# Copyright (C) 2001-2007, 2009-2011 Nominum, Inc.
#
# Permission to use, copy, modify, and distribute this software and its
# documentation for any purpose with or without fee is hereby granted,
# provided that the above copyright notice and this permission notice
# appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND NOMINUM DISCLAIMS ALL WARRANTIES
# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NOMINUM BE LIABLE FOR
# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
# OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
"""DNS nodes. A node is a set of rdatasets."""
from io import StringIO
import dns.rdataset
import dns.rdatatype
import dns.renderer
class Node(object):
"""A DNS node.
A node is a set of rdatasets
@ivar rdatasets: the node's rdatasets
@type rdatasets: list of dns.rdataset.Rdataset objects"""
__slots__ = ['rdatasets']
def __init__(self):
"""Initialize a DNS node.
"""
self.rdatasets = []
def to_text(self, name, **kw):
"""Convert a node to text format.
Each rdataset at the node is printed. Any keyword arguments
to this method are passed on to the rdataset's to_text() method.
@param name: the owner name of the rdatasets
@type name: dns.name.Name object
@rtype: string
"""
s = StringIO()
for rds in self.rdatasets:
if len(rds) > 0:
s.write(rds.to_text(name, **kw))
s.write(u'\n')
return s.getvalue()[:-1]
def __repr__(self):
return '<DNS node ' + str(id(self)) + '>'
def __eq__(self, other):
"""Two nodes are equal if they have the same rdatasets.
@rtype: bool
"""
#
# This is inefficient. Good thing we don't need to do it much.
#
for rd in self.rdatasets:
if rd not in other.rdatasets:
return False
for rd in other.rdatasets:
if rd not in self.rdatasets:
return False
return True
def __ne__(self, other):
return not self.__eq__(other)
def __len__(self):
return len(self.rdatasets)
def __iter__(self):
return iter(self.rdatasets)
def find_rdataset(self, rdclass, rdtype, covers=dns.rdatatype.NONE,
create=False):
"""Find an rdataset matching the specified properties in the
current node.
@param rdclass: The class of the rdataset
@type rdclass: int
@param rdtype: The type of the rdataset
@type rdtype: int
@param covers: The covered type. Usually this value is
dns.rdatatype.NONE, but if the rdtype is dns.rdatatype.SIG or
dns.rdatatype.RRSIG, then the covers value will be the rdata
type the SIG/RRSIG covers. The library treats the SIG and RRSIG
types as if they were a family of
types, e.g. RRSIG(A), RRSIG(NS), RRSIG(SOA). This makes RRSIGs much
easier to work with than if RRSIGs covering different rdata
types were aggregated into a single RRSIG rdataset.
@type covers: int
@param create: If True, create the rdataset if it is not found.
@type create: bool
@raises KeyError: An rdataset of the desired type and class does
not exist and I{create} is not True.
@rtype: dns.rdataset.Rdataset object
"""
for rds in self.rdatasets:
if rds.match(rdclass, rdtype, covers):
return rds
if not create:
raise KeyError
rds = dns.rdataset.Rdataset(rdclass, rdtype)
self.rdatasets.append(rds)
return rds
def get_rdataset(self, rdclass, rdtype, covers=dns.rdatatype.NONE,
create=False):
"""Get an rdataset matching the specified properties in the
current node.
None is returned if an rdataset of the specified type and
class does not exist and I{create} is not True.
@param rdclass: The class of the rdataset
@type rdclass: int
@param rdtype: The type of the rdataset
@type rdtype: int
@param covers: The covered type.
@type covers: int
@param create: If True, create the rdataset if it is not found.
@type create: bool
@rtype: dns.rdataset.Rdataset object or None
"""
try:
rds = self.find_rdataset(rdclass, rdtype, covers, create)
except KeyError:
rds = None
return rds
def delete_rdataset(self, rdclass, rdtype, covers=dns.rdatatype.NONE):
"""Delete the rdataset matching the specified properties in the
current node.
If a matching rdataset does not exist, it is not an error.
@param rdclass: The class of the rdataset
@type rdclass: int
@param rdtype: The type of the rdataset
@type rdtype: int
@param covers: The covered type.
@type covers: int
"""
rds = self.get_rdataset(rdclass, rdtype, covers)
if rds is not None:
self.rdatasets.remove(rds)
def replace_rdataset(self, replacement):
"""Replace an rdataset.
It is not an error if there is no rdataset matching I{replacement}.
Ownership of the I{replacement} object is transferred to the node;
in other words, this method does not store a copy of I{replacement}
at the node, it stores I{replacement} itself.
"""
if not isinstance(replacement, dns.rdataset.Rdataset):
raise ValueError('replacement is not an rdataset')
self.delete_rdataset(replacement.rdclass, replacement.rdtype,
replacement.covers)
self.rdatasets.append(replacement)
