NAME | SYNOPSIS | DESCRIPTION | CONFORMING TO | NOTES | SEE ALSO | COLOPHON

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

NAME         top

       netlink - Netlink macros

SYNOPSIS         top

       #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         top

       <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 be accessed using only these macros.

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

       NLMSG_LENGTH()
              Given the payload length, len, this macro returns the aligned
              length to store in the nlmsg_len field of the 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
              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 len argument 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 is in
              a form suitable for parsing.

       NLMSG_PAYLOAD()
              Return the length of the payload associated with the nlmsghdr.

CONFORMING TO         top

       These macros are nonstandard Linux extensions.

NOTES         top

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

SEE ALSO         top

       libnetlink(3), netlink(7)

COLOPHON         top

       This page is part of release 4.08 of the Linux man-pages project.  A
       description of the project, information about reporting bugs, and the
       latest version of this page, can be found at
       https://www.kernel.org/doc/man-pages/.

GNU                              2014-03-20                       NETLINK(3)