Implement RequestBeaconBlockRoots RPC method

beacon_node/libp2p/src/rpc/methods.rs

@@ -6,6 +6,7 @@ use types::{Epoch, Hash256, Slot};
 pub enum RPCMethod {
     Hello,
     Goodbye,
+    RequestBeaconBlockRoots,
     Unknown,
 }
 
@@ -14,6 +15,7 @@ impl From<u16> for RPCMethod {
         match method_id {
             0 => RPCMethod::Hello,
             1 => RPCMethod::Goodbye,
+            10 => RPCMethod::RequestBeaconBlockRoots,
             _ => RPCMethod::Unknown,
         }
     }
@@ -24,6 +26,7 @@ impl Into<u16> for RPCMethod {
         match self {
             RPCMethod::Hello => 0,
             RPCMethod::Goodbye => 1,
+            RPCMethod::RequestBeaconBlockRoots => 10,
             _ => 0,
         }
     }
@@ -33,19 +36,53 @@ impl Into<u16> for RPCMethod {
 pub enum RPCRequest {
     Hello(HelloMessage),
     Goodbye(u64),
+    RequestBeaconBlockRoots(BeaconBlockRootsRequest),
 }
 
 #[derive(Debug, Clone)]
 pub enum RPCResponse {
     Hello(HelloMessage),
+    RequestBeaconBlockRoots(BeaconBlockRootsResponse),
 }
 
-// request/response structs for RPC methods
+/* Request/Response data structures for RPC methods */
+
+/// The HELLO request/response handshake message.
 #[derive(Encode, Decode, Clone, Debug)]
 pub struct HelloMessage {
+    /// The network ID of the peer.
     pub network_id: u8,
+    /// The peers last finalized root.
     pub latest_finalized_root: Hash256,
+    /// The peers last finalized epoch.
     pub latest_finalized_epoch: Epoch,
+    /// The peers last block root.
     pub best_root: Hash256,
+    /// The peers last slot.
     pub best_slot: Slot,
 }
+
+/// Request a number of beacon block roots from a peer.
+#[derive(Encode, Decode, Clone, Debug)]
+pub struct BeaconBlockRootsRequest {
+    /// The starting slot of the requested blocks.
+    start_slot: Slot,
+    /// The number of blocks from the start slot.
+    count: u64, // this must be less than 32768. //TODO: Enforce this in the lower layers
+}
+
+/// Response a number of beacon block roots from a peer.
+#[derive(Encode, Decode, Clone, Debug)]
+pub struct BeaconBlockRootsResponse {
+    /// List of requested blocks and associated slots.
+    roots: Vec<BlockRootSlot>,
+}
+
+/// Contains a block root and associated slot.
+#[derive(Encode, Decode, Clone, Debug)]
+pub struct BlockRootSlot {
+    /// The block root.
+    block_root: Hash256,
+    /// The block slot.
+    slot: Slot,
+}