Cleanup of Resolve fix for removed PackStruct (miekg#7)

* Cleanup of Resolve fix for removed PackStruct

The main header data is the same in every iteration, so it does not have
to be in the loop itself

* rename buffer vars to CamelCase

unbound.go

@@ -244,33 +244,34 @@ func (u *Unbound) Resolve(name string, rrtype, rrclass uint16) (*Result, error)
 		r.Data = make([][]byte, 0)
 		r.Rr = make([]dns.RR, 0)
 		b := C.GoBytes(unsafe.Pointer(C.array_elem_char(res.data, C.int(j))), C.array_elem_int(res.len, C.int(j)))
+
+        // Create the RR; write out the header details and
+        // the rdata to a buffer, and unpack it again into an
+        // actual RR, for ever rr found by resolve
+        hdrBuf := make([]byte, len(h.Name) + 11)
+        off, _ := dns.PackDomainName(h.Name, hdrBuf, 0, nil, false)
+        binary.BigEndian.PutUint16(hdrBuf[off:], h.Rrtype)
+        off += 2
+        binary.BigEndian.PutUint16(hdrBuf[off:], h.Class)
+        off += 2
+        binary.BigEndian.PutUint32(hdrBuf[off:], h.Ttl)
+        off += 4
+
 		for len(b) != 0 {
-			// Create the RR; write out the header details and
-            // the rdata to a buffer, and unpack it again into an
-            // actual RR
 			h.Rdlength = uint16(len(b))
+            // Note: we are rewriting the rdata len so we do not
+            // increase off anymore.
+            binary.BigEndian.PutUint16(hdrBuf[off:], h.Rdlength)
+            rrBuf := append(hdrBuf, b...)
 
-			msg := make([]byte, len(h.Name) + 11)
-			off, _ := dns.PackDomainName(h.Name, msg, 0, nil, false)
-			binary.BigEndian.PutUint16(msg[off:], h.Rrtype)
-			off += 2
-			binary.BigEndian.PutUint16(msg[off:], h.Class)
-			off += 2
-			binary.BigEndian.PutUint32(msg[off:], h.Ttl)
-			off += 4
-			binary.BigEndian.PutUint16(msg[off:], h.Rdlength)
-			off += 2
-			rrbuf := append(msg, b...)
-
-			rr, _, err := dns.UnpackRR(rrbuf, 0)
+			rr, _, err := dns.UnpackRR(rrBuf, 0)
 			if err == nil {
 				r.Rr = append(r.Rr, rr)
 			}
 
 			r.Data = append(r.Data, b)
 			j++
 			b = C.GoBytes(unsafe.Pointer(C.array_elem_char(res.data, C.int(j))), C.array_elem_int(res.len, C.int(j)))
-
 		}
 	}
 	return r, err