347 lines
14 KiB
Rust
347 lines
14 KiB
Rust
use std::{
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collections::HashSet,
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future::Future,
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net::SocketAddr,
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pin::Pin,
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sync::{Arc, Mutex},
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task::{Context, Poll},
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};
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use chrono::Utc;
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use futures::{
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channel::{mpsc, oneshot},
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prelude::*,
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};
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use tokio::net::TcpStream;
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use tokio_util::codec::Framed;
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use tower::Service;
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use tracing::{span, Level};
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use tracing_futures::Instrument;
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use zebra_chain::types::BlockHeight;
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use crate::{
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constants,
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protocol::{
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external::{types::*, Codec, Message},
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internal::{Request, Response},
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},
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types::MetaAddr,
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BoxedStdError, Config,
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};
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use super::{Client, Connection, ErrorSlot, HandshakeError};
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/// A [`Service`] that handshakes with a remote peer and constructs a
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/// client/server pair.
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pub struct Handshake<S> {
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config: Config,
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internal_service: S,
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timestamp_collector: mpsc::Sender<MetaAddr>,
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nonces: Arc<Mutex<HashSet<Nonce>>>,
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}
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impl<S: Clone> Clone for Handshake<S> {
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fn clone(&self) -> Self {
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Handshake {
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config: self.config.clone(),
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internal_service: self.internal_service.clone(),
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timestamp_collector: self.timestamp_collector.clone(),
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nonces: self.nonces.clone(),
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}
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}
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}
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impl<S> Handshake<S>
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where
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S: Service<Request, Response = Response, Error = BoxedStdError> + Clone + Send + 'static,
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S::Future: Send,
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{
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/// Construct a new `PeerConnector`.
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pub fn new(
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config: Config,
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internal_service: S,
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timestamp_collector: mpsc::Sender<MetaAddr>,
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) -> Self {
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// XXX this function has too many parameters, but it's not clear how to
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// do a nice builder as all fields are mandatory. Could have Builder1,
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// Builder2, ..., with Builder1::with_config() -> Builder2;
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// Builder2::with_internal_service() -> ... or use Options in a single
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// Builder type or use the derive_builder crate.
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Handshake {
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config,
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internal_service,
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timestamp_collector,
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nonces: Arc::new(Mutex::new(HashSet::new())),
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}
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}
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}
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impl<S> Service<(TcpStream, SocketAddr)> for Handshake<S>
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where
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S: Service<Request, Response = Response, Error = BoxedStdError> + Clone + Send + 'static,
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S::Future: Send,
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{
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type Response = Client;
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type Error = BoxedStdError;
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type Future =
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Pin<Box<dyn Future<Output = Result<Self::Response, Self::Error>> + Send + 'static>>;
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fn poll_ready(&mut self, _cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
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Poll::Ready(Ok(()))
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}
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fn call(&mut self, req: (TcpStream, SocketAddr)) -> Self::Future {
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let (tcp_stream, addr) = req;
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let connector_span = span!(Level::INFO, "connector", addr = ?addr);
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// set parent: None for the peer connection span, as it should exist
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// independently of its creation source (inbound connection, crawler,
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// initial peer, ...)
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let connection_span = span!(parent: None, Level::INFO, "peer", addr = ?addr);
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// Clone these upfront, so they can be moved into the future.
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let nonces = self.nonces.clone();
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let internal_service = self.internal_service.clone();
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let timestamp_collector = self.timestamp_collector.clone();
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let user_agent = self.config.user_agent.clone();
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let network = self.config.network;
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let fut = async move {
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debug!("connecting to remote peer");
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let mut stream =
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Framed::new(tcp_stream, Codec::builder().for_network(network).finish());
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let local_nonce = Nonce::default();
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nonces
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.lock()
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.expect("mutex should be unpoisoned")
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.insert(local_nonce);
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let version = Message::Version {
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version: constants::CURRENT_VERSION,
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services: PeerServices::NODE_NETWORK,
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timestamp: Utc::now(),
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address_recv: (PeerServices::NODE_NETWORK, addr),
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// TODO: when we've implemented block and transaction relaying,
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// send our configured address to the peer
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address_from: (PeerServices::NODE_NETWORK, "0.0.0.0:8233".parse().unwrap()),
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nonce: local_nonce,
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user_agent,
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// XXX eventually the `PeerConnector` will need to have a handle
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// for a service that gets the current block height. Among other
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// things we need it to reject peers who don't know about the
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// current protocol epoch.
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start_height: BlockHeight(0),
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relay: false,
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};
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debug!(?version, "sending initial version message");
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stream.send(version).await?;
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let remote_msg = stream
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.next()
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.await
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.ok_or_else(|| HandshakeError::ConnectionClosed)??;
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// Check that we got a Version and destructure its fields into the local scope.
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debug!(?remote_msg, "got message from remote peer");
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let (remote_nonce, remote_services, remote_version) = if let Message::Version {
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nonce,
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services,
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version,
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..
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} = remote_msg
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{
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(nonce, services, version)
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} else {
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return Err(HandshakeError::UnexpectedMessage(Box::new(remote_msg)));
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};
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// Check for nonce reuse, indicating self-connection.
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let nonce_reuse = {
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let mut locked_nonces = nonces.lock().expect("mutex should be unpoisoned");
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let nonce_reuse = locked_nonces.contains(&remote_nonce);
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// Regardless of whether we observed nonce reuse, clean up the nonce set.
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locked_nonces.remove(&local_nonce);
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nonce_reuse
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};
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if nonce_reuse {
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return Err(HandshakeError::NonceReuse);
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}
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stream.send(Message::Verack).await?;
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let remote_msg = stream
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.next()
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.await
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.ok_or_else(|| HandshakeError::ConnectionClosed)??;
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if let Message::Verack = remote_msg {
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debug!("got verack from remote peer");
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} else {
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return Err(HandshakeError::UnexpectedMessage(Box::new(remote_msg)));
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}
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// XXX in zcashd remote peer can only send one version message and
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// we would disconnect here if it received a second one. Is it even possible
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// for that to happen to us here?
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// TODO: Reject incoming connections from nodes that don't know about the current epoch.
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// zcashd does this:
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// const Consensus::Params& consensusParams = chainparams.GetConsensus();
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// auto currentEpoch = CurrentEpoch(GetHeight(), consensusParams);
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// if (pfrom->nVersion < consensusParams.vUpgrades[currentEpoch].nProtocolVersion)
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//
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// For approximately 1.5 days before a network upgrade, we also need to:
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// - avoid old peers, and
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// - prefer updated peers.
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// For example, we could reject old peers with probability 0.5.
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//
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// At the network upgrade, we also need to disconnect from old peers.
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// TODO: replace MIN_NETWORK_UPGRADE with
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// NetworkUpgrade::current(network, height) where network is
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// the configured network, and height is the best tip's block
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// height.
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if remote_version < Version::min_version(network, constants::MIN_NETWORK_UPGRADE) {
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// Disconnect if peer is using an obsolete version.
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return Err(HandshakeError::ObsoleteVersion(remote_version));
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}
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// Set the connection's version to the minimum of the received version or our own.
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let negotiated_version = std::cmp::min(remote_version, constants::CURRENT_VERSION);
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// Reconfigure the codec to use the negotiated version.
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//
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// XXX The tokio documentation says not to do this while any frames are still being processed.
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// Since we don't know that here, another way might be to release the tcp
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// stream from the unversioned Framed wrapper and construct a new one with a versioned codec.
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let bare_codec = stream.codec_mut();
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bare_codec.reconfigure_version(negotiated_version);
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debug!("constructing client, spawning server");
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// These channels should not be cloned more than they are
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// in this block, see constants.rs for more.
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let (server_tx, server_rx) = mpsc::channel(0);
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let (shutdown_tx, shutdown_rx) = oneshot::channel();
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let slot = ErrorSlot::default();
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let client = Client {
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shutdown_tx: Some(shutdown_tx),
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server_tx: server_tx.clone(),
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error_slot: slot.clone(),
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};
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let (peer_tx, peer_rx) = stream.split();
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// Instrument the peer's rx and tx streams.
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let peer_tx = peer_tx.with(move |msg: Message| {
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// Add a metric for outbound messages.
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// XXX add a dimension tagging message metrics by type
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metrics::counter!("peer.outbound_messages", 1, "addr" => addr.to_string());
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// We need to use future::ready rather than an async block here,
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// because we need the sink to be Unpin, and the With<Fut, ...>
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// returned by .with is Unpin only if Fut is Unpin, and the
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// futures generated by async blocks are not Unpin.
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future::ready(Ok(msg))
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});
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let peer_rx = peer_rx
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.then(move |msg| {
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// Add a metric for inbound messages and fire a timestamp event.
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let mut timestamp_collector = timestamp_collector.clone();
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async move {
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if msg.is_ok() {
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// XXX add a dimension tagging message metrics by type
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metrics::counter!(
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"inbound_messages",
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1,
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"addr" => addr.to_string(),
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);
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use futures::sink::SinkExt;
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let _ = timestamp_collector
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.send(MetaAddr {
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addr,
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services: remote_services,
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last_seen: Utc::now(),
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})
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.await;
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}
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msg
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}
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})
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.boxed();
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use super::connection;
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let server = Connection {
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state: connection::State::AwaitingRequest,
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svc: internal_service,
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client_rx: server_rx,
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error_slot: slot,
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peer_tx,
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request_timer: None,
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};
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tokio::spawn(
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server
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.run(peer_rx)
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.instrument(connection_span.clone())
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.boxed(),
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);
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let heartbeat_span = tracing::debug_span!(parent: connection_span, "heartbeat");
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tokio::spawn(
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async move {
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use super::client::ClientRequest;
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use futures::future::Either;
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let mut shutdown_rx = shutdown_rx;
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let mut server_tx = server_tx;
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let mut interval_stream = tokio::time::interval(constants::HEARTBEAT_INTERVAL);
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loop {
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let shutdown_rx_ref = Pin::new(&mut shutdown_rx);
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match future::select(interval_stream.next(), shutdown_rx_ref).await {
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Either::Left(_) => {
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// We don't wait on a response because heartbeats are checked
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// internally to the connection logic, we just need a separate
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// task (this one) to generate them.
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let (request_tx, _) = oneshot::channel();
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if server_tx
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.send(ClientRequest {
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request: Request::Ping(Nonce::default()),
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tx: request_tx,
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span: tracing::Span::current(),
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})
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.await
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.is_err()
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{
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return;
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}
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}
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Either::Right(_) => return, // got shutdown signal
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}
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}
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}
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.instrument(heartbeat_span)
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.boxed(),
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);
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Ok(client)
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};
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// Spawn a new task to drive this handshake.
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tokio::spawn(fut.instrument(connector_span))
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// This is required to get error types to line up.
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// Probably there's a nicer way to express this using combinators.
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.map(|x| match x {
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Ok(Ok(client)) => Ok(client),
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Ok(Err(handshake_err)) => Err(handshake_err.into()),
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Err(join_err) => Err(join_err.into()),
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})
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.boxed()
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}
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}
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