[2013] revised log message description on broken wire-format data.

src/bin/ddns/ddns_messages.mes

@@ -72,14 +72,14 @@ and will now shut down.
 
 % DDNS_REQUEST_PARSE_FAIL failed to parse update request: %1
 b10-ddns received an update request via b10-auth, but the received
-data failed to pass minimum validation: it was either totally broken
-as an any valid DNS message (there can be many reasons for that), or
-the opcode is not update, or TSIG is included in the request but it
-fails to validate.  Since b10-auth should have performed this level of
-checks, such an error shouldn't be detected at this stage and should
-rather be considered an internal bug.  This event is therefore logged
-at the error level, and the request is simply dropped.  Additional
-information of the error is also logged.
+data failed to pass minimum validation: it was either broken wire
+format data for a valid DNS message (e.g. it's shorter than the
+fixed-length header), or the opcode is not update, or TSIG is included
+in the request but it fails to validate.  Since b10-auth should have
+performed this level of checks, such an error shouldn't be detected at
+this stage and should rather be considered an internal bug.  This
+event is therefore logged at the error level, and the request is
+simply dropped.  Additional information of the error is also logged.
 
 % DDNS_RESPONSE_SOCKET_ERROR failed to send update response to %1: %2
 Network I/O error happens in sending an update request.  The