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 auxilliary 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)

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

Linux Man Page                                     14 May 1999                                        NETLINK(3)