OpenWrt – Rev 1
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/*
* lib/socket.c Netlink Socket
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation version 2.1
* of the License.
*
* Copyright (c) 2003-2008 Thomas Graf <tgraf@suug.ch>
*/
/**
* @ingroup core
* @defgroup socket Socket
* @{
*/
#include <netlink-local.h>
#include <netlink/netlink.h>
#include <netlink/utils.h>
#include <netlink/handlers.h>
#include <netlink/msg.h>
#include <netlink/attr.h>
static uint32_t used_ports_map[32];
static uint32_t generate_local_port(void)
{
int i, n;
uint32_t pid = getpid() & 0x3FFFFF;
for (i = 0; i < 32; i++) {
if (used_ports_map[i] == 0xFFFFFFFF)
continue;
for (n = 0; n < 32; n++) {
if (1UL & (used_ports_map[i] >> n))
continue;
used_ports_map[i] |= (1UL << n);
n += (i * 32);
/* PID_MAX_LIMIT is currently at 2^22, leaving 10 bit
* to, i.e. 1024 unique ports per application. */
return pid + (n << 22);
}
}
/* Out of sockets in our own PID namespace, what to do? FIXME */
return UINT_MAX;
}
static void release_local_port(uint32_t port)
{
int nr;
if (port == UINT_MAX)
return;
nr = port >> 22;
used_ports_map[nr / 32] &= ~(1 << nr % 32);
}
/**
* @name Allocation
* @{
*/
static struct nl_sock *__alloc_socket(struct nl_cb *cb)
{
struct nl_sock *sk;
sk = calloc(1, sizeof(*sk));
if (!sk)
return NULL;
sk->s_fd = -1;
sk->s_cb = cb;
sk->s_local.nl_family = AF_NETLINK;
sk->s_peer.nl_family = AF_NETLINK;
sk->s_seq_expect = sk->s_seq_next = time(0);
sk->s_local.nl_pid = generate_local_port();
if (sk->s_local.nl_pid == UINT_MAX) {
nl_socket_free(sk);
return NULL;
}
return sk;
}
/**
* Allocate new netlink socket
*
* @return Newly allocated netlink socket or NULL.
*/
struct nl_sock *nl_socket_alloc(void)
{
struct nl_cb *cb;
cb = nl_cb_alloc(NL_CB_DEFAULT);
if (!cb)
return NULL;
return __alloc_socket(cb);
}
/**
* Allocate new socket with custom callbacks
* @arg cb Callback handler
*
* The reference to the callback handler is taken into account
* automatically, it is released again upon calling nl_socket_free().
*
*@return Newly allocted socket handle or NULL.
*/
struct nl_sock *nl_socket_alloc_cb(struct nl_cb *cb)
{
if (cb == NULL)
BUG();
return __alloc_socket(nl_cb_get(cb));
}
/**
* Free a netlink socket.
* @arg sk Netlink socket.
*/
void nl_socket_free(struct nl_sock *sk)
{
if (!sk)
return;
if (sk->s_fd >= 0)
close(sk->s_fd);
if (!(sk->s_flags & NL_OWN_PORT))
release_local_port(sk->s_local.nl_pid);
nl_cb_put(sk->s_cb);
free(sk);
}
/** @} */
/**
* @name Sequence Numbers
* @{
*/
static int noop_seq_check(struct nl_msg *msg, void *arg)
{
return NL_OK;
}
/**
* Disable sequence number checking.
* @arg 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.
*/
void nl_socket_disable_seq_check(struct nl_sock *sk)
{
nl_cb_set(sk->s_cb, NL_CB_SEQ_CHECK,
NL_CB_CUSTOM, noop_seq_check, NULL);
}
/** @} */
/**
* Set local port of socket
* @arg sk Netlink socket.
* @arg port Local port identifier
*
* Assigns a local port identifier to the socket. If port is 0
* a unique port identifier will be generated automatically.
*/
void nl_socket_set_local_port(struct nl_sock *sk, uint32_t port)
{
if (port == 0) {
port = generate_local_port();
sk->s_flags &= ~NL_OWN_PORT;
} else {
if (!(sk->s_flags & NL_OWN_PORT))
release_local_port(sk->s_local.nl_pid);
sk->s_flags |= NL_OWN_PORT;
}
sk->s_local.nl_pid = port;
}
/** @} */
/**
* @name Group Subscriptions
* @{
*/
/**
* Join groups
* @arg sk Netlink socket
* @arg 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.
*
* @return 0 on sucess or a negative error code.
*/
int nl_socket_add_memberships(struct nl_sock *sk, int group, ...)
{
int err;
va_list ap;
if (sk->s_fd == -1)
return -NLE_BAD_SOCK;
va_start(ap, group);
while (group != 0) {
if (group < 0)
return -NLE_INVAL;
err = setsockopt(sk->s_fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP,
&group, sizeof(group));
if (err < 0)
return -nl_syserr2nlerr(errno);
group = va_arg(ap, int);
}
va_end(ap);
return 0;
}
/**
* Leave groups
* @arg sk Netlink socket
* @arg 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 nl_socket_add_membership
* @return 0 on success or a negative error code.
*/
int nl_socket_drop_memberships(struct nl_sock *sk, int group, ...)
{
int err;
va_list ap;
if (sk->s_fd == -1)
return -NLE_BAD_SOCK;
va_start(ap, group);
while (group != 0) {
if (group < 0)
return -NLE_INVAL;
err = setsockopt(sk->s_fd, SOL_NETLINK, NETLINK_DROP_MEMBERSHIP,
&group, sizeof(group));
if (err < 0)
return -nl_syserr2nlerr(errno);
group = va_arg(ap, int);
}
va_end(ap);
return 0;
}
/** @} */
/**
* Set file descriptor of socket to non-blocking state
* @arg sk Netlink socket.
*
* @return 0 on success or a negative error code.
*/
int nl_socket_set_nonblocking(struct nl_sock *sk)
{
if (sk->s_fd == -1)
return -NLE_BAD_SOCK;
if (fcntl(sk->s_fd, F_SETFL, O_NONBLOCK) < 0)
return -nl_syserr2nlerr(errno);
return 0;
}
/** @} */
/**
* @name Utilities
* @{
*/
/**
* Set socket buffer size of netlink socket.
* @arg sk Netlink socket.
* @arg rxbuf New receive socket buffer size in bytes.
* @arg txbuf New transmit socket buffer size in bytes.
*
* Sets the socket buffer size of a netlink socket to the specified
* values \c rxbuf and \c txbuf. Providing a value of \c 0 assumes a
* good default value.
*
* @note It is not required to call this function prior to nl_connect().
* @return 0 on sucess or a negative error code.
*/
int nl_socket_set_buffer_size(struct nl_sock *sk, int rxbuf, int txbuf)
{
int err;
if (rxbuf <= 0)
rxbuf = 32768;
if (txbuf <= 0)
txbuf = 32768;
if (sk->s_fd == -1)
return -NLE_BAD_SOCK;
err = setsockopt(sk->s_fd, SOL_SOCKET, SO_SNDBUF,
&txbuf, sizeof(txbuf));
if (err < 0)
return -nl_syserr2nlerr(errno);
err = setsockopt(sk->s_fd, SOL_SOCKET, SO_RCVBUF,
&rxbuf, sizeof(rxbuf));
if (err < 0)
return -nl_syserr2nlerr(errno);
sk->s_flags |= NL_SOCK_BUFSIZE_SET;
return 0;
}
/**
* Enable/disable credential passing on netlink socket.
* @arg sk Netlink socket.
* @arg state New state (0 - disabled, 1 - enabled)
*
* @return 0 on success or a negative error code
*/
int nl_socket_set_passcred(struct nl_sock *sk, int state)
{
int err;
if (sk->s_fd == -1)
return -NLE_BAD_SOCK;
err = setsockopt(sk->s_fd, SOL_SOCKET, SO_PASSCRED,
&state, sizeof(state));
if (err < 0)
return -nl_syserr2nlerr(errno);
if (state)
sk->s_flags |= NL_SOCK_PASSCRED;
else
sk->s_flags &= ~NL_SOCK_PASSCRED;
return 0;
}
/**
* Enable/disable receival of additional packet information
* @arg sk Netlink socket.
* @arg state New state (0 - disabled, 1 - enabled)
*
* @return 0 on success or a negative error code
*/
int nl_socket_recv_pktinfo(struct nl_sock *sk, int state)
{
int err;
if (sk->s_fd == -1)
return -NLE_BAD_SOCK;
err = setsockopt(sk->s_fd, SOL_NETLINK, NETLINK_PKTINFO,
&state, sizeof(state));
if (err < 0)
return -nl_syserr2nlerr(errno);
return 0;
}
/** @} */
/** @} */