Feature: Support Node.JS types

[hacdias]

The old version of the library, node-cbor, has a flag to enable canonical encoding as per section 3.9 from the RFC. I was planning on using cbor2 since it's newer, but it seems to lack this functionality.

Are there any plans on supporting canonical encoding natively?

[hildjj]

"Canonical" has gotten a lot more complicated since the CDE discussions. If you set the "cde" option, you'll probably get what you want. You might also want dCBOR, depending on your use case. There's an option for that too. Both of those set a bunch of smaller preferences all at once, but the smaller prefs are tweakable. I'd recommend trying different settings on the playground to see how they all fit together.

Alternately, if you'd like to tell me more about your application, I'd be happy to give you an opinion on what settings would be good for you.

[hacdias]

Thanks for the reply. Specifically, I need Section 3.9 from RFC7049, in order to generate the data to sign for COSE (RFC 8152). Neither cde, nor dcbor get to the same compact CBOR as the canonical flag from node-cbor

[hildjj]

The only difference I can think of is in map key ordering. node-cbor probably uses lengthFirstDeterministic instead of coreDeterministic. See https://www.rfc-editor.org/rfc/rfc8949#length-first

If you have an example, I can diagnose better.

[hacdias]

So, I did some further debugging to try understanding what's going on. I think the issue is that I assumed cbor2 would behave the same way when it comes to encoding a Buffer.

It seems that cbor2 encodes them as an object (with a type and data fields) instead of as a byte sequence. Replacing the Buffer for an Uint8Array solved my issue, without even needing to turn on cde or dcbor.

Perhaps obvious since this library is made to be used on both node.js and the browser. I see there's an example on README showing how to register an encoder for the Buffer type. Using that solves the issue.

Thanks!

[hildjj]

I should probably write an add-on that does Node types like Buffer. You're right that it can't be easily built-in since cbor2 is supposed to work without shims on the web. Let's keep this open to track that feature request. I'll rename the issue to make it easier for me to see what's needed.

Thanks for doing the work to figure this out!

[hildjj]

Types needed:

• Buffer
• streams?

See #77.

[hildjj]

BTW, in the meantime, the README has the 3 lines of code you need to implement Buffer.

[hildjj]

If we were to add Buffer, I think I'd want it to round-trip back to Buffer, rather than being indistinguishable from Uint8Array, particularly for the Ava snapshot use case.