[tor-dev] Question about hidden services shared by multiple hosts

[Holmes Wilson]

Hi everyone,

We’re working on a peer-to-peer group chat app where peers connect over v3 onion addresses. 

One issue are groups where there are many users but only a few are online in a given moment.  Onion addresses are forever, and existing peers might know every peer in the network, but it will take a while to try connecting to all of them to find one that is online. 

In this case, it seems helpful for one or more peers to share one or more onion addresses that would serve as reliable  “trackers", e.g. 

1. All members know the keypairs for these addresses.
2. All online members ping these addresses at random intervals to say they’re online.
3. If they can’t connect to an address, they start hosting it themselves.

We’re going to start testing it, but we’re wondering if folks here know the likely outcome of trying to “share” hosting of an onion service in this spontaneous-volunteer sort of way and if there are downsides.

I *think* the most important question is how long it takes for the network to stop routing incoming traffic to an offline client when there’s an online one available. How long will the address likely be unreachable in one of these transition moments, assuming some peer immediately detects that a “tracker” onion address has gone offline and begins hosting it themselves? (And does this question make sense?)

Thanks!

Holmes