#include    <errno.h>

#include    <sys/socket.h>

#define     SA    struct sockaddr

int mcast_unblock_source(int sockfd, const SA *src,

    socklen_t srclen,const SA *grp, socklen_t grplen)

{

#ifdef MCAST_UNBLOCK_SOURCE

    struct group_source_req req;

    req.gsr_interface = ;

    if (grplen > sizeof(req.gsr_group) ||

        srclen > sizeof(req.gsr_source)) {

        errno = EINVAL;

        return -;

    }

    memcpy(&req.gsr_group, grp, grplen);

    memcpy(&req.gsr_source, src, srclen);

    return (setsockopt(sockfd, family_to_level(grp->sa_family),

            MCAST_UNBLOCK_SOURCE, &req, sizeof(req)));

#else

    switch (grp->sa_family) {

#ifdef IP_UNBLOCK_SOURCE

        case AF_INET: {

            struct ip_mreq_source    mreq;

            memcpy(&mreq.imr_multiaddr,

               &((struct sockaddr_in *) grp)->sin_addr,

               sizeof(struct in_addr));

            memcpy(&mreq.imr_sourceaddr,

               &((struct sockaddr_in *) src)->sin_addr,

               sizeof(struct in_addr));

            mreq.imr_interface.s_addr = htonl(INADDR_ANY);

            return(setsockopt(sockfd, IPPROTO_IP,

                   IP_UNBLOCK_SOURCE, &mreq, sizeof(mreq)));

        }

#endif

#ifdef    IPV6

        /* IPv6 source-specific API is MCAST_UNBLOCK_SOURCE */

        case AF_INET6: {}

#endif

        default: {

            errno = EAFNOSUPPORT;

            return(-);

        }

    }

#endif

}