denialofservice_tests.cpp

// Copyright (c) 2011-2021 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

// Unit tests for denial-of-service detection/prevention code

#include <arith_uint256.h>
#include <banman.h>
#include <chainparams.h>
#include <net.h>
#include <net_processing.h>
#include <pubkey.h>
#include <script/sign.h>
#include <script/signingprovider.h>
#include <script/standard.h>
#include <serialize.h>
#include <test/util/net.h>
#include <test/util/setup_common.h>
#include <txorphanage.h>
#include <util/string.h>
#include <util/system.h>
#include <util/time.h>
#include <validation.h>

#include <array>
#include <stdint.h>

#include <boost/test/unit_test.hpp>

static CService ip(uint32_t i)
{
    struct in_addr s;
    s.s_addr = i;
    return CService(CNetAddr(s), Params().GetDefaultPort());
}

static NodeId id = 0;

void UpdateLastBlockAnnounceTime(NodeId node, int64_t time_in_seconds);

BOOST_FIXTURE_TEST_SUITE(denialofservice_tests, TestingSetup)

// Test eviction of an outbound peer whose chain never advances
// Mock a node connection, and use mocktime to simulate a peer
// which never sends any headers messages.  PeerLogic should
// decide to evict that outbound peer, after the appropriate timeouts.
// Note that we protect 4 outbound nodes from being subject to
// this logic; this test takes advantage of that protection only
// being applied to nodes which send headers with sufficient
// work.
BOOST_AUTO_TEST_CASE(outbound_slow_chain_eviction)
{
    const CChainParams& chainparams = Params();
    auto connman = std::make_unique<CConnman>(0x1337, 0x1337, *m_node.addrman);
    // Disable inactivity checks for this test to avoid interference
    static_cast<ConnmanTestMsg*>(connman.get())->SetPeerConnectTimeout(99999s);
    auto peerLogic = PeerManager::make(chainparams, *connman, *m_node.addrman, nullptr,
                                       *m_node.chainman, *m_node.mempool, false);

    // Mock an outbound peer
    CAddress addr1(ip(0xa0b0c001), NODE_NONE);
    CNode dummyNode1(id++, ServiceFlags(NODE_NETWORK | NODE_WITNESS), INVALID_SOCKET, addr1, /*nKeyedNetGroupIn=*/0, /*nLocalHostNonceIn=*/0, CAddress(), /*addrNameIn=*/"", ConnectionType::OUTBOUND_FULL_RELAY, /*inbound_onion=*/false);
    dummyNode1.SetCommonVersion(PROTOCOL_VERSION);

    peerLogic->InitializeNode(&dummyNode1);
    dummyNode1.fSuccessfullyConnected = true;

    // This test requires that we have a chain with non-zero work.
    {
        LOCK(cs_main);
        BOOST_CHECK(m_node.chainman->ActiveChain().Tip() != nullptr);
        BOOST_CHECK(m_node.chainman->ActiveChain().Tip()->nChainWork > 0);
    }

    // Test starts here
    {
        LOCK(dummyNode1.cs_sendProcessing);
        BOOST_CHECK(peerLogic->SendMessages(&dummyNode1)); // should result in getheaders
    }
    {
        LOCK(dummyNode1.cs_vSend);
        BOOST_CHECK(dummyNode1.vSendMsg.size() > 0);
        dummyNode1.vSendMsg.clear();
    }

    int64_t nStartTime = GetTime();
    // Wait 21 minutes
    SetMockTime(nStartTime+21*60);
    {
        LOCK(dummyNode1.cs_sendProcessing);
        BOOST_CHECK(peerLogic->SendMessages(&dummyNode1)); // should result in getheaders
    }
    {
        LOCK(dummyNode1.cs_vSend);
        BOOST_CHECK(dummyNode1.vSendMsg.size() > 0);
    }
    // Wait 3 more minutes
    SetMockTime(nStartTime+24*60);
    {
        LOCK(dummyNode1.cs_sendProcessing);
        BOOST_CHECK(peerLogic->SendMessages(&dummyNode1)); // should result in disconnect
    }
    BOOST_CHECK(dummyNode1.fDisconnect == true);

    peerLogic->FinalizeNode(dummyNode1);
}

static void AddRandomOutboundPeer(std::vector<CNode*>& vNodes, PeerManager& peerLogic, ConnmanTestMsg& connman, ConnectionType connType)
{
    CAddress addr(ip(g_insecure_rand_ctx.randbits(32)), NODE_NONE);
    vNodes.emplace_back(new CNode(id++, ServiceFlags(NODE_NETWORK | NODE_WITNESS), INVALID_SOCKET, addr, /*nKeyedNetGroupIn=*/0, /*nLocalHostNonceIn=*/0, CAddress(), /*addrNameIn=*/"", connType, /*inbound_onion=*/false));
    CNode &node = *vNodes.back();
    node.SetCommonVersion(PROTOCOL_VERSION);

    peerLogic.InitializeNode(&node);
    node.fSuccessfullyConnected = true;

    connman.AddTestNode(node);
}

BOOST_AUTO_TEST_CASE(stale_tip_peer_management)
{
    const CChainParams& chainparams = Params();
    auto connman = std::make_unique<ConnmanTestMsg>(0x1337, 0x1337, *m_node.addrman);
    auto peerLogic = PeerManager::make(chainparams, *connman, *m_node.addrman, nullptr,
                                       *m_node.chainman, *m_node.mempool, false);

    constexpr int max_outbound_full_relay = MAX_OUTBOUND_FULL_RELAY_CONNECTIONS;
    CConnman::Options options;
    options.nMaxConnections = DEFAULT_MAX_PEER_CONNECTIONS;
    options.m_max_outbound_full_relay = max_outbound_full_relay;
    options.nMaxFeeler = MAX_FEELER_CONNECTIONS;

    const auto time_init{GetTime<std::chrono::seconds>()};
    SetMockTime(time_init);
    const auto time_later{time_init + 3 * std::chrono::seconds{chainparams.GetConsensus().nPowTargetSpacing} + 1s};
    connman->Init(options);
    std::vector<CNode *> vNodes;

    // Mock some outbound peers
    for (int i = 0; i < max_outbound_full_relay; ++i) {
        AddRandomOutboundPeer(vNodes, *peerLogic, *connman, ConnectionType::OUTBOUND_FULL_RELAY);
    }

    peerLogic->CheckForStaleTipAndEvictPeers();

    // No nodes should be marked for disconnection while we have no extra peers
    for (const CNode *node : vNodes) {
        BOOST_CHECK(node->fDisconnect == false);
    }

    SetMockTime(time_later);

    // Now tip should definitely be stale, and we should look for an extra
    // outbound peer
    peerLogic->CheckForStaleTipAndEvictPeers();
    BOOST_CHECK(connman->GetTryNewOutboundPeer());

    // Still no peers should be marked for disconnection
    for (const CNode *node : vNodes) {
        BOOST_CHECK(node->fDisconnect == false);
    }

    // If we add one more peer, something should get marked for eviction
    // on the next check (since we're mocking the time to be in the future, the
    // required time connected check should be satisfied).
    SetMockTime(time_init);
    AddRandomOutboundPeer(vNodes, *peerLogic, *connman, ConnectionType::OUTBOUND_FULL_RELAY);
    SetMockTime(time_later);

    peerLogic->CheckForStaleTipAndEvictPeers();
    for (int i = 0; i < max_outbound_full_relay; ++i) {
        BOOST_CHECK(vNodes[i]->fDisconnect == false);
    }
    // Last added node should get marked for eviction
    BOOST_CHECK(vNodes.back()->fDisconnect == true);

    vNodes.back()->fDisconnect = false;

    // Update the last announced block time for the last
    // peer, and check that the next newest node gets evicted.
    UpdateLastBlockAnnounceTime(vNodes.back()->GetId(), GetTime());

    peerLogic->CheckForStaleTipAndEvictPeers();
    for (int i = 0; i < max_outbound_full_relay - 1; ++i) {
        BOOST_CHECK(vNodes[i]->fDisconnect == false);
    }
    BOOST_CHECK(vNodes[max_outbound_full_relay-1]->fDisconnect == true);
    BOOST_CHECK(vNodes.back()->fDisconnect == false);

    for (const CNode *node : vNodes) {
        peerLogic->FinalizeNode(*node);
    }

    connman->ClearTestNodes();
}

BOOST_AUTO_TEST_CASE(block_relay_only_eviction)
{
    const CChainParams& chainparams = Params();
    auto connman = std::make_unique<ConnmanTestMsg>(0x1337, 0x1337, *m_node.addrman);
    auto peerLogic = PeerManager::make(chainparams, *connman, *m_node.addrman, nullptr,
                                       *m_node.chainman, *m_node.mempool, false);

    constexpr int max_outbound_block_relay{MAX_BLOCK_RELAY_ONLY_CONNECTIONS};
    constexpr int64_t MINIMUM_CONNECT_TIME{30};
    CConnman::Options options;
    options.nMaxConnections = DEFAULT_MAX_PEER_CONNECTIONS;
    options.m_max_outbound_full_relay = MAX_OUTBOUND_FULL_RELAY_CONNECTIONS;
    options.m_max_outbound_block_relay = max_outbound_block_relay;

    connman->Init(options);
    std::vector<CNode*> vNodes;

    // Add block-relay-only peers up to the limit
    for (int i = 0; i < max_outbound_block_relay; ++i) {
        AddRandomOutboundPeer(vNodes, *peerLogic, *connman, ConnectionType::BLOCK_RELAY);
    }
    peerLogic->CheckForStaleTipAndEvictPeers();

    for (int i = 0; i < max_outbound_block_relay; ++i) {
        BOOST_CHECK(vNodes[i]->fDisconnect == false);
    }

    // Add an extra block-relay-only peer breaking the limit (mocks logic in ThreadOpenConnections)
    AddRandomOutboundPeer(vNodes, *peerLogic, *connman, ConnectionType::BLOCK_RELAY);
    peerLogic->CheckForStaleTipAndEvictPeers();

    // The extra peer should only get marked for eviction after MINIMUM_CONNECT_TIME
    for (int i = 0; i < max_outbound_block_relay; ++i) {
        BOOST_CHECK(vNodes[i]->fDisconnect == false);
    }
    BOOST_CHECK(vNodes.back()->fDisconnect == false);

    SetMockTime(GetTime() + MINIMUM_CONNECT_TIME + 1);
    peerLogic->CheckForStaleTipAndEvictPeers();
    for (int i = 0; i < max_outbound_block_relay; ++i) {
        BOOST_CHECK(vNodes[i]->fDisconnect == false);
    }
    BOOST_CHECK(vNodes.back()->fDisconnect == true);

    // Update the last block time for the extra peer,
    // and check that the next youngest peer gets evicted.
    vNodes.back()->fDisconnect = false;
    vNodes.back()->m_last_block_time = GetTime<std::chrono::seconds>();

    peerLogic->CheckForStaleTipAndEvictPeers();
    for (int i = 0; i < max_outbound_block_relay - 1; ++i) {
        BOOST_CHECK(vNodes[i]->fDisconnect == false);
    }
    BOOST_CHECK(vNodes[max_outbound_block_relay - 1]->fDisconnect == true);
    BOOST_CHECK(vNodes.back()->fDisconnect == false);

    for (const CNode* node : vNodes) {
        peerLogic->FinalizeNode(*node);
    }
    connman->ClearTestNodes();
}

BOOST_AUTO_TEST_CASE(peer_discouragement)
{
    const CChainParams& chainparams = Params();
    auto banman = std::make_unique<BanMan>(m_args.GetDataDirBase() / "banlist", nullptr, DEFAULT_MISBEHAVING_BANTIME);
    auto connman = std::make_unique<ConnmanTestMsg>(0x1337, 0x1337, *m_node.addrman);
    auto peerLogic = PeerManager::make(chainparams, *connman, *m_node.addrman, banman.get(),
                                       *m_node.chainman, *m_node.mempool, false);

    CNetAddr tor_netaddr;
    BOOST_REQUIRE(
        tor_netaddr.SetSpecial("pg6mmjiyjmcrsslvykfwnntlaru7p5svn6y2ymmju6nubxndf4pscryd.onion"));
    const CService tor_service{tor_netaddr, Params().GetDefaultPort()};

    const std::array<CAddress, 3> addr{CAddress{ip(0xa0b0c001), NODE_NONE},
                                       CAddress{ip(0xa0b0c002), NODE_NONE},
                                       CAddress{tor_service, NODE_NONE}};

    const CNetAddr other_addr{ip(0xa0b0ff01)}; // Not any of addr[].

    std::array<CNode*, 3> nodes;

    banman->ClearBanned();
    nodes[0] = new CNode{id++, NODE_NETWORK, INVALID_SOCKET, addr[0], /*nKeyedNetGroupIn=*/0,
                         /*nLocalHostNonceIn=*/0, CAddress(), /*addrNameIn=*/"",
                         ConnectionType::INBOUND, /*inbound_onion=*/false};
    nodes[0]->SetCommonVersion(PROTOCOL_VERSION);
    peerLogic->InitializeNode(nodes[0]);
    nodes[0]->fSuccessfullyConnected = true;
    connman->AddTestNode(*nodes[0]);
    peerLogic->Misbehaving(nodes[0]->GetId(), DISCOURAGEMENT_THRESHOLD, /*message=*/""); // Should be discouraged
    {
        LOCK(nodes[0]->cs_sendProcessing);
        BOOST_CHECK(peerLogic->SendMessages(nodes[0]));
    }
    BOOST_CHECK(banman->IsDiscouraged(addr[0]));
    BOOST_CHECK(nodes[0]->fDisconnect);
    BOOST_CHECK(!banman->IsDiscouraged(other_addr)); // Different address, not discouraged

    nodes[1] = new CNode{id++, NODE_NETWORK, INVALID_SOCKET, addr[1], /*nKeyedNetGroupIn=*/1,
                         /*nLocalHostNonceIn=*/1, CAddress(), /*addrNameIn=*/"",
                         ConnectionType::INBOUND, /*inbound_onion=*/false};
    nodes[1]->SetCommonVersion(PROTOCOL_VERSION);
    peerLogic->InitializeNode(nodes[1]);
    nodes[1]->fSuccessfullyConnected = true;
    connman->AddTestNode(*nodes[1]);
    peerLogic->Misbehaving(nodes[1]->GetId(), DISCOURAGEMENT_THRESHOLD - 1, /*message=*/"");
    {
        LOCK(nodes[1]->cs_sendProcessing);
        BOOST_CHECK(peerLogic->SendMessages(nodes[1]));
    }
    // [0] is still discouraged/disconnected.
    BOOST_CHECK(banman->IsDiscouraged(addr[0]));
    BOOST_CHECK(nodes[0]->fDisconnect);
    // [1] is not discouraged/disconnected yet.
    BOOST_CHECK(!banman->IsDiscouraged(addr[1]));
    BOOST_CHECK(!nodes[1]->fDisconnect);
    peerLogic->Misbehaving(nodes[1]->GetId(), 1, /*message=*/""); // [1] reaches discouragement threshold
    {
        LOCK(nodes[1]->cs_sendProcessing);
        BOOST_CHECK(peerLogic->SendMessages(nodes[1]));
    }
    // Expect both [0] and [1] to be discouraged/disconnected now.
    BOOST_CHECK(banman->IsDiscouraged(addr[0]));
    BOOST_CHECK(nodes[0]->fDisconnect);
    BOOST_CHECK(banman->IsDiscouraged(addr[1]));
    BOOST_CHECK(nodes[1]->fDisconnect);

    // Make sure non-IP peers are discouraged and disconnected properly.

    nodes[2] = new CNode{id++, NODE_NETWORK, INVALID_SOCKET, addr[2], /*nKeyedNetGroupIn=*/1,
                         /*nLocalHostNonceIn=*/1, CAddress(), /*addrNameIn=*/"",
                         ConnectionType::OUTBOUND_FULL_RELAY, /*inbound_onion=*/false};
    nodes[2]->SetCommonVersion(PROTOCOL_VERSION);
    peerLogic->InitializeNode(nodes[2]);
    nodes[2]->fSuccessfullyConnected = true;
    connman->AddTestNode(*nodes[2]);
    peerLogic->Misbehaving(nodes[2]->GetId(), DISCOURAGEMENT_THRESHOLD, /*message=*/"");
    {
        LOCK(nodes[2]->cs_sendProcessing);
        BOOST_CHECK(peerLogic->SendMessages(nodes[2]));
    }
    BOOST_CHECK(banman->IsDiscouraged(addr[0]));
    BOOST_CHECK(banman->IsDiscouraged(addr[1]));
    BOOST_CHECK(banman->IsDiscouraged(addr[2]));
    BOOST_CHECK(nodes[0]->fDisconnect);
    BOOST_CHECK(nodes[1]->fDisconnect);
    BOOST_CHECK(nodes[2]->fDisconnect);

    for (CNode* node : nodes) {
        peerLogic->FinalizeNode(*node);
    }
    connman->ClearTestNodes();
}

BOOST_AUTO_TEST_CASE(DoS_bantime)
{
    const CChainParams& chainparams = Params();
    auto banman = std::make_unique<BanMan>(m_args.GetDataDirBase() / "banlist", nullptr, DEFAULT_MISBEHAVING_BANTIME);
    auto connman = std::make_unique<CConnman>(0x1337, 0x1337, *m_node.addrman);
    auto peerLogic = PeerManager::make(chainparams, *connman, *m_node.addrman, banman.get(),
                                       *m_node.chainman, *m_node.mempool, false);

    banman->ClearBanned();
    int64_t nStartTime = GetTime();
    SetMockTime(nStartTime); // Overrides future calls to GetTime()

    CAddress addr(ip(0xa0b0c001), NODE_NONE);
    CNode dummyNode(id++, NODE_NETWORK, INVALID_SOCKET, addr, /*nKeyedNetGroupIn=*/4, /*nLocalHostNonceIn=*/4, CAddress(), /*addrNameIn=*/"", ConnectionType::INBOUND, /*inbound_onion=*/false);
    dummyNode.SetCommonVersion(PROTOCOL_VERSION);
    peerLogic->InitializeNode(&dummyNode);
    dummyNode.fSuccessfullyConnected = true;

    peerLogic->Misbehaving(dummyNode.GetId(), DISCOURAGEMENT_THRESHOLD, /*message=*/"");
    {
        LOCK(dummyNode.cs_sendProcessing);
        BOOST_CHECK(peerLogic->SendMessages(&dummyNode));
    }
    BOOST_CHECK(banman->IsDiscouraged(addr));

    peerLogic->FinalizeNode(dummyNode);
}

class TxOrphanageTest : public TxOrphanage
{
public:
    inline size_t CountOrphans() const EXCLUSIVE_LOCKS_REQUIRED(g_cs_orphans)
    {
        return m_orphans.size();
    }

    CTransactionRef RandomOrphan() EXCLUSIVE_LOCKS_REQUIRED(g_cs_orphans)
    {
        std::map<uint256, OrphanTx>::iterator it;
        it = m_orphans.lower_bound(InsecureRand256());
        if (it == m_orphans.end())
            it = m_orphans.begin();
        return it->second.tx;
    }
};

static void MakeNewKeyWithFastRandomContext(CKey& key)
{
    std::vector<unsigned char> keydata;
    keydata = g_insecure_rand_ctx.randbytes(32);
    key.Set(keydata.data(), keydata.data() + keydata.size(), /*fCompressedIn=*/true);
    assert(key.IsValid());
}

BOOST_AUTO_TEST_CASE(DoS_mapOrphans)
{
    // This test had non-deterministic coverage due to
    // randomly selected seeds.
    // This seed is chosen so that all branches of the function
    // ecdsa_signature_parse_der_lax are executed during this test.
    // Specifically branches that run only when an ECDSA
    // signature's R and S values have leading zeros.
    g_insecure_rand_ctx = FastRandomContext(ArithToUint256(arith_uint256(33)));

    TxOrphanageTest orphanage;
    CKey key;
    MakeNewKeyWithFastRandomContext(key);
    FillableSigningProvider keystore;
    BOOST_CHECK(keystore.AddKey(key));

    LOCK(g_cs_orphans);

    // 50 orphan transactions:
    for (int i = 0; i < 50; i++)
    {
        CMutableTransaction tx;
        tx.vin.resize(1);
        tx.vin[0].prevout.n = 0;
        tx.vin[0].prevout.hash = InsecureRand256();
        tx.vin[0].scriptSig << OP_1;
        tx.vout.resize(1);
        tx.vout[0].nValue = 1*CENT;
        tx.vout[0].scriptPubKey = GetScriptForDestination(PKHash(key.GetPubKey()));

        orphanage.AddTx(MakeTransactionRef(tx), i);
    }

    // ... and 50 that depend on other orphans:
    for (int i = 0; i < 50; i++)
    {
        CTransactionRef txPrev = orphanage.RandomOrphan();

        CMutableTransaction tx;
        tx.vin.resize(1);
        tx.vin[0].prevout.n = 0;
        tx.vin[0].prevout.hash = txPrev->GetHash();
        tx.vout.resize(1);
        tx.vout[0].nValue = 1*CENT;
        tx.vout[0].scriptPubKey = GetScriptForDestination(PKHash(key.GetPubKey()));
        BOOST_CHECK(SignSignature(keystore, *txPrev, tx, 0, SIGHASH_ALL));

        orphanage.AddTx(MakeTransactionRef(tx), i);
    }

    // This really-big orphan should be ignored:
    for (int i = 0; i < 10; i++)
    {
        CTransactionRef txPrev = orphanage.RandomOrphan();

        CMutableTransaction tx;
        tx.vout.resize(1);
        tx.vout[0].nValue = 1*CENT;
        tx.vout[0].scriptPubKey = GetScriptForDestination(PKHash(key.GetPubKey()));
        tx.vin.resize(2777);
        for (unsigned int j = 0; j < tx.vin.size(); j++)
        {
            tx.vin[j].prevout.n = j;
            tx.vin[j].prevout.hash = txPrev->GetHash();
        }
        BOOST_CHECK(SignSignature(keystore, *txPrev, tx, 0, SIGHASH_ALL));
        // Re-use same signature for other inputs
        // (they don't have to be valid for this test)
        for (unsigned int j = 1; j < tx.vin.size(); j++)
            tx.vin[j].scriptSig = tx.vin[0].scriptSig;

        BOOST_CHECK(!orphanage.AddTx(MakeTransactionRef(tx), i));
    }

    // Test EraseOrphansFor:
    for (NodeId i = 0; i < 3; i++)
    {
        size_t sizeBefore = orphanage.CountOrphans();
        orphanage.EraseForPeer(i);
        BOOST_CHECK(orphanage.CountOrphans() < sizeBefore);
    }

    // Test LimitOrphanTxSize() function:
    orphanage.LimitOrphans(40);
    BOOST_CHECK(orphanage.CountOrphans() <= 40);
    orphanage.LimitOrphans(10);
    BOOST_CHECK(orphanage.CountOrphans() <= 10);
    orphanage.LimitOrphans(0);
    BOOST_CHECK(orphanage.CountOrphans() == 0);
}

BOOST_AUTO_TEST_SUITE_END()