1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
|
// 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"
)
// 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
}
|
