Startup.Auth.cs

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Copyright (c) 2015 Microsoft Corporation

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using Microsoft.IdentityModel.Clients.ActiveDirectory;
using Microsoft.IdentityModel.Tokens;
using Microsoft.Owin.Security;
using Microsoft.Owin.Security.Cookies;
using Microsoft.Owin.Security.OpenIdConnect;
using Owin;
using System;
using System.Collections.Generic;
using System.IdentityModel.Claims;
using System.Linq;
using System.Threading.Tasks;
using System.Web;
using TodoListWebApp.DAL;
using TodoListWebApp.Models;
using TodoListWebApp.Utils;

namespace TodoListWebApp
{
    public partial class Startup
    {
        private readonly string authority = AadInstance + "common";

        private TodoListWebAppContext db = new TodoListWebAppContext();

        public void ConfigureAuth(IAppBuilder app)
        {
            app.SetDefaultSignInAsAuthenticationType(CookieAuthenticationDefaults.AuthenticationType);

            app.UseCookieAuthentication(new CookieAuthenticationOptions { });

            app.UseOpenIdConnectAuthentication(
                new OpenIdConnectAuthenticationOptions
                {
                    ClientId = ClientId,
                    Authority = this.authority,
                    RedirectUri = RedirectUri,
                    PostLogoutRedirectUri = RedirectUri,
                    TokenValidationParameters = this.BuildTokenValidationParameters(),
                    Notifications = new OpenIdConnectAuthenticationNotifications()
                    {
                        RedirectToIdentityProvider = (context) =>
                        {
                            // This ensures that the address used for sign in and sign out is picked up dynamically from the request
                            // this allows you to deploy your app (to Azure Web Sites, for example)without having to change settings
                            // Remember that the base URL of the address used here must be provisioned in Azure AD beforehand.
                            string appBaseUrl = context.Request.Scheme + "://" + context.Request.Host + context.Request.PathBase + "/";
                            context.ProtocolMessage.RedirectUri = appBaseUrl;
                            context.ProtocolMessage.PostLogoutRedirectUri = appBaseUrl;
                            return Task.FromResult(0);
                        },
                        SecurityTokenValidated = (context) =>
                        {
                            // retrieve caller data from the incoming principal
                            string issuer = context.AuthenticationTicket.Identity.FindFirst("iss").Value;
                            string Upn = context.AuthenticationTicket.Identity.FindFirst(ClaimTypes.Name).Value;
                            string tenantId = context.AuthenticationTicket.Identity.FindFirst("http://schemas.microsoft.com/identity/claims/tenantid").Value;

                            if (
                                // the caller comes from an admin-consented, recorded issuer
                                (this.db.Tenants.FirstOrDefault(a => ((a.IssValue == issuer) && (a.AdminConsented))) == null)
                                // the caller is recorded in the db of users who went through the individual on-boarding
                                && (this.db.Users.FirstOrDefault(b => ((b.UPN == Upn) && (b.TenantID == tenantId))) == null)
                                )
                                // the caller was neither from a trusted issuer or a registered user - throw to block the authentication flow
                                throw new UnauthorizedAccessException("Please use the Sign-up link to sign -up for the ToDo list application.");

                            return Task.FromResult(0);
                        },
                        AuthorizationCodeReceived = (context) =>
                        {
                            var code = context.Code;
                            ClientCredential credential = new ClientCredential(ClientId, AppKey);
                            string tenantId = context.AuthenticationTicket.Identity.FindFirst("http://schemas.microsoft.com/identity/claims/tenantid").Value;
                            string signedInUserId = context.AuthenticationTicket.Identity.FindFirst(ClaimTypes.NameIdentifier).Value;

                            AuthenticationContext authContext = new AuthenticationContext(AadInstance + tenantId, new ADALTokenCache(signedInUserId));

                            // The following operation fetches a token for Microsoft graph and caches it in the token cache
                            AuthenticationResult result = authContext.AcquireTokenByAuthorizationCodeAsync(
                                code, new Uri(HttpContext.Current.Request.Url.GetLeftPart(UriPartial.Path)), credential, GraphResourceId).Result;

                            return Task.FromResult(0);
                        },
                        AuthenticationFailed = (context) =>
                        {
                            context.Response.Redirect("/Error/ShowError?signIn=true&errorMessage=" + context.Exception.Message);
                            context.HandleResponse(); // Suppress the exception
                            return Task.FromResult(0);
                        }
                    }
                });
        }

        private TokenValidationParameters BuildTokenValidationParameters()
        {
            TokenValidationParameters validationParameters = new TokenValidationParameters
            {
                // Since this is a multi-tenant app, you should ideally only accept users from a list of tenants that you want to.
                // * Instead of using the default validation (validating against a single issuer value, as we do in line of business apps), you can inject your own multi-tenant validation logic through a IssuerValidator.
                // * Or you can provide a static list of acceptable tenantIds, as detailed below
                // ValidIssuers = new List<string>()
                // {
                //     "https://sts.windows.net/6d9c0c36-c30e-442b-b60a-ca22d8994d14/",
                //     "https://sts.windows.net/f69b5f46-9a0d-4a5c-9e25-54e42bbbd4c3/",
                //     "https://sts.windows.net/fb674642-8965-493d-beee-2703caa74f9a/"
                // }
                ValidateIssuer = true,
                IssuerValidator = AadIssuerValidator.ValidateAadIssuer
            };

            // Here we store the tenantIds who've signed up for the app in a database. When the app has to validate, it builds a list of signed-up issuers from the database.
            List<String> validIssuers = this.db.Tenants.GroupBy(a => a.IssValue).Select(a => a.FirstOrDefault().IssValue).ToList();

            validationParameters.ValidIssuers = validIssuers;
            return validationParameters;
        }
    }
}