Official Go implementation of the Ethereum protocol
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go-ethereum/vendor/github.com/oschwald/maxminddb-golang/decoder.go

722 lines
18 KiB

package maxminddb
import (
"encoding/binary"
"math"
"math/big"
"reflect"
"sync"
)
type decoder struct {
buffer []byte
}
type dataType int
const (
_Extended dataType = iota
_Pointer
_String
_Float64
_Bytes
_Uint16
_Uint32
_Map
_Int32
_Uint64
_Uint128
_Slice
_Container
_Marker
_Bool
_Float32
)
const (
// This is the value used in libmaxminddb
maximumDataStructureDepth = 512
)
func (d *decoder) decode(offset uint, result reflect.Value, depth int) (uint, error) {
if depth > maximumDataStructureDepth {
return 0, newInvalidDatabaseError("exceeded maximum data structure depth; database is likely corrupt")
}
typeNum, size, newOffset, err := d.decodeCtrlData(offset)
if err != nil {
return 0, err
}
if typeNum != _Pointer && result.Kind() == reflect.Uintptr {
result.Set(reflect.ValueOf(uintptr(offset)))
return d.nextValueOffset(offset, 1)
}
return d.decodeFromType(typeNum, size, newOffset, result, depth+1)
}
func (d *decoder) decodeCtrlData(offset uint) (dataType, uint, uint, error) {
newOffset := offset + 1
if offset >= uint(len(d.buffer)) {
return 0, 0, 0, newOffsetError()
}
ctrlByte := d.buffer[offset]
typeNum := dataType(ctrlByte >> 5)
if typeNum == _Extended {
if newOffset >= uint(len(d.buffer)) {
return 0, 0, 0, newOffsetError()
}
typeNum = dataType(d.buffer[newOffset] + 7)
newOffset++
}
var size uint
size, newOffset, err := d.sizeFromCtrlByte(ctrlByte, newOffset, typeNum)
return typeNum, size, newOffset, err
}
func (d *decoder) sizeFromCtrlByte(ctrlByte byte, offset uint, typeNum dataType) (uint, uint, error) {
size := uint(ctrlByte & 0x1f)
if typeNum == _Extended {
return size, offset, nil
}
var bytesToRead uint
if size < 29 {
return size, offset, nil
}
bytesToRead = size - 28
newOffset := offset + bytesToRead
if newOffset > uint(len(d.buffer)) {
return 0, 0, newOffsetError()
}
if size == 29 {
return 29 + uint(d.buffer[offset]), offset + 1, nil
}
sizeBytes := d.buffer[offset:newOffset]
switch {
case size == 30:
size = 285 + uintFromBytes(0, sizeBytes)
case size > 30:
size = uintFromBytes(0, sizeBytes) + 65821
}
return size, newOffset, nil
}
func (d *decoder) decodeFromType(
dtype dataType,
size uint,
offset uint,
result reflect.Value,
depth int,
) (uint, error) {
result = d.indirect(result)
// For these types, size has a special meaning
switch dtype {
case _Bool:
return d.unmarshalBool(size, offset, result)
case _Map:
return d.unmarshalMap(size, offset, result, depth)
case _Pointer:
return d.unmarshalPointer(size, offset, result, depth)
case _Slice:
return d.unmarshalSlice(size, offset, result, depth)
}
// For the remaining types, size is the byte size
if offset+size > uint(len(d.buffer)) {
return 0, newOffsetError()
}
switch dtype {
case _Bytes:
return d.unmarshalBytes(size, offset, result)
case _Float32:
return d.unmarshalFloat32(size, offset, result)
case _Float64:
return d.unmarshalFloat64(size, offset, result)
case _Int32:
return d.unmarshalInt32(size, offset, result)
case _String:
return d.unmarshalString(size, offset, result)
case _Uint16:
return d.unmarshalUint(size, offset, result, 16)
case _Uint32:
return d.unmarshalUint(size, offset, result, 32)
case _Uint64:
return d.unmarshalUint(size, offset, result, 64)
case _Uint128:
return d.unmarshalUint128(size, offset, result)
default:
return 0, newInvalidDatabaseError("unknown type: %d", dtype)
}
}
func (d *decoder) unmarshalBool(size uint, offset uint, result reflect.Value) (uint, error) {
if size > 1 {
return 0, newInvalidDatabaseError("the MaxMind DB file's data section contains bad data (bool size of %v)", size)
}
value, newOffset, err := d.decodeBool(size, offset)
if err != nil {
return 0, err
}
switch result.Kind() {
case reflect.Bool:
result.SetBool(value)
return newOffset, nil
case reflect.Interface:
if result.NumMethod() == 0 {
result.Set(reflect.ValueOf(value))
return newOffset, nil
}
}
return newOffset, newUnmarshalTypeError(value, result.Type())
}
// indirect follows pointers and create values as necessary. This is
// heavily based on encoding/json as my original version had a subtle
// bug. This method should be considered to be licensed under
// https://golang.org/LICENSE
func (d *decoder) indirect(result reflect.Value) reflect.Value {
for {
// Load value from interface, but only if the result will be
// usefully addressable.
if result.Kind() == reflect.Interface && !result.IsNil() {
e := result.Elem()
if e.Kind() == reflect.Ptr && !e.IsNil() {
result = e
continue
}
}
if result.Kind() != reflect.Ptr {
break
}
if result.IsNil() {
result.Set(reflect.New(result.Type().Elem()))
}
result = result.Elem()
}
return result
}
var sliceType = reflect.TypeOf([]byte{})
func (d *decoder) unmarshalBytes(size uint, offset uint, result reflect.Value) (uint, error) {
value, newOffset, err := d.decodeBytes(size, offset)
if err != nil {
return 0, err
}
switch result.Kind() {
case reflect.Slice:
if result.Type() == sliceType {
result.SetBytes(value)
return newOffset, nil
}
case reflect.Interface:
if result.NumMethod() == 0 {
result.Set(reflect.ValueOf(value))
return newOffset, nil
}
}
return newOffset, newUnmarshalTypeError(value, result.Type())
}
func (d *decoder) unmarshalFloat32(size uint, offset uint, result reflect.Value) (uint, error) {
if size != 4 {
return 0, newInvalidDatabaseError("the MaxMind DB file's data section contains bad data (float32 size of %v)", size)
}
value, newOffset, err := d.decodeFloat32(size, offset)
if err != nil {
return 0, err
}
switch result.Kind() {
case reflect.Float32, reflect.Float64:
result.SetFloat(float64(value))
return newOffset, nil
case reflect.Interface:
if result.NumMethod() == 0 {
result.Set(reflect.ValueOf(value))
return newOffset, nil
}
}
return newOffset, newUnmarshalTypeError(value, result.Type())
}
func (d *decoder) unmarshalFloat64(size uint, offset uint, result reflect.Value) (uint, error) {
if size != 8 {
return 0, newInvalidDatabaseError("the MaxMind DB file's data section contains bad data (float 64 size of %v)", size)
}
value, newOffset, err := d.decodeFloat64(size, offset)
if err != nil {
return 0, err
}
switch result.Kind() {
case reflect.Float32, reflect.Float64:
if result.OverflowFloat(value) {
return 0, newUnmarshalTypeError(value, result.Type())
}
result.SetFloat(value)
return newOffset, nil
case reflect.Interface:
if result.NumMethod() == 0 {
result.Set(reflect.ValueOf(value))
return newOffset, nil
}
}
return newOffset, newUnmarshalTypeError(value, result.Type())
}
func (d *decoder) unmarshalInt32(size uint, offset uint, result reflect.Value) (uint, error) {
if size > 4 {
return 0, newInvalidDatabaseError("the MaxMind DB file's data section contains bad data (int32 size of %v)", size)
}
value, newOffset, err := d.decodeInt(size, offset)
if err != nil {
return 0, err
}
switch result.Kind() {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
n := int64(value)
if !result.OverflowInt(n) {
result.SetInt(n)
return newOffset, nil
}
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
n := uint64(value)
if !result.OverflowUint(n) {
result.SetUint(n)
return newOffset, nil
}
case reflect.Interface:
if result.NumMethod() == 0 {
result.Set(reflect.ValueOf(value))
return newOffset, nil
}
}
return newOffset, newUnmarshalTypeError(value, result.Type())
}
func (d *decoder) unmarshalMap(
size uint,
offset uint,
result reflect.Value,
depth int,
) (uint, error) {
result = d.indirect(result)
switch result.Kind() {
default:
return 0, newUnmarshalTypeError("map", result.Type())
case reflect.Struct:
return d.decodeStruct(size, offset, result, depth)
case reflect.Map:
return d.decodeMap(size, offset, result, depth)
case reflect.Interface:
if result.NumMethod() == 0 {
rv := reflect.ValueOf(make(map[string]interface{}, size))
newOffset, err := d.decodeMap(size, offset, rv, depth)
result.Set(rv)
return newOffset, err
}
return 0, newUnmarshalTypeError("map", result.Type())
}
}
func (d *decoder) unmarshalPointer(size uint, offset uint, result reflect.Value, depth int) (uint, error) {
pointer, newOffset, err := d.decodePointer(size, offset)
if err != nil {
return 0, err
}
_, err = d.decode(pointer, result, depth)
return newOffset, err
}
func (d *decoder) unmarshalSlice(
size uint,
offset uint,
result reflect.Value,
depth int,
) (uint, error) {
switch result.Kind() {
case reflect.Slice:
return d.decodeSlice(size, offset, result, depth)
case reflect.Interface:
if result.NumMethod() == 0 {
a := []interface{}{}
rv := reflect.ValueOf(&a).Elem()
newOffset, err := d.decodeSlice(size, offset, rv, depth)
result.Set(rv)
return newOffset, err
}
}
return 0, newUnmarshalTypeError("array", result.Type())
}
func (d *decoder) unmarshalString(size uint, offset uint, result reflect.Value) (uint, error) {
value, newOffset, err := d.decodeString(size, offset)
if err != nil {
return 0, err
}
switch result.Kind() {
case reflect.String:
result.SetString(value)
return newOffset, nil
case reflect.Interface:
if result.NumMethod() == 0 {
result.Set(reflect.ValueOf(value))
return newOffset, nil
}
}
return newOffset, newUnmarshalTypeError(value, result.Type())
}
func (d *decoder) unmarshalUint(size uint, offset uint, result reflect.Value, uintType uint) (uint, error) {
if size > uintType/8 {
return 0, newInvalidDatabaseError("the MaxMind DB file's data section contains bad data (uint%v size of %v)", uintType, size)
}
value, newOffset, err := d.decodeUint(size, offset)
if err != nil {
return 0, err
}
switch result.Kind() {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
n := int64(value)
if !result.OverflowInt(n) {
result.SetInt(n)
return newOffset, nil
}
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
if !result.OverflowUint(value) {
result.SetUint(value)
return newOffset, nil
}
case reflect.Interface:
if result.NumMethod() == 0 {
result.Set(reflect.ValueOf(value))
return newOffset, nil
}
}
return newOffset, newUnmarshalTypeError(value, result.Type())
}
var bigIntType = reflect.TypeOf(big.Int{})
func (d *decoder) unmarshalUint128(size uint, offset uint, result reflect.Value) (uint, error) {
if size > 16 {
return 0, newInvalidDatabaseError("the MaxMind DB file's data section contains bad data (uint128 size of %v)", size)
}
value, newOffset, err := d.decodeUint128(size, offset)
if err != nil {
return 0, err
}
switch result.Kind() {
case reflect.Struct:
if result.Type() == bigIntType {
result.Set(reflect.ValueOf(*value))
return newOffset, nil
}
case reflect.Interface:
if result.NumMethod() == 0 {
result.Set(reflect.ValueOf(value))
return newOffset, nil
}
}
return newOffset, newUnmarshalTypeError(value, result.Type())
}
func (d *decoder) decodeBool(size uint, offset uint) (bool, uint, error) {
return size != 0, offset, nil
}
func (d *decoder) decodeBytes(size uint, offset uint) ([]byte, uint, error) {
newOffset := offset + size
bytes := make([]byte, size)
copy(bytes, d.buffer[offset:newOffset])
return bytes, newOffset, nil
}
func (d *decoder) decodeFloat64(size uint, offset uint) (float64, uint, error) {
newOffset := offset + size
bits := binary.BigEndian.Uint64(d.buffer[offset:newOffset])
return math.Float64frombits(bits), newOffset, nil
}
func (d *decoder) decodeFloat32(size uint, offset uint) (float32, uint, error) {
newOffset := offset + size
bits := binary.BigEndian.Uint32(d.buffer[offset:newOffset])
return math.Float32frombits(bits), newOffset, nil
}
func (d *decoder) decodeInt(size uint, offset uint) (int, uint, error) {
newOffset := offset + size
var val int32
for _, b := range d.buffer[offset:newOffset] {
val = (val << 8) | int32(b)
}
return int(val), newOffset, nil
}
func (d *decoder) decodeMap(
size uint,
offset uint,
result reflect.Value,
depth int,
) (uint, error) {
if result.IsNil() {
result.Set(reflect.MakeMap(result.Type()))
}
for i := uint(0); i < size; i++ {
var key []byte
var err error
key, offset, err = d.decodeKey(offset)
if err != nil {
return 0, err
}
value := reflect.New(result.Type().Elem())
offset, err = d.decode(offset, value, depth)
if err != nil {
return 0, err
}
result.SetMapIndex(reflect.ValueOf(string(key)), value.Elem())
}
return offset, nil
}
func (d *decoder) decodePointer(
size uint,
offset uint,
) (uint, uint, error) {
pointerSize := ((size >> 3) & 0x3) + 1
newOffset := offset + pointerSize
if newOffset > uint(len(d.buffer)) {
return 0, 0, newOffsetError()
}
pointerBytes := d.buffer[offset:newOffset]
var prefix uint
if pointerSize == 4 {
prefix = 0
} else {
prefix = uint(size & 0x7)
}
unpacked := uintFromBytes(prefix, pointerBytes)
var pointerValueOffset uint
switch pointerSize {
case 1:
pointerValueOffset = 0
case 2:
pointerValueOffset = 2048
case 3:
pointerValueOffset = 526336
case 4:
pointerValueOffset = 0
}
pointer := unpacked + pointerValueOffset
return pointer, newOffset, nil
}
func (d *decoder) decodeSlice(
size uint,
offset uint,
result reflect.Value,
depth int,
) (uint, error) {
result.Set(reflect.MakeSlice(result.Type(), int(size), int(size)))
for i := 0; i < int(size); i++ {
var err error
offset, err = d.decode(offset, result.Index(i), depth)
if err != nil {
return 0, err
}
}
return offset, nil
}
func (d *decoder) decodeString(size uint, offset uint) (string, uint, error) {
newOffset := offset + size
return string(d.buffer[offset:newOffset]), newOffset, nil
}
type fieldsType struct {
namedFields map[string]int
anonymousFields []int
}
var (
fieldMap = map[reflect.Type]*fieldsType{}
fieldMapMu sync.RWMutex
)
func (d *decoder) decodeStruct(
size uint,
offset uint,
result reflect.Value,
depth int,
) (uint, error) {
resultType := result.Type()
fieldMapMu.RLock()
fields, ok := fieldMap[resultType]
fieldMapMu.RUnlock()
if !ok {
numFields := resultType.NumField()
namedFields := make(map[string]int, numFields)
var anonymous []int
for i := 0; i < numFields; i++ {
field := resultType.Field(i)
fieldName := field.Name
if tag := field.Tag.Get("maxminddb"); tag != "" {
if tag == "-" {
continue
}
fieldName = tag
}
if field.Anonymous {
anonymous = append(anonymous, i)
continue
}
namedFields[fieldName] = i
}
fieldMapMu.Lock()
fields = &fieldsType{namedFields, anonymous}
fieldMap[resultType] = fields
fieldMapMu.Unlock()
}
// This fills in embedded structs
for _, i := range fields.anonymousFields {
_, err := d.unmarshalMap(size, offset, result.Field(i), depth)
if err != nil {
return 0, err
}
}
// This handles named fields
for i := uint(0); i < size; i++ {
var (
err error
key []byte
)
key, offset, err = d.decodeKey(offset)
if err != nil {
return 0, err
}
// The string() does not create a copy due to this compiler
// optimization: https://github.com/golang/go/issues/3512
j, ok := fields.namedFields[string(key)]
if !ok {
offset, err = d.nextValueOffset(offset, 1)
if err != nil {
return 0, err
}
continue
}
offset, err = d.decode(offset, result.Field(j), depth)
if err != nil {
return 0, err
}
}
return offset, nil
}
func (d *decoder) decodeUint(size uint, offset uint) (uint64, uint, error) {
newOffset := offset + size
bytes := d.buffer[offset:newOffset]
var val uint64
for _, b := range bytes {
val = (val << 8) | uint64(b)
}
return val, newOffset, nil
}
func (d *decoder) decodeUint128(size uint, offset uint) (*big.Int, uint, error) {
newOffset := offset + size
val := new(big.Int)
val.SetBytes(d.buffer[offset:newOffset])
return val, newOffset, nil
}
func uintFromBytes(prefix uint, uintBytes []byte) uint {
val := prefix
for _, b := range uintBytes {
val = (val << 8) | uint(b)
}
return val
}
// decodeKey decodes a map key into []byte slice. We use a []byte so that we
// can take advantage of https://github.com/golang/go/issues/3512 to avoid
// copying the bytes when decoding a struct. Previously, we achieved this by
// using unsafe.
func (d *decoder) decodeKey(offset uint) ([]byte, uint, error) {
typeNum, size, dataOffset, err := d.decodeCtrlData(offset)
if err != nil {
return nil, 0, err
}
if typeNum == _Pointer {
pointer, ptrOffset, err := d.decodePointer(size, dataOffset)
if err != nil {
return nil, 0, err
}
key, _, err := d.decodeKey(pointer)
return key, ptrOffset, err
}
if typeNum != _String {
return nil, 0, newInvalidDatabaseError("unexpected type when decoding string: %v", typeNum)
}
newOffset := dataOffset + size
if newOffset > uint(len(d.buffer)) {
return nil, 0, newOffsetError()
}
return d.buffer[dataOffset:newOffset], newOffset, nil
}
// This function is used to skip ahead to the next value without decoding
// the one at the offset passed in. The size bits have different meanings for
// different data types
func (d *decoder) nextValueOffset(offset uint, numberToSkip uint) (uint, error) {
if numberToSkip == 0 {
return offset, nil
}
typeNum, size, offset, err := d.decodeCtrlData(offset)
if err != nil {
return 0, err
}
switch typeNum {
case _Pointer:
_, offset, err = d.decodePointer(size, offset)
if err != nil {
return 0, err
}
case _Map:
numberToSkip += 2 * size
case _Slice:
numberToSkip += size
case _Bool:
default:
offset += size
}
return d.nextValueOffset(offset, numberToSkip-1)
}