feat(net): add NetworkMode to enforce POS rules (#215)

crates/net/network/src/config.rs

@@ -1,5 +1,5 @@
 use crate::{
-    import::{BlockImport, NoopBlockImport},
+    import::{BlockImport, ProofOfStakeBlockImport},
     peers::PeersConfig,
     session::SessionsConfig,
 };
@@ -36,6 +36,8 @@ pub struct NetworkConfig<C> {
     pub genesis_hash: H256,
     /// The block importer type.
     pub block_import: Box<dyn BlockImport>,
+    /// The default mode of the network.
+    pub network_mode: NetworkMode,
 }
 
 // === impl NetworkConfig ===
@@ -90,6 +92,8 @@ pub struct NetworkConfigBuilder<C> {
     genesis_hash: H256,
     /// The block importer type.
     block_import: Box<dyn BlockImport>,
+    /// The default mode of the network.
+    network_mode: NetworkMode,
 }
 
 // === impl NetworkConfigBuilder ===
@@ -108,7 +112,8 @@ impl<C> NetworkConfigBuilder<C> {
             fork_id: None,
             chain: Chain::Named(reth_primitives::rpc::Chain::Mainnet),
             genesis_hash: Default::default(),
-            block_import: Box::<NoopBlockImport>::default(),
+            block_import: Box::<ProofOfStakeBlockImport>::default(),
+            network_mode: Default::default(),
         }
     }
 
@@ -138,6 +143,7 @@ impl<C> NetworkConfigBuilder<C> {
             chain,
             genesis_hash,
             block_import,
+            network_mode,
         } = self;
         NetworkConfig {
             client,
@@ -155,6 +161,30 @@ impl<C> NetworkConfigBuilder<C> {
             chain,
             genesis_hash,
             block_import,
+            network_mode,
         }
     }
 }
+
+/// Describes the mode of the network wrt. POS or POW.
+///
+/// This affects block propagation in the `eth` sub-protocol [EIP-3675](https://eips.ethereum.org/EIPS/eip-3675#devp2p)
+///
+/// In POS `NewBlockHashes` and `NewBlock` messages become invalid.
+#[derive(Debug, Clone, Copy, Eq, PartialEq, Default)]
+pub enum NetworkMode {
+    /// Network is in proof-of-work mode.
+    Work,
+    /// Network is in proof-of-stake mode
+    #[default]
+    Stake,
+}
+
+// === impl NetworkMode ===
+
+impl NetworkMode {
+    /// Returns true if network has entered proof-of-stake
+    pub fn is_stake(&self) -> bool {
+        matches!(self, NetworkMode::Stake)
+    }
+}

crates/net/network/src/import.rs

@@ -50,12 +50,14 @@ pub enum BlockImportError {
     Consensus(#[from] reth_interfaces::consensus::Error),
 }
 
-/// An implementation of `BlockImport` that does nothing
+/// An implementation of `BlockImport` used in Proof-of-Stake consensus that does nothing.
+///
+/// Block propagation over devp2p is invalid in POS: [EIP-3675](https://eips.ethereum.org/EIPS/eip-3675#devp2p)
 #[derive(Debug, Default)]
 #[non_exhaustive]
-pub struct NoopBlockImport;
+pub struct ProofOfStakeBlockImport;
 
-impl BlockImport for NoopBlockImport {
+impl BlockImport for ProofOfStakeBlockImport {
     fn on_new_block(&mut self, _peer_id: PeerId, _incoming_block: NewBlockMessage) {}
 
     fn poll(&mut self, _cx: &mut Context<'_>) -> Poll<BlockImportOutcome> {

crates/net/network/src/manager.rs

@@ -115,6 +115,7 @@ where
             sessions_config,
             genesis_hash,
             block_import,
+            network_mode,
             ..
         } = config;
 
@@ -142,6 +143,7 @@ where
             to_manager_tx,
             local_node_id,
             peers_handle,
+            network_mode,
         );
 
         Ok(Self {
@@ -211,18 +213,40 @@ where
         }
     }
 
+    /// Enforces [EIP-3675](https://eips.ethereum.org/EIPS/eip-3675#devp2p) consensus rules for the network protocol
+    ///
+    /// Depending on the mode of the network:
+    ///    - disconnect peer if in POS
+    ///    - execute the closure if in POW
+    fn within_pow_or_disconnect<F>(&mut self, peer_id: PeerId, only_pow: F)
+    where
+        F: FnOnce(&mut Self),
+    {
+        // reject message in POS
+        if self.handle.mode().is_stake() {
+            // connections to peers which send invalid messages should be terminated
+            self.swarm.sessions_mut().disconnect(peer_id);
+        } else {
+            only_pow(self);
+        }
+    }
+
     /// Handles a received Message from the peer.
     fn on_peer_message(&mut self, peer_id: PeerId, msg: PeerMessage) {
         match msg {
             PeerMessage::NewBlockHashes(hashes) => {
-                let hashes = Arc::try_unwrap(hashes).unwrap_or_else(|arc| (*arc).clone());
-                // update peer's state, to track what blocks this peer has seen
-                self.swarm.state_mut().on_new_block_hashes(peer_id, hashes.0)
+                self.within_pow_or_disconnect(peer_id, |this| {
+                    let hashes = Arc::try_unwrap(hashes).unwrap_or_else(|arc| (*arc).clone());
+                    // update peer's state, to track what blocks this peer has seen
+                    this.swarm.state_mut().on_new_block_hashes(peer_id, hashes.0)
+                })
             }
             PeerMessage::NewBlock(block) => {
-                self.swarm.state_mut().on_new_block(peer_id, block.hash);
-                // start block import process
-                self.block_import.on_new_block(peer_id, block);
+                self.within_pow_or_disconnect(peer_id, move |this| {
+                    this.swarm.state_mut().on_new_block(peer_id, block.hash);
+                    // start block import process
+                    this.block_import.on_new_block(peer_id, block);
+                });
             }
             PeerMessage::PooledTransactions(msg) => {
                 self.event_listeners
@@ -245,6 +269,10 @@ where
                 self.event_listeners.listeners.push(tx);
             }
             NetworkHandleMessage::AnnounceBlock(block, hash) => {
+                if self.handle.mode().is_stake() {
+                    error!(target = "net", "Block propagation is not supported in POS - [EIP-3675](https://eips.ethereum.org/EIPS/eip-3675#devp2p)");
+                    return
+                }
                 let msg = NewBlockMessage { hash, block: Arc::new(block) };
                 self.swarm.state_mut().announce_new_block(msg);
             }

crates/net/network/src/network.rs

@@ -1,4 +1,4 @@
-use crate::{manager::NetworkEvent, message::PeerRequest, peers::PeersHandle};
+use crate::{config::NetworkMode, manager::NetworkEvent, message::PeerRequest, peers::PeersHandle};
 use parking_lot::Mutex;
 use reth_eth_wire::{NewBlock, NewPooledTransactionHashes, Transactions};
 use reth_primitives::{PeerId, H256};
@@ -27,6 +27,7 @@ impl NetworkHandle {
         to_manager_tx: UnboundedSender<NetworkHandleMessage>,
         local_node_id: PeerId,
         peers: PeersHandle,
+        network_mode: NetworkMode,
     ) -> Self {
         let inner = NetworkInner {
             num_active_peers,
@@ -34,6 +35,7 @@ impl NetworkHandle {
             listener_address,
             local_node_id,
             peers,
+            network_mode,
         };
         Self { inner: Arc::new(inner) }
     }
@@ -49,6 +51,11 @@ impl NetworkHandle {
         rx
     }
 
+    /// Returns the mode of the network, either pow, or pos
+    pub fn mode(&self) -> &NetworkMode {
+        &self.inner.network_mode
+    }
+
     /// Sends a [`NetworkHandleMessage`] to the manager
     pub(crate) fn send_message(&self, msg: NetworkHandleMessage) {
         let _ = self.inner.to_manager_tx.send(msg);
@@ -71,6 +78,8 @@ struct NetworkInner {
     local_node_id: PeerId,
     /// Access to the all the nodes
     peers: PeersHandle,
+    /// The mode of the network
+    network_mode: NetworkMode,
 }
 
 /// Internal messages that can be passed to the  [`NetworkManager`](crate::NetworkManager).