Hi All,
I've created a new dissector for USB PTP
(http://en.wikipedia.org/wiki/Picture_Transfer_Protocol) . This is the
protocol most digital cameras speak over USB. I've gotten far enough
to do the basic dissection, and I'm pretty stoked on the results!
The problem I have now is I have different possible values for a
value_string list, but they are data-dependent.
Contrived Example :
0x1 = 'Capture' if Nikon
0x1 = 'Erase' if Canon
To get around this I created a new typedef that I call
value_string_masked. There is a third entry in each row that gives a
mask specifying the type of camera that value is valid for. Shown in
this snippit:
typedef struct _value_string_masked {
guint32 mask;
guint32 value;
const gchar *strptr;
} value_string_masked;
static const value_string_masked usb_ptp_dpc_vals[] = {
{USB_PTP_FLAVOR_NIKON , 0xd010, "ShootingBank"},
{USB_PTP_FLAVOR_CANON , 0xd010, "MeteringMode"}
};
My question regarding creating and using a value_string list on the
fly. Somewhere in the packet stream I'll figure out if it's a Nikon or
a Canon.
1. I need to store that information in an attribute on the USB host.
I'm not sure where to store local values with relation to the data
coming from packet-usb.c
2. I need to create a value_string[] that has only the values that
match my mask, and use that for dissecting.
Can someone recommend an existing dissector I can use as sample code for
this?
I apologize if this is covered in the dev docs already, I'm still
"drinking from the firehose".
Thanks,
-m
