Add MissingDataBehavior and make TransactionSignatureChecker handle it

This allows specifying how *TransactionSignatureChecker will behave when
presented with missing transaction data such as amounts spent, BIP341 data,
or spent outputs.

As all call sites still (implicitly) use MissingDataBehavior::ASSERT_FAIL,
this commit introduces no change in behavior.

1 files changed, 12 insertions, 2 deletions

diff --git a/src/script/interpreter.h b/src/script/interpreter.h
index b4c163c841..490b337108 100644
--- a/src/script/interpreter.h
+++ b/src/script/interpreter.h
@@ -247,11 +247,21 @@ public:
     virtual ~BaseSignatureChecker() {}
 };
 
+/** Enum to specify what *TransactionSignatureChecker's behavior should be
+ *  when dealing with missing transaction data.
+ */
+enum class MissingDataBehavior
+{
+    ASSERT_FAIL,  //!< Abort execution through assertion failure (for consensus code)
+    FAIL,         //!< Just act as if the signature was invalid
+};
+
 template <class T>
 class GenericTransactionSignatureChecker : public BaseSignatureChecker
 {
 private:
     const T* txTo;
+    const MissingDataBehavior m_mdb;
     unsigned int nIn;
     const CAmount amount;
     const PrecomputedTransactionData* txdata;
@@ -261,8 +271,8 @@ protected:
     virtual bool VerifySchnorrSignature(Span<const unsigned char> sig, const XOnlyPubKey& pubkey, const uint256& sighash) const;
 
 public:
-    GenericTransactionSignatureChecker(const T* txToIn, unsigned int nInIn, const CAmount& amountIn) : txTo(txToIn), nIn(nInIn), amount(amountIn), txdata(nullptr) {}
-    GenericTransactionSignatureChecker(const T* txToIn, unsigned int nInIn, const CAmount& amountIn, const PrecomputedTransactionData& txdataIn) : txTo(txToIn), nIn(nInIn), amount(amountIn), txdata(&txdataIn) {}
+    GenericTransactionSignatureChecker(const T* txToIn, unsigned int nInIn, const CAmount& amountIn, MissingDataBehavior mdb = MissingDataBehavior::ASSERT_FAIL) : txTo(txToIn), m_mdb(mdb), nIn(nInIn), amount(amountIn), txdata(nullptr) {}
+    GenericTransactionSignatureChecker(const T* txToIn, unsigned int nInIn, const CAmount& amountIn, const PrecomputedTransactionData& txdataIn, MissingDataBehavior mdb = MissingDataBehavior::ASSERT_FAIL) : txTo(txToIn), m_mdb(mdb), nIn(nInIn), amount(amountIn), txdata(&txdataIn) {}
     bool CheckECDSASignature(const std::vector<unsigned char>& scriptSig, const std::vector<unsigned char>& vchPubKey, const CScript& scriptCode, SigVersion sigversion) const override;
     bool CheckSchnorrSignature(Span<const unsigned char> sig, Span<const unsigned char> pubkey, SigVersion sigversion, const ScriptExecutionData& execdata, ScriptError* serror = nullptr) const override;
     bool CheckLockTime(const CScriptNum& nLockTime) const override;