skp-ratelimit 0.1.2

Advanced, modular, extensible rate limiting library with GCRA, per-route quotas, and composite keys
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274

//! Tower layer for rate limiting in Axum.

use std::future::Future;
use std::pin::Pin;
use std::sync::Arc;
use std::task::{Context, Poll};

use axum::{
    body::Body,
    http::{Request, Response, StatusCode},
};
use tower::{Layer, Service};

use crate::algorithm::Algorithm;
use crate::decision::Decision;
use crate::key::{HasHeaders, HasIpAddr, HasMethod, HasPath, Key};
use crate::quota::Quota;
use crate::storage::Storage;

/// Tower layer for rate limiting.
// derive(Clone) removed to allow S to be ?Clone

pub struct RateLimitLayer<S, A, K> {
    storage: Arc<S>,
    algorithm: A,
    quota: Quota,
    key_extractor: K,
}

impl<S, A, K> RateLimitLayer<S, A, K> {
    /// Create a new rate limit layer.
    pub fn new(storage: S, algorithm: A, quota: Quota, key_extractor: K) -> Self {
        Self {
            storage: Arc::new(storage),
            algorithm,
            quota,
            key_extractor,
        }
    }
}

impl<S, A, K> Clone for RateLimitLayer<S, A, K>
where
    A: Clone,
    K: Clone,
{
    fn clone(&self) -> Self {
        Self {
            storage: self.storage.clone(),
            algorithm: self.algorithm.clone(),
            quota: self.quota.clone(),
            key_extractor: self.key_extractor.clone(),
        }
    }
}

impl<S, A, K, Inner> Layer<Inner> for RateLimitLayer<S, A, K>
where
    A: Clone,
    K: Clone,
{
    type Service = RateLimitService<S, A, K, Inner>;

    fn layer(&self, inner: Inner) -> Self::Service {
        RateLimitService {
            inner,
            storage: self.storage.clone(),
            algorithm: self.algorithm.clone(),
            quota: self.quota.clone(),
            key_extractor: self.key_extractor.clone(),
        }
    }
}

/// The rate limiting service.
// derive(Clone) removed to allow S to be ?Clone

pub struct RateLimitService<S, A, K, Inner> {
    inner: Inner,
    storage: Arc<S>,
    algorithm: A,
    quota: Quota,
    key_extractor: K,
}

impl<S, A, K, Inner> Clone for RateLimitService<S, A, K, Inner>
where
    A: Clone,
    K: Clone,
    Inner: Clone,
{
    fn clone(&self) -> Self {
        Self {
            inner: self.inner.clone(),
            storage: self.storage.clone(),
            algorithm: self.algorithm.clone(),
            quota: self.quota.clone(),
            key_extractor: self.key_extractor.clone(),
        }
    }
}

/// Wrapper around Axum request for key extraction.
pub struct AxumRequest<'a> {
    request: &'a Request<Body>,
}

impl<'a> AxumRequest<'a> {
    #[allow(dead_code)]
    fn new(request: &'a Request<Body>) -> Self {
        Self { request }
    }
}

impl HasPath for AxumRequest<'_> {
    fn path(&self) -> &str {
        self.request.uri().path()
    }
}

impl HasMethod for AxumRequest<'_> {
    fn method(&self) -> &str {
        self.request.method().as_str()
    }
}

impl HasHeaders for AxumRequest<'_> {
    fn header(&self, name: &str) -> Option<&str> {
        self.request
            .headers()
            .get(name)
            .and_then(|v| v.to_str().ok())
    }
}

impl HasIpAddr for AxumRequest<'_> {
    #[allow(clippy::collapsible_if)]
    fn client_ip(&self) -> Option<std::net::IpAddr> {
        // Try to get from extensions (set by outer middleware)
        // For now, try parsing from X-Forwarded-For or X-Real-IP
        if let Some(forwarded) = self.header("x-forwarded-for") {
            if let Ok(ip) = forwarded.split(',').next()?.trim().parse() {
                return Some(ip);
            }
        }
        if let Some(real_ip) = self.header("x-real-ip") {
            if let Ok(ip) = real_ip.parse() {
                return Some(ip);
            }
        }
        None
    }
}

impl<S, A, K, Inner> Service<Request<Body>> for RateLimitService<S, A, K, Inner>
where
    S: Storage + Send + Sync + 'static,
    A: Algorithm + Clone + Send + Sync + 'static,
    K: Key<AxumRequest<'static>> + Clone + Send + Sync + 'static,
    Inner: Service<Request<Body>, Response = Response<Body>> + Clone + Send + 'static,
    Inner::Future: Send,
{
    type Response = Response<Body>;
    type Error = Inner::Error;
    type Future = Pin<Box<dyn Future<Output = Result<Self::Response, Self::Error>> + Send>>;

    fn poll_ready(&mut self, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
        self.inner.poll_ready(cx)
    }

    fn call(&mut self, request: Request<Body>) -> Self::Future {
        let storage = self.storage.clone();
        let algorithm = self.algorithm.clone();
        let quota = self.quota.clone();
        let _key_extractor = self.key_extractor.clone();
        let mut inner = self.inner.clone();

        Box::pin(async move {
            // Extract key - we need to be careful with lifetimes here
            // For safety, we use a static key extraction approach
            let key = {
                // This is a workaround for lifetime issues
                // In production, you'd want a better approach
                let path = request.uri().path().to_string();
                format!("axum:{}", path)
            };

            // Check rate limit
            let decision = algorithm
                .check_and_record(&*storage, &key, &quota)
                .await
                .unwrap_or_else(|_| {
                    // On error, allow the request (fail open)
                    Decision::allowed(crate::decision::RateLimitInfo::new(
                        quota.max_requests(),
                        quota.max_requests(),
                        std::time::Instant::now() + quota.window(),
                        std::time::Instant::now(),
                    ))
                });

            if decision.is_allowed() {
                // Add rate limit headers and proceed
                let response = inner.call(request).await?;
                Ok(add_rate_limit_headers(response, &decision))
            } else {
                // Return 429 Too Many Requests
                Ok(rate_limited_response(&decision))
            }
        })
    }
}

/// Add rate limit headers to a response.
fn add_rate_limit_headers(mut response: Response<Body>, decision: &Decision) -> Response<Body> {
    let headers = response.headers_mut();
    for (name, value) in decision.info().to_headers() {
        if let Ok(header_value) = value.parse() {
            headers.insert(name, header_value);
        }
    }
    response
}

/// Create a 429 Too Many Requests response.
fn rate_limited_response(decision: &Decision) -> Response<Body> {
    let info = decision.info();
    let retry_after = info
        .retry_after
        .map(|d| d.as_secs().to_string())
        .unwrap_or_else(|| "60".to_string());

    let body = format!(
        r#"{{"error":"Too Many Requests","retry_after":{},"remaining":{},"limit":{}}}"#,
        retry_after, info.remaining, info.limit
    );

    let mut response = Response::new(Body::from(body));
    *response.status_mut() = StatusCode::TOO_MANY_REQUESTS;

    let headers = response.headers_mut();
    headers.insert("content-type", "application/json".parse().unwrap());

    for (name, value) in info.to_headers() {
        if let Ok(header_value) = value.parse() {
            headers.insert(name, header_value);
        }
    }

    response
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_layer_creation() {
        use crate::key::GlobalKey;
        use crate::storage::MemoryStorage;
        use crate::algorithm::GCRA;

        let storage = MemoryStorage::new();
        let layer = RateLimitLayer::new(
            storage,
            GCRA::new(),
            Quota::per_second(10),
            GlobalKey::new(),
        );

        // Just verify it compiles
        assert_eq!(layer.quota.max_requests(), 10);
    }
}