Phone calls can trigger immediate crash

[cohoe]

I was trying to simulate starting a KrakenTalk phone call with a Javascript script by opening a websocket to the endpoint https://beta.twitarr.com/api/v3/phone/socket/initiate/DCB94249-4562-493D-964C-C3E733FBD5D3/to/46E2B505-FA66-4A4C-80EF-3BF5D253579F. The callID DCB94249-4562-493D-964C-C3E733FBD5D3 is a random UUID I generated. The userID 46E2B505-FA66-4A4C-80EF-3BF5D253579F is the sam user.

If Sam doesn't have a notification socket open (like if it's only logged in via the browser) then the app basically does nothing which is expected and produces the following logs:

[ INFO ] GET /api/v3/phone/socket/initiate/DCB94249-4562-493D-964C-C3E733FBD5D3/to/46E2B505-FA66-4A4C-80EF-3BF5D253579F -> 101 Switching Protocols [request-id: A73EACD1-186D-4825-B3CB-C24FC1D43EDB]
[ NOTICE ] Attempt to call user with no notification socket. [request-id: A73EACD1-186D-4825-B3CB-C24FC1D43EDB]

But if Sam is logged in via Tricordarr which opens a notification socket and the same call is made, the app immediately crashes:

[ INFO ] GET /api/v3/phone/socket/initiate/DCB94249-4562-493D-964C-C3E733FBD5D3/to/46E2B505-FA66-4A4C-80EF-3BF5D253579F -> 101 Switching Protocols [request-id: 03E58630-D14C-4AAD-A90C-BF8AC441B2DC]
[ NOTICE ] Creating phone socket. [request-id: 03E58630-D14C-4AAD-A90C-BF8AC441B2DC]
[ NOTICE ] Sending incoming phonecall to callee. [request-id: 03E58630-D14C-4AAD-A90C-BF8AC441B2DC]
[ NOTICE ] Sending incoming phonecall to callee. [request-id: 03E58630-D14C-4AAD-A90C-BF8AC441B2DC]
Received signal 4. Backtrace:
[ INFO ] GET /api/v3/notification/global -> 200 OK [request-id: 50B32616-134E-4603-A527-8E104788A120]
0x55c43126bdf2, Backtrace.(printBacktrace in _B82A8C0ED7C904841114FDF244F9E58E)(signal: Swift.Int32) -> () at /app/.build/checkouts/swift-backtrace/Sources/Backtrace/Backtrace.swift:80
0x55c43126c067, closure #1 (Swift.Int32) -> () in static Backtrace.Backtrace.install(signals: Swift.Array<Swift.Int32>) -> () at /app/.build/checkouts/swift-backtrace/Sources/Backtrace/Backtrace.swift:94
0x55c43126c067, @objc closure #1 (Swift.Int32) -> () in static Backtrace.Backtrace.install(signals: Swift.Array<Swift.Int32>) -> () at /app/<compiler-generated>:93
0x7fd2dc75751f
0x55c431c76310, Swift runtime failure: precondition failure at /app/<compiler-generated>:0
0x55c431c76310, function signature specialization <Arg[0] = Dead, Arg[1] = Dead> of (extension in NIOCore):NIOCore.EventLoop.preconditionInEventLoop(file: Swift.StaticString, line: Swift.UInt) -> () at /app/<compiler-generated>:0
0x55c431c76310, (extension in NIOCore):NIOCore.EventLoop.preconditionInEventLoop(file: Swift.StaticString, line: Swift.UInt) -> () at /app/<compiler-generated>:0
0x55c431c76310, generic specialization <@Sendable (WebSocketKit.WebSocket, NIOCore.ByteBuffer) -> ()> of NIOCore.NIOLoopBoundBox.value.setter : A at /app/<compiler-generated>:0
0x55c431c76310, WebSocketKit.WebSocket.onBinary((WebSocketKit.WebSocket, NIOCore.ByteBuffer) -> ()) -> () at /app/.build/checkouts/websocket-kit/Sources/WebSocketKit/WebSocket.swift:66
0x55c431e1bf81, (4) suspend resume partial function for swiftarr.PhonecallController.createPhoneSocket(Vapor.Request, WebSocketKit.WebSocket) async -> () at /app/Sources/swiftarr/Controllers/PhonecallController.swift:274
0x7fd2dd2a50cd
0x7fd2dd2a589b
0x7fd2ddde6773
0x7fd2ddde6521
0x7fd2dddf2001
0x7fd2dc7a9ac2
0x7fd2dc83a813
0xffffffffffffffff

The Android app reported a socket message came through matching what we expect, so whatever issue here is happening immediately after the call notification goes through.

I was able to reproduce this in the Beta, my personal instance, and locally. Analyzing the coredump yields:

* thread #1, name = 'swiftarr', stop reason = signal SIGILL: illegal operand
  * frame #0: 0x000056135ea49310 swiftarr`$s12WebSocketKit0aB0C8onBinaryyyyAC_7NIOCore10ByteBufferVtcF at <compiler-generated>:0
    frame #1: 0x000056135ebeef82 swiftarr`$s8swiftarr19PhonecallControllerV17createPhoneSocketyy5Vapor7RequestC_03WebF3Kit0iF0CtYaFTY3_ at PhonecallController.swift:274:6
    frame #2: 0x00007f321b3900ce

[cohoe]

I thought maybe this was being triggered by having multiple NotificationSockets open. But it still died even when I had only one (logged the calleeNotificationSockets.count to be sure).

[cohoe]

Oh. Pretty sure it's vapor/websocket-kit#140

[cohoe]

Workaround described in vapor/websocket-kit#140 seems to be functioning!