new feature: content-length header for presigned write

[xangelix]

Feature Description

S3's API supports signing the content-length and content-length-range headers https://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-HTTPPOSTConstructPolicy.html

Problem and Solution

This prevents an end-user from uploading some theoretical infinite amount of bytes using a presigned write.

Additional Context

I'm not sure what other services might support this.

Are you willing to contribute to the development of this feature?

• [X] Yes, I am willing to contribute to the development of this feature.

[Xuanwo]

Hi, @xangelix. Presign write is not implemented via POST, so I'm afraid we can't add such a restriction.