rlp: new package for streaming RLP decoder

This commit is contained in:
Felix Lange 2014-11-13 20:31:48 +01:00
parent 9509322ecd
commit 74266d5bbd
4 changed files with 1243 additions and 0 deletions

666
rlp/decode.go Normal file
View File

@ -0,0 +1,666 @@
package rlp
import (
"encoding/binary"
"errors"
"fmt"
"io"
"math/big"
"reflect"
)
var (
errNoPointer = errors.New("rlp: interface given to Decode must be a pointer")
errDecodeIntoNil = errors.New("rlp: pointer given to Decode must not be nil")
)
// Decoder is implemented by types that require custom RLP
// decoding rules or need to decode into private fields.
//
// The DecodeRLP method should read one value from the given
// Stream. It is not forbidden to read less or more, but it might
// be confusing.
type Decoder interface {
DecodeRLP(*Stream) error
}
// Decode parses RLP-encoded data from r and stores the result
// in the value pointed to by val. Val must be a non-nil pointer.
//
// Decode uses the following type-dependent decoding rules:
//
// If the type implements the Decoder interface, decode calls
// DecodeRLP.
//
// To decode into a pointer, Decode will set the pointer to nil if the
// input has size zero or the input is a single byte with value zero.
// If the input has nonzero size, Decode will allocate a new value of
// the type being pointed to.
//
// To decode into a struct, Decode expects the input to be an RLP
// list. The decoded elements of the list are assigned to each public
// field in the order given by the struct's definition. If the input
// list has too few elements, no error is returned and the remaining
// fields will have the zero value.
// Recursive struct types are supported.
//
// To decode into a slice, the input must be a list and the resulting
// slice will contain the input elements in order.
// As a special case, if the slice has a byte-size element type, the input
// can also be an RLP string.
//
// To decode into a Go string, the input must be an RLP string. The
// bytes are taken as-is and will not necessarily be valid UTF-8.
//
// To decode into an integer type, the input must also be an RLP
// string. The bytes are interpreted as a big endian representation of
// the integer. If the RLP string is larger than the bit size of the
// type, Decode will return an error. Decode also supports *big.Int.
// There is no size limit for big integers.
//
// To decode into an interface value, Decode stores one of these
// in the value:
//
// []interface{}, for RLP lists
// []byte, for RLP strings
//
// Non-empty interface types are not supported, nor are bool, float32,
// float64, maps, channel types and functions.
func Decode(r ByteReader, val interface{}) error {
return NewStream(r).Decode(val)
}
func makeNumDecoder(typ reflect.Type) decoder {
kind := typ.Kind()
switch {
case kind <= reflect.Int64:
return decodeInt
case kind <= reflect.Uint64:
return decodeUint
default:
panic("fallthrough")
}
}
func decodeInt(s *Stream, val reflect.Value) error {
num, err := s.uint(val.Type().Bits())
if err != nil {
return err
}
val.SetInt(int64(num))
return nil
}
func decodeUint(s *Stream, val reflect.Value) error {
num, err := s.uint(val.Type().Bits())
if err != nil {
return err
}
val.SetUint(num)
return nil
}
func decodeString(s *Stream, val reflect.Value) error {
b, err := s.Bytes()
if err != nil {
return err
}
val.SetString(string(b))
return nil
}
func decodeBigIntNoPtr(s *Stream, val reflect.Value) error {
return decodeBigInt(s, val.Addr())
}
func decodeBigInt(s *Stream, val reflect.Value) error {
b, err := s.Bytes()
if err != nil {
return err
}
i := val.Interface().(*big.Int)
if i == nil {
i = new(big.Int)
val.Set(reflect.ValueOf(i))
}
i.SetBytes(b)
return nil
}
const maxInt = int(^uint(0) >> 1)
func makeListDecoder(typ reflect.Type) (decoder, error) {
etype := typ.Elem()
if etype.Kind() == reflect.Uint8 && !reflect.PtrTo(etype).Implements(decoderInterface) {
if typ.Kind() == reflect.Array {
return decodeByteArray, nil
} else {
return decodeByteSlice, nil
}
}
etypeinfo, err := cachedTypeInfo1(etype)
if err != nil {
return nil, err
}
var maxLen = maxInt
if typ.Kind() == reflect.Array {
maxLen = typ.Len()
}
dec := func(s *Stream, val reflect.Value) error {
return decodeList(s, val, etypeinfo.decoder, maxLen)
}
return dec, nil
}
// decodeList decodes RLP list elements into slices and arrays.
//
// The approach here is stolen from package json, although we differ
// in the semantics for arrays. package json discards remaining
// elements that would not fit into the array. We generate an error in
// this case because we'd be losing information.
func decodeList(s *Stream, val reflect.Value, elemdec decoder, maxelem int) error {
size, err := s.List()
if err != nil {
return err
}
if size == 0 {
if val.Kind() == reflect.Slice {
val.Set(reflect.MakeSlice(val.Type(), 0, 0))
} else {
zero(val, 0)
}
return s.ListEnd()
}
i := 0
for {
if i > maxelem {
return fmt.Errorf("rlp: input List has more than %d elements", maxelem)
}
if val.Kind() == reflect.Slice {
// grow slice if necessary
if i >= val.Cap() {
newcap := val.Cap() + val.Cap()/2
if newcap < 4 {
newcap = 4
}
newv := reflect.MakeSlice(val.Type(), val.Len(), newcap)
reflect.Copy(newv, val)
val.Set(newv)
}
if i >= val.Len() {
val.SetLen(i + 1)
}
}
// decode into element
if err := elemdec(s, val.Index(i)); err == EOL {
break
} else if err != nil {
return err
}
i++
}
if i < val.Len() {
if val.Kind() == reflect.Array {
// zero the rest of the array.
zero(val, i)
} else {
val.SetLen(i)
}
}
return s.ListEnd()
}
func decodeByteSlice(s *Stream, val reflect.Value) error {
kind, _, err := s.Kind()
if err != nil {
return err
}
if kind == List {
return decodeList(s, val, decodeUint, maxInt)
}
b, err := s.Bytes()
if err == nil {
val.SetBytes(b)
}
return err
}
var errStringDoesntFitArray = errors.New("rlp: string value doesn't fit into target array")
func decodeByteArray(s *Stream, val reflect.Value) error {
kind, size, err := s.Kind()
if err != nil {
return err
}
switch kind {
case Byte:
if val.Len() == 0 {
return errStringDoesntFitArray
}
bv, _ := s.Uint()
val.Index(0).SetUint(bv)
zero(val, 1)
case String:
if uint64(val.Len()) < size {
return errStringDoesntFitArray
}
slice := val.Slice(0, int(size)).Interface().([]byte)
if err := s.readFull(slice); err != nil {
return err
}
zero(val, int(size))
case List:
return decodeList(s, val, decodeUint, val.Len())
}
return nil
}
func zero(val reflect.Value, start int) {
z := reflect.Zero(val.Type().Elem())
for i := start; i < val.Len(); i++ {
val.Index(i).Set(z)
}
}
type field struct {
index int
info *typeinfo
}
func makeStructDecoder(typ reflect.Type) (decoder, error) {
var fields []field
for i := 0; i < typ.NumField(); i++ {
if f := typ.Field(i); f.PkgPath == "" { // exported
info, err := cachedTypeInfo1(f.Type)
if err != nil {
return nil, err
}
fields = append(fields, field{i, info})
}
}
dec := func(s *Stream, val reflect.Value) (err error) {
if _, err = s.List(); err != nil {
return err
}
for _, f := range fields {
err = f.info.decoder(s, val.Field(f.index))
if err == EOL {
// too few elements. leave the rest at their zero value.
break
} else if err != nil {
return err
}
}
if err = s.ListEnd(); err == errNotAtEOL {
err = errors.New("rlp: input List has too many elements")
}
return err
}
return dec, nil
}
func makePtrDecoder(typ reflect.Type) (decoder, error) {
etype := typ.Elem()
etypeinfo, err := cachedTypeInfo1(etype)
if err != nil {
return nil, err
}
dec := func(s *Stream, val reflect.Value) (err error) {
_, size, err := s.Kind()
if err != nil || size == 0 && s.byteval == 0 {
return err
}
newval := val
if val.IsNil() {
newval = reflect.New(etype)
}
if err = etypeinfo.decoder(s, newval.Elem()); err == nil {
val.Set(newval)
}
return err
}
return dec, nil
}
var ifsliceType = reflect.TypeOf([]interface{}{})
func decodeInterface(s *Stream, val reflect.Value) error {
kind, _, err := s.Kind()
if err != nil {
return err
}
if kind == List {
slice := reflect.New(ifsliceType).Elem()
if err := decodeList(s, slice, decodeInterface, maxInt); err != nil {
return err
}
val.Set(slice)
} else {
b, err := s.Bytes()
if err != nil {
return err
}
val.Set(reflect.ValueOf(b))
}
return nil
}
// This decoder is used for non-pointer values of types
// that implement the Decoder interface using a pointer receiver.
func decodeDecoderNoPtr(s *Stream, val reflect.Value) error {
return val.Addr().Interface().(Decoder).DecodeRLP(s)
}
func decodeDecoder(s *Stream, val reflect.Value) error {
// Decoder instances are not handled using the pointer rule if the type
// implements Decoder with pointer receiver (i.e. always)
// because it might handle empty values specially.
// We need to allocate one here in this case, like makePtrDecoder does.
if val.Kind() == reflect.Ptr && val.IsNil() {
val.Set(reflect.New(val.Type().Elem()))
}
return val.Interface().(Decoder).DecodeRLP(s)
}
// Kind represents the kind of value contained in an RLP stream.
type Kind int
const (
Byte Kind = iota
String
List
)
func (k Kind) String() string {
switch k {
case Byte:
return "Byte"
case String:
return "String"
case List:
return "List"
default:
return fmt.Sprintf("Unknown(%d)", k)
}
}
var (
// EOL is returned when the end of the current list
// has been reached during streaming.
EOL = errors.New("rlp: end of list")
// Other errors
ErrExpectedString = errors.New("rlp: expected String or Byte")
ErrExpectedList = errors.New("rlp: expected List")
ErrElemTooLarge = errors.New("rlp: element is larger than containing list")
// internal errors
errNotInList = errors.New("rlp: call of ListEnd outside of any list")
errNotAtEOL = errors.New("rlp: call of ListEnd not positioned at EOL")
)
// ByteReader must be implemented by any input reader for a Stream. It
// is implemented by e.g. bufio.Reader and bytes.Reader.
type ByteReader interface {
io.Reader
io.ByteReader
}
// Stream can be used for piecemeal decoding of an input stream. This
// is useful if the input is very large or if the decoding rules for a
// type depend on the input structure. Stream does not keep an
// internal buffer. After decoding a value, the input reader will be
// positioned just before the type information for the next value.
//
// When decoding a list and the input position reaches the declared
// length of the list, all operations will return error EOL.
// The end of the list must be acknowledged using ListEnd to continue
// reading the enclosing list.
//
// Stream is not safe for concurrent use.
type Stream struct {
r ByteReader
uintbuf []byte
kind Kind // kind of value ahead
size uint64 // size of value ahead
byteval byte // value of single byte in type tag
stack []listpos
}
type listpos struct{ pos, size uint64 }
func NewStream(r ByteReader) *Stream {
return &Stream{r: r, uintbuf: make([]byte, 8), kind: -1}
}
// Bytes reads an RLP string and returns its contents as a byte slice.
// If the input does not contain an RLP string, the returned
// error will be ErrExpectedString.
func (s *Stream) Bytes() ([]byte, error) {
kind, size, err := s.Kind()
if err != nil {
return nil, err
}
switch kind {
case Byte:
s.kind = -1 // rearm Kind
return []byte{s.byteval}, nil
case String:
b := make([]byte, size)
if err = s.readFull(b); err != nil {
return nil, err
}
return b, nil
default:
return nil, ErrExpectedString
}
}
// Uint reads an RLP string of up to 8 bytes and returns its contents
// as an unsigned integer. If the input does not contain an RLP string, the
// returned error will be ErrExpectedString.
func (s *Stream) Uint() (uint64, error) {
return s.uint(64)
}
func (s *Stream) uint(maxbits int) (uint64, error) {
kind, size, err := s.Kind()
if err != nil {
return 0, err
}
switch kind {
case Byte:
s.kind = -1 // rearm Kind
return uint64(s.byteval), nil
case String:
if size > uint64(maxbits/8) {
return 0, fmt.Errorf("rlp: string is larger than %d bits", maxbits)
}
return s.readUint(byte(size))
default:
return 0, ErrExpectedString
}
}
// List starts decoding an RLP list. If the input does not contain a
// list, the returned error will be ErrExpectedList. When the list's
// end has been reached, any Stream operation will return EOL.
func (s *Stream) List() (size uint64, err error) {
kind, size, err := s.Kind()
if err != nil {
return 0, err
}
if kind != List {
return 0, ErrExpectedList
}
s.stack = append(s.stack, listpos{0, size})
s.kind = -1
s.size = 0
return size, nil
}
// ListEnd returns to the enclosing list.
// The input reader must be positioned at the end of a list.
func (s *Stream) ListEnd() error {
if len(s.stack) == 0 {
return errNotInList
}
tos := s.stack[len(s.stack)-1]
if tos.pos != tos.size {
return errNotAtEOL
}
s.stack = s.stack[:len(s.stack)-1] // pop
if len(s.stack) > 0 {
s.stack[len(s.stack)-1].pos += tos.size
}
s.kind = -1
s.size = 0
return nil
}
// Decode decodes a value and stores the result in the value pointed
// to by val. Please see the documentation for the Decode function
// to learn about the decoding rules.
func (s *Stream) Decode(val interface{}) error {
if val == nil {
return errDecodeIntoNil
}
rval := reflect.ValueOf(val)
rtyp := rval.Type()
if rtyp.Kind() != reflect.Ptr {
return errNoPointer
}
if rval.IsNil() {
return errDecodeIntoNil
}
info, err := cachedTypeInfo(rtyp.Elem())
if err != nil {
return err
}
return info.decoder(s, rval.Elem())
}
// Kind returns the kind and size of the next value in the
// input stream.
//
// The returned size is the number of bytes that make up the value.
// For kind == Byte, the size is zero because the value is
// contained in the type tag.
//
// The first call to Kind will read size information from the input
// reader and leave it positioned at the start of the actual bytes of
// the value. Subsequent calls to Kind (until the value is decoded)
// will not advance the input reader and return cached information.
func (s *Stream) Kind() (kind Kind, size uint64, err error) {
var tos *listpos
if len(s.stack) > 0 {
tos = &s.stack[len(s.stack)-1]
}
if s.kind < 0 {
if tos != nil && tos.pos == tos.size {
return 0, 0, EOL
}
kind, size, err = s.readKind()
if err != nil {
return 0, 0, err
}
s.kind, s.size = kind, size
}
if tos != nil && tos.pos+s.size > tos.size {
return 0, 0, ErrElemTooLarge
}
return s.kind, s.size, nil
}
func (s *Stream) readKind() (kind Kind, size uint64, err error) {
b, err := s.readByte()
if err != nil {
return 0, 0, err
}
s.byteval = 0
switch {
case b < 0x80:
// For a single byte whose value is in the [0x00, 0x7F] range, that byte
// is its own RLP encoding.
s.byteval = b
return Byte, 0, nil
case b < 0xB8:
// Otherwise, if a string is 0-55 bytes long,
// the RLP encoding consists of a single byte with value 0x80 plus the
// length of the string followed by the string. The range of the first
// byte is thus [0x80, 0xB7].
return String, uint64(b - 0x80), nil
case b < 0xC0:
// If a string is more than 55 bytes long, the
// RLP encoding consists of a single byte with value 0xB7 plus the length
// of the length of the string in binary form, followed by the length of
// the string, followed by the string. For example, a length-1024 string
// would be encoded as 0xB90400 followed by the string. The range of
// the first byte is thus [0xB8, 0xBF].
size, err = s.readUint(b - 0xB7)
return String, size, err
case b < 0xF8:
// If the total payload of a list
// (i.e. the combined length of all its items) is 0-55 bytes long, the
// RLP encoding consists of a single byte with value 0xC0 plus the length
// of the list followed by the concatenation of the RLP encodings of the
// items. The range of the first byte is thus [0xC0, 0xF7].
return List, uint64(b - 0xC0), nil
default:
// If the total payload of a list is more than 55 bytes long,
// the RLP encoding consists of a single byte with value 0xF7
// plus the length of the length of the payload in binary
// form, followed by the length of the payload, followed by
// the concatenation of the RLP encodings of the items. The
// range of the first byte is thus [0xF8, 0xFF].
size, err = s.readUint(b - 0xF7)
return List, size, err
}
}
func (s *Stream) readUint(size byte) (uint64, error) {
if size == 1 {
b, err := s.readByte()
if err == io.EOF {
err = io.ErrUnexpectedEOF
}
return uint64(b), err
}
start := int(8 - size)
for i := 0; i < start; i++ {
s.uintbuf[i] = 0
}
err := s.readFull(s.uintbuf[start:])
return binary.BigEndian.Uint64(s.uintbuf), err
}
func (s *Stream) readFull(buf []byte) (err error) {
s.willRead(uint64(len(buf)))
var nn, n int
for n < len(buf) && err == nil {
nn, err = s.r.Read(buf[n:])
n += nn
}
if err == io.EOF {
err = io.ErrUnexpectedEOF
}
return err
}
func (s *Stream) readByte() (byte, error) {
s.willRead(1)
b, err := s.r.ReadByte()
if len(s.stack) > 0 && err == io.EOF {
err = io.ErrUnexpectedEOF
}
return b, err
}
func (s *Stream) willRead(n uint64) {
s.kind = -1 // rearm Kind
if len(s.stack) > 0 {
s.stack[len(s.stack)-1].pos += n
}
}

469
rlp/decode_test.go Normal file
View File

@ -0,0 +1,469 @@
package rlp
import (
"bytes"
"encoding/hex"
"errors"
"fmt"
"io"
"math/big"
"reflect"
"testing"
"github.com/ethereum/go-ethereum/ethutil"
)
func TestStreamKind(t *testing.T) {
tests := []struct {
input string
wantKind Kind
wantLen uint64
}{
{"00", Byte, 0},
{"01", Byte, 0},
{"7F", Byte, 0},
{"80", String, 0},
{"B7", String, 55},
{"B800", String, 0},
{"B90400", String, 1024},
{"BA000400", String, 1024},
{"BB00000400", String, 1024},
{"BFFFFFFFFFFFFFFFFF", String, ^uint64(0)},
{"C0", List, 0},
{"C8", List, 8},
{"F7", List, 55},
{"F800", List, 0},
{"F804", List, 4},
{"F90400", List, 1024},
{"FFFFFFFFFFFFFFFFFF", List, ^uint64(0)},
}
for i, test := range tests {
s := NewStream(bytes.NewReader(unhex(test.input)))
kind, len, err := s.Kind()
if err != nil {
t.Errorf("test %d: Type returned error: %v", i, err)
continue
}
if kind != test.wantKind {
t.Errorf("test %d: kind mismatch: got %d, want %d", i, kind, test.wantKind)
}
if len != test.wantLen {
t.Errorf("test %d: len mismatch: got %d, want %d", i, len, test.wantLen)
}
}
}
func TestStreamErrors(t *testing.T) {
type calls []string
tests := []struct {
string
calls
error
}{
{"", calls{"Kind"}, io.EOF},
{"", calls{"List"}, io.EOF},
{"", calls{"Uint"}, io.EOF},
{"C0", calls{"Bytes"}, ErrExpectedString},
{"C0", calls{"Uint"}, ErrExpectedString},
{"81", calls{"Bytes"}, io.ErrUnexpectedEOF},
{"81", calls{"Uint"}, io.ErrUnexpectedEOF},
{"BFFFFFFFFFFFFFFF", calls{"Bytes"}, io.ErrUnexpectedEOF},
{"89000000000000000001", calls{"Uint"}, errors.New("rlp: string is larger than 64 bits")},
{"00", calls{"List"}, ErrExpectedList},
{"80", calls{"List"}, ErrExpectedList},
{"C0", calls{"List", "Uint"}, EOL},
{"C801", calls{"List", "Uint", "Uint"}, io.ErrUnexpectedEOF},
{"C8C9", calls{"List", "Kind"}, ErrElemTooLarge},
{"C3C2010201", calls{"List", "List", "Uint", "Uint", "ListEnd", "Uint"}, EOL},
{"00", calls{"ListEnd"}, errNotInList},
{"C40102", calls{"List", "Uint", "ListEnd"}, errNotAtEOL},
}
testfor:
for i, test := range tests {
s := NewStream(bytes.NewReader(unhex(test.string)))
rs := reflect.ValueOf(s)
for j, call := range test.calls {
fval := rs.MethodByName(call)
ret := fval.Call(nil)
err := "<nil>"
if lastret := ret[len(ret)-1].Interface(); lastret != nil {
err = lastret.(error).Error()
}
if j == len(test.calls)-1 {
if err != test.error.Error() {
t.Errorf("test %d: last call (%s) error mismatch\ngot: %s\nwant: %v",
i, call, err, test.error)
}
} else if err != "<nil>" {
t.Errorf("test %d: call %d (%s) unexpected error: %q", i, j, call, err)
continue testfor
}
}
}
}
func TestStreamList(t *testing.T) {
s := NewStream(bytes.NewReader(unhex("C80102030405060708")))
len, err := s.List()
if err != nil {
t.Fatalf("List error: %v", err)
}
if len != 8 {
t.Fatalf("List returned invalid length, got %d, want 8", len)
}
for i := uint64(1); i <= 8; i++ {
v, err := s.Uint()
if err != nil {
t.Fatalf("Uint error: %v", err)
}
if i != v {
t.Errorf("Uint returned wrong value, got %d, want %d", v, i)
}
}
if _, err := s.Uint(); err != EOL {
t.Errorf("Uint error mismatch, got %v, want %v", err, EOL)
}
if err = s.ListEnd(); err != nil {
t.Fatalf("ListEnd error: %v", err)
}
}
func TestDecodeErrors(t *testing.T) {
r := bytes.NewReader(nil)
if err := Decode(r, nil); err != errDecodeIntoNil {
t.Errorf("Decode(r, nil) error mismatch, got %q, want %q", err, errDecodeIntoNil)
}
var nilptr *struct{}
if err := Decode(r, nilptr); err != errDecodeIntoNil {
t.Errorf("Decode(r, nilptr) error mismatch, got %q, want %q", err, errDecodeIntoNil)
}
if err := Decode(r, struct{}{}); err != errNoPointer {
t.Errorf("Decode(r, struct{}{}) error mismatch, got %q, want %q", err, errNoPointer)
}
expectErr := "rlp: type chan bool is not RLP-serializable"
if err := Decode(r, new(chan bool)); err == nil || err.Error() != expectErr {
t.Errorf("Decode(r, new(chan bool)) error mismatch, got %q, want %q", err, expectErr)
}
if err := Decode(r, new(int)); err != io.EOF {
t.Errorf("Decode(r, new(int)) error mismatch, got %q, want %q", err, io.EOF)
}
}
type decodeTest struct {
input string
ptr interface{}
value interface{}
error error
}
type simplestruct struct {
A int
B string
}
type recstruct struct {
I int
Child *recstruct
}
var sharedByteArray [5]byte
var (
veryBigInt = big.NewInt(0).Add(
big.NewInt(0).Lsh(big.NewInt(0xFFFFFFFFFFFFFF), 16),
big.NewInt(0xFFFF),
)
)
var decodeTests = []decodeTest{
// integers
{input: "05", ptr: new(uint32), value: uint32(5)},
{input: "80", ptr: new(uint32), value: uint32(0)},
{input: "8105", ptr: new(uint32), value: uint32(5)},
{input: "820505", ptr: new(uint32), value: uint32(0x0505)},
{input: "83050505", ptr: new(uint32), value: uint32(0x050505)},
{input: "8405050505", ptr: new(uint32), value: uint32(0x05050505)},
{input: "850505050505", ptr: new(uint32), error: errors.New("rlp: string is larger than 32 bits")},
{input: "C0", ptr: new(uint32), error: ErrExpectedString},
// slices
{input: "C0", ptr: new([]int), value: []int{}},
{input: "C80102030405060708", ptr: new([]int), value: []int{1, 2, 3, 4, 5, 6, 7, 8}},
// arrays
{input: "C0", ptr: new([5]int), value: [5]int{}},
{input: "C50102030405", ptr: new([5]int), value: [5]int{1, 2, 3, 4, 5}},
{input: "C6010203040506", ptr: new([5]int), error: errors.New("rlp: input List has more than 5 elements")},
// byte slices
{input: "01", ptr: new([]byte), value: []byte{1}},
{input: "80", ptr: new([]byte), value: []byte{}},
{input: "8D6162636465666768696A6B6C6D", ptr: new([]byte), value: []byte("abcdefghijklm")},
{input: "C0", ptr: new([]byte), value: []byte{}},
{input: "C3010203", ptr: new([]byte), value: []byte{1, 2, 3}},
{input: "C3820102", ptr: new([]byte), error: errors.New("rlp: string is larger than 8 bits")},
// byte arrays
{input: "01", ptr: new([5]byte), value: [5]byte{1}},
{input: "80", ptr: new([5]byte), value: [5]byte{}},
{input: "850102030405", ptr: new([5]byte), value: [5]byte{1, 2, 3, 4, 5}},
{input: "C0", ptr: new([5]byte), value: [5]byte{}},
{input: "C3010203", ptr: new([5]byte), value: [5]byte{1, 2, 3, 0, 0}},
{input: "C3820102", ptr: new([5]byte), error: errors.New("rlp: string is larger than 8 bits")},
{input: "86010203040506", ptr: new([5]byte), error: errStringDoesntFitArray},
{input: "850101", ptr: new([5]byte), error: io.ErrUnexpectedEOF},
// byte array reuse (should be zeroed)
{input: "850102030405", ptr: &sharedByteArray, value: [5]byte{1, 2, 3, 4, 5}},
{input: "8101", ptr: &sharedByteArray, value: [5]byte{1}}, // kind: String
{input: "850102030405", ptr: &sharedByteArray, value: [5]byte{1, 2, 3, 4, 5}},
{input: "01", ptr: &sharedByteArray, value: [5]byte{1}}, // kind: Byte
{input: "C3010203", ptr: &sharedByteArray, value: [5]byte{1, 2, 3, 0, 0}},
{input: "C101", ptr: &sharedByteArray, value: [5]byte{1}}, // kind: List
// zero sized byte arrays
{input: "80", ptr: new([0]byte), value: [0]byte{}},
{input: "C0", ptr: new([0]byte), value: [0]byte{}},
{input: "01", ptr: new([0]byte), error: errStringDoesntFitArray},
{input: "8101", ptr: new([0]byte), error: errStringDoesntFitArray},
// strings
{input: "00", ptr: new(string), value: "\000"},
{input: "8D6162636465666768696A6B6C6D", ptr: new(string), value: "abcdefghijklm"},
{input: "C0", ptr: new(string), error: ErrExpectedString},
// big ints
{input: "01", ptr: new(*big.Int), value: big.NewInt(1)},
{input: "89FFFFFFFFFFFFFFFFFF", ptr: new(*big.Int), value: veryBigInt},
{input: "10", ptr: new(big.Int), value: *big.NewInt(16)}, // non-pointer also works
{input: "C0", ptr: new(*big.Int), error: ErrExpectedString},
// structs
{input: "C0", ptr: new(simplestruct), value: simplestruct{0, ""}},
{input: "C105", ptr: new(simplestruct), value: simplestruct{5, ""}},
{input: "C50583343434", ptr: new(simplestruct), value: simplestruct{5, "444"}},
{input: "C3010101", ptr: new(simplestruct), error: errors.New("rlp: input List has too many elements")},
{
input: "C501C302C103",
ptr: new(recstruct),
value: recstruct{1, &recstruct{2, &recstruct{3, nil}}},
},
// pointers
{input: "00", ptr: new(*int), value: (*int)(nil)},
{input: "80", ptr: new(*int), value: (*int)(nil)},
{input: "C0", ptr: new(*int), value: (*int)(nil)},
{input: "07", ptr: new(*int), value: intp(7)},
{input: "8108", ptr: new(*int), value: intp(8)},
{input: "C109", ptr: new(*[]int), value: &[]int{9}},
{input: "C58403030303", ptr: new(*[][]byte), value: &[][]byte{{3, 3, 3, 3}}},
// interface{}
{input: "00", ptr: new(interface{}), value: []byte{0}},
{input: "01", ptr: new(interface{}), value: []byte{1}},
{input: "80", ptr: new(interface{}), value: []byte{}},
{input: "850505050505", ptr: new(interface{}), value: []byte{5, 5, 5, 5, 5}},
{input: "C0", ptr: new(interface{}), value: []interface{}{}},
{input: "C50183040404", ptr: new(interface{}), value: []interface{}{[]byte{1}, []byte{4, 4, 4}}},
}
func intp(i int) *int { return &i }
func TestDecode(t *testing.T) {
for i, test := range decodeTests {
input, err := hex.DecodeString(test.input)
if err != nil {
t.Errorf("test %d: invalid hex input %q", i, test.input)
continue
}
err = Decode(bytes.NewReader(input), test.ptr)
if err != nil && test.error == nil {
t.Errorf("test %d: unexpected Decode error: %v\ndecoding into %T\ninput %q",
i, err, test.ptr, test.input)
continue
}
if test.error != nil && fmt.Sprint(err) != fmt.Sprint(test.error) {
t.Errorf("test %d: Decode error mismatch\ngot %v\nwant %v\ndecoding into %T\ninput %q",
i, err, test.error, test.ptr, test.input)
continue
}
deref := reflect.ValueOf(test.ptr).Elem().Interface()
if err == nil && !reflect.DeepEqual(deref, test.value) {
t.Errorf("test %d: value mismatch\ngot %#v\nwant %#v\ndecoding into %T\ninput %q",
i, deref, test.value, test.ptr, test.input)
}
}
}
type testDecoder struct{ called bool }
func (t *testDecoder) DecodeRLP(s *Stream) error {
if _, err := s.Uint(); err != nil {
return err
}
t.called = true
return nil
}
func TestDecodeDecoder(t *testing.T) {
var s struct {
T1 testDecoder
T2 *testDecoder
T3 **testDecoder
}
if err := Decode(bytes.NewReader(unhex("C3010203")), &s); err != nil {
t.Fatalf("Decode error: %v", err)
}
if !s.T1.called {
t.Errorf("DecodeRLP was not called for (non-pointer) testDecoder")
}
if s.T2 == nil {
t.Errorf("*testDecoder has not been allocated")
} else if !s.T2.called {
t.Errorf("DecodeRLP was not called for *testDecoder")
}
if s.T3 == nil || *s.T3 == nil {
t.Errorf("**testDecoder has not been allocated")
} else if !(*s.T3).called {
t.Errorf("DecodeRLP was not called for **testDecoder")
}
}
type byteDecoder byte
func (bd *byteDecoder) DecodeRLP(s *Stream) error {
_, err := s.Uint()
*bd = 255
return err
}
func (bd byteDecoder) called() bool {
return bd == 255
}
// This test verifies that the byte slice/byte array logic
// does not kick in for element types implementing Decoder.
func TestDecoderInByteSlice(t *testing.T) {
var slice []byteDecoder
if err := Decode(bytes.NewReader(unhex("C101")), &slice); err != nil {
t.Errorf("unexpected Decode error %v", err)
} else if !slice[0].called() {
t.Errorf("DecodeRLP not called for slice element")
}
var array [1]byteDecoder
if err := Decode(bytes.NewReader(unhex("C101")), &array); err != nil {
t.Errorf("unexpected Decode error %v", err)
} else if !array[0].called() {
t.Errorf("DecodeRLP not called for array element")
}
}
func ExampleDecode() {
input, _ := hex.DecodeString("C90A1486666F6F626172")
type example struct {
A, B int
private int // private fields are ignored
String string
}
var s example
err := Decode(bytes.NewReader(input), &s)
if err != nil {
fmt.Printf("Error: %v\n", err)
} else {
fmt.Printf("Decoded value: %#v\n", s)
}
// Output:
// Decoded value: rlp.example{A:10, B:20, private:0, String:"foobar"}
}
func ExampleStream() {
input, _ := hex.DecodeString("C90A1486666F6F626172")
s := NewStream(bytes.NewReader(input))
// Check what kind of value lies ahead
kind, size, _ := s.Kind()
fmt.Printf("Kind: %v size:%d\n", kind, size)
// Enter the list
if _, err := s.List(); err != nil {
fmt.Printf("List error: %v\n", err)
return
}
// Decode elements
fmt.Println(s.Uint())
fmt.Println(s.Uint())
fmt.Println(s.Bytes())
// Acknowledge end of list
if err := s.ListEnd(); err != nil {
fmt.Printf("ListEnd error: %v\n", err)
}
// Output:
// Kind: List size:9
// 10 <nil>
// 20 <nil>
// [102 111 111 98 97 114] <nil>
}
func BenchmarkDecode(b *testing.B) {
enc := encTest(90000)
b.SetBytes(int64(len(enc)))
b.ReportAllocs()
b.ResetTimer()
for i := 0; i < b.N; i++ {
var s []int
r := bytes.NewReader(enc)
if err := Decode(r, &s); err != nil {
b.Fatalf("Decode error: %v", err)
}
}
}
func BenchmarkDecodeIntSliceReuse(b *testing.B) {
enc := encTest(100000)
b.SetBytes(int64(len(enc)))
b.ReportAllocs()
b.ResetTimer()
var s []int
for i := 0; i < b.N; i++ {
r := bytes.NewReader(enc)
if err := Decode(r, &s); err != nil {
b.Fatalf("Decode error: %v", err)
}
}
}
func encTest(n int) []byte {
s := make([]interface{}, n)
for i := 0; i < n; i++ {
s[i] = i
}
return ethutil.Encode(s)
}
func unhex(str string) []byte {
b, err := hex.DecodeString(str)
if err != nil {
panic(fmt.Sprintf("invalid hex string: %q", str))
}
return b
}

17
rlp/doc.go Normal file
View File

@ -0,0 +1,17 @@
/*
Package rlp implements the RLP serialization format.
The purpose of RLP (Recursive Linear Prefix) qis to encode arbitrarily
nested arrays of binary data, and RLP is the main encoding method used
to serialize objects in Ethereum. The only purpose of RLP is to encode
structure; encoding specific atomic data types (eg. strings, ints,
floats) is left up to higher-order protocols; in Ethereum integers
must be represented in big endian binary form with no leading zeroes
(thus making the integer value zero be equivalent to the empty byte
array).
RLP values are distinguished by a type tag. The type tag precedes the
value in the input stream and defines the size and kind of the bytes
that follow.
*/
package rlp

91
rlp/typecache.go Normal file
View File

@ -0,0 +1,91 @@
package rlp
import (
"fmt"
"math/big"
"reflect"
"sync"
)
type decoder func(*Stream, reflect.Value) error
type typeinfo struct {
decoder
}
var (
typeCacheMutex sync.RWMutex
typeCache = make(map[reflect.Type]*typeinfo)
)
func cachedTypeInfo(typ reflect.Type) (*typeinfo, error) {
typeCacheMutex.RLock()
info := typeCache[typ]
typeCacheMutex.RUnlock()
if info != nil {
return info, nil
}
// not in the cache, need to generate info for this type.
typeCacheMutex.Lock()
defer typeCacheMutex.Unlock()
return cachedTypeInfo1(typ)
}
func cachedTypeInfo1(typ reflect.Type) (*typeinfo, error) {
info := typeCache[typ]
if info != nil {
// another goroutine got the write lock first
return info, nil
}
// put a dummmy value into the cache before generating.
// if the generator tries to lookup itself, it will get
// the dummy value and won't call itself recursively.
typeCache[typ] = new(typeinfo)
info, err := genTypeInfo(typ)
if err != nil {
// remove the dummy value if the generator fails
delete(typeCache, typ)
return nil, err
}
*typeCache[typ] = *info
return typeCache[typ], err
}
var (
decoderInterface = reflect.TypeOf(new(Decoder)).Elem()
bigInt = reflect.TypeOf(big.Int{})
)
func genTypeInfo(typ reflect.Type) (info *typeinfo, err error) {
info = new(typeinfo)
kind := typ.Kind()
switch {
case typ.Implements(decoderInterface):
info.decoder = decodeDecoder
case kind != reflect.Ptr && reflect.PtrTo(typ).Implements(decoderInterface):
info.decoder = decodeDecoderNoPtr
case typ.AssignableTo(reflect.PtrTo(bigInt)):
info.decoder = decodeBigInt
case typ.AssignableTo(bigInt):
info.decoder = decodeBigIntNoPtr
case isInteger(kind):
info.decoder = makeNumDecoder(typ)
case kind == reflect.String:
info.decoder = decodeString
case kind == reflect.Slice || kind == reflect.Array:
info.decoder, err = makeListDecoder(typ)
case kind == reflect.Struct:
info.decoder, err = makeStructDecoder(typ)
case kind == reflect.Ptr:
info.decoder, err = makePtrDecoder(typ)
case kind == reflect.Interface && typ.NumMethod() == 0:
info.decoder = decodeInterface
default:
err = fmt.Errorf("rlp: type %v is not RLP-serializable", typ)
}
return info, err
}
func isInteger(k reflect.Kind) bool {
return k >= reflect.Int && k <= reflect.Uintptr
}