Pull request:* all: fix all staticcheck SA warnings

Merge in DNS/adguard-home from 2238-fix-static-analisys-warnings to master

Squashed commit of the following:

commit 721ca6fa1cbfdfe9d414e6ed52fec4a64653fb52
Author: Eugene Burkov <e.burkov@adguard.com>
Date:   Fri Oct 30 15:48:10 2020 +0300

    * all: fix all staticcheck SA warnings

    Closes #2238.

internal/dhcpd/dhcp_http.go

@@ -175,7 +175,7 @@ func (s *Server) handleDHCPSetConfig(w http.ResponseWriter, r *http.Request) {
 		v6conf.InterfaceName = newconfig.InterfaceName
 		v6conf.notify = s.onNotify
 		s6, err = v6Create(v6conf)
-		if s6 == nil {
+		if err != nil {
 			httpError(r, w, http.StatusBadRequest, "Invalid DHCPv6 configuration: %s", err)
 			return
 		}

internal/dhcpd/dhcpd_test.go

@@ -83,7 +83,6 @@ func TestIsValidSubnetMask(t *testing.T) {
 func TestNormalizeLeases(t *testing.T) {
 	dynLeases := []*Lease{}
 	staticLeases := []*Lease{}
-	leases := []*Lease{}
 
 	lease := &Lease{}
 	lease.HWAddr = []byte{1, 2, 3, 4}
@@ -100,7 +99,7 @@ func TestNormalizeLeases(t *testing.T) {
 	lease.HWAddr = []byte{2, 2, 3, 4}
 	staticLeases = append(staticLeases, lease)
 
-	leases = normalizeLeases(staticLeases, dynLeases)
+	leases := normalizeLeases(staticLeases, dynLeases)
 
 	assert.True(t, len(leases) == 3)
 	assert.True(t, bytes.Equal(leases[0].HWAddr, []byte{1, 2, 3, 4}))

internal/dhcpd/v6.go

@@ -45,6 +45,7 @@ func ip6InRange(start net.IP, ip net.IP) bool {
 	if len(start) != 16 {
 		return false
 	}
+	//lint:ignore SA1021 TODO(e.burkov): Ignore this for now, think about using masks.
 	if !bytes.Equal(start[:15], ip[:15]) {
 		return false
 	}

internal/dnsforward/dnsforward_test.go

@@ -815,12 +815,13 @@ func sendTestMessageAsync(t *testing.T, conn *dns.Conn, g *sync.WaitGroup) {
 	req := createGoogleATestMessage()
 	err := conn.WriteMsg(req)
 	if err != nil {
-		t.Fatalf("cannot write message: %s", err)
+		panic(fmt.Sprintf("cannot write message: %s", err))
+
 	}
 
 	res, err := conn.ReadMsg()
 	if err != nil {
-		t.Fatalf("cannot read response to message: %s", err)
+		panic(fmt.Sprintf("cannot read response to message: %s", err))
 	}
 	assertGoogleAResponse(t, res)
 }

internal/home/tls.go

@@ -307,7 +307,6 @@ func verifyCertChain(data *tlsConfigStatus, certChain string, serverName string)
 
 	// now do a more extended validation
 	var certs []*pem.Block // PEM-encoded certificates
-	var skippedBytes []string // skipped bytes
 
 	pemblock := []byte(certChain)
 	for {
@@ -318,10 +317,6 @@ func verifyCertChain(data *tlsConfigStatus, certChain string, serverName string)
 		}
 		if decoded.Type == "CERTIFICATE" {
 			certs = append(certs, decoded)
-		} else {
-			// ignore "this result of append is never used" warning
-			// nolint
-			skippedBytes = append(skippedBytes, decoded.Type)
 		}
 	}
 
@@ -388,7 +383,6 @@ func verifyCertChain(data *tlsConfigStatus, certChain string, serverName string)
 func validatePkey(data *tlsConfigStatus, pkey string) error {
 	// now do a more extended validation
 	var key *pem.Block // PEM-encoded certificates
-	var skippedBytes []string // skipped bytes
 
 	// go through all pem blocks, but take first valid pem block and drop the rest
 	pemblock := []byte(pkey)
@@ -401,10 +395,6 @@ func validatePkey(data *tlsConfigStatus, pkey string) error {
 		if decoded.Type == "PRIVATE KEY" || strings.HasSuffix(decoded.Type, " PRIVATE KEY") {
 			key = decoded
 			break
-		} else {
-			// ignore "this result of append is never used"
-			// nolint
-			skippedBytes = append(skippedBytes, decoded.Type)
 		}
 	}
 

internal/querylog/decode_test.go

@@ -15,7 +15,7 @@ func TestJSON(t *testing.T) {
 	assert.Equal(t, "keystr", k)
 	assert.Equal(t, "val", v)
 
-	k, v, jtype = readJSON(&s)
+	k, _, jtype = readJSON(&s)
 	assert.Equal(t, jtype, int32(jsonTObj))
 	assert.Equal(t, "obj", k)
 
@@ -29,6 +29,6 @@ func TestJSON(t *testing.T) {
 	assert.Equal(t, "keyint", k)
 	assert.Equal(t, "123456", v)
 
-	k, v, jtype = readJSON(&s)
+	_, _, jtype = readJSON(&s)
 	assert.True(t, jtype == jsonTErr)
 }

internal/util/pprof.go

@@ -64,6 +64,7 @@ package util
 import (
 	"bufio"
 	"bytes"
+	"context"
 	"fmt"
 	"html/template"
 	"io"
@@ -94,14 +95,11 @@ func PProfRegisterWebHandlers(mux *http.ServeMux) {
 func Cmdline(w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("X-Content-Type-Options", "nosniff")
 	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
-	fmt.Fprintf(w, strings.Join(os.Args, "\x00"))
+	fmt.Fprint(w, strings.Join(os.Args, "\x00"))
 }
 
-func sleep(w http.ResponseWriter, d time.Duration) {
-	var clientGone <-chan bool
-	if cn, ok := w.(http.CloseNotifier); ok {
-		clientGone = cn.CloseNotify()
-	}
+func sleep(ctx context.Context, d time.Duration) {
+	clientGone := ctx.Done()
 	select {
 	case <-time.After(d):
 	case <-clientGone:
@@ -146,7 +144,7 @@ func Profile(w http.ResponseWriter, r *http.Request) {
 			fmt.Sprintf("Could not enable CPU profiling: %s", err))
 		return
 	}
-	sleep(w, time.Duration(sec)*time.Second)
+	sleep(r.Context(), time.Duration(sec)*time.Second)
 	pprof.StopCPUProfile()
 }
 
@@ -175,7 +173,7 @@ func Trace(w http.ResponseWriter, r *http.Request) {
 			fmt.Sprintf("Could not enable tracing: %s", err))
 		return
 	}
-	sleep(w, time.Duration(sec*float64(time.Second)))
+	sleep(r.Context(), time.Duration(sec*float64(time.Second)))
 	trace.Stop()
 }