PHP inside img src - php

Question

Trying to see what actions can be performed with a PHP script that is being called via an image src like so:
<img src="http://example.com/script.php" />
Now, I have tried to include the PHP header() function in script.php:
<?php
header("Location: http://example.com");
I have also tried to echo an image url expecting the img to display it, which it didn't:
<?php
echo 'http://example.com/image.png';
Are there any ways of doing such things with a PHP script that is being called in the img src attribute?

Answer 1

Are there any ways of doing such things with a PHP script that is being called in the img src attribute?
No. A resource that is used as a src for an img tag needs to output image data, nothing else.
There are some exceptions, eg. a header("location: ....") redirect, but the redirect needs to point to another valid image resource, not a web site as you show in your example.

Answer 2

Check out the readfile() as a way to output your image file from your script.php
readfile($file);
Read more about it here in the manual:
http://php.net/manual/en/function.readfile.php
where Example #1 gives an idea of how to set up the headers.
The manual also states that:
readfile() will not present any memory issues, even when sending large
files, on its own.
and
A URL can be used as a filename with this function
ps: This was the way Wordpress Multisite used to open user uploaded (e.g. images) files.

Answer 3

Your script.php should return the output of an image with the correct headers. For instance:
<img src="/html/img/script.php" />
// Script.php
$file = "tiger.jpeg";
$type = "image/jpeg";
header("Content-Type: $type");
header("Content-Length: " . filesize($file));
readfile($file);

Answer 4

You should keep in mind that the src tag should directly point to an image file. However, it is possible to use PHP to create an image, for exmaple by using the GD library:
http://php.net/manual/en/book.image.php
So using:
<img src="http://example.com/script.php" />
is possible, as long as script.php really outputs an image file, for example by using the example as described here:
http://www.php.net/manual/en/image.examples-png.php
I used this kind of processing in the past to overlay texts on JPG images for a broker website (e.g. new, sold, for rent, etc.).

Answer 5

Are there any ways of doing such things with a PHP script that is being called in the img src attribute?
Yes, but the PHP Script has to output image data only, as stated in various other answers.
With that being said, just read the image and output it to the stream with readfile
header('Content-Type: image/png');
readfile($file);
exit();
I know I might be a couple years late to really help you, but the accepted answer just isn't true (anymore).