panic: index out of range in getBytesAndSize on empty event payload (StreamReplaced) crashes process

[rbinar]

Summary

getBytesAndSize panics with index out of range [0] with length 0 and crashes the whole process (SIGABRT) when an event's marshaled payload is empty. Reproducibly triggered by a StreamReplaced event.

Version

neonize 0.3.18.post0 (latest), Linux x86_64, Python 3.12.

Traceback (from production)

INFO  Successfully authenticated
INFO  Got replaced stream error, sending StreamReplaced event
panic: runtime error: index out of range [0] with length 0

goroutine 18 [running, locked to thread]:
main.getBytesAndSize(...)
	/home/runner/work/neonize/neonize/goneonize/main.go:341
main.CallbackFunction({...}, ...)
	/home/runner/work/neonize/neonize/goneonize/main.go:2444 +0x1eb
main.Neonize(...)
	/home/runner/work/neonize/neonize/goneonize/main.go:1092 +0xad5

Root cause

getBytesAndSize (goneonize/main.go:340-344) dereferences &data[0]:

func getBytesAndSize(data []byte) (*C.char, C.size_t) {
	messageSourceCDATA := (*C.char)(unsafe.Pointer(&data[0]))  // panics when len(data)==0
	messageSourceCSize := C.size_t(len(data))
	return messageSourceCDATA, messageSourceCSize
}

CallbackFunction (main.go:2444) calls it with proto.Marshal(message.message). For some events (observed: StreamReplaced) the marshaled message is empty (0 bytes), so &data[0] panics and aborts the runtime — taking down the entire host process.

Impact

Any session that receives a StreamReplaced event (e.g. the same account's stream is taken over by another client) crashes the process. Under supervisor/systemd this becomes a crash-restart loop (reconnect → StreamReplaced → panic → restart → …), making the service unusable and blocking new QR pairings.

Proposed fix

Guard getBytesAndSize against empty input:

func getBytesAndSize(data []byte) (*C.char, C.size_t) {
	if len(data) == 0 {
		return nil, 0
	}
	messageSourceCDATA := (*C.char)(unsafe.Pointer(&data[0]))
	messageSourceCSize := C.size_t(len(data))
	return messageSourceCDATA, messageSourceCSize
}

(The C side already receives an explicit size, so a nil/0 pair for empty payloads is safe.)