crypto/x509: enforce SAN IA5String encoding restrictions
Extends the IA5String encoding restrictions that are currently applied
to name constraints to dNSName, rfc822Name, and
uniformResourceIdentifier elements of the SAN. The utility function
isIA5String is updated to use unicode.MaxASCII rather than utf8.RuneSelf
as it is somewhat more readable.
Certificates that include these badly encoded names do exist, but are
exceedingly rare. zlint and other linters enforce this encoding and
searching censys.io reveals only three currently trusted certificates
with this particular encoding issue.
Fixes #26362
Change-Id: I7a4f3e165a1754e5b4bfaeabc03e01eb7367f3c9
Reviewed-on: https://go-review.googlesource.com/c/go/+/235078
Run-TryBot: Roland Shoemaker <roland@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Roland Shoemaker <roland@golang.org> Reviewed-by: Filippo Valsorda <filippo@golang.org>