1 files changed, 38 insertions, 4 deletions

diff --git a/src/test/fuzz/banman.cpp b/src/test/fuzz/banman.cpp
index 759a70a857..85a2ac990c 100644
--- a/src/test/fuzz/banman.cpp
+++ b/src/test/fuzz/banman.cpp
@@ -9,8 +9,10 @@
 #include <test/fuzz/fuzz.h>
 #include <test/fuzz/util.h>
 #include <test/util/setup_common.h>
+#include <util/readwritefile.h>
 #include <util/system.h>
 
+#include <cassert>
 #include <cstdint>
 #include <limits>
 #include <string>
@@ -30,6 +32,13 @@ void initialize_banman()
     static const auto testing_setup = MakeNoLogFileContext<>();
 }
 
+static bool operator==(const CBanEntry& lhs, const CBanEntry& rhs)
+{
+    return lhs.nVersion == rhs.nVersion &&
+           lhs.nCreateTime == rhs.nCreateTime &&
+           lhs.nBanUntil == rhs.nBanUntil;
+}
+
 FUZZ_TARGET_INIT(banman, initialize_banman)
 {
     // The complexity is O(N^2), where N is the input size, because each call
@@ -38,10 +47,23 @@ FUZZ_TARGET_INIT(banman, initialize_banman)
     int limit_max_ops{300};
     FuzzedDataProvider fuzzed_data_provider{buffer.data(), buffer.size()};
     SetMockTime(ConsumeTime(fuzzed_data_provider));
-    const fs::path banlist_file = gArgs.GetDataDirNet() / "fuzzed_banlist.dat";
-    fs::remove(banlist_file);
+    fs::path banlist_file = gArgs.GetDataDirNet() / "fuzzed_banlist";
+
+    const bool start_with_corrupted_banlist{fuzzed_data_provider.ConsumeBool()};
+    bool force_read_and_write_to_err{false};
+    if (start_with_corrupted_banlist) {
+        const std::string sfx{fuzzed_data_provider.ConsumeBool() ? ".dat" : ".json"};
+        assert(WriteBinaryFile(banlist_file.string() + sfx,
+                               fuzzed_data_provider.ConsumeRandomLengthString()));
+    } else {
+        force_read_and_write_to_err = fuzzed_data_provider.ConsumeBool();
+        if (force_read_and_write_to_err) {
+            banlist_file = fs::path{"path"} / "to" / "inaccessible" / "fuzzed_banlist";
+        }
+    }
+
     {
-        BanMan ban_man{banlist_file, nullptr, ConsumeBanTimeOffset(fuzzed_data_provider)};
+        BanMan ban_man{banlist_file, /* client_interface */ nullptr, /* default_ban_time */ ConsumeBanTimeOffset(fuzzed_data_provider)};
         while (--limit_max_ops >= 0 && fuzzed_data_provider.ConsumeBool()) {
             CallOneOf(
                 fuzzed_data_provider,
@@ -79,6 +101,18 @@ FUZZ_TARGET_INIT(banman, initialize_banman)
                     ban_man.Discourage(ConsumeNetAddr(fuzzed_data_provider));
                 });
         }
+        if (!force_read_and_write_to_err) {
+            ban_man.DumpBanlist();
+            SetMockTime(ConsumeTime(fuzzed_data_provider));
+            banmap_t banmap;
+            ban_man.GetBanned(banmap);
+            BanMan ban_man_read{banlist_file, /* client_interface */ nullptr, /* default_ban_time */ 0};
+            banmap_t banmap_read;
+            ban_man_read.GetBanned(banmap_read);
+            // Temporarily disabled to allow the remainder of the fuzz test to run while a fix is being worked on:
+            // assert(banmap == banmap_read);
+        }
     }
-    fs::remove(banlist_file);
+    fs::remove(banlist_file.string() + ".dat");
+    fs::remove(banlist_file.string() + ".json");
 }