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[bug]: Replayer splits comma-separated request headers, causing duplicate-name fields that break dict(**request.headers) middlewares

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#4,164 1 commento 0 reazioni 0 assegnatari Vedi su GitHub

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Valutazione

Difficoltà
2/5
Tempo stimato
1-3 ore
Idoneità per principianti
25/100
Tipo di issue
Bug
Chiarezza
Specificata chiaramente
Stato di attività
Ferma
Stack tecnologico
go
Ambito
api, testing-qa

Direzione di ricerca

Inizia in pkg/util.go, su ToHTTPHeader intorno alla riga 206, quindi confrontalo con ToYamlHTTPHeader intorno alla riga 153 e rivedi PR #4163. Riproduci il replay in stile axios descritto nell'issue e verifica che gli header della richiesta separati da virgole non vengano suddivisi in campi duplicati, mentre Set-Cookie rimane invariato.

Scritto dal modello di indicizzazione a partire dal testo della issue.

Descrizione

bug
👀 Is there an existing issue for this?

I have searched and didn't find a similar issue.

👍 Current behavior

pkg.ToHTTPHeader (pkg/util.go) splits every recorded header value on commas:

header[i] = strings.Split(j, ",")

Go's http.Client then writes one wire header per slice element. A request the original client sent as one header with comma-separated values fans out into multiple duplicate-name fields during replay.

For axios-style traffic, the recorded YAML carries:

header:
  Accept: application/json, text/plain, */*
  Accept-Encoding: gzip, compress, deflate, br

…which is axios's default. At replay time the wire is:

Accept: application/json
Accept: text/plain
Accept: */*
Accept-Encoding: gzip
Accept-Encoding: compress
Accept-Encoding: deflate
Accept-Encoding: br

Strict server middlewares that build a response via Response(headers=dict(**request.headers), ...) raise:

TypeError: dict() got multiple values for keyword argument 'accept'

…on duplicate field names. This is a known FastAPI / Starlette failure mode — any service with a metrics / observability middleware using that pattern returns HTTP 500 with Content-Type: text/plain body Internal Server Error during replay, even though the original request was well-formed.

👟 Steps to Replicate
  1. Stand up a FastAPI app with a custom middleware that does: 
    class MetricsMiddleware(BaseHTTPMiddleware):
    async def dispatch(self, request, call_next):
        response = await call_next(request)
        Response(headers=dict(**request.headers), status_code=response.status_code)
        return response
  2. Record a single GET to any endpoint using axios (or any client that sets Accept: application/json, text/plain, */*).
  3. keploy test against the recording.
  4. Observe 500 status, Content-Type: text/plain, body Internal Server Error. The app log shows TypeError: dict() got multiple values for keyword argument 'accept'.

A minimal reproduction with both the buggy and fixed middleware variants is available locally on request — runs in ~10 seconds via Docker.

📜 Logs (if any)

App side (uvicorn fallback page):

[ERROR] Exception in ASGI application
  File ".../glo_fastapi/metrics/middleware.py", line 55, in __call__
    response = Response(headers=dict(**request.headers), status_code=status_code)
TypeError: dict() got multiple values for keyword argument 'accept'

Keploy proxy log showing the wire-level fan-out (Accept is a 3-element slice, Accept-Encoding is 4):

Sending request to user app:&{GET ... HTTP/1.1 1 1
  map[Accept:[application/json  text/plain  */*]
      Accept-Encoding:[gzip  compress  deflate  br]
      ...
🌎 Where it happens

pkg/util.go:206 ToHTTPHeader. The companion ToYamlHTTPHeader (pkg/util.go:153) collapses repeated same-name headers to a single comma-folded string at record time, so the replay-side split is lossy by design — the YAML cannot distinguish "one header with internal commas" from "N repeated headers" and currently always picks the latter on replay.

Expected

Per RFC 7230 §3.2.2, a comma-folded single header is the canonical form for list-valued headers (Accept, Accept-Encoding, Baggage, Forwarded, Via, ...) and is semantically equivalent at the receiver to repeated same-name fields. Replaying the recorded value as one wire header per YAML key matches what most clients (axios, requests, fetch) actually emit and avoids the strict-middleware fan-out crash.

🔗 Fix

PR #4163 (fix(replay): fold comma-separated request headers into a single wire field) — keeps Set-Cookie (a response header, not built by this helper) untouched.

Lingua principale
Go
Stelle
18.5k
Fork
2.4k
Merge medio
19h 24m
PR unite (30g)
71

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