0) + else: + return (NameRelation.NONE, -1, 0) + l1 = len(self.labels) + l2 = len(other.labels) + ldiff = l1 - l2 + if ldiff < 0: + l = l1 + else: + l = l2 + + order = 0 + nlabels = 0 + namereln = NameRelation.NONE + while l > 0: + l -= 1 + l1 -= 1 + l2 -= 1 + label1 = self.labels[l1].lower() + label2 = other.labels[l2].lower() + if label1 < label2: + order = -1 + if nlabels > 0: + namereln = NameRelation.COMMONANCESTOR + return (namereln, order, nlabels) + elif label1 > label2: + order = 1 + if nlabels > 0: + namereln = NameRelation.COMMONANCESTOR + return (namereln, order, nlabels) + nlabels += 1 + order = ldiff + if ldiff < 0: + namereln = NameRelation.SUPERDOMAIN + elif ldiff > 0: + namereln = NameRelation.SUBDOMAIN + else: + namereln = NameRelation.EQUAL + return (namereln, order, nlabels) + + def is_subdomain(self, other: "Name") -> bool: + """Is self a subdomain of other? + + Note that the notion of subdomain includes equality, e.g. + "dnspython.org" is a subdomain of itself. + + Returns a ``bool``. + """ + + (nr, _, _) = self.fullcompare(other) + if nr == NameRelation.SUBDOMAIN or nr == NameRelation.EQUAL: + return True + return False + + def is_superdomain(self, other: "Name") -> bool: + """Is self a superdomain of other? + + Note that the notion of superdomain includes equality, e.g. + "dnspython.org" is a superdomain of itself. + + Returns a ``bool``. + """ + + (nr, _, _) = self.fullcompare(other) + if nr == NameRelation.SUPERDOMAIN or nr == NameRelation.EQUAL: + return True + return False + + def canonicalize(self) -> "Name": + """Return a name which is equal to the current name, but is in + DNSSEC canonical form. + """ + + return Name([x.lower() for x in self.labels]) + + def __eq__(self, other): + if isinstance(other, Name): + return self.fullcompare(other)[1] == 0 + else: + return False + + def __ne__(self, other): + if isinstance(other, Name): + return self.fullcompare(other)[1] != 0 + else: + return True + + def __lt__(self, other): + if isinstance(other, Name): + return self.fullcompare(other)[1] < 0 + else: + return NotImplemented + + def __le__(self, other): + if isinstance(other, Name): + return self.fullcompare(other)[1] <= 0 + else: + return NotImplemented + + def __ge__(self, other): + if isinstance(other, Name): + return self.fullcompare(other)[1] >= 0 + else: + return NotImplemented + + def __gt__(self, other): + if isinstance(other, Name): + return self.fullcompare(other)[1] > 0 + else: + return NotImplemented + + def __repr__(self): + return "<DNS name " + self.__str__() + ">" + + def __str__(self): + return self.to_text(False) + + def to_text(self, omit_final_dot: bool = False) -> str: + """Convert name to DNS text format. + + *omit_final_dot* is a ``bool``. If True, don't emit the final + dot (denoting the root label) for absolute names. The default + is False. + + Returns a ``str``. + """ + + if len(self.labels) == 0: + return "@" + if len(self.labels) == 1 and self.labels[0] == b"": + return "." + if omit_final_dot and self.is_absolute(): + l = self.labels[:-1] + else: + l = self.labels + s = ".".join(map(_escapify, l)) + return s + + def to_unicode( + self, omit_final_dot: bool = False, idna_codec: Optional[IDNACodec] = None + ) -> str: + """Convert name to Unicode text format. + + IDN ACE labels are converted to Unicode. + + *omit_final_dot* is a ``bool``. If True, don't emit the final + dot (denoting the root label) for absolute names. The default + is False. + *idna_codec* specifies the IDNA encoder/decoder. If None, the + dns.name.IDNA_2003_Practical encoder/decoder is used. + The IDNA_2003_Practical decoder does + not impose any policy, it just decodes punycode, so if you + don't want checking for compliance, you can use this decoder + for IDNA2008 as well. + + Returns a ``str``. + """ + + if len(self.labels) == 0: + return "@" + if len(self.labels) == 1 and self.labels[0] == b"": + return "." + if omit_final_dot and self.is_absolute(): + l = self.labels[:-1] + else: + l = self.labels + if idna_codec is None: + idna_codec = IDNA_2003_Practical + return ".".join([idna_codec.decode(x) for x in l]) + + def to_digestable(self, origin: Optional["Name"] = None) -> bytes: + """Convert name to a format suitable for digesting in hashes. + + The name is canonicalized and converted to uncompressed wire + format. All names in wire format are absolute. If the name + is a relative name, then an origin must be supplied. + + *origin* is a ``dns.name.Name`` or ``None``. If the name is + relative and origin is not ``None``, then origin will be appended + to the name. + + Raises ``dns.name.NeedAbsoluteNameOrOrigin`` if the name is + relative and no origin was provided. + + Returns a ``bytes``. + """ + + digest = self.to_wire(origin=origin, canonicalize=True) + assert digest is not None + return digest + + def to_wire( + self, + file: Optional[Any] = None, + compress: Optional[CompressType] = None, + origin: Optional["Name"] = None, + canonicalize: bool = False, + ) -> Optional[bytes]: + """Convert name to wire format, possibly compressing it. + + *file* is the file where the name is emitted (typically an + io.BytesIO file). If ``None`` (the default), a ``bytes`` + containing the wire name will be returned. + + *compress*, a ``dict``, is the compression table to use. If + ``None`` (the default), names will not be compressed. Note that + the compression code assumes that compression offset 0 is the + start of *file*, and thus compression will not be correct + if this is not the case. + + *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. + + *canonicalize*, a ``bool``, indicates whether the name should + be canonicalized; that is, converted to a format suitable for + digesting in hashes. + + Raises ``dns.name.NeedAbsoluteNameOrOrigin`` if the name is + relative and no origin was provided. + + Returns a ``bytes`` or ``None``. + """ + + if file is None: + out = bytearray() + for label in self.labels: + out.append(len(label)) + if canonicalize: + out += label.lower() + else: + out += label + if not self.is_absolute(): + if origin is None or not origin.is_absolute(): + raise NeedAbsoluteNameOrOrigin + for label in origin.labels: + out.append(len(label)) + if canonicalize: + out += label.lower() + else: + out += label + return bytes(out) + + labels: Iterable[bytes] + if not self.is_absolute(): + if origin is None or not origin.is_absolute(): + raise NeedAbsoluteNameOrOrigin + labels = list(self.labels) + labels.extend(list(origin.labels)) + else: + labels = self.labels + i = 0 + for label in labels: + n = Name(labels[i:]) + i += 1 + if compress is not None: + pos = compress.get(n) + else: + pos = None + if pos is not None: + value = 0xC000 + pos + s = struct.pack("!H", value) + file.write(s) + break + else: + if compress is not None and len(n) > 1: + pos = file.tell() + if pos <= 0x3FFF: + compress[n] = pos + l = len(label) + file.write(struct.pack("!B", l)) + if l > 0: + if canonicalize: + file.write(label.lower()) + else: + file.write(label) + return None + + def __len__(self) -> int: + """The length of the name (in labels). + + Returns an ``int``. + """ + + return len(self.labels) + + def __getitem__(self, index): + return self.labels[index] + + def __add__(self, other): + return self.concatenate(other) + + def __sub__(self, other): + return self.relativize(other) + + def split(self, depth: int) -> Tuple["Name", "Name"]: + """Split a name into a prefix and suffix names at the specified depth. + + *depth* is an ``int`` specifying the number of labels in the suffix + + Raises ``ValueError`` if *depth* was not >= 0 and <= the length of the + name. + + Returns the tuple ``(prefix, suffix)``. + """ + + l = len(self.labels) + if depth == 0: + return (self, dns.name.empty) + elif depth == l: + return (dns.name.empty, self) + elif depth < 0 or depth > l: + raise ValueError("depth must be >= 0 and <= the length of the name") + return (Name(self[:-depth]), Name(self[-depth:])) + + def concatenate(self, other: "Name") -> "Name": + """Return a new name which is the concatenation of self and other. + + Raises ``dns.name.AbsoluteConcatenation`` if the name is + absolute and *other* is not the empty name. + + Returns a ``dns.name.Name``. + """ + + if self.is_absolute() and len(other) > 0: + raise AbsoluteConcatenation + labels = list(self.labels) + labels.extend(list(other.labels)) + return Name(labels) + + def relativize(self, origin: "Name") -> "Name": + """If the name is a subdomain of *origin*, return a new name which is + the name relative to origin. Otherwise return the name. + + For example, relativizing ``www.dnspython.org.`` to origin + ``dnspython.org.`` returns the name ``www``. Relativizing ``example.`` + to origin ``dnspython.org.`` returns ``example.``. + + Returns a ``dns.name.Name``. + """ + + if origin is not None and self.is_subdomain(origin): + return Name(self[: -len(origin)]) + else: + return self + + def derelativize(self, origin: "Name") -> "Name": + """If the name is a relative name, return a new name which is the + concatenation of the name and origin. Otherwise return the name. + + For example, derelativizing ``www`` to origin ``dnspython.org.`` + returns the name ``www.dnspython.org.``. Derelativizing ``example.`` + to origin ``dnspython.org.`` returns ``example.``. + + Returns a ``dns.name.Name``. + """ + + if not self.is_absolute(): + return self.concatenate(origin) + else: + return self + + def choose_relativity( + self, origin: Optional["Name"] = None, relativize: bool = True + ) -> "Name": + """Return a name with the relativity desired by the caller. + + If *origin* is ``None``, then the name is returned. + Otherwise, if *relativize* is ``True`` the name is + relativized, and if *relativize* is ``False`` the name is + derelativized. + + Returns a ``dns.name.Name``. + """ + + if origin: + if relativize: + return self.relativize(origin) + else: + return self.derelativize(origin) + else: + return self + + def parent(self) -> "Name": + """Return the parent of the name. + + For example, the parent of ``www.dnspython.org.`` is ``dnspython.org``. + + Raises ``dns.name.NoParent`` if the name is either the root name or the + empty name, and thus has no parent. + + Returns a ``dns.name.Name``. + """ + + if self == root or self == empty: + raise NoParent + return Name(self.labels[1:]) + + def predecessor(self, origin: "Name", prefix_ok: bool = True) -> "Name": + """Return the maximal predecessor of *name* in the DNSSEC ordering in the zone + whose origin is *origin*, or return the longest name under *origin* if the + name is origin (i.e. wrap around to the longest name, which may still be + *origin* due to length considerations. + + The relativity of the name is preserved, so if this name is relative + then the method will return a relative name, and likewise if this name + is absolute then the predecessor will be absolute. + + *prefix_ok* indicates if prefixing labels is allowed, and + defaults to ``True``. Normally it is good to allow this, but if computing + a maximal predecessor at a zone cut point then ``False`` must be specified. + """ + return _handle_relativity_and_call( + _absolute_predecessor, self, origin, prefix_ok + ) + + def successor(self, origin: "Name", prefix_ok: bool = True) -> "Name": + """Return the minimal successor of *name* in the DNSSEC ordering in the zone + whose origin is *origin*, or return *origin* if the successor cannot be + computed due to name length limitations. + + Note that *origin* is returned in the "too long" cases because wrapping + around to the origin is how NSEC records express "end of the zone". + + The relativity of the name is preserved, so if this name is relative + then the method will return a relative name, and likewise if this name + is absolute then the successor will be absolute. + + *prefix_ok* indicates if prefixing a new minimal label is allowed, and + defaults to ``True``. Normally it is good to allow this, but if computing + a minimal successor at a zone cut point then ``False`` must be specified. + """ + return _handle_relativity_and_call(_absolute_successor, self, origin, prefix_ok) + + +#: The root name, '.' +root = Name([b""]) + +#: The empty name. +empty = Name([]) + + +def from_unicode( + text: str, origin: Optional[Name] = root, idna_codec: Optional[IDNACodec] = None +) -> Name: + """Convert unicode text into a Name object. + + Labels are encoded in IDN ACE form according to rules specified by + the IDNA codec. + + *text*, a ``str``, is the text to convert into a name. + + *origin*, a ``dns.name.Name``, specifies the origin to + append to non-absolute names. The default is the root name. + + *idna_codec*, a ``dns.name.IDNACodec``, specifies the IDNA + encoder/decoder. If ``None``, the default IDNA 2003 encoder/decoder + is used. + + Returns a ``dns.name.Name``. + """ + + if not isinstance(text, str): + raise ValueError("input to from_unicode() must be a unicode string") + if not (origin is None or isinstance(origin, Name)): + raise ValueError("origin must be a Name or None") + labels = [] + label = "" + escaping = False + edigits = 0 + total = 0 + if idna_codec is None: + idna_codec = IDNA_2003 + if text == "@": + text = "" + if text: + if text in [".", "\u3002", "\uff0e", "\uff61"]: + return Name([b""]) # no Unicode "u" on this constant! + for c in text: + if escaping: + if edigits == 0: + if c.isdigit(): + total = int(c) + edigits += 1 + else: + label += c + escaping = False + else: + if not c.isdigit(): + raise BadEscape + total *= 10 + total += int(c) + edigits += 1 + if edigits == 3: + escaping = False + label += chr(total) + elif c in [".", "\u3002", "\uff0e", "\uff61"]: + if len(label) == 0: + raise EmptyLabel + labels.append(idna_codec.encode(label)) + label = "" + elif c == "\\": + escaping = True + edigits = 0 + total = 0 + else: + label += c + if escaping: + raise BadEscape + if len(label) > 0: + labels.append(idna_codec.encode(label)) + else: + labels.append(b"") + + if (len(labels) == 0 or labels[-1] != b"") and origin is not None: + labels.extend(list(origin.labels)) + return Name(labels) + + +def is_all_ascii(text: str) -> bool: + for c in text: + if ord(c) > 0x7F: + return False + return True + + +def from_text( + text: Union[bytes, str], + origin: Optional[Name] = root, + idna_codec: Optional[IDNACodec] = None, +) -> Name: + """Convert text into a Name object. + + *text*, a ``bytes`` or ``str``, is the text to convert into a name. + + *origin*, a ``dns.name.Name``, specifies the origin to + append to non-absolute names. The default is the root name. + + *idna_codec*, a ``dns.name.IDNACodec``, specifies the IDNA + encoder/decoder. If ``None``, the default IDNA 2003 encoder/decoder + is used. + + Returns a ``dns.name.Name``. + """ + + if isinstance(text, str): + if not is_all_ascii(text): + # Some codepoint in the input text is > 127, so IDNA applies. + return from_unicode(text, origin, idna_codec) + # The input is all ASCII, so treat this like an ordinary non-IDNA + # domain name. Note that "all ASCII" is about the input text, + # not the codepoints in the domain name. E.g. if text has value + # + # r'\150\151\152\153\154\155\156\157\158\159' + # + # then it's still "all ASCII" even though the domain name has + # codepoints > 127. + text = text.encode("ascii") + if not isinstance(text, bytes): + raise ValueError("input to from_text() must be a string") + if not (origin is None or isinstance(origin, Name)): + raise ValueError("origin must be a Name or None") + labels = [] + label = b"" + escaping = False + edigits = 0 + total = 0 + if text == b"@": + text = b"" + if text: + if text == b".": + return Name([b""]) + for c in text: + byte_ = struct.pack("!B", c) + if escaping: + if edigits == 0: + if byte_.isdigit(): + total = int(byte_) + edigits += 1 + else: + label += byte_ + escaping = False + else: + if not byte_.isdigit(): + raise BadEscape + total *= 10 + total += int(byte_) + edigits += 1 + if edigits == 3: + escaping = False + label += struct.pack("!B", total) + elif byte_ == b".": + if len(label) == 0: + raise EmptyLabel + labels.append(label) + label = b"" + elif byte_ == b"\\": + escaping = True + edigits = 0 + total = 0 + else: + label += byte_ + if escaping: + raise BadEscape + if len(label) > 0: + labels.append(label) + else: + labels.append(b"") + if (len(labels) == 0 or labels[-1] != b"") and origin is not None: + labels.extend(list(origin.labels)) + return Name(labels) + + +# we need 'dns.wire.Parser' quoted as dns.name and dns.wire depend on each other. + + +def from_wire_parser(parser: "dns.wire.Parser") -> Name: + """Convert possibly compressed wire format into a Name. + + *parser* is a dns.wire.Parser. + + Raises ``dns.name.BadPointer`` if a compression pointer did not + point backwards in the message. + + Raises ``dns.name.BadLabelType`` if an invalid label type was encountered. + + Returns a ``dns.name.Name`` + """ + + labels = [] + biggest_pointer = parser.current + with parser.restore_furthest(): + count = parser.get_uint8() + while count != 0: + if count < 64: + labels.append(parser.get_bytes(count)) + elif count >= 192: + current = (count & 0x3F) * 256 + parser.get_uint8() + if current >= biggest_pointer: + raise BadPointer + biggest_pointer = current + parser.seek(current) + else: + raise BadLabelType + count = parser.get_uint8() + labels.append(b"") + return Name(labels) + + +def from_wire(message: bytes, current: int) -> Tuple[Name, int]: + """Convert possibly compressed wire format into a Name. + + *message* is a ``bytes`` containing an entire DNS message in DNS + wire form. + + *current*, an ``int``, is the offset of the beginning of the name + from the start of the message + + Raises ``dns.name.BadPointer`` if a compression pointer did not + point backwards in the message. + + Raises ``dns.name.BadLabelType`` if an invalid label type was encountered. + + Returns a ``(dns.name.Name, int)`` tuple consisting of the name + that was read and the number of bytes of the wire format message + which were consumed reading it. + """ + + if not isinstance(message, bytes): + raise ValueError("input to from_wire() must be a byte string") + parser = dns.wire.Parser(message, current) + name = from_wire_parser(parser) + return (name, parser.current - current) + + +# RFC 4471 Support + +_MINIMAL_OCTET = b"\x00" +_MINIMAL_OCTET_VALUE = ord(_MINIMAL_OCTET) +_SUCCESSOR_PREFIX = Name([_MINIMAL_OCTET]) +_MAXIMAL_OCTET = b"\xff" +_MAXIMAL_OCTET_VALUE = ord(_MAXIMAL_OCTET) +_AT_SIGN_VALUE = ord("@") +_LEFT_SQUARE_BRACKET_VALUE = ord("[") + + +def _wire_length(labels): + return functools.reduce(lambda v, x: v + len(x) + 1, labels, 0) + + +def _pad_to_max_name(name): + needed = 255 - _wire_length(name.labels) + new_labels = [] + while needed > 64: + new_labels.append(_MAXIMAL_OCTET * 63) + needed -= 64 + if needed >= 2: + new_labels.append(_MAXIMAL_OCTET * (needed - 1)) + # Note we're already maximal in the needed == 1 case as while we'd like + # to add one more byte as a new label, we can't, as adding a new non-empty + # label requires at least 2 bytes. + new_labels = list(reversed(new_labels)) + new_labels.extend(name.labels) + return Name(new_labels) + + +def _pad_to_max_label(label, suffix_labels): + length = len(label) + # We have to subtract one here to account for the length byte of label. + remaining = 255 - _wire_length(suffix_labels) - length - 1 + if remaining <= 0: + # Shouldn't happen! + return label + needed = min(63 - length, remaining) + return label + _MAXIMAL_OCTET * needed + + +def _absolute_predecessor(name: Name, origin: Name, prefix_ok: bool) -> Name: + # This is the RFC 4471 predecessor algorithm using the "absolute method" of section + # 3.1.1. + # + # Our caller must ensure that the name and origin are absolute, and that name is a + # subdomain of origin. + if name == origin: + return _pad_to_max_name(name) + least_significant_label = name[0] + if least_significant_label == _MINIMAL_OCTET: + return name.parent() + least_octet = least_significant_label[-1] + suffix_labels = name.labels[1:] + if least_octet == _MINIMAL_OCTET_VALUE: + new_labels = [least_significant_label[:-1]] + else: + octets = bytearray(least_significant_label) + octet = octets[-1] + if octet == _LEFT_SQUARE_BRACKET_VALUE: + octet = _AT_SIGN_VALUE + else: + octet -= 1 + octets[-1] = octet + least_significant_label = bytes(octets) + new_labels = [_pad_to_max_label(least_significant_label, suffix_labels)] + new_labels.extend(suffix_labels) + name = Name(new_labels) + if prefix_ok: + return _pad_to_max_name(name) + else: + return name + + +def _absolute_successor(name: Name, origin: Name, prefix_ok: bool) -> Name: + # This is the RFC 4471 successor algorithm using the "absolute method" of section + # 3.1.2. + # + # Our caller must ensure that the name and origin are absolute, and that name is a + # subdomain of origin. + if prefix_ok: + # Try prefixing \000 as new label + try: + return _SUCCESSOR_PREFIX.concatenate(name) + except NameTooLong: + pass + while name != origin: + # Try extending the least significant label. + least_significant_label = name[0] + if len(least_significant_label) < 63: + # We may be able to extend the least label with a minimal additional byte. + # This is only "may" because we could have a maximal length name even though + # the least significant label isn't maximally long. + new_labels = [least_significant_label + _MINIMAL_OCTET] + new_labels.extend(name.labels[1:]) + try: + return dns.name.Name(new_labels) + except dns.name.NameTooLong: + pass + # We can't extend the label either, so we'll try to increment the least + # signficant non-maximal byte in it. + octets = bytearray(least_significant_label) + # We do this reversed iteration with an explicit indexing variable because + # if we find something to increment, we're going to want to truncate everything + # to the right of it. + for i in range(len(octets) - 1, -1, -1): + octet = octets[i] + if octet == _MAXIMAL_OCTET_VALUE: + # We can't increment this, so keep looking. + continue + # Finally, something we can increment. We have to apply a special rule for + # incrementing "@", sending it to "[", because RFC 4034 6.1 says that when + # comparing names, uppercase letters compare as if they were their + # lower-case equivalents. If we increment "@" to "A", then it would compare + # as "a", which is after "[", "\", "]", "^", "_", and "`", so we would have + # skipped the most minimal successor, namely "[". + if octet == _AT_SIGN_VALUE: + octet = _LEFT_SQUARE_BRACKET_VALUE + else: + octet += 1 + octets[i] = octet + # We can now truncate all of the maximal values we skipped (if any) + new_labels = [bytes(octets[: i + 1])] + new_labels.extend(name.labels[1:]) + # We haven't changed the length of the name, so the Name constructor will + # always work. + return Name(new_labels) + # We couldn't increment, so chop off the least significant label and try + # again. + name = name.parent() + + # We couldn't increment at all, so return the origin, as wrapping around is the + # DNSSEC way. + return origin + + +def _handle_relativity_and_call( + function: Callable[[Name, Name, bool], Name], + name: Name, + origin: Name, + prefix_ok: bool, +) -> Name: + # Make "name" absolute if needed, ensure that the origin is absolute, + # call function(), and then relativize the result if needed. + if not origin.is_absolute(): + raise NeedAbsoluteNameOrOrigin + relative = not name.is_absolute() + if relative: + name = name.derelativize(origin) + elif not name.is_subdomain(origin): + raise NeedSubdomainOfOrigin + result_name = function(name, origin, prefix_ok) + if relative: + result_name = result_name.relativize(origin) + return result_name |