my %file_ok = qw{
    	.gif	1
    	.jpg	1
    	.htm	1
    	.html	1
    	.txt	1
    	.doc	1
    	.pdf	1
    };

and then....

    ($base,$path,$type) = fileparse($file,'\..*');


and finally...

    $type =~ tr/A-Z/a-z/;
    if (!$file_ok{$type}) {
    	print "The type of file you tried to upload ($type) is not supported.";
    	return;
    }