IMS Support

[anaswarac-dac]

This PR adds IMS call support for UE in SMF.

Note: - During testing with COTS UEs, IMS PDU session release behavior was observed and needs further analysis.

[Copilot]

Pull request overview

This PR introduces IMS-related PDU session modification support in the SMF, including P-CSCF address handling and policy-driven QoS updates that trigger PFCP session modification plus NAS/NGAP modification messaging.

Changes:

• Add UE-facing QoS update handling (QoS rules/flows + N1N2 PDU Session Resource Modify) for SM Policy update notifications.
• Extend PFCP Session Modification to include rule removal (Remove PDR/FAR/QER) and update call sites/tests accordingly.
• Add configurable P-CSCF IPv4/IPv6 info and attempt to include P-CSCF IPv4 in PCO when requested.

Reviewed changes

Copilot reviewed 25 out of 25 changed files in this pull request and generated 19 comments.

Show a summary per file

File	Description
util/qos_convert.go	Adds bitrate normalization helper used when building QER rates.
qos/traffic_control_data.go	Implements concrete change detection for TrafficControlData.
qos/qos_rule.go	Adds QoS rule add/modify/delete building helpers and updates marshaling for delete rules.
qos/qos_flow.go	Adds QoS flow add/modify/delete description building and QoS data change detection.
qos/pcc_rule.go	Implements PCC rule diffing helper logic.
producer/ulcl_procedure.go	Updates PFCP session modification calls to new signature.
producer/sm_pfcp_handling.go	Updates PFCP session modification call to new signature.
producer/pdu_session.go	Updates PFCP session modification call to new signature.
producer/n1n2_data_handler.go	Extends PFCP param struct with removal lists.
producer/datapath.go	Updates PFCP session modification call to new signature.
producer/callback.go	Implements SM Policy Update Notify handling to drive PFCP modify + N1N2 QoS modification.
pfcp/message/send.go	Adds remove PDR/FAR/QER parameters to PFCP session modification send path.
pfcp/message/build.go	Adds Remove PDR/FAR/QER IEs to PFCP Session Modification Request.
pfcp/message/send_test.go	Updates PFCP send test for new signature.
pfcp/message/build_test.go	Updates PFCP build tests for new signature.
factory/config.go	Adds PCSCFInfo configuration struct + YAML field.
config/smfcfg.yaml	Adds example pcscfInfos config values.
context/context.go	Plumbs configured PCSCFInfo into SMF context.
context/pcscf_info.go	Adds context-level PCSCFInfo type.
context/pco.go	Adds protocol option flag for PCSCF IPv4 request.
context/gsm_handler.go	Attempts to detect UE PCSCF request from PCO container list.
context/gsm_build.go	Attempts to add PCSCF IPv4 address into EPCO and builds PDU Session Modification Command.
context/ngap_build.go	Adds PDUSessionResourceModifyRequestTransfer builder + bitrate parsing helper.
context/sm_context.go	Adds additional logging and null-guards in SelectedSessionRule.
context/datapath.go	Adds dedicated QER creation (GBR/MBR) for non-default QoS flows.

---

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[Copilot]

GetPfId now prints warnings/errors to stdout via fmt and returns uint8(id) without applying PacketFilterIdBitmask (IDs are limited to 0-15 per the struct comment). This can both spam stdout and produce invalid packet filter identifiers. Prefer logger.QosLog and return (uint8(id) & PacketFilterIdBitmask).

[Copilot]

BuildAuthorizedQosFlowDescriptions assigns qosFlowUpdate := smPolicyUpdates.QosFlowUpdate before checking smPolicyUpdates for nil, and then inside the nil-check block it still dereferences smPolicyUpdates (e.g., smPolicyUpdates.PccRuleUpdate.del). If smPolicyUpdates is nil this will panic. The function should return early when smPolicyUpdates is nil, and separately guard PccRuleUpdate/del from nil before ranging.

Suggested change

	qosFlowUpdate := smPolicyUpdates.QosFlowUpdate
	hasUpdates := false // Track if any QoS flows were processed
	// ===============================
	// Handle PCC rule deletions if QoS flow updates are nil
	// ===============================
	if smPolicyUpdates == nil || smPolicyUpdates.QosFlowUpdate == nil {
	logger.QosLog.Warn("smPolicyUpdates or QosFlowUpdate is nil, processing PCC rule deletions only")
	for pccRuleID := range smPolicyUpdates.PccRuleUpdate.del {
	logger.QosLog.Infof("Processing deletion for PCC rule ID: %s", pccRuleID)
	qfiVal, err := strconv.Atoi(pccRuleID)
	if err != nil {
	logger.QosLog.Errorf("Invalid QFI string for PCC rule ID '%s': %v", pccRuleID, err)
	continue
	}
	qfi := uint8(qfiVal)
	logger.QosLog.Infof("Deleting QoS Flow Description for QFI=%d (from PCC rule %s)", qfi, pccRuleID)
	// Skip if QFI is zero
	if qfi == 0 {
	logger.QosLog.Warnf("Skipping QoS Flow deletion because QFI=0 for PCC rule ID='%s'", pccRuleID)
	continue
	}
	// Build delete QoS Flow Description
	QFDescriptions.BuildDelQosFlowDescFromQoSDesc(qfi)
	hasUpdates = true
	}
	if hasUpdates {
	logger.QosLog.Infof("Completed building delete QoS flow descriptions for %d PCC rules", len(smPolicyUpdates.PccRuleUpdate.del))
	} else {
	logger.QosLog.Warn("No QoS flow deletions were processed")
	}
	}
	hasUpdates := false // Track if any QoS flows were processed
	// ===============================
	// Handle nil smPolicyUpdates early
	// ===============================
	if smPolicyUpdates == nil {
	logger.QosLog.Warn("smPolicyUpdates is nil, nothing to process")
	return &QFDescriptions
	}
	// ===============================
	// Handle PCC rule deletions if QoS flow updates are nil
	// ===============================
	if smPolicyUpdates.QosFlowUpdate == nil {
	logger.QosLog.Warn("QosFlowUpdate is nil, processing PCC rule deletions only")
	if smPolicyUpdates.PccRuleUpdate != nil && smPolicyUpdates.PccRuleUpdate.del != nil {
	for pccRuleID := range smPolicyUpdates.PccRuleUpdate.del {
	logger.QosLog.Infof("Processing deletion for PCC rule ID: %s", pccRuleID)
	qfiVal, err := strconv.Atoi(pccRuleID)
	if err != nil {
	logger.QosLog.Errorf("Invalid QFI string for PCC rule ID '%s': %v", pccRuleID, err)
	continue
	}
	qfi := uint8(qfiVal)
	logger.QosLog.Infof("Deleting QoS Flow Description for QFI=%d (from PCC rule %s)", qfi, pccRuleID)
	// Skip if QFI is zero
	if qfi == 0 {
	logger.QosLog.Warnf("Skipping QoS Flow deletion because QFI=0 for PCC rule ID='%s'", pccRuleID)
	continue
	}
	// Build delete QoS Flow Description
	QFDescriptions.BuildDelQosFlowDescFromQoSDesc(qfi)
	hasUpdates = true
	}
	if hasUpdates {
	logger.QosLog.Infof("Completed building delete QoS flow descriptions for %d PCC rules", len(smPolicyUpdates.PccRuleUpdate.del))
	} else {
	logger.QosLog.Warn("No QoS flow deletions were processed")
	}
	} else {
	logger.QosLog.Warn("PccRuleUpdate or its delete map is nil, no QoS flow deletions to process")
	}
	// No QoS flow updates to process beyond deletions
	return &QFDescriptions
	}
	qosFlowUpdate := smPolicyUpdates.QosFlowUpdate

[Copilot]

HandleSMPolicyUpdateNotify holds smContext.SMLock across PFCP signaling and the AMF N1N2 call (network I/O + waiting on SBIPFCPCommunicationChan). This can block unrelated SM context operations and may deadlock in the UPF-adapter path where PFCP response handlers also take SMLock. Consider limiting the lock scope to only the shared-state mutations, releasing it before sending PFCP/HTTP requests and waiting for responses.

[Copilot]

BuildPfcpParam selects a single PCC rule key (ruleid) from the SmPolicyDecision.PccRules map and only processes PDRs with that key. If multiple PCC rules/PDRs exist, the rest will be ignored (and in release-only case, only one rule would be removed). This should iterate over all relevant PDR entries (or all keys in the PDR maps) rather than picking one arbitrary map key.

Suggested change

	if dlPDR, ok := ANUPF.DownLinkTunnel.PDR[ruleid]; ok {
	for ruleid, dlPDR := range ANUPF.DownLinkTunnel.PDR {

[Copilot]

BuildQosRules treats PCC rule modifications as creates (OperationCodeCreateNewQoSRule). For existing rule updates this should use a modify operation code (and likely BuildModifyQosRuleFromPccRule) so the UE applies it as a modification rather than a new rule.

Suggested change

	qosRule := BuildAddQoSRuleFromPccRule(pccRuleVal, refQosData, OperationCodeCreateNewQoSRule)
	qosRule := BuildAddQoSRuleFromPccRule(pccRuleVal, refQosData, OperationCodeModifyExistingQoSRuleAndReplaceAllPacketFilters)

[Copilot]

SendPfcpSessionModifyReq always passes nil removePDR/removeFAR/removeQER into SendPfcpSessionModificationRequest. This makes the new teardown/removal lists in pfcpParam ineffective (e.g., BuildPfcpParam's release-only path). Pass pfcpParam.removePDR/removeFAR/removeQER through so PFCP removal IEs are actually sent.

Suggested change

	pfcpParam.pdrList, pfcpParam.farList, pfcpParam.barList, pfcpParam.qerList, nil, nil, nil, ANUPF.UPF.Port)
	pfcpParam.pdrList, pfcpParam.farList, pfcpParam.barList, pfcpParam.qerList, pfcpParam.removePDR, pfcpParam.removeFAR, pfcpParam.removeQER, ANUPF.UPF.Port)

[Copilot]

The PCSCF IPv4 request flag is set when encountering PCSCFReSelectionSupportUL, but the actual container ID for requesting a P-CSCF IPv4 address is PCSCFIPv4AddressRequestUL. As written, a UE that sends PCSCFIPv4AddressRequestUL will still hit the "Didn't Implement" case and not set PCSCFIPv4Request.

[Copilot]

StringToBitRate returns (0, nil) for unsupported/invalid strings and does not trim whitespace after stripping the unit (e.g., "101 Mbps" -> trimSuffix("mbps") yields "101 " which ParseUint fails). This can silently convert rates to 0 and mask errors. Consider trimming spaces after TrimSuffix and returning a non-nil error for unknown/invalid units so callers can handle it explicitly.

Suggested change

	val, err := strconv.ParseUint(strings.TrimSuffix(s, "kbps"), 10, 64)
	if err != nil {
	return 0, err
	}
	return val * 1000, nil
	}
	if strings.HasSuffix(s, "mbps") {
	val, err := strconv.ParseUint(strings.TrimSuffix(s, "mbps"), 10, 64)
	if err != nil {
	return 0, err
	}
	return val * 1000 * 1000, nil
	}
	return 0, nil
	numPart := strings.TrimSpace(strings.TrimSuffix(s, "kbps"))
	val, err := strconv.ParseUint(numPart, 10, 64)
	if err != nil {
	return 0, err
	}
	return val * 1000, nil
	}
	if strings.HasSuffix(s, "mbps") {
	numPart := strings.TrimSpace(strings.TrimSuffix(s, "mbps"))
	val, err := strconv.ParseUint(numPart, 10, 64)
	if err != nil {
	return 0, err
	}
	return val * 1000 * 1000, nil
	}
	return 0, fmt.Errorf("unsupported bitrate format: %q", s)