如何在客户端获取 DotNetOpenAuth.OAuth2 返回的错误消息？

Question

我正在使用ExchangeUserCredentialForToken 函数从授权服务器获取令牌。当我的用户存在于我的数据库中时，它工作正常，但是当凭据不正确时，我想向客户端发回一条消息。我正在使用以下 2 行代码来设置错误消息：

context.SetError("Autorization Error", "The username or password is incorrect!");
context.Rejected();

但在客户端我只收到协议错误（错误 400）。您能帮我如何在授权服务器上获取服务器端设置的错误消息吗？

来自授权服务器的完整应用配置：

using Constants;
using Microsoft.Owin;
using Microsoft.Owin.Security;
using Microsoft.Owin.Security.Cookies;
using Microsoft.Owin.Security.Infrastructure;
using Microsoft.Owin.Security.OAuth;
using Owin;
using System;
using System.Collections.Concurrent;
using System.Linq;
using System.Security.Claims;
using System.Security.Principal;
using System.Threading.Tasks;
using AuthorizationServer.Entities;
using AuthorizationServer.Entities.Infrastructure.Abstract;
using AuthorizationServer.Entities.Infrastructure.Concrete;

namespace AuthorizationServer
{
    public partial class Startup
    {
        private IEmployeeRepository Repository;  
        public void ConfigureAuth(IAppBuilder app)
        {
            //instanciate the repository
            Repository = new EmployeeRepository();

            // Enable Application Sign In Cookie
            app.UseCookieAuthentication(new CookieAuthenticationOptions
            {
                AuthenticationType = "Application",
                AuthenticationMode = AuthenticationMode.Passive,
                LoginPath = new PathString(Paths.LoginPath),
                LogoutPath = new PathString(Paths.LogoutPath),
            });

            // Enable External Sign In Cookie
            app.SetDefaultSignInAsAuthenticationType("External");
            app.UseCookieAuthentication(new CookieAuthenticationOptions
            {
                AuthenticationType = "External",
                AuthenticationMode = AuthenticationMode.Passive,
                CookieName = CookieAuthenticationDefaults.CookiePrefix + "External",
                ExpireTimeSpan = TimeSpan.FromMinutes(5),
            });

            // Enable google authentication
            app.UseGoogleAuthentication();

            // Setup Authorization Server
            app.UseOAuthAuthorizationServer(new OAuthAuthorizationServerOptions
            {
                AuthorizeEndpointPath = new PathString(Paths.AuthorizePath),
                TokenEndpointPath = new PathString(Paths.TokenPath),
                ApplicationCanDisplayErrors = true,
#if DEBUG
                AllowInsecureHttp = true,
#endif
                // Authorization server provider which controls the lifecycle of Authorization Server
                Provider = new OAuthAuthorizationServerProvider
                {
                    OnValidateClientRedirectUri = ValidateClientRedirectUri,
                    OnValidateClientAuthentication = ValidateClientAuthentication,
                    OnGrantResourceOwnerCredentials = GrantResourceOwnerCredentials,
                    OnGrantClientCredentials = GrantClientCredetails
                },

                // Authorization code provider which creates and receives authorization code
                AuthorizationCodeProvider = new AuthenticationTokenProvider
                {
                    OnCreate = CreateAuthenticationCode,
                    OnReceive = ReceiveAuthenticationCode,
                },

                // Refresh token provider which creates and receives referesh token
                RefreshTokenProvider = new AuthenticationTokenProvider
                {
                    OnCreate = CreateRefreshToken,
                    OnReceive = ReceiveRefreshToken,
                }
            });

            // indicate our intent to use bearer authentication
            app.UseOAuthBearerAuthentication(new OAuthBearerAuthenticationOptions
            {
                AuthenticationType = "Bearer",
                AuthenticationMode = Microsoft.Owin.Security.AuthenticationMode.Active
            });
        }

        private Task ValidateClientRedirectUri(OAuthValidateClientRedirectUriContext context)
        {
            if (context.ClientId == Clients.Client1.Id)
            {
                context.Validated(Clients.Client1.RedirectUrl);
            }
            else if (context.ClientId == Clients.Client2.Id)
            {
                context.Validated(Clients.Client2.RedirectUrl);
            }
            return Task.FromResult(0);
        }

        private Task ValidateClientAuthentication(OAuthValidateClientAuthenticationContext context)
        {

            string clientname;
            string clientpassword;


            if (context.TryGetBasicCredentials(out clientname, out clientpassword) ||
                context.TryGetFormCredentials(out clientname, out clientpassword))
            {
                employee Employee = Repository.GetEmployee(clientname, clientpassword);

                if (Employee != null)
                {
                    context.Validated();
                }
                else
                {
                    context.SetError("Autorization Error", "The username or password is incorrect!");
                    context.Rejected();
                }
            }
            return Task.FromResult(0);
        }

        private Task GrantResourceOwnerCredentials(OAuthGrantResourceOwnerCredentialsContext context)
        {
            var identity = new ClaimsIdentity(new GenericIdentity(context.UserName, OAuthDefaults.AuthenticationType), context.Scope.Select(x => new Claim("urn:oauth:scope", x)));

            context.Validated(identity);

            return Task.FromResult(0);
        }

        private Task GrantClientCredetails(OAuthGrantClientCredentialsContext context)
        {
            var identity = new ClaimsIdentity(new GenericIdentity(context.ClientId, OAuthDefaults.AuthenticationType), context.Scope.Select(x => new Claim("urn:oauth:scope", x)));

            context.Validated(identity);

            return Task.FromResult(0);
        }


        private readonly ConcurrentDictionary<string, string> _authenticationCodes =
            new ConcurrentDictionary<string, string>(StringComparer.Ordinal);

        private void CreateAuthenticationCode(AuthenticationTokenCreateContext context)
        {
            context.SetToken(Guid.NewGuid().ToString("n") + Guid.NewGuid().ToString("n"));
            _authenticationCodes[context.Token] = context.SerializeTicket();
        }

        private void ReceiveAuthenticationCode(AuthenticationTokenReceiveContext context)
        {
            string value;
            if (_authenticationCodes.TryRemove(context.Token, out value))
            {
                context.DeserializeTicket(value);
            }
        }

        private void CreateRefreshToken(AuthenticationTokenCreateContext context)
        {
            context.SetToken(context.SerializeTicket());
        }

        private void ReceiveRefreshToken(AuthenticationTokenReceiveContext context)
        {
            context.DeserializeTicket(context.Token);
        }
    }
}

Answer 1

经过数小时的网络搜索和阅读 blob 以及 owin 文档，我找到了一种方法，可以在登录尝试失败时返回 401。

我意识到在下面添加标头有点麻烦，但我找不到任何方法来读取 IOwinContext.Response.Body 流以查找错误消息。

首先，在OAuthAuthorizationServerProvider.GrantResourceOwnerCredentials 中我使用了SetError() 并在响应中添加了Headers

context.SetError("Autorization Error", "The username or password is incorrect!");
context.Response.Headers.Add("AuthorizationResponse", new[] { "Failed" });

现在，您可以区分身份验证请求失败的 400 错误和其他原因导致的 400 错误。

下一步是创建一个继承OwinMiddleware 的类。此类检查传出响应，如果 StatusCode == 400 和上面的 Header 存在，它将 StatucCode 更改为 401。

public class InvalidAuthenticationMiddleware : OwinMiddleware
{
    public InvalidAuthenticationMiddleware(OwinMiddleware next) 
        : base(next)
    {
    }

    public override async Task Invoke(IOwinContext context)
    {
        await Next.Invoke(context);

        if (context.Response.StatusCode == 400 && context.Response.Headers.ContainsKey("AuthorizationResponse"))
        {
            context.Response.Headers.Remove("AuthorizationResponse");
            context.Response.StatusCode = 401;
        }
    }
}

最后要做的是在您的Startup.Configuration 方法中，注册您刚刚创建的类。我在方法中执行任何其他操作之前注册了它。

app.Use<InvalidAuthenticationMiddleware>();

Answer 2

这是一个完整的解决方案，将 Jeff 的概念与我的原始帖子结合使用。

1) 在上下文中设置错误消息

如果您在设置错误消息后调用 context.Rejected()，则会删除错误消息（参见下面的示例）：

    context.SetError("Account locked", 
             "You have exceeded the total allowed failed logins.  Please try back in an hour.");
    context.Rejected();

您将希望从您的任务中删除 context.Rejected()。请注意 Rejected 和 SetError 方法的定义是：

拒绝：

将此上下文标记为未经应用程序验证。 IsValidated 和 HasError 作为调用的结果变为 false。

设置错误：

将此上下文标记为未经应用程序验证并分配各种错误信息属性。由于调用，HasError 变为 true，IsValidated 变为 false。

同样，通过在设置错误后调用 Rejected 方法，上下文将被标记为没有错误并且错误消息将被删除。

2) 设置响应的状态码： 使用 Jeff 的例子，稍微转一下。

我将创建一个全局属性来设置状态代码的标记，而不是使用魔术字符串。在您的静态全局类中，创建一个用于标记状态代码的属性（我使用了 X-Challenge，但您当然可以使用您选择的任何内容。）这将用于标记响应中添加的标头属性。

public static class ServerGlobalVariables
{
//Your other properties...
public const string OwinChallengeFlag = "X-Challenge";
}

然后在您的 OAuthAuthorizationServerProvider 的各种任务中，您将添加标签作为响应中新标头值的键。将 HttpStatusCode 枚举与全局标志结合使用，您将可以访问所有各种状态代码，并且避免使用魔术字符串。

//Set the error message
context.SetError("Account locked", 
        "You have exceeded the total allowed failed logins.  Please try back in an hour.");

//Add your flag to the header of the response
context.Response.Headers.Add(ServerGlobalVariables.OwinChallengeFlag, 
         new[] { ((int)HttpStatusCode.Unauthorized).ToString() }); 

在客户OwinMiddleware中，可以使用全局变量在header中搜索flag：

//This class handles all the OwinMiddleware responses, so the name should 
//not just focus on invalid authentication
public class CustomAuthenticationMiddleware : OwinMiddleware
{
    public CustomAuthenticationMiddleware(OwinMiddleware next)
        : base(next)
    {
    }

    public override async Task Invoke(IOwinContext context)
    {
        await Next.Invoke(context);

        if (context.Response.StatusCode == 400 
            && context.Response.Headers.ContainsKey(
                      ServerGlobalVariables.OwinChallengeFlag))
        {
            var headerValues = context.Response.Headers.GetValues
                  (ServerGlobalVariables.OwinChallengeFlag);

            context.Response.StatusCode = 
                   Convert.ToInt16(headerValues.FirstOrDefault());

            context.Response.Headers.Remove(
                   ServerGlobalVariables.OwinChallengeFlag);
        }         

    }
}

最后，正如 Jeff 所指出的，您必须在您的 Startup.Configuration 或 Startup.ConfigureAuth 方法中注册此自定义 OwinMiddleware：

app.Use<CustomAuthenticationMiddleware>();

使用上述解决方案，您现在可以设置状态代码和自定义错误消息，如下所示：

• 用户名或密码无效
• 此帐户已超过最大尝试次数
• 邮箱账户未确认

3) 从 ProtocolException 中提取错误信息

在客户端应用程序中，需要捕获和处理 ProtocolException。这样的事情会给你答案：

//Need to create a class to deserialize the Json
//Create this somewhere in your application
public class OAuthErrorMsg
    {
        public string error { get; set; }
        public string error_description { get; set; }
        public string error_uri { get; set; }
    }

 //Need to make sure to include Newtonsoft.Json
 using Newtonsoft.Json;

 //Code for your object....

 private void login()
    {
        try
        {
            var state = _webServerClient.ExchangeUserCredentialForToken(
                this.emailTextBox.Text, 
                this.passwordBox.Password.Trim(), 
                scopes: new string[] { "PublicProfile" });

            _accessToken = state.AccessToken;
            _refreshToken = state.RefreshToken;
        }
        catch (ProtocolException ex)
        {
            var webException = ex.InnerException as WebException;

            OAuthErrorMsg error = 
                JsonConvert.DeserializeObject<OAuthErrorMsg>(
                ExtractResponseString(webException));

            var errorMessage = error.error_description;
            //Now it's up to you how you process the errorMessage
        }
    }

    public static string ExtractResponseString(WebException webException)
    {
        if (webException == null || webException.Response == null)
            return null;

        var responseStream = 
            webException.Response.GetResponseStream() as MemoryStream;

        if (responseStream == null)
            return null;

        var responseBytes = responseStream.ToArray();

        var responseString = Encoding.UTF8.GetString(responseBytes);
        return responseString;
    }

我已经对此进行了测试，它在 VS2013 Pro 4.5 中完美运行！！

（请注意，我没有包含所有必要的命名空间或附加代码，因为这会因应用程序而异：WPF、MVC 或 Winform。另外，我没有讨论错误处理，所以你会想要确保在整个解决方案中实施正确的错误处理。）

Answer 3

Jeff 的解决方案对我不起作用，但是当我使用 OnSendingHeaders 时它可以正常工作：

public class InvalidAuthenticationMiddleware : OwinMiddleware
{
    public InvalidAuthenticationMiddleware(OwinMiddleware next) : base(next) { }

    public override async Task Invoke(IOwinContext context)
    {
        context.Response.OnSendingHeaders(state =>
        {
            var response = (OwinResponse)state;

            if (!response.Headers.ContainsKey("AuthorizationResponse") && response.StatusCode != 400) return;

            response.Headers.Remove("AuthorizationResponse");
            response.StatusCode = 401;

        }, context.Response);

        await Next.Invoke(context);
    }
}