Fix tests and linters

firewall/interception/interception.go

@@ -25,7 +25,7 @@ func Start() error {
 		return nil
 	}
 
-	var inputPackets = Packets
+	inputPackets := Packets
 	if packetMetricsDestination != "" {
 		go metrics.writeMetrics()
 		inputPackets = make(chan packet.Packet)

firewall/interception/introspection.go

@@ -58,7 +58,9 @@ func (pm *packetMetrics) writeMetrics() {
 		log.Errorf("Failed to create packet metrics file: %s", err)
 		return
 	}
-	defer f.Close()
+	defer func() {
+		_ = f.Close()
+	}()
 
 	for {
 		select {

firewall/interception/nfq/nfq.go

@@ -1,4 +1,4 @@
-// +build linux
+// go:build linux
 
 // Package nfq contains a nfqueue library experiment.
 package nfq
@@ -10,15 +10,15 @@ import (
 	"sync/atomic"
 	"time"
 
-	"github.com/safing/portbase/log"
-	pmpacket "github.com/safing/portmaster/network/packet"
+	"github.com/florianl/go-nfqueue"
 	"github.com/tevino/abool"
 	"golang.org/x/sys/unix"
 
-	"github.com/florianl/go-nfqueue"
+	"github.com/safing/portbase/log"
+	pmpacket "github.com/safing/portmaster/network/packet"
 )
 
-// Queue wraps a nfqueue
+// Queue wraps a nfqueue.
 type Queue struct {
 	id                   uint16
 	afFamily             uint8
@@ -32,7 +32,7 @@ type Queue struct {
 }
 
 func (q *Queue) getNfq() *nfqueue.Nfqueue {
-	return q.nf.Load().(*nfqueue.Nfqueue)
+	return q.nf.Load().(*nfqueue.Nfqueue) //nolint:forcetypeassert // TODO: Check.
 }
 
 // New opens a new nfQueue.
@@ -112,7 +112,7 @@ func (q *Queue) open(ctx context.Context) error {
 	}
 
 	if err := nf.RegisterWithErrorFunc(ctx, q.packetHandler(ctx), q.handleError); err != nil {
-		defer nf.Close()
+		_ = nf.Close()
 		return err
 	}
 
@@ -124,7 +124,7 @@ func (q *Queue) open(ctx context.Context) error {
 func (q *Queue) handleError(e error) int {
 	// embedded interface is required to work-around some
 	// dep-vendoring weirdness
-	if opError, ok := e.(interface {
+	if opError, ok := e.(interface { //nolint:errorlint // TODO: Check if we can remove workaround.
 		Timeout() bool
 		Temporary() bool
 	}); ok {
@@ -153,7 +153,7 @@ func (q *Queue) handleError(e error) int {
 
 	// Close the existing socket
 	if nf := q.getNfq(); nf != nil {
-		nf.Close()
+		_ = nf.Close()
 	}
 
 	// Trigger a restart of the queue

firewall/interception/nfq/packet.go

@@ -1,4 +1,4 @@
-// +build linux
+// go:build linux
 
 package nfq
 
@@ -8,9 +8,9 @@ import (
 	"sync/atomic"
 	"time"
 
+	"github.com/florianl/go-nfqueue"
 	"github.com/tevino/abool"
 
-	"github.com/florianl/go-nfqueue"
 	"github.com/safing/portbase/log"
 	pmpacket "github.com/safing/portmaster/network/packet"
 )
@@ -104,7 +104,7 @@ func (pkt *packet) setMark(mark int) error {
 		if err := pkt.queue.getNfq().SetVerdictWithMark(pkt.pktID, nfqueue.NfAccept, mark); err != nil {
 			// embedded interface is required to work-around some
 			// dep-vendoring weirdness
-			if opErr, ok := err.(interface {
+			if opErr, ok := err.(interface { //nolint:errorlint // TODO: Check if we can remove workaround.
 				Timeout() bool
 				Temporary() bool
 			}); ok {

firewall/interception/nfqueue_linux.go

@@ -44,7 +44,6 @@ type nfQueue interface {
 }
 
 func init() {
-
 	v4chains = []string{
 		"mangle C170",
 		"mangle C171",
@@ -128,7 +127,6 @@ func init() {
 	// Reverse because we'd like to insert in a loop
 	_ = sort.Reverse(sort.StringSlice(v4once)) // silence vet (sort is used just like in the docs)
 	_ = sort.Reverse(sort.StringSlice(v6once)) // silence vet (sort is used just like in the docs)
-
 }
 
 func activateNfqueueFirewall() error {
@@ -241,7 +239,7 @@ func StartNfqueueInterception(packets chan<- packet.Packet) (err error) {
 	err = activateNfqueueFirewall()
 	if err != nil {
 		_ = Stop()
-		return fmt.Errorf("could not initialize nfqueue: %s", err)
+		return fmt.Errorf("could not initialize nfqueue: %w", err)
 	}
 
 	out4Queue, err = nfq.New(17040, false)
@@ -288,7 +286,7 @@ func StopNfqueueInterception() error {
 
 	err := DeactivateNfqueueFirewall()
 	if err != nil {
-		return fmt.Errorf("interception: error while deactivating nfqueue: %s", err)
+		return fmt.Errorf("interception: error while deactivating nfqueue: %w", err)
 	}
 
 	return nil