[investigate] ABI

gnovm/stdlibs/abi/encoder.go

@@ -0,0 +1,155 @@
+package abi
+
+import (
+	"crypto/sha256"
+	"encoding/binary"
+	"fmt"
+	"math/big"
+	"strings"
+)
+
+// EncodeFunction encodes a function call with the given signature and parameters into an ABI encoding.
+func EncodeFunction(signature string, params ...interface{}) ([]byte, error) {
+	funcName, paramTypes, err := parseSignature(signature)
+	if err != nil {
+		return nil, err
+	}
+
+	if len(paramTypes) != len(params) {
+		return nil, fmt.Errorf("number of parameters does not match the signature")
+	}
+
+	encodedParams := make([]byte, 0)
+	for i, paramType := range paramTypes {
+		param := params[i]
+		encodedParam, err := encodeParameter(paramType, param)
+		if err != nil {
+			return nil, err
+		}
+		encodedParams = append(encodedParams, encodedParam...)
+	}
+
+	selector := calculateFunctionSelector(funcName, paramTypes)
+	abiEncoding := append(selector, encodedParams...)
+
+	return abiEncoding, nil
+}
+
+// parseSignature parses a function signature and returns the function name and parameter types.
+func parseSignature(signature string) (string, []string, error) {
+	// validate function signature format
+	if !strings.Contains(signature, "(") || !strings.Contains(signature, ")") {
+		return "", nil, fmt.Errorf("invalid function signature")
+	}
+
+	// split the function name and param parts
+	parts := strings.Split(signature, "(")
+	funcName := parts[0]
+	paramsString := strings.TrimSuffix(parts[1], ")")
+
+	// extract param type
+	paramTypes := make([]string, 0)
+	if paramsString != "" {
+		paramTypes = strings.Split(paramsString, ",")
+		for i := range paramTypes {
+			paramTypes[i] = strings.TrimSpace(paramTypes[i])
+		}
+	}
+
+	return funcName, paramTypes, nil
+}
+
+// encodeParameter encodes a parameter value based on its type.
+func encodeParameter(paramType string, param interface{}) ([]byte, error) {
+	switch paramType {
+	case "uint256":
+		num, ok := param.(*big.Int) // TODO: remove bigInt
+		if !ok {
+			return nil, fmt.Errorf("invalid parameter type for uint256")
+		}
+		return encodeUint256(num), nil
+
+	case "address": // std.Address
+		addr, ok := param.([]byte)
+		if !ok || len(addr) != 20 {
+			return nil, fmt.Errorf("invalid parameter type for address")
+		}
+		return encodeAddress(addr), nil
+
+	case "bool":
+		b, ok := param.(bool)
+		if !ok {
+			return nil, fmt.Errorf("invalid parameter type for bool")
+		}
+		return encodeBool(b), nil
+
+	case "string":
+		str, ok := param.(string)
+		if !ok {
+			return nil, fmt.Errorf("invalid parameter type for string")
+		}
+		return encodeString(str), nil
+
+	// TODO: add more types
+
+	default:
+		return nil, fmt.Errorf("unsupported parameter type: %s", paramType)
+	}
+}
+
+// encodeUint256 encodes a uint256 value into a 32-byte big-endian byte slice.
+func encodeUint256(num *big.Int) []byte {
+	bytes := make([]byte, 32)
+	num.FillBytes(bytes)
+
+	return bytes
+}
+
+// encodeAddress encodes an address value into a 32-byte byte slice.
+func encodeAddress(addr []byte) []byte {
+	bytes := make([]byte, 32)
+	copy(bytes[12:], addr)
+
+	return bytes
+}
+
+// encodeBool encodes a boolean value into a 32-byte byte slice.
+func encodeBool(b bool) []byte {
+	bytes := make([]byte, 32)
+	if b {
+		bytes[31] = 1
+	}
+
+	return bytes
+}
+
+// encodeString encodes a string value into a byte slice with a 32-byte length prefix.
+func encodeString(str string) []byte {
+	strBytes := []byte(str)
+	lenBytes := make([]byte, 32)
+	binary.BigEndian.PutUint64(lenBytes[24:], uint64(len(strBytes)))
+	return append(lenBytes, strBytes...)
+}
+
+// calculateFunctionSelector calculates the function selector based on the function name and parameter types.
+func calculateFunctionSelector(funcName string, paramTypes []string) []byte {
+	var builder strings.Builder
+
+	builder.WriteString(funcName)
+	builder.WriteString("(")
+
+	for i, paramType := range paramTypes {
+		builder.WriteString(paramType)
+		if i < len(paramTypes)-1 {
+			builder.WriteString(",")
+		}
+	}
+
+	builder.WriteString(")")
+	signature := builder.String()
+
+	hash := sha256.Sum256([]byte(signature))
+	selector := hash[:4]
+
+	return selector
+}

gnovm/stdlibs/abi/encoder_test.go

@@ -0,0 +1,65 @@
+package abi
+
+import (
+	"fmt"
+	"math/big"
+	"reflect"
+	"testing"
+)
+
+func TestEncodeFunction(t *testing.T) {
+	t.Parallel()
+
+	num1 := big.NewInt(10)
+	num2 := big.NewInt(20)
+	expected := "ec2d2fd3000000000000000000000000000000000000000000000000000000000000000a0000000000000000000000000000000000000000000000000000000000000014"
+
+	res, err := EncodeFunction("add(uint256,uint256)", num1, num2)
+	if err != nil {
+		t.Errorf("EncodeFunction returned an error: %v", err)
+	}
+	if fmt.Sprintf("%x", res) != expected {
+		t.Errorf("EncodeFunction returned %x, expected %s", res, expected)
+	}
+}
+
+func TestParseSignature(t *testing.T) {
+	t.Parallel()
+
+	funcName, paramTypes, err := parseSignature("add(uint256,uint256)")
+	if err != nil {
+		t.Errorf("parseSignature returned an error: %v", err)
+	}
+	if funcName != "add" {
+		t.Errorf("parseSignature returned function name %s, expected 'add'", funcName)
+	}
+	if !reflect.DeepEqual(paramTypes, []string{"uint256", "uint256"}) {
+		t.Errorf("parseSignature returned parameter types %v, expected ['uint256', 'uint256']", paramTypes)
+	}
+}
+
+func TestEncodeParameter(t *testing.T) {
+	t.Parallel()
+
+	num := big.NewInt(10)
+	expected := []byte{0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0xa}
+
+	res, err := encodeParameter("uint256", num)
+	if err != nil {
+		t.Errorf("encodeParameter returned an error: %v", err)
+	}
+	if !reflect.DeepEqual(res, expected) {
+		t.Errorf("encodeParameter returned %x, expected %x", res, expected)
+	}
+}
+
+func TestCalculateFunctionSelector(t *testing.T) {
+	t.Parallel()
+
+	expected := []byte{0x9a, 0x2c, 0xd6, 0x1f}
+
+	res := calculateFunctionSelector("add", []string{"uint256", "uint256"})
+	if !reflect.DeepEqual(res, expected) {
+		t.Errorf("calculateFunctionSelector returned %x, expected %x", res, expected)
+	}
+}