Monthly Archives: August 2014

Music from Our Tube; Tom Vek in the Jungle

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Tom Vek is an English multi-instrumentalist, but you could just as well read the Wikipedia-article if you want to know that and more. If, instead, you’d prefer to hear what he sounds like, you can listen (and watch) below video of “Sherman (Animals in the Jungle)”;

Tom Vek - Sherman (Animals in the Jungle)
Watch this video on YouTube.

(When) should you Try/Catch Javascript?

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Autoptimize comes with a “Add try-catch wrapping?”-option, which wraps every aggregated script in a try-catch-block, to avoid an error in one script to block the others.

I considered enabling this option by default, as it would prevent JS optimization occasionally breaking sites badly. I discussed this with a number of smart people and searched the web, eventually stumbling on this blogpost which offers an alternative for try-catch because;

Some JavaScript engines, such as V8 (Chrome) do not optimize functions that make use of a try/catch block as the optimizing compiler will skip it when encountered. No matter what context you use a try/catch block in, there will always be an inherent performance hit, quite possibly a substantial one. [Testcases] confirm [that] not only is there up to a 90% loss in performance when no error even occurs, but the declination is significantly greater when an error is raised and control enters the catch block.

So given this damning evidence of severe performance degradation, “try/catch wrapping” will not be enabled by default and although Ryan’s alternative approach has its merits, I’m weary of the caveats so I won’t include that (for now anyway). If your site breaks when enabling JS optimization in Autoptimize, you can enable try/catch wrapping as a quick workaround, but finding the offending script and excluding it from being optimized is clearly the better solution.

Next Autoptimize eliminates render-blocking CSS in above-the-fold content

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Although current versions of Autoptimize can already tackle Google PageSpeed Insights’ “Eliminate render-blocking CSS in above-the-fold content” tip, the next release will allow you to do so in an even better way. As from version 1.9 you’ll be able to combine the best of both “inline CSS” and “defer CSS” worlds. “Defer” effectively becomes “Inline and defer“, allowing you to specify the “above the fold CSS” which is then inlined in the head of your HTML, while your normal autoptimized CSS is deferred until the page has finished loading.

Other improvements in the upcoming Autoptimize 1.9.0 include:

  • Inlined Base64-encoded background Images will now be cached as well and the threshold for inlining these images has been bumped up to 4096 bytes (from 2560).
  • Separate cache-directories for CSS and JS in /wp-content/cache/autoptimize, which should result in faster cache pruning (and in some cases possibly faster serving of individual aggregated files).
  • CSS is now added before the <title>-tag, JS before </body> (and after </title> when forced in head). This can be overridden in the API.
  • Some usability Improvements of the administration-page
  • Multiple hooks added to the API a.o. filters to not aggregate inline CSS or JS and filters to aggregate but not minify CSS or JS.
  • Multiple bugfixes & improvements

On the todo-list; testing, some translation updates (I’ll contact you translators in the coming week) and updating the readme.txt.

The first test-version of what will become 1.9.0 (still tagged 1.8.5 for now though) has been committed to wordpress.org’s plugin SVN and can be downloaded here. Anyone wanting to help out testing this new release, go and grab your copy and provide me with feedback.

My Adventures on OpenShift

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openshiftI have always been a fan of Red Hat, even if have never used their products extensively. They were one of the original movers in Linux-market back when Slackware was big and when InfoMagic CD-rom boxes with multiple distro’s were popular. And I have remained a fan because they succeeded in building a solid company built on and around open source & services.

So I was very happy to read that Red Hat had entered the PAAS-market with OpenShift, that that platform was built on open source(d) solutions and that a small-timer like me could deploy apps for free on their application cloud. I signed up, installed the WordPress instant application, added some tried & tested plugins and imported my content. Half an hour works, tops and performance proved to be great. Everything was just peachy, until I received this message in my mailbox;

We believe your use of OpenShift violates the Services Agreement and Acceptable Use Policy both of which can be found here: https://openshift.redhat.com/app/legal/

Infected file(s):
/var/lib/openshift53bcc3fd5973cabac00000d1/.tmp/53bcc3fd5973cabac00000d1/just_test_bc: Perl.Shellbot-8

And ZAP, my application was removed. As I had no idea how “just_test_bc” ended up in a temp-folder, the only possibility was a successful hack-attempt, so I contacted the security team to get more information. It took some time (and an escalation via the Customer Enablement Team), but I eventually got in touch with Stefanie at Red Hat, who was able to provide me with more information:

It looks like we had a one-off error in the script that emailed you. Your application was still flagged, but on a different file than we emailed about. This is the actual file:

/var/lib/openshift/53bd21435973cad637000080/mysql/data/ib_logfile0: PHP.ShellExec

So there was something in the mysql database log that set off the scan. […] It looks like mysql may have logged someone’s attempt to inject some bad PHP code into your app.

ib_logfiles are MySQL’s innodb replay log files and as Stefanie provided me with a tarball with my entire application, I extracted ib_logfile0 and used “strings” to extract readable information from the binary file. The result (from my mail to Stefanie);

Although php’s exec (and similar functions) can be found [in the logfile], this is always due to … blogposts about web security and specifically this one; http://blog.futtta.be/2007/12/02/php-security-eval-is-evil/. The content of that article was inserted in the DB and [thus] added to ib_logfile. Your scanner finds the content [in that innodb replay logfile] and flags this as a problem. I would think the OpenShift scanner needs some finetuning, [as now] anyone is at risk of having their app auto-removed if the mysql-redo-logfile happens to contain vaguely “offending” strings such as shell_exec?

OpenShift confirmed this analysis;

You’re absolutely right that our scanner needs work. So what I’m going to do is get you onto a whitelist so this thing doesn’t flag you again. […] All takedowns are currently on hold until I can implement pre-removal notifications [and] improve our standard operating procedure for this kind of thing. That should give people a chance to tell us that their apps are not malicious, so that we can whitelist others too, if needed. As long as they notice an email saying “OpenShift Terms Of Service Violation” within a few days, I think they should be safe. If they do get flagged as a false positive like your app did, they’ll email us back and let us know it’s a mistake, and then they’ll be added to the whitelist too.

Now wasn’t that an interesting adventure? If ever you get a notification-mail from OpenShift related to security issues, check if the problem isn’t with benign content being inserted in the database and if so be sure to contact OpenShift so they can add you to their whitelist.