crypto/x509: treat certificate names with trailing dots as invalid

Trailing dots are not allowed in certificate fields like CN and SANs
(while they are allowed and ignored as inputs to verification APIs).
Move to considering names with trailing dots in certificates as invalid
hostnames.

Following the rule of CL 231378, these invalid names lose wildcard
processing, but can still match if there is a 1:1 match, trailing dot
included, with the VerifyHostname input.

They also become ignored Common Name values regardless of the
GODEBUG=x509ignoreCN=X value, because we have to ignore invalid
hostnames in Common Name for #24151. The error message automatically
accounts for this, and doesn't suggest the environment variable. You
don't get to use a legacy deprecated field AND invalid hostnames.

(While at it, also consider wildcards in VerifyHostname inputs as
invalid hostnames, not that it should change any observed behavior.)

Change-Id: Iecdee8927df50c1d9daf904776b051de9f5e76ad
Reviewed-on: https://go-review.googlesource.com/c/go/+/231380
Run-TryBot: Filippo Valsorda <filippo@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Katie Hockman <katie@golang.org>

0 files changed, 0 insertions, 0 deletions