[refactor] Add versionbits deployments to deploymentstatus.h

Adds support for versionbits deployments to DeploymentEnabled,
DeploymentActiveAfter and DeploymentActiveAt. Also moves versionbitscache
from validation to deploymentstatus.

Author: ajtowns

src/Makefile.am

@@ -329,6 +329,7 @@ libbitcoin_server_a_SOURCES = \
   chain.cpp \
   consensus/tx_verify.cpp \
   dbwrapper.cpp \
+  deploymentstatus.cpp \
   flatfile.cpp \
   httprpc.cpp \
   httpserver.cpp \

src/consensus/params.h

@@ -22,13 +22,14 @@ enum BuriedDeployment : int16_t
 };
 constexpr bool ValidDeployment(BuriedDeployment dep) { return DEPLOYMENT_HEIGHTINCB <= dep && dep <= DEPLOYMENT_SEGWIT; }
 
-enum DeploymentPos
+enum DeploymentPos : uint16_t
 {
     DEPLOYMENT_TESTDUMMY,
     DEPLOYMENT_TAPROOT, // Deployment of Schnorr/Taproot (BIPs 340-342)
     // NOTE: Also add new deployments to VersionBitsDeploymentInfo in versionbits.cpp
     MAX_VERSION_BITS_DEPLOYMENTS
 };
+constexpr bool ValidDeployment(DeploymentPos dep) { return DEPLOYMENT_TESTDUMMY <= dep && dep <= DEPLOYMENT_TAPROOT; }
 
 /**
  * Struct for each individual consensus rule change using BIP9.

src/deploymentstatus.cpp

@@ -0,0 +1,17 @@
+// Copyright (c) 2020 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <deploymentstatus.h>
+
+#include <consensus/params.h>
+#include <versionbits.h>
+
+VersionBitsCache versionbitscache;
+
+/* Basic sanity checking for BuriedDeployment/DeploymentPos enums and
+ * ValidDeployment check */
+
+static_assert(ValidDeployment(Consensus::DEPLOYMENT_TESTDUMMY), "sanity check of DeploymentPos failed (TESTDUMMY not valid)");
+static_assert(!ValidDeployment(Consensus::MAX_VERSION_BITS_DEPLOYMENTS), "sanity check of DeploymentPos failed (MAX value considered valid)");
+static_assert(!ValidDeployment(static_cast<Consensus::BuriedDeployment>(Consensus::DEPLOYMENT_TESTDUMMY)), "sanity check of BuriedDeployment failed (overlaps with DeploymentPos)");

src/deploymentstatus.h

@@ -6,28 +6,50 @@
 #define BITCOIN_DEPLOYMENTSTATUS_H
 
 #include <chain.h>
+#include <versionbits.h>
 
 #include <limits>
 
+/** Global cache for versionbits deployment status */
+extern VersionBitsCache versionbitscache;
+
 /** Determine if a deployment is active for the next block */
 inline bool DeploymentActiveAfter(const CBlockIndex* pindexPrev, const Consensus::Params& params, Consensus::BuriedDeployment dep)
 {
     assert(Consensus::ValidDeployment(dep));
     return (pindexPrev == nullptr ? 0 : pindexPrev->nHeight + 1) >= params.DeploymentHeight(dep);
 }
 
+inline bool DeploymentActiveAfter(const CBlockIndex* pindexPrev, const Consensus::Params& params, Consensus::DeploymentPos dep)
+{
+    assert(Consensus::ValidDeployment(dep));
+    return ThresholdState::ACTIVE == VersionBitsState(pindexPrev, params, dep, versionbitscache);
+}
+
 /** Determine if a deployment is active for this block */
 inline bool DeploymentActiveAt(const CBlockIndex& index, const Consensus::Params& params, Consensus::BuriedDeployment dep)
 {
     assert(Consensus::ValidDeployment(dep));
     return index.nHeight >= params.DeploymentHeight(dep);
 }
 
+inline bool DeploymentActiveAt(const CBlockIndex& index, const Consensus::Params& params, Consensus::DeploymentPos dep)
+{
+    assert(Consensus::ValidDeployment(dep));
+    return DeploymentActiveAfter(index.pprev, params, dep);
+}
+
 /** Determine if a deployment is enabled (can ever be active) */
 inline bool DeploymentEnabled(const Consensus::Params& params, Consensus::BuriedDeployment dep)
 {
     assert(Consensus::ValidDeployment(dep));
     return params.DeploymentHeight(dep) != std::numeric_limits<int>::max();
 }
 
+inline bool DeploymentEnabled(const Consensus::Params& params, Consensus::DeploymentPos dep)
+{
+    assert(Consensus::ValidDeployment(dep));
+    return params.vDeployments[dep].nTimeout != 0;
+}
+
 #endif // BITCOIN_DEPLOYMENTSTATUS_H

src/node/interfaces.cpp

@@ -6,6 +6,7 @@
 #include <banman.h>
 #include <chain.h>
 #include <chainparams.h>
+#include <deploymentstatus.h>
 #include <external_signer.h>
 #include <init.h>
 #include <interfaces/chain.h>
@@ -692,7 +693,7 @@ class ChainImpl : public Chain
     {
         LOCK(::cs_main);
         const CBlockIndex* tip = Assert(m_node.chainman)->ActiveChain().Tip();
-        return VersionBitsState(tip, Params().GetConsensus(), Consensus::DEPLOYMENT_TAPROOT, versionbitscache) == ThresholdState::ACTIVE;
+        return DeploymentActiveAfter(tip, Params().GetConsensus(), Consensus::DEPLOYMENT_TAPROOT);
     }
     NodeContext& m_node;
 };

src/rpc/blockchain.cpp

@@ -12,6 +12,7 @@
 #include <coins.h>
 #include <consensus/validation.h>
 #include <core_io.h>
+#include <deploymentstatus.h>
 #include <hash.h>
 #include <index/blockfilterindex.h>
 #include <index/coinstatsindex.h>

src/test/versionbits_tests.cpp

@@ -5,6 +5,7 @@
 #include <chain.h>
 #include <chainparams.h>
 #include <consensus/params.h>
+#include <deploymentstatus.h>
 #include <test/util/setup_common.h>
 #include <validation.h>
 #include <versionbits.h>

src/validation.cpp

@@ -684,9 +684,8 @@ bool MemPoolAccept::PreChecks(ATMPArgs& args, Workspace& ws)
     }
 
     // Check for non-standard pay-to-script-hash in inputs
-    const auto& params = args.m_chainparams.GetConsensus();
-    auto taproot_state = VersionBitsState(m_active_chainstate.m_chain.Tip(), params, Consensus::DEPLOYMENT_TAPROOT, versionbitscache);
-    if (fRequireStandard && !AreInputsStandard(tx, m_view, taproot_state == ThresholdState::ACTIVE)) {
+    const bool taproot_active = DeploymentActiveAfter(m_active_chainstate.m_chain.Tip(), args.m_chainparams.GetConsensus(), Consensus::DEPLOYMENT_TAPROOT);
+    if (fRequireStandard && !AreInputsStandard(tx, m_view, taproot_active)) {
         return state.Invalid(TxValidationResult::TX_INPUTS_NOT_STANDARD, "bad-txns-nonstandard-inputs");
     }
 
@@ -1607,8 +1606,6 @@ void StopScriptCheckWorkerThreads()
     scriptcheckqueue.StopWorkerThreads();
 }
 
-VersionBitsCache versionbitscache;
-
 int32_t ComputeBlockVersion(const CBlockIndex* pindexPrev, const Consensus::Params& params)
 {
     int32_t nVersion = VERSIONBITS_TOP_BITS;
@@ -1687,8 +1684,8 @@ static unsigned int GetBlockScriptFlags(const CBlockIndex* pindex, const Consens
         flags |= SCRIPT_VERIFY_CHECKSEQUENCEVERIFY;
     }
 
-    // Start enforcing Taproot using versionbits logic.
-    if (VersionBitsState(pindex->pprev, consensusparams, Consensus::DEPLOYMENT_TAPROOT, versionbitscache) == ThresholdState::ACTIVE) {
+    // Enforce Taproot (BIP340-BIP342)
+    if (DeploymentActiveAt(*pindex, consensusparams, Consensus::DEPLOYMENT_TAPROOT)) {
         flags |= SCRIPT_VERIFY_TAPROOT;
     }
 

src/validation.h

@@ -24,7 +24,6 @@
 #include <sync.h>
 #include <txmempool.h> // For CTxMemPool::cs
 #include <txdb.h>
-#include <versionbits.h>
 #include <serialize.h>
 #include <util/check.h>
 #include <util/hasher.h>
@@ -1020,8 +1019,6 @@ class ChainstateManager
 /** Global variable that points to the active block tree (protected by cs_main) */
 extern std::unique_ptr<CBlockTreeDB> pblocktree;
 
-extern VersionBitsCache versionbitscache;
-
 /**
  * Determine what nVersion a new block should use.
  */