luci-app-ddns: improve performance

Every request directed to the ddns app call ddns tools module.
Ddns tools module have lots of global variable that call slow os.execute function. This adds 10 second to every ddns request even if the function that is requested doesn't need that global variable. This commit introduce env_info function that execute os.execute command by executing what is actually requested and not process all the variables. Also remove 2 unecessary module that are not used. More researh find that major slowdown was caused by the calling of ddns script for the version check. Now we check if opkg is present and use it to check ddns-scripts version.

Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>

6 files changed, 230 insertions, 96 deletions

diff --git a/applications/luci-app-ddns/Makefile b/applications/luci-app-ddns/Makefile
index bd6ddeb1b3..886b266b04 100644
--- a/applications/luci-app-ddns/Makefile
+++ b/applications/luci-app-ddns/Makefile
@@ -16,7 +16,7 @@ PKG_VERSION:=2.4.9
 
 # Release == build
 # increase on changes of translation files
-PKG_RELEASE:=3
+PKG_RELEASE:=4
 
 PKG_LICENSE:=Apache-2.0
 PKG_MAINTAINER:=Christian Schoenebeck <christian.schoenebeck@gmail.com>
diff --git a/applications/luci-app-ddns/luasrc/controller/ddns.lua b/applications/luci-app-ddns/luasrc/controller/ddns.lua
index 5f4a5118c3..bfd7a2a414 100755
--- a/applications/luci-app-ddns/luasrc/controller/ddns.lua
+++ b/applications/luci-app-ddns/luasrc/controller/ddns.lua
@@ -21,7 +21,6 @@ luci_helper = "/usr/lib/ddns/dynamic_dns_lucihelper.sh"
 
 local srv_name    = "ddns-scripts"
 local srv_ver_min = "2.7.7"			-- minimum version of service required
-local srv_ver_cmd = luci_helper .. [[ -V | awk {'print $2'}]]
 local app_name    = "luci-app-ddns"
 local app_title   = "Dynamic DNS"
 local app_version = "2.4.9-1"
@@ -29,7 +28,6 @@ local app_version = "2.4.9-1"
 function index()
 	local nxfs	= require "nixio.fs"		-- global definitions not available
 	local sys	= require "luci.sys"		-- in function index()
-	local ddns	= require "luci.tools.ddns"	-- ddns multiused functions
 	local muci	= require "luci.model.uci"
 
 	-- no config create an empty one
@@ -81,26 +79,41 @@ end
 
 -- Standardized application/service functions
 function app_title_main()
-	return	[[<a href="javascript:alert(']]
-			.. I18N.translate("Version Information")
-			.. [[\n\n]] .. app_name
-			.. [[\n\t]] .. I18N.translate("Version") .. [[:\t]] .. app_version
-			.. [[\n\n]] .. srv_name .. [[ ]] .. I18N.translate("required") .. [[:]]
-			.. [[\n\t]] .. I18N.translate("Version") .. [[:\t]]
-				.. srv_ver_min .. [[ ]] .. I18N.translate("or higher")
-			.. [[\n\n]] .. srv_name .. [[ ]] .. I18N.translate("installed") .. [[:]]
-			.. [[\n\t]] .. I18N.translate("Version") .. [[:\t]]
-				.. (service_version() or I18N.translate("NOT installed"))
-			.. [[\n\n]]
-	 	.. [[')">]]
-		.. I18N.translate(app_title)
-		.. [[</a>]]
+	tmp = {}
+	tmp[#tmp+1] = 	[[<a href="javascript:alert(']]
+	tmp[#tmp+1] = 		 I18N.translate("Version Information")
+	tmp[#tmp+1] = 		 [[\n\n]] .. app_name
+	tmp[#tmp+1] = 		 [[\n\t]] .. I18N.translate("Version") .. [[:\t]] .. app_version
+	tmp[#tmp+1] = 		 [[\n\n]] .. srv_name .. [[ ]] .. I18N.translate("required") .. [[:]]
+	tmp[#tmp+1] = 		 [[\n\t]] .. I18N.translate("Version") .. [[:\t]]
+	tmp[#tmp+1] = 			 srv_ver_min .. [[ ]] .. I18N.translate("or higher")
+	tmp[#tmp+1] = 		 [[\n\n]] .. srv_name .. [[ ]] .. I18N.translate("installed") .. [[:]]
+	tmp[#tmp+1] = 		 [[\n\t]] .. I18N.translate("Version") .. [[:\t]]
+	tmp[#tmp+1] = 			 (service_version() or I18N.translate("NOT installed"))
+	tmp[#tmp+1] = 		 [[\n\n]]
+	tmp[#tmp+1] = 	 [[')">]]
+	tmp[#tmp+1] = 	 I18N.translate(app_title)
+	tmp[#tmp+1] = 	 [[</a>]]
+		
+	return table.concat(tmp)
 end
 function service_version()
-	local ver = nil
 
+	local nxfs	= require "nixio.fs"
+
+	local ver = nil
+	local ver_helper
+	
+	if nxfs.access("/bin/opkg") then
+		ver_helper = "/bin/opkg info " .. srv_name .. " | grep 'Version'"
+	else
+		ver_helper = luci_helper .. " -V"
+	end
+	
+	local srv_ver_cmd = ver_helper .. " | awk {'print $2'} "
+	
 	ver = UTIL.exec(srv_ver_cmd)
-	if #ver > 0 then return ver end
+	if ver and #ver > 0 then return ver end
 
 	IPKG.list_installed(srv_name, function(n, v, d)
 			if v and (#v > 0) then ver = v end
@@ -108,6 +121,7 @@ function service_version()
 	)
 	return	ver
 end
+
 function service_ok()
 	return	IPKG.compare_versions((service_version() or "0"), ">=", srv_ver_min)
 end
diff --git a/applications/luci-app-ddns/luasrc/model/cbi/ddns/detail.lua b/applications/luci-app-ddns/luasrc/model/cbi/ddns/detail.lua
index 977dbe34b1..10d39c7183 100644
--- a/applications/luci-app-ddns/luasrc/model/cbi/ddns/detail.lua
+++ b/applications/luci-app-ddns/luasrc/model/cbi/ddns/detail.lua
@@ -292,6 +292,10 @@ function luh.parse(self, section, novld)
 end
 
 -- use_ipv6 -- ################################################################
+
+--We call it globally as it's called 11 times even outside specific function, saves 11 os.execute slow command!
+local has_ipv6 = DDNS.env_info("has_ipv6") 
+
 usev6 = ns:taboption("basic", ListValue, "use_ipv6",
 	translate("IP address version"),
 	translate("Defines which IP address 'IPv4/IPv6' is send to the DDNS provider") )
@@ -300,16 +304,16 @@ usev6.default = "0"
 usev6:value("0", translate("IPv4-Address") )
 function usev6.cfgvalue(self, section)
 	local value = AbstractValue.cfgvalue(self, section) or "0"
-	if DDNS.has_ipv6 or (value == "1" and not DDNS.has_ipv6) then
+	if has_ipv6 or (value == "1" and not has_ipv6) then
 		self:value("1", translate("IPv6-Address") )
 	end
-	if value == "1" and not DDNS.has_ipv6 then
+	if value == "1" and not has_ipv6 then
 		self.description = err_ipv6_basic
 	end
 	return value
 end
 function usev6.validate(self, value)
-	if (value == "1" and DDNS.has_ipv6) or value == "0" then
+	if (value == "1" and has_ipv6) or value == "0" then
 		return value
 	end
 	return nil, err_tab_basic(self) .. err_ipv6_plain
@@ -360,7 +364,7 @@ svc6 = ns:taboption("basic", ListValue, "ipv6_service_name",
 	translate("DDNS Service provider") .. " [IPv6]" )
 svc6.default	= "-"
 svc6:depends("use_ipv6", "1")	-- only show on IPv6
-if not DDNS.has_ipv6 then
+if not has_ipv6 then
 	svc6.description = err_ipv6_basic
 end
 function svc6.cfgvalue(self, section)
@@ -374,7 +378,7 @@ function svc6.cfgvalue(self, section)
 end
 function svc6.validate(self, value)
 	if usev6:formvalue(section) == "1" then	-- do only on IPv6
-		if DDNS.has_ipv6 then return value end
+		if has_ipv6 then return value end
 		return nil, err_tab_basic(self) .. err_ipv6_plain
 	else
 		return ""	-- suppress validate error
@@ -586,13 +590,17 @@ end
 svc6:value("-", translate("-- custom --") )
 
 -- IPv4/IPv6 - use_https -- ###################################################
-if DDNS.has_ssl or ( ( m:get(section, "use_https") or "0" ) == "1" ) then
+
+--We call it globally as it's called 4 times outside specific function.
+local has_ssl = DDNS.env_info("has_ssl")
+
+if has_ssl or ( ( m:get(section, "use_https") or "0" ) == "1" ) then
 	https = ns:taboption("basic", Flag, "use_https",
 		translate("Use HTTP Secure") )
 	https.orientation = "horizontal"
 	function https.cfgvalue(self, section)
 		local value = AbstractValue.cfgvalue(self, section)
-		if not DDNS.has_ssl and value == "1" then
+		if not has_ssl and value == "1" then
 			self.description = bold_on .. font_red ..
 				translate("HTTPS not supported") .. font_off .. "<br />" ..
 				translate("please disable") .. " !" .. bold_off
@@ -602,7 +610,7 @@ if DDNS.has_ssl or ( ( m:get(section, "use_https") or "0" ) == "1" ) then
 		return value
 	end
 	function https.validate(self, value)
-		if (value == "1" and DDNS.has_ssl ) or value == "0" then return value end
+		if (value == "1" and has_ssl ) or value == "0" then return value end
 		return nil, err_tab_basic(self) .. translate("HTTPS not supported") .. " !"
 	end
 	function https.write(self, section, value)
@@ -616,7 +624,7 @@ if DDNS.has_ssl or ( ( m:get(section, "use_https") or "0" ) == "1" ) then
 end
 
 -- IPv4/IPv6 - cacert -- ######################################################
-if DDNS.has_ssl then
+if has_ssl then
 	cert = ns:taboption("basic", Value, "cacert",
 		translate("Path to CA-Certificate"),
 		translate("directory or path/file") .. "<br />" ..
@@ -706,7 +714,7 @@ src6:value("network", translate("Network"))
 src6:value("web", translate("URL"))
 src6:value("interface", translate("Interface"))
 src6:value("script", translate("Script"))
-if not DDNS.has_ipv6 then
+if not has_ipv6 then
 	src6.description = err_ipv6_other
 end
 function src6.cfgvalue(self, section)
@@ -715,7 +723,7 @@ end
 function src6.validate(self, value)
 	if usev6:formvalue(section) ~= "1" then
 		return ""	-- ignore on IPv4 selected
-	elseif not DDNS.has_ipv6 then
+	elseif not has_ipv6 then
 		return nil, err_tab_adv(self) .. err_ipv6_plain
 	elseif not _verify_ip_source() then
 		return nil, err_tab_adv(self) ..
@@ -794,7 +802,7 @@ ipn6 = ns:taboption("advanced", ListValue, "ipv6_network",
 ipn6:depends("ipv6_source", "network")
 ipn6.default = "wan6"
 WADM.cbi_add_networks(ipn6)
-if DDNS.has_ipv6 then
+if has_ipv6 then
 	ipn6.description = translate("Defines the network to read systems IPv6-Address from")
 else
 	ipn6.description = err_ipv6_other
@@ -808,7 +816,7 @@ function ipn6.validate(self, value)
 		-- ignore if IPv4 selected OR
 		-- ignore everything except "network"
 		return ""
-	elseif DDNS.has_ipv6 then
+	elseif has_ipv6 then
 		return value
 	else
 		return nil, err_tab_adv(self) .. err_ipv6_plain
@@ -881,7 +889,7 @@ iurl6 = ns:taboption("advanced", Value, "ipv6_url",
 	translate("URL to detect") .. " [IPv6]" )
 iurl6:depends("ipv6_source", "web")
 iurl6.default = "http://checkipv6.dyndns.com"
-if DDNS.has_ipv6 then
+if has_ipv6 then
 	iurl6.description = translate("Defines the Web page to read systems IPv6-Address from")
 else
 	iurl6.description = err_ipv6_other
@@ -895,7 +903,7 @@ function iurl6.validate(self, value)
 		-- ignore if IPv4 selected OR
 		-- ignore everything except "web"
 		return ""
-	elseif not DDNS.has_ipv6 then
+	elseif not has_ipv6 then
 		return nil, err_tab_adv(self) .. err_ipv6_plain
 	elseif not value or #value == 0 then
 		return nil, err_tab_adv(self) .. translate("missing / required")
@@ -1051,7 +1059,7 @@ eif6:depends("ipv6_source", "web")
 eif6:depends("ipv6_source", "script")
 eif6.default = "wan6"
 WADM.cbi_add_networks(eif6)
-if not DDNS.has_ipv6 then
+if not has_ipv6 then
 	eif6.description = err_ipv6_other
 else
 	eif6.description = translate("Network on which the ddns-updater scripts will be started")
@@ -1065,7 +1073,7 @@ function eif6.validate(self, value)
 	 or fsrc6 == "network"
 	 or fsrc6 == "interface" then
 		return ""	-- ignore IPv4, network, interface
-	elseif not DDNS.has_ipv6 then
+	elseif not has_ipv6 then
 		return nil, err_tab_adv(self) .. err_ipv6_plain
 	else
 		return value
@@ -1084,10 +1092,13 @@ function eif6.write(self, section, value)
 end
 function eif6.parse(self, section, novld)
 	DDNS.value_parse(self, section, novld)
-end
+end 
 
 -- IPv4/IPv6 - bind_network -- ################################################
-if DDNS.has_bindnet or ( ( m:get(section, "bind_network") or "" ) ~= "" ) then
+
+local has_bindnet = DDNS.env_info("has_bindnet")
+
+if has_bindnet or ( ( m:get(section, "bind_network") or "" ) ~= "" ) then
 	bnet = ns:taboption("advanced", ListValue, "bind_network",
 		translate("Bind Network") )
 	bnet:depends("ipv4_source", "web")
@@ -1097,7 +1108,7 @@ if DDNS.has_bindnet or ( ( m:get(section, "bind_network") or "" ) ~= "" ) then
 	WADM.cbi_add_networks(bnet)
 	function bnet.cfgvalue(self, section)
 		local value = AbstractValue.cfgvalue(self, section)
-		if not DDNS.has_bindnet and value ~= "" then
+		if not has_bindnet and value ~= "" then
 			self.description = bold_on .. font_red ..
 				translate("Binding to a specific network not supported") .. font_off .. "<br />" ..
 				translate("please set to 'default'") .. " !" .. bold_off
@@ -1108,7 +1119,7 @@ if DDNS.has_bindnet or ( ( m:get(section, "bind_network") or "" ) ~= "" ) then
 		return value
 	end
 	function bnet.validate(self, value)
-		if ( (value ~= "") and DDNS.has_bindnet ) or (value == "") then return value end
+		if ( (value ~= "") and has_bindnet ) or (value == "") then return value end
 		return nil, err_tab_adv(self) .. translate("Binding to a specific network not supported") .. " !"
 	end
 	function bnet.parse(self, section, novld)
@@ -1119,13 +1130,16 @@ end
 -- IPv4 + IPv6 - force_ipversion -- ###########################################
 -- optional to force wget/curl and host to use only selected IP version
 -- command parameter "-4" or "-6"
-if DDNS.has_forceip or ( ( m:get(section, "force_ipversion") or "0" ) ~= "0" ) then
+
+local has_forceip = DDNS.env_info("has_forceip")
+
+if has_forceip or ( ( m:get(section, "force_ipversion") or "0" ) ~= "0" ) then
 	fipv = ns:taboption("advanced", Flag, "force_ipversion",
 		translate("Force IP Version") )
 	fipv.orientation = "horizontal"
 	function fipv.cfgvalue(self, section)
 		local value = AbstractValue.cfgvalue(self, section)
-		if not DDNS.has_forceip and value ~= "0" then
+		if not has_forceip and value ~= "0" then
 			self.description = bold_on .. font_red ..
 				translate("Force IP Version not supported") .. font_off .. "<br />" ..
 				translate("please disable") .. " !" .. bold_off
@@ -1135,14 +1149,17 @@ if DDNS.has_forceip or ( ( m:get(section, "force_ipversion") or "0" ) ~= "0" ) t
 		return value
 	end
 	function fipv.validate(self, value)
-		if (value == "1" and DDNS.has_forceip) or value == "0" then return value end
+		if (value == "1" and has_forceip) or value == "0" then return value end
 		return nil, err_tab_adv(self) .. translate("Force IP Version not supported")
 	end
 end
 
 -- IPv4 + IPv6 - dns_server -- ################################################
 -- optional DNS Server to use resolving my IP
-if DDNS.has_dnsserver or ( ( m:get(section, "dns_server") or "" ) ~= "" ) then
+
+local has_dnsserver = DDNS.env_info("has_dnsserver")
+
+if has_dnsserver or ( ( m:get(section, "dns_server") or "" ) ~= "" ) then
 	dns = ns:taboption("advanced", Value, "dns_server",
 		translate("DNS-Server"),
 		translate("OPTIONAL: Use non-default DNS-Server to detect 'Registered IP'.") .. "<br />" ..
@@ -1152,7 +1169,7 @@ if DDNS.has_dnsserver or ( ( m:get(section, "dns_server") or "" ) ~= "" ) then
 		-- if .datatype is set, then it is checked before calling this function
 		if not value or (#value == 0) then
 			return ""	-- ignore on empty
-		elseif not DDNS.has_dnsserver then
+		elseif not has_dnsserver then
 			return nil, err_tab_adv(self) .. translate("Specifying a DNS-Server is not supported")
 		elseif not DTYP.host(value) then
 			return nil, err_tab_adv(self) .. translate("use hostname, FQDN, IPv4- or IPv6-Address")
@@ -1179,13 +1196,16 @@ if DDNS.has_dnsserver or ( ( m:get(section, "dns_server") or "" ) ~= "" ) then
 end
 
 -- IPv4 + IPv6 - force_dnstcp -- ##############################################
-if DDNS.has_bindhost or ( ( m:get(section, "force_dnstcp") or "0" ) ~= "0" ) then
+
+local has_bindhost = DDNS.env_info("has_bindhost")
+
+if has_bindhost or ( ( m:get(section, "force_dnstcp") or "0" ) ~= "0" ) then
 	tcp = ns:taboption("advanced", Flag, "force_dnstcp",
 		translate("Force TCP on DNS") )
 	tcp.orientation = "horizontal"
 	function tcp.cfgvalue(self, section)
 		local value = AbstractValue.cfgvalue(self, section)
-		if not DDNS.has_bindhost and value ~= "0" then
+		if not has_bindhost and value ~= "0" then
 			self.description = bold_on .. font_red ..
 				translate("DNS requests via TCP not supported") .. font_off .. "<br />" ..
 				translate("please disable") .. " !" .. bold_off
@@ -1195,7 +1215,7 @@ if DDNS.has_bindhost or ( ( m:get(section, "force_dnstcp") or "0" ) ~= "0" ) the
 		return value
 	end
 	function tcp.validate(self, value)
-		if (value == "1" and DDNS.has_bindhost ) or value == "0" then
+		if (value == "1" and has_bindhost ) or value == "0" then
 			return value
 		end
 		return nil, err_tab_adv(self) .. translate("DNS requests via TCP not supported")
@@ -1204,13 +1224,16 @@ end
 
 -- IPv4 + IPv6 - proxy -- #####################################################
 -- optional Proxy to use for http/https requests  [user:password@]proxyhost[:port]
-if DDNS.has_proxy or ( ( m:get(section, "proxy") or "" ) ~= "" ) then
+
+local has_proxy = DDNS.env_info("has_proxy")
+
+if has_proxy or ( ( m:get(section, "proxy") or "" ) ~= "" ) then
 	pxy = ns:taboption("advanced", Value, "proxy",
 		translate("PROXY-Server") )
 	pxy.placeholder="user:password@myproxy.lan:8080"
 	function pxy.cfgvalue(self, section)
 		local value = AbstractValue.cfgvalue(self, section)
-		if not DDNS.has_proxy and value ~= "" then
+		if not has_proxy and value ~= "" then
 			self.description = bold_on .. font_red ..
 				translate("PROXY-Server not supported") .. font_off .. "<br />" ..
 				translate("please remove entry") .. "!" .. bold_off
@@ -1226,7 +1249,7 @@ if DDNS.has_proxy or ( ( m:get(section, "proxy") or "" ) ~= "" ) then
 		-- if .datatype is set, then it is checked before calling this function
 		if not value or (#value == 0) then
 			return ""	-- ignore on empty
-		elseif DDNS.has_proxy then
+		elseif has_proxy then
 			local ipv6  = usev6:formvalue(section) or "0"
 			local force = fipv:formvalue(section) or "0"
 			local command = CTRL.luci_helper .. [[ -]]
diff --git a/applications/luci-app-ddns/luasrc/model/cbi/ddns/hints.lua b/applications/luci-app-ddns/luasrc/model/cbi/ddns/hints.lua
index df39a3a7e5..419201548b 100644
--- a/applications/luci-app-ddns/luasrc/model/cbi/ddns/hints.lua
+++ b/applications/luci-app-ddns/luasrc/model/cbi/ddns/hints.lua
@@ -48,7 +48,7 @@ if not SYS.init.enabled("ddns") then
 end
 
 -- No IPv6 support
-if not DDNS.has_ipv6 then
+if not DDNS.env_info("has_ipv6") then
 	local v6 = s:option(DummyValue, "_no_ipv6")
 	v6.titleref = 'http://www.openwrt.org" target="_blank'
 	v6.rawhtml  = true
@@ -60,7 +60,7 @@ if not DDNS.has_ipv6 then
 end
 
 -- No HTTPS support
-if not DDNS.has_ssl then
+if not DDNS.env_info("has_ssl") then
 	local sl = s:option(DummyValue, "_no_https")
 	sl.titleref = DISP.build_url("admin", "system", "packages")
 	sl.rawhtml  = true
@@ -74,7 +74,7 @@ if not DDNS.has_ssl then
 end
 
 -- No bind_network
-if not DDNS.has_bindnet then
+if not DDNS.env_info("has_bindnet") then
 	local bn = s:option(DummyValue, "_no_bind_network")
 	bn.titleref = DISP.build_url("admin", "system", "packages")
 	bn.rawhtml  = true
@@ -90,7 +90,7 @@ if not DDNS.has_bindnet then
 end
 
 -- currently only cURL possibly without proxy support
-if not DDNS.has_proxy then
+if not DDNS.env_info("has_proxy") then
 	local px = s:option(DummyValue, "_no_proxy")
 	px.titleref = DISP.build_url("admin", "system", "packages")
 	px.rawhtml  = true
@@ -104,7 +104,7 @@ if not DDNS.has_proxy then
 end
 
 -- "Force IP Version not supported"
-if not DDNS.has_forceip then
+if not DDNS.env_info("has_forceip") then
 	local fi = s:option(DummyValue, "_no_force_ip")
 	fi.titleref = DISP.build_url("admin", "system", "packages")
 	fi.rawhtml  = true
@@ -112,11 +112,11 @@ if not DDNS.has_forceip then
 		translate("Force IP Version not supported") .. bold_off
 	local value = translate("BusyBox's nslookup and Wget do not support to specify " ..
 				"the IP version to use for communication with DDNS Provider!")
-	if not (DDNS.has_wgetssl or DDNS.has_curl or DDNS.has_fetch) then
+	if not (DDNS.env_info("has_wgetssl") or DDNS.env_info("has_curl") or DDNS.env_info("has_fetch")) then
 		value = value .. "<br />- " ..
 			translate("You should install 'wget' or 'curl' or 'uclient-fetch' package.")
 	end
-	if not DDNS.has_bindhost then
+	if not DDNS.env_info("has_bindhost") then
 		value = value .. "<br />- " ..
 			translate("You should install 'bind-host' or 'knot-host' or 'drill' package for DNS requests.")
 	end
@@ -124,7 +124,7 @@ if not DDNS.has_forceip then
 end
 
 -- "DNS requests via TCP not supported"
-if not DDNS.has_bindhost then
+if not DDNS.env_info("has_bindhost") then
 	local dt = s:option(DummyValue, "_no_dnstcp")
 	dt.titleref = DISP.build_url("admin", "system", "packages")
 	dt.rawhtml  = true
@@ -137,7 +137,7 @@ if not DDNS.has_bindhost then
 end
 
 -- nslookup compiled with musl produce problems when using
-if not DDNS.has_dnsserver then
+if not DDNS.env_info("has_dnsserver") then
 	local ds = s:option(DummyValue, "_no_dnsserver")
 	ds.titleref = DISP.build_url("admin", "system", "packages")
 	ds.rawhtml  = true
@@ -151,7 +151,7 @@ if not DDNS.has_dnsserver then
 end
 
 -- certificates installed
-if DDNS.has_ssl and not DDNS.has_cacerts then
+if DDNS.env_info("has_ssl") and not DDNS.env_info("has_cacerts") then
 	local ca = s:option(DummyValue, "_no_certs")
 	ca.titleref = DISP.build_url("admin", "system", "packages")
 	ca.rawhtml  = true
diff --git a/applications/luci-app-ddns/luasrc/model/cbi/ddns/overview.lua b/applications/luci-app-ddns/luasrc/model/cbi/ddns/overview.lua
index 114f831c17..11f73800ea 100644
--- a/applications/luci-app-ddns/luasrc/model/cbi/ddns/overview.lua
+++ b/applications/luci-app-ddns/luasrc/model/cbi/ddns/overview.lua
@@ -1,21 +1,20 @@
 -- Copyright 2014-2018 Christian Schoenebeck <christian dot schoenebeck at gmail dot com>
 -- Licensed to the public under the Apache License 2.0.
 
-local NXFS = require "nixio.fs"
 local DISP = require "luci.dispatcher"
 local HTTP = require "luci.http"
 local SYS  = require "luci.sys"
 local CTRL = require "luci.controller.ddns"	-- this application's controller
 local DDNS = require "luci.tools.ddns"		-- ddns multiused functions
 
-local show_hints = not (DDNS.has_ipv6		-- IPv6 support
-		    and DDNS.has_ssl		-- HTTPS support
-		    and DDNS.has_proxy		-- Proxy support
-		    and DDNS.has_bindhost	-- DNS TCP support
-		    and DDNS.has_forceip	-- Force IP version
-		    and DDNS.has_dnsserver	-- DNS server support
-		    and DDNS.has_bindnet	-- Bind to network/interface
-		    and DDNS.has_cacerts	-- certificates installed at /etc/ssl/certs
+local show_hints = not (DDNS.env_info("has_ipv6")		-- IPv6 support
+				   and  DDNS.env_info("has_ssl")		-- HTTPS support
+				   and  DDNS.env_info("has_proxy")		-- Proxy support
+				   and  DDNS.env_info("has_bindhost")	-- DNS TCP support
+				   and  DDNS.env_info("has_forceip")	-- Force IP version
+				   and  DDNS.env_info("has_dnsserver")	-- DNS server support
+				   and  DDNS.env_info("has_bindnet")	-- Bind to network/interface
+				   and  DDNS.env_info("has_cacerts")	-- certificates installed at /etc/ssl/certs
 		)
 local not_enabled = not SYS.init.enabled("ddns")
 local need_update = not CTRL.service_ok()
diff --git a/applications/luci-app-ddns/luasrc/tools/ddns.lua b/applications/luci-app-ddns/luasrc/tools/ddns.lua
index 690b9b30ce..57913a51fe 100755
--- a/applications/luci-app-ddns/luasrc/tools/ddns.lua
+++ b/applications/luci-app-ddns/luasrc/tools/ddns.lua
@@ -5,36 +5,134 @@ module("luci.tools.ddns", package.seeall)
 
 local NX   = require "nixio"
 local NXFS = require "nixio.fs"
-local OPKG = require "luci.model.ipkg"
 local UCI  = require "luci.model.uci"
 local SYS  = require "luci.sys"
-local UTIL = require "luci.util"
 
-local function _check_certs()
-	local _, v = NXFS.glob("/etc/ssl/certs/*.crt")
-	if ( v == 0 ) then _, v = NXFS.glob("/etc/ssl/certs/*.pem") end
-	return (v > 0)
-end
+function env_info(type)
+
+	if ( type == "has_ssl" ) or ( type == "has_proxy" ) or ( type == "has_forceip" ) 
+	    or ( type == "has_bindnet" ) or ( type == "has_fetch" ) 
+		or ( type == "has_wgetssl" ) or ( type == "has_curl" ) 
+		or ( type == "has_curlssl" ) or ( type == "has_curlpxy" ) 
+		or ( type == "has_fetchssl" ) or ( type == "has_bbwget" ) then 
+		
+		local function has_wgetssl() 
+			return (SYS.call( [[which wget-ssl >/dev/null 2>&1]] ) == 0)	-- and true or nil
+		end
+		
+		local function has_curlssl() 
+			return (SYS.call( [[$(which curl) -V 2>&1 | grep "Protocols:" | grep -qF "https"]] ) ~= 0)
+		end
+		
+		local function has_fetch()
+			return (SYS.call( [[which uclient-fetch >/dev/null 2>&1]] ) == 0)
+		end
+		
+		local function has_fetchssl()
+			return NXFS.access("/lib/libustream-ssl.so")
+		end
+		
+		local function has_curl()
+			return (SYS.call( [[which curl >/dev/null 2>&1]] ) == 0)
+		end
+		
+		local function has_curlpxy()
+			return (SYS.call( [[grep -i "all_proxy" /usr/lib/libcurl.so* >/dev/null 2>&1]] ) == 0)
+		end
+		
+		local function has_bbwget()
+			return (SYS.call( [[$(which wget) -V 2>&1 | grep -iqF "busybox"]] ) == 0)
+		end
+		
+		if type == "has_wgetssl" then
+			return has_wgetssl()
+		
+		elseif type == "has_curl" then
+			return has_curl()
+			
+		elseif type == "has_curlssl" then
+			return has_curlssl()
+			
+		elseif type == "has_curlpxy" then
+			return has_curlpxy()
+			
+		elseif type == "has_fetch" then
+			return has_fetch()
+			
+		elseif type == "has_fetchssl" then
+			return has_fetchssl()
+			
+		elseif type == "has_bbwget" then
+			return has_bbwget()
+		
+		elseif type == "has_ssl" then
+			if has_wgetssl() then return true end
+			if has_curlssl() then return true end
+			if (has_fetch() and has_fetchssl()) then return true end
+			return false
+			
+		elseif type == "has_proxy" then
+			if has_wgetssl() then return true end
+			if has_curlpxy() then return true end
+			if has_fetch() then return true end
+			if has_bbwget() then return true end
+			return false
+			
+		elseif type == "has_forceip" then
+			if has_wgetssl() then return true end
+			if has_curl() then return true end
+			if has_fetch() then return true end -- only really needed for transfer
+			return false
+			
+		elseif type == "has_bindnet" then
+			if has_curl() then return true end
+			if has_wgetssl() then return true end
+			return false
+		end
+	
+	elseif ( type == "has_dnsserver" ) or ( type == "has_bindhost" ) or ( type == "has_hostip" ) or ( type == "has_nslookup" ) then
+		local function has_bindhost() 
+			if (SYS.call( [[which host >/dev/null 2>&1]] ) == 0) then return true end
+			if (SYS.call( [[which host >/dev/null 2>&1]] ) == 0) then return true end
+			if (SYS.call( [[which khost >/dev/null 2>&1]] ) == 0) then return true end
+			if (SYS.call( [[which drill >/dev/null 2>&1]] ) == 0) then return true end
+			return false
+		end
+		
+		local function has_hostip()
+			return (SYS.call( [[which hostip >/dev/null 2>&1]] ) == 0)
+		end
+		
+		local function has_nslookup()
+			return (SYS.call( [[$(which nslookup) localhost 2>&1 | grep -qF "(null)"]] ) ~= 0)
+		end
+		
+		if type == "has_bindhost" then
+			return has_bindhost()
+		elseif type == "has_hostip" then
+			return has_hostip()
+		elseif type == "has_nslookup" then
+			return has_nslookup()
+		elseif tyep == "has_dnsserver" then
+			if has_bindhost() then return true end
+			if has_hostip() then return true end
+			if has_nslookup() then return true end
+			return false
+		end
+		
+	elseif type == "has_ipv6" then
+		return (NXFS.access("/proc/net/ipv6_route") and NXFS.access("/usr/sbin/ip6tables"))
+		
+	elseif type == "has_cacerts" then
+		--old _check_certs() local function 
+		local _, v = NXFS.glob("/etc/ssl/certs/*.crt")
+		if ( v == 0 ) then _, v = NXFS.glob("/etc/ssl/certs/*.pem") end
+		return (v > 0)
+	else
+		return
+	end
 
-has_wgetssl	= (SYS.call( [[which wget-ssl >/dev/null 2>&1]] ) == 0)	-- and true or nil
-has_curl	= (SYS.call( [[which curl >/dev/null 2>&1]] ) == 0)
-has_curlssl	= (SYS.call( [[$(which curl) -V 2>&1 | grep "Protocols:" | grep -qF "https"]] ) ~= 0)
-has_curlpxy	= (SYS.call( [[grep -i "all_proxy" /usr/lib/libcurl.so* >/dev/null 2>&1]] ) == 0)
-has_fetch	= (SYS.call( [[which uclient-fetch >/dev/null 2>&1]] ) == 0)
-has_fetchssl	= NXFS.access("/lib/libustream-ssl.so")
-has_bbwget	= (SYS.call( [[$(which wget) -V 2>&1 | grep -iqF "busybox"]] ) == 0)
-has_bindhost	= (SYS.call( [[which host >/dev/null 2>&1]] ) == 0)
-		or (SYS.call( [[which khost >/dev/null 2>&1]] ) == 0)
-		or (SYS.call( [[which drill >/dev/null 2>&1]] ) == 0)
-has_hostip	= (SYS.call( [[which hostip >/dev/null 2>&1]] ) == 0)
-has_nslookup	= (SYS.call( [[$(which nslookup) localhost 2>&1 | grep -qF "(null)"]] ) ~= 0)
-has_ipv6	= (NXFS.access("/proc/net/ipv6_route") and NXFS.access("/usr/sbin/ip6tables"))
-has_ssl		= (has_wgetssl or has_curlssl or (has_fetch and has_fetchssl))
-has_proxy	= (has_wgetssl or has_curlpxy or has_fetch or has_bbwget)
-has_forceip	= (has_wgetssl or has_curl or has_fetch) -- only really needed for transfer
-has_dnsserver	= (has_bindhost or has_hostip or has_nslookup)
-has_bindnet	= (has_wgetssl or has_curl)
-has_cacerts	= _check_certs()
+end
 
 -- function to calculate seconds from given interval and unit
 function calc_seconds(interval, unit)