Re: [TLS] DISCUSS on Server Name Indication of 4366-bis

[Michael D'Errico <[e-mail]>]

Joseph Salowey (jsalowey) wrote:
> "3. Server Name Indication
> 
>       struct {
>           NameType name_type;
>           select (name_type) {
>               case host_name: HostName;
>           } name;
>       } ServerName;
> 
>       enum {
>           host_name(0), (255)
>       } NameType;
> 
>       opaque HostName<1..2^16-1>;
> 
>       struct {
>           ServerName server_name_list<1..2^16-1>
>       } ServerNameList;
> 
>  [...]
> 
>    However, for backward compatibility, all future NameTypes
>    MUST begin with a 16-bit length field.
> 
> Can you please clarify what this means?
> I am looking at both ServerName and
> NameType definitions and I don't see what you are talking about."
> 
> Proposed resolution: replace  " However, for backward compatibility, all
> future NameTypes MUST begin with a 16-bit length field." With:
> 
> "The data structure associated with the host_name NameType is a
> variable-length vector that begins with a 16-bit length. For backward
> compatibility, all future data structures associated with new NameTypes
> MUST begin with a 16-bit length field."

This is actually for "forward compatibility" so that new name types
can be skipped by old software that doesn't know about them.

Mike