public async Task <IHttpActionResult> GetExternalLogin(string provider, string error = null) { if (error != null) { return(Redirect(Url.Content("~/") + "#error=" + Uri.EscapeDataString(error))); } if (!User.Identity.IsAuthenticated) { return(new ChallengeResult(provider, this)); } ExternalLoginData externalLogin = ExternalLoginData.FromIdentity(User.Identity as ClaimsIdentity); if (externalLogin == null) { return(InternalServerError()); } if (externalLogin.LoginProvider != provider) { Authentication.SignOut(DefaultAuthenticationTypes.ExternalCookie); return(new ChallengeResult(provider, this)); } DeCamaroong.Domain.User user = await UserManager.FindAsync(new UserLoginInfo(externalLogin.LoginProvider, externalLogin.ProviderKey)); bool hasRegistered = user != null; if (hasRegistered) { Authentication.SignOut(DefaultAuthenticationTypes.ExternalCookie); ClaimsIdentity oAuthIdentity = await user.GenerateUserIdentityAsync(UserManager, OAuthDefaults.AuthenticationType); ClaimsIdentity cookieIdentity = await user.GenerateUserIdentityAsync(UserManager, CookieAuthenticationDefaults.AuthenticationType); AuthenticationProperties properties = ApplicationOAuthProvider.CreateProperties(user.UserName); Authentication.SignIn(properties, oAuthIdentity, cookieIdentity); } else { IEnumerable <Claim> claims = externalLogin.GetClaims(); ClaimsIdentity identity = new ClaimsIdentity(claims, OAuthDefaults.AuthenticationType); Authentication.SignIn(identity); } return(Ok()); }