game.cgi

#!/usr/bin/perl -w

use CGI qw/:all/;
use CGI::Carp qw/fatalsToBrowser warningsToBrowser/;
$max_number_to_guess = 99;
sub main() {
    # print start of HTML ASAP to assist debugging if there is an error in the script
    print page_header();

    # Now tell CGI::Carp to embed any warning in HTML
    warningsToBrowser(1);

	$username = param('username') || '';
	$password = param('password') || '';


	# remove any non-word characters from username
	# another malicious user could include ../ in username
	$username =~ s/\W//g;
	# limit username to 32 word characters
	$username = substr $username, 0, 32;


	if (!$username || !$password) {
      print login_form();
   } elsif (open F, "accounts/$username/password") {
      $check = <F>;
      chomp $check;
      if ($password eq $check) {
	      $guess = param('guess') || '';
	      # remove any non-digit characters from guess
	      $guess =~ s/\D//g;

	      $number_to_guess = param('number_to_guess') || '';
	      $number_to_guess =~ s/\D//g;

         if (-e "accounts/$username/number") {
            ;
         } else {
            open G, ">", "accounts/$username/number";
            close G;

         }

         if (open G, "<", "accounts/$username/number") {
            $number_to_guess = <G>;
            close G;
            if($number_to_guess eq ""){
               $number_to_guess = 1 + int(rand $max_number_to_guess);
               open H, ">", "accounts/$username/number";
               print H "$number_to_guess";
            }
         }

         if ($guess eq '') {
            print "I've thought of a number.\n";
	         print guess_number_form($username, $password);
         } elsif ($guess eq $number_to_guess) {
       		print "You guessed right, it was $number_to_guess.\n";
            # delete number file here
            if (-e "accounts/$username/number") {
               unlink('accounts/$username/number');
            }
            unlink "accounts/$username/number";
       		print new_game_form($username, $password);
         } elsif ($guess < $number_to_guess) {
       		print "Its higher than $guess.\n";
	         print guess_number_form($username, $password);
         } else {
       		print "Its lower than $guess.\n";
	         print guess_number_form($username, $password);
         }
      } else {
	      print "Incorrect password!\n";
      }
   } else {
      print "Unknown username!\n";
   }

    print page_trailer();
}

# form to allow user to supply username/password

sub login_form {
	return <<eof;
    <form method="POST" action="">
        Username: <input type="textfield" name="username">
        <p>
        Password: <input type="password" name="password">
         <p>
        <input type="submit" value="Login">
    </form>
eof
}

#
# form to allow user to guess a number
#
# Pass username & password to next invocation as hidden
# field so user doesn't have to login again
#

sub guess_number_form {
	my ($username, $password) = @_;
	return <<eof;
    <form method="POST" action="">
    	Enter a guess between 1 and $max_number_to_guess (inclusive):
     	<input type="textfield" name="guess">
     	<input type="hidden" name="username" value="$username">
     	<input type="hidden" name="password" value="$password">
     </form>
eof
}

#
# form to allow user to go to a new game
#
sub new_game_form {
	my ($username, $password) = @_;
	return <<eof;
    <form method="POST" action="">
        <input type="submit" value="Play Again">
     	<input type="hidden" name="username" value="$username">
     	<input type="hidden" name="password" value="$password">
    </form>
eof
}


#
# HTML placed at the top of every page
#
sub page_header {
    return <<eof
Content-Type: text/html;charset=utf-8

<!DOCTYPE html>
<html lang="en">
<head>
<title>Guess A Number</title>
</head>
<body>
eof
}


#
# HTML placed at the bottom of every page
#
sub page_trailer {
    return "</body>\n</html>\n";
}

main();
exit(0);