Implement get_block_roots for syncing

beacon_node/network/src/beacon_chain.rs

@@ -8,7 +8,7 @@ use beacon_chain::{
     CheckPoint,
 };
 use eth2_libp2p::HelloMessage;
-use types::{Epoch, Hash256, Slot};
+use types::{BeaconStateError, Epoch, Hash256, Slot};
 
 /// The network's API to the beacon chain.
 pub trait BeaconChain: Send + Sync {
@@ -29,6 +29,12 @@ pub trait BeaconChain: Send + Sync {
     fn finalized_epoch(&self) -> Epoch;
 
     fn hello_message(&self) -> HelloMessage;
+
+    fn get_block_roots(
+        &self,
+        start_slot: Slot,
+        count: Slot,
+    ) -> Result<Vec<Hash256>, BeaconStateError>;
 }
 
 impl<T, U, F> BeaconChain for RawBeaconChain<T, U, F>
@@ -81,4 +87,12 @@ where
             best_slot: self.best_slot(),
         }
     }
+
+    fn get_block_roots(
+        &self,
+        start_slot: Slot,
+        count: Slot,
+    ) -> Result<Vec<Hash256>, BeaconStateError> {
+        self.get_block_roots(start_slot, count)
+    }
 }

beacon_node/network/src/message_handler.rs

@@ -139,8 +139,19 @@ impl MessageHandler {
                 self.sync
                     .on_hello(peer_id, hello_message, &mut self.network_context);
             }
+            RPCResponse::BeaconBlockRoots(response) => {
+                debug!(
+                    self.log,
+                    "BeaconBlockRoots response received from peer: {:?}", peer_id
+                );
+                self.sync.on_beacon_block_roots_response(
+                    peer_id,
+                    response,
+                    &mut self.network_context,
+                )
+            }
             // TODO: Handle all responses
-            _ => {}
+            _ => panic!("Unknown response: {:?}", response),
         }
     }
 }

beacon_node/network/src/sync/simple_sync.rs

@@ -165,6 +165,15 @@ impl SimpleSync {
         }
     }
 
+    pub fn on_beacon_block_roots_response(
+        &mut self,
+        peer_id: PeerId,
+        reponse: BeaconBlockRootsResponse,
+        network: &mut NetworkContext,
+    ) {
+        //
+    }
+
     fn request_block_roots(
         &mut self,
         peer_id: PeerId,
@@ -174,9 +183,12 @@ impl SimpleSync {
     ) {
         // Potentially set state to sync.
         if self.state == SyncState::Idle && count > SLOT_IMPORT_TOLERANCE {
+            debug!(self.log, "Entering downloading sync state.");
             self.state = SyncState::Downloading;
         }
 
+        debug!(self.log, "Requesting {} blocks from {:?}.", count, &peer_id);
+
         // TODO: handle count > max count.
         network.send_rpc_request(
             peer_id.clone(),