/* Return point to next ancillary data entry in message header.

   Copyright (C) 1997-2018 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 <stddef.h>

#include <sys/socket.h>

struct cmsghdr *

__cmsg_nxthdr (struct msghdr *mhdr, struct cmsghdr *cmsg)

{

  if ((size_t) cmsg->cmsg_len < sizeof (struct cmsghdr))

    /* The kernel header does this so there may be a reason.  */

    return NULL;

  cmsg = (struct cmsghdr *) ((unsigned char *) cmsg

			     + CMSG_ALIGN (cmsg->cmsg_len));

  if ((unsigned char *) (cmsg + 1) > ((unsigned char *) mhdr->msg_control

				      + mhdr->msg_controllen)

      || ((unsigned char *) cmsg + CMSG_ALIGN (cmsg->cmsg_len)

	  > ((unsigned char *) mhdr->msg_control + mhdr->msg_controllen)))

    /* No more entries.  */

    return NULL;

  return cmsg;

}

libc_hidden_def (__cmsg_nxthdr)