Debug info: private DNS

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

@@ -441,6 +441,36 @@ public class ConnectionHelper {
         return null;
     }
 
+    static Boolean isPrivateDnsActive(Context context) {
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M)
+            return null;
+        ConnectivityManager cm = Helper.getSystemService(context, ConnectivityManager.class);
+        if (cm == null)
+            return null;
+        Network active = cm.getActiveNetwork();
+        if (active == null)
+            return null;
+        LinkProperties props = cm.getLinkProperties(active);
+        if (props == null)
+            return null;
+        return props.isPrivateDnsActive();
+    }
+
+    static String getPrivateDnsServerName(Context context) {
+        if (Build.VERSION.SDK_INT < Build.VERSION_CODES.M)
+            return null;
+        ConnectivityManager cm = Helper.getSystemService(context, ConnectivityManager.class);
+        if (cm == null)
+            return null;
+        Network active = cm.getActiveNetwork();
+        if (active == null)
+            return null;
+        LinkProperties props = cm.getLinkProperties(active);
+        if (props == null)
+            return null;
+        return props.getPrivateDnsServerName();
+    }
+
     static boolean isIoError(Throwable ex) {
         if (ex instanceof MessagingException &&
                 ex.getMessage() != null &&

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

@@ -1036,8 +1036,6 @@ public class DebugHelper {
                         "\r\n");
                 size += write(os, "   caps=" + c + "\r\n");
                 size += write(os, "   props=" + p + "\r\n\r\n");
-                size += write(os, "   private DNS=" +
-                        (p == null ? null : p.isPrivateDnsActive() + " (" + p.getPrivateDnsServerName() + ")") + "\r\n");
 
                 for (Network network : cm.getAllNetworks()) {
                     size += write(os, (network.equals(active) ? "active=" : "network=") + network + "\r\n");
@@ -1096,6 +1094,9 @@ public class DebugHelper {
                 size += write(os, "VPN active=" + ConnectionHelper.vpnActive(context) + "\r\n");
                 size += write(os, "Data saving=" + ConnectionHelper.isDataSaving(context) + "\r\n");
                 size += write(os, "Airplane=" + ConnectionHelper.airplaneMode(context) + "\r\n");
+                size += write(os, "Private" +
+                        " DNS=" + ConnectionHelper.isPrivateDnsActive(context) +
+                        " server=" + ConnectionHelper.getPrivateDnsServerName(context) + "\r\n");
                 if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M)
                     size += write(os, "Cleartext permitted= " +
                             NetworkSecurityPolicy.getInstance().isCleartextTrafficPermitted() + "\r\n");