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// Copyright 2015 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 "io"
// Split returns the content of first RLP value and any
// bytes after the value as subslices of b.
func Split(b []byte) (k Kind, content, rest []byte, err error) {
k, ts, cs, err := readKind(b)
if err != nil {
return 0, nil, b, err
}
return k, b[ts : ts+cs], b[ts+cs:], nil
}
// SplitString splits b into the content of an RLP string
// and any remaining bytes after the string.
func SplitString(b []byte) (content, rest []byte, err error) {
k, content, rest, err := Split(b)
if err != nil {
return nil, b, err
}
if k == List {
return nil, b, ErrExpectedString
}
return content, rest, nil
}
// SplitList splits b into the content of a list and any remaining
// bytes after the list.
func SplitList(b []byte) (content, rest []byte, err error) {
k, content, rest, err := Split(b)
if err != nil {
return nil, b, err
}
if k != List {
return nil, b, ErrExpectedList
}
return content, rest, nil
}
// CountValues counts the number of encoded values in b.
func CountValues(b []byte) (int, error) {
i := 0
for ; len(b) > 0; i++ {
_, tagsize, size, err := readKind(b)
if err != nil {
return 0, err
}
b = b[tagsize+size:]
}
return i, nil
}
func readKind(buf []byte) (k Kind, tagsize, contentsize uint64, err error) {
if len(buf) == 0 {
return 0, 0, 0, io.ErrUnexpectedEOF
}
b := buf[0]
switch {
case b < 0x80:
k = Byte
tagsize = 0
contentsize = 1
case b < 0xB8:
k = String
tagsize = 1
contentsize = uint64(b - 0x80)
// Reject strings that should've been single bytes.
if contentsize == 1 && buf[1] < 128 {
return 0, 0, 0, ErrCanonSize
}
case b < 0xC0:
k = String
tagsize = uint64(b-0xB7) + 1
contentsize, err = readSize(buf[1:], b-0xB7)
case b < 0xF8:
k = List
tagsize = 1
contentsize = uint64(b - 0xC0)
default:
k = List
tagsize = uint64(b-0xF7) + 1
contentsize, err = readSize(buf[1:], b-0xF7)
}
if err != nil {
return 0, 0, 0, err
}
// Reject values larger than the input slice.
if contentsize > uint64(len(buf))-tagsize {
return 0, 0, 0, ErrValueTooLarge
}
return k, tagsize, contentsize, err
}
func readSize(b []byte, slen byte) (uint64, error) {
if int(slen) > len(b) {
return 0, io.ErrUnexpectedEOF
}
var s uint64
switch slen {
case 1:
s = uint64(b[0])
case 2:
s = uint64(b[0])<<8 | uint64(b[1])
case 3:
s = uint64(b[0])<<16 | uint64(b[1])<<8 | uint64(b[2])
case 4:
s = uint64(b[0])<<24 | uint64(b[1])<<16 | uint64(b[2])<<8 | uint64(b[3])
case 5:
s = uint64(b[0])<<32 | uint64(b[1])<<24 | uint64(b[2])<<16 | uint64(b[3])<<8 | uint64(b[4])
case 6:
s = uint64(b[0])<<40 | uint64(b[1])<<32 | uint64(b[2])<<24 | uint64(b[3])<<16 | uint64(b[4])<<8 | uint64(b[5])
case 7:
s = uint64(b[0])<<48 | uint64(b[1])<<40 | uint64(b[2])<<32 | uint64(b[3])<<24 | uint64(b[4])<<16 | uint64(b[5])<<8 | uint64(b[6])
case 8:
s = uint64(b[0])<<56 | uint64(b[1])<<48 | uint64(b[2])<<40 | uint64(b[3])<<32 | uint64(b[4])<<24 | uint64(b[5])<<16 | uint64(b[6])<<8 | uint64(b[7])
}
// Reject sizes < 56 (shouldn't have separate size) and sizes with
// leading zero bytes.
if s < 56 || b[0] == 0 {
return 0, ErrCanonSize
}
return s, nil
}
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