p2p: adaptive connections services flags

src/Makefile.test.include

@@ -117,6 +117,7 @@ BITCOIN_TESTS =\
   test/net_tests.cpp \
   test/netbase_tests.cpp \
   test/orphanage_tests.cpp \
+  test/peerman_tests.cpp \
   test/pmt_tests.cpp \
   test/policy_fee_tests.cpp \
   test/policyestimator_tests.cpp \

src/test/peerman_tests.cpp

@@ -0,0 +1,76 @@
+// Copyright (c) 2024-present The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or https://www.opensource.org/licenses/mit-license.php.
+
+#include <chainparams.h>
+#include <node/miner.h>
+#include <net_processing.h>
+#include <pow.h>
+#include <test/util/setup_common.h>
+#include <validation.h>
+
+#include <boost/test/unit_test.hpp>
+
+BOOST_FIXTURE_TEST_SUITE(peerman_tests, RegTestingSetup)
+
+/** Window, in blocks, for connecting to NODE_NETWORK_LIMITED peers */
+static constexpr int64_t NODE_NETWORK_LIMITED_ALLOW_CONN_BLOCKS = 144;
+
+static void mineBlock(const node::NodeContext& node, std::chrono::seconds block_time)
+{
+    auto curr_time = GetTime<std::chrono::seconds>();
+    SetMockTime(block_time); // update time so the block is created with it
+    CBlock block = node::BlockAssembler{node.chainman->ActiveChainstate(), nullptr}.CreateNewBlock(CScript() << OP_TRUE)->block;
+    while (!CheckProofOfWork(block.GetHash(), block.nBits, node.chainman->GetConsensus())) ++block.nNonce;
+    block.fChecked = true; // little speedup
+    SetMockTime(curr_time); // process block at current time
+    Assert(node.chainman->ProcessNewBlock(std::make_shared<const CBlock>(block), /*force_processing=*/true, /*min_pow_checked=*/true, nullptr));
+    SyncWithValidationInterfaceQueue(); // drain events queue
+}
+
+// Verifying when network-limited peer connections are desirable based on the node's proximity to the tip
+BOOST_AUTO_TEST_CASE(connections_desirable_service_flags)
+{
+    std::unique_ptr<PeerManager> peerman = PeerManager::make(*m_node.connman, *m_node.addrman, nullptr, *m_node.chainman, *m_node.mempool, {});
+    auto consensus = m_node.chainman->GetParams().GetConsensus();
+
+    // Check we start connecting to full nodes
+    ServiceFlags peer_flags{NODE_WITNESS | NODE_NETWORK_LIMITED};
+    BOOST_CHECK(peerman->GetDesirableServiceFlags(peer_flags) == ServiceFlags(NODE_NETWORK | NODE_WITNESS));
+
+    // Make peerman aware of the initial best block and verify we accept limited peers when we start close to the tip time.
+    auto tip = WITH_LOCK(::cs_main, return m_node.chainman->ActiveChain().Tip());
+    uint64_t tip_block_time = tip->GetBlockTime();
+    int tip_block_height = tip->nHeight;
+    peerman->SetBestBlock(tip_block_height, std::chrono::seconds{tip_block_time});
+
+    SetMockTime(tip_block_time + 1); // Set node time to tip time
+    BOOST_CHECK(peerman->GetDesirableServiceFlags(peer_flags) == ServiceFlags(NODE_NETWORK_LIMITED | NODE_WITNESS));
+
+    // Check we don't disallow limited peers connections when we are behind but still recoverable (below the connection safety window)
+    SetMockTime(GetTime<std::chrono::seconds>() + std::chrono::seconds{consensus.nPowTargetSpacing * (NODE_NETWORK_LIMITED_ALLOW_CONN_BLOCKS - 1)});
+    BOOST_CHECK(peerman->GetDesirableServiceFlags(peer_flags) == ServiceFlags(NODE_NETWORK_LIMITED | NODE_WITNESS));
+
+    // Check we disallow limited peers connections when we are further than the limited peers safety window
+    SetMockTime(GetTime<std::chrono::seconds>() + std::chrono::seconds{consensus.nPowTargetSpacing * 2});
+    BOOST_CHECK(peerman->GetDesirableServiceFlags(peer_flags) == ServiceFlags(NODE_NETWORK | NODE_WITNESS));
+
+    // By now, we tested that the connections desirable services flags change based on the node's time proximity to the tip.
+    // Now, perform the same tests for when the node receives a block.
+    RegisterValidationInterface(peerman.get());
+
+    // First, verify a block in the past doesn't enable limited peers connections
+    // At this point, our time is (NODE_NETWORK_LIMITED_ALLOW_CONN_BLOCKS + 1) * 10 minutes ahead the tip's time.
+    mineBlock(m_node, /*block_time=*/std::chrono::seconds{tip_block_time + 1});
+    BOOST_CHECK(peerman->GetDesirableServiceFlags(peer_flags) == ServiceFlags(NODE_NETWORK | NODE_WITNESS));
+
+    // Verify a block close to the tip enables limited peers connections
+    mineBlock(m_node, /*block_time=*/GetTime<std::chrono::seconds>());
+    BOOST_CHECK(peerman->GetDesirableServiceFlags(peer_flags) == ServiceFlags(NODE_NETWORK_LIMITED | NODE_WITNESS));
+
+    // Lastly, verify the stale tip checks can disallow limited peers connections after not receiving blocks for a prolonged period.
+    SetMockTime(GetTime<std::chrono::seconds>() + std::chrono::seconds{consensus.nPowTargetSpacing * NODE_NETWORK_LIMITED_ALLOW_CONN_BLOCKS + 1});
+    BOOST_CHECK(peerman->GetDesirableServiceFlags(peer_flags) == ServiceFlags(NODE_NETWORK | NODE_WITNESS));
+}
+
+BOOST_AUTO_TEST_SUITE_END()