inet/ifaddrs.h

   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 */