Introduce DeferringSignatureChecker and inherit with SignatureExtractor

Introduces a DeferringSignatureChecker which simply takes a
BaseSignatureChecker and passes through everything.
SignatureExtractorChecker now subclasses DeferringSignatureChecker. This
allows for all BaseSignatureChecker functions to be implemented for
SignatureExtractorChecker, while allowing for future signature checkers
which opreate similarly to SignatureExtractorChecker.

2 files changed, 32 insertions, 4 deletions

diff --git a/src/script/interpreter.h b/src/script/interpreter.h
index b4c163c841..effbc055d4 100644
--- a/src/script/interpreter.h
+++ b/src/script/interpreter.h
@@ -272,6 +272,34 @@ public:
 using TransactionSignatureChecker = GenericTransactionSignatureChecker<CTransaction>;
 using MutableTransactionSignatureChecker = GenericTransactionSignatureChecker<CMutableTransaction>;
 
+class DeferringSignatureChecker : public BaseSignatureChecker
+{
+protected:
+    BaseSignatureChecker& m_checker;
+
+public:
+    DeferringSignatureChecker(BaseSignatureChecker& checker) : m_checker(checker) {}
+
+    bool CheckECDSASignature(const std::vector<unsigned char>& scriptSig, const std::vector<unsigned char>& vchPubKey, const CScript& scriptCode, SigVersion sigversion) const override
+    {
+        return m_checker.CheckECDSASignature(scriptSig, vchPubKey, scriptCode, sigversion);
+    }
+
+    bool CheckSchnorrSignature(Span<const unsigned char> sig, Span<const unsigned char> pubkey, SigVersion sigversion, const ScriptExecutionData& execdata, ScriptError* serror = nullptr) const override
+    {
+        return m_checker.CheckSchnorrSignature(sig, pubkey, sigversion, execdata, serror);
+    }
+
+    bool CheckLockTime(const CScriptNum& nLockTime) const override
+    {
+        return m_checker.CheckLockTime(nLockTime);
+    }
+    bool CheckSequence(const CScriptNum& nSequence) const override
+    {
+        return m_checker.CheckSequence(nSequence);
+    }
+};
+
 bool EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript& script, unsigned int flags, const BaseSignatureChecker& checker, SigVersion sigversion, ScriptExecutionData& execdata, ScriptError* error = nullptr);
 bool EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript& script, unsigned int flags, const BaseSignatureChecker& checker, SigVersion sigversion, ScriptError* error = nullptr);
 bool VerifyScript(const CScript& scriptSig, const CScript& scriptPubKey, const CScriptWitness* witness, unsigned int flags, const BaseSignatureChecker& checker, ScriptError* serror = nullptr);
diff --git a/src/script/sign.cpp b/src/script/sign.cpp
index dba5ce621a..3c8f6d22ea 100644
--- a/src/script/sign.cpp
+++ b/src/script/sign.cpp
@@ -250,17 +250,17 @@ bool ProduceSignature(const SigningProvider& provider, const BaseSignatureCreato
 }
 
 namespace {
-class SignatureExtractorChecker final : public BaseSignatureChecker
+class SignatureExtractorChecker final : public DeferringSignatureChecker
 {
 private:
     SignatureData& sigdata;
-    BaseSignatureChecker& checker;
 
 public:
-    SignatureExtractorChecker(SignatureData& sigdata, BaseSignatureChecker& checker) : sigdata(sigdata), checker(checker) {}
+    SignatureExtractorChecker(SignatureData& sigdata, BaseSignatureChecker& checker) : DeferringSignatureChecker(checker), sigdata(sigdata) {}
+
     bool CheckECDSASignature(const std::vector<unsigned char>& scriptSig, const std::vector<unsigned char>& vchPubKey, const CScript& scriptCode, SigVersion sigversion) const override
     {
-        if (checker.CheckECDSASignature(scriptSig, vchPubKey, scriptCode, sigversion)) {
+        if (m_checker.CheckECDSASignature(scriptSig, vchPubKey, scriptCode, sigversion)) {
             CPubKey pubkey(vchPubKey);
             sigdata.signatures.emplace(pubkey.GetID(), SigPair(pubkey, scriptSig));
             return true;