extern void ip_to_string (IPaddr_t x, char *s);
/* Convert a string to ip address */
-extern IPaddr_t string_to_ip(char *s);
+extern IPaddr_t string_to_ip(const char *s);
/* Convert a VLAN id to a string */
extern void VLAN_to_string (ushort x, char *s);
/* Convert a string to a vlan id */
-extern ushort string_to_VLAN(char *s);
+extern ushort string_to_VLAN(const char *s);
/* read a VLAN id from an environment variable */
extern ushort getenv_VLAN(char *);
/* copy a filename (allow for "..." notation, limit length) */
-extern void copy_filename (char *dst, char *src, int size);
+extern void copy_filename (char *dst, const char *src, int size);
/* get a random source port */
extern unsigned int random_port(void);