Fix overture with NAT mode

mobile/src/main/scala/com/github/shadowsocks/BaseService.scala

@@ -123,7 +123,7 @@ trait BaseService extends Service {
     false
   } else true
 
-  def getExternalIp() {
+  def getExternalIp(): String = {
     val url = "http://icanhazip.com"
     val client = new OkHttpClient.Builder()
       .connectTimeout(10, TimeUnit.SECONDS)
@@ -133,7 +133,11 @@ trait BaseService extends Service {
     val request = new Request.Builder()
       .url(url)
       .build()
-    client.newCall(request).execute().body.string
+    val response = client.newCall(request).execute()
+    if (response.isSuccessful)
+      response.body.string.trim
+    else
+      ""
   }
 
   def connect() {

mobile/src/main/scala/com/github/shadowsocks/ShadowsocksNatService.scala

@@ -89,9 +89,9 @@ class ShadowsocksNatService extends BaseService {
         ConfigUtils.OVERTURE_DIRECT.formatLocal(Locale.ENGLISH,
           profile.localPort + 53, // Local Port
           "119.29.29.29", // Primary DNS 1
-          "tcp", // DNS type of Primary DNS 1
+          "udp", // DNS type of Primary DNS 1
           "114.114.114.114", // Primary DNS 2
-          "tcp", // DNS type of Primary DNS 2
+          "udp", // DNS type of Primary DNS 2
           profile.remoteDns, // Alternative DNS
           "127.0.0.1:" + profile.localPort, // Local SOCKS5 Proxy
           externalIp) // External IP