I think this closes the loop on DNS issues I was experiencing.
Previously, after starting Nebula, DNS would work until you switched
networks (e.g. from mobile to WiFi or vice-versa). This was fixed by
removing some explicit DNS server sets in commit
a283bf8010. This casued DNS to work in
`adb shell` even after toggling networks.
However, it did not actually fix the problem for Android applications.
The new behavior is that they would work while on WiFi, but fail on a
mobile network.
To quote Android docs:
> Allows traffic from the specified address family. By default, if no
> address, route or DNS server of a specific family (IPv4 or IPv6) is
> added to this VPN, then all outgoing traffic of that family is blocked.
> If any address, route or DNS server is added, that family is allowed.
> This method allows an address family to be unblocked even without adding
> an address, route or DNS server of that family. Traffic of that family
> will then typically fall-through to the underlying network if it's
> supported. family must be either AF_INET (for IPv4) or AF_INET6 (for
> IPv6). IllegalArgumentException is thrown if it's neither.
In my case, my home network supports only IPv4 while my mobile network
uses DNS over IPv6. Since my Nebula routes are IPv4-only, IPv6 traffic
stopped working, and DNS requests failed.
Previously when `stopVpn()` was called, it was possible for the network
change callback to fire while we were in the middle of shutting down.
This commit unregisters the network change callback before telling
Nebula to shutdown.
Fixes#15. When tapping the toggle in rapid succession,
`NebulaVpnService.onStartCommand` is called twice, in serial. This
method includes logic to show an error to the user if they somehow
attempt to connect to a service while already connected.
However, this method of showing an error message (calling
`announceExit`) sends a signal to `MainActivity` telling it the service
has exited, and that it should set the UI state to "Disconnected." It
does not actually disconnect the service at this point, resulting in a
state mismatch in which you cannot actually disconnect the service.
The solution in this commit is to remove this signalling and simply
return out of `onStartCommand` to avoid processing the start request
twice if the site is already running.
John Maguire
Nate Brown