src/primitives/transaction.h

   1 // Copyright (c) 2009-2010 Satoshi Nakamoto
   2 // Copyright (c) 2009-2017 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_PRIMITIVES_TRANSACTION_H
   7 #define BITCOIN_PRIMITIVES_TRANSACTION_H
   8
   9 #include <stdint.h>
  10 #include <amount.h>
  11 #include <script/script.h>
  12 #include <serialize.h>
  13 #include <uint256.h>
  14
  15 static const int SERIALIZE_TRANSACTION_NO_WITNESS = 0x40000000;
  16
  17 /** An outpoint - a combination of a transaction hash and an index n into its vout */
  18 class COutPoint
  19 {
  20 public:
  21     uint256 hash;
  22     uint32_t n;
  23
  24     COutPoint(): n((uint32_t) -1) { }
  25     COutPoint(const uint256& hashIn, uint32_t nIn): hash(hashIn), n(nIn) { }
  26
  27     ADD_SERIALIZE_METHODS;
  28
  29     template <typename Stream, typename Operation>
  30     inline void SerializationOp(Stream& s, Operation ser_action) {
  31         READWRITE(hash);
  32         READWRITE(n);
  33     }
  34
  35     void SetNull() { hash.SetNull(); n = (uint32_t) -1; }
  36     bool IsNull() const { return (hash.IsNull() && n == (uint32_t) -1); }
  37
  38     friend bool operator<(const COutPoint& a, const COutPoint& b)
  39     {
  40         int cmp = a.hash.Compare(b.hash);
  41         return cmp < 0 || (cmp == 0 && a.n < b.n);
  42     }
  43
  44     friend bool operator==(const COutPoint& a, const COutPoint& b)
  45     {
  46         return (a.hash == b.hash && a.n == b.n);
  47     }
  48
  49     friend bool operator!=(const COutPoint& a, const COutPoint& b)
  50     {
  51         return !(a == b);
  52     }
  53
  54     std::string ToString() const;
  55 };
  56
  57 /** An input of a transaction.  It contains the location of the previous
  58  * transaction's output that it claims and a signature that matches the
  59  * output's public key.
  60  */
  61 class CTxIn
  62 {
  63 public:
  64     COutPoint prevout;
  65     CScript scriptSig;
  66     uint32_t nSequence;
  67     CScriptWitness scriptWitness; //! Only serialized through CTransaction
  68
  69     /* Setting nSequence to this value for every input in a transaction
  70      * disables nLockTime. */
  71     static const uint32_t SEQUENCE_FINAL = 0xffffffff;
  72
  73     /* Below flags apply in the context of BIP 68*/
  74     /* If this flag set, CTxIn::nSequence is NOT interpreted as a
  75      * relative lock-time. */
  76     static const uint32_t SEQUENCE_LOCKTIME_DISABLE_FLAG = (1 << 31);
  77
  78     /* If CTxIn::nSequence encodes a relative lock-time and this flag
  79      * is set, the relative lock-time has units of 512 seconds,
  80      * otherwise it specifies blocks with a granularity of 1. */
  81     static const uint32_t SEQUENCE_LOCKTIME_TYPE_FLAG = (1 << 22);
  82
  83     /* If CTxIn::nSequence encodes a relative lock-time, this mask is
  84      * applied to extract that lock-time from the sequence field. */
  85     static const uint32_t SEQUENCE_LOCKTIME_MASK = 0x0000ffff;
  86
  87     /* In order to use the same number of bits to encode roughly the
  88      * same wall-clock duration, and because blocks are naturally
  89      * limited to occur every 600s on average, the minimum granularity
  90      * for time-based relative lock-time is fixed at 512 seconds.
  91      * Converting from CTxIn::nSequence to seconds is performed by
  92      * multiplying by 512 = 2^9, or equivalently shifting up by
  93      * 9 bits. */
  94     static const int SEQUENCE_LOCKTIME_GRANULARITY = 9;
  95
  96     CTxIn()
  97     {
  98         nSequence = SEQUENCE_FINAL;
  99     }
 100
 101     explicit CTxIn(COutPoint prevoutIn, CScript scriptSigIn=CScript(), uint32_t nSequenceIn=SEQUENCE_FINAL);
 102     CTxIn(uint256 hashPrevTx, uint32_t nOut, CScript scriptSigIn=CScript(), uint32_t nSequenceIn=SEQUENCE_FINAL);
 103
 104     ADD_SERIALIZE_METHODS;
 105
 106     template <typename Stream, typename Operation>
 107     inline void SerializationOp(Stream& s, Operation ser_action) {
 108         READWRITE(prevout);
 109         READWRITE(scriptSig);
 110         READWRITE(nSequence);
 111     }
 112
 113     friend bool operator==(const CTxIn& a, const CTxIn& b)
 114     {
 115         return (a.prevout   == b.prevout &&
 116                 a.scriptSig == b.scriptSig &&
 117                 a.nSequence == b.nSequence);
 118     }
 119
 120     friend bool operator!=(const CTxIn& a, const CTxIn& b)
 121     {
 122         return !(a == b);
 123     }
 124
 125     std::string ToString() const;
 126 };
 127
 128 /** An output of a transaction.  It contains the public key that the next input
 129  * must be able to sign with to claim it.
 130  */
 131 class CTxOut
 132 {
 133 public:
 134     CAmount nValue;
 135     CScript scriptPubKey;
 136
 137     CTxOut()
 138     {
 139         SetNull();
 140     }
 141
 142     CTxOut(const CAmount& nValueIn, CScript scriptPubKeyIn);
 143
 144     ADD_SERIALIZE_METHODS;
 145
 146     template <typename Stream, typename Operation>
 147     inline void SerializationOp(Stream& s, Operation ser_action) {
 148         READWRITE(nValue);
 149         READWRITE(scriptPubKey);
 150     }
 151
 152     void SetNull()
 153     {
 154         nValue = -1;
 155         scriptPubKey.clear();
 156     }
 157
 158     bool IsNull() const
 159     {
 160         return (nValue == -1);
 161     }
 162
 163     friend bool operator==(const CTxOut& a, const CTxOut& b)
 164     {
 165         return (a.nValue       == b.nValue &&
 166                 a.scriptPubKey == b.scriptPubKey);
 167     }
 168
 169     friend bool operator!=(const CTxOut& a, const CTxOut& b)
 170     {
 171         return !(a == b);
 172     }
 173
 174     std::string ToString() const;
 175 };
 176
 177 struct CMutableTransaction;
 178
 179 /**
 180  * Basic transaction serialization format:
 181  * - int32_t nVersion
 182  * - std::vector<CTxIn> vin
 183  * - std::vector<CTxOut> vout
 184  * - uint32_t nLockTime
 185  *
 186  * Extended transaction serialization format:
 187  * - int32_t nVersion
 188  * - unsigned char dummy = 0x00
 189  * - unsigned char flags (!= 0)
 190  * - std::vector<CTxIn> vin
 191  * - std::vector<CTxOut> vout
 192  * - if (flags & 1):
 193  *   - CTxWitness wit;
 194  * - uint32_t nLockTime
 195  */
 196 template<typename Stream, typename TxType>
 197 inline void UnserializeTransaction(TxType& tx, Stream& s) {
 198     const bool fAllowWitness = !(s.GetVersion() & SERIALIZE_TRANSACTION_NO_WITNESS);
 199
 200     s >> tx.nVersion;
 201     unsigned char flags = 0;
 202     tx.vin.clear();
 203     tx.vout.clear();
 204     /* Try to read the vin. In case the dummy is there, this will be read as an empty vector. */
 205     s >> tx.vin;
 206     if (tx.vin.size() == 0 && fAllowWitness) {
 207         /* We read a dummy or an empty vin. */
 208         s >> flags;
 209         if (flags != 0) {
 210             s >> tx.vin;
 211             s >> tx.vout;
 212         }
 213     } else {
 214         /* We read a non-empty vin. Assume a normal vout follows. */
 215         s >> tx.vout;
 216     }
 217     if ((flags & 1) && fAllowWitness) {
 218         /* The witness flag is present, and we support witnesses. */
 219         flags ^= 1;
 220         for (size_t i = 0; i < tx.vin.size(); i++) {
 221             s >> tx.vin[i].scriptWitness.stack;
 222         }
 223     }
 224     if (flags) {
 225         /* Unknown flag in the serialization */
 226         throw std::ios_base::failure("Unknown transaction optional data");
 227     }
 228     s >> tx.nLockTime;
 229 }
 230
 231 template<typename Stream, typename TxType>
 232 inline void SerializeTransaction(const TxType& tx, Stream& s) {
 233     const bool fAllowWitness = !(s.GetVersion() & SERIALIZE_TRANSACTION_NO_WITNESS);
 234
 235     s << tx.nVersion;
 236     unsigned char flags = 0;
 237     // Consistency check
 238     if (fAllowWitness) {
 239         /* Check whether witnesses need to be serialized. */
 240         if (tx.HasWitness()) {
 241             flags |= 1;
 242         }
 243     }
 244     if (flags) {
 245         /* Use extended format in case witnesses are to be serialized. */
 246         std::vector<CTxIn> vinDummy;
 247         s << vinDummy;
 248         s << flags;
 249     }
 250     s << tx.vin;
 251     s << tx.vout;
 252     if (flags & 1) {
 253         for (size_t i = 0; i < tx.vin.size(); i++) {
 254             s << tx.vin[i].scriptWitness.stack;
 255         }
 256     }
 257     s << tx.nLockTime;
 258 }
 259
 260
 261 /** The basic transaction that is broadcasted on the network and contained in
 262  * blocks.  A transaction can contain multiple inputs and outputs.
 263  */
 264 class CTransaction
 265 {
 266 public:
 267     // Default transaction version.
 268     static const int32_t CURRENT_VERSION=2;
 269
 270     // Changing the default transaction version requires a two step process: first
 271     // adapting relay policy by bumping MAX_STANDARD_VERSION, and then later date
 272     // bumping the default CURRENT_VERSION at which point both CURRENT_VERSION and
 273     // MAX_STANDARD_VERSION will be equal.
 274     static const int32_t MAX_STANDARD_VERSION=2;
 275
 276     // The local variables are made const to prevent unintended modification
 277     // without updating the cached hash value. However, CTransaction is not
 278     // actually immutable; deserialization and assignment are implemented,
 279     // and bypass the constness. This is safe, as they update the entire
 280     // structure, including the hash.
 281     const std::vector<CTxIn> vin;
 282     const std::vector<CTxOut> vout;
 283     const int32_t nVersion;
 284     const uint32_t nLockTime;
 285
 286 private:
 287     /** Memory only. */
 288     const uint256 hash;
 289
 290     uint256 ComputeHash() const;
 291
 292 public:
 293     /** Construct a CTransaction that qualifies as IsNull() */
 294     CTransaction();
 295
 296     /** Convert a CMutableTransaction into a CTransaction. */
 297     CTransaction(const CMutableTransaction &tx);
 298     CTransaction(CMutableTransaction &&tx);
 299
 300     template <typename Stream>
 301     inline void Serialize(Stream& s) const {
 302         SerializeTransaction(*this, s);
 303     }
 304
 305     /** This deserializing constructor is provided instead of an Unserialize method.
 306      *  Unserialize is not possible, since it would require overwriting const fields. */
 307     template <typename Stream>
 308     CTransaction(deserialize_type, Stream& s) : CTransaction(CMutableTransaction(deserialize, s)) {}
 309
 310     bool IsNull() const {
 311         return vin.empty() && vout.empty();
 312     }
 313
 314     const uint256& GetHash() const {
 315         return hash;
 316     }
 317
 318     // Compute a hash that includes both transaction and witness data
 319     uint256 GetWitnessHash() const;
 320
 321     // Return sum of txouts.
 322     CAmount GetValueOut() const;
 323     // GetValueIn() is a method on CCoinsViewCache, because
 324     // inputs must be known to compute value in.
 325
 326     /**
 327      * Get the total transaction size in bytes, including witness data.
 328      * "Total Size" defined in BIP141 and BIP144.
 329      * @return Total transaction size in bytes
 330      */
 331     unsigned int GetTotalSize() const;
 332
 333     bool IsCoinBase() const
 334     {
 335         return (vin.size() == 1 && vin[0].prevout.IsNull());
 336     }
 337
 338     friend bool operator==(const CTransaction& a, const CTransaction& b)
 339     {
 340         return a.hash == b.hash;
 341     }
 342
 343     friend bool operator!=(const CTransaction& a, const CTransaction& b)
 344     {
 345         return a.hash != b.hash;
 346     }
 347
 348     std::string ToString() const;
 349
 350     bool HasWitness() const
 351     {
 352         for (size_t i = 0; i < vin.size(); i++) {
 353             if (!vin[i].scriptWitness.IsNull()) {
 354                 return true;
 355             }
 356         }
 357         return false;
 358     }
 359 };
 360
 361 /** A mutable version of CTransaction. */
 362 struct CMutableTransaction
 363 {
 364     std::vector<CTxIn> vin;
 365     std::vector<CTxOut> vout;
 366     int32_t nVersion;
 367     uint32_t nLockTime;
 368
 369     CMutableTransaction();
 370     CMutableTransaction(const CTransaction& tx);
 371
 372     template <typename Stream>
 373     inline void Serialize(Stream& s) const {
 374         SerializeTransaction(*this, s);
 375     }
 376
 377
 378     template <typename Stream>
 379     inline void Unserialize(Stream& s) {
 380         UnserializeTransaction(*this, s);
 381     }
 382
 383     template <typename Stream>
 384     CMutableTransaction(deserialize_type, Stream& s) {
 385         Unserialize(s);
 386     }
 387
 388     /** Compute the hash of this CMutableTransaction. This is computed on the
 389      * fly, as opposed to GetHash() in CTransaction, which uses a cached result.
 390      */
 391     uint256 GetHash() const;
 392
 393     friend bool operator==(const CMutableTransaction& a, const CMutableTransaction& b)
 394     {
 395         return a.GetHash() == b.GetHash();
 396     }
 397
 398     bool HasWitness() const
 399     {
 400         for (size_t i = 0; i < vin.size(); i++) {
 401             if (!vin[i].scriptWitness.IsNull()) {
 402                 return true;
 403             }
 404         }
 405         return false;
 406     }
 407 };
 408
 409 typedef std::shared_ptr<const CTransaction> CTransactionRef;
 410 static inline CTransactionRef MakeTransactionRef() { return std::make_shared<const CTransaction>(); }
 411 template <typename Tx> static inline CTransactionRef MakeTransactionRef(Tx&& txIn) { return std::make_shared<const CTransaction>(std::forward<Tx>(txIn)); }
 412
 413 #endif // BITCOIN_PRIMITIVES_TRANSACTION_H