Refined "mac_interface" feature #24

Closes #24

README.rst

@@ -61,7 +61,6 @@ UCI configuration options must go in ``/etc/config/openwisp``.
 - ``verify_ssl``: whether SSL verification must be performed or not, defaults to ``1``
 - ``shared_secret``: shared secret, needed for `Automatic registration`_
 - ``consistent_key``: whether `Consistent key generation`_ is enabled or not, defaults to ``1``
-- ``mac_interface``: which interface to use (if it exists) to catch the MAC address, defaults to ``eth0``
 - ``merge_config``: whether `Merge configuration`_ is enabled or not, defaults to ``1``
 - ``test_config``: whether a new configuration must be tested before being considered applied, defaults to ``1``
 - ``test_script``: custom test script, read more about this feature in `Configuration test`_
@@ -71,6 +70,7 @@ UCI configuration options must go in ``/etc/config/openwisp``.
 - ``capath``: value passed to curl ``--capath`` argument, defaults to ``/etc/ssl/certs``; see also `curl capath argument <https://curl.haxx.se/docs/manpage.html#--capath>`_
 - ``connect_timeout``: value passed to curl ``--connect-timeout`` argument, defaults to ``15``; see `curl connect-timeout argument <https://curl.haxx.se/docs/manpage.html#--connect-timeout>`_
 - ``max_time``: value passed to curl ``--max-time`` argument, defaults to ``30``; see `curl connect-timeout argument <https://curl.haxx.se/docs/manpage.html#-m>`_
+- ``mac_interface``: the interface from which the MAC address is taken when performing automatic registration, defaults to ``eth0``;
 
 Automatic registration
 ----------------------
@@ -95,11 +95,13 @@ even if reset or reflashed.
 The ``key`` is generated consistently with an operation like ``md5sum(mac_address + shared_secret)``;
 this allows the controller application to recognize that an existing device is registering itself again.
 
-Verify that the interface of which you take the mac address is always the same with the mac_interface option.
-Pay attention on virtual interface like bridges and taps.
+The ``mac_interface`` configuration key specifies which interface is used to calculate the mac address,
+this setting defaults to ``eth0``. If no ``eth0`` interface exists, the first non-loopback, non-bridge and non-tap
+interface is used. You won't need to change this setting often, but if you do, ensure you choose a physical
+interface which has constant mac address.
 
-This feature is enabled by default, but must be enabled also in the controller application
-in order to work.
+The "Consistent key generation" feature is enabled by default, but must be enabled also in the
+controller application in order to work.
 
 Merge configuration
 -------------------

openwisp-config/files/openwisp.agent

@@ -11,14 +11,14 @@ while [ -n "$1" ]; do
 		--key) export KEY="$2"; shift;;
 		--shared-secret) export SHARED_SECRET="$2"; shift;;
 		--consistent-key) export CONSISTENT_KEY="$2"; shift;;
-		--mac-interface) export MAC_INTERFACE="$2"; shift;;
 		--merge-config) export MERGE_CONFIG="$2"; shift;;
 		--unmanaged) export UNMANAGED="$2"; shift;;
 		--test-config) export TEST_CONFIG="$2"; shift;;
 		--test-script) export TEST_SCRIPT="$2"; shift;;
 		--connect-timeout) export CONNECT_TIMEOUT="$2"; shift;;
 		--max-time) export MAX_TIME="$2"; shift;;
 		--capath) export CAPATH="$2"; shift;;
+		--mac-interface) export MAC_INTERFACE="$2"; shift;;
 		-*)
 			echo "Invalid option: $1"
 			exit 1
@@ -53,10 +53,10 @@ VERIFY_SSL=${VERIFY_SSL:-1}
 MERGE_CONFIG=${MERGE_CONFIG:-1}
 TEST_CONFIG=${TEST_CONFIG:-1}
 CONSISTENT_KEY=${CONSISTENT_KEY:-1}
-MAC_INTERFACE=${MAC_INTERFACE:-eth0}
 CONNECT_TIMEOUT=${CONNECT_TIMEOUT:-15}
 MAX_TIME=${MAX_TIME:-30}
 CAPATH=${CAPATH:-/etc/ssl/certs}
+MAC_INTERFACE=${MAC_INTERFACE:-eth0}
 WORKING_DIR="/tmp/openwisp"
 BASEURL="$URL/controller"
 CONFIGURATION_ARCHIVE="$WORKING_DIR/configuration.tar.gz"
@@ -102,7 +102,7 @@ register() {
 	local raw=$(ifconfig $MAC_INTERFACE 2&> /dev/null)
 	if [ -z "$raw" ]; then raw=$(ifconfig); fi
 	local macaddr=$(echo "$raw " | egrep -v "^(lo|br-|tap[0-9]+)" | awk '/HWaddr/ { print $5 }' | head -n 1)
-	# use macaddress if hostname is the default one or empty 
+	# use macaddress if hostname is the default one or empty
 	if [ "$hostname" == "OpenWrt" ] || [ "$hostname" == "lede" ] || [ -z "$hostname" ]; then
 		hostname="$macaddr"
 	fi

openwisp-config/files/openwisp.init

@@ -15,22 +15,21 @@ start_service() {
 	key=$(config_get http key)
 	shared_secret=$(config_get http shared_secret)
 	consistent_key=$(config_get http consistent_key)
-	mac_interface=$(config_get http mac_interface)
 	unmanaged=$(config_get http unmanaged)
 	merge_config=$(config_get http merge_config)
 	test_config=$(config_get http test_config)
 	test_script=$(config_get http test_script)
 	connect_timeout=$(config_get http connect_timeout)
 	max_time=$(config_get http max_time)
 	capath=$(config_get http capath)
+	mac_interface=$(config_get http mac_interface)
 	if [ $url ]; then url="--url $url"; fi
 	if [ $interval ]; then interval="--interval $interval"; fi
 	if [ $verify_ssl ]; then verify_ssl="--verify-ssl $verify_ssl"; fi
 	if [ $uuid ]; then uuid="--uuid $uuid"; fi
 	if [ $key ]; then key="--key $key"; fi
 	if [ $shared_secret ]; then shared_secret="--shared-secret $shared_secret"; fi
 	if [ $consistent_key ]; then consistent_key="--consistent-key $consistent_key"; fi
-	if [ $mac_interface ]; then mac_interface="--mac-interface $mac_interface"; fi
 	if [ -n "$unmanaged" ]; then
 		# replace spaces with commas to avoid problems when
 		# passing this arg to procd_set_param command
@@ -43,6 +42,7 @@ start_service() {
 	if [ $connect_timeout ]; then connect_timeout="--connect-timeout $connect_timeout"; fi
 	if [ $max_time ]; then max_time="--max-time $max_time"; fi
 	if [ $capath ]; then capath="--capath $capath"; fi
+	if [ $mac_interface ]; then mac_interface="--mac-interface $mac_interface"; fi
 
 	if [ -z "$url" ]; then
 		logger -s "url is not set, please add it in /etc/config/openwisp" \
@@ -60,8 +60,8 @@ start_service() {
 
 	procd_open_instance
 	procd_set_param command $PROG $url $interval $verify_ssl $uuid $key $shared_secret \
-	                        $consistent_key $mac_interface $unmanaged $merge_config $test_config \
-	                        $test_script $connect_timeout $max_time $capath
+	                        $consistent_key $unmanaged $merge_config $test_config \
+	                        $test_script $connect_timeout $max_time $capath $mac_interface
 	procd_set_param respawn
 	procd_close_instance
 	logger -s "$PROG_NAME started" \