dnsjava v1.2

http://www.xbill.org/dnsjava

Author:

Brian Wellington (bwelling@xbill.org)
March 10, 2001

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 an
authoritative only server.  It supports TSIG authenticated messages, partial
DNSSEC verification, and EDNS0.

dnsjava provides functionality above and beyond that of the InetAddress class.
Since it is written in pure Java, dnsjava is fully threadsafe.

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 DNS interoperability
testing.  The high level API and caching resolver were added to make it useful
to a wider audience.  The authoritative only server was added as proof of
concept.


Getting started:

Run 'make' from the toplevel directory to build dnsjava.  JDK 1.1 or higher is
required.  If using JDK 1.1, ignore the deprecation warning.

To compile dnssec support (org.xbill.DNS.security), JDK 1.2 or higher and the
Java Cryptography Extensions are required.  Run 'make dnssec' to compile this
package.  TSIG support is separate from dnssec support, and does not require
'make dnssec'.

Limitations:

There's no way to determine what the local nameserver is at runtime from within
the JVM.  First, the property 'dns.server' (a comma delimited list) is
checked.  These can either be IP addresses or hostnames (which are 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 nameservers.  If
the underlying OS is Windows, winipcfg/ipconfig can be called and the output
parsed.  Otherwise, or if these attempts fail, the default nameserver is
"localhost".  This is unavoidable.  Unfortunately, I have no idea how to
determine the nameserver under MacOS or any other OSes.  Contributions of code
are welcome (see org/xbill/DNS/FindServer.java for the basic structure).

On 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.  This breaks the (mostly
undocumented) feature that the @me@ variable can be used in the textual form
of an A record to indicate the local address.  If InetAddress.getLocalHost()
doesn't work, dnsjava will print an error and die.  I don't know of a way to
fix this without using JNI.

Not all of the record types are supported.  Most types that are not supported
are either deprecated or rarely used.  Adding support for a new type is not
difficult, and requires no changes to any existing files.  If you want to see
a new type supported, send a patch or just ask.


Additional documentation:

Javadoc (1.2) documentation is provided in the doc/ subdirectory.


License:

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