Add maxscriptsize policy option

Author: luke-jr

src/init.cpp

@@ -651,6 +651,7 @@ void SetupServerArgs(ArgsManager& argsman)
                    strprintf("Maximum size of data in data carrier transactions we relay and mine, in bytes (default: %u)",
                              MAX_OP_RETURN_RELAY),
                    ArgsManager::ALLOW_ANY, OptionsCategory::NODE_RELAY);
+    argsman.AddArg("-maxscriptsize", strprintf("Maximum size of scripts we relay and mine (default: %s)", DEFAULT_SCRIPT_SIZE_POLICY_LIMIT), ArgsManager::ALLOW_ANY, OptionsCategory::NODE_RELAY);
     argsman.AddArg("-mempoolfullrbf", strprintf("Accept transaction replace-by-fee without requiring replaceability signaling (default: %u)", (DEFAULT_MEMPOOL_RBF_POLICY == RBFPolicy::Always)), ArgsManager::ALLOW_ANY, OptionsCategory::NODE_RELAY);
     argsman.AddArg("-mempoolreplacement", strprintf("Set to 0 to disable RBF entirely, \"fee,optin\" to honour RBF opt-out signal, or \"fee,-optin\" to always RBF aka full RBF (default: %s)", "fee,-optin"), ArgsManager::ALLOW_ANY, OptionsCategory::NODE_RELAY);
     argsman.AddArg("-mempooltruc", strprintf("Behaviour for transactions requesting TRUC limits: \"reject\" the transactions entirely, \"accept\" them just like any other, or \"enforce\" to impose their requested restrictions (default: %s)", "enforce"), ArgsManager::ALLOW_ANY, OptionsCategory::NODE_RELAY);
@@ -1045,6 +1046,8 @@ bool AppInitParameterInteraction(const ArgsManager& args)
         g_weight_per_data_byte = ((*parsed * WITNESS_SCALE_FACTOR) + 99) / 100;
     }
 
+    g_script_size_policy_limit = args.GetIntArg("-maxscriptsize", g_script_size_policy_limit);
+
     nBytesPerSigOp = args.GetIntArg("-bytespersigop", nBytesPerSigOp);
     nBytesPerSigOpStrict = args.GetIntArg("-bytespersigopstrict", nBytesPerSigOpStrict);
 

src/policy/policy.cpp

@@ -13,6 +13,7 @@
 #include <consensus/validation.h>
 #include <kernel/mempool_options.h>
 #include <policy/feerate.h>
+#include <policy/settings.h>
 #include <primitives/transaction.h>
 #include <script/interpreter.h>
 #include <script/script.h>
@@ -24,6 +25,8 @@
 #include <cstddef>
 #include <vector>
 
+unsigned int g_script_size_policy_limit{DEFAULT_SCRIPT_SIZE_POLICY_LIMIT};
+
 CAmount GetDustThreshold(const CTxOut& txout, const CFeeRate& dustRelayFeeIn)
 {
     // "Dust" is defined in terms of dustRelayFee,
@@ -138,7 +141,7 @@ bool IsStandardTx(const CTransaction& tx, const kernel::MemPoolOptions& opts, st
         // some minor future-proofing. That's also enough to spend a
         // 20-of-20 CHECKMULTISIG scriptPubKey, though such a scriptPubKey
         // is not considered standard.
-        if (txin.scriptSig.size() > MAX_STANDARD_SCRIPTSIG_SIZE) {
+        if (txin.scriptSig.size() > std::min(MAX_STANDARD_SCRIPTSIG_SIZE, g_script_size_policy_limit)) {
             MaybeReject("scriptsig-size");
         }
         if (!txin.scriptSig.IsPushOnly()) {
@@ -149,6 +152,10 @@ bool IsStandardTx(const CTransaction& tx, const kernel::MemPoolOptions& opts, st
     unsigned int nDataOut = 0;
     TxoutType whichType;
     for (const CTxOut& txout : tx.vout) {
+        if (txout.scriptPubKey.size() > g_script_size_policy_limit) {
+            MaybeReject("scriptpubkey-size");
+        }
+
         if (!::IsStandard(txout.scriptPubKey, opts.max_datacarrier_bytes, whichType)) {
             if (whichType == TxoutType::WITNESS_UNKNOWN) {
                 MaybeReject("scriptpubkey-unknown-witnessversion");
@@ -207,6 +214,10 @@ bool AreInputsStandard(const CTransaction& tx, const CCoinsViewCache& mapInputs,
     for (unsigned int i = 0; i < tx.vin.size(); i++) {
         const CTxOut& prev = mapInputs.AccessCoin(tx.vin[i].prevout).out;
 
+        if (prev.scriptPubKey.size() > g_script_size_policy_limit) {
+            MaybeReject("script-size");
+        }
+
         std::vector<std::vector<unsigned char> > vSolutions;
         TxoutType whichType = Solver(prev.scriptPubKey, vSolutions);
         if (whichType == TxoutType::NONSTANDARD) {
@@ -239,6 +250,9 @@ bool AreInputsStandard(const CTransaction& tx, const CCoinsViewCache& mapInputs,
                 return false;
             }
             CScript subscript(stack.back().begin(), stack.back().end());
+            if (subscript.size() > g_script_size_policy_limit) {
+                MaybeReject("scriptcheck-size");
+            }
             if (subscript.GetSigOpCount(true) > MAX_P2SH_SIGOPS) {
                 MaybeReject("scriptcheck-sigops");
             }
@@ -302,7 +316,7 @@ bool IsWitnessStandard(const CTransaction& tx, const CCoinsViewCache& mapInputs,
 
         // Check P2WSH standard limits
         if (witnessversion == 0 && witnessprogram.size() == WITNESS_V0_SCRIPTHASH_SIZE) {
-            if (tx.vin[i].scriptWitness.stack.back().size() > MAX_STANDARD_P2WSH_SCRIPT_SIZE)
+            if (tx.vin[i].scriptWitness.stack.back().size() > std::min(MAX_STANDARD_P2WSH_SCRIPT_SIZE, g_script_size_policy_limit))
                 MaybeReject("script-size");
             size_t sizeWitnessStack = tx.vin[i].scriptWitness.stack.size() - 1;
             if (sizeWitnessStack > MAX_STANDARD_P2WSH_STACK_ITEMS)
@@ -328,12 +342,15 @@ bool IsWitnessStandard(const CTransaction& tx, const CCoinsViewCache& mapInputs,
             if (stack.size() >= 2) {
                 // Script path spend (2 or more stack elements after removing optional annex)
                 const auto& control_block = SpanPopBack(stack);
-                SpanPopBack(stack); // Ignore script
+                const auto& tapscript = SpanPopBack(stack);
                 if (control_block.empty()) {
                     // Empty control block is invalid
                     out_reason = reason_prefix + "taproot-control-missing";
                     return false;
                 }
+                if (tapscript.size() > g_script_size_policy_limit) {
+                    MaybeReject("script-size");
+                }
                 if ((control_block[0] & TAPROOT_LEAF_MASK) == TAPROOT_LEAF_TAPSCRIPT) {
                     // Leaf version 0xc0 (aka Tapscript, see BIP 342)
                     if (!ignore_rejects.count(reason_prefix + "taproot-stackitem-size")) {

src/policy/policy.h

@@ -44,6 +44,8 @@ static constexpr unsigned int MAX_P2SH_SIGOPS{15};
 static constexpr unsigned int MAX_STANDARD_TX_SIGOPS_COST{MAX_BLOCK_SIGOPS_COST/5};
 /** Default for -incrementalrelayfee, which sets the minimum feerate increase for mempool limiting or replacement **/
 static constexpr unsigned int DEFAULT_INCREMENTAL_RELAY_FEE{1000};
+/** Default for -maxscriptsize */
+static constexpr unsigned int DEFAULT_SCRIPT_SIZE_POLICY_LIMIT{std::numeric_limits<unsigned int>::max()};
 /** Default for -bytespersigop */
 static constexpr unsigned int DEFAULT_BYTES_PER_SIGOP{20};
 /** Default for -bytespersigopstrict */

src/policy/settings.h

@@ -6,6 +6,7 @@
 #ifndef BITCOIN_POLICY_SETTINGS_H
 #define BITCOIN_POLICY_SETTINGS_H
 
+extern unsigned int g_script_size_policy_limit;
 extern unsigned int nBytesPerSigOp;
 extern unsigned int nBytesPerSigOpStrict;
 extern unsigned int g_weight_per_data_byte;