openconnect: allow disable dtls with bool option no_dtls

openconnect may emit following error logs every minute when negotiating
with deployments forbidding usage of dtls

  Thu Aug 27 04:11:59 2020 daemon.notice openconnect[12024]: DTLS handshake failed: Error in the push function.
  Thu Aug 27 04:11:59 2020 daemon.notice openconnect[12024]: (Is a firewall preventing you from sending UDP packets?)

Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>

net/openconnect/Makefile

@@ -9,7 +9,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=openconnect
 PKG_VERSION:=8.10
-PKG_RELEASE:=1
+PKG_RELEASE:=2
 
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz
 PKG_SOURCE_URL:=ftp://ftp.infradead.org/pub/openconnect/

net/openconnect/files/openconnect.sh

@@ -15,6 +15,7 @@ proto_openconnect_init_config() {
 	proto_config_add_int "port"
 	proto_config_add_int "mtu"
 	proto_config_add_int "juniper"
+	proto_config_add_boolean "no_dtls"
 	proto_config_add_string "interface"
 	proto_config_add_string "username"
 	proto_config_add_string "serverhash"
@@ -46,6 +47,7 @@ proto_openconnect_setup() {
 		interface \
 		juniper \
 		mtu \
+		no_dtls \
 		os \
 		password \
 		password2 \
@@ -72,6 +74,7 @@ proto_openconnect_setup() {
 	[ -n "$port" ] && port=":$port"
 
 	append_args "$server$port" -i "$ifname" --non-inter --syslog --script /lib/netifd/vpnc-script
+	[ "$no_dtls" = 1 ] && append_args --no-dtls
 	[ -n "$mtu" ] && append_args --mtu "$mtu"
 
 	# migrate to standard config files