diff options
| -rw-r--r-- | include/osmocom/gsm/Makefile.am | 2 | ||||
| -rw-r--r-- | include/osmocom/gsm/lapd_core.h | 171 | ||||
| -rw-r--r-- | include/osmocom/gsm/lapdm.h | 51 | ||||
| -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 |
6 files changed, 2631 insertions, 1670 deletions
diff --git a/include/osmocom/gsm/Makefile.am b/include/osmocom/gsm/Makefile.am index 90f19bc5..5971d0c5 100644 --- a/include/osmocom/gsm/Makefile.am +++ b/include/osmocom/gsm/Makefile.am @@ -1,6 +1,6 @@ osmogsm_HEADERS = a5.h comp128.h gsm0808.h gsm48_ie.h mncc.h rxlev_stat.h \ gsm0480.h gsm48.h gsm_utils.h rsl.h tlv.h abis_nm.h \ - sysinfo.h prim.h gsm0502.h lapdm.h + sysinfo.h prim.h gsm0502.h lapd_core.h lapdm.h SUBDIRS = protocol diff --git a/include/osmocom/gsm/lapd_core.h b/include/osmocom/gsm/lapd_core.h new file mode 100644 index 00000000..0f4e8899 --- /dev/null +++ b/include/osmocom/gsm/lapd_core.h @@ -0,0 +1,171 @@ +#ifndef _OSMOCOM_LAPD_H +#define _OSMOCOM_LAPD_H + +#include <stdint.h> + +#include <osmocom/core/timer.h> +#include <osmocom/core/msgb.h> +#include <osmocom/gsm/prim.h> + +/*! \defgroup lapd LAPD implementation common part + * @{ + */ + +/*! \file lapd.h */ + +/* primitive related sutff */ + +/*! \brief LAPD related primitives (L2<->L3 SAP)*/ +enum osmo_dl_prim { + PRIM_DL_UNIT_DATA, /*!< \brief DL-UNIT-DATA */ + PRIM_DL_DATA, /*!< \brief DL-DATA */ + PRIM_DL_EST, /*!< \brief DL-ESTABLISH */ + PRIM_DL_REL, /*!< \brief DL-RLEEASE */ + PRIM_DL_SUSP, /*!< \brief DL-SUSPEND */ + PRIM_DL_RES, /*!< \brief DL-RESUME */ + PRIM_DL_RECON, /*!< \brief DL-RECONNECT */ + PRIM_MDL_ERROR, /*!< \brief MDL-ERROR */ +}; + +/* Uses the same values as RLL, so no conversion for GSM is required. */ +#define MDL_CAUSE_T200_EXPIRED 0x01 +#define MDL_CAUSE_REEST_REQ 0x02 +#define MDL_CAUSE_UNSOL_UA_RESP 0x03 +#define MDL_CAUSE_UNSOL_DM_RESP 0x04 +#define MDL_CAUSE_UNSOL_DM_RESP_MF 0x05 +#define MDL_CAUSE_UNSOL_SPRV_RESP 0x06 +#define MDL_CAUSE_SEQ_ERR 0x07 +#define MDL_CAUSE_UFRM_INC_PARAM 0x08 +#define MDL_CAUSE_SFRM_INC_PARAM 0x09 +#define MDL_CAUSE_IFRM_INC_MBITS 0x0a +#define MDL_CAUSE_IFRM_INC_LEN 0x0b +#define MDL_CAUSE_FRM_UNIMPL 0x0c +#define MDL_CAUSE_SABM_MF 0x0d +#define MDL_CAUSE_SABM_INFO_NOTALL 0x0e +#define MDL_CAUSE_FRMR 0x0f + +/*! \brief for MDL-ERROR.ind */ +struct mdl_error_ind_param { + uint8_t cause; /*!< \brief generic cause value */ +}; + +/*! \brief for DL-REL.req */ +struct dl_rel_req_param { + uint8_t mode; /*!< \brief release mode */ +}; + +/*! \brief primitive header for LAPD DL-SAP primitives */ +struct osmo_dlsap_prim { + struct osmo_prim_hdr oph; /*!< \brief generic primitive header */ + union { + struct mdl_error_ind_param error_ind; + struct dl_rel_req_param rel_req; + } u; /*!< \brief request-specific data */ +}; + +/*! \brief LAPD mode/role */ +enum lapd_mode { + LAPD_MODE_USER, /*!< \brief behave like user */ + LAPD_MODE_NETWORK, /*!< \brief behave like network */ +}; + +/*! \brief LAPD state (Figure B.2/Q.921)*/ +enum lapd_state { + LAPD_STATE_NULL = 0, + 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, +}; + +/*! \brief LAPD message format (I / S / U) */ +enum lapd_format { + LAPD_FORM_UKN = 0, + LAPD_FORM_I, + LAPD_FORM_S, + LAPD_FORM_U, +}; + +/*! \brief LAPD message context */ +struct lapd_msg_ctx { + struct lapd_datalink *dl; + int n201; + /* address */ + uint8_t cr; + uint8_t sapi; + uint8_t tei; + uint8_t lpd; + /* control */ + uint8_t format; + uint8_t p_f; /* poll / final bit */ + uint8_t n_send; + uint8_t n_recv; + uint8_t s_u; /* S or repectivly U function bits */ + /* length */ + int length; + uint8_t more; +}; + +struct lapd_cr_ent { + uint8_t cmd; + uint8_t resp; +}; + +struct lapd_history { + struct msgb *msg; /* message to be sent / NULL, if histoy is empty */ + int more; /* if message is fragmented */ +}; + +/*! \brief LAPD datalink */ +struct lapd_datalink { + int (*send_dlsap)(struct osmo_dlsap_prim *dp, + struct lapd_msg_ctx *lctx); + int (*send_ph_data_req)(struct lapd_msg_ctx *lctx, struct msgb *msg); + struct { + /*! \brief filled-in once we set the lapd_mode above */ + struct lapd_cr_ent loc2rem; + struct lapd_cr_ent rem2loc; + } cr; + enum lapd_mode mode; /*!< \brief current mode of link */ + int use_sabme; /*!< \brief use SABME instead of SABM */ + int reestablish; /*!< \brief enable reestablish support */ + int n200, n200_est_rel; /*!< \brief number of retranmissions */ + struct lapd_msg_ctx lctx; /*!< \brief LAPD context */ + int maxf; /*!< \brief maximum frame size (after defragmentation) */ + uint8_t k; /*!< \brief maximum number of unacknowledged frames */ + uint8_t v_range; /*!< \brief range of sequence numbers */ + uint8_t v_send; /*!< \brief seq nr of next I frame to be transmitted */ + uint8_t v_ack; /*!< \brief last frame ACKed by peer */ + uint8_t v_recv; /*!< \brief seq nr of next I frame expected to be received */ + uint32_t state; /*!< \brief LAPD state (\ref lapd_state) */ + int seq_err_cond; /*!< \brief condition of sequence error */ + uint8_t own_busy; /*!< \brief receiver busy on our side */ + uint8_t peer_busy; /*!< \brief receiver busy on remote side */ + int t200_sec, t200_usec; /*!< \brief retry timer (default 1 sec) */ + int t203_sec, t203_usec; /*!< \brief retry timer (default 10 secs) */ + struct osmo_timer_list t200; /*!< \brief T200 timer */ + struct osmo_timer_list t203; /*!< \brief T203 timer */ + uint8_t retrans_ctr; /*!< \brief re-transmission counter */ + struct llist_head tx_queue; /*!< \brief frames to L1 */ + struct llist_head send_queue; /*!< \brief frames from L3 */ + struct msgb *send_buffer; /*!< \brief current frame transmitting */ + int send_out; /*!< \brief how much was sent from send_buffer */ + struct lapd_history *tx_hist; /*!< \brief tx history structure array */ + uint8_t range_hist; /*!< \brief range of history buffer 2..2^n */ + struct msgb *rcv_buffer; /*!< \brief buffer to assemble the received message */ + struct msgb *cont_res; /*!< \brief buffer to store content resolution data on network side, to detect multiple phones on same channel */ +}; + +void lapd_dl_init(struct lapd_datalink *dl, uint8_t k, uint8_t v_range, + int maxf); +void lapd_dl_exit(struct lapd_datalink *dl); +void lapd_dl_reset(struct lapd_datalink *dl); +int lapd_set_mode(struct lapd_datalink *dl, enum lapd_mode mode); +int lapd_ph_data_ind(struct msgb *msg, struct lapd_msg_ctx *lctx); +int lapd_recv_dlsap(struct osmo_dlsap_prim *dp, struct lapd_msg_ctx *lctx); + +#endif /* _OSMOCOM_LAPD_H */ diff --git a/include/osmocom/gsm/lapdm.h b/include/osmocom/gsm/lapdm.h index b71feef1..cc9c63fe 100644 --- a/include/osmocom/gsm/lapdm.h +++ b/include/osmocom/gsm/lapdm.h @@ -1,11 +1,7 @@ #ifndef _OSMOCOM_LAPDM_H #define _OSMOCOM_LAPDM_H -#include <stdint.h> - -#include <osmocom/core/timer.h> -#include <osmocom/core/msgb.h> -#include <osmocom/gsm/prim.h> +#include <osmocom/gsm/lapd_core.h> /*! \defgroup lapdm LAPDm implementation according to GSM TS 04.06 * @{ @@ -15,7 +11,7 @@ /* primitive related sutff */ -/*! \brief LAPDm related primitives */ +/*! \brief LAPDm related primitives (L1<->L2 SAP) */ enum osmo_ph_prim { PRIM_PH_DATA, /*!< \brief PH-DATA */ PRIM_PH_RACH, /*!< \brief PH-RANDOM_ACCESS */ @@ -68,52 +64,22 @@ enum lapdm_mode { LAPDM_MODE_BTS, /*!< \brief behave like a BTS (network) */ }; -/*! \brief LAPDm state */ -enum lapdm_state { - LAPDm_STATE_NULL = 0, - LAPDm_STATE_IDLE, - LAPDm_STATE_SABM_SENT, - LAPDm_STATE_MF_EST, - LAPDm_STATE_TIMER_RECOV, - LAPDm_STATE_DISC_SENT, -}; - struct lapdm_entity; /*! \brief LAPDm message context */ struct lapdm_msg_ctx { struct lapdm_datalink *dl; int lapdm_fmt; - uint8_t n201; uint8_t chan_nr; uint8_t link_id; - uint8_t addr; - uint8_t ctrl; uint8_t ta_ind; uint8_t tx_power_ind; }; /*! \brief LAPDm datalink like TS 04.06 / Section 3.5.2 */ struct lapdm_datalink { - uint8_t V_send; /*!< \brief seq nr of next I frame to be transmitted */ - uint8_t V_ack; /*!< \brief last frame ACKed by peer */ - uint8_t N_send; /*!< \brief ? set to V_send at Tx time*/ - uint8_t V_recv; /*!< \brief seq nr of next I frame expected to be received */ - uint8_t N_recv; /*!< \brief expected send seq nr of the next received I frame */ - uint32_t state; /*!< \brief LAPDm state (\ref lapdm_state) */ - int seq_err_cond; /*!< \brief condition of sequence error */ - uint8_t own_busy; /*!< \brief receiver busy on our side */ - uint8_t peer_busy; /*!< \brief receiver busy on remote side */ - struct osmo_timer_list t200; /*!< \brief T200 timer */ - uint8_t retrans_ctr; /*!< \brief re-transmission counter */ - struct llist_head send_queue; /*!< \brief frames from L3 */ - struct msgb *send_buffer; /*!< \brief current frame transmitting */ - int send_out; /*!< \brief how much was sent from send_buffer */ - uint8_t tx_hist[8][200]; /*!< \brief tx history buffer */ - int tx_length[8]; /*!< \brief length in history buffer */ - struct llist_head tx_queue; /*!< \brief frames to L1 */ + struct lapd_datalink dl; /* \brief common LAPD */ struct lapdm_msg_ctx mctx; /*!< \brief context of established connection */ - struct msgb *rcv_buffer; /*!< \brief buffer to assemble the received message */ struct lapdm_entity *entity; /*!< \brief LAPDm entity we are part of */ }; @@ -127,11 +93,6 @@ enum lapdm_dl_sapi { typedef int (*lapdm_cb_t)(struct msgb *msg, struct lapdm_entity *le, void *ctx); -struct lapdm_cr_ent { - uint8_t cmd; - uint8_t resp; -}; - #define LAPDM_ENT_F_EMPTY_FRAME 0x0001 #define LAPDM_ENT_F_POLLING_ONLY 0x0002 @@ -144,12 +105,6 @@ struct lapdm_entity { enum lapdm_mode mode; /*!< \brief are we in BTS mode or MS mode */ unsigned int flags; - struct { - /*! \brief filled-in once we set the lapdm_mode above */ - struct lapdm_cr_ent loc2rem; - struct lapdm_cr_ent rem2loc; - } cr; - void *l1_ctx; /*!< \brief context for layer1 instance */ void *l3_ctx; /*!< \brief context for layer3 instance */ 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 |