I noticed NDAClose() (by way of NDAInit) was sometimes trying to close an invalid window. It turns out that the compiler-generated glue code calls ~DAID before calling your NDAInit. When starting up, it generates a new User ID for mallocs. When shutting down, it disposes that ID (effectively free()-ing everything that's been malloced). This happens before NDAInit is called.

The main issue though is that NDAInit(0) can be called multiple times without an intervening NDAInit($ffff) and the globals variable isn't nulled out unless globals->ndaActive is true, so there's dangling memory. If someone else happens to NewHandle it and starts writing data into it, NDAInit()/NDAClose() will try to close something that isn't a window which can crash hard.

https://github.com/byteworksinc/SysLib/blob/4ff5bdbc7ceb0f46e6756d2dd4f3efc730de4f1b/cd.asm#L506-L571

https://github.com/jeremysrand/Listener/blob/0071f3d4ebfe11e4dc347b3bb7c070842e5aa957/Listener/main.c#L237C1-L254C2

If you use Listener in Spectrum's editor window, only some of the keystrokes generated by the NDA seem to reach the application. For example, if the app hears:

This is a test of listener

Then, you might see this inserted into the Spectrum editor.

Thss aet fltner

I have already added code to try to pace the rate at which the NDA inserts keystrokes. The NDA now will only insert a keystroke event if there are no other keystroke events on the queue. But even with that, keystrokes are getting lost.

This is a report from a beta tester:

Two things I noticed so far bug wise: 1) If the device goes to sleep or otherwise looses the connection, the GS still thinks it’s connected. Closing the NDA and reoppening it still thinks it is connected, and reconnecting from the iOS app does not result in anything showing up on the GS. 2) When issue #1 happens, I tried closing the NDA, then disconnecting the network connection on the GS with the TCP/IP control panel, then reconnecting. Opening the NDA after that results in “Unable to get connection state Error code = $3601”

My plan is to have the app actively disconnect before the device goes to sleep but this report also indicates that the NDA isn't handling non-normal disconnection well. This needs to be investigated to make the NDA more resilient to network funkiness.