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/*
* ZeroTier One - Global Peer to Peer Ethernet
* Copyright (C) 2012-2013 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_MULTICASTER_HPP
#define _ZT_MULTICASTER_HPP
#include <stdint.h>
#include <string.h>
#include <stdexcept>
#include <map>
#include <set>
#include <list>
#include <algorithm>
#include "Constants.hpp"
#include "Mutex.hpp"
#include "MulticastGroup.hpp"
#include "Address.hpp"
#include "Buffer.hpp"
namespace ZeroTier {
/**
* Multicast propagation algorithm core and database
*/
class Multicaster
{
public:
Multicaster();
~Multicaster();
/**
* Add or renew a peer's subscription to a multicast group
*
* @param nwid Network ID
* @param a Address that LIKEd
* @param mg Multicast group
* @param now Current time
*/
void likesGroup(uint64_t nwid,const Address &a,const MulticastGroup &mg,uint64_t now);
/**
* Bring a peer closer in terms of propagation priority
*
* This gets called from PacketDecoder when a unicast frame is received.
*
* @param nwid Network ID
* @param a Address to bring closer (e.g. due to unicast message)
* @param now Current time
*/
void bringCloser(uint64_t nwid,const Address &a);
/**
* Erase entries for expired LIKEs and GOT records
*/
void clean();
/**
* Multicast deduplicator
*
* This checks to see if a multicast GUID has been seen before. If not, it
* adds it to the history and returns false.
*
* @param nwid Network ID
* @param mcGuid Multicast GUID (sender address + sender unique ID)
* @return True if multicast IS a duplicate, false otherwise
*/
inline bool deduplicate(uint64_t nwid,uint64_t mcGuid)
throw()
{
Mutex::Lock _l(_lock);
_NetInfo &n = _nets[nwid];
for(unsigned int i=0;i<ZT_MULTICAST_DEDUP_HISTORY_LENGTH;++i) {
if (n.multicastHistory[i] == mcGuid)
return true;
}
n.multicastHistory[n.multicastHistoryPtr++ % ZT_MULTICAST_DEDUP_HISTORY_LENGTH] = mcGuid;
return false;
}
/**
* Pick next hops for a multicast by proximity
*
* The function or function object must return true if more hops are desired
* or false to stop finding new hops and return.
*
* @param nwid Network ID
* @param mg Multicast group
* @param nextHopFunc Function to call for each address, search stops if it returns false
*/
template<typename F>
inline void getNextHops(uint64_t nwid,const MulticastGroup &mg,F nextHopFunc)
{
Mutex::Lock _l(_lock);
std::map< uint64_t,_NetInfo >::iterator n(_nets.find(nwid));
if (n == _nets.end())
return;
std::map< MulticastGroup,std::list< Address > >::iterator p(n->second.proximity.find(mg));
if (p == n->second.proximity.end())
return;
for(std::list< Address >::iterator a(p->second.begin());a!=p->second.end();++a) {
if (!nextHopFunc(*a))
break;
}
}
/**
* Functor to add addresses to multicast frame propagation queues
*
* This function object checks the origin, bloom filter, and restriction
* prefix for each address and if all these pass it adds the address and
* increments the pointer pointed to by ptr. It stops (returns false) when
* *ptr reaches end. It's used in PacketDecoder and Switch with getNextHops()
* to compose multicast frame headers.
*/
class AddToPropagationQueue
{
public:
/**
* @param ptr Pointer to pointer to current position in queue
* @param end End of queue
* @param bloom Bloom filter field (must be 1024 bytes in length)
* @param bloomNonce Random nonce for bloom filter randomization
* @param origin Originating address
* @param prefixBits Number of bits in propagation restriction prefix
* @param prefix Propagation restrition prefix
*/
AddToPropagationQueue(unsigned char **ptr,unsigned char *end,unsigned char *bloom,uint16_t bloomNonce,const Address &origin,unsigned int prefixBits,unsigned int prefix)
throw() :
_origin(origin),
_bloomNonce((uint64_t)bloomNonce),
_prefixMask(0xffffffffffffffffULL >> (64 - prefixBits)),
_prefix((uint64_t)prefix & _prefixMask),
_ptr(ptr),
_end(end),
_bloom(bloom) {}
inline bool operator()(const Address &a)
throw()
{
// Exclude original sender -- obviously they've already seen it
if (a == _origin)
return true;
// Exclude addresses not in this prefix domain
if ((a.toInt() & _prefixMask) != _prefix)
return true;
// Exclude addresses remembered in bloom filter -- or else remember them
uint64_t aint = a.toInt() + _bloomNonce;
const unsigned int bit = (unsigned int)(aint ^ (aint >> 13) ^ (aint >> 26) ^ (aint >> 39)) & 0x1fff;
unsigned char *const bbyte = _bloom + (bit >> 3); // note: bloom filter size == 1024 is hard-coded here
const unsigned char bmask = 1 << (bit & 7);
if ((*bbyte & bmask))
return true;
else *bbyte |= bmask;
a.copyTo(*_ptr,ZT_ADDRESS_LENGTH);
return ((*_ptr += ZT_ADDRESS_LENGTH) != _end);
}
private:
const Address _origin;
const uint64_t _bloomNonce;
const uint64_t _prefixMask;
const uint64_t _prefix;
unsigned char **const _ptr;
unsigned char *const _end;
unsigned char *const _bloom;
};
private:
// Information about a subscription
struct _SubInfo
{
_SubInfo() :
lastLike(0),
proximitySlot() {}
// Time of last MULTICAST_LIKE for this group
uint64_t lastLike;
// Slot in corresponding list in _proximity
std::list< Address >::iterator proximitySlot;
};
// An address and multicast group tuple
typedef std::pair< Address,MulticastGroup > _Subscription;
// Multicast info for a given network
struct _NetInfo
{
_NetInfo()
throw()
{
memset(multicastHistory,0,sizeof(multicastHistory));
multicastHistoryPtr = 0;
}
// Ring buffer of most recently injected multicast packet GUIDs
uint64_t multicastHistory[ZT_MULTICAST_DEDUP_HISTORY_LENGTH];
unsigned int multicastHistoryPtr;
// Peer proximity ordering for peers subscribed to each group
std::map< MulticastGroup,std::list< Address > > proximity;
// Peer subscriptions to multicast groups
std::map< _Subscription,_SubInfo > subscriptions;
};
std::map< uint64_t,_NetInfo > _nets;
Mutex _lock;
};
} // namespace ZeroTier
#endif
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