openconnect: allow specifying "os"

Some servers might be implementing ACLs based on the value specified by
openconnect for "os", allow that to be configured.

Signed-off-by: Florian Fainelli <florian@openwrt.org>

net/openconnect/files/openconnect.sh

@@ -13,6 +13,7 @@ proto_openconnect_init_config() {
 	proto_config_add_string "token_mode"
 	proto_config_add_string "token_secret"
 	proto_config_add_string "interface"
+	proto_config_add_string "os"
 	no_device=1
 	available=1
 }
@@ -20,7 +21,7 @@ proto_openconnect_init_config() {
 proto_openconnect_setup() {
 	local config="$1"
 
-	json_get_vars server port username serverhash authgroup password interface token_mode token_secret
+	json_get_vars server port username serverhash authgroup password interface token_mode token_secret os
 
 	grep -q tun /proc/modules || insmod tun
 
@@ -68,6 +69,7 @@ proto_openconnect_setup() {
 
 	[ -n "$token_mode" ] && append cmdline "--token-mode=$token_mode"
 	[ -n "$token_secret" ] && append cmdline "--token-secret=$token_secret"
+	[ -n "$os" ] && append cmdline "--os=$os"
 
 	proto_export INTERFACE="$config"
 	logger -t openconnect "executing 'openconnect $cmdline'"