Fix crashes on empty auth responses and repeated reconnects after sign-in

src/main/java/com/pusher/client/channel/impl/PrivateChannelImpl.java

@@ -81,14 +81,14 @@ public void bind(final String eventName, final SubscriptionEventListener listene
     private String authorize() {
         try {
             final AuthResponse authResponse = GSON.fromJson(getAuthorizationResponse(), AuthResponse.class);
-            channelData = authResponse.getChannelData();
-
-            if (authResponse.getAuth() == null) {
+            // Gson returns null for a null or empty response
+            if (authResponse == null || authResponse.getAuth() == null) {
                 throw new AuthorizationFailureException(
                         "Didn't receive all the fields expected " +
                                 "from the ChannelAuthorizer, expected an auth and shared_secret."
                 );
             } else {
+                channelData = authResponse.getChannelData();
                 return authResponse.getAuth();
             }
         } catch (JsonSyntaxException e) {

src/main/java/com/pusher/client/channel/impl/PrivateEncryptedChannelImpl.java

@@ -77,7 +77,8 @@ public String toSubscribeMessage() {
     private String authenticate() {
         try {
             final AuthResponse authResponse = GSON.fromJson(getAuthorizationResponse(), AuthResponse.class);
-            if (authResponse.getAuth() == null || authResponse.getSharedSecret() == null) {
+            // Gson returns null for a null or empty response
+            if (authResponse == null || authResponse.getAuth() == null || authResponse.getSharedSecret() == null) {
                 throw new AuthorizationFailureException(
                         "Didn't receive all the fields expected " +
                                 "from the ChannelAuthorizer, expected an auth and shared_secret."

src/main/java/com/pusher/client/user/impl/InternalUser.java

@@ -4,6 +4,7 @@
 import com.google.gson.JsonSyntaxException;
 import com.pusher.client.AuthenticationFailureException;
 import com.pusher.client.UserAuthenticator;
+import com.pusher.client.channel.ChannelState;
 import com.pusher.client.channel.PusherEvent;
 import com.pusher.client.channel.SubscriptionEventListener;
 import com.pusher.client.channel.impl.ChannelManager;
@@ -107,7 +108,10 @@ private AuthenticationResponse getAuthenticationResponse() throws Authentication
         String response = userAuthenticator.authenticate(connection.getSocketId());
         try {
             AuthenticationResponse authenticationResponse = GSON.fromJson(response, AuthenticationResponse.class);
-            if (authenticationResponse.getAuth() == null || authenticationResponse.getUserData() == null) {
+            // Gson returns null for a null or empty response
+            if (authenticationResponse == null
+                    || authenticationResponse.getAuth() == null
+                    || authenticationResponse.getUserData() == null) {
                 throw new AuthenticationFailureException(
                         "Didn't receive all the fields expected from the UserAuthenticator. Expected auth and user_data"
                 );
@@ -135,8 +139,11 @@ private void onSigninSuccess(PusherEvent event) {
     }
 
     private void disconnect() {
-        if (serverToUserChannel.isSubscribed()) {
+        // disconnect() runs on every CONNECTING and DISCONNECTED state change, so it
+        // can run again after userId has been cleared. getName() needs the userId.
+        if (userId != null && serverToUserChannel.isSubscribed()) {
             channelManager.unsubscribeFrom(serverToUserChannel.getName());
+            serverToUserChannel.updateState(ChannelState.UNSUBSCRIBED);
         }
         userId = null;
     }

src/test/java/com/pusher/client/channel/impl/PrivateChannelImplTest.java

@@ -123,6 +123,18 @@ public void testThrowsAuthorizationFailureExceptionIfAuthorizerReturnsBasicStrin
         channel.toSubscribeMessage();
     }
 
+    @Test(expected = AuthorizationFailureException.class)
+    public void testThrowsAuthorizationFailureExceptionIfAuthorizerReturnsNull() {
+        when(mockChannelAuthorizer.authorize(eq(getChannelName()), anyString())).thenReturn(null);
+        channel.toSubscribeMessage();
+    }
+
+    @Test(expected = AuthorizationFailureException.class)
+    public void testThrowsAuthorizationFailureExceptionIfAuthorizerReturnsEmptyString() {
+        when(mockChannelAuthorizer.authorize(eq(getChannelName()), anyString())).thenReturn("");
+        channel.toSubscribeMessage();
+    }
+
     @Test(expected = AuthorizationFailureException.class)
     public void testThrowsAuthorizationFailureExceptionIfAuthorizerReturnsInvalidJSON() {
         when(mockChannelAuthorizer.authorize(eq(getChannelName()), anyString())).thenReturn("{\"auth\":\"");

src/test/java/com/pusher/client/channel/impl/PrivateEncryptedChannelImplTest.java

@@ -169,6 +169,16 @@ public void authenticationThrowsExceptionIfNoSharedSecret() {
         channel.toSubscribeMessage();
     }
 
+    @Test(expected = AuthorizationFailureException.class)
+    public void authenticationThrowsExceptionIfAuthorizerReturnsNull() {
+        when(mockChannelAuthorizer.authorize(Matchers.anyString(), Matchers.anyString()))
+                .thenReturn(null);
+
+        PrivateEncryptedChannelImpl channel = newInstance();
+
+        channel.toSubscribeMessage();
+    }
+
     @Test(expected = AuthorizationFailureException.class)
     public void authenticationThrowsExceptionIfMalformedJson() {
         when(mockChannelAuthorizer.authorize(Matchers.anyString(), Matchers.anyString()))

src/test/java/com/pusher/client/user/impl/InternalUserTest.java

@@ -10,16 +10,20 @@
 
 import com.pusher.client.AuthenticationFailureException;
 import com.pusher.client.UserAuthenticator;
+import com.pusher.client.channel.ChannelState;
 import com.pusher.client.channel.PusherEvent;
 import com.pusher.client.channel.SubscriptionEventListener;
 import com.pusher.client.channel.impl.ChannelManager;
+import com.pusher.client.connection.ConnectionEventListener;
 import com.pusher.client.connection.ConnectionState;
+import com.pusher.client.connection.ConnectionStateChange;
 import com.pusher.client.connection.impl.InternalConnection;
 import com.pusher.client.util.Factory;
 
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
+import org.mockito.ArgumentCaptor;
 import org.mockito.Mock;
 import org.mockito.runners.MockitoJUnitRunner;
 
@@ -83,6 +87,35 @@ public void testSigninMalformedResponse() {
         user.signin();
     }
 
+    @Test(expected = AuthenticationFailureException.class)
+    public void testSigninNullResponse() {
+        when(mockConnection.getState()).thenReturn(ConnectionState.CONNECTED);
+        when(mockUserAuthenticator.authenticate(socketId)).thenReturn(null);
+        user.signin();
+    }
+
+    @Test
+    public void testRepeatedReconnectsAfterSigninDoNotThrow() {
+        final ArgumentCaptor<ConnectionEventListener> connectionListener =
+                ArgumentCaptor.forClass(ConnectionEventListener.class);
+        verify(mockConnection).bind(eq(ConnectionState.ALL), connectionListener.capture());
+
+        user.handleEvent(PusherEvent.fromJson(signinSuccessEvent));
+        final ArgumentCaptor<ServerToUserChannel> serverToUserChannel =
+                ArgumentCaptor.forClass(ServerToUserChannel.class);
+        verify(mockChannelManager).subscribeTo(serverToUserChannel.capture(), eq(null));
+        serverToUserChannel.getValue().updateState(ChannelState.SUBSCRIBED);
+
+        // Each reconnect attempt moves the connection through CONNECTING again
+        connectionListener.getValue()
+                .onConnectionStateChange(new ConnectionStateChange(ConnectionState.RECONNECTING, ConnectionState.CONNECTING));
+        connectionListener.getValue()
+                .onConnectionStateChange(new ConnectionStateChange(ConnectionState.RECONNECTING, ConnectionState.CONNECTING));
+
+        verify(mockChannelManager).unsubscribeFrom("#server-to-user-1");
+        assertNull(user.userId());
+    }
+
     @Test
     public void testHandleEventSigninSuccessEvent() {
         user.handleEvent(PusherEvent.fromJson(signinSuccessEvent));