tests: Add fuzzing harness for classes/functions in cuckoocache.h

src/Makefile.test.include

@@ -30,6 +30,7 @@ FUZZ_TARGETS = \
   test/fuzz/chain \
   test/fuzz/checkqueue \
   test/fuzz/coins_deserialize \
+  test/fuzz/cuckoocache \
   test/fuzz/decode_tx \
   test/fuzz/descriptor_parse \
   test/fuzz/diskblockindex_deserialize \
@@ -444,6 +445,12 @@ test_fuzz_coins_deserialize_LDADD = $(FUZZ_SUITE_LD_COMMON)
 test_fuzz_coins_deserialize_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
 test_fuzz_coins_deserialize_SOURCES = test/fuzz/deserialize.cpp
 
+test_fuzz_cuckoocache_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES)
+test_fuzz_cuckoocache_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
+test_fuzz_cuckoocache_LDADD = $(FUZZ_SUITE_LD_COMMON)
+test_fuzz_cuckoocache_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
+test_fuzz_cuckoocache_SOURCES = test/fuzz/cuckoocache.cpp
+
 test_fuzz_decode_tx_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES)
 test_fuzz_decode_tx_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 test_fuzz_decode_tx_LDADD = $(FUZZ_SUITE_LD_COMMON)

src/cuckoocache.h

@@ -5,6 +5,7 @@
 #ifndef BITCOIN_CUCKOOCACHE_H
 #define BITCOIN_CUCKOOCACHE_H
 
+#include <algorithm> // std::find
 #include <array>
 #include <atomic>
 #include <cmath>

src/test/fuzz/cuckoocache.cpp

@@ -0,0 +1,49 @@
+// Copyright (c) 2020 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <cuckoocache.h>
+#include <optional.h>
+#include <script/sigcache.h>
+#include <test/fuzz/FuzzedDataProvider.h>
+#include <test/fuzz/fuzz.h>
+#include <test/fuzz/util.h>
+#include <test/util/setup_common.h>
+
+#include <cstdint>
+#include <string>
+#include <vector>
+
+namespace {
+FuzzedDataProvider* fuzzed_data_provider_ptr = nullptr;
+
+struct RandomHasher {
+    template <uint8_t>
+    uint32_t operator()(const bool& /* unused */) const
+    {
+        assert(fuzzed_data_provider_ptr != nullptr);
+        return fuzzed_data_provider_ptr->ConsumeIntegral<uint32_t>();
+    }
+};
+} // namespace
+
+void test_one_input(const std::vector<uint8_t>& buffer)
+{
+    FuzzedDataProvider fuzzed_data_provider(buffer.data(), buffer.size());
+    fuzzed_data_provider_ptr = &fuzzed_data_provider;
+    CuckooCache::cache<bool, RandomHasher> cuckoo_cache{};
+    if (fuzzed_data_provider.ConsumeBool()) {
+        const size_t megabytes = fuzzed_data_provider.ConsumeIntegralInRange<size_t>(0, 16);
+        cuckoo_cache.setup_bytes(megabytes << 20);
+    } else {
+        cuckoo_cache.setup(fuzzed_data_provider.ConsumeIntegralInRange<uint32_t>(0, 4096));
+    }
+    while (fuzzed_data_provider.ConsumeBool()) {
+        if (fuzzed_data_provider.ConsumeBool()) {
+            cuckoo_cache.insert(fuzzed_data_provider.ConsumeBool());
+        } else {
+            cuckoo_cache.contains(fuzzed_data_provider.ConsumeBool(), fuzzed_data_provider.ConsumeBool());
+        }
+    }
+    fuzzed_data_provider_ptr = nullptr;
+}