sub socketstart($self, $ua) {

    my $sysh = $self->{server}->{modules}->{$self->{systemsettings}};

    my $upgrade = $ua->{headers}->{"Upgrade"};
    my $seckey = $ua->{headers}->{"Sec-WebSocket-Key"};
    my $protocol = $ua->{headers}->{"Sec-WebSocket-Protocol"};
    my $version = $ua->{headers}->{"Sec-WebSocket-Version"};

    if(!defined($upgrade) || !defined($seckey) || !defined($version)) {
        return (status => 400); # BAAAD Request! Sit! Stay!
    }

...

    $seckey .= "258EAFA5-E914-47DA-95CA-C5AB0DC85B11"; # RFC6455 GUID for Websockets

    $seckey = encode_base64(sha1($seckey), '');

    my $proto = 'base64';
    if($settings{binaryMode}) {
        $proto = 'binary';
    }
    
...

    my %result = (status      =>  101,
                  Upgrade     => "websocket",
                  Connection  => "Upgrade",
                  "Sec-WebSocket-Accept"  => $seckey,
                  "Sec-WebSocket-Protocol" => $proto,
                 );

    return %result;
}