Filtered blocking code from WhatsApp

Whatsapp's blocking code filtered

 

Someone commented on the blog some regular expression that was being used to block telegram on whatsapp’s APP:

 

“(\\W|\\b)telegram(\\.\\w+){1,2}\\z”.

So we wanted to probe that the blocking was not caused by a random glitch and there was an specific purpose of blocking Telegram links.

Firstly we downloaded the android APK directly from WhatsApp site: https://www.cdn.whatsapp.net/android/2.12.370/WhatsApp.apk

The code

The first surprise we noticed was that the apk is not obfuscated at all. So we used jadx to decompile it, and this is the result:

[Result of decompiling WhatsApp Version 2.12.370 (sha1: bf9c222b1acaa007d5e78a17ceace2bdd4d7d198) using jadx 0.6.0]

In the class LinkifyWeb.java we found the infamous regular expression:Whatsapp's blocking code filtered

This regular expression means: Look for “telegram” string not preceded by anything, or preceded by a word separator, or preceded by non-word-character, then followed by some kind of domain TLD.

And this is the code that calls the regular expression and blocks any telegram URL at Whatsapp APP:

Whatsapp's blocking code filtered

Every time someone sends an URL, this function analize it to see if the URL is a “badHost”.

So, this confirms that the blocking of telegram is not unintentional. It is crystal clear that WhatsApp targets Telegram and only Telegram specifically.

Bonus track: In their paranoia, whatsapp also blocked the domain telegram.com. That is not related with telegram.

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Daniel LaRusso

Daniel LaRusso

Engineer, developer, open source enthusiast, passionate for technology. Consultant and researcher in robotics and automation.

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4 Responses

  1. regex_master says:

    On top of doing abusive practices, they are bad coders.

    [\W\b]telegram(?:\.\w+){1,2}\z

    is almost twice faster.

    • Jaimehrubiks says:

      I’m so bad with regex, but how not to trust someone with your name 😛

    • bad_wolf says:

      Twice faster for something that’s called very sporadically. Not really worth it and in particular NOT a good measure of their value as coders.

  1. 1 December, 2015

    […] Filtrado el código de Whatsapp que bloquea a Telegram [ENG] […]

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