summaryrefslogtreecommitdiffstats
path: root/include/osmocom/core/msgb.h
blob: 33e8081f848c32d06f798a764d54b21000ee6837 (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
#ifndef _MSGB_H
#define _MSGB_H

/* (C) 2008 by Harald Welte <laforge@gnumonks.org>
 * All Rights Reserved
 *
 * 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.
 *
 */

#include <stdint.h>
#include <osmocom/core/linuxlist.h>
#include <osmocom/core/utils.h>

/*! \defgroup msgb Message buffers
 *  @{
 */

/*! \file msgb.h
 *  \brief Osmocom message buffers
 * The Osmocom message buffers are modelled after the 'struct skb'
 * inside the Linux kernel network stack.  As they exist in userspace,
 * they are much simplified.  However, terminology such as headroom,
 * tailroom, push/pull/put etc. remains the same.
 */

#define MSGB_DEBUG

/*! \brief Osmocom message buffer */
struct msgb {
	struct llist_head list; /*!< \brief linked list header */


	/* Part of which TRX logical channel we were received / transmitted */
	/* FIXME: move them into the control buffer */
	union {
		void *dst; /*!< \brief reference of origin/destination */
		struct gsm_bts_trx *trx;
	};
	struct gsm_lchan *lchan; /*!< \brief logical channel */

	unsigned char *l1h; /*!< \brief pointer to Layer1 header (if any) */
	unsigned char *l2h; /*!< \brief pointer to A-bis layer 2 header: OML, RSL(RLL), NS */
	unsigned char *l3h; /*!< \brief pointer to Layer 3 header. For OML: FOM; RSL: 04.08; GPRS: BSSGP */
	unsigned char *l4h; /*!< \brief pointer to layer 4 header */

	unsigned long cb[5]; /*!< \brief control buffer */

	uint16_t data_len;   /*!< \brief length of underlying data array */
	uint16_t len;	     /*!< \brief length of bytes used in msgb */

	unsigned char *head;	/*!< \brief start of underlying memory buffer */
	unsigned char *tail;	/*!< \brief end of message in buffer */
	unsigned char *data;	/*!< \brief start of message in buffer */
	unsigned char _data[0]; /*!< \brief optional immediate data array */
};

extern struct msgb *msgb_alloc(uint16_t size, const char *name);
extern void msgb_free(struct msgb *m);
extern void msgb_enqueue(struct llist_head *queue, struct msgb *msg);
extern struct msgb *msgb_dequeue(struct llist_head *queue);
extern void msgb_reset(struct msgb *m);
uint16_t msgb_length(const struct msgb *msg);
extern const char *msgb_hexdump(const struct msgb *msg);

#ifdef MSGB_DEBUG
#include <osmocom/core/panic.h>
#define MSGB_ABORT(msg, fmt, args ...) do {		\
	osmo_panic("msgb(%p): " fmt, msg, ## args);	\
	} while(0)
#else
#define MSGB_ABORT(msg, fmt, args ...)
#endif

/*! \brief obtain L1 header of msgb */
#define msgb_l1(m)	((void *)(m->l1h))
/*! \brief obtain L2 header of msgb */
#define msgb_l2(m)	((void *)(m->l2h))
/*! \brief obtain L3 header of msgb */
#define msgb_l3(m)	((void *)(m->l3h))
/*! \brief obtain SMS header of msgb */
#define msgb_sms(m)	((void *)(m->l4h))

/*! \brief determine length of L1 message
 *  \param[in] msgb message buffer
 *  \returns size of L1 message in bytes
 *
 * This function computes the number of bytes between the tail of the
 * message and the layer 1 header.
 */
static inline unsigned int msgb_l1len(const struct msgb *msgb)
{
	return msgb->tail - (uint8_t *)msgb_l1(msgb);
}

/*! \brief determine length of L2 message
 *  \param[in] msgb message buffer
 *  \returns size of L2 message in bytes
 *
 * This function computes the number of bytes between the tail of the
 * message and the layer 2 header.
 */
static inline unsigned int msgb_l2len(const struct msgb *msgb)
{
	return msgb->tail - (uint8_t *)msgb_l2(msgb);
}

/*! \brief determine length of L3 message
 *  \param[in] msgb message buffer
 *  \returns size of L3 message in bytes
 *
 * This function computes the number of bytes between the tail of the
 * message and the layer 3 header.
 */
static inline unsigned int msgb_l3len(const struct msgb *msgb)
{
	return msgb->tail - (uint8_t *)msgb_l3(msgb);
}

/*! \brief determine the length of the header
 *  \param[in] msgb message buffer
 *  \returns number of bytes between start of buffer and start of msg
 *
 * This function computes the length difference between the underlying
 * data buffer and the used section of the \a msgb.
 */
static inline unsigned int msgb_headlen(const struct msgb *msgb)
{
	return msgb->len - msgb->data_len;
}

/*! \brief determine how much tail room is left in msgb
 *  \param[in] msgb message buffer
 *  \returns number of bytes remaining at end of msgb
 *
 * This function computes the amount of octets left in the underlying
 * data buffer after the end of the message.
 */
static inline int msgb_tailroom(const struct msgb *msgb)
{
	return (msgb->head + msgb->data_len) - msgb->tail;
}

/*! \brief determine the amount of headroom in msgb
 *  \param[in] msgb message buffer
 *  \returns number of bytes left ahead of message start in msgb
 *
 * This function computes the amount of bytes left in the underlying
 * data buffer before the start of the actual message.
 */
static inline int msgb_headroom(const struct msgb *msgb)
{
	return (msgb->data - msgb->head);
}

/*! \brief append data to end of message buffer
 *  \param[in] msgb message buffer
 *  \param[in] len number of bytes to append to message
 *  \returns pointer to start of newly-appended data
 *
 * This function will move the \a tail pointer of the message buffer \a
 * len bytes further, thus enlarging the message by \a len bytes.
 *
 * The return value is a pointer to start of the newly added section at
 * the end of the message and can be used for actually filling/copying
 * data into it.
 */
static inline unsigned char *msgb_put(struct msgb *msgb, unsigned int len)
{
	unsigned char *tmp = msgb->tail;
	if (msgb_tailroom(msgb) < (int) len)
		MSGB_ABORT(msgb, "Not enough tailroom msgb_push (%u < %u)\n",
			   msgb_tailroom(msgb), len);
	msgb->tail += len;
	msgb->len += len;
	return tmp;
}

/*! \brief append a uint8 value to the end of the message
 *  \param[in] msgb message buffer
 *  \param[in] word unsigned 8bit byte to be appended
 */
static inline void msgb_put_u8(struct msgb *msgb, uint8_t word)
{
	uint8_t *space = msgb_put(msgb, 1);
	space[0] = word & 0xFF;
}

/*! \brief append a uint16 value to the end of the message
 *  \param[in] msgb message buffer
 *  \param[in] word unsigned 16bit byte to be appended
 */
static inline void msgb_put_u16(struct msgb *msgb, uint16_t word)
{
	uint8_t *space = msgb_put(msgb, 2);
	space[0] = word >> 8 & 0xFF;
	space[1] = word & 0xFF;
}

/*! \brief append a uint32 value to the end of the message
 *  \param[in] msgb message buffer
 *  \param[in] word unsigned 32bit byte to be appended
 */
static inline void msgb_put_u32(struct msgb *msgb, uint32_t word)
{
	uint8_t *space = msgb_put(msgb, 4);
	space[0] = word >> 24 & 0xFF;
	space[1] = word >> 16 & 0xFF;
	space[2] = word >> 8 & 0xFF;
	space[3] = word & 0xFF;
}

/*! \brief remove data from end of message
 *  \param[in] msgb message buffer
 *  \param[in] len number of bytes to remove from end
 */
static inline unsigned char *msgb_get(struct msgb *msgb, unsigned int len)
{
	unsigned char *tmp = msgb->data - len;
	if (msgb_length(msgb) < len)
		MSGB_ABORT(msgb, "msgb too small to get %u (len %u)\n",
			   len, msgb_length(msgb));
	msgb->tail -= len;
	msgb->len -= len;
	return tmp;
}
/*! \brief remove uint8 from end of message
 *  \param[in] msgb message buffer
 *  \returns 8bit value taken from end of msgb
 */
static inline uint8_t msgb_get_u8(struct msgb *msgb)
{
	uint8_t *space = msgb_get(msgb, 1);
	return space[0];
}
/*! \brief remove uint16 from end of message
 *  \param[in] msgb message buffer
 *  \returns 16bit value taken from end of msgb
 */
static inline uint16_t msgb_get_u16(struct msgb *msgb)
{
	uint8_t *space = msgb_get(msgb, 2);
	return space[0] << 8 | space[1];
}
/*! \brief remove uint32 from end of message
 *  \param[in] msgb message buffer
 *  \returns 32bit value taken from end of msgb
 */
static inline uint32_t msgb_get_u32(struct msgb *msgb)
{
	uint8_t *space = msgb_get(msgb, 4);
	return space[0] << 24 | space[1] << 16 | space[2] << 8 | space[3];
}

/*! \brief prepend (push) some data to start of message
 *  \param[in] msgb message buffer
 *  \param[in] len number of bytes to pre-pend
 *  \returns pointer to newly added portion at start of \a msgb
 *
 * This function moves the \a data pointer of the \ref msgb further
 * to the front (by \a len bytes), thereby enlarging the message by \a
 * len bytes.
 *
 * The return value is a pointer to the newly added section in the
 * beginning of the message.  It can be used to fill/copy data into it.
 */
static inline unsigned char *msgb_push(struct msgb *msgb, unsigned int len)
{
	if (msgb_headroom(msgb) < (int) len)
		MSGB_ABORT(msgb, "Not enough headroom msgb_push (%u < %u)\n",
			   msgb_headroom(msgb), len);
	msgb->data -= len;
	msgb->len += len;
	return msgb->data;
}
/*! \brief remove (pull) a header from the front of the message buffer
 *  \param[in] msgb message buffer
 *  \param[in] len number of octets to be pulled
 *  \returns pointer to new start of msgb
 *
 * This function moves the \a data pointer of the \ref msgb further back
 * in the message, thereby shrinking the size of the message by \a len
 * bytes.
 */
static inline unsigned char *msgb_pull(struct msgb *msgb, unsigned int len)
{
	msgb->len -= len;
	return msgb->data += len;
}

/*! \brief remove (pull) all headers in front of l3h from the message buffer.
 *  \param[in] msgb message buffer with a valid l3h
 *  \returns pointer to new start of msgb (l3h)
 *
 * This function moves the \a data pointer of the \ref msgb further back
 * in the message, thereby shrinking the size of the message.
 * l1h and l2h will be cleared.
 */
static inline unsigned char *msgb_pull_to_l3(struct msgb *msg)
{
	unsigned char *ret = msgb_pull(msg, msg->l3h - msg->data);
	msg->l1h = msg->l2h = NULL;
	return ret;
}

/*! \brief remove uint8 from front of message
 *  \param[in] msgb message buffer
 *  \returns 8bit value taken from end of msgb
 */
static inline uint8_t msgb_pull_u8(struct msgb *msgb)
{
	uint8_t *space = msgb_pull(msgb, 1) - 1;
	return space[0];
}
/*! \brief remove uint16 from front of message
 *  \param[in] msgb message buffer
 *  \returns 16bit value taken from end of msgb
 */
static inline uint16_t msgb_pull_u16(struct msgb *msgb)
{
	uint8_t *space = msgb_pull(msgb, 2) - 2;
	return space[0] << 8 | space[1];
}
/*! \brief remove uint32 from front of message
 *  \param[in] msgb message buffer
 *  \returns 32bit value taken from end of msgb
 */
static inline uint32_t msgb_pull_u32(struct msgb *msgb)
{
	uint8_t *space = msgb_pull(msgb, 4) - 4;
	return space[0] << 24 | space[1] << 16 | space[2] << 8 | space[3];
}

/*! \brief Increase headroom of empty msgb, reducing the tailroom
 *  \param[in] msg message buffer
 *  \param[in] len amount of extra octets to be reserved as headroom
 *
 * This function reserves some memory at the beginning of the underlying
 * data buffer.  The idea is to reserve space in case further headers
 * have to be pushed to the \ref msgb during further processing.
 *
 * Calling this function leads to undefined reusults if it is called on
 * a non-empty \ref msgb.
 */
static inline void msgb_reserve(struct msgb *msg, int len)
{
	msg->data += len;
	msg->tail += len;
}

/*! \brief Trim the msgb to a given absolute length
 *  \param[in] msg message buffer
 *  \param[in] len new total length of buffer
 *  \returns 0 in case of success, negative in case of error
 */
static inline int msgb_trim(struct msgb *msg, int len)
{
	if (len > msg->data_len)
		return -1;

	msg->len = len;
	msg->tail = msg->data + len;

	return 0;
}

/*! \brief Trim the msgb to a given layer3 length
 *  \param[in] msg message buffer
 *  \param[in] l3len new layer3 length
 *  \returns 0 in case of success, negative in case of error
 */
static inline int msgb_l3trim(struct msgb *msg, int l3len)
{
	return msgb_trim(msg, (msg->l3h - msg->data) + l3len);
}

/*! \brief Allocate message buffer with specified headroom
 *  \param[in] size size in bytes, including headroom
 *  \param[in] headroom headroom in bytes
 *  \param[in] name human-readable name
 *  \returns allocated message buffer with specified headroom
 *
 * This function is a convenience wrapper around \ref msgb_alloc
 * followed by \ref msgb_reserve in order to create a new \ref msgb with
 * user-specified amount of headroom.
 */
static inline struct msgb *msgb_alloc_headroom(int size, int headroom,
						const char *name)
{
	osmo_static_assert(size > headroom, headroom_bigger);

	struct msgb *msg = msgb_alloc(size, name);
	if (msg)
		msgb_reserve(msg, headroom);
	return msg;
}

/* non inline functions to ease binding */

uint8_t *msgb_data(const struct msgb *msg);
void msgb_set_talloc_ctx(void *ctx);

/*! @} */

#endif /* _MSGB_H */