feat(ssz): add support for transactions (lambdaclass#223)

lib/ssz.ex

@@ -9,9 +9,7 @@ defmodule Ssz do
   def to_ssz(map, config \\ MainnetConfig)
 
   def to_ssz(%name{} = map, config) do
-    map
-    |> encode()
-    |> to_ssz_rs(name, config)
+    to_ssz_typed(map, name, config)
   end
 
   def to_ssz([], config) do
@@ -20,9 +18,14 @@ defmodule Ssz do
   end
 
   def to_ssz([%name{} | _tail] = list, config) do
-    list
+    to_ssz_typed(list, name, config)
+  end
+
+  @spec to_ssz_typed(term, module, module) :: {:ok, binary} | {:error, String.t()}
+  def to_ssz_typed(term, schema, config \\ MainnetConfig) do
+    term
     |> encode()
-    |> to_ssz_rs(name, config)
+    |> to_ssz_rs(schema, config)
   end
 
   @spec from_ssz(binary, module, module) :: {:ok, struct} | {:error, String.t()}
@@ -50,17 +53,23 @@ defmodule Ssz do
 
   @spec hash_list_tree_root(list(struct), integer, module) ::
           {:ok, SszTypes.root()} | {:error, String.t()}
-  def hash_list_tree_root(map, max_size, config \\ MainnetConfig)
+  def hash_list_tree_root(list, max_size, config \\ MainnetConfig)
 
   def hash_list_tree_root([], max_size, config) do
     # Type isn't used in this case
     hash_tree_root_list_rs([], max_size, SszTypes.ForkData, config)
   end
 
   def hash_list_tree_root([%name{} | _tail] = list, max_size, config) do
+    hash_list_tree_root_typed(list, max_size, name, config)
+  end
+
+  @spec hash_list_tree_root_typed(list(struct), integer, module, module) ::
+          {:ok, binary} | {:error, String.t()}
+  def hash_list_tree_root_typed(list, max_size, schema, config \\ MainnetConfig) do
     list
     |> encode()
-    |> hash_tree_root_list_rs(max_size, name, config)
+    |> hash_tree_root_list_rs(max_size, schema, config)
   end
 
   ##### Rust-side function stubs

lib/ssz_types/transaction.ex

@@ -0,0 +1,5 @@
+defmodule SszTypes.Transaction do
+  @moduledoc """
+  Alias for `SszTypes.transaction`. Is used when explicit typing is needed.
+  """
+end

native/ssz_nif/src/elx_types/mod.rs

@@ -37,7 +37,7 @@ type BLSPubkey<'a> = Bytes48<'a>;
 type BLSSignature<'a> = Bytes96<'a>;
 #[allow(dead_code)]
 type ParticipationFlags = u8;
-type Transaction<'a> = Binary<'a>; // max size: 1073741824
+pub(crate) type Transaction<'a> = Binary<'a>; // max size: 1073741824
 type ExecutionAddress<'a> = Bytes20<'a>;
 type WithdrawalIndex = u64;
 

native/ssz_nif/src/ssz_types/mod.rs

@@ -38,7 +38,8 @@ type BLSPubkey = Bytes48;
 type BLSSignature = Bytes96;
 #[allow(dead_code)]
 type ParticipationFlags = u8;
-type Transaction = VariableList<u8, /* `MAX_BYTES_PER_TRANSACTION` */ typenum::U1073741824>;
+pub(crate) type Transaction =
+    VariableList<u8, /* `MAX_BYTES_PER_TRANSACTION` */ typenum::U1073741824>;
 type ExecutionAddress = Bytes20;
 type WithdrawalIndex = u64;
 

native/ssz_nif/src/utils/mod.rs

@@ -44,6 +44,7 @@ macro_rules! schema_match {
                 SignedAggregateAndProof<C>,
                 BeaconBlocksByRangeRequest,
                 BeaconBlocksByRangeResponse<C>,
+                Transaction,
             }
         )
     };

test/unit/ssz_test.exs

@@ -141,4 +141,29 @@ defmodule SSZTests do
     assert {:ok, ^deserialized} = Ssz.list_from_ssz(serialized, SszTypes.VoluntaryExit)
     assert {:ok, _hash} = Ssz.hash_list_tree_root(deserialized, 4)
   end
+
+  test "serialize and hash list of transactions" do
+    # These would be bytes
+    t1 = "asfasfas"
+    t2 = "18418280192"
+    t3 = "zd9g8as0f70a0sf"
+
+    deserialized = [t1, t2, t3]
+
+    initial_offset = length(deserialized) * 4
+
+    serialized =
+      Enum.join([
+        <<initial_offset::32-little>>,
+        <<initial_offset + byte_size(t1)::32-little>>,
+        <<initial_offset + byte_size(t1) + byte_size(t2)::32-little>>,
+        Enum.join(deserialized)
+      ])
+
+    assert {:ok, ^serialized} = Ssz.to_ssz_typed(deserialized, SszTypes.Transaction)
+    assert {:ok, ^deserialized} = Ssz.list_from_ssz(serialized, SszTypes.Transaction)
+
+    assert {:ok, _hash} =
+             Ssz.hash_list_tree_root_typed(deserialized, 1_048_576, SszTypes.Transaction)
+  end
 end