Reject post fork gossip before fork

beacon_node/eth2_libp2p/src/behaviour/mod.rs

@@ -43,6 +43,7 @@ use std::{
     sync::Arc,
     task::{Context, Poll},
 };
+use types::ForkName;
 use types::{
     consts::altair::SYNC_COMMITTEE_SUBNET_COUNT, ChainSpec, EnrForkId, EthSpec, ForkContext,
     SignedBeaconBlock, Slot, SubnetId, SyncSubnetId,
@@ -103,6 +104,8 @@ pub enum BehaviourEvent<TSpec: EthSpec> {
         topic: TopicHash,
         /// The message itself.
         message: PubsubMessage<TSpec>,
+        /// The fork corresponding to the topic the message was received on.
+        fork_name: ForkName,
     },
     /// Inform the network to send a Status to this peer.
     StatusPeer(PeerId),
@@ -810,13 +813,14 @@ impl<TSpec: EthSpec> NetworkBehaviourEventProcess<GossipsubEvent> for Behaviour<
                             warn!(self.log, "Failed to report message validation"; "message_id" => %id, "peer_id" => %propagation_source, "error" => ?e);
                         }
                     }
-                    Ok(msg) => {
+                    Ok((msg, fork_name)) => {
                         // Notify the network
                         self.add_event(BehaviourEvent::PubsubMessage {
                             id,
                             source: propagation_source,
                             topic: gs_msg.topic,
                             message: msg,
+                            fork_name,
                         });
                     }
                 }

beacon_node/eth2_libp2p/src/types/pubsub.rs

@@ -117,90 +117,83 @@ impl<T: EthSpec> PubsubMessage<T> {
     }
 
     /// This decodes `data` into a `PubsubMessage` given a topic.
+    /// Returns the decoded data along with the fork name corresponding to the topic
+    /// the message was received on.
     /* Note: This is assuming we are not hashing topics. If we choose to hash topics, these will
      * need to be modified.
      */
     pub fn decode(
         topic: &TopicHash,
         data: &[u8],
         fork_context: &ForkContext,
-    ) -> Result<Self, String> {
+    ) -> Result<(Self, ForkName), String> {
         match GossipTopic::decode(topic.as_str()) {
             Err(_) => Err(format!("Unknown gossipsub topic: {:?}", topic)),
             Ok(gossip_topic) => {
+                let fork_name = fork_context
+                    .from_context_bytes(gossip_topic.fork_digest)
+                    .ok_or(format!(
+                        "Unknown gossipsub fork digest: {:?}",
+                        gossip_topic.fork_digest
+                    ))?;
+
                 // All topics are currently expected to be compressed and decompressed with snappy.
                 // This is done in the `SnappyTransform` struct.
                 // Therefore compression has already been handled for us by the time we are
                 // decoding the objects here.
 
                 // the ssz decoders
-                match gossip_topic.kind() {
+                let msg = match gossip_topic.kind() {
                     GossipKind::BeaconAggregateAndProof => {
                         let agg_and_proof = SignedAggregateAndProof::from_ssz_bytes(data)
                             .map_err(|e| format!("{:?}", e))?;
-                        Ok(PubsubMessage::AggregateAndProofAttestation(Box::new(
-                            agg_and_proof,
-                        )))
+                        PubsubMessage::AggregateAndProofAttestation(Box::new(agg_and_proof))
                     }
                     GossipKind::Attestation(subnet_id) => {
                         let attestation =
                             Attestation::from_ssz_bytes(data).map_err(|e| format!("{:?}", e))?;
-                        Ok(PubsubMessage::Attestation(Box::new((
-                            *subnet_id,
-                            attestation,
-                        ))))
+                        PubsubMessage::Attestation(Box::new((*subnet_id, attestation)))
                     }
                     GossipKind::BeaconBlock => {
-                        let beacon_block =
-                            match fork_context.from_context_bytes(gossip_topic.fork_digest) {
-                                Some(ForkName::Base) => SignedBeaconBlock::<T>::Base(
-                                    SignedBeaconBlockBase::from_ssz_bytes(data)
-                                        .map_err(|e| format!("{:?}", e))?,
-                                ),
-                                Some(ForkName::Altair) => SignedBeaconBlock::<T>::Altair(
-                                    SignedBeaconBlockAltair::from_ssz_bytes(data)
-                                        .map_err(|e| format!("{:?}", e))?,
-                                ),
-                                None => {
-                                    return Err(format!(
-                                        "Unknown gossipsub fork digest: {:?}",
-                                        gossip_topic.fork_digest
-                                    ))
-                                }
-                            };
-                        Ok(PubsubMessage::BeaconBlock(Box::new(beacon_block)))
+                        let beacon_block = match fork_name {
+                            ForkName::Base => SignedBeaconBlock::<T>::Base(
+                                SignedBeaconBlockBase::from_ssz_bytes(data)
+                                    .map_err(|e| format!("{:?}", e))?,
+                            ),
+                            ForkName::Altair => SignedBeaconBlock::<T>::Altair(
+                                SignedBeaconBlockAltair::from_ssz_bytes(data)
+                                    .map_err(|e| format!("{:?}", e))?,
+                            ),
+                        };
+                        PubsubMessage::BeaconBlock(Box::new(beacon_block))
                     }
                     GossipKind::VoluntaryExit => {
                         let voluntary_exit = SignedVoluntaryExit::from_ssz_bytes(data)
                             .map_err(|e| format!("{:?}", e))?;
-                        Ok(PubsubMessage::VoluntaryExit(Box::new(voluntary_exit)))
+                        PubsubMessage::VoluntaryExit(Box::new(voluntary_exit))
                     }
                     GossipKind::ProposerSlashing => {
                         let proposer_slashing = ProposerSlashing::from_ssz_bytes(data)
                             .map_err(|e| format!("{:?}", e))?;
-                        Ok(PubsubMessage::ProposerSlashing(Box::new(proposer_slashing)))
+                        PubsubMessage::ProposerSlashing(Box::new(proposer_slashing))
                     }
                     GossipKind::AttesterSlashing => {
                         let attester_slashing = AttesterSlashing::from_ssz_bytes(data)
                             .map_err(|e| format!("{:?}", e))?;
-                        Ok(PubsubMessage::AttesterSlashing(Box::new(attester_slashing)))
+                        PubsubMessage::AttesterSlashing(Box::new(attester_slashing))
                     }
                     GossipKind::SignedContributionAndProof => {
                         let sync_aggregate = SignedContributionAndProof::from_ssz_bytes(data)
                             .map_err(|e| format!("{:?}", e))?;
-                        Ok(PubsubMessage::SignedContributionAndProof(Box::new(
-                            sync_aggregate,
-                        )))
+                        PubsubMessage::SignedContributionAndProof(Box::new(sync_aggregate))
                     }
                     GossipKind::SyncCommitteeMessage(subnet_id) => {
                         let sync_committee = SyncCommitteeMessage::from_ssz_bytes(data)
                             .map_err(|e| format!("{:?}", e))?;
-                        Ok(PubsubMessage::SyncCommitteeMessage(Box::new((
-                            *subnet_id,
-                            sync_committee,
-                        ))))
+                        PubsubMessage::SyncCommitteeMessage(Box::new((*subnet_id, sync_committee)))
                     }
-                }
+                };
+                Ok((msg, *fork_name))
             }
         }
     }

beacon_node/network/src/service.rs

@@ -190,6 +190,8 @@ impl<T: BeaconChainTypes> NetworkService<T> {
             &beacon_chain.spec,
         ));
 
+        debug!(network_log, "Current fork"; "fork_name" => ?fork_context.current_fork());
+
         // launch libp2p service
         let (network_globals, mut libp2p) = LibP2PService::new(
             executor.clone(),
@@ -600,10 +602,36 @@ fn spawn_service<T: BeaconChainTypes>(
                                 id,
                                 source,
                                 message,
-                                ..
+                                fork_name,
+                                topic,
                             } => {
                                 // Update prometheus metrics.
                                 metrics::expose_receive_metrics(&message);
+
+                                if fork_name != service.fork_context.current_fork() {
+                                    if let Some((_, next_fork_duration)) = service.beacon_chain.duration_to_next_fork() {
+                                        // This implies that the peer is sending messages on post fork topics
+                                        // before the fork. We ignore the message and score down the peer.
+                                        if next_fork_duration > beacon_chain::MAXIMUM_GOSSIP_CLOCK_DISPARITY {
+                                            debug!(
+                                                service.log,
+                                                "Peer sent gossip on incorrect fork version topic";
+                                                "peer" => %source,
+                                                "fork_topic" => %topic,
+                                            );
+                                            service.libp2p.report_peer(&source, PeerAction::LowToleranceError, ReportSource::Gossipsub);
+                                            service
+                                                .libp2p
+                                                .swarm
+                                                .behaviour_mut()
+                                                .report_message_validation_result(
+                                                    &source, id, MessageAcceptance::Ignore,
+                                                );
+                                            continue;
+                                        }
+                                    }
+
+                                }
                                 match message {
                                     // attestation information gets processed in the attestation service
                                     PubsubMessage::Attestation(ref subnet_and_attestation) => {