# Copyright (C) 2001-2007, 2009-2011 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. @var root: The DNS root name. @type root: dns.name.Name object @var empty: The empty DNS name. @type empty: dns.name.Name object """ from io import BytesIO import struct import sys import copy import encodings.idna try: import idna have_idna_2008 = True except ImportError: have_idna_2008 = False import dns.exception import dns.wiredata from ._compat import long, binary_type, text_type, unichr, maybe_decode try: maxint = sys.maxint except AttributeError: maxint = (1 << (8 * struct.calcsize("P"))) // 2 - 1 NAMERELN_NONE = 0 NAMERELN_SUPERDOMAIN = 1 NAMERELN_SUBDOMAIN = 2 NAMERELN_EQUAL = 3 NAMERELN_COMMONANCESTOR = 4 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 = set(['idna_exception']) fmt = "IDNA processing exception: {idna_exception}" class IDNACodec(object): """Abstract base class for IDNA encoder/decoders.""" def __init__(self): pass def is_idna(self, label): return label.lower().startswith(b'xn--') def is_all_ascii(self, label): for c in label: if ord(c) > 0x7f: return False return True def encode(self, label): raise NotImplementedError def decode(self, label): # We do not apply any IDNA policy on decode. if self.is_idna(label): try: label = label[4:].decode('punycode') except Exception as e: raise IDNAException(idna_exception=e) else: label = maybe_decode(label) return _escapify(label) class IDNA2003Codec(IDNACodec): """IDNA 2003 encoder/decoder.""" def __init__(self, strict_decode=False): """Initialize the IDNA 2003 encoder/decoder. @param strict_decode: If True, then IDNA2003 checking is done when decoding. This can cause failures if the name was encoded with IDNA2008. The default is False. @type strict_decode: bool """ super(IDNA2003Codec, self).__init__() self.strict_decode = strict_decode def encode(self, label): if label == '': return b'' try: return encodings.idna.ToASCII(label) except UnicodeError: raise LabelTooLong def decode(self, label): if not self.strict_decode: return super(IDNA2003Codec, self).decode(label) if label == b'': return u'' 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=False, transitional=False, allow_pure_ascii=False, strict_decode=False): """Initialize the IDNA 2008 encoder/decoder. @param uts_46: If True, apply Unicode IDNA compatibility processing as described in Unicode Technical Standard #46 (U{http://unicode.org/reports/tr46/}). This parameter is only meaningful if IDNA 2008 is in use. If False, do not apply the mapping. The default is False @type uts_46: bool @param transitional: If True, use the "transitional" mode described in Unicode Technical Standard #46. This parameter is only meaningful if IDNA 2008 is in use. The default is False. @type transitional: bool @param allow_pure_ascii: 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 suffixm which would otherwise be disallowed. The default is False @type allow_pure_ascii: bool @param strict_decode: If True, then IDNA2008 checking is done when decoding. This can cause failures if the name was encoded with IDNA2003. The default is False. @type strict_decode: bool """ super(IDNA2008Codec, self).__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): if label == '': return b'' if self.allow_pure_ascii and self.is_all_ascii(label): return label.encode('ascii') if not have_idna_2008: raise NoIDNA2008 try: if self.uts_46: label = idna.uts46_remap(label, False, self.transitional) return idna.alabel(label) except idna.IDNAError as e: raise IDNAException(idna_exception=e) def decode(self, label): if not self.strict_decode: return super(IDNA2008Codec, self).decode(label) if label == b'': return u'' if not have_idna_2008: raise NoIDNA2008 try: if self.uts_46: label = idna.uts46_remap(label, False, False) return _escapify(idna.ulabel(label)) except idna.IDNAError as e: raise IDNAException(idna_exception=e) _escaped = bytearray(b'"().;\\@$') _escaped_text = '"().;\\@$' 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 _escapify(label): """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 = '' if isinstance(label, text_type): label = label.encode() for c in bytearray(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 = u'' for c in label: if c in _escaped_text: text += '\\' + c elif c <= '\x20': text += '\\%03d' % ord(c) else: text += c return text def _validate_labels(labels): """Check for empty labels in the middle of a label sequence, labels that are too long, and for too many labels. @raises NameTooLong: the name as a whole is too long @raises EmptyLabel: 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 _ensure_bytes(label): if isinstance(label, binary_type): return label if isinstance(label, text_type): return label.encode() raise ValueError class Name(object): """A DNS name. The dns.name.Name class represents a DNS name as a tuple of labels. Instances of the class are immutable. @ivar labels: The tuple of labels in the name. Each label is a string of up to 63 octets.""" __slots__ = ['labels'] def __init__(self, labels): """Initialize a domain name from a list of labels. @param labels: the labels @type labels: any iterable whose values are strings """ labels = [_ensure_bytes(x) for x in labels] super(Name, self).__setattr__('labels', tuple(labels)) _validate_labels(self.labels) def __setattr__(self, name, value): raise TypeError("object doesn't support attribute assignment") def __copy__(self): return Name(self.labels) def __deepcopy__(self, memo): return Name(copy.deepcopy(self.labels, memo)) def __getstate__(self): return {'labels': self.labels} def __setstate__(self, state): super(Name, self).__setattr__('labels', state['labels']) _validate_labels(self.labels) def is_absolute(self): """Is the most significant label of this name the root label? @rtype: bool """ return len(self.labels) > 0 and self.labels[-1] == b'' def is_wild(self): """Is this name wild? (I.e. Is the least significant label '*'?) @rtype: bool """ return len(self.labels) > 0 and self.labels[0] == b'*' def __hash__(self): """Return a case-insensitive hash of the name. @rtype: int """ h = long(0) for label in self.labels: for c in bytearray(label.lower()): h += (h << 3) + c return int(h % maxint) def fullcompare(self, other): """Compare two names, returning a 3-tuple (relation, order, nlabels). I{relation} describes the relation ship between the names, and is one of: dns.name.NAMERELN_NONE, dns.name.NAMERELN_SUPERDOMAIN, dns.name.NAMERELN_SUBDOMAIN, dns.name.NAMERELN_EQUAL, or dns.name.NAMERELN_COMMONANCESTOR I{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. I{nlabels} is the number of significant labels that the two names have in common. """ sabs = self.is_absolute() oabs = other.is_absolute() if sabs != oabs: if sabs: return (NAMERELN_NONE, 1, 0) else: return (NAMERELN_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 = NAMERELN_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 = NAMERELN_COMMONANCESTOR return (namereln, order, nlabels) elif label1 > label2: order = 1 if nlabels > 0: namereln = NAMERELN_COMMONANCESTOR return (namereln, order, nlabels) nlabels += 1 order = ldiff if ldiff < 0: namereln = NAMERELN_SUPERDOMAIN elif ldiff > 0: namereln = NAMERELN_SUBDOMAIN else: namereln = NAMERELN_EQUAL return (namereln, order, nlabels) def is_subdomain(self, other): """Is self a subdomain of other? The notion of subdomain includes equality. @rtype: bool """ (nr, o, nl) = self.fullcompare(other) if nr == NAMERELN_SUBDOMAIN or nr == NAMERELN_EQUAL: return True return False def is_superdomain(self, other): """Is self a superdomain of other? The notion of subdomain includes equality. @rtype: bool """ (nr, o, nl) = self.fullcompare(other) if nr == NAMERELN_SUPERDOMAIN or nr == NAMERELN_EQUAL: return True return False def canonicalize(self): """Return a name which is equal to the current name, but is in DNSSEC canonical form. @rtype: dns.name.Name object """ 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 '' def __str__(self): return self.to_text(False) def to_text(self, omit_final_dot=False): """Convert name to text format. @param omit_final_dot: If True, don't emit the final dot (denoting the root label) for absolute names. The default is False. @rtype: string """ if len(self.labels) == 0: return maybe_decode(b'@') if len(self.labels) == 1 and self.labels[0] == b'': return maybe_decode(b'.') 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=False, idna_codec=None): """Convert name to Unicode text format. IDN ACE labels are converted to Unicode. @param omit_final_dot: If True, don't emit the final dot (denoting the root label) for absolute names. The default is False. @type omit_final_dot: bool @param idna_codec: IDNA encoder/decoder. If None, the 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. @type idna_codec: dns.name.IDNA @rtype: string """ if len(self.labels) == 0: return u'@' if len(self.labels) == 1 and self.labels[0] == b'': return u'.' 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 u'.'.join([idna_codec.decode(x) for x in l]) def to_digestable(self, origin=None): """Convert name to a format suitable for digesting in hashes. The name is canonicalized and converted to uncompressed wire format. @param origin: If the name is relative and origin is not None, then origin will be appended to it. @type origin: dns.name.Name object @raises NeedAbsoluteNameOrOrigin: All names in wire format are absolute. If self is a relative name, then an origin must be supplied; if it is missing, then this exception is raised @rtype: string """ 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 dlabels = [struct.pack('!B%ds' % len(x), len(x), x.lower()) for x in labels] return b''.join(dlabels) def to_wire(self, file=None, compress=None, origin=None): """Convert name to wire format, possibly compressing it. @param file: the file where the name is emitted (typically a BytesIO file). If None, a string containing the wire name will be returned. @type file: file or None @param compress: The compression table. If None (the default) names will not be compressed. @type compress: dict @param origin: If the name is relative and origin is not None, then origin will be appended to it. @type origin: dns.name.Name object @raises NeedAbsoluteNameOrOrigin: All names in wire format are absolute. If self is a relative name, then an origin must be supplied; if it is missing, then this exception is raised """ if file is None: file = BytesIO() want_return = True else: want_return = False 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: file.write(label) if want_return: return file.getvalue() def __len__(self): """The length of the name (in labels). @rtype: 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): """Split a name into a prefix and suffix at depth. @param depth: the number of labels in the suffix @type depth: int @raises ValueError: the depth was not >= 0 and <= the length of the name. @returns: the tuple (prefix, suffix) @rtype: tuple """ 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): """Return a new name which is the concatenation of self and other. @rtype: dns.name.Name object @raises AbsoluteConcatenation: self is absolute and other is not the empty 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): """If self is a subdomain of origin, return a new name which is self relative to origin. Otherwise return self. @rtype: dns.name.Name object """ if origin is not None and self.is_subdomain(origin): return Name(self[: -len(origin)]) else: return self def derelativize(self, origin): """If self is a relative name, return a new name which is the concatenation of self and origin. Otherwise return self. @rtype: dns.name.Name object """ if not self.is_absolute(): return self.concatenate(origin) else: return self def choose_relativity(self, origin=None, relativize=True): """Return a name with the relativity desired by the caller. If origin is None, then self is returned. Otherwise, if relativize is true the name is relativized, and if relativize is false the name is derelativized. @rtype: dns.name.Name object """ if origin: if relativize: return self.relativize(origin) else: return self.derelativize(origin) else: return self def parent(self): """Return the parent of the name. @rtype: dns.name.Name object @raises NoParent: the name is either the root name or the empty name, and thus has no parent. """ if self == root or self == empty: raise NoParent return Name(self.labels[1:]) root = Name([b'']) empty = Name([]) def from_unicode(text, origin=root, idna_codec=None): """Convert unicode text into a Name object. Labels are encoded in IDN ACE form. @param text: The text to convert into a name. @type text: Unicode string @param origin: The origin to append to non-absolute names. @type origin: dns.name.Name @param idna_codec: IDNA encoder/decoder. If None, the default IDNA 2003 encoder/decoder is used. @type idna_codec: dns.name.IDNA @rtype: dns.name.Name object """ if not isinstance(text, text_type): 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 = u'' escaping = False edigits = 0 total = 0 if idna_codec is None: idna_codec = IDNA_2003 if text == u'@': text = u'' if text: if text == u'.': 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 += unichr(total) elif c in [u'.', u'\u3002', u'\uff0e', u'\uff61']: if len(label) == 0: raise EmptyLabel labels.append(idna_codec.encode(label)) label = u'' elif c == u'\\': 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 from_text(text, origin=root, idna_codec=None): """Convert text into a Name object. @param text: The text to convert into a name. @type text: string @param origin: The origin to append to non-absolute names. @type origin: dns.name.Name @param idna_codec: IDNA encoder/decoder. If None, the default IDNA 2003 encoder/decoder is used. @type idna_codec: dns.name.IDNA @rtype: dns.name.Name object """ if isinstance(text, text_type): return from_unicode(text, origin, idna_codec) if not isinstance(text, binary_type): 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 bytearray(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) def from_wire(message, current): """Convert possibly compressed wire format into a Name. @param message: the entire DNS message @type message: string @param current: the offset of the beginning of the name from the start of the message @type current: int @raises dns.name.BadPointer: a compression pointer did not point backwards in the message @raises dns.name.BadLabelType: an invalid label type was encountered. @returns: a tuple consisting of the name that was read and the number of bytes of the wire format message which were consumed reading it @rtype: (dns.name.Name object, int) tuple """ if not isinstance(message, binary_type): raise ValueError("input to from_wire() must be a byte string") message = dns.wiredata.maybe_wrap(message) labels = [] biggest_pointer = current hops = 0 count = message[current] current += 1 cused = 1 while count != 0: if count < 64: labels.append(message[current: current + count].unwrap()) current += count if hops == 0: cused += count elif count >= 192: current = (count & 0x3f) * 256 + message[current] if hops == 0: cused += 1 if current >= biggest_pointer: raise BadPointer biggest_pointer = current hops += 1 else: raise BadLabelType count = message[current] current += 1 if hops == 0: cused += 1 labels.append('') return (Name(labels), cused)