DNS error handling

app/src/main/java/eu/faircode/email/DnsHelper.java

@@ -101,7 +101,7 @@ public class DnsHelper {
             String domain = UriHelper.getEmailDomain(email);
             if (domain == null)
                 continue;
-            DnsRecord[] records = _lookup(context, domain, "mx", CHECK_TIMEOUT, false);
+            DnsRecord[] records = _lookup(context, domain, "mx", CHECK_TIMEOUT);
             if (records.length == 0)
                 throw new UnknownHostException(domain);
         }
@@ -109,11 +109,25 @@ public class DnsHelper {
 
     @NonNull
     static DnsRecord[] lookup(Context context, String name, String type) {
-        return _lookup(context, name, type, LOOKUP_TIMEOUT, false);
+        return _lookup(context, name, type, LOOKUP_TIMEOUT);
     }
 
     @NonNull
-    private static DnsRecord[] _lookup(Context context, String name, String type, int timeout, boolean dnssec) {
+    private static DnsRecord[] _lookup(Context context, String name, String type, int timeout) {
+        try {
+            return _lookup(context, name, type, timeout, false);
+        } catch (Throwable ex) {
+            if (ex instanceof MultipleIoException ||
+                    ex instanceof ResolutionUnsuccessfulException)
+                Log.i(ex);
+            else
+                Log.e(ex);
+            return new DnsRecord[0];
+        }
+    }
+
+    @NonNull
+    private static DnsRecord[] _lookup(Context context, String name, String type, int timeout, boolean dnssec) throws IOException {
         SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
         boolean dns_custom = prefs.getBoolean("dns_custom", false);
 
@@ -148,7 +162,6 @@ public class DnsHelper {
                 throw new IllegalArgumentException(type);
         }
 
-        try {
         ResolverApi resolver = DnssecResolverApi.INSTANCE;
         AbstractDnsClient client = resolver.getClient();
 
@@ -273,16 +286,6 @@ public class DnsHelper {
             });
 
         return result.toArray(new DnsRecord[0]);
-        } catch (Throwable ex) {
-            if (ex instanceof MultipleIoException ||
-                    ex instanceof ResolutionUnsuccessfulException ||
-                    ex instanceof DnssecValidationFailedException ||
-                    ex instanceof DnssecResultNotAuthenticException)
-                Log.i(ex);
-            else
-                Log.e(ex);
-            return new DnsRecord[0];
-        }
     }
 
     static InetAddress getByName(Context context, String host) throws UnknownHostException {
@@ -316,7 +319,7 @@ public class DnsHelper {
         List<InetAddress> result = new ArrayList<>();
 
         boolean[] has46 = ConnectionHelper.has46(context);
-
+        try {
             if (has46[0])
                 for (DnsRecord a : _lookup(context, host, "a", LOOKUP_TIMEOUT, dnssec))
                     result.add(a.address);
@@ -329,6 +332,9 @@ public class DnsHelper {
                 throw new UnknownHostException(host);
 
             return result.toArray(new InetAddress[0]);
+        } catch (IOException ex) {
+            throw new UnknownHostException(ex.getMessage());
+        }
     }
 
     static void verifyDane(X509Certificate[] chain, String server, int port) throws CertificateException {