crypto/tls: add support for TLS 1.3

[mikioh]

See https://tools.ietf.org/html/draft-ietf-tls-tls13.

Coexistence of IPv4 and IPv6 harms the net package.
Coexistence of HTTP/1.x and HTTP/2 will harm the net/http package.
For now looks coexistence of TLS 1.2 and 1.3 won't harm the crypto/tls package.
How about a variety of compositions on HTTP over TLS over IP?

[bradfitz]

Coexistence of IPv4 and IPv6 harms the net package.

Huh?

Coexistence of HTTP/1.x and HTTP/2 will harm the net/http package.

Huh?

This whole bug report seems to start on unfounded premises, or at least isn't clear.

[rsc]

The draft is still being updated. We can talk about having TLS 1.3 once it's actually an RFC.

[I have no idea what the text in the issue report body is supposed to mean, but the issue title is at least clear.]

[joshuarubin]

maybe it's time to consider this again?

[minux]

TLS 1.3 is still not approved, so I think we should delay this a bit further.

[FiloSottile]

https://go-review.googlesource.com/#/c/33115/ opened a branch for TLS 1.3 development.

[gopherbot]

CL https://golang.org/cl/33164 mentions this issue.

[gopherbot]

CL https://golang.org/cl/33416 mentions this issue.

[gopherbot]

CL https://golang.org/cl/33419 mentions this issue.

[mholt]

I see this is still "Unplanned" -- any possibility of getting this on track for Go 1.9? (Or is the final draft still too far out. I can never figure out where to find the status of these things.)

[bradfitz]

@FiloSottile is working on this. Status?

[FiloSottile]

The server codebase we are using is pretty battle tested and complete now, so the commits starting crypto/tls in https://github.com/cloudflare/tls-tris will make their way into CLs after cleanup. Some already did.

If @agl has the review bandwidth, I can probably power through the client implementation in March. (Or maybe we can consider shipping server first?)

BTW, @bradfitz it would be useful if I could submit for review on Gerrit commits I don't Author. There are a couple in there made by other people that agreed to have them submitted and signed the CLA.

(Feel free to assign me this issue.)