JAVA-2362: Throw exception if a one-byte BSON string is not properly null-terminated

Author: jyemin

bson/src/main/org/bson/io/ByteBufferBsonInput.java

@@ -142,7 +142,10 @@ public String readCString() {
     private String readString(final int size) {
         if (size == 2) {
             byte asciiByte = readByte();               // if only one byte in the string, it must be ascii.
-            readByte();                                // read null terminator
+            byte nullByte = readByte();                // read null terminator
+            if (nullByte != 0) {
+                throw new BsonSerializationException("Found a BSON string that is not null-terminated");
+            }
             if (asciiByte < 0) {
                 return UTF8_CHARSET.newDecoder().replacement();
             }

bson/src/test/unit/org/bson/io/ByteBufferBsonInputSpecification.groovy

@@ -396,4 +396,15 @@ class ByteBufferBsonInputSpecification extends Specification {
         then:
         thrown(BsonSerializationException)
     }
+
+    def 'should throw BsonSerializationException if a one-byte BSON string is not null-terminated'() {
+        given:
+        def stream = new ByteBufferBsonInput(new ByteBufNIO(ByteBuffer.wrap([2, 0, 0, 0, 1, 3] as byte[])))
+
+        when:
+        stream.readString()
+
+        then:
+        thrown(BsonSerializationException)
+    }
 }