coinjoin_inouts_tests.cpp

// Copyright (c) 2025 The Dash Core developers
// Distributed under the MIT/X11 software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#include <active/masternode.h>
#include <bls/bls.h>
#include <chain.h>
#include <coinjoin/coinjoin.h>
#include <coinjoin/common.h>
#include <coinjoin/server.h>
#include <evo/chainhelper.h>
#include <llmq/context.h>
#include <masternode/sync.h>
#include <net.h>
#include <node/connection_types.h>
#include <protocol.h>
#include <script/script.h>
#include <streams.h>
#include <test/util/setup_common.h>
#include <uint256.h>
#include <util/check.h>
#include <util/time.h>

#include <boost/test/unit_test.hpp>

#include <algorithm>
#include <array>
#include <cstdint>
#include <memory>
#include <vector>

BOOST_FIXTURE_TEST_SUITE(coinjoin_inouts_tests, TestingSetup)

static CBLSSecretKey MakeSecretKey()
{
    CBLSSecretKey sk;
    sk.MakeNewKey();
    return sk;
}

static CScript P2PKHScript(uint8_t tag = 0x01)
{
    // OP_DUP OP_HASH160 <20-byte-tag> OP_EQUALVERIFY OP_CHECKSIG
    std::vector<unsigned char> hash(20, tag);
    return CScript{} << OP_DUP << OP_HASH160 << hash << OP_EQUALVERIFY << OP_CHECKSIG;
}

BOOST_AUTO_TEST_CASE(broadcasttx_isvalidstructure_good_and_bad)
{
    // Good: equal vin/vout sizes, vin count >= min participants, <= max*entry_size, P2PKH outputs with standard denominations
    CCoinJoinBroadcastTx good;
    {
        CMutableTransaction mtx;
        // Use min pool participants (e.g. 3). Build 3 inputs and 3 denominated outputs
        const int participants = std::max(3, CoinJoin::GetMinPoolParticipants());
        for (int i = 0; i < participants; ++i) {
            CTxIn in;
            in.prevout = COutPoint(uint256::ONE, static_cast<uint32_t>(i));
            mtx.vin.push_back(in);
            // Pick the smallest denomination
            CTxOut out{CoinJoin::GetSmallestDenomination(), P2PKHScript(static_cast<uint8_t>(i))};
            mtx.vout.push_back(out);
        }
        good.tx = MakeTransactionRef(mtx);
        good.m_protxHash = uint256::ONE; // at least one of (outpoint, protxhash) must be set
    }
    BOOST_CHECK(good.IsValidStructure());

    // Bad: both identifiers null
    CCoinJoinBroadcastTx bad_ids = good;
    bad_ids.m_protxHash = uint256{};
    bad_ids.masternodeOutpoint.SetNull();
    BOOST_CHECK(!bad_ids.IsValidStructure());

    // Bad: vin/vout size mismatch
    CCoinJoinBroadcastTx bad_sizes = good;
    {
        CMutableTransaction mtx(*good.tx);
        mtx.vout.pop_back();
        bad_sizes.tx = MakeTransactionRef(mtx);
    }
    BOOST_CHECK(!bad_sizes.IsValidStructure());

    // Bad: non-P2PKH output
    CCoinJoinBroadcastTx bad_script = good;
    {
        CMutableTransaction mtx(*good.tx);
        mtx.vout[0].scriptPubKey = CScript() << OP_RETURN << std::vector<unsigned char>{'x'};
        bad_script.tx = MakeTransactionRef(mtx);
    }
    BOOST_CHECK(!bad_script.IsValidStructure());

    // Bad: non-denominated amount
    CCoinJoinBroadcastTx bad_amount = good;
    {
        CMutableTransaction mtx(*good.tx);
        mtx.vout[0].nValue = 42; // not a valid denom
        bad_amount.tx = MakeTransactionRef(mtx);
    }
    BOOST_CHECK(!bad_amount.IsValidStructure());
}

// Test-only subclass exposing the minimal seams needed to observe how
// ProcessDSSIGNFINALTX treats messages from participants vs. non-participants
// without standing up a full DKG-backed signing session.
class TestableCoinJoinServer : public CCoinJoinServer
{
public:
    using CCoinJoinServer::CCoinJoinServer;

    void EnterSigningState() { nState = POOL_STATE_SIGNING; }

    void SeedParticipant(const CService& addr) EXCLUSIVE_LOCKS_REQUIRED(!cs_coinjoin)
    {
        CCoinJoinEntry entry;
        entry.addr = addr;
        LOCK(cs_coinjoin);
        vecEntries.push_back(std::move(entry));
    }
};

static std::unique_ptr<CNode> MakePeer(NodeId id, uint32_t ipv4)
{
    in_addr peer_in_addr{};
    peer_in_addr.s_addr = htonl(ipv4);
    auto peer = std::make_unique<CNode>(id,
                                        /*sock=*/nullptr,
                                        /*addrIn=*/CAddress{CService{peer_in_addr, 8333}, NODE_NETWORK},
                                        /*nKeyedNetGroupIn=*/0,
                                        /*nLocalHostNonceIn=*/0,
                                        /*addrBindIn=*/CAddress{},
                                        /*addrNameIn=*/std::string{},
                                        /*conn_type_in=*/ConnectionType::INBOUND,
                                        /*inbound_onion=*/false);
    peer->nVersion = PROTOCOL_VERSION;
    peer->SetCommonVersion(PROTOCOL_VERSION);
    return peer;
}

BOOST_AUTO_TEST_CASE(server_signfinaltx_nonparticipant_cannot_abort_session)
{
    BOOST_REQUIRE(m_node.mn_sync);
    m_node.mn_sync->SwitchToNextAsset();
    BOOST_REQUIRE(m_node.mn_sync->IsBlockchainSynced());

    CActiveMasternodeManager mn_activeman(*Assert(m_node.connman), *Assert(m_node.dmnman), MakeSecretKey());
    TestableCoinJoinServer server(m_node.peerman.get(), *Assert(m_node.chainman), *Assert(m_node.connman),
                                  *Assert(m_node.dmnman), *Assert(m_node.dstxman), *Assert(m_node.mn_metaman),
                                  *Assert(m_node.mempool), mn_activeman, *Assert(m_node.mn_sync),
                                  *Assert(m_node.llmq_ctx->isman));

    // Seed an active signing session with one participant. That participant's
    // addr is deliberately not registered with connman -- a session-wide
    // RelayStatus(REJECTED) would therefore see nDisconnected == vecEntries.size()
    // and reset the pool state to POOL_STATE_IDLE via SetNull().
    auto participant = MakePeer(/*id=*/7, /*ipv4=*/0x0a000001);
    server.SeedParticipant(participant->addr);
    server.EnterSigningState();
    BOOST_REQUIRE_EQUAL(server.GetState(), int{POOL_STATE_SIGNING});

    auto nonparticipant = MakePeer(/*id=*/42, /*ipv4=*/0x01020304);
    BOOST_REQUIRE(!(nonparticipant->addr == participant->addr));

    const size_t max_txins{CoinJoin::GetMaxPoolInputOutputCount()};
    CDataStream stream{SER_NETWORK, PROTOCOL_VERSION};
    WriteCompactSize(stream, max_txins + 1);

    BOOST_CHECK_NO_THROW(server.ProcessMessage(*nonparticipant, NetMsgType::DSSIGNFINALTX, stream));

    // The non-participant must be rejected without touching session-wide state:
    // the stream body must not have been read past the compact-size prefix, and
    // the pool must still be in POOL_STATE_SIGNING with its entry intact.
    BOOST_CHECK_EQUAL(stream.size(), GetSizeOfCompactSize(max_txins + 1));
    BOOST_CHECK_EQUAL(server.GetState(), int{POOL_STATE_SIGNING});
    BOOST_CHECK_EQUAL(server.GetEntriesCount(), 1);
}

BOOST_AUTO_TEST_CASE(server_signfinaltx_participant_oversized_count_is_rejected_locally)
{
    BOOST_REQUIRE(m_node.mn_sync);
    m_node.mn_sync->SwitchToNextAsset();
    BOOST_REQUIRE(m_node.mn_sync->IsBlockchainSynced());

    CActiveMasternodeManager mn_activeman(*Assert(m_node.connman), *Assert(m_node.dmnman), MakeSecretKey());
    TestableCoinJoinServer server(m_node.peerman.get(), *Assert(m_node.chainman), *Assert(m_node.connman),
                                  *Assert(m_node.dmnman), *Assert(m_node.dstxman), *Assert(m_node.mn_metaman),
                                  *Assert(m_node.mempool), mn_activeman, *Assert(m_node.mn_sync),
                                  *Assert(m_node.llmq_ctx->isman));

    // Same setup, but this time the oversized DSSIGNFINALTX comes from the
    // session participant itself. It must still be rejected without materializing
    // the txin vector and without collapsing the session for everyone else.
    auto participant = MakePeer(/*id=*/7, /*ipv4=*/0x0a000001);
    server.SeedParticipant(participant->addr);
    server.EnterSigningState();

    const size_t max_txins{CoinJoin::GetMaxPoolInputOutputCount()};
    CDataStream stream{SER_NETWORK, PROTOCOL_VERSION};
    WriteCompactSize(stream, max_txins + 1);

    BOOST_CHECK_NO_THROW(server.ProcessMessage(*participant, NetMsgType::DSSIGNFINALTX, stream));
    BOOST_CHECK_EQUAL(stream.size(), 0U);
    BOOST_CHECK_EQUAL(server.GetState(), int{POOL_STATE_SIGNING});
    BOOST_CHECK_EQUAL(server.GetEntriesCount(), 1);

    // A count beyond the generic CompactSize cap is a malformed message, not a
    // CoinJoin-level violation: it throws the standard deserialization error out
    // to net processing. No txin is materialized and the session is left intact,
    // so honest participants are unaffected.
    CDataStream huge_stream{SER_NETWORK, PROTOCOL_VERSION};
    WriteCompactSize(huge_stream, uint64_t{MAX_SIZE} + 1);

    BOOST_CHECK_THROW(server.ProcessMessage(*participant, NetMsgType::DSSIGNFINALTX, huge_stream),
                      std::ios_base::failure);
    BOOST_CHECK_EQUAL(server.GetState(), int{POOL_STATE_SIGNING});
    BOOST_CHECK_EQUAL(server.GetEntriesCount(), 1);
}

BOOST_AUTO_TEST_CASE(entry_deserializes_vectors_through_wire_cap)
{
    const size_t wire_cap{CoinJoin::GetMaxPoolInputOutputCount()};
    BOOST_REQUIRE_GT(wire_cap, COINJOIN_ENTRY_MAX_SIZE);

    for (const size_t count : {size_t{0}, COINJOIN_ENTRY_MAX_SIZE, COINJOIN_ENTRY_MAX_SIZE + 1, wire_cap}) {
        BOOST_TEST_CONTEXT("count=" << count)
        {
            CCoinJoinEntry entry;
            entry.vecTxDSIn.resize(count);
            entry.vecTxOut.resize(count);

            CDataStream stream{SER_NETWORK, PROTOCOL_VERSION};
            stream << entry;

            CCoinJoinEntry roundtripped;
            BOOST_CHECK_NO_THROW(stream >> roundtripped);
            BOOST_CHECK_EQUAL(roundtripped.vecTxDSIn.size(), count);
            BOOST_CHECK_EQUAL(roundtripped.vecTxOut.size(), count);
        }
    }
}

BOOST_AUTO_TEST_CASE(entry_rejects_inputs_above_wire_cap_before_materializing)
{
    const size_t wire_cap{CoinJoin::GetMaxPoolInputOutputCount()};
    CDataStream stream{SER_NETWORK, PROTOCOL_VERSION};
    WriteCompactSize(stream, wire_cap + 1);

    CCoinJoinEntry entry;
    BOOST_CHECK_THROW(stream >> entry, std::ios_base::failure);
    BOOST_CHECK(entry.vecTxDSIn.empty());
}

BOOST_AUTO_TEST_CASE(entry_rejects_outputs_above_wire_cap_before_materializing)
{
    const size_t wire_cap{CoinJoin::GetMaxPoolInputOutputCount()};
    CDataStream stream{SER_NETWORK, PROTOCOL_VERSION};
    WriteCompactSize(stream, 0);
    stream << MakeTransactionRef(CMutableTransaction{});
    WriteCompactSize(stream, wire_cap + 1);

    CCoinJoinEntry entry;
    BOOST_CHECK_THROW(stream >> entry, std::ios_base::failure);
    BOOST_CHECK(entry.vecTxOut.empty());
}

BOOST_AUTO_TEST_CASE(queue_timeout_bounds)
{
    CCoinJoinQueue dsq;
    dsq.nDenom = CoinJoin::AmountToDenomination(CoinJoin::GetSmallestDenomination());
    dsq.m_protxHash = uint256::ONE;
    dsq.nTime = GetAdjustedTime();
    // current time -> not out of bounds
    BOOST_CHECK(!dsq.IsTimeOutOfBounds());

    // Too old (beyond COINJOIN_QUEUE_TIMEOUT)
    SetMockTime(GetTime() + (COINJOIN_QUEUE_TIMEOUT + 1));
    BOOST_CHECK(dsq.IsTimeOutOfBounds());

    // Too far in the future
    SetMockTime(GetTime() - 2 * (COINJOIN_QUEUE_TIMEOUT + 1)); // move back to anchor baseline
    dsq.nTime = GetAdjustedTime() + (COINJOIN_QUEUE_TIMEOUT + 1);
    BOOST_CHECK(dsq.IsTimeOutOfBounds());

    // Reset mock time
    SetMockTime(0);
}
BOOST_AUTO_TEST_SUITE_END()