Whitelist allowed char classes for graphite output (#3473)

plugins/serializers/graphite/graphite_test.go

@@ -8,6 +8,7 @@ import (
 	"time"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 
 	"github.com/influxdata/telegraf/metric"
 )
@@ -468,3 +469,95 @@ func TestTemplate6(t *testing.T) {
 	expS := "localhost.cpu0.us-west-2.cpu.FIELDNAME"
 	assert.Equal(t, expS, mS)
 }
+
+func TestClean(t *testing.T) {
+	now := time.Unix(1234567890, 0)
+	tests := []struct {
+		name        string
+		metric_name string
+		tags        map[string]string
+		fields      map[string]interface{}
+		expected    string
+	}{
+		{
+			"Base metric",
+			"cpu",
+			map[string]string{"host": "localhost"},
+			map[string]interface{}{"usage_busy": float64(8.5)},
+			"localhost.cpu.usage_busy 8.5 1234567890\n",
+		},
+		{
+			"Dot and whitespace in tags",
+			"cpu",
+			map[string]string{"host": "localhost", "label.dot and space": "value with.dot"},
+			map[string]interface{}{"usage_busy": float64(8.5)},
+			"localhost.value_with_dot.cpu.usage_busy 8.5 1234567890\n",
+		},
+		{
+			"Field with space",
+			"system",
+			map[string]string{"host": "localhost"},
+			map[string]interface{}{"uptime_format": "20 days, 23:26"},
+			"", // yes nothing. graphite don't serialize string fields
+		},
+		{
+			"Allowed punct",
+			"cpu",
+			map[string]string{"host": "localhost", "tag": "-_:="},
+			map[string]interface{}{"usage_busy": float64(10)},
+			"localhost.-_:=.cpu.usage_busy 10 1234567890\n",
+		},
+		{
+			"Special conversions to hyphen",
+			"cpu",
+			map[string]string{"host": "localhost", "tag": "/@*"},
+			map[string]interface{}{"usage_busy": float64(10)},
+			"localhost.---.cpu.usage_busy 10 1234567890\n",
+		},
+		{
+			"Special drop chars",
+			"cpu",
+			map[string]string{"host": "localhost", "tag": `\no slash`},
+			map[string]interface{}{"usage_busy": float64(10)},
+			"localhost.no_slash.cpu.usage_busy 10 1234567890\n",
+		},
+		{
+			"Empty tag & value field",
+			"cpu",
+			map[string]string{"host": "localhost"},
+			map[string]interface{}{"value": float64(10)},
+			"localhost.cpu 10 1234567890\n",
+		},
+		{
+			"Unicode Letters allowed",
+			"cpu",
+			map[string]string{"host": "localhost", "tag": "μnicodε_letters"},
+			map[string]interface{}{"value": float64(10)},
+			"localhost.μnicodε_letters.cpu 10 1234567890\n",
+		},
+		{
+			"Other Unicode not allowed",
+			"cpu",
+			map[string]string{"host": "localhost", "tag": "“☢”"},
+			map[string]interface{}{"value": float64(10)},
+			"localhost.___.cpu 10 1234567890\n",
+		},
+		{
+			"Newline in tags",
+			"cpu",
+			map[string]string{"host": "localhost", "label": "some\nthing\nwith\nnewline"},
+			map[string]interface{}{"usage_busy": float64(8.5)},
+			"localhost.some_thing_with_newline.cpu.usage_busy 8.5 1234567890\n",
+		},
+	}
+
+	s := GraphiteSerializer{}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			m, err := metric.New(tt.metric_name, tt.tags, tt.fields, now)
+			assert.NoError(t, err)
+			actual, _ := s.Serialize(m)
+			require.Equal(t, tt.expected, string(actual))
+		})
+	}
+}