Pull request: all: fmt, imp logs

Updates AdguardTeam/AdGuardHome#4065.

Squashed commit of the following:

commit 89b65c9
Author: Ainar Garipov <[email protected]>
Date:   Mon Jan 17 18:40:50 2022 +0300

    proxy: imp code

commit 344c528
Author: Ainar Garipov <[email protected]>
Date:   Mon Jan 17 18:20:53 2022 +0300

    all: fmt, imp logs

main.go

@@ -216,7 +216,7 @@ func run(options *Options) {
 		log.SetLevel(log.DEBUG)
 	}
 	if options.LogOutput != "" {
-		file, err := os.OpenFile(options.LogOutput, os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0644)
+		file, err := os.OpenFile(options.LogOutput, os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0o644)
 		if err != nil {
 			log.Fatalf("cannot create a log file: %s", err)
 		}

proxy/cache.go

@@ -399,7 +399,7 @@ func minTTL(h *dns.RR_Header, ttl uint32) uint32 {
 
 // Updates a given TTL to fall within the range specified by the cacheMinTTL and
 // cacheMaxTTL settings.
-func respectTTLOverrides(ttl uint32, cacheMinTTL uint32, cacheMaxTTL uint32) uint32 {
+func respectTTLOverrides(ttl, cacheMinTTL, cacheMaxTTL uint32) uint32 {
 	if ttl < cacheMinTTL {
 		return cacheMinTTL
 	}

proxy/cache_test.go

@@ -569,7 +569,7 @@ type testCase struct {
 
 // requireEqualMsgs asserts the messages are equal except their ID, Rdlength, and
 // the case of questions.
-func requireEqualMsgs(t *testing.T, expected *dns.Msg, actual *dns.Msg) {
+func requireEqualMsgs(t *testing.T, expected, actual *dns.Msg) {
 	t.Helper()
 
 	temp := *expected

proxy/helpers.go

@@ -67,7 +67,7 @@ func genSOA(request *dns.Msg, retry uint32) []dns.RR {
 }
 
 // parseECS parses the EDNS client subnet option from m.
-func parseECS(m *dns.Msg) (addr net.IP, mask uint8, scope uint8) {
+func parseECS(m *dns.Msg) (addr net.IP, mask, scope uint8) {
 	opt := m.IsEdns0()
 	if opt == nil {
 		return nil, 0, 0

proxy/proxy_test.go

@@ -126,8 +126,9 @@ func TestProxy_Resolve_dnssecCache(t *testing.T) {
 
 	txtDataChunkNum := txtDataLen / txtDataChunkLen
 	if txtDataLen%txtDataChunkLen > 0 {
-		txtDataChunkNum += 1
+		txtDataChunkNum++
 	}
+
 	txts := make([]string, txtDataChunkNum)
 	randData := make([]byte, txtDataLen)
 	n, err := rand.Read(randData)

proxy/server_tcp.go

@@ -69,16 +69,16 @@ func (p *Proxy) tcpPacketLoop(l net.Listener, proto Proto, requestGoroutinesSema
 	}
 }
 
-// handleTCPConnection starts a loop that handles an incoming TCP connection
-// proto is either "tcp" or "tls"
+// handleTCPConnection starts a loop that handles an incoming TCP connection.
+// proto must be either ProtoTCP or ProtoTLS.
 func (p *Proxy) handleTCPConnection(conn net.Conn, proto Proto) {
 	defer log.OnPanic("proxy.handleTCPConnection")
 
 	log.Tracef("handling tcp: started handling %s request from %s", proto, conn.RemoteAddr())
 	defer func() {
 		err := conn.Close()
 		if err != nil {
-			log.Error("handling tcp: closing conn: %s", err)
+			logWithClosed(err, "handling tcp: closing conn")
 		}
 	}()
 
@@ -92,16 +92,12 @@ func (p *Proxy) handleTCPConnection(conn net.Conn, proto Proto) {
 		err := conn.SetDeadline(time.Now().Add(defaultTimeout))
 		if err != nil {
 			// Consider deadline errors non-critical.
-			log.Error("handling tcp: setting deadline: %s", err)
+			logWithClosed(err, "handling tcp: setting deadline")
 		}
 
 		packet, err := proxyutil.ReadPrefixed(conn)
 		if err != nil {
-			if errors.Is(err, io.EOF) || errors.Is(err, net.ErrClosed) {
-				log.Debug("handling tcp: connection closed: %s", err)
-			} else {
-				log.Error("handling tcp: reading msg: %s", err)
-			}
+			logWithClosed(err, "handling tcp: reading msg")
 
 			break
 		}
@@ -125,6 +121,16 @@ func (p *Proxy) handleTCPConnection(conn net.Conn, proto Proto) {
 	}
 }
 
+// logWithClosed logs the error on the appropriate level depending on whether
+// err is an error about a closed connection.
+func logWithClosed(err error, msg string) {
+	if errors.Is(err, io.EOF) || errors.Is(err, net.ErrClosed) {
+		log.Debug("%s: connection is closed; original error: %s", msg, err)
+	} else {
+		log.Error("%s: %s", msg, err)
+	}
+}
+
 // Writes a response to the TCP (or TLS) client
 func (p *Proxy) respondTCP(d *DNSContext) error {
 	resp := d.Res

proxyutil/helpers.go

@@ -85,7 +85,7 @@ func SortIPAddrs(ipAddrs []net.IPAddr) []net.IPAddr {
 	return ipAddrs
 }
 
-func compareIPAddrs(left net.IPAddr, right net.IPAddr) int {
+func compareIPAddrs(left, right net.IPAddr) int {
 	l4 := left.IP.To4()
 	r4 := right.IP.To4()
 	if l4 != nil && r4 == nil {

proxyutil/udp_unix.go

@@ -25,9 +25,7 @@ const (
 
 // udpGetOOBSize obtains the destination IP from OOB data.
 func udpGetOOBSize() (oobSize int) {
-	l4, l6 :=
-		len(ipv4.NewControlMessage(ipv4Flags)),
-		len(ipv6.NewControlMessage(ipv6Flags))
+	l4, l6 := len(ipv4.NewControlMessage(ipv4Flags)), len(ipv6.NewControlMessage(ipv6Flags))
 
 	if l4 >= l6 {
 		return l4