Default block announce validation should reject additional data (#7726)

If we are using the default block announce validator and receive
additional data alongside the block announcement, we should disconnect
this peer.

substrate/client/network/src/protocol.rs

@@ -1148,7 +1148,11 @@ impl<B: BlockT, H: ExHashT> Protocol<B, H> {
 				self.update_peer_info(&who);
 				(header, is_best, who)
 			}
-			sync::PollBlockAnnounceValidation::Failure { who } => {
+			sync::PollBlockAnnounceValidation::Failure { who, disconnect } => {
+				if disconnect {
+					self.disconnect_peer(&who);
+				}
+
 				self.report_peer(who, rep::BAD_BLOCK_ANNOUNCEMENT);
 				return CustomMessageOutcome::None
 			}

substrate/client/network/src/protocol/sync.rs

@@ -324,6 +324,8 @@ pub enum PollBlockAnnounceValidation<H> {
 	Failure {
 		/// Who sent the processed block announcement?
 		who: PeerId,
+		/// Should the peer be disconnected?
+		disconnect: bool,
 	},
 	/// The announcement does not require further handling.
 	Nothing {
@@ -354,6 +356,8 @@ enum PreValidateBlockAnnounce<H> {
 	Failure {
 		/// Who sent the processed block announcement?
 		who: PeerId,
+		/// Should the peer be disconnected?
+		disconnect: bool,
 	},
 	/// The announcement does not require further handling.
 	Nothing {
@@ -1215,14 +1219,14 @@ impl<B: BlockT> ChainSync<B> {
 					announce,
 					who,
 				},
-				Ok(Validation::Failure) => {
+				Ok(Validation::Failure { disconnect }) => {
 					debug!(
 						target: "sync",
 						"Block announcement validation of block {} from {} failed",
 						hash,
 						who,
 					);
-					PreValidateBlockAnnounce::Failure { who }
+					PreValidateBlockAnnounce::Failure { who, disconnect }
 				}
 				Err(e) => {
 					error!(target: "sync", "💔 Block announcement validation errored: {}", e);
@@ -1280,9 +1284,9 @@ impl<B: BlockT> ChainSync<B> {
 				self.peer_block_announce_validation_finished(&who);
 				return PollBlockAnnounceValidation::Nothing { is_best, who, header: announce.header }
 			},
-			PreValidateBlockAnnounce::Failure { who } => {
+			PreValidateBlockAnnounce::Failure { who, disconnect } => {
 				self.peer_block_announce_validation_finished(&who);
-				return PollBlockAnnounceValidation::Failure { who }
+				return PollBlockAnnounceValidation::Failure { who, disconnect }
 			},
 			PreValidateBlockAnnounce::Process { announce, is_new_best, who } => {
 				self.peer_block_announce_validation_finished(&who);

substrate/primitives/consensus/common/src/block_validation.rs

@@ -42,7 +42,12 @@ pub enum Validation {
 		is_new_best: bool,
 	},
 	/// Invalid block announcement.
-	Failure,
+	Failure {
+		/// Should we disconnect from this peer?
+		///
+		/// This should be used if the peer for example send junk to spam us.
+		disconnect: bool,
+	},
 }
 
 /// Type which checks incoming block announcements.
@@ -68,8 +73,20 @@ impl<B: Block> BlockAnnounceValidator<B> for DefaultBlockAnnounceValidator {
 	fn validate(
 		&mut self,
 		_: &B::Header,
-		_: &[u8],
+		data: &[u8],
 	) -> Pin<Box<dyn Future<Output = Result<Validation, Box<dyn Error + Send>>> + Send>> {
-		async { Ok(Validation::Success { is_new_best: false }) }.boxed()
+		let is_empty = data.is_empty();
+
+		async move {
+			if !is_empty {
+				log::debug!(
+					target: "sync",
+					"Received unknown data alongside the block announcement.",
+				);
+				Ok(Validation::Failure { disconnect: true })
+			} else {
+				Ok(Validation::Success { is_new_best: false })
+			}
+		}.boxed()
 	}
 }