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);
                           }
});