Windows interfaces GUIDs issue caused reverse DNS resolution to fail

[Robert Croteau <robert.croteau () quest com>]

Hi all,

I installed the windows version of 7.31 on Windows Server 2016 and I couldn't get the reverse DNS hostname in the 
results.
The following message:

    "mass_dns: warning: Unable to determine any DNS servers. Reverse DNS is disabled. Try using --system-dns or specify 
valid servers with --dns-servers"

appeared in the output.  I could also get the following message if I installed winpcap first then installed nmap (with 
npcap):

    "Interface XXXXXXX is not known; ignoring its nameservers."

It seems the following code is the culprit:

nmap_dns.cc :940
if (strcmp(guid, pcap_guid) == 0)
    return true;

should be changed to

if (strcasecmp(guid, pcap_guid) == 0)
    return true;

The issue seems to be that an interface GUID in 
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\Tcpip\Parameters\Interfaces can either be defined in uppercase or 
lowercase but internally to nmap (from npcap?) the interface list is saved as uppercase.  So in my case, my interfaces 
were lowercase and did not match the interfaces from the  list returned by getinterfaces() in 
interface_is_known_by_guid().

Using strcasecmp() instead of strcmp() solved the problem.
Hope this helps.

Thanks

Robert-André Croteau

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