Avoid determination of document editor in per-user-encryption setups

[mario-van-zadel]

• Resolves: Writing documents with enabled per-user encryption keys fails (Private Key missing for user) #1379
• Target version: master

Summary

When saving a document with enabled per-user encryption keys, an exception Private Key missing for user: please try to log-out and log-in again is thrown.

This is caused by the determination of the user who is editing the document to be able to trace the document's changes (https://github.com/nextcloud/richdocuments/blob/master/lib/Controller/WopiController.php#L407). Setting a specific user causes the usage of the user-specific encryption key instead of using the incognito mode (like it's done in getFile: https://github.com/nextcloud/richdocuments/blob/master/lib/Controller/WopiController.php#L349).

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Documentation (manuals or wiki) has been updated or is not required

[mario-van-zadel]

@juliushaertl Do you know how to solve the failing tests? I'm using OCA\Encryption\Util to determine if the master-key is enabled, but it's not part of christophwurst/nextcloud. There seems not to be an isMasterKeyEnabled() method as part of Nextcloud's public API.

[juliushaertl]

I'm using OCA\Encryption\Util to determine if the master-key is enabled, but it's not part of christophwurst/nextcloud. There seems not to be an isMasterKeyEnabled() method as part of Nextcloud's public API.

Yes, the server-side encryption is built in a modular way where the default encryption module (the encryption app that is shipped) is taking care of the implementation in regards to user/master key encryption, so that part is only in the app and not in the server encryption API. That is of course not ideal from an integrating apps perspective since we cannot be sure if the app is enabled or not. Due to that the app is disabled in the tests the autoloader is not able to inject the Util instance into the WopiController constructor. Probably the most suitable way would be to just avoid using dependency injection for the master key check and do something like this for the check:

$isMasterKeyEnabled = false;
try {
	$util = \OC::$server->query(\OCA\Encryption\Util::class);
	$isMasterKeyEnabled = $util->isMasterKeyEnabled();
} catch(\OCP\AppFramework\QueryException $e) {
	// No encryption module enabled
}

[juliushaertl]

/backport to stable3.7