sanitize tag keys

- add tests for edge cases
 - fix typo

bridge_test.go

@@ -66,6 +66,26 @@ func TestHandlePacket(t *testing.T) {
 					labels:     map[string]string{"tag1": "bar", "tag2": "baz", "tag3": ".", "tag4": "."},
 				},
 			},
+		}, {
+			name: "datadog tag extension with # in all keys (as sent by datadog php client)",
+			in:   "foo:100|c|#tag1:bar,#tag2:baz,#tag3,#tag4",
+			out: Events{
+				&CounterEvent{
+					metricName: "foo",
+					value:      100,
+					labels:     map[string]string{"tag1": "bar", "tag2": "baz", "tag3": ".", "tag4": "."},
+				},
+			},
+		}, {
+			name: "datadog tag extension with tags unsupported by prometheus",
+			in:   "foo:100|c|#09digits:0,tag.with.dots,tag_with_empty_value:",
+			out: Events{
+				&CounterEvent{
+					metricName: "foo",
+					value:      100,
+					labels:     map[string]string{"_09digits": "0", "tag_with_dots": ".", "tag_with_empty_value": "."},
+				},
+			},
 		}, {
 			name: "datadog tag extension with sampling",
 			in:   "foo:100|c|@0.1|#tag1:bar,tag2,tag3:baz",

exporter.go

@@ -360,17 +360,25 @@ func (l *StatsDListener) handlePacket(packet []byte, e chan<- Events) {
 						}
 						value /= samplingFactor
 					case '#':
-						networkStats.WithLabelValues("dogstasd_tags").Inc()
-						tags := strings.Split(component[1:], ",")
+						networkStats.WithLabelValues("dogstatsd_tags").Inc()
+						tags := strings.Split(component, ",")
 						for _, t := range tags {
+							t = strings.TrimPrefix(t, "#")
 							kv := strings.Split(t, ":")
+							tag_key := kv[0]
+							tag_key = escapeMetricName(tag_key)
+
+							var tag_value string
 							if len(kv) == 2 {
 								if len(kv[1]) > 0 {
-									labels[kv[0]] = kv[1]
+									tag_value = kv[1]
+								} else {
+									tag_value = "."
 								}
 							} else if len(kv) == 1 {
-								labels[kv[0]] = "."
+								tag_value = "."
 							}
+							labels[tag_key] = tag_value
 						}
 					default:
 						log.Printf("Invalid sampling factor or tag section %s on line %s", components[2], line)