From 0a573682f24d20cb178b8b6f97c35ec46901c4db Mon Sep 17 00:00:00 2001
From: practicalswift <practicalswift@users.noreply.github.com>
Date: Tue, 8 Oct 2019 09:33:53 +0000
Subject: tests: Add fuzzing harness for CheckTransaction(...),
 IsStandardTx(...) and other CTransaction related functions

---
 src/Makefile.test.include     |  8 +++++
 src/test/fuzz/transaction.cpp | 81 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 89 insertions(+)
 create mode 100644 src/test/fuzz/transaction.cpp

diff --git a/src/Makefile.test.include b/src/Makefile.test.include
index d3fe138133..698bcaac78 100644
--- a/src/Makefile.test.include
+++ b/src/Makefile.test.include
@@ -22,6 +22,7 @@ FUZZ_TARGETS = \
   test/fuzz/netaddr_deserialize \
   test/fuzz/script_flags \
   test/fuzz/service_deserialize \
+  test/fuzz/transaction \
   test/fuzz/transaction_deserialize \
   test/fuzz/txoutcompressor_deserialize \
   test/fuzz/txundo_deserialize
@@ -321,6 +322,13 @@ test_fuzz_blocktransactionsrequest_deserialize_CPPFLAGS = $(AM_CPPFLAGS) $(BITCO
 test_fuzz_blocktransactionsrequest_deserialize_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 test_fuzz_blocktransactionsrequest_deserialize_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
 test_fuzz_blocktransactionsrequest_deserialize_LDADD = $(FUZZ_SUITE_LD_COMMON)
+
+test_fuzz_transaction_SOURCES = $(FUZZ_SUITE) test/fuzz/transaction.cpp
+test_fuzz_transaction_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES)
+test_fuzz_transaction_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
+test_fuzz_transaction_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
+test_fuzz_transaction_LDADD = $(FUZZ_SUITE_LD_COMMON)
+
 endif # ENABLE_FUZZ
 
 nodist_test_test_bitcoin_SOURCES = $(GENERATED_TEST_FILES)
diff --git a/src/test/fuzz/transaction.cpp b/src/test/fuzz/transaction.cpp
new file mode 100644
index 0000000000..96d7947b07
--- /dev/null
+++ b/src/test/fuzz/transaction.cpp
@@ -0,0 +1,81 @@
+// 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 <coins.h>
+#include <consensus/tx_check.h>
+#include <consensus/tx_verify.h>
+#include <consensus/validation.h>
+#include <core_io.h>
+#include <core_memusage.h>
+#include <policy/policy.h>
+#include <policy/settings.h>
+#include <primitives/transaction.h>
+#include <streams.h>
+#include <test/fuzz/fuzz.h>
+#include <util/rbf.h>
+#include <validation.h>
+#include <version.h>
+
+#include <cassert>
+
+void test_one_input(const std::vector<uint8_t>& buffer)
+{
+    CDataStream ds(buffer, SER_NETWORK, INIT_PROTO_VERSION);
+    try {
+        int nVersion;
+        ds >> nVersion;
+        ds.SetVersion(nVersion);
+    } catch (const std::ios_base::failure& e) {
+        return;
+    }
+    bool valid = true;
+    const CTransaction tx = [&] {
+        try {
+            return CTransaction(deserialize, ds);
+        } catch (const std::ios_base::failure& e) {
+            valid = false;
+            return CTransaction();
+        }
+    }();
+    if (!valid) {
+        return;
+    }
+
+    CValidationState state_with_dupe_check;
+    const bool valid_with_dupe_check = CheckTransaction(tx, state_with_dupe_check, /* fCheckDuplicateInputs= */ true);
+    CValidationState state_without_dupe_check;
+    const bool valid_without_dupe_check = CheckTransaction(tx, state_without_dupe_check, /* fCheckDuplicateInputs= */ false);
+    if (valid_with_dupe_check) {
+        assert(valid_without_dupe_check);
+    }
+
+    const CFeeRate dust_relay_fee{DUST_RELAY_TX_FEE};
+    std::string reason;
+    const bool is_standard_with_permit_bare_multisig = IsStandardTx(tx, /* permit_bare_multisig= */ true, dust_relay_fee, reason);
+    const bool is_standard_without_permit_bare_multisig = IsStandardTx(tx, /* permit_bare_multisig= */ false, dust_relay_fee, reason);
+    if (is_standard_without_permit_bare_multisig) {
+        assert(is_standard_with_permit_bare_multisig);
+    }
+
+    (void)tx.GetHash();
+    (void)tx.GetTotalSize();
+    try {
+        (void)tx.GetValueOut();
+    } catch (const std::runtime_error&) {
+    }
+    (void)tx.GetWitnessHash();
+    (void)tx.HasWitness();
+    (void)tx.IsCoinBase();
+    (void)tx.IsNull();
+    (void)tx.ToString();
+
+    (void)EncodeHexTx(tx);
+    (void)GetLegacySigOpCount(tx);
+    (void)GetTransactionWeight(tx);
+    (void)GetVirtualTransactionSize(tx);
+    (void)IsFinalTx(tx, /* nBlockHeight= */ 1024, /* nBlockTime= */ 1024);
+    (void)IsStandardTx(tx, reason);
+    (void)RecursiveDynamicUsage(tx);
+    (void)SignalsOptInRBF(tx);
+}
-- 
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