library/BSSAP_LE_Emulation.ttcn

module BSSAP_LE_Emulation {

/* BSSAP_LE Emulation, runs on top of BSSAP_LE_CodecPort.  It multiplexes/demultiplexes
 * the individual connections, so there can be separate TTCN-3 components handling
 * each of the connections.
 *
 * The BSSAP_LE_Emulation.main() function processes SCCP primitives from the SCCP
 * stack via the BSSAP_CodecPort, and dispatches them to the per-connection components.
 *
 * Outbound BSSAP/SCCP connections are initiated by sending a BSSAP_LE_Conn_Req primitive
 * to the component running the BSSAP_LE_Emulation.main() function.
 *
 * For each new inbound connections, the BssapLeOps.create_cb() is called.  It can create
 * or resolve a TTCN-3 component, and returns a component reference to which that inbound
 * connection is routed/dispatched.
 *
 * If a pre-existing component wants to register to handle a future inbound connection, it can
 * do so by registering an "expect" with the expected Layer 3 (DTAP) payload.  This is e.g. useful
 * if you are simulating BTS + MSC, and first trigger a connection from BTS/RSL side in a
 * component which then subsequently should also handle the MSC emulation.
 *
 * Inbound Unit Data messages (such as are dispatched to the BssapLeOps.unitdata_cb() callback,
 * which is registered with an argument to the main() function below.
 *
 * (C) 2017-2020 by Harald Welte <laforge@gnumonks.org>
 * All rights reserved.
 *
 * Released under the terms of GNU General Public License, Version 2 or
 * (at your option) any later version.
 */


import from General_Types all;
import from Osmocom_Types all;
import from SCCP_Emulation all;
import from SCCPasp_Types all;
import from IPA_Emulation all;
import from MobileL3_Types all;
import from Misc_Helpers all;

import from BSSAP_LE_Types all;
import from BSSAP_LE_CodecPort all;
import from BSSMAP_LE_Templates all;
import from BSSMAP_Templates all;
import from RAN_Emulation all;

/* General "base class" component definition, of which specific implementations
 * derive themselves by means of the "extends" feature */
type component BSSAP_LE_ConnHdlr {
	/* port towards MSC Emulator core / SCCP connection dispatchar */
	port BSSAP_LE_Conn_PT BSSAP_LE;
	/* procedure based port to register for incoming connections */
	port BSSAP_LE_PROC_PT BSSAP_LE_PROC;
}

/* Auxiliary primitive that can happen on the port between per-connection client and this dispatcher */
type enumerated BSSAP_LE_Conn_Prim {
	/* SCCP tell us that connection was released */
	CONN_PRIM_DISC_IND,
	/* we tell SCCP to release connection */
	CONN_PRIM_DISC_REQ,
	/* Connection confirmed indication */
	CONN_PRIM_CONF_IND
}

/* port between individual per-connection components and this dispatcher */
type port BSSAP_LE_Conn_PT message {
	inout
		PDU_BSSAP_LE,
		BSSAP_LE_N_UNITDATA_req,
		/* Client requests us to create SCCP Connection */
		BSSAP_LE_Conn_Req,
		/* direct DTAP messages from/to clients */
		PDU_DTAP_MO, PDU_DTAP_MT,
		PDU_DTAP_PS_MO, PDU_DTAP_PS_MT,
		/* misc indications / requests between SCCP and client */
		BSSAP_LE_Conn_Prim;
} with { extension "internal" };

type uint2_t N_Sd_Array[4];

/* represents a single BSSAP connection over SCCP */
type record ConnectionData {
	/* reference to the instance of the per-connection component */
	BSSAP_LE_ConnHdlr	comp_ref,
	integer			sccp_conn_id,
	/* array of N(SD) values for MO DTAP messages, indexed by discriminator */
	N_Sd_Array		n_sd
}

type record ImsiMapping {
	BSSAP_LE_ConnHdlr	comp_ref,
	hexstring		imsi optional,
	OCT4			tmsi
}

type component BSSAP_LE_Emulation_CT {
	/* SCCP ports on the bottom side, using ASP primitives */
	port BSSAP_LE_CODEC_PT BSSAP_LE;
	/* BSSAP port to the per-connection clients */
	port BSSAP_LE_Conn_PT CLIENT;

	/* use 16 as this is also the number of SCCP connections that SCCP_Emulation can handle */
	var ConnectionData ConnectionTable[16];

	/* pending expected incoming connections */
	var ExpectData ExpectTable[8];

	/* tables for mapping inbound unitdata (like paging) */
	var ImsiMapping ImsiTable[16];

	/* procedure based port to register for incoming connections */
	port BSSAP_LE_PROC_PT PROC;

	var charstring g_ran_id;
	var integer g_next_e1_ts := 1;
	var BssapLeOps g_ran_ops;
	var boolean g_reset_ack_ready := false;
};

private function f_conn_id_known(integer sccp_conn_id)
runs on BSSAP_LE_Emulation_CT return boolean {
	var integer i;
	for (i := 0; i < sizeof(ConnectionTable); i := i+1) {
		if (ConnectionTable[i].sccp_conn_id == sccp_conn_id){
			return true;
		}
	}
	return false;
}

private function f_comp_known(BSSAP_LE_ConnHdlr client)
runs on BSSAP_LE_Emulation_CT return boolean {
	var integer i;
	for (i := 0; i < sizeof(ConnectionTable); i := i+1) {
		if (ConnectionTable[i].comp_ref == client) {
			return true;
		}
	}
	return false;
}

/* resolve component reference by connection ID */
private function f_comp_by_conn_id(integer sccp_conn_id)
runs on BSSAP_LE_Emulation_CT return BSSAP_LE_ConnHdlr {
	var integer i;
	for (i := 0; i < sizeof(ConnectionTable); i := i+1) {
		if (ConnectionTable[i].sccp_conn_id == sccp_conn_id) {
			return ConnectionTable[i].comp_ref;
		}
	}
	setverdict(fail, "BSSAP-LE Connection table not found by SCCP Connection ID ", sccp_conn_id);
	mtc.stop;
}

/* resolve connection ID by component reference */
private function f_conn_id_by_comp(BSSAP_LE_ConnHdlr client)
runs on BSSAP_LE_Emulation_CT return integer {
	for (var integer i := 0; i < sizeof(ConnectionTable); i := i+1) {
		if (ConnectionTable[i].comp_ref == client) {
			return ConnectionTable[i].sccp_conn_id;
		}
	}
	setverdict(fail, "BSSAP-LE Connection table not found by component ", client);
	mtc.stop;
}

/* resolve ConnectionTable index component reference */
private function f_idx_by_comp(BSSAP_LE_ConnHdlr client)
runs on BSSAP_LE_Emulation_CT return integer {
	for (var integer i := 0; i < sizeof(ConnectionTable); i := i+1) {
		if (ConnectionTable[i].comp_ref == client) {
			return i;
		}
	}
	setverdict(fail, "BSSAP-LE Connection table not found by component ", client);
	mtc.stop;
}

private function f_gen_conn_id()
runs on BSSAP_LE_Emulation_CT return integer {
	var integer conn_id;

	do {
		conn_id := float2int(rnd()*SCCP_Emulation.tsp_max_ConnectionId);
	} while (f_conn_id_known(conn_id) == true);

	return conn_id;
}

private function f_conn_table_init()
runs on BSSAP_LE_Emulation_CT {
	for (var integer i := 0; i < sizeof(ConnectionTable); i := i+1) {
		ConnectionTable[i].comp_ref := null;
		ConnectionTable[i].sccp_conn_id := -1;
		ConnectionTable[i].n_sd := { 0, 0, 0, 0 };
	}
	for (var integer i := 0; i < sizeof(ImsiTable); i := i+1) {
		ImsiTable[i].comp_ref := null;
		ImsiTable[i].imsi := omit;
		ImsiTable[i].tmsi := 'FFFFFFFF'O;
	}
}

private function f_conn_table_add(BSSAP_LE_ConnHdlr comp_ref, integer sccp_conn_id)
runs on BSSAP_LE_Emulation_CT {
	for (var integer i := 0; i < sizeof(ConnectionTable); i := i+1) {
		if (ConnectionTable[i].sccp_conn_id == -1) {
			ConnectionTable[i].comp_ref := comp_ref;
			ConnectionTable[i].sccp_conn_id := sccp_conn_id;
			ConnectionTable[i].n_sd := { 0, 0, 0, 0 };
			log("Added conn table entry ", i, comp_ref, sccp_conn_id);
			return;
		}
	}
	testcase.stop("BSSAP-LE Connection table full!");
}

private function f_conn_table_del(integer sccp_conn_id)
runs on BSSAP_LE_Emulation_CT {
	for (var integer i := 0; i < sizeof(ConnectionTable); i := i+1) {
		if (ConnectionTable[i].sccp_conn_id == sccp_conn_id) {
			log("Deleted conn table entry ", i,
			    ConnectionTable[i].comp_ref, sccp_conn_id);
			ConnectionTable[i].sccp_conn_id := -1;
			ConnectionTable[i].comp_ref := null;
			return
		}
	}
	setverdict(fail, "BSSAP-LE Connection table attempt to delete non-existant ", sccp_conn_id);
	mtc.stop;
}

private function f_imsi_table_find(hexstring imsi, template OCT4 tmsi)
runs on BSSAP_LE_Emulation_CT return BSSAP_LE_ConnHdlr {
	for (var integer i := 0; i < sizeof(ImsiTable); i := i+1) {
		if (ImsiTable[i].imsi == imsi or
		    isvalue(tmsi) and match(ImsiTable[i].tmsi, tmsi)) {
			return ImsiTable[i].comp_ref;
		}
	}
	return null;
}

type record BSSAP_LE_Conn_Req {
	SCCP_PAR_Address	addr_peer,
	SCCP_PAR_Address	addr_own,
	PDU_BSSAP_LE		bssap
}
template BSSAP_LE_Conn_Req ts_BSSAP_LE_Conn_Req(SCCP_PAR_Address peer, SCCP_PAR_Address own, PDU_BSSAP_LE bssap) := {
	addr_peer := peer,
	addr_own := own,
	bssap := bssap
};

/* handle (optional) userData portion of various primitives and dispatch it to the client */
private function f_handle_userData(BSSAP_LE_ConnHdlr client, PDU_BSSAP_LE bssap)
runs on BSSAP_LE_Emulation_CT {
	/* decode + send decoded BSSAP to client */

	if (ischosen(bssap.pdu.dtap) and g_ran_ops.decode_dtap) {
		if (g_ran_ops.role_ms) {
			/* we are the MS, so any message to us must be MT */
			var PDU_DTAP_MT mt := {
				dlci := bssap.dlci,
				dtap := dec_PDU_ML3_NW_MS(bssap.pdu.dtap)
			};
			CLIENT.send(mt) to client;
		} else {
			/* we are the Network, so any message to us must be MO */
			var PDU_DTAP_MO mo := {
				dlci := bssap.dlci,
				dtap := dec_PDU_ML3_MS_NW(bssap.pdu.dtap)
			};
			CLIENT.send(mo) to client;
		}
	} else {
		CLIENT.send(bssap) to client;
	}
}

/* call-back type, to be provided by specific implementation; called when new SCCP connection
 * arrives */
type function BssmapLeCreateCallback(BSSAP_LE_N_CONNECT_ind conn_ind, charstring id)
runs on BSSAP_LE_Emulation_CT return BSSAP_LE_ConnHdlr;

type function BssmapLeUnitdataCallback(PDU_BSSAP_LE bssap)
runs on BSSAP_LE_Emulation_CT return template PDU_BSSAP_LE;

/* handle common Unitdata such as Paging */
private function CommonBssmapUnitdataCallback(PDU_BSSAP_LE bssap)
runs on BSSAP_LE_Emulation_CT return template PDU_BSSAP_LE {
	if (match(bssap, tr_BSSMAP_LE_Paging)) {
		var BSSAP_LE_ConnHdlr client := null;
		client := f_imsi_table_find(bssap.pdu.bssmap.paging.iMSI.digits,
					   bssap.pdu.bssmap.paging.tMSI.tmsiOctets);
		if (client != null) {
			log("CommonBssmapUnitdataCallback: IMSI/TMSI found in table, dispatching to ",
				client);
			CLIENT.send(bssap) to client;
			return omit;
		}
		log("CommonBssmapUnitdataCallback: IMSI/TMSI not found in table");
	} else {
		log("CommonBssmapUnitdataCallback: Not a paging message");
	}
	/* ELSE: handle in user callback */
	return g_ran_ops.unitdata_cb.apply(bssap);
}

private function f_bssap_le_reset(SCCP_PAR_Address peer, SCCP_PAR_Address own) runs on BSSAP_LE_Emulation_CT {
	timer T := 5.0;

	BSSAP_LE.send(ts_BSSAP_LE_UNITDATA_req(peer, own, ts_BSSMAP_LE_Reset(GSM0808_CAUSE_RADIO_INTERFACE_MESSAGE_FAILURE)));
	T.start;
	alt {
	[] BSSAP_LE.receive(tr_BSSAP_LE_UNITDATA_ind(own, peer, tr_BSSMAP_LE_ResetAck)) {
		log("BSSMAP-LE: Received RESET-ACK in response to RESET, we're ready to go!");
		g_reset_ack_ready := true;
		}
	[] as_reset_ack();
	[] BSSAP_LE.receive { repeat };
	[] T.timeout {
		setverdict(fail, "BSSMAP-LE: Timeout waiting for RESET-ACK after sending RESET");
		mtc.stop;
		}
	}
}

private function f_bssap_l3_is_rr(PDU_BSSAP_LE bssap) return boolean {
	var template octetstring l3 := f_bssap_le_extract_l3(bssap);
	return f_L3_is_rr(l3);
}



type record BssapLeOps {
	BssmapLeCreateCallback create_cb optional,
	BssmapLeUnitdataCallback unitdata_cb optional,
	boolean decode_dtap,
	boolean role_ms,
	/* needed for performing BSSMAP RESET */
	SCCP_PAR_Address sccp_addr_local optional,
	SCCP_PAR_Address sccp_addr_peer optional
}

private altstep as_reset_ack() runs on BSSAP_LE_Emulation_CT {
	var BSSAP_LE_N_UNITDATA_ind ud_ind;
	[] BSSAP_LE.receive(tr_BSSAP_LE_UNITDATA_ind(?, ?, tr_BSSMAP_LE_Reset)) -> value ud_ind {
		log("BSSMAP-LE: Responding to inbound RESET with RESET-ACK");
		BSSAP_LE.send(ts_BSSAP_LE_UNITDATA_req(ud_ind.callingAddress, ud_ind.calledAddress,
			   ts_BSSMAP_LE_ResetAck));
		g_reset_ack_ready := true;
		repeat;
	}
}


private altstep as_main_bssap_le() runs on BSSAP_LE_Emulation_CT {
		var BSSAP_LE_N_UNITDATA_ind ud_ind;
		var BSSAP_LE_N_CONNECT_ind conn_ind;
		var BSSAP_LE_N_CONNECT_cfm conn_cfm;
		var BSSAP_LE_N_DATA_ind data_ind;
		var BSSAP_LE_N_DISCONNECT_ind disc_ind;
		var BSSAP_LE_Conn_Req creq;
		var PDU_BSSAP_LE bssap;
		var BSSAP_LE_N_UNITDATA_req bssap_ud;
		var BSSAP_LE_ConnHdlr vc_conn;
		var integer targetPointCode;
		var N_Sd_Array last_n_sd;

		/* SCCP -> Client: UNIT-DATA (connectionless SCCP) from a BSC */
		[] BSSAP_LE.receive(BSSAP_LE_N_UNITDATA_ind:?) -> value ud_ind {
			/* Connectionless Procedures like RESET */
			var template PDU_BSSAP_LE resp;
			resp := CommonBssmapUnitdataCallback(ud_ind.userData);
			if (isvalue(resp)) {
				BSSAP_LE.send(ts_BSSAP_LE_UNITDATA_req(ud_ind.callingAddress,
								ud_ind.calledAddress, resp));
			}
			}
		/* SCCP -> Client: new connection from BSC */
		[] BSSAP_LE.receive(BSSAP_LE_N_CONNECT_ind:?) -> value conn_ind {
			vc_conn := g_ran_ops.create_cb.apply(conn_ind, g_ran_id);
			/* store mapping between client components and SCCP connectionId */
			f_conn_table_add(vc_conn, conn_ind.connectionId);
			/* handle user payload */
			f_handle_userData(vc_conn, conn_ind.userData);
			/* confirm connection establishment */
			BSSAP_LE.send(ts_BSSAP_LE_CONNECT_res(conn_ind.connectionId, omit));
			}
		/* SCCP -> Client: connection-oriented data in existing connection */
		[] BSSAP_LE.receive(BSSAP_LE_N_DATA_ind:?) -> value data_ind {
			vc_conn := f_comp_by_conn_id(data_ind.connectionId);
			if (ispresent(data_ind.userData)) {
				f_handle_userData(vc_conn, data_ind.userData);
			}
			}
		/* SCCP -> Client: disconnect of an existing connection */
		[] BSSAP_LE.receive(BSSAP_LE_N_DISCONNECT_ind:?) -> value disc_ind {
			vc_conn := f_comp_by_conn_id(disc_ind.connectionId);
			if (ispresent(disc_ind.userData)) {
				f_handle_userData(vc_conn, disc_ind.userData);
			}
			/* notify client about termination */
			var BSSAP_LE_Conn_Prim prim := CONN_PRIM_DISC_IND;
			CLIENT.send(prim) to vc_conn;
			f_conn_table_del(disc_ind.connectionId);
			/* TOOD: return confirm to other side? */
			}
		/* SCCP -> Client: connection confirm for outbound connection */
		[] BSSAP_LE.receive(BSSAP_LE_N_CONNECT_cfm:?) -> value conn_cfm {
			vc_conn := f_comp_by_conn_id(conn_cfm.connectionId);
			var BSSAP_LE_Conn_Prim prim := CONN_PRIM_CONF_IND;
			CLIENT.send(prim) to vc_conn;
			/* handle user payload */
			if (ispresent(conn_cfm.userData)) {
				f_handle_userData(vc_conn, conn_cfm.userData);
			}
			}
		[] CLIENT.receive(PDU_BSSAP_LE:?) -> value bssap sender vc_conn {
			var integer conn_id := f_conn_id_by_comp(vc_conn);
			/* send it to dispatcher */
			BSSAP_LE.send(ts_BSSAP_LE_DATA_req(conn_id, bssap));
			}

		[] CLIENT.receive(BSSAP_LE_N_UNITDATA_req:?) -> value bssap_ud sender vc_conn {
			BSSAP_LE.send(bssap_ud);
			}

		/* Disconnect request client -> SCCP */
		[] CLIENT.receive(BSSAP_LE_Conn_Prim:CONN_PRIM_DISC_REQ) -> sender vc_conn {
			var integer conn_id := f_conn_id_by_comp(vc_conn);
			BSSAP_LE.send(ts_BSSAP_LE_DISC_req(conn_id, 0));
			f_conn_table_del(conn_id);
			}

		/* BSSAP from client -> SCCP */
		[] CLIENT.receive(BSSAP_LE_Conn_Req:?) -> value creq sender vc_conn {
			var integer conn_id;
			/* send to dispatcher */

			if (f_comp_known(vc_conn) == false) {
				/* unknown client, create new connection */
				conn_id := f_gen_conn_id();

				/* store mapping between client components and SCCP connectionId */
				f_conn_table_add(vc_conn, conn_id);

				BSSAP_LE.send(ts_BSSAP_LE_CONNECT_req(creq.addr_peer, creq.addr_own, conn_id,
								creq.bssap));
			} else {
				/* known client, send via existing connection */
				conn_id := f_conn_id_by_comp(vc_conn);
				BSSAP_LE.send(ts_BSSAP_LE_DATA_req(conn_id, creq.bssap));
			}

			/* InitialL3 contains RR (PAG RESP) or MM (CM SRV REQ), we must increment
			 * counter only on MM/CC/SS, but not on RR */
			if (g_ran_ops.role_ms and not f_bssap_l3_is_rr(creq.bssap)) {
				/* we have just sent the first MM message, increment the counter */
				var integer idx := f_idx_by_comp(vc_conn);
				ConnectionTable[idx].n_sd[0] := 1;
				log("patch: N(SD) for ConnIdx ", idx, " set to 1");
			}
			}

		[] PROC.getcall(BSSAP_LE_last_n_sd:{?,-}) -> param(vc_conn) {
			var integer idx := f_idx_by_comp(vc_conn);
			last_n_sd := ConnectionTable[idx].n_sd;
			PROC.reply(BSSAP_LE_last_n_sd:{vc_conn, last_n_sd}) to vc_conn;
			}

		[] PROC.getcall(BSSAP_LE_continue_after_n_sd:{?,?}) -> param(last_n_sd, vc_conn) {
			var integer idx := f_idx_by_comp(vc_conn);
			ConnectionTable[idx].n_sd := last_n_sd;
			PROC.reply(BSSAP_LE_continue_after_n_sd:{last_n_sd, vc_conn}) to vc_conn;
			}
}


/* send a raw (encoded) L3 message over given SCCP connection */
private function f_xmit_raw_l3(integer sccp_conn_id, OCT1 dlci, octetstring l3_enc) runs on BSSAP_LE_Emulation_CT
{
	var PDU_BSSAP_LE bssap;
	bssap := valueof(ts_BSSAP_LE_DTAP(l3_enc, dlci));
	BSSAP_LE.send(ts_BSSAP_LE_DATA_req(sccp_conn_id, bssap));
}

/* patch N(SD) into enc_l3, according to 24.007 11.2.3.2 */
private function f_ML3_patch_seq(inout ConnectionData cd, in PDU_ML3_MS_NW dtap, inout octetstring enc_l3) {
	var integer n_sd_idx := f_ML3_n_sd_idx(dtap);
	if (n_sd_idx < 0) {
		return;
	}
	var uint2_t seq_nr := f_next_n_sd(cd.n_sd, n_sd_idx);
	f_ML3_patch_seq_nr(seq_nr, enc_l3);
}

function main(BssapLeOps ops, charstring id) runs on BSSAP_LE_Emulation_CT {

	g_ran_id := id;
	g_ran_ops := ops;
	f_conn_table_init();
	f_expect_table_init();

	if (isvalue(ops.sccp_addr_peer) and isvalue(ops.sccp_addr_local)) {
		f_sleep(1.0);	/* HACK to wait for M3UA/ASP to be ACTIVE */
		f_bssap_le_reset(ops.sccp_addr_peer, ops.sccp_addr_local);
	}

	while (true) {
		var BSSAP_LE_ConnHdlr vc_conn;
		var PDU_DTAP_MO dtap_mo;
		var PDU_DTAP_MT dtap_mt;
		var BSSAP_LE_ConnHdlr vc_hdlr;
		var octetstring l3_info;
		var hexstring imsi;
		var OCT4 tmsi;
		var integer targetPointCode;

		alt {
		[] as_main_bssap_le();

		[g_ran_ops.role_ms] CLIENT.receive(PDU_DTAP_MO:?) -> value dtap_mo sender vc_conn {
			var integer idx := f_idx_by_comp(vc_conn);
			/* convert from decoded DTAP to encoded DTAP */
			var octetstring l3_enc := enc_PDU_ML3_MS_NW(dtap_mo.dtap);
			/* patch correct L3 send sequence number N(SD) into l3_enc */
			if (dtap_mo.skip_seq_patching == false) {
				f_ML3_patch_seq(ConnectionTable[idx], dtap_mo.dtap, l3_enc);
			}
			f_xmit_raw_l3(ConnectionTable[idx].sccp_conn_id, dtap_mo.dlci, l3_enc);
			}

		[not g_ran_ops.role_ms] CLIENT.receive(PDU_DTAP_MT:?) -> value dtap_mt sender vc_conn {
			var integer idx := f_idx_by_comp(vc_conn);
			/* convert from decoded DTAP to encoded DTAP */
			var octetstring l3_enc := enc_PDU_ML3_NW_MS(dtap_mt.dtap);
			f_xmit_raw_l3(ConnectionTable[idx].sccp_conn_id, dtap_mt.dlci, l3_enc);
			}

		[] PROC.getcall(BSSAP_LE_register:{?,?}) -> param(l3_info, vc_hdlr) {
			f_create_expect(l3_info, vc_hdlr);
			PROC.reply(BSSAP_LE_register:{l3_info, vc_hdlr}) to vc_hdlr;
			}

		[] PROC.getcall(BSSAP_LE_register_handoverRequest:{?,?}) -> param(targetPointCode, vc_hdlr) {
			f_create_expect(omit, vc_hdlr, targetPointCode);
			PROC.reply(BSSAP_LE_register_handoverRequest:{targetPointCode, vc_hdlr}) to vc_hdlr;
			}

		[] PROC.getcall(BSSAP_LE_register_imsi:{?,?,?}) -> param(imsi, tmsi, vc_hdlr) {
			f_create_imsi(imsi, tmsi, vc_hdlr);

			/* Wait for RESET-ACK if not received yet */
			if (not g_reset_ack_ready) {
				var integer wait_seconds := 10;
				timer T_reset_ack := 1.0;
				T_reset_ack.start;
				alt {
				[wait_seconds > 0] T_reset_ack.timeout {
					if (g_reset_ack_ready) {
						break;
					}
					wait_seconds := wait_seconds - 1;
					T_reset_ack.start;
					repeat;
					}

				[wait_seconds == 0] T_reset_ack.timeout {
					setverdict(fail, "BSSMAP-LE: Timeout waiting for RESET-ACK");
					mtc.stop;
					}
				}
			}

			PROC.reply(BSSAP_LE_register_imsi:{imsi, tmsi, vc_hdlr}) to vc_hdlr;
			}


		}
	}
}

/***********************************************************************
 * "Expect" Handling (mapping for expected incoming SCCP connections)
 ***********************************************************************/

/* data about an expected future incoming connection */
type record ExpectData {
	/* L3 payload based on which we can match it */
	octetstring l3_payload optional,
	integer handoverRequestPointCode optional,
	/* component reference for this connection */
	BSSAP_LE_ConnHdlr vc_conn
}

/* procedure based port to register for incoming connections */
signature BSSAP_LE_register(in octetstring l3, in BSSAP_LE_ConnHdlr hdlr);
signature BSSAP_LE_register_handoverRequest(in integer targetPointCode, in BSSAP_LE_ConnHdlr hdlr);

/* procedure based port to register for incoming IMSI/TMSI */
signature BSSAP_LE_register_imsi(in hexstring imsi, in OCT4 tmsi, in BSSAP_LE_ConnHdlr hdlr);

/* If DTAP happens across other channels (e.g. GSUP), provide manual advancing of the n_sd sequence number */
signature BSSAP_LE_last_n_sd(in BSSAP_LE_ConnHdlr hdlr, out N_Sd_Array last_n_sd);

/* Update conn's n_sd sequence nr after the connection was taken over from elsewhere */
signature BSSAP_LE_continue_after_n_sd(N_Sd_Array last_n_sd, in BSSAP_LE_ConnHdlr hdlr);

type port BSSAP_LE_PROC_PT procedure {
	inout BSSAP_LE_register, BSSAP_LE_register_imsi, BSSAP_LE_register_handoverRequest, BSSAP_LE_last_n_sd, BSSAP_LE_continue_after_n_sd;
} with { extension "internal" };

/* CreateCallback that can be used as create_cb and will use the expectation table */
function ExpectedCreateCallback(BSSAP_LE_N_CONNECT_ind conn_ind, charstring id)
runs on BSSAP_LE_Emulation_CT return BSSAP_LE_ConnHdlr {
	var BSSAP_LE_ConnHdlr ret := null;
	var octetstring l3_info;
	var integer i;

	if (ischosen(conn_ind.userData.pdu.bssmap.perf_loc_req)) {
		var BSSMAP_LE_PerfLocReq plr := conn_ind.userData.pdu.bssmap.perf_loc_req;
		if (not ispresent(plr.imsi)) {
			log("ExpectedCreateCallback: Cannot handle PerformLocReq without IMSI!");
			mtc.stop;
		}
		var hexstring imsi := plr.imsi.imsi.oddEvenInd_identity.imsi.digits;
		/* Find the component by the IMSI [usually] contained in this message */
		ret := f_imsi_table_find(imsi, omit);
		if (ret != null) {
			log("ExpectedCreateCallback: Found ConnHdlr ", ret, " for IMSI ", imsi);
			return ret;
		}
	} else if (ischosen(conn_ind.userData.pdu.bssmap.completeLayer3Information)) {
		l3_info := conn_ind.userData.pdu.bssmap.completeLayer3Information.layer3Information.layer3info;
		log("ExpectedCreateCallback completeLayer3Information");
	} else {
		setverdict(fail, "N-CONNECT.ind with L3 != { PerformLocReq | COMPLETE L3 }");
		mtc.stop;
	}

	for (i := 0; i < sizeof(ExpectTable); i:= i+1) {
		if (not ispresent(ExpectTable[i].l3_payload)) {
			continue;
		}
		if (l3_info == ExpectTable[i].l3_payload) {
			ret := ExpectTable[i].vc_conn;
			/* release this entry to be used again */
			ExpectTable[i].l3_payload := omit;
			ExpectTable[i].vc_conn := null;
			log("Found Expect[", i, "] for ", l3_info, " handled at ", ret);
			/* return the component reference */
			return ret;
		}
	}
	setverdict(fail, "Couldn't find Expect for incoming connection ", conn_ind);
	mtc.stop;
}


private function f_create_expect(template octetstring l3, BSSAP_LE_ConnHdlr hdlr,
				 template integer handoverRequestPointCode := omit)
runs on BSSAP_LE_Emulation_CT {
	var integer i;
	log("f_create_expect(l3 := ", l3, ", handoverRequest := ", handoverRequestPointCode);
	for (i := 0; i < sizeof(ExpectTable); i := i+1) {
		if (not ispresent(ExpectTable[i].l3_payload)
		    and not ispresent(ExpectTable[i].handoverRequestPointCode)) {
			if (ispresent(l3)) {
				ExpectTable[i].l3_payload := valueof(l3);
			}
			if (ispresent(handoverRequestPointCode)) {
				ExpectTable[i].handoverRequestPointCode := valueof(handoverRequestPointCode);
			}
			ExpectTable[i].vc_conn := hdlr;
			if (ispresent(handoverRequestPointCode)) {
				log("Created Expect[", i, "] for handoverRequest to be handled at ", hdlr);
			} else {
				log("Created Expect[", i, "] for ", l3, " to be handled at ", hdlr);
			}
			return;
		}
	}
	testcase.stop("No space left in ExpectTable");
}

private function f_create_imsi(hexstring imsi, OCT4 tmsi, BSSAP_LE_ConnHdlr hdlr)
runs on BSSAP_LE_Emulation_CT {
	for (var integer i := 0; i < sizeof(ImsiTable); i := i+1) {
		if (not ispresent(ImsiTable[i].imsi)) {
			ImsiTable[i].imsi := imsi;
			ImsiTable[i].tmsi := tmsi;
			ImsiTable[i].comp_ref := hdlr;
			log("Created IMSI[", i, "] for ", imsi, tmsi, " to be handled at ", hdlr);
			return;
		}
	}
	testcase.stop("No space left in ImsiTable");
}


private function f_expect_table_init()
runs on BSSAP_LE_Emulation_CT {
	for (var integer i := 0; i < sizeof(ExpectTable); i := i+1) {
		ExpectTable[i].l3_payload := omit;
		ExpectTable[i].handoverRequestPointCode := omit;
	}
}

/* helper function for clients to register their IMSI/TMSI */
/* FIXME: there is no TMSI in BSSMAP-LE */
function f_bssap_le_register_imsi(hexstring imsi, template (omit) OCT4 tmsi_or_omit)
runs on BSSAP_LE_ConnHdlr {
	var OCT4 tmsi;

	/* Resolve omit to a special reserved value */
	if (istemplatekind(tmsi_or_omit, "omit")) {
		tmsi := 'FFFFFFFF'O;
	} else {
		tmsi := valueof(tmsi_or_omit);
	}

	BSSAP_LE_PROC.call(BSSAP_LE_register_imsi:{imsi, tmsi, self}) {
		[] BSSAP_LE_PROC.getreply(BSSAP_LE_register_imsi:{?,?,?}) {};
	}
}


}