// Copyright 2015 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"
)
// toGoSliceType parses the input and casts it to the proper slice defined by the ABI
// argument in T.
func toGoSlice(i int, t Argument, output []byte) (interface{}, error) {
index := i * 32
// The slice must, at very least be large enough for the index+32 which is exactly the size required
// for the [offset in output, size of offset].
if index+32 > len(output) {
return nil, fmt.Errorf("abi: cannot marshal in to go slice: insufficient size output %d require %d", len(output), index+32)
}
elem := t.Type.Elem
// first we need to create a slice of the type
var refSlice reflect.Value
switch elem.T {
case IntTy, UintTy, BoolTy:
// create a new reference slice matching the element type
switch t.Type.Kind {
case reflect.Bool:
refSlice = reflect.ValueOf([]bool(nil))
case reflect.Uint8:
refSlice = reflect.ValueOf([]uint8(nil))
case reflect.Uint16:
refSlice = reflect.ValueOf([]uint16(nil))
case reflect.Uint32:
refSlice = reflect.ValueOf([]uint32(nil))
case reflect.Uint64:
refSlice = reflect.ValueOf([]uint64(nil))
case reflect.Int8:
refSlice = reflect.ValueOf([]int8(nil))
case reflect.Int16:
refSlice = reflect.ValueOf([]int16(nil))
case reflect.Int32:
refSlice = reflect.ValueOf([]int32(nil))
case reflect.Int64:
refSlice = reflect.ValueOf([]int64(nil))
default:
refSlice = reflect.ValueOf([]*big.Int(nil))
}
case AddressTy: // address must be of slice Address
refSlice = reflect.ValueOf([]common.Address(nil))
case HashTy: // hash must be of slice hash
refSlice = reflect.ValueOf([]common.Hash(nil))
case FixedBytesTy:
refSlice = reflect.ValueOf([][]byte(nil))
default: // no other types are supported
return nil, fmt.Errorf("abi: unsupported slice type %v", elem.T)
}
var slice []byte
var size int
var offset int
if t.Type.IsSlice {
// get the offset which determines the start of this array ...
offset = int(binary.BigEndian.Uint64(output[index+24 : index+32]))
if offset+32 > len(output) {
return nil, fmt.Errorf("abi: cannot marshal in to go slice: offset %d would go over slice boundary (len=%d)", len(output), offset+32)
}
slice = output[offset:]
// ... starting with the size of the array in elements ...
size = int(binary.BigEndian.Uint64(slice[24:32]))
slice = slice[32:]
// ... and make sure that we've at the very least the amount of bytes
// available in the buffer.
if size*32 > len(slice) {
return nil, fmt.Errorf("abi: cannot marshal in to go slice: insufficient size output %d require %d", len(output), offset+32+size*32)
}
// reslice to match the required size
slice = slice[:size*32]
} else if t.Type.IsArray {
//get the number of elements in the array
size = t.Type.SliceSize
//check to make sure array size matches up
if index+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), index+32*size)
}
//slice is there for a fixed amount of times
slice = output[index : index+size*32]
}
for i := 0; i < size; i++ {
var (
inter interface{} // interface type
returnOutput = slice[i*32 : i*32+32] // the return output
err error
)
// set inter to the correct type (cast)
switch elem.T {
case IntTy, UintTy:
inter = readInteger(t.Type.Kind, returnOutput)
case BoolTy:
inter, err = readBool(returnOutput)
if err != nil {
return nil, err
}
case AddressTy:
inter = common.BytesToAddress(returnOutput)
case HashTy:
inter = common.BytesToHash(returnOutput)
case FixedBytesTy:
inter = returnOutput
}
// append the item to our reflect slice
refSlice = reflect.Append(refSlice, reflect.ValueOf(inter))
}
// return the interface
return refSlice.Interface(), nil
}
func readInteger(kind reflect.Kind, b []byte) interface{} {
switch kind {
case reflect.Uint8:
return uint8(b[len(b)-1])
case reflect.Uint16:
return binary.BigEndian.Uint16(b[len(b)-2:])
case reflect.Uint32:
return binary.BigEndian.Uint32(b[len(b)-4:])
case reflect.Uint64:
return binary.BigEndian.Uint64(b[len(b)-8:])
case reflect.Int8:
return int8(b[len(b)-1])
case reflect.Int16:
return int16(binary.BigEndian.Uint16(b[len(b)-2:]))
case reflect.Int32:
return int32(binary.BigEndian.Uint32(b[len(b)-4:]))
case reflect.Int64:
return int64(binary.BigEndian.Uint64(b[len(b)-8:]))
default:
return new(big.Int).SetBytes(b)
}
}
func readBool(word []byte) (bool, error) {
if len(word) != 32 {
return false, fmt.Errorf("abi: fatal error: incorrect word length")
}
for i, b := range word {
if b != 0 && i != 31 {
return false, errBadBool
}
}
switch word[31] {
case 0:
return false, nil
case 1:
return true, nil
default:
return false, errBadBool
}
}
// toGoType parses the input and casts it to the proper type defined by the ABI
// argument in T.
func toGoType(i int, t Argument, output []byte) (interface{}, error) {
// we need to treat slices differently
if (t.Type.IsSlice || t.Type.IsArray) && t.Type.T != BytesTy && t.Type.T != StringTy && t.Type.T != FixedBytesTy && t.Type.T != FunctionTy {
return toGoSlice(i, t, output)
}
index := i * 32
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)
}
// Parse the given index output and check whether we need to read
// a different offset and length based on the type (i.e. string, bytes)
var returnOutput []byte
switch t.Type.T {
case StringTy, BytesTy: // variable arrays are written at the end of the return bytes
// parse offset from which we should start reading
offset := int(binary.BigEndian.Uint64(output[index+24 : index+32]))
if offset+32 > len(output) {
return nil, fmt.Errorf("abi: cannot marshal in to go type: length insufficient %d require %d", len(output), offset+32)
}
// parse the size up until we should be reading
size := int(binary.BigEndian.Uint64(output[offset+24 : offset+32]))
if offset+32+size > len(output) {
return nil, fmt.Errorf("abi: cannot marshal in to go type: length insufficient %d require %d", len(output), offset+32+size)
}
// get the bytes for this return value
returnOutput = output[offset+32 : offset+32+size]
default:
returnOutput = output[index : index+32]
}
// convert the bytes to whatever is specified by the ABI.
switch t.Type.T {
case IntTy, UintTy:
return readInteger(t.Type.Kind, returnOutput), nil
case BoolTy:
return readBool(returnOutput)
case AddressTy:
return common.BytesToAddress(returnOutput), nil
case HashTy:
return common.BytesToHash(returnOutput), nil
case BytesTy, FixedBytesTy, FunctionTy:
return returnOutput, nil
case StringTy:
return string(returnOutput), nil
}
return nil, fmt.Errorf("abi: unknown type %v", t.Type.T)
}
