Calendar invitation response (guests and comment) not processed

[wiswedel]

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Steps to reproduce

1. Create a calendar event
2. Invite somebody by email => invitee receives an email
3. As the email invitee, click on More options... in the email => browser opens with response page
4. Pick "accept", fill in a number of guests and leave a comment

5. Hit Save => see Your attendance was updated successfully.

Expected behaviour

• The calendar event in the database column oc_calendarobjects.calendardata gets updated with X-RESPONSE-COMMENT and X-NUM-GUESTS
• The information is shown somewhere on the calendar GUI

Actual behaviour

• The attendance gets updated, guests and comments never show up anywhere

Server configuration

• Nextcloud 20.0.1
• Calendar 2.1.2

Initial evaluation

The feature comes from the server, that's why I'm posting here and not in the calendar repo.

server/apps/dav/lib/Controller/InvitationResponseController.php

Lines 230 to 236 in 2c6bbe7

	if ($comment) {
	$attendee->add('X-RESPONSE-COMMENT', $comment);
	$vEvent->add('COMMENT', $comment);
	}
	if ($guests) {
	$attendee->add('X-NUM-GUESTS', $guests);
	}

[szaimen]

I suppose this is still valid on NC21.0.2?

[ghost]

This issue has been automatically marked as stale because it has not had recent activity and seems to be missing some essential information. It will be closed if no further activity occurs. Thank you for your contributions.

[simonmicro]

I suppose this is still valid on NC21.0.2?

Indeed - this issue should be reopened!

[sbrueck]

Hello all, unfortunately this issue seems to persist. I am using version 22.2.3 with PHP 7.4.3 and MySQL 8.0.27. Unfortunately, data from the "Guests" and "Comments" fields are still not being transferred to the organizer or to the organizer's calendar. Could someone solve this in the meantime?

[tcitworld]

This is because Sabre doesn't take any custom fields from the iTip message, it just use the email to compare to event attendee existing fields.

https://github.com/nextcloud/3rdparty/blob/41d5f9752c7e0f2b690480a38ef5b9dddc357166/sabre/vobject/lib/ITip/Broker.php#L362-L369

X-RESPONSE-COMMENT and X-NUM-GUESTS are discarded after this.

I don't really know if there's a security issue in accepting attendee-level parameters at this level, so let's start with opening an issue at Sabre. The spec suggests the ATTENDEE property can be changed (from the table talked below), so it might be valid.

About the COMMENT property directly on the VEVENT, I'm again not sure if we can update the property as well.
https://datatracker.ietf.org/doc/html/rfc5546#section-3.2.3

An "Attendee" MAY include a message to the "Organizer" using the "COMMENT" property. For example, if the user indicates tentative acceptance and wants to let the "Organizer" know why, the reason can be expressed in the "COMMENT" property value.

The optional properties listed in the table below (those listed as "0+" or "0 or 1") MUST NOT be changed from those of the original request. If property changes are desired, the "COUNTER" message must be used.
COMMENT | 0+

I'm guessing the spec says you can add a COMMENT property to your REQUEST, but it won't be set as an event property (which kinda makes sense, as you can't know who added it), it's up to the system to forward it to the organizer. Either way Sabre doesn't support this either, so we can remove the following line in any case.

$vEvent->add('COMMENT', $comment);

Should we remove this feature altogether since it won't function until the underneath work has been done? Thoughts @nextcloud/calendar ?

[miaulalala]

We had the same issue for the X-NC-APPOINTMENTS property where it wasn't stored in the oc_calendarobject_props table. I suppose writing it to the ics and then having something to display these properties on the Calendar App side of things parsed from the ics could work. Because that part is fine: the ics will still contain the information when it is created in the iTip message for the InvitationResponseController and will be written to the oc_calendarobjects table like this too.

[ghost]

This issue has been automatically marked as stale because it has not had recent activity and seems to be missing some essential information. It will be closed if no further activity occurs. Thank you for your contributions.

[colans]

Related to #539

[ghost]

This issue has been automatically marked as stale because it has not had recent activity and seems to be missing some essential information. It will be closed if no further activity occurs. Thank you for your contributions.

[nextcloud-command]

This issue has been automatically marked as stale because it has not had recent activity and seems to be missing some essential information. It will be closed if no further activity occurs. Thank you for your contributions.

[nextcloud-command]

This issue has been automatically marked as stale because it has not had recent activity and seems to be missing some essential information. It will be closed if no further activity occurs. Thank you for your contributions.

[simonmicro]

Uhmm, I think this is still not fixed? Just commenting to remove the stale label.

[nextcloud-command]

This issue has been automatically marked as stale because it has not had recent activity and seems to be missing some essential information. It will be closed if no further activity occurs. Thank you for your contributions.

[miaulalala]

I have worked on this issue in the sabre code but I'm stuck on how to generate a message in parseMessageForAttendee, so the attendees are also getting the new comments. I think this has to do with the significant change hash.

Upstream PR (still a WIP!) for Sabre is here: https://github.com/sabre-io/vobject/pull/593/files, although after reading @tcitworld 's comment on the security implications and problems with replies, I am not sure it will be accepted.

Also, the export doesn't collect all data stored in the calendarobjects_props table (where the comment now is indeed stored after adding my changes) and does not show them on downloading / exporting the ICS.

I haven't figured out yet where the ICS is built or whether it is an export of the calendarobjects calendardata table (which I find doubtful, as the calendardata string does contain the comments).

Additionally, a frontend display of comments and an option to submit a comment would be nice.

[miaulalala]

After thinking this over, here's the current status:

1. X-NUM-GUESTS needs to be handled separately as this is not an RFC supported property. Same goes for X-RESPONSE-COMMENT.
2. Regarding the RFC: COMMENTs should only be sent to and from the ORGANIZER and not passed on to the other ATTENDEEs. cc @kesselb
3. Upstream fix should be done for the ORGANIZER, even if it isn't supported much (see next point).
4. The bad news is, we're going to disable the feature (for now). We have no way to display or export the COMMENT at all, our internal export function doesn't include the COMMENT either. It is stored on a DB level (oc_calendarobject_props) when the upstream fix is done but not before.
   Reasoning for removing: Google uses in- house properties and doesn't support COMMENTs only X-RESPONSE-COMMENTs. Thunderbird doesn't support COMMENTS at all. KDE Kalendar doesn't support them either AFAIK. SOGO Groupware may support them, TBD. If anyone wants to tell me how Outlook or Zimbra handles them, let me know. 🙏 an exported ICS would be much apprechated.
5. We are also considering refactoring the scheduling plugin so the iTip Broker class can be overwritten more easily. Currently it is instantiated via a call to new Broker() in the \Sabre\CalDAV\Schedule\Plugin::scheduleLocalDelivery method. Always passing an instance via constructor migt be an option, of via hooks or events. Overwriting the Broker would be 🔥 so we can extend it to suit our needs. Then we can also add support for non- RFC properties such as X-RESPONSE-COMMENTs and X-NUM-GUESTS.

[ChristophWurst]

PR is at #35761.