cleaned up golint issues

fritzbox_lua/README.md

@@ -7,6 +7,7 @@ There does not seem to be a complete documentation of the API, the authenticatio
 
 ## Details
 Most of the calls seem to be using the data.lua url with a http FORM POST request. As parameters the page and session id are required (e.g.: sid=<SID>&page=engery). The result is JSON with the data needed to create the respective UI.
+Some calls (like inetstat_monitor.lua) seem to use GET rather than POST, the client also supports them, but prefix GET: is needed, otherwise a post is done.
 
 Since no public documentation for the JSON format of the various pages seem to exist, you need to observe the calls made by the UI and analyse the JSON result. However the client should be generic enough to get metric and label values from all kind of nested hash and array structures contained in the JSONs.
 

fritzbox_upnp/service.go

@@ -1,4 +1,4 @@
-// Query UPNP variables from Fritz!Box devices.
+// Package fritzbox_upnp Query UPNP variables from Fritz!Box devices.
 package fritzbox_upnp
 
 // Copyright 2016 Nils Decker
@@ -16,17 +16,17 @@ package fritzbox_upnp
 // limitations under the License.
 
 import (
+	"bytes"
+	"crypto/md5"
+	"crypto/rand"
+	"crypto/tls"
 	"encoding/xml"
 	"errors"
-	"bytes"
 	"fmt"
 	"io"
 	"net/http"
-	"crypto/tls"
 	"strconv"
 	"strings"
-	"crypto/md5"
-	"crypto/rand"
 )
 
 // curl http://fritz.box:49000/igddesc.xml
@@ -36,47 +36,47 @@ import (
 // curl http://fritz.box:49000/igddslSCPD.xml
 // curl http://fritz.box:49000/igd2ipv6fwcSCPD.xml
 
-const text_xml = `text/xml; charset="utf-8"`
+const textXML = `text/xml; charset="utf-8"`
 
-var ErrInvalidSOAPResponse = errors.New("invalid SOAP response")
+var errInvalidSOAPResponse = errors.New("invalid SOAP response")
 
 // Root of the UPNP tree
 type Root struct {
-	BaseUrl  string
+	BaseURL  string
 	Username string
 	Password string
 	Device   Device              `xml:"device"`
 	Services map[string]*Service // Map of all services indexed by .ServiceType
 }
 
-// An UPNP Device
+// Device an UPNP device
 type Device struct {
 	root *Root
 
 	DeviceType       string `xml:"deviceType"`
 	FriendlyName     string `xml:"friendlyName"`
 	Manufacturer     string `xml:"manufacturer"`
-	ManufacturerUrl  string `xml:"manufacturerURL"`
+	ManufacturerURL  string `xml:"manufacturerURL"`
 	ModelDescription string `xml:"modelDescription"`
 	ModelName        string `xml:"modelName"`
 	ModelNumber      string `xml:"modelNumber"`
-	ModelUrl         string `xml:"modelURL"`
+	ModelURL         string `xml:"modelURL"`
 	UDN              string `xml:"UDN"`
 
 	Services []*Service `xml:"serviceList>service"` // Service of the device
 	Devices  []*Device  `xml:"deviceList>device"`   // Sub-Devices of the device
 
-	PresentationUrl string `xml:"presentationURL"`
+	PresentationURL string `xml:"presentationURL"`
 }
 
-// An UPNP Service
+// Service an UPNP Service
 type Service struct {
 	Device *Device
 
 	ServiceType string `xml:"serviceType"`
-	ServiceId   string `xml:"serviceId"`
-	ControlUrl  string `xml:"controlURL"`
-	EventSubUrl string `xml:"eventSubURL"`
+	ServiceID   string `xml:"serviceId"`
+	ControlURL  string `xml:"controlURL"`
+	EventSubURL string `xml:"eventSubURL"`
 	SCPDUrl     string `xml:"SCPDURL"`
 
 	Actions        map[string]*Action // All actions available on the service
@@ -88,7 +88,7 @@ type scpdRoot struct {
 	StateVariables []*StateVariable `xml:"serviceStateTable>stateVariable"`
 }
 
-// An UPNP Acton on a service
+// Action an UPNP action on a service
 type Action struct {
 	service *Service
 
@@ -97,37 +97,44 @@ type Action struct {
 	ArgumentMap map[string]*Argument // Map of arguments indexed by .Name
 }
 
-// An Inüut Argument to pass to an action
+// ActionArgument an Inüut Argument to pass to an action
 type ActionArgument struct {
 	Name  string
 	Value interface{}
 }
 
-// structs to unmarshal SOAP faults
+// SoapEnvelope struct to unmarshal SOAP faults
 type SoapEnvelope struct {
 	XMLName xml.Name `xml:"http://schemas.xmlsoap.org/soap/envelope/ Envelope"`
 	Body    SoapBody
 }
+
+// SoapBody struct
 type SoapBody struct {
 	XMLName xml.Name `xml:"http://schemas.xmlsoap.org/soap/envelope/ Body"`
 	Fault   SoapFault
 }
+
+// SoapFault struct
 type SoapFault struct {
 	XMLName     xml.Name    `xml:"http://schemas.xmlsoap.org/soap/envelope/ Fault"`
 	FaultCode   string      `xml:"faultcode"`
 	FaultString string      `xml:"faultstring"`
 	Detail      FaultDetail `xml:"detail"`
 }
+
+// FaultDetail struct
 type FaultDetail struct {
 	UpnpError UpnpError `xml:"UPnPError"`
 }
+
+// UpnpError struct
 type UpnpError struct {
 	ErrorCode        int    `xml:"errorCode"`
 	ErrorDescription string `xml:"errorDescription"`
 }
 
-
-// Returns if the action seems to be a query for information.
+// IsGetOnly Returns if the action seems to be a query for information.
 // This is determined by checking if the action has no input arguments and at least one output argument.
 func (a *Action) IsGetOnly() bool {
 	for _, a := range a.Arguments {
@@ -136,9 +143,6 @@ func (a *Action) IsGetOnly() bool {
 		}
 	}
 	return len(a.Arguments) > 0
-
-	return false
-
 }
 
 // An Argument to an action
@@ -149,14 +153,14 @@ type Argument struct {
 	StateVariable        *StateVariable
 }
 
-// A state variable that can be manipulated through actions
+// StateVariable a state variable that can be manipulated through actions
 type StateVariable struct {
 	Name         string `xml:"name"`
 	DataType     string `xml:"dataType"`
 	DefaultValue string `xml:"defaultValue"`
 }
 
-// The result of a Call() contains all output arguments of the call.
+// Result The result of a Call() contains all output arguments of the call.
 // The map is indexed by the name of the state variable.
 // The type of the value is string, uint64 or bool depending of the DataType of the variable.
 type Result map[string]interface{}
@@ -164,7 +168,7 @@ type Result map[string]interface{}
 // load the whole tree
 func (r *Root) load() error {
 	igddesc, err := http.Get(
-		fmt.Sprintf("%s/igddesc.xml", r.BaseUrl),
+		fmt.Sprintf("%s/igddesc.xml", r.BaseURL),
 	)
 
 	if err != nil {
@@ -186,7 +190,7 @@ func (r *Root) load() error {
 
 func (r *Root) loadTr64() error {
 	igddesc, err := http.Get(
-		fmt.Sprintf("%s/tr64desc.xml", r.BaseUrl),
+		fmt.Sprintf("%s/tr64desc.xml", r.BaseURL),
 	)
 
 	if err != nil {
@@ -213,7 +217,7 @@ func (d *Device) fillServices(r *Root) error {
 	for _, s := range d.Services {
 		s.Device = d
 
-		response, err := http.Get(r.BaseUrl + s.SCPDUrl)
+		response, err := http.Get(r.BaseURL + s.SCPDUrl)
 		if err != nil {
 			return err
 		}
@@ -260,24 +264,24 @@ func (d *Device) fillServices(r *Root) error {
 	return nil
 }
 
-const SoapActionXML = `<?xml version="1.0" encoding="utf-8"?>` +
+const soapActionXML = `<?xml version="1.0" encoding="utf-8"?>` +
 	`<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" s:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">` +
 	`<s:Body><u:%s xmlns:u=%s>%s</u:%s xmlns:u=%s></s:Body>` +
 	`</s:Envelope>`
 
-const SoapActionParamXML = `<%s>%s</%s>`
+const soapActionParamXML = `<%s>%s</%s>`
 
-func (a *Action) createCallHttpRequest(actionArg *ActionArgument) (*http.Request, error) {
+func (a *Action) createCallHTTPRequest(actionArg *ActionArgument) (*http.Request, error) {
 	argsString := ""
 	if actionArg != nil {
 		var buf bytes.Buffer
 		sValue := fmt.Sprintf("%v", actionArg.Value)
 		xml.EscapeText(&buf, []byte(sValue))
-		argsString += fmt.Sprintf(SoapActionParamXML, actionArg.Name, buf.String(), actionArg.Name)
+		argsString += fmt.Sprintf(soapActionParamXML, actionArg.Name, buf.String(), actionArg.Name)
 	}
-	bodystr := fmt.Sprintf(SoapActionXML, a.Name, a.service.ServiceType, argsString, a.Name, a.service.ServiceType)
+	bodystr := fmt.Sprintf(soapActionXML, a.Name, a.service.ServiceType, argsString, a.Name, a.service.ServiceType)
 
-	url := a.service.Device.root.BaseUrl + a.service.ControlUrl
+	url := a.service.Device.root.BaseURL + a.service.ControlURL
 	body := strings.NewReader(bodystr)
 
 	req, err := http.NewRequest("POST", url, body)
@@ -287,10 +291,10 @@ func (a *Action) createCallHttpRequest(actionArg *ActionArgument) (*http.Request
 
 	action := fmt.Sprintf("%s#%s", a.service.ServiceType, a.Name)
 
-	req.Header.Set("Content-Type", text_xml)
+	req.Header.Set("Content-Type", textXML)
 	req.Header.Set("SOAPAction", action)
 
-	return req, nil;	
+	return req, nil
 }
 
 // store auth header for reuse
@@ -298,7 +302,7 @@ var authHeader = ""
 
 // Call an action with argument if given
 func (a *Action) Call(actionArg *ActionArgument) (Result, error) {
-	req, err := a.createCallHttpRequest(actionArg)	
+	req, err := a.createCallHTTPRequest(actionArg)
 
 	if err != nil {
 		return nil, err
@@ -324,12 +328,12 @@ func (a *Action) Call(actionArg *ActionArgument) (Result, error) {
 			// call failed, but we have a password so calculate header and try again
 			authHeader, err = a.getDigestAuthHeader(wwwAuth, a.service.Device.root.Username, a.service.Device.root.Password)
 			if err != nil {
-				return nil, errors.New(fmt.Sprintf("%s: %s", a.Name, err.Error))
+				return nil, fmt.Errorf("%s: %s", a.Name, err.Error())
 			}
 
-			req, err = a.createCallHttpRequest(actionArg)	
+			req, err = a.createCallHTTPRequest(actionArg)
 			if err != nil {
-				return nil, errors.New(fmt.Sprintf("%s: %s", a.Name, err.Error))
+				return nil, fmt.Errorf("%s: %s", a.Name, err.Error())
 			}
 
 			req.Header.Set("Authorization", authHeader)
@@ -337,11 +341,11 @@ func (a *Action) Call(actionArg *ActionArgument) (Result, error) {
 			resp, err = http.DefaultClient.Do(req)
 
 			if err != nil {
-				return nil, errors.New(fmt.Sprintf("%s: %s", a.Name, err.Error))
+				return nil, fmt.Errorf("%s: %s", a.Name, err.Error())
 			}
 
 		} else {
-			return nil, errors.New(fmt.Sprintf("%s: Unauthorized, but no username and password given", a.Name))
+			return nil, fmt.Errorf("%s: Unauthorized, but no username and password given", a.Name)
 		}
 	}
 
@@ -363,7 +367,7 @@ func (a *Action) Call(actionArg *ActionArgument) (Result, error) {
 				soapFault := soapEnv.Body.Fault
 
 				if soapFault.FaultString == "UPnPError" {
-					upe := soapFault.Detail.UpnpError;
+					upe := soapFault.Detail.UpnpError
 
 					errMsg = fmt.Sprintf("SAOPFault: %s %d (%s)", soapFault.FaultString, upe.ErrorCode, upe.ErrorDescription)
 				} else {
@@ -371,7 +375,7 @@ func (a *Action) Call(actionArg *ActionArgument) (Result, error) {
 				}
 			}
 		}
-		return nil, errors.New(fmt.Sprintf("%s: %s", a.Name, errMsg))
+		return nil, fmt.Errorf("%s: %s", a.Name, errMsg)
 	}
 
 	return a.parseSoapResponse(resp.Body)
@@ -379,8 +383,8 @@ func (a *Action) Call(actionArg *ActionArgument) (Result, error) {
 
 func (a *Action) getDigestAuthHeader(wwwAuth string, username string, password string) (string, error) {
 	// parse www-auth header
-	if ! strings.HasPrefix(wwwAuth, "Digest ") {
-		return "", errors.New(fmt.Sprintf("WWW-Authentication header is not Digest: '%s'", wwwAuth)) 
+	if !strings.HasPrefix(wwwAuth, "Digest ") {
+		return "", fmt.Errorf("WWW-Authentication header is not Digest: '%s'", wwwAuth)
 	}
 
 	s := wwwAuth[7:]
@@ -396,35 +400,34 @@ func (a *Action) getDigestAuthHeader(wwwAuth string, username string, password s
 	if d["algorithm"] == "" {
 		d["algorithm"] = "MD5"
 	} else if d["algorithm"] != "MD5" {
-		return "", errors.New(fmt.Sprintf("digest algorithm not supported: %s != MD5", d["algorithm"]))
+		return "", fmt.Errorf("digest algorithm not supported: %s != MD5", d["algorithm"])
 	}
 
 	if d["qop"] != "auth" {
-		return "", errors.New(fmt.Sprintf("digest qop not supported: %s != auth", d["qop"]))
+		return "", fmt.Errorf("digest qop not supported: %s != auth", d["qop"])
 	}
 
 	// calc h1 and h2
-    ha1 := fmt.Sprintf("%x", md5.Sum([]byte(username + ":" + d["realm"] + ":" + password)))
+	ha1 := fmt.Sprintf("%x", md5.Sum([]byte(username+":"+d["realm"]+":"+password)))
 
-    ha2 := fmt.Sprintf("%x", md5.Sum([]byte("POST:" + a.service.ControlUrl)))
+	ha2 := fmt.Sprintf("%x", md5.Sum([]byte("POST:"+a.service.ControlURL)))
 
 	cn := make([]byte, 8)
 	rand.Read(cn)
 	cnonce := fmt.Sprintf("%x", cn)
 
 	nCounter := 1
-    nc:=fmt.Sprintf("%08x", nCounter)
+	nc := fmt.Sprintf("%08x", nCounter)
 
 	ds := strings.Join([]string{ha1, d["nonce"], nc, cnonce, d["qop"], ha2}, ":")
 	response := fmt.Sprintf("%x", md5.Sum([]byte(ds)))
 
 	authHeader := fmt.Sprintf("Digest username=\"%s\", realm=\"%s\", nonce=\"%s\", uri=\"%s\", cnonce=\"%s\", nc=%s, qop=%s, response=\"%s\", algorithm=%s",
-								username, d["realm"], d["nonce"], a.service.ControlUrl, cnonce, nc, d["qop"], response, d["algorithm"])
+		username, d["realm"], d["nonce"], a.service.ControlURL, cnonce, nc, d["qop"], response, d["algorithm"])
 
 	return authHeader, nil
 }
 
-
 func (a *Action) parseSoapResponse(r io.Reader) (Result, error) {
 	res := make(Result)
 	dec := xml.NewDecoder(r)
@@ -455,7 +458,7 @@ func (a *Action) parseSoapResponse(r io.Reader) (Result, error) {
 				case xml.CharData:
 					val = string(element)
 				default:
-					return nil, ErrInvalidSOAPResponse
+					return nil, errInvalidSOAPResponse
 				}
 
 				converted, err := convertResult(val, arg)
@@ -497,7 +500,7 @@ func convertResult(val string, arg *Argument) (interface{}, error) {
 	}
 }
 
-// Load the services tree from an device.
+// LoadServices load the services tree from an device.
 func LoadServices(baseurl string, username string, password string) (*Root, error) {
 
 	if strings.HasPrefix(baseurl, "https://") {
@@ -506,7 +509,7 @@ func LoadServices(baseurl string, username string, password string) (*Root, erro
 	}
 
 	var root = &Root{
-		BaseUrl:  baseurl,
+		BaseURL:  baseurl,
 		Username: username,
 		Password: password,
 	}
@@ -517,7 +520,7 @@ func LoadServices(baseurl string, username string, password string) (*Root, erro
 	}
 
 	var rootTr64 = &Root{
-		BaseUrl:  baseurl,
+		BaseURL:  baseurl,
 		Username: username,
 		Password: password,
 	}

main.go

@@ -43,31 +43,31 @@ const serviceLoadRetryTime = 1 * time.Minute
 const minCacheTTL = 30
 
 var (
-	flag_test    = flag.Bool("test", false, "print all available metrics to stdout")
-	flag_luatest = flag.Bool("testLua", false, "read luaTest.json file make all contained calls and dump results")
-	flag_collect = flag.Bool("collect", false, "print configured metrics to stdout and exit")
-	flag_jsonout = flag.String("json-out", "", "store metrics also to JSON file when running test")
-
-	flag_addr             = flag.String("listen-address", "127.0.0.1:9042", "The address to listen on for HTTP requests.")
-	flag_metrics_file     = flag.String("metrics-file", "metrics.json", "The JSON file with the metric definitions.")
-	flag_disable_lua      = flag.Bool("nolua", false, "disable collecting lua metrics")
-	flag_lua_metrics_file = flag.String("lua-metrics-file", "metrics-lua.json", "The JSON file with the lua metric definitions.")
-
-	flag_gateway_url      = flag.String("gateway-url", "http://fritz.box:49000", "The URL of the FRITZ!Box")
-	flag_gateway_luaurl   = flag.String("gateway-luaurl", "http://fritz.box", "The URL of the FRITZ!Box UI")
-	flag_gateway_username = flag.String("username", "", "The user for the FRITZ!Box UPnP service")
-	flag_gateway_password = flag.String("password", "", "The password for the FRITZ!Box UPnP service")
+	flagTest    = flag.Bool("test", false, "print all available metrics to stdout")
+	flagLuaTest = flag.Bool("testLua", false, "read luaTest.json file make all contained calls and dump results")
+	flagCollect = flag.Bool("collect", false, "print configured metrics to stdout and exit")
+	flagJSONOut = flag.String("json-out", "", "store metrics also to JSON file when running test")
+
+	flagAddr           = flag.String("listen-address", "127.0.0.1:9042", "The address to listen on for HTTP requests.")
+	flagMetricsFile    = flag.String("metrics-file", "metrics.json", "The JSON file with the metric definitions.")
+	flagDisableLua     = flag.Bool("nolua", false, "disable collecting lua metrics")
+	flagLuaMetricsFile = flag.String("lua-metrics-file", "metrics-lua.json", "The JSON file with the lua metric definitions.")
+
+	flagGatewayURL    = flag.String("gateway-url", "http://fritz.box:49000", "The URL of the FRITZ!Box")
+	flagGatewayLuaURL = flag.String("gateway-luaurl", "http://fritz.box", "The URL of the FRITZ!Box UI")
+	flagUsername      = flag.String("username", "", "The user for the FRITZ!Box UPnP service")
+	flagPassword      = flag.String("password", "", "The password for the FRITZ!Box UPnP service")
 )
 
 var (
-	collect_errors = prometheus.NewCounter(prometheus.CounterOpts{
-		Name: "fritzbox_exporter_collect_errors",
+	collectErrors = prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "fritzbox_exporter_collectErrors",
 		Help: "Number of collection errors.",
 	})
 )
 var (
-	lua_collect_errors = prometheus.NewCounter(prometheus.CounterOpts{
-		Name: "fritzbox_exporter_lua_collect_errors",
+	luaCollectErrors = prometheus.NewCounter(prometheus.CounterOpts{
+		Name: "fritzbox_exporter_luaCollectErrors",
 		Help: "Number of lua collection errors.",
 	})
 )
@@ -92,13 +92,15 @@ var collectUpnpResultsLoaded = prometheus.NewCounter(prometheus.CounterOpts{
 	ConstLabels: prometheus.Labels{"Cache": "UPNP"},
 })
 
-type JSON_PromDesc struct {
+// JSONPromDesc metric description loaded from JSON
+type JSONPromDesc struct {
 	FqName      string            `json:"fqName"`
 	Help        string            `json:"help"`
 	VarLabels   []string          `json:"varLabels"`
 	FixedLabels map[string]string `json:"fixedLabels"`
 }
 
+// ActionArg argument for upnp action
 type ActionArg struct {
 	Name           string `json:"Name"`
 	IsIndex        bool   `json:"IsIndex"`
@@ -106,6 +108,7 @@ type ActionArg struct {
 	Value          string `json:"Value"`
 }
 
+// Metric upnp metric
 type Metric struct {
 	// initialized loading JSON
 	Service        string       `json:"service"`
@@ -113,7 +116,7 @@ type Metric struct {
 	ActionArgument *ActionArg   `json:"actionArgument"`
 	Result         string       `json:"result"`
 	OkValue        string       `json:"okValue"`
-	PromDesc       JSON_PromDesc `json:"promDesc"`
+	PromDesc       JSONPromDesc `json:"promDesc"`
 	PromType       string       `json:"promType"`
 	CacheEntryTTL  int64        `json:"cacheEntryTTL"`
 
@@ -122,16 +125,19 @@ type Metric struct {
 	MetricType prometheus.ValueType
 }
 
+// LuaTest JSON struct for API tests
 type LuaTest struct {
 	Path   string `json:"path"`
 	Params string `json:"params"`
 }
 
+// LuaLabelRename struct
 type LuaLabelRename struct {
 	MatchRegex  string `json:"matchRegex"`
 	RenameLabel string `json:"renameLabel"`
 }
 
+// LuaMetric struct
 type LuaMetric struct {
 	// initialized loading JSON
 	Path          string       `json:"path"`
@@ -139,7 +145,7 @@ type LuaMetric struct {
 	ResultPath    string       `json:"resultPath"`
 	ResultKey     string       `json:"resultKey"`
 	OkValue       string       `json:"okValue"`
-	PromDesc      JSON_PromDesc `json:"promDesc"`
+	PromDesc      JSONPromDesc `json:"promDesc"`
 	PromType      string       `json:"promType"`
 	CacheEntryTTL int64        `json:"cacheEntryTTL"`
 
@@ -150,28 +156,30 @@ type LuaMetric struct {
 	LuaMetricDef lua.LuaMetricValueDefinition
 }
 
+// LuaMetricsFile json struct
 type LuaMetricsFile struct {
 	LabelRenames []LuaLabelRename `json:"labelRenames"`
 	Metrics      []*LuaMetric     `json:"metrics"`
 }
 
-type UpnpCacheEntry struct {
+type upnpCacheEntry struct {
 	Timestamp int64
 	Result    *upnp.Result
 }
 
-type LuaCacheEntry struct {
+type luaCacheEntry struct {
 	Timestamp int64
 	Result    *map[string]interface{}
 }
 
 var metrics []*Metric
 var luaMetrics []*LuaMetric
-var upnpCache map[string]*UpnpCacheEntry
-var luaCache map[string]*LuaCacheEntry
+var upnpCache map[string]*upnpCacheEntry
+var luaCache map[string]*luaCacheEntry
 
+// FritzboxCollector main struct
 type FritzboxCollector struct {
-	Url      string
+	URL      string
 	Gateway  string
 	Username string
 	Password string
@@ -185,32 +193,32 @@ type FritzboxCollector struct {
 }
 
 // simple ResponseWriter to collect output
-type TestResponseWriter struct {
+type testResponseWriter struct {
 	header     http.Header
 	statusCode int
 	body       bytes.Buffer
 }
 
-func (w *TestResponseWriter) Header() http.Header {
+func (w *testResponseWriter) Header() http.Header {
 	return w.header
 }
 
-func (w *TestResponseWriter) Write(b []byte) (int, error) {
+func (w *testResponseWriter) Write(b []byte) (int, error) {
 	return w.body.Write(b)
 }
 
-func (w *TestResponseWriter) WriteHeader(statusCode int) {
+func (w *testResponseWriter) WriteHeader(statusCode int) {
 	w.statusCode = statusCode
 }
 
-func (w *TestResponseWriter) String() string {
+func (w *testResponseWriter) String() string {
 	return w.body.String()
 }
 
 // LoadServices tries to load the service information. Retries until success.
 func (fc *FritzboxCollector) LoadServices() {
 	for {
-		root, err := upnp.LoadServices(fc.Url, fc.Username, fc.Password)
+		root, err := upnp.LoadServices(fc.URL, fc.Username, fc.Password)
 		if err != nil {
 			fmt.Printf("cannot load services: %s\n", err)
 
@@ -227,18 +235,19 @@ func (fc *FritzboxCollector) LoadServices() {
 	}
 }
 
+// Describe describe metric
 func (fc *FritzboxCollector) Describe(ch chan<- *prometheus.Desc) {
 	for _, m := range metrics {
 		ch <- m.Desc
 	}
 }
 
-func (fc *FritzboxCollector) ReportMetric(ch chan<- prometheus.Metric, m *Metric, result upnp.Result) {
+func (fc *FritzboxCollector) reportMetric(ch chan<- prometheus.Metric, m *Metric, result upnp.Result) {
 
 	val, ok := result[m.Result]
 	if !ok {
 		fmt.Printf("%s.%s has no result %s", m.Service, m.Action, m.Result)
-		collect_errors.Inc()
+		collectErrors.Inc()
 		return
 	}
 
@@ -260,7 +269,7 @@ func (fc *FritzboxCollector) ReportMetric(ch chan<- prometheus.Metric, m *Metric
 		}
 	default:
 		fmt.Println("unknown type", val)
-		collect_errors.Inc()
+		collectErrors.Inc()
 		return
 	}
 
@@ -291,7 +300,7 @@ func (fc *FritzboxCollector) ReportMetric(ch chan<- prometheus.Metric, m *Metric
 		labels...)
 }
 
-func (fc *FritzboxCollector) GetActionResult(metric *Metric, actionName string, actionArg *upnp.ActionArgument) (upnp.Result, error) {
+func (fc *FritzboxCollector) getActionResult(metric *Metric, actionName string, actionArg *upnp.ActionArgument) (upnp.Result, error) {
 
 	key := metric.Service + "|" + actionName
 
@@ -304,7 +313,7 @@ func (fc *FritzboxCollector) GetActionResult(metric *Metric, actionName string,
 
 	cacheEntry := upnpCache[key]
 	if cacheEntry == nil {
-		cacheEntry = &UpnpCacheEntry{}
+		cacheEntry = &upnpCacheEntry{}
 		upnpCache[key] = cacheEntry
 	} else if now-cacheEntry.Timestamp > metric.CacheEntryTTL {
 		cacheEntry.Result = nil
@@ -337,6 +346,7 @@ func (fc *FritzboxCollector) GetActionResult(metric *Metric, actionName string,
 	return *cacheEntry.Result, nil
 }
 
+// Collect collect upnp metrics
 func (fc *FritzboxCollector) Collect(ch chan<- prometheus.Metric) {
 	fc.Lock()
 	root := fc.Root
@@ -355,11 +365,11 @@ func (fc *FritzboxCollector) Collect(ch chan<- prometheus.Metric) {
 			value = aa.Value
 
 			if aa.ProviderAction != "" {
-				provRes, err := fc.GetActionResult(m, aa.ProviderAction, nil)
+				provRes, err := fc.getActionResult(m, aa.ProviderAction, nil)
 
 				if err != nil {
 					fmt.Printf("Error getting provider action %s result for %s.%s: %s\n", aa.ProviderAction, m.Service, m.Action, err.Error())
-					collect_errors.Inc()
+					collectErrors.Inc()
 					continue
 				}
 
@@ -367,7 +377,7 @@ func (fc *FritzboxCollector) Collect(ch chan<- prometheus.Metric) {
 				value, ok = provRes[aa.Value] // Value contains the result name for provider actions
 				if !ok {
 					fmt.Printf("provider action %s for %s.%s has no result", m.Service, m.Action, aa.Value)
-					collect_errors.Inc()
+					collectErrors.Inc()
 					continue
 				}
 			}
@@ -377,21 +387,21 @@ func (fc *FritzboxCollector) Collect(ch chan<- prometheus.Metric) {
 				count, err := strconv.Atoi(sval)
 				if err != nil {
 					fmt.Println(err.Error())
-					collect_errors.Inc()
+					collectErrors.Inc()
 					continue
 				}
 
 				for i := 0; i < count; i++ {
 					actArg = &upnp.ActionArgument{Name: aa.Name, Value: i}
-					result, err := fc.GetActionResult(m, m.Action, actArg)
+					result, err := fc.getActionResult(m, m.Action, actArg)
 
 					if err != nil {
 						fmt.Println(err.Error())
-						collect_errors.Inc()
+						collectErrors.Inc()
 						continue
 					}
 
-					fc.ReportMetric(ch, m, result)
+					fc.reportMetric(ch, m, result)
 				}
 
 				continue
@@ -400,15 +410,15 @@ func (fc *FritzboxCollector) Collect(ch chan<- prometheus.Metric) {
 			}
 		}
 
-		result, err := fc.GetActionResult(m, m.Action, actArg)
+		result, err := fc.getActionResult(m, m.Action, actArg)
 
 		if err != nil {
 			fmt.Println(err.Error())
-			collect_errors.Inc()
+			collectErrors.Inc()
 			continue
 		}
 
-		fc.ReportMetric(ch, m, result)
+		fc.reportMetric(ch, m, result)
 	}
 
 	// if lua is enabled now also collect metrics
@@ -426,7 +436,7 @@ func (fc *FritzboxCollector) collectLua(ch chan<- prometheus.Metric) {
 
 		cacheEntry := luaCache[key]
 		if cacheEntry == nil {
-			cacheEntry = &LuaCacheEntry{}
+			cacheEntry = &luaCacheEntry{}
 			luaCache[key] = cacheEntry
 		} else if now-cacheEntry.Timestamp > lm.CacheEntryTTL {
 			cacheEntry.Result = nil
@@ -437,7 +447,7 @@ func (fc *FritzboxCollector) collectLua(ch chan<- prometheus.Metric) {
 
 			if err != nil {
 				fmt.Printf("Error loading %s for %s.%s: %s\n", lm.Path, lm.ResultPath, lm.ResultKey, err.Error())
-				lua_collect_errors.Inc()
+				luaCollectErrors.Inc()
 				continue
 			}
 
@@ -445,7 +455,7 @@ func (fc *FritzboxCollector) collectLua(ch chan<- prometheus.Metric) {
 			data, err = lua.ParseJSON(pageData)
 			if err != nil {
 				fmt.Printf("Error parsing JSON from %s for %s.%s: %s\n", lm.Path, lm.ResultPath, lm.ResultKey, err.Error())
-				lua_collect_errors.Inc()
+				luaCollectErrors.Inc()
 				continue
 			}
 
@@ -460,7 +470,7 @@ func (fc *FritzboxCollector) collectLua(ch chan<- prometheus.Metric) {
 
 		if err != nil {
 			fmt.Printf("Error getting metric values for %s.%s: %s\n", lm.ResultPath, lm.ResultKey, err.Error())
-			lua_collect_errors.Inc()
+			luaCollectErrors.Inc()
 			continue
 		}
 
@@ -500,7 +510,7 @@ func (fc *FritzboxCollector) reportLuaMetric(ch chan<- prometheus.Metric, lm *Lu
 }
 
 func test() {
-	root, err := upnp.LoadServices(*flag_gateway_url, *flag_gateway_username, *flag_gateway_password)
+	root, err := upnp.LoadServices(*flagGatewayURL, *flagUsername, *flagPassword)
 	if err != nil {
 		panic(err)
 	}
@@ -516,7 +526,7 @@ func test() {
 	sort.Strings(serviceKeys)
 	for _, k := range serviceKeys {
 		s := root.Services[k]
-		fmt.Printf("Service: %s (Url: %s)\n", k, s.ControlUrl)
+		fmt.Printf("Service: %s (Url: %s)\n", k, s.ControlURL)
 
 		actionKeys := []string{}
 		for l := range s.Actions {
@@ -571,10 +581,10 @@ func test() {
 
 	json.WriteString("\n]")
 
-	if *flag_jsonout != "" {
-		err := ioutil.WriteFile(*flag_jsonout, json.Bytes(), 0644)
+	if *flagJSONOut != "" {
+		err := ioutil.WriteFile(*flagJSONOut, json.Bytes(), 0644)
 		if err != nil {
-			fmt.Printf("Failed writing JSON file '%s': %s\n", *flag_jsonout, err.Error())
+			fmt.Printf("Failed writing JSON file '%s': %s\n", *flagJSONOut, err.Error())
 		}
 	}
 }
@@ -595,7 +605,7 @@ func testLua() {
 	}
 
 	// create session struct and init params
-	luaSession := lua.LuaSession{BaseURL: *flag_gateway_luaurl, Username: *flag_gateway_username, Password: *flag_gateway_password}
+	luaSession := lua.LuaSession{BaseURL: *flagGatewayLuaURL, Username: *flagUsername, Password: *flagPassword}
 
 	for _, test := range luaTests {
 		fmt.Printf("TESTING: %s (%s)\n", test.Path, test.Params)
@@ -609,7 +619,8 @@ func testLua() {
 			fmt.Println(string(pageData))
 		}
 
-		fmt.Println("\n")
+		fmt.Println()
+		fmt.Println()
 	}
 }
 
@@ -629,24 +640,24 @@ func getValueType(vt string) prometheus.ValueType {
 func main() {
 	flag.Parse()
 
-	u, err := url.Parse(*flag_gateway_url)
+	u, err := url.Parse(*flagGatewayURL)
 	if err != nil {
 		fmt.Println("invalid URL:", err)
 		return
 	}
 
-	if *flag_test {
+	if *flagTest {
 		test()
 		return
 	}
 
-	if *flag_luatest {
+	if *flagLuaTest {
 		testLua()
 		return
 	}
 
 	// read metrics
-	jsonData, err := ioutil.ReadFile(*flag_metrics_file)
+	jsonData, err := ioutil.ReadFile(*flagMetricsFile)
 	if err != nil {
 		fmt.Println("error reading metric file:", err)
 		return
@@ -659,12 +670,12 @@ func main() {
 	}
 
 	// create a map for caching results
-	upnpCache = make(map[string]*UpnpCacheEntry)
+	upnpCache = make(map[string]*upnpCacheEntry)
 
 	var luaSession *lua.LuaSession
 	var luaLabelRenames *[]lua.LabelRename
-	if !*flag_disable_lua {
-		jsonData, err := ioutil.ReadFile(*flag_lua_metrics_file)
+	if !*flagDisableLua {
+		jsonData, err := ioutil.ReadFile(*flagLuaMetricsFile)
 		if err != nil {
 			fmt.Println("error reading lua metric file:", err)
 			return
@@ -678,7 +689,7 @@ func main() {
 		}
 
 		// create a map for caching results
-		luaCache = make(map[string]*LuaCacheEntry)
+		luaCache = make(map[string]*luaCacheEntry)
 
 		// init label renames
 		lblRen := make([]lua.LabelRename, 0)
@@ -727,9 +738,9 @@ func main() {
 		}
 
 		luaSession = &lua.LuaSession{
-			BaseURL:  *flag_gateway_luaurl,
-			Username: *flag_gateway_username,
-			Password: *flag_gateway_password,
+			BaseURL:  *flagGatewayLuaURL,
+			Username: *flagUsername,
+			Password: *flagPassword,
 		}
 	}
 
@@ -753,28 +764,28 @@ func main() {
 	}
 
 	collector := &FritzboxCollector{
-		Url:      *flag_gateway_url,
+		URL:      *flagGatewayURL,
 		Gateway:  u.Hostname(),
-		Username: *flag_gateway_username,
-		Password: *flag_gateway_password,
+		Username: *flagUsername,
+		Password: *flagPassword,
 
 		LuaSession:   luaSession,
 		LabelRenames: luaLabelRenames,
 	}
 
-	if *flag_collect {
+	if *flagCollect {
 		collector.LoadServices()
 
 		prometheus.MustRegister(collector)
-		prometheus.MustRegister(collect_errors)
+		prometheus.MustRegister(collectErrors)
 		if luaSession != nil {
-			prometheus.MustRegister(lua_collect_errors)
+			prometheus.MustRegister(luaCollectErrors)
 		}
 
 		fmt.Println("collecting metrics via http")
 
 		// simulate HTTP request without starting actual http server
-		writer := TestResponseWriter{header: http.Header{}}
+		writer := testResponseWriter{header: http.Header{}}
 		request := http.Request{}
 		promhttp.Handler().ServeHTTP(&writer, &request)
 
@@ -786,18 +797,18 @@ func main() {
 	go collector.LoadServices()
 
 	prometheus.MustRegister(collector)
-	prometheus.MustRegister(collect_errors)
+	prometheus.MustRegister(collectErrors)
 	prometheus.MustRegister(collectUpnpResultsCached)
 	prometheus.MustRegister(collectUpnpResultsLoaded)
 
 	if luaSession != nil {
-		prometheus.MustRegister(lua_collect_errors)
+		prometheus.MustRegister(luaCollectErrors)
 		prometheus.MustRegister(collectLuaResultsCached)
 		prometheus.MustRegister(collectLuaResultsLoaded)
 	}
 
 	http.Handle("/metrics", promhttp.Handler())
-	fmt.Printf("metrics available at http://%s/metrics\n", *flag_addr)
+	fmt.Printf("metrics available at http://%s/metrics\n", *flagAddr)
 
-	log.Fatal(http.ListenAndServe(*flag_addr, nil))
+	log.Fatal(http.ListenAndServe(*flagAddr, nil))
 }