/*
* 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) 2003-2012 Thomas Graf <tgraf@suug.ch>
*/
/**
* @ingroup core_types
* @defgroup socket Socket
*
* Representation of a netlink socket
*
* Related sections in the development guide:
* - @core_doc{core_sockets, Netlink Sockets}
*
* @{
*
* Header
* ------
* ~~~~{.c}
* #include <netlink/socket.h>
* ~~~~
*/
#include "defs.h"
#include <netlink-private/netlink.h>
#include <netlink-private/socket.h>
#include <netlink/netlink.h>
#include <netlink/utils.h>
#include <netlink/handlers.h>
#include <netlink/msg.h>
#include <netlink/attr.h>
static int default_cb = NL_CB_DEFAULT;
static void __init init_default_cb(void)
{
char *nlcb;
if ((nlcb = getenv("NLCB"))) {
if (!strcasecmp(nlcb, "default"))
default_cb = NL_CB_DEFAULT;
else if (!strcasecmp(nlcb, "verbose"))
default_cb = NL_CB_VERBOSE;
else if (!strcasecmp(nlcb, "debug"))
default_cb = NL_CB_DEBUG;
else {
fprintf(stderr, "Unknown value for NLCB, valid values: "
"{default | verbose | debug}\n");
}
}
}
static uint32_t used_ports_map[32];
static NL_RW_LOCK(port_map_lock);
static uint32_t generate_local_port(void)
{
int i, j, n, m;
static uint16_t idx_state = 0;
uint32_t pid = getpid() & 0x3FFFFF;
nl_write_lock(&port_map_lock);
if (idx_state == 0) {
uint32_t t = time(NULL);
/* from time to time (on average each 2^15 calls), the idx_state will
* be zero again. No problem, just "seed" anew with time(). */
idx_state = t ^ (t >> 16) ^ 0x3047;
} else
idx_state = idx_state + 20011; /* add prime number */
i = idx_state >> 5;
n = idx_state;
for (j = 0; j < 32; j++) {
/* walk the index somewhat randomized, with always leaving the block
* #0 as last. The reason is that libnl-1 will start at block #0,
* so just leave the first 32 ports preferably for libnl-1 owned sockets
* (this is relevant only if the applications ends up using both versions
* of the library and doesn't hurt otherwise). */
if (j == 31)
i = 0;
else
i = (((i-1) + 7) % 31) + 1;
if (used_ports_map[i] == 0xFFFFFFFF)
continue;
for (m = 0; m < 32; m++) {
n = (n + 13) % 32;
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. */
nl_write_unlock(&port_map_lock);
return pid + (((uint32_t)n) << 22);
}
}
nl_write_unlock(&port_map_lock);
/* Out of sockets in our own PID namespace, what to do? FIXME */
NL_DBG(1, "Warning: Ran out of unique local port namespace\n");
return UINT32_MAX;
}
static void release_local_port(uint32_t port)
{
int nr;
uint32_t mask;
if (port == UINT32_MAX)
return;
BUG_ON(port == 0);
nr = port >> 22;
mask = 1UL << (nr % 32);
nr /= 32;
nl_write_lock(&port_map_lock);
BUG_ON((used_ports_map[nr] & mask) != mask);
used_ports_map[nr] &= ~mask;
nl_write_unlock(&port_map_lock);
}
/** \cond skip */
void _nl_socket_used_ports_release_all(const uint32_t *used_ports)
{
int i;
for (i = 0; i < 32; i++) {
if (used_ports[i] != 0) {
nl_write_lock(&port_map_lock);
for (; i < 32; i++) {
BUG_ON((used_ports_map[i] & used_ports[i]) != used_ports[i]);
used_ports_map[i] &= ~(used_ports[i]);
}
nl_write_unlock(&port_map_lock);
return;
}
}
}
void _nl_socket_used_ports_set(uint32_t *used_ports, uint32_t port)
{
int nr;
int32_t mask;
nr = port >> 22;
mask = 1UL << (nr % 32);
nr /= 32;
/*
BUG_ON(port == UINT32_MAX || port == 0 || (getpid() & 0x3FFFFF) != (port & 0x3FFFFF));
BUG_ON(used_ports[nr] & mask);
*/
used_ports[nr] |= mask;
}
/** \endcond */
/**
* @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 = nl_cb_get(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);
/* the port is 0 (unspecified), meaning NL_OWN_PORT */
sk->s_flags = NL_OWN_PORT;
return sk;
}
/**
* Allocate new netlink socket
*
* @return Newly allocated netlink socket or NULL.
*/
struct nl_sock *nl_socket_alloc(void)
{
struct nl_cb *cb;
struct nl_sock *sk;
cb = nl_cb_alloc(default_cb);
if (!cb)
return NULL;
/* will increment cb reference count on success */
sk = __alloc_socket(cb);
nl_cb_put(cb);
return sk;
}
/**
* 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(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);
}
/**
* Use next sequence number
* @arg sk Netlink socket.
*
* Uses the next available sequence number and increases the counter
* by one for subsequent calls.
*
* @return Unique serial sequence number
*/
unsigned int nl_socket_use_seq(struct nl_sock *sk)
{
return sk->s_seq_next++;
}
/**
* Disable automatic request for ACK
* @arg 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.
*/
void nl_socket_disable_auto_ack(struct nl_sock *sk)
{
sk->s_flags |= NL_NO_AUTO_ACK;
}
/**
* Enable automatic request for ACK (default)
* @arg sk Netlink socket.
* @see nl_socket_disable_auto_ack
*/
void nl_socket_enable_auto_ack(struct nl_sock *sk)
{
sk->s_flags &= ~NL_NO_AUTO_ACK;
}
/** @} */
/** \cond skip */
int _nl_socket_is_local_port_unspecified(struct nl_sock *sk)
{
return (sk->s_local.nl_pid == 0);
}
uint32_t _nl_socket_generate_local_port_no_release(struct nl_sock *sk)
{
uint32_t port;
/* reset the port to generate_local_port(), but do not release
* the previously generated port. */
port = generate_local_port();
sk->s_flags &= ~NL_OWN_PORT;
sk->s_local.nl_pid = port;
return port;
}
/** \endcond */
/**
* @name Source Idenficiation
* @{
*/
uint32_t nl_socket_get_local_port(const struct nl_sock *sk)
{
if (sk->s_local.nl_pid == 0) {
/* modify the const argument sk. This is justified, because
* nobody ever saw the local_port from externally. So, we
* initilize it on first use.
*
* Note that this also means that you cannot call this function
* from multiple threads without synchronization. But nl_sock
* is not automatically threadsafe anyway, so the user is not
* allowed to do that.
*/
return _nl_socket_generate_local_port_no_release((struct nl_sock *) sk);
}
return sk->s_local.nl_pid;
}
/**
* 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, 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()).
*/
void nl_socket_set_local_port(struct nl_sock *sk, uint32_t port)
{
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) {
va_end(ap);
return -NLE_INVAL;
}
err = setsockopt(sk->s_fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP,
&group, sizeof(group));
if (err < 0) {
va_end(ap);
return -nl_syserr2nlerr(errno);
}
group = va_arg(ap, int);
}
va_end(ap);
return 0;
}
int nl_socket_add_membership(struct nl_sock *sk, int group)
{
return nl_socket_add_memberships(sk, group, 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) {
va_end(ap);
return -NLE_INVAL;
}
err = setsockopt(sk->s_fd, SOL_NETLINK, NETLINK_DROP_MEMBERSHIP,
&group, sizeof(group));
if (err < 0) {
va_end(ap);
return -nl_syserr2nlerr(errno);
}
group = va_arg(ap, int);
}
va_end(ap);
return 0;
}
int nl_socket_drop_membership(struct nl_sock *sk, int group)
{
return nl_socket_drop_memberships(sk, group, 0);
}
/**
* Join multicast groups (deprecated)
* @arg sk Netlink socket.
* @arg 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.
*/
void nl_join_groups(struct nl_sock *sk, int groups)
{
sk->s_local.nl_groups |= groups;
}
/** @} */
/**
* @name Peer Identfication
* @{
*/
uint32_t nl_socket_get_peer_port(const struct nl_sock *sk)
{
return sk->s_peer.nl_pid;
}
void nl_socket_set_peer_port(struct nl_sock *sk, uint32_t port)
{
sk->s_peer.nl_pid = port;
}
uint32_t nl_socket_get_peer_groups(const struct nl_sock *sk)
{
return sk->s_peer.nl_groups;
}
void nl_socket_set_peer_groups(struct nl_sock *sk, uint32_t groups)
{
sk->s_peer.nl_groups = groups;
}
/** @} */
/**
* @name File Descriptor
* @{
*/
/**
* Return the file descriptor of the backing socket
* @arg sk Netlink socket
*
* Only valid after calling nl_connect() to create and bind the respective
* socket.
*
* @return File descriptor or -1 if not available.
*/
int nl_socket_get_fd(const struct nl_sock *sk)
{
return sk->s_fd;
}
/**
* 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(const 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;
}
/**
* Enable use of MSG_PEEK when reading from socket
* @arg sk Netlink socket.
*/
void nl_socket_enable_msg_peek(struct nl_sock *sk)
{
sk->s_flags |= NL_MSG_PEEK;
}
/**
* Disable use of MSG_PEEK when reading from socket
* @arg sk Netlink socket.
*/
void nl_socket_disable_msg_peek(struct nl_sock *sk)
{
sk->s_flags &= ~NL_MSG_PEEK;
}
/** @} */
/**
* @name Callback Handler
* @{
*/
struct nl_cb *nl_socket_get_cb(const struct nl_sock *sk)
{
return nl_cb_get(sk->s_cb);
}
void nl_socket_set_cb(struct nl_sock *sk, struct nl_cb *cb)
{
if (cb == NULL)
BUG();
nl_cb_put(sk->s_cb);
sk->s_cb = nl_cb_get(cb);
}
/**
* Modify the callback handler associated with the socket
* @arg sk Netlink socket.
* @arg type which type callback to set
* @arg kind kind of callback
* @arg func callback function
* @arg arg argument to be passed to callback function
*
* @see nl_cb_set
*/
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)
{
return nl_cb_set(sk->s_cb, type, kind, func, arg);
}
/**
* Modify the error callback handler associated with the socket
* @arg sk Netlink socket.
* @arg kind kind of callback
* @arg func callback function
* @arg arg argument to be passed to callback function
*
* @see nl_cb_err
*/
int nl_socket_modify_err_cb(struct nl_sock *sk, enum nl_cb_kind kind,
nl_recvmsg_err_cb_t func, void *arg)
{
return nl_cb_err(sk->s_cb, kind, func, arg);
}
/** @} */
/**
* @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;
}
/**
* Set default message buffer size of netlink socket.
* @arg sk Netlink socket.
* @arg 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.
*
* @return 0 on success or a negative error code.
*/
int nl_socket_set_msg_buf_size(struct nl_sock *sk, size_t bufsize)
{
sk->s_bufsize = bufsize;
return 0;
}
/**
* Get default message buffer size of netlink socket.
* @arg sk Netlink socket.
*
* @return Size of default message buffer.
*/
size_t nl_socket_get_msg_buf_size(struct nl_sock *sk)
{
return sk->s_bufsize;
}
/**
* 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;
}
/** @} */
/** @} */