1 /* ifaddrs.h -- declarations for getting network interface addresses 2 Copyright (C) 2002 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, write to the Free 17 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 18 02111-1307 USA. */ 19 20 #ifndef _IFADDRS_H 21 #define _IFADDRS_H 1 22 23 #include <features.h> 24 #include <sys/socket.h> 25 26 __BEGIN_DECLS 27 28 /* The `getifaddrs' function generates a linked list of these structures. 29 Each element of the list describes one network interface. */ 30 struct ifaddrs 31 { 32 struct ifaddrs *ifa_next; /* Pointer to the next structure. */ 33 34 char *ifa_name; /* Name of this network interface. */ 35 unsigned int ifa_flags; /* Flags as from SIOCGIFFLAGS ioctl. */ 36 37 struct sockaddr *ifa_addr; /* Network address of this interface. */ 38 struct sockaddr *ifa_netmask; /* Netmask of this interface. */ 39 union 40 { 41 /* At most one of the following two is valid. If the IFF_BROADCAST 42 bit is set in `ifa_flags', then `ifa_broadaddr' is valid. If the 43 IFF_POINTOPOINT bit is set, then `ifa_dstaddr' is valid. 44 It is never the case that both these bits are set at once. */ 45 struct sockaddr *ifu_broadaddr; /* Broadcast address of this interface. */ 46 struct sockaddr *ifu_dstaddr; /* Point-to-point destination address. */ 47 } ifa_ifu; 48 /* These very same macros are defined by <net/if.h> for `struct ifaddr'. 49 So if they are defined already, the existing definitions will be fine. */ 50 # ifndef ifa_broadaddr 51 # define ifa_broadaddr ifa_ifu.ifu_broadaddr 52 # endif 53 # ifndef ifa_dstaddr 54 # define ifa_dstaddr ifa_ifu.ifu_dstaddr 55 # endif 56 57 void *ifa_data; /* Address-specific data (may be unused). */ 58 }; 59 60 61 /* Create a linked list of `struct ifaddrs' structures, one for each 62 network interface on the host machine. If successful, store the 63 list in *IFAP and return 0. On errors, return -1 and set `errno'. 64 65 The storage returned in *IFAP is allocated dynamically and can 66 only be properly freed by passing it to `freeifaddrs'. */ 67 extern int getifaddrs (struct ifaddrs **__ifap) __THROW; 68 69 /* Reclaim the storage allocated by a previous `getifaddrs' call. */ 70 extern void freeifaddrs (struct ifaddrs *__ifa) __THROW; 71 72 __END_DECLS 73 74 #endif /* ifaddrs.h */ 75
