extern void setsockopt_so_recvbuf(int sock, int size);
extern void setsockopt_so_sendbuf(const int sock, int size);
extern int getsockopt_so_sendbuf(const int sock);
+extern int getsockopt_so_recvbuf(const int sock);
extern int setsockopt_ipv6_pktinfo(int, int);
-extern int setsockopt_ipv6_checksum(int, int);
extern int setsockopt_ipv6_multicast_hops(int, int);
extern int setsockopt_ipv6_unicast_hops(int, int);
extern int setsockopt_ipv6_hoplimit(int, int);