-void gre_print_0(const u_char *, u_int);
-void gre_print_1(const u_char *, u_int);
-void gre_sre_print(u_int16_t, u_int8_t, u_int8_t, const u_char *, u_int);
-void gre_sre_ip_print(u_int8_t, u_int8_t, const u_char *, u_int);
-void gre_sre_asn_print(u_int8_t, u_int8_t, const u_char *, u_int);
+static void gre_print_0(netdissect_options *, const u_char *, u_int);
+static void gre_print_1(netdissect_options *, const u_char *, u_int);
+static int gre_sre_print(netdissect_options *, uint16_t, uint8_t, uint8_t, const u_char *, u_int);
+static int gre_sre_ip_print(netdissect_options *, uint8_t, uint8_t, const u_char *, u_int);
+static int gre_sre_asn_print(netdissect_options *, uint8_t, uint8_t, const u_char *, u_int);