netlink(3) — Linux manual page

netlink(3)              Library Functions Manual              netlink(3)

NAME

       netlink - Netlink macros

LIBRARY

       Standard C library (libc, -lc)

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

       <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.

VERSIONS

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

STANDARDS

       Linux.

SEE ALSO

       libnetlink(3), netlink(7)

COLOPHON

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Linux man-pages 6.9.1          2024-05-02                     netlink(3)

Pages that refer to this page: libnetlink(3), rtnetlink(3), netlink(7), sock_diag(7)

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