Jetty 9.4.x : fix tries mistakenly throwing ArrayIndexOutOfBoundsExce…

…ption (#7503)

Fixes #7496 fix getBest() throwing ArrayIndexOutOfBoundsException on full tries

Fixing jetty-maven-plugin IT test javax-annotation-api failure

Signed-off-by: Ludovic Orban <lorban@bitronix.be>
Signed-off-by: Greg Wilkins <gregw@webtide.com>
Signed-off-by: Joakim Erdfelt <joakim.erdfelt@gmail.com>
Co-authored-by: Greg Wilkins <gregw@webtide.com>
Co-authored-by: Joakim Erdfelt <joakim.erdfelt@gmail.com>

jetty-util/src/main/java/org/eclipse/jetty/util/ArrayTernaryTrie.java

@@ -205,9 +205,9 @@ public boolean put(String s, V v)
                 // Do we need to create the new row?
                 if (t == _rows)
                 {
+                    _rows = (char)MathUtils.cappedAdd(_rows, 1, _key.length);
                     if (_rows == _key.length)
                         return false;
-                    _rows++;
                     _tree[row] = c;
                 }
 
@@ -435,6 +435,9 @@ private V getBest(int t, ByteBuffer b, int offset, int len)
         loop:
         for (int i = 0; i < len; i++)
         {
+            if (o + i >= b.limit())
+                return null;
+
             byte c = (byte)(b.get(o + i) & 0x7f);
             if (isCaseInsensitive())
                 c = (byte)StringUtil.lowercases[c];

jetty-util/src/main/java/org/eclipse/jetty/util/ArrayTrie.java

@@ -139,7 +139,7 @@ public ArrayTrie(int capacity)
         if (capacity > MAX_CAPACITY)
             throw new IllegalArgumentException("Capacity " + capacity + " > " + MAX_CAPACITY);
         _value = (V[])new Object[capacity + 1];
-        _rowIndex = new char[(capacity + 1) * 32];
+        _rowIndex = new char[(capacity + 1) * ROW_SIZE];
         _key = new String[capacity + 1];
     }
 
@@ -171,7 +171,8 @@ public boolean put(String s, V v)
                 t = _rowIndex[idx];
                 if (t == 0)
                 {
-                    if (++_rows >= _value.length)
+                    _rows = (char)MathUtils.cappedAdd(_rows, 1, _value.length);
+                    if (_rows == _value.length)
                         return false;
                     t = _rowIndex[idx] = _rows;
                 }
@@ -190,9 +191,10 @@ else if (c > 127)
                 t = big[c];
                 if (t == 0)
                 {
+                    _rows = (char)MathUtils.cappedAdd(_rows, 1, _value.length);
                     if (_rows == _value.length)
                         return false;
-                    t = big[c] = ++_rows;
+                    t = big[c] = _rows;
                 }
             }
         }
@@ -368,6 +370,9 @@ private V getBest(int t, ByteBuffer b, int offset, int len)
         int pos = b.position() + offset;
         for (int i = 0; i < len; i++)
         {
+            if (pos >= b.limit())
+                return null;
+
             byte c = b.get(pos++);
             int index = __lookup[c & 0x7f];
             if (index >= 0)

jetty-util/src/main/java/org/eclipse/jetty/util/MathUtils.java

@@ -62,4 +62,24 @@ public static long cappedAdd(long a, long b)
             return Long.MAX_VALUE;
         }
     }
+
+    /**
+     * Returns the sum of its arguments, capping to {@code maxValue}.
+     *
+     * @param a the first value
+     * @param b the second value
+     * @return the sum of the values, capped to {@code maxValue}
+     */
+    public static int cappedAdd(int a, int b, int maxValue)
+    {
+        try
+        {
+            int sum = Math.addExact(a, b);
+            return Math.min(sum, maxValue);
+        }
+        catch (ArithmeticException x)
+        {
+            return maxValue;
+        }
+    }
 }

jetty-util/src/test/java/org/eclipse/jetty/util/TrieTest.java

@@ -19,6 +19,7 @@
 package org.eclipse.jetty.util;
 
 import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
@@ -38,6 +39,7 @@
 import static org.hamcrest.Matchers.is;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertNull;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
@@ -89,13 +91,36 @@ public void testOverflow(Trie<Integer> trie) throws Exception
             if (!trie.put("prefix" + i, i))
             {
                 assertTrue(trie.isFull());
+                String key = "prefix" + i;
+
+                // Assert that all keys can be gotten.
+                for (String k : trie.keySet())
+                {
+                    assertNotNull(trie.get(k));
+                    assertNotNull(trie.get(toAsciiDirectByteBuffer(k, 0))); // has to be a direct buffer
+                    assertEquals(9, trie.get(toAsciiDirectByteBuffer(k, k.length()))); // has to be a direct buffer
+                }
+
+                // Assert that all getBest() variants do work on full tries.
+                assertNotNull(trie.getBest(key), "key=" + key);
+                assertNotNull(trie.getBest(key.getBytes(StandardCharsets.US_ASCII), 0, key.length()), "key=" + key);
+                assertNotNull(trie.getBest(toAsciiDirectByteBuffer(key, 0), 0, key.length()), "key=" + key); // has to be a direct buffer
+                assertNull(trie.getBest(toAsciiDirectByteBuffer(key, key.length()), 0, key.length()), "key=" + key);  // has to be a direct buffer
                 break;
             }
         }
 
         assertTrue(!trie.isFull() || !trie.put("overflow", 0));
     }
 
+    private static ByteBuffer toAsciiDirectByteBuffer(String s, int pos)
+    {
+        ByteBuffer bb = ByteBuffer.allocateDirect(s.length());
+        bb.put(s.getBytes(StandardCharsets.US_ASCII));
+        bb.position(pos);
+        return bb;
+    }
+
     @ParameterizedTest
     @MethodSource("implementations")
     public void testKeySet(Trie<Integer> trie) throws Exception