S3Helper

S3Helper.cs

using System;
using System.Net;
using System.Net.Http;
using System.Collections.Generic;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using ToolBelt;
using System.IO;

//
// Code that did the pre-v4 Authorization for AWS.  Superceded by the vastly more complicated AWS-v4 algorithm.
//

namespace Artifact.Utility
{
    public static class S3Region
    {
        public static readonly string USStandard = "s3-external-1.amazonaws.com";
        public static readonly string USWestOregon = "s3-us-west-2.amazonaws.com";
        public static readonly string USWestCalifornia = "s3-us-west-1.amazonaws.com";
    }

    public class S3Helper
    {
        public S3Helper(string s3AccessKeyId, string s3SecretAccessKey, string s3Region)
        {
            S3SecretAccessKey = s3SecretAccessKey;
            S3AccessKeyId = s3AccessKeyId;
            S3Region = s3Region;
        }

        public string S3AccessKeyId { get; set; }

        public string S3SecretAccessKey { get; set; }

        public string S3Region { get; set; }

        public HttpWebRequest CreateS3Request(
            HttpMethod method, 
            string bucketName = null, 
            string objectName = null, 
            IEnumerable<KeyValuePair<string, string>> amzHeaders = null)
        {
            // See http://docs.aws.amazon.com/AmazonS3/latest/dev/RESTAuthentication.html for the gory details of this call

            string host = "s3.amazonaws.com";
            string url = "http://";
            string resource = "/";

            if (bucketName != null)
            {
                host = bucketName + "." + host;
                
                if (objectName != null)
                {
                    if (objectName.StartsWith("/"))
                        objectName = objectName.Substring(1);
                    
                    resource += objectName;
                }
            }

            url += host + resource;

            HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest;
            WebHeaderCollection headers = (request as HttpWebRequest).Headers;

            request.Method = method.ToString();
            request.Host = host;
            request.Date = DateTime.UtcNow;

            string contentMD5 = "";
            string contentType = "";
            string amzHeaderString;

            if (amzHeaders != null && amzHeaders.Count() > 0)
            {
                foreach (var amzHeader in amzHeaders)
                {
                    headers.Add(amzHeader.Key, amzHeader.Value);
                }

                amzHeaderString = StringUtility.Join("\n", amzHeaders.Distinct().OrderBy(h => h.Key)
                    .Select(h => String.Format("{0}:{1}", h.Key.ToLower(), h.Value.Replace("\n", " "))).ToList()) + "\n";
            }
            else
                amzHeaderString = "";

            string canonicalString = String.Format(
                                         "{0}\n{1}\n{2}\n{3}\n{4}{5}", 
                                         method.ToString(),
                                         contentMD5, 
                                         contentType,
                                         headers["Date"], 
                                         amzHeaderString,
                                         resource);
            HMACSHA1 hmac = new HMACSHA1(Encoding.UTF8.GetBytes(S3SecretAccessKey));

            headers.Add("Authorization", "AWS " + S3AccessKeyId + ":" + Convert.ToBase64String(hmac.ComputeHash(Encoding.UTF8.GetBytes(canonicalString))));

            return request;
        }

        public static string GetResponseString(WebResponse response)
        {
            using (Stream responseStream = response.GetResponseStream())
            {
                using (StreamReader sr = new StreamReader(responseStream))
                {
                    return sr.ReadToEnd();
                }
            }
        }
    }
}