Graphics

Remote image checker

Type:	code fragment
Added by:	robF
Entered:	16/06/2003
Last modified:	06/12/2002
Rating:	- (fewer than 3 votes)
Views:	4200

If you have a message board which allows people to post inline images with the IMG tag, you can use this function to run a few checks on the remote image. Simply pass it the URI to the image, and it checks the file exits; that it is a recognised image format; and that it is smaller than a predeterminted size. This stops mischief-makers linkng your page to a 4TB file.

<?php
function validate_image($l, $maxsize = 20000) {

                            

                                // Check for the existance and hopefully the size and type of that

                                // image. We'll return an HTML string if successful, and an integer if

                                // not. Returns true if the image is okay, false if not

                            

                                $ret = true;

                            

                                if (!$ih = @fopen($l, "r"))

                                    $ret = false;

                            

                                // Looks like the image exists. If we've got the mighty cURL, we can do

                                // a bit more checking

                            

                                if (function_exists("curl_init")):

                                    $c = curl_init();

                                    curl_setopt($c, CURLOPT_URL, $l);

                                    curl_setopt ($c, CURLOPT_NOBODY, TRUE);

                                    curl_exec($c);

                                    $size = curl_getinfo($c, CURLINFO_CONTENT_LENGTH_DOWNLOAD);

                                    $type = curl_getinfo($c, CURLINFO_CONTENT_TYPE);

                                    curl_close($c);

                            

                                    if ($size > $maxsize || !ereg("^image/", $type))

                                        $ret = false;

                            

                                endif;

                            

                                return $ret;

                            }
?>

Usage Example

See the example

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