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// Copyright (c) 2020-2022 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 <test/fuzz/fuzz.h>
#include <primitives/transaction.h>
#include <pubkey.h>
#include <script/interpreter.h>
#include <serialize.h>
#include <streams.h>
#include <univalue.h>
#include <util/strencodings.h>
#include <util/string.h>
#include <cstdint>
#include <string>
#include <vector>
// This fuzz "test" can be used to minimize test cases for script_assets_test in
// src/test/script_tests.cpp. While it written as a fuzz test, and can be used as such,
// fuzzing the inputs is unlikely to construct useful test cases.
//
// Instead, it is primarily intended to be run on a test set that was generated
// externally, for example using test/functional/feature_taproot.py's --dumptests mode.
// The minimized set can then be concatenated together, surrounded by '[' and ']',
// and used as the script_assets_test.json input to the script_assets_test unit test:
//
// (normal build)
// $ mkdir dump
// $ for N in $(seq 1 10); do TEST_DUMP_DIR=dump test/functional/feature_taproot.py --dumptests; done
// $ ...
//
// (libFuzzer build)
// $ mkdir dump-min
// $ FUZZ=script_assets_test_minimizer ./src/test/fuzz/fuzz -merge=1 -use_value_profile=1 dump-min/ dump/
// $ (echo -en '[\n'; cat dump-min/* | head -c -2; echo -en '\n]') >script_assets_test.json
namespace {
std::vector<unsigned char> CheckedParseHex(const std::string& str)
{
if (str.size() && !IsHex(str)) throw std::runtime_error("Non-hex input '" + str + "'");
return ParseHex(str);
}
CScript ScriptFromHex(const std::string& str)
{
std::vector<unsigned char> data = CheckedParseHex(str);
return CScript(data.begin(), data.end());
}
CMutableTransaction TxFromHex(const std::string& str)
{
CMutableTransaction tx;
try {
SpanReader{SER_DISK, SERIALIZE_TRANSACTION_NO_WITNESS, CheckedParseHex(str)} >> tx;
} catch (const std::ios_base::failure&) {
throw std::runtime_error("Tx deserialization failure");
}
return tx;
}
std::vector<CTxOut> TxOutsFromJSON(const UniValue& univalue)
{
if (!univalue.isArray()) throw std::runtime_error("Prevouts must be array");
std::vector<CTxOut> prevouts;
for (size_t i = 0; i < univalue.size(); ++i) {
CTxOut txout;
try {
SpanReader{SER_DISK, 0, CheckedParseHex(univalue[i].get_str())} >> txout;
} catch (const std::ios_base::failure&) {
throw std::runtime_error("Prevout invalid format");
}
prevouts.push_back(std::move(txout));
}
return prevouts;
}
CScriptWitness ScriptWitnessFromJSON(const UniValue& univalue)
{
if (!univalue.isArray()) throw std::runtime_error("Script witness is not array");
CScriptWitness scriptwitness;
for (size_t i = 0; i < univalue.size(); ++i) {
auto bytes = CheckedParseHex(univalue[i].get_str());
scriptwitness.stack.push_back(std::move(bytes));
}
return scriptwitness;
}
const std::map<std::string, unsigned int> FLAG_NAMES = {
{std::string("P2SH"), (unsigned int)SCRIPT_VERIFY_P2SH},
{std::string("DERSIG"), (unsigned int)SCRIPT_VERIFY_DERSIG},
{std::string("NULLDUMMY"), (unsigned int)SCRIPT_VERIFY_NULLDUMMY},
{std::string("CHECKLOCKTIMEVERIFY"), (unsigned int)SCRIPT_VERIFY_CHECKLOCKTIMEVERIFY},
{std::string("CHECKSEQUENCEVERIFY"), (unsigned int)SCRIPT_VERIFY_CHECKSEQUENCEVERIFY},
{std::string("WITNESS"), (unsigned int)SCRIPT_VERIFY_WITNESS},
{std::string("TAPROOT"), (unsigned int)SCRIPT_VERIFY_TAPROOT},
};
std::vector<unsigned int> AllFlags()
{
std::vector<unsigned int> ret;
for (unsigned int i = 0; i < 128; ++i) {
unsigned int flag = 0;
if (i & 1) flag |= SCRIPT_VERIFY_P2SH;
if (i & 2) flag |= SCRIPT_VERIFY_DERSIG;
if (i & 4) flag |= SCRIPT_VERIFY_NULLDUMMY;
if (i & 8) flag |= SCRIPT_VERIFY_CHECKLOCKTIMEVERIFY;
if (i & 16) flag |= SCRIPT_VERIFY_CHECKSEQUENCEVERIFY;
if (i & 32) flag |= SCRIPT_VERIFY_WITNESS;
if (i & 64) flag |= SCRIPT_VERIFY_TAPROOT;
// SCRIPT_VERIFY_WITNESS requires SCRIPT_VERIFY_P2SH
if (flag & SCRIPT_VERIFY_WITNESS && !(flag & SCRIPT_VERIFY_P2SH)) continue;
// SCRIPT_VERIFY_TAPROOT requires SCRIPT_VERIFY_WITNESS
if (flag & SCRIPT_VERIFY_TAPROOT && !(flag & SCRIPT_VERIFY_WITNESS)) continue;
ret.push_back(flag);
}
return ret;
}
const std::vector<unsigned int> ALL_FLAGS = AllFlags();
unsigned int ParseScriptFlags(const std::string& str)
{
if (str.empty()) return 0;
unsigned int flags = 0;
std::vector<std::string> words = SplitString(str, ',');
for (const std::string& word : words) {
auto it = FLAG_NAMES.find(word);
if (it == FLAG_NAMES.end()) throw std::runtime_error("Unknown verification flag " + word);
flags |= it->second;
}
return flags;
}
void Test(const std::string& str)
{
UniValue test;
if (!test.read(str) || !test.isObject()) throw std::runtime_error("Non-object test input");
CMutableTransaction tx = TxFromHex(test["tx"].get_str());
const std::vector<CTxOut> prevouts = TxOutsFromJSON(test["prevouts"]);
if (prevouts.size() != tx.vin.size()) throw std::runtime_error("Incorrect number of prevouts");
size_t idx = test["index"].getInt<int64_t>();
if (idx >= tx.vin.size()) throw std::runtime_error("Invalid index");
unsigned int test_flags = ParseScriptFlags(test["flags"].get_str());
bool final = test.exists("final") && test["final"].get_bool();
if (test.exists("success")) {
tx.vin[idx].scriptSig = ScriptFromHex(test["success"]["scriptSig"].get_str());
tx.vin[idx].scriptWitness = ScriptWitnessFromJSON(test["success"]["witness"]);
PrecomputedTransactionData txdata;
txdata.Init(tx, std::vector<CTxOut>(prevouts));
MutableTransactionSignatureChecker txcheck(&tx, idx, prevouts[idx].nValue, txdata, MissingDataBehavior::ASSERT_FAIL);
for (const auto flags : ALL_FLAGS) {
// "final": true tests are valid for all flags. Others are only valid with flags that are
// a subset of test_flags.
if (final || ((flags & test_flags) == flags)) {
(void)VerifyScript(tx.vin[idx].scriptSig, prevouts[idx].scriptPubKey, &tx.vin[idx].scriptWitness, flags, txcheck, nullptr);
}
}
}
if (test.exists("failure")) {
tx.vin[idx].scriptSig = ScriptFromHex(test["failure"]["scriptSig"].get_str());
tx.vin[idx].scriptWitness = ScriptWitnessFromJSON(test["failure"]["witness"]);
PrecomputedTransactionData txdata;
txdata.Init(tx, std::vector<CTxOut>(prevouts));
MutableTransactionSignatureChecker txcheck(&tx, idx, prevouts[idx].nValue, txdata, MissingDataBehavior::ASSERT_FAIL);
for (const auto flags : ALL_FLAGS) {
// If a test is supposed to fail with test_flags, it should also fail with any superset thereof.
if ((flags & test_flags) == test_flags) {
(void)VerifyScript(tx.vin[idx].scriptSig, prevouts[idx].scriptPubKey, &tx.vin[idx].scriptWitness, flags, txcheck, nullptr);
}
}
}
}
void test_init() {}
FUZZ_TARGET_INIT_HIDDEN(script_assets_test_minimizer, test_init, /*hidden=*/true)
{
if (buffer.size() < 2 || buffer.back() != '\n' || buffer[buffer.size() - 2] != ',') return;
const std::string str((const char*)buffer.data(), buffer.size() - 2);
try {
Test(str);
} catch (const std::runtime_error&) {
}
}
} // namespace
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