TBT_NAMLEN
if (strncmp(cmd, TBT_DISCOVER_IFACE, TBT_NAMLEN) == 0) {
} else if (strncmp(cmd, TBT_DISCOVER_DOMAIN, TBT_NAMLEN) == 0) {
} else if (strncmp(cmd, TBT_DISCOVER_ROUTER, TBT_NAMLEN) == 0) {