Denon AVR-4311CI Recognized But Not Authorized

[Nadahar]

It's a while ago now, but I actually came across some information about this somewhere. I just can't remember where... as far as I remember, it isn't hard to implement a "faked authorization", in fact UMS already does this for Xbox.

After thinking a bit, I think I might have found it: https://docs.microsoft.com/en-us/opensp ... f74eec93f2

If you download some of those PDF's, I think you will actually find the "service" described.

[Nadahar]

The log excerpt doesn't make that much sense to me either. Maybe there's a "hole" in the logging there (blame me, I wrote it), so that the content of the request is missing? Or maybe the fact that the request is empty is the reason for the "No content" reply. I don't remember the details of the subscription mechanism, but I'm pretty sure it's supposed to have a SOAP content with the details of what it wants to subscribe to.

It might be that the information UMS sends is lacking in a way that confuses the renderer in such a way that it triggers an empty subscription request.

Did you look at the "authorization service"? I far as I remember, all UMS has to do is to reply with "1" to confirm that it is authorized. Since we don't actually implement the DRM, we don't have to do a real authorization either, and ergo we can "authorize" everybody that asks.

The real problem, as I see it, is renderer implementations that requires the authorization when no DRM content is actually served. Xbox does this, and it seems like so does the Denon. I can't really understand the rationale behind this, except if the intention is to make it work with Microsoft "servers" exclusively.

[atamariya]

Just a suggestion - try to push HTTP 200 response instead of HTTP 204 for this specific case.

[Nadahar]

I gave up on trying to use wireshark to understand the upnp conversations. I got stuck on the http2 traffic.

I don't thin there should be any HTTP/2 traffic there, I certainly know that UMS doesn't support it. I don't even know if it has been added to UPnP AV, but the "original" UPnP AV was written for HTTP/1.1.

It can be difficult to find the way in wireshark, what I usually do is to find some packet that belongs to the communication I'm interested in, and then rightclick and "follow TCP stream" or something like that. You will then get that "conversation" filtered out and nicely merged together in a text document where you can read the exchange.

I didn't see any indication in the logs that a request was being made for authorization. Now that you mention it, right after I finish writing this response, I'm going set one or more breakpoints to see if that part of the code is being touched.
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The service must be announced in the "UPnP Description" for the renderer to attempt to use it. This smells a bit like if something is missing from UMS' description.

I agree.

The 4311 was first released around the time of the initial development of MS-DRMND (circa 2010) Denon is very sensitive about digital rights. In fact when playing back DSD content, it disables some(all?) potential pathways which could allow for digital copying. I think the 4311 was one of the first Airplay enabled receivers (v 1.0). I have no idea whether any of this affected Denon's decisions regarding 4311 media renderer functionality.

I still don't understand it, no matter how "careful" they want to be, there's no point in trying to "enforce" anything for content that doesn't have said DRM/encryption. It doesn't become any "less copyable", even if you play it on a "Microsoft server". It simply serves no purpose that I can see. I rather suspect that they have either peeked at or "gotten help from" Microsoft when making their renderer implementation, and that this non-standard stuff has ended up in there by mistake. Alternatively, they have struck some deal with Microsoft where Microsoft has paid them to make it only work with "Microsoft servers". I still beats me.

There are other DRM implementations in DLNA, this particular one is non-standard and non-compliant with the standard as far as I can tell. If they were so worried about DRM, one would think they would implement some of the "standard DLNA" DRM schemes. But again, DRM doesn't do anything as long as the content is "open" anyway. You can't expect people to "DRM encrypt" their home videos to be able to watch them at their TV...?