以下是客户端代码不可更改，只能操作服务端，C#服务端如何获取到 ris 或者buffer 值 ，对C#一块才开始学，求详细写法，在api接口中如何接收获取

Dim request As HttpWebRequest = HttpWebRequest.Create(url)
request.Method = HttpEnum.method_post
request.ContentType = HttpEnum.application_octet_stream
request.ContentLength = buffer.Length
request.KeepAlive = True
request.Timeout = 30 * 1000

Dim ris As Stream = request.GetRequestStream()
ris.Write(buffer, 0, buffer.Length)
ris.Flush()
ris.Close()