404 error when accessing /Microsoft-Server-ActiveSync (possibly caused by user-agent string)

Apps & App Center
, ,
#1

Hello everyone!

UCS: 4.2-4 errata426
App Center compatibility: 4
Installed: letsencrypt=1.1.2-8 mailserver=11 open-xchange-text=7.8.4-ucs1 oxseforucs=7.8.4-ucs10 samba4=4.6
Upgradable: oxseforucs

I am running into a strange and unusual problem, when clients try to get the OPTIONS via the URL our.domain.tld/Microsoft-Server-ActiveSync. Depending on the user-agent string the request is served or it is rejected with a 404 by apache.

curl -i -u 'user:pass' -A "Thunderbird ActiveSync Lightnin" -X OPTIONS https://our.domain.tld/Microsoft-Server-ActiveSync/

HTTP/1.1 200 OK
Date: Thu, 20 Sep 2018 16:27:48 GMT
Server: grizzly/2.3.29
Strict-Transport-Security: max-age=15768000
X-Robots-Tag: none
Public: OPTIONS, POST
MS-ASProtocolVersions: 2.5,12.0,12.1
MS-ASProtocolCommands: Sync,FolderCreate,FolderDelete,FolderSync,FolderUpdate,GetAttachment,GetHierarchy,GetItemEstimate,MeetingResponse,MoveItems,Ping,Provision,ResolveRecipients,Search,SendMail,SmartForward,SmartReply,ValidateCert,Settings,ItemOperations
Pragma: no-cache
Allow: GET, HEAD, POST, TRACE, OPTIONS
Content-Length: 0
Via: 1.1 our.server.tld

If I add just one more character to the user-agent string, the request fails:

curl -i -u 'user:pass' -A "Thunderbird ActiveSync Lightning" -X OPTIONS https://our.domain.tld/Microsoft-Server-ActiveSync/

HTTP/1.1 404 Not Found
Date: Thu, 20 Sep 2018 16:31:30 GMT
Server: Openexchange WebDAV
Strict-Transport-Security: max-age=15768000
X-Robots-Tag: none
Content-Length: 0
Via: 1.1 our.server.tld

Unfortunately the logfiles haven’t been to helpful and I have been digging around the net and OXpedia for some days now. If anybody knows what could cause this behaviour, I will gladly accept any pointers to possible solutions I haven’t thought of yet.

If any logs or information is needed to further investigate this problem, just let my know.

Best regards,

Falk

#2

Hi Falk,

the OX integration on UCS is currently using the HTTP user agent to distinguish between HTTP requests for the OX middle ware and CalDAV requests. A list of user agent substrings that are interpreted as CalDAV request can be found in the UCR variable ox/caldav/useragent/whitelist. The substring Lightning is also part of this list, which might cause your problem.
You can alter the UCR variable according to your needs (remove Lightning or replace Lightning with a more appropriate string).

Best regards,

Sönke

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