master: prevent importing transaction with invalid TID

Else it leads to DB corruption and a crash of the master.

neo/master/transactions.py

@@ -282,11 +282,14 @@ class TransactionManager(EventQueue):
         if tid is None:
             # No TID requested, generate a temporary one
             tid = self._nextTID()
+        elif tid <= self._last_tid:
+            raise ProtocolError(
+                "new TID must be greater than the last committed one")
         else:
             # Use of specific TID requested, queue it immediately and update
             # last TID.
             self._queue.append(tid)
-            self.setLastTID(tid)
+            self._last_tid = tid
         txn = self._ttid_dict[tid] = Transaction(node, storage_readiness, tid)
         logging.debug('Begin %s', txn)
         return tid

neo/tests/threaded/test.py

@@ -2864,6 +2864,23 @@ class Test(NEOThreadedTest):
             self.assertRaises(RuntimeError, cluster.neoctl.setClusterState,
                               ClusterStates.STARTING_BACKUP)
 
+    @with_cluster()
+    def testTpcBeginWithInvalidTID(self, cluster):
+        storage = cluster.getZODBStorage()
+        txn = transaction.Transaction()
+        storage.tpc_begin(txn)
+        storage.store(ZERO_OID, None, 'foo', '', txn)
+        storage.tpc_vote(txn)
+        tid = storage.tpc_finish(txn)
+        self.assertRaises(NEOStorageError, storage.tpc_begin,
+                          transaction.Transaction(), tid)
+        new_tid = add64(tid, 1)
+        txn = transaction.Transaction()
+        storage.tpc_begin(txn, new_tid)
+        storage.store(ZERO_OID, tid, 'bar', '', txn)
+        storage.tpc_vote(txn)
+        self.assertEqual(add64(tid, 1), storage.tpc_finish(txn))
+
 
 if __name__ == "__main__":
     unittest.main()