ZeroTierOne/node/MulticastGroup.hpp
2019-08-26 20:18:28 -07:00

108 lines
3.4 KiB
C++

/*
* 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: 2023-01-01
*
* 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.
*/
/****/
#ifndef ZT_MULTICASTGROUP_HPP
#define ZT_MULTICASTGROUP_HPP
#include <stdint.h>
#include "Constants.hpp"
#include "MAC.hpp"
#include "InetAddress.hpp"
#include "Utils.hpp"
namespace ZeroTier {
/**
* A multicast group composed of a multicast MAC and a 32-bit ADI field
*
* ADI stands for additional distinguishing information. ADI is primarily for
* adding additional information to broadcast (ff:ff:ff:ff:ff:ff) memberships,
* since straight-up broadcast won't scale. Right now it's zero except for
* IPv4 ARP, where it holds the IPv4 address itself to make ARP into a
* selective multicast query that can scale.
*
* In the future we might add some kind of plugin architecture that can add
* ADI for things like mDNS (multicast DNS) to improve the selectivity of
* those protocols.
*
* MulticastGroup behaves as an immutable value object.
*/
class MulticastGroup
{
public:
ZT_ALWAYS_INLINE MulticastGroup() :
_mac(),
_adi(0)
{
}
ZT_ALWAYS_INLINE MulticastGroup(const MAC &m,uint32_t a) :
_mac(m),
_adi(a)
{
}
/**
* Derive the multicast group used for address resolution (ARP/NDP) for an IP
*
* @param ip IP address (port field is ignored)
* @return Multicast group for ARP/NDP
*/
static ZT_ALWAYS_INLINE MulticastGroup deriveMulticastGroupForAddressResolution(const InetAddress &ip)
{
if (ip.isV4()) {
// IPv4 wants broadcast MACs, so we shove the V4 address itself into
// the Multicast Group ADI field. Making V4 ARP work is basically why
// ADI was added, as well as handling other things that want mindless
// Ethernet broadcast to all.
return MulticastGroup(MAC(0xffffffffffffULL),Utils::ntoh(*((const uint32_t *)ip.rawIpData())));
} else if (ip.isV6()) {
// IPv6 is better designed in this respect. We can compute the IPv6
// multicast address directly from the IP address, and it gives us
// 24 bits of uniqueness. Collisions aren't likely to be common enough
// to care about.
const unsigned char *a = (const unsigned char *)ip.rawIpData();
return MulticastGroup(MAC(0x33,0x33,0xff,a[13],a[14],a[15]),0);
}
return MulticastGroup();
}
ZT_ALWAYS_INLINE const MAC &mac() const { return _mac; }
ZT_ALWAYS_INLINE uint32_t adi() const { return _adi; }
ZT_ALWAYS_INLINE unsigned long hashCode() const { return (_mac.hashCode() + (unsigned long)_adi); }
ZT_ALWAYS_INLINE bool operator==(const MulticastGroup &g) const { return ((_mac == g._mac)&&(_adi == g._adi)); }
ZT_ALWAYS_INLINE bool operator!=(const MulticastGroup &g) const { return ((_mac != g._mac)||(_adi != g._adi)); }
ZT_ALWAYS_INLINE bool operator<(const MulticastGroup &g) const
{
if (_mac < g._mac)
return true;
else if (_mac == g._mac)
return (_adi < g._adi);
return false;
}
ZT_ALWAYS_INLINE bool operator>(const MulticastGroup &g) const { return (g < *this); }
ZT_ALWAYS_INLINE bool operator<=(const MulticastGroup &g) const { return !(g < *this); }
ZT_ALWAYS_INLINE bool operator>=(const MulticastGroup &g) const { return !(*this < g); }
private:
MAC _mac;
uint32_t _adi;
};
} // namespace ZeroTier
#endif