Refactor docs; Add 'ipng_source_tag', add udp listener for nginx-ipng-stats plugin

internal/store/store_test.go

@@ -335,3 +335,45 @@ func TestDimensionLabelASN(t *testing.T) {
 		t.Errorf("DimensionLabel ASN: got %q, want %q", got, "12345")
 	}
 }
+
+// --- SourceTag label encoding, filtering, and DimensionLabel ---
+
+func TestEncodeLabelTupleRoundtripWithSourceTag(t *testing.T) {
+	for _, tag := range []string{"", "direct", "cdn", "tag with spaces"} {
+		orig := Tuple6{Website: "a.com", Prefix: "1.2.3.0/24", URI: "/x", Status: "200", SourceTag: tag}
+		got := LabelTuple(EncodeTuple(orig))
+		if got != orig {
+			t.Errorf("roundtrip mismatch for tag=%q: got %+v, want %+v", tag, got, orig)
+		}
+	}
+}
+
+func TestLabelTupleBackwardCompatNoSourceTag(t *testing.T) {
+	// 6-field label (pre-source_tag snapshot) decodes with SourceTag="".
+	label := "a.com\x001.2.3.0/24\x00/x\x00200\x000\x0012345"
+	got := LabelTuple(label)
+	if got.SourceTag != "" {
+		t.Errorf("expected empty SourceTag for 6-field label, got %q", got.SourceTag)
+	}
+	if got.ASN != 12345 {
+		t.Errorf("expected ASN=12345, got %d", got.ASN)
+	}
+}
+
+func TestMatchesFilterSourceTag(t *testing.T) {
+	tag := "cdn"
+	cf := CompileFilter(&pb.Filter{IpngSourceTag: &tag})
+	if !MatchesFilter(Tuple6{SourceTag: "cdn"}, cf) {
+		t.Fatal("should match equal source_tag")
+	}
+	if MatchesFilter(Tuple6{SourceTag: "direct"}, cf) {
+		t.Fatal("should not match different source_tag")
+	}
+}
+
+func TestDimensionLabelSourceTag(t *testing.T) {
+	got := DimensionLabel(Tuple6{SourceTag: "cdn"}, pb.GroupBy_SOURCE_TAG)
+	if got != "cdn" {
+		t.Errorf("DimensionLabel SOURCE_TAG: got %q, want %q", got, "cdn")
+	}
+}