Troubleshooting: Asmack stream error (host-unknown)

Problem

When trying to write an Android demo with asmack, an error named 'host-unknown' appears. Here is the error seen in LogCat:

03-16 08:31:10.671: I/getConnection(795): connect success
03-16 08:31:10.905: W/System.err(795): stream:error (host-unknown)
03-16 08:31:10.905: W/System.err(795):    at org.jivesoftware.smack.PacketReader.parsePackets(PacketReader.java:261)
03-16 08:31:10.912: W/System.err(795):    at org.jivesoftware.smack.PacketReader.access$000(PacketReader.java:44)
03-16 08:31:10.912: W/System.err(795):    at org.jivesoftware.smack.PacketReader$1.run(PacketReader.java:71)

Below is the code used:

private static String host = "172.16.131.99";
private static int port = 5222;

private Button btnLogin;

private static XMPPConnection connection = null;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    btnLogin = (Button) findViewById(R.id.btnLogin);
    btnLogin.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {
            if (login()) {
                showMessage("Login success");
            } else {
                showMessage("Login failure");
            }
        }

    });
}

private XMPPConnection getConnection() {
    if (connection == null) {
        ConnectionConfiguration config = new ConnectionConfiguration(host, port, "");
        // use TLS
        config.setSecurityMode(SecurityMode.required);
        try {
            connection.connect();
            Log.i("getConnection", "connect success");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    return connection;
}

private boolean login() {
    try {
        // login
        getConnection().login("admin", "123456");
        Log.i("Login", "login success");

        // set status
        Presence presence = new Presence(Presence.Type.available);
        getConnection().sendPacket(presence);
        Log.i("Login", "set status success");

        return true;
    } catch (Exception e) {
        e.printStackTrace();
    }

    return false;
}

private void showMessage(String message) {
    Toast.makeText(this, message, 1000).show();
}

Solution

The 'host-unknown' error may be caused by an incomplete initialization of the connection. After checking if connection == null, make sure to initialize it properly with connection = new XMPPConnection(config);.

Additionally, the issue may stem from not specifying the service name in the constructor of ConnectionConfiguration. The service name should match the XMPP domain. For instance, if the user's email is [email protected], the service name should be "something.com".

You can determine the correct service name by logging the service name after connection.connect() succeeds:

Log.e("Service Name", xmpp.getServiceName());

Then, use the service name in the constructor:

ConnectionConfiguration config = new ConnectionConfiguration(host, port, "something.com");
connection = new XMPPConnection(config);

Conclusion

This approach should address the 'host-unknown' error. For further reference, see the original discussion on Stack Overflow.