OAuth 学习(2) —— 自定义OAuth服务端(WCF REST数据访问控制)

上篇了解了如何调用 OAuth 授权来获取数据，本篇介绍如何开放OAuth授权，并控制服务端数据访问。
先看一下图：

这两天事太多，文章整理的断断续续

OK，步入正题，这里还是要借力：DevDefined.OAuth 框架。它提供了客户端访问，服务端管理Token的基础功能。

1.OAuthChannel
定义了服务端用户模型，OAuth的拦截器，OAuthWebServiceHostFactory(继承于WebServiceHostFactory，用于添加拦截器)，以及 RequestToken 和 AccessToken 保持在内存里的容器及存取类 (InMemoryTokenRepository，InMemoryTokenStore)

OAuthWebServiceHostFactory 添加拦截器，使用了 WebServiceHost2(Microsoft.ServiceModel.Web.dll 里，是 Microsoft 发布的WCF REST Starter Kit的一部分)
WebServiceHost2 重写了 ServiceHost 里OnOpening 方法添加拦截器。WebServiceHost2的源代码猛击这里
OAuthWebServiceHostFactory：

<pre class="csharp" name="code">using System;
using System.ServiceModel.Activation;
using System.ServiceModel.Web;
using Microsoft.ServiceModel.Web;
using DevDefined.OAuth.Provider;
using OAuthChannel.Repositories;

namespace OAuthChannel
{
    public class OAuthWebServiceHostFactory : WebServiceHostFactory
    {
        public IOAuthProvider OAuthProvider { get; set; }
        public ITokenRepository<OAuthChannel.Models.AccessToken> AccessTokenRepository { get; set; }

        protected override System.ServiceModel.ServiceHost CreateServiceHost(Type serviceType, Uri[] baseAddresses)
        {
            var serviceHost = new WebServiceHost2(serviceType, true, baseAddresses);
            var interceptor = new OAuthChannel.OAuthInterceptor(OAuthProvider, AccessTokenRepository);
            serviceHost.Interceptors.Add(interceptor);
            return serviceHost;
        }
    }
}</pre>

拦截器(OAuthInterceptor.cs)将请求的 OAuth (Request Header中) 转换成OAuthChannel.Models.AccessToken

public class AccessToken : TokenBase
{
	public string UserName { get; set; }
	public string[] Roles { get; set; }
	public DateTime ExpireyDate { get; set; }
}

2. OAuth WCF Rest Service
首先创建一个 WCF Rest Service：

定义一个基础数据模型，供Sample访问：

namespace OAuthWcfRestService
{
    public class Contact
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public string Email { get; set; }
        public string Owner { get; set; }
    }

    public class DataModel
    {
        public static List<Contact> Contacts;

        static DataModel()
        {
            Contacts = new List<Contact> {
              new Contact(){ Id=0, Name="Felix", Email="[e-mail]", Owner = "jane" },
              new Contact(){ Id=1, Name="Wendy", Email="[e-mail]", Owner = "jane"},
              new Contact(){ Id=2, Name="John", Email="[e-mail]", Owner = "john"},
              new Contact(){ Id=3, Name="Philip", Email="[e-mail]", Owner = "john"}
            };
        }
    }
}

Contacts 中的数据只有属于 Owner 的“用户”才可以访问，因此 OAuthService 中实现如下：

namespace OAuthWcfRestService
{
    [ServiceContract]
    [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
    [ServiceBehavior(InstanceContextMode = InstanceContextMode.PerCall)]
    public class OAuthService
    {
        [WebGet(UriTemplate = "Contacts")]
        public List<Contact> Contacts()
        {
            var name = Thread.CurrentPrincipal.Identity.Name;
            return DataModel.Contacts.Where(c => c.Owner == name).ToList();
        }        
    }
}

上面的 name 从 Thread.CurrentPrincipal.Identity.Name 而来，即访问当前服务的客户端ID。这个ID是由OAuth服务的拦截器(Interceptor)实现由 AccessToken(String) 转换成服务端用户模型。

在 web.config 中，利用 WCF 对 ASP.NET 的兼容机制，使用 Form 认证：定义了两个用户：john 和 jane

<system.web>
  <compilation debug="true" targetFramework="4.0" />
  <authentication mode="Forms">
    <forms loginUrl="Pages/Login.aspx" cookieless="UseUri">
      <credentials passwordFormat="Clear">
        <user name="john" password="password"/>
        <user name="jane" password="password"/>
      </credentials>
    </forms>
  </authentication>
  <authorization>
    <allow users="*"/>
  </authorization>
</system.web>

并修改 Global.asax 的 WebServiceHostFactory，改为OAuthWebServiceHostFactory

public class Global : HttpApplication
{
    void Application_Start(object sender, EventArgs e)
    {
        RegisterRoutes();
    }

    private void RegisterRoutes()
    {
        var oauthWebServiceHostFactory = new OAuthChannel.OAuthWebServiceHostFactory 
        { 
              AccessTokenRepository = OAuthServicesLocator.AccessTokenRepository,
              OAuthProvider = OAuthServicesLocator.Provider 
        };
        RouteTable.Routes.Add(new ServiceRoute("OAuthService", oauthWebServiceHostFactory, typeof(OAuthService)));
    }
}

作为一个基本的OAuth授权服务，我们还需要提供：
1. 获取 RequestToken 的服务
2. 获取 AccessToken 的服务
RequestToken.ashx ：返回 RequestToken

<pre class="csharp" name="code">using System;
using System.Web.UI;
using DevDefined.OAuth.Framework;
using DevDefined.OAuth.Provider;

namespace OAuthWcfRestService
{
    public partial class RequestToken : System.Web.IHttpHandler
    {
        public bool IsReusable
        {
            get { return true; }
        }

        public void ProcessRequest(System.Web.HttpContext context)
        {
            IOAuthContext oauthContext = new OAuthContextBuilder().FromHttpRequest(context.Request);
            IOAuthProvider provider = OAuthManager.Provider;
            IToken token = provider.GrantRequestToken(oauthContext);
            context.Response.Write(token);
            context.Response.End();
        }
    }
}</pre>

AccessToken.ashx ：交换 RequestToken 返回 AccessToken

using System;
using System.Web.UI;
using DevDefined.OAuth.Framework;
using DevDefined.OAuth.Provider;

namespace OAuthWcfRestService
{
    public partial class AccessToken : System.Web.IHttpHandler
    {
        public bool IsReusable
        {
            get { return true; }
        }

        public void ProcessRequest(System.Web.HttpContext context)
        {
            IOAuthContext oauthContext = new OAuthContextBuilder().FromHttpRequest(context.Request);
            IOAuthProvider provider = OAuthManager.Provider;
            IToken accessToken = provider.ExchangeRequestTokenForAccessToken(oauthContext);
            context.Response.Write(accessToken);
            context.Response.End();
        }
    }
}

当然我们还需要提供用户登录和授权的页面：Login.aspx 和 UserAuthorize.aspx Form登录就不累述了， UserAuthorize.aspx 中实现授权的方法如下：

private void ApproveRequestForAccess(string tokenString)
{           
    OAuthChannel.Models.RequestToken requestToken = RequestTokenRepository.GetToken(tokenString);
    var accessToken = new OAuthChannel.Models.AccessToken
                          {
                              ConsumerKey = requestToken.ConsumerKey,
                              Realm = requestToken.Realm,
                              Token = Guid.NewGuid().ToString(),
                              TokenSecret = Guid.NewGuid().ToString(),
                              UserName = HttpContext.Current.User.Identity.Name,
                              ExpireyDate = DateTime.Now.AddMinutes(1),
                              Roles = new string[] { }
                          };
    AccessTokenRepository.SaveToken(accessToken);
    requestToken.AccessToken = accessToken;
    RequestTokenRepository.SaveToken(requestToken);
}

3. 应用

Default.aspx 发起请求获取RequestToken，授权成功后回调 Callback.ashx

namespace OAuthConsumerSample
{
    public partial class _Default : Page
    {
        protected void oauthRequest_Click(object sender, EventArgs e)
        {
	    OAuthSession session = OAuthSessionFactory.CreateSession();
            IToken requestToken = session.GetRequestToken();
            if (string.IsNullOrEmpty(requestToken.Token))
            {
                throw new Exception("The request token was null or empty");
            }
            Session[requestToken.Token] = requestToken;
            string callBackUrl = "http://localhost:" + HttpContext.Current.Request.Url.Port + "/Callback.ashx";
            string authorizationUrl = session.GetUserAuthorizationUrlForToken(requestToken, callBackUrl);
            Response.Redirect(authorizationUrl, true);
        }
    }
}

Callback.ashx

namespace OAuthConsumerSample
{
    public partial class Callback : System.Web.IHttpHandler, System.Web.SessionState.IRequiresSessionState
    {
        public void ProcessRequest(System.Web.HttpContext context)
        {
            var session = OAuthSessionFactory.CreateSession();
            string requestTokenString = context.Request["oauth_token"];
            var requestToken = (IToken)context.Session[requestTokenString];
            IToken accessToken = session.ExchangeRequestTokenForAccessToken(requestToken);
            context.Session[requestTokenString] = null;
            context.Session[accessToken.Token] = accessToken;
            context.Response.Redirect("ViewData.ashx?oauth_token=" + accessToken.Token);
        }

        public bool IsReusable
        {
            get { return true; }
        }
    }
}