不同颁发者的 ASP 网络核心身份验证

Question

问题来了。我需要实现逻辑以在运行时对不同发行者的用户进行身份验证。 （使用 Cognito 用户池）

ConfigureServices.cs：

             var schemaMap = services.GetAllAuthorizationSchemesFromDB();
            services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
                .AddJwtBearerForSchemes(schemaMap, IssuerTemplate);

            services.AddAuthorization(auth =>
            {
                var allSchemaNames = schemaMap.Keys.ToList();
                allSchemaNames.Add(JwtBearerDefaults.AuthenticationScheme);

                auth.AddPolicy("EXTERNAL", new AuthorizationPolicyBuilder()
                   .AddAuthenticationSchemes(allSchemaNames.ToArray())
                   .RequireAuthenticatedUser()
                   .Build());
            });


Extentions.cs:
public static AuthenticationBuilder AddJwtBearerForSchemes(this AuthenticationBuilder authBuilder, Dictionary<string, string> schemaIssuerMap, Func<string, string> IssuerTemplate)
        {
            foreach (var item in schemaIssuerMap)
            {
                authBuilder.AddJwtBearer(item.Key, options =>
                {
                    options.TokenValidationParameters = new TokenValidationParameters
                    {
                        ValidateIssuerSigningKey = true,
                        ValidateAudience = false,
                        ClockSkew = TimeSpan.Zero,
                        ValidIssuer = IssuerTemplate(item.Value)
                    };
                    options.Authority = IssuerTemplate(item.Value);
                });
            }
            authBuilder.AddPolicyScheme("EXTERNAL", "EXTERNAL", options =>
            {
                options.ForwardDefaultSelector = context =>
                {
                    string authorization = context.Request.Headers[HeaderNames.Authorization];
                    if (!string.IsNullOrEmpty(authorization))
                    {
                        if (authorization.StartsWith("Bearer ", StringComparison.OrdinalIgnoreCase))
                        {
                            var token = authorization.Substring("Bearer ".Length).Trim();

                            var jwtHandler = new JwtSecurityTokenHandler();
                            if (jwtHandler.CanReadToken(token))
                            {
                                var jwtToken = jwtHandler.ReadJwtToken(token);
                                var scheme = jwtToken.Issuer;
                                return scheme;
                            }
                        }
                    }

                    return JwtBearerDefaults.AuthenticationScheme;
                };
            });

            return authBuilder;
        }

根本没有找到有关 asp net core auth 的正确解释信息，所以我只是不明白它是如何工作的。 异常，尝试发送请求时： System.InvalidOperationException: 未指定 authenticationScheme，也未找到 DefaultChallengeScheme。

我错过了什么？