/* GPRS SM interfaces as per 3GPP TS 24.008, TS 24.007 */
/* (C) 2023 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
 * All Rights Reserved
 * Author: Pau Espin Pedrol <pespin@sysmocom.de>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation; either version 3 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/lienses/>.
 *
 */

#include <stdbool.h>
#include <string.h>
#include <stdint.h>
#include <errno.h>
#include <stdio.h>

#include <osmocom/core/msgb.h>
#include <osmocom/core/prim.h>
#include <osmocom/core/utils.h>
#include <osmocom/core/linuxlist.h>
#include <osmocom/core/talloc.h>
#include <osmocom/core/tun.h>
#include <osmocom/gsm/protocol/gsm_04_08_gprs.h>

#include <osmocom/gprs/gmm/gmm.h>
#include <osmocom/gprs/gmm/gmm_prim.h>
#include <osmocom/gprs/sndcp/sndcp.h>
#include <osmocom/gprs/sndcp/sndcp_prim.h>
#include <osmocom/gprs/sm/sm_prim.h>
#include <osmocom/gprs/sm/sm.h>
#include <osmocom/gprs/rlcmac/rlcmac_prim.h>

#include <osmocom/bb/common/settings.h>
#include <osmocom/bb/common/logging.h>
#include <osmocom/bb/common/apn.h>
#include <osmocom/bb/common/ms.h>
#include <osmocom/bb/modem/sm.h>


static int modem_sm_handle_pdp_act_cnf(struct osmocom_ms *ms, struct osmo_gprs_sm_prim *sm_prim)
{
	const char *pdu_name = osmo_gprs_sm_prim_name(sm_prim);
	struct osmobb_apn *apn = NULL, *apn_it;
	struct osmo_netdev *netdev;
	char buf_addr[INET6_ADDRSTRLEN];
	char buf_addr2[INET6_ADDRSTRLEN];
	int rc;

	llist_for_each_entry(apn_it, &ms->gprs.apn_list, list) {
		if (apn_it->fsm.fi->state == APN_ST_ACTIVATING) {
			apn = apn_it;
			break;
		}
	}

	if (!apn) {
		LOGP(DSM, LOGL_ERROR, "Rx %s but have no APN!\n", pdu_name);
		return -ENOENT;
	}

	if (!sm_prim->smreg.pdp_act_cnf.accepted) {
		LOGPAPN(LOGL_ERROR, apn, "Rx %s: Activate PDP failed! cause '%s'\n", pdu_name,
			get_value_string(gsm48_gsm_cause_names, sm_prim->smreg.pdp_act_cnf.rej.cause));
		osmo_fsm_inst_dispatch(apn->fsm.fi, APN_EV_RX_SM_ACT_PDP_CTX_REJ, NULL);
		/* TODO: maybe retry ? */
		return 0;
	}

	ms->subscr.gprs.ptmsi = sm_prim->smreg.pdp_act_cnf.acc.gmm.allocated_ptmsi;
	ms->gmmlayer.tlli = sm_prim->smreg.pdp_act_cnf.acc.gmm.allocated_tlli;

	apn->pdp.pdp_addr_ietf_type = sm_prim->smreg.pdp_act_cnf.acc.pdp_addr_ietf_type;

	netdev = osmo_tundev_get_netdev(apn->tun);
	switch (sm_prim->smreg.pdp_act_cnf.acc.pdp_addr_ietf_type) {
	case OSMO_GPRS_SM_PDP_ADDR_IETF_IPV4:
		LOGPAPN(LOGL_INFO, apn, "Rx %s: IPv4=%s\n", pdu_name,
			osmo_sockaddr_ntop(&sm_prim->smreg.pdp_act_cnf.acc.pdp_addr_v4.u.sa, buf_addr));
		memcpy(&apn->pdp.pdp_addr_v4, &sm_prim->smreg.pdp_act_cnf.acc.pdp_addr_v4, sizeof(struct osmo_sockaddr));
		rc = osmo_netdev_add_addr(netdev, &sm_prim->smreg.pdp_act_cnf.acc.pdp_addr_v4, 30);
		if (rc < 0) {
			LOGPAPN(LOGL_ERROR, apn, "Rx %s: Failed setting IPv4=%s\n", pdu_name,
				osmo_sockaddr_ntop(&sm_prim->smreg.pdp_act_cnf.acc.pdp_addr_v4.u.sa, buf_addr));
			return rc;
		}
		break;
	case OSMO_GPRS_SM_PDP_ADDR_IETF_IPV6:
		LOGPAPN(LOGL_INFO, apn, "Rx %s: IPv6=%s [FIXME: IPv6 not yet supported!]\n", pdu_name,
			osmo_sockaddr_ntop(&sm_prim->smreg.pdp_act_cnf.acc.pdp_addr_v6.u.sa, buf_addr));
		memcpy(&apn->pdp.pdp_addr_v6, &sm_prim->smreg.pdp_act_cnf.acc.pdp_addr_v6, sizeof(struct osmo_sockaddr));
		rc = osmo_netdev_add_addr(netdev, &sm_prim->smreg.pdp_act_cnf.acc.pdp_addr_v6, 64);
		if (rc < 0) {
			LOGPAPN(LOGL_ERROR, apn, "Rx %s: Failed setting IPv6=%s\n", pdu_name,
				osmo_sockaddr_ntop(&sm_prim->smreg.pdp_act_cnf.acc.pdp_addr_v6.u.sa, buf_addr));
			return rc;
		}
		break;
	case OSMO_GPRS_SM_PDP_ADDR_IETF_IPV4V6:
		LOGPAPN(LOGL_INFO, apn, "Rx %s: IPv4=%s IPv6=%s [FIXME: IPv6 not yet supported!]\n", pdu_name,
			osmo_sockaddr_ntop(&sm_prim->smreg.pdp_act_cnf.acc.pdp_addr_v4.u.sa, buf_addr),
			osmo_sockaddr_ntop(&sm_prim->smreg.pdp_act_cnf.acc.pdp_addr_v6.u.sa, buf_addr2));
		memcpy(&apn->pdp.pdp_addr_v4, &sm_prim->smreg.pdp_act_cnf.acc.pdp_addr_v4, sizeof(struct osmo_sockaddr));
		memcpy(&apn->pdp.pdp_addr_v6, &sm_prim->smreg.pdp_act_cnf.acc.pdp_addr_v6, sizeof(struct osmo_sockaddr));
		rc = osmo_netdev_add_addr(netdev, &sm_prim->smreg.pdp_act_cnf.acc.pdp_addr_v4, 30);
		if (rc < 0) {
			LOGPAPN(LOGL_ERROR, apn, "Rx %s: Failed setting IPv4=%s\n", pdu_name,
				osmo_sockaddr_ntop(&sm_prim->smreg.pdp_act_cnf.acc.pdp_addr_v4.u.sa, buf_addr));
			return rc;
		}
		rc = osmo_netdev_add_addr(netdev, &sm_prim->smreg.pdp_act_cnf.acc.pdp_addr_v6, 64);
		if (rc < 0) {
			LOGPAPN(LOGL_ERROR, apn, "Rx %s: Failed setting IPv6=%s\n", pdu_name,
				osmo_sockaddr_ntop(&sm_prim->smreg.pdp_act_cnf.acc.pdp_addr_v6.u.sa, buf_addr));
			return rc;
		}
		break;
	default:
		OSMO_ASSERT(0);
	}

	/* TODO: Handle PCO */
	/* TODO: Handle QoS */

	osmo_fsm_inst_dispatch(apn->fsm.fi, APN_EV_RX_SM_ACT_PDP_CTX_ACC, NULL);
	return rc;
}

static int modem_sm_prim_up_cb(struct osmo_gprs_sm_prim *sm_prim, void *user_data)
{
	const char *pdu_name = osmo_gprs_sm_prim_name(sm_prim);
	struct osmocom_ms *ms = user_data;
	int rc = 0;

	switch (sm_prim->oph.sap) {
	case OSMO_GPRS_SM_SAP_SMREG:
		switch (OSMO_PRIM_HDR(&sm_prim->oph)) {
		case OSMO_PRIM(OSMO_GPRS_SM_SMREG_PDP_ACTIVATE, PRIM_OP_CONFIRM):
			modem_sm_handle_pdp_act_cnf(ms, sm_prim);
			break;
		case OSMO_PRIM(OSMO_GPRS_SM_SMREG_PDP_ACTIVATE, PRIM_OP_INDICATION):
		case OSMO_PRIM(OSMO_GPRS_SM_SMREG_PDP_DEACTIVATE, PRIM_OP_CONFIRM):
		case OSMO_PRIM(OSMO_GPRS_SM_SMREG_PDP_DEACTIVATE, PRIM_OP_INDICATION):
		case OSMO_PRIM(OSMO_GPRS_SM_SMREG_PDP_MODIFY, PRIM_OP_CONFIRM):
		case OSMO_PRIM(OSMO_GPRS_SM_SMREG_PDP_MODIFY, PRIM_OP_INDICATION):
		case OSMO_PRIM(OSMO_GPRS_SM_SMREG_PDP_ACTIVATE_SEC, PRIM_OP_CONFIRM):
		default:
			LOGP(DSM, LOGL_ERROR, "%s(): Rx %s UNIMPLEMENTED\n", __func__, pdu_name);
			break;
		};
		break;
	default:
		LOGP(DSM, LOGL_ERROR, "%s(): Unexpected Rx %s\n", __func__, pdu_name);
		OSMO_ASSERT(0);
	}

	return rc;
}

int modem_sm_prim_sndcp_up_cb(struct osmo_gprs_sndcp_prim *sndcp_prim, void *user_data)
{
	const char *pdu_name = osmo_gprs_sndcp_prim_name(sndcp_prim);
	int rc;

	switch (sndcp_prim->oph.sap) {
	case OSMO_GPRS_SNDCP_SAP_SNSM:
		switch (OSMO_PRIM_HDR(&sndcp_prim->oph)) {
		case OSMO_PRIM(OSMO_GPRS_SNDCP_SNSM_ACTIVATE, PRIM_OP_INDICATION):
			LOGP(DSM, LOGL_INFO, "%s(): Rx %s\n", __func__, pdu_name);
			rc = osmo_gprs_sndcp_prim_dispatch_snsm(sndcp_prim);
			rc = 1; /* Tell SM that we take ownership of the prim. */
			break;
		default:
			LOGP(DSM, LOGL_ERROR, "%s(): Unexpected Rx %s\n", __func__, pdu_name);
			OSMO_ASSERT(0);
		}
		break;
	default:
		LOGP(DSM, LOGL_ERROR, "%s(): Unexpected Rx %s\n", __func__, pdu_name);
		OSMO_ASSERT(0);
	}
	return rc;
}

static int modem_sm_prim_down_cb(struct osmo_gprs_sm_prim *sm_prim, void *user_data)
{
	const char *pdu_name = osmo_gprs_sm_prim_name(sm_prim);
	int rc = 0;

	switch (sm_prim->oph.sap) {
	default:
		LOGP(DSM, LOGL_ERROR, "%s(): Unexpected Rx %s\n", __func__, pdu_name);
		OSMO_ASSERT(0);
	}

	return rc;
}

static int modem_sm_prim_gmm_down_cb(struct osmo_gprs_gmm_prim *gmm_prim, void *user_data)
{
	int rc;

	rc = osmo_gprs_gmm_prim_upper_down(gmm_prim);

	/* GMM took ownership of the message, tell SM layer to not free it: */
	rc = 1;
	return rc;
}

int modem_sm_init(struct osmocom_ms *ms)
{
	int rc;
	rc = osmo_gprs_sm_init(OSMO_GPRS_SM_LOCATION_MS);
	if (rc != 0)
		return rc;

	osmo_gprs_sm_set_log_cat(OSMO_GPRS_SM_LOGC_SM, DSM);

	osmo_gprs_sm_prim_set_up_cb(modem_sm_prim_up_cb, ms);
	osmo_gprs_sm_prim_set_sndcp_up_cb(modem_sm_prim_sndcp_up_cb, ms);
	osmo_gprs_sm_prim_set_down_cb(modem_sm_prim_down_cb, ms);
	osmo_gprs_sm_prim_set_gmm_down_cb(modem_sm_prim_gmm_down_cb, ms);

	return rc;
}

int modem_sm_smreg_pdp_act_req(const struct osmocom_ms *ms, const struct osmobb_apn *apn)
{
	struct osmo_gprs_sm_prim *sm_prim;
	const struct gsm_subscriber *subscr = &ms->subscr;
	enum osmo_gprs_sm_pdp_addr_ietf_type pdp_addr_ietf_type;
	struct osmo_sockaddr pdp_addr_any = {0};
	int rc;

	if (apn->cfg.apn_type_mask & APN_TYPE_IPv4v6) {
		pdp_addr_ietf_type = OSMO_GPRS_SM_PDP_ADDR_IETF_IPV4V6;
	} else if (apn->cfg.apn_type_mask & APN_TYPE_IPv4) {
		pdp_addr_ietf_type = OSMO_GPRS_SM_PDP_ADDR_IETF_IPV4;
	} else if (apn->cfg.apn_type_mask & APN_TYPE_IPv6) {
		pdp_addr_ietf_type = OSMO_GPRS_SM_PDP_ADDR_IETF_IPV6;
	} else {
		LOGP(DSM, LOGL_ERROR, "APN '%s' has no PDP address type set\n", apn->cfg.name);
		return -EINVAL;
	}

	sm_prim = osmo_gprs_sm_prim_alloc_smreg_pdp_act_req();
	sm_prim->smreg.pdp_act_req.nsapi = apn->pdp.nsapi;
	sm_prim->smreg.pdp_act_req.llc_sapi = apn->pdp.llc_sapi;
	sm_prim->smreg.pdp_act_req.pdp_addr_ietf_type = pdp_addr_ietf_type;
	sm_prim->smreg.pdp_act_req.pdp_addr_v4 = pdp_addr_any;
	sm_prim->smreg.pdp_act_req.pdp_addr_v6 = pdp_addr_any;
	memcpy(sm_prim->smreg.pdp_act_req.qos, apn->pdp.qos, apn->pdp.qos_len);
	sm_prim->smreg.pdp_act_req.qos_len = apn->pdp.qos_len;
	memcpy(sm_prim->smreg.pdp_act_req.pco, apn->pdp.pco, apn->pdp.pco_len);
	sm_prim->smreg.pdp_act_req.pco_len = apn->pdp.pco_len;
	OSMO_STRLCPY_ARRAY(sm_prim->smreg.pdp_act_req.apn, apn->cfg.name);
	sm_prim->smreg.pdp_act_req.gmm.ptmsi = subscr->gprs.ptmsi;
	sm_prim->smreg.pdp_act_req.gmm.ptmsi_sig = subscr->gprs.ptmsi;
	OSMO_STRLCPY_ARRAY(sm_prim->smreg.pdp_act_req.gmm.imsi, subscr->imsi);
	OSMO_STRLCPY_ARRAY(sm_prim->smreg.pdp_act_req.gmm.imei, ms->settings.imei);
	OSMO_STRLCPY_ARRAY(sm_prim->smreg.pdp_act_req.gmm.imeisv, ms->settings.imeisv);
	memcpy(&sm_prim->smreg.pdp_act_req.gmm.old_rai, &subscr->gprs.rai, sizeof(subscr->gprs.rai));

	rc = osmo_gprs_sm_prim_upper_down(sm_prim);
	if (rc < 0)
		LOGP(DSM, LOGL_ERROR, "Failed submitting SMREG-PDP_ACT_REQ.req\n");
	return rc;
}