Merge #18910: p2p: add MAX_FEELER_CONNECTIONS constant

e3047ed test: use p2p constants in denial of service tests (fanquake)
25d8264 p2p: add MAX_FEELER_CONNECTIONS constant (tryphe)

Pull request description:

  Extracted from #16003.

ACKs for top commit:
  naumenkogs:
    utACK e3047ed

Tree-SHA512: 14fc15292be4db2e825a0331dd189a48713464f622a91c589122c1a7135bcfd37a61e64af1e76d32880ded09c24efd54d3c823467d6c35367a380e0be33bd35f

Author: fanquake

src/init.cpp

@@ -1887,7 +1887,7 @@ bool AppInitMain(NodeContext& node)
     connOptions.m_max_outbound_full_relay = std::min(MAX_OUTBOUND_FULL_RELAY_CONNECTIONS, connOptions.nMaxConnections);
     connOptions.m_max_outbound_block_relay = std::min(MAX_BLOCKS_ONLY_CONNECTIONS, connOptions.nMaxConnections-connOptions.m_max_outbound_full_relay);
     connOptions.nMaxAddnode = MAX_ADDNODE_CONNECTIONS;
-    connOptions.nMaxFeeler = 1;
+    connOptions.nMaxFeeler = MAX_FEELER_CONNECTIONS;
     connOptions.nBestHeight = chain_active_height;
     connOptions.uiInterface = &uiInterface;
     connOptions.m_banman = node.banman.get();

src/net.h

@@ -62,6 +62,8 @@ static const int MAX_OUTBOUND_FULL_RELAY_CONNECTIONS = 8;
 static const int MAX_ADDNODE_CONNECTIONS = 8;
 /** Maximum number of block-relay-only outgoing connections */
 static const int MAX_BLOCKS_ONLY_CONNECTIONS = 2;
+/** Maximum number of feeler connections */
+static const int MAX_FEELER_CONNECTIONS = 1;
 /** -listen default */
 static const bool DEFAULT_LISTEN = true;
 /** -upnp default */

src/test/denialofservice_tests.cpp

@@ -151,11 +151,11 @@ BOOST_AUTO_TEST_CASE(stale_tip_peer_management)
     auto peerLogic = MakeUnique<PeerLogicValidation>(connman.get(), nullptr, *m_node.scheduler, *m_node.mempool);
 
     const Consensus::Params& consensusParams = Params().GetConsensus();
-    constexpr int max_outbound_full_relay = 8;
+    constexpr int max_outbound_full_relay = MAX_OUTBOUND_FULL_RELAY_CONNECTIONS;
     CConnman::Options options;
-    options.nMaxConnections = 125;
+    options.nMaxConnections = DEFAULT_MAX_PEER_CONNECTIONS;
     options.m_max_outbound_full_relay = max_outbound_full_relay;
-    options.nMaxFeeler = 1;
+    options.nMaxFeeler = MAX_FEELER_CONNECTIONS;
 
     connman->Init(options);
     std::vector<CNode *> vNodes;