/// <summary>
/// Create a signed URL allowing access to a resource that would
/// usually require authentication.
/// </summary>
/// <remarks>
/// <para>
/// When using query string authentication you create a query,
/// specify an expiration time for the query, sign it with your
/// signature, place the data in an HTTP request, and distribute
/// the request to a user or embed the request in a web page.
/// </para>
/// <para>
/// A PreSigned URL can be generated for GET, PUT, DELETE and HEAD
/// operations on your bucketName, keys, and versions.
/// </para>
/// </remarks>
/// <param name="request">The GetPreSignedUrlRequest that defines the
/// parameters of the operation.</param>
/// <param name="useSigV2Fallback">determines if signing will fall back to SigV2 if the
/// signing region is us-east-1
/// <returns>A string that is the signed http request.</returns>
/// <exception cref="T:System.ArgumentException" />
/// <exception cref="T:System.ArgumentNullException" />
internal string GetPreSignedURLInternal(GetPreSignedUrlRequest request, bool useSigV2Fallback = true)
{
if (Credentials == null)
{
throw new AmazonS3Exception("Credentials must be specified, cannot call method anonymously");
}
if (request == null)
{
throw new ArgumentNullException("request", "The PreSignedUrlRequest specified is null!");
}
if (!request.IsSetExpires())
{
throw new InvalidOperationException("The Expires specified is null!");
}
var aws4Signing = AWSConfigsS3.UseSignatureVersion4;
var region = AWS4Signer.DetermineSigningRegion(Config, "s3", alternateEndpoint: null, request: null);
if (aws4Signing && string.IsNullOrEmpty(region))
{
throw new InvalidOperationException("To use AWS4 signing, a region must be specified in the client configuration using the AuthenticationRegion or Region properties, or be determinable from the service URL.");
}
RegionEndpoint endpoint = RegionEndpoint.GetBySystemName(region);
if (endpoint.GetEndpointForService("s3").SignatureVersionOverride == "4" || endpoint.GetEndpointForService("s3").SignatureVersionOverride == null)
{
aws4Signing = true;
}
var fallbackToSigV2 = useSigV2Fallback && !AWSConfigsS3.UseSigV4SetExplicitly;
if (endpoint == RegionEndpoint.USEast1 && fallbackToSigV2)
{
aws4Signing = false;
}
// If the expiration is longer than SigV4 will allow then automatically use SigV2 instead.
// But only if the region we're signing for allows SigV2.
if (aws4Signing)
{
var secondsUntilExpiration = GetSecondsUntilExpiration(request, aws4Signing);
if (secondsUntilExpiration > AWS4PreSignedUrlSigner.MaxAWS4PreSignedUrlExpiry &&
endpoint.GetEndpointForService("s3").SignatureVersionOverride == "2")
{
aws4Signing = false;
}
}
var immutableCredentials = Credentials.GetCredentials();
var irequest = Marshall(request, immutableCredentials.AccessKey, immutableCredentials.Token, aws4Signing);
irequest.Endpoint = EndpointResolver.DetermineEndpoint(this.Config, irequest);
var context = new Amazon.Runtime.Internal.ExecutionContext(new Amazon.Runtime.Internal.RequestContext(true)
{
Request = irequest, ClientConfig = this.Config
}, null);
AmazonS3PostMarshallHandler.ProcessRequestHandlers(context);
var metrics = new RequestMetrics();
string authorization;
if (aws4Signing)
{
var aws4Signer = new AWS4PreSignedUrlSigner();
var signingResult = aws4Signer.SignRequest(irequest,
this.Config,
metrics,
immutableCredentials.AccessKey,
immutableCredentials.SecretKey);
authorization = "&" + signingResult.ForQueryParameters;
}
else
{
S3Signer.SignRequest(irequest, metrics, immutableCredentials.AccessKey, immutableCredentials.SecretKey);
authorization = irequest.Headers[HeaderKeys.AuthorizationHeader];
authorization = authorization.Substring(authorization.IndexOf(":", StringComparison.Ordinal) + 1);
authorization = "&Signature=" + AmazonS3Util.UrlEncode(authorization, false);
}
Uri url = AmazonServiceClient.ComposeUrl(irequest);
string result = url.AbsoluteUri + authorization;
Protocol protocol = DetermineProtocol();
if (request.Protocol != protocol)
{
switch (protocol)
{
case Protocol.HTTP:
result = result.Replace("http://", "https://");
break;
case Protocol.HTTPS:
result = result.Replace("https://", "http://");
break;
}
}
return(result);
}
