From 1023ef23b7bf6a65fb563f7ba33ed7a20b139e5e Mon Sep 17 00:00:00 2001
From: Adam Ierymenko <adam.ierymenko@gmail.com>
Date: Mon, 11 Jan 2016 09:06:10 -0800
Subject: Remove somewhat ugly and costly anti-recursion hack -- we will switch
 to more explicit methods.

---
 node/AntiRecursion.hpp | 135 -------------------------------------------------
 1 file changed, 135 deletions(-)
 delete mode 100644 node/AntiRecursion.hpp

(limited to 'node/AntiRecursion.hpp')

diff --git a/node/AntiRecursion.hpp b/node/AntiRecursion.hpp
deleted file mode 100644
index 78ee95c2..00000000
--- a/node/AntiRecursion.hpp
+++ /dev/null
@@ -1,135 +0,0 @@
-/*
- * 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_ANTIRECURSION_HPP
-#define ZT_ANTIRECURSION_HPP
-
-#include <string.h>
-#include <stdlib.h>
-
-#include "Constants.hpp"
-
-namespace ZeroTier {
-
-/**
- * Size of anti-recursion history
- */
-#define ZT_ANTIRECURSION_HISTORY_SIZE 16
-
-/**
- * Filter to prevent recursion (ZeroTier-over-ZeroTier)
- *
- * This works by logging ZeroTier packets that we send. It's then invoked
- * again against packets read from local Ethernet taps. If the last 32
- * bytes representing the ZeroTier packet match in the tap frame, then
- * the frame is a re-injection of a frame that we sent and is rejected.
- *
- * This means that ZeroTier packets simply will not traverse ZeroTier
- * networks, which would cause all sorts of weird problems.
- *
- * This is highly optimized code since it's checked for every packet.
- */
-class AntiRecursion
-{
-public:
-	AntiRecursion()
-	{
-		for(int i=0;i<ZT_ANTIRECURSION_HISTORY_SIZE;++i) {
-			_history[i].tail[0] = 0;
-			_history[i].tail[1] = 0;
-			_history[i].tail[2] = 0;
-			_history[i].tail[3] = 0;
-		}
-		_ptr = 0;
-	}
-
-	/**
-	 * Add an outgoing ZeroTier packet to the circular log
-	 *
-	 * @param data ZT packet data
-	 * @param len Length of packet
-	 */
-	inline void logOutgoingZT(const void *const data,const unsigned int len)
-	{
-		if (len < 32)
-			return;
-#ifdef ZT_NO_TYPE_PUNNING
-		memcpy(_history[++_ptr % ZT_ANTIRECURSION_HISTORY_SIZE].tail,reinterpret_cast<const uint8_t *>(data) + (len - 32),32);
-#else
-		uint64_t *t = _history[++_ptr % ZT_ANTIRECURSION_HISTORY_SIZE].tail;
-		const uint64_t *p = reinterpret_cast<const uint64_t *>(reinterpret_cast<const uint8_t *>(data) + (len - 32));
-		*(t++) = *(p++);
-		*(t++) = *(p++);
-		*(t++) = *(p++);
-		*t = *p;
-#endif
-	}
-
-	/**
-	 * Check an ethernet frame from a local tap against anti-recursion history
-	 *
-	 * @param data Raw frame data
-	 * @param len Length of frame
-	 * @return True if frame is OK to be passed, false if it's a ZT frame that we sent
-	 */
-	inline bool checkEthernetFrame(const void *const data,const unsigned int len) const
-	{
-		if (len < 32)
-			return true;
-		const uint8_t *const pp = reinterpret_cast<const uint8_t *>(data) + (len - 32);
-		const _ArItem *i = _history;
-		const _ArItem *const end = i + ZT_ANTIRECURSION_HISTORY_SIZE;
-		while (i != end) {
-#ifdef ZT_NO_TYPE_PUNNING
-			if (!memcmp(pp,i->tail,32)) {
-				return false;
-			}
-#else
-			const uint64_t *t = i->tail;
-			const uint64_t *p = reinterpret_cast<const uint64_t *>(pp);
-			uint64_t bits = *(t++) ^ *(p++);
-			bits |= *(t++) ^ *(p++);
-			bits |= *(t++) ^ *(p++);
-			bits |= *t ^ *p;
-			if (!bits) {
-				return false;
-			}
-#endif
-			++i;
-		}
-		return true;
-	}
-
-private:
-	struct _ArItem { uint64_t tail[4]; };
-	_ArItem _history[ZT_ANTIRECURSION_HISTORY_SIZE];
-	volatile unsigned long _ptr;
-};
-
-} // namespace ZeroTier
-
-#endif
-- 
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