Re: supporting extend 'open live capture' parametes [was: setting the initial ring size]

["Abeni Paolo" <paolo.abeni () telecomitalia it>]

hello,

I assume that the my initial suggestion is going to be dismissed, right ?!?

on Thu 1/10/2008 10:47 AM  Guy Harris wrote:
> There'd also be an API to ask which parameters a particular adapter 
> supports (and possibly which values it supports for those parameters, 
> e.g. if one of the parameters is a DLT_ type or an 802.11 channel).

I think that a complete solution can be pretty complicated; such information could be provided with a buffer filled 
with TLV items, much like the 'extened open live capture' call. Supported values for each parameter could be inserted 
in the corresponding 'value' part of each item, putting all the supported values in the same item. A possible API could 
be:

int pcap_get_capabilities(const char* device_name, char* optbuf, unsigned size); /* fill optbuf up to size bytes with 
TLVs and returns error code or the number of bytes used */

There is an issue: optbuf can be not large enough to handle all supported parameters/values; we can enforce a 
reasonable upper bound for the TLVs buffer or we can use a TLV entry to specify the required buffer len.

To completed the picture, in extended open live capture the timeout parameter could be provided via the TLV buffer, 
since is not supported by all platform:

int pcap_open_live_ex(const char *device, int snaplen, int promisc, const char * optbuf, char *errbuf); 

What do you think? 

cheers,

Paolo
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