1 files changed, 295 insertions, 0 deletions
diff --git a/accounts/abi/unpack.go b/accounts/abi/unpack.go
new file mode 100644
index 0000000..d3cd310
--- /dev/null
+++ b/accounts/abi/unpack.go
@@ -0,0 +1,295 @@
+// 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/ava-labs/go-ethereum/common"
+)
+
+var (
+	maxUint256 = big.NewInt(0).Add(
+		big.NewInt(0).Exp(big.NewInt(2), big.NewInt(256), nil),
+		big.NewInt(-1))
+	maxInt256 = big.NewInt(0).Add(
+		big.NewInt(0).Exp(big.NewInt(2), big.NewInt(255), nil),
+		big.NewInt(-1))
+)
+
+// reads the integer based on its kind
+func readInteger(typ byte, kind reflect.Kind, b []byte) interface{} {
+	switch kind {
+	case reflect.Uint8:
+		return 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:
+		// the only case lefts for integer is int256/uint256.
+		// big.SetBytes can't tell if a number is negative, positive on itself.
+		// On EVM, if the returned number > max int256, it is negative.
+		ret := new(big.Int).SetBytes(b)
+		if typ == UintTy {
+			return ret
+		}
+
+		if ret.Cmp(maxInt256) > 0 {
+			ret.Add(maxUint256, big.NewInt(0).Neg(ret))
+			ret.Add(ret, big.NewInt(1))
+			ret.Neg(ret)
+		}
+		return ret
+	}
+}
+
+// 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.
+// This 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
+}
+
+// through reflection, creates 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.Type).Elem()
+
+	reflect.Copy(array, reflect.ValueOf(word[0:t.Size]))
+	return array.Interface(), nil
+
+}
+
+// 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.Type, size, size)
+	} else if t.T == ArrayTy {
+		// declare our array
+		refSlice = reflect.New(t.Type).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.Type).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:])
+		} else {
+			return forTupleUnpack(t, output[index:])
+		}
+	case SliceTy:
+		return forEachUnpack(t, output[begin:], 0, length)
+	case ArrayTy:
+		if isDynamicType(*t.Elem) {
+			offset := int64(binary.BigEndian.Uint64(returnOutput[len(returnOutput)-8:]))
+			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.T, t.Kind, 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)
+	}
+}
+
+// interprets a 32 byte slice as an offset and then determines which indice 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
+}