Pull request: all: imp code, err handling

Closes #2571.

Squashed commit of the following:

commit a5b50ee011a995f4ab3d93314acd6f0ca82d99cf
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Mon Mar 15 14:05:25 2021 +0300

    all: imp code

commit bc610f8f438549e8c6b04c8a213b5422dda2aff5
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Fri Mar 12 20:00:14 2021 +0300

    all: imp code, err handling

internal/home/control.go

@@ -239,7 +239,7 @@ func handleHTTPSRedirect(w http.ResponseWriter, r *http.Request) (ok bool) {
 		}
 
 		httpsURL := &url.URL{
-			Scheme:   "https",
+			Scheme:   schemeHTTPS,
 			Host:     hostPort,
 			Path:     r.URL.Path,
 			RawQuery: r.URL.RawQuery,
@@ -255,7 +255,7 @@ func handleHTTPSRedirect(w http.ResponseWriter, r *http.Request) (ok bool) {
 	//
 	// See https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Access-Control-Allow-Origin.
 	originURL := &url.URL{
-		Scheme: "http",
+		Scheme: schemeHTTP,
 		Host:   r.Host,
 	}
 	w.Header().Set("Access-Control-Allow-Origin", originURL.String())

internal/home/controlfiltering.go

@@ -12,26 +12,31 @@ import (
 	"strings"
 	"time"
 
-	"github.com/AdguardTeam/AdGuardHome/internal/util"
 	"github.com/AdguardTeam/golibs/log"
 	"github.com/miekg/dns"
 )
 
-// isValidURL - return TRUE if URL or file path is valid
-func isValidURL(rawurl string) bool {
-	if filepath.IsAbs(rawurl) {
-		// this is a file path
-		return util.FileExists(rawurl)
+// validateFilterURL validates the filter list URL or file name.
+func validateFilterURL(urlStr string) (err error) {
+	if filepath.IsAbs(urlStr) {
+		_, err = os.Stat(urlStr)
+		if err != nil {
+			return fmt.Errorf("checking filter file: %w", err)
+		}
+
+		return nil
 	}
 
-	url, err := url.ParseRequestURI(rawurl)
+	url, err := url.ParseRequestURI(urlStr)
 	if err != nil {
-		return false // Couldn't even parse the rawurl
+		return fmt.Errorf("checking filter url: %w", err)
 	}
-	if len(url.Scheme) == 0 {
-		return false // No Scheme found
+
+	if s := url.Scheme; s != schemeHTTP && s != schemeHTTPS {
+		return fmt.Errorf("checking filter url: invalid scheme %q", s)
 	}
-	return true
+
+	return nil
 }
 
 type filterAddJSON struct {
@@ -48,8 +53,11 @@ func (f *Filtering) handleFilteringAddURL(w http.ResponseWriter, r *http.Request
 		return
 	}
 
-	if !isValidURL(fj.URL) {
-		http.Error(w, "Invalid URL or file path", http.StatusBadRequest)
+	err = validateFilterURL(fj.URL)
+	if err != nil {
+		msg := fmt.Sprintf("invalid url: %s", err)
+		http.Error(w, msg, http.StatusBadRequest)
+
 		return
 	}
 
@@ -168,8 +176,11 @@ func (f *Filtering) handleFilteringSetURL(w http.ResponseWriter, r *http.Request
 		return
 	}
 
-	if !isValidURL(fj.Data.URL) {
-		http.Error(w, "invalid URL or file path", http.StatusBadRequest)
+	err = validateFilterURL(fj.Data.URL)
+	if err != nil {
+		msg := fmt.Sprintf("invalid url: %s", err)
+		http.Error(w, msg, http.StatusBadRequest)
+
 		return
 	}
 

internal/home/home.go

@@ -570,8 +570,8 @@ func loadOptions() options {
 	return o
 }
 
-// prints IP addresses which user can use to open the admin interface
-// proto is either "http" or "https"
+// printHTTPAddresses prints the IP addresses which user can use to open the
+// admin interface.  proto is either schemeHTTP or schemeHTTPS.
 func printHTTPAddresses(proto string) {
 	tlsConf := tlsConfigSettings{}
 	if Context.tls != nil {
@@ -579,12 +579,12 @@ func printHTTPAddresses(proto string) {
 	}
 
 	port := strconv.Itoa(config.BindPort)
-	if proto == "https" {
+	if proto == schemeHTTPS {
 		port = strconv.Itoa(tlsConf.PortHTTPS)
 	}
 
 	var hostStr string
-	if proto == "https" && tlsConf.ServerName != "" {
+	if proto == schemeHTTPS && tlsConf.ServerName != "" {
 		if tlsConf.PortHTTPS == 443 {
 			log.Printf("Go to https://%s", tlsConf.ServerName)
 		} else {

internal/home/mobileconfig.go

@@ -58,7 +58,7 @@ func getMobileConfig(d dnsSettings) ([]byte, error) {
 		dspName = fmt.Sprintf("%s DoH", d.ServerName)
 
 		u := &url.URL{
-			Scheme: "https",
+			Scheme: schemeHTTPS,
 			Host:   d.ServerName,
 			Path:   "/dns-query",
 		}

internal/home/service.go

@@ -236,7 +236,7 @@ func handleServiceInstallCommand(s service.Service) {
 AdGuard Home is successfully installed and will automatically start on boot.
 There are a few more things that must be configured before you can use it.
 Click on the link below and follow the Installation Wizard steps to finish setup.`)
-		printHTTPAddresses("http")
+		printHTTPAddresses(schemeHTTP)
 	}
 }
 

internal/home/web.go

@@ -15,6 +15,12 @@ import (
 	"github.com/gobuffalo/packr"
 )
 
+// HTTP scheme constants.
+const (
+	schemeHTTP  = "http"
+	schemeHTTPS = "https"
+)
+
 const (
 	// readTimeout is the maximum duration for reading the entire request,
 	// including the body.
@@ -159,7 +165,7 @@ func (web *Web) Start() {
 
 	// this loop is used as an ability to change listening host and/or port
 	for !web.httpsServer.shutdown {
-		printHTTPAddresses("http")
+		printHTTPAddresses(schemeHTTP)
 		errs := make(chan error, 2)
 
 		hostStr := web.conf.BindHost.String()
@@ -256,7 +262,7 @@ func (web *Web) tlsServerLoop() {
 			WriteTimeout:      web.conf.WriteTimeout,
 		}
 
-		printHTTPAddresses("https")
+		printHTTPAddresses(schemeHTTPS)
 		err := web.httpsServer.server.ListenAndServeTLS("", "")
 		if err != http.ErrServerClosed {
 			cleanupAlways()