feat: add stacktrace to SSZ (#1017)

Co-authored-by: Tomás Grüner <47506558+MegaRedHand@users.noreply.github.com>

lib/ssz_ex/decode.ex

@@ -55,7 +55,7 @@ defmodule SszEx.Decode do
       {:error,
        %Error{
          message:
-           "Invalid binary length while decoding uint.\nExpected size: #{size}.\nFound:#{bit_size(binary)}\n"
+           "Invalid binary length while decoding uint.\nExpected size: #{size}.\nFound:#{bit_size(binary)}"
        }}
 
   defp decode_uint(binary, size) do
@@ -68,7 +68,7 @@ defmodule SszEx.Decode do
       {:error,
        %Error{
          message:
-           "Invalid binary length while decoding bool.\nExpected size: 1.\nFound:#{byte_size(binary)}\n"
+           "Invalid binary length while decoding bool.\nExpected size: 1.\nFound:#{byte_size(binary)}"
        }}
 
   defp decode_bool("\x01"), do: {:ok, true}
@@ -86,7 +86,7 @@ defmodule SszEx.Decode do
     do:
       {:error,
        %Error{
-         message: "Invalid binary value while decoding BitList.\nEmpty binary found.\n"
+         message: "Invalid binary value while decoding BitList.\nEmpty binary found."
        }}
 
   defp decode_bitlist(bit_list, max_size) do
@@ -98,14 +98,14 @@ defmodule SszEx.Decode do
       match?(<<_::binary-size(num_bytes - 1), 0>>, bit_list) ->
         {:error,
          %Error{
-           message: "Invalid binary value while decoding BitList.\nMissing sentinel bit.\n"
+           message: "Invalid binary value while decoding BitList.\nMissing sentinel bit."
          }}
 
       len > max_size ->
         {:error,
          %Error{
            message:
-             "Invalid binary length while decoding BitList. \nExpected max_size: #{max_size}. Found: #{len}.\n"
+             "Invalid binary length while decoding BitList. \nExpected max_size: #{max_size}. Found: #{len}."
          }}
 
       true ->
@@ -125,7 +125,7 @@ defmodule SszEx.Decode do
       _ ->
         {:error,
          %Error{
-           message: "Invalid binary length while decoding BitVector. \nExpected size: #{size}.\n"
+           message: "Invalid binary length while decoding BitVector. \nExpected size: #{size}."
          }}
     end
   end
@@ -162,7 +162,7 @@ defmodule SszEx.Decode do
          {:error,
           %Error{
             message:
-              "Invalid binary length while decoding list of #{inspect(inner_type)}.\nExpected max_size: #{max_size}.\nFound: #{byte_length}\n"
+              "Invalid binary length while decoding list of #{inspect(inner_type)}.\nExpected max_size: #{max_size}.\nFound: #{byte_length}"
           }}
 
   defp check_valid_fixed_list_size(_byte_length, _inner_type, _inner_type_size, _max_size),
@@ -174,7 +174,7 @@ defmodule SszEx.Decode do
          {:error,
           %Error{
             message:
-              "Invalid binary length while decoding vector of #{inspect(inner_type)}.\nExpected size #{inner_type_size * size} bytes.\nFound: #{byte_length}.\n"
+              "Invalid binary length while decoding vector of #{inspect(inner_type)}.\nExpected size #{inner_type_size * size} bytes.\nFound: #{byte_length}."
           }}
 
   defp check_valid_vector_size(_byte_length, _inner_type, _inner_type_size, _size),
@@ -310,7 +310,7 @@ defmodule SszEx.Decode do
          {:error,
           %Error{
             message:
-              "Invalid binary length while decoding #{module}. \nExpected #{expected_length}. \nFound #{size}.\n"
+              "Invalid binary length while decoding #{module}. \nExpected #{expected_length}. \nFound #{size}."
           }}
 
   defp check_fixed_container_size(_module, _expected_length, _size),
@@ -322,7 +322,7 @@ defmodule SszEx.Decode do
          {:error,
           %Error{
             message:
-              "First offset does not point to the first variable byte.\nExpected index: #{items_index}.\nOffset: #{offset}. "
+              "First offset does not point to the first variable byte.\nExpected index: #{items_index}.\nOffset: #{offset}."
           }}
 
   defp check_first_offset(_offsets, _items_index, _binary_size),
@@ -337,14 +337,17 @@ defmodule SszEx.Decode do
           :ok ->
             size = next_offset - offset
             <<chunk::binary-size(size), rest::bitstring>> = rest_bytes
-            {:cont, {rest, [{key, decode(chunk, schema)} | acc_variable_parts]}}
+
+            {:cont,
+             {rest, [{key, decode(chunk, schema) |> Error.add_trace(key)} | acc_variable_parts]}}
 
           error ->
             {:halt, {<<>>, [{key, error} | acc_variable_parts]}}
         end
 
       [{_offset, {key, schema}}], {rest_bytes, acc_variable_parts} ->
-        {:cont, {<<>>, [{key, decode(rest_bytes, schema)} | acc_variable_parts]}}
+        {:cont,
+         {<<>>, [{key, decode(rest_bytes, schema) |> Error.add_trace(key)} | acc_variable_parts]}}
     end)
     |> then(fn {<<>>, variable_parts} ->
       flatten_container_results(variable_parts)
@@ -363,7 +366,9 @@ defmodule SszEx.Decode do
       else
         ssz_fixed_len = Utils.get_fixed_size(schema)
         <<chunk::binary-size(ssz_fixed_len), rest::bitstring>> = binary
-        {rest, [{key, decode(chunk, schema)} | fixed_parts], offsets, items_index + ssz_fixed_len}
+
+        {rest, [{key, decode(chunk, schema) |> Error.add_trace(key)} | fixed_parts], offsets,
+         items_index + ssz_fixed_len}
       end
     end)
     |> then(fn {_rest_bytes, fixed_parts, offsets, items_index} ->
@@ -441,7 +446,7 @@ defmodule SszEx.Decode do
          {:error,
           %Error{
             message:
-              "Invalid binary length while decoding collection. \nInner type size: #{chunk_size} bytes. Binary length: #{byte_size(binary)} bytes.\n"
+              "Invalid binary length while decoding collection. \nInner type size: #{chunk_size} bytes. Binary length: #{byte_size(binary)} bytes."
           }}
          | results
        ]
@@ -455,7 +460,7 @@ defmodule SszEx.Decode do
     case Enum.group_by(results, fn {_, {type, _}} -> type end, fn {key, {_, result}} ->
            {key, result}
          end) do
-      %{error: errors} -> {:error, errors}
+      %{error: [first_error | _rest]} -> {:error, first_error}
       summary -> {:ok, Map.get(summary, :ok, [])}
     end
   end

lib/ssz_ex/encode.ex

@@ -55,7 +55,7 @@ defmodule SszEx.Encode do
       {:error,
        %Error{
          message:
-           "Invalid binary length while encoding list of #{inspect(inner_type)}.\nExpected max_size: #{max_size}.\nFound: #{size}\n"
+           "Invalid binary length while encoding list of #{inspect(inner_type)}.\nExpected max_size: #{max_size}.\nFound: #{size}"
        }}
     else
       list
@@ -71,7 +71,7 @@ defmodule SszEx.Encode do
       {:error,
        %Error{
          message:
-           "Invalid binary length while encoding BitList.\nExpected max_size: #{max_size}. Found: #{len}.\n"
+           "Invalid binary length while encoding BitList.\nExpected max_size: #{max_size}. Found: #{len}."
        }}
     else
       {:ok, BitList.to_bytes(bit_list)}
@@ -96,7 +96,7 @@ defmodule SszEx.Encode do
       {:error,
        %Error{
          message:
-           "Invalid binary length while encoding list of #{inspect(inner_type)}.\nExpected max_size: #{max_size}.\nFound: #{size}\n"
+           "Invalid binary length while encoding list of #{inspect(inner_type)}.\nExpected max_size: #{max_size}.\nFound: #{size}"
        }}
     else
       fixed_lengths = @bytes_per_length_offset * length(list)
@@ -147,8 +147,7 @@ defmodule SszEx.Encode do
            Enum.reduce(variable_parts, 0, fn part, acc -> byte_size(part) + acc end),
          :ok <- check_length(fixed_length, variable_length),
          {:ok, fixed_parts} <-
-           replace_offsets(fixed_size_values, offsets)
-           |> encode_schemas() do
+           replace_offsets(fixed_size_values, offsets) |> encode_schemas() do
       (fixed_parts ++ variable_parts)
       |> Enum.join()
       |> then(&{:ok, &1})
@@ -163,23 +162,25 @@ defmodule SszEx.Encode do
 
       if Utils.variable_size?(schema) do
         {[:offset | acc_fixed_size_values], @bytes_per_length_offset + acc_fixed_length,
-         [{value, schema} | acc_variable_values]}
+         [{value, key, schema} | acc_variable_values]}
       else
-        {[{value, schema} | acc_fixed_size_values],
+        {[{value, key, schema} | acc_fixed_size_values],
          acc_fixed_length + Utils.get_fixed_size(schema), acc_variable_values}
       end
     end)
   end
 
   defp encode_schemas(tuple_values) do
-    Enum.map(tuple_values, fn {value, schema} -> encode(value, schema) end)
+    Enum.map(tuple_values, fn {value, key, schema} ->
+      encode(value, schema) |> Error.add_trace(key)
+    end)
     |> Utils.flatten_results()
   end
 
   defp calculate_offsets(variable_parts, fixed_length) do
     {offsets, _} =
       Enum.reduce(variable_parts, {[], fixed_length}, fn element, {res, acc} ->
-        {[{acc, {:int, 32}} | res], byte_size(element) + acc}
+        {[{acc, :offset, {:int, 32}} | res], byte_size(element) + acc}
       end)
 
     offsets

lib/ssz_ex/error.ex

@@ -3,13 +3,52 @@ defmodule SszEx.Error do
   Error messages for SszEx domain.
   """
   alias SszEx.Error
-  defstruct [:message]
-  @type t :: %__MODULE__{message: String.t()}
+  defstruct [:message, stacktrace: []]
+  @type t :: %__MODULE__{message: String.t(), stacktrace: list()}
 
-  def format(%Error{message: message}) do
-    "#{message}"
+  def format(%Error{message: message, stacktrace: []}), do: "#{message}\n"
+
+  def format(%Error{message: message, stacktrace: stacktrace}) do
+    formatted_stacktrace = stacktrace |> Enum.join(".")
+    "#{message}\nStacktrace: #{formatted_stacktrace}"
+  end
+
+  def add_container(%Error{message: message, stacktrace: stacktrace}, value)
+      when is_struct(value) do
+    new_trace =
+      value.__struct__ |> Module.split() |> List.last()
+
+    %Error{message: message, stacktrace: [new_trace | stacktrace]}
+  end
+
+  def add_container(%Error{} = error, :bool), do: error
+
+  def add_container(%Error{message: message, stacktrace: stacktrace}, value)
+      when is_atom(value) do
+    new_trace =
+      value |> Module.split() |> List.last()
+
+    %Error{message: message, stacktrace: [new_trace | stacktrace]}
   end
 
+  def add_container(%Error{message: message, stacktrace: stacktrace}, new_trace) do
+    %Error{message: message, stacktrace: [new_trace | stacktrace]}
+  end
+
+  def add_container({:error, %Error{} = error}, new_trace),
+    do: {:error, Error.add_container(error, new_trace)}
+
+  def add_container(value, _module), do: value
+
+  def add_trace(%Error{message: message, stacktrace: stacktrace}, new_trace) do
+    %Error{message: message, stacktrace: [new_trace | stacktrace]}
+  end
+
+  def add_trace({:error, %Error{} = error}, new_trace),
+    do: {:error, Error.add_trace(error, new_trace)}
+
+  def add_trace(value, _module), do: value
+
   defimpl String.Chars, for: __MODULE__ do
     def to_string(error), do: Error.format(error)
   end

lib/ssz_ex/merkleization.ex

@@ -39,6 +39,14 @@ defmodule SszEx.Merkleization do
 
   @spec hash_tree_root(binary, {:byte_vector, non_neg_integer}) ::
           {:ok, Types.root()}
+  def hash_tree_root(value, {:byte_vector, size}) when byte_size(value) != size,
+    do:
+      {:error,
+       %Error{
+         message:
+           "Invalid binary length while merkleizing byte_vector.\nExpected size: #{size}.\nFound: #{byte_size(value)}"
+       }}
+
   def hash_tree_root(value, {:byte_vector, _size}) do
     packed_chunks = pack_bytes(value)
     leaf_count = packed_chunks |> get_chunks_len() |> next_pow_of_two()
@@ -73,7 +81,7 @@ defmodule SszEx.Merkleization do
         {:error,
          %Error{
            message:
-             "Invalid binary length while merkleizing list of #{inspect(type)}.\nExpected max_size: #{max_size}.\nFound: #{len}\n"
+             "Invalid binary length while merkleizing list of #{inspect(type)}.\nExpected max_size: #{max_size}.\nFound: #{len}"
          }}
 
       Utils.basic_type?(type) ->
@@ -91,7 +99,7 @@ defmodule SszEx.Merkleization do
       {:error,
        %Error{
          message:
-           "Invalid binary length while merkleizing vector of #{inspect(inner_type)}.\nExpected size: #{size}.\nFound: #{length(vector)}\n"
+           "Invalid binary length while merkleizing vector of #{inspect(inner_type)}.\nExpected size: #{size}.\nFound: #{length(vector)}"
        }}
 
   def hash_tree_root(vector, {:vector, type, _size} = schema) do
@@ -118,7 +126,7 @@ defmodule SszEx.Merkleization do
 
         case hash_tree_root(value, schema) do
           {:ok, root} -> {:cont, {:ok, acc_root <> root}}
-          {:error, %Error{}} = error -> {:halt, error}
+          {:error, %Error{} = error} -> {:halt, {:error, Error.add_trace(error, key)}}
         end
       end)
 

lib/ssz_ex/ssz_ex.ex

@@ -62,12 +62,17 @@ defmodule SszEx do
 
   @spec encode(struct()) ::
           {:ok, binary()} | {:error, Error.t()}
-  def encode(%name{} = value), do: encode(value, name)
+  def encode(%name{} = value), do: encode(value, name) |> Error.add_container(value)
 
   @spec encode(any(), schema()) ::
           {:ok, binary()} | {:error, Error.t()}
   def encode(value, schema), do: Encode.encode(value, schema)
 
+  @spec decode(binary(), schema()) ::
+          {:ok, any()} | {:error, Error.t()}
+  def decode(value, module) when is_atom(module),
+    do: Decode.decode(value, module) |> Error.add_container(module)
+
   @spec decode(binary(), schema()) ::
           {:ok, any()} | {:error, Error.t()}
   def decode(value, schema), do: Decode.decode(value, schema)
@@ -78,6 +83,10 @@ defmodule SszEx do
   @spec hash_tree_root!(any, any) :: Types.root()
   def hash_tree_root!(value, schema), do: Merkleization.hash_tree_root!(value, schema)
 
+  @spec hash_tree_root(struct()) :: {:ok, Types.root()} | {:error, Error.t()}
+  def hash_tree_root(%name{} = value),
+    do: hash_tree_root(value, name) |> Error.add_container(value)
+
   @spec hash_tree_root(any, any) :: {:ok, Types.root()} | {:error, Error.t()}
   def hash_tree_root(value, schema), do: Merkleization.hash_tree_root(value, schema)
 

lib/ssz_ex/utils.ex

@@ -67,7 +67,7 @@ defmodule SszEx.Utils do
 
   def flatten_results_by(results, fun) do
     case Enum.group_by(results, fn {type, _} -> type end, fn {_, result} -> result end) do
-      %{error: errors} -> {:error, errors}
+      %{error: [first_error | _rest]} -> {:error, first_error}
       summary -> {:ok, fun.(Map.get(summary, :ok, []))}
     end
   end