/*
 * Copyright (c)2013-2020 ZeroTier, Inc.
 *
 * Use of this software is governed by the Business Source License included
 * in the LICENSE.TXT file in the project's root directory.
 *
 * Change Date: 2024-01-01
 *
 * On the date above, in accordance with the Business Source License, use
 * of this software will be governed by version 2.0 of the Apache License.
 */
/****/

#include "Constants.hpp"
#include "SelfAwareness.hpp"
#include "RuntimeEnvironment.hpp"
#include "Topology.hpp"
#include "Peer.hpp"
#include "Trace.hpp"
#include "Containers.hpp"

// Entry timeout -- make it fairly long since this is just to prevent stale buildup
#define ZT_SELFAWARENESS_ENTRY_TIMEOUT 300000

namespace ZeroTier {

class _ResetWithinScope
{
public:
	ZT_INLINE _ResetWithinScope(void *tPtr, int64_t now, int inetAddressFamily, InetAddress::IpScope scope) :
		_now(now),
		_tPtr(tPtr),
		_family(inetAddressFamily),
		_scope(scope)
	{}

	ZT_INLINE void operator()(const SharedPtr<Peer> &p)
	{ p->resetWithinScope(_tPtr, _scope, _family, _now); }

private:
	int64_t _now;
	void *_tPtr;
	int _family;
	InetAddress::IpScope _scope;
};

SelfAwareness::SelfAwareness(const RuntimeEnvironment *renv) :
	RR(renv)
{
}

void SelfAwareness::iam(void *tPtr, const Identity &reporter, const int64_t receivedOnLocalSocket, const InetAddress &reporterPhysicalAddress, const InetAddress &myPhysicalAddress, bool trusted, int64_t now)
{
	const InetAddress::IpScope scope = myPhysicalAddress.ipScope();

	if ((scope != reporterPhysicalAddress.ipScope()) || (scope == InetAddress::IP_SCOPE_NONE) || (scope == InetAddress::IP_SCOPE_LOOPBACK) || (scope == InetAddress::IP_SCOPE_MULTICAST))
		return;

	Mutex::Lock l(m_phy_l);
	p_PhySurfaceEntry &entry = m_phy[p_PhySurfaceKey(reporter.address(), receivedOnLocalSocket, reporterPhysicalAddress, scope)];

	if ((trusted) && ((now - entry.ts) < ZT_SELFAWARENESS_ENTRY_TIMEOUT) && (!entry.mySurface.ipsEqual(myPhysicalAddress))) {
		// Changes to external surface reported by trusted peers causes path reset in this scope
		entry.mySurface = myPhysicalAddress;
		entry.ts = now;
		entry.trusted = trusted;

		// Erase all entries in this scope that were not reported from this remote address to prevent 'thrashing'
		// due to multiple reports of endpoint change.
		// Don't use 'entry' after this since hash table gets modified.
		for (Map<p_PhySurfaceKey, p_PhySurfaceEntry>::iterator i(m_phy.begin());i != m_phy.end();) {
			if ((i->first.scope == scope) && (i->first.reporterPhysicalAddress != reporterPhysicalAddress))
				m_phy.erase(i++);
			else ++i;
		}

		// Reset all paths within this scope and address family
		_ResetWithinScope rset(tPtr, now, myPhysicalAddress.family(), (InetAddress::IpScope) scope);
		RR->topology->eachPeer<_ResetWithinScope &>(rset);

		RR->t->resettingPathsInScope(tPtr, 0x9afff100, reporter, reporterPhysicalAddress, entry.mySurface, myPhysicalAddress, scope);
	} else {
		// Otherwise just update DB to use to determine external surface info
		entry.mySurface = myPhysicalAddress;
		entry.ts = now;
		entry.trusted = trusted;
	}
}

void SelfAwareness::clean(int64_t now)
{
	Mutex::Lock l(m_phy_l);
	for (Map<p_PhySurfaceKey, p_PhySurfaceEntry>::iterator i(m_phy.begin());i != m_phy.end();) {
		if ((now - i->second.ts) >= ZT_SELFAWARENESS_ENTRY_TIMEOUT)
			m_phy.erase(i++);
		else ++i;
	}
}

MultiMap<unsigned int, InetAddress> SelfAwareness::externalAddresses(const int64_t now) const
{
	MultiMap<unsigned int, InetAddress> r;

	// Count endpoints reporting each IP/port combo
	Map<InetAddress, unsigned long> counts;
	{
		Mutex::Lock l(m_phy_l);
		for (Map<p_PhySurfaceKey, p_PhySurfaceEntry>::const_iterator i(m_phy.begin());i != m_phy.end();++i) {
			if ((now - i->second.ts) < ZT_SELFAWARENESS_ENTRY_TIMEOUT)
				++counts[i->second.mySurface];
		}
	}

	// Invert to create a map from count to address
	for (Map<InetAddress, unsigned long>::iterator i(counts.begin());i != counts.end();++i)
		r.insert(std::pair<unsigned long, InetAddress>(i->second, i->first));

	return r;
}

} // namespace ZeroTier