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node.py
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# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license # Copyright (C) 2001-2017 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 Node is a set of rdatasets.""" __slots__ = ['rdatasets'] def __init__(self): #: the set of rdatsets, represented as a list. 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. *name*, a ``dns.name.Name`` or ``text``, the owner name of the rdatasets. Returns a ``text``. """ 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): # # 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. *rdclass*, an ``int``, the class of the rdataset. *rdtype*, an ``int``, the type of the rdataset. *covers*, an ``int``, 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. *create*, a ``bool``. If True, create the rdataset if it is not found. Raises ``KeyError`` if an rdataset of the desired type and class does not exist and *create* is not ``True``. Returns a ``dns.rdataset.Rdataset``. """ 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 *create* is not ``True``. *rdclass*, an ``int``, the class of the rdataset. *rdtype*, an ``int``, the type of the rdataset. *covers*, an ``int``, 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. *create*, a ``bool``. If True, create the rdataset if it is not found. Returns a ``dns.rdataset.Rdataset`` 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. *rdclass*, an ``int``, the class of the rdataset. *rdtype*, an ``int``, the type of the rdataset. *covers*, an ``int``, the covered type. """ 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 *replacement*. Ownership of the *replacement* object is transferred to the node; in other words, this method does not store a copy of *replacement* at the node, it stores *replacement* itself. *replacement*, a ``dns.rdataset.Rdataset``. Raises ``ValueError`` if *replacement* is not a ``dns.rdataset.Rdataset``. """ 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)