[ovs-discuss] OpenVSwitch - Error packet OFPFMFC_BAD_COMMAND of code ofp_flow_mod_failed_code coming as malformed.

[Ben Pfaff]

On Mon, May 21, 2012 at 11:15:28AM +0000, Prabina Pattnaik wrote:
> As per openflow 1.0 spec "data" contains at "least" first 64 bytes
> of failed request. This is working correct also in current OVS 1.2.2
> code.
>
> But it is taking an extra check in code (lib/ofp-util.c) on "data"
> length that:-
>
> if data is greater than 64 bytes then it would be truncated to 64
> bytes which is making this packet as malformed. OVS code is working
> on "at most" 64 bytes length instead of "at least" 64 bytes.
> 
> To avoid the truncation of 'data field ' to 64 bytes, the condition
> to check the length of data field in file (lib/ofp-util.c), routine
> ofputil_encode_error_msg can be removed.

I disagree with your interpretation.  "At least" 64 bytes means that
OVS is allowed to truncate the inner message after 64 bytes.  That is
what it is doing.