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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 <list>
#include <algorithm>
#include "Constants.hpp"
#include "Mutex.hpp"
#include "MulticastGroup.hpp"
#include "Utils.hpp"
#include "Address.hpp"
namespace ZeroTier {
/**
* Multicast propagation algorithm
*/
class Multicaster
{
public:
Multicaster() {}
/**
* Add or renew a peer's subscription to a multicast group
*
* @param a Address that LIKEd
* @param mg Multicast group
* @param now Current time
*/
inline void likesGroup(const Address &a,const MulticastGroup &mg,uint64_t now)
{
Mutex::Lock _l(_lock);
_SubInfo &si = _subscriptions[_Subscription(a,mg)];
if (!si.lastLike) { // on first LIKE, we must add to _proximity[mg]
std::list< Address > &p = _proximity[mg];
p.push_front(a);
si.proximitySlot = p.begin(); // list's iterators remain valid until erase()
}
si.lastLike = now;
}
/**
* Bring a peer closer in terms of propagation priority
*
* @param a Address to bring closer (e.g. due to unicast message)
* @param now Current time
*/
inline void bringCloser(const Address &a)
{
Mutex::Lock _l(_lock);
// _subscriptions contains pairs of <Address,MulticastGroup>, so we can
// easily iterate through all subscriptions for a given address by
// starting with the default all-zero MulticastGroup() as lower bound
// and stopping when we're not looking at the right address anymore.
// Then we can look up _proximity and rapidly splice() the list using
// the saved iterator in _SubInfo.
std::map< _Subscription,_SubInfo >::iterator s(_subscriptions.lower_bound(_Subscription(a,MulticastGroup())));
while ((s != _subscriptions.end())&&(s->first.first == a)) {
std::map< MulticastGroup,std::list< Address > >::iterator p(_proximity.find(s->first.second));
if (s->second.proximitySlot != p->second.begin())
p->second.splice(p->second.begin(),p->second,s->second.proximitySlot);
++s;
}
}
/**
* Indicate that a peer reported that it GOT a multicast
*
* This only happens on magnet nodes for a propagation.
*
* @param mcGuid Multicast GUID
* @param peer Peer that GOT multicast
* @param now Current time
*/
inlien void got(const Address &peer,uint64_t mcGuid,uint64_t now)
{
Mutex::Lock _l(_lock);
std::pair< uint64_t,std::set<Address> > &g = _got[mcGuid];
g.first = now;
g.second.insert(peer);
}
/**
* Erase entries for expired LIKEs and GOT records
*/
inline void clean(uint64_t now)
{
Mutex::Lock _l(_lock);
for(std::map< uint64_t,std::pair< uint64_t,std::set<Address> > >::iterator g(_got.begin());g!=_got.end();) {
if ((now - g->second.first) > ZT_MULTICAST_MAGNET_STATE_EXPIRE)
_got.erase(g++);
else ++g;
}
for(std::map< _Subscription,_SubInfo >::iterator s(_subscriptions.begin());s!=_subscriptions.end();) {
if ((now - s->second.lastLike) > ZT_MULTICAST_LIKE_EXPIRE) {
std::map< MulticastGroup,std::list< Address > > p(_proximity.find(s->first.second));
p->second.erase(s->second.proximitySlot);
if (p->second.empty())
_proximity.erase(p);
_subscriptions.erase(s++);
} else ++s;
}
}
/**
* 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 mg Multicast group
* @param mcGuid Multicast message GUID (signer and signer unique ID)
* @param nextHopFunc Function to call for each address, search stops if it returns false
*/
template<typename F>
inline void getNextHops(const MulticastGroup &mg,uint64_t mcGuid,F nextHopFunc)
{
Mutex::Lock _l(_lock);
std::map< uint64_t,std::pair< uint64_t,std::set< Address > > > g(_got.find(mcGuid));
std::map< MulticastGroup,std::list< Address > > p(_proximity.find(mg));
if (p != _proximity.end()) {
for(std::list< Address >::iterator a(p->second.begin());a!=p->second.end();++a) {
if ((g == _got.end())||(!g->second.second.count(*a))) {
if (!nextHopFunc(*a))
break;
}
}
}
}
private:
// GOTs by multicast GUID: time of last GOT, addresses that GOT
std::map< uint64_t,std::pair< uint64_t,std::set< Address > > > _got;
// Peer proximity ordering for peers subscribed to each group
std::map< MulticastGroup,std::list< Address > > _proximity;
// An address and multicast group tuple
typedef std::pair<Address,MulticastGroup> _Subscription;
// 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;
};
// Peer subscriptions to multicast groups
std::map< _Subscription,_SubInfo > _subscriptions;
Mutex _lock;
};
} // namespace ZeroTier
#endif
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