uNetworking / uNetworking/uWebSockets.js

setYield(true) in last handler does not trigger 404 response

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enhancement
Dominant language
C++
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Merged PRs (30d)
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Description

version: v20.51.0
platform: Microsoft Windows NT 10.0.19045.0 x64

calling setYield breaks default handler
i can assume it is a bug or undocumented behavior
in both cases fix is required

example:

import { App } from "uWebSockets.js";

const app = App();
app.listen(8080, function(token) {
    if (!token) console.error(`Failed to start listening`)
})

request to example above results in the following response

> GET / HTTP/1.1
> Host: localhost:8080
> Accept: */*

< HTTP/1.1 404 File Not Found
< Date: Mon, 21 Apr 2025 13:28:41 GMT
< uWebSockets: 20
< Content-Length: 81

with body

<html><body><h1>File Not Found</h1><hr><i>uWebSockets/20 Server</i></body></html>

but when any listener that just yields attached

import { App } from "uWebSockets.js";

const app = App();
app.any("/*", function(res, req) {
    console.log(req.getMethod(), req.getUrl());
    req.setYield(true);
});
app.listen(8080, function(token) {
    if (!token) console.error(`Failed to start listening`)
})

same request fails

> GET / HTTP/1.1
> Host: localhost:8080
> Accept: */*

* Empty reply from server
* Closing connection 60

problem can be solved with attachment of explicit default handler

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  4. Open a pull request that references the issue number.

Research direction

Reproduce the two uWebSockets.js App examples on Windows with v20.51.0, comparing the default 404 response with the app.any("/*") handler that calls req.setYield(true). Trace how setYield interacts with the default handler and verify that an unmatched request still receives the expected 404 response rather than an empty reply.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp, javascript, nodejs
Domain
api, backend
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
42/100

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