Unhandled case: renewal fails because the token is too old

[pjt33]

I had an unhandled exception when calling PersistentAuthHelper.GetToken(string id, string resource) to log into an Azure subscription which I hadn't accessed in a very long time. Unfortunately I didn't document the details (or locate and back up the token cache) before trying a workaround, but the gist was that BaseAuthHelper.GetTokenInternal went into the case

ARMClient/ARMClient.Authentication/AADAuthentication/BaseAuthHelper.cs

Line 318 in 3dc4ff9

if (cacheInfo.ExpiresOn <= DateTimeOffset.UtcNow)

which called

ARMClient/ARMClient.Authentication/AADAuthentication/BaseAuthHelper.cs

Line 442 in 3dc4ff9

return await GetAuthorizationResultByRefreshToken(tokenCache, cacheInfo);

and that threw an exception on receiving an HTTP 400 response because the refresh token was too old.

A workaround is to change

ARMClient/ARMClient.Authentication/AADAuthentication/BaseAuthHelper.cs

Line 257 in 3dc4ff9

if (ex.Message.IndexOf(" is expired") < 0)

to

                if (ex.Message.IndexOf(" is expired") < 0 && ex.Message.IndexOf(" has expired") < 0)

but I suspect that a better solution would be to rework the logic of GetTokenInternal so that it treats a cache entry older than some cutoff (90 days?) as non-existent.