eth_arp.h

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// Copyright 2021-2025 The Aerospace Corporation.
// This file is a part of SatCat5, licensed under CERN-OHL-W v2 or later.
 
#pragma once
 
#include <satcat5/ethernet.h>
#include <satcat5/ip_core.h>
#include <satcat5/list.h>
 
namespace satcat5 {
    namespace eth {
        struct ArpHeader {
            u16 oper;                           // Operation (1 = request, 2 = reply)
            satcat5::eth::MacAddr   sha, tha;   // MAC ("hardware address")
            satcat5::ip::Addr       spa, tpa;   // IPv4 ("protocol address")
 
            constexpr ArpHeader()
                : oper(0), sha{}, tha{}, spa(), tpa() {}
            ArpHeader(const ArpHeader& t) = default;
            ArpHeader& operator=(const ArpHeader& t) = default;
 
            bool read_from(satcat5::io::Readable* rd);
 
            void write_to(satcat5::io::Writeable* wr) const;
        };
 
        class ArpListener {
        public:
            virtual void arp_event(
                const satcat5::eth::MacAddr& mac,
                const satcat5::ip::Addr& ip) = 0;
 
            virtual void gateway_change(
                const satcat5::ip::Addr& dstaddr,
                const satcat5::ip::Addr& gateway) {}
 
        private:
            // Linked list to the next listener object.
            friend satcat5::util::ListCore;
            satcat5::eth::ArpListener* m_next;
        };
 
        class ProtoArp : public satcat5::eth::Protocol {
        public:
            ProtoArp(
                satcat5::eth::Dispatch* dispatcher,
                const satcat5::ip::Addr& ipaddr = satcat5::ip::ADDR_NONE);
 
            inline void add(satcat5::eth::ArpListener* evt)
                {m_listeners.add(evt);}
            inline void remove(satcat5::eth::ArpListener* evt)
                {m_listeners.remove(evt);}
 
            inline void set_ipaddr(const satcat5::ip::Addr& ipaddr)
                {m_ipaddr = ipaddr;}
 
            inline void set_proxy(const satcat5::ip::Table* table)
                {m_table = table;}
 
            bool send_announce(
                const satcat5::eth::VlanTag& vtag = satcat5::eth::VTAG_NONE) const;
 
            bool send_probe(
                const satcat5::ip::Addr& target,
                const satcat5::eth::VlanTag& vtag = satcat5::eth::VTAG_NONE);
 
            bool send_query(
                const satcat5::ip::Addr& target,
                const satcat5::eth::VlanTag& vtag = satcat5::eth::VTAG_NONE);
 
            void gateway_change(
                const satcat5::ip::Addr& dstaddr,
                const satcat5::ip::Addr& gateway);
 
            void frame_rcvd(satcat5::io::LimitedRead& src) override;
 
        protected:
            satcat5::eth::MacAddr match(const satcat5::eth::ArpHeader& hdr) const;
 
            bool send_internal(u16 opcode,
                const satcat5::eth::VlanTag& vtag,
                const satcat5::eth::MacAddr& dst,
                const satcat5::eth::MacAddr& sha,
                const satcat5::ip::Addr& spa,
                const satcat5::eth::MacAddr& tha,
                const satcat5::ip::Addr& tpa) const;
 
            satcat5::ip::Addr m_ipaddr;
            const satcat5::ip::Table* m_table;
            satcat5::util::List<satcat5::eth::ArpListener> m_listeners;
        };
    }
}