#!/usr/bin/perl -w

# simple echo server

use strict;
use Encode qw/ decode /;
use CGI;

binmode STDOUT, ":utf8"; # handle Unicode output

sub noHTML {
	my ($string) = @_;
	$string =~ s/&/\&/g; # remove tags and Unicode entities
	$string =~ s/</\&lt;/g; # to prevent insertion attack
	$string =~ s/>/\&gt;/g; 
	return $string;
} # noHTML

my $input = decode('UTF-8', CGI::param('parameter1') // 'no input');
$input = noHTML($input); # untaint to prevent XSS
# HTML header
print "Content-Type: text/html; charset=utf-8\n";
print "\n"; # separator before content
# HTTP content
print "<!DOCTYPE html>
	<html lang='en'><head>
	<title>Echo result</title>
	</head><body>
	<h1>You typed in <span style='color:red;'>$input</span>.</h1>
	</body></html>
";