int dhcp_lease_save(sd_dhcp_lease *lease, const char *lease_file);
int dhcp_lease_load(const char *lease_file, sd_dhcp_lease **ret);
int dhcp_lease_save(sd_dhcp_lease *lease, const char *lease_file);
int dhcp_lease_load(const char *lease_file, sd_dhcp_lease **ret);