CODEC-311: Fix possible ArrayIndexOutOfBoundException thrown by RefinedSoundex.getMappingCode() (apache#219)

* CODEC-311: Fix possible ArrayIndexOutOfBoundException

Signed-off-by: Arthur Chan <arthur.chan@adalogics.com>

* CODEC-311: Add unit test

Signed-off-by: Arthur Chan <arthur.chan@adalogics.com>

* Use final

---------

Signed-off-by: Arthur Chan <arthur.chan@adalogics.com>
Co-authored-by: Gary Gregory <garydgregory@users.noreply.github.com>

Author: arthurscchan

src/main/java/org/apache/commons/codec/language/RefinedSoundex.java

@@ -173,7 +173,11 @@ char getMappingCode(final char c) {
         if (!Character.isLetter(c)) {
             return 0;
         }
-        return this.soundexMapping[Character.toUpperCase(c) - 'A'];
+        final int index = Character.toUpperCase(c) - 'A';
+        if (index < 0 || index >= this.soundexMapping.length) {
+            return 0;
+        }
+        return this.soundexMapping[index];
     }
 
     /**

src/test/java/org/apache/commons/codec/language/RefinedSoundexTest.java

@@ -79,6 +79,16 @@ public void testGetMappingCodeNonLetter() {
         assertEquals(0, code, "Code does not equals zero");
     }
 
+    @Test
+    public void testInvalidSoundexCharacter() {
+        final char[] invalid = new char[256];
+        for (int i = 0; i < invalid.length; i++) {
+            invalid[i] = (char)i;
+        }
+
+        assertEquals(new RefinedSoundex().encode(new String(invalid)), "A0136024043780159360205050136024043780159360205053");
+    }
+
     @Test
     public void testNewInstance() {
         assertEquals("D6043", new RefinedSoundex().soundex("dogs"));