#include	"unp.h"intmcast_leave(int sockfd, const SA *sa, socklen_t salen){	switch (sa->sa_family) {	case AF_INET: {		struct ip_mreq		mreq;		memcpy(&mreq.imr_multiaddr,			   &((struct sockaddr_in *) sa)->sin_addr,			   sizeof(struct in_addr));		mreq.imr_interface.s_addr = htonl(INADDR_ANY);		return(setsockopt(sockfd, IPPROTO_IP, IP_DROP_MEMBERSHIP,						  &mreq, sizeof(mreq)));	}#ifdef	IPV6	case AF_INET6: {		struct ipv6_mreq	mreq6;		memcpy(&mreq6.ipv6mr_multiaddr,			   &((struct sockaddr_in6 *) sa)->sin6_addr,			   sizeof(struct in6_addr));		mreq6.ipv6mr_interface = 0;		return(setsockopt(sockfd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP,						  &mreq6, sizeof(mreq6)));	}#endif	default:		errno = EPROTONOSUPPORT;		return(-1);	}}voidMcast_leave(int sockfd, const SA *sa, socklen_t salen){	if (mcast_leave(sockfd, sa, salen) < 0)		err_sys("mcast_leave error");}