1 files changed, 97 insertions, 18 deletions
diff --git a/app/src/main/java/se/leap/bitmaskclient/providersetup/connectivity/DnsResolver.java b/app/src/main/java/se/leap/bitmaskclient/providersetup/connectivity/DnsResolver.java
index 5655e7b7..e8249692 100644
--- a/app/src/main/java/se/leap/bitmaskclient/providersetup/connectivity/DnsResolver.java
+++ b/app/src/main/java/se/leap/bitmaskclient/providersetup/connectivity/DnsResolver.java
@@ -1,5 +1,9 @@
 package se.leap.bitmaskclient.providersetup.connectivity;
 
+import static java.net.InetAddress.getByName;
+
+import android.util.Log;
+
 import androidx.annotation.NonNull;
 
 import java.net.InetAddress;
@@ -9,34 +13,109 @@ import java.util.List;
 
 import de.blinkt.openvpn.core.VpnStatus;
 import okhttp3.Dns;
+import okhttp3.HttpUrl;
+import okhttp3.OkHttpClient;
+import okhttp3.dnsoverhttps.DnsOverHttps;
 import se.leap.bitmaskclient.base.models.Provider;
 import se.leap.bitmaskclient.base.models.ProviderObservable;
 import se.leap.bitmaskclient.base.utils.IPAddress;
 
-class DnsResolver implements Dns {
+public class DnsResolver implements Dns {
+    OkHttpClient dohHttpClient;
+    boolean preferDoH;
+
+    public DnsResolver(OkHttpClient dohHttpClient, boolean preferDoH) {
+        this.dohHttpClient = dohHttpClient;
+        this.preferDoH = preferDoH;
+    }
 
+    @NonNull
     @Override
     public List<InetAddress> lookup(@NonNull String hostname) throws UnknownHostException {
+        Log.d("DNS", "trying to resolve DNS for " + hostname);
+        List<InetAddress> list = null;
+        if (preferDoH) {
+            if ((list = tryLookupDoH(hostname)) == null) {
+                list  = tryLookupSystemDNS(hostname);
+            }
+        } else {
+            if ((list = tryLookupSystemDNS(hostname)) == null) {
+                list = tryLookupDoH(hostname);
+            }
+        }
+
+        if (list != null) {
+            return list;
+        }
+
+        Log.d("DNS", "try hard coded IPs");
+        // let's check if there's an hard-coded IP we can use
+        ProviderObservable observable = ProviderObservable.getInstance();
+        Provider currentProvider;
+        if (observable.getProviderForDns() != null) {
+            currentProvider = observable.getProviderForDns();
+        } else {
+            currentProvider = observable.getCurrentProvider();
+        }
+        String ip = currentProvider.getIpForHostname(hostname);
+        if (!ip.isEmpty()) {
+            VpnStatus.logWarning("[API] Normal DNS resolution for " + hostname + " seems to be blocked. Circumventing.");
+            ArrayList<InetAddress> addresses = new ArrayList<>();
+            addresses.add(InetAddress.getByAddress(hostname, IPAddress.asBytes(ip)));
+            return addresses;
+        } else {
+            VpnStatus.logWarning("[API] Could not resolve DNS for " + hostname);
+            throw new UnknownHostException("Hostname " + hostname + " not found");
+        }
+    }
+
+    private List<InetAddress> tryLookupSystemDNS(@NonNull String hostname) throws RuntimeException, UnknownHostException {
         try {
+            Log.d("DNS", "trying to resolve " + hostname + "with system DNS");
             return Dns.SYSTEM.lookup(hostname);
         } catch (UnknownHostException e) {
-            ProviderObservable observable = ProviderObservable.getInstance();
-            Provider currentProvider;
-            if (observable.getProviderForDns() != null) {
-                currentProvider = observable.getProviderForDns();
-            } else {
-                currentProvider = observable.getCurrentProvider();
-            }
-            String ip = currentProvider.getIpForHostname(hostname);
-            if (!ip.isEmpty()) {
-                VpnStatus.logWarning("[API] Normal DNS resolution for " + hostname + " seems to be blocked. Circumventing.");
-                ArrayList<InetAddress> addresses = new ArrayList<>();
-                addresses.add(InetAddress.getByAddress(hostname, IPAddress.asBytes(ip)));
-                return addresses;
-            } else {
-                VpnStatus.logWarning("[API] Could not resolve DNS for " + hostname);
-                throw new UnknownHostException("Hostname " + hostname + " not found");
-            }
+            e.printStackTrace();
+            return null;
+        }
+    }
+
+    private List<InetAddress> tryLookupDoH(@NonNull String hostname) throws UnknownHostException {
+        DnsOverHttps njallaDoH = new DnsOverHttps.Builder().client(dohHttpClient)
+                .url(HttpUrl.get("https://dns.njal.la/dns-query"))
+                .bootstrapDnsHosts(getByName("95.215.19.53"), getByName("2001:67c:2354:2::53"))
+                .build();
+        try {
+            Log.d("DNS", "DoH via dns.njal.la");
+            return njallaDoH.lookup(hostname);
+        } catch (UnknownHostException e) {
+            e.printStackTrace();
+            Log.e("DNS", "DoH via dns.njal.la failed");
+        }
+
+        DnsOverHttps quad9 = new DnsOverHttps.Builder().client(dohHttpClient)
+                .url(HttpUrl.get("https://dns.quad9.net/dns-query"))
+                .bootstrapDnsHosts(getByName("9.9.9.9"), getByName("149.112.112.112"), getByName("2620:fe::fe"), getByName("2620:fe::9"))
+                .build();
+        try {
+            Log.d("DNS", "DoH via dns.quad9.net");
+            return quad9.lookup(hostname);
+        } catch (UnknownHostException e) {
+            e.printStackTrace();
+            Log.e("DNS", "DoH via dns.quad9.net failed");
+        }
+
+        DnsOverHttps cloudFlareDoHClient = new DnsOverHttps.Builder().client(dohHttpClient)
+                .url(HttpUrl.get("https://1.1.1.1/dns-query"))
+                .bootstrapDnsHosts(getByName("1.1.1.1"), getByName("1.0.0.1"))
+                .build();
+
+        try {
+            Log.d("DNS", "DoH via cloudflare 1.1.1.1");
+            return cloudFlareDoHClient.lookup(hostname);
+        } catch (UnknownHostException e) {
+            e.printStackTrace();
+            Log.e("DNS", "DoH via cloudflare failed");
         }
+        return null;
     }
 }