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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 <stdint.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 <stdbool.h>

#include <sys/uio.h>

#include "config.h"

#include "local.h"

#define __ASSUME_NETLINK_SUPPORT 1

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,

        };

      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

}