Remote.app

Background

Remote.app uses the DAAP (Digital Audio Access Protocol) to communicate with iTunes. DAAP, is just HTTP over port 3689. Responses are returned in a binary format that lists different aspects of every request including its status code, DAAP protocol version and the server name. The following is some initial information gathered by mxweas

Finding clients

The Remote.app like most things uses Bonjour to find suitable clients. Once found it tries to initiate a session.

Initiate a session

First Remote.app calls /server-info on the server (iTunes) with the following headers:

User-Agent: Remote/1.0
Accept-Encoding: gzip
Viewer-Only-Client: 1
Connection: keep-alive

NOTE: /server-info will return nothing if the Viewer-Only-Client header is not set to 1.

Here is a plain text sample of what iTunes will usually return:

Tag: msrv, size: 252                                   ; Container of the Response
 Tag: mstt, Size:  4, Status: 200                      ; Response Status
 Tag: mpro, Size:  4, Version: 0.2.0.4                 ; DMAP Protocol Version
 Tag: apro, Size:  4, Version: 0.3.0.6                 ; DAAP Protocol Version
 Tag: aesv, Size:  4                                   ; Unknown
 Tag: aeFP, Size:  1                                   ; Unknown
 Tag: ated, Size:  2                                   ; Unknown
 Tag: msml, Size: 16                                   ; Unknown
 Tag: minm, Size: 15, Data: Max\342\200\231s Library   ; Server (iTunes Library) Name
 Tag: mslr, Size:  1, Data: True                       ; Login Required To Query
 Tag: mstm, Size:  4, Timeout: 1800 Seconds            ; Connection Timeout
 Tag: msal, Size:  1, Data: True                       ; Server Can Auto-Logout The Client
 Tag: msas, Size:  1                                   ; Unknown
 Tag: msup, Size:  1, Data: True                       ; Server Supports The /update Call
 Tag: mspi, Size:  1, Data: True                       ; Server Supports Persistent ID's
 Tag: msex, Size:  1, Data: True                       ; Server Supports Extensions
 Tag: msbr, Size:  1, Data: True                       ; Server Supports Browse
 Tag: msqy, Size:  1, Data: True                       ; Server Supports Query
 Tag: msix, Size:  1, Data: True                       ; Server Supports Indexing
 Tag: msrs, Size:  1, Data: True                       ; Server Supports The /resolve Call
 Tag: msdc, Size:  4, Count: 1                         ; # Of Database's Available
 Tag: mstc, Size:  4                                   ; Unknown
 Tag: msto, Size:  4                                   ; Unknown

Tag Description Help: DAAP - Server Info Request

Once that data has been received, Remote.app calls /ctrl-int on the server with the same headers as the /server-info call. Below is a sample return:

Tag: caci, Size 118

Next Remote.app calls /login?pairing-guid= with a random hex value that can only be assumed as a special representation of the 4 digit code used to pair in the Remote.app. The return response looks something like this:

Tag: mslog, Size: 24                                   ; Container
 Tag: mstt, Size:  4, Status: 200                      ; Response Status
 Tag: mlid, Size:  4, Id: <8-digit numeric code>       ; Session ID?

After this has completed the Remote.app uses its session-id in all further calls which I will be documenting later.