/*
 * 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/
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "Constants.hpp"
#include "SelfAwareness.hpp"
#include "RuntimeEnvironment.hpp"
#include "Node.hpp"
#include "Topology.hpp"
#include "Packet.hpp"
#include "Peer.hpp"

namespace ZeroTier {

class _ResetWithinScope
{
public:
	_ResetWithinScope(const RuntimeEnvironment *renv,uint64_t now,InetAddress::IpScope scope) :
		RR(renv),
		_now(now),
		_scope(scope) {}

	inline void operator()(Topology &t,const SharedPtr<Peer> &p)
	{
		if (p->resetWithinScope(RR,_scope,_now))
			peersReset.push_back(p);
	}

	std::vector< SharedPtr<Peer> > peersReset;

private:
	const RuntimeEnvironment *RR;
	uint64_t _now;
	InetAddress::IpScope _scope;
};

SelfAwareness::SelfAwareness(const RuntimeEnvironment *renv) :
	RR(renv)
{
	memset(_lastPhysicalAddress,0,sizeof(_lastPhysicalAddress));
}

SelfAwareness::~SelfAwareness()
{
}

void SelfAwareness::iam(const Address &reporter,const InetAddress &reporterPhysicalAddress,const InetAddress &myPhysicalAddress,bool trusted)
{
	// This code depends on the numeric values assigned to scopes in InetAddress.hpp
	const unsigned int scope = (unsigned int)myPhysicalAddress.ipScope();
	if ((scope > 0)&&(scope < (unsigned int)InetAddress::IP_SCOPE_LOOPBACK)) {
		if ( (!trusted) && ((scope == (unsigned int)InetAddress::IP_SCOPE_GLOBAL)||(scope != (unsigned int)reporterPhysicalAddress.ipScope())) ) {
			/* For now only trusted peers are permitted to inform us of changes to
			 * our global Internet IP or to changes of NATed IPs. We'll let peers on
			 * private, shared, or link-local networks inform us of changes as long
			 * as they too are at the same scope. This discrimination avoids a DoS
			 * attack in which an attacker could force us to reset our connections. */
			return;
		} else {
			Mutex::Lock _l(_lock);
			InetAddress &lastPhy = _lastPhysicalAddress[scope - 1];
			if (!lastPhy) {
				TRACE("learned physical address %s for scope %u from reporter %s(%s) (replaced <null>)",myPhysicalAddress.toString().c_str(),scope,reporter.toString().c_str(),reporterPhysicalAddress.toString().c_str());
				lastPhy = myPhysicalAddress;
			} else if (lastPhy != myPhysicalAddress) {
				TRACE("learned physical address %s for scope %u from reporter %s(%s) (replaced %s, resetting within scope)",myPhysicalAddress.toString().c_str(),scope,reporter.toString().c_str(),reporterPhysicalAddress.toString().c_str(),lastPhy.toString().c_str());
				lastPhy = myPhysicalAddress;
				uint64_t now = RR->node->now();

				_ResetWithinScope rset(RR,now,(InetAddress::IpScope)scope);
				RR->topology->eachPeer<_ResetWithinScope &>(rset);

				// For all peers for whom we forgot an address, send a packet indirectly if
				// they are still considered alive so that we will re-establish direct links.
				SharedPtr<Peer> sn(RR->topology->getBestSupernode());
				if (sn) {
					Path *snp = sn->getBestPath(now);
					if (snp) {
						for(std::vector< SharedPtr<Peer> >::const_iterator p(rset.peersReset.begin());p!=rset.peersReset.end();++p) {
							if ((*p)->alive(now)) {
								TRACE("sending indirect NOP to %s via %s(%s) to re-establish link",(*p)->address().toString().c_str(),sn->address().toString().c_str(),snp->address().toString().c_str());
								Packet outp((*p)->address(),RR->identity.address(),Packet::VERB_NOP);
								outp.armor((*p)->key(),true);
								snp->send(RR,outp.data(),outp.size(),now);
							}
						}
					}
				}
			}
		}
	}
}

} // namespace ZeroTier