feat(peer-store): introduce libp2p-peer-store

Introduce `libp2p-peer-store` for a peer store implementation.

Related: #4103

Pull-Request: #5724.

Cargo.toml

@@ -26,6 +26,7 @@ members = [
     "misc/memory-connection-limits",
     "misc/metrics",
     "misc/multistream-select",
+    "misc/peer-store",
     "misc/quick-protobuf-codec",
     "misc/quickcheck-ext",
     "misc/rw-stream-sink",
@@ -89,6 +90,7 @@ libp2p-memory-connection-limits = { version = "0.4.0", path = "misc/memory-conne
 libp2p-metrics = { version = "0.16.1", path = "misc/metrics" }
 libp2p-mplex = { version = "0.43.1", path = "muxers/mplex" }
 libp2p-noise = { version = "0.46.0", path = "transports/noise" }
+libp2p-peer-store = { version = "0.1.0", path = "misc/peer-store" }
 libp2p-perf = { version = "0.4.0", path = "protocols/perf" }
 libp2p-ping = { version = "0.46.0", path = "protocols/ping" }
 libp2p-plaintext = { version = "0.43.0", path = "transports/plaintext" }

libp2p/CHANGELOG.md

@@ -1,6 +1,9 @@
 ## 0.55.1
 - Introduce `libp2p-webrtc-websys` behind `webrtc-websys` feature flag.
   See [PR 5819](https://github.com/libp2p/rust-libp2p/pull/5819).
+
+- Introduce `libp2p-peer-store`.
+  See [PR 5724](https://github.com/libp2p/rust-libp2p/pull/5724).
 
 - Make the `*-websys` variants (`libp2p-webrtc-websys`, `libp2p-websocket-websys`, `libp2p-webtransport-websys`) only available on wasm32 target architecture.
   See [PR 5891](https://github.com/libp2p/rust-libp2p/pull/5891).

libp2p/Cargo.toml

@@ -29,6 +29,7 @@ full = [
     "memory-connection-limits",
     "metrics",
     "noise",
+    "peer-store",
     "ping",
     "plaintext",
     "pnet",
@@ -69,6 +70,7 @@ mdns = ["dep:libp2p-mdns"]
 memory-connection-limits = ["dep:libp2p-memory-connection-limits"]
 metrics = ["dep:libp2p-metrics"]
 noise = ["dep:libp2p-noise"]
+peer-store = ["dep:libp2p-peer-store"]
 ping = ["dep:libp2p-ping", "libp2p-metrics?/ping"]
 plaintext = ["dep:libp2p-plaintext"]
 pnet = ["dep:libp2p-pnet"]
@@ -111,6 +113,7 @@ libp2p-identity = { workspace = true, features = ["rand"] }
 libp2p-kad = { workspace = true, optional = true }
 libp2p-metrics = { workspace = true, optional = true }
 libp2p-noise = { workspace = true, optional = true }
+libp2p-peer-store = { workspace = true, optional = true }
 libp2p-ping = { workspace = true, optional = true }
 libp2p-plaintext = { workspace = true, optional = true }
 libp2p-pnet = { workspace = true, optional = true }

libp2p/src/lib.rs

@@ -81,6 +81,9 @@ pub use libp2p_metrics as metrics;
 #[cfg(feature = "noise")]
 #[doc(inline)]
 pub use libp2p_noise as noise;
+#[cfg(feature = "peer-store")]
+#[doc(inline)]
+pub use libp2p_peer_store as peer_store;
 #[cfg(feature = "ping")]
 #[doc(inline)]
 pub use libp2p_ping as ping;

misc/peer-store/CHANGELOG.md

@@ -0,0 +1,4 @@
+## 0.1.0
+
+- Introduce `libp2p-peer-store`.
+  See [PR 5724](https://github.com/libp2p/rust-libp2p/pull/5724).

misc/peer-store/Cargo.toml

@@ -0,0 +1,25 @@
+[package]
+name = "libp2p-peer-store"
+edition = "2021"
+version = "0.1.0"
+authors = ["drHuangMHT <[email protected]>"]
+license = "MIT"
+repository = "https://github.com/libp2p/rust-libp2p"
+publish = false
+rust-version.workspace = true
+
+[dependencies]
+libp2p-core = { workspace = true }
+libp2p-swarm = { workspace = true }
+lru = "0.12.3"
+libp2p-identity = { workspace = true, optional = true }
+
+[dev-dependencies]
+tokio = { workspace = true, features = ["macros", "rt-multi-thread"] }
+libp2p-identity = { workspace = true, features = ["rand", "serde"] }
+libp2p = { workspace = true, features = ["macros", "identify"] }
+libp2p-swarm-test = { path = "../../swarm-test", features = ["tokio"] }
+serde_json = { version = "1.0.134" }
+
+[lints]
+workspace = true

misc/peer-store/src/behaviour.rs

@@ -0,0 +1,161 @@
+use std::{collections::VecDeque, task::Poll};
+
+use libp2p_core::{Multiaddr, PeerId};
+use libp2p_swarm::{dummy, NetworkBehaviour};
+
+use crate::store::Store;
+
+/// Events generated by [`Behaviour`] and emitted back to [`Swarm`](libp2p_swarm::Swarm).
+#[derive(Debug, Clone)]
+pub enum Event<T> {
+    /// The peer's record has been updated.  
+    /// Manually updating a record will always emit this event
+    /// even if it provides no new information.
+    RecordUpdated {
+        /// The peer that has an update.
+        peer: PeerId,
+    },
+    /// Event from the internal store.
+    Store(T),
+}
+
+/// Behaviour that maintains a peer address book.
+///
+/// Usage:
+/// ```
+/// use libp2p::swarm::NetworkBehaviour;
+/// use libp2p_peer_store::{memory_store::MemoryStore, Behaviour};
+///
+/// // `identify::Behaviour` broadcasts listen addresses of the peer,
+/// // `peer_store::Behaviour` will then capture the resulting
+/// // `FromSwarm::NewExternalAddrOfPeer` and add the addresses
+/// // to address book.
+/// #[derive(NetworkBehaviour)]
+/// struct ComposedBehaviour {
+///     peer_store: Behaviour<MemoryStore>,
+///     identify: libp2p::identify::Behaviour,
+/// }
+/// ```
+pub struct Behaviour<S: Store> {
+    /// The internal store.
+    store: S,
+    /// Pending Events to be emitted back to [`Swarm`](libp2p_swarm::Swarm).
+    pending_events: VecDeque<Event<S::FromStore>>,
+}
+
+impl<'a, S> Behaviour<S>
+where
+    S: Store + 'static,
+{
+    /// Build a new [`Behaviour`] with the given store.
+    pub fn new(store: S) -> Self {
+        Self {
+            store,
+            pending_events: VecDeque::new(),
+        }
+    }
+
+    /// Try to get all observed address of the given peer.  
+    /// Returns `None` when the peer is not in the store.
+    pub fn address_of_peer<'b>(
+        &'a self,
+        peer: &'b PeerId,
+    ) -> Option<impl Iterator<Item = &'a Multiaddr> + use<'a, 'b, S>> {
+        self.store.addresses_of_peer(peer)
+    }
+
+    /// Get an immutable reference to the internal store.
+    pub fn store(&self) -> &S {
+        &self.store
+    }
+
+    /// Get a mutable reference to the internal store.
+    pub fn store_mut(&mut self) -> &mut S {
+        &mut self.store
+    }
+
+    fn handle_store_event(&mut self, event: crate::store::Event<<S as Store>::FromStore>) {
+        use crate::store::Event::*;
+        match event {
+            RecordUpdated(peer) => self.pending_events.push_back(Event::RecordUpdated { peer }),
+            Store(ev) => self.pending_events.push_back(Event::Store(ev)),
+        }
+    }
+}
+
+impl<S> NetworkBehaviour for Behaviour<S>
+where
+    S: Store + 'static,
+    <S as Store>::FromStore: Send + Sync,
+{
+    type ConnectionHandler = dummy::ConnectionHandler;
+
+    type ToSwarm = Event<S::FromStore>;
+
+    fn handle_established_inbound_connection(
+        &mut self,
+        _connection_id: libp2p_swarm::ConnectionId,
+        _peer: libp2p_core::PeerId,
+        _local_addr: &libp2p_core::Multiaddr,
+        _remote_addr: &libp2p_core::Multiaddr,
+    ) -> Result<libp2p_swarm::THandler<Self>, libp2p_swarm::ConnectionDenied> {
+        Ok(dummy::ConnectionHandler)
+    }
+
+    fn handle_pending_outbound_connection(
+        &mut self,
+        _connection_id: libp2p_swarm::ConnectionId,
+        maybe_peer: Option<PeerId>,
+        _addresses: &[Multiaddr],
+        _effective_role: libp2p_core::Endpoint,
+    ) -> Result<Vec<Multiaddr>, libp2p_swarm::ConnectionDenied> {
+        if maybe_peer.is_none() {
+            return Ok(Vec::new());
+        }
+        let peer = maybe_peer.expect("already handled");
+        Ok(self
+            .store
+            .addresses_of_peer(&peer)
+            .map(|i| i.cloned().collect())
+            .unwrap_or_default())
+    }
+
+    fn handle_established_outbound_connection(
+        &mut self,
+        _connection_id: libp2p_swarm::ConnectionId,
+        _peer: libp2p_core::PeerId,
+        _addr: &libp2p_core::Multiaddr,
+        _role_override: libp2p_core::Endpoint,
+        _port_use: libp2p_core::transport::PortUse,
+    ) -> Result<libp2p_swarm::THandler<Self>, libp2p_swarm::ConnectionDenied> {
+        Ok(dummy::ConnectionHandler)
+    }
+
+    fn on_swarm_event(&mut self, event: libp2p_swarm::FromSwarm) {
+        self.store.on_swarm_event(&event);
+    }
+
+    fn on_connection_handler_event(
+        &mut self,
+        _peer_id: libp2p_core::PeerId,
+        _connection_id: libp2p_swarm::ConnectionId,
+        _event: libp2p_swarm::THandlerOutEvent<Self>,
+    ) {
+        unreachable!("No event will be produced by a dummy handler.")
+    }
+
+    fn poll(
+        &mut self,
+        cx: &mut std::task::Context<'_>,
+    ) -> std::task::Poll<libp2p_swarm::ToSwarm<Self::ToSwarm, libp2p_swarm::THandlerInEvent<Self>>>
+    {
+        if let Some(ev) = self.store.poll(cx) {
+            self.handle_store_event(ev);
+        };
+
+        if let Some(ev) = self.pending_events.pop_front() {
+            return Poll::Ready(libp2p_swarm::ToSwarm::GenerateEvent(ev));
+        }
+        Poll::Pending
+    }
+}

misc/peer-store/src/lib.rs

@@ -0,0 +1,25 @@
+//! Implementation of peer store that stores address information
+//! about foreign peers.
+//!
+//! ## Important Discrepancies
+//! - **PeerStore is a local**: The peer store itself doesn't facilitate any information exchange
+//!   between peers. You will need other protocols like `libp2p-kad` to share addresses you know
+//!   across the network.
+//! - **PeerStore is a standalone**: Other protocols cannot expect the existence of PeerStore, and
+//!   need to be manually hooked up to PeerStore in order to obtain information it provides.
+//!
+//! ## Usage
+//! Compose [`Behaviour`] with other [`NetworkBehaviour`](libp2p_swarm::NetworkBehaviour),
+//! and the PeerStore will automatically track addresses from
+//! [`FromSwarm::NewExternalAddrOfPeer`](libp2p_swarm::FromSwarm)
+//! and provide addresses when dialing peers(require `extend_addresses_through_behaviour` in
+//! [`DialOpts`](libp2p_swarm::dial_opts::DialOpts) when dialing).  
+//! Other protocols need to be manually hooked up to obtain information from
+//! or provide information to PeerStore.
+
+mod behaviour;
+pub mod memory_store;
+mod store;
+
+pub use behaviour::{Behaviour, Event};
+pub use store::Store;