[trac697] add test for dns parse error in response

src/lib/resolve/tests/recursive_query_unittest_2.cc

@@ -101,11 +101,13 @@ public:
     /// Set before the query and then by each "server" when responding.
     enum QueryStatus {
         NONE = 0,                   ///< Default
-        UDP_ROOT = 1,               ///< Query root server over UDP
-        UDP_ORG = 2,                ///< Query ORG server over UDP
-        TCP_ORG = 3,                ///< Query ORG server over TCP
-        UDP_EXAMPLE_ORG = 4,        ///< Query EXAMPLE.ORG server over UDP
-        COMPLETE = 5                ///< Query is complete
+        UDP_ROOT,                   ///< Query root server over UDP
+        UDP_ORG,                    ///< Query ORG server over UDP
+        TCP_ORG,                    ///< Query ORG server over TCP
+        UDP_EXAMPLE_ORG_BAD,        ///< Query EXAMPLE.ORG server over UDP
+                                    ///< (return malformed packet)
+        UDP_EXAMPLE_ORG,            ///< Query EXAMPLE.ORG server over UDP
+        COMPLETE                    ///< Query is complete
     };
 
     // Common stuff
@@ -305,6 +307,12 @@ public:
             expected_ = TCP_ORG;
             break;
 
+         case UDP_EXAMPLE_ORG_BAD:
+            // Return the answer to the question.
+            setAnswerWwwExampleOrg(msg);
+            // Set new expected in check below
+            break;
+
          case UDP_EXAMPLE_ORG:
             // Return the answer to the question.
             setAnswerWwwExampleOrg(msg);
@@ -320,6 +328,13 @@ public:
         MessageRenderer renderer(*udp_send_buffer_);
         msg.toWire(renderer);
 
+        if (expected_ == UDP_EXAMPLE_ORG_BAD) {
+            // mangle the packet a bit
+            // set additional to one more
+            udp_send_buffer_->writeUint8At(3, 11);
+            expected_ = UDP_EXAMPLE_ORG;
+        }
+
         // Return a message back to the IOFetch object (after setting the
         // expected length of data for the check in the send handler).
         udp_length_ = udp_send_buffer_->getLength();
@@ -450,7 +465,7 @@ public:
         // readiness for the next read. (If any - at present, there is only
         // one read in the test, although extensions to this test suite could
         // change that.)
-        expected_ = UDP_EXAMPLE_ORG;
+        expected_ = UDP_EXAMPLE_ORG_BAD;
         tcp_cumulative_ = 0;
 
         // Unless we go through a callback loop we cannot simply use