use std::collections::{HashMap, VecDeque}; use std::net::SocketAddr; use std::sync::atomic::{self, AtomicU64}; use std::sync::{Arc, RwLock}; use std::time::{Duration, Instant}; use log::{debug, info, trace, warn}; use serde::{Deserialize, Serialize}; use sodiumoxide::crypto::hash; use crate::message::*; use crate::netapp::*; use crate::proto::*; use crate::NodeID; const CONN_RETRY_INTERVAL: Duration = Duration::from_secs(30); const CONN_MAX_RETRIES: usize = 10; const PING_INTERVAL: Duration = Duration::from_secs(10); const LOOP_DELAY: Duration = Duration::from_secs(1); // -- Protocol messages -- #[derive(Serialize, Deserialize)] struct PingMessage { pub id: u64, pub peer_list_hash: hash::Digest, } impl Message for PingMessage { const KIND: MessageKind = 0x42001000; type Response = PingMessage; } #[derive(Serialize, Deserialize)] struct PeerListMessage { pub list: Vec<(NodeID, SocketAddr)>, } impl Message for PeerListMessage { const KIND: MessageKind = 0x42001001; type Response = PeerListMessage; } // -- Algorithm data structures -- #[derive(Debug)] struct PeerInfo { addr: SocketAddr, state: PeerConnState, last_seen: Option, ping: VecDeque, } #[derive(Copy, Clone, Debug)] pub struct PeerInfoPub { pub id: NodeID, pub addr: SocketAddr, pub state: PeerConnState, pub last_seen: Option, pub avg_ping: Option, pub max_ping: Option, pub med_ping: Option, } // PeerConnState: possible states for our tentative connections to given peer // This module is only interested in recording connection info for outgoing // TCP connections #[derive(Copy, Clone, Debug, PartialEq)] pub enum PeerConnState { // This entry represents ourself Ourself, // We currently have a connection to this peer Connected, // Our next connection tentative (the nth, where n is the first value) // will be at given Instant Waiting(usize, Instant), // A connection tentative is in progress Trying(usize), // We abandonned trying to connect to this peer (too many failed attempts) Abandonned, } struct KnownHosts { list: HashMap, hash: hash::Digest, } impl KnownHosts { fn new() -> Self { let list = HashMap::new(); let hash = Self::calculate_hash(&list); Self { list, hash } } fn update_hash(&mut self) { self.hash = Self::calculate_hash(&self.list); } fn map_into_vec(input: &HashMap) -> Vec<(NodeID, SocketAddr)> { let mut list = Vec::with_capacity(input.len()); for (id, peer) in input.iter() { if peer.state == PeerConnState::Connected || peer.state == PeerConnState::Ourself { list.push((id.clone(), peer.addr)); } } list } fn calculate_hash(input: &HashMap) -> hash::Digest { let mut list = Self::map_into_vec(input); list.sort(); let mut hash_state = hash::State::new(); for (id, addr) in list { hash_state.update(&id[..]); hash_state.update(&format!("{}", addr).into_bytes()[..]); } hash_state.finalize() } } pub struct FullMeshPeeringStrategy { netapp: Arc, known_hosts: RwLock, next_ping_id: AtomicU64, } impl FullMeshPeeringStrategy { pub fn new(netapp: Arc, bootstrap_list: Vec<(NodeID, SocketAddr)>) -> Arc { let mut known_hosts = KnownHosts::new(); for (id, addr) in bootstrap_list { if id != netapp.id { known_hosts.list.insert( id, PeerInfo { addr: addr, state: PeerConnState::Waiting(0, Instant::now()), last_seen: None, ping: VecDeque::new(), }, ); } } let strat = Arc::new(Self { netapp: netapp.clone(), known_hosts: RwLock::new(known_hosts), next_ping_id: AtomicU64::new(42), }); let strat2 = strat.clone(); netapp.add_msg_handler::(move |from: NodeID, ping: PingMessage| { let ping_resp = PingMessage { id: ping.id, peer_list_hash: strat2.known_hosts.read().unwrap().hash, }; debug!("Ping from {}", hex::encode(&from)); async move { ping_resp } }); let strat2 = strat.clone(); netapp.add_msg_handler::( move |_from: NodeID, peer_list: PeerListMessage| { strat2.handle_peer_list(&peer_list.list[..]); let peer_list = KnownHosts::map_into_vec(&strat2.known_hosts.read().unwrap().list); let resp = PeerListMessage { list: peer_list }; async move { resp } }, ); let strat2 = strat.clone(); netapp.on_connected(move |id: NodeID, addr: SocketAddr, is_incoming: bool| { let strat2 = strat2.clone(); tokio::spawn(strat2.on_connected(id, addr, is_incoming)); }); let strat2 = strat.clone(); netapp.on_disconnected(move |id: NodeID, is_incoming: bool| { let strat2 = strat2.clone(); tokio::spawn(strat2.on_disconnected(id, is_incoming)); }); strat } pub async fn run(self: Arc) { loop { // 1. Read current state: get list of connected peers (ping them) let known_hosts = self.known_hosts.read().unwrap(); debug!("known_hosts: {} peers", known_hosts.list.len()); let mut to_ping = vec![]; let mut to_retry = vec![]; for (id, info) in known_hosts.list.iter() { debug!("{}, {:?}", hex::encode(id), info); match info.state { PeerConnState::Connected => { let must_ping = match info.last_seen { None => true, Some(t) => Instant::now() - t > PING_INTERVAL, }; if must_ping { to_ping.push(id.clone()); } } PeerConnState::Waiting(_, t) => { if Instant::now() >= t { to_retry.push(id.clone()); } } _ => (), } } drop(known_hosts); // 2. Dispatch ping to hosts trace!("to_ping: {} peers", to_retry.len()); for id in to_ping { tokio::spawn(self.clone().ping(id)); } // 3. Try reconnects trace!("to_retry: {} peers", to_retry.len()); if !to_retry.is_empty() { let mut known_hosts = self.known_hosts.write().unwrap(); for id in to_retry { if let Some(h) = known_hosts.list.get_mut(&id) { if let PeerConnState::Waiting(i, _) = h.state { info!( "Retrying connection to {} at {} ({})", hex::encode(&id), h.addr, i + 1 ); h.state = PeerConnState::Trying(i); tokio::spawn(self.clone().try_connect(id, h.addr.clone())); } } } } // 4. Sleep before next loop iteration tokio::time::delay_for(LOOP_DELAY).await; } } async fn ping(self: Arc, id: NodeID) { let peer_list_hash = self.known_hosts.read().unwrap().hash; let ping_id = self.next_ping_id.fetch_add(1u64, atomic::Ordering::Relaxed); let ping_time = Instant::now(); let ping_msg = PingMessage { id: ping_id, peer_list_hash, }; debug!( "Sending ping {} to {} at {:?}", ping_id, hex::encode(id), ping_time ); match self.netapp.request(&id, ping_msg, PRIO_HIGH).await { Err(e) => warn!("Error pinging {}: {}", hex::encode(id), e), Ok(ping_resp) => { let resp_time = Instant::now(); debug!( "Got ping response from {} at {:?}", hex::encode(id), resp_time ); { let mut known_hosts = self.known_hosts.write().unwrap(); if let Some(host) = known_hosts.list.get_mut(&id) { host.last_seen = Some(resp_time); host.ping.push_back(resp_time - ping_time); while host.ping.len() > 10 { host.ping.pop_front(); } } } if ping_resp.peer_list_hash != peer_list_hash { self.exchange_peers(&id).await; } } } } async fn exchange_peers(self: Arc, id: &NodeID) { let peer_list = KnownHosts::map_into_vec(&self.known_hosts.read().unwrap().list); let pex_message = PeerListMessage { list: peer_list }; match self.netapp.request(id, pex_message, PRIO_BACKGROUND).await { Err(e) => warn!("Error doing peer exchange: {}", e), Ok(resp) => { self.handle_peer_list(&resp.list[..]); } } } fn handle_peer_list(&self, list: &[(NodeID, SocketAddr)]) { let mut known_hosts = self.known_hosts.write().unwrap(); for (id, addr) in list.iter() { if !known_hosts.list.contains_key(id) { known_hosts.list.insert(*id, self.new_peer(id, *addr)); } } } async fn try_connect(self: Arc, id: NodeID, addr: SocketAddr) { let conn_result = self.netapp.clone().try_connect(addr, id.clone()).await; if let Err(e) = conn_result { warn!("Error connecting to {}: {}", hex::encode(id), e); let mut known_hosts = self.known_hosts.write().unwrap(); if let Some(host) = known_hosts.list.get_mut(&id) { host.state = match host.state { PeerConnState::Trying(i) => { if i >= CONN_MAX_RETRIES { PeerConnState::Abandonned } else { PeerConnState::Waiting(i + 1, Instant::now() + CONN_RETRY_INTERVAL) } } _ => PeerConnState::Waiting(0, Instant::now() + CONN_RETRY_INTERVAL), }; } } } async fn on_connected(self: Arc, id: NodeID, addr: SocketAddr, is_incoming: bool) { if is_incoming { if !self.known_hosts.read().unwrap().list.contains_key(&id) { self.known_hosts .write() .unwrap() .list .insert(id, self.new_peer(&id, addr)); } } else { info!("Successfully connected to {} at {}", hex::encode(&id), addr); let mut known_hosts = self.known_hosts.write().unwrap(); if let Some(host) = known_hosts.list.get_mut(&id) { host.state = PeerConnState::Connected; known_hosts.update_hash(); } } } async fn on_disconnected(self: Arc, id: NodeID, is_incoming: bool) { if !is_incoming { info!("Connection to {} was closed", hex::encode(id)); let mut known_hosts = self.known_hosts.write().unwrap(); if let Some(host) = known_hosts.list.get_mut(&id) { host.state = PeerConnState::Waiting(0, Instant::now()); known_hosts.update_hash(); } } } pub fn get_peer_list(&self) -> Vec { let known_hosts = self.known_hosts.read().unwrap(); let mut ret = Vec::with_capacity(known_hosts.list.len()); for (id, info) in known_hosts.list.iter() { let mut pings = info.ping.iter().cloned().collect::>(); pings.sort(); if pings.len() > 0 { ret.push(PeerInfoPub { id: id.clone(), addr: info.addr, state: info.state, last_seen: info.last_seen, avg_ping: Some( pings .iter() .fold(Duration::from_secs(0), |x, y| x + *y) .div_f64(pings.len() as f64), ), max_ping: pings.last().cloned(), med_ping: Some(pings[pings.len() / 2]), }); } else { ret.push(PeerInfoPub { id: id.clone(), addr: info.addr, state: info.state, last_seen: info.last_seen, avg_ping: None, max_ping: None, med_ping: None, }); } } ret } fn new_peer(&self, id: &NodeID, addr: SocketAddr) -> PeerInfo { let state = if *id == self.netapp.id { PeerConnState::Ourself } else { PeerConnState::Waiting(0, Instant::now()) }; PeerInfo { addr, state, last_seen: None, ping: VecDeque::new(), } } }