net/http: Responses should have a field for connection information

[gopherbot]

by ask@develooper.com:

Similar to the new TLS field with the tls.ConnectionState in the http.Response struct
it'd be useful to get access to some connection information.

For my use case I was missing the IP the client connected to (RemoteAddr); I am not sure
if there's other information in the current connection API that would be useful to
expose.

[ianlancetaylor]

Comment 1:

Labels changed: added repo-main, release-none.

[josharian]

Comment 2:

Same for Requests, please.
We run http servers with a custom network stack, and we just hit a situation in which
we'd like to be able to inspect the underlying net.Conn from an http.Handler, in order
to get at security information associated with the connection.
I'm happy to implement. Brad, before I start, any concerns or API commentary? The
obvious thing to do is to expose the net.Conn directly in each case and document it as
read-only and not to be stored, but that enables all kinds of foot-shooting.

Status changed to Accepted.

[josharian]

Comment 3:

See also discussion at https://groups.google.com/forum/#!topic/Golang-nuts/cMs8b7iL5KI.

[bradfitz]

Comment 4:

I'd prefer to stop growing Request and Response, both for memory and API bloat reasons.
Is it possible to achieve this via a new optional hook on *http.Transport instead? Some
callback that happens at certain point(s) with the Request or Response and gives you the
net.Conn info and then you can do what you will with the info, perhaps stuffing it in
magic headers on your request or reply even...?)

[josharian]

Comment 5:

We found a workaround.  Can't speak for the OP.

[ysmolski]

Not sure if I should close the issue. It has some important bits, but @josharian found a solution back in time which involved something other than modifying the net/http. There was in interest to this issues in last 4 years. My bet that we can close it down.

[bradfitz]

Closing as duplicate of #5465 and #23707 (which I sketched out recently but haven't yet mailed).