Create Shared Access Token with Microsoft.WindowsAzure.Storage returns 403 - azure

Question

I have a fairly simple method that uses the NEW Storage API to create a SAS and copy a blob from one container to another.
I am trying to use this to Copy blob BETWEEN STORAGE ACCOUNTS. So I have TWo Storage accounts, with the exact same Containers, and I am trying to copy a blob from the Storage Account's Container to another Storage Account's Container.
I don't know if the SDK is built for that, but it seems like it would be a common scenario.
Some additional information:
I create the token on the Destination Container.
Does that token need to be created on both the source and destination? Does it take time to register the token? Do I need to create it for each request, or only once per token "lifetime"?
I should mention a 403 is an Unauthorized Result http error code.
private static string CreateSharedAccessToken(CloudBlobClient blobClient, string containerName)
{
var container = blobClient.GetContainerReference(containerName);
var blobPermissions = new BlobContainerPermissions();
// The shared access policy provides read/write access to the container for 10 hours:
blobPermissions.SharedAccessPolicies.Add("SolutionPolicy", new SharedAccessBlobPolicy()
{
// To ensure SAS is valid immediately we don’t set start time
// so we can avoid failures caused by small clock differences:
SharedAccessExpiryTime = DateTime.UtcNow.AddHours(1),
Permissions = SharedAccessBlobPermissions.Write |
SharedAccessBlobPermissions.Read
});
blobPermissions.PublicAccess = BlobContainerPublicAccessType.Blob;
container.SetPermissions(blobPermissions);
return container.GetSharedAccessSignature(new SharedAccessBlobPolicy(), "SolutionPolicy");
}
Down the line I use this token to call a copy operation, which returns a 403:
var uri = new Uri(srcBlob.Uri.AbsoluteUri + blobToken);
destBlob.StartCopyFromBlob(uri);
My version of Azure.Storage is 2.1.0.2.
Here is the full copy method in case that helps:
private static void CopyBlobs(
CloudBlobContainer srcContainer, string blobToken,
CloudBlobContainer destContainer)
{
var srcBlobList
= srcContainer.ListBlobs(string.Empty, true, BlobListingDetails.All); // set to none in prod (4perf)
//// get the SAS token to use for all blobs
//string token = srcContainer.GetSharedAccessSignature(
// new SharedAccessBlobPolicy(), "SolutionPolicy");
bool pendingCopy = true;
foreach (var src in srcBlobList)
{
var srcBlob = src as ICloudBlob;
// Determine BlobType:
ICloudBlob destBlob;
if (srcBlob.Properties.BlobType == BlobType.BlockBlob)
{
destBlob = destContainer.GetBlockBlobReference(srcBlob.Name);
}
else
{
destBlob = destContainer.GetPageBlobReference(srcBlob.Name);
}
// Determine Copy State:
if (destBlob.CopyState != null)
{
switch (destBlob.CopyState.Status)
{
case CopyStatus.Failed:
log.Info(destBlob.CopyState);
break;
case CopyStatus.Aborted:
log.Info(destBlob.CopyState);
pendingCopy = true;
destBlob.StartCopyFromBlob(destBlob.CopyState.Source);
return;
case CopyStatus.Pending:
log.Info(destBlob.CopyState);
pendingCopy = true;
break;
}
}
// copy using only Policy ID:
var uri = new Uri(srcBlob.Uri.AbsoluteUri + blobToken);
destBlob.StartCopyFromBlob(uri);
//// copy using src blob as SAS
//var source = new Uri(srcBlob.Uri.AbsoluteUri + token);
//destBlob.StartCopyFromBlob(source);
}
}
And finally the account and client (vetted) code:
var credentials = new StorageCredentials("BAR", "FOO");
var account = new CloudStorageAccount(credentials, true);
var blobClient = account.CreateCloudBlobClient();
var sasToken = CreateSharedAccessToken(blobClient, "content");
When I use a REST client this seems to work... any ideas?

Answer 1

Consider also this problem:
var uri = new Uri(srcBlob.Uri.AbsoluteUri + blobToken);
Probably you are calling the "ToString" method of Uri that produce a "Human redable" version of the url. If the blobToken contain special caracters like for example "+" this will cause a token malformed error on the storage server that will refuse to give you the access.
Use this instead:
String uri = srcBlob.Uri.AbsoluteUri + blobToken;

Answer 2

Shared Access Tokens are not required for this task. I ended up with two accounts and it works fine:
var accountSrc = new CloudStorageAccount(credsSrc, true);
var accountDest = new CloudStorageAccount(credsSrc, true);
var blobClientSrc = accountSrc.CreateCloudBlobClient();
var blobClientDest = accountDest.CreateCloudBlobClient();
// Set permissions on the container.
var permissions = new BlobContainerPermissions {PublicAccess = BlobContainerPublicAccessType.Blob};
srcContainer.SetPermissions(permissions);
destContainer.SetPermissions(permissions);
//grab the blob
var sourceBlob = srcContainer.GetBlockBlobReference("FOO");
var destinationBlob = destContainer.GetBlockBlobReference("BAR");
//create a new blob
destinationBlob.StartCopyFromBlob(sourceBlob);

Answer 3

Since both CloudStorageAccount objects point to the same account, copying without a SAS token would work just fine as you also mentioned.
On the other hand, you need either a publicly accessible blob or a SAS token to copy from another account. So what you tried was correct, but you established a container-level access policy, which can take up to 30 seconds to take effect as also documented in MSDN. During this interval, a SAS token that is associated with the stored access policy will fail with status code 403 (Forbidden), until the access policy becomes active.
One more thing that I would like to point is; when you call Get*BlobReference to create a new blob object, the CopyState property will not be populated until you do a GET/HEAD operation such as FetchAttributes.