# SSL connect to server
    my $retry = 10;
    my $server = undef;
    while ($retry > 0) {
        $server = IO::Socket::SSL->new(
            PeerAddr    => $host,
            PeerPort    => "https",
        );
        if ($server && $server->connected()) {
            print "proxy $$ connected to server\n";
            last;
        } else {
            $retry--;
            warn "proxy $$ connect to server failed: $!,".IO::Socket::SSL::errstr();
            warn "proxy $$ ".($retry ? 'will retry' : 'giving up')."\n";
        }
    }