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- # 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)
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