Let's explain this issue. It will be a little long, so thanks for your patience.
Background:
There is a framework named Mediawiki, which is used by Wikipedia. And there is a 3rd-party extension named Facebook login, which claims that I can allow people login to a Mediawiki website via Facebook account.
Problem:
Both of them are written in PHP.
My Mediawiki website environment is
+---------------+-----------+
| Product | Version |
+---------------+-----------+
| MediaWiki | 1.20.6 |
| PHP | 5.4.9 |
| MySQL | 5.5.31 |
+---------------+-----------+
And for the Facebook login extension, I get the latest version from github github.com/garbear/facebook-mediawiki
It doesn't work in Chrome, but works well in Firefox.
My DEBUG story:
First of all, the official Github repo misses a file named ExternalUser.php, I copy it from [path_to_mediawiki]/include and place it into this extension.
http://d.pr/f/F0MC this link is my working version. It only works as claimed in Firefox, but it doesn't work in Chrome
Why I ask facebook->getUser() return 0:
I tracked the whole extension by printing out some error log to check the value of variable.
The only difference between Chrome and Firefox is:
When I tested it on Google Chrome, after I typed my Facebook's username and password in the pop-up window, clicked the 'login' button. When I refreshed the Facebook website, it already showed as 'already login' status. But, in my mediawiki website, the page kept automatically refreshing in the login page, and can not redirect to 'already login' status and page.
So, I guess that maybe there's something wrong with the session/ cookies setting in Chrome. I checked my Chrome setting, and everything is default. I uninstalled Chome and re-installed it, yet I still have the same issue.
My next step is (has to be) to debug this extension. After spending a whole 2 days debugging this extension, I assume I found the exact code which is related with this issue.
In FacebookInit.php line 46
$facebook = new FacebookAPI();
To debug, let's modify it to
$facebook = new FacebookAPI();
error_log("==log===> ".$facebook->getUser(),0);
The additional statement will write variable $facebook->getUser() to apache error.log
When I try this on Firefox, it will return a positive integer, as 4 for Mark Zuckerberg, 12345678 for some other people. But when I try this on Chrome, it will always return 0.
I have tried most of the solutions on Stack OverFlow:
- Facebook PHP SDK works in Firefox but not in Chrome It is unsolved, and the OP used JavaScript instead of PHP
- getUser() returns 0 The suggestion is to download a new version of the Facebook PHP SDK. I did, but this did not fix my issue in Chrome.
- Facebook API : getUser() always returning 0 This tells me to include Facebook.php. Of course, the original code has already included it.
- Facebook application not run properly in IE Set a request HEAD. While this may can fix an issue in IE, it does not fix my issue in Chrome
- Facebook Connect - after login popup hangs in infinite loop Set variable cookies as true. It doesn't work.
If anyone has any idea what more I could try, I would appreciate the input.
If you have something like Avast Online Security (Version 9.0.2002.45) Extension in Chrome, just disable it and then refresh the page.
It would appear that avast is blocking the facebook JavaScript code (no clue why).