Uploading through REST API to blob storage throws (403) Forbidden Error.

Question

Can someone help. Am facing same problem.. but using simple code to do things. Can someone help please.

Note - Am able to upload the same data using StorageClient dll.

But with Http, am facing issues. On desktop it says (403) Forbidden Error. I have used Fiddler to fig what my StorageClient is sending & replicated that in HttpWebRequest.

Thanks.

public bool StartGPSDataUpload(Guid raceId)
        {
            bool bResult = false;
            try
            {
                string URL = "";
                URL = "http://xxxx.blob.core.windows.net/videos/"+ Uri.EscapeDataString("6a3c2acd-8a2f-41ee-9203-137d7ba7ecd5-GPS-test.txt") +"?timeout=90";
                WebReq = (HttpWebRequest)HttpWebRequest.Create(URL);
                WebReq.Method = "PUT";
                WebReq.KeepAlive = false;
                WebReq.Headers["x-ms-version"] = "2011-08-18";
                WebReq.UserAgent = "myapp";
                WebReq.Headers["x-ms-blob-type"] = "BlockBlob";
                WebReq.Headers["x-ms-date"] = DateTime.UtcNow.ToString("R");
                WebReq.Headers["Authorization"] = "SharedKey xxxx:ioOqYh7CnftgX8c1DxX5OiRWL1v9TfIJMmTl8m4ogrY=";
                gpsdataInByte = ReadGPSFile(raceId);
                WebReq.ContentLength = gpsdataInByte.Length;
                
                using (HttpWebResponse response = (HttpWebResponse)WebReq.GetResponse())
                {
                    String ETag = response.Headers["ETag"];
                    System.Windows.Forms.MessageBox.Show(ETag);
                }
                
            }
            catch (Exception ex)
            {
                System.Windows.Forms.MessageBox.Show("error - " + ex.ToString());
            }

            return bResult;
        }

Answer 1

How are you deriving the auth signature? I don't see any code that computes the canonicalized resource, headers, etc., and signs them. I think perhaps you're assuming a simpler auth scheme than is actually used by WA storage.

Answer 2

Hello Steve,

You are right. I was assuming it to be simpler. I was able to get things working. Thanks for the tip.

For others who may benefit from my stumbles, here is the sample code.

This article was helful http://convective.wordpress.com/2010/08/18/examples-of-the-windows-azure-storage-services-rest-api/

Here is the sample code for others. Usage will be (new AzureStorageHelper()).PutBlob("yourcontainername", "yourblobfilename");

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

namespace TestBlobUpload
{
    class AzureStorageConstants
    {
        public static string Key="xxxx";
        public static string SharedKeyAuthorizationScheme = "SharedKey";
        public static string Account="xxxx";
        public static string BlobEndPoint="http://xxxxx.blob.core.windows.net/";
        
    }
    class AzureStorageHelper
    {
        public String CreateAuthorizationHeader(String canonicalizedString)
         {
             String signature = string.Empty;
             //UTF8Encoding utf8Encoding = new UTF8Encoding();
             //byte[] storageKey = utf8Encoding.GetBytes(AzureStorageConstants.Key);
             byte[] storageKey = Convert.FromBase64String(AzureStorageConstants.Key);

             using (HMACSHA256 hmacSha256 = new HMACSHA256(storageKey))
             {
                 Byte[] dataToHmac = System.Text.Encoding.UTF8.GetBytes(canonicalizedString);
                 signature = Convert.ToBase64String(hmacSha256.ComputeHash(dataToHmac));
             }
 
            String authorizationHeader = String.Format(
                   CultureInfo.InvariantCulture,
                   "{0} {1}:{2}",
                   AzureStorageConstants.SharedKeyAuthorizationScheme,
                   AzureStorageConstants.Account,
                   signature);
 
            return authorizationHeader;
         }

        public void PutBlob(String containerName, String blobName)
         {
             String requestMethod = "PUT";
 
            String urlPath = String.Format("{0}/{1}", containerName, blobName);

            String storageServiceVersion = "2011-08-18"; // "2009-09-19";
 
            String dateInRfc1123Format = DateTime.UtcNow.ToString("R", CultureInfo.InvariantCulture);
 
            String content = "The Name of This Band is Talking Heads";
             UTF8Encoding utf8Encoding = new UTF8Encoding();
             Byte[] blobContent = utf8Encoding.GetBytes(content);
             Int32 blobLength = blobContent.Length;
 
            const String blobType = "BlockBlob";
 
            
            String canonicalizedHeaders = String.Format(
                   "x-ms-blob-type:{0}\nx-ms-date:{1}\nx-ms-version:{2}",
                   blobType,
                   dateInRfc1123Format,
                   storageServiceVersion);
            /*
            String canonicalizedHeaders = String.Format(
             "x-mx-blob-content-length:{3}\nx-ms-blob-type:{0}\nx-ms-date:{1}\nx-ms-version:{2}",
             blobType,
             dateInRfc1123Format,
             storageServiceVersion,
             blobLength.ToString());
            */
             String canonicalizedResource = String.Format("/{0}/{1}", AzureStorageConstants.Account, urlPath);
             String stringToSign = String.Format(
                   "{0}\n\n\n{1}\n\n\n\n\n\n\n\n\n{2}\n{3}",
                   requestMethod,
                   blobLength,
                   canonicalizedHeaders,
                   canonicalizedResource);
             String authorizationHeader = CreateAuthorizationHeader(stringToSign);
 
            Uri uri = new Uri(AzureStorageConstants.BlobEndPoint + urlPath);
             HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
             request.Method = requestMethod;
             request.Headers.Add("x-ms-blob-type", blobType);
             request.Headers.Add("x-ms-date", dateInRfc1123Format);
             request.Headers.Add("x-ms-version", storageServiceVersion);
             request.Headers.Add("Authorization", authorizationHeader);
             request.ContentLength = blobLength;

             try
             {
                 using (Stream requestStream = request.GetRequestStream())
                 {
                     requestStream.Write(blobContent, 0, blobLength);
                 }

                 using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
                 {
                     String ETag = response.Headers["ETag"];
                 }
                 System.Windows.Forms.MessageBox.Show("Success");
             }
             catch (WebException webEx)
             {
                 if (webEx != null)
                 {
                     WebResponse resp = webEx.Response;
                     if (resp != null)
                     {
                         using (StreamReader sr = new StreamReader(resp.GetResponseStream(), true))
                         {
                             string responseText = sr.ReadToEnd();//This is where details about this 403 message can be found
                             System.Windows.Forms.MessageBox.Show("error - " + responseText);
                         }
                     }
                 }
             }
         }

    }
}