WebSocket.ping() on Android sends an empty binary frame instead of a protocol-level PING

Description

WebSocket.ping() on Android sends an empty binary data frame (opcode 0x2) via OkHttp's
client.send(ByteString.EMPTY), instead of a real RFC 6455 PING control frame (opcode 0x9). On iOS,
ping() correctly sends a protocol-level ping via SocketRocket's sendPing:error:.

This breaks against WebSocket servers that reject binary frames (e.g. AWS API Gateway WebSocket APIs),
which close the connection with code 1003 UNSUPPORTED_DATA instead of responding with a pong.

The incorrect ping() that sends the empty frame is still present on the latest version (v0.86.2) of RN here: https://github.com/react/react-native/blob/v0.86.2/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/modules/websocket/WebSocketModule.kt#L327

    try {
      client.send(ByteString.EMPTY)
    } catch (e: Exception) {
      notifyWebSocketFailed(id, e.message)
    }

Steps to reproduce

1. Connect a WebSocket to a server that rejects binary frames (e.g. AWS API Gateway WS API).
2. Call webSocket.ping() on Android.
3. Observe the connection closes with 1003 UNSUPPORTED_DATA instead of receiving a pong.

React Native Version

0.86.2

Affected Platforms

Runtime - Android

Output of npx @react-native-community/cli info

System:
  OS: macOS 26.5.2
  CPU: (12) arm64 Apple M4 Pro
  Memory: 106.66 MB / 24.00 GB
  Shell:
    version: "5.9"
    path: /opt/homebrew/bin/zsh
Binaries:
  Node:
    version: 23.10.0
    path: /opt/homebrew/bin/node
  Yarn:
    version: 1.22.19
    path: /opt/homebrew/bin/yarn
  npm:
    version: 10.9.2
    path: /opt/homebrew/bin/npm
  Watchman:
    version: 2025.05.19.00
    path: /opt/homebrew/bin/watchman
Managers:
  CocoaPods: Not Found
SDKs:
  iOS SDK:
    Platforms:
      - DriverKit 25.2
      - iOS 26.2
      - macOS 26.2
      - tvOS 26.2
      - visionOS 26.2
      - watchOS 26.2
  Android SDK: Not Found
IDEs:
  Android Studio: 2024.2 AI-242.23726.103.2422.12816248
  Xcode:
    version: 26.2/17C52
    path: /usr/bin/xcodebuild
Languages:
  Java:
    version: 17.0.14
    path: /Users/inging/.jenv/shims/javac
  Ruby: Not Found
npmPackages:
  "@react-native-community/cli": Not Found
  react: Not Found
  react-native: Not Found
  react-native-macos: Not Found
npmGlobalPackages:
  "*react-native*": Not Found
Android:
  hermesEnabled: Not found
  newArchEnabled: Not found
iOS:
  hermesEnabled: Not found
  newArchEnabled: Not found

Stacktrace or Logs

Logs from mitmproxy with a custom interceptor script:


<IP_REDACTED>:44604 -> WebSocket binary message -> <WSS_HOST_REDACTED>:443/
Error in WebSocket connection to <WSS_HOST_REDACTED>:443: WebSocket Error: UNSUPPORTED_DATA (reason: Binary is not supported)

MANDATORY Reproducer

https://gist.github.com/dekpient/4b611eb4efb58ecc1a881942f842a595

Screenshots and Videos

No response

Start at ReactAndroid/src/main/java/com/facebook/react/modules/websocket/WebSocketModule.kt around line 327 and compare the Android path with iOS's SocketRocket sendPing:error:. Use the mandatory reproducer against a server that rejects binary frames; done means Android emits an RFC 6455 PING (opcode 0x9) and no longer closes with 1003 UNSUPPORTED_DATA.