Amazon.S3.Model.GetPreSignedUrlRequest.IsSetExpires C# (CSharp) Method

        public bool IsSetExpires()
        {
            return this.expires.HasValue;
        }

        /// <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>
        /// <returns>A string that is the signed http request.</returns>
        /// <exception cref="T:System.ArgumentException" />
        /// <exception cref="T:System.ArgumentNullException" />
        public string GetPreSignedURL(GetPreSignedUrlRequest request)
        {
            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 = AWSConfigs.S3Config.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")
                aws4Signing = true;

            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 handler = new AmazonS3PostMarshallHandler();
            handler.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
            {
                this.Signer.Sign(irequest, this.Config, 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;
        }