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 */