Merge #8524: Precompute sighashes

35fe039 Rename to PrecomputedTransactionData (Pieter Wuille)
ab48c5e Unit test for sighash caching (Nicolas DORIER)
d2c5d04 Precompute sighashes (Pieter Wuille)

add missing change from bitcoinconsensus.cpp

Signed-off-by: Pasta <Pasta@dash.org>

src/script/dashconsensus.cpp

@@ -94,7 +94,8 @@ int dashconsensus_verify_script(const unsigned char *scriptPubKey, unsigned int
         // Regardless of the verification result, the tx did not error.
         set_error(err, dashconsensus_ERR_OK);
 
-        return VerifyScript(tx.vin[nIn].scriptSig, CScript(scriptPubKey, scriptPubKey + scriptPubKeyLen), flags, TransactionSignatureChecker(&tx, nIn), NULL);
+        PrecomputedTransactionData txdata(tx);
+        return VerifyScript(tx.vin[nIn].scriptSig, CScript(scriptPubKey, scriptPubKey + scriptPubKeyLen), flags, TransactionSignatureChecker(&tx, nIn, txdata), NULL);
     } catch (const std::exception&) {
         return set_error(err, dashconsensus_ERR_TX_DESERIALIZE); // Error deserializing
     }

src/script/interpreter.cpp

@@ -1117,9 +1117,40 @@ public:
     }
 };
 
+uint256 GetPrevoutHash(const CTransaction& txTo) {
+    CHashWriter ss(SER_GETHASH, 0);
+    for (unsigned int n = 0; n < txTo.vin.size(); n++) {
+        ss << txTo.vin[n].prevout;
+    }
+    return ss.GetHash();
+}
+
+uint256 GetSequenceHash(const CTransaction& txTo) {
+    CHashWriter ss(SER_GETHASH, 0);
+    for (unsigned int n = 0; n < txTo.vin.size(); n++) {
+        ss << txTo.vin[n].nSequence;
+    }
+    return ss.GetHash();
+}
+
+uint256 GetOutputsHash(const CTransaction& txTo) {
+    CHashWriter ss(SER_GETHASH, 0);
+    for (unsigned int n = 0; n < txTo.vout.size(); n++) {
+        ss << txTo.vout[n];
+    }
+    return ss.GetHash();
+}
+
 } // anon namespace
 
-uint256 SignatureHash(const CScript& scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType)
+PrecomputedTransactionData::PrecomputedTransactionData(const CTransaction& txTo)
+{
+    hashPrevouts = GetPrevoutHash(txTo);
+    hashSequence = GetSequenceHash(txTo);
+    hashOutputs = GetOutputsHash(txTo);
+}
+
+uint256 SignatureHash(const CScript& scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType, const PrecomputedTransactionData* cache)
 {
     static const uint256 one(uint256S("0000000000000000000000000000000000000000000000000000000000000001"));
     if (nIn >= txTo.vin.size()) {
@@ -1162,7 +1193,7 @@ bool TransactionSignatureChecker::CheckSig(const std::vector<unsigned char>& vch
     int nHashType = vchSig.back();
     vchSig.pop_back();
 
-    uint256 sighash = SignatureHash(scriptCode, *txTo, nIn, nHashType);
+    uint256 sighash = SignatureHash(scriptCode, *txTo, nIn, nHashType, this->txdata);
 
     if (!VerifySignature(vchSig, pubkey, sighash))
         return false;

src/script/interpreter.h

@@ -94,7 +94,14 @@ enum
 
 bool CheckSignatureEncoding(const std::vector<unsigned char> &vchSig, unsigned int flags, ScriptError* serror);
 
-uint256 SignatureHash(const CScript &scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType);
+struct PrecomputedTransactionData
+{
+    uint256 hashPrevouts, hashSequence, hashOutputs;
+
+    PrecomputedTransactionData(const CTransaction& tx);
+};
+
+uint256 SignatureHash(const CScript &scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType, const PrecomputedTransactionData* cache = NULL);
 
 class BaseSignatureChecker
 {
@@ -122,12 +129,14 @@ class TransactionSignatureChecker : public BaseSignatureChecker
 private:
     const CTransaction* txTo;
     unsigned int nIn;
+    const PrecomputedTransactionData* txdata;
 
 protected:
     virtual bool VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& vchPubKey, const uint256& sighash) const;
 
 public:
-    TransactionSignatureChecker(const CTransaction* txToIn, unsigned int nInIn) : txTo(txToIn), nIn(nInIn) {}
+    TransactionSignatureChecker(const CTransaction* txToIn, unsigned int nInIn) : txTo(txToIn), nIn(nInIn), txdata(NULL) {}
+    TransactionSignatureChecker(const CTransaction* txToIn, unsigned int nInIn, const PrecomputedTransactionData& txdataIn) : txTo(txToIn), nIn(nInIn), txdata(&txdataIn) {}
     bool CheckSig(const std::vector<unsigned char>& scriptSig, const std::vector<unsigned char>& vchPubKey, const CScript& scriptCode) const override;
     bool CheckLockTime(const CScriptNum& nLockTime) const override;
     bool CheckSequence(const CScriptNum& nSequence) const override;

src/script/sigcache.h

@@ -46,7 +46,7 @@ private:
     bool store;
 
 public:
-    CachingTransactionSignatureChecker(const CTransaction* txToIn, unsigned int nInIn, bool storeIn=true) : TransactionSignatureChecker(txToIn, nInIn), store(storeIn) {}
+    CachingTransactionSignatureChecker(const CTransaction* txToIn, unsigned int nInIn, PrecomputedTransactionData& txdataIn, bool storeIn=true) : TransactionSignatureChecker(txToIn, nInIn, txdataIn), store(storeIn) {}
 
     bool VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& vchPubKey, const uint256& sighash) const override;
 };

src/test/script_P2SH_tests.cpp

@@ -104,13 +104,14 @@ BOOST_AUTO_TEST_CASE(sign)
     }
     // All of the above should be OK, and the txTos have valid signatures
     // Check to make sure signature verification fails if we use the wrong ScriptSig:
-    for (int i = 0; i < 8; i++)
+    for (int i = 0; i < 8; i++) {
+        PrecomputedTransactionData txdata(txTo[i]);
         for (int j = 0; j < 8; j++)
         {
             CScript sigSave = txTo[i].vin[0].scriptSig;
             txTo[i].vin[0].scriptSig = txTo[j].vin[0].scriptSig;
             const CTxOut& output = txFrom.vout[txTo[i].vin[0].prevout.n];
-            bool sigOK = CScriptCheck(output.scriptPubKey, output.nValue, txTo[i], 0, SCRIPT_VERIFY_P2SH | SCRIPT_VERIFY_STRICTENC, false)();
+            bool sigOK = CScriptCheck(output.scriptPubKey, output.nValue, txTo[i], 0, SCRIPT_VERIFY_P2SH | SCRIPT_VERIFY_STRICTENC, false, &txdata)();
             if (i == j)
                 BOOST_CHECK_MESSAGE(sigOK, strprintf("VerifySignature %d %d", i, j));
             else
@@ -118,6 +119,7 @@ BOOST_AUTO_TEST_CASE(sign)
             txTo[i].vin[0].scriptSig = sigSave;
         }
     }
+}
 
 BOOST_AUTO_TEST_CASE(norecurse)
 {

src/test/transaction_tests.cpp

@@ -7,6 +7,7 @@
 #include "test/test_dash.h"
 
 #include "clientversion.h"
+#include "checkqueue.h"
 #include "consensus/validation.h"
 #include "core_io.h"
 #include "key.h"
@@ -139,6 +140,7 @@ BOOST_AUTO_TEST_CASE(tx_valid)
             BOOST_CHECK_MESSAGE(CheckTransaction(tx, state), strTest);
             BOOST_CHECK(state.IsValid());
 
+            PrecomputedTransactionData txdata(tx);
             for (unsigned int i = 0; i < tx.vin.size(); i++)
             {
                 if (!mapprevOutScriptPubKeys.count(tx.vin[i].prevout))
@@ -149,7 +151,7 @@ BOOST_AUTO_TEST_CASE(tx_valid)
 
                 unsigned int verify_flags = ParseScriptFlags(test[2].get_str());
                 BOOST_CHECK_MESSAGE(VerifyScript(tx.vin[i].scriptSig, mapprevOutScriptPubKeys[tx.vin[i].prevout],
-                                                 verify_flags, TransactionSignatureChecker(&tx, i), &err),
+                                                 verify_flags, TransactionSignatureChecker(&tx, i, txdata), &err),
                                     strTest);
                 BOOST_CHECK_MESSAGE(err == SCRIPT_ERR_OK, ScriptErrorString(err));
             }
@@ -214,6 +216,7 @@ BOOST_AUTO_TEST_CASE(tx_invalid)
             CValidationState state;
             fValid = CheckTransaction(tx, state) && state.IsValid();
 
+            PrecomputedTransactionData txdata(tx);
             for (unsigned int i = 0; i < tx.vin.size() && fValid; i++)
             {
                 if (!mapprevOutScriptPubKeys.count(tx.vin[i].prevout))
@@ -224,7 +227,7 @@ BOOST_AUTO_TEST_CASE(tx_invalid)
 
                 unsigned int verify_flags = ParseScriptFlags(test[2].get_str());
                 fValid = VerifyScript(tx.vin[i].scriptSig, mapprevOutScriptPubKeys[tx.vin[i].prevout],
-                                      verify_flags, TransactionSignatureChecker(&tx, i), &err);
+                                      verify_flags, TransactionSignatureChecker(&tx, i, txdata), &err);
             }
             BOOST_CHECK_MESSAGE(!fValid, strTest);
             BOOST_CHECK_MESSAGE(err != SCRIPT_ERR_OK, ScriptErrorString(err));

src/validation.cpp

@@ -832,7 +832,8 @@ bool AcceptToMemoryPoolWorker(CTxMemPool& pool, CValidationState& state, const C
 
         // Check against previous transactions
         // This is done last to help prevent CPU exhaustion denial-of-service attacks.
-        if (!CheckInputs(tx, state, view, true, STANDARD_SCRIPT_VERIFY_FLAGS, true))
+        PrecomputedTransactionData txdata(tx);
+        if (!CheckInputs(tx, state, view, true, STANDARD_SCRIPT_VERIFY_FLAGS, true, txdata))
             return false; // state filled in by CheckInputs
 
         // Check again against just the consensus-critical mandatory script
@@ -844,7 +845,7 @@ bool AcceptToMemoryPoolWorker(CTxMemPool& pool, CValidationState& state, const C
         // There is a similar check in CreateNewBlock() to prevent creating
         // invalid blocks, however allowing such transactions into the mempool
         // can be exploited as a DoS attack.
-        if (!CheckInputs(tx, state, view, true, MANDATORY_SCRIPT_VERIFY_FLAGS, true))
+        if (!CheckInputs(tx, state, view, true, MANDATORY_SCRIPT_VERIFY_FLAGS, true, txdata))
         {
             return error("%s: BUG! PLEASE REPORT THIS! ConnectInputs failed against MANDATORY but not STANDARD flags %s, %s",
                 __func__, hash.ToString(), FormatStateMessage(state));
@@ -1331,7 +1332,8 @@ void UpdateCoins(const CTransaction& tx, CCoinsViewCache& inputs, int nHeight)
 
 bool CScriptCheck::operator()() {
     const CScript &scriptSig = ptxTo->vin[nIn].scriptSig;
-    if (!VerifyScript(scriptSig, scriptPubKey, nFlags, CachingTransactionSignatureChecker(ptxTo, nIn, cacheStore), &error)) {
+    PrecomputedTransactionData txdata(*ptxTo);
+    if (!VerifyScript(scriptSig, scriptPubKey, nFlags, CachingTransactionSignatureChecker(ptxTo, nIn, txdata, cacheStore), &error)) {
         return false;
     }
     return true;
@@ -1390,7 +1392,7 @@ bool CheckTxInputs(const CTransaction& tx, CValidationState& state, const CCoins
 }
 }// namespace Consensus
 
-bool CheckInputs(const CTransaction& tx, CValidationState &state, const CCoinsViewCache &inputs, bool fScriptChecks, unsigned int flags, bool cacheStore, std::vector<CScriptCheck> *pvChecks)
+bool CheckInputs(const CTransaction& tx, CValidationState &state, const CCoinsViewCache &inputs, bool fScriptChecks, unsigned int flags, bool cacheStore, PrecomputedTransactionData& txdata, std::vector<CScriptCheck> *pvChecks)
 {
     if (!tx.IsCoinBase())
     {
@@ -1424,7 +1426,7 @@ bool CheckInputs(const CTransaction& tx, CValidationState &state, const CCoinsVi
                 const CAmount amount = coin.out.nValue;
 
                 // Verify signature
-                CScriptCheck check(scriptPubKey, amount, tx, i, flags, cacheStore);
+                CScriptCheck check(scriptPubKey, amount, tx, i, flags, cacheStore, &txdata);
                 if (pvChecks) {
                     pvChecks->push_back(CScriptCheck());
                     check.swap(pvChecks->back());
@@ -1437,7 +1439,7 @@ bool CheckInputs(const CTransaction& tx, CValidationState &state, const CCoinsVi
                         // avoid splitting the network between upgraded and
                         // non-upgraded nodes.
                         CScriptCheck check2(scriptPubKey, amount, tx, i,
-                                flags & ~STANDARD_NOT_MANDATORY_VERIFY_FLAGS, cacheStore);
+                                flags & ~STANDARD_NOT_MANDATORY_VERIFY_FLAGS, cacheStore, &txdata);
                         if (check2())
                             return state.Invalid(false, REJECT_NONSTANDARD, strprintf("non-mandatory-script-verify-flag (%s)", ScriptErrorString(check.GetScriptError())));
                     }
@@ -2015,6 +2017,9 @@ static bool ConnectBlock(const CBlock& block, CValidationState& state, CBlockInd
     std::vector<std::pair<CAddressUnspentKey, CAddressUnspentValue> > addressUnspentIndex;
     std::vector<std::pair<CSpentIndexKey, CSpentIndexValue> > spentIndex;
 
+    std::vector<PrecomputedTransactionData> txdata;
+    txdata.reserve(block.vtx.size()); // Required so that pointers to individual PrecomputedTransactionData don't get invalidated
+
     bool fDIP0001Active_context = pindex->nHeight >= Params().GetConsensus().DIP0001Height;
 
     for (unsigned int i = 0; i < block.vtx.size(); i++)
@@ -2028,6 +2033,7 @@ static bool ConnectBlock(const CBlock& block, CValidationState& state, CBlockInd
             return state.DoS(100, error("ConnectBlock(): too many sigops"),
                              REJECT_INVALID, "bad-blk-sigops");
 
+        txdata.emplace_back(tx);
         if (!tx.IsCoinBase())
         {
             if (!view.HaveInputs(tx))
@@ -2102,7 +2108,7 @@ static bool ConnectBlock(const CBlock& block, CValidationState& state, CBlockInd
 
             std::vector<CScriptCheck> vChecks;
             bool fCacheResults = fJustCheck; /* Don't cache results if we're actually connecting blocks (still consult the cache, though) */
-            if (!CheckInputs(tx, state, view, fScriptChecks, flags, fCacheResults, nScriptCheckThreads ? &vChecks : NULL))
+            if (!CheckInputs(tx, state, view, fScriptChecks, flags, fCacheResults, txdata[i], nScriptCheckThreads ? &vChecks : NULL))
                 return error("ConnectBlock(): CheckInputs on %s failed with %s",
                     tx.GetHash().ToString(), FormatStateMessage(state));
             control.Add(vChecks);

src/validation.h

@@ -46,6 +46,7 @@ class CBlockPolicyEstimator;
 class CTxMemPool;
 class CValidationInterface;
 class CValidationState;
+class PrecomputedTransactionData;
 struct ChainTxData;
 
 struct LockPoints;
@@ -377,7 +378,7 @@ unsigned int GetP2SHSigOpCount(const CTransaction& tx, const CCoinsViewCache& ma
  * instead of being performed inline.
  */
 bool CheckInputs(const CTransaction& tx, CValidationState &state, const CCoinsViewCache &view, bool fScriptChecks,
-                 unsigned int flags, bool cacheStore, std::vector<CScriptCheck> *pvChecks = NULL);
+                 unsigned int flags, bool cacheStore, PrecomputedTransactionData& txdata, std::vector<CScriptCheck> *pvChecks = NULL);
 
 /** Apply the effects of this transaction on the UTXO set represented by view */
 void UpdateCoins(const CTransaction& tx, CCoinsViewCache& inputs, int nHeight);
@@ -450,12 +451,13 @@ private:
     unsigned int nFlags;
     bool cacheStore;
     ScriptError error;
+    PrecomputedTransactionData *txdata;
 
 public:
     CScriptCheck(): ptxTo(0), nIn(0), nFlags(0), cacheStore(false), error(SCRIPT_ERR_UNKNOWN_ERROR) {}
-    CScriptCheck(const CScript& scriptPubKeyIn, const CAmount amountIn, const CTransaction& txToIn, unsigned int nInIn, unsigned int nFlagsIn, bool cacheIn) :
+    CScriptCheck(const CScript& scriptPubKeyIn, const CAmount amountIn, const CTransaction& txToIn, unsigned int nInIn, unsigned int nFlagsIn, bool cacheIn, PrecomputedTransactionData* txdataIn) :
         scriptPubKey(scriptPubKeyIn),
-        ptxTo(&txToIn), nIn(nInIn), nFlags(nFlagsIn), cacheStore(cacheIn), error(SCRIPT_ERR_UNKNOWN_ERROR) { }
+        ptxTo(&txToIn), nIn(nInIn), nFlags(nFlagsIn), cacheStore(cacheIn), error(SCRIPT_ERR_UNKNOWN_ERROR), txdata(txdataIn) { }
 
     bool operator()();
 
@@ -466,6 +468,7 @@ public:
         std::swap(nFlags, check.nFlags);
         std::swap(cacheStore, check.cacheStore);
         std::swap(error, check.error);
+        std::swap(txdata, check.txdata);
     }
 
     ScriptError GetScriptError() const { return error; }