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|
use std::collections::HashMap;
use std::net::IpAddr;
use std::time::{Duration, Instant};
use lazy_static::lazy_static;
const PACKETS_PER_SECOND: u64 = 20;
const PACKETS_BURSTABLE: u64 = 5;
const PACKET_COST: u64 = 1_000_000_000 / PACKETS_PER_SECOND;
const MAX_TOKENS: u64 = PACKET_COST * PACKETS_BURSTABLE;
lazy_static! {
pub static ref GC_INTERVAL: Duration = Duration::new(1, 0);
}
struct Entry {
pub last_time: Instant,
pub tokens: u64,
}
pub struct RateLimiter {
garbage_collect: Instant,
table: HashMap<IpAddr, Entry>,
}
impl RateLimiter {
pub fn new() -> Self {
RateLimiter {
garbage_collect: Instant::now(),
table: HashMap::new(),
}
}
pub fn allow(&mut self, addr: &IpAddr) -> bool {
// check for garbage collection
if self.garbage_collect.elapsed() > *GC_INTERVAL {
self.handle_gc();
}
// update existing entry
if let Some(entry) = self.table.get_mut(addr) {
// add tokens earned since last time
entry.tokens =
MAX_TOKENS.min(entry.tokens + u64::from(entry.last_time.elapsed().subsec_nanos()));
entry.last_time = Instant::now();
// subtract cost of packet
if entry.tokens > PACKET_COST {
entry.tokens -= PACKET_COST;
return true;
} else {
return false;
}
}
// add new entry
self.table.insert(
*addr,
Entry {
last_time: Instant::now(),
tokens: MAX_TOKENS - PACKET_COST,
},
);
true
}
fn handle_gc(&mut self) {
self.table
.retain(|_, ref mut entry| entry.last_time.elapsed() <= *GC_INTERVAL);
}
}
#[cfg(test)]
mod tests {
use super::*;
use std;
struct Result {
allowed: bool,
text: &'static str,
wait: Duration,
}
#[test]
fn test_ratelimiter() {
let mut ratelimiter = RateLimiter::new();
let mut expected = vec![];
let ips = vec![
"127.0.0.1".parse().unwrap(),
"192.168.1.1".parse().unwrap(),
"172.167.2.3".parse().unwrap(),
"97.231.252.215".parse().unwrap(),
"248.97.91.167".parse().unwrap(),
"188.208.233.47".parse().unwrap(),
"104.2.183.179".parse().unwrap(),
"72.129.46.120".parse().unwrap(),
"2001:0db8:0a0b:12f0:0000:0000:0000:0001".parse().unwrap(),
"f5c2:818f:c052:655a:9860:b136:6894:25f0".parse().unwrap(),
"b2d7:15ab:48a7:b07c:a541:f144:a9fe:54fc".parse().unwrap(),
"a47b:786e:1671:a22b:d6f9:4ab0:abc7:c918".parse().unwrap(),
"ea1e:d155:7f7a:98fb:2bf5:9483:80f6:5445".parse().unwrap(),
"3f0e:54a2:f5b4:cd19:a21d:58e1:3746:84c4".parse().unwrap(),
];
for _ in 0..PACKETS_BURSTABLE {
expected.push(Result {
allowed: true,
wait: Duration::new(0, 0),
text: "inital burst",
});
}
expected.push(Result {
allowed: false,
wait: Duration::new(0, 0),
text: "after burst",
});
expected.push(Result {
allowed: true,
wait: Duration::new(0, PACKET_COST as u32),
text: "filling tokens for single packet",
});
expected.push(Result {
allowed: false,
wait: Duration::new(0, 0),
text: "not having refilled enough",
});
expected.push(Result {
allowed: true,
wait: Duration::new(0, 2 * PACKET_COST as u32),
text: "filling tokens for 2 * packet burst",
});
expected.push(Result {
allowed: true,
wait: Duration::new(0, 0),
text: "second packet in 2 packet burst",
});
expected.push(Result {
allowed: false,
wait: Duration::new(0, 0),
text: "packet following 2 packet burst",
});
for item in expected {
std::thread::sleep(item.wait);
for ip in ips.iter() {
if ratelimiter.allow(&ip) != item.allowed {
panic!(
"test failed for {} on {}. expected: {}, got: {}",
ip, item.text, item.allowed, !item.allowed
)
}
}
}
}
}
|
