s4-python: import a copy of the python dns library

This library is not installed on enough systems for us to rely
on it being available. We use the system copy if possible, and
fallback to this local copy

Pair-Programmed-With: Andrew Bartlett <abartlet@samba.org>

1 files changed, 1083 insertions, 0 deletions

diff --git a/source4/scripting/python/samba_external/dnspython/dns/message.py b/source4/scripting/python/samba_external/dnspython/dns/message.py
new file mode 100644
index 0000000000..ba0ebf65f1
--- /dev/null
+++ b/source4/scripting/python/samba_external/dnspython/dns/message.py
@@ -0,0 +1,1083 @@
+# 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