198 lines
4.6 KiB
Groff
198 lines
4.6 KiB
Groff
.TH libnetlink 3
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.SH NAME
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libnetlink \- A library for accessing the netlink service
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.SH SYNOPSIS
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.nf
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#include <asm/types.h>
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.br
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#include <libnetlink.h>
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.br
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#include <linux/netlink.h>
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.br
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#include <linux/rtnetlink.h>
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.sp
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int rtnl_open(struct rtnl_handle *rth, unsigned subscriptions)
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.sp
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int rtnl_wilddump_request(struct rtnl_handle *rth, int family, int type)
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.sp
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int rtnl_send(struct rtnl_handle *rth, char *buf, int len)
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.sp
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int rtnl_dump_request(struct rtnl_handle *rth, int type, void *req, int len)
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.sp
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int rtnl_dump_filter(struct rtnl_handle *rth,
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int (*filter)(struct sockaddr_nl *, struct nlmsghdr *n, void *),
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void *arg1,
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int (*junk)(struct sockaddr_nl *,struct nlmsghdr *n, void *),
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void *arg2)
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.sp
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int rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n, pid_t peer,
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unsigned groups, struct nlmsghdr *answer,
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.br
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int (*junk)(struct sockaddr_nl *,struct nlmsghdr *n, void *),
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.br
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void *jarg)
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.sp
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int rtnl_listen(struct rtnl_handle *rtnl,
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int (*handler)(struct sockaddr_nl *,struct nlmsghdr *n, void *),
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void *jarg)
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.sp
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int rtnl_from_file(FILE *rtnl,
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int (*handler)(struct sockaddr_nl *,struct nlmsghdr *n, void *),
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void *jarg)
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.sp
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int addattr32(struct nlmsghdr *n, int maxlen, int type, __u32 data)
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.sp
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int addattr_l(struct nlmsghdr *n, int maxlen, int type, void *data, int alen)
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.sp
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int rta_addattr32(struct rtattr *rta, int maxlen, int type, __u32 data)
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.sp
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int rta_addattr_l(struct rtattr *rta, int maxlen, int type, void *data, int alen)
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.SH DESCRIPTION
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libnetlink provides a higher level interface to
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.BR rtnetlink(7).
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The read functions return 0 on success and a negative errno on failure.
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The send functions return the amount of data sent, or -1 on error.
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.TP
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rtnl_open
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Open a rtnetlink socket and save the state into the
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.B rth
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handle. This handle is passed to all subsequent calls.
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.B subscriptions
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is a bitmap of the rtnetlink multicast groups the socket will be
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a member of.
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.TP
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rtnl_wilddump_request
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Request a full dump of the
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.B type
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database for
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.B family
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addresses.
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.B type
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is a rtnetlink message type.
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.\" XXX
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.TP
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rtnl_dump_request
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Request a full dump of the
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.B type
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data buffer into
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.B buf
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with maximum length of
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.B len.
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.B type
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is a rtnetlink message type.
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.TP
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rtnl_dump_filter
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Receive netlink data after a request and filter it.
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The
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.B filter
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callback checks if the received message is wanted. It gets the source
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address of the message, the message itself and
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.B arg1
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as arguments. 0 as return means that the filter passed, a negative
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value is returned
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by
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.I rtnl_dump_filter
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in case of error. NULL for
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.I filter
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means to not use a filter.
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.B junk
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is used to filter messages not destined to the local socket.
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Only one message bundle is received. Unless there is no message
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pending, this function does not block.
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.TP
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rtnl_listen
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Receive netlink data after a request and pass it to
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.I handler.
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.B handler
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is a callback that gets the message source address, the message itself,
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and the
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.B jarg
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cookie as arguments. It will get called for all received messages.
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Only one message bundle is received. Unless there is no message
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pending this function does not block.
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.TP
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rtnl_from_file
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Works like
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.I rtnl_listen,
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but reads a netlink message bundle from the file
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.B file
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and passes the messages to
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.B handler
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for parsing. The file contains raw data as received from a rtnetlink socket.
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.PP
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The following functions are useful to construct custom rtnetlink messages. For
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simple database dumping with filtering it is better to use the higher level
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functions above. See
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.BR rtnetlink(3)
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and
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.BR netlink(3)
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on how to generate a rtnetlink message. The following utility functions
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require a continuous buffer that already contains a netlink message header
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and a rtnetlink request.
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.TP
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rtnl_send
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Send the rtnetlink message in
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.B buf
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of length
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.B len
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to handle
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.B rth.
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.TP
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addattr32
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Add a __u32 attribute of type
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.B type
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and with value
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.B data
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to netlink message
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.B n,
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which is part of a buffer of length
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.B maxlen.
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.TP
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addattr_l
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Add a variable length attribute of type
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.B type
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and with value
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.B data
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and
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.B alen
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length to netlink message
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.B n,
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which is part of a buffer of length
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.B maxlen.
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.B data
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is copied.
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.TP
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rta_addattr32
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Initialize the rtnetlink attribute
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.B rta
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with a __u32 data value.
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.TP
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rta_addattr32
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Initialize the rtnetlink attribute
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.B rta
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with a variable length data value.
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.SH BUGS
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The functions sometimes use fprintf and exit when a fatal error occurs.
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This library should be named librtnetlink.
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.SH AUTHORS
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netlink/rtnetlink was designed and writen by Alexey Kuznetsov.
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Andi Kleen wrote the man page.
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.SH SEE ALSO
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.BR netlink(7),
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.BR rtnetlink(7)
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.br
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/usr/include/linux/rtnetlink.h
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