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authorDeterminant <[email protected]>2020-06-28 14:47:41 -0400
committerDeterminant <[email protected]>2020-06-28 14:47:41 -0400
commitd235e2c6a5788ec4a6cff15a16f56b38a3876a0d (patch)
tree5f2727f7a50ee5840f889c82776d3a30a88dd59b /accounts/abi/unpack.go
parent13ebd8bd9468e9d769d598b0ca2afb72ba78cb97 (diff)
...
Diffstat (limited to 'accounts/abi/unpack.go')
-rw-r--r--accounts/abi/unpack.go295
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
+}