Re: [Wireshark-commits] rev 30846: /trunk/gtk/ /trunk/gtk/: capture_if_dlg.c

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

On Nov 7, 2009, at 10:38 AM, Gerald Combs wrote:

> In capture_interface_list we don't set the interface description if we
> get an empty string from dumpcap:
>
>         if (strlen(if_parts[1]) > 0)
>             if_info->description = g_strdup(if_parts[1]);

Hmm.

Looking at capture_opts_list_interfaces(), which is what dumpcap uses  
to list the interfaces, if it's generating (more easily) machine- 
readable output, the output generated for a missing description  
(if_info->description is null) and the output generated for an empty  
description (if_info->description points to a null string) are the same.

> This is apparently how we ended up with null description pointers in
> capture_get_if_icon. Should we take out the if statement and set the
> description no matter what?

An empty description is no more useful than a null description, and,  
as indicated, pcap_findalldevs() doesn't guarantee that it will return  
a description for every adapter, so I wouldn't be inclined to do that;  
I'd be inclined to leave the if statement there.

(I'm thinking of redoing the way that dumpcap communicates with its  
callers for various reasons, including adding support for all the new  
stuff I added in libpcap 1.0, so, for example, we can have a "monitor  
mode" checkbox for wireless adapters if the relevant APIs work; I'll  
see if I can distinguish between "no description" and "empty  
description".)

I'm also curious how the description managed to be null - at least  
according to the bug report, Marvell *does* supply a description:

    Connection-specific DNS Suffix  . :
    Description . . . . . . . . . . . : Marvell Yukon 88E8056 PCI-E  
Gigabit Ethernet Controller
    Physical Address. . . . . . . . . : 00-22-15-##-##-##
    DHCP Enabled. . . . . . . . . . . : Yes
    Autoconfiguration Enabled . . . . : Yes
    Link-local IPv6 Address . . . . . : fe80::####::####.....
    IPv4 Address. . . . . . . . . . . : a.b.c.h(Preferred)
    Subnet Mask . . . . . . . . . . . : w.x.y.z
    Lease Obtained. . . . . . . . . . : 06 November 2009 18:38:00
    Lease Expires . . . . . . . . . . : 09 November 2009 18:37:59
    Default Gateway . . . . . . . . . : a.b.c.d
    DHCP Server . . . . . . . . . . . : a.b.c.d
    DNS Servers . . . . . . . . . . . : a.b.c.d
    NetBIOS over Tcpip. . . . . . . . : Enabled

so there's presumably something odd going on in WinPcap here.
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