drogonframework/drogon

Header "connection: close" disconnects the client before Response Stream is started

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#2,276 opened on Mar 10, 2025

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help wanted

Description

Describe the bug

In our project we use Drogon for HTTP response streaming. However, when client includes connection header that is not keep-alive, response stream is immediaitely closed.

Source code: https://github.com/drogonframework/drogon/blob/cbf63f8fc4d849bbb82eeb1c83fcf8ff953f19f3/lib/src/HttpServer.cc#L981-L990

It is common practice to use connection: close to indicate that connection should be closed after processing is finished*, meaning - after HTTP response stream is done.

In our setup, we needed to patch drogon like this: https://github.com/openvinotoolkit/model_server/pull/3113/commits/8ca2918c04ae9fab77ad157dcd23673971d84420

To Reproduce Steps to reproduce the behavior:

  1. Start drogon with streaming response endpoint defined
  2. Request with any client including header connection: close
  3. Request is immediately rejected

Expected behavior Connection is closed after response streaming is finished.

Desktop (please complete the following information):

  • OS: ubuntu, redhat, windows
  • Client: any

More context We are using Continue VSCode plugin as a client for code completions: https://github.com/continuedev/continue We use drogon to serve http streaming (code completions), however, this plugin (client) sends connection: close header.

Contributor guide

Tech stack
cpp
Domain
backendapi
Issue type
bug
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.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
C++ knowledgeHTTP protocol basicsDrogon framework basics
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
50
Research direction
The bug is in HttpServer.cc at line 981-990. The issue describes that when the client sends 'connection: close', the response stream is immediately closed instead of after streaming finishes. A patch is provided in the linked pull request (https://github.com/openvinotoolkit/model server/pull/3113/commits/8ca2918c04ae9fab77ad157dcd23673971d84420) which shows the exact changes needed. Review this patch and apply a similar fix to Drogon's HttpServer.cc, ensuring that the connection is closed only after the response stream is complete.