1288044 - Disable NPN support

Status: RESOLVED FIXED

(NSS :: Libraries, defect, P3)

Description

[Franziskus Kiefer [:franziskus]]

NPN and ALPN usage is currently broken when external callbacks are used (see bug 1284412). Fixing this might either break NPN or API stability (it might work though, see patch at [1]).
There's already work being done to remove NPN support in Firefox (bug 1248198). Chrome stopped supporting NPN a couple of months ago.

From discussion on nss-dev we concluded the following

1. We believe NPN is only used in SPDY and HTTP/2, and a system that supports NPN but not ALPN probably only supports SPDY.
2. If NPN is turned off, such systems will still function because they will just use HTTP/1.1.
3. NPN is difficult to support without breaking something
4. NPN is not an IETF RFC
5. NSS never implemented server support for NPN.
6. NPN support is already broken for external callbacks.
7. According to the chrome team there was no significant drop in h2 rates after disabling npn.

[1] https://codereview.appspot.com/303000043

Comment 1

[Martin Thomson [:mt:]]

Attachment: bug1288044-1.patch

Comment 2

[Franziskus Kiefer [:franziskus]]

prevent NPN from being enabled
https://hg.mozilla.org/projects/nss/rev/24581a36b2bb

Comment 3

[Tim Taubert [:ttaubert] (inactive)]

This landed about a year ago, still too early to drop it?

Comment 4

[Kai Engert [:KaiE:]]

Thanks for the reminder. I'm optimistic, but have asked a few people for feedback. Please let's wait another week to see if anyone presents good arguments for waiting longer.

Comment 5

[Kai Engert [:KaiE:]]

We couldn't find any argument to keep the code.

Thanks for asking, and please feel free to go ahead with the removal.

Comment 6

[Martin Thomson [:mt:]]

I'm going to close this as resolved (3.28, yay) and make a new bug for the code removal.  Thanks for checking Kai.