Re: libdlpi with libpcap

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

sagun shakya wrote:

> When the features mentioned above integrate into Solaris, an extensible 
> way to open DLPI links under different directories will be required. The 
> libdlpi(3LIB) library provides an interface that provides an abstraction 
> around this so that DLPI applications do not need to know where the 
> actual DLPI link is located in the filesystem.

Is there an error returned by dlpi_open() that means "there is no such 
network device?  If so, which error is it?

Also, is there an error that means "there is such a device, but you 
don't have permission to open it"?

I'd like to have libpcap be able to return special error codes for those 
two errors in pcap_activate(), rather than reporting a generic error 
indication with a text string, so the application can more easily 
determine the specific error and perhaps treat those errors specially - 
those errors are usually the result of the user mistyping a device name 
or running the program without sufficient privileges, so the application 
might want to indicate that more clearly.

Speaking of sufficient privileges, at least when I last tried it, you 
could give users other than root privileges to open DLPI devices, but 
you couldn't enable promiscuous mode unless you're root - and, in 
non-promiscuous mode, you couldn't see outgoing traffic (I suppose one 
could argue that outgoing traffic isn't being sent to your machine, so 
you shouldn't see it in non-promiscuous mode - but, if you're trying to 
capture your machine's traffic, you don't have an option to do that; 
NDIS in Windows has a NDIS_PACKET_TYPE_ALL_LOCAL "filter" which lets you 
see both incoming and outgoing packets, as well as 
NDIS_PACKET_TYPE_DIRECTED to see incoming unicast packets, 
NDIS_PACKET_TYPE_MULTICAST to see incoming multicast packets the adapter 
is set up to see, NDIS_PACKET_TYPE_ALL_MULTICAST to see all incoming 
multicast packets, NDIS_PACKET_TYPE_BROADCAST to see all incoming 
broadcast packets, and NDIS_PACKET_TYPE_PROMISCUOUS to see all incoming 
packets including those not intended for the host).
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