/*
 * Copyright (c)2019 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: 2026-01-01
 *
 * 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 "SelfAwareness.hpp"

#include "Constants.hpp"
#include "Node.hpp"
#include "Packet.hpp"
#include "Peer.hpp"
#include "RuntimeEnvironment.hpp"
#include "Switch.hpp"
#include "Topology.hpp"
#include "Trace.hpp"

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

// Entry timeout -- make it fairly long since this is just to prevent stale buildup
#define ZT_SELFAWARENESS_ENTRY_TIMEOUT 600000

namespace ZeroTier {

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

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

  private:
    uint64_t _now;
    void* _tPtr;
    int _family;
    InetAddress::IpScope _scope;
};

SelfAwareness::SelfAwareness(const RuntimeEnvironment* renv) : RR(renv), _phy(128)
{
}

void SelfAwareness::iam(void* tPtr, const Address& 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(_phy_m);
    PhySurfaceEntry& entry = _phy[PhySurfaceKey(reporter, 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
        RR->t->resettingPathsInScope(tPtr, reporter, reporterPhysicalAddress, myPhysicalAddress, 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.
        {
            Hashtable<PhySurfaceKey, PhySurfaceEntry>::Iterator i(_phy);
            PhySurfaceKey* k = (PhySurfaceKey*)0;
            PhySurfaceEntry* e = (PhySurfaceEntry*)0;
            while (i.next(k, e)) {
                if ((k->reporterPhysicalAddress != reporterPhysicalAddress) && (k->scope == scope)) {
                    _phy.erase(*k);
                }
            }
        }

        // Reset all paths within this scope and address family
        _ResetWithinScope rset(tPtr, now, myPhysicalAddress.ss_family, (InetAddress::IpScope)scope);
        RR->topology->eachPeer<_ResetWithinScope&>(rset);
    }
    else {
        // Otherwise just update DB to use to determine external surface info
        entry.mySurface = myPhysicalAddress;
        entry.ts = now;
        entry.trusted = trusted;
    }
}

std::vector<InetAddress> SelfAwareness::whoami()
{
    std::vector<InetAddress> surfaceAddresses;
    Mutex::Lock _l(_phy_m);
    Hashtable<PhySurfaceKey, PhySurfaceEntry>::Iterator i(_phy);
    PhySurfaceKey* k = (PhySurfaceKey*)0;
    PhySurfaceEntry* e = (PhySurfaceEntry*)0;
    while (i.next(k, e)) {
        if (std::find(surfaceAddresses.begin(), surfaceAddresses.end(), e->mySurface) == surfaceAddresses.end()) {
            surfaceAddresses.push_back(e->mySurface);
        }
    }
    return surfaceAddresses;
}

void SelfAwareness::clean(int64_t now)
{
    Mutex::Lock _l(_phy_m);
    Hashtable<PhySurfaceKey, PhySurfaceEntry>::Iterator i(_phy);
    PhySurfaceKey* k = (PhySurfaceKey*)0;
    PhySurfaceEntry* e = (PhySurfaceEntry*)0;
    while (i.next(k, e)) {
        if ((now - e->ts) >= ZT_SELFAWARENESS_ENTRY_TIMEOUT) {
            _phy.erase(*k);
        }
    }
}

}   // namespace ZeroTier