1 /*
2 * lib/cache_mngr.c Cache Manager
3 *
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
7 * of the License.
8 *
9 * Copyright (c) 2003-2008 Thomas Graf <tgraf@suug.ch>
10 */
11
12 /**
13 * @ingroup cache_mngt
14 * @defgroup cache_mngr Manager
15 * @brief Helps keeping caches up to date.
16 *
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.
28 *
29 * @code
30 * App libnl Kernel
31 * | |
32 * +-----------------+ [ notification, link change ]
33 * | | Cache Manager | | [ (IFF_UP | IFF_RUNNING) ]
34 * | | |
35 * | | +------------+| | | [ notification, new addr ]
36 * <-------|---| route/link |<-------(async)--+ [ 10.0.1.1/32 dev eth1 ]
37 * | | +------------+| | |
38 * | +------------+| |
39 * <---|---|---| route/addr |<------|-(async)--------------+
40 * | +------------+|
41 * | | +------------+| |
42 * <-------|---| ... ||
43 * | | +------------+| |
44 * +-----------------+
45 * | |
46 * @endcode
47 *
48 * @par 1) Creating a new cache manager
49 * @code
50 * struct nl_cache_mngr *mngr;
51 *
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);
55 * @endcode
56 *
57 * @par 2) Keep track of a cache
58 * @code
59 * struct nl_cache *cache;
60 *
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");
65 * @endcode
66 *
67 * @par 3) Make the manager receive updates
68 * @code
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, ...);
74 * }
75 * @endcode
76 *
77 * @par 4) Release cache manager
78 * @code
79 * nl_cache_mngr_free(mngr);
80 * @endcode
81 * @{
82 */
83
84 #include <netlink-local.h>
85 #include <netlink/netlink.h>
86 #include <netlink/cache.h>
87 #include <netlink/utils.h>
88
include_cb(struct nl_object * obj,struct nl_parser_param * p)89 static int include_cb(struct nl_object *obj, struct nl_parser_param *p)
90 {
91 struct nl_cache_assoc *ca = p->pp_arg;
92
93 NL_DBG(2, "Including object %p into cache %p\n", obj, ca->ca_cache);
94 #ifdef NL_DEBUG
95 if (nl_debug >= 4)
96 nl_object_dump(obj, &nl_debug_dp);
97 #endif
98 return nl_cache_include(ca->ca_cache, obj, ca->ca_change, ca->ca_change_data);
99 }
100
event_input(struct nl_msg * msg,void * arg)101 static int event_input(struct nl_msg *msg, void *arg)
102 {
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;
107 int i, n;
108 struct nl_parser_param p = {
109 .pp_cb = include_cb,
110 };
111
112 NL_DBG(2, "Cache manager %p, handling new message %p as event\n",
113 mngr, msg);
114 #ifdef NL_DEBUG
115 if (nl_debug >= 4)
116 nl_msg_dump(msg, stderr);
117 #endif
118
119 if (mngr->cm_protocol != protocol)
120 BUG();
121
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)
127 goto found;
128 }
129 }
130
131 return NL_SKIP;
132
133 found:
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];
137
138 return nl_cache_parse(ops, NULL, nlmsg_hdr(msg), &p);
139 }
140
141 /**
142 * Allocate new cache manager
143 * @arg sk Netlink socket.
144 * @arg protocol Netlink Protocol this manager is used for
145 * @arg flags Flags
146 *
147 * @return Newly allocated cache manager or NULL on failure.
148 */
nl_cache_mngr_alloc(struct nl_sock * sk,int protocol,int flags,struct nl_cache_mngr ** result)149 int nl_cache_mngr_alloc(struct nl_sock *sk, int protocol, int flags,
150 struct nl_cache_mngr **result)
151 {
152 struct nl_cache_mngr *mngr;
153 int err = -NLE_NOMEM;
154
155 if (sk == NULL)
156 BUG();
157
158 mngr = calloc(1, sizeof(*mngr));
159 if (!mngr)
160 goto errout;
161
162 mngr->cm_handle = sk;
163 mngr->cm_nassocs = 32;
164 mngr->cm_protocol = protocol;
165 mngr->cm_flags = flags;
166 mngr->cm_assocs = calloc(mngr->cm_nassocs,
167 sizeof(struct nl_cache_assoc));
168 if (!mngr->cm_assocs)
169 goto errout;
170
171 nl_socket_modify_cb(mngr->cm_handle, NL_CB_VALID, NL_CB_CUSTOM,
172 event_input, mngr);
173
174 /* Required to receive async event notifications */
175 nl_socket_disable_seq_check(mngr->cm_handle);
176
177 if ((err = nl_connect(mngr->cm_handle, protocol) < 0))
178 goto errout;
179
180 if ((err = nl_socket_set_nonblocking(mngr->cm_handle) < 0))
181 goto errout;
182
183 NL_DBG(1, "Allocated cache manager %p, protocol %d, %d caches\n",
184 mngr, protocol, mngr->cm_nassocs);
185
186 *result = mngr;
187 return 0;
188
189 errout:
190 nl_cache_mngr_free(mngr);
191 return err;
192 }
193
194 /**
195 * Add cache responsibility to cache manager
196 * @arg mngr Cache manager.
197 * @arg name Name of cache to keep track of
198 * @arg cb Function to be called upon changes.
199 * @arg result Pointer to store added cache.
200 *
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
205 * changes.
206 *
207 * @return 0 on success or a negative error code.
208 */
nl_cache_mngr_add(struct nl_cache_mngr * mngr,const char * name,change_func_t cb,void * data,struct nl_cache ** result)209 int nl_cache_mngr_add(struct nl_cache_mngr *mngr, const char *name,
210 change_func_t cb, void *data, struct nl_cache **result)
211 {
212 struct nl_cache_ops *ops;
213 struct nl_cache *cache;
214 struct nl_af_group *grp;
215 int err, i;
216
217 ops = nl_cache_ops_lookup(name);
218 if (!ops)
219 return -NLE_NOCACHE;
220
221 if (ops->co_protocol != mngr->cm_protocol)
222 return -NLE_PROTO_MISMATCH;
223
224 if (ops->co_groups == NULL)
225 return -NLE_OPNOTSUPP;
226
227 for (i = 0; i < mngr->cm_nassocs; i++)
228 if (mngr->cm_assocs[i].ca_cache &&
229 mngr->cm_assocs[i].ca_cache->c_ops == ops)
230 return -NLE_EXIST;
231
232 retry:
233 for (i = 0; i < mngr->cm_nassocs; i++)
234 if (!mngr->cm_assocs[i].ca_cache)
235 break;
236
237 if (i >= mngr->cm_nassocs) {
238 mngr->cm_nassocs += 16;
239 mngr->cm_assocs = realloc(mngr->cm_assocs,
240 mngr->cm_nassocs *
241 sizeof(struct nl_cache_assoc));
242 if (mngr->cm_assocs == NULL)
243 return -NLE_NOMEM;
244 else {
245 NL_DBG(1, "Increased capacity of cache manager %p " \
246 "to %d\n", mngr, mngr->cm_nassocs);
247 goto retry;
248 }
249 }
250
251 cache = nl_cache_alloc(ops);
252 if (!cache)
253 return -NLE_NOMEM;
254
255 for (grp = ops->co_groups; grp->ag_group; grp++) {
256 err = nl_socket_add_membership(mngr->cm_handle, grp->ag_group);
257 if (err < 0)
258 goto errout_free_cache;
259 }
260
261 err = nl_cache_refill(mngr->cm_handle, cache);
262 if (err < 0)
263 goto errout_drop_membership;
264
265 mngr->cm_assocs[i].ca_cache = cache;
266 mngr->cm_assocs[i].ca_change = cb;
267 mngr->cm_assocs[i].ca_change_data = data;
268
269 if (mngr->cm_flags & NL_AUTO_PROVIDE)
270 nl_cache_mngt_provide(cache);
271
272 NL_DBG(1, "Added cache %p <%s> to cache manager %p\n",
273 cache, nl_cache_name(cache), mngr);
274
275 *result = cache;
276 return 0;
277
278 errout_drop_membership:
279 for (grp = ops->co_groups; grp->ag_group; grp++)
280 nl_socket_drop_membership(mngr->cm_handle, grp->ag_group);
281 errout_free_cache:
282 nl_cache_free(cache);
283
284 return err;
285 }
286
287 /**
288 * Get file descriptor
289 * @arg mngr Cache Manager
290 *
291 * Get the file descriptor of the socket associated to the manager.
292 * This can be used to change socket options or monitor activity
293 * using poll()/select().
294 */
nl_cache_mngr_get_fd(struct nl_cache_mngr * mngr)295 int nl_cache_mngr_get_fd(struct nl_cache_mngr *mngr)
296 {
297 return nl_socket_get_fd(mngr->cm_handle);
298 }
299
300 /**
301 * Check for event notifications
302 * @arg mngr Cache Manager
303 * @arg timeout Upper limit poll() will block, in milliseconds.
304 *
305 * Causes poll() to be called to check for new event notifications
306 * being available. Automatically receives and handles available
307 * notifications.
308 *
309 * This functionally is ideally called regularly during an idle
310 * period.
311 *
312 * @return A positive value if at least one update was handled, 0
313 * for none, or a negative error code.
314 */
nl_cache_mngr_poll(struct nl_cache_mngr * mngr,int timeout)315 int nl_cache_mngr_poll(struct nl_cache_mngr *mngr, int timeout)
316 {
317 int ret;
318 struct pollfd fds = {
319 .fd = nl_socket_get_fd(mngr->cm_handle),
320 .events = POLLIN,
321 };
322
323 NL_DBG(3, "Cache manager %p, poll() fd %d\n", mngr, fds.fd);
324 ret = poll(&fds, 1, timeout);
325 NL_DBG(3, "Cache manager %p, poll() returned %d\n", mngr, ret);
326 if (ret < 0)
327 return -nl_syserr2nlerr(errno);
328
329 if (ret == 0)
330 return 0;
331
332 return nl_cache_mngr_data_ready(mngr);
333 }
334
335 /**
336 * Receive available event notifications
337 * @arg mngr Cache manager
338 *
339 * This function can be called if the socket associated to the manager
340 * contains updates to be received. This function should not be used
341 * if nl_cache_mngr_poll() is used.
342 *
343 * @return A positive value if at least one update was handled, 0
344 * for none, or a negative error code.
345 */
nl_cache_mngr_data_ready(struct nl_cache_mngr * mngr)346 int nl_cache_mngr_data_ready(struct nl_cache_mngr *mngr)
347 {
348 int err;
349
350 err = nl_recvmsgs_default(mngr->cm_handle);
351 if (err < 0)
352 return err;
353
354 return 1;
355 }
356
357 /**
358 * Free cache manager and all caches.
359 * @arg mngr Cache manager.
360 *
361 * Release all resources after usage of a cache manager.
362 */
nl_cache_mngr_free(struct nl_cache_mngr * mngr)363 void nl_cache_mngr_free(struct nl_cache_mngr *mngr)
364 {
365 int i;
366
367 if (!mngr)
368 return;
369
370 if (mngr->cm_handle)
371 nl_close(mngr->cm_handle);
372
373 for (i = 0; i < mngr->cm_nassocs; i++)
374 if (mngr->cm_assocs[i].ca_cache)
375 nl_cache_free(mngr->cm_assocs[i].ca_cache);
376
377 free(mngr->cm_assocs);
378 free(mngr);
379
380 NL_DBG(1, "Cache manager %p freed\n", mngr);
381 }
382
383 /** @} */
384