External Sites: How to debug?

🍱 Features & apps
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Hi all

Situation
I’m using [Nextcloud Hub 8] (29.0.4). I configured a couple of web apps as external sites, which all are working, except for one.

The one I have problems with is an embeded device (web interface of network player) running in the same network segment, no firewall in between. When I directly access the related web app, everything works fine. When I access it through external sites, the main screen of the app is displayed (all ressources are correctly loaded). On the main screen, the device can be powered on (from standby), which takes up to 8 seconds. When directly accessing the web interface the browser gets a response from the device after powering on (indicating the device is ready). Via external sites nothing happens, the browser doesn’t get any response from Nextcloud, not even an error.

I was checking the Nextcloud logs to see if there is any error or other related information but couldn’t find any (I can only see the initial request coming in and being proxied to the device). Thinking, this could be a timeout issue in the nextcloud reverse proxy component, i was checking the configuration in the Nextcloud UI if there is an option to configure the timeout, which i couldn’t find. Also in the NC documentation i didn’t find information about an config.cnf parameter to control the timeout behauviour.

Question

  • Does anybody know how long the timeout of the NC reverse proxy component is?
  • Does anybody know if this timeout can be configured somewhere?
  • Any idea on how to get more logs from the external sites component?
  • Any other ideas what the problem could be or how i could track it done?

Thanks a lot for your input!

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You won’t see anything the logs because there is no proxying occurring. All this app does is embed the external site in an iframe. It’s likely triggering some security in your browser that the target site has enabled. This will be visible in your browser inspector.

Some further details that you might find helpful: Linking external sites — Nextcloud latest Administration Manual latest documentation

1 Like
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Ui… i completely missed “IFrame” in the NC docs. I was only looking at the network tab in the browser tools and there is no indication if a request sent from an IFrame or the main window. My bad, thanks a lot for pointing out.

Still, the situation is weird, since the main screen of the application is loaded in the frame, so at least parts of it are working. Which would rather not be the case if there was some server wide X-Frame or CSP parameters set. However, I will dig a big more into that direction.

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You were right, the problem seems to be related the cross site handling with the IFrame. I was able to track it down to:

Uncaught DOMException: Permission denied to access property “ajax” on cross-origin object

“Funny” thing is, that the problem first and only occurs when jQuery is executing ajax requests, all the other requests (for static documents and media) is working.

This is new to me, i need to dig a bit into this topic. If someone has a hint, very welcome.