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make NewFunc return struct instead of interface.
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- new w3.Func implements core.Func
- w3.Func exports fields "Signature", "Selector", "Args", and "Returns"
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@lmittmann
lmittmann committed Jan 23, 2022
1 parent 49980d1 commit cfdc773
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Showing 3 changed files with 85 additions and 38 deletions.
2 changes: 1 addition & 1 deletion core/interfaces.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,7 @@ import "github.com/ethereum/go-ethereum/rpc"
// Func is the interface that wraps the methods for ABI encoding and decoding.
type Func interface {

// EncodeArgs ABI-encodes the given args and prepends the Func's four-byte
// EncodeArgs ABI-encodes the given args and prepends the Func's 4-byte
// selector.
EncodeArgs(args ...interface{}) (input []byte, err error)

Expand Down
71 changes: 39 additions & 32 deletions func.go
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Original file line number Diff line number Diff line change
Expand Up @@ -6,10 +6,9 @@ import (
"fmt"
"reflect"

_abi "github.com/ethereum/go-ethereum/accounts/abi"
"github.com/ethereum/go-ethereum/accounts/abi"
"github.com/ethereum/go-ethereum/crypto"
"github.com/lmittmann/w3/core"
"github.com/lmittmann/w3/internal/abi"
_abi "github.com/lmittmann/w3/internal/abi"
)

var (
Expand All @@ -19,61 +18,64 @@ var (
ErrInvalidType = errors.New("w3: invalid type")
ErrEvmRevert = errors.New("w3: evm reverted")

revertSelector = crypto.Keccak256([]byte("Error(string)"))[:4]
approveSelector = crypto.Keccak256([]byte("approve(address,uint256)"))[:4]
transferSelector = crypto.Keccak256([]byte("transfer(address,uint256)"))[:4]
transferFromSelector = crypto.Keccak256([]byte("transferFrom(address,address,uint256)"))[:4]
revertSelector = selector("Error(string)")
approveSelector = selector("approve(address,uint256)")
transferSelector = selector("transfer(address,uint256)")
transferFromSelector = selector("transferFrom(address,address,uint256)")
)

type abiFunc struct {
Signature string
Selector []byte // four-byte selector
Args _abi.Arguments // input
Returns _abi.Arguments // output
// Func represents a Smart Contract function ABI binding.
//
// Func implements the core.Func interface.
type Func struct {
Signature string // Function signature
Selector [4]byte // 4-byte selector
Args abi.Arguments // Input arguments
Returns abi.Arguments // Output returns
}

// NewFunc returns a new Smart Contract function ABI binding from the given
// Solidity function signature and its returns.
//
// An error is returned if the signature or returns parsing fails.
func NewFunc(signature, returns string) (core.Func, error) {
args, err := abi.Parse(signature)
func NewFunc(signature, returns string) (*Func, error) {
args, err := _abi.Parse(signature)
if err != nil {
return nil, fmt.Errorf("%w: %v", ErrInvalidABI, err)
}
if args.FuncName == "" {
return nil, fmt.Errorf("%w: missing function name", ErrInvalidABI)
}

returnArgs, err := abi.Parse(returns)
returnArgs, err := _abi.Parse(returns)
if err != nil {
return nil, fmt.Errorf("%w: %v", ErrInvalidABI, err)
}
if returnArgs.FuncName != "" {
return nil, fmt.Errorf("%w: returns must not have a function name", ErrInvalidABI)
}

return &abiFunc{
return &Func{
Signature: args.Sig,
Selector: crypto.Keccak256([]byte(args.Sig))[:4],
Selector: selector(args.Sig),
Args: args.Args,
Returns: returnArgs.Args,
}, nil
}

// MustNewFunc is like NewFunc but panics if the signature or returns parsing
// fails.
func MustNewFunc(signature, returns string) core.Func {
func MustNewFunc(signature, returns string) *Func {
fn, err := NewFunc(signature, returns)
if err != nil {
panic(err)
}
return fn
}

// EncodeArgs ABI-encodes the given args and prepends the Func's four-byte
// EncodeArgs ABI-encodes the given args and prepends the Func's 4-byte
// selector.
func (f *abiFunc) EncodeArgs(args ...interface{}) ([]byte, error) {
func (f *Func) EncodeArgs(args ...interface{}) ([]byte, error) {
if len(f.Args) != len(args) {
return nil, fmt.Errorf("%w: expected %d arguments, got %d", ErrArgumentMismatch, len(f.Args), len(args))
}
Expand All @@ -83,11 +85,11 @@ func (f *abiFunc) EncodeArgs(args ...interface{}) ([]byte, error) {
return nil, err
}

return append(f.Selector, input...), nil
return append(f.Selector[:], input...), nil
}

// DecodeArgs ABI-decodes the given input to the given args.
func (f *abiFunc) DecodeArgs(input []byte, args ...interface{}) error {
func (f *Func) DecodeArgs(input []byte, args ...interface{}) error {
if len(f.Args) != len(args) {
return fmt.Errorf("%w: expected %d arguments, got %d", ErrArgumentMismatch, len(f.Args), len(args))
}
Expand All @@ -106,28 +108,27 @@ func (f *abiFunc) DecodeArgs(input []byte, args ...interface{}) error {
}

// DecodeReturns ABI-decodes the given output to the given returns.
func (f *abiFunc) DecodeReturns(output []byte, returns ...interface{}) error {
func (f *Func) DecodeReturns(output []byte, returns ...interface{}) error {
if len(f.Returns) != len(returns) {
return fmt.Errorf("%w: expected %d returns, got %d", ErrReturnsMismatch, len(f.Returns), len(returns))
}

// check the output for a revert reason
if bytes.HasPrefix(output, revertSelector) {
if reason, err := _abi.UnpackRevert(output); err != nil {
if bytes.HasPrefix(output, revertSelector[:]) {
if reason, err := abi.UnpackRevert(output); err != nil {
return err
} else {
return fmt.Errorf("%w: %s", ErrEvmRevert, reason)
}
}

// Gracefully handle uncompliant ERC20 returns
if len(output) == 0 &&
(bytes.Equal(f.Selector, approveSelector) ||
bytes.Equal(f.Selector, transferSelector) ||
bytes.Equal(f.Selector, transferFromSelector)) &&
len(returns) == 1 {
if len(returns) == 1 && len(output) == 0 &&
(f.Selector == approveSelector ||
f.Selector == transferSelector ||
f.Selector == transferFromSelector) {

if err := copyVal(_abi.BoolTy, returns[0], true); err != nil {
if err := copyVal(abi.BoolTy, returns[0], true); err != nil {
return err
}
return nil
Expand Down Expand Up @@ -156,7 +157,7 @@ func copyVal(t byte, dst, src interface{}) (err error) {
rSrc := reflect.ValueOf(src)

switch t {
case _abi.TupleTy:
case abi.TupleTy:
err = copyTuple(rDst, rSrc)
default:
err = copyNonTuple(rDst, rSrc)
Expand Down Expand Up @@ -199,3 +200,9 @@ func copyTuple(rDst, rSrc reflect.Value) error {
}
return nil
}

// selector returns the 4-byte selector of the given signature.
func selector(signature string) (selector [4]byte) {
copy(selector[:], crypto.Keccak256([]byte(signature)))
return
}
50 changes: 45 additions & 5 deletions func_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -6,13 +6,53 @@ import (
"strconv"
"testing"

_abi "github.com/ethereum/go-ethereum/accounts/abi"
"github.com/ethereum/go-ethereum/accounts/abi"
"github.com/ethereum/go-ethereum/common"
"github.com/google/go-cmp/cmp"
"github.com/google/go-cmp/cmp/cmpopts"
"github.com/lmittmann/w3/core"
)

func TestNewFunc(t *testing.T) {
t.Parallel()

tests := []struct {
Signature string
Returns string
WantFunc *Func
}{
{
Signature: "transfer(address,uint256)",
Returns: "bool",
WantFunc: &Func{
Signature: "transfer(address,uint256)",
Selector: [4]byte{0xa9, 0x05, 0x9c, 0xbb},
},
},
{
Signature: "transfer(address recipient, uint256 amount)",
Returns: "bool success",
WantFunc: &Func{
Signature: "transfer(address,uint256)",
Selector: [4]byte{0xa9, 0x05, 0x9c, 0xbb},
},
},
}

for i, test := range tests {
t.Run(strconv.Itoa(i), func(t *testing.T) {
gotFunc, err := NewFunc(test.Signature, test.Returns)
if err != nil {
t.Fatalf("Failed to create new FUnc: %v", err)
}

if diff := cmp.Diff(test.WantFunc, gotFunc, cmpopts.IgnoreFields(Func{}, "Args", "Returns")); diff != "" {
t.Fatalf("(-want, +got)\n%s", diff)
}
})
}
}

func TestEncodeArgs(t *testing.T) {
t.Parallel()

Expand Down Expand Up @@ -242,23 +282,23 @@ func TestCopyValue(t *testing.T) {
WantErr error
}{
{
T: _abi.UintTy,
T: abi.UintTy,
Dst: new(big.Int),
Src: big.NewInt(42),
},
{
T: _abi.UintTy,
T: abi.UintTy,
Dst: new(big.Int),
Src: big.NewInt(42),
},
{
T: _abi.UintTy,
T: abi.UintTy,
Dst: new(big.Int),
Src: []byte{1, 2, 3},
WantErr: ErrInvalidType,
},
{
T: _abi.BytesTy,
T: abi.BytesTy,
Dst: &[]byte{},
Src: &[]byte{1, 2, 3},
},
Expand Down

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