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


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.


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.


pub use isolation::IsolationToken;


Facilities to build circuits directly, instead of via a circuit manager.

Types related to stream isolation

Code to construct paths through the Tor network


A Circuit Manager (CircMgr) manages a set of circuits, returning them when they’re suitable, and launching them if they don’t already exist.

Configuration for circuit timeouts, expiration, and so on.

A stream of SkewEstimate events.

A unique cryptographic identifier for a selected guard or fallback directory.

Rules for building paths over the network.

Configuration for preemptive circuits.

An estimate of how skewed our clock is, plus a summary of why we think so.

A port that we want to connect to as a client.

Set of requested target ports, mostly for use in error reporting


Represents what we know about the Tor network.

An error returned while looking up or building a circuit

An activity that can succeed or fail, and whose success or failure can be attributed to a guard.


Configuration for a circuit manager

Type Definitions

A Result type as returned from this crate.