tests: Add fuzzing harness for various CTxOut related functions

Author: practicalswift

src/Makefile.test.include

@@ -49,6 +49,7 @@ FUZZ_TARGETS = \
   test/fuzz/transaction \
   test/fuzz/tx_in \
   test/fuzz/tx_in_deserialize \
+  test/fuzz/tx_out \
   test/fuzz/txoutcompressor_deserialize \
   test/fuzz/txundo_deserialize
 
@@ -504,6 +505,12 @@ test_fuzz_tx_in_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 test_fuzz_tx_in_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
 test_fuzz_tx_in_LDADD = $(FUZZ_SUITE_LD_COMMON)
 
+test_fuzz_tx_out_SOURCES = $(FUZZ_SUITE) test/fuzz/tx_out.cpp
+test_fuzz_tx_out_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES)
+test_fuzz_tx_out_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
+test_fuzz_tx_out_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
+test_fuzz_tx_out_LDADD = $(FUZZ_SUITE_LD_COMMON)
+
 endif # ENABLE_FUZZ
 
 nodist_test_test_bitcoin_SOURCES = $(GENERATED_TEST_FILES)

src/test/fuzz/tx_out.cpp

@@ -0,0 +1,35 @@
+// Copyright (c) 2019 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 <consensus/validation.h>
+#include <core_memusage.h>
+#include <policy/policy.h>
+#include <primitives/transaction.h>
+#include <streams.h>
+#include <test/fuzz/fuzz.h>
+#include <version.h>
+
+void test_one_input(const std::vector<uint8_t>& buffer)
+{
+    CDataStream ds(buffer, SER_NETWORK, INIT_PROTO_VERSION);
+    CTxOut tx_out;
+    try {
+        int version;
+        ds >> version;
+        ds.SetVersion(version);
+        ds >> tx_out;
+    } catch (const std::ios_base::failure&) {
+        return;
+    }
+
+    const CFeeRate dust_relay_fee{DUST_RELAY_TX_FEE};
+    (void)GetDustThreshold(tx_out, dust_relay_fee);
+    (void)IsDust(tx_out, dust_relay_fee);
+    (void)RecursiveDynamicUsage(tx_out);
+
+    (void)tx_out.ToString();
+    (void)tx_out.IsNull();
+    tx_out.SetNull();
+    assert(tx_out.IsNull());
+}