rlp: stricter validation of canonical integer format
All integers (including size information in type tags) need to be
encoded using the smallest possible encoding. This commit expands the
stricter validation introduced for *big.Int in commit 59597d23a5
to all integer types and size tags.
This commit is contained in:
Felix Lange
parent
6788f955c2
commit
6e9f8035a1
@ -109,7 +109,9 @@ func (err *decodeError) Error() string {
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func wrapStreamError(err error, typ reflect.Type) error {
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switch err {
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case ErrCanonInt:
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return &decodeError{msg: "canon int error appends zero's", typ: typ}
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return &decodeError{msg: "non-canonical integer (leading zero bytes)", typ: typ}
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case ErrCanonSize:
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return &decodeError{msg: "non-canonical size information", typ: typ}
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case ErrExpectedList:
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return &decodeError{msg: "expected input list", typ: typ}
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case ErrExpectedString:
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@ -195,12 +197,10 @@ func decodeBigInt(s *Stream, val reflect.Value) error {
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i = new(big.Int)
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val.Set(reflect.ValueOf(i))
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}
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// Reject big integers which are zero appended
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// Reject leading zero bytes
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if len(b) > 0 && b[0] == 0 {
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return wrapStreamError(ErrCanonInt, val.Type())
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}
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i.SetBytes(b)
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return nil
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}
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@ -270,7 +270,7 @@ func decodeListSlice(s *Stream, val reflect.Value, elemdec decoder) error {
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func decodeListArray(s *Stream, val reflect.Value, elemdec decoder) error {
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size, err := s.List()
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if err != nil {
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return err
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return wrapStreamError(err, val.Type())
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}
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if size == 0 {
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zero(val, 0)
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@ -474,10 +474,11 @@ var (
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// has been reached during streaming.
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EOL = errors.New("rlp: end of list")
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// Other errors
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// Actual Errors
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ErrExpectedString = errors.New("rlp: expected String or Byte")
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ErrExpectedList = errors.New("rlp: expected List")
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ErrCanonInt = errors.New("rlp: expected Int")
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ErrCanonInt = errors.New("rlp: non-canonical (leading zero bytes) integer")
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ErrCanonSize = errors.New("rlp: non-canonical size information")
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ErrElemTooLarge = errors.New("rlp: element is larger than containing list")
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ErrValueTooLarge = errors.New("rlp: value size exceeds available input length")
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@ -519,6 +520,7 @@ type Stream struct {
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kind Kind // kind of value ahead
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size uint64 // size of value ahead
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byteval byte // value of single byte in type tag
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kinderr error // error from last readKind
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stack []listpos
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}
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@ -619,13 +621,21 @@ func (s *Stream) uint(maxbits int) (uint64, error) {
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}
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switch kind {
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case Byte:
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if s.byteval == 0 {
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return 0, ErrCanonInt
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}
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s.kind = -1 // rearm Kind
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return uint64(s.byteval), nil
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case String:
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if size > uint64(maxbits/8) {
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return 0, errUintOverflow
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}
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return s.readUint(byte(size))
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v, err := s.readUint(byte(size))
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if err == ErrCanonSize {
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// Adjust error because we're not reading a size right now.
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err = ErrCanonInt
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}
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return v, err
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default:
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return 0, ErrExpectedString
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}
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@ -729,6 +739,7 @@ func (s *Stream) Reset(r io.Reader, inputLimit uint64) {
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s.stack = s.stack[:0]
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s.size = 0
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s.kind = -1
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s.kinderr = nil
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if s.uintbuf == nil {
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s.uintbuf = make([]byte, 8)
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}
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@ -751,32 +762,31 @@ func (s *Stream) Kind() (kind Kind, size uint64, err error) {
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tos = &s.stack[len(s.stack)-1]
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}
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if s.kind < 0 {
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s.kinderr = nil
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// Don't read further if we're at the end of the
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// innermost list.
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if tos != nil && tos.pos == tos.size {
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return 0, 0, EOL
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}
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kind, size, err = s.readKind()
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if err != nil {
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return 0, 0, err
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}
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s.kind, s.size = kind, size
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}
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// Make sure size is reasonable. This is done always
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// so Kind returns the same error when called multiple times.
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if tos == nil {
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// At toplevel, check that the value is smaller
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// than the remaining input length.
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if s.limited && s.size > s.remaining {
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return 0, 0, ErrValueTooLarge
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}
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} else {
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// Inside a list, check that the value doesn't overflow the list.
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if s.size > tos.size-tos.pos {
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return 0, 0, ErrElemTooLarge
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s.kind, s.size, s.kinderr = s.readKind()
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if s.kinderr == nil {
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if tos == nil {
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// At toplevel, check that the value is smaller
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// than the remaining input length.
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if s.limited && s.size > s.remaining {
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s.kinderr = ErrValueTooLarge
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}
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} else {
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// Inside a list, check that the value doesn't overflow the list.
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if s.size > tos.size-tos.pos {
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s.kinderr = ErrElemTooLarge
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}
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}
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}
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}
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return s.kind, s.size, nil
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// Note: this might return a sticky error generated
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// by an earlier call to readKind.
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return s.kind, s.size, s.kinderr
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}
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func (s *Stream) readKind() (kind Kind, size uint64, err error) {
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@ -805,6 +815,9 @@ func (s *Stream) readKind() (kind Kind, size uint64, err error) {
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// would be encoded as 0xB90400 followed by the string. The range of
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// the first byte is thus [0xB8, 0xBF].
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size, err = s.readUint(b - 0xB7)
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if err == nil && size < 56 {
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err = ErrCanonSize
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}
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return String, size, err
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case b < 0xF8:
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// If the total payload of a list
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@ -821,24 +834,40 @@ func (s *Stream) readKind() (kind Kind, size uint64, err error) {
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// the concatenation of the RLP encodings of the items. The
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// range of the first byte is thus [0xF8, 0xFF].
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size, err = s.readUint(b - 0xF7)
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if err == nil && size < 56 {
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err = ErrCanonSize
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}
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return List, size, err
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}
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}
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func (s *Stream) readUint(size byte) (uint64, error) {
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if size == 1 {
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switch size {
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case 0:
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s.kind = -1 // rearm Kind
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return 0, nil
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case 1:
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b, err := s.readByte()
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if err == io.EOF {
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err = io.ErrUnexpectedEOF
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}
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return uint64(b), err
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default:
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start := int(8 - size)
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for i := 0; i < start; i++ {
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s.uintbuf[i] = 0
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}
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if err := s.readFull(s.uintbuf[start:]); err != nil {
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return 0, err
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}
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if s.uintbuf[start] == 0 {
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// Note: readUint is also used to decode integer
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// values. The error needs to be adjusted to become
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// ErrCanonInt in this case.
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return 0, ErrCanonSize
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}
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return binary.BigEndian.Uint64(s.uintbuf), nil
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}
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start := int(8 - size)
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for i := 0; i < start; i++ {
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s.uintbuf[i] = 0
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}
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err := s.readFull(s.uintbuf[start:])
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return binary.BigEndian.Uint64(s.uintbuf), err
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}
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func (s *Stream) readFull(buf []byte) (err error) {
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@ -21,16 +21,11 @@ func TestStreamKind(t *testing.T) {
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{"7F", Byte, 0},
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{"80", String, 0},
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{"B7", String, 55},
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{"B800", String, 0},
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{"B90400", String, 1024},
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{"BA000400", String, 1024},
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{"BB00000400", String, 1024},
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{"BFFFFFFFFFFFFFFFFF", String, ^uint64(0)},
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{"C0", List, 0},
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{"C8", List, 8},
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{"F7", List, 55},
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{"F800", List, 0},
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{"F804", List, 4},
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{"F90400", List, 1024},
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{"FFFFFFFFFFFFFFFFFF", List, ^uint64(0)},
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}
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@ -85,7 +80,7 @@ func TestStreamErrors(t *testing.T) {
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string
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calls
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newStream func([]byte) *Stream // uses bytes.Reader if nil
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error
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error error
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}{
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{"C0", calls{"Bytes"}, nil, ErrExpectedString},
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{"C0", calls{"Uint"}, nil, ErrExpectedString},
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@ -98,6 +93,21 @@ func TestStreamErrors(t *testing.T) {
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{"00", calls{"ListEnd"}, nil, errNotInList},
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{"C401020304", calls{"List", "Uint", "ListEnd"}, nil, errNotAtEOL},
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// Leading zero bytes are rejected when reading integers.
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{"00", calls{"Uint"}, nil, ErrCanonInt},
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{"820002", calls{"Uint"}, nil, ErrCanonInt},
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// Size tags must use the smallest possible encoding.
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// Leading zero bytes in the size tag are also rejected.
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{"B800", calls{"Kind"}, withoutInputLimit, ErrCanonSize},
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{"B90000", calls{"Kind"}, withoutInputLimit, ErrCanonSize},
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{"B90055", calls{"Kind"}, withoutInputLimit, ErrCanonSize},
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{"BA0002FFFF", calls{"Bytes"}, withoutInputLimit, ErrCanonSize},
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{"F800", calls{"Kind"}, withoutInputLimit, ErrCanonSize},
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{"F90000", calls{"Kind"}, withoutInputLimit, ErrCanonSize},
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{"F90055", calls{"Kind"}, withoutInputLimit, ErrCanonSize},
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{"FA0002FFFF", calls{"List"}, withoutInputLimit, ErrCanonSize},
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// Expected EOF
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{"", calls{"Kind"}, nil, io.EOF},
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{"", calls{"Uint"}, nil, io.EOF},
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@ -170,10 +180,12 @@ testfor:
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want = test.error.Error()
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}
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if err != want {
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t.Log(test)
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t.Errorf("test %d: last call (%s) error mismatch\ngot: %s\nwant: %s",
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i, call, err, test.error)
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}
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} else if err != "<nil>" {
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t.Log(test)
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t.Errorf("test %d: call %d (%s) unexpected error: %q", i, j, call, err)
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continue testfor
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}
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@ -289,15 +301,20 @@ var decodeTests = []decodeTest{
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{input: "8405050505", ptr: new(uint32), value: uint32(0x05050505)},
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{input: "850505050505", ptr: new(uint32), error: "rlp: input string too long for uint32"},
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{input: "C0", ptr: new(uint32), error: "rlp: expected input string or byte for uint32"},
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{input: "00", ptr: new(uint32), error: "rlp: non-canonical integer (leading zero bytes) for uint32"},
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{input: "820004", ptr: new(uint32), error: "rlp: non-canonical integer (leading zero bytes) for uint32"},
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{input: "B8020004", ptr: new(uint32), error: "rlp: non-canonical size information for uint32"},
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// slices
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{input: "C0", ptr: new([]uint), value: []uint{}},
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{input: "C80102030405060708", ptr: new([]uint), value: []uint{1, 2, 3, 4, 5, 6, 7, 8}},
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{input: "F8020004", ptr: new([]uint), error: "rlp: non-canonical size information for []uint"},
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// arrays
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{input: "C0", ptr: new([5]uint), value: [5]uint{}},
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{input: "C50102030405", ptr: new([5]uint), value: [5]uint{1, 2, 3, 4, 5}},
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{input: "C6010203040506", ptr: new([5]uint), error: "rlp: input list has too many elements for [5]uint"},
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{input: "F8020004", ptr: new([5]uint), error: "rlp: non-canonical size information for [5]uint"},
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// byte slices
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{input: "01", ptr: new([]byte), value: []byte{1}},
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@ -352,7 +369,7 @@ var decodeTests = []decodeTest{
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// big ints
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{input: "01", ptr: new(*big.Int), value: big.NewInt(1)},
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{input: "89FFFFFFFFFFFFFFFFFF", ptr: new(*big.Int), value: veryBigInt},
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{input: "820001", ptr: new(big.Int), error: "rlp: canon int error appends zero's for *big.Int"},
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{input: "820001", ptr: new(big.Int), error: "rlp: non-canonical integer (leading zero bytes) for *big.Int"},
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{input: "10", ptr: new(big.Int), value: *big.NewInt(16)}, // non-pointer also works
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{input: "C0", ptr: new(*big.Int), error: "rlp: expected input string or byte for *big.Int"},
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@ -366,6 +383,11 @@ var decodeTests = []decodeTest{
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value: recstruct{1, &recstruct{2, &recstruct{3, nil}}},
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},
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{
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input: "83222222",
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ptr: new(simplestruct),
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error: "rlp: expected input list for rlp.simplestruct",
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},
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{
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input: "C3010101",
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ptr: new(simplestruct),
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@ -378,7 +400,7 @@ var decodeTests = []decodeTest{
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},
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// pointers
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{input: "00", ptr: new(*uint), value: uintp(0)},
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{input: "00", ptr: new(*[]byte), value: &[]byte{0}},
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{input: "80", ptr: new(*uint), value: (*uint)(nil)},
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{input: "C0", ptr: new(*uint), value: (*uint)(nil)},
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{input: "07", ptr: new(*uint), value: uintp(7)},
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