HttpHelper.cs

using System;
using System.Net;
using System.Collections.Specialized;
using System.IO;
using System.Collections.Generic;

namespace Core.Api.Http
{

        public class Credential {
            public String Username { get; set; }
            public String Password { get; set; }
        }
	
	public class HttpHelper
	{
		public static HttpResult HttpUploadFile (Credential credential, string url, string file, string paramName, string contentType, IDictionary<string,string> parameters)
		{
			string boundary = "my-drop-file-upload" + DateTime.Now.Ticks.ToString ("x");
			byte[] boundarybytes = System.Text.Encoding.ASCII.GetBytes ( "--" + boundary);

			HttpWebRequest httpRequest = (HttpWebRequest)WebRequest.Create (url);
			httpRequest.ContentType = "multipart/form-data; boundary=" + boundary;
			httpRequest.Method = "POST";
			httpRequest.KeepAlive = true;
			httpRequest.Credentials = System.Net.CredentialCache.DefaultCredentials;
			
			byte[] base64Data = System.Text.Encoding.ASCII.GetBytes (String.Format ("{0}:{1}", credential.Username, credential.Password));
			string basicHeader = String.Format ("Basic {0}", System.Convert.ToBase64String (base64Data));
			
			httpRequest.Headers.Set ("Authorization", basicHeader);
			
			FillStream (httpRequest.GetRequestStream(), boundarybytes, parameters, file, paramName, contentType);		
			
			HttpWebResponse response = (HttpWebResponse)httpRequest.GetResponse (); 
			
			using (Stream responseStream = response.GetResponseStream()) {
				using (StreamReader responseReader = new StreamReader( responseStream )) {					
					return new HttpResult (response, responseReader.ReadToEnd());
				}
			}
			
		}
		
		public static void FillStream (Stream requestStream, byte[] boundaryBytes, IDictionary<string,string> parameters, string file, string fileParameterName, string contentType)
		{
			
			byte[] newLine = System.Text.Encoding.ASCII.GetBytes ("\r\n");
			
			using (requestStream) {
				
				requestStream.Write (boundaryBytes, 0, boundaryBytes.Length);
				requestStream.Write (newLine, 0, newLine.Length);
				
				string formdataTemplate = "Content-Disposition: form-data; name=\"{0}\"\r\n\r\n{1}";
				
				foreach (KeyValuePair<string,string> pair in parameters) {
					string formitem = string.Format (formdataTemplate, pair.Key, pair.Value);
					byte[] formitembytes = System.Text.Encoding.UTF8.GetBytes (formitem);
					requestStream.Write (formitembytes, 0, formitembytes.Length);
					requestStream.Write (newLine, 0, newLine.Length);
					requestStream.Write (boundaryBytes, 0, boundaryBytes.Length);
					requestStream.Write (newLine, 0, newLine.Length);
				}

				string headerTemplate = "Content-Disposition: form-data; name=\"{0}\"; filename=\"{1}\"\r\nContent-Type: {2}\r\n\r\n";
				string header = string.Format (headerTemplate, fileParameterName, Path.GetFileName (file), contentType);
				byte[] headerbytes = System.Text.Encoding.UTF8.GetBytes (header);
				requestStream.Write (headerbytes, 0, headerbytes.Length);
			
				using (FileStream fileStream = new FileStream (file, FileMode.Open, FileAccess.Read)) {
			
					byte[] buffer = new byte[4096];
					int bytesRead = 0;
			
					while ((bytesRead = fileStream.Read(buffer, 0, buffer.Length)) != 0) {
						requestStream.Write (buffer, 0, bytesRead);
					}
			
				}
				
				requestStream.Write (newLine, 0, newLine.Length);
				requestStream.Write (boundaryBytes, 0, boundaryBytes.Length);
				byte[] dashes = System.Text.Encoding.ASCII.GetBytes ("--");
				requestStream.Write (dashes, 0, dashes.Length);
				requestStream.Write (newLine, 0, newLine.Length);
				requestStream.Flush ();
				
			}			
			
		}		
		
	}
}

HttpResult ? Is it missing here? A NuGet package ?