Fixed a bug when looking up IPv4 addresses in IPv6 tree.

This only happened when there was no IPv4 subtree and the first
bit of the address was 1.

Author: oschwald

src/main/java/com/maxmind/maxminddb/MaxMindDbReader.java

@@ -98,17 +98,19 @@ private int findAddressInTree(InetAddress address)
         int record = this.startNode(bitLength);
 
         for (int i = 0; i < bitLength; i++) {
+            if (record >= this.metadata.nodeCount) {
+                break;
+            }
             int b = 0xFF & rawAddress[i / 8];
             int bit = 1 & (b >> 7 - (i % 8));
             record = this.readNode(record, bit);
-
-            if (record == this.metadata.nodeCount) {
-                // record is empty
-                return 0;
-            } else if (record > this.metadata.nodeCount) {
-                // record is a data pointer
-                return record;
-            }
+        }
+        if (record == this.metadata.nodeCount) {
+            // record is empty
+            return 0;
+        } else if (record > this.metadata.nodeCount) {
+            // record is a data pointer
+            return record;
         }
         throw new InvalidDatabaseException("Something bad happened");
     }
@@ -135,12 +137,8 @@ private int ipV4StartNode() throws InvalidDatabaseException {
             return this.ipV4Start;
         }
         int node = 0;
-        for (int i = 0; i < 96; i++) {
-            int nextNode = this.readNode(node, 0);
-            if (nextNode >= this.metadata.nodeCount) {
-                break;
-            }
-            node = nextNode;
+        for (int i = 0; i < 96 && node < this.metadata.nodeCount; i++) {
+            node = this.readNode(node, 0);
         }
         this.ipV4Start = node;
         return node;

src/test/java/com/maxmind/maxminddb/ReaderTest.java

@@ -53,6 +53,8 @@ public void testNoIpV4SearchTree() throws IOException, URISyntaxException {
 
         assertEquals("::/64", reader.get(InetAddress.getByName("1.1.1.1"))
                 .textValue());
+        assertEquals("::/64", reader.get(InetAddress.getByName("192.1.1.1"))
+                .textValue());
     }
 
     private void testMetadata(MaxMindDbReader reader, int ipVersion,