HttpClient C# PutAsync onto S3 bucket not matching signature provided - amazon-web-services

Question

I'm trying to put an image on a s3 bucket via an upload URL. Here's what I've done so far:
//Get Upload URL & Access the file details
string path = HttpUtility.UrlPathEncode("image/getUploadURL/" + imageFileDetails.Extension + "/" + imageFileDetails.Name + "/" + sessionID);
string uploadURL = " ";
string mimeType = MimeTypesMap.GetMimeType(imageFileDetails.FullName);
HttpResponseMessage response = await client.GetAsync(path);
if (response.IsSuccessStatusCode)
{
var getResponse = await response.Content.ReadAsStringAsync();
dynamic JSONObject = JObject.Parse(getResponse);
uploadURL = JSONObject.data.uploadURL;
if (uploadURL != "" && uploadURL != null)
{
using (var content = new MultipartFormDataContent())
{
Console.WriteLine("UploadURL: {0}", uploadURL);
Console.WriteLine("newFilePath: {0}", newFilePath);
FileStream fileStream = new FileStream(newFilePath, FileMode.Open);
content.Add(new StreamContent(fileStream), "data");
using (
var message = await client.PutAsync(uploadURL, content))
{
var putResponse = await message.Content.ReadAsStringAsync();
Console.WriteLine("PutResponse: {0} " , putResponse);
}
}
Console.ReadKey();
}
I continue to get the following error:
The request signature we calculated does not match the signature you provided. Check your key and signing method.
Should I be approaching this differently? I've tried with RestSharp as well and have not gotten any positive results yet. Any ideas, or workarounds would be appreciated!

Answer 1

Use the Amazon S3 Strongly typed C# client. To upload an object using a presigned URL, you can use this code.
namespace UploadUsingPresignedURLExample
{
using System;
using System.IO;
using System.Net;
using System.Threading.Tasks;
using Amazon.S3;
using Amazon.S3.Model;
/// <summary>
/// This example shows how to upload an object to an Amazon Simple Storage
/// Service (Amazon S3) bucket using a presigned URL. The code first
/// creates a presigned URL and then uses it to upload an object to an
/// Amazon S3 bucket using that URL. The example was created using the
/// AWS SDK for .NET version 3.7 and .NET Core 5.0.
/// </summary>
public class UploadUsingPresignedURL
{
public static void Main()
{
string bucketName = "doc-example-bucket";
string keyName = "samplefile.txt";
string filePath = $"source\\{keyName}";
// Specify how long the signed URL will be valid in hours.
double timeoutDuration = 12;
// If the AWS Region defined for your default user is different
// from the Region where your Amazon S3 bucket is located,
// pass the Region name to the S3 client object's constructor.
// For example: RegionEndpoint.USWest2.
IAmazonS3 client = new AmazonS3Client();
var url = GeneratePreSignedURL(client, bucketName, keyName, timeoutDuration);
var success = UploadObject(filePath, url);
if (success)
{
Console.WriteLine("Upload succeeded.");
}
else
{
Console.WriteLine("Upload failed.");
}
}
/// <summary>
/// Uploads an object to an S3 bucket using the presigned URL passed in
/// the url parameter.
/// </summary>
/// <param name="filePath">The path (including file name) to the local
/// file you want to upload.</param>
/// <param name="url">The presigned URL that will be used to upload the
/// file to the S3 bucket.</param>
/// <returns>A Boolean value indicating the success or failure of the
/// operation, based on the HttpWebResponse.</returns>
public static bool UploadObject(string filePath, string url)
{
HttpWebRequest httpRequest = WebRequest.Create(url) as HttpWebRequest;
httpRequest.Method = "PUT";
using (Stream dataStream = httpRequest.GetRequestStream())
{
var buffer = new byte[8000];
using (FileStream fileStream = new FileStream(filePath, FileMode.Open, FileAccess.Read))
{
int bytesRead = 0;
while ((bytesRead = fileStream.Read(buffer, 0, buffer.Length)) > 0)
{
dataStream.Write(buffer, 0, bytesRead);
}
}
}
HttpWebResponse response = httpRequest.GetResponse() as HttpWebResponse;
return response.StatusCode == HttpStatusCode.OK;
}
/// <summary>
/// Generates a presigned URL which will be used to upload an object to
/// an S3 bucket.
/// </summary>
/// <param name="client">The initialized S3 client object used to call
/// GetPreSignedURL.</param>
/// <param name="bucketName">The name of the S3 bucket to which the
/// presigned URL will point.</param>
/// <param name="objectKey">The name of the file that will be uploaded.</param>
/// <param name="duration">How long (in hours) the presigned URL will
/// be valid.</param>
/// <returns>The generated URL.</returns>
public static string GeneratePreSignedURL(
IAmazonS3 client,
string bucketName,
string objectKey,
double duration)
{
var request = new GetPreSignedUrlRequest
{
BucketName = bucketName,
Key = objectKey,
Verb = HttpVerb.PUT,
Expires = DateTime.UtcNow.AddHours(duration),
};
string url = client.GetPreSignedURL(request);
return url;
}
}
}
You can find this example and other Amazon S3 examples in Github here:
https://github.com/awsdocs/aws-doc-sdk-examples/tree/master/dotnetv3/S3

Answer 2

After some extensive research, I was able to located the error in my code. When doing the GET call I was passing the incorrect file type, then, when trying to do the PUT call with the MIME type, it 403'd.
I had to update my initial GET path with the matching file type, and the appropriate encoding.
On my example below, it's hard coded, that'll be changing of course, but that was the error:
string path = HttpUtility.UrlPathEncode("image/getUploadURL/image%2Fpng/" + imageFileDetails.Name + "/" + sessionID);