From 1f0b8c26f78a71b1dd948c464f15d0166e706792 Mon Sep 17 00:00:00 2001 From: Harald Welte Date: Mon, 27 Jun 2011 10:51:37 +0200 Subject: add LAPDm code from osmocom-bb into libosmocore --- src/gsm/Makefile.am | 3 +- src/gsm/lapdm.c | 2510 +++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 2512 insertions(+), 1 deletion(-) create mode 100644 src/gsm/lapdm.c (limited to 'src/gsm') diff --git a/src/gsm/Makefile.am b/src/gsm/Makefile.am index 74893270..88b2d9a7 100644 --- a/src/gsm/Makefile.am +++ b/src/gsm/Makefile.am @@ -9,6 +9,7 @@ lib_LTLIBRARIES = libosmogsm.la libosmogsm_la_SOURCES = a5.c rxlev_stat.c tlv_parser.c comp128.c gsm_utils.c \ rsl.c gsm48.c gsm48_ie.c gsm0808.c sysinfo.c \ - gprs_cipher_core.c gsm0480.c abis_nm.c gsm0502.c + gprs_cipher_core.c gsm0480.c abis_nm.c gsm0502.c \ + lapdm.c libosmogsm_la_LDFLAGS = -version-info $(LIBVERSION) libosmogsm_la_LIBADD = $(top_builddir)/src/libosmocore.la diff --git a/src/gsm/lapdm.c b/src/gsm/lapdm.c new file mode 100644 index 00000000..b804a929 --- /dev/null +++ b/src/gsm/lapdm.c @@ -0,0 +1,2510 @@ +/* GSM LAPDm (TS 04.06) implementation */ + +/* (C) 2010-2011 by Harald Welte + * (C) 2010 by Andreas Eversberg + * + * 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 +#include +#include +#include +#include + +#include +#include +#include +#include + +#include +#include +#include +#include +#include + +#include +#include + +/* 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 Ll2h[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]