int dhcp_l3_socket(int port, const char *interface, int family);
int dhcp_recv_l3_packet(struct dhcp_packet *packet, int fd);
int dhcpv6_recv_l3_packet(struct dhcpv6_packet **packet, unsigned char *buf,
int dhcp_l3_socket(int port, const char *interface, int family);
int dhcp_recv_l3_packet(struct dhcp_packet *packet, int fd);
int dhcpv6_recv_l3_packet(struct dhcpv6_packet **packet, unsigned char *buf,