Sync corrections (#1034)

* Correct status re-request logic improve logging

* Prevent multiple dials of the same peer

* Discovery to obey max peers when connecting to new peers

beacon_node/network/src/router/mod.rs

@@ -8,7 +8,7 @@ pub mod processor;
 
 use crate::error;
 use crate::service::NetworkMessage;
-use beacon_chain::{AttestationType, BeaconChain, BeaconChainTypes};
+use beacon_chain::{AttestationType, BeaconChain, BeaconChainTypes, BlockError};
 use eth2_libp2p::{
     rpc::{RPCError, RPCErrorResponse, RPCRequest, RPCResponse, RequestId, ResponseTermination},
     MessageId, NetworkGlobals, PeerId, PubsubMessage, RPCEvent,
@@ -268,7 +268,9 @@ impl<T: BeaconChainTypes> Router<T> {
                         self.propagate_message(id, peer_id.clone());
                         self.processor.on_block_gossip(peer_id, verified_block);
                     }
+                    Err(BlockError::ParentUnknown { .. }) => {} // performing a parent lookup
                     Err(e) => {
+                        // performing a parent lookup
                         warn!(self.log, "Could not verify block for gossip";
                             "error" => format!("{:?}", e));
                     }

beacon_node/network/src/router/processor.rs

@@ -495,9 +495,10 @@ impl<T: BeaconChainTypes> Processor<T> {
     ) -> Result<GossipVerifiedBlock<T>, BlockError> {
         let result = self.chain.verify_block_for_gossip(*block.clone());
 
-        if let Err(BlockError::ParentUnknown(_)) = result {
+        if let Err(BlockError::ParentUnknown(block_hash)) = result {
             // if we don't know the parent, start a parent lookup
             // TODO: Modify the return to avoid the block clone.
+            debug!(self.log, "Unknown block received. Starting a parent lookup"; "block_slot" => block.message.slot, "block_hash" => format!("{}", block_hash));
             self.send_to_sync(SyncMessage::UnknownBlock(peer_id.clone(), block));
         }
         result