Representation of a netlink socket. More...

Allocation
struct nl_sock *	nl_socket_alloc (void)
	Allocate new netlink socket. More...

struct nl_sock *	nl_socket_alloc_cb (struct nl_cb *cb)
	Allocate new socket with custom callbacks. More...

void	nl_socket_free (struct nl_sock *sk)
	Free a netlink socket. More...

Sequence Numbers
void	nl_socket_disable_seq_check (struct nl_sock *sk)
	Disable sequence number checking. More...

unsigned int	nl_socket_use_seq (struct nl_sock *sk)
	Use next sequence number. More...

void	nl_socket_disable_auto_ack (struct nl_sock *sk)
	Disable automatic request for ACK. More...

void	nl_socket_enable_auto_ack (struct nl_sock *sk)
	Enable automatic request for ACK (default) More...

Source Idenficiation
uint32_t	nl_socket_get_local_port (const struct nl_sock *sk)

void	nl_socket_set_local_port (struct nl_sock *sk, uint32_t port)
	Set local port of socket. More...

Group Subscriptions
int	nl_socket_add_memberships (struct nl_sock *sk, int group,...)
	Join groups. More...

int	nl_socket_add_membership (struct nl_sock *sk, int group)

int	nl_socket_drop_memberships (struct nl_sock *sk, int group,...)
	Leave groups. More...

int	nl_socket_drop_membership (struct nl_sock *sk, int group)

void	nl_join_groups (struct nl_sock *sk, int groups)
	Join multicast groups (deprecated) More...

Peer Identfication
uint32_t	nl_socket_get_peer_port (const struct nl_sock *sk)

void	nl_socket_set_peer_port (struct nl_sock *sk, uint32_t port)

uint32_t	nl_socket_get_peer_groups (const struct nl_sock *sk)

void	nl_socket_set_peer_groups (struct nl_sock *sk, uint32_t groups)

File Descriptor
int	nl_socket_get_fd (const struct nl_sock *sk)
	Return the file descriptor of the backing socket. More...

int	nl_socket_set_fd (struct nl_sock *sk, int protocol, int fd)
	Set the socket file descriptor externally which initializes the socket similar to nl_connect(). More...

int	nl_socket_set_nonblocking (const struct nl_sock *sk)
	Set file descriptor of socket to non-blocking state. More...

void	nl_socket_enable_msg_peek (struct nl_sock *sk)
	Enable use of MSG_PEEK when reading from socket. More...

void	nl_socket_disable_msg_peek (struct nl_sock *sk)
	Disable use of MSG_PEEK when reading from socket. More...

Callback Handler
struct nl_cb *	nl_socket_get_cb (const struct nl_sock *sk)

void	nl_socket_set_cb (struct nl_sock sk, struct nl_cb cb)

int	nl_socket_modify_cb (struct nl_sock sk, enum nl_cb_type type, enum nl_cb_kind kind, nl_recvmsg_msg_cb_t func, void arg)
	Modify the callback handler associated with the socket. More...

int	nl_socket_modify_err_cb (struct nl_sock sk, enum nl_cb_kind kind, nl_recvmsg_err_cb_t func, void arg)
	Modify the error callback handler associated with the socket. More...

Utilities
int	nl_socket_set_buffer_size (struct nl_sock *sk, int rxbuf, int txbuf)
	Set socket buffer size of netlink socket. More...

int	nl_socket_set_msg_buf_size (struct nl_sock *sk, size_t bufsize)
	Set default message buffer size of netlink socket. More...

size_t	nl_socket_get_msg_buf_size (struct nl_sock *sk)
	Get default message buffer size of netlink socket. More...

int	nl_socket_set_passcred (struct nl_sock *sk, int state)
	Enable/disable credential passing on netlink socket. More...

int	nl_socket_recv_pktinfo (struct nl_sock *sk, int state)
	Enable/disable receival of additional packet information. More...

Detailed Description

Representation of a netlink socket.

Related sections in the development guide:

Netlink Sockets (Netlink Core Library Development Guide)

Header

#include <netlink/socket.h>

Function Documentation

◆ nl_socket_alloc()

struct nl_sock * nl_socket_alloc ( void )

Allocate new netlink socket.

Returns: Newly allocated netlink socket or NULL.

Definition at line 200 of file socket.c.

References nl_cb_alloc().

Referenced by nl_cache_mngr_alloc().

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◆ nl_socket_alloc_cb()

struct nl_sock * nl_socket_alloc_cb ( struct nl_cb * cb )

Allocate new socket with custom callbacks.

Parameters

cb	Callback handler

The reference to the callback handler is taken into account automatically, it is released again upon calling nl_socket_free().

Returns: Newly allocted socket handle or NULL.

Definition at line 226 of file socket.c.

◆ nl_socket_free()

void nl_socket_free ( struct nl_sock * sk )

Free a netlink socket.

Parameters

sk	Netlink socket.

Definition at line 238 of file socket.c.

Referenced by nl_cache_mngr_alloc(), and nl_cache_mngr_free().

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◆ nl_socket_disable_seq_check()

void nl_socket_disable_seq_check ( struct nl_sock * sk )

Disable sequence number checking.

Parameters

sk	Netlink socket.

Disables checking of sequence numbers on the netlink socket This is required to allow messages to be processed which were not requested by a preceding request message, e.g. netlink events.

Note: This function modifies the NL_CB_SEQ_CHECK configuration in the callback handle associated with the socket.

Definition at line 277 of file socket.c.

References NL_CB_CUSTOM, NL_CB_SEQ_CHECK, and nl_cb_set().

Referenced by nl_cache_mngr_alloc().

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◆ nl_socket_use_seq()

unsigned int nl_socket_use_seq ( struct nl_sock * sk )

Use next sequence number.

Parameters

sk	Netlink socket.

Uses the next available sequence number and increases the counter by one for subsequent calls.

Returns: Unique serial sequence number

Definition at line 292 of file socket.c.

◆ nl_socket_disable_auto_ack()

void nl_socket_disable_auto_ack ( struct nl_sock * sk )

Disable automatic request for ACK.

Parameters

sk	Netlink socket.

The default behaviour of a socket is to request an ACK for each message sent to allow for the caller to synchronize to the completion of the netlink operation. This function disables this behaviour and will result in requests being sent which will not have the NLM_F_ACK flag set automatically. However, it is still possible for the caller to set the NLM_F_ACK flag explicitely.

Definition at line 309 of file socket.c.

◆ nl_socket_enable_auto_ack()

void nl_socket_enable_auto_ack ( struct nl_sock * sk )

Enable automatic request for ACK (default)

Parameters

sk	Netlink socket.

See also: nl_socket_disable_auto_ack

Definition at line 319 of file socket.c.

◆ nl_socket_get_local_port()

uint32_t nl_socket_get_local_port ( const struct nl_sock * sk )

Definition at line 359 of file socket.c.

◆ nl_socket_set_local_port()

void nl_socket_set_local_port	(	struct nl_sock *	sk,
		uint32_t	port
	)

Set local port of socket.

Parameters

sk	Netlink socket.
port	Local port identifier

Assigns a local port identifier to the socket.

If port is 0, the port is reset to 'unspecified' as it is after newly calling nl_socket_alloc(). Unspecified means, that the port will be generated automatically later on first use (either on nl_socket_get_local_port() or nl_connect()).

Definition at line 398 of file socket.c.

Referenced by nl_connect(), and nl_socket_set_fd().

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◆ nl_socket_add_memberships()

int nl_socket_add_memberships	(	struct nl_sock *	sk,
		int	group,
			...
	)

Join groups.

Parameters

sk	Netlink socket
group	Group identifier

Joins the specified groups using the modern socket option which is available since kernel version 2.6.14. It allows joining an almost arbitary number of groups without limitation. The list of groups has to be terminated by 0 (NFNLGRP_NONE).

Make sure to use the correct group definitions as the older bitmask definitions for nl_join_groups() are likely to still be present for backward compatibility reasons.

Returns: 0 on success or a negative error code.

Definition at line 429 of file socket.c.

◆ nl_socket_add_membership()

int nl_socket_add_membership	(	struct nl_sock *	sk,
		int	group
	)

Definition at line 462 of file socket.c.

◆ nl_socket_drop_memberships()

int nl_socket_drop_memberships	(	struct nl_sock *	sk,
		int	group,
			...
	)

Leave groups.

Parameters

sk	Netlink socket
group	Group identifier

Leaves the specified groups using the modern socket option which is available since kernel version 2.6.14. The list of groups has to terminated by 0 (NFNLGRP_NONE).

See also: nl_socket_add_membership

Returns: 0 on success or a negative error code.

Definition at line 479 of file socket.c.

◆ nl_socket_drop_membership()

int nl_socket_drop_membership	(	struct nl_sock *	sk,
		int	group
	)

Definition at line 512 of file socket.c.

◆ nl_join_groups()

void nl_join_groups	(	struct nl_sock *	sk,
		int	groups
	)

Join multicast groups (deprecated)

Parameters

sk	Netlink socket.
groups	Bitmask of groups to join.

This function defines the old way of joining multicast group which has to be done prior to calling nl_connect(). It works on any kernel version but is very limited as only 32 groups can be joined.

Definition at line 527 of file socket.c.

◆ nl_socket_get_peer_port()

uint32_t nl_socket_get_peer_port ( const struct nl_sock * sk )

Definition at line 540 of file socket.c.

◆ nl_socket_set_peer_port()

void nl_socket_set_peer_port	(	struct nl_sock *	sk,
		uint32_t	port
	)

Definition at line 545 of file socket.c.

◆ nl_socket_get_peer_groups()

uint32_t nl_socket_get_peer_groups ( const struct nl_sock * sk )

Definition at line 550 of file socket.c.

◆ nl_socket_set_peer_groups()

void nl_socket_set_peer_groups	(	struct nl_sock *	sk,
		uint32_t	groups
	)

Definition at line 555 of file socket.c.

◆ nl_socket_get_fd()

int nl_socket_get_fd ( const struct nl_sock * sk )

Return the file descriptor of the backing socket.

Parameters

sk	Netlink socket

Only valid after calling nl_connect() to create and bind the respective socket.

Returns: File descriptor or -1 if not available.

Definition at line 578 of file socket.c.

Referenced by nl_cache_mngr_data_ready(), nl_cache_mngr_get_fd(), and nl_cache_mngr_poll().

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◆ nl_socket_set_fd()

int nl_socket_set_fd	(	struct nl_sock *	sk,
		int	protocol,
		int	fd
	)

Set the socket file descriptor externally which initializes the socket similar to nl_connect().

Parameters

sk	Netlink socket (required)
protocol	The socket protocol (optional). Linux 2.6.32 supports the socket option SO_PROTOCOL. In this case, you can set protocol to a negative value and let it autodetect. If you set it to a non-negative value, the detected protocol must match the one provided. To support older kernels, you must specify the protocol.
fd	Socket file descriptor to use (required)

Set the socket file descriptor. @fd must be valid and bind'ed.

This is an alternative to nl_connect(). nl_connect() creates, binds and sets the socket. With this function you can set the socket to an externally created file descriptor.

See also: nl_connect()

Returns: 0 on success or a negative error code. On error, @fd is not closed but possibly unusable.

Return values

-NLE_BAD_SOCK	Netlink socket is already connected
-NLE_INVAL	Socket is of unexpected type

Definition at line 610 of file socket.c.

References nl_socket_set_local_port().

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◆ nl_socket_set_nonblocking()

int nl_socket_set_nonblocking ( const struct nl_sock * sk )

Set file descriptor of socket to non-blocking state.

Parameters

sk	Netlink socket.

Returns: 0 on success or a negative error code.

Definition at line 697 of file socket.c.

Referenced by nl_cache_mngr_alloc().

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◆ nl_socket_enable_msg_peek()

void nl_socket_enable_msg_peek ( struct nl_sock * sk )

Enable use of MSG_PEEK when reading from socket.

Parameters

sk	Netlink socket.

See also NL_CAPABILITY_NL_RECVMSGS_PEEK_BY_DEFAULT capability

Definition at line 717 of file socket.c.

◆ nl_socket_disable_msg_peek()

void nl_socket_disable_msg_peek ( struct nl_sock * sk )

Disable use of MSG_PEEK when reading from socket.

Parameters

sk	Netlink socket.

See also NL_CAPABILITY_NL_RECVMSGS_PEEK_BY_DEFAULT capability

Definition at line 728 of file socket.c.

◆ nl_socket_get_cb()

struct nl_cb * nl_socket_get_cb ( const struct nl_sock * sk )

Definition at line 741 of file socket.c.

◆ nl_socket_set_cb()

void nl_socket_set_cb	(	struct nl_sock *	sk,
		struct nl_cb *	cb
	)

Definition at line 746 of file socket.c.

◆ nl_socket_modify_cb()

int nl_socket_modify_cb	(	struct nl_sock *	sk,
		enum nl_cb_type	type,
		enum nl_cb_kind	kind,
		nl_recvmsg_msg_cb_t	func,
		void *	arg
	)

Modify the callback handler associated with the socket.

Parameters

sk	Netlink socket.
type	which type callback to set
kind	kind of callback
func	callback function
arg	argument to be passed to callback function

See also: nl_cb_set

Definition at line 765 of file socket.c.

References nl_cb_set().

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◆ nl_socket_modify_err_cb()

int nl_socket_modify_err_cb	(	struct nl_sock *	sk,
		enum nl_cb_kind	kind,
		nl_recvmsg_err_cb_t	func,
		void *	arg
	)

Modify the error callback handler associated with the socket.

Parameters

sk	Netlink socket.
kind	kind of callback
func	callback function
arg	argument to be passed to callback function

See also: nl_cb_err

Definition at line 781 of file socket.c.

References nl_cb_err().

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◆ nl_socket_set_buffer_size()

int nl_socket_set_buffer_size	(	struct nl_sock *	sk,
		int	rxbuf,
		int	txbuf
	)

Set socket buffer size of netlink socket.

Parameters

sk	Netlink socket.
rxbuf	New receive socket buffer size in bytes.
txbuf	New transmit socket buffer size in bytes.

Sets the socket buffer size of a netlink socket to the specified values rxbuf and txbuf. Providing a value of 0 assumes a good default value.

Note: It is not required to call this function prior to nl_connect().

Returns: 0 on success or a negative error code.

Definition at line 807 of file socket.c.

Referenced by nl_connect().

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◆ nl_socket_set_msg_buf_size()

int nl_socket_set_msg_buf_size	(	struct nl_sock *	sk,
		size_t	bufsize
	)

Set default message buffer size of netlink socket.

Parameters

sk	Netlink socket.
bufsize	Default message buffer size in bytes.

Sets the default message buffer size to the specified length in bytes. The default message buffer size limits the maximum message size the socket will be able to receive. It is generally recommneded to specify a buffer size no less than the size of a memory page.

Setting the @bufsize to zero means to use a default of 4 times getpagesize().

When MSG_PEEK is enabled, the buffer size is used for the initial choice of the buffer while peeking. It still makes sense to choose an optimal value to avoid realloc().

When MSG_PEEK is disabled, the buffer size is important because a too small size will lead to failure of receiving the message via nl_recvmsgs().

By default, MSG_PEEK is enabled unless the user calls either nl_socket_disable_msg_peek()/ nl_socket_enable_msg_peek() or sets the message buffer size to a positive value. See capability NL_CAPABILITY_NL_RECVMSGS_PEEK_BY_DEFAULT for that.

Returns: 0 on success or a negative error code.

Definition at line 864 of file socket.c.

◆ nl_socket_get_msg_buf_size()

size_t nl_socket_get_msg_buf_size ( struct nl_sock * sk )

Get default message buffer size of netlink socket.

Parameters

sk	Netlink socket.

Returns: Size of default message buffer.

Definition at line 877 of file socket.c.

◆ nl_socket_set_passcred()

int nl_socket_set_passcred	(	struct nl_sock *	sk,
		int	state
	)

Enable/disable credential passing on netlink socket.

Parameters

sk	Netlink socket.
state	New state (0 - disabled, 1 - enabled)

Returns: 0 on success or a negative error code

Definition at line 889 of file socket.c.

◆ nl_socket_recv_pktinfo()

int nl_socket_recv_pktinfo	(	struct nl_sock *	sk,
		int	state
	)

Enable/disable receival of additional packet information.

Parameters

sk	Netlink socket.
state	New state (0 - disabled, 1 - enabled)

Returns: 0 on success or a negative error code

Definition at line 919 of file socket.c.

Allocation

Sequence Numbers

Source Idenficiation

Group Subscriptions

Peer Identfication

File Descriptor

Callback Handler

Utilities

Detailed Description

Header

Function Documentation

◆ nl_socket_alloc()

◆ nl_socket_alloc_cb()

◆ nl_socket_free()

◆ nl_socket_disable_seq_check()

◆ nl_socket_use_seq()

◆ nl_socket_disable_auto_ack()

◆ nl_socket_enable_auto_ack()

◆ nl_socket_get_local_port()

◆ nl_socket_set_local_port()

◆ nl_socket_add_memberships()

◆ nl_socket_add_membership()

◆ nl_socket_drop_memberships()

◆ nl_socket_drop_membership()

◆ nl_join_groups()

◆ nl_socket_get_peer_port()

◆ nl_socket_set_peer_port()

◆ nl_socket_get_peer_groups()

◆ nl_socket_set_peer_groups()

◆ nl_socket_get_fd()

◆ nl_socket_set_fd()

◆ nl_socket_set_nonblocking()

◆ nl_socket_enable_msg_peek()

◆ nl_socket_disable_msg_peek()

◆ nl_socket_get_cb()

◆ nl_socket_set_cb()

◆ nl_socket_modify_cb()

◆ nl_socket_modify_err_cb()

◆ nl_socket_set_buffer_size()

◆ nl_socket_set_msg_buf_size()

◆ nl_socket_get_msg_buf_size()

◆ nl_socket_set_passcred()

◆ nl_socket_recv_pktinfo()