ws-kit

Generic authenticated typed WebSocket toolkit for Rust — BroadcastHub, RoomManager, heartbeat, and token extraction for Axum.

Features

• axum (default) — Axum ws + tower, TokenExtractor::extract_token(&Parts, _)
• tracing — tracing instrumentation

Quick start

use ws_kit::{hub::BroadcastHub, codec::Codec};
use serde::{Serialize, Deserialize};

#[derive(Clone, Serialize, Deserialize, Debug, PartialEq)]
struct Chat { user: String, body: String }

#[tokio::main]
async fn main() {
    let hub = BroadcastHub::<Chat>::new(1024);
    let mut rx = hub.subscribe();
    hub.broadcast(Chat { user: "alice".into(), body: "hi".into() }).unwrap();
    let msg = rx.recv().await.unwrap();
    assert_eq!(msg.user, "alice");
}

Rooms:

use ws_kit::room::RoomManager;
let m = RoomManager::new();
let room = m.get_or_create("lobby");
room.join("alice");
room.broadcast("hello".to_string()).unwrap();

Token extraction:

use ws_kit::extractor::{TokenExtractor, TokenSourceKind};
let ex = TokenExtractor::default(); // Bearer, ?token=, ?access_token=
let tok = ex.extract_from_parts(Some("Bearer xyz"), None, "token=qry");

Codec:

use ws_kit::codec::Codec;
use serde::{Serialize, Deserialize};
#[derive(Serialize, Deserialize, PartialEq, Debug)] struct Msg { t: String }
let m = Msg { t: "hi".into() };
let s = m.encode();
let d = Msg::decode(&s).unwrap();

Concurrency testing

The connection counter's atomic logic (bounded increment CAS loop, saturating decrement) is model-checked with loom under --cfg loom — see src/loom_tests.rs:

RUSTFLAGS="--cfg loom" cargo test --release --lib --no-default-features -- loom

(--no-default-features drops the axum stack — tokio-tungstenite does not compile under --cfg loom; the models only need the counter.)

Loom exhaustively explores bounded interleavings and proves: balanced increment/decrement pairs always return the count to zero, the count never goes negative, and the connection limit is never exceeded under races. What loom does not cover: tokio::sync::broadcast and DashMap internals (not loom-compatible) — those are trusted via tokio's and dashmap's own concurrency testing.