395 lines
11 KiB
Plaintext
395 lines
11 KiB
Plaintext
/* GPRS-NS Emulation in TTCN-3
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* (C) 2018-2020 Harald Welte <laforge@gnumonks.org>
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* contributions by sysmocom - s.f.m.c. GmbH
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* All rights reserved.
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*
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* Released under the terms of GNU General Public License, Version 2 or
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* (at your option) any later version.
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*
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* SPDX-License-Identifier: GPL-2.0-or-later
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*/
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module NS_Emulation {
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import from NS_Types all;
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import from BSSGP_Types all;
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import from Osmocom_Types all;
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import from Osmocom_Gb_Types all;
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import from NS_Provider_IPL4 all;
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#ifdef NS_EMULATION_FR
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import from NS_Provider_FR all;
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#endif
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import from IPL4asp_Types all;
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type record NsUnitdataRequest {
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BssgpBvci bvci,
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Nsei nsei,
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octetstring sdu optional,
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PDU_BSSGP bssgp optional
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}
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template NsUnitdataRequest t_NsUdReq(template Nsei nsei, template BssgpBvci bvci, template octetstring sdu,
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template PDU_BSSGP bssgp) := {
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bvci := bvci,
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nsei := nsei,
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sdu := sdu,
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bssgp := bssgp
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}
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type record NsUnitdataIndication {
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BssgpBvci bvci,
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Nsei nsei,
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octetstring sdu optional,
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PDU_BSSGP bssgp optional
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}
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template NsUnitdataIndication t_NsUdInd(Nsei nsei, BssgpBvci bvci, octetstring sdu) := {
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bvci := bvci,
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nsei := nsei,
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sdu := sdu,
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bssgp := dec_PDU_BSSGP(sdu)
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}
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type record NsStatusIndication {
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Nsei nsei,
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Nsvci nsvci,
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NseState old_state,
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NseState new_state
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}
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template NsStatusIndication t_NsStsInd(Nsei nsei, Nsvci nsvci, NseState old_state, NseState state) := {
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nsei := nsei,
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nsvci := nsvci,
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old_state := old_state,
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new_state := state
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}
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type enumerated NseState {
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NSE_S_DEAD_BLOCKED,
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NSE_S_WAIT_RESET,
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NSE_S_ALIVE_BLOCKED,
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NSE_S_ALIVE_UNBLOCKED
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}
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/* port from our (internal) point of view */
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type port NS_SP_PT message {
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in NsUnitdataRequest;
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out NsUnitdataIndication,
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NsStatusIndication;
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} with { extension "internal" };
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/* port from the user point of view */
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type port NS_PT message {
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in ASP_Event,
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NsStatusIndication,
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NsUnitdataIndication;
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out NsUnitdataRequest;
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} with { extension "internal" };
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function NSStart(NSConfiguration init_config, charstring id := testcasename()) runs on NS_CT {
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config := init_config;
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f_init(id & "-NSemu");
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f_ScanEvents();
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}
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private function f_init(charstring id) runs on NS_CT {
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var Result res;
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if (ischosen(config.provider.ip)) {
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/* Connect the UDP socket */
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vc_NSP_IP := NS_Provider_IPL4_CT.create(id & "-provIP");
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connect(self:NSCP, vc_NSP_IP:NSE);
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vc_NSP_IP.start(NS_Provider_IPL4.main(config, id));
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#ifdef NS_EMULATION_FR
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} else if (ischosen(config.provider.fr)) {
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vc_NSP_FR := NS_Provider_FR_CT.create(id & "-provFR");
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connect(self:NSCP, vc_NSP_FR:NSE);
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vc_NSP_FR.start(NS_Provider_FR.main(config, id));
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#endif
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}
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f_change_state(NSE_S_DEAD_BLOCKED);
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}
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type component NS_Provider_CT {
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/* upper port, facing to NS_Emulation:NSCP */
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port NS_PROVIDER_PT NSE;
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/* lower layer ports (UDP/IP, Frame Relay) are added in derived components */
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};
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type enumerated NS_Provider_LinkStatus {
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NS_PROV_LINK_STATUS_UP,
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NS_PROV_LINK_STATUS_DOWN
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};
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type union NS_Provider_Evt {
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NS_Provider_LinkStatus link_status
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};
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/* port between NS_Provider and NS_CT */
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type port NS_PROVIDER_PT message {
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inout PDU_NS, NS_Provider_Evt;
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} with { extension "internal" };
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type component NS_CT {
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/* UDP port towards the bottom (IUT) */
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port NS_PROVIDER_PT NSCP;
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var NS_Provider_IPL4_CT vc_NSP_IP;
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#ifdef NS_EMULATION_FR
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var NS_Provider_FR_CT vc_NSP_FR;
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#endif
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/* NS-User SAP towards the user */
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port NS_SP_PT NS_SP;
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var NSConfiguration config;
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var NseState g_state := NSE_S_DEAD_BLOCKED;
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timer Tns_alive := 3.0;
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timer Tns_test := 10.0;
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timer Tns_block := 10.0;
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timer Tns_reset := 10.0;
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}
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type record NSConfigurationIP {
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AddressFamily address_family,
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PortNumber local_udp_port,
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charstring local_ip,
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PortNumber remote_udp_port,
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charstring remote_ip
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};
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type record NSConfigurationFR {
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charstring netdev, /* HDLC net-device for AF_PACKET socket */
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integer dlci
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};
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type union NSConfigurationP {
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NSConfigurationIP ip,
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NSConfigurationFR fr
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};
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type record NSConfiguration {
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NSConfigurationP provider,
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Nsvci nsvci,
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Nsvci nsei,
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boolean role_sgsn,
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boolean handle_sns
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}
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private function f_change_state(NseState new_state) runs on NS_CT {
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var NseState old_state := g_state;
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g_state := new_state;
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log("NS State Transition: ", old_state, " -> ", new_state);
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NS_SP.send(t_NsStsInd(config.nsei, config.nsvci, old_state, new_state));
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}
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private function f_sendReset() runs on NS_CT {
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NSCP.send(ts_NS_RESET(NS_CAUSE_OM_INTERVENTION, config.nsvci, config.nsei));
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Tns_reset.start;
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g_state := NSE_S_WAIT_RESET;
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}
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private function f_sendAlive() runs on NS_CT {
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NSCP.send(t_NS_ALIVE);
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Tns_alive.start;
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}
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private function f_sendUnblock() runs on NS_CT {
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NSCP.send(t_NS_UNBLOCK);
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Tns_block.start;
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}
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private function f_sendBlock(NsCause cause) runs on NS_CT {
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NSCP.send(ts_NS_BLOCK(cause, config.nsvci));
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Tns_block.start;
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}
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private altstep as_allstate() runs on NS_CT {
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var PDU_NS rf;
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var ASP_Event evt;
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/* transition to DEAD if t_alive times out */
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[] Tns_alive.timeout {
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log("Tns-alive expired: changing to DEAD_BLOCKED + starting Tns-test");
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f_change_state(NSE_S_DEAD_BLOCKED);
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Tns_test.start;
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}
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[] Tns_test.timeout {
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log("Tns-test expired: sending NS-ALIVE");
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f_sendAlive();
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}
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[config.role_sgsn] NSCP.receive(NS_Provider_Evt:{link_status:=NS_PROV_LINK_STATUS_UP}) {
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log("Provider Link came up: sending NS-ALIVE");
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f_sendAlive();
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Tns_test.start;
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}
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[not config.role_sgsn] NSCP.receive(NS_Provider_Evt:{link_status:=NS_PROV_LINK_STATUS_UP}) {
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log("Provider Link came up: sending NS-RESET");
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f_sendReset();
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}
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/* Stop t_alive when receiving ALIVE-ACK */
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[Tns_alive.running] NSCP.receive(t_NS_ALIVE_ACK) {
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log("NS-ALIVE-ACK received: stopping Tns-alive; starting Tns-test");
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Tns_alive.stop;
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Tns_test.start;
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}
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/* respond to NS-ALIVE with NS-ALIVE-ACK */
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[] NSCP.receive(t_NS_ALIVE) {
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NSCP.send(t_NS_ALIVE_ACK);
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}
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/* Respond to BLOCK for wrong NSVCI */
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[] NSCP.receive(tr_NS_BLOCK(?, ?)) -> value rf {
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log("Rx NS-BLOCK for unknown NSVCI");
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/* FIXME */
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}
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/* Respond to RESET with correct NSEI/NSVCI */
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[] NSCP.receive(tr_NS_RESET(?, config.nsvci, config.nsei)) -> value rf {
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f_change_state(NSE_S_ALIVE_BLOCKED);
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NSCP.send(ts_NS_RESET_ACK(config.nsvci, config.nsei));
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}
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/* Respond to RESET with wrong NSEI/NSVCI */
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[] NSCP.receive(tr_NS_RESET(?, ?, ?)) -> value rf {
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log("Rx NS-RESET for unknown NSEI/NSVCI");
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/* FIXME */
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}
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[config.role_sgsn and config.handle_sns and ischosen(config.provider.ip)] as_sns_sgsn();
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/* default case of handling unknown PDUs */
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[] NSCP.receive(PDU_NS: ?) -> value rf {
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log("Rx Unexpected NS PDU ", rf," in state ", g_state);
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NSCP.send(ts_NS_STATUS(NS_CAUSE_PDU_NOT_COMPATIBLE_WITH_PROTOCOL_STATE, rf));
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}
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}
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/* simple IP Sub-Network Service responder for the SGSN side. This is not a full implementation
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* of the protocol, merely sufficient to make the PCU/BSS side happy to proceed */
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private altstep as_sns_sgsn() runs on NS_CT {
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var PDU_NS rf;
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[] NSCP.receive(tr_SNS_SIZE(config.nsei)) -> value rf {
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/* blindly acknowledge whatever the PCU sends */
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NSCP.send(ts_SNS_SIZE_ACK(config.nsei, omit));
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}
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[] NSCP.receive(tr_SNS_SIZE(?)) {
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setverdict(fail, "SNS-SIZE from unexpected NSEI");
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self.stop;
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}
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[] NSCP.receive(tr_SNS_CONFIG(config.nsei, true,
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{tr_SNS_IPv4(config.provider.ip.remote_ip,
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config.provider.ip.remote_udp_port)})) -> value rf {
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/* blindly acknowledge whatever the PCU sends */
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NSCP.send(ts_SNS_CONFIG_ACK(config.nsei, omit));
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/* send a SNS-CONFIG in response and expect a SNS-CONFIG-ACK */
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var IP4_Elements v4 := { valueof(ts_SNS_IPv4(config.provider.ip.local_ip, config.provider.ip.local_udp_port)) };
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NSCP.send(ts_SNS_CONFIG(config.nsei, true, v4));
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alt {
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[] NSCP.receive(tr_SNS_CONFIG_ACK(config.nsei, omit)) {
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/* success */
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}
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[] NSCP.receive(tr_SNS_CONFIG_ACK(config.nsei, ?)) {
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setverdict(fail, "Unexpected SNS-CONFIG-NACK");
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self.stop;
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}
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}
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}
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[] NSCP.receive(tr_SNS_CONFIG(config.nsei, false, ?)) { /* ignore */}
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[] NSCP.receive(tr_SNS_CONFIG(config.nsei, true, ?)) {
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setverdict(fail, "Unexpected SNS-CONFIG content");
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self.stop;
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}
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[] NSCP.receive(tr_SNS_CONFIG(?, ?, ?)) {
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setverdict(fail, "SNS-CONFIG from unexpected NSEI");
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self.stop;
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}
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}
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private altstep as_alive_blocked() runs on NS_CT {
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var PDU_NS rf;
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/* bogus block, just respond with ACK */
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[] NSCP.receive(tr_NS_BLOCK(?, config.nsvci)) -> value rf {
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NSCP.send(ts_NS_BLOCK_ACK(config.nsvci));
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}
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/* Respond to UNBLOCK with UNBLOCK-ACK + change state */
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[] NSCP.receive(t_NS_UNBLOCK) -> value rf {
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NSCP.send(t_NS_UNBLOCK_ACK);
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Tns_block.stop;
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f_change_state(NSE_S_ALIVE_UNBLOCKED);
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}
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[] NSCP.receive(t_NS_UNBLOCK_ACK) -> value rf {
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Tns_block.stop;
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f_change_state(NSE_S_ALIVE_UNBLOCKED);
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}
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[] Tns_block.timeout {
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/* repeat unblock transmission */
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f_sendUnblock();
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}
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}
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private altstep as_alive_unblocked() runs on NS_CT {
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var NsUnitdataRequest ud_req;
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var PDU_NS rf;
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/* bogus unblock, just respond with ACK */
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[] NSCP.receive(t_NS_UNBLOCK) -> value rf {
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NSCP.send(t_NS_UNBLOCK_ACK);
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}
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/* Respond to BLOCK with BLOCK-ACK + change state */
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[] NSCP.receive(tr_NS_BLOCK(?, config.nsvci)) -> value rf {
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NSCP.send(ts_NS_BLOCK_ACK(config.nsvci));
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Tns_block.stop;
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f_change_state(NSE_S_ALIVE_BLOCKED);
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}
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[] NSCP.receive(tr_NS_BLOCK_ACK(config.nsvci)) -> value rf {
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Tns_block.stop;
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}
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/* NS-UNITDATA PDU from network to NS-UNITDATA.ind to user */
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[] NSCP.receive(tr_NS_UNITDATA(?, ?, ?)) -> value rf {
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NS_SP.send(t_NsUdInd(config.nsei,
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oct2int(rf.pDU_NS_Unitdata.bVCI),
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rf.pDU_NS_Unitdata.nS_SDU));
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}
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/* NS-UNITDATA.req from user to NS-UNITDATA PDU on network */
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[] NS_SP.receive(t_NsUdReq(config.nsei, ?, ?, omit)) -> value ud_req {
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/* using raw octetstring PDU */
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NSCP.send(ts_NS_UNITDATA(t_SduCtrlB, ud_req.bvci, ud_req.sdu));
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}
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[] NS_SP.receive(t_NsUdReq(config.nsei, ?, omit, ?)) -> value ud_req {
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/* using decoded BSSGP PDU that we need to encode first */
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var octetstring enc := enc_PDU_BSSGP(ud_req.bssgp);
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NSCP.send(ts_NS_UNITDATA(t_SduCtrlB, ud_req.bvci, enc));
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}
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}
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private altstep as_wait_reset() runs on NS_CT {
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var PDU_NS rf;
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[] Tns_reset.timeout {
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/* If the sending entity of an NS-RESET PDU receives no NS-RESET-ACK PDU before timer
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* Tns-reset expires the corresponding NS-VCs shall remain blocked and dead and the
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* entire reset procedure shall be repeated */
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f_sendReset();
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}
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[] NSCP.receive(tr_NS_RESET_ACK(config.nsvci, config.nsei)) -> value rf {
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Tns_reset.stop;
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f_change_state(NSE_S_ALIVE_BLOCKED);
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f_sendAlive();
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f_sendUnblock();
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}
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}
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private function f_ScanEvents() runs on NS_CT {
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var PDU_NS rf;
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while (true) {
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alt {
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[g_state == NSE_S_WAIT_RESET] as_wait_reset();
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[g_state == NSE_S_ALIVE_BLOCKED] as_alive_blocked();
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[g_state == NSE_S_ALIVE_UNBLOCKED] as_alive_unblocked();
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[] as_allstate();
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}
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}
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}
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}
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