Feature: add custom DNS support (#56)

tunnel/mode.go

@@ -10,9 +10,9 @@ type Mode int
 var (
 	// ModeMapping is a mapping for Mode enum
 	ModeMapping = map[string]Mode{
-		"Global": Global,
-		"Rule":   Rule,
-		"Direct": Direct,
+		Global.String(): Global,
+		Rule.String():   Rule,
+		Direct.String(): Direct,
 	}
 )
 
@@ -34,6 +34,18 @@ func (m *Mode) UnmarshalJSON(data []byte) error {
 	return nil
 }
 
+// UnmarshalYAML unserialize Mode with yaml
+func (m *Mode) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	var tp string
+	unmarshal(&tp)
+	mode, exist := ModeMapping[tp]
+	if !exist {
+		return errors.New("invalid mode")
+	}
+	*m = mode
+	return nil
+}
+
 // MarshalJSON serialize Mode
 func (m Mode) MarshalJSON() ([]byte, error) {
 	return json.Marshal(m.String())

tunnel/tunnel.go

@@ -1,11 +1,13 @@
 package tunnel
 
 import (
+	"net"
 	"sync"
 	"time"
 
 	InboundAdapter "github.com/Dreamacro/clash/adapters/inbound"
 	C "github.com/Dreamacro/clash/constant"
+	"github.com/Dreamacro/clash/dns"
 	"github.com/Dreamacro/clash/log"
 
 	"gopkg.in/eapache/channels.v1"
@@ -23,6 +25,7 @@ type Tunnel struct {
 	proxies    map[string]C.Proxy
 	configLock *sync.RWMutex
 	traffic    *C.Traffic
+	resolver   *dns.Resolver
 
 	// Outbound Rule
 	mode Mode
@@ -72,6 +75,11 @@ func (t *Tunnel) SetMode(mode Mode) {
 	t.mode = mode
 }
 
+// SetResolver change the resolver of tunnel
+func (t *Tunnel) SetResolver(resolver *dns.Resolver) {
+	t.resolver = resolver
+}
+
 func (t *Tunnel) process() {
 	queue := t.queue.Out()
 	for {
@@ -81,10 +89,41 @@ func (t *Tunnel) process() {
 	}
 }
 
+func (t *Tunnel) resolveIP(host string) (net.IP, error) {
+	if t.resolver == nil {
+		ipAddr, err := net.ResolveIPAddr("ip", host)
+		if err != nil {
+			return nil, err
+		}
+
+		return ipAddr.IP, nil
+	}
+
+	return t.resolver.ResolveIP(host)
+}
+
 func (t *Tunnel) handleConn(localConn C.ServerAdapter) {
 	defer localConn.Close()
 	metadata := localConn.Metadata()
 
+	if metadata.Source == C.REDIR && t.resolver != nil {
+		host, exist := t.resolver.IPToHost(*metadata.IP)
+		if exist {
+			metadata.Host = host
+			metadata.AddrType = C.AtypDomainName
+		}
+	} else if metadata.IP == nil && metadata.AddrType == C.AtypDomainName {
+		ip, err := t.resolveIP(metadata.Host)
+		if err != nil {
+			log.Debugln("[DNS] resolve %s error: %s", metadata.Host, err.Error())
+		} else {
+			log.Debugln("[DNS] %s --> %s", metadata.Host, ip.String())
+			metadata.IP = &ip
+		}
+	} else {
+		log.Debugln("[DNS] unknown%#v", metadata)
+	}
+
 	var proxy C.Proxy
 	switch t.mode {
 	case Direct: