Throw specific error if Content-Length can't be computed

[trivikr]

Is your feature request related to a problem? Please describe.

S3 throws NotImplemented Error in Content-Length can't be computed in https://github.com/aws/aws-sdk-js-v3/issues/3377 The error can be more specific, i.e. Content-Length can't be computed.

Describe the solution you'd like

Throw error in calculateBodyLength if length can't be computed.

• https://github.com/aws/aws-sdk-js-v3/blob/main/packages%2Futil-body-length-node%2Fsrc%2FcalculateBodyLength.ts
• https://github.com/aws/aws-sdk-js-v3/blob/main/packages%2Futil-body-length-browser%2Fsrc%2FcalculateBodyLength.ts

Describe alternatives you've considered

N/A

Additional context

This suggestion was discussed and approved internally.

[trivikr]

As of now, the contentLengthMiddleware skips setting Content-Length header if it is undefined. https://github.com/aws/aws-sdk-js-v3/blob/88f8cc2d3d33f4dc6d06312e75f70725c89d1f17/packages/middleware-content-length/src/index.ts#L27-L33

[trivikr]

From rfc7230 specification 3.3.2

A user agent SHOULD send a Content-Length in a request message when no Transfer-Encoding is sent and the request method defines a meaning for an enclosed payload body. For example, a Content-Length header field is normally sent in a POST request even when the value is 0 (indicating an empty payload body). A user agent SHOULD NOT send a Content-Length header field when the request message does not contain a payload body and the method semantics do not anticipate such a body.

[trivikr]

The contentLengthMiddleware checks if body is defined and Content-Length header is not set before calling bodyLengthChecker. And as per spec it should be fine to throw error if bodyLengthChecker, as user agent should send a Content-Length in case of enclosed payload body.

I've asked this question on internal Slack channel to check behaviors in other SDKs, and will revisit this feature request in future.

[trivikr]

The AWS SDK for Python and CLI sets Transfer-Encoding to chunked if they're not able to determine content-length https://github.com/boto/botocore/blob/354e9cb22017112a6f72fb20c36b133c9f346002/botocore/awsrequest.py#L364-L374