Pull request: all: imp code, decr cyclo

Updates #2646.

Squashed commit of the following:

commit c83c230f3d2c542d7b1a4bc0e1c503d5bbc16cb8
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Thu Mar 25 19:47:11 2021 +0300

    all: imp code, decr cyclo

internal/dnsforward/config.go

@@ -25,7 +25,7 @@ type FilteringConfig struct {
 	// --
 
 	// FilterHandler is an optional additional filtering callback.
-	FilterHandler func(clientAddr net.IP, clientID string, settings *dnsfilter.RequestFilteringSettings) `yaml:"-"`
+	FilterHandler func(clientAddr net.IP, clientID string, settings *dnsfilter.FilteringSettings) `yaml:"-"`
 
 	// GetCustomUpstreamByClient - a callback function that returns upstreams configuration
 	// based on the client IP address. Returns nil if there are no custom upstreams for the client

internal/dnsforward/dns.go

@@ -20,7 +20,7 @@ type dnsContext struct {
 	srv      *Server
 	proxyCtx *proxy.DNSContext
 	// setts are the filtering settings for the client.
-	setts     *dnsfilter.RequestFilteringSettings
+	setts     *dnsfilter.FilteringSettings
 	startTime time.Time
 	result    *dnsfilter.Result
 	// origResp is the response received from upstream.  It is set when the

internal/dnsforward/dnsforward_test.go

@@ -632,7 +632,7 @@ func TestClientRulesForCNAMEMatching(t *testing.T) {
 		TCPListenAddrs: []*net.TCPAddr{{}},
 		FilteringConfig: FilteringConfig{
 			ProtectionEnabled: true,
-			FilterHandler: func(_ net.IP, _ string, settings *dnsfilter.RequestFilteringSettings) {
+			FilterHandler: func(_ net.IP, _ string, settings *dnsfilter.FilteringSettings) {
 				settings.FilteringEnabled = false
 			},
 		},

internal/dnsforward/filter.go

@@ -32,7 +32,7 @@ func (s *Server) beforeRequestHandler(_ *proxy.Proxy, d *proxy.DNSContext) (bool
 
 // getClientRequestFilteringSettings looks up client filtering settings using
 // the client's IP address and ID, if any, from ctx.
-func (s *Server) getClientRequestFilteringSettings(ctx *dnsContext) *dnsfilter.RequestFilteringSettings {
+func (s *Server) getClientRequestFilteringSettings(ctx *dnsContext) *dnsfilter.FilteringSettings {
 	setts := s.dnsFilter.GetConfig()
 	setts.FilteringEnabled = true
 	if s.conf.FilterHandler != nil {