if_primary_addr
in_addr_t if_primary_addr(struct iface *);
ictl.addr.v4.s_addr = if_primary_addr(ei->iface);
mreq.imr_interface.s_addr = if_primary_addr(iface);
mreq.imr_interface.s_addr = if_primary_addr(iface);
addr = if_primary_addr(iface);
if_primary_addr(nbr->ei->iface)) {
ip_hdr.ip_src.s_addr = if_primary_addr(iface);