From 18f2c6aa57f5ea5ef01be90b34b493bf6994200a Mon Sep 17 00:00:00 2001
From: gabrielbosio <gabrielbosio95@gmail.com>
Date: Thu, 19 May 2022 19:12:04 -0300
Subject: [PATCH 01/13] Add DNS data retrieval

Add elixir-dns dependency.
The function returns the data as it is, we still need to make the function
return the URL that geth will use. I suppose that we can make that URL using the
data that the DNS returns.
---
 eth_client/lib/eth_client/nodes_list.ex | 22 ++++++++++++++++++++++
 eth_client/mix.exs                      |  3 ++-
 eth_client/mix.lock                     |  2 ++
 3 files changed, 26 insertions(+), 1 deletion(-)
 create mode 100644 eth_client/lib/eth_client/nodes_list.ex

diff --git a/eth_client/lib/eth_client/nodes_list.ex b/eth_client/lib/eth_client/nodes_list.ex
new file mode 100644
index 0000000..ac56774
--- /dev/null
+++ b/eth_client/lib/eth_client/nodes_list.ex
@@ -0,0 +1,22 @@
+defmodule EthClient.NodesList do
+  alias DNS.Record
+  alias DNS.Resource
+
+  @type network :: :mainnet | :ropsten | :rinkeby | :goerli
+
+  @spec get_by_dns(network()) :: Record.t()
+  def get_by_dns(network) do
+    %Record{anlist: [%Resource{data: [enrtree_data]}]} =
+      network
+      |> get_domain_name()
+      |> DNS.query(:txt)
+
+    enrtree_data
+  end
+
+  @spec get_domain_name(network()) :: String.t()
+  defp get_domain_name(:mainnet), do: "all.mainnet.ethdisco.net"
+  defp get_domain_name(:ropsten), do: "all.ropsten.ethdisco.net"
+  defp get_domain_name(:rinkeby), do: "all.rinkeby.ethdisco.net"
+  defp get_domain_name(:goerli), do: "all.goerli.ethdisco.net"
+end
diff --git a/eth_client/mix.exs b/eth_client/mix.exs
index f460b7c..ebfd861 100644
--- a/eth_client/mix.exs
+++ b/eth_client/mix.exs
@@ -31,7 +31,8 @@ defmodule EthClient.MixProject do
       {:rustler, "~> 0.25.0"},
       {:ex_rlp, "~> 0.5.4"},
       {:dialyxir, "~> 1.1", only: [:dev, :test], runtime: false},
-      {:excoveralls, "~> 0.14.5", only: [:test], runtime: false}
+      {:excoveralls, "~> 0.14.5", only: [:test], runtime: false},
+      {:dns, "~> 2.3.0"}
     ]
   end
 end
diff --git a/eth_client/mix.lock b/eth_client/mix.lock
index 8a1256f..67348ab 100644
--- a/eth_client/mix.lock
+++ b/eth_client/mix.lock
@@ -3,6 +3,7 @@
   "certifi": {:hex, :certifi, "2.9.0", "6f2a475689dd47f19fb74334859d460a2dc4e3252a3324bd2111b8f0429e7e21", [:rebar3], [], "hexpm", "266da46bdb06d6c6d35fde799bcb28d36d985d424ad7c08b5bb48f5b5cdd4641"},
   "credo": {:hex, :credo, "1.6.4", "ddd474afb6e8c240313f3a7b0d025cc3213f0d171879429bf8535d7021d9ad78", [:mix], [{:bunt, "~> 0.2.0", [hex: :bunt, repo: "hexpm", optional: false]}, {:file_system, "~> 0.2.8", [hex: :file_system, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: false]}], "hexpm", "c28f910b61e1ff829bffa056ef7293a8db50e87f2c57a9b5c3f57eee124536b7"},
   "dialyxir": {:hex, :dialyxir, "1.1.0", "c5aab0d6e71e5522e77beff7ba9e08f8e02bad90dfbeffae60eaf0cb47e29488", [:mix], [{:erlex, ">= 0.2.6", [hex: :erlex, repo: "hexpm", optional: false]}], "hexpm", "07ea8e49c45f15264ebe6d5b93799d4dd56a44036cf42d0ad9c960bc266c0b9a"},
+  "dns": {:hex, :dns, "2.3.0", "3e750cf3e229898628a091fa7dca29524294db2962d0fc15696ac3a5cfff2315", [:mix], [{:socket, "~> 0.3.13", [hex: :socket, repo: "hexpm", optional: false]}], "hexpm", "f3f1074409b4ecf6f93379a49fb0aef30a898f3093ea22b5c64a85e9f99ca6f8"},
   "erlex": {:hex, :erlex, "0.2.6", "c7987d15e899c7a2f34f5420d2a2ea0d659682c06ac607572df55a43753aa12e", [:mix], [], "hexpm", "2ed2e25711feb44d52b17d2780eabf998452f6efda104877a3881c2f8c0c0c75"},
   "ex_abi": {:hex, :ex_abi, "0.5.11", "a53307cf796231bf068a9941d57fbcb8654e72042c2a113a49f08dfb248875fb", [:mix], [{:ex_keccak, "~> 0.4.0", [hex: :ex_keccak, repo: "hexpm", optional: false]}, {:jason, "~> 1.3", [hex: :jason, repo: "hexpm", optional: false]}], "hexpm", "e128577740bdc0f05ed6841cbb1c88bb80377613970ed870fa052b780870655a"},
   "ex_keccak": {:hex, :ex_keccak, "0.4.0", "4eb8620c8a20a546e2d297b5ce3de150a90db0fdc4ba1dd88c854ace9ee47603", [:mix], [{:rustler, "~> 0.24", [hex: :rustler, repo: "hexpm", optional: false]}], "hexpm", "209ec5591d3cf79f9bdcdedf39c3d7a1fb208321e2b6de2660801117ae386f10"},
@@ -17,6 +18,7 @@
   "mimerl": {:hex, :mimerl, "1.2.0", "67e2d3f571088d5cfd3e550c383094b47159f3eee8ffa08e64106cdf5e981be3", [:rebar3], [], "hexpm", "f278585650aa581986264638ebf698f8bb19df297f66ad91b18910dfc6e19323"},
   "parse_trans": {:hex, :parse_trans, "3.3.1", "16328ab840cc09919bd10dab29e431da3af9e9e7e7e6f0089dd5a2d2820011d8", [:rebar3], [], "hexpm", "07cd9577885f56362d414e8c4c4e6bdf10d43a8767abb92d24cbe8b24c54888b"},
   "rustler": {:hex, :rustler, "0.25.0", "32526b51af7e58a740f61941bf923486ce6415a91c3934cc16c281aa201a2240", [:mix], [{:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: false]}, {:toml, "~> 0.6", [hex: :toml, repo: "hexpm", optional: false]}], "hexpm", "6b43a11a37fe79c6234d88c4102ab5dfede7a6a764dc5c7b539956cfa02f3cf4"},
+  "socket": {:hex, :socket, "0.3.13", "98a2ab20ce17f95fb512c5cadddba32b57273e0d2dba2d2e5f976c5969d0c632", [:mix], [], "hexpm", "f82ea9833ef49dde272e6568ab8aac657a636acb4cf44a7de8a935acb8957c2e"},
   "ssl_verify_fun": {:hex, :ssl_verify_fun, "1.1.6", "cf344f5692c82d2cd7554f5ec8fd961548d4fd09e7d22f5b62482e5aeaebd4b0", [:make, :mix, :rebar3], [], "hexpm", "bdb0d2471f453c88ff3908e7686f86f9be327d065cc1ec16fa4540197ea04680"},
   "tesla": {:hex, :tesla, "1.4.4", "bb89aa0c9745190930366f6a2ac612cdf2d0e4d7fff449861baa7875afd797b2", [:mix], [{:castore, "~> 0.1", [hex: :castore, repo: "hexpm", optional: true]}, {:exjsx, ">= 3.0.0", [hex: :exjsx, repo: "hexpm", optional: true]}, {:finch, "~> 0.3", [hex: :finch, repo: "hexpm", optional: true]}, {:fuse, "~> 2.4", [hex: :fuse, repo: "hexpm", optional: true]}, {:gun, "~> 1.3", [hex: :gun, repo: "hexpm", optional: true]}, {:hackney, "~> 1.6", [hex: :hackney, repo: "hexpm", optional: true]}, {:ibrowse, "4.4.0", [hex: :ibrowse, repo: "hexpm", optional: true]}, {:jason, ">= 1.0.0", [hex: :jason, repo: "hexpm", optional: true]}, {:mime, "~> 1.0 or ~> 2.0", [hex: :mime, repo: "hexpm", optional: false]}, {:mint, "~> 1.0", [hex: :mint, repo: "hexpm", optional: true]}, {:poison, ">= 1.0.0", [hex: :poison, repo: "hexpm", optional: true]}, {:telemetry, "~> 0.4 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: true]}], "hexpm", "d5503a49f9dec1b287567ea8712d085947e247cb11b06bc54adb05bfde466457"},
   "toml": {:hex, :toml, "0.6.2", "38f445df384a17e5d382befe30e3489112a48d3ba4c459e543f748c2f25dd4d1", [:mix], [], "hexpm", "d013e45126d74c0c26a38d31f5e8e9b83ea19fc752470feb9a86071ca5a672fa"},

From f1b0c9ca18b73390c279ea22b1aaa98bc4065707 Mon Sep 17 00:00:00 2001
From: gabrielbosio <gabrielbosio95@gmail.com>
Date: Thu, 19 May 2022 19:19:45 -0300
Subject: [PATCH 02/13] Add moduledoc

---
 eth_client/lib/eth_client/nodes_list.ex | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/eth_client/lib/eth_client/nodes_list.ex b/eth_client/lib/eth_client/nodes_list.ex
index ac56774..70536ee 100644
--- a/eth_client/lib/eth_client/nodes_list.ex
+++ b/eth_client/lib/eth_client/nodes_list.ex
@@ -1,4 +1,9 @@
 defmodule EthClient.NodesList do
+  @moduledoc """
+  Retrieve a nodes list for a specific network. Right now, only supports getting a list
+  by DNS.
+  """
+
   alias DNS.Record
   alias DNS.Resource
 

From e344352ceae124de2810de911b159aa9c8c146b1 Mon Sep 17 00:00:00 2001
From: gabrielbosio <gabrielbosio95@gmail.com>
Date: Fri, 20 May 2022 18:15:04 -0300
Subject: [PATCH 03/13] Add nodes tree search

Add search so that it returns all the nodes from a network.
Mainnet is taking too long. I will try to refactor the module to make it a
bit faster. For example, by removing the list concatenation at line 64.
---
 eth_client/lib/eth_client/nodes_list.ex | 62 ++++++++++++++++++++++---
 1 file changed, 55 insertions(+), 7 deletions(-)

diff --git a/eth_client/lib/eth_client/nodes_list.ex b/eth_client/lib/eth_client/nodes_list.ex
index 70536ee..990d33a 100644
--- a/eth_client/lib/eth_client/nodes_list.ex
+++ b/eth_client/lib/eth_client/nodes_list.ex
@@ -4,19 +4,67 @@ defmodule EthClient.NodesList do
   by DNS.
   """
 
-  alias DNS.Record
-  alias DNS.Resource
-
   @type network :: :mainnet | :ropsten | :rinkeby | :goerli
 
-  @spec get_by_dns(network()) :: Record.t()
+  @enr_prefix "enr:"
+  @enrtree_branch_prefix "enrtree-branch:"
+
+  @spec get_by_dns(network()) :: {:ok, String.t()} | {:error, term()}
   def get_by_dns(network) do
-    %Record{anlist: [%Resource{data: [enrtree_data]}]} =
+    with {:ok, enr_root} <- get_root(network) do
+      get_children(network, enr_root)
+    end
+  end
+
+  @spec get_root(network()) :: {:ok, String.t()} | {:error, term()}
+  defp get_root(network) do
+    {:ok, response_splitted} =
       network
       |> get_domain_name()
-      |> DNS.query(:txt)
+      |> DNS.resolve(:txt)
+
+    response = Enum.join(response_splitted)
+
+    case Regex.run(~r/^enrtree-root:v1 e=([\w\d]+) .*$/, response) do
+      [^response, enr_root] -> {:ok, enr_root}
+      nil -> {:error, "enr_root not found in DNS response: #{response}"}
+    end
+  end
+
+  @spec get_children(network(), String.t()) :: {:ok, [String.t()]} | {:error, term()}
+  defp get_children(network, branch) do
+    branch_domain_name = branch <> "." <> get_domain_name(network)
+    {:ok, response_splitted} = DNS.resolve(branch_domain_name, :txt)
+    response = Enum.join(response_splitted)
+
+    cond do
+      String.starts_with?(response, @enr_prefix) ->
+        @enr_prefix <> node = response
+        {:ok, [node]}
+
+      String.starts_with?(response, @enrtree_branch_prefix) ->
+        @enrtree_branch_prefix <> branches = response
+        branches_splitted = String.split(branches, ",")
+        get_children_branches(network, branches_splitted, [])
+
+      true ->
+        {:error,
+         "Neither #{@enr_prefix} nor #{@enrtree_branch_prefix} is in DNS response: #{response}"}
+    end
+  end
+
+  @spec get_children_branches(network(), [String.t()], [String.t()]) ::
+          {:ok, [String.t()]} | {:error, term()}
+  defp get_children_branches(_network, [], nodes), do: {:ok, nodes}
+
+  defp get_children_branches(network, branches, nodes) do
+    [branch | rest] = branches
 
-    enrtree_data
+    with {:ok, node} <- get_children(network, branch) do
+      get_children_branches(network, rest, node ++ nodes)
+    else
+      {:error, _} = error -> error
+    end
   end
 
   @spec get_domain_name(network()) :: String.t()

From 95452da49354b42e38084caf9cd5896e7baf17ce Mon Sep 17 00:00:00 2001
From: gabrielbosio <gabrielbosio95@gmail.com>
Date: Fri, 20 May 2022 18:19:43 -0300
Subject: [PATCH 04/13] Replace one-clause 'with' with case

---
 eth_client/lib/eth_client/nodes_list.ex | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/eth_client/lib/eth_client/nodes_list.ex b/eth_client/lib/eth_client/nodes_list.ex
index 990d33a..c27b6b3 100644
--- a/eth_client/lib/eth_client/nodes_list.ex
+++ b/eth_client/lib/eth_client/nodes_list.ex
@@ -60,10 +60,12 @@ defmodule EthClient.NodesList do
   defp get_children_branches(network, branches, nodes) do
     [branch | rest] = branches
 
-    with {:ok, node} <- get_children(network, branch) do
-      get_children_branches(network, rest, node ++ nodes)
-    else
-      {:error, _} = error -> error
+    case get_children(network, branch) do
+      {:ok, node} ->
+        get_children_branches(network, rest, node ++ nodes)
+
+      {:error, _} = error ->
+        error
     end
   end
 

From 56c5323a8a92f1bc2e2c514dfae6a3f8f1b850d2 Mon Sep 17 00:00:00 2001
From: gabrielbosio <gabrielbosio95@gmail.com>
Date: Tue, 24 May 2022 12:38:12 -0300
Subject: [PATCH 05/13] Paralellize tree search

---
 eth_client/lib/eth_client/application.ex    |  3 +-
 eth_client/lib/eth_client/nodes_list.ex     | 86 +++++++--------------
 eth_client/lib/eth_client/nodes_list/dns.ex | 75 ++++++++++++++++++
 eth_client/lib/eth_client/nodes_list_old.ex | 78 +++++++++++++++++++
 4 files changed, 185 insertions(+), 57 deletions(-)
 create mode 100644 eth_client/lib/eth_client/nodes_list/dns.ex
 create mode 100644 eth_client/lib/eth_client/nodes_list_old.ex

diff --git a/eth_client/lib/eth_client/application.ex b/eth_client/lib/eth_client/application.ex
index b0f7108..f41b2fa 100644
--- a/eth_client/lib/eth_client/application.ex
+++ b/eth_client/lib/eth_client/application.ex
@@ -22,7 +22,8 @@ defmodule EthClient.Application do
     }
 
     children = [
-      {EthClient.Context, initial_context}
+      {EthClient.Context, initial_context},
+      {EthClient.NodesList, EthClient.NodesList.DNS.Storage}
     ]
 
     # See https://hexdocs.pm/elixir/Supervisor.html
diff --git a/eth_client/lib/eth_client/nodes_list.ex b/eth_client/lib/eth_client/nodes_list.ex
index c27b6b3..3f1ff06 100644
--- a/eth_client/lib/eth_client/nodes_list.ex
+++ b/eth_client/lib/eth_client/nodes_list.ex
@@ -3,75 +3,49 @@ defmodule EthClient.NodesList do
   Retrieve a nodes list for a specific network. Right now, only supports getting a list
   by DNS.
   """
+  use GenServer
 
-  @type network :: :mainnet | :ropsten | :rinkeby | :goerli
+  alias EthClient.NodesList.DNS, as: NodesListDNS
 
-  @enr_prefix "enr:"
-  @enrtree_branch_prefix "enrtree-branch:"
+  @type network :: :mainnet | :ropsten | :rinkeby | :goerli
 
-  @spec get_by_dns(network()) :: {:ok, String.t()} | {:error, term()}
-  def get_by_dns(network) do
-    with {:ok, enr_root} <- get_root(network) do
-      get_children(network, enr_root)
-    end
+  def start_link(storage_name) do
+    GenServer.start_link(__MODULE__, storage_name, name: __MODULE__)
   end
 
-  @spec get_root(network()) :: {:ok, String.t()} | {:error, term()}
-  defp get_root(network) do
-    {:ok, response_splitted} =
-      network
-      |> get_domain_name()
-      |> DNS.resolve(:txt)
-
-    response = Enum.join(response_splitted)
-
-    case Regex.run(~r/^enrtree-root:v1 e=([\w\d]+) .*$/, response) do
-      [^response, enr_root] -> {:ok, enr_root}
-      nil -> {:error, "enr_root not found in DNS response: #{response}"}
-    end
+  @spec update_using_dns(network()) :: :ok | {:error, term()}
+  def update_using_dns(network) do
+    GenServer.call(__MODULE__, {:update_using_dns, network})
   end
 
-  @spec get_children(network(), String.t()) :: {:ok, [String.t()]} | {:error, term()}
-  defp get_children(network, branch) do
-    branch_domain_name = branch <> "." <> get_domain_name(network)
-    {:ok, response_splitted} = DNS.resolve(branch_domain_name, :txt)
-    response = Enum.join(response_splitted)
-
-    cond do
-      String.starts_with?(response, @enr_prefix) ->
-        @enr_prefix <> node = response
-        {:ok, [node]}
+  def get(network) do
+    GenServer.call(__MODULE__, {:get, network})
+  end
 
-      String.starts_with?(response, @enrtree_branch_prefix) ->
-        @enrtree_branch_prefix <> branches = response
-        branches_splitted = String.split(branches, ",")
-        get_children_branches(network, branches_splitted, [])
+  ## Server callbacks
 
-      true ->
-        {:error,
-         "Neither #{@enr_prefix} nor #{@enrtree_branch_prefix} is in DNS response: #{response}"}
-    end
+  @impl true
+  def init(storage_name) do
+    nodes = :ets.new(storage_name, [:named_table, :public, read_concurrency: true])
+    dns_supervisor_name = NodesListDNS.supervisor_name()
+    Task.Supervisor.start_link(name: dns_supervisor_name)
+    {:ok, nodes}
   end
 
-  @spec get_children_branches(network(), [String.t()], [String.t()]) ::
-          {:ok, [String.t()]} | {:error, term()}
-  defp get_children_branches(_network, [], nodes), do: {:ok, nodes}
+  @impl true
+  def handle_call({:update_using_dns, network}, _from, nodes) do
+    result =
+      with {:ok, enr_root} <- NodesListDNS.get_root(network) do
+        NodesListDNS.search_for_nodes(network, nodes, enr_root)
+      end
 
-  defp get_children_branches(network, branches, nodes) do
-    [branch | rest] = branches
+    {:reply, result, nodes}
+  end
 
-    case get_children(network, branch) do
-      {:ok, node} ->
-        get_children_branches(network, rest, node ++ nodes)
+  @impl true
+  def handle_call({:get, network}, _from, nodes) do
+    result = NodesListDNS.get_nodes(network, nodes)
 
-      {:error, _} = error ->
-        error
-    end
+    {:reply, result, nodes}
   end
-
-  @spec get_domain_name(network()) :: String.t()
-  defp get_domain_name(:mainnet), do: "all.mainnet.ethdisco.net"
-  defp get_domain_name(:ropsten), do: "all.ropsten.ethdisco.net"
-  defp get_domain_name(:rinkeby), do: "all.rinkeby.ethdisco.net"
-  defp get_domain_name(:goerli), do: "all.goerli.ethdisco.net"
 end
diff --git a/eth_client/lib/eth_client/nodes_list/dns.ex b/eth_client/lib/eth_client/nodes_list/dns.ex
new file mode 100644
index 0000000..4c899b6
--- /dev/null
+++ b/eth_client/lib/eth_client/nodes_list/dns.ex
@@ -0,0 +1,75 @@
+defmodule EthClient.NodesList.DNS do
+  alias EthClient.NodesList
+
+  @enr_prefix "enr:"
+  @enrtree_branch_prefix "enrtree-branch:"
+
+  def search_for_nodes(network, nodes, enr_root) do
+    supervisor_name()
+    |> Task.Supervisor.start_child(fn ->
+      get_children(network, nodes, enr_root)
+    end)
+  end
+
+  def supervisor_name, do: EthClient.NodesList.DNS.Supervisor
+
+  @spec get_root(NodesList.network()) :: {:ok, String.t()} | {:error, term()}
+  def get_root(network) do
+    {:ok, response_split} =
+      network
+      |> get_domain_name()
+      |> DNS.resolve(:txt)
+
+    response = Enum.join(response_split)
+
+    case Regex.run(~r/^enrtree-root:v1 e=([\w\d]+) .*$/, response) do
+      [^response, enr_root] -> {:ok, enr_root}
+      nil -> {:error, "enr_root not found in DNS response: #{response}"}
+    end
+  end
+
+  def get_nodes(network, nodes), do: :ets.lookup(nodes, network)
+
+  @spec get_children(NodesList.network(), atom(), String.t()) :: :ok | {:error, term()}
+  defp get_children(network, nodes, branch) do
+    branch_domain_name = branch <> "." <> get_domain_name(network)
+    {:ok, response_split} = DNS.resolve(branch_domain_name, :txt)
+    response = Enum.join(response_split)
+    parse_child(network, nodes, response)
+  end
+
+  @spec parse_child(NodesList.network(), atom(), String.t()) :: :ok | {:error, term()}
+  defp parse_child(network, nodes, @enr_prefix <> new_node) do
+    network_nodes =
+      case get_nodes(network, nodes) do
+        [{_, result}] -> result
+        [] -> []
+      end
+
+    :ets.insert(nodes, {network, [new_node | network_nodes]})
+  end
+
+  defp parse_child(network, nodes, @enrtree_branch_prefix <> branches) do
+    branches_split = String.split(branches, ",")
+    get_children_branches(network, nodes, branches_split)
+  end
+
+  defp parse_child(_, _, response) do
+    {:error,
+     "Neither #{@enr_prefix} nor #{@enrtree_branch_prefix} is in DNS response: #{response}"}
+  end
+
+  @spec get_children_branches(NodesList.network(), atom(), [String.t()]) :: :ok | {:error, term()}
+  defp get_children_branches(_network, _, []), do: :ok
+
+  defp get_children_branches(network, nodes, [first_branch | rest]) do
+    {:ok, _pid} = search_for_nodes(network, nodes, first_branch)
+    get_children_branches(network, nodes, rest)
+  end
+
+  @spec get_domain_name(NodesList.network()) :: String.t()
+  defp get_domain_name(:mainnet), do: "all.mainnet.ethdisco.net"
+  defp get_domain_name(:ropsten), do: "all.ropsten.ethdisco.net"
+  defp get_domain_name(:rinkeby), do: "all.rinkeby.ethdisco.net"
+  defp get_domain_name(:goerli), do: "all.goerli.ethdisco.net"
+end
diff --git a/eth_client/lib/eth_client/nodes_list_old.ex b/eth_client/lib/eth_client/nodes_list_old.ex
new file mode 100644
index 0000000..31ce178
--- /dev/null
+++ b/eth_client/lib/eth_client/nodes_list_old.ex
@@ -0,0 +1,78 @@
+defmodule EthClient.NodesListOld do
+  @moduledoc """
+  Retrieve a nodes list for a specific network. Right now, only supports getting a list
+  by DNS.
+  """
+
+  @type network :: :mainnet | :ropsten | :rinkeby | :goerli
+
+  @enr_prefix "enr:"
+  @enrtree_branch_prefix "enrtree-branch:"
+
+  # Probar con :ets, ir guardando los nodos sobre la marcha
+  @spec get_by_dns(network()) :: {:ok, String.t()} | {:error, term()}
+  def get_by_dns(network) do
+    with {:ok, enr_root} <- get_root(network) do
+      get_children(network, enr_root)
+    end
+  end
+
+  @spec get_root(network()) :: {:ok, String.t()} | {:error, term()}
+  defp get_root(network) do
+    {:ok, response_splitted} =
+      network
+      |> get_domain_name()
+      |> DNS.resolve(:txt)
+
+    response = Enum.join(response_splitted)
+
+    case Regex.run(~r/^enrtree-root:v1 e=([\w\d]+) .*$/, response) do
+      [^response, enr_root] -> {:ok, enr_root}
+      nil -> {:error, "enr_root not found in DNS response: #{response}"}
+    end
+  end
+
+  @spec get_children(network(), String.t()) :: {:ok, [String.t()]} | {:error, term()}
+  defp get_children(network, branch) do
+    branch_domain_name = branch <> "." <> get_domain_name(network)
+    {:ok, response_splitted} = DNS.resolve(branch_domain_name, :txt)
+    response = Enum.join(response_splitted)
+
+    cond do
+      String.starts_with?(response, @enr_prefix) ->
+        @enr_prefix <> node = response
+        {:ok, [node]}
+
+      String.starts_with?(response, @enrtree_branch_prefix) ->
+        @enrtree_branch_prefix <> branches = response
+        branches_splitted = String.split(branches, ",")
+        get_children_branches(network, branches_splitted, [])
+
+      true ->
+        {:error,
+         "Neither #{@enr_prefix} nor #{@enrtree_branch_prefix} is in DNS response: #{response}"}
+    end
+  end
+
+  @spec get_children_branches(network(), [String.t()], [String.t()]) ::
+          {:ok, [String.t()]} | {:error, term()}
+  defp get_children_branches(_network, [], nodes), do: {:ok, nodes}
+
+  defp get_children_branches(network, branches, nodes) do
+    [branch | rest] = branches
+
+    case get_children(network, branch) do
+      {:ok, new_nodes} ->
+        get_children_branches(network, rest, new_nodes ++ nodes)
+
+      {:error, _} = error ->
+        error
+    end
+  end
+
+  @spec get_domain_name(network()) :: String.t()
+  defp get_domain_name(:mainnet), do: "all.mainnet.ethdisco.net"
+  defp get_domain_name(:ropsten), do: "all.ropsten.ethdisco.net"
+  defp get_domain_name(:rinkeby), do: "all.rinkeby.ethdisco.net"
+  defp get_domain_name(:goerli), do: "all.goerli.ethdisco.net"
+end

From 4d2e0a967888b550a8e0cfec850db1d800e9f635 Mon Sep 17 00:00:00 2001
From: gabrielbosio <gabrielbosio95@gmail.com>
Date: Tue, 24 May 2022 13:02:22 -0300
Subject: [PATCH 06/13] Refactor ETS handling into new module

---
 eth_client/lib/eth_client/nodes_list.ex       | 20 ++++++-----
 eth_client/lib/eth_client/nodes_list/dns.ex   | 35 +++++++++----------
 .../lib/eth_client/nodes_list/storage.ex      | 24 +++++++++++++
 3 files changed, 52 insertions(+), 27 deletions(-)
 create mode 100644 eth_client/lib/eth_client/nodes_list/storage.ex

diff --git a/eth_client/lib/eth_client/nodes_list.ex b/eth_client/lib/eth_client/nodes_list.ex
index 3f1ff06..6f8a31e 100644
--- a/eth_client/lib/eth_client/nodes_list.ex
+++ b/eth_client/lib/eth_client/nodes_list.ex
@@ -1,11 +1,12 @@
 defmodule EthClient.NodesList do
   @moduledoc """
-  Retrieve a nodes list for a specific network. Right now, only supports getting a list
+  Retrieve a storage list for a specific network. Right now, only supports getting a list
   by DNS.
   """
   use GenServer
 
   alias EthClient.NodesList.DNS, as: NodesListDNS
+  alias EthClient.NodesList.Storage
 
   @type network :: :mainnet | :ropsten | :rinkeby | :goerli
 
@@ -18,6 +19,7 @@ defmodule EthClient.NodesList do
     GenServer.call(__MODULE__, {:update_using_dns, network})
   end
 
+  @spec get(network()) :: :ok | {:error, term()}
   def get(network) do
     GenServer.call(__MODULE__, {:get, network})
   end
@@ -26,26 +28,26 @@ defmodule EthClient.NodesList do
 
   @impl true
   def init(storage_name) do
-    nodes = :ets.new(storage_name, [:named_table, :public, read_concurrency: true])
+    storage = Storage.new(storage_name)
     dns_supervisor_name = NodesListDNS.supervisor_name()
     Task.Supervisor.start_link(name: dns_supervisor_name)
-    {:ok, nodes}
+    {:ok, storage}
   end
 
   @impl true
-  def handle_call({:update_using_dns, network}, _from, nodes) do
+  def handle_call({:update_using_dns, network}, _from, storage) do
     result =
       with {:ok, enr_root} <- NodesListDNS.get_root(network) do
-        NodesListDNS.search_for_nodes(network, nodes, enr_root)
+        NodesListDNS.search_for_nodes(network, storage, enr_root)
       end
 
-    {:reply, result, nodes}
+    {:reply, result, storage}
   end
 
   @impl true
-  def handle_call({:get, network}, _from, nodes) do
-    result = NodesListDNS.get_nodes(network, nodes)
+  def handle_call({:get, network}, _from, storage) do
+    result = NodesListDNS.get_nodes(network, storage)
 
-    {:reply, result, nodes}
+    {:reply, result, storage}
   end
 end
diff --git a/eth_client/lib/eth_client/nodes_list/dns.ex b/eth_client/lib/eth_client/nodes_list/dns.ex
index 4c899b6..2a426d0 100644
--- a/eth_client/lib/eth_client/nodes_list/dns.ex
+++ b/eth_client/lib/eth_client/nodes_list/dns.ex
@@ -1,13 +1,17 @@
 defmodule EthClient.NodesList.DNS do
+  @moduledoc """
+  Module for handling storage list retrieval using DNS.
+  """
   alias EthClient.NodesList
+  alias EthClient.NodesList.Storage
 
   @enr_prefix "enr:"
   @enrtree_branch_prefix "enrtree-branch:"
 
-  def search_for_nodes(network, nodes, enr_root) do
+  def search_for_nodes(network, storage, enr_root) do
     supervisor_name()
     |> Task.Supervisor.start_child(fn ->
-      get_children(network, nodes, enr_root)
+      get_children(network, storage, enr_root)
     end)
   end
 
@@ -28,30 +32,25 @@ defmodule EthClient.NodesList.DNS do
     end
   end
 
-  def get_nodes(network, nodes), do: :ets.lookup(nodes, network)
+  @spec get_nodes(NodesList.network(), :ets.tid()) :: [tuple()]
+  def get_nodes(network, storage), do: Storage.lookup(storage, network)
 
   @spec get_children(NodesList.network(), atom(), String.t()) :: :ok | {:error, term()}
-  defp get_children(network, nodes, branch) do
+  defp get_children(network, storage, branch) do
     branch_domain_name = branch <> "." <> get_domain_name(network)
     {:ok, response_split} = DNS.resolve(branch_domain_name, :txt)
     response = Enum.join(response_split)
-    parse_child(network, nodes, response)
+    parse_child(network, storage, response)
   end
 
   @spec parse_child(NodesList.network(), atom(), String.t()) :: :ok | {:error, term()}
-  defp parse_child(network, nodes, @enr_prefix <> new_node) do
-    network_nodes =
-      case get_nodes(network, nodes) do
-        [{_, result}] -> result
-        [] -> []
-      end
-
-    :ets.insert(nodes, {network, [new_node | network_nodes]})
+  defp parse_child(network, storage, @enr_prefix <> new_node) do
+    Storage.insert(storage, network, new_node)
   end
 
-  defp parse_child(network, nodes, @enrtree_branch_prefix <> branches) do
+  defp parse_child(network, storage, @enrtree_branch_prefix <> branches) do
     branches_split = String.split(branches, ",")
-    get_children_branches(network, nodes, branches_split)
+    get_children_branches(network, storage, branches_split)
   end
 
   defp parse_child(_, _, response) do
@@ -62,9 +61,9 @@ defmodule EthClient.NodesList.DNS do
   @spec get_children_branches(NodesList.network(), atom(), [String.t()]) :: :ok | {:error, term()}
   defp get_children_branches(_network, _, []), do: :ok
 
-  defp get_children_branches(network, nodes, [first_branch | rest]) do
-    {:ok, _pid} = search_for_nodes(network, nodes, first_branch)
-    get_children_branches(network, nodes, rest)
+  defp get_children_branches(network, storage, [first_branch | rest]) do
+    {:ok, _pid} = search_for_nodes(network, storage, first_branch)
+    get_children_branches(network, storage, rest)
   end
 
   @spec get_domain_name(NodesList.network()) :: String.t()
diff --git a/eth_client/lib/eth_client/nodes_list/storage.ex b/eth_client/lib/eth_client/nodes_list/storage.ex
new file mode 100644
index 0000000..dd98f42
--- /dev/null
+++ b/eth_client/lib/eth_client/nodes_list/storage.ex
@@ -0,0 +1,24 @@
+defmodule EthClient.NodesList.Storage do
+  @moduledoc """
+  Module for handling nodes list storage.
+  """
+  @spec new(atom) :: :ets.tid()
+  def new(name) do
+    :ets.new(name, [:named_table, :public, read_concurrency: true])
+  end
+
+  @spec lookup(:ets.tid(), String.t()) :: [tuple()]
+  def lookup(storage, network) do
+    :ets.lookup(storage, network)
+  end
+
+  def insert(storage, network, new_node) do
+    network_nodes =
+      case lookup(storage, network) do
+        [{_, result}] -> result
+        [] -> []
+      end
+
+    :ets.insert(storage, {network, [new_node | network_nodes]})
+  end
+end

From 286a77b3d7e98c0b627c1234f57063632067a9d9 Mon Sep 17 00:00:00 2001
From: gabrielbosio <gabrielbosio95@gmail.com>
Date: Tue, 24 May 2022 13:32:56 -0300
Subject: [PATCH 07/13] Fix dialyzer in DNS modules

---
 eth_client/lib/eth_client/nodes_list/dns.ex     | 6 +-----
 eth_client/lib/eth_client/nodes_list/storage.ex | 3 +--
 2 files changed, 2 insertions(+), 7 deletions(-)

diff --git a/eth_client/lib/eth_client/nodes_list/dns.ex b/eth_client/lib/eth_client/nodes_list/dns.ex
index 2a426d0..1b87bd1 100644
--- a/eth_client/lib/eth_client/nodes_list/dns.ex
+++ b/eth_client/lib/eth_client/nodes_list/dns.ex
@@ -17,7 +17,6 @@ defmodule EthClient.NodesList.DNS do
 
   def supervisor_name, do: EthClient.NodesList.DNS.Supervisor
 
-  @spec get_root(NodesList.network()) :: {:ok, String.t()} | {:error, term()}
   def get_root(network) do
     {:ok, response_split} =
       network
@@ -32,10 +31,8 @@ defmodule EthClient.NodesList.DNS do
     end
   end
 
-  @spec get_nodes(NodesList.network(), :ets.tid()) :: [tuple()]
   def get_nodes(network, storage), do: Storage.lookup(storage, network)
 
-  @spec get_children(NodesList.network(), atom(), String.t()) :: :ok | {:error, term()}
   defp get_children(network, storage, branch) do
     branch_domain_name = branch <> "." <> get_domain_name(network)
     {:ok, response_split} = DNS.resolve(branch_domain_name, :txt)
@@ -43,9 +40,9 @@ defmodule EthClient.NodesList.DNS do
     parse_child(network, storage, response)
   end
 
-  @spec parse_child(NodesList.network(), atom(), String.t()) :: :ok | {:error, term()}
   defp parse_child(network, storage, @enr_prefix <> new_node) do
     Storage.insert(storage, network, new_node)
+    :ok
   end
 
   defp parse_child(network, storage, @enrtree_branch_prefix <> branches) do
@@ -58,7 +55,6 @@ defmodule EthClient.NodesList.DNS do
      "Neither #{@enr_prefix} nor #{@enrtree_branch_prefix} is in DNS response: #{response}"}
   end
 
-  @spec get_children_branches(NodesList.network(), atom(), [String.t()]) :: :ok | {:error, term()}
   defp get_children_branches(_network, _, []), do: :ok
 
   defp get_children_branches(network, storage, [first_branch | rest]) do
diff --git a/eth_client/lib/eth_client/nodes_list/storage.ex b/eth_client/lib/eth_client/nodes_list/storage.ex
index dd98f42..701c85b 100644
--- a/eth_client/lib/eth_client/nodes_list/storage.ex
+++ b/eth_client/lib/eth_client/nodes_list/storage.ex
@@ -2,12 +2,11 @@ defmodule EthClient.NodesList.Storage do
   @moduledoc """
   Module for handling nodes list storage.
   """
-  @spec new(atom) :: :ets.tid()
+
   def new(name) do
     :ets.new(name, [:named_table, :public, read_concurrency: true])
   end
 
-  @spec lookup(:ets.tid(), String.t()) :: [tuple()]
   def lookup(storage, network) do
     :ets.lookup(storage, network)
   end

From 3f5f1a00d59419b9b85eca60c0a07b03fa263447 Mon Sep 17 00:00:00 2001
From: gabrielbosio <gabrielbosio95@gmail.com>
Date: Tue, 24 May 2022 13:59:43 -0300
Subject: [PATCH 08/13] Add wait to DNS requests to resolve

---
 eth_client/lib/eth_client/nodes_list.ex       |  2 +-
 eth_client/lib/eth_client/nodes_list/dns.ex   | 43 ++++++++++++++++---
 .../lib/eth_client/nodes_list/storage.ex      |  4 ++
 3 files changed, 42 insertions(+), 7 deletions(-)

diff --git a/eth_client/lib/eth_client/nodes_list.ex b/eth_client/lib/eth_client/nodes_list.ex
index 6f8a31e..499c369 100644
--- a/eth_client/lib/eth_client/nodes_list.ex
+++ b/eth_client/lib/eth_client/nodes_list.ex
@@ -38,7 +38,7 @@ defmodule EthClient.NodesList do
   def handle_call({:update_using_dns, network}, _from, storage) do
     result =
       with {:ok, enr_root} <- NodesListDNS.get_root(network) do
-        NodesListDNS.search_for_nodes(network, storage, enr_root)
+        NodesListDNS.start_searching_for_nodes(network, storage, enr_root)
       end
 
     {:reply, result, storage}
diff --git a/eth_client/lib/eth_client/nodes_list/dns.ex b/eth_client/lib/eth_client/nodes_list/dns.ex
index 1b87bd1..ba5e1e2 100644
--- a/eth_client/lib/eth_client/nodes_list/dns.ex
+++ b/eth_client/lib/eth_client/nodes_list/dns.ex
@@ -7,12 +7,12 @@ defmodule EthClient.NodesList.DNS do
 
   @enr_prefix "enr:"
   @enrtree_branch_prefix "enrtree-branch:"
+  @attempts 100
+  @waiting_time_ms 500
 
-  def search_for_nodes(network, storage, enr_root) do
-    supervisor_name()
-    |> Task.Supervisor.start_child(fn ->
-      get_children(network, storage, enr_root)
-    end)
+  def start_searching_for_nodes(network, storage, enr_root) do
+    Storage.delete(storage, network)
+    search_for_nodes(network, storage, enr_root)
   end
 
   def supervisor_name, do: EthClient.NodesList.DNS.Supervisor
@@ -33,9 +33,16 @@ defmodule EthClient.NodesList.DNS do
 
   def get_nodes(network, storage), do: Storage.lookup(storage, network)
 
+  defp search_for_nodes(network, storage, node) do
+    supervisor_name()
+    |> Task.Supervisor.start_child(fn ->
+      get_children(network, storage, node)
+    end)
+  end
+
   defp get_children(network, storage, branch) do
     branch_domain_name = branch <> "." <> get_domain_name(network)
-    {:ok, response_split} = DNS.resolve(branch_domain_name, :txt)
+    {:ok, response_split} = wait_to_resolve(branch_domain_name)
     response = Enum.join(response_split)
     parse_child(network, storage, response)
   end
@@ -62,6 +69,30 @@ defmodule EthClient.NodesList.DNS do
     get_children_branches(network, storage, rest)
   end
 
+  defp wait_to_resolve(domain_name), do: wait_to_resolve(domain_name, @attempts)
+
+  defp wait_to_resolve(domain_name, 0), do: {:error, "Cannot resolve #{domain_name}"}
+
+  defp wait_to_resolve(domain_name, attempts) do
+    response =
+      try do
+        try_to_resolve(domain_name, :start)
+      rescue
+        Socket.Error -> {:error, attempts}
+      end
+
+    try_to_resolve(domain_name, response)
+  end
+
+  defp try_to_resolve(domain_name, :start), do: DNS.resolve(domain_name, :txt)
+
+  defp try_to_resolve(domain_name, {:error, attempts}) do
+    Process.sleep(@waiting_time_ms)
+    wait_to_resolve(domain_name, attempts - 1)
+  end
+
+  defp try_to_resolve(_domain_name, {:ok, _} = success), do: success
+
   @spec get_domain_name(NodesList.network()) :: String.t()
   defp get_domain_name(:mainnet), do: "all.mainnet.ethdisco.net"
   defp get_domain_name(:ropsten), do: "all.ropsten.ethdisco.net"
diff --git a/eth_client/lib/eth_client/nodes_list/storage.ex b/eth_client/lib/eth_client/nodes_list/storage.ex
index 701c85b..954df13 100644
--- a/eth_client/lib/eth_client/nodes_list/storage.ex
+++ b/eth_client/lib/eth_client/nodes_list/storage.ex
@@ -20,4 +20,8 @@ defmodule EthClient.NodesList.Storage do
 
     :ets.insert(storage, {network, [new_node | network_nodes]})
   end
+
+  def delete(storage, network) do
+    :ets.delete(storage, network)
+  end
 end

From 428f6940dfcd9704195039c5bd62fa55b334d8a7 Mon Sep 17 00:00:00 2001
From: gabrielbosio <gabrielbosio95@gmail.com>
Date: Tue, 24 May 2022 16:25:49 -0300
Subject: [PATCH 09/13] Add wait for tasks to finish

---
 eth_client/lib/eth_client/nodes_list.ex     |  4 +--
 eth_client/lib/eth_client/nodes_list/dns.ex | 29 +++++++--------------
 2 files changed, 11 insertions(+), 22 deletions(-)

diff --git a/eth_client/lib/eth_client/nodes_list.ex b/eth_client/lib/eth_client/nodes_list.ex
index 499c369..d7c9dc7 100644
--- a/eth_client/lib/eth_client/nodes_list.ex
+++ b/eth_client/lib/eth_client/nodes_list.ex
@@ -16,7 +16,7 @@ defmodule EthClient.NodesList do
 
   @spec update_using_dns(network()) :: :ok | {:error, term()}
   def update_using_dns(network) do
-    GenServer.call(__MODULE__, {:update_using_dns, network})
+    GenServer.call(__MODULE__, {:update_using_dns, network}, :infinity)
   end
 
   @spec get(network()) :: :ok | {:error, term()}
@@ -29,8 +29,6 @@ defmodule EthClient.NodesList do
   @impl true
   def init(storage_name) do
     storage = Storage.new(storage_name)
-    dns_supervisor_name = NodesListDNS.supervisor_name()
-    Task.Supervisor.start_link(name: dns_supervisor_name)
     {:ok, storage}
   end
 
diff --git a/eth_client/lib/eth_client/nodes_list/dns.ex b/eth_client/lib/eth_client/nodes_list/dns.ex
index ba5e1e2..96a3d09 100644
--- a/eth_client/lib/eth_client/nodes_list/dns.ex
+++ b/eth_client/lib/eth_client/nodes_list/dns.ex
@@ -12,11 +12,10 @@ defmodule EthClient.NodesList.DNS do
 
   def start_searching_for_nodes(network, storage, enr_root) do
     Storage.delete(storage, network)
-    search_for_nodes(network, storage, enr_root)
+    search = Task.async(fn -> get_children(network, storage, enr_root) end)
+    Task.await(search, :infinity)
   end
 
-  def supervisor_name, do: EthClient.NodesList.DNS.Supervisor
-
   def get_root(network) do
     {:ok, response_split} =
       network
@@ -33,13 +32,6 @@ defmodule EthClient.NodesList.DNS do
 
   def get_nodes(network, storage), do: Storage.lookup(storage, network)
 
-  defp search_for_nodes(network, storage, node) do
-    supervisor_name()
-    |> Task.Supervisor.start_child(fn ->
-      get_children(network, storage, node)
-    end)
-  end
-
   defp get_children(network, storage, branch) do
     branch_domain_name = branch <> "." <> get_domain_name(network)
     {:ok, response_split} = wait_to_resolve(branch_domain_name)
@@ -53,8 +45,14 @@ defmodule EthClient.NodesList.DNS do
   end
 
   defp parse_child(network, storage, @enrtree_branch_prefix <> branches) do
-    branches_split = String.split(branches, ",")
-    get_children_branches(network, storage, branches_split)
+    branches
+    |> String.split(",")
+    |> Enum.map(fn branch ->
+      Task.async(fn -> get_children(network, storage, branch) end)
+    end)
+    |> Task.await_many(:infinity)
+
+    :ok
   end
 
   defp parse_child(_, _, response) do
@@ -62,13 +60,6 @@ defmodule EthClient.NodesList.DNS do
      "Neither #{@enr_prefix} nor #{@enrtree_branch_prefix} is in DNS response: #{response}"}
   end
 
-  defp get_children_branches(_network, _, []), do: :ok
-
-  defp get_children_branches(network, storage, [first_branch | rest]) do
-    {:ok, _pid} = search_for_nodes(network, storage, first_branch)
-    get_children_branches(network, storage, rest)
-  end
-
   defp wait_to_resolve(domain_name), do: wait_to_resolve(domain_name, @attempts)
 
   defp wait_to_resolve(domain_name, 0), do: {:error, "Cannot resolve #{domain_name}"}

From 3fa9668d33d19c579392a86976ff2cfe7a313592 Mon Sep 17 00:00:00 2001
From: gabrielbosio <gabrielbosio95@gmail.com>
Date: Tue, 24 May 2022 16:50:20 -0300
Subject: [PATCH 10/13] Set finite timeout

Refactor ETS lookup.
---
 eth_client/lib/eth_client/nodes_list.ex         |  4 +++-
 eth_client/lib/eth_client/nodes_list/dns.ex     |  4 ++--
 eth_client/lib/eth_client/nodes_list/storage.ex | 11 ++++-------
 3 files changed, 9 insertions(+), 10 deletions(-)

diff --git a/eth_client/lib/eth_client/nodes_list.ex b/eth_client/lib/eth_client/nodes_list.ex
index d7c9dc7..7d535b5 100644
--- a/eth_client/lib/eth_client/nodes_list.ex
+++ b/eth_client/lib/eth_client/nodes_list.ex
@@ -16,7 +16,7 @@ defmodule EthClient.NodesList do
 
   @spec update_using_dns(network()) :: :ok | {:error, term()}
   def update_using_dns(network) do
-    GenServer.call(__MODULE__, {:update_using_dns, network}, :infinity)
+    GenServer.call(__MODULE__, {:update_using_dns, network}, search_timeout())
   end
 
   @spec get(network()) :: :ok | {:error, term()}
@@ -24,6 +24,8 @@ defmodule EthClient.NodesList do
     GenServer.call(__MODULE__, {:get, network})
   end
 
+  def search_timeout, do: 20000
+
   ## Server callbacks
 
   @impl true
diff --git a/eth_client/lib/eth_client/nodes_list/dns.ex b/eth_client/lib/eth_client/nodes_list/dns.ex
index 96a3d09..0ef1e06 100644
--- a/eth_client/lib/eth_client/nodes_list/dns.ex
+++ b/eth_client/lib/eth_client/nodes_list/dns.ex
@@ -13,7 +13,7 @@ defmodule EthClient.NodesList.DNS do
   def start_searching_for_nodes(network, storage, enr_root) do
     Storage.delete(storage, network)
     search = Task.async(fn -> get_children(network, storage, enr_root) end)
-    Task.await(search, :infinity)
+    Task.await(search, NodesList.search_timeout())
   end
 
   def get_root(network) do
@@ -50,7 +50,7 @@ defmodule EthClient.NodesList.DNS do
     |> Enum.map(fn branch ->
       Task.async(fn -> get_children(network, storage, branch) end)
     end)
-    |> Task.await_many(:infinity)
+    |> Task.await_many(NodesList.search_timeout())
 
     :ok
   end
diff --git a/eth_client/lib/eth_client/nodes_list/storage.ex b/eth_client/lib/eth_client/nodes_list/storage.ex
index 954df13..0df86c1 100644
--- a/eth_client/lib/eth_client/nodes_list/storage.ex
+++ b/eth_client/lib/eth_client/nodes_list/storage.ex
@@ -8,16 +8,13 @@ defmodule EthClient.NodesList.Storage do
   end
 
   def lookup(storage, network) do
-    :ets.lookup(storage, network)
+    with [{^network, nodes}] <- :ets.lookup(storage, network) do
+      nodes
+    end
   end
 
   def insert(storage, network, new_node) do
-    network_nodes =
-      case lookup(storage, network) do
-        [{_, result}] -> result
-        [] -> []
-      end
-
+    network_nodes = lookup(storage, network)
     :ets.insert(storage, {network, [new_node | network_nodes]})
   end
 

From ea8e26f3097bea09f09a140056a2ad8b7c91056c Mon Sep 17 00:00:00 2001
From: gabrielbosio <gabrielbosio95@gmail.com>
Date: Tue, 24 May 2022 16:51:24 -0300
Subject: [PATCH 11/13] Fix credo issue with constant

---
 eth_client/lib/eth_client/nodes_list.ex | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/eth_client/lib/eth_client/nodes_list.ex b/eth_client/lib/eth_client/nodes_list.ex
index 7d535b5..9801445 100644
--- a/eth_client/lib/eth_client/nodes_list.ex
+++ b/eth_client/lib/eth_client/nodes_list.ex
@@ -24,7 +24,7 @@ defmodule EthClient.NodesList do
     GenServer.call(__MODULE__, {:get, network})
   end
 
-  def search_timeout, do: 20000
+  def search_timeout, do: 20_000
 
   ## Server callbacks
 

From 100fdaab233d4e7ea2e67429cd6b52be75e09618 Mon Sep 17 00:00:00 2001
From: gabrielbosio <gabrielbosio95@gmail.com>
Date: Tue, 24 May 2022 18:41:11 -0300
Subject: [PATCH 12/13] Remove old NodesList module

---
 eth_client/lib/eth_client/nodes_list_old.ex | 78 ---------------------
 1 file changed, 78 deletions(-)
 delete mode 100644 eth_client/lib/eth_client/nodes_list_old.ex

diff --git a/eth_client/lib/eth_client/nodes_list_old.ex b/eth_client/lib/eth_client/nodes_list_old.ex
deleted file mode 100644
index 31ce178..0000000
--- a/eth_client/lib/eth_client/nodes_list_old.ex
+++ /dev/null
@@ -1,78 +0,0 @@
-defmodule EthClient.NodesListOld do
-  @moduledoc """
-  Retrieve a nodes list for a specific network. Right now, only supports getting a list
-  by DNS.
-  """
-
-  @type network :: :mainnet | :ropsten | :rinkeby | :goerli
-
-  @enr_prefix "enr:"
-  @enrtree_branch_prefix "enrtree-branch:"
-
-  # Probar con :ets, ir guardando los nodos sobre la marcha
-  @spec get_by_dns(network()) :: {:ok, String.t()} | {:error, term()}
-  def get_by_dns(network) do
-    with {:ok, enr_root} <- get_root(network) do
-      get_children(network, enr_root)
-    end
-  end
-
-  @spec get_root(network()) :: {:ok, String.t()} | {:error, term()}
-  defp get_root(network) do
-    {:ok, response_splitted} =
-      network
-      |> get_domain_name()
-      |> DNS.resolve(:txt)
-
-    response = Enum.join(response_splitted)
-
-    case Regex.run(~r/^enrtree-root:v1 e=([\w\d]+) .*$/, response) do
-      [^response, enr_root] -> {:ok, enr_root}
-      nil -> {:error, "enr_root not found in DNS response: #{response}"}
-    end
-  end
-
-  @spec get_children(network(), String.t()) :: {:ok, [String.t()]} | {:error, term()}
-  defp get_children(network, branch) do
-    branch_domain_name = branch <> "." <> get_domain_name(network)
-    {:ok, response_splitted} = DNS.resolve(branch_domain_name, :txt)
-    response = Enum.join(response_splitted)
-
-    cond do
-      String.starts_with?(response, @enr_prefix) ->
-        @enr_prefix <> node = response
-        {:ok, [node]}
-
-      String.starts_with?(response, @enrtree_branch_prefix) ->
-        @enrtree_branch_prefix <> branches = response
-        branches_splitted = String.split(branches, ",")
-        get_children_branches(network, branches_splitted, [])
-
-      true ->
-        {:error,
-         "Neither #{@enr_prefix} nor #{@enrtree_branch_prefix} is in DNS response: #{response}"}
-    end
-  end
-
-  @spec get_children_branches(network(), [String.t()], [String.t()]) ::
-          {:ok, [String.t()]} | {:error, term()}
-  defp get_children_branches(_network, [], nodes), do: {:ok, nodes}
-
-  defp get_children_branches(network, branches, nodes) do
-    [branch | rest] = branches
-
-    case get_children(network, branch) do
-      {:ok, new_nodes} ->
-        get_children_branches(network, rest, new_nodes ++ nodes)
-
-      {:error, _} = error ->
-        error
-    end
-  end
-
-  @spec get_domain_name(network()) :: String.t()
-  defp get_domain_name(:mainnet), do: "all.mainnet.ethdisco.net"
-  defp get_domain_name(:ropsten), do: "all.ropsten.ethdisco.net"
-  defp get_domain_name(:rinkeby), do: "all.rinkeby.ethdisco.net"
-  defp get_domain_name(:goerli), do: "all.goerli.ethdisco.net"
-end

From fd0b2702154d2ac162ad842a25f0bf492572ede9 Mon Sep 17 00:00:00 2001
From: gabrielbosio <gabrielbosio95@gmail.com>
Date: Thu, 26 May 2022 12:53:16 -0300
Subject: [PATCH 13/13] Add nodes decoding

---
 eth_client/lib/eth_client/nodes_list/dns.ex | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/eth_client/lib/eth_client/nodes_list/dns.ex b/eth_client/lib/eth_client/nodes_list/dns.ex
index 0ef1e06..86450d5 100644
--- a/eth_client/lib/eth_client/nodes_list/dns.ex
+++ b/eth_client/lib/eth_client/nodes_list/dns.ex
@@ -40,7 +40,12 @@ defmodule EthClient.NodesList.DNS do
   end
 
   defp parse_child(network, storage, @enr_prefix <> new_node) do
-    Storage.insert(storage, network, new_node)
+    decoded_node =
+      new_node
+      |> Base.url_decode64!(padding: false)
+      |> ExRLP.decode()
+
+    Storage.insert(storage, network, decoded_node)
     :ok
   end