ProfileService: Rework profile updating

This should help discourage editing a Profile without making a copy
first, since the caller has to keep track of the old Profile as well.

ProfileAdder has been updated to prevent adding duplicate profiles. It
checks once in the constructor, so the caller can catch the exception
and pass the error back to the UI. It checks again in the worker thread
to prevent any race from happening if a profile is added twice quickly.
Either the file exists, or it doesn't.

Additionally, this change solves the race condition when the old
profile is removed before it is updated; previously this would lead
to the profile being re-added. Now, ProfileRemover will fail and the
profile will stay removed.

Finally, updating a profile's name should now work correctly. There were
previously multiple bugs with that (the old profile wasn't removed, the
new one could duplicate a name, the new one could overwrite some random
other one, etc.).

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

app/src/main/java/com/wireguard/android/ProfileService.java

@@ -54,10 +54,15 @@ public class ProfileService extends Service {
 
     private class ProfileAdder extends AsyncTask<Void, Void, Boolean> {
         private final Profile profile;
+        private final boolean shouldConnect;
 
-        private ProfileAdder(Profile profile) {
+        private ProfileAdder(Profile profile, boolean shouldConnect) {
             super();
+            for (Profile p : profiles)
+                if (p.getName().equals(profile.getName()))
+                    throw new IllegalStateException("Profile already exists: " + profile.getName());
             this.profile = profile;
+            this.shouldConnect = shouldConnect;
         }
 
         @Override
@@ -65,6 +70,8 @@ public class ProfileService extends Service {
             Log.i(TAG, "Adding profile " + profile.getName());
             try {
                 final String configFile = profile.getName() + ".conf";
+                if (new File(getFilesDir(), configFile).exists())
+                    throw new IOException("Refusing to overwrite existing profile configuration");
                 final FileOutputStream stream = openFileOutput(configFile, MODE_PRIVATE);
                 stream.write(profile.toString().getBytes(StandardCharsets.UTF_8));
                 stream.close();
@@ -81,6 +88,8 @@ public class ProfileService extends Service {
                 return;
             profile.setIsConnected(false);
             profiles.add(profile);
+            if (shouldConnect)
+                new ProfileConnecter(profile).execute();
         }
     }
 
@@ -173,10 +182,14 @@ public class ProfileService extends Service {
 
     private class ProfileRemover extends AsyncTask<Void, Void, Boolean> {
         private final Profile profile;
+        private final Profile replaceWith;
+        private final boolean shouldConnect;
 
-        private ProfileRemover(Profile profile) {
+        private ProfileRemover(Profile profile, Profile replaceWith, Boolean shouldConnect) {
             super();
             this.profile = profile;
+            this.replaceWith = replaceWith;
+            this.shouldConnect = shouldConnect != null ? shouldConnect : false;
         }
 
         @Override
@@ -196,46 +209,8 @@ public class ProfileService extends Service {
             if (!result)
                 return;
             profiles.remove(profile);
-        }
-    }
-
-    private class ProfileUpdater extends AsyncTask<Void, Void, Boolean> {
-        private final Profile profile, newProfile;
-        private final boolean wasConnected;
-
-        private ProfileUpdater(Profile profile, Profile newProfile, boolean wasConnected) {
-            super();
-            this.profile = profile;
-            this.newProfile = newProfile;
-            this.wasConnected = wasConnected;
-        }
-
-        @Override
-        protected Boolean doInBackground(Void... voids) {
-            Log.i(TAG, "Updating profile " + profile.getName());
-            if (!newProfile.getName().equals(profile.getName()))
-                throw new IllegalStateException("Profile name mismatch: " + profile.getName());
-            try {
-                final String configFile = profile.getName() + ".conf";
-                final FileOutputStream stream = openFileOutput(configFile, MODE_PRIVATE);
-                stream.write(newProfile.toString().getBytes(StandardCharsets.UTF_8));
-                stream.close();
-                return true;
-            } catch (IOException e) {
-                Log.e(TAG, "Could not update profile " + profile.getName(), e);
-                return false;
-            }
-        }
-
-        @Override
-        protected void onPostExecute(Boolean result) {
-            if (!result)
-                return;
-            // FIXME: This is also why the list of profiles should be a map.
-            final int index = profiles.indexOf(profile);
-            profiles.set(index, newProfile);
-            if (wasConnected)
-                new ProfileConnecter(newProfile).execute();
+            if (replaceWith != null)
+                new ProfileAdder(replaceWith, shouldConnect).execute();
         }
     }
 
@@ -276,23 +251,20 @@ public class ProfileService extends Service {
                 return;
             if (profile.getIsConnected())
                 new ProfileDisconnecter(profile).execute();
-            new ProfileRemover(profile).execute();
+            new ProfileRemover(profile, null, null).execute();
         }
 
         @Override
-        public void saveProfile(Profile newProfile) {
-            // FIXME: This is why the list of profiles should be a map.
-            Profile profile = null;
-            for (Profile p : profiles)
-                if (p.getName().equals(newProfile.getName()))
-                    profile = p;
-            if (profile != null) {
-                final boolean wasConnected = profile.getIsConnected();
+        public void saveProfile(Profile oldProfile, Profile newProfile) {
+            if (oldProfile != null) {
+                if (!profiles.contains(oldProfile))
+                    return;
+                final boolean wasConnected = oldProfile.getIsConnected();
                 if (wasConnected)
-                    new ProfileDisconnecter(profile).execute();
-                new ProfileUpdater(profile, newProfile, wasConnected).execute();
+                    new ProfileDisconnecter(oldProfile).execute();
+                new ProfileRemover(oldProfile, newProfile, wasConnected).execute();
             } else {
-                new ProfileAdder(newProfile).execute();
+                new ProfileAdder(newProfile, false).execute();
             }
         }
     }

app/src/main/java/com/wireguard/android/ProfileServiceInterface.java

@@ -57,13 +57,14 @@ public interface ProfileServiceInterface {
     void removeProfile(Profile profile);
 
     /**
-     * Adds the profile if it does not yet exist, or replaces an existing profile of the same name.
+     * Replace the given profile, or add a new profile if oldProfile is null.
      * If the profile exists and is currently connected, it will be disconnected before the
      * replacement, and the service will attempt to reconnect it afterward. If the profile is new,
      * it will be set to the disconnected state. If successful, configuration for this profile will
      * be saved to persistent storage.
      *
+     * @param oldProfile The existing profile to replace, or null to add the new profile.
      * @param newProfile The profile to add, or a copy of the profile to replace.
      */
-    void saveProfile(Profile newProfile);
+    void saveProfile(Profile oldProfile, Profile newProfile);
 }