PHP Script Uploads despite error

[oddball25]

Hey

I have a php upload script that i am using which works ok, when the criteria has not been met, it echo's back to the user the problem, however the file still uploads to the server anyway despite saying the conditions haven't been met. Can anyone shed some light on this?

<?php
//define a maxim size for the uploaded images in Kb
 define ("MAX_SIZE","7000");
 
 //define a minim size for the uploaded images in Kb
 define ("MIN_SIZE","100");

//This function reads the extension of the file. It is used to determine if the file  is an image by checking the extension.
 function getExtension($str) {
         $i = strrpos($str,".");
         if (!$i) { return ""; }
         $l = strlen($str) - $i;
         $ext = substr($str,$i+1,$l);
         return $ext;
 }

//This variable is used as a flag. The value is initialized with 0 (meaning no error  found) 
//and it will be changed to 1 if an errro occures. 
//If the error occures the file will not be uploaded.
 $errors=0;
//checks if the form has been submitted
 if(isset($_POST['Submit']))
 {
     //reads the name of the file the user submitted for uploading
     $image=$_FILES['image']['name'];
     //if it is not empty
     if ($image)
     {
     //get the original name of the file from the clients machine
         $filename = stripslashes($_FILES['image']['name']);
     //get the extension of the file in a lower case format
          $extension = getExtension($filename);
         $extension = strtolower($extension);
     //if it is not a known extension, we will suppose it is an error and will not  upload the file, 
    //otherwise we will do more tests
 if (($extension != "jpg") && ($extension != "jpeg") && ($extension != "tif"))
         {
        //print error message
             echo '<h1>Unknown extension!</h1>';
             $errors=1;
         }
         else
         {
//get the size of the image in bytes
 //$_FILES['image']['tmp_name'] is the temporary filename of the file
 //in which the uploaded file was stored on the server
 $size=filesize($_FILES['image']['tmp_name']);

//compare the size with the maxim size we defined and print error if bigger
if ($size > MAX_SIZE*1024)
{
    echo '<h1>You have exceeded the size limit!</h1>';
    $errors=1;
}

if ($size < MIN_SIZE*1024)
{
    echo '<h1>You have not met the minimum size limit!</h1>';
    $errors=1;
}

//we will give an unique name, for example the time in unix time format
$image_name=time().'.'.$extension;
//the new name will be containing the full path where will be stored (images folder)
$newname="images/".$image_name;
//we verify if the image has been uploaded, and print error instead
$copied = copy($_FILES['image']['tmp_name'], $newname);
if (!$copied)
{
    echo '<h1>Copy unsuccessfull!</h1>';
    $errors=1;
}}}}

//If no errors registred, print the success message
 if(isset($_POST['Submit']) && !$errors)
 {
     echo "<h1>File Uploaded Successfully!</h1>";
 }

 ?>

[is_numeric]

should this not be OR ( || ) instead of &&

if (($extension != "jpg") || ($extension != "jpeg") || ($extension != "tif"))