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| 1 | +// Copyright 2015 The go-ethereum Authors |
| 2 | +// This file is part of the go-ethereum library. |
| 3 | +// |
| 4 | +// The go-ethereum library is free software: you can redistribute it and/or modify |
| 5 | +// it under the terms of the GNU Lesser General Public License as published by |
| 6 | +// the Free Software Foundation, either version 3 of the License, or |
| 7 | +// (at your option) any later version. |
| 8 | +// |
| 9 | +// The go-ethereum library is distributed in the hope that it will be useful, |
| 10 | +// but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 12 | +// GNU Lesser General Public License for more details. |
| 13 | +// |
| 14 | +// You should have received a copy of the GNU Lesser General Public License |
| 15 | +// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>. |
| 16 | + |
| 17 | +package rlp |
| 18 | + |
| 19 | +import ( |
| 20 | + "io" |
| 21 | + "reflect" |
| 22 | +) |
| 23 | + |
| 24 | +// RawValue represents an encoded RLP value and can be used to delay |
| 25 | +// RLP decoding or precompute an encoding. Note that the decoder does |
| 26 | +// not verify whether the content of RawValues is valid RLP. |
| 27 | +type RawValue []byte |
| 28 | + |
| 29 | +var rawValueType = reflect.TypeOf(RawValue{}) |
| 30 | + |
| 31 | +// ListSize returns the encoded size of an RLP list with the given |
| 32 | +// content size. |
| 33 | +func ListSize(contentSize uint64) uint64 { |
| 34 | + return uint64(headsize(contentSize)) + contentSize |
| 35 | +} |
| 36 | + |
| 37 | +// Split returns the content of first RLP value and any |
| 38 | +// bytes after the value as subslices of b. |
| 39 | +func Split(b []byte) (k Kind, content, rest []byte, err error) { |
| 40 | + k, ts, cs, err := readKind(b) |
| 41 | + if err != nil { |
| 42 | + return 0, nil, b, err |
| 43 | + } |
| 44 | + return k, b[ts : ts+cs], b[ts+cs:], nil |
| 45 | +} |
| 46 | + |
| 47 | +// SplitString splits b into the content of an RLP string |
| 48 | +// and any remaining bytes after the string. |
| 49 | +func SplitString(b []byte) (content, rest []byte, err error) { |
| 50 | + k, content, rest, err := Split(b) |
| 51 | + if err != nil { |
| 52 | + return nil, b, err |
| 53 | + } |
| 54 | + if k == List { |
| 55 | + return nil, b, ErrExpectedString |
| 56 | + } |
| 57 | + return content, rest, nil |
| 58 | +} |
| 59 | + |
| 60 | +// SplitList splits b into the content of a list and any remaining |
| 61 | +// bytes after the list. |
| 62 | +func SplitList(b []byte) (content, rest []byte, err error) { |
| 63 | + k, content, rest, err := Split(b) |
| 64 | + if err != nil { |
| 65 | + return nil, b, err |
| 66 | + } |
| 67 | + if k != List { |
| 68 | + return nil, b, ErrExpectedList |
| 69 | + } |
| 70 | + return content, rest, nil |
| 71 | +} |
| 72 | + |
| 73 | +// CountValues counts the number of encoded values in b. |
| 74 | +func CountValues(b []byte) (int, error) { |
| 75 | + i := 0 |
| 76 | + for ; len(b) > 0; i++ { |
| 77 | + _, tagsize, size, err := readKind(b) |
| 78 | + if err != nil { |
| 79 | + return 0, err |
| 80 | + } |
| 81 | + b = b[tagsize+size:] |
| 82 | + } |
| 83 | + return i, nil |
| 84 | +} |
| 85 | + |
| 86 | +func readKind(buf []byte) (k Kind, tagsize, contentsize uint64, err error) { |
| 87 | + if len(buf) == 0 { |
| 88 | + return 0, 0, 0, io.ErrUnexpectedEOF |
| 89 | + } |
| 90 | + b := buf[0] |
| 91 | + switch { |
| 92 | + case b < 0x80: |
| 93 | + k = Byte |
| 94 | + tagsize = 0 |
| 95 | + contentsize = 1 |
| 96 | + case b < 0xB8: |
| 97 | + k = String |
| 98 | + tagsize = 1 |
| 99 | + contentsize = uint64(b - 0x80) |
| 100 | + // Reject strings that should've been single bytes. |
| 101 | + if contentsize == 1 && buf[1] < 128 { |
| 102 | + return 0, 0, 0, ErrCanonSize |
| 103 | + } |
| 104 | + case b < 0xC0: |
| 105 | + k = String |
| 106 | + tagsize = uint64(b-0xB7) + 1 |
| 107 | + contentsize, err = readSize(buf[1:], b-0xB7) |
| 108 | + case b < 0xF8: |
| 109 | + k = List |
| 110 | + tagsize = 1 |
| 111 | + contentsize = uint64(b - 0xC0) |
| 112 | + default: |
| 113 | + k = List |
| 114 | + tagsize = uint64(b-0xF7) + 1 |
| 115 | + contentsize, err = readSize(buf[1:], b-0xF7) |
| 116 | + } |
| 117 | + if err != nil { |
| 118 | + return 0, 0, 0, err |
| 119 | + } |
| 120 | + // Reject values larger than the input slice. |
| 121 | + if contentsize > uint64(len(buf))-tagsize { |
| 122 | + return 0, 0, 0, ErrValueTooLarge |
| 123 | + } |
| 124 | + return k, tagsize, contentsize, err |
| 125 | +} |
| 126 | + |
| 127 | +func readSize(b []byte, slen byte) (uint64, error) { |
| 128 | + if int(slen) > len(b) { |
| 129 | + return 0, io.ErrUnexpectedEOF |
| 130 | + } |
| 131 | + var s uint64 |
| 132 | + switch slen { |
| 133 | + case 1: |
| 134 | + s = uint64(b[0]) |
| 135 | + case 2: |
| 136 | + s = uint64(b[0])<<8 | uint64(b[1]) |
| 137 | + case 3: |
| 138 | + s = uint64(b[0])<<16 | uint64(b[1])<<8 | uint64(b[2]) |
| 139 | + case 4: |
| 140 | + s = uint64(b[0])<<24 | uint64(b[1])<<16 | uint64(b[2])<<8 | uint64(b[3]) |
| 141 | + case 5: |
| 142 | + s = uint64(b[0])<<32 | uint64(b[1])<<24 | uint64(b[2])<<16 | uint64(b[3])<<8 | uint64(b[4]) |
| 143 | + case 6: |
| 144 | + s = uint64(b[0])<<40 | uint64(b[1])<<32 | uint64(b[2])<<24 | uint64(b[3])<<16 | uint64(b[4])<<8 | uint64(b[5]) |
| 145 | + case 7: |
| 146 | + 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]) |
| 147 | + case 8: |
| 148 | + 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]) |
| 149 | + } |
| 150 | + // Reject sizes < 56 (shouldn't have separate size) and sizes with |
| 151 | + // leading zero bytes. |
| 152 | + if s < 56 || b[0] == 0 { |
| 153 | + return 0, ErrCanonSize |
| 154 | + } |
| 155 | + return s, nil |
| 156 | +} |
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