1  // Copyright (c) 2013-2022 The Bitcoin Core developers
  2  // Distributed under the MIT software license, see the accompanying
  3  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  4  
  5  #include <common/system.h>
  6  #include <consensus/tx_check.h>
  7  #include <consensus/validation.h>
  8  #include <hash.h>
  9  #include <script/interpreter.h>
 10  #include <script/script.h>
 11  #include <serialize.h>
 12  #include <streams.h>
 13  #include <test/data/sighash.json.h>
 14  #include <test/util/json.h>
 15  #include <test/util/random.h>
 16  #include <test/util/setup_common.h>
 17  #include <util/strencodings.h>
 18  
 19  #include <iostream>
 20  
 21  #include <boost/test/unit_test.hpp>
 22  
 23  #include <univalue.h>
 24  
 25  // Old script.cpp SignatureHash function
 26  uint256 static SignatureHashOld(CScript scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType)
 27  {
 28      if (nIn >= txTo.vin.size())
 29      {
 30          return uint256::ONE;
 31      }
 32      CMutableTransaction txTmp(txTo);
 33  
 34      // In case concatenating two scripts ends up with two codeseparators,
 35      // or an extra one at the end, this prevents all those possible incompatibilities.
 36      FindAndDelete(scriptCode, CScript(OP_CODESEPARATOR));
 37  
 38      // Blank out other inputs' signatures
 39      for (unsigned int i = 0; i < txTmp.vin.size(); i++)
 40          txTmp.vin[i].scriptSig = CScript();
 41      txTmp.vin[nIn].scriptSig = scriptCode;
 42  
 43      // Blank out some of the outputs
 44      if ((nHashType & 0x1f) == SIGHASH_NONE)
 45      {
 46          // Wildcard payee
 47          txTmp.vout.clear();
 48  
 49          // Let the others update at will
 50          for (unsigned int i = 0; i < txTmp.vin.size(); i++)
 51              if (i != nIn)
 52                  txTmp.vin[i].nSequence = 0;
 53      }
 54      else if ((nHashType & 0x1f) == SIGHASH_SINGLE)
 55      {
 56          // Only lock-in the txout payee at same index as txin
 57          unsigned int nOut = nIn;
 58          if (nOut >= txTmp.vout.size())
 59          {
 60              return uint256::ONE;
 61          }
 62          txTmp.vout.resize(nOut+1);
 63          for (unsigned int i = 0; i < nOut; i++)
 64              txTmp.vout[i].SetNull();
 65  
 66          // Let the others update at will
 67          for (unsigned int i = 0; i < txTmp.vin.size(); i++)
 68              if (i != nIn)
 69                  txTmp.vin[i].nSequence = 0;
 70      }
 71  
 72      // Blank out other inputs completely, not recommended for open transactions
 73      if (nHashType & SIGHASH_ANYONECANPAY)
 74      {
 75          txTmp.vin[0] = txTmp.vin[nIn];
 76          txTmp.vin.resize(1);
 77      }
 78  
 79      // Serialize and hash
 80      HashWriter ss{};
 81      ss << TX_NO_WITNESS(txTmp) << nHashType;
 82      return ss.GetHash();
 83  }
 84  
 85  struct SigHashTest : BasicTestingSetup {
 86  void RandomScript(CScript &script) {
 87      static const opcodetype oplist[] = {OP_FALSE, OP_1, OP_2, OP_3, OP_CHECKSIG, OP_IF, OP_VERIF, OP_RETURN, OP_CODESEPARATOR};
 88      script = CScript();
 89      int ops = (m_rng.randrange(10));
 90      for (int i=0; i<ops; i++)
 91          script << oplist[m_rng.randrange(std::size(oplist))];
 92  }
 93  
 94  void RandomTransaction(CMutableTransaction& tx, bool fSingle)
 95  {
 96      tx.version = m_rng.rand32();
 97      tx.vin.clear();
 98      tx.vout.clear();
 99      tx.nLockTime = (m_rng.randbool()) ? m_rng.rand32() : 0;
100      int ins = (m_rng.randbits(2)) + 1;
101      int outs = fSingle ? ins : (m_rng.randbits(2)) + 1;
102      for (int in = 0; in < ins; in++) {
103          tx.vin.emplace_back();
104          CTxIn &txin = tx.vin.back();
105          txin.prevout.hash = Txid::FromUint256(m_rng.rand256());
106          txin.prevout.n = m_rng.randbits(2);
107          RandomScript(txin.scriptSig);
108          txin.nSequence = (m_rng.randbool()) ? m_rng.rand32() : std::numeric_limits<uint32_t>::max();
109      }
110      for (int out = 0; out < outs; out++) {
111          tx.vout.emplace_back();
112          CTxOut &txout = tx.vout.back();
113          txout.nValue = RandMoney(m_rng);
114          RandomScript(txout.scriptPubKey);
115      }
116  }
117  }; // struct SigHashTest
118  
119  BOOST_FIXTURE_TEST_SUITE(sighash_tests, SigHashTest)
120  
121  BOOST_AUTO_TEST_CASE(sighash_test)
122  {
123      #if defined(PRINT_SIGHASH_JSON)
124      std::cout << "[\n";
125      std::cout << "\t[\"raw_transaction, script, input_index, hashType, signature_hash (result)\"],\n";
126      int nRandomTests = 500;
127      #else
128      int nRandomTests = 50000;
129      #endif
130      for (int i=0; i<nRandomTests; i++) {
131          int nHashType{int(m_rng.rand32())};
132          CMutableTransaction txTo;
133          RandomTransaction(txTo, (nHashType & 0x1f) == SIGHASH_SINGLE);
134          CScript scriptCode;
135          RandomScript(scriptCode);
136          int nIn = m_rng.randrange(txTo.vin.size());
137  
138          uint256 sh, sho;
139          sho = SignatureHashOld(scriptCode, CTransaction(txTo), nIn, nHashType);
140          sh = SignatureHash(scriptCode, txTo, nIn, nHashType, 0, SigVersion::BASE);
141          #if defined(PRINT_SIGHASH_JSON)
142          DataStream ss;
143          ss << TX_WITH_WITNESS(txTo);
144  
145          std::cout << "\t[\"" ;
146          std::cout << HexStr(ss) << "\", \"";
147          std::cout << HexStr(scriptCode) << "\", ";
148          std::cout << nIn << ", ";
149          std::cout << nHashType << ", \"";
150          std::cout << sho.GetHex() << "\"]";
151          if (i+1 != nRandomTests) {
152            std::cout << ",";
153          }
154          std::cout << "\n";
155          #endif
156          BOOST_CHECK(sh == sho);
157      }
158      #if defined(PRINT_SIGHASH_JSON)
159      std::cout << "]\n";
160      #endif
161  }
162  
163  // Goal: check that SignatureHash generates correct hash
164  BOOST_AUTO_TEST_CASE(sighash_from_data)
165  {
166      UniValue tests = read_json(json_tests::sighash);
167  
168      for (unsigned int idx = 0; idx < tests.size(); idx++) {
169          const UniValue& test = tests[idx];
170          std::string strTest = test.write();
171          if (test.size() < 1) // Allow for extra stuff (useful for comments)
172          {
173              BOOST_ERROR("Bad test: " << strTest);
174              continue;
175          }
176          if (test.size() == 1) continue; // comment
177  
178          std::string raw_tx, raw_script, sigHashHex;
179          int nIn, nHashType;
180          uint256 sh;
181          CTransactionRef tx;
182          CScript scriptCode = CScript();
183  
184          try {
185            // deserialize test data
186            raw_tx = test[0].get_str();
187            raw_script = test[1].get_str();
188            nIn = test[2].getInt<int>();
189            nHashType = test[3].getInt<int>();
190            sigHashHex = test[4].get_str();
191  
192            DataStream stream(ParseHex(raw_tx));
193            stream >> TX_WITH_WITNESS(tx);
194  
195            TxValidationState state;
196            BOOST_CHECK_MESSAGE(CheckTransaction(*tx, state), strTest);
197            BOOST_CHECK(state.IsValid());
198  
199            std::vector<unsigned char> raw = ParseHex(raw_script);
200            scriptCode.insert(scriptCode.end(), raw.begin(), raw.end());
201          } catch (...) {
202            BOOST_ERROR("Bad test, couldn't deserialize data: " << strTest);
203            continue;
204          }
205  
206          sh = SignatureHash(scriptCode, *tx, nIn, nHashType, 0, SigVersion::BASE);
207          BOOST_CHECK_MESSAGE(sh.GetHex() == sigHashHex, strTest);
208      }
209  }
210  
211  BOOST_AUTO_TEST_CASE(sighash_caching)
212  {
213      // Get a script, transaction and parameters as inputs to the sighash function.
214      CScript scriptcode;
215      RandomScript(scriptcode);
216      CScript diff_scriptcode{scriptcode};
217      diff_scriptcode << OP_1;
218      CMutableTransaction tx;
219      RandomTransaction(tx, /*fSingle=*/false);
220      const auto in_index{static_cast<uint32_t>(m_rng.randrange(tx.vin.size()))};
221      const auto amount{m_rng.rand<CAmount>()};
222  
223      // Exercise the sighash function under both legacy and segwit v0.
224      for (const auto sigversion: {SigVersion::BASE, SigVersion::WITNESS_V0}) {
225          // For each, run it against all the 6 standard hash types and a few additional random ones.
226          std::vector<int32_t> hash_types{{SIGHASH_ALL, SIGHASH_SINGLE, SIGHASH_NONE, SIGHASH_ALL | SIGHASH_ANYONECANPAY,
227                                            SIGHASH_SINGLE | SIGHASH_ANYONECANPAY, SIGHASH_NONE | SIGHASH_ANYONECANPAY,
228                                            SIGHASH_ANYONECANPAY, 0, std::numeric_limits<int32_t>::max()}};
229          for (int i{0}; i < 10; ++i) {
230              hash_types.push_back(i % 2 == 0 ? m_rng.rand<int8_t>() : m_rng.rand<int32_t>());
231          }
232  
233          // Reuse the same cache across script types. This must not cause any issue as the cached value for one hash type must never
234          // be confused for another (instantiating the cache within the loop instead would prevent testing this).
235          SigHashCache cache;
236          for (const auto hash_type: hash_types) {
237              const bool expect_one{sigversion == SigVersion::BASE && ((hash_type & 0x1f) == SIGHASH_SINGLE) && in_index >= tx.vout.size()};
238  
239              // The result of computing the sighash should be the same with or without cache.
240              const auto sighash_with_cache{SignatureHash(scriptcode, tx, in_index, hash_type, amount, sigversion, nullptr, &cache)};
241              const auto sighash_no_cache{SignatureHash(scriptcode, tx, in_index, hash_type, amount, sigversion, nullptr, nullptr)};
242              BOOST_CHECK_EQUAL(sighash_with_cache, sighash_no_cache);
243  
244              // Calling the cached version again should return the same value again.
245              BOOST_CHECK_EQUAL(sighash_with_cache, SignatureHash(scriptcode, tx, in_index, hash_type, amount, sigversion, nullptr, &cache));
246  
247              // While here we might as well also check that the result for legacy is the same as for the old SignatureHash() function.
248              if (sigversion == SigVersion::BASE) {
249                  BOOST_CHECK_EQUAL(sighash_with_cache, SignatureHashOld(scriptcode, CTransaction(tx), in_index, hash_type));
250              }
251  
252              // Calling with a different scriptcode (for instance in case a CODESEP is encountered) will not return the cache value but
253              // overwrite it. The sighash will always be different except in case of legacy SIGHASH_SINGLE bug.
254              const auto sighash_with_cache2{SignatureHash(diff_scriptcode, tx, in_index, hash_type, amount, sigversion, nullptr, &cache)};
255              const auto sighash_no_cache2{SignatureHash(diff_scriptcode, tx, in_index, hash_type, amount, sigversion, nullptr, nullptr)};
256              BOOST_CHECK_EQUAL(sighash_with_cache2, sighash_no_cache2);
257              if (!expect_one) {
258                  BOOST_CHECK_NE(sighash_with_cache, sighash_with_cache2);
259              } else {
260                  BOOST_CHECK_EQUAL(sighash_with_cache, sighash_with_cache2);
261                  BOOST_CHECK_EQUAL(sighash_with_cache, uint256::ONE);
262              }
263  
264              // Calling the cached version again should return the same value again.
265              BOOST_CHECK_EQUAL(sighash_with_cache2, SignatureHash(diff_scriptcode, tx, in_index, hash_type, amount, sigversion, nullptr, &cache));
266  
267              // And if we store a different value for this scriptcode and hash type it will return that instead.
268              {
269                  HashWriter h{};
270                  h << 42;
271                  cache.Store(hash_type, scriptcode, h);
272                  const auto stored_hash{h.GetHash()};
273                  BOOST_CHECK(cache.Load(hash_type, scriptcode, h));
274                  const auto loaded_hash{h.GetHash()};
275                  BOOST_CHECK_EQUAL(stored_hash, loaded_hash);
276              }
277  
278              // And using this mutated cache with the sighash function will return the new value (except in the legacy SIGHASH_SINGLE bug
279              // case in which it'll return 1).
280              if (!expect_one) {
281                  BOOST_CHECK_NE(SignatureHash(scriptcode, tx, in_index, hash_type, amount, sigversion, nullptr, &cache), sighash_with_cache);
282                  HashWriter h{};
283                  BOOST_CHECK(cache.Load(hash_type, scriptcode, h));
284                  h << hash_type;
285                  const auto new_hash{h.GetHash()};
286                  BOOST_CHECK_EQUAL(SignatureHash(scriptcode, tx, in_index, hash_type, amount, sigversion, nullptr, &cache), new_hash);
287              } else {
288                  BOOST_CHECK_EQUAL(SignatureHash(scriptcode, tx, in_index, hash_type, amount, sigversion, nullptr, &cache), uint256::ONE);
289              }
290  
291              // Wipe the cache and restore the correct cached value for this scriptcode and hash_type before starting the next iteration.
292              HashWriter dummy{};
293              cache.Store(hash_type, diff_scriptcode, dummy);
294              (void)SignatureHash(scriptcode, tx, in_index, hash_type, amount, sigversion, nullptr, &cache);
295              BOOST_CHECK(cache.Load(hash_type, scriptcode, dummy) || expect_one);
296          }
297      }
298  }
299  
300  BOOST_AUTO_TEST_SUITE_END()