Pull request: all: fix some races

Updates #3087.

Squashed commit of the following:

commit e888ce524f286f3c34e14e0086336b65a95fa020
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Mon May 17 16:34:10 2021 +0300

    all: fix some races

internal/home/control.go

@@ -133,14 +133,21 @@ func handleStatus(w http.ResponseWriter, _ *http.Request) {
 		return
 	}
 
-	resp := statusResponse{
-		DNSAddrs:  dnsAddrs,
-		DNSPort:   config.DNS.Port,
-		HTTPPort:  config.BindPort,
-		IsRunning: isRunning(),
-		Version:   version.Version(),
-		Language:  config.Language,
-	}
+	var resp statusResponse
+
+	func() {
+		config.RLock()
+		defer config.RUnlock()
+
+		resp = statusResponse{
+			DNSAddrs:  dnsAddrs,
+			DNSPort:   config.DNS.Port,
+			HTTPPort:  config.BindPort,
+			IsRunning: isRunning(),
+			Version:   version.Version(),
+			Language:  config.Language,
+		}
+	}()
 
 	var c *dnsforward.FilteringConfig
 	if Context.dnsServer != nil {

internal/home/dns.go

@@ -319,6 +319,9 @@ func applyAdditionalFiltering(clientAddr net.IP, clientID string, setts *dnsfilt
 }
 
 func startDNSServer() error {
+	config.Lock()
+	defer config.Unlock()
+
 	if isRunning() {
 		return fmt.Errorf("unable to start forwarding DNS server: Already running")
 	}

internal/home/i18n.go

@@ -86,7 +86,13 @@ func handleI18nChangeLanguage(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	config.Language = language
+	func() {
+		config.Lock()
+		defer config.Unlock()
+
+		config.Language = language
+	}()
+
 	onConfigModified()
 	returnOK(w)
 }