Consensus: Refactor: Separate Consensus::CheckTxInputs and GetSpendHeight in CheckInputs

Zcash:
- Replaces some of the refactoring performed in #1017
- Exposed Consensus::CheckTxInputs for testing

src/main.cpp

@@ -1607,13 +1607,16 @@ bool CScriptCheck::operator()() {
     return true;
 }
 
-bool NonContextualCheckInputs(const CTransaction& tx, CValidationState &state, const CCoinsViewCache &inputs, bool fScriptChecks, unsigned int flags, bool cacheStore, const Consensus::Params& consensusParams, std::vector<CScriptCheck> *pvChecks)
+int GetSpendHeight(const CCoinsViewCache& inputs)
 {
-    if (!tx.IsCoinBase())
-    {
-        if (pvChecks)
-            pvChecks->reserve(tx.vin.size());
+    LOCK(cs_main);
+    CBlockIndex* pindexPrev = mapBlockIndex.find(inputs.GetBestBlock())->second;
+    return pindexPrev->nHeight + 1;
+}
 
+namespace Consensus {
+bool CheckTxInputs(const CTransaction& tx, CValidationState& state, const CCoinsViewCache& inputs, int nSpendHeight, const Consensus::Params& consensusParams)
+{
         // This doesn't trigger the DoS code on purpose; if it did, it would make it easier
         // for an attacker to attempt to split the network.
         if (!inputs.HaveInputs(tx))
@@ -1632,6 +1635,13 @@ bool NonContextualCheckInputs(const CTransaction& tx, CValidationState &state, c
             assert(coins);
 
             if (coins->IsCoinBase()) {
+                // Ensure that coinbases are matured
+                if (nSpendHeight - coins->nHeight < COINBASE_MATURITY) {
+                    return state.Invalid(
+                        error("CheckInputs(): tried to spend coinbase at depth %d", nSpendHeight - coins->nHeight),
+                        REJECT_INVALID, "bad-txns-premature-spend-of-coinbase");
+                }
+
                 // Ensure that coinbases cannot be spent to transparent outputs
                 // Disabled on regtest
                 if (fCoinbaseEnforcedProtectionEnabled &&
@@ -1670,6 +1680,19 @@ bool NonContextualCheckInputs(const CTransaction& tx, CValidationState &state, c
         if (!MoneyRange(nFees))
             return state.DoS(100, error("CheckInputs(): nFees out of range"),
                              REJECT_INVALID, "bad-txns-fee-outofrange");
+    return true;
+}
+}// namespace Consensus
+
+bool ContextualCheckInputs(const CTransaction& tx, CValidationState &state, const CCoinsViewCache &inputs, bool fScriptChecks, unsigned int flags, bool cacheStore, const Consensus::Params& consensusParams, std::vector<CScriptCheck> *pvChecks)
+{
+    if (!Consensus::CheckTxInputs(tx, state, inputs, GetSpendHeight(inputs), consensusParams))
+        return false;
+
+    if (!tx.IsCoinBase())
+    {
+        if (pvChecks)
+            pvChecks->reserve(tx.vin.size());
 
         // The first loop above does all the inexpensive checks.
         // Only if ALL inputs pass do we perform expensive ECDSA signature checks.
@@ -1718,40 +1741,6 @@ bool NonContextualCheckInputs(const CTransaction& tx, CValidationState &state, c
     return true;
 }
 
-bool ContextualCheckInputs(const CTransaction& tx, CValidationState &state, const CCoinsViewCache &inputs, bool fScriptChecks, unsigned int flags, bool cacheStore, const Consensus::Params& consensusParams, std::vector<CScriptCheck> *pvChecks)
-{
-    if (!NonContextualCheckInputs(tx, state, inputs, fScriptChecks, flags, cacheStore, consensusParams, pvChecks)) {
-        return false;
-    }
-
-    if (!tx.IsCoinBase())
-    {
-        // While checking, GetBestBlock() refers to the parent block.
-        // This is also true for mempool checks.
-        CBlockIndex *pindexPrev = mapBlockIndex.find(inputs.GetBestBlock())->second;
-        int nSpendHeight = pindexPrev->nHeight + 1;
-        for (unsigned int i = 0; i < tx.vin.size(); i++)
-        {
-            const COutPoint &prevout = tx.vin[i].prevout;
-            const CCoins *coins = inputs.AccessCoins(prevout.hash);
-            // Assertion is okay because NonContextualCheckInputs ensures the inputs
-            // are available.
-            assert(coins);
-
-            // If prev is coinbase, check that it's matured
-            if (coins->IsCoinBase()) {
-                if (nSpendHeight - coins->nHeight < COINBASE_MATURITY) {
-                    return state.Invalid(
-                        error("CheckInputs(): tried to spend coinbase at depth %d", nSpendHeight - coins->nHeight),
-                        REJECT_INVALID, "bad-txns-premature-spend-of-coinbase");
-                }
-            }
-        }
-    }
-
-    return true;
-}
-
 namespace {
 
 bool UndoWriteToDisk(const CBlockUndo& blockundo, CDiskBlockPos& pos, const uint256& hashBlock, const CMessageHeader::MessageStartChars& messageStart)

src/main.h

@@ -332,10 +332,6 @@ bool ContextualCheckInputs(const CTransaction& tx, CValidationState &state, cons
                            unsigned int flags, bool cacheStore, const Consensus::Params& consensusParams,
                            std::vector<CScriptCheck> *pvChecks = NULL);
 
-bool NonContextualCheckInputs(const CTransaction& tx, CValidationState &state, const CCoinsViewCache &view, bool fScriptChecks,
-                              unsigned int flags, bool cacheStore, const Consensus::Params& consensusParams,
-                              std::vector<CScriptCheck> *pvChecks = NULL);
-
 /** Apply the effects of this transaction on the UTXO set represented by view */
 void UpdateCoins(const CTransaction& tx, CValidationState &state, CCoinsViewCache &inputs, int nHeight);
 
@@ -520,4 +516,15 @@ extern CCoinsViewCache *pcoinsTip;
 /** Global variable that points to the active block tree (protected by cs_main) */
 extern CBlockTreeDB *pblocktree;
 
+/**
+ * Return the spend height, which is one more than the inputs.GetBestBlock().
+ * While checking, GetBestBlock() refers to the parent block. (protected by cs_main)
+ * This is also true for mempool checks.
+ */
+int GetSpendHeight(const CCoinsViewCache& inputs);
+
+namespace Consensus {
+bool CheckTxInputs(const CTransaction& tx, CValidationState& state, const CCoinsViewCache& inputs, int nSpendHeight, const Consensus::Params& consensusParams);
+}
+
 #endif // BITCOIN_MAIN_H

src/test/coins_tests.cpp

@@ -756,7 +756,7 @@ BOOST_AUTO_TEST_CASE(coins_coinbase_spends)
 
     {
         CTransaction tx2(mtx2);
-        BOOST_CHECK(NonContextualCheckInputs(tx2, state, cache, false, SCRIPT_VERIFY_NONE, false, Params().GetConsensus()));
+        BOOST_CHECK(Consensus::CheckTxInputs(tx2, state, cache, 100+COINBASE_MATURITY, Params().GetConsensus()));
     }
 
     mtx2.vout.resize(1);
@@ -765,7 +765,7 @@ BOOST_AUTO_TEST_CASE(coins_coinbase_spends)
 
     {
         CTransaction tx2(mtx2);
-        BOOST_CHECK(!NonContextualCheckInputs(tx2, state, cache, false, SCRIPT_VERIFY_NONE, false, Params().GetConsensus()));
+        BOOST_CHECK(!Consensus::CheckTxInputs(tx2, state, cache, 100+COINBASE_MATURITY, Params().GetConsensus()));
         BOOST_CHECK(state.GetRejectReason() == "bad-txns-coinbase-spend-has-transparent-outputs");
     }
 }