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copied!<h2>Update [workaround]</h2> <p>I've meanwhile resolved the contradicting test results of mine, which stem from respectively unsystematic testing and URL manipulations. The following <strong>workaround</strong> does the trick for me (i.e. tested and reproducible), simply starting from your solution:</p> <pre><code>string bucketName = "foo.example.com"; // [...] GetPreSignedUrlRequest request = new GetPreSignedUrlRequest() .WithBucketName(bucketName) .WithKey(key) .WithExpires(DateTime.Now.AddMinutes(32)) .WithProtocol(Protocol.HTTP); </code></pre> <p>Now this yields the erroneous URL with a duplicate domain name, i.e. <code>http://foo.example.com.foo.example.com/myfile.txt?[...]</code></p> <p>The duplicate can simply be removed though, e.g.:</p> <pre><code>string url = s3Client.GetPreSignedURL(request); // KLUDGE: remove duplicate domain name. url = url.Replace(bucketName + "." + bucketName, bucketName); </code></pre> <p>This yields a proper working pre-signed URL for me (i.e. <code>http://foo.example.com/myfile.txt?[...]</code>) by working around the encountered limitation regarding the desired approach outlined below.</p> <h3>Justification</h3> <p>Manipulating the generated URL like so seems odd, but this not having an effect on the query string authentication is in line with how these signatures are created, see <a href="http://docs.amazonwebservices.com/AmazonS3/latest/dev/RESTAuthentication.html#RESTAuthenticationQueryStringAuth" rel="nofollow noreferrer">Query String Request Authentication Alternative</a>, where you'll find the <em>pseudo-grammar that illustrates the query string request authentication method</em>:</p> <pre><code>StringToSign = HTTP-VERB + "\n" + Content-MD5 + "\n" + Content-Type + "\n" + Expires + "\n" + CanonicalizedAmzHeaders + CanonicalizedResource; </code></pre> <p>That is, the domain name isn't used for the signature creation at all, rather only information regarding the resource itself; section <em>Example Query String Request Authentication</em> right below the referenced pseudo-grammar fragment illustrates this with an actual resource.</p> <h3>Assessment</h3> <p>I don't know whether there is still a misunderstanding on our part or whether this might just be a bug in the <a href="http://aws.amazon.com/sdkfornet/" rel="nofollow noreferrer">AWS SDK for .NET</a>, see e.g. <a href="https://stackoverflow.com/questions/9051650/why-is-my-s3-pre-signed-request-invalid-when-i-set-a-response-header-override-th">Why is my S3 pre-signed request invalid when I set a response header override that contains a “+”?</a> for a related bug resolved via a similar workaround as well, which has meanwhile been fixed though; accordingly, this should likely be escalated to the AWS forums and/or support channels to get an appropriate answer or solution.</p> <p>Good luck!</p> <hr> <h2>Desired answer [dysfunctional]</h2> <p>The S3 CNAME handling implies the bucket name already, so all you need to do is removing your bucket name from <code>GetPreSignedUrlRequest</code>, i.e. it should look like so:</p> <pre><code>GetPreSignedUrlRequest request = new GetPreSignedUrlRequest() .WithKey(key) .WithExpires(DateTime.Now.AddMinutes(5)) .WithProtocol(Protocol.HTTP); </code></pre> <p><strike>I've tested this with a bucket of mine and it works as expected like so.</strike></p>

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