Remove unused light-client leftover (#13687)

* Remove unused light-client leftover

* Remove more unused code

client/network/sync/src/engine.rs

@@ -58,10 +58,7 @@ use sc_network_common::{
 use sc_utils::mpsc::{tracing_unbounded, TracingUnboundedReceiver, TracingUnboundedSender};
 use sp_blockchain::HeaderMetadata;
 use sp_consensus::block_validation::BlockAnnounceValidator;
-use sp_runtime::{
-	traits::{Block as BlockT, CheckedSub, Header, NumberFor, Zero},
-	SaturatedConversion,
-};
+use sp_runtime::traits::{Block as BlockT, Header, NumberFor, Zero};
 
 use std::{
 	collections::{HashMap, HashSet},
@@ -77,24 +74,15 @@ use std::{
 /// Interval at which we perform time based maintenance
 const TICK_TIMEOUT: std::time::Duration = std::time::Duration::from_millis(1100);
 
-/// When light node connects to the full node and the full node is behind light node
-/// for at least `LIGHT_MAXIMAL_BLOCKS_DIFFERENCE` blocks, we consider it not useful
-/// and disconnect to free connection slot.
-const LIGHT_MAXIMAL_BLOCKS_DIFFERENCE: u64 = 8192;
-
 /// Maximum number of known block hashes to keep for a peer.
 const MAX_KNOWN_BLOCKS: usize = 1024; // ~32kb per peer + LruHashSet overhead
 
 mod rep {
 	use sc_peerset::ReputationChange as Rep;
-	/// Reputation change when we are a light client and a peer is behind us.
-	pub const PEER_BEHIND_US_LIGHT: Rep = Rep::new(-(1 << 8), "Useless for a light peer");
 	/// We received a message that failed to decode.
 	pub const BAD_MESSAGE: Rep = Rep::new(-(1 << 12), "Bad message");
 	/// Peer has different genesis.
 	pub const GENESIS_MISMATCH: Rep = Rep::new_fatal("Genesis mismatch");
-	/// Peer role does not match (e.g. light peer connecting to another light peer).
-	pub const BAD_ROLE: Rep = Rep::new_fatal("Unsupported role");
 	/// Peer send us a block announcement that failed at validation.
 	pub const BAD_BLOCK_ANNOUNCEMENT: Rep = Rep::new(-(1 << 12), "Bad block announcement");
 }
@@ -834,31 +822,6 @@ where
 			return Err(())
 		}
 
-		if self.roles.is_light() {
-			// we're not interested in light peers
-			if status.roles.is_light() {
-				log::debug!(target: "sync", "Peer {} is unable to serve light requests", who);
-				self.network_service.report_peer(who, rep::BAD_ROLE);
-				self.network_service
-					.disconnect_peer(who, self.block_announce_protocol_name.clone());
-				return Err(())
-			}
-
-			// we don't interested in peers that are far behind us
-			let self_best_block = self.client.info().best_number;
-			let blocks_difference = self_best_block
-				.checked_sub(&status.best_number)
-				.unwrap_or_else(Zero::zero)
-				.saturated_into::<u64>();
-			if blocks_difference > LIGHT_MAXIMAL_BLOCKS_DIFFERENCE {
-				log::debug!(target: "sync", "Peer {} is far behind us and will unable to serve light requests", who);
-				self.network_service.report_peer(who, rep::PEER_BEHIND_US_LIGHT);
-				self.network_service
-					.disconnect_peer(who, self.block_announce_protocol_name.clone());
-				return Err(())
-			}
-		}
-
 		let no_slot_peer = self.default_peers_set_no_slot_peers.contains(&who);
 		let this_peer_reserved_slot: usize = if no_slot_peer { 1 } else { 0 };