feat(dns): add explicit mdns resolver

config/config.go

@@ -1240,6 +1240,11 @@ func parseNameServer(servers []string, respectRules bool, preferH3 bool) ([]dns.
 			dnsNetType = "quic" // DNS over QUIC
 		case "system":
 			dnsNetType = "system" // System DNS
+		case "mdns":
+			dnsNetType = "mdns" // Multicast DNS
+			if u.Host != "" || u.Path != "" || u.RawQuery != "" || u.Fragment != "" {
+				err = errors.New("mDNS nameserver does not accept an address or parameters")
+			}
 		case "ts", "tailscale":
 			addr = u.Host
 			dnsNetType = "tailscale" // Tailscale DNS via proxy name
@@ -1274,7 +1279,7 @@ func parseNameServer(servers []string, respectRules bool, preferH3 bool) ([]dns.
 			return nil, fmt.Errorf("DNS NameServer[%d] format error: %s", idx, err.Error())
 		}
 
-		if respectRules && len(proxyName) == 0 {
+		if respectRules && len(proxyName) == 0 && dnsNetType != "mdns" {
 			proxyName = dns.RespectRules
 		}
 

config/dns_nameserver_test.go

@@ -0,0 +1,36 @@
+package config
+
+import (
+	"testing"
+
+	"github.com/metacubex/mihomo/common/orderedmap"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestParseMDNSNameServer(t *testing.T) {
+	nameservers, err := parseNameServer([]string{"mdns://"}, true, false)
+	require.NoError(t, err)
+	require.Len(t, nameservers, 1)
+	assert.Equal(t, "mdns", nameservers[0].Net)
+	assert.Empty(t, nameservers[0].Addr)
+	assert.Empty(t, nameservers[0].ProxyName)
+}
+
+func TestParseMDNSNameServerPolicy(t *testing.T) {
+	rawPolicy := orderedmap.New[string, any]()
+	rawPolicy.Set("+.local", []string{"mdns://"})
+
+	policy, err := parseNameServerPolicy(rawPolicy, nil, false, false)
+	require.NoError(t, err)
+	require.Len(t, policy, 1)
+	assert.Equal(t, "+.local", policy[0].Domain)
+	require.Len(t, policy[0].NameServers, 1)
+	assert.Equal(t, "mdns", policy[0].NameServers[0].Net)
+}
+
+func TestParseMDNSNameServerRejectsAddress(t *testing.T) {
+	_, err := parseNameServer([]string{"mdns://127.0.0.1"}, false, false)
+	assert.ErrorContains(t, err, "does not accept an address or parameters")
+}