Perl CGI redirect after cancelling on a 401 - perl

Question

I've currently got a small script running that sends a 401 to the client, upon cancelling and not providing user details the script will return nothing.
I'd like to send a redirect to the page they have come from instead.
The main subroutine looks like this;
#!usr/bin/perl
use strict;
use CGI;
sub checkAuth {
my ($user, $pass) = &getAuthUsers(); # Get the user and pass of already authenticated users.
unless ($user) {
&sendAuthenticationHeader(); # Send 401
}
# Check user against DB and return 1 for success.
if ( &checkUser($user, $pass) eq 'Y') { return 1 };
else { # This is the redirect I'm trying to issue.
my $cgi = CGI->new();
print $cgi->redirect($ENV{HTTP_REFERER}); # Redirect to the referer url
exit;
}
}
Unfortunately whenever I try to send new headers it's just received as plain text.
Any help is appreciated, thanks in advance.

Answer 1

sendAuthenticationHeader() emits a header with a 401 status code.
print $cgi->redirect($ENV{HTTP_REFERER}); emits a header with a 302 status code. Of course, since you've already emitted a header, this gets treated as the body.
There's no point to return a 401 if you want to redirect. Change your code to
sub checkAuth {
my ($user, $pass) = getAuthUsers();
if (!$user || !checkUser($user, $pass)) {
print CGI::redirect($ENV{HTTP_REFERER});
exit;
}
}
Notes:
Removed incorrect &. Don't tell Perl to ignore the prototype of subs. Address the underlying issue instead if required.
The return value of checkUser is boolean, so it should return either a true or a false value (e.g. 0 or 1), not two true values (e.g. N or Y). The above code assumed you fixed this.