add find_contructor_arguments

apps/explorer/lib/explorer/smart_contract/verifier/constructor_arguments.ex

@@ -2,7 +2,7 @@ defmodule Explorer.SmartContract.Verifier.ConstructorArguments do
   @moduledoc """
   Smart contract contrstructor arguments verification logic.
   """
-
+  alias ABI.{FunctionSelector, TypeDecoder}
   alias Explorer.Chain
 
   def verify(address_hash, contract_code, arguments_data) do
@@ -15,7 +15,7 @@ defmodule Explorer.SmartContract.Verifier.ConstructorArguments do
 
     check_func = fn assumed_arguments -> assumed_arguments == arguments_data end
 
-    if verify_older_version(creation_code, contract_code, arguments_data) do
+    if verify_older_version(creation_code, contract_code, check_func) do
       true
     else
       extract_constructor_arguments(creation_code, check_func)
@@ -24,11 +24,11 @@ defmodule Explorer.SmartContract.Verifier.ConstructorArguments do
 
   # Earlier versions of Solidity didn't have whisper code.
   # constructor argument were directly appended to source code
-  defp verify_older_version(creation_code, contract_code, arguments_data) do
+  defp verify_older_version(creation_code, contract_code, check_func) do
     creation_code
     |> String.split(contract_code)
     |> List.last()
-    |> Kernel.==(arguments_data)
+    |> check_func.()
   end
 
   defp extract_constructor_arguments(code, check_func) do
@@ -74,18 +74,30 @@ defmodule Explorer.SmartContract.Verifier.ConstructorArguments do
     end
   end
 
-  # def find_contructor_arguments(address_hash, contract_code, abi) do
+  def find_contructor_arguments(address_hash, contract_code, abi) do
-  #   arguments_data = arguments_data |> String.trim_trailing() |> String.trim_leading("0x")
+    creation_code =
+      address_hash
+      |> Chain.contract_creation_input_data()
+      |> String.replace("0x", "")
+
+    constructor_abi = Enum.find(abi, fn el -> el["type"] == "constructor" && el["inputs"] != [] end)
 
-  #   creation_code =
+    input_types = Enum.map(constructor_abi["inputs"], &FunctionSelector.parse_specification_type/1)
-  #     address_hash
-  #     |> Chain.contract_creation_input_data()
-  #     |> String.replace("0x", "")
 
-  #   if verify_older_version(creation_code, contract_code, arguments_data) do
+    check_func = fn assumed_arguments ->
-  #     true
+      try do
-  #   else
+        _ =
-  #     extract_constructor_arguments(creation_code, arguments_data)
+          assumed_arguments
-  #   end
+          |> Base.decode16!(case: :mixed)
-  # end
+          |> TypeDecoder.decode_raw(input_types)
+
+        assumed_arguments
+      rescue
+        _ -> false
+      end
+    end
+
+    verify_older_version(creation_code, contract_code, check_func) ||
+      extract_constructor_arguments(creation_code, check_func)
+  end
 end

apps/explorer/test/explorer/smart_contract/verifier/constructor_arguments_test.exs

@@ -6,6 +6,7 @@ defmodule Explorer.SmartContract.Verifier.ConstructorArgumentsTest do
   alias Explorer.Chain.Data
   alias Explorer.SmartContract.Verifier.ConstructorArguments
 
+  describe "verify/3" do
     test "veriies constructor constructor arguments with whisper data" do
       constructor_arguments = Base.encode16(:crypto.strong_rand_bytes(64), case: :lower)
       address = insert(:address)
@@ -66,3 +67,25 @@ defmodule Explorer.SmartContract.Verifier.ConstructorArgumentsTest do
       assert ConstructorArguments.verify(address.hash, source_code, constructor_arguments)
     end
   end
+
+  describe "find_contructor_arguments/3" do
+    test "finds contructor arguments" do
+      address = insert(:address)
+      expected_contructor_arguments =
+        "000000000000000000000000314159265dd8dbb310642f98f50c066173c1259b93cdeb708b7545dc668eb9280176169d1c33cfd8ed6f04690a0bcc88a93fc4ae00000000000000000000000000000000000000000000000000000000590b09b0"
+
+      input =
+        "a165627a7a72305820fbfa6f8a2024760ef0e0eb29a332c9a820526e92f8b4fbcce6f00c7643234b1400297b6c4b278d165a6b33958f8ea5dfb00c8c9d4d0acf1985bef5d10786898bc3e7a165627a7a723058203c2db82e7c80cd1e371fe349b03d49b812c324ba4a3fcd063b7bc2662353c5de0029000000000000000000000000314159265dd8dbb310642f98f50c066173c1259b93cdeb708b7545dc668eb9280176169d1c33cfd8ed6f04690a0bcc88a93fc4ae00000000000000000000000000000000000000000000000000000000590b09b0"
+
+      input_data = %Data{
+        bytes: Base.decode16!(input, case: :lower)
+      }
+
+      :transaction
+      |> insert(created_contract_address_hash: address.hash, input: input_data)
+      |> with_block()
+
+      assert ConstructorArguments.find_contructor_arguments(address.hash, "", %{})
+    end
+  end
+end