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// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0
use crate::{
event::{api::SocketAddress, IntoEvent, Timestamp},
inet,
};
/// Outcome describes how the library should proceed on a connection attempt. The implementor will
/// use information from the ConnectionAttempt object to determine how the library should handle
/// the connection attempt
#[non_exhaustive]
#[derive(Clone, Debug, Eq, PartialEq)]
pub enum Outcome {
/// Allow the connection to continue
///
/// Use `Outcome::allow()` to construct this variant
#[non_exhaustive]
Allow,
/// Defer the connection by sending a Retry packet
///
/// Use `Outcome::retry()` to construct this variant
#[non_exhaustive]
Retry,
/// Silently drop the connection attempt
///
/// Use `Outcome::drop()` to construct this variant
#[non_exhaustive]
Drop,
/// Cleanly close the connection
///
/// Use `Outcome::close()` to construct this variant
#[non_exhaustive]
Close,
}
impl Outcome {
/// Allow the connection to continue
pub fn allow() -> Self {
Self::Allow
}
/// Defer the connection by sending a Retry packet
pub fn retry() -> Self {
Self::Retry
}
/// Silently drop the connection attempt
pub fn drop() -> Self {
Self::Drop
}
/// Cleanly close the connection
pub fn close() -> Self {
Self::Close
}
}
/// A ConnectionAttempt holds information about the state of endpoint receiving a connect, along
/// with information about the connection. This can be used to make decisions about the Outcome of
/// an attempted connection
#[non_exhaustive]
#[derive(Debug)]
pub struct ConnectionAttempt<'a> {
/// Number of handshakes the have begun but not completed
pub inflight_handshakes: usize,
/// Number of open connections
pub connection_count: usize,
/// The unverified address of the connecting peer
/// This address comes from the datagram
pub remote_address: SocketAddress<'a>,
pub timestamp: Timestamp,
}
impl<'a> ConnectionAttempt<'a> {
#[doc(hidden)]
pub fn new(
inflight_handshakes: usize,
connection_count: usize,
remote_address: &'a inet::SocketAddress,
timestamp: Timestamp,
) -> Self {
Self {
inflight_handshakes,
connection_count,
remote_address: remote_address.into_event(),
timestamp,
}
}
}
pub trait Limiter: 'static + Send {
/// This trait is used to determine the outcome of connection attempts on an endpoint. The
/// implementor returns an Outcome based on the ConnectionAttempt, or other information that the
/// implementor may have.
///
/// ```rust
/// # mod s2n_quic { pub mod provider { pub mod endpoint_limits { pub use s2n_quic_core::endpoint::limits::*; } } }
/// use s2n_quic::provider::endpoint_limits::{Limiter, ConnectionAttempt, Outcome};
///
/// struct MyEndpointLimits {
/// handshake_limit: usize,
/// delay: core::time::Duration,
/// }
///
/// impl Limiter for MyEndpointLimits {
/// fn on_connection_attempt(&mut self, info: &ConnectionAttempt) -> Outcome {
/// if info.inflight_handshakes > self.handshake_limit {
/// Outcome::retry()
/// } else {
/// Outcome::allow()
/// }
/// }
/// }
/// ```
fn on_connection_attempt(&mut self, info: &ConnectionAttempt) -> Outcome;
}