Combine user args with generated args

Generated arguments will be added only if matching arguments were not
specified by the user. User arguments will be placed after generated
arguments. This allows the user to override any generated configuration
values.

bin/ovpn_run

@@ -13,7 +13,29 @@ set -e
 cd $OPENVPN
 
 # Build runtime arguments array based on environment
-ARGS=("--config" "$OPENVPN/openvpn.conf")
+USER_ARGS=("${@}")
+ARGS=()
+
+# Checks if ARGS already contains the given value
+function hasArg {
+    local element
+    for element in "${@:2}"; do
+        [ "${element}" == "${1}" ] && return 0
+    done
+    return 1
+}
+
+# Adds the given argument if it's not already specified.
+function addArg {
+    local arg="${1}"
+    [ $# -ge 1 ] && local val="${2}"
+    if ! hasArg "${arg}" "${USER_ARGS[@]}"; then
+        ARGS+=("${arg}")
+        [ $# -ge 1 ] && ARGS+=("${val}")
+    fi
+}
+
+addArg "--config" "$OPENVPN/openvpn.conf"
 
 source "$OPENVPN/ovpn_env.sh"
 
@@ -23,7 +45,7 @@ if [ ! -c /dev/net/tun ]; then
 fi
 
 if [ -d "$OPENVPN/ccd" ]; then
-    ARGS+=("--client-config-dir" "$OPENVPN/ccd")
+    addArg "--client-config-dir" "$OPENVPN/ccd"
 fi
 
 # When using --net=host, use this to specify nat device.
@@ -48,7 +70,7 @@ if [ -r "$EASYRSA_PKI/crl.pem" ]; then
         ln "$EASYRSA_PKI/crl.pem" "$OPENVPN/crl.pem"
         chmod 644 "$OPENVPN/crl.pem"
     fi
-    ARGS+=("--crl-verify" "$OPENVPN/crl.pem")
+    addArg "--crl-verify" "$OPENVPN/crl.pem"
 fi
 
 ip -6 route show default 2>/dev/null
@@ -61,8 +83,6 @@ if [ $? = 0 ]; then
     sysctl -w net.ipv6.conf.all.forwarding=1 || echo "Failed to enable IPv6 Forwarding"
 fi
 
-if [ "$#" -gt 0 ]; then
-    exec openvpn "$@"
-else
-    exec openvpn ${ARGS[@]}
-fi
+echo "Running 'openvpn ${ARGS[@]} ${USER_ARGS[@]}'"
+exec openvpn ${ARGS[@]} ${USER_ARGS[@]}
+