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# Copyright (C) 2003-2007, 2009-2011 Nominum, Inc.
#
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# provided that the above copyright notice and this permission notice
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# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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"""DNS Dynamic Update Support"""
import dns.message
import dns.name
import dns.opcode
import dns.rdata
import dns.rdataclass
import dns.rdataset
import dns.tsig
class Update(dns.message.Message):
def __init__(self, zone, rdclass=dns.rdataclass.IN, keyring=None,
keyname=None, keyalgorithm=dns.tsig.default_algorithm):
"""Initialize a new DNS Update object.
@param zone: The zone which is being updated.
@type zone: A dns.name.Name or string
@param rdclass: The class of the zone; defaults to dns.rdataclass.IN.
@type rdclass: An int designating the class, or a string whose value
is the name of a class.
@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 keyalgorithm: The TSIG algorithm to use; defaults to
dns.tsig.default_algorithm. Constants for TSIG algorithms are defined
in dns.tsig, and the currently implemented algorithms are
HMAC_MD5, HMAC_SHA1, HMAC_SHA224, HMAC_SHA256, HMAC_SHA384, and
HMAC_SHA512.
@type keyalgorithm: string
"""
super(Update, self).__init__()
self.flags |= dns.opcode.to_flags(dns.opcode.UPDATE)
if isinstance(zone, (str, unicode)):
zone = dns.name.from_text(zone)
self.origin = zone
if isinstance(rdclass, str):
rdclass = dns.rdataclass.from_text(rdclass)
self.zone_rdclass = rdclass
self.find_rrset(self.question, self.origin, rdclass, dns.rdatatype.SOA,
create=True, force_unique=True)
if not keyring is None:
self.use_tsig(keyring, keyname, algorithm=keyalgorithm)
def _add_rr(self, name, ttl, rd, deleting=None, section=None):
"""Add a single RR to the update section."""
if section is None:
section = self.authority
covers = rd.covers()
rrset = self.find_rrset(section, name, self.zone_rdclass, rd.rdtype,
covers, deleting, True, True)
rrset.add(rd, ttl)
def _add(self, replace, section, name, *args):
"""Add records. The first argument is the replace mode. If
false, RRs are added to an existing RRset; if true, the RRset
is replaced with the specified contents. The second
argument is the section to add to. The third argument
is always a name. The other arguments can be:
- rdataset...
- ttl, rdata...
- ttl, rdtype, string..."""
if isinstance(name, (str, unicode)):
name = dns.name.from_text(name, None)
if isinstance(args[0], dns.rdataset.Rdataset):
for rds in args:
if replace:
self.delete(name, rds.rdtype)
for rd in rds:
self._add_rr(name, rds.ttl, rd, section=section)
else:
args = list(args)
ttl = int(args.pop(0))
if isinstance(args[0], dns.rdata.Rdata):
if replace:
self.delete(name, args[0].rdtype)
for rd in args:
self._add_rr(name, ttl, rd, section=section)
else:
rdtype = args.pop(0)
if isinstance(rdtype, str):
rdtype = dns.rdatatype.from_text(rdtype)
if replace:
self.delete(name, rdtype)
for s in args:
rd = dns.rdata.from_text(self.zone_rdclass, rdtype, s,
self.origin)
self._add_rr(name, ttl, rd, section=section)
def add(self, name, *args):
"""Add records. The first argument is always a name. The other
arguments can be:
- rdataset...
- ttl, rdata...
- ttl, rdtype, string..."""
self._add(False, self.authority, name, *args)
def delete(self, name, *args):
"""Delete records. The first argument is always a name. The other
arguments can be:
- I{nothing}
- rdataset...
- rdata...
- rdtype, [string...]"""
if isinstance(name, (str, unicode)):
name = dns.name.from_text(name, None)
if len(args) == 0:
rrset = self.find_rrset(self.authority, name, dns.rdataclass.ANY,
dns.rdatatype.ANY, dns.rdatatype.NONE,
dns.rdatatype.ANY, True, True)
elif isinstance(args[0], dns.rdataset.Rdataset):
for rds in args:
for rd in rds:
self._add_rr(name, 0, rd, dns.rdataclass.NONE)
else:
args = list(args)
if isinstance(args[0], dns.rdata.Rdata):
for rd in args:
self._add_rr(name, 0, rd, dns.rdataclass.NONE)
else:
rdtype = args.pop(0)
if isinstance(rdtype, (str, unicode)):
rdtype = dns.rdatatype.from_text(rdtype)
if len(args) == 0:
rrset = self.find_rrset(self.authority, name,
self.zone_rdclass, rdtype,
dns.rdatatype.NONE,
dns.rdataclass.ANY,
True, True)
else:
for s in args:
rd = dns.rdata.from_text(self.zone_rdclass, rdtype, s,
self.origin)
self._add_rr(name, 0, rd, dns.rdataclass.NONE)
def replace(self, name, *args):
"""Replace records. The first argument is always a name. The other
arguments can be:
- rdataset...
- ttl, rdata...
- ttl, rdtype, string...
Note that if you want to replace the entire node, you should do
a delete of the name followed by one or more calls to add."""
self._add(True, self.authority, name, *args)
def present(self, name, *args):
"""Require that an owner name (and optionally an rdata type,
or specific rdataset) exists as a prerequisite to the
execution of the update. The first argument is always a name.
The other arguments can be:
- rdataset...
- rdata...
- rdtype, string..."""
if isinstance(name, (str, unicode)):
name = dns.name.from_text(name, None)
if len(args) == 0:
rrset = self.find_rrset(self.answer, name,
dns.rdataclass.ANY, dns.rdatatype.ANY,
dns.rdatatype.NONE, None,
True, True)
elif isinstance(args[0], dns.rdataset.Rdataset) or \
isinstance(args[0], dns.rdata.Rdata) or \
len(args) > 1:
if not isinstance(args[0], dns.rdataset.Rdataset):
# Add a 0 TTL
args = list(args)
args.insert(0, 0)
self._add(False, self.answer, name, *args)
else:
rdtype = args[0]
if isinstance(rdtype, (str, unicode)):
rdtype = dns.rdatatype.from_text(rdtype)
rrset = self.find_rrset(self.answer, name,
dns.rdataclass.ANY, rdtype,
dns.rdatatype.NONE, None,
True, True)
def absent(self, name, rdtype=None):
"""Require that an owner name (and optionally an rdata type) does
not exist as a prerequisite to the execution of the update."""
if isinstance(name, (str, unicode)):
name = dns.name.from_text(name, None)
if rdtype is None:
rrset = self.find_rrset(self.answer, name,
dns.rdataclass.NONE, dns.rdatatype.ANY,
dns.rdatatype.NONE, None,
True, True)
else:
if isinstance(rdtype, (str, unicode)):
rdtype = dns.rdatatype.from_text(rdtype)
rrset = self.find_rrset(self.answer, name,
dns.rdataclass.NONE, rdtype,
dns.rdatatype.NONE, None,
True, True)
def to_wire(self, origin=None, max_size=65535):
"""Return a string containing the update in DNS compressed wire
format.
@rtype: string"""
if origin is None:
origin = self.origin
return super(Update, self).to_wire(origin, max_size)