From 8ef4edebbfeead53e5b2b454086e21e42e809aab Mon Sep 17 00:00:00 2001
From: Adam Ierymenko <adam.ierymenko@gmail.com>
Date: Thu, 5 Nov 2015 12:22:58 -0800
Subject: Deferred decode for HELLO to prevent HELLOcalypse under high load of
 new peers.

---
 node/BinarySemaphore.hpp | 106 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 106 insertions(+)
 create mode 100644 node/BinarySemaphore.hpp

(limited to 'node/BinarySemaphore.hpp')

diff --git a/node/BinarySemaphore.hpp b/node/BinarySemaphore.hpp
new file mode 100644
index 00000000..97d0d1c4
--- /dev/null
+++ b/node/BinarySemaphore.hpp
@@ -0,0 +1,106 @@
+/*
+ * ZeroTier One - Network Virtualization Everywhere
+ * Copyright (C) 2011-2015  ZeroTier, Inc.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * --
+ *
+ * ZeroTier may be used and distributed under the terms of the GPLv3, which
+ * are available at: http://www.gnu.org/licenses/gpl-3.0.html
+ *
+ * If you would like to embed ZeroTier into a commercial application or
+ * redistribute it in a modified binary form, please contact ZeroTier Networks
+ * LLC. Start here: http://www.zerotier.com/
+ */
+
+#ifndef ZT_BINARYSEMAPHORE_HPP
+#define ZT_BINARYSEMAPHORE_HPP
+
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+#include "Constants.hpp"
+#include "NonCopyable.hpp"
+
+#ifdef __WINDOWS__
+
+#include <Windows.h>
+
+namespace ZeroTier {
+
+class BinarySemaphore : NonCopyable
+{
+public:
+	BinarySemaphore() throw() { _sem = CreateSemaphore(NULL,0,1,NULL); }
+	~BinarySemaphore() { CloseHandle(_sem); }
+	inline void wait() { WaitForSingleObject(_sem,INFINITE); }
+	inline void post() { ReleaseSemaphore(_sem,1,NULL); }
+private:
+	HANDLE _sem;
+};
+
+} // namespace ZeroTier
+
+#else // !__WINDOWS__
+
+#include <pthread.h>
+
+namespace ZeroTier {
+
+class BinarySemaphore : NonCopyable
+{
+public:
+	BinarySemaphore()
+	{
+		pthread_mutex_init(&_mh,(const pthread_mutexattr_t *)0);
+		pthread_cond_init(&_cond,(const pthread_condattr_t *)0);
+		_f = false;
+	}
+
+	~BinarySemaphore()
+	{
+		pthread_cond_destroy(&_cond);
+		pthread_mutex_destroy(&_mh);
+	}
+
+	inline void wait()
+	{
+		pthread_mutex_lock(const_cast <pthread_mutex_t *>(&_mh));
+		while (!_f)
+			pthread_cond_wait(const_cast <pthread_cond_t *>(&_cond),const_cast <pthread_mutex_t *>(&_mh));
+		_f = false;
+		pthread_mutex_unlock(const_cast <pthread_mutex_t *>(&_mh));
+	}
+
+	inline void post()
+	{
+		pthread_mutex_lock(const_cast <pthread_mutex_t *>(&_mh));
+		_f = true;
+		pthread_mutex_unlock(const_cast <pthread_mutex_t *>(&_mh));
+		pthread_cond_signal(const_cast <pthread_cond_t *>(&_cond));
+	}
+
+private:
+	pthread_cond_t _cond;
+	pthread_mutex_t _mh;
+	volatile bool _f;
+};
+
+} // namespace ZeroTier
+
+#endif // !__WINDOWS__
+
+#endif
-- 
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