BIP141: Other consensus critical limits, and BIP145

Includes changes by Suhas Daftuar, Luke-jr, and mruddy.

1 files changed, 51 insertions, 27 deletions

diff --git a/src/main.cpp b/src/main.cpp
index c22faf6db6..df758bc41f 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -684,8 +684,8 @@ bool AddOrphanTx(const CTransaction& tx, NodeId peer) EXCLUSIVE_LOCKS_REQUIRED(c
     // have been mined or received.
     // 100 orphans, each of which is at most 99,999 bytes big is
     // at most 10 megabytes of orphans and somewhat more byprev index (in the worst case):
-    unsigned int sz = tx.GetSerializeSize(SER_NETWORK, CTransaction::CURRENT_VERSION);
-    if (sz >= MAX_STANDARD_TX_SIZE)
+    unsigned int sz = GetTransactionCost(tx);
+    if (sz >= MAX_STANDARD_TX_COST)
     {
         LogPrint("mempool", "ignoring large orphan tx (size: %u, hash: %s)\n", sz, hash.ToString());
         return false;
@@ -1018,8 +1018,24 @@ unsigned int GetP2SHSigOpCount(const CTransaction& tx, const CCoinsViewCache& in
     return nSigOps;
 }
 
+int64_t GetTransactionSigOpCost(const CTransaction& tx, const CCoinsViewCache& inputs, int flags)
+{
+    int64_t nSigOps = GetLegacySigOpCount(tx) * WITNESS_SCALE_FACTOR;
+
+    if (tx.IsCoinBase())
+        return nSigOps;
 
+    if (flags & SCRIPT_VERIFY_P2SH) {
+        nSigOps += GetP2SHSigOpCount(tx, inputs) * WITNESS_SCALE_FACTOR;
+    }
 
+    for (unsigned int i = 0; i < tx.vin.size(); i++)
+    {
+        const CTxOut &prevout = inputs.GetOutputFor(tx.vin[i]);
+        nSigOps += CountWitnessSigOps(tx.vin[i].scriptSig, prevout.scriptPubKey, i < tx.wit.vtxinwit.size() ? &tx.wit.vtxinwit[i].scriptWitness : NULL, flags);
+    }
+    return nSigOps;
+}
 
 
 
@@ -1033,7 +1049,7 @@ bool CheckTransaction(const CTransaction& tx, CValidationState &state)
     if (tx.vout.empty())
         return state.DoS(10, false, REJECT_INVALID, "bad-txns-vout-empty");
     // Size limits (this doesn't take the witness into account, as that hasn't been checked for malleability)
-    if (::GetSerializeSize(tx, SER_NETWORK, PROTOCOL_VERSION | SERIALIZE_TRANSACTION_NO_WITNESS) > MAX_BLOCK_SIZE)
+    if (::GetSerializeSize(tx, SER_NETWORK, PROTOCOL_VERSION | SERIALIZE_TRANSACTION_NO_WITNESS) > MAX_BLOCK_BASE_SIZE)
         return state.DoS(100, false, REJECT_INVALID, "bad-txns-oversize");
 
     // Check for negative or overflow output values
@@ -1239,8 +1255,7 @@ bool AcceptToMemoryPoolWorker(CTxMemPool& pool, CValidationState& state, const C
         if (fRequireStandard && !AreInputsStandard(tx, view))
             return state.Invalid(false, REJECT_NONSTANDARD, "bad-txns-nonstandard-inputs");
 
-        unsigned int nSigOps = GetLegacySigOpCount(tx);
-        nSigOps += GetP2SHSigOpCount(tx, view);
+        int64_t nSigOpsCost = GetTransactionSigOpCost(tx, view, STANDARD_SCRIPT_VERIFY_FLAGS);
 
         CAmount nValueOut = tx.GetValueOut();
         CAmount nFees = nValueIn-nValueOut;
@@ -1263,7 +1278,7 @@ bool AcceptToMemoryPoolWorker(CTxMemPool& pool, CValidationState& state, const C
             }
         }
 
-        CTxMemPoolEntry entry(tx, nFees, GetTime(), dPriority, chainActive.Height(), pool.HasNoInputsOf(tx), inChainInputValue, fSpendsCoinbase, nSigOps, lp);
+        CTxMemPoolEntry entry(tx, nFees, GetTime(), dPriority, chainActive.Height(), pool.HasNoInputsOf(tx), inChainInputValue, fSpendsCoinbase, nSigOpsCost, lp);
         unsigned int nSize = entry.GetTxSize();
 
         // Check that the transaction doesn't have an excessive number of
@@ -1271,9 +1286,9 @@ bool AcceptToMemoryPoolWorker(CTxMemPool& pool, CValidationState& state, const C
         // itself can contain sigops MAX_STANDARD_TX_SIGOPS is less than
         // MAX_BLOCK_SIGOPS; we still consider this an invalid rather than
         // merely non-standard transaction.
-        if ((nSigOps > MAX_STANDARD_TX_SIGOPS) || (nBytesPerSigOp && nSigOps > nSize / nBytesPerSigOp))
+        if ((nSigOpsCost > MAX_STANDARD_TX_SIGOPS_COST) || (nBytesPerSigOp && nSigOpsCost > nSize * WITNESS_SCALE_FACTOR / nBytesPerSigOp))
             return state.DoS(0, false, REJECT_NONSTANDARD, "bad-txns-too-many-sigops", false,
-                strprintf("%d", nSigOps));
+                strprintf("%d", nSigOpsCost));
 
         CAmount mempoolRejectFee = pool.GetMinFee(GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000).GetFee(nSize);
         if (mempoolRejectFee > 0 && nModifiedFees < mempoolRejectFee) {
@@ -2439,7 +2454,7 @@ bool ConnectBlock(const CBlock& block, CValidationState& state, CBlockIndex* pin
     std::vector<int> prevheights;
     CAmount nFees = 0;
     int nInputs = 0;
-    unsigned int nSigOps = 0;
+    int64_t nSigOpsCost = 0;
     CDiskTxPos pos(pindex->GetBlockPos(), GetSizeOfCompactSize(block.vtx.size()));
     std::vector<std::pair<uint256, CDiskTxPos> > vPos;
     vPos.reserve(block.vtx.size());
@@ -2449,10 +2464,6 @@ bool ConnectBlock(const CBlock& block, CValidationState& state, CBlockIndex* pin
         const CTransaction &tx = block.vtx[i];
 
         nInputs += tx.vin.size();
-        nSigOps += GetLegacySigOpCount(tx);
-        if (nSigOps > MAX_BLOCK_SIGOPS)
-            return state.DoS(100, error("ConnectBlock(): too many sigops"),
-                             REJECT_INVALID, "bad-blk-sigops");
 
         if (!tx.IsCoinBase())
         {
@@ -2483,18 +2494,19 @@ bool ConnectBlock(const CBlock& block, CValidationState& state, CBlockIndex* pin
                 return state.DoS(100, error("%s: contains a non-BIP68-final transaction", __func__),
                                  REJECT_INVALID, "bad-txns-nonfinal");
             }
+        }
 
-            if (fStrictPayToScriptHash)
-            {
-                // Add in sigops done by pay-to-script-hash inputs;
-                // this is to prevent a "rogue miner" from creating
-                // an incredibly-expensive-to-validate block.
-                nSigOps += GetP2SHSigOpCount(tx, view);
-                if (nSigOps > MAX_BLOCK_SIGOPS)
-                    return state.DoS(100, error("ConnectBlock(): too many sigops"),
-                                     REJECT_INVALID, "bad-blk-sigops");
-            }
+        // GetTransactionSigOpCost counts 3 types of sigops:
+        // * legacy (always)
+        // * p2sh (when P2SH enabled in flags and excludes coinbase)
+        // * witness (when witness enabled in flags and excludes coinbase)
+        nSigOpsCost += GetTransactionSigOpCost(tx, view, flags);
+        if (nSigOpsCost > MAX_BLOCK_SIGOPS_COST)
+            return state.DoS(100, error("ConnectBlock(): too many sigops"),
+                             REJECT_INVALID, "bad-blk-sigops");
 
+        if (!tx.IsCoinBase())
+        {
             nFees += view.GetValueIn(tx)-tx.GetValueOut();
 
             std::vector<CScriptCheck> vChecks;
@@ -3417,9 +3429,11 @@ bool CheckBlock(const CBlock& block, CValidationState& state, const Consensus::P
     // All potential-corruption validation must be done before we do any
     // transaction validation, as otherwise we may mark the header as invalid
     // because we receive the wrong transactions for it.
+    // Note that witness malleability is checked in ContextualCheckBlock, so no
+    // checks that use witness data may be performed here.
 
     // Size limits
-    if (block.vtx.empty() || block.vtx.size() > MAX_BLOCK_SIZE || ::GetSerializeSize(block, SER_NETWORK, PROTOCOL_VERSION | SERIALIZE_TRANSACTION_NO_WITNESS) > MAX_BLOCK_SIZE)
+    if (block.vtx.empty() || block.vtx.size() > MAX_BLOCK_BASE_SIZE || ::GetSerializeSize(block, SER_NETWORK, PROTOCOL_VERSION | SERIALIZE_TRANSACTION_NO_WITNESS) > MAX_BLOCK_BASE_SIZE)
         return state.DoS(100, false, REJECT_INVALID, "bad-blk-length", false, "size limits failed");
 
     // First transaction must be coinbase, the rest must not be
@@ -3440,7 +3454,7 @@ bool CheckBlock(const CBlock& block, CValidationState& state, const Consensus::P
     {
         nSigOps += GetLegacySigOpCount(tx);
     }
-    if (nSigOps > MAX_BLOCK_SIGOPS)
+    if (nSigOps * WITNESS_SCALE_FACTOR > MAX_BLOCK_SIGOPS_COST)
         return state.DoS(100, false, REJECT_INVALID, "bad-blk-sigops", false, "out-of-bounds SigOpCount");
 
     if (fCheckPOW && fCheckMerkleRoot)
@@ -3621,6 +3635,16 @@ bool ContextualCheckBlock(const CBlock& block, CValidationState& state, CBlockIn
         }
     }
 
+    // After the coinbase witness nonce and commitment are verified,
+    // we can check if the block cost passes (before we've checked the
+    // coinbase witness, it would be possible for the cost to be too
+    // large by filling up the coinbase witness, which doesn't change
+    // the block hash, so we couldn't mark the block as permanently
+    // failed).
+    if (GetBlockCost(block) > MAX_BLOCK_COST) {
+        return state.DoS(100, error("ContextualCheckBlock(): cost limit failed"), REJECT_INVALID, "bad-blk-cost");
+    }
+
     return true;
 }
 
@@ -4284,7 +4308,7 @@ bool LoadExternalBlockFile(const CChainParams& chainparams, FILE* fileIn, CDiskB
     int nLoaded = 0;
     try {
         // This takes over fileIn and calls fclose() on it in the CBufferedFile destructor
-        CBufferedFile blkdat(fileIn, 2*MAX_BLOCK_SIZE, MAX_BLOCK_SIZE+8, SER_DISK, CLIENT_VERSION);
+        CBufferedFile blkdat(fileIn, 2*MAX_BLOCK_SERIALIZED_SIZE, MAX_BLOCK_SERIALIZED_SIZE+8, SER_DISK, CLIENT_VERSION);
         uint64_t nRewind = blkdat.GetPos();
         while (!blkdat.eof()) {
             boost::this_thread::interruption_point();
@@ -4303,7 +4327,7 @@ bool LoadExternalBlockFile(const CChainParams& chainparams, FILE* fileIn, CDiskB
                     continue;
                 // read size
                 blkdat >> nSize;
-                if (nSize < 80 || nSize > MAX_BLOCK_SIZE)
+                if (nSize < 80 || nSize > MAX_BLOCK_SERIALIZED_SIZE)
                     continue;
             } catch (const std::exception&) {
                 // no valid block header found; don't complain