NETLINK
Section: Linux Programmer's Manual (3)
Updated: 2014-03-20
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NAME
netlink - Netlink macros
SYNOPSIS
#include <asm/types.h>
#include <linux/netlink.h>
int NLMSG_ALIGN(size_t len);
int NLMSG_LENGTH(size_t len);
int NLMSG_SPACE(size_t len);
void *NLMSG_DATA(struct nlmsghdr *nlh);
struct nlmsghdr *NLMSG_NEXT(struct nlmsghdr *nlh, int len);
int NLMSG_OK(struct nlmsghdr *nlh, int len);
int NLMSG_PAYLOAD(struct nlmsghdr *nlh, int len);
DESCRIPTION
<linux/netlink.h>
defines several standard macros to access or create a netlink datagram.
They are similar in spirit to the macros defined in
cmsg(3)
for auxiliary data.
The buffer passed to and from a netlink socket should
be accessed using only these macros.
- NLMSG_ALIGN()
-
Round the length of a netlink message up to align it properly.
- NLMSG_LENGTH()
-
Given the payload length,
len,
this macro returns the aligned length to store in the
nlmsg_len
field of the
nlmsghdr.
- NLMSG_SPACE()
-
Return the number of bytes that a netlink message with payload of
len
would occupy.
- NLMSG_DATA()
-
Return a pointer to the payload associated with the passed
nlmsghdr.
-
-
NLMSG_NEXT()
Get the next
nlmsghdr
in a multipart message.
The caller must check if the current
nlmsghdr
didn't have the
NLMSG_DONE
set---this function doesn't return NULL on end.
The
len
argument is an lvalue containing the remaining length
of the message buffer.
This macro decrements it by the length of the message header.
- NLMSG_OK()
-
Return true if the netlink message is not truncated and
is in a form suitable for parsing.
- NLMSG_PAYLOAD()
-
Return the length of the payload associated with the
nlmsghdr.
CONFORMING TO
These macros are nonstandard Linux extensions.
NOTES
It is often better to use netlink via
libnetlink
than via the low-level kernel interface.
SEE ALSO
libnetlink(3),
netlink(7)
COLOPHON
This page is part of release 5.11 of the Linux
man-pages
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
https://www.kernel.org/doc/man-pages/.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- CONFORMING TO
-
- NOTES
-
- SEE ALSO
-
- COLOPHON
-
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