[tor-dev] Revisiting prop224 time periods and HS descriptor upload/downloads

[George Kadianakis]

David Goulet <dgoulet at ev0ke.net> writes:

> [ text/plain ]
> On 13 Apr (15:34:54), George Kadianakis wrote:
>> David Goulet <dgoulet at ev0ke.net> writes:
>> 
>> > [ text/plain ]
>> > On 12 Apr (16:01:32), George Kadianakis wrote:
>> >> David Goulet <dgoulet at ev0ke.net> writes:
>> >> 
>> >> > [ text/plain ]
>> >> > On 11 Apr (14:42:02), George Kadianakis wrote:
>> >> >> David Goulet <dgoulet at ev0ke.net> writes:
>> >> >> 
>> >> >> > [ text/plain ]
>> >> >> > On 04 Apr (19:13:39), George Kadianakis wrote:
>> >> >> >> Hello,
>> >> >> >> 
>> >> >> >> during March we discussed the cell formats of prop224:
>> >> >> >>   https://lists.torproject.org/pipermail/tor-dev/2016-March/010534.html
>> >> >> >> 
>> >> >> >> The prop224 topic for this month has to do with the way descriptors get
>> >> >> >> uploaded and downloaded, how this is scheduled using time periods and how the
>> >> >> >> shared randomness subsystem interacts with all that.
>> >> >> >> 
>> >> >> >> <snip>
>
>> 
>> Here are some things left to be done:
>> 
>> - Specify *when* hidden services upload descriptors. Do they do it hourly, or
>>   only when a change has happened. Both approaches leak information to the
>>   HSDir (the former leaks uptime, the latter leaks intro point changes).
>
> I'm more comfortable right now with the HS uploading every RendPostPeriod
> (default: 1 hour). Even if the descriptor content doesn't change, it should
> increment the revision-counter.
>
> I'm more and more convinced that making RendPostPeriod _not_ configurable is
> also something we should do and thus allowing us to have the HSDir use that
> value instead (maybe).
>

Hello,

I pushed some more changes to my `prop224-timeperiods-1` branch.

As discussed above, I specified that HSes should upload their descriptors
periodically here:
  https://gitweb.torproject.org/user/asn/torspec.git/commit/?h=prop224-timeperiods-1&id=c5309b7d6422daea980ed7ff401ec99f4fca58da

>> 
>> - Specify behavior of hidden services and clients with regards to time periods
>>   and the use of SRVs as discussed in
>>     https://lists.torproject.org/pipermail/tor-dev/2016-April/010757.html
>
> I'm happy with your approach if you find mine a bit more complicated. They
> both result in the _same_ behavior anyway. Altough, in terms of code, for each
> SRV value, we need to keep the valid-after and the valid-until time in our SRV
> data structure (which we don't right now with current prop250 code).
>

I also specified the behavior of hidden services and clients in this commit:
  https://gitweb.torproject.org/user/asn/torspec.git/commit/?h=prop224-timeperiods-1&id=e64c87b3685a40704f1108563c1c8341864bb71d

Please let me know how that section can become cleaner if you have any ideas.

I think this covers up the time period related changes for now. If you people
think that my `prop224-timeperiods-1` branch looks good and that I didn't
forget of anything else, I will ask Nick to review it and then merge it to torspec.

Cheers!