2 * lib/cache_mngr.c Cache Manager
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser General Public
6 * License as published by the Free Software Foundation version 2.1
9 * Copyright (c) 2003-2007 Thomas Graf <tgraf@suug.ch>
14 * @defgroup cache_mngr Manager
15 * @brief Helps keeping caches up to date.
17 * The purpose of a cache manager is to keep track of caches and
18 * automatically receive event notifications to keep the caches
19 * up to date with the kernel state. Each manager has exactly one
20 * netlink socket assigned which limits the scope of each manager
21 * to exactly one netlink family. Therefore all caches committed
22 * to a manager must be part of the same netlink family. Due to the
23 * nature of a manager, it is not possible to have a cache maintain
24 * two instances of the same cache type. The socket is subscribed
25 * to the event notification group of each cache and also put into
26 * non-blocking mode. Functions exist to poll() on the socket to
27 * wait for new events to be received.
32 * +-----------------+ [ notification, link change ]
33 * | | Cache Manager | | [ (IFF_UP | IFF_RUNNING) ]
35 * | | +------------+| | | [ notification, new addr ]
36 * <-------|---| route/link |<-------(async)--+ [ 10.0.1.1/32 dev eth1 ]
37 * | | +------------+| | |
39 * <---|---|---| route/addr |<------|-(async)--------------+
41 * | | +------------+| |
42 * <-------|---| ... ||
43 * | | +------------+| |
48 * @par 1) Creating a new cache manager
50 * struct nl_cache_mngr *mngr;
52 * // Allocate a new cache manager for RTNETLINK and automatically
53 * // provide the caches added to the manager.
54 * mngr = nl_cache_mngr_alloc(NETLINK_ROUTE, NL_AUTO_PROVIDE);
57 * @par 2) Keep track of a cache
59 * struct nl_cache *cache;
61 * // Create a new cache for links/interfaces and ask the manager to
62 * // keep it up to date for us. This will trigger a full dump request
63 * // to initially fill the cache.
64 * cache = nl_cache_mngr_add(mngr, "route/link");
67 * @par 3) Make the manager receive updates
69 * // Give the manager the ability to receive updates, will call poll()
70 * // with a timeout of 5 seconds.
71 * if (nl_cache_mngr_poll(mngr, 5000) > 0) {
72 * // Manager received at least one update, dump cache?
73 * nl_cache_dump(cache, ...);
77 * @par 4) Release cache manager
79 * nl_cache_mngr_free(mngr);
84 #include <netlink-local.h>
85 #include <netlink/netlink.h>
86 #include <netlink/cache.h>
87 #include <netlink/utils.h>
89 static int include_cb(struct nl_object *obj, struct nl_parser_param *p)
91 struct nl_cache_assoc *ca = p->pp_arg;
93 NL_DBG(2, "Including object %p into cache %p\n", obj, ca->ca_cache);
96 nl_object_dump(obj, &nl_debug_dp);
98 return nl_cache_include(ca->ca_cache, obj, ca->ca_change);
101 static int event_input(struct nl_msg *msg, void *arg)
103 struct nl_cache_mngr *mngr = arg;
104 int protocol = nlmsg_get_proto(msg);
105 int type = nlmsg_hdr(msg)->nlmsg_type;
106 struct nl_cache_ops *ops;
108 struct nl_parser_param p = {
112 NL_DBG(2, "Cache manager %p, handling new message %p as event\n",
116 nl_msg_dump(msg, stderr);
119 if (mngr->cm_protocol != protocol)
122 for (i = 0; i < mngr->cm_nassocs; i++) {
123 if (mngr->cm_assocs[i].ca_cache) {
124 ops = mngr->cm_assocs[i].ca_cache->c_ops;
125 for (n = 0; ops->co_msgtypes[n].mt_id >= 0; n++)
126 if (ops->co_msgtypes[n].mt_id == type)
134 NL_DBG(2, "Associated message %p to cache %p\n",
135 msg, mngr->cm_assocs[i].ca_cache);
136 p.pp_arg = &mngr->cm_assocs[i];
138 return nl_cache_parse(ops, NULL, nlmsg_hdr(msg), &p);
142 * Allocate new cache manager
143 * @arg handle Netlink socket/handle to be used
144 * @arg protocol Netlink Protocol this manager is used for
147 * @return Newly allocated cache manager or NULL on failure.
149 struct nl_cache_mngr *nl_cache_mngr_alloc(struct nl_handle *handle,
150 int protocol, int flags)
152 struct nl_cache_mngr *mngr;
157 mngr = calloc(1, sizeof(*mngr));
161 mngr->cm_handle = handle;
162 mngr->cm_nassocs = 32;
163 mngr->cm_protocol = protocol;
164 mngr->cm_flags = flags;
165 mngr->cm_assocs = calloc(mngr->cm_nassocs,
166 sizeof(struct nl_cache_assoc));
167 if (!mngr->cm_assocs)
171 nl_socket_modify_cb(mngr->cm_handle, NL_CB_VALID, NL_CB_CUSTOM,
174 /* Required to receive async event notifications */
175 nl_disable_sequence_check(mngr->cm_handle);
177 if (nl_connect(mngr->cm_handle, protocol) < 0)
180 if (nl_socket_set_nonblocking(mngr->cm_handle) < 0)
183 NL_DBG(1, "Allocated cache manager %p, protocol %d, %d caches\n",
184 mngr, protocol, mngr->cm_nassocs);
191 nl_cache_mngr_free(mngr);
196 * Add cache responsibility to cache manager
197 * @arg mngr Cache manager.
198 * @arg name Name of cache to keep track of
199 * @arg cb Function to be called upon changes.
201 * Allocates a new cache of the specified type and adds it to the manager.
202 * The operation will trigger a full dump request from the kernel to
203 * initially fill the contents of the cache. The manager will subscribe
204 * to the notification group of the cache to keep track of any further
207 * @return The newly allocated cache or NULL on failure.
209 struct nl_cache *nl_cache_mngr_add(struct nl_cache_mngr *mngr, const char *name,
212 struct nl_cache_ops *ops;
213 struct nl_cache *cache;
214 struct nl_af_group *grp;
217 ops = nl_cache_ops_lookup(name);
219 nl_error(ENOENT, "Unknown cache type");
223 if (ops->co_protocol != mngr->cm_protocol) {
224 nl_error(EINVAL, "Netlink protocol mismatch");
228 if (ops->co_groups == NULL) {
229 nl_error(EOPNOTSUPP, NULL);
233 for (i = 0; i < mngr->cm_nassocs; i++) {
234 if (mngr->cm_assocs[i].ca_cache &&
235 mngr->cm_assocs[i].ca_cache->c_ops == ops) {
236 nl_error(EEXIST, "Cache of this type already managed");
242 for (i = 0; i < mngr->cm_nassocs; i++)
243 if (!mngr->cm_assocs[i].ca_cache)
246 if (i >= mngr->cm_nassocs) {
247 mngr->cm_nassocs += 16;
248 mngr->cm_assocs = realloc(mngr->cm_assocs,
250 sizeof(struct nl_cache_assoc));
251 if (mngr->cm_assocs == NULL) {
255 NL_DBG(1, "Increased capacity of cache manager %p " \
256 "to %d\n", mngr, mngr->cm_nassocs);
261 cache = nl_cache_alloc(ops);
267 for (grp = ops->co_groups; grp->ag_group; grp++) {
268 err = nl_socket_add_membership(mngr->cm_handle, grp->ag_group);
270 goto errout_free_cache;
273 err = nl_cache_refill(mngr->cm_handle, cache);
275 goto errout_drop_membership;
277 mngr->cm_assocs[i].ca_cache = cache;
278 mngr->cm_assocs[i].ca_change = cb;
280 if (mngr->cm_flags & NL_AUTO_PROVIDE)
281 nl_cache_mngt_provide(cache);
283 NL_DBG(1, "Added cache %p <%s> to cache manager %p\n",
284 cache, nl_cache_name(cache), mngr);
288 errout_drop_membership:
289 for (grp = ops->co_groups; grp->ag_group; grp++)
290 nl_socket_drop_membership(mngr->cm_handle, grp->ag_group);
292 nl_cache_free(cache);
298 * Get file descriptor
299 * @arg mngr Cache Manager
301 * Get the file descriptor of the socket associated to the manager.
302 * This can be used to change socket options or monitor activity
303 * using poll()/select().
305 int nl_cache_mngr_get_fd(struct nl_cache_mngr *mngr)
307 return nl_socket_get_fd(mngr->cm_handle);
311 * Check for event notifications
312 * @arg mngr Cache Manager
313 * @arg timeout Upper limit poll() will block, in milliseconds.
315 * Causes poll() to be called to check for new event notifications
316 * being available. Automatically receives and handles available
319 * This functionally is ideally called regularly during an idle
322 * @return A positive value if at least one update was handled, 0
323 * for none, or a negative error code.
325 int nl_cache_mngr_poll(struct nl_cache_mngr *mngr, int timeout)
328 struct pollfd fds = {
329 .fd = nl_socket_get_fd(mngr->cm_handle),
333 NL_DBG(3, "Cache manager %p, poll() fd %d\n", mngr, fds.fd);
334 ret = poll(&fds, 1, timeout);
335 NL_DBG(3, "Cache manager %p, poll() returned %d\n", mngr, ret);
337 return nl_errno(errno);
342 return nl_cache_mngr_data_ready(mngr);
346 * Receive available event notifications
347 * @arg mngr Cache manager
349 * This function can be called if the socket associated to the manager
350 * contains updates to be received. This function should not be used
351 * if nl_cache_mngr_poll() is used.
353 * @return A positive value if at least one update was handled, 0
354 * for none, or a negative error code.
356 int nl_cache_mngr_data_ready(struct nl_cache_mngr *mngr)
360 err = nl_recvmsgs_default(mngr->cm_handle);
369 * @arg mngr Cache manager
371 * Release all resources after usage of a cache manager.
373 void nl_cache_mngr_free(struct nl_cache_mngr *mngr)
378 if (mngr->cm_handle) {
379 nl_close(mngr->cm_handle);
380 nl_handle_destroy(mngr->cm_handle);
383 free(mngr->cm_assocs);
386 NL_DBG(1, "Cache manager %p freed\n", mngr);