Krzysztof Magiera
d16531e8a4
Summary: This change removes Content-Length header from proxy inspector response. The presence of this header was resulting in the response being cropped under some circumstances because of erroneously calculated length. The `Content-Length` header value represents the number of bytes in the response. In the code, `string.length` was used to calculate that value, but in JavaScript it gives the number of characters in a string instead of its size in bytes. Specifically, if there are some UTF characters in the string that occupy more than byte, there would be a mismatch in this size. This mismatch resulted in the response being cropped. The easiest way to reproduce this problem is to set the simulator name to contain a two-byte UTF character. This change works according to the HTTP spec, which states that when Content-Length is not present, the end of the response stream indicates the end of the response. Since in the code `response.end(data)` is use, it terminates the stream and hence there is no need to provide the length in the header. ## Changelog: [GENERAL] [FIXED] - fix issue with debugger not working when device name contain two-byte UTF characters Pull Request resolved: https://github.com/facebook/react-native/pull/42590 Test Plan: 1. Change your iOS simulator name to contain some two-byte UTF character (for example this one: "–") 2. Run metro and connect your app with it 3. Go to http://localhost:8081/json/list in your browser – see the response being marked invalid as it is cropped 4. Apply the change and see that the resulting JSON in the response is now correct 5. Open debugger workflow to confirm it sees the connected device Reviewed By: robhogan Differential Revision: D52958725 Pulled By: motiz88 fbshipit-source-id: 92c32893cbbf8552237585d824e4a44737fa3968
@react-native/dev-middleware
Dev server middleware supporting core React Native development features. This package is preconfigured in all React Native projects.
Usage
Middleware can be attached to a dev server (e.g. Metro) using the createDevMiddleware API.
import { createDevMiddleware } from '@react-native/dev-middleware';
function myDevServerImpl(args) {
...
const {middleware, websocketEndpoints} = createDevMiddleware({
projectRoot: metroConfig.projectRoot,
serverBaseUrl: `http://${args.host}:${args.port}`,
logger,
});
await Metro.runServer(metroConfig, {
host: args.host,
...,
unstable_extraMiddleware: [
middleware,
// Optionally extend with additional HTTP middleware
],
websocketEndpoints: {
...websocketEndpoints,
// Optionally extend with additional WebSocket endpoints
},
});
}
Included middleware
@react-native/dev-middleware is designed for integrators such as @expo/dev-server and @react-native/community-cli-plugin. It provides a common default implementation for core React Native dev server responsibilities.
We intend to keep this to a narrow set of functionality, based around:
- Debugging — The Chrome DevTools protocol (CDP) endpoints supported by React Native, including the Inspector Proxy, which facilitates connections with multiple devices.
- Dev actions — Endpoints implementing core Dev Menu actions, e.g. reloading the app, opening the debugger frontend.
HTTP endpoints
DevMiddlewareAPI.middleware
These are exposed as a connect middleware handler, assignable to Metro.runServer or other compatible HTTP servers.
GET /json/list, /json (CDP)
Returns the list of available WebSocket targets for all connected React Native app sessions.
GET /json/version (CDP)
Returns version metadata used by Chrome DevTools.
GET /debugger-frontend
Subpaths of this endpoint are reserved to serve the JavaScript debugger frontend.
POST /open-debugger
Open the JavaScript debugger for a given CDP target (direct Hermes debugging).
Example
curl -X POST 'http://localhost:8081/open-debugger?appId=com.meta.RNTester'
WebSocket endpoints
DevMiddlewareAPI.websocketEndpoints
/inspector/device
WebSocket handler for registering device connections.
/inspector/debug
WebSocket handler that proxies CDP messages to/from the corresponding device.
Contributing
Changes to this package can be made locally and tested against the rn-tester app, per the Contributing guide. During development, this package is automatically run from source with no build step.