PHP uses REFERER root access to address for page jump_PHP tutorial

For example, I developed a Yellow Pages source code and transferred it to Script Home. I previously set a demo program address: http://www.jb51.net. But now this domain name needs to be used for other sites, and what should I do if the original demo address becomes invalid? Then I can use PHP REFERER to determine the source. If it comes from the address of the webmaster's download station, I will transfer it to the site domain name.

I placed the following code in index.php on the site http://www.jb51.net to allow access from files.jb51.net to locate my server’s commonly used software download http:/ /s.jb51.net

You can go to the demo address on this page