DWC destroyed config.g

resam

Hi,

Bug report:

DuetWifi 1.19.2 + DWC

I was editing my config.g via the web editor, and clicked save - and got a weird AJAX error and a missing config.g!
Only the config.g.bak was still there, but the "last modified" date is 2 weeks ago - so not the most recent bak file I presume.
https://imgur.com/a/QJslw

This is the first time this happened - must be some weird edge case, since I can't reproduce it again…

So, just a word of advice, until I can track this down: MAKE A BACKUP! Luckily I had almost all recent changes in a git repository.

resam

Hmm weird things are happening - halloween around the corner?

Somehow I now am completely unable to modify my config.g via DWC. I always end up with above error.
I managed to get the following serial debug output:

New conn on socket 0 for local port 80
HTTP connection accepted
Found responder
Received 615 bytes
Sending reply, file = no
HTTP req, command words { GET /rr_delete HTTP/1.0 }, parameters { name=0:/sys/config.g.bak }
New conn on socket 0 for local port 80
HTTP connection accepted
Found responder
Received 632 bytes
Sending reply, file = no
HTTP req, command words { GET /rr_move HTTP/1.0 }, parameters { old=0:/sys/config.g new=0:/sys/config.g.bak }
New conn on socket 0 for local port 80
HTTP connection accepted
Found responder
Received 2048 bytes
Sending reply, file = no
Webserver: rejecting message with: 500 too many header key-value pairs
Received 2048 bytes

resam

Ok - I think I found the culprit!

I was running DWC behind an nginx reverse proxy (proxy_pass).
Apparently this causes problems: [c]proxy_set_header Host $http_host;[/c], because it will append the port number the the Host header [c]10.0.0.42:80[/c], which then, I think, causes an error here: https://github.com/dc42/RepRapFirmware/blob/871c22c0c5b1c5479488014f7d428efe423c38c7/src/DuetNG/HttpResponder.cpp#L360
Removing the proxy_set_header, which was part of include proxy_params, resolved this issue.

All in all a bunch of weird configurations & errors on my side. Still surprised that the config.g just disappeared.