glibc (2.38)
1 /* ifaddrs.h -- declarations for getting network interface addresses
2 Copyright (C) 2002-2023 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 _IFADDRS_H
20 #define _IFADDRS_H 1
21
22 #include <features.h>
23 #include <sys/socket.h>
24
25 __BEGIN_DECLS
26
27 /* The `getifaddrs' function generates a linked list of these structures.
28 Each element of the list describes one network interface. */
29 struct ifaddrs
30 {
31 struct ifaddrs *ifa_next; /* Pointer to the next structure. */
32
33 char *ifa_name; /* Name of this network interface. */
34 unsigned int ifa_flags; /* Flags as from SIOCGIFFLAGS ioctl. */
35
36 struct sockaddr *ifa_addr; /* Network address of this interface. */
37 struct sockaddr *ifa_netmask; /* Netmask of this interface. */
38 union
39 {
40 /* At most one of the following two is valid. If the IFF_BROADCAST
41 bit is set in `ifa_flags', then `ifa_broadaddr' is valid. If the
42 IFF_POINTOPOINT bit is set, then `ifa_dstaddr' is valid.
43 It is never the case that both these bits are set at once. */
44 struct sockaddr *ifu_broadaddr; /* Broadcast address of this interface. */
45 struct sockaddr *ifu_dstaddr; /* Point-to-point destination address. */
46 } ifa_ifu;
47 /* These very same macros are defined by <net/if.h> for `struct ifaddr'.
48 So if they are defined already, the existing definitions will be fine. */
49 # ifndef ifa_broadaddr
50 # define ifa_broadaddr ifa_ifu.ifu_broadaddr
51 # endif
52 # ifndef ifa_dstaddr
53 # define ifa_dstaddr ifa_ifu.ifu_dstaddr
54 # endif
55
56 void *ifa_data; /* Address-specific data (may be unused). */
57 };
58
59
60 /* Create a linked list of `struct ifaddrs' structures, one for each
61 network interface on the host machine. If successful, store the
62 list in *IFAP and return 0. On errors, return -1 and set `errno'.
63
64 The storage returned in *IFAP is allocated dynamically and can
65 only be properly freed by passing it to `freeifaddrs'. */
66 extern int getifaddrs (struct ifaddrs **__ifap) __THROW;
67
68 /* Reclaim the storage allocated by a previous `getifaddrs' call. */
69 extern void freeifaddrs (struct ifaddrs *__ifa) __THROW;
70
71 __END_DECLS
72
73 #endif /* ifaddrs.h */
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