feat: enable bip157 filters by default

doc/release-notes-6711.md

@@ -0,0 +1,6 @@
+Updated settings
+----------------
+
+- BIP157 compact block filters are now enabled by default. This improves privacy for light clients
+  and enables better support for pruned nodes. The `-blockfilterindex` option now defaults to `basic`
+  instead of `0` (disabled), and the `-peerblockfilters` option now defaults to `true` instead of `false` (#6711).

src/init.cpp

@@ -1132,7 +1132,11 @@ bool AppInitParameterInteraction(const ArgsManager& args)
     if (blockfilterindex_value == "" || blockfilterindex_value == "1") {
         g_enabled_filter_types = AllBlockFilterTypes();
     } else if (blockfilterindex_value != "0") {
-        const std::vector<std::string> names = args.GetArgs("-blockfilterindex");
+        std::vector<std::string> names = args.GetArgs("-blockfilterindex");
+        if (names.empty()) {
+            // Use default value when no explicit -blockfilterindex was provided
+            names.push_back(DEFAULT_BLOCKFILTERINDEX);
+        }
         for (const auto& name : names) {
             BlockFilterType filter_type;
             if (!BlockFilterTypeByName(name, filter_type)) {

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 = false;
+static const bool DEFAULT_PEERBLOCKFILTERS = true;
 /** Threshold for marking a node to be discouraged, e.g. disconnected and added to the discouragement filter. */
 static const int DISCOURAGEMENT_THRESHOLD{100};
 

src/validation.h

@@ -77,7 +77,7 @@ static const int64_t DEFAULT_MAX_TIP_AGE = 6 * 60 * 60; // ~144 blocks behind ->
 static const bool DEFAULT_CHECKPOINTS_ENABLED = true;
 static const bool DEFAULT_TXINDEX = true;
 static constexpr bool DEFAULT_COINSTATSINDEX{false};
-static const char* const DEFAULT_BLOCKFILTERINDEX = "0";
+static const char* const DEFAULT_BLOCKFILTERINDEX = "basic";
 /** Default for -persistmempool */
 static const bool DEFAULT_PERSIST_MEMPOOL = true;
 /** Default for -syncmempool */