Multiplex - one snowflake proxy should be able to support multiple clients

added anti-censorship-roadmap-september in Legacy / Trac component::circumvention/snowflake in Legacy / Trac points::2 in Legacy / Trac priority::medium in Legacy / Trac resolution::fixed in Legacy / Trac severity::normal in Legacy / Trac snowflake in Legacy / Trac sponsor::28-can in Legacy / Trac status::closed in Legacy / Trac tor-pt in Legacy / Trac type::defect in Legacy / Trac labels

Dcf points out that this ticket isn't as urgent as it might seem, (a) because the headless proxy-go can already handle multiple clients at once, and (b) because the vision is that we'll have way way more snowflakes than clients, so most snowflakes will be idle most of the time, so the chances of a collision (more than one client sent to the same snowflake) are low.

I buy this logic in the short term, but it still seems to me that the broker design will get cleaner if the browser snowflakes can handle whichever clients try to use them, even if two show up together.

Trac:
Sponsor: N/A to Sponsor19
Keywords: N/A deleted, snowflake tor-pt added

Adding the keyword to mark everything that didn't fit into the time for sponsor 19.

Trac:
Keywords: snowflake tor-pt deleted, ex-sponsor-19, snowflake, tor-pt added

Moving from Sponsor 19 to Sponsor 28.

Trac:
Sponsor: Sponsor19 to Sponsor28-can

Trac:
Cc: dcf, arlolra to dcf, arlolra, cohosh
Keywords: ex-sponsor-19 deleted, anti-censorship-roadmap-september added

Trac:
Points: N/A to 2

Okay so it turns out the multiplexing just works now that legacy/trac#31310 (moved) is out the way and we're using the existence of proxypairs to signal how many slots we have.

I did just a small touch-up of the code here to go with a more meaningful variable name that was going unused.

I tested this in snowbox by setting the maxNumClients to values other than 1 and it works great. However, I don't think we should change this yet as our problems right now are definitely not that we have too few browser-based proxies.

Trac:
Status: new to needs_review

I should add that when we decide we want to increase the number of clients for browser proxies, we will probably want to make UI changes to allow users to modify the config. Again, I don't want to push out those changes yet until we sort out some of the network health issues we're seeing.