DNS cleanup

arc-core/src/arc/Application.java

@@ -3,6 +3,8 @@
 import arc.struct.*;
 import arc.util.*;
 
+import java.net.*;
+
 public interface Application extends Disposable{
 
     /** Returns a list of all the application listeners used. */
@@ -96,6 +98,8 @@ default boolean openURI(String URI){
         return false;
     }
 
+    default void getDnsServers(Seq<InetSocketAddress> out){}
+
     /** Posts a runnable on the main loop thread.*/
     void post(Runnable runnable);
 

backends/backend-android/src/arc/backend/android/AndroidApplication.java

@@ -16,6 +16,8 @@
 import arc.struct.*;
 import arc.util.*;
 
+import java.net.*;
+
 /**
  * An implementation of the {@link Application} interface for Android. Create an {@link Activity} that derives from this class. In
  * the {@link Activity#onCreate(Bundle)} method call the {@link #initialize(ApplicationListener)} method specifying the
@@ -166,6 +168,31 @@ protected void hideStatusBar(boolean hide){
         getWindow().getDecorView().setSystemUiVisibility(0x1);
     }
 
+    @Override
+    public void getDnsServers(Seq<InetSocketAddress> out){
+        if(getVersion() < 21) return; //needs API level 21
+
+        try{
+            ConnectivityManager cm = getSystemService(ConnectivityManager.class);
+            Network network = cm.getActiveNetwork();
+            if(network == null){
+                // if the device is offline, there's no active network
+                return;
+            }
+
+            LinkProperties lp = cm.getLinkProperties(network);
+            if(lp == null){
+                // can be null for an unknown network, which may happen if networks change
+                return;
+            }
+
+            for(InetAddress address : lp.getDnsServers()){
+                out.add(new InetSocketAddress(address, 53));
+            }
+        }catch(Throwable ignored){
+        }
+    }
+
     @Override
     public void onWindowFocusChanged(boolean hasFocus){
         super.onWindowFocusChanged(hasFocus);

extensions/arcnet/src/arc/net/dns/ArcDns.java

@@ -1,13 +1,13 @@
 package arc.net.dns;
 
+import arc.*;
 import arc.math.*;
 import arc.struct.*;
 import arc.util.*;
 import arc.util.io.Streams.*;
 
 import java.io.*;
 import java.net.*;
-import java.nio.charset.*;
 
 public final class ArcDns{
 
@@ -26,7 +26,7 @@ public final class ArcDns{
     }
 
     public static Seq<NameserverProvider> getNameserverProviders(){
-        return nameserverProviders.copy();
+        return nameserverProviders;
     }
 
     /** Set a new ordered list of resolver config providers. */
@@ -38,25 +38,32 @@ public static void setNameserverProviders(Seq<NameserverProvider> providers){
 
     /** Returns all located servers */
     public static Seq<InetSocketAddress> getNameservers(){
-        return nameservers.copy();
+        return nameservers;
     }
 
     public static void refreshNameservers(){
         nameservers.clear();
 
+        if(Core.app != null){
+            Core.app.getDnsServers(nameservers);
+        }
+
         for(NameserverProvider provider : nameserverProviders){
             if(provider.isEnabled()){
                 try{
-                    provider.initialize();
                     nameservers.addAll(provider.getNameservers());
                     // Stop when a name server is found
                     if(!nameservers.isEmpty()) return;
-                }catch(InitializationException e){
+                }catch(Exception e){
                     Log.warn("[DNS] Failed to initialize provider: @", e);
                 }
             }
         }
 
+        for(InetSocketAddress server : nameservers){
+            Log.debug("[DNS] Added @ to nameservers", server);
+        }
+
         // Add localhost as nameserver if no suitable nameserver provider found
         nameservers.add(new InetSocketAddress(InetAddress.getLoopbackAddress(), dnsResolverPort));
     }
@@ -101,7 +108,7 @@ public static Seq<SRVRecord> getSrvRecords(String domain, InetSocketAddress name
                 // Domain
                 for(String part : domain.split("\\.")){
                     out.writeByte(part.length());
-                    out.write(part.getBytes(StandardCharsets.UTF_8));
+                    out.write(part.getBytes(Strings.utf8));
                 }
                 out.writeByte(0);
 

extensions/arcnet/src/arc/net/dns/JndiContextNameserverProvider.java

@@ -19,41 +19,12 @@
  * <a href="https://docs.oracle.com/javase/8/docs/technotes/guides/jndi/jndi-dns.html">JNDI DNS Service Provider</a>.
  */
 public final class JndiContextNameserverProvider implements NameserverProvider{
-    private InnerJndiContextNameserverProvider inner;
-
-    public JndiContextNameserverProvider(){
-        if(!OS.isAndroid){
-            try{
-                inner = new InnerJndiContextNameserverProvider();
-            }catch(Throwable e){
-                Log.debug("[DNS] JNDI DNS not available");
-            }
-        }
-    }
-
-    @Override
-    public void initialize(){
-        inner.initialize();
-    }
 
     @Override
     public Seq<InetSocketAddress> getNameservers(){
-        return inner.getNameservers();
-    }
-
-    @Override
-    public boolean isEnabled(){
-        return inner != null;
-    }
-
-    private static final class InnerJndiContextNameserverProvider extends AbstractNameserverProvider{
-        static{
-            Log.debug("[DNS] JNDI class: @", DirContext.class.getName());
-        }
+        try{
+            Seq<InetSocketAddress> result = new Seq<>();
 
-        @Override
-        public void initialize(){
-            reset();
             Hashtable<String, String> env = new Hashtable<>();
             env.put(Context.INITIAL_CONTEXT_FACTORY, "com.sun.jndi.dns.DnsContextFactory");
             // http://mail.openjdk.java.net/pipermail/net-dev/2017-March/010695.html
@@ -84,12 +55,21 @@ public void initialize(){
                             port = dnsResolverPort;
                         }
 
-                        addNameServer(new InetSocketAddress(host, port));
+                        result.add(new InetSocketAddress(host, port));
                     }catch(URISyntaxException e){
                         Log.debug("[DNS] Could not parse @ as a dns server, ignoring: @", server, e);
                     }
                 }
             }
+
+            return result;
+        }catch(Throwable t){
+            return new Seq<>();
         }
     }
+
+    @Override
+    public boolean isEnabled(){
+        return !OS.isAndroid && !OS.isIos;
+    }
 }

extensions/arcnet/src/arc/net/dns/NameserverProvider.java

@@ -9,9 +9,6 @@
 import java.net.*;
 
 public interface NameserverProvider{
-    /** Initializes the servers. */
-    void initialize() throws InitializationException;
-
     /** Returns all located servers, which may be empty. */
     Seq<InetSocketAddress> getNameservers();
 

extensions/arcnet/src/arc/net/dns/ResolvConfNameserverProvider.java

@@ -5,27 +5,29 @@
 package arc.net.dns;
 
 import arc.files.*;
+import arc.struct.*;
 import arc.util.*;
 
 import java.io.*;
 import java.net.*;
 import java.util.*;
 
-import static arc.net.dns.ArcDns.dnsResolverPort;
+import static arc.net.dns.ArcDns.*;
 
-public final class ResolvConfNameserverProvider extends AbstractNameserverProvider{
+public final class ResolvConfNameserverProvider implements NameserverProvider{
 
     @Override
-    public void initialize(){
-        reset();
+    public Seq<InetSocketAddress> getNameservers(){
+        Seq<InetSocketAddress> out = new Seq<>();
         // first try the default unix config path
-        if(!tryParseResolveConf("/etc/resolv.conf")){
+        if(!tryParseResolveConf("/etc/resolv.conf", out)){
             // then fallback to netware
-            tryParseResolveConf("sys:/etc/resolv.cfg");
+            tryParseResolveConf("sys:/etc/resolv.cfg", out);
         }
+        return out;
     }
 
-    private boolean tryParseResolveConf(String path){
+    private boolean tryParseResolveConf(String path, Seq<InetSocketAddress> out){
         Fi conf = new Fi(path);
 
         if(conf.exists()){
@@ -36,11 +38,11 @@ private boolean tryParseResolveConf(String path){
                     if(!tokenizer.hasMoreTokens()) continue;
 
                     if(tokenizer.nextToken().equals("nameserver")){
-                        addNameServer(new InetSocketAddress(tokenizer.nextToken(), dnsResolverPort));
+                        out.add(new InetSocketAddress(tokenizer.nextToken(), dnsResolverPort));
                     }
                 }
                 return true;
-            }catch(IOException ignored){
+            }catch(Exception ignored){
             }
         }
 

extensions/arcnet/src/arc/net/dns/SRVRecord.java

@@ -15,6 +15,17 @@ public SRVRecord(long ttl, int priority, int weight, int port, String target){
         this.target = target;
     }
 
+    @Override
+    public String toString(){
+        return "SRVRecord{" +
+        "ttl=" + ttl +
+        ", priority=" + priority +
+        ", weight=" + weight +
+        ", port=" + port +
+        ", target='" + target + '\'' +
+        '}';
+    }
+
     @Override
     public int compareTo(SRVRecord o){
         if(this.priority != o.priority){

extensions/arcnet/src/arc/net/dns/WellKnownNameserverProvider.java

@@ -7,18 +7,13 @@
 import static arc.net.dns.ArcDns.dnsResolverPort;
 
 public final class WellKnownNameserverProvider implements NameserverProvider{
-
     private final Seq<InetSocketAddress> nameservers = Seq.with(
     new InetSocketAddress("1.1.1.1", dnsResolverPort),   // Cloudflare
     new InetSocketAddress("8.8.8.8", dnsResolverPort)    // Google
     );
 
-    @Override
-    public void initialize(){
-    }
-
     @Override
     public Seq<InetSocketAddress> getNameservers(){
-        return nameservers.copy();
+        return nameservers;
     }
 }