feat: add HasUserLocationInformationNRExtension helper

Add a small NGAP-aware helper that reports whether a given
UserLocationInformationNR carries a protocol extension with the
specified ProtocolIE-ID inside its IEExtensions container.

Generic over the extension ID, so callers can compose it with any
existing or future ProtocolIEID* constant (NRNTN-TAI-Information being
the immediate use case from omec-project/amf#684).

Keeping NGAP-aware inspection helpers in this repo makes the eventual
N2 release uplift easier to scope: all NGAP-touching code lives here.

Signed-off-by: Vinod Patmanathan <vinod.patmanathan@forsway.com>

Author: Vinod Patmanathan

extensions.go

@@ -0,0 +1,25 @@
+// Copyright 2026 Forsway Solutions AB
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package ngap
+
+import "github.com/omec-project/ngap/ngapType"
+
+// HasUserLocationInformationNRExtension reports whether the given
+// UserLocationInformationNR carries a protocol extension with the
+// specified ProtocolIE-ID inside its IEExtensions container.
+//
+// A nil UserLocationInformationNR or a nil IEExtensions container both
+// yield false.
+func HasUserLocationInformationNRExtension(loc *ngapType.UserLocationInformationNR, id int64) bool {
+	if loc == nil || loc.IEExtensions == nil {
+		return false
+	}
+	for _, ext := range loc.IEExtensions.List {
+		if ext.Id.Value == id {
+			return true
+		}
+	}
+	return false
+}

extensions_test.go

@@ -0,0 +1,81 @@
+// Copyright 2026 Forsway Solutions AB
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package ngap_test
+
+import (
+	"testing"
+
+	"github.com/omec-project/ngap"
+	"github.com/omec-project/ngap/ngapType"
+)
+
+func TestHasUserLocationInformationNRExtension(t *testing.T) {
+	tests := []struct {
+		name string
+		loc  *ngapType.UserLocationInformationNR
+		id   int64
+		want bool
+	}{
+		{
+			name: "nil location",
+			loc:  nil,
+			id:   ngapType.ProtocolIEIDNRNTNTAIInformation,
+			want: false,
+		},
+		{
+			name: "nil extensions",
+			loc:  &ngapType.UserLocationInformationNR{},
+			id:   ngapType.ProtocolIEIDNRNTNTAIInformation,
+			want: false,
+		},
+		{
+			name: "empty extension list",
+			loc: &ngapType.UserLocationInformationNR{
+				IEExtensions: &ngapType.ProtocolExtensionContainerUserLocationInformationNRExtIEs{},
+			},
+			id:   ngapType.ProtocolIEIDNRNTNTAIInformation,
+			want: false,
+		},
+		{
+			name: "unrelated extension only",
+			loc:  newNRLocationWithExtensionIDs(42),
+			id:   ngapType.ProtocolIEIDNRNTNTAIInformation,
+			want: false,
+		},
+		{
+			name: "matching extension present",
+			loc:  newNRLocationWithExtensionIDs(ngapType.ProtocolIEIDNRNTNTAIInformation),
+			id:   ngapType.ProtocolIEIDNRNTNTAIInformation,
+			want: true,
+		},
+		{
+			name: "matching extension among several",
+			loc:  newNRLocationWithExtensionIDs(42, 99, ngapType.ProtocolIEIDNRNTNTAIInformation, 150),
+			id:   ngapType.ProtocolIEIDNRNTNTAIInformation,
+			want: true,
+		},
+	}
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			if got := ngap.HasUserLocationInformationNRExtension(tc.loc, tc.id); got != tc.want {
+				t.Errorf("HasUserLocationInformationNRExtension = %v, want %v", got, tc.want)
+			}
+		})
+	}
+}
+
+func newNRLocationWithExtensionIDs(ids ...int64) *ngapType.UserLocationInformationNR {
+	list := make([]ngapType.UserLocationInformationNRExtIEs, 0, len(ids))
+	for _, id := range ids {
+		list = append(list, ngapType.UserLocationInformationNRExtIEs{
+			Id: ngapType.ProtocolExtensionID{Value: id},
+		})
+	}
+	return &ngapType.UserLocationInformationNR{
+		IEExtensions: &ngapType.ProtocolExtensionContainerUserLocationInformationNRExtIEs{
+			List: list,
+		},
+	}
+}