feat: status req res (#492)

lib/lambda_ethereum_consensus/fork_choice/helpers.ex

@@ -8,6 +8,23 @@ defmodule LambdaEthereumConsensus.ForkChoice.Helpers do
   alias SszTypes.Checkpoint
   alias SszTypes.Store
 
+  @spec current_status_message(Store.t()) ::
+          {:ok, SszTypes.StatusMessage.t()} | {:error, any}
+  def current_status_message(store) do
+    with {:ok, head_root} <- get_head(store),
+         {:ok, state} <- Map.fetch(store.block_states, head_root) do
+      {:ok,
+       %SszTypes.StatusMessage{
+         fork_digest:
+           Misc.compute_fork_digest(state.fork.current_version, state.genesis_validators_root),
+         finalized_root: state.finalized_checkpoint.root,
+         finalized_epoch: state.finalized_checkpoint.epoch,
+         head_root: head_root,
+         head_slot: state.slot
+       }}
+    end
+  end
+
   @spec get_forkchoice_store(BeaconState.t(), BeaconBlock.t()) :: {:ok, Store.t()} | {:error, any}
   def get_forkchoice_store(%BeaconState{} = anchor_state, %BeaconBlock{} = anchor_block) do
     anchor_state_root = Ssz.hash_tree_root!(anchor_state)

lib/lambda_ethereum_consensus/fork_choice/store.ex

@@ -36,6 +36,11 @@ defmodule LambdaEthereumConsensus.ForkChoice.Store do
     div(time - genesis_time, ChainSpec.get("SECONDS_PER_SLOT"))
   end
 
+  @spec get_current_status_message() :: {:ok, SszTypes.StatusMessage.t()} | {:error, any}
+  def get_current_status_message do
+    GenServer.call(__MODULE__, :get_current_status_message, @default_timeout)
+  end
+
   @spec has_block?(SszTypes.root()) :: boolean()
   def has_block?(block_root) do
     block = get_block(block_root)
@@ -89,6 +94,11 @@ defmodule LambdaEthereumConsensus.ForkChoice.Store do
     {:reply, values, state}
   end
 
+  @impl GenServer
+  def handle_call(:get_current_status_message, _from, state) do
+    {:reply, Helpers.current_status_message(state)}
+  end
+
   def handle_call({:get_block, block_root}, _from, state) do
     {:reply, Map.get(state.blocks, block_root), state}
   end

lib/lambda_ethereum_consensus/p2p/incoming_requests/handler.ex

@@ -2,9 +2,11 @@ defmodule LambdaEthereumConsensus.P2P.IncomingRequests.Handler do
   @moduledoc """
   This module handles Req/Resp domain requests.
   """
-  require Logger
-  alias LambdaEthereumConsensus.{Libp2pPort, P2P}
+
+  alias LambdaEthereumConsensus.ForkChoice
   alias LambdaEthereumConsensus.Store.BlockStore
+  alias LambdaEthereumConsensus.{Libp2pPort, P2P}
+  require Logger
 
   # This is the `ForkDigest` for mainnet in the capella fork
   # TODO: compute this at runtime
@@ -28,18 +30,8 @@ defmodule LambdaEthereumConsensus.P2P.IncomingRequests.Handler do
   @spec handle_req(String.t(), String.t(), binary()) ::
           :ok | :not_implemented | {:error, binary()}
   defp handle_req("status/1/ssz_snappy", message_id, message) do
-    # hardcoded response from random peer
-    current_status = %SszTypes.StatusMessage{
-      fork_digest: Base.decode16!("BBA4DA96"),
-      finalized_root:
-        Base.decode16!("7715794499C07D9954DD223EC2C6B846D3BAB27956D093000FADC1B8219F74D4"),
-      finalized_epoch: 228_168,
-      head_root:
-        Base.decode16!("D62A74AE0F933224133C5E6E1827A2835A1E705F0CDFEE3AD25808DDEA5572DB"),
-      head_slot: 7_301_450
-    }
-
     with <<84, snappy_status::binary>> <- message,
+         {:ok, current_status} <- ForkChoice.Store.get_current_status_message(),
          {:ok, ssz_status} <- Snappy.decompress(snappy_status),
          {:ok, status} <- Ssz.from_ssz(ssz_status, SszTypes.StatusMessage),
          status