hostapd: add support for specifying the FILS DHCP server

The 'fils_dhcp' option can be set to '*' in order to autodetect the DHCP server
For proto=dhcp networks, the discovered dhcp server will be used
For all other networks, udhcpc is called to discover the address

Signed-off-by: Felix Fietkau <nbd@nbd.name>

package/network/services/hostapd/Makefile

@@ -601,6 +601,7 @@ endef
 
 define Package/hostapd-common/install
 	$(INSTALL_DIR) $(1)/etc/capabilities $(1)/etc/rc.button $(1)/etc/hotplug.d/ieee80211 $(1)/etc/init.d $(1)/lib/netifd  $(1)/usr/share/acl.d
+	$(INSTALL_BIN) ./files/dhcp-get-server.sh $(1)/lib/netifd/dhcp-get-server.sh
 	$(INSTALL_DATA) ./files/hostapd.sh $(1)/lib/netifd/hostapd.sh
 	$(INSTALL_BIN) ./files/wpad.init $(1)/etc/init.d/wpad
 	$(INSTALL_BIN) ./files/wps-hotplug.sh $(1)/etc/rc.button/wps

package/network/services/hostapd/files/dhcp-get-server.sh

@@ -0,0 +1,2 @@
+#!/bin/sh
+[ "$1" = bound ] && echo "$serverid"

package/network/services/hostapd/files/hostapd.sh

@@ -370,6 +370,7 @@ hostapd_common_add_bss_config() {
 	config_add_string eap_user_file ca_cert server_cert private_key private_key_passwd server_id
 
 	config_add_boolean fils
+	config_add_string fils_dhcp
 }
 
 hostapd_set_vlan_file() {
@@ -670,7 +671,7 @@ hostapd_set_bss_options() {
 				ownip radius_client_addr \
 				eap_reauth_period request_cui \
 				erp_domain mobility_domain \
-				fils_realm
+				fils_realm fils_dhcp
 
 			# radius can provide VLAN ID for clients
 			vlan_possible=1
@@ -689,6 +690,19 @@ hostapd_set_bss_options() {
 				append bss_conf "erp_domain=$erp_domain" "$N"
 				append bss_conf "fils_realm=$fils_realm" "$N"
 				append bss_conf "fils_cache_id=$(echo "$fils_realm" | md5sum | head -c 4)" "$N"
+
+				[ "$fils_dhcp" = "*" ] && {
+					json_get_values network network
+					fils_dhcp=
+					for net in $network; do
+						fils_dhcp="$(ifstatus "$net" | jsonfilter -e '@.data.dhcpserver')"
+						[ -n "$fils_dhcp" ] && break
+					done
+
+					[ -z "$fils_dhcp" -a -n "$network_bridge" -a -n "$network_ifname" ] && \
+						fils_dhcp="$(udhcpc -B -n -q -s /lib/netifd/dhcp-get-server.sh -t 1 -i "$network_ifname" 2>/dev/null)"
+				}
+				[ -n "$fils_dhcp" ] && append bss_conf "dhcp_server=$fils_dhcp" "$N"
 			}
 
 			set_default auth_port 1812