Reduce rule matching memory allocations

protocol/tailscale/dns_transport.go

@@ -129,7 +129,7 @@ func (t *DNSTransport) updateDNSServers(routeConfig *router.Config, dnsConfig *n
 			}
 			myResolvers = append(myResolvers, myResolver)
 		}
-		routes[domain.WithTrailingDot()] = myResolvers
+		routes[mDNS.CanonicalName(domain.WithTrailingDot())] = myResolvers
 	}
 	hosts := make(map[string][]netip.Addr)
 	for domain, addresses := range dnsConfig.Hosts {
@@ -275,14 +275,25 @@ func (t *DNSTransport) PreferredDomain(domain string) bool {
 	if t.acceptSearchDomain && len(searchDomains) > 0 && mDNS.CountLabel(domain) == 1 {
 		return true
 	}
+	canonicalDomain := mDNS.CanonicalName(domain)
 	for suffix := range routes {
-		if mDNS.IsSubDomain(suffix, domain) {
+		if matchDomainSuffix(canonicalDomain, suffix) {
 			return true
 		}
 	}
 	return false
 }
 
+func matchDomainSuffix(domain string, suffix string) bool {
+	if suffix == "." || suffix == "" {
+		return true
+	}
+	if !strings.HasSuffix(domain, suffix) {
+		return false
+	}
+	return len(domain) == len(suffix) || domain[len(domain)-len(suffix)-1] == '.'
+}
+
 func (t *DNSTransport) Exchange(ctx context.Context, message *mDNS.Msg) (*mDNS.Msg, error) {
 	done := make(chan struct{})
 	var (
@@ -375,8 +386,9 @@ func (t *DNSTransport) exchangeOnce(ctx context.Context, message *mDNS.Msg, allo
 		}
 		return
 	}
+	canonicalName := mDNS.CanonicalName(question.Name)
 	for domainSuffix, transports := range routes {
-		if mDNS.IsSubDomain(domainSuffix, question.Name) {
+		if matchDomainSuffix(canonicalName, domainSuffix) {
 			if len(transports) == 0 {
 				callback(&mDNS.Msg{
 					MsgHdr: mDNS.MsgHdr{

protocol/tailscale/endpoint.go

@@ -953,7 +953,7 @@ func (t *Endpoint) PreferredDomain(metadata *adapter.InboundContext, domain stri
 		}
 	}
 	for _, suffix := range t.routeSuffixes.Load() {
-		if mDNS.IsSubDomain(suffix, domain) {
+		if matchDomainSuffix(domain, suffix) {
 			return true
 		}
 	}
@@ -1000,7 +1000,7 @@ func (t *Endpoint) onReconfig(cfg *wgcfg.Config, routerCfg *router.Config, dnsCf
 	}
 	routeSuffixes := make([]string, 0, len(dnsCfg.Routes))
 	for fqdn := range dnsCfg.Routes {
-		routeSuffixes = append(routeSuffixes, fqdn.WithoutTrailingDot())
+		routeSuffixes = append(routeSuffixes, strings.ToLower(fqdn.WithoutTrailingDot()))
 	}
 	t.routeDomains.Store(routeDomains)
 	t.routeSuffixes.Store(routeSuffixes)