Download from Azure Storage adding single quotes around filename - safari

Question

I'm working on a site hosted in Azure that has a download functionality. To reduce the load on our servers, the download is done use Shared Access Signatures. However, in Safari when downloading the file, the filename is wrapped in single quotes, as in myFile.txt downloads as 'myFile.txt'. This has made it so zips being downloaded have to be renamed by the client so the contents can be extracted.
Code for generated the Shared Access Signature is as follows:
CloudBlockBlob blob = container.GetBlockBlobReference(Helpers.StringHelper.TrimIfNotNull(blobName));
if (!blob.Exists())
{
return string.Empty;
}
var sasConstraints = new SharedAccessBlobPolicy();
sasConstraints.SharedAccessStartTime = DateTime.UtcNow.AddSeconds(-5);
sasConstraints.SharedAccessExpiryTime = DateTime.UtcNow.Add(duration);
sasConstraints.Permissions = SharedAccessBlobPermissions.Read | SharedAccessBlobPermissions.Write;
var headers = new SharedAccessBlobHeaders();
string filename = blobName;
if (filename.Contains("/"))
{
filename = blobName.Substring(blobName.LastIndexOf("/") + 1, blobName.Length - blobName.LastIndexOf("/") - 1);
}
headers.ContentDisposition = "attachment; filename='" + filename + "'";
//Generate the shared access signature on the blob, setting the constraints directly on the signature.
string sasBlobToken = blob.GetSharedAccessSignature(sasConstraints, headers);
//Return the URI string for the container, including the SAS token.
return blob.Uri + sasBlobToken;
This code has worked fine in Chrome, Firefox, and IE. Is there something I'm missing with the headers? The only one I'm modifying is content-disposition.

Answer 1

You should use double quotes for quoted strings in HTTP headers, as outlined in RFC2616.
So replace
headers.ContentDisposition = "attachment; filename='" + filename + "'";
with
headers.ContentDisposition = "attachment; filename=\"" + filename + "\"";