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opcode.go
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opcode.go
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// Copyright (c) 2013-2017 The btcsuite developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
package txscript
import (
"bytes"
"crypto/sha1"
"crypto/sha256"
"encoding/hex"
"fmt"
"hash"
"strings"
"golang.org/x/crypto/ripemd160"
"github.com/btcsuite/btcd/btcec/v2"
"github.com/btcsuite/btcd/chaincfg/chainhash"
"github.com/btcsuite/btcd/wire"
)
// An opcode defines the information related to a txscript opcode. opfunc, if
// present, is the function to call to perform the opcode on the script. The
// current script is passed in as a slice with the first member being the opcode
// itself.
type opcode struct {
value byte
name string
length int
opfunc func(*opcode, []byte, *Engine) error
}
// These constants are the values of the official opcodes used on the btc wiki,
// in bitcoin core and in most if not all other references and software related
// to handling BTC scripts.
const (
OP_0 = 0x00 // 0
OP_FALSE = 0x00 // 0 - AKA OP_0
OP_DATA_1 = 0x01 // 1
OP_DATA_2 = 0x02 // 2
OP_DATA_3 = 0x03 // 3
OP_DATA_4 = 0x04 // 4
OP_DATA_5 = 0x05 // 5
OP_DATA_6 = 0x06 // 6
OP_DATA_7 = 0x07 // 7
OP_DATA_8 = 0x08 // 8
OP_DATA_9 = 0x09 // 9
OP_DATA_10 = 0x0a // 10
OP_DATA_11 = 0x0b // 11
OP_DATA_12 = 0x0c // 12
OP_DATA_13 = 0x0d // 13
OP_DATA_14 = 0x0e // 14
OP_DATA_15 = 0x0f // 15
OP_DATA_16 = 0x10 // 16
OP_DATA_17 = 0x11 // 17
OP_DATA_18 = 0x12 // 18
OP_DATA_19 = 0x13 // 19
OP_DATA_20 = 0x14 // 20
OP_DATA_21 = 0x15 // 21
OP_DATA_22 = 0x16 // 22
OP_DATA_23 = 0x17 // 23
OP_DATA_24 = 0x18 // 24
OP_DATA_25 = 0x19 // 25
OP_DATA_26 = 0x1a // 26
OP_DATA_27 = 0x1b // 27
OP_DATA_28 = 0x1c // 28
OP_DATA_29 = 0x1d // 29
OP_DATA_30 = 0x1e // 30
OP_DATA_31 = 0x1f // 31
OP_DATA_32 = 0x20 // 32
OP_DATA_33 = 0x21 // 33
OP_DATA_34 = 0x22 // 34
OP_DATA_35 = 0x23 // 35
OP_DATA_36 = 0x24 // 36
OP_DATA_37 = 0x25 // 37
OP_DATA_38 = 0x26 // 38
OP_DATA_39 = 0x27 // 39
OP_DATA_40 = 0x28 // 40
OP_DATA_41 = 0x29 // 41
OP_DATA_42 = 0x2a // 42
OP_DATA_43 = 0x2b // 43
OP_DATA_44 = 0x2c // 44
OP_DATA_45 = 0x2d // 45
OP_DATA_46 = 0x2e // 46
OP_DATA_47 = 0x2f // 47
OP_DATA_48 = 0x30 // 48
OP_DATA_49 = 0x31 // 49
OP_DATA_50 = 0x32 // 50
OP_DATA_51 = 0x33 // 51
OP_DATA_52 = 0x34 // 52
OP_DATA_53 = 0x35 // 53
OP_DATA_54 = 0x36 // 54
OP_DATA_55 = 0x37 // 55
OP_DATA_56 = 0x38 // 56
OP_DATA_57 = 0x39 // 57
OP_DATA_58 = 0x3a // 58
OP_DATA_59 = 0x3b // 59
OP_DATA_60 = 0x3c // 60
OP_DATA_61 = 0x3d // 61
OP_DATA_62 = 0x3e // 62
OP_DATA_63 = 0x3f // 63
OP_DATA_64 = 0x40 // 64
OP_DATA_65 = 0x41 // 65
OP_DATA_66 = 0x42 // 66
OP_DATA_67 = 0x43 // 67
OP_DATA_68 = 0x44 // 68
OP_DATA_69 = 0x45 // 69
OP_DATA_70 = 0x46 // 70
OP_DATA_71 = 0x47 // 71
OP_DATA_72 = 0x48 // 72
OP_DATA_73 = 0x49 // 73
OP_DATA_74 = 0x4a // 74
OP_DATA_75 = 0x4b // 75
OP_PUSHDATA1 = 0x4c // 76
OP_PUSHDATA2 = 0x4d // 77
OP_PUSHDATA4 = 0x4e // 78
OP_1NEGATE = 0x4f // 79
OP_RESERVED = 0x50 // 80
OP_1 = 0x51 // 81 - AKA OP_TRUE
OP_TRUE = 0x51 // 81
OP_2 = 0x52 // 82
OP_3 = 0x53 // 83
OP_4 = 0x54 // 84
OP_5 = 0x55 // 85
OP_6 = 0x56 // 86
OP_7 = 0x57 // 87
OP_8 = 0x58 // 88
OP_9 = 0x59 // 89
OP_10 = 0x5a // 90
OP_11 = 0x5b // 91
OP_12 = 0x5c // 92
OP_13 = 0x5d // 93
OP_14 = 0x5e // 94
OP_15 = 0x5f // 95
OP_16 = 0x60 // 96
OP_NOP = 0x61 // 97
OP_VER = 0x62 // 98
OP_IF = 0x63 // 99
OP_NOTIF = 0x64 // 100
OP_VERIF = 0x65 // 101
OP_VERNOTIF = 0x66 // 102
OP_ELSE = 0x67 // 103
OP_ENDIF = 0x68 // 104
OP_VERIFY = 0x69 // 105
OP_RETURN = 0x6a // 106
OP_TOALTSTACK = 0x6b // 107
OP_FROMALTSTACK = 0x6c // 108
OP_2DROP = 0x6d // 109
OP_2DUP = 0x6e // 110
OP_3DUP = 0x6f // 111
OP_2OVER = 0x70 // 112
OP_2ROT = 0x71 // 113
OP_2SWAP = 0x72 // 114
OP_IFDUP = 0x73 // 115
OP_DEPTH = 0x74 // 116
OP_DROP = 0x75 // 117
OP_DUP = 0x76 // 118
OP_NIP = 0x77 // 119
OP_OVER = 0x78 // 120
OP_PICK = 0x79 // 121
OP_ROLL = 0x7a // 122
OP_ROT = 0x7b // 123
OP_SWAP = 0x7c // 124
OP_TUCK = 0x7d // 125
OP_CAT = 0x7e // 126
OP_SUBSTR = 0x7f // 127
OP_LEFT = 0x80 // 128
OP_RIGHT = 0x81 // 129
OP_SIZE = 0x82 // 130
OP_INVERT = 0x83 // 131
OP_AND = 0x84 // 132
OP_OR = 0x85 // 133
OP_XOR = 0x86 // 134
OP_EQUAL = 0x87 // 135
OP_EQUALVERIFY = 0x88 // 136
OP_RESERVED1 = 0x89 // 137
OP_RESERVED2 = 0x8a // 138
OP_1ADD = 0x8b // 139
OP_1SUB = 0x8c // 140
OP_2MUL = 0x8d // 141
OP_2DIV = 0x8e // 142
OP_NEGATE = 0x8f // 143
OP_ABS = 0x90 // 144
OP_NOT = 0x91 // 145
OP_0NOTEQUAL = 0x92 // 146
OP_ADD = 0x93 // 147
OP_SUB = 0x94 // 148
OP_MUL = 0x95 // 149
OP_DIV = 0x96 // 150
OP_MOD = 0x97 // 151
OP_LSHIFT = 0x98 // 152
OP_RSHIFT = 0x99 // 153
OP_BOOLAND = 0x9a // 154
OP_BOOLOR = 0x9b // 155
OP_NUMEQUAL = 0x9c // 156
OP_NUMEQUALVERIFY = 0x9d // 157
OP_NUMNOTEQUAL = 0x9e // 158
OP_LESSTHAN = 0x9f // 159
OP_GREATERTHAN = 0xa0 // 160
OP_LESSTHANOREQUAL = 0xa1 // 161
OP_GREATERTHANOREQUAL = 0xa2 // 162
OP_MIN = 0xa3 // 163
OP_MAX = 0xa4 // 164
OP_WITHIN = 0xa5 // 165
OP_RIPEMD160 = 0xa6 // 166
OP_SHA1 = 0xa7 // 167
OP_SHA256 = 0xa8 // 168
OP_HASH160 = 0xa9 // 169
OP_HASH256 = 0xaa // 170
OP_CODESEPARATOR = 0xab // 171
OP_CHECKSIG = 0xac // 172
OP_CHECKSIGVERIFY = 0xad // 173
OP_CHECKMULTISIG = 0xae // 174
OP_CHECKMULTISIGVERIFY = 0xaf // 175
OP_NOP1 = 0xb0 // 176
OP_NOP2 = 0xb1 // 177
OP_CHECKLOCKTIMEVERIFY = 0xb1 // 177 - AKA OP_NOP2
OP_NOP3 = 0xb2 // 178
OP_CHECKSEQUENCEVERIFY = 0xb2 // 178 - AKA OP_NOP3
OP_NOP4 = 0xb3 // 179
OP_NOP5 = 0xb4 // 180
OP_NOP6 = 0xb5 // 181
OP_NOP7 = 0xb6 // 182
OP_NOP8 = 0xb7 // 183
OP_NOP9 = 0xb8 // 184
OP_NOP10 = 0xb9 // 185
OP_UNKNOWN186 = 0xba // 186
OP_UNKNOWN187 = 0xbb // 187
OP_UNKNOWN188 = 0xbc // 188
OP_UNKNOWN189 = 0xbd // 189
OP_UNKNOWN190 = 0xbe // 190
OP_UNKNOWN191 = 0xbf // 191
OP_UNKNOWN192 = 0xc0 // 192
OP_UNKNOWN193 = 0xc1 // 193
OP_UNKNOWN194 = 0xc2 // 194
OP_UNKNOWN195 = 0xc3 // 195
OP_UNKNOWN196 = 0xc4 // 196
OP_UNKNOWN197 = 0xc5 // 197
OP_UNKNOWN198 = 0xc6 // 198
OP_UNKNOWN199 = 0xc7 // 199
OP_UNKNOWN200 = 0xc8 // 200
OP_UNKNOWN201 = 0xc9 // 201
OP_UNKNOWN202 = 0xca // 202
OP_UNKNOWN203 = 0xcb // 203
OP_UNKNOWN204 = 0xcc // 204
OP_UNKNOWN205 = 0xcd // 205
OP_UNKNOWN206 = 0xce // 206
OP_UNKNOWN207 = 0xcf // 207
OP_UNKNOWN208 = 0xd0 // 208
OP_UNKNOWN209 = 0xd1 // 209
OP_UNKNOWN210 = 0xd2 // 210
OP_UNKNOWN211 = 0xd3 // 211
OP_UNKNOWN212 = 0xd4 // 212
OP_UNKNOWN213 = 0xd5 // 213
OP_UNKNOWN214 = 0xd6 // 214
OP_UNKNOWN215 = 0xd7 // 215
OP_UNKNOWN216 = 0xd8 // 216
OP_UNKNOWN217 = 0xd9 // 217
OP_UNKNOWN218 = 0xda // 218
OP_UNKNOWN219 = 0xdb // 219
OP_UNKNOWN220 = 0xdc // 220
OP_UNKNOWN221 = 0xdd // 221
OP_UNKNOWN222 = 0xde // 222
OP_UNKNOWN223 = 0xdf // 223
OP_UNKNOWN224 = 0xe0 // 224
OP_UNKNOWN225 = 0xe1 // 225
OP_UNKNOWN226 = 0xe2 // 226
OP_UNKNOWN227 = 0xe3 // 227
OP_UNKNOWN228 = 0xe4 // 228
OP_UNKNOWN229 = 0xe5 // 229
OP_UNKNOWN230 = 0xe6 // 230
OP_UNKNOWN231 = 0xe7 // 231
OP_UNKNOWN232 = 0xe8 // 232
OP_UNKNOWN233 = 0xe9 // 233
OP_UNKNOWN234 = 0xea // 234
OP_UNKNOWN235 = 0xeb // 235
OP_UNKNOWN236 = 0xec // 236
OP_UNKNOWN237 = 0xed // 237
OP_UNKNOWN238 = 0xee // 238
OP_UNKNOWN239 = 0xef // 239
OP_UNKNOWN240 = 0xf0 // 240
OP_UNKNOWN241 = 0xf1 // 241
OP_UNKNOWN242 = 0xf2 // 242
OP_UNKNOWN243 = 0xf3 // 243
OP_UNKNOWN244 = 0xf4 // 244
OP_UNKNOWN245 = 0xf5 // 245
OP_UNKNOWN246 = 0xf6 // 246
OP_UNKNOWN247 = 0xf7 // 247
OP_UNKNOWN248 = 0xf8 // 248
OP_UNKNOWN249 = 0xf9 // 249
OP_SMALLINTEGER = 0xfa // 250 - bitcoin core internal
OP_PUBKEYS = 0xfb // 251 - bitcoin core internal
OP_UNKNOWN252 = 0xfc // 252
OP_PUBKEYHASH = 0xfd // 253 - bitcoin core internal
OP_PUBKEY = 0xfe // 254 - bitcoin core internal
OP_INVALIDOPCODE = 0xff // 255 - bitcoin core internal
)
// Conditional execution constants.
const (
OpCondFalse = 0
OpCondTrue = 1
OpCondSkip = 2
)
// opcodeArray holds details about all possible opcodes such as how many bytes
// the opcode and any associated data should take, its human-readable name, and
// the handler function.
var opcodeArray = [256]opcode{
// Data push opcodes.
OP_FALSE: {OP_FALSE, "OP_0", 1, opcodeFalse},
OP_DATA_1: {OP_DATA_1, "OP_DATA_1", 2, opcodePushData},
OP_DATA_2: {OP_DATA_2, "OP_DATA_2", 3, opcodePushData},
OP_DATA_3: {OP_DATA_3, "OP_DATA_3", 4, opcodePushData},
OP_DATA_4: {OP_DATA_4, "OP_DATA_4", 5, opcodePushData},
OP_DATA_5: {OP_DATA_5, "OP_DATA_5", 6, opcodePushData},
OP_DATA_6: {OP_DATA_6, "OP_DATA_6", 7, opcodePushData},
OP_DATA_7: {OP_DATA_7, "OP_DATA_7", 8, opcodePushData},
OP_DATA_8: {OP_DATA_8, "OP_DATA_8", 9, opcodePushData},
OP_DATA_9: {OP_DATA_9, "OP_DATA_9", 10, opcodePushData},
OP_DATA_10: {OP_DATA_10, "OP_DATA_10", 11, opcodePushData},
OP_DATA_11: {OP_DATA_11, "OP_DATA_11", 12, opcodePushData},
OP_DATA_12: {OP_DATA_12, "OP_DATA_12", 13, opcodePushData},
OP_DATA_13: {OP_DATA_13, "OP_DATA_13", 14, opcodePushData},
OP_DATA_14: {OP_DATA_14, "OP_DATA_14", 15, opcodePushData},
OP_DATA_15: {OP_DATA_15, "OP_DATA_15", 16, opcodePushData},
OP_DATA_16: {OP_DATA_16, "OP_DATA_16", 17, opcodePushData},
OP_DATA_17: {OP_DATA_17, "OP_DATA_17", 18, opcodePushData},
OP_DATA_18: {OP_DATA_18, "OP_DATA_18", 19, opcodePushData},
OP_DATA_19: {OP_DATA_19, "OP_DATA_19", 20, opcodePushData},
OP_DATA_20: {OP_DATA_20, "OP_DATA_20", 21, opcodePushData},
OP_DATA_21: {OP_DATA_21, "OP_DATA_21", 22, opcodePushData},
OP_DATA_22: {OP_DATA_22, "OP_DATA_22", 23, opcodePushData},
OP_DATA_23: {OP_DATA_23, "OP_DATA_23", 24, opcodePushData},
OP_DATA_24: {OP_DATA_24, "OP_DATA_24", 25, opcodePushData},
OP_DATA_25: {OP_DATA_25, "OP_DATA_25", 26, opcodePushData},
OP_DATA_26: {OP_DATA_26, "OP_DATA_26", 27, opcodePushData},
OP_DATA_27: {OP_DATA_27, "OP_DATA_27", 28, opcodePushData},
OP_DATA_28: {OP_DATA_28, "OP_DATA_28", 29, opcodePushData},
OP_DATA_29: {OP_DATA_29, "OP_DATA_29", 30, opcodePushData},
OP_DATA_30: {OP_DATA_30, "OP_DATA_30", 31, opcodePushData},
OP_DATA_31: {OP_DATA_31, "OP_DATA_31", 32, opcodePushData},
OP_DATA_32: {OP_DATA_32, "OP_DATA_32", 33, opcodePushData},
OP_DATA_33: {OP_DATA_33, "OP_DATA_33", 34, opcodePushData},
OP_DATA_34: {OP_DATA_34, "OP_DATA_34", 35, opcodePushData},
OP_DATA_35: {OP_DATA_35, "OP_DATA_35", 36, opcodePushData},
OP_DATA_36: {OP_DATA_36, "OP_DATA_36", 37, opcodePushData},
OP_DATA_37: {OP_DATA_37, "OP_DATA_37", 38, opcodePushData},
OP_DATA_38: {OP_DATA_38, "OP_DATA_38", 39, opcodePushData},
OP_DATA_39: {OP_DATA_39, "OP_DATA_39", 40, opcodePushData},
OP_DATA_40: {OP_DATA_40, "OP_DATA_40", 41, opcodePushData},
OP_DATA_41: {OP_DATA_41, "OP_DATA_41", 42, opcodePushData},
OP_DATA_42: {OP_DATA_42, "OP_DATA_42", 43, opcodePushData},
OP_DATA_43: {OP_DATA_43, "OP_DATA_43", 44, opcodePushData},
OP_DATA_44: {OP_DATA_44, "OP_DATA_44", 45, opcodePushData},
OP_DATA_45: {OP_DATA_45, "OP_DATA_45", 46, opcodePushData},
OP_DATA_46: {OP_DATA_46, "OP_DATA_46", 47, opcodePushData},
OP_DATA_47: {OP_DATA_47, "OP_DATA_47", 48, opcodePushData},
OP_DATA_48: {OP_DATA_48, "OP_DATA_48", 49, opcodePushData},
OP_DATA_49: {OP_DATA_49, "OP_DATA_49", 50, opcodePushData},
OP_DATA_50: {OP_DATA_50, "OP_DATA_50", 51, opcodePushData},
OP_DATA_51: {OP_DATA_51, "OP_DATA_51", 52, opcodePushData},
OP_DATA_52: {OP_DATA_52, "OP_DATA_52", 53, opcodePushData},
OP_DATA_53: {OP_DATA_53, "OP_DATA_53", 54, opcodePushData},
OP_DATA_54: {OP_DATA_54, "OP_DATA_54", 55, opcodePushData},
OP_DATA_55: {OP_DATA_55, "OP_DATA_55", 56, opcodePushData},
OP_DATA_56: {OP_DATA_56, "OP_DATA_56", 57, opcodePushData},
OP_DATA_57: {OP_DATA_57, "OP_DATA_57", 58, opcodePushData},
OP_DATA_58: {OP_DATA_58, "OP_DATA_58", 59, opcodePushData},
OP_DATA_59: {OP_DATA_59, "OP_DATA_59", 60, opcodePushData},
OP_DATA_60: {OP_DATA_60, "OP_DATA_60", 61, opcodePushData},
OP_DATA_61: {OP_DATA_61, "OP_DATA_61", 62, opcodePushData},
OP_DATA_62: {OP_DATA_62, "OP_DATA_62", 63, opcodePushData},
OP_DATA_63: {OP_DATA_63, "OP_DATA_63", 64, opcodePushData},
OP_DATA_64: {OP_DATA_64, "OP_DATA_64", 65, opcodePushData},
OP_DATA_65: {OP_DATA_65, "OP_DATA_65", 66, opcodePushData},
OP_DATA_66: {OP_DATA_66, "OP_DATA_66", 67, opcodePushData},
OP_DATA_67: {OP_DATA_67, "OP_DATA_67", 68, opcodePushData},
OP_DATA_68: {OP_DATA_68, "OP_DATA_68", 69, opcodePushData},
OP_DATA_69: {OP_DATA_69, "OP_DATA_69", 70, opcodePushData},
OP_DATA_70: {OP_DATA_70, "OP_DATA_70", 71, opcodePushData},
OP_DATA_71: {OP_DATA_71, "OP_DATA_71", 72, opcodePushData},
OP_DATA_72: {OP_DATA_72, "OP_DATA_72", 73, opcodePushData},
OP_DATA_73: {OP_DATA_73, "OP_DATA_73", 74, opcodePushData},
OP_DATA_74: {OP_DATA_74, "OP_DATA_74", 75, opcodePushData},
OP_DATA_75: {OP_DATA_75, "OP_DATA_75", 76, opcodePushData},
OP_PUSHDATA1: {OP_PUSHDATA1, "OP_PUSHDATA1", -1, opcodePushData},
OP_PUSHDATA2: {OP_PUSHDATA2, "OP_PUSHDATA2", -2, opcodePushData},
OP_PUSHDATA4: {OP_PUSHDATA4, "OP_PUSHDATA4", -4, opcodePushData},
OP_1NEGATE: {OP_1NEGATE, "OP_1NEGATE", 1, opcode1Negate},
OP_RESERVED: {OP_RESERVED, "OP_RESERVED", 1, opcodeReserved},
OP_TRUE: {OP_TRUE, "OP_1", 1, opcodeN},
OP_2: {OP_2, "OP_2", 1, opcodeN},
OP_3: {OP_3, "OP_3", 1, opcodeN},
OP_4: {OP_4, "OP_4", 1, opcodeN},
OP_5: {OP_5, "OP_5", 1, opcodeN},
OP_6: {OP_6, "OP_6", 1, opcodeN},
OP_7: {OP_7, "OP_7", 1, opcodeN},
OP_8: {OP_8, "OP_8", 1, opcodeN},
OP_9: {OP_9, "OP_9", 1, opcodeN},
OP_10: {OP_10, "OP_10", 1, opcodeN},
OP_11: {OP_11, "OP_11", 1, opcodeN},
OP_12: {OP_12, "OP_12", 1, opcodeN},
OP_13: {OP_13, "OP_13", 1, opcodeN},
OP_14: {OP_14, "OP_14", 1, opcodeN},
OP_15: {OP_15, "OP_15", 1, opcodeN},
OP_16: {OP_16, "OP_16", 1, opcodeN},
// Control opcodes.
OP_NOP: {OP_NOP, "OP_NOP", 1, opcodeNop},
OP_VER: {OP_VER, "OP_VER", 1, opcodeReserved},
OP_IF: {OP_IF, "OP_IF", 1, opcodeIf},
OP_NOTIF: {OP_NOTIF, "OP_NOTIF", 1, opcodeNotIf},
OP_VERIF: {OP_VERIF, "OP_VERIF", 1, opcodeReserved},
OP_VERNOTIF: {OP_VERNOTIF, "OP_VERNOTIF", 1, opcodeReserved},
OP_ELSE: {OP_ELSE, "OP_ELSE", 1, opcodeElse},
OP_ENDIF: {OP_ENDIF, "OP_ENDIF", 1, opcodeEndif},
OP_VERIFY: {OP_VERIFY, "OP_VERIFY", 1, opcodeVerify},
OP_RETURN: {OP_RETURN, "OP_RETURN", 1, opcodeReturn},
OP_CHECKLOCKTIMEVERIFY: {OP_CHECKLOCKTIMEVERIFY, "OP_CHECKLOCKTIMEVERIFY", 1, opcodeCheckLockTimeVerify},
OP_CHECKSEQUENCEVERIFY: {OP_CHECKSEQUENCEVERIFY, "OP_CHECKSEQUENCEVERIFY", 1, opcodeCheckSequenceVerify},
// Stack opcodes.
OP_TOALTSTACK: {OP_TOALTSTACK, "OP_TOALTSTACK", 1, opcodeToAltStack},
OP_FROMALTSTACK: {OP_FROMALTSTACK, "OP_FROMALTSTACK", 1, opcodeFromAltStack},
OP_2DROP: {OP_2DROP, "OP_2DROP", 1, opcode2Drop},
OP_2DUP: {OP_2DUP, "OP_2DUP", 1, opcode2Dup},
OP_3DUP: {OP_3DUP, "OP_3DUP", 1, opcode3Dup},
OP_2OVER: {OP_2OVER, "OP_2OVER", 1, opcode2Over},
OP_2ROT: {OP_2ROT, "OP_2ROT", 1, opcode2Rot},
OP_2SWAP: {OP_2SWAP, "OP_2SWAP", 1, opcode2Swap},
OP_IFDUP: {OP_IFDUP, "OP_IFDUP", 1, opcodeIfDup},
OP_DEPTH: {OP_DEPTH, "OP_DEPTH", 1, opcodeDepth},
OP_DROP: {OP_DROP, "OP_DROP", 1, opcodeDrop},
OP_DUP: {OP_DUP, "OP_DUP", 1, opcodeDup},
OP_NIP: {OP_NIP, "OP_NIP", 1, opcodeNip},
OP_OVER: {OP_OVER, "OP_OVER", 1, opcodeOver},
OP_PICK: {OP_PICK, "OP_PICK", 1, opcodePick},
OP_ROLL: {OP_ROLL, "OP_ROLL", 1, opcodeRoll},
OP_ROT: {OP_ROT, "OP_ROT", 1, opcodeRot},
OP_SWAP: {OP_SWAP, "OP_SWAP", 1, opcodeSwap},
OP_TUCK: {OP_TUCK, "OP_TUCK", 1, opcodeTuck},
// Splice opcodes.
OP_CAT: {OP_CAT, "OP_CAT", 1, opcodeDisabled},
OP_SUBSTR: {OP_SUBSTR, "OP_SUBSTR", 1, opcodeDisabled},
OP_LEFT: {OP_LEFT, "OP_LEFT", 1, opcodeDisabled},
OP_RIGHT: {OP_RIGHT, "OP_RIGHT", 1, opcodeDisabled},
OP_SIZE: {OP_SIZE, "OP_SIZE", 1, opcodeSize},
// Bitwise logic opcodes.
OP_INVERT: {OP_INVERT, "OP_INVERT", 1, opcodeDisabled},
OP_AND: {OP_AND, "OP_AND", 1, opcodeDisabled},
OP_OR: {OP_OR, "OP_OR", 1, opcodeDisabled},
OP_XOR: {OP_XOR, "OP_XOR", 1, opcodeDisabled},
OP_EQUAL: {OP_EQUAL, "OP_EQUAL", 1, opcodeEqual},
OP_EQUALVERIFY: {OP_EQUALVERIFY, "OP_EQUALVERIFY", 1, opcodeEqualVerify},
OP_RESERVED1: {OP_RESERVED1, "OP_RESERVED1", 1, opcodeReserved},
OP_RESERVED2: {OP_RESERVED2, "OP_RESERVED2", 1, opcodeReserved},
// Numeric related opcodes.
OP_1ADD: {OP_1ADD, "OP_1ADD", 1, opcode1Add},
OP_1SUB: {OP_1SUB, "OP_1SUB", 1, opcode1Sub},
OP_2MUL: {OP_2MUL, "OP_2MUL", 1, opcodeDisabled},
OP_2DIV: {OP_2DIV, "OP_2DIV", 1, opcodeDisabled},
OP_NEGATE: {OP_NEGATE, "OP_NEGATE", 1, opcodeNegate},
OP_ABS: {OP_ABS, "OP_ABS", 1, opcodeAbs},
OP_NOT: {OP_NOT, "OP_NOT", 1, opcodeNot},
OP_0NOTEQUAL: {OP_0NOTEQUAL, "OP_0NOTEQUAL", 1, opcode0NotEqual},
OP_ADD: {OP_ADD, "OP_ADD", 1, opcodeAdd},
OP_SUB: {OP_SUB, "OP_SUB", 1, opcodeSub},
OP_MUL: {OP_MUL, "OP_MUL", 1, opcodeDisabled},
OP_DIV: {OP_DIV, "OP_DIV", 1, opcodeDisabled},
OP_MOD: {OP_MOD, "OP_MOD", 1, opcodeDisabled},
OP_LSHIFT: {OP_LSHIFT, "OP_LSHIFT", 1, opcodeDisabled},
OP_RSHIFT: {OP_RSHIFT, "OP_RSHIFT", 1, opcodeDisabled},
OP_BOOLAND: {OP_BOOLAND, "OP_BOOLAND", 1, opcodeBoolAnd},
OP_BOOLOR: {OP_BOOLOR, "OP_BOOLOR", 1, opcodeBoolOr},
OP_NUMEQUAL: {OP_NUMEQUAL, "OP_NUMEQUAL", 1, opcodeNumEqual},
OP_NUMEQUALVERIFY: {OP_NUMEQUALVERIFY, "OP_NUMEQUALVERIFY", 1, opcodeNumEqualVerify},
OP_NUMNOTEQUAL: {OP_NUMNOTEQUAL, "OP_NUMNOTEQUAL", 1, opcodeNumNotEqual},
OP_LESSTHAN: {OP_LESSTHAN, "OP_LESSTHAN", 1, opcodeLessThan},
OP_GREATERTHAN: {OP_GREATERTHAN, "OP_GREATERTHAN", 1, opcodeGreaterThan},
OP_LESSTHANOREQUAL: {OP_LESSTHANOREQUAL, "OP_LESSTHANOREQUAL", 1, opcodeLessThanOrEqual},
OP_GREATERTHANOREQUAL: {OP_GREATERTHANOREQUAL, "OP_GREATERTHANOREQUAL", 1, opcodeGreaterThanOrEqual},
OP_MIN: {OP_MIN, "OP_MIN", 1, opcodeMin},
OP_MAX: {OP_MAX, "OP_MAX", 1, opcodeMax},
OP_WITHIN: {OP_WITHIN, "OP_WITHIN", 1, opcodeWithin},
// Crypto opcodes.
OP_RIPEMD160: {OP_RIPEMD160, "OP_RIPEMD160", 1, opcodeRipemd160},
OP_SHA1: {OP_SHA1, "OP_SHA1", 1, opcodeSha1},
OP_SHA256: {OP_SHA256, "OP_SHA256", 1, opcodeSha256},
OP_HASH160: {OP_HASH160, "OP_HASH160", 1, opcodeHash160},
OP_HASH256: {OP_HASH256, "OP_HASH256", 1, opcodeHash256},
OP_CODESEPARATOR: {OP_CODESEPARATOR, "OP_CODESEPARATOR", 1, opcodeCodeSeparator},
OP_CHECKSIG: {OP_CHECKSIG, "OP_CHECKSIG", 1, opcodeCheckSig},
OP_CHECKSIGVERIFY: {OP_CHECKSIGVERIFY, "OP_CHECKSIGVERIFY", 1, opcodeCheckSigVerify},
OP_CHECKMULTISIG: {OP_CHECKMULTISIG, "OP_CHECKMULTISIG", 1, opcodeCheckMultiSig},
OP_CHECKMULTISIGVERIFY: {OP_CHECKMULTISIGVERIFY, "OP_CHECKMULTISIGVERIFY", 1, opcodeCheckMultiSigVerify},
// Reserved opcodes.
OP_NOP1: {OP_NOP1, "OP_NOP1", 1, opcodeNop},
OP_NOP4: {OP_NOP4, "OP_NOP4", 1, opcodeNop},
OP_NOP5: {OP_NOP5, "OP_NOP5", 1, opcodeNop},
OP_NOP6: {OP_NOP6, "OP_NOP6", 1, opcodeNop},
OP_NOP7: {OP_NOP7, "OP_NOP7", 1, opcodeNop},
OP_NOP8: {OP_NOP8, "OP_NOP8", 1, opcodeNop},
OP_NOP9: {OP_NOP9, "OP_NOP9", 1, opcodeNop},
OP_NOP10: {OP_NOP10, "OP_NOP10", 1, opcodeNop},
// Undefined opcodes.
OP_UNKNOWN186: {OP_UNKNOWN186, "OP_UNKNOWN186", 1, opcodeInvalid},
OP_UNKNOWN187: {OP_UNKNOWN187, "OP_UNKNOWN187", 1, opcodeInvalid},
OP_UNKNOWN188: {OP_UNKNOWN188, "OP_UNKNOWN188", 1, opcodeInvalid},
OP_UNKNOWN189: {OP_UNKNOWN189, "OP_UNKNOWN189", 1, opcodeInvalid},
OP_UNKNOWN190: {OP_UNKNOWN190, "OP_UNKNOWN190", 1, opcodeInvalid},
OP_UNKNOWN191: {OP_UNKNOWN191, "OP_UNKNOWN191", 1, opcodeInvalid},
OP_UNKNOWN192: {OP_UNKNOWN192, "OP_UNKNOWN192", 1, opcodeInvalid},
OP_UNKNOWN193: {OP_UNKNOWN193, "OP_UNKNOWN193", 1, opcodeInvalid},
OP_UNKNOWN194: {OP_UNKNOWN194, "OP_UNKNOWN194", 1, opcodeInvalid},
OP_UNKNOWN195: {OP_UNKNOWN195, "OP_UNKNOWN195", 1, opcodeInvalid},
OP_UNKNOWN196: {OP_UNKNOWN196, "OP_UNKNOWN196", 1, opcodeInvalid},
OP_UNKNOWN197: {OP_UNKNOWN197, "OP_UNKNOWN197", 1, opcodeInvalid},
OP_UNKNOWN198: {OP_UNKNOWN198, "OP_UNKNOWN198", 1, opcodeInvalid},
OP_UNKNOWN199: {OP_UNKNOWN199, "OP_UNKNOWN199", 1, opcodeInvalid},
OP_UNKNOWN200: {OP_UNKNOWN200, "OP_UNKNOWN200", 1, opcodeInvalid},
OP_UNKNOWN201: {OP_UNKNOWN201, "OP_UNKNOWN201", 1, opcodeInvalid},
OP_UNKNOWN202: {OP_UNKNOWN202, "OP_UNKNOWN202", 1, opcodeInvalid},
OP_UNKNOWN203: {OP_UNKNOWN203, "OP_UNKNOWN203", 1, opcodeInvalid},
OP_UNKNOWN204: {OP_UNKNOWN204, "OP_UNKNOWN204", 1, opcodeInvalid},
OP_UNKNOWN205: {OP_UNKNOWN205, "OP_UNKNOWN205", 1, opcodeInvalid},
OP_UNKNOWN206: {OP_UNKNOWN206, "OP_UNKNOWN206", 1, opcodeInvalid},
OP_UNKNOWN207: {OP_UNKNOWN207, "OP_UNKNOWN207", 1, opcodeInvalid},
OP_UNKNOWN208: {OP_UNKNOWN208, "OP_UNKNOWN208", 1, opcodeInvalid},
OP_UNKNOWN209: {OP_UNKNOWN209, "OP_UNKNOWN209", 1, opcodeInvalid},
OP_UNKNOWN210: {OP_UNKNOWN210, "OP_UNKNOWN210", 1, opcodeInvalid},
OP_UNKNOWN211: {OP_UNKNOWN211, "OP_UNKNOWN211", 1, opcodeInvalid},
OP_UNKNOWN212: {OP_UNKNOWN212, "OP_UNKNOWN212", 1, opcodeInvalid},
OP_UNKNOWN213: {OP_UNKNOWN213, "OP_UNKNOWN213", 1, opcodeInvalid},
OP_UNKNOWN214: {OP_UNKNOWN214, "OP_UNKNOWN214", 1, opcodeInvalid},
OP_UNKNOWN215: {OP_UNKNOWN215, "OP_UNKNOWN215", 1, opcodeInvalid},
OP_UNKNOWN216: {OP_UNKNOWN216, "OP_UNKNOWN216", 1, opcodeInvalid},
OP_UNKNOWN217: {OP_UNKNOWN217, "OP_UNKNOWN217", 1, opcodeInvalid},
OP_UNKNOWN218: {OP_UNKNOWN218, "OP_UNKNOWN218", 1, opcodeInvalid},
OP_UNKNOWN219: {OP_UNKNOWN219, "OP_UNKNOWN219", 1, opcodeInvalid},
OP_UNKNOWN220: {OP_UNKNOWN220, "OP_UNKNOWN220", 1, opcodeInvalid},
OP_UNKNOWN221: {OP_UNKNOWN221, "OP_UNKNOWN221", 1, opcodeInvalid},
OP_UNKNOWN222: {OP_UNKNOWN222, "OP_UNKNOWN222", 1, opcodeInvalid},
OP_UNKNOWN223: {OP_UNKNOWN223, "OP_UNKNOWN223", 1, opcodeInvalid},
OP_UNKNOWN224: {OP_UNKNOWN224, "OP_UNKNOWN224", 1, opcodeInvalid},
OP_UNKNOWN225: {OP_UNKNOWN225, "OP_UNKNOWN225", 1, opcodeInvalid},
OP_UNKNOWN226: {OP_UNKNOWN226, "OP_UNKNOWN226", 1, opcodeInvalid},
OP_UNKNOWN227: {OP_UNKNOWN227, "OP_UNKNOWN227", 1, opcodeInvalid},
OP_UNKNOWN228: {OP_UNKNOWN228, "OP_UNKNOWN228", 1, opcodeInvalid},
OP_UNKNOWN229: {OP_UNKNOWN229, "OP_UNKNOWN229", 1, opcodeInvalid},
OP_UNKNOWN230: {OP_UNKNOWN230, "OP_UNKNOWN230", 1, opcodeInvalid},
OP_UNKNOWN231: {OP_UNKNOWN231, "OP_UNKNOWN231", 1, opcodeInvalid},
OP_UNKNOWN232: {OP_UNKNOWN232, "OP_UNKNOWN232", 1, opcodeInvalid},
OP_UNKNOWN233: {OP_UNKNOWN233, "OP_UNKNOWN233", 1, opcodeInvalid},
OP_UNKNOWN234: {OP_UNKNOWN234, "OP_UNKNOWN234", 1, opcodeInvalid},
OP_UNKNOWN235: {OP_UNKNOWN235, "OP_UNKNOWN235", 1, opcodeInvalid},
OP_UNKNOWN236: {OP_UNKNOWN236, "OP_UNKNOWN236", 1, opcodeInvalid},
OP_UNKNOWN237: {OP_UNKNOWN237, "OP_UNKNOWN237", 1, opcodeInvalid},
OP_UNKNOWN238: {OP_UNKNOWN238, "OP_UNKNOWN238", 1, opcodeInvalid},
OP_UNKNOWN239: {OP_UNKNOWN239, "OP_UNKNOWN239", 1, opcodeInvalid},
OP_UNKNOWN240: {OP_UNKNOWN240, "OP_UNKNOWN240", 1, opcodeInvalid},
OP_UNKNOWN241: {OP_UNKNOWN241, "OP_UNKNOWN241", 1, opcodeInvalid},
OP_UNKNOWN242: {OP_UNKNOWN242, "OP_UNKNOWN242", 1, opcodeInvalid},
OP_UNKNOWN243: {OP_UNKNOWN243, "OP_UNKNOWN243", 1, opcodeInvalid},
OP_UNKNOWN244: {OP_UNKNOWN244, "OP_UNKNOWN244", 1, opcodeInvalid},
OP_UNKNOWN245: {OP_UNKNOWN245, "OP_UNKNOWN245", 1, opcodeInvalid},
OP_UNKNOWN246: {OP_UNKNOWN246, "OP_UNKNOWN246", 1, opcodeInvalid},
OP_UNKNOWN247: {OP_UNKNOWN247, "OP_UNKNOWN247", 1, opcodeInvalid},
OP_UNKNOWN248: {OP_UNKNOWN248, "OP_UNKNOWN248", 1, opcodeInvalid},
OP_UNKNOWN249: {OP_UNKNOWN249, "OP_UNKNOWN249", 1, opcodeInvalid},
// Bitcoin Core internal use opcode. Defined here for completeness.
OP_SMALLINTEGER: {OP_SMALLINTEGER, "OP_SMALLINTEGER", 1, opcodeInvalid},
OP_PUBKEYS: {OP_PUBKEYS, "OP_PUBKEYS", 1, opcodeInvalid},
OP_UNKNOWN252: {OP_UNKNOWN252, "OP_UNKNOWN252", 1, opcodeInvalid},
OP_PUBKEYHASH: {OP_PUBKEYHASH, "OP_PUBKEYHASH", 1, opcodeInvalid},
OP_PUBKEY: {OP_PUBKEY, "OP_PUBKEY", 1, opcodeInvalid},
OP_INVALIDOPCODE: {OP_INVALIDOPCODE, "OP_INVALIDOPCODE", 1, opcodeInvalid},
}
// opcodeOnelineRepls defines opcode names which are replaced when doing a
// one-line disassembly. This is done to match the output of the reference
// implementation while not changing the opcode names in the nicer full
// disassembly.
var opcodeOnelineRepls = map[string]string{
"OP_1NEGATE": "-1",
"OP_0": "0",
"OP_1": "1",
"OP_2": "2",
"OP_3": "3",
"OP_4": "4",
"OP_5": "5",
"OP_6": "6",
"OP_7": "7",
"OP_8": "8",
"OP_9": "9",
"OP_10": "10",
"OP_11": "11",
"OP_12": "12",
"OP_13": "13",
"OP_14": "14",
"OP_15": "15",
"OP_16": "16",
}
// disasmOpcode writes a human-readable disassembly of the provided opcode and
// data into the provided buffer. The compact flag indicates the disassembly
// should print a more compact representation of data-carrying and small integer
// opcodes. For example, OP_0 through OP_16 are replaced with the numeric value
// and data pushes are printed as only the hex representation of the data as
// opposed to including the opcode that specifies the amount of data to push as
// well.
func disasmOpcode(buf *strings.Builder, op *opcode, data []byte, compact bool) {
// Replace opcode which represent values (e.g. OP_0 through OP_16 and
// OP_1NEGATE) with the raw value when performing a compact disassembly.
opcodeName := op.name
if compact {
if replName, ok := opcodeOnelineRepls[opcodeName]; ok {
opcodeName = replName
}
// Either write the human-readable opcode or the parsed data in hex for
// data-carrying opcodes.
switch {
case op.length == 1:
buf.WriteString(opcodeName)
default:
buf.WriteString(hex.EncodeToString(data))
}
return
}
buf.WriteString(opcodeName)
switch op.length {
// Only write the opcode name for non-data push opcodes.
case 1:
return
// Add length for the OP_PUSHDATA# opcodes.
case -1:
buf.WriteString(fmt.Sprintf(" 0x%02x", len(data)))
case -2:
buf.WriteString(fmt.Sprintf(" 0x%04x", len(data)))
case -4:
buf.WriteString(fmt.Sprintf(" 0x%08x", len(data)))
}
buf.WriteString(fmt.Sprintf(" 0x%02x", data))
}
// *******************************************
// Opcode implementation functions start here.
// *******************************************
// opcodeDisabled is a common handler for disabled opcodes. It returns an
// appropriate error indicating the opcode is disabled. While it would
// ordinarily make more sense to detect if the script contains any disabled
// opcodes before executing in an initial parse step, the consensus rules
// dictate the script doesn't fail until the program counter passes over a
// disabled opcode (even when they appear in a branch that is not executed).
func opcodeDisabled(op *opcode, data []byte, vm *Engine) error {
str := fmt.Sprintf("attempt to execute disabled opcode %s", op.name)
return scriptError(ErrDisabledOpcode, str)
}
// opcodeReserved is a common handler for all reserved opcodes. It returns an
// appropriate error indicating the opcode is reserved.
func opcodeReserved(op *opcode, data []byte, vm *Engine) error {
str := fmt.Sprintf("attempt to execute reserved opcode %s", op.name)
return scriptError(ErrReservedOpcode, str)
}
// opcodeInvalid is a common handler for all invalid opcodes. It returns an
// appropriate error indicating the opcode is invalid.
func opcodeInvalid(op *opcode, data []byte, vm *Engine) error {
str := fmt.Sprintf("attempt to execute invalid opcode %s", op.name)
return scriptError(ErrReservedOpcode, str)
}
// opcodeFalse pushes an empty array to the data stack to represent false. Note
// that 0, when encoded as a number according to the numeric encoding consensus
// rules, is an empty array.
func opcodeFalse(op *opcode, data []byte, vm *Engine) error {
vm.dstack.PushByteArray(nil)
return nil
}
// opcodePushData is a common handler for the vast majority of opcodes that push
// raw data (bytes) to the data stack.
func opcodePushData(op *opcode, data []byte, vm *Engine) error {
vm.dstack.PushByteArray(data)
return nil
}
// opcode1Negate pushes -1, encoded as a number, to the data stack.
func opcode1Negate(op *opcode, data []byte, vm *Engine) error {
vm.dstack.PushInt(scriptNum(-1))
return nil
}
// opcodeN is a common handler for the small integer data push opcodes. It
// pushes the numeric value the opcode represents (which will be from 1 to 16)
// onto the data stack.
func opcodeN(op *opcode, data []byte, vm *Engine) error {
// The opcodes are all defined consecutively, so the numeric value is
// the difference.
vm.dstack.PushInt(scriptNum((op.value - (OP_1 - 1))))
return nil
}
// opcodeNop is a common handler for the NOP family of opcodes. As the name
// implies it generally does nothing, however, it will return an error when
// the flag to discourage use of NOPs is set for select opcodes.
func opcodeNop(op *opcode, data []byte, vm *Engine) error {
switch op.value {
case OP_NOP1, OP_NOP4, OP_NOP5,
OP_NOP6, OP_NOP7, OP_NOP8, OP_NOP9, OP_NOP10:
if vm.hasFlag(ScriptDiscourageUpgradableNops) {
str := fmt.Sprintf("%v reserved for soft-fork "+
"upgrades", op.name)
return scriptError(ErrDiscourageUpgradableNOPs, str)
}
}
return nil
}
// popIfBool enforces the "minimal if" policy during script execution if the
// particular flag is set. If so, in order to eliminate an additional source
// of nuisance malleability, post-segwit for version 0 witness programs, we now
// require the following: for OP_IF and OP_NOT_IF, the top stack item MUST
// either be an empty byte slice, or [0x01]. Otherwise, the item at the top of
// the stack will be popped and interpreted as a boolean.
func popIfBool(vm *Engine) (bool, error) {
// When not in witness execution mode, not executing a v0 witness
// program, or the minimal if flag isn't set pop the top stack item as
// a normal bool.
if !vm.isWitnessVersionActive(0) || !vm.hasFlag(ScriptVerifyMinimalIf) {
return vm.dstack.PopBool()
}
// At this point, a v0 witness program is being executed and the minimal
// if flag is set, so enforce additional constraints on the top stack
// item.
so, err := vm.dstack.PopByteArray()
if err != nil {
return false, err
}
// The top element MUST have a length of at least one.
if len(so) > 1 {
str := fmt.Sprintf("minimal if is active, top element MUST "+
"have a length of at least, instead length is %v",
len(so))
return false, scriptError(ErrMinimalIf, str)
}
// Additionally, if the length is one, then the value MUST be 0x01.
if len(so) == 1 && so[0] != 0x01 {
str := fmt.Sprintf("minimal if is active, top stack item MUST "+
"be an empty byte array or 0x01, is instead: %v",
so[0])
return false, scriptError(ErrMinimalIf, str)
}
return asBool(so), nil
}
// opcodeIf treats the top item on the data stack as a boolean and removes it.
//
// An appropriate entry is added to the conditional stack depending on whether
// the boolean is true and whether this if is on an executing branch in order
// to allow proper execution of further opcodes depending on the conditional
// logic. When the boolean is true, the first branch will be executed (unless
// this opcode is nested in a non-executed branch).
//
// <expression> if [statements] [else [statements]] endif
//
// Note that, unlike for all non-conditional opcodes, this is executed even when
// it is on a non-executing branch so proper nesting is maintained.
//
// Data stack transformation: [... bool] -> [...]
// Conditional stack transformation: [...] -> [... OpCondValue]
func opcodeIf(op *opcode, data []byte, vm *Engine) error {
condVal := OpCondFalse
if vm.isBranchExecuting() {
ok, err := popIfBool(vm)
if err != nil {
return err
}
if ok {
condVal = OpCondTrue
}
} else {
condVal = OpCondSkip
}
vm.condStack = append(vm.condStack, condVal)
return nil
}
// opcodeNotIf treats the top item on the data stack as a boolean and removes
// it.
//
// An appropriate entry is added to the conditional stack depending on whether
// the boolean is true and whether this if is on an executing branch in order
// to allow proper execution of further opcodes depending on the conditional
// logic. When the boolean is false, the first branch will be executed (unless
// this opcode is nested in a non-executed branch).
//
// <expression> notif [statements] [else [statements]] endif
//
// Note that, unlike for all non-conditional opcodes, this is executed even when
// it is on a non-executing branch so proper nesting is maintained.
//
// Data stack transformation: [... bool] -> [...]
// Conditional stack transformation: [...] -> [... OpCondValue]
func opcodeNotIf(op *opcode, data []byte, vm *Engine) error {
condVal := OpCondFalse
if vm.isBranchExecuting() {
ok, err := popIfBool(vm)
if err != nil {
return err
}
if !ok {
condVal = OpCondTrue
}
} else {
condVal = OpCondSkip
}
vm.condStack = append(vm.condStack, condVal)
return nil
}
// opcodeElse inverts conditional execution for other half of if/else/endif.
//
// An error is returned if there has not already been a matching OP_IF.
//
// Conditional stack transformation: [... OpCondValue] -> [... !OpCondValue]
func opcodeElse(op *opcode, data []byte, vm *Engine) error {
if len(vm.condStack) == 0 {
str := fmt.Sprintf("encountered opcode %s with no matching "+
"opcode to begin conditional execution", op.name)
return scriptError(ErrUnbalancedConditional, str)
}
conditionalIdx := len(vm.condStack) - 1
switch vm.condStack[conditionalIdx] {
case OpCondTrue:
vm.condStack[conditionalIdx] = OpCondFalse
case OpCondFalse:
vm.condStack[conditionalIdx] = OpCondTrue
case OpCondSkip:
// Value doesn't change in skip since it indicates this opcode
// is nested in a non-executed branch.
}
return nil
}
// opcodeEndif terminates a conditional block, removing the value from the
// conditional execution stack.
//
// An error is returned if there has not already been a matching OP_IF.
//
// Conditional stack transformation: [... OpCondValue] -> [...]
func opcodeEndif(op *opcode, data []byte, vm *Engine) error {
if len(vm.condStack) == 0 {
str := fmt.Sprintf("encountered opcode %s with no matching "+
"opcode to begin conditional execution", op.name)
return scriptError(ErrUnbalancedConditional, str)
}
vm.condStack = vm.condStack[:len(vm.condStack)-1]
return nil
}
// abstractVerify examines the top item on the data stack as a boolean value and
// verifies it evaluates to true. An error is returned either when there is no
// item on the stack or when that item evaluates to false. In the latter case
// where the verification fails specifically due to the top item evaluating
// to false, the returned error will use the passed error code.
func abstractVerify(op *opcode, vm *Engine, c ErrorCode) error {
verified, err := vm.dstack.PopBool()
if err != nil {
return err
}
if !verified {
str := fmt.Sprintf("%s failed", op.name)
return scriptError(c, str)
}
return nil
}
// opcodeVerify examines the top item on the data stack as a boolean value and
// verifies it evaluates to true. An error is returned if it does not.
func opcodeVerify(op *opcode, data []byte, vm *Engine) error {
return abstractVerify(op, vm, ErrVerify)
}
// opcodeReturn returns an appropriate error since it is always an error to
// return early from a script.
func opcodeReturn(op *opcode, data []byte, vm *Engine) error {
return scriptError(ErrEarlyReturn, "script returned early")
}
// verifyLockTime is a helper function used to validate locktimes.
func verifyLockTime(txLockTime, threshold, lockTime int64) error {
// The lockTimes in both the script and transaction must be of the same
// type.
if !((txLockTime < threshold && lockTime < threshold) ||
(txLockTime >= threshold && lockTime >= threshold)) {
str := fmt.Sprintf("mismatched locktime types -- tx locktime "+
"%d, stack locktime %d", txLockTime, lockTime)
return scriptError(ErrUnsatisfiedLockTime, str)
}
if lockTime > txLockTime {
str := fmt.Sprintf("locktime requirement not satisfied -- "+
"locktime is greater than the transaction locktime: "+
"%d > %d", lockTime, txLockTime)
return scriptError(ErrUnsatisfiedLockTime, str)
}
return nil
}
// opcodeCheckLockTimeVerify compares the top item on the data stack to the
// LockTime field of the transaction containing the script signature
// validating if the transaction outputs are spendable yet. If flag
// ScriptVerifyCheckLockTimeVerify is not set, the code continues as if OP_NOP2
// were executed.
func opcodeCheckLockTimeVerify(op *opcode, data []byte, vm *Engine) error {
// If the ScriptVerifyCheckLockTimeVerify script flag is not set, treat
// opcode as OP_NOP2 instead.
if !vm.hasFlag(ScriptVerifyCheckLockTimeVerify) {
if vm.hasFlag(ScriptDiscourageUpgradableNops) {
return scriptError(ErrDiscourageUpgradableNOPs,
"OP_NOP2 reserved for soft-fork upgrades")
}
return nil
}
// The current transaction locktime is a uint32 resulting in a maximum
// locktime of 2^32-1 (the year 2106). However, scriptNums are signed
// and therefore a standard 4-byte scriptNum would only support up to a
// maximum of 2^31-1 (the year 2038). Thus, a 5-byte scriptNum is used
// here since it will support up to 2^39-1 which allows dates beyond the
// current locktime limit.
//
// PeekByteArray is used here instead of PeekInt because we do not want
// to be limited to a 4-byte integer for reasons specified above.
so, err := vm.dstack.PeekByteArray(0)
if err != nil {
return err
}
lockTime, err := makeScriptNum(so, vm.dstack.verifyMinimalData, 5)
if err != nil {
return err
}
// In the rare event that the argument needs to be < 0 due to some
// arithmetic being done first, you can always use
// 0 OP_MAX OP_CHECKLOCKTIMEVERIFY.
if lockTime < 0 {
str := fmt.Sprintf("negative lock time: %d", lockTime)
return scriptError(ErrNegativeLockTime, str)
}
// The lock time field of a transaction is either a block height at
// which the transaction is finalized or a timestamp depending on if the
// value is before the txscript.LockTimeThreshold. When it is under the
// threshold it is a block height.
err = verifyLockTime(int64(vm.tx.LockTime), LockTimeThreshold,
int64(lockTime))
if err != nil {
return err
}
// The lock time feature can also be disabled, thereby bypassing
// OP_CHECKLOCKTIMEVERIFY, if every transaction input has been finalized by
// setting its sequence to the maximum value (wire.MaxTxInSequenceNum). This
// condition would result in the transaction being allowed into the blockchain
// making the opcode ineffective.
//
// This condition is prevented by enforcing that the input being used by
// the opcode is unlocked (its sequence number is less than the max
// value). This is sufficient to prove correctness without having to