1 files changed, 216 insertions, 0 deletions
diff --git a/accounts/abi/unpack.go b/accounts/abi/unpack.go
new file mode 100644
index 000000000..57732797b
--- /dev/null
+++ b/accounts/abi/unpack.go
@@ -0,0 +1,216 @@
+// 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"
+)
+
+// unpacker is a utility interface that enables us to have
+// abstraction between events and methods and also to properly
+// "unpack" them; e.g. events use Inputs, methods use Outputs.
+type unpacker interface {
+	tupleUnpack(v interface{}, output []byte) error
+	singleUnpack(v interface{}, output []byte) error
+	isTupleReturn() bool
+}
+
+// reads the integer based on its kind
+func readInteger(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:
+		return new(big.Int).SetBytes(b)
+	}
+}
+
+// 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 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
+	slice := output[start : start+size*32]
+
+	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")
+	}
+
+	for i, j := start, 0; j*32 < len(slice); i, j = i+32, j+1 {
+		// this corrects the arrangement so that we get all the underlying array values
+		if t.Elem.T == ArrayTy && j != 0 {
+			i = start + t.Elem.Size*32*j
+		}
+		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
+}
+
+// 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, end   int
+		err          error
+	)
+
+	// if we require a length prefix, find the beginning word and size returned.
+	if t.requiresLengthPrefix() {
+		begin, end, err = lengthPrefixPointsTo(index, output)
+		if err != nil {
+			return nil, err
+		}
+	} else {
+		returnOutput = output[index : index+32]
+	}
+
+	switch t.T {
+	case SliceTy:
+		return forEachUnpack(t, output, begin, end)
+	case ArrayTy:
+		return forEachUnpack(t, output, index, t.Size)
+	case StringTy: // variable arrays are written at the end of the return bytes
+		return string(output[begin : begin+end]), nil
+	case IntTy, UintTy:
+		return readInteger(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+end], 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) {
+	offset := int(binary.BigEndian.Uint64(output[index+24 : index+32]))
+	if offset+32 > len(output) {
+		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)
+	}
+	length = int(binary.BigEndian.Uint64(output[offset+24 : offset+32]))
+	if offset+32+length > len(output) {
+		return 0, 0, fmt.Errorf("abi: cannot marshal in to go type: length insufficient %d require %d", len(output), offset+32+length)
+	}
+	start = offset + 32
+
+	//fmt.Printf("LENGTH PREFIX INFO: \nsize: %v\noffset: %v\nstart: %v\n", length, offset, start)
+	return
+}
+
+// checks for proper formatting of byte output
+func bytesAreProper(output []byte) error {
+	if len(output) == 0 {
+		return fmt.Errorf("abi: unmarshalling empty output")
+	} else if len(output)%32 != 0 {
+		return fmt.Errorf("abi: improperly formatted output")
+	} else {
+		return nil
+	}
+}