• English

      • Rate Limiting

      Middleware providing rate limiting functionality.

      Key Features

      • RateIssuer provides an abstraction for identifying visitor keys. RemoteIpIssuer is one of its implementations, which determines visitors based on their IP addresses. Keys are not necessarily strings; any type satisfying the Hash + Eq + Send + Sync + 'static constraints can serve as a key.

      • RateGuard offers an abstraction for rate limiting algorithms. Default implementations include fixed window (FixedGuard) and sliding window (SlidingGuard).

      • RateStore provides data storage operations. MokaStore is a built-in in-memory cache implementation based on moka. You can also define your own implementation.

      • RateLimiter is a struct implementing Handler, which includes a skipper field to specify requests that should bypass rate limiting. By default, none_skipper is used, meaning no requests are skipped.

      • QuotaGetter provides an abstraction for retrieving quotas. It fetches a quota object based on the visitor's Key, allowing user quotas and other configurations to be stored in databases and dynamically modified or retrieved.

      Example Code

      Static Quota Example

      main.rs
      Cargo.toml
      use salvo::prelude::*;
use salvo::rate_limiter::{BasicQuota, FixedGuard, MokaStore, RateLimiter, RemoteIpIssuer};

#[handler]
async fn hello() -> &'static str {
    "Hello World"
}

#[tokio::main]
async fn main() {
    tracing_subscriber::fmt().init();

    let limiter = RateLimiter::new(
        FixedGuard::new(),
        MokaStore::new(),
        RemoteIpIssuer,
        BasicQuota::per_second(1),
    );
    let router = Router::with_hoop(limiter).get(hello);
    let acceptor = TcpListener::new("0.0.0.0:8698").bind().await;
    Server::new(acceptor).serve(router).await;
}

      Dynamic Quota Example

      main.rs
      Cargo.toml
      use std::borrow::Borrow;
use std::collections::HashMap;
use std::hash::Hash;
use std::sync::LazyLock;

use salvo::Error;
use salvo::prelude::*;
use salvo::rate_limiter::{
    CelledQuota, MokaStore, QuotaGetter, RateIssuer, RateLimiter, SlidingGuard,
};

static USER_QUOTAS: LazyLock<HashMap<String, CelledQuota>> = LazyLock::new(|| {
    let mut map = HashMap::new();
    map.insert("user1".into(), CelledQuota::per_second(1, 1));
    map.insert("user2".into(), CelledQuota::set_seconds(1, 1, 5));
    map.insert("user3".into(), CelledQuota::set_seconds(1, 1, 10));
    map
});

struct UserIssuer;
impl RateIssuer for UserIssuer {
    type Key = String;
    async fn issue(&self, req: &mut Request, _depot: &Depot) -> Option<Self::Key> {
        req.query::<Self::Key>("user")
    }
}

struct CustomQuotaGetter;
impl QuotaGetter<String> for CustomQuotaGetter {
    type Quota = CelledQuota;
    type Error = Error;

    async fn get<Q>(&self, key: &Q) -> Result<Self::Quota, Self::Error>
    where
        String: Borrow<Q>,
        Q: Hash + Eq + Sync,
    {
        USER_QUOTAS
            .get(key)
            .cloned()
            .ok_or_else(|| Error::other("user not found"))
    }
}

#[handler]
async fn limited() -> &'static str {
    "Limited page"
}
#[handler]
async fn home() -> Text<&'static str> {
    Text::Html(HOME_HTML)
}

#[tokio::main]
async fn main() {
    tracing_subscriber::fmt().init();

    let limiter = RateLimiter::new(
        SlidingGuard::new(),
        MokaStore::new(),
        UserIssuer,
        CustomQuotaGetter,
    );
    let router = Router::new()
        .get(home)
        .push(Router::with_path("limited").hoop(limiter).get(limited));
    let acceptor = TcpListener::new("0.0.0.0:8698").bind().await;
    Server::new(acceptor).serve(router).await;
}

static HOME_HTML: &str = r#"
<!DOCTYPE html>
<html>
    <head>
        <title>Rate Limiter Dynamic</title>
    </head>
    <body>
        <h2>Rate Limiter Dynamic</h2>
        <p>
            This example shows how to set limit for different users.
        </p>
        <p>
            <a href="/limited?user=user1" target="_blank">Limited page for user1: 1/second</a>
        </p>
        <p>
            <a href="/limited?user=user2" target="_blank">Limited page for user2: 1/5seconds</a>
        </p>
        <p>
            <a href="/limited?user=user3" target="_blank">Limited page for user3: 1/10seconds</a>
        </p>
    </body>
</html>
"#;