refactor: Enable BIP157 block filters only for masternodes

Instead of enabling peerblockfilters by default for all nodes, this change:
- Keeps DEFAULT_PEERBLOCKFILTERS as false (unchanged from current behavior)
- Automatically enables peerblockfilters and blockfilterindex for masternodes
- Allows masternodes to still explicitly disable with -peerblockfilters=0

This approach:
- Deploys block filters to the nodes that provide the majority of network services
- Avoids breaking changes for regular nodes
- Follows existing Dash patterns (like auto-disabling wallet for masternodes)
- Eliminates the need for extensive test suite modifications

The parameter interaction happens in InitParameterInteraction() where
masternodes (identified by -masternodeblsprivkey) automatically get:
- peerblockfilters=1
- blockfilterindex=basic

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: PastaPastaPasta

src/init.cpp

@@ -1018,8 +1018,17 @@ void InitParameterInteraction(ArgsManager& args)
         LogPrintf("%s: parameter interaction: additional indexes -> setting -checklevel=4\n", __func__);
     }
 
-    if (args.IsArgSet("-masternodeblsprivkey") && args.SoftSetBoolArg("-disablewallet", true)) {
-        LogPrintf("%s: parameter interaction: -masternodeblsprivkey set -> setting -disablewallet=1\n", __func__);
+    if (args.IsArgSet("-masternodeblsprivkey")) {
+        if (args.SoftSetBoolArg("-disablewallet", true)) {
+            LogPrintf("%s: parameter interaction: -masternodeblsprivkey set -> setting -disablewallet=1\n", __func__);
+        }
+        // Enable block filters for masternodes to improve network services
+        if (args.SoftSetBoolArg("-peerblockfilters", true)) {
+            LogPrintf("%s: parameter interaction: -masternodeblsprivkey set -> setting -peerblockfilters=1\n", __func__);
+        }
+        if (args.SoftSetArg("-blockfilterindex", "basic")) {
+            LogPrintf("%s: parameter interaction: -masternodeblsprivkey set -> setting -blockfilterindex=basic\n", __func__);
+        }
     }
 }
 

src/net_processing.h

@@ -33,7 +33,7 @@ static const unsigned int DEFAULT_MAX_ORPHAN_TRANSACTIONS_SIZE = 10; // this all
 /** Default number of orphan+recently-replaced txn to keep around for block reconstruction */
 static const unsigned int DEFAULT_BLOCK_RECONSTRUCTION_EXTRA_TXN = 100;
 static const bool DEFAULT_PEERBLOOMFILTERS = true;
-static const bool DEFAULT_PEERBLOCKFILTERS = true;
+static const bool DEFAULT_PEERBLOCKFILTERS = false;
 /** Threshold for marking a node to be discouraged, e.g. disconnected and added to the discouragement filter. */
 static const int DISCOURAGEMENT_THRESHOLD{100};
 

test/functional/feature_index_prune.py

@@ -22,7 +22,7 @@ def set_test_params(self):
         self.num_nodes = 4
         self.extra_args = [
             ["-fastprune", "-prune=1", "-blockfilterindex=1"] + DEPLOYMENT_ARGS,
-            ["-fastprune", "-prune=1", "-coinstatsindex=1", "-blockfilterindex=0", "-peerblockfilters=0"] + DEPLOYMENT_ARGS,
+            ["-fastprune", "-prune=1", "-coinstatsindex=1"] + DEPLOYMENT_ARGS,
             ["-fastprune", "-prune=1", "-blockfilterindex=1", "-coinstatsindex=1"] + DEPLOYMENT_ARGS,
             [] + DEPLOYMENT_ARGS,
         ]
@@ -54,7 +54,7 @@ def mine_batches(self, blocks):
 
     def restart_without_indices(self):
         for i in range(3):
-            self.restart_node(i, extra_args=["-fastprune", "-prune=1", "-blockfilterindex=0", "-coinstatsindex=0", "-peerblockfilters=0"] + DEPLOYMENT_ARGS, expected_stderr=EXPECTED_STDERR_NO_GOV_PRUNE)
+            self.restart_node(i, extra_args=["-fastprune", "-prune=1"] + DEPLOYMENT_ARGS, expected_stderr=EXPECTED_STDERR_NO_GOV_PRUNE)
         self.reconnect_nodes()
 
     def run_test(self):

test/functional/feature_reindex.py

@@ -25,7 +25,7 @@ def reindex(self, justchainstate=False, txindex=0):
         self.generatetoaddress(self.nodes[0], 3, self.nodes[0].get_deterministic_priv_key().address)
         blockcount = self.nodes[0].getblockcount()
         self.stop_nodes()
-        extra_args = [["-reindex-chainstate", "-txindex=0", "-blockfilterindex=0"]] if justchainstate else [["-reindex", f"-txindex={txindex}"]]
+        extra_args = [["-reindex-chainstate", "-txindex=0"]] if justchainstate else [["-reindex", f"-txindex={txindex}"]]
         self.start_nodes(extra_args)
         assert_equal(self.nodes[0].getblockcount(), blockcount)  # start_node is blocking on reindex
         self.log.info("Success")

test/functional/feature_unsupported_utxo_db.py

@@ -53,7 +53,7 @@ def run_test(self):
         )
 
         self.log.info("Drop legacy utxo db")
-        self.start_node(1, extra_args=["-reindex-chainstate", "-txindex=0", "-blockfilterindex=0"])
+        self.start_node(1, extra_args=["-reindex-chainstate", "-txindex=0"])
         assert_equal(self.nodes[1].getbestblockhash(), block)
         assert_equal(self.nodes[1].gettxoutsetinfo()["total_amount"], 500)
 

test/functional/p2p_blockfilters.py

@@ -47,7 +47,7 @@ def set_test_params(self):
         self.num_nodes = 2
         self.extra_args = [
             ["-blockfilterindex", "-peerblockfilters"],
-            ["-blockfilterindex", "-peerblockfilters=0"],
+            ["-blockfilterindex"],
         ]
 
     def run_test(self):
@@ -264,7 +264,7 @@ def run_test(self):
 
         self.log.info("Test -peerblockfilters without -blockfilterindex raises an error")
         self.stop_node(0)
-        self.nodes[0].extra_args = ["-peerblockfilters", "-blockfilterindex=0"]
+        self.nodes[0].extra_args = ["-peerblockfilters"]
         msg = "Error: Cannot set -peerblockfilters without -blockfilterindex."
         self.nodes[0].assert_start_raises_init_error(expected_msg=msg)