libnl 1.1
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Handle representing a netlink socket. More...
Allocation | |
struct nl_handle * | nl_handle_alloc (void) |
Allocate new netlink socket handle. | |
struct nl_handle * | nl_handle_alloc_cb (struct nl_cb *cb) |
Allocate new socket handle with custom callbacks. | |
void | nl_handle_destroy (struct nl_handle *handle) |
Destroy netlink handle. | |
Sequence Numbers | |
void | nl_disable_sequence_check (struct nl_handle *handle) |
Disable sequence number checking. | |
unsigned int | nl_socket_use_seq (struct nl_handle *handle) |
Use next sequence number. | |
Source Idenficiation | |
uint32_t | nl_socket_get_local_port (struct nl_handle *handle) |
void | nl_socket_set_local_port (struct nl_handle *handle, uint32_t port) |
Set local port of socket. | |
Group Subscriptions | |
int | nl_socket_add_membership (struct nl_handle *handle, int group) |
Join a group. | |
int | nl_socket_drop_membership (struct nl_handle *handle, int group) |
Leave a group. | |
void | nl_join_groups (struct nl_handle *handle, int groups) |
Join multicast groups (deprecated) | |
Peer Identfication | |
uint32_t | nl_socket_get_peer_port (struct nl_handle *handle) |
void | nl_socket_set_peer_port (struct nl_handle *handle, uint32_t port) |
File Descriptor | |
int | nl_socket_get_fd (struct nl_handle *handle) |
int | nl_socket_set_nonblocking (struct nl_handle *handle) |
Set file descriptor of socket handle to non-blocking state. | |
void | nl_socket_enable_msg_peek (struct nl_handle *handle) |
Enable use of MSG_PEEK when reading from socket. | |
void | nl_socket_disable_msg_peek (struct nl_handle *handle) |
Disable use of MSG_PEEK when reading from socket. | |
Callback Handler | |
struct nl_cb * | nl_socket_get_cb (struct nl_handle *handle) |
void | nl_socket_set_cb (struct nl_handle *handle, struct nl_cb *cb) |
int | nl_socket_modify_cb (struct nl_handle *handle, enum nl_cb_type type, enum nl_cb_kind kind, nl_recvmsg_msg_cb_t func, void *arg) |
Modify the callback handler associated to the socket. | |
Utilities | |
int | nl_set_buffer_size (struct nl_handle *handle, int rxbuf, int txbuf) |
Set socket buffer size of netlink handle. | |
int | nl_set_passcred (struct nl_handle *handle, int state) |
Enable/disable credential passing on netlink handle. | |
int | nl_socket_recv_pktinfo (struct nl_handle *handle, int state) |
Enable/disable receival of additional packet information. |
The socket is represented in a structure called the netlink handle, besides the socket, it stores various settings and values related to the socket. Every socket handle has a mandatory association with a set of callbacks which can be used to modify the behaviour when sending/receiving data from the socket.
struct nl_handle *handle; // Allocate and initialize a new netlink handle handle = nl_handle_alloc(); // Use nl_socket_get_fd() to fetch the file description, for example to // put a socket into non-blocking i/o mode. fcntl(nl_socket_get_fd(handle), F_SETFL, O_NONBLOCK);
// Event notifications are typically sent to multicast addresses which // represented by groups. Join a group to f.e. receive link notifications. nl_socket_add_membership(handle, RTNLGRP_LINK);
// Finally destroy the netlink handle nl_handle_destroy(handle);
struct nl_handle* nl_handle_alloc | ( | void | ) | [read] |
Definition at line 206 of file socket.c.
References nl_cb_alloc().
{ struct nl_cb *cb; cb = nl_cb_alloc(default_cb); if (!cb) { nl_errno(ENOMEM); return NULL; } return __alloc_handle(cb); }
struct nl_handle* nl_handle_alloc_cb | ( | struct nl_cb * | cb | ) | [read] |
cb | Callback handler |
The reference to the callback handler is taken into account automatically, it is released again upon calling nl_handle_destroy().
Definition at line 228 of file socket.c.
{ if (cb == NULL) BUG(); return __alloc_handle(nl_cb_get(cb)); }
void nl_handle_destroy | ( | struct nl_handle * | handle | ) |
handle | Netlink handle. |
Definition at line 240 of file socket.c.
Referenced by nl_cache_mngr_free().
{ if (!handle) return; if (handle->h_fd >= 0) close(handle->h_fd); if (!(handle->h_flags & NL_OWN_PORT)) release_local_port(handle->h_local.nl_pid); nl_cb_put(handle->h_cb); free(handle); }
void nl_disable_sequence_check | ( | struct nl_handle * | handle | ) |
handle | Netlink handle. |
Disables checking of sequence numbers on the netlink handle. This is required to allow messages to be processed which were not requested by a preceding request message, e.g. netlink events.
Definition at line 279 of file socket.c.
References NL_CB_CUSTOM, NL_CB_SEQ_CHECK, and nl_cb_set().
Referenced by nl_cache_mngr_alloc().
{ nl_cb_set(handle->h_cb, NL_CB_SEQ_CHECK, NL_CB_CUSTOM, noop_seq_check, NULL); }
unsigned int nl_socket_use_seq | ( | struct nl_handle * | handle | ) |
void nl_socket_set_local_port | ( | struct nl_handle * | handle, |
uint32_t | port | ||
) |
handle | Netlink handle |
port | Local port identifier |
Assigns a local port identifier to the socket. If port is 0 a unique port identifier will be generated automatically.
Definition at line 319 of file socket.c.
{ if (port == 0) { port = generate_local_port(); handle->h_flags &= ~NL_OWN_PORT; } else { if (!(handle->h_flags & NL_OWN_PORT)) release_local_port(handle->h_local.nl_pid); handle->h_flags |= NL_OWN_PORT; } handle->h_local.nl_pid = port; }
int nl_socket_add_membership | ( | struct nl_handle * | handle, |
int | group | ||
) |
handle | Netlink handle |
group | Group identifier |
Joins the specified group 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.
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.
Definition at line 355 of file socket.c.
Referenced by nl_cache_mngr_add().
{ int err; if (handle->h_fd == -1) return nl_error(EBADFD, "Socket not connected"); err = setsockopt(handle->h_fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP, &group, sizeof(group)); if (err < 0) return nl_error(errno, "setsockopt(NETLINK_ADD_MEMBERSHIP) " "failed"); return 0; }
int nl_socket_drop_membership | ( | struct nl_handle * | handle, |
int | group | ||
) |
handle | Netlink handle |
group | Group identifier |
Leaves the specified group using the modern socket option which is available since kernel version 2.6.14.
Definition at line 382 of file socket.c.
Referenced by nl_cache_mngr_add().
{ int err; if (handle->h_fd == -1) return nl_error(EBADFD, "Socket not connected"); err = setsockopt(handle->h_fd, SOL_NETLINK, NETLINK_DROP_MEMBERSHIP, &group, sizeof(group)); if (err < 0) return nl_error(errno, "setsockopt(NETLINK_DROP_MEMBERSHIP) " "failed"); return 0; }
void nl_join_groups | ( | struct nl_handle * | handle, |
int | groups | ||
) |
handle | Netlink handle. |
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 407 of file socket.c.
{ handle->h_local.nl_groups |= groups; }
int nl_socket_set_nonblocking | ( | struct nl_handle * | handle | ) |
handle | Netlink socket |
Definition at line 448 of file socket.c.
Referenced by nl_cache_mngr_alloc().
{ if (handle->h_fd == -1) return nl_error(EBADFD, "Socket not connected"); if (fcntl(handle->h_fd, F_SETFL, O_NONBLOCK) < 0) return nl_error(errno, "fcntl(F_SETFL, O_NONBLOCK) failed"); return 0; }
void nl_socket_enable_msg_peek | ( | struct nl_handle * | handle | ) |
void nl_socket_disable_msg_peek | ( | struct nl_handle * | handle | ) |
int nl_socket_modify_cb | ( | struct nl_handle * | handle, |
enum nl_cb_type | type, | ||
enum nl_cb_kind | kind, | ||
nl_recvmsg_msg_cb_t | func, | ||
void * | arg | ||
) |
handle | netlink handle |
type | which type callback to set |
kind | kind of callback |
func | callback function |
arg | argument to be passwd to callback function |
Definition at line 505 of file socket.c.
References nl_cb_set().
Referenced by nl_cache_mngr_alloc().
{ return nl_cb_set(handle->h_cb, type, kind, func, arg); }
int nl_set_buffer_size | ( | struct nl_handle * | handle, |
int | rxbuf, | ||
int | txbuf | ||
) |
handle | Netlink handle. |
rxbuf | New receive socket buffer size in bytes. |
txbuf | New transmit socket buffer size in bytes. |
Sets the socket buffer size of a netlink handle to the specified values rxbuf
and txbuf
. Providing a value of 0
assumes a good default value.
Definition at line 532 of file socket.c.
Referenced by nl_connect().
{ int err; if (rxbuf <= 0) rxbuf = 32768; if (txbuf <= 0) txbuf = 32768; if (handle->h_fd == -1) return nl_error(EBADFD, "Socket not connected"); err = setsockopt(handle->h_fd, SOL_SOCKET, SO_SNDBUF, &txbuf, sizeof(txbuf)); if (err < 0) return nl_error(errno, "setsockopt(SO_SNDBUF) failed"); err = setsockopt(handle->h_fd, SOL_SOCKET, SO_RCVBUF, &rxbuf, sizeof(rxbuf)); if (err < 0) return nl_error(errno, "setsockopt(SO_RCVBUF) failed"); handle->h_flags |= NL_SOCK_BUFSIZE_SET; return 0; }
int nl_set_passcred | ( | struct nl_handle * | handle, |
int | state | ||
) |
handle | Netlink handle |
state | New state (0 - disabled, 1 - enabled) |
Definition at line 567 of file socket.c.
{ int err; if (handle->h_fd == -1) return nl_error(EBADFD, "Socket not connected"); err = setsockopt(handle->h_fd, SOL_SOCKET, SO_PASSCRED, &state, sizeof(state)); if (err < 0) return nl_error(errno, "setsockopt(SO_PASSCRED) failed"); if (state) handle->h_flags |= NL_SOCK_PASSCRED; else handle->h_flags &= ~NL_SOCK_PASSCRED; return 0; }
int nl_socket_recv_pktinfo | ( | struct nl_handle * | handle, |
int | state | ||
) |
handle | Netlink handle |
state | New state (0 - disabled, 1 - enabled) |
Definition at line 594 of file socket.c.
{ int err; if (handle->h_fd == -1) return nl_error(EBADFD, "Socket not connected"); err = setsockopt(handle->h_fd, SOL_NETLINK, NETLINK_PKTINFO, &state, sizeof(state)); if (err < 0) return nl_error(errno, "setsockopt(NETLINK_PKTINFO) failed"); return 0; }