Pull request: proxy: imp timeout logs

Updates AdguardTeam/AdGuardHome#4128.

Squashed commit of the following:

commit 9211b05
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Tue Feb 15 16:28:23 2022 +0300

    proxy: imp timeout logs

proxy/server.go

@@ -5,7 +5,6 @@ import (
 	"net"
 	"time"
 
-	"github.com/AdguardTeam/golibs/errors"
 	"github.com/AdguardTeam/golibs/log"
 	"github.com/miekg/dns"
 )
@@ -166,19 +165,10 @@ func (p *Proxy) respond(d *DNSContext) {
 	}
 
 	if err != nil {
-		if isNonCriticalError(err) {
-			// We're probably restarting, so log this with the debug level.
-			log.Debug("responding to %s request: %s", d.Proto, err)
-		} else {
-			log.Info("responding to %s request: %s", d.Proto, err)
-		}
+		logWithNonCrit(err, fmt.Sprintf("responding %s request", d.Proto))
 	}
 }
 
-func isNonCriticalError(err error) (ok bool) {
-	return isEPIPE(err) || errors.Is(err, net.ErrClosed)
-}
-
 // Set TTL value of all records according to our settings
 func (p *Proxy) setMinMaxTTL(r *dns.Msg) {
 	for _, rr := range r.Answer {

proxy/server_tcp.go

@@ -122,15 +122,15 @@ func (p *Proxy) handleTCPConnection(conn net.Conn, proto Proto) {
 
 		err = p.handleDNSRequest(d)
 		if err != nil {
-			log.Error("handling tcp: handling %s request: %s", d.Proto, err)
+			logWithNonCrit(err, fmt.Sprintf("handling tcp: handling %s request", d.Proto))
 		}
 	}
 }
 
 // logWithNonCrit logs the error on the appropriate level depending on whether
 // err is a critical error or not.
 func logWithNonCrit(err error, msg string) {
-	if errors.Is(err, io.EOF) || errors.Is(err, net.ErrClosed) {
+	if errors.Is(err, io.EOF) || errors.Is(err, net.ErrClosed) || isEPIPE(err) {
 		log.Debug("%s: connection is closed; original error: %s", msg, err)
 	} else if netErr := net.Error(nil); errors.As(err, &netErr) && netErr.Timeout() {
 		log.Debug("%s: connection timed out; original error: %s", msg, err)