# Copyright (C) 2003-2007 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 Zones."""
from __future__ import generators
import sys
import dns.exception
import dns.name
import dns.node
import dns.rdataclass
import dns.rdatatype
import dns.rdata
import dns.rrset
import dns.tokenizer
import dns.ttl
class BadZone(dns.exception.DNSException):
"""The zone is malformed."""
pass
class NoSOA(BadZone):
"""The zone has no SOA RR at its origin."""
pass
class NoNS(BadZone):
"""The zone has no NS RRset at its origin."""
pass
class UnknownOrigin(BadZone):
"""The zone's origin is unknown."""
pass
class Zone(object):
"""A DNS zone.
A Zone is a mapping from names to nodes. The zone object may be
treated like a Python dictionary, e.g. zone[name] will retrieve
the node associated with that name. The I{name} may be a
dns.name.Name object, or it may be a string. In the either case,
if the name is relative it is treated as relative to the origin of
the zone.
@ivar rdclass: The zone's rdata class; the default is class IN.
@type rdclass: int
@ivar origin: The origin of the zone.
@type origin: dns.name.Name object
@ivar nodes: A dictionary mapping the names of nodes in the zone to the
nodes themselves.
@type nodes: dict
@ivar relativize: should names in the zone be relativized?
@type relativize: bool
@cvar node_factory: the factory used to create a new node
@type node_factory: class or callable
"""
node_factory = dns.node.Node
__slots__ = ['rdclass', 'origin', 'nodes', 'relativize']
def __init__(self, origin, rdclass=dns.rdataclass.IN, relativize=True):
"""Initialize a zone object.
@param origin: The origin of the zone.
@type origin: dns.name.Name object
@param rdclass: The zone's rdata class; the default is class IN.
@type rdclass: int"""
self.rdclass = rdclass
self.origin = origin
self.nodes = {}
self.relativize = relativize
def __eq__(self, other):
"""Two zones are equal if they have the same origin, class, and
nodes.
@rtype: bool
"""
if not isinstance(other, Zone):
return False
if self.rdclass != other.rdclass or \
self.origin != other.origin or \
self.nodes != other.nodes:
return False
return True
def __ne__(self, other):
"""Are two zones not equal?
@rtype: bool
"""
return not self.__eq__(other)
def _validate_name(self, name):
if isinstance(name, (str, unicode)):
name = dns.name.from_text(name, None)
elif not isinstance(name, dns.name.Name):
raise KeyError, \
"name parameter must be convertable to a DNS name"
if name.is_absolute():
if not name.is_subdomain(self.origin):
raise KeyError, \
"name parameter must be a subdomain of the zone origin"
if self.relativize:
name = name.relativize(self.origin)
return name
def __getitem__(self, key):
key = self._validate_name(key)
return self.nodes[key]
def __setitem__(self, key, value):
key = self._validate_name(key)
self.nodes[key] = value
def __delitem__(self, key):
key = self._validate_name(key)
del self.nodes[key]
def __iter__(self):
return self.nodes.iterkeys()
def iterkeys(self):
return self.nodes.iterkeys()
def keys(self):
return self.nodes.keys()
def itervalues(self):
return self.nodes.itervalues()
def values(self):
return self.nodes.values()
def iteritems(self):
return self.nodes.iteritems()
def items(self):
return self.nodes.items()
def get(self, key):
key = self._validate_name(key)
return self.nodes.get(key)
def __contains__(self, other):
return other in self.nodes
def find_node(self, name, create=False):
"""Find a node in the zone, possibly creating it.
@param name: the name of the node to find
@type name: dns.name.Name object or string
@param create: should the node be created if it doesn't exist?
@type create: bool
@raises KeyError: the name is not known and create was not specified.
@rtype: dns.node.Node object
"""
name = self._validate_name(name)
node = self.nodes.get(name)
if node is None:
if not create:
raise KeyError
node = self.node_factory()
self.nodes[name] = node
return node
def get_node(self, name, create=False):
"""Get a node in the zone, possibly creating it.
This method is like L{find_node}, except it returns None instead
of raising an exception if the node does not exist and creation
has not been requested.
@param name: the name of the node to find
@type name: dns.name.Name object or string
@param create: should the node be created if it doesn't exist?
@type create: bool
@rtype: dns.node.Node object or None
"""
try:
node = self.find_node(name, create)
except KeyError:
node = None
return node
def delete_node(self, name):
"""Delete the specified node if it exists.
It is not an error if the node does not exist.
"""
name = self._validate_name(name)
if self.nodes.has_key(name):
del self.nodes[name]
def find_rdataset(self, name, rdtype, covers=dns.rdatatype.NONE,
create=False):
"""Look for rdata with the specified name and type in the zone,
and return an rdataset encapsulating it.
The I{name}, I{rdtype}, and I{covers} parameters may be
strings, in which case they will be converted to their proper
type.
The rdataset returned is not a copy; changes to it will change
the zone.
KeyError is raised if the name or type are not found.
Use L{get_rdataset} if you want to have None returned instead.
@param name: the owner name to look for
@type name: DNS.name.Name object or string
@param rdtype: the rdata type desired
@type rdtype: int or string
@param covers: the covered type (defaults to None)
@type covers: int or string
@param create: should the node and rdataset be created if they do not
exist?
@type create: bool
@raises KeyError: the node or rdata could not be found
@rtype: dns.rrset.RRset object
"""
name = self._validate_name(name)
if isinstance(rdtype, str):
rdtype = dns.rdatatype.from_text(rdtype)
if isinstance(covers, str):
covers = dns.rdatatype.from_text(covers)
node = self.find_node(name, create)
return node.find_rdataset(self.rdclass, rdtype, covers, create)
def get_rdataset(self, name, rdtype, covers=dns.rdatatype.NONE,
create=False):
"""Look for rdata with the specified name and type in the zone,
and return an rdataset encapsulating it.
The I{name}, I{rdtype}, and I{covers} parameters may be
strings, in which case they will be converted to their proper
type.
The rdataset returned is not a copy; changes to it will change
the zone.
None is returned if the name or type are not found.
Use L{find_rdataset} if you want to have KeyError raised instead.
@param name: the owner name to look for
@type name: DNS.name.Name object or string
@param rdtype: the rdata type desired
@type rdtype: int or string
@param covers: the covered type (defaults to None)
@type covers: int or string
@param create: should the node and rdataset be created if they do not
exist?
@type create: bool
@rtype: dns.rrset.RRset object
"""
try:
rdataset = self.find_rdataset(name, rdtype, covers, create)
except KeyError:
rdataset = None
return rdataset
def delete_rdataset(self, name, rdtype, covers=dns.rdatatype.NONE):
"""Delete the rdataset matching I{rdtype} and I{covers}, if it
exists at the node specified by I{name}.
The I{name}, I{rdtype}, and I{covers} parameters may be
strings, in which case they will be converted to their proper
type.
It is not an error if the node does not exist, or if there is no
matching rdataset at the node.
If the node has no rdatasets after the deletion, it will itself
be deleted.
@param name: the owner name to look for
@type name: DNS.name.Name object or string
@param rdtype: the rdata type desired
@type rdtype: int or string
@param covers: the covered type (defaults to None)
@type covers: int or string
"""
name = self._validate_name(name)
if isinstance(rdtype, str):
rdtype = dns.rdatatype.from_text(rdtype)
if isinstance(covers, str):
covers = dns.rdatatype.from_text(covers)
node = self.get_node(name)
if not node is None:
node.delete_rdataset(self.rdclass, rdtype, covers)
if len(node) == 0:
self.delete_node(name)
def replace_rdataset(self, name, replacement):
"""Replace an rdataset at name.
It is not an error if there is no rdataset matching I{replacement}.
Ownership of the I{replacement} object is transferred to the zone;
in other words, this method does not store a copy of I{replacement}
at the node, it stores I{replacement} itself.
If the I{name} node does not exist, it is created.
@param name: the owner name
@type name: DNS.name.Name object or string
@param replacement: the replacement rdataset
@type replacement: dns.rdataset.Rdataset
"""
if replacement.rdclass != self.rdclass:
raise ValueError, 'replacement.rdclass != zone.rdclass'
node = self.find_node(name, True)
node.replace_rdataset(replacement)
def find_rrset(self, name, rdtype, covers=dns.rdatatype.NONE):
"""Look for rdata with the specified name and type in the zone,
and return an RRset encapsulating it.
The I{name}, I{rdtype}, and I{covers} parameters may be
strings, in which case they will be converted to their proper
type.
This method is less efficient than the similar
L{find_rdataset} because it creates an RRset instead of
returning the matching rdataset. It may be more convenient
for some uses since it returns an object which binds the owner
name to the rdata.
This method may not be used to create new nodes or rdatasets;
use L{find_rdataset} instead.
KeyError is raised if the name or type are not found.
Use L{get_rrset} if you want to have None returned instead.
@param name: the owner name to look for
@type name: DNS.name.Name object or string
@param rdtype: the rdata type desired
@type rdtype: int or string
@param covers: the covered type (defaults to None)
@type covers: int or string
@raises KeyError: the node or rdata could not be found
@rtype: dns.rrset.RRset object
"""
name = self._validate_name(name)
if isinstance(rdtype, str):
rdtype = dns.rdatatype.from_text(rdtype)
if isinstance(covers, str):
covers = dns.rdatatype.from_text(covers)
rdataset = self.nodes[name].find_rdataset(self.rdclass, rdtype, covers)
rrset = dns.rrset.RRset(name, self.rdclass, rdtype, covers)
rrset.update(rdataset)
return rrset
def get_rrset(self, name, rdtype, covers=dns.rdatatype.NONE):
"""Look for rdata with the specified name and type in the zone,
and return an RRset encapsulating it.
The I{name}, I{rdtype}, and I{covers} parameters may be
strings, in which case they will be converted to their proper
type.
This method is less efficient than the similar L{get_rdataset}
because it creates an RRset instead of returning the matching
rdataset. It may be more convenient for some uses since it
returns an object which binds the owner name to the rdata.
This method may not be used to create new nodes or rdatasets;
use L{find_rdataset} instead.
None is returned if the name or type are not found.
Use L{find_rrset} if you want to have KeyError raised instead.
@param name: the owner name to look for
@type name: DNS.name.Name object or string
@param rdtype: the rdata type desired
@type rdtype: int or string
@param covers: the covered type (defaults to None)
@type covers: int or string
@rtype: dns.rrset.RRset object
"""
try:
rrset = self.find_rrset(name, rdtype, covers)
except KeyError:
rrset = None
return rrset
def iterate_rdatasets(self, rdtype=dns.rdatatype.ANY,
covers=dns.rdatatype.NONE):
"""Return a generator which yields (name, rdataset) tuples for
all rdatasets in the zone which have the specified I{rdtype}
and I{covers}. If I{rdtype} is dns.rdatatype.ANY, the default,
then all rdatasets will be matched.
@param rdtype: int or string
@type rdtype: int or string
@param covers: the covered type (defaults to None)
@type covers: int or string
"""
if isinstance(rdtype, str):
rdtype = dns.rdatatype.from_text(rdtype)
if isinstance(covers, str):
covers = dns.rdatatype.from_text(covers)
for (name, node) in self.iteritems():
for rds in node:
if rdtype == dns.rdatatype.ANY or \
(rds.rdtype == rdtype and rds.covers == covers):
yield (name, rds)
def iterate_rdatas(self, rdtype=dns.rdatatype.ANY,
covers=dns.rdatatype.NONE):
"""Return a generator which yields (name, ttl, rdata) tuples for
all rdatas in the zone which have the specified I{rdtype}
and I{covers}. If I{rdtype} is dns.rdatatype.ANY, the default,
then all rdatas will be matched.
@param rdtype: int or string
@type rdtype: int or string
@param covers: the covered type (defaults to None)
@type covers: int or string
"""
if isinstance(rdtype, str):
rdtype = dns.rdatatype.from_text(rdtype)
if isinstance(covers, str):
covers = dns.rdatatype.from_text(covers)
for (name, node) in self.iteritems():
for rds in node:
if rdtype == dns.rdatatype.ANY or \
(rds.rdtype == rdtype and rds.covers == covers):
for rdata in rds:
yield (name, rds.ttl, rdata)
def to_file(self, f, sorted=True, relativize=True, nl=None):
"""Write a zone to a file.
@param f: file or string. If I{f} is a string, it is treated
as the name of a file to open.
@param sorted: if True, the file will be written with the
names sorted in DNSSEC order from least to greatest. Otherwise
the names will be written in whatever order they happen to have
in the zone's dictionary.
@param relativize: if True, domain names in the output will be
relativized to the zone's origin (if possible).
@type relativize: bool
@param nl: The end of line string. If not specified, the
output will use the platform's native end-of-line marker (i.e.
LF on POSIX, CRLF on Windows, CR on Macintosh).
@type nl: string or None
"""
if sys.hexversion >= 0x02030000:
# allow Unicode filenames
str_type = basestring
else:
str_type = str
if nl is None:
opts = 'w'
else:
opts = 'wb'
if isinstance(f, str_type):
f = file(f, opts)
want_close = True
else:
want_close = False
try:
if sorted:
names = self.keys()
names.sort()
else:
names = self.iterkeys()
for n in names:
l = self[n].to_text(n, origin=self.origin,
relativize=relativize)
if nl is None:
print >> f, l
else:
f.write(l)
f.write(nl)
finally:
if want_close:
f.close()
def check_origin(self):
"""Do some simple checking of the zone's origin.
@raises dns.zone.NoSOA: there is no SOA RR
@raises dns.zone.NoNS: there is no NS RRset
@raises KeyError: there is no origin node
"""
if self.relativize:
name = dns.name.empty
else:
name = self.origin
if self.get_rdataset(name, dns.rdatatype.SOA) is None:
raise NoSOA
if self.get_rdataset(name, dns.rdatatype.NS) is None:
raise NoNS
class _MasterReader(object):
"""Read a DNS master file
@ivar tok: The tokenizer
@type tok: dns.tokenizer.Tokenizer object
@ivar ttl: The default TTL
@type ttl: int
@ivar last_name: The last name read
@type last_name: dns.name.Name object
@ivar current_origin: The current origin
@type current_origin: dns.name.Name object
@ivar relativize: should names in the zone be relativized?
@type relativize: bool
@ivar zone: the zone
@type zone: dns.zone.Zone object
@ivar saved_state: saved reader state (used when processing $INCLUDE)
@type saved_state: list of (tokenizer, current_origin, last_name, file)
tuples.
@ivar current_file: the file object of the $INCLUDed file being parsed
(None if no $INCLUDE is active).
@ivar allow_include: is $INCLUDE allowed?
@type allow_include: bool
@ivar check_origin: should sanity checks of the origin node be done?
The default is True.
@type check_origin: bool
"""
def __init__(self, tok, origin, rdclass, relativize, zone_factory=Zone,
allow_include=False, check_origin=True):
if isinstance(origin, (str, unicode)):
origin = dns.name.from_text(origin)
self.tok = tok
self.current_origin = origin
self.relativize = relativize
self.ttl = 0
self.last_name = None
self.zone = zone_factory(origin, rdclass, relativize=relativize)
self.saved_state = []
self.current_file = None
self.allow_include = allow_include
self.check_origin = check_origin
def _eat_line(self):
while 1:
(ttype, t) = self.tok.get()
if ttype == dns.tokenizer.EOL or ttype == dns.tokenizer.EOF:
break
def _rr_line(self):
"""Process one line from a DNS master file."""
# Name
if self.current_origin is None:
raise UnknownOrigin
token = self.tok.get(want_leading = True)
if token[0] != dns.tokenizer.WHITESPACE:
self.last_name = dns.name.from_text(token[1], self.current_origin)
else:
token = self.tok.get()
if token[0] == dns.tokenizer.EOL or \
token[0] == dns.tokenizer.EOF:
# treat leading WS followed by EOL/EOF as if they were EOL/EOF.
return
self.tok.unget(token)
name = self.last_name
if not name.is_subdomain(self.zone.origin):
self._eat_line()
return
if self.relativize:
name = name.relativize(self.zone.origin)
token = self.tok.get()
if token[0] != dns.tokenizer.IDENTIFIER:
raise dns.exception.SyntaxError
# TTL
try:
ttl = dns.ttl.from_text(token[1])
token = self.tok.get()
if token[0] != dns.tokenizer.IDENTIFIER:
raise dns.exception.SyntaxError
except dns.ttl.BadTTL:
ttl = self.ttl
# Class
try:
rdclass = dns.rdataclass.from_text(token[1])
token = self.tok.get()
if token[0] != dns.tokenizer.IDENTIFIER:
raise dns.exception.SyntaxError
except dns.exception.SyntaxError:
raise dns.exception.SyntaxError
except:
rdclass = self.zone.rdclass
if rdclass != self.zone.rdclass:
raise dns.exception.SyntaxError, "RR class is not zone's class"
# Type
try:
rdtype = dns.rdatatype.from_text(token[1])
except:
raise dns.exception.SyntaxError, \
"unknown rdatatype '%s'" % token[1]
n = self.zone.nodes.get(name)
if n is None:
n = self.zone.node_factory()
self.zone.nodes[name] = n
try:
rd = dns.rdata.from_text(rdclass, rdtype, self.tok,
self.current_origin, False)
except dns.exception.SyntaxError:
# Catch and reraise.
(ty, va) = sys.exc_info()[:2]
raise ty, va
except:
# All exceptions that occur in the processing of rdata
# are treated as syntax errors. This is not strictly
# correct, but it is correct almost all of the time.
# We convert them to syntax errors so that we can emit
# helpful filename:line info.
(ty, va) = sys.exc_info()[:2]
raise dns.exception.SyntaxError, \
"caught exception %s: %s" % (str(ty), str(va))
rd.choose_relativity(self.zone.origin, self.relativize)
covers = rd.covers()
rds = n.find_rdataset(rdclass, rdtype, covers, True)
rds.add(rd, ttl)
def read(self):
"""Read a DNS master file and build a zone object.
@raises dns.zone.NoSOA: No SOA RR was found at the zone origin
@raises dns.zone.NoNS: No NS RRset was found at the zone origin
"""
try:
while 1:
token = self.tok.get(True, True)
if token[0] == dns.tokenizer.EOF:
if not self.current_file is None:
self.current_file.close()
if len(self.saved_state) > 0:
(self.tok,
self.current_origin,
self.last_name,
self.current_file,
self.ttl) = self.saved_state.pop(-1)
continue
break
elif token[0] == dns.tokenizer.EOL:
continue
elif token[0] == dns.tokenizer.COMMENT:
self.tok.get_eol()
continue
elif token[1][0] == '$':
u = token[1].upper()
if u == '$TTL':
token = self.tok.get()
if token[0] != dns.tokenizer.IDENTIFIER:
raise dns.exception.SyntaxError, "bad $TTL"
self.ttl = dns.ttl.from_text(token[1])
self.tok.get_eol()
elif u == '$ORIGIN':
self.current_origin = self.tok.get_name()
self.tok.get_eol()
if self.zone.origin is None:
self.zone.origin = self.current_origin
elif u == '$INCLUDE' and self.allow_include:
token = self.tok.get()
if token[0] != dns.tokenizer.QUOTED_STRING:
raise dns.exception.SyntaxError, \
"bad filename in $INCLUDE"
filename = token[1]
token = self.tok.get()
if token[0] == dns.tokenizer.IDENTIFIER:
new_origin = dns.name.from_text(token[1], \
self.current_origin)
self.tok.get_eol()
elif token[0] != dns.tokenizer.EOL and \
token[0] != dns.tokenizer.EOF:
raise dns.exception.SyntaxError, \
"bad origin in $INCLUDE"
else:
new_origin = self.current_origin
self.saved_state.append((self.tok,
self.current_origin,
self.last_name,
self.current_file,
self.ttl))
self.current_file = file(filename, 'r')
self.tok = dns.tokenizer.Tokenizer(self.current_file,
filename)
self.current_origin = new_origin
else:
raise dns.exception.SyntaxError, \
"Unknown master file directive '" + u + "'"
continue
self.tok.unget(token)
self._rr_line()
except dns.exception.SyntaxError, detail:
(filename, line_number) = self.tok.where()
if detail is None:
detail = "syntax error"
raise dns.exception.SyntaxError, \
"%s:%d: %s" % (filename, line_number, detail)
# Now that we're done reading, do some basic checking of the zone.
if self.check_origin:
self.zone.check_origin()
def from_text(text, origin = None, rdclass = dns.rdataclass.IN,
relativize = True, zone_factory=Zone, filename=None,
allow_include=False, check_origin=True):
"""Build a zone object from a master file format string.
@param text: the master file format input
@type text: string.
@param origin: The origin of the zone; if not specified, the first
$ORIGIN statement in the master file will determine the origin of the
zone.
@type origin: dns.name.Name object or string
@param rdclass: The zone's rdata class; the default is class IN.
@type rdclass: int
@param relativize: should names be relativized? The default is True
@type relativize: bool
@param zone_factory: The zone factory to use
@type zone_factory: function returning a Zone
@param filename: The filename to emit when describing where an error
occurred; the default is '<string>'.
@type filename: string
@param allow_include: is $INCLUDE allowed?
@type allow_include: bool
@param check_origin: should sanity checks of the origin node be done?
The default is True.
@type check_origin: bool
@raises dns.zone.NoSOA: No SOA RR was found at the zone origin
@raises dns.zone.NoNS: No NS RRset was found at the zone origin
@rtype: dns.zone.Zone 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().
if filename is None:
filename = '<string>'
tok = dns.tokenizer.Tokenizer(text, filename)
reader = _MasterReader(tok, origin, rdclass, relativize, zone_factory,
allow_include=allow_include,
check_origin=check_origin)
reader.read()
return reader.zone
def from_file(f, origin = None, rdclass = dns.rdataclass.IN,
relativize = True, zone_factory=Zone, filename=None,
allow_include=True, check_origin=True):
"""Read a master file and build a zone object.
@param f: file or string. If I{f} is a string, it is treated
as the name of a file to open.
@param origin: The origin of the zone; if not specified, the first
$ORIGIN statement in the master file will determine the origin of the
zone.
@type origin: dns.name.Name object or string
@param rdclass: The zone's rdata class; the default is class IN.
@type rdclass: int
@param relativize: should names be relativized? The default is True
@type relativize: bool
@param zone_factory: The zone factory to use
@type zone_factory: function returning a Zone
@param filename: The filename to emit when describing where an error
occurred; the default is '<file>', or the value of I{f} if I{f} is a
string.
@type filename: string
@param allow_include: is $INCLUDE allowed?
@type allow_include: bool
@param check_origin: should sanity checks of the origin node be done?
The default is True.
@type check_origin: bool
@raises dns.zone.NoSOA: No SOA RR was found at the zone origin
@raises dns.zone.NoNS: No NS RRset was found at the zone origin
@rtype: dns.zone.Zone 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):
if filename is None:
filename = f
f = file(f, opts)
want_close = True
else:
if filename is None:
filename = '<file>'
want_close = False
try:
z = from_text(f, origin, rdclass, relativize, zone_factory,
filename, allow_include, check_origin)
finally:
if want_close:
f.close()
return z
def from_xfr(xfr, zone_factory=Zone, relativize=True):
"""Convert the output of a zone transfer generator into a zone object.
@param xfr: The xfr generator
@type xfr: generator of dns.message.Message objects
@param relativize: should names be relativized? The default is True.
It is essential that the relativize setting matches the one specified
to dns.query.xfr().
@type relativize: bool
@raises dns.zone.NoSOA: No SOA RR was found at the zone origin
@raises dns.zone.NoNS: No NS RRset was found at the zone origin
@rtype: dns.zone.Zone object
"""
z = None
for r in xfr:
if z is None:
if relativize:
origin = r.origin
else:
origin = r.answer[0].name
rdclass = r.answer[0].rdclass
z = zone_factory(origin, rdclass, relativize=relativize)
for rrset in r.answer:
znode = z.nodes.get(rrset.name)
if not znode:
znode = z.node_factory()
z.nodes[rrset.name] = znode
zrds = znode.find_rdataset(rrset.rdclass, rrset.rdtype,
rrset.covers, True)
zrds.update_ttl(rrset.ttl)
for rd in rrset:
rd.choose_relativity(z.origin, relativize)
zrds.add(rd)
z.check_origin()
return z