1/* Definitions for Address Resolution Protocol.
2 Copyright (C) 1997-2026 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19/* Based on the 4.4BSD and Linux version of this file. */
20
21#ifndef _NET_IF_ARP_H
22#define _NET_IF_ARP_H 1
23
24#include <sys/types.h>
25#include <sys/socket.h>
26#include <stdint.h>
27
28__BEGIN_DECLS
29
30/* Some internals from deep down in the kernel. */
31#define MAX_ADDR_LEN 7
32
33
34/* This structure defines an ethernet arp header. */
35
36/* ARP protocol opcodes. */
37#define ARPOP_REQUEST 1 /* ARP request. */
38#define ARPOP_REPLY 2 /* ARP reply. */
39#define ARPOP_RREQUEST 3 /* RARP request. */
40#define ARPOP_RREPLY 4 /* RARP reply. */
41#define ARPOP_InREQUEST 8 /* InARP request. */
42#define ARPOP_InREPLY 9 /* InARP reply. */
43#define ARPOP_NAK 10 /* (ATM)ARP NAK. */
44
45/* See RFC 826 for protocol description. ARP packets are variable
46 in size; the arphdr structure defines the fixed-length portion.
47 Protocol type values are the same as those for 10 Mb/s Ethernet.
48 It is followed by the variable-sized fields ar_sha, arp_spa,
49 arp_tha and arp_tpa in that order, according to the lengths
50 specified. Field names used correspond to RFC 826. */
51
52struct arphdr
53 {
54 unsigned short int ar_hrd; /* Format of hardware address. */
55 unsigned short int ar_pro; /* Format of protocol address. */
56 unsigned char ar_hln; /* Length of hardware address. */
57 unsigned char ar_pln; /* Length of protocol address. */
58 unsigned short int ar_op; /* ARP opcode (command). */
59#if 0
60 /* Ethernet looks like this : This bit is variable sized
61 however... */
62 unsigned char __ar_sha[ETH_ALEN]; /* Sender hardware address. */
63 unsigned char __ar_sip[4]; /* Sender IP address. */
64 unsigned char __ar_tha[ETH_ALEN]; /* Target hardware address. */
65 unsigned char __ar_tip[4]; /* Target IP address. */
66#endif
67 };
68
69
70/* ARP protocol HARDWARE identifiers. */
71#define ARPHRD_NETROM 0 /* From KA9Q: NET/ROM pseudo. */
72#define ARPHRD_ETHER 1 /* Ethernet 10/100Mbps. */
73#define ARPHRD_EETHER 2 /* Experimental Ethernet. */
74#define ARPHRD_AX25 3 /* AX.25 Level 2. */
75#define ARPHRD_PRONET 4 /* PROnet token ring. */
76#define ARPHRD_CHAOS 5 /* Chaosnet. */
77#define ARPHRD_IEEE802 6 /* IEEE 802.2 Ethernet/TR/TB. */
78#define ARPHRD_ARCNET 7 /* ARCnet. */
79#define ARPHRD_APPLETLK 8 /* APPLEtalk. */
80#define ARPHRD_DLCI 15 /* Frame Relay DLCI. */
81#define ARPHRD_ATM 19 /* ATM. */
82#define ARPHRD_METRICOM 23 /* Metricom STRIP (new IANA id). */
83#define ARPHRD_IEEE1394 24 /* IEEE 1394 IPv4 - RFC 2734. */
84#define ARPHRD_EUI64 27 /* EUI-64. */
85#define ARPHRD_INFINIBAND 32 /* InfiniBand. */
86
87/* Dummy types for non ARP hardware */
88#define ARPHRD_SLIP 256
89#define ARPHRD_CSLIP 257
90#define ARPHRD_SLIP6 258
91#define ARPHRD_CSLIP6 259
92#define ARPHRD_RSRVD 260 /* Notional KISS type. */
93#define ARPHRD_ADAPT 264
94#define ARPHRD_ROSE 270
95#define ARPHRD_X25 271 /* CCITT X.25. */
96#define ARPHRD_HWX25 272 /* Boards with X.25 in firmware. */
97#define ARPHRD_CAN 280 /* Controller Area Network. */
98#define ARPHRD_MCTP 290
99#define ARPHRD_PPP 512
100#define ARPHRD_CISCO 513 /* Cisco HDLC. */
101#define ARPHRD_HDLC ARPHRD_CISCO
102#define ARPHRD_LAPB 516 /* LAPB. */
103#define ARPHRD_DDCMP 517 /* Digital's DDCMP. */
104#define ARPHRD_RAWHDLC 518 /* Raw HDLC. */
105#define ARPHRD_RAWIP 519 /* Raw IP. */
106
107#define ARPHRD_TUNNEL 768 /* IPIP tunnel. */
108#define ARPHRD_TUNNEL6 769 /* IPIP6 tunnel. */
109#define ARPHRD_FRAD 770 /* Frame Relay Access Device. */
110#define ARPHRD_SKIP 771 /* SKIP vif. */
111#define ARPHRD_LOOPBACK 772 /* Loopback device. */
112#define ARPHRD_LOCALTLK 773 /* Localtalk device. */
113#define ARPHRD_FDDI 774 /* Fiber Distributed Data Interface. */
114#define ARPHRD_BIF 775 /* AP1000 BIF. */
115#define ARPHRD_SIT 776 /* sit0 device - IPv6-in-IPv4. */
116#define ARPHRD_IPDDP 777 /* IP-in-DDP tunnel. */
117#define ARPHRD_IPGRE 778 /* GRE over IP. */
118#define ARPHRD_PIMREG 779 /* PIMSM register interface. */
119#define ARPHRD_HIPPI 780 /* High Performance Parallel I'face. */
120#define ARPHRD_ASH 781 /* (Nexus Electronics) Ash. */
121#define ARPHRD_ECONET 782 /* Acorn Econet. */
122#define ARPHRD_IRDA 783 /* Linux-IrDA. */
123#define ARPHRD_FCPP 784 /* Point to point fibrechanel. */
124#define ARPHRD_FCAL 785 /* Fibrechanel arbitrated loop. */
125#define ARPHRD_FCPL 786 /* Fibrechanel public loop. */
126#define ARPHRD_FCFABRIC 787 /* Fibrechanel fabric. */
127#define ARPHRD_IEEE802_TR 800 /* Magic type ident for TR. */
128#define ARPHRD_IEEE80211 801 /* IEEE 802.11. */
129#define ARPHRD_IEEE80211_PRISM 802 /* IEEE 802.11 + Prism2 header. */
130#define ARPHRD_IEEE80211_RADIOTAP 803 /* IEEE 802.11 + radiotap header. */
131#define ARPHRD_IEEE802154 804 /* IEEE 802.15.4 header. */
132#define ARPHRD_IEEE802154_PHY 805 /* IEEE 802.15.4 PHY header. */
133
134#define ARPHRD_VOID 0xFFFF /* Void type, nothing is known. */
135#define ARPHRD_NONE 0xFFFE /* Zero header length. */
136
137
138/* ARP ioctl request. */
139struct arpreq
140 {
141 struct sockaddr arp_pa; /* Protocol address. */
142 struct sockaddr arp_ha; /* Hardware address. */
143 int arp_flags; /* Flags. */
144 struct sockaddr arp_netmask; /* Netmask (only for proxy arps). */
145 char arp_dev[16];
146 };
147
148struct arpreq_old
149 {
150 struct sockaddr arp_pa; /* Protocol address. */
151 struct sockaddr arp_ha; /* Hardware address. */
152 int arp_flags; /* Flags. */
153 struct sockaddr arp_netmask; /* Netmask (only for proxy arps). */
154 };
155
156/* ARP Flag values. */
157#define ATF_COM 0x02 /* Completed entry (ha valid). */
158#define ATF_PERM 0x04 /* Permanent entry. */
159#define ATF_PUBL 0x08 /* Publish entry. */
160#define ATF_USETRAILERS 0x10 /* Has requested trailers. */
161#define ATF_NETMASK 0x20 /* Want to use a netmask (only
162 for proxy entries). */
163#define ATF_DONTPUB 0x40 /* Don't answer this addresses. */
164#define ATF_MAGIC 0x80 /* Automatically added entry. */
165
166
167/* Support for the user space arp daemon, arpd. */
168#define ARPD_UPDATE 0x01
169#define ARPD_LOOKUP 0x02
170#define ARPD_FLUSH 0x03
171
172struct arpd_request
173 {
174 unsigned short int req; /* Request type. */
175 uint32_t ip; /* IP address of entry. */
176 unsigned long int dev; /* Device entry is tied to. */
177 unsigned long int stamp;
178 unsigned long int updated;
179 unsigned char ha[MAX_ADDR_LEN]; /* Hardware address. */
180 };
181
182__END_DECLS
183
184#endif /* net/if_arp.h */