tree 3d2fc3a56cd618195f5a91b28d046495acf67e9a
parent a8c8b387f1987b4fd8d79f634be9e0a413c75ca1
author David Benjamin <davidben@google.com> 1483365407 -0500
committer Adam Langley <agl@google.com> 1484866991 +0000

Never send SNI warning alerts.

TLS 1.3 forbids warning alerts, and sending these is a bad idea. Per RFC
6066:

   If the server understood the ClientHello extension but
   does not recognize the server name, the server SHOULD take one of two
   actions: either abort the handshake by sending a fatal-level
   unrecognized_name(112) alert or continue the handshake.  It is NOT
   RECOMMENDED to send a warning-level unrecognized_name(112) alert,
   because the client's behavior in response to warning-level alerts is
   unpredictable.

The motivation is to cut down on the number of places where we send
non-closing alerts. We can't remove them yet (SSL 3.0 and TLS 1.3 draft
18 need to go), but eventually this can be a simplifying assumption.
Already this means DTLS never sends warning alerts, which is good
because DTLS can't retransmit them.

Change-Id: I577a1eb9c23e66d28235c0fbe913f00965e19486
Reviewed-on: https://boringssl-review.googlesource.com/13221
Reviewed-by: Adam Langley <agl@google.com>