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/*
This file is part of gnix (https://codeberg.org/metamuffin/gnix)
which is licensed under the GNU Affero General Public License (version 3); see /COPYING.
Copyright (C) 2025 metamuffin <metamuffin.org>
*/
use super::{cgi::set_cgi_variables, Node, NodeContext, NodeKind, NodeRequest, NodeResponse};
use crate::{config::DynNode, error::ServiceError};
use anyhow::Result;
use futures::Future;
use http::{header::RETRY_AFTER, HeaderValue, Response, StatusCode};
use http_body_util::{combinators::BoxBody, BodyExt};
use log::{error, warn};
use serde::Deserialize;
use std::{
collections::HashMap,
hash::{DefaultHasher, Hash, Hasher},
net::IpAddr,
pin::Pin,
process::Stdio,
sync::Arc,
time::{Duration, Instant},
};
use tokio::{process::Command, spawn, sync::Mutex, time::sleep_until};
pub struct RatelimitKind;
#[derive(Deserialize)]
pub struct RatelimitConfig {
next: DynNode,
#[serde(default)]
identity: IdentityMode,
#[serde(default = "default_max_identities")]
max_identities: usize,
reference_duration: f32,
thresholds: Vec<(usize, LimitMode)>,
}
fn default_max_identities() -> usize {
1 << 16
}
#[derive(Deserialize, Default)]
#[serde(rename_all = "snake_case")]
enum IdentityMode {
Global,
#[default]
SourceAddress,
SourceAddressTrunc {
v4: u8,
v6: u8,
},
Path,
PathQuery,
}
#[derive(Deserialize)]
#[serde(rename_all = "snake_case")]
enum LimitMode {
TooManyRequests,
Exec(String),
}
pub struct Ratelimit {
state: Arc<Mutex<HashMap<u64, IdentityState>>>,
config: RatelimitConfig,
}
struct IdentityState {
counter: usize,
frame_end: Instant,
}
impl NodeKind for RatelimitKind {
fn name(&self) -> &'static str {
"ratelimit"
}
fn instanciate(&self, config: serde_yml::Value) -> Result<Arc<dyn Node>> {
Ok(Arc::new(Ratelimit {
state: Arc::new(Mutex::new(HashMap::new())),
config: serde_yml::from_value::<RatelimitConfig>(config)?,
}))
}
}
impl Node for Ratelimit {
fn handle<'a>(
&'a self,
context: &'a mut NodeContext,
request: NodeRequest,
) -> Pin<Box<dyn Future<Output = Result<NodeResponse, ServiceError>> + Send + Sync + 'a>> {
Box::pin(async move {
let identity_hash = match self.config.identity {
IdentityMode::Global => 0,
IdentityMode::SourceAddress => hash(context.addr.ip()),
IdentityMode::SourceAddressTrunc { v4, v6 } => match context.addr.ip() {
IpAddr::V4(a) => hash(a.to_bits() >> v4),
IpAddr::V6(a) => hash(a.to_bits() >> v6),
},
IdentityMode::Path => hash(request.uri().path()),
IdentityMode::PathQuery => hash(request.uri().path_and_query()),
};
let now = Instant::now();
let (counter, frame_end) = {
let mut state = self.state.lock().await;
if state.len() > self.config.max_identities {
return Err(ServiceError::TooManyIdentities);
}
let istate = state.entry(identity_hash).or_insert_with(|| {
let frame_end = now + Duration::from_secs_f32(self.config.reference_duration);
let state = self.state.clone();
//? How efficient is this? Does it scale better to have a central task?
spawn(async move {
sleep_until(frame_end.into()).await;
state.lock().await.remove(&identity_hash)
});
IdentityState {
counter: 0,
frame_end,
}
});
istate.counter += 1;
(istate.counter, istate.frame_end)
};
for (thres, l) in &self.config.thresholds {
match l {
LimitMode::TooManyRequests => {
if counter > *thres {
let mut r = Response::new(BoxBody::new(
http_body_util::Empty::new().map_err(|x| match x {}),
));
*r.status_mut() = StatusCode::TOO_MANY_REQUESTS;
r.headers_mut().insert(
RETRY_AFTER,
HeaderValue::from_str(&(frame_end - now).as_secs().to_string())
.unwrap(),
);
return Ok(r);
}
}
LimitMode::Exec(path) => {
// Exact comparison so it can only trigger once per frame
if counter == *thres {
let mut command = Command::new(path);
command.stdin(Stdio::null());
set_cgi_variables(&mut command, &request, context);
spawn(async move {
let mut child = match command.spawn() {
Ok(c) => c,
Err(e) => return error!("exec limiter spawn failed: {e}"),
};
match child.wait().await {
Ok(s) if s.success() => (),
Ok(s) => warn!(
"exec limiter failed with code {}",
s.code().unwrap_or_default()
),
Err(e) => warn!("exec limiter failed: {e}"),
}
});
}
}
}
}
self.config.next.handle(context, request).await
})
}
}
fn hash(value: impl Hash) -> u64 {
let mut h = DefaultHasher::default();
value.hash(&mut h);
h.finish()
}
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