Re: pcap DLT request for virtio-scsi SCSI transport

[Guy Harris <guy () alum mit edu>]

On Mar 3, 2012, at 3:38 AM, Stefan Hajnoczi wrote:

> There are SCSI commands and responses.  Commands and responses are
> separate pcap packets because there can be multiple outstanding
> commands to multiple targets/LUNs.
>
> From the spec, commands have the following layout:
>
>    u8 lun[8];
>    u64 id;
>    u8 task_attr;
>    u8 prio;
>    u8 crn;
>    char cdb[cdb_size];

(Presumably the CDB size depends on the command.)

>    char dataout[];
>
> Responses have the following layout:
>
>    u32 sense_len;
>    u32 residual;
>    u16 status_qualifier;
>    u8 status;
>    u8 response;
>    u8 sense[sense_size];
>    char datain[];
>
> The pcap mapping of this layout should be straightforward.

So does a command packet begin with 8 bytes of LUN, and a response packet begin with 4 bytes of sense length?

If so, how do you distinguish between a command packet and a response packet?

Or is there additional metadata at the beginning of the packet to indicate whether a packet is a command or a response?-
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