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/* Determine protocol families for which interfaces exist. Linux version.
Copyright (C) 2003 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, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
#include <errno.h>
#include <ifaddrs.h>
#include <netdb.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <sys/socket.h>
#include <asm/types.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include "kernel-features.h"
static int
make_request (int fd, pid_t pid, bool *seen_ipv4, bool *seen_ipv6)
{
struct
{
struct nlmsghdr nlh;
struct rtgenmsg g;
} req;
struct sockaddr_nl nladdr;
req.nlh.nlmsg_len = sizeof (req);
req.nlh.nlmsg_type = RTM_GETADDR;
req.nlh.nlmsg_flags = NLM_F_ROOT | NLM_F_MATCH | NLM_F_REQUEST;
req.nlh.nlmsg_pid = 0;
req.nlh.nlmsg_seq = time (NULL);
req.g.rtgen_family = AF_UNSPEC;
memset (&nladdr, '\0', sizeof (nladdr));
nladdr.nl_family = AF_NETLINK;
if (TEMP_FAILURE_RETRY (__sendto (fd, (void *) &req, sizeof (req), 0,
(struct sockaddr *) &nladdr,
sizeof (nladdr))) < 0)
return -1;
*seen_ipv4 = false;
*seen_ipv6 = false;
bool done = false;
char buf[4096];
struct iovec iov = { buf, sizeof (buf) };
do
{
struct msghdr msg =
{
(void *) &nladdr, sizeof (nladdr),
&iov, 1,
NULL, 0,
0
};
ssize_t read_len = TEMP_FAILURE_RETRY (__recvmsg (fd, &msg, 0));
if (read_len < 0)
return -1;
if (msg.msg_flags & MSG_TRUNC)
return -1;
struct nlmsghdr *nlmh;
for (nlmh = (struct nlmsghdr *) buf;
NLMSG_OK (nlmh, (size_t) read_len);
nlmh = (struct nlmsghdr *) NLMSG_NEXT (nlmh, read_len))
{
if (nladdr.nl_pid != 0 || (pid_t) nlmh->nlmsg_pid != pid
|| nlmh->nlmsg_seq != req.nlh.nlmsg_seq)
continue;
if (nlmh->nlmsg_type == RTM_NEWADDR)
{
struct ifaddrmsg *ifam = (struct ifaddrmsg *) NLMSG_DATA (nlmh);
switch (ifam->ifa_family)
{
case AF_INET:
*seen_ipv4 = true;
break;
case AF_INET6:
*seen_ipv6 = true;
break;
default:
/* Ignore. */
break;
}
}
else if (nlmh->nlmsg_type == NLMSG_DONE)
/* We found the end, leave the loop. */
done = true;
else ;
}
}
while (! done);
__close (fd);
return 0;
}
/* We don't know if we have NETLINK support compiled in in our
Kernel. */
#if __ASSUME_NETLINK_SUPPORT == 0
/* Define in ifaddrs.h. */
extern int __no_netlink_support attribute_hidden;
#else
# define __no_netlink_support 0
#endif
void
attribute_hidden
__check_pf (bool *seen_ipv4, bool *seen_ipv6)
{
if (! __no_netlink_support)
{
int fd = __socket (PF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
struct sockaddr_nl nladdr;
memset (&nladdr, '\0', sizeof (nladdr));
nladdr.nl_family = AF_NETLINK;
socklen_t addr_len = sizeof (nladdr);
if (fd >= 0
&& __bind (fd, (struct sockaddr *) &nladdr, sizeof (nladdr)) == 0
&& __getsockname (fd, (struct sockaddr *) &nladdr, &addr_len) == 0
&& make_request (fd, nladdr.nl_pid, seen_ipv4, seen_ipv6) == 0)
/* It worked. */
return;
if (fd >= 0)
__close (fd);
#if __ASSUME_NETLINK_SUPPORT == 0
/* Remember that there is no netlink support. */
__no_netlink_support = 1;
#else
/* We cannot determine what interfaces are available. Be
pessimistic. */
*seen_ipv4 = true;
*seen_ipv6 = true;
#endif
}
#if __ASSUME_NETLINK_SUPPORT == 0
/* No netlink. Get the interface list via getifaddrs. */
struct ifaddrs *ifa = NULL;
if (getifaddrs (&ifa) != 0)
{
/* We cannot determine what interfaces are available. Be
pessimistic. */
*seen_ipv4 = true;
*seen_ipv6 = true;
return;
}
*seen_ipv4 = false;
*seen_ipv6 = false;
struct ifaddrs *runp;
for (runp = ifa; runp != NULL; runp = runp->ifa_next)
if (runp->ifa_addr->sa_family == PF_INET)
*seen_ipv4 = true;
else if (runp->ifa_addr->sa_family == PF_INET6)
*seen_ipv6 = true;
(void) freeifaddrs (ifa);
#endif
}
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