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/*
* Copyright 2020 Google LLC
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
//! Filters for processing packets.
mod error;
mod factory;
mod read;
mod registry;
mod set;
mod write;
pub(crate) mod chain;
pub(crate) mod manager;
pub mod capture;
pub mod compress;
pub mod concatenate_bytes;
pub mod debug;
pub mod drop;
pub mod firewall;
pub mod load_balancer;
pub mod local_rate_limit;
pub mod r#match;
pub mod metadata;
pub mod pass;
pub mod token_router;
/// Prelude containing all types and traits required to implement [`Filter`] and
/// [`FilterFactory`].
pub mod prelude {
pub use super::{
ConvertProtoConfigError, CreateFilterArgs, DynFilterFactory, Error, Filter, FilterFactory,
FilterInstance, ReadContext, ReadResponse, WriteContext, WriteResponse,
};
}
// Core Filter types
pub use self::{
error::{ConvertProtoConfigError, Error},
factory::{CreateFilterArgs, DynFilterFactory, FilterFactory, FilterInstance},
read::{ReadContext, ReadResponse},
registry::FilterRegistry,
set::{FilterMap, FilterSet},
write::{WriteContext, WriteResponse},
};
pub(crate) use self::chain::FilterChain;
/// Trait for routing and manipulating packets.
///
/// An implementation of [`Filter`] provides a `read` and a `write` method. Both
/// methods are invoked by the proxy when it consults the filter chain - their
/// arguments contain information about the packet being processed.
/// - `read` is invoked when a packet is received on the local downstream port
/// and is to be sent to an upstream endpoint.
/// - `write` is invoked in the opposite direction when a packet is received
/// from an upstream endpoint and is to be sent to a downstream client.
///
/// **Metrics**
///
/// * `filter_read_duration_seconds` The duration it took for a `filter`'s
/// `read` implementation to execute.
/// * Labels
/// * `filter` The name of the filter being executed.
///
/// * `filter_write_duration_seconds` The duration it took for a `filter`'s
/// `write` implementation to execute.
/// * Labels
/// * `filter` The name of the filter being executed.
pub trait Filter: Send + Sync {
/// [`Filter::read`] is invoked when the proxy receives data from a
/// downstream connection on the listening port.
///
/// This function should return a [`ReadResponse`] containing the array of
/// endpoints that the packet should be sent to and the packet that should
/// be sent (which may be manipulated) as well. If the packet should be
/// rejected, return [`None`]. By default, the context passes
/// through unchanged.
fn read(&self, ctx: ReadContext) -> Option<ReadResponse> {
Some(ctx.into())
}
/// [`Filter::write`] is invoked when the proxy is about to send data to a
/// downstream connection via the listening port after receiving it via one
/// of the upstream Endpoints.
///
/// This function should return an [`WriteResponse`] containing the packet to
/// be sent (which may be manipulated). If the packet should be rejected,
/// return [`None`]. By default, the context passes through unchanged.
fn write(&self, ctx: WriteContext) -> Option<WriteResponse> {
Some(ctx.into())
}
}