tests: Add fuzzing harness for BanMan

src/Makefile.test.include

@@ -11,6 +11,7 @@ FUZZ_TARGETS = \
   test/fuzz/asmap \
   test/fuzz/asmap_direct \
   test/fuzz/banentry_deserialize \
+  test/fuzz/banman \
   test/fuzz/base_encode_decode \
   test/fuzz/bech32 \
   test/fuzz/block \
@@ -355,6 +356,12 @@ test_fuzz_banentry_deserialize_LDADD = $(FUZZ_SUITE_LD_COMMON)
 test_fuzz_banentry_deserialize_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
 test_fuzz_banentry_deserialize_SOURCES = test/fuzz/deserialize.cpp
 
+test_fuzz_banman_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES)
+test_fuzz_banman_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
+test_fuzz_banman_LDADD = $(FUZZ_SUITE_LD_COMMON)
+test_fuzz_banman_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
+test_fuzz_banman_SOURCES = test/fuzz/banman.cpp
+
 test_fuzz_base_encode_decode_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES)
 test_fuzz_base_encode_decode_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 test_fuzz_base_encode_decode_LDADD = $(FUZZ_SUITE_LD_COMMON)

src/test/fuzz/banman.cpp

@@ -0,0 +1,88 @@
+// 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 <banman.h>
+#include <fs.h>
+#include <netaddress.h>
+#include <test/fuzz/FuzzedDataProvider.h>
+#include <test/fuzz/fuzz.h>
+#include <test/fuzz/util.h>
+#include <util/system.h>
+
+#include <cstdint>
+#include <limits>
+#include <string>
+#include <vector>
+
+namespace {
+int64_t ConsumeBanTimeOffset(FuzzedDataProvider& fuzzed_data_provider) noexcept
+{
+    // Avoid signed integer overflow by capping to int32_t max:
+    // banman.cpp:137:73: runtime error: signed integer overflow: 1591700817 + 9223372036854775807 cannot be represented in type 'long'
+    return fuzzed_data_provider.ConsumeIntegralInRange<int64_t>(std::numeric_limits<int64_t>::min(), std::numeric_limits<int32_t>::max());
+}
+} // namespace
+
+void initialize()
+{
+    InitializeFuzzingContext();
+}
+
+void test_one_input(const std::vector<uint8_t>& buffer)
+{
+    FuzzedDataProvider fuzzed_data_provider{buffer.data(), buffer.size()};
+    const fs::path banlist_file = GetDataDir() / "fuzzed_banlist.dat";
+    fs::remove(banlist_file);
+    {
+        BanMan ban_man{banlist_file, nullptr, ConsumeBanTimeOffset(fuzzed_data_provider)};
+        while (fuzzed_data_provider.ConsumeBool()) {
+            switch (fuzzed_data_provider.ConsumeIntegralInRange<int>(0, 11)) {
+            case 0: {
+                ban_man.Ban(ConsumeNetAddr(fuzzed_data_provider),
+                    ConsumeBanTimeOffset(fuzzed_data_provider), fuzzed_data_provider.ConsumeBool());
+                break;
+            }
+            case 1: {
+                ban_man.Ban(ConsumeSubNet(fuzzed_data_provider),
+                    ConsumeBanTimeOffset(fuzzed_data_provider), fuzzed_data_provider.ConsumeBool());
+                break;
+            }
+            case 2: {
+                ban_man.ClearBanned();
+                break;
+            }
+            case 4: {
+                ban_man.IsBanned(ConsumeNetAddr(fuzzed_data_provider));
+                break;
+            }
+            case 5: {
+                ban_man.IsBanned(ConsumeSubNet(fuzzed_data_provider));
+                break;
+            }
+            case 6: {
+                ban_man.Unban(ConsumeNetAddr(fuzzed_data_provider));
+                break;
+            }
+            case 7: {
+                ban_man.Unban(ConsumeSubNet(fuzzed_data_provider));
+                break;
+            }
+            case 8: {
+                banmap_t banmap;
+                ban_man.GetBanned(banmap);
+                break;
+            }
+            case 9: {
+                ban_man.DumpBanlist();
+                break;
+            }
+            case 11: {
+                ban_man.Discourage(ConsumeNetAddr(fuzzed_data_provider));
+                break;
+            }
+            }
+        }
+    }
+    fs::remove(banlist_file);
+}

src/test/fuzz/util.h

@@ -8,9 +8,11 @@
 #include <amount.h>
 #include <arith_uint256.h>
 #include <attributes.h>
+#include <chainparamsbase.h>
 #include <coins.h>
 #include <consensus/consensus.h>
 #include <netaddress.h>
+#include <netbase.h>
 #include <primitives/transaction.h>
 #include <script/script.h>
 #include <script/standard.h>
@@ -18,6 +20,7 @@
 #include <streams.h>
 #include <test/fuzz/FuzzedDataProvider.h>
 #include <test/fuzz/fuzz.h>
+#include <test/util/setup_common.h>
 #include <txmempool.h>
 #include <uint256.h>
 #include <version.h>
@@ -256,4 +259,9 @@ CSubNet ConsumeSubNet(FuzzedDataProvider& fuzzed_data_provider) noexcept
     return {ConsumeNetAddr(fuzzed_data_provider), fuzzed_data_provider.ConsumeIntegral<int32_t>()};
 }
 
+void InitializeFuzzingContext(const std::string& chain_name = CBaseChainParams::REGTEST)
+{
+    static const BasicTestingSetup basic_testing_setup{chain_name, {"-nodebuglogfile"}};
+}
+
 #endif // BITCOIN_TEST_FUZZ_UTIL_H