--- /dev/null
+/* GSM LAPDm (TS 04.06) implementation */
+
+/* (C) 2010-2011 by Harald Welte <laforge@gnumonks.org>
+ * (C) 2010 by Andreas Eversberg <jolly@eversberg.eu>
+ *
+ * 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.
+ *
+ */
+
+/* Notes on Buffering: rcv_buffer, tx_queue, tx_hist, send_buffer, send_queue
+ *
+ * RX data is stored in the rcv_buffer (pointer). If the message is complete, it
+ * is removed from rcv_buffer pointer and forwarded to L3. If the RX data is
+ * received while there is an incomplete rcv_buffer, it is appended to it.
+ *
+ * TX data is stored in the send_queue first. When transmitting a frame,
+ * the first message in the send_queue is moved to the send_buffer. There it
+ * resides until all fragments are acknowledged. Fragments to be sent by I
+ * frames are stored in the tx_hist buffer for resend, if required. Also the
+ * current fragment is copied into the tx_queue. There it resides until it is
+ * forwarded to layer 1.
+ *
+ * In case we have SAPI 0, we only have a window size of 1, so the unack-
+ * nowledged message resides always in the send_buffer. In case of a suspend,
+ * it can be written back to the first position of the send_queue.
+ *
+ * The layer 1 normally sends a PH-READY-TO-SEND. But because we use
+ * asynchronous transfer between layer 1 and layer 2 (serial link), we must
+ * send a frame before layer 1 reaches the right timeslot to send it. So we
+ * move the tx_queue to layer 1 when there is not already a pending frame, and
+ * wait until acknowledge after the frame has been sent. If we receive an
+ * acknowledge, we can send the next frame from the buffer, if any.
+ *
+ * The moving of tx_queue to layer 1 may also trigger T200, if desired. Also it
+ * will trigger next I frame, if possible.
+ *
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h>
+#include <errno.h>
+#include <arpa/inet.h>
+
+#include <osmocom/core/logging.h>
+#include <osmocom/core/timer.h>
+#include <osmocom/core/msgb.h>
+#include <osmocom/core/utils.h>
+
+#include <osmocom/gsm/tlv.h>
+#include <osmocom/gsm/rsl.h>
+#include <osmocom/gsm/prim.h>
+#include <osmocom/gsm/gsm_utils.h>
+#include <osmocom/gsm/lapdm.h>
+
+#include <osmocom/gsm/protocol/gsm_04_08.h>
+#include <osmocom/gsm/protocol/gsm_08_58.h>
+
+/* TS 04.06 Figure 4 / Section 3.2 */
+#define LAPDm_LPD_NORMAL 0
+#define LAPDm_LPD_SMSCB 1
+#define LAPDm_SAPI_NORMAL 0
+#define LAPDm_SAPI_SMS 3
+#define LAPDm_ADDR(lpd, sapi, cr) ((((lpd) & 0x3) << 5) | (((sapi) & 0x7) << 2) | (((cr) & 0x1) << 1) | 0x1)
+
+#define LAPDm_ADDR_SAPI(addr) (((addr) >> 2) & 0x7)
+#define LAPDm_ADDR_CR(addr) (((addr) >> 1) & 0x1)
+#define LAPDm_ADDR_EA(addr) ((addr) & 0x1)
+
+/* TS 04.06 Table 3 / Section 3.4.3 */
+#define LAPDm_CTRL_I(nr, ns, p) ((((nr) & 0x7) << 5) | (((p) & 0x1) << 4) | (((ns) & 0x7) << 1))
+#define LAPDm_CTRL_S(nr, s, p) ((((nr) & 0x7) << 5) | (((p) & 0x1) << 4) | (((s) & 0x3) << 2) | 0x1)
+#define LAPDm_CTRL_U(u, p) ((((u) & 0x1c) << (5-2)) | (((p) & 0x1) << 4) | (((u) & 0x3) << 2) | 0x3)
+
+#define LAPDm_CTRL_is_I(ctrl) (((ctrl) & 0x1) == 0)
+#define LAPDm_CTRL_is_S(ctrl) (((ctrl) & 0x3) == 1)
+#define LAPDm_CTRL_is_U(ctrl) (((ctrl) & 0x3) == 3)
+
+#define LAPDm_CTRL_U_BITS(ctrl) ((((ctrl) & 0xC) >> 2) | ((ctrl) & 0xE0) >> 3)
+#define LAPDm_CTRL_PF_BIT(ctrl) (((ctrl) >> 4) & 0x1)
+
+#define LAPDm_CTRL_S_BITS(ctrl) (((ctrl) & 0xC) >> 2)
+
+#define LAPDm_CTRL_I_Ns(ctrl) (((ctrl) & 0xE) >> 1)
+#define LAPDm_CTRL_Nr(ctrl) (((ctrl) & 0xE0) >> 5)
+
+/* TS 04.06 Table 4 / Section 3.8.1 */
+#define LAPDm_U_SABM 0x7
+#define LAPDm_U_DM 0x3
+#define LAPDm_U_UI 0x0
+#define LAPDm_U_DISC 0x8
+#define LAPDm_U_UA 0xC
+
+#define LAPDm_S_RR 0x0
+#define LAPDm_S_RNR 0x1
+#define LAPDm_S_REJ 0x2
+
+#define LAPDm_LEN(len) ((len << 2) | 0x1)
+#define LAPDm_MORE 0x2
+
+/* TS 04.06 Section 5.8.3 */
+#define N201_AB_SACCH 18
+#define N201_AB_SDCCH 20
+#define N201_AB_FACCH 20
+#define N201_Bbis 23
+#define N201_Bter_SACCH 21
+#define N201_Bter_SDCCH 23
+#define N201_Bter_FACCH 23
+#define N201_B4 19
+
+/* 5.8.2.1 N200 during establish and release */
+#define N200_EST_REL 5
+/* 5.8.2.1 N200 during timer recovery state */
+#define N200_TR_SACCH 5
+#define N200_TR_SDCCH 23
+#define N200_TR_FACCH_FR 34
+#define N200_TR_EFACCH_FR 48
+#define N200_TR_FACCH_HR 29
+/* FIXME: this depends on chan type */
+#define N200 N200_TR_SACCH
+
+#define CR_MS2BS_CMD 0
+#define CR_MS2BS_RESP 1
+#define CR_BS2MS_CMD 1
+#define CR_BS2MS_RESP 0
+
+/* Set T200 to 1 Second (OpenBTS uses 900ms) */
+#define T200 1, 0
+
+/* k value for each SAPI */
+static uint8_t k_sapi[] = {1, 1, 1, 1, 1, 1, 1, 1};
+
+enum lapdm_format {
+ LAPDm_FMT_A,
+ LAPDm_FMT_B,
+ LAPDm_FMT_Bbis,
+ LAPDm_FMT_Bter,
+ LAPDm_FMT_B4,
+};
+
+static void lapdm_t200_cb(void *data);
+static int rslms_send_i(struct lapdm_msg_ctx *mctx, int line);
+
+/* UTILITY FUNCTIONS */
+
+static inline uint8_t inc_mod8(uint8_t x)
+{
+ return (x + 1) & 7;
+}
+
+static inline uint8_t add_mod8(uint8_t x, uint8_t y)
+{
+ return (x + y) & 7;
+}
+
+static inline uint8_t sub_mod8(uint8_t x, uint8_t y)
+{
+ return (x - y) & 7; /* handle negative results correctly */
+}
+
+static void lapdm_dl_init(struct lapdm_datalink *dl,
+ struct lapdm_entity *entity)
+{
+ memset(dl, 0, sizeof(*dl));
+ INIT_LLIST_HEAD(&dl->send_queue);
+ INIT_LLIST_HEAD(&dl->tx_queue);
+ dl->state = LAPDm_STATE_IDLE;
+ dl->t200.data = dl;
+ dl->t200.cb = &lapdm_t200_cb;
+ dl->entity = entity;
+}
+
+void lapdm_entity_init(struct lapdm_entity *le, enum lapdm_mode mode)
+{
+ unsigned int i;
+
+ for (i = 0; i < ARRAY_SIZE(le->datalink); i++)
+ lapdm_dl_init(&le->datalink[i], le);
+
+ lapdm_entity_set_mode(le, mode);
+}
+
+void lapdm_channel_init(struct lapdm_channel *lc, enum lapdm_mode mode)
+{
+ lapdm_entity_init(&lc->lapdm_acch, mode);
+ lapdm_entity_init(&lc->lapdm_dcch, mode);
+}
+
+
+static void lapdm_dl_flush_send(struct lapdm_datalink *dl)
+{
+ struct msgb *msg;
+
+ /* Flush send-queue */
+ while ((msg = msgb_dequeue(&dl->send_queue)))
+ msgb_free(msg);
+
+ /* Clear send-buffer */
+ if (dl->send_buffer) {
+ msgb_free(dl->send_buffer);
+ dl->send_buffer = NULL;
+ }
+}
+
+static void lapdm_dl_flush_tx(struct lapdm_datalink *dl)
+{
+ struct msgb *msg;
+ unsigned int i;
+
+ while ((msg = msgb_dequeue(&dl->tx_queue)))
+ msgb_free(msg);
+ for (i = 0; i < 8; i++)
+ dl->tx_length[i] = 0;
+}
+
+void lapdm_entity_exit(struct lapdm_entity *le)
+{
+ unsigned int i;
+ struct lapdm_datalink *dl;
+
+ for (i = 0; i < ARRAY_SIZE(le->datalink); i++) {
+ dl = &le->datalink[i];
+ lapdm_dl_flush_tx(dl);
+ lapdm_dl_flush_send(dl);
+ if (dl->rcv_buffer)
+ msgb_free(dl->rcv_buffer);
+ }
+}
+
+void lapdm_channel_exit(struct lapdm_channel *lc)
+{
+ lapdm_entity_exit(&lc->lapdm_acch);
+ lapdm_entity_exit(&lc->lapdm_dcch);
+}
+
+static void lapdm_dl_newstate(struct lapdm_datalink *dl, uint32_t state)
+{
+ LOGP(DLLAPDM, LOGL_INFO, "new state %s -> %s\n",
+ lapdm_state_names[dl->state], lapdm_state_names[state]);
+
+ dl->state = state;
+}
+
+static struct lapdm_datalink *datalink_for_sapi(struct lapdm_entity *le, uint8_t sapi)
+{
+ switch (sapi) {
+ case LAPDm_SAPI_NORMAL:
+ return &le->datalink[0];
+ case LAPDm_SAPI_SMS:
+ return &le->datalink[1];
+ default:
+ return NULL;
+ }
+}
+
+/* remove the L2 header from a MSGB */
+static inline unsigned char *msgb_pull_l2h(struct msgb *msg)
+{
+ unsigned char *ret = msgb_pull(msg, msg->l3h - msg->l2h);
+ msg->l2h = NULL;
+ return ret;
+}
+
+/* Append padding (if required) */
+static void lapdm_pad_msgb(struct msgb *msg, uint8_t n201)
+{
+ int pad_len = n201 - msgb_l2len(msg);
+ uint8_t *data;
+
+ if (pad_len < 0) {
+ LOGP(DLLAPDM, LOGL_ERROR,
+ "cannot pad message that is already too big!\n");
+ return;
+ }
+
+ data = msgb_put(msg, pad_len);
+ memset(data, 0x2B, pad_len);
+}
+
+/* input function that L2 calls when sending messages up to L3 */
+static int rslms_sendmsg(struct msgb *msg, struct lapdm_entity *le)
+{
+ if (!le->l3_cb) {
+ msgb_free(msg);
+ return -EIO;
+ }
+
+ /* call the layer2 message handler that is registered */
+ return le->l3_cb(msg, le, le->l3_ctx);
+}
+
+/* write a frame into the tx queue */
+static int tx_ph_data_enqueue(struct lapdm_datalink *dl, struct msgb *msg,
+ uint8_t chan_nr, uint8_t link_id, uint8_t n201)
+{
+ struct lapdm_entity *le = dl->entity;
+ struct osmo_phsap_prim pp;
+
+ /* if there is a pending message, queue it */
+ if (le->tx_pending || le->flags & LAPDM_ENT_F_POLLING_ONLY) {
+ *msgb_push(msg, 1) = n201;
+ *msgb_push(msg, 1) = link_id;
+ *msgb_push(msg, 1) = chan_nr;
+ msgb_enqueue(&dl->tx_queue, msg);
+ return -EBUSY;
+ }
+
+ osmo_prim_init(&pp.oph, SAP_GSM_PH, PRIM_PH_DATA,
+ PRIM_OP_REQUEST, msg);
+ pp.u.data.chan_nr = chan_nr;
+ pp.u.data.link_id = link_id;
+
+ /* send the frame now */
+ le->tx_pending = 0; /* disabled flow control */
+ lapdm_pad_msgb(msg, n201);
+
+ return le->l1_prim_cb(&pp.oph, le->l1_ctx);
+}
+
+static struct msgb *tx_dequeue_msgb(struct lapdm_entity *le)
+{
+ struct lapdm_datalink *dl;
+ int last = le->last_tx_dequeue;
+ int i = last, n = ARRAY_SIZE(le->datalink);
+ struct msgb *msg = NULL;
+
+ /* round-robin dequeue */
+ do {
+ /* next */
+ i = (i + 1) % n;
+ dl = &le->datalink[i];
+ if ((msg = msgb_dequeue(&dl->tx_queue)))
+ break;
+ } while (i != last);
+
+ if (msg) {
+ /* Set last dequeue position */
+ le->last_tx_dequeue = i;
+ }
+
+ return msg;
+}
+
+/* dequeue a msg that's pending transmission via L1 and wrap it into
+ * a osmo_phsap_prim */
+int lapdm_phsap_dequeue_prim(struct lapdm_entity *le, struct osmo_phsap_prim *pp)
+{
+ struct msgb *msg;
+ uint8_t n201;
+
+ msg = tx_dequeue_msgb(le);
+ if (!msg)
+ return -ENODEV;
+
+ /* if we have a message, send PH-DATA.req */
+ osmo_prim_init(&pp->oph, SAP_GSM_PH, PRIM_PH_DATA,
+ PRIM_OP_REQUEST, msg);
+
+ /* Pull chan_nr and link_id */
+ pp->u.data.chan_nr = *msg->data;
+ msgb_pull(msg, 1);
+ pp->u.data.link_id = *msg->data;
+ msgb_pull(msg, 1);
+ n201 = *msg->data;
+ msgb_pull(msg, 1);
+
+ /* Pad the frame, we can transmit now */
+ lapdm_pad_msgb(msg, n201);
+
+ return 0;
+}
+
+/* get next frame from the tx queue. because the ms has multiple datalinks,
+ * each datalink's queue is read round-robin.
+ */
+static int l2_ph_data_conf(struct msgb *msg, struct lapdm_entity *le)
+{
+ struct osmo_phsap_prim pp;
+
+ /* we may send again */
+ le->tx_pending = 0;
+
+ /* free confirm message */
+ if (msg)
+ msgb_free(msg);
+
+ if (lapdm_phsap_dequeue_prim(le, &pp) < 0) {
+ /* no message in all queues */
+
+ /* If user didn't request PH-EMPTY_FRAME.req, abort */
+ if (!(le->flags & LAPDM_ENT_F_EMPTY_FRAME))
+ return 0;
+
+ /* otherwise, send PH-EMPTY_FRAME.req */
+ osmo_prim_init(&pp.oph, SAP_GSM_PH,
+ PRIM_PH_EMPTY_FRAME,
+ PRIM_OP_REQUEST, NULL);
+ } else {
+ le->tx_pending = 1;
+ }
+
+ return le->l1_prim_cb(&pp.oph, le->l1_ctx);
+}
+
+/* Create RSLms various RSLms messages */
+static int send_rslms_rll_l3(uint8_t msg_type, struct lapdm_msg_ctx *mctx,
+ struct msgb *msg)
+{
+ /* Add the RSL + RLL header */
+ rsl_rll_push_l3(msg, msg_type, mctx->chan_nr, mctx->link_id, 1);
+
+ /* send off the RSLms message to L3 */
+ return rslms_sendmsg(msg, mctx->dl->entity);
+}
+
+/* Take a B4 format message from L1 and create RSLms UNIT DATA IND */
+static int send_rslms_rll_l3_ui(struct lapdm_msg_ctx *mctx, struct msgb *msg)
+{
+ uint8_t l3_len = msg->tail - (uint8_t *)msgb_l3(msg);
+ struct abis_rsl_rll_hdr *rllh;
+
+ /* Add the RSL + RLL header */
+ msgb_tv16_push(msg, RSL_IE_L3_INFO, l3_len);
+ msgb_push(msg, 2 + 2);
+ rsl_rll_push_hdr(msg, RSL_MT_UNIT_DATA_IND, mctx->chan_nr,
+ mctx->link_id, 1);
+ rllh = (struct abis_rsl_rll_hdr *)msgb_l2(msg);
+
+ rllh->data[0] = RSL_IE_TIMING_ADVANCE;
+ rllh->data[1] = mctx->ta_ind;
+
+ rllh->data[2] = RSL_IE_MS_POWER;
+ rllh->data[3] = mctx->tx_power_ind;
+
+ return rslms_sendmsg(msg, mctx->dl->entity);
+}
+
+static int send_rll_simple(uint8_t msg_type, struct lapdm_msg_ctx *mctx)
+{
+ struct msgb *msg;
+
+ msg = rsl_rll_simple(msg_type, mctx->chan_nr, mctx->link_id, 1);
+
+ /* send off the RSLms message to L3 */
+ return rslms_sendmsg(msg, mctx->dl->entity);
+}
+
+static int rsl_rll_error(uint8_t cause, struct lapdm_msg_ctx *mctx)
+{
+ struct msgb *msg;
+
+ LOGP(DLLAPDM, LOGL_NOTICE, "sending MDL-ERROR-IND %d\n", cause);
+ msg = rsl_rll_simple(RSL_MT_ERROR_IND, mctx->chan_nr, mctx->link_id, 1);
+ msg->l2h = msgb_put(msg, sizeof(struct abis_rsl_rll_hdr));
+ msgb_tlv_put(msg, RSL_IE_RLM_CAUSE, 1, &cause);
+ return rslms_sendmsg(msg, mctx->dl->entity);
+}
+
+static int check_length_ind(struct lapdm_msg_ctx *mctx, uint8_t length_ind)
+{
+ if (!(length_ind & 0x01)) {
+ /* G.4.1 If the EL bit is set to "0", an MDL-ERROR-INDICATION
+ * primitive with cause "frame not implemented" is sent to the
+ * mobile management entity. */
+ LOGP(DLLAPDM, LOGL_NOTICE,
+ "we don't support multi-octet length\n");
+ rsl_rll_error(RLL_CAUSE_FRM_UNIMPL, mctx);
+ return -EINVAL;
+ }
+ return 0;
+}
+
+static int lapdm_send_resend(struct lapdm_datalink *dl)
+{
+ struct msgb *msg = msgb_alloc_headroom(23+10, 10, "LAPDm resend");
+ int length;
+
+ /* Resend SABM/DISC from tx_hist */
+ length = dl->tx_length[0];
+ msg->l2h = msgb_put(msg, length);
+ memcpy(msg->l2h, dl->tx_hist[dl->V_send], length);
+
+ return tx_ph_data_enqueue(dl, msg, dl->mctx.chan_nr, dl->mctx.link_id,
+ dl->mctx.n201);
+}
+
+static int lapdm_send_ua(struct lapdm_msg_ctx *mctx, uint8_t len, uint8_t *data)
+{
+ uint8_t sapi = mctx->link_id & 7;
+ uint8_t f_bit = LAPDm_CTRL_PF_BIT(mctx->ctrl);
+ struct msgb *msg = msgb_alloc_headroom(23+10, 10, "LAPDm UA");
+ struct lapdm_entity *le = mctx->dl->entity;
+
+ msg->l2h = msgb_put(msg, 3 + len);
+ msg->l2h[0] = LAPDm_ADDR(LAPDm_LPD_NORMAL, sapi, le->cr.loc2rem.resp);
+ msg->l2h[1] = LAPDm_CTRL_U(LAPDm_U_UA, f_bit);
+ msg->l2h[2] = LAPDm_LEN(len);
+ if (len)
+ memcpy(msg->l2h + 3, data, len);
+
+ return tx_ph_data_enqueue(mctx->dl, msg, mctx->chan_nr, mctx->link_id,
+ mctx->n201);
+}
+
+static int lapdm_send_dm(struct lapdm_msg_ctx *mctx)
+{
+ uint8_t sapi = mctx->link_id & 7;
+ uint8_t f_bit = LAPDm_CTRL_PF_BIT(mctx->ctrl);
+ struct msgb *msg = msgb_alloc_headroom(23+10, 10, "LAPDm DM");
+ struct lapdm_entity *le = mctx->dl->entity;
+
+ msg->l2h = msgb_put(msg, 3);
+ msg->l2h[0] = LAPDm_ADDR(LAPDm_LPD_NORMAL, sapi, le->cr.loc2rem.resp);
+ msg->l2h[1] = LAPDm_CTRL_U(LAPDm_U_DM, f_bit);
+ msg->l2h[2] = 0;
+
+ return tx_ph_data_enqueue(mctx->dl, msg, mctx->chan_nr, mctx->link_id,
+ mctx->n201);
+}
+
+static int lapdm_send_rr(struct lapdm_msg_ctx *mctx, uint8_t f_bit)
+{
+ uint8_t sapi = mctx->link_id & 7;
+ struct msgb *msg = msgb_alloc_headroom(23+10, 10, "LAPDm RR");
+ struct lapdm_entity *le = mctx->dl->entity;
+
+ msg->l2h = msgb_put(msg, 3);
+ msg->l2h[0] = LAPDm_ADDR(LAPDm_LPD_NORMAL, sapi, le->cr.loc2rem.resp);
+ msg->l2h[1] = LAPDm_CTRL_S(mctx->dl->V_recv, LAPDm_S_RR, f_bit);
+ msg->l2h[2] = LAPDm_LEN(0);
+
+ return tx_ph_data_enqueue(mctx->dl, msg, mctx->chan_nr, mctx->link_id,
+ mctx->n201);
+}
+
+static int lapdm_send_rnr(struct lapdm_msg_ctx *mctx, uint8_t f_bit)
+{
+ uint8_t sapi = mctx->link_id & 7;
+ struct msgb *msg = msgb_alloc_headroom(23+10, 10, "LAPDm RNR");
+ struct lapdm_entity *le = mctx->dl->entity;
+
+ msg->l2h = msgb_put(msg, 3);
+ msg->l2h[0] = LAPDm_ADDR(LAPDm_LPD_NORMAL, sapi, le->cr.loc2rem.resp);
+ msg->l2h[1] = LAPDm_CTRL_S(mctx->dl->V_recv, LAPDm_S_RNR, f_bit);
+ msg->l2h[2] = LAPDm_LEN(0);
+
+ return tx_ph_data_enqueue(mctx->dl, msg, mctx->chan_nr, mctx->link_id,
+ mctx->n201);
+}
+
+static int lapdm_send_rej(struct lapdm_msg_ctx *mctx, uint8_t f_bit)
+{
+ uint8_t sapi = mctx->link_id & 7;
+ struct msgb *msg = msgb_alloc_headroom(23+10, 10, "LAPDm REJ");
+ struct lapdm_entity *le = mctx->dl->entity;
+
+ msg->l2h = msgb_put(msg, 3);
+ msg->l2h[0] = LAPDm_ADDR(LAPDm_LPD_NORMAL, sapi, le->cr.loc2rem.resp);
+ msg->l2h[1] = LAPDm_CTRL_S(mctx->dl->V_recv, LAPDm_S_REJ, f_bit);
+ msg->l2h[2] = LAPDm_LEN(0);
+
+ return tx_ph_data_enqueue(mctx->dl, msg, mctx->chan_nr, mctx->link_id,
+ mctx->n201);
+}
+
+/* Timer callback on T200 expiry */
+static void lapdm_t200_cb(void *data)
+{
+ struct lapdm_datalink *dl = data;
+
+ LOGP(DLLAPDM, LOGL_INFO, "lapdm_t200_cb(%p) state=%u\n", dl, dl->state);
+
+ switch (dl->state) {
+ case LAPDm_STATE_SABM_SENT:
+ /* 5.4.1.3 */
+ if (dl->retrans_ctr + 1 >= N200_EST_REL + 1) {
+ /* send RELEASE INDICATION to L3 */
+ send_rll_simple(RSL_MT_REL_IND, &dl->mctx);
+ /* send MDL ERROR INIDCATION to L3 */
+ rsl_rll_error(RLL_CAUSE_T200_EXPIRED, &dl->mctx);
+ /* flush tx buffers */
+ lapdm_dl_flush_tx(dl);
+ /* go back to idle state */
+ lapdm_dl_newstate(dl, LAPDm_STATE_IDLE);
+ /* NOTE: we must not change any other states or buffers
+ * and queues, since we may reconnect after handover
+ * failure. the buffered messages is replaced there */
+ break;
+ }
+ /* retransmit SABM command */
+ lapdm_send_resend(dl);
+ /* increment re-transmission counter */
+ dl->retrans_ctr++;
+ /* restart T200 (PH-READY-TO-SEND) */
+ osmo_timer_schedule(&dl->t200, T200);
+ break;
+ case LAPDm_STATE_DISC_SENT:
+ /* 5.4.4.3 */
+ if (dl->retrans_ctr + 1 >= N200_EST_REL + 1) {
+ /* send RELEASE INDICATION to L3 */
+ send_rll_simple(RSL_MT_REL_CONF, &dl->mctx);
+ /* send MDL ERROR INIDCATION to L3 */
+ rsl_rll_error(RLL_CAUSE_T200_EXPIRED, &dl->mctx);
+ /* flush buffers */
+ lapdm_dl_flush_tx(dl);
+ lapdm_dl_flush_send(dl);
+ /* go back to idle state */
+ lapdm_dl_newstate(dl, LAPDm_STATE_IDLE);
+ /* NOTE: we must not change any other states or buffers
+ * and queues, since we may reconnect after handover
+ * failure. the buffered messages is replaced there */
+ break;
+ }
+ /* retransmit DISC command */
+ lapdm_send_resend(dl);
+ /* increment re-transmission counter */
+ dl->retrans_ctr++;
+ /* restart T200 (PH-READY-TO-SEND) */
+ osmo_timer_schedule(&dl->t200, T200);
+ break;
+ case LAPDm_STATE_MF_EST:
+ /* 5.5.7 */
+ dl->retrans_ctr = 0;
+ lapdm_dl_newstate(dl, LAPDm_STATE_TIMER_RECOV);
+ /* fall through */
+ case LAPDm_STATE_TIMER_RECOV:
+ dl->retrans_ctr++;
+ if (dl->retrans_ctr < N200) {
+ /* retransmit I frame (V_s-1) with P=1, if any */
+ if (dl->tx_length[sub_mod8(dl->V_send, 1)]) {
+ struct msgb *msg;
+ int length;
+
+ LOGP(DLLAPDM, LOGL_INFO, "retransmit last frame "
+ "V(S)=%d\n", sub_mod8(dl->V_send, 1));
+ /* Create I frame (segment) from tx_hist */
+ length = dl->tx_length[sub_mod8(dl->V_send, 1)];
+ msg = msgb_alloc_headroom(23+10, 10, "LAPDm I");
+ msg->l2h = msgb_put(msg, length);
+ memcpy(msg->l2h,
+ dl->tx_hist[sub_mod8(dl->V_send, 1)],
+ length);
+ msg->l2h[1] = LAPDm_CTRL_I(dl->V_recv,
+ sub_mod8(dl->V_send, 1), 1); /* P=1 */
+ tx_ph_data_enqueue(dl, msg, dl->mctx.chan_nr,
+ dl->mctx.link_id, dl->mctx.n201);
+ } else {
+ /* OR send appropriate supervision frame with P=1 */
+ if (!dl->own_busy && !dl->seq_err_cond) {
+ lapdm_send_rr(&dl->mctx, 1);
+ /* NOTE: In case of sequence error
+ * condition, the REJ frame has been
+ * transmitted when entering the
+ * condition, so it has not be done
+ * here
+ */
+ } else if (dl->own_busy) {
+ lapdm_send_rnr(&dl->mctx, 1);
+ } else {
+ LOGP(DLLAPDM, LOGL_INFO, "unhandled, "
+ "pls. fix\n");
+ }
+ }
+ /* restart T200 (PH-READY-TO-SEND) */
+ osmo_timer_schedule(&dl->t200, T200);
+ } else {
+ /* send MDL ERROR INIDCATION to L3 */
+ rsl_rll_error(RLL_CAUSE_T200_EXPIRED, &dl->mctx);
+ }
+ break;
+ default:
+ LOGP(DLLAPDM, LOGL_INFO, "T200 expired in unexpected "
+ "dl->state %u\n", dl->state);
+ }
+}
+
+/* 5.5.3.1: Common function to acknowlege frames up to the given N(R) value */
+static void lapdm_acknowledge(struct lapdm_msg_ctx *mctx)
+{
+ struct lapdm_datalink *dl = mctx->dl;
+ uint8_t nr = LAPDm_CTRL_Nr(mctx->ctrl);
+ int s = 0, rej = 0, t200_reset = 0;
+ int i;
+
+ /* supervisory frame ? */
+ if (LAPDm_CTRL_is_S(mctx->ctrl))
+ s = 1;
+ /* REJ frame ? */
+ if (s && LAPDm_CTRL_S_BITS(mctx->ctrl) == LAPDm_S_REJ)
+ rej = 1;
+
+ /* Flush all transmit buffers of acknowledged frames */
+ for (i = dl->V_ack; i != nr; i = inc_mod8(i)) {
+ if (dl->tx_length[i]) {
+ dl->tx_length[i] = 0;
+ LOGP(DLLAPDM, LOGL_INFO, "ack frame %d\n", i);
+ }
+ }
+
+ if (dl->state != LAPDm_STATE_TIMER_RECOV) {
+ /* When not in the timer recovery condition, the data
+ * link layer entity shall reset the timer T200 on
+ * receipt of a valid I frame with N(R) higher than V(A),
+ * or an REJ with an N(R) equal to V(A). */
+ if ((!rej && nr != dl->V_ack)
+ || (rej && nr == dl->V_ack)) {
+ LOGP(DLLAPDM, LOGL_INFO, "reset t200\n");
+ t200_reset = 1;
+ osmo_timer_del(&dl->t200);
+ /* 5.5.3.1 Note 1 + 2 imply timer recovery cond. */
+ }
+ /* 5.7.4: N(R) sequence error
+ * N(R) is called valid, if and only if
+ * (N(R)-V(A)) mod 8 <= (V(S)-V(A)) mod 8.
+ */
+ if (sub_mod8(nr, dl->V_ack) > sub_mod8(dl->V_send, dl->V_ack)) {
+ LOGP(DLLAPDM, LOGL_NOTICE, "N(R) sequence error\n");
+ rsl_rll_error(RLL_CAUSE_SEQ_ERR, mctx);
+ }
+ }
+
+ /* V(A) shall be set to the value of N(R) */
+ dl->V_ack = nr;
+
+ /* If T200 has been reset by the receipt of an I, RR or RNR frame,
+ * and if there are outstanding I frames, restart T200 */
+ if (t200_reset && !rej) {
+ if (dl->tx_length[dl->V_send - 1]) {
+ LOGP(DLLAPDM, LOGL_INFO, "start T200, due to unacked I "
+ "frame(s)\n");
+ osmo_timer_schedule(&dl->t200, T200);
+ }
+ }
+}
+
+/* L1 -> L2 */
+
+/* Receive a LAPDm U (Unnumbered) message from L1 */
+static int lapdm_rx_u(struct msgb *msg, struct lapdm_msg_ctx *mctx)
+{
+ struct lapdm_datalink *dl = mctx->dl;
+ struct lapdm_entity *le = dl->entity;
+ uint8_t length;
+ int rc;
+ int rsl_msg;
+
+ switch (LAPDm_CTRL_U_BITS(mctx->ctrl)) {
+ case LAPDm_U_SABM:
+ rsl_msg = RSL_MT_EST_IND;
+
+ LOGP(DLLAPDM, LOGL_INFO, "SABM received\n");
+ /* 5.7.1 */
+ dl->seq_err_cond = 0;
+ /* G.2.2 Wrong value of the C/R bit */
+ if (LAPDm_ADDR_CR(mctx->addr) == le->cr.rem2loc.resp) {
+ LOGP(DLLAPDM, LOGL_NOTICE, "SABM response error\n");
+ msgb_free(msg);
+ rsl_rll_error(RLL_CAUSE_FRM_UNIMPL, mctx);
+ return -EINVAL;
+ }
+
+ length = msg->l2h[2] >> 2;
+ /* G.4.5 If SABM is received with L>N201 or with M bit
+ * set, AN MDL-ERROR-INDICATION is sent to MM.
+ */
+ if ((msg->l2h[2] & LAPDm_MORE) || length + 3 > mctx->n201) {
+ LOGP(DLLAPDM, LOGL_NOTICE, "SABM too large error\n");
+ msgb_free(msg);
+ rsl_rll_error(RLL_CAUSE_UFRM_INC_PARAM, mctx);
+ return -EIO;
+ }
+
+ /* Must be Format B */
+ rc = check_length_ind(mctx, msg->l2h[2]);
+ if (rc < 0) {
+ msgb_free(msg);
+ return rc;
+ }
+ switch (dl->state) {
+ case LAPDm_STATE_IDLE:
+ /* Set chan_nr and link_id for established connection */
+ memset(&dl->mctx, 0, sizeof(dl->mctx));
+ dl->mctx.dl = dl;
+ dl->mctx.chan_nr = mctx->chan_nr;
+ dl->mctx.link_id = mctx->link_id;
+ dl->mctx.n201 = mctx->n201;
+ break;
+ case LAPDm_STATE_MF_EST:
+ if (length == 0) {
+ rsl_msg = RSL_MT_EST_CONF;
+ break;
+ }
+ LOGP(DLLAPDM, LOGL_INFO, "SABM command, multiple "
+ "frame established state\n");
+ /* check for contention resoultion */
+ if (dl->tx_hist[0][2] >> 2) {
+ LOGP(DLLAPDM, LOGL_NOTICE, "SABM not allowed "
+ "during contention resolution\n");
+ rsl_rll_error(RLL_CAUSE_SABM_INFO_NOTALL, mctx);
+ }
+ msgb_free(msg);
+ return 0;
+ case LAPDm_STATE_DISC_SENT:
+ /* 5.4.6.2 send DM with F=P */
+ lapdm_send_dm(mctx);
+ /* reset Timer T200 */
+ osmo_timer_del(&dl->t200);
+ msgb_free(msg);
+ return send_rll_simple(RSL_MT_REL_CONF, mctx);
+ default:
+ lapdm_send_ua(mctx, length, msg->l2h + 3);
+ msgb_free(msg);
+ return 0;
+ }
+ /* send UA response */
+ lapdm_send_ua(mctx, length, msg->l2h + 3);
+ /* set Vs, Vr and Va to 0 */
+ dl->V_send = dl->V_recv = dl->V_ack = 0;
+ /* clear tx_hist */
+ dl->tx_length[0] = 0;
+ /* enter multiple-frame-established state */
+ lapdm_dl_newstate(dl, LAPDm_STATE_MF_EST);
+ /* send notification to L3 */
+ if (length == 0) {
+ /* 5.4.1.2 Normal establishment procedures */
+ rc = send_rll_simple(rsl_msg, mctx);
+ msgb_free(msg);
+ } else {
+ /* 5.4.1.4 Contention resolution establishment */
+ msg->l3h = msg->l2h + 3;
+ msgb_pull_l2h(msg);
+ rc = send_rslms_rll_l3(rsl_msg, mctx, msg);
+ }
+ break;
+ case LAPDm_U_DM:
+ LOGP(DLLAPDM, LOGL_INFO, "DM received\n");
+ /* G.2.2 Wrong value of the C/R bit */
+ if (LAPDm_ADDR_CR(mctx->addr) == le->cr.rem2loc.cmd) {
+ LOGP(DLLAPDM, LOGL_NOTICE, "DM command error\n");
+ msgb_free(msg);
+ rsl_rll_error(RLL_CAUSE_FRM_UNIMPL, mctx);
+ return -EINVAL;
+ }
+ if (!LAPDm_CTRL_PF_BIT(mctx->ctrl)) {
+ /* 5.4.1.2 DM responses with the F bit set to "0"
+ * shall be ignored.
+ */
+ msgb_free(msg);
+ return 0;
+ }
+ switch (dl->state) {
+ case LAPDm_STATE_SABM_SENT:
+ break;
+ case LAPDm_STATE_MF_EST:
+ if (LAPDm_CTRL_PF_BIT(mctx->ctrl) == 1) {
+ LOGP(DLLAPDM, LOGL_INFO, "unsolicited DM "
+ "response\n");
+ rsl_rll_error(RLL_CAUSE_UNSOL_DM_RESP, mctx);
+ } else {
+ LOGP(DLLAPDM, LOGL_INFO, "unsolicited DM "
+ "response, multiple frame established "
+ "state\n");
+ rsl_rll_error(RLL_CAUSE_UNSOL_DM_RESP_MF, mctx);
+ }
+ msgb_free(msg);
+ return 0;
+ case LAPDm_STATE_TIMER_RECOV:
+ /* DM is normal in case PF = 1 */
+ if (LAPDm_CTRL_PF_BIT(mctx->ctrl) == 0) {
+ LOGP(DLLAPDM, LOGL_INFO, "unsolicited DM "
+ "response, multiple frame established "
+ "state\n");
+ rsl_rll_error(RLL_CAUSE_UNSOL_DM_RESP_MF, mctx);
+ msgb_free(msg);
+ return 0;
+ }
+ break;
+ case LAPDm_STATE_DISC_SENT:
+ /* reset Timer T200 */
+ osmo_timer_del(&dl->t200);
+ /* go to idle state */
+ lapdm_dl_newstate(dl, LAPDm_STATE_IDLE);
+ rc = send_rll_simple(RSL_MT_REL_CONF, mctx);
+ msgb_free(msg);
+ return 0;
+ case LAPDm_STATE_IDLE:
+ /* 5.4.5 all other frame types shall be discarded */
+ default:
+ LOGP(DLLAPDM, LOGL_INFO, "unsolicited DM response! "
+ "(discarding)\n");
+ msgb_free(msg);
+ return 0;
+ }
+ /* reset T200 */
+ osmo_timer_del(&dl->t200);
+ rc = send_rll_simple(RSL_MT_REL_IND, mctx);
+ msgb_free(msg);
+ break;
+ case LAPDm_U_UI:
+ LOGP(DLLAPDM, LOGL_INFO, "UI received\n");
+ /* G.2.2 Wrong value of the C/R bit */
+ if (LAPDm_ADDR_CR(mctx->addr) == le->cr.rem2loc.resp) {
+ LOGP(DLLAPDM, LOGL_NOTICE, "UI indicates response "
+ "error\n");
+ msgb_free(msg);
+ rsl_rll_error(RLL_CAUSE_FRM_UNIMPL, mctx);
+ return -EINVAL;
+ }
+
+ length = msg->l2h[2] >> 2;
+ /* FIXME: G.4.5 If UI is received with L>N201 or with M bit
+ * set, AN MDL-ERROR-INDICATION is sent to MM.
+ */
+
+ if (mctx->lapdm_fmt == LAPDm_FMT_B4) {
+ length = N201_B4;
+ msg->l3h = msg->l2h + 2;
+ } else {
+ rc = check_length_ind(mctx, msg->l2h[2]);
+ if (rc < 0) {
+ msgb_free(msg);
+ return rc;
+ }
+ length = msg->l2h[2] >> 2;
+ msg->l3h = msg->l2h + 3;
+ }
+ /* do some length checks */
+ if (length == 0) {
+ /* 5.3.3 UI frames received with the length indicator
+ * set to "0" shall be ignored
+ */
+ LOGP(DLLAPDM, LOGL_INFO, "length=0 (discarding)\n");
+ msgb_free(msg);
+ return 0;
+ }
+ switch (LAPDm_ADDR_SAPI(mctx->addr)) {
+ case LAPDm_SAPI_NORMAL:
+ case LAPDm_SAPI_SMS:
+ break;
+ default:
+ /* 5.3.3 UI frames with invalid SAPI values shall be
+ * discarded
+ */
+ LOGP(DLLAPDM, LOGL_INFO, "sapi=%u (discarding)\n",
+ LAPDm_ADDR_SAPI(mctx->addr));
+ msgb_free(msg);
+ return 0;
+ }
+ msgb_pull_l2h(msg);
+ rc = send_rslms_rll_l3_ui(mctx, msg);
+ break;
+ case LAPDm_U_DISC:
+ rsl_msg = RSL_MT_REL_IND;
+
+ LOGP(DLLAPDM, LOGL_INFO, "DISC received\n");
+ /* flush buffers */
+ lapdm_dl_flush_tx(dl);
+ lapdm_dl_flush_send(dl);
+ /* 5.7.1 */
+ dl->seq_err_cond = 0;
+ /* G.2.2 Wrong value of the C/R bit */
+ if (LAPDm_ADDR_CR(mctx->addr) == le->cr.rem2loc.resp) {
+ LOGP(DLLAPDM, LOGL_NOTICE, "DISC response error\n");
+ msgb_free(msg);
+ rsl_rll_error(RLL_CAUSE_FRM_UNIMPL, mctx);
+ return -EINVAL;
+ }
+ length = msg->l2h[2] >> 2;
+ if (length > 0 || msg->l2h[2] & 0x02) {
+ /* G.4.4 If a DISC or DM frame is received with L>0 or
+ * with the M bit set to "1", an MDL-ERROR-INDICATION
+ * primitive with cause "U frame with incorrect
+ * parameters" is sent to the mobile management entity.
+ */
+ LOGP(DLLAPDM, LOGL_NOTICE,
+ "U frame iwth incorrect parameters ");
+ msgb_free(msg);
+ rsl_rll_error(RLL_CAUSE_UFRM_INC_PARAM, mctx);
+ return -EIO;
+ }
+ switch (dl->state) {
+ case LAPDm_STATE_IDLE:
+ LOGP(DLLAPDM, LOGL_INFO, "DISC in idle state\n");
+ /* send DM with F=P */
+ msgb_free(msg);
+ return lapdm_send_dm(mctx);
+ case LAPDm_STATE_SABM_SENT:
+ LOGP(DLLAPDM, LOGL_INFO, "DISC in SABM state\n");
+ /* 5.4.6.2 send DM with F=P */
+ lapdm_send_dm(mctx);
+ /* reset Timer T200 */
+ osmo_timer_del(&dl->t200);
+ msgb_free(msg);
+ return send_rll_simple(RSL_MT_REL_IND, mctx);
+ case LAPDm_STATE_MF_EST:
+ case LAPDm_STATE_TIMER_RECOV:
+ LOGP(DLLAPDM, LOGL_INFO, "DISC in est state\n");
+ break;
+ case LAPDm_STATE_DISC_SENT:
+ LOGP(DLLAPDM, LOGL_INFO, "DISC in disc state\n");
+ rsl_msg = RSL_MT_REL_CONF;
+ break;
+ default:
+ lapdm_send_ua(mctx, length, msg->l2h + 3);
+ msgb_free(msg);
+ return 0;
+ }
+ /* send UA response */
+ lapdm_send_ua(mctx, length, msg->l2h + 3);
+ /* reset Timer T200 */
+ osmo_timer_del(&dl->t200);
+ /* enter idle state */
+ lapdm_dl_newstate(dl, LAPDm_STATE_IDLE);
+ /* send notification to L3 */
+ rc = send_rll_simple(rsl_msg, mctx);
+ msgb_free(msg);
+ break;
+ case LAPDm_U_UA:
+ LOGP(DLLAPDM, LOGL_INFO, "UA received\n");
+ /* G.2.2 Wrong value of the C/R bit */
+ if (LAPDm_ADDR_CR(mctx->addr) == le->cr.rem2loc.cmd) {
+ LOGP(DLLAPDM, LOGL_NOTICE, "UA indicates command "
+ "error\n");
+ msgb_free(msg);
+ rsl_rll_error(RLL_CAUSE_FRM_UNIMPL, mctx);
+ return -EINVAL;
+ }
+
+ length = msg->l2h[2] >> 2;
+ /* G.4.5 If UA is received with L>N201 or with M bit
+ * set, AN MDL-ERROR-INDICATION is sent to MM.
+ */
+ if ((msg->l2h[2] & LAPDm_MORE) || length + 3 > mctx->n201) {
+ LOGP(DLLAPDM, LOGL_NOTICE, "UA too large error\n");
+ msgb_free(msg);
+ rsl_rll_error(RLL_CAUSE_UFRM_INC_PARAM, mctx);
+ return -EIO;
+ }
+
+ if (!LAPDm_CTRL_PF_BIT(mctx->ctrl)) {
+ /* 5.4.1.2 A UA response with the F bit set to "0"
+ * shall be ignored.
+ */
+ LOGP(DLLAPDM, LOGL_INFO, "F=0 (discarding)\n");
+ msgb_free(msg);
+ return 0;
+ }
+ switch (dl->state) {
+ case LAPDm_STATE_SABM_SENT:
+ break;
+ case LAPDm_STATE_MF_EST:
+ case LAPDm_STATE_TIMER_RECOV:
+ LOGP(DLLAPDM, LOGL_INFO, "unsolicited UA response! "
+ "(discarding)\n");
+ rsl_rll_error(RLL_CAUSE_UNSOL_UA_RESP, mctx);
+ msgb_free(msg);
+ return 0;
+ case LAPDm_STATE_DISC_SENT:
+ LOGP(DLLAPDM, LOGL_INFO, "UA in disconnect state\n");
+ /* reset Timer T200 */
+ osmo_timer_del(&dl->t200);
+ /* go to idle state */
+ lapdm_dl_newstate(dl, LAPDm_STATE_IDLE);
+ rc = send_rll_simple(RSL_MT_REL_CONF, mctx);
+ msgb_free(msg);
+ return 0;
+ case LAPDm_STATE_IDLE:
+ /* 5.4.5 all other frame types shall be discarded */
+ default:
+ LOGP(DLLAPDM, LOGL_INFO, "unsolicited UA response! "
+ "(discarding)\n");
+ msgb_free(msg);
+ return 0;
+ }
+ LOGP(DLLAPDM, LOGL_INFO, "UA in SABM state\n");
+ /* reset Timer T200 */
+ osmo_timer_del(&dl->t200);
+ /* compare UA with SABME if contention resolution is applied */
+ if (dl->tx_hist[0][2] >> 2) {
+ rc = check_length_ind(mctx, msg->l2h[2]);
+ if (rc < 0) {
+ rc = send_rll_simple(RSL_MT_REL_IND, mctx);
+ msgb_free(msg);
+ /* go to idle state */
+ lapdm_dl_newstate(dl, LAPDm_STATE_IDLE);
+ return 0;
+ }
+ length = msg->l2h[2] >> 2;
+ if (length != (dl->tx_hist[0][2] >> 2)
+ || !!memcmp(dl->tx_hist[0] + 3, msg->l2h + 3,
+ length)) {
+ LOGP(DLLAPDM, LOGL_INFO, "**** UA response "
+ "mismatches ****\n");
+ rc = send_rll_simple(RSL_MT_REL_IND, mctx);
+ msgb_free(msg);
+ /* go to idle state */
+ lapdm_dl_newstate(dl, LAPDm_STATE_IDLE);
+ return 0;
+ }
+ }
+ /* set Vs, Vr and Va to 0 */
+ dl->V_send = dl->V_recv = dl->V_ack = 0;
+ /* clear tx_hist */
+ dl->tx_length[0] = 0;
+ /* enter multiple-frame-established state */
+ lapdm_dl_newstate(dl, LAPDm_STATE_MF_EST);
+ /* send outstanding frames, if any (resume / reconnect) */
+ rslms_send_i(mctx, __LINE__);
+ /* send notification to L3 */
+ rc = send_rll_simple(RSL_MT_EST_CONF, mctx);
+ msgb_free(msg);
+ break;
+ default:
+ /* G.3.1 */
+ LOGP(DLLAPDM, LOGL_NOTICE, "Unnumbered frame not allowed.\n");
+ msgb_free(msg);
+ rsl_rll_error(RLL_CAUSE_FRM_UNIMPL, mctx);
+ return -EINVAL;
+ }
+ return rc;
+}
+
+/* Receive a LAPDm S (Supervisory) message from L1 */
+static int lapdm_rx_s(struct msgb *msg, struct lapdm_msg_ctx *mctx)
+{
+ struct lapdm_datalink *dl = mctx->dl;
+ struct lapdm_entity *le = dl->entity;
+ uint8_t length;
+
+ length = msg->l2h[2] >> 2;
+ if (length > 0 || msg->l2h[2] & 0x02) {
+ /* G.4.3 If a supervisory frame is received with L>0 or
+ * with the M bit set to "1", an MDL-ERROR-INDICATION
+ * primitive with cause "S frame with incorrect
+ * parameters" is sent to the mobile management entity. */
+ LOGP(DLLAPDM, LOGL_NOTICE,
+ "S frame with incorrect parameters\n");
+ msgb_free(msg);
+ rsl_rll_error(RLL_CAUSE_SFRM_INC_PARAM, mctx);
+ return -EIO;
+ }
+
+ if (LAPDm_ADDR_CR(mctx->addr) == le->cr.rem2loc.resp
+ && LAPDm_CTRL_PF_BIT(mctx->ctrl)
+ && dl->state != LAPDm_STATE_TIMER_RECOV) {
+ /* 5.4.2.2: Inidcate error on supervisory reponse F=1 */
+ LOGP(DLLAPDM, LOGL_NOTICE, "S frame response with F=1 error\n");
+ rsl_rll_error(RLL_CAUSE_UNSOL_SPRV_RESP, mctx);
+ }
+
+ switch (dl->state) {
+ case LAPDm_STATE_IDLE:
+ /* if P=1, respond DM with F=1 (5.2.2) */
+ /* 5.4.5 all other frame types shall be discarded */
+ if (LAPDm_CTRL_PF_BIT(mctx->ctrl))
+ lapdm_send_dm(mctx); /* F=P */
+ /* fall though */
+ case LAPDm_STATE_SABM_SENT:
+ case LAPDm_STATE_DISC_SENT:
+ LOGP(DLLAPDM, LOGL_NOTICE, "S frame ignored in this state\n");
+ msgb_free(msg);
+ return 0;
+ }
+ switch (LAPDm_CTRL_S_BITS(mctx->ctrl)) {
+ case LAPDm_S_RR:
+ LOGP(DLLAPDM, LOGL_INFO, "RR received\n");
+ /* 5.5.3.1: Acknowlege all tx frames up the the N(R)-1 */
+ lapdm_acknowledge(mctx);
+
+ /* 5.5.3.2 */
+ if (LAPDm_ADDR_CR(mctx->addr) == le->cr.rem2loc.cmd
+ && LAPDm_CTRL_PF_BIT(mctx->ctrl)) {
+ if (!dl->own_busy && !dl->seq_err_cond) {
+ LOGP(DLLAPDM, LOGL_NOTICE, "RR frame command "
+ "with polling bit set and we are not "
+ "busy, so we reply with RR frame\n");
+ lapdm_send_rr(mctx, 1);
+ /* NOTE: In case of sequence error condition,
+ * the REJ frame has been transmitted when
+ * entering the condition, so it has not be
+ * done here
+ */
+ } else if (dl->own_busy) {
+ LOGP(DLLAPDM, LOGL_NOTICE, "RR frame command "
+ "with polling bit set and we are busy, "
+ "so we reply with RR frame\n");
+ lapdm_send_rnr(mctx, 1);
+ }
+ } else if (LAPDm_ADDR_CR(mctx->addr) == le->cr.rem2loc.resp
+ && LAPDm_CTRL_PF_BIT(mctx->ctrl)
+ && dl->state == LAPDm_STATE_TIMER_RECOV) {
+ LOGP(DLLAPDM, LOGL_INFO, "RR response with F==1, "
+ "and we are in timer recovery state, so "
+ "we leave that state\n");
+ /* V(S) to the N(R) in the RR frame */
+ dl->V_send = LAPDm_CTRL_Nr(mctx->ctrl);
+ /* reset Timer T200 */
+ osmo_timer_del(&dl->t200);
+ /* 5.5.7 Clear timer recovery condition */
+ lapdm_dl_newstate(dl, LAPDm_STATE_MF_EST);
+ }
+ /* Send message, if possible due to acknowledged data */
+ rslms_send_i(mctx, __LINE__);
+
+ break;
+ case LAPDm_S_RNR:
+ LOGP(DLLAPDM, LOGL_INFO, "RNR received\n");
+ /* 5.5.3.1: Acknowlege all tx frames up the the N(R)-1 */
+ lapdm_acknowledge(mctx);
+
+ /* 5.5.5 */
+ /* Set peer receiver busy condition */
+ dl->peer_busy = 1;
+
+ if (LAPDm_CTRL_PF_BIT(mctx->ctrl)) {
+ if (LAPDm_ADDR_CR(mctx->addr) == le->cr.rem2loc.cmd) {
+ if (!dl->own_busy) {
+ LOGP(DLLAPDM, LOGL_INFO, "RNR poll "
+ "command and we are not busy, "
+ "so we reply with RR final "
+ "response\n");
+ /* Send RR with F=1 */
+ lapdm_send_rr(mctx, 1);
+ } else {
+ LOGP(DLLAPDM, LOGL_INFO, "RNR poll "
+ "command and we are busy, so "
+ "we reply with RNR final "
+ "response\n");
+ /* Send RNR with F=1 */
+ lapdm_send_rnr(mctx, 1);
+ }
+ } else if (dl->state == LAPDm_STATE_TIMER_RECOV) {
+ LOGP(DLLAPDM, LOGL_INFO, "RNR poll response "
+ "and we in timer recovery state, so "
+ "we leave that state\n");
+ /* 5.5.7 Clear timer recovery condition */
+ lapdm_dl_newstate(dl, LAPDm_STATE_MF_EST);
+ /* V(S) to the N(R) in the RNR frame */
+ dl->V_send = LAPDm_CTRL_Nr(mctx->ctrl);
+ }
+ } else
+ LOGP(DLLAPDM, LOGL_INFO, "RNR not polling/final state "
+ "received\n");
+
+ /* Send message, if possible due to acknowledged data */
+ rslms_send_i(mctx, __LINE__);
+
+ break;
+ case LAPDm_S_REJ:
+ LOGP(DLLAPDM, LOGL_INFO, "REJ received\n");
+ /* 5.5.3.1: Acknowlege all tx frames up the the N(R)-1 */
+ lapdm_acknowledge(mctx);
+
+ /* 5.5.4.1 */
+ if (dl->state != LAPDm_STATE_TIMER_RECOV) {
+ /* Clear an existing peer receiver busy condition */
+ dl->peer_busy = 0;
+ /* V(S) and V(A) to the N(R) in the REJ frame */
+ dl->V_send = dl->V_ack = LAPDm_CTRL_Nr(mctx->ctrl);
+ /* reset Timer T200 */
+ osmo_timer_del(&dl->t200);
+ /* 5.5.3.2 */
+ if (LAPDm_ADDR_CR(mctx->addr) == le->cr.rem2loc.cmd
+ && LAPDm_CTRL_PF_BIT(mctx->ctrl)) {
+ if (!dl->own_busy && !dl->seq_err_cond) {
+ LOGP(DLLAPDM, LOGL_INFO, "REJ poll "
+ "command not in timer recovery "
+ "state and not in own busy "
+ "condition received, so we "
+ "respond with RR final "
+ "response\n");
+ lapdm_send_rr(mctx, 1);
+ /* NOTE: In case of sequence error
+ * condition, the REJ frame has been
+ * transmitted when entering the
+ * condition, so it has not be done
+ * here
+ */
+ } else if (dl->own_busy) {
+ LOGP(DLLAPDM, LOGL_INFO, "REJ poll "
+ "command not in timer recovery "
+ "state and in own busy "
+ "condition received, so we "
+ "respond with RNR final "
+ "response\n");
+ lapdm_send_rnr(mctx, 1);
+ }
+ } else
+ LOGP(DLLAPDM, LOGL_INFO, "REJ response or not "
+ "polling command not in timer recovery "
+ "state received\n");
+ /* send MDL ERROR INIDCATION to L3 */
+ if (LAPDm_ADDR_CR(mctx->addr) == le->cr.rem2loc.resp
+ && LAPDm_CTRL_PF_BIT(mctx->ctrl)) {
+ rsl_rll_error(RLL_CAUSE_UNSOL_SPRV_RESP, mctx);
+ }
+
+ } else if (LAPDm_ADDR_CR(mctx->addr) == le->cr.rem2loc.resp
+ && LAPDm_CTRL_PF_BIT(mctx->ctrl)) {
+ LOGP(DLLAPDM, LOGL_INFO, "REJ poll response in timer "
+ "recovery state received\n");
+ /* Clear an existing peer receiver busy condition */
+ dl->peer_busy = 0;
+ /* 5.5.7 Clear timer recovery condition */
+ lapdm_dl_newstate(dl, LAPDm_STATE_MF_EST);
+ /* V(S) and V(A) to the N(R) in the REJ frame */
+ dl->V_send = dl->V_ack = LAPDm_CTRL_Nr(mctx->ctrl);
+ /* reset Timer T200 */
+ osmo_timer_del(&dl->t200);
+ } else {
+ /* Clear an existing peer receiver busy condition */
+ dl->peer_busy = 0;
+ /* V(S) and V(A) to the N(R) in the REJ frame */
+ dl->V_send = dl->V_ack = LAPDm_CTRL_Nr(mctx->ctrl);
+ /* 5.5.3.2 */
+ if (LAPDm_ADDR_CR(mctx->addr) == le->cr.rem2loc.cmd
+ && LAPDm_CTRL_PF_BIT(mctx->ctrl)) {
+ if (!dl->own_busy && !dl->seq_err_cond) {
+ LOGP(DLLAPDM, LOGL_INFO, "REJ poll "
+ "command in timer recovery "
+ "state and not in own busy "
+ "condition received, so we "
+ "respond with RR final "
+ "response\n");
+ lapdm_send_rr(mctx, 1);
+ /* NOTE: In case of sequence error
+ * condition, the REJ frame has been
+ * transmitted when entering the
+ * condition, so it has not be done
+ * here
+ */
+ } else if (dl->own_busy) {
+ LOGP(DLLAPDM, LOGL_INFO, "REJ poll "
+ "command in timer recovery "
+ "state and in own busy "
+ "condition received, so we "
+ "respond with RNR final "
+ "response\n");
+ lapdm_send_rnr(mctx, 1);
+ }
+ } else
+ LOGP(DLLAPDM, LOGL_INFO, "REJ response or not "
+ "polling command in timer recovery "
+ "state received\n");
+ }
+
+ /* FIXME: 5.5.4.2 2) */
+
+ /* Send message, if possible due to acknowledged data */
+ rslms_send_i(mctx, __LINE__);
+
+ break;
+ default:
+ /* G.3.1 */
+ LOGP(DLLAPDM, LOGL_NOTICE, "Supervisory frame not allowed.\n");
+ msgb_free(msg);
+ rsl_rll_error(RLL_CAUSE_FRM_UNIMPL, mctx);
+ return -EINVAL;
+ }
+ msgb_free(msg);
+ return 0;
+}
+
+/* Receive a LAPDm I (Information) message from L1 */
+static int lapdm_rx_i(struct msgb *msg, struct lapdm_msg_ctx *mctx)
+{
+ struct lapdm_datalink *dl = mctx->dl;
+ struct lapdm_entity *le = dl->entity;
+ //uint8_t nr = LAPDm_CTRL_Nr(mctx->ctrl);
+ uint8_t ns = LAPDm_CTRL_I_Ns(mctx->ctrl);
+ uint8_t length;
+ int rc;
+
+ LOGP(DLLAPDM, LOGL_NOTICE, "I received\n");
+
+ /* G.2.2 Wrong value of the C/R bit */
+ if (LAPDm_ADDR_CR(mctx->addr) == le->cr.rem2loc.resp) {
+ LOGP(DLLAPDM, LOGL_NOTICE, "I frame response not allowed\n");
+ msgb_free(msg);
+ rsl_rll_error(RLL_CAUSE_FRM_UNIMPL, mctx);
+ return -EINVAL;
+ }
+
+ length = msg->l2h[2] >> 2;
+ if (length == 0 || length + 3 > mctx->n201) {
+ /* G.4.2 If the length indicator of an I frame is set
+ * to a numerical value L>N201 or L=0, an MDL-ERROR-INDICATION
+ * primitive with cause "I frame with incorrect length"
+ * is sent to the mobile management entity. */
+ LOGP(DLLAPDM, LOGL_NOTICE, "I frame length not allowed\n");
+ msgb_free(msg);
+ rsl_rll_error(RLL_CAUSE_IFRM_INC_LEN, mctx);
+ return -EIO;
+ }
+
+ /* G.4.2 If the numerical value of L is L<N201 and the M
+ * bit is set to "1", then an MDL-ERROR-INDICATION primitive with
+ * cause "I frame with incorrect use of M bit" is sent to the
+ * mobile management entity. */
+ if ((msg->l2h[2] & LAPDm_MORE) && length + 3 < mctx->n201) {
+ LOGP(DLLAPDM, LOGL_NOTICE, "I frame with M bit too short\n");
+ msgb_free(msg);
+ rsl_rll_error(RLL_CAUSE_IFRM_INC_MBITS, mctx);
+ return -EIO;
+ }
+
+ switch (dl->state) {
+ case LAPDm_STATE_IDLE:
+ /* if P=1, respond DM with F=1 (5.2.2) */
+ /* 5.4.5 all other frame types shall be discarded */
+ if (LAPDm_CTRL_PF_BIT(mctx->ctrl))
+ lapdm_send_dm(mctx); /* F=P */
+ /* fall though */
+ case LAPDm_STATE_SABM_SENT:
+ case LAPDm_STATE_DISC_SENT:
+ LOGP(DLLAPDM, LOGL_NOTICE, "I frame ignored in this state\n");
+ msgb_free(msg);
+ return 0;
+ }
+
+ /* 5.7.1: N(s) sequence error */
+ if (ns != dl->V_recv) {
+ LOGP(DLLAPDM, LOGL_NOTICE, "N(S) sequence error: N(S)=%u, "
+ "V(R)=%u\n", ns, dl->V_recv);
+ /* discard data */
+ msgb_free(msg);
+ if (!dl->seq_err_cond) {
+ /* FIXME: help me understand what exactly todo here
+ dl->seq_err_cond = 1;
+ */
+ lapdm_send_rej(mctx, LAPDm_CTRL_PF_BIT(mctx->ctrl));
+ } else {
+ }
+ return -EIO;
+ }
+ dl->seq_err_cond = 0;
+
+ /* Increment receiver state */
+ dl->V_recv = inc_mod8(dl->V_recv);
+ LOGP(DLLAPDM, LOGL_NOTICE, "incrementing V(R) to %u\n", dl->V_recv);
+
+ /* 5.5.3.1: Acknowlege all transmitted frames up the the N(R)-1 */
+ lapdm_acknowledge(mctx); /* V(A) is also set here */
+
+ /* Only if we are not in own receiver busy condition */
+ if (!dl->own_busy) {
+ /* if the frame carries a complete segment */
+ if (!(msg->l2h[2] & LAPDm_MORE)
+ && !dl->rcv_buffer) {
+ LOGP(DLLAPDM, LOGL_INFO, "message in single I frame\n");
+ /* send a DATA INDICATION to L3 */
+ msg->l3h = msg->l2h + 3;
+ msgb_pull_l2h(msg);
+ msg->len = length;
+ msg->tail = msg->data + length;
+ rc = send_rslms_rll_l3(RSL_MT_DATA_IND, mctx, msg);
+ } else {
+ /* create rcv_buffer */
+ if (!dl->rcv_buffer) {
+ LOGP(DLLAPDM, LOGL_INFO, "message in multiple I "
+ "frames (first message)\n");
+ dl->rcv_buffer = msgb_alloc_headroom(200+56, 56,
+ "LAPDm RX");
+ dl->rcv_buffer->l3h = dl->rcv_buffer->data;
+ }
+ /* concat. rcv_buffer */
+ if (msgb_l3len(dl->rcv_buffer) + length > 200) {
+ LOGP(DLLAPDM, LOGL_NOTICE, "Received frame "
+ "overflow!\n");
+ } else {
+ memcpy(msgb_put(dl->rcv_buffer, length),
+ msg->l2h + 3, length);
+ }
+ /* if the last segment was received */
+ if (!(msg->l2h[2] & LAPDm_MORE)) {
+ LOGP(DLLAPDM, LOGL_INFO, "message in multiple I "
+ "frames (last message)\n");
+ rc = send_rslms_rll_l3(RSL_MT_DATA_IND, mctx,
+ dl->rcv_buffer);
+ dl->rcv_buffer = NULL;
+ } else
+ LOGP(DLLAPDM, LOGL_INFO, "message in multiple I "
+ "frames (next message)\n");
+ msgb_free(msg);
+
+ }
+ } else
+ LOGP(DLLAPDM, LOGL_INFO, "I frame ignored during own receiver "
+ "busy condition\n");
+
+ /* Check for P bit */
+ if (LAPDm_CTRL_PF_BIT(mctx->ctrl)) {
+ /* 5.5.2.1 */
+ /* check if we are not in own receiver busy */
+ if (!dl->own_busy) {
+ LOGP(DLLAPDM, LOGL_INFO, "we are not busy, send RR\n");
+ /* Send RR with F=1 */
+ rc = lapdm_send_rr(mctx, 1);
+ } else {
+ LOGP(DLLAPDM, LOGL_INFO, "we are busy, send RNR\n");
+ /* Send RNR with F=1 */
+ rc = lapdm_send_rnr(mctx, 1);
+ }
+ } else {
+ /* 5.5.2.2 */
+ /* check if we are not in own receiver busy */
+ if (!dl->own_busy) {
+ /* NOTE: V(R) is already set above */
+ rc = rslms_send_i(mctx, __LINE__);
+ if (rc) {
+ LOGP(DLLAPDM, LOGL_INFO, "we are not busy and "
+ "have no pending data, send RR\n");
+ /* Send RR with F=0 */
+ return lapdm_send_rr(mctx, 0);
+ }
+ /* all I or one RR is sent, we are done */
+ return 0;
+ } else {
+ LOGP(DLLAPDM, LOGL_INFO, "we are busy, send RNR\n");
+ /* Send RNR with F=0 */
+ rc = lapdm_send_rnr(mctx, 0);
+ }
+ }
+
+ /* Send message, if possible due to acknowledged data */
+ rslms_send_i(mctx, __LINE__);
+
+ return rc;
+}
+
+/* Receive a LAPDm message from L1 */
+static int lapdm_ph_data_ind(struct msgb *msg, struct lapdm_msg_ctx *mctx)
+{
+ int rc;
+
+ /* G.2.3 EA bit set to "0" is not allowed in GSM */
+ if (!LAPDm_ADDR_EA(mctx->addr)) {
+ LOGP(DLLAPDM, LOGL_NOTICE, "EA bit 0 is not allowed in GSM\n");
+ msgb_free(msg);
+ rsl_rll_error(RLL_CAUSE_FRM_UNIMPL, mctx);
+ return -EINVAL;
+ }
+
+ if (LAPDm_CTRL_is_U(mctx->ctrl))
+ rc = lapdm_rx_u(msg, mctx);
+ else if (LAPDm_CTRL_is_S(mctx->ctrl))
+ rc = lapdm_rx_s(msg, mctx);
+ else if (LAPDm_CTRL_is_I(mctx->ctrl))
+ rc = lapdm_rx_i(msg, mctx);
+ else {
+ LOGP(DLLAPDM, LOGL_NOTICE, "unknown LAPDm format\n");
+ msgb_free(msg);
+ rc = -EINVAL;
+ }
+ return rc;
+}
+
+/* input into layer2 (from layer 1) */
+static int l2_ph_data_ind(struct msgb *msg, struct lapdm_entity *le, uint8_t chan_nr, uint8_t link_id)
+{
+ uint8_t cbits = chan_nr >> 3;
+ uint8_t sapi = link_id & 7;
+ struct lapdm_msg_ctx mctx;
+ int rc = 0;
+
+ /* when we reach here, we have a msgb with l2h pointing to the raw
+ * 23byte mac block. The l1h has already been purged. */
+
+ mctx.dl = datalink_for_sapi(le, sapi);
+ mctx.chan_nr = chan_nr;
+ mctx.link_id = link_id;
+ mctx.addr = mctx.ctrl = 0;
+
+ /* G.2.1 No action schall be taken on frames containing an unallocated
+ * SAPI.
+ */
+ if (!mctx.dl) {
+ LOGP(DLLAPDM, LOGL_NOTICE, "Received frame for unsupported "
+ "SAPI %d!\n", sapi);
+ return -EINVAL;
+ msgb_free(msg);
+ return -EIO;
+ }
+
+ /* check for L1 chan_nr/link_id and determine LAPDm hdr format */
+ if (cbits == 0x10 || cbits == 0x12) {
+ /* Format Bbis is used on BCCH and CCCH(PCH, NCH and AGCH) */
+ mctx.lapdm_fmt = LAPDm_FMT_Bbis;
+ mctx.n201 = N201_Bbis;
+ } else {
+ if (mctx.link_id & 0x40) {
+ /* It was received from network on SACCH, thus
+ * lapdm_fmt must be B4 */
+ mctx.lapdm_fmt = LAPDm_FMT_B4;
+ mctx.n201 = N201_B4;
+ LOGP(DLLAPDM, LOGL_INFO, "fmt=B4\n");
+ /* SACCH frames have a two-byte L1 header that
+ * OsmocomBB L1 doesn't strip */
+ mctx.tx_power_ind = msg->l2h[0] & 0x1f;
+ mctx.ta_ind = msg->l2h[1];
+ msgb_pull(msg, 2);
+ msg->l2h += 2;
+ } else {
+ mctx.lapdm_fmt = LAPDm_FMT_B;
+ LOGP(DLLAPDM, LOGL_INFO, "fmt=B\n");
+ mctx.n201 = 23; // FIXME: select correct size by chan.
+ }
+ }
+
+ switch (mctx.lapdm_fmt) {
+ case LAPDm_FMT_A:
+ case LAPDm_FMT_B:
+ case LAPDm_FMT_B4:
+ mctx.addr = msg->l2h[0];
+ if (!(mctx.addr & 0x01)) {
+ LOGP(DLLAPDM, LOGL_ERROR, "we don't support "
+ "multibyte addresses (discarding)\n");
+ msgb_free(msg);
+ return -EINVAL;
+ }
+ mctx.ctrl = msg->l2h[1];
+ /* obtain SAPI from address field */
+ mctx.link_id |= LAPDm_ADDR_SAPI(mctx.addr);
+ rc = lapdm_ph_data_ind(msg, &mctx);
+ break;
+ case LAPDm_FMT_Bter:
+ /* FIXME */
+ msgb_free(msg);
+ break;
+ case LAPDm_FMT_Bbis:
+ /* directly pass up to layer3 */
+ LOGP(DLLAPDM, LOGL_INFO, "fmt=Bbis UI\n");
+ msg->l3h = msg->l2h;
+ msgb_pull_l2h(msg);
+ rc = send_rslms_rll_l3(RSL_MT_UNIT_DATA_IND, &mctx, msg);
+ break;
+ default:
+ msgb_free(msg);
+ }
+
+ return rc;
+}
+
+/* input into layer2 (from layer 1) */
+static int l2_ph_rach_ind(struct lapdm_entity *le, uint8_t ra, uint32_t fn, uint8_t acc_delay)
+{
+ struct abis_rsl_cchan_hdr *ch;
+ struct gsm48_req_ref req_ref;
+ struct gsm_time gt;
+ struct msgb *msg = msgb_alloc_headroom(512, 64, "RSL CHAN RQD");
+
+ msg->l2h = msgb_push(msg, sizeof(*ch));
+ ch = (struct abis_rsl_cchan_hdr *)msg->l2h;
+ rsl_init_cchan_hdr(ch, RSL_MT_CHAN_RQD);
+ ch->chan_nr = RSL_CHAN_RACH;
+
+ /* generate a RSL CHANNEL REQUIRED message */
+ gsm_fn2gsmtime(>, fn);
+ req_ref.ra = ra;
+ req_ref.t1 = gt.t1; /* FIXME: modulo? */
+ req_ref.t2 = gt.t2;
+ req_ref.t3_low = gt.t3 & 7;
+ req_ref.t3_high = gt.t3 >> 3;
+
+ msgb_tv_fixed_put(msg, RSL_IE_REQ_REFERENCE, 3, (uint8_t *) &req_ref);
+ msgb_tv_put(msg, RSL_IE_ACCESS_DELAY, acc_delay);
+
+ return rslms_sendmsg(msg, le);
+}
+
+static int l2_ph_chan_conf(struct msgb *msg, struct lapdm_entity *le, uint32_t frame_nr);
+
+int lapdm_phsap_up(struct osmo_prim_hdr *oph, struct lapdm_entity *le)
+{
+ struct osmo_phsap_prim *pp = (struct osmo_phsap_prim *) oph;
+ int rc = 0;
+
+ if (oph->sap != SAP_GSM_PH) {
+ LOGP(DLLAPDM, LOGL_ERROR, "primitive for unknown SAP %u\n",
+ oph->sap);
+ return -ENODEV;
+ }
+
+ switch (oph->primitive) {
+ case PRIM_PH_DATA:
+ if (oph->operation != PRIM_OP_INDICATION) {
+ LOGP(DLLAPDM, LOGL_ERROR, "PH_DATA is not INDICATION %u\n",
+ oph->operation);
+ return -ENODEV;
+ }
+ rc = l2_ph_data_ind(oph->msg, le, pp->u.data.chan_nr,
+ pp->u.data.link_id);
+ break;
+ case PRIM_PH_RTS:
+ if (oph->operation != PRIM_OP_INDICATION) {
+ LOGP(DLLAPDM, LOGL_ERROR, "PH_RTS is not INDICATION %u\n",
+ oph->operation);
+ return -ENODEV;
+ }
+ rc = l2_ph_data_conf(oph->msg, le);
+ break;
+ case PRIM_PH_RACH:
+ switch (oph->operation) {
+ case PRIM_OP_INDICATION:
+ rc = l2_ph_rach_ind(le, pp->u.rach_ind.ra, pp->u.rach_ind.fn,
+ pp->u.rach_ind.acc_delay);
+ break;
+ case PRIM_OP_CONFIRM:
+ rc = l2_ph_chan_conf(oph->msg, le, pp->u.rach_ind.fn);
+ break;
+ default:
+ return -EIO;
+ }
+ break;
+ }
+
+ return rc;
+}
+
+
+/* L3 -> L2 / RSLMS -> LAPDm */
+
+/* L3 requests establishment of data link */
+static int rslms_rx_rll_est_req(struct msgb *msg, struct lapdm_datalink *dl)
+{
+ struct lapdm_entity *le = dl->entity;
+ struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
+ uint8_t chan_nr = rllh->chan_nr;
+ uint8_t link_id = rllh->link_id;
+ uint8_t sapi = rllh->link_id & 7;
+ struct tlv_parsed tv;
+ uint8_t length;
+ uint8_t n201 = 23; //FIXME
+
+ /* Set chan_nr and link_id for established connection */
+ memset(&dl->mctx, 0, sizeof(dl->mctx));
+ dl->mctx.dl = dl;
+ dl->mctx.n201 = n201;
+ dl->mctx.chan_nr = chan_nr;
+ dl->mctx.link_id = link_id;
+
+ rsl_tlv_parse(&tv, rllh->data, msgb_l2len(msg)-sizeof(*rllh));
+ if (TLVP_PRESENT(&tv, RSL_IE_L3_INFO)) {
+ msg->l3h = TLVP_VAL(&tv, RSL_IE_L3_INFO);
+ /* contention resolution establishment procedure */
+ if (sapi != 0) {
+ /* According to clause 6, the contention resolution
+ * procedure is only permitted with SAPI value 0 */
+ LOGP(DLLAPDM, LOGL_ERROR, "SAPI != 0 but contention"
+ "resolution (discarding)\n");
+ msgb_free(msg);
+ return send_rll_simple(RSL_MT_REL_IND, &dl->mctx);
+ }
+ /* transmit a SABM command with the P bit set to "1". The SABM
+ * command shall contain the layer 3 message unit */
+ length = TLVP_LEN(&tv, RSL_IE_L3_INFO);
+ LOGP(DLLAPDM, LOGL_INFO, "perform establishment with content "
+ "(SABM)\n");
+ } else {
+ /* normal establishment procedure */
+ length = 0;
+ LOGP(DLLAPDM, LOGL_INFO, "perform normal establishm. (SABM)\n");
+ }
+
+ /* check if the layer3 message length exceeds N201 */
+ if (length + 3 > 21) { /* FIXME: do we know the channel N201? */
+ LOGP(DLLAPDM, LOGL_ERROR, "frame too large: %d > N201(%d) "
+ "(discarding)\n", length + 3, 21);
+ msgb_free(msg);
+ return send_rll_simple(RSL_MT_REL_IND, &dl->mctx);
+ }
+
+ /* Flush send-queue */
+ /* Clear send-buffer */
+ lapdm_dl_flush_send(dl);
+
+ /* Discard partly received L3 message */
+ if (dl->rcv_buffer) {
+ msgb_free(dl->rcv_buffer);
+ dl->rcv_buffer = NULL;
+ }
+
+ /* Remove RLL header from msgb */
+ msgb_pull_l2h(msg);
+
+ /* Push LAPDm header on msgb */
+ msg->l2h = msgb_push(msg, 3);
+ msg->l2h[0] = LAPDm_ADDR(LAPDm_LPD_NORMAL, sapi, le->cr.loc2rem.cmd);
+ msg->l2h[1] = LAPDm_CTRL_U(LAPDm_U_SABM, 1);
+ msg->l2h[2] = LAPDm_LEN(length);
+ /* Transmit-buffer carries exactly one segment */
+ memcpy(dl->tx_hist[0], msg->l2h, 3 + length);
+ dl->tx_length[0] = 3 + length;
+ /* set Vs to 0, because it is used as index when resending SABM */
+ dl->V_send = 0;
+
+ /* Set states */
+ dl->own_busy = dl->peer_busy = 0;
+ dl->retrans_ctr = 0;
+ lapdm_dl_newstate(dl, LAPDm_STATE_SABM_SENT);
+
+ /* Tramsmit and start T200 */
+ osmo_timer_schedule(&dl->t200, T200);
+ return tx_ph_data_enqueue(dl, msg, chan_nr, link_id, n201);
+}
+
+/* L3 requests transfer of unnumbered information */
+static int rslms_rx_rll_udata_req(struct msgb *msg, struct lapdm_datalink *dl)
+{
+ struct lapdm_entity *le = dl->entity;
+ struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
+ uint8_t chan_nr = rllh->chan_nr;
+ uint8_t link_id = rllh->link_id;
+ uint8_t sapi = link_id & 7;
+ struct tlv_parsed tv;
+ int length;
+ uint8_t n201 = 23; //FIXME
+ uint8_t ta = 0, tx_power = 0;
+
+ /* check if the layer3 message length exceeds N201 */
+
+ rsl_tlv_parse(&tv, rllh->data, msgb_l2len(msg)-sizeof(*rllh));
+
+ if (TLVP_PRESENT(&tv, RSL_IE_TIMING_ADVANCE)) {
+ ta = *TLVP_VAL(&tv, RSL_IE_TIMING_ADVANCE);
+ }
+ if (TLVP_PRESENT(&tv, RSL_IE_MS_POWER)) {
+ tx_power = *TLVP_VAL(&tv, RSL_IE_MS_POWER);
+ }
+ if (!TLVP_PRESENT(&tv, RSL_IE_L3_INFO)) {
+ LOGP(DLLAPDM, LOGL_ERROR, "unit data request without message "
+ "error\n");
+ msgb_free(msg);
+ return -EINVAL;
+ }
+ msg->l3h = TLVP_VAL(&tv, RSL_IE_L3_INFO);
+ length = TLVP_LEN(&tv, RSL_IE_L3_INFO);
+ /* check if the layer3 message length exceeds N201 */
+ if (length + 5 > 23) { /* FIXME: do we know the channel N201? */
+ LOGP(DLLAPDM, LOGL_ERROR, "frame too large: %d > N201(%d) "
+ "(discarding)\n", length + 5, 23);
+ msgb_free(msg);
+ return -EIO;
+ }
+
+ LOGP(DLLAPDM, LOGL_INFO, "sending unit data (tx_power=%d, ta=%d)\n",
+ tx_power, ta);
+
+ /* Remove RLL header from msgb */
+ msgb_pull_l2h(msg);
+
+ /* Push L1 + LAPDm header on msgb */
+ msg->l2h = msgb_push(msg, 2 + 3);
+ msg->l2h[0] = tx_power;
+ msg->l2h[1] = ta;
+ msg->l2h[2] = LAPDm_ADDR(LAPDm_LPD_NORMAL, sapi, le->cr.loc2rem.cmd);
+ msg->l2h[3] = LAPDm_CTRL_U(LAPDm_U_UI, 0);
+ msg->l2h[4] = LAPDm_LEN(length);
+ // FIXME: short L2 header support
+
+ /* Tramsmit */
+ return tx_ph_data_enqueue(dl, msg, chan_nr, link_id, n201);
+}
+
+/* L3 requests transfer of acknowledged information */
+static int rslms_rx_rll_data_req(struct msgb *msg, struct lapdm_datalink *dl)
+{
+ struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
+ struct tlv_parsed tv;
+
+ rsl_tlv_parse(&tv, rllh->data, msgb_l2len(msg)-sizeof(*rllh));
+ if (!TLVP_PRESENT(&tv, RSL_IE_L3_INFO)) {
+ LOGP(DLLAPDM, LOGL_ERROR, "data request without message "
+ "error\n");
+ msgb_free(msg);
+ return -EINVAL;
+ }
+ msg->l3h = TLVP_VAL(&tv, RSL_IE_L3_INFO);
+
+ LOGP(DLLAPDM, LOGL_INFO, "writing message to send-queue\n");
+
+ /* Remove the RSL/RLL header */
+ msgb_pull_l2h(msg);
+
+ /* Write data into the send queue */
+ msgb_enqueue(&dl->send_queue, msg);
+
+ /* Send message, if possible */
+ rslms_send_i(&dl->mctx, __LINE__);
+ return 0;
+}
+
+/* Send next I frame from queued/buffered data */
+static int rslms_send_i(struct lapdm_msg_ctx *mctx, int line)
+{
+ struct lapdm_datalink *dl = mctx->dl;
+ struct lapdm_entity *le = dl->entity;
+ uint8_t chan_nr = mctx->chan_nr;
+ uint8_t link_id = mctx->link_id;
+ uint8_t sapi = link_id & 7;
+ int k = k_sapi[sapi];
+ struct msgb *msg;
+ int length, left;
+ int rc = - 1; /* we sent nothing */
+
+ LOGP(DLLAPDM, LOGL_INFO, "%s() called from line %d\n", __func__, line);
+
+ next_frame:
+
+ if (dl->peer_busy) {
+ LOGP(DLLAPDM, LOGL_INFO, "peer busy, not sending\n");
+ return rc;
+ }
+
+ if (dl->state == LAPDm_STATE_TIMER_RECOV) {
+ LOGP(DLLAPDM, LOGL_INFO, "timer recovery, not sending\n");
+ return rc;
+ }
+
+ /* If the send state variable V(S) is equal to V(A) plus k
+ * (where k is the maximum number of outstanding I frames - see
+ * subclause 5.8.4), the data link layer entity shall not transmit any
+ * new I frames, but shall retransmit an I frame as a result
+ * of the error recovery procedures as described in subclauses 5.5.4 and
+ * 5.5.7. */
+ if (dl->V_send == add_mod8(dl->V_ack, k)) {
+ LOGP(DLLAPDM, LOGL_INFO, "k frames outstanding, not sending "
+ "more (k=%u V(S)=%u V(A)=%u)\n", k, dl->V_send,
+ dl->V_ack);
+ return rc;
+ }
+
+ /* if we have no tx_hist yet, we create it */
+ if (!dl->tx_length[dl->V_send]) {
+ /* Get next message into send-buffer, if any */
+ if (!dl->send_buffer) {
+ next_message:
+ dl->send_out = 0;
+ dl->send_buffer = msgb_dequeue(&dl->send_queue);
+ /* No more data to be sent */
+ if (!dl->send_buffer)
+ return rc;
+ LOGP(DLLAPDM, LOGL_INFO, "get message from "
+ "send-queue\n");
+ }
+
+ /* How much is left in the send-buffer? */
+ left = msgb_l3len(dl->send_buffer) - dl->send_out;
+ /* Segment, if data exceeds N201 */
+ length = left;
+ if (length > mctx->n201 - 3)
+ length = mctx->n201 - 3;
+ LOGP(DLLAPDM, LOGL_INFO, "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]);
+ /* If message in send-buffer is completely sent */
+ if (left == 0) {
+ msgb_free(dl->send_buffer);
+ dl->send_buffer = NULL;
+ goto next_message;
+ }
+
+ LOGP(DLLAPDM, LOGL_INFO, "send I frame %sV(S)=%d\n",
+ (left > length) ? "segment " : "", dl->V_send);
+
+ /* Create I frame (segment) and transmit-buffer content */
+ msg = msgb_alloc_headroom(23+10, 10, "LAPDm I");
+ msg->l2h = msgb_put(msg, 3 + length);
+ msg->l2h[0] = LAPDm_ADDR(LAPDm_LPD_NORMAL, sapi, le->cr.loc2rem.cmd);
+ msg->l2h[1] = LAPDm_CTRL_I(dl->V_recv, dl->V_send, 0);
+ msg->l2h[2] = LAPDm_LEN(length);
+ if (left > length)
+ msg->l2h[2] |= LAPDm_MORE;
+ memcpy(msg->l2h + 3, dl->send_buffer->l3h + dl->send_out,
+ length);
+ memcpy(dl->tx_hist[dl->V_send], msg->l2h, 3 + length);
+ dl->tx_length[dl->V_send] = 3 + length;
+ /* Add length to track how much is already in the tx buffer */
+ dl->send_out += length;
+ } else {
+ LOGP(DLLAPDM, LOGL_INFO, "resend I frame from tx buffer "
+ "V(S)=%d\n", dl->V_send);
+
+ /* Create I frame (segment) from tx_hist */
+ length = dl->tx_length[dl->V_send];
+ msg = msgb_alloc_headroom(23+10, 10, "LAPDm I");
+ msg->l2h = msgb_put(msg, length);
+ memcpy(msg->l2h, dl->tx_hist[dl->V_send], length);
+ msg->l2h[1] = LAPDm_CTRL_I(dl->V_recv, dl->V_send, 0);
+ }
+
+ /* The value of the send state variable V(S) shall be incremented by 1
+ * at the end of the transmission of the I frame */
+ dl->V_send = inc_mod8(dl->V_send);
+
+ /* If timer T200 is not running at the time right before transmitting a
+ * frame, when the PH-READY-TO-SEND primitive is received from the
+ * physical layer., it shall be set. */
+ if (!osmo_timer_pending(&dl->t200))
+ osmo_timer_schedule(&dl->t200, T200);
+
+ tx_ph_data_enqueue(dl, msg, chan_nr, link_id, mctx->n201);
+
+ rc = 0; /* we sent something */
+ goto next_frame;
+}
+
+/* L3 requests suspension of data link */
+static int rslms_rx_rll_susp_req(struct msgb *msg, struct lapdm_datalink *dl)
+{
+ struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
+ uint8_t sapi = rllh->link_id & 7;
+
+ if (sapi != 0) {
+ LOGP(DLLAPDM, LOGL_ERROR, "SAPI != 0 while suspending\n");
+ msgb_free(msg);
+ return -EINVAL;
+ }
+
+ LOGP(DLLAPDM, LOGL_INFO, "perform suspension\n");
+
+ /* put back the send-buffer to the send-queue (first position) */
+ if (dl->send_buffer) {
+ LOGP(DLLAPDM, LOGL_INFO, "put frame in sendbuffer back to "
+ "queue\n");
+ llist_add(&dl->send_buffer->list, &dl->send_queue);
+ dl->send_buffer = NULL;
+ } else
+ LOGP(DLLAPDM, LOGL_INFO, "no frame in sendbuffer\n");
+
+ /* Clear transmit buffer, but keep send buffer */
+ lapdm_dl_flush_tx(dl);
+
+ msgb_free(msg);
+
+ return send_rll_simple(RSL_MT_SUSP_CONF, &dl->mctx);
+}
+
+/* L3 requests resume of data link */
+static int rslms_rx_rll_res_req(struct msgb *msg, struct lapdm_datalink *dl)
+{
+ struct lapdm_entity *le = dl->entity;
+ struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
+ uint8_t chan_nr = rllh->chan_nr;
+ uint8_t link_id = rllh->link_id;
+ uint8_t sapi = rllh->link_id & 7;
+ struct tlv_parsed tv;
+ uint8_t length;
+ uint8_t n201 = 23; //FIXME
+
+ /* Set chan_nr and link_id for established connection */
+ memset(&dl->mctx, 0, sizeof(dl->mctx));
+ dl->mctx.dl = dl;
+ dl->mctx.n201 = n201;
+ dl->mctx.chan_nr = chan_nr;
+ dl->mctx.link_id = link_id;
+
+ rsl_tlv_parse(&tv, rllh->data, msgb_l2len(msg)-sizeof(*rllh));
+ if (!TLVP_PRESENT(&tv, RSL_IE_L3_INFO)) {
+ LOGP(DLLAPDM, LOGL_ERROR, "resume without message error\n");
+ msgb_free(msg);
+ return send_rll_simple(RSL_MT_REL_IND, &dl->mctx);
+ }
+ length = TLVP_LEN(&tv, RSL_IE_L3_INFO);
+
+ LOGP(DLLAPDM, LOGL_INFO, "perform re-establishment (SABM) length=%d\n",
+ length);
+
+ /* Replace message in the send-buffer (reconnect) */
+ if (dl->send_buffer)
+ msgb_free(dl->send_buffer);
+ dl->send_out = 0;
+ if (length) {
+ /* Remove the RSL/RLL header */
+ msgb_pull_l2h(msg);
+ /* Write data into the send buffer, to be sent first */
+ dl->send_buffer = msg;
+ }
+
+ /* Discard partly received L3 message */
+ if (dl->rcv_buffer) {
+ msgb_free(dl->rcv_buffer);
+ dl->rcv_buffer = NULL;
+ }
+
+ /* Create new msgb (old one is now free) */
+ msg = msgb_alloc_headroom(23+10, 10, "LAPDm SABM");
+ msg->l2h = msgb_put(msg, 3);
+ msg->l2h[0] = LAPDm_ADDR(LAPDm_LPD_NORMAL, sapi, le->cr.loc2rem.cmd);
+ msg->l2h[1] = LAPDm_CTRL_U(LAPDm_U_SABM, 1);
+ msg->l2h[2] = LAPDm_LEN(0);
+ /* Transmit-buffer carries exactly one segment */
+ memcpy(dl->tx_hist[0], msg->l2h, 3);
+ dl->tx_length[0] = 3;
+ /* set Vs to 0, because it is used as index when resending SABM */
+ dl->V_send = 0;
+
+ /* Set states */
+ dl->own_busy = dl->peer_busy = 0;
+ dl->retrans_ctr = 0;
+ lapdm_dl_newstate(dl, LAPDm_STATE_SABM_SENT);
+
+ /* Tramsmit and start T200 */
+ osmo_timer_schedule(&dl->t200, T200);
+ return tx_ph_data_enqueue(dl, msg, chan_nr, link_id, n201);
+}
+
+/* L3 requests release of data link */
+static int rslms_rx_rll_rel_req(struct msgb *msg, struct lapdm_datalink *dl)
+{
+ struct lapdm_entity *le = dl->entity;
+ struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
+ uint8_t chan_nr = rllh->chan_nr;
+ uint8_t link_id = rllh->link_id;
+ uint8_t sapi = rllh->link_id & 7;
+ uint8_t mode = 0;
+
+ /* get release mode */
+ if (rllh->data[0] == RSL_IE_RELEASE_MODE)
+ mode = rllh->data[1] & 1;
+
+ /* local release */
+ if (mode) {
+ LOGP(DLLAPDM, LOGL_INFO, "perform local release\n");
+ msgb_free(msg);
+ /* reset Timer T200 */
+ osmo_timer_del(&dl->t200);
+ /* enter idle state */
+ lapdm_dl_newstate(dl, LAPDm_STATE_IDLE);
+ /* flush buffers */
+ lapdm_dl_flush_tx(dl);
+ lapdm_dl_flush_send(dl);
+ /* send notification to L3 */
+ return send_rll_simple(RSL_MT_REL_CONF, &dl->mctx);
+ }
+
+ /* in case we are already disconnecting */
+ if (dl->state == LAPDm_STATE_DISC_SENT)
+ return -EBUSY;
+
+ LOGP(DLLAPDM, LOGL_INFO, "perform normal release (DISC)\n");
+
+ /* Pull rllh */
+ msgb_pull(msg, msg->tail - msg->l2h);
+
+ /* Push LAPDm header on msgb */
+ msg->l2h = msgb_push(msg, 3);
+ msg->l2h[0] = LAPDm_ADDR(LAPDm_LPD_NORMAL, sapi, le->cr.loc2rem.cmd);
+ msg->l2h[1] = LAPDm_CTRL_U(LAPDm_U_DISC, 1);
+ msg->l2h[2] = LAPDm_LEN(0);
+ /* Transmit-buffer carries exactly one segment */
+ memcpy(dl->tx_hist[0], msg->l2h, 3);
+ dl->tx_length[0] = 3;
+
+ /* Set states */
+ dl->own_busy = dl->peer_busy = 0;
+ dl->retrans_ctr = 0;
+ lapdm_dl_newstate(dl, LAPDm_STATE_DISC_SENT);
+
+ /* Tramsmit and start T200 */
+ osmo_timer_schedule(&dl->t200, T200);
+ return tx_ph_data_enqueue(dl, msg, chan_nr, link_id, dl->mctx.n201);
+}
+
+/* L3 requests release in idle state */
+static int rslms_rx_rll_rel_req_idle(struct msgb *msg, struct lapdm_datalink *dl)
+{
+ msgb_free(msg);
+
+ /* send notification to L3 */
+ return send_rll_simple(RSL_MT_REL_CONF, &dl->mctx);
+}
+
+/* L3 requests channel in idle state */
+static int rslms_rx_chan_rqd(struct lapdm_channel *lc, struct msgb *msg)
+{
+ struct abis_rsl_cchan_hdr *cch = msgb_l2(msg);
+ void *l1ctx = lc->lapdm_dcch.l1_ctx;
+ struct osmo_phsap_prim pp;
+
+ osmo_prim_init(&pp.oph, SAP_GSM_PH, PRIM_PH_RACH,
+ PRIM_OP_REQUEST, NULL);
+
+ if (msgb_l2len(msg) < sizeof(*cch) + 4 + 2 + 2) {
+ LOGP(DLLAPDM, LOGL_ERROR, "Message too short for CHAN RQD!\n");
+ return -EINVAL;
+ }
+ if (cch->data[0] != RSL_IE_REQ_REFERENCE) {
+ LOGP(DLLAPDM, LOGL_ERROR, "Missing REQ REFERENCE IE\n");
+ return -EINVAL;
+ }
+ pp.u.rach_req.ra = cch->data[1];
+ pp.u.rach_req.offset = ((cch->data[2] & 0x7f) << 8) | cch->data[3];
+ pp.u.rach_req.is_combined_ccch = cch->data[2] >> 7;
+
+ if (cch->data[4] != RSL_IE_ACCESS_DELAY) {
+ LOGP(DLLAPDM, LOGL_ERROR, "Missing ACCESS_DELAY IE\n");
+ return -EINVAL;
+ }
+ /* TA = 0 - delay */
+ pp.u.rach_req.ta = 0 - cch->data[5];
+
+ if (cch->data[6] != RSL_IE_MS_POWER) {
+ LOGP(DLLAPDM, LOGL_ERROR, "Missing MS POWER IE\n");
+ return -EINVAL;
+ }
+ pp.u.rach_req.tx_power = cch->data[7];
+
+ msgb_free(msg);
+
+ return lc->lapdm_dcch.l1_prim_cb(&pp.oph, l1ctx);
+}
+
+/* L1 confirms channel request */
+static int l2_ph_chan_conf(struct msgb *msg, struct lapdm_entity *le, uint32_t frame_nr)
+{
+ struct abis_rsl_cchan_hdr *ch;
+ struct gsm_time tm;
+ struct gsm48_req_ref *ref;
+
+ gsm_fn2gsmtime(&tm, frame_nr);
+
+ msgb_pull_l2h(msg);
+ msg->l2h = msgb_push(msg, sizeof(*ch) + sizeof(*ref));
+ ch = (struct abis_rsl_cchan_hdr *)msg->l2h;
+ rsl_init_cchan_hdr(ch, RSL_MT_CHAN_CONF);
+ ch->chan_nr = RSL_CHAN_RACH;
+ ch->data[0] = RSL_IE_REQ_REFERENCE;
+ ref = (struct gsm48_req_ref *) (ch->data + 1);
+ ref->t1 = tm.t1;
+ ref->t2 = tm.t2;
+ ref->t3_low = tm.t3 & 0x7;
+ ref->t3_high = tm.t3 >> 3;
+
+ return rslms_sendmsg(msg, le);
+}
+
+const char *lapdm_state_names[] = {
+ "LAPDm_STATE_NULL",
+ "LAPDm_STATE_IDLE",
+ "LAPDm_STATE_SABM_SENT",
+ "LAPDm_STATE_MF_EST",
+ "LAPDm_STATE_TIMER_RECOV",
+ "LAPDm_STATE_DISC_SENT",
+};
+
+/* statefull handling for RSLms RLL messages from L3 */
+static struct l2downstate {
+ uint32_t states;
+ int type;
+ int (*rout) (struct msgb *msg, struct lapdm_datalink *dl);
+} l2downstatelist[] = {
+ /* create and send UI command */
+ {ALL_STATES,
+ RSL_MT_UNIT_DATA_REQ, rslms_rx_rll_udata_req},
+
+ /* create and send SABM command */
+ {SBIT(LAPDm_STATE_IDLE),
+ RSL_MT_EST_REQ, rslms_rx_rll_est_req},
+
+ /* create and send I command */
+ {SBIT(LAPDm_STATE_MF_EST) |
+ SBIT(LAPDm_STATE_TIMER_RECOV),
+ RSL_MT_DATA_REQ, rslms_rx_rll_data_req},
+
+ /* suspend datalink */
+ {SBIT(LAPDm_STATE_MF_EST) |
+ SBIT(LAPDm_STATE_TIMER_RECOV),
+ RSL_MT_SUSP_REQ, rslms_rx_rll_susp_req},
+
+ /* create and send SABM command (resume) */
+ {SBIT(LAPDm_STATE_MF_EST) |
+ SBIT(LAPDm_STATE_TIMER_RECOV),
+ RSL_MT_RES_REQ, rslms_rx_rll_res_req},
+
+ /* create and send SABM command (reconnect) */
+ {SBIT(LAPDm_STATE_IDLE) |
+ SBIT(LAPDm_STATE_MF_EST) |
+ SBIT(LAPDm_STATE_TIMER_RECOV),
+ RSL_MT_RECON_REQ, rslms_rx_rll_res_req},
+
+ /* create and send DISC command */
+ {SBIT(LAPDm_STATE_SABM_SENT) |
+ SBIT(LAPDm_STATE_MF_EST) |
+ SBIT(LAPDm_STATE_TIMER_RECOV) |
+ SBIT(LAPDm_STATE_DISC_SENT),
+ RSL_MT_REL_REQ, rslms_rx_rll_rel_req},
+
+ /* release in idle state */
+ {SBIT(LAPDm_STATE_IDLE),
+ RSL_MT_REL_REQ, rslms_rx_rll_rel_req_idle},
+};
+
+#define L2DOWNSLLEN \
+ (sizeof(l2downstatelist) / sizeof(struct l2downstate))
+
+/* incoming RSLms RLL message from L3 */
+static int rslms_rx_rll(struct msgb *msg, struct lapdm_channel *lc)
+{
+ struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
+ int msg_type = rllh->c.msg_type;
+ uint8_t sapi = rllh->link_id & 7;
+ struct lapdm_entity *le;
+ struct lapdm_datalink *dl;
+ int i, supported = 0;
+ int rc = 0;
+
+ if (msgb_l2len(msg) < sizeof(*rllh)) {
+ LOGP(DLLAPDM, LOGL_ERROR, "Message too short for RLL hdr!\n");
+ return -EINVAL;
+ }
+
+ if (rllh->link_id & 0x40)
+ le = &lc->lapdm_acch;
+ else
+ le = &lc->lapdm_dcch;
+
+ /* G.2.1 No action schall be taken on frames containing an unallocated
+ * SAPI.
+ */
+ dl = datalink_for_sapi(le, sapi);
+ if (!dl) {
+ LOGP(DLLAPDM, LOGL_ERROR, "No instance for SAPI %d!\n", sapi);
+ return -EINVAL;
+ }
+
+ LOGP(DLLAPDM, LOGL_INFO, "(%p) RLL Message '%s' received in state %s\n",
+ lc->name, rsl_msg_name(msg_type), lapdm_state_names[dl->state]);
+
+ /* find function for current state and message */
+ for (i = 0; i < L2DOWNSLLEN; i++) {
+ if (msg_type == l2downstatelist[i].type)
+ supported = 1;
+ if ((msg_type == l2downstatelist[i].type)
+ && ((1 << dl->state) & l2downstatelist[i].states))
+ break;
+ }
+ if (!supported) {
+ LOGP(DLLAPDM, LOGL_NOTICE, "Message unsupported.\n");
+ msgb_free(msg);
+ return 0;
+ }
+ if (i == L2DOWNSLLEN) {
+ LOGP(DLLAPDM, LOGL_NOTICE, "Message unhandled at this state.\n");
+ msgb_free(msg);
+ return 0;
+ }
+
+ rc = l2downstatelist[i].rout(msg, dl);
+
+ return rc;
+}
+
+/* incoming RSLms COMMON CHANNEL message from L3 */
+static int rslms_rx_com_chan(struct msgb *msg, struct lapdm_channel *lc)
+{
+ struct abis_rsl_cchan_hdr *cch = msgb_l2(msg);
+ int msg_type = cch->c.msg_type;
+ int rc = 0;
+
+ if (msgb_l2len(msg) < sizeof(*cch)) {
+ LOGP(DLLAPDM, LOGL_ERROR, "Message too short for COM CHAN hdr!\n");
+ return -EINVAL;
+ }
+
+ switch (msg_type) {
+ case RSL_MT_CHAN_RQD:
+ /* create and send RACH request */
+ rc = rslms_rx_chan_rqd(lc, msg);
+ break;
+ default:
+ LOGP(DLLAPDM, LOGL_NOTICE, "Unknown COMMON CHANNEL msg %d!\n",
+ msg_type);
+ msgb_free(msg);
+ return 0;
+ }
+
+ return rc;
+}
+
+/* input into layer2 (from layer 3) */
+int lapdm_rslms_recvmsg(struct msgb *msg, struct lapdm_channel *lc)
+{
+ struct abis_rsl_common_hdr *rslh = msgb_l2(msg);
+ int rc = 0;
+
+ if (msgb_l2len(msg) < sizeof(*rslh)) {
+ LOGP(DLLAPDM, LOGL_ERROR, "Message too short RSL hdr!\n");
+ return -EINVAL;
+ }
+
+ switch (rslh->msg_discr & 0xfe) {
+ case ABIS_RSL_MDISC_RLL:
+ rc = rslms_rx_rll(msg, lc);
+ break;
+ case ABIS_RSL_MDISC_COM_CHAN:
+ rc = rslms_rx_com_chan(msg, lc);
+ break;
+ default:
+ LOGP(DLLAPDM, LOGL_ERROR, "unknown RSLms message "
+ "discriminator 0x%02x", rslh->msg_discr);
+ msgb_free(msg);
+ return -EINVAL;
+ }
+
+ return rc;
+}
+
+int lapdm_entity_set_mode(struct lapdm_entity *le, enum lapdm_mode mode)
+{
+ switch (mode) {
+ case LAPDM_MODE_MS:
+ le->cr.loc2rem.cmd = CR_MS2BS_CMD;
+ le->cr.loc2rem.resp = CR_MS2BS_RESP;
+ le->cr.rem2loc.cmd = CR_BS2MS_CMD;
+ le->cr.rem2loc.resp = CR_BS2MS_RESP;
+ break;
+ case LAPDM_MODE_BTS:
+ le->cr.loc2rem.cmd = CR_BS2MS_CMD;
+ le->cr.loc2rem.resp = CR_BS2MS_RESP;
+ le->cr.rem2loc.cmd = CR_MS2BS_CMD;
+ le->cr.rem2loc.resp = CR_MS2BS_RESP;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ le->mode = mode;
+
+ return 0;
+}
+
+int lapdm_channel_set_mode(struct lapdm_channel *lc, enum lapdm_mode mode)
+{
+ int rc;
+
+ rc = lapdm_entity_set_mode(&lc->lapdm_dcch, mode);
+ if (rc < 0)
+ return rc;
+
+ return lapdm_entity_set_mode(&lc->lapdm_acch, mode);
+}
+
+void lapdm_channel_set_l1(struct lapdm_channel *lc, osmo_prim_cb cb, void *ctx)
+{
+ lc->lapdm_dcch.l1_prim_cb = cb;
+ lc->lapdm_acch.l1_prim_cb = cb;
+ lc->lapdm_dcch.l1_ctx = ctx;
+ lc->lapdm_acch.l1_ctx = ctx;
+}
+
+void lapdm_channel_set_l3(struct lapdm_channel *lc, lapdm_cb_t cb, void *ctx)
+{
+ lc->lapdm_dcch.l3_cb = cb;
+ lc->lapdm_acch.l3_cb = cb;
+ lc->lapdm_dcch.l3_ctx = ctx;
+ lc->lapdm_acch.l3_ctx = ctx;
+}
+
+void lapdm_entity_reset(struct lapdm_entity *le)
+{
+ struct lapdm_datalink *dl;
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(le->datalink); i++) {
+ dl = &le->datalink[i];
+ if (dl->state == LAPDm_STATE_IDLE)
+ continue;
+ LOGP(DLLAPDM, LOGL_INFO, "Resetting LAPDm instance\n");
+ /* reset Timer T200 */
+ osmo_timer_del(&dl->t200);
+ /* enter idle state */
+ dl->state = LAPDm_STATE_IDLE;
+ /* flush buffer */
+ lapdm_dl_flush_tx(dl);
+ lapdm_dl_flush_send(dl);
+ }
+}
+
+void lapdm_channel_reset(struct lapdm_channel *lc)
+{
+ lapdm_entity_reset(&lc->lapdm_dcch);
+ lapdm_entity_reset(&lc->lapdm_acch);
+}
+
+void lapdm_entity_set_flags(struct lapdm_entity *le, unsigned int flags)
+{
+ le->flags = flags;
+}
+
+void lapdm_channel_set_flags(struct lapdm_channel *lc, unsigned int flags)
+{
+ lapdm_entity_set_flags(&lc->lapdm_dcch, flags);
+ lapdm_entity_set_flags(&lc->lapdm_acch, flags);
+}
projects / osmocom-bb.git / commitdiff