req.setDataHandler callback never fires on b96 — every POST to SetHttpHandler hangs

[ktox-dev]

Summary

On FiveM for GTAV Enhanced (FXServer b96), the callback passed to
req.setDataHandler(...) inside a SetHttpHandler handler is never invoked.
The handler therefore never sends a response and the connection is closed by
the server after ~5 seconds with no reply.

The same resource works correctly on FiveM Legacy.

Reproduction

A minimal server-only resource:

-- fxmanifest.lua
fx_version 'cerulean'
game 'common'
server_script 'server.lua'

-- server.lua
SetHttpHandler(function(req, res)
    if req.method == 'POST' then
        req.setDataHandler(function(body)
            -- never reached on b96
            res.writeHead(200, { ['Content-Type'] = 'application/json' })
            res.send('{"ok":true}')
        end)
        return
    end

    res.writeHead(200, { ['Content-Type'] = 'application/json' })
    res.send('{"get":true}')
end)

# works
curl -i http://localhost:30120/<resource>/anything

# hangs, then the connection is closed with no response
curl -i -X POST -H "Content-Type: application/json" \
     -d '{"a":1}' http://localhost:30120/<resource>/anything

Expected vs actual

Expected: the POST returns 200 {"ok":true}.

Actual: no response at all. curl reports status 000 after ~5.2 s.

Isolation

The request/response path itself is fine — only the body callback is affected.
Measured against a real resource with both GET and POST routes:

Request	Result
GET, known route (responds directly)	200 in 0.22 s
POST, unknown route (responds 404 without reading the body)	404 in 0.22 s
POST, known route (calls req.setDataHandler)	no response, connection closed after 5.2 s

The second row is the interesting one: it takes the same code path — accept
request, check req.method, look up the route — and answers immediately. The
only difference in the third row is that the handler reads the request body.

Environment

• FXServer b96 (cfx-server_win_x64), FiveM for GTAV Enhanced early access
• Windows 11
• Reproduced with a plain Lua resource, no dependencies

Impact

Any resource exposing an HTTP API with POST endpoints stops working —
webhook receivers, admin/dev tooling, external integrations. GET-only
resources are unaffected.

[wolfram-cfx]

Thanks, we are looking into this.

[wolfram-cfx]

Duplicate of #37. My fix for a future patch fixes both.