mirror of
https://github.com/zerotier/ZeroTierOne.git
synced 2025-01-13 08:20:03 +00:00
135 lines
3.7 KiB
C++
135 lines
3.7 KiB
C++
/*
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* Copyright (c)2019 ZeroTier, Inc.
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*
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* Use of this software is governed by the Business Source License included
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* in the LICENSE.TXT file in the project's root directory.
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*
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* Change Date: 2026-01-01
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*
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* On the date above, in accordance with the Business Source License, use
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* of this software will be governed by version 2.0 of the Apache License.
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*/
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/****/
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#ifndef ZT_MULTICASTGROUP_HPP
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#define ZT_MULTICASTGROUP_HPP
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#include "InetAddress.hpp"
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#include "MAC.hpp"
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#include <stdint.h>
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namespace ZeroTier {
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/**
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* A multicast group composed of a multicast MAC and a 32-bit ADI field
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*
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* ADI stands for additional distinguishing information. ADI is primarily for
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* adding additional information to broadcast (ff:ff:ff:ff:ff:ff) memberships,
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* since straight-up broadcast won't scale. Right now it's zero except for
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* IPv4 ARP, where it holds the IPv4 address itself to make ARP into a
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* selective multicast query that can scale.
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*
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* In the future we might add some kind of plugin architecture that can add
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* ADI for things like mDNS (multicast DNS) to improve the selectivity of
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* those protocols.
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*
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* MulticastGroup behaves as an immutable value object.
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*/
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class MulticastGroup {
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public:
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MulticastGroup() : _mac(), _adi(0)
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{
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}
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MulticastGroup(const MAC& m, uint32_t a) : _mac(m), _adi(a)
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{
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}
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/**
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* Derive the multicast group used for address resolution (ARP/NDP) for an IP
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*
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* @param ip IP address (port field is ignored)
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* @return Multicast group for ARP/NDP
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*/
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static inline MulticastGroup deriveMulticastGroupForAddressResolution(const InetAddress& ip)
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{
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if (ip.isV4()) {
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// IPv4 wants broadcast MACs, so we shove the V4 address itself into
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// the Multicast Group ADI field. Making V4 ARP work is basically why
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// ADI was added, as well as handling other things that want mindless
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// Ethernet broadcast to all.
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return MulticastGroup(MAC(0xffffffffffffULL), Utils::ntoh(*((const uint32_t*)ip.rawIpData())));
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}
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else if (ip.isV6()) {
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// IPv6 is better designed in this respect. We can compute the IPv6
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// multicast address directly from the IP address, and it gives us
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// 24 bits of uniqueness. Collisions aren't likely to be common enough
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// to care about.
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const unsigned char* a = (const unsigned char*)ip.rawIpData();
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return MulticastGroup(MAC(0x33, 0x33, 0xff, a[13], a[14], a[15]), 0);
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}
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return MulticastGroup();
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}
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/**
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* @return Multicast address
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*/
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inline const MAC& mac() const
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{
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return _mac;
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}
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/**
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* @return Additional distinguishing information
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*/
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inline uint32_t adi() const
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{
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return _adi;
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}
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inline unsigned long hashCode() const
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{
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return (_mac.hashCode() ^ (unsigned long)_adi);
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}
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inline bool operator==(const MulticastGroup& g) const
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{
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return ((_mac == g._mac) && (_adi == g._adi));
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}
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inline bool operator!=(const MulticastGroup& g) const
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{
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return ((_mac != g._mac) || (_adi != g._adi));
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}
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inline bool operator<(const MulticastGroup& g) const
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{
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if (_mac < g._mac) {
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return true;
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}
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else if (_mac == g._mac) {
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return (_adi < g._adi);
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}
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return false;
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}
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inline bool operator>(const MulticastGroup& g) const
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{
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return (g < *this);
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}
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inline bool operator<=(const MulticastGroup& g) const
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{
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return ! (g < *this);
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}
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inline bool operator>=(const MulticastGroup& g) const
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{
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return ! (*this < g);
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}
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private:
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MAC _mac;
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uint32_t _adi;
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};
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} // namespace ZeroTier
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#endif
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