例外：oauth 状态丢失或无效。（ASP.NET Core 外部标识符 OAuth）答案

【问题标题】：Exception: The oauth state was missing or invalid. (ASP.NET Core external identifier OAuth)例外：oauth 状态丢失或无效。（ASP.NET Core 外部标识符 OAuth）
【发布时间】：2021-04-26 11:59:26
【问题描述】：

我正在尝试在 Asp.Net Core (https://github.com/aspnet-contrib/AspNet.Security.OAuth.Providers) 中实现外部 OAuth。我的应用程序（GitLab）有回调 URL https://myhost.com/signin-gitlab（中间件默认使用）。

如果我运行下面的代码，我会收到“异常：oauth 状态丢失或无效”。但是，如果我从 Startup.cs 中删除“options.UserInformationEndpoint”，那么我会使用代码和状态参数重定向到 myhost.com/signin-gitlab，中间件应该用它们交换访问令牌。我的问题是，为什么我的状态参数会损坏（使用 UserInformationEndpoint）？为什么我没有获得访问令牌？我在这里错过了什么？

我的创业班：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Authentication.Cookies;
using Microsoft.AspNetCore.Authentication.OAuth;
using Microsoft.AspNetCore.Http;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.AspNetCore.Authentication.JwtBearer;
using AspNet.Security.OAuth.GitLab;
using System.Net.Http;
using System.Net.Http.Headers;

namespace MyApp
{
    public class Startup
    {
        private readonly IConfiguration _cfg;

        public Startup(IConfiguration configuration) => _cfg = configuration;

        public void ConfigureServices(IServiceCollection services)
        {
            services.AddRouting();

            services.AddAuthentication(CookieAuthenticationDefaults.AuthenticationScheme)
                    .AddCookie()
                    .AddGitLab("Gitlab", options => {
                        options.ClientId = "...";
                        options.ClientSecret = "...";

                        options.AuthorizationEndpoint = "https://mygitlabserver.com/oauth/authorize";
                        options.TokenEndpoint = "https://mygitlabserver.com/oauth/token";
                        options.Scope.Clear();
                        options.Scope.Add("api");
                        options.SaveTokens = true;

                        options.SignInScheme = CookieAuthenticationDefaults.AuthenticationScheme;
                        options.UserInformationEndpoint = "https://mygitlabserver.com/api/v4/user"; 
                    });

            services.AddMvc();

        }

        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            app.UseDeveloperExceptionPage();
            app.UseRouting();

            app.UseAuthentication();
            app.UseAuthorization();
               
            app.UseEndpoints(endpoints =>
            {
                endpoints.MapDefaultControllerRoute();
            });
        }
    }
}

我的控制器：

using System.Threading.Tasks;
using Microsoft.AspNetCore.Authentication;
using Microsoft.AspNetCore.Authentication.Cookies;
using Microsoft.AspNetCore.Mvc;

namespace MyApp.Controllers
{
    public class HomeController : Controller
    {
        [HttpGet("/")]
        public IActionResult Index()
        {
            return View();
        }

        [HttpGet("/login")]
        public IActionResult LogIn()
        {
            // Instruct the middleware corresponding to the requested external identity
            // provider to redirect the user agent to its own authorization endpoint.
            // Note: the authenticationScheme parameter must match the value configured in Startup.cs
            return Challenge(new AuthenticationProperties { RedirectUri = "https://myhost.com/signin-gitlab" }, "Gitlab");
        }   
    }
}

【问题讨论】：

标签： c# asp.net-core oauth-2.0 aspnet-contrib

【解决方案1】：

首先，ASP.NET 外部身份提供者/社交登录可以使用或不使用身份框架来完成。如果没有身份，它应该像这样设置（https://docs.microsoft.com/en-us/aspnet/core/security/authentication/social/social-without-identity?view=aspnetcore-5.0）：

public void ConfigureServices(IServiceCollection services)
{
    // requires
    // using Microsoft.AspNetCore.Authentication.Cookies;
    // using Microsoft.AspNetCore.Authentication.Google;
    // NuGet package Microsoft.AspNetCore.Authentication.Google
    services
        .AddAuthentication(options =>
        {
            options.DefaultScheme = CookieAuthenticationDefaults.AuthenticationScheme;
            options.DefaultChallengeScheme = GoogleDefaults.AuthenticationScheme;
        })
        .AddCookie()
        .AddGoogle(options =>
        {
            options.ClientId = Configuration["Authentication:Google:ClientId"];
            options.ClientSecret = Configuration["Authentication:Google:ClientSecret"];
        });

    services.AddRazorPages();
}

第二个问题是在控制器内部：

return Challenge(new AuthenticationProperties { RedirectUri = "https://myhost.com/signin-gitlab" }, "Gitlab");

正如 aspnet-contrib 团队 (https://github.com/aspnet-contrib/AspNet.Security.OAuth.Providers/blob/dev/samples/Mvc.Client/Controllers/AuthenticationController.cs) 在 MVC 示例应用程序中一样，它实际上应该是：

return Challenge(new AuthenticationProperties { RedirectUri = "/" }, "Gitlab");

用户实际上是经过身份验证的，问题是他们随后被重定向到 OAuth 中间件的内部路由 /signin-gitlab 没有状态或代码参数，而不是主路由/索引操作，因此出现错误。

换句话说，我搞混了：

RedirectUri（用户在身份验证后被重定向）
回调 URL（OAuth 应用程序将带有状态和代码的用户重定向到 OAuth 中间件内部路由，默认为 /signin-gitlab、/signin-google、/signin-facebook，但也可以使用选项覆盖.CallbackPath)。

也许我的困惑是因为回调 url 在 GitLab 文档 (https://docs.gitlab.com/ee/api/oauth2.html) 中称为 REDIRECT_URI。

感谢 Nan Yu (https://stackoverflow.com/a/61452853/2768479) 和 Tratcher (https://github.com/dotnet/aspnetcore/issues/22125, https://github.com/aspnet/Security/issues/1756) 的精彩帖子。

【讨论】：