ndhc/arp.h
Nicholas J. Kain 1732bccccc Relicense as MIT.
It's a lot more common than BSD 2-clause it is both compatible
and nearly identical in effect.
2022-02-06 20:05:29 -05:00

122 lines
4.3 KiB
C

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