From 68f7d1d7af39a8ea6510f888e8e058e8e8faa007 Mon Sep 17 00:00:00 2001
From: Peter Todd <pete@petertodd.org>
Date: Mon, 10 Mar 2014 17:31:46 -0400
Subject: [PATCH] Create (MANDATORY|STANDARD)_SCRIPT_VERIFY_FLAGS constants

---
 src/main.cpp              |  2 +-
 src/main.h                |  2 +-
 src/miner.cpp             |  5 ++++-
 src/rpcrawtransaction.cpp |  2 +-
 src/script.cpp            |  2 +-
 src/script.h              | 12 ++++++++++++
 6 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/src/main.cpp b/src/main.cpp
index 40c713ce9..cee9d027f 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -945,7 +945,7 @@ bool AcceptToMemoryPool(CTxMemPool& pool, CValidationState &state, const CTransa
 
         // Check against previous transactions
         // This is done last to help prevent CPU exhaustion denial-of-service attacks.
-        if (!CheckInputs(tx, state, view, true, SCRIPT_VERIFY_P2SH | SCRIPT_VERIFY_STRICTENC))
+        if (!CheckInputs(tx, state, view, true, STANDARD_SCRIPT_VERIFY_FLAGS))
         {
             return error("AcceptToMemoryPool: : ConnectInputs failed %s", hash.ToString());
         }
diff --git a/src/main.h b/src/main.h
index 825e577d1..470f15828 100644
--- a/src/main.h
+++ b/src/main.h
@@ -309,7 +309,7 @@ inline bool AllowFree(double dPriority)
 // This does not modify the UTXO set. If pvChecks is not NULL, script checks are pushed onto it
 // instead of being performed inline.
 bool CheckInputs(const CTransaction& tx, CValidationState &state, CCoinsViewCache &view, bool fScriptChecks = true,
-                 unsigned int flags = SCRIPT_VERIFY_P2SH | SCRIPT_VERIFY_STRICTENC,
+                 unsigned int flags = STANDARD_SCRIPT_VERIFY_FLAGS,
                  std::vector<CScriptCheck> *pvChecks = NULL);
 
 // Apply the effects of this transaction on the UTXO set represented by view
diff --git a/src/miner.cpp b/src/miner.cpp
index 3351908e6..12a5e7f84 100644
--- a/src/miner.cpp
+++ b/src/miner.cpp
@@ -276,8 +276,11 @@ CBlockTemplate* CreateNewBlock(const CScript& scriptPubKeyIn)
             if (nBlockSigOps + nTxSigOps >= MAX_BLOCK_SIGOPS)
                 continue;
 
+            // Note that flags: we don't want to set mempool/IsStandard()
+            // policy here, but we still have to ensure that the block we
+            // create only contains transactions that are valid in new blocks.
             CValidationState state;
-            if (!CheckInputs(tx, state, view, true, SCRIPT_VERIFY_P2SH))
+            if (!CheckInputs(tx, state, view, true, MANDATORY_SCRIPT_VERIFY_FLAGS))
                 continue;
 
             CTxUndo txundo;
diff --git a/src/rpcrawtransaction.cpp b/src/rpcrawtransaction.cpp
index 4b7dd617e..70a5bdf29 100644
--- a/src/rpcrawtransaction.cpp
+++ b/src/rpcrawtransaction.cpp
@@ -722,7 +722,7 @@ Value signrawtransaction(const Array& params, bool fHelp)
         {
             txin.scriptSig = CombineSignatures(prevPubKey, mergedTx, i, txin.scriptSig, txv.vin[i].scriptSig);
         }
-        if (!VerifyScript(txin.scriptSig, prevPubKey, mergedTx, i, SCRIPT_VERIFY_P2SH | SCRIPT_VERIFY_STRICTENC, 0))
+        if (!VerifyScript(txin.scriptSig, prevPubKey, mergedTx, i, STANDARD_SCRIPT_VERIFY_FLAGS, 0))
             fComplete = false;
     }
 
diff --git a/src/script.cpp b/src/script.cpp
index 810ba16d2..dc0cd28bf 100644
--- a/src/script.cpp
+++ b/src/script.cpp
@@ -1670,7 +1670,7 @@ bool SignSignature(const CKeyStore &keystore, const CScript& fromPubKey, CTransa
     }
 
     // Test solution
-    return VerifyScript(txin.scriptSig, fromPubKey, txTo, nIn, SCRIPT_VERIFY_P2SH | SCRIPT_VERIFY_STRICTENC, 0);
+    return VerifyScript(txin.scriptSig, fromPubKey, txTo, nIn, STANDARD_SCRIPT_VERIFY_FLAGS, 0);
 }
 
 bool SignSignature(const CKeyStore &keystore, const CTransaction& txFrom, CTransaction& txTo, unsigned int nIn, int nHashType)
diff --git a/src/script.h b/src/script.h
index 657ac0b38..0f26fb556 100644
--- a/src/script.h
+++ b/src/script.h
@@ -44,6 +44,18 @@ enum
     SCRIPT_VERIFY_NOCACHE   = (1U << 3), // do not store results in signature cache (but do query it)
 };
 
+// Mandatory script verification flags that all new blocks must comply with for
+// them to be valid. (but old blocks may not comply with) Currently just P2SH,
+// but in the future other flags may be added, such as a soft-fork to enforce
+// strict DER encoding.
+static const unsigned int MANDATORY_SCRIPT_VERIFY_FLAGS = SCRIPT_VERIFY_P2SH;
+
+// Standard script verification flags that standard transactions will comply
+// with. However scripts violating these flags may still be present in valid
+// blocks and we must accept those blocks.
+static const unsigned int STANDARD_SCRIPT_VERIFY_FLAGS = MANDATORY_SCRIPT_VERIFY_FLAGS |
+                                                         SCRIPT_VERIFY_STRICTENC;
+
 enum txnouttype
 {
     TX_NONSTANDARD,