1 // Copyright (c) 2009-2010 Satoshi Nakamoto
2 // Copyright (c) 2009-2018 The Bitcoin Core developers
3 // Distributed under the MIT software license, see the accompanying
4 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
5
6 #ifndef BITCOIN_SCRIPT_SCRIPT_H
7 #define BITCOIN_SCRIPT_SCRIPT_H
8
9 #include <crypto/common.h>
10 #include <prevector.h>
11 #include <serialize.h>
12
13 #include <assert.h>
14 #include <climits>
15 #include <limits>
16 #include <stdexcept>
17 #include <stdint.h>
18 #include <string.h>
19 #include <string>
20 #include <vector>
21
22 // Maximum number of bytes pushable to the stack
23 static const unsigned int MAX_SCRIPT_ELEMENT_SIZE = 520;
24
25 // Maximum number of non-push operations per script
26 static const int MAX_OPS_PER_SCRIPT = 201;
27
28 // Maximum number of public keys per multisig
29 static const int MAX_PUBKEYS_PER_MULTISIG = 20;
30
31 // Maximum script length in bytes
32 static const int MAX_SCRIPT_SIZE = 10000;
33
34 // Maximum number of values on script interpreter stack
35 static const int MAX_STACK_SIZE = 1000;
36
37 // Threshold for nLockTime: below this value it is interpreted as block number,
38 // otherwise as UNIX timestamp.
39 static const unsigned int LOCKTIME_THRESHOLD = 500000000; // Tue Nov 5 00:53:20 1985 UTC
40
41 // Maximum nLockTime. Since a lock time indicates the last invalid timestamp, a
42 // transaction with this lock time will never be valid unless lock time
43 // checking is disabled (by setting all input sequence numbers to
44 // SEQUENCE_FINAL).
45 static const uint32_t LOCKTIME_MAX = 0xFFFFFFFFU;
46
47 template <typename T>
ToByteVector(const T & in)48 std::vector<unsigned char> ToByteVector(const T& in)
49 {
50 return std::vector<unsigned char>(in.begin(), in.end());
51 }
52
53 /** Script opcodes */
54 enum opcodetype
55 {
56 // push value
57 OP_0 = 0x00,
58 OP_FALSE = OP_0,
59 OP_PUSHDATA1 = 0x4c,
60 OP_PUSHDATA2 = 0x4d,
61 OP_PUSHDATA4 = 0x4e,
62 OP_1NEGATE = 0x4f,
63 OP_RESERVED = 0x50,
64 OP_1 = 0x51,
65 OP_TRUE=OP_1,
66 OP_2 = 0x52,
67 OP_3 = 0x53,
68 OP_4 = 0x54,
69 OP_5 = 0x55,
70 OP_6 = 0x56,
71 OP_7 = 0x57,
72 OP_8 = 0x58,
73 OP_9 = 0x59,
74 OP_10 = 0x5a,
75 OP_11 = 0x5b,
76 OP_12 = 0x5c,
77 OP_13 = 0x5d,
78 OP_14 = 0x5e,
79 OP_15 = 0x5f,
80 OP_16 = 0x60,
81
82 // control
83 OP_NOP = 0x61,
84 OP_VER = 0x62,
85 OP_IF = 0x63,
86 OP_NOTIF = 0x64,
87 OP_VERIF = 0x65,
88 OP_VERNOTIF = 0x66,
89 OP_ELSE = 0x67,
90 OP_ENDIF = 0x68,
91 OP_VERIFY = 0x69,
92 OP_RETURN = 0x6a,
93
94 // stack ops
95 OP_TOALTSTACK = 0x6b,
96 OP_FROMALTSTACK = 0x6c,
97 OP_2DROP = 0x6d,
98 OP_2DUP = 0x6e,
99 OP_3DUP = 0x6f,
100 OP_2OVER = 0x70,
101 OP_2ROT = 0x71,
102 OP_2SWAP = 0x72,
103 OP_IFDUP = 0x73,
104 OP_DEPTH = 0x74,
105 OP_DROP = 0x75,
106 OP_DUP = 0x76,
107 OP_NIP = 0x77,
108 OP_OVER = 0x78,
109 OP_PICK = 0x79,
110 OP_ROLL = 0x7a,
111 OP_ROT = 0x7b,
112 OP_SWAP = 0x7c,
113 OP_TUCK = 0x7d,
114
115 // splice ops
116 OP_CAT = 0x7e,
117 OP_SUBSTR = 0x7f,
118 OP_LEFT = 0x80,
119 OP_RIGHT = 0x81,
120 OP_SIZE = 0x82,
121
122 // bit logic
123 OP_INVERT = 0x83,
124 OP_AND = 0x84,
125 OP_OR = 0x85,
126 OP_XOR = 0x86,
127 OP_EQUAL = 0x87,
128 OP_EQUALVERIFY = 0x88,
129 OP_RESERVED1 = 0x89,
130 OP_RESERVED2 = 0x8a,
131
132 // numeric
133 OP_1ADD = 0x8b,
134 OP_1SUB = 0x8c,
135 OP_2MUL = 0x8d,
136 OP_2DIV = 0x8e,
137 OP_NEGATE = 0x8f,
138 OP_ABS = 0x90,
139 OP_NOT = 0x91,
140 OP_0NOTEQUAL = 0x92,
141
142 OP_ADD = 0x93,
143 OP_SUB = 0x94,
144 OP_MUL = 0x95,
145 OP_DIV = 0x96,
146 OP_MOD = 0x97,
147 OP_LSHIFT = 0x98,
148 OP_RSHIFT = 0x99,
149
150 OP_BOOLAND = 0x9a,
151 OP_BOOLOR = 0x9b,
152 OP_NUMEQUAL = 0x9c,
153 OP_NUMEQUALVERIFY = 0x9d,
154 OP_NUMNOTEQUAL = 0x9e,
155 OP_LESSTHAN = 0x9f,
156 OP_GREATERTHAN = 0xa0,
157 OP_LESSTHANOREQUAL = 0xa1,
158 OP_GREATERTHANOREQUAL = 0xa2,
159 OP_MIN = 0xa3,
160 OP_MAX = 0xa4,
161
162 OP_WITHIN = 0xa5,
163
164 // crypto
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
176 // expansion
177 OP_NOP1 = 0xb0,
178 OP_CHECKLOCKTIMEVERIFY = 0xb1,
179 OP_NOP2 = OP_CHECKLOCKTIMEVERIFY,
180 OP_CHECKSEQUENCEVERIFY = 0xb2,
181 OP_NOP3 = OP_CHECKSEQUENCEVERIFY,
182 OP_NOP4 = 0xb3,
183 OP_NOP5 = 0xb4,
184 OP_NOP6 = 0xb5,
185 OP_NOP7 = 0xb6,
186 OP_NOP8 = 0xb7,
187 OP_NOP9 = 0xb8,
188 OP_NOP10 = 0xb9,
189
190 OP_INVALIDOPCODE = 0xff,
191 };
192
193 // Maximum value that an opcode can be
194 static const unsigned int MAX_OPCODE = OP_NOP10;
195
196 const char* GetOpName(opcodetype opcode);
197
198 class scriptnum_error : public std::runtime_error
199 {
200 public:
scriptnum_error(const std::string & str)201 explicit scriptnum_error(const std::string& str) : std::runtime_error(str) {}
202 };
203
204 class CScriptNum
205 {
206 /**
207 * Numeric opcodes (OP_1ADD, etc) are restricted to operating on 4-byte integers.
208 * The semantics are subtle, though: operands must be in the range [-2^31 +1...2^31 -1],
209 * but results may overflow (and are valid as long as they are not used in a subsequent
210 * numeric operation). CScriptNum enforces those semantics by storing results as
211 * an int64 and allowing out-of-range values to be returned as a vector of bytes but
212 * throwing an exception if arithmetic is done or the result is interpreted as an integer.
213 */
214 public:
215
CScriptNum(const int64_t & n)216 explicit CScriptNum(const int64_t& n)
217 {
218 m_value = n;
219 }
220
221 static const size_t nDefaultMaxNumSize = 4;
222
223 explicit CScriptNum(const std::vector<unsigned char>& vch, bool fRequireMinimal,
224 const size_t nMaxNumSize = nDefaultMaxNumSize)
225 {
226 if (vch.size() > nMaxNumSize) {
227 throw scriptnum_error("script number overflow");
228 }
229 if (fRequireMinimal && vch.size() > 0) {
230 // Check that the number is encoded with the minimum possible
231 // number of bytes.
232 //
233 // If the most-significant-byte - excluding the sign bit - is zero
234 // then we're not minimal. Note how this test also rejects the
235 // negative-zero encoding, 0x80.
236 if ((vch.back() & 0x7f) == 0) {
237 // One exception: if there's more than one byte and the most
238 // significant bit of the second-most-significant-byte is set
239 // it would conflict with the sign bit. An example of this case
240 // is +-255, which encode to 0xff00 and 0xff80 respectively.
241 // (big-endian).
242 if (vch.size() <= 1 || (vch[vch.size() - 2] & 0x80) == 0) {
243 throw scriptnum_error("non-minimally encoded script number");
244 }
245 }
246 }
247 m_value = set_vch(vch);
248 }
249
250 inline bool operator==(const int64_t& rhs) const { return m_value == rhs; }
251 inline bool operator!=(const int64_t& rhs) const { return m_value != rhs; }
252 inline bool operator<=(const int64_t& rhs) const { return m_value <= rhs; }
253 inline bool operator< (const int64_t& rhs) const { return m_value < rhs; }
254 inline bool operator>=(const int64_t& rhs) const { return m_value >= rhs; }
255 inline bool operator> (const int64_t& rhs) const { return m_value > rhs; }
256
257 inline bool operator==(const CScriptNum& rhs) const { return operator==(rhs.m_value); }
258 inline bool operator!=(const CScriptNum& rhs) const { return operator!=(rhs.m_value); }
259 inline bool operator<=(const CScriptNum& rhs) const { return operator<=(rhs.m_value); }
260 inline bool operator< (const CScriptNum& rhs) const { return operator< (rhs.m_value); }
261 inline bool operator>=(const CScriptNum& rhs) const { return operator>=(rhs.m_value); }
262 inline bool operator> (const CScriptNum& rhs) const { return operator> (rhs.m_value); }
263
264 inline CScriptNum operator+( const int64_t& rhs) const { return CScriptNum(m_value + rhs);}
265 inline CScriptNum operator-( const int64_t& rhs) const { return CScriptNum(m_value - rhs);}
266 inline CScriptNum operator+( const CScriptNum& rhs) const { return operator+(rhs.m_value); }
267 inline CScriptNum operator-( const CScriptNum& rhs) const { return operator-(rhs.m_value); }
268
269 inline CScriptNum& operator+=( const CScriptNum& rhs) { return operator+=(rhs.m_value); }
270 inline CScriptNum& operator-=( const CScriptNum& rhs) { return operator-=(rhs.m_value); }
271
272 inline CScriptNum operator&( const int64_t& rhs) const { return CScriptNum(m_value & rhs);}
273 inline CScriptNum operator&( const CScriptNum& rhs) const { return operator&(rhs.m_value); }
274
275 inline CScriptNum& operator&=( const CScriptNum& rhs) { return operator&=(rhs.m_value); }
276
277 inline CScriptNum operator-() const
278 {
279 assert(m_value != std::numeric_limits<int64_t>::min());
280 return CScriptNum(-m_value);
281 }
282
283 inline CScriptNum& operator=( const int64_t& rhs)
284 {
285 m_value = rhs;
286 return *this;
287 }
288
289 inline CScriptNum& operator+=( const int64_t& rhs)
290 {
291 assert(rhs == 0 || (rhs > 0 && m_value <= std::numeric_limits<int64_t>::max() - rhs) ||
292 (rhs < 0 && m_value >= std::numeric_limits<int64_t>::min() - rhs));
293 m_value += rhs;
294 return *this;
295 }
296
297 inline CScriptNum& operator-=( const int64_t& rhs)
298 {
299 assert(rhs == 0 || (rhs > 0 && m_value >= std::numeric_limits<int64_t>::min() + rhs) ||
300 (rhs < 0 && m_value <= std::numeric_limits<int64_t>::max() + rhs));
301 m_value -= rhs;
302 return *this;
303 }
304
305 inline CScriptNum& operator&=( const int64_t& rhs)
306 {
307 m_value &= rhs;
308 return *this;
309 }
310
getint()311 int getint() const
312 {
313 if (m_value > std::numeric_limits<int>::max())
314 return std::numeric_limits<int>::max();
315 else if (m_value < std::numeric_limits<int>::min())
316 return std::numeric_limits<int>::min();
317 return m_value;
318 }
319
getvch()320 std::vector<unsigned char> getvch() const
321 {
322 return serialize(m_value);
323 }
324
serialize(const int64_t & value)325 static std::vector<unsigned char> serialize(const int64_t& value)
326 {
327 if(value == 0)
328 return std::vector<unsigned char>();
329
330 std::vector<unsigned char> result;
331 const bool neg = value < 0;
332 uint64_t absvalue = neg ? -value : value;
333
334 while(absvalue)
335 {
336 result.push_back(absvalue & 0xff);
337 absvalue >>= 8;
338 }
339
340 // - If the most significant byte is >= 0x80 and the value is positive, push a
341 // new zero-byte to make the significant byte < 0x80 again.
342
343 // - If the most significant byte is >= 0x80 and the value is negative, push a
344 // new 0x80 byte that will be popped off when converting to an integral.
345
346 // - If the most significant byte is < 0x80 and the value is negative, add
347 // 0x80 to it, since it will be subtracted and interpreted as a negative when
348 // converting to an integral.
349
350 if (result.back() & 0x80)
351 result.push_back(neg ? 0x80 : 0);
352 else if (neg)
353 result.back() |= 0x80;
354
355 return result;
356 }
357
358 private:
set_vch(const std::vector<unsigned char> & vch)359 static int64_t set_vch(const std::vector<unsigned char>& vch)
360 {
361 if (vch.empty())
362 return 0;
363
364 int64_t result = 0;
365 for (size_t i = 0; i != vch.size(); ++i)
366 result |= static_cast<int64_t>(vch[i]) << 8*i;
367
368 // If the input vector's most significant byte is 0x80, remove it from
369 // the result's msb and return a negative.
370 if (vch.back() & 0x80)
371 return -((int64_t)(result & ~(0x80ULL << (8 * (vch.size() - 1)))));
372
373 return result;
374 }
375
376 int64_t m_value;
377 };
378
379 /**
380 * We use a prevector for the script to reduce the considerable memory overhead
381 * of vectors in cases where they normally contain a small number of small elements.
382 * Tests in October 2015 showed use of this reduced dbcache memory usage by 23%
383 * and made an initial sync 13% faster.
384 */
385 typedef prevector<28, unsigned char> CScriptBase;
386
387 bool GetScriptOp(CScriptBase::const_iterator& pc, CScriptBase::const_iterator end, opcodetype& opcodeRet, std::vector<unsigned char>* pvchRet);
388
389 /** Serialized script, used inside transaction inputs and outputs */
390 class CScript : public CScriptBase
391 {
392 protected:
push_int64(int64_t n)393 CScript& push_int64(int64_t n)
394 {
395 if (n == -1 || (n >= 1 && n <= 16))
396 {
397 push_back(n + (OP_1 - 1));
398 }
399 else if (n == 0)
400 {
401 push_back(OP_0);
402 }
403 else
404 {
405 *this << CScriptNum::serialize(n);
406 }
407 return *this;
408 }
409 public:
CScript()410 CScript() { }
CScript(const_iterator pbegin,const_iterator pend)411 CScript(const_iterator pbegin, const_iterator pend) : CScriptBase(pbegin, pend) { }
CScript(std::vector<unsigned char>::const_iterator pbegin,std::vector<unsigned char>::const_iterator pend)412 CScript(std::vector<unsigned char>::const_iterator pbegin, std::vector<unsigned char>::const_iterator pend) : CScriptBase(pbegin, pend) { }
CScript(const unsigned char * pbegin,const unsigned char * pend)413 CScript(const unsigned char* pbegin, const unsigned char* pend) : CScriptBase(pbegin, pend) { }
414
415 ADD_SERIALIZE_METHODS;
416
417 template <typename Stream, typename Operation>
SerializationOp(Stream & s,Operation ser_action)418 inline void SerializationOp(Stream& s, Operation ser_action) {
419 READWRITEAS(CScriptBase, *this);
420 }
421
422 CScript& operator+=(const CScript& b)
423 {
424 reserve(size() + b.size());
425 insert(end(), b.begin(), b.end());
426 return *this;
427 }
428
429 friend CScript operator+(const CScript& a, const CScript& b)
430 {
431 CScript ret = a;
432 ret += b;
433 return ret;
434 }
435
CScript(int64_t b)436 CScript(int64_t b) { operator<<(b); }
437
CScript(opcodetype b)438 explicit CScript(opcodetype b) { operator<<(b); }
CScript(const CScriptNum & b)439 explicit CScript(const CScriptNum& b) { operator<<(b); }
CScript(const std::vector<unsigned char> & b)440 explicit CScript(const std::vector<unsigned char>& b) { operator<<(b); }
441
442
443 CScript& operator<<(int64_t b) { return push_int64(b); }
444
445 CScript& operator<<(opcodetype opcode)
446 {
447 if (opcode < 0 || opcode > 0xff)
448 throw std::runtime_error("CScript::operator<<(): invalid opcode");
449 insert(end(), (unsigned char)opcode);
450 return *this;
451 }
452
453 CScript& operator<<(const CScriptNum& b)
454 {
455 *this << b.getvch();
456 return *this;
457 }
458
459 CScript& operator<<(const std::vector<unsigned char>& b)
460 {
461 if (b.size() < OP_PUSHDATA1)
462 {
463 insert(end(), (unsigned char)b.size());
464 }
465 else if (b.size() <= 0xff)
466 {
467 insert(end(), OP_PUSHDATA1);
468 insert(end(), (unsigned char)b.size());
469 }
470 else if (b.size() <= 0xffff)
471 {
472 insert(end(), OP_PUSHDATA2);
473 uint8_t _data[2];
474 WriteLE16(_data, b.size());
475 insert(end(), _data, _data + sizeof(_data));
476 }
477 else
478 {
479 insert(end(), OP_PUSHDATA4);
480 uint8_t _data[4];
481 WriteLE32(_data, b.size());
482 insert(end(), _data, _data + sizeof(_data));
483 }
484 insert(end(), b.begin(), b.end());
485 return *this;
486 }
487
488 CScript& operator<<(const CScript& b)
489 {
490 // I'm not sure if this should push the script or concatenate scripts.
491 // If there's ever a use for pushing a script onto a script, delete this member fn
492 assert(!"Warning: Pushing a CScript onto a CScript with << is probably not intended, use + to concatenate!");
493 return *this;
494 }
495
496
GetOp(const_iterator & pc,opcodetype & opcodeRet,std::vector<unsigned char> & vchRet)497 bool GetOp(const_iterator& pc, opcodetype& opcodeRet, std::vector<unsigned char>& vchRet) const
498 {
499 return GetScriptOp(pc, end(), opcodeRet, &vchRet);
500 }
501
GetOp(const_iterator & pc,opcodetype & opcodeRet)502 bool GetOp(const_iterator& pc, opcodetype& opcodeRet) const
503 {
504 return GetScriptOp(pc, end(), opcodeRet, nullptr);
505 }
506
507
508 /** Encode/decode small integers: */
DecodeOP_N(opcodetype opcode)509 static int DecodeOP_N(opcodetype opcode)
510 {
511 if (opcode == OP_0)
512 return 0;
513 assert(opcode >= OP_1 && opcode <= OP_16);
514 return (int)opcode - (int)(OP_1 - 1);
515 }
EncodeOP_N(int n)516 static opcodetype EncodeOP_N(int n)
517 {
518 assert(n >= 0 && n <= 16);
519 if (n == 0)
520 return OP_0;
521 return (opcodetype)(OP_1+n-1);
522 }
523
524 /**
525 * Pre-version-0.6, Bitcoin always counted CHECKMULTISIGs
526 * as 20 sigops. With pay-to-script-hash, that changed:
527 * CHECKMULTISIGs serialized in scriptSigs are
528 * counted more accurately, assuming they are of the form
529 * ... OP_N CHECKMULTISIG ...
530 */
531 unsigned int GetSigOpCount(bool fAccurate) const;
532
533 /**
534 * Accurately count sigOps, including sigOps in
535 * pay-to-script-hash transactions:
536 */
537 unsigned int GetSigOpCount(const CScript& scriptSig) const;
538
539 bool IsPayToScriptHash() const;
540 bool IsPayToWitnessScriptHash() const;
541 bool IsWitnessProgram(int& version, std::vector<unsigned char>& program) const;
542
543 /** Called by IsStandardTx and P2SH/BIP62 VerifyScript (which makes it consensus-critical). */
544 bool IsPushOnly(const_iterator pc) const;
545 bool IsPushOnly() const;
546
547 /** Check if the script contains valid OP_CODES */
548 bool HasValidOps() const;
549
550 /**
551 * Returns whether the script is guaranteed to fail at execution,
552 * regardless of the initial stack. This allows outputs to be pruned
553 * instantly when entering the UTXO set.
554 */
IsUnspendable()555 bool IsUnspendable() const
556 {
557 return (size() > 0 && *begin() == OP_RETURN) || (size() > MAX_SCRIPT_SIZE);
558 }
559
clear()560 void clear()
561 {
562 // The default prevector::clear() does not release memory
563 CScriptBase::clear();
564 shrink_to_fit();
565 }
566 };
567
568 struct CScriptWitness
569 {
570 // Note that this encodes the data elements being pushed, rather than
571 // encoding them as a CScript that pushes them.
572 std::vector<std::vector<unsigned char> > stack;
573
574 // Some compilers complain without a default constructor
CScriptWitnessCScriptWitness575 CScriptWitness() { }
576
IsNullCScriptWitness577 bool IsNull() const { return stack.empty(); }
578
SetNullCScriptWitness579 void SetNull() { stack.clear(); stack.shrink_to_fit(); }
580
581 std::string ToString() const;
582 };
583
584 class CReserveScript
585 {
586 public:
587 CScript reserveScript;
KeepScript()588 virtual void KeepScript() {}
CReserveScript()589 CReserveScript() {}
~CReserveScript()590 virtual ~CReserveScript() {}
591 };
592
593 #endif // BITCOIN_SCRIPT_SCRIPT_H
594