/* ifaddrs.h -- declarations for getting network interface addresses

   Copyright (C) 2002-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

#ifndef _IFADDRS_H

#define _IFADDRS_H	1

#include <features.h>

#include <sys/socket.h>

__BEGIN_DECLS

/* The `getifaddrs' function generates a linked list of these structures.

   Each element of the list describes one network interface.  */

struct ifaddrs

{

  struct ifaddrs *ifa_next;	/* Pointer to the next structure.  */

  char *ifa_name;		/* Name of this network interface.  */

  unsigned int ifa_flags;	/* Flags as from SIOCGIFFLAGS ioctl.  */

  struct sockaddr *ifa_addr;	/* Network address of this interface.  */

  struct sockaddr *ifa_netmask; /* Netmask of this interface.  */

  union

  {

    /* At most one of the following two is valid.  If the IFF_BROADCAST

       bit is set in `ifa_flags', then `ifa_broadaddr' is valid.  If the

       IFF_POINTOPOINT bit is set, then `ifa_dstaddr' is valid.

       It is never the case that both these bits are set at once.  */

    struct sockaddr *ifu_broadaddr; /* Broadcast address of this interface. */

    struct sockaddr *ifu_dstaddr; /* Point-to-point destination address.  */

  } ifa_ifu;

  /* These very same macros are defined by <net/if.h> for `struct ifaddr'.

     So if they are defined already, the existing definitions will be fine.  */

# ifndef ifa_broadaddr

#  define ifa_broadaddr	ifa_ifu.ifu_broadaddr

# endif

# ifndef ifa_dstaddr

#  define ifa_dstaddr	ifa_ifu.ifu_dstaddr

# endif

  void *ifa_data;		/* Address-specific data (may be unused).  */

};

/* Create a linked list of `struct ifaddrs' structures, one for each

   network interface on the host machine.  If successful, store the

   list in *IFAP and return 0.  On errors, return -1 and set `errno'.

   The storage returned in *IFAP is allocated dynamically and can

   only be properly freed by passing it to `freeifaddrs'.  */

extern int getifaddrs (struct ifaddrs **__ifap) __THROW;

/* Reclaim the storage allocated by a previous `getifaddrs' call.  */

extern void freeifaddrs (struct ifaddrs *__ifa)  __THROW;

__END_DECLS

#endif /* ifaddrs.h */