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mrouted

/*
 * The mrouted program is covered by the license in the accompanying file
 * named "LICENSE".  Use of the mrouted program represents acceptance of
 * the terms and conditions listed in that file.
 *
 * The mrouted program is COPYRIGHT 1989 by The Board of Trustees of
 * Leland Stanford Junior University.
 */

#include "defs.h"
#include <ifaddrs.h>

/*
 * Query the kernel to find network interfaces that are multicast-capable
 * and install them in the uvifs array.
 */
void
config_vifs_from_kernel()
{
    struct ifaddrs *ifa, *ifap;
    register struct uvif *v;
    register vifi_t vifi;
    u_int32 addr, mask, subnet;
    int flags;

    if (getifaddrs(&ifap) < 0)
	logit(LOG_ERR, errno, "getifaddrs");
    /*
     * Loop through all of the interfaces.
     */
    for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
	/*
	 * Ignore any interface for an address family other than IP.
	 */
	if (!ifa->ifa_addr || ifa->ifa_addr->sa_family != AF_INET)
	    continue;

	/*
	 * Ignore loopback interfaces and interfaces that do not support
	 * multicast.
	 */
	flags = ifa->ifa_flags;
	if ((flags & (IFF_LOOPBACK|IFF_MULTICAST)) != IFF_MULTICAST)
	    continue;

	/*
	 * Perform some sanity checks on the address and subnet, ignore any
	 * interface whose address and netmask do not define a valid subnet.
	 */
	addr = ((struct sockaddr_in *)ifa->ifa_addr)->sin_addr.s_addr;
	mask = ((struct sockaddr_in *)ifa->ifa_netmask)->sin_addr.s_addr;
	subnet = addr & mask;
	if (!inet_valid_subnet(subnet, mask) || (addr != subnet && addr == (subnet & ~mask))) {
	    logit(LOG_WARNING, 0, "ignoring %s, has invalid address (%s) and/or mask (%s)",
		  ifa->ifa_name, inet_fmt(addr, s1, sizeof(s1)), inet_fmt(mask, s2, sizeof(s2)));
	    continue;
	}

	/*
	 * Ignore any interface that is connected to the same subnet as
	 * one already installed in the uvifs array.
	 */
	for (vifi = 0, v = uvifs; vifi < numvifs; ++vifi, ++v) {
	    if (strcmp(v->uv_name, ifa->ifa_name) == 0) {
		logit(LOG_DEBUG, 0, "skipping %s (%s on subnet %s) (alias for vif#%u?)",
			v->uv_name, inet_fmt(addr, s1, sizeof(s1)),
			inet_fmts(subnet, mask, s2, sizeof(s2)), vifi);
		break;
	    }
	    if ((addr & v->uv_subnetmask) == v->uv_subnet ||
		(v->uv_subnet & mask) == subnet) {
		logit(LOG_WARNING, 0, "ignoring %s, same subnet as %s",
		    ifa->ifa_name, v->uv_name);
		break;
	    }
	}
	if (vifi != numvifs) continue;

	/*
	 * If there is room in the uvifs array, install this interface.
	 */
	if (numvifs == MAXVIFS) {
	    logit(LOG_WARNING, 0, "too many vifs, ignoring %s", ifa->ifa_name);
	    continue;
	}
	v  = &uvifs[numvifs];
	zero_vif(v, 0);
	v->uv_lcl_addr    = addr;
	v->uv_subnet      = subnet;
	v->uv_subnetmask  = mask;
	v->uv_subnetbcast = subnet | ~mask;
	strncpy(v->uv_name, ifa->ifa_name, sizeof(v->uv_name));

	if (flags & IFF_POINTOPOINT)
	    v->uv_flags |= VIFF_REXMIT_PRUNES;

	logit(LOG_INFO,0,"installing %s (%s on subnet %s) as vif #%u - rate=%d",
	    v->uv_name, inet_fmt(addr, s1, sizeof(s1)), inet_fmts(subnet, mask, s2, sizeof(s2)),
	    numvifs, v->uv_rate_limit);

	++numvifs;

	/*
	 * If the interface is not yet up, set the vifs_down flag to
	 * remind us to check again later.
	 */
	if (!(flags & IFF_UP)) {
	    v->uv_flags |= VIFF_DOWN;
	    vifs_down = TRUE;
	}
    }

    freeifaddrs(ifap);
}

/**
 * Local Variables:
 *  version-control: t
 *  indent-tabs-mode: t
 *  c-file-style: "ellemtel"
 *  c-basic-offset: 4
 * End:
 */