osmo-v5/src/v5x_le_pstn_fsm.c

/* ITU-T G.964 Section 13 PSTN signalling protocol specification - LE */

/* (C) 2022 by Andreas Eversberg <jolly@eversberg.eu>
 *
 * All Rights Reserved
 *
 * SPDX-License-Identifier: GPL-2.0+
 *
 * 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.
 *
 */

/***********************************************************************/
/* internal data structures */
/***********************************************************************/

#include <errno.h>
#include <arpa/inet.h>

#include <osmocom/core/linuxlist.h>
#include <osmocom/gsm/tlv.h>

#include "v5x_internal.h"
#include "v5x_protocol.h"
#include "v5x_le_pstn_fsm.h"
#include "v5x_le_management.h"
#include "logging.h"

/* Table 28/G.964 Timers in the LE */
#define TIMEOUT_T1	2 /* default */
#define TIMEOUT_T3	2
#define TIMEOUT_T4	2
#define TIMEOUT_Tr	5
#define TIMEOUT_Tt	10

#define S(x)    (1 << (x))

/***********************************************************************/
/* state names, event names, primitives, ... */
/***********************************************************************/

/* 13.2.1.2 PSTN protocol FSM - LE(PSTN) */
enum v5x_le_pstn_state {
	V5x_LE_PTSN_S_LE0_OUT_OF_SERVICE,		/* LE0 */
	V5x_LE_PTSN_S_LE1_NULL,				/* LE1 */
	V5x_LE_PTSN_S_LE2_PATH_INITIATED_LE,		/* LE2 */
	V5x_LE_PTSN_S_LE3_PATH_INITIATED_AN,		/* LE3 */
	V5x_LE_PTSN_S_LE4_PATH_ACTIVE,			/* LE4 */
	V5x_LE_PTSN_S_LE5_PATH_DICONNECT_REQ,		/* LE5 */
	V5x_LE_PTSN_S_LE6_PORT_BLOCKED,			/* LE6 */
};

enum v5x_le_pstn_fsm_event {
	/* inbound function elements from AN (Table 3/G.964) */
	V5x_PSTN_LE_FE_establish_req,
	V5x_PSTN_LE_FE_establish_ack_req,
	V5x_PSTN_LE_FE_line_signal_req,
	V5x_PSTN_LE_FE_protocol_param_req,
	V5x_PSTN_LE_FE_disconnect_req,
	V5x_PSTN_LE_FE_disconnect_compl_req,
	/* inbound messages from AN (Table 3/G.964) */
	V5x_PSTN_LE_DISCONNECT,
	V5x_PSTN_LE_DISCONNECT_COMPL,
	V5x_PSTN_LE_ESTABLISH,
	V5x_PSTN_LE_ESTABLISH_ACK,
	V5x_PSTN_LE_SIGNAL,
	V5x_PSTN_LE_SIGNAL_ACK,
	V5x_PSTN_LE_STATUS,
	/* timer events (Table 3/G.964) */
	V5x_PSTN_LE_TIMEOUT_T1,
	V5x_PSTN_LE_TIMEOUT_T3,
	V5x_PSTN_LE_TIMEOUT_T4,
	V5x_PSTN_LE_TIMEOUT_Tr,
	V5x_PSTN_LE_TIMEOUT_Tt,
	/* inbound primitives from Mgmt (Table 3/G.964) */
	V5x_PSTN_LE_MDU_CTRL_port_blocked,
	V5x_PSTN_LE_MDU_CTRL_port_unblocked,
	V5x_PSTN_LE_MDU_CTRL_restart_req,
	V5x_PSTN_LE_MDU_CTRL_restart_compl_req,
};

static const struct value_string v5x_ctrl_le_port_fsm_event_names[] = {
	{ V5x_PSTN_LE_FE_establish_req,				"FE-establish_request" },
	{ V5x_PSTN_LE_FE_establish_ack_req,			"FE-establish_acknowledge_request" },
	{ V5x_PSTN_LE_FE_line_signal_req,			"FE-line_signal_request" },
	{ V5x_PSTN_LE_FE_protocol_param_req,			"FE-protocol_parameter_request" },
	{ V5x_PSTN_LE_FE_disconnect_req,			"FE-disconnect_request" },
	{ V5x_PSTN_LE_FE_disconnect_compl_req,			"FE-disconnect_complete_request" },
	{ V5x_PSTN_LE_DISCONNECT,				"DISCONNECT" },
	{ V5x_PSTN_LE_DISCONNECT_COMPL,				"DISCONNECT COMPLETE" },
	{ V5x_PSTN_LE_ESTABLISH,				"ESTABLISH " },
	{ V5x_PSTN_LE_ESTABLISH_ACK,				"ESTABLISH ACK" },
	{ V5x_PSTN_LE_SIGNAL,					"SIGNAL" },
	{ V5x_PSTN_LE_SIGNAL_ACK,				"SIGNAL_ACK" },
	{ V5x_PSTN_LE_STATUS,					"STATUS" },
	{ V5x_PSTN_LE_TIMEOUT_T1,				"TIMEOUT T1" },
	{ V5x_PSTN_LE_TIMEOUT_T3,				"TIMEOUT T3" },
	{ V5x_PSTN_LE_TIMEOUT_T4,				"TIMEOUT T4" },
	{ V5x_PSTN_LE_TIMEOUT_Tr,				"TIMEOUT Tr" },
	{ V5x_PSTN_LE_TIMEOUT_Tt,				"TIMEOUT Tt" },
	{ V5x_PSTN_LE_MDU_CTRL_port_blocked,			"MDU-CTRL (port blocked)" },
	{ V5x_PSTN_LE_MDU_CTRL_port_unblocked,			"MDU-CTRL (port unblocked)" },
	{ V5x_PSTN_LE_MDU_CTRL_restart_req,			"MDU-CTRL (restart request)" },
	{ V5x_PSTN_LE_MDU_CTRL_restart_compl_req,		"MDU-CTRL (restart complete)" },
	{ 0, NULL }
};

/***********************************************************************
 * V5 Message encoding / sending
 ***********************************************************************/

/* G.964 Section 13.3.1 / Table 5 */
static struct msgb *v5x_enc_establish(struct v5x_user_port *v5up, uint8_t *cond_ie, uint8_t cond_len)
{
	struct v5x_l3_hdr *l3h;
	struct msgb *msg = msgb_alloc_v5x();
	if (!msg)
		return NULL;

	l3h = (struct v5x_l3_hdr *) msgb_put(msg, sizeof(*l3h));
	l3h->pdisc = V5X_CTRL_PDISC;
	l3h->l3_addr = htons(v5x_l3_addr_enc(v5up->nr, false));
	l3h->msg_type = V5X_CTRL_MSGT_ESTABLISH;

	/* optional conditional IE */
	if (cond_ie && cond_len)
		memcpy(msgb_put(msg, cond_len), cond_ie, cond_len);

	return msg;
}

/* G.964 Section 13.3.1 / Table 6 */
static struct msgb *v5x_enc_establish_ack(struct v5x_user_port *v5up, uint8_t *cond_ie, uint8_t cond_len)
{
	struct v5x_l3_hdr *l3h;
	struct msgb *msg = msgb_alloc_v5x();
	if (!msg)
		return NULL;

	l3h = (struct v5x_l3_hdr *) msgb_put(msg, sizeof(*l3h));
	l3h->pdisc = V5X_CTRL_PDISC;
	l3h->l3_addr = htons(v5x_l3_addr_enc(v5up->nr, false));
	l3h->msg_type = V5X_CTRL_MSGT_ESTABLISH_ACK;

	/* optional conditional IE */
	if (cond_ie && cond_len)
		memcpy(msgb_put(msg, cond_len), cond_ie, cond_len);

	return msg;
}

/* G.964 Section 13.3.1 / Table 7 */
static struct msgb *v5x_enc_signal(struct v5x_user_port *v5up, uint8_t seq_nr, uint8_t *cond_ie, uint8_t cond_len)
{
	uint8_t seq_ie = seq_nr | 0x80;
	struct v5x_l3_hdr *l3h;
	struct msgb *msg = msgb_alloc_v5x();
	if (!msg)
		return NULL;

	l3h = (struct v5x_l3_hdr *) msgb_put(msg, sizeof(*l3h));
	l3h->pdisc = V5X_CTRL_PDISC;
	l3h->l3_addr = htons(v5x_l3_addr_enc(v5up->nr, false));
	l3h->msg_type = V5X_CTRL_MSGT_SIGNAL;

	/* Sequence-number */
	msgb_tlv_put(msg, V5X_CTRL_IEI_SEQUENCE_NR, 1, &seq_ie);
	/* manatory conditional IE */
	OSMO_ASSERT(cond_ie && cond_len);
	memcpy(msgb_put(msg, cond_len), cond_ie, cond_len);

	return msg;
}

/* G.964 Section 13.3.1 / Table 8 */
static struct msgb *v5x_enc_signal_ack(struct v5x_user_port *v5up, uint8_t seq_nr)
{
	uint8_t seq_ie = seq_nr | 0x80;
	struct v5x_l3_hdr *l3h;
	struct msgb *msg = msgb_alloc_v5x();
	if (!msg)
		return NULL;

	l3h = (struct v5x_l3_hdr *) msgb_put(msg, sizeof(*l3h));
	l3h->pdisc = V5X_CTRL_PDISC;
	l3h->l3_addr = htons(v5x_l3_addr_enc(v5up->nr, false));
	l3h->msg_type = V5X_CTRL_MSGT_SIGNAL_ACK;

	/* Sequence-number */
	msgb_tlv_put(msg, V5X_CTRL_IEI_SEQUENCE_NR, 1, &seq_ie);

	return msg;
}

/* G.964 Section 13.3.1 / Table 10 */
static struct msgb *v5x_enc_status_enquiry(struct v5x_user_port *v5up)
{
	struct v5x_l3_hdr *l3h;
	struct msgb *msg = msgb_alloc_v5x();
	if (!msg)
		return NULL;

	l3h = (struct v5x_l3_hdr *) msgb_put(msg, sizeof(*l3h));
	l3h->pdisc = V5X_CTRL_PDISC;
	l3h->l3_addr = htons(v5x_l3_addr_enc(v5up->nr, false));
	l3h->msg_type = V5X_CTRL_MSGT_STATUS_ENQUIRY;

	return msg;
}

/* G.964 Section 13.3.1 / Table 11 */
static struct msgb *v5x_enc_disconnect(struct v5x_user_port *v5up, uint8_t *steady_ie, uint8_t steady_len)
{
	struct v5x_l3_hdr *l3h;
	struct msgb *msg = msgb_alloc_v5x();
	if (!msg)
		return NULL;

	l3h = (struct v5x_l3_hdr *) msgb_put(msg, sizeof(*l3h));
	l3h->pdisc = V5X_CTRL_PDISC;
	l3h->l3_addr = htons(v5x_l3_addr_enc(v5up->nr, false));
	l3h->msg_type = V5X_CTRL_MSGT_DISCONNECT;

	/* optional conditional IE */
	if (steady_ie && steady_len)
		memcpy(msgb_put(msg, steady_len), steady_ie, steady_len);

	return msg;
}

/* G.964 Section 13.3.1 / Table 12 */
static struct msgb *v5x_enc_disconnect_compl(struct v5x_user_port *v5up, uint8_t *steady_ie, uint8_t steady_len)
{
	struct v5x_l3_hdr *l3h;
	struct msgb *msg = msgb_alloc_v5x();
	if (!msg)
		return NULL;

	l3h = (struct v5x_l3_hdr *) msgb_put(msg, sizeof(*l3h));
	l3h->pdisc = V5X_CTRL_PDISC;
	l3h->l3_addr = htons(v5x_l3_addr_enc(v5up->nr, false));
	l3h->msg_type = V5X_CTRL_MSGT_DISCONNECT_COMPLETE;

	/* optional conditional IE */
	if (steady_ie && steady_len)
		memcpy(msgb_put(msg, steady_len), steady_ie, steady_len);

	return msg;
}

/* G.964 Section 13.3.1 / Table 13 */
static struct msgb *v5x_enc_protocol_param(struct v5x_user_port *v5up, uint8_t seq_nr, uint8_t *cond_ie, uint8_t cond_len)
{
	uint8_t seq_ie = seq_nr | 0x80;
	struct v5x_l3_hdr *l3h;
	struct msgb *msg = msgb_alloc_v5x();
	if (!msg)
		return NULL;

	l3h = (struct v5x_l3_hdr *) msgb_put(msg, sizeof(*l3h));
	l3h->pdisc = V5X_CTRL_PDISC;
	l3h->l3_addr = htons(v5x_l3_addr_enc(v5up->nr, false));
	l3h->msg_type = V5X_CTRL_MSGT_PROTOCOL_PARAMETER;

	/* Sequence-number */
	msgb_tlv_put(msg, V5X_CTRL_IEI_SEQUENCE_NR, 1, &seq_ie);
	/* manatory conditional IE */
	OSMO_ASSERT(cond_ie && cond_len);
	memcpy(msgb_put(msg, cond_len), cond_ie, cond_len);

	return msg;
}

/***********************************************************************/
/* upper layer interface */
/***********************************************************************/

static void rcv_fe(struct osmo_fsm_inst *fi, enum v5x_fe_prim prim, const struct tlv_parsed *tp)
{
	struct v5x_pstn_proto *pstn = fi->priv;
	struct msgb *msg;
	uint8_t *tlv, len;

	msg = msgb_alloc_v5x();
	OSMO_ASSERT(msg);

	/* add IE, if tp was given */
	if (tp) {
		/* single octet */
		if (TLVP_PRESENT(tp, V5X_CTRL_IEI_PULSE_NOTIFICATION))
			*msgb_put(msg, 1) = *TLVP_VAL(tp, V5X_CTRL_IEI_PULSE_NOTIFICATION);
		if (TLVP_PRESENT(tp, V5X_CTRL_IEI_LINE_INFORMATION))
			*msgb_put(msg, 1) = *TLVP_VAL(tp, V5X_CTRL_IEI_LINE_INFORMATION);
		if (TLVP_PRESENT(tp, V5X_CTRL_IEI_SEQUENCE_RESPONSE))
			*msgb_put(msg, 1) = *TLVP_VAL(tp, V5X_CTRL_IEI_SEQUENCE_RESPONSE);
		/* multiple octets */
		if (TLVP_PRESENT(tp, V5X_CTRL_IEI_PULSED_SIGNAL)) {
			len = TLVP_LEN(tp, V5X_CTRL_IEI_PULSED_SIGNAL);
			tlv = msgb_put(msg, 2 + len);
			tlv[0] = V5X_CTRL_IEI_PULSED_SIGNAL;
			tlv[1] = len;
			memcpy(tlv + 2, TLVP_VAL(tp, V5X_CTRL_IEI_PULSED_SIGNAL), len);
		}
		if (TLVP_PRESENT(tp, V5X_CTRL_IEI_STEADY_SIGNAL)) {
			len = TLVP_LEN(tp, V5X_CTRL_IEI_STEADY_SIGNAL);
			tlv = msgb_put(msg, 2 + len);
			tlv[0] = V5X_CTRL_IEI_STEADY_SIGNAL;
			tlv[1] = len;
			memcpy(tlv + 2, TLVP_VAL(tp, V5X_CTRL_IEI_STEADY_SIGNAL), len);
		}
		if (TLVP_PRESENT(tp, V5X_CTRL_IEI_DIGIT_SIGNAL)) {
			len = TLVP_LEN(tp, V5X_CTRL_IEI_DIGIT_SIGNAL);
			tlv = msgb_put(msg, 2 + len);
			tlv[0] = V5X_CTRL_IEI_DIGIT_SIGNAL;
			tlv[1] = len;
			memcpy(tlv + 2, TLVP_VAL(tp, V5X_CTRL_IEI_DIGIT_SIGNAL), len);
		}
		if (TLVP_PRESENT(tp, V5X_CTRL_IEI_RESOURCE_UNAVAILABLE)) {
			len = TLVP_LEN(tp, V5X_CTRL_IEI_RESOURCE_UNAVAILABLE);
			tlv = msgb_put(msg, 2 + len);
			tlv[0] = V5X_CTRL_IEI_RESOURCE_UNAVAILABLE;
			tlv[1] = len;
			memcpy(tlv + 2, TLVP_VAL(tp, V5X_CTRL_IEI_RESOURCE_UNAVAILABLE), len);
		}
		if (TLVP_PRESENT(tp, V5X_CTRL_IEI_METERING_REPORT)) {
			len = TLVP_LEN(tp, V5X_CTRL_IEI_METERING_REPORT);
			tlv = msgb_put(msg, 2 + len);
			tlv[0] = V5X_CTRL_IEI_METERING_REPORT;
			tlv[1] = len;
			memcpy(tlv + 2, TLVP_VAL(tp, V5X_CTRL_IEI_METERING_REPORT), len);
		}
	}

	v5x_le_pstn_fe_rcv(pstn->v5up, prim, msg);
}

static void rcv_mdu(struct osmo_fsm_inst *fi, enum v5x_mgmt_prim prim)
{
	struct v5x_pstn_proto *pstn = fi->priv;

	v5x_le_pstn_mdu_rcv(pstn->v5up, prim);
}

void v5x_le_pstn_fe_snd(struct v5x_user_port *v5up, enum v5x_fe_prim prim, struct msgb *msg)
{
	struct v5x_pstn_proto *pstn = v5up->pstn.proto;
	struct osmo_fsm_inst *fi = pstn->fi;
	enum v5x_le_pstn_fsm_event event;
	int rc;

	OSMO_ASSERT(msg);

	switch (prim) {
	case FE_establish_req:
		event = V5x_PSTN_LE_FE_establish_req;
		break;
        case FE_establish_ack_req:
		event = V5x_PSTN_LE_FE_establish_ack_req;
		break;
        case FE_line_signal_req:
		event = V5x_PSTN_LE_FE_line_signal_req;
		break;
        case FE_protocol_param_req:
		event = V5x_PSTN_LE_FE_protocol_param_req;
		break;
        case FE_disconnect_req:
		event = V5x_PSTN_LE_FE_disconnect_req;
		break;
        case FE_disconnect_compl_req:
		event = V5x_PSTN_LE_FE_disconnect_compl_req;
		break;
	default:
		LOGPFSML(v5up->port_fi, LOGL_NOTICE, "Got invalid prim %d at this protocol\n", prim);
		return;
	}

	/* send event to FSM */
	rc = osmo_fsm_inst_dispatch(fi, event, msg);
	if (rc < 0)
		msgb_free(msg);
}

void v5x_le_pstn_mdu_snd(struct v5x_user_port *v5up, enum v5x_mgmt_prim prim)
{
	struct v5x_pstn_proto *pstn = v5up->pstn.proto;
	struct osmo_fsm_inst *fi = pstn->fi;
	enum v5x_le_pstn_fsm_event event;

	switch (prim) {
        case MDU_CTRL_port_blocked:
		event = V5x_PSTN_LE_MDU_CTRL_port_blocked;
		break;
        case MDU_CTRL_port_unblocked:
		event = V5x_PSTN_LE_MDU_CTRL_port_unblocked;
		break;
        case MDU_CTRL_port_restart_req:
		event = V5x_PSTN_LE_MDU_CTRL_restart_req;
		break;
        case MDU_CTRL_port_restart_compl:
		event = V5x_PSTN_LE_MDU_CTRL_restart_compl_req;
		break;
	default:
		LOGPFSML(v5up->port_fi, LOGL_NOTICE, "Got invalid prim %d at this protocol\n", prim);
		return;
	}

	/* send event to FSM */
	osmo_fsm_inst_dispatch(fi, event, NULL);
}

/***********************************************************************/
/* lower layer interface */
/***********************************************************************/

static void dl_send(struct osmo_fsm_inst *fi, struct msgb *msg)
{
	struct v5x_pstn_proto *pstn = fi->priv;

	v5x_dl_snd(pstn->v5up->interface, V5X_DLADDR_PSTN, msg);
}

/***********************************************************************/
/* PSTN state FSM */
/***********************************************************************/

static void start_timer_Tr(struct v5x_pstn_proto *pstn)
{
	LOGPFSML(pstn->fi, LOGL_DEBUG, "Start timer Tr\n");
	osmo_timer_schedule(&pstn->timer_Tr, TIMEOUT_Tr, 0);
}

static void start_timer_Tt(struct v5x_pstn_proto *pstn)
{
	LOGPFSML(pstn->fi, LOGL_DEBUG, "Start timer Tt\n");
	osmo_timer_schedule(&pstn->timer_Tt, TIMEOUT_Tt, 0);
}

static void stop_timer_Tr(struct v5x_pstn_proto *pstn)
{
	if (osmo_timer_pending(&pstn->timer_Tr)) {
		LOGPFSML(pstn->fi, LOGL_DEBUG, "Stop timer Tr\n");
		osmo_timer_del(&pstn->timer_Tr);
	}
}

static void stop_timer_Tt(struct v5x_pstn_proto *pstn)
{
	if (osmo_timer_pending(&pstn->timer_Tt)) {
		LOGPFSML(pstn->fi, LOGL_DEBUG, "Stop timer Tt\n");
		osmo_timer_del(&pstn->timer_Tt);
	}
}

static void stop_timer(struct osmo_fsm_inst *fi)
{
	struct v5x_pstn_proto *pstn = fi->priv;

	LOGPFSML(fi, LOGL_DEBUG, "Stop all timers\n");
	osmo_timer_del(&fi->timer);
	stop_timer_Tr(pstn);
	stop_timer_Tt(pstn);
}

static void start_timer(struct osmo_fsm_inst *fi, enum v5x_le_pstn_fsm_event event, int count)
{
	struct v5x_pstn_proto *pstn = fi->priv;
	int timeout = 0;
	const char *timer_name = NULL;

	switch (event) {
	case V5x_PSTN_LE_TIMEOUT_T1:
		timer_name = "T1";
		timeout = TIMEOUT_T1;
		fi->T = 1;
		break;
	case V5x_PSTN_LE_TIMEOUT_T3:
		timer_name = "T3";
		timeout = TIMEOUT_T3;
		fi->T = 3;
		break;
	case V5x_PSTN_LE_TIMEOUT_T4:
		timer_name = "T4";
		timeout = TIMEOUT_T4;
		fi->T = 4;
		break;
	default:
		OSMO_ASSERT(0);
	}

	LOGPFSML(fi, LOGL_DEBUG, "Start timer %s (count = %d)\n", timer_name, count);
	pstn->timeout_event = event;
	pstn->timeout_count = count;
	osmo_timer_schedule(&fi->timer, timeout, 0);
}

static int v5x_le_pstn_fsm_timer_cb(struct osmo_fsm_inst *fi)
{
	struct v5x_pstn_proto *pstn = fi->priv;

	osmo_fsm_inst_dispatch(fi, pstn->timeout_event, NULL);

	return 0;
}

static void timeout_Tr_cb(void *data)
{
	struct v5x_pstn_proto *pstn = data;

	osmo_fsm_inst_dispatch(pstn->fi, V5x_PSTN_LE_TIMEOUT_Tr, NULL);
}

static void timeout_Tt_cb(void *data)
{
	struct v5x_pstn_proto *pstn = data;

	osmo_fsm_inst_dispatch(pstn->fi, V5x_PSTN_LE_TIMEOUT_Tt, NULL);
}

static void do_status_enquiry(struct osmo_fsm_inst *fi)
{
	struct v5x_pstn_proto *pstn = fi->priv;

	LOGPFSML(fi, LOGL_NOTICE, "Received message not allowed in current state, sending status enquiry.\n");

	/* start T4 */
	start_timer(fi, V5x_PSTN_LE_TIMEOUT_T4, 1);
	/* send STATUS ENQUIRY */
	dl_send(fi, v5x_enc_status_enquiry(pstn->v5up));
}

static void do_establish_request(struct osmo_fsm_inst *fi, struct msgb *msg)
{
	struct v5x_pstn_proto *pstn = fi->priv;

	/* change state to LE2 */
	osmo_fsm_inst_state_chg(fi, V5x_LE_PTSN_S_LE2_PATH_INITIATED_LE, 0, 0);
	/* init sequence variables */
	pstn->S_s = pstn->S_a = pstn->S_r = 0;
	/* start T1 */
	start_timer(fi, V5x_PSTN_LE_TIMEOUT_T1, 1);
	/* store ESTABLISH message */
	if (pstn->tx_msg)
		msgb_free(pstn->tx_msg);
	pstn->tx_msg = msgb_copy(msg, NULL);
	/* send ESTABLISH */
	dl_send(fi, v5x_enc_establish(pstn->v5up, msg->data, msg->len));
	msgb_free(msg);
}

static void do_establish_indication(struct osmo_fsm_inst *fi, const struct tlv_parsed *tp)
{
	struct v5x_pstn_proto *pstn = fi->priv;

	/* init sequence variables */
	pstn->S_s = pstn->S_a = pstn->S_r = 0;
	/* send FE-establish_indication */
	rcv_fe(fi, FE_establish_ind, tp);
}

static void do_disconnect_complete(struct osmo_fsm_inst *fi, const struct tlv_parsed *tp)
{
	/* change state to LE1 */
	osmo_fsm_inst_state_chg(fi, V5x_LE_PTSN_S_LE1_NULL, 0, 0);
	/* stop all timers */
	stop_timer(fi);
	/* send FE-disconnect_complete_indication */
	rcv_fe(fi, FE_disconnect_compl_ind, tp);
}

static void do_disconnect_with_error(struct osmo_fsm_inst *fi)
{
	struct v5x_pstn_proto *pstn = fi->priv;

	/* change state to LE5 */
	osmo_fsm_inst_state_chg(fi, V5x_LE_PTSN_S_LE5_PATH_DICONNECT_REQ, 0, 0);
	/* stop all timers */
	stop_timer(fi);
	/* start T3 */
	start_timer(fi, V5x_PSTN_LE_TIMEOUT_T3, 1);
	/* store empty disconnect message */
	if (pstn->tx_msg) {
		msgb_free(pstn->tx_msg);
		pstn->tx_msg = NULL;
	}
	/* send DISCONNECT */
	dl_send(fi, v5x_enc_disconnect(pstn->v5up, NULL, 0));
	/* send MDU-error_indication */
	rcv_mdu(fi, MDU_error_ind);
}

static void do_block(struct osmo_fsm_inst *fi)
{
	/* change state to LE6 */
	osmo_fsm_inst_state_chg(fi, V5x_LE_PTSN_S_LE6_PORT_BLOCKED, 0, 0);
	/* stop all timers */
	stop_timer(fi);
	/* send FE-disconnect_complete_indication */
	rcv_fe(fi, FE_disconnect_compl_ind, NULL);
}

static void do_restart(struct osmo_fsm_inst *fi)
{
	/* change state to LE0 */
	osmo_fsm_inst_state_chg(fi, V5x_LE_PTSN_S_LE0_OUT_OF_SERVICE, 0, 0);
	/* send FE-disconnect_complete_indication */
	rcv_fe(fi, FE_disconnect_compl_ind, NULL);
	/* send MDU-CTRL (restart ack) */
	rcv_mdu(fi, MDU_CTRL_port_restart_ack);
}

static void pstn_le0_out_of_service(struct osmo_fsm_inst *fi, uint32_t event, void *data)
{
	struct v5x_pstn_proto *pstn = fi->priv;
	struct msgb *msg = data;
	const struct tlv_parsed *tp = data;
	uint8_t cause;

	switch (event) {
	case V5x_PSTN_LE_FE_establish_req:
		msgb_free(msg);
		/* ignore */
		break;
	case V5x_PSTN_LE_ESTABLISH:
	case V5x_PSTN_LE_DISCONNECT:
	case V5x_PSTN_LE_ESTABLISH_ACK:
	case V5x_PSTN_LE_SIGNAL:
	case V5x_PSTN_LE_SIGNAL_ACK:
		/* do several thing here */
		do_status_enquiry(fi);
		break;
	case V5x_PSTN_LE_DISCONNECT_COMPL:
		/* ignore */
		break;
	case V5x_PSTN_LE_FE_establish_ack_req:
		msgb_free(msg);
		/* ignore */
		break;
	case V5x_PSTN_LE_STATUS:
		cause = *TLVP_VAL(tp, V5X_CTRL_IEI_CAUSE) & 0x7f;
		if (cause == 0) {
			/* stop T4 */
			stop_timer(fi);
		} else {
			/* send MDU-error_indication */
			rcv_mdu(fi, MDU_error_ind);
		}
		break;
	case V5x_PSTN_LE_FE_protocol_param_req:
		msgb_free(msg);
		/* ignore */
		break;
	case V5x_PSTN_LE_FE_disconnect_req:
		msgb_free(msg);
		/* ignore */
		break;
	case V5x_PSTN_LE_MDU_CTRL_port_blocked:
		/* change state to LE6 */
		osmo_fsm_inst_state_chg(fi, V5x_LE_PTSN_S_LE6_PORT_BLOCKED, 0, 0);
		break;
	case V5x_PSTN_LE_MDU_CTRL_port_unblocked:
		/* ignore */
		break;
	case V5x_PSTN_LE_MDU_CTRL_restart_req:
		/* send MDU-CTRL (restart ack) */
		rcv_mdu(fi, MDU_CTRL_port_restart_ack);
		break;
	case V5x_PSTN_LE_MDU_CTRL_restart_compl_req:
		/* change state to LE1 */
		osmo_fsm_inst_state_chg(fi, V5x_LE_PTSN_S_LE1_NULL, 0, 0);
		break;
	case V5x_PSTN_LE_TIMEOUT_T4:
		/* first or second timeout ? */
		if (pstn->timeout_count <= 3) {
			/* start T4 */
			start_timer(fi, V5x_PSTN_LE_TIMEOUT_T4, pstn->timeout_count + 1);
			/* send STATUS ENQUIRY again */
			dl_send(fi, v5x_enc_status_enquiry(pstn->v5up));
		} else {
			/* send MDU-error_indication */
			rcv_mdu(fi, MDU_error_ind);
		}	
		break;
	default:
		OSMO_ASSERT(0);
	}
}

static void pstn_le1_null(struct osmo_fsm_inst *fi, uint32_t event, void *data)
{
	struct v5x_pstn_proto *pstn = fi->priv;
	struct msgb *msg = data;
	const struct tlv_parsed *tp = data;
	uint8_t cause;

	switch (event) {
	case V5x_PSTN_LE_FE_establish_req:
		/* do several thing here */
		do_establish_request(fi, msg);
		break;
	case V5x_PSTN_LE_ESTABLISH:
		/* change state to LE3 */
		osmo_fsm_inst_state_chg(fi, V5x_LE_PTSN_S_LE3_PATH_INITIATED_AN, 0, 0);
		/* do several thing here */
		do_establish_indication(fi, tp);
		break;
	case V5x_PSTN_LE_DISCONNECT:
		/* send DISCONNECT COMPLETE */
		dl_send(fi, v5x_enc_disconnect_compl(pstn->v5up, NULL, 0));
		break;
	case V5x_PSTN_LE_ESTABLISH_ACK:
	case V5x_PSTN_LE_SIGNAL:
	case V5x_PSTN_LE_SIGNAL_ACK:
		/* do several thing here */
		do_status_enquiry(fi);
		break;
	case V5x_PSTN_LE_STATUS:
		cause = *TLVP_VAL(tp, V5X_CTRL_IEI_CAUSE) & 0x7f;
		if (cause == 0) {
			/* stop T4 */
			stop_timer(fi);
		} else {
			/* do several thing here */
			do_disconnect_with_error(fi);
		}
		break;
	case V5x_PSTN_LE_FE_protocol_param_req:
		msgb_free(msg);
		/* ignore */
		break;
	case V5x_PSTN_LE_MDU_CTRL_port_blocked:
		/* do several thing here */
		do_block(fi);
		break;
	case V5x_PSTN_LE_MDU_CTRL_port_unblocked:
		/* ignore */
		break;
	case V5x_PSTN_LE_MDU_CTRL_restart_req:
		/* do several thing here */
		do_restart(fi);
		break;
	case V5x_PSTN_LE_TIMEOUT_T4:
		/* first or second timeout ? */
		if (pstn->timeout_count < 3) {
			/* start T4 */
			start_timer(fi, V5x_PSTN_LE_TIMEOUT_T4, pstn->timeout_count + 1);
			/* send STATUS ENQUIRY again */
			dl_send(fi, v5x_enc_status_enquiry(pstn->v5up));
		} else {
			/* do several thing here */
			do_disconnect_with_error(fi);
		}	
		break;
	default:
		OSMO_ASSERT(0);
	}
}

static void pstn_le2_path_initiated_le(struct osmo_fsm_inst *fi, uint32_t event, void *data)
{
	struct v5x_pstn_proto *pstn = fi->priv;
	struct msgb *msg = data;
	const struct tlv_parsed *tp = data;
	uint8_t cause;

	switch (event) {
	case V5x_PSTN_LE_ESTABLISH:
		/* do several thing here */
		do_establish_indication(fi, tp);
		break;
	case V5x_PSTN_LE_DISCONNECT:
		/* send DISCONNECT COMPLETE */
		dl_send(fi, v5x_enc_disconnect_compl(pstn->v5up, NULL, 0));
		/* do several thing here */
		do_disconnect_complete(fi, tp);
		break;
	case V5x_PSTN_LE_DISCONNECT_COMPL:
		/* do several thing here */
		do_disconnect_complete(fi, tp);
		break;
	case V5x_PSTN_LE_FE_establish_ack_req:
		/* change state to LE4 */
		osmo_fsm_inst_state_chg(fi, V5x_LE_PTSN_S_LE4_PATH_ACTIVE, 0, 0);
		/* stop T1 */
		stop_timer(fi);
		/* send ESTABLISH ACK */
		dl_send(fi, v5x_enc_establish_ack(pstn->v5up, msg->data, msg->len));
		msgb_free(msg);
		break;
	case V5x_PSTN_LE_ESTABLISH_ACK:
		/* change state to LE4 */
		osmo_fsm_inst_state_chg(fi, V5x_LE_PTSN_S_LE4_PATH_ACTIVE, 0, 0);
		/* stop T1 */
		stop_timer(fi);
		/* send FE-establish_acknowledge_indication */
		rcv_fe(fi, FE_establish_ack_ind, tp);
		break;
	case V5x_PSTN_LE_SIGNAL:
	case V5x_PSTN_LE_SIGNAL_ACK:
		/* do several thing here */
		do_status_enquiry(fi);
		break;
	case V5x_PSTN_LE_STATUS:
		cause = *TLVP_VAL(tp, V5X_CTRL_IEI_CAUSE) & 0x7f;
		if (cause == 0) {
			/* stop T4 */
			stop_timer(fi);
		} else {
			/* do several thing here */
			do_disconnect_with_error(fi);
		}
		break;
	case V5x_PSTN_LE_FE_protocol_param_req:
		msgb_free(msg);
		/* ignore */
		break;
	case V5x_PSTN_LE_FE_disconnect_req:
		/* change state to LE5 */
		osmo_fsm_inst_state_chg(fi, V5x_LE_PTSN_S_LE5_PATH_DICONNECT_REQ, 0, 0);
		/* stop all timers */
		stop_timer(fi);
		/* start T3 */
		start_timer(fi, V5x_PSTN_LE_TIMEOUT_T3, 2);
		/* store DISCONNECT message */
		if (pstn->tx_msg)
			msgb_free(pstn->tx_msg);
		pstn->tx_msg = msgb_copy(msg, NULL);
		/* send DISCONNECT */
		dl_send(fi, v5x_enc_disconnect(pstn->v5up, msg->data, msg->len));
		msgb_free(msg);
		break;
	case V5x_PSTN_LE_FE_disconnect_compl_req:
		// NOTE: The Table 31-32/G.964 is wrong at this point, there is no use here
		msgb_free(msg);
		/* ignore */
		break;
	case V5x_PSTN_LE_MDU_CTRL_port_blocked:
		/* do several thing here */
		do_block(fi);
		break;
	case V5x_PSTN_LE_MDU_CTRL_port_unblocked:
		/* ignore */
		break;
	case V5x_PSTN_LE_MDU_CTRL_restart_req:
		/* send DISCONNECT COMPLETE */
		dl_send(fi, v5x_enc_disconnect_compl(pstn->v5up, NULL, 0));
		/* do several thing here */
		do_restart(fi);
		break;
	case V5x_PSTN_LE_MDU_CTRL_restart_compl_req:
		/* ignore */
		break;
	case V5x_PSTN_LE_TIMEOUT_T1:
		/* first timeout ? */
		if (pstn->timeout_count == 1) {
			/* start T1 */
			start_timer(fi, V5x_PSTN_LE_TIMEOUT_T1, 2);
			/* send ESTABLISH again */
			OSMO_ASSERT(pstn->tx_msg);
			dl_send(fi, v5x_enc_establish(pstn->v5up, pstn->tx_msg->data, pstn->tx_msg->len));
		} else {
			/* do several thing here */
			do_disconnect_with_error(fi);
		}
		break;
	case V5x_PSTN_LE_TIMEOUT_T4:
		/* first or second timeout ? */
		if (pstn->timeout_count < 3) {
			/* start T4 */
			start_timer(fi, V5x_PSTN_LE_TIMEOUT_T4, pstn->timeout_count + 1);
			/* send STATUS ENQUIRY again */
			dl_send(fi, v5x_enc_status_enquiry(pstn->v5up));
		} else {
			/* do several thing here */
			do_disconnect_with_error(fi);
		}	
		break;
	default:
		OSMO_ASSERT(0);
	}
}

static void pstn_le3_path_initiated_an(struct osmo_fsm_inst *fi, uint32_t event, void *data)
{
	struct v5x_pstn_proto *pstn = fi->priv;
	struct msgb *msg = data;
	const struct tlv_parsed *tp = data;
	uint8_t cause;

	switch (event) {
	case V5x_PSTN_LE_FE_establish_req:
		/* do several thing here */
		do_establish_request(fi, msg);
		break;
	case V5x_PSTN_LE_ESTABLISH:
		/* do several thing here */
		do_establish_indication(fi, tp);
		break;
	case V5x_PSTN_LE_DISCONNECT:
		/* send DISCONNECT COMPLETE */
		dl_send(fi, v5x_enc_disconnect_compl(pstn->v5up, NULL, 0));
		/* do several thing here */
		do_disconnect_complete(fi, tp);
		break;
	case V5x_PSTN_LE_DISCONNECT_COMPL:
		/* do several thing here */
		do_disconnect_complete(fi, tp);
		break;
	case V5x_PSTN_LE_FE_establish_ack_req:
		/* change state to LE4 */
		osmo_fsm_inst_state_chg(fi, V5x_LE_PTSN_S_LE4_PATH_ACTIVE, 0, 0);
		/* send ESTABLISH ACK */
		dl_send(fi, v5x_enc_establish_ack(pstn->v5up, msg->data, msg->len));
		msgb_free(msg);
		break;
	case V5x_PSTN_LE_ESTABLISH_ACK:
	case V5x_PSTN_LE_SIGNAL:
	case V5x_PSTN_LE_SIGNAL_ACK:
		/* do several thing here */
		do_status_enquiry(fi);
		break;
	case V5x_PSTN_LE_STATUS:
		cause = *TLVP_VAL(tp, V5X_CTRL_IEI_CAUSE) & 0x7f;
		if (cause == 0) {
			/* stop T4 */
			stop_timer(fi);
		} else {
			/* do several thing here */
			do_disconnect_with_error(fi);
		}
		break;
	case V5x_PSTN_LE_FE_protocol_param_req:
		msgb_free(msg);
		/* ignore */
		break;
	case V5x_PSTN_LE_FE_disconnect_req:
		/* change state to LE5 */
		osmo_fsm_inst_state_chg(fi, V5x_LE_PTSN_S_LE5_PATH_DICONNECT_REQ, 0, 0);
		/* stop all timers */
		stop_timer(fi);
		/* start T3 */
		start_timer(fi, V5x_PSTN_LE_TIMEOUT_T3, 2);
		/* store DISCONNECT message */
		if (pstn->tx_msg)
			msgb_free(pstn->tx_msg);
		pstn->tx_msg = msgb_copy(msg, NULL);
		/* Send DISCONNECT */
		dl_send(fi, v5x_enc_disconnect(pstn->v5up, msg->data, msg->len));
		msgb_free(msg);
		break;
	case V5x_PSTN_LE_FE_disconnect_compl_req:
		/* change state to LE1 */
		// NOTE: The Table 31-32/G.964 is wrong at this point, see Figure B.3/G.964
		osmo_fsm_inst_state_chg(fi, V5x_LE_PTSN_S_LE1_NULL, 0, 0);
		/* stop all timers */
		stop_timer(fi);
		/* send DISCONNECT COMPLETE */
		dl_send(fi, v5x_enc_disconnect_compl(pstn->v5up, msg->data, msg->len));
		msgb_free(msg);
		break;
	case V5x_PSTN_LE_MDU_CTRL_port_blocked:
		/* do several thing here */
		do_block(fi);
		break;
	case V5x_PSTN_LE_MDU_CTRL_port_unblocked:
		/* ignore */
		break;
	case V5x_PSTN_LE_MDU_CTRL_restart_req:
		/* send DISCONNECT COMPLETE */
		dl_send(fi, v5x_enc_disconnect_compl(pstn->v5up, NULL, 0));
		/* do several thing here */
		do_restart(fi);
		break;
	case V5x_PSTN_LE_MDU_CTRL_restart_compl_req:
		/* ignore */
		break;
	case V5x_PSTN_LE_TIMEOUT_T4:
		/* first or second timeout ? */
		if (pstn->timeout_count < 3) {
			/* start T4 */
			start_timer(fi, V5x_PSTN_LE_TIMEOUT_T4, pstn->timeout_count + 1);
			/* send STATUS ENQUIRY again */
			dl_send(fi, v5x_enc_status_enquiry(pstn->v5up));
		} else {
			/* do several thing here */
			do_disconnect_with_error(fi);
		}	
		break;
	default:
		OSMO_ASSERT(0);
	}
}

static void pstn_le4_path_active(struct osmo_fsm_inst *fi, uint32_t event, void *data)
{
	struct v5x_pstn_proto *pstn = fi->priv;
	struct msgb *msg = data;
	const struct tlv_parsed *tp = data;
	uint8_t cause, seq_nr, unacked, acked;

	switch (event) {
	case V5x_PSTN_LE_ESTABLISH:
		/* do several thing here */
		do_status_enquiry(fi);
		break;
	case V5x_PSTN_LE_DISCONNECT:
		/* send DISCONNECT COMPLETE */
		dl_send(fi, v5x_enc_disconnect_compl(pstn->v5up, NULL, 0));
		/* do several thing here */
		do_disconnect_complete(fi, tp);
		break;
	case V5x_PSTN_LE_DISCONNECT_COMPL:
		/* send FE-disconnect_complete_indication */
		rcv_fe(fi, FE_disconnect_compl_ind, NULL);
		/* do several thing here */
		do_disconnect_complete(fi, tp);
		break;
	case V5x_PSTN_LE_ESTABLISH_ACK:
		/* start T4 */
		start_timer(fi, V5x_PSTN_LE_TIMEOUT_T4, 1);
		/* send STATUS ENQUIRY */
		dl_send(fi, v5x_enc_status_enquiry(pstn->v5up));
		break;
	case V5x_PSTN_LE_SIGNAL:
		/* get sequence number and check if msg is in sequence */
		seq_nr = *TLVP_VAL(tp, V5X_CTRL_IEI_SEQUENCE_NR) & 0x7f;
		if (pstn->S_r == seq_nr) {
			LOGPFSML(fi, LOGL_DEBUG, "Received expected 'receive' sequence number: S(R)=%d == M(R)=%d\n",
				 pstn->S_r, seq_nr);
			/* start Tr, if not pending */
			if (!osmo_timer_pending(&pstn->timer_Tr))
				start_timer_Tr(pstn);
			/* increment receive sequence number */
			pstn->S_r = (pstn->S_r + 1) & 127;
			/* send FE-signal_indication */
			rcv_fe(fi, FE_line_signal_ind, tp);
		} else {
			LOGPFSML(fi, LOGL_ERROR, "Invalid 'receive' sequence number: S(R)=%d != M(R)=%d\n",
				 pstn->S_r, seq_nr);
			/* send FE-signal_indication */
			rcv_fe(fi, FE_line_signal_ind, tp);
			/* do several thing here */
			do_disconnect_with_error(fi);
		}
		break;
	case V5x_PSTN_LE_SIGNAL_ACK:
		seq_nr = *TLVP_VAL(tp, V5X_CTRL_IEI_SEQUENCE_NR) & 0x7f;
		unacked = (pstn->S_s - pstn->S_a) & 127;
		acked = (pstn->S_s - seq_nr) & 127;
		if (acked <= unacked) {
			LOGPFSML(fi, LOGL_DEBUG, "Received expected 'transmit' sequence number: M(R)=%d is inside "
				 "S(A)=%d...S(S)=%d range\n", seq_nr, pstn->S_a, pstn->S_s);
			LOGPFSML(fi, LOGL_DEBUG, "We had %d unacked messages, now we have %d acked messages.\n", unacked, acked);
			/* update acknowledge sequence number */
			pstn->S_a = seq_nr;
			if (pstn->S_a == pstn->S_s) {
				LOGPFSML(fi, LOGL_DEBUG, "No more outstanding message, so we don't need Tt anymore.\n");
				/* stop Tt */
				stop_timer_Tt(pstn);
			} else {
				LOGPFSML(fi, LOGL_DEBUG, "There are still outstanding message, we still need Tt.\n");
				/* start Tt */
				start_timer_Tt(pstn);
			}
		} else {
			LOGPFSML(fi, LOGL_ERROR, "Invalid 'transmit' sequence number: M(R)=%d not inside "
				 "S(A)=%d...S(S)=%d range\n", seq_nr, pstn->S_a, pstn->S_s);
			/* do several thing here */
			do_disconnect_with_error(fi);
		}
		break;
	case V5x_PSTN_LE_STATUS:
		cause = *TLVP_VAL(tp, V5X_CTRL_IEI_CAUSE) & 0x7f;
		if (cause == 0) {
			/* stop T4 */
			stop_timer(fi);
		} else {
			/* do several thing here */
			do_disconnect_with_error(fi);
		}
		break;
	case V5x_PSTN_LE_FE_line_signal_req:
		/* if the maximum number of outstanding sequence numbers is not exceeded (127) */
		if (((pstn->S_s + 1) & 127) != pstn->S_a) {
			/* start Tt, if not pending: This is wrong in the state tables, but look at 13.5.5.2.2! */
			if (!osmo_timer_pending(&pstn->timer_Tt))
				start_timer_Tt(pstn);
			/* store SIGNAL message */
			if (pstn->tx_msg)
				msgb_free(pstn->tx_msg);
			pstn->tx_msg = msgb_copy(msg, NULL);
			/* send SIGNAL */
			dl_send(fi, v5x_enc_signal(pstn->v5up, pstn->S_s, msg->data, msg->len));
			msgb_free(msg);
			/* increment send sequence number */
			pstn->S_s = (pstn->S_s + 1) & 127;
		} else {
			/* send SIGNAL */
			dl_send(fi, v5x_enc_signal(pstn->v5up, pstn->S_s, msg->data, msg->len));
			msgb_free(msg);
			/* do several thing here */
			do_disconnect_with_error(fi);
		}
		break;
	case V5x_PSTN_LE_FE_protocol_param_req:
		/* if the maximum number of outstanding sequence numbers is not exceeded (127) */
		if (((pstn->S_s + 1) & 127) != pstn->S_a) {
			/* start Tt */
			start_timer_Tt(pstn);
			/* send SIGNAL */
			dl_send(fi, v5x_enc_protocol_param(pstn->v5up, pstn->S_s, msg->data, msg->len));
			msgb_free(msg);
			/* increment send sequence number */
			pstn->S_s = (pstn->S_s + 1) & 127;
		} else {
			/* send SIGNAL */
			dl_send(fi, v5x_enc_protocol_param(pstn->v5up, pstn->S_s, msg->data, msg->len));
			msgb_free(msg);
			/* do several thing here */
			do_disconnect_with_error(fi);
		}
		break;
	case V5x_PSTN_LE_FE_disconnect_req:
		/* change state to LE5 */
		osmo_fsm_inst_state_chg(fi, V5x_LE_PTSN_S_LE5_PATH_DICONNECT_REQ, 0, 0);
		/* stop all timers */
		stop_timer(fi);
		/* start T3 */
		start_timer(fi, V5x_PSTN_LE_TIMEOUT_T3, 2);
		/* store DISCONNECT message */
		if (pstn->tx_msg)
			msgb_free(pstn->tx_msg);
		pstn->tx_msg = msgb_copy(msg, NULL);
		/* Send DISCONNECT */
		dl_send(fi, v5x_enc_disconnect(pstn->v5up, msg->data, msg->len));
		msgb_free(msg);
		break;
	case V5x_PSTN_LE_FE_disconnect_compl_req:
		msgb_free(msg);
		/* ignore */
		break;
	case V5x_PSTN_LE_MDU_CTRL_port_blocked:
		/* do several thing here */
		do_block(fi);
		break;
	case V5x_PSTN_LE_MDU_CTRL_port_unblocked:
		/* ignore */
		break;
	case V5x_PSTN_LE_MDU_CTRL_restart_req:
		/* send DISCONNECT COMPLETE */
		dl_send(fi, v5x_enc_disconnect_compl(pstn->v5up, NULL, 0));
		/* do several thing here */
		do_restart(fi);
		break;
	case V5x_PSTN_LE_MDU_CTRL_restart_compl_req:
		/* ignore */
		break;
	case V5x_PSTN_LE_TIMEOUT_T4:
		/* first or second timeout ? */
		if (pstn->timeout_count < 3) {
			/* start T4 */
			start_timer(fi, V5x_PSTN_LE_TIMEOUT_T4, pstn->timeout_count + 1);
			/* send STATUS ENQUIRY again */
			dl_send(fi, v5x_enc_status_enquiry(pstn->v5up));
		} else {
			/* do several thing here */
			do_disconnect_with_error(fi);
		}	
		break;
	case V5x_PSTN_LE_TIMEOUT_Tr:
		/* send SIGNAL ACK */
		LOGPFSML(fi, LOGL_DEBUG, "Sending recent 'receive' sequence number: S(R)=%d as acknowledge.\n",
			 pstn->S_r);
		dl_send(fi, v5x_enc_signal_ack(pstn->v5up, pstn->S_r));
		break;
	case V5x_PSTN_LE_TIMEOUT_Tt:
		/* do several thing here */
		LOGPFSML(fi, LOGL_ERROR, "Aborting, because of missing acknowledge of outstanding 'transmit' sequence number: S(A)=%d...S(S)=%d\n", pstn->S_a, pstn->S_s);
		do_disconnect_with_error(fi);
		break;
	default:
		OSMO_ASSERT(0);
	}
}

static void pstn_le5_path_disconnect_req(struct osmo_fsm_inst *fi, uint32_t event, void *data)
{
	struct v5x_pstn_proto *pstn = fi->priv;
	struct msgb *msg = data;
	const struct tlv_parsed *tp = data;

	switch (event) {
	case V5x_PSTN_LE_ESTABLISH:
		/* ignore */
		break;
	case V5x_PSTN_LE_DISCONNECT:
	case V5x_PSTN_LE_DISCONNECT_COMPL:
		/* stop T3 */
		stop_timer(fi);
		/* change state to LE1 */
		osmo_fsm_inst_state_chg(fi, V5x_LE_PTSN_S_LE1_NULL, 0, 0);
		/* send FE-disconnect_complete_indication */
		rcv_fe(fi, FE_disconnect_compl_ind, tp);
		break;
	case V5x_PSTN_LE_ESTABLISH_ACK:
		/* ignore */
		break;
	case V5x_PSTN_LE_SIGNAL:
		/* ignore */
		break;
	case V5x_PSTN_LE_SIGNAL_ACK:
		/* ignore */
		break;
	case V5x_PSTN_LE_STATUS:
		/* ignore */
		break;
	case V5x_PSTN_LE_FE_line_signal_req:
		msgb_free(msg);
		/* ignore */
		break;
	case V5x_PSTN_LE_FE_protocol_param_req:
		msgb_free(msg);
		/* ignore */
		break;
	case V5x_PSTN_LE_FE_disconnect_compl_req:
		msgb_free(msg);
		/* ignore */
		break;
	case V5x_PSTN_LE_MDU_CTRL_port_blocked:
		/* do several thing here */
		do_block(fi);
		break;
	case V5x_PSTN_LE_MDU_CTRL_port_unblocked:
		/* ignore */
		break;
	case V5x_PSTN_LE_MDU_CTRL_restart_req:
		/* send DISCONNECT COMPLETE */
		dl_send(fi, v5x_enc_disconnect_compl(pstn->v5up, NULL, 0));
		/* do several thing here */
		do_restart(fi);
		break;
	case V5x_PSTN_LE_MDU_CTRL_restart_compl_req:
		/* ignore */
		break;
	case V5x_PSTN_LE_TIMEOUT_T3:
		/* send DISCONNECT again */
		if (pstn->tx_msg)
			dl_send(fi, v5x_enc_disconnect(pstn->v5up, pstn->tx_msg->data,
						pstn->tx_msg->len));
		else
			dl_send(fi, v5x_enc_disconnect(pstn->v5up, NULL, 0));
		/* start T3 */
		start_timer(fi, V5x_PSTN_LE_TIMEOUT_T3, pstn->timeout_count + 1);
		/* third timeout ? */
		if (pstn->timeout_count > 3) {
			/* send MDU-error_indication */
			rcv_mdu(fi, MDU_error_ind);
		}
		break;
	default:
		OSMO_ASSERT(0);
	}
}

static void pstn_le6_port_blocked(struct osmo_fsm_inst *fi, uint32_t event, void *data)
{
	struct v5x_pstn_proto *pstn = fi->priv;
	struct msgb *msg = data;

	switch (event) {
	case V5x_PSTN_LE_FE_establish_req:
		msgb_free(msg);
		/* ignore */
		break;
	case V5x_PSTN_LE_ESTABLISH:
	case V5x_PSTN_LE_DISCONNECT:
	case V5x_PSTN_LE_ESTABLISH_ACK:
	case V5x_PSTN_LE_SIGNAL:
	case V5x_PSTN_LE_SIGNAL_ACK:
		/* do several thing here */
		do_status_enquiry(fi);
		break;
	case V5x_PSTN_LE_DISCONNECT_COMPL:
		/* ignore */
		break;
	case V5x_PSTN_LE_FE_establish_ack_req:
		msgb_free(msg);
		/* ignore */
		break;
	case V5x_PSTN_LE_STATUS:
		break;
	case V5x_PSTN_LE_MDU_CTRL_port_blocked:
		/* ignore */
		break;
	case V5x_PSTN_LE_MDU_CTRL_port_unblocked:
		/* change state to LE1 */
		osmo_fsm_inst_state_chg(fi, V5x_LE_PTSN_S_LE1_NULL, 0, 0);
		break;
	case V5x_PSTN_LE_MDU_CTRL_restart_req:
		/* send MDU-CTRL (restart ack) */
		rcv_mdu(fi, MDU_CTRL_port_restart_ack);
		break;
	case V5x_PSTN_LE_MDU_CTRL_restart_compl_req:
		/* ignore */
		break;
	case V5x_PSTN_LE_TIMEOUT_T4:
		/* first or second timeout ? */
		if (pstn->timeout_count < 3) {
			/* start T4 */
			start_timer(fi, V5x_PSTN_LE_TIMEOUT_T4, pstn->timeout_count + 1);
			/* send STATUS ENQUIRY again */
			dl_send(fi, v5x_enc_status_enquiry(pstn->v5up));
		} else {
			/* send MDU-error_indication */
			rcv_mdu(fi, MDU_error_ind);
		}	
		break;
	default:
		OSMO_ASSERT(0);
	}
}

/* Table 3/G.964 Primitives, messages and timers used in the LE(PSTN) FSM */
static const struct osmo_fsm_state v5x_le_pstn_fsm_states[] = {
	[V5x_LE_PTSN_S_LE0_OUT_OF_SERVICE] = {
		.name = "Out of service (LE0)",
		.in_event_mask = S(V5x_PSTN_LE_FE_establish_req) |
				 S(V5x_PSTN_LE_ESTABLISH) |
				 S(V5x_PSTN_LE_DISCONNECT) |
				 S(V5x_PSTN_LE_DISCONNECT_COMPL) |
				 S(V5x_PSTN_LE_FE_establish_ack_req) |
				 S(V5x_PSTN_LE_ESTABLISH_ACK) |
				 S(V5x_PSTN_LE_SIGNAL) |
				 S(V5x_PSTN_LE_SIGNAL_ACK) |
				 S(V5x_PSTN_LE_STATUS) |
				 S(V5x_PSTN_LE_FE_protocol_param_req) |
				 S(V5x_PSTN_LE_FE_disconnect_req) |
				 S(V5x_PSTN_LE_MDU_CTRL_port_blocked) |
				 S(V5x_PSTN_LE_MDU_CTRL_port_unblocked) |
				 S(V5x_PSTN_LE_MDU_CTRL_restart_req) |
				 S(V5x_PSTN_LE_MDU_CTRL_restart_compl_req) |
				 S(V5x_PSTN_LE_TIMEOUT_T4),
		.out_state_mask = S(V5x_LE_PTSN_S_LE1_NULL) |
				  S(V5x_LE_PTSN_S_LE6_PORT_BLOCKED),
		.action = pstn_le0_out_of_service,
	},
	[V5x_LE_PTSN_S_LE1_NULL] = {
		.name = "Null (LE1)",
		.in_event_mask = S(V5x_PSTN_LE_FE_establish_req) |
				 S(V5x_PSTN_LE_ESTABLISH) |
				 S(V5x_PSTN_LE_DISCONNECT) |
				 S(V5x_PSTN_LE_ESTABLISH_ACK) |
				 S(V5x_PSTN_LE_SIGNAL) |
				 S(V5x_PSTN_LE_SIGNAL_ACK) |
				 S(V5x_PSTN_LE_STATUS) |
				 S(V5x_PSTN_LE_FE_protocol_param_req) |
				 S(V5x_PSTN_LE_MDU_CTRL_port_blocked) |
				 S(V5x_PSTN_LE_MDU_CTRL_port_unblocked) |
				 S(V5x_PSTN_LE_MDU_CTRL_restart_req) |
				 S(V5x_PSTN_LE_TIMEOUT_T4),
		.out_state_mask = S(V5x_LE_PTSN_S_LE0_OUT_OF_SERVICE) |
				  S(V5x_LE_PTSN_S_LE2_PATH_INITIATED_LE) |
				  S(V5x_LE_PTSN_S_LE3_PATH_INITIATED_AN) |
				  S(V5x_LE_PTSN_S_LE5_PATH_DICONNECT_REQ) |
				  S(V5x_LE_PTSN_S_LE6_PORT_BLOCKED),
		.action = pstn_le1_null,
	},
	[V5x_LE_PTSN_S_LE2_PATH_INITIATED_LE] = {
		.name = "Path initiated by LE (LE2)",
		.in_event_mask = S(V5x_PSTN_LE_ESTABLISH) |
				 S(V5x_PSTN_LE_DISCONNECT) |
				 S(V5x_PSTN_LE_DISCONNECT_COMPL) |
				 S(V5x_PSTN_LE_FE_establish_ack_req) |
				 S(V5x_PSTN_LE_ESTABLISH_ACK) |
				 S(V5x_PSTN_LE_SIGNAL) |
				 S(V5x_PSTN_LE_SIGNAL_ACK) |
				 S(V5x_PSTN_LE_STATUS) |
				 S(V5x_PSTN_LE_FE_protocol_param_req) |
				 S(V5x_PSTN_LE_FE_disconnect_req) |
				 S(V5x_PSTN_LE_FE_disconnect_compl_req) |
				 S(V5x_PSTN_LE_MDU_CTRL_port_blocked) |
				 S(V5x_PSTN_LE_MDU_CTRL_port_unblocked) |
				 S(V5x_PSTN_LE_MDU_CTRL_restart_req) |
				 S(V5x_PSTN_LE_MDU_CTRL_restart_compl_req) |
				 S(V5x_PSTN_LE_TIMEOUT_T1) |
				 S(V5x_PSTN_LE_TIMEOUT_T4),
		.out_state_mask = S(V5x_LE_PTSN_S_LE0_OUT_OF_SERVICE) |
				  S(V5x_LE_PTSN_S_LE1_NULL) |
				  S(V5x_LE_PTSN_S_LE4_PATH_ACTIVE) |
				  S(V5x_LE_PTSN_S_LE5_PATH_DICONNECT_REQ) |
				  S(V5x_LE_PTSN_S_LE6_PORT_BLOCKED),
		.action = pstn_le2_path_initiated_le,
	},
	[V5x_LE_PTSN_S_LE3_PATH_INITIATED_AN] = {
		.name = "Path initiated by AN (LE3)",
		.in_event_mask = S(V5x_PSTN_LE_FE_establish_req) |
				 S(V5x_PSTN_LE_ESTABLISH) |
				 S(V5x_PSTN_LE_DISCONNECT) |
				 S(V5x_PSTN_LE_DISCONNECT_COMPL) |
				 S(V5x_PSTN_LE_FE_establish_ack_req) |
				 S(V5x_PSTN_LE_ESTABLISH_ACK) |
				 S(V5x_PSTN_LE_SIGNAL) |
				 S(V5x_PSTN_LE_SIGNAL_ACK) |
				 S(V5x_PSTN_LE_STATUS) |
				 S(V5x_PSTN_LE_FE_protocol_param_req) |
				 S(V5x_PSTN_LE_FE_disconnect_req) |
				 S(V5x_PSTN_LE_FE_disconnect_compl_req) |
				 S(V5x_PSTN_LE_MDU_CTRL_port_blocked) |
				 S(V5x_PSTN_LE_MDU_CTRL_port_unblocked) |
				 S(V5x_PSTN_LE_MDU_CTRL_restart_req) |
				 S(V5x_PSTN_LE_MDU_CTRL_restart_compl_req) |
				 S(V5x_PSTN_LE_TIMEOUT_T4),
		.out_state_mask = S(V5x_LE_PTSN_S_LE0_OUT_OF_SERVICE) |
				  S(V5x_LE_PTSN_S_LE1_NULL) |
				  S(V5x_LE_PTSN_S_LE2_PATH_INITIATED_LE) |
				  S(V5x_LE_PTSN_S_LE4_PATH_ACTIVE) |
				  S(V5x_LE_PTSN_S_LE5_PATH_DICONNECT_REQ) |
				  S(V5x_LE_PTSN_S_LE6_PORT_BLOCKED),
		.action = pstn_le3_path_initiated_an,
	},
	[V5x_LE_PTSN_S_LE4_PATH_ACTIVE] = {
		.name = "Path active (LE4)",
		.in_event_mask = S(V5x_PSTN_LE_ESTABLISH) |
				 S(V5x_PSTN_LE_DISCONNECT) |
				 S(V5x_PSTN_LE_DISCONNECT_COMPL) |
				 S(V5x_PSTN_LE_ESTABLISH_ACK) |
				 S(V5x_PSTN_LE_SIGNAL) |
				 S(V5x_PSTN_LE_SIGNAL_ACK) |
				 S(V5x_PSTN_LE_STATUS) |
				 S(V5x_PSTN_LE_FE_line_signal_req) |
				 S(V5x_PSTN_LE_FE_protocol_param_req) |
				 S(V5x_PSTN_LE_FE_disconnect_req) |
				 S(V5x_PSTN_LE_FE_disconnect_compl_req) |
				 S(V5x_PSTN_LE_MDU_CTRL_port_blocked) |
				 S(V5x_PSTN_LE_MDU_CTRL_port_unblocked) |
				 S(V5x_PSTN_LE_MDU_CTRL_restart_req) |
				 S(V5x_PSTN_LE_MDU_CTRL_restart_compl_req) |
				 S(V5x_PSTN_LE_TIMEOUT_Tr) |
				 S(V5x_PSTN_LE_TIMEOUT_Tt) |
				 S(V5x_PSTN_LE_TIMEOUT_T4),
		.out_state_mask = S(V5x_LE_PTSN_S_LE0_OUT_OF_SERVICE) |
				  S(V5x_LE_PTSN_S_LE1_NULL) |
				  S(V5x_LE_PTSN_S_LE5_PATH_DICONNECT_REQ) |
				  S(V5x_LE_PTSN_S_LE6_PORT_BLOCKED),
		.action = pstn_le4_path_active,
	},
	[V5x_LE_PTSN_S_LE5_PATH_DICONNECT_REQ] = {
		.name = "Path Disconnect request (LE5)",
		.in_event_mask = S(V5x_PSTN_LE_ESTABLISH) |
				 S(V5x_PSTN_LE_DISCONNECT) |
				 S(V5x_PSTN_LE_DISCONNECT_COMPL) |
				 S(V5x_PSTN_LE_ESTABLISH_ACK) |
				 S(V5x_PSTN_LE_SIGNAL) |
				 S(V5x_PSTN_LE_SIGNAL_ACK) |
				 S(V5x_PSTN_LE_STATUS) |
				 S(V5x_PSTN_LE_FE_line_signal_req) |
				 S(V5x_PSTN_LE_FE_protocol_param_req) |
				 S(V5x_PSTN_LE_FE_disconnect_compl_req) |
				 S(V5x_PSTN_LE_MDU_CTRL_port_blocked) |
				 S(V5x_PSTN_LE_MDU_CTRL_port_unblocked) |
				 S(V5x_PSTN_LE_MDU_CTRL_restart_req) |
				 S(V5x_PSTN_LE_MDU_CTRL_restart_compl_req) |
				 S(V5x_PSTN_LE_TIMEOUT_T3),
		.out_state_mask = S(V5x_LE_PTSN_S_LE1_NULL),
		.action = pstn_le5_path_disconnect_req,
	},
	[V5x_LE_PTSN_S_LE6_PORT_BLOCKED] = {
		.name = "Port blocked (LE6)",
		.in_event_mask = S(V5x_PSTN_LE_FE_establish_req) |
				 S(V5x_PSTN_LE_ESTABLISH) |
				 S(V5x_PSTN_LE_DISCONNECT) |
				 S(V5x_PSTN_LE_DISCONNECT_COMPL) |
				 S(V5x_PSTN_LE_FE_establish_ack_req) |
				 S(V5x_PSTN_LE_ESTABLISH_ACK) |
				 S(V5x_PSTN_LE_SIGNAL) |
				 S(V5x_PSTN_LE_SIGNAL_ACK) |
				 S(V5x_PSTN_LE_STATUS) |
				 S(V5x_PSTN_LE_MDU_CTRL_port_blocked) |
				 S(V5x_PSTN_LE_MDU_CTRL_port_unblocked) |
				 S(V5x_PSTN_LE_MDU_CTRL_restart_req) |
				 S(V5x_PSTN_LE_MDU_CTRL_restart_compl_req) |
				 S(V5x_PSTN_LE_TIMEOUT_T4),
		.out_state_mask = S(V5x_LE_PTSN_S_LE1_NULL),
		.action = pstn_le6_port_blocked,
	},
};

struct osmo_fsm v5x_le_pstn_fsm = {
	.name = "V5X_LE_PSTN",
	.states = v5x_le_pstn_fsm_states,
	.num_states = ARRAY_SIZE(v5x_le_pstn_fsm_states),
	.allstate_event_mask = 0,
	.allstate_action = NULL,
	.cleanup = NULL,
	.timer_cb = v5x_le_pstn_fsm_timer_cb,
	.log_subsys = DV5PSTN,
	.event_names = v5x_ctrl_le_port_fsm_event_names,
};

struct v5x_pstn_proto *v5x_le_pstn_create(struct v5x_user_port *v5up, uint16_t nr)
{
	struct v5x_pstn_proto *pstn;

	OSMO_ASSERT(v5up);

	pstn = talloc_zero(v5up, struct v5x_pstn_proto);
	if (!pstn)
		return NULL;
	pstn->v5up = v5up;

	pstn->fi = osmo_fsm_inst_alloc(&v5x_le_pstn_fsm, pstn, pstn, LOGL_DEBUG, NULL);
	if (!pstn->fi)
		NULL;
	osmo_fsm_inst_update_id_f(pstn->fi, "%d", nr);
	pstn->timer_Tr.data = pstn;
	pstn->timer_Tr.cb = timeout_Tr_cb;
	pstn->timer_Tt.data = pstn;
	pstn->timer_Tt.cb = timeout_Tt_cb;

	return pstn;
}

void v5x_le_pstn_destroy(struct v5x_pstn_proto *pstn)
{
	/* free pending message */
	if (pstn->tx_msg)
		msgb_free(pstn->tx_msg);

	if (pstn->fi) {
		stop_timer_Tr(pstn);
		stop_timer_Tt(pstn);
		osmo_fsm_inst_free(pstn->fi);
	}

	talloc_free(pstn);
}

const char *v5x_le_pstn_state_name(struct v5x_pstn_proto *pstn)
{
	return v5x_le_pstn_fsm_states[pstn->fi->state].name;
}

void v5x_le_pstn_init(void)
{
	int rc;

	rc = osmo_fsm_register(&v5x_le_pstn_fsm);
	OSMO_ASSERT(!rc);
	LOGP(DV5PSTN, LOGL_NOTICE, "Using V5x PSTN protocol\n");
}

/***********************************************************************
 * V5 Message receiving / decoding
 ***********************************************************************/

/* receive message from lower (DL) layer */
int v5x_le_pstn_dl_rcv(struct v5x_user_port *v5up, uint8_t msg_type, const struct tlv_parsed *tp)
{
	enum v5x_le_pstn_fsm_event event;

	switch (msg_type) {
	case V5X_CTRL_MSGT_ESTABLISH:
		event = V5x_PSTN_LE_ESTABLISH;
		break;
       	case V5X_CTRL_MSGT_ESTABLISH_ACK:
		event = V5x_PSTN_LE_ESTABLISH_ACK;
		break;
       	case V5X_CTRL_MSGT_SIGNAL:
		event = V5x_PSTN_LE_SIGNAL;
		break;
       	case V5X_CTRL_MSGT_SIGNAL_ACK:
		event = V5x_PSTN_LE_SIGNAL_ACK;
		break;
       	case V5X_CTRL_MSGT_DISCONNECT:
		event = V5x_PSTN_LE_DISCONNECT;
		break;
       	case V5X_CTRL_MSGT_DISCONNECT_COMPLETE:
		event = V5x_PSTN_LE_DISCONNECT_COMPL;
		break;
       	case V5X_CTRL_MSGT_STATUS:
		event = V5x_PSTN_LE_STATUS;
		break;
	default:
		LOGPFSML(v5up->port_fi, LOGL_NOTICE, "Invalid PSTN protocol message %d receied from AN.\n", msg_type);
		return -EINVAL;
	}

	osmo_fsm_inst_dispatch(v5up->pstn.proto->fi, event, (void *)tp);

	return 0;
}