On Thu, Mar 3, 2016 at 10:49 AM, Adam Langley <a...@imperialviolet.org> wrote:
> The Server Name Indication (SNI) extension in TLS has a provision to > provide names other than host names[1]. None have even been defined to > my knowledge, but it's there. > > OpenSSL (and possibly others) have had a long-standing bug[2] (fixed > in master) that means that different types of names will cause an > error. To be clear: I live in a glass house and am not throwing > stones; these things happen. However, it means that a huge fraction of > the TLS deployment will not be able to accept a different name type > should one ever be defined. (This issue might have been caused by the > fact that the original[3] spec didn't define the extension in such a > way that unknown name types could be skipped over.) > > Therefore we (i.e. BoringSSL, and thus Google) are proposing to give > up on this and implement our parser such that the SNI extension is > only allowed to contain a single host name value. (This is compatible > with all known clients.) We're assuming that since this is already the > de-facto reality that there will be little objection. I'm sending this > mostly to record the fact so that, if someone tries to define a new > name type in the future, they won't waste their time. > Note: it's already the case that it's forbidden to send >1 of any given type of name. NSS does not presently enforce this rule but will do so soon. Regardless, I am in favor of this proposal. -Ekr
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