Cgi Scripting problem

#!/usr/bin/perl -w

package path_ref;
require 5.002;
sub new {
    my $self = {};
        bless $self;
        return $self;
}
sub gopath {
        my ($self) = @_;
        my @ff;
        my $mainServer = $ENV{'SERVER_ADMIN'};
 $mainServer =~ s/root@/http:///o;
        my $server = "http://$ENV{'HTTP_HOST'}";
        my $ref = " / / / / / / ";
        if ($ENV{'HTTP_REFERER'}) {
                $ref = $ENV{'HTTP_REFERER'};
        }
        if      ($ENV{'SCRIPT_FILENAME'} =~ /printenv.cgi/) {  # do this for the INCLUDED shtml
                $ref = "$server$ENV{'DOCUMENT_URI'}";
        }
        @ff = split///, $ref;
        my $fil = pop(@ff);
        if (($ref =~ /$server/)||($ENV{'REQUEST_METHOD'} eq "PUT")){ # the form and cgi have same domain
                if ($mainServer eq $server) { # no new domain
                        @path = ($mainServer,"$ff[4]/$ff[5]", $server, $fil);
                } else { # new domain
                        @ff = split///, $ENV{'DOCUMENT_ROOT'};
                        @path = ($mainServer, "$ff[5]/$ff[6]", $server, $fil);
                }
        } else { # the form and cgi don't have same domain hacker
                @path = ("error");
        }
        return @path;
}
1;

[root@site modP]# perl printenv.cgi
Use of uninitialized value in substitution (s///) at path_ref.pm line 14.
Use of uninitialized value in concatenation (.) or string at path_ref.pm line 15.
Use of uninitialized value in pattern match (m//) at path_ref.pm line 20.
Use of uninitialized value in string eq at path_ref.pm line 25.
Content-type: text/html