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

                                                                                    libnetlink(3)