Startup.cs

// <copyright file="Startup.cs" company="Microsoft">
// Copyright (c) Microsoft. All Rights Reserved.
// </copyright>

namespace TeamsAuthSSO
{
    using System;
    using Microsoft.AspNetCore.Authentication.AzureAD.UI;
    using Microsoft.AspNetCore.Authentication.JwtBearer;
    using Microsoft.AspNetCore.Builder;
    using Microsoft.AspNetCore.Hosting;
    using Microsoft.Extensions.Configuration;
    using Microsoft.Extensions.DependencyInjection;
    using Microsoft.Extensions.Hosting;
    using Microsoft.IdentityModel.Tokens;    
    using TeamsTabSSO.Helper;

    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddControllersWithViews();
            services.AddHttpClient("WebClient", client => client.Timeout = TimeSpan.FromSeconds(600));
            services.AddHttpContextAccessor();
            services.AddAuthentication(options =>
                {
                    options.DefaultScheme = JwtBearerDefaults.AuthenticationScheme;
                })
                .AddJwtBearer(options =>
                {
                    var azureAdOptions = new AzureADOptions();
                    Configuration.Bind("AzureAd", azureAdOptions);
                    options.Authority = $"{azureAdOptions.Instance}{azureAdOptions.TenantId}/v2.0";
                    options.TokenValidationParameters = new TokenValidationParameters
                    {
                        ValidAudiences = SSOAuthHelper.GetValidAudiences(Configuration),
                        ValidIssuers = SSOAuthHelper.GetValidIssuers(Configuration),
                        AudienceValidator = SSOAuthHelper.AudienceValidator
                    };
                });
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");

                // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
                app.UseHsts();
            }

            app.UseHttpsRedirection();
            app.UseStaticFiles();

            app.UseRouting();

            app.UseAuthentication();
            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllerRoute(
                    name: "default",
                    pattern: "{controller=Home}/{action=Index}/{id?}");
            });
        }
    }
}