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Diffstat (limited to 'vendor/github.com/ethereum/go-ethereum/rlp/decode.go')
| -rw-r--r-- | vendor/github.com/ethereum/go-ethereum/rlp/decode.go | 1049 |
1 files changed, 1049 insertions, 0 deletions
diff --git a/vendor/github.com/ethereum/go-ethereum/rlp/decode.go b/vendor/github.com/ethereum/go-ethereum/rlp/decode.go new file mode 100644 index 000000000..4f29f2fb0 --- /dev/null +++ b/vendor/github.com/ethereum/go-ethereum/rlp/decode.go @@ -0,0 +1,1049 @@ +// Copyright 2014 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 rlp + +import ( + "bufio" + "bytes" + "encoding/binary" + "errors" + "fmt" + "io" + "math/big" + "reflect" + "strings" + "sync" +) + +var ( + // EOL is returned when the end of the current list + // has been reached during streaming. + EOL = errors.New("rlp: end of list") + + // Actual Errors + ErrExpectedString = errors.New("rlp: expected String or Byte") + ErrExpectedList = errors.New("rlp: expected List") + ErrCanonInt = errors.New("rlp: non-canonical integer format") + ErrCanonSize = errors.New("rlp: non-canonical size information") + ErrElemTooLarge = errors.New("rlp: element is larger than containing list") + ErrValueTooLarge = errors.New("rlp: value size exceeds available input length") + ErrMoreThanOneValue = errors.New("rlp: input contains more than one value") + + // internal errors + errNotInList = errors.New("rlp: call of ListEnd outside of any list") + errNotAtEOL = errors.New("rlp: call of ListEnd not positioned at EOL") + errUintOverflow = errors.New("rlp: uint overflow") + errNoPointer = errors.New("rlp: interface given to Decode must be a pointer") + errDecodeIntoNil = errors.New("rlp: pointer given to Decode must not be nil") + + streamPool = sync.Pool{ + New: func() interface{} { return new(Stream) }, + } +) + +// 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. If r does +// not implement ByteReader, Decode will do its own buffering. +// +// 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 decode into the value pointed +// to. If the pointer is nil, a new value of the pointer's element +// type is allocated. If the pointer is non-nil, the existing value +// will be reused. +// +// 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. The input list +// must contain an element for each decoded field. Decode returns an +// error if there are too few or too many elements. +// +// The decoding of struct fields honours certain struct tags, "tail", +// "nil" and "-". +// +// The "-" tag ignores fields. +// +// For an explanation of "tail", see the example. +// +// The "nil" tag applies to pointer-typed fields and changes the decoding +// rules for the field such that input values of size zero decode as a nil +// pointer. This tag can be useful when decoding recursive types. +// +// type StructWithEmptyOK struct { +// Foo *[20]byte `rlp:"nil"` +// } +// +// To decode into a slice, the input must be a list and the resulting +// slice will contain the input elements in order. For byte slices, +// the input must be an RLP string. Array types decode similarly, with +// the additional restriction that the number of input elements (or +// bytes) must match the array's length. +// +// To decode into a Go string, the input must be an RLP string. The +// input bytes are taken as-is and will not necessarily be valid UTF-8. +// +// To decode into an unsigned 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 a boolean, the input must contain an unsigned integer +// of value zero (false) or one (true). +// +// 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 signed integers, +// floating point numbers, maps, channels and functions. +// +// Note that Decode does not set an input limit for all readers +// and may be vulnerable to panics cause by huge value sizes. If +// you need an input limit, use +// +// NewStream(r, limit).Decode(val) +func Decode(r io.Reader, val interface{}) error { + stream := streamPool.Get().(*Stream) + defer streamPool.Put(stream) + + stream.Reset(r, 0) + return stream.Decode(val) +} + +// DecodeBytes parses RLP data from b into val. +// Please see the documentation of Decode for the decoding rules. +// The input must contain exactly one value and no trailing data. +func DecodeBytes(b []byte, val interface{}) error { + r := bytes.NewReader(b) + + stream := streamPool.Get().(*Stream) + defer streamPool.Put(stream) + + stream.Reset(r, uint64(len(b))) + if err := stream.Decode(val); err != nil { + return err + } + if r.Len() > 0 { + return ErrMoreThanOneValue + } + return nil +} + +type decodeError struct { + msg string + typ reflect.Type + ctx []string +} + +func (err *decodeError) Error() string { + ctx := "" + if len(err.ctx) > 0 { + ctx = ", decoding into " + for i := len(err.ctx) - 1; i >= 0; i-- { + ctx += err.ctx[i] + } + } + return fmt.Sprintf("rlp: %s for %v%s", err.msg, err.typ, ctx) +} + +func wrapStreamError(err error, typ reflect.Type) error { + switch err { + case ErrCanonInt: + return &decodeError{msg: "non-canonical integer (leading zero bytes)", typ: typ} + case ErrCanonSize: + return &decodeError{msg: "non-canonical size information", typ: typ} + case ErrExpectedList: + return &decodeError{msg: "expected input list", typ: typ} + case ErrExpectedString: + return &decodeError{msg: "expected input string or byte", typ: typ} + case errUintOverflow: + return &decodeError{msg: "input string too long", typ: typ} + case errNotAtEOL: + return &decodeError{msg: "input list has too many elements", typ: typ} + } + return err +} + +func addErrorContext(err error, ctx string) error { + if decErr, ok := err.(*decodeError); ok { + decErr.ctx = append(decErr.ctx, ctx) + } + return err +} + +var ( + decoderInterface = reflect.TypeOf(new(Decoder)).Elem() + bigInt = reflect.TypeOf(big.Int{}) +) + +func makeDecoder(typ reflect.Type, tags tags) (dec decoder, err error) { + kind := typ.Kind() + switch { + case typ == rawValueType: + return decodeRawValue, nil + case typ.Implements(decoderInterface): + return decodeDecoder, nil + case kind != reflect.Ptr && reflect.PtrTo(typ).Implements(decoderInterface): + return decodeDecoderNoPtr, nil + case typ.AssignableTo(reflect.PtrTo(bigInt)): + return decodeBigInt, nil + case typ.AssignableTo(bigInt): + return decodeBigIntNoPtr, nil + case isUint(kind): + return decodeUint, nil + case kind == reflect.Bool: + return decodeBool, nil + case kind == reflect.String: + return decodeString, nil + case kind == reflect.Slice || kind == reflect.Array: + return makeListDecoder(typ, tags) + case kind == reflect.Struct: + return makeStructDecoder(typ) + case kind == reflect.Ptr: + if tags.nilOK { + return makeOptionalPtrDecoder(typ) + } + return makePtrDecoder(typ) + case kind == reflect.Interface: + return decodeInterface, nil + default: + return nil, fmt.Errorf("rlp: type %v is not RLP-serializable", typ) + } +} + +func decodeRawValue(s *Stream, val reflect.Value) error { + r, err := s.Raw() + if err != nil { + return err + } + val.SetBytes(r) + return nil +} + +func decodeUint(s *Stream, val reflect.Value) error { + typ := val.Type() + num, err := s.uint(typ.Bits()) + if err != nil { + return wrapStreamError(err, val.Type()) + } + val.SetUint(num) + return nil +} + +func decodeBool(s *Stream, val reflect.Value) error { + b, err := s.Bool() + if err != nil { + return wrapStreamError(err, val.Type()) + } + val.SetBool(b) + return nil +} + +func decodeString(s *Stream, val reflect.Value) error { + b, err := s.Bytes() + if err != nil { + return wrapStreamError(err, val.Type()) + } + 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 wrapStreamError(err, val.Type()) + } + i := val.Interface().(*big.Int) + if i == nil { + i = new(big.Int) + val.Set(reflect.ValueOf(i)) + } + // Reject leading zero bytes + if len(b) > 0 && b[0] == 0 { + return wrapStreamError(ErrCanonInt, val.Type()) + } + i.SetBytes(b) + return nil +} + +func makeListDecoder(typ reflect.Type, tag tags) (decoder, error) { + etype := typ.Elem() + if etype.Kind() == reflect.Uint8 && !reflect.PtrTo(etype).Implements(decoderInterface) { + if typ.Kind() == reflect.Array { + return decodeByteArray, nil + } + return decodeByteSlice, nil + } + etypeinfo := cachedTypeInfo1(etype, tags{}) + if etypeinfo.decoderErr != nil { + return nil, etypeinfo.decoderErr + } + var dec decoder + switch { + case typ.Kind() == reflect.Array: + dec = func(s *Stream, val reflect.Value) error { + return decodeListArray(s, val, etypeinfo.decoder) + } + case tag.tail: + // A slice with "tail" tag can occur as the last field + // of a struct and is supposed to swallow all remaining + // list elements. The struct decoder already called s.List, + // proceed directly to decoding the elements. + dec = func(s *Stream, val reflect.Value) error { + return decodeSliceElems(s, val, etypeinfo.decoder) + } + default: + dec = func(s *Stream, val reflect.Value) error { + return decodeListSlice(s, val, etypeinfo.decoder) + } + } + return dec, nil +} + +func decodeListSlice(s *Stream, val reflect.Value, elemdec decoder) error { + size, err := s.List() + if err != nil { + return wrapStreamError(err, val.Type()) + } + if size == 0 { + val.Set(reflect.MakeSlice(val.Type(), 0, 0)) + return s.ListEnd() + } + if err := decodeSliceElems(s, val, elemdec); err != nil { + return err + } + return s.ListEnd() +} + +func decodeSliceElems(s *Stream, val reflect.Value, elemdec decoder) error { + i := 0 + for ; ; i++ { + // 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 addErrorContext(err, fmt.Sprint("[", i, "]")) + } + } + if i < val.Len() { + val.SetLen(i) + } + return nil +} + +func decodeListArray(s *Stream, val reflect.Value, elemdec decoder) error { + if _, err := s.List(); err != nil { + return wrapStreamError(err, val.Type()) + } + vlen := val.Len() + i := 0 + for ; i < vlen; i++ { + if err := elemdec(s, val.Index(i)); err == EOL { + break + } else if err != nil { + return addErrorContext(err, fmt.Sprint("[", i, "]")) + } + } + if i < vlen { + return &decodeError{msg: "input list has too few elements", typ: val.Type()} + } + return wrapStreamError(s.ListEnd(), val.Type()) +} + +func decodeByteSlice(s *Stream, val reflect.Value) error { + b, err := s.Bytes() + if err != nil { + return wrapStreamError(err, val.Type()) + } + val.SetBytes(b) + return nil +} + +func decodeByteArray(s *Stream, val reflect.Value) error { + kind, size, err := s.Kind() + if err != nil { + return err + } + vlen := val.Len() + switch kind { + case Byte: + if vlen == 0 { + return &decodeError{msg: "input string too long", typ: val.Type()} + } + if vlen > 1 { + return &decodeError{msg: "input string too short", typ: val.Type()} + } + bv, _ := s.Uint() + val.Index(0).SetUint(bv) + case String: + if uint64(vlen) < size { + return &decodeError{msg: "input string too long", typ: val.Type()} + } + if uint64(vlen) > size { + return &decodeError{msg: "input string too short", typ: val.Type()} + } + slice := val.Slice(0, vlen).Interface().([]byte) + if err := s.readFull(slice); err != nil { + return err + } + // Reject cases where single byte encoding should have been used. + if size == 1 && slice[0] < 128 { + return wrapStreamError(ErrCanonSize, val.Type()) + } + case List: + return wrapStreamError(ErrExpectedString, val.Type()) + } + return nil +} + +func makeStructDecoder(typ reflect.Type) (decoder, error) { + fields, err := structFields(typ) + if err != nil { + return nil, err + } + dec := func(s *Stream, val reflect.Value) (err error) { + if _, err := s.List(); err != nil { + return wrapStreamError(err, typ) + } + for _, f := range fields { + err := f.info.decoder(s, val.Field(f.index)) + if err == EOL { + return &decodeError{msg: "too few elements", typ: typ} + } else if err != nil { + return addErrorContext(err, "."+typ.Field(f.index).Name) + } + } + return wrapStreamError(s.ListEnd(), typ) + } + return dec, nil +} + +// makePtrDecoder creates a decoder that decodes into +// the pointer's element type. +func makePtrDecoder(typ reflect.Type) (decoder, error) { + etype := typ.Elem() + etypeinfo := cachedTypeInfo1(etype, tags{}) + if etypeinfo.decoderErr != nil { + return nil, etypeinfo.decoderErr + } + dec := func(s *Stream, val reflect.Value) (err error) { + 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 +} + +// makeOptionalPtrDecoder creates a decoder that decodes empty values +// as nil. Non-empty values are decoded into a value of the element type, +// just like makePtrDecoder does. +// +// This decoder is used for pointer-typed struct fields with struct tag "nil". +func makeOptionalPtrDecoder(typ reflect.Type) (decoder, error) { + etype := typ.Elem() + etypeinfo := cachedTypeInfo1(etype, tags{}) + if etypeinfo.decoderErr != nil { + return nil, etypeinfo.decoderErr + } + dec := func(s *Stream, val reflect.Value) (err error) { + kind, size, err := s.Kind() + if err != nil || size == 0 && kind != Byte { + // rearm s.Kind. This is important because the input + // position must advance to the next value even though + // we don't read anything. + s.kind = -1 + // set the pointer to nil. + val.Set(reflect.Zero(typ)) + 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 { + if val.Type().NumMethod() != 0 { + return fmt.Errorf("rlp: type %v is not RLP-serializable", val.Type()) + } + kind, _, err := s.Kind() + if err != nil { + return err + } + if kind == List { + slice := reflect.New(ifsliceType).Elem() + if err := decodeListSlice(s, slice, decodeInterface); 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) + } +} + +// 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 + + // number of bytes remaining to be read from r. + remaining uint64 + limited bool + + // auxiliary buffer for integer decoding + uintbuf []byte + + kind Kind // kind of value ahead + size uint64 // size of value ahead + byteval byte // value of single byte in type tag + kinderr error // error from last readKind + stack []listpos +} + +type listpos struct{ pos, size uint64 } + +// NewStream creates a new decoding stream reading from r. +// +// If r implements the ByteReader interface, Stream will +// not introduce any buffering. +// +// For non-toplevel values, Stream returns ErrElemTooLarge +// for values that do not fit into the enclosing list. +// +// Stream supports an optional input limit. If a limit is set, the +// size of any toplevel value will be checked against the remaining +// input length. Stream operations that encounter a value exceeding +// the remaining input length will return ErrValueTooLarge. The limit +// can be set by passing a non-zero value for inputLimit. +// +// If r is a bytes.Reader or strings.Reader, the input limit is set to +// the length of r's underlying data unless an explicit limit is +// provided. +func NewStream(r io.Reader, inputLimit uint64) *Stream { + s := new(Stream) + s.Reset(r, inputLimit) + return s +} + +// NewListStream creates a new stream that pretends to be positioned +// at an encoded list of the given length. +func NewListStream(r io.Reader, len uint64) *Stream { + s := new(Stream) + s.Reset(r, len) + s.kind = List + s.size = len + return s +} + +// 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 + } + if size == 1 && b[0] < 128 { + return nil, ErrCanonSize + } + return b, nil + default: + return nil, ErrExpectedString + } +} + +// Raw reads a raw encoded value including RLP type information. +func (s *Stream) Raw() ([]byte, error) { + kind, size, err := s.Kind() + if err != nil { + return nil, err + } + if kind == Byte { + s.kind = -1 // rearm Kind + return []byte{s.byteval}, nil + } + // the original header has already been read and is no longer + // available. read content and put a new header in front of it. + start := headsize(size) + buf := make([]byte, uint64(start)+size) + if err := s.readFull(buf[start:]); err != nil { + return nil, err + } + if kind == String { + puthead(buf, 0x80, 0xB7, size) + } else { + puthead(buf, 0xC0, 0xF7, size) + } + return buf, nil +} + +// 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: + if s.byteval == 0 { + return 0, ErrCanonInt + } + s.kind = -1 // rearm Kind + return uint64(s.byteval), nil + case String: + if size > uint64(maxbits/8) { + return 0, errUintOverflow + } + v, err := s.readUint(byte(size)) + switch { + case err == ErrCanonSize: + // Adjust error because we're not reading a size right now. + return 0, ErrCanonInt + case err != nil: + return 0, err + case size > 0 && v < 128: + return 0, ErrCanonSize + default: + return v, nil + } + default: + return 0, ErrExpectedString + } +} + +// Bool reads an RLP string of up to 1 byte and returns its contents +// as a boolean. If the input does not contain an RLP string, the +// returned error will be ErrExpectedString. +func (s *Stream) Bool() (bool, error) { + num, err := s.uint(8) + if err != nil { + return false, err + } + switch num { + case 0: + return false, nil + case 1: + return true, nil + default: + return false, fmt.Errorf("rlp: invalid boolean value: %d", num) + } +} + +// 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 + } + decoder, err := cachedDecoder(rtyp.Elem()) + if err != nil { + return err + } + + err = decoder(s, rval.Elem()) + if decErr, ok := err.(*decodeError); ok && len(decErr.ctx) > 0 { + // add decode target type to error so context has more meaning + decErr.ctx = append(decErr.ctx, fmt.Sprint("(", rtyp.Elem(), ")")) + } + return err +} + +// Reset discards any information about the current decoding context +// and starts reading from r. This method is meant to facilitate reuse +// of a preallocated Stream across many decoding operations. +// +// If r does not also implement ByteReader, Stream will do its own +// buffering. +func (s *Stream) Reset(r io.Reader, inputLimit uint64) { + if inputLimit > 0 { + s.remaining = inputLimit + s.limited = true + } else { + // Attempt to automatically discover + // the limit when reading from a byte slice. + switch br := r.(type) { + case *bytes.Reader: + s.remaining = uint64(br.Len()) + s.limited = true + case *strings.Reader: + s.remaining = uint64(br.Len()) + s.limited = true + default: + s.limited = false + } + } + // Wrap r with a buffer if it doesn't have one. + bufr, ok := r.(ByteReader) + if !ok { + bufr = bufio.NewReader(r) + } + s.r = bufr + // Reset the decoding context. + s.stack = s.stack[:0] + s.size = 0 + s.kind = -1 + s.kinderr = nil + if s.uintbuf == nil { + s.uintbuf = make([]byte, 8) + } + s.byteval = 0 +} + +// 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 { + s.kinderr = nil + // Don't read further if we're at the end of the + // innermost list. + if tos != nil && tos.pos == tos.size { + return 0, 0, EOL + } + s.kind, s.size, s.kinderr = s.readKind() + if s.kinderr == nil { + if tos == nil { + // At toplevel, check that the value is smaller + // than the remaining input length. + if s.limited && s.size > s.remaining { + s.kinderr = ErrValueTooLarge + } + } else { + // Inside a list, check that the value doesn't overflow the list. + if s.size > tos.size-tos.pos { + s.kinderr = ErrElemTooLarge + } + } + } + } + // Note: this might return a sticky error generated + // by an earlier call to readKind. + return s.kind, s.size, s.kinderr +} + +func (s *Stream) readKind() (kind Kind, size uint64, err error) { + b, err := s.readByte() + if err != nil { + if len(s.stack) == 0 { + // At toplevel, Adjust the error to actual EOF. io.EOF is + // used by callers to determine when to stop decoding. + switch err { + case io.ErrUnexpectedEOF: + err = io.EOF + case ErrValueTooLarge: + err = io.EOF + } + } + 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) + if err == nil && size < 56 { + err = ErrCanonSize + } + 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) + if err == nil && size < 56 { + err = ErrCanonSize + } + return List, size, err + } +} + +func (s *Stream) readUint(size byte) (uint64, error) { + switch size { + case 0: + s.kind = -1 // rearm Kind + return 0, nil + case 1: + b, err := s.readByte() + return uint64(b), err + default: + start := int(8 - size) + for i := 0; i < start; i++ { + s.uintbuf[i] = 0 + } + if err := s.readFull(s.uintbuf[start:]); err != nil { + return 0, err + } + if s.uintbuf[start] == 0 { + // Note: readUint is also used to decode integer + // values. The error needs to be adjusted to become + // ErrCanonInt in this case. + return 0, ErrCanonSize + } + return binary.BigEndian.Uint64(s.uintbuf), nil + } +} + +func (s *Stream) readFull(buf []byte) (err error) { + if err := s.willRead(uint64(len(buf))); err != nil { + return err + } + 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) { + if err := s.willRead(1); err != nil { + return 0, err + } + b, err := s.r.ReadByte() + if err == io.EOF { + err = io.ErrUnexpectedEOF + } + return b, err +} + +func (s *Stream) willRead(n uint64) error { + s.kind = -1 // rearm Kind + + if len(s.stack) > 0 { + // check list overflow + tos := s.stack[len(s.stack)-1] + if n > tos.size-tos.pos { + return ErrElemTooLarge + } + s.stack[len(s.stack)-1].pos += n + } + if s.limited { + if n > s.remaining { + return ErrValueTooLarge + } + s.remaining -= n + } + return nil +} |