On Fri, Aug 11, 2017 at 9:31 PM, Álvaro Hernández Tortosa
<aht@8kdata.com> wrote:
> On 11/08/17 13:18, Michael Paquier wrote:
>> On Fri, Aug 11, 2017 at 3:50 PM, Álvaro Hernández Tortosa
>> <aht@8kdata.com> wrote:
>>>> Relatedly, the SCRAM specification doesn't appear to allow omitting the
>>>> user name in this manner. Why don't we just send the actual user name,
>>>> even though it's redundant with the startup message?
>>
>> The problem is where a username includes characters as a comma or '=',
>> which can be avoided if the string is in UTF-8 as the username is
>> prepared with SASLprep before being used in the SASL exchange, but we
>> have no way now to be sure now that the string is actually in UTF-8.
>> If at some point we decide that only things using UTF-8 are good to be
>> used during authentication, using the username in the exchange
>> messages instead of the one in the startup packet would be fine and
>> actually better IMO in the long term. Please note that the
>> specification says that both the username and the password must be
>> encoded in UTF-8, so we are not completely compliant here. If there is
>> something to address, that would be this part.
>
> The reason why the username is ignored, unless I'm wrong, is not exactly
> that it is already sent. It is that Postgres does not restrict usernames to
> be UTF-8 only, while SCRAM does. As such, if a username would not be UTF-8,
> it will not be sent reliably over SCRAM.
That's basically the point I was making. Note that I would not be
against Postgres forcing strings to be in UTF-8. Now things are fuzzy
because of the lack of restrictions.
>>> If there's a clear meaning about ignoring the user here, why not
>>> settle
>>> on something like the "*"? It's not going to change the world sending a
>>> few
>>> bytes less on initialization, but I guess it doesn't hurt either...
>>
>> I am not sure either that '*' would be that much helpful. Requiring
>> that things are in UTF-8 would be more compliant with the original
>> RFC.
>
> But we really don't need to send the username, since Postgres already
> knows it (and that accommodates for non UTF-8 usernames). So why bother?
> Just sending something like "*" (which is UTF-8 and produces the same value
> under Saslprep) should be enough. I think the idea of ignoring the username
> is pretty neat, but maybe a "standard" like "send me an asterisk here" could
> be even better than leaving it empty.
Personally I don't see much difference between both, so I'd rather
leave things as they are now.
--
Michael