My site uses bookmarklets to gather data from external sites, kinda like Pinterest. I'm concerned about security and want to move the images the bookmarklet gathers from the doc root up one level. My script has some hefty security checks in place, but I want to add this as a last line of defense.
How do I access my images within my script? Obviously using ../userimages/id/image.jpg wont work. I'm using Apache.
Thanks!
Proxy the image
You would use a proxy script to feed the images through like the following example:
// open the file in a binary mode
$name = '../userimages/id/image.jpg';
$fp = fopen($name, 'rb');
// send the right headers
header("Content-Type: image/png");
header("Content-Length: " . filesize($name));
// you may like to set some cache headers here
// dump the picture and stop the script
fpassthru($fp);
exit;
This example is from the PHP manuals fpassthru() page. You would save this script somewhere in your servers document root/httpdocs folder.
"Spoofing" the URL to the image
The easiest way to give the PHP file the appearance of being an image file to a user/browser is to use Apaches mod_rewrite. Usually I use a URL structure something like this:
http://www.example.org/image-id/image.png
Where image-id is the unique identifier for that particular image. This way the file has the correct extensions of an image instead of .php.
Related
I am trying to read multiple image files from a folder (.htaccess protected) and display in a HTML page using php readfile().
The problem is I can see only the first image is read and the next is not shown in the browser. The code is as below
<?php
$image1 = 'files/com_download\256\50\www\res\icon\android\icon-36-ldpi.png';
$image2 = 'files/com_download\256\50\www\res\icon\android\icon-48-mdpi.png';
$imginfo = getimagesize($image1);
header("Content-type: ".$imginfo['mime']);
readfile($image1);
$imginfo = getimagesize($image2);
header("Content-type: ".$imginfo['mime']);
readfile($image2);
?>
I could see the first image 'icon-36-ldpi.png' successfully read and displayed in the browser and the second image is not read and not displayed in the browser.
Am I missing something? Any advice please.
Sorry if I am doing stupid but the requirement is to read multiple image files and render in the browser like a grid view. I cannot use img tag because of security reasons.
You can't dump both images out at once. Why not make two images in your html so the browser makes two calls to your script. Then use a GET param to pass the filename you want to display.
---Edit---
Important Security Note
There is an attack vector which you open up when doing soething like this. Someone could easily view your source html and change the parameter to get your image script to output any file they want. They could even use "../../" to go up directories and search for well known files that exist. e.g. "../../../wp_config.php". Now the attacker has your wordpress database credentials. The correct way to prevent against this is to always validate the input parameter properly. For example, only output if the file name ends with ".jpg"
I am using codeingiter and had a image directory in it. Due to space issue I have shifted the entire directory to new location on same server.
Earlier path was /var/www/html/site_folder/assets/images
New Location is /home/new_site/images
Now when I want to display images on web site its not getting load.
I have tried using the below code
$file = '/home/new_site/images/3.jpg';
header('Content-Type: image/jpeg');
echo "<img src='".readfile($file)."' &glt;";
I have approximately 50 images and I want to load them on my site.
This works on local but not on server. I am using Linux on local and Centos on server.
You are mixing things up. What you want to do is to return the content of the image file, but you return an HTML fragment.
There are multiple solutions you could try:
Create a symbolic link to the new image directory, most things could stay as they are. This migth or might not work depending on your web server configuration.
Change all the references to images from
src="image5.jpg"
to something
src="image.php?name=image5.jpg"
Then you need the script "image.php" which takes the name of the image as a query parameter and then returns the content:
<?php
// take care to make some clever checks here
// otherwise you introduce a security nightmare
$file = '/home/new_site/images/' . htmlspecialchars($_GET["name"]);
header('Content-Type: image/jpeg');
readfile($file);
?>
This seems like it should be simple. I have a set of files I have to store outside of the webroot and have an access script to call them. I also need to sometimes tell a PDF that must be called via this proxy script to open at a specific page. Releveant part of the script below:
header('Content-type: application/pdf');
header('Content-Length: ' . filesize($file));
header('Content-Disposition: attachment; filename="'.$file_name.'"');
readfile($file);
$file_name is just the basename() of the file, and $file is the path to the file, with #page=2, or #page=10, or whatever appended to it. If I remove the hashtag portion, the script works fine and the PDF opens with no errors. When the hashtag portion is there, all the programs tell me the PDF has been corrupted and can't be open.
I can't seem to find anything on here or Google as to what I need to do. Do I need to set an additional header to simulate the hash tag? Use exec() to call some command line code instead of using readfile()?
Any insight would be greatly appreciated.
You have to append the #page=2 (or whatever page you want to open) to the URL in the browser, not the filename in the proxy-script.
You currently try to open a file myFile.pdf#page=2 from the filesystem that does not exist as the filename is myFile.pdf
The feature to open a pdf-file on a specific page on the other hand is implemented in the browser or it's PDF-plugin. Therefore the information which page to open has to be given to the browser via the URL. So you should call your proxyscript like this: http://example.com/proxy.php?myFile.php#page=2
Update:
If you want to download the file and open it at a specific page every time the file is opened from the local file-system of the user, you will have to edit (or recreate) the PDF-File.
The following problem I can't really wrap my mind around, so really if you guys can't be bothered to supply the entire code some tips leading in the right direction would be great!
So, I have a script where users can upload images to a server. PHP takes care of validating the file and saving it using a new filename in another folder, neither known by the client. Now, the client should be able to see the uploaded image, in html simply:
style="background-image:url('testimagegif.gif');
But preferably the client should not be able to see the path nor the file name of the image saved on the server. I know about using header('Content-type: ... for forcing the client browser to download files, but I do not see how this, nor any similar solution could be applied to this case. Same goes for readfile. If I use it the browser simply downloads the image, not placing it in the html.
You should probably be moving the files into a publicly readable folder on your webserver if you want to serve them.
Otherwise, you'll need something like readfile()
There are two options for this, you could use the data protocol, which would embed the whole image into the URL of the background ( this isn't recommended if the image is bigger than a few kb. ) or you can use a script to present the image by encoding or recording a unique key for the image, eg bg.php?id=4323-34442-3432-4532 which checks a db for the id to retrieve the file path then echoes the content with the right content type.
Some examples;
based on the Data URI wikipedia page
Data URI Method
Assuming a function like this;
function data_uri($fileID) {
$fRecord = mysql_fetch_array(
mysql_select("SELECT filePath, mimeType from fileTable WHERE fileID = " $fileID . ";")
);
$contents = file_get_contents($fRecord['filePath']);
$base64 = base64_encode($contents);
return "data:$fRecord['mimeType'];base64,$base64";
}
Then in your html/php page you'd have the following snippet
style="background-image:url('<?php echo data_uri($fileID);?>'
PHP Image Dump
Assuming a function like this;
// Given a filename and a mimetype; dump the contents to the screen
function showDocumentContent($fileID){
$fRecord = mysql_fetch_array(
mysql_select("SELECT filePath, mimeType from fileTable WHERE fileID = " $fileID . ";")
);
header( 'Content-Encoding: none', true );
header( 'Content-Type: ' . $fRecord['mimeType'], true );
echo readfile( $fRecord['filePath'] );
}
Then in your html page you'd have this;
style="background-image:url('image.php?fileID=123')
In the first case, images larger than a few KB will result in equally large HTML pages, and may not be supported in browsers consistently. In the second case, you'd effectively have created a php script that is pretending to be an image. In both cases, the real path to the binary files on your server is abstracted away by storing a mapping in a database.
If you store the paths to the files somewhere like a database or a file, you can use readfile() to output the file once you retrieve the path.
Combine that with the content-type header, and set the background-image URL to the PHP script with the correct query string like so:
style="background-image:url('script.php?img=30382');"
You must expose some path to the client, because their browser has to access the file. You can use your webserver config to serve at an indirected location, or serve the image with PHP and have the real path in a call to readfile()
For an image file (JPEG) that has been uploaded to the server via a PHP script (to a directory such as http://www.somedomain.com/images, is it a good idea to allow the client to get the image's direct address (such as http://www.somedomain.com/images/someimage.jpg and paste it into a WYWSIWYG text editor (such as TinyMCE)?
I am wondering if there is a preferable method where the direct address is encrypted?
Please, if I should just link directly to the image, just say so.
Thanks!
Note: I have modified this question from my original. Please see revisions if you are curious, but I think I was asking the question incorrectly. My apologies to the people who already answered.
As long as you check correctly WHAT is being uploaded, it shouldn't be a problem. So please at least use getimagesize or a similar function to make sure it's an image that's being uploaded, AND make sure the extension on the file is correct so that it will never be run through the PHP interpreter - to prevent someone from uploading an image with a PHP script attached.
BTW Here's a nice whitepaper on uploads and security : http://www.scanit.be/uploads/php-file-upload.pdf
Depending on the CPU Constraints of your web-hosting service you can write a service to 'serve' the images to your users.
Here is some very BASIC code, it needs spiffing up and cleaning up for XSS/etc...
<?php
$basePath = "/path/to/my/image/store/not/web/accessible/";
$file = NULL;
if (isset($_GET['file']))
$file = $_GET['file'];
if ($file != NULL)
{
$path = $basePath . $file;
// $file needs to be checked for people
// trying to hack you, but for the sake of simplicity
// i've left it out
$mime = mime_content_type($path);
$size = filesize($path);
header("Content-Length: " . $size);
header("Content-Type: " . $mime);
header('Expires: 0');
readfile($path); // Outputs the file to the output buffer
}
?>
Obviously you can put whatever security checks in here you want. But this way your files are below the web dir, and you can apply logic to thier accesibility. This is typically used more for FILE vs. Images, but you can do the same thing here.
Images Accessed like this
http://www.mysite.com/image.php?file=hello.jpg
And you can use mod_rewrite to rewrite urls like this:
`http://www.mysite.com/images/hello.jpg
Into the first url.
I Cannot stress enough the need for further security checking in the above example, it was intended to show you how to serve a file to the user using PHP. Please don't copy & use this verbatim.
Wordpress uses direct links for images. The permalink function simply puts the image on a page along with metadata for comments, but the images' SRC attributes still link directly to the image.
why are you concerned about revealing your image location. Hotlinking?
if so you can prevent hotlinking with htaccess
http://altlab.com/htaccess_tutorial.html
Didn't you get your answer already?
Every site reveals image location to the browser. It's just the way web works.
Got any reason to "encrypt" original location?