NETLINK(3)						     Linux Programmer's Manual							NETLINK(3)

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

       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 only accessed using these macros.

       NLMSG_ALIGN
	      Round the length of a netlink message up to align it properly.

       NLMSG_LENGTH
	      Gets the payload length as argument and returns the aligned length to store in the nlmsg_len field of the nlmsghdr.

       NLMSG_SPACE
	      Return the number of bytes a netlink message with payload of the passed length 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 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 nlmsghdr.

NOTES

       It is often better to use netlink via libnetlink than via the low level kernel interface.

SEE ALSO

       netlink(7)

       and ftp://ftp.inr.ac.ru/ip-routing/iproute2* for libnetlink

Linux Man Page							    1999-05-14								NETLINK(3)