MIP SDK: fail to create FileHandler with error "Content protected by on prem servers is unsupported" - microsoft-information-protection

Question

We are developing an application to open and edit protected PDF files using the MIP SDK (we're currently using version 1.6.103).
So far, we were able to open files protected with different versions of Microsoft protection, including MicrosoftIRMServices version 1.
We are now hitting a problem with one of our customers. They keep their files on a SharePoint 2016 directory, which is configured to automatically add protection to all files uploaded. All their environment is on-premise and AD RMS Service is used for protection. They do not have Azure IP on server side.
When we download the resulting file and try to open, we create a mipns::FileEngine and then invoke CreateFileHandlerAsync() to create a mipns::FileHandler. This call fails with the following mipns::NetworkError:
NetworkError : Content protected by on prem servers is unsupported., NetworkError.Category=FailureResponseCode, HttpRequest.SanitizedUrl=https://api.aadrm.com/my/v2/enduserlicenses,
As the error suggests, I suspect the issue is with the usage of an on-premise protection.
I thought it might be resolved following the instructions at
https://learn.microsoft.com/en-us/information-protection/develop/quick-app-adrms#configuring-protection-api-in-c-to-use-ad-rms
so, following those instructions, I created the FileEngine with
ProtectionEngine::Settings engineSettings("", authDelegate, "");
engineSettings.SetProtectionCloudEndpointBaseUrl("http://<my server>/_wmcs/licensing");
but so far no success, although the error has changed and is now
NetworkError : The protection service is unavailable., NetworkError.Category=FailureResponseCode, HttpRequest.SanitizedUrl=https://<my server>/my/v1/enduserlicenses,
(where of course <my server> is replaced with a local service)
Am I going in the wrong direction? If not, perhaps I am using the wrong endpoint? How can I find the endpoint URL to be passed to SetProtectionCloudEndpointBaseUrl as suggested in the linked page?
Thanks

Answer 1

This is likely caused by a missing MDE install or MDE SRV record. You'll need to validate that mobile device extensions for AD RMS has been deployed and configured. If it has, you'll also need to validate that the SRV record is in place for any mail suffixes your customer is using. For example, if the RMS service is at RMS.FABRIKAM.COM, but your customer email addresses are #Contoso.com, you'd need an SRV record that looks like _rmsdisco._http._tcp.contoso.com which would then point to the server at RMS.FABRIKAM.COM.
The base URL isn't used in consumption scenarios. It's only for publishing. That said, looks like you've set the _wmcs endpoint, but we expect only the base for AD RMS:
ProtectionCloudEndpointBaseUrl = "https://rms.contoso.com"
That's only required when you don't provide a mip::Identity object when creating the file engine. If you do provide the identity, we'll use the domain suffix to look up the DNS record and chase that referral.