Redirect 301 for facebookexternalhit/1.1

Hi all,

I’m experiencing a strange behavior with Facebook (facebookexternalhit/1.1) using WP 3.2.1. It all started with the Facebook Comments plugin (the one by Alex Moss) which was returning a “unreachable page” error for every single URL on my blog.

I tried their debug tool (https://developers.facebook.com/tools/debug) to see what was happening exactly. In the end, it seemed that they were getting a permanent redirection (301) for all of my pages.

Taking a look a my Apache2 log, here’s what I see:

[12/Aug/2011:14:13:37 -0400] "GET / HTTP/1.0" 301 20 "-" "facebookexternalhit/1.1 (+https://www.facebook.com/externalhit_uatext.php)"

I tried to emulate exactly the same request, same user-agent (using cURL) to see what would happen… However, I don’t get a 301, even if the request is exactly the same:

[12/Aug/2011:14:14:06 -0400] "GET / HTTP/1.0" 206 20 "-" "facebookexternalhit/1.1 (+https://www.facebook.com/externalhit_uatext.php)"

In fact, only IP differs! When I try Facebook debug tool on a static url such as WordPress License (license.txt), Facebook is able to reach the page. I’ve done multiple tests, and in the end, I can confirm that for an unknown reason, Facebook gets constantly redirected when trying to access a page served by WordPress.

For now, what I did is I patched the wp_redirect function in wp-includes/pluggable.php:

At the beginning of function (Around line 922):


function wp_redirect($location, $status = 302) {

if ($_SERVER["HTTP_USER_AGENT"] == "facebookexternalhit/1.1 (+https://www.facebook.com/externalhit_uatext.php)") {
die();
}

global $is_IIS;

...

It does the trick, but it’s not really clean, so I wanted to know if someone else is experiencing this issue.

Can it be my theme?

I tried deactivating all of my extensions, but I was still running into this issue.

Thanks!