libnetlink(3) — Linux manual page

libnetlink(3)           Library Functions Manual           libnetlink(3)

NAME

       libnetlink - A library for accessing the netlink service

SYNOPSIS

       #include <asm/types.h>
       #include <libnetlink.h>
       #include <linux/netlink.h>
       #include <linux/rtnetlink.h>

       int rtnl_open(struct rtnl_handle *rth, unsigned subscriptions)

       int rtnl_wilddump_request(struct rtnl_handle *rth, int family, int type)

       int rtnl_send(struct rtnl_handle *rth, char *buf, int len)

       int rtnl_dump_request(struct rtnl_handle *rth, int type, void *req, int len)

       int rtnl_dump_filter(struct rtnl_handle *rth,
                      int (*filter)(struct sockaddr_nl *, struct nlmsghdr *n, void *),
                      void *arg1,
                      int (*junk)(struct sockaddr_nl *,struct nlmsghdr *n, void *),
                      void *arg2)

       int rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n, pid_t peer,
                  unsigned groups, struct nlmsghdr *answer,
                  int (*junk)(struct sockaddr_nl *,struct nlmsghdr *n, void *),
                  void *jarg)

       int rtnl_listen(struct rtnl_handle *rtnl,
                  int (*handler)(struct sockaddr_nl *, struct rtnl_ctrl_data *,
                           struct nlmsghdr *n, void *),
                  void *jarg)

       int rtnl_from_file(FILE *rtnl,
                  int (*handler)(struct sockaddr_nl *,struct nlmsghdr *n, void *),
                  void *jarg)

       int addattr32(struct nlmsghdr *n, int maxlen, int type, __u32 data)

       int addattr_l(struct nlmsghdr *n, int maxlen, int type, void *data, int alen)

       int rta_addattr32(struct rtattr *rta, int maxlen, int type, __u32 data)

       int rta_addattr_l(struct rtattr *rta, int maxlen, int type, void *data, int alen)

DESCRIPTION

       libnetlink provides a higher level interface to rtnetlink(7).
       The read functions return 0 on success and a negative errno on
       failure.  The send functions return the amount of data sent, or
       -1 on error.

       rtnl_open
              Open a rtnetlink socket and save the state into the rth
              handle. This handle is passed to all subsequent calls.
              subscriptions is a bitmap of the rtnetlink multicast
              groups the socket will be a member of.

       rtnl_wilddump_request
              Request a full dump of the type database for family
              addresses.  type is a rtnetlink message type.

       rtnl_dump_request
              Request a full dump of the type data buffer into buf with
              maximum length of len.  type is a rtnetlink message type.

       rtnl_dump_filter
              Receive netlink data after a request and filter it.  The
              filter callback checks if the received message is wanted.
              It gets the source address of the message, the message
              itself and arg1 as arguments. 0 as return means that the
              filter passed, a negative value is returned by
              rtnl_dump_filter in case of error. NULL for filter means
              to not use a filter.  junk is used to filter messages not
              destined to the local socket.  Only one message bundle is
              received. If there is a message pending, this function
              does not block.

       rtnl_listen
              Receive netlink data after a request and pass it to
              handler.  handler is a callback that gets the message
              source address, anscillary data, the message itself, and
              the jarg cookie as arguments. It will get called for all
              received messages.  Only one message bundle is received.
              If there is a message pending this function does not
              block.

       rtnl_from_file
              Works like rtnl_listen, but reads a netlink message bundle
              from the file file and passes the messages to handler for
              parsing. The file should contain raw data as received from
              a rtnetlink socket.

       The following functions are useful to construct custom rtnetlink
       messages. For simple database dumping with filtering it is better
       to use the higher level functions above. See rtnetlink(3) and
       netlink(3) on how to generate a rtnetlink message. The following
       utility functions require a continuous buffer that already
       contains a netlink message header and a rtnetlink request.

       rtnl_send
              Send the rtnetlink message in buf of length len to handle
              rth.

       addattr32
              Add a __u32 attribute of type type and with value data to
              netlink message n, which is part of a buffer of length
              maxlen.

       addattr_l
              Add a variable length attribute of type type and with
              value data and alen length to netlink message n, which is
              part of a buffer of length maxlen.  data is copied.

       rta_addattr32
              Initialize the rtnetlink attribute rta with a __u32 data
              value.

       rta_addattr32
              Initialize the rtnetlink attribute rta with a variable
              length data value.

BUGS

       This library is meant for internal use, use libmnl for new
       programs.

       The functions sometimes use fprintf and exit when a fatal error
       occurs.  This library should be named librtnetlink.

AUTHORS

       netlink/rtnetlink was designed and written by Alexey Kuznetsov.
       Andi Kleen wrote the man page.

SEE ALSO

       netlink(7), rtnetlink(7)
       /usr/include/linux/rtnetlink.h

COLOPHON

       This page is part of the iproute2 (utilities for controlling
       TCP/IP networking and traffic) project.  Information about the
       project can be found at 
       ⟨http://www.linuxfoundation.org/collaborate/workgroups/networking/iproute2⟩.
       If you have a bug report for this manual page, send it to
       netdev@vger.kernel.org, shemminger@osdl.org.  This page was
       obtained from the project's upstream Git repository
       ⟨https://git.kernel.org/pub/scm/network/iproute2/iproute2.git⟩ on
       2024-06-14.  (At that time, the date of the most recent commit
       that was found in the repository was 2024-06-11.)  If you
       discover any rendering problems in this HTML version of the page,
       or you believe there is a better or more up-to-date source for
       the page, or you have corrections or improvements to the
       information in this COLOPHON (which is not part of the original
       manual page), send a mail to man-pages@man7.org

                                                           libnetlink(3)

Pages that refer to this page: netlink(3)

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