Fix lint errors

dns/client.go

@@ -61,10 +61,7 @@ type ClientOptions struct {
 }
 
 func NewClient(options ClientOptions) *Client {
-	cacheCapacity := options.CacheCapacity
-	if cacheCapacity < 1024 {
-		cacheCapacity = 1024
-	}
+	cacheCapacity := max(options.CacheCapacity, 1024)
 	client := &Client{
 		ctx:               options.Context,
 		timeout:           options.Timeout,
@@ -426,10 +423,7 @@ func (c *Client) loadResponse(question dns.Question, transport adapter.DNSTransp
 		c.cache.Remove(key)
 		return nil, 0, false
 	}
-	nowTTL := int(expireAt.Sub(timeNow).Seconds())
-	if nowTTL < 0 {
-		nowTTL = 0
-	}
+	nowTTL := max(int(expireAt.Sub(timeNow).Seconds()), 0)
 	response = response.Copy()
 	normalizeTTL(response, uint32(nowTTL))
 	return response, nowTTL, false

dns/router.go

@@ -1011,33 +1011,6 @@ func lookupDNSRuleSetMetadata(router adapter.Router, tag string, metadataOverrid
 	return ruleSet.Metadata(), nil
 }
 
-func referencedDNSRuleSetTags(rules []option.DNSRule) []string {
-	tagMap := make(map[string]bool)
-	var walkRule func(rule option.DNSRule)
-	walkRule = func(rule option.DNSRule) {
-		switch rule.Type {
-		case "", C.RuleTypeDefault:
-			for _, tag := range rule.DefaultOptions.RuleSet {
-				tagMap[tag] = true
-			}
-		case C.RuleTypeLogical:
-			for _, subRule := range rule.LogicalOptions.Rules {
-				walkRule(subRule)
-			}
-		}
-	}
-	for _, rule := range rules {
-		walkRule(rule)
-	}
-	tags := make([]string, 0, len(tagMap))
-	for tag := range tagMap {
-		if tag != "" {
-			tags = append(tags, tag)
-		}
-	}
-	return tags
-}
-
 func validateLegacyDNSModeDisabledRules(router adapter.Router, rules []option.DNSRule, metadataOverrides map[string]adapter.RuleSetMetadata) error {
 	var seenEvaluate bool
 	for i, rule := range rules {

dns/router_test.go

@@ -4,7 +4,6 @@ import (
 	"context"
 	"net"
 	"net/netip"
-	"strings"
 	"sync"
 	"testing"
 	"time"
@@ -113,14 +112,6 @@ func (r *fakeRouter) RuleSet(tag string) (adapter.RuleSet, bool) {
 	return ruleSet, loaded
 }
 
-func (r *fakeRouter) setRuleSet(tag string, ruleSet adapter.RuleSet) {
-	r.access.Lock()
-	defer r.access.Unlock()
-	if r.ruleSets == nil {
-		r.ruleSets = make(map[string]adapter.RuleSet)
-	}
-	r.ruleSets[tag] = ruleSet
-}
 func (r *fakeRouter) Rules() []adapter.Rule                      { return nil }
 func (r *fakeRouter) NeedFindProcess() bool                      { return false }
 func (r *fakeRouter) NeedFindNeighbor() bool                     { return false }
@@ -210,12 +201,6 @@ func (s *fakeRuleSet) updateMetadata(metadata adapter.RuleSetMetadata) {
 	}
 }
 
-func (s *fakeRuleSet) snapshotCallbacks() []adapter.RuleSetUpdateCallback {
-	s.access.Lock()
-	defer s.access.Unlock()
-	return s.callbacks.Array()
-}
-
 func (s *fakeRuleSet) refCount() int {
 	s.access.Lock()
 	defer s.access.Unlock()
@@ -322,26 +307,6 @@ func newTestRouterWithContextAndLogger(t *testing.T, ctx context.Context, rules
 	return router
 }
 
-func waitForLogMessageContaining(t *testing.T, entries <-chan log.Entry, done <-chan struct{}, substring string) log.Entry {
-	t.Helper()
-	timeout := time.After(time.Second)
-	for {
-		select {
-		case entry, ok := <-entries:
-			if !ok {
-				t.Fatal("log subscription closed")
-			}
-			if strings.Contains(entry.Message, substring) {
-				return entry
-			}
-		case <-done:
-			t.Fatal("log subscription closed")
-		case <-timeout:
-			t.Fatalf("timed out waiting for log message containing %q", substring)
-		}
-	}
-}
-
 func fixedQuestion(name string, qType uint16) mDNS.Question {
 	return mDNS.Question{
 		Name:   mDNS.Fqdn(name),

dns/transport/local/local_darwin_stun.go

@@ -0,0 +1,15 @@
+//go:build darwin && !cgo
+
+package local
+
+import (
+	"context"
+
+	E "github.com/sagernet/sing/common/exceptions"
+
+	mDNS "github.com/miekg/dns"
+)
+
+func (t *Transport) systemExchange(ctx context.Context, message *mDNS.Msg) (*mDNS.Msg, error) {
+	return nil, E.New(`local DNS server requires CGO on darwin, rebuild with CGO_ENABLED=1`)
+}