What I Learned Today » ant http://christiansons.net/mike/blog Mike Christianson's journal of Java, Ant, SVN, Jetty, cygwin and other stuff. Wed, 04 Aug 2010 22:24:04 +0000 en hourly 1 http://wordpress.org/?v=3.0.1 Obfuscating a webapp .war file with yGuard and Ant http://christiansons.net/mike/blog/2009/02/obfuscating-a-webapp-war-file-with-yguard-and-ant/ http://christiansons.net/mike/blog/2009/02/obfuscating-a-webapp-war-file-with-yguard-and-ant/#comments Thu, 05 Feb 2009 19:07:03 +0000 Mike Christianson http://blog.christiansons.net/?p=178 One way to protect Java software from casual reverse engineering is obfuscation. Essentially, an obfuscator renames classes, variables, and packages with random/meaningless names. The application still functions correctly; the decompiled code becomes difficult to read.

There are quite a few obfuscators for Java — at least a dozen when I looked — most of which are easily used from an Ant script.

For my use I selected one with a ready-to-use Ant task: yGuard. Unfortunately, yGuard operates on .jar files only, not individual .class files or webapp .war files. Thus, I have written my own Ant script which uses yGuard and built-in Ant tasks to obfuscate .war files.

Before you try using my Ant script, read yGuard’s documentation and be sure you fully understand how it works. You should pay special attention to the inoutpairs, keep, and hints and troubleshooting sections.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73

<!-- prepare a temporary directory in which the war file is expanded and obfuscated -->
<tempfile property="unwar.dir" destdir="${java.io.tmpdir}" deleteonexit="yes"/>
<mkdir dir="${unwar.dir}"/>
<unwar src="webapp.war" dest="${unwar.dir}"/>
 
<!-- create a jar of webapp classes (required by yguard) for obfuscation -->
<jar destfile="${unwar.dir}/WEB-INF/lib/webapp.jar" whenempty="fail">
    <zipfileset dir="${unwar.dir}/WEB-INF/classes"/>
</jar>
<delete dir="${unwar.dir}/WEB-INF/classes"/>
 
<!-- create a fileset of internal libraries to be obfuscated -->
<fileset dir="${unwar.dir}/WEB-INF/lib" id="internal.lib.set">
    <include name="myLibrary.jar"/>
    <include name="myOtherLibrary.jar"/>
</fileset>
 
<!-- move the internal libraries to a temporary directory and make a fileset out of them -->
<tempfile property="obfuscation.dir" destDir="${java.io.tmpdir}" deleteonexit="yes"/>
<mkdir dir="${obfuscation.dir}"/>
<move todir="${obfuscation.dir}">
    <fileset refid="internal.lib.set"/>
</move>
 
<!-- create a jar of web.xml (required by yguard) for obfuscation -->
<jar destfile="${obfuscation.dir}/web.xml.jar" whenempty="fail">
    <zipfileset dir="${unwar.dir}/WEB-INF" includes="web.xml"/>
</jar>
<delete file="${unwar.dir}/WEB-INF/web.xml"/>
 
<!-- make a fileset of all jars to be obfuscated -->
<fileset dir="${obfuscation.dir}" includes="*.jar" id="in-out.set"/>
 
<!-- make a fileset of the remaining libraries, these are not obfuscated -->
<path id="external.lib.path">
    <fileset dir="${unwar.dir}/WEB-INF/lib" includes="*.jar"/>
</path>
 
<taskdef name="yguard"
    classname="com.yworks.yguard.YGuardTask"
    classpath="yguard.jar"/>
 
<yguard>
    <inoutpairs>
        <!-- these filesets are inputs to be obfuscated -->
        <fileset refid="in-out.set"/>
    </inoutpairs>
    <externalclasses refid="external.lib.path"/>  <!-- external libs, not obfuscated -->
    <rename>
        <adjust replaceContent="true">
            <include name="web.xml"/>  <!-- modified to reference the obfuscated Servlet -->
        </adjust>
        <keep>
            <!-- classes, packages, methods, and fields which should not obfuscated are specified here -->
        </keep>
    </rename>
</yguard>
 
<!-- move our newly obfuscated classes back into the lib area -->
<move todir="${unwar.dir}/WEB-INF/lib">
    <fileset dir="${obfuscation.dir}" includes="*_obf.jar"/>
</move>
 
<!-- unjar the adjusted web.xml --> 
<unzip dest="${unwar.dir}/WEB-INF/" src="${unwar.dir}/WEB-INF/lib/web.xml_obf.jar">
    <patternset includes="web.xml"/>
</unzip>
<delete>
    <fileset dir="${unwar.dir}/WEB-INF/lib" includes="web.xml*.jar"/>
</delete>
 
<!-- rebuild the war file -->
<war destfile="webapp_obf.war" basedir="${unwar.dir}"/>

yWorks, the creator of yGuard, is perhaps best known for yDoc a UML diagram generator for JavaDocs.

]]> http://christiansons.net/mike/blog/2009/02/obfuscating-a-webapp-war-file-with-yguard-and-ant/feed/ 3 Automate Advanced Installer with Ant http://christiansons.net/mike/blog/2009/01/automate-advanced-installer-with-ant/ http://christiansons.net/mike/blog/2009/01/automate-advanced-installer-with-ant/#comments Thu, 29 Jan 2009 05:04:13 +0000 Mike Christianson http://blog.christiansons.net/?p=106 Note: this post was updated in light of discussion on the Advanced Installer forum.

At work, we use Advanced Installer to create easy-to-use Windows installers for internal and external customers. I wrote a short Ant script for building the installer to save time and minimize mistakes.

If you use Advanced Installer with your Java projects, be sure to read my post on using the Advanced Installer licensing feature within a Java application.

Here is a partial Ant script for executing Advanced Installer builds. It’s not fancy, but it gets the job done. Notice the script has two parts — one for setting the version number of the product and another for doing the actual build.

1
2
3
4
5
6
7
8
9
10
11
12
13
14

<property name="installer.command" location="C:/Caphyon/Advanced Installer/AdvancedInstaller.com"/>
<property name="filename" location="C:/build/product.aip"/>
 
<exec executable="${installer.command}" failonerror="yes">
    <arg value="/edit"/>
    <arg value="${filename}"/>
    <arg value="/SetVersion"/>
    <arg value="${installerVersion}"/>
</exec>
 
<exec executable="${installer.command}" failonerror="yes">
    <arg value="/build"/>
    <arg value="${filename}"/>
</exec>

In the next snippet, which should be executed first, I’ve made the version number dynamic based on the current time, day, and month (but not year)! (The pattern may seem a little odd; it conforms to what Windows Installer expects.) Of course, this is completely optional and can be overridden using Ant command-line properties.

1
2
3

<tstamp>
    <format property="installerVersion" pattern="MM.dd.HHmm"/>
</tstamp>

When this script is combined with continuous integration, we have a repeatable, consistent, fully automated build of our software and its installer. And that rocks.

]]> http://christiansons.net/mike/blog/2009/01/automate-advanced-installer-with-ant/feed/ 0 Ant on Ubuntu without GCJ http://christiansons.net/mike/blog/2009/01/ant-on-ubuntu-without-gcj/ http://christiansons.net/mike/blog/2009/01/ant-on-ubuntu-without-gcj/#comments Fri, 02 Jan 2009 22:23:33 +0000 Mike Christianson http://blog.christiansons.net/?p=76 You may be surprised to learn Ant requires GCJ when installed through Synaptic or apt on Ubuntu.  GCJ is GNU’s Java compiler.  When you’re using Sun’s JDK and compiler, GCJ can get in the way — at worst it creates conflicts; at best it causes confusion.

Here’s how I installed Ant on Ubuntu without GCJ. Be sure to check out (easier) alternatives suggested in the comments, below.

  1. Download the current .tar.bz2 distribution of Ant from http://www.ibiblio.org/pub/mirrors/apache/ant/binaries/.
  2. Unpack archive using tar.
    3. tar -xjvf apache-ant-*-bin.tar.bz2
  3. Move the unpacked directory to /usr/local/ant.
  4. Change that directory’s owner to root.
    5. chown -R root:root /usr/local/ant
  5. Add the following lines to /etc/bash.bashrc.
    6. export ANT_HOME=/usr/local/ant
export PATH=${PATH}:${ANT_HOME}/bin

From a new shell, run ant. You should see the following:

Buildfile: build.xml does not exist!
Build failed

Yes, it’s a failure message. But it means Ant is working as expected. :)

]]> http://christiansons.net/mike/blog/2009/01/ant-on-ubuntu-without-gcj/feed/ 4