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 ar-
guments. 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, an-
scillary data, the message itself, and the jarg cookie as argu-
ments. 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
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)
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