Function inp_leave_group

freebsd/netinet/in_mcast.c:2297–2507

* Leave an IPv4 multicast group on an inpcb, possibly with a source. */

 * Leave an IPv4 multicast group on an inpcb, possibly with a source.
 */
static int
inp_leave_group(struct inpcb *inp, struct sockopt *sopt)
{
	struct group_source_req		 gsr;
	struct ip_mreq_source		 mreqs;
	struct rm_priotracker		 in_ifa_tracker;
	sockunion_t			*gsa, *ssa;
	struct ifnet			*ifp;
	struct in_mfilter		*imf;
	struct ip_moptions		*imo;
	struct in_msource		*ims;
	struct in_multi			*inm;
	int				 error;
	bool				 is_final;

	ifp = NULL;
	error = 0;
	is_final = true;

	memset(&gsr, 0, sizeof(struct group_source_req));
	gsa = (sockunion_t *)&gsr.gsr_group;
	gsa->ss.ss_family = AF_UNSPEC;
	ssa = (sockunion_t *)&gsr.gsr_source;
	ssa->ss.ss_family = AF_UNSPEC;

	switch (sopt->sopt_name) {
	case IP_DROP_MEMBERSHIP:
	case IP_DROP_SOURCE_MEMBERSHIP:
		if (sopt->sopt_name == IP_DROP_MEMBERSHIP) {
			error = sooptcopyin(sopt, &mreqs,
			    sizeof(struct ip_mreq),
			    sizeof(struct ip_mreq));
			/*
			 * Swap interface and sourceaddr arguments,
			 * as ip_mreq and ip_mreq_source are laid
			 * out differently.
			 */
			mreqs.imr_interface = mreqs.imr_sourceaddr;
			mreqs.imr_sourceaddr.s_addr = INADDR_ANY;
		} else if (sopt->sopt_name == IP_DROP_SOURCE_MEMBERSHIP) {
			error = sooptcopyin(sopt, &mreqs,
			    sizeof(struct ip_mreq_source),
			    sizeof(struct ip_mreq_source));
		}
		if (error)
			return (error);

		gsa->sin.sin_family = AF_INET;
		gsa->sin.sin_len = sizeof(struct sockaddr_in);
		gsa->sin.sin_addr = mreqs.imr_multiaddr;

		if (sopt->sopt_name == IP_DROP_SOURCE_MEMBERSHIP) {
			ssa->sin.sin_family = AF_INET;
			ssa->sin.sin_len = sizeof(struct sockaddr_in);
			ssa->sin.sin_addr = mreqs.imr_sourceaddr;
		}

		/*