comgt: ncm: select first available network interface for device

Some modems expose multiple network interfaces on the same USB device,
causing the connection setup script to fail, because glob matching in
the detection phase causes 'ls' to output more than one interface name
plus their base directories in sysfs. Avoid that by listing the
directories explicitly and then selecting first available interface.
This is the case for some variants of ZTE MF286R built-in modem, which
exposes both RNDIS and CDC-ECM network interfaces, causing the
connection setup to fail.

Signed-off-by: Lech Perczak <[email protected]>

package/network/utils/comgt/files/ncm.sh

@@ -26,7 +26,7 @@ proto_ncm_init_config() {
 proto_ncm_setup() {
 	local interface="$1"
 
-	local manufacturer initialize setmode connect finalize devname devpath
+	local manufacturer initialize setmode connect finalize devname devpath ifpath
 
 	local device ifname  apn auth username password pincode delay mode pdptype profile $PROTO_DEFAULT_OPTIONS
 	json_get_vars device ifname apn auth username password pincode delay mode pdptype profile $PROTO_DEFAULT_OPTIONS
@@ -59,13 +59,14 @@ proto_ncm_setup() {
 		case "$devname" in
 		'tty'*)
 			devpath="$(readlink -f /sys/class/tty/$devname/device)"
-			ifname="$( ls "$devpath"/../../*/net )"
+			ifpath="$devpath/../../*/net"
 			;;
 		*)
 			devpath="$(readlink -f /sys/class/usbmisc/$devname/device/)"
-			ifname="$( ls "$devpath"/net )"
+			ifpath="$devpath/net"
 			;;
 		esac
+		ifname="$(ls $(ls -1 -d $ifpath | head -n 1))"
 	}
 
 	[ -n "$ifname" ] || {