模拟post登录求解

[bakdfkuk]

想实现一个模拟登录，但是无论如何还是登录不到系统中，请各位高手帮哈忙，我的代码如下：

我用firebug查看了请求的数据如下：
post部分：
参数 application/x-www-form-urlencoded
－－－－－－－－－－－－－－－－－－－－－－－－－－－－
__VIEWSTATE /wEPDwULLTExNDY5NzI1NTRkZDxUq+DKozsyBkD5NwEXp3n8vlje
btnLogin
txtPwd 123
txtUserName admin

下面有一个提示源代码：__VIEWSTATE=%2FwEPDwULLTExNDY5NzI1NTRkZDxUq%2BDKozsyBkD5NwEXp3n8vlje&txtUserName=admin&btnLogin=&txtPwd=123

 string loginurl = "http://www.******.com/login.aspx";
            string postData = "__VIEWSTATE=%2FwEPDwULLTExNDY5NzI1NTRkZM0rikwJ7c5wXU5YQWwcCccBzYZE&txtUserName=admin&btnLogin=&txtPwd=123";  //这个是我根据post数据来弄的
            byte[] b = System.Text.Encoding.GetEncoding("gb2312").GetBytes(postData);
            wreq = HttpWebRequest.Create(loginurl) as HttpWebRequest ;
            wreq.ContentLength = b.Length;
            wreq.Method = "Post";
            wreq.CookieContainer = ck;
            wreq.ContentType = "text/html; charset=gb2312";
            wreq.KeepAlive = true;
            wreq.AllowAutoRedirect = true;
            wreq.Referer = "http://www.******.com/login.aspx";
            wreq.AllowWriteStreamBuffering = true;
            wreq.UserAgent = "Mozilla/5.0 (Windows NT 5.1; rv:8.0.1) Gecko/20100101 Firefox/8.0.1";

            Stream myRequestStream = wreq.GetRequestStream();
            using (StreamWriter myStreamWriter = new StreamWriter(myRequestStream, Encoding.GetEncoding("gb2312")))
            {
                myStreamWriter.Write(postData);
            }
            myRequestStream.Close();

            using( wres=(HttpWebResponse) wreq.GetResponse()) {
                     //wres.Cookies永远都是为0
                if (wres.Cookies.Count >0)
                {   
                         
                    ck.Add(wres.Cookies);
                }
                

                using (StreamReader reader = new StreamReader(wres.GetResponseStream(),System.Text.Encoding.UTF8)) {
                   
                    string aaa= reader.ReadToEnd();
                    Response.Write(aaa);  //这里得到的数据还是登录页面的，而不是进入系统的代码，

                }

            }

其它头信息如下：

响应头信息原始头信息
Cache-Control private
Content-Length 146
Content-Type text/html; charset=utf-8
Date Fri, 02 Mar 2012 12:30:54 GMT
Location /manage/AdminDefault.aspx
Server Microsoft-IIS/6.0
X-AspNet-Version 2.0.50727
X-Powered-By ASP.NET
请求头信息原始头信息
Accept text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Charset GB2312,utf-8;q=0.7,*;q=0.7
Accept-Encoding gzip, deflate
Accept-Language zh-cn,zh;q=0.5
Connection keep-alive
Cookie ASP.NET_SessionId=3y15jsbfuf4irj451megtayu; cnzz_a3162184=2; sin3162184=; rtime=0; ltime=1330688762546; cnzz_eid=32735649-1330674004-
Host www.******.com
Referer http://www.******.com/login.aspx
User-Agent Mozilla/5.0 (Windows NT 5.1; rv:8.0.1) Gecko/20100101 Firefox/8.0.1
来自缓存的响应头信息
Cache-Control private
Content-Length 146
Content-Type text/html; charset=utf-8
Date Fri, 02 Mar 2012 12:30:54 GMT
Location /manage/AdminDefault.aspx
Server Microsoft-IIS/6.0
X-AspNet-Version 2.0.50727
X-Powered-By ASP.NET
Request Headers From Upload Stream
Content-Length 107
Content-Type application/x-www-form-urlencoded



请高手帮帮忙

[newdigitime]

有些时候,登录并不是你想像的这么简单.

就算你正确无误地提交了各个参数,也不一定登录成功.因为
验证通过后,服务器会向客户端发送cookie数据.用于在cookie中保留登录信息.即使是SESSION,大多也需要在cookie中保存sessionID.
但你没有做到这一步,没有获取服务器返回的这些cookie包,并把cookie数据连同验证成功后,需要跳转的网址一起再次发给服务器.

[bakdfkuk]

我也想尽力获取到cookie，但经过wres.Cookies.Count 发现，数量总是为0，貌似获取不到的样子，我一步一步调试下来看到在： Stream myRequestStream = wreq.GetRequestStream();时就有异常了，但是很奇怪的是这个异常却还会使程序继续执行，而不中断，报的错误是：Length = “myRequestStream.Length”引发了“System.NotSupportedException”类型的异常，在网上找了一些资料，发现MSDN上是这么说的：



The request cache validator indicated that the response for this request can be served from the cache; however, requests that write data must not use the cache. This exception can occur if you are using a custom cache validator that is incorrectly implemented.


貌似有客户端是没有办法伪造一个cache，弄了好久，只看到网上有人模拟登录成功，但我却怎么弄都开不好，纠结

[bakdfkuk]

哇，高手们去哪里了？

[bdmh]

用户名和密码都是明文的吗，一般不会可能吧，都会经过加密传递给验证端的，如果你用明文参数，那肯定不行吧
而且 wreq 也没看见传递用户信息呢

[bakdfkuk]

明文是通过抓取获取的

[bakdfkuk]

感谢4楼给出的答案，虽然没有解决我的问题，不过却让我更明确理解了bs中一些东西，反复读了几遍http协议，呵呵