<?php function dl_file($file){ //First, see if the file exists if (!is_file($file)) { die("<b>404 File not found!</b>"); } //Gather relevent info about file $len = filesize($file); $filename = basename($file); $file_extension = strtolower(substr(strrchr($filename,"."),1)); //This will set the Content-Type to the appropriate setting for the file switch( $file_extension ) { case "pdf": $ctype="application/pdf"; break; case "exe": $ctype="application/octet-stream"; break; case "zip":...