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Negative numbers not properly converted in ABI encoding #2653

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merged 1 commit into from
Jun 10, 2016
Merged

Negative numbers not properly converted in ABI encoding #2653

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2 changes: 1 addition & 1 deletion accounts/abi/method.go
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Original file line number Diff line number Diff line change
Expand Up @@ -62,7 +62,7 @@ func (m Method) pack(method Method, args ...interface{}) ([]byte, error) {
// calculate the offset
offset := len(method.Inputs)*32 + len(variableInput)
// set the offset
ret = append(ret, packNum(reflect.ValueOf(offset), UintTy)...)
ret = append(ret, packNum(reflect.ValueOf(offset))...)
// Append the packed output to the variable input. The variable input
// will be appended at the end of the input.
variableInput = append(variableInput, packed...)
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42 changes: 4 additions & 38 deletions accounts/abi/numbers.go
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Expand Up @@ -61,54 +61,20 @@ func U256(n *big.Int) []byte {
return common.LeftPadBytes(common.U256(n).Bytes(), 32)
}

func S256(n *big.Int) []byte {
sint := common.S256(n)
ret := common.LeftPadBytes(sint.Bytes(), 32)
if sint.Cmp(common.Big0) < 0 {
for i, b := range ret {
if b == 0 {
ret[i] = 1
continue
}
break
}
}

return ret
}

// S256 will ensure signed 256bit on big nums
func U2U256(n uint64) []byte {
return U256(big.NewInt(int64(n)))
}

func S2S256(n int64) []byte {
return S256(big.NewInt(n))
}

// packNum packs the given number (using the reflect value) and will cast it to appropriate number representation
func packNum(value reflect.Value, to byte) []byte {
func packNum(value reflect.Value) []byte {
switch kind := value.Kind(); kind {
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
if to == UintTy {
return U2U256(value.Uint())
} else {
return S2S256(int64(value.Uint()))
}
return U2U256(value.Uint())
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@karalabe karalabe Jun 9, 2016 •
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I think it would be cleaner to drop func U2U256(n uint64) altogether and just inline it here and below. Also it seems strange to me to go through an int64 for unsigned values (imho that's a bug, I'll check it with a test), so please use U256(new(big.Int).SetUint64(value.Uint())).

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@karalabe karalabe Jun 9, 2016 •
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Yup, the cast in both the original code and your code is wrong. My suggestion above fixes it. Please add this test to the testsuite for verification:

    maxuint64 := []byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 255, 255, 255, 255, 255, 255, 255, 255}

    packed := packNum(reflect.ValueOf(uint64(math.MaxUint64)))
    if !bytes.Equal(packed, maxuint64) {
        t.Errorf("expected %x got %x", maxuint64, packed)
    }

case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
if to == UintTy {
return U2U256(uint64(value.Int()))
} else {
return S2S256(value.Int())
}
return U2U256(uint64(value.Int()))
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Similar to the above comment, I would inline U256(big.NewInt(value.Int())) here. Seems cleaner and avoids the brain twist of casting to unsigned and back.

case reflect.Ptr:
// This only takes care of packing and casting. No type checking is done here. It should be done prior to using this function.
if to == UintTy {
return U256(value.Interface().(*big.Int))
} else {
return S256(value.Interface().(*big.Int))
}

return U256(value.Interface().(*big.Int))
}

return nil
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26 changes: 3 additions & 23 deletions accounts/abi/numbers_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -26,48 +26,28 @@ import (
func TestNumberTypes(t *testing.T) {
ubytes := make([]byte, 32)
ubytes[31] = 1
sbytesmin := []byte{1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1}

unsigned := U256(big.NewInt(1))
if !bytes.Equal(unsigned, ubytes) {
t.Errorf("expected %x got %x", ubytes, unsigned)
}

signed := S256(big.NewInt(1))
if !bytes.Equal(signed, ubytes) {
t.Errorf("expected %x got %x", ubytes, unsigned)
}

signed = S256(big.NewInt(-1))
if !bytes.Equal(signed, sbytesmin) {
t.Errorf("expected %x got %x", ubytes, unsigned)
}
}

func TestPackNumber(t *testing.T) {
ubytes := make([]byte, 32)
ubytes[31] = 1
sbytesmin := []byte{1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1}
maxunsigned := []byte{255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255}

packed := packNum(reflect.ValueOf(1), IntTy)
if !bytes.Equal(packed, ubytes) {
t.Errorf("expected %x got %x", ubytes, packed)
}
packed = packNum(reflect.ValueOf(-1), IntTy)
if !bytes.Equal(packed, sbytesmin) {
t.Errorf("expected %x got %x", ubytes, packed)
}
packed = packNum(reflect.ValueOf(1), UintTy)
packed := packNum(reflect.ValueOf(1))
if !bytes.Equal(packed, ubytes) {
t.Errorf("expected %x got %x", ubytes, packed)
}
packed = packNum(reflect.ValueOf(-1), UintTy)
packed = packNum(reflect.ValueOf(-1))
if !bytes.Equal(packed, maxunsigned) {
t.Errorf("expected %x got %x", maxunsigned, packed)
}

packed = packNum(reflect.ValueOf("string"), UintTy)
packed = packNum(reflect.ValueOf("string"))
if packed != nil {
t.Errorf("expected 'string' to pack to nil. got %x instead", packed)
}
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4 changes: 2 additions & 2 deletions accounts/abi/packing.go
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Expand Up @@ -25,7 +25,7 @@ import (
// packBytesSlice packs the given bytes as [L, V] as the canonical representation
// bytes slice
func packBytesSlice(bytes []byte, l int) []byte {
len := packNum(reflect.ValueOf(l), UintTy)
len := packNum(reflect.ValueOf(l))
return append(len, common.RightPadBytes(bytes, (l+31)/32*32)...)
}

Expand All @@ -34,7 +34,7 @@ func packBytesSlice(bytes []byte, l int) []byte {
func packElement(t Type, reflectValue reflect.Value) []byte {
switch t.T {
case IntTy, UintTy:
return packNum(reflectValue, t.T)
return packNum(reflectValue)
case StringTy:
return packBytesSlice([]byte(reflectValue.String()), reflectValue.Len())
case AddressTy:
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