31.x: Implement BIP 54 (Consensus Cleanup) without mainnet activation

src/CMakeLists.txt

@@ -106,6 +106,7 @@ add_library(bitcoin_common STATIC EXCLUDE_FROM_ALL
   common/system.cpp
   common/url.cpp
   compressor.cpp
+  consensus/tx_verify.cpp
   core_io.cpp
   deploymentinfo.cpp
   external_signer.cpp
@@ -181,7 +182,6 @@ add_library(bitcoin_node STATIC EXCLUDE_FROM_ALL
   bip324.cpp
   blockencodings.cpp
   blockfilter.cpp
-  consensus/tx_verify.cpp
   dbwrapper.cpp
   deploymentstatus.cpp
   flatfile.cpp

src/chainparams.cpp

@@ -23,29 +23,8 @@
 
 using util::SplitString;
 
-void ReadSigNetArgs(const ArgsManager& args, CChainParams::SigNetOptions& options)
-{
-    if (!args.GetArgs("-signetseednode").empty()) {
-        options.seeds.emplace(args.GetArgs("-signetseednode"));
-    }
-    if (!args.GetArgs("-signetchallenge").empty()) {
-        const auto signet_challenge = args.GetArgs("-signetchallenge");
-        if (signet_challenge.size() != 1) {
-            throw std::runtime_error("-signetchallenge cannot be multiple values.");
-        }
-        const auto val{TryParseHex<uint8_t>(signet_challenge[0])};
-        if (!val) {
-            throw std::runtime_error(strprintf("-signetchallenge must be hex, not '%s'.", signet_challenge[0]));
-        }
-        options.challenge.emplace(*val);
-    }
-}
-
-void ReadRegTestArgs(const ArgsManager& args, CChainParams::RegTestOptions& options)
+static void HandleDeploymentArgs(const ArgsManager& args, CChainParams::DeploymentOptions& options)
 {
-    if (auto value = args.GetBoolArg("-fastprune")) options.fastprune = *value;
-    if (HasTestOption(args, "bip94")) options.enforce_bip94 = true;
-
     for (const std::string& arg : args.GetArgs("-testactivationheight")) {
         const auto found{arg.find('@')};
         if (found == std::string::npos) {
@@ -107,6 +86,43 @@ void ReadRegTestArgs(const ArgsManager& args, CChainParams::RegTestOptions& opti
     }
 }
 
+void ReadMainNetArgs(const ArgsManager& args, CChainParams::MainNetOptions& options)
+{
+    HandleDeploymentArgs(args, options.dep_opts);
+}
+
+void ReadTestNetArgs(const ArgsManager& args, CChainParams::TestNetOptions& options)
+{
+    HandleDeploymentArgs(args, options.dep_opts);
+}
+
+void ReadSigNetArgs(const ArgsManager& args, CChainParams::SigNetOptions& options)
+{
+    if (!args.GetArgs("-signetseednode").empty()) {
+        options.seeds.emplace(args.GetArgs("-signetseednode"));
+    }
+    if (!args.GetArgs("-signetchallenge").empty()) {
+        const auto signet_challenge = args.GetArgs("-signetchallenge");
+        if (signet_challenge.size() != 1) {
+            throw std::runtime_error("-signetchallenge cannot be multiple values.");
+        }
+        const auto val{TryParseHex<uint8_t>(signet_challenge[0])};
+        if (!val) {
+            throw std::runtime_error(strprintf("-signetchallenge must be hex, not '%s'.", signet_challenge[0]));
+        }
+        options.challenge.emplace(*val);
+    }
+    HandleDeploymentArgs(args, options.dep_opts);
+}
+
+void ReadRegTestArgs(const ArgsManager& args, CChainParams::RegTestOptions& options)
+{
+    if (auto value = args.GetBoolArg("-fastprune")) options.fastprune = *value;
+    if (HasTestOption(args, "bip94")) options.enforce_bip94 = true;
+
+    HandleDeploymentArgs(args, options.dep_opts);
+}
+
 static std::unique_ptr<const CChainParams> globalChainParams;
 
 const CChainParams &Params() {
@@ -117,12 +133,21 @@ const CChainParams &Params() {
 std::unique_ptr<const CChainParams> CreateChainParams(const ArgsManager& args, const ChainType chain)
 {
     switch (chain) {
-    case ChainType::MAIN:
-        return CChainParams::Main();
-    case ChainType::TESTNET:
-        return CChainParams::TestNet();
-    case ChainType::TESTNET4:
-        return CChainParams::TestNet4();
+    case ChainType::MAIN: {
+        auto opts = CChainParams::MainNetOptions{};
+        ReadMainNetArgs(args, opts);
+        return CChainParams::Main(opts);
+    }
+    case ChainType::TESTNET: {
+        auto opts = CChainParams::TestNetOptions{};
+        ReadTestNetArgs(args, opts);
+        return CChainParams::TestNet(opts);
+    }
+    case ChainType::TESTNET4: {
+        auto opts = CChainParams::TestNetOptions{};
+        ReadTestNetArgs(args, opts);
+        return CChainParams::TestNet4(opts);
+    }
     case ChainType::SIGNET: {
         auto opts = CChainParams::SigNetOptions{};
         ReadSigNetArgs(args, opts);

src/chainparamsbase.cpp

@@ -16,10 +16,10 @@ void SetupChainParamsBaseOptions(ArgsManager& argsman)
     argsman.AddArg("-chain=<chain>", "Use the chain <chain> (default: main). Allowed values: " LIST_CHAIN_NAMES, ArgsManager::ALLOW_ANY, OptionsCategory::CHAINPARAMS);
     argsman.AddArg("-regtest", "Enter regression test mode, which uses a special chain in which blocks can be solved instantly. "
                  "This is intended for regression testing tools and app development. Equivalent to -chain=regtest.", ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::CHAINPARAMS);
-    argsman.AddArg("-testactivationheight=name@height.", "Set the activation height of 'name' (segwit, bip34, dersig, cltv, csv). (regtest-only)", ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::DEBUG_TEST);
+    argsman.AddArg("-testactivationheight=name@height.", "Set the activation height of 'name' (segwit, bip34, dersig, cltv, csv). (test-only)", ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::DEBUG_TEST);
     argsman.AddArg("-testnet", "Use the testnet3 chain. Equivalent to -chain=test. Support for testnet3 is deprecated and will be removed in an upcoming release. Consider moving to testnet4 now by using -testnet4.", ArgsManager::ALLOW_ANY, OptionsCategory::CHAINPARAMS);
     argsman.AddArg("-testnet4", "Use the testnet4 chain. Equivalent to -chain=testnet4.", ArgsManager::ALLOW_ANY, OptionsCategory::CHAINPARAMS);
-    argsman.AddArg("-vbparams=deployment:start:end[:min_activation_height]", "Use given start/end times and min_activation_height for specified version bits deployment (regtest-only)", ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::CHAINPARAMS);
+    argsman.AddArg("-vbparams=deployment:start:end[:min_activation_height]", "Use given start/end times and min_activation_height for specified version bits deployment (test-only)", ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::CHAINPARAMS);
     argsman.AddArg("-signet", "Use the signet chain. Equivalent to -chain=signet. Note that the network is defined by the -signetchallenge parameter", ArgsManager::ALLOW_ANY, OptionsCategory::CHAINPARAMS);
     argsman.AddArg("-signetchallenge", "Blocks must satisfy the given script to be considered valid (only for signet networks; defaults to the global default signet test network challenge)", ArgsManager::ALLOW_ANY | ArgsManager::DISALLOW_NEGATION, OptionsCategory::CHAINPARAMS);
     argsman.AddArg("-signetseednode", "Specify a seed node for the signet network, in the hostname[:port] format, e.g. sig.net:1234 (may be used multiple times to specify multiple seed nodes; defaults to the global default signet test network seed node(s))", ArgsManager::ALLOW_ANY | ArgsManager::DISALLOW_NEGATION, OptionsCategory::CHAINPARAMS);

src/consensus/consensus.h

@@ -27,11 +27,26 @@ static const size_t MIN_SERIALIZABLE_TRANSACTION_WEIGHT = WITNESS_SCALE_FACTOR *
 /** Interpret sequence numbers as relative lock-time constraints. */
 static constexpr unsigned int LOCKTIME_VERIFY_SEQUENCE = (1 << 0);
 
+/**
+ * Under BIP54, the first block in a difficulty adjustment period must not be more than 2
+ * hours (7200 seconds) earlier than the last block of the previous period.
+ */
+static constexpr int64_t MAX_TIMEWARP_BIP54{2 * 60 * 60};
+
 /**
  * Maximum number of seconds that the timestamp of the first
  * block of a difficulty adjustment period is allowed to
  * be earlier than the last block of the previous period (BIP94).
  */
-static constexpr int64_t MAX_TIMEWARP = 600;
+static constexpr int64_t MAX_TIMEWARP_TESTNET4 = 600;
+
+/** The maximum number of potentially executed legacy signature operations in a single tx */
+static constexpr unsigned int MAX_TX_BIP54_SIGOPS{2'500};
+
+/**
+ * 64-byte transactions are invalid (BIP 54) due to serious flaws in the Merkle tree algorithm
+ * that make it so that such transactions may be re-interpreted as inner tree nodes.
+ */
+static constexpr unsigned int INVALID_TX_NONWITNESS_SIZE{64};
 
 #endif // BITCOIN_CONSENSUS_CONSENSUS_H

src/consensus/params.h

@@ -34,6 +34,7 @@ constexpr bool ValidDeployment(BuriedDeployment dep) { return dep <= DEPLOYMENT_
 enum DeploymentPos : uint16_t {
     DEPLOYMENT_TESTDUMMY,
     DEPLOYMENT_TAPROOT, // Deployment of Schnorr/Taproot (BIPs 340-342)
+    DEPLOYMENT_CONSENSUSCLEANUP, // Deployment of BIP 54
     // NOTE: Also add new deployments to VersionBitsDeploymentInfo in deploymentinfo.cpp
     MAX_VERSION_BITS_DEPLOYMENTS
 };

src/consensus/tx_verify.cpp

@@ -161,14 +161,44 @@ int64_t GetTransactionSigOpCost(const CTransaction& tx, const CCoinsViewCache& i
     return nSigOps;
 }
 
-bool Consensus::CheckTxInputs(const CTransaction& tx, TxValidationState& state, const CCoinsViewCache& inputs, int nSpendHeight, CAmount& txfee)
+bool Consensus::CheckSigopsBIP54(const CTransaction& tx, const CCoinsViewCache& inputs)
+{
+    Assert(!tx.IsCoinBase());
+
+    unsigned int sigops{0};
+    for (const auto& txin: tx.vin) {
+        const auto& prev_txo{inputs.AccessCoin(txin.prevout).out};
+
+        // Unlike the existing block wide sigop limit which counts sigops present in the block
+        // itself (including the scriptPubKey which is not executed until spending later), BIP54
+        // counts sigops in the block where they are potentially executed (only).
+        // This means sigops in the spent scriptPubKey count toward the limit.
+        // `fAccurate` means correctly accounting sigops for CHECKMULTISIGs(VERIFY) with 16 pubkeys
+        // or fewer. This method of accounting was introduced by BIP16, and BIP54 reuses it.
+        // The GetSigOpCount call on the previous scriptPubKey counts both bare and P2SH sigops.
+        sigops += txin.scriptSig.GetSigOpCount(/*fAccurate=*/true);
+        sigops += prev_txo.scriptPubKey.GetSigOpCount(txin.scriptSig);
+
+        if (sigops > MAX_TX_BIP54_SIGOPS) {
+            return false;
+        }
+    }
+
+    return true;
+}
+
+bool Consensus::CheckTxInputs(const CTransaction& tx, TxValidationState& state, const CCoinsViewCache& inputs, int nSpendHeight, CAmount& txfee, bool enforce_bip54)
 {
     // are the actual inputs available?
     if (!inputs.HaveInputs(tx)) {
         return state.Invalid(TxValidationResult::TX_MISSING_INPUTS, "bad-txns-inputs-missingorspent",
                          strprintf("%s: inputs missing/spent", __func__));
     }
 
+    if (enforce_bip54 && !Consensus::CheckSigopsBIP54(tx, inputs)) {
+        return state.Invalid(TxValidationResult::TX_CONSENSUS, "bad-txns-legacy-sigops", "too many legacy sigops (BIP54)");
+    }
+
     CAmount nValueIn = 0;
     for (unsigned int i = 0; i < tx.vin.size(); ++i) {
         const COutPoint &prevout = tx.vin[i].prevout;

src/consensus/tx_verify.h

@@ -19,13 +19,19 @@ class TxValidationState;
 /** Transaction validation functions */
 
 namespace Consensus {
+/**
+ * Check the total number of non-witness sigops across the whole transaction, as per BIP54.
+ */
+bool CheckSigopsBIP54(const CTransaction& tx, const CCoinsViewCache& inputs);
+
 /**
  * Check whether all inputs of this transaction are valid (no double spends and amounts)
  * This does not modify the UTXO set. This does not check scripts and sigs.
  * @param[out] txfee Set to the transaction fee if successful.
+ * @param[in] enforce_bip54 Whether to perform the BIP54 sigops check.
  * Preconditions: tx.IsCoinBase() is false.
  */
-[[nodiscard]] bool CheckTxInputs(const CTransaction& tx, TxValidationState& state, const CCoinsViewCache& inputs, int nSpendHeight, CAmount& txfee);
+[[nodiscard]] bool CheckTxInputs(const CTransaction& tx, TxValidationState& state, const CCoinsViewCache& inputs, int nSpendHeight, CAmount& txfee, bool enforce_bip54);
 } // namespace Consensus
 
 /** Auxiliary functions for transaction validation (ideally should not be exposed) */

src/deploymentinfo.cpp

@@ -17,6 +17,10 @@ const std::array<VBDeploymentInfo,Consensus::MAX_VERSION_BITS_DEPLOYMENTS> Versi
         .name = "taproot",
         .gbt_optional_rule = true,
     },
+    VBDeploymentInfo{
+        .name = "consensuscleanup",
+        .gbt_optional_rule = false,
+    },
 };
 
 std::string DeploymentName(Consensus::BuriedDeployment dep)

src/init.cpp

@@ -1120,6 +1120,16 @@ bool AppInitParameterInteraction(const ArgsManager& args)
         }
     }
 
+    // Prevent setting deployment parameters on mainnet.
+    if (chainparams.GetChainType() == ChainType::MAIN) {
+        if (args.IsArgSet("-testactivationheight")) {
+            return InitError(_("The -testactivationheight option may not be used on mainnet."));
+        }
+        if (args.IsArgSet("-vbparams")) {
+            return InitError(_("The -vbparams option may not be used on mainnet."));
+        }
+    }
+
     // Also report errors from parsing before daemonization
     {
         kernel::Notifications notifications{};

src/kernel/bitcoinkernel.cpp

@@ -799,10 +799,10 @@ btck_ChainParameters* btck_chain_parameters_create(const btck_ChainType chain_ty
         return btck_ChainParameters::ref(const_cast<CChainParams*>(CChainParams::TestNet4().release()));
     }
     case btck_ChainType_SIGNET: {
-        return btck_ChainParameters::ref(const_cast<CChainParams*>(CChainParams::SigNet({}).release()));
+        return btck_ChainParameters::ref(const_cast<CChainParams*>(CChainParams::SigNet().release()));
     }
     case btck_ChainType_REGTEST: {
-        return btck_ChainParameters::ref(const_cast<CChainParams*>(CChainParams::RegTest({}).release()));
+        return btck_ChainParameters::ref(const_cast<CChainParams*>(CChainParams::RegTest().release()));
     }
     }
     assert(false);