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



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(g)  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 mes-
              sage. 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(k)

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



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