Java Reference
In-Depth Information
Example 6−3: SecureService.java (continued)
out.println("Opened file for writing: " + f);
}
catch (Exception e) { out.println("Failed: " + e); }
// Check whether we've been given permision to read files from
// the tmpdir directory
out.println();
out.println("Attempting to read from " + tmpdir + "...");
try {
FileReader in = new FileReader(f);
out.println("Opened file for reading: " + f);
}
catch (Exception e) { out.println("Failed: " + e); }
}
catch (Exception e) { out.println("Failed: " + e); }
// Close the Service sockets
out.close();
i.close();
}
}
To test
SafeServer
with the
SecureService
class, you have to decide which direc-
tories you'll use for storing the service classes and for the scratch directory. In the
material that follows, I've used
/tmp/services
and
/tmp/scratch
as the directory
names.
First, compile
SecureService
using the
-d
option to tell
javac
where to put the
resulting class file:
% javac -d /tmp/services SecureService.java
It is important that you make sure there isn't a copy of the
Secur eService.class
file
in the current directory or anywhere else that Java might find it in the local class
path. If the
URLClassLoader
can find the class locally, it won't bother loading it
through the URL you specify.
Now, to run the
SafeServer
class, specify the name of the
SecureService
class,
the URL to load it from, the port to listen for connections on, and four different
system properties with
-D
options:
% java -Djava.security.manager -Djava.security.policy=SafeServer.policy \
-Dservice.dir=/tmp/services -Dservice.tmp=/tmp/scratch \
com.davidflanagan.examples.security.SafeServer file:/tmp/services/ \
SecureService 4000
This is a complicated command line, but it produces the desired results. When you
connect to port 4000, you get the following output from the service:
% java com.davidflanagan.examples.net.GenericClient localhost 4000
Connected to localhost/127.0.0.1:4000
Trying to create and install a security manager...
Failed: java.security.AccessControlException: access denied
(java.lang.RuntimePermission createSecurityManager)
Trying to exit...
Failed: java.security.AccessControlException: access denied
