dnsjava

http://www.xbill.org/dnsjava

Author:

Brian Wellington (bwelling@xbill.org)


Overview:

dnsjava is an implementation of DNS in Java.  It supports all of the common
record types and the DNSSEC types.  It can be used for queries, zone transfers,
and dynamic updates.  It includes a cache which can be used by clients, and a
(far from complete) implementation of a server.  It supports TSIG authenticated
messages (if you don't know, don't worry about it).

dnsjava was started as an excuse to learn Java.  It was useful for testing new
features in BIND without rewriting the C resolver.  It was then cleaned up and
extended in order to be used as a testing framework for the DNS
interoperability testing at the 44th IETF.  The high level API was added to
make it useful to a wider audience.

dnsjava is far from complete.  It should support the rest of the record types,
even though most are deprecated and/or rarely used.  It should handle
exceptions in more places, and probably define exceptions of its own.


Limitations:

There's no way to determine what the local nameserver is at runtime from within
the JVM.  First, the property 'dns.resolver' is checked.  This can either be an
IP address or a hostname (which is resolved using Java's built in DNS support).
If the underlying OS is unix-based, the dnsjava package can parse
/etc/resolv.conf and determine the nameserver.  If the property is not defined
and the OS is not unix-based, the default nameserver is "localhost".  This is
very bad.  Unfortuantely, I have no idea how to determine the nameserver under
Windows, MacOS, etc.  Contributions of code are welcome (see
DNS/FindResolver.java for the basic structure).

One some machines, InetAddress.getLocalHost() returns 127.0.0.1.  This is
usually caused by a bug in the JVM, and often happens when the machine has
a dynamic address and its hostname is not in DNS.  If the @me@ variable
is present in the textual form of an A record and InetAddress.getLocalHost()
doesn't work, dnsjava will print an error and die.  I'm investigating
ways to improve this behavior without using JNI.


Future:

- A GUI for the dynamic update program would be nice
- javadoc documentation


License:

dnsjava is placed under the GNU General Public License (GPL).  However,
usage under additional licenses may be granted by the author.