/* * Copyright (C) 2012 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package android.net.nsd; import android.annotation.SdkConstant; import android.annotation.SdkConstant.SdkConstantType; import android.content.Context; import android.os.Binder; import android.os.IBinder; import android.os.Handler; import android.os.HandlerThread; import android.os.Looper; import android.os.Message; import android.os.RemoteException; import android.os.Messenger; import android.text.TextUtils; import android.util.Log; import android.util.SparseArray; import java.util.concurrent.CountDownLatch; import com.android.internal.util.AsyncChannel; import com.android.internal.util.Protocol; /** * The Network Service Discovery Manager class provides the API to discover services * on a network. As an example, if device A and device B are connected over a Wi-Fi * network, a game registered on device A can be discovered by a game on device * B. Another example use case is an application discovering printers on the network. * *

The API currently supports DNS based service discovery and discovery is currently * limited to a local network over Multicast DNS. DNS service discovery is described at * http://files.dns-sd.org/draft-cheshire-dnsext-dns-sd.txt * *

The API is asynchronous and responses to requests from an application are on listener * callbacks on a seperate thread. * *

There are three main operations the API supports - registration, discovery and resolution. * 

 *                          Application start
 *                                 |
 *                                 |
 *                                 |                  onServiceRegistered()
 *                     Register any local services  /
 *                      to be advertised with       \
 *                       registerService()            onRegistrationFailed()
 *                                 |
 *                                 |
 *                          discoverServices()
 *                                 |
 *                      Maintain a list to track
 *                        discovered services
 *                                 |
 *                                 |--------->
 *                                 |          |
 *                                 |      onServiceFound()
 *                                 |          |
 *                                 |     add service to list
 *                                 |          |
 *                                 |<----------
 *                                 |
 *                                 |--------->
 *                                 |          |
 *                                 |      onServiceLost()
 *                                 |          |
 *                                 |   remove service from list
 *                                 |          |
 *                                 |<----------
 *                                 |
 *                                 |
 *                                 | Connect to a service
 *                                 | from list ?
 *                                 |
 *                          resolveService()
 *                                 |
 *                         onServiceResolved()
 *                                 |
 *                     Establish connection to service
 *                     with the host and port information
 *
 *
* An application that needs to advertise itself over a network for other applications to * discover it can do so with a call to {@link #registerService}. If Example is a http based * application that can provide HTML data to peer services, it can register a name "Example" * with service type "_http._tcp". A successful registration is notified with a callback to * {@link RegistrationListener#onServiceRegistered} and a failure to register is notified * over {@link RegistrationListener#onRegistrationFailed} * *

A peer application looking for http services can initiate a discovery for "_http._tcp" * with a call to {@link #discoverServices}. A service found is notified with a callback * to {@link DiscoveryListener#onServiceFound} and a service lost is notified on * {@link DiscoveryListener#onServiceLost}. * *

Once the peer application discovers the "Example" http srevice, and needs to receive data * from the "Example" application, it can initiate a resolve with {@link #resolveService} to * resolve the host and port details for the purpose of establishing a connection. A successful * resolve is notified on {@link ResolveListener#onServiceResolved} and a failure is notified * on {@link ResolveListener#onResolveFailed}. * * Applications can reserve for a service type at * http://www.iana.org/form/ports-service. Existing services can be found at * http://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xml * * Get an instance of this class by calling {@link android.content.Context#getSystemService(String) * Context.getSystemService(Context.NSD_SERVICE)}. * * {@see NsdServiceInfo} */ public final class NsdManager { private static final String TAG = "NsdManager"; INsdManager mService; /** * Broadcast intent action to indicate whether network service discovery is * enabled or disabled. An extra {@link #EXTRA_NSD_STATE} provides the state * information as int. * * @see #EXTRA_NSD_STATE */ @SdkConstant(SdkConstantType.BROADCAST_INTENT_ACTION) public static final String ACTION_NSD_STATE_CHANGED = "android.net.nsd.STATE_CHANGED"; /** * The lookup key for an int that indicates whether network service discovery is enabled * or disabled. Retrieve it with {@link android.content.Intent#getIntExtra(String,int)}. * * @see #NSD_STATE_DISABLED * @see #NSD_STATE_ENABLED */ public static final String EXTRA_NSD_STATE = "nsd_state"; /** * Network service discovery is disabled * * @see #ACTION_NSD_STATE_CHANGED */ public static final int NSD_STATE_DISABLED = 1; /** * Network service discovery is enabled * * @see #ACTION_NSD_STATE_CHANGED */ public static final int NSD_STATE_ENABLED = 2; private static final int BASE = Protocol.BASE_NSD_MANAGER; /** @hide */ public static final int DISCOVER_SERVICES = BASE + 1; /** @hide */ public static final int DISCOVER_SERVICES_STARTED = BASE + 2; /** @hide */ public static final int DISCOVER_SERVICES_FAILED = BASE + 3; /** @hide */ public static final int SERVICE_FOUND = BASE + 4; /** @hide */ public static final int SERVICE_LOST = BASE + 5; /** @hide */ public static final int STOP_DISCOVERY = BASE + 6; /** @hide */ public static final int STOP_DISCOVERY_FAILED = BASE + 7; /** @hide */ public static final int STOP_DISCOVERY_SUCCEEDED = BASE + 8; /** @hide */ public static final int REGISTER_SERVICE = BASE + 9; /** @hide */ public static final int REGISTER_SERVICE_FAILED = BASE + 10; /** @hide */ public static final int REGISTER_SERVICE_SUCCEEDED = BASE + 11; /** @hide */ public static final int UNREGISTER_SERVICE = BASE + 12; /** @hide */ public static final int UNREGISTER_SERVICE_FAILED = BASE + 13; /** @hide */ public static final int UNREGISTER_SERVICE_SUCCEEDED = BASE + 14; /** @hide */ public static final int RESOLVE_SERVICE = BASE + 18; /** @hide */ public static final int RESOLVE_SERVICE_FAILED = BASE + 19; /** @hide */ public static final int RESOLVE_SERVICE_SUCCEEDED = BASE + 20; /** @hide */ public static final int ENABLE = BASE + 24; /** @hide */ public static final int DISABLE = BASE + 25; /** @hide */ public static final int NATIVE_DAEMON_EVENT = BASE + 26; /** Dns based service discovery protocol */ public static final int PROTOCOL_DNS_SD = 0x0001; private Context mContext; private static final int INVALID_LISTENER_KEY = 0; private int mListenerKey = 1; private final SparseArray mListenerMap = new SparseArray(); private final SparseArray mServiceMap = new SparseArray(); private final Object mMapLock = new Object(); private final AsyncChannel mAsyncChannel = new AsyncChannel(); private ServiceHandler mHandler; private final CountDownLatch mConnected = new CountDownLatch(1); /** * Create a new Nsd instance. Applications use * {@link android.content.Context#getSystemService Context.getSystemService()} to retrieve * {@link android.content.Context#NSD_SERVICE Context.NSD_SERVICE}. * @param service the Binder interface * @hide - hide this because it takes in a parameter of type INsdManager, which * is a system private class. */ public NsdManager(Context context, INsdManager service) { mService = service; mContext = context; init(); } /** * Failures are passed with {@link RegistrationListener#onRegistrationFailed}, * {@link RegistrationListener#onUnregistrationFailed}, * {@link DiscoveryListener#onStartDiscoveryFailed}, * {@link DiscoveryListener#onStopDiscoveryFailed} or {@link ResolveListener#onResolveFailed}. * * Indicates that the operation failed due to an internal error. */ public static final int FAILURE_INTERNAL_ERROR = 0; /** * Indicates that the operation failed because it is already active. */ public static final int FAILURE_ALREADY_ACTIVE = 3; /** * Indicates that the operation failed because the maximum outstanding * requests from the applications have reached. */ public static final int FAILURE_MAX_LIMIT = 4; /** Interface for callback invocation for service discovery */ public interface DiscoveryListener { public void onStartDiscoveryFailed(String serviceType, int errorCode); public void onStopDiscoveryFailed(String serviceType, int errorCode); public void onDiscoveryStarted(String serviceType); public void onDiscoveryStopped(String serviceType); public void onServiceFound(NsdServiceInfo serviceInfo); public void onServiceLost(NsdServiceInfo serviceInfo); } /** Interface for callback invocation for service registration */ public interface RegistrationListener { public void onRegistrationFailed(NsdServiceInfo serviceInfo, int errorCode); public void onUnregistrationFailed(NsdServiceInfo serviceInfo, int errorCode); public void onServiceRegistered(NsdServiceInfo serviceInfo); public void onServiceUnregistered(NsdServiceInfo serviceInfo); } /** Interface for callback invocation for service resolution */ public interface ResolveListener { public void onResolveFailed(NsdServiceInfo serviceInfo, int errorCode); public void onServiceResolved(NsdServiceInfo serviceInfo); } private class ServiceHandler extends Handler { ServiceHandler(Looper looper) { super(looper); } @Override public void handleMessage(Message message) { Object listener = getListener(message.arg2); boolean listenerRemove = true; switch (message.what) { case AsyncChannel.CMD_CHANNEL_HALF_CONNECTED: mAsyncChannel.sendMessage(AsyncChannel.CMD_CHANNEL_FULL_CONNECTION); mConnected.countDown(); break; case AsyncChannel.CMD_CHANNEL_FULLY_CONNECTED: // Ignore break; case AsyncChannel.CMD_CHANNEL_DISCONNECTED: Log.e(TAG, "Channel lost"); break; case DISCOVER_SERVICES_STARTED: String s = ((NsdServiceInfo) message.obj).getServiceType(); ((DiscoveryListener) listener).onDiscoveryStarted(s); // Keep listener until stop discovery listenerRemove = false; break; case DISCOVER_SERVICES_FAILED: ((DiscoveryListener) listener).onStartDiscoveryFailed( getNsdService(message.arg2).getServiceType(), message.arg1); break; case SERVICE_FOUND: ((DiscoveryListener) listener).onServiceFound((NsdServiceInfo) message.obj); // Keep listener until stop discovery listenerRemove = false; break; case SERVICE_LOST: ((DiscoveryListener) listener).onServiceLost((NsdServiceInfo) message.obj); // Keep listener until stop discovery listenerRemove = false; break; case STOP_DISCOVERY_FAILED: ((DiscoveryListener) listener).onStopDiscoveryFailed( getNsdService(message.arg2).getServiceType(), message.arg1); break; case STOP_DISCOVERY_SUCCEEDED: ((DiscoveryListener) listener).onDiscoveryStopped( getNsdService(message.arg2).getServiceType()); break; case REGISTER_SERVICE_FAILED: ((RegistrationListener) listener).onRegistrationFailed( getNsdService(message.arg2), message.arg1); break; case REGISTER_SERVICE_SUCCEEDED: ((RegistrationListener) listener).onServiceRegistered( (NsdServiceInfo) message.obj); // Keep listener until unregister listenerRemove = false; break; case UNREGISTER_SERVICE_FAILED: ((RegistrationListener) listener).onUnregistrationFailed( getNsdService(message.arg2), message.arg1); break; case UNREGISTER_SERVICE_SUCCEEDED: ((RegistrationListener) listener).onServiceUnregistered( getNsdService(message.arg2)); break; case RESOLVE_SERVICE_FAILED: ((ResolveListener) listener).onResolveFailed( getNsdService(message.arg2), message.arg1); break; case RESOLVE_SERVICE_SUCCEEDED: ((ResolveListener) listener).onServiceResolved((NsdServiceInfo) message.obj); break; default: Log.d(TAG, "Ignored " + message); break; } if (listenerRemove) { removeListener(message.arg2); } } } private int putListener(Object listener, NsdServiceInfo s) { if (listener == null) return INVALID_LISTENER_KEY; int key; synchronized (mMapLock) { do { key = mListenerKey++; } while (key == INVALID_LISTENER_KEY); mListenerMap.put(key, listener); mServiceMap.put(key, s); } return key; } private Object getListener(int key) { if (key == INVALID_LISTENER_KEY) return null; synchronized (mMapLock) { return mListenerMap.get(key); } } private NsdServiceInfo getNsdService(int key) { synchronized (mMapLock) { return mServiceMap.get(key); } } private void removeListener(int key) { if (key == INVALID_LISTENER_KEY) return; synchronized (mMapLock) { mListenerMap.remove(key); mServiceMap.remove(key); } } private int getListenerKey(Object listener) { synchronized (mMapLock) { int valueIndex = mListenerMap.indexOfValue(listener); if (valueIndex != -1) { return mListenerMap.keyAt(valueIndex); } } return INVALID_LISTENER_KEY; } /** * Initialize AsyncChannel */ private void init() { final Messenger messenger = getMessenger(); if (messenger == null) throw new RuntimeException("Failed to initialize"); HandlerThread t = new HandlerThread("NsdManager"); t.start(); mHandler = new ServiceHandler(t.getLooper()); mAsyncChannel.connect(mContext, mHandler, messenger); try { mConnected.await(); } catch (InterruptedException e) { Log.e(TAG, "interrupted wait at init"); } } /** * Register a service to be discovered by other services. * *

The function call immediately returns after sending a request to register service * to the framework. The application is notified of a success to initiate * discovery through the callback {@link RegistrationListener#onServiceRegistered} or a failure * through {@link RegistrationListener#onRegistrationFailed}. * * @param serviceInfo The service being registered * @param protocolType The service discovery protocol * @param listener The listener notifies of a successful registration and is used to * unregister this service through a call on {@link #unregisterService}. Cannot be null. */ public void registerService(NsdServiceInfo serviceInfo, int protocolType, RegistrationListener listener) { if (TextUtils.isEmpty(serviceInfo.getServiceName()) || TextUtils.isEmpty(serviceInfo.getServiceType())) { throw new IllegalArgumentException("Service name or type cannot be empty"); } if (serviceInfo.getPort() <= 0) { throw new IllegalArgumentException("Invalid port number"); } if (listener == null) { throw new IllegalArgumentException("listener cannot be null"); } if (protocolType != PROTOCOL_DNS_SD) { throw new IllegalArgumentException("Unsupported protocol"); } mAsyncChannel.sendMessage(REGISTER_SERVICE, 0, putListener(listener, serviceInfo), serviceInfo); } /** * Unregister a service registered through {@link #registerService}. A successful * unregister is notified to the application with a call to * {@link RegistrationListener#onServiceUnregistered}. * * @param listener This should be the listener object that was passed to * {@link #registerService}. It identifies the service that should be unregistered * and notifies of a successful unregistration. */ public void unregisterService(RegistrationListener listener) { int id = getListenerKey(listener); if (id == INVALID_LISTENER_KEY) { throw new IllegalArgumentException("listener not registered"); } if (listener == null) { throw new IllegalArgumentException("listener cannot be null"); } mAsyncChannel.sendMessage(UNREGISTER_SERVICE, 0, id); } /** * Initiate service discovery to browse for instances of a service type. Service discovery * consumes network bandwidth and will continue until the application calls * {@link #stopServiceDiscovery}. * *

The function call immediately returns after sending a request to start service * discovery to the framework. The application is notified of a success to initiate * discovery through the callback {@link DiscoveryListener#onDiscoveryStarted} or a failure * through {@link DiscoveryListener#onStartDiscoveryFailed}. * *

Upon successful start, application is notified when a service is found with * {@link DiscoveryListener#onServiceFound} or when a service is lost with * {@link DiscoveryListener#onServiceLost}. * *

Upon failure to start, service discovery is not active and application does * not need to invoke {@link #stopServiceDiscovery} * * @param serviceType The service type being discovered. Examples include "_http._tcp" for * http services or "_ipp._tcp" for printers * @param protocolType The service discovery protocol * @param listener The listener notifies of a successful discovery and is used * to stop discovery on this serviceType through a call on {@link #stopServiceDiscovery}. * Cannot be null. */ public void discoverServices(String serviceType, int protocolType, DiscoveryListener listener) { if (listener == null) { throw new IllegalArgumentException("listener cannot be null"); } if (TextUtils.isEmpty(serviceType)) { throw new IllegalArgumentException("Service type cannot be empty"); } if (protocolType != PROTOCOL_DNS_SD) { throw new IllegalArgumentException("Unsupported protocol"); } NsdServiceInfo s = new NsdServiceInfo(); s.setServiceType(serviceType); mAsyncChannel.sendMessage(DISCOVER_SERVICES, 0, putListener(listener, s), s); } /** * Stop service discovery initiated with {@link #discoverServices}. An active service * discovery is notified to the application with {@link DiscoveryListener#onDiscoveryStarted} * and it stays active until the application invokes a stop service discovery. A successful * stop is notified to with a call to {@link DiscoveryListener#onDiscoveryStopped}. * *

Upon failure to stop service discovery, application is notified through * {@link DiscoveryListener#onStopDiscoveryFailed}. * * @param listener This should be the listener object that was passed to {@link #discoverServices}. * It identifies the discovery that should be stopped and notifies of a successful stop. */ public void stopServiceDiscovery(DiscoveryListener listener) { int id = getListenerKey(listener); if (id == INVALID_LISTENER_KEY) { throw new IllegalArgumentException("service discovery not active on listener"); } if (listener == null) { throw new IllegalArgumentException("listener cannot be null"); } mAsyncChannel.sendMessage(STOP_DISCOVERY, 0, id); } /** * Resolve a discovered service. An application can resolve a service right before * establishing a connection to fetch the IP and port details on which to setup * the connection. * * @param serviceInfo service to be resolved * @param listener to receive callback upon success or failure. Cannot be null. */ public void resolveService(NsdServiceInfo serviceInfo, ResolveListener listener) { if (TextUtils.isEmpty(serviceInfo.getServiceName()) || TextUtils.isEmpty(serviceInfo.getServiceType())) { throw new IllegalArgumentException("Service name or type cannot be empty"); } if (listener == null) { throw new IllegalArgumentException("listener cannot be null"); } mAsyncChannel.sendMessage(RESOLVE_SERVICE, 0, putListener(listener, serviceInfo), serviceInfo); } /** Internal use only @hide */ public void setEnabled(boolean enabled) { try { mService.setEnabled(enabled); } catch (RemoteException e) { } } /** * Get a reference to NetworkService handler. This is used to establish * an AsyncChannel communication with the service * * @return Messenger pointing to the NetworkService handler */ private Messenger getMessenger() { try { return mService.getMessenger(); } catch (RemoteException e) { return null; } } }