1 /* GSM LAPDm (TS 04.06) implementation */
3 /* (C) 2010 by Harald Welte <laforge@gnumonks.org>
4 * (C) 2010 by Andreas Eversberg <jolly@eversberg.eu>
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
18 * You should have received a copy of the GNU General Public License along
19 * with this program; if not, write to the Free Software Foundation, Inc.,
20 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
24 /* Notes on Buffering: rcv_buffer, tx_queue, tx_hist, send_buffer, send_queue
26 * RX data is stored in the rcv_buffer (pointer). If the message is complete, it
27 * is removed from rcv_buffer pointer and forwarded to L3. If the RX data is
28 * received while there is an incomplete rcv_buffer, it is appended to it.
30 * TX data is stored in the send_queue first. When transmitting a frame,
31 * the first message in the send_queue is moved to the send_buffer. There it
32 * resides until all fragments are acknowledged. Fragments to be sent by I
33 * frames are stored in the tx_hist buffer for resend, if required. Also the
34 * current fragment is copied into the tx_queue. There it resides until it is
35 * forwarded to layer 1.
37 * In case we have SAPI 0, we only have a window size of 1, so the unack-
38 * nowledged message resides always in the send_buffer. In case of a suspend,
39 * it can be written back to the first position of the send_queue.
41 * The layer 1 normally sends a PH-READY-TO-SEND. But because we use
42 * asynchronous transfer between layer 1 and layer 2 (serial link), we must
43 * send a frame before layer 1 reaches the right timeslot to send it. So we
44 * move the tx_queue to layer 1 when there is not already a pending frame, and
45 * wait until acknowledge after the frame has been sent. If we receive an
46 * acknowledge, we can send the next frame from the buffer, if any.
48 * The moving of tx_queue to layer 1 may also trigger T200, if desired. Also it
49 * will trigger next I frame, if possible.
57 #include <arpa/inet.h>
59 #include <osmocore/logging.h>
60 #include <osmocore/timer.h>
61 #include <osmocore/msgb.h>
62 #include <osmocore/tlv.h>
63 #include <osmocore/utils.h>
64 #include <osmocore/rsl.h>
65 #include <osmocore/protocol/gsm_04_08.h>
66 #include <osmocore/protocol/gsm_08_58.h>
68 #include <osmocom/bb/common/osmocom_data.h>
69 #include <osmocom/bb/common/l1ctl.h>
70 #include <osmocom/bb/common/lapdm.h>
71 #include <osmocom/bb/common/logging.h>
73 #include <l1ctl_proto.h>
75 /* TS 04.06 Figure 4 / Section 3.2 */
76 #define LAPDm_LPD_NORMAL 0
77 #define LAPDm_LPD_SMSCB 1
78 #define LAPDm_SAPI_NORMAL 0
79 #define LAPDm_SAPI_SMS 3
80 #define LAPDm_ADDR(lpd, sapi, cr) ((((lpd) & 0x3) << 5) | (((sapi) & 0x7) << 2) | (((cr) & 0x1) << 1) | 0x1)
82 #define LAPDm_ADDR_SAPI(addr) (((addr) >> 2) & 0x7)
83 #define LAPDm_ADDR_CR(addr) (((addr) >> 1) & 0x1)
84 #define LAPDm_ADDR_EA(addr) ((addr) & 0x1)
86 /* TS 04.06 Table 3 / Section 3.4.3 */
87 #define LAPDm_CTRL_I(nr, ns, p) ((((nr) & 0x7) << 5) | (((p) & 0x1) << 4) | (((ns) & 0x7) << 1))
88 #define LAPDm_CTRL_S(nr, s, p) ((((nr) & 0x7) << 5) | (((p) & 0x1) << 4) | (((s) & 0x3) << 2) | 0x1)
89 #define LAPDm_CTRL_U(u, p) ((((u) & 0x1c) << (5-2)) | (((p) & 0x1) << 4) | (((u) & 0x3) << 2) | 0x3)
91 #define LAPDm_CTRL_is_I(ctrl) (((ctrl) & 0x1) == 0)
92 #define LAPDm_CTRL_is_S(ctrl) (((ctrl) & 0x3) == 1)
93 #define LAPDm_CTRL_is_U(ctrl) (((ctrl) & 0x3) == 3)
95 #define LAPDm_CTRL_U_BITS(ctrl) ((((ctrl) & 0xC) >> 2) | ((ctrl) & 0xE0) >> 3)
96 #define LAPDm_CTRL_PF_BIT(ctrl) (((ctrl) >> 4) & 0x1)
98 #define LAPDm_CTRL_S_BITS(ctrl) (((ctrl) & 0xC) >> 2)
100 #define LAPDm_CTRL_I_Ns(ctrl) (((ctrl) & 0xE) >> 1)
101 #define LAPDm_CTRL_Nr(ctrl) (((ctrl) & 0xE0) >> 5)
103 /* TS 04.06 Table 4 / Section 3.8.1 */
104 #define LAPDm_U_SABM 0x7
105 #define LAPDm_U_DM 0x3
106 #define LAPDm_U_UI 0x0
107 #define LAPDm_U_DISC 0x8
108 #define LAPDm_U_UA 0xC
110 #define LAPDm_S_RR 0x0
111 #define LAPDm_S_RNR 0x1
112 #define LAPDm_S_REJ 0x2
114 #define LAPDm_LEN(len) ((len << 2) | 0x1)
115 #define LAPDm_MORE 0x2
117 /* TS 04.06 Section 5.8.3 */
118 #define N201_AB_SACCH 18
119 #define N201_AB_SDCCH 20
120 #define N201_AB_FACCH 20
122 #define N201_Bter_SACCH 21
123 #define N201_Bter_SDCCH 23
124 #define N201_Bter_FACCH 23
127 /* 5.8.2.1 N200 during establish and release */
128 #define N200_EST_REL 5
129 /* 5.8.2.1 N200 during timer recovery state */
130 #define N200_TR_SACCH 5
131 #define N200_TR_SDCCH 23
132 #define N200_TR_FACCH_FR 34
133 #define N200_TR_EFACCH_FR 48
134 #define N200_TR_FACCH_HR 29
135 /* FIXME: this depends on chan type */
136 #define N200 N200_TR_SACCH
138 #define CR_MS2BS_CMD 0
139 #define CR_MS2BS_RESP 1
140 #define CR_BS2MS_CMD 1
141 #define CR_BS2MS_RESP 0
143 /* Set T200 to 1 Second (OpenBTS uses 900ms) */
146 /* k value for each SAPI */
147 static uint8_t k_sapi[] = {1, 1, 1, 1, 1, 1, 1, 1};
157 static void lapdm_t200_cb(void *data);
158 static int rslms_send_i(struct lapdm_msg_ctx *mctx);
160 /* UTILITY FUNCTIONS */
162 static inline uint8_t inc_mod8(uint8_t x)
167 static inline uint8_t add_mod8(uint8_t x, uint8_t y)
172 static inline uint8_t sub_mod8(uint8_t x, uint8_t y)
174 return (x - y) & 7; /* handle negative results correctly */
177 static void lapdm_dl_init(struct lapdm_datalink *dl,
178 struct lapdm_entity *entity)
180 memset(dl, 0, sizeof(*dl));
181 INIT_LLIST_HEAD(&dl->send_queue);
182 INIT_LLIST_HEAD(&dl->tx_queue);
183 dl->state = LAPDm_STATE_IDLE;
185 dl->t200.cb = &lapdm_t200_cb;
189 void lapdm_init(struct lapdm_entity *le, struct osmocom_ms *ms)
193 for (i = 0; i < ARRAY_SIZE(le->datalink); i++)
194 lapdm_dl_init(&le->datalink[i], le);
199 static void lapdm_dl_flush_send(struct lapdm_datalink *dl)
203 /* Flush send-queue */
204 while ((msg = msgb_dequeue(&dl->send_queue)))
207 /* Clear send-buffer */
208 if (dl->send_buffer) {
209 msgb_free(dl->send_buffer);
210 dl->send_buffer = NULL;
214 static void lapdm_dl_flush_tx(struct lapdm_datalink *dl)
219 while ((msg = msgb_dequeue(&dl->tx_queue)))
221 for (i = 0; i < 8; i++)
222 dl->tx_length[i] = 0;
225 void lapdm_exit(struct lapdm_entity *le)
228 struct lapdm_datalink *dl;
230 for (i = 0; i < ARRAY_SIZE(le->datalink); i++) {
231 dl = &le->datalink[i];
232 lapdm_dl_flush_tx(dl);
233 lapdm_dl_flush_send(dl);
235 msgb_free(dl->rcv_buffer);
239 static void lapdm_dl_newstate(struct lapdm_datalink *dl, uint32_t state)
241 LOGP(DLAPDM, LOGL_INFO, "new state %s -> %s\n",
242 lapdm_state_names[dl->state], lapdm_state_names[state]);
247 static struct lapdm_datalink *datalink_for_sapi(struct lapdm_entity *le, uint8_t sapi)
250 case LAPDm_SAPI_NORMAL:
251 return &le->datalink[0];
253 return &le->datalink[1];
259 /* remove the L2 header from a MSGB */
260 static inline unsigned char *msgb_pull_l2h(struct msgb *msg)
262 unsigned char *ret = msgb_pull(msg, msg->l3h - msg->l2h);
267 /* Append padding (if required) */
268 static void lapdm_pad_msgb(struct msgb *msg, uint8_t n201)
270 int pad_len = n201 - msgb_l2len(msg);
274 LOGP(DLAPDM, LOGL_ERROR,
275 "cannot pad message that is already too big!\n");
279 data = msgb_put(msg, pad_len);
280 memset(data, 0x2B, pad_len);
283 /* write a frame into the tx queue */
284 static int tx_ph_data_enqueue(struct lapdm_datalink *dl, struct msgb *msg,
285 uint8_t chan_nr, uint8_t link_id, uint8_t n201)
287 struct lapdm_entity *le = dl->entity;
288 struct osmocom_ms *ms = le->ms;
290 /* if there is a pending message, queue it */
291 if (le->tx_pending) {
292 *msgb_push(msg, 1) = n201;
293 *msgb_push(msg, 1) = link_id;
294 *msgb_push(msg, 1) = chan_nr;
295 msgb_enqueue(&dl->tx_queue, msg);
299 /* send the frame now */
300 le->tx_pending = 0; /* disabled flow control */
301 lapdm_pad_msgb(msg, n201);
302 return l1ctl_tx_data_req(ms, msg, chan_nr, link_id);
305 /* get next frame from the tx queue. because the ms has multiple datalinks,
306 * each datalink's queue is read round-robin.
308 int l2_ph_data_conf(struct msgb *msg, struct lapdm_entity *le)
310 struct osmocom_ms *ms = le->ms;
311 struct lapdm_datalink *dl;
312 int last = le->last_tx_dequeue;
313 int i = last, n = ARRAY_SIZE(le->datalink);
314 uint8_t chan_nr, link_id, n201;
316 /* we may send again */
319 /* free confirm message */
322 /* round-robin dequeue */
326 dl = &le->datalink[i];
327 if ((msg = msgb_dequeue(&dl->tx_queue)))
331 /* no message in all queues */
335 /* Pull chan_nr and link_id */
336 chan_nr = *msg->data;
338 link_id = *msg->data;
343 /* Set last dequeue position */
344 le->last_tx_dequeue = i;
346 /* Pad the frame, we can transmit now */
348 lapdm_pad_msgb(msg, n201);
349 return l1ctl_tx_data_req(ms, msg, chan_nr, link_id);
352 /* Create RSLms various RSLms messages */
353 static int send_rslms_rll_l3(uint8_t msg_type, struct lapdm_msg_ctx *mctx,
356 /* Add the RSL + RLL header */
357 rsl_rll_push_l3(msg, msg_type, mctx->chan_nr, mctx->link_id, 1);
359 /* send off the RSLms message to L3 */
360 return rslms_sendmsg(msg, mctx->dl->entity->ms);
363 /* Take a B4 format message from L1 and create RSLms UNIT DATA IND */
364 static int send_rslms_rll_l3_ui(struct lapdm_msg_ctx *mctx, struct msgb *msg)
366 uint8_t l3_len = msg->tail - (uint8_t *)msgb_l3(msg);
367 struct abis_rsl_rll_hdr *rllh;
369 /* Add the RSL + RLL header */
370 msgb_tv16_push(msg, RSL_IE_L3_INFO, l3_len);
371 msgb_push(msg, 2 + 2);
372 rsl_rll_push_hdr(msg, RSL_MT_UNIT_DATA_IND, mctx->chan_nr,
374 rllh = (struct abis_rsl_rll_hdr *)msgb_l2(msg);
376 rllh->data[0] = RSL_IE_ACCESS_DELAY;
377 rllh->data[1] = mctx->ta_ind;
379 rllh->data[2] = RSL_IE_MS_POWER;
380 rllh->data[3] = mctx->tx_power_ind;
382 return rslms_sendmsg(msg, mctx->dl->entity->ms);
385 static int send_rll_simple(uint8_t msg_type, struct lapdm_msg_ctx *mctx)
389 msg = rsl_rll_simple(msg_type, mctx->chan_nr, mctx->link_id, 1);
391 /* send off the RSLms message to L3 */
392 return rslms_sendmsg(msg, mctx->dl->entity->ms);
395 static int rsl_rll_error(uint8_t cause, struct lapdm_msg_ctx *mctx)
400 LOGP(DLAPDM, LOGL_NOTICE, "sending MDL-ERROR-IND %d\n", cause);
401 msg = rsl_rll_simple(RSL_MT_ERROR_IND, mctx->chan_nr, mctx->link_id, 1);
402 msg->l2h = msgb_put(msg, sizeof(struct abis_rsl_rll_hdr) + 3);
403 tlv = msg->l2h + sizeof(struct abis_rsl_rll_hdr);
404 tlv[0] = RSL_IE_RLM_CAUSE;
407 return rslms_sendmsg(msg, mctx->dl->entity->ms);
410 static int check_length_ind(struct lapdm_msg_ctx *mctx, uint8_t length_ind)
412 if (!(length_ind & 0x01)) {
413 /* G.4.1 If the EL bit is set to "0", an MDL-ERROR-INDICATION
414 * primitive with cause "frame not implemented" is sent to the
415 * mobile management entity. */
416 LOGP(DLAPDM, LOGL_NOTICE,
417 "we don't support multi-octet length\n");
418 rsl_rll_error(RLL_CAUSE_FRM_UNIMPL, mctx);
424 static int lapdm_send_resend(struct lapdm_datalink *dl)
426 struct msgb *msg = msgb_alloc_headroom(23+10, 10, "LAPDm resend");
429 /* Resend SABM/DISC from tx_hist */
430 length = dl->tx_length[0];
431 msg->l2h = msgb_put(msg, length);
432 memcpy(msg->l2h, dl->tx_hist[dl->V_send], length);
434 return tx_ph_data_enqueue(dl, msg, dl->mctx.chan_nr, dl->mctx.link_id,
438 static int lapdm_send_ua(struct lapdm_msg_ctx *mctx, uint8_t len, uint8_t *data)
440 uint8_t sapi = mctx->link_id & 7;
441 uint8_t f_bit = LAPDm_CTRL_PF_BIT(mctx->ctrl);
442 struct msgb *msg = msgb_alloc_headroom(23+10, 10, "LAPDm UA");
443 msg->l2h = msgb_put(msg, 3 + len);
445 msg->l2h[0] = LAPDm_ADDR(LAPDm_LPD_NORMAL, sapi, CR_MS2BS_RESP);
446 msg->l2h[1] = LAPDm_CTRL_U(LAPDm_U_UA, f_bit);
447 msg->l2h[2] = LAPDm_LEN(len);
449 memcpy(msg->l2h + 3, data, len);
451 return tx_ph_data_enqueue(mctx->dl, msg, mctx->chan_nr, mctx->link_id,
455 static int lapdm_send_dm(struct lapdm_msg_ctx *mctx)
457 uint8_t sapi = mctx->link_id & 7;
458 uint8_t f_bit = LAPDm_CTRL_PF_BIT(mctx->ctrl);
459 struct msgb *msg = msgb_alloc_headroom(23+10, 10, "LAPDm DM");
460 msg->l2h = msgb_put(msg, 3);
462 msg->l2h[0] = LAPDm_ADDR(LAPDm_LPD_NORMAL, sapi, CR_MS2BS_RESP);
463 msg->l2h[1] = LAPDm_CTRL_U(LAPDm_U_DM, f_bit);
466 return tx_ph_data_enqueue(mctx->dl, msg, mctx->chan_nr, mctx->link_id,
470 static int lapdm_send_rr(struct lapdm_msg_ctx *mctx, uint8_t f_bit)
472 uint8_t sapi = mctx->link_id & 7;
473 struct msgb *msg = msgb_alloc_headroom(23+10, 10, "LAPDm RR");
474 msg->l2h = msgb_put(msg, 3);
476 msg->l2h[0] = LAPDm_ADDR(LAPDm_LPD_NORMAL, sapi, CR_MS2BS_RESP);
477 msg->l2h[1] = LAPDm_CTRL_S(mctx->dl->V_recv, LAPDm_S_RR, f_bit);
478 msg->l2h[2] = LAPDm_LEN(0);
480 return tx_ph_data_enqueue(mctx->dl, msg, mctx->chan_nr, mctx->link_id,
484 static int lapdm_send_rnr(struct lapdm_msg_ctx *mctx, uint8_t f_bit)
486 uint8_t sapi = mctx->link_id & 7;
487 struct msgb *msg = msgb_alloc_headroom(23+10, 10, "LAPDm RNR");
488 msg->l2h = msgb_put(msg, 3);
490 msg->l2h[0] = LAPDm_ADDR(LAPDm_LPD_NORMAL, sapi, CR_MS2BS_RESP);
491 msg->l2h[1] = LAPDm_CTRL_S(mctx->dl->V_recv, LAPDm_S_RNR, f_bit);
492 msg->l2h[2] = LAPDm_LEN(0);
494 return tx_ph_data_enqueue(mctx->dl, msg, mctx->chan_nr, mctx->link_id,
498 static int lapdm_send_rej(struct lapdm_msg_ctx *mctx, uint8_t f_bit)
500 uint8_t sapi = mctx->link_id & 7;
501 struct msgb *msg = msgb_alloc_headroom(23+10, 10, "LAPDm REJ");
502 msg->l2h = msgb_put(msg, 3);
504 msg->l2h[0] = LAPDm_ADDR(LAPDm_LPD_NORMAL, sapi, CR_MS2BS_RESP);
505 msg->l2h[1] = LAPDm_CTRL_S(mctx->dl->V_recv, LAPDm_S_REJ, f_bit);
506 msg->l2h[2] = LAPDm_LEN(0);
508 return tx_ph_data_enqueue(mctx->dl, msg, mctx->chan_nr, mctx->link_id,
512 /* Timer callback on T200 expiry */
513 static void lapdm_t200_cb(void *data)
515 struct lapdm_datalink *dl = data;
517 LOGP(DLAPDM, LOGL_INFO, "lapdm_t200_cb(%p) state=%u\n", dl, dl->state);
520 case LAPDm_STATE_SABM_SENT:
522 if (dl->retrans_ctr + 1 >= N200_EST_REL + 1) {
523 /* send RELEASE INDICATION to L3 */
524 send_rll_simple(RSL_MT_REL_IND, &dl->mctx);
525 /* send MDL ERROR INIDCATION to L3 */
526 rsl_rll_error(RLL_CAUSE_T200_EXPIRED, &dl->mctx);
528 lapdm_dl_flush_tx(dl);
529 lapdm_dl_flush_send(dl);
530 /* go back to idle state */
531 lapdm_dl_newstate(dl, LAPDm_STATE_IDLE);
532 /* NOTE: we must not change any other states or buffers
533 * and queues, since we may reconnect after handover
534 * failure. the buffered messages is replaced there */
537 /* retransmit SABM command */
538 lapdm_send_resend(dl);
539 /* increment re-transmission counter */
541 /* restart T200 (PH-READY-TO-SEND) */
542 bsc_schedule_timer(&dl->t200, T200);
544 case LAPDm_STATE_DISC_SENT:
546 if (dl->retrans_ctr + 1 >= N200_EST_REL + 1) {
547 /* send RELEASE INDICATION to L3 */
548 send_rll_simple(RSL_MT_REL_CONF, &dl->mctx);
549 /* send MDL ERROR INIDCATION to L3 */
550 rsl_rll_error(RLL_CAUSE_T200_EXPIRED, &dl->mctx);
552 lapdm_dl_flush_tx(dl);
553 lapdm_dl_flush_send(dl);
554 /* go back to idle state */
555 lapdm_dl_newstate(dl, LAPDm_STATE_IDLE);
556 /* NOTE: we must not change any other states or buffers
557 * and queues, since we may reconnect after handover
558 * failure. the buffered messages is replaced there */
561 /* retransmit DISC command */
562 lapdm_send_resend(dl);
563 /* increment re-transmission counter */
565 /* restart T200 (PH-READY-TO-SEND) */
566 bsc_schedule_timer(&dl->t200, T200);
568 case LAPDm_STATE_MF_EST:
571 lapdm_dl_newstate(dl, LAPDm_STATE_TIMER_RECOV);
573 case LAPDm_STATE_TIMER_RECOV:
575 if (dl->retrans_ctr < N200) {
576 /* retransmit I frame (V_s-1) with P=1, if any */
577 if (dl->tx_length[dl->V_send - 1]) {
581 LOGP(DLAPDM, LOGL_INFO, "retransmit last frame "
582 "V(S)=%d\n", dl->V_send - 1);
583 /* Create I frame (segment) from tx_hist */
584 length = dl->tx_length[dl->V_send - 1];
585 msg = msgb_alloc_headroom(23+10, 10, "LAPDm I");
586 msg->l2h = msgb_put(msg, length);
587 memcpy(msg->l2h, dl->tx_hist[dl->V_send - 1],
589 msg->l2h[1] = LAPDm_CTRL_I(dl->V_recv,
590 dl->V_send - 1, 1); /* P=1 */
591 tx_ph_data_enqueue(dl, msg, dl->mctx.chan_nr,
592 dl->mctx.link_id, dl->mctx.n201);
594 /* OR send appropriate supervision frame with P=1 */
595 if (!dl->own_busy && !dl->seq_err_cond) {
596 lapdm_send_rr(&dl->mctx, 1);
597 /* NOTE: In case of sequence error
598 * condition, the REJ frame has been
599 * transmitted when entering the
600 * condition, so it has not be done
603 } else if (dl->own_busy) {
604 lapdm_send_rnr(&dl->mctx, 1);
606 LOGP(DLAPDM, LOGL_INFO, "unhandled, "
610 /* restart T200 (PH-READY-TO-SEND) */
611 bsc_schedule_timer(&dl->t200, T200);
613 /* send MDL ERROR INIDCATION to L3 */
614 rsl_rll_error(RLL_CAUSE_T200_EXPIRED, &dl->mctx);
618 LOGP(DLAPDM, LOGL_INFO, "T200 expired in unexpected "
619 "dl->state %u\n", dl->state);
623 /* 5.5.3.1: Common function to acknowlege frames up to the given N(R) value */
624 static void lapdm_acknowledge(struct lapdm_msg_ctx *mctx)
626 struct lapdm_datalink *dl = mctx->dl;
627 uint8_t nr = LAPDm_CTRL_Nr(mctx->ctrl);
628 int s = 0, rej = 0, t200_reset = 0;
631 /* supervisory frame ? */
632 if (LAPDm_CTRL_is_S(mctx->ctrl))
635 if (s && LAPDm_CTRL_S_BITS(mctx->ctrl) == LAPDm_S_REJ)
638 /* Flush all transmit buffers of acknowledged frames */
639 for (i = dl->V_ack; i != nr; i = inc_mod8(i)) {
640 if (dl->tx_length[i]) {
641 dl->tx_length[i] = 0;
642 LOGP(DLAPDM, LOGL_INFO, "ack frame %d\n", i);
646 if (dl->state != LAPDm_STATE_TIMER_RECOV) {
647 /* When not in the timer recovery condition, the data
648 * link layer entity shall reset the timer T200 on
649 * receipt of a valid I frame with N(R) higher than V(A),
650 * or an REJ with an N(R) equal to V(A). */
651 if ((!rej && nr != dl->V_ack)
652 || (rej && nr == dl->V_ack)) {
653 LOGP(DLAPDM, LOGL_INFO, "reset t200\n");
655 bsc_del_timer(&dl->t200);
656 /* 5.5.3.1 Note 1 + 2 imply timer recovery cond. */
658 /* 5.7.4: N(R) sequence error
659 * N(R) is called valid, if and only if
660 * (N(R)-V(A)) mod 8 <= (V(S)-V(A)) mod 8.
662 if (sub_mod8(nr, dl->V_ack) > sub_mod8(dl->V_send, dl->V_ack)) {
663 LOGP(DLAPDM, LOGL_NOTICE, "N(R) sequence error\n");
664 rsl_rll_error(RLL_CAUSE_SEQ_ERR, mctx);
668 /* V(A) shall be set to the value of N(R) */
671 /* If T200 has been reset by the receipt of an I, RR or RNR frame,
672 * and if there are outstanding I frames, restart T200 */
673 if (t200_reset && !rej) {
674 if (dl->tx_length[dl->V_send - 1]) {
675 LOGP(DLAPDM, LOGL_INFO, "start T200, due to unacked I "
677 bsc_schedule_timer(&dl->t200, T200);
684 /* Receive a LAPDm U (Unnumbered) message from L1 */
685 static int lapdm_rx_u(struct msgb *msg, struct lapdm_msg_ctx *mctx)
687 struct lapdm_datalink *dl = mctx->dl;
692 switch (LAPDm_CTRL_U_BITS(mctx->ctrl)) {
694 rsl_msg = RSL_MT_EST_IND;
696 LOGP(DLAPDM, LOGL_INFO, "SABM received\n");
698 dl->seq_err_cond = 0;
699 /* G.2.2 Wrong value of the C/R bit */
700 if (LAPDm_ADDR_CR(mctx->addr) == CR_BS2MS_RESP) {
701 LOGP(DLAPDM, LOGL_NOTICE, "SABM response error\n");
703 rsl_rll_error(RLL_CAUSE_FRM_UNIMPL, mctx);
707 length = msg->l2h[2] >> 2;
708 /* G.4.5 If SABM is received with L>N201 or with M bit
709 * set, AN MDL-ERROR-INDICATION is sent to MM.
711 if ((msg->l2h[2] & LAPDm_MORE) || length + 3 > mctx->n201) {
712 LOGP(DLAPDM, LOGL_NOTICE, "SABM too large error\n");
714 rsl_rll_error(RLL_CAUSE_UFRM_INC_PARAM, mctx);
718 /* Must be Format B */
719 rc = check_length_ind(mctx, msg->l2h[2]);
725 case LAPDm_STATE_IDLE:
726 /* Set chan_nr and link_id for established connection */
727 memset(&dl->mctx, 0, sizeof(dl->mctx));
729 dl->mctx.chan_nr = mctx->chan_nr;
730 dl->mctx.link_id = mctx->link_id;
732 case LAPDm_STATE_MF_EST:
734 rsl_msg = RSL_MT_EST_CONF;
737 LOGP(DLAPDM, LOGL_INFO, "SABM command, multiple "
738 "frame established state\n");
739 /* check for contention resoultion */
740 if (dl->tx_hist[0][2] >> 2) {
741 LOGP(DLAPDM, LOGL_NOTICE, "SABM not allowed "
742 "during contention resolution\n");
743 rsl_rll_error(RLL_CAUSE_SABM_INFO_NOTALL, mctx);
747 case LAPDm_STATE_DISC_SENT:
748 /* 5.4.6.2 send DM with F=P */
750 /* reset Timer T200 */
751 bsc_del_timer(&dl->t200);
753 return send_rll_simple(RSL_MT_REL_CONF, mctx);
755 lapdm_send_ua(mctx, length, msg->l2h + 3);
759 /* send UA response */
760 lapdm_send_ua(mctx, length, msg->l2h + 3);
761 /* set Vs, Vr and Va to 0 */
762 dl->V_send = dl->V_recv = dl->V_ack = 0;
764 dl->tx_length[0] = 0;
765 /* enter multiple-frame-established state */
766 lapdm_dl_newstate(dl, LAPDm_STATE_MF_EST);
767 /* send notification to L3 */
769 /* 5.4.1.2 Normal establishment procedures */
770 rc = send_rll_simple(rsl_msg, mctx);
773 /* 5.4.1.4 Contention resolution establishment */
774 msg->l3h = msg->l2h + 3;
776 rc = send_rslms_rll_l3(rsl_msg, mctx, msg);
780 LOGP(DLAPDM, LOGL_INFO, "DM received\n");
781 /* G.2.2 Wrong value of the C/R bit */
782 if (LAPDm_ADDR_CR(mctx->addr) == CR_BS2MS_CMD) {
783 LOGP(DLAPDM, LOGL_NOTICE, "DM command error\n");
785 rsl_rll_error(RLL_CAUSE_FRM_UNIMPL, mctx);
788 if (!LAPDm_CTRL_PF_BIT(mctx->ctrl)) {
789 /* 5.4.1.2 DM responses with the F bit set to "0"
796 case LAPDm_STATE_SABM_SENT:
798 case LAPDm_STATE_MF_EST:
799 if (LAPDm_CTRL_PF_BIT(mctx->ctrl) == 1) {
800 LOGP(DLAPDM, LOGL_INFO, "unsolicited DM "
802 rsl_rll_error(RLL_CAUSE_UNSOL_DM_RESP, mctx);
804 LOGP(DLAPDM, LOGL_INFO, "unsolicited DM "
805 "response, multiple frame established "
807 rsl_rll_error(RLL_CAUSE_UNSOL_DM_RESP_MF, mctx);
811 case LAPDm_STATE_TIMER_RECOV:
812 /* DM is normal in case PF = 1 */
813 if (LAPDm_CTRL_PF_BIT(mctx->ctrl) == 0) {
814 LOGP(DLAPDM, LOGL_INFO, "unsolicited DM "
815 "response, multiple frame established "
817 rsl_rll_error(RLL_CAUSE_UNSOL_DM_RESP_MF, mctx);
822 case LAPDm_STATE_DISC_SENT:
823 /* reset Timer T200 */
824 bsc_del_timer(&dl->t200);
825 /* go to idle state */
826 lapdm_dl_newstate(dl, LAPDm_STATE_IDLE);
827 rc = send_rll_simple(RSL_MT_REL_CONF, mctx);
830 case LAPDm_STATE_IDLE:
831 /* 5.4.5 all other frame types shall be discarded */
833 LOGP(DLAPDM, LOGL_INFO, "unsolicited DM response! "
839 bsc_del_timer(&dl->t200);
840 rc = send_rll_simple(RSL_MT_REL_IND, mctx);
844 LOGP(DLAPDM, LOGL_INFO, "UI received\n");
845 /* G.2.2 Wrong value of the C/R bit */
846 if (LAPDm_ADDR_CR(mctx->addr) == CR_BS2MS_RESP) {
847 LOGP(DLAPDM, LOGL_NOTICE, "UI indicates response "
850 rsl_rll_error(RLL_CAUSE_FRM_UNIMPL, mctx);
854 length = msg->l2h[2] >> 2;
855 /* FIXME: G.4.5 If UI is received with L>N201 or with M bit
856 * set, AN MDL-ERROR-INDICATION is sent to MM.
859 if (mctx->lapdm_fmt == LAPDm_FMT_B4) {
861 msg->l3h = msg->l2h + 2;
863 rc = check_length_ind(mctx, msg->l2h[2]);
868 length = msg->l2h[2] >> 2;
869 msg->l3h = msg->l2h + 3;
871 /* do some length checks */
873 /* 5.3.3 UI frames received with the length indicator
874 * set to "0" shall be ignored
876 LOGP(DLAPDM, LOGL_INFO, "length=0 (discarding)\n");
880 switch (LAPDm_ADDR_SAPI(mctx->addr)) {
881 case LAPDm_SAPI_NORMAL:
885 /* 5.3.3 UI frames with invalid SAPI values shall be
888 LOGP(DLAPDM, LOGL_INFO, "sapi=%u (discarding)\n",
889 LAPDm_ADDR_SAPI(mctx->addr));
894 rc = send_rslms_rll_l3_ui(mctx, msg);
897 rsl_msg = RSL_MT_REL_IND;
899 LOGP(DLAPDM, LOGL_INFO, "DISC received\n");
901 lapdm_dl_flush_tx(dl);
902 lapdm_dl_flush_send(dl);
904 dl->seq_err_cond = 0;
905 /* G.2.2 Wrong value of the C/R bit */
906 if (LAPDm_ADDR_CR(mctx->addr) == CR_BS2MS_RESP) {
907 LOGP(DLAPDM, LOGL_NOTICE, "DISC response error\n");
909 rsl_rll_error(RLL_CAUSE_FRM_UNIMPL, mctx);
912 length = msg->l2h[2] >> 2;
913 if (length > 0 || msg->l2h[2] & 0x02) {
914 /* G.4.4 If a DISC or DM frame is received with L>0 or
915 * with the M bit set to "1", an MDL-ERROR-INDICATION
916 * primitive with cause "U frame with incorrect
917 * parameters" is sent to the mobile management entity.
919 LOGP(DLAPDM, LOGL_NOTICE,
920 "U frame iwth incorrect parameters ");
922 rsl_rll_error(RLL_CAUSE_UFRM_INC_PARAM, mctx);
927 case LAPDm_STATE_IDLE:
928 LOGP(DLAPDM, LOGL_INFO, "DISC in idle state\n");
929 /* send DM with F=P */
930 return lapdm_send_dm(mctx);
931 case LAPDm_STATE_SABM_SENT:
932 LOGP(DLAPDM, LOGL_INFO, "DISC in SABM state\n");
933 /* 5.4.6.2 send DM with F=P */
935 /* reset Timer T200 */
936 bsc_del_timer(&dl->t200);
937 return send_rll_simple(RSL_MT_REL_IND, mctx);
938 case LAPDm_STATE_MF_EST:
939 case LAPDm_STATE_TIMER_RECOV:
940 LOGP(DLAPDM, LOGL_INFO, "DISC in est state\n");
942 case LAPDm_STATE_DISC_SENT:
943 LOGP(DLAPDM, LOGL_INFO, "DISC in disc state\n");
944 rsl_msg = RSL_MT_REL_CONF;
947 lapdm_send_ua(mctx, length, msg->l2h + 3);
950 /* send UA response */
951 lapdm_send_ua(mctx, length, msg->l2h + 3);
952 /* reset Timer T200 */
953 bsc_del_timer(&dl->t200);
954 /* enter idle state */
955 lapdm_dl_newstate(dl, LAPDm_STATE_IDLE);
956 /* send notification to L3 */
957 rc = send_rll_simple(rsl_msg, mctx);
960 LOGP(DLAPDM, LOGL_INFO, "UA received\n");
961 /* G.2.2 Wrong value of the C/R bit */
962 if (LAPDm_ADDR_CR(mctx->addr) == CR_BS2MS_CMD) {
963 LOGP(DLAPDM, LOGL_NOTICE, "UA indicates command "
966 rsl_rll_error(RLL_CAUSE_FRM_UNIMPL, mctx);
970 length = msg->l2h[2] >> 2;
971 /* G.4.5 If UA is received with L>N201 or with M bit
972 * set, AN MDL-ERROR-INDICATION is sent to MM.
974 if ((msg->l2h[2] & LAPDm_MORE) || length + 3 > mctx->n201) {
975 LOGP(DLAPDM, LOGL_NOTICE, "UA too large error\n");
977 rsl_rll_error(RLL_CAUSE_UFRM_INC_PARAM, mctx);
981 if (!LAPDm_CTRL_PF_BIT(mctx->ctrl)) {
982 /* 5.4.1.2 A UA response with the F bit set to "0"
985 LOGP(DLAPDM, LOGL_INFO, "F=0 (discarding)\n");
990 case LAPDm_STATE_SABM_SENT:
992 case LAPDm_STATE_MF_EST:
993 case LAPDm_STATE_TIMER_RECOV:
994 LOGP(DLAPDM, LOGL_INFO, "unsolicited UA response! "
996 rsl_rll_error(RLL_CAUSE_UNSOL_UA_RESP, mctx);
999 case LAPDm_STATE_DISC_SENT:
1000 LOGP(DLAPDM, LOGL_INFO, "UA in disconnect state\n");
1001 /* reset Timer T200 */
1002 bsc_del_timer(&dl->t200);
1003 /* go to idle state */
1004 lapdm_dl_newstate(dl, LAPDm_STATE_IDLE);
1005 rc = send_rll_simple(RSL_MT_REL_CONF, mctx);
1008 case LAPDm_STATE_IDLE:
1009 /* 5.4.5 all other frame types shall be discarded */
1011 LOGP(DLAPDM, LOGL_INFO, "unsolicited UA response! "
1016 LOGP(DLAPDM, LOGL_INFO, "UA in SABM state\n");
1017 /* reset Timer T200 */
1018 bsc_del_timer(&dl->t200);
1019 /* compare UA with SABME if contention resolution is applied */
1020 if (dl->tx_hist[0][2] >> 2) {
1021 rc = check_length_ind(mctx, msg->l2h[2]);
1023 rc = send_rll_simple(RSL_MT_REL_IND, mctx);
1025 /* go to idle state */
1026 lapdm_dl_newstate(dl, LAPDm_STATE_IDLE);
1029 length = msg->l2h[2] >> 2;
1030 if (length != (dl->tx_hist[0][2] >> 2)
1031 || !!memcmp(dl->tx_hist[0] + 3, msg->l2h + 3,
1033 LOGP(DLAPDM, LOGL_INFO, "**** UA response "
1034 "mismatches ****\n");
1035 rc = send_rll_simple(RSL_MT_REL_IND, mctx);
1037 /* go to idle state */
1038 lapdm_dl_newstate(dl, LAPDm_STATE_IDLE);
1042 /* set Vs, Vr and Va to 0 */
1043 dl->V_send = dl->V_recv = dl->V_ack = 0;
1045 dl->tx_length[0] = 0;
1046 /* enter multiple-frame-established state */
1047 lapdm_dl_newstate(dl, LAPDm_STATE_MF_EST);
1048 /* send outstanding frames, if any (resume / reconnect) */
1050 /* send notification to L3 */
1051 rc = send_rll_simple(RSL_MT_EST_CONF, mctx);
1056 LOGP(DLAPDM, LOGL_NOTICE, "Unnumbered frame not allowed.\n");
1058 rsl_rll_error(RLL_CAUSE_FRM_UNIMPL, mctx);
1064 /* Receive a LAPDm S (Supervisory) message from L1 */
1065 static int lapdm_rx_s(struct msgb *msg, struct lapdm_msg_ctx *mctx)
1067 struct lapdm_datalink *dl = mctx->dl;
1070 length = msg->l2h[2] >> 2;
1071 if (length > 0 || msg->l2h[2] & 0x02) {
1072 /* G.4.3 If a supervisory frame is received with L>0 or
1073 * with the M bit set to "1", an MDL-ERROR-INDICATION
1074 * primitive with cause "S frame with incorrect
1075 * parameters" is sent to the mobile management entity. */
1076 LOGP(DLAPDM, LOGL_NOTICE,
1077 "S frame with incorrect parameters\n");
1079 rsl_rll_error(RLL_CAUSE_SFRM_INC_PARAM, mctx);
1082 /* 5.4.2.2: Inidcate error on supervisory reponse F=1 */
1083 if (LAPDm_ADDR_CR(mctx->addr) == CR_BS2MS_RESP
1084 && LAPDm_CTRL_PF_BIT(mctx->ctrl)) {
1085 LOGP(DLAPDM, LOGL_NOTICE, "S frame response with F=1 error\n");
1086 rsl_rll_error(RLL_CAUSE_UNSOL_SPRV_RESP, mctx);
1089 switch (dl->state) {
1090 case LAPDm_STATE_IDLE:
1091 /* if P=1, respond DM with F=1 (5.2.2) */
1092 /* 5.4.5 all other frame types shall be discarded */
1093 if (LAPDm_CTRL_PF_BIT(mctx->ctrl))
1094 lapdm_send_dm(mctx); /* F=P */
1096 case LAPDm_STATE_SABM_SENT:
1097 case LAPDm_STATE_DISC_SENT:
1098 LOGP(DLAPDM, LOGL_NOTICE, "S frame ignored in this state\n");
1102 switch (LAPDm_CTRL_S_BITS(mctx->ctrl)) {
1104 LOGP(DLAPDM, LOGL_INFO, "RR received\n");
1105 /* 5.5.3.1: Acknowlege all tx frames up the the N(R)-1 */
1106 lapdm_acknowledge(mctx);
1109 if (LAPDm_ADDR_CR(mctx->addr) == CR_BS2MS_CMD
1110 && LAPDm_CTRL_PF_BIT(mctx->ctrl)) {
1111 if (!dl->own_busy && !dl->seq_err_cond) {
1112 LOGP(DLAPDM, LOGL_NOTICE, "RR frame command "
1113 "with polling bit set and we are not "
1114 "busy, so we reply with RR frame\n");
1115 lapdm_send_rr(mctx, 1);
1116 /* NOTE: In case of sequence error condition,
1117 * the REJ frame has been transmitted when
1118 * entering the condition, so it has not be
1121 } else if (dl->own_busy) {
1122 LOGP(DLAPDM, LOGL_NOTICE, "RR frame command "
1123 "with polling bit set and we are busy, "
1124 "so we reply with RR frame\n");
1125 lapdm_send_rnr(mctx, 1);
1128 /* Send message, if possible due to acknowledged data */
1133 LOGP(DLAPDM, LOGL_INFO, "RNR received\n");
1134 /* 5.5.3.1: Acknowlege all tx frames up the the N(R)-1 */
1135 lapdm_acknowledge(mctx);
1138 /* Set peer receiver busy condition */
1141 if (LAPDm_CTRL_PF_BIT(mctx->ctrl)) {
1142 if (LAPDm_ADDR_CR(mctx->addr) == CR_BS2MS_CMD) {
1143 if (!dl->own_busy) {
1144 LOGP(DLAPDM, LOGL_INFO, "RNR poll "
1145 "command and we are not busy, "
1146 "so we reply with RR final "
1148 /* Send RR with F=1 */
1149 lapdm_send_rr(mctx, 1);
1151 LOGP(DLAPDM, LOGL_INFO, "RNR poll "
1152 "command and we are busy, so "
1153 "we reply with RNR final "
1155 /* Send RNR with F=1 */
1156 lapdm_send_rnr(mctx, 1);
1158 } else if (dl->state == LAPDm_STATE_TIMER_RECOV) {
1159 LOGP(DLAPDM, LOGL_INFO, "RNR poll response "
1160 "and we in timer recovery state, so "
1161 "we leave that state\n");
1162 /* Clear timer recovery condition */
1163 lapdm_dl_newstate(dl, LAPDm_STATE_MF_EST);
1164 /* V(S) to the N(R) in the RNR frame */
1165 dl->V_send = LAPDm_CTRL_Nr(mctx->ctrl);
1168 LOGP(DLAPDM, LOGL_INFO, "RNR not polling/final state "
1171 /* Send message, if possible due to acknowledged data */
1176 LOGP(DLAPDM, LOGL_INFO, "REJ received\n");
1177 /* 5.5.3.1: Acknowlege all tx frames up the the N(R)-1 */
1178 lapdm_acknowledge(mctx);
1181 if (dl->state != LAPDm_STATE_TIMER_RECOV) {
1182 /* Clear an existing peer receiver busy condition */
1184 /* V(S) and V(A) to the N(R) in the REJ frame */
1185 dl->V_send = dl->V_ack = LAPDm_CTRL_Nr(mctx->ctrl);
1186 /* reset Timer T200 */
1187 bsc_del_timer(&dl->t200);
1189 if (LAPDm_ADDR_CR(mctx->addr) == CR_BS2MS_CMD
1190 && LAPDm_CTRL_PF_BIT(mctx->ctrl)) {
1191 if (!dl->own_busy && !dl->seq_err_cond) {
1192 LOGP(DLAPDM, LOGL_INFO, "REJ poll "
1193 "command not in timer recovery "
1194 "state and not in own busy "
1195 "condition received, so we "
1196 "respond with RR final "
1198 lapdm_send_rr(mctx, 1);
1199 /* NOTE: In case of sequence error
1200 * condition, the REJ frame has been
1201 * transmitted when entering the
1202 * condition, so it has not be done
1205 } else if (dl->own_busy) {
1206 LOGP(DLAPDM, LOGL_INFO, "REJ poll "
1207 "command not in timer recovery "
1208 "state and in own busy "
1209 "condition received, so we "
1210 "respond with RNR final "
1212 lapdm_send_rnr(mctx, 1);
1215 LOGP(DLAPDM, LOGL_INFO, "REJ response or not "
1216 "polling command not in timer recovery "
1217 "state received\n");
1218 /* send MDL ERROR INIDCATION to L3 */
1219 if (LAPDm_ADDR_CR(mctx->addr) == CR_BS2MS_RESP
1220 && LAPDm_CTRL_PF_BIT(mctx->ctrl)) {
1221 rsl_rll_error(RLL_CAUSE_UNSOL_SPRV_RESP, mctx);
1224 } else if (LAPDm_ADDR_CR(mctx->addr) == CR_BS2MS_RESP
1225 && LAPDm_CTRL_PF_BIT(mctx->ctrl)) {
1226 LOGP(DLAPDM, LOGL_INFO, "REJ poll response in timer "
1227 "recovery state received\n");
1228 /* Clear an existing peer receiver busy condition */
1230 /* Clear timer recovery condition */
1231 lapdm_dl_newstate(dl, LAPDm_STATE_MF_EST);
1232 /* V(S) and V(A) to the N(R) in the REJ frame */
1233 dl->V_send = dl->V_ack = LAPDm_CTRL_Nr(mctx->ctrl);
1234 /* reset Timer T200 */
1235 bsc_del_timer(&dl->t200);
1237 /* Clear an existing peer receiver busy condition */
1239 /* V(S) and V(A) to the N(R) in the REJ frame */
1240 dl->V_send = dl->V_ack = LAPDm_CTRL_Nr(mctx->ctrl);
1242 if (LAPDm_ADDR_CR(mctx->addr) == CR_BS2MS_CMD
1243 && LAPDm_CTRL_PF_BIT(mctx->ctrl)) {
1244 if (!dl->own_busy && !dl->seq_err_cond) {
1245 LOGP(DLAPDM, LOGL_INFO, "REJ poll "
1246 "command in timer recovery "
1247 "state and not in own busy "
1248 "condition received, so we "
1249 "respond with RR final "
1251 lapdm_send_rr(mctx, 1);
1252 /* NOTE: In case of sequence error
1253 * condition, the REJ frame has been
1254 * transmitted when entering the
1255 * condition, so it has not be done
1258 } else if (dl->own_busy) {
1259 LOGP(DLAPDM, LOGL_INFO, "REJ poll "
1260 "command in timer recovery "
1261 "state and in own busy "
1262 "condition received, so we "
1263 "respond with RNR final "
1265 lapdm_send_rnr(mctx, 1);
1268 LOGP(DLAPDM, LOGL_INFO, "REJ response or not "
1269 "polling command in timer recovery "
1270 "state received\n");
1273 /* FIXME: 5.5.4.2 2) */
1275 /* Send message, if possible due to acknowledged data */
1281 LOGP(DLAPDM, LOGL_NOTICE, "Supervisory frame not allowed.\n");
1283 rsl_rll_error(RLL_CAUSE_FRM_UNIMPL, mctx);
1290 /* Receive a LAPDm I (Information) message from L1 */
1291 static int lapdm_rx_i(struct msgb *msg, struct lapdm_msg_ctx *mctx)
1293 struct lapdm_datalink *dl = mctx->dl;
1294 //uint8_t nr = LAPDm_CTRL_Nr(mctx->ctrl);
1295 uint8_t ns = LAPDm_CTRL_I_Ns(mctx->ctrl);
1299 LOGP(DLAPDM, LOGL_NOTICE, "I received\n");
1301 /* G.2.2 Wrong value of the C/R bit */
1302 if (LAPDm_ADDR_CR(mctx->addr) == CR_BS2MS_RESP) {
1303 LOGP(DLAPDM, LOGL_NOTICE, "I frame response not allowed\n");
1305 rsl_rll_error(RLL_CAUSE_FRM_UNIMPL, mctx);
1309 length = msg->l2h[2] >> 2;
1310 if (length == 0 || length + 3 > mctx->n201) {
1311 /* G.4.2 If the length indicator of an I frame is set
1312 * to a numerical value L>N201 or L=0, an MDL-ERROR-INDICATION
1313 * primitive with cause "I frame with incorrect length"
1314 * is sent to the mobile management entity. */
1315 LOGP(DLAPDM, LOGL_NOTICE, "I frame length not allowed\n");
1317 rsl_rll_error(RLL_CAUSE_IFRM_INC_LEN, mctx);
1321 /* G.4.2 If the numerical value of L is L<N201 and the M
1322 * bit is set to "1", then an MDL-ERROR-INDICATION primitive with
1323 * cause "I frame with incorrect use of M bit" is sent to the
1324 * mobile management entity. */
1325 if ((msg->l2h[2] & LAPDm_MORE) && length + 3 < mctx->n201) {
1326 LOGP(DLAPDM, LOGL_NOTICE, "I frame with M bit too short\n");
1328 rsl_rll_error(RLL_CAUSE_IFRM_INC_MBITS, mctx);
1332 switch (dl->state) {
1333 case LAPDm_STATE_IDLE:
1334 /* if P=1, respond DM with F=1 (5.2.2) */
1335 /* 5.4.5 all other frame types shall be discarded */
1336 if (LAPDm_CTRL_PF_BIT(mctx->ctrl))
1337 lapdm_send_dm(mctx); /* F=P */
1339 case LAPDm_STATE_SABM_SENT:
1340 case LAPDm_STATE_DISC_SENT:
1341 LOGP(DLAPDM, LOGL_NOTICE, "I frame ignored in this state\n");
1346 /* 5.7.1: N(s) sequence error */
1347 if (ns != dl->V_recv) {
1348 LOGP(DLAPDM, LOGL_NOTICE, "N(S) sequence error: N(S)=%u, "
1349 "V(R)=%u\n", ns, dl->V_recv);
1352 if (!dl->seq_err_cond) {
1353 /* FIXME: help me understand what exactly todo here
1354 dl->seq_err_cond = 1;
1356 lapdm_send_rej(mctx, LAPDm_CTRL_PF_BIT(mctx->ctrl));
1361 dl->seq_err_cond = 0;
1363 /* Increment receiver state */
1364 dl->V_recv = inc_mod8(dl->V_recv);
1365 LOGP(DLAPDM, LOGL_NOTICE, "incrementing V(R) to %u\n", dl->V_recv);
1367 /* 5.5.3.1: Acknowlege all transmitted frames up the the N(R)-1 */
1368 lapdm_acknowledge(mctx); /* V(A) is also set here */
1370 /* Only if we are not in own receiver busy condition */
1371 if (!dl->own_busy) {
1372 /* if the frame carries a complete segment */
1373 if (!(msg->l2h[2] & LAPDm_MORE)
1374 && !dl->rcv_buffer) {
1375 LOGP(DLAPDM, LOGL_INFO, "message in single I frame\n");
1376 /* send a DATA INDICATION to L3 */
1377 msg->l3h = msg->l2h + 3;
1379 rc = send_rslms_rll_l3(RSL_MT_DATA_IND, mctx, msg);
1381 /* create rcv_buffer */
1382 if (!dl->rcv_buffer) {
1383 LOGP(DLAPDM, LOGL_INFO, "message in multiple I "
1384 "frames (first message)\n");
1385 dl->rcv_buffer = msgb_alloc_headroom(200+56, 56,
1387 dl->rcv_buffer->l3h = dl->rcv_buffer->data;
1389 /* concat. rcv_buffer */
1390 if (msgb_l3len(dl->rcv_buffer) + length > 200) {
1391 LOGP(DLAPDM, LOGL_NOTICE, "Received frame "
1394 memcpy(msgb_put(dl->rcv_buffer, length),
1395 msg->l2h + 3, length);
1397 /* if the last segment was received */
1398 if (!(msg->l2h[2] & LAPDm_MORE)) {
1399 LOGP(DLAPDM, LOGL_INFO, "message in multiple I "
1400 "frames (next message)\n");
1401 rc = send_rslms_rll_l3(RSL_MT_DATA_IND, mctx,
1403 dl->rcv_buffer = NULL;
1405 LOGP(DLAPDM, LOGL_INFO, "message in multiple I "
1406 "frames (last message)\n");
1411 LOGP(DLAPDM, LOGL_INFO, "I frame ignored during own receiver "
1412 "busy condition\n");
1414 /* Check for P bit */
1415 if (LAPDm_CTRL_PF_BIT(mctx->ctrl)) {
1417 /* check if we are not in own receiver busy */
1418 if (!dl->own_busy) {
1419 LOGP(DLAPDM, LOGL_INFO, "we are not busy, send RR\n");
1420 /* Send RR with F=1 */
1421 rc = lapdm_send_rr(mctx, 1);
1423 LOGP(DLAPDM, LOGL_INFO, "we are busy, send RNR\n");
1424 /* Send RNR with F=1 */
1425 rc = lapdm_send_rnr(mctx, 1);
1429 /* check if we are not in own receiver busy */
1430 if (!dl->own_busy) {
1431 /* NOTE: V(R) is already set above */
1432 rc = rslms_send_i(mctx);
1434 LOGP(DLAPDM, LOGL_INFO, "we are not busy and "
1435 "have no pending data, send RR\n");
1436 /* Send RR with F=0 */
1437 return lapdm_send_rr(mctx, 0);
1440 LOGP(DLAPDM, LOGL_INFO, "we are busy, send RNR\n");
1441 /* Send RNR with F=0 */
1442 rc = lapdm_send_rnr(mctx, 0);
1446 /* Send message, if possible due to acknowledged data */
1452 /* Receive a LAPDm message from L1 */
1453 static int lapdm_ph_data_ind(struct msgb *msg, struct lapdm_msg_ctx *mctx)
1457 /* G.2.3 EA bit set to "0" is not allowed in GSM */
1458 if (!LAPDm_ADDR_EA(mctx->addr)) {
1459 LOGP(DLAPDM, LOGL_NOTICE, "EA bit 0 is not allowed in GSM\n");
1461 rsl_rll_error(RLL_CAUSE_FRM_UNIMPL, mctx);
1465 if (LAPDm_CTRL_is_U(mctx->ctrl))
1466 rc = lapdm_rx_u(msg, mctx);
1467 else if (LAPDm_CTRL_is_S(mctx->ctrl))
1468 rc = lapdm_rx_s(msg, mctx);
1469 else if (LAPDm_CTRL_is_I(mctx->ctrl))
1470 rc = lapdm_rx_i(msg, mctx);
1472 LOGP(DLAPDM, LOGL_NOTICE, "unknown LAPDm format\n");
1479 /* input into layer2 (from layer 1) */
1480 int l2_ph_data_ind(struct msgb *msg, struct lapdm_entity *le, struct l1ctl_info_dl *l1i)
1482 uint8_t cbits = l1i->chan_nr >> 3;
1483 uint8_t sapi = l1i->link_id & 7;
1484 struct lapdm_msg_ctx mctx;
1487 /* when we reach here, we have a msgb with l2h pointing to the raw
1488 * 23byte mac block. The l1h has already been purged. */
1490 mctx.dl = datalink_for_sapi(le, sapi);
1491 mctx.chan_nr = l1i->chan_nr;
1492 mctx.link_id = l1i->link_id;
1493 mctx.addr = mctx.ctrl = 0;
1495 /* G.2.1 No action schall be taken on frames containing an unallocated
1499 LOGP(DLAPDM, LOGL_NOTICE, "Received frame for unsupported "
1500 "SAPI %d!\n", sapi);
1506 /* check for L1 chan_nr/link_id and determine LAPDm hdr format */
1507 if (cbits == 0x10 || cbits == 0x12) {
1508 /* Format Bbis is used on BCCH and CCCH(PCH, NCH and AGCH) */
1509 mctx.lapdm_fmt = LAPDm_FMT_Bbis;
1510 mctx.n201 = N201_Bbis;
1512 if (mctx.link_id & 0x40) {
1513 /* It was received from network on SACCH, thus
1514 * lapdm_fmt must be B4 */
1515 mctx.lapdm_fmt = LAPDm_FMT_B4;
1516 mctx.n201 = N201_B4;
1517 LOGP(DLAPDM, LOGL_INFO, "fmt=B4\n");
1518 /* SACCH frames have a two-byte L1 header that
1519 * OsmocomBB L1 doesn't strip */
1520 mctx.tx_power_ind = msg->l2h[0] & 0x1f;
1521 mctx.ta_ind = msg->l2h[1];
1525 mctx.lapdm_fmt = LAPDm_FMT_B;
1526 LOGP(DLAPDM, LOGL_INFO, "fmt=B\n");
1527 mctx.n201 = 23; // FIXME: select correct size by chan.
1531 switch (mctx.lapdm_fmt) {
1535 mctx.addr = msg->l2h[0];
1536 if (!(mctx.addr & 0x01)) {
1537 LOGP(DLAPDM, LOGL_ERROR, "we don't support "
1538 "multibyte addresses (discarding)\n");
1542 mctx.ctrl = msg->l2h[1];
1543 /* obtain SAPI from address field */
1544 mctx.link_id |= LAPDm_ADDR_SAPI(mctx.addr);
1545 rc = lapdm_ph_data_ind(msg, &mctx);
1547 case LAPDm_FMT_Bter:
1551 case LAPDm_FMT_Bbis:
1552 /* directly pass up to layer3 */
1553 LOGP(DLAPDM, LOGL_INFO, "fmt=Bbis UI\n");
1554 msg->l3h = msg->l2h;
1556 rc = send_rslms_rll_l3(RSL_MT_UNIT_DATA_IND, &mctx, msg);
1565 /* L3 -> L2 / RSLMS -> LAPDm */
1567 /* L3 requests establishment of data link */
1568 static int rslms_rx_rll_est_req(struct msgb *msg, struct lapdm_datalink *dl)
1570 struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
1571 uint8_t chan_nr = rllh->chan_nr;
1572 uint8_t link_id = rllh->link_id;
1573 uint8_t sapi = rllh->link_id & 7;
1574 struct tlv_parsed tv;
1576 uint8_t n201 = 23; //FIXME
1578 /* Set chan_nr and link_id for established connection */
1579 memset(&dl->mctx, 0, sizeof(dl->mctx));
1581 dl->mctx.n201 = n201;
1582 dl->mctx.chan_nr = chan_nr;
1583 dl->mctx.link_id = link_id;
1585 rsl_tlv_parse(&tv, rllh->data, msgb_l2len(msg)-sizeof(*rllh));
1586 if (TLVP_PRESENT(&tv, RSL_IE_L3_INFO)) {
1587 /* contention resolution establishment procedure */
1589 /* According to clause 6, the contention resolution
1590 * procedure is only permitted with SAPI value 0 */
1591 LOGP(DLAPDM, LOGL_ERROR, "SAPI != 0 but contention"
1592 "resolution (discarding)\n");
1594 return send_rll_simple(RSL_MT_REL_IND, &dl->mctx);
1596 /* transmit a SABM command with the P bit set to "1". The SABM
1597 * command shall contain the layer 3 message unit */
1598 length = TLVP_LEN(&tv, RSL_IE_L3_INFO);
1599 LOGP(DLAPDM, LOGL_INFO, "perform establishment with content "
1602 /* normal establishment procedure */
1604 LOGP(DLAPDM, LOGL_INFO, "perform normal establishm. (SAMB)\n");
1607 /* check if the layer3 message length exceeds N201 */
1608 if (length + 3 > 21) { /* FIXME: do we know the channel N201? */
1609 LOGP(DLAPDM, LOGL_ERROR, "frame too large: %d > N201(%d) "
1610 "(discarding)\n", length + 3, 21);
1612 return send_rll_simple(RSL_MT_REL_IND, &dl->mctx);
1615 /* Flush send-queue */
1616 /* Clear send-buffer */
1617 lapdm_dl_flush_send(dl);
1619 /* Discard partly received L3 message */
1620 if (dl->rcv_buffer) {
1621 msgb_free(dl->rcv_buffer);
1622 dl->rcv_buffer = NULL;
1625 /* Remove RLL header from msgb */
1628 /* Push LAPDm header on msgb */
1629 msg->l2h = msgb_push(msg, 3);
1630 msg->l2h[0] = LAPDm_ADDR(LAPDm_LPD_NORMAL, sapi, CR_MS2BS_CMD);
1631 msg->l2h[1] = LAPDm_CTRL_U(LAPDm_U_SABM, 1);
1632 msg->l2h[2] = LAPDm_LEN(length);
1633 /* Transmit-buffer carries exactly one segment */
1634 memcpy(dl->tx_hist[0], msg->l2h, 3 + length);
1635 dl->tx_length[0] = 3 + length;
1636 /* set Vs to 0, because it is used as index when resending SAMB */
1640 dl->own_busy = dl->peer_busy = 0;
1641 dl->retrans_ctr = 0;
1642 lapdm_dl_newstate(dl, LAPDm_STATE_SABM_SENT);
1644 /* Tramsmit and start T200 */
1645 bsc_schedule_timer(&dl->t200, T200);
1646 return tx_ph_data_enqueue(dl, msg, chan_nr, link_id, n201);
1649 /* L3 requests transfer of unnumbered information */
1650 static int rslms_rx_rll_udata_req(struct msgb *msg, struct lapdm_datalink *dl)
1652 struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
1653 uint8_t chan_nr = rllh->chan_nr;
1654 uint8_t link_id = rllh->link_id;
1655 uint8_t sapi = link_id & 7;
1656 struct tlv_parsed tv;
1658 uint8_t n201 = 23; //FIXME
1660 /* check if the layer3 message length exceeds N201 */
1662 rsl_tlv_parse(&tv, rllh->data, msgb_l2len(msg)-sizeof(*rllh));
1664 length = TLVP_LEN(&tv, RSL_IE_L3_INFO);
1665 /* check if the layer3 message length exceeds N201 */
1666 if (length + 3 > 18) { /* FIXME: do we know the channel N201? */
1667 LOGP(DLAPDM, LOGL_ERROR, "frame too large: %d > N201(%d) "
1668 "(discarding)\n", length + 3, 18);
1673 LOGP(DLAPDM, LOGL_INFO, "sending unit data\n");
1675 /* Remove RLL header from msgb */
1678 /* Push LAPDm header on msgb */
1679 msg->l2h = msgb_push(msg, 3);
1680 msg->l2h[0] = LAPDm_ADDR(LAPDm_LPD_NORMAL, sapi, CR_MS2BS_CMD);
1681 msg->l2h[1] = LAPDm_CTRL_U(LAPDm_U_UI, 0);
1682 msg->l2h[2] = LAPDm_LEN(length);
1683 // FIXME: short L2 header support
1686 return tx_ph_data_enqueue(dl, msg, chan_nr, link_id, n201);
1689 /* L3 requests transfer of acknowledged information */
1690 static int rslms_rx_rll_data_req(struct msgb *msg, struct lapdm_datalink *dl)
1692 struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
1693 struct tlv_parsed tv;
1695 rsl_tlv_parse(&tv, rllh->data, msgb_l2len(msg)-sizeof(*rllh));
1696 if (!TLVP_PRESENT(&tv, RSL_IE_L3_INFO)) {
1697 LOGP(DLAPDM, LOGL_ERROR, "data request without message "
1703 LOGP(DLAPDM, LOGL_INFO, "writing message to send-queue\n");
1705 /* Remove the RSL/RLL header */
1708 /* Write data into the send queue */
1709 msgb_enqueue(&dl->send_queue, msg);
1711 /* Send message, if possible */
1712 rslms_send_i(&dl->mctx);
1716 /* Send next I frame from queued/buffered data */
1717 static int rslms_send_i(struct lapdm_msg_ctx *mctx)
1719 struct lapdm_datalink *dl = mctx->dl;
1720 uint8_t chan_nr = mctx->chan_nr;
1721 uint8_t link_id = mctx->link_id;
1722 uint8_t sapi = link_id & 7;
1723 int k = k_sapi[sapi];
1726 int rc = -1; /* we sent nothing */
1730 if (dl->peer_busy) {
1731 LOGP(DLAPDM, LOGL_INFO, "peer busy, not sending\n");
1735 if (dl->state == LAPDm_STATE_TIMER_RECOV) {
1736 LOGP(DLAPDM, LOGL_INFO, "timer recovery, not sending\n");
1740 /* If the send state variable V(S) is equal to V(A) plus k
1741 * (where k is the maximum number of outstanding I frames - see
1742 * subclause 5.8.4), the data link layer entity shall not transmit any
1743 * new I frames, but shall retransmit an I frame as a result
1744 * of the error recovery procedures as described in subclauses 5.5.4 and
1746 if (dl->V_send == add_mod8(dl->V_ack, k)) {
1747 LOGP(DLAPDM, LOGL_INFO, "k frames outstanding, not sending "
1748 "more (k=%u V(S)=%u V(A)=%u)\n", k, dl->V_send,
1753 /* if we have no tx_hist yet, we create it */
1754 if (!dl->tx_length[dl->V_send]) {
1755 /* Get next message into send-buffer, if any */
1756 if (!dl->send_buffer) {
1759 dl->send_buffer = msgb_dequeue(&dl->send_queue);
1760 /* No more data to be sent */
1761 if (!dl->send_buffer)
1763 LOGP(DLAPDM, LOGL_INFO, "get message from "
1767 /* How much is left in the send-buffer? */
1768 left = msgb_l3len(dl->send_buffer) - dl->send_out;
1769 /* Segment, if data exceeds N201 */
1771 if (length > mctx->n201 - 3)
1772 length = mctx->n201 - 3;
1773 printf("msg-len %d sent %d left %d N201 %d length %d first byte %02x\n", msgb_l3len(dl->send_buffer), dl->send_out, left, mctx->n201, length, dl->send_buffer->l3h[0]);
1774 /* If message in send-buffer is completely sent */
1776 msgb_free(dl->send_buffer);
1777 dl->send_buffer = NULL;
1781 LOGP(DLAPDM, LOGL_INFO, "send I frame %sV(S)=%d\n",
1782 (left > length) ? "segment " : "", dl->V_send);
1784 /* Create I frame (segment) and transmit-buffer content */
1785 msg = msgb_alloc_headroom(23+10, 10, "LAPDm I");
1786 msg->l2h = msgb_put(msg, 3 + length);
1787 msg->l2h[0] = LAPDm_ADDR(LAPDm_LPD_NORMAL, sapi, CR_MS2BS_CMD);
1788 msg->l2h[1] = LAPDm_CTRL_I(dl->V_recv, dl->V_send, 0);
1789 msg->l2h[2] = LAPDm_LEN(length);
1791 msg->l2h[2] |= LAPDm_MORE;
1792 memcpy(msg->l2h + 3, dl->send_buffer->l3h + dl->send_out,
1794 memcpy(dl->tx_hist[dl->V_send], msg->l2h, 3 + length);
1795 dl->tx_length[dl->V_send] = 3 + length;
1796 /* Add length to track how much is already in the tx buffer */
1797 dl->send_out += length;
1799 LOGP(DLAPDM, LOGL_INFO, "resend I frame from tx buffer "
1800 "V(S)=%d\n", dl->V_send);
1802 /* Create I frame (segment) from tx_hist */
1803 length = dl->tx_length[dl->V_send];
1804 msg = msgb_alloc_headroom(23+10, 10, "LAPDm I");
1805 msg->l2h = msgb_put(msg, length);
1806 memcpy(msg->l2h, dl->tx_hist[dl->V_send], length);
1807 msg->l2h[1] = LAPDm_CTRL_I(dl->V_recv, dl->V_send, 0);
1810 /* The value of the send state variable V(S) shall be incremented by 1
1811 * at the end of the transmission of the I frame */
1812 dl->V_send = inc_mod8(dl->V_send);
1814 /* If timer T200 is not running at the time right before transmitting a
1815 * frame, when the PH-READY-TO-SEND primitive is received from the
1816 * physical layer., it shall be set. */
1817 if (!bsc_timer_pending(&dl->t200))
1818 bsc_schedule_timer(&dl->t200, T200);
1820 tx_ph_data_enqueue(dl, msg, chan_nr, link_id, mctx->n201);
1822 rc = 0; /* we sent something */
1826 /* L3 requests suspension of data link */
1827 static int rslms_rx_rll_susp_req(struct msgb *msg, struct lapdm_datalink *dl)
1829 struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
1830 uint8_t sapi = rllh->link_id & 7;
1833 LOGP(DLAPDM, LOGL_ERROR, "SAPI != 0 while suspending\n");
1838 LOGP(DLAPDM, LOGL_INFO, "perform suspension\n");
1840 /* put back the send-buffer to the send-queue (first position) */
1841 if (dl->send_buffer) {
1842 llist_add(&dl->send_buffer->list, &dl->send_queue);
1843 dl->send_buffer = NULL;
1846 /* Clear transmit and send buffer, if any */
1847 lapdm_dl_flush_tx(dl);
1848 lapdm_dl_flush_send(dl);
1852 return send_rll_simple(RSL_MT_SUSP_CONF, &dl->mctx);
1855 /* L3 requests resume of data link */
1856 static int rslms_rx_rll_res_req(struct msgb *msg, struct lapdm_datalink *dl)
1858 struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
1859 uint8_t chan_nr = rllh->chan_nr;
1860 uint8_t link_id = rllh->link_id;
1861 uint8_t sapi = rllh->link_id & 7;
1862 struct tlv_parsed tv;
1864 uint8_t n201 = 23; //FIXME
1866 /* Set chan_nr and link_id for established connection */
1867 memset(&dl->mctx, 0, sizeof(dl->mctx));
1869 dl->mctx.n201 = n201;
1870 dl->mctx.chan_nr = chan_nr;
1871 dl->mctx.link_id = link_id;
1873 rsl_tlv_parse(&tv, rllh->data, msgb_l2len(msg)-sizeof(*rllh));
1874 if (!TLVP_PRESENT(&tv, RSL_IE_L3_INFO)) {
1875 LOGP(DLAPDM, LOGL_ERROR, "resume without message error\n");
1877 return send_rll_simple(RSL_MT_REL_IND, &dl->mctx);
1879 length = TLVP_LEN(&tv, RSL_IE_L3_INFO);
1881 LOGP(DLAPDM, LOGL_INFO, "perform re-establishment (SAMB)\n");
1883 /* Replace message in the send-buffer (reconnect) */
1884 if (dl->send_buffer)
1885 msgb_free(dl->send_buffer);
1887 dl->send_buffer = msg;
1889 /* Discard partly received L3 message */
1890 if (dl->rcv_buffer) {
1891 msgb_free(dl->rcv_buffer);
1892 dl->rcv_buffer = NULL;
1895 /* Create new msgb (old one is now free) */
1896 msg = msgb_alloc_headroom(23+10, 10, "LAPDm SABM");
1897 msg->l2h = msgb_put(msg, 3);
1898 msg->l2h[0] = LAPDm_ADDR(LAPDm_LPD_NORMAL, sapi, CR_MS2BS_CMD);
1899 msg->l2h[1] = LAPDm_CTRL_U(LAPDm_U_SABM, 1);
1900 msg->l2h[2] = LAPDm_LEN(0);
1901 /* Transmit-buffer carries exactly one segment */
1902 memcpy(dl->tx_hist[0], msg->l2h, 3);
1903 dl->tx_length[0] = 3;
1904 /* set Vs to 0, because it is used as index when resending SAMB */
1908 dl->own_busy = dl->peer_busy = 0;
1909 dl->retrans_ctr = 0;
1910 lapdm_dl_newstate(dl, LAPDm_STATE_SABM_SENT);
1912 /* Tramsmit and start T200 */
1913 bsc_schedule_timer(&dl->t200, T200);
1914 return tx_ph_data_enqueue(dl, msg, chan_nr, link_id, n201);
1917 /* L3 requests release of data link */
1918 static int rslms_rx_rll_rel_req(struct msgb *msg, struct lapdm_datalink *dl)
1920 struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
1921 uint8_t chan_nr = rllh->chan_nr;
1922 uint8_t link_id = rllh->link_id;
1923 uint8_t sapi = rllh->link_id & 7;
1926 /* get release mode */
1927 if (rllh->data[0] == RSL_IE_RELEASE_MODE)
1928 mode = rllh->data[1] & 1;
1932 LOGP(DLAPDM, LOGL_INFO, "perform local release\n");
1934 /* reset Timer T200 */
1935 bsc_del_timer(&dl->t200);
1936 /* enter idle state */
1937 lapdm_dl_newstate(dl, LAPDm_STATE_IDLE);
1939 lapdm_dl_flush_tx(dl);
1940 lapdm_dl_flush_send(dl);
1941 /* send notification to L3 */
1942 return send_rll_simple(RSL_MT_REL_CONF, &dl->mctx);
1945 /* in case we are already disconnecting */
1946 if (dl->state == LAPDm_STATE_DISC_SENT)
1949 LOGP(DLAPDM, LOGL_INFO, "perform normal release (DISC)\n");
1952 msgb_pull(msg, msg->tail - msg->l2h);
1954 /* Push LAPDm header on msgb */
1955 msg->l2h = msgb_push(msg, 3);
1956 msg->l2h[0] = LAPDm_ADDR(LAPDm_LPD_NORMAL, sapi, CR_MS2BS_CMD);
1957 msg->l2h[1] = LAPDm_CTRL_U(LAPDm_U_DISC, 1);
1958 msg->l2h[2] = LAPDm_LEN(0);
1959 /* Transmit-buffer carries exactly one segment */
1960 memcpy(dl->tx_hist[0], msg->l2h, 3);
1961 dl->tx_length[0] = 3;
1964 dl->own_busy = dl->peer_busy = 0;
1965 dl->retrans_ctr = 0;
1966 lapdm_dl_newstate(dl, LAPDm_STATE_DISC_SENT);
1968 /* Tramsmit and start T200 */
1969 bsc_schedule_timer(&dl->t200, T200);
1970 return tx_ph_data_enqueue(dl, msg, chan_nr, link_id, dl->mctx.n201);
1973 /* L3 requests release in idle state */
1974 static int rslms_rx_rll_rel_req_idle(struct msgb *msg, struct lapdm_datalink *dl)
1978 /* send notification to L3 */
1979 return send_rll_simple(RSL_MT_REL_CONF, &dl->mctx);
1982 /* L3 requests channel in idle state */
1983 static int rslms_rx_chan_rqd(struct osmocom_ms *ms, struct msgb *msg)
1985 struct abis_rsl_cchan_hdr *cch = msgb_l2(msg);
1988 if (msgb_l2len(msg) < sizeof(*cch) + 4 + 2 + 2) {
1989 LOGP(DRSL, LOGL_ERROR, "Message too short for CHAN RQD!\n");
1992 if (cch->data[0] != RSL_IE_REQ_REFERENCE) {
1993 LOGP(DRSL, LOGL_ERROR, "Missing REQ REFERENCE IE\n");
1996 if (cch->data[4] != RSL_IE_ACCESS_DELAY) {
1997 LOGP(DRSL, LOGL_ERROR, "Missing ACCESS_DELAY IE\n");
2000 if (cch->data[6] != RSL_IE_MS_POWER) {
2001 LOGP(DRSL, LOGL_ERROR, "Missing MS POWER IE\n");
2005 /* TA = 0 - delay */
2006 rc = l1ctl_tx_param_req(ms, 0 - cch->data[5], cch->data[7]);
2008 rc = l1ctl_tx_rach_req(ms, cch->data[1], cch->data[2], cch->data[3]);
2015 /* L1 confirms channel request */
2016 int l2_ph_chan_conf(struct msgb *msg, struct osmocom_ms *ms,
2017 struct l1ctl_info_dl *dl)
2019 struct abis_rsl_cchan_hdr *ch;
2021 struct gsm48_req_ref *ref;
2023 gsm_fn2gsmtime(&tm, htonl(dl->frame_nr));
2026 msg->l2h = msgb_push(msg, sizeof(*ch) + sizeof(*ref));
2027 ch = (struct abis_rsl_cchan_hdr *)msg->l2h;
2028 rsl_init_cchan_hdr(ch, RSL_MT_CHAN_CONF);
2029 ch->chan_nr = RSL_CHAN_RACH;
2030 ch->data[0] = RSL_IE_REQ_REFERENCE;
2031 ref = (struct gsm48_req_ref *) (ch->data + 1);
2034 ref->t3_low = tm.t3 & 0x3;
2035 ref->t3_high = tm.t3 >> 3;
2037 return rslms_sendmsg(msg, ms);
2040 /* Names for Radio Link Layer Management */
2041 static const struct value_string rsl_msg_names[] = {
2042 { RSL_MT_DATA_REQ, "RSL_MT_DATA_REQ" },
2043 { RSL_MT_DATA_IND, "RSL_MT_DATA_IND" },
2044 { RSL_MT_ERROR_IND, "RSL_MT_ERROR_IND" },
2045 { RSL_MT_EST_REQ, "RSL_MT_EST_REQ" },
2046 { RSL_MT_EST_CONF, "RSL_MT_EST_CONF" },
2047 { RSL_MT_EST_IND, "RSL_MT_EST_IND" },
2048 { RSL_MT_EST_IND, "RSL_MT_REL_REQ" },
2049 { RSL_MT_REL_REQ, "RSL_MT_REL_REQ" },
2050 { RSL_MT_REL_CONF, "RSL_MT_REL_CONF" },
2051 { RSL_MT_REL_IND, "RSL_MT_REL_IND" },
2052 { RSL_MT_UNIT_DATA_REQ, "RSL_MT_UNIT_DATA_REQ" },
2053 { RSL_MT_UNIT_DATA_IND, "RSL_MT_UNIT_DATA_IND" },
2054 { RSL_MT_SUSP_REQ, "RSL_MT_SUSP_REQ" },
2055 { RSL_MT_SUSP_CONF, "RSL_MT_SUSP_CONF" },
2056 { RSL_MT_RES_REQ, "RSL_MT_RES_REQ" },
2057 { RSL_MT_RECON_REQ, "RSL_MT_RECON_REQ" },
2058 { RSL_MT_CHAN_RQD, "RSL_MT_CHAN_RQD" },
2059 { RSL_MT_CHAN_CONF, "RSL_MT_CHAN_CONF" },
2063 const char *get_rsl_name(int value)
2065 return get_value_string(rsl_msg_names, value);
2068 const char *lapdm_state_names[] = {
2071 "LAPDm_STATE_SABM_SENT",
2072 "LAPDm_STATE_MF_EST",
2073 "LAPDm_STATE_TIMER_RECOV",
2074 "LAPDm_STATE_DISC_SENT",
2077 /* statefull handling for RSLms RLL messages from L3 */
2078 static struct l2downstate {
2081 int (*rout) (struct msgb *msg, struct lapdm_datalink *dl);
2082 } l2downstatelist[] = {
2083 /* create and send UI command */
2085 RSL_MT_UNIT_DATA_REQ, rslms_rx_rll_udata_req},
2087 /* create and send SABM command */
2088 {SBIT(LAPDm_STATE_IDLE),
2089 RSL_MT_EST_REQ, rslms_rx_rll_est_req},
2091 /* create and send I command */
2092 {SBIT(LAPDm_STATE_MF_EST) |
2093 SBIT(LAPDm_STATE_TIMER_RECOV),
2094 RSL_MT_DATA_REQ, rslms_rx_rll_data_req},
2096 /* suspend datalink */
2097 {SBIT(LAPDm_STATE_MF_EST) |
2098 SBIT(LAPDm_STATE_TIMER_RECOV),
2099 RSL_MT_SUSP_REQ, rslms_rx_rll_susp_req},
2101 /* create and send SABM command (resume) */
2102 {SBIT(LAPDm_STATE_MF_EST) |
2103 SBIT(LAPDm_STATE_TIMER_RECOV),
2104 RSL_MT_RES_REQ, rslms_rx_rll_res_req},
2106 /* create and send SABM command (reconnect) */
2107 {SBIT(LAPDm_STATE_MF_EST) |
2108 SBIT(LAPDm_STATE_TIMER_RECOV),
2109 RSL_MT_RECON_REQ, rslms_rx_rll_res_req},
2111 /* create and send DISC command */
2112 {SBIT(LAPDm_STATE_SABM_SENT) |
2113 SBIT(LAPDm_STATE_MF_EST) |
2114 SBIT(LAPDm_STATE_TIMER_RECOV) |
2115 SBIT(LAPDm_STATE_DISC_SENT),
2116 RSL_MT_REL_REQ, rslms_rx_rll_rel_req},
2118 /* release in idle state */
2119 {SBIT(LAPDm_STATE_IDLE),
2120 RSL_MT_REL_REQ, rslms_rx_rll_rel_req_idle},
2123 #define L2DOWNSLLEN \
2124 (sizeof(l2downstatelist) / sizeof(struct l2downstate))
2126 /* incoming RSLms RLL message from L3 */
2127 static int rslms_rx_rll(struct msgb *msg, struct osmocom_ms *ms)
2129 struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
2130 int msg_type = rllh->c.msg_type;
2131 uint8_t sapi = rllh->link_id & 7;
2132 struct lapdm_entity *le;
2133 struct lapdm_datalink *dl;
2134 int i, supported = 0;
2137 if (msgb_l2len(msg) < sizeof(*rllh)) {
2138 LOGP(DRSL, LOGL_ERROR, "Message too short for RLL hdr!\n");
2142 if (rllh->link_id & 0x40)
2143 le = &ms->l2_entity.lapdm_acch;
2145 le = &ms->l2_entity.lapdm_dcch;
2147 /* G.2.1 No action schall be taken on frames containing an unallocated
2150 dl = datalink_for_sapi(le, sapi);
2152 LOGP(DRSL, LOGL_ERROR, "No instance for SAPI %d!\n", sapi);
2156 LOGP(DRSL, LOGL_INFO, "(ms %s) RLL Message '%s' received in state %s\n",
2157 ms->name, get_rsl_name(msg_type), lapdm_state_names[dl->state]);
2159 /* find function for current state and message */
2160 for (i = 0; i < L2DOWNSLLEN; i++) {
2161 if (msg_type == l2downstatelist[i].type)
2163 if ((msg_type == l2downstatelist[i].type)
2164 && ((1 << dl->state) & l2downstatelist[i].states))
2168 LOGP(DRSL, LOGL_NOTICE, "Message unsupported.\n");
2172 if (i == L2DOWNSLLEN) {
2173 LOGP(DRSL, LOGL_NOTICE, "Message unhandled at this state.\n");
2178 rc = l2downstatelist[i].rout(msg, dl);
2183 /* incoming RSLms COMMON CHANNEL message from L3 */
2184 static int rslms_rx_com_chan(struct msgb *msg, struct osmocom_ms *ms)
2186 struct abis_rsl_cchan_hdr *cch = msgb_l2(msg);
2187 int msg_type = cch->c.msg_type;
2190 if (msgb_l2len(msg) < sizeof(*cch)) {
2191 LOGP(DRSL, LOGL_ERROR, "Message too short for COM CHAN hdr!\n");
2196 case RSL_MT_CHAN_RQD:
2197 /* create and send RACH request */
2198 rc = rslms_rx_chan_rqd(ms, msg);
2201 LOGP(DRSL, LOGL_NOTICE, "Unknown COMMON CHANNEL msg %d!\n",
2210 /* input into layer2 (from layer 3) */
2211 int rslms_recvmsg(struct msgb *msg, struct osmocom_ms *ms)
2213 struct abis_rsl_common_hdr *rslh = msgb_l2(msg);
2216 if (msgb_l2len(msg) < sizeof(*rslh)) {
2217 LOGP(DRSL, LOGL_ERROR, "Message too short RSL hdr!\n");
2221 switch (rslh->msg_discr & 0xfe) {
2222 case ABIS_RSL_MDISC_RLL:
2223 rc = rslms_rx_rll(msg, ms);
2225 case ABIS_RSL_MDISC_COM_CHAN:
2226 rc = rslms_rx_com_chan(msg, ms);
2229 LOGP(DRSL, LOGL_ERROR, "unknown RSLms message "
2230 "discriminator 0x%02x", rslh->msg_discr);
2238 /* input function that L2 calls when sending messages up to L3 */
2239 int rslms_sendmsg(struct msgb *msg, struct osmocom_ms *ms)
2241 if (!ms->l2_entity.msg_handler) {
2246 /* call the layer2 message handler that is registered */
2247 return ms->l2_entity.msg_handler(msg, ms);
2250 /* register message handler for messages that are sent from L2->L3 */
2251 int osmol2_register_handler(struct osmocom_ms *ms, osmol2_cb_t cb)
2253 ms->l2_entity.msg_handler = cb;