NAME
netlink - Netlink macros
SYNOPSIS
#include <asm/types.h>
#include <linux/netlink.h>
I int NLMSG_ALIGN(size_t len );
I int NLMSG_LENGTH(size_t len );
I int NLMSG_SPACE(size_t len );
I void *NLMSG_DATA(struct nlmsghdr * nlh );
I struct nlmsghdr *NLMSG_NEXT(struct nlmsghdr * nlh , int len );
I int NLMSG_OK(struct nlmsghdr * nlh , int len );
I 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
only be accessed using these macros.
NLMSG_ALIGN
Round the length of a netlink message up to align it properly.
NLMSG_LENGTH
Given the payload length,
R len ,
this macro returns the aligned length to store in the
nlmsg_len
field of the
R 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
R 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 length parameter 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 ok to parse.
NLMSG_PAYLOAD
Return the length of the payload associated with the
R nlmsghdr .
CONFORMING
These macros are non-standard Linux extensions.
NOTES
It is often better to use netlink via
libnetlink
than via the low level kernel interface.
SEE ALSO
and ftp://ftp.inr.ac.ru/ip-routing/iproute2* for libnetlink
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