Implement BeaconBlockHeaders RPC method

beacon_node/libp2p/src/rpc/methods.rs

@@ -1,12 +1,13 @@
 /// Available RPC methods types and ids.
 use ssz_derive::{Decode, Encode};
-use types::{Epoch, Hash256, Slot};
+use types::{BeaconBlockHeader, Epoch, Hash256, Slot};
 
 #[derive(Debug)]
 pub enum RPCMethod {
     Hello,
     Goodbye,
     BeaconBlockRoots,
+    BeaconBlockHeaders,
     Unknown,
 }
 
@@ -16,6 +17,7 @@ impl From<u16> for RPCMethod {
             0 => RPCMethod::Hello,
             1 => RPCMethod::Goodbye,
             10 => RPCMethod::BeaconBlockRoots,
+            11 => RPCMethod::BeaconBlockHeaders,
             _ => RPCMethod::Unknown,
         }
     }
@@ -27,6 +29,7 @@ impl Into<u16> for RPCMethod {
             RPCMethod::Hello => 0,
             RPCMethod::Goodbye => 1,
             RPCMethod::BeaconBlockRoots => 10,
+            RPCMethod::BeaconBlockHeaders => 11,
             _ => 0,
         }
     }
@@ -37,12 +40,14 @@ pub enum RPCRequest {
     Hello(HelloMessage),
     Goodbye(u64),
     BeaconBlockRoots(BeaconBlockRootsRequest),
+    BeaconBlockHeaders(BeaconBlockHeadersRequest),
 }
 
 #[derive(Debug, Clone)]
 pub enum RPCResponse {
     Hello(HelloMessage),
     BeaconBlockRoots(BeaconBlockRootsResponse),
+    BeaconBlockHeaders(BeaconBlockHeadersResponse),
 }
 
 /* Request/Response data structures for RPC methods */
@@ -71,7 +76,7 @@ pub struct BeaconBlockRootsRequest {
     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.
+/// Response containing a number of beacon block roots from a peer.
 #[derive(Encode, Decode, Clone, Debug)]
 pub struct BeaconBlockRootsResponse {
     /// List of requested blocks and associated slots.
@@ -86,3 +91,23 @@ pub struct BlockRootSlot {
     /// The block slot.
     slot: Slot,
 }
+
+/// Request a number of beacon block headers from a peer.
+#[derive(Encode, Decode, Clone, Debug)]
+pub struct BeaconBlockHeadersRequest {
+    /// The starting header hash of the requested headers.
+    start_root: Hash256,
+    /// The starting slot of the requested headers.
+    start_slot: Slot,
+    /// The maximum number of headers than can be returned.
+    max_headers: u64,
+    /// The maximum number of slots to skip between blocks.
+    skip_slots: u64,
+}
+
+/// Response containing requested block headers.
+#[derive(Encode, Decode, Clone, Debug)]
+pub struct BeaconBlockHeadersResponse {
+    /// The list of requested beacon block headers.
+    headers: Vec<BeaconBlockHeader>,
+}