public async Task <IActionResult> Callback() { // read external identity from the temporary cookie var result = await HttpContext.AuthenticateAsync(IdentityServer4.IdentityServerConstants.ExternalCookieAuthenticationScheme); if (result?.Succeeded != true) { throw new Exception("External authentication error"); } // lookup our user and external provider info var(user, provider, providerUserId, claims) = await _userValidator.FindUserFromExternalProviderAsync(result); if (user == null) { // this might be where you might initiate a custom workflow for user registration // in this sample we don't show how that would be done, as our sample implementation // simply auto-provisions new external user user = await _userValidator.AutoProvisionUserAsync(provider, providerUserId, claims); } // this allows us to collect any additonal claims or properties // for the specific prtotocols used and store them in the local auth cookie. // this is typically used to store data needed for signout from those protocols. var additionalLocalClaims = new List <Claim>(); var localSignInProps = new AuthenticationProperties(); ProcessLoginCallbackForOidc(result, additionalLocalClaims, localSignInProps); ProcessLoginCallbackForWsFed(result, additionalLocalClaims, localSignInProps); ProcessLoginCallbackForSaml2p(result, additionalLocalClaims, localSignInProps); // issue authentication cookie for user await _events.RaiseAsync(new UserLoginSuccessEvent(provider, providerUserId, user.Id, user.Email)); await HttpContext.SignInAsync(user.Id, user.Email, provider, localSignInProps, additionalLocalClaims.ToArray()); // delete temporary cookie used during external authentication await HttpContext.SignOutAsync(IdentityServer4.IdentityServerConstants.ExternalCookieAuthenticationScheme); // retrieve return URL var returnUrl = result.Properties.Items["returnUrl"] ?? "~/"; // check if external login is in the context of an OIDC request var context = await _interaction.GetAuthorizationContextAsync(returnUrl); if (context != null) { if (await _clientStore.IsPkceClientAsync(context.ClientId)) { // if the client is PKCE then we assume it's native, so this change in how to // return the response is for better UX for the end user. return(View("Redirect", new RedirectViewModel { RedirectUrl = returnUrl })); } } return(Redirect(returnUrl)); }