Ignore AccessControlException while setting network stack system property

[christianbrensing]

Since 1.7.5 Ruby.java sets the system property java.net.preferIPv4Stackin its private method setNetworkStack(). If running with enabled java security (e.g. in a web application) this may fail, if the jruby domain has not been granted the appropiate PropertyPermission.

An easy fix would be to wrap the security related calls in a try-catch-block and ignore or log any thrown AccessControlException.

I made a fix locally, a working patch would look like this:

--- a/core/src/main/java/org/jruby/Ruby.java
+++ b/core/src/main/java/org/jruby/Ruby.java
@@ -131,6 +131,7 @@ import java.io.PrintStream;
 import java.lang.reflect.InvocationTargetException;
 import java.net.BindException;
 import java.nio.channels.ClosedChannelException;
+import java.security.AccessControlException;
 import java.security.SecureRandom;
 import java.util.*;
 import java.util.concurrent.Callable;
@@ -4493,10 +4494,16 @@ public final class Ruby {
     }

     private void setNetworkStack() {
-        if (config.getIPv4Preferred()) {
-            System.setProperty("java.net.preferIPv4Stack", "true");
-        } else {
-            System.setProperty("java.net.preferIPv4Stack", "false");
+        try {
+            if (config.getIPv4Preferred()) {
+                System.setProperty("java.net.preferIPv4Stack", "true");
+            } else {
+                System.setProperty("java.net.preferIPv4Stack", "false");
+            }
+        } catch (AccessControlException e) {
+            LOG.debug("unable to set network stack system property due to "
+                    + "security restrictions, please set it manually as JVM "
+                    + "parameter (-Djava.net.preferIPv4Stack=true|false)");
         }
     }

[BanzaiMan]

Do you mind turning this into a PR? That way, we can credit you for the fix. Thank you.

[christianbrensing]

Done, see PR 1125.