1 files changed, 140 insertions, 1 deletions
diff --git a/src/test/fuzz/rbf.cpp b/src/test/fuzz/rbf.cpp
index aa6385d12d..64785948f6 100644
--- a/src/test/fuzz/rbf.cpp
+++ b/src/test/fuzz/rbf.cpp
@@ -23,12 +23,30 @@ namespace {
 const BasicTestingSetup* g_setup;
 } // namespace
 
+const int NUM_ITERS = 10000;
+
+std::vector<COutPoint> g_outpoints;
+
 void initialize_rbf()
 {
     static const auto testing_setup = MakeNoLogFileContext<>();
     g_setup = testing_setup.get();
 }
 
+void initialize_package_rbf()
+{
+    static const auto testing_setup = MakeNoLogFileContext<>();
+    g_setup = testing_setup.get();
+
+    // Create a fixed set of unique "UTXOs" to source parents from
+    // to avoid fuzzer giving circular references
+    for (int i = 0; i < NUM_ITERS; ++i) {
+        g_outpoints.emplace_back();
+        g_outpoints.back().n = i;
+    }
+
+}
+
 FUZZ_TARGET(rbf, .init = initialize_rbf)
 {
     FuzzedDataProvider fuzzed_data_provider(buffer.data(), buffer.size());
@@ -40,7 +58,7 @@ FUZZ_TARGET(rbf, .init = initialize_rbf)
 
     CTxMemPool pool{MemPoolOptionsForTest(g_setup->m_node)};
 
-    LIMITED_WHILE(fuzzed_data_provider.ConsumeBool(), 10000)
+    LIMITED_WHILE(fuzzed_data_provider.ConsumeBool(), NUM_ITERS)
     {
         const std::optional<CMutableTransaction> another_mtx = ConsumeDeserializable<CMutableTransaction>(fuzzed_data_provider, TX_WITH_WITNESS);
         if (!another_mtx) {
@@ -63,3 +81,124 @@ FUZZ_TARGET(rbf, .init = initialize_rbf)
         (void)IsRBFOptIn(tx, pool);
     }
 }
+
+FUZZ_TARGET(package_rbf, .init = initialize_package_rbf)
+{
+    FuzzedDataProvider fuzzed_data_provider(buffer.data(), buffer.size());
+    SetMockTime(ConsumeTime(fuzzed_data_provider));
+
+    std::optional<CMutableTransaction> child = ConsumeDeserializable<CMutableTransaction>(fuzzed_data_provider, TX_WITH_WITNESS);
+    if (!child) return;
+
+    CTxMemPool pool{MemPoolOptionsForTest(g_setup->m_node)};
+
+    // Add a bunch of parent-child pairs to the mempool, and remember them.
+    std::vector<CTransaction> mempool_txs;
+    size_t iter{0};
+
+    int32_t replacement_vsize = fuzzed_data_provider.ConsumeIntegralInRange<int32_t>(1, 1000000);
+
+    // Keep track of the total vsize of CTxMemPoolEntry's being added to the mempool to avoid overflow
+    // Add replacement_vsize since this is added to new diagram during RBF check
+    int64_t running_vsize_total{replacement_vsize};
+
+    LOCK2(cs_main, pool.cs);
+
+    LIMITED_WHILE(fuzzed_data_provider.ConsumeBool(), NUM_ITERS)
+    {
+        // Make sure txns only have one input, and that a unique input is given to avoid circular references
+        std::optional<CMutableTransaction> parent = ConsumeDeserializable<CMutableTransaction>(fuzzed_data_provider, TX_WITH_WITNESS);
+        if (!parent) {
+            return;
+        }
+        assert(iter <= g_outpoints.size());
+        parent->vin.resize(1);
+        parent->vin[0].prevout = g_outpoints[iter++];
+
+        mempool_txs.emplace_back(*parent);
+        const auto parent_entry = ConsumeTxMemPoolEntry(fuzzed_data_provider, mempool_txs.back());
+        running_vsize_total += parent_entry.GetTxSize();
+        if (running_vsize_total > std::numeric_limits<int32_t>::max()) {
+            // We aren't adding this final tx to mempool, so we don't want to conflict with it
+            mempool_txs.pop_back();
+            break;
+        }
+        pool.addUnchecked(parent_entry);
+        if (fuzzed_data_provider.ConsumeBool() && !child->vin.empty()) {
+            child->vin[0].prevout = COutPoint{mempool_txs.back().GetHash(), 0};
+        }
+        mempool_txs.emplace_back(*child);
+        const auto child_entry = ConsumeTxMemPoolEntry(fuzzed_data_provider, mempool_txs.back());
+        running_vsize_total += child_entry.GetTxSize();
+        if (running_vsize_total > std::numeric_limits<int32_t>::max()) {
+            // We aren't adding this final tx to mempool, so we don't want to conflict with it
+            mempool_txs.pop_back();
+            break;
+        }
+        pool.addUnchecked(child_entry);
+
+        if (fuzzed_data_provider.ConsumeBool()) {
+            pool.PrioritiseTransaction(mempool_txs.back().GetHash().ToUint256(), fuzzed_data_provider.ConsumeIntegralInRange<int32_t>(-100000, 100000));
+        }
+    }
+
+    // Pick some transactions at random to be the direct conflicts
+    CTxMemPool::setEntries direct_conflicts;
+    for (auto& tx : mempool_txs) {
+        if (fuzzed_data_provider.ConsumeBool()) {
+            direct_conflicts.insert(*pool.GetIter(tx.GetHash()));
+        }
+    }
+
+    // Calculate all conflicts:
+    CTxMemPool::setEntries all_conflicts;
+    for (auto& txiter : direct_conflicts) {
+        pool.CalculateDescendants(txiter, all_conflicts);
+    }
+
+    // Calculate the chunks for a replacement.
+    CAmount replacement_fees = ConsumeMoney(fuzzed_data_provider);
+    auto calc_results{pool.CalculateChunksForRBF(replacement_fees, replacement_vsize, direct_conflicts, all_conflicts)};
+
+    if (calc_results.has_value()) {
+        // Sanity checks on the chunks.
+
+        // Feerates are monotonically decreasing.
+        FeeFrac first_sum;
+        for (size_t i = 0; i < calc_results->first.size(); ++i) {
+            first_sum += calc_results->first[i];
+            if (i) assert(!(calc_results->first[i - 1] << calc_results->first[i]));
+        }
+        FeeFrac second_sum;
+        for (size_t i = 0; i < calc_results->second.size(); ++i) {
+            second_sum += calc_results->second[i];
+            if (i) assert(!(calc_results->second[i - 1] << calc_results->second[i]));
+        }
+
+        FeeFrac replaced;
+        for (auto txiter : all_conflicts) {
+            replaced.fee += txiter->GetModifiedFee();
+            replaced.size += txiter->GetTxSize();
+        }
+        // The total fee & size of the new diagram minus replaced fee & size should be the total
+        // fee & size of the old diagram minus replacement fee & size.
+        assert((first_sum - replaced) == (second_sum - FeeFrac{replacement_fees, replacement_vsize}));
+    }
+
+    // If internals report error, wrapper should too
+    auto err_tuple{ImprovesFeerateDiagram(pool, direct_conflicts, all_conflicts, replacement_fees, replacement_vsize)};
+    if (!calc_results.has_value()) {
+         assert(err_tuple.value().first == DiagramCheckError::UNCALCULABLE);
+    } else {
+        // Diagram check succeeded
+        auto old_sum = std::accumulate(calc_results->first.begin(), calc_results->first.end(), FeeFrac{});
+        auto new_sum = std::accumulate(calc_results->second.begin(), calc_results->second.end(), FeeFrac{});
+        if (!err_tuple.has_value()) {
+            // New diagram's final fee should always match or exceed old diagram's
+            assert(old_sum.fee <= new_sum.fee);
+        } else if (old_sum.fee > new_sum.fee) {
+            // Or it failed, and if old diagram had higher fees, it should be a failure
+            assert(err_tuple.value().first == DiagramCheckError::FAILURE);
+        }
+    }
+}