基于C#后台调用跨域MVC服务及带Cookie验证的实现

背景
随着富客户端框架的盛行，以及众多优秀的前端js框架，很多情况我们会遇到跨域的问题，而js的ajax请求是不允许直接跨域访问的，当然你会说可以用JSONP等，但是由于代码洁癖，不想在前端和后台添加callback，而且很多情况你是无法控制的，需要牵连考虑太多的情况。

所以我直接绕过了，每个前端应用，自带一个通用后端服务代理，该服务解决跨域问题，自动代理帮前台获取跨域的数据。

如何算跨域
虽然是个老问题，但是还是要提醒注意下两点：同IP，不同端口，数据访问是跨域的，但是Cookie访问是可以的（这个让我很难理解）

解决，源码

CookieContainer cookieContainer = new CookieContainer();

[HttpPost]
        public string CommonPost(string url)
        {
            log.Info(CookieHelper.GetCookie("ITDC_UserName") + "进入方法CommonPost Url=" + url);
            Uri address = new Uri(System.Configuration.ConfigurationManager.AppSettings["RESTfulAPI"].ToString() + url);
            HttpWebRequest request = WebRequest.Create(address) as HttpWebRequest;
            request.Method = "POST";
            request.ContentType = "application/x-www-form-urlencoded";
//远程服务,需要加入cookie验证
            cookieContainer.Add(address, GetCookie("ITDC_UserName"));
            cookieContainer.Add(address, GetCookie("ITDC_UserRole"));
            request.CookieContainer = cookieContainer;
            StringBuilder data = new StringBuilder();
            for (int i = 0; i < Request.QueryString.Count; i++)
            {
                if (Request.QueryString.Keys[i].ToString() == "url") continue;
                data.Append("&" + Request.QueryString.Keys[i].ToString() + "=" + Request.QueryString[i].ToString());
            }
            // Create a byte array of the data we want to send
            byte[] byteData = UTF8Encoding.UTF8.GetBytes(data.ToString().TrimStart('&'));
            // Set the content length in the request headers
            request.ContentLength = byteData.Length;
            // Write data 
            using (Stream postStream = request.GetRequestStream())
            {
                postStream.Write(byteData, 0, byteData.Length);
            } 
            string result = "";
            using (HttpWebResponse response = request.GetResponse() as HttpWebResponse)
            {
                StreamReader reader = new StreamReader(response.GetResponseStream());
                result = reader.ReadToEnd();
            }
            log.Info(CookieHelper.GetCookie("ITDC_UserName") + " 执行完成 CommonPost Url=" + url);
            return (result);
        }

前台调用

Ext.Ajax.request({url: APIUrl + '/Nebula/CommonPost?url=/Nebula/PostComment/&KlId=1&Msg=ok&Author=admin&Title=文章标题',
                  method: "POST",
                  success: function (response) {
                              Ext.Viewport.unmask();
                              var obj = Ext.decode(response.responseText);
                              Ext.Msg.alert("提示", obj.Msg, Ext.emptyFn);
                           },
                  failure: function (response) {
                              Ext.Viewport.unmask();
                              Ext.Msg.alert("提示", "操作失败，请检查网络！", Ext.emptyFn);
                           }
});