History

eta 197816d14c Completely overhaul the tor-proto circuit reactor Rather like `e8e9699c3c` ("Get rid of tor-proto's ChannelImpl, and use the reactor more instead"), this admittedly rather large commit refactors the way circuits in `tor-proto` work, centralising all of the logic in one large nonblocking reactor which other things send messages into and out of, instead of having a bunch of `-Impl` types that are protected by mutexes. Congestion control becomes a lot simpler with this refactor, since the reactor can manage both stream- and circuit-level congestion control unilaterally without having to share this information with consumers, meaning we can get rid of some locks. The way streams work also changes, in order to facilitate better handling of backpressure / fairness between streams: each stream now has a set of channels to send and receive messages over, instead of sending relay cells directly onto the channel (now, the reactor pulls messages off each stream in each map, and tries to avoid doing so if it won't be able to forward them yet). Additionally, a lot of "close this circuit / stream" messages aren't required any more, since that state is simply indicated by one end of a channel going away. This should make cleanup a lot less brittle. Getting all of this to work involved writing a fair deal of intricate nonblocking code in Reactor::run_once that tries very hard to be mindful of making backpressure work correctly (and congestion control); the old code could get away with having tasks .await on things, but the new reactor can't really do this (as it'd lock the reactor up), so has to do everything in a nonblocking manner.		2021-11-12 15:04:24 +00:00
..
src	Completely overhaul the tor-proto circuit reactor	2021-11-12 15:04:24 +00:00
Cargo.toml	Document that the "experimental-api" feature is not semver-covered.	2021-11-11 10:44:24 -05:00
README.md	Update our disclaimers and limitations sections.	2021-10-27 11:13:46 -04:00

README.md

tor-circmgr

tor-circmgr: circuits through the Tor network on demand.

Overview

This crate is part of Arti, a project to implement Tor in Rust.

In Tor, a circuit is an encrypted multi-hop tunnel over multiple relays. This crate's purpose, long-term, is to manage a set of circuits for a client. It should construct circuits in response to a client's needs, and preemptively construct circuits so as to anticipate those needs. If a client request can be satisfied with an existing circuit, it should return that circuit instead of constructing a new one.

Limitations

But for now, this tor-circmgr code is extremely preliminary; its data structures are all pretty bad, and it's likely that the API is wrong too.

License: MIT OR Apache-2.0