aboutsummaryrefslogtreecommitdiffstats
path: root/src/msgb.c
blob: 5a154e56bd467885387e467fcfe7f9670b3e97d6 (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
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
/* (C) 2008 by Harald Welte <laforge@gnumonks.org>
 * (C) 2010 by Holger Hans Peter Freyther <zecke@selfish.org>
 * All Rights Reserved
 *
 * SPDX-License-Identifier: GPL-2.0+
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 */

/*! \addtogroup msgb
 *  @{
 *
 *  libosmocore message buffers, inspired by Linux kernel skbuff
 *
 *  Inspired by the 'struct skbuff' of the Linux kernel, we implement a
 *  'struct msgb' which we use for handling network
 *  packets aka messages aka PDUs.
 *
 *  A msgb consists of
 *  	* a header with some metadata, such as
 *  	  * a linked list header for message queues or the like
 *  	  * pointers to the headers of various protocol layers inside
 *  	    the packet
 *  	* a data section consisting of
 *  	  * headroom, i.e. space in front of the message, to allow
 *  	    for additional headers being pushed in front of the current
 *  	    data
 *  	  * the currently occupied data for the message
 *  	  * tailroom, i.e. space at the end of the message, to
 *  	    allow more data to be added after the end of the current
 *  	    data
 *
 *  We have plenty of utility functions around the \ref msgb:
 *  	* allocation / release
 *  	* enqueue / dequeue from/to message queues
 *  	* prepending (pushing) and appending (putting) data
 *  	* copying / resizing
 *  	* hex-dumping to a string for debug purposes
 *
 * \file msgb.c
 */

#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <inttypes.h>
#include <stdarg.h>
#include <errno.h>

#include <osmocom/core/msgb.h>
#include <osmocom/core/talloc.h>
#include <osmocom/core/logging.h>

/*! Allocate a new message buffer from given talloc cotext
 * \param[in] ctx talloc context from which to allocate
 * \param[in] size Length in octets, including headroom
 * \param[in] name Human-readable name to be associated with msgb
 * \returns dynamically-allocated \ref msgb
 *
 * This function allocates a 'struct msgb' as well as the underlying
 * memory buffer for the actual message data (size specified by \a size)
 * using the talloc memory context previously set by \ref msgb_set_talloc_ctx
 */
struct msgb *msgb_alloc_c(const void *ctx, uint16_t size, const char *name)
{
	struct msgb *msg;

	msg = talloc_named_const(ctx, sizeof(*msg) + size, name);
	if (!msg) {
		LOGP(DLGLOBAL, LOGL_FATAL, "Unable to allocate a msgb: "
			"name='%s', size=%u\n", name, size);
		return NULL;
	}

	/* Manually zero-initialize allocated memory */
	memset(msg, 0x00, sizeof(*msg) + size);

	msg->data_len = size;
	msg->len = 0;
	msg->data = msg->_data;
	msg->head = msg->_data;
	msg->tail = msg->_data;

	return msg;
}

/* default msgb allocation context for msgb_alloc() */
void *tall_msgb_ctx = NULL;

/*! Allocate a new message buffer from tall_msgb_ctx
 * \param[in] size Length in octets, including headroom
 * \param[in] name Human-readable name to be associated with msgb
 * \returns dynamically-allocated \ref msgb
 *
 * This function allocates a 'struct msgb' as well as the underlying
 * memory buffer for the actual message data (size specified by \a size)
 * using the talloc memory context previously set by \ref msgb_set_talloc_ctx
 */
struct msgb *msgb_alloc(uint16_t size, const char *name)
{
	return msgb_alloc_c(tall_msgb_ctx, size, name);
}


/*! Release given message buffer
 * \param[in] m Message buffer to be freed
 */
void msgb_free(struct msgb *m)
{
	talloc_free(m);
}

/*! Enqueue message buffer to tail of a queue
 * \param[in] queue linked list header of queue
 * \param[in] msg message buffer to be added to the queue
 *
 * The function will append the specified message buffer \a msg to the
 * queue implemented by \ref llist_head \a queue
 */
void msgb_enqueue(struct llist_head *queue, struct msgb *msg)
{
	llist_add_tail(&msg->list, queue);
}

/*! Dequeue message buffer from head of queue
 * \param[in] queue linked list header of queue
 * \returns message buffer (if any) or NULL if queue empty
 *
 * The function will remove the first message buffer from the queue
 * implemented by \ref llist_head \a queue.
 */
struct msgb *msgb_dequeue(struct llist_head *queue)
{
	struct llist_head *lh;

	if (llist_empty(queue))
		return NULL;

	lh = queue->next;

	if (lh) {
		llist_del(lh);
		return llist_entry(lh, struct msgb, list);
	} else
		return NULL;
}

/*! Re-set all message buffer pointers
 *  \param[in] msg message buffer that is to be resetted
 *
 * This will re-set the various internal pointers into the underlying
 * message buffer, i.e. remove all headroom and treat the msgb as
 * completely empty.  It also initializes the control buffer to zero.
 */
void msgb_reset(struct msgb *msg)
{
	msg->len = 0;
	msg->data = msg->_data;
	msg->head = msg->_data;
	msg->tail = msg->_data;

	msg->trx = NULL;
	msg->lchan = NULL;
	msg->l2h = NULL;
	msg->l3h = NULL;
	msg->l4h = NULL;

	memset(&msg->cb, 0, sizeof(msg->cb));
}

/*! get pointer to data section of message buffer
 *  \param[in] msg message buffer
 *  \returns pointer to data section of message buffer
 */
uint8_t *msgb_data(const struct msgb *msg)
{
	return msg->data;
}

/*! Compare and print: check data in msgb against given data and print errors if any
 *  \param[in] file text prefix, usually __FILE__, ignored if print == false
 *  \param[in] line numeric prefix, usually __LINE__, ignored if print == false
 *  \param[in] func text prefix, usually __func__, ignored if print == false
 *  \param[in] level while layer (L1, L2 etc) data should be compared against
 *  \param[in] msg message buffer
 *  \param[in] data expected data
 *  \param[in] len length of data
 *  \param[in] print boolean indicating whether we should print anything to stdout
 *  \returns boolean indicating whether msgb content is equal to a given data
 *
 * This function is not intended to be called directly but rather used through corresponding macro wrappers.
 */
bool _msgb_eq(const char *file, size_t line, const char *func, uint8_t level,
	      const struct msgb *msg, const uint8_t *data, size_t len, bool print)
{
	const char *m_dump;
	unsigned int m_len, i;
	uint8_t *m_data;

	if (!msg) {
		if (print)
			LOGPSRC(DLGLOBAL, LOGL_FATAL, file, line, "%s() NULL msg comparison\n", func);
		return false;
	}

	if (!data) {
		if (print)
			LOGPSRC(DLGLOBAL, LOGL_FATAL, file, line, "%s() NULL comparison data\n", func);
		return false;
	}

	switch (level) {
	case 0:
		m_len = msgb_length(msg);
		m_data = msgb_data(msg);
		m_dump = print ? msgb_hexdump(msg) : NULL;
		break;
	case 1:
		m_len = msgb_l1len(msg);
		m_data = msgb_l1(msg);
		m_dump = print ? msgb_hexdump_l1(msg) : NULL;
		break;
	case 2:
		m_len = msgb_l2len(msg);
		m_data = msgb_l2(msg);
		m_dump = print ? msgb_hexdump_l2(msg) : NULL;
		break;
	case 3:
		m_len = msgb_l3len(msg);
		m_data = msgb_l3(msg);
		m_dump = print ? msgb_hexdump_l3(msg) : NULL;
		break;
	case 4:
		m_len = msgb_l4len(msg);
		m_data = msgb_l4(msg);
		m_dump = print ? msgb_hexdump_l4(msg) : NULL;
		break;
	default:
		LOGPSRC(DLGLOBAL, LOGL_FATAL, file, line,
			"%s() FIXME: unexpected comparison level %u\n", func, level);
		return false;
	}

	if (m_len != len) {
		if (print)
			LOGPSRC(DLGLOBAL, LOGL_FATAL, file, line,
				"%s() Length mismatch: %d != %zu, %s\n", func, m_len, len, m_dump);
		return false;
	}

	if (memcmp(m_data, data, len) == 0)
		return true;

	if (!print)
		return false;

	LOGPSRC(DLGLOBAL, LOGL_FATAL, file, line,
		"%s() L%u data mismatch:\nexpected %s\n         ", func, level, osmo_hexdump(data, len));

	for(i = 0; i < len; i++)
		if (data[i] != m_data[i]) {
			LOGPC(DLGLOBAL, LOGL_FATAL, "!!\n");
			break;
		} else
			LOGPC(DLGLOBAL, LOGL_FATAL, ".. ");

	LOGPC(DLGLOBAL, LOGL_FATAL, "    msgb %s\n", osmo_hexdump(m_data, len));

	return false;
}

/*! get length of message buffer
 *  \param[in] msg message buffer
 *  \returns length of data section in message buffer
 */
uint16_t msgb_length(const struct msgb *msg)
{
	return msg->len;
}

/*! Set the talloc context for \ref msgb_alloc
 * Deprecated, use msgb_talloc_ctx_init() instead.
 *  \param[in] ctx talloc context to be used as root for msgb allocations
 */
void msgb_set_talloc_ctx(void *ctx)
{
	tall_msgb_ctx = ctx;
}

/*! Initialize a msgb talloc context for \ref msgb_alloc.
 * Create a talloc context called "msgb". If \a pool_size is 0, create a named
 * const as msgb talloc context. If \a pool_size is nonzero, create a talloc
 * pool, possibly for faster msgb allocations (see talloc_pool()).
 *  \param[in] root_ctx talloc context used as parent for the new "msgb" ctx.
 *  \param[in] pool_size if nonzero, create a talloc pool of this size.
 *  \returns the new msgb talloc context, e.g. for reporting
 */
void *msgb_talloc_ctx_init(void *root_ctx, unsigned int pool_size)
{
	if (!pool_size)
		tall_msgb_ctx = talloc_size(root_ctx, 0);
	else
		tall_msgb_ctx = talloc_pool(root_ctx, pool_size);
	talloc_set_name_const(tall_msgb_ctx, "msgb");
	return tall_msgb_ctx;
}

/*! Copy an msgb.
 *
 *  This function allocates a new msgb, copies the data buffer of msg,
 *  and adjusts the pointers (incl l1h-l4h) accordingly. The cb part
 *  is not copied.
 *  \param[in] msg  The old msgb object
 *  \param[in] name Human-readable name to be associated with msgb
 */
struct msgb *msgb_copy_c(const void *ctx, const struct msgb *msg, const char *name)
{
	struct msgb *new_msg;

	new_msg = msgb_alloc_c(ctx, msg->data_len, name);
	if (!new_msg)
		return NULL;

	/* copy data */
	memcpy(new_msg->_data, msg->_data, new_msg->data_len);

	/* copy header */
	new_msg->len = msg->len;
	new_msg->data += msg->data - msg->_data;
	new_msg->head += msg->head - msg->_data;
	new_msg->tail += msg->tail - msg->_data;

	if (msg->l1h)
		new_msg->l1h = new_msg->_data + (msg->l1h - msg->_data);
	if (msg->l2h)
		new_msg->l2h = new_msg->_data + (msg->l2h - msg->_data);
	if (msg->l3h)
		new_msg->l3h = new_msg->_data + (msg->l3h - msg->_data);
	if (msg->l4h)
		new_msg->l4h = new_msg->_data + (msg->l4h - msg->_data);

	return new_msg;
}

/*! Copy an msgb.
 *
 *  This function allocates a new msgb, copies the data buffer of msg,
 *  and adjusts the pointers (incl l1h-l4h) accordingly. The cb part
 *  is not copied.
 *  \param[in] msg  The old msgb object
 *  \param[in] name Human-readable name to be associated with msgb
 */
struct msgb *msgb_copy(const struct msgb *msg, const char *name)
{
	return msgb_copy_c(tall_msgb_ctx, msg, name);
}

/*! Resize an area within an msgb
 *
 *  This resizes a sub area of the msgb data and adjusts the pointers (incl
 *  l1h-l4h) accordingly. The cb part is not updated. If the area is extended,
 *  the contents of the extension is undefined. The complete sub area must be a
 *  part of [data,tail].
 *
 *  \param[inout] msg       The msgb object
 *  \param[in]    area      A pointer to the sub-area
 *  \param[in]    old_size  The old size of the sub-area
 *  \param[in]    new_size  The new size of the sub-area
 *  \returns 0 on success, -1 if there is not enough space to extend the area
 */
int msgb_resize_area(struct msgb *msg, uint8_t *area,
			    int old_size, int new_size)
{
	int rc;
	uint8_t *post_start = area + old_size;
	int pre_len = area - msg->data;
	int post_len = msg->len - old_size - pre_len;
	int delta_size = new_size - old_size;

	if (old_size < 0 || new_size < 0)
		MSGB_ABORT(msg, "Negative sizes are not allowed\n");
	if (area < msg->data || post_start > msg->tail)
		MSGB_ABORT(msg, "Sub area is not fully contained in the msg data\n");

	if (delta_size == 0)
		return 0;

	if (delta_size > 0) {
		rc = msgb_trim(msg, msg->len + delta_size);
		if (rc < 0)
			return rc;
	}

	memmove(area + new_size, area + old_size, post_len);

	if (msg->l1h >= post_start)
		msg->l1h += delta_size;
	if (msg->l2h >= post_start)
		msg->l2h += delta_size;
	if (msg->l3h >= post_start)
		msg->l3h += delta_size;
	if (msg->l4h >= post_start)
		msg->l4h += delta_size;

	if (delta_size < 0)
		msgb_trim(msg, msg->len + delta_size);

	return 0;
}


/*! fill user-provided buffer with hexdump of the msg.
 * \param[out] buf caller-allocated buffer for output string
 * \param[in] buf_len length of buf
 * \param[in] msg message buffer to be dumped
 * \returns buf
 */
char *msgb_hexdump_buf(char *buf, size_t buf_len, const struct msgb *msg)
{
	int buf_offs = 0;
	int nchars;
	const unsigned char *start = msg->data;
	const unsigned char *lxhs[4];
	int i;

	lxhs[0] = msg->l1h;
	lxhs[1] = msg->l2h;
	lxhs[2] = msg->l3h;
	lxhs[3] = msg->l4h;

	for (i = 0; i < ARRAY_SIZE(lxhs); i++) {
		if (!lxhs[i])
			continue;

		if (lxhs[i] < msg->head)
			continue;
		if (lxhs[i] > msg->head + msg->data_len)
			continue;
		if (lxhs[i] > msg->tail)
			continue;
		if (lxhs[i] < msg->data || lxhs[i] > msg->tail) {
			nchars = snprintf(buf + buf_offs, buf_len - buf_offs,
					  "(L%d=data%+" PRIdPTR ") ",
					  i+1, lxhs[i] - msg->data);
			buf_offs += nchars;
			continue;
		}
		if (lxhs[i] < start) {
			nchars = snprintf(buf + buf_offs, buf_len - buf_offs,
					  "(L%d%+" PRIdPTR ") ", i+1,
					  start - lxhs[i]);
			buf_offs += nchars;
			continue;
		}
		nchars = snprintf(buf + buf_offs, buf_len - buf_offs,
				  "%s[L%d]> ",
				  osmo_hexdump(start, lxhs[i] - start),
				  i+1);
		if (nchars < 0 || nchars + buf_offs >= buf_len)
			return "ERROR";

		buf_offs += nchars;
		start = lxhs[i];
	}
	nchars = snprintf(buf + buf_offs, buf_len - buf_offs,
			  "%s", osmo_hexdump(start, msg->tail - start));
	if (nchars < 0 || nchars + buf_offs >= buf_len)
		return "ERROR";

	buf_offs += nchars;

	for (i = 0; i < ARRAY_SIZE(lxhs); i++) {
		if (!lxhs[i])
			continue;

		if (lxhs[i] < msg->head || lxhs[i] > msg->head + msg->data_len) {
			nchars = snprintf(buf + buf_offs, buf_len - buf_offs,
					  "(L%d out of range) ", i+1);
		} else if (lxhs[i] <= msg->data + msg->data_len &&
			   lxhs[i] > msg->tail) {
			nchars = snprintf(buf + buf_offs, buf_len - buf_offs,
					  "(L%d=tail%+" PRIdPTR ") ",
					  i+1, lxhs[i] - msg->tail);
		} else
			continue;

		if (nchars < 0 || nchars + buf_offs >= buf_len)
			return "ERROR";
		buf_offs += nchars;
	}

	return buf;
}

/*! Return a (static) buffer containing a hexdump of the msg.
 * \param[in] msg message buffer
 * \returns a pointer to a static char array
 */
const char *msgb_hexdump(const struct msgb *msg)
{
	static char buf[4100];
	return msgb_hexdump_buf(buf, sizeof(buf), msg);
}

/*! Return a dynamically allocated buffer containing a hexdump of the msg
 * \param[in] ctx talloc context from where to allocate the output string
 * \param[in] msg message buffer
 * \returns a pointer to a static char array
 */
char *msgb_hexdump_c(const void *ctx, const struct msgb *msg)
{
	char *buf = talloc_size(ctx, msgb_length(msg)*3 + 100);
	if (!buf)
		return NULL;
	return msgb_hexdump_buf(buf, sizeof(buf), msg);
}

/*! Print a string to the end of message buffer.
 * \param[in] msgb message buffer.
 * \param[in] format format string.
 * \returns 0 on success, -EINVAL on error.
 *
 * The resulting string is printed to the msgb without a trailing nul
 * character. A nul following the data tail may be written as an implementation
 * detail, but a trailing nul is never part of the msgb data in terms of
 * msgb_length().
 *
 * Note: the tailroom must always be one byte longer than the string to be
 * written. The msgb is filled only up to tailroom=1. This is an implementation
 * detail that allows leaving a nul character behind the valid data.
 *
 * In case of error, the msgb remains unchanged, though data may have been
 * written to the (unused) memory after the tail pointer.
 */
int msgb_printf(struct msgb *msgb, const char *format, ...)
{
	va_list args;
	int str_len;
	int rc = 0;

	OSMO_ASSERT(msgb);
	OSMO_ASSERT(format);

	/* Regardless of what we plan to add to the buffer, we must at least
	 * be able to store a string terminator (nullstring) */
	if (msgb_tailroom(msgb) < 1)
		return -EINVAL;

	va_start(args, format);

	str_len =
	    vsnprintf((char *)msgb->tail, msgb_tailroom(msgb), format, args);

	if (str_len >= msgb_tailroom(msgb) || str_len < 0) {
		rc = -EINVAL;
	} else
		msgb_put(msgb, str_len);

	va_end(args);
	return rc;
}

/*! @} */