The PySubnetTree package provides a Python data structure SubnetTree which maps subnets given in CIDR notation (incl. corresponding IPv6 versions) to Python objects. Lookups are performed by longest-prefix matching.
You can find the latest PySubnetTree release for download at http://www.bro.org/download.
PySubnetTree’s git repository is located at git://git.bro.org/pysubnettree.git. You can browse the repository here.
This document describes PySubnetTree 0.23. See the CHANGES file for version history.
A simple example which associates CIDR prefixes with strings:
>>> import SubnetTree
>>> t = SubnetTree.SubnetTree()
>>> t["10.1.0.0/16"] = "Network 1"
>>> t["10.1.42.0/24"] = "Network 1, Subnet 42"
>>> print "10.1.42.1" in t
True
>>> print t["10.1.42.1"]
Network 1, Subnet 42
>>> print t["10.1.43.1"]
Network 1
>>> print "10.20.1.1" in t
False
>>> try:
... print t["10.20.1.1"]
... except KeyError, err:
... print "Error: %s not found" % err
Error: '10.20.1.1' not found
By default, CIDR prefixes and IP addresses are given as strings. Alternatively, a SubnetTree object can be switched into binary mode, in which single addresses are passed in the form of packed binary strings as, e.g., returned by socket.inet_aton:
>>> t.get_binary_lookup_mode()
False
>>> t.set_binary_lookup_mode(True)
>>> t.get_binary_lookup_mode()
True
>>> import socket
>>> print t[socket.inet_aton("10.1.42.1")]
Network 1, Subnet 42
A SubnetTree also provides methods insert(prefix,object=None) for insertion of prefixes (object can be skipped to use the tree like a set), and remove(prefix) for removing entries (remove performs an _exact_ match rather than longest-prefix).
Internally, the CIDR prefixes of a SubnetTree are managed by a Patricia tree data structure and lookups are therefore efficient even with a large number of prefixes.
PySubnetTree comes with a BSD license.
This package requires Python 2.4 or newer.
Installation is pretty simple:
> python setup.py install