Bron, Ken,

Thanks for your explanations.

Do you consider this is something possible to implement for an outside developer, i.e. without Cyrus HTTP/DB implementation internals understanding, nor solid knowledge of xDAV RFCs? I'd like to collaborate, but I believe it only makes sense to start this work if I could finish it without too much effort to become fluent with the related internals/standards.

On the other hand, if I don't have a reasonable chance to implement it myself, could I sponsor the development by your team or help your team in other ways (e.g. extensive testing, logs/telemetry, etc.)?

I have the Cyrus xDAV functionality deployed experimentally at one organization, everything looks good so far, but the fact that shared resources (calendars and addressbooks) can't be accessed from iOS devices obstructs its definitive deployment there and at other organizations. WebDAV resources work well on all devices with some minor issues on macOS (I'm debugging them now, looks like they only occur on previous versions of macOS, i.e. El Capitan).

> I originally wrote the code to handle public calendars in the "shared" namespace, but I focused on user calendars first, and public calendar support got tossed on the back burner.  It appears that the code for public calendars partly works.

Public calendars actually work quite well, if the device can discover them. Currently, I've tested them with Thunderbird and haven't found any issues.

Remote addressbooks are not supported in Thunderbird, so I use /CardBook/ add-on and it works well with shared addressbooks, no issues detected. /Evolution/ supports CardDAV natively and also works well with shared addressbooks.


*From:* Ken Murchison
*Sent:* Saturday, April 07, 2018 21:53
*To:* Bron Gondwana, Cyrus Devel
*Cc:* Ken Murchison
*Subject:* Re: shared xDAV resources

I originally wrote the code to handle public calendars in the "shared" namespace, but I focused on user calendars first, and public calendar support got tossed on the back burner.  It appears that the code for public calendars partly works.

My first thought to get auto-discovery of public calendars is to add /dav/calendars as a second calendar-home-set for users and see what the Apple clients do with that.  I don't know if they can handle multiple home-sets.  If that doesn't work, then we could map public calendars into the user's home-set via the same subscription mechanism that we use for CalDAV sharing.

To answer the original question, calendars are enumerated by meth_propfind() and propfind_by_collection() in http_dav.c

On 4/7/18 8:25 PM, Bron Gondwana wrote:
Ken knows this code best.  I bet there's something which is requiring that there's a user on the mboxname because we implement the same behaviour at FastMail by having a separate user on which shared resources are kept.  The DAV resources are stored per-user, and without a place to keep them for "shared calendars" that code might just not be accessible.  I'm sure it would be possible to create a shared DAV database as well for this case, but it just needs some programming effort.


On Sun, 8 Apr 2018, at 07:30, Anatoli wrote:
Hi All,

I'm trying to understand the code responsible for enumerating user calendars (and xDAV resources in general) to try to make the discovery work for shared resources too (currently there's no way to access shared resources with Apple xDAV client implementation, yes with Thunderbird as it doesn't use the discovery mechanism, but instead should be pointed to the exact URL for each calendar). If I understand it correctly, the functionality is in imap/http_caldav.c.

Could you please point me to the place where the enumeration occurs and briefly mention how the general workflow looks like?

The client asks for:

PROPFIND /dav/calendars/user/<user@domain>/

<A:propfind xmlns:A="DAV:">

The server responds with:

HTTP/1.1 207 Multi-Status

<A:multistatus xmlns:A="DAV:" ...>

The idea is to include in the returned lists the shared calendars too with the discovery logic based on the IMAP shared folders.

Below goes the initial exchange between the calendar app on iOS 10.2.6 and Cyrus 3.0.5 when the exact URL (/dav/calendars/shared/) for the shared calendar is provided in the advanced settings of the app (the URL finally resets to the user principals folder (/dav/principals/user/ as iOS is pointed to it by Cyrus). In the attached file goes the telemetry for the rest of the communication.


---------- <> Sun Mar 25 06:05:36 2018

<1521968736<*PROPFIND* */dav/calendars/shared/* HTTP/1.1
Accept: */*
Content-type: text/xml
Connection: keep-alive
Content-length: 181
User-agent: iOS/11.2.6 (15D100) accountsd/1.0
Prefer: return=minimal
Depth: 0
Brief: t
Accept-language: en-us
Authorization: Basic ...
Accept-encoding: br, gzip, deflate

<1521968736<<?xml version="1.0" encoding="UTF-8"?>
<A:propfind xmlns:A="DAV:">

>1521968736>HTTP/1.1 207 Multi-Status
Date: Sun, 25 Mar 2018 09:05:36 GMT
Strict-Transport-Security: max-age=600
Vary: Accept-Encoding, Brief, Prefer
Preference-Applied: return=minimal
Content-Type: application/xml; charset=utf-8
Content-Length: 546

<?xml version="1.0" encoding="utf-8"?>
<A:multistatus xmlns:A="DAV:" xmlns:C="urn:ietf:params:xml:ns:caldav">
      <A:status>HTTP/1.1 200 OK</A:status>

<1521968736<OPTIONS /dav/principals/user/ HTTP/1.1
Connection: keep-alive
Accept: */*
User-Agent: iOS/11.2.6 (15D100) accountsd/1.0
Accept-Language: en-us
Content-Length: 0
Accept-Encoding: br, gzip, deflate

>1521968736>HTTP/1.1 200 OK
Date: Sun, 25 Mar 2018 09:05:36 GMT
Strict-Transport-Security: max-age=600
Cache-Control: no-cache
Link: </dav/principals/.server-info>; rel="server-info"; token="80769c2c66d340ecd178710db26d56b9c4699e3e"
DAV: 1, 2, 3, access-control, extended-mkcol, resource-sharing
DAV: calendar-access, calendar-auto-schedule
DAV: calendar-query-extended, calendar-availability, calendar-managed-attachments
DAV: calendarserver-sharing, inbox-availability
DAV: addressbook
Content-Length: 0

Email had 1 attachment:

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  Bron Gondwana, CEO, FastMail Pty Ltd

Kenneth Murchison
Cyrus Development Team
FastMail Pty Ltd

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