cgi-dev

commit 3ff9dbc26a9a04d19c2e2bf18d5ee22d836f17b2
parent 22d4e961b55e934d6f1b04e898cdb3c21d37e41a
Author: Samir Parikh <noreply@samirparikh.com>
Date:   Fri, 25 Feb 2022 22:01:50 +0000

get authentication error subroutine to work

Diffstat:
M
guess_number3.cgi
 | 
31
++++++++++++++++++++++++++++++-

1 file changed, 30 insertions(+), 1 deletion(-)
diff --git a/guess_number3.cgi b/guess_number3.cgi
@@ -4,15 +4,18 @@ use warnings;
 use strict;
 use CGI;
 use CGI::Cookie ();
+use MD5 ();
 
 use constant TRIES => 6;
-use constant COOKIE_NAME => 'guess_number_2';
+use constant COOKIE_NAME => 'guess_number_3';
+use constant SECRET => 'mySuperSecretSecret';
 my $game = CGI->new;
 
 # state maintenance subroutines
 sub get_state {
     my %state = $game->cookie( COOKIE_NAME );
     return undef unless %state;
+    authentication_error() unless cookie_check( \%state, 'check');
     return \%state;
 }
 
@@ -29,6 +32,7 @@ sub initialize {
 
 sub save_state {
     my $state = shift;
+    cookie_check( $state, 'generate' );
     return CGI::Cookie->new (
         -name           => COOKIE_NAME,
         -value          => $state,
@@ -171,6 +175,31 @@ sub print_footer {
     print $game->end_html();
 }
 
+# message authentication checks
+sub cookie_check {
+    my ($state, $action) = @_;
+    return unless ref( $state );
+    my @fields = @{$state}{qw(NUMBER GUESSES_LEFT GUESSED GAMENO WON)};
+    my $newmac = MD5->hexhash(
+        SECRET . MD5->hexhash( join '', SECRET, @fields )
+    );
+    return $state->{MAC} = $newmac if $action eq 'generate';
+    return $newmac eq $state->{MAC} if $action eq 'check';
+    return undef;
+}
+
+sub authentication_error {
+    my $cookie = CGI::Cookie->new(-name => COOKIE_NAME, -value=>'',-expires => '-1d');
+    print $game->header(-cookie => $cookie),
+          $game->start_html(-title => 'Authentication Error'),
+          $game->h1($game->font({-color => 'red'}, 'Authentication Error')),
+          $game->p('This application was unable to confirm the integrity of the',
+          'cookie that holds your current score.',
+          'Please reload the page to start a fresh session.'),
+          $game->p('If the problem persists, contact the webmaster.');
+    exit 0;
+}
+
 # begin main program
 # retrieve current state
 my $state = get_state() unless $game->param( 'clear' );