/* hnb-gw specific code for RUA (Ranap User Adaption) */

/* (C) 2015 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 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/licenses/>.
 *
 */


#include <osmocom/core/msgb.h>
#include <osmocom/core/utils.h>
#include <osmocom/netif/stream.h>

#include <osmocom/sigtran/sccp_sap.h>
#include <osmocom/sigtran/sua.h>

#include <unistd.h>
#include <errno.h>
#include <string.h>

#include "asn1helpers.h"

#include <osmocom/iuh/hnbgw.h>
#include <osmocom/iuh/hnbgw_ranap.h>
#include <osmocom/rua/rua_common.h>
#include <osmocom/rua/rua_ies_defs.h>
#include <osmocom/iuh/context_map.h>

static int hnbgw_rua_tx(struct hnb_context *ctx, struct msgb *msg)
{
	if (!msg)
		return -EINVAL;

	msgb_sctp_ppid(msg) = IUH_PPI_RUA;
	osmo_stream_srv_send(ctx->conn, msg);

	return 0;
}

int rua_tx_udt(struct hnb_context *hnb, const uint8_t *data, unsigned int len)
{
	RUA_ConnectionlessTransfer_t out;
	RUA_ConnectionlessTransferIEs_t ies;
	struct msgb *msg;
	int rc;

	memset(&ies, 0, sizeof(ies));
	ies.ranaP_Message.buf = (uint8_t *) data;
	ies.ranaP_Message.size = len;

	/* FIXME: msgb_free(msg)? ownership not yet clear */

	memset(&out, 0, sizeof(out));
	rc = rua_encode_connectionlesstransferies(&out, &ies);
	if (rc < 0)
		return rc;

	msg = rua_generate_initiating_message(RUA_ProcedureCode_id_ConnectionlessTransfer,
					      RUA_Criticality_reject,
					      &asn_DEF_RUA_ConnectionlessTransfer,
					      &out);
	ASN_STRUCT_FREE_CONTENTS_ONLY(asn_DEF_RUA_ConnectionlessTransfer, &out);

	DEBUGP(DRUA, "transmitting RUA payload of %u bytes\n", msgb_length(msg));

	return hnbgw_rua_tx(hnb, msg);
}

int rua_tx_dt(struct hnb_context *hnb, int is_ps, uint32_t context_id,
	      const uint8_t *data, unsigned int len)
{
	RUA_DirectTransfer_t out;
	RUA_DirectTransferIEs_t ies;
	uint32_t ctxidbuf;
	struct msgb *msg;
	int rc;

	memset(&ies, 0, sizeof(ies));
	if (is_ps)
		ies.cN_DomainIndicator = RUA_CN_DomainIndicator_ps_domain;
	else
		ies.cN_DomainIndicator = RUA_CN_DomainIndicator_cs_domain;
	asn1_u24_to_bitstring(&ies.context_ID, &ctxidbuf, context_id);
	ies.ranaP_Message.buf = (uint8_t *) data;
	ies.ranaP_Message.size = len;

	/* FIXME: msgb_free(msg)? ownership not yet clear */

	memset(&out, 0, sizeof(out));
	rc = rua_encode_directtransferies(&out, &ies);
	if (rc < 0)
		return rc;

	msg = rua_generate_initiating_message(RUA_ProcedureCode_id_DirectTransfer,
					      RUA_Criticality_reject,
					      &asn_DEF_RUA_DirectTransfer,
					      &out);
	ASN_STRUCT_FREE_CONTENTS_ONLY(asn_DEF_RUA_DirectTransfer, &out);

	DEBUGP(DRUA, "transmitting RUA (cn=%s) payload of %u bytes\n",
		is_ps ? "ps" : "cs", msgb_length(msg));

	return hnbgw_rua_tx(hnb, msg);
}

int rua_tx_disc(struct hnb_context *hnb, int is_ps, uint32_t context_id,
	        const RUA_Cause_t *cause, const uint8_t *data, unsigned int len)
{
	RUA_Disconnect_t out;
	RUA_DisconnectIEs_t ies;
	struct msgb *msg;
	uint32_t ctxidbuf;
	int rc;

	memset(&ies, 0, sizeof(ies));
	if (is_ps)
		ies.cN_DomainIndicator = RUA_CN_DomainIndicator_ps_domain;
	else
		ies.cN_DomainIndicator = RUA_CN_DomainIndicator_cs_domain;
	asn1_u24_to_bitstring(&ies.context_ID, &ctxidbuf, context_id);
	memcpy(&ies.cause, cause, sizeof(ies.cause));
	if (data && len) {
		ies.presenceMask |= DISCONNECTIES_RUA_RANAP_MESSAGE_PRESENT;
		ies.ranaP_Message.buf = (uint8_t *) data;
		ies.ranaP_Message.size = len;
	}

	/* FIXME: msgb_free(msg)? ownership not yet clear */

	memset(&out, 0, sizeof(out));
	rc = rua_encode_disconnecties(&out, &ies);
	if (rc < 0)
		return rc;

	msg = rua_generate_initiating_message(RUA_ProcedureCode_id_Disconnect,
					      RUA_Criticality_reject,
					      &asn_DEF_RUA_Disconnect,
					      &out);
	ASN_STRUCT_FREE_CONTENTS_ONLY(asn_DEF_RUA_Disconnect, &out);

	DEBUGP(DRUA, "transmitting RUA (cn=%s) payload of %u bytes\n",
		is_ps ? "ps" : "cs", msgb_length(msg));


	return hnbgw_rua_tx(hnb, msg);
}


/* forward a RUA message to the SCCP User API to SCCP/SUA */
static int rua_to_scu(struct hnb_context *hnb, struct hnbgw_cnlink *cn,
		      enum osmo_scu_prim_type type,
		      uint32_t context_id, uint32_t cause,
		      const uint8_t *data, unsigned int len)
{
	struct msgb *msg = msgb_alloc(1500, "rua_to_sua");
	struct osmo_scu_prim *prim;
	struct hnbgw_context_map *map;
	int rc;

	if (!cn) {
		DEBUGP(DRUA, "CN=NULL, discarding message\n");
		return 0;
	}

	prim = (struct osmo_scu_prim *) msgb_put(msg, sizeof(*prim));
	osmo_prim_init(&prim->oph, SCCP_SAP_USER, type, PRIM_OP_REQUEST, msg);

	map = context_map_alloc_by_hnb(hnb, context_id, cn);

	/* add primitive header */
	switch (type) {
	case OSMO_SCU_PRIM_N_CONNECT:
		prim->u.connect.called_addr;
		prim->u.connect.calling_addr;
		prim->u.connect.sccp_class = 2;
		prim->u.connect.conn_id = map->scu_conn_id;
		break;
	case OSMO_SCU_PRIM_N_DATA:
		prim->u.data.conn_id = map->scu_conn_id;
		break;
	case OSMO_SCU_PRIM_N_DISCONNECT:
		prim->u.disconnect.conn_id = map->scu_conn_id;
		prim->u.disconnect.cause = cause;
		break;
	case OSMO_SCU_PRIM_N_UNITDATA:
		prim->u.unitdata.called_addr;
		prim->u.unitdata.calling_addr;
		break;
	default:
		return -EINVAL;
	}

	/* add optional data section, if needed */
	if (data && len) {
		msg->l2h = msgb_put(msg, len);
		memcpy(msg->l2h, data, len);
	}

	rc = osmo_sua_user_link_down(cn->sua_link, &prim->oph);

	return rc;
}

static uint32_t rua_to_scu_cause(RUA_Cause_t *in)
{
	/* FIXME: Implement this! */
#if 0
	switch (in->present) {
	case RUA_Cause_PR_NOTHING:
		break;
	case RUA_Cause_PR_radioNetwork:
		switch (in->choice.radioNetwork) {
		case RUA_CauseRadioNetwork_normal:
		case RUA_CauseRadioNetwork_connect_failed:
		case RUA_CauseRadioNetwork_network_release:
		case RUA_CauseRadioNetwork_unspecified:
		}
		break;
	case RUA_Cause_PR_transport:
		switch (in->choice.transport) {
		case RUA_CauseTransport_transport_resource_unavailable:
			break;
		case RUA_CauseTransport_unspecified:
			break;
		}
		break;
	case RUA_Cause_PR_protocol:
		switch (in->choice.protocol) {
		case RUA_CauseProtocol_transfer_syntax_error:
			break;
		case RUA_CauseProtocol_abstract_syntax_error_reject:
			break;
		case RUA_CauseProtocol_abstract_syntax_error_ignore_and_notify:
			break;
		case RUA_CauseProtocol_message_not_compatible_with_receiver_state:
			break;
		case RUA_CauseProtocol_semantic_error:
			break;
		case RUA_CauseProtocol_unspecified:
			break;
		case RUA_CauseProtocol_abstract_syntax_error_falsely_constructed_message:
			break;
		}
		break;
	case RUA_Cause_PR_misc:
		switch (in->choice.misc) {
		case RUA_CauseMisc_processing_overload:
			break;
		case RUA_CauseMisc_hardware_failure:
			break;
		case RUA_CauseMisc_o_and_m_intervention:
			break;
		case RUA_CauseMisc_unspecified:
			break;
		}
		break;
	default:
		break;
	}
#else
	return 0;
#endif

}

static int rua_rx_init_connect(struct msgb *msg, ANY_t *in)
{
	RUA_ConnectIEs_t ies;
	struct hnb_context *hnb = msg->dst;
	struct hnbgw_cnlink *cn;
	uint32_t context_id;
	int rc;

	rc = rua_decode_connecties(&ies, in);
	if (rc < 0)
		return rc;

	context_id = asn1bitstr_to_u24(&ies.context_ID);

	/* route to CS (MSC) or PS (SGSN) domain */
	switch (ies.cN_DomainIndicator) {
	case RUA_CN_DomainIndicator_cs_domain:
		cn = hnb->gw->cnlink_cs;
		break;
	case RUA_CN_DomainIndicator_ps_domain:
		cn = hnb->gw->cnlink_ps;
		break;
	default:
		LOGP(DRUA, LOGL_ERROR, "Unsupported Domain %u\n",
			ies.cN_DomainIndicator);
		rua_free_connecties(&ies);
		return -1;
	}

	DEBUGP(DRUA, "RUA Connect.req(ctx=0x%x, %s)\n", context_id,
		ies.establishment_Cause == RUA_Establishment_Cause_emergency_call
		? "emergency" : "normal");

	rc = rua_to_scu(hnb, cn, OSMO_SCU_PRIM_N_CONNECT,
			context_id, 0, ies.ranaP_Message.buf,
			ies.ranaP_Message.size);
	/* FIXME: what to do with the asn1c-allocated memory */
	rua_free_connecties(&ies);

	return rc;
}

static int rua_rx_init_disconnect(struct msgb *msg, ANY_t *in)
{
	RUA_DisconnectIEs_t ies;
	struct hnb_context *hnb = msg->dst;
	struct hnbgw_cnlink *cn;
	uint32_t context_id;
	uint32_t scu_cause;
	uint8_t *ranap_data = NULL;
	unsigned int ranap_len = 0;
	int rc;

	rc = rua_decode_disconnecties(&ies, in);
	if (rc < 0)
		return rc;

	context_id = asn1bitstr_to_u24(&ies.context_ID);
	scu_cause = rua_to_scu_cause(&ies.cause);

	DEBUGP(DRUA, "RUA Disconnect.req(ctx=0x%x,cause=%s)\n", context_id,
		rua_cause_str(&ies.cause));

	/* route to CS (MSC) or PS (SGSN) domain */
	switch (ies.cN_DomainIndicator) {
	case RUA_CN_DomainIndicator_cs_domain:
		cn = hnb->gw->cnlink_cs;
		break;
	case RUA_CN_DomainIndicator_ps_domain:
		cn = hnb->gw->cnlink_ps;
		break;
	default:
		LOGP(DRUA, LOGL_ERROR, "Invalid CN_DomainIndicator: %u\n",
		     ies.cN_DomainIndicator);
		rc = -1;
		goto error_free;
	}

	if (ies.presenceMask & DISCONNECTIES_RUA_RANAP_MESSAGE_PRESENT) {
		ranap_data = ies.ranaP_Message.buf;
		ranap_len = ies.ranaP_Message.size;
	}

	rc = rua_to_scu(hnb, cn, OSMO_SCU_PRIM_N_DISCONNECT,
			context_id, scu_cause, ranap_data, ranap_len);

error_free:
	/* FIXME: what to do with the asn1c-allocated memory */
	rua_free_disconnecties(&ies);

	return rc;
}

static int rua_rx_init_dt(struct msgb *msg, ANY_t *in)
{
	RUA_DirectTransferIEs_t ies;
	struct hnb_context *hnb = msg->dst;
	struct hnbgw_cnlink *cn;
	uint32_t context_id;
	int rc;

	rc = rua_decode_directtransferies(&ies, in);
	if (rc < 0)
		return rc;

	context_id = asn1bitstr_to_u24(&ies.context_ID);

	DEBUGP(DRUA, "RUA Data.req(ctx=0x%x)\n", context_id);

	/* route to CS (MSC) or PS (SGSN) domain */
	switch (ies.cN_DomainIndicator) {
	case RUA_CN_DomainIndicator_cs_domain:
		cn = hnb->gw->cnlink_cs;
		break;
	case RUA_CN_DomainIndicator_ps_domain:
		cn = hnb->gw->cnlink_ps;
		break;
	default:
		LOGP(DRUA, LOGL_ERROR, "Invalid CN_DomainIndicator: %u\n",
		     ies.cN_DomainIndicator);
		rc = -1;
		goto error_free;
	}

	rc = rua_to_scu(hnb, cn, OSMO_SCU_PRIM_N_DATA,
			context_id, 0, ies.ranaP_Message.buf,
			ies.ranaP_Message.size);

error_free:
	/* FIXME: what to do with the asn1c-allocated memory */
	rua_free_directtransferies(&ies);

	return rc;

}

static int rua_rx_init_udt(struct msgb *msg, ANY_t *in)
{
	RUA_ConnectionlessTransferIEs_t ies;
	RUA_CN_DomainIndicator_t domain;
	int rc;

	rc = rua_decode_connectionlesstransferies(&ies, in);
	if (rc < 0)
		return rc;

	DEBUGP(DRUA, "RUA UData.req()\n");

	/* according tot the spec, we can primarily receive Overload,
	 * Reset, Reset ACK, Error Indication, reset Resource, Reset
	 * Resurce Acknowledge as connecitonless RANAP.  There are some
	 * more messages regarding Information Transfer, Direct
	 * Information Transfer and Uplink Information Trnansfer that we
	 * can ignore.  In either case, it is RANAP that we need to
	 * decode... */
	rc = hnbgw_ranap_rx(msg, ies.ranaP_Message.buf, ies.ranaP_Message.size);
	rua_free_connectionlesstransferies(&ies);

	return rc;
}


static int rua_rx_init_err_ind(struct msgb *msg, ANY_t *in)
{
	RUA_ErrorIndicationIEs_t ies;
	int rc;

	rc = rua_decode_errorindicationies(&ies, in);
	if (rc < 0)
		return rc;

	LOGP(DRUA, LOGL_ERROR, "RUA UData.ErrorInd(%s)\n",
		rua_cause_str(&ies.cause));

	rua_free_errorindicationies(&ies);
	return rc;
}

static int rua_rx_initiating_msg(struct msgb *msg, RUA_InitiatingMessage_t *imsg)
{
	int rc;

	switch (imsg->procedureCode) {
	case RUA_ProcedureCode_id_Connect:
		rc = rua_rx_init_connect(msg, &imsg->value);
		break;
	case RUA_ProcedureCode_id_DirectTransfer:
		rc = rua_rx_init_dt(msg, &imsg->value);
		break;
	case RUA_ProcedureCode_id_Disconnect:
		rc = rua_rx_init_disconnect(msg, &imsg->value);
		break;
	case RUA_ProcedureCode_id_ConnectionlessTransfer:
		rc = rua_rx_init_udt(msg, &imsg->value);
		break;
	case RUA_ProcedureCode_id_ErrorIndication:
		rc = rua_rx_init_err_ind(msg, &imsg->value);
		break;
	case RUA_ProcedureCode_id_privateMessage:
		LOGP(DRUA, LOGL_NOTICE,
		     "Unhandled: RUA Initiating Msg: Private Msg\n");
		rc = 0;
		break;
	default:
		LOGP(DRUA, LOGL_NOTICE, "Unknown RUA Procedure %u\n",
		     imsg->procedureCode);
		rc = -1;
	}

	return rc;
}

static int rua_rx_successful_outcome_msg(struct msgb *msg, RUA_SuccessfulOutcome_t *in)
{
	/* FIXME */
	LOGP(DRUA, LOGL_NOTICE, "Unexpected RUA Sucessful Outcome\n");
	return -1;
}

static int rua_rx_unsuccessful_outcome_msg(struct msgb *msg, RUA_UnsuccessfulOutcome_t *in)
{
	/* FIXME */
	LOGP(DRUA, LOGL_NOTICE, "Unexpected RUA Unsucessful Outcome\n");
	return -1;
}


static int _hnbgw_rua_rx(struct msgb *msg, RUA_RUA_PDU_t *pdu)
{
	int rc;

	/* it's a bit odd that we can't dispatch on procedure code, but
	 * that's not possible */
	switch (pdu->present) {
	case RUA_RUA_PDU_PR_initiatingMessage:
		rc = rua_rx_initiating_msg(msg, &pdu->choice.initiatingMessage);
		break;
	case RUA_RUA_PDU_PR_successfulOutcome:
		rc = rua_rx_successful_outcome_msg(msg, &pdu->choice.successfulOutcome);
		break;
	case RUA_RUA_PDU_PR_unsuccessfulOutcome:
		rc = rua_rx_unsuccessful_outcome_msg(msg, &pdu->choice.unsuccessfulOutcome);
		break;
	default:
		LOGP(DRUA, LOGL_NOTICE, "Unknown RUA presence %u\n", pdu->present);
		rc = -1;
	}

	return rc;
}

int hnbgw_rua_rx(struct hnb_context *hnb, struct msgb *msg)
{
	RUA_RUA_PDU_t _pdu, *pdu = &_pdu;
	asn_dec_rval_t dec_ret;
	int rc;

	/* decode and handle to _hnbgw_hnbap_rx() */

	memset(pdu, 0, sizeof(*pdu));
	dec_ret = aper_decode(NULL, &asn_DEF_RUA_RUA_PDU, (void **) &pdu,
			      msg->data, msgb_length(msg), 0, 0);
	if (dec_ret.code != RC_OK) {
		LOGP(DRUA, LOGL_ERROR, "Error in ASN.1 decode\n");
		return -1;
	}

	rc = _hnbgw_rua_rx(msg, pdu);

	return rc;
}


int hnbgw_rua_init(void)
{
	return 0;
}