doc: DEP0066 is slightly incorrect

[simov]

📗 API Reference Docs Problem

• Version: v15.11.0

• Platform: Linux nuc 5.4.0-65-generic The README is oriented towards Node #73~18.04.1-Ubuntu SMP Tue Jan 19 09:02:24 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

• Subsystem: http.ClientRequest

Location

Affected URL(s):

• https://nodejs.org/api/deprecations.html#deprecations_dep0066_outgoingmessage_prototype_headers_outgoingmessage_prototype_headernames

Description

DEP0066 implies that using OutgoingMessage.prototype.getHeaderNames() is equivalent to the now deprecated OutgoingMessage.prototype._headerNames property which is not the case.

OutgoingMessage.prototype._headerNames contains a mapping from lowercase to the exact header names that were sent with the request:

{authorization: "Authorization", host: "Host"}

Where OutgoingMessage.prototype.getHeaderNames() returns only lowercase names.

The now deprecated _headerNames property is useful in http debug logging modules that print the exact header names being sent, as some servers are still picky about those. Not having access to the actual header names will make debugging harder, assuming node still sends the headers as they are sent through the http.request method.

Besides the documentation being misleading about this I'd like to know if there is a way to access the headers being sent going forward, since _headerNames is now deprecated.

[benjamingr]

@nodejs/http

[ronag]

What about rawHeaders?

[simov]

What about rawHeaders?

The issue is with http.ClientRequest, rawHeaders seems to be present only on http.IncomingMessage.

[mcollina]

I think when we deprecated _headerNames we forgot to add a response.getRawHeaderNames(), e.g. the name that will be sent on the wire. I think this will be simple to add, so I flagged it as "good first issue", if you'd like to give it a shot.