shared xDAV resources

Anatoli me at
Fri May 25 00:22:22 EDT 2018

Bron, Ken,

I've just created a new issue for this:, so it's not lost 
in the mails archive.

Please let us know if the community can sponsor the development.


*From:* Anatoli
*Sent:* Monday, April 09, 2018 00:40
*To:* Cyrus Devel
*Subject:* Re: shared xDAV resources

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 

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.
> Bron.
> 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 at domain>/
>> <A:propfind xmlns:A="DAV:">
>> ...
>> The server responds with:
>> HTTP/1.1 207 Multi-Status
>> <A:multistatus xmlns:A="DAV:" ...>
>>   <A:response>
>> <A:href>/dav/calendars/user/<user at domain>/</A:href>
>>     <A:propstat>
>> ...
>>   </A:response>
>>   <A:response>
>> <A:href>/dav/calendars/user/<user at domain>/Default/</A:href>
>>     <A:propstat>
>>       <A:prop>
>> ...
>> 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/t3 at as iOS is pointed to it by 
>> Cyrus). In the attached file goes the telemetry for the rest of the 
>> communication.
>> Thanks,
>> Anatoli
>> ---------- t3 at <mailto:t3 at> 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
>> Host:
>> 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:">
>>   <A:prop>
>>     <A:current-user-principal/>
>>     <A:principal-URL/>
>>     <A:resourcetype/>
>>   </A:prop>
>> </A:propfind>
>> >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:response>
>>     <A:href>*/dav/calendars/shared/*</A:href>
>>     <A:propstat>
>>       <A:prop>
>>         <A:current-user-principal>
>>           <A:href>*/dav/principals/user/t3 at*</A:href>
>>         </A:current-user-principal>
>>         <A:resourcetype>
>>           <A:collection/>
>>           <C:calendar/>
>>         </A:resourcetype>
>>       </A:prop>
>>       <A:status>HTTP/1.1 200 OK</A:status>
>>     </A:propstat>
>>   </A:response>
>> </A:multistatus>
>> <1521968736<OPTIONS /dav/principals/user/ HTTP/1.1
>> Host:
>> 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:
>>  *
>>     |telemetry.log|
>>       36k (text/x-log)
> --
>   Bron Gondwana, CEO, FastMail Pty Ltd
> brong at

Kenneth Murchison
Cyrus Development Team
FastMail Pty Ltd

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