Push notifications

mastodon/build.gradle

@@ -10,7 +10,7 @@ android {
 		applicationId "org.joinmastodon.android"
 		minSdk 23
 		targetSdk 31
-		versionCode 18
+		versionCode 20
 		versionName "0.1"
 	}
 

mastodon/src/main/AndroidManifest.xml

@@ -4,6 +4,10 @@
 
 	<uses-permission android:name="android.permission.INTERNET"/>
 	<uses-permission android:name="android.permission.FOREGROUND_SERVICE"/>
+	<uses-permission android:name="${applicationId}.permission.C2D_MESSAGE"/>
+	<uses-permission android:name="com.google.android.c2dm.permission.RECEIVE"/>
+
+	<permission android:name="${applicationId}.permission.C2D_MESSAGE" android:protectionLevel="signature"/>
 
 	<application
 		android:name=".MastodonApp"
@@ -15,7 +19,7 @@
 		android:theme="@style/Theme.Mastodon.AutoLightDark"
 		android:largeHeap="true">
 
-		<activity android:name=".MainActivity" android:exported="true" android:configChanges="orientation|screenSize" android:windowSoftInputMode="adjustResize">
+		<activity android:name=".MainActivity" android:exported="true" android:configChanges="orientation|screenSize" android:windowSoftInputMode="adjustResize" android:launchMode="singleTask">
 			<intent-filter>
 				<action android:name="android.intent.action.MAIN"/>
 				<category android:name="android.intent.category.LAUNCHER"/>
@@ -32,6 +36,18 @@
 
 		<service android:name=".AudioPlayerService" android:foregroundServiceType="mediaPlayback"/>
 
+		<receiver android:name=".PushNotificationReceiver" android:exported="true" android:permission="com.google.android.c2dm.permission.SEND">
+			<intent-filter>
+				<action android:name="com.google.android.c2dm.intent.RECEIVE" />
+			</intent-filter>
+		</receiver>
+		<receiver android:name=".api.PushSubscriptionManager$RegistrationReceiver" android:exported="true" android:permission="com.google.android.c2dm.permission.SEND">
+			<intent-filter>
+				<action android:name="com.google.android.c2dm.intent.REGISTRATION"/>
+				<category android:name="me.grishka.fcmtest"/>
+			</intent-filter>
+		</receiver>
+
 	</application>
 
 </manifest>

mastodon/src/main/java/org/joinmastodon/android/MainActivity.java

@@ -2,13 +2,20 @@ package org.joinmastodon.android;
 
 import android.app.Application;
 import android.app.Fragment;
+import android.content.Intent;
 import android.os.Bundle;
+import android.util.Log;
 
+import org.joinmastodon.android.api.ObjectValidationException;
 import org.joinmastodon.android.api.session.AccountSession;
 import org.joinmastodon.android.api.session.AccountSessionManager;
 import org.joinmastodon.android.fragments.HomeFragment;
+import org.joinmastodon.android.fragments.ProfileFragment;
 import org.joinmastodon.android.fragments.SplashFragment;
+import org.joinmastodon.android.fragments.ThreadFragment;
 import org.joinmastodon.android.fragments.onboarding.AccountActivationFragment;
+import org.joinmastodon.android.model.Notification;
+import org.parceler.Parcels;
 
 import java.lang.reflect.InvocationTargetException;
 
@@ -25,12 +32,29 @@ public class MainActivity extends FragmentStackActivity{
 				showFragmentClearingBackStack(new SplashFragment());
 			}else{
 				AccountSessionManager.getInstance().maybeUpdateLocalInfo();
-				AccountSession session=AccountSessionManager.getInstance().getLastActiveAccount();
+				AccountSession session;
 				Bundle args=new Bundle();
+				Intent intent=getIntent();
+				if(intent.getBooleanExtra("fromNotification", false)){
+					String accountID=intent.getStringExtra("accountID");
+					try{
+						session=AccountSessionManager.getInstance().getAccount(accountID);
+						if(!intent.hasExtra("notification"))
+							args.putString("tab", "notifications");
+					}catch(IllegalStateException x){
+						session=AccountSessionManager.getInstance().getLastActiveAccount();
+					}
+				}else{
+					session=AccountSessionManager.getInstance().getLastActiveAccount();
+				}
 				args.putString("account", session.getID());
 				Fragment fragment=session.activated ? new HomeFragment() : new AccountActivationFragment();
 				fragment.setArguments(args);
 				showFragmentClearingBackStack(fragment);
+				if(intent.getBooleanExtra("fromNotification", false) && intent.hasExtra("notification")){
+					Notification notification=Parcels.unwrap(intent.getParcelableExtra("notification"));
+					showFragmentForNotification(notification, session.getID());
+				}
 			}
 		}
 
@@ -41,4 +65,52 @@ public class MainActivity extends FragmentStackActivity{
 			}catch(ClassNotFoundException|NoSuchMethodException|IllegalAccessException|InvocationTargetException ignore){}
 		}
 	}
+
+	@Override
+	protected void onNewIntent(Intent intent){
+		super.onNewIntent(intent);
+		if(intent.getBooleanExtra("fromNotification", false)){
+			String accountID=intent.getStringExtra("accountID");
+			AccountSession accountSession;
+			try{
+				accountSession=AccountSessionManager.getInstance().getAccount(accountID);
+			}catch(IllegalStateException x){
+				return;
+			}
+			if(intent.hasExtra("notification")){
+				Notification notification=Parcels.unwrap(intent.getParcelableExtra("notification"));
+				showFragmentForNotification(notification, accountID);
+			}else{
+				AccountSessionManager.getInstance().setLastActiveAccountID(accountID);
+				Bundle args=new Bundle();
+				args.putString("account", accountID);
+				args.putString("tab", "notifications");
+				Fragment fragment=new HomeFragment();
+				fragment.setArguments(args);
+				showFragmentClearingBackStack(fragment);
+			}
+		}
+	}
+
+	private void showFragmentForNotification(Notification notification, String accountID){
+		Fragment fragment;
+		Bundle args=new Bundle();
+		args.putString("account", accountID);
+		args.putBoolean("_can_go_back", true);
+		try{
+			notification.postprocess();
+		}catch(ObjectValidationException x){
+			Log.w("MainActivity", x);
+			return;
+		}
+		if(notification.status!=null){
+			fragment=new ThreadFragment();
+			args.putParcelable("status", Parcels.wrap(notification.status));
+		}else{
+			fragment=new ProfileFragment();
+			args.putParcelable("profileAccount", Parcels.wrap(notification.account));
+		}
+		fragment.setArguments(args);
+		showFragment(fragment);
+	}
 }

mastodon/src/main/java/org/joinmastodon/android/MastodonApp.java

@@ -4,6 +4,8 @@ import android.annotation.SuppressLint;
 import android.app.Application;
 import android.content.Context;
 
+import org.joinmastodon.android.api.PushSubscriptionManager;
+
 import java.lang.reflect.InvocationTargetException;
 
 import me.grishka.appkit.imageloader.ImageCache;
@@ -23,5 +25,7 @@ public class MastodonApp extends Application{
 		ImageCache.setParams(params);
 		NetworkUtils.setUserAgent("MastodonAndroid/"+BuildConfig.VERSION_NAME);
 		context=getApplicationContext();
+
+		PushSubscriptionManager.tryRegisterFCM();
 	}
 }

mastodon/src/main/java/org/joinmastodon/android/PushNotificationReceiver.java

@@ -0,0 +1,140 @@
+package org.joinmastodon.android;
+
+import android.app.Notification;
+import android.app.NotificationChannel;
+import android.app.NotificationChannelGroup;
+import android.app.NotificationManager;
+import android.app.PendingIntent;
+import android.content.BroadcastReceiver;
+import android.content.Context;
+import android.content.Intent;
+import android.graphics.Bitmap;
+import android.graphics.drawable.Drawable;
+import android.graphics.drawable.Icon;
+import android.os.Build;
+import android.os.Bundle;
+import android.text.TextUtils;
+import android.util.Log;
+
+import org.joinmastodon.android.api.MastodonAPIController;
+import org.joinmastodon.android.api.requests.notifications.GetNotificationByID;
+import org.joinmastodon.android.api.session.AccountSessionManager;
+import org.joinmastodon.android.model.Account;
+import org.joinmastodon.android.model.PushNotification;
+import org.joinmastodon.android.ui.utils.UiUtils;
+import org.parceler.Parcels;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+
+import me.grishka.appkit.api.Callback;
+import me.grishka.appkit.api.ErrorResponse;
+import me.grishka.appkit.imageloader.ImageCache;
+import me.grishka.appkit.imageloader.requests.UrlImageLoaderRequest;
+import me.grishka.appkit.utils.V;
+
+public class PushNotificationReceiver extends BroadcastReceiver{
+	private static final String TAG="PushNotificationReceive";
+
+	public static final int NOTIFICATION_ID=178;
+
+	@Override
+	public void onReceive(Context context, Intent intent){
+		if(BuildConfig.DEBUG){
+			Log.e(TAG, "received: "+intent);
+			Bundle extras=intent.getExtras();
+			for(String key : extras.keySet()){
+				Log.i(TAG, key+" -> "+extras.get(key));
+			}
+		}
+		if("com.google.android.c2dm.intent.RECEIVE".equals(intent.getAction())){
+			String k=intent.getStringExtra("k");
+			String p=intent.getStringExtra("p");
+			String s=intent.getStringExtra("s");
+			String accountID=intent.getStringExtra("x");
+			if(!TextUtils.isEmpty(accountID) && !TextUtils.isEmpty(k) && !TextUtils.isEmpty(p) && !TextUtils.isEmpty(s)){
+				MastodonAPIController.runInBackground(()->{
+					try{
+						PushNotification pn=AccountSessionManager.getInstance().getAccount(accountID).getPushSubscriptionManager().decryptNotification(k, p, s);
+						new GetNotificationByID(pn.notificationId+"")
+								.setCallback(new Callback<>(){
+									@Override
+									public void onSuccess(org.joinmastodon.android.model.Notification result){
+										MastodonAPIController.runInBackground(()->PushNotificationReceiver.this.notify(context, pn, accountID, result));
+									}
+
+									@Override
+									public void onError(ErrorResponse error){
+										MastodonAPIController.runInBackground(()->PushNotificationReceiver.this.notify(context, pn, accountID, null));
+									}
+								})
+								.exec(accountID);
+					}catch(Exception x){
+						Log.w(TAG, x);
+					}
+				});
+			}else{
+				Log.w(TAG, "onReceive: invalid push notification format");
+			}
+		}
+	}
+
+	private void notify(Context context, PushNotification pn, String accountID, org.joinmastodon.android.model.Notification notification){
+		NotificationManager nm=context.getSystemService(NotificationManager.class);
+		Account self=AccountSessionManager.getInstance().getAccount(accountID).self;
+		String accountName="@"+self.username+"@"+AccountSessionManager.getInstance().getAccount(accountID).domain;
+		Notification.Builder builder;
+		if(Build.VERSION.SDK_INT>=Build.VERSION_CODES.O){
+			boolean hasGroup=false;
+			List<NotificationChannelGroup> channelGroups=nm.getNotificationChannelGroups();
+			for(NotificationChannelGroup group:channelGroups){
+				if(group.getId().equals(accountID)){
+					hasGroup=true;
+					break;
+				}
+			}
+			if(!hasGroup){
+				NotificationChannelGroup group=new NotificationChannelGroup(accountID, accountName);
+				nm.createNotificationChannelGroup(group);
+				List<NotificationChannel> channels=Arrays.stream(PushNotification.Type.values())
+						.map(type->{
+							NotificationChannel channel=new NotificationChannel(accountID+"_"+type, context.getString(type.localizedName), NotificationManager.IMPORTANCE_DEFAULT);
+							channel.setGroup(accountID);
+							return channel;
+						})
+						.collect(Collectors.toList());
+				nm.createNotificationChannels(channels);
+			}
+			builder=new Notification.Builder(context, accountID+"_"+pn.notificationType);
+		}else{
+			builder=new Notification.Builder(context)
+					.setPriority(Notification.PRIORITY_DEFAULT)
+					.setDefaults(Notification.DEFAULT_SOUND | Notification.DEFAULT_VIBRATE);
+		}
+		Drawable avatar=ImageCache.getInstance(context).get(new UrlImageLoaderRequest(pn.icon, V.dp(50), V.dp(50)));
+		Intent contentIntent=new Intent(context, MainActivity.class);
+		contentIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
+		contentIntent.putExtra("fromNotification", true);
+		contentIntent.putExtra("accountID", accountID);
+		if(notification!=null){
+			contentIntent.putExtra("notification", Parcels.wrap(notification));
+		}
+		builder.setContentTitle(pn.title)
+				.setContentText(pn.body)
+				.setStyle(new Notification.BigTextStyle().bigText(pn.body))
+				.setSmallIcon(R.drawable.ic_ntf_logo)
+				.setContentIntent(PendingIntent.getActivity(context, accountID.hashCode() & 0xFFFF, contentIntent, PendingIntent.FLAG_IMMUTABLE | PendingIntent.FLAG_CANCEL_CURRENT))
+				.setWhen(System.currentTimeMillis())
+				.setShowWhen(true)
+				.setAutoCancel(true)
+				.setColor(context.getColor(R.color.primary_700));
+		if(avatar!=null){
+			builder.setLargeIcon(UiUtils.getBitmapFromDrawable(avatar));
+		}
+		if(AccountSessionManager.getInstance().getLoggedInAccounts().size()>1){
+			builder.setSubText(accountName);
+		}
+		nm.notify(accountID, NOTIFICATION_ID, builder.build());
+	}
+}

mastodon/src/main/java/org/joinmastodon/android/api/PushSubscriptionManager.java

@@ -0,0 +1,349 @@
+package org.joinmastodon.android.api;
+
+import android.app.PendingIntent;
+import android.content.BroadcastReceiver;
+import android.content.Context;
+import android.content.Intent;
+import android.content.SharedPreferences;
+import android.os.Bundle;
+import android.text.TextUtils;
+import android.util.Base64;
+import android.util.Log;
+
+import org.joinmastodon.android.BuildConfig;
+import org.joinmastodon.android.MastodonApp;
+import org.joinmastodon.android.api.requests.notifications.RegisterForPushNotifications;
+import org.joinmastodon.android.api.session.AccountSession;
+import org.joinmastodon.android.api.session.AccountSessionManager;
+import org.joinmastodon.android.model.PushNotification;
+import org.joinmastodon.android.model.PushSubscription;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.security.InvalidAlgorithmParameterException;
+import java.security.InvalidKeyException;
+import java.security.KeyFactory;
+import java.security.KeyPair;
+import java.security.KeyPairGenerator;
+import java.security.NoSuchAlgorithmException;
+import java.security.PrivateKey;
+import java.security.PublicKey;
+import java.security.SecureRandom;
+import java.security.interfaces.ECPublicKey;
+import java.security.spec.ECGenParameterSpec;
+import java.security.spec.ECPoint;
+import java.security.spec.InvalidKeySpecException;
+import java.security.spec.PKCS8EncodedKeySpec;
+import java.security.spec.X509EncodedKeySpec;
+import java.util.Arrays;
+
+import javax.crypto.BadPaddingException;
+import javax.crypto.Cipher;
+import javax.crypto.IllegalBlockSizeException;
+import javax.crypto.KeyAgreement;
+import javax.crypto.Mac;
+import javax.crypto.NoSuchPaddingException;
+import javax.crypto.SecretKey;
+import javax.crypto.spec.GCMParameterSpec;
+import javax.crypto.spec.SecretKeySpec;
+
+import me.grishka.appkit.api.Callback;
+import me.grishka.appkit.api.ErrorResponse;
+
+public class PushSubscriptionManager{
+	private static final String FCM_SENDER_ID="449535203550";
+	private static final String EC_CURVE_NAME="prime256v1";
+	private static final byte[] P256_HEAD=new byte[]{(byte)0x30,(byte)0x59,(byte)0x30,(byte)0x13,(byte)0x06,(byte)0x07,(byte)0x2a,
+			(byte)0x86,(byte)0x48,(byte)0xce,(byte)0x3d,(byte)0x02,(byte)0x01,(byte)0x06,(byte)0x08,(byte)0x2a,(byte)0x86,
+			(byte)0x48,(byte)0xce,(byte)0x3d,(byte)0x03,(byte)0x01,(byte)0x07,(byte)0x03,(byte)0x42,(byte)0x00};
+	private static final int[] BASE85_DECODE_TABLE={
+			0xff, 0x44, 0xff, 0x54, 0x53, 0x52, 0x48, 0xff,
+			0x4b, 0x4c, 0x46, 0x41, 0xff, 0x3f, 0x3e, 0x45,
+			0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+			0x08, 0x09, 0x40, 0xff, 0x49, 0x42, 0x4a, 0x47,
+			0x51, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a,
+			0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 0x30, 0x31, 0x32,
+			0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a,
+			0x3b, 0x3c, 0x3d, 0x4d, 0xff, 0x4e, 0x43, 0xff,
+			0xff, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10,
+			0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18,
+			0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, 0x20,
+			0x21, 0x22, 0x23, 0x4f, 0xff, 0x50, 0xff, 0xff
+	};
+
+	private static final String TAG="PushSubscriptionManager";
+	public static final String EXTRA_APPLICATION_PENDING_INTENT = "app";
+	public static final String GSF_PACKAGE = "com.google.android.gms";
+	/** Internal parameter used to indicate a 'subtype'. Will not be stored in DB for Nacho. */
+	private static final String EXTRA_SUBTYPE = "subtype";
+	/** Extra used to indicate which senders (Google API project IDs) can send messages to the app */
+	private static final String EXTRA_SENDER = "sender";
+	private static final String EXTRA_SCOPE = "scope";
+	private static final String KID_VALUE="|ID|1|"; // request ID?
+
+	private static String deviceToken;
+	private String accountID;
+	private PrivateKey privateKey;
+	private PublicKey publicKey;
+	private PublicKey serverKey;
+	private byte[] authKey;
+
+	public PushSubscriptionManager(String accountID){
+		this.accountID=accountID;
+	}
+
+	public static void tryRegisterFCM(){
+		deviceToken=getPrefs().getString("deviceToken", null);
+		if(!TextUtils.isEmpty(deviceToken)){
+			registerAllAccountsForPush();
+			return;
+		}
+		Intent intent = new Intent("com.google.iid.TOKEN_REQUEST");
+		intent.setPackage(GSF_PACKAGE);
+		intent.putExtra(EXTRA_APPLICATION_PENDING_INTENT,
+				PendingIntent.getBroadcast(MastodonApp.context, 0, new Intent(), PendingIntent.FLAG_IMMUTABLE));
+		intent.putExtra(EXTRA_SENDER, FCM_SENDER_ID);
+		intent.putExtra(EXTRA_SUBTYPE, FCM_SENDER_ID);
+		intent.putExtra(EXTRA_SCOPE, "*");
+		intent.putExtra("kid", KID_VALUE);
+		MastodonApp.context.sendBroadcast(intent);
+	}
+
+	private static SharedPreferences getPrefs(){
+		return MastodonApp.context.getSharedPreferences("push", Context.MODE_PRIVATE);
+	}
+
+	public static boolean arePushNotificationsAvailable(){
+		return !TextUtils.isEmpty(deviceToken);
+	}
+
+	public void registerAccountForPush(){
+		if(TextUtils.isEmpty(deviceToken))
+			throw new IllegalStateException("No device push token available");
+		MastodonAPIController.runInBackground(()->{
+			Log.d(TAG, "registerAccountForPush: started for "+accountID);
+			String encodedPublicKey, encodedAuthKey;
+			try{
+				KeyPairGenerator generator=KeyPairGenerator.getInstance("EC");
+				ECGenParameterSpec spec=new ECGenParameterSpec(EC_CURVE_NAME);
+				generator.initialize(spec);
+				KeyPair keyPair=generator.generateKeyPair();
+				publicKey=keyPair.getPublic();
+				privateKey=keyPair.getPrivate();
+				encodedPublicKey=Base64.encodeToString(serializeRawPublicKey(publicKey), Base64.URL_SAFE | Base64.NO_WRAP | Base64.NO_PADDING);
+				authKey=new byte[16];
+				new SecureRandom().nextBytes(authKey);
+				AccountSession session=AccountSessionManager.getInstance().getAccount(accountID);
+				session.pushPrivateKey=Base64.encodeToString(privateKey.getEncoded(), Base64.URL_SAFE | Base64.NO_WRAP | Base64.NO_PADDING);
+				session.pushPublicKey=Base64.encodeToString(publicKey.getEncoded(), Base64.URL_SAFE | Base64.NO_WRAP | Base64.NO_PADDING);
+				session.pushAuthKey=encodedAuthKey=Base64.encodeToString(authKey, Base64.URL_SAFE | Base64.NO_WRAP | Base64.NO_PADDING);
+				AccountSessionManager.getInstance().writeAccountsFile();
+			}catch(NoSuchAlgorithmException|InvalidAlgorithmParameterException e){
+				Log.e(TAG, "registerAccountForPush: error generating encryption key", e);
+				return;
+			}
+			new RegisterForPushNotifications(deviceToken, encodedPublicKey, encodedAuthKey, PushSubscription.Alerts.ofAll(), accountID)
+					.setCallback(new Callback<>(){
+						@Override
+						public void onSuccess(PushSubscription result){
+							MastodonAPIController.runInBackground(()->{
+								serverKey=deserializeRawPublicKey(Base64.decode(result.serverKey, Base64.URL_SAFE));
+
+								if(serverKey!=null){
+									AccountSession session=AccountSessionManager.getInstance().getAccount(accountID);
+									session.pushServerKey=Base64.encodeToString(serverKey.getEncoded(), Base64.URL_SAFE | Base64.NO_WRAP | Base64.NO_PADDING);
+									AccountSessionManager.getInstance().writeAccountsFile();
+									Log.d(TAG, "Successfully registered "+accountID+" for push notifications");
+								}
+							});
+						}
+
+						@Override
+						public void onError(ErrorResponse error){
+
+						}
+					})
+					.exec(accountID);
+		});
+	}
+
+	private PublicKey deserializeRawPublicKey(byte[] rawBytes){
+		if(rawBytes.length!=65 && rawBytes.length!=64)
+			return null;
+		try{
+			KeyFactory kf=KeyFactory.getInstance("EC");
+			ByteArrayOutputStream os=new ByteArrayOutputStream();
+			os.write(P256_HEAD);
+			if(rawBytes.length==64)
+				os.write(4);
+			os.write(rawBytes);
+			return kf.generatePublic(new X509EncodedKeySpec(os.toByteArray()));
+		}catch(NoSuchAlgorithmException|InvalidKeySpecException|IOException x){
+			Log.e(TAG, "deserializeRawPublicKey", x);
+		}
+		return null;
+	}
+
+	private byte[] serializeRawPublicKey(PublicKey key){
+		ECPoint point=((ECPublicKey)key).getW();
+		byte[] x=point.getAffineX().toByteArray();
+		byte[] y=point.getAffineY().toByteArray();
+		if(x.length>32)
+			x=Arrays.copyOfRange(x, x.length-32, x.length);
+		if(y.length>32)
+			y=Arrays.copyOfRange(y, y.length-32, y.length);
+		byte[] result=new byte[65];
+		result[0]=4;
+		System.arraycopy(x, 0, result, 1+(32-x.length), x.length);
+		System.arraycopy(y, 0, result, result.length-y.length, y.length);
+		return result;
+	}
+
+	private static byte[] decode85(String in){
+		ByteArrayOutputStream data=new ByteArrayOutputStream();
+		int block=0;
+		int n=0;
+		for(char c:in.toCharArray()){
+			if(c>=32 && c<128 && BASE85_DECODE_TABLE[c-32]!=0xff){
+				int value=BASE85_DECODE_TABLE[c-32];
+				block=block*85+value;
+				n++;
+				if(n==5){
+					data.write(block >> 24);
+					data.write(block >> 16);
+					data.write(block >> 8);
+					data.write(block);
+					block=0;
+					n=0;
+				}
+			}
+		}
+		if(n>=4)
+			data.write(block >> 16);
+		if(n>=3)
+			data.write(block >> 8);
+		if(n>=2)
+			data.write(block);
+		return data.toByteArray();
+	}
+
+	public PushNotification decryptNotification(String k, String p, String s){
+		byte[] serverKeyBytes=decode85(k);
+		byte[] payload=decode85(p);
+		byte[] salt=decode85(s);
+		PublicKey serverKey=deserializeRawPublicKey(serverKeyBytes);
+		if(privateKey==null){
+			try{
+				KeyFactory kf=KeyFactory.getInstance("EC");
+				privateKey=kf.generatePrivate(new PKCS8EncodedKeySpec(Base64.decode(AccountSessionManager.getInstance().getAccount(accountID).pushPrivateKey, Base64.URL_SAFE)));
+				publicKey=kf.generatePublic(new X509EncodedKeySpec(Base64.decode(AccountSessionManager.getInstance().getAccount(accountID).pushPublicKey, Base64.URL_SAFE)));
+				authKey=Base64.decode(AccountSessionManager.getInstance().getAccount(accountID).pushAuthKey, Base64.URL_SAFE);
+			}catch(NoSuchAlgorithmException|InvalidKeySpecException x){
+				Log.e(TAG, "decryptNotification: error loading private key", x);
+				return null;
+			}
+		}
+		byte[] sharedSecret;
+		try{
+			KeyAgreement keyAgreement=KeyAgreement.getInstance("ECDH");
+			keyAgreement.init(privateKey);
+			keyAgreement.doPhase(serverKey, true);
+			sharedSecret=keyAgreement.generateSecret();
+		}catch(NoSuchAlgorithmException|InvalidKeyException x){
+			Log.e(TAG, "decryptNotification: error doing key exchange", x);
+			return null;
+		}
+		byte[] secondSaltInfo="Content-Encoding: auth\0".getBytes(StandardCharsets.UTF_8);
+		byte[] key, nonce;
+		try{
+			byte[] secondSalt=deriveKey(authKey, sharedSecret, secondSaltInfo, 32);
+			byte[] keyInfo=info("aesgcm", publicKey, serverKey);
+			key=deriveKey(salt, secondSalt, keyInfo, 16);
+			byte[] nonceInfo=info("nonce", publicKey, serverKey);
+			nonce=deriveKey(salt, secondSalt, nonceInfo, 12);
+		}catch(NoSuchAlgorithmException|InvalidKeyException x){
+			Log.e(TAG, "decryptNotification: error deriving key", x);
+			return null;
+		}
+		String decryptedStr;
+		try{
+			Cipher cipher=Cipher.getInstance("AES/GCM/NoPadding");
+			SecretKeySpec aesKey=new SecretKeySpec(key, "AES");
+			GCMParameterSpec iv=new GCMParameterSpec(128, nonce);
+			cipher.init(Cipher.DECRYPT_MODE, aesKey, iv);
+			byte[] decrypted=cipher.doFinal(payload);
+			decryptedStr=new String(decrypted, 2, decrypted.length-2, StandardCharsets.UTF_8);
+			if(BuildConfig.DEBUG)
+				Log.i(TAG, "decryptNotification: notification json "+decryptedStr);
+		}catch(NoSuchAlgorithmException|NoSuchPaddingException|InvalidAlgorithmParameterException|InvalidKeyException|BadPaddingException|IllegalBlockSizeException x){
+			Log.e(TAG, "decryptNotification: error decrypting payload", x);
+			return null;
+		}
+		PushNotification notification=MastodonAPIController.gson.fromJson(decryptedStr, PushNotification.class);
+		try{
+			notification.postprocess();
+		}catch(IOException x){
+			Log.e(TAG, "decryptNotification: error verifying notification object", x);
+			return null;
+		}
+		return notification;
+	}
+
+	private byte[] deriveKey(byte[] firstSalt, byte[] secondSalt, byte[] info, int length) throws NoSuchAlgorithmException, InvalidKeyException{
+		Mac hmacContext=Mac.getInstance("HmacSHA256");
+		hmacContext.init(new SecretKeySpec(firstSalt, "HmacSHA256"));
+		byte[] hmac=hmacContext.doFinal(secondSalt);
+		hmacContext.init(new SecretKeySpec(hmac, "HmacSHA256"));
+		hmacContext.update(info);
+		byte[] result=hmacContext.doFinal(new byte[]{1});
+		return result.length<=length ? result : Arrays.copyOfRange(result, 0, length);
+	}
+
+	private byte[] info(String type, PublicKey clientPublicKey, PublicKey serverPublicKey){
+		ByteArrayOutputStream info=new ByteArrayOutputStream();
+		try{
+			info.write("Content-Encoding: ".getBytes(StandardCharsets.UTF_8));
+			info.write(type.getBytes(StandardCharsets.UTF_8));
+			info.write(0);
+			info.write("P-256".getBytes(StandardCharsets.UTF_8));
+			info.write(0);
+			info.write(0);
+			info.write(65);
+			info.write(serializeRawPublicKey(clientPublicKey));
+			info.write(0);
+			info.write(65);
+			info.write(serializeRawPublicKey(serverPublicKey));
+		}catch(IOException ignore){}
+		return info.toByteArray();
+	}
+
+	private static void registerAllAccountsForPush(){
+		for(AccountSession session:AccountSessionManager.getInstance().getLoggedInAccounts()){
+			if(TextUtils.isEmpty(session.pushServerKey))
+				session.getPushSubscriptionManager().registerAccountForPush();
+		}
+	}
+
+	public static class RegistrationReceiver extends BroadcastReceiver{
+		@Override
+		public void onReceive(Context context, Intent intent){
+			if("com.google.android.c2dm.intent.REGISTRATION".equals(intent.getAction())){
+				if(intent.hasExtra("registration_id")){
+					deviceToken=intent.getStringExtra("registration_id");
+					if(deviceToken.startsWith(KID_VALUE))
+						deviceToken=deviceToken.substring(KID_VALUE.length()+1);
+					getPrefs().edit().putString("deviceToken", deviceToken).apply();
+					Log.i(TAG, "Successfully registered for FCM");
+					registerAllAccountsForPush();
+				}else{
+					Log.e(TAG, "FCM registration intent did not contain registration_id: "+intent);
+					Bundle extras=intent.getExtras();
+					for(String key:extras.keySet()){
+						Log.i(TAG, key+" -> "+extras.get(key));
+					}
+				}
+			}
+		}
+	}
+}

mastodon/src/main/java/org/joinmastodon/android/api/requests/notifications/GetNotificationByID.java

@@ -0,0 +1,10 @@
+package org.joinmastodon.android.api.requests.notifications;
+
+import org.joinmastodon.android.api.MastodonAPIRequest;
+import org.joinmastodon.android.model.Notification;
+
+public class GetNotificationByID extends MastodonAPIRequest<Notification>{
+	public GetNotificationByID(String id){
+		super(HttpMethod.GET, "/notifications/"+id, Notification.class);
+	}
+}

mastodon/src/main/java/org/joinmastodon/android/api/requests/notifications/RegisterForPushNotifications.java

@@ -0,0 +1,35 @@
+package org.joinmastodon.android.api.requests.notifications;
+
+import org.joinmastodon.android.api.MastodonAPIRequest;
+import org.joinmastodon.android.model.PushSubscription;
+
+public class RegisterForPushNotifications extends MastodonAPIRequest<PushSubscription>{
+	public RegisterForPushNotifications(String deviceToken, String encryptionKey, String authKey, PushSubscription.Alerts alerts, String accountID){
+		super(HttpMethod.POST, "/push/subscription", PushSubscription.class);
+		Request r=new Request();
+		r.subscription.endpoint="https://app.joinmastodon.org/relay-to/fcm/"+deviceToken+"/"+accountID;
+		r.data.alerts=alerts;
+		r.subscription.keys.p256dh=encryptionKey;
+		r.subscription.keys.auth=authKey;
+		setRequestBody(r);
+	}
+
+	private static class Request{
+		public Subscription subscription=new Subscription();
+		public Data data=new Data();
+
+		private static class Keys{
+			public String p256dh;
+			public String auth;
+		}
+
+		private static class Subscription{
+			public String endpoint;
+			public Keys keys=new Keys();
+		}
+
+		private static class Data{
+			public PushSubscription.Alerts alerts;
+		}
+	}
+}

mastodon/src/main/java/org/joinmastodon/android/api/session/AccountSession.java

@@ -2,6 +2,7 @@ package org.joinmastodon.android.api.session;
 
 import org.joinmastodon.android.api.CacheController;
 import org.joinmastodon.android.api.MastodonAPIController;
+import org.joinmastodon.android.api.PushSubscriptionManager;
 import org.joinmastodon.android.api.StatusInteractionController;
 import org.joinmastodon.android.model.Account;
 import org.joinmastodon.android.model.Application;
@@ -15,9 +16,14 @@ public class AccountSession{
 	public Application app;
 	public long infoLastUpdated;
 	public boolean activated=true;
+	public String pushPrivateKey;
+	public String pushPublicKey;
+	public String pushAuthKey;
+	public String pushServerKey;
 	private transient MastodonAPIController apiController;
 	private transient StatusInteractionController statusInteractionController;
 	private transient CacheController cacheController;
+	private transient PushSubscriptionManager pushSubscriptionManager;
 
 	AccountSession(Token token, Account self, Application app, String domain, boolean activated){
 		this.token=token;
@@ -51,4 +57,10 @@ public class AccountSession{
 			cacheController=new CacheController(getID());
 		return cacheController;
 	}
+
+	public PushSubscriptionManager getPushSubscriptionManager(){
+		if(pushSubscriptionManager==null)
+			pushSubscriptionManager=new PushSubscriptionManager(getID());
+		return pushSubscriptionManager;
+	}
 }

mastodon/src/main/java/org/joinmastodon/android/api/session/AccountSessionManager.java

@@ -1,9 +1,11 @@
 package org.joinmastodon.android.api.session;
 
 import android.app.Activity;
+import android.app.NotificationManager;
 import android.content.Context;
 import android.content.SharedPreferences;
 import android.net.Uri;
+import android.os.Build;
 import android.util.Log;
 
 import com.google.gson.JsonParseException;
@@ -11,6 +13,7 @@ import com.google.gson.JsonParseException;
 import org.joinmastodon.android.MastodonApp;
 import org.joinmastodon.android.R;
 import org.joinmastodon.android.api.MastodonAPIController;
+import org.joinmastodon.android.api.PushSubscriptionManager;
 import org.joinmastodon.android.api.requests.instance.GetCustomEmojis;
 import org.joinmastodon.android.api.requests.accounts.GetOwnAccount;
 import org.joinmastodon.android.api.requests.instance.GetInstance;
@@ -92,9 +95,12 @@ public class AccountSessionManager{
 		lastActiveAccountID=session.getID();
 		writeAccountsFile();
 		maybeUpdateLocalInfo();
+		if(PushSubscriptionManager.arePushNotificationsAvailable()){
+			session.getPushSubscriptionManager().registerAccountForPush();
+		}
 	}
 
-	private void writeAccountsFile(){
+	public synchronized void writeAccountsFile(){
 		File file=new File(MastodonApp.context.getFilesDir(), "accounts.json");
 		try{
 			try(FileOutputStream out=new FileOutputStream(file)){
@@ -157,6 +163,10 @@ public class AccountSessionManager{
 		if(sessions.isEmpty() || !sessions.values().stream().map(s->s.domain.toLowerCase()).collect(Collectors.toSet()).contains(domain)){
 			getInstanceInfoFile(domain).delete();
 		}
+		if(Build.VERSION.SDK_INT>=Build.VERSION_CODES.O){
+			NotificationManager nm=MastodonApp.context.getSystemService(NotificationManager.class);
+			nm.deleteNotificationChannelGroup(id);
+		}
 	}
 
 	@NonNull
@@ -178,7 +188,7 @@ public class AccountSessionManager{
 								.appendQueryParameter("response_type", "code")
 								.appendQueryParameter("client_id", result.clientId)
 								.appendQueryParameter("redirect_uri", "mastodon-android-auth://callback")
-								.appendQueryParameter("scope", "read write follow push")
+								.appendQueryParameter("scope", SCOPE)
 								.build();
 
 						new CustomTabsIntent.Builder()

mastodon/src/main/java/org/joinmastodon/android/fragments/HomeFragment.java

@@ -1,6 +1,7 @@
 package org.joinmastodon.android.fragments;
 
 import android.app.Fragment;
+import android.app.NotificationManager;
 import android.content.res.Configuration;
 import android.graphics.Outline;
 import android.os.Build;
@@ -9,12 +10,14 @@ import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 import android.view.ViewOutlineProvider;
+import android.view.ViewTreeObserver;
 import android.view.WindowInsets;
 import android.widget.FrameLayout;
 import android.widget.ImageView;
 import android.widget.LinearLayout;
 
 import org.joinmastodon.android.MastodonApp;
+import org.joinmastodon.android.PushNotificationReceiver;
 import org.joinmastodon.android.R;
 import org.joinmastodon.android.api.session.AccountSessionManager;
 import org.joinmastodon.android.fragments.discover.DiscoverFragment;
@@ -70,6 +73,7 @@ public class HomeFragment extends AppKitFragment implements OnBackPressedListene
 		args.putBoolean("noAutoLoad", true);
 		profileFragment=new ProfileFragment();
 		profileFragment.setArguments(args);
+
 	}
 
 	@Nullable
@@ -105,6 +109,19 @@ public class HomeFragment extends AppKitFragment implements OnBackPressedListene
 					.add(R.id.fragment_wrap, notificationsFragment).hide(notificationsFragment)
 					.add(R.id.fragment_wrap, profileFragment).hide(profileFragment)
 					.commit();
+
+			String defaultTab=getArguments().getString("tab");
+			if("notifications".equals(defaultTab)){
+				tabBar.selectTab(R.id.tab_notifications);
+				fragmentContainer.getViewTreeObserver().addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener(){
+					@Override
+					public boolean onPreDraw(){
+						fragmentContainer.getViewTreeObserver().removeOnPreDrawListener(this);
+						onTabSelected(R.id.tab_notifications);
+						return true;
+					}
+				});
+			}
 		}else{
 			tabBar.selectTab(currentTab);
 		}
@@ -174,6 +191,8 @@ public class HomeFragment extends AppKitFragment implements OnBackPressedListene
 		}else if(newFragment instanceof NotificationsFragment){
 			((NotificationsFragment) newFragment).loadData();
 			// TODO make an interface?
+			NotificationManager nm=getActivity().getSystemService(NotificationManager.class);
+			nm.cancel(accountID, PushNotificationReceiver.NOTIFICATION_ID);
 		}
 		currentTab=tab;
 		((FragmentStackActivity)getActivity()).invalidateSystemBarColors(this);

mastodon/src/main/java/org/joinmastodon/android/fragments/discover/SearchFragment.java

@@ -169,6 +169,7 @@ public class SearchFragment extends BaseStatusListFragment<SearchResult>{
 	@Override
 	protected void onDataLoaded(List<SearchResult> d, boolean more){
 		super.onDataLoaded(d, more);
+		if(progressVisibilityListener!=null)
 			progressVisibilityListener.onProgressVisibilityChanged(false);
 	}
 

mastodon/src/main/java/org/joinmastodon/android/model/Notification.java

@@ -4,9 +4,11 @@ import com.google.gson.annotations.SerializedName;
 
 import org.joinmastodon.android.api.ObjectValidationException;
 import org.joinmastodon.android.api.RequiredField;
+import org.parceler.Parcel;
 
 import java.time.Instant;
 
+@Parcel
 public class Notification extends BaseModel implements DisplayItemsParent{
 	@RequiredField
 	public String id;

mastodon/src/main/java/org/joinmastodon/android/model/PushNotification.java

@@ -0,0 +1,55 @@
+package org.joinmastodon.android.model;
+
+import com.google.gson.annotations.SerializedName;
+
+import org.joinmastodon.android.R;
+import org.joinmastodon.android.api.RequiredField;
+
+import androidx.annotation.StringRes;
+
+public class PushNotification extends BaseModel{
+	public String accessToken;
+	public String preferredLocale;
+	public long notificationId;
+	@RequiredField
+	public Type notificationType;
+	@RequiredField
+	public String icon;
+	@RequiredField
+	public String title;
+	@RequiredField
+	public String body;
+
+	@Override
+	public String toString(){
+		return "PushNotification{"+
+				"accessToken='"+accessToken+'\''+
+				", preferredLocale='"+preferredLocale+'\''+
+				", notificationId="+notificationId+
+				", notificationType="+notificationType+
+				", icon='"+icon+'\''+
+				", title='"+title+'\''+
+				", body='"+body+'\''+
+				'}';
+	}
+
+	public enum Type{
+		@SerializedName("favourite")
+		FAVORITE(R.string.notification_type_favorite),
+		@SerializedName("mention")
+		MENTION(R.string.notification_type_mention),
+		@SerializedName("reblog")
+		REBLOG(R.string.notification_type_reblog),
+		@SerializedName("follow")
+		FOLLOW(R.string.notification_type_follow),
+		@SerializedName("poll")
+		POLL(R.string.notification_type_poll);
+
+		@StringRes
+		public final int localizedName;
+
+		Type(int localizedName){
+			this.localizedName=localizedName;
+		}
+	}
+}

mastodon/src/main/java/org/joinmastodon/android/model/PushSubscription.java

@@ -0,0 +1,46 @@
+package org.joinmastodon.android.model;
+
+import org.joinmastodon.android.api.AllFieldsAreRequired;
+
+@AllFieldsAreRequired
+public class PushSubscription extends BaseModel{
+	public int id;
+	public String endpoint;
+	public Alerts alerts;
+	public String serverKey;
+
+	@Override
+	public String toString(){
+		return "PushSubscription{"+
+				"id="+id+
+				", endpoint='"+endpoint+'\''+
+				", alerts="+alerts+
+				", serverKey='"+serverKey+'\''+
+				'}';
+	}
+
+	public static class Alerts{
+		public boolean follow;
+		public boolean favourite;
+		public boolean reblog;
+		public boolean mention;
+		public boolean poll;
+
+		public static Alerts ofAll(){
+			Alerts alerts=new Alerts();
+			alerts.follow=alerts.favourite=alerts.reblog=alerts.mention=alerts.poll=true;
+			return alerts;
+		}
+
+		@Override
+		public String toString(){
+			return "Alerts{"+
+					"follow="+follow+
+					", favourite="+favourite+
+					", reblog="+reblog+
+					", mention="+mention+
+					", poll="+poll+
+					'}';
+		}
+	}
+}

mastodon/src/main/java/org/joinmastodon/android/ui/utils/UiUtils.java

@@ -5,6 +5,9 @@ import android.app.Activity;
 import android.content.Context;
 import android.content.res.TypedArray;
 import android.database.Cursor;
+import android.graphics.Bitmap;
+import android.graphics.Canvas;
+import android.graphics.drawable.BitmapDrawable;
 import android.graphics.drawable.Drawable;
 import android.net.Uri;
 import android.os.Bundle;
@@ -362,4 +365,13 @@ public class UiUtils{
 		list.scrollToPosition(topItem);
 		list.scrollBy(0, topItemOffset);
 	}
+
+	public static Bitmap getBitmapFromDrawable(Drawable d){
+		if(d instanceof BitmapDrawable)
+			return ((BitmapDrawable) d).getBitmap();
+		Bitmap bitmap=Bitmap.createBitmap(d.getIntrinsicWidth(), d.getIntrinsicHeight(), Bitmap.Config.ARGB_8888);
+		d.setBounds(0, 0, d.getIntrinsicWidth(), d.getIntrinsicHeight());
+		d.draw(new Canvas(bitmap));
+		return bitmap;
+	}
 }

mastodon/src/main/res/values/strings.xml

@@ -223,4 +223,9 @@
 	<string name="recent_searches">Recent searches</string>
 	<string name="step_x_of_n">Step %1$d of %2$d</string>
 	<string name="skip">Skip</string>
+	<string name="notification_type_follow">New followers</string>
+	<string name="notification_type_favorite">Favorites</string>
+	<string name="notification_type_reblog">Boosts</string>
+	<string name="notification_type_mention">Mentions</string>
+	<string name="notification_type_poll">Polls</string>
 </resources>