lib: Add Taproot support to libconsensus #21158

  12 | @@ -13,13 +13,13 @@
  13 |  namespace {
  14 |  
  15 |  /** A class that deserializes a single CTransaction one time. */
  16 | -class TxInputStream
  17 | +class InputStream

---

 107 |      } catch (const std::exception&) {
 108 |          return set_error(err, bitcoinconsensus_ERR_TX_DESERIALIZE); // Error deserializing
 109 |      }
 110 |  }
 111 |  
 112 | +int bitcoinconsensus_verify_script_with_spent_outputs(const unsigned char *scriptPubKey, unsigned int scriptPubKeyLen, int64_t amount,

---

  87 |          CTransaction tx(deserialize, stream);
  88 | +        std::vector<CTxOut> spent_outputs;
  89 | +        if (spentOutputs != nullptr) {
  90 | +            InputStream spent_outputs_stream(PROTOCOL_VERSION, spentOutputs, spentOutputsLen);
  91 | +            spent_outputs_stream >> spent_outputs;
  92 | +        }

---

  15 | +`bitcoinconsensus_version` returns an `unsigned int` with the API version *(currently `2`)*.
  16 |  
  17 |  #### Script Validation
  18 |  
  19 | -`bitcoinconsensus_verify_script` returns an `int` with the status of the verification. It will be `1` if the input script correctly spends the previous output `scriptPubKey`.
  20 | +`bitcoinconsensus_verify_script`, `bitcoinconsensus_verify_script_with_amounts` and `bitcoinconsensus_verify_script_with_spent_outputs` return an `int` with the status of the verification. It will be `1` if the input script correctly spends the previous output `scriptPubKey`.

---

  26 | @@ -26,6 +27,28 @@ The interface is defined in the C header `bitcoinconsensus.h` located in `src/sc
  27 |  - `unsigned int flags` - The script validation flags *(see below)*.
  28 |  - `bitcoinconsensus_error* err` - Will have the error/success code for the operation *(see below)*.
  29 |  
  30 | +###### bitcoinconsensus_verify_script_with_amounts

---

  65 | @@ -42,6 +66,8 @@ The interface is defined in the C header `bitcoinconsensus.h` located in `src/sc
  66 |  - `bitcoinconsensus_ERR_DESERIALIZE` - An error deserializing `txTo`
  67 |  - `bitcoinconsensus_ERR_AMOUNT_REQUIRED` - Input amount is required if WITNESS is used
  68 |  - `bitcoinconsensus_ERR_INVALID_FLAGS` - Script verification `flags` are invalid (i.e. not part of the libconsensus interface)
  69 | +- `bitcoinconsensus_ERR_SPENT_OUTPUTS_REQUIRED` - Spent outputs are required if TAPROOT is used
  70 | +- `bitcoinconsensus_ERR_SPENT_OUTPUTS_MISMATCH` - Spent outputs size doesn't match tx inputs size
  71 |  
  72 |  ### Example Implementations

---

1758 |          for (const auto flags : ALL_CONSENSUS_FLAGS) {
1759 |              // If a test is supposed to fail with test_flags, it should also fail with any superset thereof.
1760 |              if ((flags & test_flags) == test_flags) {
1761 |                  bool ret = VerifyScript(tx.vin[idx].scriptSig, prevouts[idx].scriptPubKey, &tx.vin[idx].scriptWitness, flags, txcheck, nullptr);
1762 |                  BOOST_CHECK(!ret);
1763 | +                #if defined(HAVE_CONSENSUS_LIB)

---

  54 | @@ -53,9 +55,11 @@ enum
  55 |      bitcoinconsensus_SCRIPT_FLAGS_VERIFY_CHECKLOCKTIMEVERIFY = (1U << 9), // enable CHECKLOCKTIMEVERIFY (BIP65)
  56 |      bitcoinconsensus_SCRIPT_FLAGS_VERIFY_CHECKSEQUENCEVERIFY = (1U << 10), // enable CHECKSEQUENCEVERIFY (BIP112)
  57 |      bitcoinconsensus_SCRIPT_FLAGS_VERIFY_WITNESS             = (1U << 11), // enable WITNESS (BIP141)
  58 | +    bitcoinconsensus_SCRIPT_FLAGS_VERIFY_TAPROOT             = (1U << 17), // enable TAPROOT (BIP341-343)

---

  83 | @@ -83,6 +84,14 @@ static int verify_script(const unsigned char *scriptPubKey, unsigned int scriptP
  84 |      try {
  85 |          TxInputStream stream(PROTOCOL_VERSION, txTo, txToLen);
  86 |          CTransaction tx(deserialize, stream);
  87 | +        std::vector<CTxOut> spent_outputs;
  88 | +        if (spentOutputs != nullptr) {
  89 | +            TxInputStream spent_outputs_stream(PROTOCOL_VERSION, spentOutputs, spentOutputsLen);
  90 | +            spent_outputs_stream >> spent_outputs;

---

  41 | +- `const unsigned char *scriptPubKey` - The previous output script that encumbers spending.
  42 | +- `unsigned int scriptPubKeyLen` - The number of bytes for the `scriptPubKey`.
  43 | +- `int64_t amount` - The amount spent in the input
  44 | +- `const unsigned char *txTo` - The transaction with the input that is spending the previous output.
  45 | +- `unsigned int txToLen` - The number of bytes for the `txTo`.
  46 | +- `const unsigned char *spentOutputs` - Previous outputs spent in the transaction

---