asp.net 實現一個簡單CAS Server

根據下圖所示,我們需要實現CASClient端得"攔截器",我們通過HttpModule實現,服務端需要兩個頁面,一個是登陸界面,一個途中第5步通過token獲取用戶信息的頁面或者ashx。
cas_protocol-1.jpg

1、客戶端的代碼和配置
新建一個類,代碼如下:
HttpModule
<!--

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--> 1 using System;
2 using System.Collections.Generic;
3 using System.Linq;
4 using System.Web;
5 using System.Web.SessionState;
6 using System.Text;
7 using System.Net;
8 using System.IO;
9
10 namespace client
11 {
12     public class filter : IHttpModule, IRequiresSessionState
13     {
14         string login_url = "http://localhost:10888/Default.aspx";
15         string verify_url = "http://localhost:10888/method.ashx";
16
17         public void Dispose()
18         {
19
20         }
21
22         public void Init(HttpApplication context)
23         {
24             context.PreRequestHandlerExecute += new EventHandler(context_PreRequestHandlerExecute);           
25         }
26
27         void context_PreRequestHandlerExecute(object sender, EventArgs e)
28         {
29             try
30             {
31                 HttpApplication ha = (HttpApplication)sender;
32
33                 HttpRequest Request = ha.Context.Request;
34                 HttpResponse Response = ha.Context.Response;
35
36                 string continue_url = Request.Url.AbsoluteUri;
37                 string path = ha.Context.Request.Url.AbsolutePath;
38
39
40                 string token = Request["token"];
41                 if (!string.IsNullOrEmpty(token)) //這次請求是從CAS登陸後跳轉而來
42                 {
43                     //使用POST連接CAS的method.ashx,通過token獲取用戶信息
44                     string res = Post(verify_url, "token=" + token, "utf-8");
45                     ha.Session["user"] = res;
46                     Response.Redirect(ha.Session["continue_url"].ToString());
47                 }
48
49                 if ((ha.Session == null) || (ha.Session["user"] == null)) //通過Session判斷登陸狀態
50                 {
51                     ha.Session["continue_url"] = continue_url;
52                     ha.Response.Redirect(login_url + "?continute_url=" + continue_url); //去登陸cas頁面
53                 }
54             }
55             catch (Exception ex)
56             {
57                 (sender as HttpApplication).Response.Write(ex.Message);
58             }
59         }
60
61         public string Post(string postUrl, string postData, string chars_set)
62         {
63             Encoding encoding = Encoding.GetEncoding(chars_set);
64             HttpWebRequest Request = (HttpWebRequest)WebRequest.Create(postUrl);
65             CookieContainer cookieContainer = new CookieContainer();
66             Request.CookieContainer = cookieContainer;
67             Request.Method = "POST";
68             Request.ContentType = "application/x-www-form-urlencoded";
69             Request.AllowAutoRedirect = true;
70             byte[] postdata = encoding.GetBytes(postData);
71             using (Stream newStream = Request.GetRequestStream())
72             {
73                 newStream.Write(postdata, 0, postdata.Length);
74             }
75             using (HttpWebResponse response = (HttpWebResponse)Request.GetResponse())
76             {
77                 using (Stream stream = response.GetResponseStream())
78                 {
79                     using (StreamReader reader = new StreamReader(stream, encoding, true))
80                     {
81                         return reader.ReadToEnd();
82                     }
83                 }
84             }
85         }
86     }
87 }
88
需要在攔截所有請求,在web.config中配置
<httpModules>
..............
<add name="LoginMoudle" type="client.filter"/> //type由於寫在項目中只需要namespace.class方式,如果放在dll中,需要加",dll文件名"
</httpModules>

2、CAS服務端代碼
1)登陸頁面
Code
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-->1     <form id="form1" runat="server" method="post" action="login.ashx">
2     <div>Login ID:<input type="text" id="loginid" name="loginid" /></div>
3     <div>Password:<input type="password" id="password" name="password" /></div>
4     <div><input type="hidden" id="continute_url" name="continute_url" value="<%=Request["continute_url"] %>"/></div>
5     <div><input type="submit" value="Login" /></div>
6     </form
其中continute_url是filer傳來的

2)登陸代碼
Login
<!--

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--> 1 using System;
2 using System.Collections.Generic;
3 using System.Linq;
4 using System.Web;
5 using System.Web.Services;
6
7 namespace cas
8 {
9     [WebService(Namespace = "http://tempuri.org/")]
10     [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
11     public class login : IHttpHandler
12     {
13
14         public void ProcessRequest(HttpContext context)
15         {
16             HttpRequest Request = context.Request;
17             string loginid = Request["loginid"];
18             string password = Request["password"];
19             string continute_url = Request["continute_url"];
20
21             //用戶登錄驗證.
22
23             string token = DateTime.Now.Ticks.ToString();//登陸成功後 生成token方法,自己考慮,需唯一
24             //緩存token
25             context.Application[token] = "用戶名"; //實際使用中存放用戶信息類的實例
26             //轉移
27             context.Response.Redirect(continute_url + "?token=" + token);
28         }
29
30         public bool IsReusable
31         {
32             get
33             {
34                 return false;
35             }
36         }
37     }
38 }
39

3)CAS端獲取用戶信息的頁面
method GetUser
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--> 1 public class method : IHttpHandler
2     {
3
4         public void ProcessRequest(HttpContext context)
5         {
6             string token = context.Request["token"];
7           
8             string user = context.Application[token].ToString(); //獲取token映射的用戶信息
9             context.Application.Remove(token); //刪除緩存的token,token一次有效
10            
11             context.Response.Write(user);//實際使用中可能需要返回xml或者json格式的用戶信息
12         }
13
14         public bool IsReusable
15         {
16             get
17             {
18                 return false;
19             }
20         }
21

運行過程基本是這樣的:用戶訪問網站,filer首先攔截判斷session中用戶信息,如果不爲空放行,否則,轉到CAS登陸界面,登陸界面登陸後,返回地址中夾帶token.
網站後臺通過get或者post方法使用token去獲取用戶信息。

最後網站程序通過Session["user"]獲取用戶信息,無需關心登陸的實現,這樣我們就實現了一個簡單單點登錄系統了。
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