public String authenticate(String username, String password, String resource) throws
XMPPException {
// If we send an authentication packet in "get" mode with just the username,
// the server will return the list of authentication protocols it supports.
Authentication discoveryAuth = new Authentication();
discoveryAuth.setType(IQ.Type.GET);
discoveryAuth.setUsername(username);
PacketCollector collector =
connection.createPacketCollector(new PacketIDFilter(discoveryAuth.getPacketID()));
// Send the packet
connection.sendPacket(discoveryAuth);
// Wait up to a certain number of seconds for a response from the server.
IQ response = (IQ) collector.nextResult(SmackConfiguration.getPacketReplyTimeout());
if (response == null) {
throw new XMPPException("No response from the server.");
}
// If the server replied with an error, throw an exception.
else if (response.getType() == IQ.Type.ERROR) {
throw new XMPPException(response.getError());
}
// Otherwise, no error so continue processing.
Authentication authTypes = (Authentication) response;
collector.cancel();
// Now, create the authentication packet we'll send to the server.
Authentication auth = new Authentication();
auth.setUsername(username);
// Figure out if we should use digest or plain text authentication.
if (authTypes.getDigest() != null) {
auth.setDigest(connection.getConnectionID(), password);
}
else if (authTypes.getPassword() != null) {
auth.setPassword(password);
}
else {
throw new XMPPException("Server does not support compatible authentication mechanism.");
}
auth.setResource(resource);
collector = connection.createPacketCollector(new PacketIDFilter(auth.getPacketID()));
// Send the packet.
connection.sendPacket(auth);
// Wait up to a certain number of seconds for a response from the server.
response = (IQ) collector.nextResult(SmackConfiguration.getPacketReplyTimeout());
if (response == null) {