feat: ping metadata

lib/lambda_ethereum_consensus/application.ex

@@ -34,6 +34,8 @@ defmodule LambdaEthereumConsensus.Application do
       {LambdaEthereumConsensus.Beacon.PendingBlocks, []},
       {LambdaEthereumConsensus.Beacon.SyncBlocks, []},
       {LambdaEthereumConsensus.P2P.GossipSub, []},
+      {LambdaEthereumConsensus.P2P.Metadata, []},
+      # Start the Endpoint (http/https)
       {BeaconApi.Endpoint, []}
     ]
 

lib/lambda_ethereum_consensus/p2p/incoming_requests/handler.ex

@@ -2,11 +2,11 @@ defmodule LambdaEthereumConsensus.P2P.IncomingRequests.Handler do
   @moduledoc """
   This module handles Req/Resp domain requests.
   """
+  require Logger
 
   alias LambdaEthereumConsensus.ForkChoice
-  alias LambdaEthereumConsensus.Store.BlockStore
   alias LambdaEthereumConsensus.{Libp2pPort, P2P}
-  require Logger
+  alias LambdaEthereumConsensus.Store.BlockStore
 
   # This is the `ForkDigest` for mainnet in the capella fork
   # TODO: compute this at runtime
@@ -85,9 +85,8 @@ defmodule LambdaEthereumConsensus.P2P.IncomingRequests.Handler do
 
   defp handle_req("metadata/2/ssz_snappy", message_id, _message) do
     # Values are hardcoded
-    with {:ok, payload} <-
-           <<0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0>>
-           |> Snappy.compress() do
+    with metadata <- P2P.Metadata.get_metadata(),
+         {:ok, payload} <- Ssz.to_ssz(metadata) |> Snappy.compress() do
       Libp2pPort.send_response(message_id, <<0, 17>> <> payload)
     end
   end

lib/lambda_ethereum_consensus/p2p/metadata.ex

@@ -0,0 +1,58 @@
+defmodule LambdaEthereumConsensus.P2P.Metadata do
+  @moduledoc """
+  This module handles Metadata's genserver to fetch and edit.
+  """
+
+  use GenServer
+  use Supervisor
+
+  alias SszTypes.Metadata
+
+  ##########################
+  ### Public API
+  ##########################
+
+  def start_link(arg) do
+    Supervisor.start_link(__MODULE__, arg, name: __MODULE__)
+  end
+
+  @spec get_seq_number() :: SszTypes.uint64()
+  def get_seq_number do
+    [seq_number] = get_metadata_attrs([:seq_number])
+    seq_number
+  end
+
+  @spec get_metadata() :: Metadata.t()
+  def get_metadata do
+    GenServer.call(__MODULE__, :get_metadata)
+  end
+
+  ##########################
+  ### GenServer Callbacks
+  ##########################
+
+  @impl GenServer
+  def init(metadata) do
+    {:ok, metadata}
+  end
+
+  @impl GenServer
+  def handle_call({:get_metadata_attrs, attrs}, _from, metadata) do
+    values = Enum.map(attrs, &Map.fetch!(metadata, &1))
+    {:reply, values, metadata}
+  end
+
+  @impl GenServer
+  def handle_call(:get_metadata, _from, metadata) do
+    {:reply, metadata}
+  end
+
+  ##########################
+  ### Private Functions
+  ##########################
+
+  @spec get_metadata_attrs([atom()]) :: [any()]
+  defp get_metadata_attrs(attrs) do
+    GenServer.call(__MODULE__, {:get_metadata_attrs, attrs})
+  end
+end