[Ocfs2-tools-devel] [PATCH 1/1] wireshark-ocfs2: add dlm_query_join response handler

[Sunil Mushran]

jeff.liu wrote:
>>> +static void dissect_dlm_query_join_response(proto_tree *tree,
>>> + proto_item *item,
>>> + tvbuff_t *tvb,
>>> + int offset)
>>> +{
>>> + union dlm_query_join_response response;
>>> + struct dlm_query_join_packet packet;
>>> + guint32 status;
>>> +
>>> + status = tvb_get_ntohl(tvb, offset);
>>> +
>>> + /* NOP if ocfs2-1.2.x message coming */
>>> + if (status < JOIN_PROTOCOL_MISMATCH)
>>> + return ;
>>
>> Not sure I understand this. Can't you key off the size of the packet?
> here my idea is, by comparing the status value with 
> JOIN_PROTOCOL_MISMATCH to determine the message version, since the 
> status value defined in old ocfs-1.2.9 should be dissected from 0 to 
> 3, but for 1.4.2 or newer, the status value is bigger than 3 due to 
> the structure changed and it was packed in big-endian.
>
> It's also easy to compute the packet size to determine the message 
> version by figure out the buffer size start from the offset of 
> "Magic". I'll submit the next version in this way if you think the 
> current approach is not reasonable.

We cannot rely on a specific value unless that value is hard coded
in the packet. Like a signature or message type, etc. In this specific
case, the assumption is that 1.4/mainline will not return JOIN_OK.
That's incorrect. Go with the packet size logic.