Add support for XEP-0418: DNS Queries over XMPP (DoX)

Fixes SMACK-862.

smack-core/src/main/java/org/jivesoftware/smack/util/RandomUtil.java

@@ -43,4 +43,8 @@ public class RandomUtil {
     public static int nextSecureRandomInt(int bound) {
         return SECURE_RANDOM.get().nextInt(bound);
     }
+
+    public static int nextSecureRandomInt() {
+        return SECURE_RANDOM.get().nextInt();
+    }
 }

smack-core/src/main/java/org/jivesoftware/smack/util/stringencoder/Base64.java

@@ -39,18 +39,17 @@ public class Base64 {
     }
 
     public static final String encodeToString(byte[] input) {
-        byte[] bytes = encode(input);
-        try {
-            return new String(bytes, StringUtils.USASCII);
-        } catch (UnsupportedEncodingException e) {
-            throw new AssertionError(e);
-        }
+        return base64encoder.encodeToString(input);
     }
 
     public static final String encodeToString(byte[] input, int offset, int len) {
         return encodeToString(slice(input, offset, len));
     }
 
+    public static final String encodeToStringWithoutPadding(byte[] input) {
+        return base64encoder.encodeToStringWithoutPadding(input);
+    }
+
     public static final byte[] encode(byte[] input) {
         return base64encoder.encode(input);
     }
@@ -103,6 +102,8 @@ public class Base64 {
 
         String encodeToString(byte[] input);
 
+        String encodeToStringWithoutPadding(byte[] input);
+
         byte[] encode(byte[] input);
     }
 }

smack-core/src/test/java/org/jivesoftware/smack/test/util/SmackTestSuite.java

@@ -39,6 +39,11 @@ public class SmackTestSuite {
                 return Base64.getEncoder().encodeToString(input);
             }
 
+            @Override
+            public String encodeToStringWithoutPadding(byte[] input) {
+                return Base64.getEncoder().withoutPadding().encodeToString(input);
+            }
+
             @Override
             public byte[] encode(byte[] input) {
                 return Base64.getEncoder().encode(input);