darkfi/net/acceptor.rs
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/* This file is part of DarkFi (https://dark.fi)
*
* Copyright (C) 2020-2025 Dyne.org foundation
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
use std::{
io::ErrorKind,
sync::{
atomic::{AtomicUsize, Ordering::SeqCst},
Arc,
},
};
use log::{error, info, warn};
use smol::Executor;
use url::Url;
use super::{
channel::{Channel, ChannelPtr},
hosts::HostColor,
session::SessionWeakPtr,
transport::{Listener, PtListener},
};
use crate::{
system::{CondVar, Publisher, PublisherPtr, StoppableTask, StoppableTaskPtr, Subscription},
Error, Result,
};
/// Atomic pointer to Acceptor
pub type AcceptorPtr = Arc<Acceptor>;
/// Create inbound socket connections
pub struct Acceptor {
channel_publisher: PublisherPtr<Result<ChannelPtr>>,
task: StoppableTaskPtr,
session: SessionWeakPtr,
conn_count: AtomicUsize,
}
impl Acceptor {
/// Create new Acceptor object.
pub fn new(session: SessionWeakPtr) -> AcceptorPtr {
Arc::new(Self {
channel_publisher: Publisher::new(),
task: StoppableTask::new(),
session,
conn_count: AtomicUsize::new(0),
})
}
/// Start accepting inbound socket connections
pub async fn start(self: Arc<Self>, endpoint: Url, ex: Arc<Executor<'_>>) -> Result<()> {
let datastore =
self.session.upgrade().unwrap().p2p().settings().read().await.p2p_datastore.clone();
// Initialize listener
let listener = Listener::new(endpoint.clone(), datastore).await?;
// Open socket
let ptlistener = listener.listen().await?;
#[cfg(feature = "p2p-tor")]
if endpoint.scheme() == "tor" {
let onion_addr = listener.endpoint().await;
info!("[P2P] Adding {} to external_addrs", onion_addr);
self.session
.upgrade()
.unwrap()
.p2p()
.settings()
.write()
.await
.external_addrs
.push(onion_addr);
}
self.accept(ptlistener, ex);
Ok(())
}
/// Stop accepting inbound socket connections
pub async fn stop(&self) {
// Send stop signal
self.task.stop().await;
}
/// Start receiving network messages.
pub async fn subscribe(self: Arc<Self>) -> Subscription<Result<ChannelPtr>> {
self.channel_publisher.clone().subscribe().await
}
/// Run the accept loop in a new thread and error if a connection problem occurs
fn accept(self: Arc<Self>, listener: Box<dyn PtListener>, ex: Arc<Executor<'_>>) {
let self_ = self.clone();
self.task.clone().start(
self.run_accept_loop(listener, ex.clone()),
|result| self_.handle_stop(result),
Error::NetworkServiceStopped,
ex,
);
}
/// Run the accept loop.
async fn run_accept_loop(
self: Arc<Self>,
listener: Box<dyn PtListener>,
ex: Arc<Executor<'_>>,
) -> Result<()> {
// CondVar used to notify the loop to recheck if new connections can
// be accepted by the listener.
let cv = Arc::new(CondVar::new());
let hosts = self.session.upgrade().unwrap().p2p().hosts();
loop {
// Refuse new connections if we're up to the connection limit
let limit =
self.session.upgrade().unwrap().p2p().settings().read().await.inbound_connections;
if self.clone().conn_count.load(SeqCst) >= limit {
// This will get notified every time an inbound channel is stopped.
// These channels are the channels spawned below on listener.next().is_ok().
// After the notification, we reset the condvar and retry this loop to see
// if we can accept more connections, and if not - we'll be back here.
warn!(target: "net::acceptor::run_accept_loop()", "Reached incoming conn limit, waiting...");
cv.wait().await;
cv.reset();
continue
}
// Now we wait for a new connection.
match listener.next().await {
Ok((stream, url)) => {
// Check if we reject this peer
if hosts.container.contains(HostColor::Black as usize, &url) ||
hosts.block_all_ports(&url)
{
warn!(target: "net::acceptor::run_accept_loop()", "Peer {} is blacklisted", url);
continue
}
// Create the new Channel.
let session = self.session.clone();
let channel = Channel::new(stream, None, url, session).await;
// Increment the connection counter
self.conn_count.fetch_add(1, SeqCst);
// This task will subscribe on the new channel and decrement
// the connection counter. Along with that, it will notify
// the CondVar that might be waiting to allow new connections.
let self_ = self.clone();
let channel_ = channel.clone();
let cv_ = cv.clone();
ex.spawn(async move {
let stop_sub = channel_.subscribe_stop().await?;
stop_sub.receive().await;
self_.conn_count.fetch_sub(1, SeqCst);
cv_.notify();
Ok::<(), crate::Error>(())
})
.detach();
// Finally, notify any publishers about the new channel.
self.channel_publisher.notify(Ok(channel)).await;
}
// As per accept(2) recommendation:
Err(e) if e.raw_os_error().is_some() => match e.raw_os_error().unwrap() {
libc::EAGAIN | libc::ECONNABORTED | libc::EPROTO | libc::EINTR => continue,
libc::ECONNRESET => {
warn!(
target: "net::acceptor::run_accept_loop()",
"[P2P] Connection reset by peer in accept_loop"
);
continue
}
libc::ETIMEDOUT => {
warn!(
target: "net::acceptor::run_accept_loop()",
"[P2P] Connection timed out in accept_loop"
);
continue
}
libc::EPIPE => {
warn!(
target: "net::acceptor::run_accept_loop()",
"[P2P] Broken pipe in accept_loop"
);
continue
}
x => {
warn!(
target: "net::acceptor::run_accept_loop()",
"[P2P] Unhandled OS Error: {} {}", e, x,
);
continue
/*
error!(
target: "net::acceptor::run_accept_loop()",
"[P2P] Acceptor failed listening: {} ({})", e, x,
);
error!(
target: "net::acceptor::run_accept_loop()",
"[P2P] Closing listener loop"
);
return Err(e.into())
*/
}
},
// In case a TLS handshake fails, we'll get this:
Err(e) if e.kind() == ErrorKind::UnexpectedEof => continue,
// Handle ErrorKind::Other
Err(e) if e.kind() == ErrorKind::Other => {
if let Some(inner) = std::error::Error::source(&e) {
if let Some(inner) = inner.downcast_ref::<futures_rustls::rustls::Error>() {
error!(
target: "net::acceptor::run_accept_loop()",
"[P2P] rustls listener error: {:?}", inner,
);
continue
}
}
error!(
target: "net::acceptor::run_accept_loop()",
"[P2P] Unhandled ErrorKind::Other error: {:?}", e,
);
return Err(e.into())
}
// Errors we didn't handle above:
Err(e) => {
error!(
target: "net::acceptor::run_accept_loop()",
"[P2P] Unhandled listener.next() error: {}", e,
);
/*
error!(
target: "net::acceptor::run_accept_loop()",
"[P2P] Closing listener loop"
);
return Err(e.into())
*/
continue
}
}
}
}
/// Handles network errors. Panics if errors pass silently, otherwise broadcasts it
/// to all channel publishers.
async fn handle_stop(self: Arc<Self>, result: Result<()>) {
match result {
Ok(()) => panic!("Acceptor task should never complete without error status"),
Err(err) => self.channel_publisher.notify(Err(err)).await,
}
}
}