Auto Download

Call this function, and the server will send the user a request to begin downloading a file instead of sending it through the browser (e.g. if you called the function on a PHP file, the server would allow the user to download the source code of that file instead of serving it) Of course, that's why this code contains exceptions that don't allow you to download certain files to prevent that type of thing from happening. To use, simply call the function dl_file(filename) with the filename.

	function dl_file($file){
	
	   //First, see if the file exists
	   if (!is_file($file)) { die("<h2>404 File not found!</h2>"); }
	
	   //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": $ctype="application/zip"; break;
		 case "doc": $ctype="application/msword"; break;
		 case "xls": $ctype="application/vnd.ms-excel"; break;
		 case "ppt": $ctype="application/vnd.ms-powerpoint"; break;
		 case "gif": $ctype="image/gif"; break;
		 case "png": $ctype="image/png"; break;
		 case "jpeg":
		 case "jpg": $ctype="image/jpg"; break;
		 case "mp3": $ctype="audio/mpeg"; break;
		 case "wav": $ctype="audio/x-wav"; break;
		 case "mpeg":
		 case "mpg":
		 case "mpe": $ctype="video/mpeg"; break;
		 case "mov": $ctype="video/quicktime"; break;
		 case "avi": $ctype="video/x-msvideo"; break;
	
		 //The following are for extensions that shouldn't be downloaded (sensitive stuff, like php files)
		 case "php":
		 case "htm":
		 case "html":
		 case "txt": die("<b>Cannot be used for ". $file_extension ." files!</b>"); break;
	
		 default: $ctype="application/force-download";
	   }
	
	   //Begin writing headers
	   header("Pragma: public");
	   header("Expires: 0");
	   header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
	   header("Cache-Control: public");
	   header("Content-Description: File Transfer");
	  
	   //Use the switch-generated Content-Type
	   header("Content-Type: $ctype");
	
	   //Force the download
	   $header="Content-Disposition: attachment; filename=".$filename.";";
	   header($header );
	   header("Content-Transfer-Encoding: binary");
	   header("Content-Length: ".$len);
	   @readfile($file);
	   exit;
	}