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