library/GTP_Templates.ttcn

/* GTP Templates in TTCN-3
 * (C) 2018 Harald Welte <laforge@gnumonks.org>
 * contributions by sysmocom - s.f.m.c. GmbH
 * 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 GTP_Templates {

	import from General_Types all;
	import from Osmocom_Types all;
	import from GTPC_Types all;
	import from GTPU_Types all;
	import from GTP_CodecPort all;
	import from IPCP_Types all;
	import from GSM_Types all; // RoutingAreaIdentification, CellIdentity

	type record GTP_CellId {
		RoutingAreaIdentification	ra_id,
		CellIdentity			cell_id
	} with { encode "RAW" };

	template (value) GTP_CellId ts_GTP_CellId(template (value) RoutingAreaIdentification rai, CellIdentity cell_id) := {
		ra_id := rai,
		cell_id := cell_id
	};

	/* Table 38 of 3GPP TS 29.060 */
	type enumerated GTP_Cause {
		GTP_CAUSE_REQUEST_IMEI			(1),
		GTP_CAUSE_REQUEST_IMSI_AND_IMEI		(2),
		GTP_CAUSE_NO_IDENTITY_NEDED		(3),
		GTP_CAUSE_MS_REFUSES			(4),
		GTP_CAUSE_MS_IS_NOT_GPRS_RESPONDING	(5),
		/* reserved */
		GTP_CAUSE_REQUEST_ACCEPTED		(128)
		/* FIXME */
	};

	private function f_oct_or_wc(template integer inp, integer len) return template octetstring {
		if (istemplatekind(inp, "omit")) {
			return omit;
		} else if (istemplatekind(inp, "*")) {
			return *;
		} else if (istemplatekind(inp, "?")) {
			return ?;
		}
		return int2oct(valueof(inp), len);
	}

	private function f_hex_or_wc(template integer inp, integer len) return template hexstring {
		if (istemplatekind(inp, "omit")) {
			return omit;
		} else if (istemplatekind(inp, "*")) {
			return *;
		} else if (istemplatekind(inp, "?")) {
			return ?;
		}
		return int2hex(valueof(inp), len);
	}

	/* generalized GTP-C receive template */
	template PDU_GTPC tr_GTP1C_PDU(template OCT1 msg_type, template OCT4 teid, template GTPC_PDUs pdu := ?) := {
		/* N-PDU Number flag (PN) shall be set to '0'. A GTP-C receiver shall not return an
		 * error if this flag is set to '1'. */
		pn_bit := '0'B,
		/* Sequence number flag (S) shall be set to '1'. */
		s_bit := '1'B,
		e_bit := ?,
		spare := ?,
		/* Protocol Type flag (PT) shall be set to '1'.*/
		pt := '1'B,
		/* Version shall be set to decimal 1 ('001'). */
		version := '001'B,
		messageType := msg_type,
		lengthf := ?,
		teid := teid,
		opt_part := *,
		gtpc_pdu := pdu
	}

	/* generalized GTP-C send template */
	template PDU_GTPC ts_GTP1C_PDU(OCT1 msg_type, OCT4 teid, GTPC_PDUs pdu, uint16_t seq_nr) := {
		/* N-PDU Number flag (PN) shall be set to '0'. A GTP-C receiver shall not return an
		 * error if this flag is set to '1'. */
		pn_bit := '0'B,
		/* Sequence number flag (S) shall be set to '1'. */
		s_bit := '1'B,
		e_bit := '0'B,
		spare := '0'B,
		/* Protocol Type flag (PT) shall be set to '1'.*/
		pt := '1'B,
		/* Version shall be set to decimal 1 ('001'). */
		version := '001'B,
		messageType := msg_type,
		lengthf := 0,	/* we assume encoder overwrites this */
		teid := teid,
		opt_part := {
			sequenceNumber := int2oct(seq_nr, 2),
			npduNumber := '00'O,
			nextExtHeader := '00'O,
			gTPC_extensionHeader_List := omit
		},
		gtpc_pdu := pdu
	}

	/* recovery IE */
	template Recovery_gtpc ts_Recovery(OCT1 restart_counter) := {
		type_gtpc := '0E'O,
		restartCounter := restart_counter
	}

	template Recovery_gtpc tr_Recovery(template OCT1 restart_counter) := {
		type_gtpc := '0E'O,
		restartCounter := restart_counter
	}

	/* template matching reception of GTP-C echo-request */
	template Gtp1cUnitdata tr_GTPC_MsgType(template GtpPeer peer, template OCT1 msg_type, template OCT4 teid, template GTPC_PDUs pdus := ?) := {
		peer := peer,
		gtpc := tr_GTP1C_PDU(msg_type, teid, pdus)
	}

	/* template matching reception of GTP-C echo-request */
	template Gtp1cUnitdata tr_GTPC_PING(template GtpPeer peer) := tr_GTPC_MsgType(peer, echoRequest, '00000000'O);

	template GTPC_PDUs tr_EchoRespPDU(template OCT1 restart_counter) := {
		echoResponse := {
			recovery := tr_Recovery(restart_counter),
			private_extension_gtpc := *
		}
	}

	/* template matching reception of GTP-C echo-response */
	template Gtp1cUnitdata tr_GTPC_PONG(template GtpPeer peer) := tr_GTPC_MsgType(peer, echoResponse, '00000000'O, tr_EchoRespPDU(?));

	template GTPC_PDUs ts_EchoRespPDU(OCT1 restart_counter) := {
		echoResponse := {
			recovery := ts_Recovery(restart_counter),
			private_extension_gtpc := omit
		}
	}

	/* master template for senidng a GTP-C echo response */
	template Gtp1cUnitdata ts_GTPC_PONG(GtpPeer peer, uint16_t seq, OCT1 rest_ctr) := {
		peer := peer,
		gtpc := ts_GTP1C_PDU(echoResponse, '00000000'O, valueof(ts_EchoRespPDU(rest_ctr)), seq)
	}

	template GTPC_PDUs ts_EchoReqPDU := {
		echoRequest := {
			private_extension_gtpc := omit
		}
	}

	/* master template for sending a GTP-C echo request */
	template Gtp1cUnitdata ts_GTPC_PING(GtpPeer peer, uint16_t seq) := {
		peer := peer,
		gtpc := ts_GTP1C_PDU(echoRequest, '00000000'O, valueof(ts_EchoReqPDU), seq)
	}

	template EndUserAddress t_EuaIPv4(template OCT4 ip_addr) := {
		type_gtpc := '80'O,
		endUserAddress := {
			endUserAddressIPv4 := {
				lengthf := 2,
				pdp_typeorg := '0001'B,
				spare := '1111'B,
				pdp_typenum := '21'O,
				ipv4_address := ip_addr
			}
		}
	}
	template EndUserAddress t_EuaIPv4Dyn := t_EuaIPv4(omit);
	template EndUserAddress tr_EuaIPv4(template OCT4 ip_addr) modifies t_EuaIPv4 := {
		endUserAddress := {
			endUserAddressIPv4 := {
				lengthf := 2+lengthof(ip_addr)
			}
		}
	}

	template EndUserAddress t_EuaIPv6(template OCT16 ip_addr) := {
		type_gtpc := '80'O,
		endUserAddress := {
			endUserAddressIPv6 := {
				lengthf := 2,
				pdp_typeorg := '0001'B,
				spare := '1111'B,
				pdp_typenum := '57'O,
				ipv6_address := ip_addr
			}
		}
	}
	template EndUserAddress t_EuaIPv6Dyn := t_EuaIPv6(omit);
	template EndUserAddress tr_EuaIPv6(template OCT16 ip_addr) modifies t_EuaIPv6 := {
		endUserAddress := {
			endUserAddressIPv6 := {
				lengthf := 2+lengthof(ip_addr)
			}
		}
	}

	/* 3GPP TS 29.060 Figure 37A: End User Address Information Element for IPv4v6 (both static) */
	template EndUserAddress t_EuaIPv4v6(template OCT4 ip_addr4, template OCT16 ip_addr6) := {
		type_gtpc := '80'O,
		endUserAddress := {
			endUserAddressIPv4andIPv6 := {
				lengthf := 2,
				pdp_typeorg := '0001'B,
				spare := '1111'B,
				pdp_typenum := '8D'O,
				ipv4_address := ip_addr4,
				ipv6_address := ip_addr6
			}
		}
	}
	template EndUserAddress t_EuaIPv4Dynv6Dyn := t_EuaIPv4v6(omit, omit);
	template EndUserAddress tr_EuaIPv4v6(template OCT4 ip_addr4, template OCT16 ip_addr6) modifies t_EuaIPv4v6 := {
		endUserAddress := {
			endUserAddressIPv4andIPv6 := {
				lengthf := 2+lengthof(ip_addr4)+lengthof(ip_addr6)
			}
		}
	}

	template AccessPointName ts_APN(octetstring apn) := {
		type_gtpc := '83'O,
		lengthf := lengthof(apn),
		apn_value := apn
	}

	template GSN_Address_GTPC ts_GsnAddr(octetstring ip_addr) := {
		type_gtpc := '85'O,
		lengthf := lengthof(ip_addr),
		addressf := ip_addr
	}

	template MSISDN ts_Msisdn(octetstring msisdn) := {
		type_gtpc := '86'O,
		lengthf := lengthof(msisdn),
		msisdn := msisdn
	}

	template QualityOfServiceProfile ts_QosDefault := {
		type_gtpc := '87'O,
		lengthf := 4,
		allocRetensionPrio := '00'O,
		qos_ProfileValue := {
			reliabilityClass := '011'B,
			delayClass := '001'B,
			spare1 := '00'B,
			precedenceClass := '010'B,
			spare2 := '0'B,
			peakThroughput := '1001'B,
			meanThroughput := '11111'B,
			spare3 := '000'B,
			deliverErroneusSDU := omit,
			deliveryOrder := omit,
			trafficClass := omit,
			maxSDUSize := omit,
			maxBitrateUplink := omit,
			maxBitrateDownlink := omit,
			sduErrorRatio := omit,
			residualBER := omit,
			trafficHandlingPriority := omit,
			transferDelay := omit,
			guaranteedBitRateUplink := omit,
			guaranteedBitRateDownlink := omit,
			sourceStatisticsDescriptor := omit,
			signallingIndication := omit,
			spare4 := omit,
			maxBitrateDownlinkExt := omit,
			guaranteedBitRateDownlinkExt := omit,
			maxBitrateUplinkExt := omit,
			guaranteedBitRateUplinkExt := omit
		}
	}

	template IMSI_gtpc ts_Imsi(hexstring digits) := {
		type_gtpc := '02'O,
		digits := digits,
		padding := 'F'H
	}

	function f_ts_RATType(template (omit) OCT1 ratType := omit) return template (omit) RATType {
		var template (omit) RATType rt;
		if (istemplatekind(ratType, "omit")) {
			rt := omit;
		} else {
			rt := {
				type_gtpc := '97'O,
				lengthf := 1,
				ratTypeValue := ratType
			};
		}
		return rt;
	}

	template GTPC_PDUs ts_CreatePdpPDU(hexstring imsi, OCT1 restart_ctr, OCT4 teid_data, OCT4 teid_ctrl,
					   BIT4 nsapi, EndUserAddress eua, octetstring apn,
					   octetstring sgsn_ip_sign, octetstring sgsn_ip_data,
					   octetstring msisdn, template ProtConfigOptions pco := omit,
					   template (omit) OCT1 ratType := omit) := {
		createPDPContextRequest := {
			imsi := ts_Imsi(imsi),
			rai := omit,
			recovery := ts_Recovery(restart_ctr),
			selectionMode := {
				type_gtpc := '0F'O,
				selectModeValue := '00'B,
				spare := '111111'B
			},
			teidDataI := {
				type_gtpc := '00'O,
				teidDataI := teid_data
			},
			teidControlPlane := {
				type_gtpc := '00'O,
				teidControlPlane := teid_ctrl
			},
			nsapi := {
				type_gtpc := '00'O,
				nsapi := nsapi,
				unused := '0000'B
			},
			linked_nsapi := omit,
			charging_char := omit,
			trace_ref := omit,
			trace_type := omit,
			endUserAddress := eua,
			accessPointName := ts_APN(apn),
			protConfigOptions := pco,
			sgsn_addr_signalling := ts_GsnAddr(sgsn_ip_sign),
			sgsn_addr_traffic := ts_GsnAddr(sgsn_ip_data),
			msisdn := ts_Msisdn(msisdn),
			qualityOfServiceProfile := ts_QosDefault,
			tft := omit,
			triggerId := omit,
			omcId := omit,
			commonFlags := omit,
			aPN_Restriction := omit,
			ratType := f_ts_RATType(ratType),
			userLocationInformation := omit,
			mS_TimeZone := omit,
			imeisv := omit,
			camelChargingInformationContainer := omit,
			additionalTraceInfo := omit,
			correlationID := omit,
			evolvedAllocationRetentionPriorityI := omit,
			extendedCommonFlags := omit,
			userCSGInformation := omit,
			aPN_AMBR := omit,
			signallingPriorityIndication := omit,
			cN_OperatorSelectionEntity := omit,
			private_extension_gtpc := omit
		}
	}

	template Gtp1cUnitdata ts_GTPC_CreatePDP(GtpPeer peer, uint16_t seq, hexstring imsi,
						 OCT1 restart_ctr, OCT4 teid_data,
						 OCT4 teid_ctrl, BIT4 nsapi, EndUserAddress eua,
						 octetstring apn, octetstring sgsn_ip_sign,
						 octetstring sgsn_ip_data, octetstring msisdn,
						 template ProtConfigOptions pco := omit,
						 template (omit) OCT1 ratType := omit) := {
		peer := peer,
		gtpc := ts_GTP1C_PDU(createPDPContextRequest, '00000000'O,
					valueof(ts_CreatePdpPDU(imsi, restart_ctr, teid_data, teid_ctrl,
								nsapi, eua, apn, sgsn_ip_sign,
								sgsn_ip_data, msisdn, pco, ratType)), seq)
	}


	template NSAPI_GTPC ts_NSAPI(BIT4 nsapi) := {
		type_gtpc := '14'O,
		nsapi := nsapi,
		unused := '0000'B
	}

	template ReorderingRequired ts_ReorderReq(boolean req := false) := {
		type_gtpc := '08'O,
		reordreq := bool2bit(req),
		spare := '0000000'B
	}

	template GTPC_PDUs ts_CreatePdpRespPDU(OCT1 cause, OCT4 teid_data, OCT4 teid_ctrl, BIT4 nsapi,
						octetstring ggsn_ip_sign, octetstring ggsn_ip_data,
						OCT4 chg_id, template EndUserAddress eua := omit,
						template Recovery_gtpc recovery := omit,
						template ProtConfigOptions pco := omit) := {
		createPDPContextResponse := {
			cause := { '00'O, cause },
			reorderingRequired := ts_ReorderReq(false),
			recovery := recovery,
			teidDataI := {
				type_gtpc := '00'O,
				teidDataI := teid_data
			},
			teidControlPlane := {
				type_gtpc := '00'O,
				teidControlPlane := teid_ctrl
			},
			nsapi := ts_NSAPI(nsapi),
			chargingID := {
				type_gtpc := '7F'O,
				chargingID := chg_id
			},
			endUserAddress := eua,
			protConfigOptions := pco,
			ggsn_addr_controlPlane := ts_GsnAddr(ggsn_ip_sign),
			ggsn_addr_traffic := ts_GsnAddr(ggsn_ip_data),
			alt_ggsn_addr_controlPane := omit,
			alt_ggsn_addr_traffic := omit,
			qualityOfServiceProfile := ts_QosDefault,
			commonFlags := omit,
			aPN_Restriction := omit,
			mS_InfoChangeReportingAction := omit,
			bearerControlMode := omit,
			evolvedAllocationRetentionPriorityI := omit,
			extendedCommonFlag := omit,
			csg_information_reporting_action := omit,
			aPN_AMBR := omit,
			gGSN_BackOffTime := omit,
			private_extension_gtpc := omit
		}
	}

	template Gtp1cUnitdata ts_GTPC_CreatePdpResp(GtpPeer peer, uint16_t seq, OCT4 teid,
						 OCT1 cause,
						 OCT4 teid_ctrl, OCT4 teid_data,
						 BIT4 nsapi, octetstring ggsn_ip_sign,
						 octetstring ggsn_ip_data, OCT4 chg_id,
						 template EndUserAddress eua := omit,
						 template Recovery_gtpc recovery := omit,
						 template ProtConfigOptions pco := omit) := {
		peer := peer,
		gtpc := ts_GTP1C_PDU(createPDPContextResponse, teid,
					valueof(ts_CreatePdpRespPDU(cause, teid_data, teid_ctrl, nsapi,
								ggsn_ip_sign, ggsn_ip_data, chg_id,
								eua, recovery, pco)), seq)
	}

	/* PCO send base template */
	template ProtConfigOptions ts_PCO := {
		type_gtpc := '84'O,
		lengthf := 0,
		configProtocol := '000'B,
		spare := '0000'B,
		extension0 := '1'B,
		protocols := {}
	}
	/* PCO receive base template */
	template ProtConfigOptions tr_PCO := {
		type_gtpc := '84'O,
		lengthf := ?,
		configProtocol := '000'B,
		spare := ?,
		extension0 := '1'B,
		protocols := {}
	}

	template ProtConfigOptions ts_PCO_IPv6_DNS modifies ts_PCO := {
		protocols := {
			{ protocolID := '0003'O, lengthProtoID := 0, protoIDContents := ''O }
		}
	}
	template ProtConfigOptions tr_PCO_IPv6_DNS_resp(template OCT16 contents) modifies tr_PCO := {
		protocols := {
			*, { protocolID := '0003'O, lengthProtoID := 16, protoIDContents := contents }, *
		}
	}

	template ProtConfigOptions ts_PCO_IPv4_DNS_IPCP modifies ts_PCO := {
		protocols := {
			/* dummy PAP entry to check if our parser in the GGSN can properly iterate over
			 * the list of protocols, see Change-Id Icc2e6716c33d78d3c3e000f529806228d8aa155e */
			{ protocolID := 'C023'O, lengthProtoID := 0, protoIDContents := ''O },
			{ protocolID := '8021'O, lengthProtoID := 16, protoIDContents :=
								enc_IpcpPacket(valueof(ts_IPCP_ReqDNS)) }
		}
	}

	template ProtConfigOptions ts_PCO_IPv4_PRI_DNS_IPCP modifies ts_PCO := {
		protocols := {
			/* dummy PAP entry to check if our parser can cope with a single primary DNS entry
			 * see Change-Id Icffde89f9bc5d8fcadf6e2dd6c0b4de03440edd5 and OS#3288 */
			{ protocolID := 'C023'O, lengthProtoID := 0, protoIDContents := ''O },
			{ protocolID := '8021'O, lengthProtoID := 16, protoIDContents :=
								enc_IpcpPacket(valueof(ts_IPCP_ReqDNS_Primary)) }
		}
	}
	template ProtConfigOptions ts_PCO_IPv4_SEC_DNS_IPCP modifies ts_PCO := {
		protocols := {
			/* dummy PAP entry to check if our parser can cope with a single secondary DNS entry
			 * see Change-Id Icffde89f9bc5d8fcadf6e2dd6c0b4de03440edd5 and OS#3288 */
			{ protocolID := 'C023'O, lengthProtoID := 0, protoIDContents := ''O },
			{ protocolID := '8021'O, lengthProtoID := 16, protoIDContents :=
								enc_IpcpPacket(valueof(ts_IPCP_ReqDNS_Secondary)) }
		}
	}
	template ProtConfigOptions ts_PCO_IPv4_SEPARATE_DNS_IPCP modifies ts_PCO := {
		protocols := {
			/* dummy PAP entry to check if our parser can cope with a primary and secondary DNS
			 * in separate IPCP containers OS#3381 */
			{ protocolID := 'C023'O, lengthProtoID := 0, protoIDContents := ''O },
			{ protocolID := '8021'O, lengthProtoID := 16, protoIDContents :=
								enc_IpcpPacket(valueof(ts_IPCP_ReqDNS_Primary)) },
			{ protocolID := '8021'O, lengthProtoID := 16, protoIDContents :=
								enc_IpcpPacket(valueof(ts_IPCP_ReqDNS_Secondary)) }
		}
	}

	template ProtocolElement tr_PCO_Proto(OCT2 prot_id) := {
		protocolID := prot_id,
		lengthProtoID := ?,
		protoIDContents := ?
	}
	template ProtocolElement ts_PCOelem_PAP_broken := {
		protocolID := 'C023'O,
		lengthProtoID := 60,
		/* PPP Password Authentication Protocol containing incorrect Peer-Id-Length set to 4 (6-7 should be the valid one), see OS#3914. */
		protoIDContents := '0100003c'O & '0444435338323700bc1c08087c1508083e00790000150808fd06000001000000000000000000000000000000000000000000000000000000'O
	}
	template ProtConfigOptions ts_PCO_PAP_IPv4_DNS modifies ts_PCO := {
		protocols := {
			ts_PCOelem_PAP_broken,
			{ protocolID := '8021'O, lengthProtoID := 16, protoIDContents := enc_IpcpPacket(valueof(ts_IPCP_ReqDNS)) }
		}
	}
	template ProtConfigOptions tr_PCO_Contains(OCT2 prot_id) modifies tr_PCO := {
		protocols := { *, tr_PCO_Proto(prot_id), * }
	}

	template ProtConfigOptions ts_PCO_IPv4_DNS_CONT modifies ts_PCO := {
		protocols := {
			{ protocolID := '000d'O, lengthProtoID := 0, protoIDContents := ''O }
		}
	}
	template ProtConfigOptions tr_PCO_IPv4_DNS_CONT_resp(template OCT4 contents) modifies tr_PCO := {
		protocols := {
			*, { protocolID := '000d'O, lengthProtoID := 4, protoIDContents := contents }, *
		}
	}

	/* extract a given protocol payload from PCO */
	function f_PCO_extract_proto(ProtConfigOptions pco, OCT2 protocol, integer nth_match := 1) return octetstring {
		var integer i;
		var integer num_matches := 0;
		for (i := 0; i < lengthof(pco.protocols); i := i + 1) {
			if (pco.protocols[i].protocolID == protocol) {
				num_matches := num_matches + 1;
				if (num_matches == nth_match) {
					return pco.protocols[i].protoIDContents;
				}
			}
		}
		setverdict(fail, "Could not extract protocol payload from protocol ", protocol);
		mtc.stop;
		return ''O;
	}

	template IpcpPacket tr_IPCP(template LcpCode code, template uint8_t identifier,
				    template IpcpOptionList opts) := {
		code := code,
		identifier := identifier,
		len := ?,
		options := opts
	}
	template IpcpOption tr_IPCP_PrimaryDns(template OCT4 addr) := {
		code := IPCP_OPT_PrimaryDNS,
		len := 6,
		data := addr
	}
	template IpcpOption tr_IPCP_SecondaryDns(template OCT4 addr) := {
		code := IPCP_OPT_SecondaryDNS,
		len := 6,
		data := addr
	}
	template IpcpPacket tr_IPCP_Ack_DNS(template uint8_t identifier := ?, template OCT4 dns1 := ?,
					    template OCT4 dns2 := ?) :=
		tr_IPCP(LCP_Configure_Ack, identifier,
				{ *, tr_IPCP_PrimaryDns(dns1), *, tr_IPCP_SecondaryDns(dns2), * });

	template IpcpPacket ts_IPCP(LcpCode code, uint8_t identifier, template IpcpOptionList opts) := {
		code := code,
		identifier := identifier,
		len := 0,	/* overwritten */
		options := opts
	}
	template IpcpPacket ts_IPCP_ReqDNS(uint8_t identifier := 0) :=
		ts_IPCP(LCP_Configure_Request, identifier,
			{ tr_IPCP_PrimaryDns('00000000'O), tr_IPCP_SecondaryDns('00000000'O) });

	template IpcpPacket ts_IPCP_ReqDNS_Primary(uint8_t identifier := 0) :=
		ts_IPCP(LCP_Configure_Request, identifier,
			{ tr_IPCP_PrimaryDns('00000000'O) });
	template IpcpPacket ts_IPCP_ReqDNS_Secondary(uint8_t identifier := 0) :=
		ts_IPCP(LCP_Configure_Request, identifier,
			{ tr_IPCP_SecondaryDns('00000000'O) });

	function f_teardown_ind_IE(in template (omit) BIT1 ind) return template (omit) TearDownInd {
		if (istemplatekind(ind, "omit")) {
			return omit;
		}
		var TearDownInd ret := {
			type_gtpc := '13'O,
			tdInd := valueof(ind),
			spare:= '0000000'B
		}
		return ret;
	}

	template GTPC_PDUs ts_DeletePdpPDU(BIT4 nsapi, template (omit) BIT1 teardown_ind) := {
		deletePDPContextRequest := {
			cause := omit,
			tearDownIndicator := f_teardown_ind_IE(teardown_ind),
			nsapi := {
				type_gtpc := '14'O,
				nsapi := nsapi,
				unused := '0000'B
			},
			protConfigOptions := omit,
			userLocationInformation := omit,
			mS_TimeZone := omit,
			extendedCommonFlags := omit,
			uLI_Timestamp := omit,
			private_extension_gtpc := omit
		}
	}

	template Gtp1cUnitdata ts_GTPC_DeletePDP(GtpPeer peer, uint16_t seq, OCT4 teid,
						 BIT4 nsapi, template (omit) BIT1 teardown_ind) := {
		peer := peer,
		gtpc := ts_GTP1C_PDU(deletePDPContextRequest, teid,
					valueof(ts_DeletePdpPDU(nsapi, teardown_ind)), seq)
	}

	template GTPC_PDUs ts_DeletePdpRespPDU(OCT1 cause,
						template ProtConfigOptions pco := omit) := {
		deletePDPContextResponse := {
			cause := { '00'O, cause },
			protConfigOptions := pco,
			userLocationInformation := omit,
			mS_TimeZone := omit,
			uLI_Timestamp := omit,
			private_extension_gtpc := omit
		}
	}

	template Gtp1cUnitdata ts_GTPC_DeletePdpResp(GtpPeer peer, uint16_t seq, OCT4 teid,
						OCT1 cause,
						template ProtConfigOptions pco := omit) := {
		peer := peer,
		gtpc := ts_GTP1C_PDU(deletePDPContextResponse, teid,
					valueof(ts_DeletePdpRespPDU(cause, pco)), seq)
	}


	/* GTP-C RIM */

	template (value) RIM_Application_Identity_GTPC ts_GTPC_RIM_Application_Identity(OCT1 app_id) := {
		 iEI := '4B'O,
		 ext := '1'B,
		 lengthIndicator := {
			length1 := 1
		 },
		 rIMApplicationIdentity := app_id
	}
	/* 3GPP TS 48.018 11.3.62 */
	template (value) RIM_Sequence_Number_GTPC ts_GTPC_RIM_Sequence_Number(integer seq) := {
		 iEI := '4C'O,
		 ext := '1'B,
		 lengthIndicator := {
			length1 := 4
		 },
		 rIMSequenceNumber := int2oct(seq, 4)
	}
	template (value) RIM_PDU_Indications_GTPC ts_GTPC_RIM_PDU_Indications(boolean ack, BIT3 type_ext) := {
		 iEI := '4F'O,
		 ext := '1'B,
		 lengthIndicator := {
			length1 := 1
		 },
		 ack := bool2bit(ack),
		 pDU_Type_Extension := type_ext,
		 reserved := '0000'B
	}
	/* 3GPP TS 48.018 11.3.67 */
	template (value) RIM_Protocol_Version_Number_GTPC ts_GTPC_RIM_Protocol_Version_Number(integer ver) := {
		 iEI := '55'O,
		 ext := '1'B,
		 lengthIndicator := {
			length1 := 1
		 },
		 rIMProtocolVersionNumber := int2oct(ver, 1)
	}
	function tr_GTPC_Cell_Identifier_V(template GTP_CellId cid) return template Cell_Identifier_V_GTPC {
		var template Cell_Identifier_V_GTPC ret := {
			mccDigit1 := ?,
			mccDigit2 := ?,
			mccDigit3 := ?,
			mncDigit3 := ?,
			mncDigit1 := ?,
			mncDigit2 := ?,
			lac := ?,
			rac := ?,
			cI_value := ?
		}
		if (istemplatekind(cid, "omit")) {
			return omit;
		} else if (istemplatekind(cid, "*")) {
			return *;
		} else if (istemplatekind(cid, "?")) {
			return ?;
		}
		if (isvalue(cid) and isvalue(cid.ra_id) and isvalue(cid.ra_id.lai)) {
			if (isvalue(cid.ra_id.lai.mcc_mnc)) {
				ret.mccDigit1 := cid.ra_id.lai.mcc_mnc[0];
				ret.mccDigit2 := cid.ra_id.lai.mcc_mnc[1];
				ret.mccDigit3 := cid.ra_id.lai.mcc_mnc[2];
				ret.mncDigit3 := cid.ra_id.lai.mcc_mnc[3];
				ret.mncDigit1 := cid.ra_id.lai.mcc_mnc[4];
				ret.mncDigit2 := cid.ra_id.lai.mcc_mnc[5];
			}
			if (isvalue(cid.ra_id.lai.lac)) {
				ret.lac := f_oct_or_wc(cid.ra_id.lai.lac, 2);
			}
		}
		if (isvalue(cid) and isvalue(cid.ra_id)) {
			ret.rac := f_oct_or_wc(cid.ra_id.rac, 1);
		}
		if (isvalue(cid)) {
			ret.cI_value := f_oct_or_wc(cid.cell_id, 2);
		}
		return ret;
	}
	template (value) Cell_Identifier_V_GTPC ts_GTPC_Cell_Identifier_V(GTP_CellId cid) := {
		mccDigit1 := cid.ra_id.lai.mcc_mnc[0],
		mccDigit2 := cid.ra_id.lai.mcc_mnc[1],
		mccDigit3 := cid.ra_id.lai.mcc_mnc[2],
		mncDigit3 := cid.ra_id.lai.mcc_mnc[3],
		mncDigit1 := cid.ra_id.lai.mcc_mnc[4],
		mncDigit2 := cid.ra_id.lai.mcc_mnc[5],
		lac := int2oct(cid.ra_id.lai.lac, 2),
		rac := int2oct(cid.ra_id.rac, 1),
		cI_value := int2oct(cid.cell_id, 2)
	}
	template RIM_Routing_Address_GTPC t_GTPC_RIM_Routing_Address_cid(GTP_CellId cid) := {
		 cell_Identifier := ts_GTPC_Cell_Identifier_V(cid)
	}
	function tr_GTPC_ENB_Identifier(template GTP_CellId cid, template integer tac, template octetstring gnbid) return template ENB_Identifier {
		var template ENB_Identifier ret := {
			mccDigit1 := ?,
			mccDigit2 := ?,
			mccDigit3 := ?,
			mncDigit3 := ?,
			mncDigit1 := ?,
			mncDigit2 := ?,
			tAC := ?,
			globalENB_ID := ?
		}
		if (istemplatekind(cid, "omit") and istemplatekind(tac, "omit") and istemplatekind(gnbid, "omit")) {
			return omit;
		} else if (istemplatekind(cid, "*") and istemplatekind(tac, "*") and istemplatekind(gnbid, "*")) {
			return *;
		} else if (istemplatekind(cid, "?") and istemplatekind(tac, "?") and istemplatekind(gnbid, "?")) {
			return ?;
		}
		if (isvalue(cid) and isvalue(cid.ra_id) and isvalue(cid.ra_id.lai)) {
			if (isvalue(cid.ra_id.lai.mcc_mnc)) {
				ret.mccDigit1 := cid.ra_id.lai.mcc_mnc[0];
				ret.mccDigit2 := cid.ra_id.lai.mcc_mnc[1];
				ret.mccDigit3 := cid.ra_id.lai.mcc_mnc[2];
				ret.mncDigit3 := cid.ra_id.lai.mcc_mnc[3];
				ret.mncDigit1 := cid.ra_id.lai.mcc_mnc[4];
				ret.mncDigit2 := cid.ra_id.lai.mcc_mnc[5];
			}
		}
		if (isvalue(tac)) {
			ret.tAC := int2oct(valueof(tac), 2);
		}
		if (isvalue(gnbid)) {
			ret.globalENB_ID := gnbid;
		}

		return ret;
	}
	template (value) ENB_Identifier ts_GTPC_ENB_Identifier(GTP_CellId cid, integer tac, octetstring gnbid) := {
		mccDigit1 := cid.ra_id.lai.mcc_mnc[0],
		mccDigit2 := cid.ra_id.lai.mcc_mnc[1],
		mccDigit3 := cid.ra_id.lai.mcc_mnc[2],
		mncDigit3 := cid.ra_id.lai.mcc_mnc[3],
		mncDigit1 := cid.ra_id.lai.mcc_mnc[4],
		mncDigit2 := cid.ra_id.lai.mcc_mnc[5],
		tAC := int2oct(tac, 2),
		globalENB_ID := gnbid
	}
	template RIM_Routing_Address_GTPC t_GTPC_RIM_Routing_Address_enbid(GTP_CellId cid, integer tac, octetstring gnbid) := {
		 eNB_Identifier := ts_GTPC_ENB_Identifier(cid, tac, gnbid)
	}
	template RIM_Routing_Information_GTPC
	tr_GTPC_RIM_Routing_Information(HEX1 addr_discr, template RIM_Routing_Address_GTPC addr) := {
		iEI := '54'O,
		ext := '1'B,
			lengthIndicator := {
				length1 := ?
		},
		rIMRoutingAddressDiscriminator := addr_discr,
		spare := '0'H,
		rIM_Routing_Address := addr
	}
	template (value) RIM_Routing_Information_GTPC
	ts_GTPC_RIM_Routing_Information(HEX1 addr_discr, template (value) RIM_Routing_Address_GTPC addr) := {
		iEI := '54'O,
		ext := '1'B,
			lengthIndicator := {
				length1 := 0 /* overwritten */
		},
		rIMRoutingAddressDiscriminator := addr_discr,
		spare := '0'H,
		rIM_Routing_Address := addr
	}
	/* 3GPP TS 48.018 11.3.63.1.1 */
	template RAN_Information_Request_Application_Container_NACC_GTPC
	tr_GTPC_RAN_Information_Request_Application_Container_NACC(template GTP_CellId cid) := {
		iEI := '4D'O,
		ext := '1'B,
		lengthIndicator := {
			length1 := ?
		},
		reporting_Cell_Identifier := tr_GTPC_Cell_Identifier_V(cid)
	}
	template (value) RAN_Information_Request_Application_Container_NACC_GTPC
	ts_GTPC_RAN_Information_Request_Application_Container_NACC(GTP_CellId cid) := {
		iEI := '4D'O,
		ext := '1'B,
		lengthIndicator := {
			length1 := 0 /* overwritten */
		},
		reporting_Cell_Identifier := ts_GTPC_Cell_Identifier_V(cid)
	}
	/* 3GPP TS 48.018 11.3.63.1 */
	template RAN_Information_Request_Application_Container_GTPC
	tru_GTPC_RAN_Information_Request_Application_Container_NACC(template GTP_CellId cid) := {
		nacc := tr_GTPC_RAN_Information_Request_Application_Container_NACC(cid)
	}
	template (value) RAN_Information_Request_Application_Container_GTPC
	tsu_GTPC_RAN_Information_Request_Application_Container_NACC(GTP_CellId cid) := {
		nacc := ts_GTPC_RAN_Information_Request_Application_Container_NACC(cid)
	}
	/* 3GPP TS 48.018 11.3.63.2.1 */
	template RAN_Information_Application_Container_NACC_GTPC
	tr_GTPC_RAN_Information_Application_Container_NACC(template GTP_CellId cid, boolean psi_type, integer si_psi_num, octetstring si_psi) := {
		 iEI := '4E'O,
		 ext := '1'B,
		 lengthIndicator := {
			length1 := ?
		 },
		 reporting_Cell_Identifier := tr_GTPC_Cell_Identifier_V(cid),
		 typeBit := bool2bit(psi_type),
		 number_of_SI_PSI := int2bit(si_psi_num, 7),
		 sI_PSI := si_psi
	}
	template (value) RAN_Information_Application_Container_NACC_GTPC
	ts_GTPC_RAN_Information_Application_Container_NACC(GTP_CellId cid, boolean psi_type, integer si_psi_num, octetstring si_psi) := {
		 iEI := '4E'O,
		 ext := '1'B,
		 lengthIndicator := {
			length1 := 0 /* overwritten */
		 },
		 reporting_Cell_Identifier := ts_GTPC_Cell_Identifier_V(cid),
		 typeBit := bool2bit(psi_type),
		 number_of_SI_PSI := int2bit(si_psi_num, 7),
		 sI_PSI := si_psi
	}

	/* RAN_Information_Request */
	template (value) RAN_Information_Request_RIM_Container_GTPC
	ts_GTPC_RAN_Information_Request_RIM_Container(template (value) RIM_Application_Identity_GTPC app_id,
						      template (value) RIM_Sequence_Number_GTPC seq,
						      template (value) RIM_PDU_Indications_GTPC ind,
						      template (omit) RIM_Protocol_Version_Number_GTPC ver := omit,
						      template (omit) RAN_Information_Request_Application_Container_GTPC app_cont := omit,
						      template (omit) SON_TransferApplicationIdentity son_app_id := omit) := {
		iEI := '57'O,
		ext := '1'B,
		lengthIndicator := {
			length1 := 0 /* overwritten */
		},
		rIM_Application_Identity := app_id,
		rIM_Sequence_Number := seq,
		rIM_PDU_Indications := ind,
		rIM_Protocol_Version_Number := ver,
		application_Container := app_cont,
		sON_TransferApplicationIdentity := son_app_id
	}
	template (value) PDU_BSSGP_RAN_INFORMATION_REQUEST_GTPC
	ts_GTPC_RAN_Information_Request(template (value) RIM_Routing_Information_GTPC dest,
					template (value) RIM_Routing_Information_GTPC src,
					template (value) RAN_Information_Request_RIM_Container_GTPC  cont) := {
		bssgpPduType := '71'O,
		destination_Cell_Identifier := dest,
		source_Cell_Identifier := src,
		rIM_Container := cont
	}
	template (value) RANTransparentContainer ts_RANTransparentContainer_RAN_INFO_REQ(template (value) PDU_BSSGP_RAN_INFORMATION_REQUEST_GTPC pdu) := {
		type_gtpc := '90'O,
		lengthf := 0, /* FIXME */
		rANTransparentContainerField := {
			pDU_BSSGP_RAN_INFORMATION_REQUEST := pdu
		}
	}

	/* RAN_Information */
	template ApplContainer_or_ApplErrContainer_NACC_GTPC
	tru_GTPC_ApplContainer_NACC(GTP_CellId cid, boolean psi_type, integer si_psi_num, octetstring si_psi) := {
		application_Container := tr_GTPC_RAN_Information_Application_Container_NACC(cid, psi_type, si_psi_num, si_psi)
	}
	template (value) ApplContainer_or_ApplErrContainer_NACC_GTPC
	tsu_GTPC_ApplContainer_NACC(GTP_CellId cid, boolean psi_type, integer si_psi_num, octetstring si_psi) := {
		application_Container := ts_GTPC_RAN_Information_Application_Container_NACC(cid, psi_type, si_psi_num, si_psi)
	}
	template ApplContainer_or_ApplErrContainer_GTPC
	tru_GTPC_ApplContainer_or_ApplErrContainer_NACC(template ApplContainer_or_ApplErrContainer_NACC_GTPC cont) := {
		nacc := cont
	}
	template (value) ApplContainer_or_ApplErrContainer_GTPC
	tsu_GTPC_ApplContainer_or_ApplErrContainer_NACC(template (value) ApplContainer_or_ApplErrContainer_NACC_GTPC cont) := {
		nacc := cont
	}
	template RAN_Information_RIM_Container_GTPC
	tr_GTPC_RAN_Information_RIM_Container(template RIM_Application_Identity_GTPC app_id,
					      template RIM_Sequence_Number_GTPC seq,
					      template RIM_PDU_Indications_GTPC ind,
					      template RIM_Protocol_Version_Number_GTPC ver := omit,
					      template ApplContainer_or_ApplErrContainer_GTPC app_cont := omit,
					      template SON_TransferApplicationIdentity son_app_id := omit) := {
		iEI := '58'O,
		ext := '1'B,
		lengthIndicator := {
			length1 := ?
		},
		rIM_Application_Identity := app_id,
		rIM_Sequence_Number := seq,
		rIM_PDU_Indications := ind,
		rIM_Protocol_Version_Number := ver,
		applContainer_or_ApplErrContainer := app_cont,
		sON_TransferApplicationIdentity := son_app_id
	}
	template (value) RAN_Information_RIM_Container_GTPC
	ts_GTPC_RAN_Information_RIM_Container(template (value) RIM_Application_Identity_GTPC app_id,
						      template (value) RIM_Sequence_Number_GTPC seq,
						      template (value) RIM_PDU_Indications_GTPC ind,
						      template (omit) RIM_Protocol_Version_Number_GTPC ver := omit,
						      template (omit) ApplContainer_or_ApplErrContainer_GTPC app_cont := omit,
						      template (omit) SON_TransferApplicationIdentity son_app_id := omit) := {
		iEI := '58'O,
		ext := '1'B,
		lengthIndicator := {
			length1 := 0 /* overwritten */
		},
		rIM_Application_Identity := app_id,
		rIM_Sequence_Number := seq,
		rIM_PDU_Indications := ind,
		rIM_Protocol_Version_Number := ver,
		applContainer_or_ApplErrContainer := app_cont,
		sON_TransferApplicationIdentity := son_app_id
	}
	template PDU_BSSGP_RAN_INFORMATION_GTPC
	tr_GTPC_RAN_Information(template RIM_Routing_Information_GTPC dest,
				template RIM_Routing_Information_GTPC src,
				template RAN_Information_RIM_Container_GTPC cont) := {
		bssgpPduType := '70'O,
		destination_Cell_Identifier := dest,
		source_Cell_Identifier := src,
		rIM_Container := cont
	}
	template (value) PDU_BSSGP_RAN_INFORMATION_GTPC
	ts_GTPC_RAN_Information(template (value) RIM_Routing_Information_GTPC dest,
				template (value) RIM_Routing_Information_GTPC src,
				template (value) RAN_Information_RIM_Container_GTPC cont) := {
		bssgpPduType := '70'O,
		destination_Cell_Identifier := dest,
		source_Cell_Identifier := src,
		rIM_Container := cont
	}
	template RANTransparentContainer tr_RANTransparentContainer_RAN_INFO(template PDU_BSSGP_RAN_INFORMATION_GTPC pdu) := {
		type_gtpc := '90'O,
		lengthf := ?,
		rANTransparentContainerField := {
			pDU_BSSGP_RAN_INFORMATION := pdu
		}
	}
	template (value) RANTransparentContainer ts_RANTransparentContainer_RAN_INFO(template (value) PDU_BSSGP_RAN_INFORMATION_GTPC pdu) := {
		type_gtpc := '90'O,
		lengthf := 0, /* overwritten */
		rANTransparentContainerField := {
			pDU_BSSGP_RAN_INFORMATION := pdu
		}
	}

	template RANTransparentContainer tr_RANTransparentContainer(template RANTransparentContainerField rANTransparentContainerField) := {
		type_gtpc := '90'O,
		lengthf := ?,
		rANTransparentContainerField := rANTransparentContainerField
	}
	template (value) RANTransparentContainer ts_RANTransparentContainer(template (value) RANTransparentContainerField rANTransparentContainerField) := {
		type_gtpc := '90'O,
		lengthf := 0, /* overwritten */
		rANTransparentContainerField := rANTransparentContainerField
	}
	template GTPC_PDUs tr_RANInfoRelay(template RANTransparentContainer transparentContainer) := {
		ranInformationRelay := {
			transparentContainer := transparentContainer,
			rIM_RoutingAddress := *,
			rIM_RoutingAddress_Discriminator := *,
			private_extension_gtpc := *
		}
	}
	template (value) GTPC_PDUs ts_RANInfoRelay(template (value) RANTransparentContainer transparentContainer) := {
		ranInformationRelay := {
			transparentContainer := transparentContainer,
			rIM_RoutingAddress := omit,
			rIM_RoutingAddress_Discriminator := omit,
			private_extension_gtpc := omit
		}
	}
	template Gtp1cUnitdata
	tr_GTPC_RANInfoRelay(template GtpPeer peer,
			     template RANTransparentContainer transparentContainer) := {
		peer := peer,
		gtpc := tr_GTP1C_PDU(rANInformationRelay, '00000000'O, tr_RANInfoRelay(transparentContainer))
	}
	template (value) Gtp1cUnitdata
	ts_GTPC_RANInfoRelay(template (value) GtpPeer peer,
			     template (value) RANTransparentContainer transparentContainer) := {
		peer := peer,
		gtpc := ts_GTP1C_PDU(rANInformationRelay, '00000000'O, valueof(ts_RANInfoRelay(transparentContainer)), 0)
	}


	template RAN_Information_Request_RIM_Container_GTPC
	tr_GTPC_RAN_Information_Request_RIM_Container(template RIM_Application_Identity_GTPC app_id := ?,
						      template RIM_Sequence_Number_GTPC seq := ?,
						      template RIM_PDU_Indications_GTPC ind := ?,
						      template RIM_Protocol_Version_Number_GTPC ver := *,
						      template RAN_Information_Request_Application_Container_GTPC app_cont := *,
						      template SON_TransferApplicationIdentity son_app_id := *) := {
		 iEI := '57'O,
		 ext := '1'B,
		 lengthIndicator := {
			length1 := ?
		 },
		 rIM_Application_Identity := app_id,
		 rIM_Sequence_Number := seq,
		 rIM_PDU_Indications := ind,
		 rIM_Protocol_Version_Number := ver,
		 application_Container := app_cont,
		 sON_TransferApplicationIdentity := son_app_id
	}

	/* GTP-U */

	template PDU_GTPU tr_GTP1U_PDU(template OCT1 msg_type, template OCT4 teid, template GTPU_IEs ies := ?) := {
		pn_bit := ?,
		s_bit := ?,
		e_bit := ?,
		spare := ?,
		/* Protocol Type flag (PT) shall be set to '1' in GTP */
		pt := '1'B,
		/* Version shall be set to decimal 1 ('001'). */
		version := '001'B,
		messageType := msg_type,
		lengthf := ?,
		teid := teid,
		opt_part := *,
		gtpu_IEs := ies
	}

	function f_GTPU_s_bit(template (omit) uint16_t seq) return BIT1 {
		if (istemplatekind(seq, "omit")) {
			return '0'B;
		}
		return '1'B;
	}

	function f_GTPU_opt_part(template (omit) uint16_t seq) return template (omit) GTPU_Header_optional_part {
		if (istemplatekind(seq, "omit")) {
			return omit;
		}
		var GTPU_Header_optional_part ret := {
			sequenceNumber := int2oct(valueof(seq), 2),
			npduNumber := '00'O,
			nextExtHeader := '00'O,
			gTPU_extensionHeader_List := omit
		};
		return ret;
	}

	/* generalized GTP-U send template */
	template PDU_GTPU ts_GTP1U_PDU(OCT1 msg_type, template (omit) uint16_t seq, OCT4 teid, GTPU_IEs ies) := {
		/* N-PDU Number flag (PN): the GTP-U header contains a meaningful N-PDU Number field if the PN
		 * flag is set to 1. */
		pn_bit := '0'B,	/* we assume the encoder overwrites this if an optional part is given */
		/* If the Sequence Number flag (S) is set to '1' the sequence number field is present and
		 * meaningful otherwise it is set to '0'. For GTP-U messages Echo Request, Echo Response,
		 * Error Indication and Supported Extension Headers Notification, the S flag shall be set to '1'.
		 *
		 * Note that the caller must ensure that these conditions hold.
		 * The caller can either pass a sequence number (we set s_bit to '1'B) when appropriate,
		 * or may omit the sequence number (we set s_bit to '0'B). */
		s_bit := f_GTPU_s_bit(seq),
		/* Extension header presence */
		e_bit := '0'B,
		spare := '0'B,
		/* Protocol Type flag (PT) shall be set to '1' in GTP */
		pt := '1'B,
		/* Version shall be set to decimal 1 ('001'). */
		version := '001'B,
		messageType := msg_type,
		lengthf := 0,	/* we assume encoder overwrites this */
		teid := teid,
		opt_part := f_GTPU_opt_part(seq),
		gtpu_IEs := ies
	}

	template Gtp1uUnitdata tr_GTPU_MsgType(template GtpPeer peer, template OCT1 msg_type, template OCT4 teid) := {
		peer := peer,
		gtpu := tr_GTP1U_PDU(msg_type, teid)
	}


	/* template matching reception of GTP-U echo-request */
	template Gtp1uUnitdata tr_GTPU_PING(template GtpPeer peer) := tr_GTPU_MsgType(peer, echoRequest, '00000000'O);

	/* template matching reception of GTP-U GPDU */
	template GTPU_IEs t_GPDU(template octetstring data) := {
		g_PDU_IEs := {
			data := data
		}
	}
	template Gtp1uUnitdata tr_GTPU_GPDU(template GtpPeer peer, template OCT4 teid, template octetstring data := ?) := {
		peer := peer,
		gtpu := tr_GTP1U_PDU('FF'O, teid, t_GPDU(data))
	}

	template GTPU_IEs ts_UEchoRespPDU(OCT1 restart_counter) := {
		echoResponse_IEs := {
			recovery_gtpu := {
				type_gtpu := '00'O, /* we assume encoder fixes? */
				restartCounter := restart_counter
			},
			private_extension_gtpu := omit
		}
	}

	/* master template for sending a GTP-U echo response */
	template Gtp1uUnitdata ts_GTPU_PONG(GtpPeer peer, uint16_t seq, OCT1 rest_ctr) := {
		peer := peer,
		gtpu := ts_GTP1U_PDU(echoResponse, seq, '00000000'O, valueof(ts_UEchoRespPDU(rest_ctr)))
	}

	template GSNAddress_gtpu ts_UGsnAddr(octetstring ip_addr) := {
		type_gtpu := '85'O,
		lengthf := lengthof(ip_addr),
		gSNAddressValue := ip_addr
	}

	template TeidDataI_gtpu ts_UteidDataI(OCT4 teid) := {
		type_gtpu := '10'O,
		teidDataI := teid
	}

	template GTPU_IEs ts_UErrorIndication(OCT4 teid, octetstring gsn_addr) := {
		errorIndication_IEs := {
			teidDataI_gtpu := ts_UteidDataI(teid),
			gSNAddress_gtpu := ts_UGsnAddr(gsn_addr),
			private_extension_gtpu := omit
		}
	}

	/* master template for sending a GTP-U Error indication */
	template Gtp1uUnitdata ts_GTPU_ErrorIndication(GtpPeer peer, uint16_t seq, OCT4 teid, octetstring gsn_addr) := {
		peer := peer,
		gtpu := ts_GTP1U_PDU('1A'O, seq, '00000000'O, valueof(ts_UErrorIndication(teid, gsn_addr)))
	}

	/* master template for sending a GTP-U user plane data */
	template Gtp1uUnitdata ts_GTP1U_GPDU(GtpPeer peer, template (omit) uint16_t seq, OCT4 teid, octetstring data) := {
		peer := peer,
		gtpu := ts_GTP1U_PDU('FF'O, seq, teid, { g_PDU_IEs := { data := data }})
	}
}