#!/usr/bin/perl
use strict;
use warnings;
use CGI;

our $q = CGI->new();
our @cookie_jar=();
our $secure_cookie = defined $q->cookie('securecookie')
                     ? $q->cookie('securecookie')
                     : '';

# is a valid cookie set?
if ($secure_cookie) {
    if ( cookie_ok($secure_cookie) ) {
         show_secure_stuff();
    }
    else {
        # invalid cookie, so delete and show form
        push @cookie_jar, $q->cookie( securecookie => '' )
        show_form();
    }
}

# have they just completed the form
elsif ($q->param('username')) {
    check_login_combo();
}

# first run, so show form
else {
    show_form();
}

sub show_form {
    # display login form here
    # with fields 'username' and 'password'
}

sub check_login_combo {
    # based on username, grab correct crypted password
    # from db/textfile and store in $stored_cryptpass
    # do various other error checks and re-present form
    # if invalid input
    
    my $user = $q->param('username');
    my $pass = $q->param('password');
    if ($stored_cryptpass eq crypt($pass,$stored_cryptpass) {
        push @cookie_jar,
            $q->cookie({-name=>'secure_cookie',
                        -value=>"$user:$stored_cryptpass"});
        show_secure_stuff();
    }
    else {
        # bad login
        show_form();
    }
}

sub cookie_ok {
    # do similar check on cookie
    my ($user,$cryptpass) = split ':', $_[0];

    # grab stored_cryptpass and check
    return $cryptpass eq $stored_cryptpass
           ? 1 : 0;
}

sub show_secure_stuff {
    # display secure page here - ensuring you send the cookie
    print $q->header(-cookie => \@cookie_jar).
          'rest of page here';
}
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