diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/gsm/Makefile.am | 2 | ||||
| -rw-r--r-- | src/gsm/lapd_core.c | 2128 | ||||
| -rw-r--r-- | src/gsm/lapdm.c | 1947 |
3 files changed, 2456 insertions, 1621 deletions
diff --git a/src/gsm/Makefile.am b/src/gsm/Makefile.am index f5e46769..c0f72b3f 100644 --- a/src/gsm/Makefile.am +++ b/src/gsm/Makefile.am @@ -10,6 +10,6 @@ lib_LTLIBRARIES = libosmogsm.la libosmogsm_la_SOURCES = a5.c rxlev_stat.c tlv_parser.c comp128.c gsm_utils.c \ rsl.c gsm48.c gsm48_ie.c gsm0808.c sysinfo.c \ gprs_cipher_core.c gsm0480.c abis_nm.c gsm0502.c \ - lapdm.c + lapd_core.c lapdm.c libosmogsm_la_LDFLAGS = -version-info $(LIBVERSION) libosmogsm_la_LIBADD = $(top_builddir)/src/libosmocore.la diff --git a/src/gsm/lapd_core.c b/src/gsm/lapd_core.c new file mode 100644 index 00000000..f7408e54 --- /dev/null +++ b/src/gsm/lapd_core.c @@ -0,0 +1,2128 @@ +/* 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! " |