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/* Determine whether interfaces use native transport. Linux version.
Copyright (C) 2007-2021 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 <assert.h>
#include <errno.h>
#include <ifaddrs.h>
#include <stddef.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <net/if.h>
#include <net/if_arp.h>
#include <sys/ioctl.h>
#include <asm/types.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include <not-cancel.h>
#include "netlinkaccess.h"
void
__check_native (uint32_t a1_index, int *a1_native,
uint32_t a2_index, int *a2_native)
{
int fd = __socket (PF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, 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)
return;
pid_t pid = nladdr.nl_pid;
struct req
{
struct nlmsghdr nlh;
struct rtgenmsg g;
/* struct rtgenmsg consists of a single byte. This means there
are three bytes of padding included in the REQ definition.
We make them explicit here. */
char pad[3];
} req;
req.nlh.nlmsg_len = sizeof (req);
req.nlh.nlmsg_type = RTM_GETLINK;
req.nlh.nlmsg_flags = NLM_F_ROOT | NLM_F_MATCH | NLM_F_REQUEST;
req.nlh.nlmsg_pid = 0;
req.nlh.nlmsg_seq = time_now ();
req.g.rtgen_family = AF_UNSPEC;
assert (sizeof (req) - offsetof (struct req, pad) == 3);
memset (req.pad, '\0', sizeof (req.pad));
memset (&nladdr, '\0', sizeof (nladdr));
nladdr.nl_family = AF_NETLINK;
#ifdef PAGE_SIZE
/* Help the compiler optimize out the malloc call if PAGE_SIZE
is constant and smaller or equal to PTHREAD_STACK_MIN/4. */
const size_t buf_size = PAGE_SIZE;
#else
const size_t buf_size = __getpagesize ();
#endif
bool use_malloc = false;
char *buf;
if (__libc_use_alloca (buf_size))
buf = alloca (buf_size);
else
{
buf = malloc (buf_size);
if (buf != NULL)
use_malloc = true;
else
goto out_fail;
}
struct iovec iov = { buf, buf_size };
if (TEMP_FAILURE_RETRY (__sendto (fd, (void *) &req, sizeof (req), 0,
(struct sockaddr *) &nladdr,
sizeof (nladdr))) < 0)
goto out_fail;
bool done = false;
do
{
struct msghdr msg =
{
.msg_name = (void *) &nladdr,
.msg_namelen = sizeof (nladdr),
.msg_iov = &iov,
.msg_iovlen = 1,
.msg_control = NULL,
.msg_controllen = 0,
.msg_flags = 0
};
ssize_t read_len = TEMP_FAILURE_RETRY (__recvmsg (fd, &msg, 0));
__netlink_assert_response (fd, read_len);
if (read_len < 0)
goto out_fail;
if (msg.msg_flags & MSG_TRUNC)
goto out_fail;
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_NEWLINK)
{
struct ifinfomsg *ifim = (struct ifinfomsg *) NLMSG_DATA (nlmh);
int native = (ifim->ifi_type != ARPHRD_TUNNEL6
&& ifim->ifi_type != ARPHRD_TUNNEL
&& ifim->ifi_type != ARPHRD_SIT);
if (a1_index == ifim->ifi_index)
{
*a1_native = native;
a1_index = 0xffffffffu;
}
if (a2_index == ifim->ifi_index)
{
*a2_native = native;
a2_index = 0xffffffffu;
}
if (a1_index == 0xffffffffu
&& a2_index == 0xffffffffu)
goto out;
}
else if (nlmh->nlmsg_type == NLMSG_DONE)
/* We found the end, leave the loop. */
done = true;
}
}
while (! done);
out:
__close_nocancel_nostatus (fd);
return;
out_fail:
if (use_malloc)
free (buf);
}
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