/* GTPv2 Emulation in TTCN-3 * * (C) 2018-2020 Harald Welte * 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 */ module GTPv2_Emulation { import from IPL4asp_Types all; import from General_Types all; import from Osmocom_Types all; import from GTPv2_Types all; import from GTPv2_Templates all; import from GTPv2_CodecPort all; import from GTPv2_CodecPort_CtrlFunct all; import from UECUPS_Types all; import from UECUPS_CodecPort all; import from UECUPS_CodecPort_CtrlFunct all; /*********************************************************************** * Main Emulation Component ***********************************************************************/ modulepar { charstring mp_uecups_host := "127.0.0.1"; integer mp_uecups_port := UECUPS_SCTP_PORT; }; const integer GTP2C_PORT := 2123; const integer GTP1U_PORT := 2152; type record Gtp2EmulationCfg { HostName gtpc_bind_ip, IPL4asp_Types.PortNumber gtpc_bind_port, HostName gtpc_remote_ip, IPL4asp_Types.PortNumber gtpc_remote_port, //HostName gtpu_bind_ip, //PortNumber gtpu_bind_port, boolean sgw_role, boolean use_gtpu_daemon }; type component GTPv2_Emulation_CT { /* Communication with underlying GTP CodecPort */ port GTPv2C_PT GTP2C; /* Control port to GTP-U Daemon */ port UECUPS_CODEC_PT UECUPS; /* Communication with Clients */ port GTP2EM_PT TEID0; port GTP2EM_PT CLIENT; port GTP2EM_PROC_PT CLIENT_PROC; /* Configuration by the user */ var Gtp2EmulationCfg g_gtp2_cfg; /* State */ var GtpPeer g_peer; var integer g_gtp2c_id; var OCT1 g_restart_ctr; var uint16_t g_c_seq_nr; var TidTableRec TidTable[256]; var SeqTableRec SeqTable[256]; var ImsiTableRec ImsiTable[256]; var PidTableRec PidTable[256]; var integer g_uecups_conn_id; }; /* local TEID <-> ConnHdlr mapping */ type record TidTableRec { OCT4 teid, GTP2_ConnHdlr vc_conn }; /* local SeqNr <-> ConnHdlr mapping (until a response is received */ type record SeqTableRec { OCT3 seq, GTP2_ConnHdlr vc_conn }; /* IMSI <-> ConnHdlr mapping */ type record ImsiTableRec { hexstring imsi, GTP2_ConnHdlr vc_conn }; /* pid <-> ConnHdlr mapping (for UECUPS process termination indication) */ type record PidTableRec { /* process ID of the running process */ integer pid, /* component that started it */ GTP2_ConnHdlr vc_conn }; private function f_comp_by_teid(OCT4 teid) runs on GTPv2_Emulation_CT return GTP2_ConnHdlr { var integer i; for (i := 0; i < sizeof(TidTable); i := i+1) { if (isbound(TidTable[i].teid) and TidTable[i].teid == teid) { return TidTable[i].vc_conn; } } setverdict(fail, "No Component for TEID ", teid); mtc.stop; } private function f_seq_known(OCT3 seq) runs on GTPv2_Emulation_CT return boolean { var integer i; for (i := 0; i < sizeof(SeqTable); i := i+1) { if (isbound(SeqTable[i].seq) and SeqTable[i].seq == seq) { return true; } } return false; } private function f_comp_by_seq(OCT3 seq) runs on GTPv2_Emulation_CT return GTP2_ConnHdlr { var integer i; for (i := 0; i < sizeof(SeqTable); i := i+1) { if (isbound(SeqTable[i].seq) and SeqTable[i].seq == seq) { return SeqTable[i].vc_conn; } } setverdict(fail, "No Component for SEQ ", seq); mtc.stop; } private function f_comp_by_imsi(hexstring imsi) runs on GTPv2_Emulation_CT return GTP2_ConnHdlr { var integer i; for (i := 0; i < sizeof(ImsiTable); i := i+1) { if (isbound(ImsiTable[i].imsi) and ImsiTable[i].imsi == imsi) { return ImsiTable[i].vc_conn; } } setverdict(fail, "No Component for IMSI ", imsi); mtc.stop; } private function f_comp_by_pid(integer pid) runs on GTPv2_Emulation_CT return GTP2_ConnHdlr { var integer i; for (i := 0; i < sizeof(PidTable); i := i+1) { if (isbound(PidTable[i].pid) and PidTable[i].pid == pid) { /* fixme: remove */ return PidTable[i].vc_conn; } } setverdict(fail, "No Component for PID ", pid); mtc.stop; } private function f_tid_tbl_add(OCT4 teid, GTP2_ConnHdlr vc_conn) runs on GTPv2_Emulation_CT { var integer i; for (i := 0; i < sizeof(TidTable); i := i+1) { if (not isbound(TidTable[i].teid)) { TidTable[i].teid := teid; TidTable[i].vc_conn := vc_conn; return; } } testcase.stop("No Space in TidTable for ", teid); } private function f_seq_tbl_add(OCT3 seq, GTP2_ConnHdlr vc_conn) runs on GTPv2_Emulation_CT { var integer i; for (i := 0; i < sizeof(SeqTable); i := i+1) { if (not isbound(SeqTable[i].seq)) { SeqTable[i].seq := seq; SeqTable[i].vc_conn := vc_conn; return; } } testcase.stop("No Space in SeqTable for ", seq); } private function f_seq_tbl_del(OCT3 seq) runs on GTPv2_Emulation_CT { var integer i; for (i := 0; i < sizeof(SeqTable); i := i+1) { if (isbound(SeqTable[i].seq) and SeqTable[i].seq == seq) { SeqTable[i] := { seq := -, vc_conn := null } } } } private function f_imsi_tbl_add(hexstring imsi, GTP2_ConnHdlr vc_conn) runs on GTPv2_Emulation_CT { var integer i; for (i := 0; i < sizeof(ImsiTable); i := i+1) { if (not isbound(ImsiTable[i].imsi)) { ImsiTable[i].imsi := imsi; ImsiTable[i].vc_conn := vc_conn; return; } } testcase.stop("No Space in IMSI Table for ", imsi); } private function f_pid_tbl_add(integer pid, GTP2_ConnHdlr vc_conn) runs on GTPv2_Emulation_CT { var integer i; for (i := 0; i < sizeof(PidTable); i := i+1) { if (not isbound(PidTable[i].pid)) { PidTable[i].pid := pid; PidTable[i].vc_conn := vc_conn; return; } } testcase.stop("No Space in PID Table for ", pid); } /* allocate an unused local teid */ private function f_alloc_teid() runs on GTPv2_Emulation_CT return OCT4 { var OCT4 teid; var integer i, j; for (i := 0; i < 100; i := i+1) { teid := f_rnd_octstring(4); for (j := 0; j < sizeof(TidTable); j := j+1) { if (isbound(TidTable) and TidTable[i].teid == teid) { continue; } } /* we iterated over all entries and found no match: great! */ return teid; } testcase.stop("Cannot find unused TEID after ", i, " attempts"); } /* obtain the IMSI from a GTPv2C PDU, if there is any IMSI contained. The way how the TITAN * GTPv2 decoders are structured (explict IE members rather than a list/set of generic IE structures) * doesn't make this easy, but requires lots of boilerplate code. Oh well.. */ function f_gtp2c_extract_imsi(PDU_GTPCv2 gtp) return template (omit) hexstring { if (ischosen(gtp.gtpcv2_pdu.createSessionRequest)) { if (ispresent(gtp.gtpcv2_pdu.createSessionRequest.iMSI)) { return gtp.gtpcv2_pdu.createSessionRequest.iMSI.iMSI_Value; } } else if (ischosen(gtp.gtpcv2_pdu.downlinkDataNotification)) { if (ispresent(gtp.gtpcv2_pdu.downlinkDataNotification.iMSI)) { return gtp.gtpcv2_pdu.downlinkDataNotification.iMSI.iMSI_Value; } } else if (ischosen(gtp.gtpcv2_pdu.downlinkDataNotificationAcknowledgement)) { if (ispresent(gtp.gtpcv2_pdu.downlinkDataNotificationAcknowledgement.iMSI)) { return gtp.gtpcv2_pdu.downlinkDataNotificationAcknowledgement.iMSI.iMSI_Value; } } else if (ischosen(gtp.gtpcv2_pdu.downlinkDataNotificationFailureIndication)) { if (ispresent(gtp.gtpcv2_pdu.downlinkDataNotificationFailureIndication.iMSI)) { return gtp.gtpcv2_pdu.downlinkDataNotificationFailureIndication.iMSI.iMSI_Value; } } else if (ischosen(gtp.gtpcv2_pdu.createIndirectDataForwardingTunnelRequest)) { if (ispresent(gtp.gtpcv2_pdu.createIndirectDataForwardingTunnelRequest.iMSI)) { return gtp.gtpcv2_pdu.createIndirectDataForwardingTunnelRequest.iMSI.iMSI_Value; } } else if (ischosen(gtp.gtpcv2_pdu.stopPagingIndication)) { if (ispresent(gtp.gtpcv2_pdu.stopPagingIndication.iMSI)) { return gtp.gtpcv2_pdu.stopPagingIndication.iMSI.iMSI_Value; } } else if (ischosen(gtp.gtpcv2_pdu.forwardRelocationRequest)) { if (ispresent(gtp.gtpcv2_pdu.forwardRelocationRequest.iMSI)) { return gtp.gtpcv2_pdu.forwardRelocationRequest.iMSI.iMSI_Value; } } else if (ischosen(gtp.gtpcv2_pdu.contextRequest)) { if (ispresent(gtp.gtpcv2_pdu.contextRequest.iMSI)) { return gtp.gtpcv2_pdu.contextRequest.iMSI.iMSI_Value; } } else if (ischosen(gtp.gtpcv2_pdu.identificationResponse)) { if (ispresent(gtp.gtpcv2_pdu.identificationResponse.iMSI)) { return gtp.gtpcv2_pdu.identificationResponse.iMSI.iMSI_Value; } } else if (ischosen(gtp.gtpcv2_pdu.changeNotificationRequest)) { if (ispresent(gtp.gtpcv2_pdu.changeNotificationRequest)) { return gtp.gtpcv2_pdu.changeNotificationRequest.iMSI.iMSI_Value; } } else if (ischosen(gtp.gtpcv2_pdu.changeNotificationResponse)) { if (ispresent(gtp.gtpcv2_pdu.changeNotificationResponse.iMSI)) { return gtp.gtpcv2_pdu.changeNotificationResponse.iMSI.iMSI_Value; } } else if (ischosen(gtp.gtpcv2_pdu.relocationCancelRequest)) { if (ispresent(gtp.gtpcv2_pdu.relocationCancelRequest.iMSI)) { return gtp.gtpcv2_pdu.relocationCancelRequest.iMSI.iMSI_Value; } } else if (ischosen(gtp.gtpcv2_pdu.uE_RegistrationQueryRequest)) { if (ispresent(gtp.gtpcv2_pdu.uE_RegistrationQueryRequest.iMSI)) { return gtp.gtpcv2_pdu.uE_RegistrationQueryRequest.iMSI.iMSI_Value; } } else if (ischosen(gtp.gtpcv2_pdu.uE_RegistrationQueryResponse)) { if (ispresent(gtp.gtpcv2_pdu.uE_RegistrationQueryResponse.iMSI)) { return gtp.gtpcv2_pdu.uE_RegistrationQueryResponse.iMSI.iMSI_Value; } } else if (ischosen(gtp.gtpcv2_pdu.suspendNotification)) { if (ispresent(gtp.gtpcv2_pdu.suspendNotification.iMSI)) { return gtp.gtpcv2_pdu.suspendNotification.iMSI.iMSI_Value; } } else if (ischosen(gtp.gtpcv2_pdu.resumeNotification)) { if (ispresent(gtp.gtpcv2_pdu.resumeNotification.iMSI)) { return gtp.gtpcv2_pdu.resumeNotification.iMSI.iMSI_Value; } } else if (ischosen(gtp.gtpcv2_pdu.cSPagingIndication)) { if (ispresent(gtp.gtpcv2_pdu.cSPagingIndication.iMSI)) { return gtp.gtpcv2_pdu.cSPagingIndication.iMSI.iMSI_Value; } } else if (ischosen(gtp.gtpcv2_pdu.pGW_DownlinkTriggeringNotification)) { if (ispresent(gtp.gtpcv2_pdu.pGW_DownlinkTriggeringNotification.iMSI)) { return gtp.gtpcv2_pdu.pGW_DownlinkTriggeringNotification.iMSI.iMSI_Value; } } else if (ischosen(gtp.gtpcv2_pdu.pGW_DownlinkTriggeringAcknowledge)) { if (ispresent(gtp.gtpcv2_pdu.pGW_DownlinkTriggeringAcknowledge.iMSI)) { return gtp.gtpcv2_pdu.pGW_DownlinkTriggeringAcknowledge.iMSI.iMSI_Value; } } else if (ischosen(gtp.gtpcv2_pdu.traceSessionActivation)) { if (ispresent(gtp.gtpcv2_pdu.traceSessionActivation.iMSI)) { return gtp.gtpcv2_pdu.traceSessionActivation.iMSI.iMSI_Value; } } return omit; } private template (value) SctpTuple ts_SCTP(template (omit) integer ppid := omit) := { sinfo_stream := omit, sinfo_ppid := ppid, remSocks := omit, assocId := omit }; function tr_UECUPS_RecvFrom_R(template PDU_UECUPS msg) runs on GTPv2_Emulation_CT return template UECUPS_RecvFrom { var template UECUPS_RecvFrom mrf := { connId := g_uecups_conn_id, remName := ?, remPort := ?, locName := ?, locPort := ?, msg := msg } return mrf; } private template PortEvent tr_SctpAssocChange := { sctpEvent := { sctpAssocChange := ? } } private template PortEvent tr_SctpPeerAddrChange := { sctpEvent := { sctpPeerAddrChange := ? } } private function f_uecups_xceive(template (value) PDU_UECUPS tx, template PDU_UECUPS rx_t := ?) runs on GTPv2_Emulation_CT return PDU_UECUPS { timer T := 10.0; var UECUPS_RecvFrom mrf; UECUPS.send(t_UECUPS_Send(g_uecups_conn_id, tx)); alt { [] UECUPS.receive(tr_UECUPS_RecvFrom_R(rx_t)) -> value mrf { } [] UECUPS.receive(tr_SctpAssocChange) { repeat; } [] UECUPS.receive(tr_SctpPeerAddrChange) { repeat; } [] T.timeout { setverdict(fail, "Timeout waiting for ", rx_t); mtc.stop; } } return mrf.msg; } private function f_init(Gtp2EmulationCfg cfg) runs on GTPv2_Emulation_CT { var Result res; map(self:GTP2C, system:GTP2C); res := GTPv2_CodecPort_CtrlFunct.f_IPL4_listen(GTP2C, cfg.gtpc_bind_ip, cfg.gtpc_bind_port, {udp:={}}); g_gtp2c_id := res.connId; g_restart_ctr := f_rnd_octstring(1); g_c_seq_nr := f_rnd_int(65535); g_gtp2_cfg := cfg; g_peer := { connId := g_gtp2c_id, remName := g_gtp2_cfg.gtpc_remote_ip, remPort := g_gtp2_cfg.gtpc_remote_port } if (g_gtp2_cfg.use_gtpu_daemon) { map(self:UECUPS, system:UECUPS); res := UECUPS_CodecPort_CtrlFunct.f_IPL4_connect(UECUPS, mp_uecups_host, mp_uecups_port, "", -1, -1, { sctp := valueof(ts_SCTP) }); if (not ispresent(res.connId)) { setverdict(fail, "Could not connect UECUPS socket, check your configuration"); testcase.stop; } g_uecups_conn_id := res.connId; /* clear all tunnel state in the daemon at start */ f_uecups_xceive({reset_all_state := {}}, {reset_all_state_res:=?}); } /* make sure we always pass incoming UECUPS indications whenever receiving fom the UECUPS port */ activate(as_uecups_ind()); } private altstep as_uecups_ind() runs on GTPv2_Emulation_CT { var UECUPS_RecvFrom rx; var GTP2_ConnHdlr vc_conn; /* handle incoming program_term_ind; dispatch to whatever component started the process */ [] UECUPS.receive(tr_UECUPS_RecvFrom_R({program_term_ind:=?})) -> value rx { vc_conn := f_comp_by_pid(rx.msg.program_term_ind.pid); CLIENT.send(rx.msg.program_term_ind) to vc_conn; /* FIXME: remove from table */ repeat; } } function main(Gtp2EmulationCfg cfg) runs on GTPv2_Emulation_CT { var Gtp2cUnitdata g2c_ud; var PDU_GTPCv2 g2c; var GTP2_ConnHdlr vc_conn; var hexstring imsi; var OCT4 teid; var PDU_UECUPS rx_uecups; var UECUPS_CreateTun gtc; var UECUPS_DestroyTun gtd; var UECUPS_StartProgram sprog; f_init(cfg); while (true) { alt { /* route inbound GTP2-C based on TEID, SEQ or IMSI */ [] GTP2C.receive(Gtp2cUnitdata:?) -> value g2c_ud { var template hexstring imsi_t := f_gtp2c_extract_imsi(g2c_ud.gtpc); if (not ispresent(g2c_ud.gtpc.tEID) or g2c_ud.gtpc.tEID == int2oct(0, 4)) { /* if this is a response, route by SEQ */ if (match(g2c_ud.gtpc, tr_PDU_GTP2C_msgtypes(gtp2_responses)) and f_seq_known(g2c_ud.gtpc.sequenceNumber)) { vc_conn := f_comp_by_seq(g2c_ud.gtpc.sequenceNumber); CLIENT.send(g2c_ud.gtpc) to vc_conn; } else { TEID0.send(g2c_ud.gtpc); } } else if (ispresent(g2c_ud.gtpc.tEID) and g2c_ud.gtpc.tEID != int2oct(0, 4)) { vc_conn := f_comp_by_teid(g2c_ud.gtpc.tEID); CLIENT.send(g2c_ud.gtpc) to vc_conn; } else if (isvalue(imsi_t)) { vc_conn := f_comp_by_imsi(valueof(imsi_t)); CLIENT.send(g2c_ud.gtpc) to vc_conn; } else { /* Send to all clients */ var integer i; for (i := 0; i < sizeof(TidTable); i := i+1) { if (isbound(TidTable[i].teid) and TidTable[i].teid == teid) { CLIENT.send(g2c_ud.gtpc) to TidTable[i].vc_conn; } } } /* remove sequence number if response was received */ if (match(g2c_ud.gtpc, tr_PDU_GTP2C_msgtypes(gtp2_responses))) { f_seq_tbl_del(g2c_ud.gtpc.sequenceNumber); } } [] TEID0.receive(PDU_GTPCv2:?) -> value g2c sender vc_conn { /* patch in the next sequence number */ /* FIXME: do this only for outbound requests */ g2c.sequenceNumber := int2oct(g_c_seq_nr, 3); g_c_seq_nr := g_c_seq_nr + 1; /* build Gtp2cUnitdata */ g2c_ud := { peer := g_peer, gtpc := g2c }; GTP2C.send(g2c_ud); if (match(g2c, tr_PDU_GTP2C_msgtypes(gtp2_requests))) { f_seq_tbl_add(g2c.sequenceNumber, vc_conn); } } [] CLIENT.receive(PDU_GTPCv2:?) -> value g2c sender vc_conn { /* patch in the next sequence number */ /* FIXME: do this only for outbound requests */ g2c.sequenceNumber := int2oct(g_c_seq_nr, 3); g_c_seq_nr := g_c_seq_nr + 1; /* build Gtp2cUnitdata */ g2c_ud := { peer := g_peer, gtpc := g2c }; GTP2C.send(g2c_ud); if (match(g2c, tr_PDU_GTP2C_msgtypes(gtp2_requests))) { f_seq_tbl_add(g2c.sequenceNumber, vc_conn); } } [] CLIENT_PROC.getcall(GTP2EM_register_imsi:{?}) -> param(imsi) sender vc_conn { f_imsi_tbl_add(imsi, vc_conn); CLIENT_PROC.reply(GTP2EM_register_imsi:{imsi}) to vc_conn; } [] CLIENT_PROC.getcall(GTP2EM_register_teid:{?}) -> param(teid) sender vc_conn { f_tid_tbl_add(teid, vc_conn); CLIENT_PROC.reply(GTP2EM_register_teid:{teid}) to vc_conn; } [] CLIENT_PROC.getcall(GTP2EM_allocate_teid:{}) -> sender vc_conn { var OCT4 t := f_alloc_teid(); f_tid_tbl_add(t, vc_conn); CLIENT_PROC.reply(GTP2EM_allocate_teid:{} value t) to vc_conn; } [] CLIENT_PROC.getcall(GTP2EM_create_tunnel:{?}) -> param(gtc) sender vc_conn { rx_uecups := f_uecups_xceive({create_tun := gtc}, {create_tun_res:={result:=OK}}); CLIENT_PROC.reply(GTP2EM_create_tunnel:{gtc}) to vc_conn; } [] CLIENT_PROC.getcall(GTP2EM_destroy_tunnel:{?}) -> param(gtd) sender vc_conn { rx_uecups := f_uecups_xceive({destroy_tun := gtd}, {destroy_tun_res:={result:=OK}}); CLIENT_PROC.reply(GTP2EM_destroy_tunnel:{gtd}) to vc_conn; } [] CLIENT_PROC.getcall(GTP2EM_start_program:{?}) -> param(sprog) sender vc_conn { rx_uecups := f_uecups_xceive({start_program := sprog}, {start_program_res:=?}); /* if successful: store (pid, vc_conn) tuple so we can route program_term_ind */ if (rx_uecups.start_program_res.result == OK) { f_pid_tbl_add(rx_uecups.start_program_res.pid, vc_conn); } CLIENT_PROC.reply(GTP2EM_start_program:{sprog} value rx_uecups.start_program_res) to vc_conn; } } } } /*********************************************************************** * Interaction between Main and Client Components ***********************************************************************/ type port GTP2EM_PT message { inout PDU_GTPCv2, UECUPS_ProgramTermInd; } with { extension "internal" }; signature GTP2EM_register_imsi(hexstring imsi); signature GTP2EM_register_teid(OCT4 teid); signature GTP2EM_allocate_teid() return OCT4; signature GTP2EM_create_tunnel(UECUPS_CreateTun gtc); signature GTP2EM_destroy_tunnel(UECUPS_DestroyTun gtd); signature GTP2EM_start_program(UECUPS_StartProgram sprog) return UECUPS_StartProgramRes; type port GTP2EM_PROC_PT procedure { inout GTP2EM_register_imsi, GTP2EM_register_teid, GTP2EM_allocate_teid, GTP2EM_create_tunnel, GTP2EM_destroy_tunnel, GTP2EM_start_program; } with { extension "internal" }; /*********************************************************************** * Client Component ***********************************************************************/ type component GTP2_ConnHdlr { port GTP2EM_PT GTP2; port GTP2EM_PROC_PT GTP2_PROC; }; function f_gtp2_register_imsi(hexstring imsi) runs on GTP2_ConnHdlr { GTP2_PROC.call(GTP2EM_register_imsi:{imsi}) { [] GTP2_PROC.getreply(GTP2EM_register_imsi:{imsi}); } } function f_gtp2_register_teid(OCT4 teid) runs on GTP2_ConnHdlr { GTP2_PROC.call(GTP2EM_register_teid:{teid}) { [] GTP2_PROC.getreply(GTP2EM_register_teid:{teid}); } } function f_gtp2_allocate_teid() runs on GTP2_ConnHdlr return OCT4 { var OCT4 t; GTP2_PROC.call(GTP2EM_allocate_teid:{}) { [] GTP2_PROC.getreply(GTP2EM_allocate_teid:{}) -> value t { return t; } } } function f_gtp2_create_tunnel(template (value) UECUPS_CreateTun gtc) runs on GTP2_ConnHdlr { GTP2_PROC.call(GTP2EM_create_tunnel:{valueof(gtc)}) { [] GTP2_PROC.getreply(GTP2EM_create_tunnel:{gtc}); } } function f_gtp2_destroy_tunnel(template (value) UECUPS_DestroyTun gtd) runs on GTP2_ConnHdlr { GTP2_PROC.call(GTP2EM_destroy_tunnel:{valueof(gtd)}) { [] GTP2_PROC.getreply(GTP2EM_destroy_tunnel:{gtd}); } } function f_gtp2_start_program(template (value) UECUPS_StartProgram sprog) runs on GTP2_ConnHdlr return UECUPS_StartProgramRes { var UECUPS_StartProgramRes res; GTP2_PROC.call(GTP2EM_start_program:{valueof(sprog)}) { [] GTP2_PROC.getreply(GTP2EM_start_program:{sprog}) -> value res; } return res; } }