fuzz: Add harness for p2p headers sync

src/test/fuzz/CMakeLists.txt

@@ -72,6 +72,7 @@ add_executable(fuzz
   netbase_dns_lookup.cpp
   node_eviction.cpp
   p2p_handshake.cpp
+  p2p_headers_presync.cpp
   p2p_transport_serialization.cpp
   package_eval.cpp
   parse_hd_keypath.cpp

src/test/fuzz/p2p_headers_presync.cpp

@@ -0,0 +1,200 @@
+#include <blockencodings.h>
+#include <net.h>
+#include <net_processing.h>
+#include <netmessagemaker.h>
+#include <node/peerman_args.h>
+#include <pow.h>
+#include <test/fuzz/FuzzedDataProvider.h>
+#include <test/fuzz/fuzz.h>
+#include <test/fuzz/util.h>
+#include <test/util/net.h>
+#include <test/util/script.h>
+#include <test/util/setup_common.h>
+#include <validation.h>
+
+namespace {
+constexpr uint32_t FUZZ_MAX_HEADERS_RESULTS{16};
+
+class HeadersSyncSetup : public TestingSetup
+{
+    std::vector<CNode*> m_connections;
+
+public:
+    HeadersSyncSetup(const ChainType chain_type = ChainType::MAIN,
+                     TestOpts opts = {})
+        : TestingSetup(chain_type, opts)
+    {
+        PeerManager::Options peerman_opts;
+        node::ApplyArgsManOptions(*m_node.args, peerman_opts);
+        peerman_opts.max_headers_result = FUZZ_MAX_HEADERS_RESULTS;
+        m_node.peerman = PeerManager::make(*m_node.connman, *m_node.addrman,
+                                           m_node.banman.get(), *m_node.chainman,
+                                           *m_node.mempool, *m_node.warnings, peerman_opts);
+
+        CConnman::Options options;
+        options.m_msgproc = m_node.peerman.get();
+        m_node.connman->Init(options);
+    }
+
+    void ResetAndInitialize() EXCLUSIVE_LOCKS_REQUIRED(NetEventsInterface::g_msgproc_mutex);
+    void SendMessage(FuzzedDataProvider& fuzzed_data_provider, CSerializedNetMsg&& msg)
+        EXCLUSIVE_LOCKS_REQUIRED(NetEventsInterface::g_msgproc_mutex);
+};
+
+void HeadersSyncSetup::ResetAndInitialize()
+{
+    m_connections.clear();
+    auto& connman = static_cast<ConnmanTestMsg&>(*m_node.connman);
+    connman.StopNodes();
+
+    NodeId id{0};
+    std::vector<ConnectionType> conn_types = {
+        ConnectionType::OUTBOUND_FULL_RELAY,
+        ConnectionType::BLOCK_RELAY,
+        ConnectionType::INBOUND
+    };
+
+    for (auto conn_type : conn_types) {
+        CAddress addr{};
+        m_connections.push_back(new CNode(id++, nullptr, addr, 0, 0, addr, "", conn_type, false));
+        CNode& p2p_node = *m_connections.back();
+
+        connman.Handshake(
+            /*node=*/p2p_node,
+            /*successfully_connected=*/true,
+            /*remote_services=*/ServiceFlags(NODE_NETWORK | NODE_WITNESS),
+            /*local_services=*/ServiceFlags(NODE_NETWORK | NODE_WITNESS),
+            /*version=*/PROTOCOL_VERSION,
+            /*relay_txs=*/true);
+
+        connman.AddTestNode(p2p_node);
+    }
+}
+
+void HeadersSyncSetup::SendMessage(FuzzedDataProvider& fuzzed_data_provider, CSerializedNetMsg&& msg)
+{
+    auto& connman = static_cast<ConnmanTestMsg&>(*m_node.connman);
+    CNode& connection = *PickValue(fuzzed_data_provider, m_connections);
+
+    connman.FlushSendBuffer(connection);
+    (void)connman.ReceiveMsgFrom(connection, std::move(msg));
+    connection.fPauseSend = false;
+    try {
+        connman.ProcessMessagesOnce(connection);
+    } catch (const std::ios_base::failure&) {
+    }
+    m_node.peerman->SendMessages(&connection);
+}
+
+CBlockHeader ConsumeHeader(FuzzedDataProvider& fuzzed_data_provider, const uint256& prev_hash, uint32_t prev_nbits)
+{
+    CBlockHeader header;
+    header.nNonce = 0;
+    // Either use the previous difficulty or let the fuzzer choose
+    header.nBits = fuzzed_data_provider.ConsumeBool() ?
+                       prev_nbits :
+                       fuzzed_data_provider.ConsumeIntegralInRange<uint32_t>(0x17058EBE, 0x1D00FFFF);
+    header.nTime = ConsumeTime(fuzzed_data_provider);
+    header.hashPrevBlock = prev_hash;
+    header.nVersion = fuzzed_data_provider.ConsumeIntegral<int32_t>();
+    return header;
+}
+
+CBlock ConsumeBlock(FuzzedDataProvider& fuzzed_data_provider, const uint256& prev_hash, uint32_t prev_nbits)
+{
+    auto header = ConsumeHeader(fuzzed_data_provider, prev_hash, prev_nbits);
+    // In order to reach the headers acceptance logic, the block is
+    // constructed in a way that will pass the mutation checks.
+    CBlock block{header};
+    CMutableTransaction tx;
+    tx.vin.resize(1);
+    tx.vout.resize(1);
+    tx.vout[0].nValue = 0;
+    tx.vin[0].scriptSig.resize(2);
+    block.vtx.push_back(MakeTransactionRef(tx));
+    block.hashMerkleRoot = block.vtx[0]->GetHash();
+    return block;
+}
+
+void FinalizeHeader(CBlockHeader& header)
+{
+    while (!CheckProofOfWork(header.GetHash(), header.nBits, Params().GetConsensus())) {
+        ++(header.nNonce);
+    }
+}
+
+// Global setup works for this test as state modification (specifically in the
+// block index) would indicate a bug.
+HeadersSyncSetup* g_testing_setup;
+
+void initialize()
+{
+    static auto setup = MakeNoLogFileContext<HeadersSyncSetup>(ChainType::MAIN, {.extra_args = {"-checkpoints=0"}});
+    g_testing_setup = setup.get();
+}
+} // namespace
+
+FUZZ_TARGET(p2p_headers_presync, .init = initialize)
+{
+    ChainstateManager& chainman = *g_testing_setup->m_node.chainman;
+
+    LOCK(NetEventsInterface::g_msgproc_mutex);
+
+    g_testing_setup->ResetAndInitialize();
+
+    FuzzedDataProvider fuzzed_data_provider{buffer.data(), buffer.size()};
+
+    CBlockHeader base{Params().GenesisBlock()};
+    SetMockTime(base.nTime);
+
+    // The chain is just a single block, so this is equal to 1
+    size_t original_index_size{WITH_LOCK(cs_main, return chainman.m_blockman.m_block_index.size())};
+
+    LIMITED_WHILE(fuzzed_data_provider.ConsumeBool(), 100)
+    {
+        auto finalized_block = [&]() {
+            CBlock block = ConsumeBlock(fuzzed_data_provider, base.GetHash(), base.nBits);
+            FinalizeHeader(block);
+            return block;
+        };
+
+        // Send low-work headers, compact blocks, and blocks
+        CallOneOf(
+            fuzzed_data_provider,
+            [&]() NO_THREAD_SAFETY_ANALYSIS {
+                // Send FUZZ_MAX_HEADERS_RESULTS headers
+                std::vector<CBlock> headers;
+                headers.resize(FUZZ_MAX_HEADERS_RESULTS);
+                for (CBlock& header : headers) {
+                    header = ConsumeHeader(fuzzed_data_provider, base.GetHash(), base.nBits);
+                    FinalizeHeader(header);
+                    base = header;
+                }
+
+                auto headers_msg = NetMsg::Make(NetMsgType::HEADERS, TX_WITH_WITNESS(headers));
+                g_testing_setup->SendMessage(fuzzed_data_provider, std::move(headers_msg));
+            },
+            [&]() NO_THREAD_SAFETY_ANALYSIS {
+                // Send a compact block
+                auto block = finalized_block();
+                CBlockHeaderAndShortTxIDs cmpct_block{block, fuzzed_data_provider.ConsumeIntegral<uint64_t>()};
+
+                auto headers_msg = NetMsg::Make(NetMsgType::CMPCTBLOCK, TX_WITH_WITNESS(cmpct_block));
+                g_testing_setup->SendMessage(fuzzed_data_provider, std::move(headers_msg));
+            },
+            [&]() NO_THREAD_SAFETY_ANALYSIS {
+                // Send a block
+                auto block = finalized_block();
+
+                auto headers_msg = NetMsg::Make(NetMsgType::BLOCK, TX_WITH_WITNESS(block));
+                g_testing_setup->SendMessage(fuzzed_data_provider, std::move(headers_msg));
+            });
+    }
+
+    // The headers/blocks sent in this test should never be stored, as the chains don't have the work required
+    // to meet the anti-DoS work threshold. So, if at any point the block index grew in size, then there's a bug
+    // in the headers pre-sync logic.
+    assert(WITH_LOCK(cs_main, return chainman.m_blockman.m_block_index.size()) == original_index_size);
+
+    g_testing_setup->m_node.validation_signals->SyncWithValidationInterfaceQueue();
+}