JavaScript strings with NULL character are not handled properly when passed to Native Modules

[Nick Spacek]

Description

We are using STOMP over WebSockets to communicate with our API. On iOS everything is working as expected, on Android messages are not arriving intact. As we dug it, we discovered the trailing NULL (\0) character in the strings was not arriving.

As we sought to narrow down the cause we were able to confirm (using a sample Native Module based on the ToastAndroid module) that on Android a JavaScript string containing any NULL characters is not processed as expected; when the parameter arrives in the Java code, it has been truncated to the first occurrence of the NULL character, and the NULL character is also dropped.

For example "Hello World\0" arrives as "Hello World". "Hello\0World\0" arrives as "Hello".

Because the STOMP protocol is expecting a NULL-terminated string, it discards the WebSocket message as invalid.

Reproduction

Managed to reproduce in a fairly straightforward manner here: https://rnplay.org/apps/tkNMOQ

On Android, the element shows "Hello", presumably because the ws.send('Hello\0World\0') has been truncated. On iOS, the element shows "HelloWorld"

Solution

I'd love to understand where things are being translated from JavaScript to Java in React Native, and did start digging a bit. Ideally, NULL characters are escaped/allowed to be passed through to the Java side of things untouched, as they are on iOS.

Additional Information

• React Native version: 0.42
• Platform: Android
• Operating System: Linux

[Janic Duplessis]

Could it be because the c++ bridge uses NULL terminated strings?

cc @mhorowitz

[Tkk]

we have the same proble, did you resolve it? @nickspacek

[Tkk]

if you are use spring websocket, you can try this

public void handleMessage(WebSocketSession session, WebSocketMessage<?> message) throws Exception {
        if (message instanceof TextMessage) {
            TextMessage msg = (TextMessage) message;
            String payload = msg.getPayload();
            message = new TextMessage(payload + "\u0000");
        }
        super.handleMessage(session, message);
    }

[stale]

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