aboutsummaryrefslogtreecommitdiffstats
path: root/src/tbf_ul.cpp
blob: 3ab71f05b267b5ec0b0f43cf63b9c13a76cc6608 (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
/* Copied from tbf.cpp
 *
 * Copyright (C) 2012 Ivan Klyuchnikov
 * Copyright (C) 2012 Andreas Eversberg <jolly@eversberg.eu>
 * Copyright (C) 2013 by Holger Hans Peter Freyther
 *
 * 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

#include <bts.h>
#include <tbf.h>
#include <rlc.h>
#include <encoding.h>
#include <gprs_rlcmac.h>
#include <gprs_debug.h>
#include <gprs_bssgp_pcu.h>
#include <decoding.h>

extern "C" {
#include <osmocom/core/msgb.h>
#include <osmocom/core/talloc.h>
}

#include <errno.h>
#include <string.h>

/* After receiving these frames, we send ack/nack. */
#define SEND_ACK_AFTER_FRAMES 20

extern void *tall_pcu_ctx;


/*
 * Store received block data in LLC message(s) and forward to SGSN
 * if complete.
 */
int gprs_rlcmac_ul_tbf::assemble_forward_llc(const gprs_rlc_data *_data)
{
	const uint8_t *data = _data->block;
	uint8_t len = _data->len;
	const struct rlc_ul_header *rh = (const struct rlc_ul_header *) data;
	uint8_t e, m;
	struct rlc_li_field *li;
	uint8_t frame_offset[16], offset = 0, chunk;
	int i, frames = 0;

	LOGP(DRLCMACUL, LOGL_DEBUG, "- Assembling frames: (len=%d)\n", len);

	data += 3;
	len -= 3;
	e = rh->e; /* if extended */
	m = 1; /* more frames, that means: the first frame */

	/* Parse frame offsets from length indicator(s), if any. */
	while (1) {
		if (frames == (int)sizeof(frame_offset)) {
			LOGP(DRLCMACUL, LOGL_ERROR, "%s too many frames in "
				"block\n", tbf_name(this));
			return -EINVAL;
		}
		frame_offset[frames++] = offset;
		LOGP(DRLCMACUL, LOGL_DEBUG, "-- Frame %d starts at offset "
			"%d\n", frames, offset);
		if (!len)
			break;
		/* M == 0 and E == 0 is not allowed in this version. */
		if (!m && !e) {
			LOGP(DRLCMACUL, LOGL_NOTICE, "%s UL DATA "
				"ignored, because M='0' and E='0'.\n",
				tbf_name(this));
			return 0;
		}
		/* no more frames in this segment */
		if (e) {
			break;
		}
		/* There is a new frame and an LI that delimits it. */
		if (m) {
			li = (struct rlc_li_field *)data;
			LOGP(DRLCMACUL, LOGL_DEBUG, "-- Delimiter len=%d\n",
				li->li);
			/* Special case: LI == 0
			 * If the last segment would fit precisely into the
			 * rest of the RLC MAC block, there would be no way
			 * to delimit that this segment ends and is not
			 * continued in the next block.
			 * The special LI (0) is used to force the segment to
			 * extend into the next block, so it is delimited there.
			 * This LI must be skipped. Also it is the last LI.
			 */
			if (li->li == 0) {
				data++;
				len--;
				m = 1; /* M is ignored, we know there is more */
				break; /* handle E as '1', so we break! */
			}
			e = li->e;
			m = li->m;
			offset += li->li;
			data++;
			len--;
			continue;
		}
	}
	if (!m) {
		LOGP(DRLCMACUL, LOGL_DEBUG, "- Last frame carries spare "
			"data\n");
	}

	LOGP(DRLCMACUL, LOGL_DEBUG, "- Data length after length fields: %d\n",
		len);
	/* TLLI */
	if (rh->ti) {
		if (len < 4) {
			LOGP(DRLCMACUL, LOGL_NOTICE, "%s UL DATA TLLI out of "
				"frame border\n", tbf_name(this));
			return -EINVAL;
		}
		data += 4;
		len -= 4;
		LOGP(DRLCMACUL, LOGL_DEBUG, "- Length after skipping TLLI: "
			"%d\n", len);
	}

	/* PFI */
	if (rh->pi) {
		LOGP(DRLCMACUL, LOGL_ERROR, "ERROR: PFI not supported, "
			"please disable in SYSTEM INFORMATION\n");
		if (len < 1) {
			LOGP(DRLCMACUL, LOGL_NOTICE, "%s UL DATA PFI out of "
				"frame border\n", tbf_name(this));
			return -EINVAL;
		}
		data++;
		len--;
		LOGP(DRLCMACUL, LOGL_DEBUG, "- Length after skipping PFI: "
			"%d\n", len);
	}

	/* Now we have:
	 * - a list of frames offsets: frame_offset[]
	 * - number of frames: i
	 * - m == 0: Last frame carries spare data (end of TBF).
	 */

	/* Check if last offset would exceed frame. */
	if (offset > len) {
		LOGP(DRLCMACUL, LOGL_NOTICE, "%s UL DATA ignored, "
			"because LI delimits data that exceeds block size.\n",
			tbf_name(this));
		return -EINVAL;
	}

	/* create LLC frames */
	for (i = 0; i < frames; i++) {
		/* last frame ? */
		if (i == frames - 1) {
			/* no more data in last frame */
			if (!m)
				break;
			/* data until end of frame */
			chunk = len - frame_offset[i];
		} else {
			/* data until next frame */
			chunk = frame_offset[i + 1] - frame_offset[i];
		}
		if (!m_llc.fits_in_current_frame(chunk)) {
			LOGP(DRLCMACUL, LOGL_NOTICE, "%s LLC frame exceeds "
				"maximum size %u.\n", tbf_name(this),
				m_llc.remaining_space());
			chunk = m_llc.remaining_space();
		}
		m_llc.append_frame(data + frame_offset[i], chunk);
		m_llc.consume(chunk);
		/* not last frame. */
		if (i != frames - 1) {
			/* send frame to SGSN */
			LOGP(DRLCMACUL, LOGL_INFO, "%s complete UL frame len=%d\n",
				tbf_name(this) , m_llc.frame_length());
			snd_ul_ud();
			m_llc.reset();
		/* also check if CV==0, because the frame may fill up the
		 * block precisely, then it is also complete. normally the
		 * frame would be extended into the next block with a 0-length
		 * delimiter added to this block. */
		} else if (rh->cv == 0) {
			/* send frame to SGSN */
			LOGP(DRLCMACUL, LOGL_INFO, "%s complete UL frame "
				"that fits precisely in last block: "
				"len=%d\n", tbf_name(this), m_llc.frame_length());
			snd_ul_ud();
			m_llc.reset();
		}
	}

	return 0;
}


struct msgb *gprs_rlcmac_ul_tbf::create_ul_ack(uint32_t fn)
{
	int final = (state_is(GPRS_RLCMAC_FINISHED));
	struct msgb *msg;

	if (final) {
		if (poll_state != GPRS_RLCMAC_POLL_NONE) {
			LOGP(DRLCMACUL, LOGL_DEBUG, "Polling is already "
				"sheduled for %s, so we must wait for "
				"final uplink ack...\n", tbf_name(this));
			return NULL;
		}
		if (bts->sba()->find(trx->trx_no, control_ts, (fn + 13) % 2715648)) {
			LOGP(DRLCMACUL, LOGL_DEBUG, "Polling is already "
				"scheduled for single block allocation...\n");
			return NULL;
		}
	}

	msg = msgb_alloc(23, "rlcmac_ul_ack");
	if (!msg)
		return NULL;
	bitvec *ack_vec = bitvec_alloc(23);
	if (!ack_vec) {
		msgb_free(msg);
		return NULL;
	}
	bitvec_unhex(ack_vec,
		"2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b2b");
	RlcMacDownlink_t * mac_control_block = (RlcMacDownlink_t *)talloc_zero(tall_pcu_ctx, RlcMacDownlink_t);
	Encoding::write_packet_uplink_ack(bts_data(), mac_control_block, this, final);
	encode_gsm_rlcmac_downlink(ack_vec, mac_control_block);
	bitvec_pack(ack_vec, msgb_put(msg, 23));
	bitvec_free(ack_vec);
	talloc_free(mac_control_block);

	/* now we must set this flag, so we are allowed to assign downlink
	 * TBF on PACCH. it is only allowed when TLLI is acknowledged. */
	m_contention_resolution_done = 1;

	if (final) {
		poll_state = GPRS_RLCMAC_POLL_SCHED;
		poll_fn = (fn + 13) % 2715648;
		/* waiting for final acknowledge */
		ul_ack_state = GPRS_RLCMAC_UL_ACK_WAIT_ACK;
		m_final_ack_sent = 1;
	} else
		ul_ack_state = GPRS_RLCMAC_UL_ACK_NONE;

	return msg;
}

int gprs_rlcmac_ul_tbf::rcv_data_block_acknowledged(const uint8_t *data, size_t len, int8_t rssi)
{
	struct rlc_ul_header *rh = (struct rlc_ul_header *)data;
	int rc;

	const uint16_t mod_sns = m_window.mod_sns();
	const uint16_t ws = m_window.ws();

	this->state_flags |= (1 << GPRS_RLCMAC_FLAG_UL_DATA);

	LOGP(DRLCMACUL, LOGL_DEBUG, "UL DATA TFI=%d received (V(Q)=%d .. "
		"V(R)=%d)\n", rh->tfi, this->m_window.v_q(),
		this->m_window.v_r());

	/* process RSSI */
	gprs_rlcmac_rssi(this, rssi);

	/* get TLLI */
	if (!this->is_tlli_valid()) {
		if (!extract_tlli(data, len))
			return 0;
	/* already have TLLI, but we stille get another one */
	} else if (rh->ti) {
		uint32_t tlli;
		rc = Decoding::tlli_from_ul_data(data, len, &tlli);
		if (rc) {
			LOGP(DRLCMACUL, LOGL_NOTICE, "Failed to decode TLLI "
				"of UL DATA TFI=%d.\n", rh->tfi);
			return 0;
		}
		if (tlli != this->tlli()) {
			LOGP(DRLCMACUL, LOGL_NOTICE, "TLLI mismatch on UL "
				"DATA TFI=%d. (Ignoring due to contention "
				"resolution)\n", rh->tfi);
			return 0;
		}
	}

	/* restart T3169 */
	tbf_timer_start(this, 3169, bts_data()->t3169, 0);

	/* Increment RX-counter */
	this->m_rx_counter++;

	if (!m_window.is_in_window(rh->bsn)) {
		LOGP(DRLCMACUL, LOGL_DEBUG, "- BSN %d out of window "
			"%d..%d (it's normal)\n", rh->bsn,
			m_window.v_q(),
			(m_window.v_q() + ws - 1) & mod_sns);
		maybe_schedule_uplink_acknack(rh);
		return 0;
	}

	/* Write block to buffer and set receive state array. */
	m_rlc.block(rh->bsn)->put_data(data, len);
	LOGP(DRLCMACUL, LOGL_DEBUG, "- BSN %d storing in window (%d..%d)\n",
		rh->bsn, m_window.v_q(),
		(m_window.v_q() + ws - 1) & mod_sns);

	/* Raise V(Q) if possible, and retrieve LLC frames from blocks.
	 * This is looped until there is a gap (non received block) or
	 * the window is empty.*/
	const uint16_t v_q_beg = m_window.v_q();

	const uint16_t count = m_window.receive_bsn(rh->bsn);

	/* Retrieve LLC frames from blocks that are ready */
	for (uint16_t i = 0; i < count; ++i) {
		uint16_t index = (v_q_beg + i) & mod_sns;
		assemble_forward_llc(m_rlc.block(index));
	}

	/* Check CV of last frame in buffer */
	if (this->state_is(GPRS_RLCMAC_FLOW) /* still in flow state */
	 && this->m_window.v_q() == this->m_window.v_r()) { /* if complete */
		struct rlc_ul_header *last_rh = (struct rlc_ul_header *)
			m_rlc.block((m_window.v_r() - 1) & mod_sns)->block;
		LOGP(DRLCMACUL, LOGL_DEBUG, "- No gaps in received block, "
			"last block: BSN=%d CV=%d\n", last_rh->bsn,
			last_rh->cv);
		if (last_rh->cv == 0) {
			LOGP(DRLCMACUL, LOGL_DEBUG, "- Finished with UL "
				"TBF\n");
			set_state(GPRS_RLCMAC_FINISHED);
			/* Reset N3103 counter. */
			this->m_n3103 = 0;
		}
	}

	/* If TLLI is included or if we received half of the window, we send
	 * an ack/nack */
	maybe_schedule_uplink_acknack(rh);

	return 0;
}

void gprs_rlcmac_ul_tbf::maybe_schedule_uplink_acknack(const rlc_ul_header *rh)
{
	if (rh->si || rh->ti || state_is(GPRS_RLCMAC_FINISHED)
	 || (m_rx_counter % SEND_ACK_AFTER_FRAMES) == 0) {
		if (rh->si) {
			LOGP(DRLCMACUL, LOGL_NOTICE, "- Scheduling Ack/Nack, "
				"because MS is stalled.\n");
		}
		if (rh->ti) {
			LOGP(DRLCMACUL, LOGL_DEBUG, "- Scheduling Ack/Nack, "
				"because TLLI is included.\n");
		}
		if (state_is(GPRS_RLCMAC_FINISHED)) {
			LOGP(DRLCMACUL, LOGL_DEBUG, "- Scheduling Ack/Nack, "
				"because last block has CV==0.\n");
		}
		if ((m_rx_counter % SEND_ACK_AFTER_FRAMES) == 0) {
			LOGP(DRLCMACUL, LOGL_DEBUG, "- Scheduling Ack/Nack, "
				"because %d frames received.\n",
				SEND_ACK_AFTER_FRAMES);
		}
		if (ul_ack_state == GPRS_RLCMAC_UL_ACK_NONE) {
			/* trigger sending at next RTS */
			ul_ack_state = GPRS_RLCMAC_UL_ACK_SEND_ACK;
		} else {
			/* already triggered */
			LOGP(DRLCMACUL, LOGL_DEBUG, "-  Sending Ack/Nack is "
				"already triggered, don't schedule!\n");
		}
	}
}

/* Send Uplink unit-data to SGSN. */
int gprs_rlcmac_ul_tbf::snd_ul_ud()
{
	uint8_t qos_profile[3];
	struct msgb *llc_pdu;
	unsigned msg_len = NS_HDR_LEN + BSSGP_HDR_LEN + m_llc.frame_length();
	struct bssgp_bvc_ctx *bctx = gprs_bssgp_pcu_current_bctx();

	LOGP(DBSSGP, LOGL_INFO, "LLC [PCU -> SGSN] %s len=%d\n", tbf_name(this), m_llc.frame_length());
	if (!bctx) {
		LOGP(DBSSGP, LOGL_ERROR, "No bctx\n");
		m_llc.reset_frame_space();
		return -EIO;
	}
	
	llc_pdu = msgb_alloc_headroom(msg_len, msg_len,"llc_pdu");
	uint8_t *buf = msgb_push(llc_pdu, TL16V_GROSS_LEN(sizeof(uint8_t)*m_llc.frame_length()));
	tl16v_put(buf, BSSGP_IE_LLC_PDU, sizeof(uint8_t)*m_llc.frame_length(), m_llc.frame);
	qos_profile[0] = QOS_PROFILE >> 16;
	qos_profile[1] = QOS_PROFILE >> 8;
	qos_profile[2] = QOS_PROFILE;
	bssgp_tx_ul_ud(bctx, tlli(), qos_profile, llc_pdu);

	m_llc.reset_frame_space();
	return 0;
}