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/* getifaddrs -- get names and addresses of all network interfaces
Copyright (C) 2002-2022 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
<https://www.gnu.org/licenses/>. */
#include <ifaddrs.h>
#include <net/if.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <netinet/in.h>
#include "ifreq.h"
/* 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'. */
int
__getifaddrs (struct ifaddrs **ifap)
{
/* This implementation handles only IPv4 interfaces.
The various ioctls below will only work on an AF_INET socket.
Some different mechanism entirely must be used for IPv6. */
int fd = __socket (AF_INET, SOCK_DGRAM, 0);
struct ifreq *ifreqs;
int nifs;
if (fd < 0)
return -1;
__ifreq (&ifreqs, &nifs, fd);
if (ifreqs == NULL) /* XXX doesn't distinguish error vs none */
{
__close (fd);
return -1;
}
/* Now we have the list of interfaces and each one's address.
Put it into the expected format and fill in the remaining details. */
if (nifs == 0)
*ifap = NULL;
else
{
struct
{
struct ifaddrs ia;
struct sockaddr addr, netmask, broadaddr;
char name[IF_NAMESIZE];
} *storage;
struct ifreq *ifr;
int i;
storage = malloc (nifs * sizeof storage[0]);
if (storage == NULL)
{
__close (fd);
__if_freereq (ifreqs, nifs);
return -1;
}
i = 0;
ifr = ifreqs;
do
{
/* Fill in pointers to the storage we've already allocated. */
storage[i].ia.ifa_next = &storage[i + 1].ia;
storage[i].ia.ifa_addr = &storage[i].addr;
/* Now copy the information we already have from SIOCGIFCONF. */
storage[i].ia.ifa_name = strncpy (storage[i].name, ifr->ifr_name,
sizeof storage[i].name);
storage[i].addr = ifr->ifr_addr;
/* The SIOCGIFCONF call filled in only the name and address.
Now we must also ask for the other information we need. */
if (__ioctl (fd, SIOCGIFFLAGS, ifr) < 0)
break;
storage[i].ia.ifa_flags = ifr->ifr_flags;
ifr->ifr_addr = storage[i].addr;
if (__ioctl (fd, SIOCGIFNETMASK, ifr) < 0)
storage[i].ia.ifa_netmask = NULL;
else
{
storage[i].ia.ifa_netmask = &storage[i].netmask;
storage[i].netmask = ifr->ifr_netmask;
}
if (ifr->ifr_flags & IFF_BROADCAST)
{
ifr->ifr_addr = storage[i].addr;
if (__ioctl (fd, SIOCGIFBRDADDR, ifr) < 0)
storage[i].ia.ifa_broadaddr = NULL;
{
storage[i].ia.ifa_broadaddr = &storage[i].broadaddr;
storage[i].broadaddr = ifr->ifr_broadaddr;
}
}
else if (ifr->ifr_flags & IFF_POINTOPOINT)
{
ifr->ifr_addr = storage[i].addr;
if (__ioctl (fd, SIOCGIFDSTADDR, ifr) < 0)
storage[i].ia.ifa_broadaddr = NULL;
else
{
storage[i].ia.ifa_broadaddr = &storage[i].broadaddr;
storage[i].broadaddr = ifr->ifr_dstaddr;
}
}
else
storage[i].ia.ifa_broadaddr = NULL;
storage[i].ia.ifa_data = NULL; /* Nothing here for now. */
ifr = __if_nextreq (ifr);
} while (++i < nifs);
if (i < nifs) /* Broke out early on error. */
{
__close (fd);
free (storage);
__if_freereq (ifreqs, nifs);
return -1;
}
storage[i - 1].ia.ifa_next = NULL;
*ifap = &storage[0].ia;
__close (fd);
__if_freereq (ifreqs, nifs);
}
return 0;
}
weak_alias (__getifaddrs, getifaddrs)
libc_hidden_def (__getifaddrs)
#ifndef getifaddrs
libc_hidden_weak (getifaddrs)
#endif
void
__freeifaddrs (struct ifaddrs *ifa)
{
free (ifa);
}
weak_alias (__freeifaddrs, freeifaddrs)
libc_hidden_def (__freeifaddrs)
libc_hidden_weak (freeifaddrs)
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