Change OAuth2 redirect link to relative link

[firlevapz]

Fix #19400

fix issue with third-party apps like rocket.chat
where browser in external window is opened
and thus oauth2 login does not work

Signed-off-by: Fabian Helm firlevapz@gmail.com

[kesselb]

Have you tested the change with a Nextcloud 18 instance? You mentioned 16.0.8 in #19400.

[firlevapz]

I'm running the server via snap with version 17.0.3 where the problem still persists (and the fix is working), I will try it with nextcloud 18 on a testing instance and then tell you

[kesselb]

Thanks 👍

[firlevapz]

I just tested it with version 18.0.1 and the problem still persists and this patch solves it.

I also tested the nextcloud desktop client and mobile client and they are both still working with this patch applied.

[rullzer]

I'm a bit puzzled what this solves?
Do full links get opened in an external program? (if so they should probably check if the url is the same?).

[firlevapz]

The rocket.chat desktop client unfortunately automatically opens absolute urls in a new, external browser-window - if it's a relative link, then you continue in the electron app and oauth2 is working as it should.

Unfortunately i have no idea, how to adapt the code for this client, and the easiest solution I found for this issue between rocket-chat and nextcloud would be this proposed change here.
Do you have any objections that changing the link to a relative url is a security issue or it could break other functionalities?

[rullzer]

Should be fine IMO

[firlevapz]

@nickvergessen @icewind1991 @ChristophWurst sorry to bother you, but it would be great if you could review this one-line-PR to solve the login-troubles with rocket-chat on my nextcloud-instance

[ChristophWurst]

👍 🐘

[welcome]

Thanks for your first pull request and welcome to the community! Feel free to keep them coming! If you are looking for issues to tackle then have a look at this selection: https://github.com/nextcloud/server/issues?q=is%3Aopen+is%3Aissue+label%3A%22good+first+issue%22

[holzhannes]

May you add this one line change to Milestone 19.0.1? Would be very kind 😊 or is it not possible?

[rullzer]

/backport to stable19