ZeroTier Android app work report

Brenton Bostick

Mon Feb 27 2023

Overview

I started looking at the ZeroTier Android app when I joined in November 2022.

First items of work were fixing the many warnings when building Android app and ZeroTierOne itself.

There were crashes triggered by simply putting the device into landscape:

The landscape crash is about 20% of all reported events.

There were also crashes triggered by simply “playing around” with the app.

I believe the underlying cause of the toggle spamming is about another 20% of all reported events.

Looking at the code, there are TONS of warnings and lints in Android Studio.

Very low-hanging fruit to fix.

I have spent the last several weeks and months working on an update to the ZeroTier Android app and I believe it is in a good state.

What did I change?

The code is on branches in 2 repos:
https://github.com/zerotier/ZeroTierOne/tree/brenton/main
https://github.com/zerotier/ZeroTierAndroid/tree/brenton/main

I tried to maintain original style of code as much as possible and take a very conservative approach.
This is not a rewrite.

That being said, there are a lot of commits.

Redesigned the screens

old Network List screen and new Network List screen:

old Network Details screen and new Network Details screen:

old Add Network screen and new Add Network screen:

old Settings screen and new Settings screen:

Redesigned the icons

old icon and new icon:

Added splashscreen

Fixed all of the bugs I found

Fixed all of the lints I found

Added massive amount of error handling

Report unhandled pending exceptions in JNI callbacks.

Because java bytes, shorts, ints, and longs are signed, added protections for exceeding JSIZE_MAX in JNI code when going between signed and unsigned and in various constructors.

Lookup all jclass and jmethod once and cache

old way did a lot of unnecessary work constantly

Fixed bugs

ANDROID-0: multiple problems with building Android

ANDROID-1: last network cannot be removed

ANDROID-6: never updates to ONLINE

ANDROID-10: Notification not showing

ANDROID-11: eventBus was not registering on resume

ANDROID-17: bitwise operators in conditional statements

ANDROID-18: AddressType is always IPV6

ANDROID-30: bad byte comparisons in isIPv6Multicast

ANDROID-31: straighten out usage of NetworkConfig useCustomDNS

ANDROID-33: double-checked locking in greenDAO stuff

ANDROID-34: Thread safety

ANDROID-35: memory leak

ANDROID-36: ResultCode.java issues

ANDROID-37: VirtualNetworkStatus out-of-sync with ZT_VirtualNetworkStatus enum

ANDROID-38: stack corruption in onSendPacketRequested

ANDROID-39: NetworkType out-of-sync with VirtualNetworkType

ANDROID-40: VirtualNetworkConfigOperation out-of-sync with ZT_VirtualNetworkConfigOperation enum

ANDROID-41: still shows as connected after canceling VPN dialog

ANDROID-42: copy/paste error in VirtualNetworkConfig.java

ANDROID-44: Multiple NetworkList activities getting stacked

ANDROID-46: re-opening app does not show connected network

ANDROID-49: fix VirtualNetworkConfig.equals

ANDROID-50: RESULT_ERROR_BAD_PARAMETER typo

ANDROID-51: fieldName is uninitialized

ANDROID-52: synchronization bug with nodeMap

Other finished items

ANDROID-2: add splash screen

ANDROID-3: update icons

ANDROID-8: DNS work

ANDROID-13: OnBackInvokedCallback is not enabled for the application

ANDROID-21: redesign Join Network screen

ANDROID-22: redesign Network Details screen

ANDROID-23: redesign Network List screen

ANDROID-24: add view for when there are no networks yet

ANDROID-25: all string resources should be organized

ANDROID-29: Touch target size too small

ANDROID-32: remove Context.BIND_DEBUG_UNBIND

ANDROID-43: Big Database changes

ANDROID-45: Settings screen work

ANDROID-47: remove SQLCipher

ANDROID-48: cache field and method lookups

Known issues / loose ends / livewires

Try to quantify all known problems.

The toggle switches now feel “heavy” when toggling

There is now work being done when the switch toggles.

ONLINE being displayed, even when there is a problem

Should only set ONLINE when actually online.

ZeroTierOneService

All of the service binding / unbinding logic is not completely understood.

In logs:

stopSelfResult() failed!
stopService() returned false

~2 minute delay

The ~2 minute delay in disconnecting from VPN and then onDestroy() actually getting called.

onUnbind is called immediately, but then ~2 minutes later onDestroy is called and then service is actually destroyed.

Airplane mode

Currently, there is nothing to show that there is no network connectivity, just keeps going with no feedback

sending does fail, but this gets ignored in viaPath->send in Switch.cpp.

and is ignored in:

IncomingPacket.cpp
_doECHO
_path->send