summaryrefslogtreecommitdiffstats
path: root/lib/cache_mngr.c
blob: f8a65e347d6ae8e1e57555cc37f5efe12516eb27 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
/*
 * lib/cache_mngr.c	Cache Manager
 *
 *	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 cache_mngt
 * @defgroup cache_mngr Manager
 * @brief Manager keeping caches up to date automatically.
 *
 * The cache manager keeps caches up to date automatically by listening to
 * netlink notifications and integrating the received information into the
 * existing cache.
 *
 * @note This functionality is still considered experimental.
 *
 * Related sections in the development guide:
 * - @core_doc{_cache_manager,Cache Manager}
 *
 * @{
 *
 * Header
 * ------
 * ~~~~{.c}
 * #include <netlink/cache.h>
 * ~~~~
 */

#include <netlink-private/netlink.h>
#include <netlink/netlink.h>
#include <netlink/cache.h>
#include <netlink/utils.h>

/** @cond SKIP */
#define NASSOC_INIT		16
#define NASSOC_EXPAND		8
/** @endcond */

static int include_cb(struct nl_object *obj, struct nl_parser_param *p)
{
	struct nl_cache_assoc *ca = p->pp_arg;
	struct nl_cache_ops *ops = ca->ca_cache->c_ops;

	NL_DBG(2, "Including object %p into cache %p\n", obj, ca->ca_cache);
#ifdef NL_DEBUG
	if (nl_debug >= 4)
		nl_object_dump(obj, &nl_debug_dp);
#endif

	if (ops->co_event_filter)
		if (ops->co_event_filter(ca->ca_cache, obj) != NL_OK)
			return 0;

	if (ops->co_include_event)
		return ops->co_include_event(ca->ca_cache, obj, ca->ca_change,
					     ca->ca_change_data);
	else
		return nl_cache_include(ca->ca_cache, obj, ca->ca_change, ca->ca_change_data);
}

static int event_input(struct nl_msg *msg, void *arg)
{
	struct nl_cache_mngr *mngr = arg;
	int protocol = nlmsg_get_proto(msg);
	int type = nlmsg_hdr(msg)->nlmsg_type;
	struct nl_cache_ops *ops;
	int i, n;
	struct nl_parser_param p = {
		.pp_cb = include_cb,
	};

	NL_DBG(2, "Cache manager %p, handling new message %p as event\n",
	       mngr, msg);
#ifdef NL_DEBUG
	if (nl_debug >= 4)
		nl_msg_dump(msg, stderr);
#endif

	if (mngr->cm_protocol != protocol)
		BUG();

	for (i = 0; i < mngr->cm_nassocs; i++) {
		if (mngr->cm_assocs[i].ca_cache) {
			ops = mngr->cm_assocs[i].ca_cache->c_ops;
			for (n = 0; ops->co_msgtypes[n].mt_id >= 0; n++)
				if (ops->co_msgtypes[n].mt_id == type)
					goto found;
		}
	}

	return NL_SKIP;

found:
	NL_DBG(2, "Associated message %p to cache %p\n",
	       msg, mngr->cm_assocs[i].ca_cache);
	p.pp_arg = &mngr->cm_assocs[i];

	return nl_cache_parse(ops, NULL, nlmsg_hdr(msg), &p);
}

/**
 * Allocate new cache manager
 * @arg sk		Netlink socket or NULL to auto allocate
 * @arg protocol	Netlink protocol this manager is used for
 * @arg flags		Flags (\c NL_AUTO_PROVIDE)
 * @arg result		Result pointer
 *
 * Allocates a new cache manager for the specified netlink protocol.
 *
 * 1. If sk is not specified (\c NULL) a netlink socket matching the
 *    specified protocol will be automatically allocated.
 *
 * 2. The socket will be put in non-blocking mode and sequence checking
 *    will be disabled regardless of whether the socket was provided by
 *    the caller or automatically allocated.
 *
 * 3. The socket will be connected.
 *
 * If the flag \c NL_AUTO_PROVIDE is specified, any cache added to the
 * manager will automatically be made available to other users using
 * nl_cache_mngt_provide().
 *
 * @note If the socket is provided by the caller, it is NOT recommended
 *       to use the socket for anything else besides receiving netlink
 *       notifications.
 *
 * @return 0 on success or a negative error code.
 */
int nl_cache_mngr_alloc(struct nl_sock *sk, int protocol, int flags,
			struct nl_cache_mngr **result)
{
	struct nl_cache_mngr *mngr;
	int err = -NLE_NOMEM;

	/* Catch abuse of flags */
	if (flags & NL_ALLOCATED_SOCK)
		BUG();

	mngr = calloc(1, sizeof(*mngr));
	if (!mngr)
		return -NLE_NOMEM;

	if (!sk) {
		if (!(sk = nl_socket_alloc()))
			goto errout;

		flags |= NL_ALLOCATED_SOCK;
	}

	mngr->cm_sock = sk;
	mngr->cm_nassocs = NASSOC_INIT;
	mngr->cm_protocol = protocol;
	mngr->cm_flags = flags;
	mngr->cm_assocs = calloc(mngr->cm_nassocs,
				 sizeof(struct nl_cache_assoc));
	if (!mngr->cm_assocs)
		goto errout;

	/* Required to receive async event notifications */
	nl_socket_disable_seq_check(mngr->cm_sock);

	if ((err = nl_connect(mngr->cm_sock, protocol) < 0))
		goto errout;

	if ((err = nl_socket_set_nonblocking(mngr->cm_sock) < 0))
		goto errout;

	/* Create and allocate socket for sync cache fills */
	mngr->cm_sync_sock = nl_socket_alloc();
	if (!mngr->cm_sync_sock)
		goto errout;
	if ((err = nl_connect(mngr->cm_sync_sock, protocol)) < 0)
		goto errout_free_sync_sock;

	NL_DBG(1, "Allocated cache manager %p, protocol %d, %d caches\n",
	       mngr, protocol, mngr->cm_nassocs);

	*result = mngr;
	return 0;

errout_free_sync_sock:
	nl_socket_free(mngr->cm_sync_sock);
errout:
	nl_cache_mngr_free(mngr);
	return err;
}

/**
 * Add cache to cache manager
 * @arg mngr		Cache manager.
 * @arg cache		Cache to be added to cache manager
 * @arg cb		Function to be called upon changes.
 * @arg data		Argument passed on to change callback
 *
 * Adds cache to the manager. The operation will trigger a full
 * dump request from the kernel to initially fill the contents
 * of the cache. The manager will subscribe to the notification group
 * of the cache and keep track of any further changes.
 *
 * The user is responsible for calling nl_cache_mngr_poll() or monitor
 * the socket and call nl_cache_mngr_data_ready() to allow the library
 * to process netlink notification events.
 *
 * @see nl_cache_mngr_poll()
 * @see nl_cache_mngr_data_ready()
 *
 * @return 0 on success or a negative error code.
 * @return -NLE_PROTO_MISMATCH Protocol mismatch between cache manager and
 * 			       cache type
 * @return -NLE_OPNOTSUPP Cache type does not support updates
 * @return -NLE_EXIST Cache of this type already being managed
 */
int nl_cache_mngr_add_cache(struct nl_cache_mngr *mngr, struct nl_cache *cache,
		      change_func_t cb, void *data)
{
	struct nl_cache_ops *ops;
	struct nl_af_group *grp;
	int err, i;

	ops = cache->c_ops;
	if (!ops)
		return -NLE_INVAL;

	if (ops->co_protocol != mngr->cm_protocol)
		return -NLE_PROTO_MISMATCH;

	if (ops->co_groups == NULL)
		return -NLE_OPNOTSUPP;

	for (i = 0; i < mngr->cm_nassocs; i++)
		if (mngr->cm_assocs[i].ca_cache &&
		    mngr->cm_assocs[i].ca_cache->c_ops == ops)
			return -NLE_EXIST;

retry:
	for (i = 0; i < mngr->cm_nassocs; i++)
		if (!mngr->cm_assocs[i].ca_cache)
			break;

	if (i >= mngr->cm_nassocs) {
		mngr->cm_nassocs += NASSOC_EXPAND;
		mngr->cm_assocs = realloc(mngr->cm_assocs,
					  mngr->cm_nassocs *
					  sizeof(struct nl_cache_assoc));
		if (mngr->cm_assocs == NULL)
			return -NLE_NOMEM;

		memset(mngr->cm_assocs + (mngr->cm_nassocs - NASSOC_EXPAND), 0,
		       NASSOC_EXPAND * sizeof(struct nl_cache_assoc));

		NL_DBG(1, "Increased capacity of cache manager %p " \
			  "to %d\n", mngr, mngr->cm_nassocs);
		goto retry;
	}

	for (grp = ops->co_groups; grp->ag_group; grp++) {
		err = nl_socket_add_membership(mngr->cm_sock, grp->ag_group);
		if (err < 0)
			return err;
	}

	err = nl_cache_refill(mngr->cm_sync_sock, cache);
	if (err < 0)
		goto errout_drop_membership;

	mngr->cm_assocs[i].ca_cache = cache;
	mngr->cm_assocs[i].ca_change = cb;
	mngr->cm_assocs[i].ca_change_data = data;

	if (mngr->cm_flags & NL_AUTO_PROVIDE)
		nl_cache_mngt_provide(cache);

	NL_DBG(1, "Added cache %p <%s> to cache manager %p\n",
	       cache, nl_cache_name(cache), mngr);

	return 0;

errout_drop_membership:
	for (grp = ops->co_groups; grp->ag_group; grp++)
		nl_socket_drop_membership(mngr->cm_sock, grp->ag_group);

	return err;
}

/**
 * Add cache to cache manager
 * @arg mngr		Cache manager.
 * @arg name		Name of cache to keep track of
 * @arg cb		Function to be called upon changes.
 * @arg data		Argument passed on to change callback
 * @arg result		Pointer to store added cache (optional)
 *
 * Allocates a new cache of the specified type and adds it to the manager.
 * The operation will trigger a full dump request from the kernel to
 * initially fill the contents of the cache. The manager will subscribe
 * to the notification group of the cache and keep track of any further
 * changes.
 *
 * The user is responsible for calling nl_cache_mngr_poll() or monitor
 * the socket and call nl_cache_mngr_data_ready() to allow the library
 * to process netlink notification events.
 *
 * @see nl_cache_mngr_poll()
 * @see nl_cache_mngr_data_ready()
 *
 * @return 0 on success or a negative error code.
 * @return -NLE_NOCACHE Unknown cache type
 * @return -NLE_PROTO_MISMATCH Protocol mismatch between cache manager and
 * 			       cache type
 * @return -NLE_OPNOTSUPP Cache type does not support updates
 * @return -NLE_EXIST Cache of this type already being managed
 */
int nl_cache_mngr_add(struct nl_cache_mngr *mngr, const char *name,
		      change_func_t cb, void *data, struct nl_cache **result)
{
	struct nl_cache_ops *ops;
	struct nl_cache *cache;
	int err;

	ops = nl_cache_ops_lookup_safe(name);
	if (!ops)
		return -NLE_NOCACHE;

	cache = nl_cache_alloc(ops);
	nl_cache_ops_put(ops);
	if (!cache)
		return -NLE_NOMEM;

	err = nl_cache_mngr_add_cache(mngr, cache, cb, data);
	if (err < 0)
		goto errout_free_cache;

	*result = cache;
	return 0;

errout_free_cache:
	nl_cache_free(cache);

	return err;
}

/**
 * Get socket file descriptor
 * @arg mngr		Cache Manager
 *
 * Get the file descriptor of the socket associated with the manager.
 *
 * @note Do not use the socket for anything besides receiving
 *       notifications.
 */
int nl_cache_mngr_get_fd(struct nl_cache_mngr *mngr)
{
	return nl_socket_get_fd(mngr->cm_sock);
}

/**
 * Check for event notifications
 * @arg mngr		Cache Manager
 * @arg timeout		Upper limit poll() will block, in milliseconds.
 *
 * Causes poll() to be called to check for new event notifications
 * being available. Calls nl_cache_mngr_data_ready() to process
 * available data.
 *
 * This functionally is ideally called regularly during an idle
 * period.
 *
 * A timeout can be specified in milliseconds to limit the time the
 * function will wait for updates.
 *
 * @see nl_cache_mngr_data_ready()
 *
 * @return The number of messages processed or a negative error code.
 */
int nl_cache_mngr_poll(struct nl_cache_mngr *mngr, int timeout)
{
	int ret;
	struct pollfd fds = {
		.fd = nl_socket_get_fd(mngr->cm_sock),
		.events = POLLIN,
	};

	NL_DBG(3, "Cache manager %p, poll() fd %d\n", mngr, fds.fd);
	ret = poll(&fds, 1, timeout);
	NL_DBG(3, "Cache manager %p, poll() returned %d\n", mngr, ret);
	if (ret < 0)
		return -nl_syserr2nlerr(errno);

	/* No events, return */
	if (ret == 0)
		return 0;

	return nl_cache_mngr_data_ready(mngr);
}

/**
 * Receive available event notifications
 * @arg mngr		Cache manager
 *
 * This function can be called if the socket associated to the manager
 * contains updates to be received. This function should only be used
 * if nl_cache_mngr_poll() is not used.
 *
 * The function will process messages until there is no more data to
 * be read from the socket.
 *
 * @see nl_cache_mngr_poll()
 *
 * @return The number of messages processed or a negative error code.
 */
int nl_cache_mngr_data_ready(struct nl_cache_mngr *mngr)
{
	int err, nread = 0;
	struct nl_cb *cb;

	NL_DBG(2, "Cache manager %p, reading new data from fd %d\n",
	       mngr, nl_socket_get_fd(mngr->cm_sock));

	cb = nl_cb_clone(mngr->cm_sock->s_cb);
	if (cb == NULL)
		return -NLE_NOMEM;

	nl_cb_set(cb, NL_CB_VALID, NL_CB_CUSTOM, event_input, mngr);

	while ((err = nl_recvmsgs_report(mngr->cm_sock, cb)) > 0) {
		NL_DBG(2, "Cache manager %p, recvmsgs read %d messages\n",
		       mngr, err);
		nread += err;
	}

	nl_cb_put(cb);
	if (err < 0)
		return err;

	return nread;
}

/**
 * Print information about cache manager
 * @arg mngr		Cache manager
 * @arg p		Dumping parameters
 *
 * Prints information about the cache manager including all managed caches.
 *
 * @note This is a debugging function.
 */
void nl_cache_mngr_info(struct nl_cache_mngr *mngr, struct nl_dump_params *p)
{
	char buf[128];
	int i;

	nl_dump_line(p, "cache-manager <%p>\n", mngr);
	nl_dump_line(p, "  .protocol = %s\n",
		     nl_nlfamily2str(mngr->cm_protocol, buf, sizeof(buf)));
	nl_dump_line(p, "  .flags    = %#x\n", mngr->cm_flags);
	nl_dump_line(p, "  .nassocs  = %u\n", mngr->cm_nassocs);
	nl_dump_line(p, "  .sock     = <%p>\n", mngr->cm_sock);

	for (i = 0; i < mngr->cm_nassocs; i++) {
		struct nl_cache_assoc *assoc = &mngr->cm_assocs[i];

		if (assoc->ca_cache) {
			nl_dump_line(p, "  .cache[%d] = <%p> {\n", i, assoc->ca_cache);
			nl_dump_line(p, "    .name = %s\n", assoc->ca_cache->c_ops->co_name);
			nl_dump_line(p, "    .change_func = <%p>\n", assoc->ca_change);
			nl_dump_line(p, "    .change_data = <%p>\n", assoc->ca_change_data);
			nl_dump_line(p, "    .nitems = %u\n", nl_cache_nitems(assoc->ca_cache));
			nl_dump_line(p, "    .objects = {\n");

			p->dp_prefix += 6;
			nl_cache_dump(assoc->ca_cache, p);
			p->dp_prefix -= 6;

			nl_dump_line(p, "    }\n");
			nl_dump_line(p, "  }\n");
		}
	}
}

/**
 * Free cache manager and all caches.
 * @arg mngr		Cache manager.
 *
 * Release all resources held by a cache manager.
 */
void nl_cache_mngr_free(struct nl_cache_mngr *mngr)
{
	int i;

	if (!mngr)
		return;

	if (mngr->cm_sock)
		nl_close(mngr->cm_sock);

	if (mngr->cm_sync_sock) {
		nl_close(mngr->cm_sync_sock);
		nl_socket_free(mngr->cm_sync_sock);
	}

	if (mngr->cm_flags & NL_ALLOCATED_SOCK)
		nl_socket_free(mngr->cm_sock);

	for (i = 0; i < mngr->cm_nassocs; i++) {
		if (mngr->cm_assocs[i].ca_cache) {
			nl_cache_mngt_unprovide(mngr->cm_assocs[i].ca_cache);
			nl_cache_free(mngr->cm_assocs[i].ca_cache);
		}
	}

	free(mngr->cm_assocs);
	free(mngr);

	NL_DBG(1, "Cache manager %p freed\n", mngr);
}

/** @} */