Fix contract constructor require msg appearance in constructor arguments encoded view

CHANGELOG.md

@@ -6,6 +6,7 @@
 - [#2918](https://github.com/poanetwork/blockscout/pull/2918) - Add tokenID for tokentx API action explicitly
 
 ### Fixes
+- [#2969](https://github.com/poanetwork/blockscout/pull/2969) - Fix contract constructor require msg appearance in constructor arguments encoded view
 - [#2964](https://github.com/poanetwork/blockscout/pull/2964) - Fix bug in skipping of constructor arguments in contract verification
 - [#2961](https://github.com/poanetwork/blockscout/pull/2961) - Add a guard that addresses is enum in `values` function in `read contract` page
 - [#2960](https://github.com/poanetwork/blockscout/pull/2960) - Add BLOCKSCOUT_HOST to docker setup

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

@@ -54,18 +54,25 @@ defmodule Explorer.SmartContract.Verifier do
         external_libs: external_libraries
       )
 
-    compare_bytecodes(solc_output, address_hash, constructor_arguments, autodetect_contructor_arguments)
+    compare_bytecodes(
+      solc_output,
+      address_hash,
+      constructor_arguments,
+      autodetect_contructor_arguments,
+      contract_source_code
+    )
   end
 
-  defp compare_bytecodes({:error, :name}, _, _, _), do: {:error, :name}
-  defp compare_bytecodes({:error, _}, _, _, _), do: {:error, :compilation}
+  defp compare_bytecodes({:error, :name}, _, _, _, _), do: {:error, :name}
+  defp compare_bytecodes({:error, _}, _, _, _, _), do: {:error, :compilation}
 
   # credo:disable-for-next-line /Complexity/
   defp compare_bytecodes(
          {:ok, %{"abi" => abi, "bytecode" => bytecode}},
          address_hash,
          arguments_data,
-         autodetect_contructor_arguments
+         autodetect_contructor_arguments,
+         contract_source_code
        ) do
     generated_bytecode = extract_bytecode(bytecode)
 
@@ -82,7 +89,7 @@ defmodule Explorer.SmartContract.Verifier do
         {:error, :generated_bytecode}
 
       has_constructor_with_params?(abi) && autodetect_contructor_arguments ->
-        result = ConstructorArguments.find_constructor_arguments(address_hash, abi)
+        result = ConstructorArguments.find_constructor_arguments(address_hash, abi, contract_source_code)
 
         if result do
           {:ok, %{abi: abi, contructor_arguments: result}}
@@ -94,7 +101,12 @@ defmodule Explorer.SmartContract.Verifier do
         {:error, :constructor_arguments}
 
       has_constructor_with_params?(abi) &&
-          !ConstructorArguments.verify(address_hash, blockchain_bytecode_without_whisper, arguments_data) ->
+          !ConstructorArguments.verify(
+            address_hash,
+            blockchain_bytecode_without_whisper,
+            arguments_data,
+            contract_source_code
+          ) ->
         {:error, :constructor_arguments}
 
       true ->

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

@@ -5,7 +5,7 @@ defmodule Explorer.SmartContract.Verifier.ConstructorArguments do
   alias ABI.{FunctionSelector, TypeDecoder}
   alias Explorer.Chain
 
-  def verify(address_hash, contract_code, arguments_data) do
+  def verify(address_hash, contract_code, arguments_data, contract_source_code) do
     arguments_data = arguments_data |> String.trim_trailing() |> String.trim_leading("0x")
 
     creation_code =
@@ -18,7 +18,7 @@ defmodule Explorer.SmartContract.Verifier.ConstructorArguments do
     if verify_older_version(creation_code, contract_code, check_func) do
       true
     else
-      extract_constructor_arguments(creation_code, check_func)
+      extract_constructor_arguments(creation_code, check_func, contract_source_code)
     end
   end
 
@@ -31,22 +31,22 @@ defmodule Explorer.SmartContract.Verifier.ConstructorArguments do
     |> check_func.()
   end
 
-  defp extract_constructor_arguments(code, check_func) do
+  defp extract_constructor_arguments(code, check_func, contract_source_code) do
     case code do
       # Solidity ~ 4.23 # https://solidity.readthedocs.io/en/v0.4.23/metadata.html
       "a165627a7a72305820" <> <<_::binary-size(64)>> <> "0029" <> constructor_arguments ->
-        extract_constructor_arguments_check_func(constructor_arguments, check_func)
+        extract_constructor_arguments_check_func(constructor_arguments, check_func, contract_source_code)
 
       # Solidity >= 0.5.10 https://solidity.readthedocs.io/en/v0.5.10/metadata.html
       "a265627a7a72305820" <>
           <<_::binary-size(64)>> <> "64736f6c6343" <> <<_::binary-size(6)>> <> "0032" <> constructor_arguments ->
-        extract_constructor_arguments_check_func(constructor_arguments, check_func)
+        extract_constructor_arguments_check_func(constructor_arguments, check_func, contract_source_code)
 
       # Solidity >= 0.5.11 https://github.com/ethereum/solidity/blob/develop/Changelog.md#0511-2019-08-12
       # Metadata: Update the swarm hash to the current specification, changes bzzr0 to bzzr1 and urls to use bzz-raw://
       "a265627a7a72315820" <>
           <<_::binary-size(64)>> <> "64736f6c6343" <> <<_::binary-size(6)>> <> "0032" <> constructor_arguments ->
-        extract_constructor_arguments_check_func(constructor_arguments, check_func)
+        extract_constructor_arguments_check_func(constructor_arguments, check_func, contract_source_code)
 
       # Solidity >= 0.6.0 https://github.com/ethereum/solidity/blob/develop/Changelog.md#060-2019-12-17
       # https://github.com/ethereum/solidity/blob/26b700771e9cc9c956f0503a05de69a1be427963/docs/metadata.rst#encoding-of-the-metadata-hash-in-the-bytecode
@@ -60,27 +60,47 @@ defmodule Explorer.SmartContract.Verifier.ConstructorArguments do
       # Fixing PR has been created https://github.com/ethereum/solidity/pull/8174
       "a264697066735822" <>
           <<_::binary-size(68)>> <> "64736f6c6343" <> <<_::binary-size(6)>> <> "0033" <> constructor_arguments ->
-        extract_constructor_arguments_check_func(constructor_arguments, check_func)
+        extract_constructor_arguments_check_func(constructor_arguments, check_func, contract_source_code)
 
       <<>> ->
         check_func.("")
 
       <<_::binary-size(2)>> <> rest ->
-        extract_constructor_arguments(rest, check_func)
+        extract_constructor_arguments(rest, check_func, contract_source_code)
     end
   end
 
-  defp extract_constructor_arguments_check_func(constructor_arguments, check_func) do
+  defp extract_constructor_arguments_check_func(constructor_arguments, check_func, contract_source_code) do
+    constructor_arguments =
+      remove_require_messages_from_constructor_arguments(contract_source_code, constructor_arguments)
+
     check_func_result = check_func.(constructor_arguments)
 
     if check_func_result do
       check_func_result
     else
-      extract_constructor_arguments(constructor_arguments, check_func)
+      extract_constructor_arguments(constructor_arguments, check_func, contract_source_code)
     end
   end
 
-  def find_constructor_arguments(address_hash, abi) do
+  def remove_require_messages_from_constructor_arguments(contract_source_code, constructor_arguments) do
+    msgs_list =
+      contract_source_code
+      |> extract_require_messages_from_constructor()
+      |> Enum.reverse()
+
+    Enum.reduce(msgs_list, constructor_arguments, fn msg, pure_constructor_arguments ->
+      case String.split(pure_constructor_arguments, msg, parts: 2) do
+        [_, constructor_arguments_part] ->
+          constructor_arguments_part
+
+        [_] ->
+          pure_constructor_arguments
+      end
+    end)
+  end
+
+  def find_constructor_arguments(address_hash, abi, contract_source_code) do
     creation_code =
       address_hash
       |> Chain.contract_creation_input_data()
@@ -103,6 +123,61 @@ defmodule Explorer.SmartContract.Verifier.ConstructorArguments do
       end
     end
 
-    extract_constructor_arguments(creation_code, check_func)
+    extract_constructor_arguments(creation_code, check_func, contract_source_code)
+  end
+
+  def extract_require_messages_from_constructor(contract_source_code) do
+    constructor = find_constructor_content(contract_source_code)
+    require_contents = find_require_in_constructor(constructor)
+
+    messages_list =
+      Enum.reduce(require_contents, [], fn require_content, msgs ->
+        msg = get_require_message_hex(require_content)
+        if msg, do: [msg | msgs]
+      end)
+
+    if messages_list, do: messages_list, else: []
+  end
+
+  def find_constructor_content(contract_source_code) do
+    case String.split(contract_source_code, "constructor", parts: 2) do
+      [_, right_from_contstructor] ->
+        [_, right_from_contstructor_inside] = String.split(right_from_contstructor, "{", parts: 2)
+        [constructor, _] = String.split(right_from_contstructor_inside, "}", parts: 2)
+        constructor
+
+      [_] ->
+        nil
+    end
+  end
+
+  def find_require_in_constructor(constructor) do
+    if constructor do
+      [_ | requires] = String.split(constructor, "require")
+
+      Enum.reduce(requires, [], fn right_from_require, requires_list ->
+        [_ | [right_from_require_inside]] = String.split(right_from_require, "(", parts: 2)
+        [require_content | _] = String.split(right_from_require_inside, ");", parts: 2)
+        [require_content | requires_list]
+      end)
+    else
+      []
+    end
+  end
+
+  def get_require_message_hex(require_content) do
+    case String.split(require_content, ",", parts: 2) do
+      [_ | [msg]] ->
+        msg
+        |> String.trim()
+        |> String.trim_leading("\"")
+        |> String.trim_trailing("\"")
+        |> String.trim_leading("'")
+        |> String.trim_trailing("'")
+        |> Base.encode16(case: :lower)
+
+      [_] ->
+        nil
+    end
   end
 end