+++ /dev/null
-# Copyright (C) 2001-2007, 2009, 2010 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 Messages"""
-
-import cStringIO
-import random
-import struct
-import sys
-import time
-
-import dns.exception
-import dns.flags
-import dns.name
-import dns.opcode
-import dns.entropy
-import dns.rcode
-import dns.rdata
-import dns.rdataclass
-import dns.rdatatype
-import dns.rrset
-import dns.renderer
-import dns.tsig
-
-class ShortHeader(dns.exception.FormError):
- """Raised if the DNS packet passed to from_wire() is too short."""
- pass
-
-class TrailingJunk(dns.exception.FormError):
- """Raised if the DNS packet passed to from_wire() has extra junk
- at the end of it."""
- pass
-
-class UnknownHeaderField(dns.exception.DNSException):
- """Raised if a header field name is not recognized when converting from
- text into a message."""
- pass
-
-class BadEDNS(dns.exception.FormError):
- """Raised if an OPT record occurs somewhere other than the start of
- the additional data section."""
- pass
-
-class BadTSIG(dns.exception.FormError):
- """Raised if a TSIG record occurs somewhere other than the end of
- the additional data section."""
- pass
-
-class UnknownTSIGKey(dns.exception.DNSException):
- """Raised if we got a TSIG but don't know the key."""
- pass
-
-class Message(object):
- """A DNS message.
-
- @ivar id: The query id; the default is a randomly chosen id.
- @type id: int
- @ivar flags: The DNS flags of the message. @see: RFC 1035 for an
- explanation of these flags.
- @type flags: int
- @ivar question: The question section.
- @type question: list of dns.rrset.RRset objects
- @ivar answer: The answer section.
- @type answer: list of dns.rrset.RRset objects
- @ivar authority: The authority section.
- @type authority: list of dns.rrset.RRset objects
- @ivar additional: The additional data section.
- @type additional: list of dns.rrset.RRset objects
- @ivar edns: The EDNS level to use. The default is -1, no Edns.
- @type edns: int
- @ivar ednsflags: The EDNS flags
- @type ednsflags: long
- @ivar payload: The EDNS payload size. The default is 0.
- @type payload: int
- @ivar options: The EDNS options
- @type options: list of dns.edns.Option objects
- @ivar request_payload: The associated request's EDNS payload size.
- @type request_payload: int
- @ivar keyring: The TSIG keyring to use. The default is None.
- @type keyring: dict
- @ivar keyname: The TSIG keyname to use. The default is None.
- @type keyname: dns.name.Name object
- @ivar keyalgorithm: The TSIG key algorithm to use. The default is
- dns.tsig.default_algorithm.
- @type keyalgorithm: string
- @ivar request_mac: The TSIG MAC of the request message associated with
- this message; used when validating TSIG signatures. @see: RFC 2845 for
- more information on TSIG fields.
- @type request_mac: string
- @ivar fudge: TSIG time fudge; default is 300 seconds.
- @type fudge: int
- @ivar original_id: TSIG original id; defaults to the message's id
- @type original_id: int
- @ivar tsig_error: TSIG error code; default is 0.
- @type tsig_error: int
- @ivar other_data: TSIG other data.
- @type other_data: string
- @ivar mac: The TSIG MAC for this message.
- @type mac: string
- @ivar xfr: Is the message being used to contain the results of a DNS
- zone transfer? The default is False.
- @type xfr: bool
- @ivar origin: The origin of the zone in messages which are used for
- zone transfers or for DNS dynamic updates. The default is None.
- @type origin: dns.name.Name object
- @ivar tsig_ctx: The TSIG signature context associated with this
- message. The default is None.
- @type tsig_ctx: hmac.HMAC object
- @ivar had_tsig: Did the message decoded from wire format have a TSIG
- signature?
- @type had_tsig: bool
- @ivar multi: Is this message part of a multi-message sequence? The
- default is false. This variable is used when validating TSIG signatures
- on messages which are part of a zone transfer.
- @type multi: bool
- @ivar first: Is this message standalone, or the first of a multi
- message sequence? This variable is used when validating TSIG signatures
- on messages which are part of a zone transfer.
- @type first: bool
- @ivar index: An index of rrsets in the message. The index key is
- (section, name, rdclass, rdtype, covers, deleting). Indexing can be
- disabled by setting the index to None.
- @type index: dict
- """
-
- def __init__(self, id=None):
- if id is None:
- self.id = dns.entropy.random_16()
- else:
- self.id = id
- self.flags = 0
- self.question = []
- self.answer = []
- self.authority = []
- self.additional = []
- self.edns = -1
- self.ednsflags = 0
- self.payload = 0
- self.options = []
- self.request_payload = 0
- self.keyring = None
- self.keyname = None
- self.keyalgorithm = dns.tsig.default_algorithm
- self.request_mac = ''
- self.other_data = ''
- self.tsig_error = 0
- self.fudge = 300
- self.original_id = self.id
- self.mac = ''
- self.xfr = False
- self.origin = None
- self.tsig_ctx = None
- self.had_tsig = False
- self.multi = False
- self.first = True
- self.index = {}
-
- def __repr__(self):
- return '<DNS message, ID ' + `self.id` + '>'
-
- def __str__(self):
- return self.to_text()
-
- def to_text(self, origin=None, relativize=True, **kw):
- """Convert the message to text.
-
- The I{origin}, I{relativize}, and any other keyword
- arguments are passed to the rrset to_wire() method.
-
- @rtype: string
- """
-
- s = cStringIO.StringIO()
- print >> s, 'id %d' % self.id
- print >> s, 'opcode %s' % \
- dns.opcode.to_text(dns.opcode.from_flags(self.flags))
- rc = dns.rcode.from_flags(self.flags, self.ednsflags)
- print >> s, 'rcode %s' % dns.rcode.to_text(rc)
- print >> s, 'flags %s' % dns.flags.to_text(self.flags)
- if self.edns >= 0:
- print >> s, 'edns %s' % self.edns
- if self.ednsflags != 0:
- print >> s, 'eflags %s' % \
- dns.flags.edns_to_text(self.ednsflags)
- print >> s, 'payload', self.payload
- is_update = dns.opcode.is_update(self.flags)
- if is_update:
- print >> s, ';ZONE'
- else:
- print >> s, ';QUESTION'
- for rrset in self.question:
- print >> s, rrset.to_text(origin, relativize, **kw)
- if is_update:
- print >> s, ';PREREQ'
- else:
- print >> s, ';ANSWER'
- for rrset in self.answer:
- print >> s, rrset.to_text(origin, relativize, **kw)
- if is_update:
- print >> s, ';UPDATE'
- else:
- print >> s, ';AUTHORITY'
- for rrset in self.authority:
- print >> s, rrset.to_text(origin, relativize, **kw)
- print >> s, ';ADDITIONAL'
- for rrset in self.additional:
- print >> s, rrset.to_text(origin, relativize, **kw)
- #
- # We strip off the final \n so the caller can print the result without
- # doing weird things to get around eccentricities in Python print
- # formatting
- #
- return s.getvalue()[:-1]
-
- def __eq__(self, other):
- """Two messages are equal if they have the same content in the
- header, question, answer, and authority sections.
- @rtype: bool"""
- if not isinstance(other, Message):
- return False
- if self.id != other.id:
- return False
- if self.flags != other.flags:
- return False
- for n in self.question:
- if n not in other.question:
- return False
- for n in other.question:
- if n not in self.question:
- return False
- for n in self.answer:
- if n not in other.answer:
- return False
- for n in other.answer:
- if n not in self.answer:
- return False
- for n in self.authority:
- if n not in other.authority:
- return False
- for n in other.authority:
- if n not in self.authority:
- return False
- return True
-
- def __ne__(self, other):
- """Are two messages not equal?
- @rtype: bool"""
- return not self.__eq__(other)
-
- def is_response(self, other):
- """Is other a response to self?
- @rtype: bool"""
- if other.flags & dns.flags.QR == 0 or \
- self.id != other.id or \
- dns.opcode.from_flags(self.flags) != \
- dns.opcode.from_flags(other.flags):
- return False
- if dns.rcode.from_flags(other.flags, other.ednsflags) != \
- dns.rcode.NOERROR:
- return True
- if dns.opcode.is_update(self.flags):
- return True
- for n in self.question:
- if n not in other.question:
- return False
- for n in other.question:
- if n not in self.question:
- return False
- return True
-
- def section_number(self, section):
- if section is self.question:
- return 0
- elif section is self.answer:
- return 1
- elif section is self.authority:
- return 2
- elif section is self.additional:
- return 3
- else:
- raise ValueError('unknown section')
-
- def find_rrset(self, section, name, rdclass, rdtype,
- covers=dns.rdatatype.NONE, deleting=None, create=False,
- force_unique=False):
- """Find the RRset with the given attributes in the specified section.
-
- @param section: the section of the message to look in, e.g.
- self.answer.
- @type section: list of dns.rrset.RRset objects
- @param name: the name of the RRset
- @type name: dns.name.Name object
- @param rdclass: the class of the RRset
- @type rdclass: int
- @param rdtype: the type of the RRset
- @type rdtype: int
- @param covers: the covers value of the RRset
- @type covers: int
- @param deleting: the deleting value of the RRset
- @type deleting: int
- @param create: If True, create the RRset if it is not found.
- The created RRset is appended to I{section}.
- @type create: bool
- @param force_unique: If True and create is also True, create a
- new RRset regardless of whether a matching RRset exists already.
- @type force_unique: bool
- @raises KeyError: the RRset was not found and create was False
- @rtype: dns.rrset.RRset object"""
-
- key = (self.section_number(section),
- name, rdclass, rdtype, covers, deleting)
- if not force_unique:
- if not self.index is None:
- rrset = self.index.get(key)
- if not rrset is None:
- return rrset
- else:
- for rrset in section:
- if rrset.match(name, rdclass, rdtype, covers, deleting):
- return rrset
- if not create:
- raise KeyError
- rrset = dns.rrset.RRset(name, rdclass, rdtype, covers, deleting)
- section.append(rrset)
- if not self.index is None:
- self.index[key] = rrset
- return rrset
-
- def get_rrset(self, section, name, rdclass, rdtype,
- covers=dns.rdatatype.NONE, deleting=None, create=False,
- force_unique=False):
- """Get the RRset with the given attributes in the specified section.
-
- If the RRset is not found, None is returned.
-
- @param section: the section of the message to look in, e.g.
- self.answer.
- @type section: list of dns.rrset.RRset objects
- @param name: the name of the RRset
- @type name: dns.name.Name object
- @param rdclass: the class of the RRset
- @type rdclass: int
- @param rdtype: the type of the RRset
- @type rdtype: int
- @param covers: the covers value of the RRset
- @type covers: int
- @param deleting: the deleting value of the RRset
- @type deleting: int
- @param create: If True, create the RRset if it is not found.
- The created RRset is appended to I{section}.
- @type create: bool
- @param force_unique: If True and create is also True, create a
- new RRset regardless of whether a matching RRset exists already.
- @type force_unique: bool
- @rtype: dns.rrset.RRset object or None"""
-
- try:
- rrset = self.find_rrset(section, name, rdclass, rdtype, covers,
- deleting, create, force_unique)
- except KeyError:
- rrset = None
- return rrset
-
- def to_wire(self, origin=None, max_size=0, **kw):
- """Return a string containing the message in DNS compressed wire
- format.
-
- Additional keyword arguments are passed to the rrset to_wire()
- method.
-
- @param origin: The origin to be appended to any relative names.
- @type origin: dns.name.Name object
- @param max_size: The maximum size of the wire format output; default
- is 0, which means 'the message's request payload, if nonzero, or
- 65536'.
- @type max_size: int
- @raises dns.exception.TooBig: max_size was exceeded
- @rtype: string
- """
-
- if max_size == 0:
- if self.request_payload != 0:
- max_size = self.request_payload
- else:
- max_size = 65535
- if max_size < 512:
- max_size = 512
- elif max_size > 65535:
- max_size = 65535
- r = dns.renderer.Renderer(self.id, self.flags, max_size, origin)
- for rrset in self.question:
- r.add_question(rrset.name, rrset.rdtype, rrset.rdclass)
- for rrset in self.answer:
- r.add_rrset(dns.renderer.ANSWER, rrset, **kw)
- for rrset in self.authority:
- r.add_rrset(dns.renderer.AUTHORITY, rrset, **kw)
- if self.edns >= 0:
- r.add_edns(self.edns, self.ednsflags, self.payload, self.options)
- for rrset in self.additional:
- r.add_rrset(dns.renderer.ADDITIONAL, rrset, **kw)
- r.write_header()
- if not self.keyname is None:
- r.add_tsig(self.keyname, self.keyring[self.keyname],
- self.fudge, self.original_id, self.tsig_error,
- self.other_data, self.request_mac,
- self.keyalgorithm)
- self.mac = r.mac
- return r.get_wire()
-
- def use_tsig(self, keyring, keyname=None, fudge=300,
- original_id=None, tsig_error=0, other_data='',
- algorithm=dns.tsig.default_algorithm):
- """When sending, a TSIG signature using the specified keyring
- and keyname should be added.
-
- @param keyring: The TSIG keyring to use; defaults to None.
- @type keyring: dict
- @param keyname: The name of the TSIG key to use; defaults to None.
- The key must be defined in the keyring. If a keyring is specified
- but a keyname is not, then the key used will be the first key in the
- keyring. Note that the order of keys in a dictionary is not defined,
- so applications should supply a keyname when a keyring is used, unless
- they know the keyring contains only one key.
- @type keyname: dns.name.Name or string
- @param fudge: TSIG time fudge; default is 300 seconds.
- @type fudge: int
- @param original_id: TSIG original id; defaults to the message's id
- @type original_id: int
- @param tsig_error: TSIG error code; default is 0.
- @type tsig_error: int
- @param other_data: TSIG other data.
- @type other_data: string
- @param algorithm: The TSIG algorithm to use; defaults to
- dns.tsig.default_algorithm
- """
-
- self.keyring = keyring
- if keyname is None:
- self.keyname = self.keyring.keys()[0]
- else:
- if isinstance(keyname, (str, unicode)):
- keyname = dns.name.from_text(keyname)
- self.keyname = keyname
- self.keyalgorithm = algorithm
- self.fudge = fudge
- if original_id is None:
- self.original_id = self.id
- else:
- self.original_id = original_id
- self.tsig_error = tsig_error
- self.other_data = other_data
-
- def use_edns(self, edns=0, ednsflags=0, payload=1280, request_payload=None, options=None):
- """Configure EDNS behavior.
- @param edns: The EDNS level to use. Specifying None, False, or -1
- means 'do not use EDNS', and in this case the other parameters are
- ignored. Specifying True is equivalent to specifying 0, i.e. 'use
- EDNS0'.
- @type edns: int or bool or None
- @param ednsflags: EDNS flag values.
- @type ednsflags: int
- @param payload: The EDNS sender's payload field, which is the maximum
- size of UDP datagram the sender can handle.
- @type payload: int
- @param request_payload: The EDNS payload size to use when sending
- this message. If not specified, defaults to the value of payload.
- @type request_payload: int or None
- @param options: The EDNS options
- @type options: None or list of dns.edns.Option objects
- @see: RFC 2671
- """
- if edns is None or edns is False:
- edns = -1
- if edns is True:
- edns = 0
- if request_payload is None:
- request_payload = payload
- if edns < 0:
- ednsflags = 0
- payload = 0
- request_payload = 0
- options = []
- else:
- # make sure the EDNS version in ednsflags agrees with edns
- ednsflags &= 0xFF00FFFFL
- ednsflags |= (edns << 16)
- if options is None:
- options = []
- self.edns = edns
- self.ednsflags = ednsflags
- self.payload = payload
- self.options = options
- self.request_payload = request_payload
-
- def want_dnssec(self, wanted=True):
- """Enable or disable 'DNSSEC desired' flag in requests.
- @param wanted: Is DNSSEC desired? If True, EDNS is enabled if
- required, and then the DO bit is set. If False, the DO bit is
- cleared if EDNS is enabled.
- @type wanted: bool
- """
- if wanted:
- if self.edns < 0:
- self.use_edns()
- self.ednsflags |= dns.flags.DO
- elif self.edns >= 0:
- self.ednsflags &= ~dns.flags.DO
-
- def rcode(self):
- """Return the rcode.
- @rtype: int
- """
- return dns.rcode.from_flags(self.flags, self.ednsflags)
-
- def set_rcode(self, rcode):
- """Set the rcode.
- @param rcode: the rcode
- @type rcode: int
- """
- (value, evalue) = dns.rcode.to_flags(rcode)
- self.flags &= 0xFFF0
- self.flags |= value
- self.ednsflags &= 0x00FFFFFFL
- self.ednsflags |= evalue
- if self.ednsflags != 0 and self.edns < 0:
- self.edns = 0
-
- def opcode(self):
- """Return the opcode.
- @rtype: int
- """
- return dns.opcode.from_flags(self.flags)
-
- def set_opcode(self, opcode):
- """Set the opcode.
- @param opcode: the opcode
- @type opcode: int
- """
- self.flags &= 0x87FF
- self.flags |= dns.opcode.to_flags(opcode)
-
-class _WireReader(object):
- """Wire format reader.
-
- @ivar wire: the wire-format message.
- @type wire: string
- @ivar message: The message object being built
- @type message: dns.message.Message object
- @ivar current: When building a message object from wire format, this
- variable contains the offset from the beginning of wire of the next octet
- to be read.
- @type current: int
- @ivar updating: Is the message a dynamic update?
- @type updating: bool
- @ivar one_rr_per_rrset: Put each RR into its own RRset?
- @type one_rr_per_rrset: bool
- @ivar zone_rdclass: The class of the zone in messages which are
- DNS dynamic updates.
- @type zone_rdclass: int
- """
-
- def __init__(self, wire, message, question_only=False,
- one_rr_per_rrset=False):
- self.wire = wire
- self.message = message
- self.current = 0
- self.updating = False
- self.zone_rdclass = dns.rdataclass.IN
- self.question_only = question_only
- self.one_rr_per_rrset = one_rr_per_rrset
-
- def _get_question(self, qcount):
- """Read the next I{qcount} records from the wire data and add them to
- the question section.
- @param qcount: the number of questions in the message
- @type qcount: int"""
-
- if self.updating and qcount > 1:
- raise dns.exception.FormError
-
- for i in xrange(0, qcount):
- (qname, used) = dns.name.from_wire(self.wire, self.current)
- if not self.message.origin is None:
- qname = qname.relativize(self.message.origin)
- self.current = self.current + used
- (rdtype, rdclass) = \
- struct.unpack('!HH',
- self.wire[self.current:self.current + 4])
- self.current = self.current + 4
- self.message.find_rrset(self.message.question, qname,
- rdclass, rdtype, create=True,
- force_unique=True)
- if self.updating:
- self.zone_rdclass = rdclass
-
- def _get_section(self, section, count):
- """Read the next I{count} records from the wire data and add them to
- the specified section.
- @param section: the section of the message to which to add records
- @type section: list of dns.rrset.RRset objects
- @param count: the number of records to read
- @type count: int"""
-
- if self.updating or self.one_rr_per_rrset:
- force_unique = True
- else:
- force_unique = False
- seen_opt = False
- for i in xrange(0, count):
- rr_start = self.current
- (name, used) = dns.name.from_wire(self.wire, self.current)
- absolute_name = name
- if not self.message.origin is None:
- name = name.relativize(self.message.origin)
- self.current = self.current + used
- (rdtype, rdclass, ttl, rdlen) = \
- struct.unpack('!HHIH',
- self.wire[self.current:self.current + 10])
- self.current = self.current + 10
- if rdtype == dns.rdatatype.OPT:
- if not section is self.message.additional or seen_opt:
- raise BadEDNS
- self.message.payload = rdclass
- self.message.ednsflags = ttl
- self.message.edns = (ttl & 0xff0000) >> 16
- self.message.options = []
- current = self.current
- optslen = rdlen
- while optslen > 0:
- (otype, olen) = \
- struct.unpack('!HH',
- self.wire[current:current + 4])
- current = current + 4
- opt = dns.edns.option_from_wire(otype, self.wire, current, olen)
- self.message.options.append(opt)
- current = current + olen
- optslen = optslen - 4 - olen
- seen_opt = True
- elif rdtype == dns.rdatatype.TSIG:
- if not (section is self.message.additional and
- i == (count - 1)):
- raise BadTSIG
- if self.message.keyring is None:
- raise UnknownTSIGKey('got signed message without keyring')
- secret = self.message.keyring.get(absolute_name)
- if secret is None:
- raise UnknownTSIGKey("key '%s' unknown" % name)
- self.message.tsig_ctx = \
- dns.tsig.validate(self.wire,
- absolute_name,
- secret,
- int(time.time()),
- self.message.request_mac,
- rr_start,
- self.current,
- rdlen,
- self.message.tsig_ctx,
- self.message.multi,
- self.message.first)
- self.message.had_tsig = True
- else:
- if ttl < 0:
- ttl = 0
- if self.updating and \
- (rdclass == dns.rdataclass.ANY or
- rdclass == dns.rdataclass.NONE):
- deleting = rdclass
- rdclass = self.zone_rdclass
- else:
- deleting = None
- if deleting == dns.rdataclass.ANY or \
- (deleting == dns.rdataclass.NONE and \
- section == self.message.answer):
- covers = dns.rdatatype.NONE
- rd = None
- else:
- rd = dns.rdata.from_wire(rdclass, rdtype, self.wire,
- self.current, rdlen,
- self.message.origin)
- covers = rd.covers()
- if self.message.xfr and rdtype == dns.rdatatype.SOA:
- force_unique = True
- rrset = self.message.find_rrset(section, name,
- rdclass, rdtype, covers,
- deleting, True, force_unique)
- if not rd is None:
- rrset.add(rd, ttl)
- self.current = self.current + rdlen
-
- def read(self):
- """Read a wire format DNS message and build a dns.message.Message
- object."""
-
- l = len(self.wire)
- if l < 12:
- raise ShortHeader
- (self.message.id, self.message.flags, qcount, ancount,
- aucount, adcount) = struct.unpack('!HHHHHH', self.wire[:12])
- self.current = 12
- if dns.opcode.is_update(self.message.flags):
- self.updating = True
- self._get_question(qcount)
- if self.question_only:
- return
- self._get_section(self.message.answer, ancount)
- self._get_section(self.message.authority, aucount)
- self._get_section(self.message.additional, adcount)
- if self.current != l:
- raise TrailingJunk
- if self.message.multi and self.message.tsig_ctx and \
- not self.message.had_tsig:
- self.message.tsig_ctx.update(self.wire)
-
-
-def from_wire(wire, keyring=None, request_mac='', xfr=False, origin=None,
- tsig_ctx = None, multi = False, first = True,
- question_only = False, one_rr_per_rrset = False):
- """Convert a DNS wire format message into a message
- object.
-
- @param keyring: The keyring to use if the message is signed.
- @type keyring: dict
- @param request_mac: If the message is a response to a TSIG-signed request,
- I{request_mac} should be set to the MAC of that request.
- @type request_mac: string
- @param xfr: Is this message part of a zone transfer?
- @type xfr: bool
- @param origin: If the message is part of a zone transfer, I{origin}
- should be the origin name of the zone.
- @type origin: dns.name.Name object
- @param tsig_ctx: The ongoing TSIG context, used when validating zone
- transfers.
- @type tsig_ctx: hmac.HMAC object
- @param multi: Is this message part of a multiple message sequence?
- @type multi: bool
- @param first: Is this message standalone, or the first of a multi
- message sequence?
- @type first: bool
- @param question_only: Read only up to the end of the question section?
- @type question_only: bool
- @param one_rr_per_rrset: Put each RR into its own RRset
- @type one_rr_per_rrset: bool
- @raises ShortHeader: The message is less than 12 octets long.
- @raises TrailingJunk: There were octets in the message past the end
- of the proper DNS message.
- @raises BadEDNS: An OPT record was in the wrong section, or occurred more
- than once.
- @raises BadTSIG: A TSIG record was not the last record of the additional
- data section.
- @rtype: dns.message.Message object"""
-
- m = Message(id=0)
- m.keyring = keyring
- m.request_mac = request_mac
- m.xfr = xfr
- m.origin = origin
- m.tsig_ctx = tsig_ctx
- m.multi = multi
- m.first = first
-
- reader = _WireReader(wire, m, question_only, one_rr_per_rrset)
- reader.read()
-
- return m
-
-
-class _TextReader(object):
- """Text format reader.
-
- @ivar tok: the tokenizer
- @type tok: dns.tokenizer.Tokenizer object
- @ivar message: The message object being built
- @type message: dns.message.Message object
- @ivar updating: Is the message a dynamic update?
- @type updating: bool
- @ivar zone_rdclass: The class of the zone in messages which are
- DNS dynamic updates.
- @type zone_rdclass: int
- @ivar last_name: The most recently read name when building a message object
- from text format.
- @type last_name: dns.name.Name object
- """
-
- def __init__(self, text, message):
- self.message = message
- self.tok = dns.tokenizer.Tokenizer(text)
- self.last_name = None
- self.zone_rdclass = dns.rdataclass.IN
- self.updating = False
-
- def _header_line(self, section):
- """Process one line from the text format header section."""
-
- token = self.tok.get()
- what = token.value
- if what == 'id':
- self.message.id = self.tok.get_int()
- elif what == 'flags':
- while True:
- token = self.tok.get()
- if not token.is_identifier():
- self.tok.unget(token)
- break
- self.message.flags = self.message.flags | \
- dns.flags.from_text(token.value)
- if dns.opcode.is_update(self.message.flags):
- self.updating = True
- elif what == 'edns':
- self.message.edns = self.tok.get_int()
- self.message.ednsflags = self.message.ednsflags | \
- (self.message.edns << 16)
- elif what == 'eflags':
- if self.message.edns < 0:
- self.message.edns = 0
- while True:
- token = self.tok.get()
- if not token.is_identifier():
- self.tok.unget(token)
- break
- self.message.ednsflags = self.message.ednsflags | \
- dns.flags.edns_from_text(token.value)
- elif what == 'payload':
- self.message.payload = self.tok.get_int()
- if self.message.edns < 0:
- self.message.edns = 0
- elif what == 'opcode':
- text = self.tok.get_string()
- self.message.flags = self.message.flags | \
- dns.opcode.to_flags(dns.opcode.from_text(text))
- elif what == 'rcode':
- text = self.tok.get_string()
- self.message.set_rcode(dns.rcode.from_text(text))
- else:
- raise UnknownHeaderField
- self.tok.get_eol()
-
- def _question_line(self, section):
- """Process one line from the text format question section."""
-
- token = self.tok.get(want_leading = True)
- if not token.is_whitespace():
- self.last_name = dns.name.from_text(token.value, None)
- name = self.last_name
- token = self.tok.get()
- if not token.is_identifier():
- raise dns.exception.SyntaxError
- # Class
- try:
- rdclass = dns.rdataclass.from_text(token.value)
- token = self.tok.get()
- if not token.is_identifier():
- raise dns.exception.SyntaxError
- except dns.exception.SyntaxError:
- raise dns.exception.SyntaxError
- except:
- rdclass = dns.rdataclass.IN
- # Type
- rdtype = dns.rdatatype.from_text(token.value)
- self.message.find_rrset(self.message.question, name,
- rdclass, rdtype, create=True,
- force_unique=True)
- if self.updating:
- self.zone_rdclass = rdclass
- self.tok.get_eol()
-
- def _rr_line(self, section):
- """Process one line from the text format answer, authority, or
- additional data sections.
- """
-
- deleting = None
- # Name
- token = self.tok.get(want_leading = True)
- if not token.is_whitespace():
- self.last_name = dns.name.from_text(token.value, None)
- name = self.last_name
- token = self.tok.get()
- if not token.is_identifier():
- raise dns.exception.SyntaxError
- # TTL
- try:
- ttl = int(token.value, 0)
- token = self.tok.get()
- if not token.is_identifier():
- raise dns.exception.SyntaxError
- except dns.exception.SyntaxError:
- raise dns.exception.SyntaxError
- except:
- ttl = 0
- # Class
- try:
- rdclass = dns.rdataclass.from_text(token.value)
- token = self.tok.get()
- if not token.is_identifier():
- raise dns.exception.SyntaxError
- if rdclass == dns.rdataclass.ANY or rdclass == dns.rdataclass.NONE:
- deleting = rdclass
- rdclass = self.zone_rdclass
- except dns.exception.SyntaxError:
- raise dns.exception.SyntaxError
- except:
- rdclass = dns.rdataclass.IN
- # Type
- rdtype = dns.rdatatype.from_text(token.value)
- token = self.tok.get()
- if not token.is_eol_or_eof():
- self.tok.unget(token)
- rd = dns.rdata.from_text(rdclass, rdtype, self.tok, None)
- covers = rd.covers()
- else:
- rd = None
- covers = dns.rdatatype.NONE
- rrset = self.message.find_rrset(section, name,
- rdclass, rdtype, covers,
- deleting, True, self.updating)
- if not rd is None:
- rrset.add(rd, ttl)
-
- def read(self):
- """Read a text format DNS message and build a dns.message.Message
- object."""
-
- line_method = self._header_line
- section = None
- while 1:
- token = self.tok.get(True, True)
- if token.is_eol_or_eof():
- break
- if token.is_comment():
- u = token.value.upper()
- if u == 'HEADER':
- line_method = self._header_line
- elif u == 'QUESTION' or u == 'ZONE':
- line_method = self._question_line
- section = self.message.question
- elif u == 'ANSWER' or u == 'PREREQ':
- line_method = self._rr_line
- section = self.message.answer
- elif u == 'AUTHORITY' or u == 'UPDATE':
- line_method = self._rr_line
- section = self.message.authority
- elif u == 'ADDITIONAL':
- line_method = self._rr_line
- section = self.message.additional
- self.tok.get_eol()
- continue
- self.tok.unget(token)
- line_method(section)
-
-
-def from_text(text):
- """Convert the text format message into a message object.
-
- @param text: The text format message.
- @type text: string
- @raises UnknownHeaderField:
- @raises dns.exception.SyntaxError:
- @rtype: dns.message.Message object"""
-
- # 'text' can also be a file, but we don't publish that fact
- # since it's an implementation detail. The official file
- # interface is from_file().
-
- m = Message()
-
- reader = _TextReader(text, m)
- reader.read()
-
- return m
-
-def from_file(f):
- """Read the next text format message from the specified file.
-
- @param f: file or string. If I{f} is a string, it is treated
- as the name of a file to open.
- @raises UnknownHeaderField:
- @raises dns.exception.SyntaxError:
- @rtype: dns.message.Message object"""
-
- if sys.hexversion >= 0x02030000:
- # allow Unicode filenames; turn on universal newline support
- str_type = basestring
- opts = 'rU'
- else:
- str_type = str
- opts = 'r'
- if isinstance(f, str_type):
- f = file(f, opts)
- want_close = True
- else:
- want_close = False
-
- try:
- m = from_text(f)
- finally:
- if want_close:
- f.close()
- return m
-
-def make_query(qname, rdtype, rdclass = dns.rdataclass.IN, use_edns=None,
- want_dnssec=False):
- """Make a query message.
-
- The query name, type, and class may all be specified either
- as objects of the appropriate type, or as strings.
-
- The query will have a randomly choosen query id, and its DNS flags
- will be set to dns.flags.RD.
-
- @param qname: The query name.
- @type qname: dns.name.Name object or string
- @param rdtype: The desired rdata type.
- @type rdtype: int
- @param rdclass: The desired rdata class; the default is class IN.
- @type rdclass: int
- @param use_edns: The EDNS level to use; the default is None (no EDNS).
- See the description of dns.message.Message.use_edns() for the possible
- values for use_edns and their meanings.
- @type use_edns: int or bool or None
- @param want_dnssec: Should the query indicate that DNSSEC is desired?
- @type want_dnssec: bool
- @rtype: dns.message.Message object"""
-
- if isinstance(qname, (str, unicode)):
- qname = dns.name.from_text(qname)
- if isinstance(rdtype, str):
- rdtype = dns.rdatatype.from_text(rdtype)
- if isinstance(rdclass, str):
- rdclass = dns.rdataclass.from_text(rdclass)
- m = Message()
- m.flags |= dns.flags.RD
- m.find_rrset(m.question, qname, rdclass, rdtype, create=True,
- force_unique=True)
- m.use_edns(use_edns)
- m.want_dnssec(want_dnssec)
- return m
-
-def make_response(query, recursion_available=False, our_payload=8192):
- """Make a message which is a response for the specified query.
- The message returned is really a response skeleton; it has all
- of the infrastructure required of a response, but none of the
- content.
-
- The response's question section is a shallow copy of the query's
- question section, so the query's question RRsets should not be
- changed.
-
- @param query: the query to respond to
- @type query: dns.message.Message object
- @param recursion_available: should RA be set in the response?
- @type recursion_available: bool
- @param our_payload: payload size to advertise in EDNS responses; default
- is 8192.
- @type our_payload: int
- @rtype: dns.message.Message object"""
-
- if query.flags & dns.flags.QR:
- raise dns.exception.FormError('specified query message is not a query')
- response = dns.message.Message(query.id)
- response.flags = dns.flags.QR | (query.flags & dns.flags.RD)
- if recursion_available:
- response.flags |= dns.flags.RA
- response.set_opcode(query.opcode())
- response.question = list(query.question)
- if query.edns >= 0:
- response.use_edns(0, 0, our_payload, query.payload)
- if not query.keyname is None:
- response.keyname = query.keyname
- response.keyring = query.keyring
- response.request_mac = query.mac
- return response
git.samba.org / idra / samba.git / blobdiff