Add AdGuard DNS filter support

route/rule_headless.go

@@ -142,6 +142,15 @@ func NewDefaultHeadlessRule(router adapter.Router, options option.DefaultHeadles
 			rule.allItems = append(rule.allItems, item)
 		}
 	}
+	if len(options.AdGuardDomain) > 0 {
+		item := NewAdGuardDomainItem(options.AdGuardDomain)
+		rule.destinationAddressItems = append(rule.destinationAddressItems, item)
+		rule.allItems = append(rule.allItems, item)
+	} else if options.AdGuardDomainMatcher != nil {
+		item := NewRawAdGuardDomainItem(options.AdGuardDomainMatcher)
+		rule.destinationAddressItems = append(rule.destinationAddressItems, item)
+		rule.allItems = append(rule.allItems, item)
+	}
 	return rule, nil
 }
 

route/rule_item_adguard.go

@@ -0,0 +1,43 @@
+package route
+
+import (
+	"strings"
+
+	"github.com/sagernet/sing-box/adapter"
+	"github.com/sagernet/sing/common/domain"
+)
+
+var _ RuleItem = (*AdGuardDomainItem)(nil)
+
+type AdGuardDomainItem struct {
+	matcher *domain.AdGuardMatcher
+}
+
+func NewAdGuardDomainItem(ruleLines []string) *AdGuardDomainItem {
+	return &AdGuardDomainItem{
+		domain.NewAdGuardMatcher(ruleLines),
+	}
+}
+
+func NewRawAdGuardDomainItem(matcher *domain.AdGuardMatcher) *AdGuardDomainItem {
+	return &AdGuardDomainItem{
+		matcher,
+	}
+}
+
+func (r *AdGuardDomainItem) Match(metadata *adapter.InboundContext) bool {
+	var domainHost string
+	if metadata.Domain != "" {
+		domainHost = metadata.Domain
+	} else {
+		domainHost = metadata.Destination.Fqdn
+	}
+	if domainHost == "" {
+		return false
+	}
+	return r.matcher.Match(strings.ToLower(domainHost))
+}
+
+func (r *AdGuardDomainItem) String() string {
+	return "!adguard_domain_rules=<binary>"
+}