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diff --git a/src/gsm/lapd_core.c b/src/gsm/lapd_core.c
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+/* 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
+
+/* 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_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 */
+ if (osmo_timer_pending(&dl->t203)) {
+ LOGP(DLLAPD, LOGL_INFO, "stop T203\n");
+ osmo_timer_del(&dl->t203);
+ }
+ /* 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) {
+ LOGP(DLLAPD, LOGL_INFO, "start T203\n");
+ osmo_timer_schedule(&dl->t203, dl->t203_sec, dl->t203_usec);
+ }
+
+ dl->state = state;
+}
+
+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);
+
+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;
+ }
+ /* reset Timers */
+ osmo_timer_del(&dl->t200);
+ osmo_timer_del(&dl->t203);
+}
+
+/* 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, "lapd_t200_cb(%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) */
+ osmo_timer_schedule(&dl->t200, dl->t200_sec, dl->t200_usec);
+ 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) */
+ osmo_timer_schedule(&dl->t200, dl->t200_sec, dl->t200_usec);
+ 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) */
+ osmo_timer_schedule(&dl->t200, dl->t200_sec,
+ dl->t200_usec);
+ } 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, "lapd_t203_cb(%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 */
+ osmo_timer_schedule(&dl->t200, dl->t200_sec, dl->t200_usec);
+}
+
+/* 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, t200_start = 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)) {
+ LOGP(DLLAPD, 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_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 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_hist[sub_mod(dl->v_send, 1, dl->range_hist)].msg) {
+ LOGP(DLLAPD, LOGL_INFO, "start T200, due to unacked I "
+ "frame(s)\n");
+ t200_start = 1;
+ osmo_timer_schedule(&dl->t200, dl->t200_sec,
+ dl->t200_usec);
+ }
+ }
+
+ /* This also does a restart, when I or S frame is received */
+
+ /* Stop T203, if running */
+ if (osmo_timer_pending(&dl->t203)) {
+ osmo_timer_del(&dl->t203);
+ LOGP(DLLAPD, LOGL_INFO, "stop T203\n");
+ }
+ /* 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)) {
+ LOGP(DLLAPD, LOGL_INFO, "start T203\n");
+ osmo_timer_schedule(&dl->t203, dl->t203_sec, dl->t203_usec);
+ }
+}
+
+/* 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;
+ 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);
+ /* reset Timer T200 */
+ osmo_timer_del(&dl->t200);
+ 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:
+ /* reset Timer T200 */
+ osmo_timer_del(&dl->t200);
+ /* 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;
+ }
+ /* reset T200 */
+ osmo_timer_del(&dl->t200);
+ /* 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);
+ /* reset Timer T200 */
+ osmo_timer_del(&dl->t200);
+ /* 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);
+ /* reset Timer T200 */
+ osmo_timer_del(&dl->t200);
+ /* 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");
+ /* reset Timer T200 */
+ osmo_timer_del(&dl->t200);
+ /* 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");
+ /* reset Timer T200 */
+ osmo_timer_del(&dl->t200);
+ /* 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;
+ /* reset Timer T200 */
+ osmo_timer_del(&dl->t200);
+ /* 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;
+ /* reset Timer T200 */
+ osmo_timer_del(&dl->t200);
+ /* 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;
+ /* reset Timer T200 */
+ osmo_timer_del(&dl->t200);
+ /* 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) {
+ /* FIXME: help me understand what exactly todo here
+ dl->seq_err_cond = 1;
+ */
+ lapd_send_rej(lctx, lctx->p_f);
+ } else {
+ }
+ return -EIO;
+ }
+ 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);
+ osmo_timer_schedule(&dl->t200, dl->t200_sec, dl->t200_usec);
+
+ 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;
+
+ LOGP(DLLAPD, LOGL_INFO, "writing message to send-queue\n");
+
+ /* 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)) {
+ osmo_timer_schedule(&dl->t200, dl->t200_sec, dl->t200_usec);
+ /* reset Timer T203, if running */
+ if (osmo_timer_pending(&dl->t203)) {
+ LOGP(DLLAPD, LOGL_INFO, "stop T203\n");
+ osmo_timer_del(&dl->t203);
+ }
+ }
+
+ 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 */
+ if (osmo_timer_pending(&dl->t203)) {
+ LOGP(DLLAPD, LOGL_INFO, "stop T203\n");
+ osmo_timer_del(&dl->t203);
+ }
+ osmo_timer_del(&dl->t200);
+
+ 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;
+ }
+
+ /* 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);
+ osmo_timer_schedule(&dl->t200, dl->t200_sec, dl->t200_usec);
+
+ 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);
+ /* reset Timer T200 */
+ osmo_timer_del(&dl->t200);
+ /* enter idle state */
+ 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);
+ osmo_timer_schedule(&dl->t200, dl->t200_sec, dl->t200_usec);
+
+ 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;
+}
+
generated by cgit v1.2.3 (git 2.25.1) at 2024-04-24 08:41:44 +0000