pingora 0.8.0

A framework to build fast, reliable and programmable networked systems at Internet scale.
Documentation 
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// Copyright 2026 Cloudflare, Inc.
//
// 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.

use async_trait::async_trait;
use log::debug;

use std::sync::Arc;
use tokio::io::{AsyncReadExt, AsyncWriteExt};
use tokio::select;

use pingora::apps::ServerApp;
use pingora::connectors::TransportConnector;
use pingora::protocols::Stream;
use pingora::server::ShutdownWatch;
use pingora::upstreams::peer::BasicPeer;

pub struct ProxyApp {
    client_connector: TransportConnector,
    proxy_to: BasicPeer,
}

enum DuplexEvent {
    DownstreamRead(usize),
    UpstreamRead(usize),
}

impl ProxyApp {
    pub fn new(proxy_to: BasicPeer) -> Self {
        ProxyApp {
            client_connector: TransportConnector::new(None),
            proxy_to,
        }
    }

    async fn duplex(&self, mut server_session: Stream, mut client_session: Stream) {
        let mut upstream_buf = [0; 1024];
        let mut downstream_buf = [0; 1024];
        loop {
            let downstream_read = server_session.read(&mut upstream_buf);
            let upstream_read = client_session.read(&mut downstream_buf);
            let event: DuplexEvent;
            select! {
                n = downstream_read => event
                    = DuplexEvent::DownstreamRead(n.unwrap()),
                n = upstream_read => event
                    = DuplexEvent::UpstreamRead(n.unwrap()),
            }
            match event {
                DuplexEvent::DownstreamRead(0) => {
                    debug!("downstream session closing");
                    return;
                }
                DuplexEvent::UpstreamRead(0) => {
                    debug!("upstream session closing");
                    return;
                }
                DuplexEvent::DownstreamRead(n) => {
                    client_session.write_all(&upstream_buf[0..n]).await.unwrap();
                    client_session.flush().await.unwrap();
                }
                DuplexEvent::UpstreamRead(n) => {
                    server_session
                        .write_all(&downstream_buf[0..n])
                        .await
                        .unwrap();
                    server_session.flush().await.unwrap();
                }
            }
        }
    }
}

#[async_trait]
impl ServerApp for ProxyApp {
    async fn process_new(
        self: &Arc<Self>,
        io: Stream,
        _shutdown: &ShutdownWatch,
    ) -> Option<Stream> {
        let client_session = self.client_connector.new_stream(&self.proxy_to).await;

        match client_session {
            Ok(client_session) => {
                self.duplex(io, client_session).await;
                None
            }
            Err(e) => {
                debug!("Failed to create client session: {}", e);
                None
            }
        }
    }
}