/* Determine whether interfaces use native transport.  Linux version.

   Copyright (C) 2007-2018 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

   <http://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 (NULL);

  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);

}