From 2800ce7367760a9bb8fd5209feddf71e574a592d Mon Sep 17 00:00:00 2001
From: Pieter Wuille <pieter.wuille@gmail.com>
Date: Sat, 1 Dec 2012 22:30:06 +0100
Subject: [PATCH] Add CScriptCheck: a closure representing a script check

---
 src/main.cpp | 15 ++++++++-------
 src/main.h   | 27 ++++++++++++++++++++++++++-
 2 files changed, 34 insertions(+), 8 deletions(-)

diff --git a/src/main.cpp b/src/main.cpp
index c0446370a..4441c65fd 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1348,15 +1348,16 @@ bool CTransaction::HaveInputs(CCoinsViewCache &inputs) const
     return true;
 }
 
+bool CScriptCheck::operator()() const {
+    const CScript &scriptSig = ptxTo->vin[nIn].scriptSig;
+    if (!VerifyScript(scriptSig, scriptPubKey, *ptxTo, nIn, nFlags, nHashType))
+        return error("CScriptCheck() : %s VerifySignature failed", ptxTo->GetHash().ToString().substr(0,10).c_str());
+    return true;
+}
+
 bool VerifySignature(const CCoins& txFrom, const CTransaction& txTo, unsigned int nIn, unsigned int flags, int nHashType)
 {
-    assert(nIn < txTo.vin.size());
-    const CTxIn& txin = txTo.vin[nIn];
-    if (txin.prevout.n >= txFrom.vout.size())
-        return false;
-    const CTxOut& txout = txFrom.vout[txin.prevout.n];
-
-    return VerifyScript(txin.scriptSig, txout.scriptPubKey, txTo, nIn, flags, nHashType);
+    return CScriptCheck(txFrom, txTo, nIn, flags, nHashType)();
 }
 
 bool CTransaction::CheckInputs(CCoinsViewCache &inputs, enum CheckSig_mode csmode, unsigned int flags) const
diff --git a/src/main.h b/src/main.h
index a098cc775..83454e331 100644
--- a/src/main.h
+++ b/src/main.h
@@ -430,7 +430,6 @@ enum GetMinFee_mode
     GMF_SEND,
 };
 
-// Modes for script/signature checking
 enum CheckSig_mode
 {
     CS_NEVER,             // never validate scripts
@@ -1015,7 +1014,33 @@ public:
     }
 };
 
+/** Closure representing one script verification
+ *  Note that this stores references to the spending transaction */
+class CScriptCheck
+{
+private:
+    CScript scriptPubKey;
+    const CTransaction *ptxTo;
+    unsigned int nIn;
+    unsigned int nFlags;
+    int nHashType;
 
+public:
+    CScriptCheck() {}
+    CScriptCheck(const CCoins& txFromIn, const CTransaction& txToIn, unsigned int nInIn, unsigned int nFlagsIn, int nHashTypeIn) :
+        scriptPubKey(txFromIn.vout[txToIn.vin[nInIn].prevout.n].scriptPubKey),
+        ptxTo(&txToIn), nIn(nInIn), nFlags(nFlagsIn), nHashType(nHashTypeIn) { }
+
+    bool operator()() const;
+
+    void swap(CScriptCheck &check) {
+        scriptPubKey.swap(check.scriptPubKey);
+        std::swap(ptxTo, check.ptxTo);
+        std::swap(nIn, check.nIn);
+        std::swap(nFlags, check.nFlags);
+        std::swap(nHashType, check.nHashType);
+    }
+};
 
 /** A transaction with a merkle branch linking it to the block chain. */
 class CMerkleTx : public CTransaction