neoneo-go/pkg/vm/stackitem/json.go

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package stackitem
import (
"bytes"
"encoding/base64"
"encoding/json"
"errors"
"fmt"
gio "io"
"math/big"
"strconv"
"strings"
)
// decoder is a wrapper around json.Decoder helping to mimic C# json decoder behavior.
type decoder struct {
json.Decoder
count int
depth int
// bestIntPrecision denotes whether maximum allowed integer precision should
// be used to parse big.Int items. If false, then default NeoC# value will be
// used which doesn't allow to precisely parse big values. This behaviour is
// managed by the config.HFBasilisk.
bestIntPrecision bool
}
// MaxAllowedInteger is the maximum integer allowed to be encoded.
const MaxAllowedInteger = 2<<53 - 1
// MaxJSONDepth is the maximum allowed nesting level of an encoded/decoded JSON.
const MaxJSONDepth = 10
const (
// MaxIntegerPrec is the maximum precision allowed for big.Integer parsing.
// It allows to properly parse integer numbers that our 256-bit VM is able to
// handle.
MaxIntegerPrec = 1<<8 + 1
// CompatIntegerPrec is the maximum precision allowed for big.Integer parsing
// by the C# node before the Basilisk hardfork. It doesn't allow to precisely
// parse big numbers, see the https://github.com/neo-project/neo/issues/2879.
CompatIntegerPrec = 53
)
// ErrInvalidValue is returned when an item value doesn't fit some constraints
// during serialization or deserialization.
var ErrInvalidValue = errors.New("invalid value")
// ErrTooDeep is returned when JSON encoder/decoder goes beyond MaxJSONDepth in
// its processing.
var ErrTooDeep = errors.New("too deep")
// ToJSON encodes Item to JSON.
// It behaves as following:
//
// ByteArray -> base64 string
// BigInteger -> number
// Bool -> bool
// Null -> null
// Array, Struct -> array
// Map -> map with keys as UTF-8 bytes
func ToJSON(item Item) ([]byte, error) {
seen := make(map[Item]sliceNoPointer, typicalNumOfItems)
return toJSON(nil, seen, item)
}
// sliceNoPointer represents a sub-slice of a known slice.
// It doesn't contain any pointer and uses the same amount of memory as `[]byte`,
// but at the same type has additional information about the number of items in
// the stackitem (including the stackitem itself).
type sliceNoPointer struct {
start, end int
itemsCount int
}
func toJSON(data []byte, seen map[Item]sliceNoPointer, item Item) ([]byte, error) {
if len(data) > MaxSize {
return nil, errTooBigSize
}
if old, ok := seen[item]; ok {
if len(data)+old.end-old.start > MaxSize {
return nil, errTooBigSize
}
return append(data, data[old.start:old.end]...), nil
}
start := len(data)
var err error
switch it := item.(type) {
case *Array, *Struct:
var items []Item
if a, ok := it.(*Array); ok {
items = a.value
} else {
items = it.(*Struct).value
}
data = append(data, '[')
for i, v := range items {
data, err = toJSON(data, seen, v)
if err != nil {
return nil, err
}
if i < len(items)-1 {
data = append(data, ',')
}
}
data = append(data, ']')
seen[item] = sliceNoPointer{start: start, end: len(data)}
case *Map:
data = append(data, '{')
for i := range it.value {
// map key can always be converted to []byte
// but are not always a valid UTF-8.
raw, err := itemToJSONString(it.value[i].Key)
if err != nil {
return nil, err
}
data = append(data, raw...)
data = append(data, ':')
data, err = toJSON(data, seen, it.value[i].Value)
if err != nil {
return nil, err
}
if i < len(it.value)-1 {
data = append(data, ',')
}
}
data = append(data, '}')
seen[item] = sliceNoPointer{start: start, end: len(data)}
case *BigInteger:
if it.Big().CmpAbs(big.NewInt(MaxAllowedInteger)) == 1 {
return nil, fmt.Errorf("%w (MaxAllowedInteger)", ErrInvalidValue)
}
data = append(data, it.Big().String()...)
case *ByteArray, *Buffer:
raw, err := itemToJSONString(it)
if err != nil {
return nil, err
}
data = append(data, raw...)
case Bool:
if it {
data = append(data, "true"...)
} else {
data = append(data, "false"...)
}
case Null:
data = append(data, "null"...)
default:
return nil, fmt.Errorf("%w: %s", ErrUnserializable, it.String())
}
if len(data) > MaxSize {
return nil, errTooBigSize
}
return data, nil
}
// itemToJSONString converts it to a string
// in quotation marks with control characters escaped.
func itemToJSONString(it Item) ([]byte, error) {
s, err := ToString(it)
if err != nil {
return nil, err
}
data, _ := json.Marshal(s) // error never occurs because `ToString` checks for validity
// ref https://github.com/neo-project/neo-modules/issues/375 and https://github.com/dotnet/runtime/issues/35281
return bytes.Replace(data, []byte{'+'}, []byte("\\u002B"), -1), nil
}
// FromJSON decodes an Item from JSON.
// It behaves as following:
//
// string -> ByteArray from base64
// number -> BigInteger
// bool -> Bool
// null -> Null
// array -> Array
// map -> Map, keys are UTF-8
func FromJSON(data []byte, maxCount int, bestIntPrecision bool) (Item, error) {
d := decoder{
Decoder: *json.NewDecoder(bytes.NewReader(data)),
count: maxCount,
bestIntPrecision: bestIntPrecision,
}
d.UseNumber()
item, err := d.decode()
if err != nil {
return nil, err
}
_, err = d.Token()
if !errors.Is(err, gio.EOF) {
return nil, fmt.Errorf("%w: unexpected items", ErrInvalidValue)
}
return item, nil
}
func (d *decoder) decode() (Item, error) {
tok, err := d.Token()
if err != nil {
return nil, err
}
d.count--
if d.count < 0 && tok != json.Delim('}') && tok != json.Delim(']') {
return nil, errTooBigElements
}
switch t := tok.(type) {
case json.Delim:
switch t {
case json.Delim('{'), json.Delim('['):
if d.depth == MaxJSONDepth {
return nil, ErrTooDeep
}
d.depth++
var item Item
if t == json.Delim('{') {
item, err = d.decodeMap()
} else {
item, err = d.decodeArray()
}
d.depth--
return item, err
default:
d.count++
// no error above means corresponding closing token
// was encountered for map or array respectively
return nil, nil
}
case string:
return NewByteArray([]byte(t)), nil
case json.Number:
ts := t.String()
var (
num *big.Int
ok bool
)
isScientific := strings.Contains(ts, "e+") || strings.Contains(ts, "E+")
if isScientific {
// As a special case numbers like 2.8e+22 are allowed (SetString rejects them).
// That's the way how C# code works.
var prec uint = CompatIntegerPrec
if d.bestIntPrecision {
prec = MaxIntegerPrec
}
f, _, err := big.ParseFloat(ts, 10, prec, big.ToNearestEven)
if err != nil {
return nil, fmt.Errorf("%w (malformed exp value for int)", ErrInvalidValue)
}
num = new(big.Int)
_, acc := f.Int(num)
ok = acc == big.Exact
} else {
dot := strings.IndexByte(ts, '.')
if dot != -1 {
// As a special case numbers like 123.000 are allowed (SetString rejects them).
// And yes, that's the way C# code works also.
for _, r := range ts[dot+1:] {
if r != '0' {
return nil, fmt.Errorf("%w (real value for int)", ErrInvalidValue)
}
}
ts = ts[:dot]
}
num, ok = new(big.Int).SetString(ts, 10)
}
if !ok {
return nil, fmt.Errorf("%w (integer)", ErrInvalidValue)
}
return NewBigInteger(num), nil
case bool:
return NewBool(t), nil
default:
// it can be only `nil`
return Null{}, nil
}
}
func (d *decoder) decodeArray() (*Array, error) {
items := []Item{}
for {
item, err := d.decode()
if err != nil {
return nil, err
}
if item == nil {
return NewArray(items), nil
}
items = append(items, item)
}
}
func (d *decoder) decodeMap() (*Map, error) {
m := NewMap()
for {
key, err := d.Token()
if err != nil {
return nil, err
}
k, ok := key.(string)
if !ok {
return m, nil
}
d.count--
if d.count < 0 {
return nil, errTooBigElements
}
val, err := d.decode()
if err != nil {
return nil, err
}
m.Add(NewByteArray([]byte(k)), val)
}
}
// ToJSONWithTypes serializes any stackitem to JSON in a lossless way.
func ToJSONWithTypes(item Item) ([]byte, error) {
return toJSONWithTypes(nil, item, make(map[Item]sliceNoPointer, typicalNumOfItems))
}
func toJSONWithTypes(data []byte, item Item, seen map[Item]sliceNoPointer) ([]byte, error) {
if item == nil {
return nil, fmt.Errorf("%w: nil", ErrUnserializable)
}
if old, ok := seen[item]; ok {
if old.end == 0 {
// Compound item marshaling which has not yet finished.
return nil, ErrRecursive
}
if len(data)+old.end-old.start > MaxSize {
return nil, errTooBigSize
}
return append(data, data[old.start:old.end]...), nil
}
var val string
var hasValue bool
switch item.(type) {
case Null:
val = `{"type":"Any"}`
case *Interop:
val = `{"type":"InteropInterface"}`
default:
val = `{"type":"` + item.Type().String() + `","value":`
hasValue = true
}
if len(data)+len(val) > MaxSize {
return nil, errTooBigSize
}
start := len(data)
data = append(data, val...)
if !hasValue {
return data, nil
}
// Primitive stack items are appended after the switch
// to reduce the amount of size checks.
var primitive string
var isBuffer bool
var err error
switch it := item.(type) {
case *Array, *Struct:
seen[item] = sliceNoPointer{}
data = append(data, '[')
for i, elem := range it.Value().([]Item) {
if i != 0 {
data = append(data, ',')
}
data, err = toJSONWithTypes(data, elem, seen)
if err != nil {
return nil, err
}
}
case Bool:
if it {
primitive = "true"
} else {
primitive = "false"
}
case *ByteArray:
primitive = `"` + base64.StdEncoding.EncodeToString(it.Value().([]byte)) + `"`
case *Buffer:
isBuffer = true
primitive = `"` + base64.StdEncoding.EncodeToString(it.Value().([]byte)) + `"`
case *BigInteger:
primitive = `"` + it.Big().String() + `"`
case *Map:
seen[item] = sliceNoPointer{}
data = append(data, '[')
for i := range it.value {
if i != 0 {
data = append(data, ',')
}
data = append(data, `{"key":`...)
data, err = toJSONWithTypes(data, it.value[i].Key, seen)
if err != nil {
return nil, err
}
data = append(data, `,"value":`...)
data, err = toJSONWithTypes(data, it.value[i].Value, seen)
if err != nil {
return nil, err
}
data = append(data, '}')
}
case *Pointer:
primitive = strconv.Itoa(it.pos)
}
if len(primitive) != 0 {
if len(data)+len(primitive)+1 > MaxSize {
return nil, errTooBigSize
}
data = append(data, primitive...)
data = append(data, '}')
if isBuffer {
seen[item] = sliceNoPointer{start: start, end: len(data)}
}
} else {
if len(data)+2 > MaxSize { // also take care of '}'
return nil, errTooBigSize
}
data = append(data, ']', '}')
seen[item] = sliceNoPointer{start: start, end: len(data)}
}
return data, nil
}
type (
rawItem struct {
Type string `json:"type"`
Value json.RawMessage `json:"value,omitempty"`
}
rawMapElement struct {
Key json.RawMessage `json:"key"`
Value json.RawMessage `json:"value"`
}
)
func mkErrValue(err error) error {
return fmt.Errorf("%w: %v", ErrInvalidValue, err) //nolint:errorlint // errorlint: non-wrapping format verb for fmt.Errorf. Use `%w` to format errors
}
// FromJSONWithTypes deserializes an item from typed-json representation.
func FromJSONWithTypes(data []byte) (Item, error) {
raw := new(rawItem)
if err := json.Unmarshal(data, raw); err != nil {
return nil, err
}
typ, err := FromString(raw.Type)
if err != nil {
return nil, fmt.Errorf("%w: %v", ErrInvalidType, raw.Type)
}
switch typ {
case AnyT:
return Null{}, nil
case PointerT:
var pos int
if err := json.Unmarshal(raw.Value, &pos); err != nil {
return nil, mkErrValue(err)
}
return NewPointer(pos, nil), nil
case BooleanT:
var b bool
if err := json.Unmarshal(raw.Value, &b); err != nil {
return nil, mkErrValue(err)
}
return NewBool(b), nil
case IntegerT:
var s string
if err := json.Unmarshal(raw.Value, &s); err != nil {
return nil, mkErrValue(err)
}
val, ok := new(big.Int).SetString(s, 10)
if !ok {
return nil, mkErrValue(errors.New("not an integer"))
}
return NewBigInteger(val), nil
case ByteArrayT, BufferT:
var s string
if err := json.Unmarshal(raw.Value, &s); err != nil {
return nil, mkErrValue(err)
}
val, err := base64.StdEncoding.DecodeString(s)
if err != nil {
return nil, mkErrValue(err)
}
if typ == ByteArrayT {
return NewByteArray(val), nil
}
return NewBuffer(val), nil
case ArrayT, StructT:
var arr []json.RawMessage
if err := json.Unmarshal(raw.Value, &arr); err != nil {
return nil, mkErrValue(err)
}
items := make([]Item, len(arr))
for i := range arr {
it, err := FromJSONWithTypes(arr[i])
if err != nil {
return nil, err
}
items[i] = it
}
if typ == ArrayT {
return NewArray(items), nil
}
return NewStruct(items), nil
case MapT:
var arr []rawMapElement
if err := json.Unmarshal(raw.Value, &arr); err != nil {
return nil, mkErrValue(err)
}
m := NewMap()
for i := range arr {
key, err := FromJSONWithTypes(arr[i].Key)
if err != nil {
return nil, err
2020-09-29 07:56:57 +00:00
} else if err = IsValidMapKey(key); err != nil {
return nil, err
}
value, err := FromJSONWithTypes(arr[i].Value)
if err != nil {
return nil, err
}
m.Add(key, value)
}
return m, nil
case InteropT:
return NewInterop(nil), nil
default:
return nil, fmt.Errorf("%w: %v", ErrInvalidType, typ)
}
}