From 99d0d0f356c3237ad1ef416f179c45797cecb89b Mon Sep 17 00:00:00 2001
From: Pieter Wuille <pieter.wuille@gmail.com>
Date: Tue, 13 Nov 2012 23:03:25 +0100
Subject: Introduce script verification flags

These flags select features to be enabled/disabled during script
evaluation/checking, instead of several booleans passed along.
Currently these flags are defined:
* SCRIPT_VERIFY_P2SH: enable BIP16-style subscript evaluation
* SCRIPT_VERIFY_STRICTENC: enforce strict adherence to pubkey/sig encoding standards.
---
 src/script.cpp | 26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

(limited to 'src/script.cpp')

diff --git a/src/script.cpp b/src/script.cpp
index 36d208c247..a40ae5b1db 100644
--- a/src/script.cpp
+++ b/src/script.cpp
@@ -314,7 +314,7 @@ bool IsCanonicalSignature(const valtype &vchSig) {
     return true;
 }
 
-bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, const CTransaction& txTo, unsigned int nIn, bool fStrictEncodings, int nHashType)
+bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, const CTransaction& txTo, unsigned int nIn, unsigned int flags, int nHashType)
 {
     CAutoBN_CTX pctx;
     CScript::const_iterator pc = script.begin();
@@ -327,7 +327,7 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, co
     if (script.size() > 10000)
         return false;
     int nOpCount = 0;
-
+    bool fStrictEncodings = flags & SCRIPT_VERIFY_STRICTENC;
 
     try
     {
@@ -1637,14 +1637,14 @@ bool ExtractDestinations(const CScript& scriptPubKey, txnouttype& typeRet, vecto
 }
 
 bool VerifyScript(const CScript& scriptSig, const CScript& scriptPubKey, const CTransaction& txTo, unsigned int nIn,
-                  bool fValidatePayToScriptHash, bool fStrictEncodings, int nHashType)
+                  unsigned int flags, int nHashType)
 {
     vector<vector<unsigned char> > stack, stackCopy;
-    if (!EvalScript(stack, scriptSig, txTo, nIn, fStrictEncodings, nHashType))
+    if (!EvalScript(stack, scriptSig, txTo, nIn, flags, nHashType))
         return false;
-    if (fValidatePayToScriptHash)
+    if (flags & SCRIPT_VERIFY_P2SH)
         stackCopy = stack;
-    if (!EvalScript(stack, scriptPubKey, txTo, nIn, fStrictEncodings, nHashType))
+    if (!EvalScript(stack, scriptPubKey, txTo, nIn, flags, nHashType))
         return false;
     if (stack.empty())
         return false;
@@ -1653,7 +1653,7 @@ bool VerifyScript(const CScript& scriptSig, const CScript& scriptPubKey, const C
         return false;
 
     // Additional validation for spend-to-script-hash transactions:
-    if (fValidatePayToScriptHash && scriptPubKey.IsPayToScriptHash())
+    if ((flags & SCRIPT_VERIFY_P2SH) && scriptPubKey.IsPayToScriptHash())
     {
         if (!scriptSig.IsPushOnly()) // scriptSig must be literals-only
             return false;            // or validation fails
@@ -1662,7 +1662,7 @@ bool VerifyScript(const CScript& scriptSig, const CScript& scriptPubKey, const C
         CScript pubKey2(pubKeySerialized.begin(), pubKeySerialized.end());
         popstack(stackCopy);
 
-        if (!EvalScript(stackCopy, pubKey2, txTo, nIn, fStrictEncodings, nHashType))
+        if (!EvalScript(stackCopy, pubKey2, txTo, nIn, flags, nHashType))
             return false;
         if (stackCopy.empty())
             return false;
@@ -1705,7 +1705,7 @@ bool SignSignature(const CKeyStore &keystore, const CScript& fromPubKey, CTransa
     }
 
     // Test solution
-    return VerifyScript(txin.scriptSig, fromPubKey, txTo, nIn, true, true, 0);
+    return VerifyScript(txin.scriptSig, fromPubKey, txTo, nIn, SCRIPT_VERIFY_P2SH | SCRIPT_VERIFY_STRICTENC, 0);
 }
 
 bool SignSignature(const CKeyStore &keystore, const CTransaction& txFrom, CTransaction& txTo, unsigned int nIn, int nHashType)
@@ -1718,7 +1718,7 @@ bool SignSignature(const CKeyStore &keystore, const CTransaction& txFrom, CTrans
     return SignSignature(keystore, txout.scriptPubKey, txTo, nIn, nHashType);
 }
 
-bool VerifySignature(const CCoins& txFrom, const CTransaction& txTo, unsigned int nIn, bool fValidatePayToScriptHash, bool fStrictEncodings, int nHashType)
+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];
@@ -1726,7 +1726,7 @@ bool VerifySignature(const CCoins& txFrom, const CTransaction& txTo, unsigned in
         return false;
     const CTxOut& txout = txFrom.vout[txin.prevout.n];
 
-    return VerifyScript(txin.scriptSig, txout.scriptPubKey, txTo, nIn, fValidatePayToScriptHash, fStrictEncodings, nHashType);
+    return VerifyScript(txin.scriptSig, txout.scriptPubKey, txTo, nIn, flags, nHashType);
 }
 
 static CScript PushAll(const vector<valtype>& values)
@@ -1844,9 +1844,9 @@ CScript CombineSignatures(CScript scriptPubKey, const CTransaction& txTo, unsign
     Solver(scriptPubKey, txType, vSolutions);
 
     vector<valtype> stack1;
-    EvalScript(stack1, scriptSig1, CTransaction(), 0, true, 0);
+    EvalScript(stack1, scriptSig1, CTransaction(), 0, SCRIPT_VERIFY_STRICTENC, 0);
     vector<valtype> stack2;
-    EvalScript(stack2, scriptSig2, CTransaction(), 0, true, 0);
+    EvalScript(stack2, scriptSig2, CTransaction(), 0, SCRIPT_VERIFY_STRICTENC, 0);
 
     return CombineSignatures(scriptPubKey, txTo, nIn, txType, vSolutions, stack1, stack2);
 }
-- 
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