Check where request came from

Question

on the site when an image is required the link is like this

<img src="getimage.php?id=<?php echo $name ?>" " width="280px" height="70px">

Then on getimage.php it gets the id and from that finds the right picture and displays it.

$id = $_GET['id'];

This works perfectly. How would I find out where the request came from. So on which page this line below was on

<img src="getimage.php?id=<?php echo $name ?>" "width="280px" height="70px">

So ultimately I can know if the image requested is for index.php or about.php etc

Thanks

Answer 1

You can add an additional parameter to the image URL that specifies from which page it was requested:

<img src="getimage.php?id=<?php echo urlencode($name); ?>&page=<?php echo urlencode($page); ?>" "width="280px" height="70px">

Works exactly like how you did it with the id parameter.

The benefit is, this does not rely on some headers browsers send (or not) like the HTTP Referer, something you have no control over from server-side.

To obtain the page the image-link is generated on, you can use something like this:

$page = basename(__FILE__);

See basename ^{PHP Manual} and __FILE__ ^{PHP Manual}.

Additionally, the code makes use of the urlencode ^{PHP Manual} function to ensure that the attribute doesn't break.

Answer 2

If set, look for the key HTTP_REFERER in the $_SERVER array:

$_SERVER['HTTP_REFERER'];

The address of the page (if any) which referred the user agent to the current page. This is set by the user agent. Not all user agents will set this, and some provide the ability to modify HTTP_REFERER as a feature. In short, it cannot really be trusted. (source)