跨域请求被阻止：CORS 标头“Access-Control-Allow-Origin”缺失

Question

使用 Identity Server 3 我正在尝试按照 documentation 配置 CORS。当我执行GET 请求时，我可以看到在 Fiddler 中捕获的响应是正确的并且缺少 Access-Control-Allow-Origin 标头。

这是用于设置IdentityServerOptions 的代码：

public void Configuration(IAppBuilder app)
{
    var factory = InMemoryFactory.Create(
        clients: Clients.Get(),
        scopes: Scopes.Get());

    var viewOptions = new DefaultViewServiceOptions();
    viewOptions.Stylesheets.Add("/Content/site.css");
    viewOptions.Scripts.Add("/Content/logon.js");
    viewOptions.CacheViews = false;
    factory.ConfigureDefaultViewService(viewOptions);

    // This is where the CORS policy service is configured.
    var corsPolicyService = new DefaultCorsPolicyService();
    corsPolicyService.AllowAll = true;
    factory.CorsPolicyService = new Registration<ICorsPolicyService>(corsPolicyService);

    var userService = new LocalRegistrationUserService();
    factory.UserService = new Registration<IUserService>(resolver => userService);

    var options = new IdentityServerOptions
    {
        SiteName = "IdentityServer",
        SigningCertificate = this.certificateProvider.Certificate,
        Factory = factory,
        RequireSsl = true,

        // This is deprecated, but should still work according to the documentation.
        // However using or not using it makes no change.
        // CorsPolicy = CorsPolicy.AllowAll,

        ProtocolLogoutUrls = logoutUrls,
        AuthenticationOptions = new AuthenticationOptions()
        {
            EnableSignOutPrompt = false,
            EnablePostSignOutAutoRedirect = true,
            PostSignOutAutoRedirectDelay = 5,                     
        },   
    };

    app.Map("/core", idsrvApp =>
    {
        idsrvApp.UseIdentityServer(options);
    });
}

如果我随后从其他站点发出简单的GET 请求，我得到的响应如下：

HTTP/1.1 302 Found
Content-Length: 0
Location: https://federation.example.com/core/login?signin=2ce0b4f...71313af
Server: Microsoft-IIS/8.5
Set-Cookie: SignInMessage.2ce0b4f...A1D5NkPJQ; path=/core; secure; HttpOnly
X-Powered-By: ASP.NET
Date: Mon, 13 Jul 2015 12:00:00 GMT

为什么没有应用 Access-Control-Allow-Origin 标头？

Answer 1

似乎在 Identity Server 3 中正确设置了 CORS 策略服务，但所请求的路径明确不可用通过不同的服务器。

由日志表中的错误标识的请求路径是：

对路径提出的 CORS 请求：/connect/authorize from origin: null 但由于 CORS 路径无效而被拒绝

我认为这是作为一种额外的安全措施，以防止恶意系统在未经用户同意的情况下登录用户。

因此，唯一可以调用此受保护路径的系统将在工厂的 Client.RedirectUris 中定义（对于隐式流）。