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1/* net/if.h -- declarations for inquiring about network interfaces
2 Copyright (C) 1997-2025 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#ifndef _NET_IF_H
20#define _NET_IF_H 1
21
22#include <features.h>
23
24#ifdef __USE_MISC
25# include <sys/types.h>
26# include <sys/socket.h>
27#endif
28
29
30/* Length of interface name. */
31#define IF_NAMESIZE 16
32
33struct if_nameindex
34 {
35 unsigned int if_index; /* 1, 2, ... */
36 char *if_name; /* null terminated name: "eth0", ... */
37 };
38
39
40#ifdef __USE_MISC
41/* Standard interface flags. */
42enum
43 {
44 IFF_UP = 0x1, /* Interface is up. */
45# define IFF_UP IFF_UP
46 IFF_BROADCAST = 0x2, /* Broadcast address valid. */
47# define IFF_BROADCAST IFF_BROADCAST
48 IFF_DEBUG = 0x4, /* Turn on debugging. */
49# define IFF_DEBUG IFF_DEBUG
50 IFF_LOOPBACK = 0x8, /* Is a loopback net. */
51# define IFF_LOOPBACK IFF_LOOPBACK
52 IFF_POINTOPOINT = 0x10, /* Interface is point-to-point link. */
53# define IFF_POINTOPOINT IFF_POINTOPOINT
54 IFF_NOTRAILERS = 0x20, /* Avoid use of trailers. */
55# define IFF_NOTRAILERS IFF_NOTRAILERS
56 IFF_RUNNING = 0x40, /* Resources allocated. */
57# define IFF_RUNNING IFF_RUNNING
58 IFF_NOARP = 0x80, /* No address resolution protocol. */
59# define IFF_NOARP IFF_NOARP
60 IFF_PROMISC = 0x100, /* Receive all packets. */
61# define IFF_PROMISC IFF_PROMISC
62
63 /* Not supported */
64 IFF_ALLMULTI = 0x200, /* Receive all multicast packets. */
65# define IFF_ALLMULTI IFF_ALLMULTI
66
67 IFF_MASTER = 0x400, /* Master of a load balancer. */
68# define IFF_MASTER IFF_MASTER
69 IFF_SLAVE = 0x800, /* Slave of a load balancer. */
70# define IFF_SLAVE IFF_SLAVE
71
72 IFF_MULTICAST = 0x1000, /* Supports multicast. */
73# define IFF_MULTICAST IFF_MULTICAST
74
75 IFF_PORTSEL = 0x2000, /* Can set media type. */
76# define IFF_PORTSEL IFF_PORTSEL
77 IFF_AUTOMEDIA = 0x4000, /* Auto media select active. */
78# define IFF_AUTOMEDIA IFF_AUTOMEDIA
79 IFF_DYNAMIC = 0x8000 /* Dialup device with changing addresses. */
80# define IFF_DYNAMIC IFF_DYNAMIC
81 };
82
83/* The ifaddr structure contains information about one address of an
84 interface. They are maintained by the different address families,
85 are allocated and attached when an address is set, and are linked
86 together so all addresses for an interface can be located. */
87
88struct ifaddr
89 {
90 struct sockaddr ifa_addr; /* Address of interface. */
91 union
92 {
93 struct sockaddr ifu_broadaddr;
94 struct sockaddr ifu_dstaddr;
95 } ifa_ifu;
96 struct iface *ifa_ifp; /* Back-pointer to interface. */
97 struct ifaddr *ifa_next; /* Next address for interface. */
98 };
99
100# define ifa_broadaddr ifa_ifu.ifu_broadaddr /* broadcast address */
101# define ifa_dstaddr ifa_ifu.ifu_dstaddr /* other end of link */
102
103/* Device mapping structure. I'd just gone off and designed a
104 beautiful scheme using only loadable modules with arguments for
105 driver options and along come the PCMCIA people 8)
106
107 Ah well. The get() side of this is good for WDSETUP, and it'll be
108 handy for debugging things. The set side is fine for now and being
109 very small might be worth keeping for clean configuration. */
110
111struct ifmap
112 {
113 unsigned long int mem_start;
114 unsigned long int mem_end;
115 unsigned short int base_addr;
116 unsigned char irq;
117 unsigned char dma;
118 unsigned char port;
119 /* 3 bytes spare */
120 };
121
122/* Interface request structure used for socket ioctl's. All interface
123 ioctl's must have parameter definitions which begin with ifr_name.
124 The remainder may be interface specific. */
125
126struct ifreq
127 {
128# define IFHWADDRLEN 6
129# define IFNAMSIZ IF_NAMESIZE
130 union
131 {
132 char ifrn_name[IFNAMSIZ]; /* Interface name, e.g. "en0". */
133 } ifr_ifrn;
134
135 union
136 {
137 struct sockaddr ifru_addr;
138 struct sockaddr ifru_dstaddr;
139 struct sockaddr ifru_broadaddr;
140 struct sockaddr ifru_netmask;
141 struct sockaddr ifru_hwaddr;
142 short int ifru_flags;
143 int ifru_ivalue;
144 int ifru_mtu;
145 struct ifmap ifru_map;
146 char ifru_slave[IFNAMSIZ]; /* Just fits the size */
147 char ifru_newname[IFNAMSIZ];
148 __caddr_t ifru_data;
149 } ifr_ifru;
150 };
151# define ifr_name ifr_ifrn.ifrn_name /* interface name */
152# define ifr_hwaddr ifr_ifru.ifru_hwaddr /* MAC address */
153# define ifr_addr ifr_ifru.ifru_addr /* address */
154# define ifr_dstaddr ifr_ifru.ifru_dstaddr /* other end of p-p lnk */
155# define ifr_broadaddr ifr_ifru.ifru_broadaddr /* broadcast address */
156# define ifr_netmask ifr_ifru.ifru_netmask /* interface net mask */
157# define ifr_flags ifr_ifru.ifru_flags /* flags */
158# define ifr_metric ifr_ifru.ifru_ivalue /* metric */
159# define ifr_mtu ifr_ifru.ifru_mtu /* mtu */
160# define ifr_map ifr_ifru.ifru_map /* device map */
161# define ifr_slave ifr_ifru.ifru_slave /* slave device */
162# define ifr_data ifr_ifru.ifru_data /* for use by interface */
163# define ifr_ifindex ifr_ifru.ifru_ivalue /* interface index */
164# define ifr_bandwidth ifr_ifru.ifru_ivalue /* link bandwidth */
165# define ifr_qlen ifr_ifru.ifru_ivalue /* queue length */
166# define ifr_newname ifr_ifru.ifru_newname /* New name */
167# define _IOT_ifreq _IOT(_IOTS(char),IFNAMSIZ,_IOTS(char),16,0,0)
168# define _IOT_ifreq_short _IOT(_IOTS(char),IFNAMSIZ,_IOTS(short),1,0,0)
169# define _IOT_ifreq_int _IOT(_IOTS(char),IFNAMSIZ,_IOTS(int),1,0,0)
170
171
172/* Structure used in SIOCGIFCONF request. Used to retrieve interface
173 configuration for machine (useful for programs which must know all
174 networks accessible). */
175
176struct ifconf
177 {
178 int ifc_len; /* Size of buffer. */
179 union
180 {
181 __caddr_t ifcu_buf;
182 struct ifreq *ifcu_req;
183 } ifc_ifcu;
184 };
185# define ifc_buf ifc_ifcu.ifcu_buf /* Buffer address. */
186# define ifc_req ifc_ifcu.ifcu_req /* Array of structures. */
187# define _IOT_ifconf _IOT(_IOTS(struct ifconf),1,0,0,0,0) /* not right */
188#endif /* Misc. */
189
190__BEGIN_DECLS
191
192/* Convert an interface name to an index, and vice versa. */
193extern unsigned int if_nametoindex (const char *__ifname) __THROW;
194extern char *if_indextoname (unsigned int __ifindex,
195 char __ifname[IF_NAMESIZE]) __THROW
196 __attr_access ((__write_only__, 2));
197
198/* Return a list of all interfaces and their indices. */
199extern struct if_nameindex *if_nameindex (void) __THROW;
200
201/* Free the data returned from if_nameindex. */
202extern void if_freenameindex (struct if_nameindex *__ptr) __THROW;
203
204__END_DECLS
205
206#endif /* net/if.h */