all: Remove lib/util package (#9049)

Grab-bag packages are nasty, this cleans it up a little by splitting it
into topical packages sempahore, netutil, stringutil, structutil.

36 files changed, 414 insertions, 385 deletions

diff --git a/lib/api/api_test.go b/lib/api/api_test.go
index 6d1abfecb..be85ed6ee 100644
--- a/lib/api/api_test.go
+++ b/lib/api/api_test.go
@@ -44,8 +44,8 @@ import (
 	"github.com/syncthing/syncthing/lib/sync"
 	"github.com/syncthing/syncthing/lib/tlsutil"
 	"github.com/syncthing/syncthing/lib/ur"
-	"github.com/syncthing/syncthing/lib/util"
 	"github.com/thejerf/suture/v4"
+	"golang.org/x/exp/slices"
 )
 
 var (
@@ -1313,7 +1313,7 @@ func TestBrowse(t *testing.T) {
 
 	for _, tc := range cases {
 		ret := browseFiles(ffs, tc.current)
-		if !util.EqualStrings(ret, tc.returns) {
+		if !slices.Equal(ret, tc.returns) {
 			t.Errorf("browseFiles(%q) => %q, expected %q", tc.current, ret, tc.returns)
 		}
 	}
diff --git a/lib/api/confighandler.go b/lib/api/confighandler.go
index f26ba1c86..5abc1f055 100644
--- a/lib/api/confighandler.go
+++ b/lib/api/confighandler.go
@@ -15,7 +15,7 @@ import (
 
 	"github.com/syncthing/syncthing/lib/config"
 	"github.com/syncthing/syncthing/lib/protocol"
-	"github.com/syncthing/syncthing/lib/util"
+	"github.com/syncthing/syncthing/lib/structutil"
 )
 
 type configMuxBuilder struct {
@@ -212,7 +212,7 @@ func (c *configMuxBuilder) registerDefaultFolder(path string) {
 
 	c.HandlerFunc(http.MethodPut, path, func(w http.ResponseWriter, r *http.Request) {
 		var cfg config.FolderConfiguration
-		util.SetDefaults(&cfg)
+		structutil.SetDefaults(&cfg)
 		c.adjustFolder(w, r, cfg, true)
 	})
 
@@ -228,7 +228,7 @@ func (c *configMuxBuilder) registerDefaultDevice(path string) {
 
 	c.HandlerFunc(http.MethodPut, path, func(w http.ResponseWriter, r *http.Request) {
 		var cfg config.DeviceConfiguration
-		util.SetDefaults(&cfg)
+		structutil.SetDefaults(&cfg)
 		c.adjustDevice(w, r, cfg, true)
 	})
 
@@ -266,7 +266,7 @@ func (c *configMuxBuilder) registerOptions(path string) {
 
 	c.HandlerFunc(http.MethodPut, path, func(w http.ResponseWriter, r *http.Request) {
 		var cfg config.OptionsConfiguration
-		util.SetDefaults(&cfg)
+		structutil.SetDefaults(&cfg)
 		c.adjustOptions(w, r, cfg)
 	})
 
@@ -282,7 +282,7 @@ func (c *configMuxBuilder) registerLDAP(path string) {
 
 	c.HandlerFunc(http.MethodPut, path, func(w http.ResponseWriter, r *http.Request) {
 		var cfg config.LDAPConfiguration
-		util.SetDefaults(&cfg)
+		structutil.SetDefaults(&cfg)
 		c.adjustLDAP(w, r, cfg)
 	})
 
@@ -298,7 +298,7 @@ func (c *configMuxBuilder) registerGUI(path string) {
 
 	c.HandlerFunc(http.MethodPut, path, func(w http.ResponseWriter, r *http.Request) {
 		var cfg config.GUIConfiguration
-		util.SetDefaults(&cfg)
+		structutil.SetDefaults(&cfg)
 		c.adjustGUI(w, r, cfg)
 	})
 
diff --git a/lib/config/config.go b/lib/config/config.go
index 8787cf8b5..4f02085fc 100644
--- a/lib/config/config.go
+++ b/lib/config/config.go
@@ -16,14 +16,16 @@ import (
 	"net"
 	"net/url"
 	"os"
+	"reflect"
 	"sort"
 	"strconv"
 	"strings"
 
 	"github.com/syncthing/syncthing/lib/build"
 	"github.com/syncthing/syncthing/lib/fs"
+	"github.com/syncthing/syncthing/lib/netutil"
 	"github.com/syncthing/syncthing/lib/protocol"
-	"github.com/syncthing/syncthing/lib/util"
+	"github.com/syncthing/syncthing/lib/structutil"
 )
 
 const (
@@ -42,9 +44,9 @@ var (
 	// "consumer" of the configuration as we don't want these saved to the
 	// config.
 	DefaultListenAddresses = []string{
-		util.Address("tcp", net.JoinHostPort("0.0.0.0", strconv.Itoa(DefaultTCPPort))),
+		netutil.AddressURL("tcp", net.JoinHostPort("0.0.0.0", strconv.Itoa(DefaultTCPPort))),
 		"dynamic+https://relays.syncthing.net/endpoint",
-		util.Address("quic", net.JoinHostPort("0.0.0.0", strconv.Itoa(DefaultQUICPort))),
+		netutil.AddressURL("quic", net.JoinHostPort("0.0.0.0", strconv.Itoa(DefaultQUICPort))),
 	}
 	DefaultGUIPort = 8384
 	// DefaultDiscoveryServersV4 should be substituted when the configuration
@@ -101,7 +103,7 @@ func New(myID protocol.DeviceID) Configuration {
 
 	cfg.Options.UnackedNotificationIDs = []string{"authenticationUserAndPassword"}
 
-	util.SetDefaults(&cfg)
+	structutil.SetDefaults(&cfg)
 
 	// Can't happen.
 	if err := cfg.prepare(myID); err != nil {
@@ -127,9 +129,9 @@ func (cfg *Configuration) ProbeFreePorts() error {
 		cfg.Options.RawListenAddresses = []string{"default"}
 	} else {
 		cfg.Options.RawListenAddresses = []string{
-			util.Address("tcp", net.JoinHostPort("0.0.0.0", strconv.Itoa(port))),
+			netutil.AddressURL("tcp", net.JoinHostPort("0.0.0.0", strconv.Itoa(port))),
 			"dynamic+https://relays.syncthing.net/endpoint",
-			util.Address("quic", net.JoinHostPort("0.0.0.0", strconv.Itoa(port))),
+			netutil.AddressURL("quic", net.JoinHostPort("0.0.0.0", strconv.Itoa(port))),
 		}
 	}
 
@@ -144,7 +146,7 @@ type xmlConfiguration struct {
 func ReadXML(r io.Reader, myID protocol.DeviceID) (Configuration, int, error) {
 	var cfg xmlConfiguration
 
-	util.SetDefaults(&cfg)
+	structutil.SetDefaults(&cfg)
 
 	if err := xml.NewDecoder(r).Decode(&cfg); err != nil {
 		return Configuration{}, 0, err
@@ -166,7 +168,7 @@ func ReadJSON(r io.Reader, myID protocol.DeviceID) (Configuration, error) {
 
 	var cfg Configuration
 
-	util.SetDefaults(&cfg)
+	structutil.SetDefaults(&cfg)
 
 	if err := json.Unmarshal(bs, &cfg); err != nil {
 		return Configuration{}, err
@@ -259,7 +261,7 @@ func (cfg *Configuration) prepare(myID protocol.DeviceID) error {
 
 	cfg.removeDeprecatedProtocols()
 
-	util.FillNilExceptDeprecated(cfg)
+	structutil.FillNilExceptDeprecated(cfg)
 
 	// TestIssue1750 relies on migrations happening after preparing options.
 	cfg.applyMigrations()
@@ -636,7 +638,7 @@ func (defaults *Defaults) prepare(myID protocol.DeviceID, existingDevices map[pr
 }
 
 func ensureZeroForNodefault(empty interface{}, target interface{}) {
-	util.CopyMatchingTag(empty, target, "nodefault", func(v string) bool {
+	copyMatchingTag(empty, target, "nodefault", func(v string) bool {
 		if len(v) > 0 && v != "true" {
 			panic(fmt.Sprintf(`unexpected tag value: %s. expected untagged or "true"`, v))
 		}
@@ -644,6 +646,36 @@ func ensureZeroForNodefault(empty interface{}, target interface{}) {
 	})
 }
 
+// copyMatchingTag copies fields tagged tag:"value" from "from" struct onto "to" struct.
+func copyMatchingTag(from interface{}, to interface{}, tag string, shouldCopy func(value string) bool) {
+	fromStruct := reflect.ValueOf(from).Elem()
+	fromType := fromStruct.Type()
+
+	toStruct := reflect.ValueOf(to).Elem()
+	toType := toStruct.Type()
+
+	if fromType != toType {
+		panic(fmt.Sprintf("non equal types: %s != %s", fromType, toType))
+	}
+
+	for i := 0; i < toStruct.NumField(); i++ {
+		fromField := fromStruct.Field(i)
+		toField := toStruct.Field(i)
+
+		if !toField.CanSet() {
+			// Unexported fields
+			continue
+		}
+
+		structTag := toType.Field(i).Tag
+
+		v := structTag.Get(tag)
+		if shouldCopy(v) {
+			toField.Set(fromField)
+		}
+	}
+}
+
 func (i Ignores) Copy() Ignores {
 	out := Ignores{Lines: make([]string, len(i.Lines))}
 	copy(out.Lines, i.Lines)
diff --git a/lib/config/config_test.go b/lib/config/config_test.go
index e0d6ef22d..241cc2b59 100644
--- a/lib/config/config_test.go
+++ b/lib/config/config_test.go
@@ -1597,3 +1597,61 @@ func handleFile(name string) {
 	fd.Write(origin)
 	fd.Close()
 }
+
+func TestCopyMatching(t *testing.T) {
+	type Nested struct {
+		A int
+	}
+	type Test struct {
+		CopyA  int
+		CopyB  []string
+		CopyC  Nested
+		CopyD  *Nested
+		NoCopy int `restart:"true"`
+	}
+
+	from := Test{
+		CopyA: 1,
+		CopyB: []string{"friend", "foe"},
+		CopyC: Nested{
+			A: 2,
+		},
+		CopyD: &Nested{
+			A: 3,
+		},
+		NoCopy: 4,
+	}
+
+	to := Test{
+		CopyA: 11,
+		CopyB: []string{"foot", "toe"},
+		CopyC: Nested{
+			A: 22,
+		},
+		CopyD: &Nested{
+			A: 33,
+		},
+		NoCopy: 44,
+	}
+
+	// Copy empty fields
+	copyMatchingTag(&from, &to, "restart", func(v string) bool {
+		return v != "true"
+	})
+
+	if to.CopyA != 1 {
+		t.Error("CopyA")
+	}
+	if len(to.CopyB) != 2 || to.CopyB[0] != "friend" || to.CopyB[1] != "foe" {
+		t.Error("CopyB")
+	}
+	if to.CopyC.A != 2 {
+		t.Error("CopyC")
+	}
+	if to.CopyD.A != 3 {
+		t.Error("CopyC")
+	}
+	if to.NoCopy != 44 {
+		t.Error("NoCopy")
+	}
+}
diff --git a/lib/config/folderconfiguration.go b/lib/config/folderconfiguration.go
index d6e076727..3079c0f4c 100644
--- a/lib/config/folderconfiguration.go
+++ b/lib/config/folderconfiguration.go
@@ -21,7 +21,6 @@ import (
 	"github.com/syncthing/syncthing/lib/db"
 	"github.com/syncthing/syncthing/lib/fs"
 	"github.com/syncthing/syncthing/lib/protocol"
-	"github.com/syncthing/syncthing/lib/util"
 )
 
 var (
@@ -244,7 +243,7 @@ func (f FolderConfiguration) RequiresRestartOnly() FolderConfiguration {
 	// copier, yet should not cause a restart.
 
 	blank := FolderConfiguration{}
-	util.CopyMatchingTag(&blank, &copy, "restart", func(v string) bool {
+	copyMatchingTag(&blank, &copy, "restart", func(v string) bool {
 		if len(v) > 0 && v != "false" {
 			panic(fmt.Sprintf(`unexpected tag value: %s. expected untagged or "false"`, v))
 		}
diff --git a/lib/config/migrations.go b/lib/config/migrations.go
index 5bafb4701..82f54d566 100644
--- a/lib/config/migrations.go
+++ b/lib/config/migrations.go
@@ -17,8 +17,8 @@ import (
 
 	"github.com/syncthing/syncthing/lib/build"
 	"github.com/syncthing/syncthing/lib/fs"
+	"github.com/syncthing/syncthing/lib/netutil"
 	"github.com/syncthing/syncthing/lib/upgrade"
-	"github.com/syncthing/syncthing/lib/util"
 )
 
 // migrations is the set of config migration functions, with their target
@@ -197,11 +197,11 @@ func migrateToConfigV24(cfg *Configuration) {
 }
 
 func migrateToConfigV23(cfg *Configuration) {
-	permBits := fs.FileMode(0777)
+	permBits := fs.FileMode(0o777)
 	if build.IsWindows {
 		// Windows has no umask so we must chose a safer set of bits to
 		// begin with.
-		permBits = 0700
+		permBits = 0o700
 	}
 
 	// Upgrade code remains hardcoded for .stfolder despite configurable
@@ -391,14 +391,14 @@ func migrateToConfigV12(cfg *Configuration) {
 	// Change listen address schema
 	for i, addr := range cfg.Options.RawListenAddresses {
 		if len(addr) > 0 && !strings.HasPrefix(addr, "tcp://") {
-			cfg.Options.RawListenAddresses[i] = util.Address("tcp", addr)
+			cfg.Options.RawListenAddresses[i] = netutil.AddressURL("tcp", addr)
 		}
 	}
 
 	for i, device := range cfg.Devices {
 		for j, addr := range device.Addresses {
 			if addr != "dynamic" && addr != "" {
-				cfg.Devices[i].Addresses[j] = util.Address("tcp", addr)
+				cfg.Devices[i].Addresses[j] = netutil.AddressURL("tcp", addr)
 			}
 		}
 	}
diff --git a/lib/config/optionsconfiguration.go b/lib/config/optionsconfiguration.go
index 95d75416f..27e153790 100644
--- a/lib/config/optionsconfiguration.go
+++ b/lib/config/optionsconfiguration.go
@@ -12,7 +12,8 @@ import (
 
 	"github.com/syncthing/syncthing/lib/protocol"
 	"github.com/syncthing/syncthing/lib/rand"
-	"github.com/syncthing/syncthing/lib/util"
+	"github.com/syncthing/syncthing/lib/stringutil"
+	"github.com/syncthing/syncthing/lib/structutil"
 )
 
 func (opts OptionsConfiguration) Copy() OptionsConfiguration {
@@ -29,10 +30,10 @@ func (opts OptionsConfiguration) Copy() OptionsConfiguration {
 }
 
 func (opts *OptionsConfiguration) prepare(guiPWIsSet bool) {
-	util.FillNilSlices(opts)
+	structutil.FillNilSlices(opts)
 
-	opts.RawListenAddresses = util.UniqueTrimmedStrings(opts.RawListenAddresses)
-	opts.RawGlobalAnnServers = util.UniqueTrimmedStrings(opts.RawGlobalAnnServers)
+	opts.RawListenAddresses = stringutil.UniqueTrimmedStrings(opts.RawListenAddresses)
+	opts.RawGlobalAnnServers = stringutil.UniqueTrimmedStrings(opts.RawGlobalAnnServers)
 
 	// Very short reconnection intervals are annoying
 	if opts.ReconnectIntervalS < 5 {
@@ -71,7 +72,7 @@ func (opts *OptionsConfiguration) prepare(guiPWIsSet bool) {
 func (opts OptionsConfiguration) RequiresRestartOnly() OptionsConfiguration {
 	optsCopy := opts
 	blank := OptionsConfiguration{}
-	util.CopyMatchingTag(&blank, &optsCopy, "restart", func(v string) bool {
+	copyMatchingTag(&blank, &optsCopy, "restart", func(v string) bool {
 		if len(v) > 0 && v != "true" {
 			panic(fmt.Sprintf(`unexpected tag value: %s. Expected untagged or "true"`, v))
 		}
@@ -94,7 +95,7 @@ func (opts OptionsConfiguration) ListenAddresses() []string {
 			addresses = append(addresses, addr)
 		}
 	}
-	return util.UniqueTrimmedStrings(addresses)
+	return stringutil.UniqueTrimmedStrings(addresses)
 }
 
 func (opts OptionsConfiguration) StunServers() []string {
@@ -116,7 +117,7 @@ func (opts OptionsConfiguration) StunServers() []string {
 		}
 	}
 
-	addresses = util.UniqueTrimmedStrings(addresses)
+	addresses = stringutil.UniqueTrimmedStrings(addresses)
 
 	return addresses
 }
@@ -135,7 +136,7 @@ func (opts OptionsConfiguration) GlobalDiscoveryServers() []string {
 			servers = append(servers, srv)
 		}
 	}
-	return util.UniqueTrimmedStrings(servers)
+	return stringutil.UniqueTrimmedStrings(servers)
 }
 
 func (opts OptionsConfiguration) MaxFolderConcurrency() int {
diff --git a/lib/config/size_test.go b/lib/config/size_test.go
index d47bdde34..ab218abcc 100644
--- a/lib/config/size_test.go
+++ b/lib/config/size_test.go
@@ -10,7 +10,7 @@ import (
 	"testing"
 
 	"github.com/syncthing/syncthing/lib/fs"
-	"github.com/syncthing/syncthing/lib/util"
+	"github.com/syncthing/syncthing/lib/structutil"
 )
 
 type TestStruct struct {
@@ -20,7 +20,7 @@ type TestStruct struct {
 func TestSizeDefaults(t *testing.T) {
 	x := &TestStruct{}
 
-	util.SetDefaults(x)
+	structutil.SetDefaults(x)
 
 	if !x.Size.Percentage() {
 		t.Error("not percentage")
diff --git a/lib/config/versioningconfiguration.go b/lib/config/versioningconfiguration.go
index 2f7f87bc7..05355e746 100644
--- a/lib/config/versioningconfiguration.go
+++ b/lib/config/versioningconfiguration.go
@@ -12,7 +12,7 @@ import (
 	"sort"
 
 	"github.com/syncthing/syncthing/lib/fs"
-	"github.com/syncthing/syncthing/lib/util"
+	"github.com/syncthing/syncthing/lib/structutil"
 )
 
 // internalVersioningConfiguration is used in XML serialization
@@ -39,7 +39,7 @@ func (c VersioningConfiguration) Copy() VersioningConfiguration {
 }
 
 func (c *VersioningConfiguration) UnmarshalJSON(data []byte) error {
-	util.SetDefaults(c)
+	structutil.SetDefaults(c)
 	type noCustomUnmarshal VersioningConfiguration
 	ptr := (*noCustomUnmarshal)(c)
 	return json.Unmarshal(data, ptr)
@@ -47,7 +47,7 @@ func (c *VersioningConfiguration) UnmarshalJSON(data []byte) error {
 
 func (c *VersioningConfiguration) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
 	var intCfg internalVersioningConfiguration
-	util.SetDefaults(&intCfg)
+	structutil.SetDefaults(&intCfg)
 	if err := d.DecodeElement(&intCfg, &start); err != nil {
 		return err
 	}
diff --git a/lib/connections/service.go b/lib/connections/service.go
index 55118f8fb..484fb94cc 100644
--- a/lib/connections/service.go
+++ b/lib/connections/service.go
@@ -23,6 +23,8 @@ import (
 	stdsync "sync"
 	"time"
 
+	"golang.org/x/exp/slices"
+
 	"github.com/syncthing/syncthing/lib/config"
 	"github.com/syncthing/syncthing/lib/connections/registry"
 	"github.com/syncthing/syncthing/lib/discover"
@@ -30,9 +32,10 @@ import (
 	"github.com/syncthing/syncthing/lib/nat"
 	"github.com/syncthing/syncthing/lib/osutil"
 	"github.com/syncthing/syncthing/lib/protocol"
+	"github.com/syncthing/syncthing/lib/semaphore"
+	"github.com/syncthing/syncthing/lib/stringutil"
 	"github.com/syncthing/syncthing/lib/svcutil"
 	"github.com/syncthing/syncthing/lib/sync"
-	"github.com/syncthing/syncthing/lib/util"
 
 	// Registers NAT service providers
 	_ "github.com/syncthing/syncthing/lib/pmp"
@@ -582,7 +585,7 @@ func (s *service) dialDevices(ctx context.Context, now time.Time, cfg config.Con
 	// allowed additional number of connections (if limited).
 	numConns := 0
 	var numConnsMut stdsync.Mutex
-	dialSemaphore := util.NewSemaphore(dialMaxParallel)
+	dialSemaphore := semaphore.New(dialMaxParallel)
 	dialWG := new(stdsync.WaitGroup)
 	dialCtx, dialCancel := context.WithCancel(ctx)
 	defer func() {
@@ -698,7 +701,7 @@ func (s *service) resolveDeviceAddrs(ctx context.Context, cfg config.DeviceConfi
 			addrs = append(addrs, addr)
 		}
 	}
-	return util.UniqueTrimmedStrings(addrs)
+	return stringutil.UniqueTrimmedStrings(addrs)
 }
 
 type lanChecker struct {
@@ -875,7 +878,7 @@ func (s *service) checkAndSignalConnectLoopOnUpdatedDevices(from, to config.Conf
 		if oldDev, ok := oldDevices[dev.DeviceID]; !ok || oldDev.Paused {
 			s.dialNowDevices[dev.DeviceID] = struct{}{}
 			dial = true
-		} else if !util.EqualStrings(oldDev.Addresses, dev.Addresses) {
+		} else if !slices.Equal(oldDev.Addresses, dev.Addresses) {
 			dial = true
 		}
 	}
@@ -905,7 +908,7 @@ func (s *service) AllAddresses() []string {
 		}
 	}
 	s.listenersMut.RUnlock()
-	return util.UniqueTrimmedStrings(addrs)
+	return stringutil.UniqueTrimmedStrings(addrs)
 }
 
 func (s *service) ExternalAddresses() []string {
@@ -920,7 +923,7 @@ func (s *service) ExternalAddresses() []string {
 		}
 	}
 	s.listenersMut.RUnlock()
-	return util.UniqueTrimmedStrings(addrs)
+	return stringutil.UniqueTrimmedStrings(addrs)
 }
 
 func (s *service) ListenerStatus() map[string]ListenerStatusEntry {
@@ -1079,7 +1082,7 @@ func IsAllowedNetwork(host string, allowed []string) bool {
 	return false
 }
 
-func (s *service) dialParallel(ctx context.Context, deviceID protocol.DeviceID, dialTargets []dialTarget, parentSema *util.Semaphore) (internalConn, bool) {
+func (s *service) dialParallel(ctx context.Context, deviceID protocol.DeviceID, dialTargets []dialTarget, parentSema *semaphore.Semaphore) (internalConn, bool) {
 	// Group targets into buckets by priority
 	dialTargetBuckets := make(map[int][]dialTarget, len(dialTargets))
 	for _, tgt := range dialTargets {
@@ -1095,7 +1098,7 @@ func (s *service) dialParallel(ctx context.Context, deviceID protocol.DeviceID,
 	// Sort the priorities so that we dial lowest first (which means highest...)
 	sort.Ints(priorities)
 
-	sema := util.MultiSemaphore{util.NewSemaphore(dialMaxParallelPerDevice), parentSema}
+	sema := semaphore.MultiSemaphore{semaphore.New(dialMaxParallelPerDevice), parentSema}
 	for _, prio := range priorities {
 		tgts := dialTargetBuckets[prio]
 		res := make(chan internalConn, len(tgts))
diff --git a/lib/db/lowlevel.go b/lib/db/lowlevel.go
index 88792a36d..86bbaa31f 100644
--- a/lib/db/lowlevel.go
+++ b/lib/db/lowlevel.go
@@ -23,9 +23,9 @@ import (
 	"github.com/syncthing/syncthing/lib/fs"
 	"github.com/syncthing/syncthing/lib/protocol"
 	"github.com/syncthing/syncthing/lib/sha256"
+	"github.com/syncthing/syncthing/lib/stringutil"
 	"github.com/syncthing/syncthing/lib/svcutil"
 	"github.com/syncthing/syncthing/lib/sync"
-	"github.com/syncthing/syncthing/lib/util"
 	"github.com/thejerf/suture/v4"
 )
 
@@ -1042,7 +1042,7 @@ func (db *Lowlevel) loadMetadataTracker(folder string) (*metadataTracker, error)
 	}
 
 	if age := time.Since(meta.Created()); age > db.recheckInterval {
-		l.Infof("Stored folder metadata for %q is %v old; recalculating", folder, util.NiceDurationString(age))
+		l.Infof("Stored folder metadata for %q is %v old; recalculating", folder, stringutil.NiceDurationString(age))
 		return db.getMetaAndCheck(folder)
 	}
 
diff --git a/lib/discover/manager.go b/lib/discover/manager.go
index efbdc05d2..4cec90dce 100644
--- a/lib/discover/manager.go
+++ b/lib/discover/manager.go
@@ -22,9 +22,9 @@ import (
 	"github.com/syncthing/syncthing/lib/connections/registry"
 	"github.com/syncthing/syncthing/lib/events"
 	"github.com/syncthing/syncthing/lib/protocol"
+	"github.com/syncthing/syncthing/lib/stringutil"
 	"github.com/syncthing/syncthing/lib/svcutil"
 	"github.com/syncthing/syncthing/lib/sync"
-	"github.com/syncthing/syncthing/lib/util"
 )
 
 // The Manager aggregates results from multiple Finders. Each Finder has
@@ -158,7 +158,7 @@ func (m *manager) Lookup(ctx context.Context, deviceID protocol.DeviceID) (addre
 	}
 	m.mut.RUnlock()
 
-	addresses = util.UniqueTrimmedStrings(addresses)
+	addresses = stringutil.UniqueTrimmedStrings(addresses)
 	sort.Strings(addresses)
 
 	l.Debugln("lookup results for", deviceID)
@@ -223,7 +223,7 @@ func (m *manager) Cache() map[protocol.DeviceID]CacheEntry {
 	m.mut.RUnlock()
 
 	for k, v := range res {
-		v.Addresses = util.UniqueTrimmedStrings(v.Addresses)
+		v.Addresses = stringutil.UniqueTrimmedStrings(v.Addresses)
 		res[k] = v
 	}
 
diff --git a/lib/model/folder.go b/lib/model/folder.go
index b62281562..e69025d74 100644
--- a/lib/model/folder.go
+++ b/lib/model/folder.go
@@ -24,10 +24,11 @@ import (
 	"github.com/syncthing/syncthing/lib/osutil"
 	"github.com/syncthing/syncthing/lib/protocol"
 	"github.com/syncthing/syncthing/lib/scanner"
+	"github.com/syncthing/syncthing/lib/semaphore"
 	"github.com/syncthing/syncthing/lib/stats"
+	"github.com/syncthing/syncthing/lib/stringutil"
 	"github.com/syncthing/syncthing/lib/svcutil"
 	"github.com/syncthing/syncthing/lib/sync"
-	"github.com/syncthing/syncthing/lib/util"
 	"github.com/syncthing/syncthing/lib/versioner"
 	"github.com/syncthing/syncthing/lib/watchaggregator"
 )
@@ -39,7 +40,7 @@ type folder struct {
 	stateTracker
 	config.FolderConfiguration
 	*stats.FolderStatisticsReference
-	ioLimiter *util.Semaphore
+	ioLimiter *semaphore.Semaphore
 
 	localFlags uint32
 
@@ -95,7 +96,7 @@ type puller interface {
 	pull() (bool, error) // true when successful and should not be retried
 }
 
-func newFolder(model *model, fset *db.FileSet, ignores *ignore.Matcher, cfg config.FolderConfiguration, evLogger events.Logger, ioLimiter *util.Semaphore, ver versioner.Versioner) folder {
+func newFolder(model *model, fset *db.FileSet, ignores *ignore.Matcher, cfg config.FolderConfiguration, evLogger events.Logger, ioLimiter *semaphore.Semaphore, ver versioner.Versioner) folder {
 	f := folder{
 		stateTracker:              newStateTracker(cfg.ID, evLogger),
 		FolderConfiguration:       cfg,
@@ -426,7 +427,7 @@ func (f *folder) pull() (success bool, err error) {
 
 	// Pulling failed, try again later.
 	delay := f.pullPause + time.Since(startTime)
-	l.Infof("Folder %v isn't making sync progress - retrying in %v.", f.Description(), util.NiceDurationString(delay))
+	l.Infof("Folder %v isn't making sync progress - retrying in %v.", f.Description(), stringutil.NiceDurationString(delay))
 	f.pullFailTimer.Reset(delay)
 
 	return false, err
diff --git a/lib/model/folder_recvenc.go b/lib/model/folder_recvenc.go
index 7e2c5fda6..e10be6adf 100644
--- a/lib/model/folder_recvenc.go
+++ b/lib/model/folder_recvenc.go
@@ -16,7 +16,7 @@ import (
 	"github.com/syncthing/syncthing/lib/fs"
 	"github.com/syncthing/syncthing/lib/ignore"
 	"github.com/syncthing/syncthing/lib/protocol"
-	"github.com/syncthing/syncthing/lib/util"
+	"github.com/syncthing/syncthing/lib/semaphore"
 	"github.com/syncthing/syncthing/lib/versioner"
 )
 
@@ -28,7 +28,7 @@ type receiveEncryptedFolder struct {
 	*sendReceiveFolder
 }
 
-func newReceiveEncryptedFolder(model *model, fset *db.FileSet, ignores *ignore.Matcher, cfg config.FolderConfiguration, ver versioner.Versioner, evLogger events.Logger, ioLimiter *util.Semaphore) service {
+func newReceiveEncryptedFolder(model *model, fset *db.FileSet, ignores *ignore.Matcher, cfg config.FolderConfiguration, ver versioner.Versioner, evLogger events.Logger, ioLimiter *semaphore.Semaphore) service {
 	f := &receiveEncryptedFolder{newSendReceiveFolder(model, fset, ignores, cfg, ver, evLogger, ioLimiter).(*sendReceiveFolder)}
 	f.localFlags = protocol.FlagLocalReceiveOnly // gets propagated to the scanner, and set on locally changed files
 	return f
diff --git a/lib/model/folder_recvonly.go b/lib/model/folder_recvonly.go
index 21f927cd4..ec76704f3 100644
--- a/lib/model/folder_recvonly.go
+++ b/lib/model/folder_recvonly.go
@@ -15,7 +15,7 @@ import (
 	"github.com/syncthing/syncthing/lib/events"
 	"github.com/syncthing/syncthing/lib/ignore"
 	"github.com/syncthing/syncthing/lib/protocol"
-	"github.com/syncthing/syncthing/lib/util"
+	"github.com/syncthing/syncthing/lib/semaphore"
 	"github.com/syncthing/syncthing/lib/versioner"
 )
 
@@ -57,7 +57,7 @@ type receiveOnlyFolder struct {
 	*sendReceiveFolder
 }
 
-func newReceiveOnlyFolder(model *model, fset *db.FileSet, ignores *ignore.Matcher, cfg config.FolderConfiguration, ver versioner.Versioner, evLogger events.Logger, ioLimiter *util.Semaphore) service {
+func newReceiveOnlyFolder(model *model, fset *db.FileSet, ignores *ignore.Matcher, cfg config.FolderConfiguration, ver versioner.Versioner, evLogger events.Logger, ioLimiter *semaphore.Semaphore) service {
 	sr := newSendReceiveFolder(model, fset, ignores, cfg, ver, evLogger, ioLimiter).(*sendReceiveFolder)
 	sr.localFlags = protocol.FlagLocalReceiveOnly // gets propagated to the scanner, and set on locally changed files
 	return &receiveOnlyFolder{sr}
diff --git a/lib/model/folder_sendonly.go b/lib/model/folder_sendonly.go
index 0e23a9f55..f1e59c467 100644
--- a/lib/model/folder_sendonly.go
+++ b/lib/model/folder_sendonly.go
@@ -12,7 +12,7 @@ import (
 	"github.com/syncthing/syncthing/lib/events"
 	"github.com/syncthing/syncthing/lib/ignore"
 	"github.com/syncthing/syncthing/lib/protocol"
-	"github.com/syncthing/syncthing/lib/util"
+	"github.com/syncthing/syncthing/lib/semaphore"
 	"github.com/syncthing/syncthing/lib/versioner"
 )
 
@@ -24,7 +24,7 @@ type sendOnlyFolder struct {
 	folder
 }
 
-func newSendOnlyFolder(model *model, fset *db.FileSet, ignores *ignore.Matcher, cfg config.FolderConfiguration, _ versioner.Versioner, evLogger events.Logger, ioLimiter *util.Semaphore) service {
+func newSendOnlyFolder(model *model, fset *db.FileSet, ignores *ignore.Matcher, cfg config.FolderConfiguration, _ versioner.Versioner, evLogger events.Logger, ioLimiter *semaphore.Semaphore) service {
 	f := &sendOnlyFolder{
 		folder: newFolder(model, fset, ignores, cfg, evLogger, ioLimiter, nil),
 	}
diff --git a/lib/model/folder_sendrecv.go b/lib/model/folder_sendrecv.go
index bdc10fecf..5be363000 100644
--- a/lib/model/folder_sendrecv.go
+++ b/lib/model/folder_sendrecv.go
@@ -27,9 +27,9 @@ import (
 	"github.com/syncthing/syncthing/lib/osutil"
 	"github.com/syncthing/syncthing/lib/protocol"
 	"github.com/syncthing/syncthing/lib/scanner"
+	"github.com/syncthing/syncthing/lib/semaphore"
 	"github.com/syncthing/syncthing/lib/sha256"
 	"github.com/syncthing/syncthing/lib/sync"
-	"github.com/syncthing/syncthing/lib/util"
 	"github.com/syncthing/syncthing/lib/versioner"
 	"github.com/syncthing/syncthing/lib/weakhash"
 )
@@ -125,17 +125,17 @@ type sendReceiveFolder struct {
 
 	queue              *jobQueue
 	blockPullReorderer blockPullReorderer
-	writeLimiter       *util.Semaphore
+	writeLimiter       *semaphore.Semaphore
 
 	tempPullErrors map[string]string // pull errors that might be just transient
 }
 
-func newSendReceiveFolder(model *model, fset *db.FileSet, ignores *ignore.Matcher, cfg config.FolderConfiguration, ver versioner.Versioner, evLogger events.Logger, ioLimiter *util.Semaphore) service {
+func newSendReceiveFolder(model *model, fset *db.FileSet, ignores *ignore.Matcher, cfg config.FolderConfiguration, ver versioner.Versioner, evLogger events.Logger, ioLimiter *semaphore.Semaphore) service {
 	f := &sendReceiveFolder{
 		folder:             newFolder(model, fset, ignores, cfg, evLogger, ioLimiter, ver),
 		queue:              newJobQueue(),
 		blockPullReorderer: newBlockPullReorderer(cfg.BlockPullOrder, model.id, cfg.DeviceIDs()),
-		writeLimiter:       util.NewSemaphore(cfg.MaxConcurrentWrites),
+		writeLimiter:       semaphore.New(cfg.MaxConcurrentWrites),
 	}
 	f.folder.puller = f
 
@@ -1492,7 +1492,7 @@ func (*sendReceiveFolder) verifyBuffer(buf []byte, block protocol.BlockInfo) err
 }
 
 func (f *sendReceiveFolder) pullerRoutine(snap *db.Snapshot, in <-chan pullBlockState, out chan<- *sharedPullerState) {
-	requestLimiter := util.NewSemaphore(f.PullerMaxPendingKiB * 1024)
+	requestLimiter := semaphore.New(f.PullerMaxPendingKiB * 1024)
 	wg := sync.NewWaitGroup()
 
 	for state := range in {
diff --git a/lib/model/model.go b/lib/model/model.go
index 0fafd0d03..2ab5e8b22 100644
--- a/lib/model/model.go
+++ b/lib/model/model.go
@@ -38,11 +38,11 @@ import (
 	"github.com/syncthing/syncthing/lib/osutil"
 	"github.com/syncthing/syncthing/lib/protocol"
 	"github.com/syncthing/syncthing/lib/scanner"
+	"github.com/syncthing/syncthing/lib/semaphore"
 	"github.com/syncthing/syncthing/lib/stats"
 	"github.com/syncthing/syncthing/lib/svcutil"
 	"github.com/syncthing/syncthing/lib/sync"
 	"github.com/syncthing/syncthing/lib/ur/contract"
-	"github.com/syncthing/syncthing/lib/util"
 	"github.com/syncthing/syncthing/lib/versioner"
 )
 
@@ -136,10 +136,10 @@ type model struct {
 	shortID         protocol.ShortID
 	// globalRequestLimiter limits the amount of data in concurrent incoming
 	// requests
-	globalRequestLimiter *util.Semaphore
+	globalRequestLimiter *semaphore.Semaphore
 	// folderIOLimiter limits the number of concurrent I/O heavy operations,
 	// such as scans and pulls.
-	folderIOLimiter *util.Semaphore
+	folderIOLimiter *semaphore.Semaphore
 	fatalChan       chan error
 	started         chan struct{}
 	keyGen          *protocol.KeyGenerator
@@ -160,7 +160,7 @@ type model struct {
 	// fields protected by pmut
 	pmut                sync.RWMutex
 	conn                map[protocol.DeviceID]protocol.Connection
-	connRequestLimiters map[protocol.DeviceID]*util.Semaphore
+	connRequestLimiters map[protocol.DeviceID]*semaphore.Semaphore
 	closed              map[protocol.DeviceID]chan struct{}
 	helloMessages       map[protocol.DeviceID]protocol.Hello
 	deviceDownloads     map[protocol.DeviceID]*deviceDownloadState
@@ -173,7 +173,7 @@ type model struct {
 
 var _ config.Verifier = &model{}
 
-type folderFactory func(*model, *db.FileSet, *ignore.Matcher, config.FolderConfiguration, versioner.Versioner, events.Logger, *util.Semaphore) service
+type folderFactory func(*model, *db.FileSet, *ignore.Matcher, config.FolderConfiguration, versioner.Versioner, events.Logger, *semaphore.Semaphore) service
 
 var folderFactories = make(map[config.FolderType]folderFactory)
 
@@ -222,8 +222,8 @@ func NewModel(cfg config.Wrapper, id protocol.DeviceID, clientName, clientVersio
 		finder:               db.NewBlockFinder(ldb),
 		progressEmitter:      NewProgressEmitter(cfg, evLogger),
 		shortID:              id.Short(),
-		globalRequestLimiter: util.NewSemaphore(1024 * cfg.Options().MaxConcurrentIncomingRequestKiB()),
-		folderIOLimiter:      util.NewSemaphore(cfg.Options().MaxFolderConcurrency()),
+		globalRequestLimiter: semaphore.New(1024 * cfg.Options().MaxConcurrentIncomingRequestKiB()),
+		folderIOLimiter:      semaphore.New(cfg.Options().MaxFolderConcurrency()),
 		fatalChan:            make(chan error),
 		started:              make(chan struct{}),
 		keyGen:               keyGen,
@@ -243,7 +243,7 @@ func NewModel(cfg config.Wrapper, id protocol.DeviceID, clientName, clientVersio
 		// fields protected by pmut
 		pmut:                sync.NewRWMutex(),
 		conn:                make(map[protocol.DeviceID]protocol.Connection),
-		connRequestLimiters: make(map[protocol.DeviceID]*util.Semaphore),
+		connRequestLimiters: make(map[protocol.DeviceID]*semaphore.Semaphore),
 		closed:              make(map[protocol.DeviceID]chan struct{}),
 		helloMessages:       make(map[protocol.DeviceID]protocol.Hello),
 		deviceDownloads:     make(map[protocol.DeviceID]*deviceDownloadState),
@@ -1966,8 +1966,8 @@ func (m *model) Request(conn protocol.Connection, folder, name string, _, size i
 // skipping nil limiters, then returns a requestResponse of the given size.
 // When the requestResponse is closed the limiters are given back the bytes,
 // in reverse order.
-func newLimitedRequestResponse(size int, limiters ...*util.Semaphore) *requestResponse {
-	multi := util.MultiSemaphore(limiters)
+func newLimitedRequestResponse(size int, limiters ...*semaphore.Semaphore) *requestResponse {
+	multi := semaphore.MultiSemaphore(limiters)
 	multi.Take(size)
 
 	res := newRequestResponse(size)
@@ -2261,9 +2261,9 @@ func (m *model) AddConnection(conn protocol.Connection, hello protocol.Hello) {
 	// 0: default, <0: no limiting
 	switch {
 	case device.MaxRequestKiB > 0:
-		m.connRequestLimiters[deviceID] = util.NewSemaphore(1024 * device.MaxRequestKiB)
+		m.connRequestLimiters[deviceID] = semaphore.New(1024 * device.MaxRequestKiB)
 	case device.MaxRequestKiB == 0:
-		m.connRequestLimiters[deviceID] = util.NewSemaphore(1024 * defaultPullerPendingKiB)
+		m.connRequestLimiters[deviceID] = semaphore.New(1024 * defaultPullerPendingKiB)
 	}
 
 	m.helloMessages[deviceID] = hello
diff --git a/lib/model/model_test.go b/lib/model/model_test.go
index daaa76fde..878239eaa 100644
--- a/lib/model/model_test.go
+++ b/lib/model/model_test.go
@@ -35,8 +35,8 @@ import (
 	"github.com/syncthing/syncthing/lib/protocol"
 	protocolmocks "github.com/syncthing/syncthing/lib/protocol/mocks"
 	srand "github.com/syncthing/syncthing/lib/rand"
-	"github.com/syncthing/syncthing/lib/testutils"
-	"github.com/syncthing/syncthing/lib/util"
+	"github.com/syncthing/syncthing/lib/semaphore"
+	"github.com/syncthing/syncthing/lib/testutil"
 	"github.com/syncthing/syncthing/lib/versioner"
 )
 
@@ -2968,10 +2968,10 @@ func TestConnCloseOnRestart(t *testing.T) {
 	m := setupModel(t, w)
 	defer cleanupModelAndRemoveDir(m, fcfg.Filesystem(nil).URI())
 
-	br := &testutils.BlockingRW{}
-	nw := &testutils.NoopRW{}
+	br := &testutil.BlockingRW{}
+	nw := &testutil.NoopRW{}
 	ci := &protocolmocks.ConnectionInfo{}
-	m.AddConnection(protocol.NewConnection(device1, br, nw, testutils.NoopCloser{}, m, ci, protocol.CompressionNever, nil, m.keyGen), protocol.Hello{})
+	m.AddConnection(protocol.NewConnection(device1, br, nw, testutil.NoopCloser{}, m, ci, protocol.CompressionNever, nil, m.keyGen), protocol.Hello{})
 	m.pmut.RLock()
 	if len(m.closed) != 1 {
 		t.Fatalf("Expected just one conn (len(m.closed) == %v)", len(m.closed))
@@ -3113,9 +3113,9 @@ func TestDeviceWasSeen(t *testing.T) {
 }
 
 func TestNewLimitedRequestResponse(t *testing.T) {
-	l0 := util.NewSemaphore(0)
-	l1 := util.NewSemaphore(1024)
-	l2 := (*util.Semaphore)(nil)
+	l0 := semaphore.New(0)
+	l1 := semaphore.New(1024)
+	l2 := (*semaphore.Semaphore)(nil)
 
 	// Should take 500 bytes from any non-unlimited non-nil limiters.
 	res := newLimitedRequestResponse(500, l0, l1, l2)
diff --git a/lib/model/queue_test.go b/lib/model/queue_test.go
index 9f49a683b..34ff67fd8 100644
--- a/lib/model/queue_test.go
+++ b/lib/model/queue_test.go
@@ -13,6 +13,7 @@ import (
 	"time"
 
 	"github.com/d4l3k/messagediff"
+	"golang.org/x/exp/slices"
 )
 
 func TestJobQueue(t *testing.T) {
@@ -282,7 +283,6 @@ func BenchmarkJobQueuePushPopDone10k(b *testing.B) {
 			q.Done(n)
 		}
 	}
-
 }
 
 func TestQueuePagination(t *testing.T) {
@@ -302,21 +302,21 @@ func TestQueuePagination(t *testing.T) {
 	progress, queued, skip = q.Jobs(1, 5)
 	if len(progress) != 0 || len(queued) != 5 || skip != 0 {
 		t.Error("Wrong length", len(progress), len(queued), 0)
-	} else if !equalStrings(queued, names[:5]) {
+	} else if !slices.Equal(queued, names[:5]) {
 		t.Errorf("Wrong elements in queued, got %v, expected %v", queued, names[:5])
 	}
 
 	progress, queued, skip = q.Jobs(2, 5)
 	if len(progress) != 0 || len(queued) != 5 || skip != 5 {
 		t.Error("Wrong length", len(progress), len(queued), 0)
-	} else if !equalStrings(queued, names[5:]) {
+	} else if !slices.Equal(queued, names[5:]) {
 		t.Errorf("Wrong elements in queued, got %v, expected %v", queued, names[5:])
 	}
 
 	progress, queued, skip = q.Jobs(2, 7)
 	if len(progress) != 0 || len(queued) != 3 || skip != 7 {
 		t.Error("Wrong length", len(progress), len(queued), 0)
-	} else if !equalStrings(queued, names[7:]) {
+	} else if !slices.Equal(queued, names[7:]) {
 		t.Errorf("Wrong elements in queued, got %v, expected %v", queued, names[7:])
 	}
 
@@ -338,23 +338,23 @@ func TestQueuePagination(t *testing.T) {
 	progress, queued, skip = q.Jobs(1, 5)
 	if len(progress) != 1 || len(queued) != 4 || skip != 0 {
 		t.Error("Wrong length", len(progress), len(queued), 0)
-	} else if !equalStrings(progress, names[:1]) {
+	} else if !slices.Equal(progress, names[:1]) {
 		t.Errorf("Wrong elements in progress, got %v, expected %v", progress, names[:1])
-	} else if !equalStrings(queued, names[1:5]) {
+	} else if !slices.Equal(queued, names[1:5]) {
 		t.Errorf("Wrong elements in queued, got %v, expected %v", queued, names[1:5])
 	}
 
 	progress, queued, skip = q.Jobs(2, 5)
 	if len(progress) != 0 || len(queued) != 5 || skip != 5 {
 		t.Error("Wrong length", len(progress), len(queued), 0)
-	} else if !equalStrings(queued, names[5:]) {
+	} else if !slices.Equal(queued, names[5:]) {
 		t.Errorf("Wrong elements in queued, got %v, expected %v", queued, names[5:])
 	}
 
 	progress, queued, skip = q.Jobs(2, 7)
 	if len(progress) != 0 || len(queued) != 3 || skip != 7 {
 		t.Error("Wrong length", len(progress), len(queued), 0)
-	} else if !equalStrings(queued, names[7:]) {
+	} else if !slices.Equal(queued, names[7:]) {
 		t.Errorf("Wrong elements in queued, got %v, expected %v", queued, names[7:])
 	}
 
@@ -378,25 +378,25 @@ func TestQueuePagination(t *testing.T) {
 	progress, queued, skip = q.Jobs(1, 5)
 	if len(progress) != 5 || len(queued) != 0 || skip != 0 {
 		t.Error("Wrong length", len(progress), len(queued), 0)
-	} else if !equalStrings(progress, names[:5]) {
+	} else if !slices.Equal(progress, names[:5]) {
 		t.Errorf("Wrong elements in progress, got %v, expected %v", progress, names[:5])
 	}
 
 	progress, queued, skip = q.Jobs(2, 5)
 	if len(progress) != 3 || len(queued) != 2 || skip != 5 {
 		t.Error("Wrong length", len(progress), len(queued), 0)
-	} else if !equalStrings(progress, names[5:8]) {
+	} else if !slices.Equal(progress, names[5:8]) {
 		t.Errorf("Wrong elements in progress, got %v, expected %v", progress, names[5:8])
-	} else if !equalStrings(queued, names[8:]) {
+	} else if !slices.Equal(queued, names[8:]) {
 		t.Errorf("Wrong elements in queued, got %v, expected %v", queued, names[8:])
 	}
 
 	progress, queued, skip = q.Jobs(2, 7)
 	if len(progress) != 1 || len(queued) != 2 || skip != 7 {
 		t.Error("Wrong length", len(progress), len(queued), 0)
-	} else if !equalStrings(progress, names[7:8]) {
+	} else if !slices.Equal(progress, names[7:8]) {
 		t.Errorf("Wrong elements in progress, got %v, expected %v", progress, names[7:8])
-	} else if !equalStrings(queued, names[8:]) {
+	} else if !slices.Equal(queued, names[8:]) {
 		t.Errorf("Wrong elements in queued, got %v, expected %v", queued, names[8:])
 	}
 
@@ -405,15 +405,3 @@ func TestQueuePagination(t *testing.T) {
 		t.Error("Wrong length", len(progress), len(queued), 0)
 	}
 }
-
-func equalStrings(first, second []string) bool {
-	if len(first) != len(second) {
-		return false
-	}
-	for i := range first {
-		if first[i] != second[i] {
-			return false
-		}
-	}
-	return true
-}
diff --git a/lib/netutil/netutil.go b/lib/netutil/netutil.go
new file mode 100644
index 000000000..d1b4a7f5b
--- /dev/null
+++ b/lib/netutil/netutil.go
@@ -0,0 +1,18 @@
+// Copyright (C) 2023 The Syncthing Authors.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+package netutil
+
+import "net/url"
+
+// Address constructs a URL from the given network and hostname.
+func AddressURL(network, host string) string {
+	u := url.URL{
+		Scheme: network,
+		Host:   host,
+	}
+	return u.String()
+}
diff --git a/lib/netutil/netutil_test.go b/lib/netutil/netutil_test.go
new file mode 100644
index 000000000..ccaebca09
--- /dev/null
+++ b/lib/netutil/netutil_test.go
@@ -0,0 +1,28 @@
+// Copyright (C) 2023 The Syncthing Authors.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+package netutil
+
+import "testing"
+
+func TestAddress(t *testing.T) {
+	tests := []struct {
+		network string
+		host    string
+		result  string
+	}{
+		{"tcp", "google.com", "tcp://google.com"},
+		{"foo", "google", "foo://google"},
+		{"123", "456", "123://456"},
+	}
+
+	for _, test := range tests {
+		result := AddressURL(test.network, test.host)
+		if result != test.result {
+			t.Errorf("%s != %s", result, test.result)
+		}
+	}
+}
diff --git a/lib/pmp/pmp.go b/lib/pmp/pmp.go
index ac8823e7a..fe711b702 100644
--- a/lib/pmp/pmp.go
+++ b/lib/pmp/pmp.go
@@ -19,7 +19,7 @@ import (
 
 	"github.com/syncthing/syncthing/lib/nat"
 	"github.com/syncthing/syncthing/lib/osutil"
-	"github.com/syncthing/syncthing/lib/util"
+	"github.com/syncthing/syncthing/lib/svcutil"
 )
 
 func init() {
@@ -28,7 +28,7 @@ func init() {
 
 func Discover(ctx context.Context, renewal, timeout time.Duration) []nat.Device {
 	var ip net.IP
-	err := util.CallWithContext(ctx, func() error {
+	err := svcutil.CallWithContext(ctx, func() error {
 		var err error
 		ip, err = gateway.DiscoverGateway()
 		return err
@@ -46,7 +46,7 @@ func Discover(ctx context.Context, renewal, timeout time.Duration) []nat.Device
 	c := natpmp.NewClientWithTimeout(ip, timeout)
 	// Try contacting the gateway, if it does not respond, assume it does not
 	// speak NAT-PMP.
-	err = util.CallWithContext(ctx, func() error {
+	err = svcutil.CallWithContext(ctx, func() error {
 		_, ierr := c.GetExternalAddress()
 		return ierr
 	})
@@ -104,7 +104,7 @@ func (w *wrapper) AddPortMapping(ctx context.Context, protocol nat.Protocol, int
 		duration = w.renewal
 	}
 	var result *natpmp.AddPortMappingResult
-	err := util.CallWithContext(ctx, func() error {
+	err := svcutil.CallWithContext(ctx, func() error {
 		var err error
 		result, err = w.client.AddPortMapping(strings.ToLower(string(protocol)), internalPort, externalPort, int(duration/time.Second))
 		return err
@@ -118,7 +118,7 @@ func (w *wrapper) AddPortMapping(ctx context.Context, protocol nat.Protocol, int
 
 func (w *wrapper) GetExternalIPAddress(ctx context.Context) (net.IP, error) {
 	var result *natpmp.GetExternalAddressResult
-	err := util.CallWithContext(ctx, func() error {
+	err := svcutil.CallWithContext(ctx, func() error {
 		var err error
 		result, err = w.client.GetExternalAddress()
 		return err
diff --git a/lib/protocol/benchmark_test.go b/lib/protocol/benchmark_test.go
index 4fd07c407..588dee613 100644
--- a/lib/protocol/benchmark_test.go
+++ b/lib/protocol/benchmark_test.go
@@ -10,7 +10,7 @@ import (
 	"testing"
 
 	"github.com/syncthing/syncthing/lib/dialer"
-	"github.com/syncthing/syncthing/lib/testutils"
+	"github.com/syncthing/syncthing/lib/testutil"
 )
 
 func BenchmarkRequestsRawTCP(b *testing.B) {
@@ -60,9 +60,9 @@ func benchmarkRequestsTLS(b *testing.B, conn0, conn1 net.Conn) {
 
 func benchmarkRequestsConnPair(b *testing.B, conn0, conn1 net.Conn) {
 	// Start up Connections on them
-	c0 := NewConnection(LocalDeviceID, conn0, conn0, testutils.NoopCloser{}, new(fakeModel), new(mockedConnectionInfo), CompressionMetadata, nil, testKeyGen)
+	c0 := NewConnection(LocalDeviceID, conn0, conn0, testutil.NoopCloser{}, new(fakeModel), new(mockedConnectionInfo), CompressionMetadata, nil, testKeyGen)
 	c0.Start()
-	c1 := NewConnection(LocalDeviceID, conn1, conn1, testutils.NoopCloser{}, new(fakeModel), new(mockedConnectionInfo), CompressionMetadata, nil, testKeyGen)
+	c1 := NewConnection(LocalDeviceID, conn1, conn1, testutil.NoopCloser{}, new(fakeModel), new(mockedConnectionInfo), CompressionMetadata, nil, testKeyGen)
 	c1.Start()
 
 	// Satisfy the assertions in the protocol by sending an initial cluster config
diff --git a/lib/protocol/protocol_test.go b/lib/protocol/protocol_test.go
index 69f954aa3..fa751c1f7 100644
--- a/lib/protocol/protocol_test.go
+++ b/lib/protocol/protocol_test.go
@@ -19,7 +19,7 @@ import (
 	lz4 "github.com/pierrec/lz4/v4"
 	"github.com/syncthing/syncthing/lib/build"
 	"github.com/syncthing/syncthing/lib/rand"
-	"github.com/syncthing/syncthing/lib/testutils"
+	"github.com/syncthing/syncthing/lib/testutil"
 )
 
 var (
@@ -32,10 +32,10 @@ func TestPing(t *testing.T) {
 	ar, aw := io.Pipe()
 	br, bw := io.Pipe()
 
-	c0 := getRawConnection(NewConnection(c0ID, ar, bw, testutils.NoopCloser{}, newTestModel(), new(mockedConnectionInfo), CompressionAlways, nil, testKeyGen))
+	c0 := getRawConnection(NewConnection(c0ID, ar, bw, testutil.NoopCloser{}, newTestModel(), new(mockedConnectionInfo), CompressionAlways, nil, testKeyGen))
 	c0.Start()
 	defer closeAndWait(c0, ar, bw)
-	c1 := getRawConnection(NewConnection(c1ID, br, aw, testutils.NoopCloser{}, newTestModel(), new(mockedConnectionInfo), CompressionAlways, nil, testKeyGen))
+	c1 := getRawConnection(NewConnection(c1ID, br, aw, testutil.NoopCloser{}, newTestModel(), new(mockedConnectionInfo), CompressionAlways, nil, testKeyGen))
 	c1.Start()
 	defer closeAndWait(c1, ar, bw)
 	c0.ClusterConfig(ClusterConfig{})
@@ -58,10 +58,10 @@ func TestClose(t *testing.T) {
 	ar, aw := io.Pipe()
 	br, bw := io.Pipe()
 
-	c0 := getRawConnection(NewConnection(c0ID, ar, bw, testutils.NoopCloser{}, m0, new(mockedConnectionInfo), CompressionAlways, nil, testKeyGen))
+	c0 := getRawConnection(NewConnection(c0ID, ar, bw, testutil.NoopCloser{}, m0, new(mockedConnectionInfo), CompressionAlways, nil, testKeyGen))
 	c0.Start()
 	defer closeAndWait(c0, ar, bw)
-	c1 := NewConnection(c1ID, br, aw, testutils.NoopCloser{}, m1, new(mockedConnectionInfo), CompressionAlways, nil, testKeyGen)
+	c1 := NewConnection(c1ID, br, aw, testutil.NoopCloser{}, m1, new(mockedConnectionInfo), CompressionAlways, nil, testKeyGen)
 	c1.Start()
 	defer closeAndWait(c1, ar, bw)
 	c0.ClusterConfig(ClusterConfig{})
@@ -102,8 +102,8 @@ func TestCloseOnBlockingSend(t *testing.T) {
 
 	m := newTestModel()
 
-	rw := testutils.NewBlockingRW()
-	c := getRawConnection(NewConnection(c0ID, rw, rw, testutils.NoopCloser{}, m, new(mockedConnectionInfo), CompressionAlways, nil, testKeyGen))
+	rw := testutil.NewBlockingRW()
+	c := getRawConnection(NewConnection(c0ID, rw, rw, testutil.NoopCloser{}, m, new(mockedConnectionInfo), CompressionAlways, nil, testKeyGen))
 	c.Start()
 	defer closeAndWait(c, rw)
 
@@ -154,10 +154,10 @@ func TestCloseRace(t *testing.T) {
 	ar, aw := io.Pipe()
 	br, bw := io.Pipe()
 
-	c0 := getRawConnection(NewConnection(c0ID, ar, bw, testutils.NoopCloser{}, m0, new(mockedConnectionInfo), CompressionNever, nil, testKeyGen))
+	c0 := getRawConnection(NewConnection(c0ID, ar, bw, testutil.NoopCloser{}, m0, new(mockedConnectionInfo), CompressionNever, nil, testKeyGen))
 	c0.Start()
 	defer closeAndWait(c0, ar, bw)
-	c1 := NewConnection(c1ID, br, aw, testutils.NoopCloser{}, m1, new(mockedConnectionInfo), CompressionNever, nil, testKeyGen)
+	c1 := NewConnection(c1ID, br, aw, testutil.NoopCloser{}, m1, new(mockedConnectionInfo), CompressionNever, nil, testKeyGen)
 	c1.Start()
 	defer closeAndWait(c1, ar, bw)
 	c0.ClusterConfig(ClusterConfig{})
@@ -193,8 +193,8 @@ func TestCloseRace(t *testing.T) {
 func TestClusterConfigFirst(t *testing.T) {
 	m := newTestModel()
 
-	rw := testutils.NewBlockingRW()
-	c := getRawConnection(NewConnection(c0ID, rw, &testutils.NoopRW{}, testutils.NoopCloser{}, m, new(mockedConnectionInfo), CompressionAlways, nil, testKeyGen))
+	rw := testutil.NewBlockingRW()
+	c := getRawConnection(NewConnection(c0ID, rw, &testutil.NoopRW{}, testutil.NoopCloser{}, m, new(mockedConnectionInfo), CompressionAlways, nil, testKeyGen))
 	c.Start()
 	defer closeAndWait(c, rw)
 
@@ -245,8 +245,8 @@ func TestCloseTimeout(t *testing.T) {
 
 	m := newTestModel()
 
-	rw := testutils.NewBlockingRW()
-	c := getRawConnection(NewConnection(c0ID, rw, rw, testutils.NoopCloser{}, m, new(mockedConnectionInfo), CompressionAlways, nil, testKeyGen))
+	rw := testutil.NewBlockingRW()
+	c := getRawConnection(NewConnection(c0ID, rw, rw, testutil.NoopCloser{}, m, new(mockedConnectionInfo), CompressionAlways, nil, testKeyGen))
 	c.Start()
 	defer closeAndWait(c, rw)
 
@@ -898,8 +898,8 @@ func TestSha256OfEmptyBlock(t *testing.T) {
 func TestClusterConfigAfterClose(t *testing.T) {
 	m := newTestModel()
 
-	rw := testutils.NewBlockingRW()
-	c := getRawConnection(NewConnection(c0ID, rw, rw, testutils.NoopCloser{}, m, new(mockedConnectionInfo), CompressionAlways, nil, testKeyGen))
+	rw := testutil.NewBlockingRW()
+	c := getRawConnection(NewConnection(c0ID, rw, rw, testutil.NoopCloser{}, m, new(mockedConnectionInfo), CompressionAlways, nil, testKeyGen))
 	c.Start()
 	defer closeAndWait(c, rw)
 
@@ -922,8 +922,8 @@ func TestDispatcherToCloseDeadlock(t *testing.T) {
 	// Verify that we don't deadlock when calling Close() from within one of
 	// the model callbacks (ClusterConfig).
 	m := newTestModel()
-	rw := testutils.NewBlockingRW()
-	c := getRawConnection(NewConnection(c0ID, rw, &testutils.NoopRW{}, testutils.NoopCloser{}, m, new(mockedConnectionInfo), CompressionAlways, nil, testKeyGen))
+	rw := testutil.NewBlockingRW()
+	c := getRawConnection(NewConnection(c0ID, rw, &testutil.NoopRW{}, testutil.NoopCloser{}, m, new(mockedConnectionInfo), CompressionAlways, nil, testKeyGen))
 	m.ccFn = func(ClusterConfig) {
 		c.Close(errManual)
 	}
diff --git a/lib/util/semaphore.go b/lib/semaphore/semaphore.go
index 276234ed7..63bd6d277 100644
--- a/lib/util/semaphore.go
+++ b/lib/semaphore/semaphore.go
@@ -4,7 +4,7 @@
 // License, v. 2.0. If a copy of the MPL was not distributed with this file,
 // You can obtain one at https://mozilla.org/MPL/2.0/.
 
-package util
+package semaphore
 
 import (
 	"context"
@@ -18,7 +18,7 @@ type Semaphore struct {
 	cond      *sync.Cond
 }
 
-func NewSemaphore(max int) *Semaphore {
+func New(max int) *Semaphore {
 	if max < 0 {
 		max = 0
 	}
diff --git a/lib/util/semaphore_test.go b/lib/semaphore/semaphore_test.go
index dd1e56f4a..7ec047e36 100644
--- a/lib/util/semaphore_test.go
+++ b/lib/semaphore/semaphore_test.go
@@ -4,14 +4,16 @@
 // License, v. 2.0. If a copy of the MPL was not distributed with this file,
 // You can obtain one at https://mozilla.org/MPL/2.0/.
 
-package util
+package semaphore
 
 import "testing"
 
-func TestZeroByteSemaphore(_ *testing.T) {
+func TestZeroByteSemaphore(t *testing.T) {
+	t.Parallel()
+
 	// A semaphore with zero capacity is just a no-op.
 
-	s := NewSemaphore(0)
+	s := New(0)
 
 	// None of these should block or panic
 	s.Take(123)
@@ -20,9 +22,11 @@ func TestZeroByteSemaphore(_ *testing.T) {
 }
 
 func TestByteSemaphoreCapChangeUp(t *testing.T) {
+	t.Parallel()
+
 	// Waiting takes should unblock when the capacity increases
 
-	s := NewSemaphore(100)
+	s := New(100)
 
 	s.Take(75)
 	if s.available != 25 {
@@ -43,9 +47,11 @@ func TestByteSemaphoreCapChangeUp(t *testing.T) {
 }
 
 func TestByteSemaphoreCapChangeDown1(t *testing.T) {
+	t.Parallel()
+
 	// Things should make sense when capacity is adjusted down
 
-	s := NewSemaphore(100)
+	s := New(100)
 
 	s.Take(75)
 	if s.available != 25 {
@@ -64,9 +70,11 @@ func TestByteSemaphoreCapChangeDown1(t *testing.T) {
 }
 
 func TestByteSemaphoreCapChangeDown2(t *testing.T) {
+	t.Parallel()
+
 	// Things should make sense when capacity is adjusted down, different case
 
-	s := NewSemaphore(100)
+	s := New(100)
 
 	s.Take(75)
 	if s.available != 25 {
@@ -85,9 +93,11 @@ func TestByteSemaphoreCapChangeDown2(t *testing.T) {
 }
 
 func TestByteSemaphoreGiveMore(t *testing.T) {
+	t.Parallel()
+
 	// We shouldn't end up with more available than we have capacity...
 
-	s := NewSemaphore(100)
+	s := New(100)
 
 	s.Take(150)
 	if s.available != 0 {
diff --git a/lib/stringutil/stringutil.go b/lib/stringutil/stringutil.go
new file mode 100644
index 000000000..fdcab2768
--- /dev/null
+++ b/lib/stringutil/stringutil.go
@@ -0,0 +1,46 @@
+// Copyright (C) 2016 The Syncthing Authors.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+package stringutil
+
+import (
+	"strings"
+	"time"
+)
+
+// UniqueTrimmedStrings returns a list of all unique strings in ss,
+// in the order in which they first appear in ss, after trimming away
+// leading and trailing spaces.
+func UniqueTrimmedStrings(ss []string) []string {
+	m := make(map[string]struct{}, len(ss))
+	us := make([]string, 0, len(ss))
+	for _, v := range ss {
+		v = strings.Trim(v, " ")
+		if _, ok := m[v]; ok {
+			continue
+		}
+		m[v] = struct{}{}
+		us = append(us, v)
+	}
+
+	return us
+}
+
+func NiceDurationString(d time.Duration) string {
+	switch {
+	case d > 24*time.Hour:
+		d = d.Round(time.Hour)
+	case d > time.Hour:
+		d = d.Round(time.Minute)
+	case d > time.Minute:
+		d = d.Round(time.Second)
+	case d > time.Second:
+		d = d.Round(time.Millisecond)
+	case d > time.Millisecond:
+		d = d.Round(time.Microsecond)
+	}
+	return d.String()
+}
diff --git a/lib/stringutil/stringutil_test.go b/lib/stringutil/stringutil_test.go
new file mode 100644
index 000000000..3ccac2281
--- /dev/null
+++ b/lib/stringutil/stringutil_test.go
@@ -0,0 +1,51 @@
+// Copyright (C) 2016 The Syncthing Authors.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at https://mozilla.org/MPL/2.0/.
+
+package stringutil
+
+import (
+	"testing"
+)
+
+func TestUniqueStrings(t *testing.T) {
+	tests := []struct {
+		input    []string
+		expected []string
+	}{
+		{
+			[]string{"a", "b"},
+			[]string{"a", "b"},
+		},
+		{
+			[]string{"a", "a"},
+			[]string{"a"},
+		},
+		{
+			[]string{"a", "a", "a", "a"},
+			[]string{"a"},
+		},
+		{
+			nil,
+			nil,
+		},
+		{
+			[]string{"       a     ", "     a  ", "b        ", "    b"},
+			[]string{"a", "b"},
+		},
+	}
+
+	for _, test := range tests {
+		result := UniqueTrimmedStrings(test.input)
+		if len(result) != len(test.expected) {
+			t.Errorf("%s != %s", result, test.expected)
+		}
+		for i := range result {
+			if test.expected[i] != result[i] {
+				t.Errorf("%s != %s", result, test.expected)
+			}
+		}
+	}
+}
diff --git a/lib/util/utils.go b/lib/structutil/structutil.go
index 43fafde78..e60a440f2 100644
--- a/lib/util/utils.go
+++ b/lib/structutil/structutil.go
@@ -1,19 +1,15 @@
-// Copyright (C) 2016 The Syncthing Authors.
+// Copyright (C) 2023 The Syncthing Authors.
 //
 // This Source Code Form is subject to the terms of the Mozilla Public
 // License, v. 2.0. If a copy of the MPL was not distributed with this file,
 // You can obtain one at https://mozilla.org/MPL/2.0/.
 
-package util
+package structutil
 
 import (
-	"context"
-	"fmt"
-	"net/url"
 	"reflect"
 	"strconv"
 	"strings"
-	"time"
 )
 
 type defaultParser interface {
@@ -21,7 +17,7 @@ type defaultParser interface {
 }
 
 // SetDefaults sets default values on a struct, based on the default annotation.
-func SetDefaults(data interface{}) {
+func SetDefaults(data any) {
 	s := reflect.ValueOf(data).Elem()
 	t := s.Type()
 
@@ -86,63 +82,15 @@ func SetDefaults(data interface{}) {
 	}
 }
 
-// CopyMatchingTag copies fields tagged tag:"value" from "from" struct onto "to" struct.
-func CopyMatchingTag(from interface{}, to interface{}, tag string, shouldCopy func(value string) bool) {
-	fromStruct := reflect.ValueOf(from).Elem()
-	fromType := fromStruct.Type()
-
-	toStruct := reflect.ValueOf(to).Elem()
-	toType := toStruct.Type()
-
-	if fromType != toType {
-		panic(fmt.Sprintf("non equal types: %s != %s", fromType, toType))
-	}
-
-	for i := 0; i < toStruct.NumField(); i++ {
-		fromField := fromStruct.Field(i)
-		toField := toStruct.Field(i)
-
-		if !toField.CanSet() {
-			// Unexported fields
-			continue
-		}
-
-		structTag := toType.Field(i).Tag
-
-		v := structTag.Get(tag)
-		if shouldCopy(v) {
-			toField.Set(fromField)
-		}
-	}
-}
-
-// UniqueTrimmedStrings returns a list of all unique strings in ss,
-// in the order in which they first appear in ss, after trimming away
-// leading and trailing spaces.
-func UniqueTrimmedStrings(ss []string) []string {
-	var m = make(map[string]struct{}, len(ss))
-	var us = make([]string, 0, len(ss))
-	for _, v := range ss {
-		v = strings.Trim(v, " ")
-		if _, ok := m[v]; ok {
-			continue
-		}
-		m[v] = struct{}{}
-		us = append(us, v)
-	}
-
-	return us
-}
-
-func FillNilExceptDeprecated(data interface{}) {
+func FillNilExceptDeprecated(data any) {
 	fillNil(data, true)
 }
 
-func FillNil(data interface{}) {
+func FillNil(data any) {
 	fillNil(data, false)
 }
 
-func fillNil(data interface{}, skipDeprecated bool) {
+func fillNil(data any, skipDeprecated bool) {
 	s := reflect.ValueOf(data).Elem()
 	t := s.Type()
 	for i := 0; i < s.NumField(); i++ {
@@ -190,7 +138,7 @@ func fillNil(data interface{}, skipDeprecated bool) {
 }
 
 // FillNilSlices sets default value on slices that are still nil.
-func FillNilSlices(data interface{}) error {
+func FillNilSlices(data any) error {
 	s := reflect.ValueOf(data).Elem()
 	t := s.Type()
 
@@ -220,55 +168,3 @@ func FillNilSlices(data interface{}) error {
 	}
 	return nil
 }
-
-// Address constructs a URL from the given network and hostname.
-func Address(network, host string) string {
-	u := url.URL{
-		Scheme: network,
-		Host:   host,
-	}
-	return u.String()
-}
-
-func CallWithContext(ctx context.Context, fn func() error) error {
-	var err error
-	done := make(chan struct{})
-	go func() {
-		err = fn()
-		close(done)
-	}()
-	select {
-	case <-done:
-		return err
-	case <-ctx.Done():
-		return ctx.Err()
-	}
-}
-
-func NiceDurationString(d time.Duration) string {
-	switch {
-	case d > 24*time.Hour:
-		d = d.Round(time.Hour)
-	case d > time.Hour:
-		d = d.Round(time.Minute)
-	case d > time.Minute:
-		d = d.Round(time.Second)
-	case d > time.Second:
-		d = d.Round(time.Millisecond)
-	case d > time.Millisecond:
-		d = d.Round(time.Microsecond)
-	}
-	return d.String()
-}
-
-func EqualStrings(a, b []string) bool {
-	if len(a) != len(b) {
-		return false
-	}
-	for i := range a {
-		if a[i] != b[i] {
-			return false
-		}
-	}
-	return true
-}
diff --git a/lib/util/utils_test.go b/lib/structutil/structutil_test.go
index d16ef2f48..0ded3b40c 100644
--- a/lib/util/utils_test.go
+++ b/lib/structutil/structutil_test.go
@@ -4,7 +4,7 @@
 // License, v. 2.0. If a copy of the MPL was not distributed with this file,
 // You can obtain one at https://mozilla.org/MPL/2.0/.
 
-package util
+package structutil
 
 import (
 	"testing"
@@ -55,46 +55,6 @@ func TestSetDefaults(t *testing.T) {
 	}
 }
 
-func TestUniqueStrings(t *testing.T) {
-	tests := []struct {
-		input    []string
-		expected []string
-	}{
-		{
-			[]string{"a", "b"},
-			[]string{"a", "b"},
-		},
-		{
-			[]string{"a", "a"},
-			[]string{"a"},
-		},
-		{
-			[]string{"a", "a", "a", "a"},
-			[]string{"a"},
-		},
-		{
-			nil,
-			nil,
-		},
-		{
-			[]string{"       a     ", "     a  ", "b        ", "    b"},
-			[]string{"a", "b"},
-		},
-	}
-
-	for _, test := range tests {
-		result := UniqueTrimmedStrings(test.input)
-		if len(result) != len(test.expected) {
-			t.Errorf("%s != %s", result, test.expected)
-		}
-		for i := range result {
-			if test.expected[i] != result[i] {
-				t.Errorf("%s != %s", result, test.expected)
-			}
-		}
-	}
-}
-
 func TestFillNillSlices(t *testing.T) {
 	// Nil
 	x := &struct {
@@ -148,83 +108,6 @@ func TestFillNillSlices(t *testing.T) {
 	}
 }
 
-func TestAddress(t *testing.T) {
-	tests := []struct {
-		network string
-		host    string
-		result  string
-	}{
-		{"tcp", "google.com", "tcp://google.com"},
-		{"foo", "google", "foo://google"},
-		{"123", "456", "123://456"},
-	}
-
-	for _, test := range tests {
-		result := Address(test.network, test.host)
-		if result != test.result {
-			t.Errorf("%s != %s", result, test.result)
-		}
-	}
-}
-
-func TestCopyMatching(t *testing.T) {
-	type Nested struct {
-		A int
-	}
-	type Test struct {
-		CopyA  int
-		CopyB  []string
-		CopyC  Nested
-		CopyD  *Nested
-		NoCopy int `restart:"true"`
-	}
-
-	from := Test{
-		CopyA: 1,
-		CopyB: []string{"friend", "foe"},
-		CopyC: Nested{
-			A: 2,
-		},
-		CopyD: &Nested{
-			A: 3,
-		},
-		NoCopy: 4,
-	}
-
-	to := Test{
-		CopyA: 11,
-		CopyB: []string{"foot", "toe"},
-		CopyC: Nested{
-			A: 22,
-		},
-		CopyD: &Nested{
-			A: 33,
-		},
-		NoCopy: 44,
-	}
-
-	// Copy empty fields
-	CopyMatchingTag(&from, &to, "restart", func(v string) bool {
-		return v != "true"
-	})
-
-	if to.CopyA != 1 {
-		t.Error("CopyA")
-	}
-	if len(to.CopyB) != 2 || to.CopyB[0] != "friend" || to.CopyB[1] != "foe" {
-		t.Error("CopyB")
-	}
-	if to.CopyC.A != 2 {
-		t.Error("CopyC")
-	}
-	if to.CopyD.A != 3 {
-		t.Error("CopyC")
-	}
-	if to.NoCopy != 44 {
-		t.Error("NoCopy")
-	}
-}
-
 func TestFillNil(t *testing.T) {
 	type A struct {
 		Slice []int
diff --git a/lib/stun/stun.go b/lib/stun/stun.go
index 191b39c5b..6f776d972 100644
--- a/lib/stun/stun.go
+++ b/lib/stun/stun.go
@@ -14,7 +14,7 @@ import (
 	"github.com/ccding/go-stun/stun"
 
 	"github.com/syncthing/syncthing/lib/config"
-	"github.com/syncthing/syncthing/lib/util"
+	"github.com/syncthing/syncthing/lib/svcutil"
 )
 
 const stunRetryInterval = 5 * time.Minute
@@ -159,7 +159,7 @@ func (s *Service) runStunForServer(ctx context.Context, addr string) {
 
 	var natType stun.NATType
 	var extAddr *stun.Host
-	err = util.CallWithContext(ctx, func() error {
+	err = svcutil.CallWithContext(ctx, func() error {
 		natType, extAddr, err = s.client.Discover()
 		return err
 	})
diff --git a/lib/svcutil/svcutil.go b/lib/svcutil/svcutil.go
index f9d5684b0..1db3d800a 100644
--- a/lib/svcutil/svcutil.go
+++ b/lib/svcutil/svcutil.go
@@ -223,3 +223,18 @@ func asNonContextError(ctx context.Context, err error) error {
 	}
 	return err
 }
+
+func CallWithContext(ctx context.Context, fn func() error) error {
+	var err error
+	done := make(chan struct{})
+	go func() {
+		err = fn()
+		close(done)
+	}()
+	select {
+	case <-done:
+		return err
+	case <-ctx.Done():
+		return ctx.Err()
+	}
+}
diff --git a/lib/testutils/testutils.go b/lib/testutil/testutil.go
index 09dc7e805..523b3a8d5 100644
--- a/lib/testutils/testutils.go
+++ b/lib/testutil/testutil.go
@@ -4,7 +4,7 @@
 // License, v. 2.0. If a copy of the MPL was not distributed with this file,
 // You can obtain one at https://mozilla.org/MPL/2.0/.
 
-package testutils
+package testutil
 
 import (
 	"errors"
@@ -25,6 +25,7 @@ func NewBlockingRW() *BlockingRW {
 		closeOnce: sync.Once{},
 	}
 }
+
 func (rw *BlockingRW) Read(_ []byte) (int, error) {
 	<-rw.c
 	return 0, ErrClosed
diff --git a/lib/ur/contract/contract.go b/lib/ur/contract/contract.go
index daae595cb..52f07ab2f 100644
--- a/lib/ur/contract/contract.go
+++ b/lib/ur/contract/contract.go
@@ -14,7 +14,7 @@ import (
 	"strconv"
 	"time"
 
-	"github.com/syncthing/syncthing/lib/util"
+	"github.com/syncthing/syncthing/lib/structutil"
 )
 
 type Report struct {
@@ -179,7 +179,7 @@ type Report struct {
 
 func New() *Report {
 	r := &Report{}
-	util.FillNil(r)
+	structutil.FillNil(r)
 	return r
 }
 
diff --git a/lib/versioner/util.go b/lib/versioner/util.go
index ffa0dd3fe..d01f33c0f 100644
--- a/lib/versioner/util.go
+++ b/lib/versioner/util.go
@@ -19,7 +19,7 @@ import (
 	"github.com/syncthing/syncthing/lib/config"
 	"github.com/syncthing/syncthing/lib/fs"
 	"github.com/syncthing/syncthing/lib/osutil"
-	"github.com/syncthing/syncthing/lib/util"
+	"github.com/syncthing/syncthing/lib/stringutil"
 )
 
 var (
@@ -126,7 +126,6 @@ func retrieveVersions(fileSystem fs.Filesystem) (map[string][]FileVersion, error
 
 		return nil
 	})
-
 	if err != nil {
 		return nil, err
 	}
@@ -153,7 +152,7 @@ func archiveFile(method fs.CopyRangeMethod, srcFs, dstFs fs.Filesystem, filePath
 	if err != nil {
 		if fs.IsNotExist(err) {
 			l.Debugln("creating versions dir")
-			err := dstFs.MkdirAll(".", 0755)
+			err := dstFs.MkdirAll(".", 0o755)
 			if err != nil {
 				return err
 			}
@@ -166,7 +165,7 @@ func archiveFile(method fs.CopyRangeMethod, srcFs, dstFs fs.Filesystem, filePath
 	file := filepath.Base(filePath)
 	inFolderPath := filepath.Dir(filePath)
 
-	err = dstFs.MkdirAll(inFolderPath, 0755)
+	err = dstFs.MkdirAll(inFolderPath, 0o755)
 	if err != nil && !fs.IsExist(err) {
 		l.Debugln("archiving", filePath, err)
 		return err
@@ -253,7 +252,7 @@ func restoreFile(method fs.CopyRangeMethod, src, dst fs.Filesystem, filePath str
 		return err
 	}
 
-	_ = dst.MkdirAll(filepath.Dir(filePath), 0755)
+	_ = dst.MkdirAll(filepath.Dir(filePath), 0o755)
 	err := osutil.RenameOrCopy(method, src, dst, sourceFile, filePath)
 	_ = dst.Chtimes(filePath, sourceMtime, sourceMtime)
 	return err
@@ -285,7 +284,7 @@ func findAllVersions(fs fs.Filesystem, filePath string) []string {
 		l.Warnln("globbing:", err, "for", pattern)
 		return nil
 	}
-	versions = util.UniqueTrimmedStrings(versions)
+	versions = stringutil.UniqueTrimmedStrings(versions)
 	sort.Strings(versions)
 
 	return versions