Codeigniter instance and external library object: authentification - codeigniter

Question

I will try to be as clear as possible to explain my problem. If not, tell me !
Mywebapp is based on Codeigniter. In it, I did a controller in order to show images uploaded by the users. By this way, the images can only be seen by members or authorized people and are not public like in facebook for example (image addresses are just hashed but are public).
I also use the mpdf library to generate a pdf from the content of a web page. To use it, I have in the third party directory the mpdf library. To be able to use it with my formatting, I put in the library directory (in application directory) my mpdf library (just to be able to use it from different controller). I have a pdf controller which is called from the view where I want to generate the pdf.
So the process is : I call a function of the pdf controller from my view. In this function, I call a function of my mpdf library which create a mpdf object (the third party class) and generate the pdf.
The generation of the pdf works great. The only I had is for the images. I explain. In my html document, the image are embedded like that :
<img src="http:localhost/www/myapp/library/image/hashed_name_of_the_image" alt="" />
The image function of the library controller retrieve the image and shows it. But in this function, I can protect or not the access to run it. For example, to force to be a logged user to see an image (if($this->session->userdata(‘logged’) == true)).
If there is no restriction, the generated pdf contains the images. Cool :).
But if I put a restriction, it doesn't. I understand that the mpdf object is the one which is asking to image function to show the image. So the verification failed.
I tried to use a config parameter on the CI instance object before I call the pdf function. For example, set to true a "pdf_conversion" and the conversion finished, set it back to false.
But it doesn't work. When I check the value in the image function, it's still false... It's like the config value is not change for all object but only for th pdf object which has changed it.
Is there a way to do what I want to do ??? With config parameter or anything else !!! I think I misunderstood something but don't know what !
thanks by advance for answers
Bastien

Answer 1

You problem is that then the library "calls" the image function, it is not logged in. So your controller code denies access.
There are two things you can do:
Move the code that generates/gets the image form the controller into a new library. then call that library from the controller and from the PDF library. This is the preferred way.
In the "image" action, find a way to check if the request is coming from the PDF library. Best guess is to look for something in the HTTP headers the PDF library sends. Anyway this is not very secure since HTTP headers can be "faked".
OFF TOPIC: Is there a reason you server the image from a controller action instead of by directly referencing the image file?
CLARIFICATION ON SOLUTION 1
So you'll have a library image.php that looks like this
class Image {
...
function get_image($hash){
[code for getting the image here]
}
...
}
In the controller:
function image($hash) {
$this->load->library('image');
if (if($this->session->userdata(‘logged’) == true)) {
$image = $this->image->get_image($hash);
[send it to the browser]
}
}
In the PDF library
function export($hash) {
$ci =& get_instace();
$ci->load->library('image');
[do pdf stuff]
$image = $ci->image->get_image($hash);
$this->add_image($image);
[do more pdf stuff]
}
This is the idea, the actual details of the implementation are up to you.