problem with if condition

agn has asked for the wisdom of the Perl Monks concerning the following question:

Hi,
Am writing a basic webserver where I need to check if a the requested URI has a slash at the end or not and respond appropriately according to the condition.

my $DOCROOT = '/home/agn/htdocs';

if (-e $DOCROOT.$uri) {
            if (-f $DOCROOT.$uri) {
                if (-r $DOCROOT.$uri) {
                    logme("200 HTTP OK\n");
                    $status_code = 200;
                } else {
                    logme("403 Forbidden\n");
                    $status_code = 403;
                }
            } elsif (-d $DOCROOT.$uri) {
                if (-r $DOCROOT.$uri
                        && -x $DOCROOT.$uri
                        && ($DOCROOT.$uri !~ /\/$/)) {
                    logme("301 Moved Permanently\n");
                    $status_code = 301;
                } elsif (-r $DOCROOT.$uri && -x $DOCROOT.$uri) {
                        logme("200 HTTP OK\n");
                        $status_code = 200;
                } else {
                    logme("403 Forbidden\n");
                    $status_code = 403;
                }
            } else {
                logme("406 Not Acceptable\n");
                $status_code = 406;
            }
        } else {
            logme("404 Not Found\n");
            $status_code = 404;
        }
    }
    return 0;
}
[download]

The problem is that whether the $DOCROOT.$uri contains a / at the end or not, it always sets $status_code to 301.
$DOCROOT.$uri !~ m/\/$/
The above condition isn't being checked. Or if it is, I have a bug in the RE. Any ideas ?

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Replies are listed 'Best First'.
Re: problem with if condition by Corion (Patriarch) on Jul 13, 2009 at 09:30 UTC
`.` binds less strong than `~=` does. Using double quotes or parentheses makes your code work. Change `&& ($DOCROOT.$uri !~ /\/$/)) {` [download] to `&& ("$DOCROOT$uri" !~ /\/$/)) {` [download] or, even better, construct a variable `$local_path` from `$DOCROOT` and `$uri`. Note that your webserver will allow access to directories outside of `$DOCROOT` if `$uri` contains for example `../../`.	[reply] [d/l] [select]
Re^2: problem with if condition by agn (Initiate) on Jul 13, 2009 at 09:53 UTC
Doh! I feel stupid for not knowing that. I should really read about the precedence rules. Thanks a bunch. I've really been frustrated with this. Also I didn't catch this while running it through the debugger (perl -d). About .. traversals, I sanitise $uri before passing it to the above snippet. -agn	[reply]
Re: problem with if condition by Bloodnok (Vicar) on Jul 13, 2009 at 12:01 UTC
TIMTOWTDI: If you're using Apache, IIRC, you can simplify things by doing the same thing (or similar) in `/etc/httpd.conf`. A user level that continues to overstate my experience :-))	[reply] [d/l]