Multipart form+file upload

NetworkUtil.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net;
using System.IO;
using System.Collections.Specialized;
using System.Diagnostics;

namespace Util
{
    using Newtonsoft.Json;

    /// <summary>
    /// misc network utils
    /// </summary>
    public class NetworkUtil
    {

        /// <summary>
        /// The http upload file.
        /// </summary>
        /// <param name="url"> The url. </param>
        /// <param name="file"> The file. </param>
        /// <param name="fileStream"> The file stream. </param>
        /// <param name="paramName"> The file param name. </param>
        /// <param name="contentType"> The content type. </param>
        /// <param name="nvc"> The nvc. </param>
        /// <returns> The <see cref="Stream"/>. </returns>
        public static T HttpUploadFile<T, TError>(string url, string file, Stream fileStream, string paramName, string contentType, NameValueCollection nvc, IServerConnector connector) where T : JsonBaseResult
        {
            Stream stm = null;
            while (true)
            {
                try
                {
                    stm = PerformUpload(url, file, fileStream, paramName, contentType, nvc, connector);
                    break;
                }
                catch (WebException we)
                {
                    if ((we.Response as HttpWebResponse).StatusCode == HttpStatusCode.Unauthorized)
                    {
                        connector.ResetSession();
                        continue; // retry
                    }
                    else
                    {
                        throw;
                    }
                }
                catch (Exception)
                {
                    throw;
                }
            }

            JsonSerializer js = new JsonSerializer();
            var gcr = js.Deserialize<T>(new JsonTextReader(new StreamReader(stm)));
            if (!gcr.success)
            {
                stm.Seek(0, SeekOrigin.Begin);
                var err = js.Deserialize<TError>(new JsonTextReader(new StreamReader(stm)));
                throw ExceptionFactory.Error(err);
            }
            return gcr;
        }

        private static Stream PerformUpload(string url, string file, Stream fileStream, string paramName, string contentType, NameValueCollection nvc, IServerConnector connector)
        {
            // log.Debug(string.Format("Uploading {0} to {1}", file, url));
            string boundary = "---------------------------" + DateTime.Now.Ticks.ToString("x");
            byte[] boundarybytes = System.Text.Encoding.ASCII.GetBytes("\r\n--" + boundary + "\r\n");

            var wr = (HttpWebRequest)WebRequest.Create(url);
            wr.ContentType = "multipart/form-data; boundary=" + boundary;
            wr.Method = "POST";
            wr.KeepAlive = true;
            wr.CookieContainer = connector.CookieContainer;

            var credential = connector.Credentials;
            if (credential is UsernamePasswordCredential)
            {
                var upc = credential as UsernamePasswordCredential;
                wr.Headers.Add(
                    "Authorization",
                    "Basic "
                    +
                    Convert.ToBase64String(Encoding.UTF8.GetBytes(upc.Username + ":" + upc.Password.ToUnsecureString())));
            }
            else if (credential is CurrentWindowsIdentityCredential)
            {
                wr.UseDefaultCredentials = true;
            }
            else
            {
                throw new ArgumentException(String.Format("Unknow credential type {0}", credential));
            }

            wr.Credentials = System.Net.CredentialCache.DefaultCredentials;


            Stream rs = wr.GetRequestStream();

            string formdataTemplate = "Content-Disposition: form-data; name=\"{0}\"\r\n\r\n{1}";
            foreach (string key in nvc.Keys)
            {
                rs.Write(boundarybytes, 0, boundarybytes.Length);
                string formitem = string.Format(formdataTemplate, key, nvc[key]);
                byte[] formitembytes = System.Text.Encoding.UTF8.GetBytes(formitem);
                rs.Write(formitembytes, 0, formitembytes.Length);
            }

            byte[] buffer = new byte[4096];
            int bytesRead = 0;
            if (fileStream != null)
            {
                rs.Write(boundarybytes, 0, boundarybytes.Length);

                string headerTemplate =
                    "Content-Disposition: form-data; name=\"{0}\"; filename=\"{1}\"\r\nContent-Type: {2}\r\n\r\n";
                string header = string.Format(headerTemplate, paramName, file, contentType);
                byte[] headerbytes = System.Text.Encoding.UTF8.GetBytes(header);
                rs.Write(headerbytes, 0, headerbytes.Length);

                //FileStream fileStream = new FileStream(file, FileMode.Open, FileAccess.Read);
                fileStream.Seek(0, SeekOrigin.Begin);
                while ((bytesRead = fileStream.Read(buffer, 0, buffer.Length)) != 0)
                {
                    rs.Write(buffer, 0, bytesRead);
                }
                fileStream.Close();
            }

            byte[] trailer = System.Text.Encoding.ASCII.GetBytes("\r\n--" + boundary + "--\r\n");
            rs.Write(trailer, 0, trailer.Length);
            rs.Close();

            WebResponse wresp = null;
            try
            {
                wresp = wr.GetResponse();
                Stream stream2 = wresp.GetResponseStream();
                MemoryStream resp = new MemoryStream();
                while ((bytesRead = stream2.Read(buffer, 0, buffer.Length)) != 0)
                {
                    resp.Write(buffer, 0, bytesRead);
                }
                if (wresp.ContentLength != -1)
                {
                    Debug.Assert(resp.Length == wresp.ContentLength);
                }
                resp.Seek(0, SeekOrigin.Begin);
                return resp;
                //log.Debug(string.Format("File uploaded, server response is: {0}", reader2.ReadToEnd()));
            }
            catch (Exception ex)
            {
                log.Error("Error uploading file", ex);

            }
            finally
            {
                if (wresp != null)
                {
                    wresp.Close();
                    wresp = null;
                }
                wr = null;
            }
        }

    }
}