1/* Return point to next ancillary data entry in message header.
2 Copyright (C) 1997-2020 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#include <stddef.h>
20#include <sys/socket.h>
21
22
23struct cmsghdr *
24__cmsg_nxthdr (struct msghdr *mhdr, struct cmsghdr *cmsg)
25{
26 if ((size_t) cmsg->cmsg_len < sizeof (struct cmsghdr))
27 /* The kernel header does this so there may be a reason. */
28 return NULL;
29
30 cmsg = (struct cmsghdr *) ((unsigned char *) cmsg
31 + CMSG_ALIGN (cmsg->cmsg_len));
32 if ((unsigned char *) (cmsg + 1) > ((unsigned char *) mhdr->msg_control
33 + mhdr->msg_controllen)
34 || ((unsigned char *) cmsg + CMSG_ALIGN (cmsg->cmsg_len)
35 > ((unsigned char *) mhdr->msg_control + mhdr->msg_controllen)))
36 /* No more entries. */
37 return NULL;
38 return cmsg;
39}
40libc_hidden_def (__cmsg_nxthdr)
41