Auth API: HTTP 100-continue support

[jasper-ved]

• This is not a support question, I have read about opensource and will send support questions to the IRC channel, GitHub Discussions or the mailing list.

• I have read and understood the 'out in the open' support policy

• Program: Authoritative

• Issue type: Bug report

Short description

Restsharp, an HTTP API client for .net, sends out a request with a HTTP 100-continue, but the API doesn't respond to with 100-Continue for the client to give the payload and the request times out after that (Apache2 as proxy after 5 seconds).

Environment

• Operating system: Ubuntu 24.04
• Software version: 4.9.2
• Software source: PowerDNS repository

Steps to reproduce

1. Steps to reproduce is hard to do here, as this is a specific client (Restsharp) with a specific setup for that user.
2. gave the user https://stackoverflow.com/questions/14063327/how-to-disable-the-expect-100-continue-header-in-httpwebrequest-for-a-single to test
3. Disabling 100-continue support for the client fixed the issue

difference in the requests between Restsharp and curl as captured by tcpdump:

PATCH /api/v1/servers/localhost/zones/zone.nl. HTTP/1.1
Host: 127.0.0.1:8081
User-Agent: RestSharp/112.0.0.0
X-API-Key: <KEY>
Accept: application/json, text/json, text/x-json, text/javascript, application/xml, text/xml
Content-Type: application/json; charset=utf-8
**Expect: 100-continue**
Accept-Encoding: gzip
X-Forwarded-For: <IP>
X-Forwarded-Host: <HOST>
X-Forwarded-Server: <HOST>
Content-Length: 171
Connection: Keep-Alive

PATCH /api/v1/servers/localhost/zones/zone.nl HTTP/1.1
Host: 127.0.0.1:8081
User-Agent: curl/7.81.0
Accept: */*
X-API-Key: <KEY>
Content-Type: application/x-www-form-urlencoded
X-Forwarded-For: <IP>
X-Forwarded-Host: <HOST>
X-Forwarded-Server: <HOST>
Content-Length: 182
Connection: Keep-Alive
{"rrsets": [{"changetype": "REPLACE", "type": "A", "name": "<name>.zone.nl.", "ttl":3600, "records": [{"content": "<IP>", "disabled":false}]}]}

Expected behaviour

API should respond with a continue for the client to do the rest of the request.

Actual behaviour

API gives no response at all as it is waiting on the payload. but not sending the client the response to deliver that payload.