PHP Image content type problem - php

Question

I have a specific problem, and cant get over it.
For my latest project I need a simple PHP script that display an image according to its ID sent through URL. Here's the code:
header("Content-type: image/jpeg");
$img = $_GET["img"];
echo file_get_contents("http://www.somesite.hr/images/$img");
The problem is that the image doesn't show although the browser recognizes it (i can see it in the page title), instead I get the image URL printed out.
It doesn't work neither on a server with remote access allowed nor with one without.
Also, nothing is printed or echoed before the header.
I wonder if it is a content type error, or something else.
Thanks in advance.

Answer 1

Possibly the image doesn't fit into memory. Or your PHP installation doesn't have permissions to make external HTTP calls. Anyway, I suggest you never use echo file_get_contents(), use readfile instead.
Also you should never use raw strings from $_GET or $_POST for file operations. Always strip null-bytes, slashes and double dots from user-provided filenames, or better yet, allow only alphanumeric characters.

Answer 2

I was doing something like this recently, but found this a slow method (I was doing 15+ on a page). This is slow because first your server has to download the image, and then send it to the client. This means for every image it is downloaded twice.
I came up with an alternative - redirection. This allowed the client machines to directly access the other site while hiding the real url in the HTML source code.
$r - is processed above the script, and validated to make sure it is ok.
$webFile = 'http://www.somesite.com/'.$r['type'].'/'.$r['productid'].'.jpg';
header('Location: '.$webFile);
exit();
Granted if someone put my image url in the address bar, it would redirect and the user would see the real url, but it made my page faster and I wasn't too worried about that.

Answer 3

You'll want to ensure that your script is not outputting any white-space. Check before and after the opening/closing PHP tags.
If that checks out, you'll want to ensure that allow_url_fopen is set to On in php.ini

Answer 4

try embedding your php file that retrieves the image as <img> in your html
getImage.php
header("Content-type: image/jpeg");
$img = $_GET["img"];
echo file_get_contents("http://www.somesite.hr/images/$img");
in your html file
<img src="getImage.php?img=IMAGEID">

Answer 5

Probably you get some errors and the image is not displayed. Try to turn off the errors like this first:
ini_set('error_reporting', E_ALL);
ini_set('display_errors', 'Off');

Answer 6

Check that the variable exists in the query string, and use a regular expression to make sure that it doesn't contain anything other than alphanumeric characters or a period. Then use readfile() to stream the output to the browser.
// make sure the variable exists
if (isset($_GET['image'])) {
$image = $_GET['image'];
// make sure it contains only letters, numbers, the underscore, and a period
if (preg_match('/^[\w.]+$/', $image)) {
$file = "http://www.example.com/images/$image";
// send the correct header
header('Content-type: image/jpeg');
// stream the output
readfile($file);
}
}