libnetlink


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 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.


              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 mes-
              sages 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, 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  mes-
       sages.  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

       Kleen wrote the man page.


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



                                                                 libnetlink(3)
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