167 lines
4.4 KiB
C
167 lines
4.4 KiB
C
/* getifaddrs -- get names and addresses of all network interfaces
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Copyright (C) 2002-2022 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <ifaddrs.h>
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#include <net/if.h>
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#include <sys/socket.h>
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#include <sys/ioctl.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <string.h>
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#include <errno.h>
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#include <netinet/in.h>
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#include "ifreq.h"
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/* Create a linked list of `struct ifaddrs' structures, one for each
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network interface on the host machine. If successful, store the
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list in *IFAP and return 0. On errors, return -1 and set `errno'. */
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int
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__getifaddrs (struct ifaddrs **ifap)
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{
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/* This implementation handles only IPv4 interfaces.
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The various ioctls below will only work on an AF_INET socket.
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Some different mechanism entirely must be used for IPv6. */
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int fd = __socket (AF_INET, SOCK_DGRAM, 0);
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struct ifreq *ifreqs;
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int nifs;
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if (fd < 0)
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return -1;
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__ifreq (&ifreqs, &nifs, fd);
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if (ifreqs == NULL) /* XXX doesn't distinguish error vs none */
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{
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__close (fd);
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return -1;
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}
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/* Now we have the list of interfaces and each one's address.
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Put it into the expected format and fill in the remaining details. */
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if (nifs == 0)
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*ifap = NULL;
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else
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{
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struct
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{
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struct ifaddrs ia;
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struct sockaddr addr, netmask, broadaddr;
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char name[IF_NAMESIZE];
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} *storage;
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struct ifreq *ifr;
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int i;
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storage = malloc (nifs * sizeof storage[0]);
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if (storage == NULL)
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{
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__close (fd);
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__if_freereq (ifreqs, nifs);
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return -1;
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}
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i = 0;
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ifr = ifreqs;
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do
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{
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/* Fill in pointers to the storage we've already allocated. */
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storage[i].ia.ifa_next = &storage[i + 1].ia;
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storage[i].ia.ifa_addr = &storage[i].addr;
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/* Now copy the information we already have from SIOCGIFCONF. */
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storage[i].ia.ifa_name = strncpy (storage[i].name, ifr->ifr_name,
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sizeof storage[i].name);
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storage[i].addr = ifr->ifr_addr;
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/* The SIOCGIFCONF call filled in only the name and address.
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Now we must also ask for the other information we need. */
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if (__ioctl (fd, SIOCGIFFLAGS, ifr) < 0)
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break;
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storage[i].ia.ifa_flags = ifr->ifr_flags;
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ifr->ifr_addr = storage[i].addr;
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if (__ioctl (fd, SIOCGIFNETMASK, ifr) < 0)
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storage[i].ia.ifa_netmask = NULL;
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else
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{
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storage[i].ia.ifa_netmask = &storage[i].netmask;
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storage[i].netmask = ifr->ifr_netmask;
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}
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if (ifr->ifr_flags & IFF_BROADCAST)
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{
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ifr->ifr_addr = storage[i].addr;
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if (__ioctl (fd, SIOCGIFBRDADDR, ifr) < 0)
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storage[i].ia.ifa_broadaddr = NULL;
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{
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storage[i].ia.ifa_broadaddr = &storage[i].broadaddr;
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storage[i].broadaddr = ifr->ifr_broadaddr;
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}
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}
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else if (ifr->ifr_flags & IFF_POINTOPOINT)
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{
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ifr->ifr_addr = storage[i].addr;
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if (__ioctl (fd, SIOCGIFDSTADDR, ifr) < 0)
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storage[i].ia.ifa_broadaddr = NULL;
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else
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{
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storage[i].ia.ifa_broadaddr = &storage[i].broadaddr;
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storage[i].broadaddr = ifr->ifr_dstaddr;
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}
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}
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else
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storage[i].ia.ifa_broadaddr = NULL;
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storage[i].ia.ifa_data = NULL; /* Nothing here for now. */
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ifr = __if_nextreq (ifr);
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} while (++i < nifs);
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if (i < nifs) /* Broke out early on error. */
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{
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__close (fd);
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free (storage);
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__if_freereq (ifreqs, nifs);
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return -1;
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}
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storage[i - 1].ia.ifa_next = NULL;
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*ifap = &storage[0].ia;
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__close (fd);
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__if_freereq (ifreqs, nifs);
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}
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return 0;
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}
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weak_alias (__getifaddrs, getifaddrs)
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libc_hidden_def (__getifaddrs)
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#ifndef getifaddrs
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libc_hidden_weak (getifaddrs)
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#endif
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void
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__freeifaddrs (struct ifaddrs *ifa)
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{
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free (ifa);
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}
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weak_alias (__freeifaddrs, freeifaddrs)
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libc_hidden_def (__freeifaddrs)
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libc_hidden_weak (freeifaddrs)
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