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osmocom-bb/src/host/layer23/src/lapdm.c

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/* GSM LAPDm (TS 04.06) implementation */
/* (C) 2010 by Harald Welte <laforge@gnumonks.org>
*
* 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.
*
*/
#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <errno.h>
#include <osmocore/logging.h>
#include <osmocore/timer.h>
#include <osmocore/msgb.h>
#include <osmocore/tlv.h>
#include <osmocore/utils.h>
#include <osmocore/rsl.h>
#include <osmocore/protocol/gsm_04_08.h>
#include <osmocore/protocol/gsm_08_58.h>
#include <osmocom/osmocom_data.h>
#include <osmocom/l1ctl.h>
#include <osmocom/lapdm.h>
#include <osmocom/logging.h>
#include <l1a_l23_interface.h>
/* TS 04.06 Figure 4 / Section 3.2 */
#define LAPDm_LPD_NORMAL 0
#define LAPDm_LPD_SMSCB 1
#define LAPDm_SAPI_NORMAL 0
#define LAPDm_SAPI_SMS 3
#define LAPDm_ADDR(lpd, sapi, cr) (((lpd & 0x3) << 5) | ((sapi & 0x7) << 2) | ((cr & 0x1) << 1) | 0x1)
#define LAPDm_ADDR_SAPI(addr) ((addr >> 2) & 0x7)
/* TS 04.06 Table 3 / Section 3.4.3 */
#define LAPDm_CTRL_I(nr, ns, p) (((nr & 0x7) << 5) | ((p & 0x1) << 4) | ((ns & 0x7) << 1))
#define LAPDm_CTRL_S(nr, s, p) (((nr & 0x7) << 5) | ((p & 0x1) << 4) | ((s & 0x3) << 2) | 0x1)
#define LAPDm_CTRL_U(u, p) (((u & 0x1c) << (5-2)) | ((p & 0x1) << 4) | ((u & 0x3) << 2) | 0x3)
#define LAPDm_CTRL_is_I(ctrl) ((ctrl & 0x1) == 0)
#define LAPDm_CTRL_is_S(ctrl) ((ctrl & 0x3) == 1)
#define LAPDm_CTRL_is_U(ctrl) ((ctrl & 0x3) == 3)
#define LAPDm_CTRL_U_BITS(ctrl) (((ctrl & 0xC) >> 2) | (ctrl & 0xE0) >> 3)
#define LAPDm_CTRL_PF_BIT(ctrl) ((ctrl >> 4) & 0x1)
#define LAPDm_CTRL_S_BITS(ctrl) ((ctrl & 0xC) >> 2)
#define LAPDm_CTRL_I_Ns(ctrl) ((ctrl & 0xE) >> 1)
#define LAPDm_CTRL_I_Nr(ctrl) ((ctrl & 0xE0) >> 5)
/* TS 04.06 Table 4 / Section 3.8.1 */
#define LAPDm_U_SABM 0x7
#define LAPDm_U_DM 0x3
#define LAPDm_U_UI 0x0
#define LAPDm_U_DISC 0x8
#define LAPDm_U_UA 0xC
#define LAPDm_S_RR 0x0
#define LAPDm_S_RNR 0x1
#define LAPDm_S_REJ 0x2
#define LAPDm_LEN(len) ((len << 2) | 0x1)
/* TS 04.06 Section 5.8.3 */
#define N201_AB_SACCH 18
#define N201_AB_SDCCH 20
#define N201_AB_FACCH 20
#define N201_Bbis 23
#define N201_Bter_SACCH 21
#define N201_Bter_SDCCH 23
#define N201_Bter_FACCH 23
#define N201_B4 19
/* 5.8.2.1 N200 during establish and release */
#define N200_EST_REL 5
/* 5.8.2.1 N200 during timer recovery state */
#define N200_TR_SACCH 5
#define N200_TR_SDCCH 23
#define N200_TR_FACCH_FR 34
#define N200_TR_EFACCH_FR 48
#define N200_TR_FACCH_HR 29
/* FIXME: this depends on chan type */
#define N200 N200_TR_SACCH
#define CR_MS2BS_CMD 0
#define CR_MS2BS_RESP 1
#define CR_BS2MS_CMD 1
#define CR_BS2MS_RESP 0
/* Set T200 to 1 Second (OpenBTS uses 900ms) */
#define T200 1, 0
enum lapdm_format {
LAPDm_FMT_A,
LAPDm_FMT_B,
LAPDm_FMT_Bbis,
LAPDm_FMT_Bter,
LAPDm_FMT_B4,
};
struct lapdm_msg_ctx {
struct lapdm_datalink *dl;
enum lapdm_format lapdm_fmt;
uint8_t chan_nr;
uint8_t link_id;
uint8_t addr;
uint8_t ctrl;
};
static void lapdm_t200_cb(void *data);
/* UTILITY FUNCTIONS */
static inline uint8_t inc_mod8(uint8_t x)
{
return (x + 1) % 8;
}
static void lapdm_dl_init(struct lapdm_datalink *dl,
struct lapdm_entity *entity)
{
memset(dl, 0, sizeof(*dl));
dl->t200.data = dl;
dl->t200.cb = &lapdm_t200_cb;
dl->entity = entity;
}
void lapdm_init(struct lapdm_entity *le, struct osmocom_ms *ms)
{
unsigned int i;
for (i = 0; i < ARRAY_SIZE(le->datalink); i++)
lapdm_dl_init(&le->datalink[i], le);
le->ms = ms;
}
static struct lapdm_datalink *datalink_for_sapi(struct lapdm_entity *le, uint8_t sapi)
{
switch (sapi) {
case LAPDm_SAPI_NORMAL:
return &le->datalink[0];
case LAPDm_SAPI_SMS:
return &le->datalink[1];
default:
return NULL;
}
}
/* remove the L2 header from a MSGB */
static inline unsigned char *msgb_pull_l2h(struct msgb *msg)
{
unsigned char *ret = msgb_pull(msg, msg->l3h - msg->l2h);
msg->l2h = NULL;
return ret;
}
/* Append padding (if required) */
static void lapdm_pad_msgb(struct msgb *msg)
{
int pad_len = 23 - msgb_l2len(msg);
uint8_t *data;
if (pad_len < 0) {
LOGP(DLAPDM, LOGL_ERROR,
"cannot pad message that is already too big!\n");
return;
}
data = msgb_put(msg, pad_len);
memset(data, 0x2B, pad_len);
}
static int tx_ph_data_req_pad(struct osmocom_ms *ms, struct msgb *msg,
uint8_t chan_nr, uint8_t link_id)
{
lapdm_pad_msgb(msg);
return tx_ph_data_req(ms, msg, chan_nr, link_id);
}
/* Take a Bbis format message from L1 and create RSLms UNIT DATA IND */
static int send_rslms_rll_l3(uint8_t msg_type, struct lapdm_msg_ctx *mctx,
struct msgb *msg)
{
/* Add the RSL + RLL header */
rsl_rll_push_l3(msg, msg_type, mctx->chan_nr, mctx->link_id, 1);
/* send off the RSLms message to L3 */
return rslms_sendmsg(msg, mctx->dl->entity->ms);
}
static int send_rslms_rll_simple(uint8_t msg_type, struct lapdm_msg_ctx *mctx)
{
struct msgb *msg;
msg = rsl_rll_simple(msg_type, mctx->chan_nr, mctx->link_id, 1);
/* send off the RSLms message to L3 */
return rslms_sendmsg(msg, mctx->dl->entity->ms);
}
static int check_length_ind(uint8_t length_ind)
{
if (!(length_ind & 0x01)) {
/* G.4.1 If the EL bit is set to "0", an MDL-ERROR-INDICATION
* primitive with cause "frame not implemented" is sent to the
* mobile management entity. */
LOGP(DLAPDM, LOGL_ERROR,
"we don't support multi-octet length\n");
return -EINVAL;
}
if (length_ind & 0x02) {
LOGP(DLAPDM, LOGL_ERROR,
"we don't support LAPDm fragmentation yet\n");
return -EINVAL;
}
return 0;
}
/* Timer callback on T200 expiry */
static void lapdm_t200_cb(void *data)
{
struct lapdm_datalink *dl = data;
DEBUGP(DLAPDM, "lapdm_t200_cb(%p) state=%u\n", dl, dl->state);
switch (dl->state) {
case LAPDm_STATE_SABM_SENT:
/* 5.4.1.3 */
if (dl->retrans_ctr >= N200_EST_REL + 1) {
/* FIXME: send RELEASE INDICATION to L3 */
dl->retrans_ctr = 0;
dl->state = LAPDm_STATE_IDLE;
}
/* FIXME: retransmit SABM command */
//rslms_rx_rll_est_req(msg, dl);
/* increment re-transmission counter */
dl->retrans_ctr++;
/* restart T200 (PH-READY-TO-SEND) */
bsc_schedule_timer(&dl->t200, T200);
break;
case LAPDm_STATE_MF_EST:
/* 5.5.7 */
dl->retrans_ctr = 0;
dl->state = LAPDm_STATE_TIMER_RECOV;
case LAPDm_STATE_TIMER_RECOV:
dl->retrans_ctr++;
if (dl->retrans_ctr < N200) {
/* FIXME: retransmit I frame (V_s-1) with P=1 */
/* FIXME: send appropriate supervision frame with P=1 */
/* restart T200 (PH-READY-TO-SEND) */
bsc_schedule_timer(&dl->t200, T200);
} else {
/* FIXME: send ERROR INDICATION to L3 */
}
break;
default:
DEBUGP(DLAPDM, "T200 expired in unexpected dl->state %u\n",
dl->state);
}
}
static int lapdm_send_rr(struct lapdm_msg_ctx *mctx, uint8_t f_bit)
{
uint8_t sapi = mctx->link_id & 7;
struct msgb *msg = msgb_alloc_headroom(23+10, 10, "LAPDm RR");
msg->l2h = msgb_put(msg, 3);
msg->l2h[0] = LAPDm_ADDR(LAPDm_LPD_NORMAL, sapi, CR_MS2BS_RESP);
msg->l2h[1] = LAPDm_CTRL_S(mctx->dl->V_recv, LAPDm_S_RR, f_bit);
msg->l2h[2] = LAPDm_LEN(0);
return tx_ph_data_req_pad(mctx->dl->entity->ms, msg, mctx->chan_nr, mctx->link_id);
}
/* L1 -> L2 */
/* Receive a LAPDm S (Unnumbered) message from L1 */
static int lapdm_rx_u(struct msgb *msg, struct lapdm_msg_ctx *mctx)
{
struct lapdm_datalink *dl = mctx->dl;
uint8_t length;
int rc;
switch (LAPDm_CTRL_U_BITS(mctx->ctrl)) {
case LAPDm_U_SABM:
DEBUGPC(DLAPDM, "SABM ");
/* Must be Format B */
rc = check_length_ind(msg->l2h[2]);
if (rc < 0)
return rc;
length = msg->l2h[2] >> 2;
/* FIXME: G.4.5 check */
if (dl->state == LAPDm_STATE_MF_EST) {
if (length == 0) {
/* FIXME: re-establishment procedure 5.6 */
} else {
/* FIXME: check for contention resoultion */
DEBUGP(DLAPDM, "SABM command, multiple "
"frame established state\n");
return 0;
}
}
if (length == 0) {
/* 5.4.1.2 Normal establishment procedures */
rc = send_rslms_rll_simple(RSL_MT_EST_IND, mctx);
} else {
/* 5.4.1.4 Contention resolution establishment */
msg->l3h = msg->l2h + 3;
msgb_pull_l2h(msg);
rc = send_rslms_rll_l3(RSL_MT_EST_IND, mctx, msg);
}
#if 0
if (rc == 0)
dl->state = LAPDm_STATE_SABM_SENT;
#endif
break;
case LAPDm_U_DM:
DEBUGPC(DLAPDM, "DM ");
if (!LAPDm_CTRL_PF_BIT(mctx->ctrl)) {
/* 5.4.1.2 DM responses with the F bit set to "0" shall be ignored. */
return 0;
}
switch (dl->state) {
case LAPDm_STATE_IDLE:
/* 5.4.5 all other frame types shall be discarded */
DEBUGPC(DLAPDM, "state=IDLE (discarding) ");
return 0;
case LAPDm_STATE_MF_EST:
if (LAPDm_CTRL_PF_BIT(mctx->ctrl) == 1)
DEBUGPC(DLAPDM, "unsolicited DM resposne ");
else
DEBUGPC(DLAPDM, "unsolicited DM resposne, multiple frame established state ");
return 0;
case LAPDm_STATE_TIMER_RECOV:
/* DM is normal in case PF = 1 */
if (LAPDm_CTRL_PF_BIT(mctx->ctrl) == 0) {
DEBUGPC(DLAPDM, "unsolicited DM resposne, multiple frame established state ");
return 0;
}
break;
}
/* reset T200 */
bsc_del_timer(&dl->t200);
rc = send_rslms_rll_simple(RSL_MT_REL_IND, mctx);
break;
case LAPDm_U_UI:
DEBUGP(DLAPDM, "UI ");
if (mctx->lapdm_fmt == LAPDm_FMT_B4) {
length = N201_B4;
msg->l3h = msg->l2h + 2;
} else {
rc = check_length_ind(msg->l2h[2]);
if (rc < 0)
return rc;
length = msg->l2h[2] >> 2;
msg->l3h = msg->l2h + 3;
}
/* do some length checks */
if (length == 0) {
/* 5.3.3 UI frames received with the length indicator set to "0" shall be ignored */
DEBUGP(DLAPDM, "length=0 (discarding) ");
return 0;
}
/* FIXME: G.4.5 check */
switch (LAPDm_ADDR_SAPI(mctx->ctrl)) {
case LAPDm_SAPI_NORMAL:
case LAPDm_SAPI_SMS:
break;
default:
/* 5.3.3 UI frames with invalid SAPI values shall be discarded */
DEBUGP(DLAPDM, "sapi=%u (discarding) ", LAPDm_ADDR_SAPI(mctx->ctrl));
return 0;
}
msgb_pull_l2h(msg);
rc = send_rslms_rll_l3(RSL_MT_UNIT_DATA_IND, mctx, msg);
break;
case LAPDm_U_DISC:
DEBUGP(DLAPDM, "DISC ");
length = msg->l2h[2] >> 2;
if (length > 0 || msg->l2h[2] & 0x02) {
/* G.4.4 If a DISC or DM frame is received with L>0 or
* with the M bit set to "1", an MDL-ERROR-INDICATION
* primitive with cause "U frame with incorrect
* parameters" is sent to the mobile management entity. */
LOGP(DLAPDM, LOGL_ERROR,
"U frame iwth incorrect parameters ");
return -EIO;
}
switch (dl->state) {
case LAPDm_STATE_IDLE:
/* FIXME: send DM with F=P */
break;
default:
/* FIXME */
break;
}
break;
case LAPDm_U_UA:
DEBUGP(DLAPDM, "UA ");
/* FIXME: G.4.5 check */
if (!LAPDm_CTRL_PF_BIT(mctx->ctrl)) {
/* 5.4.1.2 A UA response with the F bit set to "0" shall be ignored. */
DEBUGP(DLAPDM, "F=0 (discarding) ");
return 0;
}
switch (dl->state) {
case LAPDm_STATE_SABM_SENT:
break;
case LAPDm_STATE_IDLE:
/* 5.4.5 all other frame types shall be discarded */
default:
DEBUGP(DLAPDM,
"unsolicited UA response! (discarding) ");
return 0;
}
/* reset Timer T200 */
bsc_del_timer(&dl->t200);
/* set Vs, Vr and Va to 0 */
dl->V_send = dl->V_recv = dl->V_ack = 0;
/* enter multiple-frame-established state */
dl->state = LAPDm_STATE_MF_EST;
/* send notification to L3 */
rc = send_rslms_rll_simple(RSL_MT_EST_CONF, mctx);
break;
}
return rc;
}
/* Receive a LAPDm S (Supervisory) message from L1 */
static int lapdm_rx_s(struct msgb *msg, struct lapdm_msg_ctx *mctx)
{
struct lapdm_datalink *dl = mctx->dl;
uint8_t length;
length = msg->l2h[2] >> 2;
if (length > 0 || msg->l2h[2] & 0x02) {
/* G.4.3 If a supervisory frame is received with L>0 or
* with the M bit set to "1", an MDL-ERROR-INDICATION
* primitive with cause "S frame with incorrect
* parameters" is sent to the mobile management entity. */
return -EIO;
}
switch (dl->state) {
case LAPDm_STATE_IDLE:
/* FIXME: if P=1, respond DM with F=1 (5.2.2) */
/* 5.4.5 all other frame types shall be discarded */
break;
}
switch (LAPDm_CTRL_S_BITS(mctx->ctrl)) {
case LAPDm_S_RR:
/* FIXME */
break;
case LAPDm_S_RNR:
/* FIXME */
break;
case LAPDm_S_REJ:
/* FIXME */
break;
}
return 0;
}
/* Receive a LAPDm I (Information) message from L1 */
static int lapdm_rx_i(struct msgb *msg, struct lapdm_msg_ctx *mctx)
{
struct lapdm_datalink *dl = mctx->dl;
uint8_t nr = LAPDm_CTRL_I_Nr(mctx->ctrl);
uint8_t ns = LAPDm_CTRL_I_Ns(mctx->ctrl);
uint8_t length;
int rc;
length = msg->l2h[2] >> 2;
/* FIXME: check for length > N201 */
if (length == 0) {
/* 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. */
return -EIO;
}
/* FIXME: 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. */
switch (dl->state) {
case LAPDm_STATE_IDLE:
/* FIXME: if P=1, respond DM with F=1 (5.2.2) */
/* 5.4.5 all other frame types shall be discarded */
break;
}
/* processing of Nr, Ns and P fields */
if (ns == dl->V_recv) {
/* FIXME: check for M bit! */
dl->V_recv = inc_mod8(dl->V_recv);
/* send a DATA INDICATION to L3 */
msg->l3h = msg->l2h + 2;
msgb_pull_l2h(msg);
rc = send_rslms_rll_l3(RSL_MT_DATA_IND, mctx, msg);
} else {
LOGP(DLAPDM, LOGL_INFO, "N(s) sequence error: Ns=%u, "
"V_recv=%u ", ns, dl->V_recv);
/* FIXME: 5.7.1: N(s) sequence error */
/* discard data */
return -EIO;
}
/* Check for P bit */
if (LAPDm_CTRL_PF_BIT(mctx->ctrl)) {
/* 5.5.2.1 */
/* FIXME: check ifwe are in own receiver busy */
/* FIXME: Send RR with F=1 */
rc = lapdm_send_rr(mctx, 1);
} else {
/* 5.5.2.2 */
/* FIXME: check ifwe are in own receiver busy */
//if (we_have_I_frame_pending) {
if (0) {
/* FIXME: send that I frame with Nr=Vr */
} else {
/* Send RR with F=0 */
rc = lapdm_send_rr(mctx, 0);
}
}
if (dl->state != LAPDm_STATE_TIMER_RECOV) {
/* When not in the timer recovery condition, the data
* link layer entity shall reset the timer T200 on
* receipt of a valid I frame with N(R) higher than V(A) */
if (nr > dl->V_ack) {
/* FIXME: 5.5.3.1 Note 1 + 2 */
bsc_del_timer(&dl->t200);
/* FIXME: if there are outstanding I frames
* still unacknowledged, the data link layer
* entity shall set timer T200 */
}
/* FIXME: 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. */
}
/* V(A) shall be set to the value of N(R) */
dl->V_ack = LAPDm_CTRL_I_Nr(mctx->ctrl);
return rc;
}
/* Receive a LAPDm message from L1 */
static int lapdm_ph_data_ind(struct msgb *msg, struct lapdm_msg_ctx *mctx)
{
int rc;
if (LAPDm_CTRL_is_U(mctx->ctrl))
rc = lapdm_rx_u(msg, mctx);
else if (LAPDm_CTRL_is_S(mctx->ctrl))
rc = lapdm_rx_s(msg, mctx);
else if (LAPDm_CTRL_is_I(mctx->ctrl))
rc = lapdm_rx_i(msg, mctx);
else {
LOGP(DLAPDM, LOGL_ERROR, "unknown LAPDm format ");
rc = -EINVAL;
}
return rc;
}
/* input into layer2 (from layer 1) */
int l2_ph_data_ind(struct msgb *msg, struct lapdm_entity *le, struct l1ctl_info_dl *l1i)
{
uint8_t cbits = l1i->chan_nr >> 3;
uint8_t sapi = l1i->link_id & 7;
struct lapdm_msg_ctx mctx;
int rc;
/* when we reach here, we have a msgb with l2h pointing to the raw
* 23byte mac block. The l1h has already been purged. */
mctx.dl = datalink_for_sapi(le, sapi);
mctx.chan_nr = l1i->chan_nr;
mctx.link_id = l1i->link_id;
mctx.addr = mctx.ctrl = 0;
/* check for L1 chan_nr/link_id and determine LAPDm hdr format */
if (cbits == 0x10 || cbits == 0x12) {
/* Format Bbis is used on BCCH and CCCH(PCH, NCH and AGCH) */
mctx.lapdm_fmt = LAPDm_FMT_Bbis;
} else {
if (mctx.link_id & 0x40) {
/* It was received from network on SACCH, thus
* lapdm_fmt must be B4 */
mctx.lapdm_fmt = LAPDm_FMT_B4;
DEBUGP(DLAPDM, "fmt=B4\n");
/* SACCH frames have a two-byte L1 header that
* OsmocomBB L1 doesn't strip */
msg->l2h += 2;
} else {
mctx.lapdm_fmt = LAPDm_FMT_B;
DEBUGP(DLAPDM, "fmt=B\n");
}
}
switch (mctx.lapdm_fmt) {
case LAPDm_FMT_A:
case LAPDm_FMT_B:
case LAPDm_FMT_B4:
mctx.addr = msg->l2h[0];
if (!(mctx.addr & 0x01)) {
LOGP(DLAPDM, LOGL_ERROR, "we don't support "
"multibyte addresses (discarding)\n");
return -EINVAL;
}
mctx.ctrl = msg->l2h[1];
/* obtain SAPI from address field */
mctx.link_id |= LAPDm_ADDR_SAPI(mctx.addr);
rc = lapdm_ph_data_ind(msg, &mctx);
break;
case LAPDm_FMT_Bter:
/* FIXME */
break;
case LAPDm_FMT_Bbis:
/* directly pass up to layer3 */
DEBUGP(DLAPDM, "fmt=Bbis UI\n");
msg->l3h = msg->l2h;
msgb_pull_l2h(msg);
rc = send_rslms_rll_l3(RSL_MT_UNIT_DATA_IND, &mctx, msg);
break;
}
return rc;
}
/* L3 -> L2 / RSLMS -> LAPDm */
/* L3 requests establishment of data link */
static int rslms_rx_rll_est_req(struct msgb *msg, struct lapdm_datalink *dl)
{
struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
uint8_t chan_nr = rllh->chan_nr;
uint8_t link_id = rllh->link_id;
uint8_t sapi = rllh->link_id & 7;
struct tlv_parsed tv;
uint8_t len;
DEBUGP(DRSL, "RSL_MT_EST_REQ ");
rsl_tlv_parse(&tv, rllh->data, msgb_l2len(msg)-sizeof(*rllh));
if (TLVP_PRESENT(&tv, RSL_IE_L3_INFO)) {
/* contention resolution establishment procedure */
if (dl->state != LAPDm_STATE_IDLE) {
/* 5.4.1.4: The data link layer shall, however, ignore any such
* service request if it is not in the idle state when the
* request is received. */
LOGP(DRSL, LOGL_INFO,
"DL state != IDLE (discarding)\n");
msgb_free(msg);
return 0;
}
if (sapi != 0) {
/* According to clause 6, the contention resolution
* procedure is only permitted with SAPI value 0 */
LOGP(DRSL, LOGL_INFO, "SAPI != 0 but contention"
"resolution (discarding)\n");
msgb_free(msg);
return -EINVAL;
}
/* transmit a SABM command with the P bit set to "1". The SABM
* command shall contain the layer 3 message unit */
len = LAPDm_LEN(TLVP_LEN(&tv, RSL_IE_L3_INFO));
/* FIXME: store information field in dl entity */
} else {
/* normal establishment procedure */
len = LAPDm_LEN(0);
}
/* Remove RLL header from msgb */
msgb_pull_l2h(msg);
/* Push LAPDm header on msgb */
msg->l2h = msgb_push(msg, 3);
msg->l2h[0] = LAPDm_ADDR(LAPDm_LPD_NORMAL, sapi, CR_MS2BS_CMD);
msg->l2h[1] = LAPDm_CTRL_U(LAPDm_U_SABM, 1);
msg->l2h[2] = len;
/* Tramsmit and start T200 */
dl->state = LAPDm_STATE_SABM_SENT;
bsc_schedule_timer(&dl->t200, T200);
return tx_ph_data_req_pad(dl->entity->ms, msg, chan_nr, link_id);
}
/* L3 requests transfer of unnumbered information */
static int rslms_rx_rll_udata_req(struct msgb *msg, struct lapdm_datalink *dl)
{
struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
uint8_t chan_nr = rllh->chan_nr;
uint8_t link_id = rllh->link_id;
uint8_t sapi = link_id & 7;
struct tlv_parsed tv;
rsl_tlv_parse(&tv, rllh->data, msgb_l2len(msg)-sizeof(*rllh));
/* Remove RLL header from msgb */
msgb_pull_l2h(msg);
/* Push LAPDm header on msgb */
msg->l2h = msgb_push(msg, 3);
msg->l2h[0] = LAPDm_ADDR(LAPDm_LPD_NORMAL, sapi, CR_MS2BS_CMD);
msg->l2h[1] = LAPDm_CTRL_U(LAPDm_U_SABM, 1);
msg->l2h[2] = LAPDm_LEN(TLVP_LEN(&tv, RSL_IE_L3_INFO));
/* Tramsmit and start T200 */
bsc_schedule_timer(&dl->t200, T200);
return tx_ph_data_req_pad(dl->entity->ms, msg, chan_nr, link_id);
}
/* L3 requests transfer of acknowledged information */
static int rslms_rx_rll_data_req(struct msgb *msg, struct lapdm_datalink *dl)
{
struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
uint8_t chan_nr = rllh->chan_nr;
uint8_t link_id = rllh->link_id;
uint8_t sapi = rllh->link_id & 7;
struct tlv_parsed tv;
switch (dl->state) {
case LAPDm_STATE_MF_EST:
break;
default:
LOGP(DRSL, LOGL_NOTICE, "refusing RLL DATA REQ during "
"DL state %u\n", dl->state);
return -EIO;
break;
}
/* FIXME: check if the layer3 message length exceeds N201 */
rsl_tlv_parse(&tv, rllh->data, msgb_l2len(msg)-sizeof(*rllh));
/* Remove the RSL/RLL header */
msgb_pull_l2h(msg);
/* Push the LAPDm header */
msg->l2h = msgb_put(msg, 3);
msg->l2h[0] = LAPDm_ADDR(LAPDm_LPD_NORMAL, sapi, CR_MS2BS_CMD);
msg->l2h[1] = LAPDm_CTRL_I(dl->V_recv, dl->V_send, 0);
msg->l2h[2] = LAPDm_LEN(TLVP_LEN(&tv, RSL_IE_L3_INFO));
/* The value of the send state variable V(S) shall be incremented by 1
* at the end of the transmission of the I frame */
dl->V_send = inc_mod8(dl->V_send);
/* If timer T200 is not running at the time right before transmitting a
* frame, when the PH-READY-TO-SEND primitive is received from the
* physical layer., it shall be set. */
if (!bsc_timer_pending(&dl->t200))
bsc_schedule_timer(&dl->t200, T200);
/* FIXME: 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. */
return tx_ph_data_req_pad(dl->entity->ms, msg, chan_nr, link_id);
}
/* incoming RSLms RLL message from L3 */
static int rslms_rx_rll(struct msgb *msg, struct osmocom_ms *ms)
{
struct abis_rsl_rll_hdr *rllh = msgb_l2(msg);
int rc = 0;
uint8_t sapi = rllh->link_id & 7;
struct lapdm_entity *le;
struct lapdm_datalink *dl;
if (rllh->link_id & 0x40)
le = &ms->l2_entity.lapdm_acch;
else
le = &ms->l2_entity.lapdm_dcch;
dl = datalink_for_sapi(le, sapi);
switch (rllh->c.msg_type) {
case RSL_MT_UNIT_DATA_REQ:
/* create and send UI command */
rc = rslms_rx_rll_udata_req(msg, dl);
break;
case RSL_MT_EST_REQ:
/* create and send SABM command */
rc = rslms_rx_rll_est_req(msg, dl);
break;
case RSL_MT_DATA_REQ:
/* create and send I command */
rc = rslms_rx_rll_data_req(msg, dl);
break;
case RSL_MT_REL_REQ:
/* FIXME: create and send DISC command */
default:
LOGP(DRSL, LOGL_NOTICE, "unknown RLL message type 0x%02x\n",
rllh->c.msg_type);
break;
}
return rc;
}
/* input into layer2 (from layer 3) */
int rslms_recvmsg(struct msgb *msg, struct osmocom_ms *ms)
{
struct abis_rsl_common_hdr *rslh = msgb_l2(msg);
int rc = 0;
switch (rslh->msg_discr & 0xfe) {
case ABIS_RSL_MDISC_RLL:
DEBUGP(DRSL, "rslms_recvmsg(ABIS_RSL_MDISC_RLL)\n");
rc = rslms_rx_rll(msg, ms);
break;
default:
LOGP(DRSL, LOGL_ERROR, "unknown RSLms message "
"discriminator 0x%02x", rslh->msg_discr);
msgb_free(msg);
return -EINVAL;
}
return rc;
}
/* input function that L2 calls when sending messages up to L3 */
int rslms_sendmsg(struct msgb *msg, struct osmocom_ms *ms)
{
if (!ms->l2_entity.msg_handler)
return -EIO;
/* call the layer2 message handler that is registered */
return ms->l2_entity.msg_handler(msg, ms);
}
/* register message handler for messages that are sent from L2->L3 */
int osmol2_register_handler(struct osmocom_ms *ms, osmol2_cb_t cb)
{
ms->l2_entity.msg_handler = cb;
return 0;
}
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