ip_dispatch.h

// Copyright 2021-2025 The Aerospace Corporation.
// This file is a part of SatCat5, licensed under CERN-OHL-W v2 or later.
// Protocol handler and dispatch unit for Internet Protocol v4 (IPv4)
 
#pragma once
 
#include <satcat5/eth_arp.h>
#include <satcat5/eth_dispatch.h>
#include <satcat5/igmp_client.h>
#include <satcat5/ip_core.h>
#include <satcat5/ip_icmp.h>
#include <satcat5/ip_table.h>
#include <satcat5/net_core.h>
#include <satcat5/utils.h>
 
// Time To Live (TTL) sets maximum number of router hops.
// This parameter sets the default for outgoing packets.
#ifndef SATCAT5_IP_TTL
#define SATCAT5_IP_TTL 128
#endif
 
namespace satcat5 {
    namespace ip {
        class Dispatch final
            : public satcat5::eth::ArpListener
            , public satcat5::net::Protocol
            , public satcat5::net::Dispatch
        {
        public:
            Dispatch(
                const satcat5::ip::Addr& addr,
                satcat5::eth::Dispatch* iface,
                satcat5::ip::Table* route);
            ~Dispatch() SATCAT5_OPTIONAL_DTOR;
 
            satcat5::io::Writeable* open_reply(
                const satcat5::net::Type& type, unsigned len) override;
 
            satcat5::io::Writeable* open_write(
                const satcat5::eth::MacAddr& mac,   // Destination MAC
                const satcat5::eth::VlanTag& vtag,  // VLAN information
                const satcat5::ip::Addr& ip,        // Destination IP
                u8 protocol,                        // Protocol (UDP/TCP/etc)
                unsigned len);                      // Length after IP header
 
            void set_addr(const satcat5::ip::Addr& addr);
 
            satcat5::ip::Header next_header(
                u8 protocol,
                const satcat5::ip::Addr& dst,
                unsigned inner_bytes,
                u8 ttl = SATCAT5_IP_TTL);
 
            inline void route_clear(bool lockdown = true)
                { m_route->route_clear(lockdown); }
            inline bool route_cache(
                const satcat5::ip::Addr& gateway,
                const satcat5::eth::MacAddr& dstmac)
                { return m_route->route_cache(gateway, dstmac); }
            inline bool route_default(
                const satcat5::ip::Addr& gateway,
                const satcat5::eth::MacAddr& dstmac = satcat5::eth::MACADDR_NONE)
                { return m_route->route_default(gateway, dstmac); }
            inline bool route_local(const satcat5::ip::Subnet& subnet)
                { return m_route->route_local(subnet); }
            inline bool route_simple(
                const satcat5::ip::Addr& gateway,
                const satcat5::ip::Mask& subnet = satcat5::ip::MASK_24)
                { return m_route->route_simple(gateway, subnet); }
            inline bool route_static(
                const satcat5::ip::Subnet& subnet,
                const satcat5::ip::Addr& gateway,
                const satcat5::eth::MacAddr& dstmac = satcat5::eth::MACADDR_NONE)
                { return m_route->route_static(subnet, gateway, dstmac); }
            inline bool route_remove(const satcat5::ip::Subnet& subnet)
                { return m_route->route_remove(subnet); }
            inline bool route_remove(const satcat5::ip::Addr& addr)
                { return m_route->route_remove(addr); }
            inline satcat5::ip::Route route_lookup(
                const satcat5::ip::Addr& dstaddr) const
                { return m_route->route_lookup(dstaddr); }
 
            // Other accessors:
            inline satcat5::eth::ProtoArp* arp()
                { return &m_arp; }
            inline satcat5::ip::ProtoIcmp* icmp()
                { return &m_icmp; }
            inline satcat5::igmp::Client* igmp()
                { return &m_igmp; }
            inline satcat5::eth::Dispatch* iface() const
                { return m_iface; }
            inline satcat5::ip::Addr ipaddr() const
                { return m_addr; }
            inline satcat5::eth::MacAddr macaddr() const
                { return m_iface->macaddr(); }
            inline satcat5::eth::VlanTag reply_vtag() const
                { return m_iface->reply_vtag(); }
            inline satcat5::eth::MacAddr reply_mac() const
                { return m_iface->reply_mac(); }
            inline bool reply_is_multicast() const
                { return m_reply_dst.is_multicast(); }
            inline satcat5::ip::Addr reply_ip() const
                { return m_reply_src; }
            inline const satcat5::ip::Header& reply_hdr() const
                { return m_reply_hdr; }
            inline void set_ipaddr(const satcat5::ip::Addr& addr)
                { set_addr(addr); }
            inline void set_macaddr(const satcat5::eth::MacAddr& macaddr)
                { m_iface->set_macaddr(macaddr); }
            inline satcat5::ip::Table* table()
                { return m_route; }
 
            inline void set_ident(u16 ident)
                { m_ident = ident; }
 
        protected:
            // Event handler for the ARP cache.
            void arp_event(
                const satcat5::eth::MacAddr& mac,
                const satcat5::ip::Addr& ip) override;
 
            // Event handler for incoming IPv4 frames.
            void frame_rcvd(satcat5::io::LimitedRead& src) override;
 
            // Pointer to the parent interface.
            satcat5::eth::Dispatch* const m_iface;
            satcat5::ip::Table* const m_route;
 
            // IP address for this interface.
            satcat5::ip::Addr m_addr;
 
            // ARP, ICMP, and IGMP handlers for this interface.
            satcat5::eth::ProtoArp m_arp;
            satcat5::ip::ProtoIcmp m_icmp;
            satcat5::igmp::Client m_igmp;
 
            // The current reply state (address + complete header).
            satcat5::ip::Addr m_reply_dst;
            satcat5::ip::Addr m_reply_src;
            satcat5::ip::Header m_reply_hdr;
 
            // Identification field for outgoing packets.
            u16 m_ident;
        };
    }
}