PHP: Image Check Extension

I am currently having some problems with my upload script. It does not check if the filetype is allowed or not, and i can't figure out why. Does anyone see my problem?

                //Reads the image name
            $image=$_FILES['image']['name'];

            //If empty
            if ($image == "") {
            echo '<div class="box_square form_error" style="margin-bottom:15px; padding:10px; font-size:11px;">Velg et bilde!</div>';
            $errors = 1;
            }   

            //If not empty
            if ($image)
            {
                //Get orgiginal name from client machine
                $filename = stripslashes($_FILES['image']['name']);
                //Get the extension
                $extension = getExtension($filename);
           开发者_开发问答     $extension = strtolower($extension);

                //If file extension not known, error. If not, continue
                if (($extension != "jpg") && ($extension != "jpeg"))
                {
                    //Error message
                    echo '<div class="box_square form_error" style="margin-bottom:15px; padding:10px; font-size:11px;">Bare JPG og JPEG er tilatte filtyper!</div>';
                    $errors = 1;

                }

It looks like an incorrect getExtension($filename). However, i don't know why you are using stripslashes.

How about

echo "the extension used is ".$extension."<br>";

after

$extension = strtolower($extension);

btw, you can extract the extension using expression regular

preg_match("/\.([^\.]+)$/", $filename, $extension);   

Do NOT rely on the extension but on the mime type instead.

You're counting on the user uploading a file with the proper extension. An alternative is getimagesize() it will also tell you the Mime type. http://us3.php.net/manual/en/function.getimagesize.php

list ( $width, $height, $type, $html_dim ) = getimagesize ($_FILES['image']['tmp_name']);
echo "\$type:" . var_dump($type);

I also see exif-imagetype() says it will do that too (but I've never used it). http://us3.php.net/manual/en/function.exif-imagetype.php