Fix extended JSON parser for large dates.

GODRIVER-983

Change-Id: I4aa8435fcb39ec866d97a3dc7790a6307c3b92c2

Author: Divjot Arora

bson/bsonrw/extjson_parser_test.go

@@ -716,3 +716,21 @@ func TestExtJSONParserAllTypes(t *testing.T) {
 		t.FailNow()
 	}
 }
+
+func TestExtJSONValue(t *testing.T) {
+	t.Run("Large Date", func(t *testing.T) {
+		val := &extJSONValue{
+			t: bsontype.String,
+			v: "3001-01-01T00:00:00Z",
+		}
+
+		intVal, err := val.parseDateTime()
+		if err != nil {
+			t.Fatalf("error parsing date time: %v", err)
+		}
+
+		if intVal <= 0 {
+			t.Fatalf("expected value above 0, got %v", intVal)
+		}
+	})
+}

bson/bsonrw/extjson_wrappers.go

@@ -203,7 +203,7 @@ func parseDatetimeString(data string) (int64, error) {
 		return 0, fmt.Errorf("invalid $date value string: %s", data)
 	}
 
-	return t.UnixNano() / 1e6, nil
+	return t.Unix()*1e3 + int64(t.Nanosecond())/1e6, nil
 }
 
 func parseDatetimeObject(data *extJSONObject) (d int64, err error) {