+static int is_broadcast(IPaddr_t ip)
+{
+ static IPaddr_t netmask;
+ static IPaddr_t our_ip;
+ static int env_changed_id;
+ int env_id = get_env_id();
+
+ /* update only when the environment has changed */
+ if (env_changed_id != env_id) {
+ netmask = getenv_IPaddr("netmask");
+ our_ip = getenv_IPaddr("ipaddr");
+
+ env_changed_id = env_id;
+ }
+
+ return (ip == ~0 || /* 255.255.255.255 */
+ ((netmask & our_ip) == (netmask & ip) && /* on the same net */
+ (netmask | ip) == ~0)); /* broadcast to our net */
+}
+
+static int refresh_settings_from_env(void)
+{
+ const char *p;
+ static int env_changed_id;
+ int env_id = get_env_id();
+
+ /* update only when the environment has changed */
+ if (env_changed_id != env_id) {
+ if (getenv("ncip")) {
+ nc_ip = getenv_IPaddr("ncip");
+ if (!nc_ip)
+ return -1; /* ncip is 0.0.0.0 */
+ p = strchr(getenv("ncip"), ':');
+ if (p != NULL) {
+ nc_out_port = simple_strtoul(p + 1, NULL, 10);
+ nc_in_port = nc_out_port;
+ }
+ } else
+ nc_ip = ~0; /* ncip is not set, so broadcast */
+
+ p = getenv("ncoutport");
+ if (p != NULL)
+ nc_out_port = simple_strtoul(p, NULL, 10);
+ p = getenv("ncinport");
+ if (p != NULL)
+ nc_in_port = simple_strtoul(p, NULL, 10);
+
+ if (is_broadcast(nc_ip))
+ /* broadcast MAC address */
+ memset(nc_ether, 0xff, sizeof(nc_ether));
+ else
+ /* force arp request */
+ memset(nc_ether, 0, sizeof(nc_ether));
+ }
+ return 0;
+}
+
+/**
+ * Called from NetLoop in net/net.c before each packet
+ */