122 lines
4.3 KiB
C
122 lines
4.3 KiB
C
// Copyright 2010-2018 Nicholas J. Kain <njkain at gmail dot com>
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// SPDX-License-Identifier: MIT
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#ifndef ARP_H_
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#define ARP_H_
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#include <stdbool.h>
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#include <stdint.h>
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#include <net/if_arp.h>
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#include "ndhc.h"
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#include "dhcp.h"
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struct arpMsg {
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// Ethernet header
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uint8_t h_dest[6]; // 00 destination ether addr
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uint8_t h_source[6]; // 06 source ether addr
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uint16_t h_proto; // 0c packet type ID field
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// ARP packet
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uint16_t htype; // 0e hardware type (must be ARPHRD_ETHER)
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uint16_t ptype; // 10 protocol type (must be ETH_P_IP)
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uint8_t hlen; // 12 hardware address length (must be 6)
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uint8_t plen; // 13 protocol address length (must be 4)
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uint16_t operation; // 14 ARP opcode
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uint8_t smac[6]; // 16 sender's hardware address
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uint8_t sip4[4]; // 1c sender's IP address
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uint8_t dmac[6]; // 20 target's hardware address
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uint8_t dip4[4]; // 26 target's IP address
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uint8_t pad[18]; // 2a pad for min. ethernet payload (60 bytes)
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};
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extern unsigned arp_probe_wait;
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extern unsigned arp_probe_num;
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extern unsigned arp_probe_min;
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extern unsigned arp_probe_max;
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typedef enum {
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AS_NONE = 0, // Nothing to react to wrt ARP
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AS_ANNOUNCE, // Announcing our MAC/IP mapping to ethernet peers.
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AS_COLLISION_CHECK, // Checking to see if another host has our IP before
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// accepting a new lease.
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AS_QUERY_GW_SEND, // Sending arp_ping to query the gateway MAC.
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AS_GW_CHECK, // Seeing if the default GW still exists on the local
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// segment after the hardware link was lost.
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AS_GW_QUERY, // Finding the default GW MAC address.
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AS_DEFENSE, // Defending our IP address (RFC5227)
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AS_MAX,
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} arp_state_t;
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typedef enum {
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ASEND_COLLISION_CHECK,
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ASEND_GW_PING,
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ASEND_ANNOUNCE,
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ASEND_MAX,
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} arp_send_t;
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struct arp_stats {
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long long ts;
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unsigned count;
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};
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struct arp_data {
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struct dhcpmsg dhcp_packet; // Used only for AS_COLLISION_CHECK
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struct arpMsg reply;
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struct arp_stats send_stats[ASEND_MAX];
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long long wake_ts[AS_MAX];
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long long last_conflict_ts; // TS of the last conflicting ARP seen.
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long long arp_check_start_ts; // TS of when we started the
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// AS_COLLISION_CHECK state.
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unsigned int total_conflicts; // Total number of address conflicts on
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// the interface. Never decreases.
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unsigned gw_check_initpings; // Initial count of ASEND_GW_PING when
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// AS_GW_CHECK was entered.
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uint16_t probe_wait_time; // Time to wait for a COLLISION_CHECK reply
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// (in ms?).
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bool using_bpf:1; // Is a BPF installed on the ARP socket?
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bool relentless_def:1; // Don't give up defense no matter what.
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bool router_replied:1;
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bool server_replied:1;
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};
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void arp_reset_state(struct client_state_t *cs);
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bool arp_packet_get(struct client_state_t *cs);
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void set_arp_relentless_def(bool v);
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int arp_check(struct client_state_t *cs,
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struct dhcpmsg *packet);
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int arp_gw_check(struct client_state_t *cs);
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int arp_set_defense_mode(struct client_state_t *cs);
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int arp_gw_failed(struct client_state_t *cs);
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int arp_do_collision_check(struct client_state_t *cs);
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int arp_collision_timeout(struct client_state_t *cs, long long nowts);
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int arp_query_gateway(struct client_state_t *cs);
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int arp_query_gateway_timeout(struct client_state_t *cs, long long nowts);
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int arp_announce(struct client_state_t *cs);
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int arp_announce_timeout(struct client_state_t *cs, long long nowts);
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int arp_do_defense(struct client_state_t *cs);
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int arp_defense_timeout(struct client_state_t *cs, long long nowts);
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int arp_do_gw_query(struct client_state_t *cs);
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int arp_gw_query_timeout(struct client_state_t *cs, long long nowts);
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int arp_do_gw_check(struct client_state_t *cs);
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int arp_gw_check_timeout(struct client_state_t *cs, long long nowts);
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// No action needs to be taken.
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#define ARPR_OK 0
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// There was no conflict with another host.
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#define ARPR_FREE 1
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// Another host already has our assigned address.
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#define ARPR_CONFLICT -1
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// The operation couldn't complete because of an error such as rfkill.
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#define ARPR_FAIL -2
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long long arp_get_wake_ts(void);
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#endif
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