diff options
Diffstat (limited to 'src/shared/libosmocore/src/gsm/lapd_core.c')
| -rw-r--r-- | src/shared/libosmocore/src/gsm/lapd_core.c | 2169 |
1 files changed, 0 insertions, 2169 deletions
diff --git a/src/shared/libosmocore/src/gsm/lapd_core.c b/src/shared/libosmocore/src/gsm/lapd_core.c deleted file mode 100644 index 96099edb..00000000 --- a/src/shared/libosmocore/src/gsm/lapd_core.c +++ /dev/null @@ -1,2169 +0,0 @@ -/* LAPD core implementation */ - -/* (C) 2010-2011 by Harald Welte <laforge@gnumonks.org> - * (C) 2010-2011 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. - * - */ - -/*! \addtogroup lapd - * @{ - */ - -/*! \file lapd.c */ - -/*! - * 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. - * - * T203 is optional. It will be stated when entering MF EST state. It will also - * be started when I or S frame is received in that state . It will be - * restarted in the lapd_acknowledge() function, in case outstanding frames - * will not trigger T200. It will be stoped, when T200 is started in MF EST - * state. It will also be stoped when leaving MF EST state. - * - */ - -/* Enable this to test content resolution on network side: - * - The first SABM is received, UA is dropped. - * - The phone repeats SABM, but it's content is wrong, so it is ignored - * - The phone repeats SABM again, content is right, so UA is sent. - */ -//#define TEST_CONTENT_RESOLUTION_NETWORK - -#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/core/talloc.h> -#include <osmocom/gsm/lapd_core.h> - -/* TS 04.06 Table 4 / Section 3.8.1 */ -#define LAPD_U_SABM 0x7 -#define LAPD_U_SABME 0xf -#define LAPD_U_DM 0x3 -#define LAPD_U_UI 0x0 -#define LAPD_U_DISC 0x8 -#define LAPD_U_UA 0xC -#define LAPD_U_FRMR 0x11 - -#define LAPD_S_RR 0x0 -#define LAPD_S_RNR 0x1 -#define LAPD_S_REJ 0x2 - -#define CR_USER2NET_CMD 0 -#define CR_USER2NET_RESP 1 -#define CR_NET2USER_CMD 1 -#define CR_NET2USER_RESP 0 - -#define LAPD_HEADROOM 56 - -#define SBIT(a) (1 << a) -#define ALL_STATES 0xffffffff - -static void lapd_t200_cb(void *data); -static void lapd_t203_cb(void *data); -static int lapd_send_i(struct lapd_msg_ctx *lctx, int line); -static int lapd_est_req(struct osmo_dlsap_prim *dp, struct lapd_msg_ctx *lctx); - -/* UTILITY FUNCTIONS */ - -struct msgb *lapd_msgb_alloc(int length, const char *name) -{ - /* adding space for padding, FIXME: add as an option */ - if (length < 21) - length = 21; - return msgb_alloc_headroom(length + LAPD_HEADROOM, LAPD_HEADROOM, name); -} - -static inline uint8_t do_mod(uint8_t x, uint8_t m) -{ - return x & (m - 1); -} - -static inline uint8_t inc_mod(uint8_t x, uint8_t m) -{ - return (x + 1) & (m - 1); -} - -static inline uint8_t add_mod(uint8_t x, uint8_t y, uint8_t m) -{ - return (x + y) & (m - 1); -} - -static inline uint8_t sub_mod(uint8_t x, uint8_t y, uint8_t m) -{ - return (x - y) & (m - 1); /* handle negative results correctly */ -} - -static void lapd_dl_flush_send(struct lapd_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 lapd_dl_flush_hist(struct lapd_datalink *dl) -{ - unsigned int i; - - for (i = 0; i < dl->range_hist; i++) { - if (dl->tx_hist[i].msg) { - msgb_free(dl->tx_hist[i].msg); - dl->tx_hist[i].msg = NULL; - } - } -} - -static void lapd_dl_flush_tx(struct lapd_datalink *dl) -{ - struct msgb *msg; - - while ((msg = msgb_dequeue(&dl->tx_queue))) - msgb_free(msg); - lapd_dl_flush_hist(dl); -} - -/* Figure B.2/Q.921 */ -const char *lapd_state_names[] = { - "LAPD_STATE_NULL", - "LAPD_STATE_TEI_UNASS", - "LAPD_STATE_ASS_TEI_WAIT", - "LAPD_STATE_EST_TEI_WAIT", - "LAPD_STATE_IDLE", - "LAPD_STATE_SABM_SENT", - "LAPD_STATE_DISC_SENT", - "LAPD_STATE_MF_EST", - "LAPD_STATE_TIMER_RECOV", - -}; - -static void lapd_start_t200(struct lapd_datalink *dl) -{ - if (osmo_timer_pending(&dl->t200)) - return; - LOGP(DLLAPD, LOGL_INFO, "start T200\n"); - osmo_timer_schedule(&dl->t200, dl->t200_sec, dl->t200_usec); -} - -static void lapd_start_t203(struct lapd_datalink *dl) -{ - if (osmo_timer_pending(&dl->t203)) - return; - LOGP(DLLAPD, LOGL_INFO, "start T203\n"); - osmo_timer_schedule(&dl->t203, dl->t203_sec, dl->t203_usec); -} - -static void lapd_stop_t200(struct lapd_datalink *dl) -{ - if (!osmo_timer_pending(&dl->t200)) - return; - LOGP(DLLAPD, LOGL_INFO, "stop T200\n"); - osmo_timer_del(&dl->t200); -} - -static void lapd_stop_t203(struct lapd_datalink *dl) -{ - if (!osmo_timer_pending(&dl->t203)) - return; - LOGP(DLLAPD, LOGL_INFO, "stop T203\n"); - osmo_timer_del(&dl->t203); -} - -static void lapd_dl_newstate(struct lapd_datalink *dl, uint32_t state) -{ - LOGP(DLLAPD, LOGL_INFO, "new state %s -> %s\n", - lapd_state_names[dl->state], lapd_state_names[state]); - - if (state != LAPD_STATE_MF_EST && dl->state == LAPD_STATE_MF_EST) { - /* stop T203 on leaving MF EST state, if running */ - lapd_stop_t203(dl); - /* remove content res. (network side) on leaving MF EST state */ - if (dl->cont_res) { - msgb_free(dl->cont_res); - dl->cont_res = NULL; - } - } - - /* start T203 on entering MF EST state, if enabled */ - if ((dl->t203_sec || dl->t203_usec) - && state == LAPD_STATE_MF_EST && dl->state != LAPD_STATE_MF_EST) - lapd_start_t203(dl); - - dl->state = state; -} - -static void *tall_lapd_ctx = NULL; - -/* init datalink instance and allocate history */ -void lapd_dl_init(struct lapd_datalink *dl, uint8_t k, uint8_t v_range, - int maxf) -{ - int m; - - memset(dl, 0, sizeof(*dl)); - INIT_LLIST_HEAD(&dl->send_queue); - INIT_LLIST_HEAD(&dl->tx_queue); - dl->reestablish = 1; - dl->n200_est_rel = 3; - dl->n200 = 3; - dl->t200_sec = 1; - dl->t200_usec = 0; - dl->t200.data = dl; - dl->t200.cb = &lapd_t200_cb; - dl->t203_sec = 10; - dl->t203_usec = 0; - dl->t203.data = dl; - dl->t203.cb = &lapd_t203_cb; - dl->maxf = maxf; - if (k > v_range - 1) - k = v_range - 1; - dl->k = k; - dl->v_range = v_range; - - /* Calculate modulo for history array: - * - The history range must be at least k+1. - * - The history range must be 2^x, where x is as low as possible. - */ - k++; - for (m = 0x80; m; m >>= 1) { - if ((m & k)) { - if (k > m) - m <<= 1; - dl->range_hist = m; - break; - } - } - - LOGP(DLLAPD, LOGL_INFO, "Init DL layer: sequence range = %d, k = %d, " - "history range = %d\n", dl->v_range, dl->k, dl->range_hist); - - lapd_dl_newstate(dl, LAPD_STATE_IDLE); - - if (!tall_lapd_ctx) - tall_lapd_ctx = talloc_named_const(NULL, 1, "lapd context"); - dl->tx_hist = (struct lapd_history *) talloc_zero_array(tall_lapd_ctx, - struct log_info, dl->range_hist); -} - -/* reset to IDLE state */ -void lapd_dl_reset(struct lapd_datalink *dl) -{ - if (dl->state == LAPD_STATE_IDLE) - return; - LOGP(DLLAPD, LOGL_INFO, "Resetting LAPDm instance\n"); - /* enter idle state (and remove eventual cont_res) */ - lapd_dl_newstate(dl, LAPD_STATE_IDLE); - /* flush buffer */ - lapd_dl_flush_tx(dl); - lapd_dl_flush_send(dl); - /* Discard partly received L3 message */ - if (dl->rcv_buffer) { - msgb_free(dl->rcv_buffer); - dl->rcv_buffer = NULL; - } - /* stop Timers */ - lapd_stop_t200(dl); - lapd_stop_t203(dl); -} - -/* reset and de-allocate history buffer */ -void lapd_dl_exit(struct lapd_datalink *dl) -{ - /* free all ressources except history buffer */ - lapd_dl_reset(dl); - /* free history buffer list */ - talloc_free(dl->tx_hist); -} - -/*! \brief Set the \ref lapdm_mode of a LAPDm entity */ -int lapd_set_mode(struct lapd_datalink *dl, enum lapd_mode mode) -{ - switch (mode) { - case LAPD_MODE_USER: - dl->cr.loc2rem.cmd = CR_USER2NET_CMD; - dl->cr.loc2rem.resp = CR_USER2NET_RESP; - dl->cr.rem2loc.cmd = CR_NET2USER_CMD; - dl->cr.rem2loc.resp = CR_NET2USER_RESP; - break; - case LAPD_MODE_NETWORK: - dl->cr.loc2rem.cmd = CR_NET2USER_CMD; - dl->cr.loc2rem.resp = CR_NET2USER_RESP; - dl->cr.rem2loc.cmd = CR_USER2NET_CMD; - dl->cr.rem2loc.resp = CR_USER2NET_RESP; - break; - default: - return -EINVAL; - } - dl->mode = mode; - - return 0; -} - -/* send DL message with optional msgb */ -static int send_dl_l3(uint8_t prim, uint8_t op, struct lapd_msg_ctx *lctx, - struct msgb *msg) -{ - struct lapd_datalink *dl = lctx->dl; - struct osmo_dlsap_prim dp; - - osmo_prim_init(&dp.oph, 0, prim, op, msg); - return dl->send_dlsap(&dp, lctx); -} - -/* send simple DL message */ -static inline int send_dl_simple(uint8_t prim, uint8_t op, - struct lapd_msg_ctx *lctx) -{ - struct msgb *msg = lapd_msgb_alloc(0, "DUMMY"); - - return send_dl_l3(prim, op, lctx, msg); -} - -/* send MDL-ERROR INDICATION */ -static int mdl_error(uint8_t cause, struct lapd_msg_ctx *lctx) -{ - struct lapd_datalink *dl = lctx->dl; - struct osmo_dlsap_prim dp; - - LOGP(DLLAPD, LOGL_NOTICE, "sending MDL-ERROR-IND cause %d\n", - cause); - osmo_prim_init(&dp.oph, 0, PRIM_MDL_ERROR, PRIM_OP_INDICATION, NULL); - dp.u.error_ind.cause = cause; - return dl->send_dlsap(&dp, lctx); -} - -/* send UA response */ -static int lapd_send_ua(struct lapd_msg_ctx *lctx, uint8_t len, uint8_t *data) -{ - struct msgb *msg = lapd_msgb_alloc(len, "LAPD UA"); - struct lapd_msg_ctx nctx; - struct lapd_datalink *dl = lctx->dl; - - memcpy(&nctx, lctx, sizeof(nctx)); - msg->l3h = msgb_put(msg, len); - if (len) - memcpy(msg->l3h, data, len); - /* keep nctx.ldp */ - /* keep nctx.sapi */ - /* keep nctx.tei */ - nctx.cr = dl->cr.loc2rem.resp; - nctx.format = LAPD_FORM_U; - nctx.s_u = LAPD_U_UA; - /* keep nctx.p_f */ - nctx.length = len; - nctx.more = 0; - - return dl->send_ph_data_req(&nctx, msg); -} - -/* send DM response */ -static int lapd_send_dm(struct lapd_msg_ctx *lctx) -{ - struct msgb *msg = lapd_msgb_alloc(0, "LAPD DM"); - struct lapd_msg_ctx nctx; - struct lapd_datalink *dl = lctx->dl; - - memcpy(&nctx, lctx, sizeof(nctx)); - /* keep nctx.ldp */ - /* keep nctx.sapi */ - /* keep nctx.tei */ - nctx.cr = dl->cr.loc2rem.resp; - nctx.format = LAPD_FORM_U; - nctx.s_u = LAPD_U_DM; - /* keep nctx.p_f */ - nctx.length = 0; - nctx.more = 0; - - return dl->send_ph_data_req(&nctx, msg); -} - -/* send RR response / command */ -static int lapd_send_rr(struct lapd_msg_ctx *lctx, uint8_t f_bit, uint8_t cmd) -{ - struct msgb *msg = lapd_msgb_alloc(0, "LAPD RR"); - struct lapd_msg_ctx nctx; - struct lapd_datalink *dl = lctx->dl; - - memcpy(&nctx, lctx, sizeof(nctx)); - /* keep nctx.ldp */ - /* keep nctx.sapi */ - /* keep nctx.tei */ - nctx.cr = (cmd) ? dl->cr.loc2rem.cmd : dl->cr.loc2rem.resp; - nctx.format = LAPD_FORM_S; - nctx.s_u = LAPD_S_RR; - nctx.p_f = f_bit; - nctx.n_recv = dl->v_recv; - nctx.length = 0; - nctx.more = 0; - - return dl->send_ph_data_req(&nctx, msg); -} - -/* send RNR response / command */ -static int lapd_send_rnr(struct lapd_msg_ctx *lctx, uint8_t f_bit, uint8_t cmd) -{ - struct msgb *msg = lapd_msgb_alloc(0, "LAPD RNR"); - struct lapd_msg_ctx nctx; - struct lapd_datalink *dl = lctx->dl; - - memcpy(&nctx, lctx, sizeof(nctx)); - /* keep nctx.ldp */ - /* keep nctx.sapi */ - /* keep nctx.tei */ - nctx.cr = (cmd) ? dl->cr.loc2rem.cmd : dl->cr.loc2rem.resp; - nctx.format = LAPD_FORM_S; - nctx.s_u = LAPD_S_RNR; - nctx.p_f = f_bit; - nctx.n_recv = dl->v_recv; - nctx.length = 0; - nctx.more = 0; - - return dl->send_ph_data_req(&nctx, msg); -} - -/* send REJ response */ -static int lapd_send_rej(struct lapd_msg_ctx *lctx, uint8_t f_bit) -{ - struct msgb *msg = lapd_msgb_alloc(0, "LAPD REJ"); - struct lapd_msg_ctx nctx; - struct lapd_datalink *dl = lctx->dl; - - memcpy(&nctx, lctx, sizeof(nctx)); - /* keep nctx.ldp */ - /* keep nctx.sapi */ - /* keep nctx.tei */ - nctx.cr = dl->cr.loc2rem.resp; - nctx.format = LAPD_FORM_S; - nctx.s_u = LAPD_S_REJ; - nctx.p_f = f_bit; - nctx.n_recv = dl->v_recv; - nctx.length = 0; - nctx.more = 0; - - return dl->send_ph_data_req(&nctx, msg); -} - -/* resend SABM or DISC message */ -static int lapd_send_resend(struct lapd_datalink *dl) -{ - struct msgb *msg; - uint8_t h = do_mod(dl->v_send, dl->range_hist); - int length = dl->tx_hist[h].msg->len; - struct lapd_msg_ctx nctx; - - /* assemble message */ - memcpy(&nctx, &dl->lctx, sizeof(nctx)); - /* keep nctx.ldp */ - /* keep nctx.sapi */ - /* keep nctx.tei */ - nctx.cr = dl->cr.loc2rem.cmd; - nctx.format = LAPD_FORM_U; - if (dl->state == LAPD_STATE_SABM_SENT) - nctx.s_u = (dl->use_sabme) ? LAPD_U_SABME : LAPD_U_SABM; - else - nctx.s_u = LAPD_U_DISC; - nctx.p_f = 1; - nctx.length = length; - nctx.more = 0; - - /* Resend SABM/DISC from tx_hist */ - msg = lapd_msgb_alloc(length, "LAPD resend"); - msg->l3h = msgb_put(msg, length); - if (length) - memcpy(msg->l3h, dl->tx_hist[h].msg->data, length); - - return dl->send_ph_data_req(&nctx, msg); -} - -/* reestablish link */ -static int lapd_reestablish(struct lapd_datalink *dl) -{ - struct osmo_dlsap_prim dp; - struct msgb *msg; - - msg = lapd_msgb_alloc(0, "DUMMY"); - osmo_prim_init(&dp.oph, 0, PRIM_DL_EST, PRIM_OP_REQUEST, msg); - - return lapd_est_req(&dp, &dl->lctx); -} - -/* Timer callback on T200 expiry */ -static void lapd_t200_cb(void *data) -{ - struct lapd_datalink *dl = data; - - LOGP(DLLAPD, LOGL_INFO, "Timeout T200 (%p) state=%d\n", dl, - (int) dl->state); - - switch (dl->state) { - case LAPD_STATE_SABM_SENT: - /* 5.4.1.3 */ - if (dl->retrans_ctr + 1 >= dl->n200_est_rel + 1) { - /* send RELEASE INDICATION to L3 */ - send_dl_simple(PRIM_DL_REL, PRIM_OP_INDICATION, - &dl->lctx); - /* send MDL ERROR INIDCATION to L3 */ - mdl_error(MDL_CAUSE_T200_EXPIRED, &dl->lctx); - /* flush tx and send buffers */ - lapd_dl_flush_tx(dl); - lapd_dl_flush_send(dl); - /* go back to idle state */ - lapd_dl_newstate(dl, LAPD_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 */ - lapd_send_resend(dl); - /* increment re-transmission counter */ - dl->retrans_ctr++; - /* restart T200 (PH-READY-TO-SEND) */ - lapd_start_t200(dl); - break; - case LAPD_STATE_DISC_SENT: - /* 5.4.4.3 */ - if (dl->retrans_ctr + 1 >= dl->n200_est_rel + 1) { - /* send RELEASE INDICATION to L3 */ - send_dl_simple(PRIM_DL_REL, PRIM_OP_CONFIRM, &dl->lctx); - /* send MDL ERROR INIDCATION to L3 */ - mdl_error(MDL_CAUSE_T200_EXPIRED, &dl->lctx); - /* flush tx and send buffers */ - lapd_dl_flush_tx(dl); - lapd_dl_flush_send(dl); - /* go back to idle state */ - lapd_dl_newstate(dl, LAPD_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 */ - lapd_send_resend(dl); - /* increment re-transmission counter */ - dl->retrans_ctr++; - /* restart T200 (PH-READY-TO-SEND) */ - lapd_start_t200(dl); - break; - case LAPD_STATE_MF_EST: - /* 5.5.7 */ - dl->retrans_ctr = 0; - lapd_dl_newstate(dl, LAPD_STATE_TIMER_RECOV); - /* fall through */ - case LAPD_STATE_TIMER_RECOV: - dl->retrans_ctr++; - if (dl->retrans_ctr < dl->n200) { - uint8_t vs = sub_mod(dl->v_send, 1, dl->v_range); - uint8_t h = do_mod(vs, dl->range_hist); - /* retransmit I frame (V_s-1) with P=1, if any */ - if (dl->tx_hist[h].msg) { - struct msgb *msg; - int length = dl->tx_hist[h].msg->len; - struct lapd_msg_ctx nctx; - - LOGP(DLLAPD, LOGL_INFO, "retransmit last frame" - " V(S)=%d\n", vs); - /* Create I frame (segment) from tx_hist */ - memcpy(&nctx, &dl->lctx, sizeof(nctx)); - /* keep nctx.ldp */ - /* keep nctx.sapi */ - /* keep nctx.tei */ - nctx.cr = dl->cr.loc2rem.cmd; - nctx.format = LAPD_FORM_I; - nctx.p_f = 1; - nctx.n_send = vs; - nctx.n_recv = dl->v_recv; - nctx.length = length; - nctx.more = dl->tx_hist[h].more; - msg = lapd_msgb_alloc(length, "LAPD I resend"); - msg->l3h = msgb_put(msg, length); - memcpy(msg->l3h, dl->tx_hist[h].msg->data, - length); - dl->send_ph_data_req(&nctx, msg); - } else { - /* OR send appropriate supervision frame with P=1 */ - if (!dl->own_busy && !dl->seq_err_cond) { - lapd_send_rr(&dl->lctx, 1, 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) { - lapd_send_rnr(&dl->lctx, 1, 1); - } else { - LOGP(DLLAPD, LOGL_INFO, "unhandled, " - "pls. fix\n"); - } - } - /* restart T200 (PH-READY-TO-SEND) */ - lapd_start_t200(dl); - } else { - /* send MDL ERROR INIDCATION to L3 */ - mdl_error(MDL_CAUSE_T200_EXPIRED, &dl->lctx); - /* reestablish */ - if (!dl->reestablish) - break; - LOGP(DLLAPD, LOGL_NOTICE, "N200 reached, performing " - "reestablishment.\n"); - lapd_reestablish(dl); - } - break; - default: - LOGP(DLLAPD, LOGL_INFO, "T200 expired in unexpected " - "dl->state %d\n", (int) dl->state); - } -} - -/* Timer callback on T203 expiry */ -static void lapd_t203_cb(void *data) -{ - struct lapd_datalink *dl = data; - - LOGP(DLLAPD, LOGL_INFO, "Timeout T203 (%p) state=%d\n", dl, - (int) dl->state); - - if (dl->state != LAPD_STATE_MF_EST) { - LOGP(DLLAPD, LOGL_ERROR, "T203 fired outside MF EST state, " - "please fix!\n"); - return; - } - - /* set retransmission counter to 0 */ - dl->retrans_ctr = 0; - /* enter timer recovery state */ - lapd_dl_newstate(dl, LAPD_STATE_TIMER_RECOV); - /* transmit a supervisory command with P bit set to 1 as follows: */ - if (!dl->own_busy) { - LOGP(DLLAPD, LOGL_INFO, "transmit an RR poll command\n"); - /* Send RR with P=1 */ - lapd_send_rr(&dl->lctx, 1, 1); - } else { - LOGP(DLLAPD, LOGL_INFO, "transmit an RNR poll command\n"); - /* Send RNR with P=1 */ - lapd_send_rnr(&dl->lctx, 1, 1); - } - /* start T200 */ - lapd_start_t200(dl); -} - -/* 5.5.3.1: Common function to acknowlege frames up to the given N(R) value */ -static void lapd_acknowledge(struct lapd_msg_ctx *lctx) -{ - struct lapd_datalink *dl = lctx->dl; - uint8_t nr = lctx->n_recv; - int s = 0, rej = 0, t200_reset = 0; - int i, h; - - /* supervisory frame ? */ - if (lctx->format == LAPD_FORM_S) - s = 1; - /* REJ frame ? */ - if (s && lctx->s_u == LAPD_S_REJ) - rej = 1; - - /* Flush all transmit buffers of acknowledged frames */ - for (i = dl->v_ack; i != nr; i = inc_mod(i, dl->v_range)) { - h = do_mod(i, dl->range_hist); - if (dl->tx_hist[h].msg) { - msgb_free(dl->tx_hist[h].msg); - dl->tx_hist[h].msg = NULL; - LOGP(DLLAPD, LOGL_INFO, "ack frame %d\n", i); - } - } - - if (dl->state != LAPD_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)) { - t200_reset = 1; - lapd_stop_t200(dl); - /* 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_mod(nr, dl->v_ack, dl->v_range) - > sub_mod(dl->v_send, dl->v_ack, dl->v_range)) { - LOGP(DLLAPD, LOGL_NOTICE, "N(R) sequence error\n"); - mdl_error(MDL_CAUSE_SEQ_ERR, lctx); - } - } - - /* V(A) shall be set to the value of N(R) */ - dl->v_ack = nr; - - /* If T200 has been stopped 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_hist[sub_mod(dl->v_send, 1, dl->range_hist)].msg) { - LOGP(DLLAPD, LOGL_INFO, "start T200, due to unacked I " - "frame(s)\n"); - lapd_start_t200(dl); - } - } - - /* This also does a restart, when I or S frame is received */ - - /* Stop T203, if running */ - lapd_stop_t203(dl); - /* Start T203, if T200 is not running in MF EST state, if enabled */ - if (!osmo_timer_pending(&dl->t200) - && (dl->t203_sec || dl->t203_usec) - && (dl->state == LAPD_STATE_MF_EST)) { - lapd_start_t203(dl); - } -} - -/* L1 -> L2 */ - -/* Receive a LAPD U (Unnumbered) message from L1 */ -static int lapd_rx_u(struct msgb *msg, struct lapd_msg_ctx *lctx) -{ - struct lapd_datalink *dl = lctx->dl; - int length = lctx->length; - int rc = 0; - uint8_t prim, op; - - switch (lctx->s_u) { - case LAPD_U_SABM: - case LAPD_U_SABME: - prim = PRIM_DL_EST; - op = PRIM_OP_INDICATION; - - LOGP(DLLAPD, LOGL_INFO, "SABM(E) received in state %s\n", - lapd_state_names[dl->state]); - /* 5.7.1 */ - dl->seq_err_cond = 0; - /* G.2.2 Wrong value of the C/R bit */ - if (lctx->cr == dl->cr.rem2loc.resp) { - LOGP(DLLAPD, LOGL_NOTICE, "SABM response error\n"); - msgb_free(msg); - mdl_error(MDL_CAUSE_FRM_UNIMPL, lctx); - return -EINVAL; - } - - /* G.4.5 If SABM is received with L>N201 or with M bit - * set, AN MDL-ERROR-INDICATION is sent to MM. - */ - if (lctx->more || length > lctx->n201) { - LOGP(DLLAPD, LOGL_NOTICE, "SABM too large error\n"); - msgb_free(msg); - mdl_error(MDL_CAUSE_UFRM_INC_PARAM, lctx); - return -EIO; - } - - switch (dl->state) { - case LAPD_STATE_IDLE: - break; - case LAPD_STATE_MF_EST: - LOGP(DLLAPD, LOGL_INFO, "SABM command, multiple " - "frame established state\n"); - /* If link is lost on the remote side, we start over - * and send DL-ESTABLISH indication again. */ - if (dl->v_send != dl->v_recv) { - LOGP(DLLAPD, LOGL_INFO, "Remote reestablish\n"); - mdl_error(MDL_CAUSE_SABM_MF, lctx); - break; - } - /* Ignore SABM if content differs from first SABM. */ - if (dl->mode == LAPD_MODE_NETWORK && length - && dl->cont_res) { -#ifdef TEST_CONTENT_RESOLUTION_NETWORK - dl->cont_res->data[0] ^= 0x01; -#endif - if (memcmp(dl->cont_res, msg->data, length)) { - LOGP(DLLAPD, LOGL_INFO, "Another SABM " - "with diffrent content - " - "ignoring!\n"); - msgb_free(msg); - return 0; - } - } - /* send UA again */ - lapd_send_ua(lctx, length, msg->l3h); - msgb_free(msg); - return 0; - case LAPD_STATE_DISC_SENT: - /* 5.4.6.2 send DM with F=P */ - lapd_send_dm(lctx); - /* stop Timer T200 */ - lapd_stop_t200(dl); - msgb_free(msg); - return send_dl_simple(prim, op, lctx); - default: - /* collision: Send UA, but still wait for rx UA, then - * change to MF_EST state. - */ - /* check for contention resoultion */ - if (dl->tx_hist[0].msg && dl->tx_hist[0].msg->len) { - LOGP(DLLAPD, LOGL_NOTICE, "SABM not allowed " - "during contention resolution\n"); - mdl_error(MDL_CAUSE_SABM_INFO_NOTALL, lctx); - } - lapd_send_ua(lctx, length, msg->l3h); - msgb_free(msg); - return 0; - } - /* save message context for further use */ - memcpy(&dl->lctx, lctx, sizeof(dl->lctx)); -#ifndef TEST_CONTENT_RESOLUTION_NETWORK - /* send UA response */ - lapd_send_ua(lctx, length, msg->l3h); -#endif - /* set Vs, Vr and Va to 0 */ - dl->v_send = dl->v_recv = dl->v_ack = 0; - /* clear tx_hist */ - lapd_dl_flush_hist(dl); - /* enter multiple-frame-established state */ - lapd_dl_newstate(dl, LAPD_STATE_MF_EST); - /* store content resolution data on network side - * Note: cont_res will be removed when changing state again, - * so it must be allocated AFTER lapd_dl_newstate(). */ - if (dl->mode == LAPD_MODE_NETWORK && length) { - dl->cont_res = lapd_msgb_alloc(length, "CONT RES"); - memcpy(msgb_put(dl->cont_res, length), msg->l3h, - length); - LOGP(DLLAPD, LOGL_NOTICE, "Store content res.\n"); - } - /* send notification to L3 */ - if (length == 0) { - /* 5.4.1.2 Normal establishment procedures */ - rc = send_dl_simple(prim, op, lctx); - msgb_free(msg); - } else { - /* 5.4.1.4 Contention resolution establishment */ - rc = send_dl_l3(prim, op, lctx, msg); - } - break; - case LAPD_U_DM: - LOGP(DLLAPD, LOGL_INFO, "DM received in state %s\n", - lapd_state_names[dl->state]); - /* G.2.2 Wrong value of the C/R bit */ - if (lctx->cr == dl->cr.rem2loc.cmd) { - LOGP(DLLAPD, LOGL_NOTICE, "DM command error\n"); - msgb_free(msg); - mdl_error(MDL_CAUSE_FRM_UNIMPL, lctx); - return -EINVAL; - } - if (!lctx->p_f) { - /* 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 LAPD_STATE_SABM_SENT: - break; - case LAPD_STATE_MF_EST: - if (lctx->p_f) { - LOGP(DLLAPD, LOGL_INFO, "unsolicited DM " - "response\n"); - mdl_error(MDL_CAUSE_UNSOL_DM_RESP, lctx); - } else { - LOGP(DLLAPD, LOGL_INFO, "unsolicited DM " - "response, multiple frame established " - "state\n"); - mdl_error(MDL_CAUSE_UNSOL_DM_RESP_MF, lctx); - /* reestablish */ - if (!dl->reestablish) { - msgb_free(msg); - return 0; - } - LOGP(DLLAPD, LOGL_NOTICE, "Performing " - "reestablishment.\n"); - lapd_reestablish(dl); - } - msgb_free(msg); - return 0; - case LAPD_STATE_TIMER_RECOV: - /* FP = 0 (DM is normal in case PF = 1) */ - if (!lctx->p_f) { - LOGP(DLLAPD, LOGL_INFO, "unsolicited DM " - "response, multiple frame established " - "state\n"); - mdl_error(MDL_CAUSE_UNSOL_DM_RESP_MF, lctx); - msgb_free(msg); - /* reestablish */ - if (!dl->reestablish) - return 0; - LOGP(DLLAPD, LOGL_NOTICE, "Performing " - "reestablishment.\n"); - return lapd_reestablish(dl); - } - break; - case LAPD_STATE_DISC_SENT: - /* stop Timer T200 */ - lapd_stop_t200(dl); - /* go to idle state */ - lapd_dl_flush_tx(dl); - lapd_dl_flush_send(dl); - lapd_dl_newstate(dl, LAPD_STATE_IDLE); - rc = send_dl_simple(PRIM_DL_REL, PRIM_OP_CONFIRM, lctx); - msgb_free(msg); - return 0; - case LAPD_STATE_IDLE: - /* 5.4.5 all other frame types shall be discarded */ - default: - LOGP(DLLAPD, LOGL_INFO, "unsolicited DM response! " - "(discarding)\n"); - msgb_free(msg); - return 0; - } - /* stop timer T200 */ - lapd_stop_t200(dl); - /* go to idle state */ - lapd_dl_newstate(dl, LAPD_STATE_IDLE); - rc = send_dl_simple(PRIM_DL_REL, PRIM_OP_INDICATION, lctx); - msgb_free(msg); - break; - case LAPD_U_UI: - LOGP(DLLAPD, LOGL_INFO, "UI received\n"); - /* G.2.2 Wrong value of the C/R bit */ - if (lctx->cr == dl->cr.rem2loc.resp) { - LOGP(DLLAPD, LOGL_NOTICE, "UI indicates response " - "error\n"); - msgb_free(msg); - mdl_error(MDL_CAUSE_FRM_UNIMPL, lctx); - return -EINVAL; - } - - /* G.4.5 If UI is received with L>N201 or with M bit - * set, AN MDL-ERROR-INDICATION is sent to MM. - */ - if (length > lctx->n201 || lctx->more) { - LOGP(DLLAPD, LOGL_NOTICE, "UI too large error " - "(%d > N201(%d) or M=%d)\n", length, - lctx->n201, lctx->more); - msgb_free(msg); - mdl_error(MDL_CAUSE_UFRM_INC_PARAM, lctx); - return -EIO; - } - - /* do some length checks */ - if (length == 0) { - /* 5.3.3 UI frames received with the length indicator - * set to "0" shall be ignored - */ - LOGP(DLLAPD, LOGL_INFO, "length=0 (discarding)\n"); - msgb_free(msg); - return 0; - } - rc = send_dl_l3(PRIM_DL_UNIT_DATA, PRIM_OP_INDICATION, lctx, - msg); - break; - case LAPD_U_DISC: - prim = PRIM_DL_REL; - op = PRIM_OP_INDICATION; - - LOGP(DLLAPD, LOGL_INFO, "DISC received in state %s\n", - lapd_state_names[dl->state]); - /* flush tx and send buffers */ - lapd_dl_flush_tx(dl); - lapd_dl_flush_send(dl); - /* 5.7.1 */ - dl->seq_err_cond = 0; - /* G.2.2 Wrong value of the C/R bit */ - if (lctx->cr == dl->cr.rem2loc.resp) { - LOGP(DLLAPD, LOGL_NOTICE, "DISC response error\n"); - msgb_free(msg); - mdl_error(MDL_CAUSE_FRM_UNIMPL, lctx); - return -EINVAL; - } - if (length > 0 || lctx->more) { - /* 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(DLLAPD, LOGL_NOTICE, - "U frame iwth incorrect parameters "); - msgb_free(msg); - mdl_error(MDL_CAUSE_UFRM_INC_PARAM, lctx); - return -EIO; - } - switch (dl->state) { - case LAPD_STATE_IDLE: - LOGP(DLLAPD, LOGL_INFO, "DISC in idle state\n"); - /* send DM with F=P */ - msgb_free(msg); - return lapd_send_dm(lctx); - case LAPD_STATE_SABM_SENT: - LOGP(DLLAPD, LOGL_INFO, "DISC in SABM state\n"); - /* 5.4.6.2 send DM with F=P */ - lapd_send_dm(lctx); - /* stop Timer T200 */ - lapd_stop_t200(dl); - /* go to idle state */ - lapd_dl_newstate(dl, LAPD_STATE_IDLE); - msgb_free(msg); - return send_dl_simple(PRIM_DL_REL, PRIM_OP_INDICATION, - lctx); - case LAPD_STATE_MF_EST: - case LAPD_STATE_TIMER_RECOV: - LOGP(DLLAPD, LOGL_INFO, "DISC in est state\n"); - break; - case LAPD_STATE_DISC_SENT: - LOGP(DLLAPD, LOGL_INFO, "DISC in disc state\n"); - prim = PRIM_DL_REL; - op = PRIM_OP_CONFIRM; - break; - default: - lapd_send_ua(lctx, length, msg->l3h); - msgb_free(msg); - return 0; - } - /* send UA response */ - lapd_send_ua(lctx, length, msg->l3h); - /* stop Timer T200 */ - lapd_stop_t200(dl); - /* enter idle state, keep tx-buffer with UA response */ - lapd_dl_newstate(dl, LAPD_STATE_IDLE); - /* send notification to L3 */ - rc = send_dl_simple(prim, op, lctx); - msgb_free(msg); - break; - case LAPD_U_UA: - LOGP(DLLAPD, LOGL_INFO, "UA received in state %s\n", - lapd_state_names[dl->state]); - /* G.2.2 Wrong value of the C/R bit */ - if (lctx->cr == dl->cr.rem2loc.cmd) { - LOGP(DLLAPD, LOGL_NOTICE, "UA indicates command " - "error\n"); - msgb_free(msg); - mdl_error(MDL_CAUSE_FRM_UNIMPL, lctx); - return -EINVAL; - } - - /* G.4.5 If UA is received with L>N201 or with M bit - * set, AN MDL-ERROR-INDICATION is sent to MM. - */ - if (lctx->more || length > lctx->n201) { - LOGP(DLLAPD, LOGL_NOTICE, "UA too large error\n"); - msgb_free(msg); - mdl_error(MDL_CAUSE_UFRM_INC_PARAM, lctx); - return -EIO; - } - - if (!lctx->p_f) { - /* 5.4.1.2 A UA response with the F bit set to "0" - * shall be ignored. - */ - LOGP(DLLAPD, LOGL_INFO, "F=0 (discarding)\n"); - msgb_free(msg); - return 0; - } - switch (dl->state) { - case LAPD_STATE_SABM_SENT: - break; - case LAPD_STATE_MF_EST: - case LAPD_STATE_TIMER_RECOV: - LOGP(DLLAPD, LOGL_INFO, "unsolicited UA response! " - "(discarding)\n"); - mdl_error(MDL_CAUSE_UNSOL_UA_RESP, lctx); - msgb_free(msg); - return 0; - case LAPD_STATE_DISC_SENT: - LOGP(DLLAPD, LOGL_INFO, "UA in disconnect state\n"); - /* stop Timer T200 */ - lapd_stop_t200(dl); - /* go to idle state */ - lapd_dl_flush_tx(dl); - lapd_dl_flush_send(dl); - lapd_dl_newstate(dl, LAPD_STATE_IDLE); - rc = send_dl_simple(PRIM_DL_REL, PRIM_OP_CONFIRM, lctx); - msgb_free(msg); - return 0; - case LAPD_STATE_IDLE: - /* 5.4.5 all other frame types shall be discarded */ - default: - LOGP(DLLAPD, LOGL_INFO, "unsolicited UA response! " - "(discarding)\n"); - msgb_free(msg); - return 0; - } - LOGP(DLLAPD, LOGL_INFO, "UA in SABM state\n"); - /* stop Timer T200 */ - lapd_stop_t200(dl); - /* compare UA with SABME if contention resolution is applied */ - if (dl->tx_hist[0].msg->len) { - if (length != (dl->tx_hist[0].msg->len) - || !!memcmp(dl->tx_hist[0].msg->data, msg->l3h, - length)) { - LOGP(DLLAPD, LOGL_INFO, "**** UA response " - "mismatches ****\n"); - rc = send_dl_simple(PRIM_DL_REL, - PRIM_OP_INDICATION, lctx); - msgb_free(msg); - /* go to idle state */ - lapd_dl_flush_tx(dl); - lapd_dl_flush_send(dl); - lapd_dl_newstate(dl, LAPD_STATE_IDLE); - return 0; - } - } - /* set Vs, Vr and Va to 0 */ - dl->v_send = dl->v_recv = dl->v_ack = 0; - /* clear tx_hist */ - lapd_dl_flush_hist(dl); - /* enter multiple-frame-established state */ - lapd_dl_newstate(dl, LAPD_STATE_MF_EST); - /* send outstanding frames, if any (resume / reconnect) */ - lapd_send_i(lctx, __LINE__); - /* send notification to L3 */ - rc = send_dl_simple(PRIM_DL_EST, PRIM_OP_CONFIRM, lctx); - msgb_free(msg); - break; - case LAPD_U_FRMR: - LOGP(DLLAPD, LOGL_NOTICE, "Frame reject received\n"); - /* send MDL ERROR INIDCATION to L3 */ - mdl_error(MDL_CAUSE_FRMR, lctx); - msgb_free(msg); - /* reestablish */ - if (!dl->reestablish) - break; - LOGP(DLLAPD, LOGL_NOTICE, "Performing reestablishment.\n"); - rc = lapd_reestablish(dl); - break; - default: - /* G.3.1 */ - LOGP(DLLAPD, LOGL_NOTICE, "Unnumbered frame not allowed.\n"); - msgb_free(msg); - mdl_error(MDL_CAUSE_FRM_UNIMPL, lctx); - return -EINVAL; - } - return rc; -} - -/* Receive a LAPD S (Supervisory) message from L1 */ -static int lapd_rx_s(struct msgb *msg, struct lapd_msg_ctx *lctx) -{ - struct lapd_datalink *dl = lctx->dl; - int length = lctx->length; - - if (length > 0 || lctx->more) { - /* 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(DLLAPD, LOGL_NOTICE, - "S frame with incorrect parameters\n"); - msgb_free(msg); - mdl_error(MDL_CAUSE_SFRM_INC_PARAM, lctx); - return -EIO; - } - - if (lctx->cr == dl->cr.rem2loc.resp - && lctx->p_f - && dl->state != LAPD_STATE_TIMER_RECOV) { - /* 5.4.2.2: Inidcate error on supervisory reponse F=1 */ - LOGP(DLLAPD, LOGL_NOTICE, "S frame response with F=1 error\n"); - mdl_error(MDL_CAUSE_UNSOL_SPRV_RESP, lctx); - } - - switch (dl->state) { - case LAPD_STATE_IDLE: - /* if P=1, respond DM with F=1 (5.2.2) */ - /* 5.4.5 all other frame types shall be discarded */ - if (lctx->p_f) - lapd_send_dm(lctx); /* F=P */ - /* fall though */ - case LAPD_STATE_SABM_SENT: - case LAPD_STATE_DISC_SENT: - LOGP(DLLAPD, LOGL_NOTICE, "S frame ignored in this state\n"); - msgb_free(msg); - return 0; - } - switch (lctx->s_u) { - case LAPD_S_RR: - LOGP(DLLAPD, LOGL_INFO, "RR received in state %s\n", - lapd_state_names[dl->state]); - /* 5.5.3.1: Acknowlege all tx frames up the the N(R)-1 */ - lapd_acknowledge(lctx); - - /* 5.5.3.2 */ - if (lctx->cr == dl->cr.rem2loc.cmd - && lctx->p_f) { - if (!dl->own_busy && !dl->seq_err_cond) { - LOGP(DLLAPD, LOGL_INFO, "RR frame command " - "with polling bit set and we are not " - "busy, so we reply with RR frame " - "response\n"); - lapd_send_rr(lctx, 1, 0); - /* 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(DLLAPD, LOGL_INFO, "RR frame command " - "with polling bit set and we are busy, " - "so we reply with RR frame response\n"); - lapd_send_rnr(lctx, 1, 0); - } - } else if (lctx->cr == dl->cr.rem2loc.resp - && lctx->p_f - && dl->state == LAPD_STATE_TIMER_RECOV) { - LOGP(DLLAPD, 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 = lctx->n_recv; - /* stop Timer T200 */ - lapd_stop_t200(dl); - /* 5.5.7 Clear timer recovery condition */ - lapd_dl_newstate(dl, LAPD_STATE_MF_EST); - } - /* Send message, if possible due to acknowledged data */ - lapd_send_i(lctx, __LINE__); - - break; - case LAPD_S_RNR: - LOGP(DLLAPD, LOGL_INFO, "RNR received in state %s\n", - lapd_state_names[dl->state]); - /* 5.5.3.1: Acknowlege all tx frames up the the N(R)-1 */ - lapd_acknowledge(lctx); - - /* 5.5.5 */ - /* Set peer receiver busy condition */ - dl->peer_busy = 1; - - if (lctx->p_f) { - if (lctx->cr == dl->cr.rem2loc.cmd) { - if (!dl->own_busy) { - LOGP(DLLAPD, LOGL_INFO, "RNR poll " - "command and we are not busy, " - "so we reply with RR final " - "response\n"); - /* Send RR with F=1 */ - lapd_send_rr(lctx, 1, 0); - } else { - LOGP(DLLAPD, LOGL_INFO, "RNR poll " - "command and we are busy, so " - "we reply with RNR final " - "response\n"); - /* Send RNR with F=1 */ - lapd_send_rnr(lctx, 1, 0); - } - } else if (dl->state == LAPD_STATE_TIMER_RECOV) { - LOGP(DLLAPD, LOGL_INFO, "RNR poll response " - "and we in timer recovery state, so " - "we leave that state\n"); - /* 5.5.7 Clear timer recovery condition */ - lapd_dl_newstate(dl, LAPD_STATE_MF_EST); - /* V(S) to the N(R) in the RNR frame */ - dl->v_send = lctx->n_recv; - } - } else - LOGP(DLLAPD, LOGL_INFO, "RNR not polling/final state " - "received\n"); - - /* Send message, if possible due to acknowledged data */ - lapd_send_i(lctx, __LINE__); - - break; - case LAPD_S_REJ: - LOGP(DLLAPD, LOGL_INFO, "REJ received in state %s\n", - lapd_state_names[dl->state]); - /* 5.5.3.1: Acknowlege all tx frames up the the N(R)-1 */ - lapd_acknowledge(lctx); - - /* 5.5.4.1 */ - if (dl->state != LAPD_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 = lctx->n_recv; - /* stop Timer T200 */ - lapd_stop_t200(dl); - /* 5.5.3.2 */ - if (lctx->cr == dl->cr.rem2loc.cmd && lctx->p_f) { - if (!dl->own_busy && !dl->seq_err_cond) { - LOGP(DLLAPD, 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"); - lapd_send_rr(lctx, 1, 0); - /* 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(DLLAPD, LOGL_INFO, "REJ poll " - "command not in timer recovery " - "state and in own busy " - "condition received, so we " - "respond with RNR final " - "response\n"); - lapd_send_rnr(lctx, 1, 0); - } - } else - LOGP(DLLAPD, LOGL_INFO, "REJ response or not " - "polling command not in timer recovery " - "state received\n"); - /* send MDL ERROR INIDCATION to L3 */ - if (lctx->cr == dl->cr.rem2loc.resp && lctx->p_f) { - mdl_error(MDL_CAUSE_UNSOL_SPRV_RESP, lctx); - } - - } else if (lctx->cr == dl->cr.rem2loc.resp && lctx->p_f) { - LOGP(DLLAPD, LOGL_INFO, "REJ poll response in timer " - "recovery state received\n"); - /* 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 = lctx->n_recv; - /* stop Timer T200 */ - lapd_stop_t200(dl); - /* 5.5.7 Clear timer recovery condition */ - lapd_dl_newstate(dl, LAPD_STATE_MF_EST); - } 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 = lctx->n_recv; - /* 5.5.3.2 */ - if (lctx->cr == dl->cr.rem2loc.cmd && lctx->p_f) { - if (!dl->own_busy && !dl->seq_err_cond) { - LOGP(DLLAPD, LOGL_INFO, "REJ poll " - "command in timer recovery " - "state and not in own busy " - "condition received, so we " - "respond with RR final " - "response\n"); - lapd_send_rr(lctx, 1, 0); - /* 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(DLLAPD, LOGL_INFO, "REJ poll " - "command in timer recovery " - "state and in own busy " - "condition received, so we " - "respond with RNR final " - "response\n"); - lapd_send_rnr(lctx, 1, 0); - } - } else - LOGP(DLLAPD, 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 */ - lapd_send_i(lctx, __LINE__); - - break; - default: - /* G.3.1 */ - LOGP(DLLAPD, LOGL_NOTICE, "Supervisory frame not allowed.\n"); - msgb_free(msg); - mdl_error(MDL_CAUSE_FRM_UNIMPL, lctx); - return -EINVAL; - } - msgb_free(msg); - return 0; -} - -/* Receive a LAPD I (Information) message from L1 */ -static int lapd_rx_i(struct msgb *msg, struct lapd_msg_ctx *lctx) -{ - struct lapd_datalink *dl = lctx->dl; - //uint8_t nr = lctx->n_recv; - uint8_t ns = lctx->n_send; - int length = lctx->length; - int rc; - - LOGP(DLLAPD, LOGL_INFO, "I received in state %s\n", - lapd_state_names[dl->state]); - - /* G.2.2 Wrong value of the C/R bit */ - if (lctx->cr == dl->cr.rem2loc.resp) { - LOGP(DLLAPD, LOGL_NOTICE, "I frame response not allowed\n"); - msgb_free(msg); - mdl_error(MDL_CAUSE_FRM_UNIMPL, lctx); - return -EINVAL; - } - - if (length == 0 || length > lctx->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(DLLAPD, LOGL_NOTICE, "I frame length not allowed\n"); - msgb_free(msg); - mdl_error(MDL_CAUSE_IFRM_INC_LEN, lctx); - 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 (lctx->more && length < lctx->n201) { - LOGP(DLLAPD, LOGL_NOTICE, "I frame with M bit too short\n"); - msgb_free(msg); - mdl_error(MDL_CAUSE_IFRM_INC_MBITS, lctx); - return -EIO; - } - - switch (dl->state) { - case LAPD_STATE_IDLE: - /* if P=1, respond DM with F=1 (5.2.2) */ - /* 5.4.5 all other frame types shall be discarded */ - if (lctx->p_f) - lapd_send_dm(lctx); /* F=P */ - /* fall though */ - case LAPD_STATE_SABM_SENT: - case LAPD_STATE_DISC_SENT: - LOGP(DLLAPD, 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(DLLAPD, 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 != 1) { - /* FIXME: help me understand what exactly todo here - */ - dl->seq_err_cond = 1; - lapd_send_rej(lctx, lctx->p_f); - } else { - /* If there are two subsequent sequence errors received, - * ignore it. (Ignore every second subsequent error.) - * This happens if our reply with the REJ is too slow, - * so the remote gets a T200 timeout and sends another - * frame with a sequence error. - * Test showed that replying with two subsequent REJ - * messages could the remote L2 process to abort. - * Replying too slow shouldn't happen, but may happen - * over serial link between BB and LAPD. - */ - dl->seq_err_cond = 2; - } - /* Even if N(s) sequence error, acknowledge to N(R)-1 */ - /* 5.5.3.1: Acknowlege all transmitted frames up the N(R)-1 */ - lapd_acknowledge(lctx); /* V(A) is also set here */ - - /* Send message, if possible due to acknowledged data */ - lapd_send_i(lctx, __LINE__); - - return 0; - } - dl->seq_err_cond = 0; - - /* Increment receiver state */ - dl->v_recv = inc_mod(dl->v_recv, dl->v_range); - LOGP(DLLAPD, LOGL_INFO, "incrementing V(R) to %u\n", dl->v_recv); - - /* 5.5.3.1: Acknowlege all transmitted frames up the the N(R)-1 */ - lapd_acknowledge(lctx); /* 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 (!lctx->more && !dl->rcv_buffer) { - LOGP(DLLAPD, LOGL_INFO, "message in single I frame\n"); - /* send a DATA INDICATION to L3 */ - msg->len = length; - msg->tail = msg->data + length; - rc = send_dl_l3(PRIM_DL_DATA, PRIM_OP_INDICATION, lctx, - msg); - } else { - /* create rcv_buffer */ - if (!dl->rcv_buffer) { - LOGP(DLLAPD, LOGL_INFO, "message in multiple " - "I frames (first message)\n"); - dl->rcv_buffer = lapd_msgb_alloc(dl->maxf, - "LAPD RX"); - dl->rcv_buffer->l3h = dl->rcv_buffer->data; - } - /* concat. rcv_buffer */ - if (msgb_l3len(dl->rcv_buffer) + length > dl->maxf) { - LOGP(DLLAPD, LOGL_NOTICE, "Received frame " - "overflow!\n"); - } else { - memcpy(msgb_put(dl->rcv_buffer, length), - msg->l3h, length); - } - /* if the last segment was received */ - if (!lctx->more) { - LOGP(DLLAPD, LOGL_INFO, "message in multiple " - "I frames (last message)\n"); - rc = send_dl_l3(PRIM_DL_DATA, - PRIM_OP_INDICATION, lctx, - dl->rcv_buffer); - dl->rcv_buffer = NULL; - } else - LOGP(DLLAPD, LOGL_INFO, "message in multiple " - "I frames (next message)\n"); - msgb_free(msg); - - } - } else - LOGP(DLLAPD, LOGL_INFO, "I frame ignored during own receiver " - "busy condition\n"); - - /* Check for P bit */ - if (lctx->p_f) { - /* 5.5.2.1 */ - /* check if we are not in own receiver busy */ - if (!dl->own_busy) { - LOGP(DLLAPD, LOGL_INFO, "we are not busy, send RR\n"); - /* Send RR with F=1 */ - rc = lapd_send_rr(lctx, 1, 0); - } else { - LOGP(DLLAPD, LOGL_INFO, "we are busy, send RNR\n"); - /* Send RNR with F=1 */ - rc = lapd_send_rnr(lctx, 1, 0); - } - } 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 = lapd_send_i(lctx, __LINE__); - if (rc) { - LOGP(DLLAPD, LOGL_INFO, "we are not busy and " - "have no pending data, send RR\n"); - /* Send RR with F=0 */ - return lapd_send_rr(lctx, 0, 0); - } - /* all I or one RR is sent, we are done */ - return 0; - } else { - LOGP(DLLAPD, LOGL_INFO, "we are busy, send RNR\n"); - /* Send RNR with F=0 */ - rc = lapd_send_rnr(lctx, 0, 0); - } - } - - /* Send message, if possible due to acknowledged data */ - lapd_send_i(lctx, __LINE__); - - return rc; -} - -/* Receive a LAPD message from L1 */ -int lapd_ph_data_ind(struct msgb *msg, struct lapd_msg_ctx *lctx) -{ - int rc; - - switch (lctx->format) { - case LAPD_FORM_U: - rc = lapd_rx_u(msg, lctx); - break; - case LAPD_FORM_S: - rc = lapd_rx_s(msg, lctx); - break; - case LAPD_FORM_I: - rc = lapd_rx_i(msg, lctx); - break; - default: - LOGP(DLLAPD, LOGL_NOTICE, "unknown LAPD format\n"); - msgb_free(msg); - rc = -EINVAL; - } - return rc; -} - -/* L3 -> L2 */ - -/* send unit data */ -static int lapd_udata_req(struct osmo_dlsap_prim *dp, struct lapd_msg_ctx *lctx) -{ - struct lapd_datalink *dl = lctx->dl; - struct msgb *msg = dp->oph.msg; - struct lapd_msg_ctx nctx; - - memcpy(&nctx, lctx, sizeof(nctx)); - /* keep nctx.ldp */ - /* keep nctx.sapi */ - /* keep nctx.tei */ - nctx.cr = dl->cr.loc2rem.cmd; - nctx.format = LAPD_FORM_U; - nctx.s_u = LAPD_U_UI; - /* keep nctx.p_f */ - nctx.length = msg->len; - nctx.more = 0; - - return dl->send_ph_data_req(&nctx, msg); -} - -/* request link establishment */ -static int lapd_est_req(struct osmo_dlsap_prim *dp, struct lapd_msg_ctx *lctx) -{ - struct lapd_datalink *dl = lctx->dl; - struct msgb *msg = dp->oph.msg; - struct lapd_msg_ctx nctx; - - if (msg->len) - LOGP(DLLAPD, LOGL_INFO, "perform establishment with content " - "(SABM)\n"); - else - LOGP(DLLAPD, LOGL_INFO, "perform normal establishm. (SABM)\n"); - - /* Flush send-queue */ - /* Clear send-buffer */ - lapd_dl_flush_send(dl); - /* be sure that history is empty */ - lapd_dl_flush_hist(dl); - - /* save message context for further use */ - memcpy(&dl->lctx, lctx, sizeof(dl->lctx)); - - /* Discard partly received L3 message */ - if (dl->rcv_buffer) { - msgb_free(dl->rcv_buffer); - dl->rcv_buffer = NULL; - } - - /* assemble message */ - memcpy(&nctx, &dl->lctx, sizeof(nctx)); - /* keep nctx.ldp */ - /* keep nctx.sapi */ - /* keep nctx.tei */ - nctx.cr = dl->cr.loc2rem.cmd; - nctx.format = LAPD_FORM_U; - nctx.s_u = (dl->use_sabme) ? LAPD_U_SABME : LAPD_U_SABM; - nctx.p_f = 1; - nctx.length = msg->len; - nctx.more = 0; - - /* Transmit-buffer carries exactly one segment */ - dl->tx_hist[0].msg = lapd_msgb_alloc(msg->len, "HIST"); - msgb_put(dl->tx_hist[0].msg, msg->len); - if (msg->len) - memcpy(dl->tx_hist[0].msg->data, msg->l3h, msg->len); - dl->tx_hist[0].more = 0; - /* 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; - lapd_dl_newstate(dl, LAPD_STATE_SABM_SENT); - - /* Tramsmit and start T200 */ - dl->send_ph_data_req(&nctx, msg); - lapd_start_t200(dl); - - return 0; -} - -/* send data */ -static int lapd_data_req(struct osmo_dlsap_prim *dp, struct lapd_msg_ctx *lctx) -{ - struct lapd_datalink *dl = lctx->dl; - struct msgb *msg = dp->oph.msg; - - if (msgb_l3len(msg) == 0) { - LOGP(DLLAPD, LOGL_ERROR, - "writing an empty message is not possible.\n"); - msgb_free(msg); - return -1; - } - - LOGP(DLLAPD, LOGL_INFO, - "writing message to send-queue: l3len: %d\n", msgb_l3len(msg)); - - /* Write data into the send queue */ - msgb_enqueue(&dl->send_queue, msg); - - /* Send message, if possible */ - lapd_send_i(&dl->lctx, __LINE__); - - return 0; -} - -/* Send next I frame from queued/buffered data */ -static int lapd_send_i(struct lapd_msg_ctx *lctx, int line) -{ - struct lapd_datalink *dl = lctx->dl; - uint8_t k = dl->k; - uint8_t h; - struct msgb *msg; - int length, left; - int rc = - 1; /* we sent nothing */ - struct lapd_msg_ctx nctx; - - - LOGP(DLLAPD, LOGL_INFO, "%s() called from line %d\n", __func__, line); - - next_frame: - - if (dl->peer_busy) { - LOGP(DLLAPD, LOGL_INFO, "peer busy, not sending\n"); - return rc; - } - - if (dl->state == LAPD_STATE_TIMER_RECOV) { - LOGP(DLLAPD, 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_mod(dl->v_ack, k, dl->v_range)) { - LOGP(DLLAPD, 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; - } - - h = do_mod(dl->v_send, dl->range_hist); - - /* if we have no tx_hist yet, we create it */ - if (!dl->tx_hist[h].msg) { - /* 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(DLLAPD, 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 > lctx->n201) - length = lctx->n201; - LOGP(DLLAPD, 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, - lctx->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(DLLAPD, LOGL_INFO, "send I frame %sV(S)=%d\n", - (left > length) ? "segment " : "", dl->v_send); - - /* Create I frame (segment) and transmit-buffer content */ - msg = lapd_msgb_alloc(length, "LAPD I"); - msg->l3h = msgb_put(msg, length); - /* assemble message */ - memcpy(&nctx, &dl->lctx, sizeof(nctx)); - /* keep nctx.ldp */ - /* keep nctx.sapi */ - /* keep nctx.tei */ - nctx.cr = dl->cr.loc2rem.cmd; - nctx.format = LAPD_FORM_I; - nctx.p_f = 0; - nctx.n_send = dl->v_send; - nctx.n_recv = dl->v_recv; - nctx.length = length; - if (left > length) - nctx.more = 1; - else - nctx.more = 0; - if (length) - memcpy(msg->l3h, dl->send_buffer->l3h + dl->send_out, - length); - /* store in tx_hist */ - dl->tx_hist[h].msg = lapd_msgb_alloc(msg->len, "HIST"); - msgb_put(dl->tx_hist[h].msg, msg->len); - if (length) - memcpy(dl->tx_hist[h].msg->data, msg->l3h, msg->len); - dl->tx_hist[h].more = nctx.more; - /* Add length to track how much is already in the tx buffer */ - dl->send_out += length; - } else { - LOGP(DLLAPD, 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_hist[h].msg->len; - msg = lapd_msgb_alloc(length, "LAPD I resend"); - msg->l3h = msgb_put(msg, length); - /* assemble message */ - memcpy(&nctx, &dl->lctx, sizeof(nctx)); - /* keep nctx.ldp */ - /* keep nctx.sapi */ - /* keep nctx.tei */ - nctx.cr = dl->cr.loc2rem.cmd; - nctx.format = LAPD_FORM_I; - nctx.p_f = 0; - nctx.n_send = dl->v_send; - nctx.n_recv = dl->v_recv; - nctx.length = length; - nctx.more = dl->tx_hist[h].more; - if (length) - memcpy(msg->l3h, dl->tx_hist[h].msg->data, length); - } - - /* 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_mod(dl->v_send, dl->v_range); - - /* 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)) { - /* stop Timer T203, if running */ - lapd_stop_t203(dl); - /* start Timer T200 */ - lapd_start_t200(dl); - } - - dl->send_ph_data_req(&nctx, msg); - - rc = 0; /* we sent something */ - goto next_frame; -} - -/* request link suspension */ -static int lapd_susp_req(struct osmo_dlsap_prim *dp, struct lapd_msg_ctx *lctx) -{ - struct lapd_datalink *dl = lctx->dl; - struct msgb *msg = dp->oph.msg; - - LOGP(DLLAPD, LOGL_INFO, "perform suspension\n"); - - /* put back the send-buffer to the send-queue (first position) */ - if (dl->send_buffer) { - LOGP(DLLAPD, 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(DLLAPD, LOGL_INFO, "no frame in sendbuffer\n"); - - /* Clear transmit buffer, but keep send buffer */ - lapd_dl_flush_tx(dl); - /* Stop timers (there is no state change, so we must stop all timers */ - lapd_stop_t200(dl); - lapd_stop_t203(dl); - - msgb_free(msg); - - return send_dl_simple(PRIM_DL_SUSP, PRIM_OP_CONFIRM, &dl->lctx); -} - -/* requesst resume or reconnect of link */ -static int lapd_res_req(struct osmo_dlsap_prim *dp, struct lapd_msg_ctx *lctx) -{ - struct lapd_datalink *dl = lctx->dl; - struct msgb *msg = dp->oph.msg; - struct lapd_msg_ctx nctx; - - LOGP(DLLAPD, LOGL_INFO, "perform re-establishment (SABM) length=%d\n", - msg->len); - - /* be sure that history is empty */ - lapd_dl_flush_hist(dl); - - /* save message context for further use */ - memcpy(&dl->lctx, lctx, sizeof(dl->lctx)); - - /* Replace message in the send-buffer (reconnect) */ - if (dl->send_buffer) - msgb_free(dl->send_buffer); - dl->send_out = 0; - if (msg && msg->len) - /* Write data into the send buffer, to be sent first */ - dl->send_buffer = msg; - else - dl->send_buffer = NULL; - - /* 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 = lapd_msgb_alloc(0, "LAPD SABM"); - msg->l3h = msg->data; - /* assemble message */ - memcpy(&nctx, &dl->lctx, sizeof(nctx)); - /* keep nctx.ldp */ - /* keep nctx.sapi */ - /* keep nctx.tei */ - nctx.cr = dl->cr.loc2rem.cmd; - nctx.format = LAPD_FORM_U; - nctx.s_u = (dl->use_sabme) ? LAPD_U_SABME : LAPD_U_SABM; - nctx.p_f = 1; - nctx.length = 0; - nctx.more = 0; - - dl->tx_hist[0].msg = lapd_msgb_alloc(msg->len, "HIST"); - msgb_put(dl->tx_hist[0].msg, msg->len); - if (msg->len) - memcpy(dl->tx_hist[0].msg->data, msg->l3h, msg->len); - dl->tx_hist[0].more = 0; - /* 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; - lapd_dl_newstate(dl, LAPD_STATE_SABM_SENT); - - /* Tramsmit and start T200 */ - dl->send_ph_data_req(&nctx, msg); - lapd_start_t200(dl); - - return 0; -} - -/* requesst release of link */ -static int lapd_rel_req(struct osmo_dlsap_prim *dp, struct lapd_msg_ctx *lctx) -{ - struct lapd_datalink *dl = lctx->dl; - struct msgb *msg = dp->oph.msg; - struct lapd_msg_ctx nctx; - - /* local release */ - if (dp->u.rel_req.mode) { - LOGP(DLLAPD, LOGL_INFO, "perform local release\n"); - msgb_free(msg); - /* stop Timer T200 */ - lapd_stop_t200(dl); - /* enter idle state, T203 is stopped here, if running */ - lapd_dl_newstate(dl, LAPD_STATE_IDLE); - /* flush buffers */ - lapd_dl_flush_tx(dl); - lapd_dl_flush_send(dl); - /* send notification to L3 */ - return send_dl_simple(PRIM_DL_REL, PRIM_OP_CONFIRM, &dl->lctx); - } - - /* in case we are already disconnecting */ - if (dl->state == LAPD_STATE_DISC_SENT) - return -EBUSY; - - /* flush tx_hist */ - lapd_dl_flush_hist(dl); - - LOGP(DLLAPD, LOGL_INFO, "perform normal release (DISC)\n"); - - /* Push LAPD header on msgb */ - /* assemble message */ - memcpy(&nctx, &dl->lctx, sizeof(nctx)); - /* keep nctx.ldp */ - /* keep nctx.sapi */ - /* keep nctx.tei */ - nctx.cr = dl->cr.loc2rem.cmd; - nctx.format = LAPD_FORM_U; - nctx.s_u = LAPD_U_DISC; - nctx.p_f = 1; - nctx.length = 0; - nctx.more = 0; - - dl->tx_hist[0].msg = lapd_msgb_alloc(msg->len, "HIST"); - msgb_put(dl->tx_hist[0].msg, msg->len); - if (msg->len) - memcpy(dl->tx_hist[0].msg->data, msg->l3h, msg->len); - dl->tx_hist[0].more = 0; - /* set Vs to 0, because it is used as index when resending DISC */ - dl->v_send = 0; - - /* Set states */ - dl->own_busy = dl->peer_busy = 0; - dl->retrans_ctr = 0; - lapd_dl_newstate(dl, LAPD_STATE_DISC_SENT); - - /* Tramsmit and start T200 */ - dl->send_ph_data_req(&nctx, msg); - lapd_start_t200(dl); - - return 0; -} - -/* request release of link in idle state */ -static int lapd_rel_req_idle(struct osmo_dlsap_prim *dp, - struct lapd_msg_ctx *lctx) -{ - struct lapd_datalink *dl = lctx->dl; - struct msgb *msg = dp->oph.msg; - - msgb_free(msg); - - /* send notification to L3 */ - return send_dl_simple(PRIM_DL_REL, PRIM_OP_CONFIRM, &dl->lctx); -} - -/* statefull handling for DL SAP messages from L3 */ -static struct l2downstate { - uint32_t states; - int prim, op; - const char *name; - int (*rout) (struct osmo_dlsap_prim *dp, - struct lapd_msg_ctx *lctx); -} l2downstatelist[] = { - /* create and send UI command */ - {ALL_STATES, - PRIM_DL_UNIT_DATA, PRIM_OP_REQUEST, - "DL-UNIT-DATA-REQUEST", lapd_udata_req}, - - /* create and send SABM command */ - {SBIT(LAPD_STATE_IDLE), - PRIM_DL_EST, PRIM_OP_REQUEST, - "DL-ESTABLISH-REQUEST", lapd_est_req}, - - /* create and send I command */ - {SBIT(LAPD_STATE_MF_EST) | - SBIT(LAPD_STATE_TIMER_RECOV), - PRIM_DL_DATA, PRIM_OP_REQUEST, - "DL-DATA-REQUEST", lapd_data_req}, - - /* suspend datalink */ - {SBIT(LAPD_STATE_MF_EST) | - SBIT(LAPD_STATE_TIMER_RECOV), - PRIM_DL_SUSP, PRIM_OP_REQUEST, - "DL-SUSPEND-REQUEST", lapd_susp_req}, - - /* create and send SABM command (resume) */ - {SBIT(LAPD_STATE_MF_EST) | - SBIT(LAPD_STATE_TIMER_RECOV), - PRIM_DL_RES, PRIM_OP_REQUEST, - "DL-RESUME-REQUEST", lapd_res_req}, - - /* create and send SABM command (reconnect) */ - {SBIT(LAPD_STATE_IDLE) | - SBIT(LAPD_STATE_MF_EST) | - SBIT(LAPD_STATE_TIMER_RECOV), - PRIM_DL_RECON, PRIM_OP_REQUEST, - "DL-RECONNECT-REQUEST", lapd_res_req}, - - /* create and send DISC command */ - {SBIT(LAPD_STATE_SABM_SENT) | - SBIT(LAPD_STATE_MF_EST) | - SBIT(LAPD_STATE_TIMER_RECOV) | - SBIT(LAPD_STATE_DISC_SENT), - PRIM_DL_REL, PRIM_OP_REQUEST, - "DL-RELEASE-REQUEST", lapd_rel_req}, - - /* release in idle state */ - {SBIT(LAPD_STATE_IDLE), - PRIM_DL_REL, PRIM_OP_REQUEST, - "DL-RELEASE-REQUEST", lapd_rel_req_idle}, -}; - -#define L2DOWNSLLEN \ - (sizeof(l2downstatelist) / sizeof(struct l2downstate)) - -int lapd_recv_dlsap(struct osmo_dlsap_prim *dp, struct lapd_msg_ctx *lctx) -{ - struct lapd_datalink *dl = lctx->dl; - int i, supported = 0; - struct msgb *msg = dp->oph.msg; - int rc; - - /* find function for current state and message */ - for (i = 0; i < L2DOWNSLLEN; i++) { - if (dp->oph.primitive == l2downstatelist[i].prim - && dp->oph.operation == l2downstatelist[i].op) { - supported = 1; - if ((SBIT(dl->state) & l2downstatelist[i].states)) - break; - } - } - if (!supported) { - LOGP(DLLAPD, LOGL_NOTICE, "Message %u/%u unsupported.\n", - dp->oph.primitive, dp->oph.operation); - msgb_free(msg); - return 0; - } - if (i == L2DOWNSLLEN) { - LOGP(DLLAPD, LOGL_NOTICE, "Message %u/%u unhandled at this " - "state %s.\n", dp->oph.primitive, dp->oph.operation, - lapd_state_names[dl->state]); - msgb_free(msg); - return 0; - } - - LOGP(DLLAPD, LOGL_INFO, "Message %s received in state %s\n", - l2downstatelist[i].name, lapd_state_names[dl->state]); - - rc = l2downstatelist[i].rout(dp, lctx); - - return rc; -} - |