Upload with base64

gistfile1.php

<?php

function saveImage($base64img){
    
    if($base64img == ""){
        return "0";
    }else{
        define('UPLOAD_DIR', 'upload/');
        $base64img = str_replace('data:image/jpeg;base64,', '', $base64img);
        $data = base64_decode($base64img);
        $file = UPLOAD_DIR . makeRandomString(8).'.jpg';
        if(file_put_contents($file, $data)){
           return 'http://'.$_SERVER['SERVER_NAME'].'/'.$file;
        }else{
            return "0";
        }
    }
}

function makeRandomString($max=6) {
    $i = 0; //Reset the counter.
    $possible_keys = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
    $keys_length = strlen($possible_keys);
    $str = ""; //Let's declare the string, to add later.
    while($i<$max) {
        $rand = mt_rand(1,$keys_length-1);
        $str.= $possible_keys[$rand];
        $i++;
    }
    return $str;
}
//echo saveImage($_POST['file']);

print_r($_FILES);
$new_image_name = makeRandomString();
move_uploaded_file($_FILES["file"]["tmp_name"], "upload/".$new_image_name.".jpg");
?>