akka/akka-http

Restrict / review `Transfer-Encoding` header rendering

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#3,761 opened on Feb 15, 2021

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Description

Since #3754, we only support Transfer-Encoding: chunked headers and no other ones. The reasoning is that akka-http is implementing the "Transfer" part of HTTP. Leaving parsing or providing custom Transfer-Encoding headers open to the user will lead to confusion and bugs.

We should check that:

  • The Transfer-Encoding model could make sure that the latest entry is always chunked (see RFC), though that would change the error reporting for parsing as now implemented with #3754
  • User-provided Transfer-Encoding headers will always be ignored

Contributor guide

Tech stack
None
Domain
backendapi
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
HTTP Transfer Encoding knowledgeakka http internals
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
25
Research direction
Investigate the current implementation from PR #3754 to understand how Transfer Encoding headers are parsed and rendered. The goal is to restrict the model so that only 'chunked' is allowed and user provided headers are ignored. Look at the HttpHeader model and the rendering code to add validation. The issue mentions two checks: ensuring the latest entry is always 'chunked' and ignoring user provided headers. Consider how to integrate these without breaking existing error handling.
Restrict / review `Transfer-Encoding` header rendering · akka/akka-http#3761 | Good First Issue