Re: libpcap: patches required for OpenSolaris/SXCE

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

On Dec 1, 2009, at 6:37 AM, Sebastien Roy wrote:

> I would argue that it's a bug on Solaris that libpcap depends on
> IP-layer information to choose a capture interface (if that is in fact
> what it does),

It depends on whatever mechanisms the OS provides that supply a list  
of interfaces.  If the OS provides no mechanism that can supply  
interfaces with no IP addresses, that's not a libpcap bug *on* the OS  
in question, it's a deficiency *in* the OS in question.

> bash-3.2# tcpdump -i bge0
> tcpdump: WARNING: SIOCGIFADDR: bge0: No such device or address

This means "sorry, if you're expecting -f to work or a filter  
containing 'ip broadcast' to work, you're going to be disappointed".

Does the errno corresponding to "No such device or address", when  
returned by ioctl(SIOCGIFADDR), mean "this device doesn't have an  
address of the type"?  Or can it also mean "there is no such device"?

> The WARNING there seems spurious, and the use of SIOCGIFADDR
> questionable.  Why should tcpdump care about the IP addresses assigned
> to bge0 when observing at the link-layer?

See above.  If pcap_lookupnet () fails, we can immediately report the  
failure as an error if -f is specified, and possibly specify the out- 
of-range netmask value to pcap_compile() if -f is not specified, and  
have pcap_compile() report an error in that case.

> FWIW, it appears to select a
> default interface just fine, so it would appear to not use the SIOCG*
> socket ioctls for interface selection:

Nope, it uses SIOCGLIFCONF.
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