config_asterisk.sh: filter out any option or list item with new-line

This is to avoid cases where the uci option is directly pushed into the asterisk config without
checking the value, otherwise the value can contain a newline followed by a malicious asterisk config option+value.
Note that '\n' is allowed in the value of an option or list.

net/asterisk/files/iopsys/lib/voice/config_asterisk.sh

@@ -2046,6 +2046,43 @@ generate_asterisk_config_files() {
 	WORK_DIR=$(mktemp -p /tmp -d)
 	mkdir -p $ASTERISK_CONF_DIR
 
+	# overload option_cb and list_cb to filter "invalid" values
+	# if an "invalid" value is found, the value is removed
+	# this logic is heavily based on functions.sh.
+	# "invalid" values include a new line
+	valid(){
+		[ "${1}" = "${1%%$'\n'*}" ]
+	}
+
+	option_cb(){
+		local option="$1"
+		local value="$2"
+		if ! valid "$value"; then
+			# set the value of the current "invalid" option to "" in ENV
+			config_unset "$CONFIG_SECTION" "$option"
+		fi
+	}
+
+	list_cb(){
+		local option="$1"
+		local value="$2"
+		local current_value new_value
+		if ! valid "$value"; then
+			config_get current_value "$CONFIG_SECTION" "$option" "$value"
+			if [ "$current_value" == "$value" ]; then
+				new_value=""
+			else
+				new_value=${current_value%%$LIST_SEP$value}
+			fi
+			# remove the current "invalid" value from the list
+			config_set "$CONFIG_SECTION" "$option" "$new_value"
+			config_get len "$CONFIG_SECTION" "${option}_LENGTH" 1
+			# remove the "invalid" value from the list
+			config_set "$CONFIG_SECTION" "${option}_LENGTH" $((len-1))
+			config_unset "$CONFIG_SECTION" "${option}_ITEM$len"
+		fi
+	}
+
 	# Load config file
 	echo "Loading UCI config $VOICE_UCI_CONFIG"
 	config_load $VOICE_UCI_CONFIG
@@ -2058,6 +2095,9 @@ generate_asterisk_config_files() {
 		config_load $VOICE_UCI_CONFIG
 	}
 
+	# reset all uci callback functions to avoid issues in later config_load
+	reset_cb
+
 	# Create temporary files from templates
 	echo "Create temporary files"
 	create_temp_files