PHP: Adjusting Output Based on HTTP Referrer

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PHP: Adjusting Output Based on HTTP Referrer
Filed under Tutorials, Web development.

PHP There might be many cases where different output would want to be displayed differently depending on where someone is accessing a web page from.

A HTTP referer “identifies, from the point of view of an internet webpage or resource, the address of the webpage, of the resource which links to it”.

Below is a simple way to change the output of your web page based on HTTP referrer:

PHP [Show Styled Code]:

$referrer = $_SERVER['HTTP_REFERER'];
if (preg_match("/hackosis.com/",$referrer)) {
      echo "Your referrer is correct.";
} else {
      header('Location: http://www.hackosis.com/');
};

PHP [Show Plain Code]:

$referrer = $_SERVER[‘HTTP_REFERER’];
if (preg_match("/hackosis.com/",$referrer)) {
      echo "Your referrer is correct.";
} else {
      header(‘Location: http://www.hackosis.com/’);
}; 

What the above code will do is redirect anyone that doesn’t have a referrer that has ‘hackosis.com’ somewhere in the URL to your homepage. You could also state a message such as “Hotlinking images is not allowed”. In this case it would be appropriate to display the image in the first part of the if statement.

I hope you find this helpful and if you need any other tips on PHP code snippets, please let us know in the comments.