How to verify if the request originated from PBI Desktop or PBI on-prem gateway in Custom Connector?

[Mohanasudharsan]

We are developing a custom connector that supports both Power BI Desktop and Power BI on-prem gateway for Service. The connector user web.contents to fetch the REST API results from our database. 
We come across a blocker where we have to handle queries differently for the Power BI desktop and service in the same MEZ(custom connector) file. 

Any idea how to validate the request from the very first request sent from the clients(Desktop or Service of PBI)? It would be easy even if we know anyone unique specific parameter or header.

[Mohanasudharsan]

Thanks for the response.
Is there any other way to validate request via web.contents request initiated from desktop or server?

[lbendlin]

Same idea. Azure service uses a specific IP range. You find that in the documentation.

[lbendlin]

Gateways have a fixed set of IP addresses.