mirror of
https://github.com/zerotier/ZeroTierOne.git
synced 2024-12-19 13:07:55 +00:00
111 lines
3.2 KiB
C++
111 lines
3.2 KiB
C++
/*
|
|
* ZeroTier One - Global Peer to Peer Ethernet
|
|
* Copyright (C) 2011-2014 ZeroTier Networks LLC
|
|
*
|
|
* 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 {
|
|
|
|
#define ZT_ANTIRECURSION_TAIL_LEN 256
|
|
|
|
/**
|
|
* 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 N
|
|
* 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.
|
|
*
|
|
* NOTE: this is applied to low-level packets before they are sent to
|
|
* SocketManager and/or sockets, not to fully assembled packets before
|
|
* (possible) fragmentation.
|
|
*/
|
|
class AntiRecursion
|
|
{
|
|
public:
|
|
AntiRecursion()
|
|
throw()
|
|
{
|
|
memset(_history,0,sizeof(_history));
|
|
_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 *data,unsigned int len)
|
|
throw()
|
|
{
|
|
ArItem *i = &(_history[_ptr++ % ZT_ANTIRECURSION_HISTORY_SIZE]);
|
|
const unsigned int tl = (len > ZT_ANTIRECURSION_TAIL_LEN) ? ZT_ANTIRECURSION_TAIL_LEN : len;
|
|
memcpy(i->tail,((const unsigned char *)data) + (len - tl),tl);
|
|
i->len = tl;
|
|
}
|
|
|
|
/**
|
|
* 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 *data,unsigned int len)
|
|
throw()
|
|
{
|
|
for(unsigned int h=0;h<ZT_ANTIRECURSION_HISTORY_SIZE;++h) {
|
|
ArItem *i = &(_history[h]);
|
|
if ((len >= i->len)&&(!memcmp(((const unsigned char *)data) + (len - i->len),i->tail,i->len)))
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
private:
|
|
struct ArItem
|
|
{
|
|
unsigned char tail[ZT_ANTIRECURSION_TAIL_LEN];
|
|
unsigned int len;
|
|
};
|
|
ArItem _history[ZT_ANTIRECURSION_HISTORY_SIZE];
|
|
volatile unsigned int _ptr;
|
|
};
|
|
|
|
} // namespace ZeroTier
|
|
|
|
#endif
|