public async Task <IActionResult> Callback(string returnUrl)
{
if (string.IsNullOrEmpty(returnUrl))
{
returnUrl = "~/";
}
;
// Validate returnUrl - either it is a valid OIDC URL or back to a local page.
if (Url.IsLocalUrl(returnUrl) == false && _interaction.IsValidReturnUrl(returnUrl) == false)
{
// User might have clicked on a malicious link - should be logged.
throw new Exception("Invalid return URL.");
}
// Read external identity from the temporary cookie.
// At this point registered claims transformation will run (the ClaimsTransformer class).
// This is triggered when HttpContext.AuthenticateAsync method is called (which is done inside GetExternalLoginInfoAsync method of SignInManager).
var externalLoginInfo = await _signInManager.GetExternalLoginInfoAsync();
if (externalLoginInfo == null)
{
throw new Exception($"Cannot read external login information from {externalLoginInfo.LoginProvider}.");
}
var user = await _userManager.FindByLoginAsync(externalLoginInfo.LoginProvider, externalLoginInfo.ProviderKey);
// If user with the specified login is null, this means that we have to do with a brand new user.
if (user == null)
{
// Retrieve claims of the external user.
var claims = externalLoginInfo.Principal.Claims.ToList();
// We can choose to auto-provision the user or initiate a custom workflow for user registration.
user = await AutoProvisionExternalUserAsync(Guid.NewGuid().ToString(), claims);
// Save user external login.
await _userManager.AddLoginAsync(user, externalLoginInfo);
}
await _events.RaiseAsync(new UserLoginSuccessEvent(externalLoginInfo.LoginProvider, externalLoginInfo.Principal.GetSubjectId(), user.Id, user.UserName));
// Save user tokes retrieved from external provider.
await _signInManager.UpdateExternalAuthenticationTokensAsync(externalLoginInfo);
await _signInManager.ExternalLoginSignInAsync(externalLoginInfo.LoginProvider, externalLoginInfo.ProviderKey, isPersistent : true);
// Check if external login is in the context of an OIDC request.
var context = await _interaction.GetAuthorizationContextAsync(returnUrl);
if (context != null && 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));
}
