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- // Copyright 2017 The go-ethereum Authors
- // This file is part of the go-ethereum library.
- //
- // The go-ethereum library is free software: you can redistribute it and/or modify
- // it under the terms of the GNU Lesser General Public License as published by
- // the Free Software Foundation, either version 3 of the License, or
- // (at your option) any later version.
- //
- // The go-ethereum library is distributed in the hope that it will be useful,
- // but WITHOUT ANY WARRANTY; without even the implied warranty of
- // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- // GNU Lesser General Public License for more details.
- //
- // You should have received a copy of the GNU Lesser General Public License
- // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
- package abi
- import (
- "encoding/binary"
- "fmt"
- "math/big"
- "reflect"
- "github.com/ethereum/go-ethereum/common"
- )
- var (
- // MaxUint256 is the maximum value that can be represented by a uint256.
- MaxUint256 = new(big.Int).Sub(new(big.Int).Lsh(common.Big1, 256), common.Big1)
- // MaxInt256 is the maximum value that can be represented by a int256.
- MaxInt256 = new(big.Int).Sub(new(big.Int).Lsh(common.Big1, 255), common.Big1)
- )
- // ReadInteger reads the integer based on its kind and returns the appropriate value.
- func ReadInteger(typ Type, b []byte) interface{} {
- if typ.T == UintTy {
- switch typ.Size {
- case 8:
- return b[len(b)-1]
- case 16:
- return binary.BigEndian.Uint16(b[len(b)-2:])
- case 32:
- return binary.BigEndian.Uint32(b[len(b)-4:])
- case 64:
- return binary.BigEndian.Uint64(b[len(b)-8:])
- default:
- // the only case left for unsigned integer is uint256.
- return new(big.Int).SetBytes(b)
- }
- }
- switch typ.Size {
- case 8:
- return int8(b[len(b)-1])
- case 16:
- return int16(binary.BigEndian.Uint16(b[len(b)-2:]))
- case 32:
- return int32(binary.BigEndian.Uint32(b[len(b)-4:]))
- case 64:
- return int64(binary.BigEndian.Uint64(b[len(b)-8:]))
- default:
- // the only case left for integer is int256
- // big.SetBytes can't tell if a number is negative or positive in itself.
- // On EVM, if the returned number > max int256, it is negative.
- // A number is > max int256 if the bit at position 255 is set.
- ret := new(big.Int).SetBytes(b)
- if ret.Bit(255) == 1 {
- ret.Add(MaxUint256, new(big.Int).Neg(ret))
- ret.Add(ret, common.Big1)
- ret.Neg(ret)
- }
- return ret
- }
- }
- // readBool reads a bool.
- func readBool(word []byte) (bool, error) {
- for _, b := range word[:31] {
- if b != 0 {
- return false, errBadBool
- }
- }
- switch word[31] {
- case 0:
- return false, nil
- case 1:
- return true, nil
- default:
- return false, errBadBool
- }
- }
- // A function type is simply the address with the function selection signature at the end.
- //
- // readFunctionType enforces that standard by always presenting it as a 24-array (address + sig = 24 bytes)
- func readFunctionType(t Type, word []byte) (funcTy [24]byte, err error) {
- if t.T != FunctionTy {
- return [24]byte{}, fmt.Errorf("abi: invalid type in call to make function type byte array")
- }
- if garbage := binary.BigEndian.Uint64(word[24:32]); garbage != 0 {
- err = fmt.Errorf("abi: got improperly encoded function type, got %v", word)
- } else {
- copy(funcTy[:], word[0:24])
- }
- return
- }
- // ReadFixedBytes uses reflection to create a fixed array to be read from.
- func ReadFixedBytes(t Type, word []byte) (interface{}, error) {
- if t.T != FixedBytesTy {
- return nil, fmt.Errorf("abi: invalid type in call to make fixed byte array")
- }
- // convert
- array := reflect.New(t.GetType()).Elem()
- reflect.Copy(array, reflect.ValueOf(word[0:t.Size]))
- return array.Interface(), nil
- }
- // forEachUnpack iteratively unpack elements.
- func forEachUnpack(t Type, output []byte, start, size int) (interface{}, error) {
- if size < 0 {
- return nil, fmt.Errorf("cannot marshal input to array, size is negative (%d)", size)
- }
- if start+32*size > len(output) {
- 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)
- }
- // this value will become our slice or our array, depending on the type
- var refSlice reflect.Value
- if t.T == SliceTy {
- // declare our slice
- refSlice = reflect.MakeSlice(t.GetType(), size, size)
- } else if t.T == ArrayTy {
- // declare our array
- refSlice = reflect.New(t.GetType()).Elem()
- } else {
- return nil, fmt.Errorf("abi: invalid type in array/slice unpacking stage")
- }
- // Arrays have packed elements, resulting in longer unpack steps.
- // Slices have just 32 bytes per element (pointing to the contents).
- elemSize := getTypeSize(*t.Elem)
- for i, j := start, 0; j < size; i, j = i+elemSize, j+1 {
- inter, err := toGoType(i, *t.Elem, output)
- if err != nil {
- return nil, err
- }
- // append the item to our reflect slice
- refSlice.Index(j).Set(reflect.ValueOf(inter))
- }
- // return the interface
- return refSlice.Interface(), nil
- }
- func forTupleUnpack(t Type, output []byte) (interface{}, error) {
- retval := reflect.New(t.GetType()).Elem()
- virtualArgs := 0
- for index, elem := range t.TupleElems {
- marshalledValue, err := toGoType((index+virtualArgs)*32, *elem, output)
- if elem.T == ArrayTy && !isDynamicType(*elem) {
- // If we have a static array, like [3]uint256, these are coded as
- // just like uint256,uint256,uint256.
- // This means that we need to add two 'virtual' arguments when
- // we count the index from now on.
- //
- // Array values nested multiple levels deep are also encoded inline:
- // [2][3]uint256: uint256,uint256,uint256,uint256,uint256,uint256
- //
- // Calculate the full array size to get the correct offset for the next argument.
- // Decrement it by 1, as the normal index increment is still applied.
- virtualArgs += getTypeSize(*elem)/32 - 1
- } else if elem.T == TupleTy && !isDynamicType(*elem) {
- // If we have a static tuple, like (uint256, bool, uint256), these are
- // coded as just like uint256,bool,uint256
- virtualArgs += getTypeSize(*elem)/32 - 1
- }
- if err != nil {
- return nil, err
- }
- retval.Field(index).Set(reflect.ValueOf(marshalledValue))
- }
- return retval.Interface(), nil
- }
- // toGoType parses the output bytes and recursively assigns the value of these bytes
- // into a go type with accordance with the ABI spec.
- func toGoType(index int, t Type, output []byte) (interface{}, error) {
- if index+32 > len(output) {
- return nil, fmt.Errorf("abi: cannot marshal in to go type: length insufficient %d require %d", len(output), index+32)
- }
- var (
- returnOutput []byte
- begin, length int
- err error
- )
- // if we require a length prefix, find the beginning word and size returned.
- if t.requiresLengthPrefix() {
- begin, length, err = lengthPrefixPointsTo(index, output)
- if err != nil {
- return nil, err
- }
- } else {
- returnOutput = output[index : index+32]
- }
- switch t.T {
- case TupleTy:
- if isDynamicType(t) {
- begin, err := tuplePointsTo(index, output)
- if err != nil {
- return nil, err
- }
- return forTupleUnpack(t, output[begin:])
- }
- return forTupleUnpack(t, output[index:])
- case SliceTy:
- return forEachUnpack(t, output[begin:], 0, length)
- case ArrayTy:
- if isDynamicType(*t.Elem) {
- offset := binary.BigEndian.Uint64(returnOutput[len(returnOutput)-8:])
- if offset > uint64(len(output)) {
- return nil, fmt.Errorf("abi: toGoType offset greater than output length: offset: %d, len(output): %d", offset, len(output))
- }
- return forEachUnpack(t, output[offset:], 0, t.Size)
- }
- return forEachUnpack(t, output[index:], 0, t.Size)
- case StringTy: // variable arrays are written at the end of the return bytes
- return string(output[begin : begin+length]), nil
- case IntTy, UintTy:
- return ReadInteger(t, returnOutput), nil
- case BoolTy:
- return readBool(returnOutput)
- case AddressTy:
- return common.BytesToAddress(returnOutput), nil
- case HashTy:
- return common.BytesToHash(returnOutput), nil
- case BytesTy:
- return output[begin : begin+length], nil
- case FixedBytesTy:
- return ReadFixedBytes(t, returnOutput)
- case FunctionTy:
- return readFunctionType(t, returnOutput)
- default:
- return nil, fmt.Errorf("abi: unknown type %v", t.T)
- }
- }
- // lengthPrefixPointsTo interprets a 32 byte slice as an offset and then determines which indices to look to decode the type.
- func lengthPrefixPointsTo(index int, output []byte) (start int, length int, err error) {
- bigOffsetEnd := big.NewInt(0).SetBytes(output[index : index+32])
- bigOffsetEnd.Add(bigOffsetEnd, common.Big32)
- outputLength := big.NewInt(int64(len(output)))
- if bigOffsetEnd.Cmp(outputLength) > 0 {
- return 0, 0, fmt.Errorf("abi: cannot marshal in to go slice: offset %v would go over slice boundary (len=%v)", bigOffsetEnd, outputLength)
- }
- if bigOffsetEnd.BitLen() > 63 {
- return 0, 0, fmt.Errorf("abi offset larger than int64: %v", bigOffsetEnd)
- }
- offsetEnd := int(bigOffsetEnd.Uint64())
- lengthBig := big.NewInt(0).SetBytes(output[offsetEnd-32 : offsetEnd])
- totalSize := big.NewInt(0)
- totalSize.Add(totalSize, bigOffsetEnd)
- totalSize.Add(totalSize, lengthBig)
- if totalSize.BitLen() > 63 {
- return 0, 0, fmt.Errorf("abi: length larger than int64: %v", totalSize)
- }
- if totalSize.Cmp(outputLength) > 0 {
- return 0, 0, fmt.Errorf("abi: cannot marshal in to go type: length insufficient %v require %v", outputLength, totalSize)
- }
- start = int(bigOffsetEnd.Uint64())
- length = int(lengthBig.Uint64())
- return
- }
- // tuplePointsTo resolves the location reference for dynamic tuple.
- func tuplePointsTo(index int, output []byte) (start int, err error) {
- offset := big.NewInt(0).SetBytes(output[index : index+32])
- outputLen := big.NewInt(int64(len(output)))
- if offset.Cmp(big.NewInt(int64(len(output)))) > 0 {
- return 0, fmt.Errorf("abi: cannot marshal in to go slice: offset %v would go over slice boundary (len=%v)", offset, outputLen)
- }
- if offset.BitLen() > 63 {
- return 0, fmt.Errorf("abi offset larger than int64: %v", offset)
- }
- return int(offset.Uint64()), nil
- }
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