add -rejectparasites option

Github-Pull: knots#78
Rebased-From: 18cd7b0

Author: Retropex

src/init.cpp

@@ -664,6 +664,7 @@ void SetupServerArgs(ArgsManager& argsman)
                    OptionsCategory::NODE_RELAY);
     argsman.AddArg("-minrelaytxfee=<amt>", strprintf("Fees (in %s/kvB) smaller than this are considered zero fee for relaying, mining and transaction creation (default: %s)",
         CURRENCY_UNIT, FormatMoney(DEFAULT_MIN_RELAY_TX_FEE)), ArgsManager::ALLOW_ANY, OptionsCategory::NODE_RELAY);
+    argsman.AddArg("-rejectparasites", strprintf("Refuse to relay or mine parasitic overlay protocols (default: %u)", DEFAULT_REJECT_PARASITES), ArgsManager::ALLOW_ANY, OptionsCategory::NODE_RELAY);
     argsman.AddArg("-rejecttokens",
                    strprintf("Refuse to relay or mine transactions involving non-bitcoin tokens (default: %u)",
                              DEFAULT_REJECT_TOKENS),

src/kernel/mempool_options.h

@@ -63,6 +63,7 @@ struct MemPoolOptions {
     bool datacarrier_fullcount{DEFAULT_DATACARRIER_FULLCOUNT};
     bool permit_bare_pubkey{DEFAULT_PERMIT_BAREPUBKEY};
     bool permit_bare_multisig{DEFAULT_PERMIT_BAREMULTISIG};
+    bool reject_parasites{DEFAULT_REJECT_PARASITES};
     bool reject_tokens{DEFAULT_REJECT_TOKENS};
     bool accept_non_std_datacarrier{DEFAULT_ACCEPT_NON_STD_DATACARRIER};
     bool require_standard{true};

src/node/mempool_args.cpp

@@ -85,6 +85,8 @@ util::Result<void> ApplyArgsManOptions(const ArgsManager& argsman, const CChainP
 
     mempool_opts.permit_bare_multisig = argsman.GetBoolArg("-permitbaremultisig", DEFAULT_PERMIT_BAREMULTISIG);
 
+    mempool_opts.reject_parasites = argsman.GetBoolArg("-rejectparasites", DEFAULT_REJECT_PARASITES);
+
     mempool_opts.reject_tokens = argsman.GetBoolArg("-rejecttokens", DEFAULT_REJECT_TOKENS);
 
     if (argsman.GetBoolArg("-datacarrier", DEFAULT_ACCEPT_DATACARRIER)) {

src/policy/policy.cpp

@@ -129,6 +129,10 @@ bool IsStandardTx(const CTransaction& tx, const kernel::MemPoolOptions& opts, st
         MaybeReject("tx-size");
     }
 
+    if (tx.nLockTime == 21 && opts.reject_parasites) {
+        MaybeReject("parasite-cat21");
+    }
+
     for (const CTxIn& txin : tx.vin)
     {
         // Biggest 'standard' txin involving only keys is a 15-of-15 P2SH

src/policy/policy.h

@@ -56,6 +56,8 @@ static constexpr bool DEFAULT_REJECT_TOKENS{false};
 static constexpr bool DEFAULT_PERMIT_BAREPUBKEY{true};
 /** Default for -permitbaremultisig */
 static constexpr bool DEFAULT_PERMIT_BAREMULTISIG{true};
+/** Default for -rejectparasites */
+static constexpr bool DEFAULT_REJECT_PARASITES{false};
 /** The maximum number of witness stack items in a standard P2WSH script */
 static constexpr unsigned int MAX_STANDARD_P2WSH_STACK_ITEMS{100};
 /** The maximum size in bytes of each witness stack item in a standard P2WSH script */