EVM parsing functions with ABI

api/logic/evm.go

@@ -0,0 +1,40 @@
+package logic
+
+import (
+	"fmt"
+
+	"github.com/ethereum/go-ethereum/accounts/abi"
+	ethCommon "github.com/ethereum/go-ethereum/common"
+)
+
+func EVMParseData(data []byte, contractABI *abi.ABI) (*abi.Method, []interface{}, error) {
+	if len(data) < 4 {
+		return nil, nil, fmt.Errorf("data (%dB) too short to have method ID", len(data))
+	}
+	methodID := data[:4]
+	packedArgs := data[4:]
+	method, err := contractABI.MethodById(methodID)
+	if err != nil {
+		return nil, nil, fmt.Errorf("contract ABI MethodById: %w", err)
+	}
+	args, err := method.Inputs.Unpack(packedArgs)
+	if err != nil {
+		return nil, nil, fmt.Errorf("method inputs Unpack: %w", err)
+	}
+	return method, args, nil
+}
+
+func EVMParseEvent(topics [][]byte, data []byte, contractABI *abi.ABI) (*abi.Event, []interface{}, error) {
+	if len(topics) < 1 {
+		return nil, nil, fmt.Errorf("topics (%d) too short to have event signature", len(topics))
+	}
+	event, err := contractABI.EventByID(ethCommon.BytesToHash(topics[0]))
+	if err != nil {
+		return nil, nil, fmt.Errorf("contract ABI EventByID: %w", err)
+	}
+	args, err := event.Inputs.Unpack(data)
+	if err != nil {
+		return nil, nil, fmt.Errorf("event inputs Unpack: %w", err)
+	}
+	return event, args, nil
+}

api/logic/evm_test.go

@@ -0,0 +1,47 @@
+package logic
+
+import (
+	"encoding/hex"
+	"math/big"
+	"testing"
+
+	ethCommon "github.com/ethereum/go-ethereum/common"
+	"github.com/stretchr/testify/require"
+
+	"github.com/oasisprotocol/nexus/analyzer/evmabi"
+)
+
+func TestEVMParseData(t *testing.T) {
+	// https://explorer.emerald.oasis.dev/tx/0x1ac7521df4cda38c87cff56b1311ee9362168bd794230415a37f2aff3a554a5f/internal-transactions
+	data, err := hex.DecodeString("095ea7b3000000000000000000000000250d48c5e78f1e85f7ab07fec61e93ba703ae6680000000000000000000000000000000000000000000000003782dace9d900000")
+	require.NoError(t, err)
+	method, args, err := EVMParseData(data, evmabi.ERC20)
+	require.NoError(t, err)
+	require.Equal(t, evmabi.ERC20.Methods["approve"], *method)
+	require.Equal(t, []interface{}{
+		ethCommon.HexToAddress("0x250d48c5e78f1e85f7ab07fec61e93ba703ae668"),
+		big.NewInt(4000000000000000000),
+	}, args)
+}
+
+func TestEVMParseEvent(t *testing.T) {
+	// https://explorer.emerald.oasis.dev/tx/0x1ac7521df4cda38c87cff56b1311ee9362168bd794230415a37f2aff3a554a5f/logs
+	topicsHex := []string{
+		"8c5be1e5ebec7d5bd14f71427d1e84f3dd0314c0f7b2291e5b200ac8c7c3b925",
+		"0000000000000000000000000ecf5262e5b864e1612875f8fc18f151315b5e91",
+		"000000000000000000000000250d48c5e78f1e85f7ab07fec61e93ba703ae668",
+	}
+	var topics [][]byte
+	for _, topicHex := range topicsHex {
+		topic, err := hex.DecodeString(topicHex)
+		require.NoError(t, err)
+		topics = append(topics, topic)
+	}
+	data, err := hex.DecodeString("0000000000000000000000000000000000000000000000003782dace9d900000")
+	require.NoError(t, err)
+	event, args, err := EVMParseEvent(topics, data, evmabi.ERC20)
+	require.Equal(t, evmabi.ERC20.Events["Approval"], *event)
+	require.Equal(t, []interface{}{
+		big.NewInt(4000000000000000000),
+	}, args)
+}