Fix panic with parsing empty key

Fixes #6990

CHANGELOG.md

@@ -108,6 +108,7 @@ With this release the systemd configuration files for InfluxDB will use the syst
 - [#7081](https://github.com/influxdata/influxdb/issues/7081): Hardcode auto generated RP names to autogen
 - [#7088](https://github.com/influxdata/influxdb/pull/7088): Fix UDP pointsRx being incremented twice.
 - [#7080](https://github.com/influxdata/influxdb/pull/7080): Ensure IDs can't clash when managing Continuous Queries.
+- [#6990](https://github.com/influxdata/influxdb/issues/6990): Fix panic parsing empty key
 
 ## v0.13.0 [2016-05-12]
 

models/points.go

@@ -401,7 +401,7 @@ func scanMeasurement(buf []byte, i int) (int, int, error) {
 	// Check first byte of measurement, anything except a comma is fine.
 	// It can't be a space, since whitespace is stripped prior to this
 	// function call.
-	if buf[i] == ',' {
+	if i >= len(buf) || buf[i] == ',' {
 		return -1, i, fmt.Errorf("missing measurement")
 	}
 

models/points_test.go

@@ -1864,3 +1864,9 @@ func TestNewPointsRejectsMaxKey(t *testing.T) {
 		t.Fatalf("parse point with max key. got: nil, expected: error")
 	}
 }
+
+func TestParseKeyEmpty(t *testing.T) {
+	if _, _, err := models.ParseKey(""); err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+}