2  * (C) 2008-2010 by Pablo Neira Ayuso <pablo@netfilter.org>
11 #include <sys/socket.h>
22  * libmnl is a minimalistic user-space library oriented to Netlink developers.
26  * re-inventing the wheel in common Netlink tasks.
29 "Simplify, simplify" -- Henry David Thoureau. Walden (1854)
38  * - Small: the shared library requires around 30KB for an x86-based computer.
39  * - Simple: this library avoids complex abstractions that tend to hide Netlink
40  *   details. It avoids elaborated object-oriented infrastructure and complex
41  *   callback-based workflow.
42  * - Easy to use: the library simplifies the work for Netlink-wise developers.
43  *   It provides functions to make socket handling, message building,
45  * - Easy to re-use: you can use this library to build your own abstraction
48  * - Decoupling: the interdependency of the main bricks that compose this
62  * http://git.netfilter.org/cgi-bin/gitweb.cgi?p=libmnl.git;a=summary
75  * \defgroup socket Netlink socket helpers
80  * mnl_socket_get_fd - obtain file descriptor from netlink socket
81  * \param nl netlink socket obtained via mnl_socket_open()
83  * This function returns the file descriptor of a given netlink socket.
87 	return nl->fd;  in mnl_socket_get_fd()
91  * mnl_socket_get_portid - obtain Netlink PortID from netlink socket
92  * \param nl netlink socket obtained via mnl_socket_open()
94  * This function returns the Netlink PortID of a given netlink socket.
97  * socket that is binded to the same Netlink subsystem from the same process.
101 	return nl->addr.nl_pid;  in mnl_socket_get_portid()
112 	nl->fd = socket(AF_NETLINK, SOCK_RAW | flags, bus);  in __mnl_socket_open()
113 	if (nl->fd == -1) {  in __mnl_socket_open()
122  * mnl_socket_open - open a netlink socket
123  * \param bus the netlink socket bus ID (see NETLINK_* constants)
134  * mnl_socket_open2 - open a netlink socket with appropriate flags
135  * \param bus the netlink socket bus ID (see NETLINK_* constants)
136  * \param flags the netlink socket flags (see SOCK_* constants in socket(2))
139  * SOCK_CLOEXEC at socket creation time (useful for multi-threaded programs
151  * mnl_socket_fdopen - associates a mnl_socket object with pre-existing socket.
152  * \param fd pre-existing socket descriptor.
156  * if the socket fd is already bound and it is AF_NETLINK.
159  * non-netlink socket.
169 	if (ret == -1)  in mnl_socket_fdopen()
176 	nl->fd = fd;  in mnl_socket_fdopen()
178 		nl->addr = addr;  in mnl_socket_fdopen()
184  * mnl_socket_bind - bind netlink socket
185  * \param nl netlink socket obtained via mnl_socket_open()
189  * On error, this function returns -1 and errno is appropriately set. On
199 	nl->addr.nl_family = AF_NETLINK;  in mnl_socket_bind()
200 	nl->addr.nl_groups = groups;  in mnl_socket_bind()
201 	nl->addr.nl_pid = pid;  in mnl_socket_bind()
203 	ret = bind(nl->fd, (struct sockaddr *) &nl->addr, sizeof (nl->addr));  in mnl_socket_bind()
207 	addr_len = sizeof(nl->addr);  in mnl_socket_bind()
208 	ret = getsockname(nl->fd, (struct sockaddr *) &nl->addr, &addr_len);  in mnl_socket_bind()
212 	if (addr_len != sizeof(nl->addr)) {  in mnl_socket_bind()
214 		return -1;  in mnl_socket_bind()
216 	if (nl->addr.nl_family != AF_NETLINK) {  in mnl_socket_bind()
218 		return -1;  in mnl_socket_bind()
224  * mnl_socket_sendto - send a netlink message of a certain size
225  * \param nl netlink socket obtained via mnl_socket_open()
229  * On error, it returns -1 and errno is appropriately set. Otherwise, it 
238 	return sendto(nl->fd, buf, len, 0,   in mnl_socket_sendto()
243  * mnl_socket_recvfrom - receive a netlink message
244  * \param nl netlink socket obtained via mnl_socket_open()
248  * On error, it returns -1 and errno is appropriately set. If errno is set
274 	ret = recvmsg(nl->fd, &msg, 0);  in mnl_socket_recvfrom()
275 	if (ret == -1)  in mnl_socket_recvfrom()
280 		return -1;  in mnl_socket_recvfrom()
284 		return -1;  in mnl_socket_recvfrom()
290  * mnl_socket_close - close a given netlink socket
291  * \param nl netlink socket obtained via mnl_socket_open()
293  * On error, this function returns -1 and errno is appropriately set.
298 	int ret = close(nl->fd);  in mnl_socket_close()
304  * mnl_socket_setsockopt - set Netlink socket option
305  * \param nl netlink socket obtained via mnl_socket_open()
306  * \param type type of Netlink socket options
310  * This function allows you to set some Netlink socket option. As of writing
313  *	- \#define NETLINK_ADD_MEMBERSHIP  1
314  *	- \#define NETLINK_DROP_MEMBERSHIP 2
315  *	- \#define NETLINK_PKTINFO         3
316  *	- \#define NETLINK_BROADCAST_ERROR 4
317  *	- \#define NETLINK_NO_ENOBUFS      5
320  * 32-bits mask. However, since 2.6.14, Netlink may have up to 2^32 multicast
324  * and the 32-bit mask to join a set of Netlink multicast groups.
326  * On error, this function returns -1 and errno is appropriately set.
331 	return setsockopt(nl->fd, SOL_NETLINK, type, buf, len);  in mnl_socket_setsockopt()
335  * mnl_socket_getsockopt - get a Netlink socket option
336  * \param nl netlink socket obtained via mnl_socket_open()
337  * \param type type of Netlink socket options
341  * On error, this function returns -1 and errno is appropriately set.
346 	return getsockopt(nl->fd, SOL_NETLINK, type, buf, len);  in mnl_socket_getsockopt()