BackchannelHttpHandler issue repro project

This project serves as a repro project for an issue with OIDC running behind a corporate proxy.

How to use

• Set the correct AzureAD settings under the AzureAD section of the config
• Run a proxy that can tracks calls (fiddler is perfect, be sure to disable Act as a system proxy on startup)
• At Program.cs:37 you will find a commented line. Comment\Uncomment this line to see the different behaviour.

Result

When authenticating a user...

• ... without using HttpClient.DefaultProxy, you will see 2 calls in fiddler:
  • /<tenant-id>/v2.0/.well-known/openid-configuration
  • /<tenant-id>/discovery/v2.0/keys
• ... while using HttpClient.DefaultProxy you will see 4 calls in fiddler:
  • /<tenant-id>/v2.0/.well-known/openid-configuration
  • /<tenant-id>/discovery/v2.0/keys
  • /common/discovery/instance?....
  • /<tenant-id>/oauth2/v2.0/token

This means that setting the proxy on BackchannelHttpHandler is not sufficient when using OIDC behind corporate proxy.