使用ASP.NET Core Web API上传文件至Cloudflare R2遇签名错误求助

我开发了一个ASP.NET Core Web API项目，尝试通过AWSSDK将文件上传至Cloudflare R2，但遇到了签名相关的错误。

现有代码 #

using Amazon.Runtime;
using Amazon.S3;
using Amazon.S3.Model;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Infrastructure;

namespace xxx.API.Controllers
{
    [ApiController]
    [Route("api/[controller]")]
    [AllowAnonymous]
    public class CloudflareR2Controller
    {
        private readonly IAmazonS3 _s3Client;

        public CloudflareR2Controller(IConfiguration configuration)
        {
            string accessKeyId = "aaa";
            string secretAccessKey = "bbb";
            string serviceUrl = "https://ccc.r2.cloudflarestorage.com";
            AWSCredentials credentials = new BasicAWSCredentials(accessKeyId, secretAccessKey);
            AmazonS3Config config = new AmazonS3Config
            {
                ServiceURL = serviceUrl

            };
            _s3Client = new AmazonS3Client(credentials, config);
        }

        [HttpPut("objects/{bucketName}")]
        public async Task<IActionResult> UploadObject(string bucketName, [FromBody] string filePath)
        {
            try
            {
                PutObjectRequest request = new PutObjectRequest
                {
                    FilePath = @filePath,
                    BucketName = bucketName,
                    ServerSideEncryptionMethod = ServerSideEncryptionMethod.AES256
                };

                PutObjectResponse response = await _s3Client.PutObjectAsync(request);

                Console.WriteLine("ETag: {0}", response.ETag);
                //await _cloudflareR2Client.UploadObject(filePath, bucketName);
                return Ok(response);
            }
            catch (Exception ex)
            {
                return StatusCode(500, "Error: " + ex.Message);
            }
        }

        private IActionResult StatusCode(int v1, string v2)
        {
            throw new NotImplementedException();
        }

        [HttpGet]
        public virtual OkObjectResult Ok([ActionResultObjectValue] object? value)
        => new OkObjectResult(value);

        [HttpGet("presigned-url/{bucketName}/{objectKey}")]
        public IActionResult GeneratePresignedUrl(string bucketName, string objectKey)
        {
            try
            {
                //_cloudflareR2Client.GeneratePresignedUrl(bucketName, objectKey);
                return Ok(bucketName);
            }
            catch (Exception ex)
            {
                return StatusCode(500, "Error: " + ex.Message);
            }
        }

    }
}

遇到的第一个错误 #

"STREAMING-AWS4-HMAC-SHA256-PAYLOAD not implemented"

尝试修改后的代码 #

PutObjectRequest request = new PutObjectRequest
{
    FilePath = @filePath,
    BucketName = bucketName,
    DisablePayloadSigning=true, //新增代码
    ServerSideEncryptionMethod = ServerSideEncryptionMethod.AES256
};

修改后出现的新错误 #

{Please use "STREAMING-AWS4-HMAC-SHA256-PAYLOAD"}

解决思路与替代方案 #

1. 调整S3客户端配置，适配R2的签名要求 #

Cloudflare R2仅支持AWS v4签名，且需要指定兼容区域，同时强制路径样式访问。修改AmazonS3Config的配置：

AmazonS3Config config = new AmazonS3Config
{
    ServiceURL = serviceUrl,
    SignatureVersion = "v4",
    RegionEndpoint = RegionEndpoint.USEast1, // R2兼容us-east-1区域
    ForcePathStyle = true // R2要求使用路径样式访问
};

2. 改用文件流上传，避免FilePath的签名问题 #

直接使用FilePath上传时，AWSSDK可能无法正确处理流式签名。改用InputStream传入文件流：

[HttpPut("objects/{bucketName}")]
public async Task<IActionResult> UploadObject(string bucketName, [FromBody] string filePath)
{
    try
    {
        var fileName = Path.GetFileName(filePath);
        using (var fileStream = new FileStream(filePath, FileMode.Open, FileAccess.Read))
        {
            PutObjectRequest request = new PutObjectRequest
            {
                InputStream = fileStream,
                BucketName = bucketName,
                Key = fileName,
                ServerSideEncryptionMethod = ServerSideEncryptionMethod.AES256
            };

            var response = await _s3Client.PutObjectAsync(request);
            Console.WriteLine("ETag: {0}", response.ETag);
            return Ok(response);
        }
    }
    catch (Exception ex)
    {
        return StatusCode(500, "Error: " + ex.Message);
    }
}

3. 修复控制器的基础方法实现 #

当前控制器未继承ControllerBase，导致自定义的StatusCode和Ok方法存在问题。修改控制器定义：

public class CloudflareR2Controller : ControllerBase

这样可以直接使用框架内置的StatusCode、Ok等方法，无需自行实现。

4. 替代方案：使用Cloudflare官方工具 #

如果AWSSDK的兼容问题无法解决，可以直接使用Cloudflare官方提供的API或SDK（如Cloudflare.NET）进行文件上传，完全适配R2的特性。

内容的提问来源于stack exchange，提问作者fbdev1907