Class: Bitcoin::ScriptInterpreter

Inherits:
Object
  • Object
show all
Includes:
Opcodes
Defined in:
lib/bitcoin/script/script_interpreter.rb

Constant Summary collapse

DISABLE_OPCODES = 
[OP_CAT, OP_SUBSTR, OP_LEFT, OP_RIGHT, OP_INVERT, OP_AND, OP_OR, OP_XOR, OP_2MUL, OP_2DIV, OP_DIV, OP_MUL, OP_MOD, OP_LSHIFT, OP_RSHIFT]

Constants included from Opcodes

Opcodes::DUPLICATE_KEY, Opcodes::NAME_MAP, Opcodes::OPCODES_MAP, Opcodes::OP_0, Opcodes::OP_0NOTEQUAL, Opcodes::OP_1, Opcodes::OP_10, Opcodes::OP_11, Opcodes::OP_12, Opcodes::OP_13, Opcodes::OP_14, Opcodes::OP_15, Opcodes::OP_16, Opcodes::OP_1ADD, Opcodes::OP_1NEGATE, Opcodes::OP_1SUB, Opcodes::OP_2, Opcodes::OP_2DIV, Opcodes::OP_2DROP, Opcodes::OP_2DUP, Opcodes::OP_2MUL, Opcodes::OP_2OVER, Opcodes::OP_2ROT, Opcodes::OP_2SWAP, Opcodes::OP_3, Opcodes::OP_3DUP, Opcodes::OP_4, Opcodes::OP_5, Opcodes::OP_6, Opcodes::OP_7, Opcodes::OP_8, Opcodes::OP_9, Opcodes::OP_ABS, Opcodes::OP_ADD, Opcodes::OP_AND, Opcodes::OP_BOOLAND, Opcodes::OP_BOOLOR, Opcodes::OP_CAT, Opcodes::OP_CHECKMULTISIG, Opcodes::OP_CHECKMULTISIGVERIFY, Opcodes::OP_CHECKSIG, Opcodes::OP_CHECKSIGADD, Opcodes::OP_CHECKSIGVERIFY, Opcodes::OP_CODESEPARATOR, Opcodes::OP_DEPTH, Opcodes::OP_DIV, Opcodes::OP_DROP, Opcodes::OP_DUP, Opcodes::OP_ELSE, Opcodes::OP_ENDIF, Opcodes::OP_EQUAL, Opcodes::OP_EQUALVERIFY, Opcodes::OP_FROMALTSTACK, Opcodes::OP_GREATERTHAN, Opcodes::OP_GREATERTHANOREQUAL, Opcodes::OP_HASH160, Opcodes::OP_HASH256, Opcodes::OP_IF, Opcodes::OP_IFDUP, Opcodes::OP_INVALIDOPCODE, Opcodes::OP_INVERT, Opcodes::OP_LEFT, Opcodes::OP_LESSTHAN, Opcodes::OP_LESSTHANOREQUAL, Opcodes::OP_LSHIFT, Opcodes::OP_MAX, Opcodes::OP_MIN, Opcodes::OP_MOD, Opcodes::OP_MUL, Opcodes::OP_NEGATE, Opcodes::OP_NIP, Opcodes::OP_NOP, Opcodes::OP_NOP1, Opcodes::OP_NOP10, Opcodes::OP_NOP2, Opcodes::OP_NOP3, Opcodes::OP_NOP4, Opcodes::OP_NOP5, Opcodes::OP_NOP6, Opcodes::OP_NOP7, Opcodes::OP_NOP8, Opcodes::OP_NOP9, Opcodes::OP_NOT, Opcodes::OP_NOTIF, Opcodes::OP_NUMEQUAL, Opcodes::OP_NUMEQUALVERIFY, Opcodes::OP_NUMNOTEQUAL, Opcodes::OP_OR, Opcodes::OP_OVER, Opcodes::OP_PICK, Opcodes::OP_PUBKEY, Opcodes::OP_PUBKEYHASH, Opcodes::OP_PUSHDATA1, Opcodes::OP_PUSHDATA2, Opcodes::OP_PUSHDATA4, Opcodes::OP_RESERVED, Opcodes::OP_RESERVED1, Opcodes::OP_RESERVED2, Opcodes::OP_RETURN, Opcodes::OP_RIGHT, Opcodes::OP_RIPEMD160, Opcodes::OP_ROLL, Opcodes::OP_ROT, Opcodes::OP_RSHIFT, Opcodes::OP_SHA1, Opcodes::OP_SHA256, Opcodes::OP_SIZE, Opcodes::OP_SUB, Opcodes::OP_SUBSTR, Opcodes::OP_SUCCESSES, Opcodes::OP_SWAP, Opcodes::OP_TOALTSTACK, Opcodes::OP_TUCK, Opcodes::OP_VER, Opcodes::OP_VERIF, Opcodes::OP_VERIFY, Opcodes::OP_VERNOTIF, Opcodes::OP_WITHIN, Opcodes::OP_XOR

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Opcodes

defined?, name_to_opcode, op_success?, opcode_to_name, opcode_to_small_int, small_int_to_opcode

Constructor Details

#initialize(flags: SCRIPT_VERIFY_NONE, checker: TxChecker.new) ⇒ ScriptInterpreter

initialize runner



25
26
27
28
29
30
 
# File 'lib/bitcoin/script/script_interpreter.rb', line 25

def initialize(flags: SCRIPT_VERIFY_NONE, checker: TxChecker.new)
  @stack, @debug = [], []
  @flags = flags
  @checker = checker
  @require_minimal = flag?(SCRIPT_VERIFY_MINIMALDATA)
end

Instance Attribute Details

#checker ⇒ Object (readonly)

Returns the value of attribute checker.



12
13
14
 
# File 'lib/bitcoin/script/script_interpreter.rb', line 12

def checker
  @checker
end

#debug ⇒ Object (readonly)

Returns the value of attribute debug.



9
10
11
 
# File 'lib/bitcoin/script/script_interpreter.rb', line 9

def debug
  @debug
end

#error ⇒ Object

Returns the value of attribute error.



11
12
13
 
# File 'lib/bitcoin/script/script_interpreter.rb', line 11

def error
  @error
end

#flags ⇒ Object (readonly)

Returns the value of attribute flags.



10
11
12
 
# File 'lib/bitcoin/script/script_interpreter.rb', line 10

def flags
  @flags
end

#require_minimal ⇒ Object (readonly)

Returns the value of attribute require_minimal.



13
14
15
 
# File 'lib/bitcoin/script/script_interpreter.rb', line 13

def require_minimal
  @require_minimal
end

#stack ⇒ Object (readonly)

Returns the value of attribute stack.



8
9
10
 
# File 'lib/bitcoin/script/script_interpreter.rb', line 8

def stack
  @stack
end

Class Method Details

.eval(script_sig, script_pubkey) ⇒ Object

syntax sugar for simple evaluation for script.

Parameters:



20
21
22
 
# File 'lib/bitcoin/script/script_interpreter.rb', line 20

def self.eval(script_sig, script_pubkey)
  self.new.verify_script(script_sig, script_pubkey)
end

Instance Method Details

#eval_script(script, sig_version, opts: {}) ⇒ Object

Raises:

  • (ArgumentError) 


187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
 
# File 'lib/bitcoin/script/script_interpreter.rb', line 187

def eval_script(script, sig_version, opts: {})
  # sig_version cannot be TAPROOT here, as it admits no script execution.
  raise ArgumentError, "Invalid sig version was specified: #{sig_version}" unless [:base, :witness_v0, :tapscript].include?(sig_version)
  return set_error(SCRIPT_ERR_SCRIPT_SIZE) if script.size > MAX_SCRIPT_SIZE && [:base, :witness_v0].include?(sig_version)
  begin
    flow_stack = []
    alt_stack = []
    opts[:last_code_separator_pos] = 0xffffffff
    opts[:begincodehash] = 0
    op_count = 0

    script.chunks.each_with_index do |c, index|
      need_exec = flow_stack.rindex(false).nil?

      return set_error(SCRIPT_ERR_PUSH_SIZE) if c.pushdata? && c.pushed_data.bytesize > MAX_SCRIPT_ELEMENT_SIZE

      opcode = c.opcode

      if need_exec && c.pushdata?
        if require_minimal && !minimal_push?(c.pushed_data, opcode)
          return set_error(SCRIPT_ERR_MINIMALDATA)
        end
        return set_error(SCRIPT_ERR_BAD_OPCODE) unless c.valid_pushdata_length?
        stack << c.pushed_data.bth
      else
        if [:base, :witness_v0].include?(sig_version) && opcode > OP_16 && (op_count += 1) > MAX_OPS_PER_SCRIPT
          return set_error(SCRIPT_ERR_OP_COUNT)
        end
        return set_error(SCRIPT_ERR_DISABLED_OPCODE) if DISABLE_OPCODES.include?(opcode)
        return set_error(SCRIPT_ERR_OP_CODESEPARATOR) if opcode == OP_CODESEPARATOR && sig_version == :base && flag?(SCRIPT_VERIFY_CONST_SCRIPTCODE)
        next unless (need_exec || (OP_IF <= opcode && opcode <= OP_ENDIF))
        small_int = Opcodes.opcode_to_small_int(opcode)
        if small_int && opcode != OP_0
          push_int(small_int)
        else
          case opcode
            when OP_0
              stack << ''
            when OP_DEPTH
              push_int(stack.size)
            when OP_EQUAL, OP_EQUALVERIFY
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 2
              a, b = pop_string(2)
              result = a == b
              push_int(result ? 1 : 0)
              if opcode == OP_EQUALVERIFY
                if result
                  stack.pop
                else
                  return set_error(SCRIPT_ERR_EQUALVERIFY)
                end
              end
            when OP_0NOTEQUAL
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 1
              push_int(pop_int == 0 ? 0 : 1)
            when OP_ADD
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 2
              a, b = pop_int(2)
              push_int(a + b)
            when OP_1ADD
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 1
              push_int(pop_int + 1)
            when OP_SUB
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 2
              a, b = pop_int(2)
              push_int(a - b)
            when OP_1SUB
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 1
              push_int(pop_int - 1)
            when OP_IF, OP_NOTIF
              result = false
              if need_exec
                return set_error(SCRIPT_ERR_UNBALANCED_CONDITIONAL) if stack.size < 1
                value = pop_string.htb
                if sig_version == :witness_v0 && flag?(SCRIPT_VERIFY_MINIMALIF) || sig_version == :tapscript
                  # Under witness v0 rules it is only a policy rule, enabled through SCRIPT_VERIFY_MINIMALIF.
                  # Tapscript requires minimal IF/NOTIF inputs as a consensus rule.
                  if value.bytesize > 1 || (value.bytesize == 1 && value[0].unpack1('C') != 1)
                    return set_error(sig_version == :witness_v0 ? SCRIPT_ERR_MINIMALIF : SCRIPT_ERR_TAPSCRIPT_MINIMALIF)
                  end
                end
                result = cast_to_bool(value)
                result = !result if opcode == OP_NOTIF
              end
              flow_stack << result
            when OP_ELSE
              return set_error(SCRIPT_ERR_UNBALANCED_CONDITIONAL) if flow_stack.size < 1
              flow_stack << !flow_stack.pop
            when OP_ENDIF
              return set_error(SCRIPT_ERR_UNBALANCED_CONDITIONAL) if flow_stack.empty?
              flow_stack.pop
            when OP_NOP
            when OP_NOP1, OP_NOP4..OP_NOP10
              return set_error(SCRIPT_ERR_DISCOURAGE_UPGRADABLE_NOPS) if flag?(SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_NOPS)
            when OP_CHECKLOCKTIMEVERIFY
              next unless flag?(SCRIPT_VERIFY_CHECKLOCKTIMEVERIFY)
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 1
              # Note that elsewhere numeric opcodes are limited to operands in the range -2**31+1 to 2**31-1,
              # however it is legal for opcodes to produce results exceeding that range.
              # This limitation is implemented by CScriptNum's default 4-byte limit.
              # If we kept to that limit we'd have a year 2038 problem,
              # even though the nLockTime field in transactions themselves is uint32 which only becomes meaningless after the year 2106.
              # Thus as a special case we tell CScriptNum to accept up to 5-byte bignums,
              # which are good until 2**39-1, well beyond the 2**32-1 limit of the nLockTime field itself.
              locktime = cast_to_int(stack.last, 5)
              return set_error(SCRIPT_ERR_NEGATIVE_LOCKTIME) if locktime < 0
              return set_error(SCRIPT_ERR_UNSATISFIED_LOCKTIME) unless checker.check_locktime(locktime)
            when OP_CHECKSEQUENCEVERIFY
              next unless flag?(SCRIPT_VERIFY_CHECKSEQUENCEVERIFY)
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 1

              # nSequence, like nLockTime, is a 32-bit unsigned integer field.
              # See the comment in CHECKLOCKTIMEVERIFY regarding 5-byte numeric operands.
              sequence = cast_to_int(stack.last, 5)

              # In the rare event that the argument may be < 0 due to some arithmetic being done first,
              # you can always use 0 MAX CHECKSEQUENCEVERIFY.
              return set_error(SCRIPT_ERR_NEGATIVE_LOCKTIME) if sequence < 0

              # To provide for future soft-fork extensibility,
              # if the operand has the disabled lock-time flag set, CHECKSEQUENCEVERIFY behaves as a NOP.
              next if (sequence & Bitcoin::TxIn::SEQUENCE_LOCKTIME_DISABLE_FLAG) != 0

              # Compare the specified sequence number with the input.
              unless checker.check_sequence(sequence)
                return set_error(SCRIPT_ERR_UNSATISFIED_LOCKTIME)
              end
            when OP_DUP
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 1
              stack << stack.last
            when OP_2DUP
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 2
              2.times { stack << stack[-2] }
            when OP_3DUP
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 3
              3.times { stack << stack[-3] }
            when OP_IFDUP
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 1
              stack << stack.last if cast_to_bool(stack.last)
            when OP_RIPEMD160
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 1
              stack << Digest::RMD160.hexdigest(pop_string.htb)
            when OP_SHA1
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 1
              stack << Digest::SHA1.hexdigest(pop_string.htb)
            when OP_SHA256
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 1
              stack << Digest::SHA256.hexdigest(pop_string.htb)
            when OP_HASH160
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 1
              stack << Bitcoin.hash160(pop_string)
            when OP_HASH256
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 1
              stack << Bitcoin.double_sha256(pop_string.htb).bth
            when OP_VERIFY
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 1
              return set_error(SCRIPT_ERR_VERIFY) unless pop_bool
            when OP_TOALTSTACK
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 1
              alt_stack << stack.pop
            when OP_FROMALTSTACK
              return set_error(SCRIPT_ERR_INVALID_ALTSTACK_OPERATION) if alt_stack.size < 1
              stack << alt_stack.pop
            when OP_DROP
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 1
              stack.pop
            when OP_2DROP
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 2
              2.times { stack.pop }
            when OP_NIP
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 2
              stack.delete_at(-2)
            when OP_OVER
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 2
              stack << stack[-2]
            when OP_2OVER
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 4
              2.times { stack << stack[-4]}
            when OP_PICK, OP_ROLL
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 2
              pos = pop_int
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if pos < 0 || pos >= stack.size
              stack << stack[-pos - 1]
              stack.delete_at(-pos - 2) if opcode == OP_ROLL
            when OP_ROT
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 3
              stack << stack[-3]
              stack.delete_at(-4)
            when OP_2ROT
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 6
              2.times { stack << stack[-6] }
              2.times { stack.delete_at(-7) }
            when OP_SWAP
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 2
              tmp = stack.last
              stack[-1] = stack[-2]
              stack[-2] = tmp
            when OP_2SWAP
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 4
              2.times {stack << stack[-4]}
              2.times {stack.delete_at(-5)}
            when OP_TUCK
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 2
              stack.insert(-3, stack.last)
            when OP_ABS
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 1
              v = pop_int
              push_int(v.abs)
            when OP_BOOLAND
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 2
              a, b = pop_int(2)
              push_int((!a.zero? && !b.zero?) ? 1 : 0)
            when OP_BOOLOR
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 2
              a, b = pop_int(2)
              push_int((!a.zero? || !b.zero?) ? 1 : 0)
            when OP_NUMEQUAL, OP_NUMEQUALVERIFY
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 2
              a, b = pop_int(2)
              result = a == b
              push_int(result ? 1 : 0)
              if opcode == OP_NUMEQUALVERIFY
                if result
                  stack.pop
                else
                  return set_error(SCRIPT_ERR_NUMEQUALVERIFY)
                end
              end
            when OP_LESSTHAN, OP_LESSTHANOREQUAL
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 2
              a, b = pop_int(2)
              push_int(a < b ? 1 : 0) if opcode == OP_LESSTHAN
              push_int(a <= b ? 1 : 0) if opcode == OP_LESSTHANOREQUAL
            when OP_GREATERTHAN, OP_GREATERTHANOREQUAL
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 2
              a, b = pop_int(2)
              push_int(a > b ? 1 : 0) if opcode == OP_GREATERTHAN
              push_int(a >= b ? 1 : 0) if opcode == OP_GREATERTHANOREQUAL
            when OP_MIN
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 2
              push_int(pop_int(2).min)
            when OP_MAX
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 2
              push_int(pop_int(2).max)
            when OP_WITHIN
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 3
              x, a, b = pop_int(3)
              push_int((a <= x && x < b) ? 1 : 0)
            when OP_NOT
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 1
              push_int(pop_int == 0 ? 1 : 0)
            when OP_SIZE
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 1
              item = stack.last
              item = Bitcoin::Script.encode_number(item) if item.is_a?(Numeric)
              size = item.htb.bytesize
              push_int(size)
            when OP_NEGATE
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 1
              push_int(-pop_int)
            when OP_NUMNOTEQUAL
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION)  if stack.size < 2
              a, b = pop_int(2)
              push_int(a == b ? 0 : 1)
            when OP_CODESEPARATOR
              opts[:begincodehash] = index + 1
              opts[:last_code_separator_pos] = index
            when OP_CHECKSIG, OP_CHECKSIGVERIFY
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION)  if stack.size < 2
              sig, pubkey = pop_string(2)

              success = valid_sig?(sig, pubkey, sig_version, script, opts)
              return false if error && !error.ok?

              push_int(success ? 1 : 0)

              if opcode == OP_CHECKSIGVERIFY
                if success
                  stack.pop
                else
                  return set_error(SCRIPT_ERR_CHECKSIGVERIFY)
                end
              end
            when OP_CHECKSIGADD
              # OP_CHECKSIGADD is only available in Tapscript
              return set_error(SCRIPT_ERR_BAD_OPCODE) if [:base, :witness_v0].include?(sig_version)
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < 3

              pubkey = pop_string
              num = pop_int
              sig = pop_string

              success = valid_sig?(sig, pubkey, sig_version, script, opts) && !sig.empty?
              return false if error && !error.ok?

              push_int(success ? num + 1 : num)
            when OP_CHECKMULTISIG, OP_CHECKMULTISIGVERIFY
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION)  if stack.size < 1
              pubkey_count = pop_int
              unless (0..MAX_PUBKEYS_PER_MULTISIG).include?(pubkey_count)
                return set_error(SCRIPT_ERR_PUBKEY_COUNT)
              end

              op_count += pubkey_count
              return set_error(SCRIPT_ERR_OP_COUNT) if op_count > MAX_OPS_PER_SCRIPT

              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < pubkey_count

              pubkeys = pop_string(pubkey_count)
              pubkeys = [pubkeys] if pubkeys.is_a?(String)

              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION)  if stack.size < 1

              sig_count = pop_int
              return set_error(SCRIPT_ERR_SIG_COUNT) if sig_count < 0 || sig_count > pubkey_count
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION) if stack.size < (sig_count)

              sigs = pop_string(sig_count)
              sigs = [sigs] if sigs.is_a?(String)
              
              subscript = script.subscript(opts[:begincodehash]..-1)

              if sig_version == :base
                sigs.each do |sig|
                  tmp = subscript.find_and_delete(Script.new << sig)
                  return set_error(SCRIPT_ERR_SIG_FINDANDDELETE) if flag?(SCRIPT_VERIFY_CONST_SCRIPTCODE) && tmp != subscript
                  subscript = tmp
                end
              end

              success = true
              while success && sig_count > 0
                sig = sigs.pop
                pubkey = pubkeys.pop
                return false if !check_pubkey_encoding(pubkey, sig_version) || !check_signature_encoding(sig) # error already set.
                ok = checker.check_sig(sig, pubkey, subscript, sig_version, allow_hybrid: !flag?(SCRIPT_VERIFY_STRICTENC))
                if ok
                  sig_count -= 1
                else
                  sigs << sig
                end
                pubkey_count -= 1
                success = false if sig_count > pubkey_count
              end

              if !success && flag?(SCRIPT_VERIFY_NULLFAIL)
                sigs.each do |sig|
                  # If the operation failed, we require that all signatures must be empty vector
                  return set_error(SCRIPT_ERR_SIG_NULLFAIL) if sig.bytesize > 0
                end
              end

              # A bug causes CHECKMULTISIG to consume one extra argument whose contents were not checked in any way.
              # Unfortunately this is a potential source of mutability,
              # so optionally verify it is exactly equal to zero prior to removing it from the stack.
              return set_error(SCRIPT_ERR_INVALID_STACK_OPERATION)  if stack.size < 1
              if flag?(SCRIPT_VERIFY_NULLDUMMY) && stack[-1].size > 0
                return set_error(SCRIPT_ERR_SIG_NULLDUMMY)
              end
              stack.pop

              push_int(success ? 1 : 0)
              if opcode == OP_CHECKMULTISIGVERIFY
                if success
                  stack.pop
                else
                  return set_error(SCRIPT_ERR_CHECKMULTISIGVERIFY)
                end
              end
            when OP_RETURN
              return set_error(SCRIPT_ERR_OP_RETURN)
            else
              return set_error(SCRIPT_ERR_BAD_OPCODE)
          end
        end
      end

      # max stack size check
      return set_error(SCRIPT_ERR_STACK_SIZE) if stack.size + alt_stack.size > MAX_STACK_SIZE
    end
  rescue Exception => e
    puts e
    return set_error(SCRIPT_ERR_UNKNOWN_ERROR, e.message)
  end

  return set_error(SCRIPT_ERR_UNBALANCED_CONDITIONAL) unless flow_stack.empty?

  set_error(SCRIPT_ERR_OK)
  true
end

#set_error(err_code, extra_message = nil) ⇒ Object 



101
102
103
104
 
# File 'lib/bitcoin/script/script_interpreter.rb', line 101

def set_error(err_code, extra_message = nil)
  @error = ScriptError.new(err_code, extra_message)
  false
end

#verify_script(script_sig, script_pubkey, witness = ScriptWitness.new) ⇒ Boolean

eval script

Parameters:

Returns:

  • (Boolean) —

    result



37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
 
# File 'lib/bitcoin/script/script_interpreter.rb', line 37

def verify_script(script_sig, script_pubkey, witness = ScriptWitness.new)

  return set_error(SCRIPT_ERR_SIG_PUSHONLY) if flag?(SCRIPT_VERIFY_SIGPUSHONLY) && !script_sig.push_only?

  stack_copy = nil
  had_witness = false

  return false unless eval_script(script_sig, :base)

  stack_copy = stack.dup if flag?(SCRIPT_VERIFY_P2SH)

  return false unless eval_script(script_pubkey, :base)

  return set_error(SCRIPT_ERR_EVAL_FALSE) if stack.empty? || !cast_to_bool(stack.last.htb)

  # Bare witness programs
  if flag?(SCRIPT_VERIFY_WITNESS) && script_pubkey.witness_program?
    had_witness = true
    return set_error(SCRIPT_ERR_WITNESS_MALLEATED) unless script_sig.size == 0
    version, program = script_pubkey.witness_data
    stack_copy = stack.dup
    return false unless verify_witness_program(witness, version, program, false)
    # Bypass the cleanstack check at the end. The actual stack is obviously not clean for witness programs.
    stack.resize!(1, Script.encode_number(0))
  end

  # Additional validation for spend-to-script-hash transactions
  if flag?(SCRIPT_VERIFY_P2SH) && script_pubkey.p2sh?
    return set_error(SCRIPT_ERR_SIG_PUSHONLY) unless script_sig.push_only?
    @stack = stack_copy
    raise 'stack cannot be empty.' if stack.empty?
    redeem_script = Bitcoin::Script.parse_from_payload(stack.pop.htb)
    return false unless eval_script(redeem_script, :base)
    return set_error(SCRIPT_ERR_EVAL_FALSE) if stack.empty? || !cast_to_bool(stack.last)

    # P2SH witness program
    if flag?(SCRIPT_VERIFY_WITNESS) && redeem_script.witness_program?
      had_witness = true
      # The scriptSig must be _exactly_ a single push of the redeemScript. Otherwise we reintroduce malleability.
      return set_error(SCRIPT_ERR_WITNESS_MALLEATED_P2SH) unless script_sig == (Bitcoin::Script.new << redeem_script.to_hex)

      version, program = redeem_script.witness_data
      return false unless verify_witness_program(witness, version, program, true)
    end
  end

  # The CLEANSTACK check is only performed after potential P2SH evaluation,
  # as the non-P2SH evaluation of a P2SH script will obviously not result in a clean stack (the P2SH inputs remain).
  # The same holds for witness evaluation.
  if flag?(SCRIPT_VERIFY_CLEANSTACK)
    # Disallow CLEANSTACK without P2SH, as otherwise a switch CLEANSTACK->P2SH+CLEANSTACK would be possible,
    # which is not a softfork (and P2SH should be one).
    raise 'assert' unless flag?(SCRIPT_VERIFY_P2SH)
    return set_error(SCRIPT_ERR_CLEANSTACK) unless stack.size == 1
  end

  if flag?(SCRIPT_VERIFY_WITNESS)
    raise 'assert' unless flag?(SCRIPT_VERIFY_P2SH)
    return set_error(SCRIPT_ERR_WITNESS_UNEXPECTED) if !had_witness && !witness.empty?
  end

  true
end

#verify_witness_program(witness, version, program, is_p2sh) ⇒ Object 



106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
 
# File 'lib/bitcoin/script/script_interpreter.rb', line 106

def verify_witness_program(witness, version, program, is_p2sh)
  @stack = witness.stack.map(&:bth)
  need_evaluate = false
  sig_version = nil
  opts = {}
  if version == 0
    need_evaluate = true
    sig_version = :witness_v0
    if program.bytesize == WITNESS_V0_SCRIPTHASH_SIZE # BIP141 P2WSH: 32-byte witness v0 program (which encodes SHA256(script))
      return set_error(SCRIPT_ERR_WITNESS_PROGRAM_WITNESS_EMPTY) if stack.size == 0
      script_pubkey = Bitcoin::Script.parse_from_payload(stack.pop.htb)
      script_hash = Bitcoin.sha256(script_pubkey.to_payload)
      return set_error(SCRIPT_ERR_WITNESS_PROGRAM_MISMATCH) unless script_hash == program
    elsif program.bytesize == WITNESS_V0_KEYHASH_SIZE # BIP141 P2WPKH: 20-byte witness v0 program (which encodes Hash160(pubkey))
      return set_error(SCRIPT_ERR_WITNESS_PROGRAM_MISMATCH) unless stack.size == 2
      script_pubkey = Bitcoin::Script.to_p2pkh(program.bth)
    else
      return set_error(SCRIPT_ERR_WITNESS_PROGRAM_WRONG_LENGTH)
    end
  elsif version == 1 && program.bytesize == WITNESS_V1_TAPROOT_SIZE && !is_p2sh
    # BIP341 Taproot: 32-byte non-P2SH witness v1 program (which encodes a P2C-tweaked pubkey)
    return true unless flag?(SCRIPT_VERIFY_TAPROOT)
    if stack.size == 0
      return set_error(SCRIPT_ERR_WITNESS_PROGRAM_WITNESS_EMPTY)
    elsif stack.size >= 2 && !stack.last.empty? && stack.last[0..1].to_i(16) == ANNEX_TAG
      opts[:annex] = stack.pop.htb
    end
    if stack.size == 1 # Key path spending (stack size is 1 after removing optional annex)
      result = checker.check_schnorr_sig(stack.last, program.bth, :taproot, opts)
      return checker.has_error? ? set_error(checker.error_code) : result
    else
      sig_version = :tapscript
      # Script path spending (stack size is >1 after removing optional annex)
      begin
      control = Bitcoin::Taproot::ControlBlock.parse_from_payload(stack.pop.htb)
      rescue Bitcoin::Taproot::Error
        return set_error(SCRIPT_ERR_TAPROOT_WRONG_CONTROL_SIZE)
      end
      script_payload = stack.pop.htb
      opts[:leaf_hash] = Bitcoin.tagged_hash('TapLeaf', [control.leaf_ver].pack('C') + Bitcoin.pack_var_string(script_payload))
      return set_error(SCRIPT_ERR_WITNESS_PROGRAM_MISMATCH) unless valid_taproot_commitment?(control, program, opts[:leaf_hash])
      if control.leaf_ver == TAPROOT_LEAF_TAPSCRIPT
        opts[:weight_left] = witness.to_payload.bytesize + VALIDATION_WEIGHT_OFFSET
        script_pubkey = Bitcoin::Script.parse_from_payload(script_payload)
        script_pubkey.chunks.each do |c|
          next if c.empty?
          # Note how this condition would not be reached if an unknown OP_SUCCESSx was found
          if c.pushdata?
            return set_error(SCRIPT_ERR_BAD_OPCODE) unless c.valid_pushdata_length?
          elsif Opcodes.op_success?(c.ord)
            # OP_SUCCESSx processing overrides everything, including stack element size limits
            return set_error(SCRIPT_ERR_DISCOURAGE_OP_SUCCESS) if flag?(SCRIPT_VERIFY_DISCOURAGE_OP_SUCCESS)
            return true
          else
            return set_error(SCRIPT_ERR_BAD_OPCODE) unless Opcodes.defined?(c.ord, true)
          end
        end
        return set_error(SCRIPT_ERR_STACK_SIZE) if stack.size > MAX_STACK_SIZE
        need_evaluate = true
      elsif flag?(SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_TAPROOT_VERSION)
        return set_error(SCRIPT_ERR_DISCOURAGE_UPGRADABLE_TAPROOT_VERSION)
      end
      return true unless need_evaluate
    end
  elsif flag?(SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_WITNESS_PROGRAM)
    return set_error(SCRIPT_ERR_DISCOURAGE_UPGRADABLE_WITNESS_PROGRAM)
  else
    return true # Higher version witness scripts return true for future softfork compatibility
  end

  stack.each do |s| # Disallow stack item size > MAX_SCRIPT_ELEMENT_SIZE in witness stack
    return set_error(SCRIPT_ERR_PUSH_SIZE) if s.htb.bytesize > MAX_SCRIPT_ELEMENT_SIZE
  end

  return false unless eval_script(script_pubkey, sig_version, opts: opts)

  return set_error(SCRIPT_ERR_CLEANSTACK) unless stack.size == 1
  return set_error(SCRIPT_ERR_EVAL_FALSE) unless cast_to_bool(stack.last)
  true
end