fix PING attack [CVE-2019-17048]

src/init.cpp

@@ -728,6 +728,22 @@ void ThreadImport(std::vector<boost::filesystem::path> vImportFiles)
     }
 }
 
+void ThreadNotifyRecentlyAdded()
+{
+    while (true) {
+        // Run the notifier on an integer second in the steady clock.
+        auto now = std::chrono::steady_clock::now().time_since_epoch();
+        auto nextFire = std::chrono::duration_cast<std::chrono::seconds>(
+            now + std::chrono::seconds(1));
+        std::this_thread::sleep_until(
+            std::chrono::time_point<std::chrono::steady_clock>(nextFire));
+
+        boost::this_thread::interruption_point();
+
+        mempool.NotifyRecentlyAdded();
+    }
+}
+
 /** Sanity checks
  *  Ensure that Bitcoin is running in a usable environment with all
  *  necessary library support.
@@ -1935,6 +1951,10 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
     LogPrintf("mapAddressBook.size() = %u\n",  pwalletMain ? pwalletMain->mapAddressBook.size() : 0);
 #endif
 
+    // Start the thread that notifies listeners of transactions that have been
+    // recently added to the mempool.
+    threadGroup.create_thread(boost::bind(&TraceThread<void (*)()>, "txnotify", &ThreadNotifyRecentlyAdded));
+
     if (GetBoolArg("-listenonion", DEFAULT_LISTEN_ONION))
         StartTorControl(threadGroup, scheduler);