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module MSC_ConnectionHandler {
/* (C) 2017-2019 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.
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
import from General_Types all;
import from Osmocom_Types all;
import from SCCPasp_Types all;
import from BSSAP_Types all;
import from BSSAP_CodecPort all;
import from RAN_Emulation all;
import from BSSMAP_Templates all;
import from MGCP_Types all;
import from MGCP_Templates all;
import from SDP_Types all;
type function void_fn_msc(charstring id) runs on MSC_ConnHdlr;
/* this component represents a single subscriber connection at the MSC.
* There is a 1:1 mapping between SCCP connections and RAN_ConnHdlr components.
* We inherit all component variables, ports, functions, ... from RAN_ConnHdlr */
type component MSC_ConnHdlr extends RAN_ConnHdlr {
/* SCCP Connecction Identifier for the underlying SCCP connection */
var integer g_sccp_conn_id;
var MSC_State g_state := MSC_STATE_NONE;
var MgcpEndpoint g_ep_name;
var MgcpCallId g_call_id;
var MgcpConnectionId g_mgcp_conn_id;
var MSC_TestHdlrParams g_pars;
}
type record MSC_TestHdlrParams {
integer connection_id,
integer e1_timeslot
};
/* helper function to create and connect a MSC_ConnHdlr component */
private function f_connect_handler(inout MSC_ConnHdlr vc_conn) runs on RAN_Emulation_CT {
/* connect client BSSAP port to BSSAP dispatcher */
connect(vc_conn:BSSAP, self:CLIENT);
}
private function f_msc_start_handler(void_fn_msc fn, charstring id, template (omit) MSC_TestHdlrParams pars := omit)
runs on RAN_Emulation_CT return MSC_ConnHdlr {
var MSC_ConnHdlr vc_conn;
vc_conn := MSC_ConnHdlr.create(id);
f_connect_handler(vc_conn);
vc_conn.start(f_handler_init(fn, id, pars));
return vc_conn;
}
/* first function inside ConnHdlr component; sets g_pars + starts function */
private function f_handler_init(void_fn_msc fn, charstring id, template (omit) MSC_TestHdlrParams pars := omit)
runs on MSC_ConnHdlr {
if (isvalue(pars)) {
g_pars := valueof(pars);
}
fn.apply(id);
}
/* Callback function from general BSSMAP_Emulation whenever a connectionless
* BSSMAP message arrives. Can retunr a PDU_BSSAP that should be sent in return */
private function UnitdataCallback(PDU_BSSAP bssap)
runs on RAN_Emulation_CT return template PDU_BSSAP {
var template PDU_BSSAP resp := omit;
if (match(bssap, tr_BSSMAP_Reset)) {
resp := ts_BSSMAP_ResetAck;
}
return resp;
}
/* Callback function from general BSSMAP_Emulation whenever a new incoming
* SCCP connection arrivces. Must create + start a new component */
private function CreateCallback_generic(void_fn_msc fn, BSSAP_N_CONNECT_ind conn_ind, charstring id)
runs on RAN_Emulation_CT return RAN_ConnHdlr {
var MSC_ConnHdlr vc_conn;
var MSC_TestHdlrParams pars;
pars.connection_id := conn_ind.connectionId;
pars.e1_timeslot := g_next_e1_ts;
/* Create a new RAN_ConnHdlr component */
vc_conn := f_msc_start_handler(fn, g_ran_id & "-Conn-" & int2str(conn_ind.connectionId), pars);
/* increment next E1 timeslot */
g_next_e1_ts := g_next_e1_ts + 1;
return vc_conn;
}
const RanOps MSC_RanOps := {
create_cb := omit,
unitdata_cb := refers(UnitdataCallback),
decode_dtap := false,
role_ms := false,
protocol := RAN_PROTOCOL_BSSAP,
transport := BSSAP_TRANSPORT_AoIP,
use_osmux := false,
bssap_reset_retries := 1,
sccp_addr_local := omit,
sccp_addr_peer := omit
}
type enumerated MSC_State {
MSC_STATE_NONE,
MSC_STATE_WAIT_ASS_COMPL,
MSC_STATE_WAIT_CRCX_ACK,
MSC_STATE_WAIT_MDCX_ACK,
MSC_STATE_WAIT_CLEAR_COMPL,
MSC_STATE_WAIT_DLCX_ACK
}
/* Callback function from general BSSMAP_Emulation whenever a new incoming
* SCCP connection arrivces. Must create + start a new component */
function CreateCallback_establish_fully(BSSAP_N_CONNECT_ind conn_ind, charstring id)
runs on RAN_Emulation_CT return RAN_ConnHdlr {
return CreateCallback_generic(refers(f_msc_establish_fully), conn_ind, id);
}
/* main function processing various incoming events */
function f_msc_establish_fully(charstring id) runs on MSC_ConnHdlr {
var MgcpResponse mgcp_rsp;
timer T := 5.0;
g_sccp_conn_id := g_pars.connection_id;
g_call_id := f_mgcp_alloc_call_id();
g_ep_name := hex2str(int2hex(g_pars.e1_timeslot, 1)) & "@mgw";
/* we just accepted an incoming SCCP connection, start guard timer */
T.start;
while (true) {
var PDU_BSSAP bssap;
alt {
/* new SCCP-level connection indication from BSC */
[g_state == MSC_STATE_NONE] BSSAP.receive(tr_BSSMAP_ComplL3) -> value bssap {
/* respond with ASSIGNMENT CMD */
g_state := MSC_STATE_WAIT_ASS_COMPL;
BSSAP.send(ts_BSSMAP_AssignmentReq(ts_BSSMAP_IE_CIC(0, g_pars.e1_timeslot)));
}
[g_state == MSC_STATE_WAIT_ASS_COMPL] BSSAP.receive(tr_BSSMAP_AssignmentComplete(?,*)) {
/* FIXME: Send MGCP CRCX */
g_state := MSC_STATE_WAIT_CRCX_ACK;
var MgcpTransId trans_id := f_mgcp_alloc_tid();
//template SDP_Message sdp := omit;
BSSAP.send(ts_CRCX(trans_id, g_ep_name, "recvonly", g_call_id)); //, sdp));
}
/*
[] BSSAP.receive(tr_BSSMAP_AssignmentFail) {
}
*/
/* receive CRCX ACK: transmit MDCX */
[g_state == MSC_STATE_WAIT_CRCX_ACK] BSSAP.receive(tr_CRCX_ACK) -> value mgcp_rsp {
/* extract connection ID */
g_mgcp_conn_id := f_MgcpResp_extract_conn_id(mgcp_rsp);
g_state := MSC_STATE_WAIT_MDCX_ACK;
var MgcpTransId trans_id := f_mgcp_alloc_tid();
BSSAP.send(ts_MDCX(trans_id, g_ep_name, "sendrecv", g_call_id, g_mgcp_conn_id));
}
/* receive MDCX ACK: wait + transmit CLEAR COMMAND */
[g_state == MSC_STATE_WAIT_MDCX_ACK] BSSAP.receive(tr_CRCX_ACK) -> value mgcp_rsp {
g_state := MSC_STATE_WAIT_CLEAR_COMPL
BSSAP.send(ts_BSSMAP_ClearCommand(9)); /* Cause: call control */
}
/* CLEAR COMPLETE from BSS (response to CLEAR COMMAND) */
[g_state == MSC_STATE_WAIT_CLEAR_COMPL] BSSAP.receive(tr_BSSMAP_ClearComplete) {
/* send DLCX */
g_state := MSC_STATE_WAIT_DLCX_ACK;
var MgcpTransId trans_id := f_mgcp_alloc_tid();
BSSAP.send(ts_DLCX(trans_id, g_ep_name, g_call_id));
}
[g_state == MSC_STATE_WAIT_DLCX_ACK] BSSAP.receive(tr_DLCX_ACK) {
BSSAP.send(RAN_Conn_Prim:MSC_CONN_PRIM_DISC_REQ);
setverdict(pass);
self.stop;
}
/* TODO: CLEAR REQUEST from BSS */
[] BSSAP.receive(RAN_Conn_Prim:MSC_CONN_PRIM_DISC_IND) {
setverdict(fail);
self.stop;
}
[] BSSAP.receive(PDU_BSSAP:?) -> value bssap {
log("Received unhandled SCCP-CO: ", bssap);
}
/* Guard timer has expired, close connection */
[] T.timeout {
BSSAP.send(RAN_Conn_Prim:MSC_CONN_PRIM_DISC_REQ);
setverdict(fail, "Timeout of guard timer");
self.stop;
}
}
}
}
}
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