Comments on: Digging Into The Exchange ActiveSync Protocol

By: Andreas

Andreas — Sat, 12 Nov 2011 13:49:32 +0000

Is this hand-crafted with Fiddler? I’m not sure why, but Exchange does not always seem to like POST requests with a content-length of 0. (Zero-length POSTs serve no purpose though…) If you’re testing with Fiddler it seems the GET is the only test that will give you the basic info you want for verifying that the server is online (in addition to using OPTIONS of course).
For further tests I recommend my EAS MD utility available in the downloads section – you can inspect the results in Fiddler of course. There’s also source code available if you want to implement your own tools.

By: da

da — Fri, 11 Nov 2011 17:23:48 +0000

I am also getting a 400 Bad Request Error. We are using EXCHANGE 2007 and the supported ASPProtocolVersion based on your OPTIONS strategy shows that 1.0…12.0,12.1 are supported. I used this in the POST headers to the server and still get 400 BAD Request.

https://xxxxxxx.com/Microsoft-Server-ActiveSync?User=userx&DeviceId=12345&DeviceType=Pocket_PC&Cmd=Sync

User-Agent: MSFT-PPC/5.2.5300
Content-Length: 0
Authorization: Basic bmV0XHN0b3Jtc2FnZTpwYXNzd29yZA==
Content-Type: application/vnd.ms-sync.WBXML
MS-ASProtocolVersion: 12.0

The response in fiddler is
HTTP/1.1 400 Bad Request
Cache-Control: private
Content-Type: text/html
Server: Microsoft-IIS/7.0
X-AspNet-Version: 2.0.50727
MS-Server-ActiveSync: 8.3
X-Powered-By: ASP.NET
Date: Fri, 11 Nov 2011 17:10:03 GMT
Connection: close

Bad Request

Any ideas what could be the problem?

By: Andreas

Andreas — Mon, 10 Oct 2011 19:03:18 +0000

Something like this?
http://msdn.microsoft.com/en-us/library/ee203348(v=EXCHG.80).aspx

By: Neha

Neha — Mon, 10 Oct 2011 05:14:51 +0000

Hi,

Thanks for the detailed explanation.I would like to ask something. For EAS, I want to download the headers only(not body of the mail).So which command i shall use or else what is the way to download the headers only.

Please help me out.

Thanks in Advance,
Neha

By: Andreas

Andreas — Fri, 26 Aug 2011 07:52:53 +0000

chkan,

Thanks for clearing that up! Your explanation was more precise and better than mine

By: ckhan

ckhan — Fri, 26 Aug 2011 05:28:28 +0000

Actually, the 64 is 0×40, ie bit 6 on.
This is defined in the WAP Binary XML spec: http://www.w3.org/1999/06/NOTE-wbxml-19990624/#_Toc443384904 (I don’t see it anywhere in the MS-ASWBXML doc on MSDN).

From that w3.org spec:
“Bit 6 Indicates whether this tag begins an element containing content. If this bit is zero, the tag contains no content and no end tag. If this bit is one, the tag is followed by any content it contains and is terminated by an END token”

Without bit 6 on (ie, sending 0×16 instead of 0×56) you’re telling Exchange that there’s no content in your element, which isn’t true, so it rejects the request.

By: Exchange ActiveSync Building Blocks – Intro | MobilityDojo.net

Exchange ActiveSync Building Blocks – Intro | MobilityDojo.net — Wed, 10 Aug 2011 20:31:30 +0000

[...] details of the Exchange ActiveSync protocol. I have covered this topic before to a certain degree: http://mobilitydojo.net/2010/03/17/digging-into-the-exchange-activesync-protocol/ Also explaining my EAS MD utility: [...]

By: Andreas

Andreas — Thu, 14 Jul 2011 19:06:04 +0000

Because 64 is a magic number?

No, that’s probably not the reason

I can’t remember the link to the msdn page I used as reference material. But the initial FolderSync is an “empty” sync request. You don’t need to include the folder hierarchy, (this is part of what you’re interested in acquiring), and since you haven’t synced before you don’t have a sync key either. So the first sync key is 0, and you know that the max length of the sync key is 64 characters. This is just the way my initial wbxml works out I guess – not able to give a better explanation at the moment.

Your xml was filtered out by the WordPress commenting system which doesn’t allow that kind of text so I’m not able to compare notes on that part.

By: Robert

Robert — Thu, 14 Jul 2011 09:49:19 +0000

Hi Andreas,

I’m trying to build an ActiveSync library and am currently stuck at the first try to send the wbxml code. Apparently Exchange is terminating the handshake because it doesn’t recognize my request code.

Comparing it with your wbxml example, I see that you don’t send the actual codes as defined in the FolderHierarchy codepage, but add 64 to them. Can you explain why?

Here is my Request in plain xml and the encoded variant:

03 01 6a 00 00 07 16 12 03 30 00 01 01

Your variant:
03 01 6a 00 00 07 56 52 03 30 00 01 01

Thanks for your help!

By: Andreas

Andreas — Wed, 13 Apr 2011 09:53:43 +0000

Kristijan,

Glad to be of help – and it’s great to have contributed to an open-source project