为什么我不能摆脱Facebook用户代理？

Question

I'd like to use some permalink slug that allow the users to share the link (url.com/artist/songtitle) with it's Facebook pictures, url, description, and so on (Which is redirect the users to url.com/#/artist/songtitle). So i decided to showing the OG meta to Facebook user-agent and separate it from the redirector.

But, the problem come when i use the Facebook Debug Tools and try to fetch it . The crawlers wasn't caught by my user-agent separator.

Im using, this code to detect Facebook crawlers. Any idea to fix this problem?

strpos($_SERVER["HTTP_USER_AGENT"], "facebookexternalhit/") || strpos($_SERVER["HTTP_USER_AGENT"], "Facebot"

Answer 1

You may want to use stristr or a regex instead of strpos . As it is right now, your code won't match FacebookExternalHit , because it contains Capital Letters and strpos function is CaseSenSiTive .

---

Facebook User-Agents are:

 FacebookExternalHit/1.0 FacebookExternalHit/1.1 facebookexternalhit/1.0 (+http://www.facebook.com/externalhit_uatext.php) facebookexternalhit/1.1 (+http://www.facebook.com/externalhit_uatext.php) facebookexternalhit/1.0 (+https://www.facebook.com/externalhit_uatext.php) facebookexternalhit/1.1 (+https://www.facebook.com/externalhit_uatext.php) 

I'm using the code below to detect FB User-Agent in PHP and it works as intended:

$agent = $_SERVER['HTTP_USER_AGENT'];
if(stristr($agent, 'FacebookExternalHit')){
    //Facebook User-Agent
}else{
    //Other User-Agent
}

---

Update:

In order to know which user agents FB is using, try saving the user agent requests to a file, ie:

Example code to save UA requests:
Create a file named ua_log.txt with write permissions .

<?php
$agent = $_SERVER['HTTP_USER_AGENT'];
file_put_contents("$agent\n", "ua_log.txt", FILE_APPEND);    

Use the FB user agents on ua_log.txt to create your filter.

Answer 2

Figure it out. Be careful when you're writing og:url meta, the crawlers would like to follow it. So, make sure the page you're write in og:url is correct.