accounts/abi: improve type handling, add event support (#14743)
This commit is contained in:
RJ Catalano
Felix Lange
@ -25,118 +25,16 @@ import (
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"github.com/ethereum/go-ethereum/common"
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)
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// toGoSliceType parses the input and casts it to the proper slice defined by the ABI
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// argument in T.
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func toGoSlice(i int, t Argument, output []byte) (interface{}, error) {
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index := i * 32
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// The slice must, at very least be large enough for the index+32 which is exactly the size required
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// for the [offset in output, size of offset].
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if index+32 > len(output) {
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return nil, fmt.Errorf("abi: cannot marshal in to go slice: insufficient size output %d require %d", len(output), index+32)
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}
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elem := t.Type.Elem
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// first we need to create a slice of the type
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var refSlice reflect.Value
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switch elem.T {
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case IntTy, UintTy, BoolTy:
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// create a new reference slice matching the element type
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switch t.Type.Kind {
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case reflect.Bool:
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refSlice = reflect.ValueOf([]bool(nil))
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case reflect.Uint8:
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refSlice = reflect.ValueOf([]uint8(nil))
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case reflect.Uint16:
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refSlice = reflect.ValueOf([]uint16(nil))
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case reflect.Uint32:
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refSlice = reflect.ValueOf([]uint32(nil))
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case reflect.Uint64:
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refSlice = reflect.ValueOf([]uint64(nil))
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case reflect.Int8:
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refSlice = reflect.ValueOf([]int8(nil))
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case reflect.Int16:
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refSlice = reflect.ValueOf([]int16(nil))
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case reflect.Int32:
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refSlice = reflect.ValueOf([]int32(nil))
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case reflect.Int64:
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refSlice = reflect.ValueOf([]int64(nil))
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default:
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refSlice = reflect.ValueOf([]*big.Int(nil))
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}
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case AddressTy: // address must be of slice Address
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refSlice = reflect.ValueOf([]common.Address(nil))
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case HashTy: // hash must be of slice hash
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refSlice = reflect.ValueOf([]common.Hash(nil))
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case FixedBytesTy:
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refSlice = reflect.ValueOf([][]byte(nil))
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default: // no other types are supported
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return nil, fmt.Errorf("abi: unsupported slice type %v", elem.T)
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}
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var slice []byte
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var size int
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var offset int
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if t.Type.IsSlice {
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// get the offset which determines the start of this array ...
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offset = int(binary.BigEndian.Uint64(output[index+24 : index+32]))
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if offset+32 > len(output) {
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return nil, fmt.Errorf("abi: cannot marshal in to go slice: offset %d would go over slice boundary (len=%d)", len(output), offset+32)
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}
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slice = output[offset:]
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// ... starting with the size of the array in elements ...
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size = int(binary.BigEndian.Uint64(slice[24:32]))
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slice = slice[32:]
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// ... and make sure that we've at the very least the amount of bytes
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// available in the buffer.
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if size*32 > len(slice) {
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return nil, fmt.Errorf("abi: cannot marshal in to go slice: insufficient size output %d require %d", len(output), offset+32+size*32)
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}
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// reslice to match the required size
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slice = slice[:size*32]
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} else if t.Type.IsArray {
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//get the number of elements in the array
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size = t.Type.SliceSize
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//check to make sure array size matches up
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if index+32*size > len(output) {
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return nil, fmt.Errorf("abi: cannot marshal in to go array: offset %d would go over slice boundary (len=%d)", len(output), index+32*size)
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}
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//slice is there for a fixed amount of times
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slice = output[index : index+size*32]
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}
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for i := 0; i < size; i++ {
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var (
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inter interface{} // interface type
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returnOutput = slice[i*32 : i*32+32] // the return output
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err error
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)
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// set inter to the correct type (cast)
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switch elem.T {
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case IntTy, UintTy:
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inter = readInteger(t.Type.Kind, returnOutput)
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case BoolTy:
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inter, err = readBool(returnOutput)
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if err != nil {
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return nil, err
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}
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case AddressTy:
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inter = common.BytesToAddress(returnOutput)
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case HashTy:
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inter = common.BytesToHash(returnOutput)
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case FixedBytesTy:
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inter = returnOutput
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}
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// append the item to our reflect slice
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refSlice = reflect.Append(refSlice, reflect.ValueOf(inter))
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}
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// return the interface
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return refSlice.Interface(), nil
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// unpacker is a utility interface that enables us to have
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// abstraction between events and methods and also to properly
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// "unpack" them; e.g. events use Inputs, methods use Outputs.
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type unpacker interface {
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tupleUnpack(v interface{}, output []byte) error
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singleUnpack(v interface{}, output []byte) error
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isTupleReturn() bool
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}
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// reads the integer based on its kind
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func readInteger(kind reflect.Kind, b []byte) interface{} {
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switch kind {
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case reflect.Uint8:
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@ -160,13 +58,10 @@ func readInteger(kind reflect.Kind, b []byte) interface{} {
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}
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}
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// reads a bool
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func readBool(word []byte) (bool, error) {
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if len(word) != 32 {
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return false, fmt.Errorf("abi: fatal error: incorrect word length")
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}
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for i, b := range word {
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if b != 0 && i != 31 {
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for _, b := range word[:31] {
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if b != 0 {
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return false, errBadBool
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}
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}
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@ -178,58 +73,144 @@ func readBool(word []byte) (bool, error) {
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default:
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return false, errBadBool
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}
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}
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// A function type is simply the address with the function selection signature at the end.
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// This enforces that standard by always presenting it as a 24-array (address + sig = 24 bytes)
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func readFunctionType(t Type, word []byte) (funcTy [24]byte, err error) {
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if t.T != FunctionTy {
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return [24]byte{}, fmt.Errorf("abi: invalid type in call to make function type byte array.")
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}
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if garbage := binary.BigEndian.Uint64(word[24:32]); garbage != 0 {
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err = fmt.Errorf("abi: got improperly encoded function type, got %v", word)
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} else {
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copy(funcTy[:], word[0:24])
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}
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return
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}
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// through reflection, creates a fixed array to be read from
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func readFixedBytes(t Type, word []byte) (interface{}, error) {
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if t.T != FixedBytesTy {
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return nil, fmt.Errorf("abi: invalid type in call to make fixed byte array.")
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}
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// convert
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array := reflect.New(t.Type).Elem()
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reflect.Copy(array, reflect.ValueOf(word[0:t.Size]))
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return array.Interface(), nil
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}
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// toGoType parses the input and casts it to the proper type defined by the ABI
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// argument in T.
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func toGoType(i int, t Argument, output []byte) (interface{}, error) {
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// we need to treat slices differently
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if (t.Type.IsSlice || t.Type.IsArray) && t.Type.T != BytesTy && t.Type.T != StringTy && t.Type.T != FixedBytesTy && t.Type.T != FunctionTy {
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return toGoSlice(i, t, output)
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// iteratively unpack elements
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func forEachUnpack(t Type, output []byte, start, size int) (interface{}, error) {
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if start+32*size > len(output) {
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return nil, fmt.Errorf("abi: cannot marshal in to go array: offset %d would go over slice boundary (len=%d)", len(output), start+32*size)
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}
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index := i * 32
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// this value will become our slice or our array, depending on the type
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var refSlice reflect.Value
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slice := output[start : start+size*32]
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if t.T == SliceTy {
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// declare our slice
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refSlice = reflect.MakeSlice(t.Type, size, size)
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} else if t.T == ArrayTy {
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// declare our array
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refSlice = reflect.New(t.Type).Elem()
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} else {
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return nil, fmt.Errorf("abi: invalid type in array/slice unpacking stage")
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}
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for i, j := start, 0; j*32 < len(slice); i, j = i+32, j+1 {
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// this corrects the arrangement so that we get all the underlying array values
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if t.Elem.T == ArrayTy && j != 0 {
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i = start + t.Elem.Size*32*j
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}
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inter, err := toGoType(i, *t.Elem, output)
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if err != nil {
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return nil, err
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}
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// append the item to our reflect slice
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refSlice.Index(j).Set(reflect.ValueOf(inter))
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}
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// return the interface
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return refSlice.Interface(), nil
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}
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// toGoType parses the output bytes and recursively assigns the value of these bytes
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// into a go type with accordance with the ABI spec.
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func toGoType(index int, t Type, output []byte) (interface{}, error) {
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if index+32 > len(output) {
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return nil, fmt.Errorf("abi: cannot marshal in to go type: length insufficient %d require %d", len(output), index+32)
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}
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// Parse the given index output and check whether we need to read
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// a different offset and length based on the type (i.e. string, bytes)
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var returnOutput []byte
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switch t.Type.T {
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case StringTy, BytesTy: // variable arrays are written at the end of the return bytes
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// parse offset from which we should start reading
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offset := int(binary.BigEndian.Uint64(output[index+24 : index+32]))
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if offset+32 > len(output) {
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return nil, fmt.Errorf("abi: cannot marshal in to go type: length insufficient %d require %d", len(output), offset+32)
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}
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// parse the size up until we should be reading
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size := int(binary.BigEndian.Uint64(output[offset+24 : offset+32]))
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if offset+32+size > len(output) {
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return nil, fmt.Errorf("abi: cannot marshal in to go type: length insufficient %d require %d", len(output), offset+32+size)
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}
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var (
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returnOutput []byte
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begin, end int
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err error
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)
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// get the bytes for this return value
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returnOutput = output[offset+32 : offset+32+size]
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default:
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// if we require a length prefix, find the beginning word and size returned.
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if t.requiresLengthPrefix() {
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begin, end, err = lengthPrefixPointsTo(index, output)
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if err != nil {
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return nil, err
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}
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} else {
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returnOutput = output[index : index+32]
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}
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// convert the bytes to whatever is specified by the ABI.
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switch t.Type.T {
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switch t.T {
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case SliceTy:
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return forEachUnpack(t, output, begin, end)
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case ArrayTy:
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return forEachUnpack(t, output, index, t.Size)
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case StringTy: // variable arrays are written at the end of the return bytes
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return string(output[begin : begin+end]), nil
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case IntTy, UintTy:
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return readInteger(t.Type.Kind, returnOutput), nil
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return readInteger(t.Kind, returnOutput), nil
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case BoolTy:
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return readBool(returnOutput)
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case AddressTy:
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return common.BytesToAddress(returnOutput), nil
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case HashTy:
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return common.BytesToHash(returnOutput), nil
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case BytesTy, FixedBytesTy, FunctionTy:
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return returnOutput, nil
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case StringTy:
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return string(returnOutput), nil
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case BytesTy:
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return output[begin : begin+end], nil
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case FixedBytesTy:
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return readFixedBytes(t, returnOutput)
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case FunctionTy:
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return readFunctionType(t, returnOutput)
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default:
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return nil, fmt.Errorf("abi: unknown type %v", t.T)
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}
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}
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// interprets a 32 byte slice as an offset and then determines which indice to look to decode the type.
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func lengthPrefixPointsTo(index int, output []byte) (start int, length int, err error) {
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offset := int(binary.BigEndian.Uint64(output[index+24 : index+32]))
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if offset+32 > len(output) {
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return 0, 0, fmt.Errorf("abi: cannot marshal in to go slice: offset %d would go over slice boundary (len=%d)", len(output), offset+32)
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}
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length = int(binary.BigEndian.Uint64(output[offset+24 : offset+32]))
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if offset+32+length > len(output) {
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return 0, 0, fmt.Errorf("abi: cannot marshal in to go type: length insufficient %d require %d", len(output), offset+32+length)
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}
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start = offset + 32
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//fmt.Printf("LENGTH PREFIX INFO: \nsize: %v\noffset: %v\nstart: %v\n", length, offset, start)
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return
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}
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// checks for proper formatting of byte output
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func bytesAreProper(output []byte) error {
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if len(output) == 0 {
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return fmt.Errorf("abi: unmarshalling empty output")
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} else if len(output)%32 != 0 {
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return fmt.Errorf("abi: improperly formatted output")
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} else {
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return nil
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}
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return nil, fmt.Errorf("abi: unknown type %v", t.Type.T)
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}
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